Microflora, Sensory and Exudate Changes of Vacuum- or Nitrogen-Packed Veal Chucks Under Different Storage Conditions

Apart from increases in microflora number at —4°C under vacuum and at 0°C under nitrogen, there was in general no significant (P gt; 0.05) differences in numbers of lactobacilli, psychrotrophs, aerobes and anaerobes between vacuum- and nitrogen-packed veals during 49 days of storage at 3 and 7°C, regardless of dark and lighted displays. The initial psychrotrophs consisted primarily of Pseudomonas putida (> 72%) but by day 49 Lactobacillus spp. comprised at least 64% of the total in both atmospheres. Sensory and exudate data showed a highly significant (P < 0.05) difference due to the effect of storage time and temperature above 0°C. Nitrogen-packed veals exhibited a lower incidence of greening and exudate loss at 0, 3 and 7°C. Light generally had important effects on off-odor and exudate loss, irrespective of package types.     

开闸式异重流前峰行进规律:数值求解

本文首先以数值方法求得开闸式异重流前峰行进规律。数值求解基于重在化群（ＲＮＧ）ｋ－ε湍流应力封闭模式,能合理反映异重流的过渡性局部湍流特征,结果与实验相符,表明开闸式湍动重流的前峰行进有两个阶段,先是坍塌段,峰速不变,后是自相似段,峰这随时间以－１／３次规律递减。     

Electrical Conductivity of Polycrystalline A12O3 Doped with Silicon

Direct current conductivity was measured for polycrystalline Alz03 doped with silicon, which is found to act as a single donor, the donor level lying ∼165 kJ/mol (∼1.7 eV) below the conduction band. Silicon in excess of the solubility limit (∼220 ppm at 1500°C, 300 ppm at 1600°C) is present as a glassy aluminosilicate second phase. Silicon dissolved in Al₂O₃ tends to segregate at grain boundaries.     

Suspension Processing of Al2O3/SiC Whisker Composites

Homogeneous Al₂O₃ powder/SiC whisker compacts were prepared by suspension processing. By optimizing the conditions for particle/whisker codispersion, castable suspensions could be prepared at total-solids concentrations 50 vol%. Green bodies with high relative density (∼66% to 70%) were obtained with SiC whisker contents in the range of 5 to 30 vol%. Although densification was severely inhibited by the SiC whiskers, significantly higher sintered densities were obtained by suspension processing compared to dry processing.     

固体氧化物燃料电池离子- 电子混合传导性Ni/ScSZ 燃料极的制备以及性能分析

在薄膜固体氧化物燃料电池中,为增加发生电化学反应的三相界面面积,燃料极和空气极通常制备成离子-电子混合传导性质的多孔形态。该研究将燃料极电化学反应(氢氧化反应)的催化剂——镍(Ni)和氧离子传导性好的氧化钪稳定的氧化锆(ScSZ)混合制备成离子-电子混合传导燃料极。实验结果显示,与纯 Ni 燃料极相比,所制备的 Ni/ScSZ 燃料极因其三相界面面积的增加,可显著降低极化电阻,但同时欧姆电阻也显著增加,从而最终导致燃料电池单池性能总体下降。     

MODELING OF COPPER ION REMOVAL FROM AQUEOUS SOLUTIONS USING MODIFIED SILICA BEADS

Silica beads, containing 2-hydroxy-5-nonylacetophenoneoximc (LIX84) were prepared in order to examine the removal of copper ions from aqueous waste solutions. The process for copper ion removal using the modified silica beads was mathematically modeled using both a non-equilibrium model and an equilibrium model. The external mass transfer coefficient and effective diffusivity inside the bead pore were estimated by matching the experimental data and predicted values from the model, and the results were compared. The results of the two models were similar and in good agreement because of the relatively faster reaction rate than mass transfer rate. Sensitivity analyses showed that the external mass transfer has more influence on the copper ion removal system because of hydrophobic effects.     

真空热压铝和铜的固态连接(英文)

在温度623~923K下采用真空热压扩散连接铝和铜,具体工艺为在预置温度下,变形率为0.2mm/min时热压缩10min,再在炉冷过程中,以0.2mm/min成型10min。通过界面分析可以看出,合适的扩散连接温度为823K,在扩散过程中产生了3种主要的金属间化合物层,分别为Al2Cu、AlCu+Al3Cu4和Al4Cu9。3种化合物层的局部硬度分别为(4.97±0.05)、(6.33±0.00)、(6.06±0.18)GPa。     

PREDICTING RELATIVE HUMIDITY IN MODIFIED ATMOSPHERE PACKAGING SYSTEM CONTAINING BLUEBERRY AND MOISTURE ABSORBENT

A modified respiration-transpiration model was developed to predict the relative humidity in modified atmosphere packaging system containing fresh produce and moisture absorbent. The model is based on heat and mass balances accounting for the respiratory and transpiratory behavior of the fresh produce, the transport phenomena across the package, and the moisture sorption behavior of the absorbent. A set of experiments was conducted to obtain the parameter values that were necessary for generating model predictions. Another set of experiments was conducted using model packages containing blueberries and moisture absorbents Sanwet and xylitol to obtain experimental data under various conditions, including different weights of blueberries, types of absorbers, weights of absorbers, and temperatures. In general, the model predictions agree well with the experimental data, except the model sometimes exaggerates the effects of the absorbent in the initial period (<10 h).     

Retinyl Palmitate Isomers in Skim Milk During Light Storage as Affected by Ascorbic Acid

Effects of ascorbic acid addition on the contents of retinyl palmitate isomers in skim milk treated with or without 3 mg/mL added riboflavin were studied during storage for 30 h under fluorescent light. Light illumination induced the reduction of all-trans-retinyl palmitate and 13-cis isomer, but promoted the production of 9-cis isomer in the skim milk. Riboflavin increased the reduction of all-trans-retinyl palmitate, but decreased the formation of 9-cis isomer in lightstored skim milk. The addition of ascorbic acid greatly inhibited the light-induced reduction of all-trans-retinyl palmitate and 13-cis isomer in skim milks. Ascorbic acid also greatly increased the formation of 9-cis-retinyl palmitate in skim milks during light storage.