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A Facile Strategy for Intrinsic Low-Dk and Low-Df Polyimides Enabled by Spirobifluorene Groups

Chinese Journal of Polymer Science 2023年第2期41卷 288-296页

作者： wan-Yi Tan Ling-Feng Jian Wei-Peng Chen Yong-Wen Zhang Xiao-Chuang Lu wan-jun Huang Ji-Sheng Zhang Jing-Wu Wu jun-Li Feng Yi-Dong Liu Ting-Ting Cui Yong-Gang Min Guangdong University of Technology(GDUT) Guangzhou510006China Huimai Materials Technology(Guangdong)Co. Ltd.Foshan528200China Shenzhen Customs Industrial Product Inspection Technology Center Shenzhen518026China

Modified polyimides(MPIs)show great potential towards 5G communication applications,due to its excellent thermal stability,mechanical property and chemical stability as compared to most of *** fluoride groups or porous structure is favorable to ultra-low dielectric constant(D_(k))and dielectric loss(D_(f)).However,the cost of the fluorinated MPIs is high and their synthetic processes are complicated,and porous MPIs suffer poor mechanical ***,increasing the fraction of free volume is a very effective way to lower D_(k)through introducing more ultra-low-D_(k)air ***,most of this kind of MPIs lag far behind the fluorinated MPIs and the porous MPIs in terms of ultra-low D_(f),hindering the application of MPIs in high-speed communication ***,it is highly desirable to develop intrinsic ultra-low-D_(k)/D_(f)MPIs at high frequency with less fluoric groups and nonporous ***,we introduce a facile and effective strategy to lower D_(k)and D_(f)through introducing rigid and large sterically hindered aromatic groups into *** the one hand,their large steric hindrance effect leads to low D_(k)by increasing intrinsic free *** the other hand,the resulting highly stiff polymer chain and strong intermolecular interaction are favorable to reduce D_(f)by inhibiting dipole *** on this strategy,the spirobifluorene groups are *** as-prepared MPIs show excellent dielectric performance with low D_(k)of 2.74–2.76 and low D_(f)of 0.00599 at 10 GHz,to some extent,exceeding the multiple fluorinated MPI with D_(k)/D_(f)of 2.67/0.00663 at 10 GHz.

关键词： Polyimide High speed communication Low dielectric constant Low dielectric loss

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Analytical optimization on GNSS buoy array for underwater positioning

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Acta Oceanologica Sinica 2019年第7期38卷 137-143页

作者： Ke Qi Guoqing Qu Shuqiang Xue Tianhe Xu Xiaoqing Su Yixu Liu jun wan School of Civil and Architectural Engineering Shandong University of TechnologyZibo 255000China Chinese Academy of Surveying and Mapping Beijing 100830China School of Geological and Surveying Engineering Chang’an UniversityXi’an 710054China Institute of Space Sciences Shandong UniversityWeihai 264200China

Global navigation satellite system(GNSS)/acoustic positioning precision is determined by the positioning geometry and the ranging precision;thus optimizing GNSS buoys array is meaningful to improve the positioning accuracy and *** analytical method is proposed for optimizing the GNSS buoys array with regard to the cutoff angle constraints for underwater acoustic *** the practical limitation of coplanarity of GNSS buoys and the cutoff angle,an algorithm is proposed to analytically minimize the position dilution of precision(PDOP).The proposed method is validated to give complete solutions of PDOP minimization with five GNSS *** last,in order to search a best configuration among the PDOP solution set,we propose a search algorithm to get the solution with the smallest geometric dilution of precision(GDOP).It indicates that within a given region,the GDOP minimization at the center of a region is equivalent to the PDOP mean minimization over the *** relation between the positioning accuracy and the positioning geometry with five known points is illustrated in an experiment performed in South China Sea.

关键词： underwater positioning GNSS buoy GDOP optimization

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Industrial Application of Desulfurization Using Low Basicity Refining Slag in Tire Cord Steel

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Journal of Iron and Steel Research International 2013年第1期20卷 26-33页

作者： CHEN Shu-hao wanG Xin-hua HE Xiao-fei wanG wan-jun JIANG Min School of Metallurgical Science and Engineering Central South University School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

Desulfurization performance with low binary basicity refining slag in 72 grade tire cord steel was calculated using FactSage and it is found that sulfur content in steel decreases with the increase of basicity of slag, MgO content in slag and slag/steel ratio while sulfur partition ratio between slag and steel increases gradually with the increase of basicity of slag as well as MgO content. Experiments were carried out and the results are of great agreements with theoretical calculation. Then industrial application tests were performed in a domestic plant and good results were achieved. Sulfur content in steel decreases gradually during refining process, as a result, sulfur content in the billets is controlled in the range of 0.007 1%-0.008 1%. Sulfur content in steel refined with slag basicity of 1.21 is lower than that of 1.02, while the plasticity of oxide compound inclusions is a little better controlled in low basicity heats. Using refining slag with basicity of 1.0-1.2 and MgO content of 5%-10% and reducing the slag takeover of LD are favorable for improving the desulfurization performance and the plasticity of inclusions during the industrial production.

