Sample records for CRISTALES LIQUIDOS (liquid crystals)
from WorldWideScience.org

Sample records 1 - 20 shown. Select sample records:



1

Transiciones de fase topológicas en cristales líquidos

Paredes, R; Fariñas-Sánchez, A.I; Berche, B
2006-05-01

Resumen en español Mediante simulaciones de Monte Carlo, utilizando escalamiento de tamaño finito y transformaciones conformes se reportan evidencias de una transición de fase topológica en cristales líquidos en dos dimensiones. A altas temperaturas se presenta una fase paramagnética, mientras que a bajas temperaturas se encuentra un fase de cuasi-largo-orden (QLRO). Se encuentra que a muy bajas temperaturas el exponente de la función de correlación de la fase QLRO es lineal con la t (mas) emperatura, teniéndose de esta manera un comportamiento típico de ondas de espín. Esto último contradice predicciones de que para sistemas con grupo de simetría global no abeliano las ondas de espín no son relevantes. Adicionalmente se discute que implicaciones tendría la presencia de impurezas en este tipo de transiciones. Resumen en inglés By means of Monte Carlo simulations, using finite size scaling and conformal transformations, evidences of a topological phase transition in liquid crystals in two dimensions are reported. A paramagnetic phase appears at high temperature whereas a quasi-long-range-order (QLRO) phase is founded at low temperatures. It is determined that the correlation function exponent, at very low temperatures, is linear with the temperature, a typical behavior of spin waves. This contra (mas) dicts predictions that for systems with non-abelian group of global symmetry the spin waves are not relevant. Aditionally, the implications that would have the presence of impurities in this type of transitions is discussed.

Scientific Electronic Library Online (Spanish)

2

Análisis del comportamiento presión-temperatura y otras propiedades termodinámicas para los cristales líquidos PAA, 5CB y HOAOB utilizando el modelo convex peg y la teoría de los funcionales de la densidad en la transición isótropa-nemático

García-Sánchez, E; Mendoza-Huizar, L.H.; Álvarez Lozano, J; Rentaría Muñoz, C; Flores Gómez, M.Á.
2007-06-01

Resumen en español En este trabajo utilizamos la teoría de los funcionales de la densidad para determinar las propiedades termodinámicas de las fases isótropa y nemática de los cristales líquidos, basados en el modelo Convex Peg. La energía libre de Helmholtz del sistema molecular, una coraza dura circunscrita por un potencial tipo pozo cuadrado esférico (SW), es obtenida de una teoría de perturbaciones a segundo orden para partículas no esféricas SW, combinadas con la aproximaci� (mas) �n de desacoplamiento de Parsons de los grados de libertad traslacionales y rotacionales, y una aproximación de largo alcance para la evaluación de los términos de perturbación. La teoría es aplicada para predecir el diagrama de fase y la transición isótropa-nemática del p-azoxianisol (PAA), 4 - pentyl - 4' - cyanobiphenyl (5CB) y el 4 - 4'- bis (heptiloxy) azoxybenzene (HOAOB). Para hacer esto fueron derivadas una estimación del volumen y k del cristal líquido utilizando calculos IPCM; el volumen obtenido es mapeado al volumen de un elipsoide de revolución rígido de una molécula Convex Peg. Un muy buen acuerdo es obtenido en la predicción de las propiedades termodinámicas cuando son comparadas con los datos experimentales. Resumen en inglés In this work, we employed the Density Functional Theory to determine thermodynamic properties of isotropic and nematic phases of liquid crystals, based on a "Convex Peg" model. The Helmholtz-free energy of the molecular system, a convex hard core within an encircling spherical square-well (SW) potential, is obtained from a second-order perturbation theory for SW nonspherical particles, combined with the Parsons decoupling approximation of the translational and rotational (mas) degrees of freedom, and a long-range approximation for the evaluation of the perturbation terms. The theory is applied to predict the phase diagram and isotropic-nematic transition of p-azoxyanisole (PAA), 4 -pentyl - 4' - cyanobiphenyl (5CB) and 4 - 4'- bis (heptiloxy) azoxybenzene (HOAOB). To do this, an estimation of the volume and k of a Liquid Crystal molecule was derived using IPCM calculations; the volume obtained is mapped into a hard ellipsoid revolution volume of a Convex Peg molecule. A very good agreement in the prediction of the thermodynamic properties is obtained when they are compared with experimental data.

