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41.
Nursolehah Abd Aziz Coswald Stephen Sipaut Amirul Al‐Ashraf Abdullah 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(11):1607-1614
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. Copyright © 2012 Society of Chemical Industry 相似文献
42.
The purpose of this research was to determine the effects of the packaging materials and size on the stability of monomeric anthocyanins, polyphenols, antioxidant activity, ascorbic acid, colour index and hydroxyl methyl furfural (HMF) during the 12‐month shelf life of sour cherry nectars at 4 °C and 20 °C. Sour cherry nectars were aseptically filled out into packaging of different sizes and materials. The packaging included cartons of two different sizes (200 and 1000 mL) and aluminium cans (330 mL). Results showed that the nectars were of better quality when stored at lower temperatures. HMF generally increased significantly for all nectars during storage. Conversely, the total polyphenol content and the antioxidant activity of the nectars stored in aluminium cans and the larger‐sized carton packaging decreased during storage. Lower anthocyanin loss and colour change were found in the nectars stored in aluminium cans. However, the better packaging material was found to be the large‐sized carton package when HMF was analysed. 相似文献
43.
In this study, the central composite design of the response surface methodology was employed to investigate the effects of reaction temperature, catalyst concentration and cross flow circulation velocity on the production of biodiesel in a TiO2/Al2O3 membrane reactor. High‐quality palm oil biodiesel was produced by combination of alkali transesterification and separation processes in the ceramic membrane reactor. The optimum conditions for the conversion of palm oil to biodiesel in the ceramic membrane reactor were as follows: 70°C reaction temperature, 1.12 wt% catalyst concentration and 0.211 cm s? 1 cross flow circulation velocity. The physical and chemical properties of the produced biodiesel were determined and compared with the standard specifications. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
44.
Song Pan Serdar Iplikci Kevin Warwick Tipu Z. Aziz 《Expert systems with applications》2012,39(12):10764-10771
Deep Brain Stimulation has been used in the study of and for treating Parkinson’s Disease (PD) tremor symptoms since the 1980s. In the research reported here we have carried out a comparative analysis to classify tremor onset based on intraoperative microelectrode recordings of a PD patient’s brain Local Field Potential (LFP) signals. In particular, we compared the performance of a Support Vector Machine (SVM) with two well known artificial neural network classifiers, namely a Multiple Layer Perceptron (MLP) and a Radial Basis Function Network (RBN). The results show that in this study, using specifically PD data, the SVM provided an overall better classification rate achieving an accuracy of 81% recognition. 相似文献
45.
A.K. Arof M.F. Aziz M.M. Noor M.A. Careem L.R.A.K. Bandara C.A. Thotawatthage W.N.S. Rupasinghe M.A.K.L. Dissanayake 《International Journal of Hydrogen Energy》2014
This paper reports the effect of using a mixed iodide salt system with two dissimilar cations to enhance the efficiency of dye-sensitized solar cells made with polyvinylidenefluoride (PVdF) based gel electrolyte. Instead of a single iodide salt, a mixture of potassium iodide (KI) with a small K+ cation and tetrapropylammonium iodide (Pr4NI) with a bulky Pr4N+ cation were used to provide the required iodide ion conductivity. Solar cells of configuration FTO/TiO2/Dye/electrolyte/Pt/FTO were fabricated using a mesoporous TiO2 electrode sensitized with a Ruthenium dye (N719). With identical electrolyte compositions, the cells with KI and Pr4NI alone gave efficiencies of 2.37% and 2.90% respectively. The cell with the mixed iodide system, KI:Pr4NI = 16.6:83.4 (% weight ratio), however, showed an enhanced efficiency of 3.92% with a short circuit current density of 9.16 mA cm−2, open circuit voltage of 674.4 mV and a fill factor of 63.4%. 相似文献
46.
S. Siavash Saei‐Dehkordi Aziz A. Fallah Mahbubeh Heidari‐Nasirabadi Mehran Moradi 《International Journal of Food Science & Technology》2012,47(8):1579-1585
This study aimed to determine the chemical composition, antimicrobial and antioxidative activity of Satureja khuzestanica Jamzad essential oil. The oil was analysed by GC and GC/MS. Twenty‐eight constituents were identified. The oxygenated monoterpenes (78.22%) were the principal compound group. Among them, carvacrol (53.86%) and thymol (19.84%) were the most abundant constituents. The oil exhibited an acceptable antimicrobial activity against most of the tested microorganisms. The checkerboard method was applied to determine fractional inhibitory concentration indices (FICIs) to interpret the synergetic, additive, indifference or antagonistic interactions between essential oil and each of antimicrobials (lysozyme, ciprofloxacin, fluconazole and amphotericin B) against food‐related microorganisms. The synergetic phenomenon (FICI ≤ 0.5) was observed in majority of combinations with the exception of the essential oil and lysozyme. The oil exhibited good 1,1‐diphenyl‐2‐picrylhydrazyl radical scavenging activity (IC50 = 28.71 μg mL?1). Also, the oil had strong antioxidative activity in β‐carotene‐linoleic acid assay relative antioxidant activity (RAA% = 95.45). This study demonstrated that the essential oil has beneficial biological properties and its simultaneous application with standard antimicrobials against food‐related microorganisms result in reduction in inhibitory doses of the antimicrobials in vitro. 相似文献
47.
