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Maskin M.,Malaysian Nuclear Agency | Tom P.P.,Malaysian Nuclear Agency | Lanyau T.A.,Malaysian Nuclear Agency | Brayon F.C.M.,MOSTI Inc | And 4 more authors.
AIP Conference Proceedings | Year: 2014

As a consequence of the accident at the Fukushima Dai-ichi Nuclear Power Plant in Japan, the safety aspects of the one and only research reactor (31 years old) in Malaysia need be reviewed. Based on this decision, Malaysian Nuclear Agency in collaboration with Atomic Energy Licensing Board and Universiti Kebangsaan Malaysia develop a Level-1 Probability Safety Assessment on this research reactor. This work is aimed to evaluate the potential risks of incidents in RTP and at the same time to identify internal and external hazard that may cause any extreme initiating events. This report documents the methodology in developing a Level 1 PSA performed for the RTP as a complementary approach to deterministic safety analysis both in neutronics and thermal hydraulics. This Level-1 PSA work has been performed according to the procedures suggested in relevant IAEA publications and at the same time numbers of procedures has been developed as part of an Integrated Management System programme implemented in Nuclear Malaysia. © 2014 AIP Publishing LLC.

Versari A.,University of Bologna | Patrizi C.,University of Bologna | Parpinello G.P.,University of Bologna | Mattioli A.U.,University of Bologna | And 3 more authors.
Journal of Chemical Technology and Biotechnology | Year: 2016

BACKGROUND: Malolactic fermentation (MLF) is a critical step in modern winemaking and the co-inoculation of lactic acid bacteria with yeasts represents an emerging approach to improve the quality of wine. This study aims to evaluate the effect of inoculation timing on the chemical and sensory characteristics of two commercial Cabernet Franc wines: (i) a control wine in which MLF was inoculated after the completion of alcoholic fermentation (AF); and (ii) a co-inoculated wine where simultaneous alcoholic and malolactic fermentations occurred. RESULTS: Besides the expected full conversion of malic acid into lactic acid, the MLF with co-inoculum of yeast/bacteria at initial AF allowed for reduced fermentation times, i.e. faster winemaking process. Although important changes in the chemical parameters of wines were found, especially color intensity and volatile compounds, there was a trend on the sensory evaluation of wines with a greater perception of red and ripe fruits in the case of co-inoculation wine, while the control wine was dominated by notes of spice and herbs. The results of GC/MS analysis showed the largest differences for the 3-hydroxy-2-butanone (acetoin, the reduced form of diacetyl) and isoamyl alcohol concentrations, the former was 3.2 times higher under co-inoculum conditions, whereas the latter showed the opposite behavior. CONCLUSION: The co-inoculation protocol proposed is a valuable choice for innovative winemaking of Cabernet Franc wines, and results from a large-scale winemaking process are provided for the first time. © 2015 Society of Chemical Industry © 2016 Society of Chemical Industry.

Aziz N.A.,Universiti Sains Malaysia | Sipaut C.S.,Universiti Malaysia Sabah | Abdullah A.A.-A.,Universiti Sains Malaysia | Abdullah A.A.-A.,MOSTI Inc
Journal of Chemical Technology and Biotechnology | Year: 2012

