琥珀酸十八酯晶体过饱和溶液的成核研究

研究了琥珀酸十八酯（ＯＳＯ）晶体过饱和溶液的成核过程，测量了以诱导期表示的成核速率，讨论了温度、过饱和度和溶剂对成核速率的影响。ＯＳＯ过饱和溶液的成核速率随着温度的升高和过饱和度的增大而增大，溶剂不同其数值也不同，实验结果根据经典成核理论进行了分析。     

流态化CVD制备超细Al_2O_3－SnO_2复合粒子过程模型研究

基于流态化ＣＶＤ制备超细复合粒子过程中的反应、成核、包敷、气流夹带，建立了流态化ＣＶＤ反应器中描述超细粒子的粒度、分布及成核包敷、成膜包敷的一维过程模型。针对ＳｎＣｌ＿４－Ｈ＿２Ｏ－Ｎ＿２体系包敷超细Ａｌ＿２Ｏ＿３粒子的过程，研究了反应器中ＳｎＯ＿２粒子的形成过程及操作参数对其在Ａｌ＿２Ｏ＿３粒子表面的淀积速率及形态的影响。结果表明，反应温度和ＳｎＣｌ＿４浓度升高，包敷速率加快，包敷形态变差；背景气氛粘度增大，包敷形态变优，包敷速率减小；操作气速增大，包敷速率加快，包敷形态变优。     

马来酸氢十八酯过饱和溶液的成核研究

研究马来酸氢十八酯（ＯＨＭ）过饱和溶液的成核过程,测量以诱导时间表示的成核速率,讨论温度、过饱和比和溶剂对成核速率的影响,根据经典均匀成核理论计算了晶体的固－液表面张力、成核自由能和临界成核半径．结果表明,ＯＨＭ晶体过饱和溶液的成核速率随着温度和过饱和度的提高而增大,不同的溶剂有不同的数值．     

纺锤形铁黄α－FeOOH微晶合成动力学研究

本文对纺锤形α－ＦｅＯＯＨ微晶合成动力学过程进行了研究．利用复相反应经验动力学方程，考察了初始浓度、反应温度和空气流量对Ｆｅ（ＯＨ）２－ＰｅＣＯ３悬浮液氧化速率的影响，确定了α－ＦｅＯＯＨ成核－生长速率方程，证实了晶粒生长阶段存在溶解－氧化的动态平衡，根据活化能大小，推断相界面氧化反应为该复相反应的控制步骤，还对α－ＦｅＯＯＨ成核生长微观机理作了初步探讨．     

纺锤形铁黄α—FeOOH微晶合成动力学研究

本文对纺锤形α－ＦｅＯＯＨ微晶合成动力学过程进行了研究，利用复相反应经验动力学方程，考察了初始浓度，反应温度和空气流量对Ｆｅ（ＯＨ）２－ＦｅＣＯ３悬浮液氧化速率的影响，确定了α－ＦｅＯＯＨ成核－生长速率方程，证实了晶粒生长阶段存在溶解－氧化的动态平衡，根据活化能大小，推断相界面氧化反应为该相反应的控制步骤，还对α－ＦｅＯＯＨ成核生长微观机理作了初步探讨。     

用TEOSPECVD氧化硅做掩蔽层选择性生长金刚石薄膜

本文研究了在ＨＦ—ＣＶＤ法中，衬底温度Ｔｓ对ＰＥＴＥＯＳ（等离子体增强正硅酸乙酯）氧化硅—硅衬底上选择性生长金刚石薄膜的影响。结果表明：Ｔｓ变化影响ＰＥＴＥＯＳ氧化硅掩蔽层区域和硅表面金刚石晶粒成核密度。Ｔｓ较低时（７５０—８２０℃），ＰＥＴＥＯＳ氧化硅区域成核密度远小于裸露硅表面；随Ｔｓ升高（＞８２０℃），氧化硅区域成核密度增加很快；当Ｔｓ＞８５０℃时，氧化硅区域成核密度超过硅表面。     

单分散二氧化硅体系制备中正硅酸乙酯水解与成核及颗粒生长的关系

用透射电镜对乙醇介质中氨催化下正硅酸乙酯（ＴＥＯＳ）水解制各单分散二氧化硅微粒过程中颗粒的生长过程进行了跟踪，通过对ＴＥＯＳ的水解速率与成核及颗粒生长速率间关系的研究，发现水解是整个反应的控制步骤，影响水解的因素也同样影响成核及颗粒的生长。     

