Synthesis of thin alpha alumina platelets with a large aspect ratio

Since α-Al₂O₃ platelets with small thickness and large aspect ratio are needed in various applications, it is of great importance to control their morphology. In the present work, we successfully fabricated α-Al₂O₃ platelets with small average thickness below 100 nm and large average aspect ratio above 100 by molten-salt method, using Al₂(SO₄)₃ as the raw material, eutectic mixtures of Na₂SO₄ and K₂SO₄ as the molten salt as well as TiO₂ and SiO₂ as the co-dopants. The effects of calcination temperature, seeds amount and seeds morphology on the final morphology of α-Al₂O₃ platelets were investigated. The growth mechanism of the α-Al₂O₃ platelets in molten salt was also discussed. A new growth mechanism of α-Al₂O₃ platelets in molten salt has been proposed, which is different from previous mechanism but can explain the two different phenomena caused by seeds with different sizes and quantity.     

液相化学还原法制备片状银颗粒的影响因素及研究进展

片状银颗粒具有独特的电性能、光性能等优良性能,近年来,在各个领域引起了广泛的关注.液相化学还原法具有反应条件可控、利于量产的优势,被广泛用于片状银颗粒的制备中.本文首先介绍了在液相化学还原法中片状纳米银颗粒的生长机理,分析了各反应条件,例如pH值、晶种、表面活性剂、硝酸银浓度等对生成片状银颗粒的影响.综述了国内外利用液相化学还原法制备片状银颗粒的研究进展;针对研究中存在的一些问题,展望了下一步的研究方向.     

沙枣种子油的超声波辅助提取及理化性质分析

本试验探讨了超声波功率、提取温度、提取时间和料液比对超声波辅助提取沙枣种子油的影响.在单因素试验基础上,进行了正交试验.结果表明,各因素对超声波辅助提取沙枣种子油的影响次序为:提取温度＞提取时间＞超声波功率＞料液比;最优工艺参数为:超声波功率120 W、提取温度30℃、提取时间30 min、料液比1∶6,沙枣种子油提取率达26.07％.气质联用分析结果表明,超声提取的沙枣种子油组成脂肪酸主要是亚油酸49.12％、油酸37.26％、棕榈酸3.91％和硬脂酸1.63％,此外还含有少量的二十碳烯酸0.64％、二十酸0.22％和木焦油酸0.23％.     

Abelmoschus esculentus (L.) Moench. and Abelmoschus moschatus Medik: Seeds production and analysis of the volatile compounds

Nine accessions of Abelmoschus esculentus (L.) Moench. and three of Abelmoschus moschatus Medik were both grown in Central Italy for the evaluation of the production of seeds. Furthermore, the volatiles emitted by the mature seeds were sampled by mean of SPME. Seventy compounds were detected in the headspace of the seeds of A. esculentus. The principal constituents common to all the nine accessions were isopentyl 2-methyl butanoate (24.5–59.1%) and heptanoic acid 2-methylbutyl ester (6.6–13.5%). In the headspace around the seeds of A. moschatus 93 components were detected. Among the main volatiles shared by the three accessions, n-tridecane (1.5–26.9%), isopentyl 2-methyl butanoate (0.2–14.3%) and decanal (1.6–5.7%) should be mentioned. Many differences were present in the volatiles emitted by the various accessions and between the two Abelmoschus species.     

Contents of Carotenoids, Tocopherols and Sterols in Acacia cyanophylla Seed Oils

Seeds from 12 Acacia cyanophylla ecotypes, harvested in Tunisia, were examined for their seed oil contents of carotenoids, tocopherols and phytosterols. The average carotenoid content (lutein and zeaxanthin) was ca. 102 mg kg^?1 of total extracted lipids. Lutein (ca. 97 mg kg^?1 of total extracted lipids) was usually more abundant than zeaxanthin (ca. 5 mg kg^?1 of total extracted lipids). The mean total tocopherol content was ca. 704 mg kg^?1 of total extracted lipids. The main isomer was α‐tocopherol, with more than 75 % of total tocopherols (ca. 528 mg kg^?1 of total extracted lipids), followed by γ‐tocopherol (ca. 168 mg kg^?1 of total extracted lipids) and δ‐tocopherol (ca. 86 mg kg^?1 of total lipids). High levels of phytosterols (ca. 7.8 g kg^?1 of total extracted lipids) were detected, among which β‐sitosterol was the most abundant (47 %). All these results highlight the richness of carotenoids, tocopherols and sterols in A. cyanophylla seed oil, and imply that this species might constitute a potential resource for the development of functional foods.     

