High temperature and fire behaviour of continuous glass fibre/polypropylene laminates

This paper reports elevated temperature mechanical property measurements on woven glass fibre/polypropylene composites. Tensile and compressive stress rupture measurements were made on 12 mm thick laminate exposed to 50 kW m^?2 heat flux. Behaviour was qualitatively similar to that of thermosetting laminates, but compressive behaviour was significantly inferior, due to a poorer resin–matrix bond, and to the loss of compressive properties at temperatures above the melting point.COM-FIRE, a finite difference implementation of the Henderson Equation, was able to model the thermal and residual resin profiles in the laminate during fire exposure. The thermal predictions were used, in conjunction with the measured mechanical property data, to model changes in elastic properties and stress rupture behaviour in fire. Because of the non-linearity of the tensile stress–strain curves, a 3-parameter model was needed to describe behaviour. In contrast the compressive response could be modelled by a simpler 2-parameter or saw-tooth model.     

Fire protection systems for building floors made of pultruded GFRP profiles: Part 1: Experimental investigations

This paper presents results of experimental investigations on the behaviour of GFRP pultruded profiles exposed to fire, in order to study the viability of their structural use in floors of buildings, taking into account the fulfilment of fire resistance requirements. The feasibility and efficacy of using three different protective coatings/layers, often used to protect structural steel, and a water cooling system to provide fire protection to GFRP pultruded profiles were investigated. The experimental programme included dynamic mechanical analyses (DMA), thermogravimetric and differential scanning calorimetry (TGA/DSC) experiments and fire resistance tests on GFRP tubular loaded beams. The unprotected GFRP beam failed after about 38 min, the three different passive protection systems provided a fire resistance between 65–76 min and the water cooling system provided a fire resistance of at least 120 min. Failure occurred in the upper part of the beams, due to compression and shear stresses. Results of these experiments allowed defining the field of application of each investigated solution, according to building code requirements.     

Nanogeometry matters: unexpected decrease of capillary adhesion forces with increasing relative humidity

The sticking effect between hydrophilic surfaces occurring at increasing relative humidity (RH) is an everyday phenomenon with uncountable implications. Here experimental evidence is presented for a counterintuitive monotonous decrease of the capillary adhesion forces between hydrophilic surfaces with increasing RH for the whole humidity range. It is shown that this unexpected result is related to the actual shape of the asperity at the nanometer scale: a model based on macroscopic thermodynamics predicts this decrease in the adhesion force for a sharp object ending in an almost flat nanometer-sized apex, in full agreement with experiments. This anomalous decrease is due to the fact that a significant growth of the liquid meniscus formed at the contact region with increasing humidity is hindered for this geometry. These results are relevant in the analysis of the dynamical behavior of nanomenisci. They could also have an outstanding value in technological applications, since the undesirable sticking effect between surfaces occurring at increasing RH could be avoided by controlling the shape of the surface asperities at the nanometric scale.     

Best management practices for corporate, academic and governmental transfer of sustainable technologies to developing countries

Innovations with respect to technologies that contribute to environmental sustainability have emerged within national government laboratories, international agencies and within academic research institutes. Since each of these entities is understandably more focused on ab initio research, conceptual development and proofs of concept, the production level manufacturing and broad dissemination of such technologies require development of best management practices (BMPs) for effective partnerships with and/or technology licensure to private sector industry. Alternatively, certain technologies that address specific environmental sustainability needs within the developing countries can be and have been transferred directly, either through bi-lateral transfers or through multi-lateral agencies, serving as intermediaries. The appropriateness of such transfers is contingent upon host country environmental, cultural and socio-political conditions, the type of technology involved, the “terms of transfer” and the relationships established between the technology conceivers and the end-users. The authors select examples of identified modes of sustainable technology transmission and derive experiential BMPs, which may be of some utility for future sustainable technology transfer. Moreover, in providing these BMPs, the historical record and contemporary caveats with respect to unregulated technology transfer, whether sustainable or otherwise, to developing countries and the array of corresponding proposed codes of conduct are examined, given the normative objective that such technologies should ultimately contribute to ecologically benign and societally beneficial objectives, such as environmental sustainability, equitable growth and poverty alleviation. These issues and the need to establish BMPs would be broadly relevant with the new focus on climate change-related technology funds and associated regional impact projects evolving across the globe and within the developing countries in particular.     

Magnetic field sensor based on a maghemite/polyaniline hybrid material

A hybrid material containing maghemite and polyaniline (PAni) doped with dodecylbenzenesulfonic acid (DBSA) was prepared through in situ polymerization in aqueous medium. The pure maghemite powder presented average particle diameter of 10 nm and magnetization force of 14 mN. The obtained maghemite/PAni hybrid material also presented nanometric dimensions, associated with reasonable electrical conductivity (260 times larger than the electrical conductivity of the pure maghemite) and about 60% of the original magnetic force. Additionally, the electrical conductivity of the hybrid powder showed significant sensitivity to changes of the magnetic field, indicating that these materials can be useful as magnetic field sensors.     

