1,360 research outputs found
Removal of Paracetamol and Cu2+ from Water by Using Porous Carbons Derived from Agrowastes
Publisher Copyright:
© 2023 by the authors.Dende and babassu coconuts are largely used in tropical countries, namely in Brazil, for the extraction of oils from kernels. The remaining biowastes are industrially processed to produce porous carbons (PCs). PCs derived from dende and babassu biowastes and produced at an industrial scale have been characterized by textural, chemical, and ecotoxicological parameters. A commercial activated carbon (CC) of mineral origin has been used as a benchmarking material. Although the CC sample presented a higher surface area (SBET = 1083 m2/g), the PCs derived from the biowastes were richer in micropores (Vmicro = 0.25–0.26 cm3/g), while the CC carbon presented wider pore size distribution with a higher mesopore volume (Vmeso = 0.41 cm3/g). All the adsorbents used in this work have shown a non-acute ecotoxic behavior for the bacterium Vibrio fischeri (EC50-30 min > 99% v/v). The adsorbents have been tested for paracetamol and Cu2+ adsorption in mono- and bicomponent solutions. The uptake capacities of paracetamol (qe, 98–123 mg g−1) and Cu2+ (qe, 15–18 mg g−1) from monocomponent solutions were similar to the ones obtained in the bicomponent solutions, indicating no competition or cooperative effects but a site-specific adsorption. This finding represents an advantage for the removal of these adsorbates when present in the same solution as they can be adsorbed under similar rates as in the single systems. Paracetamol adsorption was related to micropore filling, π-π interactions, and H-bonding, whereas Cu2+ removal was attributed to the cation exchange mechanism and complexation to the hydroxyl groups at the carbons’ surface.publishersversionpublishe
Tribochemistry of phosphorus additives: Experiments and first-principles calculations
Organophosphorus compounds are common additives included in liquid lubricants for many applications, in particular automotive applications. Typically, organic phosphites function as friction-modifiers whereas phosphates as anti-wear additives. While the antiwear action of phosphates is now well understood, the mechanism by which phosphites reduce friction is still not clear. Here we study the tribochemistry of both phosphites and phosphates using gas phase lubrication (GPL) and elucidate the microscopic mechanisms that lead to the better frictional properties of phosphites. In particular, by in situ spectroscopic analysis we show that the friction reduction is connected to the presence of iron phosphide, which is formed by tribochemical reactions involving phosphites. The functionality of elemental phosphorus in reducing the friction of iron-based interfaces is elucidated by first principle calculations. In particular, we show that the work of separation and shear strength of iron dramatically decrease by increasing the phosphorus concentration at the interface. These results suggest that the functionality of phosphites as friction modifiers may be related to the amount of elemental phosphorus that they can release at the tribological interface
Morphological and conductivity studies of di-ureasil xerogels containing lithium triflate
Sol–gel derived poly(oxyethylene)/siloxane hybrids doped with lithium triflate, LiCF3SO3, have been investigated. The host hybrid matrix of these materials, named di-ureasil and represented by U(600), is composed by a siliceous framework to which polyether chains containing 8.5 oxyethylene repeat units are covalently bonded through urea linkages. Xerogel samples U(600)nLiCF3SO3 with n (where n is the molar ratio of oxyethylene moieties per Li+ ion) between ∞ and 0.1 have been examined. X-ray diffraction and differential scanning calorimetry have provided conclusive evidence that the xerogels analyzed are entirely amorphous. The salt-rich material with n=1 exhibits the highest conductivity over the whole range of temperature analyzed (e.g. 4.3×10−6 and 2.0×10−4 Ω−1 cm−1, respectively, at 25 and 94 °C).Fundação para a Ciência e a Tecnologia (FCT
Evaluando el progreso de la eficiencia con tecnologÃa en una cadena de hoteles española
This paper analyzes the changes in the total factor productivity index of a Spanish hotel chain in the
period from 2007 to 2010 with the purpose of identifying efficiency patterns for the chain in a period of
