999 research outputs found
Locating Star-Forming Regions in Quasar Host Galaxies
We present a study of the morphology and intensity of star formation in the
host galaxies of eight Palomar-Green quasars using observations with the Hubble
Space Telescope. Our observations are motivated by recent evidence for a close
relationship between black hole growth and the stellar mass evolution in its
host galaxy. We use narrow-band [O II] 3727, H, [O III]
5007 and Pa images, taken with the WFPC2 and NICMOS
instruments, to map the morphology of line-emitting regions, and, after
extinction corrections, diagnose the excitation mechanism and infer
star-formation rates. Significant challenges in this type of work are the
separation of the quasar light from the stellar continuum and the
quasar-excited gas from the star-forming regions. To this end, we present a
novel technique for image decomposition and subtraction of quasar light. Our
primary result is the detection of extended line-emitting regions with sizes
ranging from 0.5 to 5 kpc and distributed symmetrically around the nucleus,
powered primarily by star formation. We determine star-formation rates of order
a few tens of M/yr. The host galaxies of our target quasars have
stellar masses of order M and specific star formation rates
on a par with those of M82 and luminous infrared galaxies. As such they fall at
the upper envelope or just above the star-formation mass sequence in the
specific star formation vs stellar mass diagram. We see a clear trend of
increasing star formation rate with quasar luminosity, reinforcing the link
between the growth of the stellar mass of the host and the black hole mass
found by other authors.Comment: Accepted for publication in M.N.R.A.
Searching for a Franco-German consensus on the future of Europe - survey results for Bundestag, Assemblée Nationale and Sénat
The Brexit referendum and the decision of British voters to leave the EU have sparked a comprehensive debate on the future of European integration. A key issue in this debate is the appropriate division of responsibilities between the EU and its Member States. The EU might still lack certain competencies which are crucial for a functioning Union or resilient euro area. At the same time, however, some of the EUâs existing competencies might be better allocated to Member States. This policy brief documents results from a survey on the future of European integration conducted in the national parliaments of both France and Germany, including the French SĂ©nat, the AssemblĂ©e Nationale and the German Bundestag, between April and July 2016
Intramolecular phosphine-promoted Knoevenagel based redox-reaction
A Knoevenagel based redox-reaction promoted by intramolecular phosphine sources is presented for the first time. The influence of different diketones, aldehydes, bases and acids was investigated. The effects of different substituents were evaluated based on their electronical influence on the diketone structure. With the obtained results a mechanism is proposed, giving information about transition states formed during the reaction, which can lead to different products. This type of an internal redox transformation with a phosphine oxide moiety remaining in the molecule after the redox reaction represents a new type of reaction
Evaluation of options and limits of aqueous all-quinone-based organic redox flow batteries
Redox flow batteries based on aqueous electrolytes with organic active material (ORFB) have great potential for the development of environmentally safe and ecologically sustainable energy storage systems. To be competitive with the state-of-the-art vanadium redox flow battery, organic electrolytes must meet a whole range of requirements. We investigated different anthraquinone-based electrolytes, i.e. anthraquinone-2,6-disulfonic acid, anthraquinone-2,7-disulfonic acid (2,7-AQDS), anthraquinone-2-sulfonic acid, and 1,2-dihydroxybenzene-3,5-disulfonic acid (BQDS) with respect to their solubility in sulfuric acid, their electrical conductivity, and their viscosity. For this purpose, the influence of the concentration of sulfuric acid and the active species on the electrolyte
properties was determined. Using NMR spectroscopy we analysed the thermal and electrochemical stability of 2,7-AQDS and BQDS electrolytes. The electrochemical stability was also monitored by cyclic voltammetry. Both methods have also indicated the
absence of crossover phenomena. Furthermore, the influence of the electrolyte properties on the performance of the ORFB was investigated. Comparison with the vanadium electrolyte allowed us to estimate these kinds of requirements in order to develop a comparable all-organic flow battery
Durable modification of wood by benzoylation: proof of covalent bonding by solution state NMR and DOSY NMR quick-test
A convenient, broadly applicable and durable wood protection was recently published by Kaufmann and Namyslo. This procedure efficiently allows for esterification of wood hydroxyl groups with (1H-benzotriazolyl)-activated functionalized benzoic acids. The result of such wood-modifying reactions is usually monitored by an increase in mass of the wood material (weight percent gain value, WPG) and by infrared spectroscopy (IR). However, diagnostic IR bands suffer from overlap with naturally occurring ester groups, mainly in the hemicellulose part of unmodified wood. In contrast to known NMR spectroscopy approaches that use the non-commonly available solid state techniques, herein we present solution state NMR proof of the covalent attachment of our organic precursors to wood. The finding is based on a time-efficient, non-uniformly sampled (NUS) solution state 1H,13C-HMBC experiment that only needs a tenth of the regular recording time. The appropriate NMR sample of thoroughly dissolved modified wood was prepared by a mild and non-destructive method. The 2D-HMBC shows a specific cross-signal caused by spinâspin coupling over three bonds from the ester carbonyl carbon atom to the α-protons of the esterified wood hydroxyl groups. This specific coupling pathway requires a covalent bonding as a conditio sine qua non. An even more rapid test to monitor the covalent bonding was achieved with an up-to-date diffusion-ordered spectroscopy sequence (OneshotâDOSY) based on 1H or 19F as the sensitive nucleus. The control experiment in a series of DOSY spectra gave a by far higher D value of (1.22 ± 0.06)·10â10 m2·sâ1, which is in accordance with fast diffusion of the âfreeâ and thus rapidly moving small precursor molecule provided as its methyl ester. In the case of a covalent attachment to wood, a significantly smaller D value of (0.12 ± 0.01)·10â10 m2·sâ1 was obtained
