The PM19 protein : a functional analysis in Arabidopsis thaliana

The amino acid sequence of the trans-membrane protein, PM19, unique to the plant kingdom has been highly conserved over 450 million years of evolution in all plant genera including ferns and mosses, but is not found in aqueous plants such as algae. Thus, the function of this protein is possibly linked to the plant ability to grow on land. We have investigated the PM19 protein using a number of molecular biological tools in Arabidopsis thaliana. Gene expression studies using bioinformatics, northern blotting and promoter-GUS fusions show that the AtPM19 gene is highly expressed in seeds and seedlings, in addition to expression observed in leaves under drought stress. A translational fusion with GFP reveals that the protein is located in the plasma membrane. T-DNA insertion mutants have a germination phenotype; the mutant is more sensitive to high levels of salts in the medium, and in addition, the mutant has a lower stomatal conductance indicative of reduced guard cell turgor. The predicted secondary structure of the protein and the mutant phenotype suggest that PM19 may be a cation transporter and this is being tested by functional complementation of yeast mutants

Towards the development of a problem solver for the monitoring and control of instrumentation in a grid environment

This paper considers the issues involved in developing a generic problem solver to be used within a grid environment for the monitoring and control of instrumentation. The specific feature of such an environment is that the type of data to be processed, as well as the problem, is not always known in advance. Therefore, it is necessary to develop a problem solver architecture that addresses this issue. We propose to analyze the performance of the problem solving algorithms available within the WEKA toolkit and determine a decision tree of the best performing algorithm for a given type of data. For this purpose the algorithms have been tested using 51 datasets either drawn from publicly available repositories or generated in a grid-enabled environmen

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

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

A comprehensive study on optical features, gamma photon buildup factors and neutron shielding capability of B2O3-SB2O3-LI2O-BI2O3 glasses

ABSTRACT. Linear, nonlinear optical properties, photon buildup factors, and neutron shielding capability of glasses with chemical composition (65-x)B2O3-10Sb2O3-25Li2O-xBi2O3, where x = 0 (BSLB0) – 20 (BSLB20) mol% with steps of 4 mol% were examined. Molar refractivity (Rmolar) and molar polarizability (αmolar) were increased as Bi2O3 content mol% increase in the examined BSLB-glasses. The values of metallization criterion (Mcriterion) confirmed that the BSLB-glasses were non-metallic materials. The static (εstatic) and optical (εoptical) dielectric constants having the same trend of the refractive index (noptical). Values of optical electronegativity (χ*) were reduced from 0.825 for BSLB0 (Bi2O3 = 0 mol%) glasses to 0.758 for BSLB20 (Bi2O3 = 20 mol%) glasses. The linear electric/dielectric susceptibility (χ(1)) increased from 0.370 to 0.397. The nonlinear optical susceptibility (χ3) and nonlinear refractive index n2optical were enhanced by increasing Bi2O3 content in the BSLB-glasses. The BSLB20 glasses presented the least exposure and energy absorption build-up factors (EBF and EABF) at all considered thickness. BSLB20 sample achieved the best fast neutron removal cross section ( ) shield among all glasses. The total stopping powers (TSP) follows the trend (TSP)BSLB0 < (TSP)BSLB4 < (TSP)BSLB8 < (TSP)BSLB12 < (TSP)BSLB16 < (TSP)BSLB20. The electron absorbing and hence shielding capacity of the BSLB-glasses improves as their Bi2O3 content increase.     KEY WORDS: Antimony lithium-borate glasses, Optical properties, Buildup factors, Neutron shielding   Bull. Chem. Soc. Ethiop. 2022, 36(4), 949-962.                                                                DOI: https://dx.doi.org/10.4314/bcse.v36i4.19                                                     &nbsp

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

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

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

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