Hematite photoelectrodes grown on porous CuO–Sb₂O₅–SnO₂ ceramics for photoelectrochemical water splitting

Photoelectrodes capable of cost-effective hydrogen production on a large scale, via photoelectrochemical water splitting under solar light, could offer an elegant solution to many current problems of humankind caused by over-reliance on fossil fuels and the resulting environmental pollution. The search and design of low-cost photoelectrode materials and substrates for practical applications are required. In this work, unmodified hematite photoanodes grown by metal-organic chemical vapor deposition (MO-CVD) onto CuO–Sb2O5–SnO2 ceramic substrates are reported. The deposition time of hematite precursor varied between 10 min, 60 min, and 90 min. The photoanode grown for 60 min exhibits the highest photocurrent density recorded at 1.23 V vs RHE (reversible hydrogen electrode): 4.79 mA/cm2 under blue light of Thorlabs LED M455L2 (455 nm), 0.41 mA/cm2 under the radiation of the real sun in Mexico, and 0.38 mA/cm2 under AM1.5G solar simulator conditions. The high porosity of CuO–Sb2O5–SnO2 ceramics permits the permeation of the hematite precursor into the substrate bulk, which results in 3D-growth of a thin Fe2O3-coating (50 nm or less) on conductive SnO2-grains in the ceramics to a depth of ca. 5 μm. The thick photocatalytic layer (SnO2-grains coated by hematite) of several micrometers assures a good light harvesting by the photoelectrode, while the nano-sized Fe2O3-films on conductive SnO2-grains is favorable for charge diffusion. This architecture of the photoelectrode results in good photoelectrochemical characteristics and is promising for further development.</p

Vacuum-annealing induces sub-surface redox-states in surfactant-structured α-Fe₂O₃ photoanodes prepared by ink-jet printing

Transparent nano-structured hematite (α-Fe2O3) films of approximately 550 nm thickness on tin-doped indium oxide (ITO) have been obtained conveniently by ink-jet printing of a Fe(NO3)3/Brij® O10 precursor ink and subsequent annealing at 500 °C in air. When illuminated with a blue LED (λ = 455 nm, ca. 100 mW cm−2), the hematite films exhibited photocurrents of up to 70 μA cm−2 at 0.4 V vs. SCE in 0.1 M NaOH electrolyte. Thermal annealing in vacuum at 500 °C for 2 h increased photocurrents more than three times to 230 μA cm−2 in agreement with previous literature reports for pure hematite materials. These results suggest that a simple ink-jetting process with surfactants is viable. The effects of vacuum-annealing on the photoelectrical properties of α-Fe2O3 films are discussed in terms of a sub-surface state templating hypothesis based on data gathered from photo-transients, field emission scanning electron microscopy, X-ray photoelectron spectroscopy analysis, X-ray diffraction, photocurrent spectra, and cyclic voltammetry

A restriction site to differentiate Plasmodium and Haemoproteus infections in birds: on the inefficiency of general primers for detection of mixed infections

Avian Plasmodium and Haemoproteus parasites are easily detected by DNA analyses of infected samples but only correctly assigned to each genus by sequencing and use of a phylogenetic approach. Here, we present a restriction site to differentiate between both parasite genera avoiding the use of those analyses. Alignments of 820 sequences currently listed in GenBank encoding a particular cytochrome B region of avian Plasmodium and Haemoproteus show a shared restriction site for both genera using the endonuclease Hpy CH4III. An additional restriction site is present in Plasmodium sequences that would initially allow differentiation of both genera by differential migration of digested products on gels. Overall 9 out of 326 sequences containing both potential restriction sites do not fit to the general rule. We used this differentiation of parasite genera based on Hpy CH4III restriction sites to evaluate the efficacy of 2 sets of general primers in detecting mixed infections. To do so, we used samples from hosts infected by parasites of both genera. The use of general primers was only able to detect 25 % or less of the mixed infections. Therefore, parasite DNA amplification using general primers to determine the species composition of haemosporidian infections in individual hosts is not recommended. Specific primers for each species and study area should be designed until a new method can efficiently discriminate both parasites.Peer reviewe

Porous and conductive SnO2 ceramics as a promising nanostructured substrate to host photocatalytic hematite coatings: Towards low cost solar-driven water splitting

Commercially viable generation of “green” hydrogen fuel by solar-driven water splitting requires the design of low-cost photoelectrodes and photo-devices with high photoelectrochemical performance. In this regard, conductive and easily fabricated 3D-oxide ceramics with nanosized grains and high porosity are promising as a substrate with a large surface area to host photocatalytic coatings. To test this approach, hematite photoelectrodes have been grown by metal-organic chemical vapor deposition onto free-standing SnO2-based ceramics. The photoanodes formed onto Sb2O5-SnO2, CuO-Sb2O5-SnO2, and on MoO3-Sb2O5-SnO2 substrates in aqueous 1 M NaOH under 1 sun irradiation exhibit photocurrent densities of 0.44 mA/cm2, 0.56 mA/cm2, and 0.39 mA/cm2 at 1.23 V vs. RHE, respectively. The porosity of ceramics results in the 3D growth of a thin hematite coating on ceramic grains in the substrate to a depth of ca. 3 μm. The obtained photoelectrodes are discussed based on the data of photoelectrochemical measurements, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Raman spectroscopy. Routes to improved performance are discussed

MgO refractory doped with ZrO2 nanoparticles: Influence of cold isostatic and uniaxial pressing and sintering temperature in the physical and chemical properties

