资源类型

期刊论文 60

年份

2023 5

2022 5

2021 2

2020 4

2018 2

2017 4

2016 4

2014 2

2013 9

2012 2

2011 5

2010 7

2009 6

2008 2

2006 1

展开 ︾

关键词

PP 1

WPC 1

严重事故 1

临界热流密度 1

协同晶化 1

压水堆 1

含铬废水 1

多晶型 1

常温 1

成核 1

控制方案 1

控制结晶工艺 1

晶体工程 1

晶体粒度分布 1

朗道和郎之万动力学模拟 1

混合悬浮混合出料结晶器(MSMPR) 1

熔池形成 1

熔池热工水力学 1

熔融物堆内滞留 1

展开 ︾

检索范围：

排序： 展示方式：

Utilizing melt crystallization fundamentals in the development of a new tabletting technology

Ahmed ABOUZEID,Sandra PETERSEN,Joachim ULRICH

《化学科学与工程前沿（英文）》 2014年 第8卷 第3期   页码 346-352 doi: 10.1007/s11705-014-1443-9

摘要： Increasing production effeciency and lowering costs are some of the many advantages melt crystallization technology offers over the conventional methodology of tabletting. A normal tablet consists of a pure shell or a coat and a separate core constituting the pharmaceutical active ingredient. Great emphasis is put on the purity of the shell since its purpose is to solely protect and deliver the active ingredient to its target. Melt crystallization is a purification (separation) process. It is discussed here for its ability to produce coated tablets, by separating the “coating” material from the “to be coated” material coming from one molten mixture. Molten drops of lutrol-ibuprofen mixture are produced using the drop forming technique. The subsequent analysis involves proving and quantifying the phase separation (coat purity). The mechanism of a crystallizing drop is shown as direct evidence of the ongoing process. Moreover, solidified tablet batches are analyzed for the purity of their coating by measuring the ibuprofen concentration. This optimization process is carried out through multiple stages of development and condition enhancements in order to produce the most pure tablet coating. As a result, a trial showing an almost purely coated tablet is presented here.

关键词： phase separation     melt crystallization     tablets     process optimization    

HTML PDF 收藏

Permeability analysis and seepage process study on crystal layer in melt crystallization with fractal

Xiaobin JIANG, Baohong HOU, Yongli WANG, Jingkang WANG

《化学科学与工程前沿（英文）》 2011年 第5卷 第4期   页码 435-441 doi: 10.1007/s11705-011-1139-3

摘要： In this paper a porous media seepage model was applied to analyze the permeability and study the seepage process of crystal pillar formed in the preparation of electronic grade phosphoric acid (EGPA). By inspecting the seeping process, the structure parameter of crystal pillar could be obtained. Two basic ideal models (perfectly separated model and perfectly connected model) were presented and a characterized factor was introduced to modify the model. A good simulation result was obtained which met the experiment result well. The relationship between and permeability were also discussed. The characterized factor showed potential application on optimizing process.

关键词： melt crystallization     porous media     fractal     permeability     hyperpure material     simulation    

HTML PDF 收藏

Kinetic roughening transition and missing regime transition of melt crystallized polybutene-1 tetragonal

Motoi YAMASHITA

《化学科学与工程前沿（英文）》 2009年 第3卷 第2期   页码 125-134 doi: 10.1007/s11705-009-0001-3

摘要： The morphology and lateral growth rate of polybutene-1 ( -PB1) have been investigated for crystallization from the melt over a wide range of crystallization temperatures from 50 to 110°C. The morphology of -PB1 crystals is a rounded shape at crystallization temperatures lower than 85°C, while lamellar single crystals possess faceted morphology at higher crystallization temperatures. The kinetic roughening transition occurs around 85°C. The nucleation and growth mechanism for crystallization does not work below 85°C, since the growth face is rough. However, the growth rate shows the supercooling dependence derived from the nucleation and growth mechanism. The nucleation theory seems still to work even for rough surface growth. Possible mechanisms for the crystal growth of this polymer are discussed.

