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Faculty Publication (2017)

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1. Albritton, H.L.Kozlowski, P.A.Lillis, R.A., McGowin, C.L.,Siren, J.D.Taylor, S.N., Ibana, J.A.,Buckner, L.R.Shen, L.Quayle, A.J. (2017). A novel whole-bacterial enzyme linked-immunosorbant assay to quantify Chlamydia trachomatis specific antibodies reveals distinct differences between systemic and genital compartment. PLoS One.


Chlamydia trachomatis (CT) is the leading sexually transmitted bacterial infection. The continued global burden of CT infection strongly predicates the need for a vaccine to supplement current chlamydial control programs. The correlates of protection against CT are currently unknown, but they must be carefully defined to guide vaccine design. The localized nature of chlamydial infection in columnar epithelial cells of the genital tract necessitates investigation of immunity at the site of infection. The purpose of this study was to develop a sensitive whole bacterial enzyme-linked immunosorbent assay (ELISA) to quantify and compare CT-specific IgG and IgA in sera and genital secretions from CT-infected women. To achieve this, elementary bodies (EBs) from two of the most common genital serovars (D and E) were attached to poly-L-lysine-coated microtiter plates with glutaraldehyde. EB attachment and integrity were verified by the presence of outer membrane antigens and the absence of bacterial cytoplasmic antigens. EB-specific IgG and IgA standards were developed by pooling sera with high titers of CT-specific antibodies from infected women. Serum, endocervical and vaginal secretions, and endocervical cytobrush specimens from CT-infected women were used to quantify CT-specific IgG and IgA which were then normalized to total IgG and IgA, respectively. Analyses of paired serum and genital samples revealed significantly higher proportions of EB-specific antibodies in genital secretions compared to sera. Cervical and vaginal secretions and cytobrush specimens had similar proportions of EB-specific antibodies, suggesting any one of these genital sampling techniques could be used to quantify CT-specific antibodies when appropriate normalization methodologies are implemented. Overall, these results illustrate the need to investigate genital tract CT antibody responses, and our assay provides a useful quantitative tool to assess natural immunity in defined clinical groups and CT vaccine trials. 

2. Anticamara, J. A., & Go, K. T. B. (2017). Impacts of super-typhoon Yolanda on Philippine reefs and communities. Regional Environmental Change, 17(3), 1–11.more


This report presents super-typhoon Yolanda’s impacts on coral reefs of Eastern Samar, Philippines, and evaluates its implications on resource management in the area. Coral reefs suffer regular impacts of typhoons, and typhoons nowadays are stronger in magnitude, longer in duration, more frequent in occurrence, and larger in scale. Thus, there is a great need to understand the impacts and consequences of super-typhoons on reefs and the coastal communities. Yolanda is the strongest recorded typhoon to make a landfall. Here is the first account of Yolanda’s impacts on corals and benthic organisms, reef fish, and fisheries production. Our study sites covered Lawaan, Balangiga, Giporlos, Quinapondan, Salcedo, and Guiuan in Eastern Samar, Philippines—municipalities that were greatly damaged by Yolanda. To quantify the impacts of Yolanda on coral reefs, we compared coral cover and diversity, and fish abundance, biomass, and diversity between sites before and after Yolanda. We found that some reef areas were completely wiped out by Yolanda (i.e., the shallow branching reefs), but other reef sites were only partially damaged. The extent of damages depends on reef locations relative to Yolanda’s trajectory, depth, coral species composition, and reef condition prior to Yolanda. We also found that most reefs in the area already suffered degradation prior to Yolanda (i.e., due to overfishing, destructive fishing, and siltation from land). Active coral restoration, reduction in fishing effort, diversification of economic activities, and effective management of no-take marine reserves should play key roles in the recovery of resources and human lives in these devastated areas.

3. Buhian, W. P. C., Rubio, R. O., & Martin-Puzon, J. J. (2017). Chromatographic fingerprinting and free-radical scavenging activity of ethanol extracts of Muntingia calabura L. leaves and stems. Asian Pacific Journal of Tropical Biomedicine, 7(2), Pages 139–143. more



To determine the thin-layer chromatography (TLC) fingerprint profiles and to evaluate the in vitro antioxidant activity of ethanol extracts of Muntingia calabura (M. calabura) leaves and stems.


The leaves and stems were extracted using ethanol as solvent. The TLC separation of the phytochemical constituents of the leaf and ethanol extracts was carried out in ethyl acetate: n-hexane and chloroform: ethyl acetate mobile phase systems. Distinct spots were visualized under visible light, UV 254 nm, UV 366 nm and after spraying with vanillin-sulfuric acid. The 2,2-diphenyl-1-picrylhydrazyl free-radical scavenging assay was used to evaluate the antioxidant activity of the extracts.


Both the leaf and stem ethanol extracts at 4 mg/mL exhibited 2,2-diphenyl-1-picrylhydrazyl inhibition of more than 90%, relative to gallic acid. The results of TLC showed that the degree of resolution between the constituent spots was comparable between the two mobile phase systems using the different visualization wavelengths. Under the 254 nm visualization, few spots were observed in leaf and stem extracts. Visualization at 366 nm yielded the greatest number of observable spots of various colors in both leaf and stem extracts. More spots were visualized upon post-derivatization with vanillin-sulfuric acid in the TLC chromatograms using chloroform: ethyl acetate mobile phase, compared to those in ethyl acetate: n-hexane mobile phase.


M. calabura exhibited very high antioxidant activity in its leaves and stems ethanol extracts, both of which are used in traditional medicine. The TLC results demonstrated the presence of diverse secondary metabolites in the leaf and stem ethanol extracts, indicating that the antioxidant activity, including other bioactivities may be attributed to these phytochemical constituents. This paper has reported for the first time the TLC fingerprinting of M. calabura using visible light, UV 254 nm, UV 366 and post-derivatization with vanillin-spray to visualize separate spots on TLC plates. 

4. Calayag, A. M. B., Paclibare, P. A. P., Santos, P. D. M., Bautista, C. A. C., & Rivera, W. L. (2017). Molecular characterization and antimicrobial resistance of Salmonella enterica from swine slaughtered in two different types of Philippine abattoir. Food Microbiology, 65, 51–56. more


Salmonella entericais a well-known pathogen commonly acquired from the consumption of contaminated food. It has been estimated to affect millions of humans and cause hundreds of thousands of deaths per year globally. Pork, one of the most commonly consumed meats worldwide, has been identified as one of the main sources of human salmonellosis. In this study, we aimed to detect and characterizeS. entericafrom slaughtered swine and generate antimicrobial resistance profiles of select isolates. Tonsils and jejunum with mesenteric lymph nodes (MLN) were collected from a total of 240 swine from eight abattoirs (five accredited and three locally registered abattoirs) across Metro Manila.S. entericawere isolated using conventional culture methods and confirmed by PCR amplification of theinvAgene. Isolates were further characterized based on somatic antigen by multiplex PCR. We report that there is no significant difference (P = 0.42) between the incidences ofS. entericain swine slaughtered in accredited (44.0%) and in locally registered abattoirs (46.7%). Most samples were contaminated withS. entericaunder serogroup O:3,10. Antimicrobial susceptibility testing of 183 isolates using the VITEK®2 system revealed high resistance to ampicillin (67.8%) and trimethoprim/sulfamethoxazole (80.3%). Multidrug-resistance was found in 124 (67.8%) isolates.

5. Cruaud, P., Rasplus, J.-Y., Rodriguez, L. J., & Cruaud, A. (2017). High throughput sequencing of multiple amplicons for barcoding and integrative taxonomy. Scientific Reports, 7more


Until now, the potential of NGS for the construction of barcode libraries or integrative taxonomy has been seldom realised. Here, we amplified (two-step PCR) and simultaneously sequenced (MiSeq) multiple markers from hundreds of fig wasp specimens. We also developed a workflow for quality control of the data. Illumina and Sanger sequences accumulated in the past years were compared. Interestingly, primers and PCR conditions used for the Sanger approach did not require optimisation to construct the MiSeq library. After quality controls, 87% of the species (76% of the specimens) had a valid MiSeq sequence for each marker. Importantly, major clusters did not always correspond to the targeted loci. Nine specimens exhibited two divergent sequences (up to 10%). In 95% of the species, MiSeq and Sanger sequences obtained from the same sampling were similar. For the remaining 5%, species were paraphyletic or the sequences clustered into divergent groups on the Sanger+MiSeq trees (>7%). These problematic cases may represent coding NUMTS or heteroplasms. Our results illustrate that Illumina approaches are not artefact-free and confirm that Sanger databases can contain non-target genes. This highlights the importance of quality controls, working with taxonomists and using multiple markers for DNA-taxonomy or species diversity assessment.

6. Dumilag, R. V., & Aguinaldo, Z.-Z. A. (2017). Genetic differentiation and distribution of Pyropia acanthophora (Bangiales, Rhodophyta) in the Philippines. European Journal of Phycology, 0(0), Pages 1–12. more


Pyropia acanthophorais a foliose Bangiales with widely known endemic populations in Indo-Pacific region. This alga has expanded its range recently as a consequence of introduction. In an attempt to explore the genetic diversity of Py. acanthophora within the Philippines and the impact of the introduction of the species from elsewhere, an examination of molecular differentiation and distribution was undertaken using the mitochondrial COI-5P and plastid rbcL gene sequences. The results revealed that the populations of Py. acanthophora in the Philippines exhibited high haplotypic and genetic diversities, and were found to be distinct from those previously reported as conspecific populations found in Taiwan, India, Japan, Hawaii, and from those introduced populations from Brazil. The network analyses as inferred fromrbcL and from the combined COI-5P and rbcL genes showed evidence that the Philippine populations of Py. acanthophora exhibited a chaotic patchiness pattern characterized by a population with highly site-exclusive haplotypes, wide genet ic variability and lack of local geographic patterns. The distribution of Py. acanthophora within the Philippines was also found to be greater than what was previously known, ranging from the extreme northwest to extreme northeast mainland Luzon coasts, including Camiguin Is., Cagayan. Understanding the genetic diversity and distribution of Py. acanthophora in the Philippines provides valuable information in relation to the conservation and effective resource management of native populations of Py. acanthophora in the tropical Asian region.


7. Dumilag, R.V., Aguinaldo, Z.-Z.A., Mintu, C.B., Quinto, M.P., Ame, E.C., Andres, R.C., Monotilla, W.D., Yap, S.L., Cao, E.P., Vital, P.G., Fontanilla, I.K.C. (2017). A review of the current taxonomic status of foliose bangiales (Rhodophyta) in the Philippines. Phytoxaxa, 312(1), 47-59.more


Causes of taxonomic confusion are lamentably well known in foliose Bangiales. A magnitude of these uncertainties stems from the paucity of available taxonomic traits in morphologically homoplastic species. At present, the taxonomic identity and systematics of many of the Philippine foliose Bangiales are in a state of flux. A critical examination of published literature on Philippine records of 10 species of foliose Bangiales has rendered the need for re-confirmation of the presence of Porphyra atropurpurea, Porphyra marcosii, Pyropia denticulata, and Pyropia suborbiculata while records of Porphyra umbilicalis, Pyropia vietnamensis, Wildemania variegata, and the invalid name Porphyra crispata have been omitted from the list. Currently, there are only two confirmed species of foliose Bangiales in the Philippines, which are Pyropia acanthophora and Pyropia tanegashimensis. Thus, this review exhorts a re-examination of collected Philippine foliose Bangiales materials using both morphological and molecular analysis.

8. Fontanilla, I.K., Naggs, F., Wade, C.M. (2017). Molecular phylogeny of the Achatinoidea (Mollusca:Gastropoda). Molecular Phylogenetics and Evolution, 114, Pages 382-385.more


This study presents a multi-gene phylogenetic analysis of the Achatinoidea and provides an initial basis for a taxonomic re-evaluation of family level groups within the superfamily. A total of 5028 nucleotides from the nuclear rRNA, actin and histone 3 genes and the 1st and 2nd codon positions of the mitochondrial cytochrome c oxidase subunit I gene were sequenced from 24 species, representing six currently recognised families. Results from maximum likelihood, neighbour joining, maximum parsimony and Bayesian inference trees revealed that, of currently recognised families, only the Achatinidae are monophyletic. For the Ferussaciidae, Ferussacia folliculus fell separately to Cecilioides gokweanus and formed a sister taxon to the rest of the Achatinoidea. For the Coeliaxidae, Coeliaxis blandii and Pyrgina umbilicata did not group together. The Subulinidae was not resolved, with some subulinids clustering with the Coeliaxidae and Thyrophorellidae. Three subfamilies currently included within the Subulinidae based on current taxonomy likewise did not form monophyletic groups.

9. Hallare, A. V, Luis, J., Chan, A. C., Maria, B., Tan, S. P., Rubio, P. Y. M., … Macabeo, A. P. G. (2017). Toxicological Analysis of Phthalates from Dust Samples Collected in Selected Philippine Light Rail Transit Stations. Nature Environment and Pollution Technology, 16(1), Pages 11–19. 


Phthalates are the most common form of plasticizers. Due to the ease with which phthalates diffuse from their plastics and the sheer volume of plastics that have been introduced to the environment, they represent one of the most ubiquitous and persistent chemicals known. Phthalates are known to have several toxic effects. The study was carried out to identify the phthalates found in the urban dusts that have accumulated from underneath the LRT1 stations at Monumento, R. Papa, and EDSA in Metro Manila, and to determine their embryotoxic potential. The urban dust samples were subjected to solid phase extraction (SPE) and gas chromatography-mass spectrometry (GC-MS). Six phthalates were identified, and the extract was then used in the zebrafish embryo toxicity (ZFET) test. Lethal and sublethal end points were observed in the zebrafish embryos. Low dilutions were found to be highly embryo toxic and a dose-response relationship was seen in dilutions ranging from 1:4 to 1:40. The LC50of the phthalate mixture was also obtained and found to be 9.188 μg/mL. This study elucidated some of the toxic effects of the phthalates, but further studies must be performed to evaluate the toxicity of the individual phthalates, some of whose effects are relatively unknown.


