Mass spectrometry of π-complexes of transition metals 38—keto-enol tautomerization of molecular ions of acetyl- and propionyl-ferrocenes in the gas phase

Fragmentation of the acetyl- and propionyl-ferrocenes under electron impact together with the rupture of C? CO bonds, characteristic of ketones, also includes elimination of water and migration of the OH group to the central metal atom, which is due to keto-enol tautomerization of the acyl group in molecular or fragment ions.     

An approach for an algorithmic solution of discrete optimal control problems and their game-theoretical extension

We consider time discrete systems which are described by a system of difference equations. The related discrete optimal control problems are introduced. Additionally, a gametheoretic extension is derived, which leads to general multicriteria decision problems. The characterization of their optimal behavior is studied. Given starting and final states define the decision process; applying dynamic programming techniques suitable optimal solutions can be gained. We generalize that approach to a special gametheoretic decision procedure on networks. We characterize Nash equilibria and present sufficient conditions for their existence. A constructive algorithm is derived. The sufficient conditions are exploited to get the algorithmic solution. Its complexity analysis is presented and at the end we conclude with an extension to the complementary case of Pareto optima.Dmitrii Lozovanu was Supported by BGP CRDF-MRDA MOM2-3049-CS-03.     

Subharmonic bifurcation from infinity

We are concerned with a subharmonic bifurcation from infinity for scalar higher order ordinary differential equations. The equations contain principal linear parts depending on a scalar parameter, 2π-periodic forcing terms, and continuous nonlinearities with saturation. We suggest sufficient conditions for the existence of subharmonics (i.e., periodic solutions of multiple periods 2πn) with arbitrarily large amplitudes and periods. We prove that this type of the subharmonic bifurcation occurs whenever a pair of simple roots of the characteristic polynomial crosses the imaginary axis at the points ±αi with an irrational α. Under some further assumptions, we estimate asymptotically the parameter intervals, where large subharmonics of periods 2πn exist. These assumptions relate the quality of the Diophantine approximations of α, the rate of convergence of the nonlinearity to its limits at infinity, and the smoothness of the forcing term.     

A structural study of (1RS,2SR,3RS,4SR,5RS)‐2,4‐dibenzoyl‐1,3,5‐triphenylcyclohexan‐1‐ol chloroform hemisolvate and (1RS,2SR,3RS,4SR,5RS)‐2,4‐dibenzoyl‐1‐phenyl‐3,5‐bis(2‐methoxyphenyl)cyclohexan‐1‐ol

(1RS,2SR,3RS,4SR,5RS)‐2,4‐Dibenzoyl‐1,3,5‐triphenylcyclohexan‐1‐ol or (4‐hydroxy‐2,4,6‐triphenylcyclohexane‐1,3‐diyl)bis(phenylmethanone), C₃₈H₃₂O₃, (1), is formed as a by‐product in the NaOH‐catalyzed synthesis of 1,3,5‐triphenylpentane‐1,5‐dione from acetophenone and benzaldehyde. Single crystals of the chloroform hemisolvate, C₃₈H₃₂O₃·0.5CHCl₃, were grown from chloroform. The structure has triclinic (P) symmetry. One diastereomer [as a pair of (1RS,2SR,3RS,4SR,5RS)‐enantiomers] of (1) has been found in the crystal structure and confirmed by NMR studies. The dichoromethane hemisolvate has been reported previously [Zhang et al. (2007). Acta Cryst. E 63 , o4652]. (1RS,2SR,3RS,4SR,5RS)‐2,4‐Dibenzoyl‐3,5‐bis(2‐methoxyphenyl)‐1‐phenylcyclohexan‐1‐ol or [4‐hydroxy‐2,6‐bis(2‐methoxyphenyl)‐4‐phenylcyclohexane‐1,3‐diyl]bis(phenylmethanone), C₄₀H₃₆O₅, (2), is also formed as a by‐product, under the same conditions, from acetophenone and 2‐methoxybenzaldehyde. Crystals of (2) have been grown from chloroform. The structure has orthorhombic (Pca2₁) symmetry. A diastereomer of (2) possesses the same configuration as (1). In both structures, the cyclohexane ring adopts a chair conformation with all bulky groups (benzoyl, phenyl and 2‐methoxyphenyl) in equatorial positions. The molecules of (1) and (2) both display one intramolecular O—H...O hydrogen bond.     

Modeling and evaluation of cyber-physical systems in civil engineering

A cyber-physical system (CPS) is a coupled system integrating computing, networking, and physical processes. Through actuation, cyber-physical systems control the physical processes, usually with feedback loops, where the physical processes affect computing and networking processes, and vice versa. In civil engineering, the most common fields of CPS applications are structural health monitoring (SHM) and structural control. A typical CPS task is the assessment of a structure based on (i) collected measurement data and (ii) a corresponding model. However, for an accurate and precise assessment of a structure, the CPS itself must be modeled and evaluated. In this paper, a conceptual modeling and evaluation approach is proposed, in which each part of a CPS is evaluated individually. In this study, the conceptual approach is presented for modeling and evaluation of CPS in civil engineering. The evaluation is based on an abstract approach allowing a discussion of a principle (i.e. general) model structure of a CPS, identifying critical issues to be studied in more detail in future research. (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Formation of the paramagletic Ni(I) π-allyl complex in the Ni(allyl)2 - (2,6-diisopropylphenyl)diazabutadiene system

It has been shown that the reaction of Ni(allyl)₂ with (2,6-diisopropylphenyl)diazabutadiene gives the imino-amide Ni complex (1). The imino-amide moiety of this complex undergoes some complicated rearrangements resulting in spontaneous formation of a paramagnetic π-allyl Ni(I) complex. Nickel complexes formed in the system have been studied with ESR, FTIR, 2D NMR, and mass spectrometry. The structure of complex 1 was studied with X-ray diffraction.     

Combining electrophoresis with detection under ultraviolet light and multiple ultrafiltration for isolation of humic fluorescence fractions

Polyacrylamide gel electrophoresis of chernozem soil humic acids (HAs) followed by observation under UV (312 nm) excitation light reveals new low molecular weight (MW) fluorescent fractions. Ultrafiltration of HAs sample in 7 M urea on a membrane of low nominal MW retention (NMWR, 5 kDa) was repetitively used for separation of fluorescent and non-fluorescent species. Thirty ultrafiltrates and the final retentate R were obtained. Fluorescence maxima of separate ultrafiltrates were different and non-monotonously changed in the range of 475–505 nm. Fluorescence maxima of less than 490 nm were detected only in the four first utrafiltrates. For further physical–chemical analyses all utrafiltrates were combined into a fraction called UF < 5 (NMW < 5 kDa). Retentate R demonstrated very weak fluorescence under 270 nm excitation, while fluorescence intensity of UF < 5 was about six times higher than of the bulk HAs. Fraction UF < 5 was further ultrafiltrated on membranes of MNWR 3 kDa and 1 kDa, yielding three subfractions UF3-5, UF1-3 and UF < 1 with NMW 3–5 kDa, 1–3 kDa and <1 kDa, respectively. The validation of the UF procedure was performed by size exclusion chromatography on Sephadex G-25 column. The fluorescence maxima were found to be at 505, 488 and 465 nm for UF3-5, UF1-3 and UF < 1, respectively, with increasing of fluorescence intensity from UF3-5 to UF1-3 to UF < 1 fraction. EPR analysis showed that the amount of free radicals was the largest in retentate R and drastically decreased in fluorescent ultrafiltrates. The results demonstrate that more than one fluorophore is present in chernozem soil HAs complex.