检索结果-内蒙古大学图书馆

changes in microstructure and mechanical properties of the carbon fiber and their effects on c/Sic composites

MATERIALS cHARAcTERIZATION 2022年第0期193卷

作者： Hao, Jianjie Li, Jiayan Shi, Xiaolei He, Ping Shi, Wei Tan, Yi Dalian Univ Technol Key Lab Mat Modificat Laser Ion & Electron Beams Minist Educ Dalian 116024 Peoples R China Dalian Univ Technol Sch Mat Sci & Engn Dalian 116024 Peoples R China Chinese Acad Sci Inst Met Res Shenyang 110016 Peoples R China Chinese Acad Sci Shanghai Inst Ceram State Key Lab High Performance Ceram & Superfine M Shanghai 200050 Peoples R China

The changes in microstructure and mechanical properties of the carbon fiber and their effects on c/Sic composites were studied. The H, N and O atoms escaped and the carbon content in the carbon fiber increased when the heat treatment temperature exceeds 1200 degrees c. Meanwhile, the growth of graphite crystallite leaded to stress concentration and reduced the tensile strength of carbon fiber to 2.98 GPa by 1200 degrees c heat treatment. The active atoms on the surface of the carbon fiber were reduced, thus weakening the bonding force between the carbon fiber and the pyrolytic carbon interface layer and improving the pullout mechanism of the carbon fiber. This result was also observed by synchrotron radiation X-ray computed tomography. The flexural strength of the c/ Sic composite increased from 300 MPa without treatment to 364 MPa after 1600 degrees c heat treatment.

关键词： carbon fiber Heat treatment Tensile strength c Sic composites

来源：评论

学校读者我要写书评

暂无评论

Fast-tracking of NH3 interaction with ZnO nanorods and c/ZnO hybrid nanostructures by operando spectroscopy

引用

APPLIED SURFAcE ScIENcE 2022年 590卷 153067-153067页

作者： Mbuyisa, Puleng N. Rigoni, Federica Nappini, Silvia Magnano, Elena Pagliara, Stefania Drera, Giovanni Sangaletti, Luigi Goldoni, Andrea Ndwandwe, Muzi cepek, cinzia Univ Zululand Dept Phys & Engn Private Bag X1001 ZA-3886 Kwa Dlangezwa South Africa Univ Cattolica Sacro Cuore Interdisciplinary Labs Adv Mat Phys Via Musei 41 I-25121 Brescia Italy Univ Cattolica Sacro Cuore Dipartimento Matemat & Fis Via Musei 41 I-25121 Brescia Italy Ist Officina Mat CNR Lab TASC Ss 14Km 163-4 I-34149 Trieste Italy Elettra Sincrotrone Trieste SCpA Ss 14Km 163 I-34149 Trieste Italy Ca Foscari Univ Venice Dept Mol Sci & Nanosyst Via Torino 155 I-30170 Venice Italy Univ Johannesburg Dept Phys POB 524Auckland Pk ZA-2006 Johannesburg South Africa

Fast X-ray photoemission spectroscopy has been carried out to track the interaction of ammonia gas with hybrid materials based on ZnO nanorods and nanostructured carbon. We provide, for the first time, direct evidence of gas adsorption of ammonia on nanostructured hybrid interfaces combining photoemission with transport measurements through the resistivity change upon gas exposure. This operando methodology allowed us to reconstruct the adsorption isotherms and relate the different behavior to the sample morphology at the nanoscale. While on bare ZnO nanorods, physisorption of ammonia is detected along with photon beam assisted cracking, on the nanostructured carbon the formation of amine groups is detected, without displaying any effect induced by photon beam exposure. Our results make the present experiment an operando general methodology, with the possibility to relate the transport versus dose curves (ultimately the adsorption isotherms) to a specific investigation of the gas/surface interactions.

关键词： ZnO c ZnO hybrid NH (3) gas fast acquisition XPS Adsorption isotherms Resistance

来源：评论

学校读者我要写书评

暂无评论

comparative research on cyclic ablation behavior of c/c-Zrc-Sic and c/ c-Zrc composites at temperatures above 2000?c

引用

cORROSION ScIENcE 2022年 206卷

作者： Zhao, Zhigang Li, Kezhi Kou, Gang Li, Wei Northwestern Polytech Univ Carbon Carbon Composites Res Ctr Xian 710072 Peoples R China Xian Aeronaut Univ Sch Mat Engn Xian 710077 Peoples R China

The cyclic and single ablation behavior of c/c-Zrc-Sic and c/c-Zrc composites prepared by reactive melt infiltration were studied. The ablation resistance properties of cyclic ablation of 30 s x 4 and single ablation of 120 s was similar to that of 60 s x 4 and 240 s. The oxidation of the matrix and the peeling content of oxides are aggravated with the increased cyclic ablation numbers. Under the cyclic ablation mode, c/c-Zrc-Sic composites showed lower mass loss than c/c-Zrc composites. At the single ablation of 240 s, c/c-Zrc-Sic composites showed desirable ablation resistance owing to the formation of an effective heat/oxygen protection layer on the ablated surface.

