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Aim. The aim of our study was to assess the prevalence of contrast-induced nephropathy (CIN) in patients with chronic coronary artery disease (CAD) and its 1-year prognostic significance.Materials and methods. 462 patients with chronic CAD and indications to the interventions with intraarterial contrast media administration were included in the study. We conducted a prospective open cohort study (ClinicalTrials.gov NCT04014153). The primary endpoint was the development of CIN. The secondary endpoints were total mortality, cardiovascular mortality, myocardial infarction, stroke, gastrointestinal bleeding, acute decompensation of heart failure, coronary artery bypass grafting, repeat percutaneous coronary intervention.Results. 28 patients (6%) developed CIN. The rate of CIN in female patients was twice higher, than in males (9,29% vs. 4,66%). There was a trend towards less cases of CIN in patients without obesity (5,88% vs. 6,22%). CIN developed more frequently in patients with anemia (8,9% и 5,7%, р=0,3649, ОR 1,633,95% CI 0,6507-4,239). There was a trend to higher incidence of CIN in people with hyperuricemia (8% vs. 5,95%, р=0,6575, ОR 1,375,95% CI 0,3055-5,808). The rate of CIN in patients with diabetes mellitus was 2% higher, then without one. People, who suffered from myocardial infarction after 1 year of follow up, had the highest rate of CIN (26,7%), as well as patients with other major cardiovascular complications (18,1%). The rate of repeat percutaneous coronary interventions was 9,5%, the rate of acute decompensation of heart failure was 7%.Conclusion. The prevalence of CIN in patients with chronic CAD was 6%. After 1 year of follow up the rate of CIN was higher in patients who had myocardial infarction, repeat percutaneous coronary interventions and acute decompensation of heart failure.

Quantum effects in p-type Si0.2Ge0.8/Ge/Si0.2Ge0.8 heterostructure with an extremely high mobility of charge carriers μH = 1367000 cm2/(V ⋅ s) have been comprehensively studied. An analysis of Shubnikov–de Haas oscillations yielded effective mass of charge carriers, which proved to be very low, m* = 0.062m0, and the value of fluctuations of hole density along the channel δp = 3.5 ⋅ 109 cm–2. The fractional Hall effect (filling numbers 8/3, 7/3, 5/3, 4/3) observed at temperatures up to 5 K has been discovered in strong magnetic fields. The studies of quantum interference effects related to weak localization and electron-electron interaction between charge carriers, which have been conducted in such a high-mobility system for the first time, enabled calculation of spin splitting Δ = 1.07 meV and the Fermi-liquid coupling constant F 0 σ = − 0.12, which agree with results obtained earlier.Quantum effects in p-type Si0.2Ge0.8/Ge/Si0.2Ge0.8 heterostructure with an extremely high mobility of charge carriers μH = 1367000 cm2/(V ⋅ s) have been comprehensively studied. An analysis of Shubnikov–de Haas oscillations yielded effective mass of charge carriers, which proved to be very low, m* = 0.062m0, and the value of fluctuations of hole density along the channel δp = 3.5 ⋅ 109 cm–2. The fractional Hall effect (filling numbers 8/3, 7/3, 5/3, 4/3) observed at temperatures up to 5 K has been discovered in strong magnetic fields. The studies of quantum interference effects related to weak localization and electron-electron interaction between charge carriers, which have been conducted in such a high-mobility system for the first time, enabled calculation of spin splitting Δ = 1.07 meV and the Fermi-liquid coupling constant F 0 σ = − 0.12, which agree with results obtained earlier.

The article deals with the present state of the formalized description of a 3-dimensional geological model with the consideration of the problems arising from the increase in scale and the transition from the geological bodies distinguished by stratigraphic principle to those identified by lithology-stratigraphic and engineering-geological divisions. An approach to solving these problems is proposed. It is shown that the problem of correctly determining the sequence of occurrence of lithological-stratigraphic subdivisions can be solved as a problem of topological sorting of vertices of an oriented graph. For the first time, the requirements for non-local alignment of geological sections are set.

