Publications

Physically crosslinked superabsorbent hydrogels based on NaCMC, HPC, and NaAlg were developed to address the effects of water shortage to crop farming and to regulate fertilizer usage. An optimized synthesis was performed using ten different blends. The blend with a NaCMC/HPC/NaAlg ratio of 0.29/0.42/0.29 was found to exhibit the most favorable results, accommodating 1585% moisture and 8.38% fertilizer on a dry basis. Scanning electron microscope images of this blend manifested microporous structures, responsible for its superabsorbent properties. It was found out that applying the hydrogel at 5% loading to silt soil decreases fertilizer runoff by 28% and increases field capacity to 55%. Moreover, phytotoxicity studies showed that the optimum hydrogel blend exhibits no phytotoxic properties to pechay (Brassica rapa subsp. chinensis), lettuce eton (Lactuca sativa), and spinach (Spinacia oleracea), proving its applicability to agriculture.

Plasma-activated zeolites were used in the removal of diclofenac sodium (DCF) via adsorption in an aqueous solution. The natural zeolites were exposed to 13.56 MHz radio frequency-driven plasma discharge using argon as the working gas. Results have shown an increase in adsorption capacity of DCF to 64% from 52% using the plasma-treated and untreated zeolites, respectively. Further analysis showed no significant changes in the bulk properties of the zeolite after plasma exposure. However, an apparent increase in surface porosity was observed after treatment due to etching and ablation effects of the impinging energetic particles from the discharge. The adsorption of DCF followed the Freundlich isotherm model suggesting that the modified surface is heterogeneous allowing multilayer adsorption. This work realized the enhancement of adsorption capacity of natural zeolites via plasma treatment. The plasma-treated zeolites are inexpensive candidates for the removal of emerging pharmaceutical wastes in wastewater such as DCF.

Copper (Cu) ions were successfully loaded in a bentonite matrix via ion-exchange method producing the Cu-Bentonite nanocomposites. Samples were treated using 13.56 MHz radio frequency (RF) plasma system with argon (Ar) and oxygen (O2) gases at varying input power (30 and 80 W) and constant treatment time of 10 min. X-ray diffraction patterns revealed the presence of Cu metal after the plasma treatment of samples. SEM images confirmed the changes onthe surface of the nanocomposites after plasma treatment. The untreated and treated Cu-bentonite nanocomposites showed effective antibacterial activity against E. coli and S. aureus. The nanocomposite can be used for biological as well as biomedical applications due to its antibacterial capabilities.

The essay is a general overview of the Philippine Performance Archive on Cultural Performances. The first part is an introduction and a presentation of the archival project with emphasis on the concept of cultural performance, concretized within performance studies paradigm using Philippine society and culture as context. The second part is a discussion of how data in the archive were documented and collected using focused ethnography as primary methodology. The method is argued to be the distinguishing mark of the project from other digital archives. Also, this section provides a detailed exposition about the significance of understanding local performance vocabularies and how these terms are translated into the archive through semantic framing. In the end, it is asserted that the Philippine Performance Archive on Cultural Performances functions not only as a repository of resource materials on the study of Philippine cultural performances but also as a performative cultural memory and a pedagogical tool.

Allanite is a common accessory mineral in igneous rocks that contains significant amounts of rare-earth elements (REEs), thorium (Th), and uranium (U). The presence of Th and U in the allanite exposes it to radiation resulting in radiation damage in its crystal structure and further leads to metamictization. Hence, allanite can be used as a natural analogue to assess the long-term radiation effects in materials for high-level nuclear waste disposal. It provides information on the effect of α-decay on the crystal structure including the stability and integrity of the material. In this study, the absorbed α-dose of allanite from Ombo, Palawan, Philippines, was estimated from the Th and U content and geological age of the mineral using X-ray fluorescence and gamma-ray spectrometry. The amount of Th and REE was measured to be around 1.37 and  30.4 wt.%, respectively. Radiometric dating using gamma-ray spectrometry estimated the age of the allanite mineral to be around 24–35 million years. Having obtained the amount of radioactivity and the time of exposure, the corresponding absorbed α-dose was estimated to be at 2.84 × 1014 α-decays/mg. Results suggest that the allanite mineral studied has not accumulated significant radiation damage to cause amorphization and still exhibit a crystalline structure. This study may provide data on the properties of allanite or silicate matrices as part of the ongoing studies on silicate minerals as natural analogues.

