检索结果-南通市图书馆

Structure Prediction Based on hydrophobic to hydrophilic Volume Ratios in Small Molecule Amphiphilic Organic Crystals

在线全文

学校读者我要写书评

暂无评论

Chinese journal of Structural Chemistry 2002年第6期21卷 592-596页

作者： zheng－TaoXu StephenLee DepartmentofChemistryandChemicalBiology BakerLaboratoryCornellUniversityIthacaNY14853－1301 Authortowhomcorrespondenceshouldbeaddressed

The structure type for the crystal of 4,4'-bis-(2-hydroxy-ethoxyl)-biphenyl 1 has been predicted by using the previously developed interfacial model for small organic molecules. Based on the calculated hydrophobic to hydrophilic volume of 1, this model predicts the crystal structure to be of lamellar or bicontinuous type, which has been confirmed by the X-ray single-crystal structure analysis (C20h26O6, monoclinic, P21/C, a = 16.084(1), b = 6.0103(4), c = 9.6410(7) A, β9 = 103.014(2)°, V= 908.1(1) A3, Z = 2, Dc= 1.325 g/cm3, F(000)=388,μ = 0.097 mm-1, MoKα radiation, λ = 0.71073 A, R = 0.0382 and wR = 0.0882 with I > 2σ(I) for 7121 reflections collected, 1852 unique reflections and 170 parameters). As predicted, the hydrophobic and hydrophilic portions of 1 form in the lamellae. The same interfacial model is applied to other amphilphilic small molecule organic systems for structural type prediction.

关键词： amphiphilic system minimal surface organic crystal structure prediction

Categorical computation

在线全文

学校读者我要写书评

暂无评论

Frontiers of physics 2023年第2期18卷 181-187页

作者： Liang Kong hao zheng Shenzhen Institute for Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China International Quantum Academy Shenzhen 518048China Guangdong Provincial Key Laboratory of Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Institute for Applied Mathematics Tsinghua UniversityBeijing 100084China Beijing Institute of Mathematical Sciences and Applications Beijing 101408China Department of Mathematics Peking UniversityBeijing 100871China

In quantum computing, the computation is achieved by linear operators in or between hilbert spaces. In this work, we explore a new computation scheme, in which the linear operators in quantum computing are replaced by (higher) functors between two (higher) categories. If from Turing computing to quantum computing is the first quantization of computation, then this new scheme can be viewed as the second quantization of computation. The fundamental problem in realizing this idea is how to realize a (higher) functor physically. We provide a theoretical idea of realizing (higher) functors physically based on the physics of topological orders.

关键词： quantum computation categorical computation topological order

homotopy analysis solutions for the asymmetric laminar flow in a porous channel with expanding or contracting walls

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2011年第2期27卷 208-214页

作者： X.-h. Si L.-C. zheng X.-X. Zhang Y. Chao Applied Science School University of Science and Technology Beijing 100083 Beijing China Department of Mechanical Engineering University of Science and Technology Beijing100083 Beijing China Research Institute of Chemical Defense of the EL.A 102205 Beijing China

In this paper, the asymmetric laminar flow in a porous channel with expanding or contracting walls is investigated. The governing equations are reduced to ordinary ones by using suitable similar transformations. homotopy analysis method （hAM） is employed to obtain the expres- sions for velocity fields. Graphs are sketched for values of parameters and associated dynamic characteristics, especially the expansion ratio, are analyzed in detail.

关键词： homotopy analysis method · Expanding or contracting wall · Asymmetric laminar flow · Porous channel · Expansion ratio

Prediction of dispersed phase holdup in pulsed disc and doughnut solvent extraction columns under different mass transfer conditions

在线全文

学校读者我要写书评

暂无评论

Chinese journal of Chemical Engineering 2016年第2期24卷 226-231页

作者： Yong Wang Kathryn h.Smith Kathryn Mumford Teobaldo F.Grabin zheng Li Geoffrey W.Stevens Particulate Fluids Processing Centre Department of Chemical and Biomolecular EngineeringThe University of Melbourne

