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Gas Hydrate

Christoph Strangfeld, Carsten Prinz, Felix Hase, Sabine Kruschwitz
Four cement-based and four calcium-sulphate-based screed types are investigated. The samples have a diameter of 300 mm and a height of 35 or 70 mm. Up to ten humidity sensors are embedded directly during the concreting of the screed samples. Thus, the humidity over the sample height is monitored during hardening, hydration, evaporation, and oven drying. Furthermore, the screed samples are weighed during every measurement to determine the total mass and the corresponding moisture loss. To define the pore system precisely, mercury intrusion porosimetry as well as gas adsorption is performed...
December 2018: Data in Brief
Bohan Sun, Richard N McCay, Shivam Goswami, Yadong Xu, Cheng Zhang, Yun Ling, Jian Lin, Zheng Yan
Soft on-skin electronics have broad applications in human healthcare, human-machine interface, robotics, and others. However, most current on-skin electronic devices are made of materials with limited gas permeability, which constrain perspiration evaporation, resulting in adverse physiological and psychological effects, limiting their long-term feasibility. In addition, the device fabrication process usually involves e-beam or photolithography, thin-film deposition, etching, and/or other complicated procedures, which are costly and time-consuming, constraining their practical applications...
October 10, 2018: Advanced Materials
Suhang He, Frank Biedermann, Nina Vankova, Lyuben Zhechkov, Thomas Heine, Roy E Hoffman, Alfonso De Simone, Timothy T Duignan, Werner M Nau
The accurate dissection of binding energies into their microscopic components is challenging, especially in solution. Here we study the binding of noble gases (He-Xe) with the macrocyclic receptor cucurbit[5]uril in water by displacement of methane and ethane as 1 H NMR probes. We dissect the hydration free energies of the noble gases into an attractive dispersive component and a repulsive one for formation of a cavity in water. This allows us to identify the contributions to host-guest binding and to conclude that the binding process is driven by differential cavitation energies rather than dispersion interactions...
October 8, 2018: Nature Chemistry
Neetika Rawat, Aishwarya Kar, A Bhattacharyya, A K Yadav, D Bhattacharyya, S N Jha, P Kumar, S K Nayak, B S Tomar
The assessment of cucurbituril (CBn) for selective removal of actinides from nuclear waste streams requires comprehensive understanding of binding parameters and coordination of these complexes. The present work is the first experimental report on complexation of actinide ion with Cucurbit[5]uril (CB5) in solution. The thermodynamic parameters (ΔG, ΔH and ΔS) for complexation of CB5 with U(VI) in formic acid water medium were determined using microcalorimetry and UV-Vis spectroscopy. The enthalpy and entropy of complexation revealed the partial binding of U(VI) to CB5 portal...
September 19, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Cristobal Perez, Iker León, Alberto Lesarri, Brooks H Pate, Rodrigo Martínez, Judith Millán, José A Fernández
Weaker intermolecular forces permit expanded isomerization alternatives for molecular aggregation, as observed for the prototype models of the aniline trimer (An3) and the monohydrated aniline dimer (An2-W) when compared to the phenol trimer. These isolated trimers were generated in a jet-cooled neon expansion and probed using broadband (chirped-pulsed) microwave spectroscopy. Three isomers of the aniline trimer and two isomers of the hydrated dimer were detected and characterized in the spectrum. In the homotrimer the weak N-H···N hydrogen bonds are assisted by subtle combinations of N-H···Pi and C-H···Pi interactions, producing several competing low-lying ring species in the gas phase...
October 3, 2018: Angewandte Chemie
Angelique Jarry, Sandrine Ricote, Aaron Geller, Christopher Pellegrinelli, Xiaohang Zhang, David M Stewart, Ichiro Takeuchi, Eric D Wachsman, Ethan J Crumlin, Bryan W Eichhorn
Performance of Proton-Solid Oxide Fuel Cells (H+-SOFC) is governed by ion transport through solid/gas interfaces. Major breakthroughs are then intrinsically linked to a detailed understanding of how parameters tailoring bulk proton conductivity affect surface chemistry in situ, at an early stage. In this work, we studied proton and oxygen transport at the interface between H+-SOFC electrolyte BaCexZr0.9-xY0.1O2.95 (x = 0; 0.2; 0.9) thin films and the gas (100 mtorr of H2O and O2) by using synchrotron-based ambient pressure X-ray photoelectron spectroscopy (APXPS) at operating temperature (>400°C)...
