Comportamento em desgaste por erosão cavitação, erosão - corrosão e em ensaios de microesclerometria linear instrumentada de um aço inoxidável martensítico AISI 410 nitretado a plasma em baixa temperatura, utilizando a tecnologia de tela ativa.

Amostras de um aço inoxidável martensítico AISI 410 temperado e revenido foram nitretadas a plasma em baixa temperatura usando o tratamento de nitretação plasma DC e a nitretação a plasma com tela ativa. Ambos os tratamentos foram realizados a 400 °C, utilizando mistura gasosa de 75 % de nitrogênio e 25 % de hidrogênio durante 20 horas e 400 Pa de pressão. As amostras de aço AISI 410 temperado e revenido foram caracterizadas antes e depois dos tratamentos termoquímicos, usando as técnicas de microscopia óptica, microscopia eletrônica de varredura, medidas de microdureza, difração de raios X e medidas de teor de nitrogênio em função da distância à superfície por espectrometria WDSX de raios X. A resistência à erosão por cavitação do aço AISI 410 nitretado DC e com tela ativa foi avaliada segundo a norma ASTM G32 (1998). Os ensaios de erosão, de erosão - corrosão e de esclerometria linear instrumentada segundo norma ASTM C1624 (2005) somente foram realizados no aço AISI 410 nitretado com tela ativa. Ensaios de nanoindentação instrumentada forma utilizados para medir a dureza (H) e o módulo de elasticidade reduzido (E*) e calcular as relações H/E* e H3/E*2 e a recuperação elástica (We), utilizando o método proposto por Oliver e Pharr. Ambos os tratamentos produziram camadas nitretadas de espessura homogênea constituídas por martensita expandida supersaturada em nitrogênio e nitretos de ferro com durezas superiores a 1200 HV, porém, a nitretação DC produziu maior quantidade de nitretos de ferro do que o tratamento de tela ativa. Os resultados de erosão por cavitação do aço nitretado DC mostraram que a precipitação de nitretos de ferro é prejudicial para a resistência à cavitação já que reduziu drasticamente o período de incubação e aumentou a taxa de perda de massa nos estágios iniciais do ensaio; entretanto, depois da remoção desses nitretos de ferro, a camada nitretada formada somente por martensita expandida resistiu bem ao dano por cavitação. Já no caso do aço nitretado com tela ativa, a resistência à erosão por cavitação aumentou 27 vezes quando comparada com o aço AISI 410 sem nitretar, fato atribuído à pequena fração volumétrica e ao menor tamanho dos nitretos de ferro presente na camada nitretada, às maiores relações H/E* e H3/E*2 e à alta recuperação elástica da martensita expandida. A remoção de massa ocorreu, principalmente, pela formação de crateras e de destacamento de material da superfície dos grãos por fratura frágil sem evidente deformação plástica. As perdas de massa acumulada mostradas pelo aço nitretado foram menores do que aquelas do aço AISI 410 nos ensaios de erosão e de erosão corrosão. O aço nitretado apresentou uma diminuição nas taxas de desgaste em ambos os ensaios de aproximadamente 50 % quando comparadas com o aço AISI 410. O mecanismo de remoção de material foi predominantemente dúctil, mesmo com o grande aumento na dureza. Os resultados de esclerometria linear instrumentada mostraram que a formação de martensita expandida possibilitou uma diminuição considerável do coeficiente de atrito em relação ao observado no caso do aço AISI 410 sem nitretar. O valor de carga crítica de falha foi de 14 N. O mecanismo de falha operante no aço nitretado foi trincamento por tensão.

