Acrolein Dimer as a Marker for Direct Detection of Acrolein in Wine

Acrolein is highly toxic and its presence in wine has been correlated with the development of bitterness.Analytical detection and quantification in aqueous solutions are challenging due to high reactivityand problems with chemical derivative analysis. Here we demonstrate the potential of a naturalderivative, formed under conditions prevailing in wine, as a marker for acrolein detection. Solid-phasemicroextraction (SPME) coupled with gas chromatograph mass spectrometry (GC-MS) was validated asa technique for direct detection of the acrolein dimer. Conventional GC-MS analysis using a quadrupolemass spectrometer did not provide sufficient chromatographic resolution for the separation of the targetanalyte from interfering compounds. Accurate mass measurements with time-of-flight (TOF)-MS, on theother hand, allowed qualitative and quantitative measurements of the acrolein dimer. This work lays theanalytical foundation for studies on the evolution of acrolein and its dimer in solution

Monte-Carlo sampling of energy-constrained quantum superpositions in high-dimensional Hilbert spaces

Recent studies into the properties of quantum statistical ensembles in high-dimensional Hilbert spaces have encountered difficulties associated with the Monte-Carlo sampling of quantum superpositions constrained by the energy expectation value. A straightforward Monte-Carlo routine would enclose the energy constrained manifold within a larger manifold, which is easy to sample, for example, a hypercube. The efficiency of such a sampling routine decreases exponentially with the increase of the dimension of the Hilbert space, because the volume of the enclosing manifold becomes exponentially larger than the volume of the manifold of interest. The present paper explores the ways to optimise the above routine by varying the shapes of the manifolds enclosing the energy-constrained manifold. The resulting improvement in the sampling efficiency is about a factor of five for a 14-dimensional Hilbert space. The advantage of the above algorithm is that it does not compromise on the rigorous statistical nature of the sampling outcome and hence can be used to test other more sophisticated Monte-Carlo routines. The present attempts to optimise the enclosing manifolds also bring insights into the geometrical properties of the energy constrained manifold itself.Comment: 9 pages, 7 figures, accepted for publication in European Physical Journal

The SARAO MeerKAT 1.3 GHz Galactic Plane Survey

We present the SARAO MeerKAT Galactic Plane Survey (SMGPS), a 1.3 GHz continuum survey of almost half of the Galactic Plane (251○ ≤l ≤ 358○ and 2○ ≤l ≤ 61○ at |b| ≤ 1 5). SMGPS is the largest, most sensitive and highest angular resolution 1 GHz survey of the Plane yet carried out, with an angular resolution of 8″ and a broadband RMS sensitivity of ∼10–20 μJy beam−1. Here we describe the first publicly available data release from SMGPS which comprises data cubes of frequency-resolved images over 908–1656 MHz, power law fits to the images, and broadband zeroth moment integrated intensity images. A thorough assessment of the data quality and guidance for future usage of the data products are given. Finally, we discuss the tremendous potential of SMGPS by showcasing highlights of the Galactic and extragalactic science that it permits. These highlights include the discovery of a new population of non-thermal radio filaments; identification of new candidate supernova remnants, pulsar wind nebulae and planetary nebulae; improved radio/mid-IR classification of rare Luminous Blue Variables and discovery of associated extended radio nebulae; new radio stars identified by Bayesian cross-matching techniques; the realisation that many of the largest radio-quiet WISE H II region candidates are not true H II regions; and a large sample of previously undiscovered background H I galaxies in the Zone of Avoidance

All-glass system for preparative glass capillary gas chromatography

An all-glass effluent splitter of virtually zero dead-volume and a peak collecting device were developed for the recovery of pure samples from the effluent of glass capillary columns for field testing, organoleptic evaluation or spectral identification. © 1983.Articl

Headspace gas analysis liquid desorption of headspace volatiles trapped on activated carbon open tubular traps

The liquid desorption of headspace volatiles from Grob-Habich activated carbon open tubular traps with small volumes of solvent and capillary column gas chromatographic analysis of the resulting solutions in an on-column type of procedure, was found to be an excellent alternative to thermal desorption which, in the case of thermally labile compounds, may lead to the formation of artefacts. The influence of the solvent volume and its flow-rate through the traps on the efficiency with which the adsorbed material is desorbed and transported to the capillary column, were investigated. It was found that practically quantitative recovery of trapped terpenes could be achieved with 5 μl of methylene chloride at a flow-rate of 0.5 μl/s. The efficiency of liquid desorption and the simplicity of the on-column liquid desorption technique was illustrated in a headspace gas determination of an imitation fruit drink. © 1987.Articl

Characterization of dog repellent factor from cuticular secretion of female yellow dog tick, Haemaphysalis leachi

During its natural life cycle, the yellow dog tick, Haemaphysalis leachi, has three hosts, and it has to spend enough time on each of them to complete a blood meal. When irritated, the females of this tick species produce a cuticular secretion that contains a dog-repelling allomone. This improves the tick's chances of survival by deterring the dog from biting the tick off its body. Employing response-guided isolation techniques in conjunction with gas chromatography-mass spectrometry, the defensive allomone of H. leachi was found to consist of the six homologous aliphatic aldehydes from hexanal to undecanal. A mixture of synthetic versions of these six aldehydes in quantities corresponding to those secreted by one tick elicited strong aversion reactions in the majority of dogs of various breeds. © 2006 Springer Science + Business Media, Inc.Articl

The chemical nature of the defensive larval secretion of the moth, Catochria catocaloides

The defensive larval secretion of Catochria catocaloides was determined by nuclear magnetic resonance and mass spectrometry as a solution of up to 38% formic acid in water. © 1976.Articl

Chemical constituents of the chest gland secretion of the thick-tailed galago (Galago crassicaudatus)

The naturally exuded chest gland secretions of adult male and female thick-tailed bush babies were collected directly in capillary tubes. The pure secretion was subjected to GC-MS analysis which revealed three major components. These were identified by comparison with the appropriate standard compounds: benzyl cyanide, p-hydroxybenzyl cyanide, and 2-(p-hydroxyphenyl)ethanol. Analysis of a male and a female secretion indicated that some sexual dimorphism in the relative concentrations of these components may exist. © 1979 Plenum Publishing Corporation.Articl