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21.
Ghislain Bare Aaron Diakiese Slim Zgoulli Ahmed Sabri Charles Gerday Philippe Thonart 《Applied biochemistry and biotechnology》1999,79(1-3):857-865
The thermoresistance of a cold-adapted subtilisin dried by spray-drying was studied. Proteolytic activity of this enzyme was
measured before and after spray-drying. Without chemical additives, spray-drying yields ranged from 2–13%. The use of arabic
gum and lactose in the composition of the enzyme solutions allowed the strengthening of the enzyme structures and increased
water mobility in the product. Increase of water mobility led to a shorter residence time of the product in the spray-drier
and a net yield increase was obtained (yield higher than 50%). The effect of two selective mutations on the thermoresistance
to spray-drying of the cold-adapted subtilisin was also investigated. Mutation T85D (introduction of an additional link with
an ion Ca2+ necessary for enzyme activity, by substitution of Asp for Thr 85) had no effect on the thermoresistance of the subtilisin
to spray-drying. Mutation H121W (introduction of an additional aromatic link by substitution of Trp for His 121) reduced the
drying yield from 66% (not modified subtilisin) to 52%. This higher thermosensitivity could be explained by an increase of
the hygroscopic character of the modified subtilisin (mutation H121W). 相似文献
22.
We define and study the Fock space associated with the spherical mean operator. Next, we establish some results for the Segal-Bergmann
transform for this space. Lastly, we prove some properties concerning Toeplitz operators on this space.
Received: May 11, 2007. Revised: May 20, 2008. Accepted: May 23, 2008. 相似文献
23.
We introduce the notion of an operating function on a subset of a F{\Phi} -algebra E. Then we use this notion to generalize results from Huijsmans and de Pagter (Proc. Lond. Math. Soc. 48:161–174, 1984) about
the connection between vector subspaces and subalgebras of E. In the second part we investigate the analogous problem for operators. 相似文献
24.
The notion of distribution function with respect to a conditional expectation is defined and studied in the framework of Riesz spaces. 相似文献
25.
Florin Diacu Slim Ibrahim Crystal Lind Shengyi Shen 《Communications in Mathematical Physics》2016,346(3):839-875
We obtain a natural extension of the Vlasov–Poisson system for stellar dynamics to spaces of constant Gaussian curvature \({\kappa \ne 0}\): the unit sphere \({\mathbb S^2}\), for \({\kappa > 0}\), and the unit hyperbolic sphere \({\mathbb H^2}\), for \({\kappa < 0}\). These equations can be easily generalized to higher dimensions. When the particles move on a geodesic, the system reduces to a 1-dimensional problem that is more singular than the classical analogue of the Vlasov–Poisson system. In the analysis of this reduced model, we study the well-posedness of the problem and derive Penrose-type conditions for linear stability around homogeneous solutions in the sense of Landau damping. 相似文献
26.
Mhand Hifi Slim Sadfi Abdelkader Sbihi 《Computational Optimization and Applications》2002,23(1):27-45
The Knapsack Sharing Problem (KSP) is an NP-Hard combinatorial optimization problem, admitted in numerous real world applications. In the KSP, we have a knapsack of capacity c and a set of n objects, namely N, where each object j, j = 1,...,n, is associated with a profit p
j and a weight w
j. The set of objects N is composed of m different classes of objects J
i, i = 1,...,m, and N =
m
i=1
J
i. The aim is to determine a subset of objects to be included in the knapsack that realizes a max-min value over all classes.In this article, we solve the KSP using an approximate solution method based upon tabu search. First, we describe a simple local search in which a depthparameter and a tabu list are used. Next, we enhance the algorithm by introducing some intensifying and diversifying strategies. The two versions of the algorithm yield satisfactory results within reasonable computational time. Extensive computational testing on problem instances taken from the literature shows the effectiveness of the proposed approach. 相似文献
27.
Walid Fakhfakh Slim Kaddeche Ali Abdennadher Daniel Henry Hamda Ben Hadid 《Comptes Rendus Mecanique》2006,334(5):332-339
A numerical study is conducted in order to determine the influence of a vertical magnetic field, the Reynolds number and a temperature stratification on the instabilities occurring in the Hartmann flow heated from below. For and , the results show that the vertical magnetic field has a stabilizing effect on both transverse oscillatory travelling waves and longitudinal stationary rolls . The temperature stratification is responsible of a destabilization of the transverse modes and the appearance of longitudinal modes non-existent for the isothermal Hartmann flow. Moreover, the extent of the domains of Re where the transverse modes prevail is found to narrow when Ha increases and to widen when Ra increases for a given value of Ha. On the other hand, for the modes, the extent of the domains of Re where they prevail increases when Ha grows. To cite this article: W. Fakhfakh et al., C. R. Mecanique 334 (2006). 相似文献
28.
