The first observed stellar occultations by the irregular satellite Phoebe (Saturn IX) and improved rotational period

peer reviewedWe report six stellar occultations by Phoebe (Saturn IX), an irregular satellite of Saturn, obtained between mid-2017 and mid-2019. The 2017 July 6 event was the first stellar occultation by an irregular satellite ever observed. The occultation chords were compared to a 3D shape model of the satellite obtained from Cassini observations. The rotation period available in the literature led to a sub-observer point at the moment of the observed occultations where the chords could not fit the 3D model. A procedure was developed to identify the correct sub-observer longitude. It allowed us to obtain the rotation period with improved precision compared to the currently known value from literature. We show that the difference between the observed and the predicted sub-observer longitude suggests two possible solutions for the rotation period. By comparing these values with recently observed rotational light curves and single- chord stellar occultations, we can identify the best solution for Phoebe's rotational period as 9.27365 ± 0.00002 h. From the stellar occultations, we also obtained six geocentric astrometric positions in the ICRS as realized by the Gaia DR2 with uncertainties at the 1-mas level

A Multimethod Assessment of a New Customized Heat-Treated Nickel–Titanium Rotary File System

Funding Information: Funding was provided by CENIMAT/i3N through national funds obtained through the FCT-Fundação para a Ciência e a Tecnologia, I.P., within the scope of Multiannual Financing of R&D Units, reference UIDB/50025/2020-2023, and is acknowledged by F.M.B.F. Fernanda Carvalho is acknowledged for running the DSC tests of the files. This study was also partly funded by the Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), reference E-26/201.249/2021 and by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), reference 403655/2021-8. Publisher Copyright: © 2022 by the authors.This study aimed to compare three endodontic rotary systems. The new Genius Proflex (25/0.04), Vortex Blue (25/0.04), and TruNatomy (26/0.04v) instruments (n = 41 per group) were analyzed regarding design, metallurgy, and mechanical performance, while shaping ability (untouched canal walls, volume of removed dentin and hard tissue debris) was tested in 36 anatomically matched root canals of mandibular molars. The results were compared using one-way ANOVA, post hoc Tukey, and Kruskal–Wallis tests, with a significance level set at 5%. All instruments showed symmetrical cross-sections, with asymmetrical blades, no radial lands, no major defects, and almost equiatomic nickel–titanium ratios. Differences were noted in the number of blades, helical angles, cross-sectional design, and tip geometry. The Genius Proflex and the TruNatomy instruments had the highest and lowest R-phase start and finish temperatures, as well as the highest and lowest time and cycles to fracture (p 0.05). No differences among tested systems were observed regarding the maximum torque, angle of rotation prior to fracture, and shaping ability (p > 0.05). The instruments showed similarities and differences in their design, metallurgy, and mechanical properties. However, their shaping ability was similar, without any clinically significant errors. Understanding these characteristics may help clinicians to make decisions regarding which instrument to choose for a particular clinical situation.publishersversionpublishe

A caminho de um ambiente adaptativo de aprendizagem baseado no nível de aquisição de conhecimentos do estudante

A grande maioria dos Sistemas de Gerenciamento de Aprendizagem predominantemente em uso no ensino com suporte computacional são estáticos e lineares, ou seja, apresentam o mesmo conteúdo instrucional para os diversos estudantes sem considerar o nível de aquisição de conhecimentos de cada um. Isso torna esses ambientes muitas vezes desestimulantes para estudantes que estão num nível mais avançado e inibidores para aqueles que estão num nível ainda inicial. Este artigo tem por objetivo apresentar o modelo de funcionamento de um ambiente computacional de aprendizagem baseado no nível de aquisição de conhecimentos do estudante. Ao disponibilizar para cada estudante uma sugestão de seqüência instrucional adequada ao seu perfil atual e atualizada dinamicamente, o ambiente criará condições para que os mesmos possam guiar o próprio aprendizado de forma personalizada.Most of Learning Management Systems predominantly in use at computational support education are static and linear. They present the same instructional content for several students without considering their own knowledge acquisition level, becoming these environments sometimes unstimulating for students who are in a higher level and in other hand inhibited for students who are still in an initial level. This article aims to present the model of a computational learning environment based on the students’ knowledge acquisition level. Providing to each student a suggestion of an instructional sequence suitable to their current profile, and dynamically updated, the environment will create conditions for students guide their own learning in a personalized way.VI Workshop de Tecnología Informática Aplicada en EducaciónRed de Universidades con Carreras en Informática (RedUNCI

