Alkali-Activated Natural Pozzolan Concrete as New Construction Material

In the near future, geopolymers or alkali-activated cementitious materials will be used as new high-performance construction materials of low environmental impact with a reasonable cost. This material is a good candidate to partially replace ordinary portland cement (OPC) in concrete as a major construction material that plays an outstanding role in the construction industry of different structures. Geopolymer materials are inorganic polymers based on alumina and silica units; they are synthesized from a wide range of dehydroxylated alumina-silicate powders condensed with alkaline silicate in a highly alkaline environment. Geopolymeric materials can be produced from a wide range of alumina-silica, including natural products--such as natural pozzolan and metakaolin--or coproducts--such as fly ash (coal and lignite), oil fuel ash, blast furnace or steel slag, and silica fume--and provide a route toward sustainable development. Using lesser amounts of calcium-based raw materials, lower manufacturing temperature, and lower amounts of fuel result in reduced carbon emissions for geopolymer cement manufacture up to 22 to 72% in comparison with portland cement. A study has been done by the authors to investigate the intrinsic nature of different types of Iranian natural pozzolans to determine the activators and methods that could be used to produce a geopolymer concrete based on alkali-activated natural pozzolan (AANP) and optimize mixture design. The mechanical behavior and durability of these types of geopolymer concrete were investigated and compared with normal OPC concrete mixtures cast by the authors and also reported in the literature. This paper summarizes the main conclusions of the research regarding pozzolanic activity, activator properties, engineering and durability properties, applications and evaluation of carbon footprint, and cost for AANP concrete.

Tailoring Magnetic, Mechanical and Dielectric Properties of Magnetorheological Elastomers based on Natural Rubber and Iron by Magnetic Field Assisted Curing for Possible Applications

If magnetism is universal in nature, magnetic materials are ubiquitous. A life without magnetism is unthinkable and a day without the influence of a magnetic material is unimaginable. They find innumerable applications in the form of many passive and active devices namely, compass, electric motor, generator, microphone, loud speaker, maglev train, magnetic resonance imaging, data recording and reading, hadron collider etc. The list is endless. Such is the influence of magnetism and magnetic materials in ones day to day life. With the advent of nanoscience and nanotechnology, along with the emergence of new areas/fields such as spintronics, multiferroics and magnetic refrigeration, the importance of magnetism is ever increasing and attracting the attention of researchers worldwide. The search for a fluid which exhibits magnetism has been on for quite some time. However nature has not bestowed us with a magnetic fluid and hence it has been the dream of many researchers to synthesize a magnetic fluid which is thought to revolutionize many applications based on magnetism. The discovery of a magnetic fluid by Jacob Rabinow in the year 1952 paved the way for a new branch of Physics/Engineering which later became magnetic fluids. This gave birth to a new class of material called magnetorheological materials. Magnetorheological materials are considered superior to electrorheological materials in that magnetorheology is a contactless operation and often inexpensive.Most of the studies in the past on magnetorheological materials were based on magnetic fluids. Recently the focus has been on the solid state analogue of magnetic fluids which are called Magnetorheological Elastomers (MREs). The very word magnetorheological elastomer implies that the rheological properties of these materials can be altered by the influence of an external applied magnetic field and this process is reversible. If the application of an external magnetic field modifies the viscosity of a magnetic fluid, the effect of external magnetic stimuli on a magnetorheological elastomer is in the modification of its stiffness. They are reversible too. Magnetorheological materials exhibit variable stiffness and find applications in adaptive structures of aerospace, automotive civil and electrical engineering applications. The major advantage of MRE is that the particles are not able to settle with time and hence there is no need of a vessel to hold it. The possibility of hazardous waste leakage is no more with a solid MRE. Moreover, the particles in a solid MRE will not affect the performance and durability of the equipment. Usually MR solids work only in the pre yield region while MR fluids, typically work in the post yield state. The application of an external magnetic field modifies the stiffness constant, shear modulus and loss modulus which are complex quantities. In viscoelastic materials a part of the input energy is stored and released during each cycle and a part is dissipated as heat. The storage modulus G′ represents the capacity of the material to store energy of deformation, which contribute to material stiffness. The loss modulusG′′ represents the ability of the material to dissipate the energy of deformation. Such materials can find applications in the form of adaptive vibration absorbers (ATVAs), stiffness tunable mounts and variable impedance surfaces. MREs are an important material for automobile giants and became the focus of this research for eventual automatic vibration control, sound isolation, brakes, clutches and suspension systems

