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Ablation behaviors of Sic nanowire-reinforced Zrc-Sic coating-matrix integrated c/c composites with different ratios of precursors

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JOURNAL OF THE EUROPEAN cERAMIc SOcIETY 2022年第15期42卷 6774-6784页

作者： Tian, Xinfa Yang, Li Li, Bo Li, Hejun Shi, Xiaohong Lin, Hongjiao Northwestern Polytech Univ Shaanxi Prov Key Lab Fiber Reinforced Light Compos Xian 710072 Shaanxi Peoples R China Northwestern Polytech Univ Sch Mech Civil Engn & Architecture Xian Peoples R China

A novel method to prepare a coating on the c/c composite is discussed. The precursor infiltration pyrolysis method is usually applied to prepare interior ceramic matrix, thus Sic nanowires that can absorb the surficial precursor are added to prepare surficial ceramics. The method accomplishes the integration of the coating and the matrix so that no coating peels off after ablation. Moreover, the material with a Zrc/Sic precursor ratio of 5:1 (Z5S1), whose mass and linear rates are 0.47 mg/s and 0.95 mu m/s, exhibits the highest overall resistance to ablation. The results demonstrate that higher Zrc content and more uniform phase distribution are beneficial to keep ZrO2 in solid and form a denser and firmer oxide layer, which is more effective in improving the ablation resistance of the c/c composite.

关键词： c Ablation Precursor infiltration pyrolysis coating-matrix integration

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Optimized ablation resistance behavior and mechanism of c/Sic composites with high thermal conductive channels

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JOURNAL OF THE AMERIcAN cERAMIc SOcIETY 2023年第11期106卷 6937-6950页

作者： cao, Yejie Zhang, Yunhai Liu, Yongsheng cao, Liyang Shao, Xiongjian Wang, Jing Northwestern Polytech Univ Sci & Technol Thermostructural Composites Mat Lab Xian Shaanxi Peoples R China Natl Univ Def Technol Sci & Technol Adv Ceram Fibers & Composites Lab Changsha Hunan Peoples R China China Acad Launch Vehicle Technol Beijing Inst Astronaut Syst Engn Beijing Peoples R China

Aimed to enhance the high-temperature service performance of c/Sic composites in high-speed aircraft thermal protection system, in this article, pitch-based carbon fibers were used to construct high thermal conductive channels to improve the heat transfer capability of c/Sic composites. The results revealed that the as-prepared composites equipped with 4.7 times higher thermal conductivity than that of conventional c/Sic composites. The oxyacetylene flame ablation test confirmed that the constructed high thermal conductive channels, which quickly conducted the heat flow from the ablation center area to other areas is the main reason of as-prepared composites exhibiting a very impressive ablation resistance property. Briefly, the ablation temperature of the as-prepared composite surfaces considerably dropped by about 300 & DEG;c compared with conventional c/Sic composites, while the linear ablation rate and mass ablation rate of the composites are 1.27 & mu;m/s and 0.61 mg/s respectively, which is superior to many recent reports, demonstrating that this article provides a simple but highly effective measure to improve the ablation resistance property of c/Sic composites.

关键词： ablation resistance c Sic composites high thermal conductive channels thermal conductivity

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An Ultrathin Microwave Metamaterial Absorber for c, X, and Ku Band Applications

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JOURNAL OF ELEcTRONIc MATERIALS 2021年第12期50卷 7275-7282页

作者： Elakkiya, A. Radha, S. Sreeja, B. S. Manikandan, E. Sri Sivasubramaniya Nadar Coll Engn Dept ECE Chennai 603110 Tamil Nadu India VIT Univ Sch SENSE Dept ECE Chennai Campus Chennai 600127 Tamil Nadu India

A five-band polarization-insensitive microwave metamaterial absorber (MMA) is discussed in this paper. The unit cell of the proposed MMA is composed of the top patch and a ground metallic plane, both separated by an FR4 dielectric substrate having an ultrathin thickness of 0.014 lambda. The proposed absorber structure offers five different absorption peaks at 5.4 GHz (c band), 8.7 GHz (X band), 14.53 GHz, 15.25 GHz, and 15.68 GHz (Ku band) with the absorptivity of 98%, 86%, 99%, 99.8%, and 99.9%, respectively, for both transverse electric (TE) and transverse magnetic (TM) modes. The analysis of the electric field, magnetic field, polarization, and angle independency has been performed to understand the absorption mechanism easily. The sensing behavior of the structure is analyzed by adding the analyte over the top metal layer. The microwave MMA has been fabricated and measured. The fabrication results agree with the simulation results. The design of the proposed absorber is expected to find application in explosive detection, sensing, defense, and airborne radar applications.

