ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Impedance spectroscopy
  • Lipids
  • Springer  (5)
  • American Chemical Society
  • International Union of Crystallography (IUCr)
  • 2020-2023
  • 2020-2022
  • 1995-1999  (5)
  • 1945-1949
  • 1999  (5)
Collection
Keywords
Publisher
  • Springer  (5)
  • American Chemical Society
  • International Union of Crystallography (IUCr)
Years
  • 2020-2023
  • 2020-2022
  • 1995-1999  (5)
  • 1945-1949
Year
  • 1
    Electronic Resource
    Electronic Resource
    Semiconducting properties of polypyrrole films in aqueous solution (1999)
    Springer
    Journal of solid state electrochemistry 3 (1999), S. 406-411 
    Details
    ISSN: 1433-0768
    Keywords: Key words Polypyrrole ; Anion influence ; Film thickness ; Photocurrent ; Impedance spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The influence of the nature of the anions on the conductivity of polypyrrole films in aqueous solution was investigated by photocurrent spectroscopy combined with electrochemical impedance spectroscopy in dependence on the potential. As demonstrated, the conductivity of polypyrrole films at negative potentials can vary from a semiconducting to an ionic conducting state, depending on the size of the charge-compensating counter-anion incorporated during the electropolymerization. The reduced polypyrrole shows semiconducting properties when small anions are inserted, releasing the polymer matrix during the reduction process. The polymer can than be considered as a two-layer system, consisting of a semiconducting layer and a porous layer. Measurements at different thickness of polypyrrole films have shown that the position of the semiconducting layer is in the electrode/polymer interface. The ohmic resistance of the semiconducting layer is in the range 1–5 kΩ, the capacitance approaches a value of 100–500 nF and the flatband potential is −0.62 VSCE. If large anions are incorporated, cation insertion takes place during reduction, the electrolyte content in the polymer then is relatively high and the polymer's behaviour is similar to that of an ionic conductor. The results are presented and discussed together with the example of methylsulfonate as a relatively small anion and polystyrenesulfonate as a large anion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s100080050174
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The allometry of energy reserve depletion: test of a mechanism for size-dependent winter mortality (1999)
    Springer
    Oecologia 119 (1999), S. 474-483 
    Details
    ISSN: 1432-1939
    Keywords: Key words Atherinidae ; Lipids ; Metabolism ; Selection ; Starvation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We experimentally tested the hypothesis that energy reserve depletion varies inversely with size in the fish Menidia menidia, an estuarine fish known to exhibit size-dependent winter mortality. Individuals in two size groups were starved at two winter temperatures (4°and 8°C) and sacrificed at a range of time intervals (up to 127 days). Lipid levels and lean tissue were analyzed to estimate somatic energy storage. As predicted, energy depletion was greater at high temperatures, and proportionally greater in small than in large fish. After 60 days of starvation at 4°C, small fish retained an average of 67% of their original energy reserves (vs 53% at 8°C), while large fish retained an average of 80% (vs 66% at 8°C). At 4°C, fish that were fed depleted their energy reserves as rapidly as unfed fish, but at 8°C, fish that were fed maintained reserves at higher levels than unfed fish. A high proportion of unfed fish (56% at 4°C, 27% at 8°C) died before they were to be sacrificed. Survival probability did not vary with size, nor was it influenced by the amount of energy reserves. The rate of energy depletion (equivalent to routine metabolic rate) decreased gradually over time, particularly in small fish. Routine metabolism did not conform to a single scaling relationship. Within each temperature-size group, the routine rate declined more rapidly than metabolically active mass (lean mass). At 8°C, the difference between size groups in energy depletion rate conformed closely to the expected allometry exponent of 0.8. In contrast, at 4°C, the estimated allometry exponent increased over the experiment (−0.19 to 2.5). We conclude that strategies to minimize energy loss may often modify bioenergetic scaling relationships.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050810
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    In vitro alteration of macrophage phenotype and function by serum lipids (1999)
    Springer
    Cell & tissue research 296 (1999), S. 331-337 
    Details
    ISSN: 1432-0878
