ChemInform Abstract: STUDY ON THE EFFECT OF THE SURROUNDING GAS ATMOSPHERE ON THE ELECTRICAL SURFACE CONDUCTIVITY OF ALL TRANS-β-CAROTENE

1978 ◽  
Vol 9 (8) ◽  
Author(s):  
L. BREHMER ◽  
H. HAENSEL
Keyword(s):  
Surface Conductivity ◽  
Gas Atmosphere ◽  
Β Carotene

Recent Progress In High-Resolution Shadowing For Biological Transmission Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 510-511 ◽  
Author(s):  
Heinz Gross ◽  
Katarina Krusche ◽  
Peter Tittmann
Keyword(s):  
Heavy Metal ◽  
High Resolution ◽  
Freeze Drying ◽  
Atmospheric Conditions ◽  
Vacuum Equipment ◽  
Transmission Electron ◽  
Gas Atmosphere ◽  
Gas Molecules ◽  
Residual Gas ◽  
Backing Layer

Freeze-drying followed by heavy metal shadowing is a long established and straight forward approach to routinely study the structure of dehydrated macromolecules. Very thin specimens such as isolated membranes or single macromolecules are directly adsorbed on C-coated grids. After rapid freezing the grids are transferred into a suitable vacuum equipment for freeze-drying and heavy metal shadowing.To improve the resolution power of shadowing films we introduced shadowing at very low specimen temperature (−250°C). To routinely do that without the danger of contamination we developed in collaboration with Balzers an UHV (p≤10-9 mbar) machine (BAF500K, Fig.2). It should be mentioned here that at −250°C the specimen surface acts as effective cryopump for practically all impinging residual gas molecules from the residual gas atmosphere.Common high resolution shadowing films (Pt/C, Ta/W) have to be protected from alterations due to air contact by a relatively thick C-backing layer, when transferred via atmospheric conditions into the TEM. Such an additional C-coat contributes disturbingly to the contrast at high resolution.

Serum Retinol and β-carotene Levels and Risk Factors for Cardiovascular Disease in Morbid Obesity

2010 ◽  
Vol 80 (3) ◽  
pp. 159-167 ◽  
Author(s):  
Gabriela Villaça Chaves ◽  
Gisele Gonçalves de Souza ◽  
Andréa Cardoso de Matos ◽  
Dra. Wilza Abrantes Peres ◽  
Silvia Elaine Pereira ◽  
...  
Keyword(s):  
Risk Factors ◽  
Cardiovascular Disease ◽  
Metabolic Syndrome ◽  
Morbid Obesity ◽  
Serum Levels ◽  
World Health ◽  
Morbidly Obese ◽  
Serum Retinol ◽  
Significant Difference ◽  
Β Carotene

Objective: To evaluate retinol and β-carotene serum levels and their relationship with risk factors for cardiovascular disease in individuals with morbid obesity, resident in Rio de Janeiro. Methodology: Blood serum concentrations of retinol and β-carotene of 189 morbidly obese individuals were assessed. The metabolic syndrome was identified according to the criteria of the National Cholesterol Education Program (NCEP) and World Health Organization (WHO). Lipid profile, insulin resistance, basal insulin, glycemia, blood pressure, and anthropometry and their correlation with retinol and β-carotene serum levels were evaluated. Results: Metabolic syndrome diagnosis was observed in 49.0% of the sample. Within this percentage the levels of β-carotene were significantly lower when body mass index increased. Serum retinol didn't show this behavior. Serum retinol inadequacy in patients with metabolic syndrome (61.3%), according to WHO criterion, was higher (15.8%) than when the whole sample was considered (12.7%). When metabolic syndrome was diagnosed by NCEP criterion, β-carotene inadequacy was higher (42.8%) when compared to the total sample (37.5%). There was a significant difference between average β-carotene values of patients with and without metabolic syndrome (p=0.048) according to the classification of the NCEP. Lower values were found in patients with metabolic syndrome. Conclusion: Considering the vitamin A contribution in antioxidant protection, especially when risk factors for cardiovascular disease are present, it is suggested that great attention be given to morbidly obese. This could aid in prevention and treatment of cardiovascular disease, which affects a significant part of the population.

