Instrumentação para a caracterização dielétrica de filmes biodegradáveis

A caracterização dielétrica de um material pode ser usada como uma técnica não destrutiva para avaliar e monitorar sua qualidade, bem como no entendimento da relação estrutura-propriedade de um material, através de suas propriedades dielétricas em função da frequência, temperatura, composição química do material, dentre outros. Na literatura há escassez de trabalhos e dados de caracterização dielétrica de filmes a base de biopolímeros. Diante desse contexto, o objetivo deste trabalho foi o desenvolvimento e a construção de uma instrumentação alternativa a equipamentos disponíveis no mercado, como analisadores de rede e de impedância, que pudesse ser utilizada para a caracterização dielétrica de filmes biodegradáveis a base de gelatina. Foi utilizado o método de placas paralelas na determinação da parte real da permissividade conhecida como permissividade relativa ou constante dielétrica (ε\'). O circuito utilizado para a instrumentação foi um oscilador astável com funcionamento baseado no amplificador operacional (741) chaveado pela carga de um capacitor de placas paralelas cujo dielétrico foi uma amostra de filme biodegradável. A partir dos valores da frequência de oscilação e geometria do capacitor, foi possível calcular a capacitância de cada amostra e, consequentemente obter os valores da permissividade relativa do filme, usando relações básicas bem estabelecidas. Os filmes de gelatina foram produzidos pela técnica de casting sendo utilizados como plastificantes o glicerol (G), o sorbitol (S) e suas misturas, na proporção (G:S) de 30:70, 50:50 e 70:30. Os filmes foram caracterizados quanto à umidade e cristalinidade. A permissividade relativa (ε\') dos filmes, determinada a temperatura ambiente, foi avaliada em função da frequência (5 a 50 kHz), tempo de armazenamento, do teor de umidade e tipo de plastificante. A instrumentação projetada e construída foi capaz de medir com precisão a permissividade relativa das amostras, sendo que essa propriedade diminuiu com o aumento da frequência para todos os filmes. Mantendo-se a frequência constante, não houve variação de ε\' para os filmes de gelatina, independente do plastificante, ao longo de um mês de armazenamento a 24 ± 3 °C. O efeito da umidade foi observado em frequências menores que 25 kHz, sendo que quanto maior o teor de umidade maior a permissividade relativa. O efeito do tipo de plastificante na permissividade relativa dos filmes foi observado a baixas frequências (5 kHz) e filmes plastificados com sorbitol apresentaram maiores valores de ε\'. Os filmes plastificados com maior teor de umidade apresentaram menor cristalinidade, portanto maior mobilidade molecular e consequentemente maior a permissividade relativa.

The physical and chemical properties of eumelanin

In this article, we review the current state of knowledge concerning the physical and chemical properties of the eumelanin pigment. We examine properties related to its photoprotective functionality, and draw the crucial link between fundamental molecular structure and observable macroscopic behaviour. Where necessary, we also briefly review certain aspects of the pheomelanin literature to draw relevant comparison. A full understanding of melanin function, and indeed its role in retarding or promoting the disease state, can only be obtained through a full mapping of key structure-property relationships in the main pigment types. We are engaged in such an endeavor for the case of eumelanin.

Hierarchical nanoporous solid base catalysts for biofuels

Novel macroporous solid bases have been developed as alternative clean technologies to existing commercial homogeneous catalysts for the production of biodiesel from triglycerides; the latter suffer process disadvantages including complex separation and associated saponification and engine corrosion, and are unsuitable for continuous operation. To this end, tuneable macroporous MgAl hydrotalcites have been prepared by an alkali-free route and characterised by TGA, XRD, SEM and XPS. The macropore architecture improves diffusion of bulky triglyceride molecules to the active base sites, increasing activity. Lamellar and macroporous hydrotalcites will be compared for the transesterification of both model and plant oil feedstocks, and structure-reactivity relations identified.

