HAADF-STEM study on the early stage of precipitation in aged Al-Ag alloys

We report on the structure of Ag precipitates in aged Al-Ag alloys using transmission electron microscopy and high-angle annular detector darkfield scanning transmission electron microscopy (HAADF-STEM). Irregularly shaped small Ag particles of 1-2 nm dominate the alloy annealed at 140 degrees C for 10 h. These particles are present also within large precipitates (10-50 nm), which are often characterized by their {100} and {110} facets. In addition, atomic-resolution HAADF-STEM images revealed that Ag atoms tend to form {111} planar clusters, which criss-cross a colony of the irregularly shaped small Ag precipitates.     

C60(Cg) and C70(g): A computational study of the pressure and temperature dependence of their populations

Equilibrium mixtures of pure carbon gas-phase aggregates, C_n(g). are treated combining all available observational as well as computational thermodynamical data for n = 1, 2, 3, 4, 5, 60 and 70. A considerable sensitivity to temperature and pressure is pointed out, showing that there are both regions of a higher relative population of C₆₀(g) as well as of C₇₀(g). There can be significant competition between the formation of small and large clusters. Relations between the full-equilibrium situation (i.e., including graphite), gas-phase equilibrium, and the nonequilibrium situation are discussed.     

An Oxygen-Effervescent Aluminate Glass

A foaming-agent-free aluminate glass of the composition 59CaO·7MgO·27Al₂O₃·7SiO₂ (mol%) exhibited marked effervescence on heating the as quenched glass to near its softening temperature. Numerous bubbles evolve over the entire glass. Their radii are nearly constant (50 μm) and depend on heat-treatment conditions. Their maximum volume goes up to ∼ 10 vol%. The bubbles consist solely of oxygen gas and pressure is ∼ 130 kPa (1.3 atm) at the softening temperature.     

Nanoinjector for capillary electrophoresis and capillary electrochromatography

A rotary valve nanoinjector was devised for use in capillary electrophoresis (CE) and capillary electrochromatography (CEC). A fused-silica capillary tip was inserted in a small through-hole in the rotor. The narrow and short capillary tip, with an inner volume of 6-24 nL, was embedded in the hole using epoxy resin. The injection volume was confirmed chromatographically by comparing the peak areas obtained with the nanoinjector to those of a conventional injector. In addition, both the rotor and stator of the injector were made of a nonconducting material, polyimide resin, to be utilized for CE and CEC. The application of the nanoinjector for CE was demonstrated.     

Monte Carlo prediction of near-infrared light propagation in realistic adult and neonatal head models

In near-infrared spectroscopy and imaging, the sensitivity of the detected signal to brain activation and the volume of interrogated tissue are clinically important. Light propagation in adult and neonatal heads is strongly affected by the presence of a low-scattering cerebrospinal fluid layer. The effect of the heterogeneous structure of the head on light propagation in the adult brain is likely to be different from that in the neonatal brain because the thickness of the superficial tissues and the optical properties of the brain of the neonatal head are quite different from those of the adult head. In this study, light propagation in the two-dimensional realistic adult and neonatal head models, whose geometries are generated from a magnetic resonance imaging scan of the human heads, is predicted by Monte Carlo simulation. The sandwich structure, which is a low-scattering cerebrospinal fluid layer held between the high-scattering skull and gray matter, strongly affects light propagation in the brain of the adult head. The sensitivity of the absorption change in the gray matter is improved; however, the intensely sensitive region is confined to the shallow region of the gray matter. The high absorption of the neonatal brain causes a similar effect on light propagation in the head. The intensely sensitive region in the neonatal brain is confined to the gray matter; however, the spatial sensitivity profile penetrates into the deeper region of the white matter.     

Influence of perfusion depth on laser Doppler flow measurements with large source-detector spacing

Laser Doppler flowmetry with a large source-detector spacing has been applied to measure blood perfusion in the deeper regions of tissue. The influence of the depth of perfusion on the Doppler spectrum for the large source-detector spacing is likely to be different from that for the conventional laser Doppler instruments with small source-detector spacing. In this study, the light propagation in a tissue model with a blood perfusion layer is predicted by the Monte Carlo simulation to discuss the influence of the depth of perfusion, blood volume, and source-detector spacing on the spectrum of the Doppler signal detected with large source-detector spacing. The influence of the depth of perfusion on the Doppler spectrum for the large source-detector spacing is different from that for the conventional laser Doppler instruments with small source-detector spacing, although the influence of source-detector spacing and blood volume on the Doppler spectrum for large source-detector spacing is almost the same as that for the conventional laser Doppler instruments. The influence of the depth of the perfusion on the Doppler spectrum depends on the path length that the detected light travels at different depths.     

Prediction of air coil performance under partially wet and totally wet cooling conditions using equivalent dry-bulb temperature method

This paper mainly deals with the cooling and dehumidifying performance of air coils used in refrigeration and air-conditioning systems. A new method, equivalent dry-bulb temperature (EDT) method, is proposed for calculating the heat and mass transfer and for predicting the cooling modes (totally wet, partially wet, and totally dry) of moist air over the coil surface. A numeric model is further developed and validated with the experimental data of plain fin air coils. The deviation in both the cooling capacity and the vapor condensate estimated by the model is within the range of ±10%, and the prediction for the cooling modes of moist air over the coil surfaces is fairly exact.     

Collagen of octopus Callistoctopus arakawai arm

In an investigation into making more effective use of underutilized fisheries resources, collagen was prepared from Callistoctopus arakawai arm. The arm was only slightly solubilized in acetic acid but on digestion with 10% pepsin (w/v), pepsin-solubilized collagen (PSC) was successfully produced. The PSC obtained was a pinkish fibre. The yields of acid-solubilized collagen (ASC) and PSC were about 10.4 and 62.9%, respectively. The PSC has a chain composition of α1α2α3 heterotrimer, different from Octopus vulgaris skin. The denaturation temperature of this collagen was lower than porcine collagen. This report indicates that C. arakawai has potential for supplementing the skin of land vertebrates as a source of collagen.     

Dispersing behaviour of droplets in suspension polymerization of styrene in a loop reactor

Suspension polymerization of styrene was performed using a loop reactor. The dispersing behaviour of the droplets in the course of the reaction was observed. The mean droplet diameter was determined by the energy level at the impeller region. Moreover, the final particle size distribution and mean particle size were also determined after an elapsed time of 1-2 hrs. An expression which correlated the final mean particle size with the operating conditions, such as the mixing conditions at the impeller region and the initial physical properties of the suspension system, was derived. The deposition of polymers on the reactor wall was found to be prevented due to the high fluid velocity.