Dimorfismo funcional y relación entre diferentes test de fuerza de extremidades inferiores en jóvenes judokas de élite

[ES] El presente estudio investigó el índice de simetría de las extremidades (LSI) y la relación entre diferentes pruebas de fuerza funcional en jóvenes judokas de élite. Diecisiete varones (edad=16,88±1,40 años, altura=179,00±7,00 cm, peso=78,76±15,22 kge IMC24,40±3,36 kg/m2) participaron voluntariamente en el estudio. Los participantes fueron evaluados mediante el single hop test(SL), triple hop test(THD),crossover hop test (CHD),6-m hop test (6mTHT) y test de salto vertical a una pierna(SLVJ) y salto con contra movimiento (CMJ). Todos los SL hop test (SLHT) se aplicaron tanto en la pierna derecha (Rs) como en la izquierda (Ls), mientras que el CMJ se aplicó sin(CMJWAS) y con balanceo de brazos (CMJAS). En los análisis estadísticos se utilizaron -test de muestras pareadas y test de correlación de Pearson. En todos los SLHT no se encontraron diferencias significativas entre la entre ambas extremidades. Sin embargo, se encontraron diferencias entre el CMJWAS y el CMJAS. Tampoco hubo diferencias en los LSI entre todos los SLHT. Se encontraron correlaciones entre los test SL, THD, CHD, VJ, y se encontraron correlaciones negativas y significativas en los test SL, THD,CHD, VJ y THT 6 m. No se encontraron diferencias en los test SLHT y CMJWAS y CMJAS. En consecuencia, se encontró que las extremidades inferiores de los jóvenes judokas producían una fuerza similar en los SLHT, y se encontró que había diferencias en los valores de CMJWAS y CMJAS; cuando se evaluó en términos del LSI, los judokas mostraron tasas similares en todos los SLHT, y estas tasas estaban dentro de rangos fiables; los SLHT tenían correlaciones entre sí, pero no mostraron ninguna correlación con el CMJ.[EN] The present study investigated the limb symmetry index (LSI) and the relationship between different functional strengthtests in young elite judokas. Seventeen males (age= 16.88±1.40 years, height= 179.00±7.00 cm, weight= 78.76±15.22 kgand BMI 24.40±3.36 kg/m2) participated in the study voluntarily. Participants were tested with single leg (SL), and triple leg (THD) hop for distance, crossover hop for distance (CHD), 6 m Timed Hop Test(6mTHT), and single-leg vertical jump(SLVJ) tests, and counter movement jump (CMJ). All SL hop tests (SLHT) were applied to both right (Rs) and left sides(Ls), while CMJ was applied as without (CMJWAS) and with arm swing (CMJAS). Paired sample t-test and Pearson correlation tests were used in statistical analyses. In all SLHTs, no statistical significance was found between Rs and Ls. However, significance was found between CMJWAS and CMJAS. There was also no significance in LSIs between all SLHTs. Correlations were found between SL, THD, CHD, VJ tests, while negative and significant correlations were found between SL, THD, CHD, VJ tests, and 6 m THT. No significance was found between SLHTs and CMJWAS and CMJAS. As a result, it was found that Rs and Ls of young judokas produced similar strength in SLHTs, while they caused differences in CMJWAS andCMJAS values; when evaluated in terms of LSI, judokas showed similar rates in all SLHTs, and these rates were with inreliable ranges; SLHTs had correlations with each other, but they did not show any correlation with CMJ.[PT] O presente estudo investigou o índice de simetria dos membros superiores e inferiores (IEL) e a relação entre diferentes testes de força funcional em jovens judocas de elite. Dezassete indivíduos (idade= 16,88 ± 1,40 anos;altura= 179,00 ± 7,00 cm; peso= 78,76 ± 15,22 kg; e IMC 24,40 ± 3,36 kg/m2) participaram voluntariamente no estudo. Foram avaliados por meio de vários testes: single hop test (SL), triple hop test (THD), crossover hop test(CHD), 6-m hop test (6mTHT), salto vertical de perna única (SLVJ) e salto com contra movimento (CMJ). Todos osSLhop test (SLHT) foram aplicados, tanto na perna direita (Rs), como na perna esquerda (Ls), en quanto o CMJ foi aplicado sem (CMJWAS) e com braço swing (CMJAS). O t-testde amostras emparelhadas e o teste de correlação de Pearson foram usados nas análises estatísticas. Em todos os SLHTs, não foram encontradas diferenças significativas entre as duas extremidades. No en tanto, foram encontradas diferenças entre CMJWAS e CMJAS. Também não houve diferenças no LSI entre todos os SLHTs. Foram encontradas correlações entre os testes SL, THD, CHD, VJ, e correlações negativas e significativas foram encontradas nos testes SL, THD, CHD, VJ e THT 6 m. Nenhuma diferença foi encontrada nos testes SLHT e CMJWASe CMJAS Consequentemente, verificou-se que os membros inferiores dos jovens judocas produziram uma força semelhante no SLHT, enquanto ocorreram diferenças nos valores de CMJWAS e CMJAS. Quando avaliados em termos de LSI, os judocas mostraram taxas semelhantes em todos os SLHTs, e essas taxas estavam dentro dos intervalos de confiança. Os SLHTs foram correlacionados entre si, mas não apresentaram correlação com o CMJ

Novel Approach for Synthesis of Magnesium Borohydride, Mg(BH4)2

AbstractMg(BH4)2 is a complex hydride with one of the highest hydrogen contents (∼ 15%) known yet. Several synthesis routes have been reported for it, all based on the metathesis reaction of MgCl2 with NaBH4 performed in a ball-mill or in suitable solvents.In the present study a new approach for synthesis of Mg(BH4)2 will be presented in which the more reactive MgBr2 is used instead of MgCl2. For this purpose a mixture of MgBr2 and NaBH4 (molar ratio: 1: 2 and 1:2.15) was ball-milled for 6, 12 and 18h, respectively. Mg(BH4)2 was extracted from the reaction product (Mg(BH4)2 + NaBr) by Soxhlet with diethylether over a day. The remaining residue after solvent evaporation was dried in vacuum at 150°C for 24h and 5h at 190°C. The intermediate and final products of the reactions were analyzed using XRD, DTA/TG, Mass and Vibrational Spectroscopy. The XRD diagrams of the mixture after ball milling showed only the characteristic reflections of NaBr and the patterns obtained after solvent extraction was in all cases consistent with β- Mg(BH4)2. The additional weak MgBr2 reflections, decreased by increasing the ball milling time from 6 to 18h. The DTA/TG coupled with MS revealed ∼11% mass loss when the product was heated up to 600°C. The result of MS detected that the exhaust gas is exclusively H2.Compared to MgCl2, the use of MgBr2 has two advantages: the reaction time is considerably shorter and the excess of MgBr2 can act as additive lowering the onset temperature for hydrogen release from 290°C - for pure Mg(BH4)2 - to ∼ 220°C

Approximation properties of two dimensional Bernstein-Stancu-Chlodowsky operators

In this paper, as a generalization of Bernstein-Stancu type operators of two variable, we introduce a new positive linear operator called Bernstein-Stancu-Chlodowsky on a triangular domain, with mobile boundaries, which extends to [0, ∞) × [0, ∞) as n → ∞. We give some shape properties that are preserved and also obtain weighted approximation properties of these operators