Philippine Nuclear Research Institute

Diliman Primero, Philippines

Philippine Nuclear Research Institute

Diliman Primero, Philippines

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Madrid J.F.,Philippine Nuclear Research Institute | Lopez G.E.P.,Philippine Nuclear Research Institute | Abad L.V.,Philippine Nuclear Research Institute
Radiation Physics and Chemistry | Year: 2017

The graft polymerization of glycidyl methacrylate onto electron beam pre-irradiated polypropylene (PP) nonwoven fabric was optimized using a 43 full factorial design analysis. The analysis yielded a polynomial equation that relates the linear, quadratic and interaction effects of the independent parameters to degree of grafting (Dg). The linear terms (i.e. absorbed dose, reaction time and monomer concentration), quadratic terms of time and concentration, and interaction term between absorbed dose and time were determined as significant independent parameters based from analysis of variance (ANOVA). The optimum grafting time and absorbed dose to achieve 150% Dg at 5% monomer concentration were 3.5 h and 39.8 kGy, respectively. The pristine PP, polypropylene-g-poly(glycidyl methacrylate) (PP-g-PGMA) and functionalized grafted materials were characterized using ATR-FTIR spectroscopy, thermogravimetric analysis and scanning electron microscopy. The affinities of the synthesized adsorbents towards the target metal ions at pH 4 were established to be in the following orderCr(VI) >> Pb(II) ~ Cd(II) for the amine functionalized PP-g-PGMA; and Pb(II) > Cd(II) > Cr(VI) for the carboxylic acid functionalized PP-g-PGMA. © 2017 Elsevier Ltd


Barba B.J.D.,Philippine Nuclear Research Institute | Tranquilan-Aranilla C.,Philippine Nuclear Research Institute | Abad L.V.,Philippine Nuclear Research Institute
Radiation Physics and Chemistry | Year: 2016

Various raw materials and hydrogels prepared from their combination were assessed for hemostatic capability using swine whole blood clotting analysis. Initial screening showed efficient coagulative properties from κ-carrageenan and its carboxymethylated form, and α-chitosan, even compared to commercial products like QuikClot Zeolite Powder. Blending natural and synthetic polymers formed into hydrogels using gamma radiation produced materials with improved properties. KC and CMKC hydrogels were found to have the lowest blood clotting index in granulated form and had the higher capacity for platelet adhesion in foamed form compared to GelFoam. Possible mechanisms involved in the evident thrombogenicity of the materials include adsorption of platelets and related proteins that aid in platelet activation (primary hemostasis), absorption of water to concentrate protein factors that control the coagulation cascade, contact activation by its negatively charged surface and the formation of gel-blood clots. © 2015 Elsevier Ltd.


Abad L.V.,Philippine Nuclear Research Institute | Relleve L.S.,Philippine Nuclear Research Institute | Racadio C.D.T.,Philippine Nuclear Research Institute | Aranilla C.T.,Philippine Nuclear Research Institute | De la Rosa A.M.,Philippine Nuclear Research Institute
Applied Radiation and Isotopes | Year: 2013

The antioxidant capacity of irradiated κ-, ι-, λ-carrageenans were investigated using the hydroxyl radical scavenging assay, reducing power assay and DPPH radical scavenging capacity assay. The degree of oxidative inhibition increased with increasing concentration and dose. The type of carrageenan had also an influence on its antioxidant activity which followed the order of lambda


Feliciano C.P.,Philippine Nuclear Research Institute | De Guzman Z.M.,Philippine Nuclear Research Institute | Tolentino L.M.M.,Philippine Nuclear Research Institute | Cobar M.L.C.,Philippine Nuclear Research Institute | Abrera G.B.,Philippine Nuclear Research Institute
Food Chemistry | Year: 2014

