Hydrogen adsorption on lithium clusters coordinated to a gC3N4 cavity.

The search of new materials having suitable characteristics to trap hydrogen for fuel applications is greatly challenging due to the stringent requirements that such materials must meet. In this sense, with the aid of computational chemistry, significant advances can be achieved. The present work explores the adsorption of hydrogen molecules by lithium clusters (Lin, where n = 1-6) coordinated to a graphitic carbon nitride (heptazine, gC3N4) cavity. The study was conducted using the density functional theory (M06-2X-D3) in combination with the def2-TZVP basis set. Our results suggest that lithium atoms in the gC3N4-cavity can coordinate up to 10 hydrogen molecules with bond energies in the range -0.10 to -0.19 eV. The [gC3N4Li5]+ and [gC3N4Li6] systems resulted to be the most promising in terms of lithium coordination. They feature the highest stabilization energies for hydrogen adsorption. According to the calculated Gibbs free energies for these systems, H2 adsorption remains a spontaneous process even at 400 K.

Tissue spinal cord response in rats after implants of polypyrrole and polyethylene glycol obtained by plasma.

Most of the biomaterials used nowadays for the reconstruction of the spinal cord (SC) tissue after an injury, tested in animals, have obtained modest results. This work presents a study about the compatibility of two novel, non-biodegradable, semi-conductive materials, obtained by plasma polymerization: iodine-doped pyrrole (PPy/I) and pyrrole-polyethylene glycol (PPy/PEG). Both polymers, separately, were implanted in the SC tissue of rats after a transection. Prior to implantation, the elemental composition and the physico-chemical properties of polymers were studied by electron scanning microscopy, IR Spectroscopy and thermogravimetric analysis. We used adult female Long Evans rats, subjected to SC transection. Animals were randomized to be allocated in one of the treatment groups and were killed four weeks after the lesion for histology study. Results showed that both implants were integrated to the SC tissue, as inflammatory and gliotic responses, similar to those observed in the control group, and rejection of the implant, were not evident. Moreover, the immediate effect of PPy/I or PPy/PEG in the injured SC prevented secondary tissue destruction, as compared to non-implanted control animals. In conclusion, implants of semi-conductive polymers were well-tolerated and integrated favorably to SC tissue after transection.

Fístula colovesical por enfermedad diverticular del colon. Informe de un caso / Colovesical fistula in diverticular colon disease. A case report

La fístula colovesical es una complicación poco frecuente de la enfermedad diverticular del colon, así como de malignidades pélvicas, radiaciones pélvicas o trauma. El diagnóstico temprano de la fístula colovesical es difícil así como su manejo, la fístula colovesical puede diagnosticarse cuando se presenta patología colónica pero los síntomas presentes sugieren un problema del tracto urinario, estos son relacionados con infecciones urinarias bajas persistentes pero complicaciones como la pielonefritis puede ocurrir. Presentamos el caso de un paciente diabético de 52 años de edad descontrolado con infecciones urinarias bajas repetitivas de difícil control sin síntomas intestinales, manifestado por neumaturia y fecaluria diagnosticándose clínicamente y corroborándose por el colon por enema y tomografía de abdomen, tratándose mediante intervención quirúrgica con la resección de la fístula, con cierre primario de la vejiga y resección de sigmoides con anastomosis termino terminal colorrectal, el paciente evoluciona satisfactoriamente sin complicaciones. Se revisa la literatura y se hacen algunas consideraciones.