scholarly journals Retracted Article: Effect of temperature and large guest molecules on the C–H symmetric stretching vibrational frequencies of methane in structure H and I clathrate hydrates

RSC Advances ◽  
2018 ◽  
Vol 8 (6) ◽  
pp. 3237-3242 ◽  
Author(s):  
Go Fuseya ◽  
Satoshi Takeya ◽  
Akihiro Hachikubo
Keyword(s):  
Temperature Effects ◽  
Vibrational Frequencies ◽  
Clathrate Hydrates ◽  
Effect Of Temperature ◽  
Guest Molecules ◽  
Retracted Article

Temperature effects on C–H symmetric stretching frequencies of CH4 in water cages of sI and sH clathrate hydrates were clarified.

scholarly journals Effect of temperature and large guest molecules on the C–H symmetric stretching vibrational frequencies of methane in structure H and I clathrate hydrates

RSC Advances ◽  
2020 ◽  
Vol 10 (30) ◽  
pp. 17473-17478
Author(s):  
Go Fuseya ◽  
Satoshi Takeya ◽  
Akihiro Hachikubo
Keyword(s):  
Temperature Effect ◽  
Vibrational Frequencies ◽  
Clathrate Hydrates ◽  
Effect Of Temperature ◽  
Guest Molecules

Temperature effect on C–H symmetric stretching frequencies of CH4 in water cages of sI and sH clathrate hydrates were clarified.

scholarly journals Retraction: Effect of temperature and large guest molecules on the C–H symmetric stretching vibrational frequencies of methane in structure H and I clathrate hydrates

RSC Advances ◽  
2020 ◽  
Vol 10 (29) ◽  
pp. 16904-16904
Author(s):  
Go Fuseya ◽  
Satoshi Takeya ◽  
Akihiro Hachikubo
Keyword(s):  
Vibrational Frequencies ◽  
Clathrate Hydrates ◽  
Effect Of Temperature ◽  
Guest Molecules

Retraction of ‘Effect of temperature and large guest molecules on the C–H symmetric stretching vibrational frequencies of methane in structure H and I clathrate hydrates’ by Akihiro Hachikubo et al., RSC Adv., 2018, 8, 3237–3242, DOI: 10.1039/c7ra12334e.

scholarly journals Temperature effects on the C–H symmetric stretching vibrational frequencies of guest hydrocarbon molecules in 512, 51262 and 51264 cages of sI and sII clathrate hydrates

RSC Advances ◽  
2020 ◽  
Vol 10 (61) ◽  
pp. 37582-37587
Author(s):  
Go Fuseya ◽  
Satoshi Takeya ◽  
Akihiro Hachikubo
Keyword(s):  
Temperature Effects ◽  
Vibrational Frequencies ◽  
Clathrate Hydrates ◽  
Hydrocarbon Molecules

Temperature effects on the C–H symmetric stretch of hydrocarbons in various cages of sI and sII clathrate hydrates were observed.

scholarly journals Characterization of free radicals in clathrate hydrates of pyrrole, thiophene, and isoxazole by muon spin spectroscopy

2018 ◽  
Vol 96 (2) ◽  
pp. 217-225 ◽  
Author(s):  
Mina Mozafari ◽  
Lalangi Chandrasena ◽  
Iain McKenzie ◽  
Kerim Samedov ◽  
Paul W. Percival
Keyword(s):  
Free Radicals ◽  
Muon Spin ◽  
Carbon Dioxide Sequestration ◽  
Clathrate Hydrates ◽  
Pure Liquid ◽  
Guest Molecules ◽  
Hyperfine Constants ◽  
Potential Applications ◽  
Muon Spin Spectroscopy

Gas hydrates have long been of interest to the petrochemical industry, but there has been growing interest in potential applications for carbon dioxide sequestration and hydrogen storage. This has prompted many fundamental studies of structure and host–guest interactions, but there has been relatively little investigation of chemical reactions of the guest molecules. In previous work, we have shown that it is possible to use muon spin spectroscopy to characterize H atom like muonium and muoniated free radicals formed in clathrate hydrates. Muonium (Mu) forms in clathrate hydrates of cyclopentane and tetrahydrofuran, whereas furan and its dihydro derivatives form radicals. The current work extends studies to clathrates hydrates of other five-membered heterocycles: thiophene, pyrrole, and isoxazole. All form structure II hydrates. In addition to the clathrates, pure liquid samples of the heterocycles were studied to aid in the assignment of radical signals and for comparison with the enclathrated radicals. Similar to furan, two distinct radicals are formed when Mu reacts with thiophene and pyrrole. However, only one muoniated radical was detected from isoxazole. Muon, proton, and nitrogen hyperfine constants were determined and compared with values predicted by DFT calculations to aid the structure assignments. The results show that Mu adds preferentially to the carbon adjacent to the heteroatom in thiophene and pyrrole and to the carbon adjacent to oxygen in isoxazole. The same radicals are formed in clathrates, but the spectra have broader signals, suggesting slower tumbling. Furthermore, additional signals in the avoided level-crossing spectra indicate anisotropy consistent with restricted motion of the radicals in the clathrate cages.

