Modulating dopant segregation in floating-zone silicon growth in magnetic fields using rotation

The feasibility of modulating dopant segregation using rotation for floating-zone silicon growth in axisymmetric magnetic fields is investigated through computer simulation. In the model, heat and mass transfer, fluid flow, magnetic fields, melt/solid interfaces, and the free surface are solved globally by a robust finte-volume/Newton's method. Different rotation modes, single- and counter-rotations, are applied to the growth under both axial and cusp magnetic fields. Under the magnetic fields, it is observed that dopant mixing is poor in the quiescent core region of the molten zone, and the weak convection there is responsible for the segregation. Under an axial magnetic field, moderate counter-rotation or crystal rotation improves dopant uniformity. However, excess counter-rotation or feed rotation alone results in more complicated flow structures, and thus induces larger radial segregation. For the cusp fields, rotation can enhance more easily the dopant mixing in the core melt and thus improve dopant uniformity.     

大庆油田水平井漂浮下套管技术研究

在油田开发中、后期,水平井钻井技术对剩余油挖潜举足轻重,是提高原油采收率及开发低渗透油层的重要手段,可降低综合成本、环境污染风险,减少生产占地,有效开发低效储量,提升油气田的产能和开发效益。目前大庆油田水平井随着水平段加长,导致套管下入困难,施工时被迫减少套管扶正器的数量,使套管居中度达不到设计要求,固井质量差。针对这些问题开展了相关技术研究,研制配套了系列工具并形成了一套适合大庆油田水平井漂浮下套管工艺技术,目前现场应用115口井,应用效果良好,提高了套管下入时效及固井质量。     

Pipette vial dispersive liquid–liquid microextraction combined with high‐performance liquid chromatography for the determination of benzoylurea insecticide in fruit juice

A simple, sensitive, and efficient method of using a pipette vial to perform dispersive liquid–liquid microextraction based on the solidification of floating organic droplets was coupled with high‐performance liquid chromatography (HPLC) and a diode array detector for the preconcentration and analysis of four benzoylurea insecticides in fruit juice. In this method, 1‐dodecanol was used as an extractant, and a snipped pipette was used as an experimental vial to simplify the procedure of collecting and separating solidified extractant. The experimental parameters were optimized using a Plackett–Burman design and one‐factor‐at‐a‐time method. Under the optimal conditions in the water model, the limits of detection for analytes varied from 0.03 to 0.28 μg/L, and the enrichment factors ranged from 147 to 206. Linearity was achieved for diflubenzuron and flufenoxuron in a range of 0.5–500 μg/L, for hexaflumuron in a range of 1–500 μg/L, and for triflumuron in a range of 5–500 μg/L. The correlation coefficients for the analytes ranged from 0.9986 to 0.9994 with recoveries of 91.4–110.9%. Finally, the developed technique was successfully applied to fruit juice samples with acceptable results. The relative standard deviations of the analytes at two spiking levels (50 and 200 μg/L) varied between 0.2 and 4.5%.     

儿童额叶癫痫临床和长程视频脑电图特征

目的通过对46例儿童额叶癫痫患儿的临床表现、长程视频脑电图（VEEG）特点进行分析,提高对儿童额叶癫痫的认识。方法收集2008年12月至2014年8月儿科门诊及住院确诊的46例儿童额叶癫痫病例的资料,回顾性分析其临床表现、VEEG及神经影像学等特征。结果本组患儿发病年龄最小11个月,最大15岁。46例患儿共监测到临床发作258次,明确临床发作34例,14.7%仅于清醒期发作,61.8%仅在睡眠期发作,23.5%在清醒、睡眠中均有发作;临床发作形式包括额叶失神、局部阵挛发作、偏转性强直、姿势性强直、过度运动性自动症、口咽自动症、发声、发笑发作、临床下放电和自主神经性发作等。73.9%患儿记录到发作间期额叶为主的癫痫样放电,63.0%患儿记录到发作期额叶为主的癫痫样放电。结论儿童额叶癫痫临床发作频繁、短暂,以睡眠期发作为主,临床表现复杂多样,易漏诊;长程VEEG可监测到儿童额叶癫痫发作期临床及异常脑电图表现,可提供明确诊断率。     

肺炎支原体肺炎患儿急性期和恢复期血浆H-ficolin和L-ficolin水平分析

目的了解肺炎支原体肺炎患儿急性期和恢复期血浆中H-ficolin、L-ficolin水平的变化。方法采用ELISA法检测85例肺炎支原体肺炎患儿急性期和恢复期血浆H-ficolin、L-ficolin水平,并进行相关性分析。结果急性期H-ficolin水平1.8~25.2μg/ml,平均（11.9±5.9）μg/ml,恢复期H-ficolin水平0.3~26.5μg/ml,平均（10.1±5.7）μg/ml,急性期明显高于恢复期（Z=2.161,P=0.031）。急性期L-ficolin水平0.2~10.6μg/ml,平均（4.5±2.3）μg/ml,恢复期L-ficolin水平0.03~10.2μg/ml,平均（4.6±2.2）μg/ml,急性期和恢复期无统计学差异（t=0.245,P=0.807）。患儿急性期血浆H-ficolin水平与L-ficolin水平明显相关（r=0.22,P=0.039）。结论H-ficolin可能参与儿童肺炎支原体肺炎疾病过程。     

机械式毛竹镗簧机构的研制

<正>本文主要研究机构式毛竹镗簧刀体浮动机构。从研制的几种刀体浮动机构中,筛选出两种实践效果较好、性能优良、结构简单、成本较低的机构,并进行深入分析、论证、对比。     

大容重木材流送的技术问题

<正>大容重木材流送问题的实质是使它在流送全过程中保持必要的漂浮能力,这种漂浮能力可由木材的有效浮力和容许漂浮流送的时间来表示。文章列举了中同东北、西南、东南三大林区对一些有代表性的大容重树种木材所进行的流送前木材干燥和浸水试验的方法和测试结果,在分析成果的基础上,比较全面地提出了合理解决大容重木材流送的技术措施。     

94例发锌发钙值偏低患儿的临床主症分析与疗效观察

分析了９４例患儿头发微量元素含量。结果表明：患儿厌食、偏食、反复上呼吸道感染、多汗与体内微量元素与必需元素异常关系密切,特别是锌、钙缺乏更为明显。根据祖国医学“脾呼则口能知五味”、“肺主气属卫”的理论,采用针刺以疏通经络,调整脾胃功能,内服锌、钙制剂脉动这脾通便、补益肺气等中药治疗,治疗时间短,疗效提高,临床有效率达９０％以上。     

浮顶储罐在地震荷载作用下数值模拟分析

摘要：为了研究浮顶对储罐结构在动力荷载作用下地震响应的影响,选取2000方原油储罐为研究对象,分别建立无浮顶储罐及浮顶储罐的有限元分析模型,进行Ⅲ类场地单向地震激励作用下储罐结构的有限元数值模拟计算,对其在地震荷载作用下的基底剪力、倾覆力矩、晃动波高进行详细的对比。结果表明浮顶的存在对储罐的基底剪力和倾覆力矩产生影响甚微;对晃动波高有一定的抑制作用,2000方储罐波高降低率为41%。