The relationship between sensitisation and small punch test behaviour in a high-nitrogen austenitic stainless steel at cryogenic temperatures

Austenitic stainless components used in nuclear fusion reactors must be capable of maintaining reasonable mechanical properties to thermal ageing caused by welding and in‐service. Recently, high‐nitrogen (High‐N) austenitic stainless steels (SS) are receiving increased attention because of their strength advantages, but they have been found to be susceptible to dichromium nitride (Cr₂N) precipitation during thermal exposure at 823–1073 K. The susceptibility to sensitisation at thermal ageing temperature for high‐N austenitic SS is examined using the single‐loop electrochemical potentiokinetic reactivation (EPR) test. High‐N SS were found to be susceptible to sensitisation caused by grain boundary precipitation of Cr₂N, with the degree of sensitisation increasing systematically with ageing time and temperature. In particular, it was found that the precipitates, which effected sensitisation, were changed from carbides (M₂₃C₆) to nitrides (Cr₂N) with increasing ageing time and temperature. The deterioration of mechanical properties associated with thermal ageing in high‐N SS was investigated by a small punch (SP) test using miniature specimens at cryogenic temperatures. Results indicated that the degradation of mechanical properties in this alloy was caused by a decrease of cohesive strength resulting from carbides (Cr₂₃C₆) and nitrides (Cr₂N) precipitated in grain boundaries.     

Effects of Cr interlayer on mechanical and tribological properties of Cr-Al-Si-N nanocomposite coating

Cr-Al-Si-N coatings were deposited on SUS 304 substrate by a hybrid coating system. A Cr interlayer was introduced between Cr-Al-Si-N coating and SUS 304 substrate to improve the coating adherence. The effects of Cr interlayer on the microhardness, adhesion, and tribological behavior of Cr-Al-Si-N coatings were systematically investigated. The results indicate that the microhardness of the Cr-Al-Si-N coatings gradually deceases with increasing thickness of Cr interlayers. The adhesion between Cr-Al-Si-N and SUS 304 substrate is improved by addition of the Cr interlayers. A peak critical load of ~50 N is observed for the coating containing Cr interlayer of 60 nm as compared ~ 20 N for the coating without Cr interlayer. The thicker Cr interlayers result in reduced critical load values. Moreover, the wear resistance of the Cr-Al-Si-N coatings is greatly enhanced by introducing the Cr interlayer with thickness of 60 nm in spite of the decreased microhardness. The friction coefficient of the coating system is also moderately reduced.     

Correlation Between Oxidative Deterioration of Unsaturated Lipid and n-Hexanal during Storage of Brown Rice

n-Hexanal in the headspace over cooked brown rice stored at 5°C and 35°C for 0, 4, 8 and 12 months was determined by a gas chromatographic method using modified direct vapor injection. The off-flavors of stored brown rice were evaluated by n-hexanal and oxidized linoleic acid analysis. The amount of n-hexanal was found to be linearly proportional to the amount of oxidized linoleic acid (correlation coefficient, 0.99). Therefore, the simple and rapid method of vapor injection gas chromatography can be used for determining n-hexanal in the headspace vapor over cooked brown rice. Thus, the off-flavor of the stored brown rice resulting from lipid oxidation can be detected indirectly.     

FEEDING LOW CALCIUM AND ZINC MOLT DIETS SUSTAINS GASTROINTESTINAL FERMENTATION AND LIMITS SALMONELLA ENTERICA SEROVAR ENTERITIDIS COLONIZATION IN LAYING HENS

The objective of these experiments was to determine whether alternative molting diets would minimize Salmonella enterica serovar Entertitidis (S. Enteritidis) colonization in molting hens. Hens were randomly assigned to four treatment groups of 12 hens either full‐fed (nonmolt, NM), molted by feed withdrawal (molt, M), a low calcium (LC containing 800 mg calcium), or LC diet supplemented with 110 mg zinc/ kg of diet (LC‐ZN) in two trials. All hens were challenged orally with 10 ⁵SE on day 4 of experiment. Hen body weight loss was significantly (P < 0.05) increased and ovarian weight was significantly (P < 0.05) decreased in hens fed the LC or LC‐ZN diets compared to NM. Cecal lactic acid concentrations were significantly (P < 0.05) increased in hens fed alternative molting diets. Feed withdrawal molted hens exhibited significantly (P < 0.05) more S. Enteritidis positive and S. Enteritidis crop, cecal, and organ colonization than NM, LC and LC‐ZN hens. Alternative molt diets retain sufficient fermentative activity to limit S. Enteritidis colonization and therefore may have potential to avoid the risk of increasing S. Enteritidis colonization associated with feed withdrawal.     