Contribution of changes in risk factors to the decline of coronary heart disease mortality in Australia over three decades

BACKGROUND: Coronary heart disease has been a major cause of mortality in Australian adults, but the rate has declined by 83% from the 1968 peak by the year 2000. The study objective is to determine the contribution of changes in population risk factors - mean serum cholesterol and diastolic blood pressure and tobacco smoking prevalence - to the decline in coronary heart disease mortality in Australia over three decades. METHODS: Coronary heart disease deaths (International Classification of Disease-9, 410-414) and population by year, age group and sex were obtained from the Australian Bureau of Statistics. Risk factor levels were obtained from population surveys and estimated average annual changes by period were used to calculate average annual 'attributable' proportional declines in CHD mortality by period (age 35-64 years). RESULTS: Over the period 1968-2000, 74% of male decline and 81% of the female decline in coronary heart disease mortality rate was accounted for by the combined effect of reductions in the three risk factors. In males 36% of the decline was contributed by reductions in diastolic blood pressure, 22% by cholesterol and 16% by smoking. For females 56% was from diastolic blood pressure reduction, 20% from cholesterol and 5% from smoking. Effects of reductions in serum cholesterol on coronary heart disease mortality occurred mainly in the 1970s. Declines in diastolic blood pressure had effects on coronary heart disease mortality over the three decades, and declines in tobacco smoking had a significant effect in males in the 1980s. CONCLUSION: Most of the spectacular decline in coronary heart disease mortality over the last three decades in Australia can be ascribed to reductions in population risk factors from primary and secondary prevention.

Numerical and experimental analysis of sensitivity-enhanced RI sensor based on Ex-TFG in thin cladding fiber

We report a highly sensitive refractive index (RI) sensor in the aqueous solution, which is based on an 81°-tilted fiber grating structure inscribed into a thin cladding fiber with 40 μm cladding radius. The numerical analysis has indicated that the RI sensitivity of cladding resonance mode of the grating can be significantly enhanced with reducing cladding size. This has been proved by the experimental results as the RI sensitivities of TM and TE resonance peaks in the index region of 1.345 have been increased to 1180 nm/RIU and 1150 nm/RIU, respectively, from only 200 and 170 nm/RIU for the same grating structure inscribed in standard telecom fiber with 62.5-μm cladding radius. Although the temperature sensitivity has also increased, the change in temperature sensitivity is still insignificant in comparison with RI sensitivity enhancement.

Current situation and perspectives of school libraries in Costa Rica

Costa Rica is a small country located in Central America, with an area of 51,100 square kilometers and a population of 2,192,410 inhabitants. The highest percentage of national budget, 26.73%, is dedicated to education. There are currently 360 kindergarten, schools and 317 colleges 3001, considering the different modes: academic, technical, agricultural, industrial, craft and art. These figures mean a huge effort for Costa Rican society is worth now the question what the country looks so large an investment? and what role school libraries are doing in achieving the goals of Education of Costa Rica? I believe unequivocally that those who lead us today reciprocated school libraries, we encourage the same spirit that is well expressed in the famous document UNESCO1. "Learning to Be".

Beyond sanctions : is there a need to treat first-time offenders?

Aims: Driving Under the Influence (DUI) enforcement can be a broad screening mechanism for alcohol and other drug problems. The current response to DUI is focused on using mechanical means to prevent inebriated persons from driving, with little attention the underlying substance abuse problems. ---------- Methods: This is a secondary analysis of an administrative dataset of over 345,000 individuals who entered Texas substance abuse treatment between 2005 and 2008. Of these, 36,372 were either on DUI probation, referred to treatment by probation, or had a DUI arrest in the past year. The DUI offenders were compared on demographic characteristics, substance use patterns, and levels of impairment with those who were not DUI offenders and first DUI offenders were compared with those with more than one past-year offense. T tests and chi square tests were used to determine significance. ---------- Results: DUI offenders were more likely to be employed, to have a problem with alcohol, to report more past-year arrests for any offense, to be older, and to have used alcohol and drugs longer than the non-DUI clients who reported higher ASI scores and were more likely to use daily. Those with one past-year DUI arrest were more likely to have problems with drugs other than alcohol and were less impaired than those with two or more arrests based on their ASI scores and daily use. Non-DUI clients reported higher levels of mood disorders than DUIs but there was no difference in their diagnosis of anxiety. Similar findings were found between those with one or multiple DUI arrests. ----------Conclusion: Although first-time DUIs were not as impaired as non-DUI clients, their levels of impairment were sufficient to cause treatment. Screening and brief intervention at arrest for all DUI offenders and treatment in combination with abstinence monitoring could decrease future recidivism.

