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Recent advances in controlling the crystallization of two-dimensional perovskites for optoelectronic device

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Frontiers of physics 2019年第5期14卷 1-17页

作者： Shi-qiang Luo Ji-Fei Wang Bin Yang Yong-bo Yuan Hunan Key Laboratory of Super Micro structure and Ultrafast Process School of Physics and ElectronicsCentral South UniversityChangsha 410083China College of Physic and Electric Information Hunan Institute of Science and TechenologyYueyang 414006China College of Materials Science and Engineering Hunan UniversityChangsha 410082China Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology Hunan UniversityChangsha 410082China

Though three-dimensional (3D) organic inorganic halide perovskites (OIHP) is very promising for low cost and distributed PV generation,the stability issue of 3D OIHP is still a problem for its ***-dimensional (2D) perovskites,protected by periodic organic ligands,is promising due to its excellent optoelectronic property and superior ***,2D perovskitc is anisotropic in its crystal structure and optoelectronic properties,and the resulted film is often a mixture of different ***,methods to manipulate 2D perovskitc crystal orientation and its phase separation are *** this review,the major advances on the composition engineering,crystal orientation,phase separa-tion,and inlerfaeial capping are ***,efforts on understanding the formation process of 2D perovskitc crystal arc also discussed,which is important for making full use of 2D perovskitc in functional optoelectronic devices.

关键词： optoelectronic devices perovskite solar cells nanoscale materials chemical vapor deposition

The stabilization effect of the substituted atoms and the magnetism for intermetallic compounds YFe_(12-x)V_x

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Science China(Physics,Mechanics & Astronomy) 2010年第7期53卷 1239-1243页

作者： MA HuanFeng HUANG Zheng CHEN bo qiang WeiRong SUN GuangAi School of Physics Science and Technology Southwest Jiaotong UniversityChengdu 610031China Institute of Nuclear Physics and Chemistry China Academy of Engineering PhysicsMianyang 621900China

Based on the density functional theory(DFT),using linearized augmented plane wave and improved local orbital(APW+lo),the structures and energies of Y,Fe,V,FeV,YFe12-xVx,and Y2Fe17 are optimized and *** is explained that the pure YFe12 with ThMn12-type structure does not exist,and replacing a small fraction of vanadium can stabilize the *** local magnetic moments reveal that the decrease of magnetization of YFe12-xVx does not only correspond to a simple dilution of the iron sublattice magnetization,but also reduce the Fe moments as well with increasing vanadium content.

关键词： YFe12-xVx density functional theory(DFT) magnetic moment stabilization

Performance analysis of ARQ schemes with code combining over Nakagami-m fading channel

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The Journal of China Universities of Posts and Telecommunications 2009年第5期16卷 14-19页

作者： XU Wen-bo NIU Kai LIN Jia-ru HE Zhi-qiang School of Information and Telecommunication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

This article investigates the performance of hybrid automatic repeat request （HARQ） with code combining over the ideally interleaved Nakagami-m fading channel. Two retransmission protocols with coherent equal gain code combining are adopted, where the entire frame and several selected portions of the frame are repeated in protocols I and II, respectively. Protocol II could be viewed as a generalization of the recently proposed reliability-based HARQ. To facilitate performance analysis, an approximation of the product of two independent Nakagami-m distributed random variables is first developed. Then the approximate analysis is utilized to obtain exact frame error probability （FEP） for protocol I, and the upper bound of the FEP for protocol II. Furthermore, the throughput performance of both two protocols is presented. Simulation results show the reliability of the theoretical analysis, where protocol II outperforms protocol I in the throughput performance due to the reduced amount of transmitted information.

关键词： code combining HARQ Nakagami-m fading performance analysis

Transjugular intrahepatic portosystemic shunt versus open splenectomy and esophagogastric devascularization for portal hypertension with recurrent variceal bleeding

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Hepatobiliary & Pancreatic Diseases International 2017年第2期16卷 169-175页

作者： An-Ping Su Zhao-Da Zhang bo-Le Tian Jing-qiang Zhu Department of Thyroid Surgery West China Hospital Sichuan University Chengdu 610041 China Department of Hepatobiliopancreatic Surgery West China Hospital Sichuan University Chengdu 610041 China

