A Langmuir multi-probe system for the characterization of atmospheric pressure arc plasmas

The 'high-pressure' atmospheric (TIG) arc plasma is studied by means of a multi-Langmuir probe system. In order to determine the appropriate regime of operation, definitions of the plasma parameters for the description of the argon arc are considered and evaluations are presented. A description of the probe basic techniques is followed by an in-depth discussion of the different regimes of probe operation. The emphasis is put on atmospheric and flowing (arc) regimes. Probe sheath theories are compared and “Nonidealities” like cooling due to plasma-probe motion and probe emission mechanisms are then described. The extensive literature review reveals that the existing probe theories are inappropriate for a use in the TIG arc, because of ‘high’ pressure (atmospheric), broad range of ionization across the arc, flowing conditions, and ultimately, to the uncertainty about onset of Local Thermodynamical Equilibrium. The Langmuir probe system is built to operate in floating and biased conditions. The present work represents the first extensive investigation of electrostatic probes in arcs where the experimental difficulties and the primary observed quantities are presented in great detail. Analysis methodologies are introduced and experimental results are presented towards a unified picture of the resulting arc structure by comparison with data from emission spectroscopy. Results from different measurements are presented and comparison is made with data on TIG arcs present in literature. Probe obtained temperatures are lower than the values obtained from emission spectroscopy and this ‘cooling’ is attributed to electron-ion recombination. However, it is believed that probes can access temperatures regions not attainable by emission spectroscopy. Only axial electric potential and electric field are obtained because of the equipotential-probe requirement. Estimations of the sheath voltage and extension are obtained and a qualitative picture of the ion and electron current densities within the arc is given.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Free and Enzymatically Hydrolysed Volatile Compounds of Sweet Wines from Malvasia and Muscat Grapes (Vitis vinifera L.) Grown in Sardinia

The aroma of Muscat of Sorso-Sennori and Malvasia di Bosa wines obtained from grapes grown in Sardinia wasevaluated by instrumental analysis. Gas chromatography/mass spectrometry was used to identify and quantifythe content of free and bound volatile compounds. The odour activity value (OAV) was also calculated. Higheralcohols and esters were quantitatively the largest group of free volatile compounds in both wines, while terpeneswere the main class of bound volatiles. A total of 52 free and 26 bound volatiles were detected. Malvasia di Bosasweet wine had a higher content of alcohols, esters and acids in comparison to Muscat of Sorso-Sennori, whichwas richer in some terpenes, like nerol, geraniol and geranic acid, and also in bound volatile compounds. Atotal of 12 compounds were above the OAV. The main aroma-active compounds of Muscat were 3-methylbutylacetate (banana), ethyl octanoate and hexanoate (fruity), and linalool (flowery), Malvasia wine was characterisedparticularly by ethyl octanoate and by 3-methylbutyl acetate

Effect of Bottle Storage on Colour, Phenolics and Volatile Composition of Malvasia and Moscato White Wines

The effect of bottle storage on the colour, phenolics and volatile composition of Malvasia and Muscat winesobtained from grapes grown in Sardinia was evaluated. Colour was evaluated by UV-VIS spectrophotometryand by tristimulus colorimetry. Polyphenols were analysed by UV-VIS spectrophotometry and HPLCDAD.GC/MS was used to identify and quantify the content of free and bound volatile compounds. Asexpected, the absorbance values at 420 nm increased significantly for both wines during storage, due tooxidative browning, while difference in colour (DE*) from the beginning of storage and after 18 monthswas more intense in the Muscat wine than in the Malvasia wine. A significant decrease was observed indifferent phenolic compounds over time, especially in the Malvasia wine. In-bottle storage for 18 monthsat 20°C in the dark resulted in a significant decrease in all the classes of free and bound volatiles. Thesefinding enhance knowledge regarding the effects of bottle storage on Muscat and Malvasia wines. Thisis of interest because, rather surprisingly, this topic has been poorly investigated in relation to these twovarieties

Occurrence and transformation of illicit drugs in wastewater treatment plants.

