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Gas Hydrate

Pasquale Giorio, Gianpiero Guida, Carmela Mistretta, Mohamed Houssemeddine Sellami, Marco Oliva, Paola Punzo, Paolo Iovieno, Carmen Arena, Anna De Maio, Stefania Grillo, Rossella Albrizio
Mediterranean tomato landraces adapted to arid environments represent an option to counteract drought, and to address the complexity of responses to water deficit and recovery, which is a crucial component of plant adaptation mechanisms. We investigated physiological, biochemical and molecular responses of two Mediterranean tomato landraces, "Locale di Salina" (Lc) and "Pizzutello di Sciacca" (Pz) under two dehydration periods and intermediate rehydration in greenhouse pot-experiments. Relationship between CO2 assimilation and stomatal conductance under severe water stress (gs < 0...
August 11, 2018: Plant Biology
Lorenz Kranabetter, Paul Martini, Norbert Gitzl, Martin Kuhn, Fatima Saleem, Bilal Rasul, Masoomeh Mahmoodi Darian, Elias Jabbour Al Maalouf, Ivan Sukuba, Alexander Kaiser, Marcelo Goulart, Diethard K Böhme, Paul Scheier
We report an experimental study of water clusters as guests in interactions with clusters of adamantane (Ad) as hosts that occur in doped helium droplets at extremely low temperatures. Separate experiments with pure water as dopant showed ready formation of a distribution of water clusters (H2O)mH+ that peaks at m = 11 and extends beyond m = 100 with local maxima at m = 4, 11, 21, 28 and 30 with (H2O)21H+ being the most anomalous and showing the greatest stability with respect to clusters immediately adjacent in water content...
August 10, 2018: Physical Chemistry Chemical Physics: PCCP
Sérgio R Domingos, Melanie Schnell
New insights on the structural intricacies of solvated sunscreen compounds are presented. Using high-resolution rotational spectroscopy with supersonic jets and quantum chemistry calculations we navigate the conformational space of oxybenzone and oxybenzone-water clusters. We unambiguously assign the global minimum structure, resolving any prevailing ambiguities, and locate the primary hydration sites of the ground state enol conformer. Two micro-solvated molecular models of oxybenzone are validated by rotational spectroscopy of isotopically-enriched species...
August 9, 2018: Journal of Physical Chemistry Letters
Svetlana Bortnikova, Nataliya Yurkevich, Anna Devyatova, Olga Saeva, Olga Shuvaeva, Alexei Makas, Mikhail Troshkov, Natalya Abrosimova, Maksim Kirillov, Tatyana Korneeva, Tatyana Kremleva, Nikolay Fefilov, Gulnara Shigabaeva
This paper presents experimental data that revealed the potential for chemical element transport by low-temperature vapor-gas streams. The study was conducted on sulfide waste heap sites located in the Kemerovo region, Russia. Condensates of vapor-gas streams were collected and analyzed in the air above the waste heaps and during laboratory experiments using samplers specially designed for this purpose. The gas streams from a waste heaps are complex mixtures consisting of water vapor, sulfur- and selenium-containing compounds (sulfur dioxide SO2 , dimethyl sulfide C2 H6 S, carbon disulfide CS2 , dimethyl disulfide C2 H6 S2 , dimethyl selenide C2 H6 Se, and dimethyl diselenide C2 H6 Se2 ), elemental sulfur (S6 , S7 , and S8 ) and various chemical elements, including rock-forming elements (Ca, Mg, Na, K, Si, Fe, Al, and Mn), metals (Cu, Zn, Pb, Ni, and Sn), and metalloids (As, Te, and Sb)...
August 3, 2018: Science of the Total Environment
Jayangika N Dahanayake, Katie R Mitchell-Koch
Solvation is critical for protein structural dynamics. Spectroscopic studies have indicated relationships between protein and solvent dynamics, and rates of gas binding to heme proteins in aqueous solution were previously observed to depend inversely on solution viscosity. In this work, the solvent-compatible enzyme Candida antarctica lipase B, which functions in aqueous and organic solvents, was modeled using molecular dynamics simulations. Data was obtained for the enzyme in acetonitrile, cyclohexane, n- butanol, and tert- butanol, in addition to water...
2018: Frontiers in Molecular Biosciences
Yu Wang, Jian-Hua Kang, Qian-Yong Liang, Xue-Bao He, Jian-Jun Wang, Mao Lin
We analyzed the data obtained from field observations on a gas hydrate drilling area in Dongsha of northern South China Sea (SCS) in middle May (before drilling) and early October (after drilling) in 2013. The variation in the phytoplankton communities and biomass as well as the impacts of environmental factors including dissolved methane was studied. Results indicated that the gas hydrate drilling area in Dongsha, SCS exhibited a typical low-nutrients low-chlorophyll a (LNLC) environment accompanied with low phytoplankton abundance...
