Magnetic resonance and conductivity study of gelatin-based proton conductor polymer electrolytes

This work report results from proton nuclear magnetic resonance (NMR), continuous-wave (CW-EPR) and pulsed electron paramagnetic resonance (P-EPR) and complex impedance spectroscopy of gelatin-based polymer gel electrolytes containing acetic acid. cross-linked with formaldehyde and plasticized with glycerol. Ionic conductivity of 2 x 10(-5) S/cm was obtained at room temperature for samples prepared with 33 wt% of acetic acid. Proton ((1)H) line shapes and spin-lattice relaxation times were measured as a function of temperature. The NMR results show that the proton mobility is dependent on acetic acid content in the plasticized polymer gel electrolytes. The CW-EPR spectra, which were carried out in samples doped with copper perchlorate, indicate the presence of the paramagnetic Cu(2+) ions in axially distorted sites. The P-EPR technique, known as electron spin echo envelope modulation (ESEEM), was employed to show the involvement of both, hydrogen and nitrogen atoms, in the copper complexation of the gel electrolyte. (C) 2009 Elsevier Ltd. All rights reserved.

Structural Characterization of Rare-Earth Doped Yttrium Aluminoborate Laser Glasses Using Solid State NMR

The structure of laser glasses in the system (B(2)O(3))(0.6){(Al(2)O(3))(0.4-x)(Y(2)O(3))(x)} (0.1 <= x <= 0.25) has been investigated by means of (11)B, (27)Al, and (89)Y solid state NMR as well as Y-3d core-level X-ray photoelectron spectroscopy, (11)B magic-angle spinning (MAS) NMR spectra reveal that the majority of the boron atoms are three-coordinated, and a slight increase of four-coordinated boron content with increasing x can be noticed. (27)Al MAS NMR spectra show that the alumina species are present in the coordination states four, five and six. All of them are in intimate contact with both the three- and the four-coordinate boron species and vice versa, as indicated by (11)B/(27)Al rotational echo double resonance (REDOR) data. These results are consistent with the formation of a homogeneous, nonsegregated glass structure. For the first time, (89)Y solid state NMR has been used to probe the local environment of Y(3+) ions in a glass-forming system. The intrinsic sensitivity problem associated with (89)Y NMR has been overcome by combining the benefits of paramagnetic doping with those of signal accumulation via Carr-Purcell spin echo trains. Both the (89)Y chemical shifts and the Y-3d core level binding energies are found to be rather sensitive to the yttrium bonding state and reveal that the bonding properties of the yttrium atoms in these glasses are similar to those found in the model compounds YBO(3) and YAl(3)(BO(3))(4), Based on charge balance considerations as well as (11)B NMR line shape analyses, the dominant borate species are concluded to be meta- and pyroborate anions.

Preparation and structural characterization of rare-earth doped lead lanthanum zirconate titanate ceramics

A new preparation route towards rare-earth (RE) doped polycrystalline lead lanthanum zirconate titanate (PLZT) ceramics (RE = Y(3+), Nd(3+), Yb(3+)), based on the use of doped lanthanum oxide or zirconia, is reported. Structural characterization by X-ray powder diffraction reveals that secondary phase formation can be substantially diminished in comparison to conventional preparation methods. The distribution of the rare-earth dopants was investigated as a function of concentration by static (207)Pb spin echo NMR spectra, using Fourier Transformation of Carr-Purcell-Meiboom-Gill spin echo trains. For the Nd- and Yb-doped materials, the interaction of the (207)Pb nuclei with the unpaired electron spin density results in significant broadening and shifting of the NMR signal, whereas these effects are absent in the diamagnetic Y(3+) doped materials. Based on different concentration dependences of the NMR lineshape parameters, we conclude that the structural role of the Nd(3+) dopants differs significantly from that of Yb(3+). While the Nd(3+) ions appear to be statistically distributed in the PLZT lattice, incorporation of Yb(3+) into PLZT appears to be limited by the appearance of doped cubic zirconia as a secondary phase. (C) 2009 Elsevier Masson SAS. All rights reserved.

