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Size effect of carbon fiber-reinforced silicon carbide composites (c/c-Sic): Part 1-bending load and statistical effects

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JOURNAL OF THE EUROPEAN cERAMIc SOcIETY 2021年第14期41卷 6805-6814页

作者： Flauder, Stefan Langhof, Nico Krenkel, Walter Schaffoener, Stefan Univ Bayreuth Ceram Mat Engn CME Prof Rudiger Bormann Str 1 D-95447 Bayreuth Germany

This study analyzed the influence of the sample volume, number of tested specimen, and testing method on the flexural strength of fabric-reinforced ceramic matrix composites. For this purpose, seven different batches of c/cSic were prepared with four different sample thicknesses to determine the flexural strengths and Weibull moduli by three-and four-point flexural tests. The result showed that c/c-Sic exhibits a size effect of strength under bending load because a decrease of measured flexural strength with increased specimen size was observed. This size effect was discussed regarding the Weibull weakest link approach and the concept of quasi-brittle materials. The determined Weibull moduli were comparable for the same load condition but dissimilar for the identical material if the load condition were changed from three-to four-point bending. Hence, the Weibull modulus was found to be not an inherent material constant for c/c-Sic and the Weibull weakest link approach seems not appropriate.

关键词： ceramic matrix composites (cMc) Bending test Weibull statistics c c-Sic Size effect of strength

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Short stature explained by dimerization of human growth hormone induced by a p.c53S point mutation

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JOURNAL OF BIOLOGIcAL cHEMISTRY 2020年第15期295卷 4893-4901页

作者： Sander, Max Wu Zida Strasburger, christian J. Univ Med Berlin Dept Endocrinol Diabet & Nutr Med Campus Charite MitteCharitepl 1 D-10117 Berlin Germany

A homozygous mutation in growth hormone 1 (GH1) was recently identified in an individual with growth failure. This mutation, c.705G>c, causes replacement of cysteine at position 53 of the 191-amino-acid sequence of 22 kDa human GH (hGH) with serine (p.c53S). This hGH molecule (hereafter referred to as GH-c53S) lacks the disulfide bond between ***-53 and ***-165, which is highly conserved among species. It has been reported previously that monomeric GH-c53S has reduced bioactivity compared with WT GH (GH-WT) because of its decreased ability to bind and activate the GH receptor in vitro. In this study, we discovered that substitution of ***-53 in hGH significantly increased formation of hGH dimers in pituitary cells. We expressed His-tagged hGH variants in the cytoplasm of genetically modified Rosetta-gami B DE3 Escherichia coli cells, facilitating high-yield production. We observed that the bioactivity of monomeric GH-c53S is 25.2% of that of GH-WT and that dimeric GH-c53S?His has no significant bioactivity in cell proliferation assays. We also found that the expression of GH-c53S in pituitary cells deviates from that of GH-WT. GH-c53S was exclusively stained in the Golgi apparatus, and no secretory granules formed for this variant, impairing its stimulated release. In summary, the unpaired cys-165 in GH-c53S forms a disulfide bond linking two hGH molecules in pituitary cells. We conclude that the GH-c53S dimer is inactive and responsible for the growth failure in the affected individual.

关键词： growth hormone disulfide dimerization pituitary gland protein folding c 705G>c cysteine GH-c53S growth hormone deficiency

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THE INHIBITION OF PHOTOcHEMIcAL SMOG .9. MODEL-cALcULATIONS OF THE EFFEcT OF (c2H5)2NOH ON c2H4-NOX ATMOSPHERES

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ATMOSPHERIc ENVIRONMENT 1985年第4期19卷 597-605页