Experimental set-up for time resolved small angle X-ray scattering studies of nanoparticles formation using a free-jet micromixer

Recently, we have designed, fabricated and tested a free-jet micromixer for time resolved small angle X-ray scattering (SAXS) studies of nanoparticles formation in the <100 μs time range. The microjet has a diameter of 25 μm and a time of first accessible measurement of 75 μs has been obtained. This result can still be improved. In this communication, we present a method to estimate whether a given chemical or biological reaction can be investigated with the micromixer, and to optimize the beam size for the measurement at the chosen SAXS beamline. Moreover, we describe a system based on stereoscopic imaging which allows the alignment of the jet with the X-ray beam with a precision of 20 μm. The proposed experimental procedures have been successfully employed to observe the formation of calcium carbonate (CaCO₃) nanoparticles from the reaction of sodium carbonate (Na₂CO₃) and calcium chloride (CaCl₂). The induction time has been estimated in the order of 200 μs and the determined radius of the particles is about 14 nm.     

Diabetic nephropathy,autophagy and proximal tubule protein endocytic transport: A potentially harmful relationship

Diabetic nephropathy (DN) is the most frequent cause of chronic renal failure. Until now, the pathophysiological mechanisms that determine its development and progression have not yet been elucidated. In the present study, we evaluate the role of autophagy at early stages of DN, induced in type 2 diabetes mellitus (T2DM) mouse, and its association with proximal tubule membrane endocytic receptors, megalin and cubilin. In T2DM animals we observed a tubule-interstitial injury with significantly increased levels of urinary GGT and ALP, but an absence of tubulointerstitial fibrosis. Kidney proximal tubule cells of T2DM animals showed autophagic vesicles larger than those observed in the control group, and an increase in the number of these vesicles marked with LBPA by immunofluorescence. Furthermore, a significant decrease in the ratio of LC3II/LC3I isoforms and in p62 protein expression in DN affected animals is shown. Finally, we observed a marked increase in urinary albumin and vitamin D binding-protein levels in T2DM animals as well as a significant decrease in expression of megalin in the renal cortex. These results indicate an alteration of the tubular endocytic transporters in DN, which could be related to autophagic dysfunction, which would in turn result in impaired organelle recycling, thus contributing to the progression of this disease.     

Antimicrobial packaging based on ɛ‐polylysine bioactive film for the control of mycotoxigenic fungi in vitro and in bread

?‐Poly‐l‐ lysine (?‐PL) is a cationic peptide with a broad‐spectrum antimicrobial activity. This study investigates the use of ?‐PL as natural antimicrobial to inhibit fungal growth and to reduce aflatoxins (AFs) production. Antifungal activity of starch biofilms with different concentrations of ?‐Poly‐l‐ lysine (?‐PL) was determined in solid medium against Aspergillus parasiticus (AFs producer) and Penicillium expansum. Then, biofilms were tested as antimicrobial devices for the preservation of bread loaf inoculated with A. parasiticus CECT 2681 and P. expansum CECT 2278. Shelf life and AFs content were examined. Biofilms with concentrations of ?‐PL less than 1.6 mg/cm² showed no fungal growth inhibition in solid medium, while the antifungal activity of the films with greater than 1.6 mg/cm² of ?‐PL was dose dependent. The shelf life of bread inoculated with A. parasiticus was increased by 1 day with the use of films containing 1.6–6.5 mg ?‐PL/cm², while shelf life of bread tainted with P. expansum was increased by 3 day with 6.5 mg ?‐PL/cm². AFs production was greatly inhibited by ?‐PL biofilms (93–100%). Thus, ?‐PL biofilms could be potentially used as antimicrobial device during bread storage as a natural alternative to the synthetic preservatives.

Practical applications

?‐Polylysin is a natural substance from microbial metabolism. Polylysine has a function to prevent a microbe from proliferating by ionic adsorption in the microbe. ?‐polylysine has a wide antibacterial spectrum and has an obvious lethal effect on Gram‐positive and Gram‐negative bacteria, yeast, mold, viruses, etc. It has a good antibacterial effect on the Gram‐negative bacteria E. coli and Salmonellae, which are difficult to control with other natural preservatives. ?‐Polylysine has already been used generally as a food additive in Japan, Korea and other part of world. In the United States, FDA has recognized the polylysine as a GRAS material. Considered the positive results obtained in the study, this compound could be used for the production of antimicrobial biofilms, applied as separator slices in the loaf bread production, to prevent the growth of the mycotoxigenic fungi A. parasiticus and P. expansum, contributing to reduce the use of the synthetically preservatives in bakery industry and also of the negative impact that these compounds could generate on the health of the end users.