bluuebunny/crossref_metadata_2025 huggingface dataset:
Mindestbewehrung zur Begrenzung der Rissbreiten in Stahlbetonbauteilen infolge des Hydratationsprozesses
Authors: Bödefeld Jörg , Ehmann Rainer , Schlicke Dirk , Tue Nguyen Viet
Published: January 2012

Zwang während des Hydratationsprozesses kann zu Rissbildung führen. Zur Sicherstellung der Gebrauchstauglichkeit müssen die Rissbreiten entsprechend den Expositionsklassen begrenzt werden. Das derzeit in Massivbaunormen auf den Rissschnittgrößen basierende Konzept zur Ermittlung der Mindestbewehrung weist einige Schwächen auf, insbesondere für dicke Bauteile. Mit dem auf der Verformungskompatibilität basierenden, neu entwickelten Konzept können diese Schwächen aufgehoben werden. Maßgebend im neuen Konzept ist die aufzunehmende Verformungseinwirkung und nicht der Zeitpunkt der Rissbildung. Weiterhin können die wesentlichen Parameter der Betontechnologie wie Wärmeentwicklung und Nachbehandlung quantitativ erfasst werden. Die Überlagerung zwischen frühem und spätem Zwang kann ebenfalls auf einer gemeinsamen, mechanischen Grundlage beantwortet werden. Die neu gewonnenen Erkenntnisse fließen bereits in das neue Merkblatt “Früher Zwang” der Bundesanstalt für Wasserbau ein.

Minimum Reinforcement for Crack Control in Hardening Concrete Members. Part 1: Cracking Force based Approach according to DIN EN 1992‐1‐1

Hydration induced restraint forces can lead to crack formation in hardening concrete members. Securing serviceability and durability of the construction crack widths have to be limited according to exposition class. For this actual standards use the concept of the cracking force. This approach is not free from failings, especially for thick concrete members. The new approach introduced in this article is based on the deformation compatibility and abolishes those failures. The authoritative of this concept is the absorption of the impacting deformation, not the time of crack formation as in the former approach. Thus essential parameters of concrete technology as heat development and curing can be considered quantitative. Furthermore the superposition of early restraint and restraint forces in the use period can be analysed on a common mechanic base. These new findings are the base of the new technical report “Early Restraint” of the Federal Waterways Engineering and Research Institute.
Hochleistungsleichtbeton unter Impakt
Authors: Quast Matthias , Hummeltenberg Anja , Curbach Manfred
Published: January 2012

Die Sicherheit von Bauwerken gegen hochdynamische Beanspruchungen gewinnt seit einigen Jahren zunehmend an Bedeutung. Ob durch Fahrzeuganprall oder Steinschlag hervorgerufen ist ein Impaktereignis immer eine außergewöhnliche Belastung für ein Bauwerk. Durch die bei diesen hochdynamischen Vorgängen wirkenden Belastungsgeschwindigkeiten verändert sich das Materialverhalten von Beton signifikant gegenüber dem statischen Fall. Für eine realitätsnahe Bauwerksbemessung gegenüber Impakt muss das verzerrungsratenabhängige Materialverhalten verschiedener Betone noch besser erforscht werden. Durch die hier vorgestellten Versuche an Leichtbetonen soll ein Beitrag auf diesem Gebiet geleistet werden.

Nach der Beschreibung der verwendeten Hochleistungsleichtbetone und einer Erläuterung des Versuchsaufbaus des Split‐Hopkinson‐Bars (SHB) sowie der Messtechnik werden die durchgeführten Experimente für Dehnraten von 50 bis 150 1/s vorgestellt und die gewonnen Ergebnisse erläutert. Die Untersuchungen zeigen, dass Leichtbeton im Bereich hoher Belastungsgeschwindigkeiten ein ähnliches Verhalten wie hochfeste Normalbetone aufweist.

High Performance Lightweight Aggregate Concrete under Impact Loading

The resistance of civil engineering constructive works to high dynamic loadings has become increasingly important in recent years. Whether caused by a vehicle collision or falling rocks, an impact event is always an extraordinary load on a building. Due to the high dynamic processes acting at these loading rates, the material properties of concrete are changing significantly compared to the static case. To improve the building design to impact, it is important to know more about the strain rate dependent material behaviour of different types of concrete. The presented experiments on lightweight concrete should make a contribution in this field.

After the description of the high performance lightweight aggregate concrete, an explanation of the experimental setup of the Split‐Hopkinson‐Bar (SHB) and the measurement technique, the experiments carried out for strain rates of 50 to 150 1/s are presented and the results obtained are discussed. The investigations show that lightweight concrete has a similar behaviour as normal high performance concrete at high loading rates.
International Headquarter Salewa
Authors: Kauer Ulrich
Published: January 2012

Der Sportartikelhersteller Salewa errichtete südlich von Bozen, von der Brennerautobahn gut ersichtlich, seine neue Firmenzentrale. Mit über 350.000 m3 Gesamtbauvolumen gehört das Projekt zu den größten Bauvorhaben Südtirols und wird eine ganze Reihe von Geschäftsfeldern und Aktivitäten rund um die Themen Mensch, Berg, Design und Innovation beheimaten. Das internationale Marketing und die Verwaltung finden hier ebenso Platz wie ein eigenes Forschungszentrum zur Produktentwicklung, ein vollautomatisiertes Lagersystem, eine öffentliche Parkanlage, ein eigener Kindergarten sowie die größte Kletterhalle Italiens mit 2.000 m2 Kletterfläche und über 90 Kletterrouten.
PC Bonds as Building Blocks for Three‐ and Four‐Membered Heterocyclic Cations: Synthesis, Structures and Mechanistic Studies
Authors: Bates Joshua I. , Gates Derek P.
Published: January 2012

