用凝胶法生长KClO4晶体

凝胶法是生长KClO4晶体最合适的方法．实验研究了反应物浓度、凝胶密度、温度、凝胶pH值对KClO4晶体成核数目、大小、形状及质量的影响，得出了生长较大尺寸、完整性好、高质量的KClO4晶体的最佳条件和参数．第一次对KClO4晶体形态、各晶面的显露程度进行定量分析，实验与理论分析相符合．证实了Hartman和Perdok的PBC理论．研究结果为下一步进行晶体生长机理研究打下了基础．     

Synthesis of high quality type-Ib diamond crystals in carats grade

High quality type-Ib tower-shape gem-diamond crystals in carats grade were synthesized in cubic anvil high pressure apparatus (SPD-6×1200) at 5.4 GPa and 1250-1450°C. The relationship between the growth time and the weight of growth diamond has been gained. The faces of {110} and {113} were found in the synthetic diamond crystals frequently. We found that the relative growth rate of {113} face was descending with the increase of growth temperature, and that of {110} face had no obvious change with the incre...     

Simulating micrometre-scale crystal growth from solution

Understanding crystal growth is essential for controlling the crystallization used in industrial separation and purification processes. Because solids interact through their surfaces, crystal shape can influence both chemical and physical properties. The thermodynamic morphology can readily be predicted, but most particle shapes are actually controlled by the kinetics of the atomic growth processes through which assembly occurs. Here we study the urea-solvent interface at the nanometre scale and report kinetic Monte Carlo simulations of the micrometre-scale three-dimensional growth of urea crystals. These simulations accurately reproduce experimentally observed crystal growth. Unlike previous models of crystal growth, no assumption is made that the morphology can be constructed from the results for independently growing surfaces or from an a priori specification of surface defect concentration. This approach offers insights into the role of the solvent, the degree of supersaturation, and the contribution that extended defects (such as screw dislocations) make to crystal growth. It also connects observations made at the nanometre scale, through in situ atomic force microscopy, with those made at the macroscopic level. If extended to include additives, the technique could lead to the computer-aided design of crystals.     

金钱草提取液对尿液中草酸钙晶体生长的影响

采用经处理过的正常人尿液作为模拟体系,研究了金钱草对草酸钙晶体生长的影响.使用SEM,FT-IR和XRD等测试手段对所得晶体进行了表征.结果发现:在正常人尿液中生成了一水合草酸钙(COM)和二水合草酸钙晶体(COD);而当加入金钱草提取液后,一水合草酸钙晶体完全消失,二水合草酸钙晶体的尺寸也随着金钱草提取液的生药浓度增大而减小,说明金钱草可以很好地抑制尿结石的形成.从生物矿化的角度对金钱草抑制草酸钙晶体生长的可能机理进行了探讨.     

高白填料氢氧化铝的微观结构

不同分解工艺生产的高白填料,其氢氧化铝晶体生长形态不同.采用扫描电镜、X射线衍射和拉曼光谱等分析手段研究了碳分和种分氢氧化铝高白填料产品的微观结构,揭示了它们晶体发育的变化.结果表明,高白填料氢氧化铝晶体属单斜晶系,空间群P21/n,择优生长晶面均为(002)晶面;种分氢氧化铝晶体比碳分氢氧化铝晶体的(002)晶面择优取向因子值小,为多晶面生长;种分氢氧化铝晶体晶格参数比碳分氢氧化铝晶体晶格参数和拉曼光谱特征峰半高宽数值小,因此,种分高白填料氢氧化铝晶体中杂质和晶格缺陷比较少,晶体结晶度明显好于碳分高白填料产品.     

Effect of 6H-SiC crystal growth shapes on thermo-elastic stress in the growing crystal

The effect of 6H-SiC crystal growth shapes on the thermo-elastic stress distribution in the growing crystal was systematically investigated by using a finite element method. The thermo-elastic stress distribution in the crystal with a flat growth shape was more homogeneous than that in the crystals with concave and convex growth shapes, and the value of thermo-elasticity in the crystal with a flat growth shape was also smaller than that in the two other types of crystals. The maximum values of thermo-elastic stress appeared at interfaces between the crystal and the graphite lid. If the lid was of the same properties as 6H-SiC, the thermo-elastic stress would decrease in two orders of magnitude. Thus, to grow 6H-SiC single crystals of high quality, a transition layer of SiC formed by deposition or reaction is suggested; meanwhile the thermal field in the growth chamber should be adjusted to maintain the crystals with flat growth shapes.     

