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Effects on the thermal expansion coefficient and dielectric properties of CLST/PTFE filled with modified glass fiber as microwave material

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Chinese Chemical Letters 2019年第5期30卷 1111-1114页

作者： Liu zheng Jing Zhou Jie Shen Yanyuan Qi wen chen State Key Laboratory of Advanced Technology for Materials Synthesis and Processing School of Materials Science and Engineering Wuhan University of Technology

Ceramic and polytetrafluoroethylene composites as dielectric materials have a low dielectric loss at high frequency and play an important role in the modern communication ***,room temperature phase transformation of PTFE resins,which is accompanied by a large volume change(>400 ppm/℃),seriously affects the dimensional stability and performance stability of *** LD125 modified glass fiber(GF)was introduced to the CaO-Li2 O-Sm2O3-TiO2(CLST)/PTFE composite,to reduce the thermal expansion coefficient(CTE)of the *** tri-phase composites(CLST/PTFE/GF)show the low dielectric loss and excellent *** effect of GF content on the dielectric properties and CTE was also *** CLST/PTFE filled with 5%GF exhibits the best overall performance,which is a promising microwave dielectric material for microwave communication.

关键词： Microwave communication Thermal expansion coefficient CLST PTFE Dielectric loss Dielectric constant

On lowest-lying 1/2^(-) octet baryons

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Chinese Physics C 2022年第8期46卷 1-6页

作者： Chang chen wen-Qi Niu Han-Qing zheng Department of Physics and State Key Laboratory of Nuclear Physics and Technology Peking UniversityBeijing 100871China College of Physics Sichuan UniversityChengdu 610065China Collaborative Innovation Center of Quantum Matter Beijing 100871China

The recently proposed N^(*)(890)1/2^(-)baryon is studied in a flavor SU(3) scheme with K-matrix unitarization,by fitting to low-energy cross section and phase shift *** is found that N^(*)(890) co-exists with low-lying poles in other channels,which have been extensively discussed in the literature,though they belong to different octets in the SU(3) ***,the existence of N^(*)(890) is further verified.

关键词： πN scatterings baryon resonance SU(3)octet

The nature of[S Ⅲ]λλ9096,9532 emitters at z=1.34 and 1.23

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Science China(Physics,Mechanics & Astronomy) 2013年第11期56卷 2226-2235页

作者： AN FangXia zheng XianZhong MENG YanZhi chen Yang wen Zhangzheng L GuoLiang School of Physics and Technology Xinjiang University Purple Mountain Observatory China Academy of Sciences Center for Astrophysics University of Science and Technology of China

A study of[S Ⅲ]λλ9096,9532 emitters at z=1.34 and 1.23 is presented using our deep narrow-band H2S 1(centered at 2.13μm)imaging survey of the Extended Chandra Deep Field South(ECDFS).We combine our data with multi-wavelength data of ECDFS to build up spectral energy distributions(SEDs)from the U to the Ks-band for emitter candidates selected with strong excess in H2S 1 Ks and derive photometric redshifts,line luminosities,stellar masses and extinction.A sample of 14[S Ⅲ]emitters are identified with H2S 1<22.8 and Ks<24.8(AB)over 381 arcmin2area,having[S Ⅲ]line luminosity L[S Ⅲ]=~1041.5 42.6erg s *** of the[S Ⅲ]emitters is found to have X-ray counterpart in the deepest Chandra 4 Ms observation,suggesting that they are unlikely powered by *** HST/ACS F606W and HST/WFC3 F160W images show their rest-frame UV and optical *** half of the[S Ⅲ]emitters are mergers and at least one third are disk-type *** all[S Ⅲ]emitters exhibit a prominent Balmer break in their SEDs,indicating the presence of a significant post-starburst *** together,our results imply that both shock heating in post-starburst and photoionization caused by young massive stars are likely to excite strong[S Ⅲ]emission *** conclude that the[S Ⅲ]emitters in our sample are dominated by star-forming galaxies(SFGs)with stellar mass 8.7

关键词： galaxies: evolution galaxies: high-redshift galaxies: emission lines [S Ⅲ]

Gut microbial dysbiosis associates hepatocellular carcinoma via the gut-liver axis

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Hepatobiliary & Pancreatic Diseases International 2019年第1期18卷 19-27页

作者： Jian-wen Jiang Xin-Hua chen Zhigang Ren Shu-Sen zheng Department of Hepatobiliary and Pancreatic Surgery Key Laboratory of Combined Multi-organ Transplantation Ministry of Public Health First Affiliated Hospital Zhejiang University School of Medicine Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases Zhejiang University Health Management Center First Affiliated Hospital Zhejiang University School of Medicine Department of Infectious Disease Precision Medicine Center the First Affiliated Hospital of Zhengzhou University

