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Fabrication of Electrospun PVDF Nanofibers with Higher Content of Polar β Phase and Smaller Diameter by Adding a Small Amount of Dioctadecyl Dimethyl Ammonium Chloride

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Chinese Journal of Polymer Science 2017年第8期35卷 992-1000页

作者： wei xue cong lv yao jing 陈枫傅强 College of Polymer Science and Engineering State Key Laboratory of Polymer Materials Engineering Sichuan University Chengdu 610065 China

In this work,the effect of dioctadecyl dimethyl ammonium chloride（DDAC,a kind of alkyl ammonium salt） on polar β phase content and the diameter of electrospun PVDF nanofibers was investigated for the first *** experimental results show that the diameter of the electrospun PVDF nanofiber could be largely reduced and the content of polar β phase also become dominant immediately by just adding a little amount of *** the mass fraction of DDAC reached 4%,the content of polar β phase increased by about 39.1% compared with PVDF nanofibers without ***,the crystallinity of PVDF nanofibers also increased with the addition of *** on the results,the possible mechanism of cooperative effect between electrospinning and DDAC on fiber diameter and formation of β phase in PVDF was discussed.

关键词： Diameter crystalline crystallinity polar cooperative adding Polar ammonium alkyl attributed

Probing surface interactions of underwater oleophobic polyelectrolyte multilayers

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Petroleum Science 2021年第1期18卷 307-321页

作者： Kai Li wei Wang Zhi-Peng Yu Hang Jin Yun-Tong Ge wei-wei Gao Fan Xiao Hui-Rong Huang Ze-Heng Peng Jing Gong National Engineering Laboratory for Pipeline Safety MOE Key Laboratory of Petroleum EngineeringBeijing Key Laboratory of Urban Oil and Gas Distribution TechnologyChina University of PetroleumBeijing 102249China Key Laboratory of Environmental Protection Technology on Water Transport Tianjin Research Institute for Water Transport EngineeringTianjin 300456China

In the present work,the interaction mechanism of specific polyelectrolyte multilayers(PEMs),fabricated by layer-by-layer deposition of polydiallyldimethylammonium chloride(PDDA)and poly(sodium 4-styrenesulfonate)(PSS),is studied using atomic force *** underwater oil-repellency of PS S-capped PEMs was further explored by measuring the interaction forces between tetradecane droplets and PEMs-coated silica substrates under various *** force curves were analyzed following the Stokes-Reynolds-Young-Laplace theoretical *** consistency was achieved between the experimental and theoretical calculations at low NaCl concentrations(0.1 mM and 1 mM);however,underestimation of the attractive force was found as the NaCl concentration increases to moderate(10 mM)and high(100 mM)*** analyses and incorporated features toward a reduced surface charge density were considered based on the previous findings of the orientation of anionic benzenesulfonate moieties(Liu et *** Angew Chem Int Ed 54(16):4851-4856,***://***/10.1002/anie.201411992).Short-range steric hindrance interactions were further introduced to simulate"brush"effect stemming from nanoscale surface *** is demonstrated in our work that the PSS-capped PEMs remains a stable underwater lipophobicity against high salinity,which renders it potential application in surface wetting modification and anti-fouling.

关键词： Lipophobicity Salinity AFM Polyelectrolyte multilayers Surface roughness

Factors influencing water quality indices in a typical urban river originated with reclaimed water

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Frontiers of Environmental Science & Engineering 2017年第4期11卷 73-82页

作者： Jiao Zhang Zhen wei Haifeng Jia Xia Huang State Key Joint Laboratory of Environment Simulation and Pollution Control School of Environment Tsinghua University Beijing 100084 China

The water quality in a typical urban river segment originated with reclaimed water in Beijing was monitored for two years to investigate the evolution of water quality along the rivcr, and statistical analysis was applied to determine factors influencing water quality of such river recharged by reclaimed water. It was found that no significant change in pollutant concentrations （including COD, NH4＋-N, TN and TP） was observed during this time, and their average values were close to those of the original reclaimed water. However, turbidity and algal contents fluctuated temporally in the direction of river flow. Statistical analysis showed that turbidity was strongly positively correlated with algal contents for flow rate 〈 0.1 m.s-1. whereas it was strongly positively correlated with both algalcontents and TOC for flow rate 〉 0. 1m. s-1. It was observed that diatom was the absolute predominant phyla with Melosira as the major species. In terms of algal bloom control, the specific growth rate of algae was strongly correlated to temperature, and was influenced by flow rate as well. Compared with two other rivers originated with reclaimed water and one originated with natural water, the Shannon Wiener index in the objective river was the lowest, with values between 0.7 and 1.6, indicating a high risk for algal bloom. Statistics showed that Shannon Wiener index was strongly negatively correlated to nutrient salts and cations.

