检索结果-南通市图书馆

Influence of Fabrication Parameters on the Phase Formation and Dielectric Properties of CaCu_3Ti_4O_(12 )Ceramics

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2012年第10期28卷 920-926页

作者： qian zheng Huiqing Fan State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytech-nical UniversityXi'an 710072China

The giant dielectric permittivity materials CaCu3Ti4012 （CCTO） were synthesized by conventional solid-state reaction techniques. X-ray diffraction and Raman scattering for the powder indicate that the powder calcined at 950 ℃ for 12 h has been completely transformed into the purer CCTO phase. Furthermore, the morphology and size of the grains of the ceramics sintered at 1090 ℃ in the dwell time range from 0 to 26 h were observed by scanning electron microscopy （SEM）. Dielectric properties of the polycrystalline CCTO ceramics were characterized in a broad frequency range （100 Hz-1 MHz） and at a temperature ranged from 300 to 500 K. The longer sintering time may lead to more defect structures and the enhanced conductivity, also leads to substantial improvements in permittivity. Grain size and density differences were not large enough to account for the enhancement in dielectric permittivity. Based on the observations, it is believed that the primary factor affecting dielectric behavior is the development of internal defects. The CCTO ceramics sintered at 1090 ℃ for 15 h exhibit lower dielectric loss （-0.05） near room temperature, and the dielectric relaxation behavior above 1 kHz was observed to follow the Arrhenius law. The activation energy （Ea） of 0.65 eV indicates that the doubly ionized oxygen vacancies in the grain boundaries are responsible for the dielectric relaxation of the CCTO ceramics.

关键词： Microstructure Dielectric properties Impedance spectroscopy Relaxation

在线全文

学校读者我要写书评

暂无评论

熊果酸干预人牙周膜干细胞成骨分化的效应

中国组织工程研究 2025年第1期29卷 80-86页

作者：郑茜刘萍萍顾煜婕谢蕾西南医科大学附属口腔医院正畸科四川省泸州市646000 口颌面修复重建和再生泸州市重点实验室四川省泸州市646000 南充市中心医院口腔科四川省南充市637000 西南医科大学附属口腔医院城北门诊部四川省泸州市646000

背景:熊果酸可促进骨髓间充质干细胞向成骨细胞定向分化,但其对人牙周膜干细胞是否具有促成骨作用目前相关报道少见。目的:探讨熊果酸对人牙周膜干细胞增殖和成骨分化能力的影响。方法:分离、培养人牙周膜干细胞,取第3代细胞,分别采用... 详细信息

背景:熊果酸可促进骨髓间充质干细胞向成骨细胞定向分化,但其对人牙周膜干细胞是否具有促成骨作用目前相关报道少见。目的:探讨熊果酸对人牙周膜干细胞增殖和成骨分化能力的影响。方法:分离、培养人牙周膜干细胞,取第3代细胞,分别采用含不同浓度(0,1,2,4,6,8μmol/L)熊果酸的普通培养基干预,干预1,3,5,7 d后,采用CCK-8法检测细胞增殖,筛选适宜干预浓度。取第3代人牙周膜干细胞,分别用含0,1,2,4μmol/L熊果酸的成骨诱导液干预,干预7 d后,采用qRT-PCR法检测碱性磷酸酶、Runx2、骨钙素m RNA的表达,干预14 d后,茜素红染色观察矿化结节形成。取第3代人牙周膜干细胞,对照组加入成骨诱导液,熊果酸组、拮抗剂组分别加入含熊果酸(2μmol/L)、骨形态发生蛋白信号通路拮抗剂Noggin的成骨诱导液,熊果酸+拮抗剂组加入含熊果酸(2μmol/L)、骨形态发生蛋白信号通路抑制剂Noggin的成骨诱导液,培养7 d后,采用qRT-PCR和Western blot检测骨形态发生蛋白2、Smad1、骨桥蛋白、Runx2的m RNA及蛋白表达。结果与结论:(1)1,2,4μmol/L熊果酸可促进人牙周膜干细胞的增殖,6,8μmol/L熊果酸可抑制人牙周膜干细胞的增殖,后续实验选择1,2,4μmol/L熊果酸进行干预;(2)与0μmol/L相比,1,2,4μmol/L熊果酸可促进碱性磷酸酶、Runx2、骨钙素m RNA的表达以及矿化结节的形成(P<0.05),其中以2μmol/L熊果酸效果最显著;(3)与对照组比较,熊果酸组骨形态发生蛋白2、Smad1、骨桥蛋白、Runx2的mRNA及蛋白表达均升高(P<0.05),拮抗剂组上述指标的mRNA及蛋白表达均降低(P<0.05);与熊果酸组比较,熊果酸+拮抗剂组上述指标的mRNA及蛋白表达均降低(P<0.05);(4)结果表明,熊果酸可通过激活骨形态发生蛋白信号通路促进人牙周膜干细胞的成骨分化。

