Multifunctional natural fibers: the potential of core shell MgO–SiO2 nanoparticles

Cellulose - Core–shell nanoparticles (NPs) based on metal oxides, namely magnesium oxide (MgO) and silica (SiO2), are a fantastic alternative for natural fibers’ functionalization. In...     

Braided reinforced composite rods for the internal reinforcement of concrete

This paper reports on the development of braided reinforced composite rods as a substitute for the steel reinforcement in concrete. The research work aims at understanding the mechanical behaviour of core-reinforced braided fabrics and braided reinforced composite rods, namely concerning the influence of the braiding angle, the type of core reinforcement fibre, and preloading and postloading conditions. The core-reinforced braided fabrics were made from polyester fibres for producing braided structures, and E-glass, carbon, HT polyethylene, and sisal fibres were used for the core reinforcement. The braided reinforced composite rods were obtained by impregnating the core-reinforced braided fabric with a vinyl ester resin. The preloading of the core-reinforced braided fabrics and the postloading of the braided reinforced composite rods were performed in three and two stages, respectively. The results of tensile tests carried out on different samples of core-reinforced braided fabrics are presented and discussed. The tensile and bending properties of the braided reinforced composite rods have been evaluated, and the results obtained are presented, discussed, and compared with those of conventional materials, such as steel. Russian translation published in Mekhanika Kompozitnykh Materialov, Vol. 44, No. 4, pp. 327–338, May–June, 2008.     

Silk‐Ion Jelly: a novel ion conducting polymeric material with high conductivity and excellent mechanical stability

In this work, a thin, flexible and mechanically stable polymer conducting material (Silk‐Ion Jelly) was developed though application of Ion Jelly on to silk fabrics. Ion Jelly was prepared through jellification of a room temperature ionic liquid, 1‐butyl‐3‐methyl‐imidazolium dicyanamide ([bmim][dca]) using gelatin and water and applied to silk fabrics using two different processes: impregnation and in‐situ. Various parameters influencing ionic conductivity such as Ion Jelly composition (ratio of [bmim][dca], water and gelatin) and incorporation as well as the type of application process were thoroughly investigated. It was observed that the Ion Jelly compositions containing lower gelatin and water ratio as well as application through in‐situ process at high temperature (200 °C) led to considerable improvement in conductivity, mainly due to increased [bmim][dca] concentration, structural flexibility and reduced silk crystallinity. Silk‐Ion Jelly prepared using optimized conditions showed excellent mechanical stability and possessed high room temperature conductivity (2.9 × 10^?3 S. cm^?1), similar to [bmim][dca], and therefore, this novel ion conducting material may find potential applications in electrochemical devices due to its eco‐friendly preparation route using biomaterials and green solvents. Copyright © 2012 John Wiley & Sons, Ltd.     

A Review of Multiple Scale Fibrous and Composite Systems for Heating Applications

Different types of heating systems have been developed lately, representing a growing interest in both the academic and industrial sectors. Based on the Joule effect, fibrous structures can produce heat once an electrical current is passed, whereby different approaches have been followed. For that purpose, materials with electrical and thermal conductivity have been explored, such as carbon-based nanomaterials, metallic nanostructures, intrinsically conducting polymers, fibers or hybrids. We review the usage of these emerging nanomaterials at the nanoscale and processed up to the macroscale to create heaters. In addition to fibrous systems, the creation of composite systems for electrical and thermal conductivity enhancement has also been highly studied. Different techniques can be used to create thin film heaters or heating textiles, as opposed to the conventional textile technologies. The combination of nanoscale and microscale materials gives the best heating performances, and some applications have already been proven, even though some effort is still needed to reach the industry level.     

Surface Modification of Banana Fibers by DBD Plasma Treatment

Banana fibers, an environmentally friendly raw material freely available, were physically modified by atmospheric dielectric barrier discharge (DBD) plasma treatment of different dosages. The influence of the plasma treatment applied on the banana fibers was performed considering the mechanical properties, wettability, chemical composition and surface morphology. These properties were evaluated by tensile tests, static and dynamic contact angle, Fourier transform infrared spectroscopy, energy dispersive spectroscopy, X-ray diffractometry, conductivity and pH of aqueous extract, differential scanning calorimetry and scanning electron microscopy images. We compare untreated and treated fibers with three different DBD plasma dosages. The results of this study showed considerable modifications in banana fibers when these are submitted to plasma treatment.     

