Molecular order versus vitrification in high-sugar blends of gelatin and kappa-carrageenan

The understanding of synthetic polymer viscoelasticity was applied to the small deformation properties of high-sugar gelatin and kappa-carrageenan mixtures. The glass transition zone in sugar/gelatin mixtures exhibited a dominant liquid-like response, which was followed by the method of reduced variables. The glass transition temperature predicted by the WLF/free volume approach coincided with the crossover of storage and loss modulus at the onset of the glassy state. The viscoelastic spectrum was resolved into a basic function of temperature and a basic function of time, thus rationalizing their effect on the vitrification of the mixture. Vitrification was only one in a plethora of viscoelastic properties. Manipulation of the composition of the mixture generated a continuous gelatin matrix or a viscous sugar phase suspending a dispersion of ice crystals. Besides the small-molecule crystallinity, vitrification can be halted by ordered macromolecular helices observed in the kappa-carrageenan/potassium system. Thus, the solid-like component of the sugar/kappa-carrageenan network remained prevalent over the predicted frequency window. The WLF equation was unable to follow the progress of viscoelastic functions, which were better described by an energetic barrier of rotation from one state to another.     

Seasonal speedup along the western flank of the Greenland Ice Sheet

It has been widely hypothesized that a warmer climate in Greenland would increase the volume of lubricating surface meltwater reaching the ice-bedrock interface, accelerating ice flow and increasing mass loss. We have assembled a data set that provides a synoptic-scale view, spanning ice-sheet to outlet-glacier flow, with which to evaluate this hypothesis. On the ice sheet, these data reveal summer speedups (50 to 100%) consistent with, but somewhat larger than, earlier observations. The relative speedup of outlet glaciers, however, is far smaller (<15%). Furthermore, the dominant seasonal influence on Jakobshavn Isbrae's flow is the calving front's annual advance and retreat. With other effects producing outlet-glacier speedups an order of magnitude larger, seasonal melt's influence on ice flow is likely confined to those regions dominated by ice-sheet flow.     

鸡痘冻干保护剂热稳定性的研究

利用筛选的鸡痘热稳定性保护剂与鸡痘病毒悬液混合后 ,制成冻干制品。研究结果表明 :制品在 3 8℃作用 10d外观无明显变化 ,作用 2 1d后制品稍有萎缩 ;作用 10和 2 1dEID50 ( 0 .2ml)分别为 10 - 6 .5和 10 - 7.5。     

Bioavailability of genistein and its glycoside genistin as measured in the portal vein of freely moving unanesthetized rats

The present study describes an in vivo bioavailability experiment for genistein and its glycoside genistin, either as pure compounds or from a soy protein isolate extract, using freely moving unanesthetized rats with a cannulation in the portal vein. The results show that genistein is readily bioavailable, being observed in portal vein plasma at the first point of detection at 15 min after dosing. The AUC(0-24h) values for total genistein and its conjugates were 54, 24, and 13 microM h for genistein, genistin, and an enriched protein soy extract, respectively. These results indicate that the bioavailability of genistein is higher for the aglycon than for its glycoside. Genistin is partly absorbed in its glycosidic form. It is concluded that bioavailability studies based on portal vein plasma levels contribute to insight into the role of the intestine and liver in deglycosylation and uptake characteristics of glycosylated flavonoids.     

Magnetism from the atom to the bulk in iron, cobalt, and nickel clusters

Molecular beam deflection measurements of small iron, cobalt, and nickel clusters show how magnetism develops as the cluster size is increased from several tens to several hundreds of atoms for temperatures between 80 and 1000 K. Ferromagnetism occurs even for the smallest sizes: for clusters with fewer than about 30 atoms the magnetic moments are atomlike; as the size is increased up to 700 atoms, the magnetic moments approach the bulk limit, with oscillations probably caused by surface-induced spin-density waves. The trends are explained in a magnetic shell model. A crystallographic phase transition from high moment to low moment in iron clusters has also been identified.     

苯巴比妥治疗马3—甲基吲哚中毒的疗效观察

为了研究马3—甲基吲哚(3MI)中毒时赖以双功能氧化酶反应的细胞色素P—450的作用,试验马每公斤体重投服100毫克3MI,诱导细胞色素P-450,而后在24、36、48、60、72小时投服20毫克苯巴比妥,对照组不投服该药。血浆中3MI最大浓度降低,投服苯巴比妥的清除速度较快。试验组和对照组在12、36小时后,血浆中3MI浓度仍可测得。苯巴比妥处理诱导了它在血管外模型从Ⅰ区间向Ⅱ区间转移的分布相。投服3MI 72小时后,所有马都发生了细支气管炎,但是用苯巴比妥治疗的马更为严重,这显现出一种分布相,增加了整体的清除。     

林地覆盖物对干旱地区造林树种的影响

前言巴基斯坦有生产效能的林仅占总土地面积的1.3％,因此,木材的供求之间有很大的差距,薪炭柴更是极缺。天然气、燃油和煤只能解决所需能源的13％,牲畜粪和农作物秸秆也用作燃料,解决需能源的87％。大约有90％的农村人口和50％的城市人口依靠这些非商业性的燃料。家庭做饭和取暖所需木柴的总消耗量为16000000立方米,而国家森林只能提供250000立方米。昔日是薪炭柴源的荒地渐渐地变成光秃秃的裸地,在这些地区进行人工造林是建立预备林的唯一希望所在。世界各地都在试验研究干旱地区造林的各种技术,其中之一