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The hydraulic performance of twin-screw pump

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Journal of Hydrodynamics 2020年第3期32卷 605-615页

作者： Di Zhang Li Cheng Ying-yuan Li wei-xuan Jiao School of Hydraulic Energy and Power EngineeringYangzhou UniversityYangzhou 225009China

Based on the computational fluid dynamics (CFD) and the experiment technology, this paper presents a new type of the twin-screw pump for the water-supply and studies its hydraulic performance with the hydraulic performance test. The internal flow characteristics and the hydraulic performance of the twin-screw pump are numerically simulated. The CFD results show that at different heads, the screw pressure gradually increases from the inlet end face along the axial direction of the screw to the outlet end face. The pressure distribution in the screw groove is relatively uniform, the screw clearance and the meshing area pressure are different from the screw groove pressure distribution. Under the same working condition of the head, the pressure distributions in the screw below and above the design speed are the same as the pressure distribution at the design speed, and with the range of the pressure value quite close. As the rotating speed increases furthermore, the flow rate and the volume efficiency of the pump both increase. At different rotating speeds, the velocity distributions along the axial direction of the screw are similar. A test rig is built, which consists of a closed-loop circuit, and the test results are found in good agreement with the CFD predictions. The experimental results show that the flow rate-head curves of the twin-screw pumps are similar at different rotating speeds. The research shows that the designed twin-screw pump enjoys a higher volumetric efficiency and a lower shaft power when the axial clearance is 0.08 mm-0.12 mm. When the clearance is 0.1 mm, the volumetric efficiency is the highest.

关键词： Twin-screw pump screw-rotor profile hydraulic characteristics screw clearances

Reduction kinetics of MgO-doped calcium ferrites under CO-N2 atmosphere

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Journal of Iron and Steel Research International 2019年第12期26卷 1265-1272页

作者： Tian-xiong Wang Cheng-yi Ding Xue-wei Lv Sen-wei xuan Gang Li Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and New Materials Chongqing UniversityChongqing 400044China School of Materials Science and Engineering Chongqing UniversityChongqing 400044China

The effect of magnesia on calcium ferrite(***2O3)reduction by CO was examined by isothermal *** of calcium ferrite added with 0,2,4,and 8 wt.%magnesia(abbreviated as CF,CF2M,CF4M,and CF8M)were *** composition was analyzed by X-ray diffraction,and the results indicated that CF2M and CF4M are reduced to lower reduction degree and with lower apparent activation energy than CF;and CF8M with more ***2O3 is reduced to a lower degree and with more difficulty compared with *** rate analysis revealed that CF,CF2M,CF4M,and CF8M reductions are all typical two-step reactions with the order of CF→CWF(***2O3)→*** apparent reduction activation energies of CF,CF2M,CF4M,and CF8M are 46.89,37.30,17.30,and 29.20 kJ/mol,*** analysis depicted that CF2M,CF4M,and CF8M reductions are all described by 2D Avrami–Erofeev(A–E)equation(A2)in the whole process,while CF reduction is first expressed by A2 and then by 3D A–E equation(A3).Different from shrinking core model,a new kinetic model for powdery samples reduction was proposed to illustrate the relationship among reduction rates,reduction routes,and model functions.

关键词： Calcium ferrite Magnesia Reduction kinetics Reduction model

Quantitative Analysis of Natural and Human Factors of Oasis Change in the Tail of Shiyang River over the Past 60 Years

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Acta Geologica Sinica(English Edition) 2020年第3期94卷 637-645页

作者： CHEN Yong YANG Guojing ZHOU Lihua LIAO Jie wei xuan Northwest Institute of Eco-Environment and Resources Chinese Academy of SciencesLanzhou 730000China Institutes of Science and Development Chinese Academy of SciencesBeijing 100190China

The human and natural factors complicit in the driving forces of oasis change have always received considerable interest from the international research community. In this study, we used principal component analysis of natural and socio-economic statistical factors to quantitatively analyze the causal relationships and their contributions to the observed periodic expansion or shrinkage of the Minqin Oasis over almost 60 years. Our results show that human factors were the dominant factors governing expansion or shrinkage, with average contributions of 69.38% and 76.16%, respectively. Moreover, policy decisions have been the pivotal human factors. Under the influence of various policies, we have found that water resource utilization, land reclamation, population explosion, ecological protection and economic development have each played leading roles in different periods. This study provides a scientific basis for modelling the dynamics of an oasis for sustainable management.

