Two stage procedure having exact consistency and second order properties for the s best selection

We consider the problem of selecting the populations associated with the (1≤s<k) largest location parameters out of k(≥2) independent populations with a common scale parameter, while satisfying the preassigned probability requirement exactly and enjoying second-order properties simultaneously. Two distributional cases are considered: i Normal distribution; and ii negative exponential distribution. A two­stage procedure is proposed to give such a selection rule for each case of (i)-(ii) under Mukhopadhyay and Duggan's (1999) assumption. The design constant in the proposed procedure is tabulated compared with rhe corresponding approximate value which is computed by using an asymptotic expansion formula     

Fabrication of poly(vinyl alcohol)s (PVAs) nanotubes through the fusion of nanocapsules composed of PVAs multilayer films

Poly(vinyl alcohol) (PVA) nanocapsules were fabricated by the deposition of PVA multilayer films onto the surface of silica particles followed by the removal of the silica cores. When a water dispersion of PVA nanocapsules was dried on a substrate, PVA nanotubes were formed through the one-dimensional fusion of the nanocapsules. This fusion behavior of the PVA nanocapsules was strongly affected by the molecular weights and acetylation degrees of PVA, the capsule film thickness of the PVA nanocapsules and the temperature to dry a water dispersion of the nanocapsules. When nanocapsules composed of 20 layered films of acetylated PVA with a 14% acetylation degree were used, nanotube formation via the fusion of these nanocapsules occurred effectively upon drying the water dispersion at 20 °C.     

Surface control of hydrophilicity and degradability with block copolymers composed of lactide and cyclic carbonate bearing methoxyethoxyl groups

Block copolymers of L-lactide (LA) and trimethylene carbonate (TMC) derivatives bearing methoxyethyl groups [poly(TMCM-MOE1OM)-block-PLLA] were employed as spin-coated films on substrates, and their hydrophilic and degradation behaviors were investigated. Changing the solvents for film preparation, film thickness, and copolymer composition ratios varied the contact angles in the range of 84.3° ± 2.8° at 269 nm thickness and 18.2° ± 2.5° at 15 nm thickness. These contact angles showed dynamic changes from hydrophobic to hydrophilic properties, probably due to the methoxyethoxyl groups connecting the flexible TMC moieties in the copolymer. Immersion into water or hexane affected the dynamic contact angles. X-ray photoelectron spectroscopy analyses revealed that a large amount of hydrophilic groups was segregated onto the surface, although both LA and TMC units existed. Such dynamic contact angle changes were delayed by the crystallization of polylactide. The hydrolyzed behaviors of these films were examined by quartz cell microbalance, showing a slow degradation process.     

Synthesis and characterization of novel biodegradable polymers composed of hydroxycinnamic acid and D,L-lactic acid

D,L -Lactic acid (DLLA) was polycondensed with 4-hydroxycinnamic acid (4HCA), a derivative of cinnamic acid, to prepare a novel functional biodegradable polymer. The polymer was prepared using two different methods, the solvent method, which used acetic anhydride as the solvent, and the direct method. White and brown-colored copolymers were obtained by these two methods, respectively. ¹H-NMR spectroscopy and UV-visible spectroscopy revealed that the double bond of 4HCA was almost completely destroyed when the copolymer was prepared by the direct method. On the other hand, copolymers in which the double bond was preserved in the 4HCA–DLLA copolymer were successfully obtained using the solvent method. The solubility of the copolymers obtained by the solvent method in organic solvent was poor. When the copolymer was prepared under a 4HCA:DLLA ratio of 20:80 using the solvent method, the resulting copolymer had high solubility in organic solvents and the double bond was preserved. Moreover, it was confirmed that the 4HCA–DLLA copolymer synthesized by the solvent method was both photoreactive and biodegradable. The 4HCA–DLLA copolymer is expected to be used as basic material for tissue engineering and drug delivery systems, in addition to applications as an orthopedic matrix and a degradable plastic. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2357–2364, 2001     

