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171.
随着仪器性能的不断提高,飞行时间二次离子质谱(TOF-SIMS)在材料表面化学分析中起着越来越重要的作用。TOF-SIMS的主要测试功能包括表面质谱、化学成像及深度剖析,本工作对TOF-SIMS的化学成像及深度剖析2种功能在生物材料和生命科学中的应用做了简单综述,重点介绍了TOF-SIMS成像技术在生物芯片制备工艺中的应用和TOF-SIMS成像和深度剖析技术对生物分子在细胞和生物体组织上空间分布的表征方法;另外,对生物样品的低温制备方法,样品表面添加基质以增强信号强度的实验手段,使用团簇一次离子源提高分子二次离子产额和利用对样品损伤小的C60离子源为轰击源做深度剖析等实验做了简单的介绍;最后,对TOF-SIMS在生物生命材料领域的应用做了展望。 相似文献
172.
173.
The accurate prediction of cost profiles of future job tasks on the nodes of clusters or grids helps users to select the cost performance profile that best suits their budgets. The current software designed to deploy job tasks uses forecasts of the target computers' future load profiles. Once the job task's future load profile is known, converting it to its cost profile needs further analysis as the cost depends on other factors such as its delays and variable background loads. This paper introduces a new charging mechanism for charging future job tasks, called the Cost Profiling Model. The model has been implemented in a Software Framework and evaluated for its prediction accuracy. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
174.
Dr. Anna Knapinska Prof. Gregg B. Fields 《Chembiochem : a European journal of chemical biology》2012,13(14):2002-2020
The matrix metalloproteinase (MMP) family has long been associated with normal physiological processes such as embryonic implantation, tissue remodeling, organ development, and wound healing, as well as multiple aspects of cancer initiation and progression, osteoarthritis, inflammatory and vascular diseases, and neurodegenerative diseases. The development of chemically designed MMP probes has advanced our understanding of the roles of MMPs in disease in addition to shedding considerable light on the mechanisms of MMP action. The first generation of protease‐activated agents has demonstrated proof of principle as well as providing impetus for in vivo applications. One common problem has been a lack of agent stability at nontargeted tissues and organs due to activation by multiple proteases. The present review considers how chemical biology has impacted the progress made in understanding the roles of MMPs in disease and the basic mechanisms of MMP action. 相似文献
175.
M. Morzel E. M. Sheehan C. M. Delahunty E. K. Arendt 《International Journal of Food Science & Technology》1999,34(2):115-123
Summary In order to characterise a novel fermented salmon product, sensory evaluation by free-choice profiling was undertaken on three different types of salmon products (smoked salmon, gravlax and fermented salmon). Assessors could easily discriminate among all three types of products and common attributes were isolated from the set of individual assessments. Discrimination was made according to the appearance, odour and flavour attributes, while no clear consensus on texture was observable. The first discrimination factor between all products was the presence/absence of a smoky character. The novel fermented salmon was discriminated from gravlax as it appeared to have a distinct sour/ acidic odour and flavour. 相似文献
176.
Distribution and carbon isotope composition of lipid biomarkers in Lake Erhai and Lake Gahai sediments on the Tibetan Plateau 总被引:1,自引:0,他引:1
Lipid biomarkers and carbon isotopes of n-alkanes, n-fatty acids, and n-alkan-2-ones were used to determine organic carbon sources to surface sediments in lakes Erhai and Gahai on the Tibetan Plateau. All sediment samples contained n-fatty acids with lower concentrations of n-alkanes and n-alkan-2-ones. Long chain n-alkanes in lake sediments were characteristic of a source mixture of epicuticular waxes of higher plants and submerged littoral zone plants while n-fatty acids sources were bacteria and floating and/or submergent macrophytes; the n-alkan-2-ones had a possible source in epicuticular waxes of higher plants and/or grass from catchment which entered the lake and were reworked by the microorganisms. Sediment samples examined from Lake Erhai had heavier δ13C values of bulk organic carbon and specific carbon compounds than samples from Lake Gahai and meadow soil. This heavier isotopic composition can be best interpreted by the enhanced productivity occurring in Lake Erhai due to its lower salinity and possibly to limited CO2 concentrations; for the latter, this may have enriched 13C in the dissolved inorganic carbon pool of the lake water. 相似文献
177.