10. Lee, J., Rodriguez, J.P., Quilantang, N.G., Lee, M.-H., Cho, E.J., Jacinto, S.D., Lee, S. (2017). Determination of flavonoids from Perilla frutescens var. japonica seeds and their inhibitory effect on aldose reductaseApplied Biological Chemistry, 60(2), pages 155-162. more


Perilla frutescens var. japonica (PF) is an annual aromatic herb has been consumed as a food ingredient and medicinal crop in Asian countries. To evaluate the therapeutic efficacy of aldose reductase (AR) inhibition, we tested the PF seeds. The stepwise polarities of PF were tested for AR inhibition, and we determined the CH2Cl2and EtOAc fractions to be good inhibitors (5.81 and 3.99 μg/mL, respectively). Compounds 1–3 were isolated from the CH2Cl2and EtOAc fractions and identified as luteolin (1), apigenin (2), and diosmetin (3) by physicochemical and spectroscopic data. Among them, luteolin (1) and apigenin (2) had high AR inhibitory activity (1.89 and 4.18 μM). Deulsaem, a variety of PF, was determined to have the highest flavonoid content among ten PF seeds tested (2.10 mg/g). This study suggests that PF could be utilized as a natural source to treat diabetic complications. 


11. Marquez, C. M. D., Ibana, J. A., & Velarde, M. C. (2017). The female reproduction and senescence nexus. American Journal of Reproductive Immunology.more


Successful pregnancy is regulated by several soluble factors that are differentially expressed throughout gestation. These factors are important to initiate and establish embryo implantation and parturition. Senescent cells, which undergo permanent cell proliferation arrest in response to stress, also produce several secreted factors, referred to as the senescence-associated secretory phenotype (SASP). Here, we review some of the secreted factors found during early and late pregnancy and compare their expression profile with those of the SASP. Because senescent cells are found in the uterus and embryo during pregnancy, we hypothesize that SASP factors contribute to successful pregnancy. We discuss how senescent cells may support embryo development and signal parturition. We provide evidences for potential contribution of SASP to the physiology and pathophysiology of pregnancy.


12. Moritz, G.L., Ong, P.S., Perry, G.H., Dominy, N.J. (2017). Functional preservation and variation in the cone opsin genes of nocturnal tarsiers. Philosophical Transaction of the Royal Society B: Biological Science, 372 (1717).more


The short-wavelength sensitive (S-) opsin gene OPN1SW is pseudogenized in some nocturnal primates and retained in others, enabling dichromatic colour vision. Debate on the functional significance of this variation has focused on dark conditions, yet many nocturnal species initiate activity under dim (mesopic) light levels that can support colour vision. Tarsiers are nocturnal, twilight-active primates and exemplary visual predators; they also express different colour vision phenotypes, raising the possibility of discrete adaptations to mesopic conditions. To explore this premise, we conducted a field study in two stages. First, to estimate the level of functional constraint on colour vision, we sequenced OPN1SW in 12 wild-caught Philippine tarsiers (Tarsius syrichta). Second, to explore whether the dichromatic visual systems of Philippine and Bornean (Tarsius bancanus) tarsiers—which express alternate versions of the medium/long-wavelength sensitive (M/L-) opsin gene OPN1MW/OPN1LW—confer differential advantages specific to their respective habitats, we used twilight and moonlight conditions to model the visual contrasts of invertebrate prey. We detected a signature of purifying selection for OPN1SW, indicating that colour vision confers an adaptive advantage to tarsiers. However, this advantage extends to a relatively small proportion of prey–background contrasts, and mostly brown arthropod prey amid leaf litter. We also found that the colour vision of T. bancanus is advantageous for discriminating prey under twilight that is enriched in shorter (bluer) wavelengths, a plausible idiosyncrasy of understorey habitats in Borneo.

13. Oponda, C.V.L, Santos, B.S., Basiao, Z.U. (2017). Morphological differences in five strains of genetically improved nile tilapia (Oreochromis niloticus) using geometric morphometric. Journal of the International Society for South Asian Agricultural Sciences, 23(1), Pages 44-55.more


The determination of fish stock structure is important in developing optimal strategies for efficient management of aquaculture species. Morphometric analysis provides a robust, non-expensive, and statistically powerful means of stock delineation. In the Philippines, five strains of genetically improved Nile tilapia (Oreochromis niloticus) have been developed. This study sought to use geometric morphometrics to delineate among the five tilapia strains. Specimens were collected in June to December 2014 from various institutions in the Philippines. Images of 263 individuals were taken at four months old, and 17 landmarks were digitized. Multivariate analysis of variance (MANOVA) revealed significant shape differences between strains. The Canonical Variate Analysis (CVA) plot showed the SEAFDEC strain to be most unique in shape whereas close similarity was observed among specimens of GIFT Philippines, GIFT Malaysia and GET-EXCEL. Discriminant groupings by CVA reflect the historical relationships among the strains. Morphological traits such as the tip of the snout, insertion of the pelvic fin, ventral base of the caudal fin, and the anterior end of the dorsal fin can be used to differentiate one strain from another. Sexual dimorphism in shape was also evident. These results indicate the utility of geometric morphometrics in delineating strains of economically important fish species. 

14. Pagalilauan, H.A.M, Paraoan, C.E.M., Vital, P.G. (2017). Detection of pathogenic bioaerosols and occupational risk in a Philippine landfill site. Journal Archives of Environmental & Occupational Health. Pages 1-8. more


Payatas landfill site is one of the major dumpsites in the Philippines. In this study, the landfill was evaluated regarding the presence and concentration of pathogenic bacterial aerosols through culture and molecular techniques. Bioaerosols are biological airborne particles that may or may not cause diseases. Active sampling was done using MAS-100 Air Sampler from both indoor and outdoor locations. To test the accuracy of the culture method, those that were presumptively identified as Staphylococcus aureus and Klebsiella pneumoniae were subjected to molecular analysis using 16s rRNA sequencing, and as a result, they were identified as different species. The exposure assessment done by interview showed matches among prevalent diseases. The results of this study can be used as a basis for creating standards and regulations for workers' and residents' safety and health in the landfill site.


15. Paraoan, C.E.M., Rivera, W.L., Vital, P.G. (2017). Detection of Class I and II integrons for the assessment of antibiotic and multidrug resistance amongEscherichia coliisolates from agricultural irrigation waters in Bulacan, Philippines. Journal of Environmental Science and Health - Part B Pesticides, Food Contaminants, and Agricultural Wastes. 52 (5), Pages 306-313. more


Contaminated irrigation water may greatly affect not only the quality of produce but also the people exposed to it. In this study, agricultural irrigation waters in Bulacan, Philippines were assessed and found to be contaminated with Escherichia coli (E. coli) ranging from 0.58 to 4.51 log10 CFU/mL. A total of 79 isolates of E. coli were confirmed through polymerase chain reaction (PCR) amplifying the uidA gene and were tested for phenotypic resistance using 10 antimicrobials through the Kirby–Bauer disc diffusion method. Forty-six isolates (58.22%) were noted to be multidrug resistant (MDR) with high resistance rate to cephalothin, tetracycline, streptomycin, ampicillin, trimethoprim, nalidixic acid, and chloramphenicol. Moreover, this study also examined the prevalence of Class I and II integrons accounting to 67.39% and 17.39%, respectively, of the MDR E. coli strains using multiplex PCR. The results imply that the agricultural water used in Bulacan is contaminated with the fecal material of man or other animals present in the area, and the presence of MDR bacteria, which pose a potential threat to individuals in these areas, is alarming. In addition, detection of integrons could be a good marker for the identification of MDR isolates. Lastly, this study could develop strategies for the proper management of farming sites leading to the detection of food-borne pathogens and prevention of infectious diseases.

16. Rodriguez, L. J., Young, F., Rasplus, J.-, Kjellberg, F., & Compton, S. G. (2017). Constraints on convergence: hydrophobic hind legs allow some male pollinator fig wasps early access to submerged females. Journal of Natural History, 51(13–14), 761–782.more


Pollinator fig wasps (Hymenoptera: Agaonidae) display numerous adaptations linked to their obligate association with fig trees (Ficus). Ceratosolen fig wasps pollinate figs that often fill temporarily with liquid, and one clade has males with unusually long hind legs. We investigated their morphology and behaviour. Scanning electron microscopy (SEM) revealed that the cuticle of their hind legs is highly modified and covered with numerous hydrophobic setae and microtrichia that can prevent blockage of the wasps’ large propodeal spiracles by liquids. In deep liquid, the males floated on the surface, but when only a thin layer of liquid was present, the legs allowed males to access females without the risk of drowning. Access to females was facilitated by an air bubble that forms between the hind legs and maintains a column of air between the spiracles and the centre of the figs. Sexual selection should favour males that can gain earlier access to mates, and the modified legs represent an adaptation to achieve this. Convergent adaptations are known in some unrelated non-pollinating fig wasps that develop in similar liquid-filled figs, but these species have enlarged hydrophobic peritremata at the ends of their metasoma to protect the spiracles located there. Unlike non-pollinating fig wasps, pollinator males need to insert their metasoma deep into females’ galls during mating. This difference in mating behaviour has constrained the extent of convergence.

17. Tayaban, K.M.M., Pintor, K.L., Vital, P.G. (2017). Detection of potential harmful algal bloom-causing microalgae from freshwater prawn farms in Central Luzon,Philippines, for bloom monitoring and prediction. Springer Science+Business Media Dordrecht. doi:10.1007/s10668-017-9942-8more


Prawn aquaculture industry is one of the developing economic activities in thePhilippines. Generally, a wide range of microalgae typically grow and proliferate in many aquaculture ponds. However, certain species of microalgae have the ability to form harmful algal blooms (HABs) which often bring damaging consequences to the aquaculture industry, food safety, and the environment. The study aims to identify and characterize the composition of microalgae (particularly Cyanophyta) that are capable of forming HABs in selected freshwater prawn culture ponds in Central Luzon,Philippines, using morphological, ultrastructural, and molecular characterizations. From water samples collected in ten selected ponds across Central Luzon (Bulacan, Nueva Ecija, Pampanga, Tarlac, and Zambales), potential HAB formers such as Oscillatoria agardhii, O. princeps, Microcystis aeruginosa, and M. wesenbergii were observed to have occurred mostly, while Anabaena circinalis was only observed in one site. Both morphological and ultrastructural methods brought upon some challenges and limitations while molecular methods using 16S rRNA gene and phylogenetic analysis which were optimized in this study offered better and more efficient ways of identification and were helpful in resolving genus-level and species-level relationships. The influence of physicochemical properties of pond water, especially nutrient levels (nitrate, nitrite, and orthophosphate) on the occurrence of these cyanobacteria was also analyzed. As a pioneering study on freshwater HABs in aquaculture ponds in the country, results of the study can provide information to improve the knowledge in bloom occurrence and prediction, and to develop freshwater HAB prevention and control methods. 


18. Vallejo, B., J., Conejar-Espedido, J., Manubag, L. d., Artiaga, K. C. C., Damatac, A.M., Ii., Imperial, I. C. V. J., … Cao, E. P. (2017). First record of the charru Mussel mytella charruana d’orbignyi, 1846 (Bivalvia: Mytilidae) from Manila Bay, Luzon, Philippines. BioInvasions Records, 6(1), 49–55. more


This study reports the presence of the Charru mussel Mytella charruana d'Orbignyi, 1846 (Bivalvia: Mytilidae) in Manila South Harbor, Manila Bay, Luzon Island, Philippines. In 2014, mussels previously identified as Mytilus spp. were reported in Manila Bay. The species was detected as part of an ecological dynamics study of previously-recorded marine non-indigenous mollusc species. DNA barcoding results suggest that the previously identified Mytilus are in fact Mytella charruana with an average identity match of 94%. The trends in abundance of Mytella during the 2014–2015 sampling season are described and the potential of this new species to become invasive and competitive with native Perna viridis (Linnaeus, 1758).

19. Velarde, M.C. (2017). Epidermal barrier protects against age-associated systemic inflammation. Journal of Investigative Dermatology, 137 (6), Pages 1206-1208.more


Skin provides barrier protection for the body, but aging disrupts epidermal barrier function. Hu et al. show that disruption of the epidermal barrier increases serum cytokine levels partly because of increased cytokine production by the skin. They then show that restoring epidermal barrier function in aged mice reduces circulating levels of proinflammatory cytokines.

20. Villacorta, R. B., Faith Javier Roque, K., Tapang, G. A., & Jacinto, S. D. (2017). Plant extracts as natural photosensitizers in photodynamic therapy: in vitro activity against human mammary adenocarcinoma MCF-7 cells. Asian Pacific Journal of Tropical Biomedicine, 7(4), 358–366. more



To examine three plant extracts [Lumnitzera racemosa(Combretaceae) (L. racemosa),Albizia procera(Fabaceae) (A. procera) andCananga odorata(Annonaceae)] for their potential as source of photosensitizers in photodynamic therapy.


Human mammary adenocarcinoma (MCF-7) cells were treated with the plant extracts, which were irradiated with 5.53 mW and 0.553 mW broadband light. Cell viability was assessed using MTT assay and induction of apoptosis was determined using terminal deoxynucleotidyl transferase-dUTP nick end labeling assay.


The crude ethanolic extracts, independently, were nontoxic against cancer and non-cancer cells but when irradiated with 5.53 mW broadband light,L. racemosaandA. proceraextracts were cytotoxic against MCF-7 with IC50of 11.63 μg/mL and 10.73 μg/mL, respectively. With 0.553 mW broadband light, the IC50values were higher at 17.14 μg/mL and 19.59 μg/mL, respectively. PhotoactivatedL. racemosaandA. proceraextracts were found to be more cytotoxic against MCF-7 than the non-cancer cell line, human dermal fibroblast-neonatal. Moreover, the cytotoxicity of the extracts was mediated by apoptosis.


Two of the plant extracts used,L. racemosaandA. procerawere toxic and induced apoptosis to mammary cell adenocarcinoma, MCF-7 when photoactivated. These extracts were also more toxic to human cancer than non-cancer cell lines.

21. Vital, P.G., Caballes, M.B.D., Rivera, W.L. (2017). Antimicrobial resistance in Escherichia coli and Samonella spp. isolates from fresh produce and the impact to food safety. Journal of Environmental Science and Health-Part B Pesticides, Food Contaminants, and Agricultural Wastes.


