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Search Results: 1 - 10 of 305301 matches for " J. Rocha "
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Simple General Purpose Ion Beam Deceleration System Using a Single Electrode Lens  [PDF]
J. Lopes, J. Rocha
World Journal of Engineering and Technology (WJET) , 2015, DOI: 10.4236/wjet.2015.33014
Abstract: Ion beam deceleration properties of a newly developed low-energy ion beam implantation system were studied. The objective of this system was to produce general purpose low-energy (5 to 15 keV) implantations with high current beam of hundreds of μA level, providing the most wide implantation area possible and allowing continuously magnetic scanning of the beam over the sample(s). This paper describes the developed system installed in the high-current ion implanter at the Laboratory of Accelerators and Radiation Technologies of the Nuclear and Technological Cam-pus, Sacavém, Portugal (CTN).
Denseness of ergodicity for a class of partially hyperbolic volume-preserving flows
M. Bessa,J. Rocha
Mathematics , 2007,
Abstract: This paper has been withdrawn by the authors due to a mistake in one of the proofs
On C1-robust transitivity of volume-preserving flows
M. Bessa,J. Rocha
Mathematics , 2007,
Abstract: We prove that a divergence-free and C1-robustly transitive vector field has no singularities. Moreover, if the vector field is C4 then the linear Poincare flow associated to it admits a dominated splitting over M.
Use of ionic liquids in biodiesel production: a review
Andreani, L.;Rocha, J. D.;
Brazilian Journal of Chemical Engineering , 2012, DOI: 10.1590/S0104-66322012000100001
Abstract: this paper discusses the feasibility of the use of ionic liquids as catalysts in the biodiesel production field, describing some studies already published in the literature on this theme. ionic liquids are regarded as a new generation of catalysts in the chemical industry, with several uses in different commercial segments. however only a few publications involving this topic can be found in the literature addressing the manufacture of biodiesel from vegetable oils or animal fats. through the analysis of the data generated in the studies reviewed, it is possible to affirm that ionic liquids present great potential as catalysts for biodiesel production, but there are some challenges to be faced, such as the production of ionic liquids with low cost, easy recovery and with the possibility of reutilization of the catalyst for several cycles.
Producción de vitamina B12 por Methanosarcina sp. utilizando metanol y acetato como fuente de carbono
Facundo J. Márquez Rocha
Revista de la Sociedad Química de México , 2000,
Abstract: Se aislaron 2 cepas del género Methanosarcina con la capacidad de utilizar simultáneamente metanol y acetato como fuente de carbono. La velocidad máxima de producción de CH4 fue de 1.43 (cepa C1) y 1.30 mmol h 1 (cepa C2), a una concentración de acetato de 100 y 200 mM, respectivamente. La cepa C2 fue más resistente a concentraciones mayores de acetato (> 150 mM). Los rendimientos de CH4 para las cepas C1 y C2 fueron de 0.45 y 0.46 mmolCH4 mmolMOH 1, respectivamente. Ambas cepas rinden mayor producción de vitamina B12 extracelular a una concentración de acetato de 50- 150 mM, aunque la cantidad en C2 (9 mg L 1h 1 ) es 1.8 veces más que en C1 (5 mg L 1 h 1).
Hospitaliza??o: efeito sobre o estado nutricional em crian?as
Rocha, Geila A.;Rocha, Edmundo J. M.;Martins, Ceci V.;
Jornal de Pediatria , 2006, DOI: 10.2223/JPED.1440
Abstract: objective: to evaluate the nutritional status of children at hospital admission and again at hospital discharge and to investigate factors associated with the onset and/or exacerbation of malnutrition. method: an observational study of 203 children under 5 years old admitted to a hospital in the city of fortaleza between august and december 2003. nutritional status, expressed in z-scores for weight/age, stature/age and weight/stature, was compared at the time of admission and on hospital discharge and broken down by sex, age, condition responsible for hospitalization and length of hospital stay. results: on admission prevalence rates for moderate and/or severe malnutrition (z-score < -2) were 18.7, 18.2 and 6.9%, for weight/age, stature/age and weight/stature, respectively. during their stay in hospital 51.6% of the 186 children who completed the study lost weight, with most weight being lost by those with prolonged hospital stays and pneumonia as the disease responsible for their hospitalization. children who had malnutrition on admission were still malnourished at hospital discharge and 10 (9.17%) well-nourished children developed mild malnutrition while hospitalized. conclusions: the prevalence of malnutrition at the time of admission was elevated and remained unchanged by discharge. prolonged hospitalization and pneumonia were linked with weight loss in hospital.
Hospitaliza o: efeito sobre o estado nutricional em crian as
Rocha Geila A.,Rocha Edmundo J. M.,Martins Ceci V.
