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Search Results: 1 - 10 of 378269 matches for " Rafael C. de; "
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Effect of Leuconostoc mesenteroides 11 bacteriocin in the multiplication control of Listeria monocytogenes 4b
Martinez, Rafael C. R.;Martinis, Elaine C. P. de;
Ciência e Tecnologia de Alimentos , 2006, DOI: 10.1590/S0101-20612006000100009
Abstract: the activity of a crude preparation of bacteriocin produced by the chicken meat isolate leuconostoc mesenteroides 11, was evaluated at 8oc and 15oc against listeria monocytogenes. the pathogen was inoculated in a crude preparation of the bacteriocin and its population was enumerated after 0.5 and 10 days. the title of the bacteriocin in the preparation was determined immediately before inoculation and after 10 days of incubation at both temperatures. as a negative control, a non-bacteriocin producing strain, leuconostoc mesenteroides a13, was used. bacteriocin of l. mesenteroides 11 partially inhibited l. monocytogenes at 8oc, but at 15oc it was unable to prevent growth of the pathogen. our findings suggest that the use of the semi-purified bacteriocin of l. mesenteroides 11 probably will not be suitable as a single hurdle to prevent l. monocytogenes growth in foods.
Chemical Fingerprinting of Counterfeits of Viagra and Cialis Tablets and Analogues via Electrospray Ionization Mass Spectrometry  [PDF]
Rafael S. Ortiz, Kristiane de Cássia Mariotti, Wanderson Rom？o, Marcos N. Eberlin, Renata P. Limberger, Paulo Mayorga
American Journal of Analytical Chemistry (AJAC) , 2011, DOI: 10.4236/ajac.2011.28106
Abstract: Direct infusion electrospray ionization mass spectrometry (ESI-MS) is shown to provide an efficient tech- nique for the investigation of polar composition of forensic tablets for male erectile dysfunction. ESI-MS fingerprinting of 41 commercial sildenafil samples (Viagra®, Cialis®, Lazar®, Libiden®, , Maxfil®, , Plenovit®, Potent 75®, Rigix®, V-50®, Vimax®, Pramil 75® and Pramil®) and 56 counterfeit samples (Viagra and Cialis) were obtained. The spectra for the authentic Viagra® tablets showed abundant ions exclusively corresponding to the sildenafil (SLD) molecule: [SLD + H]+ of m/z 475; [SLD + Na]+ of m/z 497; and [2SLD + H]+ of m/z 949. The spectra for com-mercial sildenafil samples also showed predominat SLD ions. Tablets of authentic Cialis® showed mainly ions of m/z 343, 365 and 707 from the lactose molecule (the excipient); as well as a minor ion of m/z 390 corresponding to the active ingredient tadalafil (TAD) in its protonated form [TAD + H]+. For counterfeit Cialis samples, how-ever, normally TAD ions of much high abundances was observed, together with ions corresponding to sildenafil analogues such as those of m/z 489 (homosildenafil) and 505 (hydroxyhomosildenafil). Principal component analysis was applied to ESI-MS fingerprint data, placing samples according to their contents of active ingredients hence authentic and counterfeit samples are easily recognized.
Roughness Control of Layer-by-Layer and Alternative Spray Films from Congo Red and PAH via Laser Light Irradiation  [PDF]
Gleidson Cardoso, Romário J. da Silva, Rafael R. G. Maciel, Nara C. de Souza, Josmary R. Silva
Materials Sciences and Applications (MSA) , 2012, DOI: 10.4236/msa.2012.38078
Abstract: Films from congo red (CR) alternated with poly(allylamine hydrochloride), PAH, were prepared by layer-by-layer and alternative spray techniques. In order to investigate the change of roughness induced by laser light irradiation (532 nm), both kinds of films were characterized by using UV-visible spectroscopy and atomic force microscopy (AFM). At dif- ferent irradiation times, layer-by-layer, LbL, films showed small changes in the roughness and irregular behavior, whereas spray films exhibited higher and a regular decreasing of roughness with increasing irradiation time. The higher roughness of spray films as compared with the LbL ones was attributed to different formation mechanisms of the films. The decreasing of the roughness as a function of the irradiation time (exhibited by the spray films) was associated to surface relaxation due to the interplay between photoisomerization of congo red dye and the heating of the sample during the laser light irradiation. The results suggested that the alternative spray technique is the best choose to control of roughness of the films by using light irradiation.