financial crisis. The data envelopment analysis (DEA) Malmquist productivity index was used to estimate
productivity change in 38 hotels of the AC chain. Results reveal AC hotels’ efficiency trends and,
therefore, their competitiveness in the recession period; they also show the changes experienced in
these hotels’ total productivity and its components: technological and efficiency changes. Positive
efficiency changes were due to positive technical efficiency rather than technological efficiency. The
recession period certainly influenced the performance of AC Hotels, which focused on organizational
changes rather than investing in technology.Este artigo analisa as mudanças no fator total de produtividade de uma cadeia de hotéis na Espanha,
no perÃodo de 2007-2010, com o propósito de identificar os padrões da cadeia em um perÃodo
de crise financeira. O Ãndice data envelopment analysis (DEA) Malmquist de produtividade foi usado
para estimar a mudança da produtividade nos 38 hotéis da AC Cadeia de Hotéis. Os resultados revelaram
as tendências de eficiência e competitividade da AC Hotéis em um perÃodo de recessão, bem
como as mudanças vivenciadas na produtividade total e, consequentemente, em seus componentes
de eficiência e tecnológicos. O perÃodo de recessão influenciou, sem dúvida, o comportamento da AC
Hotéis, que buscou mais mudanças organizacionais do que tecnológicas.Este artÃculo analiza los cambios del Ãndice de productividad del factor total de una cadena de hoteles
españoles en el periodo de 2007 hasta 2010, con el propósito de identificar patrones de eficiencia
para la cadena en un periodo de crisis financiera. El Ãndice de productividad data envelopment analysis
(DEA) Malmquist fue utilizado para estimar el cambio de productividad en 38 hoteles de la cadena
AC. Los resultados revelan las tendencias de la eficiencia de los hoteles AC y, por lo tanto, su competitividad
en el periodo de recisión; ellos también demuestran los cambios experimentados en la
productividad total de eses hoteles y sus componentes: cambios de eficiencia y tecnológicos. Cambios
de eficiencia positivos se debieron más bien a eficiencias técnicas positivas que a eficiencias tecnológicas.
El periodo de recesión ciertamente ha influenciado los Hoteles AC, que enfocaron más en los
cambios organizacionales que en invirtiendo en tecnologÃa
Recommended from our members
Retrospective analysis of risk factors and gaps in prevention strategies for mother-to-child HIV transmission in Rio de Janeiro, Brazil
Background
Despite great progress made in methods to prevent mother-to-child transmission of HIV (MTCT), delivery and uptake of these measures remains a challenge in many countries. Although the Brazilian Ministry of Health aimed to eliminate MTCT by 2015, infection still occured in 15–24% of infants born to HIV-infected mothers. We sought to identify remaining factors that constrain MTCT elimination.
Methods
We conducted a retrospective, matched case-control study by reviewing hospital charts of infants born to HIV-infected mothers between 1997 and 2014 at three MTCT reference hospitals in the Rio de Janeiro metropolitan area. Cases were defined as HIV-exposed children with two positive HIV tests before 18Â months of age; controls were defined as HIV-exposed children with two negative HIV tests before 18Â months of age. We performed bivariate and MTCT cascade analyses to identify risk factors for MTCT and gaps in prevention services.
Results
We included 435 infants and their mothers (145 cases, 290 controls). Bivariate analyses of MTCT preventative care (PMTCT) indicated that cases were less likely to complete all individual measures in the antenatal, delivery, and postnatal period (p < 0.05). Assessing completion of the PMTCT cascade, the sequential steps of PMTCT interventions, we found inadequate retention in care among both cases and controls, and cases were significantly less likely than controls to continue receiving care throughout the cascade (p < 0.05). Motives for incompletion of PMTCT measures included infrastructural issues, such as HIV test results not being returned, but were most often due to lack of care-seeking. Over the course of the study period, PMTCT completion improved, although it remained below the 95% target for antenatal care, HIV testing, and antenatal ART set by the WHO. Adding concern, evaluation of co-infections indicated that case infants were also more likely to have congenital syphilis (OR: 4.29; 95% CI: 1.66 to 11.11).