The activation of the PC bond of phosphaalkenes with electrophiles is investigated as a means to prepare and characterize unusual organophosphorus compounds. Treatment of RPCHtBu (1 a: R=tBu; 1 b: R=1‐adamantyl) with HOTf (0.5 equiv) affords diphosphiranium salts [RPCHtBuPR (CH2tBu)]OTf ([2 a]OTf and [2 b]OTf), each containing a three‐membered P2C ring. In contrast, the addition of MeOTf (0.5 equiv) to either 1 a or 1 b affords diphosphetanium salts [RPCHtBuP(Me)RCHtBu]OTf ([3 a]OTf and [3 b]OTf) containing four‐membered P2C2 heterocycles. The phosphenium triflate [tBuP(CH2tBu)]OTf ([5 a]OTf) and methylenephosphonium triflate [tBu(Me)PCHtBu]OTf ([7 a]OTf) are identified spectroscopically as intermediates in the formation of [2 a]+ and [3 a]+, respectively. The phosphenium triflate intermediate can be trapped with 2‐butyne to afford phosphirenium salt [MeCCMetBuPCH2tBu]OTf ([6 a]OTf). Treatment of diphosphetanium [3 a]OTf with an excess MeOTf affords [Me2PCHtBuPMetBuCHtBu](OTf)2 ([4 a](OTf)2), a compound containing a diphosphetanium dication. The molecular structures are reported for [2 a]OTf, [2 b][H(OTf)2], [3 a]I, [3 b]I, [4 a](OTf)2, and [6 a]OTf.
β‐Cyclodextrin/Glycyrrhizic Acid Functionalised Quantum Dots Selectively Enter Hepatic Cells and Induce Apoptosis
Authors: Zhao Mei‐Xia , Ji Liang‐Nian , Mao Zong‐Wan
Published: January 2012

The use of active components from important medical herbs has proved effective in treating various cancers. Glycyrrhizic acid (GA) is one of the many interesting triterpenoic acids with anticancerogenic potential, and is known to trigger apoptosis in hepatocarcinoma cells. In this study we combined quantum dots (QDs) with GA in the presence of β‐cyclodextrin (β‐CD), and prepared β‐CD/GA‐functionalised QDs, which led to improved antitumor activity and induced apoptosis in hepatocarcinoma cells. These compounds showed a better selectivity for hepatic cells compared to HeLa and ECV‐304 cells. Hoechst and annexin V–FITC staining and mitochondrial membrane potential (MMP) experiments proved an apoptotic effect of these compounds on HepG2 cells. At the same time, transmission electron microscopy (TEM) showed obvious features of apoptosis, for example, irregularities of nuclear shapes, mitochondria swelling, clumping and peripheral chromatin condensation, zeiosis or blebbing of the plasma membrane and formation of apoptotic bodies. It is notable that β‐CD/GA‐functionalised QDs showed effective cell growth inhibition by triggering G0/G1 phase arrest and inducing apoptosis through an reactive oxygen species mediated mitochondrial dysfunction pathway. β‐CD/GA‐functionalised QDs primarily induced apoptotic response in a time‐ and dose‐dependent manner, but little apoptosis appeared with L‐Cys‐β‐CD‐functionalised QDs or GA alone. These studies suggest that β‐CD/GA‐functionalised QDs have therapeutic potential against cancer.
Diffusive Shielding Stabilizes Bulk Nanobubble Clusters
Authors: Weijs Joost H. , Seddon James R. T. , Lohse Detlef
Published: January 2012

Using molecular dynamics, we study the nucleation and stability of bulk nanobubble clusters. We study the formation, growth, and final size of bulk nanobubbles. We find that, as long as the bubble‐bubble interspacing is small enough, bulk nanobubbles are stable against dissolution. Simple diffusion calculations provide an excellent match with the simulation results, giving insight into the reason for the stability: nanobubbles in a cluster of bulk nanobubbles protect each other from diffusion by a shielding effect.
Molecular‐Scale Interface Engineering of Nanocrystalline Titania by Co‐adsorbents for Solar Energy Conversion
Authors: Wang Mingkui , Plogmaker Stefan , Humphry‐Baker Robin , Pechy Peter , Rensmo Håkan , Zakeeruddin Shaik. M. , Grätzel Michael
Published: January 2012

The use of mixed self‐assembled monolayers, combining hydrophobic co‐adsorbents with the sensitizer, has been demonstrated to enhance the efficiency of dye‐sensitized solar cells (DSCs). Herein, the influence of the anchoring groups of the co‐adsorbents on the performance of the DSCs is carefully examined by selecting two model molecules: neohexyl phosphonic acid (NHOOP) and bis‐(3,3‐dimethyl‐butyl)‐phosphinic acid (DINHOP). The effect of these co‐adsorbents on the photovoltaic performance (J–V curves, incident photon‐to‐electron conversion efficiency) is investigated. Photoelectron spectroscopy and electrochemical impedance spectroscopy are performed to assess the spatial configuration of adsorbed dye and co‐adsorbent molecules. The photoelectron spectroscopy studies indicate that the ligands of the ruthenium complex, containing thiophene groups, point out away from the surface of TiO2 in comparison with the NCS group.
18F‐Radiolabeling of Aromatic Compounds Using Triarylsulfonium Salts
Authors: Mu Linjing , Fischer Cindy R. , Holland Jason P. , Becaud Jessica , Schubiger P. August , Schibli Roger , Ametamey Simon M. , Graham Keith , Stellfeld Timo , Dinkelborg Ludger M. , Lehmann Lutz
Published: January 2012

A new method for the 18F‐radiolabeling of aromatic compounds based on the aromatic nucleophilic substitution (SNAr) reaction using triarylsulfonium salts has been developed. Experiments and DFT calculations indicated that sulfonium ions have the potential to be optimized for labeling nonactivated and deactivated aryl rings that have Hammett σP substituent constants greater than –0.170. This method is applicable to a range of halogen‐substituted aryl systems including nonactivated and deactivated aryl rings. In particular, the high radiochemical yield of [18F]‐4‐fluoroiodobenzene from precursor 1a represents a ready source of compound 1b for subsequent use in palladium‐catalyzed C–H activation/C–C bond‐forming reactions.
Functional role for interleukin‐1 in the injured peripheral taste system
Authors: Shi Liqiao , He Lianying , Sarvepalli Padma , McCluskey Lynnette Phillips
Published: January 2012

