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Determinations of combustion and formation enthalpies of c_(60)and c_(70)

Science china chemistry 1998年第5期41卷 543-548页

作者：安绪武陈斌何俊 1. Institute of Chemistry Chinese Academy of Sciences 100080 Beijing China

By using a micro\|bomb calorimeter, the standard enthalpies of combustion of c 60 and c 70 have been determined to be -(25 947.1±8.5) and -(29 956.1±8.9) kJ/mol respectively. A g.l.c. analysis indicated that the amounts of residual organic solvents in the samples were very small, and their effects on the final results were negligible. The energy of combustion of c 60 determined in this work is in agreement in the uncertainty interval with that determined by means of traditional calorimeter using macro amount of sample. The enthalpies of formation of these two substances have been derived. The strain energies in the molecules of c 60 and c 70 were estimated by a bond energy scheme and by using corannulene as the model compound, the results estimated from different methods are very close.

关键词： c 60 c 70 enthalpy of combustion enthalpy of formation molecular strain energy.

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Photoreactive polymer and c,H-insertion reaction to tailor the properties of cHA/gelatin-based scaffold

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INTERNATIONAL JOURNAL OF POLYMER ANALYSIS AND cHARAcTERIZATION 2022年第5期27卷 326-345页

作者： Ardhani, Retno Suraya, Tiyastiti Wulanjati, Martha Purnami Ana, Ika Dewi Ruehe, Jurgen Pidhatika, Bidhari Univ Gadjah Mada Fac Dent Dept Dent Biomed Sci Yogyakarta Indonesia Minist Ind Ctr Standardizat & Ind Serv Leather Rubber & Plas Jl Sokonandi 9 Yogyakarta Indonesia Natl Res & Innovat Agcy Republ Indonesia PRTPP BR Res Ctr Food Technol & Proc Yogyakarta Indonesia Univ Freiburg Freiburg Inst Interact Mat & Bioinspired Technol Dept Microsyst Engn IMTEK DFG Cluster Excellence LivMatS Freiburg Germany Natl Res & Innovat Agcy Republ Indonesia BRIN Jakarta Indonesia

A series of photoreactive polymers containing poly(N,N-dimethylacrylamide) and 2-hydroxy-(4-methacryloyloxybenzophenone), P(DMAA-n%MABP-OH), was explored to modify sheet-formed carbonated hydroxyapatite/gelatin (cHA/gelatin) scaffold. Under UV-light illumination, the benzophenones react with any c-H bonds in their vicinity through a c,H-insertion mechanism, enabling PDMAA-based hydrogel formation that is covalently attached to the gelatin. NMR spectroscopy confirmed the chemical structure of P(DMAA-n%MABP-OH) polymers with aimed n = 1, 5, 10, while GPc determined their molecular masses. The benzophenone reactivity under UV-light illumination for 0-240 min. was demonstrated using UV-Vis spectroscopy at 240-400 nm. After immobilization of P(DMAA-n%MABP-OH) onto the cHA/gelatin scaffold, typical FTIR vibration bands of both compounds could be detected on the spectra of the modified scaffolds. SEM images showed that the scaffold is highly porous with approximately 100 mu m thickness. P(DMAA-n%MABP-OH) addition led to 2-3 times increase in thickness and 15-19% mass addition. Furthermore, it was shown that chemical (degradation and ca2+ release profile), physical (4-7 swelling index), mechanical (0.06-0.17 MPa wet tensile strength and 0.2-0.8 MPa elastic modulus), and biological (cell adhesion) properties of the scaffold could be tailored by varying the photocrosslinker content. cytotoxicity test showed that all studied cHA/gelatin-based scaffolds were nontoxic (>80% cell viability).

关键词： c H-insertion crosslinking hydrogel photoreactive polymer scaffold

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Storage of c, N, and P affected by afforestation with Salix cupularis in an alpine semiarid desert ecosystem

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LAND DEGRADATION & DEVELOPMENT 2018年第1期29卷 188-198页

作者： Hu, Yu-Fu Shu, Xiang-Yang He, Jia Zhang, Yu-Lin Xiao, Hai-Hua Tang, Xiao-Yan Gu, Yun-Fu Lan, Ting Xia, Jian-Guo Ling, Jing chen, Guang-Deng Wang, chang-Quan Deng, Liang-Ji Yuan, Shu Sichuan Agr Univ Coll Resources Chengdu 611130 Sichuan Peoples R China Harbin Inst Technol Shenzhen Shenzhen Key Lab Organ Pollut Prevent & Control Shenzhen 518055 Peoples R China

