48 research outputs found
Preparation and characterization of polymeric microspheres for Cr(VI) extraction
Microspheres (MS) from different polymers were prepared using two routes. Route A: process of phase inversion with solutions of polysulfone (PSf) in dichloromethane (DCM) and polyvinylpyrrolidone (PVP) as additive. Different weight ratios of PSf-PVP were used in the MS preparation. Route B: MS were obtained by cross-linking in emulsion using a commercial silicone as raw material. The obtained MS were analysed according to their morphological-structural characteristics and in relation to their Cr(VI) extraction capacity using impregnated MS with Aliquat 336. The results obtained showed that MS prepared with PSf-PVP have both less specific surfaces and relative porosities when the proportion of PVP in the mixture is increased. Extraction tests of ion Cr(VI) indicated that synthesized MS have adequate structural characteristics and interesting adsorptive properties which give rise to impregnating selective extractants. Impregnated microspheres with Aliquat 336 prepared from 2:1 PSf-PVP ratio achieved the highest Cr(VI) extractive performance (92% of Cr extraction for contact time of 60 min) and the best breakthrough point in column tests (up to 10 h in the first cycle).Fil: Ochoa, Nelio Ariel. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Illanes, Cristian Omar. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Marchese, Jose. Universidad Nacional de San Luis. Facultad de Ciencias Fisico Matematicas y Naturales. Departamento de Fisica. Laboratorio de Ciencias de Superficies y Medios Porosos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis; ArgentinaFil: Basualto, C.. Universidad de Chile; ChileFil: Valenzuela, Fernando R.. Universidad de Chile; Chil
Anatomy of a high-silica eruption as observed by a local seismic network: the June 2011 Puyehue–Cordón Caulle event (southern Andes, Chile)
High-silica explosive eruptions are one of the most
dangerous natural phenomena, yet it is unclear which processes are involved
in this infrequent kind of event. We present the first systematic
characterization of near-field seismicity associated with a large high-silica
eruption analyzing data recorded before, during and after the 4 June 2011 rhyolitic eruption of Puyehue–Cordón Caulle Volcanic Complex
(PCCVC). Results of a first-level data processing, developed by the Southern
Andean Volcano Observatory (OVDAS) to monitor unrest and the evolution of
the eruption, are complemented here with the relocation of hypocenters into
a local 1D velocity model, the time series of the b value and the computation of the focal
mechanism. This information allows us to define several phases before and
after the onset of the eruption, describing details of the space–time
evolution of seismicity, defining and characterizing the seismic sources, and
identifying the structural control of the magmatic intrusion and stress
variations during the eruption. Our results illuminate several underlying
processes, with emphasis on the possible role that basement structures had
on the storage, transport and evacuation of magma. Integrating our results
with previous findings based on satellite geodesy and petrology of erupted
materials, we discuss general conceptual models regarding destabilization of
structurally controlled acidic magmatic systems, the pass from unrest to
eruption, and changes in eruptive style and waning phases of eruptions, with
broader implications for monitoring and forecast of violent silicic
eruptions.</p
The physiological effects of hypobaric hypoxia versus normobaric hypoxia: a systematic review of crossover trials
Much hypoxia research has been carried out at high altitude in a hypobaric hypoxia (HH) environment. Many research teams seek to replicate high-altitude conditions at lower altitudes in either hypobaric hypoxic conditions or normobaric hypoxic (NH) laboratories. Implicit in this approach is the assumption that the only relevant condition that differs between these settings is the partial pressure of oxygen (PO2), which is commonly presumed to be the principal physiological stimulus to adaptation at high altitude. This systematic review is the first to present an overview of the current available literature regarding crossover studies relating to the different effects of HH and NH on human physiology. After applying our inclusion and exclusion criteria, 13 studies were deemed eligible for inclusion. Several studies reported a number of variables (e.g. minute ventilation and NO levels) that were different between the two conditions, lending support to the notion that true physiological difference is indeed present. However, the presence of confounding factors such as time spent in hypoxia, temperature, and humidity, and the limited statistical power due to small sample sizes, limit the conclusions that can be drawn from these findings. Standardisation of the study methods and reporting may aid interpretation of future studies and thereby improve the quality of data in this area. This is important to improve the quality of data that is used for improving the understanding of hypoxia tolerance, both at altitude and in the clinical setting
Testosterone insulin-like effects: an in vitro study on the short-term metabolic effects of testosterone in human skeletal muscle cells
Testosterone enables growth and hypertrophy in fusion impaired myoblasts that display myotube atrophy: deciphering the role of androgen and IGF-I receptors
Regulation of mTORC1 by growth factors, energy status, amino acids and mechanical stimuli at a glance
Clinical utility of the Liver Frailty Index for predicting muscle atrophy in chronic liver disease patients with hepatocellular carcinoma
Extraccionde mo (vi) con aminas terciarias en un reactor de membranas liquidas de soporte solido
This communication describes the application of a hollow-fiber-type solid supported liquid membrane technique to the study of recovery and enrichment of molybdenum with Alamine 336 (a long chain tertiary amine) from acid leach residual solution of molybdenite concentrate. It was observed a notorious transport and enrichment of molybdenum ions from feed solution towards receiving strip liquor. The transport of molybdenum through the membrane was greatly influenced by the amine concentration in the organic film and by the addition of a certain amount of NH4NO3 into the stripping agent. Alamine presented a high affinity for Mo(VI) practically being not observed coextraction of all contaminant ions. The transport of metal through the membrane corresponds to a mechanism of mass transfer with chemical reaction, controlled by the extraction reaction of ionic species of molybdenum with the amine salt of Alamine "carrier" via anion exchange. However it is possible to indicate that under certain conditions, the Mo(VI) ions permeation through the organic membrane is expected be a diffusion-controlled process based on metal concentration gradients at both side of membrane. The results communicated in this report confirm the practical feasibility of recovery and enrichment of metals in this extractor using impregnated hollow-fibers-type liquid membrane