检索结果-南通市图书馆

A novel regulatory region controls IgH locus transcription and switch recombination to a subset of isotypes

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

cellular & molecular Immunology 2019年第11期16卷 887-889页

作者： Rocío Amoretti-Villa mélanie Rogier Isabelle Robert Vincent heyer Bernardo Reina-San-martin Institut de Génétique et de Biologie moléculaire et cellulaire(IGBmc) IllkirchFrance Institut National de la Santéet de la Recherche médicale(INSERm) U1258IllkirchFrance centre National de la Recherche Scientifique(cNRS) UMR7104IllkirchFrance Universitéde Strasbourg IllkirchFrance

class switch recombination(cSR)occurs at the IgH locus and replaces the immunoglobulin(Ig)isotype expressed from Igm to IgG,IgE or IgA,endowing the B cell receptor with novel effector *** is triggered by activation-induced cytidine deaminase(AID),1 an enzyme that deaminates cytosines to uracils in single-stranded DNA exposed by *** distinct antibody isotypes are encoded in the IgH locus in individual transcription units composed of a cytokine-inducible promoter,an intronic exon,and a switch region(Sx),followed by the exons encoding the constant region(cx)(Fig.S1a).During cSR,the choice of recombination to a particular isotype is determined by the stimulation-dependent activation of specific promoters,triggering the generation of noncoding germline transcripts(GLTs).2 Thus far,the transcriptional regulation of the IgH locus is known to be controlled by the Eμenhancer,located downstream of the variable region and upstream of the donor switch region(Sμ),and the 3′regulatory region(3′RR)super-enhancer located downstream of cα.

关键词： IgH stimulation replace

mitigation Options for methane, Nitrous Oxide and NitricOxide Emissions from Agricultural Ecosystems

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2000年第1期17卷 83-92页

作者：郑循华王明星王跃思沈壬兴李晶 J.heyer m.Koegge H.Papen 金继生李老土 LAPc Institute of Atmospheric Physics Chinese Academy of Sciences Beijing

An experimental study on mitigation of greenhouse gas (cH4, N2O and NO) emission has been conducted in a typical cropping system of Southeast china for 4 years. By simultaneous measurement, the cH4, N2O and NO emission fluxes from rice-wheat rotation fields, effects of fertilization, water management, temperature and soil moisture were investigated. Temperature, fertilization and water status were found to be the key factors to regulate cH4, N2O and NO emis-sions. Based on the experimental results, some agricultural measures were recommended as techni-cal options to mitigate greenhouse gas emissions from rice-wheat rotation ecosystems. These miti-gation measures are reducing mineral N input, coupling organic manure with chemical fertilizers, applying fertilizers which release available N slowly during periods with intensive plant activity, and applying dry fermented organic manure and well management of water and fertilizer. Key words mitigation options - Emission - Greenhouse gases - Ecosystems This study was supported by projects “ Experimental and modeling Study on N2O Emission from the Rice-Wheat Rotation Fields of Southeast china” and “ Experimental and modeling Study on NO Emission from croplands” , which were granted by the National Natural Science Foundation of china, the State Key Fundamental Research Project “ Predicting the Future (20–50 years) Trend of Environmental change in china”, and the project of chinese Academy of Sciences “ Theory and methodology on Air Pollution Prediction”.Thanks are due to Professor Zhang Wen, Dr. Bai Jianhui, mr. Gong Yanbang, mrs. Luo Dongmei and mr. Liu Guangren from the Institute of Atmospheric Physics, chinese Academy of Sciences for their help in experiments.

关键词： mitigation options Emission Greenhouse gases Ecosystems

Butt-welding Residual Stress of Heat Treatable Aluminum Alloys

在线全文

学校读者我要写书评

暂无评论

Journal of materials Science & Technology 2007年第2期23卷 217-222页

作者： c.m. cheng Department of Industrial Education National Taiwan Normal University Taipei Taiwan China　

This study, taking three types of aluminum alloys 2024-T351, 6061-T6 and 7075-T6 as experimental materials, conducted single V-groove GTAW （gas tungsten arc welding） butt-welding to analyze and compare the magnitude and differences of residual stress in the three aluminum alloys at different single V-groove angles and in restrained or unrestrained conditions. The results show that the larger the grooving angle of butt joint, the higher the residual tensile stress. Too small grooving angle will lead to dramatic differences due to the amount of welding bead filler metal and pre-set joint geometry. Therefore, only an appropriate grooving angle can reduce residual stress. While welding, weldment in restrained condition will lead to a larger residual stress. Also, a residual stress will arise from the restraint position. The ultimate residual stress of weldment is determined by material yield strength at equilibrium temperature. The higher the yield strength at equilibrium temperature, the higher the material residual stress. Because of its larger thermal conductivity, aluminum alloy test specimens have small temperature differential. Therefore, the residual tensile stress of all materials is lower than their yield strength.

