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Faculty Publication (2018)

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1. Catap, E.S., Kho, M.J.L., Jimenez, M.R.R. (2018). In vivo nonspecific immunomodulatory and antispasmodic effects of common purslane (Portulaca oleracea Linn.) leaf extracts in ICR miceJournal of Ethnopharmacology, 215, Pages 191-198.  more

Abstract:

Ethnopharmacological relevance

Portulaca oleracea (common purslane) is used in traditional medicine to cure various illnesses. However, its immune-protective properties and antispasmodic effects still need more pharmacological data if the plant will be utilized in herbal and drug formulations. Therefore, the present study determined the capacity of this plant species to modulate nonspecific immune responses and to confirm its antispasmodic activity in vivo in ICR mice.

2. Dumilag, R.V., Monotilla, W.D. (2018). Molecular diversity and biogeography of Philippine foliose Bangiales (Rhodophyta)Journal of Applied Phycology, 30 (1), Pages 173-186.more

Abstract:

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.

3. Galidon, J.M., Pasion, B., Tongco, M.D., Fidelino, J., Duya, M.R., Ong, P.S. (2018). Plant diversity patterns in remnant forests and exotic tree species-based reforestation in active limestones quarries in the Luzon and Mindanao biogeographic sub-regions in the PhilippinesEcological Research, 33 (1), Pages 63-72.more

Abstract:

The Philippines is both a megadiversity country and a global biodiversity hotspot. The diversity patterns of three major plant groups were assessed: (1) trees (trees and palms), (2) herbs (grasses, shrubs, forbs, ferns), and (3) epiphytes (climbers and epiphytes), by determining the changes in compositional and species richness patterns in two forest conditions, i.e., remnant forests and exotic tree species-based reforested areas, in active forest over limestone quarries in the Luzon and Mindanao biogeographic sub-regions of the Philippines. We identified 458 species comprising 266 tree species, 95 herbaceous species and 97 epiphyte species. Of these, 21 species were categorized as threatened species. Species composition differed between remnant forests and exotic tree species-based reforested areas for tree species and epiphyte species, while composition differences between the Luzon and Mindanao biogeographic sub-regions were limited to tree species only. Differences in species diversity (in terms of richness) were observed between biogeographic sub-regions for all plant groups, while differences between forest conditions were found for tree and epiphyte species only. Interestingly, there were significantly fewer numbers of exotic species in bigger remnant forest sites and in older exotic tree species-based reforested sites, while larger numbers of native species occurred in older than in younger exotic tree species-based reforested sites. The results emphasize the importance of understanding forest recovery in disturbed ecosystems. Conservation attention should focus on protecting remaining forests and planting native species as part of a forest restoration strategy to enhance faster forest recovery and re-connecting remnant forest patches.

4. Eun-Shik Kim, Trisurat, T., Muraoka, H., Shibata, H., Amoroso, V., Boldgiv, B., Hoshizaki, K., Kassim, A.R., Young-Sun Kim, Hong Quan Nguyen, Ohte, N., Ong, P.S., Chiao-Ping Wang. (2018). The International Long-Term Ecological Research–East Asia–Pacific Regional Network (ILTER-EAP): history, development, and perspectivesEcological Research, 33 (1), Pages 19-34.more

Abstract:

There are growing needs to broaden and deepen our multi-faceted understanding of the ecosystems, and the networks of Long-Term Ecological Research (LTER) can play significant roles in fostering and applying ecosystem studies at regional and global scales. The International LTER Network (ILTER) is organized as a global network of field research sites and scientists to address current ecological issues such as biodiversity loss and ecosystem degradation within a globally changing environment. The ILTER East Asia–Pacific Regional Network (ILTER-EAP) is one of the four constituent ILTER regional networks. Since 1995, ILTER-EAP has been developed to promote data sharing, research collaborations and capability building in the science and to bridge gaps between societal needs and scientific imperatives on concerns in the Asia–Pacific Region. Currently, ILTER-EAP comprises nine formal ILTER members and two associate networks. Their activities involve long-term and multiple-site observations of structural, functional and developmental aspects of ecosystems, data sharing, and bridging society and ecological science. This paper presents a review of the activities of ILTER-EAP, focusing on its: (1) vision and the development following its inception, (2) scientific activities and major outputs related to selected thematic areas, (3) contributions from ILTER-EAP to the international initiatives, and (4) future challenges and opportunities relating to its development and role in facilitating regional and global research collaborations. Accordingly, regional research questions were identified that could be most effectively addressed by opening up a common research platform, integrated data management system and the network science, which is open to all interested parties.

5. Matias, A.M., Hereward, J. (2018). The complete mitochondrial genome of the five-lined cardinalfish Cheilodipterus quinquelineatus (Apogonidae). Mitochondrial DNA Part B, 3 (2), Pages 521-522. more

Abstract:

Cheilopdipterus quinquelineatus (Apogonidae) is an interesting species for investigating processes driving population divergence in marine system due to its wide distribution and life-history traits. However, to date, there is a limited genetic resource available for this species, or the family Apogonidae as exemplified by the availability of only two mitogenomes. In this study, we assembled the whole mitochondrial genome of this species yielding a 16,537 bp circular assembly composed of the typical vertebrate mitochondrial features. Phylogenetic inference of the supraordinal group of C. quiquelineatus showed monophyly of the major families. 

6. Pedales, R.D.C., Fontanilla, I.K.C. (2018). Forensic entomology in the Philippines: Establishing baseline data on the forensically important blow fly species Chrysomya megacephala (Fabricius, 1974)Philippine Journal of Science, 147 (1).

Abstract:

The Philippines is yet to adapt and implement guidelines and protocols in forensic entomology, particularly establishing local databases. Considering the efforts made by neighboring Southeast Asian countries in the field, the nation has been left behind in insect evidence-based investigations. Of utmost importance to forensic entomology are blow flies (Diptera: Calliphoridae), which are primary colonizers of carrion. Through knowledge of their distribution, identity, and growth rates, investigators are able to provide a post-mortem interval that is most accurate after the onset of putrefaction. The Philippines has a total of 83 blow fly species recorded, including the cosmopolitan species Chrysomya megacephala. This paper aims to establish a baseline reference in Philippine forensic entomology by mapping the distribution, providing DNA barcodes, and estimating larval growth rates from oviposition to pupariation of C. megacephala. Distribution data were mapped in QGIS using localities from fieldwork data in this study and those in the Key to the Philippine Calliphoridae by Kurahashi and Magpayo. DNA barcodes of specimens from Isabela, Quezon City, and Marinduque in the Philippines matched with C. megacephala from the database in GenBank and revealed a possible SNP in the fragment amplified. C. megacephala was reared from oviposition in a simple incubation set-up to estimate the duration of development to pupariation, which ranged 100-113 hours. This is the first study on the distribution, molecular identification, and development of C. megacephala in the Philippines. Further work is needed to distinguish among populations of the species and to construct more precise growth curves. 

7. Perez, C.M.T., Pajares, I.G., Alcantara, V.A., Simbahan, J.F. (2018). Bacterial laminarinase for application in ethanol production from brown algae Sargassum sp. using halotolerant yeastBiofuel Research Journal, 5 (1), Pages 792-797.more

Abstract:

Macroalgae are known to have many industrial applications, with current research targeting the potential of macroalgal biomass as feedstock in production of biofuels. Marine algal biomass is rich in storage carbohydrates, laminarin, and cellulose, which can be converted to fermentable sugars using appropriate enzymes, for fermentation to ethanol. This study focused on ethanol production from macroalgae using only enzymatic treatment for saccharification of algal biomass. This involved the isolation and identification of cellulase and laminarinase-producing microorganisms from mangrove area in the Philippines and production of partially purified enzymes for algal biomass saccharification. Results showed that the partially purified laminarinase produced from Bacillus sp. was capable of hydrolyzing the laminarin present in the macroalage. Fermentation of the algal hydrolysate yielded only small amount of ethanol due to lack of other pre-treatment methods, however, it was observed that higher ethanol was produced in saccharification treatments using a combination of cellulase and laminarinase which implies a possible synergistic effect between the two enzymes. 

8. Ramos, D.A.E., Batomalaque, G.A., Anticamara, J.A. (2018). Current status of Philippine Mollusk Museum Collections and Research, and their Implications on Biodiversity Science and ConservationPhilippine Journal of Science. 147 (1), Pages 123-163.

Abstract:

Mollusks are an invaluable resource in the Philippines, but recent reviews on the status of museum collections of mollusks or research trends in the country are lacking. Such assessments can contribute to a more comprehensive evaluation of natural history museums in the Philippines, as well as biodiversity management. This review showed that local museums in the Philippines have much to improve in terms of their accessibility and geographic coverage in order to effectively cater to research and conservation needs of the country. Online access to databases was lacking for local museums, making it cumbersome to retrieve collection information. The UST museum held the most species and subspecies across all museums (4899), comparable to the national museums of countries such as the USA and France. In terms of size, there were larger Philippine mollusk collections in museums abroad. Majority of mollusk specimens come from Regions 4 and 7, while the CAR and Region 12 were least sampled. Publications on Philippine mollusks are dominated by taxonomic and biodiversity research. Around 80% of publications were on marine species. Therefore, there is a great need to (1) improve access to collections by publishing databases and collections online; (2) improve spatial coverage of mollusk sampling to have a better nationwide (and habitat) representation of Philippine mollusk diversity; (3) fill important knowledge gaps in the ecological assessment of exploited mollusks and minor taxa that will be useful in status assessment and management; and (4) build a network of functional museums to facilitate mollusk and invertebrate researches and conservation by making properly curated specimens available to more researchers nationwide.

