Structural origin of light emission in germanium quantum dots.

We used a combination of optically-detected x-ray absorption spectroscopy with molecular dynamics simulations to explore the origins of light emission in small (5 nm to 9 nm) Ge nanoparticles. Two sets of nanoparticles were studied, with oxygen and hydrogen terminated surfaces. We show that optically-detected x-ray absorption spectroscopy shows sufficient sensitivity to reveal the different origins of light emission in these two sets of samples. We found that in oxygen terminated nanoparticles its the oxide-rich regions that are responsible for the light emission. In hydrogen terminated nanoparticles we established that structurally disordered Ge regions contribute to the luminescence. Using a combination of molecular dynamics simulations and optically-detected x-ray absorption spectroscopy we show that these disordered regions correspond to the disordered layer a few Šthick at the surface of the simulated nanoparticle.

Large-scale, reliable and robust SERS-active nanowire substrates prepared using porous alumina templates.

nanowire arrays for surface-enhanced Raman scattering applications. These nanowire films were synthesized via electrodeposition using porous alumina templates of varying order, thickness and pore diameters. Mechanical polishing has been shown to be a very effective method to prepare nanowire arrays with monodisperse length over comprehensively large dimensions. On the other hand, a convenient synthesis route has been suggested that allows the formation of nanoparticle rrays using very thin and/or large area porous alumina films. It is reckoned that even films with the smallest obtainable pore sizes can be utilized to prepare large area, fine nanoparticle arrays. Such arrays may also find use in other areas, such as solar cells and electrochemistry. Preliminary Raman experiments indicated that the nanowire/nanoparticle arrays are indeed surface-enhanced Raman scattering-active. Finally, the potentials offered by the reported processing methods for fabricating substrates with predictable and high Raman amplifications are discussed.

Pressure-induced crossover between diffusive and displacive mechanisms of phase transitions in single-crystalline alpha-GeO2.

We present the first example of the phase transition occurring via the different kinetic mechanisms, displacive or diffusive, competing with each other in quartz-like alpha-GeO2 single crystals. Upon room-pressure heating, alpha-GeO2 transforms to the rutile-type phase (the alpha-->r transition) via the diffusive mechanism. With increase of the treatment pressure the diffusive mode of the temperature-induced alpha-->r transition is substituted at approximately 4 GPa by a displacive-like mode, and then at approximately 6 GPa the transition type changes from the alpha-->r sequence to a displacive martensitic-like transition to a distorted rutile-like phase (alpha-->r'. A crossover between diffusive and displacive transition modes suggests a new way to control the meso- and nanometer-scale morphology of high-pressure phases.

In situ EXAFS, X-ray diffraction and photoluminescence for high-pressure studies.

A new facility for simultaneous extended X-ray absorption of fine structure (EXAFS), X-ray diffraction and photoluminescence measurements under high pressures has been developed for use on station 9.3 at the Daresbury Laboratory Synchrotron Radiation Source. This high-pressure facility can be used at any suitable beamline at a synchrotron source. Full remote operation of the rig allows simultaneous collection of optical and structural data while varying the pressure. The set-up is very flexible and can be tailored for a particular experiment, such as time- or temperature-dependent measurements. A new approach to the collection of high-pressure EXAFS data is also presented. The approach significantly shortens the experimental times and allows a dramatic increase in the quality of EXAFS data collected. It also opens up the possibility for EXAFS data collection at any pressure which can be generated using a diamond cell. The high quality of data collected is demonstrated with a GaN case study. Particular attention will be paid to the use of energy-dispersive EXAFS and quick-scanning EXAFS techniques under pressure.

[Extracorporeal shockwave lithotripsy on the Sonolith-3000 apparatus]. / Distantsionnaia udarno-volnovaia litotripsiia na apparate "Sonolit-3000".

The authors observed 812 patients with nephrolithiasis who underwent 876 sessions of shock-wave lithotripsy on Sonolith-3000 lithotriptor supplied with an ultrasonic system of the stone localization. The size of nephroliths ranged from 0.7 to 4.2 cm. Large-size nephroliths required repeated sessions and pretreatment establishment of the stent. The procedure proceeded without anesthesia. Subsequent renal colic was reported in 126 (15.5%), an exacerbation of pyelonephritis in 45 (5.5%), subcapsular hematoma in 4 (0.5%) of the patients. 790 patients showed clinical response (97.3%), with a complete destruction of the stone in 446 (54.9%) and partial one in 344 (42.4%) cases. 27 subjects were treated in outpatient setting. According to the authors, lithotripsy is contraindicated in urinary tract obstruction below the stone, renal failure, chronic pyelonephritis in the active phase of inflammation, marked impairment of cardiac rhythm.