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Nomenclatura Unesco > (23) Química

Mostrando recursos 201 - 220 de 41,753

201. Santiago Ramón y Cajal sobre el problema de la conciencia - Currás Puente, Emilia; Wulff, Enrique
[EN] Santiago Ramón y Cajal (1852-1934) stressed the significance of the relation between the brain and the mind through the patterning of consciousness during brain development. There are levels of nervous activity and no real hint of Cajal identifying the language as a first structure. Cajal’s deductions on cerebral localization makes his research relevant to the doctrine of the seat of the soul. He viewed the integration of the intelligence and the emotions in the organ of consciousness by way of the innate brain’s architecture excellence. He engaged on pathological and physiological chemical researches to promote and improve the regeneration...

202. El sistema internacional -HACCP- en el actual derecho interno argentino - Novoa Farkas, María Luz Macarena
El programa de Análisis de Peligros y Puntos Críticos de Control conocido por su siglas HACCP, Hazar Análisis Critical Control Points,es un método de fiscalizacalización de productos caracterizado por presentar enfoques preventivos y sistemáticos, para eliminar o minimizar los peligros físicos, químicos y biológicos en los alimentos, constituyendo, en la actualidad, la mejor herramienta para el logro de la inocuidad alintaria. La implementación de este Sistema, mundialmente exigido contribuye a promover el comercio internacional de alimentos al mejorar la confianza de los compradores. Así es que por Resolución Conjunta 87/2008 - SPRI y 340/2008 –SAGPyA se Incorporo el articulo 18bis al...

203. Estudio palinológico de las especies andaluzas de la familia ranunculaceae - Fernández-González, Inmaculada
La familia Ranunculaceae, incluida actualmente en el orden Ranunculales (CRONQUIST, 1981), está compuesta por plantas terrestres o acuáticas, predominando las hierbas perennes con órganos caulinares subterráneos ... Esta familia muestra una amplia variación de estructuras florales debida a que sus representantes están adaptados a diversos sistemas de polinización (CRONQUIST, l. c.). Por ello sus flores generalmente hermafroditas y de tamaño muy variable, pueden ser actinomorfas o zigomorfas, y presentan sus piezas ordenadas helicoidal o cíclicamente. Su periantio es sencillo, sepaloideo o petaloideo, o doble. El androceo está integrado normalmente por numerosos estambres libres de maduración centrípeta, parte de ellos transformados en...

204. Estudio químico-sensorial de la composición no volátil de los vinos. Influencia de técnicas de aclareo en el perfil fenólico y organoléptico de los vinos - Gonzalo Diago, Ana

205. Separation of zinc and bismuth by facilitated transport through activated composite membranes - Macanàs de Benito, Jorge; Muraviev, Dmitri N.; Oleinikova, Maria; Muñoz Tapia, Maria
This paper reports the results on the further development of activated composite membranes (ACM) containing di-2-ethyhexyl-dithiophosphoric acid (D2EHDTPA) as a carrier. The selectivity and transport properties of D2EHDTPA based ACMs towards different metal ions including bismuth and zinc appear to be interconnected with each other. It has been shown that unlike the liquid-liquid extraction of bismuth, the use of D2EHDTPA-ACM permits to recover and to concentrate bismuth from a highly saline medium without irreversible destruction of the carrier. The difference in the rates of bismuth and zinc transport through ACMs permits their separation since the former is concentrated in the stripping solution...

206. Separation of zinc and bismuth by facilitated transport through activated composite membranes - Macanàs de Benito, Jorge; Muraviev, Dmitri N.; Oleinikova, Maria; Muñoz Tapia, Maria
This paper reports the results on the further development of activated composite membranes (ACM) containing di-2-ethyhexyl-dithiophosphoric acid (D2EHDTPA) as a carrier. The selectivity and transport properties of D2EHDTPA based ACMs towards different metal ions including bismuth and zinc appear to be interconnected with each other. It has been shown that unlike the liquid-liquid extraction of bismuth, the use of D2EHDTPA-ACM permits to recover and to concentrate bismuth from a highly saline medium without irreversible destruction of the carrier. The difference in the rates of bismuth and zinc transport through ACMs permits their separation since the former is concentrated in the stripping solution...

