Potassium-Promoted Carbon-Based Iron Catalyst for Ammonia Synthesis. Effect of Fe Dispersion

Potassium-promoted iron catalysts supported on thermally modified, partly graphitized carbon were studied in the ammonia synthesis reaction. Iron nitrate was used as a precursor of the active phase and KOH or KNO₃ were used as promoters. The kinetic studies of NH₃ synthesis were carried out in a differential reactor under 63 bar and 90 bar pressure. Hydrogen chemisorption, X-ray diffraction and transmission electron microscopy experiments were performed to determine the dispersion of iron in the specimens. All the K⁺–Fe/C catalysts proved to be sensitive to ammonia, the NH₃ partial pressure dependencies of their reaction rates being close to that of the commercial magnetite catalyst (KM I, H. Topsoe). The catalytic properties of the promoted Fe particles on carbon were shown to be dependent upon the iron dispersion, i.e. smaller particles exhibited higher turnover frequency in NH₃ synthesis. It is suggested that either small Fe crystallites expose more highly active sites, e.g. C-7 (B-5) or the promotion of small crystallites by the alkali is more efficient.     

Tocopherols,Tocotrienols and Carotenoids in Kernel Oils Recovered from 15 Apricot (<Emphasis Type="Italic">Prunus armeniaca</Emphasis> L.) Genotypes

We studied the content of tocopherols, tocotrienols and carotenoids in oil extracted from the kernels of 15 apricot (Prunus armeniaca L.) genotypes and the associated oil yield of the studied samples. The oil yield in apricot kernels was in a wide range of 27.2–61.4% (w/w) dry weight basis. For each class of studied compounds (tocochromanols and carotenoids), a three-fold difference was found between the lowest and the highest content (78.8–258.5 and 0.15–0.53 mg/100 g of oil, respectively). γ-Tocopherol accounted for 91–94% of total tocochromanols detected in all tested samples. Lutein, zeaxanthin, β-cryptoxanthin and β-carotene were the main compounds among the eight different carotenoids detected in apricot kernel oils; they comprised 76–94% of the total carotenoids content, and compositions were characteristic for specific genotypes. The oil yield and content of lipophilic antioxidants in apricot kernel oils were significantly affected by the genotype. The oil yield was negatively correlated with the total amount of tocochromanols (r = ?0.910) and carotenoids (r = ?0.704) in apricot kernel oils.     

The toxicity in vitro of titanium dioxide nanoparticles modified with noble metals on mammalian cells

The aim of the presented work was to evaluate the effect of modification of titanium dioxide nanoparticles with noble metals and their oxides on selected mammalian cells. The in vitro cytotoxicity studies of titanium dioxide (TiO₂) nanoparticles modified with Au, Ag, Pd, Ag₂O, and PdO with reference to the unmodified TiO₂ nanoparticles were presented. The evaluation of cytotoxic activity of the tested nanocomposite particles was carried out using three cell lines: Caco-2 colorectal epithelial adenocarcinoma cells, BJ normal human skin fibroblasts, and L929 mouse fibroblasts. The in vitro studies included determination of cell viability after 24 and 48 hours of exposure to the nanocomposite particles, using the MTT assay, as well as flow cytometry with Annexin V-FITC staining. Our results indicate that irrespectively of the kind of cell line and assay used, nanoparticles of unmodified titanium dioxide as well as those with addition of gold and palladium have a slight impact on cell viability at the investigated concentration range (10-200 μg/mL). Nanoparticles with addition of silver (Ag and Ag₂O), were found to have significantly higher toxic effect, the level of which varied depending on the cell line and assay used.     

Wood adhesives derived from hyperbranched polyglycerol cross-linked with hexamethoxymethyl melamines

Wood adhesive system based on hyperbranched polyglycerol cross-linked with hexamethoxymethyl melamines was described. The obtained results showed that it was possible to develop polyglycerol-based interior-grade adhesive exhibiting dry shear strengths of the joints exceeding that of the solid wood. Gelling times of the studied formulations were comparable to those of the industrial thermosetting systems (60–80 s at 100 °C). It was also found that wet shear strengths depended on functionality and F/Me molar ratio in the cross-linking resin.     