A caminho de um ambiente adaptativo de aprendizagem baseado no nível de aquisição de conhecimentos do estudante

A grande maioria dos Sistemas de Gerenciamento de Aprendizagem predominantemente em uso no ensino com suporte computacional são estáticos e lineares, ou seja, apresentam o mesmo conteúdo instrucional para os diversos estudantes sem considerar o nível de aquisição de conhecimentos de cada um. Isso torna esses ambientes muitas vezes desestimulantes para estudantes que estão num nível mais avançado e inibidores para aqueles que estão num nível ainda inicial. Este artigo tem por objetivo apresentar o modelo de funcionamento de um ambiente computacional de aprendizagem baseado no nível de aquisição de conhecimentos do estudante. Ao disponibilizar para cada estudante uma sugestão de seqüência instrucional adequada ao seu perfil atual e atualizada dinamicamente, o ambiente criará condições para que os mesmos possam guiar o próprio aprendizado de forma personalizada.Most of Learning Management Systems predominantly in use at computational support education are static and linear. They present the same instructional content for several students without considering their own knowledge acquisition level, becoming these environments sometimes unstimulating for students who are in a higher level and in other hand inhibited for students who are still in an initial level. This article aims to present the model of a computational learning environment based on the students’ knowledge acquisition level. Providing to each student a suggestion of an instructional sequence suitable to their current profile, and dynamically updated, the environment will create conditions for students guide their own learning in a personalized way.VI Workshop de Tecnología Informática Aplicada en EducaciónRed de Universidades con Carreras en Informática (RedUNCI

Hydrogels Based on Chitosan and Chitosan Derivatives for Biomedical Applications

Chitosan (CS) is a polymer obtained from chitin, being this, after the cellulose, the most abundant polysaccharide. The fact of (i) CS being obtained from renewable sources; (ii) CS to possess capability for doing interactions with different moieties being such capability dependent of pH; (iii) plenty of possibilities for chemical modification of CS; and (iv) tuning the final properties of CS derivatives makes this polymer very interesting in academic and technological points of view. In this way, hydrogels based on CS and on CS derivatives have been widely used for biomedical applications. Other important technological applications can be also cited, such as adsorbent of metals and dyes in wastewater from industrial effluents. In pharmaceutical field, hydrogels based on CS are often used as drugs’ and proteins’ carrier formulations due to the inherent characteristics such as the biocompatibility, nontoxicity, hydrophilicity, etc. This chapter is an attempt for updating and joining the plenty of available information regarding the preparation, characterization, and biomedical application of hydrogels based on chitosan and chitosan derivatives. More than 260 references are provided, being the majority of them published in the last 10 years

It Takes Two to Tango, Part II : Synthesis of A-Ring Functionalised Quinones Containing Two Redox-Active Centres with Antitumour Activities

In 2021, our research group published the prominent anticancer activity achieved through the successful combination of two redox centres (ortho-quinone/para-quinone or quinone/seleniumcontaining triazole) through a copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. The combination of two naphthoquinoidal substrates towards a synergetic product was indicated, but not fully explored. Herein, we report the synthesis of 15 new quinone-based derivatives prepared from click chemistry reactions and their subsequent evaluation against nine cancer cell lines and the murine fibroblast line L929. Our strategy was based on the modification of the A-ring of paranaphthoquinones and subsequent conjugation with different ortho-quinoidal moieties. As anticipated, our study identified several compounds with IC50 values below 0.5 µM in tumour cell lines. Some of the compounds described here also exhibited an excellent selectivity index and low cytotoxicity on L929, the control cell line. The antitumour evaluation of the compounds separately and in their conjugated form proved that the activity is strongly enhanced in the derivatives containing two redox centres. Thus, our study confirms the efficiency of using A-ring functionalized para-quinones coupled with ortho-quinones to obtain a diverse range of two redox centre compounds with potential applications against cancer cell lines. Here as well, it literally takes two for an efficient tango

