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金属间化合物DyMn2Ge2的自发磁相变和场诱导的磁相变

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物理学报 2001年第2期50卷 313-318页

作者：郭光华 levi.,RZ 中南工业大学应用物理与热能工程系，长沙410083 Department

在10—800K的温度范围内用X射线衍射方法测量了DyMn2Ge2化合物的晶格常数与温度的变化关系，观察到高温时DyMn2Ge2由顺磁状态到反铁磁状态的自发磁相变伴随着晶格常数a的负的磁弹性异常现象. 在4.2K—200K的温度范围内测量了DyMn2Ge2的... 详细信息

在10—800K的温度范围内用X射线衍射方法测量了DyMn2Ge2化合物的晶格常数与温度的变化关系，观察到高温时DyMn2Ge2由顺磁状态到反铁磁状态的自发磁相变伴随着晶格常数a的负的磁弹性异常现象. 在4.2K—200K的温度范围内测量了DyMn2Ge2的交流磁化率. 在交换相互作用的分子场模型近似下，从理论上分析讨论了DyMn2Ge2的低温自发磁相变和场诱导的磁相变. 计算了DyMn2Ge2单晶的磁化强度与温度的变化关系以及不同温度下外磁场沿晶轴c方向时的磁化曲线. 理论分析和计算结果表明，温度低于33K时在DyMn2Ge2中观察到的场诱导的一级磁相变为由亚铁磁状态(Fi)到中间态(IS)相变.

关键词：稀土-过渡族金属间化合物磁结构磁相变场诱导

A NEAR-INFRARED FLUORESCENT DEOXYGLUCOSE DERIVATIVE FOR OPTICAL IMAGING OF EXPERIMENTAL ARTHRITIS

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Journal of Innovative Optical Health Sciences 2009年第2期2卷 179-187页

作者： XIUPING LIU ZHENGMING XIONG SHEEN-WOO LEE JELENA levi SHAHRIAR YAGHOUBI SANDIP BISWAL SANJIV SAM GAMBHIR ZHEN CHENG School of Life Science&Technology Huazhong University of Science and Technology Wuhan 430074 China Molecular Imaging Program at Stanford(MIPS)Departments of Radiology and Bioengineering Bio-X Program Stanford UniversityCalifornia 94305USA

The purpose of this study is to investigate whether a near-infrared fluorescence(NIRF)probe,Cy5.5-d-glucosamine(Cy5.5-2DG),can image arthritis in collagen-induced arthritic(CIA)*** presence of arthritis was verified by both visual examination and micro-computed tomography(MicroCT)*** mice were imaged by a micro-positron emission tomography(MicroPET)scanner one hour after intravenous injection of 2-deoxy-2-[18F]fluoro-d-glucose([18F]FDG).After radioactivity of[18F]FDG decayed away,Cy5.5-2DG was injected into a lateral tail vein of the *** tissue targeting and retention of Cy5.5-2DG in CIA mice were evaluated and quantified by an optical imaging *** tissue in CIA mice was clearly visualized by[18F]FDG-MicroPET *** imaging of Cy5.5-2DG in the same mice revealed that the pattern of localization of Cy5.5-2DG in the arthritic tissue was very similar to that of[18F]*** analysis further showed that[18F]FDG uptake in arthritic tissues at one hour post-injection(p.i.)and Cy5.5-2DG uptakes at different time points *** all well correlated(r2 over 0.65).In conclusion,Cy5.5-DG can detect arthritic tissues in living *** good correlation between the[18F]FDG uptake and Cy5.5-2DG accumulation in the same arthritic tissue warrants further investigation of Cy5.5-2DG as an approach for assessment of anti-inflammatory treatments.

关键词： Near-infrared fluorescence arthritis fluorescent deoxyglucose FDG

Biliary-colonic fistula caused by cholecystectomy bile duct injury

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Hepatobiliary & Pancreatic Diseases International 2013年第4期12卷 443-445页

作者： Francisco Igor B Macedo Victor J Casillas James S Davis Joe U levi Danny Sleeman Dewitt Daughtry Family Department of Surgery University of Miami Miller School of Medicine and Ryder Trauma Center/Jackson Memorial HospitalMiami Florida USA Department of Radiology University of Miami Miller School of Medicine and Ryder Trauma Center/Jackson Memorial HospitalMiami Florida USA

Biliary-colonic fistula is a rare complication after laparoscopic cholecystectomy. We present a case of post-cholecystectomy iatrogenic biliary injury that resulted in a fistula between the common hepatic duct and large bowel. Magnetic resonance cholangiopancreatography provided good visualization of injury even with concurrent normal level of alkaline phosphatase. Radiologic findings and surgical management of this condition are discussed in detail.

