Determination of microconcentrations of amphibolic minerals in talc by the method of X-RAY diffractometry

An x-ray diffractometry method for determination of amphibole impurities in talc is described. The method is realized on DRON-type diffractometers and allows quantitative evaluation of amphibole at a sensitivity threshold of the instrument in the concentration range of 0.15-4.99%. © 2000 Kluwer Academic/Plenum Publishers

Binding of organic matter into an oxidation-resistant form during the interaction of clay minerals with plant residues

The binding of organic matter by clay minerals was studied in experiments simulating the transformation of clay rock with a high content of dioctahedral 2:1 phases in the soil during its interaction with decomposing plant residues. Using modern methods (X-ray phase analysis, thermal analysis and Fouriertransform IR spectroscopy, and adsorption-luminescence analysis), it was shown that the binding of organic matter into a form resistant to treatment with 30% H2O2 entailed changes in the actual structure of the clay aggregates. Peculiar organic-silicate compositions with their structure disordered along the c* axis were formed, in which organic matter was localized both on the surface of the particles and in the interlayer spaces. © 2010 Pleiades Publishing, Ltd

Irreversible fixation of organic components in labile interspaces as a mechanism for the chemical stabilization of clay-organic structures

The relationship between the fixation of organic matter into a form resistant to oxidative destruction and the actual structure of the clay component was studied in profiles of different-aged chernozemic soils of a filled fortification in the Volga Bulgaria. With the use of modern methods (X-ray phase analysis, laser diffraction granulometry, hyphenated thermal analysis-FT-IR spectroscopy, adsorption-luminescence analysis, and ICP emission spectroscopy), it was shown that the formation of organic-smectite complexes with a disordered c*-axis structure is a universal and usual way for the kinetic stabilization of the system during pedogenesis under forest-steppe conditions. The main aim of the study was to experimentally substantiate this phenomenon. © 2012 Pleiades Publishing, Ltd

Synthetic beta cells for fusion-mediated dynamic insulin secretion

Generating artificial pancreatic beta cells by using synthetic materials to mimic glucose-responsive insulin secretion in a robust manner holds promise for improving clinical outcomes in people with diabetes. Here, we describe the construction of artificial beta cells (AβCs) with a multicompartmental 'vesicles-in-vesicle' superstructure equipped with a glucose-metabolism system and membrane-fusion machinery. Through a sequential cascade of glucose uptake, enzymatic oxidation and proton efflux, the AβCs can effectively distinguish between high and normal glucose levels. Under hyperglycemic conditions, high glucose uptake and oxidation generate a low pH (<5.6), which then induces steric deshielding of peptides tethered to the insulin-loaded inner small liposomal vesicles. The peptides on the small vesicles then form coiled coils with the complementary peptides anchored on the inner surfaces of large vesicles, thus bringing the membranes of the inner and outer vesicles together and triggering their fusion and insulin 'exocytosis'

Determination of microconcentrations of amphibolic minerals in talc by the method of X-RAY diffractometry

An x-ray diffractometry method for determination of amphibole impurities in talc is described. The method is realized on DRON-type diffractometers and allows quantitative evaluation of amphibole at a sensitivity threshold of the instrument in the concentration range of 0.15-4.99%. © 2000 Kluwer Academic/Plenum Publishers