Akram Shahrjerdi Saied Saeed Hosseiny Davarani Mostafa Mohammadpour Amini Ezzatollah Najafi Mohammad Janghouri Ezeddine Mohajerani Aziz Dehpour 《Journal of Materials Science》2014,49(1):441-449
A new lead complex, [Pb(mq)2], (mq = 2-methyl-8-hydroxyquinoline) was prepared via an electrochemical route from the oxidation of lead metal in the presence of 2-methyl-8-hydroxyquinoline in a fast and facile process. The complex was fully characterized by means of NMR and IR spectra and elemental analysis. The nanostructure of the prepared compound was obtained by sonoelectrochemical process and studied by scanning electron microscopy, atomic force microscopy, X-ray powder diffraction, IR spectroscopy and elemental analysis. Thermal stability of single crystalline and nanosize samples of the prepared compound was studied by thermal gravimetric and differential thermal analysis. The photoluminescence properties of the prepared compounds, as single crystals and as nanorods, have been investigated. The results showed a good correlation between the size and the shape of the complex particles and emission wavelength. The prepared complex was doped in PVK:PBD blend as guest and its application in the fabrication of OLED was studied. The ratio of lead complex was modified and was equal to 8 (w/w %) in PVK:PBD (100:40). 相似文献
48.
Mei-Ling Chong Nor' Aini Abdul Rahman Raha Abdul Rahim Suraini Abdul Aziz Yoshihito Shirai Mohd Ali Hassan 《International Journal of Hydrogen Energy》2009,34(17):7475-7482
Clostridium butyricum EB6 successfully produced hydrogen gas from palm oil mill effluent (POME). In this study, central composite design and response surface methodology were applied to determine the optimum conditions for hydrogen production (Pc) and maximum hydrogen production rate (Rmax) from POME. Experimental results showed that the pH, temperature and chemical oxygen demand (COD) of POME affected both the hydrogen production and production rate, both individually and interactively. The optimum conditions for hydrogen production (Pc) were pH 5.69, 36 °C, and 92 g COD/l; with an estimated Pc value of 306 ml H2/g carbohydrate. The optimum conditions for maximum hydrogen production rate (Rmax) were pH 6.52, 41 °C and 60 g COD/l; with an estimated Rmax value of 914 ml H2/h. An overlay study was performed to obtain an overall model optimization. The optimized conditions for the overall model were pH 6.05, 36 °C and 94 g COD/l. The hydrogen content in the biogas produced ranged from 60% to 75%. 相似文献
49.
The internationalization of construction companies is a subject of enduring interest among construction management scholars. The internationalization pattern of Malaysian contractors was explored, this time mainly using the international entrepreneurship body of literature as the theoretical basis. In doing so, the focus of the internationalization process was on the entrepreneurs or top management. Data were collected with a postal questionnaire survey and follow‐up semi‐structured interviews. The findings underscore the importance of the entrepreneurs’ decision in the surveyed firms’ internationalization trajectory. Top management’s perception of how their companies might benefit from internationalization was the highest ranked foreign market entry consideration. Top managements’ initial and subsequent motivation also fashioned their companies’ degree of internationalization and tactics for securing contracts. The characteristics of the entrepreneurs which drove their companies to internationalize were also captured. The international entrepreneurship domain continues to expand into previously uncharted areas. As such there is potential to uncover even more interesting findings from future research endeavours on international contractors using the international entrepreneurship approach. 相似文献
50.
Aziz Boutouil Hrimla Meryem Laamari My Rachid Elazhary Ilham Ben El Ayouchia H. El Haddad Mohammadine Anane Hafid Stiriba Salah-Eddine 《Protection of Metals and Physical Chemistry of Surfaces》2019,55(5):973-985
Protection of Metals and Physical Chemistry of Surfaces - The effect of an heterocycle triazole, namely (1-(4-methoxyphenyl)-1H-1,2,3-triazol-4-yl)methanol (MTM) on the corrosion of mild steel in... 相似文献