关键词： Reclaimed water Urban river Turbidity Algae Flow rate

Integrated utilization of municipal solid waste incineration fly ash and bottom ash for preparation of foam glass-ceramics

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Rare Metals 2019年第10期38卷 914-921页

作者： Bo Liu Qiang-wei Yang Shen-Gen Zhang Institute for Advanced Materials and Technology University of Science and Technology Beijing

For the purpose of solid waste co-disposal and heavy metal stabilization,foam glass-ceramics were produced by using municipal solid waste incineration(MWSI)bottom ash and fly ash as main raw materials,calcium carbonate(CaCO3) as foamer and sodium phosphate(Na3PO4) as foam *** influences of the raw material composition,foaming temperature and foaming time on the properties were ***,bulk density,mechanical property and leaching of heavy metals were analyzed *** product,foamed at 1150℃ for 30 min with 14% fly ash and 74% bottom ash,exhibits excellent comprehensive properties,such as high porosity(76.03%),low bulk density(0.67 g·cm-3) and high compressive strength(10.56 MPa).Moreover,the amount of leaching heavy metals,including Cr,Pb,Cu,Cd and Ni,in foam glass-ceramics is significantly lower than that of the US EPA hazardous waste *** study not only realizes the integrated utilization of bottom ash and fly ash,but also addresses a new strategy for obtaining foam glass-ceramics.

关键词： Municipal solid waste incineration ash Foamglass-ceramics Mechanical properties Stabilization

Computational Investigation of Blade slotting on a High-Load Low-Pressure Turbine Profile at various Reynolds Numbers:Part Ⅰ——Slotting Scheme's Verification

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Journal of Thermal Science 2011年第1期20卷 13-20页

作者： Qiang Du Junqiang Zhu Min Zhou wei Li Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 Graduate School of Chinese Academy of Sciences Beijing 100190 China Key Laboratory of Advanced Energy and Power Chinese Academy of Sciences （Institute of Engineering Thermophysics） Beijing 100080 China Beijing Aeronautical Technology Research Center Beijing 100076 ER. China

Boundary layer separation and reattachment is often an unavoidable feature of low pressure (LP) turbine,one of the main causes of this phenomenon is the high altitude low Reynolds number experienced by the modern LP turbine stage in *** an excellent turbine airfoil design can avoid flow separation on certain extent,but within flight envelope,LP turbine's characteristic Reynolds number may varied greatly,so it will be still under the risk of the presence of separation *** this two parts paper a new concept of slotted-blade was raised to testify the gain of the blade slotting.A high aerodynamic loading LP turbine blade IET-LPTA was under investigated with different Reynolds *** results reveal that the blade slotting could be a way of choice to suppress separation bubble and reduce profile loss under the condition of low Reynolds number,although its position and geometry need to be further investigated.

关键词： Boundary layer separation and reattachment High aerodynamic loading LP turbine blade Slotted-blade

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Numerical investigation of the cavitation dynamic parameters in a Francis turbine draft tube with columnar vortex rope

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Journal of Hydrodynamics 2019年第5期31卷 931-939页

作者： Jing Yang Ling-jiu Zhou Zheng-wei Wang Technology Center State GridXinyuan Company Ltd.Beijing 100161China Department of Thermal Engineering Tsinghua UniversityBeijing 100084China College of Water Conservancy and Civil Engineering China Agricultural UniversityBeijing 100083China

The cavitation developed in the Francis turbine draft tube is known to be a source of the hydraulic instability,especially under the conditions with columnar cavitation vortex rope occurring in the draft *** hydraulic system will suffer from the risk of the self-excitation and the high pressure pulsations because of the dynamic features of the complex cavitation vortex *** links between the cavitation dynamic characteristics and the hydraulic system stability are important for an accurate system instability *** this purpose,the cavitating flows in a Francis turbine operating under the overload conditions are simulated by using the Zwart-Gerber-Belamri(ZGB)cavitation *** cavitation dynamic parameters in different cavitation development stages and the evolutions under various overload conditions are analyzed and compared in this *** is shown that the cavitation dynamic parameters,including the cavitation compliance,the mass flow gain factor and the wave speed,can well represent the cavitation characteristics with the vortex rope *** predicted cavitation dynamic parameters are in a reasonable agreement with other available results,with an obvious dependency on the *** results obtained in this study are relevant to the system stability analysis.

