Advanced Nanostructured Conjugated Microporous Polymer Application in a Tandem Photoelectrochemical Cell for Hydrogen Evolution Reaction.

Solar energy conversion through photoelectrochemical cells by organic semiconductors is a hot topic that continues to grow due to the promising optoelectronic properties of this class of materials. In this sense, conjugated polymers have raised the interest of researchers due to their interesting light-harvesting properties. Besides, their extended π-conjugation provides them with an excellent charge conduction along the whole structure. In particular, conjugated porous polymers (CPPs) exhibit an inherent porosity and three-dimensional structure, offering greater surface area, and higher photochemical and mechanical stability than their linear relatives (conjugated polymers, CPs). However, CPP synthesis generally provides large particle powders unsuitable for thin film preparation, limiting its application in optoelectronic devices. Here, a synthetic strategy is presented to prepare nanostructures of a CPP suitable to be used as photoelectrode in a photoelectrochemical (PEC) cell. In this way, electronic and photoelectrochemical properties are measured and, attending to the optoelectronic properties, two hybrid photoelectrodes (photoanode and photocathode) are designed and built to assemble a tandem PEC cell. The final device exhibits photocurrents of 0.5 mA cm-2 at a 0.7 V in the two electrode configuration and the hydrogen evolution reaction is observed and quantified by gas chromatography, achieving 581 µmol of H2 in a one-hour reaction.

Infografías en las ciencias de la salud: aplicación en las enfermedades de transmisión sexual / Infographics in the health sciences: application to the sexually transmitted diseases

OBJETIVO: Describir las infografías sobre las enfermedades de transmisión sexual (ETS) recuperadas mediante Google Images® y analizar su información y posibilidades de uso. MÉTODO: Estudio descriptivo transversal. Las infografías se obtuvieron mediante búsqueda con los términos «infographic», «sexually transmitted diseases» y «sexually transmitted infections». Para seleccionar las imágenes a estudio se calculó el tamaño muestral mediante la estimación de parámetros poblacionales en una población infinita. La fecha de la búsqueda fue el 15 de marzo de 2018. RESULTADOS: Se seleccionaron 386 infografías para cada término (diseases/infections), descartándose 198 (20,4%) imágenes por ruido documental; 718 infográfias (99,5%) tenían carácter informativo. La mayoría provenían de Blogs personales, 129 (16,7%) o de persona individual, 54 (7,0%). Presentaron algún tipo de licencia 31 (4,0%) infografías. Más de la mitad (Mediana = 0,4 Mpx) de las imágenes analizadas presentaron adecuada resolución. CONCLUSIONES: Se consiguió recuperar infografías sobre ETS, en su mayoría eran de tipo informativo, pero con un alto "ruido documental". Se observó una baja filiación institucional de estas imágenes que tampoco disponían de un conveniente uso de licencias Creative Commons, no obstante, existió una buena resolución de imagen

OBJECTIVE: To describe the infographics on sexually transmitted diseases (STDs) recovered through Google Images® and analyze their information and possibilities of use. METHODS: Cross-sectional descriptive study. The infographics were obtained by searching with the terms "infographic", "sexually transmitted diseases" and "sexually transmitted infections". To select the images for the study, a sample size was calculated by estimating parameters in an infinite population. The date of the search was 15 of March 2018. RESULTS: 386 infographics were selected for each term (diseases/infections), discarding 198 (20.4%) images due to documentary noise; 718 infographics (99.5%) were informative. Most of them, came from personal blogs, 129 (16.7%) or individual, 54 (7.0%). They presented some type of license 31 (4.0%) infographics. More than half (Median = 0.4 Mpx) of the analyzed images presented adequate resolution. CONCLUSIONS: It was possible to recover infographics about STDs but with a high "documentary noise" that was mostly informative. There was a low institutional affiliation of these images that did not have a convenient use of Creative Commons licenses, although most of them presented a good image resolution

Fundamental Insights into Photoelectrocatalytic Hydrogen Production with a Hole-Transport Bismuth Metal-Organic Framework.

