Showing papers by "University of Mons published in 2009"
TL;DR: An overview of the optical and electronic processes that take place in a solid-state organic solar cell, which is defined as a cell in which the semiconducting materials between the electrodes are organic.
Abstract: Our objective in this Account is 3-fold. First, we provide an overview of the optical and electronic processes that take place in a solid-state organic solar cell, which we define as a cell in which the semiconducting materials between the electrodes are organic, be them polymers, oligomers, or small molecules; this discussion is also meant to set the conceptual framework in which many of the contributions to this Special Issue on Photovoltaics can be viewed. We successively turn our attention to (i) optical absorption and exciton formation, (ii) exciton migration to the donor−acceptor interface, (iii) exciton dissociation into charge carriers, resulting in the appearance of holes in the donor and electrons in the acceptor, (iv) charge-carrier mobility, and (v) charge collection at the electrodes. For each of these processes, we also describe the theoretical challenges that need to be overcome to gain a comprehensive understanding at the molecular level. Finally, we highlight recent theoretical advances, ...
1,283 citations
TL;DR: In this article, a review of recent results in the physics of glueballs with the aim set on phenomenology and discuss the possibility of finding them in conventional hadronic experiments and in the Quark Gluon Plasma.
Abstract: Glueballs are particles whose valence degrees of freedom are gluons and therefore in their description the gauge field plays a dominant role. We review recent results in the physics of glueballs with the aim set on phenomenology and discuss the possibility of finding them in conventional hadronic experiments and in the Quark Gluon Plasma. In order to describe their properties we resort to a variety of theoretical treatments which include, lattice QCD, constituent models, AdS/QCD methods, and QCD sum rules. The review is supposed to be an informed guide to the literature. Therefore, we do not discuss in detail technical developments but refer the reader to the appropriate references.
235 citations
TL;DR: In this paper, a search for neutrinos from neutralino annihilations in the Sun has been performed with the IceCube 22-string neutrino detector using data collected in 1043 days of live time in 2007 No excess over the expected atmospheric background has been observed.
Abstract: A search for muon neutrinos from neutralino annihilations in the Sun has been performed with the IceCube 22-string neutrino detector using data collected in 1043 days of live time in 2007 No excess over the expected atmospheric background has been observed Upper limits have been obtained on the annihilation rate of captured neutralinos in the Sun and converted to limits on the weakly interacting massive particle (WIMP) proton cross sections for WIMP masses in the range 250-5000 GeV These results are the most stringent limits to date on neutralino annihilation in the Sun
184 citations
TL;DR: Depending on the feed composition, CO( 2) and H(2)S may be removed over TRI-PE-MCM-41 simultaneously or sequentially, suitable for acid gas separation from CH(4)-containing mixtures such as natural gas and biogas.
Abstract: Triamine-grafted pore-expanded mesoporous silica (TRI-PE-MCM-41) exhibited high CO2 and H2S adsorption capacity as well as high selectivity toward acid gases versus CH4. Unlike physical adsorbents such as zeolites and activated carbons, the presence of moisture in the feed enhanced the CO2 removal capability of TRI-PE-MCM-41 without altering its H2S adsorption capacity. Thus, depending on the feed composition, CO2 and H2S may be removed over TRI-PE-MCM-41 simultaneously or sequentially. These findings are suitable for acid gas separation from CH4-containing mixtures such as natural gas and biogas.
168 citations
TL;DR: The calculations reported here indicate that for conjugated polymers like those in the PPV family, these conformational subunits electronically couple to neighboring subunits, forming subtly delocalized collective states of nanoscale excitons that determine the polymer optical properties.
Abstract: We report combined experimental and theoretical studies of excitation relaxation in poly[2-methoxy,5-(2′-ethyl-hexoxy)-1,4-phenylenevinylene] (MEH-PPV), oligophenylenevinylene (OPV) molecules of varying length, and model PPV chains. We build on the paradigm that the basic characteristics of conjugated polymers are decided by conformational subunits defined by conjugation breaks caused by torsional disorder along the chain. The calculations reported here indicate that for conjugated polymers like those in the PPV family, these conformational subunits electronically couple to neighboring subunits, forming subtly delocalized collective states of nanoscale excitons that determine the polymer optical properties. We find that relaxation among these exciton states can lead to a decay of anisotropy on ultrafast time scales. Unlike in Forster energy transfer, the exciton does not necessarily translate over a large distance. Nonetheless, the disorder in the polymer chain means that even small changes in the exciton...
