Measurement of the anodic potential in solid state: A tool for determination of the antioxidant potential of phytomedicine

The electroanalytical techniques are very promissing to perform the quality control of crude vegetable. Solid State Differential Pulse Voltammetry in the supporting electrolyte is able to detect the oxidation signals of the active material, which can be used as a parameter to identify the type of crude vegetable and its antioxidant activity. The working electrode consisted in a carbon paste electrode modified with the powder of vegetable raw material (EMF). The electrochemical measurements were performed in a cell containing the working (EMF), reference (Ag/AgCl, KClsat) and auxiliary (Pt) electrodes.

Coating of Cotton Yarn with Poly(vinyl alcohol) and Poly(N-vinyl-2-pyrrolidone) Crosslinked via Ultraviolet Radiation

The coating of cotton fiber is used in the textile industry to increase the mechanical resistance of the yarn and their resistance to vibration, friction, impact, and elongation, which are some of the forces to which the yarn is subjected during the weaving process. The main objective of this study was to investigate the use of synthetic hydrophilic polymers, poly(vinyl alcohol) (PVA), and poly(N-vinyl-2-pyrrolidone) (PVP) to coat 100% cotton textile fiber, with the aim of giving the fiber temporary mechanical resistance. For the fixation of the polymer on the fiber, UV-C radiation was used as the crosslinking process. The influence of the crosslinking process was determined through tensile testing of the coated fibers. The results indicated that UV-C radiation increased the mechanical resistance of the yarn coated with PVP by up to 44% and the yarn coated with PVA by up to 67% compared with the pure cotton yarn, that is, without polymeric coating and crosslinking. This study is of great relevance, and it is important to consider that UV-C radiation dispenses with the use of chemical substances and prevents the generation of toxic waste at the end of the process. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 2560-2567, 2011

Crosslinking of Poly(N-vinyl-2-pyrrolidone) in the Coating of Cotton Yarn

Coating of cotton yarn is employed in the textile industry to increase the mechanical resistance of the yarns and resistance to vibration, friction, impact, and elongation, which are some of the forces to which the yarn is subjected during the weaving process. The main objective of this study is to investigate the usage of a synthetic hydrophilic polymer, poly(N-vinyl-2-pyrrolidone) (PVP), to coat 100% cotton textile yarn, aiming to give the yarn a temporary mechanical resistance. For the improvement of the mechanical resistance of the yarn, the following crosslinking processes of PVP were investigated: UV-C (ultraviolet) radiation, the Fenton and photo-Fenton reactions, and sensitized UV-C radiation. The influence of each crosslinking process was determined through tensile testing of the coated yarns. The results indicated that the best crosslinking process employed was UV-C radiation; increasing the mechanical resistance of the yarn up to 44% if compared with the pure cotton yarn, that is, without polymeric coating and crosslinking. POLYM. ENG. SCI., 51:445-453, 2011. (C) 2010 Society of Plastics Engineers

Photocatalytic degradation of methylene blue by TiO(2)-Cu thin films: Theoretical and experimental study

In this work the effect of doping concentration and depth profile of Cu atoms on the photocatalytic and surface properties of TiO(2) films were studied. TiO(2) films of about 200 nn thickness were deposited on glass substrates on which a thin Cu layer (5 nm) was deposited. The films were annealed during 1 s to 100 degrees C and 400 degrees C, followed by chemical etching of the Cu film. The grazing incidence X-ray fluorescence measurements showed a thermal induced migration of Cu atoms to depths between 7 and 31 nm. The X-ray photoelectron spectroscopy analysis detected the presence of TiO(2), Cu(2)O and Cu(0) phases and an increasing Cu content with the annealing temperature. The change of the surface properties was monitored by the increasing red-shift and absorption of the ultraviolet-visible spectra. Contact angle measurements revealed the formation of a highly hydrophilic surface for the film having a medium Cu concentration. For this sample photocatalytic assays, performed by methylene blue discoloration, show the highest activity. The proposed mechanism of the catalytic effect, taking place on Ti/Cu sites, is supported by results obtained by theoretical calculations. (C) 2010 Elsevier B.V. All rights reserved.

Wettability of Aqueous Rhamnolipids Solutions Produced by Pseudomonas aeruginosa LBI

The wetting behavior of rhamnolipids produced by Pseudomonas aeruginosa LBI strain grown on waste oil substrate and sodium dodecyl sulfate (SDS) on glass, polyethylene terephthalate (PET), poly(vinyl chloride) (PVC), poly(epsilon-caprolactone) (PCL) and polymer blend (PVC-PCL) was investigated by the measuring contact angle of sessile drops, to determine the wetting characteristics of rhamnolipids. The comparison of the wetting profiles showed that at low SDS and rhamnolipid concentrations, the contact angle increased and when the concentration of the surfactant increased further, the contact angle decreased. The blend surface (PVC-PCL) showed better wettability than the homopolymers themselves and the blend changed the surface hydrophobicity of the polymer, making it more hydrophilic. The rhamnolipids produced by the LBI strain exhibited superior wetting abilities than the chemical surfactant SDS one. This is the first work that evaluates the wetting properties of rhamnolipids on polymer blends.

