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Pouyan Ebrahimi, Javier Vilcáez
This research aimed to elucidate the effect of brine salinity and guar gum on the sorption and transport of Ba in dolomite rocks collected from the Arbuckle formation in Oklahoma, USA. Guar gum represents the most important organic additive used in viscosified fracturing fluids, and Ba constitutes the most common and abundant heavy metal found in unconventional oil and gas (UOG) wastewater. Batch experiments conducted using powdered dolomite rocks (500-600 μm particle size) revealed that at brine salinities of UOG wastewater, chloro-complexation reactions between Ba and Cl ions and pH changes that results from dolomite dissolution are the controlling factors of Ba sorption on dolomite...
March 12, 2018: Journal of Environmental Management
Baruch B Hertzog, Yael Kaufman, Debabrata Biswas, Miriam Ravins, Poornima Ambalavanan, Reuven Wiener, Veronique Angeli, Swaine L Chen, Emanuel Hanski
Bacteria use quorum sensing (QS) to regulate gene expression. We identified a group A Streptococcus (GAS) strain possessing the QS system sil, which produces functional bacteriocins, through a sequential signaling pathway integrating host and bacterial signals. Host cells infected by GAS release asparagine (ASN), which is sensed by the bacteria to alter its gene expression and rate of proliferation. We show that upon ASN sensing, GAS upregulates expression of the QS autoinducer peptide SilCR. Initial SilCR expression activates the autoinduction cycle for further SilCR production...
March 14, 2018: Cell Host & Microbe
Saisi Xue, A Daniel Jones, Leonardo Sousa, Jeff Piotrowski, Mingjie Jin, Cory Sarks, Bruce E Dale, Venkatesh Balan
Biochemical conversion of lignocellulosic biomass to liquid fuels requires pretreatment and enzymatic hydrolysis of the biomass to produce fermentable sugars. Degradation products produced during thermochemical pretreatment, however, inhibit the microbes with regard to both ethanol yield and cell growth. In this work, we used synthetic hydrolysates (SynH) to study the inhibition of yeast fermentation by water-soluble components (WSC) isolated from lignin streams obtained after extractive ammonia pretreatment (EA)...
2018: PloS One
Seungtaik Hwang, Arun Gopalan, Maximilian Hovestadt, Frank Piepenbreier, Christian Chmelik, Martin Hartmann, Randall Q Snurr, Jörg Kärger
Molecular diffusion is commonly found to slow down with increasing molecular size. Deviations from this pattern occur in some host materials with pore sizes approaching the diameters of the guest molecules. A variety of theoretical models have been suggested to explain deviations from this pattern, but robust experimental data are scarcely available. Here, we present such data, obtained by monitoring the chain length dependence of the uptake of n- alkanes in the zeolitic imidazolate framework ZIF-4. A monotonic decrease in diffusivity from ethane to n- butane was observed, followed by an increase for n- pentane, and another decrease for n- hexane...
March 15, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Anna Koziróg, Bogumił Brycki, Katarzyna Pielech-Przybylska
This study investigates the biological activity of two cationic gemini surfactants, hexamethylene-1,6-bis-( N , N -dimethyl- N -dodecylammonium bromide) C6 and pentamethylene-1,5-bis-( N , N -dimethyl- N -dodecyla,.mmonium bromide) C5, and their two neutral analogs, hexamethylene-1,6-bis-( N -methyl- N -dodecylamine) (A6) and pentamethylene-1,5-bis-( N -methyl- N -dodecylamine) (A5). Experiments were performed with Aspergillus brasiliensis , which is used in the standard tests for biocides. The minimal inhibitory concentration (MIC) values for conidia and mycelium were determined using the dilution method...
March 15, 2018: International Journal of Molecular Sciences
Ewa Erdmann, Marta Łabuda, Nestor Fabián Aguirre, Sergio Díaz-Tendero, Manuel Alcami
We present a complete exploration of the different fragmentation mechanisms of furan (C4H4O) operating at low and high energies. Three different theoretical approaches are combined to determine the structure of all possible reaction intermediates, many of them not described in previous studies, and a large number of pathways involving three types of fundamental elementary mechanisms: isomerization, fragmentation and H/H2 loss processes, this last one was not yet explored. Our results are compared with the existing experimental and theoretical investigations for furan fragmentation...
