563 research outputs found
Friendship and gender in preschoolers’ conflicts
Investigated the role of friendship and gender on conflict episodes of 48 preschoolers aged approximately 5 years and 8 months. Children were organized in dyads of same-sex friends and non-friends. Conflict situations were coded according to incidence, type, termination strategies, and finalizations. Gender differences were detected for type of conflict, with girls using more reasons for oppositions than boys. Termination strategies were used with a joint effect of friendship and gender: girl-friends preferred the tactic of standing firm whereas boy-friends chose more negotiation as means to deal with a disagreement, compared to the non-friend dyads. As for the results on conflict finalizations, friendship relations accounted for a significant difference found for agreement, while gender showed to be related to the use of disengagement among girls. Combined analysis between termination strategies and conflict finalizations indicated two significant differences: the first was related to friendship, through which children used more negotiation leading to agreement; the second showed a joint effect of friendship and gender, where non-friend girls tended to negotiate to reach disengagement, more often that non-friend boys. Findings for termination strategies – with girl-friends being more incisive and firm with their partners – diverge from the results provided by empirical literature, where boys are described as more autonomy- and domain oriented, and girls are prone to intimacy and social well-being in their relationships. Results are discussed with basis on previous studies conducted on conflict among preschoolers with considerations about the effects of gender and type of relationship
Sugarcane bagasse as aggregate in composites for building blocks
"Published: 29 December 2022"Each year, hundreds of millions of tons of processed sugarcane generate, by weight, 25 to
30% of bagasse as waste, whose destination is combustion for energy cogeneration. This research
proposes an alternative and more sustainable use for this waste. The use of sugarcane bagasse (SCB)
as the single aggregate in composites for building blocks was studied. The raw bagasse was used
without any treatment. As the binder, aerial lime and/or soil were used. Both provided enough
mechanical strength for non-load-bearing walls. The composite of SCB with soil achieved the best
performance in terms of mechanical resistance: 2.6 MPa in compressive strength and 2.1 MPa in
bending strength, while the composite of SCB with lime achieved 1.76 MPa and 1.7 MPa, respectively.
The higher number of fibers in the SCB/lime mixture provides better thermal insulation than clay
brick or conventional concrete, such as “hempcrete”. The lime composites obtained greater water
resistance and less loss of mechanical strength when saturated. However, the higher water absorption
coefficient makes it necessary to apply a waterproof mortar on surfaces exposed to the weather. The
replacement of supplied blocks by SCB blocks can offer a better and more economical solution that
improves the quality of the built environment and is more ecofriendly.The authors would also like to acknowledge FCT/MCTES—Foundation for Science and Technology/Ministry of Science, Technology and Higher Education, within the scope of CTAC—Center
for Territory, Environment and Construction—UIDB/0407/2020 e UIDP/04047/202
Selection bias: neighbourhood controls and controls selected from those presenting to a Health Unit in a case control study of efficacy of BCG revaccination.
