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Abstract—The influence of annealing at 600°C on the mechanical and thermomechanical characteristics of a Ti50Pd30Ni20 alloy with high-temperature shape memory effect (SME) is studied. The best strength (σu = 1030 ± 140 MPa) and plastic ( = 11.5 ± 6.0%, δres = 6 ± 4%) characteristics have been obtained after annealing at 600°C. The maximum thermally recoverable strain (εSME = 4.3%) and the maximum degree of shape recovery (ηSME = 67%) are achieved after annealing at 600°C after preliminary induced tensile deformation at temperatures td =235–230°C and a strain rate ≈ 2.8 × 10–3 s–1; in this case, the reverse martensitic transformation temperatures characterizing the main shape recovery are AsSME = 220°C and AfSME = 249°C. Taking into account the studies carried out before, we found that the martensitic transformation temperatures increase almost linearly and, conversely, the SME and the degrees of shape recovery decrease as the titanium nickelide is alloyed with palladium in the content range from 30 to 50 at %. Linear regression equations are derived. The results obtained are used for designing safety devices of, e.g., crosscutting and pushing types. [ABSTRACT FROM AUTHOR]

A dual‐band shared‐aperture antenna with a frequency ratio of 3 is presented in the letter. A low‐band antenna consists of two printed dipoles. An artificial magnetic conductor (AMC) is used to reduce the height of the low‐band antenna. A high‐band antenna consists of four printed dipoles. It is placed between the AMC elements and the antenna ground plane. The AMC elements and antenna ground plane form a Fabry–Perot cavity and allow increasing gain of the high‐band antenna. An additional structure is inserted between the antenna ground plane and the AMC elements to decrease heights of the Fabry–Perot cavity and the high‐band antenna simultaneously. The total size of the proposed antenna is 1.02λL × 1.02λL × 0.103λL (λL is the central wavelength of the low operating band). Simulated and measured results show that the designed antenna has 57% and 16.7% bandwidths in the low‐ and high‐frequency bands. [ABSTRACT FROM AUTHOR]

Glycolipids are components of the cell membrane capable of transport both from it and in the opposite direction, i.e. from the intercellular matrix to the membrane. The latter opens up the possibility of studying the functioning of glycolipids by their inserting into the cell membrane. In practice, synthetic analogs of glycolipids are significantly more suitable than natural glycolipids for such application, because one can vary properties, modifying their structure, as well as conjugating to other bioactive components, in addition to glycans. This study describes the synthesis of the eight glycolipids containing the same glycan part (A (type 2) tetrasaccharide) but varying in the composition of the lipid part as well as analogs of glycolipids carrying several identical carbohydrate moieties. The resulting series of synthetic analogs of glycolipids opens up the possibility of studying the immunological presentation of the glycan and its recognition by antibodies in the real microenvironment (glycocalyx) of a living cell. [ABSTRACT FROM AUTHOR]

In spin noise spectroscopy, the magnetic susceptibility spectrum is known to be provided by the spin-system untouched by any external perturbation, or, better to say, disturbed only by its thermal bath. We propose a new version of spin noise spectroscopy, with the detected magnetization (Faraday-rotation) noise being "stimulated" by an external fluctuating magnetic field with a quasiwhite spectrum. An experimental study of the stimulated spin noise performed on a BaF 2 : U 3 + crystal in a longitudinal magnetic field has revealed specific features of this approach and allowed us to identify the Van-Vleck and population-related contributions to the AC susceptibility of the system and to discover unusual magnetic-field dependence of the longitudinal spin relaxation rate in low magnetic fields. It is shown that spectra of the stimulated and spontaneous spin noise, being both closely related to the spin-system magnetic susceptibility, are still essentially different. Distinctions between the two types of the spin-noise spectra and two approaches to spin noise spectroscopy are discussed. [ABSTRACT FROM AUTHOR]

The properties of an Ni49.5Ti48Hf2.5 high-temperature shape memory effect alloy are comprehensively studied on samples made of a 2.34-mm-thick strip after high-temperature vacuum annealing (850°C, 1 h). The elemental, phase compositions and structure of the alloy are analyzed. The results of studying the phase transformation temperatures and the mechanical and thermomechanical characteristics of the alloy are presented. The results of studying the local phase composition of the alloy samples demonstrate that their matrix is formed by a solid solution of alloy elements (Ti, Ni, Hf). X-ray diffraction analysis demonstrates that the main phase of the samples is titanium nickelide in the low-temperature TiNi martensitic state (B19') with a monoclinically distorted orthorhombic crystal lattice. The best average shape memory characteristics (εSME = 4.4%, ηSME = 53%) are obtained for alloy samples subjected to preliminarily induced total strain εt = 11% in the temperature Td range from –5 to 23°C at a strain rate ≈ 2.8 × 10–3 s–1. Here, the average temperatures of the onset and end of the main shape recovery are AsSME = 133°C and AfSME = 149°C. These thermomechanical characteristics are acceptable for the alloy chosen to create safety devices of, e.g., a pushing type. [ABSTRACT FROM AUTHOR]