Radiopacity and Chemical resistance of Elastomer-Barium sulphate nanocomposites

The Human race of our century is in gluttonous search for novel engineering products which led to a skyrocketed progress in research and fabrication of filled polymers. Recently, a big window has been opened up for speciality polymers especially elastomers with promising properties. Among the many reasons why rubbers are widely used in the process industries, three are considered as important. Firstly, rubbers operate in a variety of environments and possess usable ranges of deformity and durability and can be exploited through suitable and more or less conventional equipment design principles. Secondly, rubber is an eminently suitable construction material for protection against corrosion in the chemical plant and equipment against various corrosive chemicals as, acids and alkalies and if property tailored, can shield ionising radiations as X-rays and gamma rays in medical industry, with minimum maintenance lower down time, negligible corrosion and a preferred choice for aggressive corroding and ionising environment. Thirdly, rubber can readily and hastily, and at a relatively lower cost, be converted into serviceable products, having intricate shapes and dimensions. In a century’s gap, large employment of flexible polymer materials in the different segments of industry has stimulated the development of new materials with special properties, which paved its way to the synthesis of various nanoscale materials. At nano scale, one makes an entry into a world where multidisciplinary sciences meet and utilises the previously unapproached infinitesimal length scale, having dimension which measure upto one billionth of a meter, to create novel properties. The nano fillers augment the elastomers properties in an astonishing fashion due to their multifunctional nature and unprecedented properties have been exhibited by these polymer-nanocomposites just to beat the shortcomings of traditional micro composites. The current research aims to investigate the possibility of using synthesised nano barium sulphate for fabricating elastomer-based nanocomposites and thereby imparting several properties to the rubber. In this thesis, nano materials, their synthesis, structure, properties and applications are studied. The properties of barium sulphate like chemical resistance and radiopacity have been utilized in the present study and is imparted to the elastomers by preparing composites.

Evaluation and Testing of a Lightweight Fine Aggregate Concrete Bridge Deck in Buchanan County, Iowa, TR-648, 2016

Internal curing is a relatively new technique being used to promote hydration of Portland cement concretes. The fundamental concept is to provide reservoirs of water within the matrix such that the water does not increase the initial water/cementitious materials ratio to the mixture, but is available to help continue hydration once the system starts to dry out. The reservoirs used in the US are typically in the form of lightweight fine aggregate (LWFA) that is saturated prior to batching. Considerable work has been conducted both in the laboratory and in the field to confirm that this approach is fundamentally sound and yet practical for construction purposes. A number of bridge decks have been successfully constructed around the US, including one in Iowa in 2013. It is reported that inclusion of about 20% to 30% LWFA will not only improve strength development and potential durability, but, more importantly, will significantly reduce shrinking, thus reducing cracking risk. The aim of this work was to investigate the feasibility of such an approach in a bridge deck.

Creep deflection of low-strength reinforced concrete flexural members strengthened with carbon fiber composite sheets

The low-strength concrete is defined as a concrete where the compressive cubic strength is less than 15 MPa. Since the beginning of the last century, many low-strength concrete buildings and bridges have been built all over the world. Being short of deeper study, composite sheets are prohibited in strengthening of low-strength reinforced concrete members (CECS 146; ACI 440). Moreover, there are few relevant information about the long-term behavior and durability of strengthened RC members. This fact undoubtedly limits the use of the composite materials in the strengthening applications, therefore, it is necessary to study the behaviours of low-strength concrete elements strengthened with composite materials (FRP) for the preservation of historic constructions and innovation in the strengthening technology. Deformability is one of criteria in the design of concrete structures, and this for functionality, durability and aesthetics reasons. Civil engineer possibly encounters more deflection problems in the structural design than any other type of problem. Many materials common in structural engineering such as wood, concrete and composite materials, suffer creep; if the creep phenomenon is taken into account, checks for serviceability limit state criteria can become onerous, because the creep deformation in these materials is in the same order of magnitude as the elastic deformation. The thesis presents the results of an experimental study on the long-term behavior of low-strength reinforced concrete beams strengthened with carbon fiber composite sheets (CFRP). The work has investigated the accuracy of the long-term deflection predictions made by some analytical procedures existing in literature, as well as by the most widely used design codes (Eurocode 2, ACI-318, ACI-435).

