The use of optically stimulated luminescence from AL2O3:C in the dosimetry of high-energy heavy charged particle fields

This paper presents two different approaches of quantifying the optically stimulated luminescence (OSL) response of Al(2)O(3):C to high-energy heavy charged particles (HCPs). The OSL efficiency of Al(2)O(3):C exposed to different HCPs is defined as the sensitivity of the material to HCPs normalised by the sensitivity to gamma. In this paper, we investigate the possibility of introducing a 'mean efficiency' eta(mean), which when used in conjunction with the total gamma dose D(gamma) measured for a mixed radiation exposure allows for the determination of the absorbed dose without the need to determine the individual contributions of different types of radiation to the OSL signal. We tested the hypothesis that information regarding the 'mean efficiency' eta(mean) is contained in the shape of the OSL decay curve, using several approaches in the analysis of the OSL data. This analysis was applied to various mixed field irradiations performed at the HIMAC facility, Chiba, Japan. The results of this analysis are discussed.     

Bifidobacterium carbohydrases-their role in breakdown and synthesis of (potential) prebiotics

There is an increasing interest to positively influence the human intestinal microbiota through the diet by the use of prebiotics and/or probiotics. It is anticipated that this will balance the microbial composition in the gastrointestinal tract in favor of health promoting genera such as Bifidobacterium and Lactobacillus. Carbohydrates like non-digestible oligosaccharides are potential prebiotics. To understand how these bacteria can grow on these carbon sources, knowledge of the carbohydrate-modifying enzymes is needed. Little is known about the carbohydrate-modifying enzymes of bifidobacteria. The genome sequence of Bifidobacterium adolescentis and Bifidobacterium longum biotype longum has been completed and it was observed that for B. longum biotype longum more than 8% of the annotated genes were involved in carbohydrate metabolism. In addition more sequence data of individual carbohydrases from other Bifidobacterium spp. became available. Besides the degradation of (potential) prebiotics by bifidobacterial glycoside hydrolases, we will focus in this review on the possibilities to produce new classes of non-digestible oligosaccharides by showing the presence and (transglycosylation) activity of the most important carbohydrate modifying enzymes in bifidobacteria. Approaches to use and improve carbohydrate-modifying enzymes in prebiotic design will be discussed.     

Fate of Salmonella Tennessee in peanut butter at 4 and 22 degrees C

ABSTRACT:  This study was undertaken to determine survival characteristics of inocula of a 3-strain mixture of Salmonella Tennessee in 5 commercial brands of peanut butter (A, B, C, D, and E). Inoculated peanut butter was stored at 4 (refrigerator temperature) and 22 °C (room temperature) for up to 14 d. After 1, 3, 5, 7, and 14 d, surviving cells, including injured cells, were enumerated on appropriate selective agar, including use of the agar overlay method. Populations in samples inoculated with 10^6–7 CFU/g and stored for 14 d at 4 and 22 °C decreased by 0.15 to 0.65 and 0.34 to 1.29 log CFU/g, respectively, depending on the formulation. Peanut butter A showed a significantly lower number of S . Tennessee cells when stored at 22 °C for 14 d, compared to 4 °C ( P < 0.05). However, there was no significant difference between the levels of S. Tennessee at 4 and 22 °C in products B, C, D, and E ( P > 0.05).     

Decreasing concentrations of PCDD/Fs in pork based on Korean monitoring in years 2002 and 2005

The congener-specific profiles of PCDD/Fs in domestic and imported pork monitored in South Korea in years 2002 and 2005 were compared. Total concentrations of PCDD/Fs decreased from 2002 to 2005, but displayed a similar pattern of congeners. In neither 2002 nor 2005 were either 2,3,7,8-TCDD or 2,3,7,8-TCDF detected. The mean concentrations of PCDD/Fs in domestic and imported pork were 8.29 pg g(-1) fat from 106 samples in 2002 and 4.03 pg g(-1) fat from 90 samples in 2005. However, the contribution of PCDDs increased about four times with respect to toxic equivalent (TEQ) level and about 1.5 times in terms of concentration in the monitoring results from 2005 compared with 2002, and the PCDF contribution decreased substantially. This suggests that the main source of dioxins in pork probably changed to a larger portion coming from animal feeds than environmental sources of exposure. The estimated human intakes of PCDD/Fs originating from pork in the South Korean diet were calculated as 0.029 and 0.019 pg TEQkg(-1) body weight day(-1) for the upper bound exposure in 2002 and 2005, respectively. The values represent low intakes when compared with the both Korean tolerable daily intake (TDI) (4 pg TEQkg(-1) body weight day(-1)) and World Health Organization TDI (1-4 pg TEQkg(-1) body weight day(-1)).     

