957 resultados para Pentacianoferrato(ll)
Resumo:
Neste trabalho, foram estudadas as propriedades fotoquímica e/ou fotofísica de alguns compostos de coordenação de rênio(l) e ferro(I I). A irradiação dos complexos fac-[Re(CO)3(NN)(trans-L)]+, NN= 4,7-difenil-1,10- fenantrolina (ph2phen) ou 5-cloro-1,10-fenantrolina (Clphen) e L = 1,2-bis(4-piridil)etileno (bpe) ou 4-estirilpiridina (stpy), em acetonitrila ou em filme de poli(metacrilato de metila) (PMMA) resulta em variações espectrais condizentes com a fotoisomerização trans-cis do ligante coordenado. A determinação dos rendimentos quânticos para a fotorreação pela variação espectral resultou em valores aparentes, uma vez que o reagente e o fotoproduto absorvem na mesma região. Para a determinação do rendimento quântico real, Φreal, utilizou-se a técnica de 1H RMN, na qual os sinais do fotoproduto e do reagente são observados em regiões distintas com diferentes constantes de acoplamento. Os valores de Φreal obtidos para fac-[Re(CO)3h(NN)(trans-bpe)]+ (ph2phen: Φ313= 0,43 ± 0,03; Φ365= 0,44 ± 0,02; Φ404= 0,43 ± 0,02; Clphen: Φ313= 0,56 ± 0,03; Φ365= 0,55 ± 0,04; Φ404= 0,57 ± 0,06) são independentes do comprimento de onda de irradiação, indicando a existência de um único canal para a população do estado excitado 3ILtrans-bpe. Por outro lado, para fac-[Re(CO)3(NN)(trans-stpy)]+, os valores de Φreal sob irradiação a 404 nm são menores que os determinados para os demais comprimentos de onda de irradiação (ph2phen: Φ313= 0,60 ± 0,05; Φ365= 0,64 ± 0,09; Φ404= 0,42 ± 0,03; Clphen: Φ313= 0,52 ± 0,05; Φ365= 0,58 ± 0,02; Φ404= 0,41 ± 0,06), indicando que, a energias maiores, em que o Iigante absorve significativamente, deve existir a contribuição de outro canal para a população do estado excitado 3ILtrans-stpy. A eficiência do fotoprocesso foi avaliada por meio da substituição dos ligantes NN e/ou L, e a diferença nos valores de Φreal entre os complexos deve estar relacionada principalmente com as distintas eficiências de cruzamento intersistemas. o fotoprocesso altera as propriedades fotofísicas desses complexos. Os isômeros trans apresentam fraca ou nenhuma emissão a 298 K, enquanto os fotoprodutos, fac-[Re(CO)3(NN)(cis-L)]+, apresentam intensa luminescência dominada pelo estado excitado 3MLCTRe→NN, que é sensivel à rigidez do meio. A reatividade fotoquímica dos pentacianoferratos(II) [Fe(CN)5 (NN)]3-, NN= 2aminobenzilamina (aba), 2-aminobenzamida (ab), 2-(dimetilaminometil)-3-hidroxipiridina (dmampy), 2-aminometilpiridina (ampy), 2-aminoetilpiridina (aepy) ou 2-(2metilaminoetil) piridina (maepy), também foi investigada. A irradiação desses complexos resulta na fotossubstituição do CN-, a qual só pode ser detectada quando o ligante possui um segundo grupo coordenante nas proximidades da esfera de coordenação. Os rendimentos quânticos da fotossubstituição são dependentes do comprimento de onda de irradiação (Φ313= 0,13 ± 0,01; Φ334= 0,091 ± 0,001; Φ365= 0,056 ± 0,002; Φ404= 0,022 ± 0,002; Φ436= 0,015 ± 0,001, por exemplo, para NN = aba) e indicam a existência de canais distintos pelos quais a fotorreação ocorre ou as diferentes eficiências de cruzamento intersistema para a população do estado excitado reativo. A eficiência do fotoprocesso também depende do Iigante utilizado (λirr= 365 nm: Φaba= 0,056, Φab= 0,14, Φampy= 0,046, Φaepy= 0,066, Φmaepy= 0,069 e Φdmampy= 0,12). Na série das diaminas, o rendimento quântico é maior para [Fe(CN)5(ab)]3-, que possui dois sítios para ocorrer o fechamento do anel. Na série das aminopiridinas, observa-se a influência do comprimento da cadeia na eficiência do fechamento do anel. A presença de metilas ligadas ao nitrogênio alifático deve ter pouca ou nenhuma influência na eficiência do fotoprocesso.
