
@article {TAACA2020122980,
	title = {Spectroscopic studies of plasma-modified silver-exchanged zeolite and chitosan composites},
	journal = {Materials Chemistry and Physics},
	volume = {250},
	year = {2020},
	pages = {122980},
	abstract = {Composite biomaterials can be formed by combining natural or synthetic, organic or inorganic materials which are exactly or partially compatible when in contact with a living organism. To greatly improve the utilization of these biomaterials, understanding its interaction with its environment or host is essential. In this work, naturally-occurring and locally-abundant materials such as zeolite (Z) and chitosan (Ch), were fabricated as a silver-exchanged zeolite/chitosan (AgZ-Ch) composite using a solvent casting approach. The composites were subsequently exposed to argon (Ar) plasma excited by a 13.56~MHz radio frequency (RF) power source. Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) techniques were utilized to investigate the surface and subsurface properties of the AgZ-Ch composites. Results revealed different interactions within the bulk and on the surface of the composite. The interactions for the composite formation are dominated by the attraction of the AgZ species with the {\textendash}OH and {\textendash}NH2 functional groups of Ch. On the other hand, the surface composition of Ch was influenced by the etching effect of Ar with the {\textendash}COCH3 termination from the Ch. This study showed that the surface layer prefers to be terminated with amine and hydroxyl groups instead of amide functional groups. The present work also demonstrated the use of plasma irradiation to tune AgZ-Ch composite surface and tailor the reactivity of the functional groups on the surface.},
	keywords = {Chitosan, Plasma modification, Silver, Spectroscopy, Zeolite},
	issn = {0254-0584},
	doi = {https://doi.org/10.1016/j.matchemphys.2020.122980},
	url = {http://www.sciencedirect.com/science/article/pii/S0254058420303564},
	author = {Taaca, Kathrina Lois M. and Hideki Nakajima and Kanjana Thumanu and Pattanaphong Janphuang and Narong Chanlek and Magdaleno R. Vasquez}
}
@article {GARCIA2019102629,
	title = {Adsorption of diclofenac sodium in aqueous solution using plasma-activated natural zeolites},
	journal = {Results in Physics},
	volume = {15},
	year = {2019},
	pages = {102629},
	abstract = {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.},
	keywords = {Adsorption, Diclofenac, Plasma treatment, Zeolite},
	issn = {2211-3797},
	doi = {https://doi.org/10.1016/j.rinp.2019.102629},
	url = {http://www.sciencedirect.com/science/article/pii/S2211379719313312},
	author = {John Jomari M. Garcia and Julius Andrew P. Nu{\~n}ez and Hernando S. Salapare and Magdaleno R. Vasquez}
}
@article {Dahonog_2019,
	title = {Antibacterial Activity of Plasma-Treated Cu-Bentonite Nanocomposites},
	journal = {Journal of Physics: Conference Series},
	volume = {1191},
	year = {2019},
	month = {mar},
	pages = {012057},
	publisher = {IOP Publishing},
	abstract = {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.},
	doi = {10.1088/1742-6596/1191/1/012057},
	url = {https://doi.org/10.1088\%2F1742-6596\%2F1191\%2F1\%2F012057},
	author = {L A Dahonog and C B Tugado and E M Olegario-Sanchez and M R Vasquez}
}
@article {doi:10.1002/xrs.3029,
	title = {Determination of the REE content, geological age, and absorbed alpha dose of allanite mineral from Palawan, Philippines},
	journal = {X-Ray Spectrometry},
	volume = {48},
	number = {5},
	year = {2019},
	pages = {513-521},
	abstract = {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{\textendash}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~{\texttimes}~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.},
	doi = {10.1002/xrs.3029},
	url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/xrs.3029},
	author = {Dingle, Cheri Anne M. and Jecong, Julius Federico M. and Hila, Frederick C. and Ramo, Ma. Elina Salvacion V. and Guillermo, Neil Raymund D. and Vasquez Jr, Magdaleno R. and Samson, Vallerie Ann I.}
