Search

The European XFEL is a hard X-ray free-electron laser (FEL) based on a high-electron-energy superconducting linear accelerator. The superconducting technology allows for the acceleration of many electron bunches within one radio-frequency pulse of the accelerating voltage and, in turn, for the generation of a large number of hard X-ray pulses. We report on the performance of the European XFEL accelerator with up to 5,000 electron bunches per second and demonstrating a full energy of 17.5 GeV. Feedback mechanisms enable stabilization of the electron beam delivery at the FEL undulator in space and time. The measured FEL gain curve at 9.3 keV is in good agreement with predictions for saturated FEL radiation. Hard X-ray lasing was achieved between 7 keV and 14 keV with pulse energies of up to 2.0 mJ. Using the high repetition rate, an FEL beam with 6 W average power was created.

Nanodiamond from ozone purification (NDO) demonstrates very distinctive properties within the class of detonation nanodiamonds, namely very high acidity and high colloidal stability in a broad pH range. To understand the origin of these unusual properties of NDO, the nature of the surface functional groups formed during detonation soot oxidation by ozone needs to be revealed. In this work, thermal desorption mass spectrometry (TDMS) and IR spectroscopy were used for the identification of surface groups and it was concluded that carboxylic anhydride groups prevail on the NDO surface. On the basis of the temperature profiles of the desorbed volatile products and their mass balance, it is hypothesized that decomposition of carboxylic anhydride groups from NDO during heating proceeds by two different mechanisms. Other distinctive features of NDO in comparison with air-treated nanodiamond are also reported.

We investigated the photon-emission spectrum of Xe atoms upon photoionization of the Xe 3d-subshell. The 5p-4d spectrum is emitted in the process of the cascading decay of the 3d-vacancy and has a complex multi-component structure reflecting a great number of transitions from various ionic configurations produced during the cascade development. The spectrum is assigned by the direct construction of the cascade de-excitation tree. 21 different transitions between configurations of multiply charged Xe ions (+2 to +6) are found to be contributing to the spectrum. The 5p-4d partial fluorescence yield is found to be six times greater for the 3d-ionization than for the 4d-ionization. The effect of the multiplet splitting in the initial and final states of the emitting transitions is studied.

We use density-functional ab initio molecular dynamics to investigate the kinetics of N/VN(001) surface reactions at temperatures ranging from 1600 to 2300 K. N adatoms (Nad) on VN(001) favor epitaxial atop-V positions and diffuse among them by transiting through 4-fold hollow (FFH) sites, at which they are surrounded by two V and two N surface atoms. After several atop-V → FFH → atop-V jumps, isolated N adatoms bond strongly with an underlying N surface (Nsurf) atom. Frequent Nad/Nsurfpair exchange reactions lead to N2desorption, which results in the formation of an anion surface vacancy. N vacancies rapidly migrate via in-plane ⟨110⟩ jumps and act as efficient catalysts for the dissociative chemisorption of incident N2molecules. During exposure of VN(001) to incident atomic N gas atoms, Nad/Nadrecombination and desorption is never observed, despite a continuously high N monomer surface coverage. Instead, N2desorption is always initiated by a N adatom removing a N surface atom or by energetic N gas atoms colliding with Nador Nsurfatoms. Similarities and differences between N/VN(001) vs. previous N/TiN(001) results, discussed on the basis of temperature-dependent ab initio electronic structures and chemical bonding, provide insights for controlling the reactivity of NaCl-structure transition-metal nitride (001) surfaces via electron-concentration tuning.

The near edge KN23-fine structure of Kr atom is calculated viathe configuration interaction method including a monopole rearrangement of electron shells. The theoretical spectrum form is in good agreement with the experimental one. The calculated absolute values of the oscillator strenghts and the photoabsorption cross section are predictions.

