检索结果-南通市图书馆

A Novel Multiscale Reinforcement by In-Situ Growing Carbon Nanotubes on Graphene Oxide Grafted Carbon Fibers and Its Reinforced Carbon/Carbon Composites with Improved Tensile Properties

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2016年第5期32卷 419-424页

作者： Yunyu li ling-jun Guo Ya-wen Wang he-jun li Qiang Song State Key Laboratory of Solidification Processing Northwestern Polytechnical University Center for Nano Energy Materials Northwestern Polytechnical University

In-situ growing carbon nanotubes （CNTs） directly on carbon fibers （CFs） always lead to a degraded tensile strength of CFs and then a poor fiber-dominated mechanical property of carbon/carbon composites （C/ Cs）. To solve this issue, here, a novel carbon fiber-based multiscale reinforcement is reported. To synthesize it, carbon fibers （CFs） have been first grafted by graphene oxide （GO）, and then carbon nanotubes （CNTs） have been in-situ grown on GO-grafted CFs by catalytic chemical vapor deposition. Characterizations on this novel reinforcement show that GO grafting cannot only nondestructively improve the surface chemical activity of CFs but also protect CFs against the high-temperature corrosion of metal catalyst during CNT growth, which maintains their tensile properties. Tensile property tests for unidirectional C/Cs with different preforms show that this novel reinforcement can endow C/C with improved tensile properties, 32% and 87% higher than that of pure C/C and C/C only doped with in-situ grown CNTs. This work would open up a possibility to fabricate multiscale C/Cs with excellent global performance.

关键词： Multiscale reinforcement Carbon fiber Graphene oxide Carbon nanotube Carbon/carbon composite Tensile property

Effect of matrix sub-layer interfacial fracture on residual strength improvement of the fatigued carbon/carbon composites

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2018年第7期34卷 1243-1249页

作者： Jing Cheng he-jun li Shou-yang Zhang li-zhen Xue state Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi'an 710072 China

In the present study, flexural behavior of carbon fber reinforced pyrolytic carbon matrix composites （C/C composites） before and after fatigue tests had been studied. The results showed that the residual flexural strengths of the samples had been improved after fatigue tests, and the fracture mechanisms of the original and post-fatigue specimens had some differences. Fracture mechanism of the original specimens could be described as fiber/matrix interfacial de-bonding, and the dominant damage of the post-fatigue specimens could be regarded as pyrolytic carbon sub-layers＇ step-delamination. The degradation of matrix sub-layer interfacial bonding strength was beneficial to improve the mechanical properties of C/C composites.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.

关键词： Carbon/carbon composites Fatigue behavior Interface Strengthening mechanism

周恩来奋斗观的生成逻辑、内涵意蕴及对青年的启示

在线全文

学校读者我要写书评

暂无评论

齐齐哈尔大学学报（哲学社会科学版） 2024年第3期 82-86页

作者：贺立军毕德印河北工业大学马克思主义学院天津300401

周恩来是奋斗者的杰出楷模,他的一生是中国共产党人为中国人民谋幸福、为中华民族伟大复兴而艰苦奋斗的真实写照。周恩来自青少年时期开始,多次在书信、演讲及题词中提出诸多有关奋斗的思想观点,意蕴丰富且系统。站在向第二个百年奋斗... 详细信息

周恩来是奋斗者的杰出楷模,他的一生是中国共产党人为中国人民谋幸福、为中华民族伟大复兴而艰苦奋斗的真实写照。周恩来自青少年时期开始,多次在书信、演讲及题词中提出诸多有关奋斗的思想观点,意蕴丰富且系统。站在向第二个百年奋斗目标奋进的历史起点上,科学探析周恩来奋斗观的生成逻辑,系统阐释其内涵意蕴,对于筑牢青年理想信念之基、锤炼青年过硬担当本领、培养青年艰苦奋斗精神、激励青年投身奋斗实践具有重要的启示价值。

关键词：周恩来奋斗观青年

牙髓牙周病变患者感染根管的主要致病菌及其影响因素分析

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

中国现代医学杂志 2024年第6期34卷 60-65页

作者：宋洋唐璐易玉龙何莉君薛莉成都大学附属医院口腔科四川成都610081

目的探讨牙髓牙周病变患者感染根管的主要致病菌及其影响因素分析。方法选取2020年2月—2021年8月成都大学附属医院收治的88例牙周牙髓病变患者,根据是否根管感染分组为感染组(38例)和未感染组(50例)。分析感染患者病原菌的分布构成,采... 详细信息

