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Dinâmica do entumpimento de tubos gotejadores sob aplicação de ferro solúvel, sólidos em suspensão e fitoplâncton; Clogging dynamics of driplines under the application of soluble iron, suspended solids and fitoplankton

Carvalho, Lilian Cristina Castro de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 01/10/2009 Português
Relevância na Pesquisa
36.26%
Este projeto de pesquisa foi desenvolvido visando quantificar possíveis distúrbios de vazão em emissores gotejadores submetidos à aplicação de ferro solúvel, sólidos em suspensão (partículas de solo) em águas contendo material orgânico (fitoplâncton/algas), com o orifício dos emissores posicionados para baixo e para cima. Foram realizados dois experimentos A e B em um período de 12 meses, utilizando-se 16 modelos de tubos gotejadores novos e 26 modelos de tubos gotejadores em uso, com suas respectivas linhas gotejadoras montadas em uma bancada de ensaios em estrutura metálica localizada no Laboratório de Irrigação, da Escola Superior de Agricultura Luiz de Queiroz - ESALQ/USP. No experimento A realizou-se 4 tratamentos (T1, T2, T3 e T4), divididos em duas fases, onde na fase 1 avaliou-se a susceptibilidade de diferentes tubos gotejadores ao entupimento por ferro solúvel via duas qualidades de água de irrigação (com e sem carga orgânica) e na fase 2, avaliou-se a susceptibilidade de diferentes tubos gotejadores ao entupimento por aplicação de ferro solúvel, carga orgânica (fitoplâncton/algas) e sólidos em suspensão, com os emissores posicionados para cima e para baixo, ainda na fase 2 aplicou-se uma solução concentrada...

Degradação de fármacos em água pelo acoplamento dos processos ferro zero e Fenton; Degradation of Aqueous Pharmaceuticals by Coupling Zero Valent Iron and Fenton Processes

Fornazari, Ana Luiza de Toledo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 27/02/2015 Português
Relevância na Pesquisa
36.29%
Atualmente, um dos tópicos mais relevantes da Química Ambiental é a qualidade da água. A preocupação com micropoluentes, poluentes que estão presentes no meio ambiente em con-centrações de μg L-1 a ng L-1, tem aumentado recentemente. O objetivo deste trabalho foi estudar a degradação de antibióticos de duas classes: norfloxacina (fluoroquinolona), sulfati-azol e sulfametazina (sulfonamidas) e o anti-inflamatório não esteroide diclofenaco de sódio pelo acoplamento do Processo Ferro Zero, com nanopartículas de Fe0 ou lã de aço comercial, ao Processo Fenton. Teve-se como metas a identificação de produtos de degradação, a avali-ação da ecotoxicidade (Lactuca sativa) e da atividade antimicrobiana (Escherichia coli). Os experimentos de degradação foram realizados via planejamento fatorial 22 com a finalidade de se determinar os efeitos dos parâmetros reacionais (pH e vazão) sobre o desempenho do Processo Ferro Zero. As partículas de Fe0 sintetizadas foram nanométricas (< 100 nm), verificou-se a sua morfologia esférica e constatou-se a presença de Fe0, óxidos de ferro e hidróxidos de ferro. O Processo Ferro Zero em meio óxico, utilizando as NPFe0 ou a lã de aço comercial, obteve remoções de 31...

