Fatigue performance of flexible steel fibre reinforced rubberised concrete pavements

Recycled rubber particles and steel fibres from end-of-life tyres have the potential to enhance the flexibility and ductility of concrete pavements and produce more sustainable pavement solutions. However, the fatigue behaviour of such pavements is not fully understood. This article investigates the mechanical and fatigue performance of steel fibre reinforced concrete (SFRC) and steel fibre reinforced rubberised concrete (SFRRuC). Specimens tested were cast using rubber particles as replacement of natural aggregates (0%, 30% and 60% by volume), and using a blend of manufactured and recycled tyre steel fibres (40 kg/m3). Prisms were subjected to four-point flexural cyclic load (f = 15 Hz) at stress ratios of 0.5, 0.7, 0.8 and 0.9. The results show that, compared to plain concrete, the addition of steel fibres alone improves the fatigue stress resistance of concrete by 11% (at 25% probability of failure). The replacement of natural aggregates with rubber particles improves the flexibility of SFRRuC (from 51 GPa elastic modules for plain concrete to 13 GPa for SFRRuC), but reduces its fatigue stress resistance by 42% (at 25% probability of failure). However, a probabilistic analysis of the fatigue life data and overall design considerations show that the flexible SFRRuC can be used for pavements. To account for the effect of fatigue load, the Concrete Society approach included in TR34 is modified to account for SFRRuC pavements. Finite element analyses show that flexible SFRRuC pavements can accommodate large subgrade movements and settlements and result in much smaller cracks (up to 24 times) compared to SFRC pavements

Experimental Evaluation of the Critical Flutter Speed on Wings of Different Aspect Ratio

In this work, wind tunnel experiments were conducted to evaluate the critical flutter speed of wings for three pertinent flight parameters (i) the aspect ratio (AR), (ii) the angle of attack (AoA), and (iii) the aircraft propeller excitation. Six symmetrical wings (NACA0012 design), of fixed chord length of 80 mm and varied AR from 8.75 to 15, were used for this purpose. These wings were mounted horizontally in the wind tunnel as fixed-free condition. The airflow speed is increased slowly until the wing flutters. The results show that the critical flutter speed decreases when the AR increases. For higher AR, the effect of the AoA on the flutter speed is minimal. However, for low AR, the AoA is vital in delaying the flutter instability of the wing. This critical speed spans low to moderate Reynolds numbers based on the wing chord length (Rec =7×104-2×105) which corresponds to the speed range of High Altitude and Long Endurance (HALE) aircraft. In contrast, for a propeller excitation outside the resonance region of the wing, its effect of the on flutter characteristics is not noticeable

Durability of steel fibre reinforced rubberised concrete exposed to chlorides

This study assesses the durability and transport properties of low water/binder ratio (0.35) steel fibre reinforced rubberised concrete (SFRRuC) mixes, which are proposed to be used as flexible concrete pavements. Waste tyre rubber is incorporated in concrete as fine and coarse aggregate replacement and blends of manufactured steel fibres and recycled tyre steel fibres are used as internal reinforcement. The fresh, mechanical and transport properties of plain concrete are compared with those of SFRRuC mixes having different substitutions of rubber aggregates (0, 30 and 60% by volume). The chloride corrosion effects due to exposure to a simulated accelerated marine environment (intermittent wet-dry cycles in 3% NaCl solution) is also evaluated. The results show that, although water permeability (e.g. volume of permeable voids and sorptivity) and chloride ingress increase with rubber content, this increase is minor and water and chlorides permeability are generally within the range of highly durable concrete mixes. No visual signs of deterioration or cracking (except superficial rust) were observed on the surface of the concrete specimens subjected to 150 or 300 days of accelerated chloride corrosion exposure and a slight increase in the mechanical properties is observed. This study shows that the examined low water/binder SFRRuC mixes promote good durability characteristics, making these composite materials suitable for flexible concrete pavement applications