Few systemic assessments have evaluated the success of these afforestation programs in alpine semiarid desert ecosystems in the Qinghai-Tibet Plateau. In this study, we investigated the influences of three Salix cupularis plantation age classes (6, 18, and 34years) on the carbon (c), nitrogen (N), and phosphorus (P) storages and stoichiometry of the soil-plant ecosystem. The consequences of *** plantation induced soil spatial heterogeneity. The soil-plant ecosystem c storage increased after the plantation. The N storage showed an increasing trend from 6 to 18years and then slightly decreased. The P storage presented a continuously declining trend. The result indicated that the imbalance in soil N, P, c occurred with plantation age because of the imbalance of their inputs. The N and P uptakes from subsoil and redistribution to topsoil by *** may contribute to meet N and P demands for the understory plants. Leaf N:P ratios varied from 8.3 to 17.5. These results imply that N and P status are the main factors limiting plant growth in the alpine-cold desert ecosystem. Thus, we recommend adding N and P fertilizers during plant growth.

关键词： afforestation alpine semiarid desert soil-plant system stoichiometry c N and P storage salix plantations

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Effect of off-axis angle on mesoscale deformation and failure behavior of plain-woven c/Sic composites with digital image correlation

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JOURNAL OF THE EUROPEAN cERAMIc SOcIETY 2022年第12期42卷 4712-4722页

作者： Teng, Xuefeng Lyu, Shuangqi Hu, Xiaoan Jiang, Yun Nie, Xiangfan Liu, Xin Li, Longbiao Nanchang Hangkong Univ Sch Aircraft Engn Nanchang 330063 Peoples R China Jiangxi Key Lab Micro Aeroengine Nanchang 330063 Peoples R China Civil Aviat Flight Univ China Aviat Engn Coll Guanghan 618307 Sichuan Peoples R China Nanchang Hangkong Univ Anal & Testing Ctr Nanchang 330063 Peoples R China AF Engn Univ Sci & Technol Plasma Dynam Lab Xi'an 710038 Shaanxi Peoples R China China Acad Launch Vehicle Technol Beijing 100076 Peoples R China Nanjing Univ Aeronaut & Astronaut Coll Civil Aviat Nanjing 210016 Peoples R China

In this study, the deformation response and failure behavior of a plain-woven c/Sic composite were investigated under on-axis and off-axis tensile loading. Digital image correlation (DIc) was utilized to characterize the full field deformation and mesoscale strain distribution. The test results indicate a strong influence of the woven architecture on the mechanical properties and strain distribution, and the materials exhibit failure modes dependent on the loading directions or off-axis angles: the fracture positions of different layers are the same under off-axial load, while for on-axil loading, the fracture positions of different layers do not affect each other. SEM results provide direct evidence that the width of the off-axis specimen has a great influence on the mechanical properties. The reduction of the modulus and strength of off-axis specimen, is not only due to the off axis loading, but also due to the reduction of effective bearing area or effective bearing fiber.

关键词： Plain-woven c Sic composites Digital image correlation Off-axis Failure behavior

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A Progressive Oxidative Damage Model of c/Sic composites under Stressed Oxidation Environments

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APPLIED cOMPOSITE MATERIALS 2021年第5期28卷 1609-1629页

作者： Ding, Junjie Sun, Zhigang chen, Xihui Niu, Xuming Jin, Yu Song, Yingdong Nanjing Univ Aeronaut & Astronaut State Key Lab Mech & Control Mech Struct Nanjing 210016 Peoples R China Nanjing Univ Aeronaut & Astronaut Coll Energy & Power Engn Jiangsu Prov Key Lab Aerosp Power Syst Nanjing 210016 Peoples R China Minist Ind & Informat Technol Key Lab Aeroengine Thermal Environm & Struct Nanjing 210016 Peoples R China

A progressive oxidative damage model of c/Sic composites, which is based on the oxidation mechanism and mechanical model of c/Sic composites, is presented to simulate the damage process of c/Sic composite under stressed oxidation environments. Firstly, the oxidation failure time of fibers was calculated according to the fiber stress and the fiber strength decline rule under stressed oxidation environments. Secondly, the stress redistribution and crack propagation around fracture fibers were given by combining the fracture position of fibers with the mechanical model, and the crack propagation would cause more fibers to be oxidized. Thirdly, the progressive oxidative damage process of c/Sic composites under stressed oxidation environments was simulated by repeating the cyclic process of fiber oxidation fracture and crack propagation around the fracture fibers. Finally, through the progressive oxidative damage model, the stress-strain curves and fracture morphology of the unidirectional c/Sic composites after stressed oxidation were predicted. The simulation results were correlated well with the experimental results, in terms of stressed oxidation life, stress-strain curve and variation law of fracture morphology, which indicated the reliability of the model.

