Erratum: Development of composites based on recycled polyethylene/sugarcane bagasse fibers

When this article was first published in Polymer Composites, 35:768–774, 2014; DOI: 10.1002/pc.22720 , the lead authors name was incorrectly supplied to the Publisher. His correct name appears above. The authors apologize for any inconvenience this may have caused.     

In vitro skin permeation and retention of paromomycin from liposomes for topical treatment of the cutaneous leishmaniasis

Paromomycin (PA), a very hydrophilic antibiotic, has been tested as an alternative topical treatment against cutaneous leishmaniasis (CL). Although this treatment has shown promising results, it has not been successful in accelerating the recovery in most cases. This could be attributed to the low skin penetration of PA. Liposomal formulations usually provide sustained and enhanced drug levels in skin. The aim of this study was to prepare liposomal formulations containing PA and to investigate their potential as topical delivery systems of this antileishmanial. Large multilamellar vesicles (MLVs) were prepared by conventional solvent evaporation method. Large unilamellar vesicles (LUVs) were prepared by reverse-phase evaporation method. The lipids used were soybean phosphatidylcholine (PC) and PC:cholesterol (CH) (molar ratio 1:1). The skin permeation experiments across stripped and normal hairless mice skin were performed in modified Franz diffusion cells. The PA entrapment in LUV liposomes (20.4 ± 2.2%) was higher than that observed for MLV liposomes (7.5 ± 0.9%). Drug entrapment was 41.9 ± 6.2% and 27.2 ± 2.4% for PC and PC:CH LUV, respectively. The skin permeation was 1.55 ± 0.31%, 1.29 ± 0.40%, 0.20 ± 0.08%, and 0.50 ± 0.19% for PC LUV, PC:CH LUV, empty LUV + PA and aqueous solution, respectively. Controlled topical delivery, across stripped skin, was observed for PA entrapped in LUV liposomes.     

Investigation of water electrolysis by spectral analysis. I. Influence of the current density

The potential (or current) fluctuations observed under current (or potential) control during gas evolution were analysed by spectral analysis. The power spectral densities (psd) of these fluctuations were measured for hydrogen and oxygen evolution in acid and alkaline solutions at a platinum disk electrode of small diameter. Using a theoretical model, some parameters of the gas evolution were derived from the measured psd of the potential fluctuations, such as the average number of detached bubbles per time unit, the average radius of the detached bubbles and the gas evolution efficiency. The influence of the electrolysis current on these parameters was also investigated. The results of this first attempt at parameter derivation are discussed.Nomenclature b Tafel coefficient (V^–1), Equation 46 - C electrode double layer capacity (F) - e gas evolution efficiency (%) - f frequency (Hz) - f _p frequency of the peak in the psd _v and _i (Hz) - F Faraday constant, 96 487 C mol^–1 - l electrolysis current (A) - J electrolysis current density (mA cm^–2) - k slope of the linear potential increase (V s^–1), see Fig. 1 - n number of electrons involved in the reaction to form one molecule of the dissolved gas - r _b radius of a spherical glass ball (m) - r _e radius of the disk electrode (m) - R _e electrolyte resistance () - R _p polarization resistance () - R _t charge transfer resistance () - u ₁ distribution function of the time intervals between two successive bubble departures (s^–1) - v _g mean volume of gas evolved per unit time (m³ s^–1) - v _t gas equivalent volume produced in molecular form per unit time (m³ s^–1) - V ₀ gas molar volume, 24.5×10^–3 m³ at 298 K - x ₀ time pseudoperiod of bubbles evolution (s) - Z electrode electrochemical impedance () Greek characters _e dimensionless proportional factor (Equation 19) - slope of log /logJ and loge/logJ curves - number of bubbles evolved per unit time (s^–1) - _a activation overpotential (V) - _ci concentration overpotential of reacting ionic species (V) - _cs concentration overpotential of dissolved molecular gas (V) - _ohm ohmic overpotential (V) - _t total overpotential (V) - v parameter characteristic of the gas evolution pseudoperiodicity, Equation 13 (s^–1) - time constant of the double layer capacity change (s) - _v power spectral density (psd) of the potential fluctuations (V² Hz^–1) - _i power spectral density (psd) of the current fluctuations (A² Hz^–1) Special symbols spatial average of the overpotential _j over the electrode surface - time averaged value of - _j fluctuation of around - <> mean value of the total overpotential jump amplitude due to a bubble departure - <I> mean value of the current jump amplitude due to a bubble departure Paper presented at the 2nd International Symposium on Electrolytic Bubbles organized jointly by the Electrochemical Technology Group of the Society of Chemical Industry and the Electrochemistry Group of the Royal Society of Chemistry and held at Imperial College, London, 31st May and 1st June 1988.     

