ERD studies of D-ion depth distributions after implantation into some pure metals and alloys

This paper presents a report on experimental results of depth distributions of deuterium ions implanted with 25 keV energy at a fluence interval of (1.2–2.3) × 10²² m⁻² into samples of pure metals (Cu, Ti, Zr, V, Pd) and diluted Pd alloys (Pd-Ag, Pd-Pt, Pd-Ru, Pd-Rh). The post-treatment depth distributions of deuterium and hydrogen atoms were measured within a few hours after implantation with the use of elastic recoil detection (ERD) analysis. After three months the measurements were repeated. The comparison of the obtained results in both series of studies allowed us to make an important observation of the desorption rates of implanted deuterium atoms from pure metals and diluted Pd alloys. The maximum measured concentrations of deuterium atoms in pure Zr and Ti foils with relatively small desorption rate of deuterium atoms within three months after implantation were observed. Also a very high spreading of deuterium atom distributions was observed in all the measured pure metals and alloys. It can be explained by the large diffusion coefficients of deuterium and extremely fast kinetics.     

Ground-state correlation properties of charged bosons trapped in strongly anisotropic harmonic potentials

The core width and Peierls barrier and stress for Shockley partials in InP have been investigated using the improved P-N theory. The core width of 90° partial is about 1.6 times wider than that of 30° partial, and both of them are very narrow: core width ξ < 0.5b. In calculating the Peierls barrier and stress, the contribution from stain energy ignored by classical P-N theory has been considered. The calculated results show that when the dislocation moves, both the misfit and strain energies change periodically. They cancel each other due to the same order but opposite phases. Accordingly, the Peierls barrier and stress calculated from improved P-N theory are much lower than those calculated from the classical P-N theory. The Peierls barrier for 90° and 30° partials obtained by us is respectively about  ~0.047 eV/Å and 0.044–0.075 eV/Å, the Peierls stress is respectively about 3.7–5.0 GPa and 4.2–6.9 GPa.     

Effect of masker-fringe onset asynchrony on overshoot (L)

The study examines how overshoot is influenced by masker-signal onset asynchrony when the masker contains frequencies above or below the signal frequency. Masked thresholds were measured for a 2-ms tone at 5 kHz. The measurements were made in a reference condition with a narrow center-band (CB) noise masker (4590-5464 Hz), and in conditions with either a low-fringe (1900-4590 Hz) or a high-fringe noise band (5500-11 000 Hz) added to the CB. The signal always came on 2 ms after the onset of the CB. The time interval, between fringe and signal onsets varied from -98 ms (signal onset before fringe onset) to +502 ms (signal onset after fringe onset). Results show that overshoot is largest, 8-11 dB, for a high fringe with onset occurring between 8 ms before the signal onset and 12 ms after it. Thus, pronounced overshoot is observed even when the high fringe is gated on after the signal's offset. Low fringes produce no more than 4 dB of overshoot, much less than high fringes produce. The finding of pronounced overshoot elicited by a high fringe presented shortly after the end of the signal suggests that overshoot is governed, at least in part, by central mechanisms.     

Current-driven destabilization of both collinear configurations in asymmetric spin valves

Spin-transfer torque in spin valves usually destabilizes one of the collinear configurations (either parallel or antiparallel) and stabilizes the second one. Apart from this, balance of the spin-transfer and damping torques can lead to steady precessional modes. In this Letter we show that in some asymmetric nanopillars, spin current can destabilize both parallel and antiparallel configurations. As a result, stationary precessional modes can occur at zero magnetic field. The corresponding phase diagram as well as frequencies of the precessional modes have been calculated in the framework of macrospin model. The relevant spin-transfer torque has been calculated in terms of the macroscopic model based on spin diffusion equations.     

Symmetric Minkowski planes ordered by separation

In Karzel et al. (J. Geom. 99: 116–127, 2009) we introduced for a symmetric Minkowski plane ${ {\mathfrak M} := (P,\Lambda,{\mathfrak G}_1,{\mathfrak G}_2) }$ an order concept by the notion of an orthogonal valuation for the circles of Λ and showed that there is a one to one correspondence between the valuations and the halforderings of the accompanying commutative field. Here we consider an order concept which is based on the notion of separation for quadruples of concyclic points and establish the connections between these two notions. Our main result (cf. Theorem 3.3) states that these concepts are equivalent.     

