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The formation of the insulating A1O[sub x] tunnel barrier is a critical and sensitive process in magnetic tunnel junctions. Both the natural oxidation and the plasma oxidation methods were employed to fabricate the A1O[sub x] insulating layer in this study. In the natural oxidation, the A1 layer was exposed to pure oxygen gas at 20 Torr for up to 50 min to produce the A10[sub x] tunnel barrier. It was revealed by high resolution transmission electron microscopy that the oxidation occurred preferentially through the grain boundary of A1 grains. Also, the A10[sub x] grains expanded isotropically when fully oxidized, thereby making the surface of the A1O[sub x] layer modulated. In plasma oxidation, the oxygen plasma was used at 20 mTorr of pure oxygen gas for up to 30 s and the flat A10[sub x] layer formed uniformly on the A1 layer. It had sharp interfaces with the underlying metallic A1 and the rate of oxide layer growth decreased as the oxidation proceeded. [ABSTRACT FROM AUTHOR]

Abstract: Turanose, a structural isomer of sucrose, is a non-cariogenic and low-calorigenic disaccharide. It has a promising potential to be a high-quality functional sweetener, but there has been no competitive way to produce turanose until now. In this study, a recombinant amylosucrase, originating from Neisseria polysaccharea (NpAS), was utilised to efficiently convert sucrose to turanose. With 2.5M sucrose and 400U/l of NpAS, the production yield of turanose maximally reached to 56.2% at 35°C after a 120h reaction. Main transglycosylating reaction pathway of NpAS clearly shifted from α-(1,4)-glucan synthesis to turanose production by simply increasing sucrose substrate concentration. Purification, by a preparative recycling HPLC, effectively separated turanose from the reaction mixture with a high purity of 94.7% and a high recovery yield of 97.5%. Chemical structure of the purified turanose was confirmed by NMR analysis, and three tautomers, namely 3-O-α-d-glucopyranosyl-α-d-fructofuranose, 3-O-α-d-glucopyranosyl-β-d-fructofuranose, and 3-O-α-d-glucopyranosyl-β-d-fructopyranose, were identified with a ratio of approximately 1:2:2. [Copyright &y& Elsevier]

Abstract: A major chromatographic peak of anthocyanin from ogaja (Acanthopanax sessiliflorum) fruit represented 95.4% of total absorbable compounds at 518nm. The mass-to-charge ratio (m/z) of this colorant was determined to be 581 by LC–MS, which was identical to the molecular mass of cyanidin-3-O-sambubioside. After acid hydrolysis of the purified anthocyanin fraction, it was structurally confirmed by thin layer chromatography (TLC) and high-performance anion exchange chromatography (HPAEC) analyses. As a result, the sugar moieties linked to cyanidin were glucose and xylose. The purified cyanidin-3-O-sambubioside and cyanidin had greater antioxidant activities than l-ascorbic acid by both DPPH and ABTS methods. Cyanidin-3-O-sambubioside was more stable than cyanidin in the response to heat (80°C), and both fluorescent and UV light. l-Ascorbic acid had an adverse effect on the color stability of anthocyanin. In this study, we demonstrated that glycosylation on anthocyanidin would provide an effective protection barrier for its color stability against the exposure to various food processing conditions. [Copyright &y& Elsevier]

The exchange field of Cu(50 A˚)/FeMn(50 A˚)/Co(50 A˚) sputtered on Si substrate was studied in terms of surface roughness and phase formation of γ-FeMn under a variety of Ar pressures and powers in sputtering. It was found that the exchange field is stronger when the surface is smoother and the FeMn layer forms better. The exchange bias field increased by more than three times after heat treatment. The effect of heat treament on magnetoresistance (MR) and resistance of the top spin valve, substrate/Co(30 A˚)/Cu(30 A˚)/Co(30 A˚)/FeMn(150 A˚), was studied. It was observed that the MR started to increase with annealing temperature and the effect was significant at 150°C. The heat treatment led to the disappearance of the intermixed layer between Co and Cu, and the concentration profile of Cu became flat and smooth at this temperature. [Copyright &y& Elsevier]

In a magnetic tunnel junction, the formation of an insulator is sensitive and critical to the stable performance and reproducibility of the junction. The oxidation path and the microstructural change with time of the insulator in natural oxidation have been studied by the high-resolution transmission electron microscopy. It has been observed that the oxidation path is primarily through the grain boundary at an early stage of oxidation and then through the grains at a later stage. The morphology of the oxide layer was rugged and modulated. There also occurred an isotropic volume expansion with increased oxidation. It was observed that the ferromagnetic Co layer below an insulator was partially oxidized because of the preferred grain boundary oxidation. When this multilayer was annealed, the locally oxidized Co layer was reduced and the metallic layer formed as a continuous film type, thereby improving the interface. [ABSTRACT FROM AUTHOR]

Abstract: The fruit of Schizandra chinensis Baillon is a well-known traditional medicinal plant in Korea, China and Japan. We examined the effects of gamma irradiation on decolourisation and biological activity of S. chinensis fruit extracts to facilitate industrial applications. Samples were exposed to gamma-ray irradiation from 0.5 to 10kGy. Irradiation of greater than 2kGy markedly reduced the major colourant in S. chinensis fruit extracts, cyanidin-3-O-xylosylrutinoside (Cya-3-O-xylrut), by 80–90%. Biological activities, such as radical-scavenging activity and elastase inhibition activity, were not affected by gamma irradiation, but we observed a 12.3% increase in tyrosinase inhibition activity. There were negligible changes in the amounts of the major lignans schizandrin, gomisin A and gomisin N, following irradiation. These results indicated that gamma irradiation can selectively remove undesirable colour in S. chinensis extracts without adverse changes in biological activity. [ABSTRACT FROM AUTHOR]