Reliability of force–time curve characteristics during maximal isometric leg press in differently trained high-level athletes

The aim of this research was to establish the metrologic values of the isometric force–time characteristics of leg extensors in differently trained, healthy male athletes and non-athletes. 99 subjects performed a standardized “isometric leg press” test. Even though the results showed a high statistical significance in terms of representativeness, generalizability and reliability for all contractile characteristics of observed measured variables, different methodological approaches were required in order to obtain the most valid results for differently trained and untrained subjects. Based on the results obtained, and from the aspect of the methodology of testing different isometric force characteristics, it was possible to conclude that the standardization of the isometric leg press requires two trials in football, where the most reliable data was from the first trial (the communality rates (H²) from 0.866 to 0.969). Water polo and basketball require three trials. The most reliable data was from the third and second trial in water polo (H² from 0.909 to 0.986). In basketball the most reliable data was from the second trial (H² from 0.824 to 0.987). The untrained healthy adult population requires four trials, and the most reliable data was from the third trial (H² from 0.961 to 0.995).     

Effects of access phases lengths on performance of IEEE 802.15.6 CSMA/CA

In this paper, we study interplay of prioritizing mechanisms in recently released IEEE 802.15.6 standard for Wireless Body Area Networks (WBANs). Among eight User Priorities (UPs) we study the impact of access phases lengths and CSMA/CA mechanism on the network performance. We consider a star-topology single-hop WBAN in which the hub operates in beacon mode with superframe boundaries. Our study is conducted in saturation regime and an error prone channel in order to indicate performance bounds for all UPs. We have developed an analytical model for the CSMA/CA-based Medium Access Control (MAC) layer of IEEE 802.15.6 which includes Markov chain and probabilistic models for all UPs. In order to validate the analytical model we have developed a simulation model in OPNET. We investigate the effectiveness of deploying exclusive access phases and second random access phase on the network performance. We also examine the medium utilization and normalized throughputs of all UPs. Obtained performance bounds indicate potential tradeoff between the prioritizing parameters which affect the saturation throughputs.     

Potential development of bioethanol production in Vojvodina

The Autonomous Province of Vojvodina is an Autonomous Province in Serbia, containing about 27% of its total population according to the 2002 Census. Contribution of renewable energy sources in total energy consumption of Vojvodina contemporary amounts to less than 1%, apropos 280 GWh/year. By combining of methods of introduction of new and renewable sources, systematic application of methods for increasing of energetic efficacy, as well as of introduction of the new technologies, percentage of contribution of the non-conventional energy sources in Vojvodina could be increased to as much as 20%. This paper presents the potential of development of bioethanol production in Vojvodina. Production of bioethanol on small farms can be successfully applied for processing of only 30 kg of corn per day, with obtaining of crude ethanol in the so-called “brandy ladle” and use of lygnocellulosic agricultural wastes as an energy source. In a case of construction of a larger number of such plants, the only possible solution is seen in the principle of construction of the so-called “satellite plants”, which will on small farm produce crude ethanol, with obtaining and consumption of stillage for animal feeding, and consumption of agricultural wastes as energetic fuels. If stillage is to be used as feed in wet feeding, it is estimated that, because of restrictions established by the magnitude of animal farm, the upper limit of capacity of such enterprises that process is at some 10–15 tons of corn per day, and production of 3000–3500 hL of absolute ethanol per day. In such a case, for animal feeding necessary is to have herd with 1300–1700 of milking cows or 5000–25,000 heads of sheep and/or pigs. Technological model of separate grain processing ad bioethanol production from dextrose hydrolysates of starch is interesting for countries possessing plants for bioethanol production from molasses and plants for cereals processing into starch and dextrose hydrolysates of starch.     

Spillover of primary oxides as a dynamic catalytic effect of interactive hypo-d-oxide supports

The aim of the present paper is to introduce electron conductive and d-d-interactive individual and composite hypo-d-oxides of increased altervalent capacity, or their suboxides (Magneli phases), as catalytic supports and therefrom provide: (i) the Strong Metal-Supports Interaction (SMSI) effect and (ii) dynamic spillover interactive transfer of primary oxides (M-OH) for further electrode reactions and thereby advance the overall electrocatalytic activity. Since hypo-d-oxides feature the exchange membrane properties, the higher the altervalent capacity, the higher the spillover effect. This is the reason why anatase titania has now been doped with a certain amount of colloidal tungstenia (WO₃) ingredient, and the latter individually employed as the interactive catalyst support. Potentiodynamic experiments have shown that the reversible peak of the primary oxide growth on Pt, Ru and Au supported upon hypo-d-oxides and suboxides becomes distinctly increased in the charge capacity and shifted to remarkably more negative potential values, so that it starts even within the range of H-adatoms desorption, while its reduction extends until and merge with the UPD of hydrogen atoms. With wet tungstenia-doped titania-supported Pt catalyst in membrane cells, these peaks dramatically increase in their charge capacity and reversibly become shrunk with decreased moisture content in the feeding inert gas mixture, and vice versa. Such distinct potentiodynamic scans in conjunction with some broadened complementary kinetic electrocatalytic improvements, rising from the same hypo-d-oxide and/or suboxide interactive support effects, have been proved to be the best and comparable experimental evidence for the spillover effect of primary oxides.     

