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Coulomb drag between in-plane graphene double ribbons and the impact of the dielectric constant

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Nano Research 2013年第12期6卷 897-905页

作者： Hongyan Chen joerg Appenzeller Electrical and Computer Engineering Department Purdue University West Lafayette IN 47907 USA

With recent developments in the search for novel device ideas, understanding electron-electron interaction in low dimensional systems is of particular interest. Coulomb drag measurements can provide critical insights in this context. In this article, we present a novel planar graphene double ribbon structure that shows for the first time that Coulomb drag is observable in two adjacent monolayer ribbons in the same plane at room temperature. Moreover, our planar devices enable experimentally study of the impact of the dielectric constant on Coulomb drag which is difficult to explore in the typically used double layer graphene structures. Our experimental findings indicate in particular that the drag resistance is proportional to the dielectric constant （~） and does not, as recently reported, show an increasing trend of interaction strength for small C-values. In fact, we find that the drag resistance follows approximately an ~l.2-dependence. The exponent of ＂1.2＂ is consistent with the theory considering the carrier concentration in our samples, and positions our results in between the weak and strong coupling limits.

关键词： Coulomb drag graphene ribbon dielectric scattering electron-electroninteractions

Sequence diversity of hepatitis C virus: Implications for immune control and therapy

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World Journal of Gastroenterology 2007年第36期13卷 4807-4817页

作者： joerg Timm Michael Roggendorf University of Essen Instituteof Virology Essen 45122 Germany

With approximately 3% of the world’s population (170 million people) infected with the hepatitis C virus (HCV), the WHO has declared HCV a global health problem. Upon acute infection about 50%-80% of subjects develop chronic hepatitis with viral persistence being at risk to develop liver cirrhosis and hepatocellular carcinoma. One characteristic of HCV is its enormous sequence diversity, which represents a significant hurdle to the development of both effective vaccines as well as to novel therapeutic interventions. Due to a polymerase that lacks a proofreading function HCV presents with a high rate of evolution, which enables rapid adaptation to a new environment including an activated immune system upon acute infection. Similarly, novel drugs designed to specifically inhibit viral proteins will face the potential problem of rapid selection of drug resistance mutations. This review focuses on the sequence diversity of HCV, the driving forces of evolution and the impact on immune control and treatment response. An important feature of any therapeutic or prophylactic intervention will be an efficient attack of a structurally or functionally important region in the viral protein. The understanding of the driving forces, but also the limits of viral evolution, will be fundamental for the design of novel therapies.

关键词： Hepatitis C Virus Evolution Escape Drug resistance Selection

PARALLEL HIERARCHICAL MATRIX PRECONDITIONERS FOR THE CURL-CURL OPERATOR

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Journal of Computational Mathematics 2009年第5期27卷 624-641页

作者： Mario Bebendorf joerg Ostrowski Institut fur Numerische Simulation Universitat BonnWegelerstrasse 653115 BonnGermany ABB Switzerland Ltd Corporate ResearchSegelhofstrasse 1 K/P.O.BoxCH-5405 Baden 5 Dattwil

This paper deals with the preconditioning of the curl-curl operator. We use H（curl）- conforming finite elements for the discretization of our corresponding magnetostatic model problem. Jumps in the material parameters influence the condition of the problem. We will demonstrate by theoretical estimates and numerical experiments that hierarchical matrices are well suited to construct efficient parallel preconditioners for the fast and robust iterative solution of such problems.

关键词： Computational electromagnetism Preconditioners Hierarchical matrices Parallelization.

