Ultrasonic thin-walled tube wave structure for sensing devices

Theoretical and experimental investigations of thin-walled tube acoustic wave devices for gravimetric sensing applications are presented. Integrated sensor configurations have been demonstrated by employing a sol-gel processed thin piezoelectric lead zirconate titanate (PZT) film. This was coated coaxially on stainless steel tubes and interdigital transducers (IDT) fabricated as the transmitter and receiver on the curved tube surfaces. We have observed tube waves along both the axial and circumferential directions between 1 and 6.6 MHz. We have also analyzed the mass sensitivities of different modes propagating along the tubes and shown that high mass sensitivity can be achieved by keeping the tube wall thin     

Synthesis and properties of poly(amide–imide)s based on N,N′‐bis(4‐carboxyphenyl)‐4,4′‐oxydiphthalimide,p‐aminobenzoic acid and various aromatic diamines

A new diimide–diacid monomer, N,N′‐bis(4‐carboxyphenyl)‐4,4′‐oxydiphthalimide (I), was prepared by azeotropic condensation of 4,4′‐oxydiphthalic anhydride (ODPA) and p‐aminobenzoic acid (p‐ABA) at a 1:2 molar ratio in a polar solvent mixed with toluene. A series of poly(amide–imide)s (PAI, III_a–m) was synthesized from the diimide–diacid I (or I′, diacid chloride of I) and various aromatic diamines by direct polycondensation (or low temperature polycondensation) using triphenyl phosphite and pyridine as condensing agents. It was found that only III_k–m having a meta‐structure at two terminals of the diamine could afford good quality, creasable films by solution‐casting; other PAIs III using diamine with para‐linkage at terminals were insoluble and crystalline; though III_g–i contained the soluble group of the diamine moieties, their solvent‐cast films were brittle. In order to improve their to solubility and film quality, copoly(amide–imide)s (Co‐PAIs) based on I and mixtures of p‐ABA and aromatic diamines were synthesized. When on equimolar of p‐ABA (m = 1) was mixed, most of Co‐PAIs IV had improved solubility and high inherent viscosities in the range 0.9–1.5 dl g^?1; however, their films were still brittle. With m = 3, series V was obtained, and all members exhibited high toughness. The solubility, film‐forming ability, crystallinity, and thermal properties of the resultant poly(amide–imide)s were investigated. © 2002 Society of Chemical Industry     

Methionine restriction up‐regulates the expression of the pi class of glutathione S‐transferase partially via the extracellular signal‐regulated kinase‐activator protein‐1 signaling pathway initiated by glutathione depletion

Understanding the molecular events underlying gene regulation by amino acids has attracted increasing attention. Here, we explored whether the mechanism by which methionine restriction affects the expression of the π class of glutathione S‐transferase (GSTP) is related to oxidative stress initiated by glutathione (GSH) depletion. Rat primary hepatocytes were cultured in an L‐15‐based medium in the absence or presence of 200 μM L ‐buthionine sulfoximine (BSO) or in a methionine‐restricted L‐15 medium supplemented with 20 μM L ‐methionine up to 72 h. BSO and methionine restriction time‐dependently induced GSTP mRNA and protein expression in a similar pattern accompanied by a decrease in the cellular GSH level. The phosphorylation of extracellular signal‐regulated kinase (ERK), but not of c‐Jun NH₂‐terminal kinase and p38, was stimulated by methionine restriction and BSO. Electromobility gel shift assay showed that the DNA‐binding activity of nuclear activator protein‐1 (AP‐1) increased in cells exposed to methionine restriction or BSO. With the ERK inhibitor FR180204, AP‐1 activation and GSTP expression were abolished. Moreover, the induction of GSTP by methionine restriction and BSO was reversed by GSH monoethyl ester and N‐acetylcysteine. Our results suggest that methionine restriction up‐regulates GSTP gene expression, which appears to be initiated by the ERK‐AP‐1 signaling pathway through GSH depletion in rat hepatocytes.     

LTPS circuit integration for system‐on‐glass LCDs

Abstract— A 3.5‐in. QVGA‐formatted driving‐circuit fully integrated LCD has been developed using low‐temperature poly‐Si (LTPS) technology. This display module, in which no external ICs are required, integrates all the driving circuits for a six‐bit RGB digital interface with an LTPS device called a “FASt LDD TFT” and achieves a high‐quality image, narrow frame width, and low power consumption. The LTPS process, device, and circuit technologies developed for system‐on‐glass LCD discussed. The development phase of LTPS circuit integration for system‐on‐glass LCDs is also reviewed.     