Work zone items influencing driver speeds at roadworks: worker, driver and expert perspectives

Roadworks are essential to a safe and efficient road network, yet somewhat paradoxically the necessary work is often associated with increased risk to motorists and workers, as well as with traffic flow disruptions. A major source of increased crash risk at roadwork sites (work zones) is poor speed limit compliance. Speeding in work zones is examined in existing literature to the extent that major issues are known and some effective countermeasures are identified. However, as speeding remains a major problem in work zones, influences on driver behaviour arguably need to be better understood to achieve greater compliance and thus realise further gains in road safety. Current research on safety at Queensland roadwork sites has examined the views of workers, measured work zone speed profiles, and conducted an online survey of drivers (N=410). This paper focuses on survey participants’ ratings of 12 specific work zone items (including traffic control measures) in terms of their influence on speed choice. Repeated measures ANOVA revealed statistically significant differences (p<0.001) in the ratings of these items, with the most influential including visible presence of workers, visible police presence, and speed feedback displays. Those rated least influential included ’roadwork speed limits are enforced’ and ‘reduce speed’ signs and increased fines for speeding in work zones. The paper considers the alignment of these findings with those from other sources, including worker interviews and the literature, to provide a consolidated assessment of the influence of work zone items on driver speeds.

Electron-hole recombination in cobalt-doped p-type germanium

The recombination properties of cobalt centers in p-type germanium containing cobalt in the concentration range 1014 to 1016 atoms/cm3 have been investigated. The measurement of lifetime has been carried out by steady-state photoconductivity and photo-magneto-electric methods in the temperature range 145 to 300°K. The cross-sections Sno (electron capture cross-section at neutral centers). Sn- (electron capture cross-section at singly negatively charged centers) and their temperature variations have been estimated by the analysis of the lifetime data on the basis of Sah-Shockley's multi-level formula. The value of Sno is (15±5).10-16 cm2 and is temperature independent. The value of Sn- is ≈4·10-16 cm2 around 225°K and it increases with increase of temperature. The possible mechanisms for capture at neutral and repulsive centers are discussed and a summary of the capture cross-sections for cobalt centers is given. A comparison of the cross-section values of cobalt and their temperature variations with those of the related impurities-manganese, iron and nickel-in germanium has been made.

新型多氮杂环金属配合物的合成及其光谱研究

采用溶液析出法,合成了以2-（2′-羟基-5′-甲基苯基）苯并三唑（HMPB）为配体的多氮杂环金属配合物M（HMPB）2（M=Co,Ni）,利用元素分析、激光解析飞行时间质谱等进行了表征,并研究了新配合物的红外特征光谱和紫外-可见电子吸收光谱。结果表明：HMPB配体通过N和O原子与中心金属以二齿形式配位,中心金属的配位数为4;配合物红外特征吸收谱带位于400～2 500 cm^-1,形成金属配合物后,2-（2′-羟基-5′-甲基苯基）苯并三唑的羟基的伸缩振动吸收、CN振动峰和C─O特征吸收有明显改变,同时确定了配位键M─N和M─O的特征峰位置;配合物在紫外区有强吸收,其最大吸收峰位于335～345 nm。

Illness and elevated Human Mortality in Europe Coincident with the Laki Fissure eruption

Grattan, J. Durand, M. Taylor, S., Illness and elevated Human Mortality in Europe Coincident with the Laki fissure eruption. In: 'Volcanic Degassing: Geological Society, Special Publication 213', Oppenheimer, C., Pyle, D.M. and Barclay, J. (eds). Geological Society, London, Special Publications, 410-414, 2003.

