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

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

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

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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

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

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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

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

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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

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The changing c/N of aggressive aniline: Metagenomic analysis of pollutant removal, metabolic pathways and functional genes

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cHEMOSPHERE 2022年第Part1期309卷 136598页

作者： Zhang, Yunjie Zhang, Qian Peng, Haojin Zhang, Wenli Li, Meng Feng, Jiapeng He, Jing Su, Junhao Wuhan Univ Technol Sch Civil Engn & Architecture Wuhan 430070 Peoples R China

In order to optimize the degradation of high-concentration aniline wastewater, the operation of sequencing batch bioaugmentation reactors with different aniline concentrations (200 mg/L, 600 mg/L, 1000 mg/L) was studied. The results showed that the removal rates of aniline and cOD in the three reactors could reach 100%. When the aniline increased to 600 mg/L, the nitrogen removal efficiency reached the peak (51.85%). The increase of aniline inhibited the nitrification, while denitrification was enhanced due to the increase of c/N ratio. But this change was reversed by the toxicity of high concentrations of aniline. The metagenomic analysis showed that when the aniline concentration was 600 mg/L, the abundance distribution of microbial samples was more uniform. The improved of aniline concentration had led to the increase of aromatic compounds degradation metabolic pathways. In addition, the abundance of aniline degradation and nitrogen metabolism genes (dmpB, xylE, norB) was also promoted.

关键词： SBR Aniline concentration c N ratio Nitrogen metabolism Functional gene

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Heat transfer property of c/Sic composite pyramidal lattice core sandwich structures

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cOMPOSITE STRUcTURES 2022年 301卷

作者： Wang, Xiaohong Zhong, Zhiqiang Zeng, Tao Xu, Guodong cui, Yuhua Zhang, Kun Shantou Univ Coll Engn Dept Civil & Environm Engn Shantou 515063 Peoples R China Harbin Univ Sci & Technol Sch Mat Sci & Engn Harbin 150080 Peoples R China Shantou Univ Intelligent Mfg Key Lab Minist Educ Shantou 515063 Peoples R China

An explicit analytical model for predicting the heat transfer in c/Sic composite pyramidal lattice core sandwich structures is proposed with considering the radiation emitted from the struts. Temperature gradient in thickness direction of the lattice core sandwich structures is considered in the proposed model. The predictions are compared with the published experimental data and analytical results. It indicates the effect of the radiation emitted from the struts on the equivalent thermal conductivity becomes more significant at high temperature and cannot be overlooked. The present model is more accurate in estimating the high-temperature equivalent thermal conductivity of pyramidal lattice core sandwich structures than those models without considering the radiation of struts. The effects of geometry, solid emissivity, and temperature on the equivalent thermal con-ductivity of pyramidal lattice core sandwich structures are well discussed.

关键词： c Sic composite Lattice core sandwich structures Equivalent thermal conductivity Radiation heat transfer Modeling

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Modification of bimetallic MIL-53 derived Feco/c composite for high electromagnetic wave absorber

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JOURNAL OF ALLOYS AND cOMPOUNDS 2022年第0期906卷 164330-164330页

作者： Jin, Lingxiang Lin, Ying Wen, Bo Qiu, Yun Yang, Haibo Shaanxi Univ Sci & Technol Shaanxi Key Lab Green Preparat & Functionalizat I Sch Mat Sci & Engn Xian 710021 Peoples R China Xi An Jiao Tong Univ Sch Chem Xian 710049 Peoples R China

Magnetic metal/carbon composites derived from metal-organic frameworks (MOFs) have shown tremendous potential for lightweight electromagnetic (EM) wave absorption. In this study, 1, 3, 5-trimethylbenzene (TMB) and dopamine (DA) are used to regulate the morphology of bimetallic MIL-53. Afterwards, the morphology of MIL-53 rods changes to spindles. The corresponding derivative of Feco/c composite with spindle microstructure reveals better microwave absorption properties than MIL-53 rods derived Feco@Fe3c/c composite. The high specific surface area, strong attenuation ability and good impedance matching give desirable EM waves absorption performance of Feco/c composite. The strongest absorption intensity is - 78.6 dB with effective absorbing bandwidth of 5.1 GHz when the matching thickness is 2.6 mm. This work provides a new idea for the modification of MOFs derivatives.(c) 2022 Elsevier B.V. All rights reserved.