BACKGROUND： Transjugular intrahepatic portosystemic shunt（TIPS） and open splenectomy and esophagogastric devascularization（OSED） are widely used to treat patients with portal hypertension and recurrent variceal bleeding（PHRVB）. This study aimed to compare the effectiveness between TIPS and OSED for the treatment of ***： The data were retrospectively retrieved from 479 cirrhotic patients（Child-Pugh A or B class） with PHRVB, who had undergone TIPS（TIPS group） or OSED（OSED group） between January 1, 2010 and October 31, ***： A total of 196 patients received TIPS, whereas 283 underwent OSED. Within one month after TIPS and OSED, the rebleeding rates were 6.1% and 3.2%, respectively（P=0.122）. Significantly lower incidence of pleural effusion,splenic vein thrombosis, and pulmonary infection, as well as higher hepatic encephalopathy rate, shorter postoperative length of hospital stay, and higher hospital costs were observed in the TIPS group than those in the OSED group. During the follow-up periods（29 months）, significantly higher incidences of rebleeding（15.3% vs 4.6%, P=0.001） and hepatic encephalopathy（17.3% vs 3.9%, P=0.001） were observed in the TIPS group than in the OSED group. The incidence of instent stenosis was 18.9%. The survival rates were 91.3% in the TIPS group and 95.1% in the OSED group. The long-term liver function did not worsen after either TIPS or ***： For the patients with liver function in the Child-Pugh A or B class, TIPS is not superior over OSED in terms of PHRVB treatment and rebleeding prevention.

关键词： liver cirrhosis portal hypertension recurrent variceal bleeding transjugular intrahepatic portosystemic shunt open splenectomy and esophagogastric devascularization

Can Classic Avrami Theory Describe the Isothermal Crystallization Kinetics for Stereocomplex Poly(lactic acid)?

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Chinese Journal of Polymer Science 2017年第6期35卷 773-781页

作者：谢兰 Xu-juan Li 熊玉竹 Qin Chen Hai-bo Xie qiang Zheng Department of Polymer and Processing College of Materials and MetallurgyGuizhou UniversityGuiyang 550025China College of Environment and Resource Southwest University of Science and TechnologyMianyang 621010China

Classic Avrami model and its modifications have found diverse applications in describing the thermal and phase behaviors of inorganic metals and organic polymers. The direct introduction of classic Avrami equation to offer quantitative analyses of crystallization kinetic parameters for enantiomeric poly（lactic acid）（PLA） blends may, however, lead to contradictory conclusions. As revealed by this study, during the characterization of isothermal melt and cold crystallization for stereocomplex PLA containing equal-weight poly（L-lactic acid） and poly（D-lactic acid）, the kinetic parameters yielded by Avrami equation are not in line with the classic crystallization hypotheses or the direct morphological observations. The underlying mechanisms, to some extent, lie in the generation of stereocomplex crystals （SCs） during the cooling/heating which affects the subsequent crystallization dynamics. The huge gap between the melting enthalpies of 100% crystalline SCs （142 J/g） and homo-crystals （HCs, 93 J/g） is most likely responsible for the confusing kinetic parameters acquired from the deduction of Avrami equation, which is based on the integration of enthalpies as a function of crystallization time. This prompts for great care that the classic Avrami equation is not applicable to accurately describe the crystallization kinetics of stereocomplex PLA, given the generation of SCs prior to crystallization and the coexistence of HCs and SCs during crystallization.

关键词： Poly(lactic acid) Stereocomplex crystallization Crystallization kinetics Classic Avrami theory

Study on the liquid metal flow field in FC-mold of slab continuous casting

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Advances in Manufacturing 2015年第3期3卷 212-220页

作者： Zhen-qiang Zhang Jian-bo Yu Zhong-Ming Ren Kang Deng School of Materials Science and Engineering Shanghai University

The flow pattern and the velocity distribution of a liquid metal in the flow control mold （FC-mold） were investigated with a mercury model by analogy to the molten steel during continuous casting. The velocity measurement was conducted by the ultrasonic Doppler velocimeter （UDV） under various magnetic distributions and flux densities. The impingement intensity and the scouring intensity of the liquid metal to the narrow wall of the mold were calculated based on the measured data, and the influence of the magnetic flux density on the liquid metal flow in the mold was analyzed. The results showed that the surface of the liquid metal became more active when only the lower magnet was assembled, and the surface fluctuation was suppressed when further applying the upper magnetic field. It was indicated that when the upper and lower magnetic flux densities were 0.18 T and 0.5 T, respectively, the optimum conditions could be obtained, under which the free surface fluctuation could be suppressed, and a flow recirculation could rapidly form.