August 2018: Marine Pollution Bulletin
Itai Schlesinger, Uri Sivan
Understanding the solvation layer of hydrophobic surfaces is essential for elucidating the interaction between hydrophobic surfaces in aqueous solutions. Despite their importance, little is known on these layers due to the lack of lateral resolution in spectroscopic or scattering experiments and probe instability in the static scanning probe methods used in most experiments. Using a high-resolution FM-AFM with stiff cantilevers and hydrophilic tips, we overcome this instability to provide the first detailed 3d maps of the solvation/hydration layer of two archetypal hydrophobic surfaces: graphite (HOPG) and self-assembled fluoro-alkane monolayer (FDTS)...
August 8, 2018: Journal of the American Chemical Society
H Sugi, T Akimoto, S Chaen
No abstract text is available yet for this article.
June 8, 2018: Micron: the International Research and Review Journal for Microscopy
Joan M Bernhard, Giuliana Panieri
Foraminifera in sediments exposed to gas-hydrate dissociation are not expected to have cellular adaptations that facilitate inhabitation of chemosynthesis-based ecosystems because, to date, there are no known endemic seep foraminifera. To establish if foraminifera inhabit sediments impacted by gas-hydrate dissociation, we examined the cellular ultrastructure of Melonis barleeanus (Williamson, 1858) from the Vestnesa gas hydrate province (Arctic Ocean, west of Svalbard at ~79 °N; ~1200-m depth; n = 4)...
July 13, 2018: Scientific Reports
Dingkang Chen, Zhiyun Du, Zhirong Lin, Ping Su, Hanyi Huang, Zhirong Ou, Wanyi Pan, Shiya Huang, Kun Zhang, Xi Zheng, Li Lin, Lanyue Zhang
Angelica pubescens, a plant of the family Umbelliferae, has been widely used as traditional Chinese medicine for the treatment of many diseases; however, there has been minimal modern research focused on the pharmacological activity of oils extracted from Angelica pubescens, in particular, the potential anti-photoaging effects. Therefore, in the present study, we analyzed the chemical composition of Angelica pubescens oil (AO) and evaluated its bioactivity against photoaging in ultraviolet (UV) -B radiation-induced hairless mice...
July 11, 2018: Chemistry & Biodiversity
Peng Zhang, Qingbai Wu, Cuicui Mu, Xueping Chen
The concentration of gas has been confirmed as a key factor dominating hydrate nucleation. In this study, CO2 hydrates were formed in pure water and a sodium dodecyl sulphate (SDS) solution using a temperature reduction method under constant pressure at different temperatures. The dissolving properties of CO2 throughout the whole induction period were investigated in detail. The experimental results showed that the 'memory effect' of hydrate might not be attributed to residual water structures after hydrate dissociation...
July 11, 2018: Scientific Reports
Junting Qiu, Shinnosuke Ishizuka, Kenichi Tonokura, Shinichi Enami
Secondary organic aerosol (SOA) found in polluted mega-cities contains benzoic acid (BA) as a major organic acid in addition to a variety of species including alkenes. In polluted air, ozone could be a major oxidizer for SOA and induces subsequent reactions involving Criegee intermediates (CIs, carbonyl oxide, RR'C• -O-O• /RR'C═O+ -O- ) formed by the -C═C- + O3 reaction at the gas/liquid interface. The possibility that abundant BA could be an effective scavenger of CIs at the interface remains to be investigated by direct experiments...
August 2, 2018: Journal of Physical Chemistry. A
Andrey M Kuznetsov, Alexey N Masliy, Gregory V Korshin
Thermodynamic and structural aspects of the hydration of Pb(II) ions were explored based on DFT calculations combined with the supermolecular/continuum solvent model. Hydration of Pb(II) was considered as the formation of Pb(H2 O)n 2+ aqua complexes (n=6-9) from the gas phase Pb(II) ion. Hexa- and hepta-aqua Pb(II) complexes were shown to exhibit the hemidirected symmetry, while those containing eight and nine water molecules are characterized by the holodirected symmetry. The calculations showed that because Pb(H2 O)n 2+ complexes with six to nine water molecules have comparable thermodynamic stabilities, such complexes are likely to coexist in aqueous solutions...
