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Search Results: 1 - 10 of 486058 matches for " R. S. Rimada "
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Solvent and Substituent Effects on the Thermolysis of Antimalarial Fluorophenyl Substituted 1,2.4-Trioxanes
Lazaro F. R. Cafferata,Ruben S. Rimada
Molecules , 2003, DOI: 10.3390/80900655
Abstract: The kinetics and mechanism of the thermal decomposition reaction of cis-6-(4-fluoropheny1)-5,6-[2-(4-fluorophenyl)-propylidene]-3,3-tetramethylene-l,2,4-trioxacyclohexane (I) were investigated separately in n-hexane and in methanol solutions over the temperature and concentration ranges of 393.2-443.2 K and 2.7-54 x l0-5 M, respectively. The values of the activation parameters for both reactions were compared with the corresponding ones for the thermolysis of cis-6-(4-fluorophenyl-5,6-[2-(4-fluorophenyl)-3-hydroxypropylidene]-3,3-tetramethylene-1,2,4-trioxacyclohexane (II), investigated in the same solvents and temperature range. Substituent and solvent effects on the initial homolytic rupture of the O-O peroxydic bonds of those molecules were evaluated.
Conformational equilibrium of the thermal unimolecular decomposition reactions of substituted 4-fluorophenyl 1,2,4-trioxanes
Cafferata,L.F.R; Rimada,R.S; Jubert,A.H.;
Anales de la Asociaci?3n Qu?-mica Argentina , 2005,
Abstract: the unimolecular fragmentations of two fluorine substituted 1,2,4-trioxanes molecules had been interpreted considering the experimental activation parameters of the thermal decomposition reactions in solution. the kinetic data can be rationalized through the postulation of conformational equilibrium of each of the cis-6-(4-fluorophenyl)-5,6-[2-(4- fluorophenyl)-propyliden-3,3-tetramethylene-1,2,4-trioxacyclohexane (i) and cis-6-(4- fluorophenyl)-5,6-[2-(4-fluorophenyl)]-3-hydroxipropyliden-3,3-tetramethylene-1,2,4- trioxacyclohexane (ii) molecules, which would originate intermediate diradicals in their thermolysis in methanol and in n-hexane solutions. the kinetics data and spectroscopic (uv) studies already reported are in close agreement with an ab-initio dft level calculation performed on those molecules.
Isolation, characterization and quantification of artemisinin by NMR from Argentinean Artemisia annua L.
Rubén S. RIMADA,Walter O. GATTI,René JEANDUPEUX,Lázaro F. R. CAFFERATA
Boletín Latinoamericano y del Caribe de Plantas Medicinales y Aromáticas , 2009,
Abstract: Artemisinina es una lactona policíclica sesquiterpénica presente junto a otros metabolitos en hojas e inflorescencias de Artemisia annua L. Esra sustancia es muy eficaz contra cepas resistentes de Plasmodium falciparum, agente etiológico de la forma más grave de malaria. En este trabajo se modificaron y optimizaron procedimientos ya conocidos para la extracción y aislamiento de artemisinina. Se efectuaron extracciones a temperatura ambiente con diferentes solventes y/o mezclas de los mismos. Se describen técnicas cromatográficas (TLC, GC y HPLC) y espectroscópica (NMR) empleadas en la caracterización y su control de calidad en los diferentes extractos. La conveniencia de la realización de esos procedimientos se evaluó críticamente por comparación de sus resultados con los obtenidos aplicando los métodos clásicos de aislamiento por extracción Soxhlet a mayores temperaturas. El contenido de artemisinina en los extractos estuvo en el rango de 0,2-0,3 %.(p/p).
Thermal Decomposition Reaction of cis-6-Phenyl-5,6-(2-phenylpropilydene)-3,3-tetramethylene-1,2,4-trioxacyclohexane in Different Solvents
L. F. R. Cafferata,G. N. Eyler,A. I. Ca?izo,C. M. Mateo,R. S. Rimada
Molecules , 2000, DOI: 10.3390/50300362
Abstract: The kinetics of the thermal decomposition reaction of cis-6-phenyl-5,6-(2-phenyl-propilydene)-3,3-tetramethylene-1,2,4-trioxacyclohexane (I) was investigated in the temperature range of 100-130°C in selected solvents of different physicochemical properties to evaluate a solvent effect on the reaction.
