Effects of three conventional drying methods on the lipid oxidation,fatty acids composition,and antioxidant activities of walnut (Juglans regia L.)

Three walnut (Juglans regia L.) drying methods (sun drying, direct oven drying, and intermittent oven drying) were employed, and the consequent changes in lipid oxidation attributes, such as acid value (AV), peroxide value (POV), saponification value (SV), fatty acid composition, and antioxidant activity [including reducing power, superoxide anion scavenging activity, 1,1-diphenyl-2-picrylhydrazyl free radical scavenging activity (DPPH), lipoxygenase (LOX) activity, total phenols content (TPC), and total flavonoids content (TFC)] were investigated in this study. Sun drying resulted in the highest AV, POV, and SV, followed by direct oven drying and intermittent oven drying. Antioxidant activities and related compounds, TPC and TFC, were initially increased and then declined during drying, and a significant correlation was found between antioxidant activity and TPC and TFC. The LOX activities of all samples showed an increasing trend, although those of the sun-dried samples were the lowest. The walnuts dried with the intermittent oven drying method contained more linoleic acid than those dried by direct oven drying. Overall, intermittent oven drying appears to be a promising strategy for fresh walnut drying.     

Effect of Industrial Chemical Refining on the Physicochemical Properties and the Bioactive Minor Components of Peanut Oil

The effect of the industrial chemical refining process on the physicochemical properties, fatty acid composition, and bioactive minor components of peanut oil was studied. The results showed that the moisture and volatile matter content, acid value, peroxide value, and p‐anisidine value were significantly changed (P < 0.05) after the complete refining process. No significant variation (P > 0.05) in the iodine value was observed among all the peanut oil samples. Similar changes were observed in the DPPH radical scavenging activity and the total tocol content during chemical refining. In addition, chemical refining did not have much effect on the fatty acid composition, except for certain changes of several individual fatty acids. Moreover, the chemical refining resulted in 23.6, 23.1, and 9.5 % losses of squalene, total phytosterols, and total tocols (α, β, γ, δ‐tocopherols and α, β, γ, δ‐tocotrienols), respectively. The degumming–neutralization step caused the greatest overall reduction of these bioactive minor components. However, the concentrations of α‐tocotrienol and γ‐tocotrienol increased after full refining. Furthermore, chemical refining slightly changed the relative proportions of individual phytosterols and individual tocols.     

Seed Oils of Five Black Tartary Buckwheat Cultivars with Biochemical Characterization and Antioxidant Properties

Black tartary buckwheat oils (BTBOs) were extracted from five major industrial tartary buckwheat cultivars grown under similar agronomical activities and environmental conditions. These oils were characterized for the bioactive compounds containing fatty acids, β‐carotene, lutein, α‐, β‐, δ‐ and γ‐tocopherol, and for their antioxidant properties. The total tocopherol contents that were obtained ranged from 704.66 to 1156.19 mg/kg, with γ‐tocopherol (588.98–977.91 mg/kg) as the main component. The concentration of lutein ranged from 253.14 to 429.63 mg/kg, which was almost ten times higher than that of β‐carotenoid (46.71–69.2 mg/kg), indicating that black tartary buckwheat seed oils were a good source of lutein. The predominant fatty acids were unsaturated oleic acid (C18:1) (35.27–40.61 %) and linoleic acid (C18:2) (38.25–42.90 %). Excellent values of 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH), diammonium salt (ABTS) radical scavenging activities were obtained and the highest oxygen radical absorbance capacity (ORAC) value of 13.89 mmol Trolox equiv/g oil was detected in the variety of Chuanqiao No. 1, which was clearly separated by principal component analysis (PCA) on the basis of the highest content of tocopherols and carotenoids. Moreover, the correlation analysis showed that tocopherols and carotenoids were the major contributors to the antioxidant activities of the BTBOs. This study demonstrates that lipophilic extraction in the tartary buckwheat seed contains many interesting bioactive compounds, which are beneficial for human health.     

Composition of Rice Bran Stearin from Various Refineries Across China

In this study, we evaluated the composition of rice bran stearin (RBS) from various refineries across China. Here, we report the physicochemical parameters of RBS. The slip melting point ranged from 20.8 to 35.3 °C. The free fatty acid content (0.05–0.27 %) and peroxide value (0.34–3.70 mequiv oxygen/kg) was quite low, indicating that the RBS was of good quality. The iodine value ranged from 85.8–102.9 g/100 g, indicating a high unsaturated bond content. There was a significant difference in the unsaponifiable matter content (1.20–3.87 %) among RBS samples. The oxidative stability index (OSI) ranged from 0.56 to 5.85 h. The palmitic acid content in RBS refined by molecular distillation was significantly higher than the RBS that was refined physically and chemically. The major triacylglycerol was LLO/OLL, PLL/LPL, OLO, PLP, OOO and POO (L, linoleic acid; O, oleic acid; P, palmitic acid). RBS contained high levels of micronutrients, including total tocopherols (23.3–117.9 mg/100 g), oryzanol (0.1–2.1 %), and total sterols (682.9–1787.3 mg/100 g). Moreover, three different kinds of solid fat curves were distinguished. The results presented here are probably the first report regarding RBS on an industrial scale, meanwhile the potential utilization of RBS is discussed.     

