J2 effect and elliptic inclined periodic orbits in the collision three-body problem

The existence of a new class of inclined periodic orbits of the collision restricted three-body problem is shown. The symmetric periodic solutions found are perturbations of elliptic kepler orbits and they exist only for special values of the inclination and are related to the motion of a satellite around an oblate planet

Movimientos juveniles y estudiantiles contemporáneos: la toma de la Universidad Nacional de Tucumán, Argentina (2013)

El siguiente trabajo hace un recorrido histórico por los movimientos sociales, juveniles y estudiantiles contemporáneos europeos y latinoamericanos. Dicha revisión busca comprender la naturaleza de los movimientos, los contextos en los que emergen y las características de los mismos intentando, a su vez, rastrear los antecedentes de la toma de la Universidad Nacional de Tucumán Argentina en 2013

Models for the estimation of thermodynamic properties of layered double hydroxides: application to the study of their anion exchange characteristics

Several models for the estimation of thermodynamic properties of layered double hydroxides (LDHs) are presented. The predicted thermodynamic quantities calculated by the proposed models agree with experimental thermodynamic data. A thermodynamic study of the anion exchange process on LDHs is also made using the described models. Tables for the prediction of monovalent anion exchange selectivities on LDHs are provided. Reasonable agreement is found between the predicted and the experimental monovalent anion exchange selectivities.

Review of the synthesis of layered double hydroxides: a thermodynamic approach

The synthesis of layered double hydroxides (LDHs) by hydrothermal-LDH reconstruction and coprecipitation methods is reviewed using a thermodynamic approach. A mixture model was used for the estimation of the thermodynamics of formation of LDHs. The synthesis and solubility of LDHs are discussed in terms of standard molar Gibbs free energy change of reaction. Data for numerous divalent and trivalent metals as well as for some monovalent and tetravalent metals that may be part of the LDH structure have been compiled. Good agreement is found between theoretical and experimental data. Diagrams and tables for the prediction of possible new LDH materials are provided.

Efecto de la naturaleza del precursor sobre las caracteristicas de las nanoparticulas de SnO2 sintetizadas

Tin oxide (SnO2) is widely used in industry as raw material for electronic devices, plating of different types of materials, for dyes and pigments, for electroplating, heterogeneous catalysis, etc. In this work SnO2 was obtained by a controlled precipitation method with special attention to the effects the tin precursor has on the microstructure of the final product. The most appropriate pH for obtaining SnO2 with the rutile structure as the main phase is 6.25 for SnCl2 and 6.40 for SnSO4. After heat treatment at 600 °C, particles of nanometric order (~10 - 30 nm approx) were obtained. The characterization of the solid phase was made by X-ray diffraction (XRD), thermal analysis (DTA/TG), transmission electron microscopy (TEM) and Fourier transformed infrared spectroscopy (FTIR).

Un método reproducible para obtener peg biramificado monofuncional de alta pureza

PEGylation has become a widely applied technique to enhancing in vitro and in vivo stability of therapeutic proteins and to increasing materials biocompatibility. PEG branched structures have proven useful for protein and peptide modification. Furthermore, they may be better than linear structures for many purposes. This paper describes an improved procedure for obtaining 2-arms PEG based on L-lysine. The efficiency of the synthesis was not related to moisture of the raw materials. This procedure does not use hazardous reagents as previous protocols do. It implemented a purification process for obtaining the desired structure with high purity ( > 99%). Finally, the procedure described here allows the obtaining of others PEGylation reagents.

Estudio hidrofóbico de soluciones acuosas diluidas de isómeros de pentanodiol a varias temperaturas a partir de datos volumétricos

Density of dilute aqueous solutions of 1,2 pentanediol, 2,4 pentanediol, 1,4 pentanediol and 1,5 pentanediol at 283.15, 288.15, 293.15, 298.15, 303.15 and 308.15 K in the concentration range 0.0000 to 0.0060 in mole fraction were determined by using Wood-Brusie type capillary neck pycnometers. The solute partial molar volume as a function of solute concentration for each system was correlated with a linear equation for each temperature to estimate the slope limit and the partial molar volume at infinite dilution, and the predominant hydrophilic-hydrophobic effect was found in this region.

