Last 7 days     Results 1761-1780 of 43832.   84 85 86 87 88 89 90 91 92 93 94   Ni-Cu/SiO2 cogelled xerogel catalysts for selective hydrodechlorination of 1,2-dichloroethane into ethyleneLambert, Stéphanie Conference (2015, August 13)Hydrodechlorination of chlorinated organics is a particularly attractive alternative compared with incineration of wastes from the chlorine industry from both economic and environmental points of view ... [more ▼]Hydrodechlorination of chlorinated organics is a particularly attractive alternative compared with incineration of wastes from the chlorine industry from both economic and environmental points of view. Several authors demonstrated the ability of bimetallic catalysts, composed of metals from Groups VIII and IB, to convert chlorinated alkanes selectively into less or not chlorinated alkenes. The purpose of this study is to measure catalytic activity and selectivities of 1,2-dichloroethane hydrodechlorination over Ni-Cu/SiO2 cogelled xerogel catalysts and to study relationships between catalytic activity and surface properties of bimetallic catalysts. To understand the mechanism of hydrodechlorination of 1,2-dichloroethane on a supported alloy, the surface composition of Ni-Cu alloy is measured from H2 chemisorption, XRD and TEM. Values obtained indicate a very pronounced surface enrichment with copper. Samples containing various amounts of nickel and copper are xerogels prepared by a one-step sol-gel procedure, which consists in the cogelation of the silica precursor, tetraethoxysilane (TEOS), with organically substituted alkoxides capable of forming chelates with nickel and copper ions. The resulting alcogels were dried under vacuum at 80°C, calcined in air at 400°C, and finally reduced in hydrogen at 450°C. For each catalytic experiment, 0.11 g of catalyst pellets were tested. The temperature was successively kept at 200, 250, 300, 350 and 300°C. While 1,2-dichloroethane hydrodechlorination over pure nickel mainly produces ethane, increasing copper content in bimetallic catalysts results in an increase in ethylene selectivity. Used alone, copper deactivates rapidly due to their covering by chlorine atoms. When nickel is present, it supplies hydrogen atoms for the regeneration of the chlorinated copper surfaces into metallic copper. The specific consumption rate of 1,2-dichloroethane decreases when copper loading increases. The turnover frequency, that is, the number of catalytic cycle per active site (nickel atom and its surrounding copper atoms) and per second, seems to be independent of surface composition of alloy particles. [less ▲]Detailed reference viewed: 19 (0 ULg) All Poly(ionic liquid)-based block copolymers by sequential controlled radical copolymerization of vinylimidazolium monomersCordella, Daniela ; Kermagoret, Anthony; Debuigne, Antoine et alin Macromolecules (2015), 48(15), 5230-5243The organometallic-mediated radical polymerization (OMRP) of N-vinyl-3-alkylimidazolium-type monomers, featuring the bis(trifluoromethylsulfonyl)imide counteranion (Tf2N–), in the presence of Co(acac)2 as ... [more ▼]The organometallic-mediated radical polymerization (OMRP) of N-vinyl-3-alkylimidazolium-type monomers, featuring the bis(trifluoromethylsulfonyl)imide counteranion (Tf2N–), in the presence of Co(acac)2 as controlling agent, is reported. Polymerizations of monomers with methyl, ethyl, and butyl substituents are fast, reaching high monomer conversion in ethyl acetate as solvent at 30 °C, and afford structurally well-defined hydrophobic poly(ionic liquid)s (PILs) of N-vinyl type. Block copolymer synthesis is also achieved by sequential OMRP of N-vinyl-3-alkylimidazolium salts carrying different alkyl chains and different counteranions (Tf2N– or Br–). These block copolymerizations are carried out at 30 °C, either under homogeneous solution in methanol or in a biphasic medium consisting of a mixture of ethyl acetate and water. Unprecedented PIL-b-PIL block copolymers are thus prepared under these conditions. However, anion exchange occurs at the early stage of the growth of the second block. Finally, diblock copolymers generated in the biphasic medium can be readily coupled by addition of isoprene, forming all PIL-based and symmetrical ABA-type triblock copolymers in a one-pot process. Such a direct block copolymerization method, involving vinylimidazolium monomers bearing different alkyl chains, thus opens new opportunities in the precision synthesis of all PIL-based block copolymers of tunable properties. [less ▲]Detailed reference viewed: 19 (2 ULg) Interlaboratory study to evaluate the robustness of capillary electrophoresis-mass spectrometry for peptide mappingWenz, Christian; Barbas, Coral; Lopez-Gonzalvez, Angeles