关键词：人牙周膜干细胞熊果酸成骨骨形态发生蛋白信号通路碱性磷酸酶骨钙素骨形态发生蛋白2 Smad1蛋白

Linearizing the soft finger contact constraint with application to dynamic force distribution in multifingered grasping

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2005年第2期48卷 121-130页

作者： zheng Yu qian Wenhan Robotics Institute Shanghai Jiao Tong University Shanghai 200030 China Robotics Institute Shanghai Jiao Tong University Shanghai 200030 China

Currently, most efficient algorithms for force-closure analysis and dynamic force distribution utilize linear programming, but friction models are nonlinear. Substituting polyhedral cones for circular cones of Coulomb friction realizes the linearization of the frictional point contact constraint. So far, however, there is no approach to soft finger contact. This paper present such an approach. Then the foregoing algorithms can be extended to grasping with soft finger contact. Herein an optimal force distribution algorithm for soft multifingered grasps is developed with an illustrative example.

关键词： multifingered grasping, soft finger contact, linearization, force-closure, dynamic force distribution (DFD).

EXPERIMENTAL STUDY AND APPLICATION OF VIBROFLOTATION METHOD AT SEA BOTTOM

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 1990年第3期5卷 329-344页

作者： qian, zheng Luo, Zongxin Tianjin Port Engineering Inst Tianjin China

The vibroflotation technique has now become a comparatively perfect method. However, the stone column driving at the sea bottom, which is liable to ebb and flood tides, is seldom tried abroad and has been tried for the first time at home. We have designed a set of construction techniques for driving and installing stone columns at sea. These techniques have been proved successful and highly efficient by practice. At the sea bottom were conducted three groups of large-scale loading tests and the allowable bearing capacity of the composite foundation was obtained as 130 kPa, against that of the natural foundation: 50 kPa. The allowable bearing capacity of the composite foundation showed 2.6 times as much as that of the natural foundation. Also obtained was the distribution ratio of stress, n = 3. The experience and indexes, obtained from the Yantai Harbour Project, have already been justified in the application in reinforcing the coastal highway at the Huaneng Power Plant of Fuzhou City, Fujian Province.

关键词： Foundations Bearing Capacity Oceanography Ports and Harbors

Flexible,Light-Interacting,B-Shaped Structures for Computations

在线全文

学校读者我要写书评

暂无评论

Research 2023年第4期2023卷 453-462页

作者： Nan Yang zheng qian Huaxian Wei Yubo Zhang Intelligent Manufacturing Key Laboratory of the Ministry of Education College of EngineeringShantou UniversityShantou 515063China

Integrating mechanical computing functions into robotic materials,microelectromechanical systems,or soft robotics can improve their intelligence in stimulation-response *** mechanical computing systems exhibit limitations,including incomplete functions,unchangeable computing rules,difficulties in realizing random logic,and lack of *** overcome these limitations,we propose a straightforward method of designing mechanical computing systems—based on the logic expressions—for complex *** designed soft,B-shaped mechanical metamaterial units,and compressed them to render stress inputs;the outputs are represented by the light-shielding effects caused by the unit *** realized logic gates and corresponding combinations(including half/full binary adder/subtractor and addition/subtraction of 2 numbers with multiple bits)and provided a versatile solution for making a mechanical analog-to-digital converter to generate both ordered and disordered *** performed all of the computations within the elastic regions of the B-shaped units;thus,after one computation,the systems can return to the initial states for *** proposed mechanical computers will potentially enable robotic materials,microelectromechanical systems,or soft robotics to perform complex ***,one can extend this concept to systems that are based on other mechanisms or materials.

关键词： shaped limitations return

Prediction of thermal fatigue life of a turbine nozzle guide vane

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 Zhejiang University-Science A(Applied Physics & Engineering) 2011年第3期12卷 214-222页

作者： Xin-qian zheng Tao DU Yang-jun ZHANG State Key Laboratory of Automotive Safety and Energy Tsinghua University Beijing 100084 China Bering Power Macklnery Research Institute Beijing 100074 China

Thermal fatigue (TF) is one of the most important factors that influence turbine's *** paper establishes a 3D solid-fluid coupling model for a steady temperature analysis of a high-pressure turbine nozzle at different turbine inlet gas total temperatures (TIGTTs).The temperature analysis supplies the temperature load for subsequent 3D finite element analysis to obtain the strain *** this,the prediction of the TF life is made on the basis of equivalent strain *** results show that the strain increases with TIGTT,and the predicted TF life decreases *** life prediction was confirmed by one TF test.

