The stress-corrosion cracking of aluminum-coated U-4.5 wt% Nb

Room temperature ($\text{26 ± 2}$°C) tests show that the aged (80 h at 260°C) U-4.5 wt% Nb alloy can be protected from stress-corrosion cracking in aqueous chloride environments by coating the alloy with aluminum.     

Effects of zirconium doping on the characteristics of tin oxide thin film transistors

Thin-film transistors (TFTs) with zirconium-doped tin oxide (ZSO) channels were fabricated by co-sputtering Sn and Zr metal targets. The effect of Zr on the performance of SnO_x-based TFTs was studied. TFTs with an intrinsic SnO_x channel did not show promising performance. However, ZSO TFTs exhibited improved electrical properties, with increased I_ON/I_OFF and decreased subthreshold swing. The influence of zirconium doping on bias stability in tin oxide TFTs was also investigated. ZSO TFTs exhibited turn-on voltage (V_ON) shifts of +9 V for positive stress bias, compared with +18 V for intrinsic SnO_x TFTs. The improvements in device performance and stability were attributed to reduced carrier concentration induced by carrier trapping at Zr impurity sites.     

Quality and mold control of enriched white bread by combined radio frequency and hot air treatment

This study explored the application of radio frequency (RF) energy in conjunction with conventional hot air treatment to provide uniform heating for control of mold in pre-packaged bread loaf. A 6 kW, 27.12 MHz RF system was used to develop treatment protocols. The treatment parameters were selected based on minimum time-temperature conditions that were required for 4-log reduction of Penicillium citrinum spores while yielding acceptable bread quality. During combined RF and hot air treatments, the core and periphery of the bread loaf were heated together with almost the same heating rate. The maximum temperature difference within one bread slice was less than 5 °C. The moisture contents and water activities of RF treated samples first increased and then decreased compared to those of untreated samples, while firmness increased during the storage for both heat treated and untreated samples, yet the overall differences in sample qualities between RF treated bread samples and control were not significant. Because of better heating uniformity, much lower mean product temperature and shorter holding time were used for control of P. citrinum spores with combined RF and hot air treatment as compared to conventional heating alone. Heating bread to 58 °C or higher resulted in 4-log reduction of P. citrinum spores isolated from moldy bread. The storage life at room temperature (23 °C) was extended by 28 ± 2 days for the treated white bread.     

Biogenic amine formation and bacterial contribution in fish,squid and shellfish

Forty-one species of fish, squid and shellfish were analyzed for biogenic amine (BA) contents. Most of the fish samples showed lower BA contents, whereas some samples showed higher contents than the allowable levels. Shellfish and squid samples had negligible BA levels. Four fish species containing high BA levels were analyzed for changes in histamine contents during storage. In the most samples, the histamine contents remarkably increased up to 36.6–2123.9 mg/kg after 24 h of storage at 25 °C, while the contents began to gradually increase after 2–3 days of storage at 4–10 °C. The dominant microbial group was enterobacteria throughout the storage period. Meanwhile, out of total 119 strains isolated from different fish species showing high BA levels, 23 strains identified as Enterobacter aerogenes produced large amounts of histamine, putrescine and cadaverine, and 33 strains identified as two different Enterobacter spp. produced less histamine but large amounts of putrescine and cadaverine.     

Surface properties of etched ITO thin films using high density plasma

The etching characteristics of ITO in a BCl₃/Ar plasma, including the etch rate and selectivity of ITO, were investigated. The maximum etch rate of 62.8 nm/min for the ITO thin films was obtained at a BCl₃/Ar gas mixing ratio of 25%/75%. Ion bombardment by physical sputtering was required to obtain such high etch rates, due to the relatively low volatility of the by-products formed during the etching. The chemical reactions on the etched surfaces were investigated using X-ray Photoelectron Spectroscopy (XPS) and the preferential losses on the etched surfaces were investigated using Atomic Force Microscopy (AFM).     

Morphological study of heat-sensitive and heat-resistant spores of Clostridium sporogenes, using transmission electron microscopy

To investigate the primary structural determinants affecting heat resistance of Clostridium sporogenes spores, electron micrographs of heat-sensitive (D121 degrees C = 0.56 min) and heat-resistant (D121 degrees C = 0.93 min) spores of C. sporogenes were taken with a transmission electron microscope. The mean thickness (+/- standard deviation [SD]) of coat layers and cortex regions of heat-sensitive spores were 82.9 +/- 14.5 and 86.0 +/- 22.7 nm, while those of heat-resistant spores were 106.9 +/- 45.7 and 111.7 +/- 32.1 nm, respectively. The thickness of coat (P = 0.031) and cortex (P = 0.006) showed statistically significant differences, suggesting that heat-resistant spores have a thicker coat and cortex than do heat-sensitive spores. The mean sizes (+/- SD) of cores were 467.0 +/- 88.7 nm for heat-sensitive spores and 460.2 +/- 98.5 nm for heat-resistant spores, respectively, which showed no statistically significant differences. The ratios (+/- SD) of the core size to the sporoplast size were 0.84 +/- 0.05 for heat-sensitive spores and 0.80 +/- 0.07 for heat-resistant spores, respectively, showing statistically significant differences (P = 0.030), which indicated that the ratio is negatively related to heat resistance. Accordingly, the structural components of heat-sensitive spores were severely damaged by heat treatment, whereas those of heat-resistant spores were unlysed under the same conditions. Based on the structural analyses of spores, it was elucidated that the thickness of coat layer and cortex region are significantly correlated with heat resistance of C. sporogenes spores, and that cortex region plays a major role in protecting the spore from heat damage.     

Comparison of modified newton's methods

A comparative evaluation was made of the performance of the Broyden-Schubert method, the finite-difference Newton's method and a hybrid method. Four problems deried from the simulation of a natural gas liquefaction process were used as bench-marks. The results show the hybrid method to be an effective combination of the advantages of the two methods with modest but worthwhile savings in computing time.     

High-Temperature Environmental Stability of the Compounds in the Al2O3–Y2O3 System

Heat treatments in several environments were performed on a series of compounds in the Al₂O₃ and Y₂O₃ system: Al₂O₃Y₃Al₅O₁₂ eutectic, Y₃Al₅O₁₂, YAlO₃, Y₄Al₂O₉, and Y₂O₃. The yttrium aluminates were found to be stable at high temperatures under vacuum and in air. However, when they were heat-treated under vacuum in proximity to SiC, degradation was observed. This was found to be primarily a result of carbothermal reduction. In a similarly reducing environment without Si, the yttrium aluminates, and Al₂O₃ and Y₂O₃, all exhibited degradation by carbothermal reduction. Based upon the experimental results, a degradation mechanism for yttrium aluminates was proposed.     

Mechanical behaviour of polycrystalline TiC

The mechanical behaviour of hot-pressed TiC was studied. Compacts were fabricated from commercially available TiC powders, which were found to contain impurities including iron, cobalt, silicon and free carbon. Those impurities segregated to the grain boundaries and formed low melting-point phases which degraded the high-temperature strength. Differences in the temperature at which strength began to fall sharply were correlated with differences in the impurity chemistry of the TiC starting powders. It was found that a high-temperature vacuum heat treatment of the as-hot-pressed TiC significantly reduced the levels of impurities at the grain boundaries. This, in turn, caused a dramatic improvement in high-temperature strength. The TiC, so treated, possessed a grain size of approximately 25μm and exhibited a D-B transition in bending at about 1425° C.