Log smoldering after an Amazonian deforestation fire

The characteristics of log smoldering after an Amazonian deforestation fire are described. The experiment was carried out in 2001 at the Caiabi farm, near the city of Alta Floresta, state of Mato Grosso, Brazil, as part of a set of tests that have been performed in the same area since 1997. A 200 x 200m(2) test area was slashed in the beginning of June and burned on 20 August. The area contained 507 logs with diameter at breast height (DBH) higher than 10 cm, per hectare. In the day following the main burn 59 logs were found to remain smoldering, a number that corresponds to 2.9% of the total in the area. We chose 11 of the 59 logs to have their smoldering process monitored. Their diameter, moisture content and CHN dry biomass composition after the plot burn and before smoldering were determined. Other parameters such as temperature distribution while smoldering, porosity, density and mass volatilized during thermogravimetric test were also determined. Average smoldering speeds were in the range from 0.8 to 1.5 cm h(-1) for logs that smoldered without transition to the flaming regime. The average speed increased to 2.1 cm h(-1) for those logs that oscillated between smoldering and flaming. The speeds were lower overnight as compared to values determined during daytime for the same log. Higher log moisture contents were found to produce decreased speeds. Micro-porous biomass was not observed in the set of the 11 selected logs. Smoldering was observed to occur at substantial intensity in crossing of logs, with no longitudinal propagation. (C) 2003 Elsevier Ltd. All rights reserved.

Construção de uma câmara para monitoramento in situ do processo de secagem de geis e sólidos porosos

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

SAXS measurements of the porosity in Cu(II)-doped SnO2 xerogels during crystallization

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

β-galactosidase immobilization on controlled pore silica

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

Microstructural characteristics and electrochemical behavior of Co3O4 sintered electrodes

Co3O4 can be used as electrocatalyst for oxygen evolution reaction. The macro and microstructure of the oxide, obtained by compacting and sintering lithium-doped Co3O4 powder in atmosphere of dry air and in conditions of controlled temperature and time was analyzed by metallographic techniques. The porous material was characterized by XRD, SEM and EDS combined techniques. For working temperatures up to 1200°C, the pellet was consituted of particles with varying sizes over a wide range of particle size and, at higher temperatures CoO is formed and polymorphic transformation was observed. The materials were also characterized electrochemically in alkaline media by open circuit potential and potentiodynamic I/E measurements. The results were compared to those previously prepared by others by thermal deposition.

Stagnant effective thermal conductivity of agro-industrial residues for solid-state fermentation

The stagnant effective thermal conductivities (K0) of sugar cane bagasse (SCB), wheat bran (WB), orange pulp and peel (OPP) and their combination (weight proportion 1:2:2 SCB/OPP/WB) were obtained using the line heat source method. These solid materials were applied to pectinase production via solid-state fermentation. The moisture content ranged from 4 to 80% (w.b.). A conduction mechanism through the porous media was observed, along with conduction through a liquid film and contact thermal resistance between the samples and the probe. K0 was low for intermediate moisture contents and approached the molecular conductivity of water for high moisture contents. © 2013 Copyright Taylor and Francis Group, LLC.

Níquel (II) e moléculas orgânicas multidentadas como building blocks na construção de sólidos de coordenação porosos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Desenvolvimento de estruturas porosas de polietileno de ultra alto peso molecular (PEUAPM) recobertas com apatitas para substituição e regeneração óssea

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Aluminas macro-mesoporosas produzidas pelo método sol-gel para aplicação em catálise heterogênea

Pós-graduação em Química - IQ

Síntese de aluminas macro-mesoporosas pelo método sol-gel acompanhado de separação de fases

Pós-graduação em Química - IQ

Estrutura e algumas propriedades ópticas de difenilfosfinatos de terras-raras

Coordination compounds of trivalent lanthanides cations with diphenylphosphinate are originated from direct reaction between a lanthanide salt and diphenylphosphinic acid. These complexes have peculiar and intriguing features, as (i) quickly obtainment through wet process precipitation, (ii) appreciable thermal stability, similar to inorganic phosphates, (iii) polymeric structure, and consequently, (iv) low solubility in both polar and non-polar solvents. Nowadays, coordination polymers are classified as coordination networks or, in case of porous materials, as metal-organic frameworks (MOFs). By this study, we aim to determine some optical properties of rare-earth diphenylphosphinate (RE = La3+, Eu3+, Gd3+, Lu3+) and conduct an updated classification of these compounds, bringing more details of its structure and the possible proposal of new materials with applications in lighting, detection of ionizing radiation and magnetism. The complexes of trivalent rare-earth cation with diphenylphosphinate were prepared by direct mixture of diphenylphosphinic acid with rare-earth metal chloride, both in ethanolic solution. The solution of diphenylphosphinic acid was kept in a beaker under constant stirring with pH measurements of the solution and gadolinium chloride solution was then dripped slowly with the aid of a burette until its complete addition; the following metal:ligand molar ratios were tested: 1:1, 1:2, 1:3, 2:1 e 3:1. The compounds were characterized by spectroscopic and structural techniques. By Fourier Transform Infrared Spectroscopy (FT-IR), it was possible to check the total ionization of diphenylphosphinic acid in synthesized complexes, confirmed by the absence of the band type A, B, C related to ѵ(O-H) of the acid (2663 cm-1, 2168 cm-1, 1684 cm-1), as well as the disappearance of ѵ(P-OH)=961 cm-1. Furthermore, the occurrence of bands shifts of ѵ(POO-) [symmetrical and asymmetrical] of...