}
@article {MADERA2019102269,
	title = {Fabrication of oxidized CuO and spray-pyrolyzed TiO2 heterojunction thin film},
	journal = {Results in Physics},
	volume = {13},
	year = {2019},
	pages = {102269},
	abstract = {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 {\textdegree}C in air. A titanium dioxide (TiO2) film was deposited on the CuO film via spray pyrolysis of titanium (IV) isopropoxide precursor at 200 {\textdegree}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.},
	keywords = {Heterojunction, Oxidation, Photovoltaic, Spray pyrolysis, Thin films},
	issn = {2211-3797},
	doi = {https://doi.org/10.1016/j.rinp.2019.102269},
	url = {http://www.sciencedirect.com/science/article/pii/S2211379718328936},
	author = {Rozen Grace B. Madera and Melanie M. Martinez and Magdaleno R. Vasquez Jr.}
}
@article {taaca_olegario_vasquez_2019,
	title = {Impregnation of silver in zeolite{\textendash}chitosan composite: thermal stability and sterility study},
	journal = {Clay Minerals},
	volume = {54},
	number = {2},
	year = {2019},
	pages = {145{\textendash}151},
	publisher = {Cambridge University Press},
	doi = {10.1180/clm.2019.23},
	author = {Taaca, Kathrina Lois M. and Olegario, Eleanor M. and Magdaleno R. Vasquez}
}
@article {DELAVEGA2019573,
	title = {Plasma-functionalized exfoliated multilayered graphene as cement reinforcement},
	journal = {Composites Part B: Engineering},
	volume = {160},
	year = {2019},
	pages = {573 - 585},
	abstract = {A fast, facile, nonhazardous, environment-friendly, and high yield process was developed for the plasma treatment of graphite particles and the production of plasma-functionalized multilayered graphene (pf-MLG). Graphite particles (2585) with ,
	keywords = {Cement composite, Graphene exfoliation, Multilayered graphene, Nanoreinforcement, Plasma functionalization},
	issn = {1359-8368},
	doi = {https://doi.org/10.1016/j.compositesb.2018.12.055},
	url = {http://www.sciencedirect.com/science/article/pii/S1359836818327471},
	author = {Ma. Shanlene D.C. Dela Vega and Magdaleno R. Vasquez}
}
@article {Osonio2018,
	title = {Effects of discharge-forming gases on the antibacterial sensitivity of plasma-reduced silver impregnated in natural zeolites},
	journal = {Journal of Materials Science},
	volume = {53},
	number = {16},
	year = {2018},
	month = {Aug},
	pages = {11280{\textendash}11291},
	abstract = {The influence of plasma-forming gases such as argon and oxygen in the reduction of silver ions (\$\$\\backslashtext \Ag\\^+\$\$Ag+) infused into a natural zeolite framework has been investigated for antibacterial applications. Impregnation by soaking and ion exchange were combined with 13.56~MHz radio-frequency plasma to reduce \$\$\\backslashtext \Ag\\^+\$\$Ag+to their metallic state for a greener and energy-efficient process. The plasma treatment of the silver zeolite (AgZ) composites did not alter the crystalline structure of the zeolite, while successfully reducing \$\$\\backslashtext \Ag\\^+\$\$Ag+to its metallic form as a nanoparticle encapsulated by the zeolite. The antibacterial index of the AgZ composites against Staphylococcus aureus and Escherichia coli confirmed the fervent antibacterial activity of plasma-reduced Ag NP embedded in the zeolite matrix against the two bacterial strains. The highest activity belongs to the samples treated with oxygen plasma. This result is related to increased active area of contact and the incorporation of reactive oxygen species in the zeolite matrix, which contributed to the antibacterial sensitivity of the plasma-treated AgZ.},
	issn = {1573-4803},
	doi = {10.1007/s10853-018-2419-9},
	url = {https://doi.org/10.1007/s10853-018-2419-9},
	author = {Osonio, Airah P. and Magdaleno R. Vasquez}
}
@article {doi:10.1116/1.5030507,
	title = {Effects of RF plasma modification on the thermal and mechanical properties of electrospun chitosan/poly(vinyl alcohol) nanofiber mats},