et alin Journal of Separation Science (2015)A collaborative study on the robustness and portability of a capillary electrophoresis-mass spectrometry method for peptide mapping was performed by an international team, consisting of 13 independent ... [more ▼]A collaborative study on the robustness and portability of a capillary electrophoresis-mass spectrometry method for peptide mapping was performed by an international team, consisting of 13 independent laboratories from academia and industry. All participants used the same batch of samples, reagents and coated capillaries to run their assays, whereas they utilized the capillary electrophoresis-mass spectrometry equipment available in their laboratories. The equipment used varied in model, type and instrument manufacturer. Furthermore, different types of sheath-flow capillary electrophoresis–mass spectrometry interfaces were used. Migration time, peak height and peak area of ten representative target peptides of trypsin-digested bovine serum albumin were determined by every laboratory on two consecutive days. The data were critically evaluated to identify outliers and final values for means, repeatability (precision within a laboratory) and reproducibility (precision between laboratories) were established. For relative migration time the repeatability was between 0.05 and 0.18% RSD and the reproducibility between 0.14 and 1.3% RSD. For relative peak area repeatability and reproducibility values obtained were 3–12 and 9–29% RSD, respectively. These results demonstrate that capillary electrophoresis-mass spectrometry is robust enough to allow a method transfer across multiple laboratories and should promote a more widespread use of peptide mapping and other capillary electrophoresis-mass spectrometry applications in biopharmaceutical analysis and related fields. [less ▲]Detailed reference viewed: 28 (1 ULg) The evolution of metal hyperaccumulation in Arabidopsis halleriHanikenne, Marc Scientific conference (2015, August 07)Detailed reference viewed: 23 (1 ULg) Recent changes in north-west Greenland climate documented by NEEM shallow ice core data and simulations, and implications for past-temperature reconstructionsMasson-Delmotte, V.; Steen-Larsen, H.; Ortega, P. et alin Cryosphere (The) (2015), 9Combined records of snow accumulation rate, δ18O and deuterium excess were produced from several shallow ice cores and snow pits at NEEM (North Greenland Eemian Ice Drilling), covering the period from ... [more ▼]Combined records of snow accumulation rate, δ18O and deuterium excess were produced from several shallow ice cores and snow pits at NEEM (North Greenland Eemian Ice Drilling), covering the period from 1724 to 2007. They are used to investigate recent climate variability and characterise the isotope–temperature relationship. We find that NEEM records are only weakly affected by inter-annual changes in the North Atlantic Oscillation. Decadal δ18O and accumulation variability is related to North Atlantic sea surface temperature and is enhanced at the beginning of the 19th century. No long-term trend is observed in the accumulation record. By contrast, NEEM δ18O shows multidecadal increasing trends in the late 19th century and since the 1980s. The strongest annual positive δ18O values are recorded at NEEM in 1928 and 2010, while maximum accumulation occurs in 1933. The last decade is the most enriched in δ18O (warmest), while the 11-year periods with the strongest depletion (coldest) are depicted at NEEM in 1815–1825 and 1836–1846, which are also the driest 11-year periods. The NEEM accumulation and δ18O records are strongly correlated with outputs from atmospheric models, nudged to atmospheric reanalyses. Best performance is observed for ERA reanalyses. Gridded temperature reconstructions, instrumental data and model outputs at NEEM are used to estimate the multidecadal accumulation–temperature and δ18O–temperature relationships for the strong warming period in 1979–2007. The accumulation sensitivity to temperature is estimated at 11 ± 2 % °C−1 and the δ18O–temperature slope at 1.1 ± 0.2 ‰ °C−1, about twice as large as previously used to estimate last interglacial temperature change from the bottom part of the NEEM deep ice core. [less ▲]Detailed reference viewed: 33 (1 ULg) Depression in Women and in Men: Differences on Behavioral Avoidance and on Behavioral ActivationWagener, Aurélie ; Baeyens, Céline; Blairy, Sylvie Poster (2015, August 06)Depression is a well-known disorder characterized by e.g. sadness, loss of interest and pleasure, feelings of guilt or worthlessness. Depression is also characterized by a decrease of the level of ... [more ▼]Depression is a well-known disorder characterized