The photochemical stability of oil from Evening Primrose seeds

Photochemical reactions taking place in oil to which was added chlorophyll a as well as β-carotene and subjected to illumination for different times, have been investigated by measuring the absorption, fluorescence emission and fluorescence excitation spectra. The addition of carotene was found to greatly lower chlorophyll degradation as a result of the quenching of chlorophyll triplet states; however, its presence also influence the generation of other oil photoproducts. A comparison of the photoreactions induced by the light absorbed predominantly by chlorophyll-like pigments with those induced by bright light covering practically the whole visible region implies that the majority of the photoreactions occur with the participation of excited chlorophyll molecules.

The singlet excitation energy of β-carotene is not transferred to chlorophyll. The quenching of photochemically active triplets of chlorophyll alters the extent of oil degradation imparted by this excitation. The absorption and emission spectra of the oil degradation products are superimposable and, therefore, the quantitative analysis of the products is not easy. The generation of malonic dialdehyde, which is the main product of oil degradation, is a little slower in the presence of carotenoids, which suggests that some components within the oil protect against photooxidation by the addition of carotenoids.     

The effect of copper ions on interaction of UV radiation with methacrylic matrix – EPR study

The role of metal ions introduced to polymer matrix in the photochemical degradation of material is not fully understood. In this paper, we considered the effect of copper ions on the photochemical changes in Methafilcon A after UV-irradiation. The presence of methacrylic acid in the structure of Methafilcon A increases the loading capacity of these ions. In result, there is observed the production much more radicals after UV-irradiation than in pure matrix, without copper ions. When the time of UV-exposure increases, the EPR signal of trapped Cu(II) ions in the material decreases. This proves the transformation of Cu(II) to a diamagnetic state of stable Cu(I)-intermediates or copper oxides. Simultaneously, in the first 5-min of UV-irradiation there is observed a rapid increase in intensity of the radical signal, which disappears when the exposure time is extended. This mechanism of radical generating is quite different than for Methafilcon A matrix without copper ions.     

Impact of fat types on the rheological and textural properties of gluten-free oat dough and cookie

This study investigated the effect of six fats (margarine, butter, lard-LAR, refined palm oil-RPO, refined palm oil with stearin-RPOS, hydrogenated palm oil-HPO) with different solid fat content (SFC) on gluten-free oat dough and cookie properties. RPOS and HPO had the highest SFC. RPO dough was the softest, whereas HPO was the hardest one. Dough hardness was correlated with SFC (r = 0.87). Dough stickiness was positively correlated with dough hardness (r = 0.92). Dough hardness influenced the breaking force of the cookies (r = 0.79). HPO were the hardest cookies. Oscillatory test revealed that HPO dough was the stiffest as well as presented a higher rigidity compared to the other samples as showed by the creep tests. LAR cookies were the darkest, while HPO were the lightest. SFC of fats is the most important composition parameter which influences thermal, textural and rheological properties of the oat dough.     

Laser-induced heterometallic phase deposition from solutions of supramolecular complexes

Heterometallic (Au–Cu) phase precipitation on the surface of soda-lime glass as a result of laser-induced chemical liquid phase deposition (LCLD) is demonstrated for the first time. The precipitation of heterometallic structures was carried out under Ar⁺ laser irradiation from the solutions of supramolecular complexes. Energy dispersive X-ray (EDX) analysis showed that the deposits consist of both Au and Cu. Morphology of the deposited structures was found to be dependent on the used solvents: delocalized sparse surface structures in the case of the dichloromethane solution, close packed nanoparticles for the dimethyl formamide and homogeneous phase with nano-pores for the acetone solution. In accordance to the SEM photos and scan EDX analysis the homogeneous heterometallic phase with fixed Au/Cu ratio was achieved for the acetone solution of supramolecular complex. The observed formation of the heterometallic phase was explained by the laser-initiated intramolecular reduction process of the supramolecular metal core.     