BACKGROUND: In most case control studies the hardest decision is the choice of the control group, as in the ideal control group the proportion exposed is the same as in the population that produced the cases. METHODS: A comparison of two control groups in a case control study of the efficacy of BCG revaccination. One group was selected from subjects presenting to the heath unit the case attended for routine prevention and care; the second group was selected from the neighbourhood of cases. All Health Units from which controls were selected offered BCG revaccination. Efficacy estimated in a randomized control trial of BCG revaccination was used to establish that the neighbourhood control group was the one that gave unbiased results. RESULTS: The proportion of controls with scars indicating BCG revaccination was higher among the control group selected from Health Unit attenders than among neighbourhood controls. This excess was not removed after control for social variables and history of exposure to tuberculosis, and appears to have resulted from the fact that people attending the Health Unit were more likely to have been revaccinated than neighbourhood controls, although we can not exclude an effect of other unmeasured variables. CONCLUSION: In this study, controls selected from people presenting to a Health Unit overrepresented exposure to BCG revaccination. Had the results from the HU attenders control group been accepted this would have resulted in overestimation of vaccine efficacy. When the exposure of interest is offered in a health facility, selection of controls from attenders at the facility may result in over representation of exposure in controls and selection bias
Enseñanza de química a alumnos con discapacidad visual
La educación formal en Brasil tiene como primer principio la “igualdad de condiciones de acceso y permanencia en la escuela” (Brasil, 1996). En este contexto, el proyecto “Enseñanza de Química a Alumnos con Discapacidad Visual” busca desarrollar recursos y metodologías para una enseñanza de Química que atienda alumnos con ceguera o baja visión. En este proyecto, con el objetivo de atender alumnos y profesores de la enseñanza secundaria, iniciamos la adaptación del libro “Química e Sociedade” (Santos, Mol y colaboradores, 2005). El trabajo consiste de varias etapas: transcripción de los textos del libro; descripción de imágenes; construcción de modelos didácticos; adaptación de actividades experimentales
Uma abordagem prática do experimento de Oersted em sala de aula
As escolas de ensino médio brasileiras enfrentam o grande desafio de despertar o interesse dos alunos na busca pelo conhecimento. Particularmente, ao se trabalhar com o ensino de Física, nota-se grande dificuldade e desinteresse por parte dos alunos. Segundo vários autores (SOUSA, 2010; MARTINS, 2014), um dos principais motivos seriam as aulas monótonas, cheias de cálculos, e sem conexões da teoria com a prática. Em função dessas dificuldades, tem-se buscado “aulas mais dinâmicas na tentativa de fazer do aluno um agente no processo de ensino-aprendizagem” (GUEDES, 2017), atribuindo ao docente a responsabilidade de disponibilizar conteúdos e/ou abordagens que despertem nos alunos o interesse pelo estudo/aprendizado e oriente-os rumo a uma nova maneira de construção do conhecimento.
Neste sentido, propõe-se neste trabalho a abordagem de um tema através da construção e análise de experimentos, uma vez que, de acordo com o relatado por outros autores (MARTINS, 2014; MORAES; JÚNIOR, 2014; QUINTAL; SANTOS; GASPAR, 2005; FILHO; CALUZI, 2009), a realização de experimentos durante as aulas permite uma maior interação entre professor e alunos, e destes últimos com os conceitos estudados, além de ser uma forma mais atraente de prender a atenção dos mesmos, contribuindo de maneira importante para o aprendizado.
Assim, decidiu-se pela construção de um experimento de baixo custo para se trabalhar conteúdos históricos e conceituais de eletromagnetismo. Foi escolhida a experiência de Oersted, que teve papel fundamental no desenvolvimento do eletromagnetismo. Indo além de uma simples demonstração, o experimento desenvolvido possibilita ao aluno verificar que o módulo do campo magnético produzido por um fio retilíneo infinito decresce com o inverso da distância
Association between Prenatal Care and Gestational Weight Gain: Cross-Sectional Study in a Low-Income Area of Rio de Janeiro