Hybrid technique for image compression based on five modulus method and K-L-Transform

Compression is one of the important field in digital image processing , due to that a lot of technique were adopted in this field. In this research a five modulus was applied on image compression then try to hybrid it with K-L-Transform ,then studying the efficiency of each of them individually in addition to the hybrid technique . The hybrid technique give very efficient compression ratio and also the original and retrieved image are very closed to each of them Measuring the correlation factor ,PSNR and MSE shows approach high recommended for approach

Exfoliation solvent dependent plasmon resonances in two-dimensional sub-stoichiometric molybdenum oxide nanoflakes

Few-layer two-dimensional (2D) molybdenum oxide nanoflakes are exfoliated using a grinding assisted liquid phase sonication exfoliation method. The sonication process is carried out in five different mixtures of water with both aprotic and protic solvents. We found that surface energy and solubility of mixtures play important roles in changing the thickness, lateral dimension, and synthetic yield of the nanoflakes. We demonstrate an increase in proton intercalation in 2D nanoflakes upon simulated solar light exposure. This results in substoichiometric flakes and a subsequent enhancement in free electron concentrations, producing plasmon resonances. Two plasmon resonance peaks associated with the thickness and the lateral dimension axes are observable in the samples, in which the plasmonic peak positions could be tuned by the choice of the solvent in exfoliating 2D molybdenum oxide. The extinction coefficients of the plasmonic absorption bands of 2D molybdenum oxide nanoflakes in all samples are found to be high (Îμ > 109 L mol-1 cm-1). It is expected that the tunable plasmon resonances of 2D molybdenum oxide nanoflakes presented in this work can be used in future electronic, optical, and sensing devices

Mechanical performance of steel fibre reinforced rubberised concrete for flexible concrete pavements

This work aims to develop materials for flexible concrete pavements as an alternative to asphalt concrete or polymer-bound rubber surfaces and presents a study on steel fibre reinforced rubberised concrete (SFRRuC). The main objective of this study is to investigate the effect of steel fibres (manufactured and/or recycled fibres) on the fresh and mechanical properties of rubberised concrete (RuC) comprising waste tyre rubber (WTR). Free shrinkage is also examined. The main parameters investigated through ten different mixes are WTR and fibre contents. The results show that the addition of fibres in RuC mixes with WTR replacement substantially mitigates the loss in flexural strength due to the rubber content (from 50% to 9.6% loss, compared to conventional concrete). The use of fibres in RuC can also enable the development of sufficient flexural strength and enhance strain capacity and post-peak energy absorption behaviour, thus making SFRRuC an ideal alternative construction material for flexible pavements

Ir(III) Diamine Transfer Hydrogenation Catalysts in Cancer Cells

The development of catalytic metallodrugs is an emerging field that may offer new approaches to cancer chemotherapeutic design. By exploiting the unique properties of transition metal complexes, in‐cell catalysis can be applied to modulate the cellular redox balance as part of a multi‐targeting mechanism of action. We describe the synthesis and characterization of six coordinatively unsaturated iridium(III) diamine catalysts that are stable at physiological pH in aqueous solution. Reduction of the colorimetric substrate 2,6‐dichlorophenolindophenol by transfer hydrogenation under biologically compatible conditions achieved turnover frequencies up to 63 ± 2 h−1 and demonstrated that the source of hydride (sodium formate) is the limiting reagent, despite being in a 1000‐fold excess of the catalyst. The catalyst showed low in vivo acute toxicity in zebrafish embryos and modest in vitro potency towards cancer cells. When administered alone, the catalyst generated oxidative stress in cells (an effect that was conserved in vivo), but co‐treatment with a nontoxic dose of sodium formate negated this effect. Co‐treatment with sodium formate significantly enhanced catalyst potency in cancer cells (A2780 ovarian and MCF7 breast cancer cells) and drug‐resistant cells (A2780cis and MCF7‐TAMR1) but not in non‐tumorigenic cells (MRC5), demonstrating that a redox‐targeting mechanism may generate selectivity for cancer cells

