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Dynamic modulation performance of ferroelectric liquid crystal polarization rotators and Mueller matrix

Song ZHANG, Lelun WANG, Anze YI, Honggang GU, Xiuguo CHEN, Hao JIANG, Shiyuan LIU

《机械工程前沿（英文）》 2020年 第15卷 第2期   页码 256-264 doi: 10.1007/s11465-019-0573-7

摘要： A ferroelectric liquid crystal polarization rotator (FLCPR) has been widely used in polarization measurement due to its fast and stable modulation characteristics. The accurate characterization of the modulation performance of FLCPR directly affects the measurement accuracy of the instrument based on liquid crystal modulation. In this study, FLCPR is accurately characterized using a self-developed high-speed Stokes polarimeter. Strong linear and weak circular birefringence are observed during modulation processes, and all the optical parameters of FLCPR are dependent on driving voltage. A dual FLCPR-based Mueller matrix polarimeter is designed on the basis of the Stokes polarimeter. The designed polarimeter combines the advantages of the high modulation frequency of FLCPR and the ultrahigh temporal resolution of the fast polarization measurement system in the Stokes polarimeter. The optimal configuration of the designed polarizer is predicted in accordance with singular value decomposition. A simulated thickness measurement of a 24 nm standard SiO thin film is performed using the optimal configuration. Results show that the relative error in thickness measurement caused by using the unsatisfactory modulation characteristics of FLCPR reaches up to −4.34%. This finding demonstrates the importance of the accurate characterization of FLCPR in developing a Mueller matrix polarizer.

关键词： ferroelectric liquid crystal polarization rotator (FLCPR)     dual liquid crystal Mueller matrix polarizer     design and optimization    

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Research progress on ultra-precision machining technologies for soft-brittle crystal materials

Hang GAO,Xu WANG,Dongming GUO,Yuchuan CHEN

《机械工程前沿（英文）》 2017年 第12卷 第1期   页码 77-88 doi: 10.1007/s11465-017-0411-8

摘要：

Soft-brittle crystal materials are widely used in many fields, especially optics and microelectronics. However, these materials are difficult to machine through traditional machining methods because of their brittle, soft, and anisotropic nature. In this article, the characteristics and machining difficulties of soft-brittle and crystals are presented. Moreover, the latest research progress of novel machining technologies and their applications for soft-brittle crystals are introduced by using some representative materials (e.g., potassium dihydrogen phosphate (KDP), cadmium zinc telluride (CZT)) as examples. This article reviews the research progress of soft-brittle crystals processing.

关键词： brittle     soft     functional crystal     ultra-precision machining    

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Crystal-to-crystal transformation from the triclinic to the cubic crystal system by partial desolvation

Qianqian Guo, Irmgard Kalf, Ulli Englert

《化学科学与工程前沿（英文）》 2018年 第12卷 第3期   页码 433-439 doi: 10.1007/s11705-018-1743-6

摘要：

Diffusion reaction of the labile building block Mg(acacCN)2 (acacCN= 3-cyanoacetylacetonate) with silver salts leads to a series of solvated Mg/Ag bimetallic coordination polymers with composition [Mg(acacCN)3Ag]·solvent. Despite their common stoichiometry, the topology of these polymers depends on the solvent of crystallization. The two-dimensional coordination compound [Mg(acacCN)3Ag]·4CHCl3 in space group P1‾ is obtained as platelet-shaped crystals from a mixture of methanol and chloroform. When kept in the reaction mixture, these thin plates within one week convert to isometric tetrahedral crystals of the 3D network [Mg(acacCN)3Ag]·2CHCl3 in the cubic space group P213. The transformation reaction proceeds via dissolution and recrystallization. The co-crystallized solvent molecules play an important role for stabilizing the target structure: They subtend Cl···Cl contacts and interact via non-classical C–H···O hydrogen bonds with the coordination framework. In the new cubic coordination network, both Mg(II) and Ag(I) adopt octahedral coordination, with unprecedented face-sharing by bridging O atoms of three acetylacetonato moieties. Prolonged standing of [Mg(acacCN)3Ag]·2CHCl3 in the reaction medium leads to further degradation, under formation of [Ag(acacCN)].