Assessment of aliphatic poly(ester-carbonate-urea-urethane)s potential as materials for biomedical application

Selected mechanical and biological properties of biodegradable elastomeric poly(ester-carbonate-urea-urethane)s (PECUUs) point towards their potential to be applied as scaffolds in tissue engineering. Here we explore their medical applicability taking into account their hemocompatibility and cytotoxicity. The influence of the ester monomer (derivatives of adipic and succinic acids), as well as diisocyanate type (IPDI and HDI) on the investigated PECUUs properties is presented. The presence of aliphatic diisocyanates, cyclic IPDI or linear HDI, governs the adhesion of Candida cells to these polymers offering the possibility to control the biofilm formation on their surface. In comparison to the linear form, cyclic diisocyanates with pentamethylene succinate or adipate fragments had two to three times lower biofilm mass formation on their surface. Reduced hemoglobin release from red blood cells observed during incubation of tested polymers with human erythrocytes suspension indicates their potential biocompatibility with human tissues. PECUUs were also able to support the growth of human keratinocytes HaCaT on their surface when coated with collagen. In effect, IPDI derivatives might possess a high potential for use in biomedical applications.     

Silicon-Boron Alloys as New Ultra-High Temperature Phase-Change Materials: Solid/Liquid State Interaction with the h-BN Composite

Silicon-boron alloys have been recently pointed out as novel ultra-high temperature phase change materials for applications in Latent Heat Thermal Energy S     

Gold(III) ions sorption on sulfur-containing polymeric sorbent based on 2,2‘-thiobisethanol dimethacrylate

ABSTRACT

Studies of gold(III) ions sorption from hydrochloric acid solutions on 2,2‘-thiobisethanol dimethacrylate/ethylene glycol dimethacrylate copolymer were performed. The correlation between the concentration of HCl (0.0001–4 M) and sorption efficiency (370–140 mg g^?1) was observed. The kinetics of sorption and the parameters of Langmuir and Freundlich isotherms for the studied systems were determined. The use of 0.8 M thiourea in 3 M HCl as eluent assured the high recovery degree of sorbed ions. It can, therefore, be concluded that newly synthesized sulfur-containing sorbent can be used in the recovery and concentration of gold(III) ions.     

Comparative Study of Sc(III) Sorption onto Carbon-based Materials

The sorption behavior of Sc(III) on different materials including activated carbon (AC), carbon nanotubes (CNTs), graphene oxide (GO), and the chelating resin Chelex 100 was investigated. In general, the sorption of scandium increases with increasing pH. For pH in the range from 2.5 to 5.5, the sorption of Sc(III) onto CNTs, GO, and Chelex 100 is quantitative, whereas a significantly lower amount of scandium ions was retained on AC. The specific amount of Sc(III) adsorbed at pH 2 attained 2.1, 2.9, 36.5, and 37.9 mg g^?1 for AC-COOH, Chelex 100, GO, and CNTs-COOH, respectively. At pH 4, a similar value was obtained for oxidized AC (2.2 mg g^?1), whereas the specific amount adsorbed significantly increased for Chelex (23.4 mg g^?1). The highest values were obtained for GO (39.7 mg g^?1) and oxidized CNTs (42.5 mg g^?1). Better kinetic retention was observed at pH 2 for CNTs and GO, whereas at pH 4 the kinetic behavior of Chelex 100, GO, and CNTs toward Sc(III) was comparable.     

Chemical Composition and Oxidative Stability of Selected Plant Oils

Scientific data on the oxidative stability of borage oil, Camelina sativa oil, linseed oil, evening primrose oil and pumpkin seed oil are scarce. Chemiluminescence (CL) methods most commonly used to determine the oxidative stability of oils include measurement of hydroperoxide, intensity of light emitted during the accelerated oxidation process performed at high (>100 °C) temperatures or assisted by forced flow of air/oxygen through the sample. The aim of this study was to investigate the chemical composition and oxidative stability of selected vegetable oils available on the Polish market. Oxidative stability was determined using a fast, novel chemiluminescence-based method, in which light emitted during oxidation process conducted at 70 °C in the presence of some catalyzing Fe²⁺ ions is measured. A reaction of the applied type has not been reported so far. High contents of tocopherols and phytosterols were found in the analyzed oil samples. Oxidative stability of the samples was in most cases higher than the stability of refined rapeseed oil, a relatively stable substance from the oxidation point of view.