The peripheral taste system presents an excellent model for studying the consequences of neural injury, for the damaged nerve and sensory cells and the neighboring, intact neural cells. Sectioning a primary afferent nerve, the chorda tympani (CT), rapidly recruits neutrophils to both sides of the tongue. The bilateral neutrophil response induces transient functional deficits in the intact CT. Normal function is subsequently restored as macrophages respond to injury. We hypothesized that macrophages produce the proinflammatory cytokine interleukin (IL)‐1, which contributes to the maintenance of normal taste function after nearby injury. We demonstrate that IL‐1β protein levels are significantly increased on the injured side of the tongue at day 2 after injury. Dietary sodium deficiency, a manipulation that prevents macrophage recruitment, inhibits the elevation in IL‐1β. IL‐1β was expressed in several cell populations, including taste receptor cells and infiltrating neutrophils and macrophages. To test whether IL‐1 modulates taste function after injury, we blocked signaling with an IL‐1 receptor antagonist (IL‐1 RA) and recorded taste responses from the intact CT. This treatment inhibited the bilateral macrophage response to injury and impaired taste responses in the intact CT. Cytokine actions in the taste system are largely unstudied. These results demonstrate that IL‐1 has a beneficial effect on taste function after nearby injury, in contrast to its detrimental role in the injured central nervous system. © 2012 Wiley Periodicals, Inc.
Correlatives
Authors: Brasoveanu Adrian
Published: January 2012

The paper reviews the semantics and pragmatics of correlatives across various ontological domains (temporal, modal, individual and degree domains), focusing mostly on Indo‐European languages. Taking correlatives in the individual domain as a case study, the paper then argues that their interpretation, in particular the variability of the uniqueness effects exhibited by correlatives, is due to their mixed referential and quantificational nature. The account involves an articulated notion of quantification consisting of both (discourse) referential components and non‐referential/quantificational components – thus bringing together previous analyses that took either the referential or the quantificational route. The variable uniqueness effects emerge out of the interaction between (i) the semantics of wh‐indefinites, singular anaphors and habitual morphology and (ii) the pragmatics of quantification, which allows for the selection of different levels of ‘zoom‐in’ on the quantified‐over objects.
The Computation of Scalar Implicatures: Pragmatic, Lexical or Grammatical?
Authors: Sauerland Uli
Published: January 2012

I provide an overview of four current theories of scalar implicature: the pragmatic (orGricean), the lexical, a combined pragmatic + lexical, and the grammatical theory. The empirical focus are global and local, but also intermediate implicatures. I argue that the grammatical theory is conceptually less well motivated than even the pragmatic + lexical theory, and that the grammatical theory therefore requires strong empirical support. I then focus on a novel empirical phenomenon – intermediate implicatures – which provides empirical support for the grammatical theory. I conclude that it seems necessary to adopt the grammatical theory.
The Cross‐Linguistic Prevalence of SOV and SVO Word Orders Reflects the Sequential and Hierarchical Representation of Action in Broca’s Area
Authors: Kemmerer David
Published: January 2012

Despite the increasingly interdisciplinary nature of the language sciences, so far relatively little effort has been devoted to exploring potential connections between typology and neuroscience. To illustrate some of the insights that can be gained from pursuing such an integration, this paper focuses on one of the most well established and frequently cited typological generalizations, namely that in the vast majority of human languages, the basic word order is either SOV (about 48%) or SVO (about 41%). It has been suggested that these strong tendencies can be explained cognitively in terms of the prototypical transitive action scenario, in which an animate agent acts forcefully on an inanimate patient to induce a change of state. Two forms of iconicity are especially relevant: first, because the agent is at the head of the causal chain that affects the patient, subjects usually precede objects; and second, because it is the agent’s action, rather than the agent per se, that changes the state of the patient, verbs and objects are usually adjacent. The purpose of this paper is to show that this account converges with, and hence receives further support from, recent research on how actions are represented in the brain. Specifically, several lines of evidence are reviewed which suggest that Broca’s area plays a pivotal role in schematically representing the sequential and hierarchical organization of goal‐directed bodily movements, not only when they are performed and perceived in the real world, but also when they are conceptualized and symbolically expressed as transitive clauses. Taken together, these findings support the hypothesis that the most cross‐linguistically prevalent word order patterns reflect the most natural ways of linearizing and nesting the core conceptual components of actions in Broca’s area.
Finite speed of propagation in 1‐D degenerate Keller‐Segel system
Authors: Sugiyama Yoshie
Published: January 2012

We consider the following Keller‐Segel system of degenerate type: (KS):\documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\frac{\partial u}{\partial t} = \frac{\partial }{\partial x} \big ( \frac{\partial u^m}{\partial x} - u^{q-1} \frac{\partial v}{\partial x} \big ), x \in {\mathbb R}, t>0, 0 = \frac{\partial ^2 v}{\partial x^2} - \gamma v + u, x \in {\mathbb R}, t>0, u(x,0) = u_0(x), x \in {\mathbb R},$\end{document}wherem> 1, γ > 0, q⩾ 2m. We shall first construct a weak solutionu(x,t) of (KS) such thatum− 1is Lipschitz continuous and such that\documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\displaystyle u^{m-1+\delta }$\end{document}for δ > 0 is of classC1with respect to the space variablex. As a by‐product, we prove the property of finite speed of propagation of a weak solutionu(x,t) of (KS), i.e., that a weak solutionu(x,t) of (KS) has a compact support inxfor allt> 0 if the initial datau0(x) has a compact support in\documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}${\mathbb R}$\end{document}. We also give both upper and lower bounds of the interface of the weak solutionuof (KS).
Besov space and trace theorem on a local field and its application
Authors: Kaneko Hiroshi
Published: January 2012