Influence of rotating wakes on separation in turbine exhaust diffusers

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Journal of Thermal Science 2008年第1期17卷 42-49页

作者： Olaf Sieker joerg R.Seume Department of Turbomachinery and Fluid Dynamics Leibniz University HannoverAppelstr.9DE-30167 HannoverGermany Dipl.-Ing. Department of Turbomachinery and Fluid Dynamics Leibniz University HannoverAppelstr.9DE-30167 HannoverGermany

Highly efficient turbine exhaust diffuser cannot be designed without taking into account the unsteady interactions with the last rotating row of the turbine. Former investigations described in the literature show a very high potential compared to that of other parts of turbomachines for improving the diffuser. A scale model of a typical gas turbine exhaust diffuser is investigated experimentally. To investigate the influence of rotating wakes, measurements without a spoke wheel as well as measurements with a variable-speed rotating cylindrical spoke wheel with 2 mm- or 10 mm-spokes simulating turbine rotor wakes were made. Miniaturized 3-hole pneumatic probes as well as a 2D-Laser-Doppler-Velocimeter （LDV） were used to investigate velocity profiles. 122 static pressure tapings were used to measure several axial and circumferential static pressure distributions. Without a spoke-wheel the annular diffuser separates at the shroud for all swirl configurations. For the measurements with the 2 mm spoke wheel, the separating diffuser was unstable while keeping the test rig operating parameters constant. For a non-rotating 10 mm spoke wheel and at rotational speeds less than 1,000 rpm, the annular diffuser separated at the shroud. Increasing the rotational speed of the 10mm spoke wheel, flow did not separate at the shroud and much higher pressure recovery than without spoke wheel has achieved.

关键词： turbine exhaust diffuser rotating wakes separation LDV

SARS-CoV-2 nanobodies 2.0

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Signal Transduction and Targeted Therapy 2021年第6期6卷 1640-1642页

作者： Fabien Labroussaa joerg Jores Institute of Veterinary Bacteriology Department of Infectious Diseases and PathobiologyUniversity of BernBernSwitzerland

In a recent study published in Science,Koenig et al.1 reported on rationally engineered biparatopic nanobodies targeting the receptor-binding domain(RBD)of the spike protein that not only efficiently neutralize SARS-CoV-2,but additionally suppress mutational *** growth,increased travel and climate change foster epidemic and pandemic threats by(re)emerging viruses.

关键词： al. travel rational

Interaction between Struts and Swirl Flow in Gas Turbine Exhaust Diffusers

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Journal of Thermal Science 2005年第4期14卷 314-320页

作者： Roman Z.PIETRAsch joerg R.SEUME Turbomachinery Laboratory University of Hannover Appelstr. 9 D-31678 Hannover Germany

The increasing use of gas turbines in combined cycle power plants together with the high amount of kinetic energy in modem gas turbine exhaust flows focuses attention on the design of gas turbine diffusers as the connecting part between the Brayton/Joule and the Rankine parts of the combined cycle. A scale model of a typical gas turbine exhaust diffuser is investigated experimentally. The test rig consists of a radial type, variable swirl generator which provides the exhaust flow corresponding to different gas turbine operating conditions. Static pressure measurements are carried out along the outer diffuser walls and along the hub of the annular part and along the centerline of the conical diffuser. Velocity distributions at several axial positions in the annular and conical diffuser have been measured using a Laser Doppler Velocimeter （LDV）. Pressure recovery coefficients and velocity profiles are depicted as a function of diffuser length for several combinations of swirl strength, tip flow and strut geometries. The diffuser without struts achieved a higher pressure recovery than the diffuser with struts at all swirl angle settings. The diffuser with cylindrical struts achieved a higher pressure recovery than the diffuser with profiled struts at all swirl angle ***. Inlet flows with swirl angles over 18° affected the pressure recovery negatively for all strut configurations.

关键词： gas turbine exhaust diffuser swirl struts pressure recovery coefficient.

