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Effects of (BCO)_n Substituent on Claisen Rearrangement of Phenyl Allyl Ether

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Chemical Research in Chinese Universities 2007年第2期23卷 212-216页

作者： PEI Xiao-qin jian jian-feng wu Hai-shun Department of Chemistry Shanxi Normal University Linfen 041004 P. R. China

Considering the isolobal analogy between two fragments CH and BCO, the calculations on the reactants, products, and transition states for the Claisen rearrangement of （BCO）n-substituted phenyl allyl ethers at the B3P86/ 6-311 ＋ G^＊＊ level was performed in this study. The transition states of （BCO）n-substituted systems have looser and more structures with dipole nature. The substitutions of CH by BCO do favor the reduction of the free energies of activation and the enhancement of stabilization of both reactants and products. A Marcus theory and frontier molecular orbitals were used to separate the thermodynamic and intrinsic contributions to the activation energies.

关键词： Transition states Structures Energetics

A Comparative Study on Hydrodynamics and Hydrochemistry Coupled Simulations of Drainage Pipe Crystallization Blockage in Karst Tunnels

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Journal of Earth Science 2022年第5期33卷 1179-1189页

作者： Dian-Guang Liu Yun Yang Cheng-Jun Mao jian-feng wu Ji-Chun wu School of Earth Sciences and Engineering Hohai UniversityNanjing211100China Key Laboratory of Surficial Geochemistry Ministry of EducationDepartment of HydrosciencesSchool of Earth Sciences and EngineeringNanjing UniversityNanjing210023China

Drainage pipe system is the requisite component of the traffic tunnels in Karst *** reveal the dynamic process of crystallization blockage in drainage pipes,a novel hydrodynamics and hydrochemistry coupled simulation model was developed for calculating the deposition rate of CaCO_(3) fouling in pipeline *** adhering to the pipe walls involve a deformable domain with moving geometric boundaries,and moving mesh and level set methods are proposed for simulation of for tunnel turbulence and crystallization fouling *** simulation results are compared with the experimental results showing similar *** effects of temperature,flow velocity,and solution concentration on crystallization blockage were analyzed by comparative simulation *** simulation results show that:(1)the moving mesh method simulated nozzle shrinkage caused by crystalline deposition,without accounting for geometric topology shape ***,the level set method tracked the moving topology and thus can simulate the process of complete blockage;(2)the flow velocity in the longitudinal pipe generally exceeded that in the transverse pipe,and the CaCO_(3) crystal concentration in the transverse pipe eclipsed that in the longitudinal pipe,which meant crystallization blockages primarily occurred in the transverse pipe;(3)the temperature and concentration correlated positively with the crystallization rate,while the crystal precipitation value decreases with the increasing of inlet flow velocity *** study advances a hydrodynamics and hydrochemistry coupled crystallization blockage model to provide technical support for the early identification of crystallizationinduced pipe blockage in the drainage system in karst tunnel sites.

关键词： karst tunnel crystallization blockage numerical simulation moving mesh level set engineering geology

Study of “3-Step Mining” Subsidence Control in Coal Mining Under Buildings

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Journal of China University of Mining and Technology 2007年第3期17卷 316-320页

作者： GUO Guang-li ZHA jian-feng wu Bin JIA Xin-guo School of Environment ＆ Spatial Informatics China University of Mining ＆ Technology Xuzhou jiangsu 221008 China

Mining subsidence damage is the main factor of restricting coal mining under buildings. To control or ease effectively the degree of mining subsidence and deformation is essential to resolve this problem. Through analyzing both advantages and disadvantages of some technologies such as mining with stowing, partial extraction and grouting in separated beds of overburden, we used the principle of load replacement and propose a “3-step mining” method, a new pattern of controlling mining subsidence, which consists of： strip mining, i.e. grouting to fill and consolidate the caving zone and retained strip pillar mining. The mechanism of controlling mining subsidence by using the “3-step mining” pattern is analyzed. The effect of the control is numerically simulated. The preliminary analysis shows that the “3-step mining” can effectively control ground subsidence and deformation. By using this method, the ground subsidence factor can be controlled to a value of about 0.25. Coal recovery can reach 80%-90%. Coal mining without removing surface buildins can be realized and the economic loss resultin from round subsidence can be greatly reduced.

