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https://www.readbyqxmd.com/read/28738652/volatile-composition-of-merlot-red-wine-and-its-contribution-to-the-aroma-optimization-and-validation-of-analytical-method
#1
Stefany Grützmann Arcari, Vinicius Caliari, Marla Sganzerla, Helena Teixeira Godoy
A methodology for the determination of volatile compounds in red wine using headspace solid phase microextraction (HS-SPME) combined with gas chromatography-ion trap/ mass spectrometry (GC-IT/MS) and flame ionization detector (GC -FID) was developed, validated and applied to a sample of Brazilian red wine. The optimization strategy was conducted using the Plackett-Burman design for variable selection and central composite rotational design (CCRD). The response surface methodology showed that the performance of the extraction of the volatile compounds using divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber is improved with no sample dilution, the addition of 30% NaCl, applying an extraction temperature of 56°C and extraction time of 55min...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738554/amperometric-detector-for-gas-chromatography-based-on-a-silica-sol-gel-solid-electrolyte
#2
William H Steinecker, Krzysztof Miecznikowski, Pawel J Kulesza, Zechariah D Sandlin, James A Cox
An electrochemical cell comprising a silica sol-gel solid electrolyte, a working electrode that protrudes into a gas phase, and reference and counter electrodes that contact the solid electrolyte comprises an amperometric detector for gas chromatography. Under potentiostatic conditions, a current related to the concentration of an analyte in the gas phase is produced by its oxidation at the three-phase boundary among the sol-gel, working electrode, and the gas phase. The sol-gel is processed to contain an electrolyte that also serves as a humidistat to maintain a constant water activity even in the presence the gas chromatographic mobile phase...
November 1, 2017: Talanta
https://www.readbyqxmd.com/read/28738413/reliability-and-repeatability-of-cone-density-measurements-in-patients-with-stargardt-disease-and-rpgr-associated-retinopathy
#3
Preena Tanna, Melissa Kasilian, Rupert Strauss, James Tee, Angelos Kalitzeos, Sergey Tarima, Alexis Visotcky, Alfredo Dubra, Joseph Carroll, Michel Michaelides
Purpose: To assess reliability and repeatability of cone density measurements by using confocal and (nonconfocal) split-detector adaptive optics scanning light ophthalmoscopy (AOSLO) imaging. It will be determined whether cone density values are significantly different between modalities in Stargardt disease (STGD) and retinitis pigmentosa GTPase regulator (RPGR)-associated retinopathy. Methods: Twelve patients with STGD (aged 9-52 years) and eight with RPGR-associated retinopathy (aged 11-31 years) were imaged using both confocal and split-detector AOSLO simultaneously...
July 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28738252/radioactivity-analysis-of-soil-samples-taken-from-the-western-and-northern-shores-of-lake-van-turkey
#4
Halime Kayakökü, Mahmut Doğru
In this study, concentrations of the radioactive isotopes (226)Ra, (232)Th, (40)K and (137)Cs were measured in soil samples from the shores of Lake Van using a high purity germanium detector. Activity concentrations obtained for these nuclides were compared with world average values. The average (226)Ra, (232)Th and (4)(0)K activity concentrations calculated for the soil samples were higher than the world average values reported by UNSCEAR. The lowest (226)Ra, (232)Th and (4)(0)K activity concentrations were recorded in sample T-1 whereas the highest values were recorded in sample T-11...
July 12, 2017: Applied Radiation and Isotopes
https://www.readbyqxmd.com/read/28738077/consequences-of-severe-habitat-fragmentation-on-density-genetics-and-spatial-capture-recapture-analysis-of-a-small-bear-population
#5
Sean M Murphy, Ben C Augustine, Wade A Ulrey, Joseph M Guthrie, Brian K Scheick, J Walter McCown, John J Cox
Loss and fragmentation of natural habitats caused by human land uses have subdivided several formerly contiguous large carnivore populations into multiple small and often isolated subpopulations, which can reduce genetic variation and lead to precipitous population declines. Substantial habitat loss and fragmentation from urban development and agriculture expansion relegated the Highlands-Glades subpopulation (HGS) of Florida, USA, black bears (Ursus americanus floridanus) to prolonged isolation; increasing human land development is projected to cause ≥ 50% loss of remaining natural habitats occupied by the HGS in coming decades...