Lipid peroxidation, antioxidant enzymes and glutathione levels in human erythrocytes exposed to colloidal iron hydroxide in vitro

Ferreira, A.L.A.; Machado, P.E.A.; Matsubara, L.S.
Fonte: Associação Brasileira de Divulgação Científica (ABRADIC) Publicador: Associação Brasileira de Divulgação Científica (ABRADIC)
Tipo: Artigo de Revista Científica Formato: 689-694
Português
Relevância na Pesquisa
56.65%
The free form of the iron ion is one of the strongest oxidizing agents in the cellular environment. The effect of iron at different concentrations (0, 1, 5, 10, 50, and 100 µM Fe3+) on the normal human red blood cell (RBC) antioxidant system was evaluated in vitro by measuring total (GSH) and oxidized (GSSG) glutathione levels, and superoxide dismutase (SOD), catalase, glutathione peroxidase (GSH-Px) and reductase (GSH-Rd) activities. Membrane lipid peroxidation was assessed by measuring thiobarbituric acid reactive substance (TBARS). The RBC were incubated with colloidal iron hydroxide and phosphate-buffered saline, pH 7.45, at 37oC, for 60 min. For each assay, the results for the control group were: a) GSH = 3.52 ± 0.27 µM/g Hb; b) GSSG = 0.17 ± 0.03 µM/g Hb; c) GSH-Px = 19.60 ± 1.96 IU/g Hb; d) GSH-Rd = 3.13 ± 0.17 IU/g Hb; e) catalase = 394.9 ± 22.8 IU/g Hb; f) SOD = 5981 ± 375 IU/g Hb. The addition of 1 to 100 µM Fe3+ had no effect on the parameters analyzed. No change in TBARS levels was detected at any of the iron concentrations studied. Oxidative stress, measured by GSH kinetics over time, occurs when the RBC are incubated with colloidal iron hydroxide at concentrations higher than 10 µM of Fe3+. Overall, these results show that the intact human RBC is prone to oxidative stress when exposed to Fe3+ and that the RBC has a potent antioxidant system that can minimize the potential damage caused by acute exposure to a colloidal iron hydroxide in vitro.

Characterization of iron(III)porphyrin-hydroxo complexes in organic media through UV-Vis and EPR spectroscopies

Manso, CMCP; Neri, C. R.; Vidoto, E. A.; Sacco, H. C.; Ciuffi, K. J.; Iwamoto, L. S.; Iamamoto, Y.; Nascimento, O. R.; Serra, O. A.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 85-92
Português
Relevância na Pesquisa
36.28%
The interaction of OH- with Fe(TPP)(+), Fe(TDCPP)(+), Fe(TMP)(+) and Fe(TFPP)(+) in 1,2-dichloroethane was studied by titrating FeP solutions with aliquots of a solution of tetrabutylammonium hydroxide in acetonitrile. The number of OH- ions (n) coordinated to the FeP and the stability constants (beta(n)) for the FeP-OH- complexes were calculated from UV-Vis absorbance data and iron spin states were determined through EPR spectroscopy, Fe(TMP) (+) forms a high-spin mono-hydroxo complex, while Fe(TPP)I and Fe(TDCPP)(+) form high-spin bis-hydroxo complexes. To our knowledge, this is the first time that the formation of bis-hydroxo complexes from Fe(TPP) (+) has been reported, and this was possible because the studies were carried out in basic organic media, In this same medium, Fe-III-Fe-II reduction upon OH- addition to Fe(TFPP) (+) was observed, without concomitant formation of the mu-oxo dimeric species [Fe(TFPP)](2)O. (C) 1999 Elsevier B.V., All rights reserved.

Mössbauer spectroscopic study of the early crystallization stage of iron(III) hydroxide particles

Conforto, E.; Rechenberg, H. R.; Jafelicci, M.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 1179-1184
Português
Relevância na Pesquisa
46.6%
Mössbauer spectroscopy was used to investigate the early aging stage of iron(III) hydroxide sols prepared by oxidation of Fe(CO)5 in ethanolic solution, followed by vacuum drying at room temperature. One sample was composed of amorphous particles, while two other samples were partially crystallized, either as a result of solvent change or of spontaneous aging. The main results of Mössbauer measurements in the 80-320 K temperature range are: (a) partially crystallized particles exhibit a strong, S-shaped temperature dependence of the quadrupole splitting, in contrast to a weak and linear variation for amorphous particles; (b) the recoilless fraction temperature dependence is affected by vibration of the particles as a whole, with an effective force constant which is smaller for crystallized particles than for amorphous ones. Furthermore, the former exhibit anf-factor discontinuity near 0°C, which is attributed to melting of a surface layer built up during the crystallization process. © 1986.

