Polycrystalline ZSM-5 Aggregates Induced by Seed and Catalytic Performance in Methanol to Hydrocarbon

Synthesis of ZSM-5 zeolite typically utilizes small molecule polyamines or quaternary ammonium salts as organic structure guiding agent(OSDA).By contrast,the OSDA-free hydrothermal synthesis system eliminates the use of organic templates and the subsequent calcination procedure.This not only reduces the cost of synthesis,but also prevents environmental pollution from the combustion of organic templates,representing an eco-friendly approach.Despite this,literature suggests that even so-called template-free synthesis systems often involve trace amount of organic substances like alcohol.In the present work,a calcined commercial ZSM-5 zeolite was served as seed,with sodium aluminate as aluminum source and silica sol as silicon source,ensuring an entirely template-free synthesis system.Polycrystalline ZSM-5 aggregates consisted of rod-like nanocrystals were successfully prepared in the completely OSDA-free system.Effects of the Si/Al ratio in ZSM-5 seed,dosage and crystallization conditions such as crystallization temperature and crystallization time on ZSM-5 synthesis were investigated.The results show that a highly crystallinity ZSM-5 aggregate consisting of primary nano-sized crystals less than 100 nm is produced from a gel precursor with 5.6%(in mass)seed after hydrothermal treatment for 48 h.Furthermore,the Si/Al ratio in ZSM-5 seed has little effect on the topological structure and pore structure of the synthesized samples.However,the seeds with a low Si/Al ratio facilitate faster crystallization of zeolite and enhance the acidity,especially the strong acid centers,of the catalyst.The catalytic performance of the synthesized polycrystalline ZSM-5 was evaluated during dehydration of methanol and compared with a commercial reference ZSM-5r.The results exhibit that as compared with the reference catalyst,the fabricated sample has a longer catalytic lifetime(16 h vs 8 h)attributed to its hierarchical pores derived from the loosely packed primary nanoparticles.Additionally,the prepared polycrystalline catalyst also exhibits a higher aromatics selectivity(28.1%-29.8%vs 26.5%).

THE STRUCTURE OF AGGREGATION STATE AND ISOTHERMAL CRYSTALLIZATION KINETICS OF NYLON-1010

The structure of aggregation state and isothermal crystallization behavior of Nylon-1010 have been studied by WAXD, DSE, Variance-Range Function and density measurement. The results show that crystallization of Nylon-1010 has the most suitable annealing temperature, the crystals of the Nxlon-1010 are two-dimension heterogeneous nucleation. Both low treatment temperature and high crystallization te, temperature are disadvantageous for Nylon-1010 crystal growth.

Synthesization and crystallization mechanism of nano-scale γ-AlOOH with various morphologies

Nano-scale γ-AIOOH with various morphologies, such as whisker, bar, ball, and sheet, was synthesized successfully and control- lably through a facile hydrothermal method just by adjusting the pH value of the solvent. Based on the analysis of the experimental data, the growth mechanism of nano-scale γ-AlOOH in the hydrothermal process was established. It is proposed that the growth unit and the growth direction are determined by the pH value of the solution and the growth unit, respectively. One-dimensional γ-AlOOH, such as whisker and bar, is formed in lower pH ranges, while two-dimensional γ-AlOOH sueli as sheet is formed only in high pH environment following the plane expansion crystallization mechanism.