October 3, 2018: ACS Applied Materials & Interfaces
Nianxiang Qiu, Xiaojing Bai, Ningru Sun, Xiaohui Yu, Longbin Yang, Yanjun Li, Minghui Yang, Qing Huang, Shiyu Du
The cage occupancy plays a crucial role in thermodynamic stability of clathrate hydrates and is an important quantity for understanding the CO2-CH4 replacement phenomenon. In this work, the occupancy isotherms of pure CH4, pure CO2 and their mixture in sI and sII hydrates are studied by GCMC+MD simulations. The adsorption of CH4 and CO2+CH4 in the sI and sII hydrates are found to exhibit the one-site Langmuir-type adsorption behavior. The calculated occupancy ratio θL/θS and the separation factor of CO2 to CH4 vary with the temperature and pressure, and provide the prerequisite information about CH4 recovery yield at different experimental conditions for the CO2-CH4 gas exchange process...
October 2, 2018: Journal of Physical Chemistry. B
Zhimin Chen, Liang Quan, Haiting Zhou, Yongfeng Zhao, Peng Chen, Lin Hu, Zhuo Yang, Changjiang Hu, Dong Cao
ETHNOPHARMACOLOGICAL RELEVANCE: Curcuma Longa Radix (Huangsiyujin in Chinese, HSYJ) has been used in clinical for thousands of years as a traditional Chinese medicine (TCM) and has the effects of invigorating the blood circulation, relieving pain, promoting qi circulation and relieving depression, besides, it is able to clear heart heat and cool blood and cure jaundice. The study aims to determine the active fractions of HSYJ for promotion of blood circulation and relief of pain, and to identify their chemical constituents...
September 27, 2018: Journal of Ethnopharmacology
Mahmood Khan, Keith Manuel, Brooke Vegas, Shikha Yadav, Roxana Hemmati, Zaina Al-Mohtaseb
OBJECTIVES: To report the successful treatment of persistent corneal epithelial defects that failed to respond to alternative treatment methods using extended wear of three different rigid gas-permeable scleral lenses. METHODS: Eight eyes of eight patients with persistent corneal epithelial defects were treated with Blanchard Onefit 2.0 Scleral lens, BostonSight Scleral lens, and BostonSight PROSE device and were observed for defect resolution and improvement in best-corrected visual acuity over the duration of treatment...
September 25, 2018: Contact Lens & Anterior Eye: the Journal of the British Contact Lens Association
Alexey Portnov, Jürgen Mienert, Monica Winsborrow, Karin Andreassen, Sunil Vadakkepuliyambatta, Peter Semenov, Valery Gataullin
Geophysical data from the South Kara Sea reveal U-shaped erosional structures buried beneath the 50-250 m deep seafloor of the continental shelf across an area of ~32 000 km2 . These structures are interpreted as thermokarst, formed in ancient yedoma terrains during Quaternary interglacial periods. Based on comparison to modern yedoma terrains, we suggest that these thermokarst features could have stored approximately 0.5 to 8 Gt carbon during past climate warmings. In the deeper parts of the South Kara Sea (>220 m water depth) the paleo thermokarst structures lie within the present day gas hydrate stability zone, with low bottom water temperatures -1...
September 25, 2018: Scientific Reports
Zhengcai Zhang, Peter G Kusalik, Guang-Jun Guo
By investigating the aqueous solution properties of several hydrate guests with molecular simulations, we find that with increasing guest concentration, the guest's hydration shell becomes more ordered and the system entropy decreases. A common critical value of the self-diffusion coefficient of different guest molecules is identified, below which hydrates will nucleate very readily.
October 3, 2018: Physical Chemistry Chemical Physics: PCCP
Xianbin Huang, Haokun Shen, Jinsheng Sun, Kaihe Lv, Jingping Liu, Xiaodong Dong, Shaojie Luo
Shale hydration is the main reason causing wellbore instability in oil and gas drilling operations. In this study, nanoscale laponite as a shale inhibitor was employed to stabilize wellbores. The inhibition property of laponite suspensions was evaluated by an immersion experiment, linear swelling measurement, and a shale recovery test. Then the shale inhibition mechanism was studied by using capillary suction time (CST) measurement, a thixotropy study, plugging performance evaluation, and related theoretical analysis...
October 3, 2018: ACS Applied Materials & Interfaces
Junting Qiu, Shinnosuke Ishizuka, Kenichi Tonokura, Agustín J Colussi, Shinichi Enami
Biogenic monoterpenes are major sources of Criegee intermediates (CIs) in the troposphere. Recent studies underscored the importance of their heterogeneous chemistry. The study of monoterpene CI reactions on liquid surfaces, however, is challenging due to the lack of suitable probes. Here, we report the first mass spectrometric detection of the intermediates and products, which include labile hydroperoxides, from reactions of CIs of representative monoterpenes (α-terpinene, γ-terpinene, terpinolene, d-limonene, α-pinene) with water, cis-pinonic acid (CPA) and octanoic acid (OA) on the surface of liquid microjets...
