oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 1 )

2018 ( 32 )

2017 ( 23 )

2016 ( 31 )

Custom range...

Search Results: 1 - 10 of 11092 matches for " Fernanda Roberta;Lobo "
All listed articles are free for downloading (OA Articles)
Page 1 /11092
Display every page Item
Adhesion Studies of Diamond-Like Carbon Films Deposited on Ti6Al4V Alloy after Carbonitriding  [PDF]
Deiler Antonio Lima-Oliveira, Romina Paula Castro Costa, Gislene Valdete Martins, Evaldo José Corat, Vladimir Jesus Trava-Airoldi, Anderson Oliveira Lobo, Fernanda Roberta Marciano
Open Journal of Metal (OJMetal) , 2012, DOI: 10.4236/ojmetal.2012.21001
Abstract: Diamond-like Carbon (DLC) coatings have attracted significant attention due to their low friction coefficient, high degree of hardness, chemical inertness, and high wear resistance as well as and their many possible uses in metallurgical, aeronautical, and biomedical applications. However, DLC has low adhesion strength to metallic substrates. Carbonitriding was performed before DLC deposition to improve this adherence. Different concentration of nitrogen in the gas mixture was used during the carbonitriding of Ti6Al4V alloy. DLC films were subsequently grown from methane using plasma enhanced chemical vapor deposition. The samples were characterized with Raman scattering spectroscopy, nanoindentation, and tribological tests. Films from 80.0% N2 had the best friction coefficient (0.07) and a critical load of ~22 N. In the scratching test, these films had adhesive failure and they completely detached from the substrate only in the end of the tests. SEM images show carbonitring promoted a significant increase in the surface defects (homogeneously distributed) but without the presence of microcracks. EDX analysis indicated that nitrogen element was diffused throughout the thickness of the samples. Hydrogen and carbon atoms from carbonitriding formed a diffusion-barrier layer that can be used as the first step for DLC deposition. This carbonitriding can also provide a carbide layer, which serves as the precursor for the nucleation and growth of DLC films.
Proposed model for biomineralization of novel nanohydroxyapatite/vertically aligned multiwalled carbon nanotube scaffolds
Brazil, Tayra Rodrigues;Neves, Marcele Florêncio das;Regiani, Inacio;Marciano, Fernanda Roberta;Lobo, Anderson Oliveira;
Materials Research , 2013, DOI: 10.1590/S1516-14392013005000039
Abstract: for the first time, the growth mechanism of biominerals formed on plate-like nanohydroxyapatite (nhap) electrodeposited on superhydrophilic vertically aligned multi-walled carbon nanotubes (vamwcnt-o2) is presented and a model for the specific growth preference is discussed. vamwcnt-o2 films were obtained by microwave-assisted chemical vapor deposition method and funcionalized by oxygen plasma. nhap/vamwcnt-o2 nanocomposites were fabricated with a direct electrodeposition of the thin nhap films onto the vamwcnt-o2 films. the biomineralized "scaffolds" were obtained by soaking nhap/vamwcnt-o2 in simulated body fluid for 7, 14 and 21 days. results show that the carboxyl functional groups directly attached onto vamwcnt tips after oxygen plasma treatment were essential for the acceleration of the oh- formation and the deposition of plate-like nhap crystals.
In vitro biomineralization of a novel hydroxyapatite/superhydrophilic multiwalled carbon nanotube nanocomposite using simulated body fluids
Neves, Marcele Florencio;Brazil, Tayra Rodrigues;Soares, Eduardo Silva;Corat, Evaldo Jose;Marciano, Fernanda Roberta;Lobo, Anderson Oliveira;
Materials Research , 2013, DOI: 10.1590/S1516-14392013005000038
Abstract: nanobiomaterials based on superhydrophilic vertically-aligned multi-walled carbon nanotubes (vamwcnt-o2) are promising for their properties and bone tissue biocompatibility. vamwcnt-o2 films with nanohydroxyapatite (nhap) aim to improve mechanical properties and biocompatibility of this new nanocomposite due to its resemblance to bone matrix structure. this study aimed to produce in vitro biomineralized nhap/vamwcnt-o2 nanocomposites using simulated body fluid (sbf) with two different phs (6.10 and 7.40) during 7 days to obtain a new surface design with higher crystalinity and better morphology of nhap/vamwcant-o2 nanocomposites. the objective is to obtain biomineralized nanobiomaterials to enable its applicability as "scaffold" to cellular support and consequent bone tissue formation, accelerating the osseointegration. layer densification has been achieved due to polycrystalline nanoapatites deposition on surface and between the biomineralized nhap/vamwcnt-o2 nanocomposites, without any heat treatment. therefore, through its characteristics and properties these nanocomposite applications can be considered extremely viable for acceleration of in vivo regenerative processes.
