In situ probing of Pt/TiO2_{2} activity in low-temperature ammonia oxidation

The improvement of the low-temperature activity of the supported platinum catalysts in selective ammonia oxidation to nitrogen is still a challenging task. The recent developments in in situ/operando characterization techniques allows to bring new insight into the properties of the systems in correlation with their catalytic activity. In this work, near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and operando X-ray absorption spectroscopy (XAS) techniques were applied to study Pt/TiO$_{2}$ catalysts in ammonia oxidation (NH$_{3}$ + O$_{2}$ reaction). Several synthesis methods were used to obtain samples with different size of Pt particles, oxidation state of Pt, and morphology of the support. Metal platinum particles on titania prepared by pulsed laser ablation in liquids exhibited the highest activity at lower temperatures with the temperature of 50% conversion of NH$_{3}$ being 150 °C. The low-temperature activity of the catalysts synthesized by impregnation can be improved by the reductive pretreatment. NAP-XPS and operando XANES data do not show formation of PtO$_{x}$ surface layers or PtO/PtO$_{2}$ oxides during NH$_{3}$ + O$_{2}$ reaction. Despite the differences in the oxidation state of platinum in the as-prepared catalysts, their treatment in the reaction mixture results in the formation of metallic platinum particles, which can serve as centers for stabilization of the adsorbed oxygen species. Stabilization of the bulk platinum oxide structures in the Pt/TiO$_{2}$ catalysts seems to be less favorable due to the metal–support interaction

Society, State, Nation and the People in the Democratic South Africa: Two Decades of Illusions in The Practice of Public Administration, Development Planning and Management

The purpose of this article is to provide a conceptual argument in that as South Africa transcended beyond its democratic dispensation, an opportunity was missed in the process leading to transition to define a society, state, nation and the people for sustaining the democratic founding for purposes of public administration practice, development planning and management. That is done by critically portraying South Africa as a society, state, nation and locating the people for governance purposes within a democratic founding. It is argued that attempts are made to rewrite the history of the country with a view of bolstering its societal status, nation, state and the people without a profound context. South Africa has become what it is today due to its history that remains its defining factor if it has to locate its society, state, nation and the people. Having lost that opportunity during transition, governance has become so unwieldy in that those assigned with authority in the governance landscape, tend to confuse the roles of society, nation, state and the people and that eventually strain the fragile democracy by distorting the facts and the role of constitutional apparatus that are instrumental to the country’s democratic founding. The conclusion is rather pessimistic in that as long as these issues are not properly located within the governance landscape; the democratic dispensation remains vulnerable for demise just like other democracies within the African continent with the potential of the middle class hijacking it from the vulnerable poor majority being the people that public administration practice has to serve. DOI: 10.5901/mjss.2015.v6n2s1p61

Test-Retest Reliability of Fitness and Skill Tests in Elite Male Youth Basketball Players

Purpose: To assess reliability of fitness and skill tests in elite youth basketball. Players (n=368) from 8 teams in Lithuania (U17 n=25; U16 n=21; U15 n=39; U14 n=57; U13 n=57; U12 n=37; U11 n=70; U10 n=58) completed 2 trials of 4 fitness tests: 20 metre sprint (Sprint); countermovement standing vertical jump (CMJ); standing vertical jump from squat (SVJ); side-step (SST) and two skill tests: ball dribbling (BD); & jump shot (JST), according to Balciunas et al., (2006). Change in mean & 95% confidence intervals, intra-class correlation coefficient, and log-transformed coefficient of variation were calculated (Hopkins, 2000) and correlated with age group. Results: Sprint: Cohort decrease in performance (mean diff .03secs, p<.001, 95% CI .04 & .01, ICCr .92, CV% 2.1); decrease for U17 (mean diff .04secs, p<.05, 95% CI .01 & .08, ICCr .74, CV% 1.9) and U10 (mean diff .06secs, p<.05, 95% CI .11 & .01, ICCr .71, CV% 3.2); ICCr range .71 to .89, CV% range 1.9 to 3.2 across years. CMJ: No cohort difference (mean diff .18cm, 95% IC .61 & -.26, ICCr .87, CV% 11.9) or year groups (mean diff range -.79 to .74cm, ICCr range .46 to .79, CV% 4.2 to 16.5); correlation between increasing age group and CV% (rho -.79, p<.05). SVJ: No cohort difference (mean diff .33cm, 95% CI .71 & -.04, ICCr .86, CV% 11.7); decreased performance for U16 (mean diff -1.44cm, 95% CI -1.6 & -2.73, p<.05, ICCr .70, CV% 6.1) and increased performance for U13 (mean diff .63cm, 95% CI 1.25 & .0, p<.05, ICCr .85, CV% 6.1) and U11 (mean diff 1.13cm, 95% CI 2.08 & .19, p<.05, ICCr .71, CV% 14.1); ICCr range .50 to .85, CV% range 4.7 to 15. SST: Cohort improvement (mean diff -.27secs, 95% CI -.21 & -.33, p.70) except for JSP (ICCr .45). Trends for reduced CV% with increased age group reached statistical significance for the CMJ and SST suggesting increased variability in younger players. Apart from JSP, all tests are reliable for use with elite male youth players

An International Comparative Study of Fitness and Skill in Elite Male U16 Basketball Players

