5-azido-2-aminopyridine, A New Nitrene/nitrenium Ion Photoaffinity Labeling Agent That Exhibits Reversible Intersystem Crossing Between Singlet And Triplet Nitrenes

The photochemistry of a new photoaffinity labeling (PAL) agent, 5-azido-2-(N,N-diethylamino)pyridine, was studied in aprotic and protic solvents using femtosecond-to-microsecond transient absorption and product analysis, in conjunction with ab initio multiconfigurational and multireference quantum chemical calculations. The excited singlet SI state is spectroscopically dark, whereas photoexcitation to higher-lying singlet excited S-2 and S-3 states drives the photochemical reaction toward a barrierless ultrafast relaxation path via two conical intersections to S-1, where N-2 elimination leads to the formation of the closed-shell singlet nitrene. The singlet nitrene undergoes intersystem crossing (ISC) to the triplet nitrene in aprotic and protic solvents as well as protonation to form the nitrenium ion. The ISC rate constants in aprotic solvents increase with solvent polarity, displaying a direct gap effect, whereas an inverse gap effect is observed in protic solvents. Transient absorption actinometry experiments suggest that a solvent-dependent fraction from 20% to 50% of nitrenium ions is generated on a time scale of a few tens of picoseconds. The closed-shell singlet and triplet nitrene are separated by a small energy gap in protic solvents. As a result, the unreactive triplet state nitrene undergoes delayed, thermally activated reverse ISC to reform the reactive closed-shell singlet nitrene, which subsequently protonates, forming the remaining fraction of nitrenium ions. The product studies demonstrate that the resulting nitrenium ion stabilized by the electron-donating 4-amino group yields the final cross-linked product with high, almost quantitative efficiency. The enhanced PAL function of this new azide with respect to the widely applied 4-amino-3-nitrophenyl azide is discussed

Effect of plastic coating on the density of plasma formed in Si foil targets irradiated by ultra-high-contrast relativistic laser pulses

The formation of high energy density matter occurs in inertial confinement fusion, astrophysical, and geophysical systems. In this context, it is important to couple as much energy as possible into a target while maintaining high density. A recent experimental campaign, using buried layer (or "sandwich" type) targets and the ultrahigh laser contrast Vulcan petawatt laser facility, resulted in 500 Mbar pressures in solid density plasmas (which corresponds to about 4.6×107J/cm3 energy density). The densities and temperatures of the generated plasma were measured based on the analysis of X-ray spectral line profiles and relative intensities

COMBINED FEMORAL FIXATION TECNIQUE IN HAMSTRING TENDON ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION: ASESSMENT OF TUNNEL WIDENING

Purpose – to assess the influence of combined femoral fixation technique during arthroscopic ACL reconstruction on the femoral tunnel widening at long term follow-up.Material and methods. 99 patients with primary hamstring tendon (HT) ACL reconstruction performed in 2007-2008 were analyzed. In the study group (42 patients) on the femoral side a combined cortical suspension (Endobutton CL, Smith & Nephew) and transverse (Rigid Fix, Depuy Mitek) fixation of graft was used. In control group, isolated cortical suspension fixation (Endobutton CL, Smith & Nephew) was used. On the tibial side for graft fixation a biodegradable screw (Biointrafix, DePuy Mitek) was used in all cases. Tunnel widening was calculated in percentage against primary tunnel diameter created during the surgery. MRI data were exported to eFilm (Merge Healthcare software), measurement of femoral tunnel diameters was performed on T1 sequences in coronal and sagittal planes on three different levels.Results. The mean age at the last follow up in the study group was 38.9±1.4, in control group – 38,6±1,08. The median time from surgery to follow up was 9 years and 4 months in the study group and 8 years 7 months in the controls. The incidence of graft failure in the study group was reported as 14.3%, while in the control group as 17,5%. The median femoral tunnel widening was larger in the control group at the joint aperture and midsection levels both in coronal and sagittal plane, although there was no statistically significant differences (p>0,05).Conclusion. The combination of cortical suspension and transverse HT femoral graft fixation technique is likely to reduce tunnel enlargement at the long term follow-up. However further research and larger sample groups are required

