Orbit and intrinsic spin-up of the newly discovered transient X-ray pulsar Swift J0243.6+6124

We present the orbital solution for the newly discovered transient Be X-ray binary Swift J0243.6+6124 based on the data from gamma-ray burst monitor onboard Fermi obtained during the Oct 2017 outburst. We model the Doppler induced and intrinsic spin variations of the neutron star assuming that the later is driven by accretion torque and discuss the implications of the observed spin variations for the parameters of the neutron star and the binary. In particular we conclude that the neutron star must be strongly magnetized, and estimate the distance to the source at $\sim$5 kpc.Comment: accepted in A&

Orbital parameters of V 0332+53 from 2015 giant outburst data

We present the updated orbital solution for the transient Be X-ray binary V 0332+53 comple- menting historical measurements with the data from the gamma-ray burst monitor onboard Fermi obtained during the outburst in June-October 2015. We model the observed changes in the spin- frequency of the pulsar and deduce the orbital parameters of the system. We significantly improve existing constrains and show that contrary to the previous findings no change in orbital parameters is required to explain the spin evolution of the source during the outbursts in 1983, 2005 and 2015. The reconstructed intrinsic spin-up of the neutron star during the latest outburst is found to be comparable with previosly observed values and predictions of the accretion torque theory.Comment: 3 pages, 2 figures, submitted to A&

X-ray pulsars through the eyes of INTEGRAL

Recent results of the spectral and timing analysis of X-ray pulsars in hard X-rays with the INTEGRAL observatory are reviewed. The evolution of the cyclotron line energy with the source luminosity was studied in detail for the first time for several sources. It was shown that for V0332+53 this dependence is linear, but for 4U0115+63 and A0535+262 it is more complicated. There are some evidences of the "reverse" evolution for GX301-2 and Her X-1, and no evolution was found for Vela X-1, Cen X-3, etc. A strong dependence of the pulse fraction on the energy and source luminosity was revealed and studied in detail. A prominent feature in the pulse fraction dependence on the energy was discovered near the cyclotron frequency for several bright sources. The obtained results are compared with results of observations in standard X-rays and briefly discussed in terms of current models; some preliminary explanations are proposed.Comment: 12 pages, 8 figure

Fluoride-activated Catalysis

The design of new catalytic systems is generally based on the modification of the catalyst structure. Often this leads to more and more complicated structures which require multi-step synthesis and restricts widespread use among different research groups. It would be beneficial for academic research and industry to develop methods for the activation of catalysts by using some simple and commercially available additives. In this thesis fluoride additives, such as [Bu4N]Ph3SiF2] or CsF were studied as such activating additives for different organometallic complexes. The use of the fluoride additives results in the in situ formation of active metal fluoride complexes. We successfully applied this tactic to five different reactions, namely, the aluminum-catalyzed cycloaddition of CO2 to epoxides, vanadium-catalyzed asymmetric trimethylsilylcyanation of aldehydes, nickel-catalyzed asymmetric Michael addition of dimethyl malonate to nitroalkenes, rhodium- and cobalt-catalyzed reductive opening of tetrahydrofuran with amines, and ruthenium-catalyzed reductive alkylation of ketones by aldehydes. Depending on the type of transformation the use of the fluoride additive resulted in an increase in activity, selectivity, milder reaction conditions or even achieving new reactivity. For example, in the case of the vanadium-catalyzed asymmetric trimethylsilylcyanation of aldehydes use of [Bu4N]Ph3SiF2] resulted in a twentyfold increase in catalytic activity with turnover numbers of the catalyst reaching 20000. This resulted in one of the most active catalytic systems for this type of transformation and it is based on a commercially available chiral salen ligand and an inexpensive vanadium source