Further compositional analyses of flax: Mucilage,trypsin inhibitors and hydrocyanic acid

Registered Canadian cultivars of flax, and laboratory-prepared and commercially obtained samples of linseed meal (LM), were used to determine extract viscosity and mucilage, trypsin inhibitors and hydrocyanic acid (HCN) concentrations. The mucilage readily leached out from the seed coat (hull) fragments soaked in water, leaving behind pentagon-shaped cells that could be seen clearly in scanning electron micrographs. Extract viscosity significantly varied in the laboratory-prepared (23–48 cS) and commercially obtained (30–68 cS) samples of LM and may be used to obtain an indirect, qualitative estimate of flax mucilage. Mucilage was extracted from whole seed in 5.0–5.3% yields and contained 20–24% protein (about 10% ash and 30% total carbohydrates). Laboratory-prepared LM (raw) contained 42–51 units of trypsin inhibitor activity, commercially obtained samples, 14–37 units, and raw rapeseed and soybean meals, 99 and 1650 units, respectively. Picric acid tests (qualitative) showed only traces of HCN in ten cultivars of freshly ground flax. The acid silver nitrate titration procedure measured HCN quantitatively, but showed its presence only in three of the five cultivars investigated. HCN was conveniently measured by a colorimetric procedure (barbituric acidpyridine reaction), which may be used to screen flax cultivars. HCN content of flax was significantly influenced by environments (growth location and season) and, to a less extent, by cultivar.     

Natural Convection Drying at Low Temperatures of Previously Frozen Salted Meat

The drying of raw cured ham proceeds under natural convection. The aim of this work was to determine the effect of external resistance on the drying of frozen and salted Biceps femoris and Semimembranosus. Natural convection drying kinetics were obtained at 5, 10, 15, and 20°C. The D_e values obtained neglecting external resistance were underestimated. Activation energy, E_a, agreed with literature results. The use of a D_e value from literature and a calculated E_a allowed us to calculate D_e for the temperatures used in this study. The mass transfer coefficient (k) was estimated from a model taking external resistance and the calculated D_e into account. The k values agreed with the ones in literature; thus, under natural convection conditions, external mass transfer resistance must be considered.     

HAND BOOK OF DEHUMIDIFICATION TECHNOLOGY

The shrinkage of pork meat cylinders was measured and correlated with moisture content. Samples of different sizes were dehydrated under different drying conditions: forced convection (25°C and 0.6, 2.0, and 2.8 m/s) and natural convection (5, 10, 15, and 20°C). A linear relationship was found between the quotients R/R₀ and V/V₀ and the moisture content. This linear relationship was not found to be dependent on the size of the samples, their salt content, or drying conditions. For the experimental conditions in this study, water losses are responsible for shrinkage.     

傅里叶变换近红外光谱法应用于聚乙烯树脂的正己烷提取物分析

采用偏最小二乘法(PLS),建立了傅里叶变换近红外漫反射光谱法检测聚乙烯树脂正己烷提取物的数学模型。分析过程选择了最佳光谱预处理方法、谱区范围及主因子数,并使用内部交叉验证对模型进行验证。实验结果表明,当选择最小-最大归一化的光谱预处理方法,谱区范围7 501.8～6 097.9 cm-1和5 025.6～4 597.5 cm-1,主因子数8时定量模型的准确度最好,决定系数(R2)和均方差(RMSECV)分别为0.988和0.416,近红外测定值与标准方法测定值基本一致。对297种牌号共1 251个进口聚乙烯树脂正己烷提取物项目的普查结果表明,聚乙烯树脂正己烷提取物项目的总体安全性较低,属于进口聚乙烯需重点关注的安全卫生项目。     

微生物提高采收率作用机理研究

简要阐述了微生物提高采收率技术及其发展,微生物提高采收率的优势。结合室内与矿场实验,介绍了微生物提高采收率作用的机理,指出下一步应加强优秀菌种的筛选与培养,对利用微生物实现稠油的“冷采”进行更详细的研究,对微生物提高采收率建立一套理论体系和实用的数值模拟方法。     

Biological synthesis of bimetallic Au/Ag nanoparticles using Persimmon (<Emphasis Type="Italic">Diopyros kaki</Emphasis>) leaf extract

