Investigation of the effect of impurity of precursor materials on Si-doped boron carbide properties

Boron carbide is a notable ceramic, with its high hardness and low density. However, it suffers a sudden loss in strength under high shear stress. Doping boron carbide with Si/B is widely used to increase its resistance to amorphization. High purity boron and silicon hexaboride precursor powders are used for doping boron carbide, but these materials have high costs and supply chain constraints. This research investigated the effect of substituting lower purity B or using pure Si powder instead of SiB₆ on materials’ properties such as elastic and mechanical properties, microstructure, and amorphization resistances. It was observed that using lower-purity boron or pure Si powder instead of SiB₆ did not significantly affect critical properties, such as fracture toughness, hardness, or amorphization resistance. However, Young's modulus values decreased as B purity decreased and as Si was used instead of SiB₆. These findings demonstrate that substituting precursor materials in Si/B co-doped B₄C is possible with little change in the material's properties. This facilitates the use of easier-to-access, cheaper production routes to be used for silicon-doped boron carbide products.     

Suitability of Sodium Pyruvate as Decomposer of Carried-over Liquid Hydrogen Peroxide

The aim of the present study was to evaluate the concentration of sodium pyruvate in growth media by using the most-probable number method to decompose carried-over liquid hydrogen peroxide (H₂O₂) without negative influences on correct enumeration of Geobacillus stearothermophilus spores. An equivalent molar ratio of sodium pyruvate and H₂O₂ was verified to be sufficient for a complete decomposition. The results showed that by exposition of G. stearothermophilus spores in different liquid hydrogen peroxide and by carry-over of concentrations ranging from 3.56 · 10⁻⁶ up to 1.69 · 10⁻⁴ mol, a sodium pyruvate concentration of 0.05 mol L⁻¹ in growth media was most efficient for the recovery of spores.     

Template-Directed Incorporation of Functional Molecules into DNA

We report a versatile method for the incorporation of functional molecules into oligonucleotides carrying reactive groups by using a template-directed postsynthetic approach in the solution phase. For this purpose, we prepared oligonucleotides carrying an amino group on the backbone by using an acylic threoninol scaffold. The resulting oligonucleotides could be used to introduce almost any molecule carrying aldehyde, which can be, among other things, a metal-binding ligand or a fluorophore. In our study, we incorporated aldehyde-bearing phenanthroline, a metal-binding ligand, into oligonucleotides by template-directed reversible conjugation. We observed that the use of an abasic sugar site instead of a natural nucleobase in the template strand increased the yield of conjugation and induced selective incorporation of the phenanthroline. This method could lead progress in the development of probes for the recognition of abasic regions in duplex DNA. Moreover, template-directed formation of metal ligand-oligonucleotide conjugates might have potential applications in hybrid biocatalysis for enantioselective transformations.     

Influence of glycerol and water activity on the properties of compressed egg white-based bioplastics

In this paper, the effects of glycerol (35%, 40% and 45%) and water activity (0.34 and 0.48) on the physical, mechanical and morphological properties of compressed egg white-based bioplastics are investigated. Lighter, more reddish and less yellowish sheets with a decreased thickness and second-order transition temperature, improved mechanical properties (increased flexibility and decreased rigidity and stiffness) and constant moisture content can be obtained by increasing water activity. Increasing the GLY content results in the same type of changes but to a lesser extent and increased moisture content. Increasing both, water activity and GLY, leads to a more pronounced effect for some properties. This study demonstrates that compressed egg white-based bioplastics with desired properties can be obtained by adjusting water activity and GLY content during their synthesis.     

Shear amplification of orientation in Nylon 11/clay nanocomposites during melt casting and resulting electrical properties

In this study, the effect of organically modified clay on the orientation enhancement in Nylon 11 in melt casting was investigated. Nylon 11 was mixed with 1 and 3 wt% Cloisite 20A using twin screw extrusion and they were cast into films with varying take-up speeds. The addition of clay in Nylon 11 helped increase orientation levels substantially in melt cast films, both as a function of clay concentration as well as take-up speeds. This was primarily due to shear amplification effect caused by the movement of adjacent clay nanoparticles due to the shear flow gradient within the die. At low clay concentrations, the sub-T_m stretchability, and electrical breakdown strength improve as the presence of clay reduces inter/intrachain hydrogen bonding. At higher clay concentrations, both orientation and electrical breakdown levels decrease. The latter is primarily caused by increased percolation path of charge carriers. Nevertheless, clay nanoplatelets were very effective in their role as melt processing aids, as they enhance orientation levels of Nylon 11 thin films by shear amplification effect where they increase local chain orientation of chains trapped between clay platelets while their orientation relaxation is suppressed.     

