The article presents the procedure for how to establish a mathematical model of nitrogen oxides formation based on the theory of dimensional analysis. The model is based on selected physical quantities (parameters) measurable during regular operation of a heat generation plant. The objective of using dimensional analysis to describe nitrogen oxides formation is to show that between operating parameters of the combustion equipment and the NOx formation there is a significant correlation.
The obtained results, which are further described in this article, have proved this fact. The obtained formula expressing nitrogen oxides formation, based on dimensional analysis, applies universally to any boiler fuelled by coal, gas or biomass. However, it is necessary to find C, m, n constants for the formula by experiment, individually for each type of boiler and used fuel. The experiment is based on on-line measurements of selected operational parameters for a given boiler, combusting a certain type of fuel with its actual moisture content and calorific value. The methodology, described in this article, helps to find relationships between the operational parameters and the formation of NOx emissions for a particular furnace. The developed mathematical model has been validated with boilers fuelled by black coal and biomass. Both the results obtained from direct measurements of NOx in both types of boilers, and the results obtained by calculation using equation based on the dimensional analysis, are in a very good accord. When burning coal, the variation between NOx expression from the model and the on-line measurements ranges between -12.23 % and + 9.92 %, and for burning biomass between -0.54 % and 0.48 %.
The intention of the authors is to inform the professional community about the suitability of the dimensional analysis to describe any phenomena for which there is currently no exact mathematical formulation based on differential equations or empirical formulas. Many other examples of dimensional analysis applications in practice may be found in the work of Čarnogurská and Příhoda (2011).
In modern microelectronics progress has been made towards low power ultra large-scale integration (ULSI), and nano-structure devices such as single electron transistors and quantum dots. In this technology application of new materials, which includes high-κ dielectrics for the MOSFET transistors, with extraordinary purity and uniformity is required. Failure analysis and reliability investigations of such films very often requires highresolution local measurements of electrical surface parameters. This kind of experiments can be performed using conductive atomic force microscopy, which provides simultaneous measurement of surface topography and current ?owing through the investigated layer. In order to acquire reliable data, there was designed a precise measurement and control system, which included a low-noise current-to-voltage converter of picoampere resolution, a scanning stage with control electronics and a data acquisition system. In the paper we describe the architecture of the designed and applied experimental set-up. We also present results of simultaneous measurements of topography and current on gold and highly oriented pyrolytic graphite (HOPG).
In this study, the synthesis of copper-based multi-walled carbon nanotube composites is described. Over the last years, carbon nanotubes (CNTs) have been widely used in many scientific research fields and have found applications in several sectors, e.g. for water treatment. This work focuses on combining the exceptional characteristics of CNTs, such as high specific surface area and antibacterial properties, with the antimicrobial/ antivirus features of copper oxides. The influence of synthesis parameters and thermal treatment on the final product was studied. Copper leakage was evaluated at both pH 5 and pH 7, confirming the possibility of applying Cu-based MWCNT composites in water filtration systems.
This study was conducted to determine the serum and milk levels of thiobarbturic acid-reac- tive substances (TBARS), nitric oxide (NO), superoxide dismutase (SOD), glutathione peroxi- dase (GSH-Px), vitamin E and selenium, IL-4 and IL-6 in lactating dairy cows affected with bloody milk using commercially available ELISA kits. Milk and whole blood samples were collected from 60 cows affected with bloody milk and 20 apparently healthy cows for control. In the serum, levels of GSH-Px and SOD were significantly (p˂0.05) higher in healthy cows compared to cows affected with bloody milk while the levels of TBARS and NO were significantly (p˂0.05) higher in affected cows. In the milk, levels of SOD, TBARS and NO were significantly (p˂0.05) higher in affected cows. In the serum, levels of vitamin E were significantly (p˂0.05) lower in affected cows compared to healthy cows, while no significant changes were observed in the levels of this vitamin in the milk between healthy and affected cows. In the serum, levels of selenium were significantly (p˂0.05) lower in affected cows while in milk, selenium levels were significantly (p˂0.05) higher in affected cows compared to healthy ones. Levels of IL-4 were significantly (p˂0.05) lower in the serum and milk of affected cows compared to healthy cows while levels of IL-6 were significantly (p˂0.05) higher in both serum and milk of affected cows. Results of this study suggest a possible role of oxidative stress in the pathogenesis of bloody milk in dairy cows.
The paper presents the results of research on nanocomposite nickel/graphene oxide (Ni / GO) coatings produced by electrochemical reduction method on a steel substrate. Discussed is the method of manufacturing composite coatings with nickel matrix and embedded graphene oxide flakes. For comparative purposes, the studies also included a nanocrystalline Ni coating without embedded graphene oxide flakes. Graphene oxide was characterized by Raman spectroscopy, infrared spectroscopy (FTIR) and transmission (TEM) and scanning (SEM) electron microscopy. Results of studies on the structure of nickel and composite Ni/GO coatings deposited in a bath containing different amount of graphene oxide are presented. The coatings were characterized by scanning electron microscopy, light microscopy, Raman spectroscopy and X-ray diffraction. The adhesion of the prepared coatings to the substrate was examined by the scratch method. The microhardness of the coatings was measured using the Vickers method on perpendicular cross-sections to the surface. Corrosion tests of the coatings were investigated using the potentiodynamic method. The influence of graphene oxide on the structure and properties of composite coatings deposited from baths with different content of graphene oxide was determined.
In this study, to investigate effects of rhenium addition on the microstructures and mechanical properties, 15Cr-1Mo ODS ferritic steels with rhenium additions were fabricated by the mechanical alloying, hot isostatic pressing, and hot rolling processes. Unremarkable differences on grain morphologies and nano-oxide distributions were estimated in the microstructure observations. However, the ODS ferritic steels with 0.5 wt.% rhenium showed higher tensile and creep strengths at elevated temperature than that without rhenium. It was found that rhenium is very effective to improve the mechanical properties.
In order to enhance bioactive properties of titanium 99.2 used in implantology and various biomedical applications, numerous methods to form tight oxide coatings are being investigated. Some of these interesting techniques for generating TiO2 coatings include: electrochemical methods with anodizing, electric discharge treatment, plasma methods (PVD) and diffusive methods (i.e. oxidation in a fluidized bed). Each method aims to create a thin homogenous oxide coating characterized with thermal stability and repassivation ability in the presence of body fluid environment. However, new methods are still sought for increasing the biocompatibility of the substrate following a change in the intensity of depositing on the oxide coating compounds with high biocompatibility with body tissues, including hydroxyapatite, which constitutes the basis for subsequent osseointegration processes. The article presents investigation of HAp formation on titanium substrate surface after hybrid oxidation process. Hybrid surface treatments combine methods of fluidized bed atmospheric diffusive treatment FADT with the PVD surface treatment realized with different parameters (FADT – 640°C / 8h and PVD – magnetron sputtering with TiO2 target). In order to investigate the effects of hybrid oxidation and the formation of HAp molecules, SEM-EDS, SEM-EBSD, STEM-EDS, RS, nanoindentation and Kokubo bioactivity tests (c-SBF2) were carried out. The hybrid method of titanium oxidation, proposed by the Author, presents a new outlook on the modification and development of the properties of oxide coatings in the area of biomedical applications. Combining the ways of Ti Grade 2 oxidation in the hybrid method highly improves the formation of hydroxyapatite compounds and shows the potential of applying such a technique in implantology, where the intensive growth of bone tissues is crucial.
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