Resumo:
The recent release of the Gonski Review recognises the decline in Australia’s schooling performances over the last decade, noting in particular a distressing increase in the ‘achievement gap’ affecting students from low SES backgrounds (Gonski, 2012). The report details the need for more quality in teachers throughout the schooling system, particularly within the schools with the greatest academic needs. This paper specifically focuses on a group of high-achieving pre-service English teachers. In their last two years of university study, they participated in a program called Exceptional Teachers for Disadvantaged Schools (ETDS), designed to prepare them to work in disadvantaged or low SES schools. We wanted to capture their experiences of teaching in challenging settings during their practicum, and as they prepared to graduate, we wondered what they now felt about teaching English in low SES schools. Using narrative inquiry, we analysed a range of reflective data to gain insight into such things as their initial motivations for entering the teaching profession and how their preconceived expectations may or may not have shifted after practicum experiences in low SES schools. We encouraged open reflection about how they perceived themselves as English teachers.
Resumo:
Lending teachers for two-year periods is one of the ways in which Cuba has been able to collaborate with other countries in their efforts to improve educational planning and practice. My field research in 2001 in Jamaica (March and November) and in Namibia (December) enabled me to obtain information about how Cuban teachers are being utilized, and about the educational implications of this project. In Jamaica, I interviewed 15 Cuban teachers in several schools and one in the vocational institute, as well as the Cuban project supervisor in charge of the 51 Cuban teachers. I also talked with officials at the Jamaican Ministry of Education to obtain an idea of the developmental needs in the various subjects that the Cubans had been asked to teach. In Namibia I interviewed personnel in the National Sports Directorate and the Cuban manager in charge of the sports education project. The chapter draws on these interviews to build a picture of how the program of collaboration is organized, and considers its postcolonial significance, in theory and in practice, as an example of South-South collaboration. The chapter contributes to a multilevel style of comparative education analysis based on microlevel qualitative fieldwork within a framework that compares cross-cultural issues and national policies. The discussion of the educational situation of the host countries suggests why Cuban teachers can contribute to meeting curricular needs, particularly in the areas of the sciences, mathematics, Spanish, and sports. The friendly and joking remark of one of the Cuban teachers to school students in Jamaica: “You help me improve my English, I’ll teach you Physics!” highlights the reciprocal potential of these cooperation projects, discussed in several chapters of this book.
Resumo:
Purpose Young novice drivers are at considerable risk of injury on the road, and their behaviour appears vulnerable to the social influence of their friends. Research was undertaken to identify the nature and mechanisms of peer influence upon novice driver (16-25 years) behaviour to inform the design of more effective young driver countermeasures. Methods. Peer influence was explored in small group interviews (n = 21) and three surveys (n1 = 761, n2 = 1170, n3 = 390) as part of a larger Queensland-wide study. Surveys two and three were part of a six-month longitudinal study. Results Peer influence was reported from the pre-Licence to the Provisional (intermediate) periods. Young novice drivers who experienced or expected social punishments including ‘being told off’ for risky driving reported less riskiness. Conversely young novice drivers who experienced or expected social rewards such as being ‘cheered on’ by their friends – who were also more risky drivers – reported more risky driving including crashes and offences. Conclusions Peers appear influential in the risky behaviour of young novice drivers, and influence occurs through social mechanisms of reinforcement and sanction. Interventions enhancing positive influence and curtailing negative influence may improve road safety outcomes not only for young novice drivers, but for all persons who share the road with them. Among the interventions warranting further development and evaluation are programs to encourage the modelling of safe driving behaviour and attitudes by young drivers; and minimisation of social reinforcement and promotion of social sanctions for risky driving behaviour in particular.