In this paper, vulnerability curves of key building types in the Philippines are developed and presented. Vulnerability curves, expressed as damage ratio versus Modified Mercalli Intensity (MMI) scale, for each building type are derived using computational, empirical, and/or heuristic methods. In the computational method, nonlinear static pushover of each building model was carried out and the capacity spectrum method was used to compute the fragility curves and then the vulnerability curves are derived from assumed damage ratios. Empirical vulnerability curves are derived using available data on damage to buildings compiled from field surveys and reports after past earthquakes. Heuristic vulnerability curves are derived by processing opinion of structural engineers in the Philippines on the possible damage to buildings when subjected to different earthquake intensities. For most building types made from reinforced concrete and steel, computational curves are recommended while for building types made of wood, masonry, and/or light materials, empirical or heuristic curves are recommended. The set of vulnerability curves proposed represents a coherent set of damage functions across structural types, construction material, number of floors, and age of construction.

Physically cross-linked hydroxyethyl cellulose (HEC) hydrogels of different concentrations are synthesized at room temperature, and the hydrogel films are evaluated for its antimicrobial and exudate absorption properties. Results showed that all the hydrogels inherently possess antimicrobial property for all the HEC concentrations tested. The maximum water uptake is determined to be 173.8% for the 13.75% HEC hydrogel. At the same HEC concentration, the hydrogel absorbed the largest amount of exudate. The rate of diffusion in the longitudinal direction is observed to be higher, but the exudate was observed to travel generally farther in the radial direction. The diffusion coefficient model reported by Kipcak, et al. in 2014 was observed to be valid and applicable for the HEC hydrogels. Lastly, scanning electron microscopy showed the microstructure of the fibers and pores of the hydrogels.

In this study, a self-adhesive hydrogel wound dressing was developed by combining hydroxyethyl cellulose (HEC) hydrogel with a tannic acid-polyethylene glycol (TAPE) adhesive bioadhesive with gelatin. Test samples of the cellulosic wound dressing were prepared with three (3) different mixing ratios of the crosslinking solution, three (3) different adhesive formulation, and two different hydrogel/adhesive contact area (flat, ridged). Adhesion performances of these samples on porcine skin were evaluated by performing a T-peel test. Analysis of the HEC/TAPE-gelatin interface showed that the HEC cross-linking agent formulation, adhesive thickness, and presence of surface ridges showed significant three-way interaction effects, and these parameters were modeled using orthogonal polynomials and optimized via response surface methodology (RSM). The adhesion on the HEC-TAPE-gelatin interface was also investigated further using scanning electron microscopy (SEM), where it had been observed that greater adhesion occurred with a decrease in cross-linking density, thinner adhesive layer, and the presence of ridges. Lastly, disk diffusion testing indicated greater antimicrobial activity (mean inhibition zone = 12 mm) against S. aureus and P. aeruginosa in contrast to commercial hydrogel dressings (mean inhibition zone = 7.5 mm), while MTT assay on human lymphocytes resulted to a 98% cell survival rate. Based on these results, it was concluded that it is feasible to use HEC hydrogel with TAPE-gelatin adhesive for manufacturing self-adhesive wound dressing products.

A novel self-adhesive wound dressing product was developed using a hydroxyethyl cellulose (HEC) hydrogel layered with a TAPE-gelatin bioadhesive. This wound dressing was then evaluated for its sorption properties through diffusion and swelling tests, and the parameters analyzed were hydrogel formulation, wound dressing thickness and adhesive layer thickness. Results showed that the wound dressing produced using 6% NaOH/5% thiourea in the crosslinking solution, with 2.5 mm hydrogel thickness, and 0.2 mm TAPE-gelatin thickness had the highest water absorbed. Lastly, analysis on swelling kinetics based on a previous study was conducted to determine the diffusion coefficients for the composite wound dressing.

