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Bioinspired ultratough hydrogel with fast recovery, self-healing, injectability and cytocompatibility
No full textInspired by the mussel byssus adhesiveness, a highly hydrated polymeric structure is designed to combine, for the first time, a set of interesting features for load-bearing purposes. These characteristics include: i) a compressive strength and stiffness in the MPa range, ii) toughness and the ability to recover it upon successive cyclic loading, iii) the ability to quickly self-heal upon rupture, iv) the possibility of administration through minimally invasive techniques, such as by injection, v) the swelling ratio being adjusted to space-filling applications, and vi) cytocompatibility. Owing to these characteristics and the mild conditions employed, the encapsulation of very unstable and sensitive cargoes is possible, highlighting their potential to researchers in the biomedical field for the repair of load-bearing soft tissues, or to be used as an encapsulation platform for a variety of biological applications such as disease models for drug screening and therapies in a more realistic mechanical environment. Moreover, given the simplicity of this methodology and the enhanced mechanical performance, this strategy can be expanded to applications in other fields, such as agriculture and electronics. As such, it is anticipated that the proposed strategy will constitute a new, versatile, and cost-effective tool to produce engineered polymeric structures for both science and technology
Alkali-free bioactive diopside-tricalcium phosphate glass-ceramics for scaffold fabrication: sintering and crystallization behaviours
No full textThe sintering and crystallization behaviours of alkali free bioactive glass compositions designed in the diopside
(CaO·MgO·2SiO2) tri calciumphosphate (3CaO·P2O5) binary join by varying the Di/TCP ratios were investigat
ed by hot stage microscopy and differential thermal analysis, respectively. The effects of non isothermal heating
for 1 h at 900, 1000 and 1200 °C on the structural changeswere assessed by solid state magic angle spinning nu
clear magnetic resonance (MAS NMR) and crystalline phase assemblage. The influence of the heat treatment
temperature on 3 point bending strength was also investigated. Diopside and hydroxyapatite formed as primary
crystalline phases, accompanied by calcium silicate as secondary phase, in samples are sintered at 900 °C and
1000 °C. With further increase of the heat treatment temperature to 1200 °C, whitlockite that was stated
appearing in some compositions at 1000 °C, appeared as main crystalline phase after diopside as a result of hy
droxyapatite transformation. The data gatheredwas highly relevant towards setting the experimental conditions
required for preparingwell sintered and mechanically strong glass/glass ceramic scaffolds for bone regeneration
and tissue engineering applications
Supercritical fluid extraction of sterols from Eichhornia crassipes biomass using pure and modified carbon dioxide: enhancement of stigmasterol yield and extract concentration
No full textThe supercritical extraction of stalks and leaves of Eichhornia crassipes was carried out using pure andmodified carbon dioxide. Preliminary results evidenced that the influence of temperature is weakerthan pressure and ethanol content, and thus a design of experiments was performed in the rangesof 200–300 bar and 0.0–5.0 wt.% ethanol. The optima conditions for total extraction yield ( Total) were250–300 bar and 5.0 wt.% of cosolvent, while for sterols yield ( TotalSterol) they were 300 bar and 2.5 wt.%.The latter conditions were also the most favorable to maximize the concentration of total sterols in theextracts (CTotalSterol), particularly stigmasterol (CStigm), the most abundant one. For the referred optima, Total= 1.25 wt.%, TotalSterol= 0.35 wt.%, CTotalSterol= 38.26 wt.%, and CStigm= 26.35 wt . % . This study showedalso that the individual trends of stigmasterol and cholesterol were closer to the total sterols fractionbehavior than -sitosterol did, and also that the sterols concentration were higher in the first 2 h ofextraction. In the whole, this article provides a pertinent contribution for the valorization of E. crassipesbiomass through the production of natural extracts with high contents of sterols, especially stigmasterol,mainly if one takes into account it is classified as the most problematic invasive plant worldwide
A escrita e o erro em crianças cabo-verdianas do 1º ciclo do ensino básico: Portugal/Cabo Verde
No full textMestrado em Didáctica de LínguasA realidade social em que estamos inseridos, caracteriza-se por referências cada
resumo vez mais plurais que trazem novas dificuldades na construção da identidade.
Nesta linha de pensamento parece legítimo falar de escolas multiculturais em
que a Educação Intercultural pode constituir um modelo organizador. Trata-se
de uma Educação capaz de integrar a diversidade de referências que fazem parte
da cultura das populações que acedem a escola, de promover a formação de um
conjunto de (novas) competências necessárias a afirmação pessoal e social de
cada indivíduo. É um modelo educativo que pode trazer beneficias para todas as
crianças, mais específicamente com crianças provenientes de grupos
socioculturais desfavorecidos.