Growth Pattern and Its Indication of Spheroidal Nano-Micro Crystal Aggregates of Pyrite in the Baiyunpu Pb-Zn Polymetallic Deposit, Central Hunan

The Baiyunpu deposit lies in the southwest plunging Dachengshan anticline in central Hunan, which is a large Pb-Zn polymetallic deposit. The orebodies were surrounded by the Qiziqiao Formation limestone in the Middle Devonian, and its geological occurrence is consistent with the wall rocks. A large number of spheroidal pyrite aggregates are found unevenly distributed in the ores. The spheroidal aggregates are made up of kernels and concentric rings. The kernels are composed of approximately epigranular pyrite nanocrystals, while the rings are composed of accumulated pyrite microcrystals growing along the radial direction. The spheroidal pyrite aggregate and its outer zones can be divided into five areas（A–E）. The results of electron probe micro analysis（EPMA） show that from the zone A1 to B, Co/Ni 〈1, the sum of Co and Ni is 0.08%–0.26%, S/Fe increases from 2.06 to 2.15. While from the zone C to E, Ni cannot be detected and S/Fe decreases from 2.22 to 2.08. Powder X-ray diffraction（XRD） analysis in the micro zone shows obvious crystalline characteristics in the aggregates. Moving from the inside outwards, the maximum diffraction peak intensity of the（111） and（220） crystal planes of pyrite increases, and the crystallinity improves. The degree of change in the（111） plane is the most prominent. Considering the theory of crystal growth along with the geologic features of the depositional environment where the spheroidal pyrite aggregates developed, we confirm that the spheroidal aggregates are the result of nano-micro crystalline gathering and growth occurring by the following sequence of processes：nano-crystalline nucleation and growth, gathering into a ball, oriented growth of microcrystals, continuous accumulation, and adjustment of grain boundaries. The formation of the spheroidal pyrite aggregates in the late Qiziqiao Formation of the Middle Devonian occurred in a neutral to weak alkaline and reductive sedimentary environment in the normal oxygen-rich shallowwater carbonate platform edge. The variations in the S/Fe ratio and crystallisation characteristics indicate that during pyrite crystal growth, the sulphur fugacity was high locally and rose constantly, the degree of supersaturation decreased locally and the growth environment was stable relatively.

Comparative experimental study on reactive crystallization of Ni(OH)2 in an airlift-loop reactor and a stirred reactor

The objective of this work is to study the reactive crystallization in an airlift-loop reactor （ALR） using the precipitation of Ni（OH）2 as a model reaction. The growth of Ni（OH）2 particles in an ALR and a stirred tank was quantified by scanning electronic microscope （SEM）, X-ray diffraction （XRD）, laser particle analyzer, tap densitometer and optical microscope, and the growth process of Ni（OH）2 particles is analyzed. It is found that the Ni（OH）2 particles prepared in an ALR have a better sphericity than those in a stirred tank and the growth of Ni（OH）2 particle tap density mainly depends on the size of crystallites： the bigger the size of crystallites, the bigger the tap density is. Based on these, the growth process of Ni（OH）2 particles in ALR is elaborated. Crystallites precipitated from solution aggregate to form large particles with much void. These constituting crystallites continue to grow up, that takes up the void inside particles and makes the tap densitv increase.

Synthesis, Structure and Aggregationinduced Emission Characteristics of Two Diaryquioxaline Derivatives

Two new diaryquioxaline derivatives, C21H10N2S3Br2（1） and C21H10Br2 N2OS2（2）,have been successfully synthesized. These two compounds have been determined by single-crystal X-ray diffraction analyses. Compound 1 crystallizes in monoclinic system, space group P21/n with a = 12.7896（3）, b = 6.0613（2）, c = 26.1153（7） ?, β = 94.1810（10）°, V = 2018.（97） ?3, Z = 4,C21H10N2S3Br2, Mr = 546.32, Dc = 1.797 g/cm3 and F（000） = 1072. The final R = 0.0343 and wR =0.785 for 3585 observed reflections with I > 2σ（I）. Compound 2 crystallizes in monoclinic system,space group P21/n with a = 7.8638（4）, b = 14.3447（7）, c = 17.8936（8） ?, β = 96.6980（10）°, V =2004.69（17） ?3, Z = 4, C21H10Br2 N2OS2, Mr = 530.25, Dc = 1.757 g/cm3 and F（000） = 1040. The final R = 0.0988 and wR = 0.1108 for 4613 observed reflections with I > 2σ（I）. By combination of diarylquinoxaline core and a 1,3-dithiole-2-thione unit, compound 1 is used as "turn on"chemosensors for Hg2+ by making use of the aggregation-induced emission（AIE） feature of diarylquinoxaline core and the specific reaction of 1,3-dithiole-2-thione with Hg2+.

