Unsaturated Polyester-Based Polymer Concrete Containing Recycled Cathode Ray Tube Glass Aggregate

Polymer concrete (PC) is a composite construction material that boasts several advantages, such as lightness, low water permeability, high resistance to corrosive environments, and chemical degradation. Consequently, it has recently attracted interest as an alternative material to the traditional ones for several civil applications. In this study, unsaturated polyester resin was considered the matrix phase of PC. Aimed to produce green PC, the commonly dispersed phase of natural aggregate was totally replaced by recycled glass aggregate (RGA) deriving from cathode ray tube (CRT) glass waste. Fine and coarse fractions of non-hazardous CRT glass were considered in different ratios. Chemical and physical analyses were carried out through XRF, particle size distribution and microstructural analysis to characterize RGA. The influence of RGA particle size and percentage on PC performance was investigated by microstructural analysis and aggregate packing, chemical resistance, water absorption, and mechanical analyses, such as bending, impact, and scratch test. Using solely the coarse fraction of RGA led to the manufacturing of a green PC with similar performance to the traditional PC and in addition lower in density. The PC quality mainly depended on the matrix crosslinking which, for PC containing fine RGA, was promoted by adding 4 wt% of silane coupling agent

Development of a Solar-reflective Ceramic Tile Ready for Industrialization

Solar-reflective surfaces represent an effective countermeasure to UHI. The market of "cool" materials is dominated by polymeric solutions which, under UV exposure, are damaged. On the other hand, an increasing attention was paid recently to ceramic-based solar-reflective surfaces, characterized by very long lifespan. A ceramic tile is typically made by a three layers structure: substrate-engobe-glaze. This structure has been exploited to develop a cool ceramic tile that can be produced in the same production facilities of common products to create a whole tile by merging technological results and industrial production needs, to achieve a compromise between performance and costs

Activation of the ATPase activity of hsp90 by the stress-regulated cochaperone aha1

Client protein activation by Hsp90 involves a plethora of cochaperones whose roles are poorly defined. A ubiquitous family of stress-regulated proteins have been identified (Aha1, activator of Hsp90 ATPase) that bind directly to Hsp90 and are required for the in vivo Hsp90-dependent activation of clients such as v-Src, implicating them as cochaperones of the Hsp90 system. In vitro, Aha1 and its shorter homolog, Hch1, stimulate the inherent ATPase activity of yeast and human Hsp90. The identification of these Hsp90 cochaperone activators adds to the complex roles of cochaperones in regulating the ATPase-coupled conformational changes of the Hsp90 chaperone cycle

α-Helical conformation in the C-terminal anchoring domains of E. coli penicillin-binding proteins 4, 5 and 6

AbstractThe E. coli low molecular mass penicillin-binding proteins (PBP's) are penicillin sensitive, enzymes involved in the terminal stages of peptidoglycan biosynthesesis. These PBP's are believed to anchor to the periplasmic face of the inner membrane via C-terminal amphiphilic α-helices but to date the only support for this hypothesis has been obtained from theoretical analysis. In this paper, the conformational behaviour of synthetic peptides corresponding to these C-terminal anchoring domains was studied as a function of solvent, pH, sodium dodecyl sulphate micelles and phospholipid (DOPC, DOPG) vesicles using circular dichroism (CD) spectroscopy. The CD data showed that in 2,2,2-trifluoroethanol or sodium dodecylsulphate, all three peptides have the capacity to form an α-helical conformation but in aqueous solution or in the presence of phospholipid vesicles only those peptides corresponding to the PBP5 and PBP6 C-termini were observed to do so. A pH dependent loss of α-helical conformation in the peptide corresponding to the PBP5 C-terminus was found to correlate with the susceptibility of PBP5 to membrane extraction. This correlation would agree with the hypothesis that an α-helical conformation is required for membrane interaction of the PBP5 C-terminal region

Preparation and Characterization of LAS Glass Based Materials for Dental Applications

Glass ceramic materials are widely used in dental application because of their strong similarity with natural teeth. In this study LAS glass ceramic/glass materials were prepared by glazing processing and characterized in terms of mechanical flexural strength. The selected glass ceramic support derives from an industrial process. Different glasses were applied to the glass ceramic support in order to investigate firstly their effect on the glass ceramic/glass interface and secondly how these structural changes are correlated to the flexural strength property. Different thermal cycles were applied to the glass ceramic in order to promote the increasing of mechanical flexural strength. Preliminary results clearly points out that the application of a glass on the support leads to the decrease of the flexural strength if compared to the materials without any coating applied

Insight into the Structure of Vanadium containing Glasses: a Molecular Dynamics Study

In this manuscript, classical molecular dynamics simulations (MD) have been applied to study the short and medium range order of very complex vanadium containing glasses with the aim of improving the first microscopic picture of such materials. A rigid ionic force-field has been extended to include the V5+-O, V4+-O and Cu2+-O interatomic pair parameters and tested to reproduce structural properties of known crystal phases with quite good accuracy. Then the structure of Na2O-SiO2, CaO-MgO-Al2O3-SiO2 and Na2O-P2O5 glass compositions in which vanadium is present in the range 1-72 wt% (0.3-60 mol.%) have been fully described in terms of vanadium local structure and Qn distributions. A fairly good agreement was found with experimental data further validating our computational models and providing a computational approach that could be used and extend to investigate in detail the structural information (V-V distances, V-O-V linkages and BO/NBO) directly correlated to macroscopic properties of application interest

EFFECT OF FORMING PRESSURE ON THE REACTIVITY AND MICROSTRUCTURE OF ZIRCON POWDER COMPACTS

Preliminary results of a study on the effects of the forming pressure on the reactivity, sintering and microstructure of very fine natural zircon powder compacts. The effects of compaction pressure on the green densities and sintered densities are also discussed. The relationship between the density and the compaction pressure governs the mechanism that occurs in the consolidation process. The investigation has demonstrated changing the compaction pressure in the range 45-180MPa does not influence the onset temperature of sintering of powdered zircon (1150-1170 °C) but does influence the apparent density of the green compacts and consequently the porosity of the sintered specimens. Low relative density values were obtained in these sintering conditions