9. Rodriguez, J.P., Lee, Y.K., Woo, D.G., Shim, J.S., Geraldino, J.L., Jacinto, S.D., Lee, S. (2018). Flavonoids from Cirsium japonicum var. maackii pappus as inhibitors of aldose reductase and their simultaneous determinationChemical Papers, 72 (1), Pages 81-88.more

Abstract:

Aldose reductase is an enzyme in the polyol pathway which is associated in the progression of diabetic complications. In this study, we evaluated the inhibitory activity of Cirsium japonicumvar. maackii pappus (CJP) against rat lens aldose reductase (RLAR). The ethanolic extract, fractions and isolated flavonoids were subjected to an RLAR assay. Isolation of chloroform (CHCl3) and ethyl acetate (EtOAc) fractions led to the identification of four flavonoids: hispidulin (1), cirsimaritin (2), apigenin (3), and cirsimarin (4). The RLAR assay results suggested that the EtOAc fraction and flavonoids 1 and 3 promoted better AR inhibition than did TMG (control). The half-maximal inhibitory concentration (IC50) of compounds 1 and 3was 0.77 and 3.19 μM, respectively. A simultaneous determination of flavonoid content using HPLC–UV indicated that CJP contained large amounts of compounds 2 and 3 (1.65 and 1.84 mg/g, respectively). Flavonoids from Cirsium species have been widely reported to show various pharmacological activities. This study indicated that CJP has the potential to prevent diabetic complications and was a potential source of flavonoids.

10. Romana-Eguia, M.R.R., Santos, B.S., Ikeda, M., Basiao, Z.U., Kijima, A. (2018). Genetic assessment of milkfish (Chanos chanos Forsskal) stocks based on novel short tandem repeats for marker‐aided broodstock managementAquaculture Research, 49 (4), Pages 1557-1568.more

Abstract:

Milkfish hatchery broodstock are either from on‐grown wild‐caught or hatchery‐produced fry/juveniles. To determine if a marker‐assisted management scheme can be formulated for improved milkfish hatchery production, milkfish stocks were genetically characterized using nine novel short tandem repeats or microsatellites. Eight wild‐bred Philippine stocks (CLA, CUR, CAM, SIH, SBH‐I1, HH, PAL and ZH‐P0), four hatchery‐bred stocks (SBH‐I2, SBH‐D, BoH and ZH‐F1), two farm stocks of known mixed lineages (SPH and BDH) and one Indonesian hatchery‐bred stock (WJH) were assessed. WJH was included since milkfish fingerlings from Indonesia reared in Philippine farms could be developed into future broodstock. Mean allelic richness (Ar) was highest in wild‐bred stocks (9.5) and lowest in hatchery‐bred spawners (9.1). Mean expected heterozygosities (He) were relatively similar in all stocks with wild‐bred stocks slightly higher (0.67) than the others. An analysis of molecular variance indicated significant yet low genetic differentiation among stocks (FST = 0.013; p = .000) where variation (98.6%) was explained by intra‐stock differences. In some of the domesticated stocks, reductions in mean allelic richness were observed in first generation hatchery broodstock (e.g. ZH‐F1; Ar = 8.3), compared with their founder stock (e.g. ZH‐P0; Ar = 9.4). The Indonesian stock was similar to local wild‐bred stocks based on genetic variability indices; thus, it might be likely that the local stocks’ fitness traits could be comparable with the imported milkfish stock which has been perceived to be better. The quality of locally available farmed milkfish and prospects of formulating a broodstock management scheme for the production of good quality milkfish seedstock are herewith discussed.

11. Tamayo, N.C.A., Anticamara, J.A. , Acosta-Michlik, L. (2018). National estimates of values of Philippine Reefs' Ecosystem ServicesEcological Economics, 146, Pages 633-644.more

Abstract:

Ecosystem Services (ES) – the direct (e.g., food and natural medicines) and indirect (e.g., cultural diversity and aesthetic values) benefits people obtain from various ecosystems – need to be assessed to aid decision makers and concerned public in creating policies that ensure continuous flow of ES to their beneficiaries (e.g., fisheries, food, income, livelihood, and traditional way of life to fishers and consumers). However, to date, ES assessments in Philippine reefs are mostly concentrated only on fisheries and tourism or on few areas in the Philippines (e.g., Pangasinan and Bohol Marine Triangle). This study fills research gaps by assessing coral reefs across 15 regions in the Philippines by estimating the following: (1) potential reef fisheries and Willingness-To-Pay (WTP) biodiversity values using underwater surveys and literature data, (2) reef fisheries value using Bureau of Fisheries and Aquatic Resources (BFAR) and literature data, (3) tourism value using Department of Tourism (DOT) and literature data, and (4) Total Economic Value (TEV). The TEV of Philippine reefs' ES amounted to 4 billion US$/yr or 140,000 US$/km2/yr. Furthermore, in each region of the Philippines, annual TEV ranged from 100 to 800 million US$, with potential reef fisheries value contributing the most in the TEV, followed by reef fisheries, tourism, and WTP biodiversity values. In addition, the Visayas regions have the highest values of benefits from coral reefs. Although the Philippines is deriving millions to billions of dollars of economic benefits from coral reefs, the observed degradation and temporal decline in coastal ecosystems could lead to a decline in the potential reef fisheries value, subsequently the TEV. The Philippines need to improve accounting and managing the derived benefits from coral reefs to ensure the sustainability and continuous flow of these benefits for present and future Filipino beneficiaries.

12. Tayaban, K.M.M., Pintor, K.L., Vital, P.G. (2018). Detection of potencial harmful algal bloom-causing microalgae from freshwater prawn farms in Central Luzon, Philippines, for bloom monitoring and prediction. Environment, Developmental and Sustainability, 20 (3), Pages1311-1328. more

Abstract:

Prawn aquaculture industry is one of the developing economic activities in the Philippines. 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.

13. Vital, P.G., Zara, E.S., Paraoan, C.E.M., Dimasupil, M.A.Z., Abello, J.J.M., Santos, I.T.G., Rivera, W.L. (2018). Antibiotic resistance and extended-spectrum beta-lactamase production of Escherichia coli isolated from irrigation waters in selected urban farms in Metro Manila, Philippines. Water, 10 (5), Page 548. more

Abstract:

Highly-polluted surface waters are increasingly used for irrigation in different agricultural settings because they have high nutrient content and are readily available. However, studies showed that they are reservoirs for the emergence and dissemination of antibiotic-resistant bacteria in the environment. In this study, the resistance of 212 Escherichia coli isolates from irrigation water, soil, and vegetables in selected urban farms in Metro Manila, Philippines was evaluated. Results showed that antibiotic resistance was more prevalent in water (67.3%) compared to soil (56.4%) and vegetable (61.5%) isolates. Resistance to tetracycline was the highest among water (45.6%) and vegetable (42.3%) isolates while ampicillin resistance was the highest among soil isolates (33.3%). Multidrug-resistant (MDR) isolates were also observed and they were more prevalent in water (25.3%) compared to soil (2.8%) and vegetable (8.4%) isolates. Interestingly, there are patterns of antibiotic resistance that were common to isolates from different samples. Extended-spectrum beta-lactamase production (ESBL) was also investigated and genes were observed to be present in 13 isolates. This provides circumstantial evidence that highly-polluted surface waters harbor antibiotic-resistant and MDRE. coli that may be potentially transferred to primary production environments during their application for irrigation purposes.

 

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1. Agulto, V.C., Empizo, M.J.F.,  Kawano, K.  Minami, Y., Yamanoi, K., Sarukura, N., Yago, A.C. and  Sarmago, R.V. (2018). Two-step fabrication of ZnO-PVP composites with tunable visible emissionsOptical Materials, 76, Pages 317-322.more

Abstract:

We report a two-step fabrication of zinc oxide-polyvinylpyrrolidone (ZnO-PVP) composites for potential phosphor-based applications. The composites are fabricated by initially preparing ZnO microrods using hydrothermal growth method and then dip-coating the microrods into aqueous PVP solutions with varying molar concentrations. The as-prepared ZnO microrods exhibit smooth surfaces and broad visible emissions, while the ZnO-PVP composites have pitted surfaces with shifted and reduced visible emissions. These changes in the structural and optical properties, which are found to depend on the PVP concentration, are attributed to the adsorption of PVP on the microrod surface. Although the surface morphology and visible emission are modified by PVP, the composites still maintain a hexagonal wurtzite crystal structure and near-band-edge ultraviolet (UV) emission similar with the as-prepared microrods. Our results therefore suggest that the ZnO-PVP composites can be used as phosphors that offer not only properties found in both ZnO and PVP but also tunable visible emissions which can be controlled during material fabrication.