MELTING AND CRYSTALLIZATION BEHAVIOR OFAN AROMATIC POLY (AZOMETHINE ETHER) WITH NON-LINEARLY SHAPED MOLECULAR CONFORMATIONS

The melting and crystallization behavior have been investigated for an aromatic poly (azomethine ether)with non-linearly shaped molecular conformations. This polymer was found to undergo multiple melting processes and its phase transition behavior was influenced sensitively by the thermal history of sample. A significant difference between the polymer chain aggregation abilities of samples cooled from the different states was observed. The possible molecular morphology and aggregation models for describing the structures of this polymer were proposed and discussed. The crystallization behavior of the samples cooled from the partially isotropic state and the influence of cooling rate on it have also been examined with DSC.

CRYSTALLIZATION AND MELTING OF POLY(ETHYLENE OXIDE)CONFINED IN NANOSTRUCTURED PARTICLES WITH CROSS-LINKED SHELLS OF POLYBUTADIENE

Small fixed aggregates of a poly(ethylene oxide)-block-polybutadiene diblock copolymer(PEO-b-PB)in THFsolution were obtained by adding a selective solvent for PB blocks,followed by cross-linking the PB shells.Themorphologies of the nanostructured particles with a cross-linked shell were investigated by atomic force microscopy andtransmission electron microscopy.The average behaviors of the PEO crystallization and melting confined within thenanostructured particles were studied by using differential scanning calorimetry experiments.For the deeply cross-linkedsample(SCL-1),the crystallization of the PEO blocks was fully confined.The individual nanoparticles only crystallized atvery low crystallization temperatures(T_cs),wherein the homogenous primary nucleation determined the overallcrystallization rate.For the lightly cross-linked sample(SCL-2),the confinement effect was T_c dependent.At T_c(?)42℃,thecrystallization and melting behaviors of SCL-2 were similar to those of the pure PEO-b-PB diblock copolymer.At T_c>42℃,SCL-2 could form PEO lamellae thicker than those of the pure PEO-b-PB crystallized at the same T_c.

Forward-Light-Scattering Characterization of Pre-Crystalline Aggregates in Crystallizing Lysozyme Solutions

We present a method to characterize lysozyme pre-crystalline aggregates using a forward-light-scattering technique, which is highly sensitive to protein aggregates. The static light scattering properties at small angles of crystallizing lysozyme aggregates are discussed, and related to the crystallization conditions based on the concentration of added precipitant NaCl. Lysozyme solutions that started to crystallize because of precipitant exhibited profiles of forward light scattering that could be fitted by non-integer power laws, which indicated fractal aggregations of lysozyme had formed. Pre-crystalline solutions, in which lysozyme crystals later grew, had dense structural fractal clusters with fractal dimensions of D > 1.5. In contrast, solutions with aggregates in which crystals did not grow, had forward-light-scattering profiles that deviated from a power law or had lower power values.

Kinetics and Mechanism of Spontaneous Crystallization of Potassium Nitrate from Its Supersaturated Aqueous Potassium Nitrate from Its Supersaturated Aqueous Solutions

