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951.
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Inside Back Cover: Emergence of Uranium as a Distinct Metal Center for Building Intrinsic X‐ray Scintillators (Angew. Chem. Int. Ed. 26/2018) 下载免费PDF全文
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Laura Isac Gerold Thoelking Albrecht Schwab Hans Oberleithner Christoph Riethmuller 《Analytical and bioanalytical chemistry》2011,399(7):2351-2358
A demanding task of medicine is to understand and control the immune system. Central players in the cellular immune response
are the leukocytes that leave the blood stream for host defense. Endothelial cells limit the emigration rate of leukocytes.
Being located between blood and tissues, they permit or deny the passage. The exact mechanism of this process called diapedesis
is not solved yet. Leukocytes can principally traverse either between cells (paracellularly) or directly through an individual
endothelial cell (transcellularly). The transcellular way has recently gained experimental support, but it is not clear how
the endothelial cytoskeleton manages to open and close a transmigratory channel. Atomic force microscopy was used to investigate
the endothelial cytoskeleton. In order to directly access the leukocyte–endothelial interaction site, we applied a special
protocol (“nanosurgery”). As a result, the endothelial cell turned out to become softer in a confined region strictly underneath
the leukocyte. Fluorescence microscopy confirmed a depolymerization of the f-actin strands at the invasion site. Leukocytes
dramatically rearrange the endothelial cytoskeleton to form transmigratory channels. 相似文献
957.
Amanda J. Albrecht 《Journal of solid state chemistry》2011,184(7):1591-8629
Four thorium sulfate compounds have been synthesized and characterized. [Th(SO4)2(H2O)7]·2H2O (ThS1) crystallizes in space group P21/m, a=7.2488(4), b=12.1798(7), c=8.0625(5) Å, β=98.245(1)o; Na10[Th2(SO4)9(H2O)2]·3H2O (ThS2), Pna21, a=17.842(2), b=6.9317(8), c=27.550(3) Å; Na2[Th2(SO4)5(H2O)3]·H2O (ThS3), C2/c, a=16.639(2), b=9.081(1), c=25.078(3) Å, β= 95.322(2)o; [Th4(SO4)7(OH)2(H2O)6]·2H2O (ThS4), Pnma, a=18.2127(9), b=11.1669(5), c=14.4705(7) Å. In all cases the Th cations are coordinated by nine O atoms corresponding to SO4 tetrahedra, OH groups, and H2O groups. The structural unit of ThS1 is an isolated cluster consisting of a single Th polyhedron with two monodentate SO4 tetrahedra and seven H2O groups. A double-wide Th sulfate chain is the basis of ThS2. The structures of ThS3 and ThS4 are frameworks of Th polyhedra and sulfate tetrahedra, and each contains channels that extend through the framework. One of the Th cations in ThS3 is coordinated by a bidentate SO4 tetrahedron, and ThS4 is unusual in the presence of a pair of Th cations that share a polyhedral face. 相似文献
958.
Melzig L Metzger A Knochel P 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(10):2948-2956
A variety of unsaturated thioethers have been subjected to cross‐coupling reactions with functionalized zinc reagents in the presence of a transition‐metal catalyst. Three different catalytic systems based on Pd(OAc)2 or [Ni(acac)2] and the ligands S‐Phos or DPE‐Phos gave the best results. N‐Heterocyclic thioethers based on a pyridine, pyrimidine, pyrazine, pyridazine, triazine, benzothiazole, benzoxazole, pyrrole, or quinazoline ring, as well as thiomethylacetylenes, serve as electrophiles in this cross‐coupling reaction. Aryl‐, heteroaryl‐, benzylic, and alkylzinc halides with sensitive functionalities, such as ester, nitrile, or ketone groups react at ambient temperature with unsaturated thioethers using a Ni catalyst. The corresponding Pd‐catalyzed reactions require slightly higher temperatures. Large‐scale cross‐coupling experiments (10–20 mmol) with N‐heterocycles are also reported. 相似文献
959.
Xueli Han Ernie Pan Ali Sangghaleh John Albrecht 《International Journal of Solids and Structures》2014
In some piezoelectric semiconductors and ceramic materials, dislocations can be electrically active and could be even highly charged. However, the impact of dislocation charges on the strain and electric fields in piezoelectric and layered structures has not been presently understood. Thus, in this paper, we develop, for the first time, a charged three-dimensional dislocation loop model in an anisotropic piezoelectric bimaterial space to study the physical and mechanical characteristics which are essential to the design of novel layered structures. We first develop the analytical model based on which a line-integral solution can be derived for the coupled elastic and electric fields induced by an arbitrarily shaped and charged three-dimensional dislocation loop. As numerical examples, we apply our solutions to the typical piezoelectric AlGaN/GaN bimaterial to analyze the fields induced by charged square and elliptic dislocation loops. Our numerical results show that, except for the induced elastic (mechanical) displacement, charges along the dislocation loop could substantially perturb other induced fields. In other words, charges on the dislocation loop could significantly affect the traditional dislocation-induced stress/strain, electric displacement, and polarization fields in piezoelectric bimaterials. 相似文献
960.
Albrecht Seelmann 《Integral Equations and Operator Theory》2014,79(4):579-597
An analogue of the Davis-Kahan \({\sin 2\Theta}\) theorem from (SIAM J Numer Anal 7:1–46, 1970) is proved under a general spectral separation condition. This extends the generic \({\sin 2\theta}\) estimates recently shown by Albeverio and Motovilov in (Complex Anal Oper Theory 7:1389–1416, 2013). The result is applied to the subspace perturbation problem to obtain a bound on the arcsine of the norm of the difference of the spectral projections associated with isolated components of the spectrum of the unperturbed and perturbed operators, respectively. 相似文献