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201.
Raja Tahir Mahmood Muhammad Javaid Asad Nazia Mehboob Maria Mushtaq Muhammad Gulfraz Muhammad Asgher Nasir M. Minhas Saqib Hussain Hadri 《Applied biochemistry and biotechnology》2013,170(4):895-908
Fungi are considered good producers of industrially valuable enzymes with higher enzymatic activities. Among these cellulases are group of extracellular enzymes commonly employed in many industries for the hydrolysis of cellulolytic material. Aspergillus fumigatus produced exoglucanase having high enzymatic activity (83 U/gds) during the solid-state fermentation of wheat straw under optimum physical and nutritional conditions. Maximum production was obtained after 72 h of fermentation, at 55 °C temperature, pH 5.5, 80 % moisture level, and 2 mL fungal inoculum. Production was further increased by the addition of fructose (0.3 %) as additional carbon source, peptone (0.4 %) as nitrogen source, Tween-80 (0.3 %) as surfactant, and ammonium sulfate (0.2 %) in media. Exoglucanase was 2.30-folds purified by adding 40 % ammonium sulfate with volumetric activity 95.4 U/gds and specific activity 14.74 U/mg. Further, it was 5.18-folds purified by gel filtration chromatography with volumetric activity 115.2 U/gds and specific activity 33.10 U/mg. Purified exoglucanase has maximum activity at 55 °C and pH 4.8 using 1 % Avicel aqueous solution as substrate. The K m and V max were 4.34 mM and 7.29 μM/min, respectively. Calcium, magnesium, and zinc ions have positive effect on exoglucanase activity. 相似文献
202.
Ahmed Abed Nabil Bouazizi Stephane Giraud Ahmida El Achari Christine Campagne Olivier Thoumire Reddad El Moznine Omar Cherkaoui Julien Vieillard Abdelkrim Azzouz 《高分子科学》2020,(1):84-91,I0007
Polyester(PET) was pre-activated by atmospheric air plasma and coated by various inorganic oxide nanoparticles(MOx) such as titanium dioxide(TiO2), zinc oxide(ZnO), and silicon oxide(SiO2), using poly(vinylidene fluoride)(PVDF) and chitosan(CT) as binders. The resulting PET-PVDF-MOx-CT composites were thermally compressed and then characterized by scanning electron microscopy, Fourier infrared spectroscopy, thermal gravimetric analysis, and flame retardancy(FR) ability tests. PET modifications resulted in more thermally stable and less harmful composites with weaker hazardous gas release. This was explained in terms of structure compaction that blocks pyrolysis gas emissions.CT incorporation was found to reduce the material susceptibility to oxidation. This judicious procedure also allowed improving flame retardancy ability, by lengthening the combustion delay and slowing the flame propagation. Chitosan also turned out to contribute to a possible synergy with the other polymers present in the synthesized materials. These results provide valuable data that allow understanding the FR phenomena and envisaging low-cost high FR materials from biodegradable raw materials. 相似文献
203.
Razak Hussain Rolly Yadav Mushtaq Ahmed Tabreiz A. Khan Devesh Kumar Yusuf Akhter 《Journal of computational chemistry》2020,41(14):1330-1336
Tri11 (now renamed as tri22) encoded cytochrome P450 monooxygenase in Trichoderma brevicompactum catalyzes the C-4 C-H hydroxylation of 12, 13-epoxytrichothec-9-ene (EPT) to produce trichodermol in the biosynthetic pathway of trichodermin/harzianum A. The density functional theory (DFT)-quantum mechanics (QM) approach is applied to elucidate the hydroxylation of EPT by using a model active species of P450 (Cpd I). The QM calculations were performed on the active site complex, to find out transition-state structure, intermediate, and product complexes for the two spin states at different potential energy surfaces. The two state reactivity rebound-free product formation resulted from the interplay of two spin states (doublet and quartet). 相似文献
204.
Gil Otis Molhm Nassir Michael Zutta Abed Saady Prof. Sharon Ruthstein Prof. Yitzhak Mastai 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21110-21115
Many inorganic materials can form crystals, but little is known about their enantioselective crystallization. Herein, we report on the enantioselective crystallization of ϵ-Zn(OH)2 (Wulfingite) chiral crystals by using amino acids. Crystals of ϵ-Zn(OH)2 were crystallized from supersaturated sodium hydroxide and zinc nitrate aqueous solutions in the presence of l - or d -arginine. All of the chiral measurements, such as selective chiral adsorption by circular dichroism (CD), chiral chromatography, and polarimetry measurements, clearly show chiral discrimination during the crystallization of ϵ-Zn(OH)2. In addition, a new method has been developed for identifying chirality in crystals by using electron paramagnetic resonance (EPR). Although the values of chiral induction of the ϵ-Zn(OH)2 crystals obtained are somewhat low, these values are still significant because they demonstrate that enantioselectivity during the crystallization of chiral inorganic crystals with chiral additives can be achieved. The method can be applied to many chiral inorganic systems. Understanding and controlling the crystallization of chiral inorganic crystals is important for gaining knowledge on the interaction of chiral molecules with inorganic surfaces. This knowledge can lead to an understanding of basic scientific questions such as the evolution of homochirality in biomolecules and the development of chiral inorganic crystals for a variety of purposes such as asymmetric catalysis and optical applications. 相似文献
205.