207. Zn(II), Cd(II) and Cu(II) separation through organic–inorganic Hybrid Membranes containing di-(2-ethylhexyl) phosphoric acid or di-(2-ethylhexyl) dithiophosphoric acid as a carrier - Resina Gallego, Montserrat; Macanàs de Benito, Jorge; de Gyves Marciniak, Josefina; Muñoz Tapia, Maria
A membrane process for metal recovery from aqueous solutions was studied. Metal ions diffused from the feed solution to the stripping phase through an Hybrid Membrane containing di-(2-ethylhexyl) phosphoric acid (D2EHPA) and/or di-(2-ethylhexyl) dithiophosphoric acid (D2EHDTPA) as a carrier. Such membranes were prepared by a sol–gel route including cellulose triacetate and polysiloxanes. Transport behaviour was evaluated for both carriers under similar experimental conditions. The transport experiments reported here concerned transport at different cycles and selectivity towards different metal ions. Using D2EHPA the membrane provided a selective transport of zinc to the stripping compartment of the membrane cell, while copper and...

208. Zn(II), Cd(II) and Cu(II) separation through organic–inorganic Hybrid Membranes containing di-(2-ethylhexyl) phosphoric acid or di-(2-ethylhexyl) dithiophosphoric acid as a carrier - Resina Gallego, Montserrat; Macanàs de Benito, Jorge; de Gyves Marciniak, Josefina; Muñoz Tapia, Maria
A membrane process for metal recovery from aqueous solutions was studied. Metal ions diffused from the feed solution to the stripping phase through an Hybrid Membrane containing di-(2-ethylhexyl) phosphoric acid (D2EHPA) and/or di-(2-ethylhexyl) dithiophosphoric acid (D2EHDTPA) as a carrier. Such membranes were prepared by a sol–gel route including cellulose triacetate and polysiloxanes. Transport behaviour was evaluated for both carriers under similar experimental conditions. The transport experiments reported here concerned transport at different cycles and selectivity towards different metal ions. Using D2EHPA the membrane provided a selective transport of zinc to the stripping compartment of the membrane cell, while copper and...

209. Electrophoresis and stability of nano-colloids: History, theory and experimental examples - Felix, C.; Yaroshchuk, Andriy; Pasupathi, S.; Pollet, B. G.; Bondarenko, M.P.; Kovalchuk, V.I.; Zholkovskij, Emiliy K.
The paper contains an extended historical overview of research activities focused on determining interfacial potential and charge of dispersed particles from electrophoretic and coagulation dynamic measurements. Particular attention is paid to nano-suspensions for which application of Standard Electrokinetic Model (SEM) to analysis of experimental data encounters difficulties, especially, when the solutions contain more than two ions, the particle charge depends on the solution composition and zeta-potentials are high. Detailed statements of Standard Electrokinetic and DLVO Models are given in the forms that are capable of addressing electrophoresis and interaction of particles for arbitrary ratios of the particle to Debye radius,...

210. Electrophoresis and stability of nano-colloids: History, theory and experimental examples - Felix, C.; Yaroshchuk, Andriy; Pasupathi, S.; Pollet, B. G.; Bondarenko, M.P.; Kovalchuk, V.I.; Zholkovskij, Emiliy K.
The paper contains an extended historical overview of research activities focused on determining interfacial potential and charge of dispersed particles from electrophoretic and coagulation dynamic measurements. Particular attention is paid to nano-suspensions for which application of Standard Electrokinetic Model (SEM) to analysis of experimental data encounters difficulties, especially, when the solutions contain more than two ions, the particle charge depends on the solution composition and zeta-potentials are high. Detailed statements of Standard Electrokinetic and DLVO Models are given in the forms that are capable of addressing electrophoresis and interaction of particles for arbitrary ratios of the particle to Debye radius,...

