Frustrated structure of an anticlinic-like smectic-C phase

We present a polarising optical microscopy study of the low-temperature anticlinic-like tilted mesophase of the liquid-crystal compound octylphenyl-2-chloro-4-(p-cyano-benzoyloxy) (DB₈Cl). This mesophase has been described as a bilayer smectic structure in which the molecules within each layer are organised in an anticlinic way. The optical textures observed in samples with planar orientation show a double stripe pattern, with the lines aligned parallel to the rubbing direction, characteristic of a double periodic modulation of the refractive index of the material. The long-period modulation is temperature dependent and disappears for thin sample cells (< 5μm). The short-period modulation is nearly independent of the thickness of the cells. The experimental results are analysed in terms of a model which considers that there is a special distribution of the principal optical axis which may be in or out of the polariser-analyser plane. The observed periodic variation of the principal optical axis could not be interpreted in terms of the original structure proposed for this phase. DB₈Cl presents a structure formed by dimers that can be viewed as flexible bent-core-like molecules, showing similarities with phases found in banana-like systems, but exhibiting a much more complex structure.     

MJ and collision energy dependent attenuation of Rg (3P2) by CF3Br

The total attenuation cross-section of Rg (³P₂) (Rg = Ar, Kr) by the collision with CF₃Br is measured as a function of the magnetic sub level M_J of Rg (³P₂) and the collision energy. For Ar (³P₂), the attenuation process indicates a M_J dependence, in particular, the cross-section of the M_J = 0 state is lower compared with that for other states. On the other hand, Kr (³P₂) shows no M_J dependent attenuation.     

Spherophylon,the concept of life at a level higher than that of the individual

A new term, spherophylon, indicates a unit of life higher than the individual level. To define this term, critical notes are given on the meaning of age in terms of life, the interrelationships among the elements of biodiversity, and an analogy of development between the multicellular body of an individual and the spherophylon. Life is compared at various levels; at the level of the cell, the individual as a multicellular organism, and the spherophylon. The biology of the spherophylon is discussed in the context of integrative biology.     

水稻秸秆接力处理过程中的红外光谱研究

作物秸秆就地焚烧已经和正在引起严重的大气污染,土壤微生物对作物秸秆的较难分解是作物秸秆农业利用的主要限制因子之一。文章采用傅里叶红外光谱(FTIR)分析技术对水稻秸秆接力处理(化学水解—微生物培养)过程进行了研究,分析探讨了接力处理的化学机理。由红外光谱的分析可见,经过接力处理,水稻秸秆半纤维素和纤维素大大降低,C／N比也降低到适合微生物生长的范围,硅元素的含量也降低,水溶性的物质含量升高,其结果与化学分析的结果一致。文章提出的水稻秸秆接力处理方法能为作物秸秆的农业利用提供有效途径。     

塑料光纤拉丝塔控制系统设计

为减小塑料光纤纤芯直径波动造成的非固有散射损耗,设计了一种新型光纤拉丝塔控制系统,详细阐述了其工作原理及软硬件实现过程。采用单片机作为核心处理部件,合理设计传感器测温电路、加热炉温度控制电路、直径测量和控制电路以及友好的人机界面。实验表明系统拉丝芯径范围宽(0.2～3mm),拉制光纤直径均匀,精度可控制在15μm以内。整个系统成本低,实用价值高,满足塑料光纤实验室研究需要,可供实际生产参考。     

Momentum space distribution of electrons in an atom using hydrogenic wave functions

A formulation is developed to derive exact analytic expressions for electron-electron correlation and density of electrons in momentum space using hydrogenic wave functions. It is shown that for large atoms the expression for density of electrons has a simple form.     

激光束准直检测仪：原理,功能与精度

根据先前曾提出的单楔板旋转原理与实验研究,一种定量检测光学系统离焦量及激光发散度的仪器已经研制成功.本文概括地介绍了该仪器原理、主要功能、测试方法及精度评价等.由于本仪器具有一系列优点,已成为激光实验、光学教学及光学工程必备的仪器