Influence of the SCN1A IVS5N + 5 G>A Polymorphism on Therapy with Carbamazepine for EpilepsyCarbamazepine (CBZ) blocks neuronal sodium channels in a voltage- and frequency-dependent manner, delaying the recovery of the channels from the inactivated state, reducing the number of action potentials within a burst, and decreasing burst duration. The α-subunit of the first neuronal sodium channel (SCN1A) is a major gene in different epilepsies. A synonymous polymorphism (SCN1A IVS5N + 5 G>A or rs3812718) is common in exon 5 of this gene. Mutations in the α-unit of this gene are associated with CBZ-resistant epilepsy and a higher maintenance dose of CBZ. We have investigated the association of this single nucleotide polymorphism (SNP) and epilepsy, efficacy and dose-dependence of CBZ therapy in 147 adult Macedonian patients and 137 non epileptic controls. No significant differences in allelic frequencies and genotype distribution were found between patients and controls (p= 0.94278), or between CBZ-responsive and unresponsive patients (p= 0.55449). An association between the A allele and a higher maintenance dose in CBZ-responsive patients was detected. No statistical difference was found between the plasma levels of CBZ and genotype of patients receiving the same dose, indicating that the variant exerts its effect at the level of receptor responsiveness. The predictive value of pretreatment testing showed a minor insignificant difference between patients with different genotypes, primarily due to a small number of patients.

There is strong clinical evidence that controlling cerebral venous oxygenation (oxyhemoglobin saturation) is critically important for patients with severe traumatic brain injury as well as for patients undergoing cardiac surgery. However, the only available method for cerebral venous blood oxygenation monitoring is invasive and requires catheterization of the internal jugular vein. We designed and built a novel optoacoustic monitor of cerebral venous oxygenation as measured in the superior sagittal sinus (SSS), the large midline cerebral vein. To the best of our knowledge, optical monitoring of cerebral venous blood oxygenation through overlying extracerebral blood is reported for the first time in this paper. The system was capable of detecting SSS signals in vivo at 700, 800, and 1064 nm through the thick (5–6 mm) sheep skull containing the circulating blood. The high (submillimeter) in-depth resolution of the system provided identification of the SSS peaks in the optoacoustic signals. The SSS peak amplitude closely followed the actual SSS blood oxygenation measured invasively using catheterization, blood sampling, and “gold standard” CO-Oximetry. Our data indicate the system may provide accurate measurement of the SSS blood oxygenation in patients with extracerebral blood over the SSS.

Nanoscale multilayer TiAlCN/VCN coatings with bilayer thickness ?=2·2 nm were deposited by the combined high power impulse magnetron sputtering (HIPIMS)/unbalanced magnetron sputtering technology. The V+HIPIMS etching produced atomically clean interface and V implantation resulting in enhanced coating adhesion LC=58 N. High resolution transmission electron microscopy and electron energy loss spectroscopy revealed that in TiAlCN/VCN, carbon forms a lateral phase between the nanolayers, producing low shear strength interfaces. This results in a well defined nanometre scale layer by layer wear mechanism, which is the key for prevention of tribofilm and consequently thick built up layer formation. In dry milling of Al 7010-T 7651 alloy, TiAlCN/VCN outperformed state of the art diamond like carbon, Cr/WC/a-CH coated and uncoated end mills by factors of 4 and 8 respectively. In turning of Ti alloys (Ti0·90Al0·06V0·04) the TiAlCN/VCN coated cemented carbide inserts produced two to three times more components (orthopaedic implants), as compared to uncoated tools.

We investigated the photon-emission spectrum of Xe atoms upon photoionization of the Xe 3d-subshell. The 5p-4d spectrum is emitted in the process of the cascading decay of the 3d-vacancy and has a complex multi-component structure reflecting a great number of transitions from various ionic configurations produced during the cascade development. The spectrum is assigned by the direct construction of the cascade de-excitation tree. 21 different transitions between configurations of multiply charged Xe ions (+2 to +6) are found to be contributing to the spectrum. The 5p-4d partial fluorescence yield is found to be six times greater for the 3d-ionization than for the 4d-ionization. The effect of the multiplet splitting in the initial and final states of the emitting transitions is studied.

ABSTRACTThe population status of bleak (Alburnus alburnut (L.) in sand-pit lake Chepintsi near Sofia by using some biological factors as growth rate, condition and fecundity was investigated. The maximum age, length and body mass of bleak were 3 years, 12.7 mm and 20 g, respectively. The first, second and third age group were 5.77%, 63.46%, 30.77% respectively. The linear and body mass growth rate were described by the equations: SL=1.3487+2.6601R (r=0.88); W=0.1499L1.8499(r=0.95), respectively. The condition coefficient of bleak (k) was the lower than that for other populations from different water bodies. Also the populations from different water basins were compared by the body mass at the same length. Fecundity was 7 168 eggs, the average was 1 707–12 284 eggs. The fecundity-length and fecundity-weight relationship were described by the equations: F=387.32L+4365.7 (r=0.46); F=1368.4W-3151.9 (r=0.59) respectively.