Modeling Multiple Quantum Well and Superlattice Solar Cells  [PDF]
Carlos I. Cabrera, Julio C. Rimada, Maykel Courel, Luis Hernandez, James P. Connolly, Agustín Enciso, David A. Contreras-Solorio
Natural Resources (NR) , 2013, DOI: 10.4236/nr.2013.43030
Abstract:

The inability of a single-gap solar cell to absorb energies less than the band-gap energy is one of the intrinsic loss mechanisms which limit the conversion efficiency in photovoltaic devices. New approaches to ultra-high efficiency solar cells include devices such as multiple quantum wells (QW) and superlattices (SL) systems in the intrinsic region of a p-i-n cell of wider band-gap energy (barrier or host) semiconductor. These configurations are intended to extend the absorption band beyond the single gap host cell semiconductor. A theoretical model has been developed to study the performance of the strain-balanced GaAsP/InGaAs/GaAs MQWSC, and GaAs/GaInNAs MQWSC or SLSC. Our results show that conversion efficiencies can be reached which have never been obtained before for a single-junction solar cell.

Problemas bioéticos que se desprenden en la atención a las personas viviendo con VIH/sida
Martínez Bernal,Ida; Rimada álvarez,Yahcel T; Vera Santos,Carmen;
Revista M??dica Electr?3nica , 2010,
Abstract: hiv/aids is currently a serious problem around the world. it is an entity inexorably leading to death in a more or less long term. in a general sense, all the sexual active population is vulnerable to this kind of disease. there are some bioethical aspects related with this disease that our society has to affront like confidentiality, resources distribution, the usage of human beings in experiments, the development of sanitary measures for schools, work settings, prisons, educative programs, detection programs, the informed consent, and society in general. among the missions our ministry of public health has to assume are: developing political willingly efforts to positive impacting on the stigmas associated to this disease, increasing health educative work to modify life styles, to develop conscience in people on how to avoid the disease, increasing the risk perception and promoting safe and responsible sexual practices, developing spiritual, cultural, ethical and moral values in the sexual education, and assuring high qualitative medical health care for diagnosed patients.
Problemas bioéticos que se desprenden en la atención a las personas viviendo con VIH/sida
Ida Martínez Bernal,Yahcel T Rimada álvarez,Carmen Vera Santos
Revista M??dica Electr?3nica , 2010,
Abstract: El VIH/sida constituye en el momento actual un serio problema a nivel mundial. Es una entidad que conduce inexorablemente a la muerte en un plazo más o menos largo. Y en sentido general, toda nuestra población en edad sexualmente activa es vulnerable a este tipo de afección. Existen una serie de aspectos bioéticos relacionados con la enfermedad a los cuales tiene que enfrentarse nuestra sociedad, entre ellos, la confidencialidad, la distribución de recursos, el uso de sujetos humanos en la experimentación, el desarrollo de medidas sanitarias para las escuelas, el lugar de trabajo, las prisiones, campa as educativas, campa as de detección, consentimiento informado, y la sociedad en general. Entre la misiones que tiene que asumir el Ministerio de Salud Pública en nuestro país se encuentran: desarrollar esfuerzos con voluntad politica para incidir positivamente en la lucha contra los estigma asociados a esta enfermedad, incrementar las labores educativas de salud para modificar estilos de vida, concientizar a las personas en cómo prevenir la enfermedad, aumentar la percepción de riesgo y fomentar prácticas sexuales seguras y responsables, desarrollar valores espirituales, culturales, éticos y morales en la educación sexual, y garantizar una atención médica de alta calidad una vez que se diagnostican los pacientes. HIV/AIDS is currently a serious problem around the world. It is an entity inexorably leading to death in a more or less long term. In a general sense, all the sexual active population is vulnerable to this kind of disease. There are some bioethical aspects related with this disease that our society has to affront like confidentiality, resources distribution, the usage of human beings in experiments, the development of sanitary measures for schools, work settings, prisons, educative programs, detection programs, the informed consent, and society in general. Among the missions our Ministry of Public Health has to assume are: developing political willingly efforts to positive impacting on the stigmas associated to this disease, increasing health educative work to modify life styles, to develop conscience in people on how to avoid the disease, increasing the risk perception and promoting safe and responsible sexual practices, developing spiritual, cultural, ethical and moral values in the sexual education, and assuring high qualitative medical health care for diagnosed patients.