Introduction: Fitness and skill are considered key components of basketball game play and eventual team success, with tests related to key performance indicators (KPI) validated through their ability to discriminate between levels of performance. Purpose: To compare group performance on sport specific fitness tests and KPI-related skill tests in elite male youth basketball players from one high ranked and one low ranked basketball nation. Method: Thirty three male U16-year-old elite and/or national representative players from a high ranked basketball nation (in top five of Division A at the 2005 World Championships, n=16) and a low ranked basketball nation (between 6-10th place in Division B at the 2005 World Championships, n=17) completed four sport specific fitness tests: 20 metre sprint (Sprint); countermovement standing vertical jump (CMJ); standing vertical jump from 90 degree squat (SVJ); Abalakov jump (AJ); and three KPIrelated skill tests: ball dribbling (BD); jump shot (JS); and free throws (FT) using protocols adapted from Balciunas et al., (2006). The best score or time from three attempts was used for group comparison using paired samples t-tests (p<.05). Results: There were no significant group differences found between the Division A and Division B teams for height (1.92±.07m vs 1.86±.09m, p=.07), weight (72.6±5.4kg; Div B 74.2±9.1kg, p=.55), 20m sprint time (3.13±.20secs vs 3.15±.09secs, p=.66), CMJ (40.4±3.1cm vs 40.5±4.8cm, p=.93), SVJ (38.5±3.3cm vs 38.9±4.7cm, p=.79) and BD (7.79±.49secs vs 7.82±.51secs). Significant group differences between the Division A and Division B nations were apparent for BMI (19.8±1.2 kg.m2 vs 21.3±1.3kg.m2, t=3.32, p<.01, eta2=.26), AJ (50.4±3.7cms vs 45.1±5.0cms, t=3.42, p<.01, eta2=.27), JS (12.2±2.7 vs 8.5±3.6, t=3.31, p<.01, eta2=.26) and FT (22.8±3.4 vs 18.8±6.6, t=2.25, p<.05, eta2=.14). Conclusions: As a group, and being similar in positional representation, the higher ranked nation demonstrated a lower weight to height ratio, suggesting a taller and leaner player profile, although more accurate body composition measurement is recommended in future studies. The higher-ranking nation were also found to perform better at arguably the most game specific vertical jump (the Abalakov jump) and the two most ‘score-outcome related’ skill tests. Relative body composition and these three tests may therefore be the most useful for discrimination between levels of performance in elite male youth basketball. Without suggestion of causality, specific physical training and technique/skill practice are recommended for less successful basketball teams in order to improve these seemingly performance related fitness and skill attributes

A study of Pt/al2O3 nanocomposites obtained by pulsed laser ablation to be used as catalysts of oxidation reactions

Pulsed laser ablation (PLA) in liquids is an effective high-energy method for the synthesis of functional nanomaterials. In the present work, a nanocomposite catalyst Pt/Al2O3(PLA) is prepared by mixing solutions of platinum and aluminium nanodispersions obtained by the PLA method in alcohol and water, respectively. After being dried out, the obtained nanocomposite is thermally treated in air at 400 °C and 550 °C. It is shown by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction that platinum in the composition of the calcined samples stabilizes on the Al2O3 surface in the form of metal nanoparticles. The main crystal structure of η-Al2O3 is determined and impurity phases of Al(OH)3 hydroxide and metallic aluminium are revealed using X-ray powder diffraction (XRPD). The Pt/Al2O3 nanocomposite samples obtained by the PLA method are found to be highly prospective for the use in reactions of catalytic oxidation of CO and NH3. The Pt/Al2O3(PLA) nanocomposites are compared with the Pt/Al2O3 (IMP) catalyst synthesized by the method of solution chemistry. The Pt/Al2O3(IMP) sample containing highly dispersed platinum nanoparticles (1–2 nm) on the γ-Al2O3 surface has a lower T50 value (188 °C) in the reaction of CO oxidation that the PLA catalyst (T50 = 198 °C). At the same time, in the reaction of NH3 oxidation, the PLA catalyst is more active (T50 = 167 °C) than the IMP sample (T50 = 180 °C). The observed regularities are discussed in terms of the dispersion and the oxidation depth of platinum particles in the composition of Pt/Al2O3 catalysts

Unraveling the low-temperature activity of Rh-CeO2 catalysts in CO oxidation: probing the local structure and Red-Ox transformation of Rh3+ species

The local structure of the active sites is one of the key aspects of establishing the nature of the catalytic activity of the systems. In this work, a detailed structural investigation of the Rh-CeO2 catalysts prepared by the co-precipitation method was carried out. The application of a variety of physicochemical methods such as XRD, Raman spectroscopy, XPS, TEM, TPR-H2, and XAS revealed the presence of highly dispersed Rh3+ species in the catalysts: Rh3+ single ions and RhOx clusters. The substitution of Ce4+ ions by Rh3+ species, which provided a strong distortion of the CeO2 lattice, is shown. XAS data ensured the refinement of the Rh local structure. It was shown that single Rh3+ sites located next to each other can merge the formation of RhOx clusters with Rh local environment close to the one in Rh2O3 and CeRh2O5 oxides. The distortion of the CeO2 lattice around single and cluster rhodium species had a beneficial effect on the catalytic activity of the samples in low-temperature CO oxidation (LTO-CO). TEM, XAS, and in situ XRD data allowed establishing the structural transformations of the catalysts under Red-Ox treatments. The reduction treatment led to Rhn metallic cluster formation localized on defects of the reduced CeO2−δ. The reduced sample demonstrated efficient CO conversion at 0 °C. However, this system was not stable: its contact with air led to ceria reoxidation and partial reoxidation of Rh to highly dispersed Rh3+ species at room temperature, while heating in an oxidizing atmosphere resulted in the complete reoxidation of metallic rhodium species. The results of the work shed light on the structural aspects of the reversibility of the Rh-CeO2 catalysts based on the highly dispersed Rh3+ species under treatment in the reaction conditions