2. Austria, E.S., Nuesca, G.M. and Lamorena, R.B. (2018). Spectral fitting approach for the determination of enrichment and contamination factors in mining sediments using laser-induced breakdown spectroscopy. Environmental Science and Pollution Research, Pages 1-9. more

Abstract:

Monitoring of pollution index values in sediments is crucial in assessing the environmental impacts of toxic metals in a given location. These indices are typically acquired using elaborate and tedious calibration curve-dependent techniques such as (inductively coupled plasma – optical emission spectroscopy) ICP-OES and (atomic absorption spectroscopy) AAS. In this study, laser-induced breakdown spectroscopy (LIBS) was used as a simple and fast alternative method for estimating enrichment factor (EF) and contamination factor (CF) of the sediment samples obtained from selected mining sites. Quantitative analyses of three metal targets (Cd, Pb, and Zn) were done using a calibration-free LIBS method based on the Boltzmann population distribution. Both the EF and CF values calculated from classical ICP-OES method provided significantly high correspondence with the respective EF (R2 = 0.8862–0.9770, p < 0.01–0.05) and CF (R2 = 0.9454–0.9714, p < 0.01) obtained from the developed LIBS method. The intensity-based LIBS approach identified samples AC2 and CCC as the ones with the highest and lowest pollution index values, respectively. The same observation was seen using the concentration-based ICP-OES technique which showed good correlation between the two methods. The correlation results showed the potential of the curve-fitting LIBS analysis in evaluating the level of metal contamination in an area without the preparation of matrix-matched calibration curves.

3. Briones, A.T. and Chichioco-Hernandez, C.L. (2018). Lipase inhibitory activity of Carica papayaChrysophyllum cainitoCorcorus olitoriusCympogon citrates and Syzgium cumini extractsFood Research, 2 (1), Pages 51-55.more

Abstract:

The lipase inhibitory action of Carica papaya, Chrysophyllum cainito, Corcorus olitorius,  Cymbopogon citrates and Syzygium cumini were evaluated to explore for the presence of  anti-obesity compounds and their potential weight-lowering activity. Enzyme inhibition results of the alcoholic extracts of the five plants showed that C. cainito has the highest percent inhibition at 74.91% while S. cumini, C. citratus, C. olitorius and C. papaya obtained less than 50% average inhibition. C. cainito was partitioned using hexane and ethyl acetate to further concentrate the bioactive compounds. The lipase inhibition assay of hexane and ethyl acetate extracts showed 92.11% inhibition and 21.9% inhibition, respectively. The greater activity in the former may imply that majority of potential anti lipase constituents are found in the hexane portion.

4. Denna, M.C.F.J., Camitan, R.A.B., Yabut, D.A., Rivera, B.A. and  Coo, L.dlC. (2018). Determination of Cu (II) in environmental water samples using polymer inclusion membrane- TAC optode in a continuous flow system.  Sensors and Actuators B: Chemical, 260, Pages 445-451.more

Abstract:

This study describes the selective determination of copper (II) using the recently developed polymer inclusion membrane (PIM) in a river water system via a continuous flow (CF) system. The PIM is composed of 42% di(2-ethlyhexyl) phosphoric acid (D2EHPA) as the carrier, 8% dioctyl phthalate (DOP) as the plasticizer and 49% poly(vinyl chloride) (PVC) as the base polymer. The colorimetric reagent that is used for the spectrophotometric determination of copper (II) is 1% 2-(2-thiazolylazo)-p-cresol (TAC). In this system, copper (II) is extracted into the PIM as the copper-D2EHPA complex which afterwards reacts with TAC producing green copper −TAC complex. The quantitative measurements are conducted by using light emitting diode (LED) and light dependent resistor (LDR) connected to a voltmeter. Results are obtained through the voltage readout on the computer. Under optimal conditions, the sensor has a limit of detection (LOD) of 0.10 mg L−1 and a limit of quantitation (LOQ) of 0.35 mg L−1. The CF-PIM-TAC system was successfully used in the determination of Cu(II) in river systems near mining sites.

5. Kue, K.Y., Claudio, G.C. and Hsu, C.P. (2018). Hamiltonian-independent generalization of the fragment excitation difference scheme.  J. Chem. Theory Comput., 14, Pages, 1304−1310. more

Abstract:

The fragment excitation difference (FED) scheme is a useful method for calculating the complete diabatic couplings of various energy transfer systems. The lack of a good definition for the transformation of the transition density matrix to the off-diagonal FED matrix elements limits FED to single-excitation methods. We have developed a generalized FED scheme called the θ-optimized FED (θ-FED) scheme which does not require transforming the transition density matrices. In θ-FED, two states of interest are linearly transformed by a mixing angle θ into two mixed states. The excitation difference of each mixed state is evaluated and optimized numerically to determine the mixing angle. This approach allows for finding diabatic states and the corresponding couplings for a general set of Hamiltonians.

6. Martin, Z.N.Z., Martinez, I.S., and Nellas, R.B. (2018). Surface tension data of n-propane, n-octane and n-dodecane from nucleation simulations. Tellus, Series B: Chemical and Physical Meteorology, 70 (1). more

Abstract:

The Classical Nucleation Theory (CNT) has been a dominant model in understanding the self-assembly of new thermodynamic phases. CNT provides significant explanations to processes such as aerosol formation and cloud condensation. In this work, we generated the nucleation free energy profiles of normal alkanes (n-propane, n-octane and n-dodecane) at five different temperatures using the grand-canonical version of the nucleation algorithm. From these free energy profiles, characteristic   (  ) values were obtained. Using the density,   values from United-Atom Transferable Potentials for Phase Equilibria (TraPPE-UA) force field and the obtained   values, we calculated the corresponding surface tension,   values of these n-alkane systems at different temperatures. Values obtained are within reasonable agreement with experimental data.

7. Salas, R.L., Garcia, J.K.DL, Miranda, A.C.R., Rivera, W.L., Nellas, R.B., and Sabido, P.M.G. (2018). Effects of truncation of the peptide chain on the secondary structure and bioactivities of palmitoylated anoplin. Peptides 104, Pages 7-14. more

Abstract:

Anoplin (GLLKRIKTLL-NH2) is of current interest due to its short sequence and specificity towards bacteria. Recent studies on anoplin have shown that truncation and acylation compromises its antimicrobial activity and specificity, respectively. In this study, truncated analogues (pal-ano-9 to pal-ano-5) of palmitoylated anoplin (pal-anoplin) were synthesized to determine the effects of C-truncation on its bioactivities. Moreover, secondary structure of each analogue using circular dichroism (CD) spectroscopy was determined to correlate with bioactivities. Interestingly, pal-anoplin, pal-ano-9 and pal-ano-6 were helical in water, unlike anoplin. In contrast, pal-ano-8, pal-ano-7 and pal-ano-5, with polar amino acid residues at the C-terminus, were random coil in water. Nevertheless, all the peptides folded into helical structures in 30% trifluoroethanol/water (TFE/H2O) except for the shortest analogue pal-ano-5. Hydrophobicity played a significant role in the enhancement of activity against bacteria E. coli and S. aureus as all lipopeptides including the random coil pal-ano-5 were more active than the parent anoplin. Meanwhile, the greatest improvement in activity against the fungus C. albicans was observed for pal-anoplin analogues (pal-ano-9 and pal-ano-6) that were helical in water. Although, hydrophobicity is a major factor in the secondary structure and antimicrobial activity, it appears that the nature of amino acids at the C-terminus also influence folding of lipopeptides in water and its antifungal activity. Moreover, the hemolytic activity of the analogues was found to correlate with hydrophobicity, except the least hemolytic pal-ano-5. Since most of the analogues are more potent and shorter than anoplin, they are promising drug candidates for further development.

8.Tiongson, J.K.A., Bruzon, D.A.V., Tapang, G.A., and Martinez, I.S. (2018). Syntheses and properties of methoxy and nitrile functionalized imidazolium tris(pentafluoroethyl) trifluorophosphate ionic liquids. Journal of Chemical and Engineering Data, 63 (5), Pages 1135-1145. more

Abstract:

An alternative and more benign method was employed to synthesize tris(pentafluoroethyl)trifluorophosphate (FAP) ionic liquids (ILs). Ion exchange chromatography was used instead of the typical electrochemical fluorination developed by Ignat'ev and co-workers. The resulting procedure is simple and can be readily performed, as the use of corrosive hydrofluoric acid and the production of toxic and explosive byproducts were circumvented. Functionalization of the alkyl group of the imidazolium cation with a methoxy and a nitrile moiety was employed to observe changes in properties. The success of the synthesis was confirmed by 1H, 19F, and 31P NMR, IR, and UV-vis spectroscopy techniques. Quantitative product yields of approximately 80% (w/w) were obtained. The water content and viscosity values of the synthesized FAP-based ILs were found to be lower compared to other fluorine-containing ionic liquids. Thermal analyses resulted in high thermal degradation temperatures greater than 573.15 K. Electrochemical analyses showed potential windows of values greater than 5.0 V, indicating electrochemical stability. On the basis of the basic properties observed, the FAP-based ILs synthesized in this study may be useful as gas absorbents, electrolytes, and other applications, especially those involving extended temperature ranges.