Scientific Electronic Library Online (Spanish)

3

X-ray diffraction analysis of internal wool lipids

Fonollosa Argemi, Jordi; Campos, Lourdes; Martí Gelabert, Meritxell; Maza, Alfons de la; Parra Juez, José Luis; Coderch Negra, M. Luisa
2004-05-06

Digital.CSIC (Spain)

4

X-cut quartz crystal impedance meter for liquid characterization

Resa, Pablo; Sierra, Carlos; Elvira, Luis
2011-02-01

Digital.CSIC (Spain)

6

Wide temperature range mesomorphic behaviour of highly fluorinated 15-membered macrocycles and their open trisulphonamide precursor.

Soler, R.; Badetti, E.; Moreno-Maas, M.; Vallribera, A.; Sebastin, R. M.; Vera, Francisco; Serrano, José Luis; Sierra, Teresa
2007-02-01

Digital.CSIC (Spain)

8
9

Thermodynamics of thallium alkanoates V. Heat capacity and thermodynamic functions of thallium(I) n-decanoate from 6 to 480 K

López de la Fuente, F. L.; Rodríguez Cheda, José A.; Fernández Martín, Fernando; Westrum, Edgar F.
1988-10-01

Digital.CSIC (Spain)

10

Thermodynamics of thallium alkanoates III. Heat capacity and thermodynamic functions of thallium(I) n-tetradecanoate from 7 to 450 K

Ngeyi, Stanley P.; Westrum, Edgar F.; López de la Fuente, F. L.; Rodríguez Cheda, José A.; Fernández Martín, Fernando
1987-03-01

Digital.CSIC (Spain)

12

Theory and simulation of the confined Lebwohl-Lasher model

Marguta, Ramona G.; Martínez-Ratón, Yuri; Almarza, Noé G.; Velasco, Enrique
2011-04-05

Digital.CSIC (Spain)

13

The imaging magnetograph eXperiment for the SUNRISE balloon Antarctica project

Martínez Pillet, Valentín; Bonet, José A.; Collados, Manuel V.; Jochum, Lieselotte; Mathew, S.; Medina Trujillo, J. L.; Ruiz Cobo, B.; Toro, José Carlos del; López Jiménez, A. C.; Castillo Lorenzo, José Luis; Herranz, Miguel; Jerónimo, José María; Mellado, Pablo; Morales, Rafael; Rodríguez, Julio; Álvarez-Herrero, Alberto; Belenguer, Tomás; Heredero, R. L.; Menéndez, M.; Ramos, G.; Reina, Manuel; Pastor, C.; Sánchez, A.; Villanueva, J.
2004-10-20

Digital.CSIC (Spain)

14

The effect of molecular shape on the thermotropic liquid crystal behavior of monolauroylated amino acid glyceride conjugates

Morán, María del Carmen; Pinazo Gassol, Aurora; Clapés Saborit, Pere; Infante, María Rosa; Pons Pons, Ramón
2005-11-05

Digital.CSIC (Spain)

15

The effect of molecular shape on the thermotropic liquid crystal behavior of monolauroylated amino acid glyceride conjugates

Morán, María del Carmen; Pinazo Gassol, Aurora; Clapés Saborit, Pere; Infante, María Rosa; Pons Pons, Ramón
2005-11-05

Digital.CSIC (Spain)

16

The dynamics of nacre

H. E. Cartwright, Julyan; G Checa, Antonio
2007-06-01

Digital.CSIC (Spain)

17

The association of DNA and stable catanionic amino acid-based vesicles

Rosa, Mónica; Morán, María del Carmen; Miguel, Maria da Graça; Lindman, Björn
2007-01-13

Digital.CSIC (Spain)

18

The Absorption of Sound in Suspensions Due to the Acoustic Wake Effect

González Gómez, Icíar; Gallego Juárez, Juan Antonio

Communication presented at the 17th International Congress on Acoustics, Rome, 2-7 September 2001. | The absorption of sound in suspensions with particles much smaller than the acoustic wavelength is mainly due to the viscous drag between the fluid and the particles. In addition, viscous asymmetries...

