Nitric Oxide-releasing Poly(vinyl Alcohol) Film For Increasing Dermal Vasodilation.

Pathological conditions associated with the impairment of nitric oxide (NO) production in the vasculature, such as Raynaud's syndrome and diabetic angiopathy, have stimulated the development of new biomaterials capable of delivering NO topically. With this purpose, we modified poly(vinyl-alcohol) (PVA) by chemically crosslinking it via esterification with mercaptosuccinic acid. This reaction allowed the casting of sulfhydrylated PVA (PVA-SH) films. Differential scanning calorimetry and X-ray diffractometry showed that the crosslinking reaction completely suppressed the crystallization of PVA, leading to a non-porous film with a homogeneous distribution of -SH groups. The remaining free hydroxyl groups in the PVA-SH network conferred partial hydrophylicity to the material, which was responsible for a swelling degree of ca. 110%. The PVA-SH films were subjected to an S-nitrosation reaction of the -SH groups, yielding a PVA containing S-nitrosothiol groups (PVA-SNO). Amperometric and chemiluminescence measurements showed that the PVA-SNO films were capable of releasing NO spontaneously after immersion in physiological medium. Laser Doppler-flowmetry, used to assess the blood flow in the dermal microcirculation, showed that the topical application of hydrated PVA-SNO films on the health skin led to a dose- and time-dependent increase of more than 5-fold in the dermal baseline blood flow in less than 10min, with a prolonged action of more than 4h during continuous application. These results show that PVA-SNO films might emerge as a new material with potential for the topical treatment of microvascular skin disorders.

Qualidade pós-colheita de caqui 'fuyu' com utilização de diferentes concentrações de cobertura comestível

One of the main objectives of applying edible coatings on fruits surface is to create a protective film to reduce weight loss due to evaporation and transpiration and also to decrease the risk of fruit rot caused by environmental contamination, in order to improve the visual aspect. Therefore, it is possible to increase shelf life, and decrease post harvest losses. Persimmon is a much appreciated fruit, with high potential for export, but sensitive to handling and storage. This study aimed to evaluate the effect of applying the edible coating Megh Wax ECF-124 (18% of active composts, consisting of emulsion of carnauba wax, anionic surfactant, preservative and water) produced by Megh Industry and Commerce Ltda in three different concentrations (25, 50 and 100%) on post harvest quality of 'Fuyu' persimmon stored for 14 days. The attributes evaluated for quality were: firmness, pH, acidity, soluble solids, weight loss and color. The results showed that application of carnauba wax in different concentrations was effective on decreasing weight loss of persimmon cv. Fuyu and maintenance of color aspects. Treatment at lower concentration, 25%, showed lower rate of discharge, but high concentrations showed lower values of mass loss. Carnauba wax application showed a high potential for use on postharvest conservation, and can be applied together with other technologies, helping to maintain quality for export.

A biosensor based on immobilization of lactate oxidase in a PB-CTAB film for FIA determination of lactate in beer samples

An amperometric lactate biosensor with lactate oxidase immobilized into a Prussian Blue (PB) modified electrode was fabricated. The advantage of using cetyltrimethylammonium bromide (CTAB) in the electrodeposition step of PB films onto glassy carbon surfaces was confirmed taking into account both the stability and sensitivity of the measurements. The biosensor was used in the development of a FIA amperometric method for the determination of lactate. Under optimal operating conditions (pH = 6.9, E = -0.1 V), the linear response of the method was extended up to 0.28 µmol L-1 lactate with a limit of detection of 0.84 mmol L-1. The repeatability of the method for injections of a 0.28 mmol L-1 lactate solution was 2.2 % (n = 18). The usefulness of the method was demonstrated by determining lactate in beer samples and the results were in good agreement with those obtained by using a reference spectrophotometric enzyme method.

Influence of film thickness on the crystallization of Ni-doped amorphous silicon samples

This work reports on the crystallization of amorphous silicon (a-Si) films doped with 1 at. % of nickel. The films, with thicknesses ranging from 10 to 3000 nm, were deposited using the cosputtering method onto crystalline quartz substrates. In order to investigate the crystallization mechanism in detail, a series of undoped a-Si films prepared under the same deposition conditions were also studied. After deposition, all a-Si films were submitted to isochronal thermal annealing treatments up to 1000 degrees C and analyzed by Raman scattering spectroscopy. Based on the present experimental results, it is possible to state that (a) when compared to the undoped a-Si films, those containing 1 at. % of Ni crystallize at temperatures similar to 100 degrees C lower, and that (b) the film thickness influences the temperature of crystallization that, in principle, tends to be lower in films thinner than 1000 nm. The possible reasons associated to these experimental observations are presented and discussed in view of some experimental and thermodynamic aspects involved in the formation of ordered Si-Si bonds and in the development of Ni-silicide phases. (c) 2008 American Institute of Physics.

