非空气-石英结构PCF的带隙特性分析

光子晶体光纤是近十来年兴起的一个新兴的研究领域,是现今纤维光学的研究重点,光子带隙特性是光子晶体光纤区别传统光纤的主要特征。本文利用全矢量平面波展开法对非空气-石英结构PCF的带隙特性进行分析,并且重点讨论空气孔内填充介电材料对光子带隙存在的影响。     

Extremely narrowed spontaneous emission spectrum induced by elliptically polarized light

Abstract

We demonstrate the control of spontaneous emission from a five-level atom embedded in a modified reservoir under the action of a single control beam with elliptical polarization. For different initial-state preparations, we take into account the influence of the phase difference between the two circularly polarized components of the control beam on the behavior of spontaneous emission. For the ground initial states, the spontaneous emission spectrum usually shows ultranarrow central lines which are greatly enhanced. In contrast, for the excited initial states, these enhanced ultranarrow lines are significantly suppressed due to the destructive quantum interference. Furthermore, our numerical simulations indicate that the multipeak structure appears in the presence of the elliptically polarized control beam and external magnetic field. Such a scheme for controlling spontaneous emission may find applications in high-precision spectroscopy.     

含稀土铜基超细合金粉末在金刚石圆锯片上的应用研究

文章介绍了含稀土铜基超细合金粉末在金刚石圆锯片上的应用。对锯片刀头硬度进行了测试,并开展了锯片切割试验,结果表明：含稀土La和Y锯片刀头的硬度高于未添加稀土锯片（A锯片）和Co基锯片;在同一水平的锋利度方面,含La锯片使用寿命比A锯片和Co基锯片短,而含Y锯片的寿命比A锯片和Co基锯片都有不同程度的延长,切割性能改善明显。     

Undercooling associated with slow freezing and its influence on the microstructure and properties of rice starch gels

It is well accepted that high undercooling or supercooling usually produces numerous small ice crystals. This paper shows that if heat transfer is not rapid enough, high undercooling causes non-homogenous sized ice crystals. Three freezing regimes (i.e. fast, slow and slow with undercooling) were used in this study. Fast freezing produced numerous homogeneously small ice crystals embedded in a thin rice starch gel matrix. This microstructure caused low % syneresis and hardness versus slow freezing’s rather homogenous distribution of fewer large ice crystals embedded in a thicker gel matrix resulting in high % syneresis and hardness. However, slow freezing with undercooling produced non-homogenous clusters involving small and large ice crystals embedded in a very thick gel matrix. Starch retrogradation before ice formation played an important role in this frozen structure. The information gained from this study enhances understanding of the behavior of starch-based food during freezing and storage.     

Single‐cell protein production through microbial conversion of lignocellulosic residue (wheat bran) for animal feed

Agricultural residue (wheat bran) rich in carbohydrates was utilized in the fermentation process to produce microbial biomass. Single‐cell biomass consists of the dried cells of microorganisms, which are used as protein supplements in human food and in animal feed. In the present study, two different microorganisms (Candida utilis and Rhizopus oligosporus) were studied for biomass production. To enhance the nutritional contents of wheat bran, a number of different fermentation parameters (effect of inoculum size, age of inoculum, incubation period, moisture to substrate ratio and incubation temperature) were optimized. Maximum yield was obtained at an inoculum size of 10% (v/w), with the age of the inoculum being a 48 h old culture. A fermentation period of 48 h was found to give the maximum protein yield and viable counts of yeast cells and mould hyphae. The microorganisms showed good growth at 30 °C. After complete optimization of the fermentation parameters, a batch of wheat bran was fermented with C. utilis and R. oligosporus under the optimized conditions, resulting in a maximum crude protein yield of 41.02% compared with the 4.21% crude protein of the non‐fermented wheat bran. Copyright © 2015 The Institute of Brewing & Distilling     

啤酒混合废水发酵菌种筛选及工艺条件的研究

本文选用了产朊假丝酵母（Candida uticis）、脆壁酵母（Saccharomyces fragffis）和酿酒酵母（Saccharomyces cerevisiae）三个菌种进行了啤酒混合废水单细胞蛋白（SCP）发酵条件和菌种筛选试验。结果表明，对于单菌种发酵，产朊假丝酵母是能充分利用啤酒混合废水培养单细胞蛋白的较好菌种，它的生物量和化学需氧量（COD）去除率均为最高，其最佳培养条件分别为：接种量为15％和5％，培养时间为72h和48h，废水浓度为1：3和1：2。而对于混合菌种协同发酵而言，生物量和COD去除率的优选方案分别为：菌种均为产朊假丝酵母：酿酒酵母=1：1，接种量为10％和5％，培养时间72h和48h。     

中国金刚石使用历史超过4500年

通过在国际学术界首次破解夜明珠这一世界性的自然、历史、文化千古之谜和首次创立金刚石考古地质学的理论和方法,以夜明珠就是中国古代巨粒金刚石为例,证明了中国巨粒金刚石开发利用的历史可以一直追溯到4000年前的尧、舜、禹时期甚至4500年前的炎帝时期。这一成果将之前国际学术界普遍认为人类使用金刚石不超过2500年的历史推前了至少2000年,比起哈佛学者使用物理学方法研究刚玉石斧得出中国人使用金刚石粉末加工刚玉石器历史超过4500年的类似结论领先了一年左右的时间。     

气雾化FeNi粉末触媒及合成金刚石的特性

文章主要介绍了气雾化方法制备F eN i粉末触媒的物理特性、显微组织结构和-200目F eN i粉末触媒的粒度组成。利用-200目F eN i粉末触媒合成的金刚石大多为六-八面体,晶型完整,颜色金黄,包裹体少,其T I和TT I(1100℃)性能良好。