DRIVER (Spanish)

19

The Absorption of Sound in Suspensions Due to the Acoustic Wake Effect

González Gómez, Icíar; Gallego Juárez, Juan Antonio
2001-09-01

Digital.CSIC (Spain)

21

Synthesis and properties of 2-phenylbenzoxazole-based luminophores for insitu photopolymerized liquid-crystal films

Giménez, Raquel; Oriol, Luis; Piñol, Milagros; Serrano, José Luis; Viñuales, Ana I.; Fisher, Thomas; Stumpe, Joachim
2006-02-21

Digital.CSIC (Spain)

23

Supramolecular structures and columnar mesophase induction in nondiscoid pyrazoles by complexation to rhodium(I)

Giménez, Raquel; Elduque, Anabel; López, José A.; Barberá, Joaquín; Cavero, Emma; Lantero, Ignacio; Oro, Luis A.; Serrano, José Luis
2006-11-15

Digital.CSIC (Spain)

24

Structural study of a bent-core liquid crystal showing the B1-B2 transition

Folcia, César L.; Etxebarria, Jesús; Ortega, Josu; Ros, M. Blanca
2006-09-01

Digital.CSIC (Spain)

25

Stabilization of Paraffin Emulsions Used in the Manufacture of Chipboard Panels by Liquid Crystalline Phases

Mújika-Garai, R.; Aguilar-García, C.; Juárez-Arroyo, F.; Covián-Sánchez, I.; Nolla, J.; Esquena, Jordi; Solans, Conxita; Rodríguez-Valverde, M. A.; Tejera-García, R.; Cabrerizo-Vílchez, M. A.; Hidalgo-Álvarez, R.
2007-08-01

Digital.CSIC (Spain)

27

Spiral and target patterns in bivalve nacre manifest a natural excitable medium from layer growth of a biological liquid crystal

Cartwright, Julyan H. E.; Checa, Antonio G.; Escribano, Bruno; Sainz-Díaz, C. Ignacio
2009-06-15

Digital.CSIC (Spain)

28

Simulation study of the phase behavior of a planar Maier-Saupe nematogenic liquid

Lomba, Enrique; Martín, Claudio; Almarza, Noé G.; Lado, Fred
2005-04-22

Digital.CSIC (Spain)

29

Self-assembled bent-core side-chain liquid crystalline polymers

Barberá, Joaquín; Gimeno, Nélida; Pintre, Inmaculada C.; Ros, M. Blanca; Serrano, José Luis
2006-01-30

Digital.CSIC (Spain)

30

Room temperature mechanical properties of high alumina refractory castables with spinel, periclase and dolomite additions

Díaz, Luis Antonio; Torrecillas San Millán, Ramón; Simonin, F.; Fantozzi, Gilbert
2008-06-09

Digital.CSIC (Spain)

31

Roof-shaped pyrazaboles as a structural motif for bent-core liquid crystals

Cavero, Emma; Lydon, Donocadh P.; Uriel, Santiago; Fuente, M. Rosario de la; Serrano, José Luis; Giménez, Raquel
2007-05-01

Digital.CSIC (Spain)

32

Propeller-like hydrogen-bonded banana - melamine complexes inducing helical supramolecular organizations

Barberá, Joaquín; Puig, Laura; Romero, Pilar; Serrano, José Luis; Sierra, Teresa
2006-03-15

Digital.CSIC (Spain)

33

Procedure for preparation of thin sheets of collodial crystal, and product thus obtained

Cervelló, Antonio Agustín; Ocaña Jurado, Manuel; Míguez García, Hernán Ruy
2007-12-13

Digital.CSIC (Spain)