152 citations
TL;DR: In this article, a nanocomposite sample was prepared by melt mixing a high density polyethylene (HDPE) with an in situ polymerized HDPE/multi wall carbon nanotube (MWNT) masterbatch.
Abstract: A nanocomposite sample was prepared by melt mixing a high density polyethylene (HDPE) with an in situ polymerized HDPE/multi wall carbon nanotube (MWNT) masterbatch. The nanocomposite had an approximate content of 0.52 wt % MWNT. Rheological, thermal, and mechanical properties were investigated for both neat HDPE and nanocomposite. The nanocomposite, when compared to the neat polymer, exhibits lower values of viscosity, shear modulus and shear stress in extrusion and a concurrent delay of the distortion regimes to higher shear stresses and rates. The nanocomposite presents also improved dimensional stability after processing, and lower values of the melt strength, draw ratio and viscosity in elongational flow. This behavior has been observed in composites in which an adsorption of a fraction (that with the highest molecular weight or relaxation time) of the polymer chains is considered. Furthermore, the enhancement in the crystallization kinetics, probed by rheometry and DSC, suggests that the carbon nano...
151 citations
TL;DR: Sleep neuronal functional networks in depressed patients are characterized by a functional reorganization with a lower mean level of global synchronization and loss of SWN characteristics, providing further support that sleep functional brain networks exhibit “small‐world” properties.
Abstract: Recent evidence suggests that problems in information processing within neural networks may underlie depressive disease. In this study, we investigated whether sleep functional brain networks are abnormally organized during a major depressive episode (MDE). We characterized spatial patterns of functional connectivity by computing the "synchronization likelihood" (SL) of 19 sleep EEG channels in 11 acutely depressed patients [42 (20-51) years] and 14 healthy controls [32.9 (27-42) years]. To test whether disrupting an optimal pattern ["small-world network" (SWN)] of functional brain connectivity underlies MDE, graph theoretical measures were then applied to the resulting synchronization matrices, and a clustering coefficient (C, measure of local connectedness) and a shortest path length (L, measure of overall network integration) were determined. In the depressed group, the mean SL was lower in the delta, theta and sigma frequency bands. Acutely depressed patients showed a significantly lower path length in the theta and delta frequency bands, whereas the cluster coefficient showed no significant changes. The present study provides further support that sleep functional brain networks exhibit "small-world" properties. Sleep neuronal functional networks in depressed patients are characterized by a functional reorganization with a lower mean level of global synchronization and loss of SWN characteristics. These results argue for considering an MDE as a problem of neuronal network organization and a problem of information processing.
138 citations
119 citations
TL;DR: The spectrum from the black hole X-ray transient GRO J1655-40 obtained using the Chandra High Energy Transmission Grating in 2005 is notable for the presence of many lines from odd-Z elements between Na and Co (and Ti and Cr) not previously observed in X-rays as mentioned in this paper.
Abstract: The spectrum from the black hole X-ray transient GRO J1655-40 obtained using the Chandra High Energy Transmission Grating in 2005 is notable as a laboratory for the study of warm absorbers, and for the presence of many lines from odd-Z elements between Na and Co (and Ti and Cr) not previously observed in X-rays. We present synthetic spectral models which can be used to constrain these element abundances and other parameters describing the outflow from the warm absorber in this object. We present results of fitting to the spectrum using various tools and techniques, including automated line fitting, phenomenological models, and photoionization modeling. We show that the behavior of the curves of growth of lines from H-like and Li-like ions indicate that the lines are either saturated or affected by filling-in from scattered or a partially covered continuum source. We confirm the conclusion of previous work by Miller et al., which shows that the ionization conditions are not consistent with wind driving due to thermal expansion. The spectrum provides the opportunity to measure abundances for several elements not typically observable in the X-ray band. These show a pattern of enhancement for iron peak elements, and solar or subsolar values for elements lighter than calcium. Models show that this is consistent with enrichment by a core-collapse supernova. We discuss the implications of these values for the evolutionary history of this system.