Hatem Samaali Fehmi Najar Slim Choura Ali H. Nayfeh Mohamed Masmoudi 《Nonlinear dynamics》2011,63(4):719-734
In this paper, we propose the design of an ohmic contact RF microswitch with low voltage actuation, where the upper and lower
microplates are displaceable. We develop a mathematical model for the RF microswitch made up of two electrostatically actuated
microplates; each microplate is attached to the end of a microcantilever. We assume that the microbeams are flexible and that
the microplates are rigid. The electrostatic force applied between the two microplates is a nonlinear function of the displacements
and applied voltage. We formulate and solve the static and eigenvalue problems associated with the proposed microsystem. We
also examine the dynamic behavior of the microswitch by calculating the limit-cycle solutions. We discretize the equations
of motion by considering the first few dominant modes in the microsystem dynamics. We show that only two modes are sufficient
to accurately simulate the response of the microsystem under DC and harmonic AC voltages. We demonstrate that the resulting
static pull-in voltage and switching time are reduced by 30 and 45%, respectively, as compared to those of a single microbeam-microplate
RF-microswitch. Finally, we investigate the global stability of the microswitch using different excitation conditions. 相似文献
29.
Sandrine Morandat Slim Azouzi Estelle Beauvais Amira Mastouri Karim El Kirat 《Analytical and bioanalytical chemistry》2013,405(5):1445-1461
Supported lipid bilayers (SLBs) are biomimetic model systems that are now widely used to address the biophysical and biochemical properties of biological membranes. Two main methods are usually employed to form SLBs: the transfer of two successive monolayers by Langmuir–Blodgett or Langmuir–Schaefer techniques, and the fusion of preformed lipid vesicles. The transfer of lipid films on flat solid substrates offers the possibility to apply a wide range of surface analytical techniques that are very sensitive. Among them, atomic force microscopy (AFM) has opened new opportunities for determining the nanoscale organization of SLBs under physiological conditions. In this review, we first focus on the different protocols generally employed to prepare SLBs. Then, we describe AFM studies on the nanoscale lateral organization and mechanical properties of SLBs. Lastly, we survey recent developments in the AFM monitoring of bilayer alteration, remodeling, or digestion, by incubation with exogenous agents such as drugs, proteins, peptides, and nanoparticles. Figure
The experimental atomic force microscopy (AFM) setup used to examine supported lipid bilayers (SLBs) under physiological conditions. 相似文献
30.
Dr. Dominik Albat Dr. Slim Chiha Dr. Stephan Dohmen Pascal M. Engelhardt Dr. Hanna Sebode Dr. Arne Soicke Dr. Matthias Barone Dr. Matthias Müller Dr. Ronald Kühne Prof. Dr. Hans-Günther Schmalz 《European journal of organic chemistry》2023,26(39):e202300771
In the search for efficient inhibitors for the enabled/vasodilator-stimulated phosphoprotein homology 1 (EVH1) domain to reduce cell motility in metastatic cancer, we previously developed a toolkit of proline-derived modules (ProMs), which mimic the PPII helix found in the natural −FPPPP− binding motif of EVH1. In this work, we describe the modular assembly of these ProM-based pentapeptidic EVH1 ligands through liquid phase peptide synthesis. We initially used pentafluorophenyl (Pfp) active esters for amide bond formation and built up the growing peptide chain from the C- to the N-terminus. Switching to HATU/DIPEA coupling conditions and changing the directionality of the synthesis from the N- to the C-terminus afforded the target ligands with improved overall yields and purity. Employing a Fmoc-protected (instead of the N-acetylated) phenylalanine derivative as N-terminal building block significantly reduced epimerization. In contrast to the originally used solid phase peptide synthesis (SPPS), the developed solution phase method allowed for a facile alteration of the C-terminal ProM unit and the production of various pentapeptidic ligands in an efficient fashion even on a multigram scale. 相似文献