Fast non-destructive determination of silicon in coal by means of /n,n′ γ/ and /n, γ/ processes

The possibilities were evaluated of nondestructive determination of silicon content in large-scale samples of coal /about 20–50 kg/, based on the spectrometry of prompt -radiation from processes /n, n /, E=1779 keV and /n, /, E=3539 keV and 4935 keV. The neutron sources were either²⁴¹Am–Be or²⁵²Cf located additionally in D₂O moderator. A Ge/Li/ detector was used for -radiation detection. In exposure times of up to 2 h, the detection limits of 1.3% and 0.9% and accuracies of silicon determination of 0.66% and 0.40% have been achieved in case of /n, / and /n, n / processes, respectively.     

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.     

M Spectra of the Rare Earth Elements Measured with an Ultra-Thin Window Si(Li) Detector

The oxides of the rare earth elements 57Z71 were excited by electrons with an energy between 3 and 15keV. X-rays were detected by an energy dispersive Si(Li) spectrometer, with an ultra-thin polymer entrance window. Due to the limited resolution of this type of spectrometer, the M spectra of the rare earths appear to consist of only four peaks: M, M,, M, and M₂N₄. The net height of these peaks relative to that of M, was used as a measure of the relative intensity. For 3keV electrons, a continuous decrease of the relative intensity of M with increasing Z was observed, ranging from approximately 90% for 57 La to less than 10% for 71 Lu. This behaviour is in agreement with a model involving a gradual filling up of the levels N6 and N7 with increasing Z. The relative intensity of M is lower than that of M by about a factor of 5, whereas M₂N₄ is approximately half as intense as M.     

Gas chromatography ofγ-valerolactam andγ-valerolactone from reductive amination of butyl levulinate

Summary The-valerolactam and-valerolactone in the reductive amination products of butyl levulinate in water or alcoholic medium, after removing most of the light fractions, ammonia, and water or alcohol, have been determined by isothermal gas chromatography using phenylether or isoamyl salicylate as the internal standard. With the thermal conductivity detector, a column of 6 mm I. D., 2 m long copper tubing packed with 25% glycol adipate/chromosorb-W was used, with hydrogen as the carrier gas. The accuracy was ± 0.4% for-valerolactone and ± 0.5% for-valerolactam. Using the hydrogen flame ionization detector, a column of 3 mm I. D., 2 m long stainless steel tubing packed with 10% glycol adipate/chromosorb-W was used, with nitrogen as the carrier gas; the accuracies for-valerolactone and-valerolactam were ± 0.5% and ± 0.8% respectively.

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Zusammenfassung Unterwirft man Butyllävulinat in wäßrigem oder alkoholischem Milieu der reduktiven Aminierung, so entstehen unter anderem-Valerolactam und-Valerolacton. Diese wurden nach weitgehender Entfernung der flüchtigen Anteile (Ammoniak, Wasser oder Alkohol) durch isotherme Gaschromatographie unter Verwendung von Phenyläther oder Isoamylsalicylat als interne Standards bestimmt. Mit einem Wärmeleitfähigkeitsdetektor wurde eine 2 m lange Säule mit 6 mm i. D. aus Kupferrohr mit einer Füllung aus 25% Glykoladipat und Chromosorb W verwendet, mit Wasserstoff als Trägergas. Die Genauigkeit betrug ± 0,4% für-Valerolacton und ± 0,5% für-Valerolactam. Wurde hingegen ein Ionisierungsdetektor mit Wasserstoff-Flamme verwendet, so diente eine 2 m lange Säule mit 3 mm i. D. aus rostfreiem Stahl mit einer Füllung aus 10% Glykoladipat und Chromosorb W und Stickstoff als Trägergas. Die Genauigkeit betrug dann ± 0,5 bzw. ± 1,8%.

     

Preparation ofγ-butyrolactones by oxidation of monofunctional tetrahydrofuran derivatives

Conclusions The major products in the oxygen-oxidation of tetrahydrofurfuryl alcohol, its esters, and an ester of 2-tetrahydrofurancarboxylic acid are -butyrolactone and the corresponding -substituted -butyrolactone.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 577–579, March, 1972.     

Effect of cascade coincidences on the efficiency calibration of a gamma-X detector

The sensitivity on n-type gamma-X detectors for low-energy X- and -rays calls for coincidence corrections in the efficiency calibration that do not apply to the calibration of p-type detectors. Corrections were calculated for the effect of cascade coincidences between -rays, X-rays, annihilation radiation, and bremsstrahlung, for 15 radionuclides frequently used for efficiency calibration. Experimental results are presented for a -X detector with 37% relative efficiency at distances from 0.9 to 17.5 cm. After coincidence correction smooth efficiency curves were found for the energy range 12 to 2750 keV, even for the position closest to the detector.     

