ZnO nanorods prepared via ablation of Zn with millisecond laser in liquid media

ZnO nanomaterials with controlled size, shape and surface chemistry are required for applications in diverse areas, such as optoelectronics, photocatalysis, biomedicine and so on. Here, we report on ZnO nanostructures with rod-like and spherical shapes prepared via laser ablation in liquid using a laser with millisecond-long pulses. By changing laser parameters (such as pulse width and peak power), the size or aspect ratio of such nanostructures could be tuned. The surface chemistry and defects of the products were also strongly affected by applied laser conditions. The preparation of different structures is explained by the intense heating of liquid media caused by millisecond-long pulses and secondary irradiation of already-formed nanostructures.

Dissociative adsorption of methane on the Cu and Zn doped (111) surface of CeO2

The development of economical heterogeneous catalysts for the activation of methane is a major challenge for the chemical industry. Screening potential candidates becomes more feasible using rational catalyst design to understand the activity of potential catalysts for CH4 activation. The focus of the present paper is the use of density functional theory to examine and elucidate the properties of doped CeO2. We dope with Cu and Zn transition metals having variable oxidation state (Cu), and a single oxidation state (Zn), and study the activation of methane. Zn is a divalent dopant and Cu can have a +1 or +2 oxidation state. Both Cu and Zn dopants have an oxidation state of +2 after incorporation into the CeO2 (111) surface; however a Hubbard +U correction (+U = 7) on the Cu 3d states is required to maintain this oxidation state when the surface interacts with adsorbed species. Dissociation of methane is found to occur locally at the dopant cations, and is thermodynamically and kinetically more favorable on Zn-doped CeO2 than Cu-doped CeO2. The origins of this lie with the Zn(II) dopant moving towards a square pyramidal geometry in the sub surface layer which facilitates the formation of two-coordinated surface oxygen atoms, that are more beneficial for methane activation on a reducible oxide surface. These findings can aid in rational experimental catalyst design for further exploration in methane activation processes.

Spéciation et biodisponibilité de métaux traces (Cd, Cu, Ni, Pb, Zn) dans la rhizosphère de sols contaminés

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Zn/Sr record of the Last Interglacial Transition in South Atlantic Ocean sediments

We examined the zinc content of diatom frustules as an indicator of past changes in surface seawater Zn2+ concentration. Zn/Si data of samples from three cores located in the South Atlantic sector of the Southern Ocean spanning the last interglacial-glacial transition are presented. Changes in the Zn/Si record are linked to changes in the surface water Zn2+ concentration. The source of variation in Zn2+ concentration appears to be via changes in deep water upwelling and circulation. We rule out changes in phytoplankton productivity and aeolian dust input as a source of variation in the Zn/Si record. Likewise, the Zn/Si data are not linked to shifts in the diatom species composition of the sediment or sediment preservation effects. The Zn/Si results presented do not support the zinc hypothesis. There is no link between the uptake of CO2 by phytoplankton, as inferred from the d13C record, and the Zn/Si record.

(Table 3, Page 417) Table 3. The concentrations of Zn, Cu, Pb, Cd, Ni, Co, Ag, Mn and Fe in a soluble in 1M HCl fraction of ferromanganese nodules of Slupsk Furrow in the southern Baltic sea

The concentration of Zn, Cu, Pb, Cd, Ni, Co, Ag, Mn, Fe, Ca, Mg, K and Na in molluscs Macoma balthica, Mya arenaria, Cardium glaucum, Mytilus edulis and Astarte borealis from the southern Baltic was determined. The surface sediments and ferromanganese concretions associated with the molluscs were also analysed for concentration of these metals. Species- and region-dependent differences in the metal levels of the organisms were observed. The properties of molluscs analysed which have a tendency toward elevated biological tolerance of selected trace metals were specified. The interelement relationship between metal concentrations in the soft tissue and the shell was estimated and was discussed.

Energy levels and radiative rates for Cr-like Cu VI and Zn VII

Energy levels and radiative rates (. A-values) for transitions in Cr-like Cu VI and Zn VII are reported. These data are determined in the quasi-relativistic approach (QR), by employing a very large configuration interaction (CI) expansion which is highly important for these ions. No radiative rates are available in the literature to compare with our results, but our calculated energies are in close agreement with those compiled by NIST and other available theoretical data, for a majority of the levels. The A-values (and resultant lifetimes) are listed for all significantly contributing E1, E2 and M1 radiative transitions among the energetically lowest 322 levels of each ion.