Surface modification of macroporous glycidyl methacrylate based copolymers for selective sorption of heavy metals

Two samples of macroporous poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate), poly(GMA-co-EGDMA), were synthesized by suspension copolymerization and modified with amines. Initial poly(GMA-co-EGDMA), and the samples modified with ethylene diamine [poly(GMA-co-EGDMA)-en], diethylene triamine [poly(GMA-co-EGDMA)-deta] and triethylene tetramine [poly(GMA-co-EGDMA)-teta], were characterized by mercury porosimetry, FTIR spectroscopy and elemental analysis. The most pronounced increase of specific surface area (75%) was observed for poly(GMA-co-EGDMA)-teta sample with smaller particles (D < 150 μm). The Cu(II) sorption was rapid, depending on porosity of amino-functionalized samples and ligand type. For poly(GMA-co-EGDMA)-deta and poly(GMA-co-EGDMA)-teta sorption half time required to reach 50% of total sorption capacity, t _1/2, were around 3 min. Sorption capacities for Cu(II), Co(II), Cd(II) and Ni(II) as well as for Cr(VI), Co(II), Cd(II) and Ni(II) ions were determined under competitive conditions as a function of pH, ligand type and porosity at room temperature. The results indicate selectivity of poly(GMA-co-EGDMA)-deta for Cu(II) over Cd(II) of 3:1 and for Cu(II) over Ni(II) and Co(II) of 6:1. The decrease in particle size of poly(GMA-co-EGDMA)-teta caused the increase of sorption capacities for all metal ions. At pH 1.8 the selectivity of poly(GMA-co-EGDMA)-teta with smaller particles for Cr(VI) over Ni(II), Co(II) and Cd(II) ions was 8.5:1.     

Perspectives of sustainable development in countries of Southeastern Europe

Countries of SE Europe are at very beginning of planning of their development in accordance with theoretical concept of sustainable development. Sustainable development is defined as the basic imperative and the only model of development in a longer period of time. The basic indicators of sustainable development represent a very useful and quality way for measuring and monitoring the state of sustainable development, as in every country individually so as in the regions and globally as a whole. Values of the indicators of all four subsystems in observed countries are within expectation. Also the current level of development of every country separately is taken into account and in accordance to that it is defined the current position of any country in respect to its international requests. The special value is given by the comparison of obtained results of the state in the developed EU countries, according to which there is an impression of equal degree of sustainable development in France and Germany, whereas the data regarding the state of sustainable development in Greece and at Slovenia has been improved between two analysis. Taking into account the results of the previous and current research there is a clear need for regular observation of the state of every indicator individually but also the need to observe the relationship among them as a whole. The special attention needs to be given to the intensive monitoring of indicators of economic and ecological subsystem. The research showed, among other things, to the fragile relationship of values of indicators of economic and ecological subsystem, by which any change in values of one indicator consequently leads to the changes in the final result. Both conducted researches point to the fact that the value of the mentioned indicators changes at the fastest pace.     

Effect of thermal oxidative ageing on the morphology of natural rubber networks as viewed by ESR

The change of network morphology of unfilled sulfur crosslinked natural rubber exposed to thermal oxidative ageing has been studied. Three model networks with different sulfur contents (efficient network, semi‐efficient and conventional vulcanizate) have been analysed by applying spin probe ESR, equilibrium swelling measurements and mechanical measurements. By combining the density distribution deduced from the complex ESR spectra and the equilibrium swelling density, it is shown that the major network changes occur in the networks with predominantly polysulfidic bonds (conventional network) after 96 h of ageing at 373 K. The effect of ageing on the network with predominantly monosulfidic bonds is much less pronounced. Both effects (main chain scission and additional local crosslinking) have been analysed in the course of prolonged ageing up to 240 h. A correlation between network structure and its mechanical performance is established. © 2000 Society of Chemical Industry     