March 15, 2018: Journal of Physical Chemistry. A
Jianping Cao, Xu Zhang, Yinping Zhang
Dermal exposure to indoor gas-phase semi-volatile organic compounds (SVOCs) has recently received a great deal of attention, and this has included evaluating the role of clothing in this process. Several models have been developed to assess dermal exposure to SVOCs, based on the transient mass transfer of SVOCs from air to dermal capillaries. However, these models assume either that clothing completely retards SVOC transport, or that there is an air gap of constant thickness between the clothing and the surface of the skin, leading to significant errors in the model calculations...
March 15, 2018: Environmental Science & Technology
Haolan Zhao, Stéphane Clemmen, Ali Raza, Roel Baets
We report, to the best of our knowledge, the first demonstration of stimulated Raman spectroscopy enhanced by a nanophotonic integrated circuit. The Raman response of low-concentration dimethyl sulfoxide is evanescently probed via centimeter-long wire waveguides. A signal enhancement of close to five orders of magnitude, as compared to the case of on-chip spontaneous Raman scattering, is demonstrated. This significant enhancement factor allows for the use of continuous-wave lasers with milliwatt-level power and uncooled detectors and, therefore, sets the basis of future all-on-a-chip Raman spectrometers suitable for both gas and liquid detection...
March 15, 2018: Optics Letters
Renata C Gallagher, Laura Pollard, Anna I Scott, Suzette Huguenin, Stephen Goodman, Qin Sun
Disclaimer: These ACMG Standards are intended as an educational resource for clinical laboratory geneticists to help them provide quality clinical laboratory genetic services. Adherence to these Standards is voluntary and does not necessarily assure a successful medical outcome. These Standards should not be considered inclusive of all proper procedures and tests, or exclusive of others that are reasonably directed to obtaining the same results. In determining the propriety of any specific procedure or test, clinical laboratory geneticists should apply their professional judgment to the specific circumstances presented by the patient or specimen...
March 15, 2018: Genetics in Medicine: Official Journal of the American College of Medical Genetics
Heather M Young, Fumin Guo, Rachel L Eddy, Geoffrey Maksym, Grace Parraga
Ventilation heterogeneity is a hallmark finding in obstructive lung disease and may be evaluated using a variety of methods including multiple-breath gas-washout and pulmonary imaging. Such methods provide an opportunity to better understand the relationships between structural and functional abnormalities in the lungs, and their relationships with important clinical outcomes. We measured ventilation heterogeneity and respiratory impedance in 100 subjects (50 asthmatics, 22 ex-smokers and 28 COPD), using oscillometry and hyperpolarized3 He magnetic resonance imaging (MRI) and determined their relationships with quality-of-life scores and disease control/exacerbations...
March 15, 2018: Journal of Applied Physiology
Stephen E McGowan, Diann M McCoy
Secondary alveolar septa are mostly generated after birth in humans and in mice this is completely accomplished postnatally, when mechanical stresses vary as airspace pressure oscillates. Alveolar mesenchymal cells deposit elastic fibers which limit cellular strain, but while the elastic fiber network is incomplete, this function is also served by the intracellular cytoskeleton. Intermediate filament proteins support deformation during cellular division and migration, which occur during septal elongation. Because platelet-derived growth factor-alpha (PDGFRα) signaling is essential for alveolar septation, we hypothesized that neuropilin-1 (NRP1) may link PDGFRα to cytoskeletal deformation...
March 15, 2018: American Journal of Physiology. Lung Cellular and Molecular Physiology
F Camargo, R Schmidt, J D Whalen, R Ding, G Woehl, S Yoshida, J Burgdörfer, F B Dunning, H R Sadeghpour, E Demler, T C Killian
We report spectroscopic observation of Rydberg polarons in an atomic Bose gas. Polarons are created by excitation of Rydberg atoms as impurities in a strontium Bose-Einstein condensate. They are distinguished from previously studied polarons by macroscopic occupation of bound molecular states that arise from scattering of the weakly bound Rydberg electron from ground-state atoms. The absence of a p-wave resonance in the low-energy electron-atom scattering in Sr introduces a universal behavior in the Rydberg spectral line shape and in scaling of the spectral width (narrowing) with the Rydberg principal quantum number, n...
