Selective and nonselective wet etching of Zn0.9Mg0.1O/ZnO

Wet etch rates at 25°C for Zn_0.9Mg_0.1O grown on sapphire substrates by pulsed laser deposition (PLD) were in the range 300–1100 nm · min⁻¹ with HCl/H₂O (5×10⁻³−2×10⁻² M) and 120–300 nm · min⁻¹ with H₃PO₄/H₂O (5×10⁻³−2×10⁻² M). Both of these dilute mixtures exhibited diffusion-limited etching, with thermal activation energies of 2–3 kCal · mol⁻¹. By sharp contrast, the etch rates for ZnO also grown on sapphire by PLD were much slower in similar solutions, with rates of 1.2–50 nm · min⁻¹ in HCl/H₂O (0.01–1.2 M) and 12–54 nm · min⁻¹ in H₃PO₄/H₂O (0.02–0.15 M). The etching was reaction limited over the temperature range 25–75°C, with activation energies close to 6 kCal · mol⁻¹. The resulting selectivity of Zn_0.9Mg_0.1O over ZnO can be a high as ∼400 with HCl and ∼30 with H₃PO₄.     

Structural properties of 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 relaxor ferroelectric thin films on SrRuO3 conducting oxides

Coating of 0.65Pb(Mg_1/3Nb_2/3)O₃–0.35PbTiO₃ (PMN–PT) relaxor ferroelectrics by a sol–gel method is followed by growth of epitaxial SrRuO₃ (SRO) metallic oxide electrodes on SrTiO₃ (STO) single-crystal substrate by pulsed laser deposition. High-quality PMN–PT films on SRO with preferred growth orientation were successfully fabricated by controlling the operation parameters. Structural properties of relaxor ferroelectric PMN–PT thin films on SRO/STO substrates have been studied by X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM). In-plane and out-of-plane alignments of the heterostructure are confirmed and the structural twinning of the materials are also revealed.     

Microstructural investigation of long-term degradation mechanisms in GFRP dowel bars for jointed concrete pavement

Steel dowel bar is used to transfer loads in concrete pavement slab. However, once the steel dowel bar corrodes, it may cause faults, such as joint freezing in concrete pavement, level differences resulting from spalling or decreased efficiency of load transfer, etc., which are the same problems experienced by typical reinforcing steel. This study evaluated the applicability of glass fiber-reinforced polymer (GFRP) dowel bar as a substitute for steel dowel bar. A microstructural analysis was conducted to examine the decrease in durability of GFRP dowel bar exposed to deterioration environments. To analyze the deterioration mechanism of GFRP dowel bar, scanning electron microscopy was employed and the porosity was measured by the gas absorption method. It was concluded that the longer the GFRP dowel bar was exposed to deterioration environments, the more the interlaminar shear stress decreased. This result was validated by the microstructural analysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Responses of somatostatin, beta-endorphin and dynorphin A to a glucose load in two groups of women with polycystic ovarian syndrome

Since the late 1980s, the eight-component model of the comprehensive school health program (CSHP), has been adopted widely in the United States and internationally. While it is acknowledged that the eight program elements should be delivered in a coordinated, interactive manner, numerous issues regarding how this integration best can be achieved, including who at the school level should have this responsibility and how the eight components relate conceptually and logistically, have not been addressed adequately. In essence, a CSHP transforms several solo performers into an orchestra. This article proposes the school health coordinator as an essential element in the eight-component model of the CSHP--the maestro, without whom there can be no symphony. The coordinator's principal responsibilities include administration, integration of personnel and programs, evaluation, and direct intervention. Three program elements--staff wellness, healthy environment, and community/family involvement--are subsumed within the coordinator's role, effectively reducing the number of program elements from eight to five. Potential benefits in addition to issues regarding feasibility of the SHC, are discussed and studies examining the effectiveness of the SHC model are recommended.     

Ahch, the mouse homologue of DAX1: cloning, characterization and synteny with GyK, the glycerol kinase locus

We cloned the murine full-length cDNA encoding Ahch, the mouse homologue of DAX1 (DSS-AHC Region on Human X Chromosome, Gene1) which is the gene responsible for human X-linked adrenal hypoplasia congenita (AHC) and hypogonadotropic hypogonadism (HH). Sequence analysis revealed that the murine and human cDNAs have 65% aa identity and 75% aa similarity overall. The cysteine residues in the putative DNA binding domain, which may interact with Zn2+ ions to form zinc fingers, are 100% conserved between the two species, indicating that the novel zinc-finger structures in DAX1 may be functional. In addition, mouse interspecific backcrosses show that the Ahch gene is closely linked to the glycerol kinase locus, GyK, on the mouse X chromosome, indicating that the order of the loci is conserved in this syntenic region between mouse and human.     

Integrated modelling under uncertainty in watershed-level assessment and management.

Uncertainty in water quality model predictions is inevitably high due to natural stochasticity, model uncertainty, and parameter uncertainty. An integrated modelling system (modified-BASINS) under uncertainty is described and demonstrated for use in receiving-water quality prediction and watershed management. A Monte Carlo simulation was used to investigate the effect of various uncertainty types on output prediction. Without pollution control measures in the watershed, the concentrations of total nitrogen (T-N) and total phosphorus (T-P) in the Hwaong Reservoir, considering three uncertainty types, would be less than about 4.4 and 0.23 mg L(-1), respectively, in 2012, with 90% confidence. The effects of two watershed management practices, wastewater treatment plants (WWTP) and constructed wetlands (WETLAND), were evaluated. The combined scenario (WWTP + WETLAND) was the most effective at improving reservoir water quality, bringing concentrations of T-N and T-P in the Hwaong Reservoir to less than 3.4 and 0.14 mg L(-1), 24 and 41% improvements, respectively, with 90% confidence. Overall, the Monte Carlo simulation in the integrated modelling system was practical for estimating uncertainty and reliable in water quality prediction. The approach described here may allow decisions to be made based on the probability and level of risk, and its application is recommended.     

Steroidal glycosides of the 14,15-seco-18-nor-pregnane series from Cynanchum ascyrifolium

Three new steroidal glycosides named cynascyrosides A-C were isolated from the roots of Cynanchum ascyrifolium. The structures of these compounds were determined on the basis of spectroscopic and chemical evidence as cynajapogenin A 3-O-alpha-D-oleandropyranosyl-(1-->4)-beta-L-cymaropyranosyl -(1-->4)-beta-D- digitoxopyranoside; cynajapogenin A 3-O-beta-D-glucopyranosyl-(1-->4)-alpha-L-cymaropyranosyl- (1-->4)-beta-L-cymaropyranosyl-(1-->4)-beta-L-cymaropyranoside+ ++; cynajapogenin A 3-O-beta-D-glucopyranosyl-(1-->4)-alpha-L-cymaropyranosyl- (1-->4)-beta-D-digitoxopyranosyl-(1-->4)-beta-L-cymaropyranosid e.