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Colloidal nanocrystals electronic energy levels are determined by strong size-dependent quantum confinement. Understanding the configuration of the energy levels of nanocrystal superlattices is vital in order to use them in heterostructures with other materials. A powerful method is reported to determine the energy levels of PbS nanocrystal assemblies by combining the utilization of electric-double-layer-gated transistors and advanced ab-initio theory.

The study of semiconducting nanowires is one of the most rapidly growing research areas in materials science and nanotechnology, not only from the point of view of the possible applications, but also regarding the use of the latest developments in the theory. In this paper, we review the general ab initio many-body theory and methods and resume some of our very recent results regarding the structural, electronic, and optical properties of Silicon nanowires (Si-NWs), outlining both the reached achievements and some of the technical aspects necessary to obtain them.

The aim of this work is to elucidate, through density functional calculations, the role of the Si-O interface bonds on the structural, electronic and optical properties of Si nanodots in order to explain the peculiar properties of aged porous Si samples and heavily oxidized Si nanoparticles. For isolated dots we show that the presence of Si=O bond results in a strong reduction of the energy gap. For Si nanodots embedded in SiO 2 we show that both the Si-O bonding and the deformation of the cage play an important role.

The properties of n- and p-doped silicon nanocrystals obtained through ab initio calculations are reviewed here. The aim is the understanding of the effects induced by substitutional doping on the structural, electronic and optical properties of free-standing and matrix-embedded Si nanocrystals. The preferential positioning of the dopants and their effects on the structural properties with respect to the undoped case, as a function of the nanocrystals diameter and termination, are identified through total-energy considerations. The localization of the acceptor and donor related levels in the band gap of the Si nanocrystals, together with the impurity activation energy, are discussed as a function of the nanocrystals size. The dopant induced differences in the optical properties with respect to the undoped case are presented. Finally, the case of B and P co-doped nanocrystals is discussed showing that if carriers are perfectly compensated, the Si nanocrystals undergo a minor structural distortion around the impurities inducing a significant decrease of the impurities formation energies with respect to the single doped case. Due to co-doping, additional peaks are introduced in the absorption spectra, giving rise to a size-dependent red shift of the absorption spectra.

The optical properties of bulk silicon are deeply modified if the material is manipulated at the nanometre scale. In particular the growth of Si nanostructures constitutes today a promising approach for the development of silicon-based light emitting devices. In this context I discuss theoretical results on the optoelectronic properties of low-dimensional silicon structures, e.g. Si quantum wells, quantum wires, quantum dots. The results are compared with recent experimental data.

A rapid and simple analytical method was developed to determine phytate anion in soybeans. The analysis was performed by capillary zone electrophoresis with indirect UV photometric detection. The determination of phytate was carried out with a background electrolyte in which benzoate was the absorbing ion at 254 nm.

The paper presents a brief characterization of capillary zone electrophoresis, a modern analytical separation method with high expediency for practical applications, especially in pharmaceutical analysis. Basic theoretical considerations are presented and discussed to explain the effects of the operational parameters upon the separation efficiency and resolution of species. Descriptions of simple instrumentation and of the analytical procedure itself are given. Experimental examples are given of the separation of mixtures of pharmaceutically important compounds and of the effects of operational parameters, especially pH of BGE and voltage applied. Lastly, the practical application of CZE for analysis of isoxsuprine in commercial preparations is shown.

Summary Immunoreactive insulin (IRI) and immunoreactive glucagon (IRG) were determined in the amniotic fluid from 28 rhesus isoimmunized pregnancies with moderately affected fetuses and from 15 normal pregnancies; in umbilical arterial plasma from nine newborn infants with rhesus haemolytic disease of moderate degree and from 19 normal infants; in plasma from their respective mothers at delivery; and in the urine of 13 normal infants at birth. Levels of IRI and IRG in amniotic fluid from rhesus cases were not different from those of normal pregnancies. IRG was detected in the first voided neonatal urine.