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41.
Summary An analysis is presented of the dynamic behavior and permanent deformation of a rigid-perfectly plastic beam subjected to blast-type loading. The beam is simply supported at the ends, and the load is uniformly distributed over the span. The anaylsis is based on an approximate yield curve relating limiting values of shear force and bending moment. Various patterns of deformation are found to occur with combination of plastic bending and shear sliding depending upon the load magnitude and beam characteristics. The effects of shear and of the shape of the load pulse are examined, and the paper is concluded with the results expressed in general terms for application to similar cases.
The essential part of the material presented in this paper was prepared while the author was engaged in graduate study at Brown University, under the general guidance of Prof. P. S. Symonds, to whom the author wishes to express his gratitude. 相似文献
Übersicht Das dynamische Verhalten und die Dauer-Verformung eines ideal starr-plastischen Balkens unter dem Einfluß von Stoßbelastungen wird untersucht. Die Belastung ist gleichmäßig über die Länge des an den Enden einfach gelagerten Balkens verteilt. Den Untersuchungen wird eine genäherte Fließkurve zugrunde gelegt, bei der die Grenzwerte für Schubkraft und Biegemoment in Beziehung gesetzt werden. Abhängig von der Belastungsgröße und von den Balkenparametern werden verschiedenartige Deformationsmuster gefunden, bei denen plastisches Biegen und Schubgleiten kombiniert auftreten. Der Einfluß der Form des Belastungsimpulses und des Schubes wird untersucht. Abschließend werden die Ergebnisse in allgemeiner Form ausgedrückt um sie so für ähnliche Fälle anwendbar zu machen.
The essential part of the material presented in this paper was prepared while the author was engaged in graduate study at Brown University, under the general guidance of Prof. P. S. Symonds, to whom the author wishes to express his gratitude. 相似文献
42.
Yamaguchi K Ueki R Nonaka H Sugihara F Matsuda T Sando S 《Journal of the American Chemical Society》2011,133(36):14208-14211
Monoamine oxidase (MAO) A is a flavoenzyme that catalyzes the oxidation of biologically important monoamines and is thought to be associated with psychiatric disorders. Here, we report a strategy for rationally designing a (19)F magnetic resonance imaging probe for the specific detection of human MAO-A (hMAO-A) activity. Our designed (19)F probe was oxidized expeditiously by hMAO-A to produce 2-fluoro-4-nitrophenol via a spontaneous β-elimination mechanism. Concomitant with the structural change of the probe to the product, the (19)F chemical shift changed by 4.2 ppm, which was enough to visualize the probe and enzymatic product separately. Importantly, our probe achieved excellent discrimination of hMAO-A from its isoform hMAO-B. 相似文献
43.
We propose a modified mechanism for the inhibition of [NiFe]hydrogenase ([NiFe]H(2)ase) by CO. We present a model study, using a NiRu H(2)ase mimic, that demonstrates that (i) CO completely inhibits the catalytic cycle of the model compound, (ii) CO prefers to coordinate to the Ru(II) center rather than taking an axial position on the Ni(II) center, and (iii) CO is unable to displace a hydrido ligand from the NiRu center. We combine these studies with a reevaluation of previous studies to propose that, under normal circumstances, CO inhibits [NiFe]H(2)ase by complexing to the Fe(II) center. 相似文献
44.
Kuma S Nakahara H Tsubouchi M Takahashi A Mustafa M Sim G Momose T Vilesov AF 《The journal of physical chemistry. A》2011,115(25):7392-7399
Clusters of tetracene molecules with different numbers of attached (Ar)(N), (Ne)(N) and (H(2))(N) particles (N = 1-2000) are assembled inside superfluid He nanodroplets and studied via laser-induced fluorescence. The frequency shift of the fluorescence spectrum of the tetracene molecules is studied as a function of cluster size and pickup order of tetracene and cluster species. For (Ar)(N) and (Ne)(N) clusters, our results indicate that the tetracene molecules reside inside the clusters when tetracene is captured by the He nanodroplet before the cluster species; conversely, the tetracene molecules stay on the surface of the clusters when tetracene is captured after the cluster species. In the case of (H(2))(N) clusters, however, tetracene molecules reside inside the (H(2))(N) clusters irrespective of the pickup order. We conclude that (Ar)(N) and (Ne)(N) clusters are rigid at T = 0.38 K, while (H(2))(N) clusters of up to N = 2000 remain fluxional at the same temperature. The results may also indicate the occurrence of heterogeneous nucleation of the (H(2))(N) clusters, which is induced by the interaction with tetracene chromophore molecules. 相似文献
45.
46.
We propose a sinusoidal wavelength-scanning interferometer for measuring thickness and surface profile of a thin film. The interference signal contains phase modulation amplitude Z and phase $aL which are related to the positions and profiles of the reflecting surfaces, respectively. By reducing the difference between the detected signal and the estimated signal using the multidimensional nonlinear least-squares algorithm, we estimate values of Z and $aL. Experimental results show that the front and rear surfaces of a silica glass plate of 20 $mUm-thickness could be measured with an error less than 10 nm. 相似文献
47.
We propose a photothermal phase-modulating laser diode interferometer equipped with a high-speed feedback control system. The CCD camera’s shutter-function raises the modulating frequency, which in turn elicits a higher feedback response, thus enabling us to eliminate nearly all external disturbance. With the recent application of a system purpose-built for discriminating between numerous fringe sequences, we have also reduced processing time. 相似文献
48.
Takamasa Ohno Munehiro Nakagawa Yun-Mo Li Hajime Mizukami 《Tetrahedron letters》2005,46(50):8657-8660
In the present study, new sesquiterpene lactones (1) and (2) were isolated from the EtOAc soluble fraction of the water extract of Linderae Radix through bioassay-guided fractionation and isolation methods. The structure of these compounds was elucidated by spectroscopic analysis of their 2D NMR spectra, including COSY, HMBC, and HMQC techniques. Two isolates showed significant cytotoxicity against the human small cell lung cancer cell SBC-3, and lesser cytotoxicity against mouse fibroblast cell 3T3-L1. 相似文献
49.
Takamasa Kinoshita Daisuke Icbinari Junko Sinya 《Journal of heterocyclic chemistry》1996,33(4):1313-1317
The Birch reduction-alkylation of some N,N-dialkylfuramides and its application to the useful intermediates for the natural product synthesis are described. 相似文献
50.
Film preparation of oxide superconductors, mainly of the 1-2-3 (RBa2Cu3Ox) and Bi-containing (Bi-Sr-Ca-Cu-O) systems, by evaporation of either metals or metal compounds by low pressure is summarized, with a particular focus on the development of oxidation sources essential to the technique. Oxidizing reagents that enable the oxidation of metal evaporates to take place in high (0·1 to 10?3 Pa) or even ultra-high (<10?5 Pa) vacuum are summarized using the experiments of those who tried to apply the molecular beam epitaxy method to atomically controlled fabrication of thin films of the material, especially for device processing. The evaporation in various kinds of oxidizing atmosphere, including the simple method of in situ annealing of the metal layers in oxygen to the more advanced in situ preparation of the films with strong oxidizing reagents such as atomic oxygen, ozone, nitric oxide, etc. along with the thermochemistry of the oxidation of metals by low pressure with these reagents is reviewed. 相似文献