TOCOPHEROLS AND PHOSPHOLIPIDS ENHANCE THE OXIDATIVE STABILITY OF BORAGE AND EVENING PRIMROSE TRIACYLGLYCEROLS

The effect of individual phospholipids and tocopherols as well as their combinations on the oxidative stability of borage and evening primrose triacylglycerols (TAG) was investigated. Based on conjugated dienes (CD) and 2-thiobarbituric acid reactive substances (TBARS) formed in borage and evening primrose TAG, the antioxidant effectiveness of phosphatidylcholine (PC), was higher than that of phosphotidylethanolamine (PE) in borage TAG while the reverse was observed for evening primrose TAG. Meanwhile, a synergistic effect between tocopherols and phospholipids in both borage and evening primrose TAG was noted. The most effective combination in borage TAG was that of PC and α-tocopherol, while PE with α-tocopherol exerted the best effects in evening primrose TAG. Therefore, the antioxidant effectiveness of phospholipids may vary depending on their fatty acid composition, nature of the functional groups and the chemical composition of the lipid system in which they are examined. The results also demonstrate the importance of minor components of vegetable oils on their oxidative stability.     

INFLUENCE OF ANTE-MORTEM GLYCOLYSIS AND DEPHOSPHORYLATlON OF HIGH ENERGY PHOSPHATES ON BEEF AGING AND TENDERNESS

The effects of ante-mortem glycolysis, and rapid post-mortem drop in pH and dephosphorylation of high energy phosphates on beef tenderness were studied using twelve major muscles from carcasses having post-slaughter pH values in the ranges 6.7–7.1 and 5.8–6.2. In muscles which had low post-slaughter pH, dephosphorylation of high energy phosphates and pH changes were complete in about 16 hr postmortem. On the other hand, these changes continued for up to 32 hr post-mortem in muscles which had high post-slaughter pH. Muscles with high post-slaughter pH values required about 7 days of aging to attain maximum tenderness, and were more tender than the corresponding low post-slaughter pH muscles aged for the same length of time or longer. Results suggest that the simple measurement of pH within 1 hr after slaughter may be useful for assessing the required aging time and the ultimate tenderness of beef.     

THE WEDGE FRACTURE TEST A NEW METHOD FOR MEASUREMENT OF FOOD TEXTURE

The fracture properties of foods are relevant to texture but can be difficult to measure because of limitations of size or shape. Many established engineering tests for the measurement of crack growth and unstable propagation of cracks require specific test geometries, sizes and compliances of the specimen. With food materials this is rarely possible. The wedge penetration technique can usefully be adapted to foods to determine fracture parameters of brittle and semi-brittle foods such as moderately hard cheeses and raw and cooked fruits and vegetables.     

EFFECT OF TEMPERATURE DURING POST-MORTEM GLYCOLYSIS AND DEPHOSPHORYLATION OF HIGH ENERGY PHOSPHATES ON POULTRY MEAT TENDERNESS

SUMMARY– Tests made on pectoralis major muscles having post-slaughter pH values ranging between 6.1–7.0, indicated that holding poultry meat at 30 and 37°C during the onset of rigor mortis caused toughness. This toughening effect of high temperature appeared to occur when the pH level of the meat dropped from a value of about 6.3 to its ultimate low value and the adenosine triphosphate content dropped below 40% of its initial concentration. Holding temperatures at 10, 15 and 25°C during the onset of rigor mortis, or cooling to 15°C before the pH value dropped to about 6.3 produced more tender meat. After completion of post-mortem glycolysis and dephosphorylation of high energy phosphates, high temperature had no deleterious effect on tenderness. These results indicate that dephosphorylation of adenosine triphosphate at high temperature affects the mode or extent of stiffening of the muscular tissue and prevents tenderization.     

Characterization of 3D microstructure,thermal conductivity,and heat flow of cement-based foam using imaging technique

This study presents the results of the 3D microstructure, thermal conductivity, and heat flow in cement-based foams and examines their changes with a range of densities. Images were captured using X-ray micro computed tomography (micro-CT) imaging technique on cement-based foam samples prepared with densities of 400, 600, and 800 kg/m³. These images were later simulated and quantified using 3D data visualization and analysis software. Based on the analysis, the pore volume of 11000 µm³ was determined across the three densities, leading to optimal results. However, distinct pore diameters of 15 µm for 800 kg/m³, and 20 µm for 600 and 400 kg/m³ were found to be optimum. Most of the pores were spherical, with only 10% appearing elongated or fractured. In addition, a difference of 15% was observed between the 2D and 3D porosity results. Moreover, a difference of 5% was noticed between the experimentally measured thermal conductivity and the numerically predicted value and this variation was constant across the three cast densities. The 3D model showed that heat flows through the cement paste solids and with an increase in porosity this flow reduces.     