Studies on the Electrocatalytic Reduction of Hydrogen Peroxide on a Glassy Carbon Electrode Modified With a Ruthenium Oxide Hexacyanoferrate Film

The electrocatalytic reduction of hydrogen peroxide on a glassy carbon (GC) electrode modified with a ruthenium oxide hexacyanoferrate (RuOHCF) was investigated using rotating disc electrode (RDE) voltammetry aiming to improve the performance of the sensor for hydrogen peroxide detection. The influence of parameters such as rotation speed, film thickness and hydrogen peroxide concentration indicated that the rate of the cross-chemical reaction between Ru(II) centres immobilized into the film and hydrogen peroxide controls the overall process. The kinetic regime could be classified as LSk mechanism, according to the diagnostic table proposed by Albery and Hillman, and the kinetic constant of the mediated process was found to be 706 mol(-1) cm(3) s(-1). In the LSk case the reaction layer is located at a finite layer close to the modifier layer/solution interface

Polymer matrix sensitizing effect on photoluminescence properties of Eu(3+)-beta-diketonate complex doped into poly-beta-hydroxybutyrate (PHB) in film form

In this work is reported the sensitization effect by polymer matrices on the photoluminescence properties of diaquatris(thenoyltrifluoroacetonate)europium(III), [Eu(tta)(3)(H(2)O)(2)], doped into poly-beta-hydroxybutyrate (PHB) with doping percentage at 1, 3, 5, 7 and 10% (mass) in film form. TGA results indicated that the Eu(3+) complex precursor was immobilized in the polymer matrix by the interaction between the Eu(3+) complex and the oxygen atoms of the PHB polymer when the rare earth complex was incorporated in the polymeric host. The thermal behaviour of these luminescent systems is similar to that of the undoped polymer, however, the T(onset) temperature of decomposition decreases with increase of the complex doping concentration. The emission spectra of the Eu(3+) complex doped PHB films recorded at 298 K exhibited the five characteristic bands arising from the (5)D(0) -> (7)F(J) intraconfigurational transitions (J = 0-4). The fact that the quantum efficiencies eta of the doped film increased significantly revealed that the polymer matrix acts as an efficient co-sensitizer for Eu(3+) luminescent centres and therefore enhances the quantum efficiency of the emitter (5)D(0) level. The luminescence intensity decreases, however, with increasing precursor concentration in the doped polymer to greater than 5% where a saturation effect is observed at this specific doping percentage, indicating that changes in the polymeric matrix improve the absorption property of the film, consequently quenching the luminescent effect.

Combined photocatalytic and fungal processes for the treatment of nitrocellulose industry wastewater

The objective of this work was to characterize the delignification effluent originating from the delignification industry and evaluate the combination of the fungus and photocatalytic process (TiO(2)/UV system) for the treatment of this effluent. The delignification effluent has proven harmful to the environment because it presents high color (3516 CU), total phenol (876 mg/L and TOC (1599 mg/L) and is also highly toxic even in a low concentration. The results of photocatalysis were 11%, 25% and 13% higher for reductions in color, total phenol and TOC, respectively. The combined treatments presented benefits when compared to the non-combined treatments. Fungus and photocatalysis in combination proved to be the best treatment, reducing the color, total phenol, toxicity (inhibition of Escherichia coli growth) and TOC by 94.2%, 92.6%, 4.9% and 62%, respectively. (C) 2008 Elsevier B.V. All rights reserved.

High Solids Content, Soap-Free, Film-Forming Latexes Stabilized by Laponite Clay Platelets

High solids content film-forming poly[styrene-co-(n-butyl acrylate)] [poly(Sty-co-BuA)] latexes armored with Laponite clay platelets have been synthesized by soap-free emulsion copolymerization of styrene and n-butyl acrylate. The polymerizations were performed in batch in the presence of Laponite and a methyl ether acrylateterminated poly(ethylene glycol) macromonomer in order to promote polymer/clay association. The overall polymerization kinetics showed a pronounced effect of clay on nucleation and stabilization of the latex particles. Cryo-transmission electron microscopy observation confirmed the armored morphology and indicated that the majority of Laponite platelets were located at the particle surface. The resulting nanostructured films displayed enhanced mechanical properties.