February 23, 2018: Physical Review Letters
Nazim Boudjada, Gideon Wachtel, Arun Paramekanti
Recent experiments have explored two-dimensional electron gases (2DEGs) at oxide (111) surfaces and interfaces, finding evidence for hexagonal symmetry breaking in SrTiO_{3} at low temperature. We discuss many-body instabilities of such (111) 2DEGs, incorporating multiorbital interactions in the t_{2g} manifold which can induce diverse magnetic and orbital orders. Such broken symmetries may partly account for the observed nematicity, cooperating or competing with phonon mechanisms. We present an effective field theory for the interplay of magnetism and nematic charge order, and discuss implications of the nematicity for transport and superconductivity in (111) 2DEGs...
February 23, 2018: Physical Review Letters
Junjun Xu, Qiang Gu, Erich J Mueller
We analyze an experimentally realizable model of bosons in a zigzag optical lattice, showing that, by rapidly modulating the magnetic field, one can tune interaction parameters and realize an analog of the Haldane phase. We explain how quantum gas microscopy can be used to detect this phase's nonlocal string order and its topological edge states. We model the detection process. We also find that this model can display supersolid correlations, but argue that they only occur at parameter values which would be challenging to realize in an experiment...
February 23, 2018: Physical Review Letters
Kazuya Fujimoto, Ryusuke Hamazaki, Masahito Ueda
By studying the coarsening dynamics of a one-dimensional spin-1 Bose-Hubbard model in a superfluid regime, we analytically find an unconventional universal dynamical scaling for the growth of the spin correlation length, which is characterized by the exponential integral unlike the conventional power law or simple logarithmic behavior, and numerically confirmed with the truncated Wigner approximation.
February 16, 2018: Physical Review Letters
Valentin V Karasiev, James W Dufty, S B Trickey
Realizing the potential for predictive density functional calculations of matter under extreme conditions depends crucially upon having an exchange-correlation (XC) free-energy functional accurate over a wide range of state conditions. Unlike the ground-state case, no such functional exists. We remedy that with systematic construction of a generalized gradient approximation XC free-energy functional based on rigorous constraints, including the free-energy gradient expansion. The new functional provides the correct temperature dependence in the slowly varying regime and the correct zero-T, high-T, and homogeneous electron gas limits...
February 16, 2018: Physical Review Letters
Melissa P Woodard, Scott T Akin, Collin J Dibble, Michael A Duncan
Ultra-small chromium oxide nanoclusters produced by laser vaporization in a fast flowtube reactor are ligand-coated by gas phase reactions with acetonitrile vapor and then captured in a cold trap and transferred to solution. The resulting clusters are characterized with mass spectrometry, UV-visible absorption and emission, infrared spectroscopy, and surface-enhanced Raman spectroscopy (SERS). According to mass spectrometry, clusters of the form CrxOy(MeCN)z are produced in the size range of x  10 and y < 25...
March 15, 2018: Journal of Physical Chemistry. A
B Serrano Falcón, M Megía Sánchez, A Ruiz de León, E Rey
BACKGROUND: Beer has been related to gastroesophageal reflux (GER) and dyspepsia, based on its alcohol and gas content. The aim of this study is to evaluate the association between moderate consumption of traditional and alcohol-free beer and upper digestive symptoms, gastric accommodation and GER. METHODS: Healthy adults without frequent gastrointestinal symptoms and GER disease were included. The intervention involved administration of traditional beer to 10 subjects (substudy 1) and alcohol-free beer to 20 (substudy 2); control intervention entailed administration of water...
March 15, 2018: Neurogastroenterology and Motility: the Official Journal of the European Gastrointestinal Motility Society
Thomas J Wood, Joshua W Makepeace, William I F David
Manganese and its nitrides have recently been shown to co-catalyse the ammonia decomposition reaction. The nitriding reaction of manganese under ammonia decomposition conditions is studied in situ simultaneously by thermogravimetric analysis and neutron diffraction. Combining these complementary measurements has yielded information on the rate of manganese nitriding as well as the elucidation of a gamut of different manganese nitride phases. The neutron diffraction background was shown to be related to the extent of the ammonia decomposition and therefore the gas composition...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Kentaro Teramura, Tsunehiro Tanaka
Artificial photosynthesis has recently drawn an increasing amount of attention due to the fact that it allows for direct solar-to-chemical energy conversion. However, one of the basic steps of this process, namely the reduction of CO2 by H2 O to afford O2 and CO2 reduction products (CO2 RPs) such as HCOOH, CO, HCHO, CH3 OH, and CH4 , is very difficult to achieve. In contrast to the CO2 reduction in plants and homogenous systems, the reduction of CO2 to CO2 RPs over heterogeneous photocatalysts was challenged by the competing reduction of H+ to H2 ...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
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