Ambiente marinho, sua preservação e relação com o cotidiano : influência de uma exposição interativa sobre as concepções de estudantes do ensino fundamental

O ambiente marinho apresenta grande importância ecológica e econômica, mas, muitas vezes, é negligenciado devido a um aparente distanciamento com nosso cotidiano. Atividades de Educação Ambiental podem ser utilizadas para aproximar os estudantes desse ambiente. Uma delas é a exposição interativa Mergulho Fora D'Água, que foi aplicado em escola da cidade de São Paulo (Brasil). Este estudo de caso verificou as concepções de estudantes que participaram dessa atividade sobre (1) preservação do ambiente marinho e (2) relação desse ambiente com seu cotidiano. Notamos que a maioria dos estudantes não conseguiu relacionar o seu cotidiano ao ambiente marinho, mas considera sua preservação muito importante. Essa concepção muda parcialmente após a exposição, quando uma maior porcentagem de estudantes reconhece a relação cotidiano-ambiente marinho. No entanto, tal relação é predominantemente baseada em uma dimensão antropocêntrica de meio ambiente, ligada à visão de ambiente marinho como recurso a ser utilizado pelo ser humano

Influência de exposição interativa sobre ambiente marinho e sua biodiversidade nas concepções de meio ambiente de estudantes do ensino fundamental

Investigou-se as concepções de meio ambiente de estudantes que participaram de uma exposição sobre ambiente marinho, bem como possíveis modificações nessas concepções após a realização dessa atividade. 423 estudantes (11-15 anos) responderam à questão “O que é meio ambiente?” antes e após a exposição. A maioria apresentou concepção Naturalista, sendo que uma porcentagem reduzida apresentou concepção Globalizante. A diminuição das concepções Antropocêntrica, Conservacionista e Problema representou um aspecto positivo. No entanto, a porcentagem absoluta da categoria Globalizante continuou baixa, evidenciando que a exposição deve agregar novos elementos que auxiliem a promover uma ampliação no perfil de concepções dos estudantes no sentido de incorporar tal aspecto globalizante

Dehydriding and rehydriding reactions of LiBH₄

Structural differences in LiBH₄ before and after the melting reaction at approximately 550 K were investigated to clarify the experimental method for the confirmation of reversible dehydriding and rehydriding reactions. Since the long-range order of LiBH₄ begins to disappear after the melting reaction was achieved, investigation of the atomistic vibrations of the [BH₄]-anion in LiBH₄ was found to be effective for the confirmation of the reversibility. In the present study, LiBH₄ was successively dehydrided (decomposed) into LiH and B under 1 MPa of hydrogen at 873 K, and then rehydrided (recombined) into LiBH₄ under 35 MPa of hydrogen at the same temperature (873 K). The temperatures at the beginning and ending of the dehydriding reaction are lowered, by approximately 30 K, for LiBH₄ substituted (or mixed) with Mg (atomic ratio of Li:Mg=9:1) as compared to those for LiBH₄ alone. This is similar to the tendency exhibited by LiNH₂

First-principles study on the intermediate compounds of LiBH4_4

We report the results of the first-principles calculation on the intermediate compounds of LiBH$_4$. The stability of LiB$_3$H$_8$ and Li$_2$B$_n$H$_n (n=5-12)$ has been examined with the ultrasoft pseudopotential method based on the density functional theory. Theoretical prediction has suggested that monoclinic Li$_2$B$_{12}$H$_{12}$ is the most stable among the candidate materials. We propose the following hydriding/dehydriding process of LiBH$_4$ via this intermediate compound : LiBH$_4 \leftrightarrow {1/12}$Li$_{2}$B$_{12}$H$_{12} + {5/6}$ LiH $+ {13/12}$H$_2 \leftrightarrow$LiH $+$ B $+ {3/2}$H$_2$. The hydrogen content and enthalpy of the first reaction are estimated to be 10 mass% and 56 kJ/mol H$_2$, respectively, and those of the second reaction are 4 mass% and 125 kJ/mol H$_2$. They are in good agreement with experimental results of the thermal desorption spectra of LiBH$_4$. Our calculation has predicted that the bending modes for the $\Gamma$-phonon frequencies of monoclinic Li$_2$B$_{12}$H$_{12}$ are lower than that of LiBH$_4$, while stretching modes are higher. These results are very useful for the experimental search and identification of possible intermediate compounds.Comment: 7 pages, 5 figures, submitted to PR

Arthroscopic Management of Intra-articular Ligament Lesions on Distal Radius Fractures

AbstractArticular distal radius fractures (DRFs) have increased in incidence in recent years, especially among the economically active population. Most of the treatment approaches are based on plain X- rays, and do not give us any information on how to treat these fractures. In the search for solutions with greater precision in diagnosis, in reducing the joint surface of the fracture, and envolving minimally-invasive techniques, we found arthroscopy as the main tool for these patients. Therefore, an enhanced understanding of the biomechanics of the different types of fracture associated with ligamentous lesions should facilitate the right decision regarding the treatment. The present paper aims at providing a management-oriented concept to diagnose and treat ligamentous lesions associated with intra-articular DRFs based on a arthroscopy-assisted procedure, and showing the objective and patient-reported outcomes and a new classification. The objective and patient-reported outcomes were: the mean range of motion (ROM) was of 94.80% on the non-affected side; the mean score on the abbreviated version of the Disabilities of the Arm, Shoulder and Hand questionnaire (QuickDASH) was of 3.6 (range: 1 to 12). The score on the Visual Analog Scale (VAS) was of 1.66 (range: 1 to 3). Complications were observed in 2 (13.33%) patients: extensor tendon synovitis in 1 patient, and a limitation (stiffness) in ROM in 1 patient, both treated with wrist arthroscopy release. The mean time until the return to work was of 6.4 weeks. In patients with unstable intra-articular DRFs associated with ligamentous lesions, the fixation of specific osseous-ligamentous fragments and ligamentous repair/reconstruction by wrist arthroscopy prove to be a safe and reliable treatment. The clinical and functional results predict that the patients can return to work more quickly

Promoting Effect of Cerium Oxide on the Catalytic Performance of Yttrium Oxide for Oxidative Coupling of Methane

The promoting effect of CeO2 on the catalytic performance of Y2O3, which is moderately active catalyst, for the oxidative coupling of methane (OCM) reaction was investigated. The addition of CeO2 into Y2O3 by coprecipitation method caused a significant increase in not only CH4 conversion but also C2 (C2H6/C2H4) selectivity in the OCM reaction. C2 yield at 750 °C was increased from 5.6% on Y2O3 to 10.2% on 3 mol% CeO2/Y2O3. Further increase in the CeO2 loading caused an increase in non-selective oxidation of CH4 to CO2. A good correlation between the catalytic activity for the OCM reaction and the amount of H2 consumption for the reduction of surface/subsurface oxygen species in the H2-TPR profile was observed, suggesting the possibility that highly dispersed CeO2 particles act as catalytically active sites in the OCM reaction. The 16O/18O isotopic exchange reaction suggested that the beneficial role of CeO2 in the OCM reaction is to promote the formation of active oxygen species via the simple hetero-exchange mechanism, resulting in the promotion of CH4 activation