34

Polyazomethine/carbon nanotube composites

Lafuente, Esperanza; Piñol, Milagros; Oriol, Luis; Muñoz, Edgar; Benito, Ana M; Maser, Wolfgang K; Dalton, A. B.; Serrano, José Luis; Martinez, M. Teresa
2006-07-01

Digital.CSIC (Spain)

35

Photosensitive Ionic Nematic Liquid Cristalline Complexes Based on Dendrimers and Hyperbranched Polymers and a Cyanoazobenzene Carboxylic Acid

Marcos, Mercedes; Alcalá, Rafael; Barberá, Joaquín; Romero, Pilar; Sánchez, Carlos; Serrano, José Luis
2008-05-27

Digital.CSIC (Spain)

36

Photoinduced supramolecular chirality in side-chain liquid crystalline azopolymers

Tejedor, Rosa M.; Millaruelo, Marta; Oriol, Luis; Serrano, José Luis; Alcalá, Rafael; Rodríguez, Francisco J.; Villacampa, Belén
2006-03-01

Digital.CSIC (Spain)

37

Photoinduced Chiral Nematic Organization in an Achiral Glassy Nematic Azopolymer.

Tejedor, Rosa M.; Oriol, Luis; Serrano, José Luis; Partal Ureña, F.; López González, J. J.
2007-10-31

Digital.CSIC (Spain)

39

Phase behavior of the confined Lebwohl-Lasher model

Almarza, Noé G.; Martín, Claudio; Lomba, Enrique
2010-07-28

Digital.CSIC (Spain)

40

Phase behavior of the Confined Lebwohl-Lasher Model

Almarza, Noé G.; Martín, C.; Lomba, E.
2010-01-01

Digital.CSIC (Spain)

41

Phase behavior of a hard sphere Maier-Saupe nematogenic system in three dimensions

Lomba, Enrique; Martín, Claudio; Almarza, Noé G.; Lado, Fred
2006-08-04

Digital.CSIC (Spain)

42

Phase behavior and preparation of mesoporous silica in aqueous mixtures of fluorinated surfactant and hydrophobic fluorinated polymer

Sharma, Suraj Chandra; Kunieda, Hironobu; Esquena, Jordi; Rodríguez Abreu, Carlos

8 pages, 10 figures. | The phase behavior and formation of self-assemblies in the ternary water/fluorinated surfactant (C8F17EO10)/hydrophobic fluorinated polymer (C3F6O)nCOOH system and the application of those assemblies in the preparation of mesostructured silica have been investigated by means o...

DRIVER (Spanish)

44

PAMAM- and DAB-derived dendromesogens: The plastic supermolecules

Rueff, Jean-Michel; Barberá, Joaquín; Marcos, Mercedes; Omenat, Ana; Martín-Rapún, Rafael; Donnio, Bertrand; Guillon, Daniel; Serrano, José Luis
2005-12-01

Digital.CSIC (Spain)

45

Optimization of nano-emulsion preparation by low-energy methods in an ionic surfactant system

Solé, Isabel; Maestro, Alicia; González Azón, Carmen; Solans, Conxita; Gutiérrez, José M.
2006-08-31

Digital.CSIC (Spain)

46

Oil/water droplet formation by temperature change in the water/c(16)e(6)/mineral oil system

Morales, D.; Solans, Conxita; Gutiérrez, José M.; García-Celma, M. J.; Olsson, U.
2006-02-28

Digital.CSIC (Spain)

47

Novel mesogenic asymmetric diacylhydrazines: synthesis, mesomorphic behaviour and X-ray study.

Parra, M.; Hidalgo, P.; Barberá, Joaquín; Carrasco, E.; Saavedra, C.
2006-04-01

Digital.CSIC (Spain)

48

New 1,2,4- and 1,3,4-oxadiazole materials: synthesis, and mesomorphic and luminescence properties.

Parra, M.; Hidalgo, P.; Carrasco, E.; Barberá, Joaquín; Silvino, L.
2006-08-01

Digital.CSIC (Spain)

49

Nano-emulsions preparation by low energy methods in an ionic surfactant system

Solè, Isabel; Maestro, Alicia; Pey, C. M.; González, Carmen; Solans, Conxita; Gutiérrez, José M.

