Dredging and disposal of fine sediments in the state of Rio de Janeiro, Brazil.

Dredging is employed quite frequently in the state of Rio de Janeiro, especially for the installation and upkeep of commercial ports and rehabilitation of the hydraulic section of silted bodies of water. Until recently, all dredged material with no economic use was destined for marine disposal or stored at the edge of the water body. Since the 1990s, however, a new approach has been adopted for dredging as a result of pressure from the environmental organisations, encouraging closer interaction in Rio de Janeiro between the local and state public authorities and the universities on issues relating to licensing of this kind of activity. The recent experiments of the Civil and Ocean Engineering Programs of COPPE-UFRJ (Federal University of Rio de Janeiro) described herein are included in this context. The state of Rio de Janeiro has three bays, several coastal lagoon systems and a number of small and medium sized rivers in or close to urban areas, with a gentle slope as they near the sea. This is, then, a region highly susceptible to silting processes of water bodies, and therefore, to maintenance and/or environmental rehabilitation. As discussed in the article, fine and almost always organic sediments prevail, which is a considerable obstacle to the end disposal and possibility of reuse.     

Triethanolamine Stabilization of Methotrexate-β-Cyclodextrin Interactions in Ternary Complexes

The interaction of methotrexate (MTX) with beta-cyclodextrin (β-CD) in the presence of triethanolamine (TEA) was investigated with the aim to elucidate the mechanism whereby self-assembly cyclodextrin systems work in association with this third component. Solubility diagram studies showed synergic increment of the MTX solubility to be about thirty-fold. Experiments using 2D ROESY and molecular modeling studies revealed the inclusion of aromatic ring III of the drug into β-CD cavity, in which TEA contributes by intensifying MTX interaction with β-CD and stabilizes MTX:β-CD:TEA ternary complex by electrostatic interaction. The maintenance of these interactions in solid phase was also studied in ternary MTX:β-CD:TEA and comparisons were made with freeze dried binary MTX:β-CD and physical mixtures. FTIR studies evidenced that MTX–β-CD interaction remained in solid ternary complexes, which was also supported by thermal (differential scanning calorimetry (DSC), thermogravimetric analysis (TG)/first derivative of TG analysis (DTG) and C,N,H elementary analysis) and structural (X-ray diffraction analysis, (XRD)) studies, mainly regarding the increment of drug stability. The efficient in vitro drug dissolution studies successfully demonstrated the contribution of ternary complexes, which highlights the importance of this possible new raw material for further applications in drug delivery systems.     

Springtime Monitoring of Passive Cool Roofs in Subtropical Climate

Passive strategies for acclimatization of buildings have been studied by several authors in many countries, especially the evaporative and radiant cooling techniques. Fiber cement tiles are very common in popular constructions due to their low cost. However, they have over twice of the value thermal transmittance indicated to this bioclimatic zone according to Brazilian guidelines. The objective is to present an alternative to reduce high temperatures on fiber cement tiles. In this paper, the monitoring of passive cooling of roofing during the spring season in a city with subtropical climate is described. Single and combined reflective and evaporative cooling systems were studied in different environmental conditions. Internal surface temperatures of tiles were monitored together with weather variables. Results show a decrease of about 6 ℃, 9 ℃, 10 ℃ and 11 ℃ as compared to the original tiles according to environment conditions and the combined passive cooling techniques. These results allow for the conclusion that the use of passive cooling techniques opens up new possibilities to attenuate the internal surface temperatures of tiles and to consequently decrease the roofing solar heat gain into buildings, thus, providing less air cooling energy consumption.     

Fatigue crack growth rates of API X70 pipeline steel in a pressurized hydrogen gas environment

Hydrogen is known to have a deleterious effect on most engineering alloys. It has been shown repeatedly that the strength of steels is inversely related to the ductility of the material in hydrogen gas. However, the fatigue properties with respect to strength are not as well documented or understood. Here, we present the results of tests of the fatigue crack growth rate (FCGR) on API X70 from two sources. The two materials were tested in air, 5.5 and 34 MPa pressurized hydrogen gas, and at both 1 and 0.1 Hz. At these hydrogen pressures, the FCGR increases above that of air for all values of the stress intensity factor range (ΔK) greater than ~7 MPa · m^1/2. The effect of hydrogen is particularly sensitive at values of ΔK below ~15 MPa · m^1/2. That is, for values of ΔK between 7 and 15 MPa · m^1/2, the FCGR rapidly increases from approximately that found in air to as much as two orders of magnitude above that in air. Above 15 MPa · m^1/2, the FCGR remains approximately one to two orders of magnitude higher than that of air.     

Dilute mixed-acid pretreatment of sugarcane bagasse for ethanol production

Integral utilisation of bagasse is a high priority for the diversification of the sugarcane industry. The application of a biorefinery philosophy to bagasse utilisation requires its fractionation into its main components: cellulose, hemicelluloses and lignin. The first stage in that process is the pretreatment, in which a considerable part of hemicelluloses is solubilised, and cellulose is activated towards enzymatic hydrolysis. In this work, a pretreatment method using a mixture of sulfuric and acetic acid is investigated. Two different solid-to-liquid ratios (1.5:10 and 1:10) were used in the pretreatment. Both conditions efficiently hydrolysed the hemicelluloses giving removals above 90%. The extractive components were also effectively solubilised, and lignin was only slightly affected. Cellulose degradation was below 15%, which corresponded to the low crystallinity fraction. The analysis of the morphology of pretreated bagasse confirmed the results obtained in the chemical characterization.     

