Mechanism of the formation and properties of antimony polyphosphate

Formation of antimony polyphosphate using Sb2O3 and/or (NH4)2HPO4 and NH4H 2PO4 as starting materials has been simulated by thermal analysis technique. The elimination of water and ammonia molecules induced by heating leads to the formation of intermediate ammonium polyphosphate, which subsequently reacts with Sb2O3. Morphologically, vitreous Sb(PO3)3 is composed of plaques having irregular shapes. Infrared spectra and NMR study is consistent with tetrametaphosphate anion arrangement. The compound is thermally unstable and may be recommended as a donor of -O-P-O- linkers in the preparation of special phosphate glasses. © 2005 Akadémiai Kiadó, Budapest.

AMMONIUM AND NITRATE IN SOIL AND RATOON SUGARCANE GROWN IN FUNCTION OF NITROGEN ON OXISOL

After harvest, sugarcane residues left on the soil surface can alter nitrogen (N) dynamics in the plant-soil system. In Oxisols, the nitrogen fertilizer applied had its effects on the levels of ammonium and nitrate in the soil, N concentration in the plant leaves, and on the growth and productivity of second ratoon plants. The N rates tested were of 0, 60, 120, 180, and 240 kg ha-1. Each treatment was replicated four times. Four months after the experiment was started, ammonium and nitrate concentration in the soil, N levels in plant leaves, and plant growth were evaluated. Productivity was evaluated 11 months after the experiment was set. By increasing the content of mineral N in soil, plant growth variables reflected differences in the production of stems; however, it did not affect foliar N. The use of leaf analysis was not important to assess the nutritional status of nitrogen in the ratoon sugarcane. Nitrogen concentration in soil was affected by nitrogen fertilization, but not the N content in leaves. The rate of 138 kg N ha-1enabled greater production of sugarcane stalks (140 t ha-1). © 2013 Copyright Taylor and Francis Group, LLC.

Growth of calcium phosphate coating on Ti-7.5Mo alloy after anodic oxidation

Titanium and its alloys are widely used as biomaterials due to their mechanical, chemical and biological properties. To enhance the biocompatibility of titanium alloys, various surface treatments have been proposed. In particular, the formation of titanium oxide nanotubes layers has been extensively examined. Among the various materials for implants, calcium phosphates and hydroxyapatite are widely used clinically. In this work, titanium nanotubes were fabricated on the surface of Ti-7.5Mo alloy by anodization. The samples were anodized for 20 V in an electrolyte containing glycerol in combination with ammonium fluoride (NH4F, 0.25%), and the anodization time was 24 h. After being anodized, specimens were heat treated at 450 °C and 600°C for 1 h to crystallize the amorphous TiO2 nanotubes and then treated with NaOH solution to make them bioactive, to induce growth of calcium phosphate in a simulated body fluid. Surface morphology and coating chemistry were obtained respectively using, field-emission scanning electron microscopy (FEG-SEM), AFM and X-ray diffraction (XRD). It was shown that the presence of titanium nanotubes induces the growth of a sodium titanate nanolayer. During the subsequent invitro immersion in a simulated body fluid, the sodium titanate nanolayer induced the nucleation and growth of nano-dimensioned calcium phosphate. It was possible to observe the formation of TiO2 nanotubes on the surface of Ti-7.5Mo. Calcium phosphate coating was greater in the samples with larger nanotube diameter. These findings represent a simple surface treatment for Ti-7.5Mo alloy that has high potential for biomedical applications. © (2013) Trans Tech Publications, Switzerland.

Development and application of an electronic tongue for detection and monitoring of nitrate, nitrite and ammonium levels in waters

This work presents the first study and development of an electronic tongue analysis system for the monitoring of nitrogen stable species: nitrate, nitrite and ammonium in water. The electronic tongue was composed of an array of 15 potentiometric poly(vinyl chloride) membrane sensors sensitive to cations and anions plus an artificial neural network (ANN) response model. The building of the ANN model was performed in a medium containing sodium, potassium, and chloride as interfering ions, thus simulating real environmental samples. The correlation coefficient in the cross-validation of nitrate, nitrite and ammonium was satisfactory in the three cases with values higher than 0.92. Finally, the utility of the proposed system is shown in the monitoring of the photoelectrocatalytic treatment of nitrate. © 2013 Elsevier B.V.