Perfis de Redes Sociais Pessoais de Idosos com e Sem Apoio de Respostas Sociais: um contributo para o desenvolvimento de tipologias no Diagnóstico Social

Sendo um dos objetivos do Serviço Social a promoção do bem-estar social, e considerando a relevância das redes sociais pessoais e do suporte social no bem-estar das pessoas idosas, o presente estudo analisa perfis de redes sociais pessoais de idosos, tendo em conta as suas características estruturais, funcionais e relacionais-contextuais, na perspectiva do Serviço Social sistémico. Na última etapa da vida identificam-se na rede social de um individuo vários determinantes com efeitos cumulativos que favorecem o estreitamento das redes sociais, sendo os contextos de vida, as necessidades de apoio de respostas sociais e a institucionalização, fatores relevantes para a investigação. A investigação quantitativa, utilizou um inquérito por questionário para caracterizar sociodemograficamente a amostra e o Instrumento de Análise de Rede Social Pessoal (Guadalupe, 2009) para caracterizar a rede nas suas dimensões e características, privilegiando-se uma análise bivariada das variáveis. A amostra é composta por 317 idosos com idade igual ou superior a 65 anos. Comparámos três subamostras: 209 idosos que não usufruem do apoio de respostas sociais (65,9%), sendo estes maioritariamente de sexo feminino, casado(a)s ou a viver em união de facto e com média de 75 anos; 71 idosos que usufruem de apoio de respostas sociais (22,4%), na sua maioria de sexo feminino, viúvo(a)s e com 80 anos de média de idade; 37 idosos institucionalizados em Lar (11,7%), mulheres na sua maioria, viúvo(a)s, com média de 83 anos. A hipótese inicial do nosso estudo era a existência de três perfis distintos nas redes sociais pessoais de idosos, conforme a sua relação com as respostas sociais, no entanto, concluiu-se que existe um padrão comum nas redes sociais destes idosos, quer a nível estrutural, como a nível funcional ou contextual. Todavia, identificamos algumas diferenças significativas (p < 0,041) entre os perfis explorados, na composição das redes, na reciprocidade de apoio, na satisfação da rede, na densidade, na frequência de contactos, na distância geográfica e na durabilidades das relações. O estudo constitui-se como um contributo para o Serviço Social, na medida em que oferece conhecimento sobre as redes sociais dos idosos em diferentes contextos de vida, não oferecendo, no entanto, uma categorização que possibilite a construção cabal de tipologias, mas antes, fornece uma base orientadora da avaliação das redes sociais pessoais e de suporte social de idosos para o diagnóstico social. / Being one of Social Work goals the promotion of social well-being, and considering the relevance of personal social networks and social support in the well-being of the elderly, the present study analyzes personal social network’s profiles of elderly people, taking into account their structural, functional and relational-contextual characteristics, in a Social Work systemic perspective. In the last stage of life are identified in an individual's various social network determinants with cumulative effects favouring the narrowing of social networks, being life contexts, the support needs of social responses and institutionalization, relevant factors to the investigation. Our quantitative research used a survey to characterize socially and demographically the sample and the Personal Social Network Analysis Tool (Guadalupe, 2009) to characterize the network in its dimensions and characteristics, using a bivariate analysis of the variables. The sample is composed of 317 elderly aged 65 years old or more. We compared three sub-samples: 209 seniors who do not have the support of social services (65.9%), mostly female, married or cohabiting and with an average of 75 years old; 71 seniors who have support of social services (22.4%), mostly women, widowed and with 80 years of average age; 37 institutionalized elderly (11.7%), mostly women, widowed, with an average age of 83 years. The initial hypothesis of our study was the existence of three distinct personal profiles on social networks, according to their relationship to the social services, however, we have concluded that there is a common pattern in social networks of these elderly, at their structural, functional or contextual level. However, we identified some significant differences (p < 0.041) between the explored profiles, in the composition of networks, support reciprocity, network satisfaction, density, frequency of contacts, geographical distance and durability of relations. The study is a contribution to Social Work, insofar as it provides knowledge about personal social networks of the elderly in different life contexts, not offering, however, a fully categorization that allows the construction of typologies, but rather, provides guidance lines in the evaluation of personal social networks and social support of the elderly to the social diagnosis.