关键词： Oasis change natural factors human factors Minqin Oasis

Design guidelines for urea hydrolysers for ammonia demand of the SCR DENOX project in coal-fired power plants

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Frontiers in Energy 2013年第1期7卷 127-132页

作者： Peng ZHENG xuan YAO wei ZHENG Beijing GUODIAN Longyuan Environmental Engineering CompanyLimited Beijing 100039 China

Ammonia is highly volatile and will present substantial environmental and operation hazards when leaking into the air. However, ammonia is the most common reactant in the DENOX project to eliminate NOx in the flue gas. The storage and transportation of liquid ammonia has always been a dilemma of the power plant. Urea is a perfect substitute source for ammonia in the plant. Urea hydrolysis technology can easily convert urea into ammonia with low expense. Presently, there is still no self-depended mature urea hydrolysis technology for the DENOX project in China; therefore, this paper proposes several guidelines to design the urea hydrolyser by theoretical analysis. Based on theoretical analysis, a simulation model is built to simulate the chemical reaction in the urea hydrolyser and is validated by the operational data of the commercial hydrolyser revealed in the literature. This paper endeavors to propose suggestions and guidelines to develop domestically urea hydrolysers in China.

关键词： urea hydrolyser ammonia selective catalytic reduction (SCR)

Progress in immunotherapy for neuroendocrine neoplasm of the digestive system

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World Journal of Gastroenterology 2023年第26期29卷 4174-4185页

作者： wei-xuan Pan Xin-Mu Zhang Shao-Long Hao wei Han Department of General Surgery Beijing Luhe HospitalCapital Medical UniversityBeijing 101100China Department of Liver Surgery State Key Laboratory of Complex Severe and Rare DiseasesPeking Union Medical College HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100730China

Neuroendocrine neoplasms(NENs)are rare heterogeneous tumors that can develop in almost any organ,with the digestive organs,including the gastrointestinal tract and pancreas being the most commonly affected *** the fact that advances in initial therapies have progressed,there is presently no recognized effective treatment for advanced *** checkpoint inhibitors(ICIs)have shown superior efficacy in treating several types of solid *** their successful role in the treatment of partial NENs,such as small cell lung cancer,and Merkel cell carcinoma,the role of ICIs in most of the NENs remains ***,due to their specific anti-tumor mechanisms and acceptable safety profile,ICIs are a promising avenue for further study in NENs *** clinical trials have illustrated that combination therapy with ICI is more efficient than monotherapy,and multiple clinical trials are constantly ongoing to evaluate the efficacy and safety of these combination ***,the purpose of this review is to provide a comprehensive summary of the clinical progress of immunotherapy in NENs affecting the digestive system,with a specific emphasis on the application of programmed cell death protein 1/programmed death receptor ligand 1 ***,this review has an exploration of the potential beneficiary population and the inherent value of utilizing immunotherapy in the management of NENs.

关键词： Immunotherapy PD-1 inhibitor Neuroendocrine neoplasm Neuroendocrine tumor Neuroendocrine carcinoma Gastrointestinal Pancreatic

Design of Waveguide Integrated Ge-Quantum-Well Electro-Absorption Modulators

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Chinese Physics Letters 2011年第1期28卷 102-105页

作者： ZHAO Hong-wei HU wei-xuan XUE Chun-Lai CHENG Bu-Wen WANG Qi-Ming State Key Laboratory of Integrated Optoelectronics Institute of Semiconductors Chinese Academy of Sciences Beijing 100083

We present two designs for a waveguide Oe-quantum-well electro-absorption modulator. In our designs, the strip SOI waveguides are butt-coupled and evanescent-coupled to the modulator, respectively. The proposed Gequantum-weB electro-absorption modulator is based on quantum-confined Stark effect （QCSE）, having a 3-dB bandwidth above 50GHz, as well as a low switching power （around 60fJ/bit at 1435nm）. In the butt-coupled design, the optimized extinction ratio is up to 11.4 dB, while the insertion loss is only 6. 74 dB. For the second one, which utilizes evanescent coupling, the extinction ratio and insertion loss are 9.18 dB and 6. 72 dB, respectively.

关键词： Optics quantum optics and lasers

Expression of c-fos and oxidative stress on brain of rats reared on food from mercury-selenium coexisting mining area

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Journal of Environmental Sciences 2006年第4期18卷 788-792页

作者： CHENG Jin-ping HU wei-xuan LIU Xiao-jie ZHENG Min SHI wei WANG Wen-hua School of Environmental Science and Engineering Shanghai Jiaotong University Shanghai 200240 China Department oi Epidemiology National Institute for Minamata Disease Minamata Kumamoto 867-0008 Japan School of Public Heath Fudan University Shanghai 200032 China

