α′ phase stability in Nd-Li-sialon systems

The formability and stability of the alpha-sialon (alpha') phase was investigated in multi-cation Nd-Li-sialon systems. Four samples were prepared, ranging from a pure Nd-sialon to a pure Li-sialon, with two intermediate samples being prepared with either lithium or neodymium replacing the other alpha'-stabilising additive by 20 eq.%, as to maintain an equivalent design composition in all samples. After sintering, all samples were subsequently heat treated up to 192 h at 1450 and 1300 degreesC. While significant quantities of the beta'-sialon (beta' phase were found in most samples, the high-lithium Li-Nd-sialon sample was found to be almost pure a' phase after sintering. Furthermore, the long-term stability of the a' phase on heat treatment was also found to be superior in both multi-cation samples than in either of the single-alpha'-stabilising-cation samples. This is thought to be related to improved retention of the lithium in the multi-cation systems, as much of the lithium was found to volatilise during sintering in the neodymium-free sample. (C) 2002 Elsevier Science Ltd. All rights reserved.

Effect of mesoporosity of vanadium oxide prepared by sol-gel process as cathodic material evaluated by cyclability during Li(+) insertion/deinsertion

The effect of pore structure on the behavior of lithium intercalation into an electrode containing porous V(2)O(5) film has been investigated and compared with the electrode containing a non-porous V(2)O(5) film. X-ray diffraction patterns indicate a lamellar structure for both materials. Nitrogen adsorption isotherms, t-plot method, and Scanning Electronic Microscopy show that the route employed for the preparation of mesoporous V(2)O(5) was successful. The electrochemical performance of these matrices as lithium intercalation cathode materials was evaluated. The porous material reaches stability after several cycles more easily compared with the V(2)O(5) xerogel. Lithium intercalation into the porous V(2)O(5) film electrode is crucially influenced by pore surface and film surface irregularity, in contrast with the non-porous surface of the V(2)O(5) xerogel.

Synthesis of naturally occurring diene and trienes by Te/Li exchange on (1Z,3Z)-butyltelluro-4-methoxy-1,3-butadiene

(1Z,3Z)-Butyltelluro-o-4-methoxy-1,3-butadiene 2 was obtained by the hydrotelluration of(Z)-1-methoxy-but-1-en-3-ynes 1. The butadienyllithium 3 obtained by the Te/Li exchange reaction in the (1Z,3Z)-1-butyltelluro-4-methoxy-1.3-butadiene 2 reacted with aldehydes to form the corresponding alcohols 4a-d with total retention of configuration. The alcohols formed undergo hydrolysis, resulting in the alpha,beta,gamma,delta-unsaturated aldehydes of (E,E) configuration, which are precursors of trienes obtained from natural sources. The products of this reaction were employed in the synthesis of methyl-(2E,4E)-decadienoate 7, which is a component of the flavor principles of ripe Bartlett pears. Performing the Wittig reaction of the methyl triphenylphosphorane with the deca-(2E,4E)-dienal 5a, we were able to synthesize the undeca-(1,3E,5E)-triene 6a. This compound is a sex-pheromone component of the marine brown algae Fucus serratus, Dictyopteris plagiograma, and Dictyopteris australis. Performing the Wittig reaction of methyl triphenylphosphorane with the octa-(2E,4E)-dienal 5c, the nona-(1,3E,5E)-triene 6b was synthesized. The compound obtained is a sex-pheromone component of the marine brown alga Sargassum horneri. The octa-( 1,3E,5E)-triene 6c was easily obtained from hepta-(2E,4E)-dienal 5d by the Wittig reaction with methyl triphenylphophorane. This compound is a sex-pheromone component of the marine brown alga Fucus serratus. (C) 2010 Elsevier Ltd. All rights reserved.

Bovine embryo transfer recipient synchronisation and management in tropical environments

Numerous studies have shown that it is possible to manipulate follicular and luteal dynamics, thereby eliminating the need for oestrus detection in embryo transfer (ET) programmes. Fixed-time ET (FTET) protocols are based on the use of gonadotrophin-releasing hormone (GnRH) and prostaglandin (PG) F or progesterone/progestogen (P4)-releasing devices and oestradiol. The FTET protocols increases the proportion of recipients transferred, and therefore pregnancy rates, compared with the use of PGF followed by ET 7 days after oestrus. Furthermore, the addition of equine chorionic gonadotrophin (eCG) to the P4 and oestradiol-based FTET protocols results in an even higher proportion of recipients transferred, and thus higher pregnancy rates. The beneficial effect of eCG treatment may be related to increased growth of the dominant follicle and increased plasma P4 concentrations during the subsequent luteal phase. In Bos taurus x Bos indicus recipients, pregnancy rates were positively correlated with the diameter of the corpus luteum (CL) and the number of CL at ET. When repeat-breeder Holstein cows were used as recipients, FTET protocols increased number of recipients transferred and pregnancy rates compared with the traditional PGF-based synchronisation protocols. In conclusion, the use of FTET protocols eliminates the need for the detection of oestrus and results in a greater proportion of recipients transferred and satisfactory pregnancy rates. Thus, FTET optimises the use of recipients, reducing labour and animal handling and facilitating the use of ET.