6 pages, 1 table, 9 figures.-- Printed version published Oct 5, 2006.-- Issue title: Papers from "Formula IV: Frontiers in Formulation Science", an International conference organised by the RSC, held in London, July 4-7th 2005. | The emulsion inversion point method was used to form nano-emulsions in...

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50

Nano-emulsions preparation by low energy methods in an ionic surfactant system

Solé, Isabel; Maestro, Alicia; Pey, C. M.; González Azón, Carmen; Solans, Conxita; Gutiérrez, José M.
2006-03-06

Digital.CSIC (Spain)

51

NMR Relaxation study of molecular dynamics in the smectic a phase of PAMAM liquid crystalline dendrimers of generation 1 and 3

Van-Quynh, A.; Filip, Daniela; Cruz, C.; Sebastiáo, P. J.; Ribeiro, A. C.; Rueff, Jean-Michel; Marcos, Mercedes; Serrano, José Luis
2006-07-01

Digital.CSIC (Spain)

55

Migration and accumulation of ultra-depleted subduction-related melts in the Massif du Sud ophiolite

Garrido, C. J.; Marchesi, Claudio; Godard, Marguerite; Belley, France; Ferré, Eric
2009-06-01

Digital.CSIC (Spain)

56

Low-cost liquid crystal display optimized as a monopixel coherent modulator

Márquez Ruiz, Andrés; Álvarez López, Mariela Lázara; Puerta, Luis A.; Estévez, Rocío; Fernández Varó, Elena; Beléndez Vázquez, Augusto

We propose the use of low cost alphanumeric liquid crystal displays (LCD) not only as an educational tool, to introduce students the insights of the electrooptic performance of liquid crystals, but also as a device able to be used in research to validate models describing the performance of LCDs and...

DRIVER (Spanish)

57

Liquid crystals from C3-symmetric mesogens for second-order non-linear optics

Hennrich, Gunther; Omenat, Ana; Asselberghs, Inge; Foerier, Stijn; Clays, Koen; Verbiest, Thierry; Serrano, José Luis
2006-03-24

Digital.CSIC (Spain)

58

Liquid crystalline semifluorinated ionic dendrimers

Martín-Rapún, Rafael; Marcos, Mercedes; Omenat, Ana; Serrano, José Luis; Taffin de Givenchy, Elisabeth; Guittard, Frederic
2007-03-01

Digital.CSIC (Spain)

59

Light-driven supramolecular chirality in propeller-like hydrogen-bonded complexes that show columnar

Vera, Francisco; Tejedor, Rosa M.; Romero, Pilar; Barberá, Joaquín; Ros, M. Blanca; Serrano, José Luis; Sierra, Teresa
2007-01-01

Digital.CSIC (Spain)

61

LCTF Spectral Parameters Stability

Pons, Alicia; Peralta, Celia; Campos, Joaquín; Negueruela, Angel I.; Rabal, A.; Martínez, T.
2009-01-01

Digital.CSIC (Spain)

62

LCTF Spectral Parameters Stability

Pons, Alicia; Peralta, Celia; Campos, Joaquín; Negueruela, Ángel I.; Rabal, A.; Martínez, T.
2010-01-01

Digital.CSIC (Spain)

63

Ionic Liquid Crystal Dendrimers with Mono-, Di- and Trisubstituted Benzoic Acids.

Marcos, Mercedes; Martín-Rapún, Rafael; Omenat, Ana; Barberá, Joaquín; Serrano, José Luis
2006-01-01

Digital.CSIC (Spain)

69

Highly fluorescent crystalline and liquid crystalline columnar phases of pyrene-based structures

Hayer, Anna; Halleux, Véronique de; Köhler, Anna; El-Garoughy, Abdel; Meijer, E. W.; Barberá, Joaquín; Tant, Julien; Levin, Jeremy; Lehmann, Matthias; Gierschner, Johannes; Cornil, Jérôme; Henri Geerts, Yves
2006-03-29

Digital.CSIC (Spain)