Realidade virtual no tratamento do transtorno de panico
Carvalho, Marcele Regine de;Freire, Rafael C.;Nardi, Antonio Egidio;
Jornal Brasileiro de Psiquiatria , 2008, DOI: 10.1590/S0047-20852008000100012
Abstract: virtual reality (vr) is a valuable tool in exposure treatment of panic disorder (pd). in virtual environments the patients experience similar physiological, psychic and somatic changes as in real life situations facilitating the habituation process. objective: we intend to divulge the current panorama of vr in treatment of pd. method: the literature on vr treatment for pd was revised with a systematic methodology in the pubmed database, using the keywords: virtual reality and panic disorder. results: virtual exposure treatment of pd usually shows good results and a great patient acceptability. only a few studies measure physiological responses during the exposure despite the importance of these data for evaluation of the treatment effectiveness. conclusions: although the vr treatment for pd usefulness is clear in the trials, a lack of controlled studies and standardized treatment protocols are verified.
The reaction of (R)-limonene with S-thioacids
Mattos, Marcio C. S. de;Bernini, Rafael Berrelho;
Journal of the Brazilian Chemical Society , 2007, DOI: 10.1590/S0103-50532007000500029
Abstract: the reaction of (r)-limonene with equimolar amount of s-thioacetic or s-thiobenzoic acids in refluxing toluene proceeded regioselectively in anti-markovnikoff fashion forming 9-[(4r, 8rs)-p-menthenyl] s-thiocarboxylates (71 and 61% yield, respectively). the montmorillonite k-10 clay-catalyzed reaction of (r)-limonene with s-thioacetic acid led to the s-thioester (65%) along with p-menthadienes and p-cymene. it was observed that k-10 clay promoted the isomerization of limonene to p-menthadienes and further disproportionation to p-cymene.
Verificación de métodos en un laboratorio acreditado y planificación del control de calidad interno Verifica o de métodos num laboratório credenciado e planejamento do controle de qualidade interno Method verification in a certified laboratory and internal quality control planification
Ricardo Guglielmone,Rafael de Elías,Oscar Kiener,César Collino
Acta bioqu？-mica cl？-nica latinoamericana , 2011,
Abstract: En el proceso de verificación de métodos se obtienen datos del desempe o del sistema de medición en las condiciones de trabajo del laboratorio; luego esto es cotejado con las especificaciones brindadas por el fabricante de reactivos y con los requerimientos de calidad disponibles de distintas fuentes. Los objetivos del presente trabajo fueron aplicar protocolos de evaluación de métodos publicados en guías internacionales (CLSI, Clinical Laboratory Standard Institute) para verificar el correcto rendimiento de las metodologías evaluadas y dise ar e implementar una estrategia de control de calidad interno (CCI) que permita evaluar la estabilidad del sistema de medición en el tiempo. Se evaluaron glucosa, creatinina y láctico deshidrogenasa (LDH); sobre las metodologías para la valoración de los mismos se realizaron los ensayos correspondientes a la verificación de precisión y veracidad, linealidad, límite de detección, comparación de equipos y establecimiento de valores de referencia de acuerdo con lo establecido en las guías CLSI EP15-A2, EP6-A, EP17-A, EP9-A2, C28-A2, respectivamente. En todos los ensayos realizados se cumplieron con las especificaciones estipuladas por el fabricante para cada analito, como así también con los requerimientos de calidad elegidos para el error total permitido. Además, se determinó el punto operativo y se especificaron las reglas de CCI adecuadas para el seguimiento del desempe o de estas metodologías. Con los resultados obtenidos se construyó una matriz de calidad para hacer el seguimiento mensual de los parámetros evaluados. Aplicando procedimientos de verificación de métodos se demostró la aceptabilidad de los parámetros analíticos evaluados. La verificación de los métodos permite dise ar y aplicar una estrategia de CCI para evaluar la estabilidad analítica de los sistemas de medición en el tiempo, dentro