关键词： ditopic ligand     substituted acetylacetone     desolvation     diffraction    

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Effect of hierarchical ZSM-5 zeolite crystal size on diffusion and catalytic performance of n-heptane

Shuman Xu, Xiaoxiao Zhang, Dangguo Cheng, Fengqiu Chen, Xiaohong Ren

《化学科学与工程前沿（英文）》 2018年 第12卷 第4期   页码 780-789 doi: 10.1007/s11705-018-1733-8

摘要： Hierarchical ZSM-5 zeolite aggregates with different sizes of nanocrystals were synthesized using different amounts of the mesoporogen 3-aminopropyltriethoxysilane. The effect of the crystal size on the catalytic cracking of -heptane was investigated and the Thiele modulus and effectiveness factor were used to determine the reaction rate-limiting step. The crystal size affected the textual properties of the catalysts but not the acidic properties of the catalysts. The reaction rate was first order with respect to the -heptane concentration. Cracking over hierarchical zeolites with nanocrystal sizes larger than about 50 nm took place under transition-limiting conditions, whereas the reaction over hierarchical zeolites with nanocrystal sizes of 15 or 30 nm proceeded under reaction control conditions. Hierarchical ZSM-5 zeolite aggregates with smaller nanocrystals had better selectivity for light olefins which can be ascribed to the shorter diffusion path lengths and lower diffusion resistance in these catalysts. Furthermore, these catalysts had lower coking levels which can be attributed to the substantial number of mesopores which prevent the formation of coke precursors.

关键词： hierarchical ZSM-5     crystal size     catalytic cracking     Thiele modulus     effectiveness factor    

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Theoretical insights into influence of additives on sulfamethoxazole crystal growth kinetics and mechanisms

《化学科学与工程前沿（英文）》 2023年 第17卷 第10期   页码 1503-1515 doi: 10.1007/s11705-022-2294-4

摘要： In this work, the influence of the initial chemical potential gradient, stirring speed, and polymer type on sulfamethoxazole (SMX) crystal growth kinetics was systematically investigated through density functional theory (DFT) calculations, experimental measurements and the two-step chemical potential gradient model. To investigate the influence of different conditions on the thermodynamic driving force of SMX crystal growth, SMX solubilities in different polymer solutions were studied. Four model polymers effectively improved SMX solubility. It was further found that polyvinylpyrrolidone (PVP) and hydroxypropyl methyl cellulose (HPMC) played a crucial role in inhibiting SMX crystal growth. However, polyethylene glycol (PEG) promoted SMX crystal growth. The effect of the polymer on the crystal growth mechanisms of SMX was further analyzed by the two-step chemical potential gradient model. In the system containing PEG 6000, crystal growth is dominated by the surface reaction. However, in the system containing PEG 20000, crystal growth is dominated by both the surface reaction and diffusion. In addition, DFT calculations results showed that HPMC and PVP could form strong and stable binding energies with SMX, indicating that PVP and HPMC had the potential ability to inhibit SMX crystal growth.

关键词： insoluble drugs     polymer     inhibition crystallization     crystal growth kinetics     DFT calculations    

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Novel casting processes for single-crystal turbine blades of superalloys

Dexin MA

《机械工程前沿（英文）》 2018年 第13卷 第1期   页码 3-16 doi: 10.1007/s11465-018-0475-0

摘要：

This paper presents a brief review of the current casting techniques for single-crystal (SC) blades, as well as an analysis of the solidification process in complex turbine blades. A series of novel casting methods based on the Bridgman process were presented to illustrate the development in the production of SC blades from superalloys. The grain continuator and the heat conductor techniques were developed to remove geometry-related grain defects. In these techniques, the heat barrier that hinders lateral SC growth from the blade airfoil into the extremities of the platform is minimized. The parallel heating and cooling system was developed to achieve symmetric thermal conditions for SC solidification in blade clusters, thus considerably decreasing the negative shadow effect and its related defects in the current Bridgman process. The dipping and heaving technique, in which thin-shell molds are utilized, was developed to enable the establishment of a high temperature gradient for SC growth and the freckle-free solidification of superalloy castings. Moreover, by applying the targeted cooling and heating technique, a novel concept for the three-dimensional and precise control of SC growth, a proper thermal arrangement may be dynamically established for the microscopic control of SC growth in the critical areas of large industrial gas turbine blades.

