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Effects of Mo promoters on the Cu-Fe bimetal catalysts for the DMC formation from CO_2 and methanol

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Chinese Chemical Letters 2013年第4期24卷 307-310页

作者： Ying-Jie Zhou Min Xiao Shuan-Jin Wang Dong-Mei Han Yi-Xin Lu Yue-zhong meng The Key Laboratory of Low-carbon Chemistry & Energy Conservation of Guangdong Province/State Key Laboratory of Optoelectronic Materials and Technologies Sun Yat-sen University Department of Chemistry & Medicinal Chemistry Program Office of Life SciencesNational University of Singapore

The Mo-promoted Cu-Fe bimetal catalysts were prepared and used for the formation of dimethyl carbonate （DMC） from CO2 and methanol. The catalysts were characterized by X-ray diffraction （XRD）, temperature programmed reduction （TPR）, laser Raman spectra （LRS）, energy dispersive spectroscopy （EDS） and temperature programmed desorption （TPD） techniques. The experimental results demonstrated that the Mo promoters can decrease the reducibility and increase the dispersion of Cu-Fe clusters, The concentration balance of base-acid sites can be readily adjusted by changing the Mo content. The moderate concentration balance of acid and base sites was in favor of the DMC formation, Under optimal experimental conditions, the highest methanol conversion of 6,99% with a DMC selectivity of 87.7% can be obtained when 2.5 wt% of Mo was loaded.

关键词： Dimethyl carbonateCarbon dioxideCatalysisBimetal catalyst

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煤矸石对低灰熔点煤灰熔融特性的影响

菏泽学院学报 2024年第2期46卷 18-24页

作者：徐美玲钟梦洁李风海樊红莉菏泽学院化学化工学院山东菏泽274015

煤的灰熔融特性是评价用煤洁净有效转化的重要指数,直接影响煤的气化.主要通过添加煤矸石(CG)的方式,改变两种低灰熔点煤润北煤(RBC)和俄矿煤(EKC)的硅铝比(SiO_(2)/Al_(2)O_(3)),进而探索影响低灰熔点煤灰熔融特性的原理.通过灰熔点测... 详细信息

煤的灰熔融特性是评价用煤洁净有效转化的重要指数,直接影响煤的气化.主要通过添加煤矸石(CG)的方式,改变两种低灰熔点煤润北煤(RBC)和俄矿煤(EKC)的硅铝比(SiO_(2)/Al_(2)O_(3)),进而探索影响低灰熔点煤灰熔融特性的原理.通过灰熔点测定仪的测试结果和FactSage热力学软件的计算结果分析发现,随着CG灰(CGA)含量的增多,低灰熔点煤RBC和EKC的灰熔点逐渐升高.由于CGA与RBC灰混合后,在高温条件下会产生较多含量的SiO_(2)和Al_(2)O_(3),因此,RBC的灰熔融温度随硅铝比S/A的降低而增加,S/A值达到1.83时RBC的灰熔点升为1381℃.而EKC灰中添加CGA后在高温条件下发生反应生成高熔点的白榴石和钾霞石,故EKC的灰熔点也随着S/A的降低而增加,当S/A为1.80时,EKC的灰熔点达到1376℃.

关键词：煤矸石润北煤俄矿煤灰熔融特性 Factsage

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阀门线密封结构的密封性能分析

阀门 2024年第4期 448-453页

作者：刘纯杜兰君钟梦妮李罗金胡树文北京航天动力研究所北京100076

针对阀门中刀型密封结构,采用理论分析和仿真模拟对其密封过程进行研究,主要分析了密封力、阀座刀型角、密封面直径以及材料物理性能对刀型密封结构的密封比压的影响。结果表明:密封力、阀座刀型角、阀座密封面直径以及阀座的杨氏模量... 详细信息

针对阀门中刀型密封结构,采用理论分析和仿真模拟对其密封过程进行研究,主要分析了密封力、阀座刀型角、密封面直径以及材料物理性能对刀型密封结构的密封比压的影响。结果表明:密封力、阀座刀型角、阀座密封面直径以及阀座的杨氏模量对刀型密封结构的密封比压影响较大。基于此,提出了刀型密封结构的密封比压模型,为阀门刀型密封结构设计奠定一定的基础。

关键词：阀门刀型密封密封比压影响因素

Architecting Branch Structure in Terpolymer of CO_(2),Propylene Oxide and Phthalic Anhydride:An Enhancement in Thermal and Mechanical Performances

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Chinese Journal of Polymer Science 2022年第5期40卷 462-468页

作者： Wen-Jing Wang Shu-Xian Ye Jia-Xin Liang Cong-Xiao Fan Yong-Lan Zhu Shuan-Jin Wang Min Xiao Yue-zhong meng The key laboratory of Low-carbon Chemistry&Energy Conservation of Guangdong Province State Key Laboratory of Optoelectronic Materials and TechnologiesSchool of Materials Science and EngineeringSun Yat-sen UniversityGuangzhou 510275China