Objetivo: Verificar a associação entre a adequação da assistência pré-natal e o ganho de peso gestacional (GPG) em puérperas brasileiras de baixa renda. Métodos: Estudo transversal no município de Mesquita-RJ, incluindo 281 mulheres no pós-parto imediato. O GPG foi classificado como adequado, insuficiente e excessivo de acordo com as recomendações do Institute of Medicine (IOM). O número de consultas do pré-natal foi categorizado (1: nenhuma consulta; 2: 1-3 consultas; 3: 4-6 consultas; 4: 7 ou mais consultas) e o início do pré-natal, segundo as semanas gestacionais (SG), foi utilizado como variável contínua. A assistência pré-natal (AP) avaliou as duas dimensões agrupadas do Índice de Kotelchuck: adequado (adequado + mais adequado) ou inadequado (intermediário e inadequado). Modelos de regressão logística multinomial foram utilizados para estimar as associações entre assistência pré-natal inadequada e GPG. Resultados: AP foi iniciada em média com 12,6 (± 6,9) SG; 8,2% das mulheres (n = 23) fizeram ≤ 4 consultas de pré-natal e 38,4% (n = 108) foram classificadas com AP inadequada. Em média, o GPG foi de 12,9 kg (± 6,2) e 36,5%, 31,0% e 32,5% das mulheres apresentaram GPG adequado, insuficiente e excessivo, respectivamente. Após o ajuste, a inadequação da AP (OR = 2,01; IC 95% = 1,03-3,90) foi associada a uma maior probabilidade de GPG abaixo das recomendações do IOM. Conclusão: Observou-se uma associação significativa entre a inadequação da assistência pré-natal e o GPG insuficiente, o que reforça a relevância da adequada AP para monitorar o adequado GPG e intervir precocemente na gestação
IFN-γ Production Depends on IL-12 and IL-18 Combined Action and Mediates Host Resistance to Dengue Virus Infection in a Nitric Oxide-Dependent Manner
Dengue is a mosquito-borne disease caused by one of four serotypes of Dengue virus (DENV-1–4). Severe dengue infection in humans is characterized by thrombocytopenia, increased vascular permeability, hemorrhage and shock. However, there is little information about host response to DENV infection. Here, mechanisms accounting for IFN-γ production and effector function during dengue disease were investigated in a murine model of DENV-2 infection. IFN-γ expression was greatly increased after infection of mice and its production was preceded by increase in IL-12 and IL-18 levels. In IFN-γ−/− mice, DENV-2-associated lethality, viral loads, thrombocytopenia, hemoconcentration, and liver injury were enhanced, when compared with wild type-infected mice. IL-12p40−/− and IL-18−/− infected-mice showed decreased IFN-γ production, which was accompanied by increased disease severity, higher viral loads and enhanced lethality. Blockade of IL-18 in infected IL-12p40−/− mice resulted in complete inhibition of IFN-γ production, greater DENV-2 replication, and enhanced disease manifestation, resembling the response seen in DENV-2-infected IFN-γ−/− mice. Reduced IFN-γ production was associated with diminished Nitric Oxide-synthase 2 (NOS2) expression and NOS2−/− mice had elevated lethality, more severe disease evolution and increased viral load after DENV-2 infection. Therefore, IL-12/IL-18-induced IFN-γ production and consequent NOS2 induction are of major importance to host resistance against DENV infection
Free 2-propen-1-amine derivative and inclusion complexes with beta-cyclodextrin: scanning electron microscopy, dissolution, cytotoxicity and antimycobacterial activity
Inclusion complexes and physical mixtures of isomeric mixture of E/Z (50:50) of 3-(4'-bromo-[1,1'-biphenyl]-4-yl)-3-(4-bromophenyl)-N,N-dimethyl-2-propen-1-amine (BBAP) and beta-cyclodextrin (beta-CD) in the molar proportion of 1:1 and 1:2 were analyzed by scanning electron microscopy. The dissolution behavior of BBAP and of the inclusion complexes were also evaluated for six hours. By scanning electron microscopy (SEM), it was possible to observe an inclusion complex formed between BBAP and beta-CD by co-evaporation, either in the molar proportion of 1:1 or 1:2. In the physical mixtures, no complex was observed as previously detected by physicochemical analysis. The dissolution studies showed that the inclusion complexes BBAP/beta-CD 1:1 and 1:2 released respectively 49.07 ± 1.48 and 40.26 ± 3.90% of BBAP during six hours. Free BBAP was less soluble than the inclusion complex and reached 9.00 ± 0.75% of