    Keywords: Key words Cytokine ; ELISA ; FACScan ; Lipids ; Macrophage ; Monocyte ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Diabetes (type I and type II) affects approximately 13 million people in the United States. Delayed and incomplete healing of wounds can be a major problem for diabetic patients. Macrophages are an important cell in the complex process of wound repair representing the major source of cytokines throughout the wound-healing process. Cytokines mediate many of the cellular responses critical to timely wound repair. It has been suggested that diabetes impairs wound healing through disruption of local cytokine production. Our previous in vivo studies in rats demonstrated that diabetes-induced and diet-induced hyperlipidemia cause changes in macrophage phenotype and function (Iacopino 1995; Doxey et al. 1998), suggesting that alterations in macrophage cytokine profiles represent the cellular/molecular mechanism responsible for delayed wound healing. The purpose of this study was to investigate how monocyte maturation/differentiation and cytokine production were altered by serum lipids in an in vitro system using human cells. Commercially prepared purified human monocytes were cultured and exposed to serum lipids. Phenotypic analysis of differentiated macrophages was then performed by flow cytometry and fluorescent microscopy using surface antigens specific for various macrophage subsets. Selected cytokines in conditioned medium were assayed using commercial human enzyme-linked immunosorbent assay (ELISA) kits. We demonstrate that serum lipids cause an increase in monocytic differentiation leading to an inflammatory macrophage phenotype rather than a reparative/proliferative phenotype. We also show that serum lipids cause a generalized decrease in macrophage cytokine production using interleukin-1 beta (IL-1β), tumor necrosis factor alpha (TNF-α), platelet-derived growth factor (PDGF), and transforming growth factor beta 1 (TGF-β1) as marker cytokines. Our present in vitro results using human cells confirm our previous in vivo studies in the rat and support the hypothesis that diabetes-induced hyperlipidemia alters the monocyte differentiation process resulting in changes of macrophage subsets and cytokine release at the wound site, ultimately impairing the wound-healing process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051293
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Influence of palm oil ( Elaesis guineensis) on health (1999)
    Springer
    Plant foods for human nutrition 53 (1999), S. 209-222 
    Details
    ISSN: 1573-9104
    Keywords: Fatty acids ; Health hazards ; Lipids ; Oxidation ; Palm oil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In recent times there has been a growing research interest in palm oil, one of the major edible plant oils in the tropical countries, because of the link between dietary fats and coronary heart disease. Obtained from a tropical plant, Elaesis guineensis, it has a polyunsaturated fatty acid/saturated fatty acid ratio close to unity and a high amount of antioxidant vitamin A precursors and vitamin E. Palm oil is consumed in the fresh state and/or at various levels of oxidation. Feeding experiments in various animal species and humans have highlighted the beneficial role of fresh palm oil to health. These benefits include reduction in the risk of arterial thrombosis and atherosclerosis, inhibition of cholesterol biosynthesis and platelet aggregation, and reduction in blood pressure. However, a considerable amount of the commonly used palm oil is in the oxidized state which possesses potential dangers to the physiological and biochemical functions of the body. Oxidation is as a result of processing the oil for various culinary purposes. Studies have revealed that relative to fresh palm oil, oxidized palm oil induces an adverse plasma lipid profile, free fatty acids, phospholipids and cerebrosides. Additionally, oxidized palm oil induces reproductive toxicity and organotoxicity particularly of the kidneys, lungs, liver and heart. Available evidence suggests that at least part of the oxidized oil impact on health reflects generation of toxicants due to oxidation. The reduction of the dietary level of oxidized oil and/or the level of oxidation may reduce the health risk associated with consumption of oxidized fats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008089715153
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    The effects of nitrogen fertilisation and elevated CO2 on the lipid biosynthesis and carbon isotopic discrimination in birch seedlings (Betula pendula) (1999)
    Springer
    Plant and soil 216 (1999), S. 35-45 
    Details
    ISSN: 1573-5036
    Keywords: Betula pendula ; Nitrogen fertilisation ; CO2 concentration ; Carbon isotopic fractionation ; Lipids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of nitrogen (N) fertilisation and elevated [CO2] on lipid biosynthesis and carbon isotope discrimination in birch (Betula pendula Roth.) transplants were evaluated using seedlings grown with and without N fertiliser, and under two concentrations of atmospheric CO2 (ambient and ambient+250 μmol mol-1) in solar dome systems. N fertilisation decreased n-fatty acid chain length (18:0/16:0) and the ratios of α-linolenate (18:2)/linoleate (18:1), whereas elevated [CO2] showed little effect on n-fatty acid chain length, but decreased the unsaturation (18:2+18:1)/18:0. Both N fertilisation and elevated [CO2] increased the quantity of leaf wax n-alkanes, whilst reducing that of n-alkanols by 20–50%, but had no simple response in fatty acid concentrations. 13C enrichment by 1–2.5‰ under N fertilisation was observed, and can be attributed to both reduced leaf conductance and increased photosynthetic consumption of CO2. Individual n-alkyl lipids of different chain length show consistent pattern of δ13C values within each homologue, but are in general 5–8‰ more depleted in 13C than the bulk tissues. Niether nitrogen fertilisation and elevated CO2 influenced the relationship between carbon isotope discrimination of the bulk tissue and the individual lipids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1004771431093
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...