Cellulosic materials as natural fillers in starch-containing matrix-based films: a review

In this work, the different cellulosic materials, namely cellulose and lignin are analyzed. In addition, the starch-containing matrices (isolated starch and flour) reinforced with cellulosic materials to be used in packaging applications are described. Many efforts have been exerted to develop biopackaging based on renewable polymers, since these could reduce the environmental impact caused by petrochemical resources. Special attention has had the starch as macromolecule for forming biodegradable packaging. For these reasons, shall also be subject of this review the effect of each type of cellulosic material on the starch-containing matrix-based thermoplastic materials. In this manner, this review contains a description of films based on starch-containing matrices and biocomposites, and then has a review of cellulosic material-based fillers. In the same way, this review contains an analysis of the works carried out on starch-containing matrices reinforced with cellulose and lignin. Finally, the manufacturing processes of starch/cellulose composites are provided as well as the conclusions and the outlook for future works.Fil: Gutiérrez Carmona, Tomy José. Universidad Central de Venezuela; Venezuela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Variational approach to the Hubbard model in a C60 cluster

5 págs.; 4 figs.; 3 tabs.We propose a computational scheme for the Hubbard model in the C60 cluster in which the interaction with the Fermi sea of charges added to the neutral molecule is switched on sequentially. This is applied to the calculation of the balance of charging energies, within a low-energy truncation of the space of states which produces moderate errors for an intermediate range of the interaction strength. ©1996 American Physical SocietyPeer Reviewe

Phase diagram of carbon nanotube ropes

14 págs.; 9 figs.; 1 tab. ; PACS number(s): 71.20.Tx, 71.10.Pm, 74.50.1rThe zero-temperature phase diagram of carbon nanotube ropes is studied using a computational framework that incorporates the renormalization of intratube interactions and the effect of intertube Coulomb screening. This allows us to undertake a systematic analysis as a function of the number of metallic nanotubes in the rope and the effective strength of the phonon-mediated interaction. We find that there is in general a weak-coupling regime of the interactions, corresponding to Luttinger-liquid behavior in thin ropes and to superconducting behavior in sufficiently thick ropes. Furthermore, we show the existence of exotic phases in the strong-coupling regime, characterized by the appearance of charge instabilities that depend on the helicity and the doping level of the nanotubes in the rope. Our approach allows for the simultaneous analysis of the scaling of the Cooper-pair tunneling amplitude between metallic nanotubes, making it possible to discern the crossover from purely one-dimensional physics to the setting of three-dimensional Cooper-pair coherence. We provide then good estimates of the superconducting transition temperature and discuss the connection of our results with recent experiments. ©2004 American Physical SocietyJ. V. A. acknowledges support from S. Moukouri and stimulating discussions with J. Allen. J. G. acknowledges financial support from the Ministerio de Ciencia y Tecnología Grant No. BFM2003-05317.Peer Reviewe

Bionanocomposite films developed from corn starch and natural and modified nano-clays with or without added blueberry extract

Edible and bionanocomposite films were developed by extrusion followed by thermo molding. Corn starch (Zea mays), glycerol, and several nano-clays were used as the carbohydrate polymer, plasticizer and nano-fillers, respectively. Pure blueberry (Vaccinium corymbosum) extract (BE, 100% anthocyanin), as well as natural and modified montmorillonites (Mnt) with or without BE nano-packaged within their layers were incorporated into the thermoplastic starch (TPS) matrix. Previous studies by our research group have shown that BE, and BE nano-packaged within natural and modified Mnt, are pH-sensitive. With this in mind, we set out to develop edible and intelligent (pH-sensitive) bionanocomposite films with improved properties. Unfortunately however, none of the films formulated were pH-sensitive. All the films showed X-ray diffractograms typical of semicrystalline, albeit largely amorphous, materials coinciding with the morphological observations made under scanning electron microscopy. The results confirmed that total starch gelatinization occurred under the selected extrusion conditions. Films prepared from corn starch containing BE showed a plasticizing effect, giving materials with lower thermal resistance and surface moisture values, which were also more opaque, denser, and rougher. All the nano-fillers tested were completely exfoliated within the TPS matrix, except for the natural Mnt that was partly exfoliated and partly intercalated in the matrix. In general, materials containing nano-fillers with a greater degree of interlayer spacing (more exfoliated) showed higher thermal resistance and Young's modulus, but lower strain at break values.Fil: Gutiérrez Carmona, Tomy José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Alvarez, Vera Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Operaciones Bancarias : Análisis de parámetros crediticios utilizados por el banco de la producción para el otrogamiento y emisión de tarjetas de crédito visa clásica a los tarjetahabiente en el periodo enero-diciembre 2013.