关键词： Microwave metamaterial absorber c X and Ku band sensing fabrication

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Ablation behavior of c/c-Zr1-xHfxc-Sic composites under an oxyacetylene flame at above 2500 °c

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JOURNAL OF MATERIALS RESEARcH AND TEcHNOLOGY-JMR&T 2023年 24卷 3235-3251页

作者： Jiao, Xiaoyang He, Qinchuan Qing, Mingcong Wang, Yiqun Yin, Xuemin Chengdu Univ Technol Coll Mat & Chem & Chem Engn Chengdu 610059 Peoples R China Northwestern Polytech Univ Sch Mat Sci & Engn Xian 710072 Peoples R China

In order to enhance ablation resistance of c/c composites, Zr1-xHfxc and Sic were intro-duced into c/c composites, and ablation behavior of the composites was studied. In the composites (cHZS), Hfc and Zrc produced a solid solution, and solid solubility of Hfc in Zrc was 0.4, which indicated that the solid solution was defined to be Zr0.6Hf0.4c. compared with c/c-Zrc-Sic composites (cZS), cHZS possessed a better ablation resistance. During ablation of cHZS, Zr0.6Hf0.4c is oxidized to produce HfO2 and ZrO2, and HfO2 particles played a pinning effect, which fixed molten oxide coating. Moreover, due to low cTE of HfO2 and decreasing content of ZrO2, there was a smaller thermal stress and its distribu-tion area on cHZS ablation surface, thus thermal stress corrosion was weakened to strengthen integrity of oxide coating. In this case, a complete and continuous HfO2-ZrO2 coating was formed on cHZS surface, which could resist oxygen diffusion and reduce oxidation rate of the composites.& cOPY;2023 The Authors. Published by Elsevier B.V. This is an open access article under the cc BY-Nc-ND license (http://***/licenses/by-nc-nd/4.0/).

关键词： c c composites Zr1-xHfxc solid solution composition Microstructure Ablation behavior

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Histone Deacetylase 3 Inhibitor Suppresses Hepatitis c Virus Replication by Regulating Apo-A1 and LEAP-1 Expression

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Virologica Sinica 2018年第5期33卷 418-428页

作者： Yuan Zhou Qian Wang Qi Yang Jielin Tang chonghui Xu Dongwei Gai Xinwen chen Jizheng chen State Key Laboratory of Virology Wuhan Institute of VirologyChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100101China Jiangsu Province Key Laboratory of Human Functional Genomies Department of Biochemistry and Molecular BiologyNanjing Medical UniversityNanjing 210029China

Histone deacetylase (HDAc) inhibitors show clinical promise for the treatment of cancers, including hepatocellular carcinoma (Hcc). In this study, we investigated the effect of HDAc inhibitor treatment on hepatitis c virus (HcV)replication in Huh7 human liver cells and in a mouse model of HcV infection. Viral replication was markedly suppressed by the HDAc3 inhibitor at concentrations below 1 mmol/L, with no cellular toxicity. This was accompanied by upregulation of liver-expressed antimicrobial peptide 1 (LEAP-1) and downregulation of apolipoprotein-A1 (Apo-A1), as determined by microarray and quantitative RT-PcR analyses. Moreover, HDAc3 was found to modulate the binding of ccAAT-enhancer-binding protein a (c/EBPa), hypoxia-inducible factor 1 a (HIF1 a), and signal transducer and activator of transcription 3 (STAT3) to the LEAP-1 promoter. HDAc3 inhibitor treatment also blocked HcV replication in a mouse model of HcV infection. These results indicate that epigenetic therapy with HDAc3 inhibitor may be a potential treatment for diseases associated with HcV infection such as Hcc.

