Vibronic intensity borrowing. Deuterium effect and emission—absorption asymmetry of the S1---S0 transition in pyrene

The intensities of the vibrationally induced bands in the S₁---S₀ emission and absorption spectra of pyrene-h₁₀ and -d₁₀ are measured and analysed. Several new expressions are reported which relate the deuterium effect and emission—absorption asymmetry of induced spectra to the vibronic coupling mechanism.     

Solid-state polymerization of 1,2,3,4-diepoxybutane initiated by cobalt-60 γ-radiation

The solid-state polymerization of 1,2,3,4-diepoxybutane appears to proceed “insource” by an ionic mechanism and has an overall activation energy of 0.4 kcal./mole with an intensity dependency of 0.99. There is a rapid increase in the rate of polymerization just prior to the melting point and a very low rate for the liquid-phase reaction. Limiting conversions of 5% polymer are observed at ?196°C. for irradiation in vacuo. No limiting conversion was observed when the monomer was polymerized in the presence of air or in vacuo at ?78°C. Under all polymerization conditions the reactions were characterized by the absence of an induction period.     

Direct observation of eta 2-imine formation through beta-H abstraction between amide ligands. Neutron and X-ray diffraction structure of a dihydride imine ditantalum complex

Reactions of Ta(NMe2)5 with D2SiR'Ph (R' = Me, Ph) were found to give a dideuteride eta 2-imine complex (Me2N)3Ta(mu-D)2(mu-N-eta 2-N,C-CH2NMe)Ta(NMe2)3(1-d2) through C-H activation of an amide ligand via beta-H abstraction, and the structure of 1 was confirmed by single crystal neutron and X-ray diffraction.     

Mössbauer investigation on the crystal field splitting of Fe ion in zinc fluosilicate

The Mössbauer quadrupole interaction ΔE_Q of the Fe²⁺ ion has been measured with 2% at. ⁵⁷Fe in ZnSiF₆·6H₂O, between 1.3 and 20°K. The sign of ΔE_Q (< 0) has been determined by using a single crystal absorber. These results are interpreted in terms of a trigonal crystal field potential that splits the Fe²⁺ orbitals into a ground state singlet and a first excited doublet whose distance is much smaller than that reported for FeSiF₆·6H₂O, in reasonable agreement with previous EPR measurements.     

Heterocyclic N-glycosyl derivatives—XIII: Reaction of 6-chloropurine and benzotriazoles with acetylated glycals

Acid-catalysed reactions of tri-O-acetyl-D-glucal with benzotriazole, 5,6-dimethylbenzotriazole, 5,6-dichlorobenzotriazole and 6-chloropurine have been found to give anomeric mixtures of the corresponding 2′,3′-unsaturated N-glycosyl derivatives with the α-anomers preponderating. When tri-O-acetyl-D-galactal was used the 3′,4′,6′-tri-O-acetyl-α- and β-D-lyxo-hexopyranosyl nucleoside analogs were obtained. The conformation and anomeric configuration of all the N-glycosyl compounds obtained were assigned by NMR studies.     

Determination of227Ac in geological materials through neutron activation and alpha-spectrometric assay of induced228Th

A new route has been developed for the micro-determination of²²⁷Ac in geological materials by neutron activation. The method is based on intense neutron irradiation of the analysed samples followed by separation and α-spectrometric determination of²²⁸Th, the β-decay product of the 6.1 hrs²²⁸Ac isotope formed. Two alternatives are considered for analysis related to the origin of the analysed matrix. The high sensitivity of the method is documented by the determination of 10^?17 g²²⁷Ac/g sample. The method is successfully applied for age determination of five uranium containing materials and old uranium glass from Bohemia, CSSR.     

Two-phase titration of organic ammonium ions with lauryl sulphate and methyl yellow as indicator

Conditions for determination of quaternary ammonium compounds and amines by two-phase titration have been calculated on the basis of extraction constants for the ion-pairs between the titrant (lauryl sulphate), the indicator (Methyl Yellow) and the sample. Methods for determination of extraction constants are presented. The precision and selectivity of the method are demonstrated by titrations of ammonium ions with different structures and degrees of substitution. The results are in agreement with the theoretical calculations.     

Trennung von V,Cr und Mn aus Stahl und Aktivierungsanalyse der Legierungselemente mit 14 MeV-Neutronen

The elements are separated from iron by solvent-extraction. Cr, V and Mn are separated by ion-exchange chromatography with a strong acidic cation-exchanger. The elements are determined by 14 MeV-neutron activation analysis using γ-spectroscopy. The method is suitable for a concentration range of 0.05 to 5%.     

Study of occupational health impact of atmospheric pollution on exposed workers at an iron and steel complex by using neutron activation analysis of scalp hair

The occupational health impact of atmospheric pollution on exposed workers at one iron and steel complex was studied by instrumental neutron activation analysis of workers' hair samples and medical examination. The experimental results indicate that there is a positive correlation between the high inhalation amounts of iron and other trace elements by the exposed workers and the symptom of their high blood pressure and hypoglycemia, which implies that the atmospheric environment polluted by iron and steel industry has an adverse health impact on the exposed workers. The measures to relieve and abate the occupational diseases caused by air-borne particulate matter should be taken     

Evaluation of some essential and trace elements in diets from 3 nurseries from Juiz de Fora, M.G., Brazil, by neutron activation analysis

A study was made in diets offered to a group of pre-school children,whose mean age was 67 months and remained the whole day in three day carecenters from Juiz de Fora, M.G., Brazil. For sampling, the duplicate portiontechnique was used, and the diets were collected and analyzed separately eachday in the 3 nurseries. Instrumental neutron activation analysis was appliedto the determination of 16 elements. The daily dietary intake values werecompared to the RDA (children 4–6 years old). Based on this reference,Ca, Fe, Se and Zn were found to be deficient, Mg and Mn were comparable tothe RDA and the Cl and Na concentrations were higher compared to their RDA.For the other elements measured, there are no RDA's for children.