Neste sentido, é importante analisar se a pertença a grupos desfavorecidos faz
aumentar a dificuldade de adaptação ao sistema escolar. Que consequências
advêm de tal facto no processo de ensinolaprendizagern, no caso específico
deste estudo, na aquisição da linguagem escrita.
O presente estudo surge numa perspectiva de reconhecer o carácter específico da
realidade sócio-linguística que envolve, de uma forma geral, os alunos cabo-
-verdianos que li-equentarn escolas portuguesas, pois a relação entre a cultura
portuguesa e cabo-verdiana integra um conjunto de elementos de afinidade, por
um lado, e de contraste, por outro.
Surge também, pela preocupação emergente da correcção de textos ao longo da
minha prática docente com alunos cabo-verdianos.
Tudo leva a crer que para estes alunos existem limitações a nível de contexto
escolar relacionadas com os programas institucionalizados ou com princípios
pedagógicos a eles subjacentes. Isto significa que existe a necessidade de se
encontrarem estratégias pedagógicas específicas para cada contexto educativo,
no caso, para o 1" Ciclo do Ensino Básico.
Pensámos, desta forma, que a aprendizagem do Português em Cabo Verde,
requer em primeiro lugar, o levantamento das necessidades de aprendizagem dos
alunos no 1" Ciclo do Ensino Básico, com vista à delineação de estratégias de
ensinolaprendizagern que permitam promover oportunidades para a construção
das competências linguístico-comunicativas.
Foi nesta perspectiva que escolhemos o tema " A Escrita e o Erro em alunos
Cabo-Verdianos do 1" Ciclo do Ensino Básico - PortugaVCabo Verde, com
vista a identificar e analisar algumas dificuldades básicas que estes alunos
enfrentam no seu processo de aprendizagem do Português.
A postura que neste trabalho se assume face aos modelos de educação para a
diversidade não é a de um multiculturalismo passivo, ou seja, de uma atitude que
apenas reconhece a diferença, mas que não é acompanhada de processos que
permitam o seu real conhecimento e a interacção entre os diversos grupos. A
postura que se assume é, sim, a de promover um conhecimento de cada cultura e
de operacionalizar estratégias de interacção que gerem mudanças individuais e
colectivas. Desejamos que as crianças de grupos sociais e culturais diversos sejam
educadas para um bilinguismo cultural onde, simultaneamente com o
conhecimento aprofundado da sua cultura de origem, desenvolvam atitudes de
alteridade e de respeito pelo outro através do conhecimento de outras culturas.The social reality in which we are involved characterizes itself by references
each more plural that bring us new difficulties on the construction of an
identity.
This reality, which is linked to the complexity of the social structure and to the
continuous social change, is expressed on the formation of an environment
abstract characterized by references even more plural that bring new difficulties on the
construction of a identity.
In this way, it seems legal to talk about multicultural schools in which
Intercultural Education can constitute an organizing model. It's about the
capability of the Education integrate a diversity of references that take care of
the culture of a population who has access to school, in promoting a training of
a set of (new) competence necessary to personal and social personality of each
individual. It's an educational model that can bring benefits for a11 children,
especially for children corning fiom ill-favoured social-cultural groups.
In this way, it's important analyse if belonging to these ill-favoured groups
makes increase the difficulty in adapting the educational system. Specifically
in this case study, which are the consequences that result fiom this teachllearn
process in the acquisition of the written language?
The present study emerges fiom a perspective in recognizing the specific
character of the social-linguistic reality that involves, generally, the capeverdean
students that attend portuguese schools once the relation between
portuguese and cape-verdean's cultures integrates a set of affinity and contrast
elements.
It appears also by the emergent aim in correcting texts in the course of my
teaching practice with cape-verdean students.
It seems to believe that for these students there are limitations as far as
educational leve1 is concerned and that are related with institutionalized
syllabuses or educational principies underlying them. This means that there is
a need of meeting specific educational strategies for each educate context, in
this particular case, the primary school.
In addition, we think that Portuguese learn's system in Cape Verde Islands
requires information about learn's system needs Çom primary schoolrs
students in view of draw teachllearn's strategies that permit promoting
opportunities to a construction of linguistic-communicate's competence.
In this perspective, we chose the subject " A Escrita e o Erro em alunos Cabo-
-Verdianos do 1." Ciclo do Ensino Básico - Portugal/ Cabo Verde" with the
goal of identifying and analysing some of the basic difficulties that these
students face in their Portuguese learn's process.
The attitude that this work assumes towards the educational models for the
diversity it's not one of a passive multiculturalism, I mean, an attitude that
merely recognizes the difference that has anything to do with processes that
permit its real knowledge and the interaction between various groups.