70

Formation of mesostructured silica in nonionic fluorinated surfactant systems

Esquena, Jordi; Rodríguez-Abreu, Carlos; Solans, Conxita; Kunieda, Hironobu
2006-02-23

Digital.CSIC (Spain)

71

Formation and properties of reverse micellar cubic liquid crystals and derived emulsions

Rodríguez-Abreu, Carlos; Shrestha, Lok Kumar; Varade, Dharmesh; Aramaki, Kenji; Maestro, Alicia; López Quintela, Arturo

8 pages, 11 figures.-- PMID: 17910486 [PubMed].-- Supporting information (Suppl. figures S1-S3, 3 pages) available at: http://pubs.acs.org/doi/suppl/10.1021/la701722f/suppl_file/la701722f-file001.pdf | Printed version published Oct 23, 2007 | The structure of the reverse micellar cubic (I2) liquid c...

DRIVER (Spanish)

72

Formation and properties of reverse micellar cubic liquid crystals and derived emulsions

Rodríguez-Abreu, Carlos; Shrestha, Lok Kumar; Varade, Dharmesh; Aramaki, Kenji; Maestro, Alicia; López Quintela, Arturo; Solans, Conxita
2007-10-02

Digital.CSIC (Spain)

73

Fluorene-based liquid crystalline networks with linearly polarized blue emission.

Millaruelo, Marta; Chinellato Jr., Luiz S.; Serrano, José Luis; Oriol, Luis; Piñol, Milagros
2007-09-14

Digital.CSIC (Spain)

74

Estudio del campo primario del Al2O3 en el sistema cuaternario Al2O3-CaO-MgO-SiO2

Vázquez, B.; Pena Castro, María del Pilar; Caballero Cuesta, Ángel
2004-01-01

Digital.CSIC (Spain)

75

Estudio de un cálculo intestinal en un paciente con adenocarcinoma de colón: ¿es similar a los cálculos renales?/ Study of a intestinal enteroliths in human patient with colon adenocarcinome: Is it similar to renal calculi?

Traba Villameytide, M.L.; Orts Costa, J.A.; Morell, M.
2006-02-01

Resumen en español Este trabajo muestra el estudio realizado a enterolitos intestinales procedentes de un paciente de 91 años que padecía una enterolitiasis múltiple confirmada por estudio radiológico abdominal y TAC, mostrando cálculos en el tracto intestinal, renal y biliar. Además esta enterolitiasis estaba asociada a un adenocarcinoma de colon. Los enterolitos analizados proceden de una intervención quirúrgica en la que se practicó una hemicolectomía derecha. Los enterolitos s (mas) e sometieron a un análisis por espectrometría de infrarrojos (IR) observándose un espectro de carbonato apatita no-estequiométrica, tipo whitloquita, posiblemente con materia orgánica. Con el fin de estudiar el posible contenido de diversos elementos químicos, se practicó un análisis por espectrometría de emisión atómica encontrándose, fundamentalmente, los iones Ca, Mg, K, Na y K (del orden de mg/100 mg de cálculo) y Zn, Ba, Mn, Fe, Cu, Si, Ti y Br en menor proporción (del orden de µg/100 mg de cálculo). Dada la morfología del cálculo y su espectro de IR (carbonato apatita no estequiométrica) se determinó la posible presencia de porfirinas por cromatografía líquida de alta resolución (HPLC) encontrándose, fundamentalmente, coproporfirina (µg/g de cálculo) y en menor proporción uroporfirina, protoporfirina y hepta-carboxi porfirina. El estudio se completó con el análisis de los enterolitos mediante microscopía electrónica de barrido y EDX. El análisis por difracción de rayos X detectó la presencia de CaP4O11. Los resultados obtenidos de los diferentes análisis muestran que la composición de los enterolitos es similar a la de los cálculos renales, aunque su morfología difiera de estos. Resumen en inglés This work shows the study performance to intestinal enterolithis from a 91 year old patient with multiple enterolithiasis confirmed by abdominal X-ray and TAC analyses showing the presence of intestinal, renal and bile stones. This enterolithis is associated with colon adenocarcinoma. The enteroliths were obtained by hemicolectomia and were analyzed by infrared spectroscopy (IR), giving nonstoichiometry carbonate apatite whitloquite-like with, possibly, organic material. (mas) By atomic emission spectroscopy we found Ca, Mg, K, Na y K (mg/100 mg of calculi) and Zn, Ba, Mn, Fe, Cu, Si, Ti and Br in minor proportion (µg/100 mg of calculi). Because of calculi morphology and the IR spectra (non-stoichiometry carbonate apatite) we carried out analysis by high performance liquid chromatography (HPLC) and found coproporphyrin (about µg/g of calculi) and uroporphyrin, protoporphyrin and heptacarboxy-porphyrin in minor extent. Calculi were also studied by scanning electronic microscopy and EDX and X-ray diffraction giving crystals of CaP4O11. All these results show that intestinal enteroliths composition are similar to renal calculi although its morphology differs from renal calculi.