Abstract: The electronic band structure of the two main crystallographic modifications of silicon nitride, namely, the α-Si3N4 and β-Si3N4 phases, is calculated from the first principles. The estimates obtained for the effective charges of silicon and nitrogen atoms and those for the effective masses of electrons and holes in the α-Si3N4 phase are in good agreement with the available experimental data for amorphous silicon nitride a-Si3N4. The calculations performed demonstrate that the effective mass tensor determined for the β-Si3N4 phase differs substantially from the effective mass tensor obtained for the α-Si3N4 phase.

Abstract: A two-dimensional mathematical model of the mechanical response of a human head to a shock action is proposed. It describes the spatial distribution of the mechanical loads on the brain. Some numerical results obtained using the grid characteristic methods on unstructured triangular grids are presented.

The 2p51/2np' J= 0, 1, 2 and 2p51/2nf' J= 2 autoionizing Rydberg states (ARS) of Ne have been studied by two-step two-colour photoionization of ground-state neon atoms via the intermediate states 2p53/23s J= 1 and 2p51/23s' J= 1, followed by time-of-flight ion detection. Strong interference between the direct and virtual intershell photoexcitation channels in ARS production, especially for the np' J= 0 series, is revealed. The computed reduced width ?r= 6431cm?1and the quantum defect ?p= 0.7634 of the 2p51/213p' J= 0 resonance agree well with the experimental results ? = 5334cm?1and ?p= 0.7662 determined with a Fano-type lineshape analysis. The measured lineshapes of the np' J= 0, 1, 2 resonances are also in good agreement with the many-electron computation.

The photoabsorption of Ar is studied experimentally and theoretically for energies between 32.5 eV and 33.0 eV. Resonant excitation and autoionization of doubly excited 3p4(3P)4s2P3/2,1/2np Rydberg states are observed as dominant mechanism to populate doublet and quartet satellites of the 3p44s, 3d configurations. The perturbation of the Rydberg series by promoter states is reproduced by the calculations. Measured and calculated cross sections for the strong decay channels are in good agreement. A mirror behaviour of the 3s vacancy creation and the satellite production and the influence of the radiative decay of high-lying Rydberg states on the shape of a satellite threshold are manifested.

The interaction between resonances through autoionization continua and the interaction between autoionization continua were investigated theoretically and experimentally for the photoionization process of the 4p- and 4s-shells and for the population of 4p4(3P)5s 4PJ, 4p4(3P)5s 2PJand 4p4(3P)4d 4DJsatellites of KrII. Cross sections for the satellite production and the angular distribution parameter of the fluorescence radiation were measured by photon-induced fluorescence spectroscopy after excitationx with linearly polarized monochromatized synchrotron radiation at exciting-photon energies between 28.45 eV and 29.95 eV with an exciting-photon energy resolution of 10 meV (FWHM). Measured cross sections are in good agreement with the computed ones. A refined assignment of resonances in the proximity of the 4s14p65p resonance was performed. It was concluded that there is a strong influence of the core rearrangement, of the interaction between resonances through the autoionization continua and of the interaction between autoionization continua, on the investigated processes on the basis of the observed good overall agreement between the computed and measured quantities.

Two-colour experiments combining synchrotron radiation and light pulses from a synchronized linear dye laser have been performed to investigate even-parity Xe* 5p5(2P1/2) np' and nf' resonances of atomic xenon. These autoionization states have been reached through a double-resonant excitation scheme including the short-lived intermediate states Xe* 5p5(2P3/2) 5d and 6d. Our theoretical results reproduce the experimental findings, especially the observed dramatic suppression of the np' resonances, by taking into account strong configuration interaction in the intermediate and the final states. Moreover, theory reveals that asymmetry parameters and oscillator strengths for the 5p5nf' and 5p5np' series are strongly dependent on the description of the intermediate states. The measured and calculated values for the reduced widths and the quantum defects of the 5p5nf' series are in good agreement.