Foodborne diseases associated with fresh produce consumption have escalated worldwide, causing microbial safety of produce of critical importance. Bacteria that have increasingly been detected in fresh produce are Escherichia coli and Salmonella spp., both of which have been shown to progressively display antimicrobial resistance. The study focused on the assessment of antimicrobial resistance of these enteric bacteria from different kinds of fresh produce from various open air markets and supermarkets in the Philippines. Using the disk diffusion assay on a total of 50 bacterial isolates obtained from 410 fresh produce surveyed, monoresistance to tetracycline was observed to be the most prevalent (38%), followed by multidrug resistance to tetracycline, chloramphenicol, ciprofloxacin, and nalidixic acid (4%), and lastly by dual resistance to tetracycline and chloramphenicol (2%). Using multiplex and simplex polymerase chain reaction (PCR) assays, tetA (75%) and tetB (9%) were found in tetracycline resistant isolates, whereas catI (67%) and catIII (33%) were detected in chloramphenicol resistant isolates. Sequence analysis of gyr and par genes from the ciprofloxacin and nalidixic acid resistant isolates revealed different mutations. Based on the results, fresh produce act as a reservoir of these antibiotic resistant bacteria which may pose health threat to consumers. 

22. Vital, P. G., Van Ha, N. T., Tuyet, L. T., & Widmer, K. W. (2017). Application of quantitative real-time PCR compared to filtration methods for the enumeration of Escherichia coli in surface waters within Vietnam. Journal of Water and Health, 15(1), 155–162. more


Surface water samples in Vietnam were collected from the Saigon River, rural and suburban canals, and urban runoff canals in Ho Chi Minh City, Vietnam, and were processed to enumerate Escherichia coli. Quantification was done through membrane filtration and quantitative real-time polymerase chain reaction (PCR). Mean log colony-forming unit (CFU)/100 ml E. coli counts in the dry season for river/suburban canals and urban canals were log 2.8 and 3.7, respectively, using a membrane filtration method, while using Taqman quantitative real-time PCR they were log 2.4 and 2.8 for river/suburban canals and urban canals, respectively. For the wet season, data determined by the membrane filtration method in river/suburban canals and urban canals samples had mean counts of log 3.7 and 4.1, respectively. While mean log CFU/100 ml counts in the wet season using quantitative PCR were log 3 and 2, respectively. Additionally, the urban canal samples were significantly lower than those determined by conventional culture methods for the wet season. These results show that while quantitative real-time PCR can be used to determine levels of fecal indicator bacteria in surface waters, there are some limitations to its application and it may be impacted by sources of runoff based on surveyed samples.

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1. Atayde, E. C., Jr., Berenguel, M. M., & Arco, S. D. (2017). RAFT Polymerization of Dual Responsive Hyperbranched-Star Copolymers of Methacrylic Acid and Poly(Ethylene Glycol). Materials Science Forum, 890. Pages 78-81. doi:10.4028/ more


Smart polymers are materials that respond to external stimuli via reversible morphological changes, making them potential systems for drug delivery applications. In this study, dualresponsive star copolymers with a hyperbranched core composed of ethylene glycol dimethacrylate (EGDMA) - methacrylic acid (MAA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA) arms were synthesized via two-step Reversible Addition-fragmentation Chain Transfer (RAFT) block copolymerization. The synthesis involved the formation of the hyperbranched MAA core followed by arm extension with PEGMA. The formation of the hyperbranched core and subsequent copolymerization with PEGMA were verified by FT-IR and 1H-NMR spectroscopic techniques. The distinct EGDMA peak was found at 4.3 ppm while the peak attributed to PEGMA was found at around 3.5 ppm. Furthermore, the synthesized block copolymers were both temperature and pH-responsive with LCST value at 57ºC and morphological transition at pH 5.6. The synthesized smart polymer was also biocompatible based on Trypan blue cytotoxicity assay. The inherent dual responsive behavior and biocompatibility of the copolymer render it a good candidate for drug delivery systems.  

2. Austria, E.S., Jr., Fuentes, E.M., Nuesca, G.M., Lamorena, R.B. (2017). Laser-induced breakdown spectroscopy for the quantitative analysis of metals in sediments using natural zeolite matrix. Spectrochimica Acta - Part B Atomic Spectroscopy, 136, Pages 1-7.more


The dependence of laser-induced breakdown spectroscopy (LIBS) to the matrix of the sample remains an important consideration in performing quantitative analysis. In this study, a new matrix was introduced in the preparation of solid powder calibration curves. Heat-treated natural zeolite and KBr were mixed separately into high purity metal powders to generate calibration curves using a univariate approach. A LIBS technique was used in the detection and quantitative analysis of Cr, Cu and Pb in river sediment samples. The relative percent difference (RPD) was calculated to describe the variability measurements made using ICP/OES and LIBS as well as to evaluate the accuracy of the method. Calculated limits of detection in the matrices prepared were comparable with literature values and ranged from 0.41 to 6.1 ppm. The resulting metal concentrations indicate that the natural zeolite matrix were closer to the reference values compared to the KBr matrix. By employing principal component analysis (PCA), heat treated zeolite was shown as a potential diluent or binder for generating calibration curves and could provide matrix-matched standards in identification of target metals from unknown sediment samples. The natural zeolite appeared to closely simulate the ablation behavior and property of the samples, and it is found to be a potential suitable matrix for the quantitative LIBS analysis of sediments.

3. Edanõl, Y. D. G., Ferrer, M. R. R., Raguindin, R. K. M., & Arco, S. D. (2016). Potentiometric determination of a regulated veterinary drug via MIP-modified electrodeProceedings of the 3rd International Conference on Biomedical and Bioinformatics Engineering, Pages 71-74. doi>10.1145/3022702.3022723.more


Potentiometric sensor based on a molecularly imprinted polymer was fabricated for the detection of chloramphenicol (CAP), a broad spectrum antibiotic which is regulated by the government due to its toxicity at high doses, adverse effects and suspected carcinogenicity. The molecularly imprinted polymer for chloramphenicol (MIP-CAP) was prepared via precipitation polymerization with MAA as the functional monomer, EGDMA as cross-linker, and CAP as template. UV-Vis and FT-IR spectroscopy were used to confirm the synthesis of the MIP. The MIP has a binding capacity of 27.827±1.267 mg CAP per gram MIP. Potentiometric measurements revealed a response of 57.85 mV/decade at the linear range of 10-5 to 10-3 M at the working pH 7.4. The limit of detection for the electrode was 7.639x10-6 M or 2.42 ppm. Response of the MIP and the MIP-modified electrode against structural analogues of CAP were also investigated.

4. Hubilla, F. A. D., Mabilangan, A. I., Advincula, R. C., & Del Mundo, F. R. (2017). A surface plasmon resonance histamine sensor based on an electropolymerized molecularly imprinted polymer (E-MIP). MATEC Web of Conferences, 95. doi:10.1051/matecconf/20179502006.more


In this paper, histamine sensing by surface plasmon resonance (SPR) spectroscopy using an electropolymerized molecularly imprinted polymer (E-MIP) of functionalized polyterthiophene and histamine is reported. The MIP histamine sensor showed good linear relationship (R2 = 0.995) between the SPR angle shift and the logarithm of histamine concentration, ranging from 15-500 μg/mL, with a limit of detection (LOD) of 2.0 μg/mL and a calibration sensitivity of 44.6 m° per log μg/mL histamine. Results also showed higher binding affinity of histamine for the MIP sensor than for the non-imprinted (NIP) sensor indicating excellent specificity. Moreover, the selectivity of the MIP histamine sensor against some of its structural analogues was demonstrated.

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1. Aragones, L. V., Laggui, H. L., & Amor, A. K. (2017). The Philippine Marine Mammal Strandings from 2005 to 2016. A PMMSN Publication. Technical Report No. 1.

2. Bagtasa, G. (2017). Contribution of tropical cyclones to rainfall in the Philippines. Journal of Climate, 30(10), 3621–3633. 

3. Bondoc, J.L., Aragones, L.V., Masangkay, J.S. (2017). Hematological, macroscopic and microscopic findings in two stranded whales (Mesoplodon densirostris and Kogia sima) and possible causes of deaths. Philippine Journal of Veterinary Medicine, 54 (1), Pages 64-71. more


Stranded marine mammals may serve as opportunities for probing scientific queries. This study subjected formalin-fixed tissues of two cetaceans, Mesoplodon densirostris (Blainville's beaked whale) and Kogia sima (dwarf sperm whale), found stranded in Region 11 (Davao) of the Philippines between April and July 2014 to histopathological examination following necropsy and hematological evaluations. Lesions observed in 2 of 2 animals (100%) were congested hepatic sinusoids, hemorrhages, hemosiderosis, parasitic disease and pulmonary edema. Other lesions (1 of 2, 50%) were seen in the gastrointestinal tract (congestion, Lieberkhun mononuclear cell infiltrations, villi blunting and adhesion), kidney (blood sludging, membranous glomerulopathy, tubular cell atrophy) and lungs (fungal granuloma, pneumonia). M. densirostris showed severe iron deficiency and thrombocytopenia but with lymphocytosis. K. sima revealed low white blood cell count and neutropenia but with thrombocytosis and hemoconcentration. This study suggests that systemic infection for both animals with membranous glomerulopathy and endoparasitism-associated pneumonia (in M. densirostris) and microthrombi formation (in K. sima) were the major causes of their deaths. Presented results, however limited, may serve as baseline data underpinning cetacean clinicopathological research in the Philippines.

4. Comiso, J.C., Gersten, R.A., Stock, L.V., Turner, J., Perez, G.J., Cho, K. (2017). Positive Trend in the Antarctic Sea Ice Cover and Associated Changes in Surface Temperature. American Meteorological Society.


The Antarctic sea ice extent has been slowly increasing contrary to expected trends due to global warming and results from coupled climate models. After a record high extent in 2012 the extent was even higher in 2014 when the magnitude exceeded 20 × 106 km2 for the first time during the satellite era. The positive trend is confirmed with newly reprocessed sea ice data that addressed inconsistency issues in the time series. The variability in sea ice extent and ice area was studied alongside surface ice temperature for the 34-yr period starting in 1981, and the results of the analysis show a strong correlation of −0.94 during the growth season and −0.86 during the melt season. The correlation coefficients are even stronger with a one-month lag in surface temperature at −0.96 during the growth season and −0.98 during the melt season, suggesting that the trend in sea ice cover is strongly influenced by the trend in surface temperature. The correlation with atmospheric circulation as represented by the southern annular mode (SAM) index appears to be relatively weak. A case study comparing the record high in 2014 with a relatively low ice extent in 2015 also shows strong sensitivity to changes in surface temperature. The results suggest that the positive trend is a consequence of the spatial variability of global trends in surface temperature and that the ability of current climate models to forecast sea ice trend can be improved through better performance in reproducing observed surface temperatures in the Antarctic region.

5. Gibe, H.P., Cayetano, M.G. (2017). Spatial estimation of air PM2.5 emissions using activity data, local emission factors and land cover derived from satellite imagery. Atmospheric measurement techniques, (10), Pages 3313-3323.


Exposure to particulate matter (PM) is a serious environmental problem in many urban areas on Earth. In the Philippines, most existing studies and emission inventories have mainly focused on point and mobile sources, while research involving human exposures to particulate pollutants is rare. This paper presents a method for estimating the amount of fine particulate (PM2.5) emissions in a test study site in the city of Cabanatuan, Nueva Ecija, in the Philippines, by utilizing local emission factors, regionally procured data, and land cover/land use (activity data) interpreted from satellite imagery. Geographic information system (GIS) software was used to map the estimated emissions in the study area. The present results suggest that vehicular emissions from motorcycles and tricycles, as well as fuels used by households (charcoal) and burning of agricultural waste, largely contribute to PM2.5 emissions in Cabanatuan. Overall, the method used in this study can be applied in other small urbanizing cities, as long as on-site specific activity, emission factor, and satellite-imaged land cover data are available.


6. Ringor, C.L., Pascua, C.S., Villanueva, J.C.B., Garcia, A.K.H., Agulo, I.J.A., Matsushita, Y., Miyazawa, K. (2017). Multiwalled carbon nanofibers and nanocapsules synthesized from plant oil via atmospheric CVD process. Journal of Nanoscience and Nanotechnology, 17 (5), Pages 3543-3550. more


Calophyllum inophyllum (CI) oil was used as precursor source material in carbon nanomaterial synthesis. CI is a non-edible and native plant species in the Philippines, which makes production of seeds and kernel sustainable. An atmospheric pressure chemical vapor deposition system was designed and built for the synthesis. Different carbon-based nanostructures were synthesized by varying the Argon gas flow rates (3.5–5 liter/min) and temperatures (1000–1200 °C). Crystalline multiwalled nanofibers and iron carbide-encapsulated nanocapsules were formed at 1000 °C and a gas flow rate of 5 liter/min. On the other hand, oils synthesized at 1100–1200 °C produced amorphous film-like carbon materials. The different morphologies reflect the influence of the gas flow rate on the dilution and atomization of the oil and its decomposition at various temperatures used. Raman spectroscopy and surface potential measurements indicate the potential applications of these nanofibers for hydrogen storage and semiconducting devices.

7. Rollon, R.N., Villamayor, B.M.R., Oropesa, L.J.B., and Samson, M.S. (2017). Prop root production response of planted Rhizophora to abrupt subsidence-induced sea level rise. Ocean and Coastal Management, 142, Pages 198-208. more


The 7.2 Mw Bohol earthquake in 2013 caused significant ground subsidence in some coastal zones northwest of the province, shifting the tidal inundation regime of intertidal habitats. These habitats included more than 500 ha of mangrove plantations particularly in island barangays which substrates are now 85% inundated annually from the 40% pre-quake conditions. Consequently, in less than three years after the quake, the effort of the subsided individual trees to produce new prop roots above the pre-quake height limits was found to be immediate, substantial, and tidally-linked. This prop root response resulted in an increase in the total length and volume by 74% and 39%, respectively, at 2.5-year post-quake relative to the 20-year pre-quake cumulative. With a mean elongation rate of ca. 1.1 m y−1, some 1.5–2.2 year period was necessary for these new prop roots to reach the substrate, and effectively establish a new equilibrium. The results highlight the role of prop roots on the aeration and stability requirements of Rhizophora, and provide quantitative evidence against the common practice of harvesting prop roots for firewood, charcoal, and other various purposes. The study presents a short-term glimpse of the prop root response of Rhizophora to the otherwise long-term gradual process of sea level rise.

