Characterization of titanium-boron binary oxides and their photocatalytic activity for stoichiometric decomposition of water

A titanium-boron binary oxide has been prepared by sol–gel method and used as a photocatalyst for the decomposition of water. The structure of titanium oxide species in the Ti/B binary oxide was amorphous before and crystal after calcination in O₂, while the boron oxide species maintained its amorphous state. With increasing calcination temperature, the crystalline structure of titanium oxides changed from an anatase phase to a rutile phase. Pt-loaded Ti/B photocatalysts decomposed water stoichiometrically in aqueous suspension system. Their photocatalytic activity decreased markedly with increase in the calcination temperature, indicating that the photocatalytic activity of the Ti/B binary oxide was strongly dependent on the crystal phase of the titanium oxide in the Ti/B binary oxide. A remarkable yield in the reaction of water decomposition was obtained when Na₂CO₃ was added in the Pt-loaded Ti/B binary oxide suspension.     

Skyline index for time series data

We have developed a new indexing strategy that helps overcome the curse of dimensionality for time series data. Our proposed approach, called skyline index, adopts new skyline bounding regions (SBR) to approximate and represent a group of time series data according to their collective shape. Skyline bounding regions allow us to define a distance function that tightly lower bounds the distance between a query and a group of time series data. In an extensive performance study, we investigate the impact of different distance functions by various dimensionality reduction and indexing techniques on the performance of similarity search, including index pages accessed, data objects fetched, and overall query processing time. In addition, we show that, for k-nearest neighbor queries, the proposed skyline index approach can be coupled with the state of the art dimensionality reduction techniques such as adaptive piecewise constant approximation (APCA) and improve its performance by up to a factor of 3.     

Study on the interfacial properties of three‐dimensionally arranged glass fiber/epoxy resin model composites

The effect of interfiber distance on the interfacial properties in three‐dimensional multi‐E‐glass fiber/epoxy resin composites has been investigated using fragmentation test. In additions, the effect of the fiber surface treatment on the interfacial properties has been studied. The interfacial shear strength decreased with the decreasing the interfiber distance at the range of under 50 μm and the extent of the decreasing was more serious as the increasing of the number of adjacent fiber. This is probably due to the fact that the interface between the fiber and the resin was damaged by the adjacent fiber breaks and the damage increased with closing the interfiber spacing and the number of adjacent fiber. It was found that the interfacial shear strengths saturated when the interfiber distance was over 50 μm, the ones were saturated regardless of fiber surface treatment and the ones were in close agreement with those of the single fiber fragmentation test. Finally, the interfacial shear strength evaluated using three‐dimensional fragmentation tests are shown as real values in‐site regardless of fiber surface treatment, interfiber distance and existing of matrix cracks. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A novel lactic acid bacterium for the production of high purity L-lactic acid, Lactobacillus paracasei subsp. paracasei CHB2121

Fermentation-derived lactic acid has several potential industrial uses as an intermediate carbon chemical and a raw material for biodegradable polymer. We therefore undertook the identification of a novel bacterial strain that is capable of producing high concentrations of lactic acid and has potential commercial applications. A novel L(+)-lactic acid producing bacterium, Lactobacillus paracasei subsp. paracasei CHB2121 was isolated from soil obtained near an ethanol production factory and identified by 16S rRNA gene sequence analysis and characterization using an API 50 CHL kit. L. paracasei subsp. paracasei CHB2121 efficiently produced 192 g/L lactic acid from medium containing 200 g/L of glucose, with 3.99 g/(L·h) productivity, and 0.96 g/g yield. In addition, the optical purity of the produced lactic acid was estimated to be 96.6% L(+)-lactic acid. The newly identified L. paracasei subsp. paracasei CHB2121 efficiently produces high concentrations of lactic acid, and may be suitable for use in the industrial production of lactic acid.     

Evolution of microstructure and tensile strength of rapidly solidified Al-4.7 pct Zn-2.5 pct Mg-0.25 pct Zr-X wt pct Mn alloys

Analytical transmission electron microscopy and thermal analysis of as-extruded Al-4.7 pct Zn-2.5 pct Mg-0.2 pct Zr-X wt pct Mn alloys, with Mn contents ranging from 0.5 to 2.5 wt pct, were carried out to elucidate the microstructural change and accompanying mechanical properties during subsequent heat treatments. The as-extruded alloy was fabricated from rapidly solidified powder and consisted of a fine, metastable manganese dispersoid and the ternary eutectic T phase (Al₂Mg₃Zn₃). Solution heat treatment resulted in the formation of the stable Al₆Mn phase and complete dissolution of the T phase. Formation of stable Al₆Mn was made by two routes: by phase transition from metastable Mn dispersoids which already existed, and from the supersaturated solid solution by homogeneous nucleation. The density of the Al₆Mn phase increased with the addition of manganese, while the shape and average size remained unchanged. A significant increase in the hardness was observed to coincide with the formation of the Al₆Mn phase. Similarly, the tensile strength increased further after the aging treatment, and the increment was constant over the content of Mn in the alloy, which was explained by the contribution from the same amount of precipitates, MgZn₂. Results of thermal analysis indicated that the dissolution of the T phase started near 180 °C and that formation of Al₆Mn occurred at about 400 °C, suggesting that further enhancement of strength is possible with the modification of the heat-treatment schedule.     