Recently, importance of the Besov space has been acknowledged by analysts studing such subsets with lower dimension than the whole space as fractals in the Euclidean space. On the other hand, by taking an extension K of local field K′, K′ is contained in K as a subset with lower dimension than the whole space K and the present author showed that it can be viewed as a d‐set of K in terms of fractal analysis. In this article, Besov spaces on separable extension of the field of p‐adic numbers and on its d‐set will be consistently introduced. After that, a trace theorem showing a relationship between those Besov spaces will be presented and finally a penetrating stochastic process into K′ will be addressed as an application of the trace theorem.
Repulsive knot energies and pseudodifferential calculus for O’Hara’s knot energy family E(α), α ∈ [2, 3)
Authors: Reiter Philipp
Published: January 2012

We develop a precise analysis of J. O’Hara’s knot functionals E(α), α ∈ [2, 3), that serve as self‐repulsive potentials on (knotted) closed curves. First we derive continuity of E(α) on injective and regular H2 curves and then we establish Fréchet differentiability of E(α) and state several first variation formulae. Motivated by ideas of Z.‐X. He in his work on the specific functional E(2), the so‐called Möbius Energy, we prove C∞‐smoothness of critical points of the appropriately rescaled functionals \documentclass{article}\usepackage{amssymb}\begin{document}\pagestyle{empty}$\tilde{E}^{(\alpha )}= {\rm length}^{\alpha -2}E^{(\alpha )}$\end{document} by means of fractional Sobolev spaces on a periodic interval and bilinear Fourier multipliers.
Existence of homoclinic solutions for a class of asymptotically quadratic non‐autonomous Hamiltonian systems
Authors: Zhang Qiongfen , Tang X. H.
Published: January 2012

By using the variant version of Mountain Pass Theorem, the existence of homoclinic solutions for a class of asymptotically quadratic non‐autonomous Hamiltonian systems is obtained. The result obtained generalizes and improves some known works.
Anisotropic function spaces and elliptic boundary value problems
Authors: Nguyen Timothy
Published: January 2012

In this paper, we study anisotropic Bessel potential and Besov spaces, where the anisotropy measures the extra amount of regularity in certain directions. Some basic properties of these spaces are established along with applications to elliptic boundary value problems.
Martingale Orlicz‐Hardy spaces
Authors: Miyamoto Takashi , Nakai Eiichi , Sadasue Gaku
Published: January 2012

The purpose of this paper is to introduce five martingale Orlicz‐Hardy spaces and to establish the atomic decomposition theorem. As applications we show the relation among five martingale Orlicz‐Hardy spaces and the duality, namely, the dual of martingale Orlicz‐Hardy spaces are generalized martingale Campanato spaces. Further, we prove a John‐Nirenberg type inequality for generalized martingale Campanato spaces when the stochastic basis is regular.
Classification Models for Predicting Cytochrome P450 Enzyme‐Substrate Selectivity
Authors: Zhang Tao , Dai Hao , Liu Limin Angela , Lewis David F. V. , Wei Dongqing
Published: January 2012

Cytochrome P450 (CYP) is an important drug‐metabolizing enzyme family. Different CYPs often have different substrate preferences. In addition, one drug molecule may be preferentially metabolized by one or more CYP enzymes. Therefore, the classification and prediction of substrate specificity of CYP enzymes are of importance to the understanding of drug metabolisms and may help guide the development of new drugs. In this study, we used three different machine learning methods to classify CYP substrates for predicting CYP‐substrate specificity based solely on structural and physicochemical properties of the substrates. We first built a simple decision tree model to classify substrates of four CYP enzymes, 1A2, 2C9, 2D6 and 3A4 with more than 78 % classification accuracy. We then built a single‐label eight‐class model and a multilabel five‐class model to classify substrates of eight CYP enzymes and to classify substrates that can be metabolized by more than one CYP enzymes, respectively. Above 90 % and >80 % prediction accuracy was achieved for the single‐label and multilabel models, respectively. The main improvement of our models over existing ones is the automated and unbiased selection of descriptors by genetic algorithms, which makes our methods applicable for larger data sets and increased number of CYP enzymes.
Zur Geschichte der Tuberkulosebehandlung
Authors: Grundmann Kornelia , Friedrich Christoph
Published: January 2012

Die Tuberkulose zählt zu den Infektionskrankheiten, deren Geschichte bis in die Antike zurückreicht. Bis zur Mitte des 20. Jahrhunderts war sie global verbreitet und wies hohe Todesraten auf. In der zweiten Hälfte des 20. Jahrhunderts verlor sie indes in den hoch entwickelten Ländern der westlichen Welt ihre Schrecken und schien sogar in vielen Ländern völlig verschwunden zu sein, was vor allem einer wirksamen Arzneimitteltherapie zu danken war.
Biologie der Mykobakterien und neue molekulare Targets
Authors: Koch Oliver , Selzer Paul M.
Published: January 2012

Mykobakterien sind von Natur aus mit einer hohen Widerstandsfähigkeit gegenüber äußeren Umwelteinflüssen und Antibiotika ausgestattet. Die daher notwendige langdauernde Antibiotika‐Gabe und das Auftreten multiresistenter Stämme begründen den Bedarf an neuen Therapiemöglichkeiten mit neuen Wirkmechanismen.
Klinische Aspekte der Tuberkulose
Authors: Müller Andreas
Published: January 2012

Die Tuberkulose ist eine Erkrankung von immenser globaler Bedeutung, die mit in ihrem vielfältigen Erscheinungsbild und ihrer komplexen Diagnostik und Therapie noch immer eine klinische Herausforderung darstellt. Die zunehmende Resistenzproblematik macht die Entwicklung neuer effizienter Therapiestrategien zu einer Aufgabe höchster Priorität.
Die Suche nach neuen Antituberkulotika
Authors: Laqua Katja , Rudolph Ines , Imming Peter
Published: January 2012

