Microwave-Assisted Bleaching of Wool Fabrics

Microwave irradiation was used to reduce consumption of energy and time during bleaching of wool fabrics with hydrogen peroxide. The effect of some reaction conditions; viz. hydrogen peroxide concentration, treatment time, presence of stabilizer, on degree of whiteness imparted to bleached wool, was studied systematically. Comparative study between bleaching of wool using microwave irradiation and conventional heating was undergone. The effect of bleaching of wool on its morphological structure was assigned by scanning electron microscopy. The change in some chemical and physicomechanical characteristics of bleached wool was monitored; namely whiteness index, alkali solubility, wettability, critical surface area, tensile strength, and elongation at break, of the treated as well as untreated fabrics were measured. The microwave-assisted bleaching of wool resulted in improved degree of whiteness comparable to that is obtained using conventional heating method. However, the microwave-assisted bleached wool shows lower degree of deterioration than that of conventionally bleached wool. The COD and BOD of the wool bleaching effluents were determined.     

Adaptive and dual data-communication trust scheme for clustered wireless sensor networks

In wireless sensor networks, trust management schemes are designed to preserve them against misbehavior of malicious sensor nodes. These schemes observe the behavior of nodes, check their conformity to what is expected, compute and assign them trust values, and avoid any interaction with untrustworthy nodes. In this paper, we introduce Adaptive and dual Data-Communication Trust scheme (ADCT) for clustered wireless sensor networks to effectively deal with untrustworthy nodes. Unlike prior works, we propose an adaptive trust function to assess the direct trust between nodes according to the application’s requirement in terms of trust severity. We also consider data trust to cope with untrustworthy nodes during the data collection despite their communication capabilities. Moreover, we use the duality data-communication trust to deal with untrustworthy recommendations when building cluster-member’s feedback at the cluster-head level. Theoretical analysis and simulation show that the trust mechanism presented in this paper provides a better cooperation with the same or even lower communication overhead compared to the latest trust management schemes proposed for clustered wireless sensor networks.     

Aspergillus section Flavi and aflatoxins in dried figs and nuts in Algeria

The presence of Aspergillus section Flavi and aflatoxin (AF) contamination was investigated in 112 samples of peanuts, almonds and dried figs collected in Algeria. The occurrence of aflatoxin B1 (AFB1), B2 (AFB2), G1 (AFG1) and G2 (AFG2) in different commodities has been determined with a sensitive method based on high performance liquid chromatography (HPLC) coupled with fluorescence detection with post-column photochemical derivatisation. Analytical results indicated that 28 samples of peanuts, 16 samples of almonds and 26 samples of dried figs contained detectable levels of AFs. A total of 69 samples (61.6%) were contaminated with AFB1 ranging from the limit of quantification to 174 µg kg^?1. AFB2 was found in 12 samples (10.7%) and varied from 0.18 to 193 µg kg^?1. Seven samples revealed AF concentrations lower than the limit of quantification. Eleven peanut and fourteen dried fig samples exceeded the European maximum limits for AFB1.     

Conduction properties of condensed lanthanum phosphates:La(PO3)3 and LaP5O14

Single crystals of LaP3O9·3H2O were prepared using a classical method of aqueous chemistry whereas those of the ultraphosphate LaP5O14 were obtained by flux method.Thermal treatment of LaP3O9·3H2O up to 700 °C allowed us to obtain the lanthanum polyphosphate La(PO3)3.The conductivity as well as the vibrational study of the lanthanum ultraphosphate and polyphosphate were analysed in order to explain the mechanism of conduction.Activation energies of 0.45 and 0.84 eV,deduced from the Arrhenius relation,were respectively found for the polyphosphate and the ultraphosphate.Taking into account the structural features of these materials we linked the origin of their electrical properties to the incorporation of atmospheric humidity.Thus,it was a proton conduction phenomenon which took place as a result of the establishment of hydrogen bonds as well as the reorganisation of water molecules already incorporated into these structures.Referring to the Grotthuss mechanism,a proton transfer model inside the polyphosphate's structure was suggested.     