作者： HEIcKLEN, J PENN STATE UNIV CTR AIR ENVIRONM STUDIES UNIVERSITY PK PA 16802 USA

computer modeling of c2H4-NOx atmospheres with and without (c2H5)2NOH present were performed. The reaction scheme consists of 102 reactions and 45 reaction species plus N2, which is unreactive. No perceptible reaction occurs unless HNO2 is present, which can photodecompose to give HO radicals. HNO2 is produced from the reaction of H2O, NO and NO2. The equilibrium apparently is rapidly maintained through heterogeneous reactions. For systems with no H2O present, an artificial HO-source term must be included. A number of calculations for c2H4-NOx systems were made for conditions of various dilution factors, (c2H5)2NOH concentrations and feed rates, and various initial [NO]/[NO2] ratios. If NO2 is present initially it can photodecompose in air to produce a low level of O3 which in turn reacts with (c2H5)2NOH to give HO radicals. This can accelerate the onset of ultimate O3 formation. However, if sufficient (c2H5)2NOH is present or it is added before NO2 is produced, it delays O3 production. Under real atmospheric conditions which include dilution and diurnal variation in the sun''s intensity, 2nd-day effects are not important.

关键词： Photochemical smog diethylhydroxylamine model calculations environment modification c 2 H 4 -NO x atmospheres

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Simultaneous nitrogen and carbon removal in a packed A/O reactor: effect of c/N ratio on microbial community structure

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BIOPROcESS AND BIOSYSTEMS ENGINEERING 2020年第7期43卷 1241-1252页

作者： Ding, Shuai He, Jian Luo, Xingzhang Zheng, Zheng Fudan Univ Dept Environm Sci & Engn Room 2026Environm Bldg2005 Songhu Rd Shanghai 200433 Peoples R China

In this research, a novel packed anoxic/oxic moving bed biofilm reactor (MBBR) was established to achieve high-organic matter removal rates, despite the carbon/nitrogen (c/N) ratio of 2.7-5.1 in the influent. Simultaneous nitrification-denitrification (SND) was investigated under a long sludge retention time of 104 days. The system exhibited excellent performance in pollutant removal, with chemical oxygen demand and total nitrogen (TN) enhanced to 93.6-97.4% and 34.4-60%, respectively. Under low c/N conditions, the nitrogen removal process of A/O MBBR system was mainly achieved by anaerobic denitrification. The increase of c/N ratio enhanced SND rate of the aerobic section, where dissolved oxygen was maintained at the range of 4-6 mg/L, and resulted in higher TN removal efficiency. The microbial composition and structures were analyzed utilizing the MiSeq Illumina sequencing technique. High-throughput pyrosequencing results indicated that the dominant microorganisms were Proteobacteria and Bacteroidetes at the phylum level, which contributes to the removal of organics matters. In the aerobic section, abundances of Nitrospirae (1.12-29.33%), Burkholderiales (2.15-21.38%), and Sphingobacteriales (2.92-11.67%) rose with increasing c/N ratio in the influent, this proved that SND did occur in the aerobic zone. As the c/N ratio of influent increased, the SND phenomenon in the aerobic zone of the system is the main mechanism for greatly improving the removal rate of TN in the aerobic section. The c/N ratio in the aerobic zone is not required to be high to exhibit good TN removal performance. When c/NH4+ and c/TN in the aerobic zone were higher than 2.29 and 1.77, respectively, TN removal efficiency was higher than 60%, which means that carbon sources added to the reactor could be saved. This study would be vital for a better understanding of microbial structures within a packed A/O MBBR and the development of cost-efficient strategies for the treatment of low c/N wastewate

关键词： Packed A O reactor Moving bed biofilm reactor c N ratio Simultaneous nitrification-denitrification (SND) Microbial community structure

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Three-dimensional micro-pipelines high thermal conductive c/Sic composites

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cERAMIcS INTERNATIONAL 2021年第24期47卷 34333-34340页