Sisal chemically modified with lignins: Correlation between fibers and phenolic composites properties

Sisal fibers have been chemically modified by reaction with lignins, extracted from sugarcane bagasse and Pinus-type wood and then hydroxymethylated, to increase adhesion in resol-type phenolic thermoset matrices. Inverse gas chromatography (IGC) results showed that acidic sites predominate for unmodified/modified sisal fibers and for phenolic thermoset, indicating that the phenolic matrix has properties that favor the interaction with sisal fibers. The IGC results also showed that the phenolic thermoset has a dispersive component closer to those of the modified fibers suggesting that thermoset interactions with the less polar modified fibers are favored. Surface SEM images of the modified fibers showed that the fiber bundle deaggregation increased after the treatment, making the interfibrillar structure less dense in comparison with that of unmodified fibers, which increased the contact area and encouraged microbial biodegradation in simulated soil. Water diffusion was observed to be faster for composites reinforced with modified fibers, since the phenolic resin penetrated better into modified fibers, thereby blocking water passage through their channels. Overall, composites` properties showed that modified fibers promote a significant reduction in the hydrophilic character, and consequently of the reinforced composite without a major effect on impact strength and with increased storage modulus. (c) 2008 Elsevier Ltd. All rights reserved.

Cassava bagasse cellulose nanofibrils reinforced thermoplastic cassava starch

Cellulose cassava bagasse nanofibrils (CBN) were directly extracted from a by-product of the cassava starch (CS) industry, viz. the cassava bagasse (CB), The morphological structure of the ensuing nanoparticles was investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), presence of other components such as sugars by high performance liquid chromatography (HPLC), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) experiments. The resulting nanofibrils display a relatively low crystallinity and were found to be around 2-11 nm thick and 360-1700 nm long. These nanofibrils were used as reinforcing nanoparticles in a thermoplastic cassava starch matrix plasticized using either glycerol or a mixture of glycerol/sorbitol (1:1) as plasticizer. Nanocomposite films were prepared by a melting process. The reinforcing effect of the filler evaluated by dynamical mechanical tests (DMA) and tensile tests was found to depend on the nature of the plasticizer employed. Thus, for the glycerol-plasticized matrix-based composites, it was limited especially due to additional plasticization by sugars originating from starch hydrolysis during the acid extraction. This effect was evidenced by the reduction of glass vitreous temperature of starch after the incorporation of nanofibrils in TPSG and by the increase of elongation at break in tensile test. On the other hand, for glycerol/sorbitol plasticized nanocomposites the transcrystallization of amylopectin in nanofibrils surface hindered good performances of CBN as reinforcing agent for thermoplastic cassava starch. The incorporation of cassava bagasse cellulose nanofibrils in the thermoplastic starch matrices has resulted in a decrease of its hydrophilic character especially for glycerol plasticized sample. (C) 2009 Elsevier Ltd. All rights reserved.

A combined X-ray and theoretical study of flavonoid compounds with anti-inflammatory activity

The structure of 7,4`-dimethoxy-3`-acetylflavone (tithonin-Ac) has been determined by X-ray diffraction and its geometry is compared with optimized geometrical parameters obtained by means of density functional theory at the B3LYP/6-311++G(d,p) level of calculation. in addition, vertical ionization potential (IPv) and acidity for tithonin-Ac and two derivatives have been also calculated. Calculations of spin densities were also performed for the radical formed by the electron abstraction of other flavones. The unpaired electron is located on C3 carbon atom (21-25%). (C) 2008 Elsevier B.V. All rights reserved.

Understanding Wax Printing: A Simple Micropatterning Process for Paper-Based Microfluidics

This technical note describes a detailed study on wax printing, a simple and inexpensive method for fabricating microfluidic devices in paper using a commercially available printer and hot plate. The printer prints patterns of solid wax on the surface of the paper, and the hot plate melts the wax so that it penetrates the full thickness of the paper. This process creates complete hydrophobic barriers in paper that define hydrophilic channels, fluid reservoirs, and reaction zones. The design of each device was based on a simple equation that accounts for the spreading of molten wax in paper.