Simulation of haemodynamic flow in head and neck cancer chemotherapy
<p>Abstract</p> <p>Background</p> <p>In recent years, intra arterial chemotherapy has become an important component in head and neck cancer treatment. However, therapy success can vary significantly and consistent treatment guidelines are missing. The purpose of this study was to create a computer simulation of the chemical agent injection in the head and neck arteries to investigate the distribution and concentration of the chemical.</p> <p>Methods</p> <p>Realistic three dimensional patient specific geometry was created from image scan data. Pulsatile blood flow, turbulence, the chemical agent injection via a catheter, and the mixture between blood and the chemical were then simulated through the arterial network by computational fluid dynamics software.</p> <p>Results</p> <p>The results show a consistent chemical distribution throughout all the arteries and this is ineffective. In addition, due to high wall shear stress and turbulence at the inner bifurcation wall, serious complications during the treatment could occur, for instance haemolysis or thrombosis.</p> <p>Conclusions</p> <p>The modelled catheter position is insufficient to provide a high chemical agent concentration in the desired tumour feeding artery, which is vital for therapy success.</p
Novel nicotinoid structures for covalent modification of wood: an environmentally friendly way for its protection against insects
Timber is constantly exposed to environmental influences under outdoor conditions which limits its lifetime and usability. In order to counteract the damaging processes caused by insects, we have developed a novel and more environmentally friendly method to protect wood materials via covalent modification by organic insecticides. Starting with an important class of synthetic insecticides which are derived from the natural insecticide nicotine, various new carboxylic acid derivatives of imidacloprid were made accessible. These activated neonicotinoids were utilized for the chemical modification of wood hydroxy groups. In contrast to conventional wood preservation methods in which biocides are only physically bound to the surface for a limited time, the covalent fixation of the preservative guarantees a permanent effect against wood pests, demonstrated in standardized biological tests. Additionally, the environmental interaction caused by non-bound neonicotinoids is significantly reduced, since both, a smaller application rate is required and leaching of the active ingredient is prevented. By minimizing the pest infestation, the lifetime of the material increases while preserving the natural appearance of the material
Why Silver Deposition is so Fast: Solving the Enigma of Metal Deposition
A perfect match: Silver deposition is one of the fastest electrochemical reactions, even though the Ag+ ion loses more than 5â
eV solvation energy in the process. This phenomenon, an example of the enigma of metal deposition, was investigated by a combination of MD simulations, DFT, and specially developed theory. At the surface, the Ag+ ion experiences a strong interaction with the sp band of silver, which catalyzes the reaction.Fil: Pinto, Leandro M. C.. Universidade Estadual Paulista Julio de Mesquita Filho. Facultad de Filosofia E Ciencias-campus de Marilia; Brasil. Universitat Ulm; AlemaniaFil: Spohr, Eckhard. Universitat Duisburg - Essen; AlemaniaFil: Quaino, Paola Monica. Universidad Nacional del Litoral. Facultad de IngenierĂa QuĂmica. Programa de ElectroquĂmica Aplicada E IngenierĂa ElectroquĂmica; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Santa Fe; ArgentinaFil: Santos, Elizabeth del Carmen. Universitat Ulm; Alemania. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico CĂłrdoba. Instituto de FĂsica "Enrique Gaviola"; ArgentinaFil: Schmickler, Wolfgang. Institute Of Theoretical Chemistry; Alemania. Universitat Ulm; Alemani
Surface tuning of wood via covalent modification of its lignocellulosic biopolymers with substituted benzoates: a study on reactivity, efficiency, and durability
Chemical modification of wood applying benzo-
triazolyl-activated carboxylic acids has proven to be a versatile method for the durable functionalization of its lignocellulosic biopolymers. Through this process, the material properties of wood can be influenced and specifically optimized. To check the scope and limitations of this modification method, various benzamide derivatives with electron-withdrawing (EWG) or electron-donating (EDG) functional groups in different positions of the aromatic ring were synthesized and applied for covalent modification of Scots pine (Pinus sylvestris L.) sapwood in this study. The bonded amounts of substances (up to 2.20 mmol) were compared with the reactivity constants of the Hammett equation, revealing a significant correlation between the modification efficiency and the theoretical reactivity constants of the corresponding aromatic substitution pattern. The successful covalent attachment of the respective substituted benzamides was proven by attenuated total reflection infrared (ATR-IR) spectroscopy, while the stability of the newly formed ester bond was proven in a standardized leaching test
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