Purpose . The study is aimed at determining concentrations of the polycyclic aromatic hydrocarbons (PAHs) and at revealing their pattern distribution in the bottom sediments of the "river – sea" contact zone on the example of the Sevastopol Bay and the river Chernaya. Methods and Results . Granulometric composition of the bottom sediments was determined by the decantation and dispersion method. Identification and quantitative determination of PAHs were car- ried out by the high performance liquid chromatography method. The total PAHs content in the bottom sediments of the area under study varied from 12 to 670 ng/g of dry weight. The pollutant content was minimum in the river site beyond the geochemical barrier. In the area where the river Chernaya flows into the Sevastopol Bay, the PAHs content was 121 ng/g. The highest PAHs content was revealed in the Sevastopol Bay bottom sediments, more precisely, in 1.5 km southwest of the river Chernaya flowing into the bay. 14 PAHs were identified in the estuary zone of the river, 4 of them (naphthalene, 2-methylnaphthalene, fluorene, anthracene) were in the trace amounts. The maximum concentration (99%) of silty material was observed in the Sevastopol Bay water area. The silt frac- tions were distributed as follows: 20% – aleuritic-pelite fraction, 79% – pelitic-aleurite fraction. Directly in the area of the river inflow into the bay, accumulation of the sand fraction (7%) and the max- imum portion of pelitic silts were noted. Conclusions . The recorded values of PAHs corresponded to the natural non-toxic levels. PAHs identified in the bottom sediments of the river estuary zone are of the mixed, predominantly petrogenic origin. The obtained data show that in the conditions of the "river – sea" contact zone, the PAHs accumulation in general and their individual fractions were governed mainly by presence of silt in the bottom sediments.

This paper aims at determining the level of Laspi Bay’s pollution according to the main physical and chemical as well as microbiological parameters of water and sea bottom sediments. The following indicators of the ecological well-being of the water area were determined: physical and chemical indicators of sea bottom sediments, concentration of chloroform-extractable substances and total petroleum hydrocarbons, microbiological indicators in sea water and bottom sediments. Integrated sanitary and biological research of the Laspi Bay showed that, by the defined parameters, this coastal area can be characterized, in general, as relatively prosperous. However, a number of indicators (the content of total petroleum hydrocarbons, particularly in the bottom water layer, a relatively high concentration of heterotrophic bacteria in sea water and bottom sediments) indicate that this part of the water area, which previously was classified as standard clean, is exposed to a significant anthropogenic stress. The obtained results may be associated with intense development of the Laspi region observed in the recent years. Apparently, pollutants enter the aquatic environment of the Laspi Reserve coastal water area with sewage and other waters, whereas environmental parameters indicate a low level of their oxidation and self-purification.

The charge carrier overheating effect was studied in the p-type Si0.4Ge0.6/Ge/Si0.4Ge0.6 heterostructure with two subband occupy. The temperature dependences of hole-phonon relaxation time τ h - ph sat weak magnetic fields demonstrated transition of the 2D system from regime of “partial inelasticity” characterized by dependence τ h - ph − 1 ∝ T2 to regime of small-angle scattering, described by dependence τ h - ph − 1 ∝ T5 with temperature increase. But in higher magnetic fields the dependence τ h - ph − 1 ∝ T3 manifests itself on dependences τh-ph(Th-ph). The possible explanations of such dependences are discussed.PACS: 72.15.Lh Relaxation times and mean free path; 72.20. My Galvanomagnetic and other magnetotransport effects; 72.20. −i Conductivity phenomena in semiconductors and insulators.

Multisubband transport of the p-type Si₀.₄Ge₀.₆/Ge/Si₀.₄Ge₀.₆ heterostructure has been investigated by means of magnetotransport measurements at low temperatures and high magnetic fields. Two frequency Shubnikov–de Haas oscillations indicate occupation of two subbands. This allows us to determine the densities and mobilities of the charge carriers on each subband. Shubnikov–de Haas oscillations reveal two 2D conduction subbands with carrier effective masses of 0.112m₀ and 0.131m₀. The quantum Hall ferromagnetic states which results from the crossing of two Landau levels with opposite spin and different subband was observed in SiGe systems for the first time.

Life, relationships and working conditions of employees of the Sevastopol Biological Station in the first five years after the war (1945–1949) are described.

A brief overview of the work in the Atlantic, Indian and Pacific oceans in the period 1967–1988 is given. Data on the distribution patterns and abundance of microorganisms capable of using oil hydrocarbons as the single source of carbon and energy are given. The accumulation of oil hydrocarbons by marine organisms, the effect of thin suspension of deep-water (5000 m) bottom sediments and ferromanganese nodules on zooplankton, and the toxicity of artificial polymers for marine biota are discussed. The expediency of the resumption of similar work in the World Ocean in modern environmental conditions is expressed.