关键词： Residual stress Hole-drilling strain-gage method Aluminum alloy Single-V groove

Detection of Breaking Waves Using X-Band Pulse Radar in the Nearshore Region

在线全文

学校读者我要写书评

暂无评论

china Ocean Engineering 2013年第4期27卷 549-556页

作者： Y.c.Lin c.c.chang m.c.Lee H.c.chan J.m.Leu Department of Hydraulic and Ocean Engineering National Cheng-Kung University Department of Soil and Water conservation National Chung Hsing University Department of Hospitality management Taiwan Shoufu University

An X-band pulsed Doppler microwave radar has been used to determine the characteristics of breaking waves. Field experiments were conducted at the Shuang-Si estuary in the north of Taiwan in the winter of 2005. Analyses on maxima radar cross section and Doppler frequency shift are done to characterize wave breaking zones. Based on observations of breaking waves, the wave breaking zones are shown to be located at water depths of 1.8 to 2.2 m in the experimental site. In general, the results indicate that a radar system has the potential to delineate the spatial variation of breaking waves clearly and that this is sufficient to achieve a measurement operation for near-shore air-sea interaction events.

关键词： radar Doppler effect wave breaking coastal zone

mixing features in an electromagnetic rectangular micromixer for electrolyte solutions

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2017年第4期29卷 668-678页

作者： m.m.Wen c.N.Kim Department of mechanical Engineering Graduate School Kyung Hee University Department of mechanical Engineering College of Engineering Kyung Hee University

In this study, a new magnetohydrodynamic（mHD） mixer for electrolyte solutions with pumping function is reported, and the mixing performance of the device for two different electrolyte solutions is numerically examined in a uniform magnetic field. Application of different potentials to different electrodes allows the current to be induced. The combination of the induced current and magnetic field yields Lorentz force, resulting in the fluid motion. The numerical simulation for the flows in the device is carried out with commercial software cFX. The validity of cFX code for the present numerical model is presented. The mixing performance of the fluids is investigated in many different cases with different combinations of input voltage of the electrode. This study shows that the mixing performance can be enhanced by applying spatially alternating positive and negative voltages to the electrodes. The present simulation results show that with a magnetic field intensity lower than 0.5 T, a voltage difference smaller than 2.0 V, and an electric conductivity of electrolyte solution of 1.5 S/m the pumping capabilities ranging 1.6×10^（-7）-3.6×10^（-6） kg/s and the mixing indexes higher than 0.90 can be obtained with sophisticated designs of the micromixer.

关键词： mixer electrolyte solution Lorentz force cFX

Hard rock tunnel boring machine penetration test as an indicator of chipping process efficiency

在线全文

学校读者我要写书评

暂无评论

Journal of Rock mechanics and Geotechnical Engineering 2017年第4期9卷 611-622页

作者： m.c. Villeneuve Department of Geological Sciences University of Canterbury Christchurch 8140 New Zealand

The transition from grinding to chipping can be observed in tunnel boring machine(TBm) penetration test data by plotting the penetration rate(distance/revolution) against the net cutter thrust(force per cutter) over the full range of penetration rates in the *** penetration test data to the geological and geomechanical characteristics of rock masses through which a penetration test is conducted provides the ability to reveal the efficiency of the chipping process in response to changing geological *** test data can also be used to identify stress-induced tunnel face *** research shows that the strength of the rock is an important parameter for controlling how much net cutter thrust is required to transition from grinding to *** also shows that the geological characteristics of a rock will determine how efficient chipping occurs once it has *** particular,geological characteristics that lead to efficient fracture propagation,such as fabric and mica contents,will lead to efficient *** findings will enable a better correlation between TBm performance and geological conditions for use in TBm design,as a basis for contractual payments where penetration rate dominates the excavation cycle and in further academic investigations into the TBm excavation process.