Vitamin A Value of Plant Food Provitamin A - Evaluated by the Stable Isotope Technologies

2014 ◽  
Vol 84 (Supplement 1) ◽  
pp. 25-29 ◽  
Author(s):  
Guangwen Tang
Keyword(s):  
Stable Isotope ◽  
Vitamin A ◽  
Provitamin A ◽  
Animal Origin ◽  
Plant Food ◽  
Plant Foods ◽  
A Value ◽  
Provitamin A Carotenoids ◽  
Β Carotene

Humans need vitamin A and obtain essential vitamin A by conversion of plant foods rich in provitamin A and/or absorption of preformed vitamin A from foods of animal origin. The determination of the vitamin A value of plant foods rich in provitamin A is important but has challenges. The aim of this paper is to review the progress over last 80 years following the discovery on the conversion of β-carotene to vitamin A and the various techniques including stable isotope technologies that have been developed to determine vitamin A values of plant provitamin A (mainly β-carotene). These include applications from using radioactive β-carotene and vitamin A, depletion-repletion with vitamin A and β-carotene, and measuring postprandial chylomicron fractions after feeding a β-carotene rich diet, to using stable isotopes as tracers to follow the absorption and conversion of plant food provitamin A carotenoids (mainly β-carotene) in humans. These approaches have greatly promoted our understanding of the absorption and conversion of β-carotene to vitamin A. Stable isotope labeled plant foods are useful for determining the overall bioavailability of provitamin A carotenoids from specific foods. Locally obtained plant foods can provide vitamin A and prevent deficiency of vitamin A, a remaining worldwide concern.

Investigations of the corrosion activity of the KAlCl4 melts by the methods of physicochemical analysis

2019 ◽  
Vol 24 (4) ◽  
pp. 59-66
Author(s):  
E.S. Filatov
Keyword(s):  
Water Vapor ◽  
Hydrochloric Acid ◽  
Input Data ◽  
Corrosion Potential ◽  
Physicochemical Analysis ◽  
Metal Alloys ◽  
Corrosion Activity ◽  
Protection Efficiency ◽  
Gas Atmosphere ◽  
Metal Aluminum

Corrosion behavior of metal alloys in a melt of potassium chloroaluminate (KAlCl4) was investigated. Metal aluminum was used as a protector for protection against continuous frontal corrosion. The equilibrium potentials of aluminum and the corrosion potential of the alloys were measured. The data were obtained to evaluate the corrosion ability of the system of molten salt of potassium chloroaluminate - gas (argon) by measuring the redox potential of the specified environment depending on the composition of the gas atmosphere above it, i.e. from impurities of water vapor, hydrochloric acid, oxygen and other, for example, carbonaceous gases. The calculations of the protection efficiency using the potential difference between the metal aluminum and the protected material were performed. The regularities of changes in the equilibrium potentials of aluminum from the temperature and concentration were established as the fundamental data for possible use at determining the composition ratio of potassium chlorides and aluminum in potassium chloroaluminate as input data for the development of a sensor of composition of chloroaluminate potassium.

Évaluation de la teneur des composés phénoliques, des proprieties antioxydantes et antimicrobiennes de l’espèce Erica arborea L. (Ericaceae) dans la médecine traditionnelle du Tell sétifien dans l’Est Algérien

2019 ◽  
Author(s):  
K. Yaici ◽  
S. Dahamna ◽  
I. Moualek ◽  
H. Belhadj ◽  
K. Houali
Keyword(s):  
Activité Antioxydante ◽  
Activité Antimicrobienne ◽  
Médecine Traditionnelle ◽  
Composés Phénoliques ◽  
Bacillus Subtilus ◽  
Erica Arborea ◽  
Infections Urinaires ◽  
Flavonoïdes Totaux ◽  
Extraits Aqueux ◽  
Β Carotene

Les sommités florales d’Erica arboea L. sont largement utilisées sous forme d’infusion en médecine traditionnelle et sont recommandées dans le Tell sétifien pour traiter et prévenir les infections urinaires aiguës et chroniques principalement. Nous avons soumis les extraits aqueux des feuilles et des fleurs à un dosage des polyphénols, des flavonoïdes et à la détermination des activités antioxydante et antimicrobienne. Les teneurs en composés phénoliques et flavonoïdes totaux ont montré une corrélation avec les activités antioxydantes évaluées. Les tests antioxydants utilisés (DPPH, FRAP, CAT, blanchiment du β-carotène et piégeage du radical hydroxyle) ont montré que le test du DPPH a donné la meilleure activité radicalaire. En outre, l’extrait des feuilles s’est mieux exprimé dans les tests du DPPH, du FRAP et du β- carotène. Les tests de la CAT et le radical hydroxyle ont par contre révélé une activité antioxydante plus importante pour l’extrait de fleurs. Pour l’activité antimicrobienne, on a utilisé la méthode de diffusion en milieu gélosé en ayant recours à la méthode des puits. Les deux extraits ont montré une activité antimicrobienne contre les bactéries à Gram positif Staphylococcus aureus ATCC25923, Bacillus subtilus CLAM20302, Bacillus cereus CLAMH300. L’extrait des feuilles a été plus actif avec une valeur variant de 15 à 23 mm comparé à celui des fleurs (17–18,5 mm). Les valeurs de la concentration minimale inhibitrice ont été trouvées dans une gamme variant de 6,25 à 25 mg/ml pour les extraits des feuilles et des fleurs respectivement. Les résultats de l’étude peuvent enrichir les données existantes et montrent que les feuilles et les fleurs d’Erica arborea L. constituent une source d’agents antioxydants et antibactériens.

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