Molecular identification and population dynamic of Anisakis pegreffii (Nematoda: Anisakidae Dujardin, 1845) isolated from the European anchovy (Engraulis encrasicolus L.) in the Adriatic Sea

Anchovy Engraulis encrasicolus (L.) is a coastal pelagic and euryhaline species that represents the only European species of the family Engraulidae, with a widespread distribution. In Croatia, it is marketed fresh, frozen, salted or marinated and mainly exported to Italy and Spain, however Anisakis sp. larval infection is frequently the reason for border rejection. Since it is known that the prevalence and intensity of Anisakis infection varies with fish species, fishing area and season, the aim of our study was to identify Anisakis sp. parasitizing European anchovy and infer its population dynamic through a 2.5-year period. Larvae were found coiled and encysted on the external wall of intestine (94%) and reproductive organs (6%), rarely in fillets. Prevalence was 76.1% (95% confidence limits 74.51-77.56%), mean abundance 6.59 (bootstrap 95% confidence limits 5.81-7.26) and mean intensity 8.67 (bootstrap 95% confidence limits 7.82-9.35). The partial CO2 mitochondrial DNA sequence of the isolated anisakids confirmed clustering of the anchovy parasite within A. pegreffii sister group. Parasite population structure showed plasticity inferred by fishing ground, sampling year and fish gender and size. Compared to anisakid prevalence/abundance in other fish, the European anchovy in the Adriatic Sea represents a moderately high-infected paratenic host, although in the Mediterranean and Atlantic waters, anchovies have shown strikingly lesser values of prevalence. Since this host represents one of the most attractive Mediterranean fisheries products traditionally consumed without thermal preparation that in any case would not disrupt larval antigenicity and prevent human allergies, and given the high prevalence of the anisakid within the host, it is necessary to include anchovy into more firm risk assessment frames in order to develop measures that will support the safe alimentary production and consumption of seafood.     

Covalent Functionalization of Multi‐walled Carbon Nanotubes with a Gadolinium Chelate for Efficient T1‐Weighted Magnetic Resonance Imaging

Given the promise of carbon nanotubes (CNTs) for photothermal therapy, drug delivery, tissue engineering, and gene therapy, there is a need for non‐invasive imaging methods to monitor CNT distribution and fate in the body. In this study, non‐ionizing whole‐body high field magnetic resonance imaging (MRI) is used to follow the distribution of water‐dispersible non‐toxic functionalized CNTs administrated intravenously to mice. Oxidized CNTs are endowed with positive MRI contrast properties by covalent functionalization with the chelating ligand diethylenetriaminepentaacetic dianhydride (DTPA), followed by chelation to Gd³⁺. The structural and magnetic properties, MR relaxivities, cellular uptake, and application for MRI cell imaging of Gd‐CNTs in comparison to the precursor oxidized CNTs are evaluated. Despite the intrinsic T₂ contrast of oxidized CNTs internalized in macrophages, the anchoring of paramagnetic gadolinium onto the nanotube sidewall allows efficient T₁ contrast and MR signal enhancement, which is preserved after CNT internalization by cells. Hence, due to their high dispersibility, Gd‐CNTs have the potential to produce positive contrast in vivo following injection into the bloodstream. The uptake of Gd‐CNTs in the liver and spleen is assessed using MRI, while rapid renal clearance of extracellular Gd‐CNTs is observed, confirming the evidences of other studies using different imaging modalities.     

Assessment of the load-bearing capacity of a primary pipeline

High-alloyed Cr-Ni-based two-phase stainless steel (SS) cast alloys are commonly used in nuclear power plants. The mechanical equipment in these facilities can contribute to a reduction in its resistance to stable crack growth as a result of extended operating times and high temperatures. The toughness of these materials strongly depends on their delta (δ) ferrite content, which spinodally decomposes into two phases with different ratios of Cr and Ni at a relatively low (slightly above 300 °C) temperature. This temperature is similar to the operating temperature of the vital parts, for example, the coolant system. The formation of two phases with the same crystal structure but different lattice parameters causes internal elastic stresses that result in a hardness increase and an impact-toughness decrease. The result is an increased risk of crack formation in the stress-concentration zones such as the critical regions of different welded joints (e.g. “L, T, K and X” shapes). The values of the critical stress intensity factor change according to its position along the crack contour. Therefore, the aim of our study was to assess the influence of the materials’ changes on the crack extension and the decrease of the primary pipeline’s bearing capacity by taking account of the increased temperature and time of operation for the given loading conditions. The SINTAP (European Structural Integrity Assessment Procedure) was used for this assessment.