Molecular Crystal Microcapsules: Formation of Sealed Hollow Chambers via Surfactant-Mediated Growth

Hollow organic molecular cocrystals comprised of 9-methylanthracene-1,2,4,5-tetracyanobenzene (9MA-TCNB) and naphthalene-1,2,4,5-tetracyanobenzene (NAPH-TCNB) were fabricated using a surfactant-mediated co-reprecipitation method. The crystals exhibit a narrow size distribution that can be easily tuned by varying the concentration of surfactant and incubation temperature. The rectangular crystals possess symmetrical twinned cavities with an estimated storage volume on the order of 10⁻¹⁰ L. An aqueous dye solution can be incorporated into the cavities during crystal growth and stored inside for up to several hours, confirming the sealed nature of the hollow chambers. Our results demonstrate that it is possible to harness non-classical crystal growth to fabricate organic molecular crystals with novel topologies.     

配液结晶法制备溶菌酶蛋白质晶体的生长机理研究

采用配液结晶法制取了溶菌酶蛋白质晶体, 使用动态光散射测量了溶液中聚集体的颗粒度几率分布; 使用Zeiss显微镜测定了溶菌酶(110)晶面的生长速度. 实验表明: 随着蛋白质和NaCl浓度的增加, 溶液中聚集体的颗粒尺寸也相应增加. 随着反应时间的增加, 溶菌酶分子在溶液中的聚集反应, 逐渐达到平衡; 在蛋白质和NaCl浓度较高时, 溶菌酶晶体的(110)面生长较快, 而在蛋白质和NaCl浓度较低时, 该晶面生长较慢. 基于二维成核生长机理, 从晶体生长动力学理论方程出发, 计算了二维成核的形成能α＝4.01×10^－8 J•cm^－2.     

石英晶体微天平用于免疫球蛋白M免疫反应的动力学研究

在镀银电极的压电石英晶体表面涂覆甲基丙烯酸甲酯－甲基丙烯酸羟乙酯共聚物涂层，经ＣＮＢｒ活化后固定抗体，用石英晶体微天平技术监测ＩｇＭ抗原在压电石英晶体上的吸附与解吸过程，研究了免疫反应体系ＩｇＭ－抗人ＩｇＭ的反应动力学．结果表明：ＩｇＭ在压电石英晶体上的键合行为很好地符合Ｌａｎｇｍｕｉｒ吸附方程，免疫反应的结合常数Ｋａｓｓ为７．１０×１０￣７（ｍｏｌ／Ｌ）￣（－１）．在抗原过量情况下为一级反应。计算了ＩｇＭ免疫反应的活化能Ｅａ和不同温度下的反应速率常数ｋｆ．     

Physico-geometric kinetics of solid-state reactions by thermal analyses

The physico-geometric kinetics for the solid-state reactions by thermoanalytical (TA) measurements were reexamined by focusing some fundamental aspects: (1) the fundamental kinetic equation, (2) the kinetic model function, (3) the fractional reaction , and (4) the apparent kinetic parameters. It was pointed out that some pitfalls in the practical kinetic study are originated by the disagreement between the kinetic information from the TA measurements and the theory of the physico-geometric kinetics. In order to increase the degree of coordination between the theory and practice, several attempts were made from both the theoretical and experimental points of views. The significance of the apparent kinetic parameters was discussed with a possible orientation for obtaining the reliable kinetic parameters.I would like to thank to Profs H. Tanaka, J. esták, J. M. Criado, A. K. Galwey and Dr. J. Malek for their kind supports.     

表面能与晶体生长/溶解动力学研究的新动向

界面现象使物质在结晶过程中出现了临界现象.但最近的研究指出在物质溶解过程中,在表面能量的控制下也存在着临界现象以及尺寸效应.实验发现,当晶体自身小到一 定的程度时(通常在纳米尺度上并和临界蚀坑的大小相近),在溶解过程中其速度会自发降 低,反应被抑制乃至停止.尽管在热力学上表面能的因素可以赋予小颗粒晶体较大的溶解度 ,但表面能却也能通过对临界条件的控制而使这些微粒在动力学上不被溶解.这个发现不仅 解决了纳米颗粒在水溶液中稳定性的问题,而且还从动力学的角度解释了生物矿物选择纳米 尺度作为其基本构成单元的原因.由于表面能和晶体生长/溶解的动力学有着密切的关系, 我们可以通过对表面能的调节来修改它们的动力学速度和晶体的形貌.反过来,也可以用动力学的方法来测定表面能及表面吸附/脱附常数等.相对于常规的界面研究手段,通过生 长和溶解动力学途径所得的数据有着很好的可靠性及重复性.我们认为,晶体生长和溶解的 动力学和表面能的研究相结合,不仅为界面研究提供了新的思路和方法,而且也会推动晶体生长和材料科学的发展.     