Biomimetic synthetic lubricants (Biosurfactants)

Poly(styrene-co-maleic anhydride) (PSMA) based copolymers are known to undergo conformational transition in response to environmental stimuli. This smart behaviour makes it possible to mimic the behaviour of native apoproteins. The primary aim of this study was to develop a better understanding of the structure-property relationships of various PSMA-based copolymers sought. The work undertaken in this thesis has revealed that the responsive behaviour of PSMA-based copolymers can be tailored by varying the molecular weight, hydrophobic (styrene) and hydrophilic (maleic acid) balance, and more so in the presence of additional hydrophobic, mono-partial ester moieties. Novel hydrophilic and hydrophobic synthetic surfactant protein analogues have successfully been prepared. These novel lipid solubilising agents possess a broad range of HLB (hydrophilic-lipophilic balance) values that have been estimated. NMR spectroscopy was utilised to confirm the structures for PSMA-based copolymers sought and proved useful in furthering understanding of the structure-property relationships of PSMA-based copolymers. The association of PSMA with the polar phospholipid, 2-dilauryl-sn-glycero-3- phosphocholine (DLPC) produces polymer-lipid complexes analogous to lipoprotein assemblies present in the blood plasma. NMR analysis reveals that the PSMA-based copolymers are not perfectly alternating. Regio-irregular structures, atactic and random monomer sequence distribution have been identified for all materials studied. Novel lipid solubilising agents (polyanionic surfactants) have successfully been synthesised from a broad range of PSMA-based copolymers with desired estimated HLB values that interact with polar phospholipids (DLPC/DPPC) uniquely. Very low static and dynamic surface tensions have been observed via the du Noϋy ring method and Langmuir techniques and correlate well with the estimated HLB values. Synthetic protein-lipid analogues have been successfully synthesised, that mimic the unique surface properties of native biological lubricants without the use of solvents. The novel PSMA-DLPC complexes have successfully been combined with hyaluronan (hyaluronic acid, HA). Today, the employment of HA is economically feasible, because it is readily available from bacterial fermentation processes in a thermally stable form - HyaCare®. The work undertaken in this thesis highlights the usage of HA in biolubrication applications and how this can be optimised and thus justified by carefully selecting the biological source, concentration, molecular weight, purity and most importantly by combining it with compatible boundary lubricating agents (polar phospholipids). Experimental evidence supports the belief that the combined HA and PSMA-DLPC complexes provide a balance of rheological, biotribological and surface properties that are composition dependent, and show competitive advantage as novel synthetic biological lubricants (biosurfactants).

Structural design of contact lens-based drug delivery systems; in vitro and in vivo studies of ocular triggering mechanisms

This study identifies and investigates the potential use of in-eye trigger mechanisms to supplement the widely available information on release of ophthalmic drugs from contact lenses under passive release conditions. Ophthalmic dyes and surrogates have been successfully employed to investigate how these factors can be drawn together to make a successful system. The storage of a drug-containing lens in a pH lower than that of the ocular environment can be used to establish an equilibrium that favours retention of the drug in the lens prior to ocular insertion. Although release under passive conditions does not result in complete dye elution, the use of mechanical agitation techniques which mimic the eyelid blink action in conjunction with ocular tear chemistry promotes further release. In this way differentiation between passive and triggered in vitro release characteristics can be established. Investigation of the role of individual tear proteins revealed significant differences in their ability to alter the equilibrium between matrix-held and eluate-held dye or drug. These individual experiments were then investigated in vivo using ophthalmic dyes. Complete elution was found to be achievable in-eye; this demonstrated the importance of that fraction of the drug retained under passive conditions and the triggering effect of in-eye conditions on the release process. Understanding both the structure-property relationship between drug and material and in-eye trigger mechanisms, using ophthalmic dyes as a surrogate, provides the basis of knowledge necessary to design ocular drug delivery vehicles for in-eye release in a controllable manner.