Sensorless synchronization method for thin-film direct optical broadband monitoring system

Optical monitoring systems are necessary to manufacture multilayer thin-film optical filters with low tolerance on spectrum specification. Furthermore, to have better accuracy on the measurement of film thickness, direct monitoring is a must. Direct monitoring implies acquiring spectrum data from the optical component undergoing the film deposition itself, in real time. In making film depositions on surfaces of optical components, the high vacuum evaporator chamber is the most popular equipment. Inside the evaporator, at the top of the chamber, there is a metallic support with several holes where the optical components are assembled. This metallic support has rotary motion to promote film homogenization. To acquire a measurement of the spectrum of the film in deposition, it is necessary to pass a light beam through a glass witness undergoing the film deposition process, and collect a sample of the light beam using a spectrometer. As both the light beam and the light collector are stationary, a synchronization system is required to identify the moment at which the optical component passes through the light beam.

Film thickness measurement techniques applied to micro-scale two-phase flow systems

Recently semi-empirical models to estimate flow boiling heat transfer coefficient, saturated CHF and pressure drop in micro-scale channels have been proposed. Most of the models were developed based on elongated bubbles and annular flows in the view of the fact that these flow patterns are predominant in smaller channels. In these models, the liquid film thickness plays an important role and such a fact emphasizes that the accurate measurement of the liquid film thickness is a key point to validate them. On the other hand, several techniques have been successfully applied to measure liquid film thicknesses during condensation and evaporation under macro-scale conditions. However, although this subject has been targeted by several leading laboratories around the world, it seems that there is no conclusive result describing a successful technique capable of measuring dynamic liquid film thickness during evaporation inside micro-scale round channels. This work presents a comprehensive literature review of the methods used to measure liquid film thickness in macro- and micro-scale systems. The methods are described and the main difficulties related to their use in micro-scale systems are identified. Based on this discussion, the most promising methods to measure dynamic liquid film thickness in micro-scale channels are identified. (C) 2009 Elsevier Inc. All rights reserved.

AnSBBR Applied to a Personal Care Industry Wastewater Treatment: Effects of Fill Time, Volume Treated Per Cycle, and Organic Load

A study was performed regarding the effect of the relation between fill time, volume treated per cycle, and influent concentration at different applied organic loadings on the stability and efficiency of an anaerobic sequencing batch reactor containing immobilized biomass on polyurethane foam with recirculation of the liquid phase (AnSBBR) applied to the treatment of wastewater from a personal care industry. Total cycle length of the reactor was 8 h (480 min). Fill times were 10 min in the batch operation, 4 h in the fed-batch operation, and a 10-min batch followed by a 4-h fed batch in the mixed operation. Settling time was not necessary since the biomass was immobilized and decant time was 10 min. Volume of liquid medium in the reactor was 2.5 L, whereas volume treated per cycle ranged from 0.88 to 2.5 L in accordance with fill time. Influent concentration varied from 300 to 1,425 mg COD/L, resulting in an applied volumetric organic load of 0.9 and 1.5 g COD/L.d. Recirculation flow rate was 20 L/h, and the reactor was maintained at 30 A degrees C. Values of organic matter removal efficiency of filtered effluent samples were below 71% in the batch operations and above 74% in the operations of fed batch followed by batch. Feeding wastewater during part of the operational cycle was beneficial to the system, as it resulted in indirect control over the conversion of substrate into intermediates that would negatively interfere with the biochemical reactions regarding the degradation of organic matter. As a result, the average substrate consumption increased, leading to higher organic removal efficiencies in the fed-batch operations.