9. Tutor, J.T. and Chichioco-Hernandez, C.L. (2018). Angiotensin-converting enzyme inhibition of fractions from Eleusine indica leaf extractsPharmacogn J., 10 (1), Pages 25-28. more

Abstract:

Solvent fractions and decoction of Eleusine indica leaves were tested for their ability to inhibit angiotensin-converting enzyme (ACE), an important component of the Renin-Angiotensin- Aldosterone System which is a critical regulator of arterial blood pressure. The ACE inhibitory activity of each fraction was measured by employing a colorimetric assay based on the hydrolysis of histidyl-hippuryl-leucine (HHL) by ACE. Preliminary assay results revealed that the ethyl acetate fraction exhibited the highest antihypertensive activity with a percent inhibition of 51.51%. This fraction was considered for further isolation using a bioassay-guided fractionation scheme. 

10. Zulueta, M.M.L., Chyan, C.L. and Hung, S.C. (2018). Structural analysis of synthetic heparan sulfate oligosaccharides with fibroblast growth factors and heparin-binding hemagglutininCurrent Opinion in Structural Biology, 50, Pages 126-133.more

Abstract:

Heparan sulfate interacts with a variety of proteins at the cell surface. These proteins are primarily attracted to the high negative charge distribution brought by sulfate, sulfamate, and carboxylate functionalities along the sugar chain. Apart from electrostatic interactions, hydrogen bonding and even hydrophobic interactions contribute to the complex formation. While additional sulfate/sulfamate groups are often tolerated as long as the main structural requirements are met, occasionally, certain extra sulfate groups may be detrimental to the binding affinity. Here, we show these binding characteristics using the binding of fibroblast growth factors and heparin-binding hemagglutinin to synthetic heparan sulfate oligosaccharides as examples. Insights into the binding characteristics of these proteins may benefit future therapeutic interventions.

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1. Bagtasa, G., Cayetano, M.G., Yuan, C.-S. (2018). Seasonal variation and chemical characterization of PM2.5 in northwestern Philippines. Atmospheric Chemistry and Physics, 18 (7), Pages 4965-4980. more

Abstract:

The seasonal and chemical characteristics of fine particulate matter (PM2.5) were investigated in Burgos, Ilocos Norte, located at the northwestern edge of the Philippines. Each 24gh sample of fine aerosol was collected for four seasons. Fine particulate in the region shows strong seasonal variation in both concentration and composition. Highest mass concentration was seen during the boreal spring season with a mean mass concentration of 21.6g±g6.6g3, and lowest was in fall with a mean concentration of 8.4g±g2.3g3. Three-day wind back trajectory analysis of air mass reveals the influence of the northwestern Pacific monsoon regimes on PM2.5 concentration. During southwest monsoon, sea salt was the dominant component of fine aerosols carried by moist air from the South China Sea. During northeast monsoon, on the other hand, both wind and receptor model analysis showed that higher particulate concentration was due to the long-range transport (LRT) of anthropogenic emissions from northern East Asia. Overall, sea salt and soil comprise 33g% of total PM2.5 concentration, while local biomass burning makes up 33g%. LRT of industrial emission, solid waste burning and secondary sulfate from East Asia have a mean contribution of 34g% to the total fine particulate for the whole sampling period.

2. Ishida, T., Kurihara, J., Viray, F.A., Namuco, S.B., Paringit, E.C., Perez, G.J., Takahashi, Y., Marciano, J.J., Jr. (2018). A novel approach for vegetation classification using UAV-based hyperspectral imagingComputers and Electronics in Agriculture, Volume 144, Pages 80-85.more

Abstract:

The use of unmanned aerial vehicle (UAV)-based spectral imaging offers considerable advantages in high-resolution remote-sensing applications. However, the number of sensors mountable on a UAV is limited, and selecting the optimal combination of spectral bands is complex but crucial for conventional UAV-based multi spectral imaging systems. To overcome these limitations, we adopted a liquid crystal tunable filter (LCTF), which can transmit selected wavelengths without the need to exchange optical filters. For calibration and validation of the LCTF-based hyperspectral imaging system, a field campaign was conducted in the Philippines during March 28-April 3, 2016. In this campaign, UAV-based hyperspectral imaging was performed in several vegetated areas, and the spectral reflectances of 14 different ground objects were measured. Additionally, the machine learning (ML) approach using a support vector machine (SVM) model was applied to the obtained dataset, and a high resolution classification map was then produced from the aerial hyperspectral images. The results clearly showed that a large amount of misclassification occurred in shaded areas due to the difference in spectral reflectance between sunlit and shaded areas. It was also found that the classification accuracy was drastically improved by training the SVM model with both sunlit and shaded spectral data. As a result, we achieved a classification accuracy of 94.5% in vegetated areas.

3. Rodrigo, S.M.T., Villanoy, C.L., Briones, J.C., Bilgera, P.H.T., Cabrera, O.C., Narisma, G.T.T. (2018). The mapping of storm surge-prone areas and characterizing surge-producing cyclones in Leyte Gulf, PhilippinesNatural Hazards, Pages 1-16. more

Abstract:

Historically, Leyte Gulf in central eastern Philippines has received catastrophic damage due to storm surges, the most recent of which was during Typhoon Haiyan in 2013. A city-level risk assessment was performed on Leyte Gulf through synthetic storm generation, high-resolution ocean modeling, and decision tree analyses. Cyclones were generated through a combination of a Poisson point process and Monte Carlo simulations. Wind and pressure fields generated from the cyclones were used in a storm surge model of Leyte Gulf developed on Delft3D. The output of these simulations was a synthetic record of extreme sea level events, which were used to estimate maximum surge heights for different return periods and to characterize surge-producing storm characteristics using decision tree analyses. The results showed that the area most prone to surges is the Tacloban–Basey area with a 2.8 ± 0.3 m surge occurring at a frequency of every 50 years. Nearby Palo area will likely receive a surge of 1.9 ± 0.4 m every 50 years while Giporlos–Salcedo area a surge of 1.0 ± 0.1 m. The decision tree analysis performed for each of these areas showed that for surges of 3–4 m, high-velocity winds (> 30 m/s) are consistently the main determining factor. For the areas, Tacloban, Basey, and Giporlos–Salcedo, wind speed was also the main determining factor for surge > 4 m.

 

IM

1. Agong, Louis Anthony; Amarra, Carmen; Caughman, John S.; Herman, AJ (Herman, Ari J). (2018). On the girth and diameter of generalized Johnson graphs.  Discrete Mathematics, 341 (1), Pages 138-142.more

Abstract:

Let v > k > i be non-negative integers. The generalized Johnson graph, J(v, k, i), is the graph whose vertices are the k-subsets of a v-set, where vertices A and B are adjacent whenever vertical bar A boolean AND B vertical bar = i. In this article, we derive general formulas for the girth and diameter of J(v, k, i). Additionally, we provide a formula for the distance between any two vertices A and B in terms of the cardinality of their intersection.

2. Arceo, C.P.P., Jose, E.C., Lao, A.R., Mendoza, E.R. (2018). Reactant subspaces and kinetics of chemical reaction networksJournal of Mathematical Chemistry, 56 (2), Pages 395-422.more

Abstract:

This paper studies a chemical reaction network’s (CRN) reactant subspace, i.e. the linear subspace generated by its reactant complexes, to elucidate its role in the system’s kinetic behaviour. We introduce concepts such as reactant rank and reactant deficiency and compare them with their analogues currently used in chemical reaction network theory. We construct a classification of CRNs based on the type of intersection between the reactant subspace R and the stoichiometric subspace S and identify the subnetwork of S-complexes, i.e. complexes which, when viewed as vectors, are contained in S, as a tool to study the network classes, which play a key role in the kinetic behaviour. Our main results on new connections between reactant subspaces and kinetic properties are (1) determination of kinetic characteristics of CRNs with zero reactant deficiency by considering the difference between (network) deficiency and reactant deficiency, (2) resolution of the coincidence problem between the reactant and kinetic subspaces for complex factorizable kinetics via an analogue of the generalized Feinberg–Horn theorem, and (3) construction of an appropriate subspace for the parametrization and uniqueness of positive equilibria for complex factorizable power law kinetics, extending the work of Müller and Regensburger.

3. Cortez, Mark Jayson, Nazareno, Allen Lamarca, Mendoza, Eduardo R.  (2018). A computational approach to linear conjugacy in a class of power law kinetic systemsJournal of Mathematical Chemistry, 56 (2 & 1), Pages 336-357.  more

 

Abstract:

This paper studies linear conjugacy of PL-RDK systems, which are kinetic systems with power law rate functions whose kinetic orders are identical for branching reactions, i.e. reactions with the same reactant complex. Mass action kinetics (MAK) systems are the best known examples of such systems with reactant-determined kinetic orders (RDK). We specify their kinetics with their rate vector and T matrix. The T matrix is formed from the kinetic order matrix by replacing the reactions with their reactant complexes as row indices (thus compressing identical rows of branching reactions of a reactant complex to one) and taking the transpose of the resulting matrix. The T matrix is hence the kinetic analogue of the network’s matrix of complexes Y with the latter’s columns of non-reactant complexes truncated away. For MAK systems, the T matrix and the truncated Y matrix are identical. We show that, on non-branching networks, a necessary condition for linear conjugacy of MAK systems and, more generally, of PL-FSK (power law factor span surjective kinetics) systems, i.e. those whose T matrix columns are pairwise different, is T= T′, i.e. equality of their T matrices. This motivated our inclusion of the condition T= T′ in exploring extension of results from MAK to PL-RDK systems. We extend the Johnston–Siegel Criterion for linear conjugacy from MAK to PL-RDK systems satisfying the additional assumption of T= T′ and adapt the MILP algorithms of Johnston et al. and Szederkenyi to search for linear conjugates of such systems. We conclude by illustrating the results with several examples and an outlook on further research.

