Medium modification of hadrons

I discuss pertinent aspects of the phase structure of strongly-interacting matter and their relation to the medium modifications of mesons. Special attention is paid to the critical endpoint in the phase diagram and the electromagnetic response in its vicinity.     

Expanded Prussian Blue Analogue Based on Octahedral {Nb<Subscript>6</Subscript>} Clusters and {K<Subscript>2</Subscript>} Dimers as Nodes

Abstract  The preparation, structures, and characterization of two new compounds containing octahedral niobium cyanochloride clusters as building units and (Et₄N)⁺ as cation are reported. The reaction between Nb₆Cl₁₄ · 8H₂O, KCN and (Et₄N)Cl led to the formation of (Et₄N)₄[Nb₆Cl₁₂(CN)₆] · 2.67H₂O (1) which crystallizes in triclinic P-1 space group (No. 2) with a = 12.552(2), b = 12.818(2), c = 12.919(2) ?, α = 105.157(3)°, β = 104.188(3)°, γ = 117.390(2)°, V = 1611.7(5) ?³ and Z = 1. 1 has a 2D hydrogen-bonded layer structure based on [Nb₆Cl₁₂(CN)₆]⁴⁻ units connected through hydrogen bonding between cyanide ligands and solvent water molecules. In the presence of large excess of K⁺ ions, similar reaction leads to formation of K₂(Et₄N)₂[Nb₆Cl₁₂(CN)₆] (2) which crystallizes in the tetragonal I4/m space group (No. 87) with a = b = 10.9597(3), c = 19.178(1) ?, V = 2303.6(2) ?³ and Z = 2. Its 3D structure is based on [Nb₆Cl₁₂]²⁺ and [K₂]²⁺ nodes bridged by cyanide ligands to form an expanded Prussian blue type framework with (Et₄N)⁺ acting as charge compensating ions. Index Abstract  An expanded Prussian blue type 3D framework based on hexanuclear {Nb₆} and dinuclear {K₂} units which are bridged by cyanide linker was synthesized and characterized. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Thin disk laser—Energy scaling

A time resolved numerical model of the interaction between pump absorption, excitation and amplified spontaneous emission (ASE) for the Thin Disk laser design was developed. The model accounts for the spectral distribution of the spontaneous emission, the spectral and spatial distribution of emission and absorption and the spectral and angular transmission of surfaces or coatings.     

Uniformization of {\mathcal {G}}-bundles

We show some of the conjectures of Pappas and Rapoport concerning the moduli stack Bun_G{{\rm Bun}_\mathcal {G}} of G{\mathcal {G}}-torsors on a curve C, where G{\mathcal {G}} is a semisimple Bruhat-Tits group scheme on C. In particular we prove the analog of the uniformization theorem of Drinfeld-Simpson in this setting. Furthermore we apply this to compute the connected components of these moduli stacks and to calculate the Picard group of Bun_G{{\rm Bun}_\mathcal {G}} in case G{\mathcal {G}} is simply connected.     

Investigation of chemical looping combustion of natural gas at 1 MWth scale

Chemical looping combustion (CLC) is an advanced oxyfuel process that enables CO₂ capture with low efficiency penalty. CLC of gaseous fuels has successfully been demonstrated in several pilots up to 150 kW_th. Numerous oxygen carriers have been tested regarding fuel conversion performance and lifetime. This work is a scale-up study of gaseous fuel CLC to MW_th scale. A Ca-Mn-based oxygen carrier has been developed and manufactured in ton-scale prior to the present test. Investigations were conducted in a 1 MW_th CLC unit that was adapted to utilize natural gas as fuel. Stable CLC conditions were reached during tests with Ca-Mn-based material, and the transition to operation with ilmenite was studied. The fuel conversion was in the range of 80%. During operation, 99% of the unburned methane was converted in the post oxidation chamber. The solids circulation rate and the lifetime of solids were determined by means of solids samples from the process, which were investigated in terms of attrition and degree of oxidation. The solids circulation rate was 17 tons h^?1  MW^?1 which is higher than in former tests but lower compared to other units. The most important limiting factors of the fuel conversion are the low solids inventory of the fuel reactor and the oxygen carrier to fuel ratio that corresponds to the solids circulation.     

Spontaneous Crystallization of Perovskite Nanocrystals in Nonpolar Organic Solvents: A Versatile Approach for their Shape‐Controlled Synthesis

The growing demand for perovskite nanocrystals (NCs) for various applications has stimulated the development of facile synthetic methods. Perovskite NCs have often been synthesized by either ligand‐assisted reprecipitation (LARP) at room temperature or by hot‐injection at high temperatures and inert atmosphere. However, the use of polar solvents in LARP affects their stability. Herein, we report on the spontaneous crystallization of perovskite NCs in nonpolar organic media at ambient conditions by simple mixing of precursor–ligand complexes without application of any external stimuli. The shape of the NCs can be controlled from nanocubes to nanoplatelets by varying the ratio of monovalent (e.g. formamidinium⁺ (FA⁺) and Cs⁺) to divalent (Pb²⁺) cation–ligand complexes. The precursor–ligand complexes are stable for months, and thus perovskite NCs can be readily prepared prior to use. Moreover, we show that this versatile synthetic process is scalable and generally applicable for perovskite NCs of different compositions.     

Microstructured switchable mirror for polar molecules

By miniaturizing electrode geometries high electric fields can be produced using modest voltages. A planar array of 20 microm wide gold electrodes, spaced 20 microm apart, is made on a sapphire substrate. A voltage difference of up to 350 V is applied to adjacent electrodes, generating an electric field that decreases exponentially with distance from the substrate. This microstructured array can be used as a mirror for polar molecules and can be rapidly switched on and off. This is demonstrated by retro-reflecting a beam of state-selected ammonia molecules with a forward velocity of about 30 m/s.