Physisorption of molecular oxygen on single-wall carbon nanotube bundles and graphite

We present a study on the kinetics of oxygen adsorption and desorption from single-wall carbon nanotube (SWNT) and highly oriented pyrolytic graphite (HOPG) samples. Thermal desorption spectra for SWNT samples show a broad desorption feature peaked at 62 K which is shifted to significantly higher temperature than the low-coverage desorption feature on HOPG. The low-coverage O2 binding energy on SWNT bundles, 18.5 kJ/mol, is 55% higher than that for adsorption on HOPG, 12.0 kJ/mol. In combination with molecular mechanics calculations we show that the observed binding energies for both systems can be attributed to van der Waals interactions, i.e. physisorption. The experiments provide no evidence for a more strongly bound chemisorbed species or for dissociative oxygen adsorption.Comment: 7 pages, 5 figures, 1 tabl

Magnetic excitations in a bond-centered stripe phase: Spin waves far from the semi-classical limit

Using a spin-only model, we compute spin excitation spectra in a bond-centered stripe state with long-range magnetic order. We employ a bond operator formalism, which naturally captures both dimerization and broken spin symmetry in a unified framework. At low energies, the spin excitations resemble spin waves, but at higher energies they are very similar to spin-1 excitations of isolated spin ladders. Our theory does well describe neutron scattering data [J. M. Tranquada et al., Nature 429, 534 (2004)] on LaBaCuO, pointing towards bond order in this material.Comment: 4 pages, 3 figs, of possible relevance to experiments reported in cond-mat/0401621; (v2) final version as publishe

Die Rolle der PML-Kernkörperchen bei der Regulation der MHC Klasse II-Expression

Die Regulation der Lokalisation von Genen im Zellkern ist ein wichtiges Transkriptions-Kontrollelement in Eukaryoten. Für Wirbeltierzellen konnte gezeigt werden, dass bestimmte Gene mit Kernkörperchen assoziieren, wodurch möglicherweise deren Transkriptionsaktivität moduliert wird. Promyelozytische Leukämie (PML)-Körperchen sind Multiproteinkomplexe in Wirbeltierzellkernen, deren Funktion noch nicht geklärt ist. Es ist bekannt, dass diese Körperchen spezifisch mit dem Gen-reichen major histocompatibility (MHC) Gencluster auf Chromosom 6 assoziieren. Diese Genregion enthält eine Vielzahl von Genen für die Immunantwort. Die Frage, ob PML-Proteine bzw. -Körperchen an der Regulation dieser Gene beteiligt sind, blieb bislang unbeantwortet. Aufbauend auf der Beobachtung, dass die Assoziationsrate zwischen PML Körperchen und dem MHC Klasse II-Genlokus spezifisch durch Interferon γ (IFNγ) erhöht wird, zeigt die vorliegende Arbeit, dass IFNγ ebenfalls zu einer Rekrutierung von Faktoren, die die Transkription von MHC II-Genen kontrollieren, an PML-Körperchen führt. Vier der 8 bekannten MHC II-Transkriptionsfaktoren (CIITA, RFXap, RFXb und NFYa) binden an PML-Körperchen. Der MHC Klasse II-Transaktivator (CIITA), der Hauptregulator der MHC II-Gene, wird spezifisch durch die PML-Isoform II an PML-Körperchen rekrutiert. IFNγ verlängert die PML II-vermittelte Anbindung von CIITA an PML-Körperchen, die Verweildauer beträgt mehrere Minuten. Die Senkung der PML-Proteinmenge führt (1) zu einer Verringerung der Transkription einiger, aber nicht aller MHC II-Gene, (2) zur Inhibition der MHC II-Expression auf der Oberfläche von Fibroblasten und (3) zur verringerten IFNγ-induzierten Expression des CIITA. Diese Beobachtungen zeigen, dass PML(-Körperchen) eine Funktion als Koaktivator bei der IFNγ-induzierten MHC II-Expression ausübt. Der zugrundeliegende Mechanismus basiert vermutlich auf der Assoziation der PML-Körperchen mit dem MHC II-Genlokus und der Regulation der CIITA-Menge

Do media data help to predict German industrial production?

Expectations form the basis of economic decisions of market participants in an uncertain world. Sentiment indicators reflect those expectations and thus have a proven track record for predicting economic variables. However, respondents of surveys perceive the world to a large extent with the help of media. So far, mainly very crude media information, such as word-count indices, has been used in the prediction of macroeconomic and financial variables. In this paper, we employ a rich data set provided by Media Tenor International, based on the sentiment analysis of all relevant media information in Germany from 2001 to 2014, whose results are transformed into several monthly indices. German industrial production is predicted in a real-time out-of-sample forecasting experiment using more than 17,000 models formed of all possible combinations with a maximum of 3 out of 48 macroeconomic, survey, and media indicators. It is demonstrated that media data are indispensable when it comes to the prediction of German industrial production both for individual models and as a part of combined forecasts. They increase reliability by improving accuracy and reducing instability of the forecasts, particularly during the recent global financial crisis

Do media data help to predict German industrial production?