Redes Sociais Pessoais e Mobilidade em Idosos

Objetivos: A investigação tem como objetivo geral analisar a associação entre a mobilidade nos idosos e as características estruturais, funcionais e relacionais-contextuais das suas redes sociais pessoais. Metodologia: No nosso estudo utilizámos o Instrumento de Análise da Rede Social Pessoal, IARSP, versão idosos (IARSP Idosos de Guadalupe & Vicente, 2012; Guadalupe, 2009), que permite caracterizar a rede social pessoal do individuo e uma questão do WHOQOL (OMS; Canavarro et al., 2006) para avaliar a perceção de mobilidade. Participantes: A amostra é constituída por 446 idosos com idades compreendidas entre os 65 anos e os 98 anos. Os participantes são na sua maioria do sexo feminino (63,9%; n = 285), casados (51,6%; n = 230) e com escolaridade (65,9%; n = 294). Resultados: Verifica-se que são os idosos do sexo feminino, os casados e com escolaridade, aqueles que apresentam uma média mais elevada de mobilidade percebida. Constata-se que existe uma maior proporção de idosos cuja mobilidade é “boa ou muito boa” (48,2%; n = 215) em comparação com os que têm uma mobilidade “nem boa nem má” (26,5%; n = 118) e com os que a mobilidade é “má ou muito má” (25,3%; n = 113). Quanto às características estruturais, os idosos que apresentam melhor mobilidade percebida têm uma média mais elevada na proporção das relações familiares nas redes (M = 77%), quanto às características funcionais, na companhia social (M = 2,37), apesar de não existirem diferenças significativas, e na reciprocidade de apoio (M = 3,53; p= 0,002), e consideram estar muito satisfeitos com a rede (M = 2,87, p= 0,059), quando tais características comparadas com as dos idosos com pior mobilidade. Verificam-se também diferenças entre as subamostras quer no apoio material e instrumental (M = 2,30; p = 0,013) e no apoio informativo (M = 2,44; p = 0,001), registando o grupo das pessoas com pior mobilidade as médias mais baixas. Quanto às características relacionais contextuais, na durabilidade das relações, os sujeitos com mobilidade “má ou muito má” apresentam uma média mais elevada (M = 42,41 anos; p = 0,025). Conclusão: Segundo a pior ou melhor mobilidade, é nas características funcionais que se assinalam as principais diferenças estatisticamente significativas, o que nos permitem afirmar uma associação entre mobilidade nos idosos e as relações interpessoais, pelo conteúdo das relações e pelo apoio que percecionam. Concluímos que os idosos que se consideram com melhor mobilidade apresentam, na generalidade, características de rede social mais positivas quando comparados com os que têm menor mobilidade percebida. /Objectives: The main goal of the research is to analyze the association between mobility in the elderly and the structural, functional and relational-contextual characteristics of their personal social networks. Methodology: In our study, we used the Social Personal Network Assessment Tool – IARSP , elderly version (IARSP-Idosos of Guadalupe Vicente, 2012; Guadalupe, 2009), enabling an individual's personal social network and a question of WHOQOL (WHO; Canavarro and such, 2006) to evaluate their perception of functionality of mobility. Participants: The study has 446 elderly participants aged between 65 years and 98 years. Participants are mostly female (63,9%; N = 285), married (51,6%; N = 230) and with education (65,9%; N = 294). Results: We found that older women, married and with education are those with a better mobility. It is noted that there is a greater proportion of elderly people whose mobility is "good or very good" (48.2%, n = 215) compared to those with a mobility "neither good nor bad" (26.5%, n = 118) and the mobility is "bad or very bad" (25.3%; n = 113). Regarding the structural characteristics, seniors who have better perceived mobility have a higher average in the proportion of family relationships in networks (M = 77%; p 0,331), and for the functional characteristics as social company (2, 37; p = 0,418), reciprocal support (3.53; p = 0.002), and satisfaction with their network (M = 2.87; p = 0.059) when these characteristics are compared with those of older people with poor mobility. Exist also statistically significant differences between subsamples either in the material and instrumental support (M = 2.30; p = 0.013) and informational support (M = 2.44; p = 0.001), recording the group of people with poorest mobility. For the relational and contextual characteristics, individuals with mobility "bad or very bad" have a higher mean durability of relationships (M = 42.41; p = 0.025). Conclusion: According to better or worse mobility, the functional characteristics indicates major differences between subsamples, that allow us to assert an association between mobility in the elderly and the content of interpersonal relationships, as well as the perception of support. We conclude that the elderly who consider themselves to have better mobility in general, have more positive social networking features when compared to those with lower perceived mobility.

