EPR Evidence of Unusual Dopant Valency States in Nanocrystalline Er-doped CeO<inf>2</inf>

© 2015, Springer-Verlag Wien. The structure and oxidation state of the Er dopant cation in CeO2 single crystal and nanocrystals with size ranging from 22 to 300 nm are studied using electron paramagnetic resonance (EPR) spectroscopy at X- and at Q-band near liquid-He temperatures. Besides the expected EPR line due to Er3+ in cubic sites in the lattice, unusual EPR lines with g values around 14 and 20 are observed in nanocrystalline CeO2. The appearance of these lines suggests the formation of non-Kramers Er2+, Er4+ ions, which becomes increasing favorable with decreasing nanoparticle size. Formation of rare earth ions with such unusual oxidation states in nanoparticles can be exploited in tuning their catalytic activity and optical properties

Structure of pravastatin and its complex with sodium dodecyl sulfate micelles studied by NMR spectroscopy

© 2014 John Wiley & Sons, Ltd. The aim of this work was to study the mechanisms of interaction between pravastatin and cell membranes using model membranes (sodium dodecyl sulfate micelles) by nuclear magnetic resonance spectroscopy methods. On the basis of the nuclear magnetic resonance experiments, it was established that pravastatin can form intermolecular complexes with sodium dodecyl sulfate micelles by the interaction of its hydrophilic groups with the polar surface of the micelle. Conformational features of pravastatin molecule were also studied

Technique of the analysis and assessment of innovative industrial risks at different stages of innovative activity

© 2016, Econjournals. All rights reserved.High rates of innovation in enterprises require setting a number of scientific and technical problems related to the evaluation and analysis of innovative industrial risks and their control systems. The article proposes an original technique for evaluation of innovative industrial risks at different stages of innovation. Its feature is that the rate determined by the survivability of the economic system. The basis of the study developed the method for determining the survivability is the definition of the integral index of vitality based on a comprehensive assessment of the production system. The closer the result of this indicator to one, the better the control system will determine the problem areas in the implementation of innovation and more efficient use of a set of measures to address the problems identified. Methods of assessing and analyzing the vitality of enterprises is available for the purposes of risk management as a tool of analysis to identify reasons for the decline performance of innovation. In this regard, we determined preliminary values of specific factors and the limit values for these indicators

Liquid Biopsy as a Method for Minimally Invasive Diagnosis of Thyroid Cancer

Thyroid cancer is the 9th most common cancer in the world. The five-year survival rate for this disease is over 98%. However, in some patients there are cases of rapidly progressive treatment-resistant cancer that cannot be differed from poor-invasive cancer by routine methods. Liquid biopsy could be one of the methods to solve this problem. This procedure consists in the analysis of tumor derivatives (in particular, circulating DNA) in body fluids. The analysis of hotspot mutations and patterns of epigenetic regulation, which are usual for neoplasms with a certain genotype, is used to identify the tumor component in the total mass of circulating DNA. The increase of circulating tumor DNA in the plasma is observed several months ahead of the characteristic signs at MR images of patients, and also surpasses conventional biomarkers such as calcitonin in medullary thyroid carcinoma. In addition, a possibility of minimally invasive determination of the tumor genotype by analyzing circulating DNA is important to select the optimal chemotherapy. This review discusses the current advances in the analysis of circulating tumor DNA in thyroid cancers such as papillary, follicular, medullary, and anaplastic carcinomas

Dynamic NMR study of dinitrophenyl derivatives of seven-membered cyclic ketals of pyridoxine

© 2015 John Wiley & Sons, Ltd. Two pyridoxine derivatives containing a dinitrophenyl moiety were investigated by 1H NMR spectroscopy. Conformational dynamics in solution were studied for each compound using dynamic NMR experiments. It was shown that both compounds studied are involved into two conformational exchange processes. The first process is a transformation of the seven-membered cycle conformation between the enantiomeric P-twist and M-twist forms, and the second is a rotation of the dinitrophenyl fragment of the molecules around the C-O bond. Energy barriers of both conformational transitions were determined

Spatial Structure and Conformational Mobility of Seven-Membered Cyclic Acetals and Ketals Containing Pyridoxine Moiety in Solution by NMR Methods

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. In the last decade, pyridoxine derivatives were widely used for the synthesis of molecules with important biological and physical properties. However, rational synthesis of the compounds with desirable biochemical or physical properties often requires information about their spatial structure and conformational mobility. NMR spectroscopy is a powerful tool for conformational analysis of biologically important samples, such as pyridoxine derivatives, in solution. This paper is devoted to a review of the results obtained by our group over the last 5 years on the NMR study of nine newly synthesized pyridoxine derivatives in acetone solution. It was shown that studied compounds are involved into several conformational exchange processes. The activation energies of all observed conformational exchange processes were calculated

Crystal structure and dynamic behavior of [Ni{PhNHC(S)NP(S)(OPr i)2-S,S}2] complex in dichloromethane solution

The crystal structure of the complex [Ni{PhNHC(S)NP(S)(OPr i)2-S,S}2] has been determined and its behavior in dichloromethane solution investigated by NMR 31P spectroscopy. The X-ray structural analysis shows the nickel atom at the symmetry center in a distorted square-planar arrangement with trans-disposition of the ligands. The six-membered cycle NiS(1)PNCS(2) has the form of the asymmetric boat. In dichloromethane solutions of the compound four signals have been detected by 31P-{1H} NMR method. These signals are related to three diamagnetic square-planar isomers with different dispositions and conformations of two ligands in anti-orientation: trans-chair-boat (A), cis-boat-boat (B), and trans-boat-boat (C). These isomers are in slow exchange equilibria. It was shown that all these forms are in rather fast chemical exchange with minor (unobserved) paramagnetic pseudo-tetrahedral isomers (AT, B T, and CT). The thermodynamic constants of equilibria between A, B, and C as well as rate constants and activation parameters for conversion of three square-planar to respective pseudo-tetrahedral forms were calculated from the 31P-{1H} NMR data. © 2005 Elsevier Ltd. All rights reserved

¹H NMR Characterization of Two New Pyridoxine Derivatives

© 2016, Springer Science+Business Media New York.Two new pyridoxine derivatives were studied by dynamic 1H NMR spectroscopy. The complete 1H NMR data for two pyridoxine derivatives are presented. Assignment of the signals in the spectra was achieved using 1D and 2D COSY NMR experiments