Wanshan mercury mine is the largest mercury deposit in Guizhou Province of China, but there were few reports on mercury toxic＂ effect in the mining area. In order to study the neurotoxicity of food from Wanshan mercury mine area and probe into the effect of food from Wanshan mercury miner area on the changes of brain oxidative damage and expression of c-fos gene. The rats were exposed to mercury contaminated food for 20 d. The content of malondialdehyde （MDA）, superoxide dismutase （SOD）, GSH-peroxidase （GSH-px） and Glutathione （GSH） in rat brain was measured, and the effect of mercury contaminated rice on the expression of c-los mRNA in rat brain and the expression of c-FOS protein in cortex, hippocampus were observed using reverse transcription polymerase chain reaction （RT-PCR） and immunocytochemical methods. The results showed the levels of GSH, MDA, SOD and of GSH-dependent enzymes in the rat brain changed between exposure groups and control group; The mercury polluted rice induced significantly the expression of c-los mRNA; the c-FOS positive cells in hippocampus and cortex of exposure groups were significant different from control group （P〈0.01）. It could be concluded that oxidative stress signals could contribute to the induction of immediate early genes （IEGs）; free radicals and their by-products might not only cause oxidative damage, but also influenced gene expression; IEGs c-fos participated in the toxicity process of brain injury by mercury polluted food.

关键词： Wanshan mercury mine mercury polluted food oxidative damage c-fos

New bainite kinetics of high strength low alloy steel in fast cooling process

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Journal of Iron and Steel Research International 2017年第2期24卷 229-233页

作者： xuan-wei Lei Ji-hua Huang Shu-hai Chen Xing-ke Zhao School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Based on Kolmgorov-Johnson-Mehl-Avrami analysis, a new bainite kinetics of high strength low alloy steel in fast cooling process was developed by utilizing different experimental methods. Upper bainite transformation morphological evolutions at a cooling rate of 8.3 K/s were directly observed by laser scanning confocal microscopy. This qualitative analysis suggests that bainite packet is more suitable to give a one-dimensional growth model if it is considered as a transformation unit. The nucleation rate of bainite packets in fast cooling process is assumed to give an a priori item. One-dimensional growth model with constant growth rate which is assumed as a function of cooling rate is adopted as well. Thus, the devel- oped new bainite kinetics is simple in expression and contains an adjustable parameter and an empirical pa rameter. Experimental results show upper bainite and lower bainite transformations in fast cooling processes. Their referential phase volume fractions are calculated by the expanded lever rule on the first derivative dilatometer curves. For the similar transformation mechanisms, upper bainite and lower bainite are considered to give the same kinetics. With considering the Nakamura＇s equation, the bainite kinetics is fitted with experimental data. Results show that bainite volume fractions and bainite transformation rates can be expressed precisely bY the newly developed bainite kinetics.

关键词： Bainite kinetics Fast cooling process High strength low alloy steel Upper bainite Lower bainite

Rice roots avoid asymmetric heavy metal and salinity stress via an RBOH-ROS-auxin signaling cascade

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Molecular Plant 2023年第10期16卷 1678-1694页

作者： Han-Qing Wang Xing-Yu Zhao wei xuan Peng Wang Fang-Jie Zhao State Key Laboratory of Crop Genetics&Germplasm Enhancement and Utilization College of Resources and Environmental SciencesNanjing Agricultural UniversityNanjing 210095China

Root developmental plasticity is crucial for plants to adapt to a changing soil environment,where nutrients and abiotic stress factors are distributed *** plant roots sense and avoid heterogeneous abiotic stress in soil remains ***,we show that,in response to asymmetric stress of heavy metals(cadmium,copper,or lead)and salt,rice roots rapidly proliferate lateral roots(LRs)in the stress-free area,thereby remodeling root architecture to avoid localized *** and quantitative analyses of reactive oxygen species(ROS)showed that asymmetric stress induces a ROS burst in the tips of the exposed roots and simultaneously triggers rapid systemic ROS signaling to the unexposed *** of a ROS scavenger to either the stressed or stress-free area abolished systemic ROS signaling and LR proliferation induced by asymmetric *** stress also enhanced cytosolic calcium(Ca^(2+))signaling;blocking Ca^(2+)signaling inhibited systemic ROS propagation and LR branching in the stress-free *** identified two plasma-membrane-localized respiratory burst oxidase homologs,OsRBOHA and OsRBOHI,as key players in systemic ROS signaling under asymmetric *** of OsRBOHA and OsRBOHI in roots was upregulated by Cd stress,and knockout of either gene reduced systemic ROS signaling and LR proliferation under asymmetric ***,we demonstrated that auxin signaling and cell wall remodeling act downstream of the systemic ROS signaling to promote LR ***,our study reveals an RBOH-ROS-auxin signaling cascade that enables rice roots to avoid localized stress of heavy metals and salt and provides new insight into root system plasticity in heterogenous soil.

关键词： root system architecture heterogenous abiotic stress reactive oxygen species signaling