On the Analysis of Drying Process

Drying plays an important role in processing agricultural grains/seeds, chemicals, and other materials. In the present work, drying process has been analyzed taking published data on different grains and seeds such as rapeseed, sunflower, soybean, corn, paddy, and wheat. Mathematical expressions have been established for important drying parameters such as critical moisture content, drying rates, time required to reach critical moisture content, total drying time, and diffusivity as function of drying air temperature. The expressions involve a coefficient parameter and an exponential function of drying air temperature, Aexp(- E/RT_g),and interestingly it is shown that the same functional form with same Es can correlate the different relevant drying parameters. The coefficient parameters As and Es are decided by drying materials and drying process, and the values have been derived for different grains/seeds. The correlations are useful in analyzing the drying process.     

Effect of Oxidative Treatment on Corn Seed Germination Kinetics

Corn seeds were treated with high purity oxygen ([O₃]?=?0 g/m³) and oxygen mixed with ozone ([O₃]?=?20 g/m³) during 6.8 or 20.5 minutes. Germination tests started immediately or 48 h after treatment. Effects of oxidative treatments on germination were determined by measuring seedlings and roots (>3 and?>20 mm) rate at 3, 4 and 5 days of germination test. Results obtained for treated seed samples were higher than for untreated ones. A faster start of germination was observed for treated samples. This early germination start led to a larger number of germinated seeds with longer roots at 4 and 5 days. Nevertheless, too long an ozone treatment seemed to be unfavorable for seed growth, whereas a short one seemed to be most beneficial.     

樟树叶、籽活性成分的研究进展

樟树是一种用途很广的树种,在我国资源非常丰富,药用价值和绿化价值非常高,引起了当前研究者的广泛关注。本文综述了樟树籽、叶化学成分组成、功能活性和现有的提取分离工艺等几个方面的研究现状。     

Environmental and Genetic Variation of Soybean Tocopherol Content Under Brazilian Growing Conditions

Information about the chemical composition of soybean cultivars (cvs) and environmental impact on their composition is important for processors and exporters to meet the demand of niche markets. Tocopherol composition (α, β, γ, δ, and total), was analyzed in seeds of 89 Brazilian soybean cultivars grown under fertile soil in Ponta Grossa, Paraná state, Brazil, in 2001. A large range of variability was observed: for α-tocopherol, 11 ppm (cv. Davis) to 191 ppm (cv. IPB-T); for β-tocopherol, 6 ppm (cv. IAC 1) to 64 ppm (cv. IPB-T); for γ-tocopherol, 304 ppm (BR62 Carla) to 1333 ppm (cv. Bienville); for δ-tocopherol, 174 ppm (cv. UFV 15) to 580 ppm (cv.IAS-5; and for total tocopherols, 561 ppm (cv. BRS62 Carla) to 1,983 ppm (cv. BR4-RC). For comparison of different growing locations, cv. MG/BR 46 Conquista was grown in 16 different locations of the Minas Gerais and Goiás states (Central Region, ca. 17° South latitude). Higher content of total tocopherol was found in Conquista, Uberaba, Sacramento, and Cerrado, while lower contents were observed in Alvorada, Iraí, and Uberlândia. In the South region (ca. 23° South latitude), the cultivar IAS 5, grown in 12 different locations of Paraná and São Paulo states, showed high total tocopherol content in Londrina, Pedrinhas, Ponta Grossa, and Nuporanga, and lower amounts in Cascavel, Pirassununga, Luiziana, and Morro Agudo. Tocopherol content in soybean seeds varied due to genetic differences as well as to the local environmental factors of different growing locations.