Synthesis and physicochemical characterization of amphiphilic block copolymer self‐aggregates formed by poly(ethylene glycol)‐block‐poly(ϵ‐caprolactone)

Diblock copolymers with different poly(ε‐caprolactone) (PCL) block lengths were synthesized by ring‐opening polymerization of ε‐caprolactone in the presence of monomethoxy poly(ethylene glycol) (mPEG‐OH, MW 2000) as initiator. The self‐aggregation behaviors and microscopic characteristics of the diblock copolymer self‐aggregates, prepared by the diafiltration method, were investigated by using ¹H NMR, dynamic light scattering (DLS), and fluorescence spectroscopy. The PEG–PCL block copolymers formed the self‐aggregate in an aqueous environment by intra‐ and/or intermolecular association between hydrophobic PCL chains. The critical aggregation concentrations of the block copolymer self‐aggregate became lower with increasing hydrophobic PCL block length. On the other hand, reverse trends of mean hydrodynamic diameters were measured by DLS owing to the increasing bulkiness of the hydrophobic chains and hydrophobic interaction between the PCL microdomains. The partition equilibrium constants (K_v) of pyrene, measured by fluorescence spectroscopy, revealed that the inner core hydrophobicity of the nanoparticles increased with increasing PCL chain length. The aggregation number of PCL chain per one hydrophobic microdomain, investigated by the fluorescence quenching method using cetylpyridinium chloride as a quencher, revealed that 4–20 block copolymer chains were needed to form a hydrophobic microdomain, depending on PCL block length. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3520–3527, 2006     

Pervaporation study of water and tert‐butanol mixtures

The permeation behavior of water/tert‐butanol mixture through Sulzer Pervap2510 hydrophilic poly(vinyl alcohol) membranes was investigated and the effects of feed composition and temperature on separation efficiency of the membranes were studied. The pervaporation experiments were carried out with feed water content varying from 0 to 20 wt % according to the existing industrial needs and with the feed temperature from 60 to 100°C. Over this range, both water flux and separation factor increased with increasing water content and feed temperature. These phenomena may be attributed to (1) the strong interaction between water and the membrane, (2) the decoupling effect of the permeants and the membrane at elevated temperatures, and (3) the steric hindrance effect of branch chain alcohol. The permeability ratio (the ideal separation factor) of water to tert‐butanol across the membrane was calculated and found to follow the same relationship with increasing temperature and water content. Both flux and separation factor obtained from the Pervap2510 membrane in this study were much higher than previous reported values, possible causes for which were analyzed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 4082–4090, 2004     

气体作冷却润滑剂的绿色切削试验

为实现绿色切削,研究了无污染、无危害的冷却润滑技术.采用氮气、氧气、二氧化碳气、氩气及过热水蒸气作冷却润滑剂,进行了单因素切削试验.试验结果表明,这些气体冷却润滑剂可以减小切削变形、切削力,降低切削温度,改善加工表面形貌.根据试验结果和冷却润滑作用机理分析可知,气体在切削中具有一定的冷却润滑作用,同时具有来源广泛、无毒害和污染、不用回收处理等绿色特点,故气体具备绿色切削的潜力.     

SAPMAC法蓝宝石单晶的生长、检测与超声震动加工

分析SAPMAC法生长大尺寸蓝宝石晶体的工艺技术,并对制备的晶体质量进行了检测与分析.研究结果表明:采用SAPMAC法生长的蓝宝石晶体结构完整,FHWM值很小,只有11arcsec;缺陷密度在102/cm2水平,纯度高于99.995%,常温下晶体在3～5μm波段红外透过率高于85%;用超声振动加工技术对大尺寸蓝宝石单晶进行加工,设计了专用金刚石磨削复合刀具,提高了加工效率.     

情绪智力对高校教师的多层次影响实证研究

研究采用多层次数据统计软件,探讨情绪智力对高校教师职业成长、教学方式与教学质量的影响关系。采用跨层次分析468份问卷后发现:教师情绪智力对学生课程认同与教师认同具有正向影响,这种影响是通过教师情绪智力改变教师职业成长与教学方式的机制加以传导。通过上述实证检验,阐述了当前教师情绪智力对高校教学质量影响的重要作用,建议高校在教师选拔与培养的过程中不仅需要关注其科研水平的提升,也应当关注其情绪智力的培养,从而提高整体教学质量。     

基于机械臂运动的组合航天器惯性参数在轨辨识

随着空间技术发展,交会对接任务越来越多,服务航天器与目标航天器对接形成组合航天器后惯性参数会发生明显变化。因此,提出一种基于机械臂运动的组合航天器惯性参数在轨辨识方法。该方法可以分为2步:第一步辨识组合航天器的质量和质心;第二步辨识组合航天器的惯性张量。该方法优点是实现了质量、质心与惯性张量等辨识参数的相互解耦,不需要消耗航天器上宝贵的喷气燃料,仅需要测量航天器的速度,而不是加速度和力。仿真结果验证了方法的有效性。     

注气井井筒结垢预测研究

在油田开发过程中,油、气、水和泥浆在地层或管道中流动,当达到一定条件时,油垢、水垢或泥垢便会产生。在实际生产过程中,油垢和泥垢通常伴随着水垢而生成,所以对水垢结垢趋势的预测研究显得至关重要。介绍了Oddo-Tomos饱和指数法的理论预测模型,以及在生产过程中利用Oddo-Tomos饱和指数法预测油田结垢趋势的方法,阐述并分析了油田结垢对油田开采的影响。研究结果可为下一步的生产作业提供理论依据。     

注气井井筒结垢预测研究

在油田开发过程中,油、气、水和泥浆在地层或管道中流动,当达到一定条件时,油垢、水垢或泥垢便会产生。在实际生产过程中,油垢和泥垢通常伴随着水垢而生成,所以对水垢结垢趋势的预测研究显得至关重要。介绍了Oddo-Tomos饱和指数法的理论预测模型,以及在生产过程中利用Oddo-Tomos饱和指数法预测油田结垢趋势的方法,阐述并分析了油田结垢对油田开采的影响。研究结果可为下一步的生产作业提供理论依据。     

18650磷酸铁锂电池不同放电倍率下产热机理研究

利用多物理场耦合软件COMSOL-Multiphisics建立了二维轴对称电化学-热耦合模型.探究了不同倍率放电下18650磷酸铁锂电池电极区域和隔膜区域的产热情况,并根据不同区域的热量积累,进一步分析了放电倍率的增加对反应热、欧姆热以及极化热等不同类型产热的影响.结果表明:随着放电倍率的增加,产热区域主要以正极产热和隔膜产热为主,产热类型主要以欧姆热为主,3 C放电时欧姆热占总产热的72.43％,反应热和极化热相对占比较小.