The reduction of the misfit dislocation in non-doped AlAs/GaAs DBRs

The non-doped AlAs/GaAs distributed Bragg reflectors (DBRs) with density of misfit dislocation (MD) close to zero had been obtained. The reduction of MD density was achieved by increasing temperature distribution homogeneity on the growing crystal in consequence of higher rotation rate of the wafer. Two structures of DBR were crystallized using molecular beam epitaxy (MBE) under the same optimal growth condition. The growth runs differ only in the rotation rate of the wafers. X-ray topograph showed no residual MDs in case of faster rotation. The DBR structure with residual MD density is still highly strained. No additional relaxation process has occurred, what was confirmed by an angular position of DBR zeroth-order peak on high-resolution X-ray diffractometry (HRXRD) rocking curve.     

Electronic and vibrational contributions to first hyperpolarizability of donor-acceptor-substituted azobenzene

In this study we report on the electronic and vibrational (hyper)polarizabilities of donor-acceptor-substituted azobenzene. It is observed that both electronic and vibrational contributions to the electric dipole first hyperpolarizability of investigated photoactive molecule substantially depend on the conformation. The contributions to the nuclear relaxation first hyperpolarizability are found to be quite important in the case of two considered isomers (cis and trans). Although the double-harmonic term is found to be the largest in terms of magnitude, it is shown that the total value of the nuclear relaxation contribution to vibrational first hyperpolarizability is a result of subtle interplay of higher-order contributions. As a part of the study, we also assess the performance of long-range-corrected density functional theory in determining vibrational contributions to electric dipole (hyper)polarizabilities. In most cases, the applied long-range-corrected exchange-correlation potentials amend the drawbacks of their conventional counterparts.     

Current trends in solid-phase microextraction (SPME) fibre coatings

This critical review presents information on known and innovative approaches to the manufacture of fibre coatings used in solid-phase microextraction (SPME). The properties, advantages and drawbacks of the different types of commercially available SPME fibre coatings are discussed in detail, as are those of novel types of coatings and the methodologies of their preparation. The applications of fibre coatings in the solid-phase microextraction of a broad spectrum of analytes are analysed, with particular emphasis on the sampling of polar analytes from polar matrices (174 references).     

Fluorescence Imaging of Heat-Stress Induced Mitochondrial Long-Term Depolarization in Breast Cancer Cells

Various thermotherapies are based on the induction of lethal heat in target tissues. Spatial and temporal instabilities of elevated temperatures induced in therapy targets require optimized treatment protocols and reliable temperature control methods during thermotherapies. Heat-stress induced effects on mitochondrial transmembrane potentials were analyzed in breast cancer cells, species MX1, using the potential sensor JC-1 (Molecular Probes, Invitrogen, Germany). Potential dependant labeling of heat-stressed cells was imaged and evaluated by fluorescence microscopy and compared with control cells. JC-1 stains mitochondria in cells with high mitochondrial potentials by forming orange-red fluorescent J-aggregates while in cells with depolarized or damaged mitochondria the sensor dye exists as green fluorescent monomers. In MX1 cells orange-red and green fluorescence intensities were correlated with each other after various heat-stress treatments and states of mitochondrial membrane potentials were deduced from the image data. With increasing stress temperatures the intensity of red fluorescent J-aggregates decreased while the green fluorescence intensity of JC-1 monomers increased. This heat-stress response happened in a nonlinear manner with increasing temperatures resulting in a nonlinear increase of red/green fluorescence ratios. These data indicated that mitochondria in MX1 cells were increasingly depolarized in response to increasing ambient temperatures.     

Trianglamines--readily prepared, conformationally flexible inclusion-forming chiral hexamines

Trianglamines, macrocyclic heteraphanes, were readily synthesised through a [3+3] cyclocondensation of (R,R)-1,2-diaminocyclohexane with terephthalaldehyde, followed by NaBH4 reduction and N-alkylation. The macrocyclic ring shows a remarkable ability to change its conformation, as a consequence of rotation about the C-N bonds or nitrogen inversion due to protonation or N-alkylation, as revealed by circular dichroism spectra, computational modelling and X-ray diffraction analysis. The flexible natures of the trianglamine macrocycles allow ready accommodation of a variety of guest molecules to form crystalline inclusion complexes of highly diversified interpenetrating structures.