关键词： subsidence control strata movement ground movement mining under buildings

A method of shadow puppet figure modeling and animation

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Frontiers of Information Technology & Electronic Engineering 2015年第5期16卷 367-379页

作者： Xiao-fang HUANG Shou-qian SUN Ke-jun ZHANG Tian-ning XU jian-feng wu Bin ZHU College of Computer Science and Technology Zhejiang University School of Art Zhejiang University of Technology College of Information Science and Technology Zhejiang Shuren University

To promote the development of the intangible cultural heritage of the world, shadow play, many studies have focused on shadow puppet modeling and interaction. Most of the shadow puppet figures are still imaginary,spread by ancients, or carved and painted by shadow puppet artists, without consideration of real dimensions or the appearance of human bodies. This study proposes an algorithm to transform 3D human models to 2D puppet figures for shadow puppets, including automatic location of feature points, automatic segmentation of 3D models, automatic extraction of 2D contours, automatic clothes matching, and animation. Experiment proves that more realistic and attractive figures and animations of the shadow puppet can be generated in real time with this algorithm.

关键词： Shadow play Shadow puppet figure 3D human body Data processing 2D modeling

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World Journal of Gastroenterology 2014年第21期20卷 6457-6469页

作者： Ji Lin jian-feng wu Qi Zhang Hong-Wei Zhang Guang-Wen Cao Department of Epidemiology Second Military Medical University

Chronic infections with hepatitis B virus (HBV) and/or hepatitis C virus (HCV) are the major causes of cirrhosis globally. It takes 10-20 years to progress from viral hepatitis to cirrhosis. Intermediately active hepatic inflammation caused by the infections contributes to the inflammation-necrosis-regeneration process, ultimately cirrhosis. CD8+ T cells and NK cells cause liver damage via targeting the infected hepatocytes directly and releasing pro-inflammatory cytokine/chemokines. Hepatic stellate cells play an active role in fibrogenesis via secreting fibrosis-related factors. Under the inflammatory microenvironment, the viruses experience mutation-selection-adaptation to evade immune clearance. However, immune selection of some HBV mutations in the evolution towards cirrhosis seems different from that towards hepatocellular carcinoma. As viral replication is an important driving force of cirrhosis pathogenesis, antiviral treatment with nucleos(t)ide analogs is generally effective in halting the progression of cirrhosis, improving liver function and reducing the morbidity of decompensated cirrhosis caused by chronic HBV infection. Interferon-α plus ribavirin and/or the direct acting antivirals such as Vaniprevir are effective for compensated cirrhosis caused by chronic HCV infection. The standard of care for the treatment of HCV-related cirrhosis with interferon-α plus ribavirin should consider the genotypes of IL-28B. Understanding the mechanism of fibrogenesis and hepatocyte regeneration will facilitate the development of novel therapies for decompensated cirrhosis.

关键词： Liver cirrhosis Hepatitis B virus Hepatitis C virus Evolution Immune cells Signaling pathway Hepatic stellate cells Antiviral therapy

Characteristics of Momentum and Heat Transfer over Semiarid Grasslands with Different Grazing Intensities in Inner Mongolia,China

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Atmospheric and Oceanic Science Letters 2011年第5期4卷 264-269页

作者： WANG Lei LIU Hui-Zhi Bettina KETZER feng jian-wu Christian BERNHOFER State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry Institute of Atmospherie Physics Chinese Academy of Sciences Beijing 100029 China Institute of Hydrology and Meteorology Chair of Meteorology Technische Universitgit Dresden Tharandt 01737 Germany

The drag coefficient （Ca） and heat transfer coefficient （Ch） with the bulk transfer scheme are usually used to calculate the momentum and heat fluxes in meteorological models. The aerodynamic roughness length （z0m） and thermal roughness length （z0h） are two crucial parameters for bulk transfer equations. To improve the meteorological models, the seasonal and interannual variations of Z0m, Z0h, coefficient kB-1, Cd, and Ch were investigated based on eddy covariance data over different grazed semiarid grasslands of Inner Mongolia during the growing seasons （May to September） from 2005 to 2008. For an ungrazed Leymus chinensis grassland （ungrazed since 1979）, Z0m and z0h had significant seasonal and in- terannual variations. Zorn was affected by the amount and distribution of rainfall, kB 1 exhibited a relatively negative variation compared with z0h, which indicates that the seasonal variation of z0h cannot be described by kB 1. To parameterize Zorn and z0h, the linear regressions between ln（z0m）, ln（z0h）, and the leaf area index （LAI） were performed with R2=0.71 and 0.83. The monthly average kB-1 was found to decrease linearly with LAI. The four-year averaged values of Ca and Ch were 4.5 × 10^-3 and 3.9× 10^-3, respectively. The monthly average Cd only varied by 8% while the variation of Ch was 18%, which reflects the dif- ferent impacts of dead vegetation on momentum and heat transfer at this natural grassland. Moreover, with the removal of vegetation cover, grazing intensities reduced Z0m, Z0h, Cd, and Ch.