Solar fuels production is a cornerstone in the development of emerging sustainable energy conversion and storage technologies. Light-induced H2 production from water represents one of the most crucial challenges to produce renewable fuel. Metal-organic frameworks (MOFs) are being investigated in this process, due to the ability to assemble new structures with the use of suitable photoactive building blocks. However, the identification of the reaction intermediates remains elusive, having negative impacts in the design of more efficient materials. Here, we report the synthesis and characterization of a new MOF prepared with the use of bismuth and dithieno[3,2-b:2',3'-d]thiophene-2,6-dicarboxylic acid (DTTDC), an electron-rich linker with hole transport ability. By combining theoretical studies and time-resolved spectroscopies, such as core hole clock and laser flash photolysis measurements, we have completed a comprehensive study at different time scales (fs to ms) to determine the effect of competitive reactions on the overall H2 production. We detect the formation of an intermediate radical anion upon reaction of photogenerated holes with an electron donor, which plays a key role in the photoelectrocatalytic processes. These results shed new light on the use of MOFs for solar fuel production.

Hydroxamate Titanium-Organic Frameworks and the Effect of Siderophore-Type Linkers over Their Photocatalytic Activity.

The chemistry of metal-organic frameworks (MOFs) relies on the controlled linking of organic molecules and inorganic secondary building units to assemble an unlimited number of reticular frameworks. However, the design of porous solids with chemical stability still remains limited to carboxylate or azolate groups. There is a timely opportunity to develop new synthetic platforms that make use of unexplored metal binding groups to produce metal-linker joints with hydrolytic stability. Living organisms use siderophores (iron carriers in Greek) to effectively assimilate iron in soluble form. These compounds make use of hard oxo donors as hydroxamate or catecholate groups to coordinate metal Lewis acids such as iron, aluminum, or titanium to form metal complexes very stable in water. Inspired by the chemistry of these microorganisms, we report the first hydroxamate MOF prepared by direct synthesis. MUV-11 (MUV = materials of Universidad de Valencia) is a crystalline, porous material (close to 800 m2·g-1) that combines photoactivity with good chemical stability in acid conditions. By using a high-throughput approach, we also demonstrate that this new chemistry is compatible with the formation of single-crystalline phases for multiple titanium salts, thus expanding the scope of accessible precursors. Titanium frameworks are regarded as promising materials for photocatalytic applications. Our photoelectrochemical and catalytic tests suggest important differences for MUV-11. Compared to other Ti-MOFs, changes in the photoelectrochemical and photocatalytic activity have been rationalized with computational modeling, revealing how the chemistry of siderophores can introduce changes to the electronic structure of the frontier orbitals, relevant to the photocatalytic activity of these solids.

A Facile Synthesis of Blue Luminescent [7]Helicenocarbazoles Based on Gold-Catalyzed Rearrangement-Iodonium Migration and Suzuki-Miyaura Benzannulation Reactions.

New azahelicenes having interesting photophysical properties have been prepared in a four-step sequence. These [7]helicenocarbazoles are efficient blue luminophores, demonstrating the utility of gold catalysis in the preparation of advanced materials.

A Polymerization-Associated Structural Switch in FtsZ That Enables Treadmilling of Model Filaments.

Bacterial cell division in many organisms involves a constricting cytokinetic ring that is orchestrated by the tubulin-like protein FtsZ. FtsZ forms dynamic filaments close to the membrane at the site of division that have recently been shown to treadmill around the division ring, guiding septal wall synthesis. Here, using X-ray crystallography of Staphylococcus aureus FtsZ (SaFtsZ), we reveal how an FtsZ can adopt two functionally distinct conformations, open and closed. The open form is found in SaFtsZ filaments formed in crystals and also in soluble filaments of Escherichia coli FtsZ as deduced by electron cryomicroscopy. The closed form is found within several crystal forms of two nonpolymerizing SaFtsZ mutants and corresponds to many previous FtsZ structures from other organisms. We argue that FtsZ's conformational switch is polymerization-associated, driven by the formation of the longitudinal intersubunit interfaces along the filament. We show that such a switch provides explanations for both how treadmilling may occur within a single-stranded filament and why filament assembly is cooperative.IMPORTANCE The FtsZ protein is a key molecule during bacterial cell division. FtsZ forms filaments that organize cell membrane constriction, as well as remodeling of the cell wall, to divide cells. FtsZ functions through nucleotide-driven filament dynamics that are poorly understood at the molecular level. In particular, mechanisms for cooperative assembly (nonlinear dependency on concentration) and treadmilling (preferential growth at one filament end and loss at the other) have remained elusive. Here, we show that most likely all FtsZ proteins have two distinct conformations, a "closed" form in monomeric FtsZ and an "open" form in filaments. The conformational switch that occurs upon polymerization explains cooperativity and, in concert with polymerization-dependent nucleotide hydrolysis, efficient treadmilling of FtsZ polymers.