关键词： cholecystectomy magnetic resonance imaging biliary tract disease

Study of Natural Radioactivity of Groundwater in Sango-Ilorin, Nigeria

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Journal of Physical Science and Application 2012年第8期2卷 289-295页

作者： levi Ikechukwu Nwankwo Department of Physics University of llorin P.M.B. 1515 Ilorin Nigeria

Gamma spectrometric method was used to determine the natural radioactivity of the groundwater obtained from hand dug wells in Sango-Ilorin, North Central Nigeria. The purpose of the study is to ascertain whether the groundwater radioactivity level in the area that was previously used as a waste dumpsite and farmland poses any significant health hazard to the populace. The main radionuclides analysed in the samples were 226Ra and 22SRa （progenies of 218Su and 232Th respectively）, and the naturally occurring 40K. The activity concentrations of the radionuclides range from 0.02 to 7.35 Bql1 for 226Ra with a mean of 4.04 ± 0.18 Bql-1, 0.009 to 3.98 Bql-1 for 22SRa having a mean of 0.77 - 0.09 Bql-1. 40K concentration ranges from 0.45 to 30.14 Bq1-1 and has a mean of 4.81 ± 0.62 Bql1. The derived Annual Effective Dose received by the population as a result of the ingestion of 40K is estimated to range from 0 to 0.01 mSvy-1 with an average of 0.01 and standard deviation of 0.02 mSvyl; 226Ra ranged from 0 to 0.8 mSvy-1 with an average of 0.41 and standard deviation of 0.23 mSvy-1 and 228Ra ranged from 0 to 1 mSvy-1 with an average of 0.2 and standard deviation of 0.31 mSvy-1. The results show that the calculated average annual effective dose/ingestion dose for some of the wells are above WHO recommended level of 0.1 mSvylfor drinking water but falls within the tolerable level of 1 mSv/yr to the general public for prolonged exposure as recommended by ICRP. Therefore, it is suggested that detailed radiological monitoring be conducted in the area.

关键词： Radioactivity groundwater gamma ray spectrometer Nigeria health hazard.

Synthesis and characterization of BaTiO_3/α-Fe_2O_3 core/shell structure

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Journal of Advanced Ceramics 2019年第1期8卷 133-147页

作者： Suzana FILIPOVI? Vera P.PAVLOVI? Miodrag MITRI? Steva levi? Neboj?a MITROVI? Aleksa MARI?I? Branislav VLAHOVI? Vladimir B.PAVLOVI? Institute of Technical Sciences of Serbian Academy of Sciences and Arts Faculty of Mechanical Engineering University of Belgrade "Vin?a" Institute of Nuclear Sciences University of Belgrade Faculty of Agriculture University of Belgrade Faculty of Technical Sciences ?a?ak University of Kragujevac North Carolina Central University NASA University Research Center for Aerospace Device Research and Education and NSF Center of Research Excellence in Science and Technology Computational Center for Fundamental and Applied Science and Education

Multiferroic materials attracted a lot of attention in recent years because of their significant scientific interest and technological applications. The multiferroic core/shell powders have a better connectivity between the phases, resulting in superior dielectric and magneto electric properties. In this study, the influence of preparation condition on structure and properties of BaTiO_3/α-Fe_2 O_3 core/shell composite materials was examined. The five samples were obtained by varying synthesis conditions, such as synthesized method(co-precipitation and sonochemical method) and pH values of solution. XRD and Raman spectroscopy analyses were performed in order to determine phase composition and structural changes within samples. Morphology modifications were examined by SEM and EDS analyses. Finally, effect of structural and microstructural changes on magnetic and electrical properties was detected and explained.

