Selected Mediators of Inflammation in Patients with Acute Ischemic Stroke

During a stroke, a series of biochemical and metabolic changes occur which eventually lead to the death of cells by necrosis or apoptosis. This is a multi-stage process involving oxidative stress and an inflammatory response from the first signs of occlusion of a blood vessel until the late stages of regeneration and healing of ischemic tissues. The purpose of the research was to assess the concentration of pro-inflammatory cytokines IL-6 and TNF-α in the blood serum of patients with ischemic stroke (AIS) and to investigate their role as new markers in predicting functional prognosis after thrombolytic therapy. The researches have shown that the concentrations of the measured biomarkers were higher compared to the control group. Serum levels of IL-6 and THF-α before the initiation of intravenous thrombolysis were lower in the subgroup of patients with a favourable functional result (mRS: 0–2 pts) compared to the group of patients with an unfavourable functional result (mRS: 3–6 pts). A positive correlation was found between the concentration of IL-6 and TNF-α in patients with AIS during <4.5 h and on one day after the onset of stroke, which means that the concentration of IL-6 increases with the increase in TNF-α concentration. It has also been shown that higher levels of IL-6 in the acute phase of stroke and on the first and seventh days, and TNF-α during onset, were associated with poorer early and late prognosis in patients treated with intravenous thrombolysis. A relationship was found between the level of IL-6 and TNF-α in the subacute AIS and the severity of the neurological deficit. It has been shown that the investigated biomarkers may be a prognostic factor in the treatment of thrombolytic AIS.     

Quenching of Protein Fluorescence by Fullerenol C60(OH)36 Nanoparticles

The effect of the interaction between fullerenol C₆₀(OH)₃₆ (FUL) and alcohol dehydrogenase (ADH) from Saccharomyces cerevisiae and human serum albumin (HSA) was studied by absorption spectroscopy, fluorescence spectroscopy, and time-resolved fluorescence spectroscopy. As shown in the study, the fluorescence intensities of ADH and HSA at excitation wavelengths λ_ex = 280 nm (Trp, Tyr) and λ_ex = 295 nm (Trp) are decreased with the increase in the FUL concentration. The results of time-resolved measurements indicate that both quenching mechanisms, dynamic and static, are present. The binding constant K_b and the number of binding sites were obtained for HSA and ADH. Thus, the results indicated the formation of FUL complexes and proteins. However, the binding of FUL to HSA is much stronger than that of ADH. The transfer of energy from the protein to FUL was also proved.     

Comparative tests of plasma-surfaced nickel layers with chromium and titanium carbides

This article presents the results of structural tests of composite coatings on a NiSi₂B alloy matrix containing carbides of Ti and Cr, which have been plasma surfaced from a powder mixture onto a low-alloyed steel substrate. The content and distribution of the strengthening phase in the matrix have been determined. It has been shown that the different nature of the interaction between Ti and Cr carbides and the liquid Ni alloy significantly affects the formation of composite surfacing layers as well as the distribution and content of strengthening phase particles in the matrix.     

Quenched steel welding

The aim of this research was to develop a process for welding BORON 27 type quenched steel, manufactured in Finland. The composition of a shielding gas mixture was selected by means of trials: 90% Ar, 5% CO₂, and 5% O₂. Joints were reproduced by this method, i.e. welded, quenched joints as well as unquenched welded joints, and were tested for quality. Tests included X-ray radiography, macroscopic testing, hardness tests, and tearing and bending resistance tests. The results of these tests were presented in the article.     

