Frequency tunable single-line pulsed first-overtone carbon monoxide laser

Tunable single-line first-overtone (FO) CO lasing on wavelengths from 2.7 up to 4.2 μm corresponding to overtone vibrational transitions from 13→11 up to 38→36 on 413 ro-vibrational lines was experimentally obtained. A parametric study of energetic and spectral characteristics of the single-line FO CO laser was carried out. Energy distribution over ro-vibrational lines was measured. The maximum specific output energy (SOE) came up to 3 J/l Amagat, with single-line output efficiency being up to 0.6%. For the first time, a multi-quantum theoretical model was used to describe the tunable single-line FO CO laser. This multi-quantum approach demonstrated better agreement between theoretical calculations and observed experimental data for laser output as a function of vibrational quantum numbers.     

电子的交换作用对激发态能量的影响

根据作者提出的物理模型和简洁有效的计算方法,考虑电子交换应对于激发态的影响,计算了激发态Ｌｉ原子（１ｓ＾２４ｓ）＾２Ｓ１／２的能量。计算结果表明：电子的交换能对低激发态的贡献较大,而对较高激发态（５ｓ、６ｓ…以上）在计算过程中可以忽略不计。     

Synthesis and structural studies of <Emphasis Type="Italic">tris</Emphasis>-2-chlorobenzylamine and <Emphasis Type="Italic">tris</Emphasis>-2-bromobenzylamine

The tris-2-chloro and 2-bromotribenzylamines are prepared from aqueous ammonia and 2-chlorobenzyl chloride and 2-bromobenzyl bromide, respectively, in ethanol. Recrystallization yielded colorless cubes of each product. The crystal structures are each solved in space group P , and are isostructural. The tris-2-chloro compound, 1, has a = 7.4226(5) Å, b = 9.0825(7) Å, c = 14.529(1) Å, = 78.279(1), = 82.389(1), = 84.661(1), and V = 948.41(12) ų with Z = 2, and d_calc = 1.368 Mg/m³. The tris-2-bromo analog, 2, has a = 7.6569(11) Å, b = 9.0922(13) Å, c = 14.614(2) Å, = 79.286(2), = 81.777(2), = 85.401(2), and V = 987.9(2) ų with Z = 2, and d_calc = 1.762 Mg/m³. Lithium–halogen exchange experiments conducted in tetrahydrofuran at –78C using n-butyl lithium revealed that no exchange occurred for the tris-2-chloro compound, but did occur for the tris-2-bromo analog to yield tribenzylamine upon quench and work-up.     

冠状毛细血管长度非线性变化及渗透作用下的毛细血管血液流动

建立冠状毛细血管内血流的血液动力学模型,研究毛细血管长度沿轴向的非线性变化及冠状毛细血管与周围组织的渗透和物质交换对血液流动的影响。考虑单根长弹性并具有通透性的冠状毛细血管,毛细血管长度非线性变化,毛细血管内血液为粘性不可压缩牛顿流体,跨壁滤过遵循Starling定律,血浆胶体渗透压和血浆蛋白浓度成线性关系。建立血管半径的无量纲方程,数值求解不同生理参数情况下,左心室壁不同层中毛细血管沿长度平均的无量纲半径和不同层毛细血管的平均流量。结果显示,冠状毛细血管与周围组织的渗透和物质交换及毛细血管长度沿轴向的非线性变化对平均无量纲半径和平均出口流量几乎没有影响;而对弹性模量较小的毛细血管,则对心脏收缩期时的平均进口流量有不同程度的影响。     

Synthesis of highly sulfonated poly(arylene ether sulfone) random (statistical) copolymers via direct polymerization

Novel biphenol‐based wholly aromatic poly (arylene ether sulfones) containing pendant sulfonate groups were prepared by direct aromatic nucleophilic substitution polycondensation of disodium 3,3′‐disulfonate‐4,4′‐dichlorodiphenyl sulfone (SDCDPS), 4,4′‐dichlorodiphenylsulfone (DCDPS) and biphenol. Copolymerization proceeded quantitatively to high molecular weight in N‐methyl‐2‐pyrrolidinone at 190°C in the presence of anhydrous potassium carbonate. Tough membranes were successfully cast from the control and the copolymers, which had a SDCDPS/DCDPS mole ratio of either 40:60 or 60:40 using N,N‐dimethylactamide; the 100% SDCDPS homopolymer was water soluble. Short‐term aging (30 min) indicates that the desired acid form membranes are stable to 220°C in air and conductivity values at 25°C of 0.110 (40%) and 0.170 S/cm (60%) were measured, which are comparable to or higher than the state‐of‐the art fluorinated copolymer Nafion 1135 control. The new copolymers, which contain ion conductivity sites on deactivated rings, are candidates as new polymeric electrolyte materials for proton exchange membrane (PEM) fuel cells. Further research comparing their membrane behavior to post‐sulfonated systems is in progress.     

