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81.
Mostafa Hosseini Ali Asghar Karkhane Bagher Yakhchali Mehdi Shamsara Saeed Aminzadeh Dena Morshedi Kamahldin Haghbeen Ibrahim Torktaz Esmat Karimi Zahra Safari 《Applied biochemistry and biotechnology》2013,169(3):773-785
Lipases are one of the highest value commercial enzymes as they have broad applications in detergent, food, pharmaceutical, and dairy industries. To provide chimeric Bacillus thermocatenulatus lipase (BTL2), the completely conserved pentapeptide (112Ala-His-Ser-Gln-Gly116) was replaced with similar sequences (207Gly-Glu-Ser-Ala-Gly211) of Candida rugosa lipase (CLR) at the nucleophilic elbow region. For this purpose, three mutations including A112G, H113E, and Q115A were inserted in the conserved pentapeptide sequence of btl2 gene. Based on the crystal structures of 2W22, the best structure of opened form of the chimeric lipases were garnered using the MODELLER v9.10 software. The native and chimeric lipases were docked to a set of ligands, and a trial version of Molegro Virtual Docker (MVD) software was used to obtain the energy values. Docking results confirmed chimeric lipase to be better than the native lipase. Following the in silico study, cloning experiments were conducted and expression of native and chimeric btl2 gene in Pichia pastoris was performed. The native and chimeric lipases were purified, and the effect of these mutations on characteristics of chimeric lipase studied and then compared with those of native lipase. Chimeric lipase exhibited 1.6-fold higher activity than the native lipase at 55 °C. The highest percentage of both lipases activity was observed at 60 °C and pH of 8.0. The ion Ca2+ slightly inhibited the activity of both lipases, whereas the organic solvent enhanced the lipase stability of chimeric lipase as compared with the native lipase. According to the results, the presence of two glycine residues at the conserved pentapeptide region of this chimeric lipase (112 Gly-Glu-Ser-Ala-Gly 116) may increase the flexibility of the nucleophilic elbow region and affect the enzyme activity level. 相似文献
82.
M. Rajabi A. R. Ghassami M. Abbasi Firouzjah S. I. Hosseini B. Shokri 《Plasma Chemistry and Plasma Processing》2013,33(4):817-826
Polymer light-emitting devices were fabricated utilizing plasma polymerized thin films as emissive layers. These conjugated polymer films were prepared by RF plasma enhanced chemical vapor deposition using naphthalene as monomer. The effect of different applied powers on the chemical structure and optical properties of the conjugated polymers was investigated. Fourier transform infrared (FTIR) and Raman spectroscopies confirmed that a conjugated polymer film with a 3-D cross-linked network was developed. By increasing the power, products tended to form as highly cross-linked polymer films. The fabricated devices showed broadband Electroluminescence (EL) emission peaks with center at 535–550 nm. Photoluminescence (PL) spectra of plasma polymers showed different excimeric emissions, resulted from crosslinked architecture. As the plasma power increased, the optical properties showed two different domains; up to 200 W, EL, PL and UV–Vis spectra red-shifted and broadened significantly. At higher powers, a reverse behavior was observed. Also, the relation between the film structure and plasma species was investigated using optical emission spectroscopy. 相似文献
83.
Mohammad S. Hosseini Ali R. Rzaei Sarab 《International journal of environmental analytical chemistry》2013,93(5):375-385
Twenty-five uncultivated surface soil samples collected from the northern and southern regions of Dhaka Export Processing Zone (DEPZ), industrial area of Bangladesh, were analyzed for their contents of Y, lanthanides and natural radionuclides (Th and U) using an inductively coupled plasma mass spectrometer (ICP-MS). Analogous concentrations of the Y, lanthanides, Th and U were observed in the both regions of DEPZ around several kilometer distances. Further, the measured values showed no particular contamination. However, the concentrations of the light lanthanides (La, Ce and Nd) in the Bangladeshi soils were around twice the worldwide average value. But, the smooth curve of the chondrite normalized patterns of the lanthanides suggested that the lanthanide contents of the Bangladeshi soils in this area are the results of the natural dispersion process rather than anthropogenic activities. In addition, the relatively high Th and U concentrations and Th/U ratio were observed in Bangladeshi soils of this area, most likely due to the effect of their parent materials such as clay stones which have a high Th/U ratio. Since this is the first precise result for the Y, lanthanides, Th and U contents in Bangladeshi soils, it could be useful in understanding the background level and the characteristics of these elements in Bangladeshi soils. 相似文献
84.