	journal = {Journal of Vacuum Science \& Technology B},
	volume = {36},
	number = {4},
	year = {2018},
	pages = {04I101},
	doi = {10.1116/1.5030507},
	url = {https://doi.org/10.1116/1.5030507},
	author = {Latag,Glenn V. and Magdaleno R. Vasquez}
}
@article {Valerio_2018,
	title = {Grafting of acrylic acid onto microwave plasma-treated polytetrafluoroethylene (PTFE) substrates},
	journal = {Japanese Journal of Applied Physics},
	volume = {58},
	number = {SA},
	year = {2018},
	month = {nov},
	pages = {SAAC02},
	publisher = {Japan Society of Applied Physics},
	abstract = {Polytetrafluoroethylene (PTFE) has limited use in biomedical applications due to its poor wettability and low adhesion strength. Enhancing these properties through modification via plasma treatment coupled with grafting can further improve its surface properties ideal for biomedical applications. In this study, hydrophilic PTFE samples were successfully realized using a modified 2.45 GHz microwave oven as the plasma treatment device followed by grafting copolymerization using acrylic acid (AAc). This resulted to an increase in surface free energy (SFE) where samples subjected to air plasma treatment and AAc grafting exhibited the largest increase in SFE of 58 mJ m-2 compared to 17 mJ m-2 for the untreated samples. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy revealed new functional groups in the O1s and C1s regions of PTFE after plasma treatment and grafting. Atomic force microscopy analysis showed increase in surface roughness with the largest value of 67.7 nm found in air plasma-treated and grafted samples compared to 20.9 nm for the untreated PTFE sample. The plasma-treated and grafted PTFE surfaces did not exhibit hydrophobic recovery during a 7 d observation period as compared to plasma-treated samples only. The effective combination of plasma treatment and grafting process would broaden potential applications of PTFE as a biomaterial.},
	doi = {10.7567/1347-4065/aaec8b},
	url = {https://doi.org/10.7567\%2F1347-4065\%2Faaec8b},
	author = {John Kenneth C. Valerio and Hideki Nakajima and Magdaleno R. Vasquez}
}
@article {TAACA2018324,
	title = {Hemocompatibility and cytocompatibility of pristine and plasma-treated silver-zeolite-chitosan composites},
	journal = {Applied Surface Science},
	volume = {432},
	year = {2018},
	note = {20th International Vacuum Congress},
	pages = {324 - 331},
	abstract = {Silver-exchanged zeolite-chitosan (AgZ-Ch) composites with varying AgZ content were prepared by solvent casting and modified under argon (Ar) plasma excited by a 13.56MHz radio frequency (RF) power source. Silver (Ag) was successfully incorporated in a natural zeolite host without losing its antibacterial activity against Escherichia coli and Staphylococcus aureus. The AgZ particles were incorporated into a chitosan matrix without making significant changes in the matrix structure. The composites also exhibited antibacterial sensitivity due to the inclusion of AgZ. Plasma treatment enhanced the surface wettability of polar and nonpolar test liquids of the composites. The average increase in total surface free energy after treatment was around 49\% with the polar component having a significant change. Cytocompatibility tests showed at least 87\% cell viability for pristine and plasma-treated composites comparable with supplemented RPMI as positive control. Hemocompatibility tests revealed that pristine composites does not promote hemolysis and the blood clotting ability is less than 10min. Coupled with antibacterial property, the fabricated composites have promising biomedical applications.},
	keywords = {Chitosan, Composites, Plasma treatment, Silver, Zeolite},
	issn = {0169-4332},
	doi = {https://doi.org/10.1016/j.apsusc.2017.04.034},
	url = {http://www.sciencedirect.com/science/article/pii/S0169433217310516},
	author = {Taaca, Kathrina Lois M. and Magdaleno R. Vasquez}
