On the Schröder-Bernstein problem for carathéodory vector lattices

In this note we prove that there exists a Carathéodory vector lattice V such that V ≌ V ³ and V ?V ². This yields that V is a solution of the Schröder-Bernstein problem for Carathéodory vector lattices. We also show that no Carathéodory Banach lattice is a solution of the Schröder-Bernstein problem.     

Differentiation of fluoronitroaniline isomers by negative-ion electrospray mass spectrometry

Tetra- and trifluoronitroanilines were studied by electrospray ionization mass spectrometry. These compounds gave signals only in the negative-ion mode. It was found that the so-called 'in-source' fragmentation, induced by cone voltage increase, enables differentiation of isomers. For para-nitroanilines, in contrast to ortho derivatives, the loss of NO(2) was the most favored process and other fragment ions were characterized by low abundances. For trifluoro conjugates the substitution pattern of aromatic ring by fluorine atoms also affected their fragmentation patterns. For example, in 2,3,6-trifluoro-4-nitroaniline, in contrast to 2,3,5-trifluoro-4-nitroaniline, efficient NO loss, followed by HF loss, took place.     

Multireference ab initio calculations on reaction intermediates of the multicopper oxidases

The multicopper oxidases (MCOs) couple the four-electron reduction of dioxygen to water with four one-electron oxidations of various substrates. Extensive spectroscopic studies have identified several intermediates in the MCO catalytic cycle, but they have not been able to settle the structures of three of the intermediates, viz. the native intermediate (NI), the peroxy intermediate (PI), and the peroxy adduct (PA). The suggested structures have been further refined and characterized by quantum mechanical/molecular mechanical (QM/MM) calculations. In this paper, we try to establish a direct link between theory and experiment, by calculating spectroscopic parameters for these intermediates using multireference wave functions from the multistate CASPT2 and MRDDCI2 methods. Thereby, we have been able to reproduce low-spin ground states (S = 0 or S = 1/2) for all the MCO intermediates, as well as a low-lying (approximately 150 cm-1) doublet state and a doublet-quartet energy gap of approximately 780 cm-1 for the NI. Moreover, we reproduce the zero-field splitting (approximately 70 cm-1) of the ground 2E state in a D3 symmetric hydroxy-bridged trinuclear Cu(II) model of the NI and obtain a quantitatively correct quartet-doublet splitting (164 cm-1) for a mu3-oxo-bridged trinuclear Cu(II) cluster. All results support the suggestion that the NI has an O2- atom in the center of the trinuclear cluster, whereas both the PI and PA have an O22- ion in the center of the cluster, in agreement with the QM/MM results and spectroscopic measurements.     

Towards the map of quantum gravity

In this paper we point out some possible links between different approaches to quantum gravity and theories of the Planck scale physics. In particular, connections between loop quantum gravity, causal dynamical triangulations, Ho?ava–Lifshitz gravity, asymptotic safety scenario, Quantum Graphity, deformations of relativistic symmetries and nonlinear phase space models are discussed. The main focus is on quantum deformations of the Hypersurface Deformations Algebra and Poincaré algebra, nonlinear structure of phase space, the running dimension of spacetime and nontrivial phase diagram of quantum gravity. We present an attempt to arrange the observed relations in the form of a graph, highlighting different aspects of quantum gravity. The analysis is performed in the spirit of a mind map, which represents the architectural approach to the studied theory, being a natural way to describe the properties of a complex system. We hope that the constructed graphs (maps) will turn out to be helpful in uncovering the global picture of quantum gravity as a particular complex system and serve as a useful guide for the researchers.     

Fluorescence Properties of Selected Benzo[c]phenanthridines

The fluorescence properties of selected benzo[c]phenanthridines (BPs) were examined. The effect of structure, pH and solvent on the fluorescence properties has been investigated. It was found out that the presence of charged iminium nitrogen significantly decreased the fluorescence of the compounds. The fluorescence (intensity as well as emission spectra shape) of the investigated compounds was significantly dependent on pH as well as used solvent. The utilization in epigenetic modification mechanisms studies as demethylase probe and as possible pH indicator was suggested.     

A new stereocontrolled synthetic route to (-)-echinosporin from D-glucose via Padwa allenylsulfone [3 + 2]-anionic cycloadditive elimination

A new formal total synthesis of (-)-echinosporin has been developed based upon the Padwa [3 + 2]-cycloadditive elimination reaction of allenylsulfone 4 with the D-glucose-derived enone 14 which provides cycloadduct 12.     

Diastereoselective additions of allylmetal reagents to free and protected syn-α,β-dihydroxyketones enable efficient synthetic routes to methyl trioxacarcinoside A

Two routes to the 2,6-dideoxysugar methyl trioxacarcinoside A are described. Each was enabled by an apparent α-chelation-controlled addition of an allylmetal reagent to a ketone substrate containing a free α-hydroxyl group and a β-hydroxyl substituent, either free or protected as the corresponding di-tert-butylmethyl silyl ether. Both routes provide practical access to gram quantities of trioxacarcinose A in a form suitable for glycosidic coupling reactions.     

HERFD XAS/ATR-FTIR batch reactor cell

An autoclave reactor was modified to perform simultaneously high energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD XAS) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy measurements without altering the reactor design. This operando cell allows one to follow changes in the electronic and geometric structure of the catalyst with HERFD XAS and relate them to the simultaneously detected activity and reaction species with ATR-FTIR formed during the reaction in the liquid phase. The capability of the cell is demonstrated by two studies. The first shows the reduction of Au/CeO(2) precursors in different solvents. The second shows that mainly Au(0) is present in the hydrogenation of nitrobenzene over Au/CeO(2).