Muhammad Mushtaq Isa M. Tan Lukman Ismail Susan Y. C. Lee M. Nadeem M. Sagir 《Journal of Dispersion Science and Technology》2014,35(3):322-328
The synthesis and cloud point behavior of high oleate ester-derived nonionic surfactants are now reported. The effect of various polyethoxylate chain lengths (polyethylene glycol with 7, 11, and 16 units of ethylene oxide (EO) monomer) as the surfactant's hydrophilic head on the cloud point was investigated. The effect of varying amounts of sodium chloride and five different ionic surfactants on the cloud points of the synthesized nonionic surfactants were also presented. When the chain length of polyethoxylate increased, the cloud point of the synthesized nonionic surfactant also increased, ranging from 16°C, 43°C, and 64°C for 7, 11, and 16 EO units, respectively. Increments in sodium chloride concentration depressed the cloud point values of the synthesized nonionic surfactants linearly. The addition of ionic surfactants elevated the cloud points of the synthesized nonionic surfactant. However, in the presence of sodium chloride, the cloud point of the mixed ionic-nonionic solution was suppressed and anincrease in ionic surfactant concentration was required to elevate the cloud point. It was also found that the cloud points of synthesized surfactants can be raised up to 95°C in the presence of 4wt% NaCl solution. 相似文献
206.
S. Abbas A. Mushtaq Q. M. Qazi 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):197-203
Technetium-99m and iodine-131 are the leading isotopes used in diagnosis and radiotherapy, respectively in Pakistani nuclear medical centers. Both radionuclides are regularly supplied by Isotope Production Division (IPD), PINSTECH to nuclear medical centers in Pakistan. The packages of 32P, 99Mo → 99mTc generators, and 131I, are prepared at IPD and dispatched by air, rail or road according to the desired activity at reference day to nuclear medical centers. An accurate determination of the activity to be administered to the patient plays key role on the quality of the clinical result of a medical investigation. Activity meters are employed for quantification of radioactivity of radionuclides at supplier site as well as by the users. In order to investigate the performance on the quality of activity measurements and elution efficiency of PAKGEN 99mTc generators, a pilot program of intercomparison was organized between the supplier and the users. The results of intercomparison of the activity measurements showed a maximum difference of ±13 % between supplier and nuclear medical centers. 相似文献
207.
Farid R. Zaggout Abed El Fattah A. Qaraman Hassan Abed El Aziz 《Journal of Dispersion Science and Technology》2013,34(1):58-62
This study considers the nature of interactions between the sol gel derived inorganic matrix and α‐naphtholphthalein pH‐indicator, the method is based on the physical entrapment of the indicator molecules in sol gel matrix, the immobilized α‐naphtholphthalein pH‐indicator shows similar behavior as its solution counterpart. The UV/VIS spectra indicate that the α‐naphtholphthalein retains its structure during the sol gel reactions in terms of response to pH. α‐Naphtholphthalein can be regarded as uniformly distributed in the sol gel matrix. This observation has been confirmed using polarized microscopy. 相似文献
208.
A. Mushtaq Masood Iqbal Atta Muhammad 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(3):379-392
Technetium-99m is the short-lived daughter product of the parent molybdenum-99, which is mainly produced by the fission of
uranium-235. Management of radioactive waste is an integral part of fission 99Mo production and has high priority during the planning, design, construction and operational phase of a molybdenum-99 production
facility. Within the licensing procedure the strategy of waste management, including the route for the spent targets and long
lived fission products has to be described and approved by the responsible authorities. Waste will be generated as solids,
liquids, and gases, and will include material in the low, intermediate and even highly radioactive categories. Initial treatment
of waste streams is usually required at the production site, prior to short or long term storage. This technology is established
and generally available in countries with an existing nuclear industry, such as Pakistan. In some instances storage facilities
may need to be constructed. On site, treatment of gaseous waste will be carried out in the production facility while off-site
treatment will be performed for solids and liquid radioactive waste. 相似文献
209.
Communicated by N.R. Reilly 相似文献
210.
Aromatic nitrations by tetranitromethane are shown to be photo-chemically initiated and are believed to proceed via trinitromethyl nitrite. 相似文献