Separation and purification of both tea seed polysaccharide and saponin from camellia cake extract using macroporous resin

A novel method to separate and purify tea seed polysaccharide and tea seed saponin from camellia cake extract by macroporous resin was developed. Among four kinds of resins (AB‐8, NKA‐9, XDA‐6, and D4020) tested, AB‐8 macroporous resin possessed optimal separating capacity for the two substances and thus was selected for the separation, in which deionized water was used to elute tea seed polysaccharide, 0.25% NaOH solution to remove the undesired pigments, and 90% ethanol to elute tea seed saponin. Further dynamic adsorption/desorption experiments on AB‐8 resin‐based column chromatography were conducted to obtain the optimal parameters. Under optimal dynamic adsorption and desorption conditions, 18.7 and 11.8% yield of tea seed polysaccharide and tea seed saponin were obtained with purities of 89.2 and 96.0%, respectively. The developed method provides a potential approach for the large‐scale production of tea seed polysaccharide and tea seed saponin from camellia cake.     

Assessment of the risk of infectious aerosols leaking to the environment from BSL-3 laboratory HEPA air filtration systems using model bacterial aerosols

To assess the risk of infectious bacterial aerosols leaking to the environment, the filtration efficiency of a biosafety level 3 （BSL-3） laboratory high-efficiency particulate （HEPA） filter was investigated using the aerosolized bacteria Serratia marcescens. The aerosol size was measured using an Andersen sampler. Eight first stage HEPA filters （numbered 1-87 were distributed in contaminated labs and exhausts from each of the first stage HEPA filters were aggregated and filtered through one second stage HEPA filter before being released to the environment. In total, 8 first-stage and I second-stage HEPA filters from the BSL-3 air purification system were analyzed. No S. marcescens was detected in first stage filters 1,2, 4, 5, 7 and 8 and the second stage HEPA filter. The filtration efficiencies against aerosolized S. marcescens were 〉99.9999%. First stage filter numbers 3 and 6 had filtration efficiencies of 99.9825% and 99.9906% respectively. When filter number 3 was replaced by a new filter and the bracket for filter number 6 was sealed, no aerosolized S. marcescens was detected in the filtered air. Our work suggests that the BSL-3 laboratory HEPA filter air purification system is effective against bacterial aerosols, with little to no bacterial leakage into the environment.     

纤锌矿GaN/ZnO 量子阱中的界面声子及其电声相互作用

根据介电连续模型和单轴晶体模型研究了纤锌矿量子阱中的界面声子模及其电声子相互作用的Fröhlich哈密顿。我们计算和讨论了纤锌矿GaN/ZnO单量子阱中的界面声子的色散关系和电声相互作用的耦合强度。色散曲线充分体现了纤锌矿晶体的各向异性;四支界面声子模出现在两个能量区域中,分别是：[ , ]和[ , ]。界面声子模出现消失的现象,光学声子模之间存在能量交迭区域。我们的结果也阐述了纤锌矿GaN/ZnO单量子阱中每支声子模与电子相互作用的对称性和耦合强度。     

Isothermal Melt Crystallization Kinetics for Poly(Trimethylene Terephthalate)/Poly(Butylene Terephthalate) Blends

The kinetics of isothermal melt crystallization of poly(trimethylene terephthalate) (PTT)/poly(butylene terephthalate) (PBT) blends were investigated using differential scanning calorimetry (DSC) over the crystallization temperature range of 184–192°C. Analysis of the data was carried out based on the Avrami equation. The values of the exponent found for all samples were between 2.0 and 3.0. The results indicated that the crystallization process tends to be two‐dimensional growth, which was consistent with the result of polarizing light microscopy (PLM). The activation energies were also determined by the Arrhenius equation for isothermal crystallization. The values of ΔE of PTT/PBT blends were greater than those for PTT and PBT. Lastly, using values of transport parameters common to many polymers (U*=6280 J/mol, T _∞=T _g – 30), together with experimentally determined values of T _m ⁰ and T _g, the nucleation parameter, K _g, for PTT, PBT, and PTT/PBT blends was estimated based on the Lauritzen–Hoffman theory.     