目的探讨牙髓牙周病变患者感染根管的主要致病菌及其影响因素分析。方法选取2020年2月—2021年8月成都大学附属医院收治的88例牙周牙髓病变患者,根据是否根管感染分组为感染组(38例)和未感染组(50例)。分析感染患者病原菌的分布构成,采用单因素和多因素一般Logistic回归分析影响感染的危险因素。比较两组患者血清和龈沟液白细胞介素-1β(IL-1β)、干扰素-γ(IFN-γ)水平,并采用受试者工作特征曲线分析IL-1β、IFN-γ水平对根管感染的诊断效能。结果88例患者中感染38例(43.18%),共检出46株病原菌,其中革兰阳性菌28株(60.87%),包括葡萄球菌属(21.74%)、微单胞菌(17.39%)、粪肠球菌(13.04%)、放线菌(4.35%)及其他革兰阳性菌(4.35%);革兰阴性菌18株(39.13%),包括中间普氏菌(15.22%)、福塞类杆菌(10.87%)、牙龈卟啉单胞菌(4.35%)、产黑普雷沃菌(4.35%)及其他革兰阴性菌(4.35%)。两组患者性别构成、年龄、体重指数、收缩压、舒张压比较,差异均无统计学意义(P>0.05)。感染组刷牙时间<3 min、刷牙次数1次、喜食甜食、龋牙占比高于未感染组,血清和龈沟液中IL-1β和IFN-γ水平高于未感染组(P<0.05)。多因素一般Logistic回归分析结果显示:刷牙时间<3 min[O^R=1.950(95%CI:1.116,3.410)]、刷牙次数1次[O^R=2.192(95%CI:1.100,4.371)]、喜食甜食[O^R=1.754(95%CI:1.081,2.847)]、龋牙[O^R=2.252(95%CI:1.166,4.352)]、血清IL-1β≥7.69 ng/mL[O^R=1.842(95%CI:1.195,2.841)]、龈沟液IL-1β≥22.59 ng/mL[O^R=1.519(95%CI:1.032,2.235)]、血清IFN-γ≥11.73 ng/mL[O^R=1.701(95%CI:1.147,2.522)]、龈沟液IFN-γ≥8.33 ng/mL[O^R=1.495(95%CI:1.032,2.165)]均是根管感染的危险因素(P<0.05)。龈沟液IL-β为22.59 ng/mL时曲线下面积最高,为0.850(95%CI:0.763,0.937),血清IL-β为7.69 ng/mL时敏感性最高,为86.8%(95%CI:0.826,0.908),龈沟液IL-β为22.59 ng/mL时特异性最高,为92.0%(95%CI:0.895,0.937)。结论牙髓牙周病变患者根管感染病原菌主要为革兰阳性菌,刷牙时间、刷牙次数、喜食甜食、龋牙、血清IL-1β≥7.69 ng/mL、龈沟液IL-1β≥22.59 ng/mL、血清IFN-γ≥11.73 ng/mL、龈沟液IFN-γ≥8.33 ng/mL均是根管感染的影响因素,其中感染患者的血清和龈沟液IL-1β、IFN-γ均处于高表达状态,对于根管感染具有良好的诊断效能。

关键词：牙髓牙周病变根管感染 IL-1β IFN-γ 诊断价值

In Vitro Biocompatibility of MC3T3-E1 Osteoblast-like Cells on Arg-Gly-Asp Acid Peptides Immobilized Graphite-like Carbon Coating on Carbon/Carbon Composites

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2017年第6期30卷 558-566页

作者： Sheng Cao he-jun li Ke-Zhi li Jin-Hua Lu Lei-Lei Zhang State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China