关键词： ceramics electronic materials magnetic materials Raman spectroscopy X-ray diffraction(XRD) ferroelectricity

Nonlinear wake amplification by an active medium in a cylindrical waveguide using a modulated trigger bunch

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High Power Laser Science and Engineering 2014年第3期2卷 91-101页

作者： Zeev Toroker Miron Voin levi Schchter Department of Electrical Engineering TechnionIsrael Institute of TechnologyHaifa 32000Israel

Cerenkov wake amplification can be used as an accelerating scheme,in which a trigger bunch of electrons propagating inside a cylindrical waveguide filled with an active medium generates an initial wake *** to the multiple reflections inside the waveguide,the wake may be amplified significantly more strongly than when propagating in a boundless *** far away from the trigger bunch the wake,which travels with the same phase velocity as the bunch,reaches saturation and it can accelerate a second bunch of electrons trailing *** a CO2 gas mixture our numerical and analytical calculations indicate that a short saturation length and a high gradient can be achieved with a large waveguide radius filled with a high density of excited atoms and a trigger bunch that travels at a velocity slightly above the Cerenkov *** obtain a stable level of saturated wake that will be suitable for particle acceleration,it is crucial to satisfy the single-mode resonance condition,which requires high accuracy in the waveguide radius and the ratio between the electron phase velocity and the Cerenkov *** single-mode propagation our model indicates that it is feasible to obtain gradients as high as GV m-1 in a waveguide length of cm.

关键词： laser–plasma interaction novel optical material and device

Can‘Hero’Save the Pandemic Film Genre in China?

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The World of Chinese 2023年第1期 110-114页

作者： Dylan levi King 不详

At some point,not very far into the future,a review of a Chinese movie about the Covid-19 pandemic might need to start with a lengthier explanation of the epidemiology of the virus,the sociology of city and apartment complex lockdowns,the heroism of nurses,doctors,and food delivery workers,the physiology of a cotton swab up the nostril,and the economics of mask distribution.

关键词： nurse workers cotton

We’ve Got the Power: A Framework for Real-Time Network Power Monitoring

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Journal of Computer and Communications 2020年第5期8卷 75-88页

作者： Rahil Gandotra levi Perigo Interdisciplinary Telecom Program University of Colorado Boulder Boulder USA Department of Computer Science University of Colorado Boulder Boulder USA

The energy consumption of the information and communication technology sector has become a significant portion of the total global energy consumption, warranting research efforts to attempt to reduce it. The pre-requisite for effectual energy management is the availability of the current power consumption values from network devices. Previous works have attempted to estimate and model the consumption values or have measured it using intrusive approaches such as using an in-line power meter. Recent trends suggest that information models are being increasingly used in all aspects of network management. This paper presents a framework developed for enabling the collection of real-time power consumption information from the next generation of networking hardware non-intrusively by employing information models. The experiment results indicate that it is feasible to gather power consumption data using standardized IETF information models, or non-standard customized information models, or through abstracting and exposing the information in a uniform format when no support for the required information models exists. Functional validation of the proposed framework is performed and the results from this research could be leveraged to make energy-efficient network management decisions.

关键词： Energy Management Real-Time Monitoring Information Models Python MIB YANG API

CHAR ACTERISTICS OF TROPICAL CYCLONE GENESIS FORECASTS AND UNDERDISPERSION IN HIGH-RESOLUTION ENSEMBLE FORECASTING WITH A STOCHASTIC KINETIC ENERGY BACKSCATTER SCHEME

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Tropical Cyclone Research and Review 2014年第4期3卷 203-217页

作者： levi Thatcher Zhaoxia Pu Department of Atmospheric Sciences University of UtahSalt Lake CityUtahUSA

This study evaluates ensemble forecasts with a stochastic kinetic energy backscatter scheme(SKEBS)to predict tropical cyclone(TC)genesis and also to characterize the related ensemble *** sets of ensemble forecasts are generated using an advanced research version of the Weather Research and Forecasting model at 5 km horizontal resolution to predict the genesis of Hurricane Ernesto(2006)and Typhoon Nuri(2008).Ensemble forecasts with SKEBS are compared against a control ensemble forecast with the WRF model using downscaled initial conditions derived from the NCEP Global Ensemble Forecasting *** is found that ensemble forecasts with SKEBS are able to generate probabilistic forecasts for TC genesis and also capable of indicating the forecast *** with the deterministic forecast that fails to predict the genesis of Typhoon Nuri,the ensemble forecast with SKEBS is able to produce the genesis ***,the underdispersion of ensemble forecasts with SKEBS is also present in all cases in terms of the simulation period and over the whole model domain,TC environment,and inner core regions,although it is reduced near the TC inner core *** addition,the initial perturbation–based ensemble forecasts shows slightly less underdispersion compared with the SKEBS ensembles.

关键词： tropical cyclone genesis stochastic kinetic energy backscatter ensemble forecasting WRF