关键词： surface roughness length bulk transfer coefficient grazing intensity semiarid grassland

The nature of electron density enhancement over a wide altitude range during ionosphere heating experiments at EISCAT

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Earth and Planetary Physics 2024年第2期8卷 408-414页

作者： Jun wu jian wu Jie feng QingLiang Li ShuJi Hao ZhengWen Xu HaiSheng Zhao YaBin Zhang National Key Laboratory of Electromagnetic Environment China Research Institute of Radio Wave PropagationBeijing 102206China School of Physics Xidian UniversityXi’an 710071China

During the course of ionospheric heating experiments, researchers at the European Incoherent Scatter Scientific Association (EISCAT) observed an apparent electron density enhancement. The enhancement extended over a wide range of altitudes, above the reflection altitude of the high-frequency pump wave. However, whether this enhancement actually corresponds to a true enhancement in electron density remains an open question. When the dispersion relation of ion acoustic waves is followed, the frequency ratio of the enhanced ion line to the background ion line suggests that the profile of the effective ion mass may have remained unchanged. Furthermore, the solar radio flux and ion drift velocity indicate no significant changes in the ion species and their densities. In conclusion, the electron density enhancement observed at EISCAT should not, in fact, be considered a true enhancement.

关键词： incoherent scatter radar(ISR) ionospheric heating electron density ion acoustic wave

Understanding the Thermal Impedance of Silicone Rubber/Hexagonal Boron Nitride Composites as Thermal Interface Materials

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Chinese Journal of Polymer Science 2024年第3期42卷 352-363,I0008页

作者： Yuan Ji Shi-Da Han Hong wu Shao-Yun Guo feng-Shun Zhang jian-Hui Qiu The State Key Laboratory of Polymer Materials Engineering Sichuan Provincial Engineering Laboratory of Plastic/Rubber Complex Processing TechnologyPolymer Research InstituteSichuan UniversityChengdu 610065China Institute of Chemical Materials China Academy of Engineering PhysicsMianyang 621900China Department of Mechanical Engineering Faculty of Systems Science and TechnologyAkita Prefectural UniversityAkita 015-0055Japan

Silicone rubber(SR) composites are most widely used as thermal interface materials(TIMs) for electronics heat dissipation. Thermal impedance as the main bottleneck limiting the performance of TIMs is usually neglected. Herein, the thermal impedance of SR composites loaded with different levels of hexagonal boron nitride(h-BN) as TIMs was elaborated for the first time by the ASTM D 5470 standard test and finite element analysis. It was found that elastic modulus and surface roughness of SR composites increased with the increase of h-BN content, indicating that the conformity was reduced. When the assembly pressure was 0.69 MPa, there existed an optimal h-BN content at which the contact resistance was minimum(0.39 K·cm^(2)·W^(-1)). Although the decreased bond line thickness(BLT) by increasing the assembly pressure was beneficial to reduce the thermal impedance, the proper assembly pressure should be selected to prevent the warpage of the contact surfaces and the increase in contact resistance, according to the compression properties of the SR composites. This study provides valuable insights into fabrication of high-performance TIMs for modern electronic device applications.

关键词： Thermal interface materials Hexagonal boron nitride Thermal impedance Surfaces

Single-atom sites regulation by the second-shell doping for efficient electrochemical CO_(2)reduction

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Chinese Chemical Letters 2024年第9期35卷 360-363页

作者： Qian-Qian Tang Li-Fang feng Zhi-Peng Li Shi-Hao wu Long-Shuai Zhang Qing Sun Mei-feng wu jian-Ping Zou Key Laboratory of jiangxi Province for Persistent Pollutants Control and Resources Recycle Nanchang Hangkong UniversityNanchang 330063China National-Local Joint Engineering Research Center of Heavy Metals Pollutants Control and Resource Utilization Nanchang Hangkong UniversityNanchang 330063China

Nitrogen-doped carbon loaded single-atom catalysts(SACs)are promising candidates for electrocatalytic conversion of CO_(2)into high-valuable chemicals,and the modification of catalysts by heteroatom-doping strategy is an effective approach to enhance the CO_(2)reduction ***,the large difference exists in atomic radius between nitrogen atoms and the doped heteroatoms may lead to the poor stability of active *** this study,we have synthesized a Ni single atom catalyst with S doping at the secondshell on the ultrathin carbon nanosheets support(Ni-N_(4)-SC)by solid-phase *** S atom in the second-shell contributes to the higher efficiency of CO_(2)conversion at lower potentials while the Ni-N_(4)-SC can be more *** experimental results and theoretical calculations indicate that the S atom in second-shell breaks the uniform charge distribution and reduces the free energy of hydrogenation,which can increase the adsorption of CO_(2),accelerate charge transfer,and reduce the reaction energy *** work reveals the close relationship between the second-shell and the electrocatalytic activity of single atom sites,which also provides a new perspective to design efficient single atom catalysts.

关键词： Single-atom catalyst Heteroatom-doping Second shell CO_(2)electroreduction Electronic structure regulation