Solid state NMR as a new approach for the structural characterization of rare-earth doped lead lanthanum zirconate titanate laser ceramics

To facilitate the design of laser host materials with optimized emission properties, detailed structural information at the atomic level is essential, regarding the local bonding environment of the active ions (distribution over distinct lattice sites) and their extent of local clustering as well as their population distribution over separate micro- or nanophases. The present study explores the potential of solid state NMR spectroscopy to provide such understanding for rare-earth doped lead lanthanum zirconate titanate (PLZT) ceramics. As the NMR signals of the paramagnetic dopant species cannot be observed directly, two complementary approaches are utilized: (1) direct observation of diamagnetic mimics using Sc-45 NMR and (2) study of the paramagnetic interaction of the constituent host lattice nuclei with the rare-earth dopant, using Pb-207 NMR lineshape analysis. Sc-45 MAS NMR spectra of scandium-doped PLZT samples unambiguously reveal scandium to be six-coordinated, suggesting that this rare-earth ion substitutes in the B site. Static Pb-207 spin echo NMR spectra of a series of Tm-doped PLZT samples reveal a clear influence of paramagnetic rare-earth dopant concentration on the NMR lineshape. In the latter case high-fidelity spectra can be obtained by spin echo mapping under systematic incrementation of the excitation frequency, benefiting from the signal-to-noise enhancement afforded by spin echo train Fourier transforms. Consistent with XRD data, the Pb-207 NMR lineshape analysis suggests that statistical incorporation into the PLZT lattice occurs at dopant levels of up to 1 wt.% Tm3+, while at higher levels the solubility limit is reached. (C) 2008 Elsevier Masson SAS. All rights reserved.

Structural role of fluoride in the ion-conducting glass system B(2)O(3)-PbO-LiF studied by single- and double-resonance NMR

The local structure of an ion-conducting glass with nominal composition 50B(2)O(3)-10PbO-40LiF has been investigated by complementary (7)Li, (11)B, (19)F, and (207)Pb single- and double-resonance experiments. The results give insight into the structural role of the lithium fluoride additive in borate glasses: (1) LiF is seen to actively participate in the network transformation process contributing to the conversion of three- into four-coordinate boron units, as shown by (11)B single-resonance as well as by (11)B{(19)F} and (19)F{(11)B} double-resonance experiments. (2) (19)F signal quantification experiments suggest substantial fluoride loss, presumably caused by formation of volatile BF(3). A part of the fluoride remains in the dopant role, possibly in the form of small LiF-like cluster domains, which serve as a mobile ion supply. (3) The extent of lithium-fluorine and lead-fluorine interactions has been characterized by (7)Li{(19)F} and (207)Pb{(19)F} REDOR and SEDOR experiments. On the basis of these results, a quantitative structural description of this system has been developed.

Magnetic resonance study of a vanadium pentoxide gel

In this work we report results from continuous-wave (CW) and pulsed electron paramagnetic resonance (EPR) and proton nuclear magnetic resonance (NMR) studies of the vanadium pentoxide xerogel V2O5:nH(2)O (n approximate to 1.6). The low temperature CW-EPR spectrum shows hyperfine structure due to coupling of unpaired V4+ electron with the vanadium nucleus. The analysis of the spin Hamiltonian parameters suggests that the V4+ ions are located in tetragonally distorted octahedral sites. The transition temperature from the rigid-lattice low-temperature regime to the high temperature liquid-like regime was determined from the analysis of the temperature dependence of the hyperfine splitting and the V4+ motional correlation time. The Electron Spin Echo Envelope Modulation (ESEEM) data shows the signals resulting from the interaction of H-1 nuclei with V4+ ions. The modulation effect was observed only for field values in the center of the EPR absorption spectrum corresponding to the single crystals orientated perpendicular to the magnetic field direction. At least three protons are identified in the xerogel by our magnetic resonance experiments: (I) the OH groups in the equatorial plane, (ii) the bound water molecules in the axial V=O bond and (iii) the free mobile water molecules between the oxide layers. Proton NMR lineshapes and spin-lattice relaxation times were measured in the temperature range between 150 K and 323 K. Our analysis indicates that only a fraction of the xerogel protons contribute to the measured conductivity.

