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Background Cytomegalovirus (CMV) seroprevalence varies between 60% in developed countries and 100% in developing countries. The aim of this study was to assess CMV seroprevalence in representative sample of children in Bosnia and Herzegovina and to identify possible factors associated with CMV. Methods Blood samples and surveys were collected from 253 children at the Department of Paediatrics and Department of Infectious diseases of University Clinical Hospital Mostar. Blood sera were tested for the presence of CMV IgG antibodies by ELISA. CMV seroprevalence was correlated with age, gender, household members, presence of pets and animals in household, attendance of day-care and summer camps and use of already used cutlery. Results Overall CMV seroprevalence among children was 56.5% (P = 0.038) and raised with age of children from 44.4% in early preschool children up to 73.9% in adolescents (P = 0.002). There was no significant difference in the CMV seroprevalence between genders (P = 0.732). Significantly higher rate of the CMV seroprevalence was observed among children having pets or domestic animals (P = 0.015), among those who attended summer sport camp or school camp (P = 0.04) and among children using of dirty cutlery and glasses (P = 0.039). Conclusions More than half of tested children were CMV seropositive with significantly higher rate in older children. Higher CMV seroprevalence was in correlations with possession of the pets or domestic animals, attendance at the summer sport camp or school camp and use of dirty cutlery and glasses.

Utilization and reuse of waste rubber tires in concrete leads to sustainable construction. There are number of studies that have been conducted on concrete with rubber as aggregate in order to maintain mechanical properties and durability of material. Contrary, only several studies have been conducted on usage of waste rubber tires as aggregate in reinforced concrete elements and systems. These review paper summaries and compare independent research works and justifies weather these aggregates are possible to utilize improved behavior of concrete elements or not. According to general conclusions on fundamental properties of rubberized elements it is evident that the waste rubber tire aggregates can be used as partial replacement of both coarse aggregates and fine aggregates. Previous research on structural elements shows that replacement of the natural aggregate with recycled tire aggregate in concrete, will produce structural elements with improved behavior: increased capacity for deformations (ductility), better dissipation of energy, and higher damping, in comparison with standard concrete made with conventional aggregates. However, the increased content of rubber in concrete also has negative effects, for example reduction of compressive and tensile as well as reduction of Young's modulus of elasticity. The results of these experimental studies are not sufficient to reach a general consensus on the application of recycled rubber in concrete and its effect on the behavior of structural elements. Inconsistency of the effects of recycled rubber in the concrete on the static and dynamic properties of reinforced-concrete structures indicate that there is uttered need for further research.

The oligo(ethylene glycol) dimethacrylate (OEGDMA), one of the most commonly utilized crosslinking monomers, was used to tailor thermoresponsive POEGDMA hydrogels by varying the monomer/solvent feed ratio (from 10 to 100 wt% of monomer). For the first time, synthesis of different POEGDMA homopolymeric networks was performed by gamma radiation, and due to the expected thermoresponsiveness their temperature-dependent properties were extensively analysed. The sol-gel study was performed as the first step after radiation-induced synthesis. The swelling properties were investigated over the wide pH (2.2–9.0) and temperature (5–80 °C) range. Characterization of structure and properties was additionally conducted by SEM, DSC, FTIR, and UV–Vis spectroscopy. The results indicated that all POEGDMA hydrogels showed a high gel content, inverse thermoresponse and volume phase transition temperature (VPTT) with no respect to initial preparation. On the other hand, by altering the monomer/solvent ratio in the prepolymerisation mixture a large diversity in the microstructure, swelling capacity and VPTT was obtained. © 2019 Elsevier Ltd This is the peer-reviewed version of the following article: Suljovrujic, Edin, Zorana Rogic Miladinovic, Maja Micic, Denis Suljovrujic, and Dejan Milicevic. "The influence of monomer/solvent feed ratio on POEGDMA thermoresponsive hydrogels: Radiation-induced synthesis, swelling properties and VPTT." Radiation Physics and Chemistry 158 (2019): 37-45. [http://dx.doi.org/10.1016/j.radphyschem.2018.12.034] Published version available at: [http://vinar.vin.bg.ac.rs/handle/123456789/8048]