scholarly journals Effect of Temperature on Stiffness of Sandstones from the Deep North Sea Basin

2020 ◽  
Author(s):  
Tobias Orlander ◽  
Katrine Alling Andreassen ◽  
Ida Lykke Fabricius
Keyword(s):  
North Sea ◽  
Temperature Effects ◽  
Mass Density ◽  
Thermal Strain ◽  
High Stress ◽  
Testing Temperature ◽  
Effect Of Temperature ◽  
Stress Regime ◽  
The North

Abstract Development of high-pressure, high-temperature (HPHT) petroleum reservoirs situated at depths exceeding 5 km and in situ temperature of 170 °C increases the demand for theories and supporting experimental data capable of describing temperature effects on rock stiffness. With the intention of experimentally investigating temperature effects on stiffness properties, we investigated three sandstones from the deep North Sea Basin. As the North Sea Basin is presently undergoing substantial subsidence, we assumed that studied reservoir sandstones have never experienced higher temperature than in situ. We measured ultrasonic velocities in a low- and high-stress regime, and used mass density and stress–strain curves to derive, respectively, dynamic and static elastic moduli. We found that in both regimes, the dry sandstones stiffens with increasing testing temperature and assign expansion of minerals as a controlling mechanism. In the low-stress regime with only partial microcrack closure, we propose closure of microcracks as the stiffening mechanism. In the high-stress regime, we propose that thermal expansion of constituting minerals increases stress in grain contacts when the applied stress is high enough for conversion of thermal strain to thermal stress, thus leading to higher stiffness at in situ temperature. We then applied an extension of Biot’s effective stress equation including a non-isothermal term from thermoelastic theory and explain test results by adding boundary conditions to the equations.

Effect of temperature on atrial and ventricular adenosine A1 receptors of the guinea pig

1986 ◽  
Vol 64 (12) ◽  
pp. 1497-1502 ◽  
Author(s):  
Edward Leung ◽  
Elizabeth A. Woodcock
Keyword(s):  
Adenylate Cyclase ◽  
Guinea Pig ◽  
Adenosine Receptors ◽  
Temperature Effects ◽  
Effect Of Temperature ◽  
Maximal Inhibition ◽  
Guinea Pig Heart ◽  
Adenylate Cyclase Inhibition ◽  
Adenosine A1 ◽  
Two Temperatures

Cardiac adenosine receptors are coupled to adenylate cyclase inhibition. In the guinea pig heart, the relative agonist potencies observed for adenylate cyclase inhibition were R-N6-phenylisopropyladenosine (R-PIA) = N6-cyclohexyladenosine > 5′-N-ethylcarboxamidoadenosine [Formula: see text]S-PIA. In both atrial and ventricular membranes, the antagonists 8-phenyltheophylline (8-PT) and isobutylmethylxanthine (IBMX) also showed similar affinities for atrial and ventricular adenosine receptors. The same pattern of relative agonist potencies was observed in experiments performed at either 25 or 37 °C. However, the maximal inhibition produced by R-PIA in atrial membranes decreased from 30.8 ± 3.2% (n = 7) at 25 °C to 18.8 ± 1.6% (n = 4) at 37 °C. No such difference in maximal inhibition was observed with ventricular membranes at these two temperatures (34.5 ± 1.6%, n = 6 at 25 °C and 35.3 ± 0.9%, n = 11 at37 °C). While there was no change in agonist potencies, the affinities of the antagonists 8-PT and IBMX at cardiac adenosine A1 receptors were affected by temperature. At 25 °C, the pKD values for 8-PT and IBMX in ventricular membranes were 4.65 ± 0.21 (n = 3) and 4.55 ± 0.20 (n = 3), respectively. Their affinities were 7-to 19-fold higher at 37 °C, the pKD values being 5.93 ± 0.12 (n = 7) (p < 0.02) and 5.38 ± 0.18 (n = 3) (p < 0.05), respectively. Over the same temperature range, the affinity of the muscarinic antagonist atropine was increased only by two-fold. These results suggest that (i) atrial and ventricular adenosine receptors are similar, (ii) atrial and ventricular adenylate cyclases are different in terms of temperature effects, and (iii) antagonist affinities at cardiac A1 receptors are critically dependent on temperature.

Polarization response of clathrate hydrates capsulated with guest molecules

2016 ◽  
Vol 144 (20) ◽  
pp. 204308 ◽  
Author(s):  
Qun Zeng ◽  
Jinshan Li ◽  
Hui Huang ◽  
Xinqin Wang ◽  
Mingli Yang
Keyword(s):  
Clathrate Hydrates ◽  
Guest Molecules ◽  
Polarization Response
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