Oblique propagation of nonlinear ion-acoustic cnoidal waves in magnetized electron–positron–ion plasmas with nonextensive electrons

Theoretical investigation of nonlinear electrostatic ion-acoustic cnoidal waves(IACWs) is presented in magnetized electron–positron–ion plasma with nonextensive electrons and Maxwellian positrons. Using reductive perturbation technique, Korteweg–de Vries equation is derived and its cnoidal wave solution is analyzed. For given plasma parameters, our model supports only positive potential(compressive) IACW structures. The effect of relevant plasma parameters(viz., nonextensive parameter q, positron concentration p, temperature ratio σ,obliqueness l_3) on the characteristics of IACWs is discussed in detail.     

Energy and flux measurements of laser-induced silver plasma ions by using Faraday cup

Silver(Ag)plasma has been generated by employing Nd∶YAG laser(532 nm,6 ns)laser irradiation.The energy and flux of ions have been evaluated by using Faraday cup(FC)using time of flight(TOF)measurements.The dual peak signals of fast and slow Ag plasma ions have been identified.Both energy and flux of fast and slow ions tend to increase with increasing irradiance from 7 GW cm-2 to 17.9 GW cm-2 at all distances of FC from the target surface.Similarly a decreasing trend of energies and flux of ions has been observed with increasing distance of FC from the target.The maximum value of flux of the fast component is 21.2×1010cm-2,whereas for slow ions the maximum energy and flux values are 8.8 keV,8.2×1012 cm-2 respectively.For the analysis of plume expansion dynamics,the angular distribution of ion flux measurement has also been performed.The overall analysis of both spatial and angular distributions of Ag ions revealed that the maximum flux of Ag plasma ions has been observed at an optimal angle of～15°.In order to confirm the ion acceleration by ambipolar field,the self-generated electric field(SGEF)measurements have also been performed by electric probe;these SGEF measurements tend to increase by increasing laser irradiance.The maximum value of 232 V m-1 has been obtained at a maximum laser irradiance of 17.9 GW cm-2.     

Measuring Skeletal Muscle Fiber Width or Diameter: Variance Within and Among Methods

A bovine longissimu; dorsi muscle was divided into anterior and posterior pieces, half of each piece was roasted at 140°C to 70°C. “Widths” or “diameters” of fibers from each position (anterior, posterior) and treatment (raw, cooked) were measured by three methods: A, width of separated fibers on a longitudinal plane; B, width of fibers in ongitudinal sections; and C, fiber diameter calculated from the area of fibers in cross sections. Bartlett's test for homogeneity of variance indicated greater (P<0.05) variance among observations by method A than by methods B or C; position-treatment variances were larger (P<0.05) for method A than for B or C.     

电站低温给水系统腐蚀产物生成过程研究

燃煤电站汽水系统中低温给水部件由于流动加速腐蚀产生大量腐蚀产物,这些腐蚀产物随工质在整个汽水系统中迁徙,严重影响了机组的运行安全及寿命。基于质量平衡方程,建立了腐蚀产物的生成模型,从3种不同角度分析了金属氧化层孔隙率、铁在工质中的扩散系数和工质pH值等对腐蚀速率的影响。结果显示：腐蚀速率分别与前两者成正比关系,而与工质的pH值成反比关系。给水加氧处理可使金属氧化膜的孔隙率明显降低,而管道布置越复杂、管道表面越粗糙,铁在工质中的扩散系数越大。因此,燃煤电站在实际运行中,可通过管道结构优化,选择最佳给水处理方式,在最佳pH值和溶氧量条件下抑制流动加速腐蚀,减少腐蚀产物的产生。     

Exploring Chemical Substructures Essential for hERG K+ Channel Blockade by Synthesis and Biological Evaluation of Dofetilide Analogues

In this study we followed a new approach to analyze molecular substructures required for hERG channel blockade. We designed and synthesized 40 analogues of dofetilide ( 1 ), a potent hERG potassium channel blocker, and established structure–activity relationships (SAR) for their interaction with this important cardiotoxicity‐related off‐target. Structural modifications to dofetilide were made by diversifying the substituents on the phenyl rings and the protonated nitrogen and by varying the carbon chain length. The analogues were evaluated in a radioligand binding assay and SAR data were derived with the aim to specify structural features that give rise to hERG toxicity.