Background: Hepatocellular carcinoma(HCC) is one of the most common malignancies in the world. Gut microbiota has been demonstrated to play a critical role in liver inflammation, chronic fibrosis, liver cirrhosis, and HCC development through the gut-liver axis. Data sources: Recently there have been several innovative studies investigating gut microbial dysbiosismediated enhancement of HCC through the gut-liver axis. Literatures from January 1998 to January 2018 were searched in the Pub Med database using the keywords "gut microbiota" and "hepatocellular carcinoma" or "liver cancer", and the results of experimental and clinical studies were analyzed. Results: Gut microbial dysbiosis accompanies the progression of alcoholic liver disease, non-alcoholic fatty liver disease and liver cirrhosis, and promotes HCC progression in an experimental mouse model. The immune system and key factors such as Toll-like receptor 4 are involved in the process. There is evidence for gut microbial dysbiosis in hepatitis virus-related HCC patients. Conclusions: Gut microbial dysbiosis is closely associated with hepatic inflammation disease and HCC through the gut-liver axis. With the enhanced understanding of the interactions between gut microbiota and liver through the gut-liver axis, new treatment strategies for HCC are being developed.

关键词： Gut-liver axis Gut microbiota Hepatocellular carcinoma Lipopolysaccharide Toll-like receptor 4

Experimental study on piping in sandy gravel foundations considering effect of overlying clay

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Water Science and Engineering 2016年第2期9卷 165-171页

作者： Shuang Wang Jian-sheng chen Hai-qing He wen-zheng He College of Civil and Transportation Engineering Hohai University College of Earth Sciences and Engineering Hohai University

The influence of the overlying clay on the progression of piping in the sandy gravel foundation of water-retaining structures is often neglected. In order to study this influence, an experimental investigation was conducted on a laboratory-scale model. It was discovered that the critical hydraulic gradient and the area of the piping tunnel increase when the overlying clay thickens. With a thicker clay layer, erosion of the sandy gravel below the clay layer occurs later, but, once the erosion starts, the erosion rate is very high and the average velocity of water seeping through the cross-section of the sandy gravel increases rapidly due to the low deformability of the thick clay layer. Furthermore, it was found that the progression of piping is a complicated and iterative process involving erosion of fine particles, clogging of pores, and flushing of the clogged pores. Two types of erosion have been identified in the progression of piping: one causes the tunnel to advance upstream, and the other increases the depth of the tunnel. The results show that the overlying clay is an important factor when evaluating piping in sandy gravel foundations of water-retaining structures.

关键词： Piping Experimental model Sandy gravel foundation Overlying clay Clog Erosion rate

Selenium-induced Changes in Activities of Antioxidant Enzymes and Content of Photosynthetic Pigments in Spirulina platensis

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Journal of Integrative Plant Biology 2008年第1期50卷 40-48页

作者： Tian-Feng chen wen-Jie zheng Yum-Shing Wong Fang Yang Department of Biology The Chinese University of Hong Kong Hong Kong SAR China Department of Chemistry Jinan University Guangzhou 510632 China

Spirulina platensis exposed to various selenium （Se） concentrations （0, 10, 20, 40, 80, 150, 175, 200, 250 mg/L） accumulated high amounts of Se in a dose- and time-dependent manner. Under low Se concentrations （〈150 mg/L）, Se induced increases in biomass concentration, content of photosynthetic pigments, and activities of glutathione peroxidase （GPX）, superoxide dismutase （SOD）, catalase （CAT） and Gua-dep peroxidases （POD）, which indicates that antioxidant enzymes play an important role in protecting cells from Se stress. Higher Se concentrations （≥175 mg/L） led to higher Se accumulation and increases in activities of GPX, SOD, CAT and POD, but also induced lipid peroxidation （LPO） coupled with potassium leakage and decreases in biomass concentration and contents of photosynthetic pigment. The results indicate that increases in activities of the antioxidant enzymes were not sufficient to protect cell membranes against Se stress. Time-dependent variations in the activities of antioxidant enzymes, contents of chlorophyll a and carotenoid and the LPO level were also investigated under representative Se concentrations of 40 and 200mg/L. Opposite variation trends between SOD-CAT activities, and GPX-POD-APX activities were observed during the growth cycles. The results showed that the prevention of damage to cell membranes of S. platensis cells could be achieved by cooperative effects of SOD-CAT and GPX-POD-APX enzymes. This study concludes that S. platensis possessed tolerance to Se and could protect itself from phytotoxicity induced by Se by altering various metabolic processes.

