Two photoluminescent pentanuclear homo- and hetero-metal complexes based on benzotriazole bridge

Two new discrete Btz-bridged pentanuclear metal complexes, [HDMF][NaHg₄(Btz)₆I₄] (1) and [Zn₅(Btz)₆(L)₃(Ac)]?·?0.5MeOH?·?0.5H₂O (2) (Btz?=?deprotonated benzotriazole, L?=?p-aminobenzoate, HDMF?=?protonated DMF, and Ac?=?acetate), were synthesized using three-layered diffusion and natural evaporation methods, respectively. In 1, the pentanuclear anion [NaHg₄(Btz)₆I₄]^? is composed of a tetrahedral arrangement of four four-coordinate Hg(II) ions centered on the six-coordinate Na(I), and thereby forming a rare Btz-bridged hetero-metal complex. Compound 2 is a neutral pentanuclear homo-metal complex, consisting of a tetrahedral arrangement of four five-coordinate Zn(II) ions centered on the fifth six-coordinate Zn(II). The thermal stabilities and solid-state photoluminescence of the two complexes have been investigated.     

Recent advances in theoretical models of respiratory mechanics

As an important branch of biomedical engineering, respiratory mechanics helps to understand the physiology of the respiratory system and provides fundamental data for developing such clinical technologies as ventilators. To solve different clinical problems, researchers have developed numerous models at various scales that describe biological and mechanical properties of the respiratory system. During the past decade, benefiting from the continuous accumulation of clinical data and the dramatic progress of biomedical technologies (e.g. biomedical imaging), the theoretical modeling of respiratory mechanics has made remarkable progress regarding the macroscopic properties of the respiratory process, complexities of the respiratory system, gas exchange within the lungs, and the coupling interaction between lung and heart. The present paper reviews the advances in the above fields and proposes potential future projects.     

Mechanical properties of twist grain boundaries in Cu

In a previous paper we studied the Young's and shear modulus of a high-angle twist grain boundary (5) in Cu, using the EAM, and related it to the uniaxial strain derivatives of single crystals. In this paper, we discuss elastic properties of ten additional twist grain boundaries, from 8.8–43.6°. The monolayer Young's modulus at each boundary was calculated and found to be 20–50% higher than the bulk value for all eleven boundaries for both csl and type1 structures. The monolayer shear modulus at each boundary was calculated and found to be 93–98% lower than the bulk value for six grain boundaries with csl structure and found to decrease with increasing twist angle. The critical shear stress was also calculated for eleven boundaries with csl structure and found to roughly decrease with increasing twist angle.     

Heterogeneities of grain boundary arrangement in polycrystals

Data on mutual arrangements of different types of grain boundaries in polycrystals are presented. The heterogeneity in grain boundary distribution, namely, the effect of gathering low-angle or special tilt grain boundaries is found in pure aluminum thin films, in sheets of Fe-3% Si alloy and in Al₂O₃ doped with MgO or MgO and Y ₂O₃. The local texture, i.e., formation of colonies or clusters of close-oriented grains is considered as a reason of this heterogeneity. The influences of grain boundary gathering on the transport properties of polycrystals and on the crack propagation are discussed. A new concept of effective grain size is suggested to analyze the relationship between material microstructures and material properties.     

核压力容器防止辐照脆化的安全评定

本文结合我国核动力反应堆的实例,首先介绍了设计规范中采用的断裂分析图的评定方法,然后着重讨论一种新的断裂力学的评定方法。结合对容器材料断裂韧性的实验测定,给出了计算结果,绘制了全寿期的安全运行工况图,并对两种方法的结果作了比较讨论。     

加速天体的某些热力学性质

本文根据含有较多磁单极的一类加速天体的引力场度?,研究加速天体的某些?力学性质,我们得出结论:(1)具有加速运动的天体,即使不?的转动,也会造成两极与?道间的温差。(2)两个极区温度不同,θ=0的极区温度高于θ?π的极区温度。磁菏q的作用能使天体表面温度降低,使引力半径减小,     

A passive solar heater-refrigerator

Summary In this paper we study the nonequilibrium thermodynamic steady-state behaviour of a model system representing a core surrounded by an envelope in which the envelope interacts with the solar radiation and with an external bath having a given temperature profile. The heat flow between core and envelope can be controlled by varying the thermal conductivity of their interface. We show that this system acts as a passive heat pump raising the core average temperature with respect to the average equilibrium value corresponding to a fixed value of the interface conductivity, at the same time flattening its oscillation in time. By changing the time dependence of the conductivity the systemvice versa acts as a refrigerator. We show how the limits of this performance depend on the passive parameters such as surfaces, conductivities, heat capacities. The periodicity considered in this study is the daily cycle.

