液晶聚酯的液晶行为与加工性能

液晶聚酯由于具有特异的液晶行为和高强高模性能而越来越受到人们的关注。本文对液晶聚酯的液晶态形成原因、液晶态类型与链结构的关系、液晶态热稳定性及其成型加工性能进行了讨论，指出了提高液晶态热稳定性的方法及液晶聚酯的发展趋势。     

Recent progress of crystal growth modeling and growth control

With the rapid growth of electronic and optoelectronic industry, the demand for crystal materials increased dramatically for the past two decades. The requirement for better, cheaper, and larger single crystals has driven extensive research and development in crystal growth. To understand the interplay of associated transport processes and phase transformation, as well as to provide a design basis, crystal growth modeling is becoming more important in both fundamentals and practice. In this article, we review some recent progress of numerical modeling in crystal growth through three subjects: (1) hot-zone design, (2) active growth control, and (3) morphological simulation. Examples are given through our research results in recent years. For better illustration and process understanding some visualization results using transparent materials are given. The needs and the challenges ahead for crystal growth modeling are also discussed.     

异相结/异质结TiO2光催化机理及降解有机物的研究

到目前为止TiO2是较为成熟的半导体光催化材料，但因TiO2分散性差、量子利用率低、比表面积小、难回收等问题难以工业化。多孔金属有机框架MOFs的引入可增强TiO2/MOFs复合材料的光吸收性能，提高电子-空穴对分离和提高回收率。基于TiO2/MOFs制备时前驱体添加顺序不同，综述了TiO2/MOFs的三种制备方法（即Ship-in-a-bottle法、Bottle-around-ship法、One-pot法）及TiO2/MOFs光催化机理与性能影响因素，并探讨不同MOFs与TiO2结合的作用机理。最后，对TiO2/MOFs存在的问题提出建议。     

TRANSIENT ANALYSIS OF CRYSTALLIZATION: EFFECT OF THE SIZE DEPENDENT GROWTH RATE

The dynamics of the crystal size distribution in a continuous mixed suspension, mixed product removal crystallizer is modeled stochastically. The model is fairly general in that it involves a size-dependent growth rate function: this size-dependent growth rate as a possible cause of deviation on the behavior of the crystallizer from that of an idealized or simplified counterpart has been investigated based upon the model.     

有机小分子接枝炭黑填充PP复合材料的结晶行为与力学性能研究

将炭黑与有机小分子在Haake转矩流变仪中进行混合，通过高剪切力的作用，实现了有机小分子在炭黑表面的接枝改性。通过对比接枝改性后的炭黑（GCB）与接枝改性前的炭黑（CB）对聚丙烯（PP）性能的影响，发现GCB能更有效地促使PP基体发生异相成核，提高基体的结晶温度，使聚丙烯的韧性和强度都有明显提高。TEM结果表明，炭黑表面经过接枝有机小分子后粒径变小，在聚丙烯中能更好地分散。DSC结果表明CB和GCB对PP基体的结晶行为都会产生影响，但GCB的影响更加显著。添加1％GCB后，PP的结晶峰值温度提高了11．6℃。添加量仅为1％时，材料的缺口冲击强度，屈服强度和弯曲强度都有明显提高。     

The role of Al in C-S-H: NMR, XRD, and compositional results for precipitated samples

X-ray diffraction, compositional analysis, and ²⁹Si and ²⁷Al MAS NMR spectroscopy of Al-substituted tobermorite-type C-S-H made by precipitation from solution provide significant new insight into the structural mechanisms of Al-substitution in this important and complicated phase. Al occurs in 4-, 5-, and 6-coordination (Al[4], Al[5], and Al[6]) and plays multiple structural roles. Al[4] occurs on the bridging tetrahedra of the drierkette Al-silicate chains, and Al[5] and Al[6] occur in the interlayer and perhaps on particle surfaces. Al does not enter either the central Ca-O sheet or the pairing tetrahedra of the tobermorite-type layers. Al[4] occurs on three types of bridging sites, Q³ sites that bridge across the interlayer; Q² sites that are charge balanced by interlayer Ca⁺², Na⁺, or H⁺; and Q² sites that are most likely charge balanced by interlayer or surface Al[5] and Al[6] through Al[4]-O-Al[5,6] linkages. Although the data presented here are for relatively well-crystallized tobermorite-type C-S-H with C/S ratios ≤ 1.2, comparable spectral features for hydrated white cement pastes in previously published papers[30], [31] and [32] [M.D. Andersen, H.J. Jakobsen, J. Skibsted, Incorporation of aluminum in the calcium silicate hydrate (C-S-H) of hydrated Portland cements: a high-field ²⁷Al and ²⁹Si MAS NMR investigation Inorg. Chem. 42 (2003) 2280-2287; M.D. Andersen, H.J. Jakobsen, J. Skibsted, Characterization of white Portland cement hydration and the C-S-H structure in the presence of sodium aliminate by ²⁷Al and ²⁹Si MAS NMR spectroscopy, Cem. Concr. Res. 43 (2004) 857-868; M.D. Andersen, H. J. Jakobsen, J. Skibsted, A new aluminum-hydrate phase in hydrated Portland cements characterized by ²⁷Al and ²⁹Si MAS NMR spectroscopy, Cem. Concr. Res., submitted for publication.] indicate the presence of similar structural environments in the C-S-H of such pastes, and by implication OPC pastes.     

