Trans-10 18:1 in ruminant meats: A review

Trans (t) fatty acids (TFA) from partially hydrogenated vegetable oils (i.e., industrial trans) have been phased out of foods in many countries due to their promotion of cardiovascular disease. This leaves ruminant-derived foods as the main source of TFA. Unlike industrial TFA where catalytic hydrogenation yields a broad distribution of isomers, ruminant TFA are enzymatically derived and can result in enrichment of specific isomers. Comparisons between industrial and ruminant TFA have often exonerated ruminant TFA due to their lack or at times positive effects on health. At extremes, however, ruminant-sourced foods can have either high levels of t10- or t11-18:1, and when considering enriched sources, t10-18:1 has properties similar to industrial TFA, whereas t11-18:1 can be converted to an isomer of conjugated linoleic acid (cis(c)9,t11-conjugated linoleic acid), both of which have potential positive health effects. Increased t10-18:1 in meat-producing ruminants has not been associated with negative effects on live animal production or meat quality. As such, reducing t10-18:1 has not been of immediate concern to ruminant meat producers, as there have been no economic consequences for its enrichment; nevertheless at high levels, it can compromise the nutritional quality of beef and lamb. In anticipation that regulations regarding TFA may focus more on t10-18:1 in beef and lamb, the present review will cover its production, analysis, biological effects, strategies for manipulation, and regulatory policy.     

混凝土分层缺陷的超声检测方法研究

为解决混凝土结构中分层缺陷的在线非接触检测难题,论文提出了利用空气耦合(简称:空耦)超声导波定量检测混凝土结构中分层缺陷的新方法。首先研究了空耦超声导波在混凝土结构中的传播特性,理论分析和实验表明,利用空耦超声波以入射角8.7°入射厚度为50 mm的混凝土板时,可以激发以A0模态为主的导波。然后构建了空耦超声导波扫查实验系统,在混凝土结构单侧利用一对倾斜8.7°的空耦探头激励和接收导波信号,通过分析发现A0模态对分层缺陷敏感,且其幅度与扫查路径中的分层缺陷尺寸存在单调变化关系;在此基础上,对检测区域进行扫查,利用不同位置处的导波信号幅度实现分层缺陷的二维成像。实验结果表明,该方法不仅可以避免耦合剂对检测结果的影响,同时可实现对服役状态下混凝土结构中分层位置及尺寸的定量检测。     

基于空气耦合超声的激光焊缝质量评估

随着激光焊接技术在汽车及轨道交通上的广泛应用,对激光焊缝的无损检测技术要求越来越高. 针对3 mm以下的两层金属薄板激光焊缝为对象,探讨了空气耦合超声检测技术对激光焊缝检测的可能性. 利用数值解析和试验分析两种方法,在空气中对铝板激励兰姆(Lamb)波,通过Lamb波在激光焊缝试件中的传播模拟,分析了激光焊缝的宽度以及焊缝的良否对反射率及透射率的影响,解明了Lamb波在激光焊缝试件中的传播规律. 结果表明,可以利用Lamb波A0模式对激光焊缝的质量进行评估.     

Growth Performance,Carcass Characteristics,Fatty Acid Composition,and Blood Biochemical Parameters of Lamb Fed Diet with the Addition of Lingonberry Leaves and Oak Bark

The aim of the study is to determine the effect of natural additives supplemented to the lamb diet on lamb performance, fatty acid (FA) composition of edible parts of lambs, and biochemical plasma indices. The study is carried out on 18 male lambs, allocated to three groups in a randomized complete block design. Control animals (CON) are fed a basic diet, while the experimental lambs additionally receive lingonberry leaves (VVI) or oak bark (QUE) (10 g d^?1), as a different source of tannins. Supplementing lambs with the VVI diet decreases fat content in the longissimus dorsi muscle (MLD). The VVI diet decreases monounsaturated fatty acid (MUFA) concentration (including C18:1 cis‐9) in the MLD, increases the proportion of C16:0, C16:1, C17:1, and C22:6 n‐3 in the semitendinosus muscle, as well as increases the n‐6/n‐3 ratio and thrombogenic index in the liver. The addition of QUE to lamb diets decreases C17:1 concentration and increases the content of C18:1 trans‐11 in the MLD. Tannins‐enriched diets increase low density lipoprotein concentrations in the blood plasma. The VVI diet increases the activity of alkaline phosphatase, while QUE supplementation decreases gamma‐glutamyl transferase activity in blood plasma. Modifications of FA composition in lamb tissues may suggest an indirect effect of tannins on FA ruminal biohydrogenation. Practical Applications: The use of VVI and QUE in lamb nutrition as natural resources is of a great interest to scientists. The present study shows that primarily VVI addition to lamb diets affects the quality of meat, due to higher proportion of catechin than QUE. Decreased concentration of fat, as well as increased proportion of C22:6 n‐3 and desirable fatty acids (including MUFA, polyunsaturated fatty acid, C18:0) after VVI supplementation increases health‐promoting properties of lamb meat and is related to humans. However, the presence of biologically active substances (tannins) in the examined additives makes it necessary to further research and discover their full potential in many areas.     

