Remarks on the representation theory of the Moyal plane

We present an explicit construction of a unitary representation of the commutator algebra satisfied by position and momentum operators on the Moyal plane.Comment: 10 pages, minor changes, refs. adde

Neutrino mixing and masses in a left-right model with mirror fermions

In the framework of a left-right model containing mirror fermions with gauge group SU(3)$_{C} \otimes SU(2)_{L} \otimes SU(2)_{R} \otimes U(1)_{Y^\prime}$, we estimate the neutrino masses, which are found to be consistent with their experimental bounds and hierarchy. We evaluate the decay rates of the Lepton Flavor Violation (LFV) processes $\mu \rightarrow e \gamma$, $\tau \rightarrow \mu \gamma$ and $\tau \rightarrow e\gamma$. We obtain upper limits for the flavor-changing branching ratios in agreement with their present experimental bounds. We also estimate the decay rates of heavy Majorana neutrinos in the channels $N \rightarrow W^{\pm} l^{\mp}$, $N \rightarrow Z \nu_{l}$ and $N \rightarrow H \nu_{l}$, which are roughly equal for large values of the heavy neutrino mass. Starting from the most general Majorana neutrino mass matrix, the smallness of active neutrino masses turns out from the interplay of the hierarchy of the involved scales and the double application of seesaw mechanism. An appropriate parameterization on the structure of the neutrino mass matrix imposing a symmetric mixing of electron neutrino with muon and tau neutrinos leads to Tri-bimaximal mixing matrix for light neutrinos.Comment: Accepted by European Physical Journal

On the noncommutative eikonal

We study the eikonal approximation to quantum mechanics on the Moyal plane. Instead of using a star product, the analysis is carried out in terms of operator-valued wavefunctions depending on noncommuting, operator-valued coordinates.Comment: 18 page

On the noncommutative eikonal

We study the eikonal approximation to quantum mechanics on the Moyal plane. Instead of using a star product, the analysis is carried out in terms of operator-valued wavefunctions depending on noncommuting, operator-valued coordinates

Synthesis of geopolymer from spent FCC: Effect of SiO2/Al2O3 and Na2O/SiO2 molar ratios

This paper assesses the feasibility of using a spent fluid catalytic cracking catalyst (SFCC) as precursor for the production of geopolymers. The mechanical and structural characterization of alkali-activated SFCC binders formulated with different overall (activator + solid precursor) SiO2/Al2O3 and Na2O/SiO2 molar ratios are reported. Formation of an aluminosilicate ‘geopolymer’ gel is observed under all conditions of activation used, along with formation of zeolites. Increased SiO2/Al2O3 induces the formation of geopolymers with reduced mechanical strength, for all the Na2O/SiO2 ratios assessed, which is associated with excess silicate species supplied by the activator. This is least significant at increased alkalinity conditions (higher Na2O/SiO2 ratios), as larger extents of reaction of the spent catalyst are achieved. SiO2/Al2O3 and Na2O/SiO2 ratios of 2.4 and 0.25, respectively, promote the highest compressive strength (67 MPa). This study elucidates the great potential of using SFCC as precursor to produce sustainable ceramic-like materials via alkali-activation

Caracterización química y cuantificación del rendimiento de extracción de pigmento en siete accesiones mexicanas de Bixa orellana

Achiote (Bixa orellana) is a plant used for obtaining a natural dye rich on carotenoids (mainly bixin and norbixin); it is also the plant species with the highest content of tocotrienols in nature. In the present work, the pigment extraction yield of seven Mexican accessions of Bixa orellana was quantified. Also color parameters and content of tocotrienols, tocopherols, norbixin, bixin, total phenolic compounds and antioxidant capacity were evaluated in the corresponding annatto extracts. The highest percentage of pigment extraction yield was obtained with KOH (4.84%). Accessions 43 (L*= 4.01 ± 0.79, C*= 7.33 ± 1.07, h= 25.76 ± 6.35) and 50 (L*= 3.17 ± 0.64, C*= 6.81 ± 0.53, h= 26.41 ± 4.41) had the lowest color values, meaning these accessions had a darker and redder color. Four accessions showed the highest content of bixin: accession 48 (3.1%), 45 (2.6%) 43 (2.4%) and 47 (2.2%). Accession 50 had showed the highest content of total phenolic compounds and of tocotrienols (T3), mainly the isoform δ-T3 (5.03 ± 0.64 mg g−1 Seed Dry Weight), as well as the highest antioxidant capacity.El achiote (Bixa orellana) es una planta utilizada para obtener un colorante natural rico en carotenoides (principalmente bixina y norbixina); además, es la especie vegetal con el mayor contenido de tocotrienoles. En este trabajo, se determinó el rendimiento de extracción de pigmento de siete accesiones mexicanas de Bixa orellana. También se evaluaron los parámetros de color y el contenido de tocotrienoles, tocoferoles, norbixina, bixina, compuestos fenólicos totales y la capacidad antioxidante en extractos de annato. El mayor porcentaje de rendimiento de extracción de pigmento fue obtenido con KOH (4.847905%). Las accesiones 43 (L*= 4.01 ± 0.79, C*= 7.33 ± 1.07, h= 25.76 ± 6.35) y 50 (L*= 3.17 ± 0.64, C*= 6.81 ± 0.53, h= 26.41 ± 4.41) presentaron los valores más bajos de los párametros de color, lo que significa que estas accesiones tuvieron un color más oscuro y más rojo. Cuatro accesiones mostraron el mayor contenido de bixina: accesión 48 (3.1%), 45 (2.6%) 43 (2.4%) and 47 (2.2%). La accession 50 mostró el mayor contenido de compuestos fenólicos totales y de tocotrienoles (T3), principalmente la isoforma δ-T3 (5.03 ± 0.64 mg g-1 Peso Seco), así como también la mayor capacidad antioxidante.Fil: Raddatz Mota, D.. Universidad Autónoma Metropolitana; MéxicoFil: Pérez Flores, L. J.. Universidad Autónoma Metropolitana; MéxicoFil: Carrari, Fernando Oscar. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; ArgentinaFil: Insani, Ester Marina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Biotecnología; ArgentinaFil: Asis, Ramón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; ArgentinaFil: Mendoza Espinoza, J. A.. Universidad Nacional Autónoma de México; MéxicoFil: Díaz de León Sánchez, F.. Universidad Autónoma Metropolitana; MéxicoFil: Rivera Cabrera, F.. Universidad Autónoma Metropolitana; Méxic