4. de la Cruz, R.J., Granario, D.Q. (2018). Products of symplectic normal matricesLinear Algebra and Its Applications, 543, Pages 162-172.more

Abstract:

A matrix A∈M2n(C) is symplectic if AT[0In−In0]A=[0In−In0]. We show that every symplectic matrix is a product of a symplectic unitary and a symplectic skew-Hermitian matrix. We show that every symplectic matrix is a product of four symplectic skew-Hermitian matrices or a product of four symplectic Hermitian matrices. We give the possible Jordan canonical forms of symplectic matrices which can be written as a product of a symplectic Hermitian and a matrix which is either symplectic Hermitian or symplectic skew-Hermitian.

5. Dela Rosa, K.L., Merino, D.I., Paras, A.T. (2018). The subspaces spanned by Householder vectors associated with an orthogonal or a symplectic matrixLinear Algebra and Its Applications, 546, Pages 37-49.more

Abstract:

The Cartan–Dieudonné–Scherk Theorem guarantees that every complex orthogonal matrix can be written as a product of matrices of the form HS,u≡I−uuTS, where S=I and uCn satisfies uTu=2; moreover, every complex symplectic matrix can be written as a product of matrices of the form HS,u≡I−uuTS where S=J=[0I−I0] and u≠0. Let a nonempty VCn be given. The S-orthogonal complement of V is VS={zCn | wTSz=0 for all wV}. The image of an n-by-n complex matrix A is the set of all zCn for which there is an xCn such that z=Ax and is denoted by Im(A). Let S=I or S=J. Suppose that Q=HS,u1HS,u2HS,ur. Set U=span{u1,u2,…,ur}. We study the relationship between Q, U, and Im(Q−I). Suppose that r is minimal. We show that if dim(U)=r, then Im(Q−I)=U. We also show that S(Q−I) is not skew symmetric if and only if dim(U)=r. Let W=Im(Q−I). We show that a relationship between W and WS determines the Jordan structure of Q, in particular, we show that (Q−I)2=0 if and only if WWS.

6. Kim, S., de los Reyes, A.A., Jung, E.  (2018). Mathematical model and intervention strategies for mitigating tuberculosis in the Philippines. Journal of Theoretical Biology, 443 (14), Pages 100-112. more

Abstract:

Tuberculosis (TB) is the sixth leading cause of morbidity and mortality in the Philippines. Although significant progress has been made in the detection and cure of TB under the Directly Observed Treatment Short Course, battling against the disease is still a burdensome task. It demands a concerted effort for specific and effective interventions. In this work, a mathematical TB model fitted to the Philippine data is developed to understand its transmission dynamics. Different control strategies such as distancing, latent case finding, case holding, active case finding controls, and combinations thereof are investigated within the framework of optimal control theory. This study proposes optimal control strategies for reducing the number of high-risk latent and infectious TB patients with minimum intervention implementation costs. Results suggest that distancing control is the most efficient control strategy when a single intervention is utilized. However, full scale employment of the distancing control measure is a daunting task. This burden can be circumvented by the combination of other control interventions. Our noble finding in this study is that enhancing active case finding control instead of case holding control together with distancing and latent case finding control is shown to have significant potential for curtailing the spread of TB in the Philippines.

7. Magdalena, Ikha, Roque, Marian P.  (2018).  Analytical and numerical solution for wave reflection from a porous wave absorberJournal of Physics: Conference Series, 974 (1). more

 

Abstract:

In this paper, wave reflection from a porous wave absorber is investigated theoretically and numerically. The equations that we used are based on shallow water type model. Modification of motion inside the absorber is by including linearized friction term in momentum equation and introducing a filtered velocity. Here, an analytical solution for wave reflection coefficient from a porous wave absorber over a flat bottom is derived. Numerically, we solve the equations using the finite volume method on a staggered grid. To validate our numerical model, comparison of the numerical reflection coefficient is made against the analytical solution. Further, we implement our numerical scheme to study the evolution of surface waves pass through a porous absorber over varied bottom topography.  

8. Talabis, D.A.S.J., Arceo, C.P.P., Mendoza, E.R. (2018). Positive equilibria of a class of power-law kineticsJournal of Mathematical Chemistry, 56 (2), Pages 358-394.more

Abstract:

This paper studies a class of power-law kinetics, PL-ILK, for whose subset, PL-TIK, analogues of the Deficiency Zero Theorem and the Deficiency One Theorem (DOT) for mass action systems are valid. The DOT also includes the necessary and sufficient condition of Boros for uniqueness in the non-weakly reversible case. To our knowledge, this is the first set of kinetics beyond mass action kinetics (MAK) for which the DOT has been shown to be valid. A further interesting property of PL-TIK is a certain “robustness” relative to dependence of linkage classes: existence of a positive equilibrium for each linkage class implies the existence of a positive equilibrium for the whole network. For MAK systems, the PL-ILK property is equivalent to the reactant deficiency of the linkage class containing the zero complex being one, and zero for all other linkage classes. As shown in the Supplementary Materials, an initial survey of MAK and BST systems already reveals numerous examples with PL-ILK kinetics.

 

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1. Dimalanta, C. B., Faustino-Eslava, D. V., Padrones, J. T., Queaño, K. L., Concepcion, R. A. B., Suzuki, S., Yumul, G.P. (2018).Cathaysian slivers in the Philippine island arc: geochronologic and geochemical evidence from sedimentary formations of the west Central PhilippinesAustralian Journal of Earth Sciences, 65 (1), Pages 93-108.

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Abstract:

The use of geodynamic information contained in sedimentary rocks has only recently been extended into the tectonic reconstruction studies of the Philippine archipelago vis-a-vis the rest of the Southeast Asian region. We present here a comparative assessment of clastic units from the western Central Philippines, particularly from the islands of Mindoro, Panay and Palawan, and propose their likely association with sources of Cathaysian origin. Geochronological data from sedimentary formations in the study areas register U-Pb dating peaks at 185-140 Ma, 140-120 Ma and 112-90 Ma. These are similar to those observed of detrital zircons from rocks of Cathaysian origin in Taiwan and Southern China that chronicle the Yanshanian magmatic events. These same formations also record an older intercept at 1.9-1.85 Ga that likely corresponds to a regional continental orogenic episode recorded in the late Paleoproterozoic Cathaysian block. Major (e.g. Al2O3/TiO2) and trace-element (e.g. Y/Ni vs Cr/V) signatures of these sedimentary formations reflect stronger influences from granitic sources than mafic-ultramafic inputs that should otherwise be expected, considering their current oceanic island arc settings. Their La/Th and Th-Co-Zr/10 ratios also reveal continental island arc and active or passive continental margin depositional settings typical of rocks from the Palawan Microcontinental Block. New geochronological and geochemical data from the clastic rocks of northwest Mindoro, in addition to those already published for the other regions of the Palawan Microcontinental Block, provide further evidence for the amalgamation of fragments of Cathaysian origin within the Philippine island arc system.

 

2. Guotana, J. M. R., Payot, B. D., Dimalanta, C. B., Ramos, N. T., Faustino-Eslava, D. V., Queaño, K. L., & Yumul, G.P., J. (2018). 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, 60 (4), Pages 401-417.more

Abstract:

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. Ilao, K., Morley, C. K., Aurelio, M. A. (2018). 3D seismic investigation of the structural and stratigraphic characteristics of the Pagasa Wedge, Southwest Palawan Basin, Philippines, and their tectonic implicationsJournal of Asian Earth Sciences, 154, Pages 213-237.more

Abstract:

The Pagasa Wedge is a poorly imaged deepwater orogenic wedge that has been variously interpreted as representing an accretionary prism, a former accretionary prism modified by thrusting onto a thinned continental margin, and a gravity-driven fold-thrust belt. This study, using 2D and 3D seismic data, together with well information indicates that at least the external part of the wedge is dominantly composed of mass transport complexes, capped by syn-kinematic sediments that have thrusts and normal faults superimposed upon them. Drilling shows that despite stratigraphic repetition of Eocene Middle Miocene units, there is stratigraphic omission of Oligocene and Early Miocene units. This absence suggests that mass transport processes have introduced the Eocene section into the wedge rather than tectonic thrusting. The accretionary prism stage (Oligocene) of the Central Palawan Ophiolite history appears to be marked by predominantly north-vergent deformation. The Deep Regional Unconformity (17 Ma) likely indicates the approximate time when obduction ceased in Palawan. The Pagasa Wedge is a late-stage product of the convergence history that was active in its final phase sometime above the top of the Nido Limestone (16 Ma) and the base of the Tabon Limestone in the Aboabo-A1X well (9 Ma). The top of the wedge is traditionally associated with the Middle Miocene Unconformity (MMU), However the presence of multiple unconformities, diachronous formation tops, local tectonic unconformities and regional diachronous events (e.g. migrating forebulges) all suggest simply giving a single age (or assigning a single unconformity, such as the MMU as defining the top of the Pagasa Wedge is inappropriate. The overall NE-SW trend of the wedge, and the dominant NW transport of structures within the wedge diverge from the more northerly transport direction determined from outcrops in Palawan, and also from the Nido Limestone in the SW part of the Pagasa Wedge. Possibly this NW transport direction is more related to gravity-driven structures responding to uplift of NE-SW Dangerous Grounds margin during the Middle Miocene (related to slab breakoff?) than it is to thrusting rooted in a plate boundary. The final modification of the wedge occurred when the effects of compression deformation on the wedge had largely ended, but gravity processes (in particular mass transport and normal faulting) still operated.