关键词： FC-mold Continuous casting Electromagnetic brake - Magnetic flux intensity

Production and application of a novel bioflocculant by multiple-microorganism consortia using brewery wastewater as carbon source

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Journal of Environmental Sciences 2007年第6期19卷 667-673页

作者： ZHANG Zhi-qiang LIN bo XIA Si-qing WANG Xue-jiang YANG A-ming State Key Laboratory of Pollution Control and Resource Reuse College of Environmental Science and Engineering Tongji University Shanghai 200092 China College of Environmental -Science and Engineering Nanchang University Nanchang 330031 China

The flocculating activity of a novel bioflocculant MMF1 produced by multiple-microorganism consortia MM1 was investigated. MM1 was composed of strain BAFRT4 identified as Staphylococcus sp. and strain CYGS1 identified as Pseudomonas sp. The flocculating activity of MMF1 isolated from the screening medium was 82.9%, which is remarkably higher than that of the bioflocculant produced by either of the strains under the same condition. Brewery wastewater was also used as the carbon source for MM1, and the cost-effective production medium for MM1 mainly comprised 1.0 L brewery water （chemical oxygen demand （COD） 5000 mg/L）, 0.5 g/L urea, 0.5 g/L yeast extract, and 0.2 g/L （NH4）2SO4. The optimal conditions for the production of MMF1 was inoculum size 2%, initial pH 6.0, cultivating temperature 30℃, and shaking speed 160 r/min, under which the flocculating activity of the MMF1 reached 96.8%. Fifteen grams of purified bioflocculant could be recovered from 1.0 L of fermentation broth. MMF1 was identified as a macromolecular substance containing both protein and polysaccharide. It showed good flocculating performance in treating indigotin printing and dyeing wastewater, and the maximal removal efficiencies of COD and chroma were 79.2% and 86.5%, respectively.

关键词： bioflocculant multiple-microorganism consortia brewery wastewater carbon source indigotin printing and dyeing wastewater

Preparation and characterization of pure SiC ceramics by high temperature physical vapor transport induced by seeding with nano SiC particles

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Journal of Materials Science & Technology 2019年第12期35卷 2756-2760页

作者： Yuchen Deng Yaming Zhang Nanlong Zhang qiang Zhi bo Wang Jianfeng Yang State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong University

High temperature physical vapor transport(HTPVT) was employed to grow polycrystalline SiC ceramics with high density and purity, induced by nano SiC particles as seeds. The obtained SiC ceramics were identified as 6 H-SiC with a mainly preferred orientation along the(0 0 0 6) plane, and an obvious refinement of grain size was demonstrated for the SiC seeds. Mean grain sizes of the obtained SiC ceramics were112 μm and 314 μm, by using the SiC seeds with the mean particle size of 50 nm and 500 nm, respectively,which were obviously smaller than that of the seed-free sample(960 μm). The samples obtained with the seeds also demonstrated enhanced flexural strength and hardness, attributing to the reduced mean grain size. Furthermore, SiC ceramics without seeds via HTPVT exhibited a high thermal conductivity of242 W·(m·K)^-1 at room temperature due to the highly preferred orientation. While the degree of preferred orientation of seed-induced samples was lower, the thermal conductivity of SiC ceramics induced by seeding still maintained at least 200 W·(m·K)^-1 at room temperature, this level was much higher than most other methods. Therefore, seed-induced method appears to be an effective way to control structures and behavior of SiC ceramics through HTPVT.

关键词： Dense silicon carbide Seed-induced Mechanical properties Thermal conductivity HTPVT

Effect of synergistic action of ultrasonic vibration and solidification pressure on tensile properties of vacuum counter-pressure casting aluminum alloy

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China Foundry 2018年第6期15卷 411-417页

作者： Qing-song Yan Gang Lu Gui-ming Luo bo-wen Xiong qiang-qiang Zheng National Defense Key Discipline Laboratory of Light Alloy Processing Science and Tech nologyNanchang Hangkong UniversityNanchang

The effect of synergistic action of ultrasonic vibration and solidification pressure on tensile properties of vacuum counter-pressure casting ZL114 A alloys was studied systemically through testing and analyzing the tensile strength and elongation subjected to different ultrasonic powers and solidification pressures. The results indicate that the synergistic action of ultrasonic vibration and solidification pressure can result in the refinement of grains and improvement of tensile properties. both the highest tensile strength and elongation of aluminum alloy were obtained under synergistic action of 600 W ultrasonic power and 350 kPa solidification pressure. Moreover, the tensile fracture morphology shows obvious ductile fracture characteristics. When the solidification pressure is lower than 300 kPa, the effect of ultrasonic power on tensile strength and elongation is more obvious, but when the solidification pressure is higher than 300 kPa, the effect of solidification pressure on tensile strength and elongation is greater. Meanwhile, the size and morphology of the eutectic silicon were improved significantly by the ultrasonic vibration and pressurized solidification. The strip and massive eutectic silicon phase are completely converted into small short rod-like and evenly distributed Si phases at the grain boundary of primary α-Al.

关键词： ultrasonic power solidification pressure vacuum counter-pressure casting aluminum alloy tensile property