113 citations
TL;DR: The data demonstrate that HSF1 is a maternal transcription factor essential for normal progression of meiosis, and shows that CDK1 and MAPK, key meiotic kinases, were significantly disturbed.
110 citations
TL;DR: The authors' data demonstrate defects in NMDA-receptor function and learning dependent signaling cascades in vivo in APP[V717I] transgenic mice and point to decreased surface expression of NMda-receptors as a mechanism involved in early synaptic defects in APP,[V7 17I]transgenic mice in vivo.
03 Jan 2009
TL;DR: The alternating-time temporal logics ATL and ATL * are extended with strategy contexts and memory constraints : the first extension makes strategy quantifiers to not "forget" the strategies being executed by the other players and the second extension allows strategy quantifier to restrict to memoryless or bounded-memory strategies.
Abstract: We extend the alternating-time temporal logics ATL and ATL * with strategy contexts and memory constraints : the first extension makes strategy quantifiers to not "forget" the strategies being executed by the other players. The second extension allows strategy quantifiers to restrict to memoryless or bounded-memory strategies.
We first consider expressiveness issues. We show that our logics can express important properties such as equilibria, and we formally compare them with other similar formalisms ( ATL , ATL *, Game Logic, Strategy Logic, ...). We then address the problem of model-checking for our logics, especially we provide a PSPACE algorithm for the sublogics involving only memoryless strategies and an EXPSPACE algorithm for the bounded-memory case.
TL;DR: A mechanism for the hierarchical self-assembly of this class of materials is proposed based on experimental results and molecular modelling calculations, which allows the creation of white-light-emitting gels.
Abstract: Five fluorene-based co-oligomers have been prepared to study their self-assembly in a wide range of concentrations, from dilute solutions to the solid state. Subtle changes to the chemical structures, introduced to tune the emission colours over the entire visible range, induce strong differences in aggregation behaviour. Only two of the fluorescent co-oligomer derivatives self-assemble to form soluble fibrils from which fluorescent organogels emerge at higher concentrations. In contrast, the other compounds form precipitates. Mixed fluorescent co-oligomer systems exhibit partial energy transfer, which allows the creation of white-light-emitting gels. Finally, a mechanism for the hierarchical self-assembly of this class of materials is proposed based on experimental results and molecular modelling calculations.
TL;DR: In this article, a model for exciton hopping in an energetically disordered molecular landscape is presented, which is parameterized against atomistic and lattice Monte Carlo simulations based on quantum-chemical calculations.
Abstract: We implement a simple, continuous, analytical model for exciton hopping in an energetically disordered molecular landscape. The model is parameterized against atomistic and lattice Monte Carlo simulations based on quantum-chemical calculations. It captures the essential physics of exciton diffusion in disordered media at different temperatures and yields a universal scaling law of the diffusion length with the dimensionless disorder parameter given by the ratio of the energetic disorder width to the thermal energy.
TL;DR: In this paper, the synthesis and characterization of solution processable donor-acceptor-donor (D-A-D) based conjugated molecules with varying ratios of thiophene as donor and benzothiadiazole as acceptor (A) are reported.
Abstract: The synthesis and characterization of solution processable donor–acceptor–donor (D–A–D) based conjugated molecules with varying ratios of thiophene as donor (D) and benzothiadiazole as acceptor (A) are reported. Optical, electrochemical, thermal, morphological and organic thin film transistor (OTFT) device properties of these materials were investigated. The thermal and polarized optical microscope analysis indicates that the materials having higher D/A ratios exhibit both liquid crystalline (LC) and OTFT behavior. AFM analysis of the materials having D/A ratios of 3 and 4 (3T1B and 4T1B) show well ordered structures, resulting from strong π–π interchain interactions compared to the other molecules in this study. A XRD patterns for 3T1B and 4T1B thin films also shows high crystalline ordering. Solution processed OTFTs of 3T1B and 4T1B have shown un-optimized charge carrier mobilities of 2 × 10−2 cm2V−1 s−1 and 4 × 10−3 cm2V−1 s−1, respectively on bare Si/SiO2 substrate.
Proceedings Article•
01 Jan 2009TL;DR: In this paper, an adaptation of the Deterministic plus Stochastic Model (DSM) for the residual is proposed, where the excitation is divided into two distinct spectral bands delimited by the maximum voiced frequency.
