Search results for "Concentration."
showing 10 items of 1849 documents
Effect of Hormones on Sucrose Uptake and on ATPase Activity of Citrus sinensis L. Osbeck Leaves
1994
Carbohydrate accumulation in young, fully expanded leaves of Citrus sinensis L. Osbeck is affected by the presence of the fruitlet on the shoot. Previous work gave evidence that gibberellins may be involved in this 'fruit effect'. In the present work we have studied the effect of gibberellic acid (GA3) on 14C-sucrose uptake by leaf discs and whether its action could be due to a modulation of the plasma membrane ATPase, which maintains the H+ gradient that drives H+/sucrose co-transport. The effect of GA3 on 14C-sucrose uptake depended on the osmolarity of the assay medium. At 300 mOsm a reduction in the uptake rate was observed. The inhibitory effect of the hormone disappeared after preincu…
Compared regimes of NDVI and Rainfall in semi-arid regions of Africa
2006
International audience; Bi-monthly normalized difference vegetation index (NDVI) at an 8km spatial resolution from the advanced very high resolution radiometers (AVHRR) was used from 1981 to 1995 to analyse the vegetation response to rainfall supply in semi-arid regions of Africa. Within the 200-600 mm annual rainfall belt, for which the apparent NDVI response to rainfall was the strongest, three regions were selected which exhibited different patterns in their NDVI regimes and/or relationships with rainfall. The regions, located in western, southern and eastern Africa, were split into coherent sub-regions in terms of mean regime of photosynthetic activity through a cluster analysis. Overal…
Protein-lipid interactions at the air-water interface.
2010
International audience; Protein−lipid interactions play an important role in a variety of fields, for example in pharmaceutical research, biosensing, or food science. However, the underlying fundamental processes that govern the interplay of lipids and proteins are often very complex and are therefore studied using model systems. Here, Langmuir monolayers were used to probe the interaction of a model protein with lipid films at the air−water interface. The protein β-lactoglobulin (βlg) is the major component in bovine milk serum, where it coexists with the milk fat globular membrane. During homogenization of milk, βlg adsorbs to the interface of lipid fat globules and stabilizes the oil-in-…
Different Dissolution Media Lead to Different Crystal Structures of Talinolol with Impact on Its Dissolution and Solubility
2003
During the performance of dissolution tests with immediate and controlled-release talinolol tablets it was detected that the type of the buffer used as dissolution medium had a strong influence on the solubility and the dissolution behavior of the drug. It was proven that talinolol appeared in different crystal structures with strongly differing solubilities when pure water, acetate, or phosphate buffers were employed as dissolution media. The resulting crystal structures were characterized by means of light microscopy, differential scanning calorimetry, and X-ray powder diffraction. All methods were adjuvant to detect changes in talinolol crystal structures. The different solubility and di…
Combatientes de un nuevo cuño: supervivencia y comunidad en los primeros testimonios del exilio
2009
El artículo describe algunos de los núcleos de sentido que acompañaron a la publicación de los testimonios de supervivientes chilenos en los primeros años del exilio. Especialmente, el modo en que la escritura testimonial fue legitimada por la voz autorizada de importante figuras de la Unidad Popular que convirtió a los supervivientes que aportaban su testimonio de la violencia en ‘combatientes de un nuevo cuño'. El artículo analiza el modo en que los supervivientes respondieron en sus textos a esa expectativa política tratando de resguardar en ellos las concepciones de la experiencia, de la política y de la comunidad que habían vertebrado los compromisos de la ‘vía chilena al s…
Increased acidophilia of eosinophil granules after EDTA treatment
1986
The acidophilic reaction of eosinophil leucocyte granules from human, pig and horse blood smears was investigated by using May-Grünwald-Giemsa staining after previous treatment with EDTA and sodium citrate solutions. The same peak at 530 nm, but absorption values considerably higher than those of controls, were found in eosinophil granules after application of chelating agents, indicating that removal of metal cations could unmask basic groups in these structures.
Analysis of intrapulmonary O2concentration by MR imaging of inhaled hyperpolarized helium-3
1999
Inhalation of hyperpolarized 3He allows magnetic resonance imaging (MRI) of ventilated airspaces.3He hyperpolarization decays more rapidly when interacting with paramagnetic O2. We describe a method for in vivo determination of intrapulmonary O2 concentrations ([O2]) based on MRI analysis of the fate of measured amounts of inhaled hyperpolarized3He in imaged regions of the lung. Anesthetized pigs underwent controlled normoventilation in a 1.5-T MRI unit. The inspired O2 fraction was varied to achieve different end-tidal [O2] fractions ([Formula: see text]). With the use of a specifically designed applicator,3He (100 ml, 35–45% polarized) was administered at a predefined time within single …
Alteration of anion gap during almost total plasma replacement with synthetic colloids in piglets
2000
In ten piglets (body weight 8.2-11.6 kg), acid base, electrolyte and anion gap changes were investigated during almost total plasma replacement with hydroxyethyl starch (HES) and modified fluid gelatin (GEL) in saline solution using a cell saver autotransfusion technique. During the study, there were only moderate acid base changes, but marked disturbances in anion balance. At study end, the mean chloride concentration was significantly higher (mmol/l: normal values 97-108, HES 116 +/- 1.5, GEL 108 +/- 1.1, p0.01) and the mean anion gap was significantly lower in the HES group in comparison to the GEL group (mmol/l: normal values 5-14, HES 3 +/- 1.7, GEL 11.9 +/- 0.9, p0.01). It is conclude…
Azobenzene Polyesters Used as Gate-Like Scaffolds in Nanoscopic Hybrid Systems
2012
The synthesis and characterisation of new capped silica mesoporous nanoparticles for on-command delivery applications is reported. Functional capped hybrid systems consist of MCM-41 nanoparticles functionalised on the external surface with polyesters bearing azobenzene derivatives and rhodamine¿B inside the mesopores. Two solid materials, Rh-PAzo8-S and Rh-PAzo6-S, containing two closely related polymers, PAzo8 and PAzo6, in the pore outlets have been prepared. Materials Rh-PAzo8-S and Rh-PAzo6-S showed an almost zero release in water due to steric hindrance imposed by the presence of anchored bulky polyesters, whereas a large delivery of the cargo was observed in the presence of an esteras…
Thermal potential of ion-exchange membranes and its application to thermoelectric power generation
2016
The low efficiency and high price of thermoelectric semiconductors has generated interest in unconventional forms of thermoelectric materials. In this article, ionic thermoelectricity has been studied with commercial ion-exchange membranes for different aqueous 1:1 electrolytes. The theory of thermal membrane potential has been derived taking into account the ionic heats of transport, the non-isothermal Donnan potentials, the temperature polarization, and the thermally-induced concentration polarization of the electrolyte. Also the generated thermoelectric power has been experimentally studied. The experiments show good agreement with the theory, and suggest ways for systematic improvement …