关键词： FactSage desulfurization behavior low basicity refining slag sulfur partition ratio sulfur content

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Cleanliness of Alloying Structural Steel

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Journal of Iron and Steel Research International 2011年第12期18卷 6-11,21页

作者： YU Hui-xiang wanG Xin-hua ZHANG Jing LI Hai-bo wanG wan-jun School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China Research and Development Center Shougang Group Beijing 100043 China

Alloying structural steel used for mechanical structures has a high requirement for cleanliness because its failures are greatly affected by non-metallic inclusions and total oxygen content in *** has been reported by some steelmaking plants to have some problems in controlling total oxygen content and inclusions during alloying structural steel *** this purpose,cleanliness control in 0.2C-0.3Si-0.6Mn-1Cr-0.2Mo steel was ***,low melting temperature zone（≤1873 K） of CaO-Al2O3-MgO system and formation condition of low melting temperature inclusions were investigated through thermodynamic equilibrium *** this basis,industrial tests were carried *** sampling at different stages,transformation of oxide inclusions and change of total oxygen content in steel were *** results show that：in order to form CaO-Al2O3-MgO system inclusions with low melting temperature,mass percent of Al2O3,MgO and CaO in inclusions should be controlled from 37.6% to 70.8%,0 to 17.4% and 25.5% to 60.6%;For the condition of 1873 K and 0.05%（mass percent） dissolved aluminum in steel,the activities of dissolved oxygen,magnesium and calcium should be controlled as 0.298×10-4-2×10-4,0.1×10-5-40×10-5 and 0.8×10-8-180×10-8 *** secondary refining proceeding,average total oxygen content and inclusion amount decrease,the type of most inclusions changes from Al2O3 after tapping to Al2O3-MgO after top slag is formed during ladle furnace refining and finally to CaO-Al2O3-MgO after RH *** the final products,average total oxygen content was 12.7×10-6 and most inclusions were in spherical shape with size less than 5 μm.

关键词： oxide inclusion total oxygen content alloying structural steel thermodynamic calculation secondary refining

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Carbon sequestration of plantation in Beijing-Tianjin sand source areas

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Journal of Mountain Science 2018年第10期15卷 2148-2158页

作者： LIU Xiu-ping ZHANG wan-jun CAO Jian-sheng YANG Bai CAI Yan-jiang Key Laboratory of Agricultural Water Resources Hebei Key Laboratory of Agricultural Water-Saving Center for Agricultural Resources Research Institute of Genetics and Developmental Biology Chinese Academy of Sciences Environmental Sciences Division Oak Ridge National Laboratory Key Laboratory of Mountain Environment Evolvement and Regulation Institute of Mountain Hazards and Environment Chinese Academy of Sciences

The Beijing-Tianjin Sand Source Control Project(BTSSCP), a national ecological restoration project, was launched to construct an ecological protection system in the Beijing-Tianjin sand source areas to reduce dust hazards. The carbon sequestration dynamics can be used to assess the ecological effects of an ecological restoration project. Here, we conducted vegetation and soil study to assess the carbon sequestration in the plantations with 10 years old stands in Beijing-Tianjin sand source areas. The results at the site scales indicated that the average net increase of plantation ecosystem carbon stock was 33.8 Mg C ha^(-1), with an annual increase rate of 3.38 Mg C ha^(-1) yr^(-1). The average net increase of carbon varied among regions, vegetation types, and forest management activities. Soil bulk density in the top soil decreased slightly after 10-year implementation of the project. Coniferous forests and shrubs are suitable plant species for sand source *** restoration in the plantations is a practical and feasible and promising approach for enhancing ecosystem carbon sequestration potential.