Carbon/carbon （C/C） composites were deposited with graphite-like carbon （GLC） coating, and then, Arg-Gly- Asp acid （RGD） peptides were successfully immobilized onto the functionalized GLC coating. GLC coating was utilized to prevent carbon particles releasing and create a uniform surface condition for C/C composites. RGD peptides were utilized to improve biocompatibility of GLC coating. Surface chemical characterizations of functionalized GLC coating were detected by contact angle measurement, X-ray photoelectron spectroscopy and Raman spectra. Optical morphology of GLC coatings was observed by confocal laser scanning microscopy. In vitro biological performance was determined using samples seeded with MC3T3-E1 osteoblast-like cells and cultured for 1 week. Surface characterizations and morphological analysis indicated that C/C composites were covered by a dense and uniform GLC coating. Contact angle of GLC coating was reduced to 27.2° when it was functionalized by H202 oxidation at 40 ℃ for 1 h. In vitro cytological test showed that the RGD peptides immobilized GLC coating had a significant improvement in biocompatibility. It was suggested that RGD peptides provided GLC coating with a bioactive surface to improve cell adhesion and proliferation on C/C composites.

关键词： MC3T3-E1 osteoblast-like cells Carbon/carbon composites Graphite-like carbon (GLC) coating Arg-Gly-Asp acid (RGD) peptides Surface modification

Numerical simulation on thermal expansion coefficient of 3D braided C/C composites

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2014年第1期33卷 99-106页

作者： Chun-Xia Hu he-jun li Shou-Yang Zhang Yong-Shan Song State Key Laboratory of Solidification Processing Carbon/Carbon Composites Research Center Northwestern Polytechnical University School of Mechatronic Engineering Northwestern Polytechnical University

To effectively get the thermal expansion coef- ficient （CTE） of three-dimensional （3D） braided C/C composites and study the variations, a VC＋＋ program with graphical user interfaces was obtained, based on the yam unit model and numerical analysis. With the limited basic properties of carbon fibers and carbon matrix, CTE of 3D braided C/C composites is obtained at 85 ~C. The deviation between the simulated and exl^erimental axial CTE of 3D braided C/C composites is no more than 11%. The effects of different parameters （including the braiding angle of 3D braided preform, the fiber volume fraction and the porosity of 3D braided C/C composites, and the elastic modulus, Poisson＇s ratio and CTEs of carbon fibers and carbon matrix） were analyzed with the program. The results show that the axial CTE of C/C composites decreases with the increase of the braiding angle, the fiber volume fraction, and the porosity of 3D braided C/C composites. The transverse elastic modulus of carbon fibers has the greatest effect on the axial CTE among the studied mechanical parameters, followed by the elastic modulus and Poisson＇s ratio of carbon matrix.

关键词： 3D braided C/C composites Rosen-Hashin equation Axial CTE Simulation

在线全文

学校读者我要写书评

暂无评论

锑化铟晶体空位缺陷的正电子湮灭研究

激光与红外 2024年第1期54卷 72-77页

作者：赵超董涛折伟林彭志强贺利军张孟川中国电子科技集团公司第十一研究所北京100015

锑化铟晶体材料的电学性能是影响最终制备的红外探测器件性能的关键因素。材料内部的杂质以及点缺陷特别是空位缺陷会极大的影响材料的电学性能,有时甚至会导致材料反型。本文利用正电子湮灭谱对锑化铟晶体材料的空位缺陷类型进行了研究... 详细信息

锑化铟晶体材料的电学性能是影响最终制备的红外探测器件性能的关键因素。材料内部的杂质以及点缺陷特别是空位缺陷会极大的影响材料的电学性能,有时甚至会导致材料反型。本文利用正电子湮灭谱对锑化铟晶体材料的空位缺陷类型进行了研究,同时还对不同晶体生长拉速、导电类型晶体材料的正电子湮灭寿命进行分析。结果表明其内部主要为V In型空位缺陷,且在一定拉速范围内,正电子湮灭寿命基本无变化,此外空位缺陷也不是导致N型锑化铟晶体材料导电类型反型的主要原因。

关键词：锑化铟红外探测器正电子湮灭谱空位缺陷晶体生长拉速导电类型

Impact of benazepril on contrast-induced acute kidney injury for patients with mild to moderate renal insufficiency undergoing percutaneous coronary intervention