Mathematical Modeling, Music Literacy and Their Transmission in Fine Arts Education

Report published in the Proceedings of the National Conference on "Education and Research in the Information Society", Plovdiv, May, 2014

Culture, ethnicity and migration after communism:the Pontic Greeks

This book addresses the issue of emerging transnationalism in the conditions of post-socialism through focussing on migrants’ identity as a social construction resulting from their experience of the ‘transnational circuit of culture’ as well as from post-Soviet shifts in political and economic conditions in their home regions. Popov draws upon ethnographic research conducted among Greek transnational migrants living on the Black Sea coast and in the North Caucasus regions of Russia who have become involved in extensive cross-border migration between the former Soviet Union (the Russian Federation, Kazakhstan and Georgia) and Greece (as well as Cyprus). It is estimated that more than 150,000 former Soviet citizens of Greek origin have resettled in Greece since the late 1980s. Yet, many of those who emigrate do not cut their connections with the home communities in Russia but instead establish their own transnational circuit of travel between Greece and Russia. This study demonstrates how migrants employ their ethnicity as symbolic capital available for investment in profitable transnational migration. Simultaneously they rework their practices of family networking, property relations and political participation in a way which strengthens their attachment to the local territory. The findings presented in the book imply that the social identities, economic strategies, political practices and cultural representation of the Russian Greeks are all deeply embedded in the shifting social and cultural landscape of post-Soviet Russia and extensively influenced by the global movement of ideas, goods and people.

Bioactive sol-gel glasses at the atomic scale:the complementary use of advanced probe and computer modeling methods

Sol-gel-synthesized bioactive glasses may be formed via a hydrolysis condensation reaction, silica being introduced in the form of tetraethyl orthosilicate (TEOS), and calcium is typically added in the form of calcium nitrate. The synthesis reaction proceeds in an aqueous environment; the resultant gel is dried, before stabilization by heat treatment. These materials, being amorphous, are complex at the level of their atomic-scale structure, but their bulk properties may only be properly understood on the basis of that structural insight. Thus, a full understanding of their structure-property relationship may only be achieved through the application of a coherent suite of leading-edge experimental probes, coupled with the cogent use of advanced computer simulation methods. Using as an exemplar a calcia-silica sol-gel glass of the kind developed by Larry Hench, in the memory of whom this paper is dedicated, we illustrate the successful use of high-energy X-ray and neutron scattering (diffraction) methods, magic-angle spinning solid-state NMR, and molecular dynamics simulation as components to a powerful methodology for the study of amorphous materials.

Physicochemical properties of hydrogels for use in ophthalmology

This chapter deals with the physicochemical aspects of structure-property relationships in synthetic hydrogels, with particular reference to their application in optometry and ophthalmology. It demonstrates the ways in which the amount of water contained in the hydrogel network can be manipulated by changes in copolymer composition and illustrates the advantages and limitations imposed by use of water as a means of influencing surface, transport and mechanical properties of the gel. The chapter then illustrates how this basic understanding has formed a platform for the development of synthetic interpenetrating networks and macroporous materials, and of hybrids of natural and synthetic hydrogels. The behaviour of these more complex systems is not so centrally dominated by the equilibrium water content as is the case with homogeneous synthetic hydrogels, thus providing advantageous ways of extending the properties and applications of these interesting materials.

Négy jellegzetesség. A magyar fejlődés politikai gazdaságtani megközelítésben. 2. rész = Four characteristic features. Development in Hungary from the aspect of political economy - II.