8. Vallejo, B., Jr., Conejar-Espedido, J., Manubag, L., Artiaga, K.C.C., Damatac, A.M., II, Imperial, I.C.V.J., Itong, T.A.B., Fontanilla, I.K., Cao, E.P. (2017). First record of the Charru mussel Mytella charruana d’Orbignyi, 1846 (Bivalvia: Mytilidae) from Manila Bay, Luzon, Philippines. BioInvasions Records, 6 (1), Pages 49-55. more


This study reports the presence of the Charru mussel Mytella charruana d’Orbignyi, 1846 (Bivalvia: Mytilidae) in Manila South Harbor, Manila Bay, Luzon Island, Philippines. In 2014, mussels previously identified as Mytilus spp. were reported in Manila Bay. The species was detected as part of an ecological dynamics study of previously-recorded marine non-indigenous mollusc species. DNA barcoding results suggest that the previously identified Mytilus are in fact Mytella charruana with an average identity match of 94%. The trends in abundance of Mytella during the 2014–2015 sampling season are described and the potential of this new species to become invasive and competitive with native Perna viridis (Linnaeus, 1758)

9. Vergara, R.L., Macalalad, E.P., Bagtasa, G., Vallar, E.A., Galvez, M.C.D., Francisco, R.V. (2017). Correlation of aerosol optical properties with surface meteorological parameters over ManilaAdvance Science Letters, 23 (2), Pages 1448-1451.  more


Aerosol optical properties such as aerosol optical depth (AOD) at 500 nm together with wavelength exponent (α) and Ångstrom turbidity coefficient (β) obtained from a sunphotometer over Manila were used to analyze their response to the changes in temperature, relative humidity (RH) and zonal wind. Data retrieved for a one year period of measurements (August 2009–July 2010) were used to describe the variations of the aerosol optical properties. Temperature showed weak correlations with the aerosol optical properties. Surface RH confirmed evidence for its influence on aerosols size distribution and dominant aerosol type. Zonal wind demonstrated influences on the prevailing aerosol present at a certain area and caused alteration the amount of its loading.


1. Akiyama, S., & Caalim, J. (2017). Invariant Measure of Rotational Beta Expansion and Tarski’s Plank Problem. Discrete & Computational Geometry, 57(2), Pages 357–370.more


We study the invariant measures of a piecewise expanding map in RmRm defined by an expanding similitude modulo a lattice. Using the result of Bang (Proc Am Math Soc 2:990–993, 1951) on the plank problem of Tarski, we show that when the similarity ratio is at least m+1m+1, the map has an absolutely continuous invariant measure equivalent to the m-dimensional Lebesgue measure, under some mild assumption on the fundamental domain. Applying the method to the case m=2m=2, we obtain an alternative proof of the result in Akiyama and Caalim (J Math Soc Japan 69:1–19, 2016) together with some improvement.

2. Akiyama, S.  & Caalim, J. (2017). Rotational beta expansion: Ergodicity and soficness. Journal of the Mathematical Society of Japan, 69(1), 397–415. more


We study a family of piecewise expanding maps on the plane, generated by composition of a rotation and an expansive similitude of expansion constant β. We give two constants B1and B2 depending only on the fundamental domain that if β > B1 then the expanding map has a unique absolutely continuous invariant probability measure, and if β > B2 then it is equivalent to 2-dimensional Lebesgue measure. Restricting to a rotation generated by q-th root of unity ζ with all parameters in ℚ(ζ,β), the map gives rise to a sofic system when cos(2π/q) ℚ(β) and β is a Pisot number. It is also shown that the condition cos(2π/q) ℚ(β) is necessary by giving a family of non-sofic systems for q = 5.

3. Arceo, C. P. P., Jose, E. C., Lao, A. R., & Mendoza, E. R. (2017). Reaction networks and kinetics of biochemical systems. Mathematical Biosciences, 283, Pages 13–29.more


This paper further develops the connection between Chemical Reaction Network Theory (CRNT) and Biochemical Systems Theory (BST) that we recently introduced [1]. We first use algebraic properties of kinetic sets to study the set of complex factorizable kinetics CFK(N) on a CRN, which shares many characteristics with its subset of mass action kinetics. In particular, we extend the Theorem of Feinberg-Horn [9] on the coincidence of the kinetic and stoichiometric subsets of a mass action system to CF kinetics, using the concept of span surjectivity. We also introduce the branching type of a network, which determines the availability of kinetics on it and allows us to characterize the networks for which all kinetics are complex factorizable: A “Kinetics Landscape” provides an overview of kinetics sets, their algebraic properties and containment relationships. We then apply our results and those (of other CRNT researchers) reviewed in [1] to fifteen BST models of complex biological systems and discover novel network and kinetic properties that so far have not been widely studied in CRNT. In our view, these findings show an important benefit of connecting CRNT and BST modeling efforts.


4. Calderon, P. G. B., Habib, M., Kappel, F., & Reyes V, A. A. de los. (2017). Control aspects of the human cardiovascular-respiratory system under a nonconstant workload. Mathematical Biosciences, 289, 142–152.more


The human cardiovascular system (CVS) and respiratory system (RS) work together in order to supply oxygen (O2) and other substrates needed for metabolism and to remove carbon dioxide (CO2). Global and local control mechanisms act on the CVS in order to adjust blood flow to the different parts of the body. This, in turn, affects the RS since the amount of O2 and CO2 transported, respectively to and away from the tissues depends on the cardiac output and blood flow in both the systemic and pulmonary circuits of the CVS. Local metabolic control is influenced by local concentrations of blood gases affecting systemic resistance, resulting to vasoconstriction/vasodilation. Thus, the exchange of blood gases demands a tight coordination between blood flow and ventilation of the lungs. In this work, a model of the cardiovascular-respiratory system (CVRS) is considered to obtain an optimal control for time-dependent ergometric workloads by using the Euler-Lagrange formulation of the optimal control problem. The essential controls in the CVRS model are variations in the heart rate and alveolar ventilation through which the central nervous system restricts the arterial partial pressure of CO2 (Pa,CO2) close to 40  mmHg. Further, penalization terms in the cost functional are included to match the metabolic need for O2 and the metabolic production of CO2with O2- and CO2-transport by blood.

5. Celeste, R. O., Corcino, R. B., & Gonzales, K. J. M. (2017). Two approaches to normal order coefficients. Journal of Integer Sequences, 20(3). more


We consider the normal ordering coefficients of strings consisting of the symbols V, U which satisfy the commutation rule UV - qVU = hVs. These coefficients are studied using two approaches. First, we continue the study by Varvak, where the coefficients were interpreted as q-rook numbers under the row creation rook model introduced by Goldman and Haglund. Second, we express the coefficients in terms of a kind of generalization of some symmetric functions. We derive identities involving the coefficients including some explicit formulas.

6. David, G., Pedrigi, R. M., & Humphrey, J. D. (2017). Accommodation of the human lens capsule using a finite element model based on nonlinear regionally anisotropic biomembranes. Computer Methods in Biomechanics and Biomedical Engineering, 20(3), 302–307. more


Accommodation of the eyes, the mechanism that allows humans to focus their vision on near objects, naturally diminishes with age via presbyopia. People who have undergone cataract surgery, using current surgical methods and artificial lens implants, are also left without the ability to accommodate. The process of accommodation is generally well known; however the specific mechanical details have not been adequately explained due to difficulties and consequences of performing in vivo studies. Most studies have modeled the mechanics of accommodation under assumptions of a linearly elastic, isotropic, homogenous lens and lens capsule. Recent experimental and numerical studies showed that the lens capsule exhibits nonlinear elasticity and regional anisotropy. In this paper we present a numerical model of human accommodation using a membrane theory based finite element approach, incorporating recent findings on capsular properties. This study seeks to provide a novel perspective of the mechanics of accommodation. Such findings may prove significant in seeking biomedical solutions to restoring loss of visual power.

7. de la Cruz, R. J., & dela Rosa, K. (2017). Each 2n-by-2n complex symplectic matrix is a product of n+1 commutators of J-symmetries. Linear Algebra and Its Applications, 517, 53–62. more


A 2n×2n complex matrix A   is symplectic if  . If A   is symplectic and rank(A−I)=1, then it is called a J-symmetry. For each n  , we prove that every 2n×2n symplectic matrix M   is a product of n+1 commutators of J-symmetries and this number cannot be smaller for some M.

8. John, R., Cruz, D., Merino, D. I., & Paras, A. T. (2017). Every 2 n -by-2 n complex matrix is a sum of three symplectic matrices. Linear Algebra and Its Applications, 517, Pages 199–206.more


Let. AnAM2n(C)is calledsymplectic  ifATJ2nA=J2n. Ifn=1, then we show that every matrix inM2n(C)is a sum of two symplectic matrices. Ifn>1, then we show that every matrix inM2n(C)is a sum of three symplectic matrices; moreover, we show that some matrices cannot be written with less than three symplectic matrices. We also show that for everyAM2n(C), there exist symplecticP  ,QM2n(C)andB,C  ,DMn(C)such that. IfA  is skew Hamiltonian (), then we show thatAis a sum of two symplectic matrices.

9. Lope, J., & Ona, M. (2017). Solvability of a system of totally characteristic equations related to Kähler metrics. Electronic Journal of Differential Equations


We consider a system of equations composed of a higher order singular partial differential equation of totally characteristic type and several higher order non-Kowalevskian linear equations. This system is a higher order version of a system that arose in Bielawski's investigations on Kähler metrics. We first prove that this system has a unique holomorphic solution. We then show that if the coefficients of the system are in some formal Gevrey class, then the unique solution is also in the same formal Gevrey class.

10. Loquias, M. J. C., Valdez, L. D., & Walo, M. L. B. (2017). Color groups of colorings of N-planar modules. In Journal of Physics: Conference Series (Vol. 809). more


A submodule of a  -module determines a coloring of the module where each coset of the submodule is associated to a unique color. Given a submodule coloring of a  -module, the group formed by the symmetries of the module that induces a permutation of colors is referred to as the color group of the coloring. In this contribution, a method to solve for the color groups of colorings of N-planar modules where N = 4 and N = 6 are given. Examples of colorings of rectangular lattices and of the vertices of the Ammann-Beenker tiling are given to exhibit how these methods may be extended to the general case.

11. Loquias, M. J. C., Mkaouar, M., Scheicher, K., & Thuswaldner, J. M. (2017). Rational digit systems over finite fields and Christol’s Theorem. Journal of Number Theory, 171, Pages 358–390. more


LetP,QFq[X]{0}be two coprime polynomials over the finite fieldFqwithdeg⁡P>deg⁡Q. We represent each polynomialw  overFqby  im loquias

using a rationalbase  P/Qanddigits  siFq[X]satisfyingdeg⁡si<deg⁡P.Digit expansions  of this type are also defined for formal Laurent series overFq. We prove uniqueness and automatic properties of these expansions. Although theω  -language of the possible digit strings is not regular, we are able to characterize the digit expansions of algebraic elements. In particular, we give a version of Christol's Theorem by showing that the digit string of the digit expansion of a formal Laurent series is automatic if and only if the series is algebraic overFq[X]. Finally, we study relations between digit expansions of formal Laurent series and a finite fields version of Mahler's 3/2-problem.

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1. Felix, M. J., Muldera, J., Somintac, A., Salvador, A., & Estacio, E. (2017). Enhanced Terahertz emission and raman signal from silicon nanopyramids. Science of Advanced Materials, 9(2), Pages 214–219.


2. Rosete, M.M., Zosa, M.H., & Sarmago, R.V. (2017). Effect of Potassium Chloride as a Supporting Electrolyte on the Dispersion Towards the Fabrication of Films by Electrophoretic Deposition of Bi2Sr2CaCu2O8 in EthanolJournal of Superconductivity and Novel Magnetism, Pages 1-6more


Bi2Sr2CaCu2O8 (Bi-2212) powder was fabricated using solid state reaction method. The suspensions were prepared containing finely ground Bi-2212 powder with and without potassium chloride (KCl) addition. Settling experiments and measurements of zeta potential, particle size distribution, and electrophoretic mobility were performed to determine the optimal concentration of the supporting electrolyte. Bi-2212 suspensions were used in electrophoretic deposition (EPD), and the films were heat treated. The results showed that the optimal concentration of KCl is 5.21 wt %. The zeta potential at this concentration is highest at about 31.10 mV, the settling velocity is lowest ∼3.84 mm/min, and the particle size is smallest (∼450 nm), which indicate that the dispersion is better due to the reduction of intermolecular attraction. The effects of KCl as a flux were observed in the microstructure and superconducting properties of Bi-2212 film. The smoothest surface morphology, high c-axis orientation, and highest critical temperature (Tc)-onset of 84.73 K were obtained from the film prepared with optimized Bi-2212 suspension.

3. Tingzon, P., Lopez, L., Oliver, N., Cabello, N., Cafe, A., De Los Reyes, A., … Somintac, A. (2017). Terahertz emission and photoluminescence of Silicon Nanowires electrolessly etched on the surface of Silicon (100), (110), and (111) substrates for photovoltaic cell applications. Photonics and Nanostructures - Fundamentals and Applications, 24, 1–6. 


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1. Abesamis, R. A., Berumen, P. S. M. L., Bode, M., Renato, C., Leilani, L. J., Cesar, A. S., … Garry, C. A. (2017). Reef-fish larval dispersal patterns validate no-take marine reserve network connectivity that links human communities. Coral Reefs, Pages 1–11. 

2. Atrigenio, M., Aliño, P., & Conaco, C. (2017). Influence of the Blue Coral Heliopora coerulea on Scleractinian Coral Larval Recruitment. Journal of Marine Biology

3. Billones, J. B. a., Carrillo, M. C. O. ., Organo, V. G., Sy, J. B. A., Clavio, N. A. B., Macalino, S. J. Y., … Concepcion, G. P. (2017). In silico discovery and in vitro activity of inhibitors against Mycobacterium tuberculosis 7,8-diaminopelargonic acid synthase (Mtb BioA). Drug Design, Development and Therapy, 11, Pages 563–574. 

4. Cabaitan, P. C., & Conaco, C. (2017). Bringing back the giants: juvenile Tridacna gigas from natural spawning of restocked giant clams. Coral Reefs

5. Da-Anoy, J. P., Villanueva, R. D., Cabaitan, P. C., & Conaco, C. (2017). Effects of coral extracts on survivorship, swimming behavior, and settlement of Pocillopora damicornis larvaeJournal of Experimental Marine Biology and Ecology486, Pages 93–97.