4. Meyer-Dombard, D. R., Casar, C. P., Simon, A.G., Cardace, D., Shrenk, M. O., Arcilla, C. A. (2018). Biofilm formation and potential for iron cycling in sepentinization-influenced ground water of the Zambales and Coast Range ophiolites. Extremophiles, 22 (3), 407-431.more

Abstract:

Terrestrial serpentinizing systems harbor microbial subsurface life. Passive or active microbially mediated iron transformations at alkaline conditions in deep biosphere serpentinizing ecosystems are understudied. We explore these processes in the Zambales (Philippines) and Coast Range (CA, USA) ophiolites, and associated surface ecosystems by probing the relevance of samples acquired at the surface to in situ, subsurface ecosystems, and the nature of microbe–mineral associations in the subsurface. In this pilot study, we use microcosm experiments and batch culturing directed at iron redox transformations to confirm thermodynamically based predictions that iron transformations may be important in subsurface serpentinizing ecosystems. Biofilms formed on rock cores from the Zambales ophiolite on surface and in-pit associations, confirming that organisms from serpentinizing systems can form biofilms in subsurface environments. Analysis by XPS and FTIR confirmed that enrichment culturing utilizing ferric iron growth substrates produced reduced, magnetic solids containing siderite, spinels, and FeO minerals. Microcosms and enrichment cultures supported organisms whose near relatives participate in iron redox transformations. Further, a potential ‘principal’ microbial community common to solid samples in serpentinizing systems was identified. These results indicate collectively that iron redox transformations should be more thoroughly and universally considered when assessing the function of terrestrial subsurface ecosystems driven by serpentinization.

 

5. Pearson, P. N. and IODP Expedition 363 Shipboard Scientific Party … Fernando, A.G.S. (2018). A deep-sea agglutinated foraminifer tube constructed with planktonic foraminifer shells of a single species. Journal of Micropalaeontology, 37, 97-104.more

Abstract:

Agglutinated foraminifera are marine protists that show apparently complex behaviour in constructing their shells, involving selecting suitable sedimentary grains from their environment, manipulating them in three dimensions, and cementing them precisely into position. Here we illustrate a striking and previously undescribed example of complex organisation in fragments of a tube-like foraminifer (questionably assigned to Rhabdammina) from 1466 m water depth on the northwest Australian margin. The tube is constructed from well-cemented siliciclastic grains which form a matrix into which hundreds of planktonic foraminifer shells are regularly spaced in apparently helical bands. These shells are of a single species, Turborotalita clarkei, which has been selected to the exclusion of all other bioclasts. The majority of shells are set horizontally in the matrix with the umbilical side upward. This mode of construction, as is the case with other agglutinated tests, seems to require either an extraordinarily selective trial-and-error process at the site of cementation or an active sensory and decision-making system within the cell.

6. Vacquand, C., Deville, E., Beaumont, V., Guyot, F. Sissmann, O., Pillot, D., Arcilla, C., Prinzhofer, A. (2018). Reduced gas seepages in ophiolitic complexes: evidences for multiple origins of the H2-CH4-N2 gas mixturesGeochimica et Cosmochimica Acta, 223, Pages 437-461.more

Abstract:

This paper proposes a comparative study of reduced gas seepages occurring in ultrabasic to basic rocks outcropping in ophiolitic complexes based on the study of seepages from Oman, the Philippines, Turkey and New Caledonia. This study is based on analyses of the gas chemical composition, noble gases contents, stable isotopes of carbon, hydrogen and nitrogen. These seepages are mostly made of mixtures of three main components which are H2, CH4 and N2 in various proportions. The relative contents of the three main gas components show 4 distinct types of gas mixtures (H2-rich, N2-rich, N2-H2-CH4 and H2-CH4). These types are interpreted as reflecting different zones of gas generation within or below the ophiolitic complexes. In the H2-rich type, associated noble gases display signatures close to the value of air. In addition to the atmospheric component, mantle and crustal contributions are present in the N2-rich, N2-H2-CH4 and H2-CH4 types. H2-bearing gases are either associated with ultra-basic (pH 10–12) spring waters or they seep directly in fracture systems from the ophiolitic rocks. In ophiolitic contexts, ultrabasic rocks provide an adequate environment with available Fe2+ and alkaline conditions that favor H2 production. CH4 is produced either directly by reaction of dissolved CO2 with basic-ultrabasic rocks during the serpentinization process or in a second step by H2-CO2 interaction. H2 is present in the gas when no more carbon is available in the system to generate CH4. The N2-rich type is notably associated with relatively high contents of crustal 4He and in this gas type N2 is interpreted as issued mainly from sediments located below the ophiolitic units.

 

7. Yan, Y., Yao, D., Tian, Z., Huang, C., Chen, W., Santosh, M., Yumul, G. P. Jr., Dimalanta, C. B., Li, Z. (2018). Zircon U-Pb chronology and hf isotope from the Palawan-Mindoro block, Philippines: Implication to provenance and tectonic evolution of the South China Sea. Tectonics, 37 (4), Pages 1063-1076. more

 

Abstract:

The continental margin of Southeast Asia evolved from a dominantly Andean-type active margin during Mesozoic to a Western Pacific-type since Late Cretaceous. With the spreading of the South China Sea, the Palawan-Mindoro Block drifted from mainland Asia and the Cenozoic strata provide an excellent window to gain insights into the tectonic evolution of the margin of Southeast Asia. Here we present U-Pb age and Hf isotopic data on detrital zircon grains from Cenozoic sedimentary rocks in the Palawan-Mindoro Block, Philippines, to evaluate the provenance and tectonic evolution of the South China Sea. Zircon grains in Eocene-Miocene sedimentary rocks from the Palawan-Mindoro Block show a wide range in age from 60 to 2700 Ma, with four major age groups of 80–120 Ma, 160–180 Ma, 1600–2100 Ma, and 2200–2700 Ma. The εHf(t) of the zircon grains of the samples from Mindoro Island range from −39 to +13.7, and similar Hf isotopic composition is recorded in Paleogene and Neogene strata. Zircon U-Pb ages and Hf isotopic data of the Eocene samples from the Palawan-Mindoro Block show a similar pattern with those from Taiwan, which suggests that the Palawan-Mindoro Block was attached to the margin of South China during Late Cretaceous-Eocene times. The difference of zircon U-Pb age composition in the Miocene samples between the Palawan-Mindoro Block and Taiwan reflects southward drifting of the Palawan-Mindoro Block and seafloor spreading of the South China Sea at that time. 

8. Yang, Y.H., Tsai, M.C., Hu, J.C., Aurelio, M.A., Hashimoto, M., Escudero, J.A.P., Su, Z., & Chen Q. (2018). Coseismic slip deficit of the 2017 Mw 6.5 Ormoc earthquake that occurred along a creeping segment and geothermal field of the Philippine Fault. Geophysical Research Letters March 2018.more

Abstract:

Coseismic surface deformation imaged through Interferometric Synthetic Aperture Radar (InSAR) measurements was used to estimate the fault geometry and slip distribution of the 2017 Mw 6.5 Ormoc Earthquake along a creeping segment of the Philippine Fault on Leyte Island. Our best fitting faulting model suggests that the coseismic rupture occurred on a fault plane with high dip angle of 78.5° and strike angle of 325.8°, and the estimated maximum fault slip of 2.3 m is located at 6.5 km east-northeast of the town of Kananga. The recognized insignificant slip in the Tongonan geothermal field zone implies that the plastic behavior caused by high geothermal gradient underneath the Tongonan geothermal field could prevent the coseismic failure in heated rock mass in this zone. The predicted Coulomb failure stress (CFS) change shows that a significant positive CFS change occurred along the SE segment of central Philippine fault with insignificant coseismic slip and infrequent aftershocks, which suggests an increasing risk for future seismic hazard. 

 

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1. Bascos, N.A.D., Emralino, F.L.C., Liu, F.C., Conception, C.P., Altamia, M., Huang, Y.C., Hsieh, Y.C., Chen, C.J., Palmes-Saloma, C. (2018). Biophysical and functional characterization of asFP504, a novel fluorescent protein from the PhilippinesPhilippine Journal of Science, 147 (1), Pages 65-74.  more

Abstract:

Fluorescent proteins have proven to be invaluable for a myriad of applications in scientific research. The discovery and characterization of novel fluorescent proteins promises to expand this range even further.  This report focuses on the biophysical and functional characterization of a novel green fluorescent protein cloned from a Philippine soft coral species. The asFP504 protein showed peak excitation at 471 nm and at 494 nm (λE1= 471 nm; λE2=494 nm), its emission maximum from 471 nm excitation was observed at 504 nm. The fluorescence was observed to be related to its oligomeric state.  Both fluorescence and oligomerization were robustly maintained for a range of temperatures, pH conditions, treatment with chaotropic agents, and proteolysis. X-ray crystallography documented a molecular packing of three dimers within each asymmetric unit for the asFP504 protein. The observed absorbance and fluorescence properties are comparable to that of commercially available fluorescence proteins. Despite its lower absorbance, asFP504 has higher quantum yield than mCitrine. In addition, the stability of asFP504 in the presence of multiple denaturants presents the potential of this protein – the first fluorescent protein from the Philippines – for use in many different research applications.

