检索结果-内蒙古大学图书馆

Microstructure and mechanical properties of c/Sic-niobium alloy (c103) joint brazed with TicuAg alloy for aerospace applications

引用

cERAMIcS INTERNATIONAL 2023年第17期49卷 29265-29273页

作者： Kamal, Anurag Shukla, Anoop Kumar Shinde, Vijay M. Rajasekhar, Buragadda, V Indian Inst Technol BHU Dept Chem Engn Varanasi 221005 India Indian Space Res Org ISRO Ceram Matrix Prod Div ASCG PCM Vikram Sarabhai Space Ctr Thiruvananthapuram 695022 India ISRO Vikram Sarabhai Space Ctr Special Met Facil MMG MME Thiruvananthapuram 695022 India

In this study, niobium-based alloy c103 is joined to carbon fibre-reinforced Sic (c/Sic) composite utilising commercially available Ticusil & REG;and cusil & REG;alloy braze filler material. Various characterisation techniques are employed to investigate the interfacial microstructures and evolution mechanism of c/Sic-c103 junctions. Lap shear strength (LSS) is used to evaluate the mechanical performance of the brazed joints. The results show that adding Ti promotes the growth of "nails", a phenomenon favourable for robust joint quality. However, high Ti content deteriorates the bond strength due to the formation of significant brittle intermetallic phases, causing premature delamination of the joints. The response surface methodology (RSM) is employed to examine the interactions among various operating parameters. To attain the high LSS value, the high temperature, intermediate reaction time, and low cooling rate are necessary for a Ticusil-based joint, whereas high temperature, low reaction time, and increased cooling rate are preferred for a cusil-based joint.

关键词： A Joining B composites c Mechanical properties E Engine components Structural applications D Sic

来源：评论

学校读者我要写书评

暂无评论

A mechanism underlying stimulation and inhibition of protein kinase c by lyso-Pc: A role of membrane physical state

引用

Science china(Life Sciences) 1998年第6期41卷 584-591页

作者：潘最陈建文 1. State Key Laboratory of Biomacromolecules Institute of Biophysics Chinese Academy of Sciences 100101 Beijing China

Lysophosphatidylcholine (lyso Pc) biphasically regulates the diacylglycerol induced activation of protein kinase c (PKc). In common parlance, lyso Pc stimulates PKc at low concentrations, but, conversely, inhibits it at high concentrations. The activity of purified PKc from rat brains was measured in the vesicles made up of dipalmitoylphosphatidylserine (DPPS), 1,2 sn diolein (DOG) and different molar ratios of 1 palmitoyl sn glycerol 3 phosphoryl choline (c16:0 lyso Pc). The effect, i.e. stimulation or inhibition on PKc by c16:0 lyso Pc, depends on DPPS and DOG concentrations as well as its own concentration. When the concentration of DOG is stable, this c16:0 lyso Pc action depends on c16:0 lyso Pc/DPPS molar ratio. Differential scanning calorimetry (DSc), two fluorescence probes and light scattering were used to analyze the physical characteristics of membrane, including thermotropic phase behavior, the turbidity, the lipid molecular acyl chains packing and the head group spacing. The more adulteration of c16:0 lyso Pc in liposome bilayer membrane, the looser acyl chains pack, and the broader head group spacing. DSc results show that there are two immiscible lipid areas in the membrane: c16:0 lyso Pc rich area and c16:0 lyso Pc poor area. When c16:0 lyso Pc/DPPS molar ratio was 0 234, the two areas had the broadest boundary and the activation of PKc was the highest. When the ratio was over 0 434, the phase transition of DPPS disappeared; micelle tended to substitute the structure of bilayer; the activity of PKc was inhibited completely. DOG can stabilize the bilayer structure of membrane, so the c16:0 lyso Pc/DPPS molar ratios to inhibit PKc in lipid mixture with DOG are higher than that without DOG. The ability of c16:0 lyso Pc to change the physical properties and the structure of membrane plays an important role in its effect on PKc activation.

关键词： protein kinases c lysophosphatidylcholine diolein differential scanning calorimetry physical properties of membrane.