Usually in hospitals low-bacterial diets are served to immuno-compromised patients (ICPs). However, low-bacterial diets still pose a high risk of microbial infections and limit the food selection of the patients. Thus, pathogen-free dishes must be made available. This study presents the development of pathogen-free ready-to-eat (RTE) Filipino ethnic food chicken breast Adobo, sterilized by exposure to high-dose gamma rays (25 kGy) in combination with conventional treatments. Frozen vacuum-packed samples artificially inoculated with Escherichia coli, Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus and Salmonella enterica subsp. enterica serovar Typhimurium, were exposed to 25 kGy gamma radiation for complete sterilization. Microbial quality and sterility of the samples were analysed following 15, 30, and 60 days of storage at -4 °C. The effects of high-dose gamma irradiation on the nutritional quality and sensory characteristics of RTE chicken breast Adobo were also evaluated. © 2014 Elsevier Ltd. All rights reserved.


Obra G.B.,Philippine Nuclear Research Institute | Resilva S.S.,Philippine Nuclear Research Institute
Journal of Applied Entomology | Year: 2013

Enhancement of the sterile male performance in Bactrocera philippinensis through access to protein (yeast hydrolysate) and/or exposure to methyl eugenol (ME) was investigated in this study. The temporal occurrence of sexual maturity of B. philippinensis was determined for both laboratory sterile and wild flies. Laboratory tests were also conducted to determine the peak age of ME feeding in relation to male fly age and sexual maturity and effect of protein on the longevity of sterile males. Field cage mating tests were performed to examine the effect of adult diet (P+ vs. P-) and ME exposure (ME+ vs. ME-) on the mating competitiveness of the sterile male B. philippinensis. P+ME+ sterile male flies achieved significantly more matings with wild females than P+ME- or PE-ME- sterile males. Based on the relative sterile index, P+ sterile male flies were significantly more sexually competitive when competing for wild females than P- flies. The results confirm that the pre-release diet can be significantly improved to increase the effectiveness of the application of the sterile technique against B. philippinensis. © 2011 Blackwell Verlag, GmbH.


Madrid J.F.,Philippine Nuclear Research Institute | Ueki Y.,Japan Atomic Energy Agency | Seko N.,Japan Atomic Energy Agency
Radiation Physics and Chemistry | Year: 2013

A metal ion adsorbent was developed from a nonwoven fabric trunk material composed of both natural and synthetic polymers. A pre-irradiation technique was used for emulsion grafting of glycidyl methacrylate (GMA) onto an electron beam irradiated abaca/polyester nonwoven fabric (APNWF). The dependence of degree of grafting (Dg), calculated from the weight of APNWF before and after grafting, on absorbed dose, reaction time and monomer concentration were evaluated. After 50kGy irradiation with 2MeV electron beam and subsequent 3h reaction with an emulsion consisting of 5% GMA and 0.5% polyoxyethylene sorbitan monolaurate (Tween 20) surfactant in deionized water at 40°C, a grafted APNWF with a Dg greater than 150% was obtained. The GMA-grafted APNWF was further modified by reaction with ethylenediamine (EDA) in isopropyl alcohol at 60°C to introduce amine functional groups. After a 3h reaction with 50% EDA, an amine group density of 2.7mmole/gram adsorbent was achieved based from elemental analysis. Batch adsorption experiments were performed using Cu2+ and Ni2+ ions in aqueous solutions with initial pH of 5 at 30°C. Results show that the adsorption capacity of the grafted adsorbent for Cu2+ is four times higher than Ni2+ ions. © 2013 Elsevier Ltd.