Plasmon resonances of highly doped two-dimensional MoS2

The exhibition of plasmon resonances in two-dimensional (2D) semiconductor compounds is desirable for many applications. Here, by electrochemically intercalating lithium into 2D molybdenum disulfide (MoS2) nanoflakes, plasmon resonances in the visible and near UV wavelength ranges are achieved. These plasmon resonances are controlled by the high doping level of the nanoflakes after the intercalation, producing two distinct resonance peak areas based on the crystal arrangements. The system is also benchmarked for biosensing using bovine serum albumin. This work provides a foundation for developing future 2D MoS2 based biological and optical units

High-performance field effect transistors using electronic inks of 2D molybdenum oxide nanoflakes

Planar 2D materials are possibly the ideal channel candidates for future field effect transistors (FETs), due to their unique electronic properties. However, the performance of FETs based on 2D materials is yet to exceed those of conventional silicon based devices. Here, a 2D channel thin film made from liquid phase exfoliated molybdenum oxide nanoflake inks with highly controllable substoichiometric levels is presented. The ability to induce oxygen vacancies by solar light irradiation in an aqueous environment allows the tuning of electronic properties in 2D substoichiometric molybdenum oxides (MoO3-x). The highest mobility is found to be approximate to 600 cm(2) V-1 s(-1) with an estimated free electron concentration of approximate to 1.6 x 10(21) cm(-3) and an optimal I-On/I-Off ratio of >10(5) for the FETs made of 2D flakes irradiated for 30 min (x = 0.042). These values are significant and represent a real opportunity to realize the next generation of tunable electronic devices using electronic inks

The recurrent missense mutation p.(Arg367Trp) in YARS1 causes a distinct neurodevelopmental phenotype

Abstract: Pathogenic variants in aminoacyl-tRNA synthetases (ARS1) cause a diverse spectrum of autosomal recessive disorders. Tyrosyl tRNA synthetase (TyrRS) is encoded by YARS1 (cytosolic, OMIM*603,623) and is responsible of coupling tyrosine to its specific tRNA. Next to the enzymatic domain, TyrRS has two additional functional domains (N-Terminal TyrRSMini and C-terminal EMAP-II-like domain) which confer cytokine-like functions. Mutations in YARS1 have been associated with autosomal-dominant Charcot-Marie-Tooth (CMT) neuropathy type C and a heterogenous group of autosomal recessive, multisystem diseases. We identified 12 individuals from 6 families with the recurrent homozygous missense variant c.1099C > T;p.(Arg367Trp) (NM_003680.3) in YARS1. This variant causes a multisystem disorder with developmental delay, microcephaly, failure to thrive, short stature, muscular hypotonia, ataxia, brain anomalies, microcytic anemia, hepatomegaly, and hypothyroidism. In silico analyses show that the p.(Arg367Trp) does not affect the catalytic domain responsible of enzymatic coupling, but destabilizes the cytokine-like C-terminal domain. The phenotype associated with p.(Arg367Trp) is distinct from the other biallelic pathogenic variants that reside in different functional domains of TyrRS which all show some common, but also divergent clinical signs [(e.g., p.(Phe269Ser)—retinal anomalies, p.(Pro213Leu)/p.(Gly525Arg)—mild ID, p.(Pro167Thr)—high fatality)]. The diverse clinical spectrum of ARS1-associated disorders is related to mutations affecting the various non-canonical domains of ARS1, and impaired protein translation is likely not the exclusive disease-causing mechanism of YARS1- and ARS1-associated neurodevelopmental disorders. Key messages: The missense variant p.(Arg367Trp) in YARS1 causes a distinct multisystem disorder.p.(Arg367Trp) affects a non-canonical domain with cytokine-like functions.Phenotypic heterogeneity associates with the different affected YARS1 domains.Impaired protein translation is likely not the exclusive mechanism of ARS1-associated disorders