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  • Impedance spectroscopy
  • Lipids
  • Springer  (21)
  • American Chemical Society  (2)
  • International Union of Crystallography (IUCr)
  • 2020-2023  (2)
  • 2020-2022
  • 1995-1999  (21)
  • 1945-1949
  • 1
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    Production of two highly abundant 2-methyl-branched fatty acids by blooms of the globally significant marine cyanobacteria Trichodesmium erythraeum (2021)
    American Chemical Society
    Details
    Publication Date: 2022-05-27
    Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Gosselin, K. M., Nelson, R. K., Spivak, A. C., Sylva, S. P., Van Mooy, B. A. S., Aeppli, C., Sharpless, C. M., O’Neil, G. W., Arrington, E. C., Reddy, C. M., & Valentine, D. L. Production of two highly abundant 2-methyl-branched fatty acids by blooms of the globally significant marine cyanobacteria Trichodesmium erythraeum. ACS Omega, 6(35), (2021): 22803–22810, https://doi.org/10.1021/acsomega.1c03196.
    Description: The bloom-forming cyanobacteria Trichodesmium contribute up to 30% to the total fixed nitrogen in the global oceans and thereby drive substantial productivity. On an expedition in the Gulf of Mexico, we observed and sampled surface slicks, some of which included dense blooms of Trichodesmium erythraeum. These bloom samples contained abundant and atypical free fatty acids, identified here as 2-methyldecanoic acid and 2-methyldodecanoic acid. The high abundance and unusual branching pattern of these compounds suggest that they may play a specific role in this globally important organism.
    Description: This work was funded with grants from the National Science Foundation grants OCE-1333148, OCE-1333162, and OCE-1756254 and the Woods Hole Oceanographic Institution (IR&D). GCxGC analysis made possible by WHOI’s Investment in Science Fund.
    Keywords: Lipids ; Alkyls ; Bacteria ; Genetics ; Chromatography
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 2
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    Flow-through quantification of microplastics using impedance spectroscopy (2021)
    American Chemical Society
    Details
    Publication Date: 2022-10-21
    Description: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Colson, B. C., & Michel, A. P. M. Flow-through quantification of microplastics using impedance spectroscopy. ACS Sensors, 6(1), (2021): 238–244, doi:10.1021/acssensors.0c02223.
    Description: Understanding the sources, impacts, and fate of microplastics in the environment is critical for assessing the potential risks of these anthropogenic particles. However, our ability to quantify and identify microplastics in aquatic ecosystems is limited by the lack of rapid techniques that do not require visual sorting or preprocessing. Here, we demonstrate the use of impedance spectroscopy for high-throughput flow-through microplastic quantification, with the goal of rapid measurement of microplastic concentration and size. Impedance spectroscopy characterizes the electrical properties of individual particles directly in the flow of water, allowing for simultaneous sizing and material identification. To demonstrate the technique, spike and recovery experiments were conducted in tap water with 212–1000 μm polyethylene beads in six size ranges and a variety of similarly sized biological materials. Microplastics were reliably detected, sized, and differentiated from biological materials via their electrical properties at an average flow rate of 103 ± 8 mL/min. The recovery rate was ≥90% for microplastics in the 300–1000 μm size range, and the false positive rate for the misidentification of the biological material as plastic was 1%. Impedance spectroscopy allowed for the identification of microplastics directly in water without visual sorting or filtration, demonstrating its use for flow-through sensing.
    Description: The authors thank the Richard Saltonstall Charitable Foundation and the National Academies Keck Futures Initiative (NAKFI DBS13) for their funding support.