Rapid and reversible shape changes of molecular crystals on photoirradiation

The development of actuators based on materials that reversibly change shape and/or size in response to external stimuli has attracted interest for some time. A particularly intriguing possibility is offered by light-responsive materials, which allow remote operation without the need for direct contact to the actuator. The photo-response of these materials is based on the photoisomerization of constituent molecules (typically trans-cis isomerization of azobenzene chromophores), which gives rise to molecular motions and thereby deforms the bulk material. This effect has been used to create light-deformable polymer films and gels, but the response of these systems is relatively slow. Here we report that molecular crystals based on diarylethene chromophores and with sizes ranging from 10 to 100 micrometres exhibit rapid and reversible macroscopic changes in shape and size induced by ultraviolet and visible light. We find that on exposure to ultraviolet light, a single crystal of 1,2-bis(2-ethyl-5-phenyl-3-thienyl)perfluorocyclopentene changes from a square shape to a lozenge shape, whereas a rectangular single crystal of 1,2-bis(5-methyl-2-phenyl-4-thiazolyl)perfluorocyclopentene contracts by about 5-7 per cent. The deformed crystals are thermally stable, and switch back to their original state on irradiation with visible light. We find that our crystals respond in about 25 microseconds (that is, about five orders of magnitude faster than the response time of the azobenzene-based polymer systems) and that they can move microscopic objects, making them promising materials for possible light-driven actuator applications.     

Role of β(FeAl) nanoparticles in abnormal grain growth in the annealing of cast Cu-Al-Mn-Fe shape memory alloys

In this study, the low-cost production of Cu-Al-Mn-Fe shape memory alloy single crystals exceeding 46 mm by abnormal grain growth was realized only through annealing their cast alloys. The results show that the misorientation formed during annealing may be responsible for such abnormal grain growth process. It was confirmed that this misorientation resulted from the dissolution of bcc β(FeAl) nanoparticles during heat treatment at a sufficiently temperature of approximately 1173 K. The rate of migration of the abnormal grain boundary was experimentally measured to be approximately 9.3 × 10^-5 m s^-1 within 2 min of the commencement of abnormal grain growth. Additionally, the range of composition of the alloys that can lead to abnormal grain growth was determined. When the Cu-13.0Al-6.5Mn-3.2Fe single crystal close to the [100] direction was deformed to a pre-strain of 12%, full shape recovery happened without any residual strain. At that time, the superelastic strain was approximately 9%. Such a superelastic characteristic remained nearly constant over 50 cycles, showing excellent fatigue resistance. The superelastic properties of the present Cu-13.0Al-6.5Mn-3.2Fe single crystal are compared to those of commercial Ni-Ti-based shape memory alloys. Therefore, it can be considered as a new kind of superelastic material having practical applications. The obtained results should be of great significance in the development of Cu-based shape memory alloys. Furthermore, it is expected that a similar microstructure can be designed for the production of more metallic single crystals.     

超声辅助冷冻对湿面筋蛋白中可冻结水含量及冰晶粒度分布的影响

超声辅助食品冷冻过程是一种新的技术。本文通过对湿面筋蛋白中可冻结水含量及冰晶粒度分布的检测,研究超声辅助食品冷冻过程中冰结晶的热力学机制。用差示扫描量热仪测定了不同冷冻环境下湿面筋蛋白中可冻结水的含量,结果可见：超声辅助冷冻和液氮浸渍冷冻的湿面筋蛋白中可冻结水的含量比传统冷冻过程的高。用扫描电镜间接观察和分析了冷冻的湿面筋蛋白中冰晶的形状和粒度分布,表明适当的功率超声能加速湿面筋蛋白的冷冻过程;超声辅助和液氮浸渍冷冻的湿面筋蛋白中冰晶细小且分布均匀,可减少冷冻时对面筋蛋白网络结构的破坏。显示超声辅助冷冻是改善冷冻食品品质的实用技术。     