Mohammad S. Hosseini Reyhaneh Hassan-Abadi 《International journal of environmental analytical chemistry》2013,93(3):199-207
Abstract The application of macro- and micro-electrodes constructed using the new ionophore were tested in a range of solution compositions reflecting concentrations found in fresh waters, and containing Cl?, NO3 ?, SO4 2-, HCO3 2-, H4SiO4 and a natural humic acid. The inhibition of the electrode responses to these ions was quantified using a mixed-solution method by optimising the agreement between the measured potentials and predictions from the Nicolsky-Eisenman equation. In addition, measurements were made in separate solutions of KC1 to enable results to be compared with the literature. Apart from the results obtained for humic acid, mean selectivity coefficients for 16 macro- and 21 micro-electrode experiments are given. The results indicate inhibition of the electrode response to phosphate for all the anions in the concentration ranges of 0.05–1 mM Cl?, 0.1–1.0 mM NO3 ?, 0.1–10.0 mM HCO3 ? and 0.1–1.5 mM SO4 2- with high selectivity for HPO4 2- in the presence of both dissolved silicon and a standard humic acid. This means that the application of the electrodes to hard waters is impracticable although studies of soft waters and laboratory studies in controlled conditions, e.g. calcium phosphate precipitation experiments, are feasible. 相似文献
85.
Farnoush Mousavizadeh Seyed Yahya Shirazi Beheshtiha Reyhaneh Rahnamafar 《合成通讯》2014,44(10):1483-1491
A facile protocol for the one-pot, multicomponent reaction of indole, 4-hydroxycoumarin, and aromatic aldehydes was developed using copper octoate as an inexpensive, commercially available, and efficient catalyst. This highly selective reaction eliminates the formation of homodimeric by-products (bisindoles and biscoumarins) and selectively results in the formation of heterodimeric adducts containing both indole and coumarin heterocycles. 相似文献
86.
Mohammad-Ali Ahmadi Seyed Reza Shadizadeh 《Journal of Dispersion Science and Technology》2014,35(11):1537-1542
More than 50% of oil is trapped in petroleum reservoirs after applying primary and secondary recovery methods for removal. Thus, to produce more crude oils from these reservoirs, different enhanced oil recovery (EOR) approaches should be performed. In this research, the effect of hydrophilic nanoparticles of SiO2 at 12 nm size, in (EOR) from carbonate reservoir is systematically investigated. Using this nanoparticle, we can increase viscosity of the injection fluid and then lower the mobility ratio between oil and nanofluid in carbonate reservoirs. To this end, a core flooding apparatus was used to determine the effectiveness and robustness of nanosilica for EOR from carbonate reservoirs. These experiments are applied on the reservoir carbonate core samples, which are saturated with brine and oil that was injected with nanoparticles of SiO2 at various concentrations. The output results depict that, with increasing nanoparticle concentration, the viscosity of the injection fluid increases and results in decreased mobility ratio between oil and nanofluid. The results confirm that using the nanoparticle increases the recovery. Also, increasing the nanoparticle concentration up to 0.6% increases the ultimate recovery (%OOIP), but a further increase to 1.0 does not have a significant effect. 相似文献
87.
88.
Sharifkhani Samira M. Yaftian Mohammad Reza Hosseini Majid Haji Zolfonoun Ehsan 《Journal of Analytical Chemistry》2022,77(4):505-512
Journal of Analytical Chemistry - In this study, for the first time, the organic gas steam-liquid extraction by a special hand-made cell was used as a simple and inexpensive preconcentration... 相似文献
89.
Salek Farhad Babaie Meisam Ghodsi Ali Hosseini Seyed Vahid Zare Ali 《Journal of Thermal Analysis and Calorimetry》2021,145(3):817-828
Journal of Thermal Analysis and Calorimetry - Number of hybrid vehicles has increased around the world significantly. Automotive industry is utilizing the hybridization of the powertrain system to... 相似文献
90.