Pt在多晶Au微盘电极上电沉积成核与晶体生长

于不同H2PtCl6浓度和超电势下,应用Fleischmann的电结晶成核及晶体生长模型和Barradas Bosco的电化学成相吸附成核模型,拟合多晶Au微盘电极( =30μm)上电沉积Pt的恒电势阶跃电流暂态曲线.得出:在稀H2PtCl6溶液中,上述沉积过程初期,发生H2PtCl6吸附并遵循二维瞬时成核与圆柱形生长模型.二维生长速率常数随超电势线性增加.跟随其后的是核的层状生长,其速率常数随超电势呈非线性变化.而在高浓H2PtCl溶液中,沉积机理转变为H2PtCl6的吸附、瞬时成核及三维正圆锥形的生长模式.其晶核的垂直生长速率常数kPERP比水平生长速率常数kPARA大两个数量级以上.况且,logkPERP随超电势线性增加,而logkPARA则随超电势呈反S形变化的关系.相同超电势下,无论kPERP还是kPARA,均比稀H2PtCl6溶液中的二维层状生长速率常数大几个数量级.     

The Influence of the Thermal Behaviour of AgGaS2 on the Crystal Growth Process

Differential thermal analysis has been carried out on AgGaS₂ samples in order to investigate the relationship between the superheating of the melt and the supercooling behaviour of the material leading to an improvement of crystal growth conditions. The knowledge gained will be correlated to the crystal growth experiments which had been carried out by using the gradient freezing method.This revised version was published online in November 2005 with corrections to the Cover Date.     

Study of Growth Mechanism of Lysozyme Crystal by Batch Crystallization Method

Space environment is regarded as the perfect environment for the production of higher quality protein crystals since the sedimentation movement and convective flow due to the gravity is negligible under the microgravity condition of space environment. A n…     

不同阻垢剂对硫酸钙结晶生长诱导期影响的动力学探讨

阻滞作用;聚丙烯酸;马丙共聚物;不同阻垢剂对硫酸钙结晶生长诱导期影响的动力学探讨     

A New Kinetic Method of Processing TA Data

A new method of investigating the kinetic parameters and mechanism functions of a solid phase reaction is presented. This method is to analyze the data based on the use of these data at the same temperature and the same degree of conversion on a series of TA curves with different heating rates, so that the kinetic triplet--the activation energy E, the pre-exponential factor A and the analytical form of the function of conversionf(α) can be obtained. The main advantage of this method is that the values of E and f(α) are obtained respectively, and the determination of f(α) is not under the influence of the value of E and the calculation of the value of E is not influenced by thef(α) either.     

双羟基复合金属氧化物的晶面生长选择性及晶粒尺寸控制

采用成核／晶化隔离法合成镁铝双羟基复合金属氧化物（LDH）,考察了晶化温度及晶化时间对晶体结构,晶面生长选择性及晶粒尺寸的影响规律。结果发现晶化温度相同时,随晶化时间延长,LDH的晶体结构趋于完整,晶粒尺寸增大;晶化时间相同时,随晶化温度升高,晶体结构趋于完整,晶粒尺寸显著增大,实验条件下得到的LDH,其沿a轴方向的尺寸均大于沿c轴方向的尺寸,即共沿a轴方向的生长速率比沿c轴方向的生长速度快,亦即[110]晶面的生长速率比[003]晶面的生长速率快。根据LDH晶粒尺寸随晶化时间及晶化温度的变化规律,选择合适的晶化条件,制备得到了粒径分布窄的纳米LDH。     

水解法制备的掺铁二氧化钛超微粉的热分析、晶粒生长和结构相变

研究了用四氯化钛水解制备的纯二氧化钛和分步沉淀,共沉淀方式制备的掺铁二氧化钛的热分解状况,品化过程。采用Ｘ射线衍射和Ｖｏｉｇｔ单峰分析法计算了这三种样品在各个燃烧温度下的晶体晶粒度。结果表明,四氯化钛水争方法得到的二氧化钛粉为无定形,无定形博物经钛加热晶化过程是一个持续的过程,并没有以往文献中所报道的明显的晶化温度和晶化放热峰。应用非晶物质晶化晶核生长速率方程了晶粒生长活化能并且进行了讨论。     

Controlling Nucleation and Crystal Growth of a Distinct Polyoxovanadate Cluster: An In Situ Energy Dispersive X‐ray Diffraction Study under Solvothermal Conditions