Calcification in vitro of biomineralizated nanohydroxyapatite/superydrophilic vertically aligned multiwalled carbon nanotube scaffolds
Neves, Marcele Florencio;Silva, Gislene Rodrigues;Brazil, Tayra Rodrigues;Marciano, Fernanda Roberta;Pacheco-Soares, Cristina;Lobo, Anderson Oliveira;
Materials Research , 2013, DOI: 10.1590/S1516-14392013005000029
Abstract: nanocomposites based on superhydrophilic vertically aligned multi-walled carbon nanotubes (vamwcnt-o2) and nanohydroxyapatite (nhap) are of great interest in bone regenerative medicine. the biomineralization using simulated body fluid (sbf) has been extensively studied to evaluate the bioactivity of biomaterials. thus, the combination of nhap and vamwcnt-o2 is attractive and promising. the aim of this study was to evaluate the in vitro calcification of nhap/vamwcnt-o2 nanocomposites before and after the period of biomineralization in sbf. in vitro calcification of the extracellular matrix (ecm) of hob cells in culture after 24 hours was investigated through the assay of alkaline phosphatase. these promising in vitro results validate biomineralized nhap/vamwcnt-o2 as possible scaffolds for bone tissue regeneration.
Tecnologia e desafios da educa??o brasileira contemporanea
Silva, Roberta Maria Lobo da;
Trabalho, Educa??o e Saúde , 2008, DOI: 10.1590/S1981-77462008000100003
Abstract: this article presents a conceptual discussion on technology, as it relates to an educational project centered on liberty. it is a partial result of the line of research on education, culture and technology/critical theory and education research group, at the federal rural university of rio de janeiro/national council for scientific and technological development (ufrrj/cnpq). the objective of this research group is to develop research projects on the relationship between education, culture and technology, with a view to discussing the changes in the epistemological status of education in the 20th and 21st centuries. the theoretical reference centers on the work of herbert marcuse, particularly his concepts of critical rationality and technological rationality. in the light of these concepts, we will present the challenges of brazilian contemporary education, faced with a reality of immense territories that are spatially and socially segregated, and of the appeal of a society of spectacle that desensitizes the person and intensifies the commercial object as fetish. in this context we will present the possibilities of education to prepare young people for an active participation in the world of culture through the exploration of historical and aesthetic imagination, with a reference in audiovisual production.
Ruptura de paradigmas bibliotec nomicos, autoforma o e mercado de trabalho: estudo de caso
Fábio José Lobo da Fonseca,Fernanda Maria Lobo Fonseca,Nádia Lobo da Fonseca
Revista ACB , 2005,
Abstract: [Portuguese] Relaciona a atua o e inser o do bibliotecário brasileiro no mercado de trabalho aos paradigmas bibliotecon micos ainda vigentes: foco no acervo, informa o vista apenas como bem social e predominancia do ambiente de trabalho biblioteca. Discute alguns paradoxos profissionais relacionando-os aos paradigmas e às competências e habilidades requeridas nas organiza es. Demonstra que o rompimento de tais paradigmas contribuirá para ampliar a vis o e as oportunidades de trabalho, da mesma forma que os princípios do empreendedorismo e da inova o, quando aplicados à autoforma o, prática esta sugerida para fazer face aos desafios profissionais, na atualidade. Conclui apresentando estudos de casos representativos das teses defendidas. [English] It relates the Brazilian librarian’s performance and insertion in the market in the effective librarian’s paradigms: focus in the collection, information only as corporate property only and predominance of the work environment in the library. It discusses some professional paradoxes relating them with the paradigms and the competencies and abilities required in the organizations. It demonstrates that the disruption of such paradigms will contribute to extend the vision and the chances of work, in the same way that the principles of the enterprising and the innovation, when applied to self-education, this way is suggested to face the professional challenges, in the present. It concludes presenting representative studies of cases of the defended theories.
Ruptura de paradigmas bibliotec nomicos, autoforma o e mercado de trabalho: estudo de caso

