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Morten Beck Trelle, Shona H Pedersen, Eva Christina Østerlund, Jeppe Buur Madsen, Søren Risom Kristensen, Thomas J D Jørgensen
Antithrombin deficiency is associated with increased risk of venous thrombosis. In certain families this condition is caused by pathogenic polymerization of mutated antithrombin in the blood. To facilitate future development of pharmaceuticals against antithrombin polymerization an improved understanding of the polymerogenic intermediates is crucial. However, X-ray crystallography of these intermediates is severely hampered by the difficulty in obtaining well-diffracting crystals of transient and heterogeneous noncovalent protein assemblies...
October 26, 2016: Analytical Chemistry
Lumin Sun, Bingyan Lu, Dongxing Yuan, Wenbo Hao, Ying Zheng
Variations in the composition of stable isotopes of mercury contained in tissues (root, stem, leaf, and hypocotyl or flower) of three typical mangrove plants (Kandelia candel, Aegiceras corniculata, and Bruguiera gymnorhiza), collected from the mangrove wetland of Jiulong estuary, SE China, were used to investigate the sources and transformation of mercury in the mangrove plants. Tissue samples from the plants were digested and mercury in the solution was pre-concentrated with purge-trap method and then analyzed by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS)...
October 25, 2016: Environmental Science and Pollution Research International
Ondřej Zvěřina, Pavel Coufalík, Kristián Brat, Rostislav Červenka, Jan Kuta, Ondřej Mikeš, Josef Komárek
More than 400 seal mummies and skeletons are now mapped in the northern part of James Ross Island, Antarctica. Decomposing carcasses represent a rare source of both organic matter and associated elements for the soil. Owing to their high trophic position, seals are known to carry a significant mercury body burden. This work focuses on the extent of the mercury input from seal carcasses and shows that such carcasses represent locally significant sources of mercury and methylmercury for the environment. Mercury contents in soil samples from the surrounding areas were determined using a single-purpose AAS mercury analyzer...
October 25, 2016: Environmental Science and Pollution Research International
Paul Prior, Rachel Timmins, Julia Petryk, Jared Strydhorst, Yin Duan, Lihui Wei, R Glenn Wells
PURPOSE: In dual-isotope (Tc-99m/In-111) small-animal single-photon emission computed tomography (SPECT), quantitative accuracy of Tc-99m activity measurements is degraded due to the detection of Compton-scattered photons in the Tc-99m photopeak window, which originate from the In-111 emissions (cross talk) and from the Tc-99m emission (self-scatter). The standard triple-energy window (TEW) estimates the total scatter (self-scatter and cross talk) using one scatter window on either side of the Tc-99m photopeak window, but the estimate is biased due to the presence of unscattered photons in the scatter windows...
October 2016: Medical Physics
Jun Dang, Fang-Fang Yin, Tao You, Chunhua Dai, Deyu Chen, Jing Wang
PURPOSE: Current approaches using deformable vector field (DVF) for motion-compensated 4D-cone beam CT (CBCT) reconstruction typically utilize an isotropically smoothed DVF between different respiration phases. Such isotropically smoothed DVF does not work well if sliding motion exists between neighboring organs. This study investigated an anisotropic motion modeling scheme by extracting organ boundary local motions (e.g., sliding) and incorporated them into 4D-CBCT reconstruction to optimize the motion modeling and reconstruction methods...
October 2016: Medical Physics
George A Prenosil, Bernd Klaeser, Michael Hentschel, Markus Fürstner, Michael Berndt, Thomas Krause, Thilo Weitzel
PURPOSE: A PET/CT system's imaging capabilities are best described by its point spread function (PSF) in the spatial domain or equivalently by its modulation transfer function (MTF) in the spatial frequency domain. Knowing PSFs or MTFs is a prerequisite for many numerical methods attempting to improve resolution and to reduce the partial volume effect. In PET/CT, the observed PSF is a convolution of the system's intrinsic imaging capabilities including image reconstruction (PSF0) and the positron range function (PRF) of the imaged β(+) emitting isotope...
October 2016: Medical Physics
Brian Finney, Ryan C Fortenberry, Joseph S Francisco, Kirk A Peterson
In moving beyond the second row of the periodic table for molecules of astronomical and atmospheric significance, the exploration of sulfur and phosphorus chemistry is essential. Additionally, silicon is abundant in most astrophysical environments and is a major component of most rocky bodies. The triatomic molecule composed of each of these atoms is therefore a tantalizing candidate for spectroscopic characterization for astrophysical reasons as well as gaining further understanding into the chemical physics of molecules that are not carbon-based...
