Determination of the molar extinction coefficient for the ferric reducing/antioxidant power assay

The FRAP reagent contains 2,4,6-tris(2-pyridyl)-s-triazine, which forms a blue-violet complex ion in the presence of ferrous ions. Although the FRAP (ferric reducing/antioxidant power) assay is popular and has been in use for many years, the correct molar extinction coefficient of this complex ion under FRAP assay conditions has never been published, casting doubt on the validity of previous calibrations. A previously reported value of 19.800 is an underestimate. We determined that the molar extinction coefficient was 21,140. The value of the molar extinction coefficient was also shown to depend on the type of assay and was found to be 22,230 under iron assay conditions, in good agreement with published data. Redox titration indicated that the ferrous sulfate heptahydrate calibrator recommended by Benzie and Strain, the FRAP assay inventors, is prone to efflorescence and, therefore, is unreliable. Ferrous ammonium sulfate hexahydrate in dilute sulfuric acid was a more stable alternative. Few authors publish their calibration data, and this makes comparative analyses impossible. A critical examination of the limited number of examples of calibration data in the published literature reveals only that Benzie and Strain obtained a satisfactory calibration using their method. (C) 2011 Elsevier Inc. All rights reserved.

Signal enhancement of surface plasmon resonance immunoassay using enzyme precipitation-functionalized gold nanoparticles: A femto molar level measurement of anti-glutamic acid decarboxylase antibody

Colloidal gold nanoparticles (AuNPs) and precipitation of an insoluble product formed by HRP-biocatalyzed oxidation of 3,3'-diaminobenzidine (DAB) in the presence of H2O2 were used to enhance the signal obtained from the surface plasmon resonance (SPR) biosensor. The AuNPs were synthesized and functionalized with HS-OEG(3)-COOH by self assembling technique. Thereafter, the HS-OEG3-COOH functionalized nanoparticles were covalently conjugated with horseradish peroxidase (HRP) and anti IgG antibody to form an enzyme-immunogold complex. Characterizations were performed by several methods: UV-vis absorption, DLS, HR-TEM and Fr-IR. The Au-anti IgG-HRP complex has been applied in enhancement of SPR immunoassay using a sensor chip constructed by 1:9 molar ratio of HS-OEG(6)-COOH and HS-OEG(3)-OH for detection of anti-GAD antibody. As a result, AuNPs showed their enhancement as being consistent with other previous studies while the enzyme precipitation using DAB substrate was applied for the first time and greatly amplified the SPR detection. The limit of detection was found as low as 0.03 ng/ml of anti-GAD antibody (or 200 fM) which is much higher than that of previous reports. This study indicates another way to enhance SPR measurement, and it is generally applicable to other SPR-based immunoassays.

Double-enhancement strategy: a practical approach to a femto-molar level detection of prostate specific antigen--1-antichymotrypsin (PSA/ACT complex) for SPR immunosensing

Prostate specific antigen-a1-antichymotrypsin was detected by a double-enhancement strategy involving the exploitation of both colloidal gold nanoparticles (AuNPs) and precipitation of an insoluble product formed by HRP biocatalyzed oxidation. The AuNPs were synthesized and conjugated with horse-radish peroxidase-PSA polyclonal antibody by physisorption. Using the protein-colloid for SPR-based detection of the PSA/ACT complex showed their enhancement as being consistent with other previous studies with regard to AuNPs enhancement, while the enzyme precipitation using DAB substrate was applied for the first time and greatly amplified the signal. The limit of detection was found at as low as 0.027 ng/ml of the PSA/ACT complex (or 300 fM), which is much higher than that of previous reports. This study indicates another way to enhance SPR measurement, and it is generally applicable to other SPR-based immunoassays.