Illicit drugs (IDs) and their metabolites have been recently recognized as a new group of water emerging contaminants (ECs) with potent psychoactive properties and unknown effects to the aquatic environment (Pal et al., 2013). IDs are excreted via urine and feces and arrive at wastewater treatment plants (WWTPs) where can reach ppb levels (Castiglioni et al., 2006). Over the past few years, it has been demonstrated that conventional biological processes in WWTPs are not or scarcely able to remove IDs. Thus, they are discharged into water bodies through the treated effluent (Postigo et al., 2011). Therefore, monitoring the IDs concentration in WWTPs can have a twofold advantage: i. increase knowledge on the amount of IDs discharged in the environment and estimate their effect; ii. estimating indirectly the community level consumption (Senta et al., 2014). The objective of this paper is to provide a comprehensive analysis of the occurrence and behaviour of illicit drugs and their metabolites in two Sicilian WWTPs. Specifically, two WWTPs (namely, WWTP-1 and WWTP-2) located at the north-western Sicilian coast have been monitored for 5 months (one sampling per week). The two WWTPs have a conventional scheme and mainly differ for their potentiality. Indeed, the average daily flow expressed as m3d-1 for WWTP-1 and WWTP-2 was equal to 153,600 and 19,704, respectively. Samples were analyzed for total suspended solids (TSS), illicit drugs and their metabolites (metham-phetamine; COC = cocaine; MDMA = 3,4-methylenedioxymethamphetamine; METH = methadone; EDDP = 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine; MDA = 3,4-methylenedioxy amphetamine; MDEA = 3,4-methylenedioxy ethylamphetamine; THC-COOH = 11-nor-9-carboxy-\u3949-tetrahydrocannabinol; BEG= Benzoylecgonine). In order to provide a fast and sensitive approach to quantify IDs, an automated online sample preparation method has been developed. The method uses a Thermo Scientific Transcend TLX-1 system powered by TurboFlowTM technology coupled with a TSQ Quantiva Triple Quadrupole Mass Spectrometer. Specifically, THC-COOH has been extracted from 75 \ub5L of pre-filtered water (using 7 and 0.4 \ub5m paper filters) by an online sample extraction method and quantified using an isotopic dilution approach between 30 and 2000 ng L-1

Nucleocytoplasmic transport: a thermodynamic mechanism

The nuclear pore supports molecular communication between cytoplasm and nucleus in eukaryotic cells. Selective transport of proteins is mediated by soluble receptors, whose regulation by the small GTPase Ran leads to cargo accumulation in, or depletion from the nucleus, i.e., nuclear import or nuclear export. We consider the operation of this transport system by a combined analytical and experimental approach. Provocative predictions of a simple model were tested using cell-free nuclei reconstituted in Xenopus egg extract, a system well suited to quantitative studies. We found that accumulation capacity is limited, so that introduction of one import cargo leads to egress of another. Clearly, the pore per se does not determine transport directionality. Moreover, different cargo reach a similar ratio of nuclear to cytoplasmic concentration in steady-state. The model shows that this ratio should in fact be independent of the receptor-cargo affinity, though kinetics may be strongly influenced. Numerical conservation of the system components highlights a conflict between the observations and the popular concept of transport cycles. We suggest that chemical partitioning provides a framework to understand the capacity to generate concentration gradients by equilibration of the receptor-cargo intermediary.Comment: in press at HFSP Journal, vol 3 16 text pages, 1 table, 4 figures, plus Supplementary Material include

Brain computer tomography in critically ill patients -- a prospective cohort study

<p>Abstract</p> <p>Background</p> <p>Brain computer tomography (brain CT) is an important imaging tool in patients with intracranial disorders. In ICU patients, a brain CT implies an intrahospital transport which has inherent risks. The proceeds and consequences of a brain CT in a critically ill patient should outweigh these risks. The aim of this study was to critically evaluate the diagnostic and therapeutic yield of brain CT in ICU patients.</p> <p>Methods</p> <p>In a prospective observational study data were collected during one year on the reasons to request a brain CT, expected abnormalities, abnormalities found by the radiologist and consequences for treatment. An “expected abnormality” was any finding that had been predicted by the physician requesting the brain CT. A brain CT was “diagnostically positive”, if the abnormality found was new or if an already known abnormality was increased. It was “diagnostically negative” if an already known abnormality was unchanged or if an expected abnormality was not found. The treatment consequences of the brain CT, were registered as “treatment as planned”, “treatment changed, not as planned”, “treatment unchanged”.</p> <p>Results</p> <p>Data of 225 brain CT in 175 patients were analyzed. In 115 (51%) brain CT the abnormalities found were new or increased known abnormalities. 115 (51%) brain CT were found to be diagnostically positive. In the medical group 29 (39%) of brain CT were positive, in the surgical group 86 (57%), <it>p</it> 0.01. After a positive brain CT, in which the expected abnormalities were found, treatment was changed as planned in 33%, and in 19% treatment was changed otherwise than planned.</p> <p>Conclusions</p> <p>The results of this study show that the diagnostic and therapeutic yield of brain CT in critically ill patients is moderate. The development of guidelines regarding the decision rules for performing a brain CT in ICU patients is needed.</p