Oil and petroleum products are among the most common pollutants in the marine environment. One of the main difficulties in interpreting oil pollution data for the seas, especially in cases of low concentrations, is the natural biogenic origin of many hydrocarbons which are typical for the chemical composition of oil. The aim of the work was to determine the total content, distribution and main sources of hydrocarbons input in the water of the river–sea mixing zone (the Chernaya River) using gas chromatographic methods. Based on the analysis of diagnostic ratios, as well as the principal component analysis it has been established that the main source of hydrocarbon input to the estuarine zone of the Chernaya River can be considered as the autochthonous production, and the input of oil and petroleum products is the third most important source.

A geological fund may contain data from various sources that describe the same object, as well as from other arrays of information. Correct use of the fund data is secured by harmonization of the information. For effective functioning and satisfactory information service, a geological fund should be not only a library of digital data with information search but also a system of content-related information processing. A knowledge base in an information system is an integral part of a model of the surrounding world, which includes rules, algorithms, and their parameters that can be applied to the content of the database of the factual data on a subject area to solve special problems. This article discusses the concept of a knowledge base of a geological fund, its tasks, and ways of its organization and use. Two problems are considered in detail: control of information consistency and updating of derived data, particularly synthetic maps. A geodatabase of a project of large-scale geological mapping of Moscow, which contains over 90 000 drill logs of exploratory wells and digital map data of a structural-geodynamic map, four geological maps of various stratigraphic divisions, a hydrogeological map, and five synthetic maps of dangerous processes and engineering–geological zonation, is selected as an example.

Synthetic maps of integral natural and technogenic-natural hazard are used in various management procedures. The main possible goals are strategy planning for the territory development, decision-making for a placement or protection of infrastructure objects, and risk management.

Weak localization effects and the interactions of charge carriers are studied in two Si0.7Ge0.3/Si0.2Ge0.8/Si0.7Ge0.3 p-type heterostructures, where one or two quantum levels are filled, respectively. A weak localization effect for two-dimensional charge carriers is found to occur in weak magnetic fields when the spin-orbital and inelastic scattering times are close, which is indicative of splitting of the spin states under the influence of a perturbing potential related to the formation of a two-dimensional potential well (Rashba mechanism). In higher magnetic fields when one quantum level is occupied, interaction effects appear that are caused by Coulomb interactions with a scatterer. When the two quantum levels are occupied, the dominant mechanism is scattering on Friedel oscillations of the charge carrier density induced by an impurity electric field. In all regions, the quantum corrections are in good agreement with modern theoretical predictions.

The coastal zone of Sevastopol, especially the recreational part, feels great anthropogenic impact due to hosting a large number of tourists, but also because of the urban and stormwater discharge, containing oil hydrocarbons in its composition. Brown algae Cystoseira barbata forms vast underwater thickets here. Cut off from the substrate algae are at the edge of the water, mixed with coastal casts, resulting in secondary pollution of both coastline and coastal waters. At the same time freshly detached plants are used by representatives of different taxonomic groups and are actively involved in the food chain. In this context, the aim of this work is to study the lipid-hydrocarbon composition of Cystoseira from the coastal storm casts. The amount of oil hydrocarbons was determined by gravimetric method and the amount of lipids by color reaction with phospho-vanillin reagent. The results obtained indicate higher levels of chloroform-extracted substances, total lipids and oil hydrocarbons in macrophytes of Kruglaya Bay in comparison with the levels in water area of Park Pobedy. Onshore casts of Cystoseira may be the source of secondary pollution of the coastal waters by oil hydrocarbons.

Hole mobilities at low and room temperature (RT) have been studied for a strained sGe/SiGe heterostructure using standard Van der Pauw resistivity and Hall effect measurements. The range of magnetic field and temperatures used were - 14 T < B < + 14 T and 1.5 K < T < 300 K respectively. Using maximum entropy-mobility spectrum analysis (ME-MSA) and Bryan's algorithm mobility spectrum (BAMS) analysis, a RT two dimensional hole gas drift mobility of (3.9 ± 0.4) × 103 cm2/V s was determined for a sheet density (ps) 9.8 × 1010 cm− 2 (by ME-MSA) and (3.9 ± 0.2) × 103 cm2/V s for a sheet density (ps) 5.9 × 1010 cm− 2 (by BAMS).