Madrid J.F.,Philippine Nuclear Research Institute | Madrid J.F.,University of the Philippines at Diliman | Nuesca G.M.,University of the Philippines at Diliman | Abad L.V.,Philippine Nuclear Research Institute
Radiation Physics and Chemistry | Year: 2013

Water hyacinth fibers (Eichhornia crassipes) were functionalized using radiation-induced graft polymerization of glycidyl methacrylate by γ-rays from 60Co source. The simultaneous grafting technique was employed wherein the water hyacinth fibers were irradiated in nitrogen atmosphere in the presence of glycidyl methacrylate dissolved in water/methanol solvent. The effects of different grafting parameters to the grafting yield were evaluated. The optimal values of solvent, absorbed dose, dose rate, and concentration of monomer were found to be 1:3 (volume/volume) water-methanol solvent, 10kGy, 8kGyh-1 dose rate and 5% volume/volume glycidyl methacrylate, respectively. Using the optimum conditions, degree of grafting of approximately 58% was achieved. The grafted water hyacinth fibers were characterized using Attenuated Total Reflectance-Fourier Transformed Infrared Spectroscopy (ATR-FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDX). The results of these tests confirmed the successful grafting of glycidyl methacrylate onto water hyacinth fibers. © 2012 Elsevier Ltd.


Tranquilan-Aranilla C.,Philippine Nuclear Research Institute | Nagasawa N.,Japan Atomic Energy Agency | Bayquen A.,University of the Philippines at Manila | Dela Rosa A.,Philippine Nuclear Research Institute
Carbohydrate Polymers | Year: 2012

Carboxymethyl derivatives of kappa-carrageenan (KC) with varying degrees of substitution were obtained by multi-step carboxymethylation process. The structural and chemical profiles of the derivatives were determined by FT-IR, 13C NMR, gel permeation chromatography (GPC), elemental analysis, potentiometric titration and visual estimation of gelation temperature. The derivatives exhibited high degrees of substitution (DS) and acidity. However, sulfur content, molecular weight (Mw) and gelation temperature were lower compared to the parent KC polymer. FT-IR confirmed the presence of carboxymethyl (CM) groups in the polymer backbone while 13C NMR revealed that functionalization occurred at the three hydroxyl groups in kappa-carrageenan disaccharide unit. © 2011 Elsevier Ltd. All rights reserved.


Madrid J.F.,Philippine Nuclear Research Institute | Abad L.V.,Philippine Nuclear Research Institute
Radiation Physics and Chemistry | Year: 2015

Modified microcrystalline cellulose (MCC) was prepared through gamma radiation-induced graft polymerization of glycidyl methacrylate (GMA). Simultaneous grafting was employed wherein MCC with GMA in methanol was irradiated with gamma radiation in nitrogen atmosphere. The effects of different experimental factors such as monomer concentration, type of solvent and absorbed dose on the degree of grafting, Dg, were studied. The amount of grafted GMA, expressed as Dg, was determined gravimetrically. Information from grafted samples subjected to Fourier transformed infrared spectroscopy (FTIR) in attenuated total reflectance (ATR) mode showed peaks corresponding to GMA which indicates successful grafting. The X-ray diffraction (XRD) analysis revealed that the crystalline region of MCC was not adversely affected after grafting with GMA. The thermogravimetric analysis (TGA) data showed that the decomposition of grafted MCC occurred at higher temperature compared to the base MCC polymer. © 2015 Elsevier Ltd.


Abad L.V.,Philippine Nuclear Research Institute | Aranilla C.T.,Philippine Nuclear Research Institute | Relleve L.S.,Philippine Nuclear Research Institute | Dela Rosa A.M.,Philippine Nuclear Research Institute
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2014

The Philippines supplies almost half of the world's processed carrageenan as ingredient for different applications. In order to maintain the country's competitive advantage, R&D on radiation processed carrageenan with various potential applications had been undertaken. PVP-carrageenan hydrogels for wound dressing had been developed. A carrageenan-based radiation dose indicator can detect radiation dose of as low as 5 kGy. Irradiated carrageenan has also been tested as plant growth promoter. Irradiated carrageenans have been found have been found to contain some antioxidant properties which increase with increasing dose and concentration. Carboxymethyl carrageenans had also been developed that shows promising effect as super water absorbent for soil conditioner in plants. © 2014 Elsevier Ltd. All rights reserved.

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