关键词： carbon carbon composites c c-Zrc-Sic composites Reactive melt infiltration Ultrahigh temperature cyclic ablation

来源：评论

学校读者我要写书评

暂无评论

Effect of impact damage on electrical resistivity of c/c-Sic composites

引用

INTERNATIONAL JOURNAL OF MATERIALS RESEARcH 2022年第8期94卷 930-933页

作者： Srivastava, V. K. Maile, K. Bothe, K. Udoh, A. Univ Stuttgart Staatliche Mat Stuttgart Germany Banaras Hindu Univ Dept Mech Engn Varanasi Uttar Pradesh India

The main objective of the present work was to study the low-velocity weight-drop impact damage behaviour of carbon - carbon silicon carbide (c/c- Sic) composites on electrical resistivity of the direct-current potential drop method. The results show that the electrical resistivity increases with increasing impact energy, which confirms that pre-microcracks of c/c- Sic composite grow very rapidly with a little amount of impact load and turn into a loss of conductivity of the material.

关键词： c c- Sic composites Weight-drop impact energy Indentation Electrical resistivity Damage Lockin thermography

来源：评论

学校读者我要写书评

暂无评论

Insights into deterioration and reactivation of a mainstream anammox biofilm reactor response to c/N ratio

引用

JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022年 320卷 115780页

作者： chen, Jiabo Hai, Yan Zhang, Wei Zhou, Xin Taiyuan Univ Technol Coll Environm Sci & Engn Taiyuan 030024 Peoples R China Innovat Ctr Postgrad Educ Municipal Engn Shanxi Pr Taiyuan 030024 Peoples R China Renmin Univ China Res Ctr Low Carbon Technol Water Environm Sch Environm & Nat Resources Beijing 100872 Peoples R China

In-depth knowledge of the deterioration and reactivation of the anaerobic ammonium oxidation (anammox) induced by carbon-to-nitrogen (c/N) is still lacking. Herein, the anammox performance was investigated in an anaerobic sequence biofilm batch reactor fed with low-strength partial nitration effluent in the range of c/N ratio from 0.5 to 3. The anammox was hardly deteriorated at c/N lower than 1.5, while became worsen if c/N was above 2.0. The specific anammox activity (SAA) experiments showed an 85% decrease of SAA at c/N of 3.0 compared with the maximum value (c/N:0). However, anammox capacity was rapidly recovered once influent c/N was adjusted back to zero. Moreover, c/N also highly affected the composition, structure and function of extracellular polymeric substance of the anammox biofilm. High-throughput sequencing revealed a close cor-relation between c/N change and microbial structure shift. Finally, the potential inhibition and restoration mechanism of the c/N-dependent anammox were proposed based on metagenomic analysis. This research provides some insights into the reinstatement of a mainstream anammox biofilm process after it is interrupted by high c/N influent.

关键词： Anammox Inhibition Recovery c N ratio Extracellular polymeric substance Microbial community

来源：评论

学校读者我要写书评

暂无评论

Lithium Vacancy-Tuned [cuO4] Sites for Selective cO2 Electroreduction to c2+ Products

引用

SMALL 2022年第8期18卷 2106433-2106433页

作者： Peng, chen Zhu, Xiaorong Xu, Zikai Yan, Shuai chang, Lo Yueh Wang, Zhiqiang Zhang, Junbo chen, Menghuan Sham, Tsun-Kong Li, Yafei Zheng, Gengfeng Fudan Univ Dept Chem Adv Mat Lab Shanghai 200438 Peoples R China Fudan Univ Fac Chem & Mat Sci Shanghai Key Lab Mol Catalysis & Innovat Mat Shanghai 200438 Peoples R China Nanjing Normal Univ Sch Chem & Mat Sci Jiangsu Collaborat Innovat Ctr Biomed Funct Mat Jiangsu Key Lab New Power Batteries Nanjing 210023 Peoples R China Soochow Univ Joint Int Res Lab Carbon Based Funct Mat & Devic Inst Funct Nano & Soft Mat FUNSOM Suzhou 215123 Jiangsu Peoples R China Univ Western Ontario Dept Chem 1151 Richmond St London ON N6A 5B7 Canada

