Adding Salt to an Aqueous Solution of t-Butanol: Is Hydrophobic Association Enhanced or Reduced?

Recent neutron scattering experiments on aqueous salt solutions of amphiphilic t-butanol by Bowron and Finney [Phys. Rev. Lett. {\bf 89}, 215508 (2002); J. Chem. Phys. {\bf 118}, 8357 (2003)] suggest the formation of t-butanol pairs, bridged by a chloride ion via ${O}-{H}...{Cl}^-$ hydrogen-bonds, and leading to a reduced number of intermolecular hydrophobic butanol-butanol contacts. Here we present a joint experimental/theoretical study on the same system, using a combination of molecular dynamics simulations and nuclear magnetic relaxation measurements. Both theory and experiment clearly support the more intuitive scenario of an enhanced number of hydrophobic contacts in the presence of the salt, as it would be expected for purely hydrophobic solutes [J. Phys. Chem. B {\bf 107}, 612 (2003)]. Although our conclusions arrive at a structurally completely distinct scenario, the molecular dynamics simulation results are within the experimental errorbars of the Bowron and Finney work.Comment: 15 pages twocolumn revtex, 11 figure

New enzymatic method for the determination of total phenolic content in tea and wine

A new spectrophotometric enzymatic method for the determination of total phenol content in tea and wine has been developed. The method is based on the peroxidase-catalyzed oxidation, by hydrogen peroxide, of phenols to phenoxyl radicals, which can react with aromatic substrates to form intensely colored adducts. In comparison with the widely used Folin-Ciocalteu method, this method appears to be more specific and more rapid and as a whole is not affected by the common interfering substances such as ascorbate, citrate, and sulfite. Numerous samples of teas and wines were analyzed by using the new method, and the results compared with those obtained by using the Folin and scavenging of DPPH methods. The differences of the total phenols content found by applying the three methods are discussed in terms of the different specificities of the analytical basis

La dinámica espaciotemporal de una población multiespecífica de lombrices en un rodal de roble.

We studied the spatial dynamics of endogeic earthworms in a Quercus robur forest. Samples were taken using a 30 point grid every three months during a year plus a summer. Growth rates were estimated for each point based on abundance data. Abundances appeared to be correlated in the direction NW-SE showing a net movement of the organisms to the SE region of the studied field. The migration speed of earthworms was 1.2 m month-1. We fitted the spatial dynamics to several growth mathematical models; the most accurate models were the logistic model of Smith, that is a model with physiological constraints, and the non-symmetric logistic equation, that considers inter-specific competition. The models revealed a significant non-hierarchic diffuse competition and a low rate of individual resource consumption. Moreover, growth rates were high at low population densities but remained roughly constant at densities above 20 individuals m-2.Se estudió la dinámica de una población multiespecífica de lombrices endogeas en un rodal de robles (Quercus robur) tomando muestras en pequeños parches sobre un mosaico. Se tomaron muestras con reposición en una grilla de 30 puntos equidistantes. La frecuencia de muestreo fue estacional (cada tres meses) durante cinco estaciones. A partir de los datos de abundancias se estimaron las tasas de crecimiento en cada punto y se correlacionaron con las abundancias en el mismo punto y en los puntos vecinos para detectar la dirección de máxima correlación que resultó ser NO-SE. La velocidad migratoria media de las lombrices en esa dirección fue de 1.2 m mes-1. Se pusieron a prueba cuatro modelos de dinámica de abundancias; dos de ellos, el modelo logístico de Smith (que incorpora los diferentes requerimientos energéticos según el tamaño individual) y la logística asimétrica (que considera competencia intraespecífica con variación no lineal con la densidad) mostraron un ajuste significativo a los datos, revelando un predominio de competencia difusa no jerárquica, una baja tasa de consumo de recursos por individuo y una tasa de crecimiento muy alta a densidades pequeñas y casi constante a densidades por encima de los 20 individuos m-2

Coelioscopie pour douleur pelvienne: Résultats d.une série de 40 cas

Dans le but d.étudier objectivement les causes des pelvialgies, nous avons, de Janvier 2001 à Novembre 2005 soumis au Centre de Recherche et d.Application en Chirurgie Endoscopique et Reproduction Humaine de Yaoundé (CRACERH), 40 patientes Camerounaises à des coelioscopies de bilan, pour pelvialgie chronique. La moyenne d.âge était de 35,25 ans ± 6,23 (23 . 51) ; il s.agissait de pelvialgie indépendante du cycle chez 36 patientes (90%), de dyspareunie profonde chez 16 patientes (40%) et de dysménorrhée secondaire chez 15 patientes (37,50%). La durée moyenne de la pelvialgie était de 3ans ± 1,5 (1 . 7). Les antécédents de maladie inflammatoire pelvienne à Chlamydia trachomatis, d.avortement septique, et de laparotomie pelvienne étaient retrouvés respectivement dans 55 % (22 cas); 50 % (20 cas); 19 cas (47, 5%). Les pathologies essentiellement rencontrées chez nos patientes, et par ailleurs reconnues algogènes étaient : les adhérences pelviennes (particulièrement utéro-douglaso-annexielles) 77,50% (31 cas), les hydrosalpinx 27,50% (11 cas), l.endométriose 22,50% (9 cas ), les varices pelviennes 22,50% (9 cas ), les kystes ovariens 12,50% (5 cas) et les fibromes utérins 15% ( 6 cas ). Vingt trois patientes (57,5%) étaient porteuses chacune d.au moins 2 pathologies pelviennes algogènes. Cette étude vient témoigner davantage le rôle fondamental de la coelioscopie dans le dépistage, et par conséquent la bonne prise en charge des pelvialgies chroniques. Clinics in Mother and Child Health Vol. 3(1) 2006: 427-43

