Phase Equilibria Studies of the Cu-Fe-O-Si System in Equilibrium with Air and with Metallic Copper

Phase equilibria of the Cu-Fe-O-Si system have been investigated in equilibrium: (1) with air atmosphere at temperatures between 1373?K and 1673?K (1100?°C and 1400?°C) and (2) with metallic copper at temperatures between 1373?K and 1573?K (1100?°C and 1300?°C). High-temperature equilibration/quenching/electron-probe X-ray microanalysis (EPMA) techniques have been used to accurately determine the compositions of the phases in equilibrium in the system. The new experimental results are presented in the form of ??Cu₂O??-??Fe₂O₃??-SiO₂ ternary sections. The relationships between the activity of CuO_0.5(l) and the composition of slag in equilibrium with metallic copper are discussed. The phase equilibria information of the Cu-Fe-O-Si system is of practical importance for industrial copper production processes and for the improvement of the existing thermodynamic database of copper-containing slag systems.     

The relationship between milking interval and somatic cell count in automatic milking systems

The aim of this study was to explore whether, during automatic milking, milking interval or its variation is related to somatic cell count (SCC), even when corrected for effects of production, lactation stage, and parity. Data on milking interval and production level were available from the automatic milking systems of 151 farms. Data on SCC, parity, and lactation stage were derived from dairy herd improvement records of the same farms. Mainly due to incomplete records, data of 100 farms were used in the final analysis. For every cow, only 1 test day was used in the final analysis. Milking interval, the coefficient of variation of milking interval, production rate, the difference in production rate between short- and long-term, parity, days in milk, and some biologically relevant interactions were used in a linear mixed model with farm as random variable to assess their association with log10-transformed SCC. None of the interactions was significantly related to SCC, whereas all main effects were, and thus, stayed in the final model. The effect of milking interval was, although significant, not very strong, which shows that the effect of milking interval on SCC is marginal when corrected for the other variables. The variation in milking intervals was positively related with SCC, showing that the variation in milking interval is even more important than the milking interval itself. In the end, this study showed only a limited association between milking interval and SCC when milking with an automatic milking system.     

The energetics of helium and hydrogen atoms in β-SiC: an ab initio approach

Silicon carbide is a prime candidate for plasma-facing materials in future fusion reactors. The formation energies of various interstitial configurations of helium and hydrogen atoms in β-SiC were estimated based on density functional theory. Special consideration was given to the helium and hydrogen interstitials as the bubble seeds in β-SiC. From an energetic point of view, only one helium atom could position itself into the tetrahedral sites. However, up to three hydrogen atoms could easily position themselves into the tetrahedral sites by forming a stable H₂ molecule or a 3H-trimer that was newly identified in this study. Based on the different behaviors of helium and hydrogen, an explanation is proposed for the experimental observations of bubble formation in irradiated β-SiC.     

Experimental Study of Ferrous Calcium Silicate Slags: Phase Equilibria at {text{P}}_{{{text{O}}_{2} }} Between 10?5?atm and 10?7?atm

Ferrous calcium silicate slags, whose principal components are “FeO _x ”-CaO-SiO₂, are widely used in copper smelting and converting operations. In the current study, high-temperature equilibration and rapid quenching techniques were used to study the phase equilibria of the ferrous calcium silicate slags. The compositions of phases in the slags were measured accurately using electron probe X-ray microanalysis (EPMA). The phase equilibria of the system have been characterized at oxygen partial pressures between 10⁻⁵ atm and 10⁻⁷ atm at selected temperatures between 1473 K and 1623 K (1200 °C and 1350 °C). The effects of oxygen partial pressure and temperature on the compositions of phases in the slags are presented.     

Contributions of TMAH Surfactant on Hierarchical Structures of PVA/Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>–TMAH Ferrogels by Using SAXS Instrument

The magnetic hydrogels combining polyvinyl-alcohol (PVA) and Fe₃O₄ (magnetite)–TMAH (tetra-methyl ammonium hydroxide) have been successfully fabricated via a Freezing-thawing route. The magnetite nanoparticles were prepared from iron sands by using coprecipitation method. The transmission electron microscopy image revealed that the magnetite nanoparticles with a reaction temperature of 30 °C had the average particle size of 12 nm in clusters of aggregation. The result was similar to the particle size obtained from X-ray diffraction data analyzed by Scherer equation. Furthermore, synchrotron small angle X-ray scattering data were analyzed by using two lognormal distributions to calculate the distribution of the individual magnetite particles. Meanwhile, Teubner-Strey and Beaucage models were employed to observe the distribution of magnetite particles coated by TMAH as a surfactant. The data analysis showed that the magnetite particles within the magnetic hydrogels formed aggregations with diameters of cluster particles in the range from 13.1 to 31.8 nm. Interestingly, the diameter of clusters particle increased from 13.1 to 31.8 nm along with the increasing concentration of ferrofluids from 1 to 15 wt%. This phenomenon was predicted to result from the effect of TMAH as a surface reactant agent that prevented the aggregation by coating the surface of the magnetite nanoparticles.     