基于超声的单螺杆挤出机聚合物混合状态表征方法研究*

超声检测单螺杆挤出机中聚合物共混状态时,螺杆结构对回波信号幅值的衰减有很大影响,从而难以判别共混状态。本文分析了螺杆结构对超声回波信号的影响,以超声传播时间为依据,建立螺杆结构模型,根据螺棱位置的回波幅度,计算出低密度聚乙烯（LDPE）的衰减系数和不同螺杆位置的反射系数比,通过拟合建立反射系数比与螺杆结构关系模型;将上述模型应用到混合物中,计算不同位置的传感器采集信号的衰减系数方差并以此表征聚合物混合状态的均匀性。实验结果利用样本的电镜扫描图验证：上述建立模型及混合状态的表征方法可以较好地判别聚合物的共混状态。     

气相中2Ca＋介入N2O与CO, N2O与H2反应的计算研究

本文采用密度泛函理论DFT-UB3LYP方法, 在6-311+G(2d, p)的基组下, 计算研究了气相中Ca+离子介入N2O (1∑+)和CO (1∑+) 与N2O (1∑+) 和 H2 (1∑+g)反应的微观机理. 报道了二重态势能面上各反应物、中间体和过渡态的构型特征及能量, 并用频率分析和内禀反应坐标（IRC）方法对过渡态进行了验证. 计算结果表明,金属离子参与N2O和CO与N2O和H2的反应都分两步进行, 其中Ca+离子对反应N2O (X1∑+) + CO (1∑+)生成N2 (X1∑+g) + CO2 (1∑+g)比较Fe+, Ir+, Pt+等的金属离子有良好的催化作用, 而对反应N2O (X1∑+) + H2 (1∑+g) → N2 (1∑+g) + H2O (1A1) 催化作用不是很好,N2、CaOH+和H是该反应的主要产物,与实验观测结果相符, 并通过对金属离子亲氧性（OA）的计算, 从热力学方面进一步说明主题反应的可行性.     

超热电子的产生与输运背向辐射的实验研究

报道了在100TW fs激光器上采用电子磁谱仪和光学CCD积分成像相机分别对激光-固体靶相互作用在靶背方向产生的超热电子能谱及其光学渡越辐射进行的测量。能谱测量结果显示：超热电子能谱呈单温类-麦克斯韦分布,拟合的温度为107keV;光学渡越辐射(OTR)测量结果显示：OTR是由于超热电子输运穿越固体靶所致,而辐射区域呈圆盘状、有发散角、有光强分布;如果考虑超热电子的产生和加热机制,则占主导地位的加热机制是共振吸收对电子的加热。     

金属-有机骨架材料的合成及其在荧光传感器中的应用

金属-有机框架材料（MOFs）,是一类由金属节点或者是次级构筑单元与有机配体通过配位键自主装形成的材料。由于其丰富的拓扑结构及在多领域的潜在应用,已被广泛研究。最近关于块状和纳米颗粒形式的发光MOFs 的研究表明,这些材料具有优异的发光性质,可用来检测识别溶剂分子、重金属离子、黄曲霉素、硝基苯类爆炸物以及碘离子等。并且开发高灵敏度,高选择性,快速响应和完全可逆的有毒物质和爆炸物检测传感器,在国土安全,环境安全及其他人道主义关切问题上有着极大的需求。在这篇文章中,我们主要讨论MOF材料作为荧光传感器的应用研究和发展前景。     

2-巯基苯并咪唑衍生物的设计、合成及抗肿瘤活性研究

为了从苯并咪唑类衍生物中寻找新的活性化合物,以溴乙酸作为起始原料,设计合成了17个2-巯基苯并咪唑衍生物4a～4q。采用噻唑蓝(MTT)法测试了目标化合物对人宫颈癌细胞(He La)、人乳腺癌细胞(MCF-7)、人肝癌细胞(HepG2)、人非小细胞肺癌细胞(A549)的增殖抑制活性。结果显示,大部分化合物具有较好的抗肿瘤活性,其中,((1H-苯并[d]咪唑-2-基)硫基)-1-(4-二苯甲基哌嗪-1-基)乙烷-1-酮(4l)对HepG2细胞的抑制活性最好,IC_(50)值为12. 62±0. 78μmol/L,接近于对照药品吉非替尼(9. 72±0. 38μmol/L)。此外,利用分子对接方法对目标化合物的构效关系进行了讨论。     

L波段高功率多注速调管设计与模拟

 开展了峰值功率10 MW、平均功率150kW的L波段多注速调管的研究工作。采用均匀场多透镜聚焦系统对多电子注进行聚焦,获得了具有良好层流性和波动性的旁轴多注电子光学系统;采用二次谐波腔,对6个电子注、6个同轴谐振腔结构的速调管进行了注波互作用计算。结果表明,当电子注电压为115 kV,电流为132 A时,可获得大于10 MW的脉冲输出功率,大于65%的输出效率和大于45 dB的增益。