Modifications in the molecular structure of hydroxyapatite induced by titanium ions

The purpose of this study was to contribute to the understanding of the effect of titanium ions released from a metallic substrate on the molecular structure of hydroxyapatite. The effects of pH, time of incubation and concentration of titanium ions were investigated. The solids were analysed by X-ray diffraction, Fourier transform infrared spectroscopy, Fourier transform Raman spectroscopy, energy dispersive X-ray analysis and thermogravimetric analysis. The results clearly indicate the presence of a titanium phosphate, Ti(HPO₄)₂·nH₂O (n=1–3), which probably has a double layered structure. The formation of this compound is dependent on the titanium concentration and its crystallinity increases with the time of incubation.     

Treatment of lupus crisis with IgIV

BACKGROUND: Intravenous Immunoglobulin (i.v.Ig) has been advocated as efficacious for Systemic Lupus Erytematosus (SLE) and Lupic Nephritis (LN) using high dosages, propitious a prolonged remission of SLE. MATERIAL AND METHOD: We show the case of a male patient 16 years old, with SLE diagnosis until 1993, and LN phase IV. He attend to hospital with a Lupic Crisis, positives ANAs, DNAds, ScL 427, C3 45, C4 13, IgG 179, urinary sediment: leukocytes 30-40 xc, erythrocytes 8-10 xc. Renal failure: BUN 243, seric Cr: 10.16. I.v. Ig administrated 400 mgs k do. And nephrologic assistance, NK. RESULTS: There was improvement after infusion, clinical and serological, persisting with renal failure. The mechanism by which i.v. Ig might have effected improvement in this patient was reviewed. CONCLUSION: The use in our patient with SLE and LN was satisfactory. Is difficult affirm categorical the outcome or failure of i.v. Ig in patients with SLE, even report founded are only few cases report.     

Technology trends toward a system-in-a-module in power electronics

Currently, assemblies of power semiconductor switches and their associated drive circuitry are available in modules. From a few 100 watts downward, one finds silicon monolithic technology as the integration vehicle, while upward into the multi-kilowatt range, mixed mode module construction is used. This incorporates monolithic, hybrid, surface mount and wirebond technology. However, a close examination of the applications in motor drives and power supplies indicates that there has been no dramatic volume reduction of the subsystem. The power semiconductor modules have shrunk the power switching part of the converter, but the bulk of the subsystem volume still comprises the associated control, sensing, electromagnetic power passives and interconnect structures. The paper addresses the improvement of power processing technology through advanced integration of power electronics. The goal of a subsystem in a module necessitates this advanced integration. The central philosophy of this technology development research is to advance the state of the art by providing the concept of integrated power electronics modules (IPEMs). The technology underpinning such an IPEM approach is discussed. The fundamental functions in electronic power processing, the materials, processes and integration approaches and future concepts are explained.     

Serum bile acids and ursodeoxycholic acid treatment in cystic fibrosis-related liver disease

Increased circulating levels of hepatotoxic bile acids may contribute to the cholestasis characteristic of cystic fibrosis-related liver disease. The aims of this study were to compare serum bile acid profiles in patients with cystic fibrosis with and without liver disease, and to evaluate the effect of treatment with ursodeoxycholic acid, a non-hepatotoxic bile acid, on liver biochemistry and serum bile acids in patients with cystic fibrosis-related liver disease. Fasting and postprandial serum bile acid levels were analysed in 15 patients (nine males; median age 18 years) with cystic fibrosis-related liver disease and compared with serum bile acid levels in 18 cystic fibrosis patients (12 males; median age 22 years) without liver disease and 10 control subjects. Fasting and postprandial serum levels of primary and secondary serum bile acids were analysed using high-performance liquid chromatography. Liver biochemistry and serum bile acids were measured in six cystic fibrosis patients with liver disease before and 6 months after treatment with ursodeoxycholic acid 20 mg/kg/day and compared with six control patients with cystic fibrosis-related liver disease. Total fasting and postprandial serum bile acid levels were significantly (P < 0.01) elevated in patients with liver disease compared to those without liver disease and controls. The fasting glycine conjugates of cholic acid, chenodeoxycholic acid and deoxycholic acid, and the fasting and postprandial taurine conjugates of cholic acid and chenodeoxycholic acid were significantly (P < 0.05) elevated in liver disease patients compared to patients without liver disease and controls. After 6 months' treatment with ursodeoxycholic acid, although the serum was significantly saturated with ursodeoxycholic acid and significant improvements in liver biochemistry were observed in the treatment group, there was no significant reduction in the levels of individual serum bile acids. Although circulating levels of potentially hepatotoxic serum bile acids are elevated in patients with cystic fibrosis-related liver disease, improvements in liver biochemistry associated with ursodeoxycholic acid treatment cannot be attributed solely to alterations in levels of endogenous bile acids.     

A three-level converter and its applicationto power factor correction

The first part of this paper introduces a novel three-level dc-dc converter topology. It is shown that a floating capacitor connected across the clamping diodes of a conventional three-level converter enables phase-shift control while retaining zero voltage switching. Design constraints and experimental results are shown for a 6-kW, 100-kHz dc-dc prototype. The second part of the paper discusses the same three-level topology operated as a single-stage front-end converter. In this application, the converter realizes power factor correction and dc output voltage regulation. To ensure low harmonic distortion, the input currents are operated in discontinuous conduction mode, and the performance, including soft switching, is also verified on a 3-kW, 50-kHz ac-dc converter.