September 28, 2016: Journal of Chemical Physics
Fengyan Wang, Kopin Liu
A complete set of four polarization-dependent differential cross sections in the reactions of Cl + aligned-CHD3(v1=1,jK)→DCl(v=0)+CHD2(v1=1) is reported here for two different, rotationally polarized states with j = 1: specifically the jK=10 state prepared via the R(0) excitation and the 1±1 state via Q(1). In stark contrast to the complicated situation of the HCl(v) + CD3(v = 0) channel reported in Paper-I, the stereo-requirement of this isotopic channel for both polarized reactants appears quite straightforward and consistent with a direct rebound mechanism...
October 14, 2016: Journal of Chemical Physics
Fengyan Wang, Kopin Liu
When a CHD3 molecule is pumped to the C-H stretching-excited state by absorbing a linearly polarized infrared (IR) photon via the R(0) branch of the v1 = 1←0 transition, the rotational angular momentum j of the prepared state jK=10 preferentially lies in a plane perpendicular to the IR polarization axis εIR. By way of contrast, when the Q(1) branch is used, the state of jK=1±1 is prepared with j aligned along the direction of εIR. Reported here is a detailed study of the title reaction by actively controlling the collision geometries under these two IR-excitation schemes at collision energy Ec = 8...
October 14, 2016: Journal of Chemical Physics
Rajib Biswas, William Carpenter, Gregory A Voth, Andrei Tokmakoff
Infrared (IR) spectroscopy of the water O-H stretch has been widely used to probe both the local hydrogen-bonding structure and dynamics of aqueous systems. Although of significant interest, the IR spectroscopy of excess protons in water remains difficult to assign as a result of extensive and strong intermolecular interactions in hydrated proton complexes. As an alternate approach, we develop a mixed quantum-classical model for the vibrational spectroscopy of the excess proton in isotopically dilute water that draws on frozen proton-water clusters taken from reactive molecular dynamics trajectories of the latest generation multi-state empirical valence bond proton model (MS-EVB 3...
October 21, 2016: Journal of Chemical Physics
Zhiqiang Zhao, Shu Liu, Dong H Zhang
The time-dependent wave packet method has been employed to calculate state-to-state differential cross sections for the title reaction in full dimensions. It is found that the majority of H2O is produced in the first stretching excited states, with a large fraction of available energy for the reaction ending up as product internal motion. The differential cross sections for collision energy up to 0.4 eV are all peaked in the backward direction, but the width of the angular distribution increases considerably as the increase of collision energy...
October 7, 2016: Journal of Chemical Physics
Olga Gorlova, Joseph W DePalma, Conrad T Wolke, Antonio Brathwaite, Tuguldur T Odbadrakh, Kenneth D Jordan, Anne B McCoy, Mark A Johnson
We report the isotope-dependent vibrational predissociation spectra of the H2-tagged OH(-) ⋅ (H2O)n=2,3 clusters, from which we determine the strongly coordination-dependent energies of the fundamentals due to the OH groups bound to the ion and the intramolecular bending modes of the water molecules. The HOH bending fundamental is completely missing in the delocalized OH(-) ⋅ (H2O) binary complex but is recovered upon adding the second water molecule, thereby establishing that the dihydrate behaves as a hydroxide ion solvated by two essentially intact water molecules...
October 7, 2016: Journal of Chemical Physics
Tai-Na Wu, Kun-Hsien Lin, Ying-Ta Wu, Jing-Rong Huang, Jung-Tung Hung, Jen-Chine Wu, Chien-Yu Chen, Kuo-Ching Chu, Nan-Horng Lin, Alice L Yu, Chi-Huey Wong
Glycosphingolipids (GSLs) bearing the α-galactosyl head group and the acyl chain terminated with a phenyl derivative were found to be more potent than α-galactosyl ceramide (αGalCer) to stimulate both murine and human invariant natural killer T (iNKT) cells and to induce antibody isotope switch to IgG. In this study, we replaced the galactosyl group with glucose (αGlc) and its fluoro-analogs, and found that phenyl GSLs with αGlc (C34-Glc) and its fluoro-analog 6F-C34-Glc were stronger than those with αGal in stimulating human iNKT cells but weaker in mice...
October 26, 2016: ACS Chemical Biology
Tathyana Mar Amorim Franco, Subray S Hegde, John S Blanchard
The biosynthetic pathway of the branched-chain amino acids is essential for M. tuberculosis growth and survival. We report here the kinetic and chemical mechanism of the pyridoxal 5'-phosphate (PLP)-dependent branched-chain aminotransferase, IlvE, from M. tuberculosis (MtIlvE). This enzyme is responsible for the final step of the synthesis of the branched-chain amino acids isoleucine, leucine and valine. As seen in other aminotransferases, MtIlvE displays a ping-pong kinetic mechanism. pK values were identified from the pH dependence on V as well as V/K, indicating that the phosphate ester of the PLP cofactor, as well as the α-amino group from L-glutamate and the active site Lys204, play roles in acid-base catalysis and binding, respectively...