淀粉类凝胶三维打印研究进展

食品三维打印技术是食品加工业革命性的创新发展, 能够在未来解决我国食品加工业和食品产业面临的营养个人订制性以及生产适合老人和婴幼儿的易咀嚼食品诸多问题。淀粉是食品中最常见的组分, 其在高温发生糊化并且与其他组分交联形成的凝胶体系是很好的食品三维打印材料。本文先是阐释了挤压式食品三维打印技术的工作原理, 以及淀粉的结构及物理化学性质, 揭示了淀粉的物理化学性质与淀粉类材料三维打印形状稳定性之间的联系, 从而进一步介绍了材料特性、三维打印挤出行为及后处理方法对淀粉三维打印产品形状稳定性的影响以及兼具易咀嚼特性和个性化营养特性的三维打印产品的相关研究。     

PLA协同纳米CaCO3增韧PP的研究

通过熔融共混制得聚丙烯/聚乳酸/纳米碳酸钙（PP/PLA/CaCO3）复合材料,考察了PLA和纳米CaCO3对复合材料力学性能、热性能、流变性能与结晶形态的影响及其作用机理。结果表明,复合材料中形成连续空间网络结构的PLA有助于改善PP的性能,PLA含量为20 %（质量分数,下同）时复合材料综合力学性能最佳;与纯PP相比,加入PLA后的复合材料拉伸强度和冲击强度分别提高5.1 %和54.4 %,断裂伸长率降低62.5 %;纳米CaCO3通过“滚珠增韧”和“异相成核”作用明显改善复合材料力学性能,纳米CaCO3含量15 %时产生的晶粒细化作用效果最为显著,复合材料综合力学性能达到最佳,拉伸强度、断裂伸长率和冲击强度分别比未添加CaCO3时提升了15.2 %、2.7 %和5.6 %。     

旱地“油稻三熟”新型绿色高产高效生产模式

当前棉花、玉米市场疲软,价格持续下滑,农民面临大量耕地闲置,为适应农业供给侧发展要求,在赣北丘陵棉田开展节水抗旱稻+再生+油菜高产高效模式攻关示范。赣北丘陵属于少雨地区,年降雨量1 300～1 600 mm,春季雨水充沛,夏秋干旱为主,按此模式生产,将大大减少耕地闲置,为农业增产、农民增收带来效益。     

锅炉压力容器DIWA353钢板韧脆转变温度的测定

锅炉与压力容器用钢板的韧性会随着温度的下降而降低,并且在达到某一温度时会发生韧脆转变现象,导致产品的性能不符合技术要求.采用V型缺口试样,通过系列温度的冲击试验,以冲击吸收功、脆性断面率的变化对锅炉压力容器用DIWA353钢板的韧脆转变温度进行了测定.     

Processes controlling the thermal regime of saltmarsh channel beds

Spatially and temporally continuous temperature measurements were collected over 32 h using a fiber-optic distributed temperature sensing (DTS) system deployed along 330 m of two intertidal saltmarsh channel beds in northern California. Measured temperature gradients imparted ecosystem-scale structure to the saltmarsh tidal channel thermal regime, which was punctuated by potential warm and cold refugia. Anomalous bed temperatures of 2-4 degrees C occurred throughout the 1.3 tidal cycles at some locations. Discrete locations of consistently warm temperatures characterized sustained seepage of recently infiltrated tidal waters. Low-variance temperature anomalies were typically collocated with hidden microtopographic tributaries that facilitated mixing of warm surface waters and cold groundwater. Bed temperature gradients (approximately 2 degrees C/100 m, average) decreased from high temperatures similar to bay water at the channel mouths to low inland temperatures comparable to groundwater. The trends were maintained by cold groundwater discharge throughout the channels, which affected bed temperatures in proportion to channel reach exposure time; the opposing effect, conductive bed-warming by tidal waters, was proportional to flood duration. DTS is a promising tool for identifying spatial and temporal temperature patterns of hydroecological importance amidst complex natural systems.     

Development of microbial genome-probing microarrays using digital multiple displacement amplification of uncultivated microbial single cells

A crucial problem in the use of previously developed genome-probing microarrays (GPM) has been the inability to use uncultivated bacterial genomes to take advantage of the high sensitivity and specificity of GPM in microbial detection and monitoring. We show here a method, digital multiple displacement amplification (MDA), to amplify and analyze various genomes obtained from single uncultivated bacterial cells. We used 15 genomes from key microbes involved in dichloromethane (DCM)-dechlorinating enrichment as microarray probes to uncover the bacterial population dynamics of samples without PCR amplification. Genomic DNA amplified from single cells originating from uncultured bacteria with 80.3-99.4% similarity to 16S rRNA genes of cultivated bacteria. The digital MDA-GPM method successfully monitored the dynamics of DCM-dechlorinating communities from different phases of enrichment status. Without a priori knowledge of microbial diversity, the digital MDA-GPM method could be designed to monitor most microbial populations in a given environmental sample.