The electrochemical behaviour of potential antitumor benzimidazole derivatives (benzo[b]thieno[2,3-b]pyrido[1,2-a]benzimidazoles and benzimidazo[1,2-a]quinolines) bearing one or two piperazine substituents was studied at a glassy carbon electrode (GCE) using cyclic and square-wave voltammetry in a wide range of pH values and potential scan rates. The electrochemical oxidation of the studied benzimidazoles proceeded via one or two electrode reactions assigned to the oxidation of one or two piperazine substituents, respectively. The oxidation of piperazine ring involved the transfer of two electrons and one proton in a pH-dependent, kinetically controlled electrode reaction, followed by a homogenous chemical reaction (EC mechanism). Both the reactants and the products of EC reactions were strongly adsorbed on the GCE surface. The electrochemical reduction occurred in one quasireversible, pH-dependent step, followed by a chemical transformation of the electrochemically formed product. The proposed reduction mechanism was related to the cyano moiety. The assignment of electroactive sites in molecules of interest was confirmed by theoretically calculated, using the PM6 method, differences of Net atomic charges between the cation (or anion) and neutral molecule.

Cross-border energy exchange in the electricity market environment requires high quality measurement and accounting procedure considering the fairness in technical and economic sense. In order to fulfill these requirements, the necessary step is to clarify all uncertainty contributions at the metering point and to correct the exchanged energy for corresponding systematic errors. This approach resulted by a mathematical model for energy correction. The model is briefly presented and the sensitivity analysis of the model is performed: the impact of the current, voltage and phase displacement of the measuring transformers, error of the energy meter and voltage drop in voltage measurement circuits to the corrected energy. The presented procedure shows that the voltage drop has the highest impact to the corrected energy.

This review explored areas related to the use of concrete-based and cement- based composite materials that can protect against electromagnetic radiation. Based on their potentially desirable properties related to protection against electromagnetic radiation, this paper discusses four different types of admixtures in concrete composites: fly ash, carbon nanotubes, titanium dioxide, and zinc ferrite. The analysis of electromagnetic radiation protection was studied for the frequency range of non-ionizing radiation up to 10 GHz, where wireless communication devices typically operate. This review paper also discusses the influence of these admixtures on the other properties of concrete. This paper can serve as a resource for determining the most optimal and effective methods for protecting against electromagnetic radiation using concrete composite elements.

Measurement procedures in cross-border energy exchanges usually neglect the associated measurement uncertainties, which is likely to result in financial damage to one, or both, transmission system operators. In this paper, measurement uncertainty analysis at the measurement point is extensively described and a correction procedure for its systematic contributions is presented. Aiming to develop a fair procedure for the exchanged energy distribution among transmission system operators, the concept of the virtual measuring point is introduced, taking into consideration measurement uncertainties and generated transmission losses. After performing the correction procedure, the virtual measuring point is converted into the corrected virtual measuring point, whose energy measurement is used for the final billing procedure. The presented method was tested in a practical example with data from a Croatian transmission system operator Ltd. and it was confirmed that the correction procedure can be of great interest for transmission system operators.

In continuation of our investigation of the dependence of the first electrochemical oxidation potential, Ep1, on the electronic structures of flavonoids, the potentials of nine additional flavonoids (hesperetin, daidzein, kaempferol, acacetin, naringin, neohesperidin, hesperidin, quercitrin, and gossypin) were assessed using square-wave voltammetry on a glassy-carbon electrode in aqueous buffer solutions with a pH of 3 and 7. Our standard model for the estimation of the Ep1, based on the sum of atomic orbital spin populations over the carbon atoms in the skeleton of the radical molecule, Σ s(C) AOSPRad, yielded S.E. = 0.063 and S.E.cv = 0.072 on this enlarged set of 29 flavonoids. We also introduced a new complementary model that yielded similar statistics, S.E. = 0.055 and S.E.cv = 0.059. This model was based on the differences in the net atomic charges between cations and neutral flavonoids also summed over the carbon atoms in their skeleton ( Σ s(C) ΔNACCat-Neut). Such an excellent agreement between Σ s(C) ΔNACCat-Neut and Ep1 may be proof that the electrochemical oxidation of all 29 flavonoids starts with ionization, i.e. abstraction of an electron, at both of the pHs indicated.