Using experimental set-ups involving single photon excitation of metastable rare gas atoms Rg(mp5(m+ 1)s, J= 2, 0) by a pulsed frequency-doubled dye laser in conjunction with time-of-flight ion detection, we have investigated several even Rg(mp51/2np') autoionizing resonances of the heavier rare gas atoms Rg = Ne ? Xe (m= 2-5) at experimental bandwidths of 0.06 cm?1(Ne) and about 0.25 cm?1(Ar, Kr, Xe). New level energies (quantum defects) and widths for these resonances have been derived by a Fano-type lineshape analysis, thus yielding reduced resonance widths. The experimental spectra and the resonance parameters are compared with theoretical calculations which are based on the configuration interaction Pauli-Fock approach, including core polarization. For Rg = Ne, good agreement between the measured and the calculated results is observed. For the heavier rare gases, significant deviations between some of the existing experimental data and the theoretical results are found, indicating the need for further studies.

The photoabsorption spectrum of Kr-like Y3+ions in the very soft x-ray/extreme ultraviolet spectral range where single (4s-np) and double (4p4p-nn'') electron excitations dominate has been measured using a dual laser plasma photoabsorption technique. The corresponding photoionization cross section has been computed within the framework of the configuration interaction Pauli-Fock approach. The calculations confirm that the 4s-5p resonance drops below the 4p ionization threshold so that the first member of the 4s-np photoionization resonance series becomes 4s-6p. Also, whereas the first such series member in Rb+and Sr2+appears as a window resonance, in Y3+it switches to a normal, slightly asymmetric absorption peak. In addition, although the 4s-5p1/2resonances in the 4p51/2and 4p53/2continua are mirror images in Rb+and Sr2+and hence cancel each other, they exhibit quite different shapes in Y3+and hence we observe the residual signature of the 4s-6p1/2resonance as a weak partner to the main 4s-6p3/2resonance.

Dispersed Kr VUV-fluorescence excitation spectra and photoion yields were recorded in the exciting photon energy range between 28.4 eV and 28.7 eV with extremely narrow bandwidth (1.7 meV at 28.55 eV) of the monochromatized synchrotron radiation used as the exciting photon source. Two series of doubly excited KrI states were observed and identified as the 4s²4p⁴ (³P) 5s ⁴P_1/2 np and the 4s²4p⁴(³P)5s ²P_3/2 np series.

A theoretical model to calculate the photoion yields registered in coincidence with fixed-energy Auger electrons is developed. The intermediate-coupling approximation is used to calculate the term structure of the two-hole states reached by Auger transitions, and the branching ratios of their further Auger, Coster–Kronig and super Coster–Kronig decays into the three-hole states. The remaining parts of the cascading decay de-excitation trees are simulated in configuration-average approximation for branching ratios and transition energies. Our calculation allowed us to explain the recent M₄₅NN Auger-electron–photoion coincidence experiment upon M₄₅ photoionization of Xe.

Abstract: The deformation behavior of the epitaxial TiN/MgO (001) thin film/substrate system was studied through in-situ nanoindentation in a transmission electron microscope (TEM). The required sample geometry was prepared using Ga+ focused ion beam (FIB) etching. During room-temperature indentation, both the TiN film and the MgO substrate deformed through the motion of dislocations. The result was a localized hemispherical plastic zone in the TiN film directly under the indentation contact area, forming an 8 tilt boundary. These results show directly that small-scale plasticity in TiN can occur at room temperature through the motion of dislocations.

Chemical reactivity descriptors are computed by the use of three alternative approaches derived within the framework of density functional theory. These schemes consider the computation of orbital Fukui indices, where all valence orbitals are taken into account; the Fukui indices of each atom in the molecule from the atomic resolved hardness matrix; and the atom in molecule softnesses, expressed in mixed LCAO representation of second quantization as functions of Mayer atomic valences. The hardness matrix is constructed from the Kohn−Sham orbitals by the use of the fractional occupation number concept and Janak's extension of density functional theory. The site reactivity of molecules involved in radical attack reactions of some substituted olefins and isocyanide addition to dipolarophiles is rationalized in terms of the orbital and atomic resolved reactivity indices. The reactivity descriptors of thiophene, furane, and pyrrole are also reported and discussed. In addition, the nucleophilic attack on the allyl coordinated to the electronically asymmetric [Pd(phosphine)(imine)] fragment was considered.

