Assessment of Cell Toxicity and Oxidation Catalytic Activity of Nanosized Zinc-doped Ceria UV Filter

The abundance of cerium in natural resources, its ability to absorb UV light while being transparent to visible light, as well as low photocatalytic activity make ceria (CeO2) a promising candidate for UV filter material in sunscreens. Doping with different elements can further decrease ceria catalytic and photocatalytic activity, thus preventing the degradation of other sunscreen ingredients. In this work, pure and zinc-doped ceria nanoparticles were prepared by a simple and environmentally benign hydrothermal synthesis, and characterized using various techniques. Fine ceria and doped ceria nanoparticles with particle sizes of 6.1±0.9 and 4.2±0.4 nm were prepared. In both samples, cubic ceria was the only crystalline phase, but the homogeneous distribution of zinc in the doped sample was confirmed by energy dispersive X-ray spectrometry. Nanoparticles exhibited transparency in the visible region and absorbance in the UV region with band gap of 3.23 to 3.14 eV for pure and doped sample, respectively. The oxidation stability time, determined through Castor oil oxidation process, was 23 hours for the pure and 15 hours for the doped sample, which is quite satisfactory. In vitro cytotoxicity study showed that the prepared nanoparticles were well tolerated by human skin keratinocytes (HaCaT cell line) with no significant differences in skin cells viability. However, further investigations on in vivo systems are necessary to reach a firm conclusion regarding the toxicity of ceria and doped ceria nanoparticles, and other potential dopants should be considered for improvement of ceria properties for sunscreen application. This work is licensed under a Creative Commons Attribution 4.0 International License

Uticaj azota na prinos zelene biomase i suve materije Sorghum sp. vrsta po fazama rastenja

The paper investigated the production properties of three sorghum genotypes: NS-Džin (forage sorghum), Zora (Sudan grass) and Siloking (interspecies hybrid) in terms of different nitrogen rates used in side dressing in 2009 and 2010. The subject of study was green biomass and dry matter yield in the stages of intensive growth and tasseling. The results have shown that there have been significant fluctuations in production indicators between the genotypes. In the total average, the lowest yield was recorded for the Sudan grass (85.41 t ha-1). Significantly higher yields were recorded for the interspecies hybrid (90.22 t ha-1) and the forage sorghum (93.51 t ha-1). Although the effect of nitrogen rates depended on weather conditions, i.e. rainfall distribution, the optimal nitrogen rate in both years was 180 kg ha-1.U radu su proučavane produktivne osobine tri genotipa sirka i to: NS-Džin (krmni sirak), Zora (sudanska trava) i Siloking (interspecijes hibrid) u zavisnosti od upotrebljenih količina azota za dopunsku ishranu biljaka tokom 2009. i 2010. godine. Ispitivani su prinos zelene mase u fazama intezivnog porasta i metličenja. Između ispitivanih genotipova postoje značajna variranja u pokazateljima produktivnosti. U ukupnom proseku najmanji prinos dala je sudanska trava 85,41 t ha-1. Značajno viši prinos bio je kod interspecijes hibrida (90,22 t ha-1) i krmnog sirka (93,51 t ha-1). Iako je efekat upotrebljenog azota zavisio od vremenskih uslova, odnosno od rasporeda padavina, u obe godine optimalna količina azota bila je 180 kg ha-1

Novel Ba-hexaferrite structural variations stabilized on the nanoscale as building blocks for epitaxial bi-magnetic hard/soft sandwiched maghemite/hexaferrite/maghemite nanoplatelets with out-of-plane easy axis and enhanced magnetization

