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Registros recuperados: 6
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Adiabatic differential scanning calorimetric study of divalent cation induced DNA - DPPC liposome formulation compacted for gene delivery BABT
Süleymanoglu,Erhan.
Complexes between nucleic acids and phospholipid vesicles have been developed as stable non-viral gene delivery vehicles. Currently employed approach uses positively charged lipid species and a helper zwitterionic lipid, the latter being applied for the stabilization of the whole complex. However, besides problematic steps during their preparation, cationic lipids are toxic for cells. The present work describes some energetic issues pertinent to preparation and use of neutral lipid-DNA self-assemblies, thus avoiding toxicity of lipoplexes. Differential scanning calorimetry data showed stabilization of polynucleotide helix upon its interaction with liposomes in the presence of divalent metal cations. It is thus possible to suggest this self-assembly as an...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Nucleic acid-phospholipid interactions; Divalent cation-induced complex formation; Phase transitions; Microcalorimetry.
Ano: 2004 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132004000600007
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Determination of optimal glucose concentration for microcalorimetric metabolic evaluation of equine spermatozoa BABT
Vasconcelos,André Belico de; Souza,Patrícia Castanheira de; Varago,Fabiana Cristina; Lagares,Monique de Albuquerque; Santoro,Marcelo Matos.
The heat conduction microcalorimeter can be used to evaluate the metabolic rates of the sperm cell. Two ejaculates of four stallions were cooled to +5ºC and checked for sperm motility (bright field microscopy), viability (eosin 3%), functional membrane integrity (hyposmotic swelling test), and heat production (microcalorimetry). Glucose and sperm cell concentrations were determined in order to measure the heat outputs resulting from sperm metabolism. Sperm viability, membrane integrity and sperm motility did not differ among the different glucose concentrations tested. Nevertheless, the highest heat output detected by the microcalorimeter was obtained with 6 mM glucose and 10(8) spermatozoa/mL. Since conduction microcalorimetry offered additional...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Microcalorimetry; Glucose; Spermatozoa; Sperm metabolism; Cell viability; Equine.
Ano: 2009 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-89132009000500010
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Microbial enzymatic activity and thermal effect in a tropical soil treated with organic materials Scientia Agricola
Cenciani,Karina; Freitas,Sueli dos Santos; Critter,Silvana Auxiliadora Missola; Airoldi,Cláudio.
Bacteria and fungi are the most active decomposers of organic materials in soil. They directly affect plant nutrient availability, and chemical and physical properties of soils. This investigation aimed at quantifying the effect of several organic materials on microbial activity of a Rhodic Eutrudox. Soil samples were incubated over a period of 91 days with the following organic materials: cattle manure (CM), earthworm humus (HM), and city sewage sludge from Barueri (BA) and Franca (FR). The activities of cellulase, protease and urease enzymes, the soil microbial carbon content (by fumigation-extraction method) and the exothermal effect were evaluated. Experimental design was randomized and arranged as factorial scheme five treatments x seven samplings...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Enzymes; Biomass carbon; Organic materials; Soil microorganisms; Microcalorimetry.
Ano: 2008 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162008000600016
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Microcalorimetry of the smallest plankton fraction: in search for the sources of heat dissipation IBSS Repository
Mukhanov, V. S.; Kemp, R. B..
Heat production by the plankton pico (0.2 to 2 μm) and femto (<0.2 μm) fractions was measured in the dark using a microcalorimetric method. It was surprisingly found that the femtofraction (FF) produced more heat per seawater volume (48 ± 24 (95% CI) μW l-1) than the picofraction (25 ± 14 μW l-1). Consequently, we tested two hypotheses which could explain the phenomenon through a differentiation between the potential sources of heat in FF: (i) metabolism of ultramicrobacteria, the only living component in the fraction besides the non-metabolizing virioplankton which are unable to produce heat; (ii) extracellular chemical processes in aquatic environments. Results of microcalorimetry and respirometry combined with the use of antimicrobial agents...
Tipo: Journal Contribution Palavras-chave: Microcalorimetry; Heat production; Ultramicrobacteria; Virioplankton; Bacterioplankton; Extracellular enzyme activity; Микрокалориметрия; Теплопродукция; Ультрамикробактерии; Вириопланктон; Бактериопланктон; Внеклеточная ферментативная активность.
Ano: 2005 URL: http://repository.ibss.org.ua/dspace/handle/99011/234
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Thermodynamic Characterization of Humic Acid-surfactant Interaction: New Insights into the Characteristics and Structure of Humic Acids Rev. Bras. Ciênc. Solo
Vergütz,Leonardus; Silva,Luis Henrique Mendes da; Novais,Roberto Ferreira; Silva,Maria do Carmo Hespanhol da; Mageste,Aparecida Barbosa; Silva,Ivo Ribeiro.
ABSTRACT Humic acids (HA) are a component of humic substances (HS), which are found in nearly all soils, sediments, and waters. They play a key role in many, if not most, chemical and physical properties in their environment. Despite the importance of HA, their high complexity makes them a poorly understood system. Therefore, understanding the physicochemical properties and interactions of HA is crucial for determining their fundamental role and obtaining structural details. Cationic surfactants are known to interact electrostatically and hydrophobically with HA. Because they are a very well-known and characterized system, they offer a good choice as molecular probes for studying HA. The objective of this study was to evaluate the interaction between...
Tipo: Info:eu-repo/semantics/article Palavras-chave: Enthalpy; Humic substances; Isothermal titration calorimetry; Macromolecular structure; Microcalorimetry; Supramolecular structure.
Ano: 2015 URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-06832015000601633
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Valeur énergétique de la chair de l'huître Crassostrea gigas estimée par mesures microcalorimétriques et par dosages biochimiques ArchiMer
Heral, Maurice; Deslous Paoli, Jean-marc.
The energetic values measured by the direct method and estimated by biochemical analysis of the annual cycle of ash-free dry weight of two Crassostrea gigas populations, show that the analytic results are inferior by 30% to those obtained by direct evaluation. The mean energetic amount is 4.84 cal.mg-1. Its seasonal variations, from 4.11 to 5.39 cal.mg-l, mainly depend on variations in the values of lipids. The mean conversion factor of lipids is 8.63 cal.mg-!, noticeably different from Brody's (9.45 caI.mg-I). This coefficient varies according to seasons from 7.85 to 9.38 cal.mg'-I. According to the biochemical evaluations, female oysters appear to he more energetic than male oysters when gonads are full. Direct evaluations, on the other hand, show no...
Tipo: Text Palavras-chave: Crassostrea gigas; Microcalorimétrie; Biochimie; Coefficient de conversion des lipide; S Bassin de Marennes-Oléron; Crassostrea gigas; Microcalorimetry; Biochemistry; Conversion factor of lipids; Bay of Marennes-Oleron.
Ano: 1983 URL: http://archimer.ifremer.fr/doc/1983/publication-2953.pdf
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