关键词： Afforestation Carbon sequestration Carbon density Forest management Restoration Sand source control

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RNA interference-mediated silencing of a Halloween gene spookier affects nymph performance in the small brown planthopper Laodelphax striatellus

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Insect Science 2015年第2期22卷 191-202页

作者： Shuang Jia Pin-jun wan Li-Tao Zhou Li-Li Mu Guo-Qing Li Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests College of Plant Protection Nanjing AgriculturalUniversity Nanjing China

Post-embryonic development of insects is highly dependent on ecdysteroid hormone 20-hydroxyecdysone. Halloween gene spookier （spok, cyp307a2） has been documented to be involved in ecdysteroidogenesis in Drosophila melanogaster and Bombyx mori. We describe here the cloning and characterization of Halloween gene spookier （Lsspok, Lscyp307a2） in the small brown planthopper Laodelphax striatellus, a hemipteran insect species. LsSPOK has three insect-conserved P450 motifs, that is, Helix-K, PERF motif and heme-binding domain. Temporal and spatial expression patterns of Lsspok were evaluated by quantitative polymerase chain reaction. Through the fouth- instar and the early fifth-instar stages, Lsspok showed two expression peaks in the second- and fifth-day fourth-instar nymphs, and two troughs in the first-day fourth and fifth in- stars. On day 5 of the fourth-instar nymphs, Lsspok clearly had a high transcript level in the thorax where prothoracic glands were located. Dietary introduction of double-stranded RNA of Lsspok in the nymph stage successfully knocked down the target gene, decreased expression level ofecdysone receptor （LsEcR） gene, caused nymphal lethality and delayed development. Ingestion of 20-hydroxyecdysone in Lsspok-dsRNA-exposed nymphs did not increase Lsspok expression level, but almost completely rescued the LsEcR mRNA level and relieved the negative effects on survival and development. Thus, our data suggest that the ecdysteroidogenic pathway is conserved in insects and LsSPOK is responsible for specific steps in ecdysteroidogenesis in L. striatellus.

关键词： development double-stranded RNA ecdysteroidogenesis Laodelphaxstriatellus lethality spookier

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Therapeutic effects of Caspase-1 inhibitors on acute lung injury in experimental severe acute pancreatitis

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World Journal of Gastroenterology 2007年第4期13卷 623-627页

作者： Xiao-Hua Zhang Ren-Min Zhu Wen-An Xu Hai-jun wan Heng Lu Department of Gastroenterology Jinling Hospital Nanjing 210002 Jiangsu Province China

AIM： To assess the therapeutic effect of Caspase-1 inhibitors （ICE-I） on acute lung injury （ALI） in experimental severe acute pancreatitis （SAP）. METHODS： Forty-two SD rats were randomly divided into 3 groups： healthy controls （HC, n = 6）; SAP-S group （n = 18）; SAP-ICE-i group （n = 18）. SAP was induced by retrograde infusion of 5% sodium taurocholate into the bile-pancreatic duct. HC rats underwent the same surgical procedures and duct cannulation without sodium taurocholate infusion, in SAP-S group, rats received the first intraperitoneal injection of isotonic saline 2 h after induction of acute pancreatitis and a repeated injection after 12 h. In SAP-ICE-I group, the rats were firstly given ICE inhibitors intraperitoneally 2 h after induction of pancreatitis. As in SAP-S group, the injection was repeated at 12 h. Serum 1L-1β was measured by EUSA. Intrapulmonary expression of Caspase-1, IL-1β and IL-18 mRNA were detected by semi-quantitative RT-PCR. The wet/dry weight ratios and histopathological changes of the lungs were also evaluated. RESULTS： Serum IL-1β levels in SAP-S group were 276.77 ± 44.92 pg/mL at 6 h, 308.99 ± 34.95 pg/mL at 12 h, and 311.60 ± 46.51 pg/mL at 18 h, which were increased significantly （P 〈 0.01, vs HC）. in SAP- ICE-I group, those values were decreased significantly （P 〈 0.01, vs SAP-S）. intrapulmonary expression of Caspase-1, IL-1β and IL-18 mRNA were observed in the HC group, while they were increased significantly in the SAP-S group （P 〈 0.01, vs HC）. The expression of IL-lβ and IL-18 mRNA were decreased significantly in the SAP- ICE-I group （P 〈 0.01, vs SAP-S）, whereas Caspase-1 mRNA expression had no significant difference （P 〉 0.05）. The wet/dry weight ratios of the lungs in the SAP-S group were increased significantly （P 〈 0.05 at 6 h, P 〈 0.01 at 12 h and 18 h, vs HC） and they were decreased significantly in the SAP-ICE-I group （P 〈 0.05, vs SAP-S）.Caspase-1 inhibitors ameliorated the severity of ALl in SAP.CONCLUSION： Caspas

关键词： Severe acute pancreatitis Caspase-1 Interleukin-lβ Interleukin-18 Acute lung injury