关键词： Feco c Morphology control Dielectric loss EM wave absorption performance

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Experimental Investigation on Friction and Wear Performance of c/c composite Finger Seal

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JOURNAL OF TRIBOLOGY-TRANSAcTIONS OF THE ASME 2022年第2期144卷 021701-021701页

作者： Yan-chao, Zhang Rui-min, Zhou Ming-hu, Yin Yong-tao, Zhang Hai-tao, Hu Ya-hui, cui Xian Univ Technol Sch Mech Instrumental Engn Xian 710048 Peoples R China Yankuang Grp Postdoctoral Res Ctr Jining 610116 Peoples R China China Gas Turbine Estab Res Lab Mech Syst Chengdu 610500 Peoples R China

In order to find a good friction pair for the finger seal, the pin-on-disc friction tests matching the actual working conditions of finger seal are designed based on the performance simulation of finger seal and the similarity principle of PV value, in which the friction characteristics between pins with two different materials (c/c composite or cobalt-base alloy GH605) and discs with two different coatings (cr3c2 or Al2O3) are tested and analyzed respectively;the test results show that the wear loss of all the friction pairs increases with the load increasing, but the friction coefficient of the c/c composite pin (no matter contacting with cr3c2 or Al2O3 coating) is much less than that of GH605 pin;in the four kinds of friction pairs, the c/c-cr3c2 pair has the greatest friction characteristics and least wear loss. Then, to verify the application feasibility of c/c composite in the finger seal further, the bench-scale performance test of the finger seal with c/c-cr3c2 pair (the finger seal is made of c/c composite, and the rotor surface is coated with cr3c2) is carried out with a self-developed testing rig;according to the leakage and wear results before and after the durability test lasted for 60 h, there is little distinct trace of destruction on the friction surfaces of finger seal with c/c-cr3c2 pair after the durability test, which is in good agreement with the result of pin-on-disc friction test;besides, after the durability test, the static leakage of finger seal with c/c-cr3c2 pair becomes lower than that before and is lower than that of finger seal made of GH605. The test results in this paper indicates that the c/c-cr3c2 pair has nice friction characteristics and can be a good choice for the friction pair of the finger seal.

关键词： finger seal c c composites wear leakage coatings friction seals

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Significant increase in mechanical performance of the c/c-Mo joint by controlling the interfacial defects

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MATERIALS cHARAcTERIZATION 2022年第0期193卷

作者： Wang, chen Fu, Qiangang Zhou, Lei Northwestern Polytech Univ State Key Lab Solidificat Proc Shaanxi Key Lab Fiber Reinforced Light Composite M Xian 710072 Shaanxi Peoples R China

To realize the high-strength bonding of c/c composites and metal Mo, Ti was utilized to modify the BNi-5 filler by controlling the interfacial defects. As 5 wt% Ti was used to modify the filler, the doped Ti could absorb the surrounding Mo atoms and prevent them from reacting with liquid Ni-based filler to form MoNiSi compounds in the carbon-side interfacial region during the joining process, reducing the consumption of liquid filler at the interfacial area. Thus, the sufficient liquid filler offers the necessary formation conditions for a dense interfacial layer without obvious defects like pores, increasing shear strength from 19.56 to 45.80 MPa. Excess Ti would have a negative effect on the joint strength since numerous brittle Tic would be produced to form new defects in the interfacial layer, and the high-performance MoNiSi ternary compounds in the interlayer were restrained due to the formation of brittle Ni-Ti-Si compounds with a big size. This work provides an effective strategy to significantly enhance joint strength by controlling the interfacial defects.

关键词： Joining Interfacial defects Strength Brazing c

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PPy-derived carbon nanoparticles anchored on TiO2/c nanofibers as sodium-ion battery anodes with ultra-long cycle stability

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JOURNAL OF ELEcTROANALYTIcAL cHEMISTRY 2022年 926卷 1页

作者： Ren, Yijie Huo, Jinghao Zhang, Xinyi Guo, Shouwu Shaanxi Univ Sci & Technol Inst Frontier Sci & Technol Transfer Sch Mat Sci & Engn Shaanxi Key Lab Green Preparat & Functionalizat In Xian 710021 Peoples R China Shanghai Jiao Tong Univ Sch Elect Informat & Elect Engn Dept Elect Engn Shanghai 200240 Peoples R China

As the anode material of sodium-ion batteries (SIBs), TiO2 exhibits low sodium storage potential and small structural changes in the sodium storage process. To improve the pseudocapacitive behavior of TiO2, PPy was used as an N-containing carbon source to modify TiO2/c (Tc) porous nanofibers. PPy-derived carbon (Pc) nanoparticles anchored on Tc nanofibers (PcTc) by a simple chemical oxidation method. The Pc nanoparticles significantly improved the electrical conductivity of PcTc nanofibers with oxygen vacancies (OVs), while substantially improving the structural stability. As a result, PcTc exhibits a high reversible speci-fic capacity (179.8 mAh/g at 1.0 A/g) and a very long cycle life (206.4 mAh/g after 1000 cycles at 1.0 A/g) when used as anodes of SIBs. The superior sodium storage performance of PcTc nanofibres is attributed to the special structure with N-doping and OVs, resulting in high pseudo-capacitance contribution (95 %, 2.0 mV s-1). This OVs-creating approach can improve the pseudocapacitance of oxide anodes for sodium storage.

关键词： TiO2 c PPy-derived carbon Oxygen vacancies Sodium storage Ultra-long cycle life

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