Kinetics of spontaneous crystallization of potassium nitrate from its supersaturated aqueous solutions has been studied simultaneously by electrical conductance and optical transmittance methods. It was found that spontaneous crystallization of potassium nitrate was accompanied by aggregation of crystals. Growth of salt crystals was in the kinetic mode of the growth process, and was described by the equation of the first order regarding supersaturation of solution. The mechanism of aggregation and intergrowth of crystals during bulk crystallization via formation of nucleus-bridges between crystals found earlier for several salts was confirmed. Specific surface energy of potassium nitrate was evaluated on the basis of the above mechanism of aggregation and intergrowth of crystals. The established value of the specific surface energy was reasonable and agreed satisfactorily with the available literature data. Examination of crystal deposit after completion of crystallization allowed detecting crystal agglomerates of freakish and irregular forms, which may be considered as the direct confirmation of the above mechanism of intergrowth of crystals. Kinetics of crystallization, aggregation and size distribution of salt crystals after completion of crystallization have been satisfactory described by the earlier proposed model of the crystallization process. An excellent agreement was established between the experimental data on potassium nitrate solubility in aqueous solutions found in the present work and those available in the literature.

<i>In-Situ</i>Study of Non-Equilibrium Charge Carriers’ Behavior under Ultra-Short Pulsed Electrons Irradiation in Silicon Crystal

The recombination processes for charge carriers have been studied in n-type silicon crystals which were irradiated by pico-second duration pulse electrons with energy of 3.5 MeV (ultrafast irradiation), and maximum dose of 3.3 × 1013 el/cm2. In-situ measurements were carried out under artificial conditions simulating natural environment (space, semiconductor detectors, etc.). The observed phenomena were investigated experimentally in-situ using a high-speed oscilloscope equipped with a special preamplifier. Following irradiation to particular doses, some peculiarities of the recovery time of the semiconductor equilibrium condition (“characteristic time”), were obtained. Thus, it was found that the value of the “characteristic time” differs by an order of magnitude from the lifetime of the non-equilibrium (minority) charge carrier measured in an ex-situ regime. However, their behavior, as a function of irradiation dose, is similar and decreases with dose increase. Investigations of the dependencies of electro-physical parameters on irradiation dose, using Hall effect measurements, showed that at particular doses the radiation defects thus created, have an insignificant influence on the concentration of the charge carriers, but change their scattering properties appreciably, which affects the time parameters for the recombination of the semiconductor charge carriers. This investigation uses a novel approach to solid-state radiation physics, where in situ measurements were conducted in addition to conventional pre- and post-irradiation.

含蜡油气水合物生成特性及其浆液黏度影响因素

蜡、水合物及其耦合沉积是海洋油气多相混输工艺潜在风险问题。以天然气、去离子水、3#工业白油和石蜡为实验介质,依托可视化高压反应釜,基于正交实验设计的方法,分别选用L9(34)和L16(45)正交表设计并开展了无蜡和含蜡2种体系下天然气水合物生成实验;以流体当量黏度为评价指标,分析了含蜡量、搅拌速率、流体平衡温度、含水率、起始压力对水合物浆液当量黏度的影响显著程度。实验结果表明:黏度值恒定并不能判断反应釜中水合物生成是否结束,因为在剪切稳定阶段,脱离搅拌中心区域的水合物与搅拌区域新生成的水合物存在一种“动态平衡”状态;含蜡量越高,水合物生长诱导期越长;在含蜡量2%与3%水合物的快速生长阶段,扭矩与转速会发生2次突变,第1次突变原因是蜡晶的大量析出导致搅拌中心区域油相胶凝结构增强,第2次突变原因是水合物大量生成并与析出的蜡晶相互吸附形成了蜡-水合物聚集体,在离心作用下脱离了搅拌中心区域;各因素对于无蜡和含蜡体系水合物浆液当量黏度的影响显著程度相似,搅拌速率均为主要影响因素。研究结果对深水油气管道的安全运行具有重要的理论意义和实用价值。