July 4, 2018: Journal of Molecular Modeling
Z Blossom Yan, Alan P Young, Gillian R Goward
Perfluorosulfonic acid (PFSA) materials have been used in polymer electrolyte membrane fuel cells (PEMFCs) as electrolyte materials due to their mechanical durability and high proton conductivity. To understand the fundamental chemistry at a molecular level in material performance properties, we have developed and validated method for evaluating local dynamics using 19F double-quantum solid-state nuclear magnetic resonance (ssNMR) spectroscopy. The local dynamics information can be separated and analyzed in terms of fluorine interactions with respect to the different temperatures and hydration levels...
July 18, 2018: Physical Chemistry Chemical Physics: PCCP
James L Lawrence, Hussam Hindi
A 41-year-old female presented to the emergency department with nausea, vomiting, and diarrhea. Five days prior to this, she tested positive for influenza type A in an urgent care clinic and received Tamiflu. She also complained of generalized weakness in her extremities. Her initial labs were concerning for a grossly elevated hemoglobin and hematocrit despite adequate fluid resuscitation. Her condition continued to worsen as she developed distal cyanosis in all of her extremities and pulselessness. She was treated with IV hydration, bicarbonate, heparin, vasopressors, albumin replacement, Tamiflu, and phlebotomy...
April 30, 2018: Curēus
Yingying Huang, Keyao Li, Xue Jiang, Yan Su, Xiaoxiao Cao, Jijun Zhao
Methane hydrate is not only the predominant natural deposits of permafrost and continental margins of Earth but also the dominant methane-containing phase in the nebula and major moons of gas giants. Depending on the surrounding environment (mainly pressure), seven methane hydrate phases have been discovered by experiment or predicted by computer simulation, such as clathrate methane hydrates I, II, H, and K, and filled-ice methane hydrates III, IV, and V. Using extensive Monte Carlo packing algorithm and density functional theory optimization, here we predict a partial clathrate methane hydrate VI built by basic units of 42 62 water bowl encapsulating a methane molecule, which is dynamically stable from the computed phonon dispersion...
July 19, 2018: Journal of Physical Chemistry. A
Murat Kılıç, J Paul Devlin, Nevin Uras-Aytemiz
The catalytic action of NH3 within the all-vapor approach for instant clathrate hydrate (CH) formation is studied using both FTIR spectroscopy and ab initio molecular dynamics simulations. A unique property of NH3 , namely, the rapid abundant penetration and occupation of the water network, creates defects, particularly Bjerrum D-defects, in the hydrate frame that are generally stabilized by guest NH3 molecules in the cages. Furthermore, insertion of NH3 seriously disturbs the hydrate network where the guest NH3 molecules also make fluxional H-bonds with the host water molecules...
June 21, 2018: Journal of Chemical Physics
Filip Moučka, Jiří Kolafa, Martin Lísal, William R Smith
We present a molecular-level simulation study of CaCl2 in water and crystalline hydrates formed by CaCl2 at ambient (298.15 K, 1 bar) conditions and at a high-temperature high-pressure state (365 K, 275 bars) typical of hydraulic fracturing conditions in natural-gas extraction, at which experimental properties are poorly characterized. We focus on simulations of chemical potentials in both solution and crystalline phases and on the salt solubility, the first time to our knowledge that such properties have been investigated by molecular simulation for divalent aqueous electrolytes...
June 14, 2018: Journal of Chemical Physics
Martin Svoboda, Martin Lísal
To address a high salinity of flow-back water during hydraulic fracturing, we use molecular dynamics (MD) simulations and study the thermodynamics, structure, and diffusion of concentrated aqueous salt solution in clay nanopores. The concentrated solution results from the dissolution of a cubic NaCl nanocrystal, immersed in an aqueous NaCl solution of varying salt concentration and confined in clay pores of a width comparable to the crystal size. The size of the nanocrystal equals to about 18 Å which is above a critical nucleus size...
June 14, 2018: Journal of Chemical Physics
H Sugi, T Akimoto, S Chaen
Although more than 50 years have passed since the monumental discovery of Huxley and Hanson that muscle contraction results from relative sliding between actin and myosin filaments, coupled with ATP hydrolysis, the mechanism underlying the filament sliding still remains to be a mystery. It is generally believed that the myofilament sliding is caused by cyclic attachment-detachment between myosin heads in myosin filaments and myosin-binding sites in actin filaments. Attempts to prove the myosin head movement using techniques of X-ray diffraction and chemical probes attached to myosin heads have failed to obtain clear results because of the asynchronous nature of myosin head movement...
June 5, 2018: Micron: the International Research and Review Journal for Microscopy
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