Kinetic approach to heavy metal mobilization assessment in sediments: choose of kinetic equations and models to achieve maximum information

Studies of trace metal mobilization in sediments are generally performed using sequential extraction schemes at equilibrium. In the present work, a kinetic fractionation of trace metals in sediments has been developed to assess that information. The extraction rate data have been obtained using a single extraction scheme with EDTA and following a protocol previously optimized. Two kinetic equations and two kinetic models were used to fit the experimental data. The two constants equation fits well the extraction rate data used in this work but does not present any physico-chemical meaning. The diffusion model and the two first-order reactions model allow determining which parameter (the reaction between the metal M and the EDTA or the diffusion of the complex M/EDTA) is rate limiting in the trace metal extraction by EDTA. It appears that the two first-order reactions model is more efficient than the diffusion model to fit the present extraction rate data so it can be deduced that the diffusion of the complex M/EDTA is not the limiting step of the trace metal extraction by EDTA in estuarine sediments. In a second part, relationships between the fraction of metals determined with the two first-order reactions model and the sediments composition were established.     

Thermodynamic behavior of lipid nanoparticles upon delivery of Vitamin E derivatives into the skin: in vitro studies

This article reports the thermodynamic changes of lipid nanoparticles (LN) upon delivery of lipophilic vitamin E derivatives to the skin. Skin penetration of α-tocopherol (α-T) and α-tocopherol acetate (α-Ta) into and across porcine ear skin was investigated in vitro using tape-stripping test in modified Franz diffusion cells. Wide angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC) have been used to characterize the polymorphism of the solid matrix of LN before and after in vitro skin penetration assay. Cetyl palmitate LN with a loading capacity of 20% of vitamin E derivatives (with regard to the lipid matrix) have shown the typical β’ modification of waxes, with a crystallinity index (%CI) between 30 and 40%. Mean particle size and shelf life stability was assessed by static (laser diffractometry, LD) and dynamic (photon correlation spectroscopy, PCS) light scattering techniques. Submicron-sized LN were produced, i.e., 99% of LN showed a size below 600 nm immediately after production. A mean size between 180 and 350 nm (polydispersity index < 0.25) was obtained for LN stored at both 8 and 22 °C, and this size range was kept constant for at least 20 days of shelf life. Quantification of α-T and α-Ta in the skin using tape-stripping provided a 3.4-fold increase in the level of actives within the stratum corneum (SC) and 1.3-fold increase in the viable epidermis (VE). LN increased skin penetration of both actives, following a cumulative release during 8 h in modified Franz diffusion cells. The differences in the distribution levels observed between α-T and α-Ta when delivered via LN was due to the different thermodynamic activity of both actives, i.e., following increased partition coefficient of α-Ta into SC and VE, in comparison to α-T.     

Long-term release of carbon from grassland soil amended with different slurry particle size fractions: a laboratory incubation study

Application of animal manure to agricultural soils enhances both native soil carbon (C) and overall (native soil C and added C) respiration. CO(2) effluxes were measured in a laboratory incubation study for 1465 days after the application of different slurry fractions (>2000, 425-2000, 250-425, 150-250, 45-150 and <45 μm) to a grassland soil. The slurry-derived C present in the soil was traced using the natural abundance δ(13)C method. We used two kinetic (single and two pool) models to fit the experimental data and to test the model validity with respect to long-term data sets. Mean residence times (MRTs) of the particle size based slurry-C fractions were estimated using these models and a linear (13)C natural abundance based approach. The results showed that slurry-C degradation in soil over time varied between the different particle size based slurry treatments. The two kinetic soil-C models were successful to predict medium- to long-term carbon release from soil amended with animal slurry. The estimated MRTs did vary between the linear (3.8-5.6 years) and non-linear based (0.8-3.8 years) (model) approaches. Slurry-derived C could still be (isotopically) detected in the soil 4 years after slurry application using the natural abundance δ(13)C method. This suggests that it may take a decadal timescale or longer before the entire amount of C introduced through whole slurry amendments to grassland soils is fully dissipated.