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Selective Suspension in Aqueous Sodium dodecyl Sulfate According to Electronic Structure Type Allows Simple Separation of Metallic from Semiconducting Single-Walled Carbon Nanotubes

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Nano Research 2009年第8期2卷 599-606页

作者： Kai Moshammer Frank Hennrich Manfred M.Kappes Forschungszentrum karlsruhe Institut für NanotechnologieD-76021 KarlsruheGermany Institut für Physikalische Chemie Universität KarlsruheD-76128 KarlsruheGermany

Both density gradient centrifugation and gel electrophoresis have been reported to allow high throughput separation of metallic from semiconducting single-walled carbon nanotubes(SWNTs)when using aqueous sodium dodecyl sulphate(SdS)*** show here that both methods rely on an initial dispersion-by-sonication step,which is already selective with respect to electronic structure *** corresponding aqueous SdS“starting”suspensions obtained after sonication and purifi cation by simple centrifugation(70,000 g,1 h)contain semiconducting SWNTs primarily in the form of small bundles whereas metallic SWNTs are predominantly suspended as individual *** gradient centrifugation then separates the bundles from the individual tubes on the basis of differences in their overall buoyant *** electrophoresis separates the longer bundles from the shorter individual tubes on the basis of their different *** also demonstrate that such starting suspensions can be fractionated according to electronic structure type by even simpler techniques such as size exclusion chromatography or gel fi ltration,thus opening the way for simple scale-up.

关键词： Single-walled carbon nanotubes metallic–semiconducting separation electrophoresis density gradient centrifugation size exclusion chromatography

Thermal-Hydraulic System Study of the Helium Cooled Pebble Bed (HCPB) Test Blanket Module (TBM) for ITER Using System Code RELAP5

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Plasma Science and Technology 2005年第2期7卷 2753-2757页

作者：金雪舟 R.Meyder Forschungszentrum karlsruhe Institute for Reactor Safety P.O. Box 3640D-76021 KarlsruheGermany

The HCPB concept has been a European dEMO reference concept for nearly one decade. detailed thermal-hydraulic study on the control behavior of the whole system is one of the important parts of this development. The thermal-hydraulic effect of the TBM-combined cooling circuit during a cyclic operation in ITER has been studied using the system code RELAP5. The RELAP5 is based on an one-dimensional, transient two-fluid model for the flow of a two-phase steam-water mixture that can contain noncondensable components like Helium. The RELAP5models are modified to take the cyclic operation of the circulator, heat, exchanger, bypass, valves etc in to account. A sequence of operational phases is investigated, starting from the cold state through the heating phase that brings the system to a stand-by condition, followed by typical power cycles applied in ITER. The results show that the implemented control mechanisms keep the inlet temperature to the TBM and the total mass flow rate at the required values through all phases.

关键词： test blanket module helium cooled pebble bed RELAP5 cooling system

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

Imaging Electronic Structure of Carbon Nanotubes by Voltage-Contrast Scanning Electron Microscopy

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Nano Research 2008年第4期1卷 321-332页

作者： Aravind Vijayaraghavan Sabine Blatt Christoph Marquardt Simone dehm Raghav Wahi Frank Hennrich Ralph Krupke Institut für Nanotechnologie Forschungszentrum KarlsruheD-76344 Eggenstein-LeopoldshafenGermany Physikalisches Institut Universität KarlsruheD-76021 KarlsruheGermany

We introduce voltage-contrast scanning electron microscopy(VC-SEM)for visual characterization of the electronic properties of single-walled carbon ***-SEM involves tuning the electronic band structure and imaging the potential profi le along the length of the *** resultant secondary electron contrast allows to distinguish between metallic and semiconducting carbon nanotubes and to follow the switching of semiconducting nanotube devices,as confi rmed by in situ electrical transport *** demonstrate that high-density arrays of individual nanotube devices can be rapidly and simultaneously characterized.A leakage current model in combination with fi nite element simulations of the device electrostatics is presented in order to explain the observed contrast evolution of the nanotube and surface *** work serves to fi ll a void in electronic characterization of molecular device architectures.

关键词： Carbon nanotubes electronic properties voltage-contrast scanning electron microscopy electrostatics

Principles of carbon nanotube dielectrophoresis

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Nano Research 2021年第7期14卷 2188-2206页

作者： Wenshan Li Frank Hennrich Benjamin S.Flavel Simone dehm Manfred Kappes Ralph Krupke Institute of Nanotechnology Karlsruhe Institute of TechnologyKarlsruhe 76021Germany Institute of Physical Chemistry Karlsruhe Institute of TechnologyKarlsruhe 76021Germany Institute of Materials Science Technische Universität DarmstadtDarmstadt 64287Germany Institute for Quantum Materials and Technologies Karlsruhe Institute of TechnologyKarlsruhe 76021Germany School of Mechanical Engineering Shanghai Jiao Tong UniversityNo.800 Dongchuan RoadShanghai 200240Chin

dielectrophoresis(dEP)describes the motion of suspended objects when exposed to an inhomogeneous electric *** has been successful as a method for parallel and site-selective assembling of nanotubes from a dispersion into a sophisticated device *** have conducted extensive works to understand the dEP of nanotubes in aqueous ionic surfactant ***,only recently,dEP was applied to polymer-wrapped single-walled carbon nanotubes(SWCNTs)in organic solvents due to the availability of ultra-pure SWCNT *** this paper,the focus is on the difference between the dEP in aqueous and organic *** starts with an introduction into the dEP of carbon nanotubes(CNT-dEP)to provide a comprehensive,in-depth theoretical background before discussing in detail the experimental procedures and *** academic interests,this work focuses on the CNT-dEP deposition scheme,discusses the importance of the electrical double layer,and employs finite element simulations to optimize CNT-dEP deposition condition with respect to the experimental *** important outcome is an understanding of why dEP in organic solvents allows for the deposition and alignment of SWCNTs in low-frequency and even static electric fields,and why the response of semiconducting SWCNTs(s-SWCNTs)is strongly enhanced in non-conducting,weakly polarizable *** to further improve CNT-dEP for s-SWCNT-relevant applications are given as ***,this work should serve as a practical guideline to select the appropriate setting for effective CNT dEPs.