    Keywords: Microplastics ; Plastics ; Impedance spectroscopy ; Dielectric properties ; Instrumentation ; Particle detection ; Flow-through ; Environmental sensing
    Repository Name: Woods Hole Open Access Server
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  • 3
    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
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  • 4
    Electronic Resource
    Electronic Resource
    Fatty acids, starch and biomass of Scots pine needles and roots in open-air ozone exposure (1995)
    Springer
    Trees 10 (1995), S. 74-82 
    Details
    ISSN: 1432-2285
    Keywords: Ozone ; Pinus sylvestris (L.) ; Lipids ; Starch ; Biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Scots pine (Pinus sylvestris L.) seedlings were fumigated with 1.2–1.5 x ambient ozone (cumulative exposure) over 2 seasons in an open-air experiment. Starch and fatty acid concentrations were analyzed in needle and root tissue in the summer, autumn and early winter. Seedling growth was determined by measuring the height of the stem and the total shoot and root biomass. Significant decreases in growth were found in exposed seedlings, even though visible symptoms were lacking. Almost significant reductions in needle and root starch concentrations were found. In the ozone treated foliage, significant increases in myristic acid (14∶0) were detected, but the major fatty acids remained unchanged. Fatty acid ratios showed that the degree of unsaturation decreased in treated needles in the summer. In the roots of ozone treated seedlings, changes in fatty acids were different from those in the foliage. Decreases of the main root fatty acids (16∶0, 18∶0, 18∶1, 18:2, 18∶3) were detected in the summer. These results show that Scots pine is susceptible to enhanced levels of ozone. If the tropospheric ozone levels continue to increase it may have deleterious effects on Scots pine forests in Finland.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192186
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  • 5
    Electronic Resource
    Electronic Resource
    Carbohydrate and lipid components of hyphae and conidia of human pathogenFonsecaea pedrosoi (1995)
    Springer
    Mycopathologia 132 (1995), S. 71-77 
    Details
    ISSN: 1573-0832
    Keywords: Fonsecaea pedrosoi ; Morphogenesis ; Carbohydrates ; Lipids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The carbohydrate and lipid components of mycelium and conidia ofFonsecaea pedrosoi (Brumpt) were analysed by paper, thin-layer and gas-chromatography, mass spectrometry and ultraviolet spectroscopy. Glucose, mannose, galactofuranose, rhamnose and glucosamine were polysaccharide components identified inF. pedrosoi. Significant changes in the carbohydrate pattern occurred during the conversion of mycelium into conidia. Rhamnose was predominant in conidia whereas galactose was prominent in mycelium. Palmitic, stearic, oleic, linoleic, and arachidonic acids were the fatty acids identified in the total lipid fraction. Palmitic and oleic acids were major fatty acids. Marked alterations in the fatty acid constituents were observed between the cell types ofF. pedrosoi. Arachidonic acid was detected only in conidia and linoleic acid was preferentially identified in mycelium. Differences in the sterol composition was also associated with morphogenesis inF. pedrosoi. Two main sterols, ergosterol and another less polar sterol, not fully characterized, were found in mycelium whereas in conidia only the latter sterol was present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01103778
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of fasting and thermal acclimation on metabolism of juvenile axolotls (Ambystoma mexicanum) (1998)
    Springer
    Experimental biology online 3 (1998), S. 1-11 
    Details
    ISSN: 1430-3418
    Keywords: Ambystoma mexicanum ; Axolotls ; Citrate synthase ; Cytochrome oxidase ; Lactic dehydrogenase ; Lipids ; Metabolic rate ; Nutrition ; Thermal acclimation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Juvenile axolotls were acclimated to 15○C or 25○C and either fed or fasted at both temperatures, to study the interaction of thermal acclimation and nutritional state on metabolism. Fasting but not thermal acclimation significantly increased oxygen consumption at 15○C. Fasting also increased the specific activities of two oxidative metabolic enzymes – citrate synthase and cytochrome oxidase – but not that of the glycolytic enzyme lactic dehydrogenase. The specific activity of cytochrome oxidase was further stimulated by cold acclimation. Triglycerides and fatty acids were severely depleted in fasted animals, but thermal acclimation had no significant effect on lipid stores. This study illustrates: (1) the differential nature of various metabolic responses to fasting; and (2) the confounding interaction of the nutritional state on thermal acclimation experiments in an ectotherm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00898-998-0001-7
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  • 7
    Electronic Resource
    Electronic Resource
    Hydrogen fluoride effects on plasma membrane composition and ATPase activity in needles of white pine (Pinus strobus) seedlings pretreated with 12 h photoperiod (1997)
    Springer
    Trees 11 (1997), S. 248-253 
    Details
    ISSN: 0931-1890