dissolution. Biological assays, such as cytotoxicity to J774 macrophages and to a permanent lung fibroblast cell line (V79), indicated that the BBAP does not exhibit any additional toxic effect with the beta-CD complexes. However, the complexes were less cytotoxic to V79 cells than the free form. The BBAP/beta-CD inclusion complexes were more effective (MIC) than the free compound on several mycobacteria strains. Similar behavior was observed for BBAP/beta-CD complexes and rifampicin, a front-line antitubercular drug, on M. tuberculosis H37Rv growing inside J774 macrophages.Complexos de inclusões e misturas físicas contendo mistura isomérica E/Z (50:50) de 3-(4'-bromo-[1,1'-bifenil]-4-il)-3-(4-bromofenil)-N,N-dimetil-2-propen-1-amina (BBAP) e beta-ciclodextrina (b-CD) nas proporções molares de 1:1 e 1:2 foram analisados por microscopia eletrônica de varredura (SEM). O perfil de dissolução do BBAP e dos complexos de inclusões foram também avaliados durante 6 horas. Por microscopia eletrônica de varredura foi possível observar os complexos de inclusões formados entre BBAP e beta-CD por co-evaporação nas proporções molares de 1:1 e 1:2. Como previamente detectado pela caracterização físico-química, na mistura física não se observou a presença de complexo de inclusão. Os estudos de dissolução mostraram que os complexos de inclusões 1:1 e 1:2 liberaram, respectivamente 49.07 ± 1.48 e 40.26 ± 3.90% de BBAP durante 6 horas. BBAP na forma livre foi menos solúvel que os complexos de inclusões e atingiu 9.00 ± 0.75% de dissolução. Os ensaios de citotoxicidade em macrófagos J774 e em uma linhagem de células fibroblásticas de pulmão (V79) indicaram que o BBAP não exibiu efeito tóxico adicional quando complexado com beta-CD. Entretanto, os complexos de inclusões foram menos tóxicos para células V79 que BBAP na forma livre. Os complexos de inclusões BBAP/beta-CD foram mais efetivos (CIM) que o composto livre em várias cepas de micobactérias. Resultados semelhantes foram observados sobre M. tuberculosis H37Rv intracelular para os complexos de inclusões BBAP/b-CD e rifampicina, uma droga anti-tuberculose de primeira linha.682689Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq
The influence of polysaccharide coating on the physicochemical parameters and cytotoxicity of silica nanoparticles for hydrophilic biomolecules delivery
The present work reports the effect of polysaccharides (chitosan and sodium alginate) on silica nanoparticles (SiNP) for hydrophilic molecules delivery taking insulin as model drug. The influence of tetraethyl orthosilicate (TEOS) and homogenization speed on SiNP properties was assessed by a 22 factorial design achieving as optimal parameters: 0.43 mol/L of TEOS and homogenization speed of 5000 rpm. SiNP mean particle size (Z-Ave) was of 256.6 nm and polydispersity index (PI) of 0.218. SiNP coated with chitosan (SiNP-CH) or sodium alginate (SiNP-SA) increased insulin association efficacy; reaching 84.6% (SiNP-SA) and 90.8% (SiNP-CH). However, coated SiNP released 50%–60% of the peptide during the first 45 min at acidic environment, while uncoated SiNP only released 30%. Similar results were obtained at pH 6.8. The low Akaike’s (AIC) values indicated that drug release followed Peppas model for SiNP-SA and second order for uncoated SiNP and SiNP-CH (pH 2.0). At pH 6.8, the best fitting was Boltzmann for Ins-SiNP. However, SiNP-CH and SiNP-SA showed a first-order behavior. Cytotoxicity of nanoparticles, assessed in Caco-2 and HepG2 cells, showed that 100 to 500 µg/mL SiNP-CH and SiNP-SA slightly decreased cell viability, comparing with SiNP. In conclusion, coating SiNP with selected polysaccharides influenced the nanoparticles physicochemical properties, the insulin release, and the effect of these nanoparticles on cell viability.This research was supported by the Fundação para a Ciência e Tecnologia (FCT, Portugal), by grating PhD scholarships SFRH/BD/60640/2009 (T. Andreani), SFRH/BD/80335/2011 (J.F. Fangueiro) and SFRH/BD/111274/2015 (P.M.V. Fernandes), and funded projects UID/AGR/04033/2019 (CITAB), and M-ERANET/0004/2015-PAIRED (Partnership Agreement PT2020).info:eu-repo/semantics/publishedVersio
CD3e expression in HTLV-1-infected individuals is associated with proviral load and Tax expression
Financial support: FUNDHERP, CTC, INCTC, FAPESP, CNPq and CAPES
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