Persimmon (Diopyros kaki) leaf extract was used for the synthesis of bimetallic Au/Ag nanoparticles. Competitive reduction of Au³⁺ and Ag⁺ ions present simultaneously in solution during exposure to Persimmon leaf extract leads to the formation of bimetallic Au/Ag nanoparticles. UV-visible spectroscopy was monitored as a function of reaction time to follow the formation of Au/Ag nanoparticles. The synthesized bimetallic Au/Ag nanoparticles were characterized with energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). SEM images showed that large Au/Ag particles of 50–500 nm were formed with some cubic structure, while pure Ag particles obtained by reduction of only Ag+ ion were smaller with diameter of 15–90 nm and predominantly spherical. The atomic Ag contents of the bimetallic Au/Ag nanoparticles from EDS and XPS analysis were 36 and 71 wt%, respectively, suggesting that bimetallic Au core/Ag shell structure was formed by competitive reduction of Au³⁺ and Ag+ ions with Persimmon leaf extract. This work was presented at 13 ^th YABEC symposium held at Seoul, Korea, October 20–22, 2007.     

粗制硫酸铝萃取除铁工艺的研究

本文利用自制的萃取剂Ａ,对粗制硫酸铝溶液〔１〕中的萃取除铁效率进行了实验研究,并探讨了萃取剂的再生方法和适宜条件。实验结果表明：使用萃取剂Ａ,对粗制硫酸铝溶液萃取二次,可使２８００ｐｐｍ 的铁减少到３０ｐｐｍ 以下,达到无铁硫酸铝的要求,而铝几乎不损失。对使用过的萃取剂以２．７％ 的硫酸溶液反萃取二至三次后,再通过水洗,碱洗,水洗,即实现再生,可以循环使用。     

基于BAS-BP模型的轴承剩余使用寿命预测

为有效评估轴承退化趋势,提高设备健康管理的智能化,提出一种基于BAS-BP模型的轴承剩余使用寿命预测方法。提取轴承全生命周期振动信号的时域和频域特征,构建18维退化特征;为提高神经网络的预测精度,采用天牛须搜索算法对初始权重和阈值进行优化,建立BAS-BP预测模型;通过在公开数据集上验证该模型的有效性。结果表明：所提模型可对轴承剩余寿命进行有效预测且精度较高。     

De electricitatis catholici musculari - Concerning the electrical properties of muscles, with emphasis on meat quality

This study aims to explore the potential of evoked non-invasive surface electromyography (SEMG) analysis, in predicting meat quality traits in livestock. Evoked SEMG is a system that records, transdermally, electrical signals generated in muscle fibres upon external stimulation. These signals are reported as compound muscle action potentials (CMAP). CMAP parameters of LD correlated negatively and significantly to ultimate pH (pH 24 h) at day 61, but not at day 153 after birth, and a similar albeit positive correlation was observed for muscle glycogen content. Muscle glycogen content and pH 24 h correlated negatively in LD and BF. Negative significant correlations between CMAP parameters and shear force were found in LD at day 153 after birth, which might, in the range of the recording electrodes, reflect the combined effect of large cross-sectional area fibres and reduced perimysium content per unit volume of muscle. The fact that correlations between CMAP characteristics and quality traits of both metabolic and non metabolic origin could be established, warrants a fuller investigation of this method in terms of its potential as a predictive tool for meat quality traits in live animals.     

Effects of previous diet and duration of soybean oil supplementation on light lambs carcass composition, meat quality and fatty acid composition

Forty Merino Branco ram lambs were used to study the effects of initial diet and duration of supplementation with a conjugated linoleic acid (CLA) promoting diet, on carcass composition, meat quality and fatty acid composition of intramuscular fat. The experimental period was 6 weeks. The experimental design involved 2 initial diets (commercial concentrate (C); dehydrated lucerne (L)), and 2 finishing periods (2 and 4 weeks) on dehydrated lucerne plus 10% soybean oil (O). Data were analysed as a 2 × 2 factorial arrangement with initial diet and time on finishing (CLA promoting) diet as the main factors. The lambs were randomly assigned to four groups: CCO; COO; LLO; LOO according to the lamb’s diet fed in each period.Lambs initially fed with concentrate showed higher hot carcass weights (11.2 vs 9.6 kg) than lambs fed initially with lucerne. The increase of the duration of finishing period reduced the carcass muscle percentage (57.4% vs 55.5%) and increased the subcutaneous fat percentage (5.67% vs 7.03%). Meat colour was affected by initial diet. Lambs initially fed with concentrate showed a lower proportion of CLA (18:2cis-9, trans-11 isomer) (0.98% vs 1.38% of total fatty acids) and most of n−3 polyunsaturated fatty acids than lambs initially fed with lucerne. Initial diet did not compromise the response to the CLA-promoting diet and the proportion of 18:2cis-9, trans-11 in intramuscular fat increased with the duration of time on the CLA-promoting diet (1.02% vs 1.34% of total fatty acids).