A new insight on the preparation of stabilized alpha-nickel hydroxide nanoparticles

Nickel hydroxide can provide an outstanding cathode material in alkaline secondary batteries, however the progressive decrease of the charge capacity as a function of the number of oxidation/reduction cycles is a challenging problem to be solved. New improvements on the electrochemical properties of electrode materials can be achieved by exploiting the much better performance of alpha-nickel hydroxide. Such materials were obtained in a stable form by sol-gel method and characterized by thermogravimetric analyses, UV-Vis spectroscopy, X-ray diffractometry, scanning and transmission electron microscopy, cyclic voltammetry and electrochemical quartz crystal microbalance techniques. The results revealed not only the formation of the alpha-Ni(OH)2 phase, but also a much better electrochemical reversibility and stability as compared with similar materials obtained by electrochemical precipitation method.     

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., 2011. © 2010 Society of Plastics Engineers.     

Synthesis and deposition of bismuth oxychloride with a rose-type flower shape and photoelectroactivity evaluation in the methyl orange discoloration reaction

In this work, bismuth oxychloride with a rose-type flower shape was successfully synthesised using the easy and low-cost successive ionic layer adsorption and reaction process. The tetragonal crystalline structure with a flower-like shape and thickness of 150-nm nanosheets was used as electrode material in an exciting approach for the photoelectrochemical discoloration reaction of methyl orange. The structure, morphology and optical properties of the obtained bismuth oxychloride sample were evaluated through X-ray diffraction, Raman spectroscopy, the Brunauer–Emmett–Teller method, diffuse reflectance ultraviolet–visible spectroscopy and scanning electron microscopy. Through photoelectrochemical characterisation measurements (linear sweep voltammetry, chronoamperometry and electrochemical impedance spectroscopy techniques), the bismuth oxychloride electrode showed remarkable electroactivity under ultraviolet light irradiation. The methyl orange discoloration reaction, performed under ultraviolet light incidence and potential application of −0.5 V (vs silver/silver chloride) for 60 minutes, produced a higher degradation percentage (ca. 82%) and k_obs of 29 × 10⁻³ min⁻¹.     

Paraquat-loaded alginate/chitosan nanoparticles: preparation, characterization and soil sorption studies

Agrochemicals are amongst the contaminants most widely encountered in surface and subterranean hydrological systems. They comprise a variety of molecules, with properties that confer differing degrees of persistence and mobility in the environment, as well as different toxic, carcinogenic, mutagenic and teratogenic potentials, which can affect non-target organisms including man. In this work, alginate/chitosan nanoparticles were prepared as a carrier system for the herbicide paraquat. The preparation and physico-chemical characterization of the nanoparticles was followed by evaluation of zeta potential, pH, size and polydispersion. The techniques employed included transmission electron microscopy, differential scanning calorimetry and Fourier transform infrared spectroscopy. The formulation presented a size distribution of 635 ± 12 nm, polydispersion of 0.518, zeta potential of -22.8 ± 2.3 mV and association efficiency of 74.2%. There were significant differences between the release profiles of free paraquat and the herbicide associated with the alginate/chitosan nanoparticles. Tests showed that soil sorption of paraquat, either free or associated with the nanoparticles, was dependent on the quantity of organic matter present. The results presented in this work show that association of paraquat with alginate/chitosan nanoparticles alters the release profile of the herbicide, as well as its interaction with the soil, indicating that this system could be an effective means of reducing negative impacts caused by paraquat.     

Contact thermal post-treatment of oriented strandboard to improve dimensional stability: A preliminary study

The oriented strandboard (OSB) has less dimensional stability than plywood, but they are competitive panels and have been used for similar ends. The wood-water relation variables, such as thickness swelling and water absorption, express this OSB dimensional instability and can be explained by two main factors: wood hygroscopicity and imposed hot-pressing stresses. The objective of this present paper was to propose a thermal post-treatment as a method to improve OSB dimensional stability by decreasing wood hygroscopicity and releasing hot-pressing stress. OSB panels from Pinus taedawood were produced in laboratory, and their characteristics were: single layer, 0.8 g/cm³; 8% phenolic resin and without wax. The OSB panels were treated in a laboratory press at 250 °C for about 4, 7 and 10 minutes. The wood-water relation variables, thickness swelling (TS), water absorption (WA), equilibrium moisture content (EMC) and springback or permanent thickness swelling (PTS) were determined and compared with untreated panels. The results showed that the proposed thermal treatment was effective to reduce TS, EMC and PTS, but didn’t affect WA which was affected by panel density reduction. The longer the treatment the higher the dimensional stability, and panel weight loss could be used as predictive variable for the efficiency of the treatment.     

