Morphology and stability of Au nanoclusters in HOPG nanopits of well-defined depth

Gold nanoparticles with a diameter comprised between 4 and 6 nm are stabilized in nanosized pits of well defined depth in highly oriented pyrolytic graphite (HOPG). These pits are produced by creation of artificial defects, followed by etching under a controlled oxygen atmosphere. At low Au coverage, clusters are found on the edges of the hexagonal pits maximizing the contact to dangling bonds on graphite multisteps. Larger coverage results in Au beads of surprisingly well defined shape and with a constant bead density per unit length. Most remarkable is the stability of these nanostructures under ambient conditions. Temperatures as high as 650K do not alter the morphology of the gold clusters. Higher temperatures do not lead to a change of the cluster morphology but to catalytically driven etching of the HOPG substrat

Ultrastructural Study of Bone Formation on Synthetic Hydroxyapatite in Osteoblast Cultures

Collagenase isolated rat calvaria cells forming a mineralized matrix in vitro were cultured in the presence of synthetic hydroxyapatite. Interactions between bone cells and hydroxyapatite biomaterial were followed by transmission electron microscopy. The appearance of a granular, collagen free, electron-dense layer at the periphery of the material was noted initially. Progressively, an amorphous, granular material formed and extended between the hydroxyapatite aggregates. Osteoblastic cells then synthesized an osteoid matrix which mineralized on the first formed granular collagen free layer, following a classical pattern of calcification . Demineralization of ultrathin sections confirmed the presence of this interface between the material and bone tissue formed in vitro

Cooled Beam Diagnostics on LEIR

Electron cooling is central in the preparation of dense bunches of lead beams for the LHC. Ion beam pulses from the LINAC3 are transformed into short highbrightness bunches using multi-turn injection, cooling and accumulation in the Low Energy Ion Ring, LEIR [1]. The cooling process must therefore be continuously monitored in order to guarantee that the lead ions have the required characteristics in terms of beam size and momentum spread. In LEIR a number of systems have been developed to perform these measurements. These include Schottky diagnostics, ionisation profile monitors and scrapers. Along with their associated acquisition and analysis software packages these instruments have proved to be invaluable for the optimisation of the electron cooler

Morphology and stability of Au nanoclusters in HOPG nanopits of well-defined depth

Gold nanoparticles with a diameter comprised between 4 and 6 nm are stabilized in nanosized pits of well defined depth in highly oriented pyrolytic graphite (HOPG). These pits are produced by creation of artificial defects, followed by etching under a controlled oxygen atmosphere. At low Au coverage, clusters are found on the edges of the hexagonal pits maximizing the contact to dangling bonds on graphite multisteps. Larger coverage results in Au beads of surprisingly well defined shape and with a constant bead density per unit length. Most remarkable is the stability of these nanostructures under ambient conditions. Temperatures as high as 650 K do not alter the morphology of the gold clusters. Higher temperatures do not lead to a change of the cluster morphology but to catalytically driven etching of the HOPG substrate

Overturning established chemoselectivities : selective reduction of arenes over malonates and cyanoacetates by photoactivated organic electron donors

The prevalence of metal-based reducing reagents, including metals, metal complexes, and metal salts, has produced an empirical order of reactivity that governs our approach to chemical synthesis. However, this reactivity may be influenced by stabilization of transition states, intermediates, and products through substrate-metal bonding. This article reports that in the absence of such stabilizing interactions, established chemoselectivities can be overthrown. Thus, photoactivation of the recently developed neutral organic superelectron donor 5 selectively reduces alkyl-substituted benzene rings in the presence of activated esters and nitriles, in direct contrast to metal-based reductions, opening a new perspective on reactivity. The altered outcomes arising from the organic electron donors are attributed to selective interactions between the neutral organic donors and the arene rings of the substrates

A cadeia produtiva da uva de mesa do Nordeste do Brasil.

Caracterizacao da cadeia produtiva da uva; descricao da cadeia produtiva; analise de desempenho da cadeia produtiva; demandas prioritarias; proximos passos para a analise prognostica

Mutation of the palmitoylation site of estrogen receptor alpha in vivo reveals tissue-specific roles for membrane versus nuclear actions