单分散二氧化硅体系制备中正硅酸乙酯水解与成核及颗粒生长的关系

用透射电镜对乙醇介质中氨催化下正硅酸乙酯（ＴＥＯＳ）水解制备单分散二氧化硅微粒过程中颗粒的生长过程进行了跟踪，通过对ＴＥＯＳ的水解速率与成核及颗粒生长速率间关系的研究，发现水解是整个反应的控制步骤，影响水解的因素也同样影响成核及颗粒的生长。     

30℃时K2SO4和（NH4）2SO4在CH3OH—H2O溶液中的共饱和度研究

本研究测定了３０℃时Ｋ２ＳＯ４－（ＮＨ４）２ＳＯ４－ＣＨ３ＯＨ－Ｈ２Ｏ元体系的共饱和度，分析了ＣＨ３ＯＨ含量对Ｋ２ＳＯ４及（ＮＨ４）２ＳＯ４共饱和度的影响，得出了以ＣＨ３ＯＨ为盐析剂，从Ｋ２ＳＯ４和（ＮＨ４）２ＳＯ４的水溶液中晶析Ｋ２ＳＯ４的规律，为Ｋ２ＳＯ４和（ＮＨ４）２ＳＯ４的分离提供理论依据。     

湿法烟气脱硫的理论和实验研究(Ⅱ)--湿壁塔烟气脱硫数学模型

以中试湿壁塔为基础,一个通用型湿法烟气脱硫（ＷＦＧＤ）模型被发展。该模型包含一个总反应器模型和４个速率控制步骤,即ＳＯ２的吸收、ＨＳＯ－３的氧化、石灰石的溶解和石膏的结晶。ＷＦＧＤ中所有重要的组分：ＳＯ２（ｇ）、ＳＯ２（ａｑ）、ＨＳＯ－３、ＳＯ２－３、ＨＳＯ－４、ＳＯ２－４、ＣＯ２（ｇ）、ＣＯ２（ａｑ）、ＨＣＯ－３、ＣＯ２－３、Ｃａ２＋、ＣａＣＯ３（ｓ）、Ｍｇ２＋、Ｏ２（ｇ）、Ｏ２（ａｑ）、ＣａＳＯ４·２Ｈ２Ｏ、Ｈ２Ｏ、Ｈ＋和ＯＨ－均在模型中被考虑。该建模方法可应用于其它类型湿法烟气脱硫装置的设计中。     

超软X射线分光晶体OHS溶液性质的研究

较系统地观察研究了ＯＨＳ晶体在各种有机溶剂中自发结晶的规律和结晶习性，测定了ＯＨＳ在苯和甲苯中的溶解度曲线和介稳区宽度。提出了单晶生长较合适的溶剂和生长温度区间，对溶液的状态进行了讨论。     

肥胖低通气综合征患者血清瘦素水平的变化及意义

为了研究血清瘦素在肥胖低通气综合征(OHS)患者体内的变化及其意义,通过酶联免疫吸附测定(ELISA)法测定了所有受试者的血清瘦素水平,选取OHS组23例、肥胖OSA组40例、非肥胖OSA组14例、单纯肥胖组6例和正常对照组10例。比较所有受试者的一般资料、血清瘦素水平和多导睡眠参数,分析肥胖各组的血气分析结果。对瘦素与其他参数进行相关性分析,并分析其对OHS的诊断预测。结果表明OHS组BMI、颈围明显高于其他组。OHS组血清瘦素水平高于其他各组,且各组之间均存在明显差异(P 0.05)。血清瘦素水平与BMI、颈围、腰围、臀围、Pa CO_2、动脉血HCO_3~-呈正相关,与Pa O_2呈负相关。BMI、颈围、腰围和血清瘦素水平对OHS具有诊断预测作用。可见OHS组血清瘦素水平较肥胖OSA组、单纯肥胖组明显升高,除了肥胖因素外,OHS本身也可成为血清瘦素水平升高的原因,血清瘦素水平的升高可以作为OHS的诊断预测指标之一。     

职业健康安全目标的探讨

对如何建立职业健康安全目标进行了分析，表述了应在哪些职能和层次上制定职业健康安全目标，制定目标的作用和依据以及持续改进的要求，为组织制定职业健康安全目标提供了指导。     