Viele Hürden erschweren die Forschung nach neuen Antituberkulotika. Nicht nur neue Substanzen werden dringend benötigt, auch die Kriterien zur Bewertung, neue Tiermodelle und Biomarker sind unumgänglich. Die schon vielversprechende Pipeline ist ein Ergebnis vieler Initiativen in der TB‐Forschung, vor allem die Arbeit der Private‐Public‐Partnerships leistet einen großen Beitrag, neue Substanzen in die Pipeline zu “befördern”. Zum Glück scheint auch die Industrie “erwacht”, an Tuberkulose zu forschen, wie ein sprunghafter Anstieg der Firmenpatente mit dem Thema Tuberkulose in den letzten acht Jahren zeigt. Der aussichtsreichste Wirkstoff in der Pipeline ist derzeit TMC207 (Bedaquilin).
Tuberkulose/HIV/AIDS – Prävention und Therapie in Ghana
Authors: Kenu Ernest , Käser Michael
Published: January 2012

Unter den 9,4 Millionen neuen Tuberkulose‐Fällen weltweit im Jahr 2009 waren 1,1 Millionen Menschen HIV‐positiv. Durch den Anstieg an HIV‐Infektionen wurde die HIV/AIDS‐assoziierte Tuberkulose zum Hauptproblem der nationalen Tuberkulose‐Programme, besonders in Sub‐Sahara‐Afrika. Dort sterben bis zu 30 % der HIV‐positiven Tuberkulose‐Patienten noch vor Beendigung der Tuberkulose‐Therapie. Frühe Diagnose, individuelle Beratung, schnelle Therapie und flächendeckende Prävention sind Schlüsselelemente des Nationalen Tuberkulose‐Programms in Ghana. Durch die vor wenigen Jahren noch undenkbare Verfügbarkeit von Labortests und Medikamenten sind die Erfolgsaussichten zur Reduktion der Tuberkulose‐ und HIV‐Prävalenz groß. Die besonderen Herausforderungen in infrastrukturell schwachen Regionen liegen in der Aufstockung und Schulung von medizinischen Fachkräften und einer nahtlosen Kooperation der Aktivitäten von Tuberkulose‐ und HIV/AIDS‐Zentren.
Die Fettsäuresynthese als Angriffspunkt
Authors: Topf Christine M. , Schiebel Johannes , Kisker Caroline , Holzgrabe Ulrike
Published: January 2012

Seit Jahren begegnet uns allen Triclosan in vielen Alltagsgegenständen, in denen es über eine Hemmung der Fettsäuresynthese antibakteriell wirksam ist; darüber hinaus sind weitere schwach inhibierende Naturstoffe aus Bakterien und Pilzen bekannt. Die Optimierung dieser Substanzen stellt einen vielversprechenden Ansatz zur Entwicklung neuer Antituberkulotika dar, wobei sowohl die Selektivität für die mykobakterielle Fettsäuresynthese als auch die Aufnahme der Substanzen in das Mykobakterium eine große Hürde darstellen.
Resistenzen importiert aus Russland
Authors: Mütterlein Ralf
Published: January 2012

Aus den Staaten der ehemaligen Sowjetunion kommen viele Patienten nach Europa, die an MDR/XDR‐Tuberkulose leiden. Auf Grund dieser schwierigen Resistenzlage können sie nur in Spezialkliniken fachgerecht und erfolgreich behandelt werden.
Tuberkulose unter TNFα‐Inhibitoren
Authors: Trautmann Matthias
Published: January 2012

TNFα‐Inhibitoren finden zur Therapie verschiedener Erkrankungen des rheumatischen Formenkreises zunehmende Verwendung. Da TNFα für die Aufrechterhaltung einer immunologischen Balance bei chronisch‐persistierenden Infektionen von essentieller Bedeutung ist, kann es jedoch durch TNFα‐Blockade zu einem Aufflackern latenter, persistierender Infektionen kommen. Von größter Bedeutung ist in diesem Zusammenhang die Reaktivierung einer latenten Tuberkulose. Unter TNFα‐Inhibitortherapie ist das Risiko einer TB‐Reaktivierung um den Faktor 9 bis 16 erhöht. Extrapulmonale und disseminierte TB‐Verläufe sind unter TNFα‐Inhibitortherapie deutlich häufiger als bei spontanem Auftreten einer TB. Vor Beginn einer TNFα‐Inhibitortherapie muss daher durch klinische, radiologische und immunologische Diagnostik eine latente TB möglichst sicher ausgeschlossen werden. Besteht die Notwendigkeit des Einsatzes eines TNFα‐Inhibitors trotz Hinweisen für eine latente TB, muss zunächst eine präventive Chemotherapie mit Isoniazid vorgeschaltet werden.
FRET zur Bestimmung der minimalen Hemmkonzentration von Antibiotika
Authors: Holzgrabe Ulrike
Published: January 2012

Die Bestimmung der Minimalen Hemmkonzentration (MHK) von Antibiotika ist nicht nur wichtig, wenn es darum geht, nach neuen antimikrobiellen Substanzen zu suchen, sondern auch für die Bestimmung der Empfindlichkeit von Erregern gegen die zum Einsatz geplanten Antibiotika, d.h. zur Erhebung des Resistenzstatus.
Phenolic Compounds and Anti‐oxidant Capacity of Twelve Morphologically Heterogeneous Bamboo species
Authors: Hoyweghen Laura Van , Beer Thomas De , Deforce Dieter , Heyerick Arne
Published: January 2012

Introduction

Despite the growing interest in the use of bamboo for both food and health‐related applications because it provides a rich source of anti‐oxidants, there is still a lack of information on the responsible secondary metabolites of the great variety of bamboo species.