乌骨藤苷晶体对人宫颈腺癌荷瘤裸鼠肿瘤抑制 作用的实验研究

摘要: 目的 研究乌骨藤苷晶体对人宫颈腺癌荷瘤裸鼠肿瘤的抑制作用。方法 采用人宫颈腺癌接种裸鼠待长出 实体瘤,用第三代实体瘤移植裸鼠皮下建立人宫颈腺癌裸鼠模型; 用乌骨藤提取物苷晶体( I、II) ( 0. 24 g /250 mL) 分别给实验组裸鼠灌胃 0. 5 mL/只,对照组给饮用水,每日 1 次,连续 30 d。每周测量体质量和肿瘤大小 2 次,30 d 给药后处死小鼠,解剖,称其肿瘤质量,计算抑瘤率,评价乌骨藤提取物苷晶体( Ⅰ、Ⅱ) 对裸鼠荷瘤的抑制作用。结 果 乌骨藤苷晶体Ⅰ和晶体Ⅱ对人宫颈腺癌荷瘤裸鼠有抑制肿瘤作用,抑瘤率分别 88. 95 % 和66. 71 % ,其中晶体 Ⅰ和Ⅱ抑制肿瘤作用与对照组比较有显著性差异( 晶体Ⅰ,P ＜ 0. 01; 晶体Ⅱ,P ＜ 0. 05) 。结论 乌骨藤苷晶体Ⅰ和 晶体Ⅱ均有抑制人宫颈腺癌荷瘤裸鼠肿瘤的作用。     

水热法KTP晶体生长及形貌特征

晶体宏观形态和表面微形貌特征是晶体生长机制的具体反映,通过对晶体形貌特征的研究,探寻晶体生长的规律,为进一步改善晶体的质量打下基础。通过对水热法KTP晶体(磷酸钛氧钾,KT iOPO4,KTP)宏观形态和表面微形貌的研究,首次发现了KTP晶体中高指数晶面和{100}单形晶面上的螺旋生长纹,探讨发现高指数晶面和{100}单形晶面上螺旋纹的形成原因主要是溶液的过饱和度偏低以及籽晶的悬挂方式,为生长高质量的KTP晶体,提出了增大原材料溶解区与晶体生长区的温度差、改变籽晶的切向和悬挂方向等建议。     

烧结电除尘灰浸出液分离制备球形碳酸钙的研究

对包钢烧结电除尘灰进行了浸出试验,研究结果表明浸出液中有较高含量的钾盐和钙盐。为了提升钾盐产品质量和降低硫酸钙结垢对设备安全操作的影响,在回收钾盐之前,需要对浸出液中的硫酸钙盐进行去除。以碳酸钠溶液为沉淀剂,考察了沉淀剂浓度、反应温度、搅拌强度和平衡时间对浸出液中硫酸钙的去除效果及碳酸钙产品晶型晶貌的影响。结果表明,钙离子去除率几乎达到100%,同时获得了粒径10μm左右、颗粒分散均匀、高附加值的球形碳酸钙副产品。     

柠檬酸对二水石膏晶体生长习性与晶体形貌的影响

利用扫描电镜(SEM)、X射线光电子能谱(XPS)等测试手段分析了柠檬酸对二水石膏晶体结晶习性的影响,并从晶体生长的角度揭示了柠檬酸的缓凝机理．结果表明：柠檬酸由于能与钙离子发生络合作用,降低了钙离子在各个晶面上的叠合速率,从而减缓了石膏晶体的生长速率,晶体粗化;柠檬酸优先吸附在生长最快的c轴方向上,抑制c轴的生长,从而改变各个晶面的相对生长速率,晶形由针状变为短柱状;加入柠檬酸后,建筑石膏的缓凝、石膏硬化体强度的下降均与二水石膏晶体生长习性的改变息息相关．     

换热设备的超声防垢机理

通过探讨成垢晶体的结晶动力学过程和超声波对形成的CaCO3晶体形状和大小的影响,揭示了超声波防除积垢的机理．研究表明,超声处理可以缩短溶液中晶体的成核诱导期,提高晶核的生成速度,在溶液中迅速生成大量的微晶悬浮于溶液主体,晶粒长大速度减慢,成垢晶体不易沉积在管壁上。从而减少了积垢的形成．同时,超声的空化与机械作用增大了积垢在溶液中的溶解度,破坏了已形成的积垢。使其松软脱落．超声波还能改变生成的CaCO3晶体的形状及大小,改变形成的积垢的堆积形状,从而起到防垢的目的．工厂试验也表明。超声波防除积垢装置不但可以防止积垢的形成,而且可以有效地除去已形成的积垢,提高了蒸发系统的传热系数与蒸发强度,平均防垢率迭76．4％．     

第一类鱼抗冻蛋白分子对冰晶表面平衡结构的影响

根据冰晶生长理论,在一定的生长驱动力作用下,冰晶界面生长机制和动力学规律决定于冰晶界面的微观结构.从大分子溶液热力学性质出发,得到了结合抗冻蛋白后冰晶表面微观平衡结构的变化,并讨论了这种变化对冰晶生长形态的影响.结果显示抗冻蛋白造成冰晶表面微观平衡结构改变,是抗冻蛋白溶液中冰晶生长的形态与纯水中冰晶生长的形态有显著区别的原因之一.     

