A method of concentration estimation of trienes,tetraenes, and pentaenes in evening primrose oil

There is no simple method available to estimate the concentration of conjugated fatty acids (CFA) with more than two double bonds in plant oils, because there are no commercially available complete sets of CFAs standards needed for such analysis. This paper presents such a method based on the absorption and fluorescence spectra of available CFAs standards and a computer program calculation. Using this method, the concentrations of the α‐eleostearic acid (conjugated trienoic acid (ELA) 8.8 × 10^?4 mol/L) and cis‐parinaric acid (conjugated tetraenoic acid (PnA) 3.5 × 10^?5 mol/L) in evening primrose oil were estimated. The accuracy of the calculation method is around 10%. Practical applications: This is the first report about the existence of CFAs in evening primrose oil. The described method estimates the total concentration of trienes, tetraenes, and pentaenes in evening primrose oils without using HPLC or other analytical methods. These CFAs are important from a health point of view. They are not synthesized by the human body. Therefore, plant oils containing these fatty acids (FA) are very valuable. Knowledge about the concentrations can be utilized to prepare a mixture of the plant oils with a favourable n‐3 to n‐6 FAs ratio and in addition containing CFAs.     

Fiber Specific Changes in Sphingolipid Metabolism in Skeletal Muscles of Hyperthyroid Rats

Thyroid hormones (T₃, T₄) are well known modulators of different cellular signals including the sphingomyelin pathway. However, studies regarding downstream effects of T₃ on sphingolipid metabolism in skeletal muscle are scarce. In the present work we sought to investigate the effects of hyperthyroidism on the activity of the key enzymes of ceramide metabolism as well as the content of fundamental sphingolipids. Based on fiber/metabolic differences, we chose three different skeletal muscles, with diverse fiber compositions: soleus (slow-twitch oxidative), red (fast-twitch oxidative-glycolytic) and white (fast-twitch glycolytic) section of gastrocnemius. We demonstrated that T₃ induced accumulation of sphinganine, ceramide, sphingosine, as well as sphingomyelin, mostly in soleus and in red, but not white section of gastrocnemius. Concomitantly, the activity of serine palmitoyltransferase and acid/neutral ceramidase was increased in more oxidative muscles. In conclusion, hyperthyroidism induced fiber specific changes in the content of sphingolipids that were relatively more related to de novo synthesis of ceramide rather than to its generation via hydrolysis of sphingomyelin.     

Influence of Variety,Moisture Content,Kernel Size and Applied Current Frequency on the Electric Properties of Wheat Grain

The work aimed at determination of electric properties of wheat grain in dependence on its variety, moisture, geometrical features of kernels and applied current frequency. Wheat grain of 4 Polish winter varieties: Korweta, Juma, Mikon and Kobra from harvest 2001 were used as the material for study. Grain was sized into 3 fractions: (1) > 2,8mm, (2) 2,5–2,8mm, and (3) 2,2–2,5mm. Basic geometrical features were determined for not sorted grain (control sample) and its three fractions by the use of digital image analysis. Electric properties of grain (at 11% and 15% moisture content) have been performed with the Hewlett Packard 4263B meter. Measurements of impedance, resistance, admittance, conductance, as well as equivalent parallel capacitance and equivalent series capacitance were made. Obtained results were subjected to statistical analysis with the use of Statistica? programme. Changes in electric properties of grain significantly depended on all of studied factors. Most of all significant correlations appeared between geometrical features and studied electric properties of grain of 15% moisture. Statistical analysis of the results proved significant linear correlations between electric properties of kernels and their length, perimeter and circularity coefficient R_C2 at higher measurement frequencies.     

Aflatoxins in nuts assayed by immunological methods

 Different kinds of raw and processed nuts available in the local retail market were investigated for aflatoxin content. Total aflatoxins and aflatoxin B₁ content were determined by immunoaffinity chromatography with fluorescence detection after reaction with bromine solution and by immunoenzymatic test kits. Of 29 investigated samples, 38% were contaminated. The total aflatoxin content in contaminated samples was between 1.20 μg/kg for peanuts and 5.50 μg/kg for walnuts. The concentration of aflatoxin B₁ found in contaminated samples was between 0.35 μg/kg for cashew nuts and 4.04 μg/kg for walnuts. The mean recovery of total aflatoxins was 95% for the Ridascreen test and 92% for immunoaffinity chromatography with fluorescence detection. For aflatoxin B₁ the mean recovery was 84%. Received: 4 March 1999 / Revised version: 17 May 1999     

Numerical and experimental investigation of free vibration of multilayer delaminated composite beams and plates

The use of vibration-monitoring techniques as non-destructive methods for detection of delaminations in layered composite beam and plate structures is a current field of interest for many researchers. However, an extensive search of published literature shows that information on numerical and especially experimental investigations into the dynamic behaviour of delaminated layered composite beams and plates is limited. For this reason the present authors have developed theoretical models and carried out an extensive experimental investigation to establish changes in the first three bending natural frequencies due to delaminations. The subsequent results of these numerical calculations are consistent with the results of the corresponding experimental investigations. As the result of this work models of a finite delaminated beam element and delaminated plate element have been developed. The method of modelling delaminations presented in this work enables its easy modification according to specific cases of damage (i.e. multiple delaminations). Received 12 December 99     

Hopping conductivity of metal-dielectric nanocomposites produced by means of magnetron sputtering with the application of oxygen and argon ions

Testing of electrical properties of nanocomposites (Co_0,45Fe_0,45Zr_0,1)_x + (Al₂O₃)_1+x within the concentration range of 0.30 < x < 0.65, produced by means of magnetron sputtering of a target composed of stripes of metallic alloy and dielectric, has been carried out. It has been found that the studied materials contain metallic nanoparticles of a diameter ranging from 6 to 10 nm. Alternating current conduction at x < 0.50 is realized by hopping mechanism while at x > 0.50 metallic conductivity is observed.The obtained results have been analyzed using a model of hopping conductivity in the egime developed earlier. This analysis allowed to extract dependences of activation energy ΔE_τ and times τ in a hopping regime after isochronous (15 min) thermal annealings within the range from 293 K to 673 K.     

Computational Pipeline for Reference-Free Comparative Analysis of RNA 3D Structures Applied to SARS-CoV-2 UTR Models

RNA is a unique biomolecule that is involved in a variety of fundamental biological functions, all of which depend solely on its structure and dynamics. Since the experimental determination of crystal RNA structures is laborious, computational 3D structure prediction methods are experiencing an ongoing and thriving development. Such methods can lead to many models; thus, it is necessary to build comparisons and extract common structural motifs for further medical or biological studies. Here, we introduce a computational pipeline dedicated to reference-free high-throughput comparative analysis of 3D RNA structures. We show its application in the RNA-Puzzles challenge, in which five participating groups attempted to predict the three-dimensional structures of 5′- and 3′-untranslated regions (UTRs) of the SARS-CoV-2 genome. We report the results of this puzzle and discuss the structural motifs obtained from the analysis. All simulated models and tools incorporated into the pipeline are open to scientific and academic use.