Glass-to-Vitroceramic Transition in the Yttrium Aluminoborate System: Structural Studies by Solid-State NMR

The crystallization of laser glasses in the system (B(2)O(3))(0.6){(Al(2)O(3))(0.4-y)(Y(2)O(3))(y)} (0.1 <= y <= 0.25) doped with different levels of ytterbium oxide has been investigated by X-ray powder diffraction, differential thermal analysis, and various solid-state NMR techniques. The homogeneous glasses undergo major phase segregation processes resulting in crystalline YBO(3), crystalline YAI(3)(BO(3))(4), and residual glassy B(2)O(3) as the major products. This process can be analyzed in a quantitative fashion by solid-state (11)B, (27)Al, and (89)Y NMR spectroscopies as well as (11)B{(27)Al} rotational echo double resonance (REDOR) experiments. The Yb dopants end up in both of the crystalline components, producing increased line widths of the corresponding (11)B, (27)Al, and (89)Y NMR resonances that depend linearly on the Yb/Y substitution ratio. A preliminary analysis of the composition dependence suggests that the Yb(3+) dopant is not perfectly equipartitioned between both crystalline phases, suggesting a moderate preference of Yb to substitute in the crystalline YBO(3) component.

Local Structure and Photochromic Response in Ormosils Containing Dodecatungstophosphoric Acid

Two hybrid materials based on dodecatungstophosphoric acid (HPW) dispersed in ormosils modified with 3-aminopropiltrietoxysilane (APTS) or with N-(3-(trimethoxysilyl)-propyl)-ethylene-diamine (TSPEN) show reversible photochromic response induced by irradiation in the 200-390 nm UV range. A set of solid-state nuclear magnetic resonance (NMR) techniques was used to analyze the structural properties of the main components of these hybrids (the HPW polyanion, the inorganic matrix, and the organic functionalities). For the ormosils, the use of (29)Si NMR, {(1)H}-(29)Si cross-polarization, and {(1)H}-(29)Si HETCOR revealed a homogeneous distribution of silicon species Q ``, T(2), and T(3) for the APTS hybrid, contrasting with the separation of T(3) species in the TSPEN hybrid. The combination of (31)P NMR, {(1)H}-(31)P cross-polarization and (31)P-{(1)H} spin-echo double resonance (SEDOR) revealed the dispersion of the HPW ions in the ormosil, occupying sites with a high number of close protons (>50). Differences in the molecular dynamics at room temperature, inferred from SEDOR experiments, indicate a state of restricted mobility of the HPW ion and the surrounding molecular groups in the TSPEN hybrid. This behavior is consistent with the presence of more amino groups in the TSPEN, acting as chelating groups to the HPW ion. This hybrid, with the strong chelate interaction of the diamine group, shows the most intense photochromic response, in agreement with the charge transfer models proposed to explain the photochromic effect. Electronic reflectance spectroscopy in irradiated samples revealed the presence of one-electron and two-electron reduced polyanions. The one-electron reduced species could be detected also by (31)P NMR spectroscopy immediately after UV irradiation.

Healthcare providers balancing norms and practice : challenges and opportunities in providing contraceptive counselling to young people in Uganda - a qualitative study

BACKGROUND: Pregnancies among young women force girls to compromise education, resulting in low educational attainment with subsequent poverty and vulnerability. A pronounced focus is needed on contraceptive use, pregnancy, and unsafe abortion among young women. OBJECTIVE: This study aims to explore healthcare providers' (HCPs) perceptions and practices regarding contraceptive counselling to young people. DESIGN: We conducted 27 in-depth interviews with doctors and midwives working in seven health facilities in central Uganda. Interviews were open-ended and allowed the participant to speak freely on certain topics. We used a topic guide to cover areas topics of interest focusing on post-abortion care (PAC) but also covering contraceptive counselling. Transcripts were transcribed verbatim and data were analysed using thematic analysis. RESULTS: The main theme, HCPs' ambivalence to providing contraceptive counselling to sexually active young people is based on two sub-themes describing the challenges of contraceptive counselling: A) HCPs echo the societal norms regarding sexual practice among young people, while at the same time our findings B) highlights the opportunities resulting from providers pragmatic approach to contraceptive counselling to young women. Providers expressed a self-identified lack of skill, limited resources, and inadequate support from the health system to successfully provide appropriate services to young people. They felt frustrated with the consultations, especially when meeting young women seeking PAC. CONCLUSIONS: Despite existing policies for young people's sexual and reproductive health in Uganda, HCPs are not sufficiently equipped to provide adequate contraceptive counselling to young people. Instead, HCPs are left in between the negative influence of social norms and their pragmatic approach to address the needs of young people, especially those seeking PAC. We argue that a clear policy supported by a clear strategy with practical guidelines should be implemented alongside in-service training including value clarification and attitude transformation to equip providers to be able to better cater to young people seeking sexual and reproductive health advice.