Redes Sociais Pessoais de Idosos com e sem Filhos

Objetivos: O presente estudo tem como objectivo analisar as redes sociais e pessoais de idosos portugueses com filhos e sem filhos, relativamente às características estruturais, funcionais e relacionais-contextuais. Metodologia: Para a avaliação das variáveis em estudo foram utilizados: o Instrumento de Análise da Rede Social Pessoal, versão para idosos (IARSP – Idosos) (Guadalupe, 2010; Guadalupe & Vicente, 2012) para avaliar as dimensões da rede social pessoal; um inquérito por questionário para caracterização da amostra a nível sociodemográfico e sociofamiliar. Participantes: A amostra é constituída por 418 idosos, com uma média de idades de 76 anos (DP=7,62), entre os 65 anos e os 98 anos, maioritariamente do sexo feminino (63,9%), casados ou em união facto (51,0%) e com escolaridade (63,9,1%). A maioria dos idosos inquiridos vive com agregado familiar (80,4%) em zonas rurais (64,8) e não usufrui de qualquer tipo de apoio de resposta social (71,5%). Resultados: Os idosos com filhos são maioritários (n=364; 87,1%) e os sem filhos os minoritários (n=54; 12,9%) na nossa amostra. Dos que têm filhos, 29,9% (109) têm filhos únicos e 70,1% (255) têm mais do que um filho (67% com 1 ou 2 filhos), sendo os filhos maioritariamente de ambos os sexos (n=158; 43,4%). Os resultados sugerem que o facto de os idosos terem ou não terem filhos reflete-se sobretudo em diferenças nas características estruturais das redes. Os idosos com filhos apresentam uma média mais elevada no tamanho da rede, na proporção das relações de familiares, e satisfação da rede e reciprocidade de apoio (p ≤ 0,001), a nível das características funcionais. Já relativamente à proporção das relações de amizade, vizinhança na rede, são os idosos sem filhos que apresentam uma média substantivamente mais elevada (p ≤ 0,003) do que a outra subamostra, apresentando também uma maior durabilidade das relações interpessoais (p < 0,03). As correlações entre o número total de filhos/as com as características estruturais e funcionais da rede, indicam-nos que quanto maior é o número de filhos maior é o tamanho da rede, a proporção das relações familiares, o apoio emocional, a reciprocidade de apoio, a satisfação com a rede e com o suporte social. Conclusões: O nosso estudo revela que as redes sociais pessoais dos idosos diferenciam-se a nível estrutural segundo o facto de terem ou não filhos, mas também nalgumas variáveis funcionais. Os idosos com filhos apresentam redes mais alargadas e muito centradas nas relações familiares na rede (sensivelmente menos um terço) do que os idosos sem filhos. Os últimos apresentam redes menores (com cerca de 2 pessoas a menos) e mais investidas nas relações de amizade e de vizinhança (com proporções que representam mais do dobro destes vínculos). / Goals: The present study has the purpose to analyze the personal social networks of Portuguese elder with our without sons/daughters, in their structural, functional and contextual relations. Methodology: We used for the evaluation of the variables: The Personal Social Network Analysis Tool, regarding elderly people (IARSP – elderly people) (Guadalupe, 2010; Guadalupe & Vicente, 2012), to evaluate the personal social network dimensions; a survey through an inquiry to characterize the sample at sociodemographic and at sociofamily level. Participants: The sample includes 418 elderly with an average age of 76 years old (DP = 7,62) between 65 and 98 years old, mainly women (63,9%), married or living as a couple (51,0%) with education (63,9,1%). Most of the elderly people who answered the survey live in family household (80,4%) in rural areas (64,8) and do not benefit from any type of social services support (71,5%). Results: The majority is elderly people with sons/daughters (n=364, 87,1%) and the ones without are the minority (n= 54, 12,9%) in our sample. Within those who are parents, 29,9% (109) have only one child and 70,1% (255) have more than one child (67% with 1 or 2), and the children are mainly of both sexes (n= 158; 43,4%). The results suggest that the fact that the elderly have or not have children is reflected especially in differences in the structural characteristics of the networks. Elderly people with children have a higher average in the network size, in the proportion of family relationships, and satisfaction of the network and reciprocal support (p ≤ 0,001). Regarding the proportion of friendly relations, network neighborhood, are the elderly without children who have a substantially higher mean (p ≤ 0,003) than the other subsample, also featuring improved durability of interpersonal relationships (p < 0,003). The correlations between the total number of children/with the structural and functional characteristics of the network, indicate that the greater the number of children, the greater the size of the network, the proportion of family relationships, emotional, support, reciprocity support and satisfaction with social network. Conclusion: Our study reveals that the personal social networks of the elderly differ in the structural level, according to whether they have sons/daughters or not, but also in some functional variables. The elderly with children have networks much more broader and centered on family relationships (roughly one-third) than elderly without children. These elderly without children have smaller networks (about 2 fewer people) and more centered in relations of friendship and neighborhood (with proportions that are more than the double compared to the other subsample).

O Contrato Psicológico e a Influência do Tipo de Vínculo: empenhamento na carreira e commitment organizacional