by e.g. sadness, loss of interest and pleasure, feelings of guilt or worthlessness. Depression is also characterized by a decrease of the level of engagement in activities also conceptualized as behavioral avoidance. Indeed, depressed patients less and less engage themselves in pleasurable activities (e.g. they spend more and more time in their bed, see their friends more rarely). Reciprocally, this decrease of the level of engagement in activities reinforces and maintains depressive symptoms. This relationship between depression and a low level of engagement in activities is well-established in the scientific literature but no study has, until now, discussed the reasons of this decrease of engagement in activities. According to theoretical models of depression (Beck, 2008; Lewinsohn, 1985; Watkins, 2009), five sets of psychological processes (PP) are involved in depressive symptomatology: negative repetitive thoughts, maladaptive emotion regulation strategies, low environmental rewards, negative self-image and inhibition. We hypothesize that these PP could be considered as explaining factors of the behavioral avoidance. Furthermore, we hypothesize that other PP could be considered as explaining factors of the behavioral activation (adaptive emotion regulation strategies, high environmental rewards, positive self-image, approach and high self-clarity). Then, our aim is to assess the links between behavioral avoidance as well as activation and the PP mentioned above. In order to reach this objective, we developed a model of these links based on the psychological model of mental ill-health of Kinderman (2005, 2013). According to this model, biological, social and circumstantial factors lead to mental disorders through their conjoint effects on psychological processes. Furthermore, because depression is different in women and in men, we assessed the adequacy of our model according to the sex. Clinical and community adults completed an online survey assessing the psychological processes mentioned above, avoidance and activation. Since several questionnaires were used to assess each PP, factorial scores were computed for each one. Preliminary analyses (confirmatory factor analyses) were realized with a sample of 393 women and 139 men. The results revealed differences between men and women. For women, on the one hand, low levels of environmental rewards, maladaptive emotion regulation strategies and negative repetitive thoughts are linked to behavioral avoidance, and on the other hand, high levels of environmental rewards and positive self-image are linked to behavioral activation. For men, on the one hand, negative self-image, maladaptive emotion regulation strategies and low environmental rewards are linked to behavioral avoidance, and, on the other hand, high levels of environmental rewards and positive self-image are linked to behavioral activation. The final results will be presented during the convention, as data-collection is on-going and will end in May 2015. Clinical implications of these results will also be discussed such as the relevance of working on the levels of environmental rewards. [less ▲]Detailed reference viewed: 44 (2 ULg) A principle of similarity for nonlinear vibration absorbersHabib, Giuseppe ; Kerschen, Gaëtan Conference (2015, August 05)With continual interest in expanding the performance envelope of engineering systems, nonlinear components are increasingly utilized in real-world applications. This causes the failure of wellestablished ... [more ▼]With continual interest in expanding the performance envelope of engineering systems, nonlinear components are increasingly utilized in real-world applications. This causes the failure of wellestablished techniques to mitigate resonant vibrations. In particular, this holds for the linear tuned vibration absorber (LTVA), which requires an accurate tuning of its natural frequency to the resonant vibration frequency of interest. This is why the nonlinear tuned vibration absorber (NLTVA), the nonlinear counterpart of the LTVA, has been recently developed. An unconventional aspect of this absorber is that its restoring force is tailored according to the nonlinear restoring force of the primary system. This allows the NLTVA to extend the so-called Den Hartog’s equal-peak rule to the nonlinear range. In this work, a fully analytical procedure, exploiting harmonic balance and perturbation techniques, is developed to define the optimal value of the nonlinear terms of the NLTVA. The developments are such that they can deal with any polynomial nonlinearity in the host structure. Another interesting feature of the NLTVA, discussed in the paper, is that nonlinear terms of different orders do