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Molecular dynamics simulation of diffusivity

LIU Juanfang, ZENG Danling, LI Qin, GAO Hong

《能源前沿(英文)》 2008年 第2卷 第3期   页码 359-362 doi: 10.1007/s11708-008-0039-9

摘要: Equilibrium molecular dynamics simulation was performed on water to calculate its diffusivity by adopting different potential models. The results show that the potential models have great influence on the simulated results. In addit

关键词: diffusivity     Equilibrium molecular     influence     potential    

A computational toolbox for molecular property prediction based on quantum mechanics and quantitative

《化学科学与工程前沿(英文)》 2022年 第16卷 第2期   页码 152-167 doi: 10.1007/s11705-021-2060-z

摘要: Chemical industry is always seeking opportunities to efficiently and economically convert raw materials to commodity chemicals and higher value-added chemical-based products. The life cycles of chemical products involve the procedures of conceptual product designs, experimental investigations, sustainable manufactures through appropriate chemical processes and waste disposals. During these periods, one of the most important keys is the molecular property prediction models associating molecular structures with product properties. In this paper, a framework combining quantum mechanics and quantitative structure-property relationship is established for fast molecular property predictions, such as activity coefficient, and so forth. The workflow of framework consists of three steps. In the first step, a database is created for collections of basic molecular information; in the second step, quantum mechanics-based calculations are performed to predict quantum mechanics-based/derived molecular properties (pseudo experimental data), which are stored in a database and further provided for the developments of quantitative structure-property relationship methods for fast predictions of properties in the third step. The whole framework has been carried out within a molecular property prediction toolbox. Two case studies highlighting different aspects of the toolbox involving the predictions of heats of reaction and solid-liquid phase equilibriums are presented.

关键词: molecular property     quantum mechanics     quantitative structure-property relationship     heat of reaction     solid-liquid phase equilibrium    

Determination of the diffusion of poly(ethylene glycol) in polypropylene using ATR-FTIR

Hanjia CHEN, Xuhua SHI, Yafei ZHU, Yi ZHANG, Jiarui XU,

《化学科学与工程前沿(英文)》 2010年 第4卷 第3期   页码 336-341 doi: 10.1007/s11705-009-0230-5

摘要: The diffusion of poly(ethy1ene glycol) (PEG) in polypropylene (PP) was investigated using attenuated total reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Atomic Force Micrograph (AFM), and Scanning Electron Microscopy (SEM). It has been found that the diffusion of PEG in PP was greatly affected by the annealing temperature and the molecular weight of PEG. Higher temperature was in favor of PEG to diffuse in PP with fast velocity and reached diffusion equilibrium with shorter time. PEG with higher molecular weight was distributed in PP with bigger phase domains and had lower diffusivity, which resulted in its lesser enrichment on the surface of the PP blend film.

关键词: diffusion     polypropylene     molecular     diffusion equilibrium     attenuated    

聚酰胺反渗透膜中水传递阻力的分子模拟——界面阻力和内部阻力 Article

宋阳, 魏明杰, 徐放, 汪勇

《工程(英文)》 2020年 第6卷 第5期   页码 577-584 doi: 10.1016/j.eng.2020.03.008

摘要:

在分子水平上理解水分子在聚酰胺(PA)反渗透(RO)膜中的传递阻力对于这些膜的设计、制备和应用具有非常重要的指导意义。本文通过分子模拟来计算总传递阻力,并将其分成两部分——内部阻力和界面阻力。内部阻力取决于PA层的厚度,而界面阻力则不然。基于5 nm 厚的PA层的模拟显示界面阻力对总阻力的贡献率很大(> 62%)。然而,现实世界中,对于具有200 nm PA层的RO膜,界面阻力起次要作用,其贡献率低于10%。这表明,当使用典型方法估算RO膜的传递阻力时,存在不准确的风险,因为该方法简单地将5 nm厚的PA层的总阻力进行倍增,使得界面阻力被错误放大。此外,界面阻力和内部阻力均取决于PA层的化学性质。我们的模拟显示,减少PA层中剩余羧基的数量会导致内部阻力降低,因此,可以在不牺牲离子截留的情况下改善水的渗透性,这与实验结果高度吻合。

关键词: 传递阻力     反渗透     非平衡分子动力学     水分子亲水性     建模    

Thermodynamic analysis of reaction pathways and equilibrium yields for catalytic pyrolysis of naphtha