Estrutura e algumas propriedades ópticas de difenilfosfinatos de terras-raras

Coordination compounds of trivalent lanthanides cations with diphenylphosphinate are originated from direct reaction between a lanthanide salt and diphenylphosphinic acid. These complexes have peculiar and intriguing features, as (i) quickly obtainment through wet process precipitation, (ii) appreciable thermal stability, similar to inorganic phosphates, (iii) polymeric structure, and consequently, (iv) low solubility in both polar and non-polar solvents. Nowadays, coordination polymers are classified as coordination networks or, in case of porous materials, as metal-organic frameworks (MOFs). By this study, we aim to determine some optical properties of rare-earth diphenylphosphinate (RE = La3+, Eu3+, Gd3+, Lu3+) and conduct an updated classification of these compounds, bringing more details of its structure and the possible proposal of new materials with applications in lighting, detection of ionizing radiation and magnetism. The complexes of trivalent rare-earth cation with diphenylphosphinate were prepared by direct mixture of diphenylphosphinic acid with rare-earth metal chloride, both in ethanolic solution. The solution of diphenylphosphinic acid was kept in a beaker under constant stirring with pH measurements of the solution and gadolinium chloride solution was then dripped slowly with the aid of a burette until its complete addition; the following metal:ligand molar ratios were tested: 1:1, 1:2, 1:3, 2:1 e 3:1. The compounds were characterized by spectroscopic and structural techniques. By Fourier Transform Infrared Spectroscopy (FT-IR), it was possible to check the total ionization of diphenylphosphinic acid in synthesized complexes, confirmed by the absence of the band type A, B, C related to ѵ(O-H) of the acid (2663 cm-1, 2168 cm-1, 1684 cm-1), as well as the disappearance of ѵ(P-OH)=961 cm-1. Furthermore, the occurrence of bands shifts of ѵ(POO-) [symmetrical and asymmetrical] of...

Evaluation of the biocide activity of phosphorylated and sulfophosphorylated resins

Phosphorylated poly(styrene-co-divinylbenzene) copolymers prepared by aromatic electrophilic substitution reaction with PCl3/AlCl3 were reacted with carbon dissulfite in order to introduce sulfophosphorylated groups into copolymers. These modifications were characterized by FTIR, elemental analysis, spectrophotometry, optical and scanning electron microscopy. The antibacterial activities of the phosphorylated and sulfophorylated copolymers were assessed against Escherichia coli ATCC25922 suspensions (10(3)-10(7) cells mL(-1)) using a column system. The unmodified copolymers did not have antibacterial activity against the E. coil suspensions but the phosphorylated and sulfophorylated copolymers showed significant bactericidal action for all E. coli concentrations. The sulfophosphorylated copolymers had higher antibacterial activity than the phosphorylated ones, mainly for high concentrations of E. coli cells. Published by Elsevier B.V.

Synthesis and characterization of implants for bone substitutions made of biomedical apatites containing silicon

In the last decades the development of bone substitutes characterized by a superior biomimetism has become of particular interest, owing to the increasing economic and societal impact of the bone diseases. In the present work of research the development of bone substitutes characterized by improved biomimetism, has been faced in a chemical, structural and morphological perspective. From a chemical point of view, it has been developed the synthesis of hydroxyapatite powders, exhibiting multiple ionic substitutions in both cationic and anionic sites, so to simulate the chemical composition of the natural bone. Particular emphasis has been given to the effect of silicon on the chemical-physical and solubility properties of the obtained hydroxyapatites. From a structural point of view, it has been developed the synthesis of ceramic composite materials, based on hydroxyapatite and calcium silicates, employed both as a reinforcing phase, to raise the mechanical strength of the composite compared to hydroxyapatite, and as a bioactive phase, able to increase the bioactivity properties of the whole ceramic. Finally the unique morphological features of the bone were mimicked by taking inspiration by Nature, so that native wood structures were treated in chemical and thermal way to obtain hydroxyapatite porous materials characterized by the same morphology as the native wood. The results obtained in the present work were positive in all the three different areas of investigation, so to cover the three different aspects of biomimetism, chemical, structural and morphological. Anyway, only at the convergence of the three different fields it is possible to find out the best solutions to develop the ideal bone-like scaffold. Thus, the future activity should be devoted to solve the problems at the borderline between the different research lines, which hamper this convergence and in consequence, the achievement of a bone scaffold able to mimic the various aspects exhibited by the bone tissue