Objective

To extend the knowledge on secondary metabolites of different bamboo species and to link anti‐oxidant capacity with the different classes of phenolic compounds that are present in the leaves.

Methodology

Chromatographic profiles of 12 morphological heterogeneous bamboo species from different genera were recorded using HPLC‐DAD (diode array detector) and LC‐MS/MS. In addition, the in vitro anti‐oxidant capacity was evaluated using a variety of anti‐oxidant assays (1,1‐diphenyl‐2‐picrylhydrazyl, Trolox‐equivalent anti‐oxidant capacity and oxygen radical absorbance capacity). Using partial least square (PLS) analysis as a chemometric method, the anti‐oxidant capacity could be linked to specific groups of polyphenols.

Results

Flavones and phenolic acids are the two main polyphenolic classes present in the leaf extracts of the 12 selected bamboo species. Luteolin derivatives and phenolic acids were identified as the most potent anti‐oxidants.

Conclusion

The most abundant classes of phenolic compounds present in a selection of bamboo species were flavone glycosides and phenolic acids. Luteolin flavones and phenolic acids are the main anti‐oxidant phenolic compounds in bamboo leaf extract. The information obtained in this study provides further support for the development of bamboo‐based anti‐oxidant food applications and food supplements. Copyright © 2012 John Wiley & Sons, Ltd.
Baukasten für Superschwergewichte
Authors: Hofmann Sigurd
Published: January 2012

Durch den Bau leistungsfähiger Beschleuniger für schwere Ionen und empfindlicher Nachweisverfahren wurde die Zahl der bekannten Elemente auf heute 118 erhöht. Die Eigenschaften der Reaktionen selbst und der erzeugten Isotope zeigen, dass die schwersten Kerne auf einer Insel der Stabilität liegen, die vom Schalenmodell für Atomkerne vorhergesagt wurde. Ziel weiterer Forschungen ist die detaillierte Erkundung dieser Insel im Hinblick auf ihre Ausdehnung als Funktion der Zahl der Protonen und Neutronen und unter dem Aspekt der längsten Lebensdauern der Isotope.
Menschliche Adler
Authors: Mathelitsch Leopold , Thaller Sigrid
Published: January 2012

Aus physikalischer Sicht unterscheiden sich die beiden Sportarten Skispringen und Skifliegen nur graduell. Drei physikalische Parameter beeinflussen die Weite besonders stark: die Abfluggeschwindigkeit normal zur Schanze, das richtige Drehmoment des Körpers beim Absprung und der Winkel zwischen Körperachse und Skiern nach 20 m Flug. Die Rotation beim Sprung nach vorne verhindert zudem, dass der plötzliche Auftrieb der Skier den Springer auf den Rücken dreht. Zusätzlichen Auftrieb bringt die V‐Stellung der Skier. Da leichtere Sportler weiter springen, sollen seit 2004 Regeln gefährliche Magersucht verhindern. Seit 2009 wird der beim Sprung herrschende Wind in der Bewertung berücksichtigt.
Das Weltraumexperiment PAMELA
Authors: Simon Manfred
Published: January 2012

Das Experiment PAMELA hat die Messungen der Antiprotonen, Positronen und Elektronen in der kosmischen Strahlung deutlich verbessert. Ein gemessener Überschuss von Positronen bei hohen Energien hat eine heiße Diskussion über deren Ursprung ausgelöst. Denkbar ist zwar ein Zerfall von Dunkle‐Materie‐Teilchen, derzeit werden jedoch astrophysikalische Quellen wie Pulsare favorisiert. Mit weiteren und neuen Experimenten ließe sich die Empfindlichkeit bei der Suche nach Antiheliumkernen verbessern. Das streben Forscher mit dem Alpha‐Magnet‐Spektrometer (AMS) an, das seit Mai 2011 auf der Internationalen Weltraumstation arbeitet. Es wäre auch wünschenswert, die Messung der Positronen, Antiprotonen und Elektronen zu erweitern. So könnte es schließlich doch noch auf diesem Weg gelingen, die Dunkle‐Materie‐Hypothese zu bestätigen oder zu verwerfen.
Pioneer‐Rätsel gelöst
Authors: Lämmerzahl Claus , Rievers Benny
Published: January 2012

In den Jahren 1972 und 1973 starteten die baugleichen Raumsonden Pioneer 10 und 11 ins All und erforschten erstmals das äußere Sonnensystem. Seit Ende der 1980er Jahre ist bekannt, dass beide Sonden eine negative Beschleunigung von etwa 8 · 10–10 m/s2 erfahren. Die Ursache blieb lange unklar und wurde als Pioneer‐Anomalie bekannt. Ein detailliertes Thermalmodell der Sonde hat nun gezeigt, dass die Abbremsung höchstwahrscheinlich von einer anisotropen Wärmeabstrahlung herrührt.
Dem Higgs‐Boson auf der Spur
Authors: Müller Thomas
Published: January 2012

Am 13. Dezember letzten Jahres präsentierten die Sprecher der beiden Großexperimente ATLAS und CMS am Large Hadron Collider (LHC) die mit großer Spannung erwarteten, neuesten Resultate von der Suche nach dem Higgs‐Boson. Es ist das Quant für ein skalares Feld, welches bewirkt, dass die W‐ und Z‐Bosonen der elektroschwachen Wechselwirkung eine (sehr hohe) Masse besitzen, während das Photon bekanntlich masselos ist. Zusätzlich erhalten Fermionen durch Ankopplung an das Higgs‐Feld eine Ruhemasse. Der Nachweis des Higgs‐Teilchens und die Vermessung seiner Eigenschaften sind von außerordentlich großer Bedeutung, würde es doch das Standardmodell der Elementarteilchenphysik vervollständigen.
Farbenfrohe Eisschollen
Authors: Schlichting H. Joachim
Published: January 2012