The formation of the antimonato polyoxovanadates [V₁₄Sb₈(C₆H₁₅N₃)₄O₄₂(H₂O)] ? 4H₂O ( 1 ), (C₆H₁₇N₃)₂[V₁₅Sb₆(C₆H₁₅N₃)₂O₄₂(H₂O)] ? 2.5H₂O ( 2 ), {C₆H₁₅N₃}₄[V₁₆Sb₄O₄₂] 2H₂O ( 3 ) (C₆H₁₅N₃=1‐(2‐aminoethyl)piperazine, AEP) has been studied under solvothermal conditions by using in situ energy dispersive X‐ray diffraction (EDRXD). The syntheses were performed with an identical ratio for Sb₂O₃ and NH₄VO₃. If the reactions slurries are not stirred during the solvothermal reaction and by applying 70–75 % amine concentration, the products contain all three compounds, whereas 3 is observed at 80 %. Under stirring conditions, variation of the concentration of AEP led to crystallization of the three different compounds at distinct concentrations, that is, 1 is formed at 75 %, 1 and 2 between 75 and 80 % and 3 at 80 %. At an amine concentration of 77.5 %, first reflections of 2 occurred and at later stages, compound 1 started to crystallize. The sample with the lowest number of V^IV species was formed at the lowest amine concentration, whereas crystallization of 3 required the highest concentration. The formation of the compounds occurred without crystalline intermediates and/or precursors. With increasing reaction temperature, the incubation time was significantly reduced.     

金属Cu液固转变及晶体生长的分子动力学模拟

采用分子动力学模拟研究了液态Ｃｕ在不同冷却速度下的凝固特点,模拟采用ＥＡＭ作用势,计算了不同温度,不同冷却速度下Ｃｕ的偶相关函数,结果表明ＥＡＭ作用势能很好地描述液态Ｃｕ的结构特征,当冷却速度较快时,液Ｃｕ形成非晶;当冷却速度较慢时,液Ｃｕ形成晶体,分析了不同冷却速度下体系的相变热力学及相变动力学过程,最后采用液固两层构型法,描述了Ｃｕ晶体的生长过程。     

掺杂YAlO3晶体的温梯法生长及缺陷分析

采用温梯法工艺进行了掺铈和掺镱铝酸钇（YAlO3或YAP）晶体的生长实验。用同步辐射白光形貌表征了晶体内部生长层的分布情况，结果表明。温梯法生长掺杂YAP晶体的过程中，固-液界面形状比较平坦，这使得所生长的晶体具有较高的微观结构完整性；采用高分辨四晶摇摆曲线对其进行了表征，其主要晶面的半峰宽值均优于提拉法晶体。分析了生长过程中产生的主要缺陷，认为开裂主要来源于坩埚对晶体形成的压应力；而晶体中存在的色心主要与生长炉内的弱还原气氛有关。     

Synthesis, Crystal Structure and Kinetic Mechanism of Thermal Decomposition of a Zinc(II) Complex with N-Salicylidene-p-toluidine

1 INTRODUCTION Over the past decades, considerable attention has been devoted to the synthesis, characterization and property studies of Schiff bases and their com- plexes because of their potential and developed appli- cations in the fields of conducting and magnetic ma- terials, dyes, non-linear optics, catalysis, analytical chemistry, biochemical research, agriculture and so on[1～7]. A large number of reports are available in the chemistry and biologic activities of transition metal co…     

Formation of Hybrid Perovskite Tin Iodide Single Crystals by Top‐Seeded Solution Growth

Hybrid perovskites have generated a great deal of interest because of their potential in photovoltaic applications. However, the toxicity of lead means that there is interest in finding a nontoxic substitute. Bulk single crystals of both cubic CH₃NH₃SnI₃ and CH(NH₂)₂SnI₃ were obtained by using the top‐seeded solution growth method under an ambient atmosphere. Structural refinement, band gap, thermal properties, and XPS measurements of CH₃NH₃SnI₃ and CH(NH₂)₂SnI₃ single crystals are also reported in detail. These results should pave the way for further applications of CH₃NH₃SnI₃ and CH(NH₂)₂SnI₃.     

Crystal Growth Kinetics of Nanocrystalline ZnS under Surface Adsorption

The crystal growth mechanism,kinetics,and microstructure development play a fundamental role in tailoring the materials with controllable size and morphology. In this study,by introducing the strong surface adsorption of the concentrated NaOH,two-stage crystal growth kinetics of ZnS nanoparticles was observed. In the first stage,the primary particles grow into a size over a hundred times of the original volume and the growth is controlled by the crystal-lographically specific oriented attachment. The first stage data were fitted by the "multistep OA kinetic model" built based on the molecular collision and reaction. In the second stage,following the dispersal of nanoparticles,an abrupt transition from asymptotic to parabola growth kinetics occurs,which can be fitted by a standard Ostwald ripening volume diffusion model. The presence of surface adsorption causes the two-stage growth kinetics and permits an almost exclusive OA-based growth to dominate in the first stage.