996 resultados para Organic chemicals


Relevância:

20.00% 20.00%

Publicador:

Resumo:

A newsletter produced by Iowa Department of Agriculture and Land Stewardship about the changes of organic farming and raising livestock in Iowa.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A newsletter produced by Iowa Department of Agriculture and Land Stewardship, this information is all about Iowa growers, what is new, what is going on around Iowa for growing.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Analiza la cantidad de carbon organico y nitrogeno en las costas del norte del Perú en noviembre de 1977

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Calcium carbonate nanofibres are found in numerous terrestrial environments, often associated with needle fibre calcite. This study attempts to mimic the natural system and generate comparable crystalline structures. A comparison of natural and synthesized nanofibre structures, using HRTEM as well as electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI), has demonstrated that this type of nanocrystal can result from precipitation on organic templates, most likely cellulose nanofibres. This study emphasizes the fundamental role of organic templates in the precipitation of calcium carbonate in vadose environments, even at the nanoscale.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The chemical resistance of ceramic tiles is the subject of the European Standard UNE-EN ISO 10545-13. In order to evaluate the effect of aqueous solutions of several chemicals agents on the aspect of the tile surface, this standard establishes a series of tests at room temperature followed by visual inspection. According to this standard the tiles of this study are classified as being of maximum resistance (UHA). However operating conditions can be more aggressive than those detailed in the standard. So, a systematic study has been undertaken. In the present work, the effect of aqueous solutions of several organic and inorganic acids on the tile surface is evaluated. Samples immersed in different solutions are subjected to the following conditions: T= 60º C; pH=2 and to agitation processes. Visual analysis, as well as optical microscopy and scanning electron microscopy (SEM) were performed in order to determine the possible variation of the superficial aspect of tiles. Moreover, atomic absorption spectrophotometry has been used in order to obtain quantitative information concerning the solubility of system M (III)-L (M= Fe; L= H2O or L= ligand). The results obtained show, in all cases, a progressive dissolution of iron oxide precipitates presents in the ceramic body

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Newsletter produced by Iowa Department of Agriculture and Land Stewardship about Organic News in farming.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Newsletter produced by Iowa Department of Agriculture and Land Stewardship about Organic News in farming.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Newsletter produced by Iowa Department of Agriculture and Land Stewardship about Organic News in farming.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Newsletter produced by Iowa Department of Agriculture and Land Stewardship about Organic News in farming.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Newsletter produced by Iowa Department of Agriculture and Land Stewardship about Organic News in farming.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Newsletter produced by Iowa Department of Agriculture and Land Stewardship about Organic News in farming.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The wreck U Pezzo, excavated within the Saint Florent Gulf in northern Corsica was identified as the pink, Saint Etienne, a merchant ship which sank on January 31, 1769. In order to determine the composition of organic materials used to coat the hull or to waterproof different parts of the pink, a study of several samples, using molecular biomarker and carbon isotopic analysis, was initiated. The results revealed that the remarkable yellow coat, covering the outside planks of the ship's bottom under the water line, is composed of sulfur, tallow (of ox and not of cetacean origin) and black pitch which corresponds to a mixture called ``couroi'' or ``stuff'. Onboard ropes had been submitted to a tarring treatment with pitch. Hairs mixed with pitch were identified in samples collected between the two layers of the hull or under the sheathing planking. The study also provides a key model for weathering of pitch, as different degrees of degradation were found between the surface and the heart of several samples. Accordingly, molecular parameters for alteration were proposed. Furthermore novel mixed esters between terpenic and diterpenic alcohols and the free major fatty acids (C(14:0), C(16:0), C(18:0)) were detected in the yellow coat. (C) 2009 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper summarizes data on the factors involved in addiction and dependence to cigarettes. Nicotine has been intensively studied by the tobacco industry, for instance for its addictive effect at the lowest possible rates. The addition of diammonium phosphate and urea produces an alcalinization of the pH of cigarette smoke, and promotes the absorption and the trans-membrane passage of nicotine. The taste, the smell of smoke, and the visual aspect of the pack of cigarettes are also sensory components that promote addiction. Finally, menthol, sugar, cocoa and liquorice added to cigarettes also play a role in dependence and addiction to cigarettes by, for instance, making an anesthetic effect on the airways.