Ternary Diffusion Coefficients of 1-Hexanol-Hexane-Toluene and 1-Propanol-Water-Ethylene Glycol by Taylor Dispersion Method

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Tsinghua Science and Technology 2005年第5期10卷 523-528页

作者：任钟旗费维扬 Hans-joerg Bart State Key Laboratory of Solvent Extraction Department of Chemical Engineering Tsinghua University Beijing 100084 China Institute of Chemical Engineering University of Kaiserslautern Kaiserslautern 67653 Germany

The Taylor dispersion method was used to measure diffusion coefficients of three-component liquid systems. An improved constrained nonlinear least-square method was used to evaluate the ternary diffusion coefficients directly by fitting the mathematical solutions of the dispersion equation to eluted solute peaks detected using a differential refractometer. Diffusion coefficients of the three-component system of acetone-benzene-CCl4, determined at 25℃, were used to test the procedure. The measured diffusion coefficients were compared with values obtained by optical interferometry and the diaphragm cell method. Ternary diffusion coefficients are also determinated for solutions of 1-hexanol-hexane-toluene and 1-propanol- water-ethylene glycol at 25℃, with an accuracy of approximately 0.05 m^2·s^- 1.

关键词： Taylor dispersion method ternary diffusion coefficient constrained nonlinear least-squared method Fick law

Bottom-up synthesis of ultrathin straight platinum nanowires： Electric field impact

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Nano Research 2013年第5期6卷 303-311页

作者： Alexander Nerowski joerg Opitz Larysa Baraban Gianaurelio Cuniberti Institute far Materials Science and Max Bergmann Center of Biomaterials Dresden University of Technology Dresden 01062 Germany Fraunhofer Institute for Non-Destructive Testing Dresden 01109 Germany Division o fiT Convergence Engineering POSTECH Pohang 790-784 Republic of Korea

We present a study of the electric field effect on electrochemically grown ultrathin, straight platinum nanowires with minimum diameter of 15 nm and length in the micrometer range, synthesized on a silicon oxide substrate between metal electrodes in H2PtC16 solution. The influence of the concentration of the platinum- containing acid and the frequency of the applied voltage on the diameter of the nanowires is discussed with a corresponding theoretical analysis. We demonstrate for the first time that the electric field profile, provided by the specific geometry of the metal electrodes, dramatically influences the growth and morphology of the nanowires. Finally, we provide guidelines for the controlled fabrication and contacting of straight, ultrathin metal wires, eliminating branching and dendritic growth, which is one of the main shortcomings of the current bottom-up nanotechnology. The proposed concept of self-assembly of thin nanowires, influenced by the electric field, potentially represents a new route for guided nanocontacting via smart design of the electrode geometry. The possible applications reach from nanoelectronics to gas sensors and biosensors.

关键词： bottom-up growth directed electrochemicalnanowire assembly(DENA) metal nanowires nanostructuring nanoelectronics local electric field

Body Building on Diamonds

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Journal of Bionic Engineering 2009年第1期6卷 14-17页

作者： Andrei P. Sommer Tim scharnweber Hans-joerg Fecht Institute of Micro and Nanomaterials University of UlmUlm 89081Germany Institute for Biological Interfaces Research Center KarlsruheKarlsruhe 76021Germany Institute for Nanotechnology Research Center Karlsruhe Karlsruhe 76021Germany

Whereas conservative therapies aim to stall the advance of disease,regenerative medicine strives to reverse *** capacity of most tissues to regenerate derives from stem cells,but there are a number of barriers which have to be circumvented before it will be possible to use stem-cell-based *** therapies,however,are expected to improve human health enormously, and knowledge gained from studying stem cells in culture and in model organisms is now laying the groundwork for a new era of regenerative *** of the most prominent methods to study stem cell differentiation is to let them to form embryoid *** favourable conditions any stem cell line will form embryoid ***,the mechanism of the formation of embryoid bodies is not very well understood,and to produce them in the laboratory is in no way trivial-an important technical barrier in stem cell ***,the embryoid body cultivation step has been successfully circumvented for the derivation of osteogenic cultures of embryonic stem *** we report on a simple and reusable system to cultivate embryoid bodies in extremely short *** method is inspired by the principles that lead to the establishment of the biomimetic triangle.

关键词： biomimetic triangle stem cells embryoid bodies nanobionics nanocrystalline diamond