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Progress in the sustainable recycling of spent lithium-ion batteries

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SusMat 2021年第2期1卷 241-254页

作者： Min Fan Xin Chang Qinghai Meng Li-jun wan Yu-Guo Guo CAS Key Laboratory of Molecular Nanostructure and Nanotechnology CAS Research/Education Center for Excellence in Molecular SciencesBeijing National Laboratory for Molecular Sciences(BNLMS)Institute of ChemistryChinese Academy of Sciences(CAS)BeijingP.R.China School of Chemical Sciences University of Chinese Academy of SciencesBeijingP.R.China

Lithium-ion batteries(LIBs)are booming in multiple fields due to a rapid devel-opment in the last ***,limited by operational lifespans,a grow-ing number of spent LIBs reaching the end of their lives are consequently faced with serious accumulation and descended to hazardous *** proper disposal,the spent LIBs will inevitably cause negative influence on the ecol-ogy and undermine the sustainable manufacture of *** initial research of recycling strategies mainly focused on the optimization of metallurgical ***,the sustainability of the recycling process has attracted much more attention and become an important ***,we summarize the recent progress of the spent LIBs recycling from a sustainable perspective,especially discussing the green innovations in recycling strategies for spent *** this article,we expect to reveal the challenges and developing tendency of the recycling strategies and provide a guideline for future researches on process-ing spent LIBs and beyond,like the recycling of the solid-state lithium metal batteries.

关键词： applications recycling strategies regeneration solvents spent lithium-ion batteries

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Enhancement of the geomagnetic field reduces the phototaxis of rice brown planthopper Nilaparvata lugens associated with frataxin down-regulation

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Insect Science 2020年第5期27卷 1043-1052页

作者： Ying-Chao Zhang Gui-jun wan Wei-Hong wang Yue Li Yang Yu Yu-Xia Zhang Fa-jun Chen Wei-Dong Pan Beijing Key Laboratory of Bioelectromagnetics Institute of Electrical EngineeringChinese Academy of SciencesBeijingChina University of Chinese Academy of Sciences BeijingChina Department of Entomology College of Plant ProtectionNanjing Agricultural UniversityNanjingChina

The geomagnetic field(GMF)is an environmental cue that provides directional information for *** intensity of GMF is varied over space and *** in the GMF intensity afect the navigation of animals and their *** this study,the phototaxis of the migratory insect rice planthopper Nilaparvata lugens(***)and frataxin in ***(NI-fh),which is a mitochondrial protein required for cellular iron homeostasis and iron-sulfur cluster assembly,were investigated by using different intensities of magnetic *** the results,individuals of *** showed decreased phototaxis when reared and tested in a behavioral arena under a strong magnetic *** the reduction in performance,an accompanying ffect of the strong magnetic field condition was a reduced level of Nl-fh-messenger RNA,and a NI-fh knockdown indeed impaired the phototactic behavior in a tested sample of *** leads to the conclusion that the expression of frataxin is dependent on the strength of the surrounding magnetic field and that functional frataxin facilitates phototactic behavior in ***.

关键词： frataxin ma gnetic field migratory Nilaparvata lugens phototaxis

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Controlled synthesis of hierarchically-structured MnCo_2O_4 and its potential as a high performance anode material

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Science China Chemistry 2017年第9期60卷 1180-1186页

作者： Zixiao Wu Fuhai Li Yonggang Sun Deshan Bin junyu Piao Xijie Lin Xiaochan Liu Anmin Cao Li-jun wan CAS Key Laboratory of Molecular Nanostructure and Nanotechnology and CAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

To satisfy the upsurging demand for energy storage in modern society,anode materials which can deliver high capacity have been intensively researched for the next generation lithium ion ***,the binary MnCo_2O_4 with a characteristic coupled metal cations showed promising potential due to its high theoretical capacity and low ***,by means of a well-designed synthesis control,we demonstrated a scalable process to achieve a hierarchical structure of MnCo_2O_4,which existed as uniform microspheres with embedded mesopores,showing favorable structural characters for high performance during a fast charge/discharge *** synthesis highlighted the importance of sodium salicylate as an essential additive to control the precipitation of the two involved metal *** was proved that a dual role was played sodium salicylate which cannot only facilitate the formation of microspheric shape,but also act as an effective precursor for the creation of inner *** confirmed that the hierarchically-structured MnCo_2O_4 showed outstanding performance when it was tested as an anode material in lithium ion batteries as revealed by its extraordinary cycling stability and high rate capability.

关键词： hierarchical structure anode materials MnCo2O4 lithium ion batteries porous structure

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