2. Dumilag, R.V., Monotilla, W.D. (2018). Molecular diversity and biogeography of Philippine foliose Bangiales (Rhodophyta)Journal of Applied Phycology, 30 (1), Pages 173-186.more

Abstract:

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.

3. Malit, J.J.L. and Hedreyda, C.T. (2018). Detection and Sequence Analysis of Enzyme Genes of Four Thermo-tolerant Bacillus pumilus Strains from the PhilippinesPhilippine Journal of Science, 147 (2).more

Abstract:

The Philippines boasts of diversity in bacterial species that can be explored in producing industrially significant enzymes to help reduce the country’s dependence on enzyme importation. This study was focused on four thermotolerant strains of Bacillus pumilus, a species reported to produce serine alkaline protease, lipase, pectate lyase, and laccase. Enzyme gene targeted polymerase chain reaction (PCR) and gene sequence analysis confirmed the presence of four enzyme genes in all strains studied.  Preliminary enzyme assays revealed that all strains except 1271, tested positive for protease, pectate lyase, and lipase activities. Only strain 1271, however, exhibited positive laccase activity.  These initial results could be the basis for pursuing studies on laccase using strain 1271 and studies on protease, pectate lyase and lipase enzymes from the other three strains. Partial amino acid sequence of the serine alkaline protease gene in strain 1271 revealed five amino acid variations from the other three strains and the variations resulted in protein conformational changes. The translated partial laccase gene sequence of strain 1271 exhibited ten amino acid variations from partial laccase enzymes of the other three strains but the amino acid variations did not result in enzyme conformation change. The amino acid sequences in the complete lipase genes showed five amino acid variations in isolate 1271 compared with enzymes from other three strains but no change in the predicted protein model was observed. Sixteen variations in the amino acid sequences of the pectate lyase enzyme observed among strains resulted in a unique pectate lyase protein conformation for each isolate. The role of enzyme conformation variation as well as other factors that could have led to the enzyme assay results in this study, could be further elucidated with optimized quantitative enzyme assays, gene expression studies and mutagenesis.

4. Perera, D.,  Magbanua, Z.V.,  Thummasuwan, S.,  Mukherjee, D.,  Arick, M., II,  Chouvarine, P.,  Nairn, C.J.,  Schmutz, J.,  Grimwood, J.,  Dean, J.F.D.,  Peterson, D.G. (2018). Exploring the loblolly pine (Pinus taeda L.) genome by BAC sequencing and Cot analysisGene, 663, Pages 165-177.more

Abstract:

Loblolly pine (LP; Pinus taeda L.) is an economically and ecologically important tree in the southeastern U.S. To advance understanding of the loblolly pine (LP; Pinus taeda L.) genome, we sequenced and analyzed 100 BAC clones and performed a Cot analysis. The Cot analysis indicates that the genome is composed of 57, 24, and 10% highly-repetitive, moderately-repetitive, and single/low-copy sequences, respectively (the remaining 9% of the genome is a combination of fold back and damaged DNA). Although single/low-copy DNA only accounts for 10% of the LP genome, the amount of single/low-copy DNA in LP is still 14 times the size of the Arabidopsis genome. Since gene numbers in LP are similar to those in Arabidopsis, much of the single/low-copy DNA of LP would appear to be composed of DNA that is both gene- and repeat-poor. Macroarrays prepared from a LP bacterial artificial chromosome (BAC) library were hybridized with probes designed from cell wall synthesis/wood development cDNAs, and 50 of the “targeted” clones were selected for further analysis. An additional 25 clones were selected because they contained few repeats, while 25 more clones were selected at random. The 100 BAC clones were Sanger sequenced and assembled. Of the targeted BACs, 80% contained all or part of the cDNA used to target them. One targeted BAC was found to contain fungal DNA and was eliminated from further analysis. Combinations of similarity-based and ab initio gene prediction approaches were utilized to identify and characterize potential coding regions in the 99 BACs containing LP DNA. From this analysis, we identified 154 gene models (GMs) representing both putative protein-coding genes and likely pseudogenes. Ten of the GMs (all of which were specifically targeted) had enough support to be classified as intact genes. Interestingly, the 154 GMs had statistically indistinguishable (α = 0.05) distributions in the targeted and random BAC clones (15.18 and 12.61 GM/Mb, respectively), whereas the low-repeat BACs contained significantly fewer GMs (7.08 GM/Mb). However, when GM length was considered, the targeted BACs had a significantly greater percentage of their length in GMs (3.26%) when compared to random (1.63%) and low-repeat (0.62%) BACs. The results of our study provide insight into LP evolution and inform ongoing efforts to produce a reference genome sequence for LP, while characterization of genes involved in cell wall production highlights carbon metabolism pathways that can be leveraged for increasing wood production.

5. Vasquez, M.R., Jr.,  Prieto, E.I.,  Wada, M. (2018). Radio-frequency plasma-induced biocompatibility of polyimide substratesPlasma Medicine, 8 (1), Pages 35-44.more

Abstract:

Surfaces of polyimide (PI) sheets were modified using 13.56-MHz radio-frequency discharges to enhance their affinity with fibroblast cells. Physico-chemical analysis of pristine and plasma-treated PI sheets showed different responses against argon (Ar), oxygen (O2), and nitrogen (N2) as the plasma process gases. Overall, hydrophilicity of treated PI surfaces was enhanced, and its surface free energy increased from 53 dyn/cm to at least 73 dyn/ cm. Surface roughness values also increased from 1.3 to 40.8 nm, as demonstrated by atomic force microscopy analyses. Infrared spectral analyses showed a decrease of imide functional group peak intensities on plasma exposure, corresponding to chemical surface structural changes. In addition, plasma-treated surfaces significantly increased cell adhesion and proliferation compared to pristine samples. N2-containing plasma exhibited the greatest increase among the test gases, due to the possible inclusion of N2-based functional groups that enhance biochemical affinity of fibroblast cells.

 

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1. Agulto, V.C., Empizo, M.J.F.,  Kawano, K.  Minami, Y., Yamanoi, K., Sarukura, N., Yago, A.C. and  Sarmago, R.V. (2018). Two-step fabrication of ZnO-PVP composites with tunable visible emissionsOptical Materials, 76, Pages 317-322.more

Abstract:

We report a two-step fabrication of zinc oxide-polyvinylpyrrolidone (ZnO-PVP) composites for potential phosphor-based applications. The composites are fabricated by initially preparing ZnO microrods using hydrothermal growth method and then dip-coating the microrods into aqueous PVP solutions with varying molar concentrations. The as-prepared ZnO microrods exhibit smooth surfaces and broad visible emissions, while the ZnO-PVP composites have pitted surfaces with shifted and reduced visible emissions. These changes in the structural and optical properties, which are found to depend on the PVP concentration, are attributed to the adsorption of PVP on the microrod surface. Although the surface morphology and visible emission are modified by PVP, the composites still maintain a hexagonal wurtzite crystal structure and near-band-edge ultraviolet (UV) emission similar with the as-prepared microrods. Our results therefore suggest that the ZnO-PVP composites can be used as phosphors that offer not only properties found in both ZnO and PVP but also tunable visible emissions which can be controlled during material fabrication.

2. Dasallas, L.L.Garcia, W.O. (2018). Numerical simulation of femtosecond pulsed laser ablation of copper for oblique angle of incidence through two-temperature modelMaterials Research Express, 5 (1).more

Abstract:

We propose a numerical model to describe laser ablation of a copper target by a femtosecond laser pulse at an oblique angle of incidence. The model is based on the two temperature model and improved to include laser fluence, laser spot size, and dynamic changes in reflectivity of the target. Numerical results show that the electron and lattice temperatures decrease with the angle of incidence. The dependency of the maximum temperature with angle of incidence follow a cosine power law. The threshold laser fluence, ablation depth and crater size depend on the polarization and angle of the incident laser beam. Our model is supported by the experimental results reported by other group working in femtosecond pulsed laser ablation. 

3. Dasallas, L.L., Jaculbia, R.B., Balois, M.V., Garcia, W.O., Hayazawa, N. (2018). Position, orientation, and relative quantum yield ratio determination of fluorescent nanoemitters via combined laser scanning microscopy and polarization measurements. Optical Materials Express, 8 (5), Pages 1290-1304. more

 

Abstract:

We present a universal method of determining the position, 3D orientation, and relative quantum yield ratio (RQYR) of fluorescent nanoemitters (ZnS coated CdSe quantum dots) in a glass slide by combining laser scanning microscopy (LSM) and polarization measurements. The quantum dots were located through LSM intensity maps using azimuthal, radial, and linear incident polarizations. LSM imaging was not sufficient to determine the orientation of the quantum dots due to the isotropic absorption dipole moment. The 3D orientation was obtained through polarization measurement. By combining LSM and polarization measurements, the RQYR of a single molecule was evaluated, allowing us to compare the quantum yield of the nanoemitters. 