关键词： accumulation antioxidant enzymes photosynthetic pigments selenium Spirulina platensis.

Formation mechanism of interface reaction layer between microporous magnesia refractories and molten steel and its effect on steel cleanliness

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Journal of Iron and Steel Research International 2023年第9期30卷 1743-1754页

作者： wen-wen Zhang Wan zheng wen Yan Guang-qiang Li The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081HubeiChina Hubei Provincial Key Laboratory for New Process of Ironmaking and Steelmaking Wuhan University of Science and TechnologyWuhan 430081HubeiChina

The ceramic filter in continuous casting tundish can effectively improve the cleanliness of high-performance steel by regulating tundish flow field to promote the removal of inclusions and adsorbing or blocking fine inclusions in the molten steel into the *** interaction between microporous magnesia refractories used as tundish filter and molten interstitial-free(IF)steel at 1873 K was investigated to reveal the formation mechanism of their interface layer and its effect on steel cleanliness by laboratory research and thermodynamic *** results show that the magnesium–aluminum spinel layer at the interface between the molten IF steel and the microporous magnesia refractories is formed mainly by the reaction of MgO in the refractory with the[Al]and[O]in the molten steel,significantly reducing the total O content,the size and amount of inclusions of the molten *** addition,the interparticle phases of microporous magnesia refractories at high temperature can adsorb Al_(2)O_(3) and TiO_(2) inclusions in the molten steel into interparticle channels of the refractories to form high melting point spinel,impeding the further penetration of the molten *** a result,the consecutive interface layer of high melting point spinel between microporous magnesia refractories and molten steel can improve the cleanliness of the molten steel by adsorbing inclusions in the molten steel and avoid the direct dissolution of refractories of the tundish ceramic filter immersed in the molten steel,increasing their service life.

关键词： Tundish metallurgy Microporous magnesia refractory Interstitial-free steel Formation mechanism Interface reaction layer Inclusion removal

Improvement of hydrogen permeation barrier performance by iron sulphide surface films

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International Journal of Minerals,Metallurgy and Materials 2023年第9期30卷 1792-1800页

作者： Pengpeng Bai Shaowei Li Jie cheng Xiangli wen Shuqi zheng Changfeng chen Yu Tian State Key Laboratory of Tribology Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China School of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China School of Mechanical Electronic&Information Engineering China University of Mining and Technology-BeijingBeijing 100083China State Key Laboratory of Heavy Oil Processing China University of PetroleumBeijing 102249China

Fe–S compounds with hexagonal crystal structure are potential hydrogen permeation barrier during H2S corrosion. Hexagonal system Fe–S films were prepared on carbon steel through corrosion and CVD deposition, and the barrier effect of different Fe–S films on hydrogen permeation was tested using electrochemical hydrogen permeation method. After that, the electrical properties of Fe–S compound during phase transformation were measured using thermoelectric measurement system. Results show that the mackinawite has no obvious barrier effect on hydrogen penetration, as a p-type semiconductor, and pyrrhotite (including troilite) has obvious barrier effect on hydrogen penetration,as an n-type semiconductor. Hydrogen permeation tests showed peak permeation performance when the surface was deposited with a continuous film of pyrrhotite (Fe_(1–x)S) and troilite. The FeS compounds suppressed hydrogen permeation by the promotion of the hydrogen evolution reaction, semiconducting inversion from p-to n-type, and the migration of ions at the interface.

关键词： hydrogen permeation barrier iron sulfide pyrrhotite semiconductor

Ceramic-based meta-material absorber with high-temperature stability

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Rare Metals 2024年第9期43卷 4433-4440页

作者： Xing-Cong chen Wei-Jia Luo Run-Ni Zhao Yong-zheng wen Ji Zhou State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China

With the continuous exploration of uncharted and extreme environments,enhanced temperature robustness of passive devices has become particularly *** this study,a ceramic-based meta-material absorber with exceptional temperature stability is developed using a fusion design approach that combines rare metal-based tungsten bronze structural ceramics and ***,the absorbance of the meta-material array based on Mie resonance exceeds 49.0%in both waveguides and free space,approaching the theoretical *** to impedance analysis,the absorption performance can be distinctly correlated with the dielectric loss(Q_(f)).Notably,the high-temperature robustness is verified to still be effective at 400℃.These advancements in our design allow for the use of monolithic materials in fabricating temperature-stable perfect absorbers,providing greater freedom in the dielectric performance and expanding their potential applications,including in space exploration and 5G millimeter-wave scenarios.

关键词： Temperature robustness Meta-material absorber Microwave absorption Rare metal-based ceramics Miniaturization