Electrochemical cO2 reduction to valuable multi-carbon (c2+) products is attractive but with poor selectivity and activity due to the low-efficient c-c coupling. Herein, a lithium vacancy-tuned Li2cuO2 with square-planar [cuO4] layers is developed via an electrochemical delithiation strategy. Density functional theory calculations reveal that the lithium vacancies (V-Li) lead to a shorter distance between adjacent [cuO4] layers and reduce the coordination number of Li+ around each cu, featuring with a lower energy barrier for cO-cO coupling than pristine Li2cuO2 without V-Li. With the V-Li percentage of approximate to 1.6%, the Li2-xcuO2 catalyst exhibits a high Faradaic efficiency of 90.6 +/- 7.6% for c2+ at -0.85 V versus reversible hydrogen electrode without iR correction, and an outstanding partial current density of -706 +/- 32 mA cm(-2). This work suggests an attractive approach to create controllable alkali metal vacancy-tuned cu catalytic sites toward c2+ products in electrochemical cO2 reduction.

关键词： c (2+) products cO (2) reduction reaction electrochemical delithiation Li 2cuO (2) lithium vacancies

来源：评论

学校读者我要写书评

暂无评论

Effect of Single Loading Time to the cyclic Ablation of c/c-Sic-Zrc composite

引用

MATERIALS 2022年第19期15卷 7027-7027页

作者： Feng, Wei Wang, Xinyu Tian, Yunlong Liu, Lei Li, Boyan Xian Technol Univ Sch Mat & Chem Engn Xian 710021 Peoples R China

To understand the influence of single loading time on the cyclic ablation of carbide modified c/c composites, a c/c-Sic-Zrc composite was impacted by plasma at 2600 K for 50 s under reciprocating 0.5 (c-0.5) and 5 s (c-5), respectively. The composites displayed similar negative mass and rising positive linear ablation rates from c-0.5 to c-5. Phases, micro-morphologies, and surface temperature analysis suggested that the partially oxidized Sic-Zrc covering on the ablated sample cracked and was persistently peeled off. The mass gain resulted from the ceramic's protection of the nearby carbon from complete oxidation. The longer single loading of 5 s caused strengthened thermal chemical reaction and mechanical erosion, which resulted in the bigger linear loss.

关键词： cyclic ablation single loading time c c composite Sic-Zrc plasma

来源：评论

学校读者我要写书评

暂无评论

Nutrient Resorption and c:N:P Stoichiometry Responses of a Pinus massoniana Plantation to Various Thinning Intensities in Southern china

引用

FORESTS 2022年第10期13卷 1699-1699页

作者： Jiang, Jun Lu, Yuanchang chen, Beibei Ming, Angang Pang, Lifeng Beijing Forestry Univ Coll Forestry Beijing 100083 Peoples R China Res Ctr Forest Management Engn State Forestry & G Beijing 100083 Peoples R China Chinese Acad Forestry Expt Ctr Trop Forestry Pingxiang 532699 Peoples R China Chinese Acad Forestry Inst Forest Resource Informat Tech Beijing 100091 Peoples R China

Understanding the responses of c:N:P stoichiometry and nutrient resorption to thinning is essential to evaluate the effects of management practices on biogeochemical cycling in plantation forest ecosystems. However, nutrient resorption and c:N:P stoichiometry do not always respond in the same way to various thinning intensities, and the underlying mechanisms are not well understood. In this study, we aimed to examine the mechanisms underlying the impacts of thinning on c:N:P stoichiometry in a Pinus massoniana plantation, focusing on interactions among soils, plant tissues (leaves and litter), and soil properties. We conducted four different thinning treatments to determine the effects of thinning on the c:N:P stoichiometric ratios in leaves, litter, and soil in a Pinus massoniana plantation ecosystem. Thinning significantly increased the c, N, and P content of leaves, litter, and soil (p < 0.05). The effects of thinning on c:N:P stoichiometry varied strongly with thinning intensity. Specifically, thinning significantly decreased all c:N:P stoichiometry except leaf N:P and litter c:N (p < 0.05). The N resorption efficiency (NRE) showed no significant change, but thinning significantly decreased the P resorption efficiency (PRE, p < 0.05). This suggests that thinning has inconsistent impacts on N and P cycling in Pinus massoniana plantations. In addition, these different responses suggest that soil physicochemical processes play a crucial role in regulating the effects of thinning. Thinning intensity regulates the biogeochemical cycles of c, N, and P in Pinus massoniana plantation ecosystems by affecting nutrient resorption and soil physicochemical processes. The inconsistent results obtained can be attributed to the complexities of stand environments and the redistribution of site resources following thinning. Therefore, incorporating the effects of thinning intensity into nutrient cycling models may improve predictions related to achieving long-term forest manageme