Pharmacological Evaluation and Preparation of Nonsteroidal Anti-Inflammatory Drugs Containing an N-Acyl Hydrazone Subunit

A series of anti-inflammatory derivatives containing an N-acyl hydrazone subunit (4a–e) were synthesized and characterized. Docking studies were performed that suggest that compounds 4a–e bind to cyclooxygenase (COX)-1 and COX-2 isoforms, but with higher affinity for COX-2. The compounds display similar anti-inflammatory activities in vivo, although compound 4c is the most effective compound for inhibiting rat paw edema, with a reduction in the extent of inflammation of 35.9% and 52.8% at 2 and 4 h, respectively. The anti-inflammatory activity of N-acyl hydrazone derivatives was inferior to their respective parent drugs, except for compound 4c after 5 h. Ulcerogenic studies revealed that compounds 4a–e are less gastrotoxic than the respective parent drug. Compounds 4b–e demonstrated mucosal damage comparable to celecoxib. The in vivo analgesic activities of the compounds are higher than the respective parent drug for compounds 4a–b and 4d–e. Compound 4a was more active than dipyrone in reducing acetic-acid-induced abdominal constrictions. Our results indicate that compounds 4a–e are anti-inflammatory and analgesic compounds with reduced gastrotoxicity compared to their respective parent non-steroidal anti-inflammatory drugs.     

Rheology of Cement Mortars with Crushed Fine Aggregates of Different Lithological Types

Crushed fine aggregates are widely used for full or partial replacement of natural sands in concretes. The crushed sands present different characteristics from the natural sand, especially if taking into account the content of microfine particle, the distribution of particle sizes, the shape features, besides the different lithological origin. From the rheological point of view, the crushed sands frequently provide mixtures with high yield stress, high viscosity, high cohesion and internal friction, which hinders its use in concrete. This study is focused on the evaluation of the rheological behavior of concrete mortar phase when using different lithological types of crushed sand in total replacement of natural sand. The lithological types surveyed were granite, calcitic limestone, dolomite limestone and mica schist. Each of these sand types was studied in two ways： in natura and with adjusted grading curve. The results show the best performance of calcitic limestone providing lower viscosities and lower yield stress in mortars.     

Classification of cassava starch films by physicochemical properties and water vapor permeability quantification by FTIR and PLS

ABSTRACT:  Cassava starches are widely used in the production of biodegradable films, but their resistance to humidity migration is very low. In this work, commercial cassava starch films were studied and classified according to their physicochemical properties. A nondestructive method for water vapor permeability determination, which combines with infrared spectroscopy and multivariate calibration, is also presented. The following commercial cassava starches were studied: pregelatinized (amidomax 3550), carboxymethylated starch (CMA) of low and high viscosities, and esterified starches. To make the films, 2 different starch concentrations were evaluated, consisting of water suspensions with 3% and 5% starch. The filmogenic solutions were dried and characterized for their thickness, grammage, water vapor permeability, water activity, tensile strength (deformation force), water solubility, and puncture strength (deformation). The minimum thicknesses were 0.5 to 0.6 mm in pregelatinized starch films. The results were treated by means of the following chemometric methods: principal component analysis (PCA) and partial least squares (PLS) regression. PCA analysis on the physicochemical properties of the films showed that the differences in concentration of the dried material (3% and 5% starch) and also in the type of starch modification were mainly related to the following properties: permeability, solubility, and thickness. IR spectra collected in the region of 4000 to 600 cm⁻¹ were used to build a PLS model with good predictive power for water vapor permeability determination, with mean relative errors of 10.0% for cross-validation and 7.8% for the prediction set.     

Optimization of Extraction Parameters of Total Phenolics from <Emphasis Type="Italic">Annona crassiflora</Emphasis> Mart. (Araticum) Fruits Using Response Surface Methodology

In this study, response surface methodology was used to optimize the extraction temperature (25–75 °C) and ethanol concentration (0–70 %, ethanol/water, v/v) to maximize the extraction of total phenolic compounds (TPC) from araticum pulp. The efficiency of the extraction process was monitored over time, and equilibrium conditions were reached between 60–90 min. A second-order polynomial model was adequately fit to the experimental data with an adjusted R ² of 0.9793 (p < 0.0001) showing that the model could efficiently predict the TPC content. Optimum extraction conditions were ethanol concentration of 46 % (v/v), extraction temperature of 75 °C and extraction time of 90 min. Under the optimum conditions, the araticum pulp showed high TPC content (4.67 g GAE/100 g dw) and also high antioxidant activity in the different assays used (46.56 μg/mL, 683.65 μmol TE/g and 1593.72 μmol TE/g for DPPH IC₅₀, TEAC and T-ORAC_FL, respectively). From our extraction procedure, we successfully recovered a significantly higher amount of TPC compared to other studies in the literature to date (1.5–22-fold higher). Furthermore, TPC and antioxidant activity were present in the fruit in levels that are difficult to find in other common fruits. These results expose a potential approach for improving human health through consumption of araticum fruit.