《化学科学与工程前沿(英文)》 2022年 第16卷 第12期   页码 1700-1712 doi: 10.1007/s11705-022-2207-6

摘要: The chain length and hydrocarbon type significantly affect the production of light olefins during the catalytic pyrolysis of naphtha. Herein, for a better catalyst design and operation parameters optimization, the reaction pathways and equilibrium yields for the catalytic pyrolysis of C5–8 n/iso/cyclo-paraffins were analyzed thermodynamically. The results revealed that the thermodynamically favorable reaction pathways for n/iso-paraffins and cyclo-paraffins were the protolytic and hydrogen transfer cracking pathways, respectively. However, the formation of light paraffin severely limits the maximum selectivity toward light olefins. The dehydrogenation cracking pathway of n/iso-paraffins and the protolytic cracking pathway of cyclo-paraffins demonstrated significantly improved selectivity for light olefins. The results are thus useful as a direction for future catalyst improvements, facilitating superior reaction pathways to enhance light olefins. In addition, the equilibrium yield of light olefins increased with increasing the chain length, and the introduction of cyclo-paraffin inhibits the formation of light olefins. High temperatures and low pressures favor the formation of ethylene, and moderate temperatures and low pressures favor the formation of propylene. n-Hexane and cyclohexane mixtures gave maximum ethylene and propylene yield of approximately 49.90% and 55.77%, respectively. This work provides theoretical guidance for the development of superior catalysts and the selection of proper operation parameters for the catalytic pyrolysis of C5–8 n/iso/cyclo-paraffins from a thermodynamic point of view.

关键词: naphtha     catalytic pyrolysis     reaction pathway     equilibrium yield    

Measurement and correlation of the solid-liquid equilibrium of 2-(

Yanhong SUN, Zhiyong LI, Chuang XIE, Wei CHEN, Cui ZHANG

《化学科学与工程前沿(英文)》 2013年 第7卷 第1期   页码 110-115 doi: 10.1007/s11705-013-1316-7

摘要: In this work, the enthalpy of fusion and melting points of 2-( -butyl)-5-methylphenol (2B5MP) and 2-( -butyl)-4-methylphenol (2B4MP) were measured by differential scanning calorimetry (DSC). The binary solid-liquid equilibrium (SLE) of both compounds were predicted by integrated computer aided system (ICAS) and measured by DSC. The corresponding eutectic molar composition is 0.6998 and the eutectic temperature is 281.96 K. The quasi-static heat capacities of 2B5MP and 2B4MP were evaluated by stochastic temperature modulation DSC technique (TOPEM). The SLE experimental data were correlated using the Margules, Wilson, and non-random two liquid (NRTL) equations and a good agreement between measurement and calculation could be obtained.

关键词: solid-liquid equilibrium (SLE)     eutectic     integrated computer aided system (ICAS)     TOPEM     correlation    

Brown marine algae turbinaria conoides as biosorbent for Malachite green removal: Equilibrium and kinetic

R. RAJESH KANNAN, M. RAJASIMMAN, N. RAJAMOHAN, B. SIVAPRAKASH,

《环境科学与工程前沿(英文)》 2010年 第4卷 第1期   页码 116-122 doi: 10.1007/s11783-010-0006-7

摘要: In this study, the biosorption of Malachite green (MG) onto Turbinaria conoides, brown marine algae, was studied with respect to initial pH, temperature, initial dye concentration, and sorbent dosage. The optimum initial pH and temperature values for MG removal were found to be 8.0 and 30°C, respectively. Sorbent dosage was found to strongly influence the removal of MG. Equilibrium studies were carried out to test the validity of the Langmuir ( = 66.6 mg/g and = 0.526 mL mol/L) and the Freundlich ( = 1.826 and = 3.751 mg/g) isotherms. The kinetic studies indicated the validity of the pseudo first-order and second-order equation.