Abstract: Speech generated by parametric synthesizers generally suffers from a typical buzziness, similar to what was encountered in old LPC-like vocoders. In order to alleviate this problem, a more suited modeling of the excitation should be adopted. For this, we hereby propose an adaptation of the Deterministic plus Stochastic Model (DSM) for the residual. In this model, the excitation is divided into two distinct spectral bands delimited by the maximum voiced frequency. The deterministic part concerns the low-frequency contents and consists of a decomposition of pitch-synchronous residual frames on an orthonormal basis obtained by Principal Component Analysis. The stochastic component is a high-pass filtered noise whose time structure is modulated by an energy-envelope, similarly to what is done in the Harmonic plus Noise Model (HNM). The proposed residual model is integrated within a HMM-based speech synthesizer and is compared to the traditional excitation through a subjective test. Results show a significative improvement for both male and female voices. In addition the proposed model requires few computational load and memory, which is essential for its integration in commercial applications. Index Terms: HMM-based speech synthesis, residual modeling, Deterministic plus Stochastic model
TL;DR: In this paper, the authors present new spreading-drop data obtained over four orders of time and apply their new analysis tool G-Dyna to demonstrate the specific range over which the various models of dynamic wetting would seem to apply for their experimental system.
Abstract: We present new spreading-drop data obtained over four orders of time and apply our new analysis tool G-Dyna to demonstrate the specific range over which the various models of dynamic wetting would seem to apply for our experimental system. We follow the contact angle and radius dynamics of four liquids on the smooth silica surface of silicon wafers or PET from the first milliseconds to several seconds. Analysis of the images allows us to make several hundred contact angle and droplet radius measurements with great accuracy. The G-Dyna software is then used to fit the data to the relevant theory (hydrodynamic, molecular-kinetic theory, Petrov and De Ruijter combined models, and Shikhmurzaev’s formula). The distributions, correlations, and average values of the free parameters are analyzed and it is shown that for the systems studied even with very good data and a robust fitting procedure, it may be difficult to make reliable claims as to the model which best describes results for a given system. This concl...
TL;DR: The chemical routes for synthesis of iron oxide nanoparticles, the fluid stabilization, and the surface modification of superparamagneticIron oxide particles currently find promising applications in the biomedical field mainly as MRI negative contrast agents.
Abstract: Superparamagnetic iron oxide nanoparticles can be used for numerous applications such as MRI contrast enhancement, hyperthermia, detoxification of biological fluids, drug delivery, or cell separation. In this work, we will summarize the chemical routes for synthesis of iron oxide nanoparticles, the fluid stabilization, and the surface modification of superparamagnetic iron oxide nanoparticles. Some examples of the numerous applications of these particles in the biomedical field mainly as MRI negative contrast agents for tissue-specific imaging, cellular labeling, and molecular imaging will be given. Larger particles or particles displaying a non-neutral surface (thanks to their coating or to a cell transfection agent with which they are mixed) are very useful tools, although the cells to be labeled have no professional phagocytic function. Labeled cells can then be transplanted and monitored by MRI in a broad spectrum of applications. Direct in vivo magnetic labeling of cells is mainly performed by intravenous injection of long-circulating iron oxide-based MRI contrast agents, which can extravasate and/or undergo a cellular uptake in an amount sufficient to allow an MRI visualization of areas of interest such as inflamed regions or tumors. Particles with long circulation times, or able to induce a strong negative effect individually have been also modified by conjugation to a ligand, so that their cellular uptake, or at least their binding to the cell surface, could occur through a specific ligand-receptor interaction, in vivo as well as in vitro. Thus, experimentally as well as in a few trials on humans, iron oxide particles currently find promising applications.
TL;DR: Interaction between changes in cardiac autonomic activity and delta power is altered in chronic primary insomniac patients, even in the absence of modifications in heart rate variability and cardiovascular diseases.
TL;DR: The in vivo MRI studies performed at 4.7 T provide proof of concept that apoptosis-related pathologies could be diagnosed by MRI with a low molecular weight paramagnetic agent.