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Riassunto In questo lavoro si studia lo stato stazionario di non equilibrio termodinamico per un sistema che rappresenta modellisticamente un corpo circondato da un involucro; questo interagisce con la radiazione solare e con un bagno termico esterno caratterizzato da una temperatura che dipende dal tempo in modo prefissato. Il flusso di calore fra l'interno e l'involucro è controllato variando la conducibilità termica dell'interfaccia. Noi mostriamo che questo sistema funziona come una pompa di calore passiva, cioè innalza la temperatura media dell'interno rispetto a quella che si avrebbe nel caso di conducibilità fissa e, allo stesso tempo, riduce le oscillazioni di codesta temperatura. Semplicemente cambiando la dipendenza oraria del controllo, il sistema funziona come un frigorifero. Si mostra in che modo tale effetto dipenda dai parametri passivi che sono le superfici, i calori specifici, la conducibilità. Consideriamo in questo studio il ciclo giornaliero.

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Резюме В этой работе мы исследуем неравновесное термодинамическое стационарное поведение модельной системы, представляющей ядро, окруженное оболочкой, которая взаимодействует с солнечным излучением и с внешним термостатом, имейщим заданный профиль температур. Поток тепла между ядром и оболочкой можно контролировать посредством изменения теплопровдности их границы раздела. Мы покзываем, что эта система действует, как пассивный тепловой насос, поднимающий среднюю температуру ядра относительно средней равновесной величины, соответствующей фиксировчнной величине теплопроводности границе раздела, и в то же время сглаживающий осцилляции температуры во времени. Изменяя временную зависимость теплопроводности, описанная система может действовать как холодильник. Мы показываем, как указанный эффект зависит от таких пассивных параметров, как поверхности, проводимости, теплоемкости. Периодичность рассмотренной системы представляет суточный цикл.

     

Maximum irreversible availability for continuous systems

Summary In this paper we generalize the study of the irreversible availability, already widely developed for discrete systems, to field theory. We derive the general equations and solve analytically the stationary unidimensional case.

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Riassunto In questo articolo si generalizza lo studio del lavoro estraibile di Gibbs, che è già ampiamente sviluppato nel caso dei sistemi discreti, al formalismo della teoria continua di campo. Si formulano le equazioni differenziali in generale e si risolve analiticamente il caso del problema unidimensionale stazionario.

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Резюме В зтой работе мы обобщаем исследование необратимой доступности, развитое для дискретных систем, для формализма непрерывной теории поля. Мы выводим общие уравнения и решаем аналитически проблему в стационарном одномерном случае.

     

单模光纤波导模的傍轴传输特性

将LP01模表示成用拉盖尔-高斯模线性叠加的形式,利用柯林斯公式推导出单模光纤波导模通过傍轴ABCD光学系统的解析传输公式。用所得的解析公式对LP01模在自由空间的传输和聚焦特性作了研究,并和高斯基模进行了比较。数值计算结果表明,用高斯基模描述LP01模会产生一定误差。LP01模经过透镜聚焦后存在焦移,且焦移随着菲涅尔数传输特性的减小而增大。选择合适的菲涅尔数聚焦后,LP01模会出现长焦深,这是与聚焦的高斯模所不同的。     

ComBn(m+n≤6)团簇的结构，电子特性和磁性研究

基于密度泛函理论和卡里普索结构预测方法,系统研究了ComBn(m+n≤6)团簇的结构,电子特性和磁性。首先,通过卡里普索结构预测方法获得了体系的基态和亚稳态结构。基于基态结构,利用HOMO-LUMO能隙,垂直电离势,垂直电子亲和势和化学硬度分析了掺杂体系的稳定性。最后,研究了基态结构对应的自然布局分布,自然电子组态等电子特性和磁性。