A kinetic-empirical model for particle size distribution evolution during pulverised fuel combustion

Particle size is an essential parameter in pulverised fuel (PF) combustion as many of the problems or further areas of development in these systems are strongly influenced by the fuel and ash size distribution. This is particularly true for dynamic processes like pollutant formation, corrosion, erosion, slagging and fouling and the related decrease of the combustion and boiler efficiency. The evolution of particle size distribution (PSD) is a complex interaction of various competing chemical and physical transformations. Char oxidation, devolatilization and fragmentation, etc. represent first line physical and chemical transformations which can amend the particle size in the radiation zone. The evolution of the PSD represents the convolution of all of these physical and chemical transformations, operating over the entire size distribution. As a consequence, it is difficult to extract the relative importance of all competing size altering processes from the experiments. Various models such as break-up, thermal stress, shrinking core, percolation and particle-population model have been developed by incorporating numerous ash transformation mechanisms to predict the particle size evolution during the pulverised fuel combustion. The present work describes an adaptation of the numerical kinetic-based particle-population balance for predicting particle size evolution during PF combustion developed by Dunn-Rankin and Mitchell. The model is further simplified analytically and validated against experimental results. Several empirical parameters derived from the experiments are incorporated into the model. The resulting simplified PSD evolution model shows good agreement with literature and experimental results, with maximum 10% absolute standard deviation.     

The influence of oxygen ambient annealing conditions on the quality of Al/SiO2/n-type 4H-SiC MOS structure

The effect of reoxidation process in O₂ on the electrical properties of metal-oxide-semiconductor (MOS) capacitors fabricated on n-type 4H-SiC (0 0 0 1) is investigated. All samples were oxidized in wet oxygen at temperature of 1175 °C. Reoxidation process was carried out on four of the five samples. Samples were annealed at temperature of 700 °C and 800 °C for different process times. The reoxidation process in oxygen improves the quality of the dielectric layer and the interface of Al/SiO₂/n-type 4H-SiC MOS structure. The best quality of the SiO₂/SiC interface can be achieved for the MOS structure annealed in O₂ at higher temperature (800 °C) for longer time. However, higher and more uniformly distributed values of breakdown voltage were obtained for MOS structures reoxidized at temperature of 700 °C.     

Antioxidants in thermally treated buckwheat groats

The seeds of buckwheat (Fagopyrum esculentum Moench L.) were dehulled and then, following milling, extruded on a counter rotating, twin-screw extruder with the different barrel temperature profiles: 120, 160, and 200 degrees C. After extrusion cooking process, the following compounds were analyzed: free and conjugated phenolic acids, total polyphenols (TPC), tocopherols (T) and tocotrienols (T3), inositol phosphates (IP), reduced glutathione (GSH), and melatonin (MLT). The antioxidant capacity and superoxide dismutase-like activity (SOD-like activity) were determined in the groats and extrudates. Extrusion caused a significant decrease in all the compounds tested, except for phenolic acids. The content of IP decreased by 13%, that of GSH by 42%, and that of T + T3 by 62%. A three-fold lower level of MLT and TPC was noted whereas the SOD-like activity disappeared when compared to the nonextruded material. A two-fold higher content of phenolic acids (free and released from ester bonds) was observed. In spite of the clear decrease in the investigated antioxidants, the extruded dehulled buckwheat seeds contained still significant content of bioactive compounds, which resulted in as little as an average 10% decrease of the antioxidant capacity.     

Experimental determination of intrinsic permeability of limestone and concrete: Comparison between in situ and laboratory results

The study is concerned with development of the method of in situ measurement of air permeability of porous media. The method applied consists of creating a vacuum in a drilled hole and then studying the increase in pressure over time. The dimensions of the hole are small enough to consider the test as being nondestructive. The paper is composed of three parts. The first one develops the theoretical background used for interpretation of experimental results. The second part describes experimental procedure and device for in situ measurements. The parametric studies of principal factors which may influence the measurements such as the sampling frequency, the observation time and the boundary conditions were performed. The last part includes a discussion of results of the measurements of air permeability performed on large blocks of limestone and concrete. These blocks simulate in situ conditions. On the other hand, from these blocks, cylindrical samples were cored and standard gas and liquid laboratory tests were carried out. The results obtained show good agreement between intrinsic permeability obtained with the in situ device and laboratory tests, confirming the usefulness of the proposed tool.