2017: PloS One
https://www.readbyqxmd.com/read/28737927/a-facile-non-reactive-hydrogen-peroxide-h2o2-detection-method-enabled-by-ion-chromatography-with-uv-detector
#6
Mingrui Song, Junli Wang, Baiyang Chen, Lei Wang
Hydrogen peroxide (H2O2) is present ubiquitously in natural environment and nowadays widely used in water and wastewater treatment processes for pollutant control. However, current analytical methods for H2O2 inevitably require reactions between H2O2 and other reactants to yield signals, thus likely subjective to interferences of coexisting colored, oxidative, and reductive compounds. In order to overcome these barriers, we herein for the first time propose to analyze H2O2 by ion chromatography (IC) equipped with ultraviolet (UV) detector...
July 24, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28737790/tuning-the-gap-of-lead-based-halide-perovskites-by-introducing-superalkali-species-at-the-cationic-sites-of-abx3-type-structure
#7
C Paduani, Andrew M Rappe
We study with scalar relativistic density functional theory (DFT) calculations the effect of changes in the ionicity of the bonding mechanism and charge donation on the structure and electronic properties of new lead halide perovskites which show promising performance in optoelectronic applications as long-wave infrared detectors and thermoelectrics. Our results provide evidence that the band gap of these compounds can be tuned upon the introduction of appropriate superalkali moieties at the cationic A-sites in the CsPbI3-type structure...
July 24, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28737161/linbo-sub-3-sub-surfaces-from-a-microscopic-perspective
#8
Simone Sanna, Wolf Gero Schmidt
A large number of oxides has been investigated in the last twenty years as possible new materials for various applications ranging from opto-electronics to heterogeneous catalysis. In this context, ferroelectric oxides are particularly promising. The electric polarization plays a crucial role at many oxide surfaces, and it largely determines their physical and chemical properties. Ferroelectrics offer in addition the possibility to control/switch the electric polarization and hence the surface chemistry, allowing for the realization of domain-engineered nanoscale devices such as molecular detectors or highly efficient catalysts...
July 24, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28737143/optimal-utilization-of-pediatric-computed-tomography-to-minimize-radiation-exposure-what-the-clinician-must-know-s
#9
Natasha Gupta, Lalendra Upreti
The number of computed tomography (CT) scans being done for children all over the world is on the rise ever since the advent of Multi-Detector CT (MDCT). However, CT is a potential source of harmful ionizing radiation, and children are more susceptible to its adverse effects. It is essential for the pediatrician as well as the radiologist to be aware of some important principles and guidelines, by following which, radiation exposure to the child can be minimized to the bare essential. It is important to have knowledge of the valid and justifiable indications of CT for the child, the correct technique of performing the scan, and the new technological innovations now available on modern scanners that help to minimize radiation dose...
July 15, 2017: Indian Pediatrics
https://www.readbyqxmd.com/read/28737014/clinical-implementation-of-an-exit-detector-based-dose-reconstruction-tool-for-helical-tomotherapy-delivery-quality-assurance
#10
Shrikant Deshpande, Aitang Xing, Peter Metcalfe, Lois Holloway, Philip Vial, Mark Geurts
PURPOSE: To validate the accuracy of an exit detector based dose reconstruction tool for Helical Tomotherapy (HT) delivery quality assurance (DQA). METHODS AND MATERIAL: Exit detector based DQA tool was developed for patient specific HT treatment verification. The tool performs a dose reconstruction on the planning image using the sinogram measured by the HT exit detector with no objects in the beam (i.e. static couch), and compares the reconstructed dose to the planned dose...
July 24, 2017: Medical Physics
https://www.readbyqxmd.com/read/28736472/a-radiative-transfer-equation-based-image-reconstruction-method-incorporating-boundary-conditions-for-diffuse-optical-imaging
#11
Abhinav K Jha, Yansong Zhu, Dean F Wong, Arman Rahmim
Developing reconstruction methods for diffuse optical imaging requires accurate modeling of photon propagation, including boundary conditions arising due to refractive index mismatch as photons propagate from the tissue to air. For this purpose, we developed an analytical Neumann-series radiative transport equation (RTE)-based approach. Each Neumann series term models different scattering, absorption, and boundary-reflection events. The reflection is modeled using the Fresnel equation. We use this approach to design a gradient-descent-based analytical reconstruction algorithm for a three-dimensional (3D) setup of a diffuse optical imaging (DOI) system...