Antioxidant Activity of Added Phenolic Compounds in Freeze-Dried Microencapsulated Sunflower Oil 总被引:1,自引:0,他引:1
Joaquín Velasco Francisca Holgado Carmen Dobarganes Gloria Márquez-Ruiz 《Journal of the American Oil Chemists' Society》2009,86(5):445-452
This study was aimed at evaluating the effectiveness of phenolic antioxidants with a similar structure but having a different
polarity in dried microencapsulated sunflower oil. The antioxidants tested were, on one hand, α-tocopherol and its water soluble
analogue, Trolox, and on the other, gallic acid and its ester derivatives, propyl gallate and dodecyl gallate. At a moderate
temperature (40 °C), the samples were oxidized under accelerated conditions by using Cu(II) as an oxidation catalyst. The
progress of oxidation was followed up over time in the free and encapsulated oil fractions. The peroxide value, the total
content of polymers and, when appropriate, the content of α-tocopherol were determined. Quantitative analysis of the total
fraction of the non-volatile oxidation products and their distribution in oligomers, dimers and monomers was applied to samples
to obtain a complete evaluation of oxidation. Finally, as a complementary measure, the antioxidants were also assessed by
direct application of the Rancimat test at 100 °C on the dried microencapsulated oil samples. Results showed that the antioxidants
of lower polarity in each series, i.e. tocopherol and dodecyl gallate, were to a great extent the most protective antioxidants.
The results obtained by the Rancimat test were consistent with those found during oxidation at moderate temperature. Furthermore,
the addition of Cu(II) reduced proportionally the oxidative stability index of the dried microencapsulated samples. 相似文献
178.
Sensory odour profiling and lipid oxidation status of fish oil and microencapsulated fish oil 总被引:1,自引:0,他引:1
The aim of the present study was to evaluate the suitability of defined odour attributes for the sensory evaluation of bulk fish oil and reconstituted microencapsulated fish oil as well as the active modification of the sensory profile during storage. Common attributes previously described for bulk fish oil (fishy, metallic, pungent, green notes) proved to be suitable for the sensory evaluation of reconstituted microencapsulated fish oil. Additional attributes were identified in dependence on the bulk fish oil processing (sweet/biscuit-like) and of constituents of the microcapsule carrier matrix (seasoning-like). Reconstituted sodium caseinate-based microcapsules exhibited a lower fishy odour during storage than did n-octenylsuccinate-derivatised starch-based microcapsules, probably due to the oxidative status. Flavour binding of caseinate may be of minor importance in reconstituted microencapsulated fish oil. Improvement of the sensory profile was achieved by the addition of an odour-masking compound (β-cyclodextrin) or flavouring (vanillin and apple flavour). 相似文献
179.
Quality of Crude Oil Extracted from Aging Walleye Pollock (<Emphasis Type="Italic">Theragra chalcogramma</Emphasis>) Byproducts 总被引:1,自引:1,他引:0
The quality of crude oil was examined as a function of the temperature and delay time between collecting and processing the
fish byproducts from a commercial cannery into crude oil. Extracts from pollock byproducts stored at 6 and 15 °C for up to
4 and 10 days was examined. Longer storage of byproducts resulted in higher free fatty acid (FFA) and an increase in retinol
levels in the extracted crude oils. Primary and secondary oxidation assays consisting of peroxide value and thiobarbituric
acid-reactive substances increased initially with storage time on day 1 followed by an unexpected decrease with storage time.
Higher storage temperature resulted in greater FFA and retinol levels, but lower oxidation products in the crude oils. The
tocopherol levels decreased with storage time of the byproducts with no differences between the storage temperatures. Eicosapentaenoic
acid, docosahexaenoic acid and polyunsaturated fatty acids percentage remained similar in the extracted oils with the respective
storage time or temperature treatments. 相似文献
180.
Enzymatic oxidative activity in sardine (Sardina pilchardus) and herring (Clupea harengus) during chilling and correlation with quality 总被引:1,自引:0,他引:1
Enzymatic oxidative activity of two fatty fish species, sardine (Sardina pilchardus) and herring (Clupea harengus), was studied during chilled storage. Lipoxygenase enzyme activity was isolated and tested by measuring the hydroperoxides
produced after induced oxidation of arachidonic and docosahexaenoic fatty acids. The most abundant degradation products of
the hydroperoxides formed were 12- and 16-hydroxy acids which were detected by HPLC. Lipoxygenases were concentrated in the
skin tissue of fish, and were active for up to 48 h of chilled storage. The pro-oxidative activity due to haem proteins continued
for longer than that due to lipoxygenase. Trends of fluorescent formation resulting from interaction between oxidation products
and biological amino constituents were compared with the pro-oxidative activities to establish correlations with quality loss
during chilling.
Received: 29 December 1998 / Revised version: 14 March 1999 相似文献