在线全文

学校读者我要写书评

暂无评论

Chinese Medical Journal 2011年第14期124卷 2101-2106页

作者： li Xi-ming CONG Hong-liang li Ting-ting he li-jun ZHOU Yu-jie Department of Cardiology Beijing Anzhen Hospital Capital Medical University Beijing 100029 China Department of Cardiology Tianjin Chest Hospital Tianjin Medical University Tianjin 300051 China

Background The role of angiotensin-converting enzyme inhibitors （ACEI） in contrast-induced acute kidney injury （CI-AKI） is controversial. Some studies pointed out that it was effective in the prevention of CI-AKI, while some concluded that it was one risk for CI-AKI, especially for patients with pre-existing renal impairment. The purpose of this study was to assess the influence of benazepril administration on the development of CI-AKI in patients with mild to moderate renal insufficiency undergoing coronary *** One hundred and fourteen patients with mild to moderate impairment of renal function were enrolled before coronary angioplasty, who were randomly assigned to benazepril group （n=52） and control group （n=62）. In the benazepril group, the patients received benazepril tablets 10 mg per day at least for 3 days before procedure. CI-AKI was defined as an increase of≥25％ in creatinine over the baseline value or increase of 0.5 mg/L within 72 hours of *** Patients were well matched with no significant differences at baseline in all measured parameters between two groups. The incidence of CI-AKI was lower by 64％ in the benazepril group compared with control group but without statistical significance （3.45％ vs. 9.68％, P=0.506）. Compared with benazepril group, estimated glomerular filtration rate （eGFR） level significantly decreased from （70.64＋16.38） ml·min-1·1.73 m-2 to （67.30＋11.99） ml·min-1·1.73 m-2 in control group （P=0.038）. There was no significant difference for the post-procedure decreased eGFR from baseline （△eGFR）between two groups （benazepril group （0.67＋12.67） ml·min-1·1.73 m-2 vs. control group （-3.33±12.39） ml·min-1·1.73 m-2,P=0.092）. In diabetic subgroup analysis, △eGFR in benazepril group was slightly lower than that in the control group, but the difference was not statistically *** Benazepril has a protective effect on mild to moderate impairment of renal function during coronary angioplasty. It is

关键词： angiotensin-converting enzyme inhibitors contrast-induced acute kidney injury percutaneous coronary intervention

In situ anchoring in carbon matrix of Bi_(2)O_(2)CO_(3) as a high-performance anode material for li-ion batteries

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第8期43卷 3634-3646页

作者： Pu-Qiang he jun Guo Hui Huang Zhong-Cheng Guo Faculty of Metallurgy and Energy Engineering Kunming University of Science and TechnologyKunming 650093China Research Center of Metallurgical Electrode Materials Engineering Technology Kunming 650106China Kunming hendera Science and Technology Co. Ltd.Kunming 650106China

Bismuth-based anode materials have been regarded as promising li-ion batteries due to their high theoretical ***,their low conductivity and associated volume expansion inhabited their *** this work,Bi_(2)O_(2)CO_(3)@C composites were successfully synthesized by in situ anchoring of flower-like Bi_(2)O_(2)CO_(3) nanosheets on a carbon-based substrate via *** unique composited structure of Bi_2O_(2)-CO_(3)@C leads to a stable specific capacity of 547 mAh·g^(-1)after 100 cycles at a current density of 0.1 A·g^(-1).Notably,it demonstrates excellent rate capability with a specific capacity of 210 mAh·g^(-1)at 5 A·g^(-1).After 550 cycles at a current density of 0.5 A·g^(-1),a high reversible capacity of nearly 400 mAh·g^(-1)was ***,in situ X-ray diffraction measurements clearly demonstrate the conversion between Bi and li_(3)Bi during alloying/dealloying,confirming the good electrochemical reversibility of the materials for li *** reaction kinetics of Bi_(2)O_(2)CO_(3)@C were further investigated using galvanostatic intermittent titration ***,Bi_2O_(2)-CO_(3)@C exhibited excellent long-term stability,maintaining its high reversible capacity for over 200 cycles at a current density of 0.5 A·g^(-1)in a full cell configuration using li_(1.20)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2) as the cathode *** result further underscores its promising potential for lithium-ion *** work may provide inspiration for the design of alloy-type negative electrode materials for high-performance rechargeable batteries.

关键词： Bi_(2)O_(2)CO_(3) Composite materials Anode materials Full batteries