二硫化钼改性热塑性聚酰亚胺复合材料的摩擦磨损性能研究

采用热压成型工艺制备MoS2 填充热塑性聚酰亚胺复合材料,测定了其弯曲强度和压缩强度,采用MPX-2000型摩擦磨损试验机评价MoS2 填充热塑性聚酰亚胺复合材料在干摩擦和水润滑2种工况下的摩擦磨损性能,利用扫描电子显微镜观察和分析材料磨损表面形貌和元素分布.结果表明:与聚酰亚胺树脂相比,加入MoS2后复合材料的弯曲强度和压缩强度有所降低,随着MoS2含量增加,材料的弯曲强度和压缩强度趋于稳定;在干摩擦条件下,MoS2逐步在磨损表面富集,相应的摩擦系数有所降低;MoS2含量为10%时磨损表面仅出现局部熔融,磨损率最低,当MoS2含量为20%时磨损表面出现深度熔融,磨损率较大;在水润滑条件下,MoS2仍起到良好的润滑作用,摩损率较干摩擦条件下降低1个数量级,表现出疲劳磨损特征.     

强碱阴离子交换树脂合成及热稳定性能研究

氯甲基化聚苯乙烯树脂与不同的叔胺反应制备了含不同季铵基团的强碱树脂.将氯甲基化聚苯乙烯树脂进行硝化、溴化反应后,再用三甲胺进行季铵化制备了苯环上含有吸电子基团的强碱树脂,测定了所制备树脂在水中的热稳定性.结果表明,位阻较大的季铵表现出较高的热稳定性;硝化、溴化后的树脂热稳定性有一定改善;而热重分析表明苯环上引入吸电子取代基不利于提高碱基在高温下的稳定性.     

离子交换法处理曝气后氯化亚铜的废水研究

通过预曝气的方法,氯化亚铜废水溶液中Cu(Ⅰ)被氧化为Cu(Ⅱ),并能简化氯化亚铜废水溶液的粒子结构,分别采用201×7 OH-型强碱性阴离子树脂和732 Na型强酸性阳离子树脂处理曝气后的氯化亚铜废水,进行了曝气时间、pH值和温度等因素对废水处理效果的研究,得到最佳的处理废水条件。曝气180 min后,在温度60 ℃,V溶液/V树脂=2/1,阳离子交换反应15 min时,可使废水溶液中铜粒子浓度达到国家废水一级排放标准。     

几种乙酸铵离心法测定土壤阳离子交换量的方法探讨

乙酸铵离心交换法测定酸性和中性土壤阳离子交换量是经典方法,但此方法的蒸馏过程繁琐、时间长、效率低。本文引用纳氏试剂分光光度法测定土壤CEC值,并将结果与乙酸铵离心法常用的几种传统测定方法进行了实验对比和总结。通过对国家标准样品及实际土壤样品的CEC值测定,纳氏试剂比色法的精密度在2-4%之间,准确度与经典方法一致。与传统滴定法比较,取代了蒸馏的步骤,测定方法简单,干扰少,结果可靠,可操作性强。     

Morphology and glass transition behavior of polycarbonate–phenoxy system: Effects of trans-reactions in domain interface regions

Effects of trans reactions on the morphology, glass transition, and phase behavior in a classical blend system of a poly(hydroxyl ether bisphenol-A) (phenoxy) with bisphenol-A polycarbonate (PC) were investigated by differential scanning calorimetry (DSC) and optical microscopy. Although two T_gs were observed in the as-prepared PC/phenoxy blends, an apparently single, but broadened, T_g was found in the blends after heating at high temperatures, typically 200–250°C for short times. The optical microscopy results indicated that same scales of heterogeneity did exist in post-heated PC/phenoxy blends as well as unheated blends. Explanations were provided. After heating-induced interchange reactions ( OH and carbonate), randomly linked polymer chains might form at the numerous interfaces of the mutually occluded/included micro-domains. The majority of the chains in the micro-domains are forced to relax in coordinated motion modes after heating, thus showing a single T_g. A mechanism of trans reactions in interfacial regions was briefly discussed in supplement to earlier reports in the literature. © 1997 John Wiley & Sons, Inc.