Выделение меченых соединений методом препаративной хроматографии

Mica Track Microfilters (MTM) are successful applied to separate two different and strongly mixed liquid phases (emulsion). The organic and the inorganic phase of the emulsion were 30% tributyl phosphate (TBP) in kerosene and 2 N HNO₃ (or H₂O), respectively. Mica filters with sharp edges (i.e. etched with H₂F₂) and having pore sizes k of 8 μm > k > 2 μm are used to get under some well defined conditions a rather complete extraction of the aqueous phase out of the emulsion. The system was calibrated with the pure phases (water as well as TBP in kerosene), and the liquid throughput is shown as a function of the pore size of the filter. The throughput depends mainly on the pore size and not that much on the kind of liquid, it is slightly larger for water as compared to that of TBP in kerosene.     

Das 15N-Programm des Instituts für stabile Isotope

Design and performance of a radiometric device for the determination of the phase boundary between two nonmiscible liquids are described. The device is based on the principle of simple radioactive relays, but provides maximum information by the connection of limit switch signals.     

Über die Organisation der Produktion von Isotopen,Kernstrahlungsquellen, Radioisotopengeräten für die technologische Kontrolle und Anlagen für die Strahlentechnik in der UdSSR sowie über die Organisation ihrer Einführung in die Volkswirtschaft

Es werden flogende Fragen zur Produktion von Isotopen, Kernstrahlungsquellen und Radioisotopengeräten in der UdSSR behandelt: das Sortiment in der Isotopenproduktion und der Isotopentechnik; die Planung und Spezialisierung der industriellen Fertigung von Isotopenerzeugnissen und isotopentechnischen Gerāten; volkswirtschaftliche Überlegungen dazu; Anwendung und Ausbildung für die Anwendung der Atomenergie.     

Simple Synthesis of Stable Phosphorus Ylides Derived from Imidazolidine-2-Thione. Efficient One-Pot Synthesis of α-Amino Esters with β-Phosphorus Substituents

Crystalline phosphorus ylides are obtained in nearly quantitative yields from the addition reaction between triphenylphosphine, dialkyl acetylenedicarboxylates, and imidazolidine-2-thione. A dynamic NMR effect is observed in the ¹ H NMR spectrum of the stabilized ylide obtained from dimethyl acetylenedicarboxylate (Δ G ^≠ = 66.6 kJmol^?1 ) and is attributed to restricted rotation around the carbon–carbon partial double bond resulting from the conjugation of the ylide moiety with the adjacent carbonyl group.     

SZOLD: Its Properties and Relationship to Other Distributions

SZOLD is a form of the three-parameter lognormal distribution. As originally defined, its normalization factor permits negative values of the distributed variable for some positively skewed distributions and for all negatively skewed distributions. Correct normalization factors are given here, and the degree of truncation is shown as a function of the distribution parameters.     

Synthesis of stable oxazolidine nitroxyl radicals with methoxy groups at the α-carbon atoms to the radical site

The condensation of -hydroxyaminoalcohols with aldehydes and acetone gave 3-hydroxyoxazolidines and tautomeric N-(2-hydroxyethyl)--arylnitrones, whose oxidation by PbO₂ in methanol leads to stable oxazolidine nitroxyl radicals with methoxy groups at C² and C⁴.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk 630090. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 4, pp. 966–973, April, 1992.     

温度与碱浓度对FeO4^2-/FeO2^-体系电化学行为的影响

研究了影响Fe（OH）3进行酸式电离反应的因素，在多种浓度和温度条件下的NaOH浓溶液中采用SnO2-Sb2O3／Ti电极，研究FeO4^2-/FeO2^-体系的电化学氧化还原反应参数及其变化趋势，结果证实该体系发生电化学氧化还原反应的最佳碱溶液浓度范围为12—14mol／L，最佳温度范围为295～315K．阐明了在实验条件下FeO4^2-/FeO2^-氧化还原体系中存在由FeO4^2-/FeO2^-构成的氧化还原电对，而FeO2不直接与FeO2构成氧化还原电对；并给出了FeO4^2-/FeO2^-氧化还原体系的Latimer图．     

温度与碱浓度对FeO_4~(2-)/FeO_2~-体系电化学行为的影响

研究了影响Fe(OH)3进行酸式电离反应的因素,在多种浓度和温度条件下的NaOH浓溶液中采用SnO2-Sb2O3/Ti电极,研究FeO42-/FeO2-体系的电化学氧化还原反应参数及其变化趋势,结果证实该体系发生电化学氧化还原反应的最佳碱溶液浓度范围为12~14 mol/L,最佳温度范围为295~315 K.阐明了在实验条件下FeO42-/FeO2-氧化还原体系中存在由FeO43-/FeO2-构成的氧化还原电对,而FeO42-不直接与FeO2-构成氧化还原电对;并给出了FeO42-/FeO2-氧化还原体系的Latim er图.     

Synthesis of a Stable N‐Hetero‐RhI‐Metallacyclic Silanone

A novel N‐hetero‐Rh^I‐metallacyclic silanone 2 has been synthesized. The silanone 2 , showing an extremely large dimerization energy (ΔG=+86.2 kcal mol^?1), displays considerable stability and persists in solution up to 60 °C. Above 120 °C, an intramolecular C_sp3?H insertion occurs slowly over a period of two weeks leading to the bicyclic silanol 5 . The exceptional stability of 2 , related to the unusual electronic and steric effects of Rh^I‐substituent, should allow for a more profound study and understanding of these new species. Furthermore, the metallacyclic silanone 2 presents two reactive centers (Si=O and Rh), which can be involved depending upon the nature of reagents. Of particular interest, the reaction with H₂ starts with the hydrogenation of Rh^I center leading to the corresponding Rh^III‐dihydride complex 7 and it undergoes a cis/trans‐isomerization via a particular mechanism, demonstrating that addition‐elimination processes can also happen for silanones just like for their carbon analogues!     

Fragmentation pathways of protonated coumarin by ESI‐QE‐Orbitrap‐MS/MS coupled with DFT calculations

Coumarin is one of the basic structures of naturally oxygen heterocyclic compound, which was investigated in this paper for its gas‐phase fragmentation behaviors using electrospray quadrupole extractive orbitrap mass spectrometry in the positive mode. The possible fragmentation pathways were proposed based on electrospray ionization (ESI)‐ mass spectrometry (MS)/MS data and theory calculation. The elimination of two CO and CO₂ was observed for protonated coumarin, which was followed by the formation of a stabilized seven‐, six‐, and five‐membered ring carbocation by loss of C2H2. The possible protonation sites occurred at Oxygen 11 atom of coumarin were the main fragmentation pathways. The relative abundance of characteristic fragment ions and the energy‐resolved breakdown curves were used to confirm the cleavage mechanism of protonated coumarin. The methodology and results of present work would contribute to the chemical structure identification of other coumarins.