Insuring cleaner oceans: the economics of oil pollution prevention

The current system of controlling oil spills involves a complex relationship of international, federal and state law, which has not proven to be very effective. The multiple layers of regulation often leave shipowners unsure of the laws facing them. Furthemore, nations have had difficulty enforcing these legal requirements. This thesis deals with the role marine insurance can play within the existing system of legislation to provide a strong preventative influence that is simple and cost-effective to enforce. In principle, insurance has two ways of enforcing higher safety standards and limiting the risk of an accident occurring. The first is through the use of insurance premiums that are based on the level of care taken by the insured. This means that a person engaging in riskier behavior faces a higher insurance premium, because their actions increase the probability of an accident occurring. The second method, available to the insurer, is collectively known as cancellation provisions or underwriting clauses. These are clauses written into an insurance contract that invalidates the agreement when certain conditions are not met by the insured The problem has been that obtaining information about the behavior of an insured party requires monitoring and that incurs a cost to the insurer. The application of these principles proves to be a more complicated matter. The modern marine insurance industry is a complicated system of multiple contracts, through different insurers, that covers the many facets of oil transportation. Their business practices have resulted in policy packages that cross the neat bounds of individual, specific insurance coverage. This paper shows that insurance can improve safety standards in three general areas -crew training, hull and equipment construction and maintenance, and routing schemes and exclusionary zones. With crew, hull and equipment, underwriting clauses can be used to ensure that minimum standards are met by the insured. Premiums can then be structured to reflect the additional care taken by the insured above and beyond these minimum standards. Routing schemes are traffic flow systems applied to congested waterways, such as the entrance to New York harbor. Using natural obstacles or manmade dividers, ships are separated into two lanes of opposing traffic, similar to a road. Exclusionary zones are marine areas designated off limits to tanker traffic either because of a sensitive ecosystem or because local knowledge is required of the region to ensure safe navigation. Underwriting clauses can be used to nullify an insurance contract when a tanker is not in compliance with established exclusionary zones or routing schemes.

Levines and Colby Scrapbook

Includes covers and articles from the Colby alumni magazine and from the Echo, correspondence, donor lists for the Mayflower Associates, and photographs.

Excessiva atividade de remodelamento ventricular sinaliza limitada resposta terapêutica ao manejo agressivo da insuficiência cardíaca avanaçada