not interact with each other in first approximation, thus they can be treated separately. Numerical results obtained through the shooting method coupled with pseudoarclength continuation validate the analytical developments. [less ▲]Detailed reference viewed: 30 (3 ULg) Alternatives to traditional valorisation ways for brewer’s spent grainsVillani, Nicolas ; Aguedo, Mario ; Richel, Aurore Poster (2015, August 05)Brewer’s Spent Grains (BSG) are a highly available and cheap food supply chain waste (FSCW) that is mainly used in low-valued feed applications. This residue represents around 85 % of the total amount of ... [more ▼]Brewer’s Spent Grains (BSG) are a highly available and cheap food supply chain waste (FSCW) that is mainly used in low-valued feed applications. This residue represents around 85 % of the total amount of waste produced by breweries with an annual tonnage of 3.4 million tons (on a dry basis) in the European Union. Based on its composition, BSG could be valorised in a wide variety of value-added products. For example, cellulose and remaining starch could easily be turned into ethanol or used as solid state fermentation media or as platform molecules for further chemical synthesis. These alternative valorisation ways could lead to an important economic relief through the whole brewery industry. Herein is described a multistep fractionation of BSG into cellulosic pulp, free sugars, proteins, germs and lignin using an Organosolv acidic pretreatment. This extraction procedure has been optimised in order to allow the most efficient and complete valorisation of BSG. [less ▲]Detailed reference viewed: 92 (10 ULg) Evidence of a fine-scale genetic structure for the endangered Pyrenean desman (Galemys pyrenaicus) in the French PyreneesGillet, François ; Cabria Garrido, Maria Teresa; Blanc, Frédéric et alPoster (2015, August 05)Detailed reference viewed: 27 (0 ULg) Jouer avec les mots, pourquoi et comment ?Rigo, Michel Scientific conference (2015, August 04)A l'instar de Raymond Queneau et ses cent mille milliards de poèmes, cet exposé a pour but de compter et de construire des mots aux propriétés parfois surprenantes. Les premiers résultats en combinatoire ... [more ▼]A l'instar de Raymond Queneau et ses cent mille milliards de poèmes, cet exposé a pour but de compter et de construire des mots aux propriétés parfois surprenantes. Les premiers résultats en combinatoire des mots remontent au début du siècle précédent, avec les travaux du mathématicien norvégien Axel Thue. Cette branche des mathématiques étudie la structure et les arrangements apparaissant au sein de suites finies, ou infinies, de symboles appartenant à un ensemble fini. Donnons un exemple rudimentaire. Un carré est la juxtaposition de deux répétitions d'un mot, ainsi "coco" ou "bonbon" sont des carrés. On dira alors qu'un mot comme "taratata" contient un carré. Il est aisé de vérifier que, si on dispose uniquement de deux symboles "a" et "b", alors tout mot de longueur au moins 4 contient un des carrés "aa", "bb", "abab" ou encore "baba". On dira donc que, sur deux symboles, les carrés sont inévitables. Cette observation pose des questions intéressantes et simples à formuler : Avec trois symboles, peut-on construire un mot arbitrairement long ne contenant pas de carré ? Si on se limite à deux symboles, peut-on construire un mot arbitrairement long sans cube, i.e., évitant la juxtaposition de trois répétitions d'un même mot ? En fonction de la taille de l'alphabet, quels motifs doivent nécessairement apparaître et quels sont ceux qui sont évitables ? Que se passe-t-il si on autorise certaines permutations ? etc. Dans cet exposé, on passera en revue quelques constructions simples de mots finis ou infinis : mot de Thue-Morse, mot de Fibonacci, mots Sturmiens. Nous montrerons aussi que les applications sont nombreuses : arithmétique, transcendance en théorie des nombres, informatique mathématique et théorie des automates, pavages du plan, dynamique symbolique et codage de rotations, infographie, géométrie discrète et représentation de segment de droites à l'écran, bio-informatique, ... [less ▲]Detailed reference viewed: 56 (8 ULg) Quadratic reformulations of nonlinear binary optimization problemsAnthony, Martin; Boros, Endre; Crama, Yves et alE-print/Working paper (2015)Very large nonlinear unconstrained binary optimization problems arise in a broad array of applications. Several exact or heuristic techniques have proved quite successful for solving many of these ... [more ▼]Very large nonlinear unconstrained binary optimization problems arise in a broad array of applications. Several exact or heuristic techniques have proved quite successful for solving many of these problems when