Using experimental data from a number of pulsed disc and doughnut solvent extraction columns, a unified correla- tion for the prediction of dispersed phase holdup that considers the effects of mass transfer is presented. Pulsed disc and doughnut solvent extraction columns （PDDC） have been used for a range of important applications such as ura- nium extraction and nuclear fuel recycling. Although the dispersed phase holdup in a PDDC has been presented by some researchers, there is still the need to develop a robust correlation that can predict the experimental dispersed phase holdup over a range of operating conditions including the effects of mass transfer direction. In this study, dis- persed phase holdup data from different literature sources for a PDDC were used to refit constants for the correlation presented by Kumar and hartland lind. Eng. Chem. Res.,27 （1988）,131-138] which did not consider the effect of col- umn geometry. In order to incorporate the characteristic length of the PDDC （i.e. the plate spacing）, the unified cor- relation for holdup proposed by Kumar and hartland based on data from eight different types of columns [Ind. Eng. Chem. Res.,34 （1995） 3925-3940] was refitted to the PDDC data. New constants have been presented for each hold- up correlation for a PDDC based on regression analysis using published holdup data from PDDCs that cover a range of onerating conditions and nhwical nronerties and consider the direction of mass transfer.

关键词： Solvent extraction Liquid extraction Pulsed disc and doughnut columns Solvent extraction column design holdup Dispersed phase holdup hydrodynamics of extraction columns

Inorganic Nanotube/Organic Nanoparticle hybrids for Enhanced Photoelectrochemical Properties

在线全文

学校读者我要写书评

暂无评论

journal of Materials Science & Technology 2017年第7期33卷 728-733页

作者： Yingzhi Chen Aoxiang Li Ming jin Lu-Ning Wang zheng-hong huang Key Laboratory of Advanced Materials （MOE） School of Materials Science and Engineering Tsinghua University Beijing 100084 China

Inorganic/organic nanohybrids composed of arrayed TiO_2 nanotubes（Ti NTs）/porphyrin nanoparticles（NPs） have been fabricated via a wet chemical approach. The inorganic component, particularly the arrayed one-dimensional（1D） nanostructures, provides high charge-carrier mobility and rapid charge transport. The organic component exhibits extensive visible light absorption and good solution processability. Additionally, the geometric restraint by supramolecular assembly renders an improved photostability. A combination of these two components could thus allow for an efficient solar energy conversion. In this work, a colloid of porphyrin NPs prepared by a solvent exchange method is coated on anodic Ti NTs by means of a dip-coating treatment to form inorganic/organic hybrids. The hybrids exhibit an improvement on solar absorption and a significant enhancement on photocurrent generation at a small bias compared with individual component. herein, the inorganic/organic nanohybrids are proved to be excellent photoanodes highly responsive to visible light and thus pave a way to discover new inorganic/organic assemblies for high-performance optoelectronic applications, as well as for device integration.

关键词： Anodic TiO_2 nanotubes Porphyrin nanoparticles Inorganic/organic nanohybrid Photoelectrochemical water splitting

STUDY ON ThE PROPERTIES OF DIFFERENT ACTIVATED CARBON FIBERS AND ThEIR ADSORPTION ChARACTERISTICS FOR FORMALDEhYDE

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2001年第6期14卷 467-472页

作者： h.Q. Rong, Z.Y. Ryu and j.T. zheng (Institute of Coal Chemistry, The Chinese Academy of Sciences, P.O.Box 165, Taiyuan 030001, China) Inst. of Coal Chem. Chinese Acad. of Sci. Taiyuan 030001 P.O. Box 165 China

Porous structure and surface chemistry of activated carbon fibers obtained by differ-ent precursors and activation methods were investigated. Adsorption isotherms werecharacterized by nitrogen adsorption at 77K over a relative pressure range from 10 6to 1. The regularization method according to Density Functional Theory (DFT) wasemployed to calculate the pore size distribution in the samples. Their specific surfaceareas were calculated by BET method, micropore volume and microporous specificsurface area calculated by t-plot method and MPD by horvath-Kawazoe equation. Mi-cropore volume of rayon-based ACF was higher than that of other samples. The staticand dynamic adsorption capacity for formaldehyde on different ACFs was *** results show that steam activated Rayon-based A CFs had higher adsorption capac-ity than that of steam and KOh activated PAN-A CFs. Breakthrough curves illustratedthat Rayon-ACFs had longer breakthrough time, thus they possessed higher adsorp-tion capacity for formaldehyde than that of PAN-ACFs. The entire sample had smalladsorption capacity and short breakthrough time for water. Rayon-A CFs had exccl-lent adsorption selectivity for formaldehyde than PAN-ACFs. And the samples withhigh surface areas had relatively high adsorption capacity for formaldehyde. Elementaicontent of different A CFs were performed. Rayon-based A CFs contained more oxygenthan PAN-ACFs, which may be attributed to their excellent adsorption capacity forformaldehyde.

