Authors:G. Ferro-Flores, L. Ramirez-Garcia, J. Lezama, P. Garcia-Garcia, and J. Tendilla
99mTc hexakis (2-methoxyisobutylisonitrile) is a cationic complex useful as a myocardial perfusion agent. The synthesis of 2-methoxyisobutylisonitrile (MIBI) by a modified and improved procedure in a two-step process with an overall yield of 53% is described. The preparation of its copper and technetium-99m complexes is also presented.
Authors:J. Ramírez-García, M. Jiménez-Reyes, M. Solache-Ríos, E. Fernández-Ramírez, H. López-González, and A. Rojas-Hernández
The solubility of europium at 0.02M, 0.1M and 0.7M NaClO4 ionic strength solutions was determined by a radiometric method and pEus-pCH diagrams were obtained. Hydrolysis constants were also determined at the same ionic strengths by pH titration and the values found were log *
1 = -7.68±0.11, -8.07±0.10 and -8.20±0.11. The log Ksp values were -23.5±0.2, -22.7±0.2 and -21.9±0.2 for 0.02M, 0.1M and 0.7M NaClO4 ionic strengths, respectively, at 303 K under CO2-free conditions and the extrapolated value at zero ionic strength was log Ksp0 = -24.15. The working pCH ranges for the calculation of the hydrolysis constants were selected from the pEus-pCH diagrams in the region where precipitation of europium oxide or hydroxide was less than 20%. Europium removal from aqueous solutions with zeolites was explored.
Authors:T. Martinez, L. Cabrera, M. Navarrete, J. Garcia, P. Gonzalez, A. Ramirez, and U. Martinez
Gamma exposure rate and radon levels were measured in 75 single-family dwellings in Mexico City in order to correlate them with local environment. Radon monitoring was performed both indoors and outdoors using a continuous working level monitor for short-lived radon decay products; the gamma exposure rate was measured using CaSO4: Dy+PTFE. The results obtained show a log-normal distribution. The mean indoor radon concentration is lower than 45 Bq/m3 and the mean indoor gamma exposure rate was 11.29 R/h.
Authors:Carmen Ramírez, M. Rico, L. Barral, J. Díez, S. García-Garabal, and B. Montero
behaviour of an epoxy resin cured with an amine-POSS was studied using differential
scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The kinetic
of polymerization reaction and the thermal degradation have been analyzed
based on an iso-conversional model. The obtained results showed that the activation
energies of both processes depend on the degree of conversion.
Authors:J. Murillo-Hernández, S. López-Ramírez, J. Domínguez, C. Duran-Valencia, I. García-Cruz, and J. González-Guevara
A survey on the effect of ionic liquids (ILs) over the thermal stability of a heavy Mexican oil was performed. ILs used were
based on [Cnim]+ and [Cnpyr]+ organic cations with FeCl4− metal anion. Mixtures of heavy crude oil (HCO) with ILs show three oxidation zones: low temperature oxidation (LTO), full
deposition (FD) and high temperature oxidation (HTO). Thermal stability and mass loss decrease in the LTO zone but increase
in the FD and HTO zones for every ILs used. The activation energy of the oxidation is influenced by the ILs in the HTO zone.
It decreases when increasing the size of the organic radical substitute in the cation of the ILs while it increases with the
presence of hydroxyl groups. The influence of electronic structure and reactivity indexes are rationalized to understand the
variations of activation energy obtained of the reaction systems. Among all cations used, cation-3 (IL-3) shows the greater
value of HOMO-LUMO gap as well as the lower activation energy.
Authors:G. García-Rosales, E. Ordoñez-Regil, J. Ramírez Torres, J. López Monroy, M. Machain-Castillo, and L. Longoria-Gándara
This study deals with the characterization of a marine sediments profile from the Gulf of Tehuantepec, Mexico. Ten sediment
samples obtained from a core of 18.3 m of length were analysed. Although there have been numerous marine sediments studies
carried out in Mexico, more are needed to better understand the sea floor formation. Crystallographic, morphologic, physical,
chemical and gamma ray activity analysis were carried out on the samples. The analysis results showed a decrease in organic
matter content as a function of sea depth; this value is related to the specific surface area. Some hazardous materials as
Cr, Mn, Ni, Sr and Hg were also identified by PIXE in some samples, probably due to anthropogenic activity. The presence of
uranium a naturally occurring element was found in all the samples, suggesting a migration through all materials of strata,
radioactive elements such as 226Ra, 235U, 212Pb, 214Pb, 228Ac, 208Ti, 214Bi, 228Ac and 40K were detected.