Poly(propylene carbonate phthalate)(PPC-P)is a chemically modified poly(propylene carbonate)(PPC)biodegradable thermoplastic by introducing phthalic anhydride(PA)as the third monomer into the copolymerization of propylene oxide(PO)and CO_(2).To enhance the thermal and mechanical properties of PPC-P,a branching agent pyromellitic anhydride(PMDA)was introduced into the terpolymerization of PO,PA and CO_(2).The resulting copolymers with branched structure,named branched PPC-P,can be obtained using metal-free Lewis pair consisting of triethyl borane(TEB)and bis(triphenylphosphine)iminium chloride(PPNCl)as *** products obtained were analyzed by NMR spectroscopy and their thermal,mechanical properties and melt processability were evaluated by DSC,TGA,tensile test and melt flow index(MFI)*** obtained branched PPC-P has a high molecular weight up to 156.0 kg·mol^(-1).It shows an increased glass transition temperature(Tg)higher than 50℃and an enhanced tensile strength as high as 38.9 ***,the MFI value decreases obviously,indicative of an improved melt strength arising from the branched structure and high molecular *** is more,the branched PPC-P exhibits reasonable biodegradability,which demonstrates the great potential as a new green thermoplastic for the family of biodegradable plastics.

关键词： CO_(2)utilization Pyromellitic anhydride Biodegradability Branched structure Melt flow index

A novel(Sm0.2Eu0.2Gd0.2Ho0.2Yb0.2)CrO3 high-entropy ceramic nanofiber as a negative temperature coefficient thermistor

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Journal of Rare Earths 2024年第10期42卷 1937-1942页

作者： Weijun Zhao meng Zhang Liyan Xue Kaixian Wang Fan Yang Jiuping zhong Heng Chen School of Materials Sun Yat-sen University Xiamen Institute of Rare Earth Materials Haixi InstituteChinese Academy of Sciences Xiamen Key Laboratory of Rare Earth Photoelectric Functional Materials Xiamen Institute of Rare Earth MaterialsHaixi InstituteChinese Academy of Sciences Fujian Science & Technology Innovation Laboratory for Optoelectronic Information of China Advanced Energy Science and Technology Guangdong Laboratory Sichuan Jcc Rare Earth Metals New Material Co. Ltd.

The electrical properties of high-entropy ceramics（HECs） have been extensively studied in recent years due to their unique structural characteristics and fascinating functional properties induced by entropy *** high-entropy(Sm0.2Eu0.2Gd0.2Ho0.2Yb0.2)CrO3（HE-RECrO3） nanofibers were prepared by electro *** work demonstrates that HE-RECrO3nanofibe rs were successfully synthesized at a low temperature（800℃）,which is approximately 400 ℃ lower than the temperatures at which chromate ceramics were synthesized via the sol-gel method and the solid-state reaction *** resistivity of HE-RECrO3nanofibers decreases exponentially with increasing temperature from 25 to600℃.The logarithm of the resistivity is linearly related to the inverse of the temperature,confirming the negative temperature coefficient property of *** B25/50value of the HERECrO3nanofibers reaches 4072 *** conclusion,HE-RECrO3nanofibers are expected to be potential candidates for negative-temperature-coefficient（NTC） thermistors.

关键词： Ceramic fiber materials High-entropy ceramics Negative temperature coefficient thermistors Rare earths

Chiral multiple-resonance thermally activated delayed fluorescence materials based on chiral spiro-axis skeleton for efficient circularly polarized electroluminescence

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Science China Chemistry 2024年第7期67卷 2257-2264页

作者： Shi-Quan Song Xiao Han zhong-zhong Huo Ching-Fai Yip Xian-Fang Hong meng-Ning Ding You-Xuan Zheng State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic MaterialsSchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China Key Laboratory of Mesoscopic Chemistry of Ministry of Education School of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China

Chiral luminescence materials have potential applications in the field of three-dimensional displays due to their circularly polarized luminescence(CPL)***,the further development of circularly polarized organic light-emitting diodes(CP-OLEDs)needs to meet the requirements of high efficiency,high color purity,low cost,and high dissymmetry factor(gPLor gEL),chiral multiple resonance thermally activated delayed fluorescence(MR-TADF)materials are considered as candidates in these ***,based on a pair of chiral spirofluorene precursors,two pairs of high-performance chiral MR-TADF emitters((R/S)-p-Spiro-DtBuCzB and(R/S)-m-Spiro-DtBuCzB)are developed,which exhibit strong emissions peaking at 491 and 502 nm in toluene with full-width at half-maximum values of 25 and 33 nm,*** addition,small singlet–triplet energy gaps of 0.15 and 0.10 eV with high absolute photoluminescence efficiencies of 95.0%and 96.7%are observed for p-Spiro-DtBuCzB and m-Spiro-DtBuCzB molecules,*** based on p-Spiro-DtBuCzB and m-Spiro-DtBuCzB display high maximum external quantum efficiencies of 29.6%and 33.8%,*** importantly,CP-OLEDs present symmetric circularly polarized electroluminescence spectra with|gEL|factors of 3.36×10^(-4)and 7.66×10^(-4)for devices based on(R/S)-p-Spiro-DtBuCzB and(R/S)-m-Spiro-DtBuCzB enantiomers,respectively.

