Impact of Ag2O on the mechanical and shielding features of ZnO- Er2O3-TeO2 glasses

The investigation involves a comprehensive study on the mechanical and shielding features of the zinc erbium tellurite glasses as a function of doped Ag2O content. The mechanical features are estimated for the examined glasses by utilizing the Makishima-Makinzie model. The results showed the mechanical moduli of Young (E), bulk (B), Shear (K), and longitudinal (L) increased with the increment of the Ag2O substitution ratio. Besides, the radiation shielding properties were also studied and discussed. Among the shielding parameters, the linear attenuation coefficient (LAC), half-value layer (HVL), the lead equivalent and transmission rate (TR) were estimated. The linear attenuation coefficient results illustrated that the TZEAg glasses are better compared to the commercial marketing glasses, especially TZEAg5 glasses. Doping of Ag2O content in zinc erbium tellurite glass improves its ability to attenuate the gamma photons. Also, this study revealed the effectiveness of the examined glasses on the fast neutron, where the fast neutron mass removal cross-section ∑R (cm2/g) computed theoretically. The results offered the maximum value of ∑R = 0.019 cm2/g attained for TZEAg1 while the minimum value ∑R = 0.01884 cm2/g for TZEAg5 glass.

Structural, Optical, Magnetic and Photon Attenuation of Novel Potassium Lead Borate Glasses Doped with MnO

Potassium lead borate glasses doped with MnO (40B2O3+40PbO+(20-x)K2O+xMnO: x= 0-5 mol%) have been prepared via standard melting quenching process. The impact of MnO on the structure, optical, magnetic and gamma-ray protection properties of pottisium lead borate glasses have been examined. The density was increased from 4.83±0.01 to 5.23±0.01 g/cm3 as MnO content increased. The obtained direct optical gap (Eg) values were 2.84, 2.59, 2.41, 2.19, 1.95, and 1.84 eV for the Mn-x (x=0, 1, 2, 3, 4, and 5) glass samples, respectively. FTIR spectra demonstrated that as the MnO concentration increases in the glass network the intensity and width of the IR bands were increased. The magnetic measurement revealed that the magnetic situation (Ms) was decreased while the magnetic coercivity (Hc) was increased with increasing MnO substitution ratio. The linear attenuation coefficient of the follows the order: µMn-0 < µMn-1 < µMn-2 < µMn-3 < µMn-4 < µMn-5. Half value layer (HVL) rises as µ decreases and vice versa. The range of the HVL is 0.002 – 3.378, 0.002 – 3.334, 0.002 – 3.291, 0.002 – 3.248, 0.002 – 3.176, and 0.002 – 3.106 cm for Mn-x (x=0, 1, 2, 3, 4, and5). The trend of Zeff variation is related to that of both linear and mass attenuation coefficients (µ and µm). The produced Mn-glasses can be employed in a variety of optical, magnetic and radiation protective applications.

An Investigation on Substitution of Ag Atoms for Al or Ti Atoms in the Ti2AlC MAX Phase Ceramic Based on First-Principles Calculations

The present work introduced first-principles calculation to explore the substitution behavior of Ag atoms for Al or Ti atoms in the Ti2AlC MAX phase ceramic. The effect of Ag substitution on supercell parameter, bonding characteristic, and stability of the Ti2AlC was investigated. The results show that for the substitution of Ag for Al, the Al-Ti bond was replaced by a weaker Ti-Ag bond, decreasing the stability of the Ti2AlC. However, the electrical conductivity of the Ti2AlC was enhanced after the substitution because of the contribution of Ag 4d orbital electrons toward the density of states (DOS) at the Fermi level coupled with the filling of Ti d orbital electrons. For the substitution of Ag for Ti, new bonds, such as Ag-Al bond, Ag-C bond, Al-Al bond, Ti-Ti anti-bond, and C-C anti-bond were generated in the Ti2AlC. The Ti-Ti anti-bond was strengthened as well as the number of C-C anti-bond was increased with increasing the substitution ratio of Ag for Ti. Similar to the substitution of Ag for Al, the stability of the Ti2AlC also decreased because the original Al-Ti bond became weaker as well as the Ti-Ti and C-C anti-bonds were generated during the substitution of Ag for Ti. Comparing with the loss of Ti d orbital electrons, Ag 4d orbits contributed more electrons to the DOS at the Fermi level, improving the electrical conductivity of the Ti2AlC after substitution. Based on the calculation, the substitution limit of Ag for Al or Ti was determined. At last, the substitution behavior of Ag for Al or Ti was compared to discriminate that Ag atoms would tend to preferentially substitute for Ti atoms in Ti2AlC. The current work provides a new perspective to understand intrinsic structural characteristic and lattice stability of the Ti2AlC MAX phase ceramic.