Paper Microzone Plates

This paper describes 96- and 384-microzone plates fabricated in paper as alternatives to conventional multi-well plates fabricated in molded polymers. Paper-based plates are functionally related to plastic well plates, but they offer new capabilities. For example, paper-microzone plates are thin (similar to 180 mu m), require small volumes of sample (5 mu L per zone), and can be manufactured from inexpensive materials ($0.05 per plate). The paper-based plates are fabricated by patterning sheets of paper, using photolithography, into hydrophilic zones surrounded by hydrophobic polymeric barriers. This photolithography used an inexpensive formulation photoresist that allows rapid (similar to 15 min) prototyping of paper-based plates. These plates are compatible with conventional microplate readers for quantitative absorbance and fluorescence measurements. The limit of detection per zone loaded for fluorescence was 125 fmol for fluorescein isothiocyanate-labeled bovine serum albumin, and this level corresponds to 0.02 the quantity of analyte per well used to achieve comparable signal-to-noise in a 96-well plastic plate (using a solution of 25 nM labeled protein). The limits of detection for absorbance on paper was aproximately 50 pmol per zone for both Coomassie Brilliant Blue and Amaranth dyes; these values were 0.4 that required for the plastic plate. Demonstration of quantitative colorimetric correlations using a scanner or camera to image the zones and to measure the intensity of color, makes it possible to conduct assays without a microplate reader.

A study of slag corrosion of oxides and oxide-carbon refractories during steel refining

The use of ceramic material as refractories in the manufacturing industry is a common practice worldwide. During usage, for example in the production of steel, these materials do experience severe working conditions including high temperatures, low pressures and corrosive environments. This results in lowered service lives and high consumptions of these materials. This, in turn, affects the productivity of the whole steel plant and thereby the cost. In order to investigate how the service life can be improved, studies have been carried out for refractories used in the inner lining of the steel ladles. More specifically, from the slag zone, where the corrosion is most severe. By combining thermodynamic simulations, plant trails and post-mortem studies of the refractories after service, vital information about the behaviour of the slagline refractories during steel refining and the causes of the accelerated wear in this ladle area has been achieved. The results from these studies show that the wear of the slagline refractories of the ladle is initiated at the preheating station, through reduction-oxidation reactions. The degree of the decarburization process is mostly dependent on the preheating fuel or the environment. For refractories without antioxidants, refractory decarburization is slower when coal gas is used in ladle preheating than when a mixture of oil and air is used. In addition, ladle preheating of the refractories without antioxidants leads to direct wear of the slagline refractories. This is due to the total loss of the matrix strength, which results in a sand-like product. Thermal chemical changes that take place in the slagline refractories are due to the MgO-C reaction as well as the formation of liquid phases from impurity oxides. In addition, the decrease in the system pressure during steel refining makes the MgO-C reaction take place at the steel refining temperatures. This reduces the refractory’s resistance to corrosion. This is a serious problem for both the magnesia-carbon and dolomite-carbon refractories. The studies of the reactions between the slagline refractories and the different slag compositions showed that slags rich in iron oxide lead mostly to the oxidation of carbon/graphite in the carbon-containing refractories. This leads to an increased porosity and wettability and therefore an enhanced penetration of slag into the refractory structure. If the slag contains high contents of alumina and or silica (such as the steel refining slag), reactions between the slag components and the dolomite-carbon refractory are promoted. This leads to the formation of low-temperature melting phases such as calcium-aluminates and silicates. The state of these reaction products during steel refining leads to an accelerated wear of the dolomite-carbon refractory. The main products of the reactions between the magnesia-carbon refractory and the steel refining slag are MgAl2O4 spinels, and calcium-aluminates, and silicates. Due to the good refractory properties of MgAl2O4 spinels, the slag corrosion resistance of the magnesiacarbon refractory is promoted.

Synthesis of a PEG-bipolar-dimyristoylphosphatidylethanoline

The problem of drug delivery has been of continuous research interest to the biomedical scientific community. The basic problem of drug delivery is to facilitate the transport of medication via the bloodstream to the target organs. This process can be significantly hampered by the hydrophobic nature of most medications. Pharmaceutical compounds and in particular chemotherapeutics (which are a specific area of research at the Cornell Medical Center and the Sloan-Kettering Institute) tend to be extremely hydrophobic. Blood is a hydrophilic environment, so the hydrophobic drugs simply cannot dissolve in the bloodstream. As a result they cannot be transported successfully to the target tissues. For example, Sloan-Kettering possesses compounds that kill cancer cells 100ln vitro, yet those same compounds are virtually inactive in vivo because of their insolubility in the blood. It was our purpose, therefore, to develop an appropriate and successful drug delivery system.