关键词： isotactic polybutene-1     tetragonal phase (form Ⅱ)     melt crystallization     growth rate     kinetic roughening     morphology    

HTML PDF 收藏

Simulation of cottonseed cake melt flow in metering zone of a single screw extruder

Hong HE, Jianguo ZHOU,

《化学科学与工程前沿（英文）》 2010年 第4卷 第3期   页码 263-269 doi: 10.1007/s11705-009-0276-4

摘要： Research on the extrusion of natural polymers (food, feed, etc.) is relatively new due to the complex physicochemical transformations of raw materials, although plastics melt conveying and transport have been well studied. The structure and composition, rheological behavior as well as extrusion processing of natural polymer are much more complicated. In this study, a quasi-three-dimensional (3D) fluid flow model for non-Newtonian, non-isothermal and undeveloped temperature was developed, the model prediction being in reasonably good agreement with the experiment. Results show that the influence of moisture content, among other process variables, is the most significant, followed by screw speed. Some interaction exists between these two variables and the screw speed effect becomes marginal at high moisture contents. In addition, viscosity change in the channel was studied.

关键词： quasi-three-dimensional     rheological     viscosity     processing     influence    

HTML PDF 收藏

Lamellar thickness transition of melt-crystallized polybuten-1 tetragonal phase: configurational change

Motoi YAMASHITA

《化学科学与工程前沿（英文）》 2009年 第3卷 第1期   页码 26-32 doi: 10.1007/s11705-009-0002-2

摘要： Lamellar crystal thickness of isotactic polybutene-1 ( -PB1) have been investigated for crystallization in the melt over a wide range of crystallization temperature from 40°C to 90°C by small angle X-ray scattering experiments and density measurements. The crystal thickness demonstrates two linear dependences on inverse supercooling and a transition from one dependence to the other has been observed around = 65°C. Each of the two dependences obeys the nucleation theory in the high and low supercooling ranges, respectively. Chain folding free energy determined from the low supercooling range is larger than that determined from the high supercooling range. Possible mechanisms for the transition are discussed taking account of entropy of chain folding directions.

关键词： isotactic polybutene-1     tetragonal phase     crystal thickness     melt growth     chain folding     small angle X-ray scattering     nucleation theory     end surface free energy    

HTML PDF 收藏

Progress in membrane distillation crystallization: Process models, crystallization control and innovative

Xiaobin Jiang, Linghan Tuo, Dapeng Lu, Baohong Hou, Wei Chen, Gaohong He

《化学科学与工程前沿（英文）》 2017年 第11卷 第4期   页码 647-662 doi: 10.1007/s11705-017-1649-8

摘要： Membrane distillation crystallization (MDC) is a promising hybrid separation process that has been applied to seawater desalination, brine treatment and wastewater recovery. In recent years, great progress has been made in MDC technologies including the promotion of nucleation and better control of crystallization and crystal size distribution. These advances are useful for the accurate control of the degree of supersaturation and for the control of the nucleation kinetic processes. This review focuses on the development of MDC process models and on crystallization control strategies. In addition, the most important innovative applications of MDC in the last five years in crystal engineering and pharmaceutical manufacturing are summarized.

关键词： membrane distillation crystallization     mathematics model     nucleation     separation     hybrid process    

HTML PDF 收藏

Effects of a structurally related substance on the crystallization of paracetamol

Ali SALEEMI, I.I. ONYEMELUKWE, Zoltan NAGY

《化学科学与工程前沿（英文）》 2013年 第7卷 第1期   页码 79-87 doi: 10.1007/s11705-013-1308-7

摘要： Paracetamol (PCM) was crystallized from an isopropanol (IPA) solution containing various small amounts of metacetamol as an additive. The effect on the nucleation kinetics was studied by measuring the induction time to nucleation and the metastable zone width using focused beam reflectance measurements (FBRM) and attenuated total reflectance (ATR-UV/Vis) spectroscopy. Both the induction time and the metastable zone width were expressed as functions of the additive concentration. Small amounts of metacetamol (1–4 mol-%) were found to cause significant inhibition to the nucleation by extending both the induction time and the metastable zone width. A progressive change in the morphology of the paracetamol crystals from tabular to columnar habit was observed with increasing metacetamol concentration. The solvent also had a significant effect on the size of the paracetamol crystals as smaller crystals were obtained in IPA than in aqueous solution. The dissolution rate of paracetamol was improved by the incorporation of metacetamol with 4 mol-% having the most effect. A supersaturation control (SSC) approach was implemented for the PCM-IPA system with and without metacetamol in an attempt to control and obtain larger metacetamol-doped paracetamol crystals.