Evaluation of ion exchange resins for recovery of metals from electroplating sludge

In the present study, the recovery of metal ions from industrial solid residues from a galvanoplasty industry (Rio de Janeiro, Brazil) was investigated by cationic and anionic ion exchange resins. The electroplating residues were composed of the metals Cu²⁺, Fe³⁺, Al³⁺, Ni²⁺, and Cr³⁺. The studies of sorption were conducted under batch and column conditions. Based on these studies, the sorption parameters and the breakthrough curves for both resins were determined. Studies of the sorption equilibrium and kinetics were also performed. The maximum sorption capacities q _e (mg g^?1) of the cationic resin were: Cu²⁺: 1.9, Fe³⁺: 0.6 and Al³⁺: 0.4. For the anionic resin, the maxim values of q _e were Cu²⁺: 0.4 and Fe³⁺: 0.1. The Freundlich model was more adequate to describe the ion exchange equilibrium and the sorption mechanism fit the pseudo second-order kinetic model for both resins. The breakpoint of Cu²⁺ (100 ppm) occurred after passing 1,860 and 2,220 cm³ of residue solution through 20.0 g of the resins (column with h:6.0 cm and d:4.3 cm, flow rate: 60 cm³ min^?1). The column regeneration was carried out for five sorption–desorption cycles using H₂SO₄ 2.4 mol L^?1 (cationic) and HCl 2.0 mol L^?1 (anionic).     

A Novel Direct Method for Determination of Riboflavin in Alcoholic Fermented Beverages

A novel cheap and user friendly method for the determination of riboflavin in wine and beer samples has been developed based on the fluorescence quenching effect given by riboflavin binding to the chicken egg white, riboflavin-binding protein. The method is based on the use of a single diode fluorimeter with emission within riboflavin absorption profile. Linearity was observed over riboflavin concentration from 0 to 500 ng/mL with a limit of detection of 15 ng/mL. Data on real wine and beer samples were obtained and compared with classical high-performance liquid chromatography (HPLC)-based method. The fluorimetric method thus appears much faster and cheaper than the chromatographic one and easily amenable to routine analysis in beverage industry.     

Amino-functionalized carbon nanotubes for effectively improving the mechanical properties of pre-impregnated epoxy resin/carbon fiber

Pre-impregnated carbon fiber/epoxy resin (CF/epoxy prepreg) gained its popularity for significant stress applications, especially in the aerospace industry, owing to its excellent resistance and low specific mass. However, these CF/epoxy prepregs have a tendency to crack propagation. A solution for the prepregs fragility is the addition of carbon nanotubes (CNTs), especially those functionalized with amino groups, reinforcing the material due to its exceptional mechanical properties. In this work, the influence of the carbon chain length of two different amino-functionalized CNTs from diverse backgrounds (commercial and laboratory growth CNTs) is studied. The nanofillers were added in CF/epoxy prepregs by dry spraying without solvent aid. CNTs' samples were characterized by X-ray photoelectron spectroscopy, Raman spectroscopy, transmission electron microscopy, and thermogravimetric analysis (TGA), while the composites were analyzed by TGA, dynamic-mechanical analysis, and field emission scanning electron microscopy. The various surface treatment occurred at different levels according to the CNTs background, and all samples exhibited a distinct behavior. These differences were also observed in the composites' thermomechanical performance: CNTs functionalized with larger carbon chain amine presented the best results, with an increase of almost 100% in the storage moduli (E'), confirming the efficiency of amino-functionalized CNTs in the reinforcement of CF/epoxy prepregs.     

