a simple and mild method for tetrahydropyranylation of alcohols is reported at room temperature using a catalytic amount of 3-methylimidazolinium hydrogensulfate([hmim]hso4) as a green, efficient and reusable catalyst. using solvent-free conditions, non-toxic and inexpensive materials, modest and clean work-up, short reaction times and high yields of the products are the advantages of this method.

A parameter is developed which relates the amino acid composition and subunit size of a protein to the degradative rate in vivo. This parameter was calculated for 11 rat liver proteins and a plot versus the half-lives of these proteins is linear and has a coefficient of correlation of -0.96. Evidence is presented which suggests that the density of excess acidic amino acids on the surface of the...

Chemical composition of plant and animal bodies. Classification, properties and functions of carbohydrates, proteins, fats, mineral and vitamins. The simple chemistry and metabolism of carbohydrates. The simple chemistry and metabolism of proteins The simple chemistry and metabolism of fats. The simple chemistry and metabolism of minerals and vitamins Practicals: Testing of carbohydrates, Acidi...

Extracellular release (ER) by phytoplankton is the major source of fresh dissolved organic carbon (DOC) in marine ecosystems and accompanies primary production during all growth phases. Little is known, so far, on size and composition of released molecules, and to which extent ER occurs passively, by leakage, or actively, by exudation. Here, we report on ER by the widespread and bloomforming co...

Chemical composition of Hibiscus drinks (Koor and Vimto varieties, commercial and traditional, infusions and syrups) was related to sensory evaluation and acceptance. Significant correlations between chemical composition and sensory perception of drinks were found (i.e. anthocyanin content and Hibiscus taste). Consumers (n=160) evaluated drink acceptability on a 9-point verbal hedonic scale. Th...

Immediately following spinal cord injury, further injury can occur through several secondary injury cascades. As a consequence of cell lysis, an increase in extracellular Ca(2+) results in additional neuronal loss by inducing apoptosis. Thus, hydrogels that reduce extracellular Ca(2+) concentration may reduce secondary injury severity. The goal of this study was to develop composite hydrogels c...

The chemical composition of the gland-pad sebum of gerbils of both sexes is analysed using gas-liquid chromatographical and mass spectroscopical techniques and compared with the lipids from distal skin areas. Cholesterol esters, with (omega-1)-methyl-substituted fatty acids as acidic constituents, were shown to occur in the gland-pad sebum of both sexes in high concentrations, whereas cholesta-...

tin(ii)-ion-selective electrode consisting of dibenzo-18-crown-6 (db18c6) as an ionophore inpvc matrix was developed. the influences of membrane composition, selectivity, response time,reversibility and temperature on the electrode performance were investigated. the electrodeshowed a near nernstian response for sn2+ ions over a concentration range from 1.0× 10-6 – 1.0× 10-2 m with a slope of 27...

The composition of the surface layer of 13 low-cost jewelry samples with a high Cd content was analyzed using an energy-dispersive X-ray fluorescence spectrometer (ED XRF). The analyzed jewels were obtained in cooperation with the Czech Environmental Inspectorate. The jewels were leached in two types of artificial sweat (acidic and alkaline) for 7 days. Twenty microliters of the resulting solut...

Tundra adjacent to the gravel Dalton Highway in northern Alaska was examined for effects of 15 yr of chronic road and road dust disturbance. Road effects at a nonacidic site (soil pH 2 5.0) and an acidic site (soil pH < 5.0) were compared to examine differential susceptibility. Overall, effects on vegetation were more pronounced in acidic tundra. Initial substrate pH appears to control the degr...