Genome-wide identification of RING finger genes in flax (Linum usitatissimum) and analyses of their evolution

Background Flax (Linum usitatissimum) is an important crop for its seed oil and stem fiber. Really Interesting New Gene (RING) finger genes play essential roles in growth, development, and biotic and abiotic stress responses in plants. However, little is known about these genes in flax. Methods Here, we performed a systematic genome-wide analysis to identify RING finger genes in flax. Results We identified 587 RING domains in 574 proteins and classified them into RING-H2 (292), RING-HCa (181), RING-HCb (23), RING-v (53), RING-C2 (31), RING-D (2), RING-S/T (3), and RING-G (2). These proteins were further divided into 45 groups according to domain organization. These genes were located in 15 chromosomes and clustered into three clades according to their phylogenetic relationships. A total of 312 segmental duplicated gene pairs were inferred from 411 RING finger genes, indicating a major contribution of segmental duplications to the RING finger gene family expansion. The non-synonymous/synonymous substitution ratio of the segmentally duplicated gene pairs was less than 1, suggesting that the gene family was under negative selection since duplication. Further, most RING genes in flax were differentially expressed during seed development or in the shoot apex. This study provides useful information for further functional analysis of RING finger genes in flax and to develop gene-derived molecular markers in flax breeding.

Experimental Study of the Mechanical Behaviour of Brick Waste Concrete and Analytical Prediction of its Elastic Modulus as a Three-Phase Composite Material

This paper focuses on the characterization of the mechanical behaviour of concrete incorporating different percentages of brick waste aggregates (BWA). Compressive strength, splitting tensile strength and elastic modulus of this material were measured based on standard laboratory tests and its microstructure was characterized based on scanning electron microscope (SEM) observations. A decrease in these properties was observed with the increase of BWA substitution ratio. However, this decrease remains moderate up to a substitution percentage of 30% (about 12% for compressive strength and elastic modulus and 8% for splitting-tensile strength). In addition, an increase in the concrete porosity was observed with the increase of BWA substitution ratio, which can explain the decrease observed in the measured mechanical characteristics. SEM views on concrete incorporating 100% of BWA showed that the interfacial transition zone (ITZ) and the cement paste present a higher porosity when compared to those of the reference concrete made with natural aggregates.Finally, a micromechanical analytical homogenization model predicting the elastic modulus of brick waste concrete (BWC) according to its composition is proposed where BWC is modelled as a three-phase composite. A good agreement was found between analytical predictions and experimental results proving that BWC mechanical characteristics are mainly governed by BWA mechanical properties and their volume fraction within concrete.

Optimization of Alkali-Activated Municipal Slag Composite Performance by Substituting Varying Ratios of Fly Ash for Fine Aggregate

This study investigates the effect of varying ratios of fly ash as a partial replacement for fine aggregate on the performance of alkali-activated municipal slag composites. The strength and other properties of alkali-activated cementitious material (AACM) composites can be optimized by selecting the appropriate mix proportion. In this study, we used fly ash as a substitute for fine aggregate (FA/S) at varying ratios of 0.0, 5.0, 10.0, 15.0, 20.0, 25.0, and 30.0%, mixed with 50% water (W/SL), and 20% alkali activator (AL/SL) content instead of municipal slag (SL) as a core binder, cured in steam conditions. The effects of these substitutions on the initial mixing temperature, slump flow, compressive and splitting tensile strengths, and microstructure analysis of composites cured in steam conditions were investigated at 1, 7, 28, and 91 days. The evaluation of the experimental results revealed that increasing the ratio of fly ash substitution to fine aggregate by up to 20.0% led to a higher strength attributable to the composites, whereas when the extra substitution ratio of FA/S ranged from 25.0–30.0%, significant decreases in strength were observed. The composites’ strengths were estimated using the ACI 209 and ACI 318 design equations and compared to the measured strengths.