}
@article {OSONIO2018156,
	title = {Plasma-assisted reduction of silver ions impregnated into a natural zeolite framework},
	journal = {Applied Surface Science},
	volume = {432},
	year = {2018},
	note = {20th International Vacuum Congress},
	pages = {156 - 162},
	abstract = {A green, dry, and energy-efficient method for the fabrication of silver-zeolite (AgZ) composite via 13.56MHz radio-frequency plasma reduction is demonstrated. Impregnation by soaking and ion-exchange deposition were performed to load the silver ions (Ag+) into the sodium-zeolite samples. Characterization was performed by optical emission spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and Brunauer{\textendash}Emmett{\textendash}Teller analyses. Results indicate the successful reduction of Ag+ to its metallic state on the surface of the zeolite with a mean diameter of 165nm. This plasma-induced reduction technique opens possibilities in several areas including catalysis, adsorption, water treatment, and medicine.},
	keywords = {Ag nanoparticles, Composites, Natural zeolite, Plasma reduction},
	issn = {0169-4332},
	doi = {https://doi.org/10.1016/j.apsusc.2017.09.076},
	url = {http://www.sciencedirect.com/science/article/pii/S0169433217327241},
	author = {Osonio, Airah P. and Magdaleno R. Vasquez}
}
@article {2096,
	title = {Antibacterial Activity of Copper-Loaded Plasma-Treated Natural Zeolites},
	journal = {Plasma Medicine},
	volume = {8},
	number = {1},
	year = {2018},
	pages = {1{\textendash}10},
	issn = {1947-5764},
	author = {Arantxa Danielle S. Montallana and Czerr Eljohn V. Cruz and Magdaleno R. Vasquez, Jr.}
}
@article {2095,
	title = {Antifouling Properties of Glass Substrates Irradiated with Acetylene Plasma},
	journal = {Plasma Medicine},
	volume = {8},
	number = {1},
	year = {2018},
	pages = {11{\textendash}22},
	issn = {1947-5764},
	author = {Meliton R. Chiong III and Ma. Cecilia M. Angub and Magdaleno R. Vasquez, Jr.}
}
@article {2091,
	title = {Radio-Frequency Plasma-Induced Biocompatibility of Polyimide Substrates},
	journal = {Plasma Medicine},
	volume = {8},
	number = {1},
	year = {2018},
	pages = {35{\textendash}44},
	issn = {1947-5764},
	author = {Magdaleno R. Vasquez Jr. and Prieto, Eloise I. and Wada, Motoi}
}
@article {doi:10.1063/1.5010480,
	title = {Antibacterial properties of Ag-exchanged Philippine natural zeolite-chitosan composites},
	journal = {AIP Conference Proceedings},
	volume = {1901},
	number = {1},
	year = {2017},
	pages = {030015},
	doi = {10.1063/1.5010480},
	url = {https://aip.scitation.org/doi/abs/10.1063/1.5010480},
	author = {Taaca, Kathrina Lois M. and Olegario, Eleanor M. and Magdaleno R. Vasquez}
}
@article {doi:10.1063/1.4995778,
	title = {The characteristics of DC laser photodetachment signals in a hot carbon cathode discharge},
	journal = {AIP Conference Proceedings},
	volume = {1869},
	number = {1},
	year = {2017},
	pages = {040002},
	doi = {10.1063/1.4995778},
	url = {https://aip.scitation.org/doi/abs/10.1063/1.4995778},
	author = {Masaki,S. and Hashiguchi,Y. and Vasquez,M. R. and Wada,M.}
}
@conference {de guzman2017,
	title = {Conductivity Improvement of Silver Nanowire Transparent Electrodes by Surface Plasma Treatment},
	booktitle = {Material Science and Engineering Technology V},
	series = {Materials Science Forum},
	volume = {890},
	year = {2017},
	month = {4},
	pages = {89{\textendash}92},
	publisher = {Trans Tech Publications Ltd},
	organization = {Trans Tech Publications Ltd},
	abstract = {High aspect ratio silver nanowires (Ag NWs) were successfully synthesized by CuCl2-mediated synthesis. Scanning electron microscopy (SEM) and X-Ray diffraction were employed to investigate the morphology and structure of the Ag products, respectively. Suspensions of Ag NW in ethanol were coated on glass substrates by Meyer rod coating to fabricate transparent conducting electrodes (TCE{\textquoteright}s). The electrodes were then plasma treated at a power of 75 W. The effects of increasing plasma treatment time and oxygen exposure on the sheet resistance of the transparent electrodes were investigated. A sheet resistance of 8 ${\O}mega$/sq with an optical transmittance of 80 \% at 550nm was obtained for an electrode with a nanowire density of 0.18 mg/cm2 after 5 mins of plasma (Ar) exposure.},
