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Nanotribological studies using nanoparticle manipulation: Principles and application to structural lubricity

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Friction 2014年第2期2卷 114-139页

作者： dirk DIETZEL Udo DSCHWARZ AndréSCHIRMEISEN Institute of Applied Physics(IAP) Justus-Liebig-Universität GiessenGermany Departments of Mechanical Engineering&Materials Science and Chemical&Environmental Engineering and Center for Research on Structures and Phenomena(CRISP) Yale UniversityNew HavenCTUSA

The term“structural lubricity”denotes a fundamental concept where the friction between two atomically flat surfaces is reduced due to lattice mismatch at the *** favorable circumstances,its effect may cause a contact to experience ultra-low friction,which is why it is also referred to as“superlubricity”.While the basic principle is intriguingly simple,the experimental analysis of structural lubricity has been *** of the main reasons for this predicament is that the tool most frequently used in nanotribology,the friction force microscope,is not well suited to analyse the friction of extended *** overcome this deficiency,substantial efforts have been directed in recent years towards establishing nanoparticle manipulation techniques,where the friction of nanoparticles sliding on a substrate is measured,as an alternative approach to nanotribological *** choosing appropriate nanoparticles and substrates,interfaces exhibiting the characteristics needed for the occurrence of structural lubricity can be *** a consequence,nanoparticle manipulation experiments such as in this review represent a unique opportunity to study the physical conditions and processes necessary to establish structural lubricity,thereby opening a path to exploit this effect in technological applications.

关键词： Nanotribology nanoparticle manipulation friction force microscopy structural lubricity superlubricity HOPG

Smoking prevalence in the area of responsibility of the German Ministry of Defense——results of the employee survey in the context of occupational health management

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Military Medical Research 2020年第3期7卷 343-349页

作者： Stefan Sammito Annika Claus dirk-Matthias Rose Department I 3 Research&Development Air Force Centre of Aerospace MedicineCologneGermany Occupational Medicine Faculty of MedicineOtto-von-Guericke-University of MagdeburgMagdeburgGermany Institute for Teachers’Health Institute of OccupationalSocial and Environmental Medicine of the Johannes-Gutenberg University MainzMainzGermany

Background:Tobacco use,correlated with reduced physical fitness,is one of the leading causes of avoidable death *** increases the risk of dementia and can shorten the lifespan by 10 *** the German Armed Forces(Bundeswehr),figures on smoking behavior have not been comprehensively *** study analyzes current data in a large sample from this ***:Based on an employee survey as part of the Occupational Health Management System,data on smoking behavior from 13,326 participants were analyzed in relation to age,gender,professional status,education level and membership in military operational units versus other ***:Smoking behavior varied significantly(Polder),gender,professional status,military agency membership status,and education level(the lower the education level,the higher the smoking rates).With the exception of the downward trend in smoking behavior with increasing age among civilian employees,these results were all significant(P<0.005).Conclusions:This data analysis shows that smoking prevalence among personnel in the area of responsibility of the Federal Ministry of Defense is comparable to the current data from corresponding surveys of the German *** on gender,they generally show values that are slightly above those of the German *** well-known trend in the general population of decreasing smoking prevalence with increasing age is also seen in this ***,there are considerable differences in the smoking prevalence among individual subgroups(professional status,agency,gender,education level).The data show that particular young soldiers in the armed forces should be the target group for further preventive measures.

关键词： Prevention Smoking Military Health promotion

Atomistic simulation of tension deformation behavior in magnesium single crystal

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Acta Metallurgica Sinica(English Letters) 2010年第5期23卷 370-380页

作者： Yafang GUO Yuesheng WANG Honggang QI dirk STEGLICH Institute of Engineering Mechanics Beijing Jiaotong University Beijing 100044 China GKSS Research Centre Institute of Materials Research Materials Mechanics D-21502 Geesthacht Germany Graduate Institute of Ferrous Technology Pohang University of Science and Technology Pohang Gyeongbuk 790-784 Korea

The deformation behavior in magnesium single crystal under c-axis tension is investigated in a temperature range between 250 K and 570 K by molecular dynamics simulations. At a low temperature, twinning and shear bands are found to be the main deformation mechanisms. In particular, the {102} tension twins with the reorientation angle of about 90 °are observed in the simulations. The mechanisms of {102} twinning are illustrated by the simulated motion of atoms. Moreover, grain nucleation and growth are found to be accompanied with the {102} twinning. At temperatures above 450 K, the twin frequency decreases with increasing temperature. The {102} extension twin almost disappears at the temperature of 570 K. The non-basal slip plays an important role on the tensile deformation in magnesium single crystal at high temperatures.

