The Yellow Polymorphs of Mercuric Iodide (HgI2)

HgI₂ crystallizes under ambient conditions from various solvents and by sublimation into three concomitant polymorphs whose colors are red, orange, and yellow. The orange and yellow phases are metastable and transform into the red phase when touched. A phase transition from red to yellow occurs at 400 K. The reverse transition from yellow to red shows a huge hysteresis. We established that the structures of the metastable yellow^M phase (determined by single‐crystal X‐ray diffraction) and the high‐temperature yellow^HT phase (determined by powder synchrotron X‐ray diffraction and second‐harmonic generation) are different, albeit closely related. Both show analogous packings of I? Hg? I molecules, which are straight in the first and bent with an angle of ca. 160° in the second. The red and orange phases are tetrahedral semiconductor structures that sublime even at room temperature. The growth of the yellow^M phase from 2‐chloroethanol and the kinetics of the reconstructive phase transition red to yellow^HT and back were studied by optical microscopy, Raman spectroscopy in solution, luminescence, and powder synchrotron X‐ray diffraction as a function of time at various temperatures. Both yellow phases grow by accretion of HgI₂ molecules, present in the solution or liberated from the red crystals, on the surface of the crystal. In contrast, the reverse transformation from yellow to red occurs in the bulk of the crystal, presumably by migration of Hg in the packing of I and subsequent rearrangement of I. The displacement parameters of Hg in both structures are considerably larger than those of I and apparently not dominated by disorder effects.     

An amino acid based system for CO2 capture and catalytic utilization to produce formates

Herein, we report a novel amino acid based reaction system for CO₂ capture and utilization (CCU) to produce formates in the presence of the naturally occurring amino acid l-lysine. Utilizing a specific ruthenium-based catalyst system, hydrogenation of absorbed carbon dioxide occurs with high activity and excellent productivity. Noteworthy, following the CCU concept, CO₂ can be captured from ambient air in the form of carbamates and converted directly to formates in one-pot (TON > 50 000). This protocol opens new potential for transforming captured CO₂ from ambient air to C1-related products.

A novel amino acid based reaction system for CO₂ capture and utilization (CCU) to produce formates is presented applying a ruthenium-based catalyst. Noteworthy, CO₂ can be captured from ambient air and converted to formates in one-pot (TON > 50 000).     

Expedient protocol for solid-phase synthesis of secondary and tertiary amines

[reaction: see text] An expedient solid-phase synthetic approach to secondary and tertiary amines was developed. The protocol employs conversion of resin-bound amino alcohols to the corresponding iodides, followed by iodide displacement with primary or secondary amines or with unprotected amino alcohols. This two-step procedure, affording products in good to excellent yields, is suitable for solid-phase synthesis of polyamines.     

Proteome Analysis of Aflibercept Intervention in Experimental Central Retinal Vein Occlusion

Aflibercept is a frequently used inhibitor of vascular endothelial growth factor (VEGF) in the treatment of macular edema following central retinal vein occlusion (CRVO). Retinal proteome changes following aflibercept intervention in CRVO remain largely unstudied. Studying proteomic changes of aflibercept intervention may generate a better understanding of mechanisms of action and uncover aspects related to the safety profile. In 10 Danish Landrace pigs, CRVO was induced in both eyes with an argon laser. Right eyes were treated with intravitreal aflibercept while left control eyes received isotonic saline water. Retinal samples were collected 15 days after induced CRVO. Proteomic analysis by tandem mass tag-based mass spectrometry identified a total of 21 proteins that were changed in content following aflibercept intervention. In retinas treated with aflibercept, high levels of aflibercept components were reached, including the VEGF receptor-1 and VEGF receptor-2 domains. Fold changes in the additional proteins ranged between 0.70 and 1.19. Aflibercept intervention resulted in a downregulation of pigment epithelium-derived factor (PEDF) (fold change = 0.84) and endoplasmin (fold change = 0.91). The changes were slight and could thereby not be confirmed with less precise immunohistochemistry and Western blotting. Our data suggest that aflibercept had a narrow mechanism of action in the CRVO model. This may be an important observation in cases when macular edema secondary to CRVO is resistant to aflibercept intervention.     