关键词： chiral spiro-axis skeleton-based material multiple resonance thermally activated delayed fluorescence circularly polarized electroluminescence dissymmetry factor external quantum efficiency

Identifying Three New AGNs among Fermi Unidentified Gigaelectronvolt Sources

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Research in Astronomy and Astrophysics 2024年第7期24卷 257-267页

作者： Shun-Hao Ji zhong-Xiang Wang Qiang-meng Huang Ruo-Heng Yang Department of Astronomy School of Physics and AstronomyYunnan UniversityKunming 650091China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China

We report our identification of three gigaelectronvoltγ-ray sources,4FGL J0502.6+0036,4FGL J1055.9+6507,and 4FGL J1708.2+5519,as Active Galactic Nuclei(AGNs).They are listed in the latest Fermi-Large Area Telescope source catalog as unidentified *** find that the sources all showedγ-ray flux variations in recent *** different survey catalogs,we are able to find a radio source within the error circle of each source's *** analysis of optical sources in the fields allows us to determine the optical counterparts,which showed similar variation patterns to those seen inγ-*** optical counterparts have reported redshifts of 0.6,1.5,and 2.3,respectively,estimated from photometric *** addition,we also obtain an X-ray spectrum of 4FGL J0502.6+0036 and a flux upper limit on the X-ray emission of 4FGL J1055.9+6507 by analyzing the archival *** broadband spectral energy distributions of the three sources from radio toγ-rays are *** mainly theγ-ray properties of the three sources with those of different sub-classes of AGNs,we tentatively identify them as *** optical spectroscopy is highly warranted for obtaining their spectral features and thus verifying the identification.

关键词： gamma-rays galaxies-(galaxies)BL Lacertae objects general-(galaxies)quasars general

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温度对阀门密封比压的影响分析

阀门 2024年第7期 884-887页

作者：刘纯胡树文钟梦妮杜兰君李罗金北京航天动力研究所北京100076

通过仿真研究了不同温度下阀门阀座密封比压的特性,分析不同热膨胀系数对密封比压的影响。结果表明:随着温度的降低,阀门阀座密封比压会稍微增加。此外,在一定范围内,阀芯材料热膨胀系数的变化对密封比压的影响不大,几乎可以忽略。当阀... 详细信息

通过仿真研究了不同温度下阀门阀座密封比压的特性,分析不同热膨胀系数对密封比压的影响。结果表明:随着温度的降低,阀门阀座密封比压会稍微增加。此外,在一定范围内,阀芯材料热膨胀系数的变化对密封比压的影响不大,几乎可以忽略。当阀座的热膨胀系数小于1E-5 K^(-1)时,阀座热膨胀系数变化对密封比压的影响不大,随着温度的降低密封比压几乎不变;当阀座材料的热膨胀系数大于1E-5 K^(-1)时,在低温下阀门的密封比压随着阀座热膨胀系数的增大而增大,这为低温阀门选择阀芯和阀座材料提供一定的参考。

关键词：阀门密封比压温度热膨胀系数

2016-2020年济南市市售苹果中多种农药残留的污染状况及膳食暴露风险评估

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预防医学论坛 2024年第3期30卷 184-190页

作者：曹小丽杨晓倩孟中华王相际刘岚铮济南市疾病预防控制中心理化检验所山东济南250021

目的了解2016-2020年济南市市售苹果中的农药残留状况,并对济南市市售苹果中农药残留开展慢性、急性和累积膳食暴露风险评估。方法2016-2020年采集济南市市售苹果样品225份,筛查和检测有机磷农药、氨基甲酸酯农药、拟除虫菊酯类农药、... 详细信息

目的了解2016-2020年济南市市售苹果中的农药残留状况,并对济南市市售苹果中农药残留开展慢性、急性和累积膳食暴露风险评估。方法2016-2020年采集济南市市售苹果样品225份,筛查和检测有机磷农药、氨基甲酸酯农药、拟除虫菊酯类农药、杀菌剂等共85种,依据GB 2763-2021《食品中农药最大残留限量》对检测结果进行评价。结果共检出18种农药残留,87.6%的苹果样品有一种以上农药残留,多菌灵的检出率最高(为58.7%)。检测到两种或两种以上农药残留的样品约占72.0%。两种禁用农药(久效磷和磷胺)的残留量都超过了各自的最大残留限量值(MRL)。所有年龄段消费人群的急性膳食暴露风险和累积急性膳食暴露风险均超过了可接受的水平。结论济南市市售苹果中农药残留种类较多,慢性膳食暴露风险较小,急性膳食暴露存在一定的健康风险。

关键词：农药残留苹果膳食暴露风险评估