关键词： activated carbon fiber porous structure surface chemistry formaldehyde adsorption characteristic

Ultrafine Sn nanocrystals in a hierarchically porous N-doped carbon for lithium ion batteries

在线全文

学校读者我要写书评

暂无评论

Nano Research 2017年第6期10卷 1950-1958页

作者： Xinghua Chang Teng Wang Zhiliang Liu Xinyao zheng jie zheng Xingguo Li Beijing National Laboratory for Molecular Sciences (BNLMS) College of Chemistry and Molecular Engineering Peking University Beijing 100871 China Academy for Advanced Interdisciplinary Studies Peking University Beijing 100871 China

We report a simple method of preparing a high performance, Sn-based anode material for lithium ion batteries （LIBs）. Adding h2O2 to an aqueous solution containing Sn2＋ and aniline results in simultaneous polymerization of aniline and oxidation of Sn2＋ to SnO2, leading to a homogeneous composite of polyaniline and SnO2. hydrogen thermal reduction of the above composite yields N-doped carbon with hierarchical porosity and homogeneously distributed, ultrafine Sn particles. The nanocomposite exhibits excellent performance as an anode material for lithium ion batteries, showing a high reversible specific capacity of 788 mAh·g^-1 at a current density of 100 mA·g^-1 after 300 cycles and very good stability up to 5,000 mA·g^-1. The simple preparation method combined with the good electro- chemical performance is highly promising to promote the application of Sn based anode materials.

关键词： Sn polyaniline nanocomposite lithium ion battery (LIB)

AN h-BASED A- φMEThOD WITh A NONMATChING GRID FOR EDDY CURRENT PROBLEM WITh DISCONTINUOUS COEFFICIENTS

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

journal of Computational Mathematics 2004年第6期22卷 881-894页

作者： TongKang zheng-pengWu De-haoYu DepartmentofAppliedMathematics SchoolofSciencesBeijingBroadcastingInstituteBeijing100024China ICMSEC AcademyofMathematicsandSystemSciencesChineseAcademyofSciencesBeijing100080China LSEC ICMSECAcademyofMathematicsandSystemSciencesChineseAcademyofSciencesBeijing100080China

In this paper, we investigate the finite element A-φ method to approximate the eddy current equations with discontinuous coefficients in general three-dimensional Lipschitz polyhedral eddy current region. Nonmatching... 详细信息

关键词： Eddy current problem Finite element A method Nonmatching meshes Error estimates

Molecular characterization of polar heteroatom species in oilsands bitumen-derived vacuum residue fractions by Fourier transform ion cyclotron resonance mass spectrometry

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petroleum Science 2019年第5期16卷 1196-1207页

作者： Fang zheng Warren Chung Eusebio Palmisano Dahai Dong Quan Shi Zhiming Xu Keng h.Chung State Key Laboratory of heavy Oil Processing China University of PetroleumBeijing 102249China Well Resources Inc EdmontonCanada Cenovus Energy Inc CalgaryCanada Qingdao Institute of Bioenergy and Bioprocess Technology Chinese Academy of SciencesQingdao 266101China

A Canadian in situ oilsands bitumen-derived vacuum residue(VR)was subjected to supercritical fluid extraction and fractionation(SFEF)into 13 extractable fractions and an unextractable end-cut and characterized by positive-and negative-ion electrospray ionization(ESI)Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS).The results of negative-ion ESI FT-ICR MS showed that the N1 class species was the most abundant and the multifunctional group compounds,such as N1 O1,N1 O2,N1 S1,N1 S2,and N2 class species became abundant as the SFEF fraction became *** positive-ion ESI mode,the relative abundance of N1 class species decreased gradually in the heavy SFEF fractions while that of multifunctional group compounds *** relative abundance of N4 V1 O1 increased dramatically in heavy fractions and the *** distributions of polar heteroatom species of VR derived from oilsands bitumen were similar with those of VR derived from the Venezuela Orinoco extra heavy oil.

关键词： Molecular characterization Canadian oilsands bitumen SFEF ESI FT-ICR MS