188Os Low Excited Levels

The -ray spectra of ¹⁸⁸Re decay have been studied by using a compton-suppressed spectrometer and a three parameters --T list coincidence system. Six -rays at 557, 810, 1463, 1867, 1936 and 2022 keV and three levels at 1443, 1936 and 2022 keV are confirmed again. Eight new -rays at 309.60±0.04, 826.90±0.02, 979.29±0.08, 1086.13±0.03, 1103.7±0.4, 1828.2±0.1, 1842.5±0.2, 1982.5±0.2 keV have been identified, three new levels at 309.60, 1828.2 and 1982.5 keV are assigned. The ^–-decay branching ratio is deduced.     

Complex formation of unsaturated cyclodextrin solutions with various polymers

By using methyl orange as a competitive complexant, it was shown that solutions of poly(ethylene glycol), poly(propylene glycol) and poly(N-vinylpyrrolidone) equivalent to a concentration of 1.67 mM monomer are able to form soluble inclusion complexes with 0.20 mM solutions of -, - and -cyclodextrins. The complex formation is independent of polymer chain length. Poly(ethylene glycol) solutions complexed, on average with 40%, 45% and 75% of -, -, and -cyclodextrin, respectively. A poly(propylene glycol) solution complexed 55% -cyclodextrin, 80% -cyclodextrin and 90% -cyclodextrin. Poly(N-vinylpyrrolidone) solutions complexed on average with 90% of -, -, and -cyclodextrin.     

A new improved expression for gamma-ray detection efficiency of Ge(Li) detectors

In the present paper, a new improved expression for -ray detection efficiency of Ge(Li) detectors, ⁰ , is given. It is represented as a continuous function of x (viz. E ^–1) with a maximum and decreases very rapidly to a small positive value as -ray energy, E, drops to 40 keV or lower, but slowly as E rises to 1.7 MeV or higher. Since it can well represent the whole physical process of the -ray detection, this expression may be one of the simplest and most precise representations, for ⁰ at the present time.     

Efficiency calibration and summation effects in gamma-ray spectrometry

Precise, absolute -ray efficiences ( ) and total efficiences ( _T), have been measured at various distances from the detector, using a set of standards. The observed linear variation of and _T as well as / _T with E and provides a simple means of interpolation and extrapolation. Experimental coincidence summation effects were determined for various nuclides and compared with calculated values. The results are found to be in good agreement with each other.     

Synthesis of γ- dihydropyrones and β- dihydrofuranones on the basis of acetylenic γ- and δ-keto alcohols and acetals of γ- and δ-formyl alcohols

Acetylenic - and -keto alcohols and acetals of acetylenic - and -keto alcohols and acetals of acetylenic - and -formyl alcohols undergo cyclization to -dihydropyrones and -dihydrofuranones under the influence of acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1471–1473, November, 1976.     

Condensation of 2-(1-ethoxyvinyl)oxiranes with sodiomalonic ester and decarboxylation of the reaction products obtained

-(1-Ethoxyvinyl)- and -(1-ethoxyvinyl)--ethoxycarbonyl--butyrolactones were obtained by the reaction of 2-(1-ethoxyvinyl)oxiranes with sodiomalonic ester. Decarboxylation of the -(1-ethoxyvinyl)--ethoxycarbonyl-butyrolactones in DMSO leads to -(1-ethoxyvinyl)--butyrolactones, the hydrolysis of which gives -acetyl-butyrolactones. Ethyl trans-3-acetyl-3-pentenoate was obtained by decarboxylation of -methyl--(1-ethoxyvinyl)--ethoxycarbonyl--butyrolactone in DMSO.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 22–25, January, 1992.     

Radiation-induced effects on electrical-grade insulating oils

Samples of a new, naphthenic based electrical-grade insulating mineral oil (type AV-58), were irradiated with -rays from a⁶⁰Co source. Doses of up to 640 kGy were used in order to investigate the chemical effects promoted by -rays in the oils. After irradiation the samples were fractionated by preparative liquid chromatography into eight compound classes, which were then analyzed by high resolution gas chromatography. By comparing the profile of each class with the equivalent fractions of the same oil without irradiation, it could be concluded that no appreciable changes were found within the dose range investigated. This result indicates that -ray irradiation of contaminants, such as PCB's, in these oils could be conducted without matrix interference.     