El presente documento seminario de graduación aborda el impacto que hoy en día representa la falta de información y como consecuencia el uso inadecuado que se realiza a la tarjeta de crédito visa clásica emitida por el Banco de la Producción en el período EneroDiciembre 2013 . Contiene un análisis realizado a los parámetros que utilizo el Banco para el correcto otorgamiento y emisión de tarjetas de crédito. También se hace referencia a los aspectos tales como el endeudamiento, el cual ha disminuido luego de la aprobación de la reforma que se aplicó a la Ley 515 de Promoción y Ordenamiento del Uso de la Tarjeta de Crédito. Determinando que las tarjetas de crédito se han convertido en una herramienta de pago habitual conllevando, que tanta responsabilidad tiene el banco por emitir una tarjeta de crédito, como el uso que el propietario le de a ésta. Este resultado es logrado gracias al análisis documental obtenido de la información financiera y de los resultados del caso práctico, el cual demostró exactamente esa responsabilidad que debe tener el cliente en su uso adecuado de la tarjeta de crédito, que se convierte a su vez en dinero en sus manos

Contraste del análisis fundamental y el análisis técnico para el pronóstico de la tendencia del valor de una acción en el periodo 2009-2013

En el mercado accionario pronosticar el valor de una acción es una prioridad ya que permite al inversionista generar rentabilidad en el capital; la tendencia de una acción puede ser estudiada mediante dos técnicas: el análisis técnico y el análisis fundamental. Ahora bien, si alguien que ha contrastado ambas técnicas encuentra intrincado pronosticar el valor de una acción una persona limitada a sólo una de las dos técnicas podría encontrar aún más complejo predecir la tendencia de la acción de forma certera, sobre todo si se tiene en consideración que existen factores externos que generan inconsistencias en los análisis; estos factores pueden ser políticos-económicos de la misma empresa y engloban desde cambios en la estructura accionaria hasta noticias sobre los controladores principales por mencionar algunos. Los acontecimientos anteriormente mencionados afectan de manera directa a la tendencia prevista del valor de la acción establecido por los análisis bursátiles, situación que complica los pronósticos calculados por lo que se plantea como objetivo analizar los aspectos generales de ambas técnicas que permitan predecir cuándo un mercado está en tendencia, su volatilidad, la fuerza de la misma y poner en evidencia sus fortalezas o debilidades, mostrando así el efecto que tiene cada una de ellas sobre el precio de la acción y la manera en que afectan las tendencias dentro del mercado accionario al momento de contrastar el análisis fundamental con el técnico. El contraste, mediante la formulación matemática, económica e interpretación ayudará al inversionista a la hora de tomar decisiones y se buscará responder la siguiente pregunta: ¿Qué nivel de confianza presenta cada una de las técnicas, que permita pronosticar de manera certera la tendencia del valor de una acción

Radiative processes as a condensation phenomenon and the physical meaning of deformed canonical structures

Working with well known models in $(2+1)D$ we discuss the physics behind the deformation of the canonical structure of these theories. A new deformation is constructed linking the massless scalar field theory with the self-dual theory. This is the exact dual of the known deformation connecting the Maxwell theory with the Maxwell-Chern-Simons theory. Duality is used to establish a web of relations between the mentioned theories and a physical picture of the deformation procedure is suggested.Comment: revtex4 file, 16 page

Individual differences in working memory capacity modulate semantic negative priming from single prime words

The present study investigated whether semantic negative priming from single prime words depends on the availability of cognitive control resources. Participants with high vs. low working memory capacity (as assessed by their performance in complex span and attentional control tasks) were instructed to either attend to or ignore a briefly presented single prime word that was followed by either a semantically related or unrelated target word on which participants made a lexical decision. Individual differences in working memory capacity (WMC) mainly affected the processing of the ignored primes, but not the processing of the attended primes: While the latter produced reliable positive semantic priming for both high- and low-WMC participants, the former gave rise to reliable semantic negative priming only for high WMC participants, with low WMC participants showing the opposite positive priming effect. The present results extend previous findings in demonstrating that (a) single negative priming can reliably generalize to semantic associates of the prime words, and (b) a differential availability of cognitive control resources can reliably modulate the negative priming effect at a semantic level of representation

What is the status of immunotherapy in thyroid neoplasms?

Immunotherapy; Thyroid neoplasms; Tumor mutational burdenInmunoterapia; Neoplasias de la tiroides; Carga mutacional tumoralImmunoteràpia; Neoplàsies de les tiroides; Càrrega mutacional tumoralImmunotherapy has changed the treatment of patients with advanced cancer, with different phase III trials showing durable responses across different histologies. This review focuses on the preclinical and clinical evidence of potential predictive biomarkers of response and efficacy of immunotherapy in thyroid neoplasms. Programmed death-ligand 1 (PD-L1) staining by immunohistochemistry has shown higher expression in anaplastic thyroid cancer (ATC) compared to other subtypes. The tumor mutational burden in thyroid neoplasms is low but seems to be higher in ATC. Immune infiltrates in the tumor microenvironment (TME) differ between the different thyroid neoplasm subtypes. In general, differentiated thyroid cancer (DTC) has a higher number of tumor-associated lymphocytes and regulatory T cells (Tregs), while ATC and medullary thyroid cancer (MTC) display a high density of tumor-associated macrophages (TAMs). Nevertheless, results from clinical trials with immunotherapy as monotherapy or combinations have shown limited efficacy. Further investigation into new strategies aside from anti-cytotoxic T-lymphocyte antigen 4 (CTLA-4)/programmed death 1 (PD-1)/PD-L1 antibodies, validation of predictive biomarkers, and better population selection for clinical trials in thyroid neoplasms is more than needed in the near future