October 25, 2016: Biochemistry
Jacqueline E Gonzalez, Maciek R Antoniewicz
Engineered microbes offer a practical and sustainable alternative to traditional industrial approaches. To increase the economic feasibility of biological processes, microbial isolates are engineered to take up inexpensive feedstocks (including lignocellulosic biomass, syngas, methane, and carbon dioxide), and convert them into substrates of central metabolism and further into value-added products. To trace the metabolism of these feedstocks into products, isotopic tracers are applied together with isotopomer analysis techniques such as (13)C-metabolic flux analysis to provide a detailed picture of pathway utilization...
October 22, 2016: Current Opinion in Biotechnology
K E Hargan, N Michelutti, K Coleman, C Grooms, J M Blais, L E Kimpe, G Gilchrist, M Mallory, J P Smol
Seabirds that congregate in large numbers during the breeding season concentrate marine-derived nutrients to their terrestrial nesting sites, and these nutrients disperse and enhance production in nearby terrestrial, freshwater and marine ecosystems. In the Canadian Arctic, large seabird colonies (>100,000 breeding pairs) nest on cliff faces that drain directly in the ocean, ultimately returning the nutrients back to the marine environment from which they were derived. However, strong winds blowing up cliff faces could transport nutrients up in elevation and onto surrounding terrestrial and aquatic environments...
October 22, 2016: Science of the Total Environment
C Loredo, A Ordóñez, E Garcia-Ordiales, R Álvarez, N Roqueñi, P Cienfuegos, A Peña, N M Burnside
Abandoned and flooded mine networks provide underground reservoirs of mine water that can be used as a renewable geothermal energy source. A complete hydrochemical characterization of mine water is required to optimally design the geothermal installation, understand the hydraulic behavior of the water in the reservoir and prevent undesired effects such as pipe clogging via mineral precipitation. Water pumped from the Barredo-Figaredo mining reservoir (Asturias, NW Spain), which is currently exploited for geothermal use, has been studied and compared to water from a separate, nearby mountain mine and a river that receives mine water discharge and partially infiltrates into the mine workings...
October 22, 2016: Science of the Total Environment
Maria Kalafateli, Fred Wickham, Maria Burniston, Evangelos Cholongitas, Eleni Theocharidou, Matteo Garcovich, James O'Beirne, Rachel Westbrook, Gioacchino Leandro, Andrew K Burroughs, Emmanuel A Tsochatzis
: Current expressions based on serum creatinine concentration overestimate kidney function in cirrhosis leading to significant differences between "true" and calculated glomerular filtration rate (GFR). We compared the performance of MDRD-4, MDRD-6 and CKD-EPI with "true" GFR and the impact of this difference on MELD calculation. We subsequently developed and validated a GFR equation specifically for cirrhosis and compared the performance of the new derived formula with existing GFR formulas...
October 25, 2016: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
Sara J Marsteller, Natalya Zolotova, Kelly J Knudson
OBJECTIVES: Hypothetical models of socioeconomic organization in pre-Columbian societies generated from the rich ethnohistoric record in the New World require testing against the archaeological and bioarchaeological record. Here, we test ethnohistorian Maria Rostworowski's horizontality model of socioeconomic specialization for the Central Andean coast by reconstructing dietary practices in the Late Intermediate Period (c. AD 900-1470) Ychsma polity to evaluate complexities in social behaviors prior to Inka imperial influence...
October 25, 2016: American Journal of Physical Anthropology
Pyeong-Koo Lee, Soonyoung Yu, Hye Jung Chang, Hye Young Cho, Min-Ju Kang, Byung-Gon Chae
Spherical black carbon aggregates were frequently observed in dust dry deposition in Daejeon, Korea. They were tens of micrometers in diameter and presented a mixture of black carbon and several mineral phases. Transmission electron microscopy (TEM) observations with energy-dispersive X-ray spectroscopy (EDS) and selected area diffraction pattern (SADP) analyses confirmed that the aggregates were compact and included significant amounts of lead chromate (PbCrO4). The compositions and morphologies of the nanosized lead chromate particles suggest that they probably originated from traffic paint used in roads and were combined as discrete minerals with black carbon...
October 25, 2016: Scientific Reports
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