Decarboxylation of Carnitine and α-Cyano-4-Hydroxycinnamic Acid under Particle Bombardment

2000 ◽  
Vol 6 (2) ◽  
pp. 175-185 ◽  
Author(s):  
Sophie Bourcier ◽  
Yannik Hoppilliard ◽  
Jean Marie Pechiné ◽  
Felix Perez
Keyword(s):  
Particle Bombardment ◽  
High Energy ◽  
Hydroxycinnamic Acid ◽  
Species Loss ◽  
Laser Photon ◽  
Photon Irradiation ◽  
Fragmentation Mechanisms ◽  
High Energy Collisions ◽  
Protonated Molecules

Protonated carnitine and α-cyano-4-hydroxycinnamic acid were formed by laser photon irradiation, by MeV-ion bombardment and by electrospray. The spontaneous fragmentations of protonated molecules formed upon particle bombardment are compared with the decompositions induced by low- and high-energy collisions of molecules protonated by electrospray. The determination of fragmentation mechanisms was achieved using labelled compounds and by means of ab initio calculations. The most prominent fragmentation of protonated molecules formed under particle bombardment is an unexpected loss of carbon dioxide. More classical processes dominate the decomposition induced by collisions of electrosprayed species: loss of trimethylamine and 4-hydroxybutyrolactone from protonated carnitine, loss of water from protonated cinnamic acid but no loss of CO2. Decarboxylation occurring before or concomitant with protonation is proposed to interpret these results.

Do Thermally-Labile 1,4-Benzodiazepines Rearrange under Electrospray and Particle Bombardment?

2001 ◽  
Vol 7 (4-5) ◽  
pp. 359-371 ◽  
Author(s):  
Sophie Bourcier ◽  
Yannik Hoppilliard ◽  
Taraneh Kargar-Grisel ◽  
Jean Marie Pechiné ◽  
Felix Perez
Keyword(s):  
Particle Bombardment ◽  
Bond Cleavage ◽  
High Energy ◽  
Hydroxyl Group ◽  
Molecular Orbital Calculations ◽  
Energy Collision ◽  
Fragmentation Mechanisms ◽  
Uv Photons ◽  
The Stability ◽  
Protonated Molecules

Nordiazepam (N), diazepam (D), lorazepam (L), oxazepam (O)and temazepam (T)are 1,4-benzodiazepines. L, O and T are substituted in position 3 of the seven-membered ring by a hydroxyl group and are known to be thermally unstable. N and D are unsubstituted in position 3 and are expected to be thermally stable. We have studied the stability of all these molecules under electrospray conditions and under particle bombardment (MeV ions and UV photons). The fragmentations induced by low energy collision-induced dissociation and high energy collision-activated dissociation of molecules protonated by electrospray were compared with the spontaneous fragmentations of these molecules ionized by particle bombardment. The fragmentation mechanisms were determined using labeled compounds and by means of ab initio calculations using 1,4-diazepine and 3-hydroxy-1,4-diazepine as models. The fragmentation is dramatically dependent upon the substitution in position 3 and upon the internal energy of protonated molecules. At low collision energies, the non-hydroxylated benzodiazepines eliminate CO by opening of the diazepine ring whereas 3-hydroxy-1,4-benzodiazepines eliminate water after ring contraction. At high collision energies, all protonated benzodiazepines eliminate a hydrogen atom by simple bond cleavage. Molecular orbital calculations give arguments in favor of an isomerization in the gas phase of the protonated 3-hydroxybenzodiazepines and of a partial thermal decomposition of 1,4-benzodiazepines occurring before protonation under particle bombardment.

Kinematic Approximations in TED and RHEED Analysis of Reconstructed Surfaces

1990 ◽  
Vol 48 (2) ◽  
pp. 396-397
Author(s):  
L. -M. Peng ◽  
M. J. Whelan
Keyword(s):  
Electron Diffraction ◽  
Kinematic Analysis ◽  
Incident Beam ◽  
High Energy ◽  
Energy Electron ◽  
Great Success ◽  
High Energy Electron ◽  
Kinematic Approximation ◽  
Reconstructed Surfaces

