Search results for " infrared"
showing 10 items of 945 documents
Fully cosmological virtual massive galaxies at z=0: kinematical, morphological, and stellar population characterisation
2013
We present the results of a numerical adaptive mesh refinement hydrodynamical and N-body simulation in a $\Lambda CDM$ cosmology. We focus on the analysis of the main properties of massive galaxies ($M_* > 10^{11}\,M_{\odot}$) at $z=0$. For all the massive virtual galaxies we carry out a careful study of their one dimensional density, luminosity, velocity dispersion, and stellar population profiles. In order to best compare with observational data, the method to estimate the velocity dispersion is calibrated by using an approach similar to that performed in the observations, based on the stellar populations of the simulated galaxies. With these ingredients, we discuss the different properti…
The intriguing properties of local compact massive galaxies: What are they?
2012
AbstractStudying the properties of the few compact massive galaxies that exist in the local Universe (Trujillo et al. 2009) might provide a closer look to the nature of their high redshift (z ≥ 1.0) massive counterparts. By this means we have characterized their main kinematics, structural properties, stellar populations and star formation histories with a set of new high quality spectroscopic and imaging data (Ferré-Mateu et al. 2012 and Trujillo et al. 2012). These galaxies seem to be truly unique, as they do not follow the characteristic kinematics, stellar surface mass density profiles and stellar population patterns of present-day massive ellipticals or spirals of similar mass. They ar…
Mechanisms underlying the toxicity of lactone aroma compounds towards the producing yeast cells
2003
M. A G U E D O , L. B E N E Y , Y. W A C H EA N D J. - M. B E L I N. 2003. Aims: To study the fundamental mechanisms of toxicity of the fruity aroma compound c-decalactone, that lead to alterations in cell viability during its biotechnological production by yeast cells; Yarrowia lipolytica that is able to produce high amounts of this metabolite was used here as a model. Methods and Results: Lactone concentrations above 150 mg l )1 inhibited cell growth, depolarized the living cells and increased membrane fluidity. Infrared spectroscopic measurements revealed that the introduction of the lactone into model phospholipid bilayers, decreased the phase transition temperature. Moreover, the H + -…
A modular "toolbox" approach to flexible branched multimacrocyclic hosts as precursors for multiply interlocked architectures.
2008
Tetralactam macrocycles can be functionalized by a variety of cross-coupling reactions. A modular “toolbox” strategy is presented that allows 1) several tetralactam macrocycles to be covalently connected with each other or with a central spacer, 2) the macrocycles to be substituted with or connected to different chromophores, and 3) metal-coordination sites to be attached to the macrocycles. With this approach a series of different oligo-macrocyclic hosts was obtained with great structural diversity and enormous potential for further functionalization. Rotaxanes made on the basis of these macrocycles have been synthesized to demonstrate their utility in building more complex supramolecular …
Synthesis of Lamellarin U and Lamellarin G Trimethyl Ether by Alkylation of a Deprotonated α-Aminonitrile
2008
1,2,3,4-Tetrahydroisoquinoline-1-carbonitriles can serve as starting materials for the one-pot synthesis of 5,6-dihydropyrrolo[2,1 a]isoquinolines and 1-benzyl-3,4-dihydroisoquinolines. The latter compounds were transformed to lamellarin G trimethyl ether and lamellarin U in short reaction sequences. This method allows the introduction of acid-sensitive protecting groups for the phenolic hydroxy functions which would be cleaved under the harsh conditions of the classical Bischler-Napieralski reaction.
Dissolution behavior of co-amorphous amino acid-indomethacin mixtures: The ability of amino acids to stabilize the supersaturated state of indomethac…
2017
Article
Structural characterization and chemical classification of some bryophytes found in Latvia.
2013
Bryophytes are the second largest taxonomic group in the plant kingdom; yet, studies conducted to better understand their chemical composition are rare. The aim of this study was to characterize the chemical composition of bryophytes common in Northern Europe by using elemental, spectral, and non-destructive analytical methods, such as Fourier transform IR spectrometry (FT-IR), solid-phase (13) C-NMR spectrometry, and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), for the purpose of investigating their chemotaxonomic relationships on the basis of chemical-composition data. The results of all these analyses showed that bryophytes consist mainly of carbohydrates. Judging by FT-IR …
Unexpected identification and characterization of a cathinone precursor in the new psychoactive substance market: 3',4'-methylenedioxy-2,2-dibromobut…
2019
Abstract 3′,4′-methylenedioxy-2,2-dibromobutyrophenone has been identified and fully characterized in a sample obtained from an anonymous consumer acquired as ketamine through the Internet market. The substance has been deeply characterized by using standard and high performance analytical techniques such as: attenuated total reflectance-infrared spectroscopy, gas chromatography–mass spectrometry, high-resolution mass spectrometry, elemental analysis, and nuclear magnetic resonance, including 1H, 13C, distortionless enhancement by polarization transfer, two dimensional homonuclear 1H-1H correlation spectroscopy, and 1H-13C heteronuclear single-quantum correlation spectra. 3′,4′-methylenedio…
Circumdatin H, a new inhibitor of mitochondrial NADH oxidase, from Aspergillus ochraceus
2005
Circumdatin H (1), a new alkaloid from the culture broth of Aspergillus ochraceus, has been isolated, together with a known circumdatin, circumdatin E (2) and other known compounds: flavacol (3) and stephacidin A (4). The structure of 1 was established on the basis of chemical and spectral evidence. All of these alkaloids showed biological activity as inhibitors of the mammalian mitochondrial respiratory chain.
Acetylation of 5-Amino-1H-[1,2,4]triazole Revisited
2002
The products of the acetylation reactions of the common herbicide 5-amino-1H-[1,2,4]triazole were investigated using HPLC, GC-MS, 1H NMR, and FTIR spectroscopy. The conventional annular monoacetylation procedures with acetyl chloride are not regioselective and furnish a mixture of isomers. Traditional diacetylation in neat acetic anhydride under reflux produces a mixture of di-, mono-, and triacetylated derivatives. By using equivalent amounts of acetic anhydride in a dimethylformamide solution, a rapid and selective annular monoacetylation of 5-amino-1H-[1,2,4]triazole was achieved. The monoacetylation proceeds via the formation of the intermediate, 1-acetyl-3-amino-1H-[1,2,4]triazole, whi…