Caracterização e propriedades do material coloidal nanoestruturado β-FeOOH/bentonita

Anaissi,Fauze Jacó; Villalba,Juan Carlo; Fujiwara,Sérgio Toshio; Cótica,Luiz Fernando; Souza,Cláudio Roberto Lima de; Zamora-Peralta,Patrício
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2009 Português
Relevância na Pesquisa
36.28%
A new mixed material was obtained through the combination of the suspensions of iron oxy-hydroxide and bentonite clay, denoted BFe. Analysis of its structure (XRD, Mossbauer and TGA) and composition (AAS) suggests the maintenance of the layer structure of the clay and an increase in the thermal stability of the BFe. Electrochemical studies performed in different electrolytes show that only in an alkaline medium it is possible to observe the redox peaks relative to the processes involving Fe+2/Fe+3 pair. Tests that evaluated the potential use of the photo-Fenton process showed an efficient degradation process of the dyes in significantly reduced reaction times.

Lipid peroxidation, antioxidant enzymes and glutathione levels in human erythrocytes exposed to colloidal iron hydroxide in vitro

Ferreira,A.L.A.; Machado,P.E.A.; Matsubara,L.S.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/1999 Português
Relevância na Pesquisa
56.65%
The free form of the iron ion is one of the strongest oxidizing agents in the cellular environment. The effect of iron at different concentrations (0, 1, 5, 10, 50, and 100 µM Fe3+) on the normal human red blood cell (RBC) antioxidant system was evaluated in vitro by measuring total (GSH) and oxidized (GSSG) glutathione levels, and superoxide dismutase (SOD), catalase, glutathione peroxidase (GSH-Px) and reductase (GSH-Rd) activities. Membrane lipid peroxidation was assessed by measuring thiobarbituric acid reactive substance (TBARS). The RBC were incubated with colloidal iron hydroxide and phosphate-buffered saline, pH 7.45, at 37oC, for 60 min. For each assay, the results for the control group were: a) GSH = 3.52 ± 0.27 µM/g Hb; b) GSSG = 0.17 ± 0.03 µM/g Hb; c) GSH-Px = 19.60 ± 1.96 IU/g Hb; d) GSH-Rd = 3.13 ± 0.17 IU/g Hb; e) catalase = 394.9 ± 22.8 IU/g Hb; f) SOD = 5981 ± 375 IU/g Hb. The addition of 1 to 100 µM Fe3+ had no effect on the parameters analyzed. No change in TBARS levels was detected at any of the iron concentrations studied. Oxidative stress, measured by GSH kinetics over time, occurs when the RBC are incubated with colloidal iron hydroxide at concentrations higher than 10 µM of Fe3+. Overall, these results show that the intact human RBC is prone to oxidative stress when exposed to Fe3+ and that the RBC has a potent antioxidant system that can minimize the potential damage caused by acute exposure to a colloidal iron hydroxide in vitro.

An enhanced electrochemical sensing platform integrated with graphene oxide and iron hydroxide colloid for sensitive determination of phloroglucinol