As transformações nas relações contratuais e na ligação psicológica do indivíduo à organização motivaram a realização do presente estudo. Os seus objectivos centrais consistiram em, por um lado, analisar a influência do tipo de vínculo na formação do Contrato Psicológico dos indivíduos com a organização e, por outro lado, compreender a relação do Contrato Psicológico com o Empenhamento na Carreira e com o Commitment Organizacional, e o que poderá distinguir estas relações. A metodologia apoiou-se num questionário, aplicado a uma amostra de 102 profissionais com vínculos de trabalho estáveis e instáveis, de diferentes organizações, ramos profissionais e sectores de actividade. A amostra é proporcional e representativa. (a) Os resultados demonstram que os profissionais prestadores de serviço são o único caso em que o tipo de vínculo tem influência significativa sobre a formação do Contrato Psicológico, percepcionando uma ligação transaccional com a organização. (b) Em contrapartida, provam que uma maior ou menor estabilidade contratual não tem influência significativa sobre os Contratos Psicológicos relacional ou equilibrado. (c) Os resultados sugerem ainda que o Contrato Psicológico está mais directamente relacionado com o Empenhamento na Carreira do que com o Commitment Organizacional. O Contrato Psicológico apresenta correlações fortes com o Empenhamento na Carreira e a consequente utilização de comportamentos individuais de Gestão de Carreira, sendo esta mais significativa nas ligações psicológicas de tipo equilibrado e relacional. No que respeita ao Commitment Organizacional, este não apresenta relação significativa com o Contrato Psicológico mas verificamos a existência de focus de Commitment Organizacional. Os resultados comprovam que o Contrato Psicológico se correlaciona com a sua dimensão normativa. As conclusões evidenciam o incremento das relações transaccionais, motivadas pela menor durabilidade dos vínculos e o desenvolvimento de reduzidas expectativas na relação com a organização e para o carácter individual e circunstancial das ligações psicológicas, que já não obedecem a um padrão tipo. Perante cenários de grande instabilidade, independentemente do Contrato Psicológico estabelecido, a preocupação com a Carreira ganha relevância. Os profissionais actuais tendem a transferir a preocupação com o vínculo e a segurança no emprego para questões de carreira, segurança de empregabilidade e sucesso psicológico. Observa-se que a lealdade à organização é na maior parte dos casos transferida para a lealdade à carreira. / Transformations in contractual relationships and in the psychological connection of an individual to an organization have motivated the execution of the present study. The main objectives of this study were, on the one hand, to analyze the influence of the type of contractual bond in the shaping of the psychological contract of individuals with an organization, and, on the other hand, to understand the relationship between the psychological contract, the career commitment and the organizational commitment, to understand subsequently what may distinguish these relationships. The methodology was supported by a questionnaire, which was applied to a sample of 105 professionals with both stable and unstable contractual bonds in different organizations, professional lines of business and activity sectors. The sample is proportional and representative. (a) The results demonstrate that service providing professionals are the only case in which the type of contractual bond has a significant influence on the shaping of a psychological contract, perceived as a transactional connection with the organization. (b) On the other hand a higher or lower contractual stability has no significant influence or relationship with the psychological contract, relational or balanced. (c) The results also suggest that the psychological contract is more directly related to career commitment than to organizational commitment. The psychological contract shows a strong correlation with the career commitment and the consequent use of the individual behaviour of Career Management, with the latter being more significant to a balanced and relational type of psychological connection. In regard to Organizational Commitment, this presents no significant relationship with the psychological contract but the focus on the organizational commitment is verified. The results also show that the psychological contract is correlated with its normative dimension. The increase in transactional relationships are evident. This is driven by reduction of the durability of contractual bonds and the development of reduced expectations in relation to the organization and the individual character and circumstance of the psychological connections, which no longer conform to a standard type. Scenarios of great instability, regardless of the psychological contract established, cause the concern with career to gain relevance. Current professionals tend to transfer their concerns about contractual bonds and job security to career issues, job security and psychological success. It can also be seen that loyalty to the organization is, in most cases, transferred to loyalty to the career.

Hallux rigidus: Arthroplasty or arthrodesis. What technique produces better results?

Hallux rígidus (HR) affects the first metatarsophalangeal joint (MTPJ) between 35% and 60% of the population over 65 years and there are multiple ways of treatment. Depending on the radiological stage where you find the deformity determines the procedure to be performed; in the early stages cheilectomy techniques and corrective osteotomy is performed while the more advanced ratings, the surgeon chooses destructive techniques considered as arthrodesis and arthroplasty. This final of degree project aims to focus on 1 MTPJ destructive techniques to clarify which of the procedures generates better results by a number of parameters; outcomes of the American Orthopaedic Foot scale and Ankle Society Hallux metatarsophalangeal Interphalangeal-scale (AOFAS), range of motion (ROM) of the 1ºAMTF, radiological classification. As for the implant arthroplasty technique, this article offers information on material and design that generates better relating to patient characteristics such as age, inflammatory joint diseases, viability and durability of the implant results. The conclusion from this review is that the values obtained in the arthrodesis according AOFAS decrease due to loss of mobility, but both techniques have similar values of effectiveness and concludes with the decision that the technique used is determined taking into account various factors and patient characteristics. Keywords: Hallux rígidus; (Hallux Rígidus) and surgery treatment; Hallux Rígidus arthrodesis; Hallux Rígidus arthroplasty; Hallux Rígidus (arthroplasty and arthrodesis).