A tulajdonviszonyok és intézmények átalakulását is a fokozatosság, a szerves fejlődés jellemzi; Magyarországon a hosszú reformszocialista fázist a politikai fordulat után sem követte ugrás a piacgazdaság felé, bár az átalakulás felgyorsult. A cikk a fokozatosság érvényesülését az értékesítési stratégia sokféle változatát alkalmazó, burjánzó privatizációban, az új vállalkozások keletkezésének folyamatában, a liberalizálás menetében és a jogi infrastruktúra változásában mutatja be. Elemzi az átmenet során megerősödő korporatista elemek hatását a magyar gazdaságpolitikára. Végül néhány összefoglaló megjegyzést fűz a magyar fejlődéshez a politikai gazdaságtan és a politikai filozófia szemszögéből. Az elmúlt harminc évben a mindenkori kormánynak jól érzékelhető preferenciája volt a radikális intézkedések elodázása, a társadalmi adósság felhalmozódásának vállalása a konfliktusok elkerülése érdekében. A szerző felhívja a figyelmet a különböző nemzedékek eltérő időpreferenciájára és az ezzel kapcsolatos etikai problémákra. Befejezésül a népszerűtlen intézkedéseket az állampolgárok nagy hányadának véleményével szemben is felvállaló kormányzás és a demokrácia viszonyáról szól. / === / Gradualism and organic development also distinguish the transformation of property relations and institutions. Hungary's long reform­socialist phase was not followed, after the political change, by a leap towards a market economy, although the transformation became faster. The article shows how gradualism applies to the proliferating of privatization, with its wide variety of selling strategies, to the foundation process of new firms, to the course of liberalization, and to change in the legal infrastructure. It analyses the effect on Hungarian economic policy of corporatist elements which strengthen during the transition. Finally, it makes some comments summing up Hungarian development in terms of political economy and political philosophy. The government at any time in the last thirty years showed an obvious preference for putting off radical measures and accepting an accumulation of social debt as a way of averting conflict. The article notes differences of time preference between generations and the ethical problems these raise. Finally, it makes remarks on the relationship between democracy and an administration intent on unpopular measures opposed by a high proportion of citizens.

Sociocultural complexities of ecosystem restoration: Remaking identity, landscape and belonging in the Florida Everglades

The Florida Everglades is a highly diverse socionatural landscape that historically spanned much of the south Florida peninsula. Today, the Florida Everglades is an iconic but highly contested conservation landscape. It is the site of one of the world's largest publicly funded ecological restoration programs, estimated to cost over $8 billion (U.S. GAO 2007), and it is home to over two million acres of federally protected lands, including the Big Cypress National Preserve and Everglades National Park. However, local people's values, practices and histories overlap and often conflict with the global and eco-centric values linked to Everglades environmental conservation efforts, sparking environmental conflict. My dissertation research examined the cultural politics of nature associated with two Everglades conservation and ecological restoration projects: 1) the creation and stewardship of the Big Cypress National Preserve, and 2) the Tamiami Trail project at the northern boundary of Everglades National Park. Using multiple research methods including ethnographic fieldwork, archival research, participant observation, surveys and semi-structured interviews, I documented how these two projects have shaped environmental claims-making strategies to Everglades nature on the part of environmental NGOs, the National Park Service and local white outdoorsmen. In particular, I examined the emergence of an oppositional white identity called the Gladesmen Culture. My findings include the following: 1) just as different forms of nature are historically produced, contingent and power-laden, so too are different claims to Everglades nature; 2) identity politics are an integral dimension of Everglades environmental conflicts; and 3) the Big Cypress region's history and contemporary conflicts are shaped by the broader political economy of development in south Florida. My dissertation concluded that identity politics, class and property relations have played a key, although not always obvious, role in shaping Everglades history and environmental claims-making, and that they continue to influence contemporary Everglades environmental conflicts.

Engineering metallic nanoparticles for enhancing and probing catalytic reactions

Recent developments in tailoring the structural and chemical properties of colloidal metal nanoparticles (NPs) have led to significant enhancements in catalyst performance. Controllable colloidal synthesis has also allowed tailor-made NPs to serve as mechanistic probes for catalytic processes. The innovative use of colloidal NPs to gain fundamental insights into catalytic function will be highlighted across a variety of catalytic and electrocatalytic applications. The engineering of future heterogenous catalysts is also moving beyond size, shape and composition considerations. Advancements in understanding structure-property relationships have enabled incorporation of complex features such as tuning surface strain to influence the behavior of catalytic NPs. Exploiting plasmonic properties and altering colloidal surface chemistry through functionalization are also emerging as important areas for rational design of catalytic NPs. This news article will highlight the key developments and challenges to the future design of catalytic NPs.

