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G Prado

Publications and source records attributed to G Prado.

10 recordsLinked to original sources
PubMed2001

In situ XAS study of LixNi0.7Fe0.15Co0.15O2 cathode material.

We have examined the oxidation states and local atomic structures of Ni, Fe, and Co in Li(x)Ni0.7Fe0.15Co0.15O2 as a function of Li content during the first charge in a Li/Li(x)Ni0.7Fe0.15Co0.15O2 nonaqueous cell. We show that the composition of the material in the pristine state is more accurately described by Li0.95Ni(II)0.09Ni(III)0.66Fe(III)0.15Co(III)0.25O2 Half of the Ni(II) resides in Li-vacant sites. Both Fe and Co substitute for Ni within the NiO2 slabs with no significant amounts of Fe or Co that can be attributed to Li-vacant sites. The local structure parameters are consistent with oxidation states observed on the basis of the XANES data. The Ni K-edge energy continuously shifts to a higher energy with decrease in Li content due to oxidation of Ni(II) to Ni(II) and Ni(III) to Ni(IV). After the complete oxidation of Ni(III) to Ni(IV), the Fe K-edge energy begins to increase with further decrease in Li content indicating the oxidation of Fe(III) to Fe(IV). The Co K-edge energy at half-height, on the other hand, is unchanged during the whole range of Li deintercalation indicating that no significant change in the oxidation state of Co occurs upon the complete removal of Li.

Journal Article↗
PubMed1999

Thermogravimetric study of thermal decontamination of soils polluted by hexachlorobenzene, 4-chlorobiphenyl, naphthalene, or n-decane.

To determine decontamination behavior as affected by temperature, shallow beds of a clay-rich, a calcerous, and a sedimentary soil, artificially polluted with hexachlorobenzene, 4-chlorobiphenyl, naphthalene, or n-decane, were separately heated at 5 degrees C min-1 in a thermogravimetric analyzer. Temperatures for deep cleaning of the calcerous and the sedimentary soil increased with increasing boiling point (bp) of the aromatic contaminants, but removal efficiencies still approached 100% well below the bp. Decontamination rates were therefore modelled according to a pollutant evaporation-diffusion transport model. For the calcerous and sedimentary soils, this model reasonably correlated removal of roughly the first 2/3 of the naphthalene, but gave only fair predictions for hexachlorobenzene and 4-chlorobiphenyl. It was necessary to heat the clay soil above the aromatics bp to achieve high decontamination efficiencies. Weight loss data imply that for temperatures from near ambient to as much as 150 degrees C, interactions of each aromatic with the clay soil, or its decomposition products, result in lower net volatilization of the contaminated vs. neat clay. A similar effect was observed in heating calcerous soil polluted with hexachlorobenzene from near ambient to about 140 degrees C. Decontamination mechanisms remain to be established, although the higher temperatures needed to remove aromatics from the clay may reflect a more prominent role for surface desorption than evaporation. This would be consistent with our estimates that the clay can accommodate all of the initial pollutant loadings within a single surface monolayer, whereas the calcerous and sedimentary soils cannot.

Alkanes↗
PubMed1999

Human articular chondrocyte adhesion and proliferation on synthetic biodegradable polymer films.

The effect of polymer chemistry on adhesion, proliferation, and morphology of human articular cartilage (HAC) chondrocytes was evaluated on synthetic degradable polymer films and tissue culture polystyrene (TCPS) as a control. Two-dimensional surfaces of poly(glycolide) (PGA), poly(L-lactide) (L-PLA), poly(D,L-lactide) (D,L-PLA), 85:15 poly(D,L-lactide-co-glycolide) (D,L-PLGA), poly(epsilon-caprolactone) (PCL), 90:10 (D,L-lactide-co-caprolactone) (D,L-PLCL), 9:91 D,L-PLCL, 40:60 L-PLCL, 67:33 poly(glycolide-co-trimethylene carbonate) (PGTMC), and poly(dioxanone) (PDO) were made by spin-casting into uniform thin films. Adhesion kinetics were studied using TCPS and PCL films and revealed that the rate of chondrocyte adhesion began to level off after 6 h. Degree of HAC chondrocyte adhesion was studied on all the substrates after 8 h, and ranged from 47 to 145% of the attachment found on TCPS. The greatest number of chondrocytes attached to PGA and 67:33 PGTMC polymer films, and attachment to PCL and L-PLA films was statistically lower than that found on PGA (p < 0.05). There was no correlation between amount of chondrocyte attachment to the substrates and the substrates' water contact angle. Chondrocytes proliferated equally well on all the substrates resulting in equivalent cell numbers on all the substrates at both day 4 and day 7 of the culture. However, these total cell numbers were reached as a result of a 88- and 42-fold expansion on PDO and PLA, respectively, which was significantly higher than the 11-fold expansion found on TCPS (p < 0.05). The greater fold expansion of the cells on PDO and L-PLA films may be attributed to the availability of space for cells to grow, since their numbers at the start of culture were fewer following the 8 h attachment period. This suggests that regardless of initial seeding density on these degradable polymer substrates (i.e., if some minimum number of cells are able to attach), they will eventually populate the surfaces of all these polymers given sufficient space and time.

Cartilage, Articular↗
PubMed1994

Functional and ligand binding specificity of the rabbit neutrophil IL-8 receptor.