A Casa na Mala do Carro: flexibilidade e mobilidade geográfica como condição de trabalho da equipa de divulgação do Dia da Defesa Nacional

A flexibilidade é o conceito mais apropriado para descrever as práticas de gestão das organizações num contexto extremamente incerto e cambiante como o atual; emerge como um conceito heterogéneo, frequentemente, associado às noções de polivalência, disponibilidade, adaptabilidade, insegurança, mobilidade e instabilidade profissional. Robert Boyer (1986) foi quem denunciou, logo na década de 1980, o lado precário da flexibilidade, falando em “flexibilidade danosa”. Charles Tilly (1976) avançou o conceito de career migration, indagando o facto de os trabalhadores poderem ser deslocados de locais de trabalho para servirem os interesses da organização, subordinando-lhe os seus interesses privados. Este estudo analisou uma equipa de trabalho que está vinculada à organização militar através de um contrato por tempo determinado e que se encontra em constantes deslocações (mobilidade geográfica) no desempenho das suas funções. Trata-se da equipa do Projeto do Dia da Defesa Nacional (PDDN), constituída por 42 oficiais. Tendo em conta esta realidade, perspetivou-se conhecer a especificidade das condições de trabalho deste grupo de profissionais, problematizando especificamente as consequências positivas e negativas deste tipo de funções e a maneira como avaliam a sua situação, procurando conhecer os impactos desta forma de flexibilidade laboral. Questionou-se, em particular, os impactos da mobilidade geográfica permanente a nível da conciliação entre as várias esferas de vida, das estratégias de adaptação a cada equipa, a cada centro, às diferentes realidades militares, às diferentes cidades; questionaram-se os impactos do tipo de vínculo em termos de expetativas e estratégias profissionais, de acesso a formação e outros mecanismos de desenvolvimento profissional, do sentimento de pertença à organização, do ambiente de trabalho e das relações interpessoais, do apoio prestado pela supervisão; e também se procurou compreender as diferenças entre estes oficiais (contratados) e o pessoal do quadro permanente (QP) das Forças Armadas. Através de um inquérito por questionário e da realização de 9 entrevistas em profundidade foi possível conhecer a forma como refletem e avaliam as suas condições de trabalho, os efeitos da precariedade do seu vínculo quer na própria organização militar quer em termos de expetativas e projetos socioprofissionais, explorando-se os impactos da mobilidade geográfica permanente (mensal) nas várias esferas de vida das pessoas da equipa. / Flexibility is the concept most appropriated to describe the management practices in a highly uncertain and changing context like the present; it appears as a heterogeneous concept often associated with concepts of versatility, availability, adaptability, insecurity, professional mobility and instability. Robert Boyer (1986) denounced, then in the 1980s, the poor side of flexibility, talking of "harmful flexibility." Charles Tilly (1976) advanced the concept of “career migration”, questioning the fact that workers can be displaced from the workplace to serve the organization's interests, subordinating their own private interests. This work studied a working team that is tied to the military organization through a fixed-term contract and is in constant movement (geographical mobility) in the performance of their duties. That’s the team of Projeto do Dia da Defesa Nacional (PDDN) consisting of 42 officers. Given this reality, it sought to know the specific working conditions of this group of professionals, specifically questioning the positive and negative consequences of this kind of functions and the way they evaluate their situation, trying to understand the impacts of this form of labor flexibility. It was questioned, in particular, the impact of geographical mobility at the level of permanent reconciliation between the various spheres of life, adaptation strategies, to different cities teams, centers and military realities; questioned the impacts in terms of expectations and professional strategies, access to training and other forms of professional development, the sense of belonging to the organization, the work environment and interpersonal relationships, the support provided by supervision; and also it sought to understand the differences between these officers (hired) and the staff of the permanent (QP) of the Armed Forces. Through a survey and nine in-depth interviews we were able to understand how professionals reflect and evaluate their working conditions, the effects of the precarity either in military organization and also in terms of their expectations and socioprofessional projects, exploring the impacts of geographical mobility (monthly) in the different spheres of life.

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.