Orientation and radiation processing of polymeric materials are the main steps in certain modern technologies and have extensive applications. The properties of such treated polymers can change significantly in time and under various exploitation conditions and therefore, investigation of some specific effects of aging and storage of these systems is of great importance, although the overall degradation behavior of iPP is well known. In this work, isotactic polypropylene (iPP) samples were oriented via solid-state stretching at elevated temperature (at 100°C, up to draw ratio λ=20). This was followed by gamma irradiation in the air (up to 700 kGy) and/or thermo-oxidative (TO) aging (in oxygen, at 100°C, up to 8 days) and/or storage (at room temperature, up to 3 years). As the iPP is very sensitive to orientation and degradation, microstructures were analyzed by optical (OM) and scanning electron microscopy (SEM). Wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC) were used to monitor changes in structure and recrystallization. Considering the fact that at higher irradiation doses (>200 kGy), iPP starts to gel under the ambient conditions, gel measurements were employed to determine the yield of network formation induced by irradiation of stretched structures. Irradiation, TO degradation and storage, can induce substantial alternations of (di)electric properties which can be properly connected to the changes in microstructure and crystallinity; therefore, dielectric loss analysis was performed in a wide temperature range and polar groups that were introduced in apolar iPP by oxidation were considered as tracer groups. © 2021 Elsevier Ltd

This article proposes an optimized quantitative model for proportioning concrete mixtures based on cement content, water-cement ratio and percentage of recycled aggregate replacement according to preffered recycled brick aggregate concrete (RBAC) compressive strength. A database compiled from 147 experimental tests of RBAC compressive strength was processed by neural network modelling to achieve a reliable prediction, which was investigated by three-fold validation. The performance of the representative neural network model was verified by parametric analysis with a brief review of the influence of each RBAC component. The focus of the main results is enhancement of the neural network modelling results and consequently new interpretation and conceptualisation for theoretical advancement and practical applied research on RBAC concrete content.

In this work, fast continuously operated microextraction of polyphenolic compounds using ATPSs formed form NADESs and potassium hydrogen phosphate was developed. The effects of the NADES mass, extraction time, extraction temperature, salt concentration and gallic acid concentration on the extraction efficiency have been investigated in batch experiments. Furthermore, a 2D model considering convection in the flow direction and diffusion in two directions at steady-state conditions was developed and the developed extraction method was verified using two realistic samples (aqueous extracts of lemon balm and mint). Using a continuous microextractor, an extraction efficiency of approximately 94% was achieved for a residence time of τ = 3.65 s, which is a significant improvement compared to the batch process where an extraction efficiency of 88% was achieved for a residence time of t = 15 min. Also, the proposed 2D mathematical model described the extraction in a continuously operated micro extractor with high accuracy.

Amino-substituted benzamide derivatives are very attractive compounds due to their capacity to act as powerful antioxidants by scavenging free radicals. Knowledge on electrochemical oxidation mechanisms plays an important role in understanding the free radical scavenging activity of antioxidants. In this paper, the electrochemical oxidation of four amino-substituted derivatives [N-(4-aminophenyl)-2-hydroxybenzamide (1), N-(4-aminophenyl)-2-hydroxy-4-methoxybenzamide (2), N-(4-aminophenyl)-2-methoxybenzamide (3), N-(4-aminophenyl)-3,4,5-trihydroxybenzamide (4)] in an aqueous buffer solution was studied by means of cyclic and square-wave voltammetry, and probable reaction mechanisms have been proposed. In compounds 1–3, the primary amino group was found to be the main electroactive centre undergoing a complex, pH-dependent oxidation process with the transfer of two electrons and two protons. This reaction occurs in one step or in two separate steps, depending on the pH of the medium. A possible explanation for this electrochemical behaviour is discussed. The final products of initial electrochemical oxidation of amino-substituted benzamides 1–3 are quinonediimine derivatives that undergo further chemical transformation into electroactive forms. Oxidation of compound 4 proceeds through two sequential reactions; the first anodic reaction is the oxidation of the trihydroxyphenyl group to the corresponding o-quinone, followed by the oxidation of a primary amino group. Considering the oxidation potentials, and bearing in mind that lower/less positive potential implies better radical scavenging activity, the order of antioxidant activity of the here studied amino-substituted benzamides is: 4 > 2 > 1 > 3.

