Sonolytic, photocatalytic and sonophotocatalytic degradation of malachite green in aqueous solutions

Summarization: The degradation of malachite green (MG) in water by means of ultrasound irradiation and its combination with heterogeneous (TiO2) and homogeneous photocatalysis (photo-Fenton) was investigated. Emphasis was given on the effect of key operating conditions on MG conversion and mineralization rates and the elucidation of major reaction by-products. Eighty-kilohertz of ultrasound irradiation was provided by a horn-type sonicator, while a 9 W lamp was used for UV-A irradiation. The extent of sonolytic degradation increased with increasing ultrasound power (in the range 75–135 W) and decreasing initial concentration (in the range 2.5–12.5 mg L−1), while the presence of TiO2 in the dark generally had little effect on degradation. Sonolysis under argon was substantially faster than under air, oxygen or helium leading to complete MG degradation after 120 min at 10 mg L−1 initial concentration and 135 W ultrasound power. On the other hand, TiO2 photocatalysis or photo-Fenton led to complete MG degradation in 15–60 min with the rate increasing with increasing catalyst loading (in the range 0.1–0.5 g L−1 for TiO2 and 7–20 mg L−1 for Fe3+) and also depending on the gas used. TiO2 sonophotocatalysis was always faster than the respective individual processes due to the enhanced formation of reactive radicals as well as the possible ultrasound-induced increase of the active surface area of the catalyst. For instance, the pseudo-first order rate constant for the sonophotocatalytic degradation at 0.5 mg L−1 TiO2 under air was 136.7 × 10−3 min−1 with the respective values for photocatalysis and sonolysis being 112.6 × 10−3 and 11.6 × 10−3 min−1. Irrespective of the process employed, mineralization was slower than MG decomposition implying the formation of stable by-products accompanied by the release of nitrates in the solution. GC/MS analysis verified the identity of primary intermediates and a reaction pathway based on them was proposed. Depending on the conditions employed, ecotoxicity of MG to marine bacteria was partly or fully eliminated.Παρουσιάστηκε στο: Applied Catalysis B: Environmenta

Plyometrics trainability in preadolescent soccer athletes

Michailidis, Y, Fatouros, IG, Primpa, E, Michailidis, C, Avloniti, A, Chatzinikolaou, A, Barbero-Alvarez, JC, Tsoukas, D, Douroudos, II, Draganidis, D, Leontsini, D, Margonis, K, Berberidou, F, and Kambas, A. Plyometrics' trainability in preadolescent soccer athletes. J Strength Cond Res 27(1): 38-49, 2013-Plyometric training (PT) is a widely used method to improve muscle ability to generate explosive power. This study aimed to determine whether preadolescent boys exhibit plyometric trainability or not. Forty-five children were randomly assigned to either a control (CG, N = 21, 10.6 6 0.5 years; participated only in regular soccer practice) or a plyometric training group (PTG, N = 24, 10.6 6 0.6 years; participated in regular soccer practice plus a plyometric exercise protocol). Both groups trained for 12 weeks during the in-season period. The PT exercises (forward hopping, lateral hopping, shuffles, skipping, ladder drills, skipping, box jumps, low-intensity depth jumps) were performed twice a week. Preadolescence was verified by measuring Tanner stages, bone age, and serum testosterone. Speed (0-10, 10- 20, 20-30 m), leg muscle power (static jumping, countermovement jumping, depth jumping [DJ], standing long jump [SLJ], multiple 5-bound hopping [MB5]), leg strength (10 repetition maximum), anaerobic power (Wingate testing), and soccerspecific performance (agility, kicking distance) were measured at baseline, midtraining, and posttraining. The CG caused only a modest (1.2-1.8%) increase in speed posttraining. The PTG induced a marked (p , 0.05) improvement in all speed tests (1.9-3.1% at midtraining and 3-5% at posttraining) and vertical jump tests (10-18.5% at midtraining and 16-23% at posttraining),SLJ (2.6% at midtraining and 4.2% at posttraining), MB5 (14.6% at midtraining and 23% at posttraining), leg strength (15% at midtraining and 28% at posttraining), agility (5% at midtraining and 23% at posttraining), and kicking distance (13.6% at midtraining and 22.5% at posttraining). Anaerobic power remained unaffected in both groups. These data indicate that (a) prepubertal boys exhibit considerable plyometric trainability, and (b) when soccer practice is supplemented with a PT protocol, it leads to greater performance gains. © 2013 National Strength and Conditioning Association