High resolution optical microprobe investigation of surface grinding stresses in Al2O3 and Al2O3/SiC nanocomposites

It has previously been suggested that Al₂O₃/SiC nanocomposites develop higher surface residual stresses than Al₂O₃ on grinding and polishing. In this work, high spatial resolution measurements of residual stresses in ground surfaces of alumina and nanocomposites were made by Cr³⁺ fluorescence microspectroscopy. The residual stresses from grinding were highly inhomogeneous in alumina and 2 vol.% SiC nanocomposites, with stresses ranging from ～ ?2 GPa within the plastically deformed surface layers to ～ +0.8 GPa in the material beneath them. Out of plane tensile stresses were also present. The stresses were much more uniform in 5 and 10 vol% SiC nanocomposites; no significant tensile stresses were present and the compressive stresses in the surface were ～ ?2.7 GPa. The depth and extent of plastic deformation were similar in all the materials (depth ～ 0.7–0.85 μm); the greater uniformity and compressive stress in the nanocomposites with 5 and 10 vol% SiC was primarily a consequence of the lack of surface fracture and pullout during grinding. The results help to explain the improved strength and resistance to severe wear of the nanocomposites.     

Thailand Experience in Developing Wellness-driven Rice as the Key to Fight NCDs and Farmer Poverty(Online First, Recommended Article)

近年来,非传染性慢性疾病的发病率迅速上升,已成为一个全球性的问题。过度食用简单的加工碳水化合物食品被认为是导致年轻人和老年人罹患非传染性慢性疾病的主要原因之一。全谷物米是碳水化合物、膳食纤维的重要来源,富含维生素、矿物质和抗氧化剂。然而,糙米的适口性是其在长期以白米消费为主的人群中被接受的关键因素。在初始阶段,我们成功培育出了水稻品种,其全谷物米芳香、柔软且白米具有较高的铁锌密度和中血糖指数（GI）。最成功的品种是独特的具有较软质构的黑紫色稻米,名为紫莓香米（Riceberry）,富含蓝莓花青素等营养物质的稻米。针对富含膳食纤维、高抗氧化活性的稻米产品研发一直是学术界、实体部门和中小企业极为活跃的领域,目前共有关于紫莓香米相关的39项专利申请（18项已授权专利）、12项国际出版物、以及18 700个与紫莓香米有关的YouTube视频。从2017年开始,紫莓香米已超越泰国Hom茉莉香米（Thai Hommali Rice）成为最受欢迎的产品开发选择原料,已有超过200种作为乳制品替代品、配菜、主餐食品、热饮料、烘焙食品和早餐麦片等的商业化食品和非食品产品。在第二阶段,我们成功地培育出了名为Pink+4的低血糖指数水稻品种,该品种具有对骤发洪水、水稻白叶枯病、稻瘟病和破坏性褐飞虱的首选抗性,适用于有机水稻生产。以紫色紫莓香米为原料的低GI米粉创新产品已成为功能性配料和功能性食品的下一个发展趋势。这些健康的稻米产品在全球具有较好的发展潜力,可以作为健康食品、无麸质、富含纤维、复杂碳水化合物和可持续有机农业的营养密集型产品。     

Effect of composition and grain size on dielectric,ferroelectric and induced strain behavior of PLZT/ZrO2 composites

Lead lanthanum zirconate titanate ceramics (PLZT) are well known for their excellent dielectric, piezoelectric and ferroelectric properties. In this study, PLZT 9/70/30, 9/65/35 and 9/60/40 ceramics were prepared by vibro-milling mixed-oxide method. All compositions of powders were uniaxial pressed in pellets and sintered at the temperatures of 1200–1275 °C with various soaking times of 2, 4 and 6 h. The X-ray diffraction (XRD) patterns confirmed that all the PLZT samples had perovskite structure with ZrO₂ as a second phase and PLZT/ZrO₂ composite structure was formed. Dielectric behavior at the frequency of 1 kHz showed broad peak indicating relaxor ferroelectric behavior and the difference of the temperature at maximum dielectric at different frequencies increased when Zr:Ti ratio increased. Polarization with electric field (P-E loop) at room temperature showed that when Zr:Ti ratio increased, the coercive field decreased resulting from crystal structure change from tetragonal to rhombohedral. Induced strain with electric field depended on microstructure where the value of S_max/E_max tended to decrease with increasing grain size. It can be concluded that dielectric and ferroelectric behavior predominantly depended on composition of PLZT ceramics and induced strain behavior predominantly depended on grain size of PLZT ceramics.     

Anthocyanin content and antioxidant capacity in bran extracts of some Thai black rice varieties

This study investigated both the anthocyanin content and the antioxidant capacity of a set of genetically related glutinous and nonglutinous Thai black rice varieties. The ethanol/water extracts of the brans of these black rice varieties showed relatively potent antioxidant activities compared with those of tocopherol. These antioxidant activities were determined by thiocyanate, H₂O₂‐scavenging chemiluminescence (XYZ), Cu⁺⁺/bathocuproine colorimetry (PAO) and 1,1‐diphenyl‐2‐picrylhydrazyl radical‐scavenging assay. The structural identification and quantification of the black rice anthocyanins performed by high‐performance liquid chromatography coupled with electrospray ionisation and tandem mass spectrometry found cyanidin‐3‐O‐glucoside and peonidin‐3‐O‐glucoside as the major anthocyanins in the ranges of 16.01–34.40 and 2.43–7.36 μg mL^?1, respectively. The comparative study in terms of quantity of these phytochemicals and antioxidant capacity of the black rice bran extracts suggested the contribution of overall phenolic components rather than that of the particular anthocyanin pigments.     