February 11, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28736285/optimization-of-gate-simulations-for-whole-body-planar-scintigraphic-acquisitions-using-the-xcat-male-phantom-with-177-lu-dotatate-biokinetics-in-a-siemens-symbia-t2
#12
G C A Costa, D A B Bonifácio, D Sarrut, T Cajgfinger, M Bardiès
Simulations of planar whole body acquisitions in therapeutic procedures are often extensively time-consuming and therefore rarely used. However, optimising tools and variance reduction techniques can be employed to overcome this problem. In this paper, a variety of features available in GATE are explored and their capabilities to reduce simulation time are evaluated. For this purpose, the male XCAT phantom was used as a virtual patient with (177)Lu-DOTATATE pharmacokinetic for whole body planar acquisition simulations in a Siemens Symbia T2 model...
July 20, 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28735452/characterization-of-polymeric-substance-classes-in-cereal-based-beverages-using-asymmetrical-flow-field-flow-fractionation-with-a-multi-detection-system
#13
Georg Krebs, Thomas Becker, Martina Gastl
Cereal-based beverages contain a complex mixture of various polymeric macromolecules including polysaccharides, peptides, and polyphenols. The molar mass of polymers and their degradation products affect different technological and especially sensory parameters of beverages. Asymmetrical flow field-flow fractionation (AF4) coupled with multi-angle light scattering (MALS) and refractive index detection (dRI) or UV detection (UV) is a technique for structure and molar mass distribution analysis of macromolecules commonly used for pure compound solutions...
July 22, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28735451/importance-of-icpms-for-speciation-analysis-is-changing-future-trends-for-targeted-and-non-targeted-element-speciation-analysis
#14
Joerg Feldmann, Andrea Raab, Eva M Krupp
This article is aimed at researchers interested in organic molecules which contain a heteroatom but who have never considered using inductively coupled plasma mass spectrometry (ICPMS) or who have used ICPMS for years and developed numerous methods for analysis of target elemental species. We try to illustrate (1) that ICPMS has been very useful for speciation analysis of metal(loid) target species and that there is now a trend to replace the costly detector with cheaper detection systems for routine target analysis, and (2) that ICPMS has been used and will be used even more in the future for non-targeted analysis of elements which are not normally associated with ICPMS analysis, such as non-metals such as sulfur, phosphorus, chlorine and fluorine...
July 22, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28735405/profiling-abscisic-acid-induced-changes-in-fatty-acid-composition-in-mosses
#15
Suhas Shinde, Shivakumar Devaiah, Aruna Kilaru
In plants, change in lipid composition is a common response to various abiotic stresses. Lipid constituents of bryophytes are of particular interest as they differ from that of flowering plants. Unlike higher plants, mosses have high content of very long-chain polyunsaturated fatty acids. Such lipids are considered to be important for survival of nonvascular plants. Here, using abscisic acid (ABA )-induced changes in lipid composition in Physcomitrella patens as an example, a protocol for total lipid extraction and quantification by gas chromatography (GC) coupled with flame ionization detector (FID) is described...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/28734362/discrimination-of-bacteria-by-rapid-sensing-their-metabolic-volatiles-using-an-aspiration-type-ion-mobility-spectrometer-a-ims-and-gas-chromatography-mass-spectrometry-gc-ms
#16
Ileana Andreea Ratiu, Victor Bocos-Bintintan, Adrian Patrut, Victor Hugo Moll, Matthew Turner, C L Paul Thomas
The objective of our study was to investigate whether one may quickly and reliably discriminate different microorganism strains by direct monitoring of the headspace atmosphere above their cultures. Headspace samples above a series of in vitro bacterial cultures were directly interrogated using an aspiration type ion mobility spectrometer (a-IMS), which produced distinct profiles ("fingerprints") of ion currents generated simultaneously by the detectors present inside the ion mobility cell. Data processing and analysis using principal component analysis showed net differences in the responses produced by volatiles emitted by various bacterial strains...