Scientific Electronic Library Online (Spanish)

76

Electroactive C3 symmetric discotic liquid-crystalline triindoles

Gómez-Lor, Berta; Alonso, Beatriz; Omenat, Ana; Serrano, José Luis
2006-11-01

Digital.CSIC (Spain)

77

El fraccionamiento por cristalización del biodiesel de aceite de palma como alternativa para mejorar sus propiedades de flujo a baja temperatura/ Crystallization fractionation of palm oil biodiesel as an alternative for improving its cold flow properties

Benavides, Alirio Yovany; Benjumea, Pedro Ne; Agudelo, John Ramiro
2008-03-01

Resumen en español El biodiesel de aceite de palma (BAP) posee excelentes propiedades como combustible para motores. Sin embargo, asociado con su composición química altamente saturada, este biocombustible presenta un deficiente desempeño a temperaturas cercanas a la temperatura ambiente de varias ciudades colombianas. A 16 °C, el BAP empieza a formar pequeños cristales, los cuales, a medida que la temperatura sigue disminuyendo, aceleran su crecimiento y se aglomeran, de tal modo, que (mas) a una temperatura entre 12 y 9 °C pueden llegar a impedir completamente el flujo del combustible. En este trabajo se evaluó la técnica del fraccionamiento del BAP mediante cristalización inducida por enfriamiento para mejorar sus propiedades de flujo a baja temperatura (PFBT). Las variables tenidas en cuenta para dicho proceso fueron la temperatura de enfriamiento o de winterization (Tw) y el tiempo de estabilización (tp). De acuerdo con los punto de nube (PN) y fluidez (PF) del BAP, el rango de temperaturas de enfriamiento que se pudo ensayar fue muy limitado (12 °C-16 °C). El proceso permitió obtener una fracción líquida a la Tw con mejores PFBT que el BAP original. Para las condiciones extremas probadas (tp=24 horas y Tw=14 °C) se obtuvo una fracción líquida con un PN 6 °C menor que el del BAP sin fraccionar. Dicho cambio en el PN correspondió a un aumento en el contenido de metilésteres insaturados de 4,7% y una reducción en el contenido de metilésteres del ácido palmítico de 5,29%. Los cambios inducidos en la composición química de las fracciones líquidas no alcanzaron a tener efectos significativos en sus propiedades básicas como combustibles. Resumen en inglés Palm oil biodiesel (POB) has excellent properties as a fuel for engines. However, due to its highly saturated chemical composition, this biofuel presents a faulty performance at temperatures close to the environmental temperature of several Colombian cities. At 16 °C, POB begins to form small crystals which grow and form agglomerates as the temperature continues decreasing, in such a way they can completely plug the fuel flow at temperatures between 12 °C and 9 °C. In (mas) this work, the fractionation technique of POB by crystallization induced by cooling was evaluated for improving its cold flow properties. The cooling or winterization temperature (Tw) and the stabilization time (ts) were the variables taken into account in the fractionation process. According to the values of the cloud point (CP) and pour point (PP) of the POB, the range for Tw tested was very limited (12 °C-16 °C). The process allowed the production of a liquid fraction, at Tw, with better cold flow properties than those of the original POB. For the extreme tested conditions (ts=24 hours and Tw=14 °C), a liquid fraction having a CP of 6 °C lower than the original POB was obtained. Such a change in the CP corresponded to an increase in the unsaturated methyl esters content of 4,7% and a reduction of the palmitic acid methyl esters content of 5,29%. The induced changes in the chemical composition of liquid fractions did not have significant effects on their fuel basic properties.