Harnessing the Excellent Mechanical,Barrier and Antimicrobial Properties of Zinc Oxide (ZnO) to Improve the Performance of Starch-based Bioplastic

ABSTRACT

The inherent properties of starch which are poor mechanical properties and its hydrophilicity that leads to poor long-term water absorption, fostered the incorporation of additives into starch-based bioplastic to enhance its mechanical and barrier properties. Zinc oxide (ZnO) nanoparticle as a lightweight material that is biocompatible, nontoxic, cost-effective and exhibit strong antibacterial activity can be considered as nano reinforcement of starch-based bioplastic. The present work studied the reinforcing effect of ZnO on the physical, mechanical and antibacterial properties of starch-based bioplastic. Bioplastic was prepared by melt-mixing starch and glycerol (3:1, w/w) with ZnO (1%, 2%, 3%, 4% and 5%, w/w). Bioplastic density and water contact angle increased with the increase of ZnO concentration. Bioplastic with the addition of 4% ZnO showed the lowest moisture content of 3.45%. Moreover, the decomposition temperature of bioplastic with ZnO increased slightly which indicated the higher stability. Mechanical properties evaluation showed that bioplastic with addition of ZnO had higher tensile strength than that without ZnO where 4% ZnO exhibited the highest tensile strength of 10.29 MPa with elongation of 5.69%. Cross-section microstructure after tensile test showed that ZnO was fairly dispersed in starch matrix that implied the increase of the mechanical properties of bioplastic. FTIR spectra exhibited that the intermolecular interaction in bioplastics occurred through C–H, C=O, C–O–H and O–H groups. In addition, biodegradability tests of bioplastic showed that the growth of microbes decreased in the presence of ZnO due to the nature of ZnO as an antibacterial compound. The results showed that ZnO played a key role in reinforcing the physical, mechanical and antibacterial properties of starch-based bioplastic.     

Preventing Antibiotic-Resistant Infections: Additively Manufactured Porous Ti6Al4V Biofunctionalized with Ag and Fe Nanoparticles

Implant-associated infections are highly challenging to treat, particularly with the emergence of multidrug-resistant microbials. Effective preventive action is desired to be at the implant site. Surface biofunctionalization of implants through Ag-doping has demonstrated potent antibacterial results. However, it may adversely affect bone regeneration at high doses. Benefiting from the potential synergistic effects, combining Ag with other antibacterial agents can substantially decrease the required Ag concentration. To date, no study has been performed on immobilizing both Ag and Fe nanoparticles (NPs) on the surface of additively manufactured porous titanium. We additively manufactured porous titanium and biofunctionalized its surface with plasma electrolytic oxidation using a Ca/P-based electrolyte containing Fe NPs, Ag NPs, and the combinations. The specimen’s surface morphology featured porous TiO₂ bearing Ag and Fe NPs. During immersion, Ag and Fe ions were released for up to 28 days. Antibacterial assays against methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa showed that the specimens containing Ag NPs and Ag/Fe NPs exhibit bactericidal activity. The Ag and Fe NPs worked synergistically, even when Ag was reduced by up to three times. The biofunctionalized scaffold reduced Ag and Fe NPs, improving preosteoblasts proliferation and Ca-sensing receptor activation. In conclusion, surface biofunctionalization of porous titanium with Ag and Fe NPs is a promising strategy to prevent implant-associated infections and allow bone regeneration and, therefore, should be developed for clinical application.     

Genome-Wide Scans and Transcriptomic Analyses Characterize Selective Changes as a Result of Chlorantraniliprole Resistance in Plutella xylostella

Pesticide resistance in insects is an example of adaptive evolution occurring in pest species and is driven by the artificial introduction of pesticides. The diamondback moth (DBM), Plutella xylostella (Lepidoptera: Plutellidae), has evolved resistance to various insecticides. Understanding the genetic changes underpinning the resistance to pesticides is necessary for the implementation of pest control measures. We sequenced the genome of six resistant and six susceptible DBM individuals separately and inferred the genomic regions of greatest divergence between strains using F_ST and θ_π. Among several genomic regions potentially related to insecticide resistance, CYP6B6-like was observed with significant divergence between the resistant and susceptible strains, with a missense mutation located near the substrate recognition site (SRS) and four SNPs in the promoter. To characterize the relative effects of directional selection via insecticide tolerance (‘strain’) as compared to acute exposure to insecticide (‘treatment’), four pairwise comparisons were carried out between libraries to determine the differentially expressed genes. Most resistance-related differentially expressed genes were identified from the comparison of the strains and enriched in pathways for exogenous detoxification including cytochrome P450 and the ABC transporter. Further confirmation came from the weighted gene co-expression network analysis, which indicated that genes in the significant module associated with chlorantraniliprole resistance were enriched in pathways for exogenous detoxification, and that CYP6B6-like represented a hub gene in the “darkred” module. Furthermore, RNAi knock-down of CYP6B6-like increases P. xylostella sensitivity to chlorantraniliprole. Our study thus provides a genetic foundation underlying selection for pesticide resistance and plausible mechanisms to explain fast evolved adaptation through genomic divergence and altered gene expression in insects.