August 22, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28733001/degradation-of-endocrine-disruptor-bisphenol-a-by-ultrasound-assisted-electrochemical-oxidation-in-water
#17
Matz Dietrich, Marcus Franke, Michael Stelter, Patrick Braeutigam
Micropollutants are becoming an increasing problem for the environment and wastewater treatment. One example is Bisphenol A (BPA), an endocrinic disruptor, which is widely used in plastic production. Due to its endocrine disrupting effects on aquatic (micro-)organisms and its ubiquity, in surface- and wastewater alike, adequate treatment techniques are necessary. In this study, the degradation of BPA by a sonoelectrochemical hybrid system was investigated, using a low frequency (24kHz) ultrasound horn and two boron doped diamond electrodes...
November 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28732010/biofilm-imaging-in-porous-media-by-laboratory-x-ray-tomography-combining-a-non-destructive-contrast-agent-with-propagation-based-phase-contrast-imaging-tools
#18
Maxence Carrel, Mario A Beltran, Verónica L Morales, Nicolas Derlon, Eberhard Morgenroth, Rolf Kaufmann, Markus Holzner
X-ray tomography is a powerful tool giving access to the morphology of biofilms, in 3D porous media, at the mesoscale. Due to the high water content of biofilms, the attenuation coefficient of biofilms and water are very close, hindering the distinction between biofilms and water without the use of contrast agents. Until now, the use of contrast agents such as barium sulfate, silver-coated micro-particles or 1-chloronaphtalene added to the liquid phase allowed imaging the biofilm 3D morphology. However, these contrast agents are not passive and potentially interact with the biofilm when injected into the sample...
2017: PloS One
https://www.readbyqxmd.com/read/28731818/the-adron-rm-instrument-onboard-the-exomars-rover
#19
I G Mitrofanov, M L Litvak, S Y Nikiforov, I Jun, Y I Bobrovnitsky, D V Golovin, A S Grebennikov, F S Fedosov, A S Kozyrev, D I Lisov, A V Malakhov, M I Mokrousov, A B Sanin, V N Shvetsov, G N Timoshenko, T M Tomilina, V I Tret'yakov, A A Vostrukhin
This overview presents the physical principles, design, measurement capabilities, and summary of planned operations of the autonomous detector of radiation of neutrons onboard rover at Mars (ADRON-RM) on the surface of Mars. ADRON-RM is a Russian project selected for the joint European Space Agency-Roscosmos ExoMars 2020 landing mission. A compact passive neutron spectrometer, ADRON-RM, was designed to study the abundance and distribution of water and neutron absorption elements (such as Cl, Fe, and others) in the martian subsurface along the path of the ExoMars rover...
June 2017: Astrobiology
https://www.readbyqxmd.com/read/28731817/infrared-spectrometer-for-exomars-a-mast-mounted-instrument-for-the-rover
#20
Oleg I Korablev, Yurii Dobrolensky, Nadezhda Evdokimova, Anna A Fedorova, Ruslan O Kuzmin, Sergei N Mantsevich, Edward A Cloutis, John Carter, Francois Poulet, Jessica Flahaut, Andrew Griffiths, Matthew Gunn, Nicole Schmitz, Javier Martín-Torres, Maria-Paz Zorzano, Daniil S Rodionov, Jorge L Vago, Alexander V Stepanov, Andrei Yu Titov, Nikita A Vyazovetsky, Alexander Yu Trokhimovskiy, Alexander G Sapgir, Yurii K Kalinnikov, Yurii S Ivanov, Alexei A Shapkin, Andrei Yu Ivanov
ISEM (Infrared Spectrometer for ExoMars) is a pencil-beam infrared spectrometer that will measure reflected solar radiation in the near infrared range for context assessment of the surface mineralogy in the vicinity of the ExoMars rover. The instrument will be accommodated on the mast of the rover and will be operated together with the panoramic camera (PanCam), high-resolution camera (HRC). ISEM will study the mineralogical and petrographic composition of the martian surface in the vicinity of the rover, and in combination with the other remote sensing instruments, it will aid in the selection of potential targets for close-up investigations and drilling sites...
June 2017: Astrobiology
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