Introdução: Níveis de fator de necrose tumoral–alfa (TNF-α), N-peptídeo do pró-colágeno III (PIIINP) e metaloproteinase de matriz –1 (MMP-1), marcadores biológicos de remodelamento ventricular, estão elevados em pacientes com insuficiência cardíaca (IC), talvez refletindo elevadas pressões de enchimento. A correlação destes marcadores com variáveis clínicas e hemodinâmicas permanece pouco compreendida, particularmente no contexto ambulatorial da IC. Objetivo: Avaliar níveis séricos de marcadores biológicos de remodelamento ventricular em pacientes com IC, comparando tratamento guiado por ecocardiografia (ECO), buscando redução de pressões de enchimento, versus tratamento convencional (CLÍNICO), baseado em sinais e sintomas. Métodos: Ensaio clínico randomizado. Pacientes estáveis com IC e fração de ejeção menor do que 40% foram alocados entre os grupos de tratamento e submetidos a ecocardiograma e coletas de sangue no início do estudo e em 180 dias. TNF-α e MMP- 1 foram medidos por ELISA, e PIIINP, por radioimunoensaio. Resultados: Incluiu-se 80 pacientes, com 59 ± 15 anos e fração de ejeção de 26 ± 7%; 25% isquêmicos e 52% masculinos. Houve redução dos marcadores biológicos intragrupos, não havendo diferença entre os tratamentos. No grupo CLÍNICO, os níveis de TNF-α, MMP-1 e PIIINP apresentaram diferenças estatisticamente significativas entre os momentos basal e final (respectivamente, 3,11 ± 2,90 versus 1,24 ± 0,60 pg/mL p < 0,0003; 2,66 ± 1,00 versus 1,16 ± 0,40 ng/mL p < 0,0001; 6,12 ± 2,60 versus 3,89 ± 1,60 μg/L p < 0,0001). De maneira semelhante, tal diferença também foi observada no grupo ECO para os três marcadores (respectivamente, 3,90 ± 4,90 versus 1,40 ± 1,30 pg/mL p < 0,0001; 2,50 ± 0,90 versus 1,09 ± 0,40 ng/mL p < 0,0001; 6,09 ± 2,60 versus 3,50 ± 1,30 μg/L p<0,0001). Ao final da intervenção, no entanto, não foi observada diferença significativa dos valores de TNF-α , MMP-1 e PIIINP entre os dois grupos de tratamento (p = 0,7; p = 0,8; e p = 0,2; respectivamente). A combinação dos valores basais das variáveis biológicas gerou um escore que se associou significativamente com o comportamento final das pressões atrial direita e sistólica da artéria pulmonar. Pacientes com marcadores biológicos basais no quartil 75% mantiveram níveis superiores de pressões atrial direita (13 mmHg; p = 0,034) e sistólica de artéria pulmonar (60 mmHg; p = 0,007) ao final do seguimento. Conclusão: Independente do tratamento alocado, houve redução dos níveis de marcadores biológicos ao final do seguimento; no entanto, níveis basais mais elevados destes marcadores foram preditores de menor redução das pressões em átrio direito e sistólica da artéria pulmonar. Os dados sugerem que indicativos de intenso processo de remodelamento ventricular se associam à progressão da IC e a pressões de enchimento elevadas.

Trabalho móvel: em trânsito por aeroportos e aviões

Argumenta-se na contemporaneidade que o trabalho adquiriu a possibilidade de ser realizado “a qualquer hora e em qualquer lugar” e que, particularmente, pode ser realizado em movimento, enquanto a pessoa que trabalha desloca-se de um lugar a outro. Este estudo investiga esse último, o trabalho móvel; em especial, aquele que envolve o uso de tecnologias de informação e comunicação e realizado enquanto a pessoa que trabalha desloca-se por meio do sistema de transporte aéreo. Este projeto explora, especificamente, o desempenho de espaço-tempos de trabalho em terminais de aeroportos e em aviões. Para tanto, adota a abordagem teórico-metodológica Teoria Ator-Rede que considera o social um movimento de associações entre elementos heterogêneos e os espaço-tempos, incluindo aqueles de trabalho, efeitos de modos como humanos e não humanos relacionam-se entre si. A estratégia metodológica envolveu uma combinação de observação de campo, auto-observação e entrevistas com pessoas que vivem a experiência do trabalho móvel. A coleta de dados compreendeu: (a) horas de observação de pessoas e situações, em alguns terminais de aeroportos no Brasil e em voos entre a cidade de São Paulo e outras capitais do país, e (b) entrevistas semiestruturadas com pessoas que, com certa frequência, deslocam-se para trabalhar por meio do sistema de transporte aéreo. Como resultado, este estudo contribui para as análises sobre o fenômeno do trabalho móvel, realizado em aeroportos e aviões, e destaca: os atores envolvidos, bem como os agentes que levam esses atores a agir; a quantidade de objetos ativos na manifestação do fenômeno; e as controvérsias envolvidas com o tema. Além disso, aponta elementos empíricos (i) que revelam lugares em que os fenômenos de trabalho móvel se manifestam esporadicamente, de modo disperso, como “bolhas”, e (ii) que se contrapõem à ideia que é possível trabalhar “a qualquer hora e em qualquer lugar”. As contribuições deste estudo ecoam resultados de pesquisas desenvolvidas sobre trabalho móvel, assim como apresentam particularidades, como a metáfora da bolha, amplificações de aspectos pouco presentes nos textos sobre o tema e elementos peculiares do trabalho móvel investigado no espaço-tempo da pesquisa