Li,Junhua; Kuang,Daizhi; Feng,Yonglan; Liu,Mengqin; Zhang,Fuxing; Deng,Peihong
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2013 Português
Relevância na Pesquisa
66.46%
A novel electrochemical sensing platform was fabricated with nanohybrid consisting of graphene oxide and iron hydroxide colloid. With high surface area and excellent electrical conductivity of the nanohybrid, the prepared electrochemical sensor exhibited preeminent electrocatalytic activity towards the oxidation of phloroglucinol, resulting in the increase of the oxidation peak current and decrease of the oxidation overpotential. The nanohybrid was used as an enhanced electrochemical sensing platform for sensitive determination of phloroglucinol. The oxidation mechanism of phloroglucinol at this sensing platform was investigated in detail, the determination conditions were optimized, and the kinetic parameters were also calculated. Under the optimized conditions, the oxidation peak current was proportional to phloroglucinol concentration in the range from 5.00 to 100.00 nmol L-1 with limits of detection and of quantification of 3.45 and 11.51 nmol L-1, respectively. This sensing platform displayed long-term stability, high reproducibility and super anti-interference capability. It was employed to detect phloroglucinol in environmental water samples with good recoveries. The excellent performance, operational simplicity and low expense make the graphene-based hybrid attractive in the sensor construction.

Iron removal by precipitate flotation

Morosini,Denise Fontoura; Baltar,Carlos Adolpho Magalhães; Duarte-Coelho,Antonio Carlos
Fonte: Escola de Minas Publicador: Escola de Minas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2014 Português
Relevância na Pesquisa
46.29%
The water from several artesian wells in the metropolitan area of Recife presents high iron content, preventing its use in some industrial processes. The possibility of removing the iron by the use of precipitate flotation using sodium dodecyl sulphate (SDS) as collector was studied. The tests were carried out in a glass column 65 cm high, fed by a constant airflow. At pH 8, where the isoelectric point of colloidal iron hydroxide [Fe(OH)3] was observed, the size of the precipitate increases with conditioning time and facilitates the removal of iron ions by flotation. The results showed that an increase in conditioning time, from 5 to 20 minutes, resulted in a reduction of the residual concentration of iron from 13.2 to 0.2 ppm. The decrease in precipitate specific surface area rendered a decrease in the collector consumption possible. The iron ion removal process by flotation using SDS as collector was shown to be quite efficient. A removal of 99% of Fe3+ contained in the original solution was obtained.

THE NATURE OF STORAGE IRON IN IDIOPATHIC HEMOCHROMATOSIS AND IN HEMOSIDEROSIS : ELECTRON OPTICAL, CHEMICAL, AND SEROLOGIC STUDIES ON ISOLATED HEMOSIDERIN GRANULES

Richter, Goetz W.
Fonte: The Rockefeller University Press Publicador: The Rockefeller University Press
Tipo: Artigo de Revista Científica
Publicado em 30/09/1960 Português
Relevância na Pesquisa
36.22%
Using three different methods of cells fractionation, hemosiderin granules were isolated from tissues (liver and/or spleen) of three patients. The samples were obtained from a case of idiopathic hemochromatosis, a case of thalassemia major with secondary (transfusional?) hemosiderosis, and a case of transfusional hemosiderosis associated with an unclassified anemia. Iron, nitrogen, and protein content of the hemosiderin granules varied over a wide range. Electron microscopy of sectioned granules revealed aggregates of dense particles of different shapes, with diameters ranging from 10 A to about 75 A. In some of the granules dense particles corresponding to the iron hydroxide micelles of ferritin molecules were abundant. But many of the granules contained very few of these molecules. The presence of ferritin and apoferritin in the samples of hemosiderin granules was demonstrated by means of precipitin tests in agar-gel, using rabbit antiferritin sera with known antibody nitrogen concentrations. At least three antigenic components were detected in highly purified crystalline ferritin prepared from tissues of the three patients; the hemosiderin granules contained the same antigens, but probably in much smaller quantities. Both ferritin and apoferritin molecules were extracted from hemosiderin granules...

