Ultrasonic spray pyrolysis for nanoparticles synthesis

This article presents new findings regarding the effects of precursor drop size and precursor concentration on product particle size and morphology in ultrasonic spray pyrolysis. Large precursor drops (diameter > 30 m) generated by ultrasonic atomization at 120 kHz yielded particles with holes due to high solvent evaporation rate, as predicted by the conventional one particle per drop mechanism. Precursor drops 6–9 m in diameter, generated by an ultrasonic nebulizer at 1.65 MHz and 23.5 W electric drive power, yielded uniform spherical particles 90 nm in diameter with proper control of precursor concentration and residence time. Moreover, air-assisted ultrasonic spray pyrolysis at 120 kHz and 2.3 W yielded spherical particles about 70% of which were smaller than those produced by the ultrasonic spray pyrolysis of the 6–9 m precursor drops, despite much larger precursor drop size (28 m peak diameter versus 7 m mean diameter). These particles are much smaller than predicted by the conventional one particle per drop mechanism, suggesting that a gas-to-particle conversion mechanism may also be involved in spray pyrolysis.     

The evaluation of hot-working characteristics of cobalt-based implant alloys

The hot-working characteristics of wrought Co-Ni-Cr-Mo implant alloy during ingot-to-billet conversion were evaluated using a Gleeble-2000A simulator. The hot tensile test at 700–1 320 °C was used to determine the optimum hot-working parameters at a strain rate equivalent to that of conventional press forging to ensure acceptable hot workability. Hot ductility and deformation resistance as a function of temperature can be clearly established. The fracture surfaces of the tensile specimens were examined to correlate them with the hot tensile ductility values at various temperatures. The poor ductility at temperatures above 1300 °C was attributed to the incipient melting of grain boundaries. The effect of temperature and strain rate on the flow-stress behaviour and microstructures were investigated by uniaxial compression testing in the temperature range 900–1200 °C and strain rate, , range of 0.01–10s^–1. The strain-hardening and steady-state behaviour were described from the measured true stress-true strain curves.     

Using Finite-Element Method to Simulate Wave Transformations in Surf Zone

In this study, a finite element method proposed by Hsu et al. in 2003 is extended to develop a numerical model for the simulation of wave transformation in the surf zone. The governing equation is the elliptic mild-slope equation including the energy dissipation of wave breaking. At the open boundaries with varying depth, the reflected waves caused by shoaling are adopted to the radiation boundary conditions. The rationality of the present numerical model is examined through the cases of offshore parallel breakwater problems. The results of calculation are in good agreement with experimental results.     

GaAs-GaAlAs heterostructure single-mode channel-waveguide cutoff modulator and modulator array

A GaAs single-mode channel-waveguide cutoff modulator that utilizes a GaAs-GaAlAs heterostructure and a linear array of such modulators are reported for the first time. We have measured a cutoff voltage as low as 9.0 V and an extinction ratio greater than 20 dB at an optical wavelength of 1.3 μm in a basic modulator that utilized a GaAs-Ga0.93Al0.07As heterostructure with a 0.9 μm thick GaAs epitaxial layer together with a ridge channel 2.5 mm in length and 5.0 μm in width. We have also succeeded in the realization of a high packing density (500 channels/cm) linear array of such cutoff modulators in the same GaAs substrate with equally satisfactory results. An RF bandwidth of 2.5 GHz has also been measured with the elementary modulator of such array. As in the case for LiNbO3substrates, the GaAs-based integrated optic modules that result from integration of such cutoff modulator arrays, microlens arrays, and planar acoustooptic or electrooptic Bragg diffraction grating arrays in a common substrate may be used to perform multiport switching, computing, and RF signal processing.     

A common mutation in the methylenetetrahydrofolate reductase gene (C677T) increases the risk for deep-vein thrombosis in patients with mutant factor V (factor V:Q506)

Hyperhomocysteinemia is a frequent risk factor for deep-vein thrombosis. A common mutation (C677T) in the gene encoding for methylenetetrahydrofolate reductase (MTHFR) is responsible, in the homozygous state, for decreased enzyme activity and mild hyperhomocysteinemia and is associated with increased risk for cardiovascular disease. We studied the prevalence of C677T MTHFR in 77 patients with deep-vein thrombosis and in 154 age- and sex-matched healthy control subjects. In the same individuals, we also evaluated the frequency of the coexistence of C677T MTHFR with mutant factor V:Q506, a common risk factor for deep-vein thrombosis. Sixteen patients (20.8%) and 35 control subjects (22.7%) were homozygous for the C677T MTHFR mutation (odds ratio [OR] = 0.8, 95% confidence interval [CI] = 0.4-2.0). Sixteen patients (20.8%) and 4 control subjects (2.6%) had factor V:Q506; of them, 10 patients and 3 control subjects had isolated factor V:Q506 (adjusted OR = 6.3, 95% CI = 1.6-25.3) and 6 patients and 1 control subject also had C677T MTHFR (adjusted OR = 17.3, 95% CI = 2.0-152.9). The OR for the coexistence of the two mutations was 65% to 75% higher than the expected joint effect calculated by either an additive (OR = 6.0) or multiplicative (OR = 4.4) model. The homozygous C677T mutation of MTHFR per se is not a risk factor for deep-vein thrombosis but increases the risk associated with factor V:Q506. Due to the high prevalence of C677T MTHFR, it is likely that previous studies, which did not look for this mutation, overestimated the relative risk of thrombosis associated with factor V:Q506 alone.     

Percutaneous balloon pericardiotomy for patients with recurrent pericardial effusion: using a novel double-balloon technique with one long and one short balloon

Percutaneous balloon pericardiotomy is effective and less invasive for the treatment of recurrent pericardial effusion. This study suggests that the double-balloon method with 1 longer and 1 shorter balloon is the procedure of choice for percutaneous balloon pericardiotomy.