Fragmented embryonic bone tissue stimulates bone regeneration. Bone formation starts not from implanted embryonic fragments, but in intact periosteum and endosteum containing cambial cells of the osteodifferon. In rabbits, recovery of damaged radial bone after implantation of fragmented embryonic bone tissue into bone defect was associated with a pronounced periosteal reaction and focal resorption of intact ulnar bone. Consolidation of damaged radial bone without implantation of fragmented embryonic bone tissue was incomplete in all experimental animals.

Fragmented embryonic bone tissue stimulates bone regeneration. Bone formation starts not from implanted embryonic fragments, but in intact periosteum and endosteum containing cambial cells of the osteodifferon. In rabbits, recovery of damaged radial bone after implantation of fragmented embryonic bone tissue into bone defect was associated with a pronounced periosteal reaction and focal resorption of intact ulnar bone. Consolidation of damaged radial bone without implantation of fragmented embryonic bone tissue was incomplete in all experimental animals.

In PVD processes, substrate cleaning by ion etching prior to deposition is a key step in achieving good film adhesion, which is essential for all coating applications. The substrate surface is generally cleaned by bombarding it with metal or gas ions, extracted from a cathodic arc or glow discharge plasma respectively, by negatively biasing the substrate. This alters substrate surface chemistry, topography, and microstructure and affects subsequent film growth and adhesion. The present study involved Cr ion bombardment of steel and tungsten carbide at bias voltages Ubof -600 and -1200 V as well as ion etching in an Ar glow discharge at Ub= -1200 V. Ion etching was followed by reactive unbalanced magnetron deposition of TiAlN based coatings. The microstructure and microchemistry of the interface region was investigated by XTEM and STEM–EDX analysis. After Ar ion pretreatment the presence of a low density substrate surface region was observed. This surface promotes the nucleation of randomly oriented grains leading to competitive growth with small column size and open boundaries. Interfaces generated after Cr ion bombardment at Ub= -600 V exhibit a local Cr deposition layer which leads also to competitive growth. In contrast, Cr ion bombardment at Ub= -1200 V results in the removal of around 100 nm of substrate material, providing a clean surface, and local epitaxial growth is observed. The different interface architecture is reflected by the critical loads obtained in scratch testing of 3·5 μm thick TiAlCrYN coatings deposited on tungsten carbide, ranging from 33 N for Ar bombardment to 141 N achieved by Cr ion bombardment at Ub= -1200 V. Cr ion pretreatment at Ub= -600 V results in a critical load of 68 N. The influence on the lifetime of coated tungsten carbide tools is also discussed.

Ice cover studies, affecting one of the basic elements of the Arctic environment, have played an important part of the research programs of the Soviet Union's North Pole drift-ice stations. These research programs have included investigations of the heat exchange between atmosphere and ocean, predetermining the formation of ice cover with a particular morphology and properties, as well as salinity, structure, strength and thermal and radiation properties. Techniques have been developed for transforming the surface of the ice cover.

Calculations have been performed on the integral shapes of the Kβη lines, which are long-wave satellites of the Kβ1 lines, for Cl, Ti, and Fe, where allowance has been made for interference between states in the 2p−1 and 3p−2εp configurations. The calculations show that these satellites represent short-wave branches of the Kα lines strengthened by the 3p-1s transition with simultaneous M electron ejection. The strong interference between the amplitudes of these processes in the final state means that it is in principle quite impossible to speak of the intensities of the Kβη satellites without stating how they are isolated from the measured spectrum.

One-dimensional two-temperature MRHD model is developed and numerical simulation of electromagnetic implosion of the electrically fired liners is fulfilled. Stage of the imploding plasma thermalization during interaction with a rigid wall is analyzed. Authenticity of the calculated results is confirmed by the way of comparison with calculated results by authors and results of experiments, carried out on a number of large-scale facilities.Possibility of development of continuous radiation sources radiating Prad > 1 TW at t = 10 ns pulse length and T = 100 eV brightness temperature is demonstrated. Principal possibility of control of the spectral composition of high-current discharge plasma radiation by means of varying of plasma element composition and time programming of energy contribution to plasma is shown.