Growth and characterization of large, high quality cubic diamond crystals

High quality cubic diamond crystals were grown using the temperature gradient method at high pressure and high temperature(HPHT),in a new FeNi alloy as solvent.The crystals were grown at relatively low temperatures suitable for the growth of {100} faces.An increase in the radial growth rate,and inhibition of the axial growth caused the growth of large,high quality cubic diamond single crystals at high growth rates.For example,over 33 h,the radial growth rate was 0.22 mm/h,while the axial growth rate was only 0.08 mm/h;the growth rate by weight was also increased to 7.3 mg/h.The yellow color of our crystal samples was more uniform than samples from Sumitomo Corporation of Japan and Element Six Corp.The Raman FWHW of the 1332 cm 1 peak in our diamond sample was smaller than the Element Six Corp.sample,but larger than that of the Sumitomo Corp.sample.The nitrogen content of our diamond samples was 240 ppm,which was much higher than the Sumitomo and Element Six samples because of the higher growth rate of our diamond samples.     

热处理过程对湿化学法合成锂锰氧化物结构的影响

采用湿化学法在常压及温度低于100℃的水溶液中,使锂盐与锰盐发生化学反应生成LiMn     

HKUST-1形貌对QCM甲苯传感器敏感性能的影响

以室温超声法合成了不同形貌的金属有机框架化合物Cu_3(BTC)_2(HKUST-1)的纳米颗粒,并将其制作成石英晶体微天平(Quartz Crystal Microbalance, QCM)构建甲苯传感器.利用扫描电子显微镜,透射电子显微镜,X射线衍射仪,全自动比表面积和孔隙度分析仪,傅里叶变换红外光谱仪等对HKUST-1的形貌和结构进行了表征,测试了不同形貌和比表面积的敏感材料对甲苯的传感性能.结果证明不同晶粒尺寸和暴露晶面的HKUST-1对甲苯的敏感性能有明显影响.当形貌从低能晶面的八面体逐渐转变为高能晶面的立方体时,晶体尺寸变小,孔径逐渐增大.在空间位阻效应和吸附热效应的协同作用下,HKUST-1对甲苯气体显示出特异性吸附和敏感性能,其中高能晶面暴露最多的立方体形貌的HKUST-1对体积分数为60×10~(-6)甲苯气体的响应值比八面体样品高出1倍.     

Growth habit of polar crystals

Using coordination polyhedron rule, growth habit of polar crystals such as ZnO, ZnS and SiO₂ is investigated. It shows that the growth rates in the positive and negative polar axis directions are different. The theoretical growth habit of ZnO crystal is hexagonal prism and the growth rates of its various faces are: V_{0001} > V_{0111} >V_{0110} > V_{0111} > V_{0001}. The growth habit of ZnS crystal is tetrahedron and its growth rates of different crystal faces are: V_{111}>V_{001}>V_{001}=V_{100} = V_{010}>V_{111}. The growth rate relationship between positive and negative polar axis directions of SiO₂ crystal is V_[1120] > V_[1120]. These results are in agreement with the growth habits observed under hydrothermal conditions. The different growth rates between positive and negative polar axis directions cannot be explained by PBC theory.     

THE MECHANISM AND ENHANCING METHODS OF SOLVENTING OUT CRYSTALLIZATION

溶析结晶广泛用于有机工业结晶过程,但目前溶析结晶过程普遍存在着以下问题：晶体主粒度小,变异系数高;产品过滤分离难度大,杂质含量高．针对这些问题,本文研究了溶析结晶体系的介稳区性质,并采用了如下几种强化方法：用压力溶解和静置冷却来提高过饱和度;在沉淀剂中添加表面活性剂以及采用弹性叶片摩擦和超声波刺激来提高成核速率;动静态交替育晶减少生长分散;加入促进构型转变的物质获得所需晶型的晶体;按照最佳操作程序流加沉淀剂维持恒定的结晶过饱和度等．实验证明,采用这些方法可以显著地提高溶析结晶产品的质量．