Evaluation of fly ash in water reduced paving mixtures, 1984

Fly ash was used to replace 15% of the cement in C3WR and C6WR concrete paving mixes containing ASTM C494 Type A water reducin9 admixtures. Two Class C ashes and one Class F ash from Iowa approved sources were examined in each mix. When Class C ashes were used they were substituted on the basis of 1 pound of ash added for each pound of cement deleted. When Class F was used it was substituted on the basis of 1.25 pounds of ash added for each pound of cement deleted. Compressive strengths of the water reduced mixes, with and without fly ash, were determined at 7, 28, and 56 days of age. In every case except one the mixes containing the fly ash exhibited higher strengths than the same concrete mix without the fly ash. An excellent correlation existed between the C3WR and C6WR mixes both with and without fly ash substitutions. The freeze-thaw durability of the concrete studied was not affected by presence or absence of fly ash. The data gathered suggests that the present Class C water reduced concrete paving mixes can be modified to allow the substitution of 15% of the cement with an approved fly ash.

Valves cardiaques par génie tissulaire - Simplification des essais et concept tubulaire

Les substituts valvulaires disponibles actuellement comportent encore plusieurs lacunes. La disponibilité restreinte des allogreffes, les risques de coagulation associés aux valves mécaniques et la durabilité limitée des bioprothèses en tissu animal sont toutes des problématiques que le génie tissulaire a le potentiel de surmonter. Avec la méthode d’auto-assemblage, le seul support des cellules consiste en leur propre matrice extracellulaire, permettant la fabrication d’un tissu entièrement libre de matériau exogène. Ce projet a été précédé par ceux des doctorantes Catherine Tremblay et Véronique Laterreur, ayant respectivement développé une méthode de fabrication de valves moulées par auto-assemblage et une nouvelle version de bioréacteur. Au cours de cette maîtrise, le nouveau bioréacteur a été adapté à une utilisation stérile avec des tissus vivants et la méthode de fabrication de valves moulées a été modifiée puis éprouvée avec la production de 4 prototypes. Ces derniers n’ont pas permis d’obtenir des performances satisfaisantes en bioréacteur, motivant la conception d’une nouvelle méthode. Plutôt que de tenter de répliquer la forme native des valves cardiaques, des études récentes ont suggéré une géométrie tubulaire. Cela permettrait une fabrication simplifiée, une implantation rapide, et un encombrement minimal en vue d’opérations percutanées. Cette approche minimaliste s’accorde bien avec la méthode d’auto-assemblage, qui a déjà été utilisée pour la production de vaisseaux de petits diamètres. Un total de 11 tubes ont été produits par l’enroulement de feuillets fibroblastiques auto-assemblés, puis ont été transférés sur des mandrins de diamètre inférieur, leur permettant de se contracter librement. La caractérisation de deux tubes contrôles a démontré que cette phase de précontraction était bénéfique pour les propriétés du tissu en plus de prévenir la contraction en bioréacteur. Les prototypes finaux pouvaient supporter un écoulement physiologique pulmonaire. Cette nouvelle méthode montre que le procédé d’auto-assemblage a le potentiel d’être utilisé pour fabriquer des valves cardiaques tubulaires.

Avaliação do ciclo de vida de um pavimento flutuante de cortiça

A consciencialização ambiental vem assumindo um papel preponderante na construção civil. Nesse sentido, o desenvolvimento de materiais sustentáveis e ecológicos é essencial para a satisfação de fabricantes e consumidores, respeitando diversos requisitos: níveis reduzidos de poluição e toxicidade, durabilidade dos materiais, possibilidade de reutilização e/ou reciclagem, a proveniência das matérias-primas e a possibilidade de contaminação do ar no interior dos edifícios. As declarações ambientais de produto (DAP) permitem informar o consumidor do desempenho ambiental dos materiais dos produtos. Assim, ao longo de todo o processo de fabrico são registados os consumos de recursos e emissões ambientais e, através da metodologia de avaliação de ciclo de vida, é quantificada a contribuição resultante para impactes ambientais. Esta dissertação visa analisar os possíveis impactes ambientais no decurso do processo de produção de um pavimento flutuante de cortiça, constituído por cortiça, High Density Fibreboard (HDF) e acabamento de superfície, denominado Artcomfort Floating NPC e elaborar de um relatório de suporte, que servirá de base para a DAP do pavimento Artcomfort Floating NPC do sistema do Institut Bauen und Umwelt (IBU). Esta dissertação inclui um relatório de fundo, para a avaliação do ciclo de vida do pavimento flutuante Artcomfort Floating NPC da empresa Amorim Revestimentos, que servirá de base para a elaboração da declaração ambiental de produto (DAP) do mesmo. Para tal, recorreu-se ao software SimaPro para análise dos impactes ambientais das várias fases do processo de fabrico do pavimento em estudo, sendo as fases consideradas, a produção da camada base de cortiça aglomerada, camada backing de cortiça aglomerada, montagem da sanduiche, placa pintada, placa acabada e corte e embalagem. A fase que tem maior contribuição para os impactes ambientais do processo de fabrico do produto, em todas as categorias de impacte analisadas, com exceção da depleção dos recursos abióticos sem combustíveis fósseis, foi a fase de montagem da sanduiche.