МИГРАЦИОННЫЕ ПРОЦЕССЫ «ВОСТОК-ЗАПАД» В КОНТЕКСТЕ ЕВРОПЕЙСКОЙ СИСТЕМЫ ЭКОНОМИЧЕСКОЙ БЕЗОПАСНОСТИ

The article refl ects the infl uence of the migration processes to the economic security of European Union. The article underlines most common economical risks in case if there is an increase of the volume of migration and describes the ways how to reduce those risks.The main conclusions obtained from the results of the study, can be structured as follows: trends and consequences of the migration crisis in the European Union are defi ned by the set of reasons that are due on the one hand the policy of transparency being implemented by individual countries, making the whole European Union is the center of attraction of immigrants (primarily from the MENA countries) and other hand, the intense and growing fl ow of migrants creates regional threats, including the European Union's economic security; the problem of ensuring the economic security of the European Union in the context of the impact of the migration crisis is most actual issue at the moment and the main reason is that the accumulation of the fl ow of migrants to the strongest European economy – Germany. In this case, not only Germany, but also France (and until recently UK) had to improve the economic and social consequences of migration and also to implement measures aimed to recover from fi nancial crisis of the last few years, the consequences of which to date are shown in the many social and economic areas of the European Union; addressing the problem with migration crisis in the European Union seems to use a special system of measures, in which on the one hand realized containment of migration fl ows and on the other hand held solutions aimed at the assimilation of migrants in multicultural environment with full adoption of the latest socio-economic, democratic and moral values specifi c to European societies.В статье анализируется влияние миграционных процессов на систему экономической безопасности Европейского союза. Определяются основные риски для европейской экономики связанные с увеличением миграционного потока и углублением кризиса, выделены механизмы снижения этих рисков, а также решения проблем миграции. Основные выводы, полученные по результатам проведенного исследования, можно структурировать следующим образом:• тенденции и последствия миграционного кризиса в Европейском Союзе определяются совокупностью причин, которые обусловлены, с одной стороны, политикой открытости, реализуемой отдельными странами, что делает весь Европейский Союз центром притяжения мигрантов (в первую очередь из стран MENA). Но, с другой стороны, интенсивный и нарастающий поток мигрантов создает угрозы региональной, и в том числе экономической безопасности Европейского Союза;• проблема обеспечения экономической безопасности Европейского Союза в контексте влияния миграционного кризиса стоит наиболее остро. И основная тому причина: аккумуляция потока мигрантов в наиболее сильной европейской экономике – Германии. При этом, не только Германия, но и Франция (а до недавнего времени и Великобритания) вынуждены не только устранять экономические и социальные последствия миграции, но и реализовывать меры, направленные на нивелирование финансового кризиса прошлых лет, последствия которого до настоящего момента проявляются во многих социальных и экономических сферах Европейского Союза;• решение проблемы миграционного кризиса в Европейском Союзе видится в использовании специальной системы мер, в рамках которой, с одной стороны, реализуются меры сдерживания миграционного потока, а с другой стороны, проводятся решения, направленные на ассимиляцию мигрантов в мультикультурную среду с полным принятием последними социально-экономических, демократических и моральных ценностей, характерных для европейского общества

Proton deflectometry of a capacitor coil target along two axes

A developing application of laser-driven currents is the generation of magnetic fields of picosecond-nanosecond duration with magnitudes exceeding. Single-loop and helical coil targets can direct laser-driven discharge currents along wires to generate spatially uniform, quasi-static magnetic fields on the millimetre scale. Here, we present proton deflectometry across two axes of a single-loop coil ranging from 1 to 2 mm in diameter. Comparison with proton tracking simulations shows that measured magnetic fields are the result of kiloampere currents in the coil and electric charges distributed around the coil target. Using this dual-axis platform for proton deflectometry, robust measurements can be made of the evolution of magnetic fields in a capacitor coil target