6. Dumilag, R. V., & Aguinaldo, Z.-Z. A. (2017). Genetic differentiation and distribution of Pyropia acanthophora (Bangiales, Rhodophyta) in the PhilippinesEuropean Journal of Phycology0(0), Pages 1–12.

7. Gajigan, A. P., & Conaco, C. (2017). A microRNA regulates the response of corals to thermal stress. Molecular Ecology

8. Jamodiong, E. A., Maboloc, E. A., Leriorato, J. C., Talledo, M. C. S., Diaz, L. A., Tabalanza, T. D., … Villanueva, R. D. (2017). Coral spawning and spawn-slick observation in the Philippines. Marine Biodiversity, Pages 1–6. 

9. Mizuno, K. ., Asada, A. ., Matsumoto, Y. ., Sugimoto, K. ., Fujii, T. ., Yamamuro, M. ., … Jimenez, L. A. (2017). A simple and efficient method for making a high-resolution seagrass map and quanti fi cation of dugong feeding trail distribution : A field test at the Mayo Bay, Philippines. Ecological Informatics, 38, Pages 89–94.

10. Morimoto, N., Umezawa, Y., San Diego-McGlone, M. L., Watanabe, A., Siringan, F. P., Tanaka, Y., … Miyajima, T. (2017). Spatial dietary shift in bivalves from embayment with river discharge and mariculture activities to outer seagrass beds in northwestern Philippines. Marine Biology, 164(4), Pages 1–16.

11. Naval, P.C., J., & David, L. (2017). FishDrop: Estimation of reef fish population density and biomass using stereo cameras. In Techno-Ocean 2016: Return to the Oceans. Pages 527–531. 

12. Noblezada, M. M., Miyamoto, H., Campos, W. L., Yusoff, F. M., & Nishida, S. (2017). Phylogeography of the planktonic shrimp Lucifer hanseni Nobili 1905 in the Indo-Malayan ArchipelagoJournal of the Marine Biological Association of the United Kingdom97(1), Pages 129–140.

13. Palomar-Abesamis, N., Abesamis, R. A., & Juinio-Menez, M. A. (2017). Distribution and microhabitat associations of the juveniles of a high-value sea cucumber, Stichopus cf. horrens, in northern Philippines. Aquatic Ecology, Pages 1–15. 

14. Quiros, T. E. A. L., Croll, D., Tershy, B., Fortes, M. D., & Raimondi, P. (2017). Land use is a better predictor of tropical seagrass condition than marine protection. Biological Conservation, 209, Pages 454–463. 

15. Ramos, R. D., Goodkin, N. F., Siringan, F. P., & Hughen, K. (2017). Diploastrea heliopora Sr/Ca and δ 18 O records from northeast Luzon, Philippines: an assessment of inter-species coral proxy calibrations and climate controls of sea surface temperature and salinity. Paleoceanography, Pages 424–438. 

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1. Aurelio, M. A., Dianala, J.D.B., Taguibao, K.J.L., Pastoriza, L.R., Reyes, K., Sarande, R., Lucero, A. Jr. (2017). Seismotectonics of the 6 February 2012 Mw6.7 Negros earthquake, central Philippines. Journal of Asian Earth Sciences 142(2017), Pages 93-108.more


At 03:49 UTC on the 6th of February 2012, Negros Island in the Visayan region of central Philippines was struck by a magnitude Mw 6.7 earthquake causing deaths of over 50 people and tremendous infrastructure damage leaving hundreds of families homeless. The epicenter was located in the vicinity of the eastern coastal towns of La Libertad and Tayasan of the Province of Negros Oriental. Earthquake-induced surface deformation was mostly in the form of landslides, liquefaction, ground settlement, subsidence and lateral spread. There were no clear indications of a fault surface rupture. The earthquake was triggered by a fault that has not been previously recognized. Earthquake data, including epicentral and hypocentral distributions of main shock and aftershocks, and focal mechanism solutions of the main shock and major aftershocks, indicate a northeast striking, northwest dipping nodal plane with a reverse fault mechanism. Offshore seismic profiles in the Tañon Strait between the islands of Negros and Cebu show a northwest dipping reverse fault consistent in location, geometry and mechanism with the nodal plane calculated from earthquake data. The earthquake generator is here proposed to be named the Negros Oriental Thrust (NOT). Geologic transects established from structural traverses across the earthquake region reveal an east-verging fold-thrust system. In the latitude of Guihulngan, this fold-thrust system is represented by the Razor Back Anticline – Negros Oriental Thrust pair, and by the Pamplona Anticline – Yupisan Thrust pair in the latitude of Dumaguete to the south. Together, these active fold-thrust systems are causing active deformation of the western section of the Visayan Sea Basin under a compressional tectonic regime. This finding contradicts previous tectonic models that interpret the Tañon Strait as a graben, bounded on both sides by normal faults supposedly operating under an extensional regime. The Negros Earthquake and the active fold-thrust systems that were discovered in the course of the structural analysis provide strong arguments for basin inversion processes now affecting the Visayan Sea Basin, albeit under very slow strain rates derived from previous GPS campaigns. The occurrence of the earthquake in an area where no active faults have been previously recognized and characterized by slow present-day strain rates underscores the necessity of paying more attention to and exerting more effort in the evaluation of earthquake hazards of regions that are seemingly seismically quiet, especially when they underlie highly urbanized areas.

2. Guotana, J. M. R., Payot, B. D., Dimalanta, C. B., Ramos, N. T., Faustino-Eslava, D.V., Queaño, K. L. & Yumul, G. P. Jr. (2017). Petrological and geochemical characteristics of the Samar Ophiolite ultramafic section: implications on the origins of the ophiolites in Samar and Leyte islands, Philippines. International Geology Review, Pages 1-17. (Article in Press) more


Cretaceous ophiolites and ophiolitic fragments occur in the Samar and Leyte islands in eastern central Philippines. The Samar Ophiolite is a complete crust–mantle sequence exposed in southern Samar, whereas the Tacloban and Malitbog ophiolite complexes are, respectively, located in the northeastern and southwestern portions of the nearby Leyte island. Despite the close proximity of these islands, the genetic relationship of these ophiolites and ophiolitic complexes, if any, remains to be elucidated. We present here new petrographic and geochemical data on the harzburgites and dunites of the ultramafic section of the Samar Ophiolite. These mantle peridotites are highly depleted residues which have low modal pyroxene content, high spinel Cr# (=0.62–0.79), and slightly enriched light rare earth element abundance with depletion in Zr and Ti. Such characteristics are typical of supra-subduction zone peridotites and strongly contrast with the abyssal signatures of the Tacloban and Malitbog ophiolite complexes. The absence of a structure between these adjacent ophiolite fragments initially hints that they form a single oceanic crust. However, with our new results, we suggest other possible mechanisms that could explain the relationship of these ophiolites.

3. Jago-on, K. A. B.,  Siringan, F. P., Balangue-Tarriela, R., Taniguchi, M., Reyes, Y. K., Lloren, R., Peña, M. a., Bagalihog, E.  (2017). Hot spring resort development in Laguna Province, Philippines: Challenges in water use regulation. Journal of Hydrology Regional Studies, 11, Pages 96-106.more


Study region

Calamba and Los Baños in Laguna Province, Philippines lie between the northern part of Mt. Makiling and north shore of Laguna de Bay.

Study focus

One significant activity in Laguna province is the development of the water resorts which includes hot springs resorts and spas. Presence of hot springs is due to the geothermal activities in the area. This study seeks to explore the nature and possible impacts of groundwater utilization in hot spring resorts in Calamba and Los Baños in Laguna Province. This study also analyzes the issues and challenges in the implementation of policies and laws to regulate water use in these resorts.

New hydrological insights for the region

These water resorts are estimated to consume large volume of groundwater which could result to over-extraction and decrease in groundwater quantity. However, monitoring and regulation of usage is difficult as most of these resorts operate without water use permits. If groundwater use is left unregulated, water availability for the resorts industry and for domestic, commercial and other uses in the future will be negatively affected. It is necessary to strengthen implementation of laws and enhance partnerships among national and local government agencies, private sector, civil society and communities, in the proper monitoring and regulation of groundwater resources to promote sustainability.

4. Knittel, U., Walia, M., Suzuki, S., Dimalanta, C. B., Tamayo, R., Yang, T. F., & Yumul, G. P. (2017). Diverse protolith ages for the Mindoro and Romblon Metamorphics (Philippines): Evidence from single zircon U-Pb dating. Island Arc, 26(1), e12160.more


Within the north-eastern part of the Palawan Continental Terrane, which forms the south-western part of the Philippine archipelago, several metamorphic complexes are exposed that are considered to be rifted parts of the Asian margin in South-East China. The protolith age(s) and correlations of these complexes are contentious. The largest metamorphic complex of the Palawan Continental Terrane comprises the Mindoro Metamorphics. The north-eastern part of this metamorphic complex has recently been found to be composed of protoliths of Late Carboniferous to Late Permian protolith age. However, meta-sediments exposed at the westernmost tip and close to the southern boundary of the exposure of the Mindoro Metamorphics contain detrital zircons and with U–Pb ages, determined by LA–ICP–MS, in the range 22–56 Ma. In addition, zircons as young as 112 Ma were found in a sample of the Romblon Metamorphics in Tablas. As the youngest detrital zircons provide an upper age limit for the time of deposition in meta-sediments, these results suggest that the Mindoro and Romblon Metamorphics comprise protoliths of variable age: Late Carboniferous to Late Permian in NE Mindoro; Eocene or later in NW Mindoro; Miocene at the southern margin of the Mindoro metamorphics; and Cretaceous or later on Tablas. The presence of non-metamorphic sediments of Late Eocene to Early Oligocene age in Mindoro (Lasala Formation), which are older than the youngest metasediments, suggests that metamorphism of the young meta-sediments of Mindoro is the result of the collision of the Palawan Continental terrane with the Philippine Mobile Belt in Late Miocene. Similarities of the age spectra of zircons from the Eocene to Miocene metamorphics with the Eocene to Early Miocene Lasala Formation suggest that the protoliths of the young metamorphics may be equivalents of the Lasala Formation or were recycled from the Lasala Formation.

5. Li, H., Sun, H.-S., Wu, J.-H., Evans, N. J., Xi, X.-S., Peng, N.-L., … Gabo-Ratio, J. A. S. (2017). Re–Os and U–Pb geochronology of the Shazigou Mo polymetallic ore field, Inner Mongolia: Implications for Permian–Triassic mineralization at the northern margin of the North China Craton. Ore Geology Reviews, 83, Pages 287–299.more


The recently discovered polymetallic Shazigou Mo–W–Pb–Zn ore field is located at the northern margin of the North China Craton. This integrated metallogenic system is comprised of quartz vein mineralization in three deposits: Shazigou Mo–W, Jindouzishan Pb–Zn and Mantougou Pb–Zn. The total reserves are estimated to be 50 kt Mo, 626 t WO3, 244 kt Pb and 150 kt Zn. Molybdenite Re–Os dating of five quartz vein-type ores yielded a mean model age of 243.8 ± 1.6 Ma (MSWD = 0.81) and hydrothermal zircons yielded a concordant U–Pb age of 245 ± 2.6 Ma (MSWD = 0.65). These results suggest that the mineralization was formed in the early Triassic and could be related to Paleo-Asian Ocean subduction. Microthermometry and quartz fluid inclusion compositions indicate that fluids related to the Mo–W mineralization were mainly derived from magmatic sources and precipitated under relatively high temperature (280–340 °C) and salinity conditions (6–9 wt% NaCl equiv.), whereas subsequent Pb–Zn mineralization-related fluids may have been modified by metamorphic and meteoric waters. The discovery of the Shazigou ore field suggests conditions may be favourable for more extensive mineralization in the western Xilamulun Mo metallogenic belt at the northern margin of the North China Craton.

6. Pacle, N.A.D., Dimlanta, C. B., Ramos, N. t., Payot, B. D., Faustino-Eslava, D. V., Queaño, K.L., Yumul, G. P. Jr. (2017). Petrography and geochemistry of Cenozoic sedimentary sequences of the southern Samar Island Philippines: clues to the unroofing history of an ancient subduction zone. Journal of Asian Earth Sciences, 142 (2017), Pages 3-19.more


The Cenozoic sedimentary sequences of southern Samar Island in eastern Philippines were examined to understand the unroofing history of an ancient arc terrane. Petrographic and geochemical data revealed varying degrees of inputs from the ophiolite basement and differences in modal compositions. The sedimentary units are mostly made up of lithic fragments. The Late Oligocene to Early Miocene Daram Formation contains more chert and volcanic fragments whereas the late Middle Miocene to Early Pliocene Catbalogan Formation is dominantly composed of ultramafic components. These variances are correspondingly reflected in the geochemical signatures of these two sedimentary formations. The Catbalogan Formation clastic rocks have higher volatile-free MgO and Fe2O3 values (average: 8.4% for both oxides) compared to the Daram Formation samples (average: 5.1 and 6.3%, respectively). Geochemical variations are also reflected in the Co, Cr and Ni values: the Catbalogan Formation samples reflect higher concentrations (Co: 15–57 ppm; Cr: 231–1094 ppm; Ni: 84–484 ppm) compared to the Daram Formation samples (Co: 24–32 ppm; Cr: 234–418 ppm; Ni: 212–323 ppm). These observations suggest that the Daram Formation eroded and transported more of the crustal portions of the ophiolite, while the younger Catbalogan Formation represents a later exhumation and subsequent erosion of the ultramafic section. An oceanic island arc (OIA) setting is proposed for the two formations based on several tectonic discrimination diagrams (e.g., Th-La-Sc, La vs. Th). The OIA signature is further supported by their smooth chondrite-normalized rare earth element (REE) patterns with no obvious Eu anomaly as well as LREE enrichment which are typical of sediments deposited in OIA setting. Based on the dominantly ophiolitic provenance of the Daram and Catbalogan formations, the post-emplacement history of the nearby Samar Ophiolite is constrained during the Late Oligocene to Early Pliocene period.


