Characterization of airborne particles in an open pit mining region.

We characterized airborne particle samples collected from 15 stations in operation since 2007 in one of the world's largest opencast coal mining regions. Using gravimetric, scanning electron microscopy (SEM-EDS), and X-ray photoelectron spectroscopy (XPS) analysis the samples were characterized in terms of concentration, morphology, particle size distribution (PSD), and elemental composition. All of the total suspended particulate (TSP) samples exhibited a log-normal PSD with a mean of d=5.46 ± 0.32 µm and σ(ln d)=0.61 ± 0.03. Similarly, all particles with an equivalent aerodynamic diameter less than 10 µm (PM(10)) exhibited a log-normal type distribution with a mean of d=3.6 ± 0.38 µm and σ(ln d)=0.55 ± 0.03. XPS analysis indicated that the main elements present in the particles were carbon, oxygen, potassium, and silicon with average mass concentrations of 41.5%, 34.7%, 11.6%, and 5.7% respectively. In SEM micrographs the particles appeared smooth-surfaced and irregular in shape, and tended to agglomerate. The particles were typically clay minerals, including limestone, calcite, quartz, and potassium feldspar.

Textural, structural and electrical properties of TiO2 nanoparticles using Brij 35 and P123 as surfactants.

The effect of the use of the triblock copolymer Pluronic P123[(PEO)20(PPO)70(PEO)20, Aldrich] and the non-ionic polyoxyethylene-lauryl ether Brij 35 as surfactants on the textural, structural and electrical properties of nanosized TiO2 is analyzed in this work. The as-obtained samples were thermally treated at 400 °C to eliminate the surfactant, promote dehydroxylation and crystallize the sample. The TiO2 samples were characterized by thermal analysis, N2 physisorption, x-ray diffraction analysis, micro-Raman spectroscopy and scanning electron microscopy. To evaluate the TiO2 electrical features, I-V data were obtained. The x-ray diffraction results show that in the chemical synthesis using surfactants, the crystallite size is smaller than that of the commercial sample. The Raman spectroscopy results clearly indicate that, when P123 is used, the anatase phase of TiO2 is obtained, whereas when Brij 35 is used a mixture of the anatase and brookite phases is obtained. The specific surface area and crystallite size of the TiO2 prepared as indicated above are higher and smaller, respectively, than the corresponding properties found in commercial TiO2. The I-V plot showed a nonlinear behavior of the nanosized TiO2. The samples obtained with P123 showed the best electrical conductivity.

Comportamiento del sulfato de magnesio durante la analgesia y anestesia - Hospital M. I. Los Mina; julio-octubre, 1989 / Behavior of the magnesium sulfate during analgesia and anaesthesia - Hospital M. I. Los Mina; July-October 1989

Con el objetivo de observar el comportamiento del sulfato de magnesio durante la analgesia y anestesia en pacientes preeclámpticas severas y eclámpticas, sometidas a operación cesárea en el Centro Materno Infantil San Lorenzo de Los Mina, Santo Domingo, República Dominicana, se realiza un estudio prospectivo longitudinal con las pacientes que asistieron a dicho centro del 1 de julio al 1 de octubre de 1989. La enfermedad hipertensiva del embarazo está representada en la investigación por un grupo de 79 mujeres preeclámpticas severas (96.1 por ciento ) y 2 de ellas eclámpticas (3.9 por ciento ). El grupo de edad estuvo representado por pacientes entre 16-25 años de edad. El tipo de anestesia mayormente utilizado fue el regional, en 64.7 por ciento . Los resultados pudieron comprobar que el sulfato de magnesio surte buen efecto durante la analgesia y la anestesia, en pacientes preeclámpticas severas y eclámpticas e relación con la disminución de la tensión arterial, la mejoría del dolor y los pocos efectos que produce en los recién nacidos