关键词： single-walled carbon nanotubes hydrodynamics assembly deposition alignment polarizability dielectrophoresis

Modeling of Long-Range Intra- and Inter-Species Charged Particle Collisions for PIC Simulations

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Communications in Computational Physics 2010年第5期7卷 877-903页

作者： d.d’Andrea C.-d.Munz R.Schneider Forschungszentrum karlsruhe-in der Helmholtz-Gemeinschaft Institut fur Kern-und EnergietechnikPF 3640D-76021 KarlsruheGermany Institut fur Aerodynamik und Gasdynamik Universitat StuttgartPfaffenwaldring 21D-70550 StuttgartGermany Forschungszentrum karlsruhe-in der Helmholtz-Gemeinschaft Institut fur Hochleistungsimpuls und MikrowellentechnikPF 3640D-76021 KarlsruheGermany

In this paper we present the modelling of elastic intra-species electron-electron and inter-species electron-ion scattering in a plasma on the basis of the FokkerPlanck collision *** into account the equivalence of this operator with a stochastic differential equation,we propose a Particle-in-Cell based approach for the numerical solution of the Fokker-Planck collision *** we will see,the introduced numerical concept allows the simulation of the collisional relaxation process in a fully self-consistent fashion.

关键词： Coulomb collisions in plasmas collisional relaxation Fokker-Planck equation stochastic differential equation particle-in-cell method

The Top of the Biomimetic Triangle

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Journal of Bionic Engineering 2008年第2期5卷 91-94页

作者： Andrei P. Sommer dan Zhu Matthias Wiora Hans-Joerg Fecht Institute of Micro and Nanomaterials University of Ulm Ulm 89081 Germany Institute for Nanotechnology Forschungszentrum Karlsruhe Karlsruhe 76021 Germany

There is increasing observational evidence indicating that crystalline interfacial water layers play a central role in evolution and biology. For instance in cellular recognition processes, in particular during first contact events, where cells decide upon survival or entering apoptosis. Understanding water layers is thus crucial in biomedical engineering, specifically in the design of biomaterials inspired by biomimetic principles. Whereas there is ample experimental evidence for crystalline interfacial water layers on surfaces in air, their subaquatic presence could not be verified directly, so far. Analysing a polarity dependent asym- metry in the surface conductivity on hydrogenated nanocrystalline diamond, we show that crystalline interfacial water layers persist subaquatically. Nanoscopic interfacial water layers with an order different from that of bulk water have been identified at room temperature on both hydrophilic and hydrophobic model surfaces - in air and subaquatically. Their generalization and systematic inclusion into the catalogue of physical and chemical determinants of biocompatibility complete the biomimetic triangle.

关键词： biomimetic triangle crystalline interfacial water layers nanobionics diamond

Seed selections for crystallization of calcium phosphate for phosphorus recovery

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Journal of Environmental Sciences 2007年第5期19卷 591-595页

作者： SONG Yong-hui dietfried dONNERT Ute BERG Peter G. WEIdLER Rolf NUEESCH Chinese Research Academy of Environmental Sciences Beijing 100012 China Institute for Technical Chemistry-Section of Water- and Geo-technology （ITC-WGT） Research Centre of Karlsruhe Karlsruhe D-76021 Germany

Seed induces and promotes the crystallization of calcium phosphate, and acts as carrier of the recovered phosphorus （P）. In order to select suitable seed for P recovery from wastewater, three seeds including Apatite （AP）, Juraperle （JP） and phosphate-modified Juraperle （M-JP） were tested and compared. Batch and fixed-bed column experiments of seeded crystallization of calcium phosphate were undertaken by using synthetic wastewater with 10 mg/L P phosphate. It shows that AP has bad enduring property in the crystallization process, while JP has better performance for multiple uses, and M-JP is a hopeful seed for P recovery by crystallization of calcium phosphate.

关键词： crystallization seed phosphorus recovery Juraperle Apatite

Numerical Noise Prediction in Fluid Machinery

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Journal of Thermal Science 2005年第3期14卷 230-235,248页

作者： Iris PANTLE Franco MAGAGNATO Martin GABI department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe

Numerical methods successively became important in the design and optimization of fluid machinery. However, as noise emission is considered, one can hardly find standardized prediction methods combining flow and acoustical optimization. Several numerical field methods for sound calculations have been developed. due to the complexity of the considered flow, approaches must be chosen to avoid exhaustive computing. In this contribution the noise of a simple propeller is investigated. The configurations of the calculations comply with an existing experimental setup chosen for evaluation. The used in-house CFd solver SPARC contains an acoustic module based on Ffowcs Williams-Hawkings Acoustic Analogy. From the flow results of the time dependent Large Eddy Simulation the time dependent acoustic sources are extracted and given to the acoustic module where relevant sound pressure levels are calculated. The difficulties, which arise while proceeding from open to closed rotors and from gas to liquid are discussed.

关键词： numerical noise prediction fluid machinery computational aero-acoustics large eddy simulation