作者： Zhang, Yunhai Liu, Yongsheng cao, Liyang Fang, Hui Liu, Bin cao, Yejie Wang, Jing chen, Jian Pan, Yu Northwestern Polytech Univ Sci & Technol Thermostruct Composite Mat Lab Xian 710072 Shaanxi Peoples R China Northwestern Polytech Univ Sch Aeronaut Xian 710072 Shaanxi Peoples R China Acad Mil Sci PLA China Natl Innovat Inst Def Technol Beijing 100071 Peoples R China Natl Univ Def Technol Coll Aerosp Sci & Engn Sci & Technol Scramjet Lab Changsha 410073 Hunan Peoples R China

carbon/silicon carbide (c/Sic) composites are usually regarded as thermal protective system materials and widely applied in hypersonic vehicles or ramjet. However, poor thermal conductivity of c/Sic composites, leading to severe heat concentration and thermal stress during the high-speed operation of hypersonic vehicle, limits their broad-range of practical applications. Modification with high thermal conductive fillers is an optional method;however, controllable dispersion and orientation of the fillers to construct continuous and ordered heat conductive channel has been proven to be a challenging task. Herein, based on high thermal conductivity fibers, a three-dimensional micro-pipeline preform was developed for the preparation of structure-function integrated c/Sic composites. The technical feasibility of the method, the characteristics of microstructures, and the thermal conductivity and bending strength of the as-obtained composites were systematically studied. Results revealed that the thermal conductivities of as-obtained composites reached 150.2 and 46.7 W m-1 K-1 for in-plane and out-of-plane direction, respectively. The bending strength obtained herein is 264.4 MPa, which is lower than that of polyacrylonitrile c/Sic composites. However, the fine control over the component and microstructure or densification could provide a higher value in the future research. In sum, the proposed method provides a convenient and feasible approach to prepare high thermal conductive c/Sic composites.

关键词： c Sic composites Micro-pipelines Thermal conductivity Bending strength Heat conductive channels

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Preparation of high performance LiFePO4/c by extracting iron element from iron tailings by concentrated sulfuric acid hot dip method

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IONIcS 2020年第4期26卷 1645-1655页

作者： Wang, Yingling Wang, Yafeng Luo, Shaohua Liu, chengjun Teng, Fei chen, Huanhuan Shen, Huiliang Gao, Desheng Northeastern Univ Sch Met Shenyang 110819 Peoples R China Northeastern Univ Minist Educ Key Lab Ecol Met Multimetall Ores Shenyang 110819 Peoples R China Northeastern Univ Qinhuangdao Sch Resources & Mat Qinhuangdao 066004 Hebei Peoples R China Northeastern Univ Sch Mat Sci & Engn Shenyang 110819 Peoples R China

LiFePO4/c cathode materials are synthesized by carbothermal reduction process using FePO4 as iron and phosphorus source, and starch as carbon source. The FePO4 precursor was prepared by leaching iron tailings with concentrated sulfuric acid and then leaching with phosphoric acid and hydrogen peroxide. The morphology and structure of FePO4 precursors prepared under different pH conditions were studied by using thermogravimetric-differential analysis (TG-DTA), infrared analysis (FTIR), x-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM). The effect of the FePO4 material on the properties of the synthesized LiFePO4 cathode was investigated by charge and discharge cycles. On this basis, the effects of different molar ratios of c and LiFePO4 on the performance of synthetic product LiFePO4/c were studied using starch as carbon source. The results show that the FePO4 precursor prepared under the condition of pH 2 is the raw material, and the LiFePO4/c cathode material synthesized by adding 45% carbon has the best performance. The first cycle discharge capacity reached 142.6 mAh g(-1) at a current density of 0.1 degrees c, reaching 83.9% of its theoretical capacity. This work proposes a novel and effective method to utilize the iron tailings.

关键词： cathode material LiFePO4 c Iron tailings concentrated sulfuric acid leaching FePO4 precursor

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Elevated efficiency of c₃ photosynthesis in bamboo grasses: A possible consequence of enhanced refixation of photorespired cO₂

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GLOBAL cHANGE BIOLOGY BIOENERGY 2021年第6期13卷 941-954页

作者： Peixoto, Murilo M. Sage, Tammy L. Busch, Florian A. Pacheco, Haryel D. N. Moraes, Moemy G. Portes, Tomas A. Almeida, Rogerio A. Graciano-Ribeiro, Dalva Sage, Rowan F. Univ Fed Goias Programa Posgrad Biodiversidade Vegetal Inst Ciencias Biol Goiania Go Brazil Univ Toronto Dept Ecol & Evolutionary Biol 25 Willcocks St Toronto ON M5S 3B2 Canada Univ Birmingham Birmingham Inst Forest Res Sch Biosci Birmingham W Midlands England Univ Fed Goias Escola Agron Goiania Go Brazil Washington State Univ Sch Biol Sci Pullman WA 99164 USA