Forced assembly and mixing of melts via planar polymer micro-mixing

The ability to force immiscible polymers into specific, targeted structures would enable the generation of blends with tailored performance by exploiting the intimate relationship between structure and blend properties. Here we present a strategy for the forced assembly of immiscible polymers into targeted structures via development of a planar polymer micro-mixer (PPMM). The PPMM drives streams of molten polymer through mixing chambers, which are fabricated from metal shims that contain flow channels. By stacking the shims, complex 3D mixing flows can be generated. The advantages of this mixing technology include sample sizes significantly less than traditional micro-mixers (<100 mg), simple reconfiguration of the flow geometry, and optical access to the flow. Most significantly, it offers a path towards targeted blend structures rather than the more typical domain/matrix or random co-continuous ones. We observe the creation of multi-layers and coaxial cylinders in the first five mixing units, beyond that that interfacial tension and non-ideal flow tends to force the creation of mixed domain/matrix structures. The PPMM, along with the recently developed multi-sample micro-slit rheometer, is expected to be a key component of the “polymer processing lab-on-a-chip”.     

X‐Band Phased Array Antenna Using Ferroelectric (Ba,Sr)TiO3 Coplanar Waveguide Phase Shifter

A phased array antenna was fabricated using four‐element ferroelectric phase shifters with a coplanar waveguide (CPW) transmission line structure based on a Ba0.6Sr0.4TiO3(BST)/MgO structure. Epitaxial BST films were deposited on MgO (001) substrates by pulsed laser deposition. To attain the large differential phase shift and small losses for a ferroelectric CPW phase shifter, an impedance‐matching‐part adding technique between the effective transmission line and connecting cable was used. The return loss and insertion loss for this technique‐adapted BST CPW device were improved with respect to those for a normal BST CPW device. For an X‐band phased array antenna system consisting of ferroelectric BST CPW phase shifters, power divider, dc block, patch antenna, and programmed dc power, the steering beam could be tilted by 15° in either direction.     

Stopless flow injection in asymmetrical flow field-flow fractionation using a frit inlet

Stopless flow operation of asymmetrical flow field-flow fractionation (FFF) has been achieved by introducing a hydrodynamic relaxation method using a frit inlet. By using frit inlet injection, a focusing process which has been an essential part of runs at the asymmetrical flow FFF system can be completely avoided. Band broadening of an initial sample zone during hydrodynamic relaxation is discussed with equations related to the ratio of two inlet flow rates. For the successful achievement of particle relaxation and separation, it is necessary to apply a small ratio of sample inlet to frit inlet flow rate. Experimental results are reported for the evaluation of the system efficiency at various levels of hydrodynamic relaxation and for both normal and steric/hyperlayer modes of FFF runs using latex standards. Most importantly, it is shown that a high resolution and a high-speed separation of submicrometer-sized latex mixtures can be accomplished in asymmetrical flow FFF without using the conventional focusing relaxation process.     

Use of a genetic algorithm in the search for a near-optimal shielding design

An optimization method based on genetic algorithm (GA), which is referred as MACroscopic Near-Optimal Shielding design (MACNOS), is proposed for the search for an optimal radiation shield configuration subject to a given set of constraints. In MACNOS, a GA is used to search for the optimal shielding design and the penalty strategy is employed to deal with the constraints. In order to confirm its capability to search for the optimal shielding design, MACNOS is applied for solving a simple problem with regard to radiation shielding optimization of a hypothetical spaceship reactor. The application shows that, keeping the constraints satisfied, MACNOS is able to seek for the shielding design that minimizes the total weight by changing the thickness and the material of the shield. Therefore, it is expected that MACNOS is potentially useful in the search for the optimal design configuration in the conceptual design phase, where the selection of the shielding material and the estimate of the thickness are necessary.     

Cost-Effective Zero-Voltage and Zero-Current Switching Current-Fed Energy-Recovery Display Driver for ac Plasma Display Panel

A new cost-effective zero-voltage and zero-current switching (ZVZCS) current-fed energy-recovery display driver for a plasma display panel (PDP) is proposed. It features a simpler structure, less mass, and lower cost of production. Furthermore, since all power switches are turned on or off under zero-voltage or zero-current switching, it has several favorable advantages such as an improved electromagnetic interference (EMI), low switching losses, and reduced burden on the cooling system. Particularly, since the current source built in the inductor can compensate the large gas-discharge current, main inverter switches have the reduced current stress and turn-on timing margin. Therefore, the undesirable voltage notch problem caused by the improperly controlled gate signal can be solved, which enables the panel to light at lower voltage such as 143 V compared with about 165 V of the prior circuit. To confirm the operation, validity, and features of the proposed circuit, experimental results from a prototype built with 6-in test PDP are presented.