	keywords = {Plasma treatment, Silver Nanowires, Transparent Conducting Electrodes},
	doi = {10.4028/www.scientific.net/MSF.890.89},
	author = {De Guzman, Nathaniel and Lopez, Joybelle and Vasquez Jr., Magdaleno and Balela, Mary Donnabelle}
}
@article {Madera_2017,
	title = {Effects of RF plasma treatment on spray-pyrolyzed copper oxide films on silicon substrates},
	journal = {Japanese Journal of Applied Physics},
	volume = {57},
	number = {1S},
	year = {2017},
	month = {nov},
	pages = {01AB05},
	publisher = {Japan Society of Applied Physics},
	abstract = {The effects of radio-frequency (RF) argon (Ar) plasma treatment on the structural, morphological, electrical and compositional properties of the spray-pyrolyzed p-type copper oxide films on n-type (100) silicon (Si) substrates were investigated. The films were successfully synthesized using 0.3 M copper acetate monohydrate sprayed on precut Si substrates maintained at 350 {\textdegree}C. X-ray diffraction revealed cupric oxide (CuO) with a monoclinic structure. An apparent improvement in crystallinity was realized after Ar plasma treatment, attributed to the removal of residues contaminating the surface. Scanning electron microscope images showed agglomerated monoclinic grains and revealed a reduction in size upon plasma exposure induced by the sputtering effect. The current{\textendash}voltage characteristics of CuO/Si showed a rectifying behavior after Ar plasma exposure with an increase in turn-on voltage. Four-point probe measurements revealed a decrease in sheet resistance after plasma irradiation. Fourier transform infrared spectral analyses also showed O{\textendash}H and C{\textendash}O bands on the films. This work was able to produce CuO thin films via spray pyrolysis on Si substrates and enhancement in their properties by applying postdeposition Ar plasma treatment.},
	doi = {10.7567/jjap.57.01ab05},
	url = {https://doi.org/10.7567\%2Fjjap.57.01ab05},
	author = {Rozen Grace B. Madera and Melanie M. Martinez and Magdaleno R. Vasquez}
}
@article {TAACA2017383,
	title = {Fabrication of Ag-exchanged zeolite/chitosan composites and effects of plasma treatment},
	journal = {Microporous and Mesoporous Materials},
	volume = {241},
	year = {2017},
	pages = {383 - 391},
	abstract = {Composites made of zeolites with silver (Ag) and high molecular weight chitosan matrices were synthesized using a solvent-casting technique. XRD, ED-XRF, and FTIR results revealed the successful inclusion of Ag into the natural zeolite. Results also showed the possible redistribution of the exchangeable cations within the zeolite framework after the ion-exchange process. Plasma treatment modified the surface properties of the composites as revealed by AFM and surface free energy (SFE) calculations. Roughness increased with increasing Ag-zeolite content and increased further by at least 2.3 times after plasma exposure. Water contact angle decreased by half after treatment. SFE increased by at least 25\% due to the increased contribution of the polar component after plasma treatment. This work showed that the ion-exchange method is effective in incorporating Ag into the zeolite framework and plasma treatment can tune the surface properties such as roughness and wettability. With the promising properties of the composites attributed to the biocompatibility of chitosan and zeolite, the antibacterial activity of Ag and the improved surface characteristics due to plasma treatment, the material is a suitable candidate for biomedical applications.},
	keywords = {Chitosan, Clinoptilolite, Composites, Plasma treatment, Silver, Zeolite},