Detoxification of Ciprofloxacin in an Anaerobic Bioprocess Supplemented with Magnetic Carbon Nanotubes: Contribution of Adsorption and Biodegradation Mechanisms

In anaerobic bioreactors, the electrons produced during the oxidation of organic matter can potentially be used for the biological reduction of pharmaceuticals in wastewaters. Common electron transfer limitations benefit from the acceleration of reactions through utilization of redox mediators (RM). This work explores the potential of carbon nanomaterials (CNM) as RM on the anaerobic removal of ciprofloxacin (CIP). Pristine and tailored carbon nanotubes (CNT) were first tested for chemical reduction of CIP, and pristine CNT was found as the best material, so it was further utilized in biological anaerobic assays with anaerobic granular sludge (GS). In addition, magnetic CNT were prepared and also tested in biological assays, as they are easier to be recovered and reused. In biological tests with CNM, approximately 99% CIP removal was achieved, and the reaction rates increased ≈1.5-fold relatively to the control without CNM. In these experiments, CIP adsorption onto GS and CNM was above 90%. Despite, after applying three successive cycles of CIP addition, the catalytic properties of magnetic CNT were maintained while adsorption decreased to 29 ± 3.2%, as the result of CNM overload by CIP. The results suggest the combined occurrence of different mechanisms for CIP removal: adsorption on GS and/or CNM, and biological reduction or oxidation, which can be accelerated by the presence of CNM. After biological treatment with CNM, toxicity towards Vibrio fischeri was evaluated, resulting in ≈ 46% detoxification of CIP solution, showing the advantages of combining biological treatment with CNM for CIP removal.     

Rheological behavior and stability of emulsions obtained from Pereskia aculeata Miller via different drying methods

Hydrocolloid powders from Pereskia aculeata Miller were obtained by using drying in a vacuum oven and freeze-drying at different concentrations (0.5–3.0 g of hydrocolloids/100 g of aqueous phase) to produce oil-in-water emulsions. The rheological characteristics of the emulsions and their microstructures were determined. The freeze-dried hydrocolloids and higher hydrocolloid concentrations resulted in emulsions with higher viscosities. The drying method and hydrocolloid concentration influenced the thixotropic behavior, and the resulting emulsions exhibited shear-thinning behavior. Microstructural analysis showed that with increasing freeze-dried hydrocolloid concentration, the emulsions had droplets with lower average diameters and greater uniformity, suggesting greater system stability.     

A proxy for estimating the cell volume of Ceratium furcoides (Dinophyceae): basis for monitoring Brazilian reservoirs

Ceratium furcoides, a large bloom‐forming dinoflagellate, is considered an invasive species in South American freshwater systems. As it can cause ecological and economic problems, particularly in reservoirs, this issue has been discussed among researchers and companies responsible for monitoring Brazilian aquatic systems. To this end, although biovolume estimates are an important tool for ecological studies, calculating biovolumes is a cumbersome procedure, requiring a large number of samples and measurements. This study was undertaken to provide a simple measured morphological trait as a proxy for the cell volume of C. furcoides in Brazilian water systems that have been invaded by these organisms, exhibiting dense, recurrent blooms. Morphometric data were obtained monthly from two subtropical reservoirs in southern Brazil with public supply purposes. Cell volumes exhibited seasonal variations, with significant differences by months and seasons, although not between reservoirs or morphotypes with two or three antapical horns, meaning biovolume estimates must consider seasonal variations in dinoflagellate size. Body width was significantly correlated with 11 other measured dimensions of the cell and was highly correlated with cell volume, thereby being the most representative measure of cell volume. Linear regressions for estimating cell volumes from cell body width revealed a strong positive trend when both full sampling and seasonally grouped samples were considered. Morphometric data of C. furcoides invasions in other Brazilian subtropical and tropical waterbodies also were used, exhibiting significant correlation with the formula proposed in this study.