Recrystallization of 223Ra with barium sulfate

In this work, the kinetics of barium sulfate recrystallization has been studied in acidic 0.01 mol dm^?3 sodium sulfate solution using ²²³Ra and ¹³³Ba tracers at very low total radium concentration, i.e. less than 10^?13 mol dm^?3. It was found that the system follows the homogeneous recrystallization model and that recrystallization rates, inferred by the decrease of ²²³Ra and ¹³³Ba in the aqueous solution, are fast. Therefore, even at very low concentrations, below the solubility limit, radium will be retained by barium sulfate—a mineral present in the deep underground repository.     

Graphene screen‐printed radio‐frequency identification devices on flexible substrates

Despite the great promise of printed flexible electronics from 2D crystals, and especially graphene, few scalable applications have been reported so far that can be termed roll‐to‐roll compatible. Here we combine screen printed graphene with photonic annealing to realize radio‐frequency identification devices with a reading range of up to 4 meters. Most notably our approach leads to fatigue resistant devices showing less than 1% deterioration of electrical properties after 1000 bending cycles. The bending fatigue resistance demonstrated on a variety of technologically relevant plastic and paper substrates renders the material highly suitable for various printable wearable devices, where repeatable dynamic bending stress is expected during usage. All applied printing and post‐processing methods are compatible with roll‐to‐roll manufacturing and temperature sensitive flexible substrates providing a platform for the scalable manufacturing of mechanically stable and environmentally friendly graphene printed electronics.

     

Influence of the steel powder type and processing parameters on the debinding of PM compacts with gelatin binder

Binders present an important part of the powder metallurgy technology as they are vital to provide efficient powder agglomeration and/or lubrication during shaping. At the same time, they have to be easily removed from the compacts during initial stages of sintering without any harmful effect for the base material, as well as for the environment. Therefore, behavior of gelatin as a binder for stainless- and tool-steel gas-atomised powder compacts was studied by thermal analysis and electron microscopy. Thermal analysis showed that peak mass-loss occurred in the range between 340 and 370 °C, depending on the base powder and heating rate. Risk for base powder oxidation at temperatures below 425 °C was detected. Based on the obtained results, it is recommended to perform debinding at ~425 °C after applying a heating rate of around 7.5 °C min^?1. Only in this way efficient enough binder removal can be obtained concurrently to avoiding base powder oxidation.     

Polyanionic Frameworks in the Lithium Phosphidogermanates Li2GeP2 and LiGe3P3 – Synthesis,Structure, and Lithium Ion Mobility

Recently fast lithium ion conductors were discovered in compounds containing tetrahedral SiP₄^8– and GeP₄^8– units. In the context of material development for all solid state batteries the ternary Li/Ge/P phase system has been further investigated and two new lithium phosphidogermanates were discovered on the lithium poor side of the ternary composition diagram. Li₂GeP₂ crystallizes in space group I4₁/acd with unit cell parameters of a = 12.3069(1) Å and c = 19.0306(4) Å, consists of a framework of Ge₄P₁₀ supratetrahedra, and exhibits an ionic conductivity of 1.5(3)×10^–7 S · cm^–1 at 27 °C. LiGe₃P₃ crystallizes in Pbam with a = 9.8459(5) Å, b = 15.7489(7) Å, and c = 3.5995(2) Å. In LiGe₃P₃ Ge and P atoms form a two dimensional polyanion. The slabs consist of five- and six-membered heteroatomic rings comprising GeP₄ and Ge(P₃Ge) tetrahedra including homoatomic Ge–Ge bonds. A semiconducting behavior with an electronic conductivity of ∼10^–4 S · cm^–1 and a remarkable stability vs. air and moisture is observed.