Atomic-resolution scanning-transmission electron microscopy showed that barium hexaferrite (BHF) nanoplatelets display a distinct structure, which represents a novel structural variation of hexaferrites stabilized on the nanoscale. The structure can be presented in terms of two alternating structural blocks stacked across the nanoplatelet: a hexagonal (BaFeO) R block and a cubic (FeO) spinel S block. The structure of the BHF nanoplatelets comprises only two, or rarely three, R blocks and always terminates at the basal surfaces with the full S blocks. The structure of a vast majority of the nanoplatelets can be described with a SR∗S∗RS stacking order, corresponding to a BaFeO composition. The nanoplatelets display a large, uniaxial magnetic anisotropy with the easy axis perpendicular to the platelet, which is a crucial property enabling different novel applications based on aligning the nanoplatelets with applied magnetic fields. However, the BHF nanoplatelets exhibit a modest saturation magnetization, M, of just over 30 emu g. Given the cubic S block termination of the platelets, layers of maghemite, γ-FeO, (M), with a cubic spinel structure, can be easily grown epitaxially on the surfaces of the platelets, forming a sandwiched M/BHF/M platelet structure. The exchange-coupled composite nanoplatelets exhibit a remarkably uniform structure, with an enhanced M of more than 50 emu g while essentially maintaining the out-of-plane easy axis. The enhanced M could pave the way for their use in diverse platelet-based magnetic applications

Assessment of deep cryogenic heat-treatment impact on the microstructure and surface chemistry of austenitic stainless steel

This systematic study deals with the influence of deep cryogenic treatment (DCT) on microstructure and surface properties of austenitic stainless steel AISI 304 L on different length scales and in the surface region. The study incorporates different analysis techniques, such as light microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), electron backscatter diffraction (EBSD), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ions mass spectrometry (ToF-SIMS). DCT modifies the microstructure of treated samples through promoted precipitation of Cr7C3 carbides, induced twinning and α-martensite formation. Additionally, XPS/AR-XPS and ToF-SIMS results also provide evidence of modified oxidation dynamics of DCT samples compared to conventionally heat-treated samples with increase of the Fe-oxide fraction and lower Cr-oxide fraction in the surface oxide layer. An evaluation of oxidation states and ions distribution within the surface layer of deep cryogenically heat-treated stainless steel AISI 304 L is conducted with XPS/ToF-SIMS. These results are correlated with the microstructural changes and nitrogen diffusivity induced by DCT, which are associated with modified oxidation behaviour of AISI 304 L. These results provide further understanding of DCT dynamic on the overall microstructure and the corresponding surface behaviour

Hydrogen Evolution on Pyrolytic Graphite

The hydrogen evolution reaction from acid solutions was studied on highly oriented pyrolytic graphite at different surfaces obtained by cutting graphite under the various angles in respect to the basal plane. The experiments were done galvanostatically on the polished samples of desired orientation, in a cell which enabled the pretreatment of graphite at 1000° C in argon and use of prepurified Na2S04 + H2S04 solutions. Tafel lines with 2 RT/F slopes were obtained in all the experiments with i 0 varying from ca 10-9A/cm2 for cleavage plane to ca 10-8A/cm~ for edge plane. The transients show the considerable pseudo-capacitances of 250--500 μF/cm2 being larger at more negative potentials and edge surfaces. The experimental data are consistent with the slow discharge - electrochemical desorption mechanism with the limited number of sites of H adsorption but also with the coupled discharge - recombination reaction for hydrogen evolution

The effect of nitrogen fertilizer rates on green biomass and dry matter yield of Sorghum sp. at different growth stages

The paper investigated the production properties of three sorghum genotypes: NS-Džin (forage sorghum), Zora (Sudan grass) and Siloking (interspecies hybrid) in terms of different nitrogen rates used in side dressing in 2009 and 2010. The subject of study was green biomass and dry matter yield in the stages of intensive growth and tasseling. The results have shown that there have been significant fluctuations in production indicators between the genotypes. In the total average, the lowest yield was recorded for the Sudan grass (85.41 t ha-1). Significantly higher yields were recorded for the interspecies hybrid (90.22 t ha-1) and the forage sorghum (93.51 t ha-1). Although the effect of nitrogen rates depended on weather conditions, i.e. rainfall distribution, the optimal nitrogen rate in both years was 180 kg ha-1