关键词： superalloy     investment casting     Bridgman process     directional solidification     single crystal     turbine blade    

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Polymorphism and crystal transformation of penicillin sulfoxide

Dingding JING, Yongli WANG, Zhijian CHEN, Lina ZHOU, Jingkang WANG

《化学科学与工程前沿（英文）》 2011年 第5卷 第4期   页码 442-447 doi: 10.1007/s11705-011-1140-x

摘要： Penicillin sulfoxide is the intermediate for the synthesis of 7-amino-3-desacetoxycephalosporanic acid which is one of the most important nucleuses of cephalosporin antibiotic. In this contribution, two crystal structures of penicillin sulfoxide (forms I and II) were determined by X-ray diffraction, and their thermotropic properties were investigated by differential scanning calorimetry (DSC). Furthermore, the transformation of form II to form I was studied quantitatively by Raman spectroscopy, and its rates at different temperatures were determined. The results indicate that penicillin sulfoxide is more stable as form I, and the temperature plays an important role in the crystal transformation.

关键词： penicillin sulfoxide     crystallization     polymorphism     crystal transformation     Raman spectroscopy    

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Biosorption and biotransformation of crystal violet by

Tao PAN, Suizhou REN, Jun GUO, Meiying XU, Guoping SUN

《环境科学与工程前沿（英文）》 2013年 第7卷 第2期   页码 185-190 doi: 10.1007/s11783-012-0435-6

摘要： DN322p, an offspring of DN322, has the capacity to adsorb and decolorize triphenylmethane dyes in wastewater simultaneously. As a common triphenylmethane dye, crystal violet (CV) was chosen to test the decolorization characteristics of DN322p. Within 0.5 h, the strain DN322p adsorbed a large amount of CV, producing a deep-colored cell pellet and colorless supernatant. The colors of the cell pellet and supernatant lightened over time. The supernatant and dichloromethane extract of the cell pellet both showed conspicuous CV and leuco CV (LCV) characteristic absorbance peaks at 590 nm and 260 nm, respectively, in the UV-vis spectral analysis. This finding indicated that the DN322p cells can adsorb the two dyes. A 99% (w/w) decolorization rate was achieved within 2.5 h with shaking at 30°C for 50 mg CV·L . High Performance Liquid Chromatography (HPLC) analysis of the dichloromethane extract of the supernatant and cell pellet confirmed that CV was mainly converted into its leuco form. Dead cells had a similar adsorption capacity with living cells. About 90% of CV in the dye solution (50 mg·L ) was removed by autoclaved cells with an optical delnsity at 600 nm (OD ) above 1.0.

关键词： crystal violet     decolorization     biosorption     biotransformation     Aeromonas hydrophila DN322p    

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Computer modeling of crystal growth of silicon for solar cells

Lijun LIU, Xin LIU, Zaoyang LI, Koichi KAKIMOTO

《能源前沿（英文）》 2011年 第5卷 第3期   页码 305-312 doi: 10.1007/s11708-011-0155-9

摘要： A computer simulator with a global model of heat transfer during crystal growth of Si for solar cells is developed. The convective, conductive, and radiative heat transfers in the furnace are solved together in a coupled manner using the finite volume method. A three-dimensional (3D) global heat transfer model with 3D features is especially made suitable for any crystal growth, while the requirement for computer resources is kept permissible for engineering applications. A structured/unstructured combined mesh scheme is proposed to improve the efficiency and accuracy of the simulation. A dynamic model for the melt-crystal (mc) interface is developed to predict the phase interface behavior in a crystal growth process. Dynamic models for impurities and precipitates are also incorporated into the simulator. Applications of the computer simulator to Czochralski (CZ) growth processes and directional solidification processes of Si crystals for solar cells are introduced. Some typical results, including the turbulent melt flow in a large-scale crucible of a CZ-Si process, the dynamic behaviors of the mc interface, and the transport and distributions of impurities and precipitates, such as oxygen, carbon, and SiC particles, are presented and discussed. The findings show the importance of computer modeling as an effective tool in the analysis and improvement of crystal growth processes and furnace designs for solar Si material.