Resumo:
SIC and DRS are related proteins present in only four of the more than 200 Streptococcus pyogenes emm-types. These proteins inhibit complement mediated lysis and/or the activity of certain antimicrobial peptides. A gene encoding a homologue of these proteins, herein called DrsG, has been identified in the related bacterium Streptococcus dysgalactiae subsp equisimilis (SDSE). Here we show that geographically dispersed isolates representing 14 of 50 emm-types examined possess variants of drsG. However not all isolates within the drsG-positive emm-types possess the gene. Sequence comparisons also reveal a high degree of conservation in different SDSE emm-types. To examine the biological activity of DrsG, recombinant versions of two major DrsG variants, DrsGS and DrsGL, were expressed and purified. Western blot analysis using antisera raised to these proteins demonstrated both variants to be expressed and secreted into culture supernatant. Unlike SIC, but similar to DRS, DrsG does not inhibit complement mediated lysis. However, like both SIC and DRS, DrsG is a ligand of the cathelcidin LL-37 and is inhibitory to its bactericidal activity in in vitro assays. The greatest similarity between DrsG and DRS/SIC is found in the signal sequence at the amino terminus and proline rich domains in the C-terminal half of the protein. Conservation of prolines in this latter region also suggests these residues are important in the biology of this family of proteins. This is the first report demonstrating the activity of an AMP inhibitory protein in SDSE. These results also suggest that inhibition of AMP activity is the primary function of this family of proteins. The acquisition of complement inhibitory activity of SIC may reflect its continuing evolution.
Resumo:
Occupational segregation is a major source of labour market rigidity and economic inefficiency due to a waste of human resources. Organisations are repeatedly recognised as gendered constructs exhibiting sustained work segregation, income and status inequality, as well as cultural and individual images of gender, and these are perpetuated through their processes, practices and pressures (Acker, 1990). A large percentage of Australia’s workforce is now employed in project-based or project-oriented organisations, leading to the claim that Australia is a project-based economy. For a continued strong performance in this economy, organisations that employ project personnel will need to consider how they address inclusivity and equality in diversity in project based temporary organisations to ensure the supply of high quality project professionals into the future. This paper investigates the inclusion processes experienced and exercised by men and women working in temporary organisations in project situations through a review of reports on the inclusion processes experienced by 60 project managers and project workers in three project based industries in Australia. Results indicate that temporary organisations are not implementing equality and diversity management strategies at the macro level and project workers are accepting this lack of recognition. However inclusivity and equality at the micro level of the team is seen as vital.
Resumo:
This article is based on Final Report: The Effects of Plant Closing or Threat of Plant Closing on the Right of Workers to Organize. The report was commissioned by the tri-national Labor Secretariat of the Commission for Labor Cooperation (the NAFTA labor commission) "on the effects of the sudden closing of the plant on the principle of freedom of association and the right of workers to organize in the three countries."
Resumo:
The conformation of three linked peptide units having an internal 4 → 1 type of hydrogen bond has been studied in detail, and the low energy conformations are listed. These conformations all lead to the reversal of the chain direction, and may therefore be called as “hairpin bends” or “U-bends”. Since this bend can occur at the end of two chains hydrogen-bonded in the antiparallel β-conformation, it is also known as the “β-bend”. Two types of conformation are possible when the residues at the second and third Cα atoms are both of type L (the LL bend), while only one type is possible for the LD and the DL bend. The LL bend can also accommodate the sequences LG, GL, GG (G = glycine), while the LD bend can accommodate the sequences LG, GD and GG. The conformations for the sequences DD and DL are exact inverses (or mirror images) of those for the sequences LL and LD, respectively, and have dihedral angles (phi2, ψ2), (phi3, ψ3) of the same magnitudes, but of opposite signs as those for the former types, which are listed, along with the characteristics (length, angle and energy) of the hydrogen bonds. A comparison of the theoretical predictions with experimental data (from X-ray diffraction and NMR studies) on proteins and peptides, show reasonably good agreement. However, a systematic trend is observable in the experimental data, slightly deviating from theory, which indicates that some deformations occur in the shapes of the peptide units forming the bend, differing from that of the standard planar peptide unit.
