Creative measurement in view of the scope of metrology

The conception of creative measurements, i.e. measurements when the model of the object is not totally available, is presented. They are compared with routine measurements. The examples of creative measurements of odour and hand are described. The attempted motive of the thesis about metrological sense of modelling and necessity of expansion of the metrology scope is undertaken.     

Anisotropy of the electrical properties of flat textiles

Flat textiles exhibiting good electric conduction are materials that find presently increasingly broad application. Electroconductive textiles belong to the group of bodies whose properties usually show flat and normal anisotropy. The paper sets out a new method for the assessment of the flat anisotropy of properties of electroconductive textile samples in multi-directions lying in the sample plane. A new textile anisotropy index is also proposed, which constitutes a criterion enabling electroconductive textiles to be classified to either the isotropic or the anisotropic product group. An electroconductive textile property anisotropy function is introduced, which is the dependence of the resistance on the sample testing direction. The resistance of the sample was determined based on a four-electrode method. The analysis of the anisotropy of electroconductive properties of selected textile samples was also made.     

Experimental investigation of the fatigue strength of plain concrete under high compressive loading

Fatigue tests are conducted on plain concrete cylinders subjected to axial cyclic compression. The upper level of the cyclic stress ranges between 60% and 90% of the static compressive strength. A method based on volume strain measurements is used to predict the individual static strength of each tested sample. The results of fatigue tests are presented in a load versus cycles to failure diagram. The recorded values of the longitudinal strains are, plotted in terms of number of cycles. The test figures are discussed assuming that the failure is a result of both time and cycle dependent damage. For loading levels ranging up to 80% of the static strength, the number of cycles to failure shows hardly any variation with the effects of time. Above this level, the fatigue strength proves to be more sensitive to time dependent effects, as the level of loading increases.     

Crystallographic order in multi-walled carbon nanotubes synthesized in the presence of nitrogen

Multi-walled carbon nanotubes were synthesized by chemical vapor deposition from pure toluene and toluene/diazine mixtures using ferrocene as a catalyst precursor at 760 degrees C. As recently announced, characterization of the resulting nanotube films showed that, unlike pure carbon nanotubes, those grown in the presence of nitrogen have an extremely high degree of internal order, both in terms of the uniform chirality in the nanotube walls and of the crystallographic register between them. Here, the structure, defects, and morphology of the nanotubes were analyzed in depth using advanced electron microscopy techniques, and compared with existing models and observations. Nitrogen, which seems to be responsible for the dramatic structural order, was found to segregate preferentially within the core of the nanotubes.     

Nanoparticles for convective heat transfer enhancement: heat transfer coefficient and the effects of particle size and zeta potential

This work presents a study of using the Wilson Plot method to determine the convective heat transfer coefficient (CHTC) of the following nanoparticles in water as the base fluid: SiO₂, TiO₂, and Al₂O₃. The experiments were carried out in a double layer concentric glass tube in which the hot fluid and nanofluids exchange heat in a counter current fashion without direct contact. Attention was also given to the volumetric concentration, flow rate, and the size of nanoparticles to investigate their effects on CHTC. From the experiments, it was found that by adding nanoparticles, the CHTC of water can generally be enhanced and a 45% increase has been achieved with a 0.5?vol% concentration of Al₂O₃ nanoparticles at an intermediate Reynolds number around 4100. Moreover, simply reducing nanoparticle size and increasing the nanofluid flow rate do not necessarily lead to the CHTC enhancement, rather, they have adverse effects. It is concluded that the enhancement depends on the stability of the dispersed nanoparticles that can be characterized by their overall mean size and zeta potential as useful measures.     

Interactions between Lupinus angustifolius seeds lipoxygenase and native phenolic compounds in the model system

The aim of this study was to investigate the activity of lipoxygenase extracted from Lupinus angustifolius seeds and its interactions with native lupin polyphenols. The examinated enzyme is active at pH 7.5 causing peroxidation of linoleic acid. The main hydroperoxide produced in the presence of investigated lupin lipoxygenase was 13-hydroperoxy-octadecadienoic acid (13-HPODE t-t). In the presence of the phenolic compounds extracted from L. angustifolius seeds, the changes of lipoxygenase activity were observed. A distinct antioxidant effect of lupin polyphenols observed at their low concentration (0.58???g/ml) was almost completely overcome at higher concentration of phenolic compounds (2.91???g/ml). It comes probably from oxidation of polyphenols in the presence of lupin lipoxygenase. In this mechanism, polyphenol radical formation is possible. The formed radicals decrease the antioxidant efficiency of the phenolic compounds. Eventual phenoxyl radical-mediated peroxidation may be inhibited by the presence of antioxidants able to regenerate flavonoids.