关键词： computer modeling     silicon     crystal growth     solar cells    

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Evaluation method of multiaxial low cycle fatigue life for cubic single crystal material

CHEN Jiping, DING Zhiping

《机械工程前沿（英文）》 2007年 第2卷 第3期   页码 278-282 doi: 10.1007/s11465-007-0048-0

摘要： The coupling effect of normal stress and shear stress on orthotropic materials happens when applied loading deflects from the directions of the principal axes of the material coordinate system. By taking account of the coupling effects, formulas of equivalent stress and strain for cubic single crystal materials are cited. Using the equivalent strain and equivalent stress for such material and a variable k, which is introduced to express the effect of asymmetrical cyclic loading on fatigue life, a low cycle fatigue (LCF) life prediction model for such material in multiaxial stress starts is proposed. On the basis of the yield criterion and constitutive model of cubic single crystal materials, a subroutine to calculate the thermo elastic-plastic stress-strain of the material on an ANSYS platform was developed. The cyclic stress-strain of DD3 notched specimens under asymmetrical loading at 680vH was analyzed. Low cycle fatigue test data of the single crystal nickel-based superalloy are used to fit the different parameters of the power law with multiple linear regression analysis. The equivalent stress and strain for a cubic single crystal material as failure parameters have the largest correlation coefficient. A power law exists between k and the failure cycle. The model was validated with LCF test data of CMSX-2 and DD3 single crystal nickel-based superalloys. All the test data fall into the factor of 2.5 for CMSX-2 hollow cylinder specimens and 2.0 scatter band for DD3 notched specimens, respectively.

关键词： orthotropic     regression analysis     crystal material     multiaxial     prediction    

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LCF behavior and life prediction method of a single crystal nickel-based superalloy at high temperature

Zhihua ZHANG,Huichen YU,Chengli DONG

《机械工程前沿（英文）》 2015年 第10卷 第4期   页码 418-423 doi: 10.1007/s11465-015-0362-x

摘要：

Low cycle fatigue tests were conducted on the single crystal nickel-based superalloy, DD6, with different crystallographic orientations (i.e., [001], [011], and [111]) and strain dwell types (i.e., tensile, compressive, and balanced types) at a certain high temperature. Given the material anisotropy and mean stress, both orientation factor and stress range were introduced to the Smith, Watson, and Topper (SWT) stress model to predict the fatigue life. Experimental results indicated that the fatigue properties of DD6 depend on both crystallographic orientation and loading types. The fatigue life of the tensile, compressive, and balanced strain dwell tests are shorter than those of continuous cycling tests without strain dwell because of the important creep effect. The predicted results of the proposed modified SWT stress method agree well with the experimental data.

关键词： life prediction     single crystal superalloy     low cycle fatigue (LCF)     crystallographic orientation     strain dwell    

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Study on the crystal morphology and melting behavior of isothermally crystallized composites of short

Mingtao RUN, Hongzan SONG, Yanping HAO

《化学科学与工程前沿（英文）》 2009年 第3卷 第3期   页码 255-264 doi: 10.1007/s11705-009-0008-9

摘要： The spherulites of the short carbon fiber(SCF)/poly (trimethylene terephthalate) (PTT) composites formed in limited space at designed temperatures, and their melting behaviors were studied by the polarized optical microscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM), respectively. The results suggest that SCF content, isothermal crystallization temperatures, and the film thicknesses influence the crystal morphology of the composites. The dimension of the spherulites is decreased with increasing SCF content, but whether banded or nonbanded spherulites will form in the composites is not dependent on SCF content. However, the crystal morphology of the composites depends strongly on the temperature. When the isothermal crystallization temperatures increase from 180°C to 230°C, the crystal morphology of SCF/PTT composites continuously changes in the following order: nonbanded → banded → nonbanded spherulites. Discontinuous circle lines form in the film when the film thickness increases from 30 to 60 μm. Basing on the SEM observation, it is found that these circle lines are cracks formed due to the constriction difference of the different parts of the spherulites. These cracks are formed when the film is cooled from the isothermal crystallization temperature to the room temperature at a slow cooling rate; while they will disappear gradually at different temperatures in the heating process. The crack will appear/disappear first around the center of the spherulite when the film was cooled/heated. The nontwisted or slightly twisted lamellas will reorganize to form highly twisted lamellas inducing apparent banded texture of the spherulites.

关键词： poly(trimethylene terephthalate)     short carbon fiber     banded spherulites     crack    

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Solvability and thermal response of cellulose with different crystal configurations

Qian CHEN, Kai ZHENG, Qingtao FAN, Kun WANG, Haiyan YANG, Jianxin JIANG, Shijie LIU

《工程管理前沿（英文）》 2019年 第6卷 第1期   页码 62-69 doi: 10.1007/s42524-019-0001-z

摘要：

Cellulose is a biodegradable and renewable natural material that it is naturally resistant to breaking and modification. Moreover, the crystalline structure of cellulose is a major factor restricting its industrial utilization. In this study, cellulose polymorphs were prepared from natural cellulose, and their solvability and thermal response were investigated. Using liquid- and solid-state NMR signals, the distinct types and dissolving states of cellulose polymorphs were identified. The thermal behavior of the polymorphic forms of cellulose-d was also evaluated, and cellulose II exhibited the poorest thermal stability and a unique exothermic reaction.