The chemical environment and the internal conditions of the furnaces and ladles are extremely aggressive for the refractories, so metallurgical industries demand refractory linings with greater durability and resistance to avoid unforeseen stoppages and to reduce the changes of the furnace lining. Therefore, the current work aims to evaluate the impact of the additions of ZrO2-nanoparticles (1, 3, and 5 wt. %) in magnesia-based bricks. A comparative study of the physical and chemical properties in bricks obtained using two cold pressing techniques (uniaxial and isostatic pressing) and two sintering temperatures (1550 and 1650 &deg;C) was carried out. The microstructure and crystalline phase characteristics obtained after the heat treatments and the slag corrosion test was studied using scanning electron microscopy/electron dispersive X-ray spectroscopy (SEM/EDX) and X-ray diffraction (XRD). The results reveal that the sample with 5 wt. % of ZrO2 nanoparticles (obtained by cold isostatic pressing and sintering at 1650 &deg;C) has the lowest porosity and greatest resistance to penetration of blast furnace slag

Hematite photoelectrodes grown on porous CuO–Sb₂O₅–SnO₂ ceramics for photoelectrochemical water splitting

Photoelectrodes capable of cost-effective hydrogen production on a large scale, via photoelectrochemical water splitting under solar light, could offer an elegant solution to many current problems of humankind caused by over-reliance on fossil fuels and the resulting environmental pollution. The search and design of low-cost photoelectrode materials and substrates for practical applications are required. In this work, unmodified hematite photoanodes grown by metal-organic chemical vapor deposition (MO-CVD) onto CuO–Sb2O5–SnO2 ceramic substrates are reported. The deposition time of hematite precursor varied between 10 min, 60 min, and 90 min. The photoanode grown for 60 min exhibits the highest photocurrent density recorded at 1.23 V vs RHE (reversible hydrogen electrode): 4.79 mA/cm2 under blue light of Thorlabs LED M455L2 (455 nm), 0.41 mA/cm2 under the radiation of the real sun in Mexico, and 0.38 mA/cm2 under AM1.5G solar simulator conditions. The high porosity of CuO–Sb2O5–SnO2 ceramics permits the permeation of the hematite precursor into the substrate bulk, which results in 3D-growth of a thin Fe2O3-coating (50 nm or less) on conductive SnO2-grains in the ceramics to a depth of ca. 5 μm. The thick photocatalytic layer (SnO2-grains coated by hematite) of several micrometers assures a good light harvesting by the photoelectrode, while the nano-sized Fe2O3-films on conductive SnO2-grains is favorable for charge diffusion. This architecture of the photoelectrode results in good photoelectrochemical characteristics and is promising for further development.</p

Primer consenso interinstitucional de neoplasias mieloproliferativas crónicas

Objetivo: El objetivo del consenso es poner a disposición de los profesionales de las diferentes instituciones de salud pública en nuestro país, quienes se encuentran a cargo de estas enfermedades, la información más relevante y actualizada acerca de su diagnóstico y tratamiento en la práctica clínica. Con este consenso interinstitucional esperamos contribuir a mejorar la calidad de la atención de los pacientes con neoplasias mieloproliferativas crónicas a todo lo ancho y largo de la República Mexicana, con el fin de unificar criterios tanto en diagnóstico como en tratamiento de las diferentes enfermedades mieloproliferativas

Riesgo en los procedimientos invasivos

Los pacientes con neoplasias mieloproliferativas tienen un riesgo incrementado de trombosis y sangrado. Se debe identificar dicho riesgo, así como individualizar la estrategia terapéutica previo a los procedimientos invasivos; una adecuada citorreducción disminuye el riesgo de complicaciones

Trasplante de progenitores hematopoyéticos en la mielofibrosis

El objetivo de este trabajo es generar recomendaciones sobre el manejo del trasplante alogénico de células madre (alo-SCT) en la mielofibrosis primaria (MFP). Se utilizó una revisión sistemática integral de artículos publicados entre 1999 y 2015 (enero) como fuente de evidencia científica. Las recomendaciones se produjeron mediante un proceso Delphi en el que participó un panel de 23 expertos designados por la European LeukemiaNet y el European Blood and Marrow Transplantation Group. Las preguntas clave incluyeron la selección de pacientes, la selección de donantes, el manejo previo al trasplante, el régimen de acondicionamiento, el manejo posterior al trasplante, la prevención y el manejo de la recaída después del trasplante. Los pacientes con enfermedad de riesgo intermedio 2 o alto y edad 2%, o citogenética adversa. La esplenectomía previa al trasplante debe decidirse caso por caso. Los pacientes con enfermedad de riesgo intermedio 2 o alto que carecen de un hermano compatible con el antígeno leucocitario humano (HLA) o de un donante no emparentado deben inscribirse en un protocolo que utilice donantes no idénticos de HLA. PB se consideró la fuente más apropiada de células madre hematopoyéticas para trasplantes de hermanos y donantes no emparentados compatibles con HLA. La intensidad óptima del régimen de acondicionamiento aún debe definirse. Se consideraron adecuadas estrategias como la suspensión de los fármacos inmunosupresores, la infusión de linfocitos del donante o ambas para evitar la recaída clínica. En conclusión, proporcionamos recomendaciones basadas en consenso destinadas a optimizar el alo-SCT en MFP. Se destacaron las necesidades clínicas insatisfechas