the objective function is a quadratic polynomial. However, no similarly efficient methods are available for the higher degree case. Since high degree objectives are becoming increasingly important in certain application areas, such as computer vision, various techniques have been recently developed to reduce the general case to the quadratic one, at the cost of increasing the number of variables. In this paper we initiate a systematic study of these quadratization approaches. We provide tight lower and upper bounds on the number of auxiliary variables needed in the worst-case for general objective functions, for bounded-degree functions, and for a restricted class of quadratizations. Our upper bounds are constructive, thus yielding new quadratization procedures. Finally, we completely characterize all minimal'' quadratizations of negative monomials. [less ▲]Detailed reference viewed: 62 (3 ULg) A next-generation approach to assess the cyanobacterial diversity and biogeography in the High Arctic (Svalbard)Laughinghouse, Haywood Dail; Stelmach Pessi, Igor ; Velazquez, David et alPoster (2015, August 03)Polar ecosystems are extremely sensitive to global climate changes and human activities. Cyanobacteria are key photosynthetic organisms in these latitudes, due to their roles in soil aggregation, nitrogen ... [more ▼]Polar ecosystems are extremely sensitive to global climate changes and human activities. Cyanobacteria are key photosynthetic organisms in these latitudes, due to their roles in soil aggregation, nitrogen fixation, carbon cycles, and secondary metabolite production, among others. Previous works indicate that different cyanobacterial taxa/communities have different impacts on the environment, in both biogeochemical cycles and bioactive compound productions. Furthermore, the presence of biogeographical patterns in microorganisms, as found in macroorganisms, is an ongoing debate. In this study, during the 2013 MicroFun expedition, we sampled 72 locations around Svalbard including diverse biotopes such as glacial forefields, tundra soils, hot springs, soil crusts, microbial mats, wet walls, cryoconites, plankton and periphyton, in order to (1) assess the biodiversity of cyanobacteria around Svalbard, (2) verify the existence of biogeographical trends around the archipelago, and (3) compare these data with other polar (cold) areas, especially Antarctica. We used a pyrosequencing approach targeting cyanobacteria-specific 16S rRNA gene sequences to deeply study the cyanobacterial communities. [less ▲]Detailed reference viewed: 52 (0 ULg) Development of cryopreservation methods for long-term preservation of cyanobacterial strains in the BCCM/ULC collectionCrahay, Charlotte ; Renard, Marine ; Mari, Maud et alPoster (2015, August 03)Long-term genetic and functional stability is a fundamental requirement for the maintenance of microorganisms and cryopreservation is the preferred method for the long-term storage of many micro-organisms ... [more ▼]Long-term genetic and functional stability is a fundamental requirement for the maintenance of microorganisms and cryopreservation is the preferred method for the long-term storage of many micro-organisms, including cyanobacteria. The BCCM/ULC collection currently holds 200 cyanobacterial strains, but only 62 are cryo-preserved. The main limiting factors are the low levels of survival of some strains and the long periods required to recover from cryopreservation, and thus the inability to deliver rapidly cryopreserved strains to the user community. The devel-opment of improved cryopreservation protocols is therefore required for the future expansion and valorization of the collection. The BRAIN-be project PRESPHOTO (preservation of photosynthetic micro-algae in the BCCM collections) (www.presphoto.ulg.ac.be) aims to improve the preservation of cyanobacterial and diatoms in the BCCM/ULC and BCCM/DCG collections, respectively. [less ▲]Detailed reference viewed: 30 (2 ULg) The BCCM/ULC collection : a Biological Ressource Center for polar cyanobacteriaWilmotte, Annick ; Renard, Marine ; Lara, Yannick et alPoster (2015, August 03)In this study, during the 2013 MicroFun expedition, we sampled 72 locations around Svalbard including diverse biotopes such as glacial forefields, tundra soils, hot springs, soil crusts, microbial mats ... [more ▼]In this study, during the 2013 MicroFun expedition, we sampled 72 locations around Svalbard including diverse biotopes such as glacial forefields, tundra soils, hot springs, soil crusts, microbial mats, wet walls, cryoconites, plankton and periphyton, in order to (1) assess the biodiversity of cyanobacteria around Svalbard, (2) verify the existence of biogeographical trends around