表面活性聚集体稳定非水相泡沫的实验研究

非水相泡沫在化妆品、多孔材料、生物医药、油气开发等方向具有广泛的应用,然而表面张力较低等原因导致发泡困难,稳定性差,因此与泡沫相关的领域,一直是被攻克的难点。表面活性聚集体具有密度高,有序性良好等性质,可有效降低界面张力,被广泛应用于相关领域。文章以十二烷基磺酸钠、十二烷基苯磺酸钠为主剂,与甲酰胺和癸醇融合,制备出不同的表面活性聚集体并对其表征,观察非水相溶剂的起泡性和稳定性能。结果表明:表面活性聚集体均为层状液晶结构,属于非牛顿流体,有剪切-稀释的流变现象,并且表面活性剂的含量越高,表面活性聚集体层状液晶的结构越稳定,泡沫随层状液晶质量含量上升呈现出先增大后减少的趋势。SDBS/癸醇/甲酰胺的稳泡能力优于SDS/癸醇/甲酰胺,以甲酰胺为非水相时,SDBS/癸醇/甲酰胺中层状液晶为60%(w/%)时,泡沫稳定时长55 h以上。当非水相为癸醇时,SDBS/癸醇/甲酰胺中层状液晶为60%(w/%)时,泡沫稳定时长6 h以上。

多色有机室温磷光材料设计策略的研究进展

多色有机室温磷光(Room Temperature Phosphorescent,RTP)材料因其发射寿命长、颜色可调、生物相容性好以及激发态性质可调控等独特的性质,在显示技术、防伪、数据加密以及传感等领域展现出巨大的应用潜力,近年来受到了研究者的广泛关注。然而,受限于有机材料的三重态激子固有的敏感性,其三重态发光性质的调控成为了一个重大挑战。因此,在有机体系中实现多色且稳定的RTP发射仍然是一项亟待解决的问题。本文旨在综述近年来在多色有机RTP材料设计方面所取得的进展,重点介绍了卤素效应、晶体工程、聚集体效应以及主客体掺杂策略。通过精心选择和设计磷光分子,结合分子内/分子间相互作用和聚集态调控,成功实现了多种颜色的RTP发射。希望本文能为多色RTP材料的合理设计提供一定的思路,并为多色RTP材料的各种前沿应用提供一定的指导。

蓝相液晶对聚集诱导发光分子荧光性能的影响

为了拓宽蓝相液晶的应用范围,构建多功能化蓝相体系平台,本文将具有聚集诱导发光(AIE)特性的液晶TPE-PPE引入蓝相液晶体系,围绕复合体系的荧光性能展开研究。一方面,系统研究并归纳了手性添加剂含量对蓝相液晶相转变行为和光子带隙位移情况的影响;另一方面,探究了蓝相液晶对AIE分子荧光性能的影响,提出了相关荧光增强效应的假说。实验结果表明,不同手性添加剂体系的蓝相Ⅱ的温域范围基本一致,且反射带隙随着温度的降低发生蓝移;而蓝相Ⅰ的温域与手性密切相关,体系中仅存在蓝相Ⅰ时,其反射带隙随温度的降低而红移。蓝相液晶体系对AIE分子有一定的荧光增强效应,并且在整个蓝相温域内,蓝相Ⅰ的反射带隙红移,体系的荧光强度明显增强。由此得出结论,TPE-PPE分子在一定程度上参与了蓝相液晶体系的自组装。由于TPE-PPE分子在双螺旋柱结构中的受限运动,导致其荧光强度增强。随着蓝相Ⅱ的消失和蓝相Ⅰ光子带隙的红移,更多TPE-PPE分子参与到双螺旋柱的自组装中,体系的荧光发射增强。

基于四苯乙烯胆固醇衍生物的新型发光液晶材料研究

设计并制备了一种具有多胆固醇单元的新型四苯乙烯衍生物(TPE-SC).使用偏光显微镜(POM)、差示扫描量热法(DSC)、荧光光谱和X射线粉末衍射(XRD)研究了TPE-SC的凝聚相行为. TPE-SC表现出典型的胆甾醇型液晶的焦锥结构,具有有序的六方柱状中间相的液晶行为,并且在H2O-THF体系中具有优异的AIE性能.在室温下,固体膜的绝对荧光量子产率高达52.6%.这些发现不仅为材料科学领域提供了新的研究方向,而且为实际应用中可能需要的固态下具有高效率发光材料提供了重要参考.