BACKGROUND: The aim of this work is to enhance the production of terpolyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-4-hydroxybutyrate) (P(3HB-co-3HV-co-4HB)) produced by a locally isolated bacterium, Cupriavidus sp. USMAA2-4. The monomer composition was varied by supplementing different carbon precursors and by manipulating the culture condition through one-stage cultivation. The effect of C/N ratio and different concentrations of carbon source and precursors were investigated in order to produce higher content of this terpolyester. Although research on this biodegradable polyester is abundant, studies on terpolyester P(3HB-co-3HV-co-4HB) are still limited. RESULTS: Supplementation of oleic acid in accumulation medium increased the bacterial growth and polyhydroxyalkanoate (PHA) accumulation. It was also shown that medium consisting of assorted carbon precursors at C/N 20 gave relatively high dry cell weight and P(3HB-co-3HV-co-4HB) content. Various compositions of terpolyester were obtained when the concentration of oleic acid and 4HB precursors were manipulated. The combination of oleic acid with γ-butyrolactone and 1-pentanol was found to be the best combination to produce high PHA content (81 wt%). The composition of monomer in P(3HB-co-3HV-co-4HB) was produced in the range 8-13 mol% for 3HV and 9-24 mol% for 4HB, respectively. CONCLUSIONS: The production of P(3HB-co-3HV-co-4HB) in shake-flasks successfully produced 81 wt% of PHA content. This manipulated culture condition can be used at larger scale to provide modeling for the production of terpolyester in a bioreactor. © 2012 Society of Chemical Industry.

Sipaut C.S.,Universiti Malaysia Sabah | Murni S.,Universiti Malaysia Sabah | Saalah S.,Universiti Malaysia Sabah | Hoon T.C.,Universiti Sains Malaysia | And 3 more authors.
Cellular Polymers | Year: 2012

In this study, synthesized polyols from refined cooking oil, one of the ingredients in producing polyurethane (PU) foam, were investigated. The effects of reaction time, pH and type of solvents used on the properties of the polyols were characterized by using gas chromatography mass spectrometry (GC-MS), Fourier transform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC). Further studies were carried out by using the synthesized polyols in combination with other chemicals for PU foam formation. The characterizations of the PU foams were performed through chemical, morphological and thermal analyses. The results showed that the polyols were synthesized successfully from refined cooking oil by using epoxidation and the hydroxylation process. 50% of the unsaturated fatty acids in the refined cooking oil were converted to saturated fatty acids and hydroxyl compounds as the reaction time increased up to five hours. However, the chemical contents in the polyols did not show significant changes as the pH value increased from pH3 to pH7. Using different types of solvent in the process showed that the hydroxyl content of the polyols ranged between 57 to 69 mg KOH/ g, with M̄ w in the range of 15325 to 19320 g mol -1.The results also revealed that not all the synthesized polyols were suitable for PU foam formation. It is recommended in this study that the minimum hydroxyl content and molecular weight of the synthesized polyol required for PU foam formation is 69 mg KOH/ g and 19320 g mol -1 respectively. The properties of PU foam are highly dependent on the polyol and the water (blowing agent) content. © 2012 Smithers Rapra Technology.

Azira T.M.F.,MOSTI Inc | Nursolehah A.A.,Universiti Sains Malaysia | Norhayati Y.,Universiti Sains Malaysia | Majid M.I.A.,MOSTI Inc | And 2 more authors.
World Journal of Microbiology and Biotechnology | Year: 2011

A locally isolated Gram-negative bacterium, Cupriavidus sp. USMAA2-4 was found capable of producing terpolymer poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-4-hydroxybutyrate) [P(3HB-co-3HV-co-4HB)] using γ-butyrolactone or 1,4-butanediol with either valeric acid or 1-pentanol as the carbon source. The present of 3HB, 3HV and 4HB monomers were confirmed by gas chromatography (GC) and nuclear magnetic resonance (NMR) analysis. PHA concentration of 1.9 g/l was the highest value obtained using the combination of 1,4-butanediol and 1-pentanol through one-step cultivation process. PHA concentration obtained through two-step cultivation process was higher for all the combinations and the highest value achieved was 2.5 g/l using γ-butyrolactone and 1-pentanol as carbon source. Various molar fractions of 4HB and 3HV ranging from 6 to 14 mol% and 39 to 87 mol%, respectively were produced through two-step cultivation process by manipulating the concentration of γ-butyrolactone. As the culture aeration was reduced, the molar fraction of 3HV and 4HB increased from 40 to 67 mol% and 10 to 24 mol%, respectively while the dry cell weight and PHA content decreased. The terpolymer produced was characterized using gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The number-average molecular weight (Mn) and the melting temperature (Tm)) of the terpolymer were in the range of 177-484 kDa and 160-164°C, respectively. © 2011 Springer Science+Business Media B.V.