7. Queaño, K. L., Dimalanta, C. B., Yumul, G. P. Jr., Marquez, E. J., Faustino-Eslava, D.V., Suzuki, S., Ishida, K. (2017). Stratigraphic units overlying the Zambales Ophiolite Complex (ZOC) in Luzon, (Philippines): tectonostratigraphic significance and regional implications. Journal of Asian Earth Sciences, 142 (2017), Pages 20-31.more


The Zambales Ophiolite Complex (ZOC) on the island of Luzon, Philippines is one of the most well-studied crust-mantle sequences in the region. Several massifs comprise the ZOC, one of which is the Coto Block overlain by clastic sedimentary units previously dated as Eocene. Geochronologic studies from diabase, granodiorites and other late-stage magmatic products similarly yielded the same age. Succeeding tectonic models have therefore all been grounded on the assumption that the entire ZOC is Eocene.

Recent investigations, however, revealed the presence of chert blocks within the Early to Middle Miocene clastic formation overlying the Acoje Block in the northern part of the ophiolite complex. Radiolarians extracted from the cherts yielded a stratigraphic range that suggests a Late Jurassic to Early Cretaceous age. The recognition of a much older age than previously reported of the ZOC warrants a re-examination of its actual distribution and genesis. Correlating with other similarly-aged ophiolites, we suggest defining a western Mesozoic ophiolite belt, largely extending from the west-central portion of the archipelago to the northeastern tip of Luzon island. Tentatively, we attribute the Mesozoic ophiolitic and associated rocks in western Luzon to an arc-continent collision involving the Philippine Mobile Belt and the Palawan Microcontinental Block.

In addition, differences in the clastic compositions of the Cenozoic sedimentary formations provide material not only for deciphering the ZOC’s unroofing history but also for constraining the timing of province linkage. The intermittent appearance of lithic fragments and detrital minerals from the ophiolite in the units of the Middle Miocene Candelaria Limestone and the Late Miocene to Early Pliocene Sta. Cruz Formation indicates significant but geographically variable contributions from the ophiolite complex. In the northern Zambales Range, the Sta. Cruz Formation caps the Coto Block and the Acoje Block of the ZOC, providing a minimum age for their amalgamation.


8. Ramos, N. T., Maxwell, K. V., Tsutsumi, H., Chou, Y.-C., Duan, F., Shen, C.-C., & Satake, K. (2017). Occurrence of 1 ka-old corals on an uplifted reef terrace in west Luzon, Philippines: Implications for a prehistoric extreme wave event in the South China Sea region. Geoscience Letters, 4(1). more


Recent 230Th dating of fossil corals in west Luzon has provided new insights on the emergence of late Quaternary marine terraces that fringe west Luzon Island facing the Manila Trench. Apart from regional sea level changes, accumulated uplift from aseismic and seismic processes may have influenced the emergence of sea level indicators such as coral terraces and notches. Varied elevations of middle-to-late Holocene coral terraces along the west Luzon coasts reveal the differential uplift that is probably associated with the movement of local onland faults or upper-plate structures across the Manila Trench forearc basin. In Badoc Island, offshore west of Luzon mainland, we found notably young fossil corals, dated at 945.1 ± 4.6 years BP and 903.1 ± 3.9 years BP, on top of a ~5-m-high reef platform. To constrain the mechanism of emergence or emplacement of these fossil corals, we use field geomorphic data and wave inundation models to constrain an extreme wave event that affected west Luzon about 1000 years ago. Our preliminary tectonic and tsunami models show that a megathrust rupture will likely lead to subsidence of a large part of the west Luzon coast, while permanent coastal uplift is attributed to an offshore upper-plate rupture in the northern Manila Trench forearc region. The modeled source fault ruptures and tsunami lead to a maximum wave height of more than 3 m and inundation distance as far as 2 km along the coasts of western and northern Luzon. While emplacement of coral boulders by an unusually strong typhoon is also likely, modeled storm surge heights along west Luzon do not exceed 2 m even with Typhoon Haiyan characteristics. Whether tsunami or unusually strong typhoon, the occurrence of a prehistoric extreme wave event in west Luzon remains an important issue in future studies of coastal hazards in the South China Sea region.


9. Suzuki, S., Peña, R. E., Tam, T. A. III, Yumul, G. P. Jr., Dimalanta, c. B., Usui, M., Ishida, K. (2017). Development of the Philippine mobile belt in Nirthern Luzon from Eocene to Pliocene. Journal of Asian Earth Sciences, 142, Pages 32-44.more


The origin of the Philippine Archipelago is characterized by the combination of the oceanic Philippine Mobile Belt (PMB) and the Palawan Continental Block (PCB). This paper is focused on the geologic evolution of the PMB in northern Luzon from Eocene to Pliocene. The study areas (northern Luzon) are situated in the central part of the PMB which is occupied by its typical components made up of a pre-Paleocene ophiolitic complex, Eocene successions, Eocene to Oligocene igneous complex and late Oligocene to Pliocene successions. Facies analysis of the middle Eocene and late Oligocene to early Pliocene successions was carried out to understand the depositional environment of their basins. Modal sandstone compositions, which reflect the basement geology of the source area, were analyzed. Major element geochemistry of sediments was considered to reconstruct the tectonic settings. The following brief history of the PMB is deduced. During the middle Eocene, the PMB was covered by mafic volcanic rocks and was a primitive island arc. In late Eocene to late Oligocene time, the intermediate igneous complex was added to the mafic PMB crust. By late Oligocene to early Miocene time, the PMB had evolved into a volcanic island arc setting. Contributions from alkalic rocks are detected from the rock fragments in the sandstones and chemical composition of the Zigzag Formation. During the middle Miocene to Pliocene, the tectonic setting of the PMB remained as a mafic volcanic island arc.

10. Wu, J.-H., Li, Xi, X.-S., Kong, H., Wu, Q.-H., Peng, N.-L., Wu, X.-M., Cao, J.-Y., Gabo-Ratio, J.A.S. (2017). Geochemistry and geochronology of the mafic dikes in the Taipusi area, northern margin of North China Craton: Implications for Silurian tectonic evolution of the Central Asian Orogen. Journal of Earth System Science, 126(5), Page 64.more


The Taipusi area in the Bainaimiao Arc Belt is located in the northern margin of the North China Craton, at the southern margin of the middle Central Asian Orogenic Belt. It is characterized by large exposures of mafic dikes. In this contribution, we present first-hand whole-rock major and trace elements, zircon U–Pb geochronology and in situ trace element geochemistry data for these mafic rocks, which reveal their petrogenesis and tectonic evolution. These mafic dikes display varied compositions of SiO2SiO2 (49.42–54.29%), TiO2TiO2 (0.63–1.08%), Al2O3Al2O3 (13.94–17.60%), MgO (4.66–10.51%), Fe2O3Fe2O3 (1.59–3.07%), FeO (4.60–6.90%), CaO (4.57–8.91%), Na2ONa2O (1.61–4.26%), K2OK2O (0.92–2.54%) and P2O5P2O5 (0.11–0.29%). They are mainly of high-K calc-alkaline series with indistinct Eu anomalies, enriched in large ion lithophile elements (e.g., Rb, Ba, K and Sr) but depleted in high field strength elements (e.g., Nb, P and Ti). These suggest that the crystallizing magma was derived from enriched mantle altered by metasomatic fluids in a subduction setting with imprints of active continental margin features. The high concentrations of Hf, U, Th, Pb and Y, pronounced positive Ce but slightly negative Eu anomalies in zircons indicating that the magma underwent a fractional crystallization and crustal contamination process, with medium to high fO2fO2. Zircon LA–ICP–MS U–Pb dating yielded concordant ages of 437–442 Ma for these mafic dikes, which is consistent with the early Paleozoic volcanic arc magmatic activity in the Bainaimiao area. Hence, we conclude that the Bainaimiao Arc Belt is a continental arc formed by the southward subduction of the Paleo-Asian ocean during early Paleozoic.

11. Yasuhara, M., Iwatani, H., Hunt, G., Okahashi, H., Kase, T., Hayashi, H., … Renema, W. (2017). Cenozoic dynamics of shallow-marine biodiversity in the Western Pacific. Journal of Biogeography, 44(3), Pages 567–578. more


Aim: Cenozoic dynamics of large-scale species diversity patterns remain poorly understood, especially for the Western Pacific, in part, because of the paucity of well-dated fossil records from the tropics. This article aims to reveal the spatiotemporal dynamics of species diversity in the Western Pacific through the Cenozoic, focusing on the tropical Indo-Australian Archipelago (IAA) biodiversity hotspot. Location: Tropical and north-western Pacific Ocean. Methods: We analysed well-preserved fossil ostracodes from the tropical Western Pacific and combined their diversity data with other published data from the region to reconstruct Cenozoic dynamics of species diversity in the tropical and north-western Pacific Ocean. We fitted generalized additive models to test for differences in richness over time and across geographical regions while accounting for sample-size variation among samples. Results: Low-, mid- and high-latitude regions all show a similar diversity trajectory: diversity is low in the Eocene and Oligocene, increases from the Early Miocene to the Plio-Pleistocene but then declines to the present day. Present-day high biodiversity in these regions was established during the Pliocene with a remarkable diversity increase at that time. Latitudinal diversity patterns are relatively flat and never show a simple decline from the tropics to higher latitudes. Main conclusions: Western Pacific Cenozoic ostracodes exhibit a spatiotemporal pattern of species diversity that is inconsistent with the commonly reported and persistent pattern of declining diversity from the tropics to the extratropics. While this inconsistency could be interpreted as evidence that ostracodes are a contrarian clade, Atlantic ostracodes display a standard latitudinal species diversity gradient. Contrasting patterns between oceans suggest an important role for regional factors (e.g. plate tectonics and temporal geomorphological dynamics) in shaping the biodiversity of the Western Pacific.


12. Zuluaga, M. C., Norini, G., Lima, A., Albanese, S., David, C. P., & De Vivo, B. (2017). Stream sediment geochemical mapping of the Mount Pinatubo-Dizon Mine area, the Philippines: Implications for mineral exploration and environmental risk. Journal of Geochemical Exploration, 175, Pages 18–35. more


Stream sediments transport elements that are mobilized from adjacent slopes, representing the composition of the upstream watersheds. Thus, the analysis of the stream sediments allows depicting the spatial distribution of geochemical anomalies at the watershed level. In this study, 39 samples of stream sediments were collected in the Zambales Province, in the Philippines, characterized by the presence of the Mount Pinatubo volcano, the abandoned Cu Dizon Mine, small-mining of black sand, agriculture of rice, animal breeding, and fishing. Each sample was digested in aqua regia and was analyzed by ICP-MS to detect the content of 53 elements. This study is focused on elements with an environmental impact or associated to mineralization/ore occurring in the area. Background values for these elements have been evaluated by cumulative frequency curve to identify the occurrence of geochemical anomalies of geogenic or anthropogenic origin, mainly associated to the mining activity. Factor analysis, performed on normalized data with Additive Log Ratio transformation (ALR), allowed identifying three geochemical data associations, and a Geographic Information System (GIS) has been used to define the spatial distribution of the anomalies at the watersheds level. The GIS procedure assigns the value of the element concentration in the sampling location to the upstream watershed by hydrologic analysis of a Digital Elevation Model (DEM) of the study area. The main result of this study is a new type of geochemical mapping of the of the Mount Pinatubo-Dizon Mine area, representing a first approach to the definition of the environmental risk and the assessment of potential mineral resources.


1. Bascos, N.A.D., Mayer, M.P., Bukau, B., and Landry, S.J. (2017). The Hsp40 J-domain modulates Hsp70 conformation and ATPase activity with a semi-elliptical spring. Protein Science, DOI: 10.1002/pro.3223. more


Regulatory protein interactions are commonly attributed to lock-and-key associations that bring interacting domains together. However, studies in some systems suggest that regulation is not achieved by binding interactions alone. We report our investigations on specific physical characteristics required of the Hsp40 J-domain to stimulate ATP hydrolysis in the Hsp40-Hsp70 molecular chaperone machine. Biophysical analysis using isothermal titration calorimetry, and nuclear magnetic resonance spectroscopy reveals the importance of helix rigidity for the maintenance of Hsp40 function. Our results suggest that the functional J-domain acts like a semi-elliptical spring, wherein the resistance to bending upon binding to the Hsp70 ATPase modulates the ATPase domain conformational change and promotes ATP hydrolysis.

2. Cruz, M.C. and Hedreyda, C.T. (2017). Detection of plasmid-borne β-Lactamase genes in extended-spectrum β-Lactamase (ESBL) and non-ESBL-producing Escherichia coli clinical isolates. Philippine Journal of Science, 146 (2), Pages 167-175. more


Increasing frequency of infections caused by antibiotic resistant Escherichia coli strains producing extended-spectrum β-lactamase (ESBL) needs to be addressed by continuous surveillance and accurate detection of specific ESBLs genes for more effective treatment. A total of 71 β-lactam drug resistant isolates (26 phenotypically ESBL-producing and 45 non-ESBL-producing) were observed to carry approximately 23 kb plasmids. These isolates were subjected to β-lactamase gene-targeted PCR to detect plasmid-encoded blaTEM, blaSHV, blaCTX-M group1 and blaCTX-M group9 genes. BLAST analysis of amplicons revealed that plasmid-encoded blaTEM is most prevalent in both ESBL and non-ESBL-producing E. coli isolates. Plasmid-encoded blaSHV gene was only detected in 8 non-ESBL-producing isolates and explanation of such observation awaits additional studies to detect the possibility that the gene could be in the chromosomal DNA or to test the prevalence of the plasmid-encoded gene with more isolates. Twelve isolates of the ESBL-type blaCTX-M were identified from phenotypically identified ESBLs, comparable with 13 isolates detected with blaTEM. This observation suggests that the relatively newly emerging ESBL-type CTX-M is continuously increasing as one of the new β-lactamase derivatives among ESBL-producing E. coli in the clinical setting. This study reveals that there is discrepancy between the results of the phenotypic observation and genotypic analysis showing that the presence of ESBL-associated β-lactamase genes may be undetected when using the conventional phenotypic approach. Mutation in these unexpressed genes may result to ESBL antibiotic resistance, suggesting that the unexpressed and undetected genes may serve as reservoir for ESBL genes.