Excess molar volumes and excess molar enthalpies in binary systems N-alkyl-triethylammonium bis(trifluoromethylsulfonyl)imide plus methanol

In the present paper, a study on the influence of the alkyl chain length in N-alkyl-triethylammonium bis(trifluoromethylsulfonyl)imide ionic liquids, [N_R,222][Tf₂N] (R   = 6, 8 or 12), on the excess molar enthalpy at 303.15 K and excess molar volume within the temperature interval (283.15–338.15 K) of ionic liquid + methanol mixtures is carried out. Small excess molar volumes with highly asymmetric curves (i.e. S-shape) as a function of mole fraction composition were obtained, with negative values showing in the methanol-rich regions. The excess molar volumes increase with the increase of the alkyl-chain length of the ammonium cation of the ionic liquid and decrease with temperature. The excess enthalpies of selected binary mixtures are positive over the whole composition range and increase slightly with the length of the alkyl side-chain of the cation on the ionic liquid. Both excess properties were subsequently correlated using a Redlich–Kister-type equation, as well as by using the ERAS model. From this semipredictive model the studied excess quantities could be obtained from its chemical and physical contribution. Finally, the COSMOThermX software has been used to evaluate its prediction capability on the excess enthalpy for investigated mixtures at 303.15 K and 0.1 MPa. From this work, it appears that COSMOThermX method predicts this property with good accuracy of approx. 10%, providing at the same time the correct order of magnitude of the partial molar excess enthalpies at infinite dilution for the studied ILs,

Embarazo ectópico cervical presentación de un caso y revisión de la literatura [por] Hugo Alberto Cepeda López

Tesis (Especialidad en Ginecología y Obstetricia). U. A. N. L.

Regeneración ósea guiada en distal del segundo molar inmediata a la cirugía del tercer molar

Tesis (Maestría en Ciencias Odontológicas con especialidad en Periodoncia ) U.A.N.L.

Tratamiento ortodontico para la corrección de la clase II molar con el uso de la barra palatina T unido a un miniimplante.

Tesis (Maestría en Ciencias Odontológicas con orientación en Ortodoncia) UANL, 2014.

Factores de riesgo asociados a embarazo ectópico

Introducción: El embarazo ectópico es la primera causa de mortalidad materna durante el primer trimestre del embarazo, y la realidad sociocultural de nuestro país indica que las mujeres están exponiéndose cada vez más a factores que aumentan el riesgo para embarazo ectópico. Se pretende evaluar la asociación de los factores de riesgo en una institución de cuarto nivel. Metodología: Se realizó un estudio de casos y controles, con un caso por cada dos controles, escogidos por medio de un muestreo aleatorio simple. Resultados: Se incluyó un total de 200 pacientes. Ambas poblaciones fueron comparables. La edad promedio de casos fue 29 años y de los controles 24.6 años; la mayoría estaban casadas o en unión libre. Con respecto a los factores de riesgo con resultados estadísticamente significativos (p 0,000) se encontró que existe un mayor riesgo de embarazo ectópico con edad entre 18-35 años, estrato socioeconómico bajo, presencia de ETS, estar casada, tener periodo intergenésico prolongado, haber tenido cirugías pélvicas previas, no usar anticonceptivos, tener endometriosis y tener antecedente de embarazo ectópico (p=0,000). El factor de riesgo más alto es el antecedente de un embarazo ectópico previo OR 66.2 IC95% 60.4 – 72.0 seguido de tener endometriosis con OR 20.2 IC95% 18.6 – 21.9. (p 0,000). Discusión: Los factores de riesgo para embarazo ectópico en el presente estudio son concordantes con otros descritos en la literatura. Es importante conocer a fondo los datos presentados para mejorar los índices de esta patología a nivel nacional.

Un proyecto Grundtvig en el centro comarcal EPA El Molar.

Presenta un proyecto de innovación desarrollado por el Centro Comarcal de EPA 'El Mola' dentro de los programas de acción Grundtvig. A este programa están adscritos Bélgica, Reino Unido, Lituania, Hungría, Suiza y España y la finalidad es estudiar líneas de actuación para progresar en la promoción de la participación de las comunidades educativas en sus centros respectivos. Se centra en el proceso seguido en el CEPA del El Molar en la coordinación, el desarrollo de las actividades y el producto final de la experiencia.

Shear controlled crystal size definition in a low molar mass compound using a polymeric solvent

We show that close to monodisperse crystalline fibrils of dibenzylidene sorbitol can be obtained by preparation in a polymeric solvent subjected to extended shear flow.