An Insight into the Stages of Ion Leakage during Red Blood Cell Storage

Packed red blood cells (pRBCs), the most commonly transfused blood product, are exposed to environmental disruptions during storage in blood banks. In this study, temporal sequence of changes in the ion exchange in pRBCs was analyzed. Standard techniques commonly used in electrolyte measurements were implemented. The relationship between ion exchange and red blood cells (RBCs) morphology was assessed with use of atomic force microscopy with reference to morphological parameters. Variations observed in the Na⁺, K⁺, Cl⁻, H⁺, HCO₃⁻, and lactate ions concentration show a complete picture of singly-charged ion changes in pRBCs during storage. Correlation between the rate of ion changes and blood group type, regarding the limitations of our research, suggested, that group 0 is the most sensitive to the time-dependent ionic changes. Additionally, the impact of irreversible changes in ion exchange on the RBCs membrane was observed in nanoscale. Results demonstrate that the level of ion leakage that leads to destructive alterations in biochemical and morphological properties of pRBCs depend on the storage timepoint.     

Biomedical aspects of ion bombardment of polyethylene

Press-moulded ultra-high molecular weight polyethylene (UHMWPE) samples were subjected to ion bombardment and effects of the modification studied. Helium, nitrogen, argon and silver ions of energy 65–150 keV and fluences in the range of 1 × 10¹⁴ to 3 × 10¹⁶/cm² were applied. The consequences of the modification were studied with FT-IR, Raman and AFM techniques, contact angle measurements, bacteriostaticity and thrombogeneity tests. Surface layer oxidation, graphitization and changes to the surface geometry lead to increase of the surface energy. Modified surface exhibits bacteriostatic properties particularly for higher ion fluences. Aggregation of blood platelets on polymer surface subjected to ion bombardment is limited.     

Tamoxifen metabolite isomer separation and quantification by liquid chromatography-tandem mass spectrometry

Tamoxifen (Tam), the antiestrogen used to treat estrogen receptor-positive breast cancer is a pro-drug that is converted to its major active metabolites, endoxifen and 4-hydroxy-tamoxifen (4-OH-Tam) by various biotransformation enzymes of which cytochrome P450-2D6 (CYP2D6) is key. The usual Tam dose is 20 mg daily; however, the plasma active metabolite concentrations vary due to common genetic variants encoding the biotransformation enzymes and environmental factors (e.g., concomitant drugs) that inhibit these enzymes. Effective treatment depends on adequate Tam conversion to its active isomers. To monitor metabolite plasma levels, a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to separate and quantitate Tam, N-desmethyl-tamoxifen (ND-Tam), and tamoxifen-N-oxide (Tam-N-oxide), and the E, Z, and Z' isomers of endoxifen and 4-OH-Tam. Known standards were used to identify each metabolite/isomer. Quantitation of these metabolites in plasma was linear from 0.6 to 2000 nM. Intra- and inter-assay reproducibilities were 0.2-8.4% and 0.6-6.3%, respectively. Accuracy determined by spike experiments with known standards was 86-103%. Endoxifen, 4-OH-Tam, and their isomers were stable in fresh frozen plasma for ≥6 months. This method provides the first sensitive, specific, accurate, and reproducible quantitation of Tam and its metabolite isomers for monitoring Tam-treated breast cancer patients.     

Waste incineration with production of clean and reliable energy

Discussion about utilization of waste for energy production (waste-to-energy, WTE) has moved on to next development phase. Waste fired power plants are discussed and investigated. These facilities focus on electricity production whereas heat supply is diminished and operations are not limited by insufficient heat demand. Present results of simulation prove that increase of net electrical efficiency above 20% for units processing 100 kt/year (the most common ones) is problematic and tightly bound with increased investments. Very low useful heat production in Rankine-cycle based cogeneration system with standard steam parameters leads to ineffective utilization of energy. This is documented in this article with the help of newly developed methodology based on primary energy savings evaluation. This approach is confronted with common method for energy recovery efficiency evaluation required by EU legislation (Energy Efficiency—R1 Criteria). New term highly-efficient WTE is proposed and condition under which is the incinerator classified as highly efficient are specified and analyzed. Once sole electricity production is compelled by limited local heat demand, application of non-conventional arrangements is highly beneficial to secure effective energy utilization. In the paper a system where municipal solid waste incinerator is integrated with combined gas–steam cycle is evaluated in the same manner.     

