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T. Martinez M. Navarrete L. Cabrera F. Juárez A. Ramos K. Vazquez 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(3):569-572
Nine brands of tobacco cigarettes manufactured and distributed in the Mexican market were analyzed by γ-spectrometry to certify
their non-artificial radioactive contamination. Since natural occurring radioactive materials (NORM) 40K, 232Th, 235U, and 239U (and decay products from the latter three nuclides) are the main sources for human radiation exposure, the aim of this work
was to determine the activity of 40K and potassium concentration. Averages of 40K and potassium concentration were of 1.29±0.18 Bq·g−1, and 4.0±0.57%. The annual dose equivalents to the whole body from ingestion and inhalation of 26 Bq 40K were 0.23 μSv and 15.8 μSv, respectively. The corresponding 50 years committed dose equivalents was 0.23 μSv. The total
committed dose to the lungs due to inhalation of 40K in tobacco was 16 μSv. Potassium concentrations obtained in this work were in the same range of those obtained by INAA,
so showing that the used technique is acute, reproducible, and accessible to laboratories equipped with low background scintillation
detectors. 相似文献
4.
Muhammad Faisal Nobuaki Sato Armando T. Quitain Hiroyuki Daimon Koichi Fujie 《国际化学动力学杂志》2007,39(3):175-180
The kinetics and pathway of hydrothermal decomposition of aspartic acid were studied using a continuous‐flow tubular reactor. The reaction was carried out in the temperature range of 200–260°C and at a pressure of 20 MPa. Deamination was the primary reaction, indicated by the presence of significant amount of ammonia, fumaric acid, or maleic acid in the products. Other reaction products were pyruvic acid, malic acid, and traces of succinic and lactic acid. Traces of alanine were also detected, showing the possibility of decomposing high‐molecular weight amino acids to obtain simple amino acids such as glycine or alanine. Results on the effect of reaction parameters demonstrated that decomposition of aspartic acid is highly temperature dependent under hydrothermal conditions. For a slight temperature difference of 60°C (from 200 to 260°C), the first‐order reaction rate constants of 0.003 significantly increased to 0.231 s?1. The activation energy was 144 kJ/mol, as calculated by the Arrhenius equation. No significant effect was exhibited by other reaction parameters such as pH and pressure. The results are useful in controlling the hydrolysis of proteinaceous materials toward high yield of aspartic acid under hydrothermal conditions. © 2007 Wiley Periodicals, Inc. 39: 175–180, 2007 相似文献
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Dimitri Markushevich Vladimir B. Matveev Armando Treibich 《Letters in Mathematical Physics》2006,76(2-3):109-109
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Dore Augusto Clemente Armando Marzotto Giovanni Valle 《Journal of chemical crystallography》1988,18(2):147-156
The crystal and molecular structure of thiamine monochloride (C12H17N4OSCl) was determined by X-ray diffraction and refined to a finalR value of 0.042. The compound crystallizes in the monoclinic system, space groupP21/a, with cell constantsa=18.929(4),b=11.663(2),c=6.376(2) Å and=96.72(8)°. The thiamine molecule is anhydrous and unprotonated, and the torsion angles at the methylene carbon show that it possesses anF conformation. The dihedral angle value of 84.16(6)° between thiazolium and pyrimidine rings is in the normal range found for the thiamine withF conformation, protonated or not, hydrated or not. Thiamine therefore has the same conformation notwithstanding protonation or hydration, with the rings similarly oriented in all the crystal structures containing thiamine. 相似文献
7.
R. Cabrera‐Trujillo J. R. Sabin Y.
hrn E. Deumens 《International journal of quantum chemistry》2003,94(4):215-221
Under certain collision conditions, a swift ion projectile colliding with a target will gain rather than lose kinetic energy, contrary to the standard conception of stopping power. In this work, we consider the conditions for such a collision such that the energy loss is negative, that is, that there will be projectile kinetic energy gain. In particular, for a target initially in the ground state we find that the projectile gains kinetic energy only when charge exchange and de‐excitation processes are involved. This occurs when the electron affinity of the projectile is larger than the ionization potential of the target. Consequences of this effect are analyzed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 215–221, 2003 相似文献
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Armando J. L. Pombeiro Raymond L. Richards 《Monatshefte für Chemie / Chemical Monthly》1992,123(8-9):749-756
Summary Reactions oftrans-[M(N2)2(dppe)2] (A;M=Mo, W;dppe=Ph
2PCH2CH2PPh
2) with ethyldiazoacetate, N2CHCOOEt, yield the bisdiazoalkane speciestrans-[M(N2CHCOOEt)2(dppe)2], upon simple replacement of the dinitrogen ligand by ethyldiazoacetate. However, diazomethane, N2CH2, reacts withA with loss of N2 to give products which we tentatively formulate as containing methylene ligands,trans-[M(CH2)2(dppe)2].
Herstellung von Bisdiazoalkan- und ähnlichen Komplexen aus den Reaktionen von Diazoverbindungen mit Distickstoffkomplexen des Typstrans-[M(N2)2(Ph 2PCH2CH2PPh 2)2] mitM=Mo oder W
Zusammenfassung Die Reaktion vontrans-[M(N2)2(dppe)2] (A:dppe=Ph 2PCH2CH2PPh 2 undM=Mo oder W) mit Ethyldiazoacetat, N2CHCOOEt, ergab nach einfachem Austausch des Distickstoffliganden mit Ethyldiazoacetat die Bisdiazoalkanetrans-[M(N2CHCOOEt)2(dppe)2]. Diazomethan (N2CH2) hingegen reagierte mitA unter Verlust von N2 zu Produkten, die tentativ alstrans-[M(CH2)2(dppe)2] mit Methylenliganden formuliert wurden.相似文献