Controlled synthesis of CoFe2O4 nano-octahedra

International audienceNano-octahedral grains of cobalt ferrite (CoFe2O4) with size around 20 nm were synthesized by a hydrothermal route. X-rays and electron diffraction, along with scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy and thermogravimetric analysis were used to characterize the powders. Images and simulations of high-resolution electron microscopy allowed the identification of the shape of the grains. Process parameters such as temperature and time of reaction, reagents concentration, and pH of the reacting medium were optimized. The surfactant cetyltrimethylammonium bromide (CTAB) hindered the formation of goethite, which favored the production of a pure CoFe2O4 powder. The oxidation state of cobalt atoms on the ferrite structure was also influenced by CTAB. The control of the shape of the grains was associated mainly to the nature of the precipitating agent

How does 11-week detraining affect 11-12 years old swimmers’ biomechanical determinants and its relationship with 100 m freestyle performance?

The aim of this study was to analyse the detraining process that occurs during a season break, and its influence on the performance, anthropometrics, and biomechanics of young swimmers. The sample included 54 young swimmers (22 boys: 12.79 +/- 0.71 years; 32 girls: 11.78 +/- 0.85 years). Performance for the 100 m freestyle and anthropometric and biomechanical variables were evaluated as main determinants. Performance impaired significantly for boys (2.17%) and girls (1.91%). All anthropometric variables increased between moments of assessment for boys and girls. Overall, the boys enhanced all biomechanical variables during the detraining period, and girls showed mixed results. For both sexes, the stroke index was the variable with the highest increase (boys: Delta = 16.16%; d = 0.89; p = 0.001; girls: Delta = 19.51%; d = 1.06; p = 0.002). Hierarchical linear modelling showed that the height retained the amount of impairment in the performance. One unit of increase in the height (cm) led to less 0.41 s impairment in the performance. Present data indicated that during an 11-weeks detraining period, young swimmers impaired their performance, but the determinant factors showed an impaired relationship. This increase in the determinant factors is mainly related to the increase in the swimmers' anthropometrics. Moreover, the increase in height was responsible for retaining the performance impairment.This project was supported by National Funds through FCT -Portuguese Foundation for Science and Technology (UID/DTP/04045/2019), and the European Fund for regional development (FEDER) allocated by the European Union through the COMPETE 2020 Programme (POCI01-0145-FEDER-006969).info:eu-repo/semantics/publishedVersio

Comparison of swimming velocity between age-group swimmers through discrete variables and continuous variables by Statistical Parametric Mapping

The aim of this study was to compare the swimming velocity in frontcrawl between age-group swimmers using discrete variables against Statistical Parametric Mapping (SPM). The sample consisted of 30 young male swimmers divided into three groups (each with 10 swimmers) based on their age (group #1: 13.60 ± 0.84 years; group #2: 15.40 ± 0.32 years; group 3: 16.39 ± 0.69 years). Swimmers performed three maximal trials in front-crawl. The best performance was used for analysis. Comparison of swimming velocity between groups was analysed using discrete variables and as a continuous variable (SPM). As a discrete variable, the mean swimming velocity showed a significant difference between groups (p < 0.05). Moreover, when analysed by SPM, swimming velocity showed a significant difference (p = 0.021) between the ~ 44% and ~ 51% of the stroke cycle (transition of the propulsion phases between sides). Post-hoc comparison revealed a significant difference between group #1 and group #3 only in SPM analysis. Researchers, coaches, and practitioners should know that both measurement approaches can be used simultaneously. However, SPM offers more sensitive and accurate results about the swimmers’ stroke cycle.This work is supported by national funds (FCT – Portuguese Foundation for Science and Technology) under the project [UIDB/DTP/04045/2020]info:eu-repo/semantics/publishedVersio