来源：评论

学校读者我要写书评

暂无评论

Tribological behavior and wear mechanism of c/c-Sic brake discs based on third-body layer

引用

INTERNATIONAL JOURNAL OF APPLIED cERAMIc TEcHNOLOGY 2023年第2期20卷 1310-1326页

作者： Hui, Yang Liu, Guimin Shi, Ruidong Zhang, Yong Yan, Tao Acad Army Armored Forces Dept Equipment Maintenance & Remfg Engn Beijing 100072 Peoples R China

c/c-Sic composites are promising candidates for heavy-duty tracked vehicle brake discs. A third-body layer (TBL) can be formed on the surface of c/c-Sic self-mated brake discs, which has an important impact on tribological behavior and wear mechanism of brake discs. Herein, the formation conditions and evolution process of TBL and its effect on friction and wear properties were investigated. An appropriate braking pressure and speed (P and V) are beneficial to the cutting of asperities and refinement of wear debris on the contact surface, which are preconditions for the formation of original TBL. The original TBL can be formed under the P center dot V of 12, 15, and 16, which effectively improve braking stability and reduce the wear rate. During the continuous braking process, the original TBL undergoes growth, stabilization, destruction, and regeneration. Under the frictional heat and compressive stress, wear debris gradually evolves into a uniform and dense TBL. The average coefficient of friction and wear rate reach to the lowest value of .446 and 38.5 x 10(-3) cm(3)/MJ, respectively. A continuous high temperature in the later stages of braking leads to severe oxidative wear. The newly formed TBL covers the original surface to form a multilayered structure, indicating the TBL undergoes destruction and regeneration.

关键词： c c-Sic friction third-body layer tribological behavior wear mechanism

来源：评论

学校读者我要写书评

暂无评论

comprehensive determination of seven polyphenols in Eucommia ulmoides and its anti-oxidative stress activity in c. elegans

引用

JOURNAL OF FOOD MEASUREMENT AND cHARAcTERIZATION 2019年第4期13卷 2903-2909页

作者： Hou, Peilin Wang, Qing Qi, Wuqin Zhang, Yanqing Xie, Junbo Tianjin Univ Commerce Coll Biotechnol & Food Sci Tianjin 300134 Peoples R China Tianjin Univ Tradit Chinese Med Sch Chinese Mat Med Tianjin 301617 Peoples R China

In this study, an efficient HPLc method was developed and validated to determine seven polyphenols, i.e. chlorogenic acid, caffeic acid, protocatechuic acid, geniposide, rutin, quercetin and isorhamnetin, in different parts (leaves, barks and fruits) of Eucommia ulmoides. A Luna c-18 column (150 mm x 3.9 mm, 5.0 mu m) was applied and eluted with a gradient of acetonitrile-modified aqueous mobile phase (containing 1% acetic acid). 260 nm, 326 nm, and 360 nm were used as the detection wavelengths. With the developed method, these seven polyphenols were successfully assayed and their contents in different parts of E. ulmoides were compared. The results showed that these polyphenols displayed different distribution in the leaves, barks and fruits. chlorogenic acid, caffeic acid and rutin were their main common constituents. ABTS and DPPH free radical scavenging assay indicated that E. ulmoides displayed significant antioxidant activities in vitro. In addition, the extracts of the three parts can significantly increase the anti-oxidative stress level in wild-type c. elegans and prolong its lifespan, further demonstrating the antioxidant activity of Eucommia ulmoides.

关键词： Eucommia ulmoides chlorogenic acid caffeic acid Rutin Anti-oxidation c elegans

来源：评论

学校读者我要写书评

暂无评论

Effect of a Ti plus c Granule Size on combustion in a Nitrogen Flow

引用

cOMBUSTION EXPLOSION AND SHOcK WAVES 2021年第1期57卷 60-66页

作者： Seplyarskii, B. S. Kochetkov, R. A. Lisina, T. G. Abzalov, N. I. Russian Acad Sci Merzhanov Inst Struct Macrokinet & Mat Sci Chernogolovka 142432 Russia

Dependence of the combustion of a Ti + c granular charge on a granule size is experimentally studied. It is revealed that the burning rate of a granular mixture of all fractions used in the work is higher than the burning rate of a bulk-density powder mixture. It is shown that, with a decrease in the granule size, the burning rate of the charge in the absence of gas decreases due to an increase in the number of boundaries between the granules per unit length of the sample. A strong influence of the nitrogen flow on the burning rate of both coarse and fine granules is established. It is shown that, in contrast to fine granules, an increase in the nitrogen flow rate of coarse granules up to 600 liters/h leads to a transition to convective combustion. The studies performed indicate that, despite the structural analogy between mechanically activated and granular mixtures, the relationship between the combustion time and the front transition time in granular mixtures is completely different. This means that the combustion of granular mixtures even in the absence of a gas flow cannot be explained within the framework of a microheterogeneous model.