关键词： Penetration rate Grinding chipping Geological characteristics Face stability

Hydrodynamics of the interceptor on a 2-D flat plate by cFD and experiments

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2015年第6期27卷 919-933页

作者： mANSOORI m. FERNANDES A.c. Department of Naval and Ocean Engineering Federal University of Rio de Janeiro

Nowadays, the use of interceptor by both partial and total dynamic lift crafts is quite common. In this article, a lot of evidence is given regarding the effectiveness of interceptor. The interceptor, when placed at the stern region, changes the pressure distribution around the craft. Its presence affects drag force, lifting force and the position of pressure＇s center leading to a new trim. This study focuses on hydrodynamic effects of interceptors on a 2-D fiat plate based on both computational fluid dynamic （cFD） and experimental approaches. The Reynolds average Navier-Stokes （RANS） equations are used to model the flow around a fixed flat plate with an interceptor at different heights and attack angles. Based on finite volume method and SImPLE algorithm which uses static structures, this model can be analyzed and the RANS results can be compared with the experimental data obtained in the current channel of the laboratory of waves and current of cOPPE/UFRJ （LOc in Portuguese acronym）. According to the results, the increase of pressure at the end of the flat plate was proportional to the interceptor height. In addition, the existence of interceptors can significantly increase the lift force coefficient at high angles of attack also proportional to the interceptor height. The presence of interceptor at the end of the fiat plate increased both the lift coefficient and the drag coefficient but hydrodynamic drag did not grow as fast as the lift coefficient did. The lift coefficient increased much more. Furthermore, the results showed that the interceptor effectiveness is proportional to the boundary layer thickness at the end of the fiat plate. As the interceptor was inside the boundary layer alterations of flow speed led to changes in boundary layer thickness, directly affecting interceptor＇s efficiency. Optimum choice of interceptor height had a great effect on its efficiency, and in choosing it the flow speed and length of the boat must be taken into consideration.

关键词： interceptor craft 2-D fiat plate lifting coefficient Reynolds average Navier-Stokes (RANS) pressure distribution,computational fluid dynamic drag

A code-independent technique for computational verification of fluid mechanics and heat transfer problems

在线全文

学校读者我要写书评

暂无评论

Acta mechanica Sinica 2008年第4期24卷 387-397页

作者： m.Garbey c.Picard Department of computer Science University of Houston Houston TX 77204 USA

The goal of this paper is to present a versatile framework for solution verification of PDE＇s. We first generalize the Richardson Extrapolation technique to an optimized extrapolation solution procedure that constructs the best consistent solution from a set of two or three coarse grid solution in the discrete norm of choice. This technique generalizes the Least Square Extrapolation method introduced by one of the author and W. Shyy. We second establish the conditioning number of the problem in a reduced space that approximates the main feature of the numerical solution thanks to a sensitivity analysis. Overall our method produces an a posteriori error estimation in this reduced space of approximation. The key feature of our method is that our construction does not require an internal knowledge of the software neither the source code that produces the solution to be verified. It can be applied in principle as a postprocessing procedure to off the shelf commercial code. We demonstrate the robustness of our method with two steady problems that are separately an incompressible back step flow test case and a heat transfer problem for a battery. Our error estimate might be ultimately verified with a near by manufactured solution. While our pro- cedure is systematic and requires numerous computation of residuals, one can take advantage of distributed computing to get quickly the error estimate.

关键词： Solution verification PDE's Navier Stokes ·Heat transfer. Aposteriori estimate·Distributed computing

modelling mechanical Properties in Native and Biomimetically Formed Vascular Grafts

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2009年第4期6卷 371-377页

作者： m.mandru c.Ionescu m.chirita University of medicine and Pharmacy Faculty of Biomedical EngineeringUniversity street 16700115 IasiRomania Ghent University Department of Electrical energySystems and AutomationTechnologiepark 913B9052GentBelgium

The paper presents a detailed analysis of experimental data in order to characterize the elastic properties of *** analysis would provide a good basis for evaluation of biomimetic vascular *** the latter needs to exhibit similar properties of native tissue,it is important to accurately characterize the biomimetic sample in a large range of applied stresses. The stress-strain properties vary according to the specific pathology(***,aneurism)and the tissue graft must be chosen *** models are proposed in this paper on the stress-strain *** extension for frequency-domain analysis is provided for one of the *** comparison between vascular grafts and native tissue for carotid and thoracic arteries in pigs are in good agreement with results from *** proposed experimental method offers suitable parameters for identifying models which characterize both elasticity and stiffness properties of the analyzed tissues(stress-strain).The proposed models show good performance in characterizing the intrinsic material properties.

关键词： biomimetic biomaterials vascular graft native and artificial tissues stress-strain modeling