This paper is a continuation of our studies on the dependence of the first electrochemical oxidation potential, Ep1, on the electronic structures of flavonoids. For this purpose, a set of 20 flavonoids and their cation and radical forms were optimized by semi-empirical PM6 and DFT in water methods. Using differences in net atomic charges ΔNACCat-Neut calculated using PM6 we determined active OH oxygens. DFT in some cases gave different results, which were also in opposition to the literature. The models for the estimation of Ep1 based on the sum of atomic orbital spin populations on carbon atoms in skeleton of radicals, Σ s C AOSPRad, calculated by PM6 method yielded much better statistics than those calculated using DFT (S.E. = 0.064 vs. 0.118).

Polyester fibers gained significant share from all other man-made fibers, but despite numerous advantages a characteristic static electricity generation is still seeking innovative solutions. In order to improve electrical properties of poly(ethyleneterephthalate) (PET) fabric, coating consisting of polyaniline/TiO2 (PANI/TiO2) nanocomposite was deposited on its surface. Coating was synthesized in acidic medium by the chemical oxidative polymerization of aniline with ammonium peroxydisulfate CAPS) in the presence of colloidal TiO2 nanoparticles (d similar to 4.5 nm) and PET fabric. The morphology, molecular structure and dielectric properties of PANI/TiO2 nanocomposites were studied by scanning electron microscopy (SEM), Raman and dielectric spectroscopies. SEM analysis revealed the formation of non-uniform PANI coating on the reference PET sample. In contrast, uniform PANI/TiO2 coating on the surface of PET fabric was generated when TiO2 nanoparticles were engaged. The existence of conductive emeraldine salt form of PANI and phenazine units was confirmed by Raman spectroscopy. Formation mechanisms of PANI and PANI/TiO2 coatings on PET fabrics were proposed. The presence of TiO2 nanoparticles significantly affected the dielectric properties (permittivity and loss tangent) and AC conductivity of PANI/TiO2 coated PET fabrics. PET fabrics coated by PANI/TiO2 nanocomposite showed up to two orders of magnitude higher conductivity in the measured frequency region compared to PANI coated PET fabric. (C) 2015 Elsevier B.V. All tights reserved.

The main objective of this paper is to demonstrate that it is possible to make precast concrete floor blocks with more than 50% replacement of natural aggregate with recycled aggregate made with crushed clay bricks and roof tiles. In first phase of the research, the physico-mechanical properties of concrete with recycled and with natural aggregate were tested. The second phase explored the properties of precast concrete floor blocks. Their geometrical, mechanical, thermal and acoustic properties were determined. Based on experimental research it can be stated that it is possible to make precast concrete floor blocks with recycled aggregate with the fulfilled thermal, cost and environmental requirements.