Natural polyprenylated benzophenones: keto-enol tautomerism and stereochemistry

The keto-enol tautomerism and stereochemistry study of a HIV-inhibitory natural benzophenone, (1R,5R,7R,8S)-(+)-3-(10-(3,4-dihydroxyphenyl)-10-hydroxymethylene)-8-methyl -1,5,7-tris(3-methyl-2-butenyl)-8-(4-methyl-3-pentenyl)-bicyclo[3.3.1]nonane-2,4,9-trione (a), isolated from Garcinia brasiliensis seeds is presented. The crystal structure of (a), which is also know as guttiferona A, was determined by X-ray diffraction and its intra and inter-molecular geometries discussed and compared with two analogue natural benzophenones: clusianone and epiclusianone. In (a), the hydroxyl H atom from enolizable 2,4,10-trione moiety is linked in the oxygen atom bonded to 10-(3,4-dihydroxyphenyl)methylene group, in opposition to the related natural benzophenones, where this analogue H-atom is placed in different O-atoms from bicyclo[3.3.1]nonane ring system. Such behaviour can be explained by the presence of aromatic OH6 group in (a) that origins a further delocalized resonance path along of 3,4-dihydroxyphenyl-C10-OH2 group. In addition, the (a) stereochemistry around C7 atom is compared with known structures of clusianone and epiclusianone and the influence from configuration in this chiral C-atom to structural features found in the enolizable system is proposed

Form III-like conformation and Form I-like packing in a chloroform channel solvate of the diuretic drug chlortalidone

Chlortalidone (CTD) is an antihypertensive drug for which only two solid state phases have been structurally elucidated thus far. Here, we have prepared a chloroform solvate thereof, namely, CTD Form IV, and its structure was compared to those of Form I and Form III. Its two conformers exhibit a dual structural feature in relation to the antecedent polymorphs. Both CTD molecules of Form IV adopt a Form III-like conformation, which is featured, if the conformation of CTD Form I is used as a reference, by a rotation of about 90 degrees on the axis of the C-C bond bridging the substituted benzene and isoindolinyl rings. However, CTD Form IV assembles as in the Form I crystal packing despite the different stacking fashion of their centrosymmetric dimers. In contrast to Form I, there is no offset stacking in Form IV, which forces a bend of ca. 24 degrees between the planes passing through the isoindolinyl moieties of two [100]-stacked dimers. Chloroform molecules at a maximum stoichiometry of 0.25 mol per mol of the drug play a stabilizing role in the assembly of Form IV by filling the channels formed on the crystals.FAPEMIG [APQ-02685-09, APQ-01093-10]FAPEMIGFINEPFINEP [134/08]CAPESCAPES [AUXPE-PNPD 1865/2008]CNPqCNPq [472623/2011-7, 476870/2011-9

Evolução Histórica da Participação do Brasil nos Jogos Paralímpicos de Verão

O objetivo do presente estudo foi de caracterizar a trajetória evolutiva do Brasil durante a participação dos Jogos Paralímpicos de Verão entre 1976-2020 e comparar com os países mais bem ranqueados nos Jogos Paralímpicos Rio 2016, buscando relacionar com o contexto histórico-político nacional e o plano estratégico do Comitê Paralímpico Brasileiro nos diferentes ciclos Paralímpicos. Até os Jogos Paralímpicos realizados em 2020, a delegação brasileira foi representada por um total de 774 atletas, sendo 251 medalhistas (70,9% homens; 29,1% mulheres) em 17 diferentes modalidades, quatro coletivas e treze individuais. Com relação ao tipo de deficiência, 64,9% dos atletas medalhistas apresentam deficiência física, 32,3% correspondem à deficiência visual e 2,8%, deficiência intelectual. Durante o período analisado, o Brasil conquistou 373 medalhas em participações, sendo 109 de ouro (29,2%), 132 de prata (35,4%) e 132 de bronze (35,4%). A modo conclusão, é possível destacar o avanço nas políticas públicas, plano estratégico e investimentos que favoreceram que nos últimos quatro ciclos paralímpicos, o Brasil pudesse se consolidar entre as 10 maiores potências mundiais paralímpicas, conquistando o maior número de medalhas em 2016 e o terceiro lugar no crescimento acumulado (3,2%) nos Jogos Paralímpicos de Verão entre 1988-2020, sendo superado apenas por China e Ucrânia