Bamboos are productive grasses that currently yield a high-quality wood and potentially an abundance of lignocellulose for bioenergy. All are c-3 grasses of warm habitats, where they are prone to significant photorespiratory inhibition and competitive suppression by c-4 grasses. Here, we investigate whether three bamboo species from the Brazilian cerrado (Dendrocalamus asper, Guadua angustifolia, and Guadua magna) exhibit unique adaptations that suppress photorespiratory costs and enhance photosynthetic efficiency. We evaluated photosynthetic efficiency of the bamboos and rice (Oryza sativa) by measuring c-*, the cO2 compensation point in the absence of mitochondrial respiration. At 25celcius, c-* averaged 2.81 Pa in each of the bamboo species, which is closer to a c-2 plant (2.71 Pa) than the c-3 plant rice (3.31 Pa). Assuming a chloroplast cO2 concentration of 200 mu mol mol(-1), this represents an 18% lower cost of apparent photorespiration in bamboo than rice. Light and transmission electronic microscopy of the bamboo leaves exhibited few organelles in the bundle and mestome sheath cells, and mesophyll (M) cells are deeply lobed with 99% of the cell periphery adjacent to intercellular air space covered by chloroplast and stromules. The chloroplast layer in bamboo M cells is thick, with mitochondria adjacent to or engulfed by chloroplasts. This arrangement slows cO2 efflux and facilitates refixation of photorespired cO2, which could explain the low c-* in the bamboos. The bamboos also had higher water use efficiency than rice, which may reflect efficient refixation of photorespired cO2.

关键词： Bambuseae c (*) c-3 photosynthesis cO2 refixation Dendrocalamus Guadua photorespiration water use efficiency

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Ordered Element Distributed c3N Quantum Dots Manipulated crystallization Kinetics for 2D csPbI3 Solar cells with Ultra-High Performance

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SMALL 2022年第15期18卷 2108090-2108090页

作者： Li, Zhizai Yang, Siwei Ye, caichao Wang, Gang Ma, Bo Yao, Huanhuan Wang, Qian Peng, Guoqiang Wang, Qiang Zhang, Hao-Li Jin, Zhiwen Lanzhou Univ Sch Phys Sci & Technol Lanzhou 730000 Peoples R China Lanzhou Univ Key Lab Magnetism & Magnet Mat MoE Lanzhou 730000 Peoples R China Chinese Acad Sci Shanghai Inst Microsyst & Informat Technol State Key Lab Funct Mat Informat Lab Graphene Mat & Applicat Shanghai 200050 Peoples R China Univ Chinese Acad Sci Coll Mat Sci & Optoelect Technol Beijing Peoples R China Southern Univ Sci & Technol Acad Adv Interdisciplinary Studies Shenzhen 518055 Guangdong Peoples R China Southern Univ Sci & Technol Guangdong Prov Key Lab Computat Sci & Mat Design Shenzhen 518055 Guangdong Peoples R China Ningbo Univ Sch Phys Sci & Technol Dept Microelect Sci & Engn Ningbo 315211 Peoples R China Lanzhou Univ State Key Lab Appl Organ Chem Lanzhou 730000 Peoples R China Lanzhou Univ Key Lab Special Funct Mat & Struct Design Lanzhou 730000 Peoples R China Lanzhou Univ Coll Chem & Chem Engn Lanzhou 730000 Peoples R China

