Long-range transport of trace elements to Southern Norway studied by INAA of air filters

The present work is a multi-element study of air concentrations at Birkenes, Southern Norway, based on daily filter samples during 1985. Sixteen elements are determined regularly by INAA; i.e. Na, Al, Cl, Sc, V, Cr, Mn, Fe, Co, Zn, As, Se, Br, Ag, Sb, La. In addition sulfate is determined by ion chromatography and Cu, Ni, Cd and Pb by electrothermal AAS. The main aim of the study is to see whether the air concentrations of long-range transported pollutants have changed significantly since 1979 when a similar study was last performed. Analysis of inter-element correlations in the two data series serves to define four main aerosol compounds: One general pollution, one marine, one soil, and one fossil-fuel component. Classification of air samples with respect to emission areas according to calculated air trajectories indicates from the limited number of 1985 samples analyzed so far that the contribution of air pollutants from Eastern Europe is at least as high as in 1979 while that from Western Europe has decreased. This decrease is evident for Pb in particular.     

Particle discrimination effects in the determination of trace metals in natural fresh waters

Instrumental neutron activation analysis (i.n.a.), atomic absorption spectrometry (a.a.s.), and inductively-coupled plasma atomic emission spectrometry (i.c.p.a.e.s.) have been applied to the determination of Na, K, Mg, Ca, Al, Mn, Fe and Zn in fresh waters containing naturally occurring particles. Scattered results were obtained for the total concentrations of trace metals which were associated to some extent with particles retainable by 0.45-μm filter membranes. Particle discrimination effects are indicated and the fraction of elements included in the final result depends on the method used. For the simultaneous determination of the total concentrations of Al, Mn, Fe and Zn, i.n.a.a. is preferred, as all element fractions present are included in the result. When a.a.s. or i.c.p.a.e.s. is applied, lower results are obtained when particulate matter is present, the results referring only to the acid-soluble low-molecular-weight fraction (< 0.45 μm diameter). When particles are removed prior to the quantifying step, the results obtained on the filtrates by all methods are in good agreement. However, considering the low concentrations of several elements in the separated fractions, i.n.a.a. is most favourable for the determination of aluminium while graphite-furnace a.a.s. is most suitable for zinc. Both methods are applicable for manganese. For Ca, Fe, K, Mg and Na, i.c.p.a.e.s. is recommended.     

Study of structural and electronic transport properties of Ce-doped LaMnO3

The structural and electronic transport properties of La_1−x Ce _x MnO₃ (x=0.0–1.0) have been studied. All the samples exhibit orthorhombic crystal symmetry and the unit cell volume decreases with Ce doping. They also make a metal-insulator transition (MIT) and transition temperature increases with increase in Ce concentration up to 50% doping. The system La_0.5Ce_0.5MnO₃ also exhibits MIT instead of charge-ordered state as observed in the hole doped systems of the same composition.     

Two connected inverse spectral transforms

We establish a transformation which connects the potentials of the one-dimensional Dirac and Klein-Gordon operators. This transformation links the solutions of the nonlinear evolution equations solvable by means of the two inverse spectral transforms which use the Dirac and Klein-Gordon direct and inverse spectral problems.