October 4, 2018: Journal of Physical Chemistry. A
Jan Košata, Padryk Merkl, Pattanasak Teeratchanan, Andreas Hermann
The formation of gas hydrates and clathrates critically depends on the interaction between the host water network and the guest gas species. Density functional calculations can struggle to quantitatively capture these dispersion-type interactions. Here, we report wave function-based calculations on hydrogen hydrates that combine periodic Hartree-Fock with a localized treatment of electronic correlation. We show that local second-order Møller-Plesset perturbation theory (LMP2) reproduces the stability of the different filled-ice-like hydrates in excellent agreement with experimental data...
September 20, 2018: Journal of Physical Chemistry Letters
Esam A Orabi, Ann M English
Noncovalent interactions between Met and aromatic residues define a common Met-aromatic motif in proteins. Met oxidation to MetOn (n = 1 sulfoxide, n = 2 sulfone) alters protein stability and function. To predict the chemical and physical consequences of such oxidations, we modeled the chemistry and redox properties of MetOn-aromatic complexes in depth for comparison with our Met-aromatic models (E. A. Orabi and A. M. English, J. Phys. Chem. B, 2018, 122, 3760). We describe here ab initio quantum mechanical calculations at the MP2(full)/6-311++G(d,p) level of theory on complexes of MetOn (n = 1, 2; modeled by Me2SO and Me2SO2) with models of the side-chains of Phe (benzene, toluene), Trp (indole, 3-methylindole), Tyr (phenol, 4-methylphenol) and His (imidazole, 4-methylimidazole)...
September 12, 2018: Physical Chemistry Chemical Physics: PCCP
Mahmood Barani, Mohammad Mirzaei, Masoud Torkzadeh-Mahani, Mohammad Hadi Nematollahi
Phytochemicals like Lawsone have some drawbacks that stem from their poor solubility. Low solubility in aqueous mediums results in low bioavailability, poor permeability and instability of phytochemical compounds in biological environments. The aim of this study was to design nanoniosomes containing Lawsone (Law) using non-ionic surfactants and cholesterol. Niosomes were prepared by thin film hydration method (TFH). Then, they were loaded with Henna extract (HLaw) and standard Lawsone (SLaw), and two resulted formulations were compared...
September 2018: Daru: Journal of Faculty of Pharmacy, Tehran University of Medical Sciences
Jingpeng Hou, Dongsheng Bai, Wei Zhou
Elastic materials are candidates for process intensification of gas storage by forming gas hydrate. In this work, molecular dynamics simulations of hydrate nucleation in elastic silica double layers were performed to study the effect of elastic confined spaces on hydrate formation. It is found that in narrow confined spaces, hexagonal rings dominated the hydrogen bond network of water molecules established rapidly by a multisite nucleation mechanism. With molecules added, a bilayer water structure was formed finally because elastic space can adapt the volume expansion...
September 18, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Hengqing Shen, Zhongming Chen, Huan Li, Xi Qian, Xuan Qin, Wenxiao Shi
Despite their crucial roles in health and climate concerns, the gas-particle partitioning of carbonyl compounds is poorly characterized in the ambient atmosphere. In this study, we investigate their partitioning by simultaneously measuring six carbonyl compounds (formaldehyde, acetaldehyde, acetone, propionaldehyde, glyoxal, and methylglyoxal) in the gas and particle phase at an urban site in Beijing. The field-derived partitioning coefficients ( Kp f ) are in the range of 10-5 -10-3 m3 μg-1 , and the corresponding effective Henry's law coefficients ( KH f ) should be 107 -109 M atm-1 ...
October 2, 2018: Environmental Science & Technology
Zhenzhou Lin, Heping Pan, Hui Fang, Wenli Gao, Dongming Liu
The Muli area is the only permafrost region on the Chinese mainland wherein gas hydrates have been discovered. The gas hydrates are present in the fractures and pore spaces of the host rocks with a lamellar or micro-disseminated structure. By combining conventional and image logs, we describe the thickness of the permafrost layer and the well log responses of the gas hydrate reservoir, and calculate the porosity and gas hydrate saturation. We then analyze the advantages and disadvantages of different logging methods for evaluating gas hydrate reservoirs...
August 22, 2018: Scientific Reports
Hideki Tanaka, Takuma Yagasaki, Masakazu Matsumoto
We apply a statistical mechanical theory on clathrate hydrates to an exploration of the phase behaviors of hydrocarbon and noble gas clathrate hydrates. Two- and three-phase coexisting conditions in the whole space of thermodynamic variables (temperature, pressure, and composition) are evaluated only from intermolecular interactions for water and guest species. The occupancy of guest molecules in various types of cages is also calculated. We find that a small difference in the guest size gives rise to a rich variety of phase behaviors, notably for the shape of the two-phase boundary and the occupancy...
August 21, 2018: Journal of Chemical Physics
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