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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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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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