Interplay between Micro-Anisotropy and Macro-Isotropy on Evolution of Non-Equilibrium Morphology

Non-equilibrium morphology has received much attention from both scientific and engineering points of view for its intricate pattern selection mechanisms and useful industrial application. Most study of non-equilibrium is about the metal, alloy and other simple system. The complex silicate system is rarely involved. However, silicate is very important in geosciences and ceramic industry. In this paper, two kinds of non-equilibrium crystal morphologies of silicate: dendrite of diopside and spherulite of plagioclase, were introduced. Combining with the other kinds of non-equilibrium morphologies, the characteristics of micro-macro and anisotropy-isotropy of the non-equilibrium morphologies were discussed. Dendrite of diopside is micro- and macro-anisotropic, spherulite of plagioclase is micro-anisotropic, but macro-isotropic, fractal of NH4Cl is also micro-anisotropic, but macro-isotropic, dense-branching morphology (DBM) formed in non-crystalline system is micro-and macro-isotropic. Based on the micro-macro interplay on the pattern formation, it is proposed that the interplay between micro-anisotropy of crystal structure vs macro-isotropy of undercooling in crystal growth system will control the morphological evolution. The nucleation rate related to the anisotropy for the morphological evolution was also discussed. The fact that diopside develops dendrite and plagioclase develop spherulite in our experiment is due to their structural anisotropy difference.

From crystalluria to kidney stones,some physicochemical aspects of calcium nephrolithiasis

Nephrolithiasis seems to be the result of crystal formation,aggregation and retention in the kidney during crystalluria.These processes have to occur within the short urinary transit time through the kidney being in the order of few minutes.Recently much work was done on rather qualitative aspects of nephrolithiasis like genetics,metabolism and morphology.In this review we try to provide some quantitative information on urinary supersaturation with respect to stone minerals,especially Ca oxalate(CaO x),on the formation and aggregation of Ca Ox crystals and on crystal retention in the kidney.The paper is centered on idiopathic Ca nephrolithiasis being the most frequent stone disease with only partially known pathogenesis.New aspects of the role of urinary macromolecules in stone formation and of the mechanism of crystal aggregation are provided.

Evolution of nitrogen structure in N-doped diamond crystal after high pressure and high temperature annealing treatment

In this paper, we have reported an investigation on the evolution of nitrogen structures in diamond crystals which contain nitrogen donor atoms in the range of 1500 ppm-1600 ppm following an annealing treatment at a high pressure of about 6.5 GPa and high temperatures of 1920 K-2120 K. The annealing treatment was found to completely transform nitrogen atoms originally arranged in a single substitutional form （C-center）, into a pair form （A-center）, indicated from infrared （IR） spectra. The photoluminescence （PL） spectra revealed that a small fraction of nitrogen atoms remained in C-center form, while some nitrogen atoms in A-center form were further transformed into N3 and H3 center structures. In addition, PL spectra have revealed the existence of two newly observed nitrogen-related structures with zero phonon lines at 611 nm and 711 nm. All these findings above are very helpful in understanding the formation mechanism of natural diamond stones of the Ia-type, which contains nitrogen atoms in an aggregated form.

Crystallization adn molecular aggregation of presynaptic neurotoxin from Agkistrodon halys pallas

Phospholipase A2 catalyzes specially the hydrolysis of the ester bond at the C2 position of3-sn-phosphoglycerides. Besides the enzymatic activity, the venom phospholipase A2 from varioussources displays complicated pharmacological activity and toxicity. The phospholipaseA2 neurotoxin is a noteworthy group in all phospholipase A2 species. It has been