检索结果-南通市图书馆

DFT Studies on Hydrogen Overfall Mechanism for Catalyzed Hydroisomerization of Pentane

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2007年第2期26卷 239-247页

作者： AI Chun-zhi SUN Ren-An WANG Chang-sheng College of Chemistry and Chemical Engineering Liaoning Normal University Dalian 116029 China Dalian Institute of Chemical Physics The Chinese Academy of Sciences Dalian 116021 China

The mechanism and related reaction paths in the hydroisomerization of n-pentane were studied by DFT calculations at the B3LYP/6-311＋＋G^＊＊ level. Two possible transition states were theoretically predicted and verified by the vibration frequency analysis as well as the calculations of intrinsic reaction coordinates （IRC）. Furthermore, the related reaction barriers were evaluated by single point energy at the MP2/6-311＋＋G^＊＊ level with zero point vibration correction of DFT method. Thus, it is concluded that the isomerization might go through two pathways.

关键词： catalyzed isomerization of n-pentane hydrogen overfall mechanism i-pentane DFT

Active feedback control of sound radiation in elastic wave metamaterials immersed in water with fluid-solid coupling

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2021年第5期37卷 803-825,I0002页

作者： zhi-Hua He Yi-Ze Wang Yue-sheng Wang Institute of Engineering Mechanics Beijing Jiaotong UniversityBeijing 100044China Department of Mechanics Tianjin UniversityTianjin 300350China

Due to their potential properties unlike traditional materials and structures,elastic wave metamaterials have received significant interests in recent *** the coupling between the acoustic and vibration,their mechanical characteristics can be tuned by the active feedback control system at low frequency ranges in which the traditional passive control is *** work illustrates that the superior performances of the effective mass density and sound pressure level(SPL)of an elastic wave metamaterial can be significantly changed by the active control,in which the periodic array of local resonators and orthogonal stiffeners are ***,based on the locally resonant mechanism,the negative density occurs over a frequency *** to the effects of lattice constant,structural damping and other parameters,the SPL with the function of fluid-solid coupling are illustrated and discussed.

关键词： Elastic wave metamaterial Local resonance Sound radiation Fluid-solid coupling Active feedback control

Sound Transmission Comparisons of Active Elastic Wave Metamaterial Immersed in External Mean Flow

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2021年第3期34卷 307-325页

作者： zhi-Hua He Yi-Ze Wang Yue-sheng Wang Institute of Engineering Mechanics Beijing Jiaotong UniversityBeijing 100044China Department of Mechanics Tianjin UniversityTianjin 300350China

Using the active feedback control system on the elastic wave metamaterial,this research concentrates on the sound transmission with the dynamic effective *** metamaterial is subjected to an incident pressure and immersed in the external mean *** elastic wave metamaterial consists of double plates and the upper and lower four-link mechanisms are attached *** vertical resonator is attached by the active feedback control system and connected with two four-link *** on the dynamic equivalent method,the metamaterial is equivalent as a single-layer plate by the dynamic effective *** the coupling between the fluid and structure,the expression of the sound transmission loss(STL)is *** research shows the influence of effective mass density on sound transmission properties,and the STL in both modes can be tuned by the acceleration and displacement feedback *** addition,the dynamic response and the STL are also changed obviously by different values of structural damping,incident angle(i.e.,the elevation and azimuth angles)and Mach number of the external fluid with the mean flow *** results for sound transmission by two methods are compared,i.e.,the virtual work principle for double plates and the dynamic equivalent method corresponding to a single *** paper is expected to be helpful for understanding the sound transmission properties of both pure single-and double-plate models.

关键词： Elastic wave metamaterials Active feedback control Dynamic equivalent method Sound transmission External mean flow

First-principles calculations of structural,elastic and electronic properties of(TaNb)0.67(HfZrTi)0.33 high-entropy alloy under high pressure

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2020年第10期27卷 1405-1414页

作者： zhi-sheng Nong Hao-yu Wang Jing-chuan Zhu School of Materials Science and Engineering Shenyang Aerospace UniversityShenyang 110136China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