关键词： acetaminophen     metacetamol     crystallization     metastable zone width     induction time     supersaturation control    

HTML PDF 收藏

Interfacial induction and regulation for microscale crystallization process: a critical review

《化学科学与工程前沿（英文）》 2022年 第16卷 第6期   页码 838-853 doi: 10.1007/s11705-021-2129-8

摘要： Microscale crystallization is at the frontier of chemical engineering, material science, and biochemical research and is affected by many factors. The precise regulation and control of microscale crystal processes is still a major challenge. In the heterogeneous induced nucleation process, the chemical and micro/nanostructural characteristics of the interface play a dominant role. Ideal crystal products can be obtained by modifying the interface characteristics, which has been proven to be a promising strategy. This review illustrates the application of interface properties, including chemical characteristics (hydrophobicity and functional groups) and the morphology of micro/nanostructures (rough structure and cavities, pore shape and pore size, surface porosity, channels), in various microscale crystallization controls and process intensification. Finally, possible future research and development directions are outlined to emphasize the importance of interfacial crystallization control and regulation for crystal engineering.

关键词： interfacial crystallization     heterogeneous nucleation     supersaturation     micro/nanostructure     process control and intensification    

HTML PDF 收藏

压水堆熔融物堆内滞留策略：历史回顾与研究展望 Review

马卫民,元一单,Bal Raj Sehgal

《工程（英文）》 2016年 第2卷 第1期   页码 103-111 doi: 10.1016/J.ENG.2016.01.019

摘要：

本文对广泛应用于第三代压水堆的严重事故缓解措施——熔融物堆内滞留(IVR)进行了历史回顾。IVR策略最早源自于第二代反应堆Lovissa VVER-440的改进设计，以应对堆芯熔化事故。随后，IVR策略被应用于许多新设计的反应堆，如西屋的AP1000、韩国的APR1400以及中国的先进压水堆CAP1400和华龙一号。对IVR策略有效性影响最大的因素分别为堆内堆芯熔化进程、熔融物加载于压力容器壁面的热流密度和压力容器外部冷却。对于堆芯熔化进程，过去人们一直仅关注压力容器下腔室内熔池的换热行为。但通过回顾与分析，本文认为堆内的其他现象，如堆芯的降级和迁移、碎片床的形成及其可冷却性以及熔池的动态形成过程等，可能也会对熔池的最终状态及其作用于下封头的热负荷产生影响。通过对相关研究的回顾，本文希望找出IVR策略的研究中有待完善的部分，并据目前发展水平提出未来IVR研究的需求。

关键词： 压水堆     严重事故     熔融物堆内滞留     碎片床形成     碎片床再熔化     熔池形成     熔池热工水力学     临界热流密度    

HTML PDF 收藏

The feasibility of coating by cooling crystallization on ibuprofen naked tablets

Fatima Mameri, Ouahiba Koutchoukali, Mohamed Bouhelassa, Anne Hartwig, Leila Nemdili, Joachim Ulrich

《化学科学与工程前沿（英文）》 2017年 第11卷 第2期   页码 211-219 doi: 10.1007/s11705-017-1619-1

摘要： Sugar spray coating is a frequently used process in the pharmaceutical industry. However, this process presents the disadvantage to form an amorphous coating around the active ingredient. A crystalline coating formed on the surface of a tablet is highly desirable. Recently, a new process of coating by cooling crystallization has been developed and applied on bisacodyl pastilles obtained by melt crystallization. In this work, we investigated the feasibility of coating by cooling crystallization on ibuprofen “naked tablets” manufactured by compression. In the first part of this work, the solubility and the metastable zone width have been determined experimentally for the coating solution because they are essential factors for any crystallization process. In the second part, the coating process is investigated on the operating conditions that affect the surface morphology and the crystal growth rate. These experimental conditions include concentration of the coating solution, degree of sub-cooling, agitation speed, retention time, and surface properties of the naked ibuprofen tablets. The results show that naked tablet coating by cooling crystallization is feasible and can be applied in the pharmaceutical industry.