Scientific Electronic Library Online (Spanish)

78

Effect of water on foaming properties of diglycerol fatty acid ester-oil systems

Shrestha, Lok Kumar; Shrestha, Rekha Goswami; Solans, Conxita; Aramaki, Kenji
2007-05-25

Digital.CSIC (Spain)

79

Effect of particle geometry on phase transitions in two-dimensional liquid crystals

Martínez Ratón, Yuri; Velasco, Enrique; Mederos, Luis
2005-01-26

Digital.CSIC (Spain)

80

Dobles wolframatos y dobles molibdatos tetragonales para láseres en λ = 2 μm

Serrano Hernández, M.D.; Cano Torres, José María
2010-01-01

Digital.CSIC (Spain)

81

Direct synthesis of graphitic carbon nanostructures from saccharides and their use as electrocatalytic supports

Sevilla Solís, Marta; Sanchís, C.; Valdés-Solís Iglesias, Teresa; Morallón, E.; Fuertes Arias, Antonio Benito
2008-03-04

Digital.CSIC (Spain)

82

Cyclotriphosphazene as a dendritic core for the preparation of columnar supermolecular liquid crystals

Barberá, Joaquín; Jiménez, Josefina; Laguna, Antonio; Oriol, Luis; Pérez, Sonia; Serrano, José Luis
2006-10-20

Digital.CSIC (Spain)

84

Cluster Crystals in Confinement

Van Teeffelen, Sven; Moreno Segurado, Angel J.; Likos, Christos N.

17 pages, 19 figures.-- PACS numbers: 64.70.Dv, 82.30.Nr, 61.20.Ja, 82.70.Dd. | A large class of fluids of particles interacting via ultrasoft, repulsive pair potentials crystallize into cluster crystals. Here, we employ density functional theory and computer simulations to study the behavior of a s...

DRIVER (Spanish)

85

Cluster Crystals in Confinement

Van Teeffelen, Sven; Moreno Segurado, Ángel J.; Likos, Christos N.
2008-08-09

Digital.CSIC (Spain)

86

Characterization by Fourier Transform Infrared Spectroscopy (FT-IR) and 2D IR Correlation Spectroscopy of PAMAM Dendrimer.

Popescu, Maria-Cristina; Filip, Daniela; Vasile, Cornelia; Cruz, C.; Rueff, Jean-Michel; Marcos, Mercedes; Serrano, José Luis; Singurel, Gh.
2006-06-30

Digital.CSIC (Spain)

87

Carbonate and Phosphate Precipitation by Chromohalobacter marismortui

Angustias Rivadeneyra, María; Martín-Algarra, Agustín; Sánchez-Navas, A.; Martín-Ramos, Daniel
2006-03-01

Digital.CSIC (Spain)

88

Calibrating the elements of a multispectral imaging system

López-Álvarez, Miguel A.; Hernández-Andrés, Javier; Romero, Javier; Campos, Joaquín; Pons, Alicia
2009-05-01

Digital.CSIC (Spain)

89

Calcite precipitation by high-pressure CO2 carbonation route.

Domingo, C.; Loste, Eva; Gómez-Morales, J.; García Carmona, Jesús; Fraile Sáinz, Julio
2006-01-01

Digital.CSIC (Spain)

90

Achiral bent-core liquid crystals with azo and azoxy linkages: structural and nonlinear optical properties and photoisomerization

Folcia, César L.; Alonso, I.; Ortega, Josu; Etxebarria, Jesús; Pintre, Inmaculada C.; Ros, M. Blanca
2006-08-26

Digital.CSIC (Spain)