When studying the spin-noise-induced fluctuations of Kerr rotation in a quantum-well microcavity, we have found a dramatic increase of the noise signal (by more than two orders of magnitude) in the vicinity of anti-crossing of the polariton branches. The effect is explained by nonlinear optical instability of the microcavity giving rise to the light-power-controlled amplification of the polarization noise signal. In the framework of the developed model of built-in amplifier, we also interpret the nontrivial spectral and intensity-related properties of the observed noise signal below the region of anti-crossing of polariton branches. The discovered effect of optically controllable amplification of broadband polarization signals in microcavities in the regime of optical instability may be of interest for detecting weak oscillations of optical anisotropy in fundamental research and for other applications in optical information processing. [ABSTRACT FROM AUTHOR]

The properties of the Ti50Pd40Ni10 (at %) alloy showing the high-temperature shape memory effect are studied in detail using samples made of a 5.86 mm bar under various conditions of annealing and induced deformation. The data on the phase transformation temperatures and the mechanical and thermomechanical characteristics of the alloy are obtained. The range of phase transformations occurs in the range from Mf = 360°C to Af = 439°C. These are acceptable values for creating the required safety device. The maximum values of the shape memory effect and the degree of shape recovery are 2.4 and 43%, respectively. This is not sufficient to create a functional security device. Thus, the selection of annealing modes and conditions for inducing deformation are not a successful way to substantially increase the thermomechanical characteristics of the alloy. Higher values of thermomechanical characteristics have previously been obtained using samples cut from a strip with a thickness of 2.04 mm. Therefore, operating elements of safety devices designed for nuclear power facilities will be further manufactured from the strip. [ABSTRACT FROM AUTHOR]

We present results of numerical simulations of the kinetics of exciton-exciton annihilation of weakly localized one-dimensional Frenkel excitons at low temperatures. We find that the kinetics is represented by two well-distinguished components: a fast short-time decay and a very slow long-time tail. The former arises from excitons that initially reside in states belonging to the same localization segment of the chain, while the slow component is caused by excitons created on different localization segments. We show that the usual bimolecular theory fails in the description of the behavior found. We also present a qualitative analytical explanation of the nonexponential behavior observed in both the short- and the long-time decay components. Finally, it is shown that our theoretical estimate for the annihilation time of the fast component is in good agreement with data obtained from transient absorption experiments on J-aggregates of pseudoisocyanine. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

It is shown analytically that the introduction of the law 'On the Management of Radioactive Waste' and the start of the active phase of the decommissioning of NPP have changed goal-setting in the waste management system and actualized the task of modernizing the system. The necessary conditions for improving the technological platform for managing radioactive waste at NPP (R&D status, experience in using in practice the advances made in science, commercial accessibility of the required materials and technical means) have mostly been formulated. Modernization of the waste management system, as a rule, does not require radical revisions of the design solutions or high material costs. [ABSTRACT FROM AUTHOR]

We exploit the potential of the spin noise spectroscopy (SNS) for studies of nuclear spin dynamics in n-GaAs. The SNS experiments were performed on bulk n-type GaAs layers embedded into a high-finesse microcavity at negative detuning. In our experiments, nuclear spin polarisation initially prepared by optical pumping is monitored in real time via a shift of the peak position in the electron spin noise spectrum. We demonstrate that this shift is a direct measure of the Overhauser field acting on the electron spin. The dynamics of nuclear spin is shown to be strongly dependent on the electron concentration. [ABSTRACT FROM AUTHOR]

The optical gyrotropy noise of a high-finesse semiconductor Bragg microcavity with an embedded quantum well (QW) is studied at different detunings of the photon mode with respect to the QW exciton resonances. A strong suppression of the noise magnitude for the photon mode frequencies lying above exciton resonances is found. We show that such a critical behavior of the observed optical noise power is specific to asymmetric Fabry-Perot resonators. As follows from our analysis, at a certain level of intracavity loss, the reflectivity of the asymmetric resonator vanishes, while the polarimetric sensitivity to the gyrotropy changes dramatically when moving across the critical point. The results of model calculations are in a good agreement with our experimental data on the spin noise in a single-quantum-well microcavity and are confirmed also by the spectra of the photoinduced Kerr rotation in the pump-probe experiments. [ABSTRACT FROM AUTHOR]

We report on an experimental observation of spin noise in a single semiconductor quantum well embedded into a microcavity. The great cavity-enhanced sensitivity to fluctuations of optical anisotropy has allowed us to measure the Kerr rotation and ellipticity noise spectra in the strong-coupling regime. The spin noise spectra clearly show two resonant features: a conventional magnetoresonant component shifting towards higher frequencies with a magnetic field and an unusual "nonmagnetic" component centered at zero frequency and getting suppressed with an increasing magnetic field. We attribute the first of them to the Larmor precession of free electron spins, whereas, the second one is presumably due to hyperfine electron-nuclei spin interactions. [ABSTRACT FROM AUTHOR]