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The synthesis of thin single-crystalline gallium nitride (GaN) nanowires and their optical and field emission properties are demonstrated. The synthesized GaN nanowires are shown to be single-crystalline wurtzite structures.

Graphite oxide (GO) samples are prepared by using a simplified Brodie method. Electron diffraction study is used for analyzing AB stacking of the layers in the GO samples.

A study was conducted to examine the effectiveness of an Ar neutral beam as a surface treatment for improving the field emission properties of screen-printed carbon nanotubes (CNTs). The results showed that after a neutral beam treatment with an energy of approximately 100 eV the buried CNTs protruded out the binder paste to produce activated CNT emitters.

A selective removal of m-SWCNTs (single walled carbon nanotubes) with small diameters is reported by using HNO3/H2SO4 solution, which could be achieved by adjusting the treatment conditions. The result can be explained by the charge transfer from m-SWNCTs to NO2(super +) dissolved in the HNO3/H2SO4 solution in good agreement with the theoretical calculations.

A three-dimensional simulator is used to analyze the field-emission mechanism of a carbon nanotube (CNT) emitter layer as a surface electron emitter in a triode structure for field-emission display. The field enhancement factor and emission factor of the CNT emitter layer using the experimentally obtained current-voltage (I-V) values and the extended Fowler-Nordheim equation by the least-squares-fitting method is calculated.

Purified native form of secretogranin II, from bovine adrenal medullary chromaffin cell secretory granules, predominantly exhibits beta-sheet and random coil structures with low level of alpha-helicity. Data indicate that it undergoes a pH-dependent conformational change, acidic pH-, and calcium-dependent aggregation. Furthermore, secretogranin II participates in the biogenesis of secretory granules.

The perovskite type [Gd.sub.1-x][Sr.sub.x]Fe[O.sub.3-[Delta]] (x = 0.0, 0.25, 0.5, 0.75 and 1.0) system has been studied by X-rays, Mohr's salt analysis, and Mossbauer spectroscopy. From the results of X-ray diffraction measurement the structure of the [Gd.sub.1-x][Sr.sub.x]Fe[O.sub.3-[Delta]] system is orthorhombic with x values of 0.0, 0.25 and 0.5, and cubic with the x values of 0.75 and 1.0. Mossbauer spectra of [Gd.sub.1-x][Sr.sub.x]Fe[O.sub.3-[Delta]] have been taken at various temperatures ranging from 13 to 800 K. Analysis of Mossbauer spectra for this system demonstrated the existence of the mixed valence states of iron and the coordination state of [Fe.sup.3+] and [Fe.sup.4+] ions. The Neel temperature decreases linearly with Sr concentration, suggesting that the superexchange interaction for Gd-O-Fe link is stronger than that for Sr-O-Fe link.

The crystallogarphic and magnetic characteristics of the spinel phase of ferrimagnetic NixFe1-xCr2S4 were investigated using Mossbauer spectroscopy and x-ray diffraction. The results showed that Ni ions occupied the tetrahedral site and that the valence states of the Fe ions were ferrous in nature. The Neel temperature increased with the Ni concentration, indicating that the superexchange interaction for the Ni-S-Cr link was stronger than that of the Fe-S-Cr link.

The electronic and magnetic characteristics of the magnetic semiconductor NixFe1-xCr2S4 were investigated using Mossbauer analysis. The results showed that quadropole splitting in the sample was not affected by temperature due to the separation of the ground orbital state and the first excited state. The magnetic hyperfine field and the quadropole splitting decreased as the level of Fe ion substitution increased.

The magnetic characteristics of FeRh2Se4 were investigated using x-ray analysis, Mossbauer spectroscopy and superquantum interference device magnetometry. The results showed that the sample was pure monoclinic and site distributions were inverted. The Neel temperature was determined to be 45 K, a value which was in good agreement with theoretical predictions. In addition, it was shown that FeRh2Se4 was a purely antiferromagnetic compound.

The magnetic and electronic properties of Ti[O.sub.2-delta] thin films doped by Fe were examined by x-ray diffraction (XRD), vibrating sample magnetometry (VSM), Hall effect, and conversion electron Mossbauer spectroscopy measurements.The ferromagnetism observed in the [Ti.sub.1-x][Fe.sub.x][O.sub.2-delta] films can be explained in terms of a direct ferromagnetic coupling between two neighboring [Fe.sup.3+] ions through an electron trapped in oxygen vacancy nearby.

The density of carbon nanotubes (CNTs) through in situ NH3 plasma pretreatment is controlled and field emission properties with the density variation are investigated. A uniform emission site was obtained and enhanced emission current due to an increase in the field enhancement factor (beta) with the decrease in the density of CNTs.

A method to fabricate carbon nanotubes (CNT)/conducting polymer composite films for the application of CNTs to field emission displays is reported. A uniform CNT/conducting polypyrrole polymer composite film is obtained.

Morphology of Ni particles and the microstructure of carbon tubules were found to be dependent on the growth temperature. The preferential growth of carbon tubules was observed and explained by the orientation and size of the Ni particle.

Cycloaddition reactions on two representative Si(100)2 X 1 and Si(111)7 X 7 were studied focusing on the asymmetric Si pairs, the asymmetric dimer on Si(100)2 X 1 and the adatom restatom pair on Si(111) 7 X 7, since cycloaddition reactions were found experimentally only on the asymmetric pairs. The experimental observation provided insight into the study of the dependence of a cycloaddition reaction on the symmetry of a Si pair.