211. Electrocatalytic production of hydrogen boosted by organic pollutants and visible light - Soler Turu, Lluis; Macanàs de Benito, Jorge; Muñoz Tapia, Maria; Casado Giménez, Juan
A new method to produce high-purity hydrogen using photoelectrocatalytic reactions is studied. This integrated process uses solar energy and the Gibbs free energy of oxidation of organic wastes to help reducing the energy consumption of water electrolysis. The method diminishes the thermodynamic potential to 0.77 V and practical voltages to ca. 1.2 V, due to an electrocatalytic reaction in the presence of iron ions. The anolyte is illuminated, and separated from the catholyte by a proton exchange membrane. The process oxidizes water pollutants and avoids the anodic corrosion of a stainless steel anode, but not every sacrificial substance has a...

212. Electrocatalytic production of hydrogen boosted by organic pollutants and visible light - Soler Turu, Lluis; Macanàs de Benito, Jorge; Muñoz Tapia, Maria; Casado Giménez, Juan
A new method to produce high-purity hydrogen using photoelectrocatalytic reactions is studied. This integrated process uses solar energy and the Gibbs free energy of oxidation of organic wastes to help reducing the energy consumption of water electrolysis. The method diminishes the thermodynamic potential to 0.77 V and practical voltages to ca. 1.2 V, due to an electrocatalytic reaction in the presence of iron ions. The anolyte is illuminated, and separated from the catholyte by a proton exchange membrane. The process oxidizes water pollutants and avoids the anodic corrosion of a stainless steel anode, but not every sacrificial substance has a...

213. Estudio comparativo de la composición química de los aceites esenciales de aloysia triphylla l´her britton cultivada en diferentes regiones de colombia. - Stashenko, Elena; Martínez, Jairo René; Durán G., Diego Camilo; Díaz, Olga Liliana
Essential oils were obtained with microwave-assisted hydrodistillation from Aloysia triphylla plants collected at three stages of development in three different regions of Colombia. Their composition was determined by GC-MS (EI, 70 eV). The main component in all oils was citral (32-41%). The highest oil yield was obtained from plants collected in Bolívar, Santander (0.88%). Plants with 2 months of development and before flowering, showed the largest content of metabolites of interest

214. Determinación mediante hs-spme/gc-ms, de la composición química de la fragancia y el absoluto de las flores de posoqueria latifolia. - Martínez Morales, Jairo; Stashenko, Elena; Ariza, Oscar Augusto; Rueda Parra, Elkin Darío; Archila, Johanna Andrea
The chemical compositions of the absolute and the fragrance of the flowers of Posoqueria latifolia were determined by GC-MS (EI, 70 eV) . The fragrance was sampled in vivo by means of HS-SPME. The compounds found in the fragrance were (Z)-3-hexenyl acetate (80.7%) and hexyl acetate (5.8%). The absolute was obtained from the concrete of the flowers by means of ethanolic extraction at 38 ºC. The main compounds found in the absolute were 1-pentacosane (26.2%), benzyl salicylate (7.4%), tricosane (5.9), linolenic acid (4.8%), pentacosane (4.5%), benzyl benzoate (3.3%) and eugenol (2.8%).

215. Estudio quimico y obtencion de principios activos de la especie rollinia pittieri (annonaceae) del alto sinu. - Torres, Omar; Angulo Ortiz, Alberto; Santafe Patiño, Gilmar; Saez Vega, Jairo; Alberto Rojano, Benjamín; Villa, Hiltony; Montaño, Mary; Galeano, Paula
From the etanolic extract of the leaves, bark and wood of the Rollinia Pittieri ( Annonaceae) were isolated and identified five alkaloids with aporphine nucleus: Anonaine 1, Nornuciferine 2, O-methilmoschatoline 3, Isomoschatoline 4 and Liriodenine 5; two flavoniods: 5,7,3´,4´-tetrahidroxi-3- O-rhamnosil-2-phenilcromone 6, 5,7,4´-tetrahidroxi-3-O-rhamnosil-2- phenilcromone 7. All compounds were identified by spectroscopic methods (IR, UV MS, 1H NMR and 13C NMR,), including 2D techniques and by comparison with dates reported spectroscopic in the literature. The compound 7 showed a significant activity catcher of free radicals according to the DPPH, ABTS and Enzimatic Generation of Superoxid Anion essays.