Various polyethylenes (PEs) and the effects of high-energy radiation on their structures were widely studied in the past using conventional Differential Scanning Calorimetry (DSC) measurements. In this work, we used the Temperature Modulated Differential Scanning Calorimetry (TMDSC) technique in order to obtain more information about the influence of the initial structural differences and gamma radiation on the evolution in structure and thermal properties of different polyethylenes. For this reason, low density polyethylene (LDPE), linear low density polyethylene (LLDPE) and high density polyethylene (HOPE) samples were exposed to gamma radiation, in air, to a wide range of absorbed doses (up to 2400 kGy). The separation of the total heat flow TMDSC signal into a reversing and non-reversing part enabled us to observe the low-temperature enthalpy relaxation (related to the existence of the rigid amorphous phase) and recrystallisation processes, as well as to follow their radiation-induced evolution and/or that of melting in a more revealing manner compared to the case of the conventional DSC. Consequently, our results indicate that TMDSC could improve the understanding of radiation-induced effects in polymers. (C) 2011 Elsevier Ltd. All rights reserved. 12th Tihany Symposium on Radiation Chemistry, Aug 27-Sep 01, 2011, Zalakaros, Hungary

Poly-L-lactide (PLLA) is a well-known biodegradable and biocompatible semi-crystalline polymer, used in a wide variety of applications, from implantable medical devices and drug release matrices to environmentally friendly packaging materials: diversity in the initial preparation, morphology and crystallinity plays a significant role in most of these applications. On the other hand, gamma radiation, as a processing tool, has often been used for the sterilisation of sensitive polymeric materials. This study presents the influence of the initial preparation and crystallinity on the gamma radiation-induced evolution of free radicals in PLLA. For this purpose, PLLA samples with a large variation in crystallinity (below 20% and over 70%), prepared by two different procedures, were exposed to gamma radiation in air to absorbed doses of 25, 50 and 100 kGy. The annealing treatment was applied to part of the samples, too. The presence and evolution of free radicals were followed using electron spin resonance (ESR) spectroscopy for three weeks. Further characterisation was performed by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD) measurements. Presented results show that depending on the initial preparation conditions, the radiation-induced changes in structure and properties of PLLA, as well as the evolution of free radicals, can differ significantly. Furthermore, the annealing treatment substantially reduces the concentration of long-lived free radicals, but can also introduce significant crystallisation. (C) 2011 Elsevier Ltd. All rights reserved. 12th Tihany Symposium on Radiation Chemistry, Aug 27-Sep 01, 2011, Zalakaros, Hungary

We developed two models for the estimation of stability constants in dioxane–water mixtures of mono-complexes of lanthanides (La3+, Ce3+, Pr3+, and Nd3+) with carboxylic acids (ethanoic, propanoic, and butanoic). The first, linear model proved suitable for the prediction of log K1 at low mass fractions of dioxane, w = 0–20% (r = 0.981, S.E. = 0.06), whereas the second, quadratic model, yielded better results at higher fractions, w = 40–60% (r = 0.980, S.E. = 0.10).

The equation for the simultaneous prediction of stability constants at various ionic strengths for copper(II) and nickel(II) mono -complexes with α -amino acids was developed. It is based on valence connectivity index of the 3rd order ( 3 χ v ) and specific ion interaction theory (SIT). The equation was tested on two sets of data. The first set consisted of 31 log K 1 values for copper(II) complexes with four α-amino acids (glycine, alanine, valine and leucine) measured at I = 0–2 mol dm − 3 . The second set encompassed 24 log K 1 values for nickel(II) complexes with seven α-amino acids (glycine, alanine, valine, leucine, 2-aminobutanoic, 2-aminopentanoic and 2-aminohexanoic acid) measured at I = 0–1 mol dm − 3 . Both sets yielded fair agreement with the experiment, with the standard error of estimate 0.09 and 0.10, for the first and the second set, respectively. Moreover, only two log K 1 values in each set were reproduced with an absolute error > 0.2.

