Analysis of the mathematical model of the gas bubbling curtain injection on the bottom and the walls of a continuous casting tundish

In the present work, the behaviour of a gas bubbling curtain (GBC) in the continuous casting tundish of industry is studied by using a physical model in the scale of 1:3. This study was made with the following configurations of gas injection inside the tundish: no gas injection, gas injection on the bottom and combined gas injection (CGI) on the bottom and the walls. Mathematical simulations were performed using the Eulerian approach. Mathematical modelling was also used to determine the residence time distribution curves (RTD curves). For the validation of the mathematical model, experiments were made using the physical models to obtain the homogenisation time of salt solutions. All of the results were validated by the experimental results of the RTD curves. The plug flow fraction remained almost constant when gas injection was used on the walls, however the mean residence time and the dead volume fraction, increased and decreased, respectively. The CGI on the bottom and walls allowed the entire cross-section to be covered with the GBC which acted as a barrier to the passage of inclusions.     

Sintering and Microwave Properties of Zirconium Tin Titanate Doped with Select Oxides

Zirconium tin titanate (ZST) is often used as a dielectric resonator for the fabrication of microwave devices. Pure compositions do not sinter easily by solid state sintering; therefore, sintering ZST requires sintering aids capable of creating defects that could improve diffusion processes and/or promote liquid phase sintering. The mechanisms by which the additives influence the microstructure and, consequently, the ZSTs dielectric properties are not very clear. The effects of ZnO, Bi₂O₃, and La₂O₃, on the stoichiometry and dielectric properties of ZST sintered at different temperatures were investigated in this study.     

Evaluation of the effect of heat input in superduplex stainless steel deposition by the plasma powder process*

Plasma powder surfacing is one of the latest processes for application of coatings, with control of dilution as its main feature. Surfacing with superduplex stainless steels is an interesting option for the construction and repair of equipment for applications in a highly corrosive environment, allowing the desired characteristics to be achieved: corrosion resistance and good mechanical properties. The aim of this work is to assess the ferrite content in the weld metal and the mechanical characteristics via microhardness profiles in surfacing of C-Mn steel pipes with deposition of UNS S32760 by plasma powder surfacing. Welding operations were carried out on pipes with deposition of SDSS, employing three welding heat input levels, varying the welding speed or the welding current. Then the geometry was analysed, the ferrite content in the weld metal was quantified and the microhardness profile was recorded. Variation in welding heat input caused changes in weld bead geometry, with variation in the welding current producing the most significant changes. Increase in heat input caused decrease in ferrite content of the weld metal. Regarding microhardness, only the condition with a higher level of welding current gave sufficiently high levels of microhardness in the weld metal.     

Increases in nitrogen use efficiency decrease nitrous oxide emissions but can penalize yield in sugarcane

Nutrient Cycling in Agroecosystems - Nitrogen (N) fertilization strategies focused on increasing nitrogen use efficiency (NUE) and decreasing nitrous oxide (N2O) emissions are important for...     

Conversion of aqueous extracts from thermochemical treatment of bagasse into functional emulsifiers

Synthetic emulsifiers in food industries are being replaced with a customer-friendly food ingredient that is derived from biomass using sustainable green technologies. After hydrothermal liquefaction treatment, raw bagasse (21%), pith (26%), and rind portions (25%) were obtained with reduced ash contents. As aqueous extracts, with oligosaccharides and lignin residues, it was used in the preparation of oil-in-water emulsions with 5% soybean oil. Results showed that the emulsions stabilised the oil droplets with particle size between 11 and 17 µm by steric repulsion with raw bagasse-stabilised emulsion showing a better stability at 25 °C (31 days). It was demonstrated that raw bagasse extracts, without alteration, maybe a potential unconventional source for food-grade emulsifiers by integrating a versatile thermochemical conversion of waste without the use of chemicals.     

Metagenomic analysis revealed the individualized shift in ileal microbiome of neonatal calves in response to delaying the first colostrum feeding

The aim of this study was to explore the effect of colostrum feeding time on the ileal microbiome of neonatal calves. In this study, 22 male Holstein calves were randomly assigned to different colostrum feeding time treatments: after birth (at 45 min, n = 7); at 6 h after birth (n = 8); and at 12 h after birth (TRT12h; n = 7). At 51 h after birth, calves were killed and ileum digesta was collected for microbiome analysis using shotgun metagenomic sequencing. Bacteria, archaea, eukaryotes, and viruses were identified from the ileum microbiome. For the bacteriome, Firmicutes and Proteobacteria were the predominant phyla, and Escherichia, Streptococcus, Lactobacillus were the 3 most abundant genera. For the archaeal community, Euryarchaeota and Crenarchaeota were the 2 major phyla, and Methanosarcina, Methanobrevibacter, and Methanocorpusculum were the 3 most abundant genera. In total, 116 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were identified from the ileal microbiome, with “biosynthesis of vancomycin group antibiotics,” “biosynthesis of ansamycins,” “valine, leucine, and isoleucine biosynthesis,” “ribosome,” and “d-alanine metabolism” as the top 5 functions. When the ileal microbiomes were compared among the 3 treatments, the relative abundance of Enterococcus was higher in TRT12h calves, suggesting that calves may have a higher abundance of opportunistic pathogens when the feeding of colostrum is delayed for 12 h. Moreover, among all KEGG pathways, the enriched “taurine and hypotaurine metabolism” (KO00430) pathway was identified in the ileal microbiome of TRT12h calves; however, future studies are needed to understand the effect on the host. Additionally, 2 distinct ileal microbial profiles were identified across all samples, indicating that that host factors may play a significant role in driving varied microbiome changes in response to colostrum feeding time. Whether such microbiome shifts affect long-term gut function and calf performance warrants future studies.     

Methodology for WEEE assessment in Algeria

Waste electrical and electronic equipment (WEEE) generated in emerging countries is increasing. This study presents a methodology to improve assessment and monitoring WEEE in Algeria. The proposed methodology is a two-step approach. The first step is the collection and collation of existing data from different national and international sources. In the second step, different assessment and forecasting methods are applied. Forecasting methods were selected from those models which provided minimum error indices. The paper considers also the availability and reliability of data in order to provide a future reliable assessment of WEEE in Algeria. The study revealed that the forecasting methods do not have a big influence on the results contrary to the inputs of the model.