液体-压电晶片界面兰姆波激发的理论研究

对液体 -压电晶片结构中叉指换能器所激发的兰姆波进行了理论研究和数值分析 ,给出了兰姆波的相速度、叉指换能器激发兰姆波的机电耦合系数与压电晶片的归一化厚度、晶体切向之间的关系曲线 ,为液体密度兰姆波声传感器的研究提供了理论基础。     

固体火箭发动机装药界面胶接质量超声波检测

在钢-橡胶胶接中,胶层缺陷的存在会改变入射声波能量在胶接界面的分配。利用超声板波诱发波检测技术,对固体火箭发动机装药界面胶接质量进行检测。结果表明,采用该检测方法不仅可以直观地检测各界面的胶接质量,同时还可以检测第一层橡胶材料(如绝热层或包覆层)的厚度。     

Characterization by culture-dependent and culture-independent methods of the bacterial population of suckling-lamb packaged in different atmospheres

This study offers insight into the dynamics of bacterial populations in fresh cuts of suckling lamb under four different atmospheric conditions: air (A), and three Modified Atmosphere Packaging (MAP) environments, 15%O₂/30%CO₂/55%N₂ (C, commercial), 70%O₂/30%CO₂ (O), and 15%O₂/85%CO₂ (H) for 18 days. Microbial analyses by both conventional methods and PCR-DGGE were performed. Controversial and surprising results emerged from comparing both methods in relation to the genus Pseudomonas. Thus, conventional methods detected the presence of high numbers of Pseudomonas colonies, although PCR-DGGE only detected this genus in air-packaged samples. PCR-DGGE detected higher microbial diversity in the control samples (A) than in the modified atmospheres (C, O, H), having atmosphere H the fewest number of species. Brochothrix thermosphacta, LAB (Carnobacterium divergens and Lactobacillus sakei), and Escherichia spp. were detected in all the atmospheres throughout storage. Moreover, previously undescribed bacteria from lamb meat such as Enterobacter hormaechei, Staphylococcus equorum and Jeotgalicoccus spp. were also isolated in this study by DGGE. Additionally, qPCR analysis was used to detect and characterize strains of Escherichia coli. Virulence genes (stx₁, stx₂ and eae) were detected throughout storage in 97% of the samples. A high CO₂ atmosphere was the most effective packaging combination doubling storage time in comparison with commercial atmosphere.     

小湖羊皮光面毛革的鞣前处理

本文对产于浙江杭嘉湖地区及太湖流域的名贵皮张—小湖羊皮的鞣前处理进行了实验研究,对选皮、浸水、软化、浸酸等工序的操作工艺进行了优选,所得结果对于小湖羊皮光面毛革的生产具有指导意义。     

Quantitation of Lamb Content in Mixtures with Raw Minced Beef Using Visible, Near and Mid-Infrared Spectroscopy

Samples of beef (32), lamb (33) and 5%, 10% and 20% (w/w) lamb-in-beef mixtures (33 each) were minced and reflectance scanned in the visible, near and mid-infrared spectral regions. Partial least squares (PLS) regression models were developed to predict percentage lamb content using each spectral region alone and combinations of all three. The most accurate models combined mid-IR (800-2000 cm^-1) and near IR (1100-2498 nm) spectral data following 2^nd derivatization; standard errors of prediction of 0.91% (0–20% range in lamb content) and 4.1% (0–100% range in lamb) were obtained. This technique may be useful for screening such meat mixtures.     

激光半经典理论三阶近似适用性的研究

导出了用相对激光度表示的更为一般的气体激光器单模无量纲稳态光强的精确方程，深入了激光半经典理论三阶近似，修正了Ｍ．ＳａｒｇｅｎｔⅢ等人三阶近似理论的适用性范围，给出了用三阶分析气体激光器光强与兰姆凹陷特性的合适范围。