Nutrient Accumulation in Leaves and Soft Twigs of \u3ci\u3eMoringa oleifera\u3c/i\u3e Lam. at Different Growth Stages in Western Highland of Cameroon

Moringa oleifera belongs to the Moringaceae family and is considered to have its origin in the south of the Himalayan mountains. The species is being introduced into the highland zone of Cameroon. It is a tree which has many valuable properties and it is of great nutritional and scientific interest. The objective of this experiment was to evaluate nutrient composition in leaves and soft twigs of M. oleifera at different growth heights when grown in the Western Highland of Cameroon

Relación entre la abundancia de distintas especies de lombrices de tierra (Annelids, Oligochaeta) y algunos parámetros fisicoquímicos en un suelo típico de la estepa pampeana

Se tomaron muestras de lombrices de tierra en 14 fases de un suelo argiudol típico sobre una superficie total de 250 has. Se midieron 13 parámetros fisicoquímicos y se estudió su relación con la presencia de diferentes especies de lombrices. Los factores que resultaron más útiles en la predicción de las especies de lombrices presentes fueron el pH, el contenido de materia orgánica, el contenido de fósforo asimilable, el contenido de nitrógeno y la resistencia eléctrica de la pasta. De las siete especies halladas, las de los géneros Octolasion y Microscolex mostraron preferencia por los suelos con alto contenido de fósforo asimilable. Todas las especies encontradas son comunes en ambientes sometidos a erturbaciones agrícolas. Aporrectodea caliginosa aparenta ser la especie pionera. La única especie autóctona fue Microscolex dubius.Sampling of earthworms was carried out in a 250 ha field encompassing 14 soil phases belonging to the argiudol type soil. The relation between earthworm species composition and 13 physicochemical parameters was studied. The most important accounting for the presence and abundance of the dfferent endogeic mesohumic earthworms species were pH, soil organic content, assimilable phosphorus, nitrogen, and electric resistance of the paste. Octolasion and Microscolex were the most restricted to high contents of phosphorus and organic matter genera. All species found in the area are common in environments subjected to agricultural disturbance. Aporrectodea caliginosa seems to be the pioneer species. All the earthworms identified in this study were exotic species except Microscolex dubius

Estudo do aproveitamento de quatro resíduos agroindustriais para produção de carvão vegetal.

Resumo. Disponível online. MIPE

Population dynamics of two amphipod species and its relationship with the aquatic vegetation in a Luján river basin microenvironment (Argentina)

Se estudió la dinámica anual de las poblaciones de dos especies de anfípodos en un microambiente de agua dulce del arroyo Las Flores, afluente del río Luján. Hyalella (Mesohyallela) curvispina es un anfípodo herbívoro que se alimenta principalmente de las algas del fitobentos; Hyalella (Mesohyalella) sp. utiliza como refugio a las plantas macrófitas acuáticas y es un carnívoro depredador de Hyalella (M.) curvispina. Las comunidades vegetales del arroyo siguen una dinámica escalonada a lo largo del año, con un máximo de perifiton en junio, de fitobentos en octubre y de macrófitas entre noviembre y febrero. H. (M.) curvispina tiene su mayor densidad (1267 indi- viduos/m2) y su producción secundaria más alta (2225 mg.m-2.mes-1) en coincidencia con el pico de fitobentos de octubre, con cuya abundancia se correlaciona positivamente. Hyalella (Mesohyalella) sp. presenta su abundancia máxima (7067 individuos/m2) y su mayor producción secundaria (1018 g.m-2.mes-1) en enero; ambas cantidades se correlacionan positivamente con la biomasa de macrófitas en el ambiente.The dynamics of two amphi- pod species in a freshwater micro-environment was studied. Samples were taken monthly, during a whole year, from Las Flores stream, a Luján river tributary. Hyalella (Mesohyalella) curvispina is a herbivore and feeds mainly on phytobenthos. Hyalella (Mesohyalella) sp. is a H. (M.) curvispina predator and uses macrophytes as a refuge. Periphyton algal biomass reaches its maximum during June, the phytobenthos biomass reaches its maximum during October, and macrophyte biomass reaches its maximum between November and February. H. (M.) curvispina shows its maximum density (1267 individuals/m2) and its highest secondary production (2225 mg.m-2.month-1) in October coinciding with the phytobenthos. peak in biomass; its density correlates positively with phytobenthos abundance. H. (M.) sp. density (7067 individuals/m2) and secondary production (1018 mg.m-2.month-1) both peak in January. H. (M.) curvispina density is positively correlated with phytobenthos biomass. H. (M.) sp. density, biomass and secondary production are all positively correlated with macrophyte biomass