电解液组成对CO_2电化学还原效率的影响

为了考察电解液组成(溶剂和支持电解质)对CO_2电还原效率的影响,以金属银为工作电极,在三电极电解槽中进行了恒电位电解及循环伏安扫描实验。结果表明:相比于二甲基甲酰胺(DMF)和甲醇,用乙腈作溶剂时产物CO法拉第效率最高;强酸作为阳极液支持电解质可以降低CO_2还原过电位并提高CO部分电流密度;离子液体作为阴极液支持电解质可以全面提高CO_2还原效率。研究不同离子液体的催化行为,发现离子液体中阳离子部分对CO部分电流密度的影响比阴离子的影响更明显,进一步证实了咪唑阳离子对还原CO_2起主要催化作用。     

Mathematical simulation of wet spinning coagulation process: Dynamic modeling and numerical results

A dynamic model of polymer wet spinning coagulation process is proposed in this article. The model is based on the double diffusion phenomenon, phase separation process, continuity balance, and momentum balance of the entire coagulation process. The uniqueness of the model lies in its dynamic feature. The model can simulate the system's dynamic response to variations in system inputs/parameters. Steady‐state system solutions can also be produced as the long‐time solutions of the dynamic model; a settling time can be observed at the same time. This paper employs a computationally efficient method of lines numerical algorithm for solving the dynamic model. A simulation experiment on a selected non‐solvent‐solvent‐polymer ternary system is carried out to verify the model as well as the numerical method. The dynamic simulation results are analyzed and discussed. At the end of the article, h‐refinement and p‐refinement are used to confirm the spatial convergence of the numerical solutions. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3432–3440, 2016     

Structure and Microwave Dielectric Behavior of A‐Site‐Doped Sr(1−1.5x)CexTiO3 Ceramics System

The ion valence state, phase composition, microstructure, and microwave dielectric properties of Sr_(1?1.5x)Ce_xTiO₃ (x = 0.1–0.67, SCT) ceramics were systematically investigated. Sr_(1?1.5x)Ce_xTiO₃ ceramics were produced with gradual structural evolution from a cubic to a tetragonal and turned to an orthorhombic structure in the range of 0.1 ≤ x ≤ 0.67. Above a critical Ce proportion (x = 0.4), microstructural changes and normal grain growth initially occurred. On the basis of chemical analysis results, the reduction of Ti⁴⁺ ions was hastened by tetravalent ions (Ce⁴⁺). By contrast, this reduction was inhibited by trivalent ions (Ce³⁺). The observed dielectric behavior was strongly influenced by phase composition, oxygen vacancies (), and defect dipoles, namely, () and (). Temperature stable ceramics sintered at 1350°C for 3 h in air yielded an intermediate value of dielectric constant (ε_r = 40), with the smallest reported value of temperature coefficient of resonant frequency (τ_f = +0.9 ppm/°C), and quality factor (Q × f = 5699 GHz) at x = 0.6.     

Chemical Composition and Physical Properties of High Oleic Safflower Oils (Carthamus tinctorius,Var. CW88-OL and CW99-OL)

Chemical composition and physical properties of CW88‐OL and CW99‐OL cultivars of high oleic safflower seeds and their hexane‐extracted oils were determined. Dry‐based seed composition of CW88‐OL and CW99‐OL was: moisture = 4.29 and 4.23 %, oil = 42.29 and 46.44 %, Crude protein = 20.94 and 16.41 %, neutral detergent fiber = 28.11 and 28.49 %, ash = 1.55 and 2.01 %, phosphorus content = 2033 and 3995 mg/kg, respectively. Major fatty acids in oils were ~78 % oleic (O), ~13 % linoleic (L), ~5 % palmitic (P) and ~2 % stearic (St) acids, for both cultivars. The main triacylglycerols were OOO (~50 %), OOL (~20 %), SOL + OPO (~10 %), and LLP (~5 %). The oil composition of CW88‐OL and CW99‐OL in main minor components was: α‐tocopherol = 582 and 551 mg/kg, total sterols = 3996 and 3362 mg/kg, phospholipids = 22 and 21 mg/kg and wax content = 70 and 74 mg/kg. For both cultivars, density and viscosity of the oils between 25 and 55 °C varied from 903.4 to 912.6 kg/m³ and 63 to 23 mPa.s showing linear and exponential behaviors, respectively. The refractive index was 1.4694. The CIELab color parameters were: 89.69 and 89.53 (L*), ?3.72 and ?3.07 (a*), and 47.28 and 47.78 (b*) (CW88‐OL and CW99‐OL, respectively). Thus, the high oil content of the seeds and nutritional quality of the oil accompanied by low levels of waxes and phospholipids makes the cultivars studied promising for producers and consumers.     

长期运行老化导线表面状态及电晕特性变化研究

目的研究某地区长期运行的导线的表面状态、表面成分以及电晕特性,分析老化导线的表面特性变化规律。方法采用场发射扫描电子显微镜分析导线表面物质成分及分布状态,采用紫外成像仪对施加不同电压等级下电晕放电光子数进行计数,表征其放电的强弱程度。结果导线表面物质成分中非金属元素主要是氧、碳、硫、硅和少量的磷,金属元素主要是铁、铝、钙、钠、镁、钾,且表面状态与所处环境有关;长期运行导线表面在相同放电电压下放电光子数比新导线多。结论污秽颗粒、不规则的表面结构是长期运行的导线在正常运行电压下发生电晕放电的根源,导线表面的污秽成分与所处地区有关,导线表面凹凸不平会导致其起晕电压比新导线要小。导线的运行年限对表面状态和电晕放电特性有影响。