Nitrogen fertilization on off-season corn crop

Pesquisas com a cultura do milho (Zea mays L.) plantado em época normal, em solos argilosos de regiões tropicais, sugerem que as perdas de N do solo pela lixiviação não são significativas. A persistência da forma amoniacal nos solos tropicais tem sido maior que se supunha e, fisiologicamente, foi demonstrado que a absorção de N é mais intensa nos estádios iniciais das plantas. Com o objetivo de avaliar os efeitos do manejo do fertilizante nitrogenado na cultura do milho plantado na época denominada safrinha, foram plantados, em 3 de fevereiro de 1999, em um Latossolo Vermelho-Escuro, textura argilosa, em Jaboticabal, SP, dois híbridos de milho (o simples, C333B e o duplo, C444). Foram aplicados 0, 30, 60 e 90 kg/ha de N (uréia), em duas épocas: no plantio e após a emergência, quando as plantas atingiram cinco a seis folhas. A colheita foi efetuada em 7 de julho de 1999, quando foram avaliadas as características agronômicas e o teor de nutrientes nas folhas. Em relação à época extemporânea, não houve efeito das doses nem da forma de aplicação do N, nas características de rendimento de grãos, massa de mil grãos, índice de colheita, altura das plantas e espigas, número de fileiras de grãos por espiga e número de grãos. Os teores de N, P, K, Ca, Mg, S e Zn, determinados nas folhas do milho, não foram influenciados pelos tratamentos, pois os valores permaneceram dentro das faixas de teores tidos como adequados.Experimental researches conducted with corn (Zea mays L.) on normal season in clay soils of tropical regions suggest that losses of the soil N forms are not significant by lixiviation, because the NH4+ form on the tropical soils is more stable than it was supposed. In addition it was physiologically determined that the N absorption is more intensive in the earlier stages of the plants. To evaluate the proposal of the N fertilization effect on corn cultivated on off-season crop, the sowing of two corn hybrids with genetic differences (single, C333B and double, C444) was done on February 3rd, 1999, on clay soil at FCAVJ-Unesp. Four rates of N (0, 30, 60 and 90 kg/ha), as urea, were applied at two times: sowing and after emergency when the plants were with five to six leaves. The harvest was done on July 7th, 1999, with the evaluation of agronomic characteristics and nutrient content on leaves. There was no effect on rate increase or the timing of application of the N fertilizer, for the agronomic characteristics like grain yield, one thousand grain mass, harvest index, ear and plant height, number of total grains and number of grain rows per ear. The foliar content of N, P, K, Ca, Mg, S and Zn were not influenced by the treatments because the values remained in the adequate rate scale

Binding of organic matter into an oxidation-resistant form during the interaction of clay minerals with plant residues

The binding of organic matter by clay minerals was studied in experiments simulating the transformation of clay rock with a high content of dioctahedral 2:1 phases in the soil during its interaction with decomposing plant residues. Using modern methods (X-ray phase analysis, thermal analysis and Fouriertransform IR spectroscopy, and adsorption-luminescence analysis), it was shown that the binding of organic matter into a form resistant to treatment with 30% H2O2 entailed changes in the actual structure of the clay aggregates. Peculiar organic-silicate compositions with their structure disordered along the c* axis were formed, in which organic matter was localized both on the surface of the particles and in the interlayer spaces. © 2010 Pleiades Publishing, Ltd

Irreversible fixation of organic components in labile interspaces as a mechanism for the chemical stabilization of clay-organic structures

The relationship between the fixation of organic matter into a form resistant to oxidative destruction and the actual structure of the clay component was studied in profiles of different-aged chernozemic soils of a filled fortification in the Volga Bulgaria. With the use of modern methods (X-ray phase analysis, laser diffraction granulometry, hyphenated thermal analysis-FT-IR spectroscopy, adsorption-luminescence analysis, and ICP emission spectroscopy), it was shown that the formation of organic-smectite complexes with a disordered c*-axis structure is a universal and usual way for the kinetic stabilization of the system during pedogenesis under forest-steppe conditions. The main aim of the study was to experimentally substantiate this phenomenon. © 2012 Pleiades Publishing, Ltd

Binding of organic matter into an oxidation-resistant form during the interaction of clay minerals with plant residues

The binding of organic matter by clay minerals was studied in experiments simulating the transformation of clay rock with a high content of dioctahedral 2:1 phases in the soil during its interaction with decomposing plant residues. Using modern methods (X-ray phase analysis, thermal analysis and Fouriertransform IR spectroscopy, and adsorption-luminescence analysis), it was shown that the binding of organic matter into a form resistant to treatment with 30% H2O2 entailed changes in the actual structure of the clay aggregates. Peculiar organic-silicate compositions with their structure disordered along the c* axis were formed, in which organic matter was localized both on the surface of the particles and in the interlayer spaces. © 2010 Pleiades Publishing, Ltd

Binding of organic matter into an oxidation-resistant form during the interaction of clay minerals with plant residues

The binding of organic matter by clay minerals was studied in experiments simulating the transformation of clay rock with a high content of dioctahedral 2:1 phases in the soil during its interaction with decomposing plant residues. Using modern methods (X-ray phase analysis, thermal analysis and Fouriertransform IR spectroscopy, and adsorption-luminescence analysis), it was shown that the binding of organic matter into a form resistant to treatment with 30% H2O2 entailed changes in the actual structure of the clay aggregates. Peculiar organic-silicate compositions with their structure disordered along the c* axis were formed, in which organic matter was localized both on the surface of the particles and in the interlayer spaces. © 2010 Pleiades Publishing, Ltd