Estudo de obtenção da membrana cerâmica densa BaCeO3

Nos últimos anos, pós cerâmicos à base de óxidos de estrutura do tipo perovskita ganharam atenção consideráveldevido às suas aplicações tecnológicas na área de membranas permeáveis de oxigênio. O óxido mistoBaCeO3 apesenta-se como um material amplamente estudado em uma grande diversidade de aplicações, sejacomo materiais eletrolíticos em células a combustível, ou mesmo como catalisadores nas reações de catálise.Dessa forma, o presente trabalho teve como objetivo sintetizar a fase BaCeO3, pelo método de coprecipitaçãoem meio oxalato, verificando o efeito da sinterização com diferentes aglutinantes na estabilidade térmica edensificação da membrana. A técnica de coprecipitação em meio oxalato mostrou-se eficaz na obtenção daperovskita BaCeO3. As amostras obtidas durante as sínteses foram caracterizadas por difração de raios-x,observando-se a formação da fase ortorrômbica da perovskita BaCeO3. Para determinar o tamanho médio decristalito foi utilizada a equação de Scherrer e de Williamson Hall, chegando-se a um valor próximo a de 107nm. Conforme a literatura [1,2] e diante dos resultados apresentados definiu-se como condições favoráveispara formação de material com o menor tamanho de cristalito e maior pureza da fase formada, a amostra depH 13 e de temperatura de calcinação de 1000 ºC. Através da microscopia eletrônica de varredura (MEV)pode-se observar a formação de cristais homogêneos. Por fim, foi possível observar que a sinterização napresença dos aglutinantes parafina e álcool polivinílico a 1300 ºC com patamar de 5 h, permitiu a obtenção depastilhas densas com bons níveis de retração, possuindo estabilidade térmica ideal para serem utilizadas comomembranas permeáveis de oxigênio e como eletrólito de células a combustível.Palavras-chave: BaCeO3; Coprecipitação em meio oxalato; Sinterização; Membrana; Permeação de oxigênio

Motor Learning and Virtual Reality in Down Syndrome; a Literature Review

 Down syndrome (DS) is caused by trisomy of human chromosome 21 (Hsa21) and results in a large number of phenotypes including learning difficulties, cardiac defects and distinguishing facial features. The purpose of this study was to analyse research findings about “motor learning†and “virtual reality†in patients with DS. Relevant studies were identified by searching PubMed, Web of Science and BVS. Using key words, we searched for articles that included Down syndrome, virtual reality, and motor learning. Only studies on humans were eligible. The search  identified seven relevant papers. Most studies showed that individuals with Down syndrome are able to learn new tasks, and that improvements can be enhanced via the use of virtual reality. We conclude that individuals with Down syndrome respond positively and effectively, with improvements in sensory motor control, when stimulated with tasks that are complementary to conventional therapy, including therapy involving virtual reality

Otimização da adsorção do Erionyl Yellow A-R em carvão ativado do bagaço da cana-de-açúcar por meio de planejamento experimental / Optimization of the adsorption of Erionyl Yellow A-R on activated charcoal from sugarcane bagasse using design of experiments

Os corantes sintéticos apresentam uma grande aplicabilidade em diversos segmentos da indústria. Na indústria têxtil, devido às ineficiências nos processos de tingimento, 200.000 toneladas por ano desses produtos passam para o efluente industrial, sendo parte dele despejada no meio ambiente sem tratamento prévio. Quando lançados em corpos hídricos, mesmo em pequenas concentrações, os corantes podem afetar o processo de fotossíntese dos organismos presentes, devido à diminuição da penetração solar, causando um desequilíbrio no ecossistema. Dessa forma, se faz necessária a realização de um método de tratamento capaz de remover esses compostos.  No caso dos corantes solúveis, os processos envolvendo adsorção se mostram eficazes em sua remoção. Com isso, este trabalho tem como objetivo produzir e caracterizar carvão ativado obtido a partir do bagaço de cana-de-açúcar, determinar sua eficiência no processo de adsorção do corante Erionyl Yellow A-R, bem como utilizar técnicas estatísticas com a finalidade de avaliar e otimizar os diferentes parâmetros do processo de adsorção desse corante no carvão ativado. O resultado das caracterizações do adsorvente mostrou grande presença de microporos, resultando numa área específica superior a 1200 m²g. Os ensaios de adsorção foram realizados variando-se o pH e a temperatura do meio. Através dos dados obtidos estatisticamente, verificou-se que as variáveis estudadas apresentaram efeitos significativos, dentro da faixa de níveis experimentais estudada, extrapolando a linha de referência correspondente ao intervalo de confiança de 95%. Verificou-se também que o ensaio a 30 °C e pH 2 obteve a maior quantidade de corante adsorvido pelo carvão ativado (q), atingindo um valor de 61,1 mg/g. 

Superpulsed low-level laser therapy protects skeletal muscle of mdx mice against damage, inflammation and morphological changes delaying dystrophy progression.

