Understanding solid-gas reaction mechanisms by operando soft X-ray absorption spectroscopy at ambient pressure

Ambient-pressure operando soft X-ray absorption spectroscopy (soft-XAS) was applied to study the reactivity of hydroxylated SnO2 nanoparticles toward reducing gases. H2 was first used as a test case, showing that the gas phase and surface states can be simultaneously probed: Soft-XAS at the O K-edge gains sensitivity toward the gas phase, while at the Sn M4,5-edges, tin surface states are explicitly probed. Results obtained by flowing hydrocarbons (CH4 and CH3CHCH2) unequivocally show that these gases react with surface hydroxyl groups to produce water without producing carbon oxides and release electrons that localize on Sn to eventually form SnO. The partially reduced SnO2 – x layer at the surface of SnO2 is readily reoxidized to SnO2 by treating the sample with O2 at mild temperatures (>200 °C), revealing the nature of “electron sponge” of tin oxide. The experiments, combined with DFT calculations, allowed devising of a mechanism for dissociative hydrocarbon adsorption on SnO2, involving direct reduction of Sn sites at the surface via cleavage of C–H bonds and the formation of methoxy- and/or methyl-tin species at the surface

Effects of Dopant Ionic Radius on Cerium Reduction in Epitaxial Cerium Oxide Thin Films

The role of trivalent rare-earth dopants on the cerium oxidation state has been systematically studied by in situ photoemission spectroscopy with synchrotron radiation for 10 mol % rare-earth doped epitaxial ceria films. It was found that dopant rare-earths with smaller ionic radius foster the formation of Ce³⁺ by releasing the stress strength induced by the cation substitution. With a decrease of the dopant ionic radius from La³⁺ to Yb³⁺, the out-of-plane axis parameter of the crystal lattice decreases without introducing macroscopic defects. The high crystal quality of our films allowed us to comparatively study both the ionic conductivity and surface reactivity ruling out the influence of structural defects. The measured increase in the activation energy of films and their enhanced surface reactivity can be explained in terms of the dopant ionic radius effects on the Ce⁴⁺ → Ce³⁺ reduction as a result of lattice relaxation. Such findings open new perspectives in designing ceria-based materials with tailored properties by choosing suitable cation substitution

Outcomes of minimally invasive simple prostatectomy for benign prostatic hyperplasia: a systematic review and meta-analysis.

PURPOSE: (1) To assess the outcomes of minimally invasive simple prostatectomy (MISP) for the treatment of symptomatic benign prostatic hyperplasia in men with large prostates and (2) to compare them with open simple prostatectomy (OSP). METHODS: A systematic review of outcomes of MISP for benign prostatic hyperplasia with meta-analysis was conducted. The article selection process was conducted according to the PRISMA guidelines. RESULTS: Twenty-seven observational studies with 764 patients were analyzed. The mean prostate volume was 113.5 ml (95 % CI 106-121). The mean increase in Qmax was 14.3 ml/s (95 % CI 13.1-15.6), and the mean improvement in IPSS was 17.2 (95 % CI 15.2-19.2). Mean duration of operation was 141 min (95 % CI 124-159), and the mean intraoperative blood loss was 284 ml (95 % CI 243-325). One hundred and four patients (13.6 %) developed a surgical complication. In comparative studies, length of hospital stay (WMD -1.6 days, p = 0.02), length of catheter use (WMD -1.3 days, p = 0.04) and estimated blood loss (WMD -187 ml, p = 0.015) were significantly lower in the MISP group, while the duration of operation was longer than in OSP (WMD 37.8 min, p < 0.0001). There were no differences in improvements in Qmax, IPSS and perioperative complications between both procedures. The small study sizes, publication bias, lack of systematic complication reporting and short follow-up are limitations. CONCLUSIONS: MISP seems an effective and safe treatment option. It provides similar improvements in Qmax and IPSS as OSP. Despite taking longer, it results in less blood loss and shorter hospital stay. Prospective randomized studies comparing OSP, MISP and laser enucleation are needed to define the standard surgical treatment for large prostates

Promoción racional de medicamentos, una necesidad de estos tiempos

La promoción de medicamentos ha constituido un tema de reflexión para aquellos que integran la llamada cadena del medicamento (productor, prescriptor, dispensador y consumidor), si se analiza desde la arista que representan sus intereses. En este trabajo se presentan las principales causas que influyen al hacer uso de los medicamentos, en general, y se destaca las características particulares de la promoción cubana de medicamentos, provocando que se diferencie de lo que sucede en el mundo contemporáneo en esta materia y constituya una herramienta para mantener los logros alcanzados en la calidad de la terapéutica.<br>Drug promotion has been a topic of reflexion for those being part of the so-called drug chain (manufacturer, prescriber, dispenser and consumer), if it is analyzed from the point of view of their interests. The main causes influencing on the use of drugs in general are presented in this paper. Emphasis is made on the particular characteristics of the Cuban drug promotion, which differs from what happens in this sphere in today's world and is a tool to maintain the achievements attained in the quality of therapeutics