216. Tamizaje fitoquimico y actividad antioxidante de extractos acuoso y orgánicos de justicia pectoralis jacq. (amansa toros) y de volátiles y no volátiles de lippia alba mill. (pronto alivio) cultivadas en diferentes pisos térmicos.
El uso de Justicia pectoralis Jacq. y Lippia alba Mill en la cultura popular colombiana en el tratamiento de diferentes enfermedades y su escaso conocimiento y aplicabilidad en la región tolimense, motivó el estudio de estas especies vegetales a fin de determinar el efecto del cambio altitudinal en la actividad antioxidante de los extractos acuoso y orgánicos de J. pectoralis y de los volátiles y no volátiles de L. alba. Las diferencias de altitud no modifican la proporción relativa de los constituyentes químicos, lo que a su vez no influye en la actividad antioxidante de estas especies.

217. Azafluorenonas en corteza de oxandra longipetala r. e. fr. (annonaceae). - Angulo Ortiz, Alberto; Cuca Suarez, Luis E.; Santafe Patiño, Gilmar; Torres, Omar
El estudio químico del extracto de alcaloides totales, realizado por el método clásico, de la corteza de Oxandra longipetala R. E. Fr., colectada en el departamento de Córdoba, Colombia, permitió el aislamiento e identificación de cuatro alcaloides de tipo azafluorenona: ursulina, isoursulina, O-metilmacondina y macondina, junto con las oxoaporfinas lysicamina, O-metilmoschatolina, y liriodenina. Las estructuras fueron elucidadas por métodos espectroscópicos (UV, IR, RMN-1H, RMN-13C, experimentos 2D, espectrometría de masas) y por comparación con datos de la literatura.

218. Estudio de la composición química y la actividad biológica de los aceites esenciales de diez plantas aromáticas colombianas. - Martínez, Jairo René; Stashenko, Elena; Castañeda, Martha I.; Muñoz, Amner
En este estudio se determinó la composición química de los aceites esenciales (AEs) de las hojas de 10 plantas aromáticas colombianas. Los AEs se aislaron empleando la técnica de hidrodestilación asistida por la radiación de microondas (MWHD) y la identificación de los componentes de los AEs se realizó mediante el análisis por cromatografía de gases � espectrometría de masas (GC-MS), utilizando dos columnas (DB-5 y DB-Wax). La identificación de los compuestos se basó en los índices de Kovàts y en la comparación de los espectros de masas con los de las bases de datos QuadLib2004, NIST 2002, Wiley 138k.

219. Composición química del aceite esencial de hojas y tallos de bursera graveolens (burseraceae) de colombia. - Leyva, Miguel Antonio; Martínez, Jairo René; Stashenko, Elena
The essential oils of leaves and stems of Bursera graveolens (Burseraceae family), were obtained using microwave-assisted hydrodistillation (MWHD) and analyzed by gas chromatography-mass spectrometry (EI, 70 eV). The main components found in the oil of leaves were: limonene (48.3%), caryophyllene oxide (13.6%) and trans-caryophyllene (8.1%). The essential oil of stems showed a higher content of limonene (42.1%), myrcene (19.8%) and menthofuran (14.7). The components Z-b-ocymene (14.3%) and menthofuran present in the oil of stems, were not found in the essential oil of leaves.

220. Química y actividad biologica de chromolaena perglabra. - Rodriguez, Oscar E.; Torrenegra G., Rubén D.
Esta investigación se encaminó a determinar los metabolitos secundarios presentes en hojas y tallos de la especie: Chromolaena perglabra (B. L. Robinson) King & H. Rob., colectada en Tinjacá (Boyacá � Colombia). Se estableció la actividad antiprotozoaria (leishmaniosis y chagas.) y toxicidad. Los resultados de este trabajo suministraron herramientas para validar el uso de esta especie considerada maleza. Se encontró actividad significativa in Vitro contra agentes causantes de chagas y leishmaniosis en algunos extractos y fracciones. Se identificaron esteroides y flavonoides; se estableció de manera preliminar la toxicidad para reconocer parte de los riesgos inherentes a su uso.

 

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