关键词： coating     solution crystallization     ibuprofen tablets     sucrose    

HTML PDF 收藏

Premature melt solidification during mold filling and its influence on the as-cast structure

M. WU, M. AHMADEIN, A. LUDWIG

《机械工程前沿（英文）》 2018年 第13卷 第1期   页码 53-65 doi: 10.1007/s11465-017-0437-y

摘要：

Premature melt solidification is the solidification of a melt during mold filling. In this study, a numerical model is used to analyze the influence of the pouring process on the premature solidification. The numerical model considers three phases, namely, air, melt, and equiaxed crystals. The crystals are assumed to have originated from the heterogeneous nucleation in the undercooled melt resulting from the first contact of the melt with the cold mold during pouring. The transport of the crystals by the melt flow, in accordance with the so-called “big bang” theory, is considered. The crystals are assumed globular in morphology and capable of growing according to the local constitutional undercooling. These crystals can also be remelted by mixing with the superheated melt. As the modeling results, the evolutionary trends of the number density of the crystals and the volume fraction of the solid crystals in the melt during pouring are presented. The calculated number density of the crystals and the volume fraction of the solid crystals in the melt at the end of pouring are used as the initial conditions for the subsequent solidification simulation of the evolution of the as-cast structure. A five-phase volume-average model for mixed columnar-equiaxed solidification is used for the solidification simulation. An improved agreement between the simulation and experimental results is achieved by considering the effect of premature melt solidification during mold filling. Finally, the influences of pouring parameters, namely, pouring temperature, initial mold temperature, and pouring rate, on the premature melt solidification are discussed.

关键词： premature solidification     mold filling     as-cast structure     modeling    

HTML PDF 收藏

Nucleic acid crystallization and X-ray crystallography facilitated by single selenium atom

Wen Zhang,Jack W. Szostak,Zhen Huang

《化学科学与工程前沿（英文）》 2016年 第10卷 第2期   页码 196-202 doi: 10.1007/s11705-016-1565-3

摘要： X-ray crystallography is a powerful strategy for 3-D structure determination of macromolecules, such as nucleic acids and protein-nucleic acid complexes. However, the crystallization and phase determination are the major bottle-neck problems in crystallography. Recently we have successfully developed synthesis and strategy of selenium-derivatized nucleic acids (SeNA) for nucleic acid crystallography. SeNA might not only provide the rational strategies to solve the phase determination problem, but also offer a potential strategy to explore crystallization solutions.

关键词： selenium     DNA     RNA     nucleic acid     crystallization    

HTML PDF 收藏

Preparation and crystallization kinetics of micron-sized Mg(OH)

Xingfu SONG, Kefeng TONG, Shuying SUN, Ze SUN, Jianguo YU

《化学科学与工程前沿（英文）》 2013年 第7卷 第2期   页码 130-138 doi: 10.1007/s11705-013-1332-7

摘要： Magnesium hydroxide is an important chemical, and is usually obtained from seawater or brine via precipitation process. The particle size distribution of magnesium hydroxide has great effects on the subsequent filtration and drying processes. In this paper, micron-sized magnesium hydroxide with high purity, large particle size and low water content in filter cake was synthesized via simple wet precipitation in a mixed suspension mixed product removal (MSMPR) crystallizer. The effects of reactant concentration, residence time and impurities on the properties of magnesium hydroxide were investigated by X-Ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Malvern laser particle size analyzer. The results show that NaOH concentration and residence time have great effects on the water content and particle size of Mg(OH) . The spherical Mg(OH) with uniform diameter of about 30 μm was obtained with purity higher than 99% and water content less than 31%. Furthermore, the crystallization kinetics based on the population balance theory was studied to provide the theoretical data for industrial enlargement, and the simulation coefficients ( ) based on ASL model and C-R model are 0.9962 and 0.9972, respectively, indicating that the crystal growth rate of magnesium hydroxide can be well simulated by the size-dependent growth models.

关键词： magnesium hydroxide     precipitation     micron-sized     crystallization kinetics    