Argaric Sociology: Sex and Death

The detailed, rich and diverse Argaric funerary record offers an opportunity to explore social dimensions that usually remain elusive for prehistoric research, such us social rules on kinship rights and obligations, sexual tolerance and the role of funerary practices in preserving the economic and political organization. This paper addresses these topics through an analysis of the social meaning of Argaric double tombs by looking at body treatment and composition of grave goods assemblages according to gender and class affiliation. The Argaric seems to have been a conservative society, scarcely tolerant regarding homosexuality, and willing to celebrate ancestry associated to certain places as a means of asserting residence and property rights.

Fatalism, Attributions of Failure and Academic Performance in Mapuche and Non-Mapuche Chilean Students

This study investigated the role of fatalism as a cultural value orientation and causal attributions for past failure in the academic performance of high school students in the Araucania Region of Chile. Three thousand three hundred and fourty eight Mapuche and Non-Mapuche students participated in the study. Consistent with the Culture and Behavior model that guided the research, the test of causal models based on the analysis of structural equations show that academic performance is in part a function of variations in the level of fatalism, directly as well as indirectly through its influence in the attribution processes and failure-related emotions. In general, the model representing the proposed structure of relations among fatalism, attributions, and emotions as determinants of academic performance fit the data for both Mapuche and non-Mapuche students. However, results show that some of the relations in the model are different for students from these two ethnic groups. Finally, according to the results from the analysis of causal models, family SES appear to be the most important determinant of fatalism.

Koherentziazko diskurtso erlazioen detekzio automatikoa patroien bidez, XMLko erlazio-egiturak oinarri hartuta

[EU]Hizkuntzaren prozesamenduan testu koherenteetan kausa taldeko erlazioak (KAUSA, ONDORIOA eta HELBURUA) automatikoki hautematea eta bereiztea erabilgarria da galdera-erantzun automatikoko sistemak eraikitzerako orduan. Horretarako Egitura Erretorikoaren Teoria (Rhetorical Structure Theory, aurrerantzean RST) eta bere erlazioak erabiliko ditugu, corpus bezala RST Treebank -a (Iruskieta et al., 2013) hartuta, zientziako laburpen-testuz osatutako corpusa, hain zuzen ere. Corpus hori XML formatuan deskargatu eta hortik XPATH tresnaren bidez informazio garrantzitsuena eskuratzen dugu. Lan honek 3 helburu nagusi ditu: lehendabizi, kausa taldeko erlazioak elkarren artean bereiztea, bigarrenez, kausa taldeko erlazio hauek beste erlazio guztiekin bereiztea, eta azkenik, EBALUAZIOA eta INTERPRETAZIOA erlazioak bereiztea sentimendu analisian aplikatu ahal izateko. Ataza horiek egiteko, RhetDB tresnarekin eskuratu diren patroi ensaguratsuenak erabili eta bi aplikazio garatu ditugu. Alde batetik, bilatu nahi ditugun patroiak adierazi eta erlazio-egitura duen edonolako testuetan bilaketak egiten dituen bilatzailea, eta bestetik, patroi esanguratsuenak emanda erlazioak etiketatzen dituen etiketatzailea. Bi aplikazio hauek gainera, ahalik eta modu parametrizagarrienean erabiltzeko garatu ditugu, kodea aldatu gabe edonork erabili ahal izateko antzeko atazak egiteko. Etiketatzaileak ebaluatu ondoren, identifikatzeko erlaziorik errazena HELBURUA erlazioa dela ikusi dugu eta KAUSA eta ONDORIOA bereizteko arazo gehiago dauzkagula ere ondorioztatu dugu. Modu berean, EBALUAZIOA eta INTERPRETAZIOA ere elkarren artean bereiz dezakegula ikusi dugu.