A photoplate calibration technique applied to the determination of hafnium in zirconium by SSMS

A photoplate calibration procedure is suggested for spark source mass spectrometry /SSMS/ with photoplate detection. The technique uses the Churchill two-line method applied to the two stable isotopes of copper. The calibration curve thus obtained is split into fragments and each fragment is approximated by a polynomial. The method was applied for the quantitative determination of Hf as impurity in zirconium sponge obtained from a pilot plant dedicated to the depletion of the hafnium content in zirconium by fractional crystallization.     

Koordinationsverbindungen von Aminoacridin-N-oxiden mit Metallthiocyanaten der 3d-Reihe

Coordination Compounds of Aminoacridine-N-oxides with Thiocyanates of the 3d Metals . Reactions of thiocyanates of the 3d metals with selected aminoacridine-N-oxides in homogeneous dilutions of N,N-dimethylformamide form compounds of the type [M(AAcNO)_a(DMF)_b(NCS)₂] · cDMF and [M′(AAcNO)_d(DMF)_e(NCS)₃] · fDMF, M = Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺; M′ = Cr³⁺, Fe³⁺; AAc^INO = 3,6-diamino-2,7-dimethylacridin-N-oxide, AAc^IINO = 3,6-bis(dimethylamino)acridin-N-oxide, AAc^IIINO = 2-ethoxy-6,9-diaminoacridin-N-oxide; a = 1, 2, 3, 4; b = 0, 1; c = 0, 1, 2, 3; d = 1, 2, 3; e = 0, 1, 2; f = 0, 1, 2, 3. The complexes are characterized by IR (4000–200 cm^?1) and UV-VIS spectra in solutions and solids and by EPR and conductivity investigations.     

THE KINETICS OF REDUCTION OF CYTOCHROME c BY SEMI-REDUCED FLAVIN

Abstract— Flavin mononucleotide radicals, FMNH', generated by laser flash photolysis of FMN in the presence of the electron donors, histidine, guanosine monophosphate or EDTA, were found to reduce cytochrome c with an apparent rate constant of 6 ± 10⁷ M ⁻¹ s⁻¹. These flash photolysis results were, however, complicated by the electron donor radicals formed simultaneously which, particularly with EDTA, also lead to reduction of cytochrome c. Pulse radiolysis of a nitrous oxide saturated aqueous solution of FMN containing a high concentration of HCOONa, leads to the exclusive formation of FMNH'. By adding small concentrations of cytochrome c to this solution, a rate constant of 4.0 ± 10⁻¹ M ⁻¹ s⁻¹ was obtained for the reduction of cytochrome c by FMNH'. Replacement of the HCOONa by EDTA in such solutions leads to further routes for reduction of cytochrome c on radiolysis. as in the photolytic situation. The relevance of these results to flavin-photosensitised reduction of cytochrome c and other components of the mitochondrial electron transport chain is discussed.     

Molecular orbital study of gas phase basicities of carbofunctional derivatives of group IVB elements; stereochemical control

The gas phase basicities of a series of carbofunctional derivatives H₃M(CH₂)_nX (M = C, Si, Ge; X = NH₂, OH, F; n = 1–3) were investigated by the semiempirical CNDO/2 method. The calculations indicate that the electronic effects of silyl- and germyl-substituents differ greatly from the effect of simple alkyls. Moreover, in contrast to simple carbon derivatives, the overall nature of the electronic effects of siliyl- and germyl-substituents is crucially influenced by the molecular conformation.     

2-arylfuro [2,3-b] quinoxalines

2-Arylfuro[2,3-b]quinoxalines were obtained by cyclization of 2-phenacyl-3-quinoxalones in the presence of polyphosphoric acid or a mixture of phosphorus oxychloride and phosphorus pentachloride.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 259–260, February, 1973.     

Structural investigation of the lipopolysaccharide ofYersinia pseudotuberculosis of type IB

Summary Using the chromato-mass spectrometry of the methylated sugars formed in the hydrolysis of the fully methylated lipopolysaccharide fromYersinia pseudotuberculosis of type IB the nature of the glycosidic bonds between the monosaccharide residues has been established. The hapten formed in the partial hydrolysis of the lipopolysaccharide has also been studied by methylation. The results obtained have confirmed the results of an investigation of the methylated lipopolysaccharide; they have enabled an idea to be put forward of the composition of the repeating unit of the O-specific side chains of the lipopolysaccharide.Pacific-Ocean Institute of Bioorganic Chemistry of the Far-Eastern Scientific Center of the Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 563–570, September–October, 1975.     

Static-lattice theory of crystalline HCN.: II. Elastic and piezoelectric properties

An effective dipole potential is used to calculate the elastic and piezoelectric coefficients for a static-lattice model of tetragonal HCN, using the generalized thermodynamic theory of internal strain. The model is unstable with respect to molecular rotation away from the tetragonal axis, owing to the use of a point effective dipole. An improved potential would represent the molecule as a set of polarizable point dipoles. Isotropic pressures makes HCN expand along the tetragonal axis as it contracts perpendicular to the axis, because of strong elastic cross-linking. The piezoelectric stress coefficient for shear strain is dominated by the contribution from molecular rotation. Both physical and thermodynamic coefficients are calculated; the differences between the coefficients, which arise from the permanent polarization in HCN, are especially marked in the strain coefficient.     

The magnetic susceptibilities of cobaltocene and chromocene

The magnetic susceptibilities of cobaltocene and chromocene have been measured between 83 and 293 K; for cobaltocene the results suggest an appreciable orthorhombic splitting of the ²∏(σ²πδ⁴ ground state, whilst for chromocene the data provide further support for the ³Δ(σδ³) ground state previously deduced.     

The microwave spectrum and dipole moment of 1,1-diflurobenzocyclopropene

The rotational spectrum of 1,1-difluorobenzocyclopropene, measured in the X- and R-bands, has been analysed to give the rotational constants in the ground and first four vibrational states. These constants are in agreement with a structure based on those of crystallographically determined related molecules. Indirect evidence is adduced that the carbon skeleton is indeed planar. The dipole moment in the ground (3.57₂ ± 0.02 D) and first excited state (3.54 ± 0.03 D) has been determined through an analysis of the second-order Stark effect. This high value implies considerable polarisation of the π-electron framework.     

Radiochemical studies of free-radical vinyl polymerizations. VI. Polymerization of methyl methacrylate in the presence of organotin PVC stabilizers

¹⁴C-Azoisobutyronitrile was used to initiate polymerizations of methyl methacrylate in the presence of the organotin compounds: tetrabutyltin, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin di(ethyl mercaptide), dibutyltin di(dodecyl mercaptide), and dibutyltin dichloride. Only dibutyltin dichloride affected rates of polymerization significantly, and this was ascribed to an increase in the velocity constant k_p for the propogation reaction. No evidence was obtained for radical displacement reactions of the polymer radicals with bonds between tin and carbon, oxygen, sulfur, or chlorine. Transfer activity exhibited by the mercaptides was ascribed to traces of thiol impurity, possibly formed during storage. The relevance of these results to the mechanism of stabilization of poly(vinyl chloride) is briefly discussed.