Production of ordered silicon nanocrystals by low-energy ion sputtering

We report on the production of ordered assemblies of silicon nanostructures by means of irradiation of a Si(100) substrate with 1.2 keV Ar ions at normal incidence. Atomic Force and High-Resolution Transmission Electron microscopies show that the silicon structures are crystalline, display homogeneous height, and spontaneously arrange into short-range hexagonal ordering. Under prolonged irradiation (up to 16 hours) all dot characteristics remain largely unchanged and a small corrugation develops at long wavelengths. We interpret the formation of the dots as a result of an instability due to the sputtering yield dependence on the local surface curvatureComment: 4 two-column pages (revtex4), 3 figures (higher quality copies in the printed jrnl. version

Growth of spheroidal graphite: light versus scanning and transmission electron microscopies

International audienc

Formation of the oxide coating on the titanium surface by multipulse femtosecond laser irradiation

The effect of the femtosecond laser irradiation on the formation of oxide layers on the surface of a commercially pure titanium VT1-0 was studied. The methods of X-ray analysis, scanning electron and transmission electron microscopies were used to study the structural and phase state of oxide layers. As a result of the femtosecond laser irradiation, the porous multi-phase nanocrystalline oxide coating with a thickness of 50 µm is formed on the titanium surfac

Synthesis and characterization of conducting polyaniline nanotubes in the presence of colloidal TiO2 nanoparticles

Conducting polyaniline nanotubes were synthesized by the oxidative polymerization of aniline with ammonium peroxydisulfate in water, in the presence of colloidal TiO2 nanoparticles of an average diameter ~5 nm. Polyaniline-TiO2 nanocomposite has been characterized by the electrical conductivity measurements, thermogravimetric analysis, FTIR spectroscopy, scanning and transmission electron microscopies. The electrical conductivity of synthesized nanocomposite was 1.1 × 10–3 S cm–1, slightly higher than that of pure polyaniline prepared under the same conditions. Polyaniline nanotubes have an outer diameter of 45–230 nm nm, an inner diameter of 15–130 nm, and a length extending from 0.5 to 2.0 μm.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Ultrasound-assisted synthesis of nanostructured LiFePO4/C composite

Poster presented at the Women in Nano Winter School, Kranjska Gora, Slovenia, February 7-9, 200

Increased number of activated microglia in rat spinal cord during early stage of diabetic induction

Background: Diabetic neuropathy is a common chronic complication in diabetes mellitus. Such neuropathy associates with chronic inflammation and immune system activation. Microglia, a type of neuroglia, are involved in the immune system and are found in grey and white matter of the central nervous system, such as the brain and spinal cord. The spinal cord connects the peripheral nervous system and the higher brain centre. Hyperglycaemia during diabetes mellitus has been found to activate and increase number of microglia in the dorsal grey horn or column of the lumbar segments in spinal cord, which release several cytokines in the development of hypersensitivity in diabetic neuropathic pain.Materials and methods: Therefore, in this study, anatomical alterations of rat spinal microglia in all areas (dorsal, intermediate and ventral columns of grey matter and dorsal, lateral and ventral funiculi of white matter) in cervical enlargement, thoracic level and lumbosacral enlargement were observed in early stage of diabetic conditions by using light and transmission electron microscopies.Results: The numbers of microglia in all parts of grey and white matter of all spinal levels significantly increased in the diabetic group. The structures and ultrastructures of microglia in grey and white matter at cervical enlargement, thoracic level and lumbosacral enlargement similarly changed in diabetes. In diabetic rats, microglia became hypertrophied with a pale nucleus. Moreover, short fragments of rough endoplasmic reticulum, elevated numbers of lysosomes and numerous actin filaments in the cytoplasm were examined. Microglial phagocytosis of myelin and axonal debris were also observed. In this investigation, the morphology of spinal microglia during short-term diabetes became activated during hyperglycaemia. Conclusions: It is suggested that these changes may be involved in the development of diabetic neuropathic pain in the spinal cord

Spin state dependence of electrical conductivity of spin crossover materials

We studied the spin state dependence of the electrical conductivity of the spin crossover compound [Fe(Htrz)2(trz)](BF4) (Htrz = 1H-1,2,4-triazole) by means of dc electrical measurements. The low spin state is characterized by higher conductance and lower thermal activation energy of the conductivity, when compared to the high spin state

Nanosized carbon forms in the processes of pressure–temperature-induced transformations of hydrocarbons

The products of thermal conversions of naphthalene, anthracene, pentacene, perylene, and coronene at 8 GPa in the temperature range up to 1300 C have been studied by scanning electron and high-resolution transmission electron microscopies. As a result, it has been established that various nanometer-sized carbon species (spherical and coalesced two-core onion-like carbon particles, faceted polyhedral particles, graphitic ribbons, graphitic folds, and nanocrystalline diamonds) are present in the conversion products together with micron-sized crystallites of graphite and diamond. 2006 Elsevier Ltd. All rights reserved

Aging Characteristics and Weld-solidified Structure in Al-Zn-Mg Alloy Welds

The aging characteristics and the weld-solidified structure of weld Al-Zn-Mg alloys, and the effects of grain and dendrite cell sizes on the aging characteristics of rapidly solidified Al-Zn-Mg alloys were examined by hardness measurements, the X-ray small-angle scattering and by optical- and transmission electron microscopies. Differences in macrostructures in weld Al-Zn-Mg alloys have no effect on their aging characteristics. Differences between microstructures of weld alloys and those of heat-affected zones in the alloy welds affect their aging characteristics. Sub-grains in the weld metals of Al-Zn-Mg alloy welds decrease their age-hardening capacities at 80°C, but increase them at 150°C. These results are discussed in terms of solute segregations and preferred precipitation η′ phases at sub-grain boundaries or on dislocations in the weld metals of Al-Zn-Mg alloy welds

A New Method for Investigation of the Hair Shaft: Hard X-Ray Microscopy with a 90-nm Spatial Resolution

Various methods have been used to investigate the hair shaft. In the ultrastructural hair field, scanning and transmission electron microscopies are widely used investigative methods, but they have some technical limitations. Recently, X-ray microscopes with sub-micron spatial resolution have emerged as useful instruments because they offer a unique opportunity to observe the interior of an undamaged sample in greater detail. In this report, we examined damaged hair shaft tips using hard X-ray microscopy with a 90 nm spatial resolution. The results of this study suggest that hard X-ray microscopy is an alternative investigative method for hair morphology studies