	issn = {1387-1811},
	doi = {https://doi.org/10.1016/j.micromeso.2017.01.002},
	url = {http://www.sciencedirect.com/science/article/pii/S1387181117300021},
	author = {Taaca, Kathrina Lois M. and Magdaleno R. Vasquez}
}
@article {Hubilla_2017,
	title = {Mechanical properties of epoxy composites with plasma-modified rice-husk-derived nanosilica},
	journal = {Japanese Journal of Applied Physics},
	volume = {57},
	number = {1S},
	year = {2017},
	month = {dec},
	pages = {01AG07},
	publisher = {Japan Society of Applied Physics},
	abstract = {In this study, we explored the use of rice-husk-derived nanosilica (nSiO2) as fillers in epoxy resins. The nSiO2 was irradiated with a capacitively coupled 13.56 MHz radio frequency (RF) plasma using an admixture of argon (Ar) and hexamethyldisiloxane (HMDSO) or 1,7-octadiene (OD) monomers. The plasma-polymerized nSiO2 was loaded at various concentrations (1{\textendash}5\%) into the epoxy matrix. Surface hydrophobicity of the plasma-treated nSiO2-filled composites increased, which is attributed to the attachment of functional groups from the monomer gases on the silica surface. Microhardness increased by at least 10\% upon the inclusion of plasma-modified nSiO2 compared with pristine nSiO2{\textendash}epoxy composites. Likewise, hardness increased with increasing loading volume, with the HMDSO-treated silica composite recording the highest increase. Elastic moduli of the composites also showed an increase of at least 14\% compared with untreated nSiO2-filled composites. This work demonstrated the use of rice husk, an agricultural waste, as a nSiO2 source for epoxy resin fillers.},
	doi = {10.7567/jjap.57.01ag07},
	url = {https://doi.org/10.7567\%2Fjjap.57.01ag07},
	author = {Fatima Athena D. Hubilla and Glenson R. Panghulan and Jason Pechardo and Magdaleno R. Vasquez}
}
@article {Sales_2017,
	title = {Properties of spray-deposited liquid-phase exfoliated graphene films},
	journal = {Japanese Journal of Applied Physics},
	volume = {57},
	number = {1S},
	year = {2017},
	month = {nov},
	pages = {01AF06},
	publisher = {Japan Society of Applied Physics},
	abstract = {In this study, we demonstrate the feasibility of spray-depositing exfoliated graphene on flexible polyimide (PI) and rigid (soda lime glass) substrates for optoelectronic applications. The water contact angles of the substrates increased by 13\% (for PI) and 49\% (for glass) when the surfaces are pretreated with hexamethyldisiloxane, which significantly improved the adhesion of the films. Raman spectral analyses confirmed a minimum of 15 and a maximum of 23 layers of exfoliated graphene deposited on the substrates. After deposition, the films were exposed to 13.56 MHz radio-frequency plasma containing an admixture of argon and nitrogen gases. Plasma treatment modified the electrical properties with a response analogous to that of a rectifier. A 39\% increase in transmittance in the visible region was also observed especially for glass substrates after plasma treatment without a significant change in film electrical conductivity.},
	doi = {10.7567/jjap.57.01af06},
	url = {https://doi.org/10.7567\%2Fjjap.57.01af06},
	author = {Maria Gabriela C. Sales and Ma. Shanlene D.C. Dela Vega and Magdaleno R. Vasquez}
}
@article {Cagomoc_2017,
	title = {RF plasma cleaning of silicon substrates with high-density polyethylene contamination},
	journal = {Japanese Journal of Applied Physics},
	volume = {57},
	number = {1S},
	year = {2017},
	month = {nov},
	pages = {01AB04},
	publisher = {Japan Society of Applied Physics},