HTML PDF 收藏

Applications of the crystallization process in the pharmaceutical industry

Sohrab ROHANI

《化学科学与工程前沿（英文）》 2010年 第4卷 第1期   页码 2-9 doi: 10.1007/s11705-009-0297-z

摘要： The applications of the crystallization technique in the pharmaceutical industry as a purification and separation process for the isolation and synthesis of pure active pharmaceutical ingredients (API), co-crystals, controlled release pulmonary drug delivery, and separation of chiral isomers are briefly discussed using a few case studies. The effect of process variables and solvent on the polymorphism and morphology of stavudine is discussed. The implementation of external control in the form of feedback and real-time optimal control using cooling and antisolvent crystallization of paracetamol in water-isopropyl alcohol is introduced. Two methods to prepare micron-sized drug particles, namely, micro-crystallization and polymer-coated API-loaded magnetic nanoparticles for pulmonary drug delivery, are discussed. The significance of co-crystals in drug administration is highlighted using the theophylline-nicotinamide co-crystal system. Resolution of chloromandelic acid derivatives, a racemic compound, is achieved using direct crystallization and diastereomeric salts crystallization. The crystal structures of diastereomeric salts of chloromandelic acid and phenylethylamine are determined. The structure comparison between the less soluble and more soluble salts shows that weak interactions such as CH/π interactions and van der Waals forces contribute to chiral recognition when the hydrogen bonding patterns are similar.

关键词： feedback     morphology     pulmonary     paracetamol     recognition    

HTML PDF 收藏

Importance of emulsions in crystallization—applications for fat crystallization

Sandra PETERSEN, K. CHALEEPA, Joachim ULRICH

《化学科学与工程前沿（英文）》 2013年 第7卷 第1期   页码 43-48 doi: 10.1007/s11705-013-1309-6

摘要： Emulsions and crystallization are two independent research topics which normally do not overlap although a combination of the two could be applicable to many areas. Here, the importance of emulsions in the field of fat crystallization is described. Three applications with industrial relevance were chosen for investigation: fat fractionation, the solidification of phase change materials and solid lipid nanoparticles. For fat fractionation and phase change materials, emulsification can be applied as a tool to improve the fat crystallization process, and thus the product quality of the crystallized fat. Furthermore, the use of emulsification creates new application fields such as solid lipid nanoparticles in the area of fat crystallization.

关键词： emulsion     fat crystallization     phase change material     emulsion fractionation     emulsion solidification    

HTML PDF 收藏

标题 作者 时间 类型 操作

Utilizing melt crystallization fundamentals in the development of a new tabletting technology

Ahmed ABOUZEID,Sandra PETERSEN,Joachim ULRICH

期刊论文

Permeability analysis and seepage process study on crystal layer in melt crystallization with fractal

Xiaobin JIANG, Baohong HOU, Yongli WANG, Jingkang WANG

期刊论文

Kinetic roughening transition and missing regime transition of melt crystallized polybutene-1 tetragonal

Motoi YAMASHITA

期刊论文

Simulation of cottonseed cake melt flow in metering zone of a single screw extruder

Hong HE, Jianguo ZHOU,

期刊论文

Lamellar thickness transition of melt-crystallized polybuten-1 tetragonal phase: configurational change

Motoi YAMASHITA

期刊论文

Progress in membrane distillation crystallization: Process models, crystallization control and innovative

Xiaobin Jiang, Linghan Tuo, Dapeng Lu, Baohong Hou, Wei Chen, Gaohong He

期刊论文

Effects of a structurally related substance on the crystallization of paracetamol

Ali SALEEMI, I.I. ONYEMELUKWE, Zoltan NAGY

期刊论文

Interfacial induction and regulation for microscale crystallization process: a critical review

期刊论文

压水堆熔融物堆内滞留策略：历史回顾与研究展望

马卫民,元一单,Bal Raj Sehgal

期刊论文

The feasibility of coating by cooling crystallization on ibuprofen naked tablets

Fatima Mameri, Ouahiba Koutchoukali, Mohamed Bouhelassa, Anne Hartwig, Leila Nemdili, Joachim Ulrich

期刊论文

Premature melt solidification during mold filling and its influence on the as-cast structure

M. WU, M. AHMADEIN, A. LUDWIG

期刊论文

Nucleic acid crystallization and X-ray crystallography facilitated by single selenium atom

Wen Zhang,Jack W. Szostak,Zhen Huang

期刊论文

Preparation and crystallization kinetics of micron-sized Mg(OH)

Xingfu SONG, Kefeng TONG, Shuying SUN, Ze SUN, Jianguo YU

期刊论文

Applications of the crystallization process in the pharmaceutical industry

Sohrab ROHANI

期刊论文

Importance of emulsions in crystallization—applications for fat crystallization

Sandra PETERSEN, K. CHALEEPA, Joachim ULRICH

期刊论文