Ansari N.F.,Universiti Sains Malaysia | Amirul A.A.,Universiti Sains Malaysia | Amirul A.A.,MOSTI Inc
Applied Biochemistry and Biotechnology | Year: 2013

Polyhydroxyalkanoates (PHAs) are hydrophobic biodegradable thermoplastics that have received considerable attention in biomedical applications due to their biocompatibility, mechanical properties, and biodegradability. In this study, the degradation rate was regulated by optimizing the interaction of parameters that influence the enzymatic degradation of P(3HB) film using response surface methodology (RSM). The RSM model was experimentally validated yielding a maximum 21 % weight loss, which represents onefold increment in percentage weight loss in comparison with the conventional method. By using the optimized condition, the enzymatic degradation by an extracellular PHA depolymerase from Acidovorax sp. DP5 was studied at 37 C and pH 9.0 on different types of PHA films with various monomer compositions. Surface modification of scaffold was employed using enzymatic technique to create highly porous scaffold with a large surface to volume ratio, which makes them attractive as potential tissue scaffold in biomedical field. Scanning electron microscopy revealed that the surface of salt-leached films was more porous compared with the solvent-cast films, and hence, increased the degradation rate of salt-leached films. Apparently, enzymatic degradation behaviors of PHA films were determined by several factors such as monomer composition, crystallinity, molecular weight, porosity, and roughness of the surface. The hydrophilicity and water uptake of degraded salt-leached film of P(3HB-co-70%4HB) were enhanced by incorporating chitosan or alginate. Salt-leached technique followed by partial enzymatic degradation would enhance the cell attachment and suitable for biomedical as a scaffold. © 2013 Springer Science+Business Media New York.

Muzaiyanah A.R.,Universiti Sains Malaysia | Amirul A.A.,Universiti Sains Malaysia | Amirul A.A.,MOSTI Inc
Applied Biochemistry and Biotechnology | Year: 2013

In this study, the ability of Cupriavidus sp. USMAA2-4 to synthesize polyhydroxyalkanoates (PHA) containing 4-hydroxyvalerate monomer (4HV) was studied through one-stage cultivation using γ-valerolactone as the carbon precursor. The presence of 4HV monomer unit in the polymer was detected through gas chromatography analysis, proving the capability of this wild strain bacterium to produce poly(3-hydrxybutyrate-co-3-hydroxyvalerate-co-4- hydroxyvalerate) [P(3HB-co-3HV-co-4HV)] terpolymer. Existence of a 4HV monomer unit in the PHA produced was further confirmed through 13C and 1H NMR analysis. P(3HB-co-88 % 3HV-co-1 % 4HV) terpolymer with the highest PHA content of 63 wt% was obtained through combination of 0.14 wt% C of γ-valerolactone with 0.42 wt% C of oleic acid. Various compositions of P(3HB-co-3HV-co-4HV) terpolymer with 3HV and 4HV compositions ranging from 11 to 94 mol% and from 1 to 4 mol%, respectively, were acquired by manipulating γ-valerolactone and oleic acid concentrations. The molecular weight and the thermal and mechanical properties of four different compositions of terpolymers - P(3HB-co-91 % 3HV-co-1 % 4HV), P(3HB-co-55 % 3HV-co-2 % 4HV), P(3HB-co-27 % 3HV-co-2 % 4HV), and P(3HB-co-9 % 3HV-co-1 % 4HV) - were characterized. Among these terpolymers, P(3HB-co-27 % 3HV-co-2 % 4HV) terpolymer with a molecular weight of 5.7 (105 Da) exhibited the highest elongation to break (264 %). The monomer unit compositional distributions of these terpolymers were investigated through acetone-water fractionation analysis. The results suggested that these produced terpolymers had broad 3HV compositional distribution and narrow 4HV compositional distribution. © 2013 Springer Science+Business Media New York.

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