Interacciones de la glicina en soluciones acuosas de tetrafluoroborato de 1-butil, 3-metilimidazolio a diferentes temperaturas

Densities of glycine in aqueous solutions of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate were determined at temperatures ranging from 283.15 to 313.15 K. The apparent molar volume, infinite dilution apparent molar volume, second derivative of the infinite dilution partial molar volume with respect to temperature, partial molar volume of transfer at infinite dilution, and the number of hydration were determined. It was found that the apparent molar volume at infinite dilution was positive, but decreased with increasing ionic liquid concentration and increased with increasing temperature. On the other hand, the partial molar volume of transfer at infinite dilution behaved in a similar manner, but was negative.

Synthesis of 1H-benzoxazine-2,4-diones from heterocyclic anhydrides: evaluation of antioxidant and antimicrobial activities

A facile one-step synthesis of 1H-benzoxazine-2,4-diones from heterocyclic anhydrides and TMSA was described. This paper determines their antimicrobial activity against nine human bacterial pathogens by the broth microdilution method; antioxidant activity by DPPH• inactivation and a ferric-reducing power assay; and toxicity by a brine shrimp, Artemia salina, assay. The 1H-benzoxazine-2,4-dione yields were in the range of 57 to 98%. The novel compound 1H-pyrazino[2,3-][1,3]oxazine-2,4-dione 4c showed the highest antioxidant capacity (DPPH 35.4% and FRAP 0.063 µmol TEs/µmol).

Figuras de la antipolítica en Carl Schmitt

El presente trabajo desarrolla distintas figuras que Carl Schmitt señala como formas de subjetividad antipolítica. Si desde la perspectiva del jurista alemán las operaciones que constituyen un modo de ser político son aquellas que producen o sostienen una forma representativa, lo propio de una subjetividad antipolítica son aquellas operaciones que erosionan o conducen a la destrucción de dicha forma política. El trabajo intenta mostrar que la operación fundamental en este sentido es la dilación, entendida como la postergación indefinida de la decisión. Así, bajo las diversas figuras de la antipolítica que Schmitt aborda, esta operación también adquiere diversas formas de aparición: en el caso de la subjetividad liberal se da bajo la forma de la discusión y el compromiso, en el caso del romántico político bajo la forma de la poetización.

America

Julkaisussa: Historia delle nuove Indie occidentali, con tutti i discoprimenti & cose notabili

Insulin receptor has tyrosine kinase activity toward Shc in rat liver

Insulin induces tyrosine phosphorylation of Shc in cell cultures and in insulin-sensitive tissues of the intact rat. However, the ability of insulin receptor (IR) tyrosine kinase to phosphorylate Shc has not been previously demonstrated. In the present study, we investigated insulin-induced IR tyrosine kinase activity towards Shc. Insulin receptor was immunoprecipitated from liver extracts, before and after a very low dose of insulin into the portal vein, and incubated with immunopurified Shc from liver of untreated rats. The kinase assay was performed in vitro in the presence of exogenous ATP and the phosphorylation level was quantified by immunoblotting with antiphosphotyrosine antibody. The results demonstrate that Shc interacted with insulin receptor after infusion of insulin, and, more important, there was insulin receptor kinase activity towards immunopurified Shc. The description of this pathway in animal tissue may have an important role in insulin receptor tyrosine kinase activity toward mitogenic transduction pathways.

Evaluation of total carotenoids, alpha- and beta-carotene in carrots (Daucus carota L.) during home processing

This study aims to analyze the influence of dehydration and different preparation methods during home processing related toalpha-carotene, beta-carotene and total carotenoids stability in carrots. Vitamin A values were evaluated after different treatments. Thus, carrots were submitted to steam cooking, water cooking with and without pressure, moist/dry cooking and conventional dehydration. Determination of alpha- and beta-carotenes was made by High-Performance Liquid Chromatography (HPLC) (conditions were developed by us) using spectrophotometric detection visible-UV at 470 nm; a RP-18 column and methanol: acetonitrile: ethyl acetate (80: 10: 10) as mobile phase. Total carotenoids quantification was made by 449 nm spectrophotometer. The retention of the analyzed carotenoids ranged from 60.13 to 85.64%. Water cooking without pressure promoted higher retention levels of alpha- and beta-carotene and vitamin A values, while water cooking with pressure promoted higher retention levels of total carotenoids. Dehydration promoted the highest carotenoid losses. The results showed that, among the routinely utilized methods under domestic condition, cooking without pressure, if performed under controlled time and temperature, is the best method as it reduces losses in the amount of alpha- and beta-carotene, the main carotenoids present in the carrots. Despite the significant carotenoid losses, carrots prepared through domestic methods, remain a rich source of provitamin A.