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31.
A novel method for immobilization of Thermomyces lanuginosus lipase onto polyglutaraldehyde-activated poly(styrene-divinylbenzene) (STY-DVB), which is a hydrophobic microporous support has been successfully developed. The copolymer was prepared by the polymerization of the continuous phase of a high internal phase emulsion (polyHIPE). The concentrated emulsion consists of a mixture of styrene and divinylbenzene containing a suitable surfactant and an initiator as the continuous phase and water as the dispersed phase. Lipase from T. lanuginosus was immobilized covalently with 85% yield on the internal surface of the hydrophobic microporous poly(styrene-divinylbenzene) copolymer and used as a biocatalyst for the transesterification reaction. The immobilized enzyme has been fully active 30 days in storage and retained the activity during the 15 repeated batch reactions. The properties of free and immobilized lipase were studied. The effects of protein concentration, pH, temperature, and time on the immobilization, activity, and stability of the immobilized lipase were also studied. The newly synthesized microporous poly(styrene-divinylbenzene) copolymer constitutes excellent support for lipase. It given rise to high immobilization yield, retains enzymatic activity for 30 days, stable in structure and allows for the immobilization of large amount of protein (11.4mg/g support). Since immobilization is simple yet effective, the newly immobilized lipase could be used in several application including oil hydrolysis, production of modified oils, biodiesel synthesis, and removal of fatty acids from oils. 相似文献
32.
Jalarvo N Bordallo HN Aliouane N Adams MA Pieper J Argyriou DN 《The journal of physical chemistry. B》2008,112(3):703-709
Incoherent inelastic neutron scattering experiments were performed on Na0.7CoO2 and Na0.28CoO2.1.3H2O in order to understand how the dynamics of the hydrogen-bond network of water is modified in the triangular crystalline lattice NaxCoO2.yH2O. Using quasi-elastic neutron scattering (QENS), we were able to differentiate between two types of proton dynamics: a fast process (due to water strongly bound into the sodium cobalt oxyhydrate structure during the hydration process) and a slow process (likely attributable to a collective motion). High-resolution QENS experiments, carried out on Na0.28CoO2.1.3H2O, show that, at temperatures above 310 K, the water dynamics can be well-described by a random jump diffusion model characterized by a diffusion constant equal to 0.9 x 10(-9)m2/s, which is significantly lower than the rate of diffusion for bulk water. Furthermore, our results indicate that, at room temperature, the sodium ions have no influence on the rotational dynamics of the "fast" water molecules. 相似文献
33.
Hasan?Erdem??amurluEmail author ?mer?Kesmez Esin?Burunkaya Nadir?Kiraz Zerin?Ye?il Meltem?Asiltürk Ertu?rul?Arpa? 《Chemical Papers》2012,66(5):461-471
Self-cleaning photocatalytic TiO2 films are beneficial since they reduce the maintenance cost and enhance the efficiency of various optical systems, especially
thermal and photovoltaic solar systems. However, the presence of a TiO2 layer on glass reduces the transmission of incident light, which leads to a decrease in efficiency. This drawback can be
overcome by applying a layer of anti-reflective coating beneath the TiO2 layer. Generally, the anti-reflective layer is porous silica. The presence of the anti-reflective layer compensates for the
loss of light transmittance caused by the photocatalytic TiO2 top layer. This paper reviews some of the previous and the latest fundamental studies in the literature on anti-reflective,
self-cleaning and multi-functional films. 相似文献
34.
M. Salman Haider Godlisten Shao Ayyaz Ahmad S. Muhammad Imran Nadir Abbas Ghulam Abbas Manwar Hussain Hee Taik Kim 《Journal of Saudi Chemical Society》2019,23(7):828-835
This study demonstrates a novel, facile and one-pot approach to synthesize silica nanoparticles with silver at core and crust (SiNP-AgCC). A modified Stöber method was used to make SiNP-AgCC. A significant reduction in the size of SiO2 nanoparticles was seen, with 2–5 nm AgNPs being uniformly distributed on the surface and 10–20 nm AgNPs in the center. A typical mesoporous SiO2 particle (SiNP) produced using the Stöber method was transformed to nanoporous SiO2 by this modified Stöber method. Nanoporous SiO2 particles with silver in the center are advantageous for slow and consistent Ag+ release, which was confirmed by Ag+ ion release test. Antibacterial activities of the samples were tested to evaluate the disinfection performance of the samples on gram-negative bacteria (Escherichia coli) using disk diffusion and the LB-agar method. SiNP-AgCC showed prolonged silver release for more than 20 days and improved antibacterial properties even after five days of incubation. 相似文献
35.