二等奖岛岛

我们把注意力投向了“自然意志”之间悖论性的循环机制,在这种机制下从jungrang溪冲积下来的淤沙创造了岛屿,而人们为了控制洪水不断努力地清理着这些淤泥。我们同时无意间揭示了一个事实,疏清出来的淤泥被归为一种“工业废弃物”。我们希望做的是利用这种由溪流不断提供的将汉江与首尔之城重新联系的自然资源。虽然我们始自虚无,希冀的却是那无穷的扩展。我们相信自己在这个项目的场地中所做的工作会扩展到超过其预期的尺度。     

Friction stir butt welding of A5052-O aluminum alloy plates

Friction stir butt welding (FSW) between A5052-O aluminum alloy plates with a thickness of 2 mm was performed.The rotation speeds of the welding tool were 2000 and 3000 r/min,respectively.The traverse speed was ranged from 100 mm/min to 900 mm/min.The defect-free welds with the very smooth surface morphology were successfully obtained,except for at the welding condition of 3000 r/min and 100 mm/min.The onion ring structure was observed in the friction-stir-welded zone (SZ) at the condition of 2000 r/min and 100 mm/min.For all the welding conditions,the grain size of the SZ was smaller than that of the base metal,and was decreased with the decrease of the tool rotation speed and with the increase of the tool traverse speed.The stir zone exhibited higher average hardness than the base metal.The decrease of the tool rotation speed and the increase of the tool traverse speed resulted in the increase in the average hardness of the SZ.The tensile strength of the FSWed plates was similar to that of the base metal,except for at the welding condition of 3000 r/min and 100 mm/min.The total elongation of the FSWed plates was lower than that of the base metal.     

真空热压铝和铜的固态连接(英文)

在温度623~923K下采用真空热压扩散连接铝和铜,具体工艺为在预置温度下,变形率为0.2mm/min时热压缩10min,再在炉冷过程中,以0.2mm/min成型10min。通过界面分析可以看出,合适的扩散连接温度为823K,在扩散过程中产生了3种主要的金属间化合物层,分别为Al2Cu、AlCu+Al3Cu4和Al4Cu9。3种化合物层的局部硬度分别为(4.97±0.05)、(6.33±0.00)、(6.06±0.18)GPa。     

OVER-EXPRESSION OF PROLINE-LINKED ANTIOXIDANT PATHWAY AND MODULATION OF PHENOLIC METABOLITES IN LONG LIFE SPAN CLONAL LINE OF ORIGANUM VULGARE IN RESPONSE TO ULTRAVIOLET RADIATION

Tissue culture-generated shoot-based clonal lines of oregano that have a short and long life span during in vitro culture were investigated to determine the role of proline-linked pentose phosphate pathway in modulating phenolic response following ultraviolet (UV) exposure. This novel reductant cycling pathway for energy and oxidative pentose phosphate pathway (PPP) is more efficient in long life span O-17 clonal line in response to UV and this supported antioxidant response. UV treatment stimulated rosmarinic acid and associated antioxidant enzyme response in O-17 clonal line compared with short life span O-3 clonal line. Additionally, O-17 clonal line had higher glucose-6-phosphate dehydrogenase and guaicol peroxidase activity in response to UV exposure compared with O-3 clonal line, indicating stimulation of anabolic pathway supporting PPP during UV treatment. The stimulation of proline dehydrogenase (PDH) activity in O-17 clonal line in response to UV indicated a switch to PDH-linked energy pathway via proline oxidation.

PRACTICAL APPLICATIONS

This oregano clonal model of ultraviolet (UV)-induced oxidative stress management has implications for designing dietary phytochemicals to manage oxidation-linked disease in humans. Further, the correlation between UV-linked inducibility of phenolic-linked antioxidant enzyme response through proline-linked pentose phosphate pathway and life span of in vitro shoot cultures of specific oregano clonal lines can be a good model for aging studies. The metabolic response link to aging and protective phytochemicals can be investigated in oregano tissue cultures, and phenolic extracts from various responding clonal lines could be explored in other eukaryotic aging models.     

Effects of Gamma Irradiation Dose and Timing of Treatment after Harvest on the Storeability of Garlic Bulbs

The effect of gamma irradiation dose and time of treatment after harvest on the storage of garlic bulbs was investigated. The effectiveness of irradiation for external sprout inhibition was not affected by the treatment time within 45 days after harvest. At 285 days after harvest, irradiation of 50 - 150 Gy caused about 6% less decrease in weight loss compared with the unirradiated group, and spoilage rates of the unirradiated and irradiated cloves were 100% and 17 - 20%, respectively. For the overall storageability of garlic bulbs, 75 Gy was shown to be the minimal optimum dose, and there was no apparent effect depending upon the time of irradiation treatment after harvest.