Texto para discuss??o 12: a moderniza????o do Estado: as li????es de uma experi??ncia

Falar da moderniza????o do Estado n??o ?? f??cil atualmente, t??o numerosos s??o os excelentes especialistas que, ao longo dos ??ltimos anos, dedicaram-se a este tema e produziram relat??rios n??o menos excelentes. Com efeito, se h?? um campo que tem sido regularmente classificado como uma prioridade governamental ?? exatamente este.

Ger??ncia de recursos humanos no setor p??blico: li????es da reforma em pa??ses desenvolvidos

Texto que analisa aspectos diversos relativos aos Recursos Humanos do Servi??o P??blico nos pa??ses industrializados, visando contribuir para a solu????o dos dilemas enfrentados pelos pa??ses em desenvolvimento nos seus atuais processos de reforma do Estado.

Do her??ico ao cotidiano: li????es aprendidas na condu????o de projetos horizontais

Este Caderno traz o relat??rio elaborado pela Mesa-Redonda de Pesquisa A????o sobre a Gest??o de Iniciativas Horizontais, do Centro Canadense para o Desenvolvimentoda Gest??o do Canad??, que objetiva avaliar iniciativas e pesquisas realizadas,identificar li????es e oferecer orienta????es pr??ticas a gerentes sobre efic??ciaem gest??o horizontal

Planejamento estrat??gico governamental em contexto democr??tico: li????es da Am??rica Latina

Livro sobre Planejamento Estrat??gico, decorrente de curso do mesmo nome, realizado na ENAP em 2013, em parceria com o Centro Latino Americano de Administra????o para o Desenvolvimento (CLAD)

O modelo organiza????es sociais: li????es e oportunidades de melhoria

As Organiza????es Sociais (OS) s??o organiza????es sem fins lucrativos, ???qualificadas??? para absorver atividades executadas por organiza????es p??blicas, nos termos e condi????es estabelecidas em contratos de gest??o firmados entre organiza????es e o governo. Este artigo relata os principais resultados do semin??rio ???O modelo OS: li????es e oportunidades de melhorias???, realizado em outubro de 2001, do qual participaram gestores e t??cnicos da Secretaria de Gest??o (SEGES), de OS, de ??rg??os supervisores dessas organiza????es, de ??rg??os intervenientes, e especialistas em gest??o p??blica. Com rela????o ??s OS analisadas, pode-se perceber que: a) h?? controv??rsias e ambig??idades quanto ?? sua natureza jur??dica e quanto ao processo de avalia????o dessas organiza????es; b) a gest??o de recursos humanos ?? afetada pela exist??ncia de grupos submetidos a distintos regimes de trabalho, isto ??, Estatuto dos Funcion??rios P??blicos e Consolida????o das Leis do Trabalho; c) a gest??o de recursos financeiros ?? marcada pela irregularidade no fluxo dos referidos recursos; e d) o controle dos bens p??blicos ocorre de forma fr??gil e o processo de compra est?? sendo realizado sem problemas. Com base nessas considera????es, o documento prop??e algumas sugest??es de aperfei??oamento do modelo OS.

Adapted Gaussian basis sets for atoms from Li through Xe generated with the generator coordinate Hartree-Fock method

Utiliza-se o método coordenada geradora Hartree-Fock para gerar bases Gaussianas adaptadas para os átomos de Li (Z=3) até Xe (Z=54). Neste método, integram-se as equações de Griffin-Hill-Wheeler-Hartree-Fock através da técnica de discretização integral. Comparam-se as funções de ondas geradas neste trabalho com as funções de ondas Roothaan-Hartree-Fock de Clementi e Roetti (1974) e com outros conjuntos de bases relatados na literatura. Para os átomos estudados aqui, os erros em nossas energias totais relativos aos limites numéricos Hartree-Fock são sempre menores que 7,426 milihartree.

Effect of fiber orientation in gelled poly (vinylience fluoride) electrospun membranes for Li-ion battery applications

Battery separators based on electrospun membranes of poly(vinylidene fluoride) (PVDF) have been prepared in order to study the effect of fiber alignment on the performance and characteristics of the membrane. The prepared membranes show an average fiber diameter of ~272 nm and a degree of porosity of ~87 %. The gel polymer electrolytes are prepared by soaking the membranes in the electrolyte solution. The alignment of the fibers improves the mechanical properties for the electrospun membranes. Further, the microstructure of the membrane also plays an important role in the ionic conductivity, being higher for the random electrospun membrane due to the lower tortuosity value. Independently of the microstructure, both membranes show good electrochemical stability up to 5.0 V versus Li/Li+. These results show that electrospun membranes based on PVDF are appropriate for battery separators in lithium-ion battery applications, the random membranes showing a better overall performance.