de un marco de seguridad analítica exigido para métodos acreditados. No processo de verifica o de métodos s o obtidos dados do desempenho do sistema de medi o nas condi es de trabalho do laboratório; depois isto é comparado com as especifica es oferecidas pelo fabricante de reagentes de laboratório e com os requerimentos de qualidade disponíveis em diversas fontes. Os objetivos do presente trabalho foram aplicar protocolos de avalia o de métodos publicados em guias internacionais (CLSI, Clínical Laboratory Standard Institute) para verificar o correto rendimento das metodologias avaliadas e desenhar e implementar uma estratégia de controle de qualidade interno (CCI) que permita avaliar a estabilidade do sistema de me
Hemoglobinas anormales en la población neonatal de Costa Rica
Gabriela Abarca,Marta Navarrete,Rafael Trejos,Carlos de Céspedes
Revista de Biología Tropical , 2008,
Abstract: Se han analizado un total de 70 943 muestras de sangre total en papel filtro S&S 903 de neonatos de Costa Rica (octubre 2005 a Octubre 2006) con el fin de detectar variantes de hemoglobina mediante la técnica de isoelectroenfoque. Se detectaron 891 casos con alguna variante para una frecuencia de 1/79. Se clasifican 5 casos homocigotos para hemoglobina S (anemia drepanocítica o anemia falciforme) y un caso doble heterocigoto para SC. En este estudio se demuestra que las variantes fenotípicas de hemoglobina S como la C, se encuentran distribuidas por todo el país con algunas diferencias locales, razón por la cual es importante que la prevención de nuevos casos se realicé a través de nuestro Programa Nacional de Tamizaje de Hemoglobinas junto con un Programa Nacional interdisciplinario de Educación para el portador del rasgo (AS/AC) como, para el enfermo y su familia; al igual que la instauración de programas dirigidos a médicos generales y enfermeras en todas las regiones de salud del país, para asegurar consejo genético a portadores y enfermos, y a la vez, mejorar los sistemas de tratamiento a los pacientes para reducir la morbi -mortalidad. Abnormal haemoglobins in the newborn human population of Costa Rica. Hemoglobinopathies are hereditary autosomic recessive diseases. A total of 70 943 samples of whole blood collected by heel prick in filter paper (S&S 903) from throughout Costa Rica (October 2005-October 2006) were analyzed to detect variants of hemoglobin by the iso-electric focusing technique. Eight hundred ninety one cases presented some variant, for a frecuency of 1/79. Five cases are homozygous for hemoglobin S (sickle cell disease) and one shows the double heterozygous genotype SC. in this study the S and C variants of hemoglobin, although with some local differences, are widespread all over the country. Thus, the prevention of new cases is important through the testing of hemoglobin in the Costa Rican National Newborn Screening Program, together with a interdisciplinary National Program of Education for the disease and carrier status (AS/AC) for patients, families and medicar personnel. This is the basis for proper genetic counseling, to improve treatment and to reduce morbi-mortality. Rev. Biol. Trop. 56 (3): 995-1001. Epub 2008 September 30
Domains of analyticity of Lindstedt expansions of KAM tori in dissipative perturbations of Hamiltonian systems
Renato C. Calleja,Alessandra Celletti,Rafael de la Llave
Mathematics , 2015,
Abstract: Many problems in Physics are described by dynamical systems that are conformally symplectic (e.g., mechanical systems with a friction proportional to the velocity, variational problems with a small discount or thermostated systems). Conformally symplectic systems are characterized by the property that they transform a symplectic form into a multiple of itself. The limit of small dissipation, which is the object of the present study, is particularly interesting. We provide all details for maps, but we present also the modifications needed to obtain a direct proof for the case of differential equations. We consider a family of conformally symplectic maps $f_{\mu, \epsilon}$ defined on a $2d$-dimensional symplectic manifold $\mathcal M$ with