关键词： cellulose     crystal structure     thermal response     XRD     CP/MAS 13C NMR    

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Existence of complete band gaps in 2D steel-water phononic crystal with square lattice

Cunfu HE, Huanyu ZHAO, Ruiju WEI, Bin WU

《机械工程前沿（英文）》 2010年 第5卷 第4期   页码 450-454 doi: 10.1007/s11465-010-0105-y

摘要： This paper theoretically and experimentally studies the existence of complete band gaps in two-dimensional (2D) phononic crystal consisting of parallel steel rods in water with square lattice. The band structure of phononic crystal is calculated by a plane wave expansion (PWE) method. Based on the well-known ultrasonic immersion transmission technique, the overlapping transmission spectra of acoustic waves, a complete band gap, is experimentally measured along the two high-symmetry directions of the first irreducible Brillouin zone. There is a very good agreement between the experimental result and the range of frequencies of the complete band gap.

关键词： phononic crystal     plane wave expansion (PWE) method     experimental study    

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Introduction to the special issue of the 2009 International Symposium on Crystal Engineering & Drug Delivery

Zhijian CHEN, Wei LI,

《化学科学与工程前沿（英文）》 2010年 第4卷 第1期   页码 1-1 doi: 10.1007/s11705-009-0306-2

摘要：
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标题 作者 时间 类型 操作

Dynamic modulation performance of ferroelectric liquid crystal polarization rotators and Mueller matrix

Song ZHANG, Lelun WANG, Anze YI, Honggang GU, Xiuguo CHEN, Hao JIANG, Shiyuan LIU

期刊论文

Research progress on ultra-precision machining technologies for soft-brittle crystal materials

Hang GAO,Xu WANG,Dongming GUO,Yuchuan CHEN

期刊论文

Crystal-to-crystal transformation from the triclinic to the cubic crystal system by partial desolvation

Qianqian Guo, Irmgard Kalf, Ulli Englert

期刊论文

Effect of hierarchical ZSM-5 zeolite crystal size on diffusion and catalytic performance of n-heptane

Shuman Xu, Xiaoxiao Zhang, Dangguo Cheng, Fengqiu Chen, Xiaohong Ren

期刊论文

Theoretical insights into influence of additives on sulfamethoxazole crystal growth kinetics and mechanisms

期刊论文

Novel casting processes for single-crystal turbine blades of superalloys

Dexin MA

期刊论文

Polymorphism and crystal transformation of penicillin sulfoxide

Dingding JING, Yongli WANG, Zhijian CHEN, Lina ZHOU, Jingkang WANG

期刊论文

Biosorption and biotransformation of crystal violet by

Tao PAN, Suizhou REN, Jun GUO, Meiying XU, Guoping SUN

期刊论文

Computer modeling of crystal growth of silicon for solar cells

Lijun LIU, Xin LIU, Zaoyang LI, Koichi KAKIMOTO

期刊论文

Evaluation method of multiaxial low cycle fatigue life for cubic single crystal material

CHEN Jiping, DING Zhiping

期刊论文

LCF behavior and life prediction method of a single crystal nickel-based superalloy at high temperature

Zhihua ZHANG,Huichen YU,Chengli DONG

期刊论文

Study on the crystal morphology and melting behavior of isothermally crystallized composites of short

Mingtao RUN, Hongzan SONG, Yanping HAO

期刊论文

Solvability and thermal response of cellulose with different crystal configurations

Qian CHEN, Kai ZHENG, Qingtao FAN, Kun WANG, Haiyan YANG, Jianxin JIANG, Shijie LIU

期刊论文

Existence of complete band gaps in 2D steel-water phononic crystal with square lattice

Cunfu HE, Huanyu ZHAO, Ruiju WEI, Bin WU

期刊论文

Introduction to the special issue of the 2009 International Symposium on Crystal Engineering & Drug Delivery

Zhijian CHEN, Wei LI,

期刊论文