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101.
A radiometric method for the determination of cadmium based on two-phase isotope exchange has been developed. The sample containing cadmium is shaken in the presence of tartrate with a standard cadmium-115m diethyldithiocarbamate solution in chloroform. From the distribution of the activity between the aqueous and organic phases 0.05–7 g of cadmium in 5–20 ml sample can be determined.Dedicated to Prof. V. D. Nefedov on the occasion of his 70th birthday 相似文献
102.
The fragmentation of the homologous fatty acid tetraesters of pentaerythritol (C-2 to C-14) upon electron impact was investigated. The main fragment ions are [M? RCOO]+ and [M? RCOOH]+, for which cyclic acetal structures are postulated. Subsequent fragmentation was elucidated by ‘direct analysis of daughter ion’ (DADI) measurements and high resolution measurements. Esters of branched fatty acids can be distinguished from esters of n-fatty acids by characteristic ions. Isomeric esters of n-fatty acids cannot be separated by gas chromatography but identification is also possible by mass spectrometry. 相似文献
103.
A. Zeman 《Journal of Radioanalytical and Nuclear Chemistry》1996,208(1):229-242
The solvent extraction of europium(III) with di-n-butylphosphoric {HDBP} and di-(2-ethylhexyl)phosphoric {HDEHP} acids in 3-methyl-1-butanol from 0.1 and 1.0M perchlorate medium {Na(H)ClO4} was studied at pH 1–3. It was found that the composition of the species extracted into the organic phase depended on the concentration of perchlorate anion. In 0.1M Na(H)ClO4 solutions, simple chelates Eu(DBP)3 or Eu(DEHP)3 are extracted while mixed ligand complexes Eu(DBP)2ClO4 or Eu(DEHP)2ClO4 are also extracted from 1.0M Na(H)ClO4 solutions. Compared to the extractions from perchlorate solutions, no such change in the extraction mechanism has been observed in chloride solutions containing up to 1.0M Cl–. The extraction of europium(III) with these extractants into toluene from 0.1M perchlorate or chloride media was studied as well. The extraction species found were identical with those reported in the literature, i.e. {Eu[H(DBP)2]3, Eu[H(DEHP)2]3}. The extraction equilibrium constants were calculated for all complexes. 相似文献
104.
Differential scanning calorimetry was used to determine the heats of decomposition of 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane(HMX), 1,5-diacetyl-3,7-dinitro-1,3, 5,7-tetraazacyclooctane(DADN), 1,5-endomethylene-3,7-dinitro-1,3,5,7-tetraazacyclooctane(DPT), 1,3,5-trinitro-1,3,5-triazacyclohexane(RDX), 1,3,5-trinitroso-1,3,5-triazacyclohexane (R-salt), and 1,5-endomethylene-3,7-dinitroso-1,3,5,7-tetraazacyclooctane(DNPT). The value of the decomposition heat of unit mass of sample was found to increase inHMX, DADN andRDX with decreasing degree of filling of the reaction volume. In the R-salt and inDNPT, however, the trend of this dependence was found to be the reverse and more pronounced. No analogous dependence was found to exist forDPT under the given experimental conditions.
The authors express their gratitude to Mr. Milan Andoga for his precise DSC measurements. 相似文献
Zusammenfassung Die Bestimmung der Zersetzungswärmen von 1,3,5,7-Tetranitro-1,3,5,7-tetraazacyclooktan(HMX), 1,5-Diacetyl-3,7-dinitro-1,3,5,7-tetraazacyclooktan(DADN), 1,5-Endomethylen-3,7-dinitro-1,3,5,7-tetraazacyclooktan (DPT), 1,3,5-Trinitro-1,3,5-triazacyclohexan(RDX), 1,3,5-Trinitroso-1,3,5-triazacyclohexan (R-salz) und 1,5-Endomethylen-3,7-dinitroso-1,3,5,7-tetraazacyclooktan(DNPT) wurde mittels Differential-Abtastkalorimetrie durchgeführt. Es wurde festgestellt, daß der Wert der Zersetzungswärme der Masseneinheit der Probe beiHMX, DADN undRDX mit abnehmendem Füllungsgrad des Reaktionsvolumens zunimmt. Bei R-salz undDNPT war hingegen die Richtung der Abhängigkeit umgekehrt und stärker. Keine analoge Abhängigkeit wurde fürDPT unter den Bedingungen des obigen Versuchs gefunden.
Résumé On a déterminé par analyse calorimétrique différentielle les chaleurs de décomposition des composés suivants: 1,3,5,7-tétranitro-1,3,5,7-tétraazacyclooctane (HMX), 1,5-diacé tyle-3,7-dinitro-1,3,5,7-tétraazacyclooctane(DADN), 1,5-endométhylène-3,7-dinitro-1,3,5,7-tétraazacyclooctane(DPT), 1,3,5-trinitro-1,3,5-triazacyclohexane(RDX), 1,3,5-trinitroso-1,3,5-triazacyclohexane (selR) et 1,5-endométhylène-3,7-dinitroso-1,3,5,7-tétraazacyclooctane(DNPT). La valeur de la chaleur de décomposition par masse unité d'échantillon augmente dans le cas deHMX, DADN etRDX, quand le degré de remplissement du volume réactionnel diminue. On a trouvé, cependant, avec le selR et leDNPT, une dépendance inverse et plus prononcée. Aucune dépendance similaire n'a été trouvée, dans les conditions expérimentales appliquées dans le cas duDPT.
-5- . . , , .
The authors express their gratitude to Mr. Milan Andoga for his precise DSC measurements. 相似文献
105.
Andrés Eduardo Caicedo Paul Larson Grigor Sargsyan Ralf Schindler John Steel Martin Zeman 《Israel Journal of Mathematics》2017,217(1):231-261
By forcing with Pmax over strong models of determinacy, we obtain models where different square principles at ω 2 and ω 3 fail. In particular, we obtain a model of \({2^{{\aleph _0}}} = {2^{{\aleph _1}}} = {\aleph _2} + {\neg }\square \left( {{\omega _2}} \right) + {\neg }\square \left( {{\omega _3}} \right)\). 相似文献
106.
The paper deals with modelling of vibration of shaft systems with gears and rolling-element bearings using the modal synthesis method with DOF number reduction. The influence of the nonlinear bearing and gearing contact forces with the possibility of the contact interruption is respected. The gear drive nonlinear vibrations caused by internal excitation generated in gear meshing, accompanied by impact and chaotic motions are studied. The theory is applied to a simple test-gearbox. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
107.
Kaizer Jakub Ješkovský Miroslav Kvasniak Jakub Zeman Jakub Pánik Ján Povinec Pavel P. 《Journal of Radioanalytical and Nuclear Chemistry》2022,331(3):1249-1259
Journal of Radioanalytical and Nuclear Chemistry - Nutrition and safety of foods is one of the more discussed topics in the modern society. We processed twenty food samples of the organic and... 相似文献
108.
109.
Dong Jun Yan Qi-Long Liu Pei-Jin He Wei Qi Xiao-Fei Zeman Svatopluk 《Journal of Thermal Analysis and Calorimetry》2018,131(2):1391-1403
Journal of Thermal Analysis and Calorimetry - In this paper, the thermal stability and decomposition kinetics of 10 nitric esters including nitroglycerine (NG), pentaerythritol tetranitrate (PETN),... 相似文献
110.