the archipelago, and (3) compare these data with other polar (cold) areas, especially Antarctica. We used a pyrosequencing approach targeting cyanobacteria-specific 16S rRNA gene sequences to deeply study the cyanobacterial communities. [less ▲]Detailed reference viewed: 17 (1 ULg) Genome sequencing of an endemic filamentous Antarctic cyanobacteriumLara, Yannick ; Verlaine, Olivier ; Kleinteich, Julia et alPoster (2015, August 03)The strain Phormidium priestleyi ULC007 was isolated from a benthic mat located in a shallow freshwater pond in the Larsemann Hills (69°S), Western Antarctica. This strain belongs to a cyanobacterial ... [more ▼]The strain Phormidium priestleyi ULC007 was isolated from a benthic mat located in a shallow freshwater pond in the Larsemann Hills (69°S), Western Antarctica. This strain belongs to a cyanobacterial cluster that appeared as potentially endemic (Taton et al. 2006). After obtaining an axenic isolate, we sequenced the genome of this strain in the frame of the BELSPO CCAMBIO project, in order to better understand the functioning, metabolism and adaptative strategies of cyanobacteria to the extreme Antarctic environment. [less ▲]Detailed reference viewed: 30 (4 ULg) Contribution of cyanobacteria to the building of travertines in a calcareous streamWilmotte, Annick ; Golubic, Stjepko; Kleinteich, Julia et alPoster (2015, August 03)The ambient temperature travertine deposits of the calcareous Hoyoux River (Modave, Belgium) and several tributaries are organized and promoted by the filamentous cyanobacterium identified by its ... [more ▼]The ambient temperature travertine deposits of the calcareous Hoyoux River (Modave, Belgium) and several tributaries are organized and promoted by the filamentous cyanobacterium identified by its morphotype and ecological properties as Phormidium cf. incrustatum. A combination of techniques was used to study this biotope: physico-chemical parameters and CO2 measurements, Scanning and Transmission Electron Microscopy, RAMAN microspectroscopy. A molecular diversity study with pyrosequencing of the cyanobacterial 16S rRNA is in progress. A potential candidate was isolated in culture. [less ▲]Detailed reference viewed: 33 (1 ULg) A propos des fonctions continues qui ne sont dérivables en aucun pointEsser, Céline Conference (2015, August 03)En 1872, Karl Weierstrass présenta non seulement une, mais toute une famille de fonctions continues et nulle part dérivables. Après la publication de ce résultat, beaucoup d'autres mathématiciens ... [more ▼]En 1872, Karl Weierstrass présenta non seulement une, mais toute une famille de fonctions continues et nulle part dérivables. Après la publication de ce résultat, beaucoup d'autres mathématiciens apportèrent leur propre contribution en construisant d'autres fonctions continues et nulle part dérivables. Dans cet exposé, nous présenterons les fonctions de Weierstrass et nous montrerons que le théorème de Baire permet d'affirmer que l'ensemble des fonctions nulle part dérivables est dense dans l'ensemble des fonctions continues. Nous étudierons également la régularité ponctuelle des fonctions de Weierstrass en introduisant la notion d'exposant de Hölder. [less ▲]Detailed reference viewed: 30 (6 ULg) Time series of high-resolution spectra of SN 2014J observed with the TIGRE telescopeJack, D.; Mittag, M.; Schröder, K.-P. et alin Monthly Notices of the Royal Astronomical Society (2015), 451We present a time series of high-resolution spectra of the Type Ia supernova 2014J, which exploded in the nearby galaxy M82. The spectra were obtained with the HEROS échelle spectrograph installed at the ... [more ▼]We present a time series of high-resolution spectra of the Type Ia supernova 2014J, which exploded in the nearby galaxy M82. The spectra were obtained with the HEROS échelle spectrograph installed at the 1.2-m TIGRE telescope. We present a series of 33 spectra with a resolution of R ≈ 20 000, which covers the important bright phases in the evolution of SN 2014J during the period from 2014 January 24 to April 1. The spectral evolution of SN 2014J is derived empirically. The expansion velocities of the Si II P-Cygni features were measured and show the expected decreasing behaviour, beginning with a high velocity of 14 000 km s[SUP]-1[/SUP] on January 24. The Ca II infrared triplet feature shows a high-velocity component with expansion velocities of >20 000 km s[SUP]-1[/SUP] during the early evolution apart from the normal component showing similar velocities as Si II. Further broad P-Cygni profiles are exhibited by the principal lines of Ca II, Mg II and Fe II. The TIGRE SN 2014J spectra also resolve several very sharp Na I D doublet absorption components. Our analysis