	abstract = {Upon contact with a polymeric material, microparticles from the polymer may adhere to a silicon (Si) substrate during device processing. The adhesion contaminates the surface and, in turn, leads to defects in the fabricated Si-based microelectronic devices. In this study, Si substrates with artificially induced high-density polyethylene (HDPE) contamination was exposed to 13.56 MHz radio frequency (RF) plasma utilizing argon and oxygen gas admixtures at a power density of 5.6 W/cm2 and a working pressure of 110 Pa for up to 6 min of treatment. Optical microscopy studies revealed the removal of up to 74\% of the polymer contamination upon plasma exposure. Surface free energy (SFE) increased owing to the removal of contaminants as well as the formation of polar groups on the Si surface after plasma treatment. Atomic force microscopy scans showed a decrease in surface roughness from 12.25 nm for contaminated samples to 0.77 nm after plasma cleaning. The smoothening effect can be attributed to the removal of HDPE particles from the surface. In addition, scanning electron microscope images showed that there was a decrease in the amount of HDPE contaminants adhering onto the surface after plasma exposure.},
	doi = {10.7567/jjap.57.01ab04},
	url = {https://doi.org/10.7567\%2Fjjap.57.01ab04},
	author = {Charisse Marie D. Cagomoc and Mark Jeffry D. De Leon and Anna Sophia M. Ebuen and Marlo Nicole R. Gilos and Magdaleno R. Vasquez}
}
@conference {7882861,
	title = {Development of a Low Energy Carbon Molecular Ion Source},
	booktitle = {2016 21st International Conference on Ion Implantation Technology (IIT)},
	year = {2016},
	month = {Sep.},
	pages = {1-4},
	abstract = {Carbon molecular ions were extracted from an ion source operated with a carbon filament cathode. The mass spectrum of the extracted beam showed a higher current of diatomic carbon molecular ions than atomic carbon ions. The magnetic filter field successfully reduced extraction of smaller mass ions, to make molecular carbon ion current comparable to the ion current of helium, which was used as a discharge support gas.},
	keywords = {carbon, carbon filament cathode, diatomic carbon molecular ions, Discharges (electric), Fault location, ion implantation, ion sources, low energy carbon molecular ion source, Plasmas, thermionic cathodes},
	doi = {10.1109/IIT.2016.7882861},
	author = {S. Yamamoto and N. Miyamoto and T. Kasuya and Vasquez,M. R. and Wada,M.}
}
@article {Cagomoc_2016,
	title = {Enhanced chromium adsorption capacity via plasma modification of natural zeolites},
	journal = {Japanese Journal of Applied Physics},
	volume = {56},
	number = {1S},
	year = {2016},
	month = {nov},
	pages = {01AF02},
	publisher = {Japan Society of Applied Physics},
	abstract = {Natural zeolites such as mordenite are excellent adsorbents for heavy metals. To enhance the adsorption capacity of zeolite, sodium-exchanged samples were irradiated with 13.56 MHz capacitively coupled radio frequency (RF) argon gas discharge. Hexavalent chromium [Cr(VI)] was used as the test heavy metal. Pristine and plasma-treated zeolite samples were soaked in 50 mg/L Cr solution and the amount of adsorbed Cr(VI) on the zeolites was calculated at predetermined time intervals. Compared with untreated zeolite samples, initial Cr(VI) uptake was 70\% higher for plasma-treated zeolite granules (50 W 30 min) after 1 h of soaking. After 24 h, all plasma-treated zeolites showed increased Cr(VI) uptake. For a 2- to 4-month period, Cr(VI) uptake increased about 130\% compared with untreated zeolite granules. X-ray diffraction analyses between untreated and treated zeolite samples revealed no major difference in terms of its crystal structure. However, for plasma-treated samples, an increase in the number of surface defects was observed from scanning electron microscopy images. This increase in the number of surface defects induced by plasma exposure played a crucial role in increasing the number of active sorption sites on the zeolite surface.},
	doi = {10.7567/jjap.56.01af02},
	url = {https://doi.org/10.7567\%2Fjjap.56.01af02},
	author = {Charisse Marie D. Cagomoc and Magdaleno R. Vasquez}
}
@article {doi:10.1063/1.4934207,
	title = {Extraction characteristics of a low-energy ion beam system with a remote plasma chamber},