To clarify the effect of pressure on a(TaNb)0.67(HfZrTi)0.33 alloy composed of a solid solution with a single body-centered-cubic crystal structure,we used first-principles calculations to theoretically investigate the structural,elastic,and electronic properties of this alloy at different *** results show that the calculated equilibrium lattice parameters are consistent with the experimental results,and that the normalized structural parameters of lattice constants and volume decrease whereas the total enthalpy differenceΔE and elastic constants increase with increasing ***(TaNb)0.67(HfZrTi)0.33 alloy exhibits mechanical stability at high pressures lower than 400 *** high pressure,the bulk modulus B shows larger values than the shear modulus G,and the alloy exhibits an obvious anisotropic feature at pressures ranging from 30 to 70 *** analysis of the electronic structures reveals that the atomic orbitals are occupied by the electrons change due to the compression of the crystal lattices under the effect of high pressure,which results in a decrease in the total density of states and a wider electron energy *** factor is favorable for zero resistance.

关键词： first-principles calculations elastic property electronic structure density of states high-entropy alloys high pressure

Reduction of NO_(x)emission based on optimized proportions of mill scale and coke breeze in sintering process

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2021年第9期28卷 1453-1461页

作者： zhi-gang Que Xian-bin Ai sheng-li Wu Institute of Energy Research Jiangxi Academy of ScienceNanchang 330096China School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China

Reducing NO_(x) emission of iron ore sintering process in a cost effective manner is a challenge for the iron and steel industry at *** of the proportion of mill scale and coke breeze on the NO_(x) emission,strength of sinter,and sinter indexes were studied by com-bustion and sinter pot *** showed that the peak value of NO concentration,total of NO emission,and fuel-N conversion rate gradu-ally decreased as the proportions of the mill scale increased because NO was reduced to N_(2) by Fe_(3)O_(4),FeO,and Fe in the mill *** strength of sinter reached the highest value at 8.0wt%mill scale due to the formation of minerals with low melting *** fuel-N conver-sion rate slightly fluctuated and total NO_(x) emission significantly decreased with the decreased proportions of coke breeze because CO forma-tion and content of N element in the sintered mixture ***,the sinter strength also decreased due to the decrease in the amount of the melting ***,results of the sinter pot tests indicated that NO_(x) emission *** sinter indexes performed well when the proportions of mill scale and coke breeze were 8.0wt%and 3.70wt%respectively in the sintered mixture.

关键词： iron ore sinter NO_(x)emission mill scale coke breeze proportion optimization

Palladium and carbon synergistically catalyzed room-temperature hydrodeoxygenation(HDO) of vanillyl alcohol–A typical lignin model molecule

在线全文

学校读者我要写书评

暂无评论

Journal of Energy Chemistry 2017年第1期26卷 8-16页

作者： Qi Wang Neeraj Gupta Guodong Wen Sharifah Bee Abd Hamid dang sheng Su School of Materials Science and Engineering University of Science and Technology of China Institute of Metal Research Chinese Academy of Sciences Nanotechnology & Catalysis Research Centre (NANOCAT) University of Malaya IPS Building

Vanillyl alcohol, which is made up of an aromatic ring, an alcoholic hydroxyl group, a phenolic hydroxyl group and a methoxy group, was selected as the model molecule of lignin. Various carbon materials supported Pd catalysts were chosen to catalyze the HDO of vanillyl alcohol. The catalysts were characterized via TEM, TPD, XRD, XPS and CO-chemisorption. It was found that different carbon materials could obviously influence the particle sizes, dispersion and distribution of Pd or PdO particles. Palladium and carbon can synergistically catalyze the room-temperature HDO of vanillyl alcohol even at room temperature, and the carboxyl group was found to be the effective active acid site during the reaction. Possible reaction mechanism was also proposed. The existence of the effective active acid sites on the carbon supports could obviously lower the reaction temperature without decreasing the selectivity, as a result, making the production of renewable fuels by HDO much more economically feasible, which is of much importance. © 2016 Science Press

关键词： Bioconversion Carbon Catalysts Dispersions Molecules Palladium

Targeting methyltransferase-like 5-mediated sphingomyelin metabolism:A novel therapeutic approach in gastric cancer

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastrointestinal Oncology 2024年第10期16卷 4060-4063页

作者： Jin-Juan Zhang Chang Yuan sheng-Chun dang Department of General Surgery The Affiliated Hospital of Jiangsu UniversityZhenjiang 212001Jiangsu ProvinceChina