Adhesive failure peak in peel spectra

Peel force spectra for pressure‐sensitive adhesive tapes provide a peel peak in the adhesive failure region. The observed peak behavior is coincident with calculation based on a viscoelastic peel model. It turns out that the origin of the peak is significantly associated with viscoelasticity or short relaxation time of the adhesive. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 264–266, 1999     

Analyzing the influence of changes in land use and management practices on the lag time of peak flows for tropical watersheds of Ethiopia

Changes in peak flow response time governed by rainfall and physical configurations of watersheds have been the topic of many studies, but other factors are also important. We aimed to analyze the dynamics in the lag time (T_L) of peak flow for a tropical watershed (Kecha) and its sub-watersheds (Dokmit, Zenjero Maderia, and Wotit Minch) in Ethiopia, as influenced by land-use changes from 1982 to 2017 and the implementation of soil and water conservation (SWC) practices since 2011. Layered maps of land use, soil type, and SWC practices were used to determine the curve number, and the Natural Resource Conservation Service hydrologic model was used to estimate T_L. We compared the estimated values against measured median values of T_L for 30 rainfall–runoff events. The estimated T_L of 1982, 2005, and 2017 varied from 9 to 19 min, 8 to 18 min, and 10 to 22 min, respectively, in the Dokmit, Zenjero Maderia, and Wotit Minch sub-watersheds. The smallest (8 min) and greatest (22 min) values of T_L were observed during 2005 and 2017, respectively. These results are likely attributable to the increased amount of cultivated area at the expense of bushland and forest in 2005 as compared to 1982, and the implementation of SWC practices in 2011–2017. Dokmit had the lowest T_L values of the three sub-watersheds, most likely because of its greater coverage of grazing and cultivated lands and degraded Nitic Luvisol. The variation in T_L values among the sub-watersheds was related to changes in both land use and SWC practices but also to the presence of degraded areas inherited from past human activities. Overall, such spatiotemporal flow response time analysis can provide useful information for the proper design of sustainable development strategies for particular niches in tropical regions of Ethiopia and elsewhere.     

Digestibility of Sweet Potato Raw Starches by Glucoamylase

Three crude glucoamylase preparations from Rhizopus sp., Chalara paradoxa and Aspergillus sp. K-27 were used to determine the digestibility of raw starches from eight sweet potato varieties. Granule sizes and amylose contents were also measured. The average granule sizes ranged between 10.5 and 14.2 μm. The amylose contents varied between 18.2 and 21.8%. The hydrolysis rates for the raw starches by any of the three glucoamylases were similar. However, starch of the variety Hi-starch had a slightly lower hydrolysis rate than other starches when Rhizopus sp, enzyme was used.     

GaAs solar cells grown on Si substrates for space use

GaAs single‐junction and InGaP/GaAs multi‐junction thin‐film solar cells fabricated on Si substrates have great potential for high‐efficiency, low‐cost, lightweight and large‐area space solar cells. Heteroepitaxy of GaAs thin films on Si substrates has been examined and high‐efficiency GaAs thin‐film solar cells with total‐area efficiencies of 18·3% at AM0 and 20·0% at AM 1·5 on Si substrates (GaAs‐on‐Si solar cells) have been fabricated. In addition, 1‐MeV electron irradiation damage to GaAs‐on‐Si cells has been studied. The GaAs‐on‐Si cells are found to show higher end‐of‐life efficiency than the conventional GaAs cells fabricated on GaAs substrates (GaAs‐ on‐GaAs cells) under high‐fluence 1‐MeV electron irradiation of more than 1 × 10¹⁵ cm⁻². The first space flight to make use of them has been carried out. Forty‐eight 2 × 2 cm GaAs‐on‐Si cells with an average AM0 total‐area efficiency of 16·9% have been evaluated in the Engineering Test Satellite No.6 (ETS‐VI). The GaAs‐on‐Si cells have been demonstrated to be more radiation‐resistant in space than GaAs‐on‐GaAs cells and 50, 100 and 200‐μm‐thick Si cells. These results show that the GaAs‐on‐Si single‐junction and InGaP/GaAs‐on‐Si multi‐junction cells have great potential for space applications. Copyright © 2001 John Wiley & Sons, Ltd.