Mischligandenderivate des 1:1-Th(IV)—DTPA-Chelates mit Milchsäure,Mandelsäure und o-Hydroxynaphthoesäuren

Potentiometric studies of the mixed ligand derivatives of 11-Th(IV)—DTPA chelate (whereDTPA=diethylene-triamine pentaacetic acid) with certain secondary ligands, such as lactic, mandelic and o-hydroxynaphthoic acids have been carried out. The pH-titrations of the reaction mixtures containing 111 molar ratio of metal ion toDTPA to secondary ligand have shown the formation of 111 ternary complexes at higher pH (8). The equilibrium constants of the resulting mixed complexes have been determined at 30±1°C and =0.1 (KNO₃) and the order of stability in terms of secondary ligands has been found to be o-hydroxy naphthoic acids>mandelic acid>lactic acid.

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Coordination behaviour of azines towards iron(II), palladium(II) and platinum(II)

Summary The coordination behaviour of Schiff bases derived from the condensation of some of the heterocyclic aldehydes with hydrazine hydrate, towards Fe^II, Pd^II and Pt^II, has been studied. The 1:1 and 1:2 molar reactions of MCl₂ with the Schiff bases result in coloured solids which have been characterised by elemental analysis, conductance and magnetic measurements. The mode of bonding has been deduced from i.r. and n.m.r. (¹H and¹³C) studies.     

Approximate representations and pointwise bounds for solutions of a class of non-linear boundary value problems

This article establishes an approximation in the implicit form (within the limits of error) of solutions of [L + M(ε)]x = ρ(t, x) satisfying the limiting conditions x^(2k)(0) = x^(2k+1)(τ) = 0, k = 0,1,…, n?1, L being a linear differential operator of degree equal to 2n with constant coefficients and M(ε) a differential operator of an inferior order enabling the absorption terms and the coefficients to vary slowly. f(t,x) is continuous in the sense of Lipschitz, not negative, monotonous, increasing in x and of the saturation type.     

Helix reversals as bad neighbors to liquid crystal organizations in cholesteric states and thermally reversible gels of poly(ALKYL isocyanates)

While the temperature dependence of the lyotropic cholesteric pitch of the single helical sense poly ((R)-2,6-dimethylheptyl isocyanate) is in line with theory, comparable data on this state produced by chiral doping of the lyotropic nematic state of poly(n-hexyl isocyanate) could suggest an interplay between the supramolecular chirality of the liquid crystal and the dynamic equilibrium of the left and right hand helical blocks in this otherwise racemic polyisocyanate. The exclusion of helix reversals, as undersireable kinks in the liquid crystal organization, could play a role in this effect. Such helix reversal exclusions can also explain the peculiar chiral optical changes associated with the thermally reversible gelation of poly(n-hexyl isocyanate) copolymers in hydrocarbon solvents. These gels likely arise by entering the broad biphasic region of the Flory phase diagram leading to the formation of liquid crystal aggregates.     

The Young Julian Schwinger. II. Julian Schwinger at Columbia University

In this series of articles the life and work of the young Julian Schwinger are explored. In this second article in the series, Schwinger's work at Columbia University, up to the completion of his doctorate and a little after, is discussed. Schwinger soon matured into a brilliant theoretical physicist.     

Preliminary evaluation of laser-induced breakdown spectroscopy for tissue classification

Laser-induced breakdown spectroscopy (LIBS) is an on-line, real-time technology that can produce immediate information about the elemental contents of tissue samples. We have previously shown that LIBS may be used to distinguish cancerous from non-cancerous tissue. In this work, we study LIBS spectra produced from chicken brain, lung, spleen, liver, kidney and skeletal muscle. Different data processing techniques were used to study if the information contained in these LIBS spectra is able to differentiate between different types of tissue samples and then identify unknown tissues. We have demonstrated a clear distinguishing between each of the known tissue types with only 21 selected analyte lines from each observed LIBS spectrum. We found that in order to produce an analytical model to work well with new sample we need to have representative training data to cover a wide range of spectral variation due to experimental or environmental changes.     

Multivariate calibration of spectra obtained by Laser Induced Breakdown Spectroscopy of plutonium oxide surrogate residues

Laser Induced Breakdown Spectroscopy (LIBS) was used to determine elemental concentration of plutonium oxide surrogate (cerium oxide) residue for monitoring the fabrication of lanthanide borosilicate glass. Quantitative analysis by LIBS is affected by the severe limitation of variation in the induced plasma due to changes in the matrix. Multivariate calibration was applied to LIBS data to predict the concentrations of Ce, Cr, Fe, Mo, and Ni. A total of 18 different samples were prepared to compare calibration from univariate data analysis and from multivariate data analysis. Multivariate calibration was obtained using Principal Component Regression (PCR) and Partial Least Squares (PLS). Univariate calibration was obtained from background-corrected atomic emission lines. Calibration results show improvement in the coefficient of determination from 0.87 to 0.97 for Ce compared to univariate calibration. The root mean square error also reduced from 7.46 to 2.93%. A similar trend was obtained for Cr, Fe, Mo, and Ni also. These results clearly demonstrate the feasibility of using LIBS for online process monitoring in a hazardous waste management environment.     

121Sb Mössbauer spectral and related studies on Sb(III) complexes

The bonding and structural features of antimony(III) complexes of the type, (PrⁱO)SbL and Sb₂L₃ are described (where L is the dianion of semicarbazone or thiosemicarbazone). The Mössbauer spectra are typical of Sb(III) complexes in which the non-bonding pair of electrons is stereochemically active. The thiosemicarbazone complexes show more negative isomer shifts compared to the semicarbazone complexes.     

Relaxation intensity in some polyacrylates

Empirical formula suggested by Kita and Koizumi for evaluation of relaxation intensity in a limited range of frequency around the relaxation frequency for the Cole-Cole type distribution has been tested for poly butyl acrylate (PBA), Poly butyl methacrylate (PBMA) and poly isobutyl methacrylate (PiBMA). The relaxation intensity Δε is expressed in terms ofε″ _M , the dielectric loss maxima andW, the frequency separation for half, two thirds or three quarters ofε″ _M , in the form Δε=ε″ _M /[(C ₁/W)+C ₂+C ₃ W], where the numerical constantsC ₁,C ₂,C ₃ are given for the respective type of relaxation.