关键词： Cavitation vortex rope cavitation compliance mass flow gain factor wave speed

Theoretical and Experimental Studies on Low-Temperature Adsorption Drying of Fresh Ginger

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Journal of Thermal Science 2006年第1期15卷 71-78页

作者： Xiaoxi YANG wei XU Jing DING Yi ZHAO The Key Laboratory of Enhanced Heat Transfer and Energy Conservation Ministry of Education South China University of Technology Guangzhou 510640 China Dongguan University of Technology Dongguan Guangdong 523106 China MaoMing College Maoming Guangdong 525000 China

The working principle of low-temperature adsorption drying and the advantages of its application for biological materials drying were introduced in this paper. By using fresh ginger as the drying material, the effects of temperature and relative humidity on its drying characteristics were examined. The results show that the drying rate increases with the temperature increasing or the humidity decreasing. The drying time to the equilibrium is almost the same under different humidity conditions, but low equilibrium moisture content can be acquired under low humidity. The shrinkage characteristics of fresh ginger were also studied. The change of its surface appearance during the drying process was characterized by the new Charged Coupled Device （CCD） and the Environmental Scanning Electron Microscopy （ESEM） technique. A mathematical model of drying dynamics was set up according to the experiments.

关键词： low-temperature adsorption drying ginger drying characteristics shrinkage characteristics mathematical model.

Research progress of disinfection and disinfection by-products in China

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Journal of Environmental Sciences 2019年第7期31卷 52-67页

作者： Xuefeng Sun Miao Chen Dongbin wei Yuguo Du State Key Laboratory of Environmental Chemistry and Eco-Toxicology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences University of Chinese Academy of Sciences

Disinfection is an indispensable water treatment process for killing harmful pathogens and protecting human health. However, the disinfection has caused significant public concern due to the formation of toxic disinfection by-products(DBPs). Lots of studies on disinfection and DBPs have been performed in the world since 1974. Although related studies in China started in1980 s, a great progress has been achieved during the last three decades. Therefore, this review summarized the main achievements on disinfection and DPBs studies in China, which included:(1) the occurrence of DBPs in water of China,(2) the identification and detection methods of DBPs,(3) the formation mechanisms of DBPs during disinfection process,(4) the toxicological effects and epidemiological surveys of DBPs,(5) the control and management countermeasures of DBPs in water disinfection, and(6) the challenges and chances of DBPs studies in future. It is expected that this review would provide useful information and reference for optimizing disinfection process, reducing DBPs formation and protecting human health.

关键词： Disinfection Disinfection by-products Identification Formation mechanisms Toxicology Control

Radiation damage of 1Cr18Ni9Ti and Zr-Ti-Al alloys due to energetic particle irradiation

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Acta Metallurgica Sinica(English Letters) 2012年第1期25卷 29-39页

作者： Maosheng CHAI Wensheng LAI Zhengcao LI wei FENG Department of Materials Science and Engineering Tsinghua UniversityBeijing 100084China

The radiation damage of 1Cr18Ni9Ti stainless steel and the Zr-Ti-Al alloy by 200 keV Xe＋ ions bombardment at the fluence ranging from 1×1014 to 8×1015 ions/cm2 has been investigated by conventional transmission electron microscope, X-ray diffraction line profile analysis （XRDLPA） and nanoindentation. XRDLPA shows that the order of magnitude of dislocation density in both materials remains almost unchanged up to the highest irradiation dose. Selected-area electron diffraction combined with bright and dark field image indicates that 1Cr18Ni9Ti is more easily damaged than the Zr-Ti-Al alloy. With increasing the ions fluence, the radiation damage became more severe in 1Cr18Ni9Ti, accompanied with phase transition and partial amorphization. The nano-hardness was found to increase rapidly with increasing ion fluence till the dose of 1×1015 ions/cm2, and then gradually saturate with dose. The enhancement of hardness in irradiated materials is due to irradiation-induced defects acting as barriers to dislocation motion.

关键词： Damage structure Zr-Ti-Al alloy 1Cr18Ni9Ti stainless steel XRD TEM Irradiation Depth profile