3,455 research outputs found

    Anharmonic effect on lattice distortion, orbital ordering and magnetic properties in Cs2AgF4

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    We develop the cluster self-consistent field method incorporating both electronic and lattice degrees of freedom to study the origin of ferromagnetism in Cs2_{2}AgF4_{4}. After self-consistently determining the harmonic and anharmonic Jahn-Teller distortions, we show that the anharmonic distortion stabilizes the staggered x2^{2}-z2^{2}/y2^{2}-z2^{2} orbital and ferromagnetic ground state, rather than the antiferromagnetic one. The amplitudes of lattice distortions, Q2_{2} and Q3_{3}, the magnetic coupling strengthes, Jx,y_{x,y}, and the magnetic moment, are in good agreement with the experimental observation.Comment: 13 pages, 5 figure

    (E)-Ethyl N′-(3-hy­droxy­benzyl­idene)hydrazinecarboxyl­ate dihydrate

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    The asymmetric unit of the title compound, C10H12N2O3·2H2O, contains two organic mol­ecules with similar conformations and four water mol­ecules. Each organic mol­ecule is close to planar (r.m.s. deviations = 0.035 and 0.108 Å) and adopts a trans conformation with respect to its C=N bond. In the crystal, the components are linked into a three-dimensional network by N—H⋯O, O—H⋯O, O—H⋯N and C—H⋯O hydrogen bonds, some of which are bifurcated. An R 2 2(8) loop occurs between adjacent organic mol­ecules

    Placement study of composite vibration isolation system for machinery equipment

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    In traditional vibration isolation and placement studies, vibration participation of foundation is often ignored, and optimizations are focused on the improvements of isolated object and isolation system. In this paper, clamped thin plate was considered as the foundation, and "machinery equipment vibration isolator foundation" was proposed as a composite vibration isolation system. Based on the theory of mechanical fourpole connection, transmitted force from equipment to plate was derived, and the intermediate variable was the displacement admittance of contact points (isolators) on the plate. To peruse the optimal placement, a novel procedure has been programmed, and two cases of arrangement direction have been involved. This study could give a lot of inspiration for vibration isolation and placement strategies of engineering equipment so that extended researches based on this could be performed

    Multi-objective optimization of parameters and location of passive vibration isolation system excited by clamped thin plate foundation

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    This paper reports a novel optimization strategy combined with artificial intelligence for parameters and location design of precision equipment and provides a broader view for traditional passive vibration isolation. It also considers "precision equipment-vibration isolators-thin plate foundation" as a composite passive vibration isolation system and the clamped thin plate. The vibration isolation system is considered as four-point support, and the displacement amplitude transmissibility from the thin plate to precision equipment is derived and based on the analysis of influencing factors of transmissibility; subsequently, multi-objective optimization of the composite system is performed. A novel swarm intelligence multi-objective optimization method—a multi-objective particle swarm optimization (MOPSO) algorithm is adopted in this paper which can achieve a global optimal solution and by selecting the desired solution from an equivalence relation, the whole Pareto set can be avoided. The maximum and variance of the four transmitted peak displacements are simultaneously considered as fitness functions, and the purpose is to reduce the amplitude of the multi-peak isolation system, and in the meantime,  to allow the plate to be uniformly vibrated as far as possible. Moreover, the presented idea is validated numerically, and the location research of the precision equipment mounted on the plate is also conducted

    Absorption, Distribution and Excretion of 14C-Probimane in Mice Bearing Lewis Lung Carcinoma

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    Spontaneous neoplasm metastasis, a fatalist pathological feature of cancer, is a long-evolving, multi-steps process that can now only be treated or controlled by drugs or immuno-modulators. Probimane (Pro), as a representative of the well-known class of antimetastatic agents ‘Bisdioxopiperazine compounds (Biz)’, is systematically studied for its absorption, distribution and excretion in mice bearing Lewis lung carcinoma by a radioactivity-detective method in this investigation. It is found that the 14C-Pro concentrations in different normal organs of mice at 2 hrs are very high and dramatically declined at 24 and 48 hrs. However, Pro concentrations in metastatic foci are slightly changed at the same time. Almost no change of Pro concentrations is observed in pulmonary metastatic nodules within 48 hrs. This evidence can be used to explain the characteristics of good metastatic inhibition by Biz compounds. The radioactivity in brain is relatively low because Pro can hardly penetrate into the blood-brain-barrier to eliminate brain tumors. The excretion of 14C-Pro is observed at the same ratios from both urine and feces and also at constant rates. These data are much useful for better understanding of the general pharmacological characters and possible antimetastatic mechanisms of actions of probimane and other Biz compounds from a new perspective and research angles

    Different Spontaneous Pulmonary Metastasis Inhibitions against Lewis Lung Carcinoma in Mice by Bisdioxopiperazine Compounds of Different Treatment Schedules

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    Spontaneous neoplasm metastasis, a fatalist pathological feature of cancer, is a long-evolving, multi-steps process that can now only be treated or controlled by drugs or immuno-modulators. As we have previously hypothesized, each drug or immuno-modulator might act differently within various stages of a metastasis. Therefore any researches helping to determine these differences will be beneficial for updating therapeutics for metastasis. In this work, we have testified this hypothesis by using a series of well-known anti-metastatic agents – Bisdioxopiperazine compounds

    Electronic structure, mechanical and thermodynamic properties of ThN from first-principles calculations

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    Lattice parameter, electronic structure, mechanical and thermodynamic properties of ThN are systematically studied using the projector-augmented-wave method and the generalized gradient approximation based on the density functional theory. The calculated electronic structure indicates the important contributions of Th 6\emph{d}and 5\emph{f} states to the Fermi-level electron occupation. Through Bader analysis it is found that the effective valencies in ThN can be represented as Th+1.82^{+1.82} N1.82^{-1.82}. Elastic constant calculations shows that ThN is mechanically stable and elastically anisotropic. Furthermore, the melting curve of ThN is presented up to 120 GPa. Based on the phonon dispersion data, our calculated specific heat capacities including both lattice and conduction-electron contributions agree well with experimental results in a wide range of temperature.Comment: 16 pages, 8 figure

    Plasmoid ejection and secondary current sheet generation from magnetic reconnection in laser-plasma interaction

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    Reconnection of the self-generated magnetic fields in laser-plasma interaction was first investigated experimentally by Nilson {\it et al.} [Phys. Rev. Lett. 97, 255001 (2006)] by shining two laser pulses a distance apart on a solid target layer. An elongated current sheet (CS) was observed in the plasma between the two laser spots. In order to more closely model magnetotail reconnection, here two side-by-side thin target layers, instead of a single one, are used. It is found that at one end of the elongated CS a fan-like electron outflow region including three well-collimated electron jets appears. The (>1>1 MeV) tail of the jet energy distribution exhibits a power-law scaling. The enhanced electron acceleration is attributed to the intense inductive electric field in the narrow electron dominated reconnection region, as well as additional acceleration as they are trapped inside the rapidly moving plasmoid formed in and ejected from the CS. The ejection also induces a secondary CS
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