Drying characteristics of Shiitake mushroom and Jinda chili during vacuum heat pump drying

Drying characteristics of the Shiitake mushroom and Jinda chili, a commonly grown variety in the Northeast of Thailand, was investigated under varying conditions of the drying temperatures (50, 55, 60 and 65 °C) and the vacuum pressures (0.1, 0.2, 0.3 and 0.4 bar) in a new design of a vacuum heat pump dryer. Nine different thin layer mathematical drying models were compared according to their correlation coefficient, reduced chi-square and root mean square error to estimate vacuum heat pump drying curves. The result indicates that the Midilli model can present better predictions than the others. The constants and coefficients of this model could be explained by the effect of the drying temperature and the drying pressure. The drying temperature and pressure significantly affects color degradation (probability P < 0.05). Drying temperature has little effects on rehydration capacity (probability P > 0.05). Rehydration capacity notably decreases with an increase in the vacuum pressure.     

The relationship between microstructure,fracture and abrasive wear in Al2O3/SiC nanocomposites and microcomposites containing 5 and 10% SiC

Alumina/SiC nanocomposites are much more resistant to severe wear than monolithic alumina. In order to clarify the mechanisms responsible for these improvements, alumina and alumina/SiC nanocomposites with 5 and 10 vol.% SiC and various alumina grain sizes were fabricated. For comparison, a 10 vol.% SiC “microcomposite” was also fabricated using 3 μm SiC particles. The extent of cracking beneath hardness indentations was examined and the specimens were tested in abrasive wear. Quantitative surface fractography of the worn surfaces was carried out. The wear properties depended strongly on the grain size in pure alumina, but were independent of the alumina grain size in the nanocomposites. This is consistent with the idea that much of the improvement in wear resistance when SiC is added to alumina stems from a reduction in the size of the individual pullouts owing to the accompanying change in fracture mode. In addition, crack initiation by plastic deformation during abrasion and indentation was found to be strongly inhibited when 10 vol.% nanosized SiC was added to alumina. The addition of 3 μm “micro-sized” SiC did not have the same effect. The ability of fine SiC particles to suppress cracking is attributed to the blocking of twins and dislocation pileups by intragranular SiC nanoparticles. This reduces the length of the twins or pileups and hence their ability to nucleate microcracks.     

Electrospun gelatin fiber mats containing a herbal-Centella asiatica-extract and release characteristic of asiaticoside

Ultra-fine gelatin (type A, porcine skin, ～180 Bloom) fiber mats containing a methanolic crude extract of Centella asiatica (L.) Urban, a medicinal plant widely known for its traditional medical applications including its wound healing ability, were fabricated, for the first time, from the neat gelatin solution (22% w/v in 70?vol% acetic acid) containing the crude extract (mCA) in various amounts (i.e. 5-30?wt% based on the weight of gelatin powder) by electrospinning. Incorporation of mCA in the neat gelatin solution did not affect both the morphology and the size of the mCA-loaded gelatin fibers, as both of the neat and the mCA-loaded gelatin fibers were smooth and the average diameters of these fibers ranged between 226 and 232?nm. The cross-linked mCA-loaded e-spun gelatin fiber mat from the neat gelatin solution containing 30?wt% of mCA was further investigated for the release characteristic of asiaticoside, identified as the most active compound associated with the healing of wounds, in two different types of releasing medium, i.e. acetate buffer and the buffer containing 10?vol% of methanol, based on the thin-layer chromatography (TLC)-densitometry technique. Based on the unit weight of the actual amount of asiaticoside present in the specimens, the total amount of asiaticoside released from the fiber mat specimens was lower than that from the film counterparts while, based on the unit weight of the specimens, an opposite trend was observed.     

Amelioration of hyperglycemia,hyperlipidemia, oxidative stress and inflammation in steptozotocin-induced diabetic rats fed a high fat diet by riceberry supplement

Dark purple riceberry bran contains a higher dietary fiber and antioxidant compounds than unpigmented rice bran. Riceberry supplement (RB) was used to evaluate the effects on biochemical parameters, skeletal muscle glucose transporter 4 (GLUT4), oxidative stress and inflammation in a streptozotocin (STZ)-induced diabetes rat. To elucidate the effects were due to dietary fiber supplementation and/or bioactive components, equivalent amounts of dietary fiber present in RB were also fed to STZ-induced diabetic rats. Diabetes Sprague–Dawley rats (non-FBG ? 16.65 mM) were randomly divided into five groups: DM fed a high fat (HF) diet, DM-RB1 fed 5% RB, DM-RB2 fed 41% RB, DM-F1 fed 0.6% fiber and DM-F2 fed 5% fiber. After 12 weeks, significant improvement of BG, insulin, HbA1_C, IPGTT and GLUT4 levels were observed in DM-RB1 and DM-RB2 groups. Hyperlipidemia was significantly improved in DM-RB2 and DM-F2 groups. Oxidative stress (TBARS), antioxidant enzymes (SOD, CAT, and GPx), antioxidant capacity (ORAC), pro-inflammation cytokine (TNF-α and IL-6) were improved in DM-RB1 and DM-RB2 groups. Improvement of pancreas and spleen histology was found in DM-RB1 and DM-RB2 groups. These indicate the potential of RB to improve hyperglycemia and hyperlipidemia conditions as well as alleviate oxidative stress and inflammation.