Studies in dipyridyl chemistry. VII. Sulfur trioxide sulfonation of γ,γ′-dipyridyl

Reaction of ,-dipyridyl with sulfur trioxide at room temperature gives ,-dipyridyld'isulfotrioxide, which latter on heating at 200° gives ,-dipyridyl-sulfonic acid. Salts of ,-dipyridyl-3-sulfonic acid are prepared, among them the potassium, sodium, barium, and 3-cyano-,-dipyridyl salts.For Part VI see [1].     

A practical approach for self-absorption correction in210Pb gamma-spectrometric dating

Self-absorption correction of low-energy (<100 keV) -radiation is a much debated subject when applying low-energy -rays for dating purposes. Some investigations have hitherto focused on the possibility of using either irradiating of the sample and subsequent absortiometry or introducing physical correction. In the present paper an automatic procedure was elaborated using the occurrences of other low-energy -lines in the sample, those of²³⁴Th. Theoretical considerations are described on the basis of the mass absorption coefficients as a function of energy and atomic number. These considerations are verified by experiments with rock forming oxides and carbonates mixed with Standard Reference Material. Finally, an example is given for the application of the self-absorption correction approach.     

Zur gruppentheoretischen Bestimmung der Atomzustände in Ligandenfeldern

Zusammenfassung Es wird vorgeschlagen, die Bezeichnungen weak-field-Methode bzw. strong-field-Methode durch (L)-Methode bzw. ()-Methode zu ersetzen.Nach einer kurzen Einführung in die ()-Methode wird mit den Mitteln der Gruppen-und Darstellungstheorie eine Formel abgeleitet, mit deren Hilfe man schnell Rasse und Multiplizität der Terme eines Komplexions in der ()-Methode angeben kann. Einige Spezialfälle dieser Formel und die systematische Bestimmung der ()-Funktionen werden erörtert.

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It is suggested that the misleading designations weak field method and strong field method be replaced by (L) method and () method, respectively.Following a brief introduction to the () method an equation is derived by group theoretical means which leads to rapid classification of the () terms. Several special cases and short cuts are discussed as well as the systematic determination of the () functions.

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Résumé Le remplacement des termes «méthode du champ faible» et «méthode du champ fort» par «méthode (L)» et «méthode ()» est proposé.Après une introduction dans la méthode () une formule est dérivée à l'aide de la théorie des groupes et des représentations, qui donne la représentation irréductible et la multiplicité des termes d'un ion complexe dans le cadre de la méthode (). Quelques cas spéciaux de cette formule et la détermination systématique des fonctions (/gG) sont discutés.

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Ich danke Herrn Professor Dr. H. Hartmann für den Hinweis auf das vorliegende Problem und der Deutsehen Forschungsgemeinschaft für ein Stipendium.     

Spin conversion of positronium in paramagnetic solutions studied by age-momentum-correlation method

Correlated measurement of the lifetime and of the lineshape of the 511 keV annihilation radiation of positrons (age-momentum correlation, AMOC) has become a powerful tool for investigating reactions of positron or positronium in condensed matter as a function of time. The beam-based ⁺ AMOC method installed at the Stuttgart relativistic positron beam facility (E _kin ^e+ 4MeV) offers substantial advantages over the conventional E coincidence technique resulting in a fast data taking due to the unity detection efficiency of the ⁺ scintillator which provides the start signal for the lifetime measurement. In this paper the application of AMOC to positronium chemistry is illustrated by the study of spin conversion of positronium in the system methanol/HTEMPO as a function of HTEMPO (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, a paramagnetic solute) concentration. The same technique can be applied to other systems and other reactions in positronium chemistry, e. g., oxidation or complex formation.     

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 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.     

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.     