Efficacy, Tolerability, and Acceptability of Iron Hydroxide Polymaltose Complex versus Ferrous Sulfate: A Randomized Trial in Pediatric Patients with Iron Deficiency Anemia

Yasa, Beril; Agaoglu, Leyla; Unuvar, Emin
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.22%
Iron polymaltose complex (IPC) offers similar efficacy with superior tolerability to ferrous sulfate in adults, but randomized trials in children are rare. In a prospective, open-label, 4-month study, 103 children aged >6 months with iron deficiency anemia (IDA) were randomized to IPC once daily or ferrous sulfate twice daily, (both 5 mg iron/kg/day). Mean increases in Hb to months 1 and 4 with IPC were 1.2 ± 0.9 g/dL and 2.3 ± 1.3 g/dL, respectively, (both P = 0.001 versus baseline) and 1.8 ± 1.7 g/dL and 3.0 ± 2.3 g/dL with ferrous sulfate (both P = 0.001 versus baseline) (n.s. between groups). Gastrointestinal adverse events occurred in 26.9% and 50.9% of IPC and ferrous sulfate patients, respectively (P = 0.012). Mean acceptability score at month 4 was superior with IPC versus ferrous sulfate (1.63 ± 0.56 versus 2.14 ± 0.75, P = 0.001). Efficacy was comparable with IPC and ferrous sulfate over a four-month period in children with IDA, but IPC was associated with fewer gastrointestinal adverse events and better treatment acceptability.

Colloid stability of iron compounds in groundwater of Western Siberia

Shiyan, Ludmila N; Tropina, Elena А; Machekhina, Ksenia I; Gryaznova, Elena N; An, Vladimir V
Fonte: Springer International Publishing Publicador: Springer International Publishing
Tipo: Artigo de Revista Científica
Publicado em 22/05/2014 Português
Relevância na Pesquisa
36.35%
The paper reports on experimental modeling of the colloid system composition in natural groundwater. Iron hydroxide is found to be the main component of natural colloid systems. It is shown that silicon compounds and dissolved organic substances (DOS) stabilize iron hydroxide (III), forming a stable colloid system, and preclude coagulation. The presented results suggest that CaCl2 and AlCl3 electrolytes affect the coagulation stability of synthesized model colloid solutions.

Nanoparticulate iron(III) oxo-hydroxide delivers safe iron that is well absorbed and utilised in humans

Pereira, Dora I.A.; Bruggraber, Sylvaine F.A.; Faria, Nuno; Poots, Lynsey K.; Tagmount, Mani A.; Aslam, Mohamad F.; Frazer, David M.; Vulpe, Chris D.; Anderson, Gregory J.; Powell, Jonathan J.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /11/2014 Português
Relevância na Pesquisa
36.59%
Current oral treatment of iron deficiency anaemia is based upon soluble iron compounds, all of which have undesirable gastrointestinal effects. However, natural dietary iron (III) may be nano-formed ligand-modified iron hydroxide particles that are acquired endocytically and thus not soluble or available for adverse effects. Here, a series of five different nano Fe(III) hydroxide particles was developed: absorption in humans matched endocytic uptake by gut epithelial cells but not solubility in (stomach) acid. In murine and cellular models nano iron(III) treated iron deficiency anaemia as well as ferrous sulfate but, unlike the latter, was safe to the gut environment.

Alginate-Iron Speciation and Its Effect on In Vitro Cellular Iron Metabolism

Horniblow, Richard D.; Dowle, Miriam; Iqbal, Tariq H.; Latunde-Dada, Gladys O.; Palmer, Richard E.; Pikramenou, Zoe; Tselepis, Chris
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 17/09/2015 Português
Relevância na Pesquisa
36.33%
Alginates are a class of biopolymers with known iron binding properties which are routinely used in the fabrication of iron-oxide nanoparticles. In addition, alginates have been implicated in influencing human iron absorption. However, the synthesis of iron oxide nanoparticles employs non-physiological pH conditions and whether nanoparticle formation in vivo is responsible for influencing cellular iron metabolism is unclear. Thus the aims of this study were to determine how alginate and iron interact at gastric-comparable pH conditions and how this influences iron metabolism. Employing a range of spectroscopic techniques under physiological conditions alginate-iron complexation was confirmed and, in conjunction with aberration corrected scanning transmission electron microscopy, nanoparticles were observed. The results infer a nucleation-type model of iron binding whereby alginate is templating the condensation of iron-hydroxide complexes to form iron oxide centred nanoparticles. The interaction of alginate and iron at a cellular level was found to decrease cellular iron acquisition by 37% (p < 0.05) and in combination with confocal microscopy the alginate inhibits cellular iron transport through extracellular iron chelation with the resulting complexes not internalised. These results infer alginate as being useful in the chelation of excess iron...