In recent years there has been a trend in the structure determination of reconstructed surfaces to use high energy electron diffraction techniques, and to employ a kinematic approximation in analyzing the intensities of surface superlattice reflections. Experimentally this is motivated by the great success of the determination of the dimer adatom stacking fault (DAS) structure of the Si(111) 7 × 7 reconstructed surface.While in the case of transmission electron diffraction (TED) the validity of the kinematic approximation has been examined by using multislice calculations for Si and certain incident beam directions, far less has been done in the reflection high energy electron diffraction (RHEED) case. In this paper we aim to provide a thorough Bloch wave analysis of the various diffraction processes involved, and to set criteria on the validity for the kinematic analysis of the intensities of the surface superlattice reflections.The validity of the kinematic analysis, being common to both the TED and RHEED case, relies primarily on two underlying observations, namely (l)the surface superlattice scattering in the selvedge is kinematically dominating, and (2)the superlattice diffracted beams are uncoupled from the fundamental diffracted beams within the bulk.

scholarly journals Thermal Dynamic Behavior in Bi-Zone Habitable Cell with and without Phase Change Materials

Proceedings ◽  
2020 ◽  
Vol 63 (1) ◽  
pp. 41
Author(s):  
Hanae El Fakiri ◽  
Lahoucine Ouhsaine ◽  
Abdelmajid El Bouardi
Keyword(s):  
Thermal Behavior ◽  
Thermal Comfort ◽  
Phase Change ◽  
Dynamic Behavior ◽  
Phase Change Materials ◽  
Energy Performance ◽  
High Energy ◽  
Water Heater ◽  
Simplified Modeling

The thermal dynamic behavior of buildings represents an important aspect of the energy efficiency and thermal comfort of the indoor environment. For this, phase change material (PCM) wallboards integrated into building envelopes play an important role in stabilizing the temperature of the human comfort condition. This article provides an assessment of the thermal behavior of a “bi-zone” building cell, which was built based on high-energy performance (HEP) standards and heated by a solar water heater system through a hydronic circuit. The current study is based on studying the dynamic thermal behavior, with and without implantation of PCMs on envelope structure, using a simplified modeling approach. The evolution of the average air temperature was first evaluated as a major indicator of thermal comfort. Then, an evaluation of the thermal behavior’s dynamic profile was carried out in this study, which allowed for the determination of the PCM rate anticipation in the thermal comfort of the building cell.

scholarly journals Strangeness Suppression and Color Deconfinement

2018 ◽  
Vol 171 ◽  
pp. 02005
Author(s):  
Helmut Satz
Keyword(s):  
Initial Temperature ◽  
Strange Particle ◽  
High Energy ◽  
Universal Function ◽  
Ideal Gas ◽  
Entropy Density ◽  
Suppression Factor ◽  
Thermal Medium ◽  
High Energy Collisions ◽  
Hadronic Resonances

The relative multiplicities for hadron production in different high energy collisions are in general well described by an ideal gas of all hadronic resonances, except that under certain conditions, strange particle rates are systematically reduced. We show that the suppression factor γs, accounting for reduced strange particle rates in pp, pA and AA collisions at different collision energies, becomes a universal function when expressed in terms of the initial entropy density s0 or the initial temperature T of the produced thermal medium. It is found that γs increases from about 0.5 to 1.0 in a narrow temperature range around the quark-hadron transition temperature Tc ≃ 160 MeV. Strangeness suppression thus disappears with the onset of color deconfinement; subsequently, full equilibrium resonance gas behavior is attained.

X‐ray determination of the Debye temperature at high pressure using high‐energy synchrotron radiation

1990 ◽  
Vol 68 (6) ◽  
pp. 2719-2722 ◽  
Author(s):  
A. Matsumuro ◽  
M. Kobayashi ◽  
T. Kikegawa ◽  
M. Senoo
Keyword(s):  
High Pressure ◽  
Synchrotron Radiation ◽  
Debye Temperature ◽  
High Energy ◽  
X Ray

scholarly journals Absolute cross sections for the dissociation of hydrogen cluster ions in high-energy collisions with helium atoms

2006 ◽  
Vol 73 (2) ◽  
Author(s):  
S. Eden ◽  
J. Tabet ◽  
K. Samraoui ◽  
S. Louc ◽  
B. Farizon ◽  
...  
Keyword(s):  
Cross Sections ◽  
High Energy ◽  
Cluster Ions ◽  
Helium Atoms ◽  
High Energy Collisions
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