In bunten Farben schillernde Eisschollen verdeutlichen, dass Eis doppelbrechend ist. Darüber hinaus zeugt es von der teilweisen Polarisation des Himmelslichts.
Feynmans Rätsel der brechenden Spaghetti
Authors: Vollmer Michael , Möllmann Klaus‐Peter
Published: January 2012

Wenn man eine ungekochte Spaghetti‐Nudel an beiden Enden fasst und zerbricht, entstehen immer drei Bruchstücke oder mehr, nie jedoch nur zwei. Warum das so ist, fragte sich schon Richard Feynman. Mittlerweile ist die Frage geklärt, und Hochgeschwindigkeitsaufnahmen zeigen den Vorgang im Detail.
Schnappschüsse einer chemischen Reaktion
Authors: Kraus Peter M. , Wörner Hans Jakob
Published: January 2012

Chemische Reaktionen werden durch Änderungen der äußersten Elektronen in der Valenzschale gesteuert. Dies geschieht auf der Zeitskala von Attosekunden (10–18 s). Kürzlich ist es unserer Gruppe an der ETH Zürich in Zusammenarbeit mit Kollegen aus Kanada und Frankreich erstmals gelungen, diese Elektronenbewegung während einer chemischen Reaktion zu beobachten. Als Modellsystem diente dabei die Elektronendynamik des Stickstoffdioxidmoleküls (NO2) nach Ultravioletteinstrahlung.
Ligand‐site exchange in intramolecular complexes of silicon: substituent effects
Authors: Kuznetsova Olga V. , Egorochkin Alexey N. , Negrebetsky Vadim V. , Khamaletdinova Nadiya M. , Domratcheva‐Lvova Lada G.
Published: January 2012

The intramolecular complexes containing coordination bonds Si←N or Si←O are distinguished for their stereochemical nonrigidity resulting in interconversion between isomers, that is, ligand‐site exchange. The influence of the substituents bound to the silicon atom on the free energies of activation for ligand exchange ΔG≠ of specific interest is poorly understood. In this work, the literature data on substituent influence on the energies ΔG≠ for 13 series of the complexes have been considered, using the correlation analysis. On the basis of the obedience of the energies ΔG≠ to the linear free energy relationship, it has been established for the first time that the ΔG≠ values depend not only on the inductive and resonance effects but also on the polarizability and steric effects of substituents. The reason for the occurrence of the polarizability effect is the appearance of excess charges on Si and N (or O) atoms as a result of intramolecular coordination consisting in the charge transfer from the donor center (N or O atom) to the acceptor one (Si atom). In some series the contribution of the polarizability or steric effect to the overall change in ΔG≠ because of the influence of substituents is a maximum. An understanding of these effects may give a better insight into the mechanism of nucleophilic substitution, involving organoelement compounds. Copyright © 2012 John Wiley & Sons, Ltd.
Solid‐state Bis‐hexahapto‐metal complexation of single‐walled carbon nanotubes
Authors: Wang Feihu , Itkis Mikhail E. , Bekyarova Elena , Sarkar Santanu , Tian Xiaojuan , Haddon Robert C
Published: January 2012

We report the effect of transition metal deposition on the conductivity of single‐walled carbon nanotube (SWNT) networks. The slow evaporation of small amounts of highly mobile transition metal atoms significantly reduces the resistance of SWNT thin films; we suggest that Cr, Fe, and Ti atoms form bis‐hexahapto complexes at the SWNT sidewalls, thereby bridging adjacent carbon nanotubes and reducing the inter‐nanotube junction resistance. Copyright © 2012 John Wiley & Sons, Ltd.
Migration of nitrogen in hexagonal Ge2Sb2Te5: An ab‐initio study
Authors: Kim Sae‐Jin , Lee Joohwi , Lee Seung‐Cheol , Park Chan , Hwang Cheol Seong , Choi Jung‐Hae
Published: January 2012

The migration barrier energies of the nitrogen atom and N2 molecule, and the activation barriers for the dissociation and formation of N2 in Ge2Sb2Te5 were calculated by ab‐initio methods. Various transition and metastable states were found along the migration pathway. Migration barrier energies up to 1.19 eV for the nitrogen atom suggest that it is difficult for it to move from one site to any other site or diffuse out from Ge2Sb2Te5 although doped nitrogen is energetically less stable with respect to N2 in vacuum. N2 in Ge2Sb2Te5 was hardly expected to dissociate into nitrogen atoms and vice versa. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fermentation of crude glycerol from biodiesel production by Clostridium pasteurianum
Authors: Jensen Torbjørn Ølshøj , Kvist Thomas , Mikkelsen Marie Just , Christensen Peter Vittrup , Westermann Peter
Published: January 2012

Clostridium pasteurianum can utilize glycerol as the sole carbon source for the production of butanol and 1,3-propanediol. Crude glycerol derived from biodiesel production has been shown to be toxic to the organism even in low concentrations. By examination of different pretreatments we found that storage combined with activated stone carbon addition facilitated the utilization of crude glycerol. A pH-controlled reactor with in situ removal of butanol by gas stripping was used to evaluate the performance. The fermentation pattern on pretreated crude glycerol was quite similar to that on technical grade glycerol. C. pasteurianum was able to utilize 111 g/l crude glycerol. The average consumption rate was 2.49 g/l/h and maximum consumption rate was 4.08 g/l/h. At the maximal glycerol consumption rate butanol was produced at 1.3 g/l/h. These rates are higher than those previously reported for fermentations on technical grade glycerol by the same strain. A process including pretreatment and subsequent fermentation of the crude glycerol could be usable for industrial production of butanol by C. pasteurianum.
Human lactoferrin suppresses TNF‐α‐induced intercellular adhesion molecule‐1 expression via competition with NF‐κB in endothelial cells
Authors: Kim Chan Woo , Lee Tae Hoon , Park Keun Hyung , Choi Sang-Yun , Kim Jiyoung
Published: January 2012

