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11.
In the present paper, the reaction of chemical immobilization of catalase on a crosslinked macromolecular carrier of a polysaccharide structure (gellan) is studied. The influence of some reaction parameters (enzyme/carrier, activator/carrier ratios, duration) on the activity of enzymatic products is analyzed. The kinetics of the biocatalytic process, stability under different pH and temperature conditions, and the inhibitors effect were studied for the immobilized enzymes. 相似文献
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Nicuşor Costea Andaluzia Matei 《Journal of Mathematical Analysis and Applications》2012,386(2):647-660
A frictional contact model, under the small deformations hypothesis, for static processes is considered. We model the behavior of the material by a constitutive law using the subdifferential of a proper, convex and lower semicontinuous function. The contact is described with a boundary condition involving Clarke?s generalized gradient. Our study focuses on the weak solvability of the model. Based on a fixed point theorem for set-valued mappings, we prove the existence of at least one weak solution. The uniqueness, the boundedness and the stability of the weak solution are also discussed; the investigation is based on arguments in the theory of variational–hemivariational inequalities. Finally, we present several examples of constitutive laws and friction laws for which our theoretical results are valid. 相似文献
14.
We study systematically the vibrational circular dichroism (VCD) spectra of the conformers of a simple chiral molecule, with one chiral carbon and an "achiral" alkyl substituent of varying length. The vibrational modes can be divided into a group involving the chiral center and its direct neighbors and the modes of the achiral substituent. Conformational changes that consist of rotations around the bond from the next-nearest neighbor to the following carbon, and bond rotations further in the chain, do not affect the modes around the chiral center. However, conformational changes within the chiral fragment have dramatic effects, often reversing the sign of the rotational strength. The equivalence of the effect of enantiomeric change of the atomic configuration and conformational change on the VCD sign (rotational strength) is studied. It is explained as an effect of atomic characteristics, such as the nuclear amplitudes in some vibrational modes as well as the atomic polar and axial tensors, being to a high degree determined by the local topology of the atomic configuration. They reflect the local physics of the electron motions that generate the chemical bonds rather than the overall shape of the molecule. 相似文献
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Mihaela Deaconu Ioana Nicu Robert Tincu Ana-Maria Brezoiu Raul-Augustin Mitran Eugeniu Vasile Cristian Matei Daniela Berger 《Chemical Papers》2018,72(8):1869-1880
Doxycycline, an antibiotic from the tetracycline class with a broad spectrum of activity, was used to prepare drug delivery systems based on pristine and functionalized mesostructured silica supports. MCM-41-type materials with different textural, structural, and surface properties were used to assess their influence on the drug release kinetics. Small- and wide-angle XRD, FTIR spectroscopy and N2 adsorption/desorption isotherms were used to characterize the carriers before and after doxycycline loading. The drug release experiments were performed in vitro in 0.2 M phosphate buffer solution at 37 °C, and the slowest drug release kinetics was obtained for magnesium-modified MCM-41 carrier. All drug-loaded materials exhibited good antibacterial activity against Klebsiella pneumoniae ATCC 10031 strain, similar to the drug alone. 相似文献
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For a resistance form ${(X, \mathcal{D}(\varepsilon),\varepsilon)}For a resistance form (X, D(e),e){(X, \mathcal{D}(\varepsilon),\varepsilon)} and a point x0 ? X{x_0 \in X} as boundary, on the space X0:=X \{x0}{X_0:=X {\setminus}\{x_0\}} we consider the Dirichlet space Dx0:={f ? D(e) | f(x0)=0}{\mathcal{D}_{x_0}:=\{f\in\mathcal{D}(\varepsilon)\, |\, f(x_0)=0\}} and we develop a good potential theory. For any finely open subset D of X
0 we consider a localized resistance form (DX0 \ D,eD{\mathcal{D}_{X_0 {\setminus} D},\varepsilon_{D}}) where DX0 \ D:={f ? Dx0 | f=0{\mathcal{D}_{X_0 {\setminus} D}:=\{f\in\mathcal{D}_{x_0}\, |\, f=0} on X0 \ D}, eD(f,g):=e(f,g){X_0 {\setminus} D\},\, \varepsilon_D(f,g):=\varepsilon(f,g)} for all f,g ? DX0 \ D{f,g\in\mathcal{D}_{X_0 {\setminus} D}}. The main result is the equivalence between the local property of the resistance form and the sheaf property for the excessive
elements on finely open sets. 相似文献
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In this paper we are concerned with the study of a class of quasilinear elliptic differential inclusions involving the anisotropic $\overrightarrow {p}(\cdot)$ -Laplace operator, on a bounded open subset of ${\mathbb R}^n$ which has a smooth boundary. The abstract framework required to study this kind of differential inclusions lies at the interface of three important branches in analysis: nonsmooth analysis, the variable exponent Lebesgue–Sobolev spaces theory and the anisotropic Sobolev spaces theory. Using the concept of nonsmooth critical point we are able to prove that our problem admits at least two non-trivial weak solutions. 相似文献
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Nicuşor Costea Andaluzia Matei 《Nonlinear Analysis: Theory, Methods & Applications》2010,72(9-10):3669-3680
We analyze the antiplane shear deformation of an elastic cylinder in frictional contact with a rigid foundation, for static processes, under the small deformation hypothesis. Based on the Knaster–Kuratowski–Mazurkiewicz technique in the theory of the hemivariational inequalities, we prove that the model has at least one weak solution. Moreover, we present several examples of constitutive laws and friction laws for which our theoretical results are valid. Finally, we comment on the conditions which guarantee the uniqueness of the solution. 相似文献
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Gabriel Marton Mark A. J. Koenis Hong-Bing Liu Carole A. Bewley Wybren Jan Buma Dr. Valentin Paul Nicu 《Angewandte Chemie (International ed. in English)》2023,62(38):e202307053
Determination of the absolute configuration of chiral molecules is a prerequisite for obtaining a fundamental understanding in any chirality-related field. The interaction with polarised light has proven to be a powerful means to determine this absolute configuration, but its application rests on the comparison between experimental and computed spectra for which the inherent uncertainty in conformational Boltzmann factors has proven to be extremely hard to tackle. Here we present a novel approach that overcomes this issue by combining a genetic algorithm that identifies the relevant conformers by accounting for the uncertainties in DFT relative energies, and a hierarchical clustering algorithm that analyses the trends in the spectra of the considered conformers and identifies on-the-fly when a given chiroptical technique is not able to make reliable predictions. The effectiveness of this approach is demonstrated by considering the challenging cases of papuamine and haliclonadiamine, two bis-indane natural products with eight chiral centres and considerable conformational heterogeneity that could not be assigned unambiguously with current approaches. 相似文献
20.
Suppose that U is the resolvent of a Borel right process on a Lusin space X. If is a U-excessive measure on X then we show by analytical methods that for every U-excessive measure with the Radon–Nikodym derivative d/d possesses a finely continuous version. (Fitzsimmons and Fitzsimmons and Getoor gave a probabilistic approach for this result.) We extend essentially a technique initiated by Mokobodzki and deepened by Feyel. The result allows us to establish a Revuz type formula involving the fine versions, and to study the Revuz correspondence between the -finite measures charging no set that is both -polar and -negligible (U being the potential component of ) and the strongly supermedian kernels on X. This is an analytic version of a result of Azéma, Fitzsimmons and Dellacherie, Maisonneuve and Meyer, in terms of additive functionals or homogeneous random measures. Finally we give an application to the context of the semi-Dirichlet forms, covering a recent result of Fitzsimmons. 相似文献