Characterizations of Schauder decompositions in Banach spaces

Acta Mathematica Hungarica -     

Mitsunobu dehydration of N-Boc neomycin B

Reaction of hexa-N-Boc neomycin B with TPP and DIAD in toluene results in the formation of an epoxide in ring IV, not an aziridine or azetidine as previously reported.     

A neutron powder diffraction study of the helimagnetic structure of TlCo2Se2−xSx

The magnetic layer structure of TlCo₂Se_2−xS_x has been thoroughly re-investigated with neutron powder diffraction. The cobalt magnetic moments are ferromagnetically arranged within the layers, but the interlayer coupling differs profoundly with varying composition (x): the spins in TlCo₂Se₂ form a helix along the c-axis with a turning-angle of ∼119° at 1.4 K. This kind of helical structure prevails for 0≤x≤1.5 with a gradual decrease of the angle with increasing sulphur content, down to 34°, showing an almost linear relationship with the interlayer distance of Co-Co. For x≥1.75 the interlayer coupling changes to ferromagnetic. Unexpectedly, two helices were found to coexist at x=0.5 and x=1.0. The interaction between adjacent cobalt layers is there characterized by an incommensurate angle (106°, resp., 73°) together with a commensurate angle of 90°. The magnetic structures have been refined as two magnetic phases, each having a characteristic wave vector. A tentative model where the symmetry of the structure and the interlayer distance compete is considered for explaining the simultaneous occurrence of the two kinds of diffraction profile satellites.     

Effect of Inoculated Lactic Acid Fermentation on the Fermentable Saccharides and Polyols,Polyphenols and Antioxidant Activity Changes in Wheat Sourdough

Inoculation of sourdough allows the fermentation medium to be dominated by desired microorganisms, which enables determining the kinetics of the conversion of chemical compounds by individual microorganisms. This knowledge may allow the design of functional food products with health features dedicated to consumers with special needs. The aim of the study was to assess the dynamics of transformations of fermentable oligosaccharide, disaccharide, monosaccharide and polyol (FODMAP) compounds from wheat flour as well as their antioxidant activity during inoculated and spontaneous sourdough fermentation. The FODMAP content in grain products was determined by the fructan content with negligible amounts of sugars and polyols. To produce a low-FODMAP cereal product, the fermentation time is essential. The 72 h fermentation time of L. plantarum-inoculated sourdough reduced the FODMAP content by 91%. The sourdough fermentation time of at least 72 h also positively influenced the content of polyphenols and antioxidant activity, regardless of the type of fermentation. The inoculation of both L. plantarum and L. casei contributed to a similar degree to the reduction in FODMAP in sourdough compared to spontaneous fermentation.     

Reversible Optical Writing and Data Storage in an Anthracene‐Loaded Metal–Organic Framework

Metal–organic frameworks (MOFs) enable the design of host–guest systems with specific properties. In this work, we show how the confinement of anthracene in a well‐chosen MOF host leads to reversible yellow‐to‐purple photoswitching of the fluorescence emission. This behavior has not been observed before for anthracene, either in pure form or adsorbed in other porous hosts. The photoresponse of the host–guest system is caused by the photodimerization of anthracene, which is greatly facilitated by the pore geometry, connectivity, and volume as well as the structural flexibility of the MOF host. The photoswitching behavior was used to fabricate photopatternable and erasable surfaces that, in combination with data encryption and decryption, hold promise in product authentication and secure communication applications.     

Evaluation of calcium carbonate in eggshells using thermal analysis

The eggshell of the hen is an important structure which provides protection for the developing chick, and also a container for the egg in the food industry. Egg breakage can reach up to 10% of total egg production, causing considerable economic losses. The eggshell consists of membranes, composed mainly of proteins, and the mineral shell composed mainly of the calcite polymorph of CaCO₃. The average CaCO₃ content of a chicken eggshell is between 93 and 97%, depending on animal genotype, age, housing system of laying hens and mineral nutrition. In the present study, eggs of the same breed and approximately same age were collected from four different production systems: organic farming, free-range production, deep litter system and battery cage system. The CaCO₃ content was determined by the standard titration method and by atomic absorption spectroscopy. Thermal properties of dried eggshell powder were measured by thermogravimetric measurements between 30 and 900 °C in air, showing a significant mass loss of?≈?43% between 600 and 850 °C corresponding to the decomposition of CaCO₃ to CaO and CO₂. The relations between the thermal mass loss and CaCO₃ content determined by the titration method/atomic absorption spectroscopy were studied using predictive models fitted by the linear regression method. A good prediction ability with an average prediction error of 0.01% was obtained between CaCO₃ determined by titration and the thermal mass loss, indicating that TG could provide a reliable method for evaluation of CaCO₃ content in eggshells.

     

Bis(perchlorocatecholato)silane—A Neutral Silicon Lewis Super Acid

No neutral silicon Lewis super acids are known to date. We report on the synthesis of bis(perchlorocatecholato)silane and verify its Lewis super acidity by computation (DLPNO‐CCSD(T)) and experiment (fluoride abstraction from SbF₆^?). The exceptional affinity towards donors is further demonstrated by, for example, the characterization of an unprecedented SiO₄F₂ dianion and applied in the first hydrodefluorination reaction catalyzed by a neutral silicon Lewis acid. Given the strength and convenient access to this new Lewis acid, versatile applications might be foreseen.     

An extraction system for low-energy hydrogen ions formed by electron impact

A system has been developed for extracting near-zero kinetic energy H⁻ and D⁻ ions formed by dissociative electron attachment. It is the essential part of a new set-up for vibrational spectroscopy of hydrogen molecules. A magnetic field is used to collimate the probing electron beam. Ions produced by electron collision with the target molecules are collected by the combined action of this field and an electrostatic field penetrating into the interaction region. Highly effective extraction is achieved by taking into account the correct out-of plane displacement of ion trajectories which is usually neglected in similar arrangements. The extraction conditions are mass dependent so that by proper tuning, mass selection of detected ions is achieved. The new system is also used for detecting positive ions created by electron collisions with hydrogen atoms and molecules.     

Crystal Structures of NbOI3 and NbOBr3 – Polar Double Chains in Different Non‐centrosymmetric Structures

NbOI₃ was obtained from a reaction of Nb₂O₅, Nb, and I₂. Single crystals free from disorder were a by‐product from a reaction with additional CsI. The monoclinic crystal structure (C2, a = 14.624(3) Å, b = 3.9905(8) Å, c = 12.602(3) Å, β = 120.4(3)°, Z = 4, R₁(F) = 0.0368, wR₂(F²) = 0.0804) represents a new structure type which is built up by distorted octahedral NbI₄O₂ with unequal O‐atoms in trans‐position. The octahedra are linked to dimers by a common edge of iodine atoms and to double chains by the apical oxygen atoms. A non‐centrosymmetric structure results because the short Nb–O distances point to the same direction and the polar double chains are parallel. The crystal structure of NbOBr₃ (NbOCl₃‐type, , a = 11.635(6) Å, c = 3.953(2) Å, R₁(F) = 0.082, wR₂(F²) = 0.174) shows the same polar double chains but the dimeric units Nb₂Br₆O₂ are orthogonal.     

Stability and interface quality of GeO2 films grown on Ge by atomic oxygen assisted deposition

The composition of GeO(2) films grown on Ge has been studied for different molecular deposition processes and after exposure to ambient air. The stoichiometry, the interaction with moisture, and the interfacial details of the films are shown to be dramatically process dependent.