Rupture of librarianship’s paradigms, self-education and work market: study of cases p. 207-223
Fábio José Lobo da Fonseca,Fernanda Maria Lobo Fonseca,Nádia Lobo da Fonseca
Revista ACB , 2006,

Abstract: Relaciona a atua o e inser o do bibliotecário brasileiro no mercado de trabalho aos paradigmas bibliotecon micos ainda vigentes: foco no acervo, informa o vista apenas como bem social e predominancia do ambiente de trabalho biblioteca. Discute alguns paradoxos profissionais relacionando-os aos paradigmas e às competências e habilidades requeridas nas organiza es. Demonstra que o rompimento de tais paradigmas contribuirá para ampliar a vis o e as oportunidades de trabalho, da mesma forma que os princípios do empreendedorismo e da inova o, quando aplicados à autoforma o, prática esta sugerida para fazer face aos desafios profissionais, na atualidade. Conclui apresentando estudos de casos representativos das teses defendidas. Abstract: It relates the Brazilian librarian’s performance and insertion in the market in the effective librarian’s paradigms: focus in the collection, information only as corporate property only and predominance of the work environment in the library. It discusses some professional paradoxes relating them with the paradigms and the competencies and abilities required in the organizations. It demonstrates that the disruption of such paradigms will contribute to extend the vision and the chances of work, in the same way that the principles of the enterprising and the innovation, when applied to self-education, this way is suggested to face the professional challenges, in the present. It concludes presenting representative studies of cases of the defended theories.
A Convenient and Safe O-Methylation of Flavonoids with Dimethyl Carbonate (DMC)
Roberta Bernini,Fernanda Crisante,Maria Cristina Ginnasi
Molecules , 2011, DOI: 10.3390/molecules16021418
Abstract: Dietary flavonoids exhibit beneficial health effects. Several epidemiological studies have focused on their biological activities, including antioxidant, antibacterial, antiviral, anti-inflammatory and cardiovascular properties. More recently, these compounds have shown to be promising cancer chemopreventive agents in cell culture studies. In particular, O-methylated flavonoids exhibited a superior anticancer activity than the corresponding hydroxylated derivatives being more resistant to the hepatic metabolism and showing a higher intestinal absorption. In this communication we describe a convenient and efficient procedure in order to prepare a large panel of mono- and dimethylated flavonoids by using dimethyl carbonate (DMC), an ecofriendly and non toxic chemical, which plays the role of both solvent and reagent. In order to promote the methylation reaction under mild and practical conditions, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) was added in the solution; methylated flavonoids were isolated in high yields and with a high degree of purity. This methylation protocol avoids the use of hazardous and high toxic reagents (diazomethane, dimethyl sulfate, methyl iodide).
Identifica??o dos elementos do trabalho padronizado na constru??o civil
Fazinga, Wanessa Roberta;Saffaro, Fernanda Aranha;
Ambiente Construído , 2012, DOI: 10.1590/S1678-86212012000300003
Abstract: standardization is a management tool aimed at reducing variability in the production process. in the context of the toyota production system (tps), standardized work (sw) is the way standardization is put into practice. this research study aims to propose specifications to create a standard for production processes in construction through an adaptation of the sw concept. a case study was carried out in a construction site, located in londrina/pr, during the execution of the reinforced concrete structure. the elements of the sw could be detected in the construction context, however some adjustments were necessary, resulting in specifications that contain the three components of the standard proposed in the literature: goal, constraints and method. the definition of goals has proved to be valid for guiding the establishment of the method. the specifications related to the method were more comprehensive than those reported in tps literature, including specifications concerned with the kit of resources for each work package and the way the kits should be moved and stored. by contrast, the standard operation routine was less detailed. it focused only on teamwork and not on individual routine throughout the day. despite the peculiarities of the construction context, sw has proved to be a potentially effective tool for reducing variability in the production process.
Revisiting the proof theory of Classical S4
Bruno Lopes,Cecília Englander,Fernanda Lobo,Marcela Cruz
Computer Science , 2012,
Abstract: In 1965 Dag Prawitz presented an extension of Gentzen-type systems of Natural Deduction to modal concepts of S4. Maria da Paz Medeiros showed in 2006 that the proof of normalisation for classical S4 does not hold and proposed a new proof of normalisation for a logically equivalent system, the system NS4. However two problems in the proof of the critical lemma used by Medeiros in her proof were pointed out by Yuuki Andou in 2009. This paper presents a proof of the critical lemma, resulting in a proof of normalisation for NS4.
Page 1 /11092
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.