In this study, modified sol-gel method was employed to synthesize the pure and Zr-doped titania catalysts. Brunauer-Emmett-Teller (BET) method was applied to determine porosity, X-ray diffraction (XRD) analysis was used to study crystal structure, scanning electron microscopy (SEM) was used to investigate morphology and Fourier transform infrared spectroscopy (FTIR) was used to examine surface properties/total acidity of the obtained catalysts samples. Photocatalytic activity was tested in the reaction of crystal violet (CV) dye decolourization/degradation under UV light irradiation. The effects of several photocatalysis operational parameters were considered, such as catalyst dosage, initial dye concentrations, duration of UV irradiation treatment, as well as catalysts calcination temperatures and dopant amounts. The obtained results indicated faster dye decolourization/degradation with the increase of the catalyst dosage and the decrease of initial CV concentrations. The Zr-doping affects photocatalytic properties, i.e. CV decolourization/degradation of the prepared catalytic materials. Thus, addition of 5 wt.% of ZrO 2 to titania increases photocatalytic effect for ∼15% and addition of 10 wt.% of ZrO 2 improves the photocatalytic efficiency of titania for nearly 30%.

The purpose of this experimental study was to determine the effects of a skill-based exercise program on the body composition of adolescents. The study was conducted on 90 participants, (age, 13±6 years), divided by gender then randomly assigned into two sub-samples: the experimental [SS1, N=39 (EG1, 19 girls and EG2, 20 boys)] and the control group [SS2, N=51 (CG1, 24 girls and CG2, 27 boys)]. Body composition parameters were assessed by a caliper (skinfold thickness) and bioelectrical impedance analyzer Omron BF511 (percentage of body fat tissue and muscle tissue). After conducting the 16-week program of skill-based exercises and small-sided games (SSG) related to volleyball, certain body composition parameters statistically significantly increased in the experimental groups (except body fat percent in girls, and body fat mass in both genders). In the experimental period, the SS2 increased in body fat tissue (both genders) and in muscle tissue (girls), while a decrease in muscle tissue was recorded among the boys. The results of this study showed no significant differences in the effects of the two programs on body composition at the multivariate level for both genders. Furthermore, at the univariate level it was noted that the students following the experimental program (SS1) had better results compared to the SS2 of students in terms of the decrease of body fat tissue, as well as the increase of muscle tissue for both genders. The obtained results indicate that the program of skill-based exercises and SSG related to volleyball is suitable for adequate intensification of PE classes and improvement of body composition parameters of elementary school students.

Resorcinol-formaldehyde carbon cryogel has been prepared, characterized and used for the removal of commonly used herbicide clopyralid from the aqueous solutions under varying experimental conditions. Carbon has shown a relatively high specific surface area, significant mesoporosity and an amorphous structure. A set of the following isotherm models has been used to interpret the equilibrium data: Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Jovanovic, Hurkins-Jura, and Helsey model. Several models have fitted well although the calculated values for qmax poorly correlate with the data obtained experimentally. The kinetic models of the pseudo-first and pseudo-second-order, the models of Elovich, Bangham and the intraparticle diffusion model have been used for fitting the kinetic data. The rate of the process is fast in the beginning while adsorption equilibrium is attained not until 24 hours. Adsorption was found to be pH dependent and favored in acidic solutions.

Bentonite is mainly composed of clay minerals from smectite group, therefore it has a well developed and chemically active surface area and high cation exchange capacity. Moreover, an interlayer space of smectite has unusual hydration properties, which manifest as swelling of bentonite in water. These properties make bentonite as a commonly used raw material in chemistry and industry, and it is very important in environmental protection and water treatment as an effective sorbent of heavy metals. The results of X-ray diffraction, a cationic exchange capacity, specific surface area, acid-base properties of the surface and the swelling index showed that the bentonite sample contains mostly montmorillonite. The aim of this study was to test the efficacy of bentonite in the removal of Mn2+ from aqueous systems. The experimental results of Mn2+ adsorption on the bentonite were interpreted by Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherms. The adsorption isotherm studies indicate that the adsorption of Mn2+ follows Langmuir isotherm very well. Theoretical monolayer saturation capacity according to Langmuir model was 12.41 mg/g. The removal of Mn2+ is achieved by ion exchange mechanism with naturally occurring cations in bentonite, as well as by forming the inner- and outer-sphere complexes with bentonite surface

TThe aim of this paper was to examine the differences in the motor skills of soccer players aged 16-18 years who play in different competition levels (National League and Regional League), as well as players who play in different positions in the team. The standard testing battery for the motor skills assessment of soccer players was used to evaluate the motor skills. As for the evaluation of the differences between the different playing positions, a two-factor ANOVA with the factor Competition Level (National and Regional Level) and the factor Position (forward, midfielder, side defender, central defender) was used. A two-factor ANOVA with the factor Competition Level (National and Regional Level) and the factor Age (16, 17 and 18 years of age) was used to evaluate the differences between the different quality levels. The study included 126 male soccer players 16 to 18 years of age (N16=45, N17=41, N18=40) divided into 4 positions on the team: forwards (N=37, BH=179.2±5.0, BM=70.1±6.6), midfielders (N=48, BH=177.9±6.3, BM=69.6±7.9), side defenders (N=22, BH=176.6±5.4, BM=67.5±5.7) and central defenders (N=19, BH=184.0±4.3, BM=72.3±6.6). Because of significantly different activities in the field, the goalkeeper position was excluded from this study. The results indicate that motor skills do not differentiate players of different competition levels, and that there is a gap between players aged 18 years in aerobic endurance which is the basis of success in soccer.  Also, the obtained results suggest that motor skills could differentiate players at certain positions. However, it was specifically found that only alactic capabilities type of speed and agility, differentiate forwards from other positions, especially from midfielders.