关键词: Malachite green (MG)     Turbinaria conoides     marine algae     equilibrium studies     biosorption    

Non-equilibrium model for catalytic distillation process

WANG Feng, ZHAO Ning, LI Junping, XIAO Fukui, WEI Wei, SUN Yuhan

《化学科学与工程前沿(英文)》 2008年 第2卷 第4期   页码 379-384 doi: 10.1007/s11705-008-0071-7

摘要: A new improved tri-diagonal method was developed for the non-equilibrium stage model of the catalytic distillation by coupling consumptive reaction coefficient. The reactions in the distillation column were divided into generative reaction and consumptive reaction. The non-equilibrium stage model was introduced for the catalytic distillation process of the dimethyl carbonate (DMC) synthesis by urea methanolysis over solid based catalyst, and the improved tri-diagonal method was used to solve the model equations. Comparison of predicted results with experiment data shows that the mean relative error of the yield of DMC was 3.78% under different conditions such as different operating pressures and reaction temperatures. The improved tri-diagonal matrix method could avoid the negative values of the liquid compositions during the calculations and restrain the fluctuation of compositions by slowing down the variations of the values in the iteration. The modeling results show that the improved tri-diagonal method was appropriate for system containing a wide range of boiling point components and a different rate of reactions.

Special issue on “Molecular Sensors and Molecular Logic Gates”

Luling Wu , Tony D. James

《化学科学与工程前沿(英文)》 2022年 第16卷 第1期   页码 1-3 doi: 10.1007/s11705-021-2134-y

Design of bio-oil additives via molecular signature descriptors using a multi-stage computer-aided molecular

《化学科学与工程前沿(英文)》 2022年 第16卷 第2期   页码 168-182 doi: 10.1007/s11705-021-2056-8

摘要: Direct application of bio-oil from fast pyrolysis as a fuel has remained a challenge due to its undesirable attributes such as low heating value, high viscosity, high corrosiveness and storage instability. Solvent addition is a simple method for circumventing these disadvantages to allow further processing and storage. In this work, computer-aided molecular design tools were developed to design optimal solvents to upgrade bio-oil whilst having low environmental impact. Firstly, target solvent requirements were translated into measurable physical properties. As different property prediction models consist different levels of structural information, molecular signature descriptor was used as a common platform to formulate the design problem. Because of the differences in the required structural information of different property prediction models, signatures of different heights were needed in formulating the design problem. Due to the combinatorial nature of higher-order signatures, the complexity of a computer-aided molecular design problem increases with the height of signatures. Thus, a multi-stage framework was developed by developing consistency rules that restrict the number of higher-order signatures. Finally, phase stability analysis was conducted to evaluate the stability of the solvent-oil blend. As a result, optimal solvents that improve the solvent-oil blend properties while displaying low environmental impact were identified.

关键词: computer-aided molecular design     bio-oil additives     molecular signature descriptor    

Progress on molecular biomarkers and classification of malignant gliomas

null

《医学前沿(英文)》 2013年 第7卷 第2期   页码 150-156 doi: 10.1007/s11684-013-0267-1

摘要:

Gliomas are the most common primary intracranial tumors in adults. Anaplastic gliomas (WHO grade III) and glioblastomas (WHO grade IV) represent the major groups of malignant gliomas in the brain. Several diagnostic, predictive, and prognostic biomarkers for malignant gliomas have been reported over the last few decades, and these markers have made great contributions to the accuracy of diagnosis, therapeutic decision making, and prognosis of patients. However, heterogeneity in patient outcomes may still be observed, which highlights the insufficiency of a classification system based purely on histopathology. Great efforts have been made to incorporate new information about the molecular landscape of gliomas into novel classifications that may potentially guide treatment. In this review, we summarize three distinctive biomarkers, three most commonly altered pathways, and three classifications based on microarray data in malignant gliomas.

关键词: malignant glioma     molecular biomarker     IDH1     MGMT     molecular classification    

Molecular classification and molecular targeted therapy of cancer

null

《医学前沿(英文)》 2013年 第7卷 第2期   页码 147-149 doi: 10.1007/s11684-013-0274-2

into nitrogen and sulfur co-doped carbon nanotubes for effective desulfurization of liquid phases: Equilibrium

《环境科学与工程前沿(英文)》 2021年 第15卷 第5期 doi: 10.1007/s11783-021-1397-3

摘要:

• Synthesis of NS-CNTS is used in a high desulfurization performance.