关键词： Engine Nozzle guide vane Thermal fatigue (TF) life Solid-fluid

Worldwide rapeseed (Brassica napus L.) research:A bibliometric analysis during 2011–2021

在线全文

学校读者我要写书评

暂无评论

Oil Crop Science 2022年第4期7卷 157-165页

作者： qian zheng Kede Liu Library of Huazhong Agricultural University HubeiPR China National Key Laboratory of Crop Genetic Improvement Huazhong Agricultural UniversityWuhanPR China

Rapeseed(Brassica napus L.) is the world?s second produced oilseed and accounts for nearly 12% of world major vegetable oil *** the last 10 years,the production,planting area,and yield of rapeseed have been stable,with improvement of seed quality and especially seed oil *** paper presented the worldwide rapeseed research by using the bibliometric analysis of papers published during the period 2011–*** total,7617 articles and reviews were included in this *** results showed that the global publication on rapeseed increased substantially in the past 11 years,and the number of publications of China grew significantly in *** was the largest contributor to rapeseed research with higher H-index value and number of citations compared to the other *** also had the largest number of leading universities and institutions,of which Huazhong Agricultural University was the most *** scientific mapping including co-authorship network of countries/regions and authors,and co-occurrence network of author keywords were analyzed using VOSviewer *** most common rapeseed research topics included oil,rapeseed meal,yield,biodiesel,fatty acids,salt stress,and proteins,while the current research focused on topics such as:abiotic stress,evolution,expression analysis,phylogenetic analysis,heterosis,polyploidy,and *** paper depicts the knowledge structure of current global rapeseed research that may help direct the future studies for relevant researchers.

关键词： Rapeseed Brassica napus L. Bibliometric analysis Performance analysis Scientific mapping

Summary study of data-driven photometric stereo methods

在线全文

学校读者我要写书评

暂无评论

Virtual Reality & Intelligent Hardware 2020年第3期2卷 213-221页

作者： qian zheng Boxin SHI Gang PAN School of Electrical and Electronic Engineering Nanyang Technological UniversitySingapore National Engineering Laboratory for Video Technology Department of CSPeking UniversityBeijing 100871China State Key Lab of CAD&CG College of Computer Science and TechnologyZhejiang UniversityHangzhou 310058China

Background A photometric stereo method aims to recover the surface normal of a 3D object observed under varying light *** is an ill-defined problem because the general reflectance properties of the surface are *** This paper reviews existing data-driven methods,with a focus on their technical insights into the photometric stereo *** divide these methods into two categories,per-pixel and all-pixel,according to how they process an *** discuss the differences and relationships between these methods from the perspective of inputs,networks,and data,which are key factors in designing a deep learning *** We demonstrate the performance of the models using a popular benchmark *** Data-driven photometric stereo methods have shown that they possess a superior performance advantage over traditional ***,these methods suffer from various limitations,such as limited generalization ***,this study suggests directions for future research.

关键词： Photometric stereo Data-driven methods Non-Lambertian reflectance

Effect of enhanced recovery after surgery with multidisciplinary collaboration on nursing outcomes after total knee arthroplasty

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

World Journal of Clinical Cases 2023年第32期11卷 7745-7752页

作者： Jing Liu qian-qian zheng Yang-Tao Wu Operating Room Shangrao People's HospitalShangrao 334000Jiangxi ProvinceChina

BACKGROUND There is a lack of studies on the effects of enhanced recovery after surgery(ERAS)with multidisciplinary collaboration on the nursing outcomes of total knee arthroplasty(TKA).AIM To explore the effect of ERAS with multidisciplinary collaboration on nursing outcomes after *** We retrospectively analyzed the clinical data of 80 patients who underwent TKA at a tertiary hospital between January 2021 and December *** patients were divided into two groups according to the nursing mode:the ERAS group(n=40)received ERAS with multidisciplinary collaboration,and the conventional group(n=40)received routine *** following indicators were compared between the two groups:length of hospital stay,hospitalization cost,intraoperative blood loss,hemoglobin level 24 h after surgery,visual analog scale(VAS)score for pain,range of motion(ROM)of the knee joint,Hospital for Special Surgery(HSS)knee score,and postoperative *** The ERAS group had a significantly shorter length of hospital stay,lower hospitalization cost,less intraoperative blood loss,higher hemoglobin level 24 h after surgery,lower VAS score for pain,higher knee joint ROM,and higher HSS knee score than the conventional group(all P0.05).CONCLUSION Multidisciplinary collaboration with ERAS can reduce blood loss,shorten hospital stay,and improve knee function in patients undergoing TKA.

关键词： Arthroplasty,replacement,knee Retrospective studies Range of motion,articular Length of stay Blood loss,surgical Hemoglobins