    Keywords: Key words ATPase ; Fluoride ; Lipids ; Pine ; Plasma membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Eastern white pine (Pinus strobus L.) seedlings were pretreated with 12 h photoperiod to induce dormancy. Dormant plants were fumigated with 0.5 ppb (0.4 μg m–3) or 2.0 ppb (1.6 μg m–3) hydrogen fluoride (HF) for 2 – 28 days. Plasma membranes were isolated from needles of treated and control seedlings to determine their chemical composition and ATPase activity. For all analyses, only those plants which did not show needle necrosis were selected. The amount of plasma membrane phospholipid expressed on a plasma membrane protein basis was higher after 2 days in the 0.5 ppb HF treatment as compared to controls. After 2 days of 2.0 ppb HF treatment as well as after 8 and 28 days of both HF treatments phospholipid to protein ratios in fluoride treated seedlings were lower as compared to control levels. A decrease in sterol levels could be observed after 2 days in both HF treatments. A large increase in the ratio of sterols to proteins was observed in plasma membranes of eastern white pine seedlings treated with 0.5 ppb HF for 28 days. Increased sterol to phospholipid ratios were observed after 8 and 28 days in 0.5 ppb and after 2 and 8 days of 2.0 ppb HF treatment. A decrease in ATPase activity was observed after 8 days with both fluoride treatments. Drastic increase of ATPase activity was observed after 28 days of HF treated plants. Observed changes of sterol and phospholipid levels after only 2 days of fumigation suggest early fluoride effects on plasma membrane composition during plant dormancy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00009671
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  • 8
    Electronic Resource
    Electronic Resource
    Vitamin E stimulates trabecular bone formation and alters epiphyseal cartilage morphometry (1995)
    Springer
    Calcified tissue international 57 (1995), S. 293-300 
    Details
    ISSN: 1432-0827
    Keywords: Vitamin E ; Lipids ; Lipid peroxidation ; Epiphyseal cartilage ; Bone morphometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effects of dietary vitamin E (VIT E) and lipids on tissue lipid peroxidation and fatty acid composition, epiphyseal growth plate cartilage development, and trabecular bone formation were evaluated in chicks. A 2×2 factorial design was followed using two levels (30 and 90 IU/kg of diet) of dl-α-tocopheryl acetate and two different dietary lipids. The basal semipurified diet contained one of the following lipid treatments: anhydrous butter oil (40 g/kg)+ soybean oil (60 g/kg), [BSO], or soybean oil (100 g/kg), [SBO]. After 14 days of feeding, the level of α-tocopherol in plasma was higher and thiobarbituric acid reactive substances (TBARS) were less in plasma and liver of chicks supplemented with 90 IU of VIT E compared with those given 30 IU of VIT E. Body weights and tibiotarsal bone lengths were not affected by the dietary treatments Saturated fatty acids (14:0, 15:0, 16:0, 17:0, and 18:0) were increased in tibiotarsal bone of chicks fed the BSO diet. In contrast, total polyunsaturated fatty acids and the ratio of unsaturated fatty acids/saturated fatty acids were higher in plasma of chicks fed SBO compared with the values from chicks fed BSO. The thickness of the entire growth plate cartilage and the lower hypertrophic chondrocyte zone was significantly greater in chicks fed 90 IU/kg of VIT E. Kinetic parameters on bone histomorphometry indicated that mineral apposition rate was higher in chicks fed 90 IU/kg of VIT E. The interaction effect between the VIT E and BSO treatments led to the highest trabecular bone formation rate among the groups. These data suggest that VIT E protects against cellular lipid peroxidation in cartilage to sustain normal bone growth and modeling.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00298885
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  • 9
    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
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  • 10
    Electronic Resource
    Electronic Resource
    Specific binding of peanut agglutinin to GM1-doped solid supported lipid bilayers investigated by shear wave resonator measurements (1996)
    Springer
    European biophysics journal 25 (1996), S. 105-113 
    Details
    ISSN: 1432-1017
    Keywords: Key words Quartz crystal microbalance (QCM) ; Impedance spectroscopy ; Solid supported lipid bilayers ; Lectins ; Gangliosides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract This study deals with the specific interaction between the lectin peanut agglutinin (PNA) from Arachis hypogaea and the ganglioside GM1 which was incorporated in a solid supported lipid bilayer immobilized on a gold electrode placed on top of an AT-cut quartz crystal. Bilayer formation was reached by self-assembly processes. The first monolayer consists of octanethiol attached to the gold surface via chemisorption and the second monolayer was immobilized by vesicle fusion on the preformed hydrophobic surface. We managed to keep unspecific binding to a minimum by using a phospholipid matrix consisting of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Lectin binding to ganglioside GM1 containing membranes was determined by a decrease of the resonant frequency of the quartz crystal. The minimum amount of receptor within the membrane which is necessary to obtain a complete protein monolayer was found to be less than 2 mol%. The adsorption isotherm of PNA to GM1 was recorded and analyzed to be of Langmuir type, exhibiting a binding constant of PNA to the ganglioside of 8.3 ⋅ 105 M–1. The good agreement of the calculated Langmuir adsorption isotherm with the obtained experimental data implies that protein multilayers are not formed and that interactions between the adsorbents can be neglected. Furthermore, the association constants of two different saccharides, β-Galp-(1 → 3)-GalNAc exhibiting a strong binding to PNA in solution, and β-D-galactose with a much lower affinity were estimated by determining the equilibrium concentration of PNA attached to the surface. Moreover we were able to remove the attached lectin monolayer by digestion of the protein with pronase causing an increase in the resonant frequency which almost reversed the frequency shift to lower frequencies during adsorption. An even more complex system was built up by the use of digoxigenin-labeled PNA which also binds to the solid supported membrane containing the receptor GM1. The immobilized lectin was recognized by anti-digoxigenin-Fab-fragments, which is measurable by a further decrease of the resonant frequency. For all binding processes we found larger frequency shifts for a complete protein monolayer than predicted by Sauerbrey's equation, clearly showing that in addition to mass loading viscoelastic changes occur at the lipid-protein interface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002490050022
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