Abstract: Molecular and cellular imaging of atherosclerosis has garnered more interest at the beginning of the 21st century, with aims to image in vivo biological properties of plaque lesions. Apoptosis seems an attractive target for the diagnosis of vulnerable atherosclerotic plaques prone to a thrombotic event. The aim of the present work was to screen for apoptosis peptide binders by phage display with the final purpose to detect apoptotic cells in atherosclerotic plaques by magnetic resonance imaging (MRI). A phosphatidylserine-specific peptide identified by phage display was thus used to design an MRI contrast agent (CA), which was evaluated as a potential in vivo reporter of apoptotic cells. A library of linear 6-mer random peptides was screened in vitro against immobilized phosphatidylserine. Phage DNA was isolated and sequenced, and the affinity of peptides for phosphatidylserine was evaluated by enzyme-linked immunosorbent assay. The phosphatidylserine-specific peptide and its scrambled homologue were attached to a linker and conjugated to DTPA-isothiocyanate. The products were purified by dialysis and by column chromatography and complexed with gadolinium chloride. After their evaluation using apoptotic cells and a mouse model of liver apoptosis, the phosphatidylserine-targeted CA was used to image atherosclerotic lesions on ApoE(-/-) transgenic mice. Apoptotic cells were detected on liver and aorta specimens by the immunostaining of phosphatidylserine and of active caspase-3. Sequencing of the phage genome highlighted nine different peptides. Their alignment with amino acid sequences of relevant proteins revealed a frequent homology with Ca2+ channels, reminiscent of the function of annexins. Alignment with molecules involved in apoptosis provides a direct correlation between peptide selection and utility. The in vivo MRI studies performed at 4.7 T provide proof of concept that apoptosis-related pathologies could be diagnosed by MRI with a low molecular weight paramagnetic agent. The new CA could have real potential in the diagnosis and therapy monitoring of atherosclerotic disease and of other apoptosis-associated pathologies, such as cancer, ischemia, chronic inflammation, autoimmune disorders, transplant rejection, neurodegenerative disorders, and diabetes mellitus. The phage display-derived peptide could also play a potential therapeutic role through anticoagulant activity by mimicking the role of annexin V, the endogenous ligand of phosphatidylserine.
TL;DR: The AMANDA-II detector has accumulated a large sample of atmospheric muon neutrinos in the 100 GeV to 10 TeV energy range, and the zenith angle and energy distribution of these events can be used to search for various phenomenological signatures of quantum gravity in the neutrino sector, such as violation of Lorentz invariance or quantum decoherence.
Abstract: The AMANDA-II detector, operating since 2000 in the deep ice at the geographic South Pole, has accumulated a large sample of atmospheric muon neutrinos in the 100 GeV to 10 TeV energy range. The zenith angle and energy distribution of these events can be used to search for various phenomenological signatures of quantum gravity in the neutrino sector, such as violation of Lorentz invariance or quantum decoherence. Analyzing a set of 5511 candidate neutrino events collected during 1387 days of livetime from 2000 to 2006, we find no evidence for such effects and set upper limits on violation of Lorentz invariance and quantum decoherence parameters using a maximum likelihood method. Given the absence of evidence for new flavor-changing physics, we use the same methodology to determine the conventional atmospheric muon neutrino flux above 100 GeV.
TL;DR: Changes in estradiol and, to a lesser extent, in FSH levels are associated with an increased risk of depressive symptoms in postmenopausal women, further support a role for fluctuating rather than absolute hormone levels in depression in later life.
Abstract: Objective Across a woman's lifetime, variations in hormone levels are known to influence mood and well-being. Whether absolute or changes in hormone levels over time are associated with depression among postmenopausal women remains unclear. Methods The Melbourne Women's Midlife Health Project is a longitudinal population-based study of women who were followed through the menopausal transition. This analysis is based on data collected from 138 postmenopausal women in years 11 and 13 of the study, who were assessed for the presence of depressive symptoms using the Center for Epidemiological Studies Depression Scale. Logistic regression models were developed to determine whether absolute or changes in hormone levels were associated with depression. Results No significant associations were found between depressive symptoms and the absolute levels of sex hormone-binding globulin, testosterone, free androgen index, estradiol, free estradiol, or follicle-stimulating hormone (FSH). On the other hand, women with a decline in total serum estradiol over the 2-year period had a more than threefold increased risk of depressive symptoms (odds ratio, 3.5; 95% CI, 1.2-9.9). A large increase in FSH levels over this period was also associated with depressive symptoms (odds ratio, 2.6; 95% CI, 1.0-6.7). These associations remained even after adjustment for initial depression score, as well as a range of potential confounding factors. Conclusions Changes in estradiol and, to a lesser extent, in FSH levels are associated with an increased risk of depressive symptoms in postmenopausal women. These results further support a role for fluctuating rather than absolute hormone levels in depression in later life.