3. de la Peña, L. D., Cabillon, N. A. R., Amar, E. C., Catedral, D. D., Usero, R. C., Faisan, J. P., … Saloma, C. P. (2017). Mortality of Pond-cultured Litopenaeus vannamei Associated with Acute Hepatopancreatic Necrosis Disease (AHPND) and White Spot Syndrome Virus (WSSV) Infection in the Philippines. Fish Pathology, 52(1), Pages 38–41.more


Mortalities of up to 60% were observed in pond-culturedLitopenaeusvannamei in Bohol, Philippines. Histopathological examination revealed typical acute hepatopancreatic necrosis disease (AHPND) pathology. PCR test generated 1,269 bp and 230 bp amplicons confirmative for the toxin-producing AHPND strain ofVibrioparahaemolyticus among shrimp sampled from eight ponds. The same samples were subjected to PCR analyses for the presence of other viruses, namely WSSV, IHHNV, IMNV, and TSV. The samples were negative for the viruses except WSSV, which was detected after one-step PCR in six out of eight ponds. These results suggested that shrimp were infected dually with AHPNDV.parahaemolyticus and WSSV.

4. Dumilag, R.V. and Monotilla, W.D. (2017). Molecular diversity and biogeography of Philippine foliose Bangiales (Rhodophyta). Journal of Applied Phycology, Pages 1–14.more


Species circumscription based on phenotypes has frequently masked the actual species diversity in foliose Bangiales. Application of DNA sequence differences in this group has removed dependence on the utility of morphological characters traditionally considered for species discrimination. This study currently represents an extensive analysis of phylogeny and species discrimination of foliose Bangiales across most of their distributional range in the northern Philippines, particularly in Luzon Strait. Molecular assessment based on plastid rbcL and two mitochondrial loci, COI-5P, and cox2–3 spacer, suggested four major groups diagnostic of species lineage. As supported by the results from the four molecular species delimitation methods: PTP, bPTP, ABGD, and SPN, the confirmed Philippine foliose Bangiales species included Pyropia acanthophora, Py. tanegashimensis, and two cryptic taxa from Batanes Islands. The number of species detected in this study suggested that the true species composition of Philippine foliose Bangiales might be considerably lower than what was previously thought. It is possible however that a greater sampling effort in complete seasonal range of collections will reveal more species and extent of their actual distributions. Although the influence of northeast monsoon significantly affects the growth of foliose Bangiales in the Philippines, its role in shaping their present-day distribution remains unclear. Our molecular datasets however suggested that their current biogeographic distribution might reflect past vicariant events and is therefore more complex than have been previously regarded.

5. Zumaraga, M. P., Medina, P. J., Recto, J. M., Abrahan, L., Azurin, E., Tanchoco, C. C., … Palmes-Saloma, C. (2017). Targeted next generation sequencing of the entire vitamin D receptor gene reveals polymorphisms correlated with vitamin D deficiency among older Filipino women with and without fragility fracture. The Journal of Nutritional Biochemistry, 41, Pages 98–108.more


This study aimed to discover genetic variants in the entire 101 kB vitamin D receptor (VDR) gene for vitamin D deficiency in a group of postmenopausal Filipino women using targeted next generation sequencing (TNGS) approach in a case–control study design. A total of 50 women with and without osteoporotic fracture seen at the Philippine Orthopedic Center were included. Blood samples were collected for determination of serum vitamin D, calcium, phosphorus, glucose, blood urea nitrogen, creatinine, aspartate aminotransferase, alanine aminotransferase and as primary source for targeted VDR gene sequencing using the Ion Torrent Personal Genome Machine. The variant calling was based on the GATK best practice workflow and annotated using Annovar tool. A total of 1496 unique variants in the whole 101-kb VDR gene were identified. Novel sequence variations not registered in the dbSNP database were found among cases and controls at a rate of 23.1% and 16.6% of total discovered variants, respectively. One disease-associated enhancer showed statistically significant association to low serum 25-hydroxy vitamin D levels (Pearson chi-square P-value=0.009). The transcription factor binding site prediction program PROMO predicted the disruption of three transcription factor binding sites in this enhancer region. These findings show the power of TNGS in identifying sequence variations in a very large gene and the surprising results obtained in this study greatly expand the catalog of known VDR sequence variants that may represent an important clue in the emergence of vitamin D deficiency. Such information will also provide the additional guidance necessary toward a personalized nutritional advice to reach sufficient vitamin D status.


1. Aguilar, R., & Hermosa, N. (2017). Quadrant detector sensitivity and linearity index measurement with Laguerre-Gaussian beams. In Proceedings of SPIE - The International Society for Optical Engineeringmore


Quadrant detectors (QD) are mainly used in research and industries for displacement measurement purposes due to their high sensitivity and accuracy as compared to other photodiode devices. Their scope extend to sub-nanometer scales and they are also operable at a wide temperature range with fast response frequencies, which make them the best candidate for beam displacement measurements. A growing interest in the field of optics are beams carrying orbital angular momentum (OAM), particularly Laguerre-Gaussian (LG) beams, due to their remarkable applications, which include optical tracking and gravitational wave detection. This study shows the combined effect of using different OAM modes of LG beam and varying angles of inclination of the QD on the sensitivity response and linearity index of the QD. In general, it was observed that a lower OAM value for the LG beam gives a higher sensitivity for the QD and a higher angle of inclination for the QD leads to a higher linearity index. This result gives a larger range of application for the QD.

2.Agulto, V.C., Agulo, I.J., Sarmago, R.V. (2017). FTIR and UV-visible absorbance studies of hydrothermally grown ZnO coated with polyvinylpyrrolidone. Materials Science Forum, 895, Pages 73-78.more


Hydrothermally grown hexagonal wurtzite ZnO microrods coated with polyvinylpyrrolidone (PVP) via an ex-situ method, was successfully synthesized without using complex procedure or experimental setup. FTIR results confirm the presence of different functional groups of PVP at the ZnO surface and the chemical interaction of ZnO with the C=O ligand of the PVP molecule. The presence of PVP molecules prevents the absorption of atmospheric CO2 by the Zn2+ ions since PVP chemically interacts with ZnO by attaching to the exposed cations. The coating concentration doesn’t induce a frequency shift in the vibrations of the PVP functional groups. The ZnO microrods possess good optical quality as indicated by the high UV absorption and pronounced excitonic peak at room temperature, even after coating with higher PVP concentrations. 

3. Batac, R.C., Paguirigan, A.A., Tarun, A.B.,  Longjas, A.G. (2017). Sandpile-based model for capturing magnitude distributions and spatiotemporal clustering and separation in regional earthquakes. Nonlinear Processes in Geophysics, 24(2), Pages 179-187.more


We propose a cellular automata model for earthquake occurrences patterned after the sandpile model of self-organized criticality (SOC). By incorporating a single parameter describing the probability to target the most susceptible site, the model successfully reproduces the statistical signatures of seismicity. The energy distributions closely follow power-law probability density functions (PDFs) with a scaling exponent of around-1. 6, consistent with the expectations of the Gutenberg-Richter (GR) law, for a wide range of the targeted triggering probability values. Additionally, for targeted triggering probabilities within the range 0.004-0.007, we observe spatiotemporal distributions that show bimodal behavior, which is not observed previously for the original sand pile. For this critical range of values for the probability, model statistics show remarkable comparison with long-period empirical data from earthquakes from different seismogenic regions. The proposed model has key advantages, the foremost of which is the fact that it simultaneously captures the energy, space, and time statistics of earthquakes by just introducing a single parameter, while introducing minimal parameters in the simple rules of the sand pile. We believe that the critical targeting probability parameterizes the memory that is inherently present in earthquake-generating regions. 

4. Bernardo, R.C.S., Esguerra, J.P.H. (2017). Euclidean path integral formalism in deformed space with minimum measurable length. Journal of Mathematical Physics, 58(4).more


We study time-evolution at the quantum level by developing the Euclidean path integral approach for the general case where there exists a minimum measurable length. We derive an expression for the momentum-space propagator which turns out to be consistent with recently developed canonical transformation. We also construct the propagator for maximal localization which corresponds to the amplitude that a state which is maximally localized at location ↑0 propagates to a state which is maximally localized at location ↑00 in a given time. Our expression for the momentum space propagator and the propagator for maximal localization is valid for any form of time-independent Hamiltonian. The nonrelativistic free particle, particle in a linear potential, and the harmonic oscillator are discussed as examples.

5. Caballar, R., Butanas, B., Villegas, B., & Estrella, M. (2017). Dissipation induced quantum transport on a finite one-dimensional lattice.


6. Cabello, N. I., Tingzon, P., Cervantes, K., Cafe, A., Lopez, J., Mabilangan, A., … Estacio, E. (2017). Luminescence and carrier dynamics in nanostructured silicon. Journal of Luminescence, 186, Pages 312–317. 


7. Cafe, A.I., Lopez, J., Lopez, L., Jr., Faustino, M.A.,  Mabilangan, A.,  Salvador, A., Somintac, A. (2017). Porous silicon optical template for determination of chromatic dispersion of transparent liquid mixture. AIP Conference Proceedings, 1808(1). doi:


Porous silicon was fabricated through electrochemical etching and is used as an optical template for liquid sensing application. Using reflectance spectroscopy, change in optical properties such as refractive index and reflectivity upon liquid introduction were obtained. Chromatic dispersion of porous silicon upon detection of transparent liquids such as absolute ethanol, methanol, 2-propanol and distilled water were determined for spectral range 450nm to 1100nm. Mixture of the organic transparent liquid and water was also tested. In this study, porosity and liquid's concentration were varied to establish the sensitivity of detection. Expected ideal values were also simulated for comparison and correction factor computation. Results provide calibration basis for water quality assessment, environmental monitoring, and diagnostic application. 

8. Calaque, P.M., Vergara, C.J., Ballesteros, L.I., Somintac, A. (2017). Development and characterization of a novel ZnO nanorods-SnO2:F nanoflakes thin film for room-temperature ammonia and humidity sensing (Conference Paper). AIP Conference Proceedings, 1808.more


A unique and novel thin film of fluorine-doped tin oxide (SnO2:F) nanoflakes on ZnO nanorods were fabricated using nebulized spray pyrolysis technique (NSPT) and hydrothermal growth method, respectively, for ammonia and humidity sensing applications. XRD studies confirm the growth of a hexagonal wurtzite ZnO and a tetragonal SnO2:F. SEM images of the film fabricated for preliminary studies evidently revealed ZnO nanorods and SnO2:F nanoflakes. The response of the fabricated ZnO-SnO2:F nanostructure thin film sensor on varying concentrations of water vapor and ammonia at room temperature were investigated. Results have shown that it had higher sensor response to ammonia than to water vapor. Moreover, it was observed to have a higher sensor response on ammonia and humidity compared to the fabricated sensor of SnO2:F thin film alone. The films could detect humidity and ammonia even at a low level of 9 ppm and 5 ppm, respectively, showing its potential use for various fields such as environmental monitoring and chemical industries. 

9. Cruz, P. C. S., Bernardo, R. C. S., & Esguerra, J. P. H. (2017). Energy levels of a quantum particle on a cylindrical surface with non-circular cross-section in electric and magnetic fields. Annals of Physics, 379, Pages 159–174.


10. de los Reyes, A., Prieto, E. A. P., Omambac, K., Porquez, J., Lopez, L., Gonzales, K. C., … Salvador, A. A. (2017). Terahertz emission characteristics of GaMnAs dilute magnetic semiconductor under 650 mT external magnetic field. Current Applied Physics, 17(4), Pages 522–526.more


We investigate the effects of an externally applied magnetic field on the terahertz (THz) emission of Gallium Manganese Arsenide (GaMnAs) films grown via molecular beam epitaxy (MBE). Results show that low Mn-doping in GaMnAs resulted to increased THz emission as compared with a SI-GaAs substrate. Further increase in Mn-doping content resulted to a comparably less THz emission, which is attributed to reduced crystallinity and higher free-carrier absorption. Under an external magnetic field, the contributions of the Bup and Bdown-related THz emission were observed to be asymmetric: possibly due to intrinsic magnetic properties of GaMnAs. 

11. Empizo, M.J.F., Santos-Putungan, A.B., Yamanoi, K., Salazar, H.T., Jr., Anguluan, E.P., Mori, K., Arita, R., Minami, Y., Luong, M.V., Shimizu, T., Estacio, E.S., Somintac, A.S., Salvador, A.A., Sarmago, R.V., Fukuda, T., Sarukura, N. (2017). Structural and optical characterization and scintillator application of hydrothermal-grown ZnO microrods. Optical Materials, 65, Pages 82-87.more


ZnO microrods are fabricated by a simple hydrothermal growth route using zinc acetate dihydrate [Zn(CH3COO)2·2H2O] and hexamethylenetetramine [(CH2)6N4] aqueous solutions. The as-prepared microrods exhibit uniform dimensions, well-faceted surfaces, and hexagonal crystal structure. The microrods also have an intense ultraviolet (UV) emission at 392 nm with an average lifetime of 80 ps. No peaks are observed at the visible wavelengths that can be attributed to defect-related emissions. With excellent structural and optical properties and with loose adhesion to their substrates, the ZnO microrods can be isolated, harvested, and manipulated and can be integrated as building blocks of a microstructured scintillator screen. The proposed scintillator screen possibly offers efficient and precise detection with high resolution. Hydrothermal-grown ZnO microrods then hold a promise towards radiation detector innovation and integrated optoelectronic microsystems. 

12. Empizo, M.J.F., Yamanoi, K., Mori, K., Iwano, K., Iwasa, Y., Minami, Y., Arita, R., Fukuda, K., Takano, K., Shimizu, T., Nakajima, M., Yoshimura, M., Sarukura, N., Norimatsu, T., Hangyo, M., Azechi, H., Fukuda, T., Singidas, B.G., Sarmago, R.V., Oya, M.d, Ueda, Y. (2017). Optical damage assessment and recovery investigation of hydrogen-ion and deuterium-ion plasma-irradiated bulk ZnO single crystals. Journal of Applied Physics, 121(17), Article number 175102.more


In realizing zinc oxide (ZnO) scintillator applications, we assess the optical damage and investigate the recovery of hydrogen-ion (H-ion) and deuterium-ion (D-ion) plasma-irradiated bulk ZnO single crystals. Hydrothermal-grown bulk crystals are irradiated with H-ion and D-ion beams with 1 keV energy and 10 20 m − 2 s − 1 flux. After irradiation, the single crystals exhibit decreased visible transparencies, redshifted ultraviolet (UV) emission peaks, shortened UV emission lifetimes, and suppressed visible emission bands. These changes in the optical transmittances and photoluminescence emissions are attributed to the generation of defects during irradiation and to the interaction of hydrogen with other defects and/or impurities. Although modified by ion irradiation, the optical properties of the ZnO crystals, except for the UV emission lifetimes, recover hours after without any sample treatment and only at room temperature. Compared with the H-ion-irradiated sample, the D-ion-irradiated crystal has a slower recovery which may be related to the ions' masses, energy losses, and absolute diffusivities. Our results nevertheless show that bulk ZnO single crystals exhibit resistance to and recovery from H-ion and D-ion irradiation and can therefore be used as scintillator materials for radiation detectors inside future fusion reactors.