Structure and charge distribution of some alkynoyl cations

We have performedab initio calculations to determine the structure and charge distribution of some alkynoyl cations and their parent alkynoyl fluorides. We have used Mulliken population analysis and a new technique developed by Yáñez, Stewart and Pople. Our results indicate that the mesomeric form O⁺C–CC–R is one of the most important contributors to the structure of these cations, in agreement with experimental conclusions. We have also found that the participation of mesomeric form O=C=C=C⁺ -R is not negligible and increases with -substitution. In the 3-phenylpropynoyl cation substantial delocalization of charge into the phenyl group occurs. Calculations from YSP population analysis are in good agreement with experimental evidence.     

Determination of attenuation coefficient for self-absorption correction in routine gamma ray spectrometry of environmental bulk sample

A simple method to determine -ray attenuation coefficients using Ba-133 -rays has been developed and applied to self-absorption correction in routine -ray spectrometry for environmental samples composed of unknown matrix elements. Experimental values of the mass attenuation coefficient obtained by the method agree well with calculated values for samples of known elemental composition which was determined by means of chemical analysis.     

Artifact (α, x) Reaction Gamma-Ray Peaks Reported as 241Am Decay Gamma-Rays; Comments to the Paper by Abdulrahman Abdul-Hadi, J. Radioanal. Nucl. Chem., 231 (1998) 147

Review of a recent paper reporting the -ray energies and intensities associated with the decay of ²⁴¹Am has resulted in the conclusion that some of the rays were misidentified. The misidentified -rays are not associated with the decay of ²⁴¹Am, but rather are prompt -rays from alpha-induced reactions.     

Reaction of N-Acyl-γ-aminobutyric Acids with 3-Ethoxycarbonylbenzotriazole 1-Oxide

Reactions of ,-dehydrodipeptides containing a terminal -aminobutyric acid residue with 3-ethoxycarbonylbenzotriazole 1-oxide at 90-100°C result mainly in cleavage of the peptide bond. In the cold, the corresponding ethyl ester and N-acyl--butyrolactam are formed. Analogous reactions with N-benzoyl- and N-benzyloxycarbonyl--aminobutyric acids leads to formation of the corresponding ethyl esters.     

Influence of cyclodextrins on nitrosation of drugs

The World Health Organization issued a nitrosation procedure (NAP Test) which allows to carry out nitrosation under standard conditions. It has proved that the in vitro reaction rates of the fast nitrosatable drugs piperazine, cimetidine and ethambutol are not influenced by -, - and -cyclodextrin. On the contrary, -, -cyclodextrin and heptakis-2,6-di-O-methyl--cyclodextrin enhance the nitrosation of the slower nitrosatable 1-ephedrine and fencamfamine significantly. This possible reaction must be considered if nitrosatable drugs are formulated with cyclodextrins to be administered to human beings.     

Decay of 1.643-hr 95Ru to 95Tc

The decay of ⁹⁵Ru has been investigated by means of -ray spectroscopy. The ⁹⁵Ru nuclei were produced by the reaction ⁹²Mo(,n)⁹⁵Ru at the beam energy of 17 MeV. High-purity Ge detectors have been used singly and in coincidence to study -rays in the decay of ⁹⁵Ru to ⁹⁵Tc. 132 -rays are reported, among them, energies and intensities for 127 transitions have been determined. A decay scheme of ⁹⁵Ru with 31 levels is proposed which accommodates 127 of these transitions. Spins and parities for three new levels are proposed from calculated logft values, measured -ray branching ratios, and in-beam experiment results of the daughter nucleus ⁹⁵Tc.     

New weak γ-lines following the α-decay of249Cf

The -spectrum following the -decay of²⁴⁹Cf was reinvestigated using high resolution coaxial and planar HPGe detectors. Accurate energy and intensity values of 44 -rays were measured, among which 23 were reported for the first time.     