Resumo:
We present a search for exclusive Z boson production in proton-antiproton collisions at sqrt(s) = 1.96 TeV, using the CDF II detector at Fermilab. We observe no exclusive Z->ll candidates and place the first upper limit on the exclusive Z cross section in hadron collisions, sigma(exclu) gammagamma->p+ll+pbar, and measure the cross section for M(ll) > 40 GeV/c2 and |eta(l)|
Resumo:
We report a measurement of the ratio of the tt̅ to Z/γ* production cross sections in √s=1.96 TeV pp̅ collisions using data corresponding to an integrated luminosity of up to 4.6 fb-1, collected by the CDF II detector. The tt̅ cross section ratio is measured using two complementary methods, a b-jet tagging measurement and a topological approach. By multiplying the ratios by the well-known theoretical Z/γ*→ll cross section predicted by the standard model, the extracted tt̅ cross sections are effectively insensitive to the uncertainty on luminosity. A best linear unbiased estimate is used to combine both measurements with the result σtt̅ =7.70±0.52 pb, for a top-quark mass of 172.5 GeV/c2.
Resumo:
We report a measurement of the ratio of the tt̅ to Z/γ* production cross sections in √s=1.96 TeV pp̅ collisions using data corresponding to an integrated luminosity of up to 4.6 fb-1, collected by the CDF II detector. The tt̅ cross section ratio is measured using two complementary methods, a b-jet tagging measurement and a topological approach. By multiplying the ratios by the well-known theoretical Z/γ*→ll cross section predicted by the standard model, the extracted tt̅ cross sections are effectively insensitive to the uncertainty on luminosity. A best linear unbiased estimate is used to combine both measurements with the result σtt̅ =7.70±0.52 pb, for a top-quark mass of 172.5 GeV/c2.
Resumo:
We report a measurement of the ratio of the top-antitop to Z/gamma* production cross sections in sqrt(s) = 1.96 TeV proton-antiproton collisions using data corresponding to an integrated luminosity of up to 4.6 fb-1, collected by the CDF II detector. The top-antitop cross section ratio is measured using two complementary methods, a b-jet tagging measurement and a topological approach. By multiplying the ratios by the well-known theoretical Z/gamma*->ll cross section, the extracted top-antitop cross sections are effectively insensitive to the uncertainty on luminosity. A best linear unbiased estimate is used to combine both measurements with the result sigma_(top-antitop) = 7.70 +/- 0.52 pb, for a top-quark mass of 172.5 GeV/c^2.
Resumo:
A Cambridge Structural Database (CSD) analysis on halogen center dot center dot center dot halogen contacts (X...X) in organic crystals has been carried out to review the classification criteria for type I, type II, and quasi type I/II halogen interactions. Trends observed in previous CSD analyses of the phenomenon are reinforced in the present study. The manner in which these interactions are manifested in cocrystals of 4-bromobenzamide and dicarboxylic acid is examined. The design strategy for these cocrystals uses synthon theory and follows from an understanding of the crystal structures of gamma-hydroquinone and a previously studied set of 4-hydroxybenzamide dicarboxylic acid cocrystals, making use of Br/OH isostructurality. All cocrystals are obtained by clean insertion of dicarboxylic acids between 4-bromobenzamide molecules. The strategy is deliberate and the prediction of synthons done well in advance, as evidenced from the robustness of the acid-amide heterosynthons in all nine crystal structures, with no aberrant structures in the crystallization experiments. Formation of the acid-amide synthon in these cocrystals is identified with IR spectroscopy. The packing in these cocrystals can be distinguished in terms of whether the Br...Br interactions are type I or II. Eight sets of dimorphs were retrieved from the CSD, wherein the basis of the polymorphism is that one crystal has a type I Br...Br interaction, while the other has a type II interaction.
Resumo:
马铃薯蛋白酶抑制剂Ⅱ(PinⅡ)是一种丝氨酸蛋白酶抑制剂,能同时具有抑制胰凝乳蛋白酶及胰蛋白酶胰凝乳蛋白酶的作用位点,饲喂幼虫含PinⅡ的饲料及转基因植物叶子的实验显示了较强的杀虫能力。为了获得一个广谱的抗虫基因用于增强植物对虫害的抵抗力,本文用PCR程序从马铃薯基因组中克隆了Pin II的基因,并构建了以CaMV 35S启动子驱动的表达PinⅡ的双元表达载体质粒,将其转入农杆菌,通过农杆菌介导的途径转化烟草,已在卡那霉素培养基上筛选出Km抗性的植株。