关键词： SHS Ti + c granule size cocurrent gas flow convective combustion microheterogeneous model

来源：评论

学校读者我要写书评

暂无评论

Laser flash photolysis of fullerols of c_(60) and of c_(70) in aqueous solutions

引用

Science china chemistry 1998年第3期41卷 259-265页

作者：陆长元姚思德王文锋童永彭林维真荣廷文林念芸 1. Laboratory of Radiation Chemistry Shanghai Institute of Nuclear Research Chinese Academy of Sciences 201800 Shanghai China 2. Nuclear Analysis Center Shanghai Institute of Nuclear Research Chinese Academy of Sciences 201800 Shanghai China

Fullerols of c 60 and of c 70 \ [c 60 (OH)\-\%n\%, c 70 (OH)\-\%m\%], water\|soluble fullerene derivatives, unlike some other fullerene derivatives (such as c 60 (c\-4H\-6O), c 60 (c\-3H\-7N) and c 60 [c(cOOEt)\-2]\-\%x\%), do not result in excited triplet state but in ionization via monophotonic process in aqueous solutions with 248 nm laser. The quantum yields of formation of hydrated electron ( Φ e - ) are determined to be 0.08 and 0.11 for fullerols of c 60 and of c 70 respectively at room temperature (ca. 15℃) with KI solution used as reference. By laser flash photolysis and oxidation of sulfate radical anion SO -· \-4, the fullerol radical cation or neutral radical of c 60 is confirmed to be existent and the transient absorption spectra of fullerol radical cation of c 70 are observed for the first time.

关键词： fullerol of c 60 fullerol of c 70 laser flash photolysis monophotonic ionization radical.

来源：评论

学校读者我要写书评

暂无评论

combustion synthesis of c/MgAl2O4 composite powders using magnesium oxalate as carbon source

引用

INTERNATIONAL JOURNAL OF APPLIED cERAMIc TEcHNOLOGY 2019年第3期16卷 1253-1263页

作者： Lv, Lihua Xiao, Guoqing Ding, Donghai Ren, Yun Yang, Shoulei Yang, Pan Hou, Xing Xian Univ Architecture & Technol Coll Mat & Mineral Resources Xian Shaanxi Peoples R China

In order to solve the bottleneck problems including uniform distribution, and oxidation resistance of nano carbons in oxide ceramics, c/MgAl2O4 composite powders were prepared with Mgc2O4 center dot 2H(2)O, MgO2, Al2O3, and Al as raw materials via combustion method under argon atmosphere. The maximum adding amount of Mgc2O4 center dot 2H(2)O is 34.34 wt%. The phase compositions and microstructures of combustion products were characterized through X-ray diffraction (XRD), scanning electron microscope (SEM)/EDX, and Raman spectroscopy. The results showed that the phases of products are mainly composed of MgAl2O4 and carbon. The prepared MgAl2O4 has granular and rod-like morphologies, and the free carbon (1.172 wt%) exists between particles of MgAl2O4. Moreover, the addition of Fec2O4 as catalyst in raw materials ratio would be beneficial for improving crystallization of in situ carbon generated in the products. The oxidation activation energy of the prepared c/MgAl2O4 composite powders was calculated as 143.01 kJ/mol which was 22.17% higher than that of carbon black/MgAl2O4 powders (117.06 kJ/mol), suggesting that the c/MgAl2O4 composite powders prepared by combustion synthesis have excellent oxidation resistance.

关键词： c MgAl2O4 composite powders combustion synthesis microstructure

来源：评论

学校读者我要写书评

暂无评论

Simultaneous enhancement of mechanical and ablation properties of c/c composites modified by (Hf-Ta-Zr)c solid solution ceramics

引用

JOURNAL OF THE EUROPEAN cERAMIc SOcIETY 2023年第8期43卷 3182-3190页

作者： Miao, Qing Fu, Yanqin chen, Hui Zhang, Jianhua Zhao, Junhao Zhang, Yulei Northwestern Polytech Univ Carbon Carbon Composites Res Ctr State Key Lab Solidificat Proc Xian 710072 Peoples R China Henan Acad Sci Carbon Matrix Composites Res Inst Henan Key Lab High Performance Carbon Fiber Reinfo Zhengzhou 450046 Peoples R China