Use of a PbO2 electrode of a lead-acid battery for the electrochemical degradation of methylene blue

In this work, the electrochemical degradation efficiency of synthetic azo dye, methylene blue, at positive electrode PbO₂ of lead-acid battery was investigated. The structure and morphology of the electrode was investigated by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectrometry. The influence of several operating parameters on electro-oxidation of 100 mL of methylene blue solution 100 mg/L was studied. Results indicated that lead-acid battery electrode is effective for removing color and chemical oxygen demand (COD). It is found that current density, the stirring speed, and the supporting electrolyte concentration have a positive effect on decolorization and mineralization, and no significant effect of the distance between the electrodes on methylene blue degradation and COD removal was observed. By contrast, the percentage of color and COD removal decreases with increasing of pH. Kinetic analysis of the results revealed that the COD removal follows a pseudo-first-order kinetics.     

Electrical conductivity of La1−xCaxFeO3−δ solid solutions

La_1−xCa_xFeO_3−δ solid solutions (x=0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) were investigated. The samples were prepared by the polymerizable complex route and characterized by X-ray diffraction and complex impedance spectroscopy techniques. Results reveal the formation of a single perovskite phase for the La_1−xCa_xFeO_3−δ (0≤x≤0.5) compositions. However, the La_0.4Ca_0.6FeO_3−δ sample is a mixture of many phases: perovskite, calcium ferrite and iron oxide. The unsubstituted lanthanum ferrite oxide, as well as the substituted samples, exhibits an orthorhombic symmetry. The direct current conductivity analyses reveal a typical negative temperature coefficient of the resistance behaviour for all the samples. The incorporation of calcium into the lanthanum ferrite lattice results in a significant improvement of the direct current conductivity. In fact, La_0.8Ca_0.2FeO_3−δ oxide shows the optimal conduction value. For all the studied compositions, a change in the activation energy is highlighted around 440 °C. This behaviour is attributed to the antiferromagnetic to paramagnetic transition of lanthanum ferrite. As for the alternating current conductivity, it obeys the Jonsher's power law. The correlated barrier hopping model is proposed to describe the transport mechanism in the studied matrix.     

Phosphonium iodine as nickel corrosion inhibitor in 1 M sulfuric acid medium

The inhibiting action of alkyltriphenylphosphonium iodine salt ((C₈H₁₇)Ph₃P⁺,I⁻) towards the corrosion behaviour of nickel in 1 M H₂SO₄ solution has been studied. This compound was found to retard both anodic and cathodic reactions of nickel corrosion. At constant temperature, the corrosion rate decreases with increasing inhibitor concentration. On the other hand, the increase in temperature leads to an increase in the corrosion rate. The activation energy, ΔE _a, were calculated. They were found 19.3 kJ mol⁻¹ and 71.1 kJ mol⁻¹, respectively for the uninhibited solution and in the presence of 10⁻³ M of phosphonium salt. The inhibitor adsorption was identified to occur according to Langmuir isotherm. The equilibrium constant, k, as well as the free energy of adsorption, Δ_ads G°, for inhibitor process were then calculated. Phosphonium iodine exhibited a singular behaviour for T ≥ 318 K where inhibitor desorption increases.     

Antimicrobial activity of novel biocompatible wound dressings based on triblock copolymer hydrogels

Wound infection is a common complication often resulting in delayed healing with adverse clinical and financial consequences. Current antimicrobial treatments are far from ideal, side effects can include both bacterial resistance and toxicity. As a result, a great deal of effort over the last 20 years has been spent on investigating new forms of antimicrobial dressings. Here, we report the unexpected antimicrobial activity of a relatively new biocompatible thermo-responsive PHPMA–PMPC–PHPMA triblock copolymer gelator [where PHPMA denotes poly(2-hydroxypropyl methacrylate) and PMPC denotes poly(2-(methacryloyloxy)ethyl phosphorylcholine)]. In a radial diffusion assay, a 20% w/v copolymer gel produced an inhibitory zone up to six times greater than the corresponding control against Staphylococcus aureus. Similarly, in a broth inhibition assay the same copolymer reduced bacterial growth by 45% compared with control experiments conducted in the absence of any copolymer. Moreover, addition of the copolymer to a 3D-infected skin model reduced bacterial recovery by 38% compared to that of controls over 24–48 h. This is particularly relevant since these antimicrobial triblock copolymers were recently shown to be non-toxic when exposed to a tissue-engineered skin model. This antimicrobial activity was also successfully immobilised by grafting PMPC–PHPMA diblock copolymer brushes onto silicon wafers. Our results indicate that both PMPC–PHPMA diblock and PHPMA homopolymer brushes exhibit antimicrobial activity. Our hypothesis for the mode of action is that the moderately hydrophobic PHPMA chains penetrate the bacterial membrane, causing leakage of the cell contents. In summary, these gels and surfaces offer a promising new approach to antimicrobial dressings.