A partir da mulher no trabalho : um estudo de caso sobre a ascenção funcional

A análise da condição feminina é polêmica, sobremaneira, quando a trilha a ser seguida se lnsere no veio organizacional,c~ minho ainda virgem na literatura corrente. o que se tenta em termos amplos é indagar,até que ponto, as organizações negligenciam, ou ainda, reforçam,no interior de las a situação de inferioridade da mulher no plano social e familiar, seja através da cultura organizacional,com valores tradici~ nalmente "patriarcais",ou através de normas, procedimentos e ou tros instrumentos de controle da conduta funcional. o foco do estudo recairá numa Autarquia Federal (AF) , possuidora de especificidades próprias que~asseguram por um la do, no que concerne às políticas de pessoal,o ingresso e a perm~ nência de mulheres e, por outro, a reprodução das condições malS gerais de opressao de sexo ,d e uma sociedade tradicional como a brasileira. o que se tenta especificamente conhecer, é como as fun cionárias e funcionários da AF se inserem no processo de ascen são funcional, doravante chamado de o caminho para o "sucesso";se há diferenças substanciais na maneira de perceber o trabalho em si e na sua intercessão com outras esferas da vida, como família, lazer, cultura, saúde e consumo, ou na maneira de perceber o "sucesso", os requisitos e as disponibilidades para se chegar até ele. Procurar-se-á,então, levantar os possíveis pontos de estrangulamento da carreira da mulher na organização. Acredita-se que, nao obstante os condicionantes supeE. estruturais e micro-institucionais que obstaculizam a ascensao funcional feminina, sua postura em relação ao trabalho e ao "sucesso" encontrará eco em fatores outros,advindos precipuamente de sua posição na hierarquia, por hipótese.

Os contos de fadas: suas origens histórico-culturais e implicações psicopedagógicas para crianças em idade pré-escolar

Esta dissertação tem como objetivo principal elucidar as implicações de se relatar contos de fadas às crianças em idade pré-escolar, destacando-se suas origens histórico- culturais e a sua função psicopedagógica. Com subsidios obtidos em obras de alguns autores da área de história, literatura, filosofia, psicologia e pedagogia, foi feita uma análise considerando-se alguns tópicos, dentre os quais a possibilidade de serem os contos mitos transformados, cuja evolução ou construção da narrativa tem uma característica análoga aos ritos iniciáticos das sociedades consideradas "primitivas" ou pré-letradas. Neste sentido, trazem em seu bojo a nossa herança cultural. Além disso, possuem função psicopedagógica, que possibilita à criança em idade pré-escolar identificar-se com a imagem arquetípica do herói ou heroina, na medida em que estes passam por provações, e adotar uma postura positiva frente às mesmas. Argumentou-se, ainda, quanto às criticas de que estas narrativas têm sido alvo, como, por exemplo, a sua "crueldade", a visão de mundo "deturpada e irreal" que elas promoveriam de acordo com alguns autores que privilegiam o racionalismo, e o papel "degradante e passivo" destinado a algumas personagens femininas de algumas histórias. Conclui-se o trabalho avaliando-se o papel doscontos de fadas no contexto pré-escolar, e de que forma a experiência de relatá-los às crianças pode ser enriquecedora do ponto de vista pedagógico. Apoiando-se na abordagem junguiana, trata-se de um trabalho de pesquisa e análise teórica que visa ampliar, esclarecer, bem como justificar o papel dos contos de fadas na educação pré-escolar, levando-se em conta suas funções psicopedagógicas e o seu caráter socializante, na medida em que a criança tem acesso a valores sócio-culturais que predominaram e ainda repercutem nas relações sociais contemporâneas.