Postsystolic contraction and other forms of phenomenon of multiple myocardial contractions are characterised by secondary or even tertiary contraction that follow regular one during each single cardiac cycle, triggered by a single sinus node impulse. These additional contractions occur at circumscribed areas of different myocardial regions, in many cardiac patients and healthy subjects. The mechanism of onset and perpetuation of the phenomenon is unknown. Our hypothesis is based on idea of existence of accessory, dead-end, slow-conducting, low-voltage pathways, derived from atrioventricular node or the bundle of His. Secondary contraction could occur in the following way: sinus node impulse divides into two pathways, the main atrioventricular conduction axis that depolarises the entire myocardium and the accessory pathway that depolarises again target region of myocardium where it ends blindly. Slow conduction through such accessory pathway enables a delay of secondary depolarisation needed to overcome the absolute refractory period of the myocardium following the ‘regular’ contraction. Electrocardiographic signal of a postsystolic potential is not visible at body surface because the pathway is low-voltage. The purpose of multiple myocardial contractions could be, although rarely, completing of current ejection, but more often, in the case of postsystolic contraction it could be a postsystolic tightening of the myocardium which would influence the regular contraction of the next cardiac cycle with the aim to reverse or prevent ventricular remodelling. In those circumstances, regional pathological function of ventricles (deformation of remodelled ventricle during the contraction, maybe during the relaxation as well, and furthermore asynchronous, but otherwise suboptimal contraction as well) would be detected by hypothetical myocardial receptors for strain and stretch, which would activate and sustain the function of accessory dead-end pathways by a neuroendocrine feed-back mechanism. The hypothesis is supported by anatomical findings of dead-end tracts originating from atrioventricular node and disappearing in the muscular part of interventricular septum. Extensive differences in the velocity of impulse propagation, which exist along the conduction system, allow the possibility that the accessory pathways are of slow-conducting properties. Low-amplitude signal of such pathways was confirmed by our intracardiac electrophysiological recording. Feed-back mechanism based on myocardial receptors for strain and stretch is a relevant option, keeping in mind well-known receptor based regulatory mechanisms across the cardiovascular system. The phenomenon is easily detectible, but hard to explain, so even considering herein presented hypothesis implies a need for change of settled perception of myocardial kinetics, and of physiological and pathological function of conducting system.

The high-temperature a relaxation in gamma irradiated isotactic polypropylene (iPP) was studied over the temperature (298-406 K), frequency (10(3)-10(6) Hz) and absorbed dose (0-700 kGy) ranges by means of dielectric spectroscopy. The multiple a relaxation was resolved from the 0 relaxation by curve fitting and its parameters were determined. Its position, intensity and activation energy were found to be strongly dependent on the changes in the structural and morphological parameters attributed to the exposure of the samples to radiation. Wide angle X-ray diffraction (WAXD) was used to investigate radiation-induced changes in the crystalline structure and degree of crystallinity, since this relaxation is connected with the crystal phase. Infrared (IR) spectroscopy and gel measurements were used to determine the changes in the oxidative degradation and the degree of network formation, respectively; the polar (carbonyl and/or hydroperoxide) groups that were introduced by irradiation were considered as tracer groups. Conclusions derived according to different methods were compared. The results reveal uncommon a relaxation behaviour with gamma radiation and confirm the multiple nature of this process, together with high dielectric and/or relaxation sensitivity of iPP to the radiation-induced changes. (C) 2009 Elsevier Ltd. All rights reserved.

The impact of initial conditions on the initiation of ferroresonance is investigated. The investigation is carried out by simulating the behaviour of the model of a 275 kV electromagnetic voltage transformer circuit for a range of practical values of other system parameters. The initial conditions are varied within a practically possible range of initial values of transformer voltage and transformer flux linkage. Additionally, the initiation of ferroresonance is investigated by varying the values of phase angle of voltage source and values of shunt capacitance for the initial values that could appear in two basic cases of ferroresonance initiation.

The estimation of the overall stability constants β 1 of copper(II) and nickel(II) chelates with dipeptides by using the model with the valence connectivity index of the 3rd order (3χ v) was performed by dividing β 1 to their constituting constants K1 and Ka, and subsequently by dividing the basic set into subsets or treating the chelate rings as separate units. Altogether 15 copper(II) and eight nickel(II) chelates with dipeptides were investigated. Six models for the estimation of log K1 and pKa were checked, most of them by usage of indicator variables (for differentiation of copper(II) and nickel(II) complexes or subclasses of ligands). Estimates of log β 1 gave the range of S.E.cv values from 0.19 to 0.27. For the best model errors of estimates were less than 0.34.