Multiscale approaches to high efficiency photovoltaics
J. P. Connolly,Lejo J. Koduvelikulathu,D. Mencaraglia,Julio C. Rimada,Ahmed Nejim,G. Sanchez
Physics , 2015,
Abstract: While renewable energies are achieving parity around the globe, efforts to reach higher solar cell efficiencies becomes ever more difficult as they approach the limiting efficiency. The so-called third generation concepts attempt to break this limit through a combination of novel physical processes and new materials and concepts in organic and inorganic systems. Some examples of semi-empirical modelling in the field are reviewed, in particular for multispectral solar cells on silicon (french ANR project MULTISOLSI). Their achievements are outlined, and the limits of these approaches shown. This introduces the main topic of this contribution, which is the use of multiscale experimental and theoretical techniques to go beyond the semi-empirical understanding of these systems. This approach has already led to great advances at modelling which have led to modelling software which is widely known. Yet a survey of the topic reveals a fragmentation of efforts across disciplines, firstly, such as organic and inorganic fields, but also between the high efficiency concepts such as hot carrier cells and intermediate band concepts. We show how this obstacle to the resolution of practical research obstacles may be lifted by inter-disciplinary cooperation across length scales, and across experimental and theoretical fields, and finally across materials systems. We present a European COST Action MultiscaleSolar kicking off in early 2015 which brings together experimental and theoretical partners in order to develop multiscale research in organic and inorganic materials. The goal of this defragmentation and interdisciplinary collaboration is to develop understanding across length scales which will enable the full potential of third generation concepts to be evaluated in practise, for societal and industrial applications.
Economic Dispatch with Multiple Fuel Options Using CCF  [PDF]
R. Anandhakumar, S. Subramanian
Energy and Power Engineering (EPE) , 2011, DOI: 10.4236/epe.2011.32015
Abstract: This paper presents an efficient analytical approach using Composite Cost Function (CCF) for solving the Economic Dispatch problem with Multiple Fuel Options (EDMFO). The solution methodology comprises two stages. Firstly, the CCF of the plant is developed and the most economical fuel of each set can be easily identified for any load demand. In the next stage, for the selected fuels, CCF is evaluated and the optimal scheduling is obtained. The Proposed Method (PM) has been tested on the standard ten-generation set system; each set consists of two or three fuel options. The total fuel cost obtained by the PM is compared with earlier reports in order to validate its effectiveness. The comparison clears that this approach is a promising alterna-tive for solving EDMFO problems in practical power system.
Design of Multilingual Speech Synthesis System  [PDF]
S. SARASWATHI, R. VISHALAKSHY
Intelligent Information Management (IIM) , 2010, DOI: 10.4236/iim.2010.21008
Abstract: The main objective of this paper is to convert the written multilingual text into machine generated synthetic speech. This paper is proposed in order to provide a complete multilingual speech synthesizer for three languages Indian English, Tamil and Telugu. The main application of TTS system is that it will be helpful for blind and mute people that they could have the text read to them by computer. TTS system will help in retrieving the information from sites that contain information in different languages. It can be used in educational institutions for pronunciation teaching of different languages. We use concatenative speech syn-thesis where the segments of recorded speech are concatenated to produce the desired output. We apply prosody which makes the synthesized speech sound more like human speech. Smoothing is also done to smooth the transition between segments in order to produce continuous output. The Optimal Coupling algorithm is enhanced to improve the performance of speech synthesis system.
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