关键词: Dibenzothiophene (DBT)     Tertiary methyl mercaptan     Adsorption     Carbon nano tube (CNT)     Desulfurization     Doping    

分子电子学的发展 Review

Paven Thomas Mathew, 房丰洲

《工程(英文)》 2018年 第4卷 第6期   页码 760-771 doi: 10.1016/j.eng.2018.11.001

摘要:

分子电子学(moletronics)是用分子作为单元对分子电子学器件进行装配。这是一个包含物理、化学、材料科学及工程等学科的多学科交叉领域。分子电子学致力于使硅元件尺寸进一步减小。科学家已经在等效分子器件方面进行了诸多探索性研究。分子电子学在电子以及光子应用中逐渐产生影响,如导电聚合物、光色材料、有机超导体、电致变色材料等。为了满足减小硅片尺寸的需求,研究人员有必要将这种新型技术引入到分子层面。虽然分子层面仪器的实验验证和建模分析是一项艰巨的任务,但分子电子学领域依然出现了突破性进展。本文将对不同分子器件和潜在的适用于不同器件的分子应用结合起来进行讨论,如分子晶体管、分子二极管、分子电容、分子导线和分子绝缘体等。本文简要讨论未来的发展趋势以及介绍各种基于石墨烯已取得一定研究成果的分子仪器。

关键词: 分子电子学     分子晶体管     分子二极管     分子电容器     分子导线     石墨烯    

Molecular size characterization of heavy oil fractions in vacuum and solution by molecular dynamic simulation

Wenpo REN, Honggang CHEN, Chaohe YANG, Honghong SHAN,

《化学科学与工程前沿(英文)》 2010年 第4卷 第3期   页码 250-256 doi: 10.1007/s11705-009-0281-7

摘要: Two kinds of heavy oils were fractionated into eight fractions by Liquid-Solid Adsorption Chromatography, respectively, and samples were collected to measure properties. According to the elemental analysis, molecular weight and H-NMR data, average molecular structures of polycyclic aromatic and heavy resin were constructed with improved Brown-Ladner (B-L) method and several corrections. And then, the most stable conformations of polycyclic aromatic and heavy resin in vacuum and toluene solution were obtained by molecular dynamic simulation, and the molecular size was gotten via the radius of gyration analysis. The results showed that the radius of gyration of polycyclic aromatic and heavy resin was 0.55–0.70 nm in vacuum and 0.60–0.90 nm in toluene solution. With molecular weight increasing, the molecular size in vacuum and toluene solution also increased. Due to the swelling behavior of solvent, the alkyl side chains of heavy oil molecule in solution were more stretched. Thus, the molecular size in toluene solution was larger than that in vacuum.

关键词: dynamic simulation     molecular dynamic     behavior     molecule     Adsorption Chromatography    

标题 作者 时间 类型 操作

Molecular dynamics simulation of diffusivity

LIU Juanfang, ZENG Danling, LI Qin, GAO Hong

期刊论文

A computational toolbox for molecular property prediction based on quantum mechanics and quantitative

期刊论文

Determination of the diffusion of poly(ethylene glycol) in polypropylene using ATR-FTIR

Hanjia CHEN, Xuhua SHI, Yafei ZHU, Yi ZHANG, Jiarui XU,

期刊论文

聚酰胺反渗透膜中水传递阻力的分子模拟——界面阻力和内部阻力

宋阳, 魏明杰, 徐放, 汪勇

期刊论文

Thermodynamic analysis of reaction pathways and equilibrium yields for catalytic pyrolysis of naphtha

期刊论文

Measurement and correlation of the solid-liquid equilibrium of 2-(

Yanhong SUN, Zhiyong LI, Chuang XIE, Wei CHEN, Cui ZHANG

期刊论文

Brown marine algae turbinaria conoides as biosorbent for Malachite green removal: Equilibrium and kinetic

R. RAJESH KANNAN, M. RAJASIMMAN, N. RAJAMOHAN, B. SIVAPRAKASH,

期刊论文

Non-equilibrium model for catalytic distillation process

WANG Feng, ZHAO Ning, LI Junping, XIAO Fukui, WEI Wei, SUN Yuhan

期刊论文

Special issue on “Molecular Sensors and Molecular Logic Gates”

Luling Wu , Tony D. James

期刊论文

Design of bio-oil additives via molecular signature descriptors using a multi-stage computer-aided molecular

期刊论文

Progress on molecular biomarkers and classification of malignant gliomas

null

期刊论文

Molecular classification and molecular targeted therapy of cancer

null

期刊论文

into nitrogen and sulfur co-doped carbon nanotubes for effective desulfurization of liquid phases: Equilibrium

期刊论文

分子电子学的发展

Paven Thomas Mathew, 房丰洲

期刊论文

Molecular size characterization of heavy oil fractions in vacuum and solution by molecular dynamic simulation

Wenpo REN, Honggang CHEN, Chaohe YANG, Honghong SHAN,

期刊论文