TL;DR: A molecular model system of tetraphenyl porphyrins adsorbed on metallic substrates is systematically investigated within a joint scanning tunnelling microscopy/molecular modelling approach, indicating a subtle interplay between different contributions.
Abstract: A molecular model system of tetraphenyl porphyrins (TPP) adsorbed on metallic substrates is systematically investigated within a joint scanning tunnelling microscopy/molecular modelling approach. The molecular conformation of TPP molecules, their adsorption on a gold surface and the growth of highly ordered TPP islands are modelled with a combination of density functional theory and dynamic force field methods. The results indicate a subtle interplay between different contributions. The molecule–substrate interaction causes a bending of the porphyrin core which also determines the relative orientations of phenyl legs attached to the core. A major consequence of this is a characteristic (and energetically most favourable) arrangement of molecules within self-assembled molecular clusters; the phenyl legs of adjacent molecules are not aligned parallel to each other (often denoted as π–π stacking) but perpendicularly in a T-shaped arrangement. The results of the simulations are fully consistent with the scanning tunnelling microscopy observations, in terms of the symmetries of individual molecules, orientation and relative alignment of molecules in the self-assembled clusters.
TL;DR: Several convenient methods aiming at the quantification of iron from iron oxide nanoparticle-containing samples are presented.
Abstract: Iron oxide (nano)particles are powerful contrast agents for MRI and tags for magnetic cellular labeling. The need for quantitative methods to evaluate the iron content of contrast media solutions and biological matrixes is thus obvious. Several convenient methods aiming at the quantification of iron from iron oxide nanoparticle-containing samples are presented. Copyright © 2009 John Wiley & Sons, Ltd.
29 Apr 2009
TL;DR: This report summarises the different presentations, the MDE challenges identified by the workshop participants, and the discussions of the breakout groups.
Abstract: After more than a decade of research in Model-Driven Engineering (MDE), the state-of-the-art and the state-of-the-practice in MDE has significantly progressed. Therefore, during this workshop we raised the question of how to proceed next, and we identified a number of future challenges in the field of MDE. The objective of the workshop was to provide a forum for discussing the future of MDE research and practice. Seven presenters shared their vision on the future challenges in the field of MDE. Four breakout groups discussed scalability, consistency and co-evolution, formal foundations, and industrial adoption, respectively. These themes were identified as major categories of challenges by the participants. This report summarises the different presentations, the MDE challenges identified by the workshop participants, and the discussions of the breakout groups.
TL;DR: In this paper, force field and quantum-chemical calculations are combined to model the packing of pentacene molecules at the atomic level on two polymer dielectric layers (poly(methyl methacrylate) (PMMA) versus polystyrene (PS)) widely used in fleld-effect transistors and assess the impact of electrostatic interactions at the interface on the charge mobility values in the Pentacene layers.
Abstract: Force-field and quantum-chemical calculations are combined to model the packing of pentacene molecules at the atomic level on two polymer dielectric layers (poly(methyl methacrylate) (PMMA) versus polystyrene (PS)) widely used in fleld-effect transistors and to assess the impact of electrostatic interactions at the interface on the charge mobility values in the pentacene layers. The results show unambiguously that the electrostatic interactions introduce a significant energetic disorder in the pentacene layer in contact with the polymer chains; a drop in the hole mobility by a factor of 5 is predicted with PS chains while a factor of 60 is obtained for PM MA due to the presence of polar carbonyl groups.
TL;DR: In this article, primary amine-based plasma polymer films (NH 2 -PPF) were synthesized using plasma polymerization of allylamine in continuous wave (CW) and pulsed radio-frequency (RF) modes.