Synthesen von kernsubstituierten N,N-Diphenyl-β-alaninen

Zusammenfassung N,N-Diphenyl--alanine mit Substituenten in einem oder in beiden Phenylresten wurden durch Umsetzung von entsprechenden Diphenylaminderivaten mit -Propiolacton erhalten. In ähnlicher Weise reagierte Diphenylamin mit -Butyrolacton zu -(N,N-Diphenylamino)-buttersäure. 4,4-Diäthyldiphenylamin und 2-Chlor-6-methyl-diphenylamin wurden als Ausgangsmaterialien für die entsprechenden -Alanine hergestellt.

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N.N-Diphenyl--alanines with substituents in one or in both of the phenyl groups were synthesized by reactions of the corresponding diphenylamine derivatives with -propiolactone. Similarly diphenylamine reacted with -butyrolactone to give -(N.N-diphenylamino)-butyric acid. 4.4-Diethyldiphenylamine and 2-chloro-6-methyldiphenylamine were prepared as starting materials for the corresponding -alanines.

     

Synthesis of two regiospecific isomers of monotosyl-γ-cyclodextrin

Tosylation of -cyclodextrin in an aqueous alkaline solution gave two regiospecific isomers (2-monotosyl--cyclodextrin(1) and 6-monotosyl--cyclodextrin(2)), that could recognize and catalyze small sized guest molecules; 2-monotosyl--CD recognized small sized guest molecules more effectively than did 6-monotosyl--CD.     

Levels of221Fr fed by the225Ac α-decay

The -decay of²²⁵Ac to²²¹Fr excited states has been reinvestigated using high-resolution -spectroscopy for single and - coincidence measurements. Twenty nine²²¹Fr nuclear excited states were proposed; ten of which are newly observed.     

Reaction mechanism and principles of choosing catalysts for selective oxidation at C?H bonds

Reaction mechanism for selective oxidation of organic compounds at C–H bonds is discussed. The criteria of selecting catalysts for these reactions have been formulated; 1) fast heterolytic activation of C–H bonds; 2) relatively slow primary activation of oxygen; 3) fast diffusion of oxygen vacancies; 4) fast electron transfer from the adsorbed substrate to catalyst.

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C–H . : 1) C–H ; 2) ; 3) ; 4) .

     

The decay of188Re

The -ray spectra of¹⁸⁸Re decay have been studied by using two Ge/Li/ spectrometers and a three parameters /E-E-T/ List coincidence system. The energies and relative intensities of 52 -rays and cascade relations of 14 -rays are determined. Ten new -rays: 155 /633–478/, 984, 1096, 1463, 1332, 1530, 1574, 1810, 1867, and 1937 keV have been identified. The 155 /633–478/ transition is confirmed and its relative intensity is estimated by means of coincidence experiment. 24 levels of¹⁸⁸Re are assigned. Among those, 6 levels are first put into the decay scheme of¹⁸⁸Re. In addition to 1443 keV and 1937 keV levels, 1685, 1729 and 1965 keV levels are also observed in the decay of¹⁸⁸Ir and other reaction studies. The 1948 level is recently suggested in the¹⁹⁰Os/p, t/¹⁸⁸Os reaction. The 486 keV and 811 keV -transitions are also put into the level scheme of¹⁸⁸Re. The ^– decay branching ratio is deduced.     

Phase solubility analysis in studying the interaction of nifedipine with selected cyclodextrins in aqueous solution

The solubilizing potential and complexing tendencies of six cyclodextrins (CyD) with nifedipine in aqueous solution were evaluated using phase solubility methods. Solubility curves of nifedipine with -CyD, 2-hydroxypropyl--CyD (2HP--CyD) and 2-hydroxypropyl--cyclodextrin (2HP--CyD) were classified as type A_L, while for heptakis (2,6-dimethyl)--CyD (DIMEB), randomly methylated--CyD (RAMEB) and -CyD, A_p type phase behaviour was observed. Stability constants, calculated from phase solubility diagrams, decreased in the order: DIMEB > RAMEB > -CyD > 21HP--CyD > -CyD > 2HP--CyD.