[Zn(BDC)(H2O)2]n: a novel blue luminescent coordination polymer constructed from BDC-bridged 1-D chains via interchain hydrogen bonds (BDC = 1,4-benzenedicarboxylate)

A novel coordination polymer [Zn(BDC)(H₂O)₂]_n 1 (where BDC = 1,4-benzenedicarboxylate), has been synthesized and characterized by X-ray diffraction. 1 crystallizes in the monoclinic space group C2/c, a=15.09(2) Å, b=5.058(7) Å, c=12.196(16) Å, β=103.62(2)°, , Z=4. The most striking feature of 1 is that it consists of a high-dimensional network structure constructed from BDC-bridged 1-D chains via interchain hydrogen bonds. The coordination sphere of the zinc(II) ion is a distorted tetrahedron completed by four oxygen atoms from two water molecules and two BDC ligands. BDC adopts the bis-monodentated (syn–anti) coordination mode linking two adjacent zinc(II) ions. 1 shows strong blue photoluminescence as the result of the fluorescence from the intraligand emission excited state.     

Crystal shape monitoring and supersaturation measurement in cooling crystallization with quartz crystal oscillator

A crystallization monitoring system using a quartz crystal oscillator was utilized to predict different shapes of crystal formation by measuring crystal growth rate and to measure supersaturation. Applying different rates of cooling, crystal formation of different shapes was induced, and the frequency variation of the oscillator and the crystal shape observed with an SEM were compared to determine how the frequency variation can be interpreted for the prediction of produced crystal shape. The experimental results obtained from the crystallization of potassium nitrate and cupric sulfate solutions showed that the proposed frequency measurement technique could be applied in the prediction of crystal shape of cooling crystallization processes. In addition, supersaturation was determined from the measurements of solution and coolant temperatures.     

Crystal transformation from the α- to the β-form upon tensile drawing of poly(l-lactic acid)

A film of poly(l-lactic acid) (PLLA) consisting of highly oriented α crystals was uniaxially drawn by tensile force. The effects of the draw ratio (DR), draw temperature (T_d), and draw stress on the crystal/crystal transformation from the α- to the β-form crystals were studied. At the initial stage of drawing, the highly oriented α crystals of the starting film transformed into a broader orientation distribution, and significant crystal disorder was introduced. Upon further drawing, the α crystals steadily transformed into β crystals with increasing the DR. For the drawing at a constant T_d, the crystal transformation proceeded more efficiently at a higher draw rate and, hence, at a higher draw stress. Furthermore, for the drawing at a constant draw rate, the transformation proceeded with DR most efficiently for the tensile draw at a T_d around 140 °C, although the draw stress increased with decreasing the T_d. The present result combined with the previous finding in the drawing of PLLA by solid-state extrusion [Macromolecules 36 (2003) 3601] suggests that there is a T_d of around 140 °C at which the crystal transformation proceeds most efficiently with DR, suggesting that there are two factors that have opposite effects on the efficiency of the crystal transformation with increasing the T_d. However, as a result of the combined effects of the T_d and DR on the crystal transformation and the ductility increase with the T_d, an oriented film consisting predominantly of β crystals was obtained by tensile drawing at a T_d in the range of 140-170 °C to the highest DR achieved at each T_d.     

水晶球模拟在R＆D决策中的运用

研究与开发（Research and Development,R＆D）投资、传统贴现现金流量（DiscountedCash Flow,DCF）方法忽略了项目自身管理弹性的价值;实物期权虽能较好地捕捉管理弹性的价值,却未能有效解决高度不确定环境下参变量的波动性问题;蒙特卡罗模拟能解决参变量的波动性问题,但需要复杂的计算机程序来解决算法问题.作者在分析实物期权的基础上,运用蒙特卡罗理论,使用水晶球软件来进行R＆D决策分析.通过实例证明,水晶球模拟方法可以更为科学有效地解决高度不确定条件下的R＆D决策问题.