Dissolution of fine and intermediate sized galena particles and their interactions with iron hydroxide colloids

Peng, Y.; Grano, S.
Fonte: Academic Press Inc Elsevier Science Publicador: Academic Press Inc Elsevier Science
Tipo: Artigo de Revista Científica
Publicado em //2010 Português
Relevância na Pesquisa
46.28%
Yongjun Peng, Stephen Grano

Comparative Study of Different Iron Compounds in Inhibition of Sphaerotilus Growth

Chang, Yueh; Pfeffer, John T.; Chian, Edward S. K.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1979 Português
Relevância na Pesquisa
36.52%
The effectiveness of iron compounds on growth inhibition of Sphaerotilus species was compared. In this study, two strains of Sphaerotilus were tested with different iron concentrations in a synthetic sewage (S-medium) as formulated by Lackey and Wattie (Sewage Works J. 12:669-684, 1940). For both strains, >80% inhibition of the maximum respiration rate was obtained by the following levels of soluble iron concentrations at pH 6.0: iron citrate, 20 mg/liter as Fe; iron cysteine, 5 mg/liter as Fe; and ferrous sulfate, 10 mg/liter as Fe. At a pH of 6.7 with iron citrate (20 mg/liter as Fe), inhibition of both strains was in excess of 50%. Insoluble iron compounds, such as iron hydroxides and ferrous carbonate, were found to be much less effective than the soluble iron compounds as inhibitors of these two strains. Aged iron hydroxide (500 mg/liter as Fe) produced a 70% inhibition in the maximum respiration rate while fresh iron hydroxide (52 mg/liter as Fe) and ferrous carbonate (500 mg/liter as Fe) produced a 20% inhibition. Chemical analyses of the iron-inhibited Sphaerotilus strains showed a close relationship between the inhibition of the organism's growth and the amount of iron sorbed by the organism.

Engineering Iron Oxide Nanoparticles For Angiogenic Therapies

Carenza, Elisa; Rodriguez Viejo, Javier
Fonte: [Barcelona] : Universitat Autònoma de Barcelona, Publicador: [Barcelona] : Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis; info:eu-repo/semantics/publishedVersion
Publicado em //2014 Português
Relevância na Pesquisa
36.26%
El trabajo de investigación se ha desarrollado conjuntamente en el Instituto de Ciencia de Materiales de Barcelona (ICMAB-CSIC) y en el Instituto de Investigación del Hospital Universitario Vall d'Hebron (VHIR) en Barcelona. El trabajo se enmarca dentro del contexto tanto de nanomateriales como de nanomedicina. El objetivo principal de la tesis doctoral es desarrollar materiales para terapias no invasivas encaminadas a potenciar la regeneración de vasos sanguinos después de un evento isquémico. Para ello se han utilizado nanopartículas magnéticas de oxido de hierro como instrumentos de visualización ("imaging" por resonancia magnética) y de acumulación de proteínas/células en tejidos específicos bajo la influencia de un campo magnético externo. Se han desarrollado dos estrategias: la primera introduciendo las nanopartículas magnéticas en células endoteliales progenitora y la segunda en nanocápsulas poliméricas junto a un factor de crecimiento vascular. La tesis está estructurada en seis capítulos: CAPÍTULO 1 Las nanopartículas superparamagnéticas de óxido de hierro (SPIONs) son conocidas en diagnosis clínico por utilizarse como agentes de contraste que permiten la visualización de los tejidos a través de resonancia magnética (MRI). El capítulo contiene una breve introducción a la nanotecnología y una presentación de las características magnéticas de los materiales. Además contiene una revisión de los métodos de síntesis de las nanopartículas superparamagnéticas de oxido de hierro. CAPÍTULO 2 Describe la síntesis de nanopartículas superparamagnéticas de oxido de hierro mediante dos técnicas: descomposición térmica y microonda. Ambos métodos nos permiten de obtener partículas monodispersas con tamaño inferior a 20 nm y con excelentes propiedades magnéticas. Se ha logrado estabilizar las partículas en agua y en distintos medios celulares mediante estabilizantes iónicos (hidróxido de tetrametilamonio y sodio citrato). CAPÍTULO 3 La isquemia cerebral se define como la obstrucción de arterias intracraneales...