4. De Vero, J.C., Lee, D., Shin, H., Namuco, S.B., Hwang, I., Sarmago, R.V., Song, J.H. (2018). Influence of deposition conditions on the growth of micron-thick highly c-axis textured superconducting GdBa2Cu3O7-δ films on SrTiO3 (100). Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films, 36 (3). 

Abstract:

A fundamental understanding of film processing conditions and its effect on the microstructure, crystallinity, and electrical properties of thick layers of a GdBa2Cu3O7-δ (GdBaCuO) superconductor is necessary to optimize material requirements for its applications. In this work, the authors investigated the surface microstructure, crystalline quality, and superconducting properties of GdBaCuO thick films on (100) SrTiO3 single crystal substrates prepared by pulsed laser deposition (PLD). To clarify the effect of PLD growth conditions the substrate temperature, oxygen partial pressure, and laser fluence were systematically varied, then their impact was correlated on the microstructure and superconducting properties of thick layers of GdBaCuO films. By optimizing these growth conditions, the authors successfully obtained preferentially c-axis textured and superconducting films with a uniform and homogeneous layer up to 3.8 μm thick. Based on these results, the authors provide a key guiding principle in achieving thick highly c-axis textured superconducting GdBaCuO films using PLD.

5. delos Santos, R., Mag-usara, V., Tuico, A., Copa, V., Salvador, A., Yamamoto, K., Somintac, A., Kurihara, K., Kitahara, H., Tani, M., Estacio, E.  (2018). Metal-Coated <100>-Cut GaAs Coupled to Tapered Parallel-Plate Waveguide for Cherenkov-Phase-Matched Terahertz Detection: Influence of Crystal Thickness. Journal of Infrared, Millimeter, and Terahertz Waves, 39(6), Pages 514-520. more

 

Abstract:

The influence of crystal thickness of metal-coated <100>-cut GaAs (M-G-M) on Cherenkov-phase-matched terahertz (THz) pulse detection was studied. The M-G-M detectors were utilized in conjunction with a metallic tapered parallel-plate waveguide (TPPWG). Polarization-sensitive measurements were carried out to exemplify the efficacy of GaAs in detecting transverse magnetic (TM)- and transverse electric (TE)-polarized THz waves. The reduction of GaAs’ thickness increased the THz amplitude spectra of the detected TM-polarized THz electro-optic (EO) signal due to enhanced electric field associated with a more tightly-focused and well-concentrated THz radiation on the thinner M-G-M. The higher-fluence THz beam coupled to the thinner M-G-M improved the integrated intensity of the detected THz amplitude spectrum. This trend was not observed for TE-polarized THz waves, wherein the integrated intensities were almost comparable. Nevertheless, good agreement of spectral line shapes of the superposed TM- and TE-polarized THz-EO signals with that of elliptically polarized THz-EO signal demonstrates excellent polarization-resolved detection capabilities of M-G-M via Cherenkov-phase-matched EO sampling technique. 

6. Gabriel, A.A., Ballesteros, M.L.P., Rosario, L.M.D., Tumlos,R.B., Ramos, H.J. (2018). Elimination of Salmonella enterica on common stainless steel food contact surfaces using UV-C and atmospheric pressure plasma jetFood Control, 86, Pages 90-100.more

Abstract: 

This study aimed to evaluate the efficacy of ultraviolet-C irradiation and atmospheric pressure plasma jet treatment as inactivation methods of Salmonella spp. on stainless steel surfaces commonly used as food contact surfaces. Two types of stainless steel namely 304 and 316, were used as test surfaces with each type having three different finishes: 2B, Hair line (HL), and Mirror (MR). A cocktail of 7 serovars of S. enterica at mid stationary phase (17 h) cells were allowed to adhere onto the surfaces (4h) prior to UV-C and plasma treatment. Results showed that the test organism exhibited a biphasic UV-C inactivation composed of a fast log linear inactivation phase followed by a slower inactivation tail on all test surfaces. The D values calculated from the faster log linear inactivation phase ranged from 2.54 (316 2B and 316 HL) to 4.31 s (304 2B). The maximum population reduction calculated before the inactivation tail ranged from 3.32 (316 HL) to 4.97 log CFU/in2 (304 MR). Plasma treatment of metal surfaces resulted in abrupt increase in surface temperature, reaching up to 180 °C within 15 s of treatment, and led to log linear inactivation in all surfaces treated with atmospheric plasma jet. The D values ranged from 2.66 (304 2B) to 3.43 s (316 MR). Both metal type and surface finish were observed not to affect the efficacies of UV-C inactivation and atmospheric pressure plasma jet treatment. The results obtained in the study demonstrated the potential of the tested physical treatments as alternatives to commonly used food contact surface chemical sanitation protocols.

7. Sadiaa, C.P., Lopez Jr., L.P., delos Santos, R.M., Muldera, J.E., De Los Reyes, A.E.,Tumanguil, M.A.C., Que, C.T., Mag-usara,V.K., Tani, M., Somintac, A.S., Estacio, E.S., Salvador, A.S. (2018). Epitaxial growth of p-InAs on GaSb with intense terahertz emission under 1.55- μ m femtosecond laser excitationThin Solid Films, 648, Pages 46-49.more

Abstract: 

We report the molecular beam epitaxy growth of high-quality p-InAs thin films evaluated in the context of 1.55 μm femtosecond laser-excited THz emission efficiency. The presence of p-InAs is confirmed via scanning electron microscopy and X-ray diffraction. Using a GaAs buffer layer, the epitaxial growth of p-InAs layers was successfully achieved. Initiating GaAs deposition by growth interruption, we find that GaAs adheres to the GaSb substrate and provides a quasi-planar surface for the subsequent layers. We also find a significant enhancement in the THz radiation intensity of p-InAs films that is approximately twice compared to that of bulk p-InAs for 1.55 μm wavelength.

8. Tica, C.D., Galapon, E.A. (2018). Finite-part integration of the generalized Stieltjes transform and its dominant asymptotic behavior for small values of the parameter. I. Integer ordersJournal of Mathematical Physics, 59 (2).

Abstract:

The paper addresses the exact evaluation of the generalized Stieltjes transform Sn[f]=0 f(x)(ω+x)-ndx of integral order n = 1, 2, 3,  about ω = 0 from which the asymptotic behavior of Sn[f] for small parameters ω is directly extracted. An attempt to evaluate the integral by expanding the integrand (ω + x)-n about ω = 0 and then naively integrating the resulting infinite series term by term leads to an infinite series whose terms are divergent integrals. Assigning values to the divergent integrals, say, by analytic continuation or by Hadamard's finite part is known to reproduce only some of the correct terms of the expansion but completely misses out a group of terms. Here we evaluate explicitly the generalized Stieltjes transform by means of finite-part integration recently introduced in Galapon [Proc. R. Soc. A 473, 20160567 (2017)]. It is shown that, when f(x) does not vanish or has zero of order m at the origin such that (n - m) ≥ 1, the dominant terms of Sn[f] as ω → 0 come from contributions arising from the poles and branch points of the complex valued function f(z)(ω + z)-n. These dominant terms are precisely the terms missed out by naive term by term integration. Furthermore, it is demonstrated how finite-part integration leads to new series representations of special functions by exploiting their known Stieltjes integral representations. Finally, the application of finite part integration in obtaining asymptotic expansions of the effective diffusivity in the limit of high Peclet number, the Green-Kubo formula for the self-diffusion coefficient, and the antisymmetric part of the diffusion tensor in the weak noise limit is discussed.

9. Tionon, J.K.A., Bruzon, D.A.V., Tapang, G.A., Martinez, I.S. (2018). Syntheses and Properties of Methoxy and Nitrile Functionalized Imidazolium Tris(pentafluoroethyl)trifluorophosphate Ionic Liquids. Journal of Chemical and Engineering Data, 63 (5), Pages 1135-1145. more

Abstract:

An alternative and more benign method was employed to synthesize tris(pentafluoroethyl)trifluorophosphate (FAP) ionic liquids (ILs). Ion exchange chromatography was used instead of the typical electrochemical fluorination developed by Ignat'ev and co-workers. The resulting procedure is simple and can be readily performed, as the use of corrosive hydrofluoric acid and the production of toxic and explosive byproducts were circumvented. Functionalization of the alkyl group of the imidazolium cation with a methoxy and a nitrile moiety was employed to observe changes in properties. The success of the synthesis was confirmed by 1H, 19F, and 31P NMR, IR, and UV-vis spectroscopy techniques. Quantitative product yields of approximately 80% (w/w) were obtained. The water content and viscosity values of the synthesized FAP-based ILs were found to be lower compared to other fluorine-containing ionic liquids. Thermal analyses resulted in high thermal degradation temperatures greater than 573.15 K. Electrochemical analyses showed potential windows of values greater than 5.0 V, indicating electrochemical stability. On the basis of the basic properties observed, the FAP-based ILs synthesized in this study may be useful as gas absorbents, electrolytes, and other applications, especially those involving extended temperature ranges.