Anaerobic sequencing batch biofilm reactor applied to automobile industry wastewater treatment: Volumetric loading rate and feed strategy effects

This paper presents a technological viability study of wastewater treatment in an automobile industry by an anaerobic sequencing batch biofilm reactor containing immobilized biomass (AnSBBR) with a draft tube. The reactor was operated in 8-h cycles, with agitation of 400 rpm, at 30 degrees C and treating 2.0 L wastewater per cycle. Initially the efficiency and stability of the reactor were studied when supplied with nutrients and alkalinity. Removal efficiency of 88% was obtained at volumetric loading rate (VLR) of 3.09 mg COD/L day. When VLR was increased to 6.19 mg COD/L day the system presented stable operation with reduction in efficiency of 71%. In a second stage the AnSBBR was operated treating wastewater in natura, i.e., without nutrients supplementation, only with alkalinity, thereby changing feed strategy. The first strategy consisted in feeding 2.0 L batch wise (10 min), the second in feeding 1.0 L of influent batch wise (10 min) and an additional 1.0 L fed-batch wise (4 h), both dewatering 2.0 L of the effluent in 10 min. The third one maintained 1.0 L of treated effluent in the reactor, without discharging, and 1.0 L of influent was fed fed-batch wise (4 h) with dewatering 1.0 L of the effluent in 10 min. For all implemented strategies (VLR of 1.40, 2.57 and 2.61 mg COD/L day) the system presented stability and removal efficiency of approximately 80%. These results show that the AnSBBR presents operational flexibility, as the influent can be fed according to industry availability. In industrial processes this is a considerable advantage, as the influent may be prone to variations. Moreover, for all the investigated conditions the kinetic parameters were obtained from fitting a first-order model to the profiles of organic matter, total volatile acids and methane concentrations. Analysis of the kinetic parameters showed that the best strategy is feeding 1.0 L of influent batchwise (10 min) and 1.0 L fed-batch wise (4 h) in 8-h cycle. (c) 2007 Elsevier B.V. All rights reserved.

Coloured Petri nets and graphical simulation for the validation of a robotic cell in aircraft industry

This paper proposes a mixed validation approach based on coloured Petri nets and 3D graphic simulation for the design of supervisory systems in manufacturing cells with multiple robots. The coloured Petri net is used to model the cell behaviour at a high level of abstraction. It models the activities of each cell component and its coordination by a supervisory system. The graphical simulation is used to analyse and validate the cell behaviour in a 3D environment, allowing the detection of collisions and the calculation of process times. The motivation for this work comes from the aeronautic industry. The automation of a fuselage assembly process requires the integration of robots with other cell components such as metrological or vision systems. In this cell, the robot trajectories are defined by the supervisory system and results from the coordination of the cell components. The paper presents the application of the approach for an aircraft assembly cell under integration in Brazil. This case study shows the feasibility of the approach and supports the discussion of its main advantages and limits. (C) 2011 Elsevier Ltd. All rights reserved.

Toxicity-directed approach of polyester manufacturing industry wastewater provides useful information for conducting treatability studies

A broader characterization of industrial wastewaters, especially in respect to hazardous compounds and their potential toxicity, is often necessary in order to determine the best practical treatment (or pretreatment) technology available to reduce the discharge of harmful pollutants to the environment or publicly owned treatment works. Using a toxicity-directed approach, this paper sets the base for a rational treatability study of polyester resin manufacturing. Relevant physical and chemical characteristics were determined. Respirometry was used for toxicity reduction evaluation after physical and chemical effluent fractionation. Of all the procedures investigated, only air stripping was significantly effective in reducing wastewater toxicity. Air stripping in pH 7 reduced toxicity in 18.2%, while in pH 11 a toxicity reduction of 62.5% was observed. Results indicated that toxicants responsible for the most significant fraction of the effluent`s instantaneous toxic effect to unadapted activated sludge were organic compounds poorly or not volatilized in acid conditions. These results led to useful directions for conducting treatability studies which will be grounded on actual effluent properties rather than empirical or based on the rare specific data on this kind of industrial wastewater. (C) 2008 Elsevier B.V. All rights reserved.

New reconciliation model for gold industry

Reconciliation can be divided into stages, each stage representing the performance of a mining operation, such as: long-term estimation, short-term estimation, planning, mining and mineral processing. The gold industry includes another stage which is the budget, when the company informs the financial market of its annual production forecast. The division of reconciliation into stages increases the reliability of the annual budget informed by the mining companies, while also detecting and correcting the critical steps responsible for the overall estimation error by the optimization of sampling protocols and equipment. This paper develops and validates a new reconciliation model for the gold industry, which is based on correct sampling practices and the subdivision of reconciliation into stages, aiming for better grade estimates and more efficient control of the mining industry`s processes, from resource estimation to final production.