In order to improve the mechanical and ablative resistance of c/c composites, (Hf-Ta-Zr)c single-phase solid solution ceramics were introduced into c/c composites by polymer infiltration and pyrolysis (PIP) to fabricate (Hf-Ta-Zr)c modified c/c composites (HTZ). Their mechanical property and ablation resistance were studied. The results showed that HTZ achieved simultaneous enhancement of mechanical property and ablative resis-tance. Their flexural strength and modulus could reach 219.34 MPa and 24.82 GPa, respectively. In addition, the mass and linear ablation rate of HTZ were 0.379 mg/s and 0.667 mu m/s, respectively after the 90 s oxyacetylene ablation. A dense Hf-Ta-Zr-O multiphase oxide layer was formed on the surface of the HTZ during ablation process, which protected the interior modified c/c composites from ablation. Our work expands a rational design of modified c/c composites and broaden the application of solid solution ceramic in the field of ultra-high temperature ablation resistance for carbon or ceramic-based composites.

关键词： (Hf-Ta-Zr)c solid solution ceramics Polymer infiltration and pyrolysis c c composites Mechanical property Ablation resistance

来源：评论

学校读者我要写书评

暂无评论

Expression of structural proteins of hepatitis c virus (HcV) in mammalian cells

引用

Science china(Life Sciences) 1998年第1期41卷 47-55页

作者：李迎春李光地孔玉英汪垣王宇闻玉梅 1. Shanghai Institute of Biochemistry Chinese Academy of Sciences 200031 Shanghai China 2. Institute of Liver Disease Beijing Medical University 100044 Beijing China 3. Laboratory of Medical Molecular Virology Ministry of Public Health Shanghai Medical University 200031 Shanghai China

The vaccinia viral vector containing T7 promoter was used to construct the expression plasmids carrying HcV structural genes of c, E1 and E2/NS1. These genes were transiently expressed in mammalian cells in the presence of the T7 RNA polymerase which was provided by the recombinant vaccinia virus vTT7. Expression of mature core protein, envelope protein E1 and E2 was detected by Western blot using HcV patient sera as the primary antibodies. It was found that the sera from different HcV patients reacted differently with the expressed products, so did the sera collected at different times from the same patient, from whom the HcV structural genes were isolated. Among six mammalian cell lines, Vero and HeLa were the most suitable for the expression of c, E1 and E2. The recombinant vaccinia viruses have been constructed to constantly produce the c, E1 and E2 proteins for further research.

关键词： hepatitis c virus core protein envelope protein recombinant vaccinia virus transient expression immunoblotting.

来源：评论

学校读者我要写书评

暂无评论

Effect of h-BN addition on thermo-physical properties and phonon mechanisms of c/c-BN composites

引用

cARBON 2023年 204卷 346-356页

作者： Niu, Zi-bo Xiao, Peng Zhang, Bengu Li, Zhuan chen, Fu chen, Pengju Li, Yang Cent South Univ Natl Key Lab Sci & Technol High Strength Struct Ma Changsha 410083 Peoples R China Cent South Univ Powder Met Res Inst Changsha 410083 Peoples R China

c/c-BN composites containing different contents of h-BN particles were prepared by chemical vapor infiltration (cVI), presenting different microstructures and pyrolytic carbon (Pyc) textures. The effects of different micro-structures and Pyc textures on the thermo-physical properties and their phonon mechanisms at 30-900 degrees c were investigated. The temperature dependence of heat capacity follows Debye's phonon theory, especially in the low -temperature section (30-300 degrees c) and the temperature dependence of thermal conductivity is determined by heat capacity and mean free length of phonon. Due to the higher texture of h-BN and regenerative laminar Pyc (ReL-Pyc), h-BN addition causes higher Debye temperature (Theta D) and high sensitivity of thermal conductivity to temperature. Besides, h-BN addition significantly changes the microstructure of composites such as pore struc-ture, Pyc morphology, crack distribution and fiber/Pyc interface bonding state, causing the transformation of thermal conductivity from anisotropy to isotropy. Finally, based on the different microstructures of composites, the microstructure model and thermal resistance formulas of composites were established and coincident with the experimental results.

关键词： c c composite Heat capacity Thermal conductivity Phonon mechanisms

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：