Identifying candidate genes affecting developmental time in Drosophila melanogaster: pervasive pleiotropy and gene-by-environment interaction

<p>Abstract</p> <p>Background</p> <p>Understanding the genetic architecture of ecologically relevant adaptive traits requires the contribution of developmental and evolutionary biology. The time to reach the age of reproduction is a complex life history trait commonly known as developmental time. In particular, in holometabolous insects that occupy ephemeral habitats, like fruit flies, the impact of developmental time on fitness is further exaggerated. The present work is one of the first systematic studies of the genetic basis of developmental time, in which we also evaluate the impact of environmental variation on the expression of the trait.</p> <p>Results</p> <p>We analyzed 179 co-isogenic single <it>P[GT1]-</it>element insertion lines of <it>Drosophila melanogaster </it>to identify novel genes affecting developmental time in flies reared at 25°C. Sixty percent of the lines showed a heterochronic phenotype, suggesting that a large number of genes affect this trait. Mutant lines for the genes <it>Merlin </it>and <it>Karl </it>showed the most extreme phenotypes exhibiting a developmental time reduction and increase, respectively, of over 2 days and 4 days relative to the control (a co-isogenic <it>P</it>-element insertion free line). In addition, a subset of 42 lines selected at random from the initial set of 179 lines was screened at 17°C. Interestingly, the gene-by-environment interaction accounted for 52% of total phenotypic variance. Plastic reaction norms were found for a large number of developmental time candidate genes.</p> <p>Conclusion</p> <p>We identified components of several integrated time-dependent pathways affecting egg-to-adult developmental time in <it>Drosophila</it>. At the same time, we also show that many heterochronic phenotypes may arise from changes in genes involved in several developmental mechanisms that do not explicitly control the timing of specific events. We also demonstrate that many developmental time genes have pleiotropic effects on several adult traits and that the action of most of them is sensitive to temperature during development. Taken together, our results stress the need to take into account the effect of environmental variation and the dynamics of gene interactions on the genetic architecture of this complex life-history trait.</p

Actin binding to WH2 domains regulates nuclear import of the multifunctional actin regulator JMY

© The Author(s), 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Molecular Biology of the Cell 23 (2012): 853-863, doi:10.1091/mbc.E11-12-0992.Junction-mediating and regulatory protein (JMY) is a regulator of both transcription and actin filament assembly. In response to DNA damage, JMY accumulates in the nucleus and promotes p53-dependent apoptosis. JMY's actin-regulatory activity relies on a cluster of three actin-binding Wiskott–Aldrich syndrome protein homology 2 (WH2) domains that nucleate filaments directly and also promote nucleation activity of the Arp2/3 complex. In addition to these activities, we find that the WH2 cluster overlaps an atypical, bipartite nuclear localization sequence (NLS) and controls JMY's subcellular localization. Actin monomers bound to the WH2 domains block binding of importins to the NLS and prevent nuclear import of JMY. Mutations that impair actin binding, or cellular perturbations that induce actin filament assembly and decrease the concentration of monomeric actin in the cytoplasm, cause JMY to accumulate in the nucleus. DNA damage induces both cytoplasmic actin polymerization and nuclear import of JMY, and we find that damage-induced nuclear localization of JMY requires both the WH2/NLS region and importin β. On the basis of our results, we propose that actin assembly regulates nuclear import of JMY in response to DNA damage.This work was supported by grants from the National Institutes of Health, an American Heart Association Predoctoral Fellowship (J.B.Z.), the Robert Day Allen Fellowship Fund (J.B.Z.), and a National Science Foundation Predoctoral Fellowship (B.B.)