Investigations in flow injection analysis (FIA): conventional FIA determination of chloride in water; sequential injection (SI)-FIA determination of mercury in water

Flow injection analysis (FIA) was applied to the determination of both chloride ion and mercury in water. Conventional FIA was employed for the chloride study. Investigations of the Fe3 +/Hg(SCN)2/CI-,450 nm spectrophotometric system for chloride determination led to the discovery of an absorbance in the 250-260 nm region when Hg(SCN)2 and CI- are combined in solution, in the absence of iron(III). Employing an in-house FIA system, absorbance observed at 254 nm exhibited a linear relation from essentially 0 - 2000 Jlg ml- 1 injected chloride. This linear range spanning three orders of magnitude is superior to the Fe3+/Hg(SCN)2/CI- system currently employed by laboratories worldwide. The detection limit obtainable with the proposed method was determin~d to be 0.16 Jlg ml- 1 and the relative standard deviation was determined to be 3.5 % over the concentration range of 0-200 Jig ml- 1. Other halogen ions were found to interfere with chloride determination at 254 nm whereas cations did not interfere. This system was successfully applied to the determination of chloride ion in laboratory water. Sequential injection (SI)-FIA was employed for mercury determination in water with the PSA Galahad mercury amalgamation, and Merlin mercury fluorescence detection systems. Initial mercury in air determinations involved injections of mercury saturated air directly into the Galahad whereas mercury in water determinations involved solution delivery via peristaltic pump to a gas/liquid separator, after reduction by stannous chloride. A series of changes were made to the internal hardware and valving systems of the Galahad mercury preconcentrator. Sequential injection solution delivery replaced the continuous peristaltic pump system and computer control was implemented to control and integrate all aspects of solution delivery, sample preconcentration and signal processing. Detection limits currently obtainable with this system are 0.1 ng ml-1 HgO.

Crystallinity, Magnetic and Electrical Properties of Bi doped LaVO3

We report the results of crystal structure, magnetization and resistivity measurements of Bi doped LaVO3. X-ray diffraction (XRD) shows that if doping Bi in the La site is less than ten percent, the crystal structure of La1-xBixVO3 remains unchanged and its symmetry is orthorhombic. However, for higher Bi doping (>10%) composite compounds are found where the XRD patterns are characterized by two phases: LaVO3+V2O3. Energy-dispersive analysis of the x-ray spectroscopy (EDAX) results are used to find a proper atomic percentage of all samples. The temperature dependence of the mass magnetization of pure and single phase doped samples have transition temperatures from paramagnetic to antiferromagnetic region at TN=140 K. This measurement for bi-phasic samples indicates two transition temperatures, at TN=140 K (LaVO3) and TN=170 K (V2O3). The temperature dependence of resistivity reveals semiconducting behavior for all samples. Activation energy values for pure and doped samples are extracted by fitting resistivity versus temperature data in the framework of thermal activation process.

SI

Dark brown sediment with clasts ranging from small to large. Clasts range from angular to sub-rounded. Lineations are abundant in this sample, along with comet structures. Grain stacks and rotation structures can also be seen in minor amounts.

Micronúcleos (MN) e intercambio de cromátides hermanas (ICH) como pruebas indicadoras de la acción mutagénica de diazepam y del difenilhidantoinato de sodio.

Tesis (Maestría en Ciencias con Especialidad en Genética) UANL

Nuevos conductores de ion litio en los sistemas Li2O-AlO3-MO2, M=Si,Ge

Tesis (Maestría en Ciencias con Especialidad en Físicoquímica) UANL

Caracterización electroquímica de la inserción de litio en MnNb2O6 (M= Mn, Co, Ni, Cu, Zn, Cd) y en Li3X2NbO6 (X= Mn, Co, Ni)

Tesis (Maestría en Ciencias con Especialidad en Ingeniería Cerámica) UANL

Frecuencias de grupos sanguíneos ABO, Rho (D) Mn. e isominia en personas con apellidos mono y polifiléticos del área metropolitana de Monterrey, Nuevo León [por] Ma. de los Angeles Rojas Alvarado

Tesis (Maestro en Ciencias con especialidad en Genética)

Modelación de la transferencia de calor en una aleación Al-Si tipo 319 [por] Jesús Talamantes Silva

Tesis (Maestría en Ciencias de la Ingeniería Mecánica con Especialidad en Materiales) U.A.N.L.

Efecto de la temperatura de solubilización sobre las propiedades mecánicas en una aleación AL-SI tipo A319 [por] César Gerardo Dimas Acevedo

Tesis (Maestría en Ciencias de la Ingeniería Mecánica con Especialidad en Materiales) U.A.N.L.

Inserción electroquímica de litio en compuestos de fórmula general MWO4 (M= Co, Cu, Mn, Ni, Zn, y Zn) preparados por dos rutas de síntesis [por] Sagrario Martínez Montemayor

Tesis (Maestría en Ciencias con Especialidad en Ingeniería Cerámica) U.A.N.L.

Estudios de deformación cíclica en una aleación Al-Si tipo A319 por José Iván Suárez Gutiérrez

Tesis (Maestría en Ciencias de la Ingeniería Mecánica con Especialidad en Materiales) U.A.N.L.

Análisis microestructural de una aleación A1-Si del tipo A319

Tesis (Maestría en Ciencias de la Ingeniería Mecánica con Especialidad en Materiales) - U.A.N.L, 2001

Fractografía autoafín 3 D en una aleación Al-Si

Tesis ( Maestro en Ciencias de la Ingeniería Mecánica con Especialidad en Materiales) U.A.N.L.

Disolución de la fase teta en una aleación AL-SI con tres diferentes contenidos de cobre

Tesis ( Maestro en Ciencias de la Ingeniería Mecánica con Especialidad en Materiales) U.A.N.L.

Contenido de Fe, Mn, y Zn en nogal (Carya illinoensis, L. Koch) en huertas comerciales de Bustamante, Nuevo León

Tesis ( Maestro en Ciencias en Producción Agrícola) U.A.N.L.