suggests interesting substructures in the interstellar medium of the host galaxy M82, as well as in our Milky Way, confirming other work on this SN. We were able to identify the interstellar absorption of M82 in the lines of Ca II H & K at 3933 and 3968 Å as well as K I at 7664 and 7698 Å. Furthermore, we confirm several diffuse interstellar bands, at wavelengths of 6196, 6283, 6376, 6379and 6613 Å and give their measured equivalent widths. [less ▲]Detailed reference viewed: 15 (0 ULg) A Coordinated X-Ray and Optical Campaign of the Nearest Massive Eclipsing Binary, δ Orionis Aa. II. X-Ray VariabilityNichols, J.; Huenemoerder, D. P.; Corcoran, M. F. et alin Astrophysical Journal (2015), 809We present time-resolved and phase-resolved variability studies of an extensive X-ray high-resolution spectral data set of the δ Ori Aa binary system. The four observations, obtained with Chandra ACIS ... [more ▼]We present time-resolved and phase-resolved variability studies of an extensive X-ray high-resolution spectral data set of the δ Ori Aa binary system. The four observations, obtained with Chandra ACIS HETGS, have a total exposure time of ≈ 479 ks and provide nearly complete binary phase coverage. Variability of the total X-ray flux in the range of 5–25 Å is confirmed, with a maximum amplitude of about ±15% within a single ≈ 125 ks observation. Periods of 4.76 and 2.04 days are found in the total X-ray flux, as well as an apparent overall increase in the flux level throughout the nine-day observational campaign. Using 40 ks contiguous spectra derived from the original observations, we investigate the variability of emission line parameters and ratios. Several emission lines are shown to be variable, including S xv, Si xiii, and Ne ix. For the first time, variations of the X-ray emission line widths as a function of the binary phase are found in a binary system, with the smallest widths at ϕ = 0.0 when the secondary δ Ori Aa2 is at the inferior conjunction. Using 3D hydrodynamic modeling of the interacting winds, we relate the emission line width variability to the presence of a wind cavity created by a wind–wind collision, which is effectively void of embedded wind shocks and is carved out of the X-ray-producing primary wind, thus producing phase-locked X-ray variability. Based on data from the Chandra X-ray Observatory and the MOST satellite, a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute of Aerospace Studies, and the University of British Columbia, with the assistance of the University of Vienna. [less ▲]Detailed reference viewed: 24 (1 ULg) A Coordinated X-Ray and Optical Campaign of the Nearest Massive Eclipsing Binary, δ Orionis Aa. IV. A Multiwavelength, Non-LTE Spectroscopic AnalysisShenar, T.; Oskinova, L.; Hamann, W.-R. et alin Astrophysical Journal (2015), 809Eclipsing systems of massive stars allow one to explore the properties of their components in great detail. We perform a multi-wavelength, non-LTE analysis of the three components of the massive multiple ... [more ▼]Eclipsing systems of massive stars allow one to explore the properties of their components in great detail. We perform a multi-wavelength, non-LTE analysis of the three components of the massive multiple system δ Ori A, focusing on the fundamental stellar properties, stellar winds, and X-ray characteristics of the system. The primary’s distance-independent parameters turn out to be characteristic for its spectral type (O9.5 II), but usage of the Hipparcos parallax yields surprisingly low values for the mass, radius, and luminosity. Consistent values follow only if δ Ori lies at about twice the Hipparcos distance, in the vicinity of the σ-Orionis cluster. The primary and tertiary dominate the spectrum and leave the secondary only marginally detectable. We estimate the V-band magnitude difference between primary and secondary to be {{Δ }}V≈ 2\buildrel{{m}}\over{.} 8. The inferred parameters suggest that the secondary is an early B-type dwarf (≈B1 V), while the tertiary is an early B-type subgiant (≈B0 IV). We find evidence for rapid turbulent velocities (∼200 km s[SUP]‑1[/SUP]) and wind inhomogeneities, partially optically thick, in the primary’s wind. The bulk of the X-ray emission likely emerges from the primary’s stellar wind ({log}{L}[SUB]{{X[/SUB]}}/{L}[SUB]{Bol[/SUB]}≈ -6.85), initiating close to the stellar surface at {R}[SUB]0[/SUB]∼ 1.1 {R}[SUB]*[/SUB]. Accounting for clumping, the mass-loss rate of the primary is found to be {log}\dot{M}≈ -6.4 ({M}[SUB]ȯ [/SUB] {{yr}}[SUP]-1[/SUP]), which agrees with hydrodynamic predictions, and provides a consistent picture along the X-ray, UV, optical, and radio spectral domains. [less ▲]Detailed reference viewed: 14 (1 ULg)