IL-8 mediates migration and activation of neutrophils. This study describes the functional and ligand binding specificity of the human intercrine peptides IL-8, neutrophil-activating peptide 2 (NAP-2), melanoma growth stimulatory activity (GRO), and platelet factor 4 (PF4) to rabbit neutrophils and mammalian cell lines transfected with rabbit IL-8 receptor cDNA (F3R). Rabbit neutrophil membranes bound 125I-labeled IL-8 and 125I-labeled NAP-2 but did not bind 125I-labeled GRO or 125I-labeled PF4. Rabbit neutrophils mobilized intracellular Ca2+ in response to IL-8 and NAP-2 but not to GRO or PF4. Monkey kidney cells (COS-7) and hamster lung fibroblasts (CCL-39) were transiently and stably transfected with the rabbit neutrophil IL-8 receptor F3R cDNA. COS-7 cells transfected with F3R cDNA bound 125I-labeled IL-8 but did not bind other IL-8-related peptides such as 125I-labeled NAP-2, 125I-labeled GRO, or 125I-labeled PF4. Furthermore, bound 125I-labeled IL-8 was only displaced by unlabeled IL-8 but not by unlabeled NAP-2, GRO alpha, or PF4. Consistent with this observation, stably transfected CCL 39 cells expressing F3R cDNA mobilized Ca2+ only in response to IL-8. We conclude that F3R cDNA encodes a functional IL-8 receptor isotype with strict ligand binding specificity for IL-8, that rabbit neutrophils do not bind human GRO alpha, and it is suggested that rabbit neutrophils contain in addition to the F3R protein another IL-8 receptor isotype with broad ligand specificity or a distinct NAP-2 receptor.

Animals↗
PubMedDate not supplied

Natural occurrence of aflatoxins and zearalenone in maize in Brazil. Part II.

The levels of aflatoxins and zearalenone were determined in 328 samples of corn from the States of Santa Catarina, Minas Gerais, São Paulo, Paraná, Rio Grande do Sul and Espírito Santo by thin-layer chromatography; the samples were obtained from April 1985 through to March 1986. In 12.3% of these samples aflatoxin B1 was detected in concentrations that varied from 10 to 900 micrograms/kg (ppb); 18 samples showed levels above those tolerated by Brazilian legislation. Zearalenone was found in 4.5% of the samples analysed in concentrations that varied from 653 to 9830 micrograms/kg (ppb). The limit of detection of the method for the determination of zearalenone was 260 micrograms/kg (ppb) and the recovery was 100%.

Aflatoxin B1↗
PubMedDate not supplied

Chondromyxoid fibroma of the scapula associated with aneurysmal bone cyst.

A rare case of chondromyxoid fibroma of the scapula in a 21-year-old man is presented. This case is of interest because of its unusual site and association of aneurysmal bone cyst. Although chondromyxoid fibroma is uncommon bone tumor of the scapula, it should be considered in the differential diagnosis of expansile osteolytic lesion of the scapula.

Adult↗
PubMedDate not supplied

Determination of ochratoxin A in green coffee by immunoaffinity column cleanup and liquid chomatography: collaborative study.

A collaborative study was conducted to evaluate a method using immunoaffinity column cleanup with liquid chromatography (LC) for the determination of ochratoxin A (OTA) in green coffee at levels that could be included in possible future regulations of the European Union. The test portion was extracted with methanol-3% aqueous sodium hydrogen carbonate solution (50 + 50, v/v). The extract was filtered, and the filtrate was diluted with phosphate-buffered saline and applied to an immunoaffinity column containing antibodies specific for OTA. After washing, the toxin was eluted from the column with methanol and quantified by LC with fluorescence detection. Pairs of 4 homogeneous noncontaminated and naturally contaminated materials (mean levels of < 0.12, 2.44, 5.15, and 13.46 ng/g) and blank samples (< 0.12 ng/g) for spiking were sent to 20 participant laboratories from 8 countries. The materials were analyzed according to the method description and all difficulties encountered in the analysis were reported. Statistical analysis was carried out according to the Harmonized Protocol of the International Union of Pure and Applied Chemistry. The relative standard deviation for repeatability (RSDr) ranged from 7.42 to 20.94%, and the relative standard deviation for reproducibility (RSDR) ranged from 16.34 to 29.17%. The method showed acceptable within-laboratory and between-laboratories precision for green coffee materials, as evidenced by HorRat values of < or = 0.85, at the studied range, for spiked and naturally contaminated materials. The mean recovery was 92.8% for green coffee material spiked with OTA at a level of 4.82 ng/g.

Buffers↗
PubMedDate not supplied

[Infected atrial myxoma simulating infective endocarditis].

BACKGROUND: We present a case of infected atrial myxoma simulating bacterial endocarditis. MATERIAL AND METHODS: A 75 year old male, without any antecedents of interest, with fever an evolution a month, and a cardiac murmur. Blood cultures were practiced by BACTEC N.R. 730 system. The diagnosis was performed by the bidimensional and transesophageal echo, and confirmed with the resection from surgery. The method of bibliographical review used, has been the data base of comprehensive Medline, cvc since 1987 up June 1992 and the Oncodise's Concerlit archive from the year 1985 up to june 1992 the date base of the IME (Indice Médico Español) was also review up to April 1992. RESULTS: The blood cultures were positive, 7/7 Streptococcus viridans and 3/7 a Staphylococcus epidermidis resistant to meticiline, we them with the same antibiogram. Echocardiography and angiography show a lef atrial mass, surgical resection of the mass, confirmed the hystological diagnostic of the myxoma and signs of infection. CONCLUSIONS: This is the first case in our country, with shows the rarity of it. We analyze the differential diagnosis with the non infected myxoma and the bacterial endocarditis. We think that there should be an early surgical treatment, together with antibiotic therapy, due to the high incidence of embolism in theses patients.

Aged↗