Lactoferrin (Lf) is known to have anti‐inflammatory activity, but the mechanisms of action by Lf remain to be elucidated. Here, we demonstrated that TNF‐α‐induced expression of intercellular adhesion molecule‐1 (ICAM‐1) was down‐regulated by Lf in a DNA‐binding dependent manner at transcriptional level in endothelial cells. Our results showed that Lf bound to a DNA region in the ICAM‐1 promoter in vitro as well as in chromatin context. Lf inhibited binding of NF‐κB to a proximal NF‐κB site in ICAM‐1 promoter. This type of repression represents an additional mechanism for the action of Lf in regulation of gene expression.
Scaling up synthetic biology: Do not forget the chassis
Authors: Danchin Antoine
Published: January 2012

Using comparative genomics and functional analysis, this work summarises how the cell's genome is organised, with emphasis on the importance of the cell's chassis. Some discrete but important engineering constraints are reviewed, beginning with the need for scaffolds, as well as the question posed by the difficult task of putting a very long random thread (DNA) into a limited volume. Subsequently, to illustrate overlooked essential functions, we show the importance of safety valves, as well as the need to cope with leftovers. The third section discusses how transplantation experiments point out a remarkable feature of the cell factory: the program replicates (makes identical copies of itself), whereas the cell reproduces (makes similar copies of itself), placing in the limelight the role of informational maintenance. A final section identifies the need to put together a globally linear behaviour of the cell with intrisically non‐linear genetic constructs. The discussion ends with the central question of evolvability of artificial constructs and to suggest that combining in vivo Synthetic Biology with biochemical reactors might be an efficient way forward.
C‐terminal residues of Oryza sativa GUN4 are required for the activation of the ChlH subunit of magnesium chelatase in chlorophyll synthesis
Authors: Zhou Shuaixiang , Sawicki Artur , Willows Robert D. , Luo Meizhong
Published: January 2012

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Tectonics, climate, and mountain topography
Authors: Champagnac Jean‐Daniel , Molnar Peter , Sue Christian , Herman Frédéric
Published: January 2012

By regressing simple, independent variables that describe climate and tectonic processes against measures of topography and relief of 69 mountain ranges worldwide, we quantify the relative importance of these processes in shaping observed landscapes. Climate variables include latitude (as a surrogate for mean annual temperature and insolation, but most importantly for the likelihood of glaciation) and mean annual precipitation. To quantify tectonics we use shortening rates across each range. As a measure of topography, we use mean and maximum elevations and relief calculated over different length scales. We show that the combination of climate (negative correlation) and tectonics (positive correlation) explain substantial fractions (>25%, but <50%) of mean and maximum elevations of mountain ranges, but that shortening rates account for smaller portions, <25%, of the variance in most measures of topography and relief (i.e., with low correlations and large scatter). Relief is insensitive to mean annual precipitation, but does depend on latitude, especially for relief calculated over small (∼1 km) length scales, which we infer to reflect the importance of glacial erosion. Larger‐scale (averaged over length scales of ∼10 km) relief, however, correlates positively with tectonic shortening rate. Moreover, the ratio between small‐scale and large‐scale relief, as well as the relative relief (the relief normalized by the mean elevation of the region) varies most strongly with latitude (strong positive correlation). Therefore, the location of a mountain range on Earth with its corresponding climatic conditions, not just tectonic forcing, appears to be a key factor in determining its shape and size. In any case, the combination of tectonics and climate, as quantified here, can account for approximately half of the variance in these measures of topography. The failure of present‐day shortening rates to account for more than 25% of most measures of relief raises the question: Is active tectonics overrated in attempts to account for present‐day relief and exhumation rates of high terrain?
Precursory deformation and fracture before brittle rock failure and potential application to volcanic unrest
Authors: Kilburn Christopher
Published: January 2012

Small‐magnitude earthquakes and ground deformation are the precursors most frequently recorded before volcanic eruptions. Analogous signals (using acoustic emissions) have also been reported before the bulk brittle failure of crustal rock in the laboratory. Models based on laboratory and field data have focused on precursory behavior during deformation under a constant stress. A new model is proposed for extending analyses to deformation under an increasing stress. It describes how precursory time series can be determined from a parent relation between fracturing and stress, together with time‐dependent changes in applied stress and rock resistance. The model applies to rock in which these stresses do not interact with each other and occupy volumes much smaller than the total volume being deformed. It identifies how the amounts of fracturing observed during deformation are controlled not only by stress concentrations at macroscopic heterogeneities, such as crack tips but also by rock composition, temperature, confining pressure, and the distribution of energy among atoms. The results appear to be scale independent, and so may be used to investigate whether the approach to bulk failure is limited by changes in applied stress or in rock weakening. When applied to pre‐eruptive data from Hawaii, the analysis suggests that precursory signals are controlled by an increase in applied stress, rather than by creep deformation under a constant stress.
High‐precision measurements of ionospheric TEC gradients with the Very Large Array VHF system
Authors: Helmboldt J. F. , Lazio T. J. W. , Intema H. T. , Dymond K. F.
Published: January 2012

We have used a relatively long, contiguous VHF observation of a bright cosmic radio source (Cygnus A) with the Very Large Array (VLA) to demonstrate the capability of this instrument to study the ionosphere. This interferometer, and others like it, can observe ionospheric total electron content (TEC) fluctuations on a much wider range of scales than is possible with many other instruments. We have shown that with a bright source, the VLA can measure differential TEC values between pairs of antennas (δTEC) with a precision of 3 × 10−4 TECU. Here, we detail the data reduction and processing techniques used to achieve this level of precision. In addition, we demonstrate techniques for exploiting these high‐precision δTEC measurements to compute the TEC gradient observed by the array as well as small‐scale fluctuations within the TEC gradient surface. A companion paper details specialized spectral analysis techniques used to characterize the properties of wave‐like fluctuations within this data.