Estrogen receptor alpha (ERalpha) activation functions AF-1 and AF-2 classically mediate gene transcription in response to estradiol (E2). A fraction of ERalpha is targeted to plasma membrane and elicits membrane-initiated steroid signaling (MISS), but the physiological roles of MISS in vivo are poorly understood. We therefore generated a mouse with a point mutation of the palmitoylation site of ERalpha (C451A-ERalpha) to obtain membrane-specific loss of function of ERalpha. The abrogation of membrane localization of ERalpha in vivo was confirmed in primary hepatocytes, and it resulted in female infertility with abnormal ovaries lacking corpora lutea and increase in luteinizing hormone levels. In contrast, E2 action in the uterus was preserved in C451A-ERalpha mice and endometrial epithelial proliferation was similar to wild type. However, E2 vascular actions such as rapid dilatation, acceleration of endothelial repair, and endothelial NO synthase phosphorylation were abrogated in C451A-ERalpha mice. A complementary mutant mouse lacking the transactivation function AF-2 of ERalpha (ERalpha-AF2(0)) provided selective loss of function of nuclear ERalpha actions. In ERalpha-AF2(0), the acceleration of endothelial repair in response to estrogen-dendrimer conjugate, which is a membrane-selective ER ligand, was unaltered, demonstrating integrity of MISS actions. In genome-wide analysis of uterine gene expression, the vast majority of E2-dependent gene regulation was abrogated in ERalpha-AF2(0), whereas in C451A-ERalpha it was nearly fully preserved, indicating that membrane-to-nuclear receptor cross-talk in vivo is modest in the uterus. Thus, this work genetically segregated membrane versus nuclear actions of a steroid hormone receptor and demonstrated their in vivo tissue-specific roles

Cadeia produtiva da uva de mesa no Nordeste.

O estudo da cadeia de uva de mesa na regiao Nordeste, visando a identificacao das demandas tecnologias, se baseou na metodologia do diagnostico rapido dos circuitos de comercializacao, no levantamento de dados estatisticos, em entrevistas com os principais agentes envolvidos, do produtor ate o consumidor e em visitas de campo e as feiras. Dentre as tres principais regioes brasileiras de destaque no cultivo de parreiras (Sudeste, Sul e Nordeste), o sertao nordestino se sobressai pela expansao da area cultivada de uva de mesa fina, concentrando-se no submedio do Sao Francisco. Em 1996, 113.013 toneladas foram produzidas nessa regiao, representando 27% da producao nacionial e um volume de negocios acima de 90 milhoes de reais. Observou-se uma diversidade de produtores de uva de mesa representada em cinco categorias: pequenos agricultores nao especializados; pequenas e medias empresas. Essa tipologia permite identificar logicas distintas de manejo, assim como problemas e potencialidades especificas de cada categoria, no tocante a producao e comercializacao. Dos produtores de uva, 70% sao pequenos agricultores, embora detenham apenas 17% da area cultivada. O mercado brasileiro de uva de mesa, marcado nos ultimos anos por um forte crescimento, constitui atualmente o terceiro maior mercado mundial, superando o Japao e paises da Europa. 95% da producao de uva da regiao Nordeste e destinada para o mercado interno. A cadeia de comercializacao de uva envolve atacadistas, cooperativas e outras organizacoes da intermediacao como os supermercados, que estao ganhando importancia na regiao. Os principais pontos de estrangulamento na cadeis produtiva de uva sao: a predominancia de uva Italia, quando a demanda do mercado e por uva sem sementes ou por "compra casada", envolvendo tres variedades de diferentes coloracoes; as pessimas condicoes de conservacao da malha rodoviaria que implicam negativamente sobre os custos de comercializacao e na qualidade da uva; o elevado custo de producao da regiao (em torno de R$ 400,00/ t); a ausencia de barreiras fitossanitarias; a falta de padronizacao da producao; e a ausencia de organizacao dos pequenos e medios produtores, principalmente para comercializacao e aquisicao de financiamentos para custeios e investimentos. Estes aspectos permitiram a definicao das demandas tecnologicas e nao tecnologicas, a serem implementadas a curto, medio e longo prazos

Nutrition rehabilitation of undernourished children utilizing Spiruline and Misola

BACKGROUND: Malnutrition constitutes a public health problem throughout the world and particularly in developing countries. AIMS: The objective of the study is to assess the impact of an elementary integrator composed of Spiruline (Spirulina platensis) and Misola (millet, soja, peanut) produced at the Centre Medical St Camille (CMSC) of Ouagadougou, Burkina Faso, on the nutritional status of undernourished children. MATERIALS AND METHODS: 550 undernourished children of less than 5 years old were enrolled in this study, 455 showed severe marasma, 57 marasma of medium severity and 38 kwashiorkor plus marasma. We divided the children randomly into four groups: 170 were given Misola (731 ± 7 kcal/day), 170 were given Spiruline plus traditional meals (748 ± 6 kcal/day), 170 were given Spiruline plus Misola (767 ± 5 kcal/day). Forty children received only traditional meals (722 ± 8 kcal/day) and functioned as the control group. The duration of this study was eight weeks. RESULTS AND DISCUSSION: Anthropometrics and haematological parameters allowed us to appreciate both the nutritional and biological evolution of these children. The rehabilitation with Spiruline plus Misola (this association gave an energy intake of 767 ± 5 kcal/day with a protein assumption of 33.3 ± 1.2 g a day), both greater than Misola or Spiruline alone, seems to correct weight loss more quickly. CONCLUSION: Our results indicate that Misola, Spiruline plus traditional meals or Spiruline plus Misola are all a good food supplement for undernourished children, but the rehabilitation by Spiruline plus Misola seems synergically favour the nutrition rehabilitation better than the simple addition of protein and energy intake