Synchronizing inventory and transport within supply chain management

The problem considers synchronized optimization of inventory and transport, and focuses on producer-distributor relations. Particular attention is paid to developing a mathematical model and an optimization problem that can be used to minimize the overall distribution cost by an appropriate placement of warehouses and cross-docking points. Solutions to this problem are explored using genetic algorithms and ideas from graph/network theory. Note: there are three separate reports contained within the uploaded .pdf file

Robust and durable superlubricity enabled by carboxylated graphene quantum dots in lubricated steel contacts

Achieving macroscale superlubricity on engineering steel by utilizing aqueous green lubricants has gained growing interest, given its substantial potential to reduce energy consumption and carbon footprint. However, maintaining superlubricity under diverse sliding conditions over a prolonged duration is a major obstacle for real-scale applications. Herein, we report that a robust and durable tribofilm enabled by a unique lubrication mechanism based on carboxylated graphene quantum dots (CGQDs) in aqueous glycerol triggers macroscale superlubricity in self-mated steel contacts. A dedicated intermittent test was designed to show the superlubricity's robustness and the ability of the tribofilm to adapt to a variety of relevant sliding conditions. Moreover, the boundary film provides an average coefficient of friction of around 0.007 and up to 69 % wear reduction (compared to the base lubricant), resulting in the maintenance of superlubricity at a real final contact pressure of 123 MPa, which increases the upper limit of the contact pressure compared to current aqueous-lubricated steel contacts. The new superlubricity mechanism was enabled by the chemical adsorption of the CGQDs onto the worn metal surface, coupled with the tribo-induced structural degradation and transformation of the CGQDs into layered graphitic structures that generate an adaptable low-shear interface. This work provides new insights into the role of chemical adsorption and structural transformation of CGQDs in achieving superlubricity and is an important step forward for implementing energy-efficient and green lubrication technologies for industrial applications

Hydroxyapatite nanopowders prepared in the presence of zirconium ions

Hydroxyapatite nanopowders were prepared in the presence of different concentrations of zirconium ions. Such crystallization conditions yielded significantly reduced particle size and increased specific surface area. Cell viability and oxidative stress studies showed that biocompatibility was not impaired when compared to pure hydroxyapatite. Non-isothermal sintering implied the possibility for suppressing the reaction between hydroxyapatite and zirconia by limiting it to only calcium phosphates. Stress-induced transformation of tetragonal to monoclinic zirconia is facilitated by total hydroxyapatite to β-tricalcium phosphate phase transformation

GENOTYPE × YEAR INTERACTION ON RYE PRODUCTIVITY PARAMETERS CULTIVATED ON SANDY CHERNOZEM SOIL

Rye is a dual-purpose crop, for nutrition but also for bioenergy. The selection of rye is aimed at its improvement as a plant for human and animal consumption, but also it is interesting for bioenergy production as it combines high biomass production with low environmental impact. There is a growing demand for sustainable sources of biomass worldwide. Directions for achieving rye selection for energy purposes include selection to increase biomass yield and corresponding physiological properties. During three years (2019-2021), four rye genotypes were examined. The aim of this study was to examine the influence of genotype (G), year (Y) and their interaction (G×Y) on rye productivity parameters: plant height (PH), spike length (SL), 1000-grain weight (TGW), hectoliter mass (HM), green biomass yield (GBY), biogas yield (BGY) as well as the possibility of using rye as an alternative fuel. Rye is an excellent raw material for the production of healthy food, but also for the production of biofuels. The study discussed the potential use of four high yielding genotypes for biofuel production. Genotype G1 (25.29 t ha-1) had a statistically significantly higher average green biomass yield compared to genotypes G2, G3 and G4 (22.98 t ha-1, 23.56 t ha-1 and 23.76 t ha-1). Significant G×Y interactions demonstrate differences between rye genotypes in response to environmental conditions. Plant height was directly proportional to biomass yield. As one of the targets in breeding programs, to develop taller cultivars as biofuel feedstock. Screening and selection of appropriate rye varieties for each region is critical for optimum results. © 2022, Genetika. All Rights Reserved