Two-dimensional (2D) csPbI3 is developed to conquer the phase-stability problem of csPbI3 by introducing bulky organic cations to produce a steric hindrance effect. However, organic cations also inevitably increase the formation energy and difficulty in crystallization kinetics regulation. Such poor crystallization process modulation of 2D csPbI3 leads to disordered phase-arrangement, which impedes the transport of photo-generated carriers and worsens device performance. Herein, a type of c3N quantum dots (QDs) with ordered carbon and nitrogen atoms to manipulate the crystallization process of 2D csPbI3 for improving the crystallization pathway, phase-arrangement and morphology, is introduced. combination analyses of theoretical simulation, morphology regulation and femtosecond transient absorption (fs-TA) characterization, show that the c3N QDs induce the formation of electron-rich regions to adsorb bulky organic cations and provide nucleation sites to realize a bi-directional crystallization process. Meanwhile, the quality of 2D csPbI3 film is improved with lower trap density, higher surface potential, and compact morphology. As a result, the power conversion efficiency (PcE) of the optimized device (n = 5) boosts to an ultra-high value of 15.63% with strengthened environmental stability. Moreover, the simple c3N QDs insertion method shows good universality to other bulky organic cations of Ruddlesden-Popper and Dion-Jacobson, providing a good modulation strategy for other optoelectronic devices.

关键词： 2D csPbI (3) c N-3 crystallization kinetics phase management

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3D In-Situ characterizations of Damage Evolution in c/Sic composite under Monotonic Tensile Loading by Using X-Ray computed Tomography

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APPLIED cOMPOSITE MATERIALS 2020年第3期27卷 119-130页

作者： Wang, Long Zhang, Wei Li, Haibo Hou, chuantao Ren, Fang Beijing Inst Struct & Environm Engn Sci & Technol Reliabil & Environm Engn Lab 1 South Dahongmen Rd Beijing 100076 Peoples R China

The damage evolution and fracture behavior in the bulk of c/Sic material under monotonic tensile loading have been investigated with the 3D in-situ observations by using X-ray cT. crack initiated inside the matrix within 0.02 mm below surface when the load was only 19% of the failure strength, and propagated to the surface of matrix and towards the interior of specimen by breaking fibers and matrix when the load was above the elastic limit. With the further increasing of loading, other fiber breaks, matrix breaks and delaminations were observed to initiate and propagate both on the surface and in the bulk of specimen, while the cracks nucleating in the bulk of specimen are generally located at the laminae with a high volume fraction of pores. With the further propagations of cracks, the specimen split in the laminae with a large quantity of pores, while the fiber drawings results in the final fracture in the laminae without a large quantity of pores. The novel method being proposed to characterize the distribution of pores in this paper highlights the relation between the distribution of pores in the bulk of the studied material and cracks initiations and final fracture.

关键词： X-ray computed tomography In-situ observations c Sic composite Damage evolution Fracture

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Waste biomass derived carbon supported Mo2c/c composite materials for heavy metal adsorption and hydrogen evolution reaction

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MATERIALS TODAY cOMMUNIcATIONS 2022年 31卷

作者： Ding, Jun He, Wenzhi Yu, chao Liu, Zhenglong Deng, chengji Zhu, Hongxi Wuhan Univ Sci & Technol State Key Lab Refractories & Met Wuhan 430081 Peoples R China

Application of waste biomass resources in heavy metal adsorption and new energy development is of great significance to improving environmental pollution and the adjustment of energy structure. For this purpose, we designed a simple method for preparing porous Mo2c/c composite materials based on resource-rich biomass carbon (derived from waste pine wood) and ammonium molybdate, and successfully applied it to the above field. The effects of holding time and sintering temperature on the phase compositions and morphological structures of samples were investigated, and the heavy adsorption capacity (cr(III)) and hydrogen evolution reaction of composite materials were also studied. The results showed that porous biomass Mo2c/c composite materials had significantly higher oxidation resistance, and more prominent pore structure as compared to the pretreated biomass carbon. In addition, porous biomass Mo2c/c composite materials showed excellent adsorption performance for heavy metal cr(III) and catalytic hydrogen evolution reaction performance, its adsorption capacity and Tafel slope were 43.2 mg/g and 123.9 mV/dec, respectively.

关键词： Porous biomass Mo (2) c c Biomass carbon Heavy metal adsorption Hydrogen evolution reaction cr(III)

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