Conclusions
While PMTCT coverage has improved over the years, completion of services remains insufficient. Along with interventions to promote care-seeking behaviour, increased infrastructural support for PMTCT services is needed to meet the HIV MTCT elimination goal in Brazil as well as address rising national rates of congenital syphilis
Didática no online: novas coreografias e seus olhares
A didática no online traz uma configuração inovadora e peculiar no caminho das práticas e nas criações pedagógicas para o processo de ensino e aprendizagem. O presente painel estrutura-se na reflexão e nas experiências do professor como coreógrafo estratégico na convergência do online com o presencial, provocando oportunidades para as aprendizagens profundas e significativas. As categorias presentes na fundamentação teórica são: interação, estratégias, redes, cibercultura e assincronicidade. A proposta é parte das investigações em curso sobre as tendências da didática nos contextos online, as discussões apresentadas refletem a produção cientÃfica no campo da didática do contexto brasileiro e europeu. Os caminhos metodológicos englobam a análise qualitativa e quantitativa suportada por referenciais bibliográficos, reflexões e discussões em rede a partir de práticas colaborativas e de coaprendizagem entre as investigadoras. A didática apresentada fundamenta-se em diferentes vertentes teóricas adoptando referenciais especÃficos. É proposto a continua inferência nas discussões e realizações para a sustentabilidade da didática do assÃncrono em convergência do presencial com o online. A partir dos vários eixos teóricos analisados surgem indicadores e variáveis sustentáveis que o painel trará nas propostas que serão apresentadas, nunca finalizadas, mas como elementos de discussão já fundamentados e testados com novos olhares e coreografias que potencializam esse trabalho em sua melhor atualização e gestão nas aprendizagem do século XXI. A didática que as investigadoras envolvidas discutem está numa configuração que considera os formatos oferecidos pelas tecnologias, com sua análise e os processos de didatização desses cenários, trazendo uma intencionalidade pedagógica ainda difÃcil de ser concretizada nas propostas de ensino e aprendizagem no online.info:eu-repo/semantics/publishedVersio
Elaboração de manual sobre fibras alimentares e constipação intestinal
Objetivo: elaborar um manual com alimentos fonte de fibras para ser usado na composição da dieta lÃquida homogênea dos pacientes em pós-operatório no HRAC, de todas as idades, para reduzir ou prevenir a constipação intestinal. Métodos: o manual contém temática que esclarece sobre a importância das fibras alimentares, classificação, fontes, quantidades de uso, interação com outros nutrientes, forma de preparo, solubilidade, funções e problemas causados pelo excesso de ingestão. Consta também de uma lista de alimentos com quantidades de fibras presentes por 100gramas de cada alimento. Tais dados foram retirados da Tabela Brasileira de composição de Alimentos da UNICAMP e da Tabela Brasileira de Composição de Alimentos da USP. O manual foi elaborado pelas alunas do programa de Aprimoramento Profissional Fundap e será distribuÃdo gratuitamente para todos os pacientes em pós-operatórios submetidos à dieta lÃquida homogênea. Além disto, o manual será disponibilizado nos sites www.centrinho.usp.br/manual e www.redeprofis.com.br. para consulta e cópias gratuitas. A arte e as ilustrações do manual foram feitas por aluno do Curso de Publicidade e Propaganda da USC. Resultados: O uso das fibras será orientado de forma preventiva para os pacientes que não apresentam constipação intestinal e de forma corretiva para os já constipados. Conclusões: A constipação intestinal é um problema de saúde pública no Brasil, principalmente entre as mulheres e tem seu quadro agravado quando estes indivÃduos são submetidos a dietas lÃquidas e homogêneas, aonde os alimentos são liquidificados e coados e os resÃduos (fibras) desprezados. Sendo assim, a composição desta dieta tem que ser enriquecida com fibras alimentares para prevenir ou corrigir a constipação intestinal
Elaboration of handbook about dietary fibers and bowel constipation
Objective: to elaborate a handbook with high-fiber foods to be used in the composition of the homogeneous liquid diet for patients in postoperative period to reduce or prevent the bowel constipation. Methods: the handbook highlights the importance of dietary fibers, classification, food sources, amount of use, interaction with other nutrients, directions for preparation, solubility, functions and problems caused by the excess ingestion. It also contains a list of food with fibers quantities present in 100 grams of each food. Such data were obtained from the Tabela Brasileira de Composição de Alimentos of Unicamp and Tabela Brasileira de Composição de Alimentos of University of São Paulo. The handbook was elaborated by students from Fundap Professional Improvement Program and distributed for free for all patients of the Hospital for Rehabilitation of Craniofacial Anomalies, in postoperative period, receiving homogeneous liquid diet. The handbook was also made available in the homepages www.centrinho.usp/manual and www.redeprofis.com.br for consultation and free copies. The handbook art and illustrations were made by a student of Marketing rom USC. Results: The use of fibers will be oriented in a preventive form for patients not showing bowel constipation and in a corrective form for those already constipated. Conclusions: Bowel constipation is a public health problem in Brazil, mainly among women, and it becomes worse when individuals are submitted to a homogeneous liquid diet in which the foods are liquefied and filtered and the residues (fibers) are rejected. In such case, the composition of this diet needs to be enriched with dietary fibers to prevent or correct the bowel constipation
- …