关键词： Atomistic simulations Magnesium Twinning c-axis tension

A Comparative Study of the Local Heat Transfer Distributions Around Various Surface Mounted Obstacles

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Journal of Thermal Science 2014年第2期23卷 169-176页

作者： Robert Wyssmann dirk Ullmer Alexandros Terzis Peter Ott Group of Thermal Turbomachinery(GTT) cole Polytechnique Fédérale de Lausanne (EPFL)SCI-STI-POCH-1015LausanneSwitzerland

In many engineering applications,heat transfer enhancement techniques are of vital importance in order to ensure reliable thermal designs of convective heat transfer *** study examines experimentally the heat transfer characteristics on the base plate around various surface mounted *** convection coefficients are evaluated in the vicinity of each individual protruding body with great spatial resolution using the transient liquid crystal *** different obstacles of constant height-to-hydraulic diameter ratio(~1.3) are *** include:a cylinder,a square,a triangle,a diamond and a vortex generator of delta wing shape *** experiments were carried out over a range of freestream Reynolds numbers,based on the hydraulic diameter of each obstacle,varying from 4,000 to 13,*** results indicate a negligible effect of the flow speed on the heat transfer topological structure and a considerable effect of the obstacle geometry on the level and distribution of heat transfer enhancement.

关键词： surface obstacles heat transfer enhancement transient liquid crystal technique

Plant genetics enters the nano age?

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Journal of Integrative Plant Biology 2018年第6期60卷 446-447页

作者： dirk joldersma zhongchi liu department of cell biology and molecular genetics university of marylandCollege ParkM D 20817USA

Plant transformation has for many years relied on agrobacterium infection or biolistic particle delivery. However, these two methods are limited to model plant systems or a small number of crop species. This commentary highlights recent developments in the nanoparticle-mediated transformation that havethe potential to revolutionize how plants are trans- formed.

关键词： William J. Lucas University of California Davis USA

Characterization of colloidal arsenic at two abandoned gold mine sites in Nova Scotia, Canada, using asymmetric flow-field flow fractionation-inductively coupled plasma mass spectrometry

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Journal of Environmental Sciences 2016年第11期28卷 189-196页

作者： Kathryn J Tindale Pritesh J Patel dirk Wallschlager Environmental and Life Sciences Graduate Program School of the Environment Department of Chemistry and Water Quality Centre Trent University Peterborough ON K9L 0G2 Canada Ore Pros Inc Beamsville ON LOR 1B2 Canada

Asymmetric flow-field flow fractionation-inductively-coupled plasma-mass spectrometry was used to determine whether colloidal arsenic（As） exists in soil pore water and soil extract samples at two arsenic-contaminated abandoned gold mines（Montague and Goldenville, Nova Scotia）. Colloidal arsenic was found in 12 out of the 80 collected samples（= 15%）, and was primarily associated with iron（Fe） in the encountered colloids. The molar Fe/As ratios indicate that the colloids in some samples appeared to be discrete iron–arsenic minerals, whereas in other samples, they were more consistent with As-rich iron（oxy）hydroxides. Up to three discrete size fractions of colloidal As were encountered in the samples, with mean colloid diameters between 6 and 14 nm. The pore water samples only contained one size fraction of As-bearing colloids（around 6 nm diameter）, while larger As-bearing colloids were only encountered in soil extracts.