The mechanisms of wear in burs with diamond grits

The aim of the study was to observe changes in dental burs with diamond grits after cutting and elucidate the nature of bur wear.     

Grain growth in ultrafine grained aluminium processed by hydrostatic extrusion

Ultrafine grained materials can be produced by a number of techniques among which one can distinguish hydrostatic extrusion. In aluminium, this method can be used to obtain a structure with the grain size of 300 nm and high fraction of HAGBs (more than 70%). During annealing this structure undergoes significant changes which were evaluated quantitatively. Annealing for 1 h at temperatures up to 200 °C results in normal grain growth whereas at higher temperatures or for longer annealing times a transition from normal to abnormal growth is observed. The activation energy for low temperature regime is 43 kJ/mol whereas for high temperature annealing—128 kJ/mol. The former corresponds to grain boundary diffusion whereas the latter is close to activation energy of self diffusion in aluminium. The change in activation energy well corresponds to the transition in grain growth mechanism from normal to abnormal.     

Structural changes of carotenoid astaxanthin in a single algal cell monitored in situ by Raman spectroscopy

The changes of structure of astaxanthin (AXT), a superpotent antioxidant, upon thermal stress were investigated in unicellular microalgae Haematococcus pluvialis by measuring Raman spectra in situ and analyzing obtained results with DFT calculations. Although no visual changes are observed in the Haematococcus cells upon heating, discernible changes in Raman spectra occur from -100 °C systematically up to 150 °C. The exponential increase of the Raman shift of the ν C═C band at ca. 1520 cm(-1) along with the change of the intensity ratio of bands at 1190 and 1160 cm(-1) is observed, that correlates with the changes predicted by calculations for astaxanthin conformers ordered by decreasing energy. It is assumed that AXT molecules, initially in the form of H-aggregates with the trans conformations of the end-rings, interconvert toward more stable gauche forms upon thermal stress of the algae. The applied approach enables one to follow structural changes of the carotenoid upon temperature stress both in a single algal cell and in a multicellular sample in situ. Obtained information might be of use to improve the industrial process of extraction of AXT in its most bioavailable form.     

Dielectric properties of chiral honeycombs – Modelling and experiment

Electromagnetic properties of mechanically chiral honeycomb structures are investigated. In extension to previous works on the subject, rigorous analysis is performed above the quasi-static frequency range. Theoretical considerations and full wave 3D electromagnetic simulations are conducted to prove that, for the honeycombs of interest, higher order harmonics due to structure periodicity are attenuated away from the panel surface at frequencies up to several GHz, which covers a number of popular ISM bands. As a consequence, only individual plane TEM waves are observable at practical locations of transmitters and receivers away from the panel. Under the same conditions, it is demonstrated that the structural chirality does not translate into chiral electromagnetic behaviour. In other words, orthogonal modes of the honeycomb scenarios are linearly polarised, and transformation of the electromagnetic energy into heat occurs purely as a result of classical conductivity or loss tangent, which are low for the low-density panels made of low-loss dielectric cores. This indicates that EMC or shielding characteristics can only be designed either by utilizing the phenomenon of wave reflections, or by equipping the panels with additional foils on surfaces or absorbing foams in air volumes. While precise measurements of final-sized honeycomb panels remain as a challenging task for further work, preliminary experiments have been performed showing good agreement with theoretical and computed predictions.     

Influence of current transformer saturation on line current differential protection algorithms

The performance of line current differential protection algorithms during current transformer (CT) saturation is analysed. The study covers popularly used algorithms and presents their degree of immunity to CT saturation. The degree of error in phasor measurement due to CT saturation is estimated through simulation studies and this information is used to decide the CT dimensioning for the relay     

Metaheuristic approaches for the two-machine flow-shop problem with weighted late work criterion and common due date

In this paper, metaheuristic approaches for the two-machine flow-shop problem with a common due date and the weighted late work performance measure (F2|_dj=d|_Yw)$(F2|d_j=d|Y_w)$ are presented. The late work criterion estimates the quality of a solution with regard to the duration of the late parts of jobs, not taking into account the quantity of the delay for the fully late activities. Since the problem mentioned is known to be NP-hard, three trajectory methods, namely simulated annealing, tabu search and variable neighborhood search are proposed based on the special features of the case under consideration. Then, the results of computational experiments are reported, in which the metaheuristics were compared one to each other, as well to an exact approach and a list scheduling algorithm.