Preparation of superhydrophobic silica‐based films by using polyethylene glycol and tetraethoxysilane

Preparation of superhydrophobic silica‐based films via sol‐gel process by adding polyethylene glycol (PEG4000) in the silica sol precursor solution has been developed. The casting films were prepared by casting the above solution on the glass and adding poor solvent on it or not. Surface roughness of the films was obtained by removing polymer from the films at high temperature. Then, the hydrophobic group on the surfaces was obtained by reaction with hexamethyldisilazane (HMDS). Characteristic properties of the as‐prepared surface of the films were analyzed by contact angle measurement, scanning electron microscopy (SEM), atomic force microscope (AFM), Fourier transform infrared (FT‐IR) spectrophotometer, and X‐ray photoelectron spectrometer (XPS). The results showed that the contact angles of the films were varied with the PEG weight fraction of the films, the solvent for the PEG solution, the reaction temperature and time, and adding poor solvent (n‐hexane) or not. However, the surface roughness has been controlled by adjusting the experimental parameters during the early period. The contact angle of the film that prepared by spraying the poor solvent (n‐hexane) onto each coating layer for four times after casting process was greater than 150°. It was difficult to obtain superhydrophobic surface without adding n‐hexane onto any coating layer in this system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Enhanced Emission of (In,Ga) Nitride Nanowires Embedded with Self‐Assembled Quantum Dots

We report the structure and emission properties of ternary (In,Ga)N nanowires (NWs) embedded with self‐assembled quantum dots (SAQDs). InGaN NWs are fabricated by the reaction of In, Ga and NH₃ via a vapor–liquid–solid (VLS) mechanism, using Au as the catalyst. By simply varying the growth temperature, In‐rich or Ga‐rich ternary NWs have been produced. X‐ray diffraction, Raman studies and transmission electron microscopy reveal a phase‐separated microstructure wherein the isovalent heteroatoms are self‐aggregated, forming SAQDs embedded in NWs. The SAQDs are observed to dominate the emission behavior of both In‐rich and Ga‐rich NWs. Temperature‐dependent photoluminescence (PL) measurements indicate relaxation of excited electrons from the matrix of the Ga‐rich NWs to their embedded SAQDs. A multi‐level band schema is proposed for the case of In‐rich NWs, which showed an anomalous enhancement in the PL peak intensity with increasing temperature accompanies with red shift in its peak position.     

Inside Vertical-Cavity Surface-Emitting Lasers: Extracting the Refractive Index From Spatial-Spectral Mode Images

We present a method to extract the internal effective refractive index of a vertical-cavity surface-emitting laser (VCSEL) from its transverse mode images. High spatial and spectral resolution mode images of an oxide-guided VCSEL were obtained using an etalon filter and an imaging spectrometer. The refractive index and the oxide radius were extracted from the field intensity distribution and the spectral wavelength of the laser modes. The procedure was repeated at two different currents and both gave a refractive index step of 0.046 plusmn 0.006 with a 14.1-mum oxide diameter. With several degrees of freedom for error available in the refractive index extraction, this method may be extended to ion-implanted, photonic crystal, and noncircular devices     

Stability analyses of group decision making

The importance of multicriteria models in a group decision making is increasingly being emphasized by researchers. One of the most significant of these models is the analytic hierarchy process (AHP). Through the AHP, decision makers are able to conduct a series of pairwise comparisons on pairs of criteria and priority indices can thereby be derived. However, the judgmental process can often be subjective as researchers have not put adequate emphasis on the stability and reliability of group weights observed through the process.

This paper develops a method of replication coupled with the use of the quality confidence intervals in order to generate invigorating debates on a particular issue before weight assignments are made. The replicated assignments are used to determine the group's priority indices. The aim is to enhance the ability of decision makers to make the same decisions when provided with similar environmental conditions. Ultimately, this will provide greater reliability to the derived outcomes. Obviously, the use of multicriteria modelling in subjective assessments would be meaningless if the decisions made were not consistent under the same conditions. In other words, these models would provide no guidance or benefit to decision makers.

In the paper, two case studies relating to the ranking of factors for selection of advanced technologies and issues for achieving competitiveness are analyzed utilizing an experimental group. Paired t-tests show that there are no differences between the rankings observed for the three replications for each respective case for almost all the criteria. Thus, the procedure provided here offers utility in group decision making.