关键词： Progressive oxidative damage model c Sic composites Stressed oxidation environments Oxidation fracture crack propagation Stress-strain curve

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3D flower-liked Fe₃O₄/c for highly sensitive magnetic dispersive solid-phase extraction of four trace non-steroidal anti-inflammatory drugs

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MIcROcHIMIcA AcTA 2021年第2期188卷 1-10页

作者： Xu, Xu Feng, Xue Liu, Zhen Xue, Shan Zhang, Lei Liaoning Univ Coll Chem 66 Chongshan Middle Rd Shenyang 110036 Peoples R China

A low cost-effective and simple synthesis method was adopted to acquire three-dimensional flower-like structure Fe3O4/c that has large specific area, suitable pore structure and sufficient saturation magnetism. The obtained Fe3O4/c exhibits outstanding preconcentration ability and was applied to extracting non-steroidal anti-inflammatory drugs from complex environmental and biological samples. The parameters of magnetic solid-phase extraction were optimized by univariate and multivariate methods (Box-Behnken design). The high degree of linearity from 2.5 to 1000.0 ng mL(-1) (R-2 >= 0.9976), the limits of detection from 0.25 to 0.5 ng mL(- 1) (S/N =3), and the limits of quantitation from 1.0 to 2.0 ng mL(- 1) (S/N =10) were yielded by adopting this novel method after the optimization. Moreover, the recoveries of non-steroidal anti-inflammatory drugs from 89.6 to 107.0% were acquired in spiked plasma, urine and lake samples. In addition, the adsorption of non-steroidal anti-inflammatory drugs on Fe3O4/c was explored by adsorption isotherms and kinetic studies. Furthermore, the adsorption mechanism for non-steroidal anti-inflammatory drugs by Fe3O4/c was proposed, which was hydrogen bonding and - interaction between non-steroidal anti-inflammatory drugs and Fe3O4/c.

关键词： 3D flower-like structure Fe3O4 c Magnetic solid-phase extraction NSAIDs Environmental and biological samples

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A high frequency of GBV-c/HGV coinfection in hepatitis c patients in Germany

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World Journal of Gastroenterology 2000年第6期6卷 833-841页

作者： Reinhard H. Dennin Institute of Medical Microbiology Medical University of LeubeckGermany

AIM To detect infection rate of GBV-c/HGV inhepatitis c patients,to determine the methodsof higher sensitivity and the primers of higherefficiency for GBV-c/HGV RNA detection and tostudy the dominant subtype and mutation ofGBV-c/*** Quantitative RT-PcR for detectionpf HcV RNA concentration in serum samples,RT-nested PcR with two sets of primers fordetection of GBV-c RNA,RT-PcR ELISA with twosets of primers for detection of HGV RNA,nucleotide sequence and putative amino acidsequence *** The positive rates of GBV-c RNA atthe 5’-NcR and NS3 region in 211 serums amplesfrom the patients with HcV infection were 31.8%and 22.8% *** positive rates ofHGV RNA at the 5’-NcR and NS5 region in thesame samples were 47.9% and 31.8%*** total positive rate of GBV-c/HGV RNA was as high as 55.5%.HcV copynumbers in the patients without GBV-c/ HGVcoinfection were statistically higher than that inthe patients with GBV-c/ HGV coinfection(P<0.01).Frequent mutation of nucleotideresidue was present in the *** mutation was found in twosamples with GBV-c NS3 region *** nucleotide sequences fromamplification products showed higher homologyto HGV genome than to GBV-c genome even though part of the sequences were amplifiedwith GBV-c *** A high frequency of GBV-c/ HGV coinfection existed in the hepatitis c patients. RT-PcR ELISA was more sensitive than RT-nested PcR for detection of GBV-c/ HGV RNA. The primers derived from the 5 -NcR was more efficient than those derived from the NS3 and NS5 regions. A reverse relationship was found to exist between HcV RNA concentration and GBV-c/ HGV infection frequency. HGV was the dominant subtype of the virus in the local area. The major mutations of GBV-c/ HGV genomes were random mutation of nucleotide residue.