In this work the attitude assumed is to promote a lmowledge of each culture
and operate strategies of interaction that lead to individual and collective
changes.
We wish that children from all over social and cultural groups are educated to
face a bilingual culture where, simultaneously with a deep knowledge of their
own culture, can develop attitudes of respect towards other and different
individual by the knowledge of other cultures
Regularidade Lipschitziana dos minimizantes no cálculo das variações e controlo óptimo
Get PDFMestrado em Optimização e Teoria do ControloApresentamos um estudo unificado da regularidade lipschitziana dos minimizantes,
para o problema básico do Cálculo das Variações (CV) e suas generalizações.
Numa primeira parte, de sintese, introduzimos o problema; damos a
sua condição necessária clássica de minimalidade - a equação de Euler-Lagrange;
formulamos o teorema da existência de Tonelli; e demonstramos vários resultados
de regularidade (incluindo a descrição do fenómeno de Lavrentiev). Na
segunda parte, usamos a abordagem do Controlo Óptimo, para obter um novo
resultado de regularidade lipschitziana para os minimizantes do problema básico
do CV. A mesma estratégia é depois estendida a problemas com derivadas de
ordem superior.In this dissertation problems of the Calculus of Variations (CV) are studied,
and in particular the questions of lipschitzian regularity of minimizers are
addressed. The work consists of two main parts. Part I is a survey: we start
with the basic problem of the CV, then we introduce Euler-Lagrange necessary
minimality condition and formulate classical existence and regularity results for
minimizers, including the Lavrentiev phenomenon. In Part I1 we utilize an ap
proach of Optimal Control theory, to obtain a new result regarding lipschitzian
regularity of minimizers for the basic problem of the Calculus of Variations, and
for the problems with higher order integrands
Challenges in the identification and characterization of free amino acids and proteinaceous compounds in atmospheric aerosols: a critical review
No full textIn the last decades, there has been an increasing interest in the presence of amino acids in atmospheric aerosols, either free or in combination (e.g., proteinaceous compounds). The fact that these compounds play an important role in the chemistry and physics of air particles and atmosphere, in atmosphere/biosphere nutrient cycling, and have a direct impact in human health has encouraged further studies. The diversity in origin, type, and ambient concentrations of these amino compounds considerably complicates, thus indicating their environmental impact. Studies for the determination of amino acids in the atmosphere are extremely diverse, encompassing an array of different analytical methodologies; however, it is not possible to conduct a comparative study of these methods. In this critical review, we evaluate and compare the procedures involved in the analytical methods and studies developed thus far for the identification and quantification of amino acids in different ambient particle sizes and in different atmospheric environments (i.e., background/pristine, rural, and urban environments)
Alkali Niobate and Tantalate Perovskites as alternative photocatalysts
No full textAlkali tantalates and niobates are listed as important photocatalysts
for the development of renewable energy technologies
and environmental remediation. Herein, the photocatalytic
degradation of methylene blue dye in aqueous solution by
using highly crystalline particles with perovskite-like structures,
LiTaO3, LiNbO3, NaTaO3, NaNbO3, KNbO3, and KTaO3, is investigated.
It is demonstrated that ferroelectric KNbO3 is the most
efficient photocatalyst of those tested because it combines an
electronic band structure that can respond successfully to UVA
light with a relatively high surface energy that enhances the
catalytic properties. Additionally, the built-in electric field due
to internal polarization of ferroelectric particles may contribute
to the unique properties of this functional photocatalyst. This
work provides an ideal platform for the rational design of
more efficient ferroelectric-based photocatalytic devices
Chlorodesmus hispidus, a morphological expression of Synura spinosa (Synurophyceae)
No full textColonies identical to Chlorodesmos hispidus were found in several places in Portugal and examined in the light and scanning electron microscopes. The ultrastructure of the scales, previously unknown, was found to be identical to the scales of Synura spinosa. Consideration of the information available leads us to consider Chlorodesmos as a synonym of Synura
Load balancing optimization of telecommunication networks with two differentiated services
No full textThe Differentiated Services architecture is a scalable solution to provide differentiated Quality of Service. In this paper, we address the network load balancing optimization of such networks based on bandwidth differentiation between two services. We define the optimization problem as an Integer Programming model and propose a heuristic algorithm based on GRASP with Path Relinking. We present computational results showing that (i) good quality solutions can be computed and (ii) proper load balancing can efficiently obtain service differentiation
Deliverable D2.1: energy consumption model for amplifiers with high capacitive input sources
No full textRelatório do projeto EECCO. Inclui: Deliverable D2.1 Energy Consumption Model for Amplifiers with High Capacitive Input Sources Deliverable; D2.2 Power Control System Level Considerations