Lanthanide(III)/pyrimidine-4,6-dicarboxylate/oxalate extended frameworks: a detailed study based on the lanthanide contraction and temperature effects

Detailed structural, magnetic, and luminescence studies of six different crystalline phases obtained in the lanthanide/pyrimidine-4,6-dicarboxylate/oxalate system have been afforded: {[Ln(μ-pmdc)(μ-ox)(0.5)(H(2)O)(2)]·3H(2)O}(n) (1-Ln), {[Ln(μ-pmdc)(μ-ox)(0.5)(H(2)O)(3)]·2H(2)O}(n) (2-Ln), {[Ln(μ(3)-pmdc)(μ-ox)(0.5)(H(2)O)(2)]·~2.33H(2)O}(n) (3-Ln), {[Ln(2)(μ(3)-pmdc)(μ(4)-pmdc)(μ-ox)(H(2)O)(3)]·5H(2)O}(n) (4-Ln), {[Ln(μ(3)-pmdc)(μ-ox)(0.5)(H(2)O)(2)]·H(2)O}(n) (5-Ln), and [Ln(pmdc)(1.5)(H(2)O)(2.5)] (6-Ln). The slow generation of the oxalate (ox) anion, obtained from the in situ partial hydrothermal decomposition of the pyrimidine-4,6-dicarboxylate (pmdc) ligand, allows us to obtain good shaped single crystals, while direct addition of potassium oxalate provides the same compounds but as polycrystalline samples. The crystal structures of all compounds are based on the double chelation established by the pmdc and ox ligands to provide distorted 2D honeycomb layers that, in some cases, are fused together, leading to 3D systems, by replacing some of the coordinated water molecules that complete the coordination sphere of the lanthanide by uncoordinated carboxylate oxygen atoms of the pmdc. The presence of channels occupied by crystallization water molecules is also a common feature with the exception of compounds 5-Ln. It is worth noting that compounds 3-Ln present a commensurate crystal structure related to the partial occupancy of the crystallization water molecules placed within the channels. Topological analyses have been carried out, showing a previously nonregistered topology for compounds 4-Ln, named as jcr1. The crystal structures are strongly dependent on the lanthanide ion size and the temperature employed during the hydrothermal synthesis. The lanthanide contraction favors crystal structures involving sterically less hindranced coordination environments for the final members of the lanthanide series. Additionally, reinforcement of the entropic effects at high temperatures directs the crystallization process toward less hydrated crystal structures. The magnetic data of these compounds indicate that the exchange coupling between the lanthanide atoms is almost negligible, so the magnetic behavior is dominated by the spin-orbit coupling and the ligand field perturbation. The luminescence properties that exhibit the compounds containing Nd(III), Eu(III), and Tb(III) have been also characterized.     

中国区域间技术创新的空间溢出效应研究

本文结合新经济地理学K关联的思想构造了外部技术创新溢出指数模型,在此基础上运用2006~2014年中国30个省级行政区的面板数据对中国区域间技术创新空间溢出效应进行了实证研究,结果表明:(1)全国技术创新溢出效应主要是东部地区带动的,东部地区的省份对东部、中部和西部地区其他省份存在技术创新溢出效应,而中部和西部并没有对其他地区技术创新产生溢出效应,并且中部地区和西部地区内部各省之间存在竞争效应。(2)无论是全国还是东部、中部和西部地区,R&D经费、R&D人员和知识存量均对技术创新产生正向作用,并且这些地区的技术创新产出均处于规模报酬递减阶段,不同的是,全国、东部和中部地区R&D人员对技术创新的贡献比R&D资本要大,而西部地区R&D资本对技术创新的贡献则要大于R&D人员。     

电容应变式压力传感器原理及检测电路设计

论述了电容应变式压力传感器的原理，给出了一种电容应变式压力传感器的电路，并分析了压力大小与电路输出电压之间的关系。     

On the Stability of Equilibria in Two-Degrees-of- Freedom Hamiltonian Systems Under Resonances

We consider the problem of stability of equilibrium points in Hamiltonian systems of two degrees of freedom under resonances. Determining the stability or instability is based on a geometrical criterion based on how two surfaces, related with the normal form, intersect one another. The equivalence of this criterion with a result of Cabral and Meyer is proved. With this geometrical procedure, the hypothesis may be extended to more general cases.     

A General Random Walk Model of Molecular Motor

A general random walk model framework is presented which can be used to statistically describe the internaldynamics and external mechanical movement of molecular motors along filament track. The motion of molecular motorin a periodic potential and a constant force is considered. We show that the molecular motor‘s movement becomesslower with the potential barrier increasing, but if the forceis increased, the molecular motor‘s movement becomesfaster. The relation between the effective rate constant and the potential barrier‘s height, and that between the effectiverate constant and the value of the force are discussed. Our results are consistent with the experiments and relevanttheoretical consideration, and can be used to explain some physiological phenomena.     

蜡烛火焰三维温度场重建实验研究

本文在实验室中以蜡烛火焰为研究对象,研究采用辐射图像处理技术重建蜡烛三维温度场。并采用细丝热电偶实测火焰局部温度,对蜡烛火焰三维温度场可视化的结果进行了比较。结果表明,火焰高温区的重建温度是合理的,此方法能够很好地重建单峰、双峰三维温度分布。进一步证实了基于火焰图像处理技术实现三维温度场可视化的可行性。     

Obstacle Effects on One-Dimensional Translocation of ATPase

We apply a general random walk model to the study of the ATPase‘s one-dimensional translocation along obstacle biological environment, and show the effects of random obstacles on the ATPase translocation along single stranded DNA. We find that the obstacle environment can reduce the lifetime of ATPase lattice-bound state which results in the inhibition of ATPase activity. We also carry out the ranges of rate constant of ATPase unidirectonal translocation and bidirectional translocation. Our results are consistent with the experiments and relevant theoretical consideration, and can be used to explain some physiological phenomena.     

Sol-Gel Deposited Sb-Doped Tin Oxide Films

The structural, electrical and optical properties of single sol-gel derived antimony-doped tin oxide (ATO) films sintered at 550°C have been measured. The reproducibility of both the preparation and the characterization procedures have been tested by a round-robin test involving eight laboratories within a Concerted European Action (CEA) project. The resistivity measured as a function of Sb content has been obtained by electric and reflectance and transmission measurements. Their differences are discussed in terms of structural and grain boundary effects. An increase of Sb content results in a decrease of the crystallite size (7.0 to 5.4 nm) and a greater influence of the grain boundary.     

A Novel Fabrication Technique of Long Period Fiber Gratings

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Radiative signal for supersymmetric particle production in photon-electron collisions

We discuss the production of gauginos and selectrons accompanied by photon emission in high energy scattering of real photons off electrons.