Electro-oxidation of a cobalt based steel in LiOH: a non-noble metal based electro-catalyst suitable for durable water-splitting in an acidic milieu

The use of proton exchange membrane (PEM) electrolyzers is the method of choice for the conversion of solar energy when frequently occurring changes of the current load are an issue. However, this technique requires electrolytes with low pH. All oxygen evolving electrodes working durably and actively in acids contain IrO_x. Due to their scarcity and high acquisition costs, noble elements like Pt, Ru and Ir need to be replaced by earth abundant elements. We have evaluated a cobalt containing steel for use as an oxygen-forming electrode in H₂SO₄. We found that the dissolving of ingredients out of the steel electrode at oxidative potential in sulfuric acid, which is a well-known, serious issue, can be substantially reduced when the steel is electro-oxidized in LiOH prior to electrocatalysis. Under optimized synthesis conditions a cobalt-containing tool steel was rendered into a durable oxygen evolution reaction (OER) electrocatalyst (weight loss: 39 μg mm^-2 after 50 000 s of chronopotentiometry at pH 1) that exhibits overpotentials down to 574 mV at 10 mA cm^-2 current density at pH 1. Focused ion beam SEM (FIB-SEM) was successfully used to create a structure-stability relationship.

Oxidized Mild Steel S235: An Efficient Anode for Electrocatalytically Initiated Water Splitting

The surface of steel S235 was oxidized by Cl2 gas and checked for its electrocatalytic efficiency regarding oxygen formation in aqueous solution. If exposed to humid Cl2 gas for 110 min, steel S235 became an electrocatalyst that exhibits an overpotential for the oxygen evolution reaction (OER) of 462 mV at 1 mA cm(-2) at pH 7. The OER activity of the same sample at pH 13 was moderate (347 mV overpotential at 2.0 mA cm(-2) current density) in comparison with OER electrocatalysts developed recently. Potential versus time plots measured at a constant current demonstrate the sufficient stability of all samples under catalysis conditions at pH 7 and 13 for tens of hours. High-resolution X-ray photoelectron spectra could be reasonably resolved with the proviso that Fe2 O3 , FeO(OH), MnO(OH), and Mn2 O3 are the predominant Fe and Mn species on the surface of the oxidized steel S235.

Ultrafine sanding paper: a simple tool for creating small particles

A top-down approach, i.e., creating small particles by mechanical force starting from bulk materials, probably presents the most logical approach to particle size reduction and, therefore, top-down techniques are among the first to achieve small particles. A new solvent-free, amazingly simple approach is reported, suitable to achieve nanoparticles and sub-micro particles.

Organic melt, electride, and CVD induced in situ deposition of luminescent lanthanide imidazolate MOFs on nanostructured alumina

Highly luminescent MOF coatings were grown on nanostructured alumina membranes via melt, electride and CVD approaches.

Biomarker driven population enrichment for adaptive oncology trials with time to event endpoints

The development of molecularly targeted therapies for certain types of cancers has led to the consideration of population enrichment designs that explicitly factor in the possibility that the experimental compound might differentially benefit different biomarker subgroups. In such designs, enrollment would initially be open to a broad patient population with the option to restrict future enrollment, following an interim analysis, to only those biomarker subgroups that appeared to be benefiting from the experimental therapy. While this strategy could greatly improve the chances of success for the trial, it poses several statistical and logistical design challenges. Because late-stage oncology trials are typically event driven, one faces a complex trade-off between power, sample size, number of events, and study duration. This trade-off is further compounded by the importance of maintaining statistical independence of the data before and after the interim analysis and of optimizing the timing of the interim analysis. This paper presents statistical methodology that ensures strong control of type 1 error for such population enrichment designs, based on generalizations of the conditional error rate approach. The special difficulties encountered with time-to-event endpoints are addressed by our methods. The crucial role of simulation for guiding the choice of design parameters is emphasized. Although motivated by oncology, the methods are applicable as well to population enrichment designs in other therapeutic areas.

Coherent structural dynamics of a prototypical charge-density-wave-to-metal transition

Using femtosecond time-resolved x-ray diffraction, we directly monitor the coherent lattice dynamics through an ultrafast charge-density-wave-to-metal transition in the prototypical Peierls system K(0.3)MoO(3) over a wide range of relevant excitation fluences. While in the low fluence regime we directly follow the structural dynamics associated with the collective amplitude mode; for fluences above the melting threshold of the electronic density modulation we observe a transient recovery of the periodic lattice distortion. We can describe these structural dynamics as a motion along the coordinate of the Peierls distortion triggered by the prompt collapse of electronic order after photoexcitation. The results indicate that the dynamics of a structural symmetry-breaking transition are determined by a high-symmetry excited state potential energy surface distinct from that of the initial low-temperature state.

Die Struktur von SrCuSn2 und BaCuSn2 und ihre Verwandtschaft zum BiOCl-Gitter / The Structure of SrCuSn2 and BaCuSn2 and its Relationship to the BiOCl-Structure

The compounds SrCuSn2 and BaCuSn2 have been prepared and their crystal structures have been determined. They crystallize in a lattice (space-group Cmcm-D17 2h) related to that of the BiOCl-type.

Zur Struktur der Verbindung TlTe / On the Structure of TlTe

The crystal structure of TlTe was redetermined and by this way the Te-sublattice corrected. There are short Te-Te atomic distances which are comparable with covalent Te-Te bond distances.

Darstellung und Kristallstruktur des K2Sb4S7 / Preparation and Crystal Structure of K2Sb4S7

In the K2S/Sb2S3-System the compound K2Sb4S7 has been prepared and its structure determined. In this structure there are two differently coordinated Sb-atoms: the SbI-atoms in the vertices of flat SbS3-pyramides have the CN 3 to sulfur, the SbII-atoms are ψ-trigonal-bipyramidal coordinated with one free position in the equatorial plane. These polyhedra are connected to each other by common corners and edges to a three-dimensional net, which has channels parallel the b-axis, in which the K+-ions are located.

Die Kristallstrukturen der Verbindungen Ca5Si3 und Ca5Ge3 / The Crystal Structures of Ca5Si3 and Ca5Ge3

The new compounds Ca5Si3 and Ca5Ge3 were prepared and their structure determined.

They crystallize in the Cr5B3-structure type.

Zur Kenntnis einer neuen SrSi-Modifikation und der Phase SrGe0,76 / On a New SrSi-Modification and the New Compound SrGe0,76

A new SrSi-modification and the new phase SrGe0,76 were prepared and their structures determined. In these compounds the elementlVatoms form planar hexagons substituted in the 1, 2, 4, 5-positions by four additional Si(Ge)atoms. In the compound SrGe0,76 there are defects in this unit in the positions 1, 2, 4, 5, while in SrSi no indications of such defects could be found.