In an uncertain world, decisions by market participants are based on expectations. Thus, sentiment indicators reflecting expectations are proven at predicting economic variables. However, survey respondents largely perceive the world through media reports. Typically, crude media information, like word-count indices, is used in the prediction of macroeconomic and financial variables. Here, we employ a rich data set provided by Media Tenor International, based on sentiment analysis of opinion-leading media in Germany from 2001 to 2014, transformed into several monthly indices. German industrial production is predicted in a real-time out-of-sample forecasting experiment using more than 17,000 models formed of all possible combinations with a maximum of 3 out of 48 macroeconomic, survey, and media indicators. Media data are indispensable for the prediction of German industrial production both for individual models and as a part of combined forecasts, particularly during the global financial crisis

Color-charge separation in trapped SU(3) fermionic atoms

Cold fermionic atoms with three different hyperfine states with SU(3) symmetry confined in one-dimensional optical lattices show color-charge separation, generalizing the conventional spin charge separation for interacting SU(2) fermions in one dimension. Through time-dependent DMRG simulations, we explore the features of this phenomenon for a generalized SU(3) Hubbard Hamiltonian. In our numerical simulations of finite size systems, we observe different velocities of the charge and color degrees of freedom when a Gaussian wave packet or a charge (color) density response to a local perturbation is evolved. The differences between attractive and repulsive interactions are explored and we note that neither a small anisotropy of the interaction, breaking the SU(3) symmetry, nor the filling impedes the basic observation of these effects

Staubabscheider in häuslichen Feuerungen

Sehr geehrte Damen und Herren, Biomasse, insbesondere Holz, ist im deutschen Wärmemarkt der mit großem Abstand wichtigste erneuerbare Energieträger. Insbesondere häusliche Holzfeuerungen erfreuen sich einer hohen Beliebtheit. Regionale Wertschöpfung und weitgehende CO2-Neutralität sind die positiven Seiten dieser Entwicklung. Dem gegenüber stehen, insbesondere bei Altanlagen, erhöhte Emissionen von Feinstaub und anderen gasförmigen Schadstoffen. Damit durch den zwingend notwendigen Ausbau der erneuerbaren Energien keine neuen Umweltbelastungen entstehen, wurden in den letzten Jahren die gesetzlichen Grenzwerte für die wichtigsten Schadstoffe stufenweise verringert. Viele moderne Feuerungen sind in der Lage, diese ohne weitere Maßnahmen einzuhalten. In einigen Marktsegmenten können jedoch Feinstaubabscheider eine interessante Möglichkeit darstellen, die geforderten Grenzwerte sicher einzuhalten. Darüber hinaus bieten sich Staubabscheider an, freiwillig einen größeren Beitrag zur Feinstaubemissionsreduktion zu leisten

DNA damage-induced translocation of S100A11 into the nucleus regulates cell proliferation

<p>Abstract</p> <p>Background</p> <p>Proteins are able to react in response to distinct stress stimuli by alteration of their subcellular distribution. The stress-responsive protein S100A11 belongs to the family of multifunctional S100 proteins which have been implicated in several key biological processes. Previously, we have shown that S100A11 is directly involved in DNA repair processes at damaged chromatin in the nucleus. To gain further insight into the underlying mechanism subcellular trafficking of S100A11 in response to DNA damage was analyzed.</p> <p>Results</p> <p>We show that DNA damage induces a nucleolin-mediated translocation of S100A11 from the cytoplasm into the nucleus. This translocation is impeded by inhibition of the phosphorylation activity of PKCα. Translocation of S100A11 into the nucleus correlates with an increased cellular p21 protein level. Depletion of nucleolin by siRNA severely impairs translocation of S100A11 into the nucleus resulting in a decreased p21 protein level. Additionally, cells lacking nucleolin showed a reduced colony forming capacity.</p> <p>Conclusions</p> <p>These observations suggest that regulation of the subcellular distribution of S100A11 plays an important role in the DNA damage response and p21-mediated cell cycle control.</p

Physisorption of molecular oxygen on single-wall carbon nanotube bundles and graphite

We present a study on the kinetics of oxygen adsorption and desorption from single-wall carbon nanotube ͑SWNT͒ and highly oriented pyrolytic graphite ͑HOPG͒ samples. Thermal-desorption spectra for SWNT samples show a broad desorption feature peaked at 62 K, which is shifted to a significantly higher temperature than the low-coverage desorption feature on HOPG. The low-coverage O 2 binding energy on SWNT bundles ͑18.5 kJ/mol͒ is 55% higher than that for adsorption on HOPG ͑12.0 kJ/mol͒. In combination with molecular mechanics calculations we show that the observed binding energies for both systems can be attributed to van der Waals interactions, i.e., physisorption. The experiments provide no evidence for a more strongly bound chemisorbed species or for dissociative oxygen adsorption

Is spin-charge separation observable in a transport experiment?

We consider a one-dimensional chain consisting of an interacting area coupled to non-interacting leads. Within the area, interaction is mediated by a local on-site repulsion. Using real time evolution within the Density Matrix Renormalisation Group (DMRG) scheme, we study the dynamics of wave packets in this two-terminal transport setup. In contrast to previous works, where excitations were created by adding potentials to the Hamiltonian, we explicitly create left moving single particle excitations in the right lead as the starting condition. Our simulations show that such a transport setup allows for a clear detection of spin-charge separation using time-resolved spin-polarised density measurements.Comment: 5 pages, 4 figures. accepted by Europhysics Letter