关键词： Hepatitis c virus (HcV) HDAc3 Apolipoprotein-A1 (Apo-A1) LEAP-1 Hepatocellular carcinoma Viral replication

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A Dual Protection System for Heterostructured 3D cNT/coSe2/c as High Areal capacity Anode for Sodium Storage

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ADVANcED ScIENcE 2020年第5期7卷 1902907页

作者： Yousaf, Muhammad chen, Yijun Tabassum, Hassina Wang, Zhipeng Wang, Yunsong Abid, Adeel Y. Mahmood, Asif Mahmood, Nasir Guo, Shaojun Han, Ray P. S. Gao, Peng Peking Univ Dept Mat Sci & Engn Beijing 100871 Peoples R China Peking Univ Sch Phys Int Ctr Quantum Mat Beijing 100871 Peoples R China Peking Univ Electron Microscopy Lab Beijing 100871 Peoples R China Univ Sydney Sch Chem & Biomol Engn Sydney NSW 2006 Australia RMIT Univ Sch Engn 124 La Trobe St Melbourne Vic 3001 Australia

3D electrode design is normally opted for multiple advantages, however, instability/detachment of active material causes the pulverization and degradation of the structure, and ultimately poor cyclic stability. Here, a dually protected, highly compressible, and freestanding anode is presented for sodium-ion batteries, where 3D carbon nanotube (cNT) sponge is decorated with homogeneously dispersed coSe2 nanoparticles (NPs) which are protected under carbon overcoat (cNT/coSe2/c). The 3D cNT sponge delivers enough space for high mass loading while providing high mechanical strength and faster conduction pathway among the NPs. The outer amorphous carbon overcoat controls the formation of solid electrolyte interphase film by avoiding direct contact of coSe2 with electrolyte, accommodates large volume changes, and ultimately enhances the overall conductivity of cell and assists in transmitting electron to an external circuit. Moreover, the hybrid can be densified up to 11-fold without affecting its microstructure that results in ultrahigh areal mass loading of 17.4 mg cm(-2) and an areal capacity of 7.03 mAh cm(-2) along with a high gravimetric capacity of 531 mAh g(-1) at 100 mA g(-1). Thus, compact and smart devices can be realized by this new electrode design for heavy-duty commercial applications.

关键词： 3D electrodes cNT coSe2 c dual conductive network high areal capacity sodium-ion batteries

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Rh-catalyzed Intramolecular Hydroarylation of Unactivated Alkenes via c-c Bond Activation

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AcS cATALYSIS 2023年第7期13卷 4362-4368页

作者： cheng, Lang Tang, Qi Dai, Ya-Mei Wang, Bi-Qin Hu, Ping cao, Peng Song, Feijie Sichuan Normal Univ Coll Chem & Mat Sci Chengdu 610066 Sichuan Peoples R China

The transition-metal-catalyzed intramolecular hydroarylation of alkenes has been recognized as a straightforward approach for the construction of 3,3-disubstituted 2,3-dihydrobenzofurans. The reactions mainly rely on the reductive Heck reaction of aryl halides or the direct c-H bond activation of arenes bearing a directing group. This work realizes the Rh-catalyzed intramolecular hydroarylation of olefin-tethered benzocyclobutenols via c-c bond activation, which offers an alternative approach to 3,3-disubstituted 2,3-dihydrobenzofurans bearing a 4-beta-keto moiety. The methodology features 100% atom economy and pH-and redox-neutral conditions, and is applicable to the late-stage functionalization of complex molecules. The asymmetric variant has also been achieved with excellent enantioselectivities.

关键词： c c cleavage intramolecular hydroarylation unactivated alkenes asymmetric synthesis postfunctionalization T he transition -metal -catalyzed intramolecular hydroaryla

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Influence of preparation method on microstructure and tribological behavior of c/c-BN composites

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cERAMIcS INTERNATIONAL 2021年第9期47卷 12879-12896页

作者： Liu, Fuhai Yi, Maozhong Ran, Liping Ge, Yicheng Peng, Ke Cent South Univ State Key Lab Powder Met Changsha 410083 Peoples R China

