Search results for "fusion"
showing 10 items of 4513 documents
Comparison of 2D versus 3D diffusion analysis at Nanowire Electrodes: Finite element analysis and experimental study
2021
In electroanalysis, finite element simulations of electrochemical processes occurring at electrodes are used to provide key insight into experimental design in relation to diffusion profiles and expected currents. The diffusion domain approach (DDA) offers a means of reducing a three dimensional design to two dimensions to ease computational demands. However, the DDA approach can be limited when basic assumptions, for example that all electrodes in an array are equivalent, are incorrect. Consequently, to get a more realistic view of molecular diffusion to nanoelectrodes, it is necessary to undertake simulations in 3D. In this work, two and three dimensional models of electrodes comprising o…
Characteristics of the polymer transport in ratchet systems
2010
Molecules with complex internal structure in time-dependent periodic potentials are studied by using short Rubinstein-Duke model polymers as an example. We extend our earlier work on transport in stochastically varying potentials to cover also deterministic potential switching mechanisms, energetic efficiency and non-uniform charge distributions. We also use currents in the non-equilibrium steady state to identify the dominating mechanisms that lead to polymer transportation and analyze the evolution of the macroscopic state (e.g., total and head-to-head lengths) of the polymers. Several numerical methods are used to solve the master equations and nonlinear optimization problems. The domina…
Determination of limiting current density and current efficiency in electrodialysis units
2018
Abstract A crucial parameter for the design and operation of electrodialysis (ED) units is the limiting current density (LCD). This is often identified with the diffusion-limited current density, which corresponds to the complete solute depletion in the layer adjacent to the membrane. Current-voltage curves obtained from measurements with electrodes in contact with the solution (i.e. without membranes) are consistent with this interpretation and exhibit a horizontal plateau identifying LCD. However, real ED systems show more complex behaviours, with a reduced-slope tract instead of a plateau and a third region in which the current increases more markedly (overlimiting current). The phenomen…
Gelchromatographische refraktionierung, molekulargewichtsabhängigkeit der axialen dispersionsfunktion
1979
The knowledge of axial dispersion is necessary for the determination of molecular weight distributions from gel permeation chromatograms. This work deals with the determination of the axial dispersion function and its dependence on the molecular weight using refractionation method. The results of a number of fractionated and unfractionated samples of polystyrene reveal that peak dispersion in GPC arises mainly from diffusion in the stationary phase on the basis of the theoretical expression proposed by Kubin.
The design of the DONES lithium target system
2019
Abstract In the framework of the EU fusion roadmap implementing activities, an accelerator-based Li(d,xn) neutron source called DONES (Demo-Oriented early NEutron Source) is being designed within the EUROfusion Work Package Early Neutron Source as an essential irradiation facility for testing candidate materials for DEMO reactor and future fusion power plants. DONES will employ a high speed liquid lithium jet struck by a 125 mA, 40 MeV deuteron beam to generate the intense neutron flux used to irradiate the material samples up to the desired level of displacement damage (˜10 dpa/fpy for iron in 0.3 l) and He production rates (˜10-13 appm He/dpa). In order to rapidly achieve a sound and stab…
Hyperspectral imaging in perfusion and wound diagnostics – methods and algorithms for the determination of tissue parameters
2018
Abstract Blood perfusion is the supply of tissue with blood, and oxygen is a key factor in the field of minor and major wound healing. Reduced perfusion of a wound bed or transplant often causes various complications. Reliable methods for an objective evaluation of perfusion status are still lacking, and insufficient perfusion may remain undiscovered, resulting in chronic processes and failing transplants. Hyperspectral imaging (HSI) represents a novel method with increasing importance for clinical practice. Therefore, methods, software and algorithms for a new HSI system are presented which can be used to observe tissue oxygenation and other parameters that are of importance in supervising…
Buildup and structure of theInSe∕Ptinterface studied by angle-resolved photoemission and x-ray absorption spectroscopy
2006
The atomic structure and the electronic nature of the $\mathrm{In}\mathrm{Se}∕\mathrm{Pt}$ interface have been studied by x-ray absorption spectroscopy and angle-resolved photoemission, respectively. By these measurements, it has been found that Pt atoms equally incorporate into two trigonal-prismatic intralayer positions existing within the InSe layer, although, at low Pt coverage, Pt atoms seem to prefer one of these sites, where they have a lower interaction with Se atoms. The atomic structure of the $\mathrm{In}\mathrm{Se}∕\mathrm{Pt}$ interface appears to determine its electronic behavior as Pt deposition increases. At initial stages of Pt diffusion, isolated Pt atoms act as a surface …
A structural comparison of halloysite nanotubes of different origin by Small-Angle Neutron Scattering (SANS) and Electric Birefringence
2018
The structure of halloysite nanotubes (Hal) from different mines was investigated by Small-Angle Neutron Scattering (SANS) and Electric Birefringence (EBR) experiments. The analysis of the SANS curves allowed us to correlate the sizes and polydispersity and the specific surfaces (obtained by a Porod analysis of the SANS data) of the nanotubes with their specific geological setting. Contrast matching measurements were performed on patch Hal (from Western Australia) in order to determine their experimental scattering length density for a more precise analysis. Further characterization of the mesoscopic structure of Hal was carried out by Electric Birefringence (EBR), which allowed to study th…
Polar Localization of a Tripartite Complex of the Two-Component System DcuS/DcuR and the Transporter DctA in Escherichia coli Depends on the Sensor K…
2014
The C4-dicarboxylate responsive sensor kinase DcuS of the DcuS/DcuR two-component system of E. coli is membrane-bound and reveals a polar localization. DcuS uses the C4-dicarboxylate transporter DctA as a co-regulator forming DctA/DcuS sensor units. Here it is shown by fluorescence microscopy with fusion proteins that DcuS has a dynamic and preferential polar localization, even at very low expression levels. Single assemblies of DcuS had high mobility in fast time lapse acquisitions, and fast recovery in FRAP experiments, excluding polar accumulation due to aggregation. DctA and DcuR fused to derivatives of the YFP protein are dispersed in the membrane or in the cytosol, respectively, when …
Computational Modeling of Protein Dynamics in Eukaryotic Cells
2012
Proteins have important functions inside the cell, traveling diffusively or being actively transported to various cellular sites where their activity is needed. Protein motion in the cellular environment is therefore an important topic to understand. However, the cell provides a very complex environment for that motion, which poses problems especially for any modeling effort designed to interpret experimentally observed features. So as to gain a realistic picture of protein dynamics inside the cell, we have recently introduced advanced numerical methods for describing that dynamics [1]. The starting point is an accurate numerical duplicate of the cell determined by LSCM, which can be used a…