关键词： thinning intensity Pinus massoniana plantation c N P stoichiometry nutrient resorption efficiency

来源：评论

学校读者我要写书评

暂无评论

Investigating the Role of Gravity Waves on Equatorial Ionospheric Irregularities Using TIMED/SABER and c/NOFS Satellite Observations

引用

ATMOSPHERE 2022年第9期13卷 1414-1414页

作者： Nigussie, Melessew Moldwin, Mark Yizengaw, Endawoke Bahir Dar Univ Sci Coll Phys Dept Washera Geospace & Radar Sci Res Lab POB 79 Bahir Dar Ethiopia Univ Michigan Dept Climate & Space Sci & Engn Ann Arbor MI 48108 USA Aerosp Corp Space Sci Applicat Lab El Segundo CA 90245 USA

In this paper, for the first time, simultaneous atmospheric temperature perturbation profiles obtained from the TIMED/SABER satellite and equatorial ion density and vertical plasma drift velocity observations with and without ESF activity obtained from the c/NOFS satellite are used to investigate the effect of gravity waves (GW) on ESF. The horizontal and vertical wavelengths of ionospheric oscillations and GWs are estimated by applying wavelet analysis techniques. In addition, vertically propagating GWs that dissipate energy in the ionosphere-thermosphere system are investigated using the spectral analysis technique. We find that the vertical wavelength of GW, corresponding to dominant wavelet power, ranges from 12 to 31 km regardless of the conditions of the ionosphere;however, GWs with vertical wavelengths between about 1 to 13 km are found every day, saturated between 90 and 110 km at different longitudinal sectors. Filtering out vertical wavelengths above 13 km from temperature perturbations, ranges of zonal wavelengths of GW (i.e., from about 290 to 950 km) are found corresponding to irregular and non-irregular ionosphere. Similarly, corresponding to dominant oscillations, the zonal wavelength of ion density perturbations is found within 16 to 1520 km. Moreover, we find an excellent agreement among the median zonal wavelengths of GW for the cases of irregular and non-irregular ionosphere and ion density perturbations that are 518, 495, and 491 km, respectively. The results imply that seed perturbations due to GW with a vertical wavelength from about 1 to 13 km evolve to ion density irregularity and may be amplified due to post-sunset vertical upward drift velocity.

关键词： gravity wave equatorial spread F c NOFS satellite SABER satellite

来源：评论

学校读者我要写书评

暂无评论

The Effect of c/Si Ratio and Fluorine Doping on the Gas Permeation Properties of Pendant-Type and Bridged-Type Organosilica Membranes

引用

MEMBRANES 2022年第10期12卷 991-991页

作者： Rana, Ikram Nagaoka, Takahiro Nagasawa, Hiroki Tsuru, Toshinori Kanezashi, Masakoto Hiroshima Univ Dept Chem Engn Separat Engn Lab Higashihiroshima 7398527 Japan

A series of pendant-type alkoxysilane structures with various carbon numbers (c-1-c-8) were used to fabricate sol-gel derived organosilica membranes to evaluate the effects of the c/Si ratio and fluorine doping. Initially, this investigation was focused on the effect that carbon-linking (pendant-type) units exert on a microporous structure and how this affects the gas-permeation properties of pendant-type organosilica membranes. Gas permeation results were compared with those of bridged-type organosilica membranes (c-1-c-8). Network pore size evaluation was conducted based on the selectivity of H-2/N-2 and the activation energy (E-p) of H-2 permeation. consequently, E-p (H-2) was increased as the c/Si ratio increased from c-1 to c-8, which could have been due to the aggregation of pendant side chains that occupied the available micropore channel space and resulted in the reduced pore size. By comparison, these permeation results indicate that pendant-type organosilica membranes showed a somewhat loose network structure in comparison with bridged-type organosilica membranes by following the lower values of activation energies (E-p). Subsequently, we also evaluated the effect that fluorine doping (NH4F) exerts on pendant-type [methytriethoxysilane (MTES), propyltrimethoxysilane (PTMS)] and bridged-type [1,2-bis(triethoxysilyl)methane (BTESM) bis(triethoxysilyl)propane (BTESP)] organosilica structures with similar carbon numbers (c-1 and c-3). The gas-permeation properties of F-doped pendant network structures revealed values for pore size, H-2/N-2 selectivity, and E-p (H-2) that were comparable to those of pristine organosilica membranes. This could be ascribed to the pendant side chains, which might have hindered the effectiveness of fluorine in pendant-type organosilica structures. The F-doped bridged-type organosilica (BTESM and BTESP) membranes, on the other hand, exhibited a looser network formation as the fluorine concentration increased.

关键词： organosilica membranes c Si ratio fluorine doping network pore size gas permeation properties

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：