Jornal de Pediatria , 2006,
Abstract: OBJETIVO: Avaliar o estado nutricional de crian as, por ocasi o da admiss o e da alta hospitalar, e fatores associados com o aparecimento e/ou agravamento da desnutri o MéTODO: Estudo observacional de 203 crian as, menores de 5 anos de idade, internadas em um hospital na cidade de Fortaleza, entre agosto e dezembro de 2003. Comparou-se o estado nutricional, expresso em escore z, dos índices peso/idade, estatura/idade e peso/estatura no momento da admiss o e da alta hospitalar, de acordo com sexo, idade, doen a que motivou a interna o e tempo de permanência no hospital. RESULTADOS: Na admiss o, as prevalências de desnutri o moderada e/ou grave (< -2 z escore) foram 18,7, 18,2 e 6,9%, para os índices peso/idade, estatura/idade e peso/estatura, respectivamente. Das 186 crian as que completaram o estudo, 51,6% apresentaram perda ponderal, em especial as que tiveram interna o prolongada e pneumonia como doen a determinante da interna o. Na alta hospitalar, as crian as com desnutri o permaneceram com seu estado nutricional inalterado, e 10 (9,17%) eutróficas evoluíram para desnutri o leve. CONCLUS ES: A prevalência de desnutri o à admiss o foi elevada, permanecendo inalterada por ocasi o da alta. Hospitaliza o prolongada e pneumonia associaram-se à perda de peso durante a interna o.
Weighted kneading theory of one-dimensional maps with a hole
J. Leonel Rocha,J. Sousa Ramos
International Journal of Mathematics and Mathematical Sciences , 2004, DOI: 10.1155/s016117120430428x
Abstract: The purpose of this paper is to present a weighted kneading theory for one-dimensional maps with a hole. We consider extensions of the kneading theory of Milnor and Thurston to expanding discontinuous maps with a hole and introduce weights in the formal power series. This method allows us to derive techniques to compute explicitly the topological entropy, the Hausdorff dimension, and the escape rate.
Ensayos de desempe?o para la selección de esquemas de pinturas en las atmósferas de la Paz y Santa Cruz
Rocha,J. A.; Velarde,J.; Rozovic,I.;
Corros?o e Protec??o de Materiais , 2007,
Abstract: during three years starting december of 2000, carried out performance tests of 48 paint schemes in la paz and santa cruz cities in bolivia, inside the iimetmat-umsa/monopol project. based on the results of atmosphere characterization, carried out at the same time of the performance tests, it is possible to ratify the environmental differences between these two cities. as product of these environmental differences, the performance of paint schemes were in the same way. it represents a very important knowledge when the selection of paints schemes must to do, for use in one of these two atmospheres.
Transcriptional regulation of genes involved in terpenoid índole alkaloid production in Catharanthus roseus seedlings Regulación transcripcional de genes involucrados en la producción de alcaloides indol-terpenoides en plántulas de Catharanthus roseus
Rocha Pedro J.,Leech Mark J.
Revista Colombiana de Biotecnología , 2002,
Abstract: Catharanthus roseus (L.) G Don is a medicinal plant that produces a variety of terpenoid indole alkaloids (TIAs), some of which display pharmacological activity. C. roseus plants and cell cultures have been used to elucidate the TIAs biosynthetic pathway. A considerable number or enzymes have also been characterised, and their respective genes cloned. TIAs production in C. roseus plant and cell cultures is highly regulated at transcriptional-, develop-mental-, and environmental-level. Studies into TIAs biosynthetic gene regulation have been carried out using cell cultures. However, regulation in plants is almost unknown. Here, biosynthetic genes idc, strl, d4h and dat expres-sion levels are qualitatively examined in a developmental series of C. roseus seedlings. The effect of water- and light-stress and methyl jasmonate (MeJa) and acetyl salicylic acid (ASA) elicitation is also examined. Comparison between seedlings and cell cultures strongly suggests that TIAs biosynthetic gene transcriptional regulation is different in C.roseus plants and cell cultures. Cathmnthus roseus es una planta medicinal productora de varios alcaloides indol terpenoides (AIT) con actividad farmacológica. Empleando plantas y cultivos celulares de C. roseus la ruta biosintética de AIT ha sido determinada, además, un considerable número de sus enzimas ha sido caracterizado y sus respectivos genes clonados. La producción de AIT en plantas y cultivos celulares de C. roseus está altamente regulada a nivel transcripcional, es dependiente de los estados de desarrollo y puede ser alterada, entre otros factores, por sometimiento a estrés luminoso y tratamiento con elicitores bióticos y abióticos. Estudios sobre la regulación de los genes involucrados en la biosíntesis de AIT han sido llevados a cabo en cultivos celulares, sin embargo poco se conoce acerca de la regulación de los mismos en plantas. En los experimentos reportados aqui, se presenta un examen cualitativo de los niveles de expresión de los genes idcr strl, d4h y dat que codifican enzimas importantes en la biosíntesis de AIT en plántulas de C. roseus en una serie de desarrollo que comprende O a 18 días. Además, se analiza el efecto del estrés hídrico, luminoso y de la elicitación con metil jasmonato (Meja) y ácido acetil salicílico (ASA). La comparación entre la evidencia experimental obtenida con plántulas en el presente artículo y los datos reportados en estudios con suspensiones celulares sugiere que la regulación transcripcional de algunos genes difiere de manera considerable.
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