Gastric cancer(GC)is a global health problem and a leading cause of cancerrelated deaths,with its mortality rate ranking third among all *** etiology and progression of GC are characterized by a complex interplay of genetic and epigenetic changes,which present challenges for its early diagnosis and effective *** the mechanisms underlying the occurrence and development of GC and identifying novel biomarkers for early detection and prognosis are crucial to improving patient *** editorial examines the role of methyltransferase-like 5(METTL5)in the progression of GC through sphingomyelin metabolism by considering an article published by Zhang et al in the World Journal of Gastrointestinal Oncology in 2024,which is entitled“METTL5 promotes GC progression via sphingomyelin metabolism”.These authors investigated the biological behavior of METTL5 in GC by examining its expression patterns,clinical relevance,functional effect,and potential mechanisms,as well as its response to *** editorial provides valuable insights into the role of METTL5 in the progression of GC and its potential as a therapeutic target.

关键词： Gastric cancer Methyltransferase-like 5 Sphingomyelin metabolism Biomarkers Chemotherapy response

Comparison between uncut Roux-en-Y and Roux-en-Y reconstruction after distal gastrectomy for gastric cancer: A meta-analysis

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2018年第24期24卷 2628-2639页

作者： Ming-Ming Sun Yi-Yi Fan sheng-Chun dang Department of General Surgery The Affiliated Hospital of Jiangsu University

AIM To compare uncut Roux-en-Y(U-RY) gastrojejunostomy with Roux-en-Y(RY) gastrojejunostomy after distal gastrectomy(DG) for gastric *** A literature search was conducted in Pubmed, Embase, Web of Science, Cochrane Library, Science Direct, Chinese National Knowledge Infrastructure, Wanfang, and China Science and Technology Journal Database to identify studies comparing U-RY with RY after DG for gastric cancer until the end of December 2017. Pooled odds ratio or weighted mean difference with 95% confidence interval was calculated using either fixed-or random-effects models. Perioperative outcomes such as operative time, intraoperative blood loss, and hospital stay; postoperative complications such as anastomotic bleeding, stricture and ulcer, reflux gastritis/esophagitis, delayed gastric emptying, and Roux stasis syndrome; and postoperative nutritional status(serum hemoglobin, total protein, and albumin levels) were the main outcomes assessed. Metaanalyses were performed using RevM an 5.3 *** Two randomized controlled trials and four nonrandomized observational clinical studies involving 403 and 488 patients, respectively, were included. The results of the meta-analysis showed that operative time [weighted mean difference(WMD):-12.95; 95%CI:-22.29 to-3.61; P = 0.007] and incidence of reflux gastritis/esophagitis(OR: 0.40; 95%CI: 0.20-0.80; P = 0.009), delayed gastric emptying(OR: 0.29; 95%CI: 0.14-0.61; P = 0.001), and Roux stasis syndrome(OR: 0.14; 95%CI: 0.04-0.50; P = 0.002) were reduced; and the level of serum albumin(WMD: 0.71; 95%CI: 0.24-1.19; P = 0.003) was increased in patients undergoing U-RY reconstruction compared with those undergoing RY reconstruction. No differences were found with respect to intraoperative blood loss, hospital stay, anastomotic bleeding, anastomotic stricture, anastomotic ulcer, the levels of serum hemoglobin, and serum total protein. CONCLUSION U-RY reconstruction has some clinical advantages over RY reconstru

关键词： Roux-en-Y Gastric cancer Meta-analysis Distal gastrectomy Reconstruction Uncut

Theoretical analysis and application of polymer-matrix field grading materials in HVDC cable terminals

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

High Voltage 2017年第1期2卷 39-46页

作者： Peng Han Jun-Wei Zha Si-Jiao Wang zhi-Min dang Department of Polymer Science and Engineering University of Science and Technology BeijingBeijing 100083People’s Republic of China State Key Laboratory of Power System and Department of Electrical Engineering Tsinghua UniversityBeijing 100084People’s Republic of China

The distortion and uneven distribution of electric field in high-voltage direct current(HVDC)terminal insulator is the key problem for stable running of the power transmission *** flexible materials filled polymer-matrix composites with non-linear conductivity have also been considered to modify the distribution of electric field in cable *** factors having influence on the non-linear conductivity will be analysed in this review.

关键词： field conductivity matrix