Photolyse de l'isoprène gazeux entre son seuil d'absorption (ca. 255 nm) et 147.0 nm

1978 ◽  
Vol 56 (14) ◽  
pp. 1864-1870 ◽  
Author(s):  
Rosaire Demers ◽  
Guy J. Collin ◽  
H. Gagnon-Deslauriers
Keyword(s):  
High Pressure ◽  
Pressure Dependence ◽  
Lower Energy ◽  
Main Product ◽  
Pressure Effect

We studied the photolysis of isoprene at wavelengths between the absorption threshold (ca. 255 nm) and 147.0 nm. The pressure effect was studied between 30 and 2660 N m−2. At the lower energy, light products are formed and their yields decrease with an increase in the pressure. From Stern–Volmer plots, we have concluded that the photoexcited molecule is collision stabilized at high pressure. Less pressure dependence was observed at 174 and at 163.3 nm. At these energies, and at 147 nm, all of the photoexcited molecules decompose. At 147 nm, no pressure effect was observed, and the main product is vinylacetylene (Ф = 0.66). The formation of this product was explained on the basis of the CH3—C4H5 split followed by the fragmentation of the excited C4H5* radicals. At 174 nm, this last radical is collisionally stabilized. Finally we have measured the ratio k(CH3 + H2S)/k(CH3 + isoprene) = k1/k12 and k1/k12 = 41 + 3

Measured temperature and pressure dependence of Vp and Vs in compacted, polycrystalline sI methane and sII methane–ethane hydrate

2003 ◽  
Vol 81 (1-2) ◽  
pp. 47-53 ◽  
Author(s):  
M B Helgerud ◽  
W F Waite ◽  
S H Kirby ◽  
A Nur
Keyword(s):  
High Pressure ◽  
Shear Wave ◽  
Pressure Dependence ◽  
Gas Hydrate ◽  
Pressure Vessel ◽  
Wave Speed ◽  
Measured Temperature ◽  
Shear Wave Speed ◽  
Temperature And Pressure ◽  
Fixed End

We report on compressional- and shear-wave-speed measurements made on compacted polycrystalline sI methane and sII methane–ethane hydrate. The gas hydrate samples are synthesized directly in the measurement apparatus by warming granulated ice to 17°C in the presence of a clathrate-forming gas at high pressure (methane for sI, 90.2% methane, 9.8% ethane for sII). Porosity is eliminated after hydrate synthesis by compacting the sample in the synthesis pressure vessel between a hydraulic ram and a fixed end-plug, both containing shear-wave transducers. Wave-speed measurements are made between –20 and 15°C and 0 to 105 MPa applied piston pressure. PACS No.: 61.60Lj

High-pressure effect on inverse spinel LiCuVO4: X-ray diffraction and Raman scattering

2013 ◽  
Vol 22 (1) ◽  
pp. 016103 ◽  
Author(s):  
Heng-Nan Liang ◽  
Chun-Li Ma ◽  
Fei Du ◽  
Qi-Liang Cui ◽  
Guang-Tian Zou
Keyword(s):  
High Pressure ◽  
Raman Scattering ◽  
Pressure Effect ◽  
X Ray Diffraction ◽  
Inverse Spinel ◽  
X Ray ◽  
High Pressure Effect

scholarly journals High pressure effect on bonding nature in KMnF3

2005 ◽  
Vol 61 (a1) ◽  
pp. c464-c465
Author(s):  
S. Aoyagi ◽  
S. Toda ◽  
E. Nishibori ◽  
Y. Kuroiwa ◽  
T. Adachi ◽  
...  
Keyword(s):  
High Pressure ◽  
Pressure Effect ◽  
High Pressure Effect

Intermolecular Interactions of Xe Atoms Confined in One-dimensional Nanochannels of Tris(o-phenylenedioxy)cyclotriphosphazene as Studied by High-pressure 129Xe NMR

2003 ◽  
Vol 58 (12) ◽  
pp. 727-734 ◽  
Author(s):  
Hirokazu Kobayashi ◽  
Takahiro Ueda ◽  
Keisuke Miyakubo ◽  
Taro Eguchi
Keyword(s):  
High Pressure ◽  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Pressure Dependence ◽  
Average Distance ◽  
Chemical Shift Tensor ◽  
Axially Symmetric ◽  
One Dimensional ◽  
129Xe Nmr ◽  
The One

The pressure dependence of the 129Xe chemical shift tensor confined in the Tris(o-phenylenedioxy) cyclotriphosphazene (TPP) nanochannel was investigated by high-pressure 129Xe NMR spectroscopy. The observed 129Xe spectrum in the one-dimensional TPP nanochannel (0.45 nm in diameter) exhibits a powder pattern broadened by an axially symmetric chemical shift tensor. As the pressure increases from 0.02 to 7.0 MPa, a deshielding of 90 ppm is observed for the perpendicularcomponent of the chemical shift tensor δ⊥, whereas a deshielding of about 30 ppm is observed for the parallel one, δ‖. This suggests that the components of the chemical shift tensor, δ‖ and δ⊥, are mainly dominated by the Xe-wall and Xe-Xe interaction, respectively. Furthermore, the effect of helium, which is present along with xenon gas, on the 129Xe chemical shift is examined in detail. The average distance between the Xe atoms in the nanochannel is estimated to be 0.54 nm. This was found by using δ⊥ at the saturated pressure of xenon, and comparing the increment of the chemicalshift value in δ⊥ to that of a β -phenol/Xe compound.

scholarly journals Salt Distribution and Salt Uptake during Ripening in Turkish White Cheese Affected by High Pressure Processing

2018 ◽  
Vol 6 (4) ◽  
pp. 433
Author(s):  
Nurcan Koca ◽  
Raghu Ramaswamy ◽  
W.M. Balasubramaniam ◽  
W. James Harper
Keyword(s):  
High Pressure ◽  
Pressure Effect ◽  
High Pressure Processing ◽  
Holding Time ◽  
Salt Uptake ◽  
White Cheese ◽  
Textural Changes ◽  
Salt Distribution ◽  
High Pressure Effect

Turkish white cheeses after brine salting were subjected to high pressure processing (HPP) at 50, 100, 200 and 400 MPa for 5 and 15 min and the samples pressurized for 15 min were ripened in brine for 60 days. The effects of HPP on the salt distribution in external, middle and internal zones of cheese after pressurization and on the salt uptake of whole cheese block during ripening were investigated. HPP did not change the values of moisture, salt and salt in moisture in different zones of cheese. Furthermore, pressure holding time had no effect on salt distribution in cheese. The salt contents of un-pressurized and pressurized cheese samples were equilibrated on the 14th day of ripening, and then stabilized, with no high pressure effect. As a result, HPP at pressures up to 400 MPa did not significantly affect neither salt distribution after high pressure processing nor salt uptake during ripening. However, a slight increase in moisture at the pressures of 200-400 MPa on the 60th day of ripening, which was not significant, might warn further increases in moisture of white cheese for longer ripening periods than 60 days. Higher pressure applications may alter all those values in white cheese because of textural changes.

scholarly journals High-pressure effect on the superconductivity ofYB6

2014 ◽  
Vol 90 (4) ◽  
Author(s):  
S. Gabáni ◽  
I. Takáčová ◽  
G. Pristáš ◽  
E. Gažo ◽  
K. Flachbart ◽  
...  
Keyword(s):  
High Pressure ◽  
Pressure Effect ◽  
High Pressure Effect
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