Tailoring the magnetic properties of FexCo(1-x) nanopowders prepared by a polyol process.

Precise control over the magnetic properties of FeCo alloys is of scientific significance, due to their high Curie points and saturation magnetizations, and of broad interest for applications such as transformer cores, induction motors, switching devices, and hyperthermia. The magnetic properties of FexCo(1-x) alloy-based nanopowders prepared by polyol synthesis and their relationship with morphological features and the evolution of the microstructure were investigated using a design of experiments (DoE) approach. Proportionalities related to the magnetic properties, saturation magnetization (Ms) and coercivity (Hc), were identified where Ms ∝ (110) crystallite size of FeCo (bcc) and Hc ∝ particle diameter for the as-synthesized FexCo(1-x) nanopowders. Adjusting the reaction composition allows for control of the FeCo (bcc) (110) crystallite size from 20-45 nm represented by a response surface model. Morphological features of the as-synthesized nanopowders include particles interlinked as chains, and particles either in the form of cuboids or spheroids, all with diameters ranging from 75-175 nm. FexCo(1-x) alloy was confirmed by XRD in each nanopowder while few contained a combination of phases which include Co (fcc), or ferrite (CoFe2O4), or both. Depending on composition, particle dimension, and microstructure, the Ms ranged from 90-215 emu g-1 with Hc from 90-400 Oe for all nanopowders synthesized by the sub-reflux, isothermal condition (150 °C). Tailoring the magnetic properties of FexCo(1-x) alloy-based nanopowders is accomplished chemically by identifying and regulating significant reaction parameters and conditions.

Prevalencia de parásitos intestinales en habitantes de una comunidad rural del estado Bolívar, Venezuela / Prevalence of Intestinal Parasites in Residents from a Rural Community in the State of Bolivar, Venezuela

Determinar la prevalencia de parásitos intestinales en una muestra de habitantes de la comunidad rural “La Carolina” del estado Bolívar, Venezuela. Materiales y Métodos: Una muestra fecal de cada habitante participante fue analizada mediante las técnicas de examen directo, Kato, Sedimentación Espontánea y coloración de Kinyoun. Resultados: De los 115 habitantes evaluados, 97 resultaron parasitados para una prevalencia de 84,3%. Con relación a la edad, todos los grupos fueron afectados por igual ( =0,812 g.l.: 6 p>0,05) aunque la mayor cantidad de casos (52 habitantes) se encontraron en el grupo de 0-9 años. Ambos sexos fueron afectados por igual (p>0,05). Se encontró 54,6% de poliparasismo y 45,4% de monoparasitismo. Nueve especies de enteroparásitos fueron diagnosticados, siendo el grupo de los chromistas y protozoarios más prevalentes (94,8%) que los helmintos. Blastocystis spp. fue el parásito más prevalente con 65,2%. No se diagnosticaron coccidios intestinales. Las asociaciones parasitarias más comunes fueron entre protozoarios, destacándose la de Blastocystis spp con Giardia intestinalis (22,6%) y Blastocystis spp. con Endolimax nana (15,1%). Conclusión: Se determinó una importante prevalencia de parásitos intestinales (84,3%) en la comunidad rural “La Carolina” del estado Bolívar, Venezuela.

To determine the prevalence of intestinal parasites in a sample of residents from the rural community, “La Carolina,” in the State of Bolivar, Venezuela. Material and Methods: A fecal sample from each participating inhabitant was analyzed using techniques of direct examination, Kato, spontaneous sedimentation and Kinyoun staining. Of the 115 people tested, 97 were parasitized with a prevalence of 84.3 %. With regard to age, all groups were affected equally (² = 0.812 df: 6 p > 0.05), although the largest number of cases (52 people) were found in the group of 0-9 years. Both sexes were equally affected (p> 0.05). The study found 54.6% polyparasitism and 45.4% monoparasitism. Nine species of intestinal parasites were diagnosed. The group of protozoa and chromists were more prevalent (94.8%) than helminths. Blastocystis spp. was the most prevalent parasite with 65.2 %. No intestinal coccidia were diagnosed. The most common parasitic associations were between protozoa, emphasizing Blastocystis spp. with Giardia intestinalis (22.6%) and Blastocystis spp. with Endolimax nana (15.1%). An important prevalence of intestinal parasites (84.3%) was determined in the rural community, “La Carolina,” State of Bolivar.