Prediction of absolute crystal-nucleation rate in hard-sphere colloids

Crystal nucleation is a much-studied phenomenon, yet the rate at which it occurs remains difficult to predict. Small crystal nuclei form spontaneously in supersaturated solutions, but unless their size exceeds a critical value--the so-called critical nucleus--they will re-dissolve rather than grow. It is this rate-limiting step that has proved difficult to probe experimentally. The crystal nucleation rate depends on Pcrit, the (very small) probability that a critical nucleus forms spontaneously, and on a kinetic factor (kappa) that measures the rate at which critical nuclei subsequently grow. Given the absence of a priori knowledge of either quantity, classical nucleation theory is commonly used to analyse crystal nucleation experiments, with the unconstrained parameters adjusted to fit the observations. This approach yields no 'first principles' prediction of absolute nucleation rates. Here we approach the problem from a different angle, simulating the nucleation process in a suspension of hard colloidal spheres, to obtain quantitative numerical predictions of the crystal nucleation rate. We find large discrepancies between the computed nucleation rates and those deduced from experiments: the best experimental estimates of Pcrit seem to be too large by several orders of magnitude.     

氧化催化转化器对柴油机颗粒物排放特性的影响

以某高压共轨重型柴油机为样机,研究氧化催化转化器(Diesel Oxidation Catalyst,DOC)对柴油机颗粒排放规律的影响.研究结果表明,各工况下,DOC后测点颗粒物质量浓度相对于前测点均有所下降,降幅随转速升高而减小,随着负荷的增大变化不大;外特性下,DOC对总颗粒、核态颗粒和聚集态颗粒的转化率均随着转速增加而波动下降,其平均转化率分别为21.5%,26.2%和15.4%;最大转矩转速1 400r·min-1负荷特性下,DOC对总颗粒、核态颗粒、聚集态颗粒的转化率均随着负荷的增大先下降再上升,其平均转化率为34.6%,38.8%和27.3%;DOC对核态颗粒物的转化率高于聚集态颗粒物,在粒径为9~12nm的范围内转化率达到最高,其他粒径范围内转化率大多介于20%~40%之间.     

Stable sulphate clusters as a source of new atmospheric particles

The formation of new atmospheric particles with diameters of 3-10 nm has been observed at a variety of altitudes and locations. Such aerosol particles have the potential to grow into cloud condensation nuclei, thus affecting cloud formation as well as the global radiation budget. In some cases, the observed formation rates of new particles have been adequately explained by binary nucleation, involving water and sulphuric acid, but in certain locations--particularly those within the marine boundary layer and at continental sites--observed ambient nucleation rates exceed those predicted by the binary scheme. In these locations, ambient sulphuric acid (H2SO4) levels are typically lower than required for binary nucleation, but are sufficient for ternary nucleation (sulphuric acid-ammonia-water). Here we present results from an aerosol dynamics model with a ternary nucleation scheme which indicate that nucleation in the troposphere should be ubiquitous, and yield a reservoir of thermodynamically stable clusters 1-3 nm in size. We suggest that the growth of these clusters to a detectable size (> 3 nm particle diameter) is restricted by the availability of condensable vapour. Observations of atmospheric particle formation and growth from a continental and a coastal site support this hypothesis, indicating that a growth process including ternary nucleation is likely to be responsible for the formation of cloud condensation nuclei.     

Direct observation of individual RecA filaments assembling on single DNA molecules

Escherichia coli RecA is essential for the repair of DNA double-strand breaks by homologous recombination. Repair requires the formation of a RecA nucleoprotein filament. Previous studies have indicated a mechanism of filament assembly whereby slow nucleation of RecA protein on DNA is followed by rapid growth. However, many aspects of this process remain unclear, including the rates of nucleation and growth and the involvement of ATP hydrolysis, largely because visualization at the single-filament level is lacking. Here we report the direct observation of filament assembly on individual double-stranded DNA molecules using fluorescently modified RecA. The nucleoprotein filaments saturate the DNA and extend it approximately 1.6-fold. At early time points, discrete RecA clusters are seen, permitting analysis of single-filament growth from individual nuclei. Formation of nascent RecA filaments is independent of ATP hydrolysis but is dependent on the type of nucleotide cofactor and the RecA concentration, suggesting that nucleation involves binding of approximately 4-5 ATP-RecA monomers to DNA. Individual RecA filaments grow at rates of 3-10 nm s(-1). Growth is bidirectional and, in contrast to nucleation, independent of nucleotide cofactor, suggesting addition of approximately 2-7 monomers s(-1). These results are in accord with extensive genetic and biochemical studies, and indicate that assembly in vivo is controlled at the nucleation step. We anticipate that our approach and conclusions can be extended to the related eukaryotic counterpart, Rad51 (see ref.), and to regulation by assembly mediators.