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Grasynski K.,Institute of Physical Chemistry of Combustion
PESC Record - IEEE Annual Power Electronics Specialists Conference | Year: 2015

For several years the German Ministry of Research and Technology (BMFT) sponsored investigations to realize large communication satellites, and to develop hardware of special critical components. The developments in the field of energy supply were a main effort. Power conditioning systems up to 10 kW are required. On principle it is possible to realize power conditioning for this large power range on the basis of DC-systems. But there rises problems relating to parts and weight closely associated with the thermal control system. To find a better solution several firms in Germany (AEG-Telefunken, Dornier System AG, Siemens AG and Teldix GmbH) investigated power conditioning concepts with AC distribution in the frequency range of about 20 kHz. First results indicated that even with an AC-system it is not possible to find a fundamental solution of the above mentioned problems, AC-systems seem to present certain advantages, though. In this paper some results of the developments of power conditioning concepts for a high power communication satellite are discussed. It is shown that an AC-system with regulated sinusoidal mainbus voltage is flexible and suited for high power applications. But for special applications decentralized current resonance systems may be better suited due to their high efficiency. © 1977 IEEE. Source


Eshet H.,ETH Zurich | Khaliullin R.Z.,ETH Zurich | Kuhne T.D.,Institute of Physical Chemistry of Combustion | Kuhne T.D.,Johannes Gutenberg University Mainz | And 2 more authors.
Physical Review B - Condensed Matter and Materials Physics | Year: 2010

An interatomic potential for high-pressure high-temperature (HPHT) crystalline and liquid phases of sodium is created using a neural-network (NN) representation of the ab initio potential-energy surface. It is demonstrated that the NN potential provides an ab initio quality description of multiple properties of liquid sodium and bcc, fcc, and cI16 crystal phases in the P-T region up to 120 GPa and 1200 K. The unique combination of computational efficiency of the NN potential and its ability to reproduce quantitatively experimental properties of sodium in the wide P-T range enables molecular-dynamics simulations of physicochemical processes in HPHT sodium of unprecedented quality. © 2010 The American Physical Society. Source


De Jong D.H.,Zernike Institute for Advanced Materials | De Jong D.H.,Institute of Physical Chemistry of Combustion | Liguori N.,VU University Amsterdam | Van Den Berg T.,Zernike Institute for Advanced Materials | And 3 more authors.
Journal of Physical Chemistry B | Year: 2015

Electron transfers within and between protein complexes are core processes of the electron transport chains occurring in thylakoid (chloroplast), mitochondrial, and bacterial membranes. These electron transfers involve a number of cofactors. Here we describe the derivation of molecular mechanics parameters for the cofactors associated with the function of the photosystem II core complex: plastoquinone, plastoquinol, heme b, chlorophyll A, pheophytin, and β-carotene. Parameters were also obtained for ubiquinol and ubiquinone, related cofactors involved in the respiratory chain. Parameters were derived at both atomistic and coarse grain (CG) resolutions, compatible with the building blocks of the GROMOS united-atom and Martini CG force fields, respectively. Structural and thermodynamic properties of the cofactors were compared to experimental values when available. The topologies were further tested in molecular dynamics simulations of the cofactors in their physiological environment, e.g., either in a lipid membrane environment or in complex with the heme binding protein bacterioferritin. © 2015 American Chemical Society. Source


Saha S.,Institute of Physical Chemistry of Combustion | Fischer K.,Institute of Physical Chemistry of Combustion | Muthukumar M.,Institute of Physical Chemistry of Combustion | Muthukumar M.,University of Massachusetts Amherst | Schmidt M.,Institute of Physical Chemistry of Combustion
Macromolecules | Year: 2013

The apparent molar mass of a partially quaternized poly-2-vinylpyridines (degree of quaternization 4.3% < Q < 35%) in 1-propanol is measured by light scattering at low ionic strength (10-6 M < cs < 10-3 M) as a function of polyion repeat unit concentration (7 × 10-5 monomol/L < cm,p < 4 × 10 -2 monomol/L). No dialysis was applied prior to measurements. The apparent molar mass under "salt-free" conditions is smaller than the true molar mass by an order of magnitude, while approaching the true value at higher ionic strength. Concomitant data on the dependence of scattering intensity on scattering wave vector show that the dilute polyelectrolyte solutions are strongly correlated. A recent theory by Muthukumar for light scattering of dilute polyelectrolyte solutions, developed for correlated multicomponent systems, accounts for interchain electrostatic correlations and regularization of polymer charge by counterion binding isotherm. The experimental results on the relation between the apparent and true molar masses as a function of salt concentration are compared with the predictions of Muthukumar's counterion adsorption theory. Taking binding equilibrium constant as a single fitting parameter, this theory is demonstrated to describe the experimental data as long as the chains do not interact significantly. © 2013 American Chemical Society. Source


Reuter A.,Monash Institute of Pharmaceutical Sciences | Reuter A.,Max Planck Graduate Center | Reuter A.,Institute of Physical Chemistry of Combustion | Panozza S.E.,University of Melbourne | And 15 more authors.
Journal of Immunology | Year: 2015

Ab-targeted vaccination involves targeting a receptor of choice expressed by dendritic cells (DCs) with Ag-coupled Abs. Currently, there is little consensus as to which criteria determine receptor selection to ensure superior Ag presentation and immunity. In this study, we investigated parameters of DC receptor internalization and determined how they impact Ag presentation outcomes. First, using mixed bone marrow chimeras, we established that Ag-targeted, but not nontargeted, DCs are responsible for Ag presentation in settings of Ab-targeted vaccination in vivo. Next, we analyzed parameters of DEC205 (CD205), Clec9A, CD11c, CD11b, and CD40 endocytosis and obtained quantitative measurements of internalization speed, surface turnover, and delivered Ag load. Exploiting these parameters in MHC class I (MHC I) and MHC class II (MHC II) Ag presentation assays, we showed that receptor expression level, proportion of surface turnover, or speed of receptor internalization did not impact MHC I or MHC II Ag presentation efficiency. Furthermore, the Ag load delivered to DCs did not correlate with the efficiency of MHC I or MHC II Ag presentation. In contrast, targeting Ag to CD8+ or CD82 DCs enhanced MHC I or MHC II Ag presentation, respectively. Therefore, receptor expression levels, speed of internalization, and/or the amount of Ag delivered can be excluded as major determinants that dictate Ag presentation efficiency in setting of Ab-targeted vaccination. Copyright © 2015 by The American Association of Immunologists, Inc. Source

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