一种可视化检测肼的苯并噁唑类荧光增强型探针

以苯并噁唑为荧光基团，合成和表征了一种用于可视化检测N₂H₄的荧光增强型探针(HL2)，并研究了其光谱性质。实验结果表明，HL2对N₂H₄具有高的选择性和灵敏度，抗干扰能力强，响应快，它对N₂H₄的检测限为0.072 μmol·L^-1。此外，HL2可应用于实际水体样品中N₂H₄的检测，并且还能实现HeLa细胞中N₂H₄的荧光成像。     

Microstructure evolution of laser solid forming of Ti-Al-V ternary system alloys from blended elemental powders

Morphology evolution of prior β grains of laser solid forming (LSF) Ti-xAl-yV (x 11,y 20) alloys from blended elemental powders is investigated. The formation mechanism of grain morphology is revealed by incorporating columnar to equiaxed transition (CET) mechanism during solidification. The morphology of prior β grains of LSF Ti-6Al-yV changes from columnar to equiaxed grains with increasing element V content from 4 to 20 wt.-%. This agrees well with CET theoretical prediction. Likewise, the grain morphology of LSF Ti-xAl-2V from blended elemental powders changes from large columnar to small equiaxed with increasing Al content from 2 to 11 wt.-%. The macro-morphologies of LSF Ti-8Al-2V and Ti-11Al-2V from blended elemental powders do not agree with CET predictions. This is caused by the increased disturbance effects of mixing enthalpy with increasing Al content, generated in the alloying process of Ti, Al, and V in the molten pool.     

Effect of solution temperature and cooling rate on microstructure and mechanical properties of laser solid forming Ti-6Al-4V alloy

The effect of solution temperature and cooling rate on microstructure and mechanical properties of laser solid forming (LSF) Ti-6Al-4V alloy is investigated.The samples are solutions treated at 900,950,and 1000°C,followed by water quenching,air cooling,and furnace cooling,respectively.It is found that the cooling rate of solution treatment has a more important effect on the microstructure in comparison with the solution temperature.The martensite α'formed during water quenching results in the higher hardnes...     

The effect of interfacial energy anisotropy on planar interface instability in a succinonitrile alloy under a small temperature gradient

The morphological stability of a planar interface with different crystallographic orientations is studied under a small positive temperature gradient using a transparent model alloy of succinonitrile.Novel experimental apparatus is constructed to provide a temperature gradient of about 0.37 K/mm.Under this small temperature gradient,the planar interface instability depends largely on the crystallographic orientation.It is shown experimentally that the effect of interfacial energy anisotropy on planar interface stability cannot be neglected even in a small temperature gradient system.Higher interfacial energy anisotropy leads the planar interface to become more unstable,which is different from the stabilizing effect of the interfacial energy on the planar interface.The experimental results are in agreement with previous theoretical calculations and phase field simulations.     

GaSb单晶空间生长

空间的微重力给晶体生长提供了一个消除自然对流、由纯扩散控制的生长环境,为提高晶体质量创造了条件,引起晶体生长研究人员的关注.中国科学院物理研究所和日本东京大学电子工程系合作,1992年在中国第14颗返回式卫星上成功地生长了一根φ6 mm×30 mm外形完整的GaSb单晶.对空间生长的晶体的研究显示：晶体在空间生长部分无Ⅰ类生长条纹,表明晶体生长时既无自然对流也没有Marangoni对流.位错密度测定表明,晶体在空间生长期间熔体未与坩埚器壁接触时生长的晶体位错密度接近于零,而熔体与坩埚器壁接触后位错密度迅速增高.详细叙述了该晶体的生长和研究,分析了微重力对晶体生长的影响,并对空间晶体生长的发展提出看法.     

Cu固液界面能的分子动力学计算

本文使用分子动力学方法对液相Cu中不同半径晶胚的生长和熔化行为进行了研究. 随着半径的增加, 晶胚生长的临界温度升高. 临界形核过冷度和晶胚半径倒数成正比关系, 这和经典形核理论一致. 由上述关系计算得到Cu的Gibbs-Thomson系数为1.12×10^-7 K·m, Cu的固液界面能为0.146 J/m², Cu的Turnbull系数为0.416, 这些计算值均与实验值一致. 关键词： 分子动力学 经典形核理论 固液界面能     

高分子-镍络合物在硝基化合物及醛酮类加氢反应中的催化活性

本工作制备了数种高分子-镍(Ⅱ)配合物并用NaBH_4、LiAlH_4、甲醛氨水溶液或分子氢使之还原。研究结果表明,高分子—镍(Ⅱ)配合物难以用LiAlH_4或甲醛还原,而用氢气或NaBH_4还原后的配合物在较高温度(100～120℃)及一定的压力(3～6MPa)下还原硝基化合物及醛、酮类化合物时具有一定的催化活性,其中以NaBH_4还原的配合物活性最高。硝基化合物被还原为相应的胺,无副产物,醛、酮类还原为相应的醇,未发现氢解产物,说明催化剂有较高的选择性。此外还研究了腈类的加氢反应。     

可酶降解的温度及pH敏感水凝胶的制备及对牛血清白蛋白的吸附和释放

以4,4'-二甲基丙烯酰氨基偶氮苯(BMAAB)为偶氮交联剂,制备了可酶降解的N-异丙基丙烯酰胺(NIPAAm)-丙烯酸(AA)共聚物水凝胶. 结果表明,研究的凝胶均表现出在4 ℃和37 ℃之间的溶胀相转变. 以牛血清白蛋白(BSA)为模型药物,在pH=7.4的缓冲溶液中对BSA进行了负载. 结果表明,凝胶在4 ℃时对BSA的负载量为144.5 mg(BSA)/g(gel),37 ℃为14.8 mg(BSA)/g(gel). 凝胶在pH=7.4的缓冲溶液中,在结肠菌作用下能发生酶降解,药物累积释放量4 d可达100 mg(BSA)/g干胶.     

二苯甲酮晶体的过冷熔体生长及性能

本文采用过冷熔体法进行二苯甲酮晶体的生长实验,得到尺寸约为30mm×40mm×60mm的单晶.测定了单晶的光谱透射率、折射率及SHG系数,并与溶液法生长的结果进行比较,发现过冷熔体法生长的二苯甲酮单晶在近紫外到近红外波段具有更为优异的光学特性,适合用作YAG激光倍频晶体,也可用作黄绿波段激光调制器.     

二苯甲酮晶体的生长习性预测和实验研究

从生长速度恒定的三维晶体几何学模型出发，计算出二苯甲酮晶体理想外形中各个晶面消失所需的最大临界生长速率，由此预测了各个晶面在晶习中消失的先后顺序。利用过冷熔体法在不同的过冷度条件下生长了二苯甲酮单晶，将单晶的实际生长习性进行比较，发现理论预测结果与实际生长习性变化比较吻合。