Macromolecular conformations at the water-air interface: Interactions between alpha and beta conformations of polypeptides

Bidimensional miscibility between alpha and beta conformations of polypeptides was investigated at the water-air interface in the 15°–30°C temperature range. The polypeptides were poly--methyl-L-glutamate (PGMG), poly--benzyl-L-glutamate (PGBG) and poly--benzyl-L-aspartate (PBBA). The polypeptide conformations, alpha or beta, were checked by IR spectroscopy using the MIR technique.The spreading isotherms for mixed monolayers alpha-PGMG/alpha-PGBG and beta-PGMG/beta-PBBA showed bidimensional miscibility both for alpha-alpha and beta-beta mixtures.For the alpha-alpha system, attractive interactions among the polypeptide alphahelices were found (G_mix<0) and the driving factor appeared to be the entropic one (packing). Compressibility moduli and surface potential measurements showed a fluidification effect of alpha-PGBG on mixed monolayers. In the case of beta-beta mixed monolayers, ideal behaviour was observed and no fluidification effect detected.Scanning electron micrographs made on collapsed monolayers showed hexagonal structures for alpha-alpha mixtures and no well-defined or characterized features for the beta-beta system.     

New derivatives of 4-quinaldinol

The reactions of 1, 1, 3-trichloro-1-propene and also 1, 1, 1-trichloro-2-propene with acetoacetic ester gave -(, -dichlorallyl)acetoacetic ester (I). In the reactions with aniline and o- and p-toluidines, the corresponding -(, -dichloroallyl)--arylamino-crotonic esters were produced, thermal cyclization of which gave 2-methyl-3-(, -dichloroallyl)-4-hydroxyquinoline (II) and its 6CH₃- (III) and 8CH₃- (IV) homologs. With phosphorus oxychloride, II–IV gave the corresponding 4-chloro-substituted quinolines (V–VII); with concentrated sulfuric acid, II–VII were converted into the corresponding -quinolinylpropionic acids VIII–XIII.For part XI, see [5].     

Synthesis and sorption properties of new hybrid chelating sorbents with β-alanine functional groups

A series of -aminopropylsilylated sorbents was obtained from different oxide supports (silica gels, silica fillers, macroporous glasses, alumina) and by the direct synthesis (hydrolytic polycondensation of tetraalkoxysilanes with -aminopropyltriethoxysilane). The highest degree of immobilization was achieved for silicas, while the most convenient solvent was methanol. Sorbents with -alanine functional groups were obtained by the subsequent reaction with acrylic acid. The degree of -carboxyethylation was 1.3–1.9, and the highest content of functional groups (v_COOH = 3.23 mmol g^–1) was achieved for carboxyethylated xero gel synthesized by the copolycondensation of tetraethoxysilane with -aminopropyltriethoxysilane. The sorbents containing -alanine possess a higher selectivity of Cu²⁺ ion sorption than the initial -aminopropylsilylated sorbents.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2620–2625, December, 2004.     

Heterocyclic compounds

The and isomers of 1-allyl-3-methyl-4-(3-alkyl-1-propynyl)-4-piperidols were synthesized by the condensation of the and isomers of 1-allyl-3-methyl-4-ethynyl-4-piperidol with piperidine (morpholine) and paraformaldehyde in anhydrous dioxane in the presence of cuprous chloride.See [1] for Communication I.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1652–1653, December, 1970.     

Microcalorimetric Evaluation of Precipitation in Cu–2Be–0.2Mg

Beryllium precipitation from the Cu-rich matrix in a Cu–2 mass% Be–0.2 mass% Mg alloy homogenized and quenched from 1073 K was studied by differential scanning calorimetry (DSC). The DSC traces showed two main exothermic effects, A and B, each comprising two subeffects: A₁ and A₂ , and B₁ and B₂ respectively. Effects A₁ and A₂ correspond to the precipitation of GP zones and subsequent overlapping and independent precipitation of the phase. Only at very low heating rates can be inherited from GP zones. Effects B₁ and B₂ correspond to heat evolved during transitions to the states with and phases, respectively. Heat effect A can be quantitatively described in terms of solid solubilities before and after precipitation, and of the precipitation heats of the phases involved. The heat content of the combined GP zone/ phase precipitation effect was proportional to the number of beryllium atoms precipitated, yielding an average value of 21 kJ mol^–1 beryllium for beryllium precipitation. It was shown that the phase arises from the combined transition from states with GP zones and phases, whereas arises from the transition of states with and phases. The apparent activation energies associated with GP zones and , and phases are 1.16±0.08, 1.18±0.07, 1.37±0.08 and 1.74±0.09 eV, respectively. These values are discussed in terms of the mobility of dissolved atoms related to the concentrations of excess vacancies and solute-vacancy complexes, and the direction of plate-like precipitate growth (either normal or perpendicular to the plate). It is inferred that the main roles of magnesium are to decrease the amount and rate of GP formation, to enhance the volume fraction of and to suppress the discontinuous precipitation of .This revised version was published online in November 2005 with corrections to the Cover Date.