Search results for "Sodium"
showing 10 items of 1605 documents
Widespread diminishing anthropogenic effects on calcium in freshwaters
2019
Calcium (Ca) is an essential element for almost all living organisms. Here, we examined global variation and controls of freshwater Ca concentrations, using 440 599 water samples from 43 184 inland water sites in 57 countries. We found that the global median Ca concentration was 4.0 mg L−1 with 20.7% of the water samples showing Ca concentrations ≤ 1.5 mg L−1 , a threshold considered critical for the survival of many Ca-demanding organisms. Spatially, freshwater Ca concentrations were strongly and proportionally linked to carbonate alkalinity, with the highest Ca and carbonate alkalinity in waters with a pH around 8.0 and decreasing in concentrations towards lower pH. However, on a temporal…
Correction des hétérogénéités de champ RF b1+ pour l'optimisation de l'IRM quantitative du sodium dans des aliments réels
2021
Grace aux corrections présentées, des données quantitatives de répartition du sodium sont recueillies sur différents aliments salés pour étudier l'effet matrice (carotte, pâte, viande, pomme de terre), l'effet structure (carotte entière, purée de carotte, potage de carotte) et l'effet moment de salage (pendant la cuisson ou à l'assiette) sur la répartition finale du sel. Dans un second temps ces données seront mises en regard de données de relargage du sodium en bouche et de perception gustative. L'objectif du projet étant de fournir des indications aux familles pour utiliser plus efficacement le sel de table : en préservant leur santé et en respectant leurs attentes gustatives.
Sequential Iron-Catalyzed C(sp2)–C(sp3) Cross-Coupling of Chlorobenzamides/Chemoselective Amide Reduction and Reductive Deuteration to Benzylic Alcoh…
2023
Benzylic alcohols are among the most important intermediates in organic synthesis. Recently, the use of abundant metals has attracted significant attention due to the issues with the scarcity of platinum group metals. Herein, we report a sequential method for the synthesis of benzylic alcohols by a merger of iron catalyzed cross-coupling and highly chemoselective reduction of benzamides promoted by sodium dispersion in the presence of alcoholic donors. The method has been further extended to the synthesis of deuterated benzylic alcohols. The iron-catalyzed Kumada cross-coupling exploits the high stability of benzamide bonds, enabling challenging C(sp2)–C(sp3) cross-coupling with alkyl Grign…
Surface active and emulsifying properties of casein micelles compared to those of sodium caseinate
1999
Emulsions prepared using casein micelles and sodium caseinate as the emulsifying agent are compared. It is found that the ultrastructure of the casein proteins influences the properties of the emulsion.
The Sea Urchin sns Insulator Blocks CMV Enhancer following Integration in Human Cells
2001
Insulators are a new class of genetic elements that attenuate enhancer function directionally. Previously, we characterized in sea urchin a 265-bp-long insulator, termed sns. To test insulator activity following stable integration in human cells, we placed sns between the CMV enhancer and a tk promoter up-stream of a GFP transgene of plasmid or retroviral vectors. In contrast to controls, cells transfected or transduced with insulated constructs displayed a barely detectable fluorescence. Southern blot and PCR ruled out vector rearrangement following integration into host DNA; RNase protection confirmed the enhancer blocking activity. Finally, we demonstrate that two cis-acting sequences, p…
The effect of amphiphilic compounds on the secretion of levansucrase by Zymomonas mobilis
2005
Abstract The effect of some aliphatic (n-butanol to n-hexadecanol) and aromatic (benzyl and phenethyl alcohols), anesthetics (procaine) and surfactants (Tween 20 to Tween 80) on the secretion of levansucrase by the levan-producing strain of Gram-negative ethanologenic bacteria Zymomonas mobilis 113S were examined in this study. During incubation of Z. mobilis cells with sucrose (10 mM) a decrease of the levansucrase activity was observed in the presence of these amphiphilic compounds concomitantly with an increase of a total amount of protein in the medium. Since none of the compounds under study had any effect on enzyme activity in vitro observed structure- and concentration-dependent rela…
Propanediol-1,2-dehydratase and metabolism of glycerol of Lactobacillus brevis
1984
While most strains of heterofermentative lactobacilli and strains of Leuconostoc species contained only traces of a dehydratase reacting with glycerol or propanediol-1,2, three strains of Lactobacillus brevis and one strain of L. buchneri that metabolized glycerol readily in the presence of glucose, contained propanediol-1,2 dehydratase (EC 4.2.1.28). This cobamide requiring enzyme from L. brevis B 18 was partially purified. It reacts with the substrates propanediol-1,2, glycerol and ethanediol-1,2 with the relative activities of about 3:2:1. This ratio remained unchanged throughout the purification procedure. The substrate affinities were measured: propanediol-1,2 K m=0.6 mM, glycerol K m=…
Identification of four distinct subunit types in the unique 6 x 6 hemocyanin of the centipede Scutigera coleoptrata.
1999
We isolated 6 x 6 hemocyanin, dissociated it into subunits, and examined it by electron microscopy. The subunits were separated by native polyacrylamide gel electrophoresis (PAGE), sodium dodecyl sulfate PAGE, and crossed immunoelectrophoresis. Single subunits were isolated by gel cutting from native PAGE and identified as hemocyanin by measuring their ultraviolet spectrum. A total of four distinct hemocyanin subunits were identified, and the subunit pattern of the three electrophoresis systems assigned to each other. The relative proportion of subunits a:b:c:d were 2 : 2 :: 1 as determined by densitometry. Presumably, c and d act as linkers between hexamers.
Transport parameters for aroma compounds through i-carrageenan and sodium alginate-based edible films
2011
In an effort to produce more environmentally friendly materials, renewable and biodegradable biopolymers have been investigated as coating materials. Edible films obtained from i-carrageenan and sodium alginates have good mechanical characteristics, are emulsion stabilizers, and decrease oxygen transfer. The addition of lipids to form emulsified films decreases the water vapour transfer and could be used to encapsulate active substances or aroma compounds. The aim of this work was to measure permeability, sorption and diffusion coefficient of the n-hexanal and D-limonene aroma compounds through emulsified (wf) and non-emulsified (wof) i-carrageenan and sodium alginate-based films to finally…
Production, crystallization and preliminary X-ray analysis of the human integrin alpha1 I domain.
1999
Integrin α1β1 is one of the main collagen receptors in many cell types. A fast large-scale production, purification and crystallization method for the integrin α1 I domain is reported here. The α1 I domain was crystallized using the vapour-diffusion method with a reservoir solution containing a mixture of PEG 4000, sodium acetate, glycerol and Tris–HCl buffer. The crystals beong to the C2 space group, with unit-cell parameters a = 74.5, b = 81.9, c = 37.3 Å, α = γ = 90.0, β = 90.8°. The crystals diffract to 2.0 Å and a 94.2% complete data set to 2.2 Å has been collected from a single crystal with an R merge of 5.8%.