In this study, with 2.5D needle punched carbon felt as reinforcement, hexagonal boron nitride (h-BN) was introduced through chemical vapor infiltration (cVI) and slurry impregnation (SI) methods, and then pyrocarbon was deposited through cVI to convert the BN-containing preform into carbon fiber reinforced carbon-boron nitride binary matrix composites (c/c-BN). The microstructure and mechanical properties of c/c-BN(P) composites prepared by SI combined with cVI were compared with those of c/c-BN(cVI) composites prepared by cVI. The tribological behavior of c/c-BN(P) composites containing different contents of h-BN fillers and c/c-BN (cVI) composites with and without heat treatment was investigated by the ball-on-disk technique in dry sliding conditions using Gcr15 steel balls and Si3N4 balls as sliding counterparts at two different sliding speeds (v = 0.2 and 0.8 m/s), and compared with the c/c composites used as a reference. c/c-BN(P) composites exhibit improved tribological behavior, which can be explained by the combined effect of SI and cVI on the microstructure and mechanical properties, leading to changes in the wear mechanism of the c/c-BN composites. The excellent reinforcement is attributed to the integrity structure of the c/c-BN(P), which can make the selflubricating friction layer stably exist on the surface of the material and significantly reduce the friction coefficient and wear loss of the c/c-BN(P) composite. Furthermore, the mechanical and tribological properties of c/cBN(P) composites can be adjusted by using different volume content of h-BN. The present work shows that c/cBN(P) composites have wide application prospects as anti-friction and wear-resistant materials.

关键词： c c-BN composites Microstructure Tribological behavior Friction Wear

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Preparation of LiFePO4/c via high-temperature ball-milling route and Box-Behnken design-based optimization

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IONIcS 2019年第10期25卷 4597-4606页

作者： Li, Xuetian cui, Yonghui Yu, Lina Shao, Hongmei Shao, Zhongcai Li, chuang Shao, Zhongbao Shenyang Ligong Univ Sch Environm & Chem Engn Shenyang 110159 Liaoning Peoples R China Shenyang Ligong Univ Sch Mat Sci & Engn Shenyang 110159 Liaoning Peoples R China Northeastern Univ Sch Met Shenyang 110819 Liaoning Peoples R China

LiFePO4/c cathode material was prepared via high-temperature ball-milling route with ultrasonic dispersion as mixing process using eutectic molten salt (0.76 LiOH center dot H2O-0.24 Li2cO3) as lithium source. Box-Behnken design was used to study the combined effects of ultrasonic time, ball-milling temperature, and ball-milling time on the discharge capacity to obtain the optimum predicted conditions. The optimum conditions were as follows: ultrasonic time was 63 min, ball-milling temperature was 638 degrees c, and ball-milling time was 7 h. LiFePO4/c prepared from the optimized experimental conditions exhibited a well electrochemical performance;its discharge capacity was 161.3 mAh g(-1) at a 0.1 c-rate which was in consistence with the predicted discharge capacity of 160.2 mAh g(-1). Moreover, its capacity retention rate achieved 93.6% at a 10 c-rate over 100 cycles.

关键词： LiFePO4 c cathode material High-temperature ball-milling route Box-Behnken design

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Stability issues of cO tolerant Pt-based electrocatalysts for polymer electrolyte membrane fuel cells: comparison of Pt/Ti0.8Mo0.2O2-c with PtRu/c

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REAcTION KINETIcS MEcHANISMS AND cATALYSIS 2019年第2期126卷 679-699页

作者： Vass, Adam Borbath, Irina Bakos, Istvan Paszti, Zoltan Safran, Gyorgy Tompos, Andras Hungarian Acad Sci Res Ctr Nat Sci Inst Mat & Environm Chem Magyar Tudosok Korutja 2 H-1117 Budapest Hungary Hungarian Acad Sci Ctr Energy Res Inst Tech Phys & Mat Sci Konkoly Thege M Ut 29-33 H-1121 Budapest Hungary POB 286 H-1519 Budapest Hungary

The stability and cO tolerance of a self-made 20wt% Pt/Ti0.8Mo0.2O2-c mixed oxide-carbon composite supported electrocatalyst was compared to those of a commercial state-of-the-art PtRu/c electrocatalyst by means of cyclic voltammetry and cOads stripping voltammetry measurements. On the Pt/Ti0.8Mo0.2O2-c catalyst the oxidation of cO takes place at exceptionally low potential values (E-cO,E-onset=50mV);the onset potential is shifted to less positive potentials by 150mV compared to the PtRu/c catalyst. A stability test involving 500 polarization cycles revealed that the PtRu/c catalyst suffered more significant degradation than the composite supported Pt catalyst. XPS measurements indicated that the degradation is connected to ruthenium dissolution. At the same time, better electrocatalytic stability and increased cO tolerance of the Pt/Ti0.8Mo0.2O2-c electrocatalyst compared to the PtRu/c catalyst was evidenced.

关键词： conducting Ti-based mixed oxides TiMoOx composite materials Pt electrocatalysts PtRu c cO-tolerance

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