Abstract: Primary amine-based plasma polymer films (NH 2 -PPF) were synthesized using plasma polymerization of allylamine in continuous wave (CW) and pulsed radio-frequency (RF) modes. Plasma chemistry, studied by residual gas analysis mass spectrometry, revealed that the precursor fragmentation is a function of the equivalent power (P eq ) dissipated in the discharge, independently of the plasma mode used. X-ray photoelectron spectroscopy combined with time-of-flight secondary ion mass spectrometry suggests as the precursor fragmentation in the plasma increases: (i) a decrease of the primary amine concentration in the NH 2 -PPF (%NH 2 ) and (ii) an increase of the cross-linking degree. For a given P eq , similar to the precursor fragmentation in the plasma, the NH 2 -PPF characteristics were found to be independent of the plasma mode used. Therefore, the main advantage of using pulsed RF processes over CW ones is the possibility to work at very low P eq which enables low precursor fragmentation, optimization of %NH 2 , and reduction of the film cross-linking degree. The chemical composition and the cross-linking degree of the NH 2 -PPF synthesized by allylamine plasma polymerization can thus be tailored by adjusting the equivalent RF power injected in the plasma.
TL;DR: The pbrB∷Tn(Km2) mutation resulted in the most significant decrease of Pb(II) resistance, indicating that Pb (II) sequestration, avoiding re-entry of this toxic metal ion, forms a critical step in the pbr-encoded P b( II) resistance mechanism.
Abstract: Proteome and transcriptome analysis, combined with mutagenesis, were used to better understand the response of Cupriavidus metallidurans CH34 against lead(II). Structural Pb(II)-resistance genes of the pMOL30-encoded pbrUTRABCD operon formed the major line of defense against Pb(II). However, several general stress response mechanisms under the control of alternative sigma factors such as sigma24/rpoK, sigma32/rpoH and sigma28/fliA were also induced. In addition, the expression of the pbrR(2) cadA pbrC(2) operon of the CMGI-1 region and the chromosomally encoded zntA were clearly induced in the presence of Pb(II), although their respective gene products were not detected via proteomics. After inactivation of the pbrA, pbrB or pbrD genes, the expression of the pbrR(2) cadA pbrC(2) operon went up considerably. This points towards synergistic interactions between pbrUTRABCD and pbrR(2) cadA pbrC(2) to maintain a low intracellular Pb(II) concentration, where pbrR(2) cadA pbrC(2) gene functions can complement and compensate for the mutations in the pbrA and pbrD genes. This role of zntA and cadA to complement for the loss of pbrA was further confirmed by mutation analysis. The pbrB:: colonsTn(Km2) mutation resulted in the most significant decrease of Pb(II) resistance, indicating that Pb(II) sequestration, avoiding re-entry of this toxic metal ion, forms a critical step in the pbr-encoded Pb(II) resistance mechanism.
TL;DR: The goal is to characterize the amplitudes of the room-temperature molecular displacements and the corresponding thermal fluctuations in electronic transfer integrals, which constitute a key parameter for charge transport in organic semiconductors.
Abstract: We have performed classical molecular dynamics simulations and quantum-chemical calculations on molecular crystals of anthracene and perfluoropentacene. Our goal is to characterize the amplitudes of the room-temperature molecular displacements and the corresponding thermal fluctuations in electronic transfer integrals, which constitute a key parameter for charge transport in organic semiconductors. Our calculations show that the thermal fluctuations lead to Gaussian-like distributions of the transfer integrals centered around the values obtained for the equilibrium crystal geometry. The calculated distributions have been plugged into Monte-Carlo simulations of hopping transport, which show that lattice vibrations impact charge transport properties to various degrees depending on the actual crystal structure.
06 Jun 2009
TL;DR: An incremental inconsistency checker based on the idea of representing models as sequences of primitive construction operations can be computed to analyze and reduce the number of rules that need to be re-checked during a model increment.
Abstract: Due to the increasing use of models, and the inevitable model inconsistencies that arise during model-based software development and evolution, model inconsistency detection is gaining more and more attention. Inconsistency checkers typically analyze entire models to detect undesired structures as defined by inconsistency rules. The larger the models become, the more time the inconsistency detection process takes. Taking into account model evolution, one can significantly reduce this time by providing an incremental checker. In this article we propose an incremental inconsistency checker based on the idea of representing models as sequences of primitive construction operations. The impact of these operations on the inconsistency rules can be computed to analyze and reduce the number of rules that need to be re-checked during a model increment.