Motivational differences in science course enrolment shown by males and females in grades 9 through OAC

A sample of 1,345 students enrolled in advanced-level science courses from Grades 9 through OAe was surveyed in order to gain perspective into the existence of motivational differences attributing to science course enrolment by gender. Records of enrolment were examined in order to detect patterns and trends. A questionnaire was devised and piloted. It measured five motivational variables - demographics, science and science-related experiences, science ability and attitudes, impressions about women in science, and importance of science and science-related skills. The students also provided some impressions about the image of scientists. Results of the questionnaire were analyzed for frequency of responses and for significant gender differences using the chi-square. Differences were found to exist in the areas of science anxiety as it relates to testing and oral participation; in motivation generated by the performance of extra-curricular science and science-related activities, and by the classroom environment; in impressions of women in science; in the importance of science skills, and in the area of teacher influence. The study also showed a differential enrolment of females, with an emphasis on biology and chemistry. The males were enrolled in courses of physics and chemistry. The findings lead to numerous suggested strategies and programs for encouraging the participation of females in science education and careers.

Banana waste as substrate for a-amylase production by Bacillus subtilis (CBTK 106) under solid-state fermentation

Bacillus subtilis CBTK 106, isolated from banana wastes, produced high titres of a-amylase when banana fruit stalk was used as substrate in a solid-state fermentation system. The e¤ects of initial moisture content, particle size, cooking time and temperature, pH, incubation temperature, additional nutrients, inoculum size and incubation period on the production of a- amylase were characterised. A maximum yield of 5 345 000 U mg~1 min~1 was recorded when pretreated banana fruit stalk (autoclaved at 121 ¡C for 60 min) was used as substrate with 70% initial moisture content, 400 lm particle size, an initial pH of 7.0, a temperature of 35 ¡C, and additional nutrients (ammonium sulphate/sodium nitrate at 1.0%, beef extract/peptone at 0.5%, glucose/sucrose/starch/maltose at 0.1% and potassium chloride/sodium chloride at 1.0%) in the medium, with an inoculum-to-substrate ratio of 10% (v/w) for 24 h. The enzyme yield was 2.65-fold higher with banana fruit stalk medium compared to wheat bran

Convergencia de vías de señalización en un modelo de apoptosis

La sepsis es un evento inflamatorio generalizado del organismo inducido por un daño causado generalmente por un agente infeccioso. El patógeno más frecuentemente asociado con esta entidad es el Staphylococcus aureus, responsable de la inducción de apoptosis en células endoteliales debida a la producción de ceramida. Se ha descrito el efecto protector de la proteína C activada (PCA) en sepsis y su relación con la disminución de la apoptosis de las células endoteliales. En este trabajo se analizó la activación de las quinasas AKT, ASK1, SAPK/JNK y p38 en un modelo de apoptosis endotelial usando las técnicas de Western Blotting y ELISA. Las células endoteliales (EA.hy926), se trataron con C2-ceramida (130μM) en presencia de inhibidores químicos de cada una de estas quinasas y PCA. La supervivencia de las células en presencia de inhibidores químicos y PCA fue evaluada por medio de ensayos de activación de las caspasas 3, 7 y 9, que verificaban la muerte celular por apoptosis. Los resultados evidencian que la ceramida reduce la activación de AKT y aumenta la activación de las quinasas ASK, SAPK/JNK y p38, en tanto que PCA ejerce el efecto contrario. Adicionalmente se encontró que la tiorredoxina incrementa la activación/fosforilación de AKT, mientras que la quinasa p38 induce la defosforilación de AKT.

An approach to generalized holomorphic functions

A study of the generalized holomorphic functions, HG(Omega), having in mind its strict elements, i.e. those which are in HG(Omega) - H(Omega), as well as the possibility of the existence of hybrid elements, i.e. elements which have, in a part of a domain Omega subset of C-n, the strict behaviour and, in another part of the same domain, the classical behaviour, is carried out in this work. The study of hybrid elements is important in the approach of a concept of generalized domain of holomorphy.

Efeitos da temperatura de incubação e da idade da matriz no desenvolvimento in ovo, qualidade, desempenho e produção de ovos da progênie de codornas japonesas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Variações motivacionais no ensino de inglês em contexto de escola pública

Pós-graduação em Estudos Linguísticos - IBILCE