13. Felix, M. J., Muldera, J., Somintac, A., Salvador, A., & Estacio, E. (2017). Enhanced Terahertz emission and raman signal from silicon nanopyramids. Science of Advanced Materials, 9(2), Pages 214–219. 


14. Galapon, E. A. (2017). The problem of missing terms in term by term integration involving divergent integrals. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 473(2197).more


Term by term integration may lead to divergent integrals, and naive evaluation of them by means of, say, analytic continuation or by regularization or by the finite part integral may lead to missing terms. Here, under certain analyticity conditions, the problem of missing terms for the incomplete Stieltjes transform, ∫ a0 f (x)(ω + x)-1 dx, and the Stieltjes transform itself, ∫ 0 f (x)(ω + x)-1 dx, is resolved by lifting the integration in the complex plane. It is shown that the missing terms arise from the singularities of the complex-valued function f (z)(ω + z)-1, with the divergent integrals arising from term by term integration interpreted as finite part integrals. 

15. Galapon, E. A. (2017). Erratum: “The Cauchy principal value and the Hadamard finite part integral as values of absolutely convergent integrals.Journal of Mathematical Physics, 58(19901–1), 2016–2017. 


16. Husay, H.A., Balgos, M.H., Tumanguil, M.A., Estacio, E., Salvador, A., Somintac, A. (2017). Terahertz emission from CuO nanowires synthesized through thermal oxidation of Cu foils. Science of Advanced Materials, 9(2), Pages 193-198.


We demonstrate terahertz (THz) emission from cupric oxide nanowires (CuO NWs) synthesized through thermal oxidation of Cu foils in ambient air by heating the foils in a hotplate for two hours at 300, 350, 400, and 450 °C. Scanning electron microscopy revealed the changes in the morphology of the foils; from the formation of a film composed of grains at 300 and 350 °C to the formation of NWs at 400 and 450 °C. The NWs were seen to have densities and dimensions that vary depending on the oxidation temperature. X-ray diffractometry showed that the grains that form at 300 and 350 °C were composed of a mixed phase of Cu2O and CuO, while the CuO NWs were observed to crystallize at temperatures greater than 400 °C. THz time domain spectroscopy (THz-TDS) showed that the foils containing CuO NWs were observed to emit THz radiation. It was further shown that increasing the density and dimensions of the NWs enhances the transient photocurrent generated throughout the length of the NWs, resulting in a stronger THz emission. 

17. Jaculbia, R.B., Afalla, J.P., Balgos, M.H., Omambac, K., Lumantas, D.A.Email Author, Salvador, A., Estacio, E., Somintac, A. (2017). Tunneling at room temperature in GaAs/AlGaAs asymmetric coupled double quantum wells observed via time resolved photoluminescence spectroscopy. Superlattices and Microstructures. 109, Pages 324-329.more


We have demonstrated experimental evidence of non-resonant tunneling at room temperature in GaAs/AlGaAs asymmetric coupled double quantum wells (ACDQW's) using time-resolved photoluminescence (TRPL) spectroscopy at 300 K. Two ACDQW samples (A and B) with a barrier thickness of 25 Å were grown via molecular beam epitaxy. The energy separation (δE) between the ground state of the conduction band of the wide well and that of the narrow well are 42.7 meV and 19.5 meV, for samples A and B respectively. The TRPL measurement revealed a double decay rate in sample A whose δE is greater than one GaAs longitudinal optical phonon energy (36 meV), suggesting a phonon assisted tunneling mechanism. The evidence of tunneling was supported by measuring the relative intensity of the PL contributions from the narrow and wide well at 10 K. 

18. Narag, J., Hermosa, N. (2017). Response of quadrant detectors to structured beams via convolution integrals. Journal of the Optical Society of America A: Optics and Image Science, and Vision, 34(7), Pages 1212-1216.more


We propose a new expression for the response of a quadrant detector using convolution integrals. This expression, exploiting the properties of the convolution, is easier to evaluate by hand. Computationally, it is also practicable to use since a large number of computer programs can evaluate convolutions right away. We use the new expression to obtain an analytical form of the response of a quadrant detector for a Gaussian beam and for Hermite-Gaussian beams in general. We compare this analytic expression for the response for the Gaussian beam with the approximations from previous studies and with the response obtained through simulations. From the response, we also obtained an analytical form for the sensitivity of the quadrant detector to a Gaussian beam. Lastly, we demonstrate the computational ease of using our new expression for the response by calculating the sensitivity of the quadrant detector to the Bessel beam.


19. Paguirigan, A.A., Jr., Angco, M.J.G., Bantang, J.Y. (2017). A fragmentation model of earthquake-like behavior in internet access activity. International Journal of Modern Physics C, 28(7), Article number 1750092.more


We present a fragmentation model that generates almost any inverse power-law size distribution, including dual-scaled versions, consistent with the underlying dynamics of systems with earthquake-like behavior. We apply the model to explain the dual-scaled power-law statistics observed in an Internet access dataset that covers more than 32 million requests. The non-Poissonian statistics of the requested data sizes m and the amount of time τ needed for complete processing are consistent with the Gutenberg-Richter-law. Inter-event times δt between subsequent requests are also shown to exhibit power-law distributions consistent with the generalized Omori law. Thus, the dataset is similar to the earthquake data except that two power-law regimes are observed. Using the proposed model, we are able to identify underlying dynamics responsible in generating the observed dual power-law distributions. The model is universal enough for its applicability to any physical and human dynamics that is limited by finite resources such as space, energy, time or opportunity. 

20. Pang, J. C. S., & Monterola, C. P. (2017). Dendritic growth model of multilevel marketing. Communications in Nonlinear Science and Numerical Simulation, 43, Pages 100–110.more


Biologically inspired dendritic network growth is utilized to model the evolving connections of a multilevel marketing (MLM) enterprise. Starting from agents at random spatial locations, a network is formed by minimizing a distance cost function controlled by a parameter, termed the balancing factor bf, that weighs the wiring and the path length costs of connection. The paradigm is compared to an actual MLM membership data and is shown to be successful in statistically capturing the membership distribution, better than the previously reported agent based preferential attachment or analytic branching process models. Moreover, it recovers the known empirical statistics of previously studied MLM, specifically: (i) a membership distribution characterized by the existence of peak levels indicating limited growth, and (ii) an income distribution obeying the 80−20 Pareto principle. Extensive types of income distributions from uniform to Pareto to a “winner-take-all” kind are also modeled by varying bf. Finally, the robustness of our dendritic growth paradigm to random agent removals is explored and its implications to MLM income distributions are discussed. 

21. Rosario, L.M.D.ab, Lee, H.V., Jr.a, Penafiel, E.a, Ramos, H.J.c, Bo-Ot, L.M.T.d,  Fischer, R.V.e, Tumlos, R.B. (2017). Characterization of a Microwave-Induced Atmospheric-Pressure Ar-N2 Plasma Pencil. IEEE Transactions on Plasma Science, 45(2), Pages 301-309.more


A microwave-induced atmospheric-pressure plasma pencil was developed with an Ar-N2 gas mixture supplied to a coaxial transmission line. High-frequency simulation showed sufficient high electric field at the tip of the inner conductor, which resulted to automatic plasma ignition and a stable operation. The dependence of the characteristics of the plasma pencil from Ar and N2 gas flow rates was extensively studied. At moderate Ar gas flow rates, the plasma pencil can be operated at several tens of watts to achieve a near room-temperature and centimeter-long Ar-N2 plasma plume with OH and NO radicals as active species. Optical emission spectroscopy was also used to determine the vibrational and rotational temperatures of the plasma pencil. The vibrational temperature of N2 from the second positive system (2PS) can be obtained at moderate gas flow rates, since there was a good linear fitting with the Boltzmann distribution. At these gas flow rates, the vibrational and rotational temperatures of N2 from 2PS were found to be 0.42 and 0.29 eV, respectively. 

22. Rosete, M. M., Zosa, M. H., & Sarmago, R. V. (2017). Effect of Potassium Chloride as a Supporting Electrolyte on the Dispersion Towards the Fabrication of Films by Electrophoretic Deposition of Bi2Sr2CaCu2 O 8 in Ethanol. Journal of Superconductivity and Novel Magnetism, Pages 3–8.more


Bi2Sr2CaCu2O8 (Bi-2212) powder was fabricated using solid state reaction method. The suspensions were prepared containing finely ground Bi-2212 powder with and without potassium chloride (KCl) addition. Settling experiments and measurements of zeta potential, particle size distribution, and electrophoretic mobility were performed to determine the optimal concentration of the supporting electrolyte. Bi-2212 suspensions were used in electrophoretic deposition (EPD), and the films were heat treated. The results showed that the optimal concentration of KCl is 5.21 wt %. The zeta potential at this concentration is highest at about 31.10 mV, the settling velocity is lowest 3.84 mm/min, and the particle size is smallest (450 nm), which indicate that the dispersion is better due to the reduction of intermolecular attraction. The effects of KCl as a flux were observed in the microstructure and superconducting properties of Bi-2212 film. The smoothest surface morphology, high c-axis orientation, and highest critical temperature (Tc)-onset of 84.73 K were obtained from the film prepared with optimized Bi-2212 suspension. 

23. Tinacba, E. J. C., Nuñez, J. A., Tumlos, R. B., & Ramos, H. J. (2017). ZnO/Zn and ZnO film deposited via microwave atmospheric plasma jet as photo-catalyst for Rhodamine 6G dye degradation. Thin Solid Films, 624, Pages 197–200. 


24. Tingzon, P., Lopez, L., Oliver, N., Cabello, N., Cafe, A., De Los Reyes, A., … Somintac, A. (2017). Terahertz emission and photoluminescence of Silicon Nanowires electrolessly etched on the surface of Silicon (100), (110), and (111) substrates for photovoltaic cell applications. Photonics and Nanostructures - Fundamentals and Applications, 24, Pages 1–6.more


Silicon nanowires (SiNWs) were etched on Si (100), (110), and (111) substrates. Slanted nanowires with respect to the surface normal were produced on the Si (110) and (111) substrates, and vertical nanowires were produced on the Si (100) substrate. Photoluminescence spectroscopy exhibited luminescence lines attributed to oxide defects from the nanowires. A comparison of the transient photocurrent as measured using terahertz time-domain spectroscopy revealed an increase in the THz emission from the SiNWs on Si (110) substrate compared to those grown on (100) substrate. Reorienting the dipole moment by applying an external 650 mT magnetic field suggested that the carrier transport was confined along the axis of the nanowires. Understanding the photocarrier and transport recombination properties in SiNWs may prove useful in the design considerations for future SiNW photovoltaic cell applications. 

25. Villacorta, R. B., Faith Javier Roque, K., Tapang, G. A., & Jacinto, S. D. (2017). Plant extracts as natural photosensitizers in photodynamic therapy: in vitro activity against human mammary adenocarcinoma MCF-7 cells. Asian Pacific Journal of Tropical Biomedicine, 7(4), Pages 358–366. 


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1. Apaga, D. L. T., Dennis, S. E., Salvador, J. M., Gayvelline, C., & Ungria, M. C. A. De. (2017). Comparison of Two Massively Parallel Sequencing Platforms using 83 Single Nucleotide Polymorphisms for Human Identification. Scientific Reports, Pages 1–6. 


2. Atayde, E.C., J., Berenguel, M. M., & Arco, S. . (2017). RAFT polymerization of dual responsive hyperbranched-star copolymers of methacrylic acid and poly(Ethylene glycol). Materials Science Forum, 890, Pages 78–81. 


3.Buhian, W. P. C., Rubio, R. O., & Martin-Puzon, J. J. (2017). Chromatographic fingerprinting and free-radical scavenging activity of ethanol extracts of Muntingia calabura L. leaves and stems. Asian Pacific Journal of Tropical Biomedicine, 7(2), Pages 139–143. 


4. Calayag, A. M. B., Paclibare, P. A. P., Santos, P. D. M., Bautista, C. A. C., & Rivera, W. L. (2017). Molecular characterization and antimicrobial resistance of Salmonella enterica from swine slaughtered in two different types of Philippine abattoir. Food Microbiology, 65, Pages 51–56. 


5. Celeste, R. O., Corcino, R. B., & Gonzales, K. J. M. (2017). Two approaches to normal order coefficients. Journal of Integer Sequences, 20(3). 


6. de la Cruz, R. J., Merino, D. I., & Paras, A. T. (2017). Every 2 n -by-2 n complex matrix is a sum of three symplectic matrices. Linear Algebra and Its Applications, 517, Pages 199–206.


7. Loquias, M. J. C., Valdez, L. D., & Walo, M. L. B. (2017). Color groups of colorings of N-planar modules. In Journal of Physics: Conference Series (Vol. 809). 


8. Nuñez, J. A. P., Salapare, H. S., Villamayor, M. M. S., Siringan, M. A. T., & Ramos, H. J. (2017). Antibacterial efficiency of magnetron sputtered TiO 2 on poly(methyl methacrylate). Surfaces and Interfaces, 8, Pages 28–35. 


9. Pagalilauan, H. A. M., Paraoan, C. E. M., & Vital, P. G. (2017). Detection of pathogenic bioaerosols and occupational risk in a Philippine landfill site. Archives of Environmental & Occupational Health, Pages 1–8. 


10. Paraoan, C. E. M., Rivera, W. L., & Vital, P. G. (2017). Detection of Class I and II integrons for the assessment of antibiotic and multidrug resistance among Escherichia coli isolates from agricultural irrigation waters in Bulacan, Philippines. Journal of Environmental Science and Health, Part B, 1234(March), Pages 1–8. 


11. Tayaban, K. M. M., Pintor, K. L., & Vital, P. G. (2017). Detection of potential harmful algal bloom-causing microalgae from freshwater prawn farms in Central Luzon, Philippines, for bloom monitoring and prediction. Environment, Development and Sustainability, Pages 1–18.