Estímulo da solubilização de fosfato resultante da co-inoculação de Aspergillus niger e Burkholderia cepacia

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Produção de pellets livres e imobilizados e mecanismo de solubilização de fosfatos inorgânicos por Aspergillus niger

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Efficient Photoelectrochemical Reduction of Nitrite to Ammonium and Nitrogen Containing Gaseous Species Using Ti/TiO2 Nanotube Electrodes

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Inorganic phosphates in juices from different parts of sugarcane stalks (cultivars ctc 9, ctc 15 and ctc 16)

This study aimed to quantify, the inorganic phosphates in sugarcane juice from nodes and internodes of three sugarcane cultivars. The experimental design was a randomized block in factorial scheme 3x2. The main treatments were three sugarcane cultivars and two parts of the stalk (nodes and internodes). The inorganic phosphates contents were determined for each treatment. The results were subjected to variance analysis by the F test; when statistically significant, means were compared by the Tukey test at 5% probability. It is concluded that the three cultivars (CTC 9, CTC 16 and CTC 15) showed similar values regarding the content of inorganic phosphates present in the juice, and these values are considered adequate for a good performance in juice clarification. For the different parts of the stem, differences were observed in the levels of the nutrient studied, which showed a higher concentration in the node than in the internode.

Cover crops affecting levels of ammonium and nitrate in the soil and upland rice development

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Reversibility of Thermal Transitions in Dilute Dioctadecyl-Dimethyl-Ammonium Bromide Vesicles

Dioctadecyl-dimethyl-ammonium bromide (DODAB) vesicles can be characterized by their differential scanning calorimetry (DSC) thermograms comprised of two endotherms at T (s) a parts per thousand 36 A degrees C and T (m) a parts per thousand 45 A degrees C in the heating, ascribed respectively to the subgel-to-gel and gel-to-liquid crystalline transitions, and two exotherms at T'(m) a parts per thousand 40 A degrees C and T'(s) a parts per thousand 16 A degrees C in the cooling, ascribed respectively to the liquid crystalline-to-gel and gel-to-subgel transitions. It has been reported but not proved that the T (m)-transitions, the T'(m)-transitions, the T (s)-transitions, and the T'(s)-transitions are reverse to each other, displaying hystheresis Delta T (m) a parts per thousand 5 A degrees C and Delta T (s) a parts per thousand 20-25 A degrees C, respectively. By investigating the effects of the initial scanning temperature (T (i)) on the transition enthalpies (Delta H (m), Delta H (s), Delta H'(m) and Delta H'(s)), we have seen that these transitions are the reverse to each other and display different kinetics.

Effects on soil chemical attributes and cotton yield from ammonium sulfate and cover crops

Fertilizer use in no-till systems must be aligned with a correct interpretation of soil chemical attributes and crop demands. The objectives of this work were evaluate the effects of pre-sowing application of ammonium sulfate (AS) and of cover crops on the yields and soil chemical attributes of no-till cotton (Gossypium hirsutum L. r. latifolium Hutch) over two harvesting years. The experiment was arranged in randomized complete block design, with the plots in strips, and the variables were three cover crops (Raphanus sativus L., Avena strigosa L. and Avena sativa L.) and four AS doses (0, 150, 300, and 450 kg ha-1) applied over millet dry biomass. The cotton in the experimental plots was manually harvested on April 25, 2007 and April 24, 2008. The soil samples were collected between cotton rows in all plots on May 5, 2007 and May 12, 2008, at depths of 0.0-0.05, 0.05-0.10, and 0.10-0.20 m for soil fertility analyses. The increasing doses of AS induced lower soil pH, and calcium (Ca) and magnesium (Mg) levels in the superficial soil layer, as well as higher exchangeable aluminum (Al) and sulfur (S) levels until a depth of 0.20 m. Seed cotton yields increased with increasing AS doses.

Studies on double selenates. Part 12. Thermal decomposition of ammonium selenate and of double selenates of lanthanide, and yttrium, and ammonium

Thermogravimetry (TG) up to 900°C, differential thermal analysis (DTA) up to 1100°C and gravimetric data up to 1200°C, have been used to study the thermal decomposition of ammonium selenate and of the double selenates of lanthanides, and yttrium, and ammonium. The results provided the composition and thermal stability and also an interpretation of the thermal decomposition mechanisms. © 1994.