Furfural is the product of the hydrolysis of pentosan-rich materials which can normally be found in biomass. Pentosans from coconut shell, coconut husk, pineapple bagasse, and water hyacinth,  which are available agricultural wastes in the country, were used in this study. The laboratory synthesis of furfural was done by acid-catalyzed hydrolysis. The acid hydrolyzes were carried out at 180°C using dilute (0.2 M) sulfuric acid for different hydrolysis times. Results show that the study was successful in synthesizing furfural from the four different agricultural residues used. Furthermore, it was found out that furfural yield increases as digestion time increases, but only up to a certain hydrolysis time, different for every raw material, for which the maximum average percent mass furfural yield can be obtained. After which, a decrease in mass yield will be noticed.

Primer containing a brief introduction to the language Inagta Alabat (ISO 639-3 dul), an alphabet chart, and a phrase list. 

This is one of the outputs for the project Documenting Alabat Agta, a nearly-extinct language of the Philippines headed by Louward Allen M. Zubiri (Mangyan Heritage Center, University of Hawai'i at Mānoa) and funded by the U.S. Embassy in the Philippines.

Compilers and editors: Louward Allen M. Zubiri, Amy Jugueta, Julieta Alpay, Vincent Christopher Santiago, Irvin Jen Imperial

Illustrations by: Ara Villena

Illustrated compilation of localized literature in Inagta Alabat (ISO 639-3 dul).

 

This is one of the outputs for the project Documenting Alabat Agta, a nearly-extinct language of the Philippines headed by Louward Allen M. Zubiri (Mangyan Heritage Center, University of Hawai'i at Mānoa) and funded by the U.S. Embassy in the Philippines.

Compilers and editors: Louward Allen M. Zubiri, Amy Jugueta, Julieta Alpay, Vincent Christopher Santiago, Irvin Jen Imperial

Illustrations by: Ara Villena

Agricultural wastes are readily available in farming communities and can be utilised for off-grid electrification as an alternative to diesel generators. This work evaluates for the first time the life cycle environmental sustainability of these small-scale systems in the context of Southeast Asia. Rice and coconut residues are considered for direct combustion and gasification, and livestock manure for anaerobic digestion. Overall, anaerobic digestion is the best option for 14 out of 18 impacts estimated through life cycle assessment. The results also suggest that gasification has up to 12 times lower impacts per kWh than combustion, except for resource depletion. Combustion and gasification have 85% to two times lower impacts than diesel generators, except for eutrophication, ecotoxicity and human toxicity. Depending on the feedstock, global warming potential of anaerobic digestion ranges from being 170% lower to 41% higher than that of the diesel generator. Overall, providing power from residual biomass in small agricultural communities would reduce environmental impacts significantly while improving waste management practices.

A heterojunction device was fabricated via oxidation of a thin film and spray pyrolysis. In this work, a copper oxide (CuO) film was grown via magnetron sputtering of Cu film deposited on pre-cut glass substrates and subsequent oxidation at 450 °C in air. A titanium dioxide (TiO2) film was deposited on the CuO film via spray pyrolysis of titanium (IV) isopropoxide precursor at 200 °C. X-ray diffraction analysis revealed the formation of monoclinic CuO film and tetragonal anatase TiO2 film. Scanning electron microscopy images showed agglomerated grains for both films with TiO2 grains larger than CuO grains. I-V characteristic of the CuO-TiO2 heterojunction film exhibited a rectifying behavior with a turn-on voltage of around 1.3 V and an ideality factor of around 1.96. The heterojunction revealed an open circuit voltage of around 0.59 V and a short circuit current of 0.3 mA under 100 mW/cm2 solar light irradiation.