Aim: To evaluate the effects of preventive treatment with low-level laser therapy (LLLT) on progression of dystrophy in mdx mice. Methods: Ten animals were randomly divided into 2 experimental groups treated with superpulsed LLLT (904 nm, 15 mW, 700 Hz, 1 J) or placebo-LLLT at one point overlying the tibialis anterior muscle (bilaterally) 5 times per week for 14 weeks (from 6th to 20th week of age). Morphological changes, creatine kinase (CK) activity and mRNA gene expression were assessed in animals at 20th week of age. Results: Animals treated with LLLT showed very few morphological changes in skeletal muscle, with less atrophy and fibrosis than animals treated with placebo-LLLT. CK was significantly lower (p = 0.0203) in animals treated with LLLT (864.70 U.l−1, SEM 226.10) than placebo (1708.00 U.l−1, SEM 184.60). mRNA gene expression of inflammatory markers was significantly decreased by treatment with LLLT (p<0.05): TNF-α (placebo-control = 0.51 µg/µl [SEM 0.12], - LLLT = 0.048 µg/µl [SEM 0.01]), IL-1β (placebo-control = 2.292 µg/µl [SEM 0.74], - LLLT = 0.12 µg/µl [SEM 0.03]), IL-6 (placebo-control = 3.946 µg/µl [SEM 0.98], - LLLT = 0.854 µg/µl [SEM 0.33]), IL-10 (placebo-control = 1.116 µg/µl [SEM 0.22], - LLLT = 0.352 µg/µl [SEM 0.15]), and COX-2 (placebo-control = 4.984 µg/µl [SEM 1.18], LLLT = 1.470 µg/µl [SEM 0.73]). Conclusion: Irradiation of superpulsed LLLT on successive days five times per week for 14 weeks decreased morphological changes, skeletal muscle damage and inflammation in mdx mice. This indicates that LLLT has potential to decrease progression of Duchenne muscular dystrophy

Effect of thermal parameters and pH on obtaining copper ferrite via EDTA-Citrate complexation method

The synthesis of ceramic materials such as ferrite has been widely studied in recent years, due to their properties that make these materials have excellent applications in technology, as well as in photocatalytic processes and as catalysts. To obtain the copper ferrite phase the EDTA-Citrate complexation method was used, varying pH (5, 7 and 9), temperature (600, 800 and 1000 °C) and calcination time (2, 7 and 12 h). Composition, morphology and structural analyzes were performed by X-ray fluorescence spectroscopy, X-ray dispersive energy, scanning electron microscopy and X-ray diffraction, respectively. Crystalline phase of copper ferrite (CuFe2O4) with tetragonal structure and secondary phase of Fe2O3 and CuO was verified by XRD analysis. Regarding the chemical composition analyzes, percentage deviations of the samples and the theoretical value for copper and iron were calculated. It was obtained minimum values of 0.16 - 0.08% (atomic%, EDS) and 16 - 8% (atomic%, XRF) in relation to copper and iron, respectively, for the sample obtained under pH 9, calcined at 600 °C for 12 h. The variation of the synthesis condition via EDTA-Citrate directly influenced the morphology of copper ferrite, presenting agglomerated particles, pore formation, irregular spheres, and even powder sintering.keywords: thermal parameters, pH, copper ferrite, EDTA-Citrate, crystallinity and morphology.

An experimental study of low-level laser therapy in rat Achilles tendon injury

The aim of this controlled animal study was to investigate the effect of low-level laser therapy (LLLT) administered 30 min after injury to the Achilles tendon. The study animals comprised 16 Sprague Dawley male rats divided in two groups. The right Achilles tendons were injured by blunt trauma using a mini guillotine, and were treated with LLLT or placebo LLLT 30 min later. The injury and LLLT procedures were then repeated 15 hours later on the same tendon. One group received active LLLT (λ = 904 nm, 60 mW mean output power, 0.158 W/cm2 for 50 s, energy 3 J) and the other group received placebo LLLT 23 hours after LLLT. Ultrasonographic images were taken to measure the thickness of the right and left Achilles tendons. Animals were then killed, and all Achilles tendons were tested for ultimate tensile strength (UTS). All analyses were performed by blinded observers. There was a significant increase in tendon thickness in the active LLLT group when compared with the placebo group (p < 0.05) and there were no significant differences between the placebo and uninjured left tendons. There were no significant differences in UTS between laser-treated, placebo-treated and uninjured tendons. Laser irradiation of the Achilles tendon at 0.158 W/cm2 for 50 s (3 J) administered within the first 30 min after blunt trauma, and repeated after 15 h, appears to lead to edema of the tendon measured 23 hours after LLLT. The guillotine blunt trauma model seems suitable for inflicting tendon injury and measuring the effects of treatment on edema by ultrasonography and UTS. More studies are needed to further refine this model