The Effect of Solution Speciation on Iron-Sulphur-Arsenic-Chloride Systems at 298K

Welham, N; Malatt, K; Vukcevic, S
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
46.22%
The speciation in solution of a number of metallurgically important iron-bearing systems are calculated from critically reviewed data. In acidic solution, Fe2+ and Fe3+ are the predominant iron species, although ferric ion hydrolyzes to Fe(OH)2+ above pH

Ultrastructural changes in hepatic sinusoidal endothelial cells acutely exposed to colloidal iron

Bassett, Mark; Dahlstrom, Jane; Taylor, Matthew; Koina, Mark; Maxwell, Lesley; Francis, Doug; Jain, Sanjiv; McLean, Allan
Fonte: Urban & Fischer Verlag Publicador: Urban & Fischer Verlag
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
36.27%
Hepatic sinusoidal endothelial cells form an important interface between the vascular system, represented by the sinusoids, and the space of Disse that surrounds the hepatocyte microvilli. This study aimed to assess the light microscopic and ultrastructural effects of acute exposure of hepatic sinusoidal endothelial cells to colloidal iron by injection of rats with iron polymaltose. Eight minutes after a single intravenous injection of iron polymaltose sinusoidal endothelial cells showed defenestration, and thickening and layering as assessed by transmission electron microscopy. Kupffer cells and stellate cells appeared activated. These changes were not observed in control animals, experiments using equivalent doses of maltose, or experiments using colloidal carbon except for Kupffer cell activation due to colloidal carbon. No significant light microscopic changes were seen in study or control animals. The findings indicate that acute exposure to colloidal iron causes changes in hepatic sinusoidal endothelial cells, stellate cells and Kupffer cells. This may be the result of a direct toxic effect of iron or increased production of reactive oxygen species. These observations suggest a possible mechanism for defenestration of sinusoidal endothelial cells in ageing and in disease states.

Application of magnesium hydroxide and barium hydroxide for the removal of metals and sulphate from mine water

Bologo,V; Maree,JP; Carlsson,F
Fonte: Water SA Publicador: Water SA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2012 Português
Relevância na Pesquisa
36.45%
The proposed magnesium-barium-oxide process consists of metal removal with Mg(OH)2, magnesium and sulphate removal with Ba(OH)2 and calcium removal with CO2. The raw materials, Mg(OH)2 and Ba(OH)2 are recovered from the BaSO4 and Mg(OH)2 sludges that are produced. Laboratory studies showed that metals are removed to low levels. This includes iron(II), the dominant metal ion in mine water, which is first oxidised to iron(III), whereafter it precipitates as Fe(OH)3 resulting in residual levels of Fe(II) in the mine water of less than 20 mg/ℓ. Sulphate is also removed to less than 25 mg/ℓ. The final sulphate concentration is a function of the amount of Ba(OH)2 dosed, as the amount of sulphate removed is stoichiometrically equivalent to the Ba(OH)2 dosage. During CO2-dosing, CaCO3 is precipitated to the saturation level of CaCO3.