Search results for "isolation"

Vibrational relaxation of matrix-isolated carboxylic acid dimers and monomers.

2009

Femtosecond mid-IR transient absorption spectroscopy was used to probe the vibrational dynamics of formic acid and acetic acid isolated in solid argon following excitation of the fundamental transition of the carbonyl stretching mode. Carboxylic acids form extremely stable H-bonded dimers, hindering the study of the monomeric species at equilibrium conditions. The low-temperature rare-gas matrix isolation technique allows for a unique control over aggregation enabling the study of the monomer vibrational dynamics, as well as the dynamics of two distinct dimer structures (cyclic and open chain). This study provides insight into the role of the methyl rotor and hydrogen bonding in the vibrati…

Isolation and identification of roseotoxin S from cultures of the fungus Trichothecium roseum

1988

The structure of reseotoxin S, a new cyclodepsipeptide of the fungus Trichothecium roseum, is described. It consists of three amino acids and two hydroxy acids. Besides the structure, possibilities of proof and isolation as well as analytical data are given.

Isolation, separation and quantification of metabolites of the carcinogenic polycyclic aromatic hydrocarbon dibenz(a,h)anthracene

1986

An Accurate Quartic Force Field and Fundamental Frequencies for the Ozonide Anion: A Rare Positive Anharmonicity for the Antisymmetric Stretch

2003

The CCSD(T) method has been used to compute a highly accurate quartic force field and fundamental frequencies for all 16O and 18O isotopomers of the ozonide anion. The CCSD and CASPT2 methods have also been used to verify the reliability of the CCSD(T) fundamental frequencies. The computed fundamental frequencies are in agreement with gas-phase experiments, but disagree with matrix isolation experiments for the antisymmetric stretch, ν3. CASPT2 calculations show that the antisymmetric part of the O3- potential surface is sensitive to the external environment. It is concluded that the antisymmetric stretch exhibits a significant matrix shift in the matrix isolation experiments and that the m…

Individual Differences in Self-Talk Frequency: Social Isolation and Cognitive Disruption

2019

Despite the popularity of research on intrapersonal communication across many disciplines, there has been little attention devoted to the factors that might account for individual differences in talking to oneself. In this paper, I explore two possible explanations for who people might differ in the frequency of their self-talk. According to the “social isolation” hypothesis, spending more time alone or having socially-isolating experiences will be associated with increased self-talk. According to the “cognitive disruption” hypothesis, having self-related experiences that are cognitively disruptive will be associated with increased self-talk frequency. Several studies using the Self-Talk Sc…

Origin and evolution of Artemia reproductive and genetic diversity

2017

El modo de reproducción de una especie determina su diversidad genética y, a su vez, su éxito ecológico y evolutivo (Normarck et al., 2003; Simon et al., 2003; De Meeûs et al, 2007). En una población sexual, la recombinación meiótica permite que nuevas combinaciones de genes se formen y destruyan constantemente. De hecho, las poblaciones sexuales son generalmente más diversas genéticamente en comparación con las poblaciones asexuales. Por el contrario, en un linaje estrictamente asexual, donde se supone que la mutación (con la mayoría de mutantes deletéreos) sea la única fuente de diversidad genética, se espera que la diversidad clonal de la población se reduzca en cada generación. Por esto…

Robust fault detection for switched systems with time-varying delay using delta operator approach

2014

Bioactive alkaloids of hallucinogenic mushrooms

2015

The aim of our chapter is to review recent developments in a group of medicinally important natural products–alkaloids, with reference to the structure–activity studies in respect of certain diseases. Alkaloids covered by our review come from mushrooms called “hallucinogenic.” Hallucinogenic compounds have been chemically identified in mushrooms belonging to various genera, e.g., Agrocybe, Amanita, Conocybe, Galerina, Gymnopilus, Hypholoma, Inocybe, Panaeolus, Psilocybe, Pholiotina, Pluteus, and Weraroa [J.W. Allen, Ethnomycol. J. Sacred Mushroom Stud. 9 (2012) 130–175]. One of the largest classes of alkaloids is indole alkaloids. Indoles are probably the most widely distributed heterocycli…

A study of the atmospherically important reactions of dimethylsulfide (DMS) with I2 and ICl using infrared matrix isolation spectroscopy and electron…

2012

The reactions of dimethylsulfide (DMS) with molecular iodine (I(2)) and iodine monochloride (ICl) have been studied by infrared matrix isolation spectroscopy by co-condensation of the reagents in an inert gas matrix. Molecular adducts of DMS + I(2) and DMS + ICl have also been prepared using standard synthetic methods. The vapour above each of these adducts trapped in an inert gas matrix gave the same infrared spectrum as that recorded for the corresponding co-condensation reaction. In each case, the infrared spectrum has been interpreted in terms of a van der Waals adduct, DMS : I(2) and DMS : ICl, with the aid of infrared spectra computed for their minimum energy structures at the MP2 lev…

Quantitative Rotor Broken Bar Evaluation in Double Squirrel Cage Induction Machines under Dynamic Operating Conditions

2013

Advanced monitoring techniques leading to fault diagnosis and prediction of induction machine faults, operating under non-stationary conditions have gained strength because of its considerable influence on the operational continuation of many industrial processes. In case of rotor broken bars, fault detection based on sideband components issued from currents, flux, instantaneous control or power signals under different load conditions, may fail due to the presence of inter-bar currents that reduce the degree of rotor asymmetry, especially for double squirrel cage induction motors. But the produced core vibrations in the axial direction, can be investigated to overcome the limitation of the …