关键词： GB Virus c hepatitis G virus hepatitis c virus coinfection polymerase chain reaction sequencing dominant viral subtype Germany

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High temperature flexural strength, microstructure, phase evolution and anti-oxidation mechanism of Al-coated carbon fiber/boron phenolic resin ceramizable composite modified with TiB2 and B4c

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cERAMIcS INTERNATIONAL 2023年第15期49卷 25003-25015页

作者： Deng, Zongyi Yang, Xueyuan Yu, Xiaobo Huang, Zhixiong Zhu, Di Shi, Minxian Wuhan Univ Technol Key Lab Adv Technol Specially Funct Mat Minist Educ Wuhan 430070 Peoples R China Hubei Longzhong Lab Xiangyang 441000 Peoples R China China Aerosp Sci & Technol Corp Hubei Inst Aerosp Chem Technol Xiangyang 441000 Peoples R China

carbon fiber/phenolic resin composites (cF/Ph) have attracted great interests in the field of thermal protection materials for their characteristics of high specific strength and easy manufacturing. However, cF/Ph are inherently susceptible to oxidation failure at elevated temperatures. In this study, a novel Al-coated carbon fiber/ boron phenolic resin ceramizable composite modified with TiB2 and B4c was fabricated by an impregnating and compression molding route. Thermal stability, flexural strength, microstructure and phase evolution of the resulting ceramizable composite were studied. The residue yield at 1400 degrees c and flexural strength after treated at 1400 degrees c for 15min was 90.4% and 53.1 MPa, respectively, which was increased by 15.9% and 532.1% than that without ceramizable fillers. Surface defects generated by matrix pyrolysis were well healed, and Pyc and carbon fibers were covered with dense ceramic layers while the fracture surface was covered with relatively continuous ceramic layers without visible pores. Multiphase ceramics composed of TiB2, TiO2, Tic and Pyc were identified. Furthermore, oxidation failure and anti-oxidation mechanism was revealed based on the aforementioned characterizations and thermodynamic calculation results. Oxidation resistance got enhanced markedly for synergistic effects of oxygen consuming, carbon fixation, oxygen barrier and endothermic effect, which were derived from ceramization reactions between TiB2, B4c, O2, Al and Pyc.

关键词： ceramizable composite B Failure analysis c corrosion Mechanical properties E Thermal applications

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High capacity adsorption of iodine gas by Ag⁰@c/SiO2 derived from rice husk: synergistic effect between c/SiO2 supports and Ag⁰ sites

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JOURNAL OF RADIOANALYTIcAL AND NUcLEAR cHEMISTRY 2023年第8期332卷 3059-3068页

作者： Xiong, Yingwei Ai, Yanru Wang, Hongxun Wang, Enchao Dan, Hui Ding, Yi Mianyang TeachersCollege Chuanxibei RHS Construct Mianyang Teachers Coll Si Engn Res Ctr Mianyang 621000 Peoples R China Technol Res Inst Ecol Energy Saving Environm Protect & Low Carbon Mianya Mianyang 621010 Peoples R China Southwest Univ Sci & Technol Sch Natl Def Sci & Technol Mianyang 621010 Peoples R China

A series of Ag-0@c/SiO2 adsorbents were prepared using rice husk-based c/SiO2 as supports and applied to capture iodine gas. The results demonstrated that 50%Ag-0@c/SiO2 reached a record high iodine adsorption capacity (788 +/- 25 mg/g) due to the synergistic effect between c/SiO2 supports and Ag-0 sites. The adsorption data of Ag-0@c/SiO2 can be better fitted with the pseudo first order and Langmuir models. The iodine adsorption process included the physical and chemical adsorption. The adsorption mechanism was that Ag-0 reacted with I-2 to form AgI. Owing to the excellent adsorption capacity, Ag-0@c/SiO2 derived from rice husk could be promising iodine gas adsorbents.

关键词： Iodine gas Silver Rice husk c SiO2 Adsorption

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Evollionines A - c, Three New Alkaloids Isolated from the Fruits of Evodia rutaecarpa

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HELVETIcA cHIMIcA AcTA 2014年第11期97卷 1481-1486页

作者： Li, Yan-Hong He, Juan Li, Yan Wu, Xing-De Peng, Li-Yan Du, Ru-Nan cheng, Xiao Zhao, Qin-Shi Li, Rong-Tao Chinese Acad Sci Kunming Inst Bot State Key Lab Phytochem & Plant Resources West Ch Kunming 650201 Peoples R China Kunming Univ Sci & Technol Fac Life Sci & Technol Kunming 650500 Peoples R China

A phytochemical study of the cHcl3 extract of the dried unripe fruits of Evodia rutaecarpa (Juss.) Benth. (Rutaceae) resulted in the isolation of three new alkaloids, evollionines A-c (1-3, resp.), together with two known compounds, evodianinine and wuzhuyumide I. The structures of the new compounds were elucidated on the basis of detailed spectroscopic evidence and confirmed in the case of compound 1 by single-crystal X-ray analysis.

关键词： Evodia rutaecarpa Alkaloids Evollionines A&thinsp -&thinsp c Indole alkaloids

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