The effects of heat treatment temperatures on photocatalytic activity of cobalt ferrite nanoparticles synthesised by microwave-assisted combustion method

In this study, the effects on the photocatalytic activities of particles after heat treatment has been applied to cobalt ferrite nanoparticles produced by microwave-assisted combustion method were observed. The heat treatment applied to the samples was produced with only the microwave effect, at temperatures ranging from 300 to 1000°C. Thermogravimetric analysis was performed on the precursor sample in air atmosphere. During this analysis, the gases released up to 1200°C were identified with a Fourier-transform infrared (FTIR) spectrometer integrated into a thermogravimetric analysis system. Then, the cobalt ferrite nanoparticles produced with heat treatments applied at various temperatures were used as a photocatalyst to remove the dyestuff content in synthetic wastewaters prepared by using Astrazon Red GTL textile dye by photocatalytic oxidation, and their photocatalytic activities were compared. In these experiments, the operational parameters for photocatalysis processes were applied as 400 rpm for stirring speed, 50 mg/L for initial contaminant concentration, 0.5 g/L for catalyst dosage, 25°C for temperature, and 4400 μW/cm² for light intensity. As a result of the experiments, it was observed that the crystal structure of the cobalt ferrite nanoparticles produced with the increase of the applied heat treatment temperature improved significantly. The obtained data show a strong relationship between the structural properties of materials and their photocatalytic activities. In addition, it was determined that the dyestuff in the solution was completely degraded in the experiments, and it was determined that all processes were compatible with the pseudo-first-order kinetic model.     

Investigation and feed-forward neural network-based estimation of dyeing properties of air plasma treated wool fabric dyed with natural dye obtained from Hibiscus sabdariffa

In the colouring processes of textile products, more environmentally friendly chemicals and finishing methods should be used instead of conventional ones that harm the environment every day, so that alternative realistic ways to protect nature, both academically and industrially, could be possible. Due to some inconveniences caused by synthetic dyes that are widely used today, in this study, ultrasonic dyeing of wool fabric with Hibiscus sabdariffa was carried out after environmental-friendly air vacuum plasma application which increased the absorption of the dyes into the textile material. According to the performance results, colour strengths of the wool fabrics were increased significantly. Surface morphology analysis was carried out and etching effects of air vacuum plasma treatment were clearly seen on the micrographs of the treated wool fabrics. An environmental-friendly green process was achieved through this study and it was concluded that vacuum air plasma treatment could be an alternative green-process as a pretreatment to increase the dye up-take of natural dyeing treatment. Moreover, in this study, a feed-forward neural network (FFNN) model was presented and used for predicting the dyeing properties (L, a, b and K/S) of samples. The experimental results showed that the presented model achieves the regression values greater than 0.9 for all dyeing properties. Consequently, it was considered that the proposed FFNN was successfully modelled and could be efficiently utilised for dyeing characteristics of wool fabrics dyed with natural dye extracted from Hibiscus sabdariffa.     

Comparison of the effects of oven- and microwave-roasting on the physicochemical properties and bioactive compounds of tomato seeds and oils

The tomato processing industry generates a significant amount of a by-product (pomace), which is a mixture of peels and seeds. The purpose of this study was to compare the effects of conventional oven-roasting (at 120°C, 150°C, and 180°C for 25 min) and innovative microwave-roasting (at 240, 388, and 536 W for 3 min) pretreatments on the physicochemical properties, fatty acid profiles, bioactive contents, and aroma profiles of tomato seeds and their hexane-extracted oils. The total flavonoids contents (TFCs) of the seeds decreased from 258.40 to 141.20 mg quercetin equivalent (QE) per kg after roasting. All roasting treatments improved the extractability of both α- and γ-tocopherols. The amounts of total tocopherols in the seeds increased from 917.61 to 1256.25 mg kg^–1 after pretreatment. Luteolin was found to be the most abundant phenolic in seed oils, increasing from 10.68 to 91.72 mg kg^–1, followed by quercetin, ferulic acid, and catechin. Within each roasting technique, the ones treated at 150°C and 338 W yielded the oils with the highest concentrations of aroma compounds, 418 and 92 mg kg^–1, respectively. The detrimental effect of microwave-roasting on these compounds was more pronounced. In conclusion, microwave-roasting at shorter times than conventional roasting produced tomato seed oils with well-preserved bioactive components and few unfavorable changes. Industrial relevance: Conventional oven-roasting has been widely applied to oilseeds to improve oil yield as well as to obtain desirable sensory characteristics of extracted oils for years. However, longer roasting times may also cause detrimental changes in the properties of oils. On the other side, microwave-assisted applications as an emerging technology provide homogenous and well-controlled heat distribution, shorter treatment times, and considerable energy savings for the processing of various foods. Microwave technology has been easily scaled up and is currently employed for sterilization, drying, pasteurization, precooking, and extraction by the food and chemistry industries. Therefore, the present research suggests the use of microwaves for comparatively short roasting times to produce edible oils with enhanced physicochemical attributes and bioactives contents, and well-maintained sensory properties. This promising innovative technology has the potential to be industrialized for a cost-effective seed roasting process.