exact symplectic form $\Omega$; we assume that $f_{\mu,\epsilon}$ satisfies $f_{\mu,\epsilon}^*\Omega=\lambda(\epsilon) \Omega$. We assume that the family depends on a $d$-dimensional parameter $\mu$ (called drift) and also on a small scalar parameter $\epsilon$. Furthermore, we assume that the conformal factor $\lambda$ depends on $\epsilon$, in such a way that for $\epsilon=0$ we have $\lambda(0)=1$ (the symplectic case). We study the domains of analyticity in $\epsilon$ near $\epsilon=0$ of perturbative expansions (Lindstedt series) of the parameterization of the quasi--periodic orbits of frequency $\omega$ (assumed to be Diophantine) and of the parameter $\mu$. Notice that this is a singular perturbation, since any friction (no matter how small) reduces the set of quasi-periodic solutions in the system. We prove that the Lindstedt series are analytic in a domain in the complex $\epsilon$ plane, which is obtained by taking from a ball centered at zero a sequence of smaller balls with center along smooth lines going through the origin. The radii of the excluded balls decrease faster than any power of the distance of the center to the origin.
A swirler stabilized combustion chamber for a micro-gas turbine fuelled with natural gas
Krieger, Guenther C.;Campos, André P. V. de;Sacomano Filho, Fernando L.;Souza, Rafael C. de;
Journal of the Brazilian Society of Mechanical Sciences and Engineering , 2012, DOI: 10.1590/S1678-58782012000400004
Abstract: micro-gas turbines are a good alternative for on-site power generation, since their operation is very reliable. the possibility of operating with various fuels increases versatility and, as a result, the usage of these devices. focusing on a performance improvement of a tri-fuel low-cost micro-gas turbine, this work presents investigations of the inner flow of its combustion chamber. the aim of this analysis was the characterization of the flame structure by the temperature field of the chamber inner flow. the chamber was fuelled with natural gas. in the current chamber, a swirler and a reversed flow configuration were utilized to provide flame stabilization. the inner flow investigations were done with numerical analysis, which were compared to experimental data. the analysis of the inner flow was done with numerical simulations, which used the rsm turbulence model. a β-pdf equilibrium model was adopted to account for the turbulent combustion process. different models of heat transfer were compared. thermal radiation and specially heat conduction in the liner walls played significant roles on results.
Evaluation of the Antimicrobial Activity of Stryphnodendron barbatiman against Citrobacter freundii  [PDF]
Nara C. de Souza, Marcio N. Gomes, Rafael R. G. Maciel, Romário J. da Silva, Tarquin F. Trescher, Filipe D. S. Gorza, Graciela C. Pedro, Kennedy C. S. Correa, Marcio C. R. Souza, Josmary R. Silva
Materials Sciences and Applications (MSA) , 2013, DOI: 10.4236/msa.2013.412099
Abstract:

Medicinal plants have been presented as a valuable source of preservation of human health. In special, Stryphnodendron barbatiman has been employed due to its antimicrobial activity. This plant is rich in tannins and has been used in popular medicine for the treatment of gastrointestinal disorder, treatment of lesions, and also as anti-inflammatory microbicide. Citrobacter freundii is a member of the family Enterobacteriaceae and is one of the major causes of opportunistic infections. This microorganism is a bacterium (bacillus) aerobic gram-negative with a length in the range of 1 to 5 mm. C. freundii is commonly found in water, soil, food and occasionally in the gastrointestinal tract of animals and humans. In this paper, we have demonstrated the antibacterial activity of S. barbatiman by observing cellular death by using inhibition halo approach. Atomic force microscopy and FT-IR spectroscopy results suggested that interaction between the main active components of S. barbatiman with cellular wall of C. freundii gives rise to cellular wall damage, and then leads this microorganism to death.

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