In-vitro Clot Formation and Failure

Thesis (Master's)--University of Washington, 2016-08

Développement et caractérisation de nouveaux nanocomposites polymères électriquement conductueurs pour plaques bipolaires de piles à combustible à membrane échangeuse de protons, PEMFC

Face à la diminution des ressources énergétiques et à l’augmentation de la pollution des énergies fossiles, de très nombreuses recherches sont actuellement menées pour produire de l’énergie propre et durable et pour réduire l’utilisation des sources d’énergies fossiles caractérisées par leur production intrinsèque des gaz à effet de serre. La pile à combustible à membrane échangeuse de protons (PEMFC) est une technologie qui prend de plus en plus d’ampleur pour produire l’énergie qui s’inscrit dans un contexte de développement durable. La PEMFC est un dispositif électrochimique qui fonctionne selon le principe inverse de l’électrolyse de l’eau. Elle convertit l’énergie de la réaction chimique entre l’hydrogène et l’oxygène (ou l’air) en puissance électrique, chaleur et eau; son seul rejet dans l’atmosphère est de la vapeur d’eau. Une pile de type PEMFC est constituée d’un empilement Électrode-Membrane-Électrode (EME) où la membrane consiste en un électrolyte polymère solide séparant les deux électrodes (l’anode et la cathode). Cet ensemble est intégré entre deux plaques bipolaires (BP) qui permettent de collecter le courant électrique et de distribuer les gaz grâce à des chemins de circulation gravés sur chacune de ses deux faces. La plupart des recherches focalisent sur la PEMFC afin d’améliorer ses performances électriques et sa durabilité et aussi de réduire son coût de production. Ces recherches portent sur le développement et la caractérisation des divers éléments de ce type de pile; y compris les éléments les plus coûteux et les plus massifs, tels que les plaques bipolaires. La conception de ces plaques doit tenir compte de plusieurs paramètres : elles doivent posséder une bonne perméabilité aux gaz et doivent combiner les propriétés de résistance mécanique, de stabilité chimique et thermique ainsi qu’une conductivité électrique élevée. Elles doivent aussi permettre d’évacuer adéquatement la chaleur générée dans le cœur de la cellule. Les plaques bipolaires métalliques sont pénalisées par leur faible résistance à la corrosion et celles en graphite sont fragiles et leur coût de fabrication est élevé (dû aux phases d’usinage des canaux de cheminement des gaz). C’est pourquoi de nombreuses recherches sont orientées vers le développement d’un nouveau concept de plaques bipolaires. La voie la plus prometteuse est de remplacer les matériaux métalliques et le graphite par des composites à matrice polymère. Les plaques bipolaires composites apparaissent attrayantes en raison de leur facilité de mise en œuvre et leur faible coût de production mais nécessitent une amélioration de leurs propriétés électriques et mécaniques, d’où l’objectif principal de cette thèse dans laquelle on propose: i) un matériau nanocomposite développé par extrusion bi-vis qui est à base de polymères chargés d’additifs solides conducteurs, incluant des nanotubes de carbone. ii) fabriquer un prototype de plaque bipolaire à partir de ces matériaux en utilisant le procédé de compression à chaud avec un refroidissement contrôlé. Dans ce projet, deux polymères thermoplastiques ont été utilisés, le polyfluorure de vinylidène (PVDF) et le polyéthylène téréphtalate (PET). Les charges électriquement conductrices sélectionnées sont: le noir de carbone, le graphite et les nanotubes de carbones. La combinaison de ces charges conductrices a été aussi étudiée visant à obtenir des formulations optimisées. La conductivité électrique à travers l’épaisseur des échantillons développés ainsi que leurs propriétés mécaniques ont été soigneusement caractérisées. Les résultats ont montré que non seulement la combinaison entre les charges conductrices influence les propriétés électriques et mécaniques des prototypes développés, mais aussi la distribution de ces charges (qui de son côté dépend de leur nature, leur taille et leurs propriétés de surface), avait aidé à améliorer les propriétés visées. Il a été observé que le traitement de surface des nanotubes de carbone avait aidé à l’amélioration de la conductivité électrique et la résistance mécanique des prototypes. Le taux de cristallinité généré durant le procédé de moulage par compression des prototypes de plaques bipolaires ainsi que la cinétique de cristallisation jouent un rôle important pour l’optimisation des propriétés électriques et mécaniques visées.