The spin-1/2 quantum Heisenberg spin-glass system is studied in all spatial dimensions d by renormalization-group theory. Strongly asymmetric phase diagrams in temperature and antiferromagnetic bond probability p are obtained in dimensions d>or=3. The asymmetry at high temperatures approaching the pure ferromagnetic and antiferromagnetic systems disappears as d is increased. However, the asymmetry at low but finite temperatures remains in all dimensions, with the antiferromagnetic phase receding from the ferromagnetic phase. A finite-temperature second-order phase boundary directly between the ferromagnetic and antiferromagnetic phases occurs in d>or=6, resulting in a new multicritical point. In d=3, 4, 5, a paramagnetic phase reaching zero temperature intervenes asymmetrically between the ferromagnetic and reentrant antiferromagnetic phases. There is no spin-glass phase in any dimension. 相似文献
36.
Nadir Arada Eduardo Casas Fredi Tröltzsch 《Computational Optimization and Applications》2002,23(2):201-229
We study the numerical approximation of distributed nonlinear optimal control problems governed by semilinear elliptic partial differential equations with pointwise constraints on the control. Our main result are error estimates for optimal controls in the maximum norm. Characterization results are stated for optimal and discretized optimal control. Moreover, the uniform convergence of discretized controls to optimal controls is proven under natural assumptions. 相似文献
37.
M. Drewsen Ph. Laurent A. Nadir G. Santarelli A. Clairon Y. Castin D. Grison C. Salomon 《Applied physics. B, Lasers and optics》1994,59(3):283-298
We present an investigation of sub-Doppler effects in a cesium magneto-optical trap. First, a simple one-dimensional theoretical model of the trap is developed for aJ
g = 1 J
e = 2 transition. This model predicts the size of the trapped atom cloud and temperature as a function of laser intensity and detuning. In the limit of small magnetic field gradients, the trap temperature is found to be equal to the molasses temperature and a minimum size for the trap is calculated. We then describe several experiments performed in a three-dimensional cesium trap to measure the trap parameters, spring constant, friction coefficient, temperature and density. Whilst the temperature of the trapped atoms is found to be equal to the molasses temperature, in agreement with theory, the trap spring constant is found to be two orders of magnitude smaller than the one-dimensional prediction, a value close to that predicted by Doppler models. The maximum density is found to be on the order of 1012 atoms/cm3 or one atom per optical wavelength on average. When the number of trapped atoms becomes large, the temperature begins to increase dramatically. This excess temperature depends in a very simple way on the atom number, laser intensity and detuning, suggesting that its origin lies in multiple photon scattering within the trap. 相似文献
38.
Süheyla Özbey F. Betül Kaynak Mahmut Toŭrul Nadir Demirel Halil Hoşgören 《Journal of inclusion phenomena and macrocyclic chemistry》2003,45(1-2):123-128
A new complex of a chiral monoaza-crown ether, [R-(-)-2-ethyl-N-benzyl-4,7,10,13-tetraoxa-8,9-benzo-1-azacyclopentadec-8-ene...NaClO4], has been prepared and studied by x-ray diffraction. The compound crystallizes in space group P21 with cell dimensions a = 8.721(1), b = 16.318(2), c = 8.905(1) Å, = 100.80(1)°. The sodium cation is heptacoordinated and located significantly out of the best plane of the macrocycle ring. The donor atoms of the macrocycle are in the half-chair arrangement. 相似文献
39.
Mahmut Toğrul Nadir Demirel Betül Kaynak Süheyla Özbey Halil Hoşgören 《Journal of inclusion phenomena and macrocyclic chemistry》2004,50(3):165-171
The X-ray crystal structure of IX, perchlorate salt of R-(?-2-ethyl-N-benzyl-4,7,19,13-tetraoxa-8,9-benzo-1-azacyclopentadec-8-ene has been determined. In the molecule, the protonated nitrogen atom participates in two N-H?O hydrogen bonds. The unusually high proton affinity of aza crown ether leads to the formation of diastreomer instead of complex formation with chiral R-(+)-1-phenyl ethyl ammonium perchlorate and S-(?)-1-phenyl ethyl ammonium perchlorate. The complex ability of host ethers was evaluated in terms of structural modification. 相似文献
40.
Sepay Nayim Sepay Nadir Al Hoque Ashique Mondal Rina Halder Umesh Chandra Muddassir Mohd. 《Structural chemistry》2020,31(5):1831-1840
Structural Chemistry - Novel coronavirus, 2019-nCoV is a danger to the world and is spreading rapidly. Very little structural information about 2019-nCoV make this situation more difficult for drug... 相似文献