Improved production of spiramycin by mutant<Emphasis Type="Italic">Streptomyces ambofaciens</Emphasis>

Strain improvement and medium optimization to increase the productivity of spiramycin were carried out. Of oil tolerant mutant strains screened, one mutant,Streptomyces ambofaciens XC 2–37, produced 9% more spiramycin than the parent strainS. ambofaciens XC 1–29. The effects of soybean oil and propyl alcohol on spiramycin production withS. ambofaciens XC 2–37 were studied. The potency ofS. ambofaciens XC 2–37 was improved by 61.8% with addition of 2% soybean oil in the fermentation medium and 0.4% propyl alcohol at 24 hours after incubation. The suitable time for feeding propyl alcohol is at 24 hours after incubation in flask fermentation and at 20 hours after incubation in fermentor fermentation. The new process withS. ambofaciens XC 2–37 was scaled up for industrial scale production of spiramycin in a 60 m³ fermentor in Xinchang Pharmaceutical Factory, Zhejiang Medicine Company, Ltd., China, and the potency and productivity of fermentation were improved by 42.9%.     

Experimental study on the spatial distribution of particle rotation in the upper dilute zone of a cold CFB riser

Particle rotation plays an important role in gas-solid flows. This paper presents an experimental investigation on the spatial distribution of average rotation speed for glass beads in the upper dilute zone of a cold circulating fluidized bed （CFB） riser. It is shown that in the horizontal direction, the average rotation speed in the near-wall area is larger than that in the center area, while in the vertical direction, it decreases as the height increases. The reason resulting in this distribution is analyzed by considering several factors including particle size, particle shape, particle number density, particle collision behavior, and the surrounding flow field, etc. The effects of CFB operation conditions on the spatial distribution of average rotation speed are also studied. The results show that the increasing superficial gas velocity increases the average rotation speed of particles in the near wall area but takes nearly no effect on that in the center area. The external solids mass flux, however, takes the opposite effect. It is found that the average rotation speeds of particles in both areas are increased as the total amount of bed material increases.     

困境与出路:地方农业高校青年教师综合能力培养——以M农业大学为例

青年教师是高校师资的后备力量,对推动高校人才培养和促进教学质量提升具有重要作用。为破解M农业大学青年教师综合能力培养存在的重引进轻培育、缺乏顶层设计、目标定位模糊、考评机制欠缺、考研精力不足、科研平台不足等困境,提出了不着眼于高配而着眼于标配、做好顶层设计、目标定位要明确、完善绩效考评机制、加强科研引导、加强科研平台建设等对策建议,为M农业大学制订青年教师培养政策方案提供理论支撑与实践指导。     

从清代竹枝词看京城文化时尚

清代文人曾写过不少咏育北京风土人情的竹枝词，形象生动地反映了当时京城各类人士的文化娱乐生活，本文主要从四个方面进行探讨，一是地方戏在京城流行的情况，以及京城人热衷观戏，从而促进戏曲的发展繁荣，二是小说，字画和古玩受到文人格外青睐，京城具有浓厚文化气息，三是教育考试在京城的发达和变化，四是近代文明对京城生活的影响，以及人们观念的更新和文化时尚的变化。     

Effect of particle loading on heat transfer enhancement in a gas-solid suspension cross flow

Heat transfer between gas-solid multiphase flow and tubes occurs in many industry processes, such as circulating fluidized bed process, pneumatic conveying process, chemical process, drying process, etc. This paper focuses on the influence of the presence of particles on the heat transfer between a tube and gas-solid suspension. The presence of particles causes positive enhancement of heat transfer in the case of high solid loading ratio, but heat transfer reduction has been found for in the case of very low solid loading ratio (M _s of less than 0.05 kg/kg). A useful correlation incorporating solid loading ratio, particle size and flow Reynolds number was derived from experimental data. In addition, thek-∈ two-equation model and the Fluctuation-Spectrum-Random-Trajectory Model (FSRT Model) are used to simulate the flow field and heat transfer of the gasphase and the solid-phase, respectively. Through coupling of the two phases the model can predict the local and total heat transfer characteristics of tube in gas-solid cross flow. For the total heat transfer enhancement due to particles loading the model predictions agreed well with experimental data. Project supported by National Natural Science Foundation for Distinguished Young Scholars (No. 50025618)     

WTO金融服务贸易法律制度研究

本文从国际金融服务贸易壁垒的研究着手,论述了WTO金融服务贸易的法律框架,重点阐述了WTO金融服务贸易的基本法律原则,其中又重点对GATS的国民待遇原则、市场准入和最惠国待遇原则作了研究。     

Simulating confined swirling gas-solid two phase jet

A k-ε-kp multi-fluid model was used to simulate confined swirling gas-solid two phase jet comprised of particle-laden flow from a center tube and a swirling air stream entering the test section from the coaxial annular. After considering the drag force between the two phases and gravity, a series of numerical simulations of the two-phase flow of 30μm, 45μm, 60μm diameter particles were performed on a x×r＝50×50 mesh grid respectively. The results showed that the k-ε-kp multi-fluid model can be applied to predict moderate swirling multi-phase flow. When the particle diameter is large, the collision of the particles with the wall will influence the prediction accuracy. The bigger the diameter of the particles, the stronger the collision with the wall, and the more obvious the difference between measured and calculated results.     

职业教育促进中国制造业的提升——国家社会科学基金教育学"十五"规划重点课题"职业教育与中国制造业发展研究"验收略记(二)

制造业领域的职业教育发展现状1.制造业领域中的职业教育规模不断扩大中国制造业的快速发展,对产业工人产生了巨大的需     

《力》单元检测题

一.选择题1.下列说法正确的是()A.力是物体对物体的作用,力总是成对出现的。B.物体受到的重力是由于地球的吸引而产生的。C.描述力只要用一根带箭头的线段表示出力的大小和方向就可以了。D.力的大小用天平来测量。2.有两个物体相互接触,关于接触处的弹力和摩擦力,以下说法正确的是()A.一定有弹力,但不一定有摩擦力。B.如果有弹力,则一定有摩擦力。C.如果有摩擦力,则一定有弹力。D.如果有摩擦力,其大小一定与弹力的大小成正比。3.在力的分解中,有唯一解的条件是:()A.已知两个分力的方向;B.已知两个分力的大小;C.已知一个分力的大小和方…     

似非而是的隽语对现代生活的启示作用

本文介绍了似非而是的隽语(paradox),揭示了它作为一种认知方式,而不是作为一种传统的修辞格对日益发展的现代社会的启示作用:它帮助我们用辨证的观点看问题,从而更透彻地分析现代社会中的矛盾现象,对其进行更深入的思考。隽语该功能的实现有赖于读者头脑中的图式知识,因此本文还从图式角度剖析了隽语的概念表达过程和读者对它的解读过程。