A MECHANICAL METHOD FOB EXTRACTING TAMARIND PULP

A MECHANICAL METHOD FOB EXTRACTING TAMARIND PUL

Neutrino masses and mixing parameters in a left-right model with mirror fermions

In this work we consider a left-right model containing mirror fermions with gauge group SU(3)$_{C} \otimes SU(2)_{L} \otimes SU(2)_{R} \otimes U(1)_{Y^\prime}$. The model has several free parameters which here we have calculated by using the recent values for the squared-neutrino mass differences. Lower bound for the mirror vacuum expectation value helped us to obtain crude estimations for some of these parameters. Also we estimate the order of magnitude of the masses of the standard and mirror neutrinos.Comment: 13 pages, version submitted to European Physical Journal

Magnetoelectric coupling in polycrystalline FeVO4

We report coupling between magnetic and electric orders for antiferromagnetic polycrystalline FeVO4 in which magnetism-induced polarization has been recently found in noncollinear antiferromagnetic state below the second antiferromagnetic phase transition at TN2=15.7K. In this low symmetry phase space group P-1, the magnetic field dependence of electric polarization evidences a clear magnetoelectric coupling in the noncollinear spin-configured antiferromagnetic phase. The discontinuity of magnetodielectric effect observed at the vicinity of the polar to nonpolar transition evidences competition between different magnetodielectric couplings in the two different antiferromagnetic states. The existence of thermal expansion anomaly near TN2 and magnetostriction effect support magnetoelastically mediated scenario of the observed magnetoelectric effect.Comment: 4 pages, 6 figures, Phys. Rev. B 80, 172103 (2009

Estabilización de suelo arcilloso utilizando materiales cementicios activados alcalinamente

In this study, a clayey soil classified as A-7-5 according ASTM D3282, was stabilized using alkali-activated cementitious materials (AAC) added to the soil dry in percentages of 20 and 30%. Fly ash (F1, F2) with high unburned carbon content (up to 38.76%), hydrated lime (L) and granulated blast furnace slag were used. Unconfined compressive strength and flexural strength at 28 days of curing and the durability after 12 wetting-drying cycles were evaluated. The results were compared with a soil-cement reference mixture. The soil treated with AAC-F1L showed a volume expansion of 0.51% and volume contraction of -0.57% compared with the 0.59% expansion and -0.68% contraction of the soil-cement reference mixture. Additionally, the mass loss after the wetting and drying cycles is only 3.74% which is slightly lower than the mass loss of the soil stabilized with ordinary Portland cement (OPC) (3.86%) and well below the value specified in Colombian regulations (7%).En este estudio, un suelo arcilloso clasificado como A-7-5 según ASTM D3282, se estabilizó utilizando materiales activados alcalinamente (AAC) en porcentajes de 20 y 30%. Se utilizaron cenizas volantes (F1, F2) con alto contenido de inquemados (hasta 38,76%), cal hidratada (L) y escoria granulada de alto horno. Se evaluó la resistencia a la compresión confinada y la resistencia a la flexión a 28 días de curado y la durabilidad después de 12 ciclos de humectación-secado. Los resultados se compararon con una mezcla de referencia suelo-cemento. El suelo tratado con AAC-F1L mostró una expansión y contracción volumétrica del 0,51% y -0,57% respectivamente, en comparación con el 0,59% y -0,68% de la mezcla de referencia suelo-cemento. Además, la pérdida de masa después de los ciclos de humectación y secado es sólo 3.74%, valor ligeramente inferior a la del suelo estabilizado con cemento Portland (3.86%) y muy inferior al valor especificado en la normativa colombiana (7%)