	journal = {Review of Scientific Instruments},
	volume = {87},
	number = {2},
	year = {2016},
	pages = {02B924},
	doi = {10.1063/1.4934207},
	url = {https://doi.org/10.1063/1.4934207},
	author = {Vasquez,M. R. and Wada,M.}
}
@article {doi:10.1063/1.4932988,
	title = {Low-energy ion beam-based deposition of gallium nitride},
	journal = {Review of Scientific Instruments},
	volume = {87},
	number = {2},
	year = {2016},
	pages = {02C103},
	doi = {10.1063/1.4932988},
	url = {https://doi.org/10.1063/1.4932988},
	author = {Vasquez,M. R. and Wada,M.}
}
@article {doi:10.1063/1.4832061,
	title = {Plasma characteristics of single- and dual-electrode ion source systems utilized in low-energy ion extraction},
	journal = {Review of Scientific Instruments},
	volume = {85},
	number = {2},
	year = {2014},
	pages = {02A717},
	doi = {10.1063/1.4832061},
	url = {https://doi.org/10.1063/1.4832061},
	author = {Vasquez,M. R. and Tokumura,S. and T. Kasuya and Wada,M.}
}
@article {doi:10.1063/1.4792820,
	title = {Metal negative ion production by an RF sputter self-extraction ion source},
	journal = {AIP Conference Proceedings},
	volume = {1515},
	number = {1},
	year = {2013},
	pages = {491-497},
	doi = {10.1063/1.4792820},
	url = {https://aip.scitation.org/doi/abs/10.1063/1.4792820},
	author = {Yamada,N. and T. Kasuya and Kenmotsu,T. and Vasquez Jr.,M. R. and Wada,M.}
}
@article {doi:10.1063/1.3292933,
	title = {Gallium ion extraction from a plasma sputter-type ion source},
	journal = {Review of Scientific Instruments},
	volume = {81},
	number = {2},
	year = {2010},
	pages = {02B717},
	doi = {10.1063/1.3292933},
	url = {https://doi.org/10.1063/1.3292933},
	author = {Vasquez,M. and Imakita,S. and T. Kasuya and Maeno,S. and Wada,M.}
}
@article {doi:10.1063/1.2816965,
	title = {Simulation studies on the evolution of gallium nitride on a liquid gallium surface under plasma bombardment},
	journal = {Review of Scientific Instruments},
	volume = {79},
	number = {2},
	year = {2008},
	pages = {02B910},
	doi = {10.1063/1.2816965},
	url = {https://aip.scitation.org/doi/abs/10.1063/1.2816965},
	author = {Vasquez,M. R. and Flauta,R. E. and Wada,M.}
}
@article {Flauta_2006,
	title = {Effect of Surface and Growth Conditions for Formation of Textured Polycrystalline GaN Crystals by Reactive N2Plasma},
	journal = {Japanese Journal of Applied Physics},
	volume = {45},
	number = {10B},
	year = {2006},
	month = {oct},
	pages = {8512{\textendash}8516},
	publisher = {Japan Society of Applied Physics},
	abstract = {The surface and growth conditions for the formation of textured polycrystalline bulk gallium nitride (GaN) crystals under nitrogen (N2) reactive plasma were investigated. Langmuir probe measurements were used to determine the electron density values near the Ga surface at different target locations and ranged from (6{\textendash}16){\texttimes}1010/cm2. Optical spectroscopy measurements showed reactive gallium (Ga) and nitrogen species present in the plasma. When the target was bombarded with highly energetic ions, peaks of sputtered Ga at 403 and 417 nm wavelengths were observed in the optical spectroscopy measurements. The top Ga surface showed increased roughening and the resulting crystals were of poor crystalline quality, with fresh Ga leftovers. Smoother crystals were formed when the Ga target was shielded from the direct bombardment of highly energetic N2 plasma, with no sputtered Ga peaks observed during the bombardment. X-ray diffraction (XRD) analysis results revealed well-oriented crystals at the (0002) reflection of GaN. This proved that the shielding of highly energetic ions to decrease roughening of the surface and allowing more neutrals for the reaction were effective in forming well-oriented bulk GaN crystals.},
	doi = {10.1143/jjap.45.8512},
	url = {https://doi.org/10.1143\%2Fjjap.45.8512},
	author = {Randolph E. Flauta and Magdaleno R. Vasquez and Henry J. Ramos and Wada, Motoi}
}