关键词： Arsenic Colloids Gold mine tailings ICP-MS Nova Scotia Nanoparticles

Frequency domain based DC fault analysis for bipolar HVDC grids

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Journal of Modern Power Systems and Clean Energy 2017年第4期5卷 548-559页

作者： Mian WANG Jef BEERTEN dirk Van HERTEM EnergyVille/Electa Research Group Electrical Engineering Department ESATKU Leuven3001 HeverleeBelgium

This paper proposes a frequency domain based methodology to analyse the influence of High Voltage Direct Current(HVDC) configurations and system parameters on the travelling wave behaviour during a DC fault. The method allows us to gain deeper understanding of these influencing parameters. In the literature, the majority of DC protection algorithms essentially use thefirst travelling waves initiated by a DC fault for fault discrimination due to the stringent time constraint in DC grid protection. However, most protection algorithms up to now have been designed based on extensive time domain simulations using one specific test system. Therefore, general applicability or adaptability to different configurations and system changes is not by default ensured, and it is difficult to gain in-depth understanding of the influencing parameters through time domain simulations. In order to analyse the first travelling wave for meshed HVDC grids, voltage and current wave transfer functions with respect to the incident voltage wave are derived adopting Laplace domain based component models. The step responses obtained from the voltage transfer functions are validated by comparison against simulations using a detailed model implemented in PSCADTM. Then, the influences of system parameters such as the number of parallel branches, HVDC grid configurations and groundings on the first travelling wave are investigated by analysing the voltage and current transfer functions.

关键词： HVDC grids DC grid protection Travelling wave Frequency domain analysis Transfer function

Predicting prognosis in colorectal liver metastases

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Hepatobiliary Surgery and Nutrition 2019年第6期8卷 643-645页

作者： dirk Grünhagen Erasmus MC Cancer Institute RotterdamThe Netherlands

Liver surgeons treating colorectal liver metastases(CRLM)are on the verge of fascinating *** one hand,there is a trend towards minimally invasive,or percutaneous,approaches of liver treatment,whereas on the other hand reports on maximally invasive surgery have come out that claim survival benefit for CRLM patients if treated *** order to choose between these different treatment philosophies,the surgeon,and equally importantly the patient,need *** that will tell whether the proposed treatment option will indeed be of benefit for the patient sitting in clinic in front of you.

关键词： colorectal metastases Liver

Bean yellow disorder virus： Parameters of transmission by Bemisia tabaci and host plant range

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Insect Science 2011年第1期18卷 50-56页

作者： German Martin Isabel Maria Cuadrado dirk Janssen Instituto Andaluz de Investigacion y Formacion Agraria y Pesquera Centro La Mojonera Almeria Spain

Bean yellow disorder virus （BnYDV） was recently identified as the first crinivirus （family Closteroviridae） that infects members of the family Leguminosae. It was first observed during the autumn of 2003, causing heavy losses in French bean （Phaseolus vulgaris L.） grown commercially in Spain. The virus is transmitted by the sweetpotato whitefly, Bemisia tabaci （Hemiptera： Aleyrodidae） Q-biotype, and disease symptoms resemble nutritional disorders consisting of interveinal mottling and yellowing in leaves, combined with stiffness or brittleness, and are typically produced on the middle to lower parts of the plant. Transmission experiments showed that 50% and 100% of B. tabaci adults acquired the virus after a feeding period of 3 and 7 h, respectively. Viruliferous whiteflies infected 66% and 100% ofP. vulgaris plants after a feeding period of 12 and 24 h, respectively. The transmission efficiency of single whiteflies was 37% and persistence of BnYDV in the vector lasted up to 2 weeks with a half-life of 9 days. BnYDV was transmitted to P. vulgaris, Pisum sativum L., Lens culinaris Medik., and Vicia faba L., but not to Vigna unguiculata L., Glycine max （L.） Merr., Cicer arietum L., and to crop species belonging to families of the Solanaceae and Cucurbitaceae. No virus was detected in field samples collected from 30 different species from Boraginaceae, Asteraceae, Geraniaceae, Lamiaceae, Leguminosae, Malvaceae, Scrophulariaceae, Thymelaeaceae and Verbenaceae. The restricted host range and efficient management of crops regarding whitefly infestation may be key elements in the control of BnYDV.

关键词： bean Closteroviridae Crinivirus disease vector whiteflies