Microwave-assisted preparation and characterization of nanoscale rhenium diboride

A simple and efficient microwave-assisted preparation of ReB₂-based material is reported utilizing ammonium perrhenate (NH₄ReO₄), magnesium boride (MgB₁₂) reactants and carbon as an absorber of microwave irradiation. The investigation of microwave irradiated NH₄ReO₄ +MgB₁₂ +C mixtures, thermal analysis results and electron microscopy examination reveals that NH₄ReO₄ decomposition produces ReO₃ at early stages of the process. The ReO₃ then exothermically reacts with MgB₁₂ forming the nanoscale Re₃B phase, which converts into ReB₂ upon further irradiation. The coupling of microwave energy with exothermic reactions significantly accelerates the formation of ReB₂. The product primarily consists of ReB₂ as well as B₄C and minor carbon phases. Structural characterization reveals that the average particle size of ReB₂ is ~ 50?nm.     

Tunable shapes in supported metal nanoparticles: From nanoflowers to nanocubes

The facile preparation of a range of supported nanoparticles on porous materials was successfully accomplished through the use of a range of environmentally friendly protocols including a modified impregnation/reduction methodology, ultrasounds and microwave irradiation. Materials were characterised by transmission electron microscopy (TEM) and XPS. Different morphologies including conventional nanospheres, nanoflower aggregates, nanorod-like structures and nanocubes were achieved under different conditions. The reported supported nanoparticles are envisaged to have interesting applications in various areas including catalysis, optics and sensors.     

Morphological changes and covalent reactivity assessment of single-layer graphene oxides under carboxylic group-targeted chemistry

Acid–base titrations were used to assess the covalent reactivity of carboxylic groups on single-layer graphene oxides (SLGO) or hydrazine-reduced analogues (SLGR) when treated with thionyl chloride and subsequent coupling to amines. Reflux with aggressive solvents led to size reduction and folding of individual sheets as well as loss of carboxylic groups, substantially so for SLGR. Room temperature treatment of SLGO with a carbodiimide collapsed the sheets into star-like clusters, which exhibited poor subsequent reactivity with amines. Ultimately, conventional chemical treatment of carboxylic groups on SLGO leads to morphological changes and reduced reactivity, which may potentially limit their use.     

Column Selection for Biomedical Analysis Supported by Column Classification Based on Four Test Parameters

This article focuses on correlating the column classification obtained from the method created at the Katholieke Universiteit Leuven (KUL), with the chromatographic resolution attained in biomedical separation. In the KUL system, each column is described with four parameters, which enables estimation of the F_KUL value characterising similarity of those parameters to the selected reference stationary phase. Thus, a ranking list based on the F_KUL value can be calculated for the chosen reference column, then correlated with the results of the column performance test. In this study, the column performance test was based on analysis of moclobemide and its two metabolites in human plasma by liquid chromatography (LC), using 18 columns. The comparative study was performed using traditional correlation of the F_KUL values with the retention parameters of the analytes describing the column performance test. In order to deepen the comparative assessment of both data sets, factor analysis (FA) was also used. The obtained results indicated that the stationary phase classes, closely related according to the KUL method, yielded comparable separation for the target substances. Therefore, the column ranking system based on the F_KUL-values could be considered supportive in the choice of the appropriate column for biomedical analysis.     

Trees in sacral and utilitarian practice: the value of nature and ecology in the life of the Selkups

The study represents an interdisciplinary analysis of the material and symbolic nature of the trees in the culture of Siberian indigenous people. The work is based on the archaeological, ethnographic and linguistic materials related to one of the Siberian aboriginal peoples, the Selkups. The results of the linguistic study of mythology, ethnographic research and archaeological excavations of the burial sites (16th–17th) allowed us to build up a model of the Selkup attitude to the most important elements of nature, in their view, the tree. To make a comparative analysis, the work considers the materials related to the neighbouring ethnic groups that were similar in their culture and the worldview. The study discusses the problem of continuing of the tradition in the period of 16th–20th centuries. Based on the structural analysis of the gathered materials, the authors came to the conclusion that the Selkup traditional perception of the trees remained unchanged within the discussed period. The continuation of the tradition allowed the Selkups to preserve the metaphysical perception of nature and their place in it. The close connection of man and nature became the basis for keeping the ecological balance and, as a result, protecting the society.