Magnetotransport studies at low and room temperature are presented for two-dimensional hole gases (2DHG) formed in fully strained germanium (sGe) quantum wells (QW). Two designs of modulation doped heterostructure grown by reduced pressure chemical vapour deposition (RP-CVD) were used and included a normal structure (doping above the Ge channel and inverted structure (doping beneath the Ge channel). The mobility (μH) for the normal structure was measured to be 1.34×106 cm2/Vs with a sheet density (ps) of 2.9×1011cm-2at 1.5 K, and μH= 3970 cm2/Vs and ps ∼1×1011cm-2 for room temperature, determined from simulation using the Maximum Entropy-Mobility Spectrum Analysis (ME-MSA) method. For the inverted structure a μH of 4.96×105 cm2/Vs and ps of 5.25×1011cm-2was measured at 90 mK. From the temperature dependent amplitude of Shubnikov de Haas oscillations, the normal structure was found to have a very low effective mass (m*) value of 0.063 m0 and a ratio of transport to quantum lifetime (α) of ∼78. This extremely high α is indicative of the carrier transport being dominated by small angle scattering from remote impurities i.e. a sample having an extremely low background impurity level and very smooth hetero-interfaces. The inverted structure had an m*of 0.069 m0 and α ∼29, which also indicates exceedingly high quality material.

The use of Shubnikov-de Haas oscillations for determining effective mass is illustrated by a study of the magnetotransport properties of the two-dimensional hole gas in Si1− x Ge x (x = 0.13, 0.36, 0.95, 0.98) quantum wells. For some samples the data cannot be fitted to standard theoretical curves in which the scattering of charge carriers is described by the conventional Dingle factor. The reasons for the discrepancies between the experiment the theory are: (i) the effect of spin splitting on the amplitude of the peak in the SdH oscillations; (ii) extra broadening of the Landau levels attributable to an inhomogeneous distribution of the carrier concentration; (iii) the coexistence of short and long-range scattering potentials; and, (iv) population of the second energy level in the quantum well. Ways of calculating the effective hole masses m* for all these cases are presented and values of m* are found for the heterostructures studied here.

The magnetoresistance (MR) of a two-dimensional hole gas in a quantum well of compressively strained Si0.05Ge0.95 has been investigated as a function of temperature. The MR shows a maximum at intermediate magnetic fields between the regions of weak localization and the Shubnikov-de Haas oscillations, which is discussed in terms of a recent theoretical study of the electron-electron interaction effect by Sedrakyan and Raikh (SR). The magnetic field MR dependence is clearly observed to cross over from quadratic to linear at T=7.8 K and B≈0.3 T. It is shown that the SR theory provides a good description of both the measured quadratic and positive linear MR, but over estimates the field position of the MR maximum and does not account for the shift in position with temperature that is observed. Earlier theories of electron-electron interaction (by Altshuler and Aronov, Gornyi and Mirlin) show a better agreement with the experimentally observed behavior of the MR maximum, but fit the low field MR less accurately.

The results of analysis of oscillations of an offshore oil and gas production platform, caused by seismic and other impacts (ice-field motion, storm wave impact, ship impact on platform supports, mechanism operations, etc.) are given. The analysis has been based on mathematical modeling of various impacts. Specific features of the inducement of platform mechanical oscillations as a function of the type of impact have been revealed, and the qualitative distinctions of platform oscillations under different impacts are described, allowing one to determine accelerometer-mounting sites for revealing seismic events by changes in acceleration on the platform.

The effect of charge carrier overheating is studied in the p-type Si/Si(0.87)Ge(0.13)/Si heterostructure. The hole temperature T(h) can be calculated using three different methods: From a comparison of the changes in the amplitude of the Shubnikov-de Haas oscillations under the influences of temperature and current, from a comparison of the change of phase relaxation time in the weak localization effect obtained at different temperatures and minimum current and at a given temperature but at different values of current, and from a comparison of the temperature and current dependence of the sample resistance. The temperature dependences values of T(h) obtained using three different methods were identical and exhibit transition of the two-dimensional system under study from the regime of "partial inelasticity" to that of small angle scattering at temperature lowering.

Microminiature Hall probes (MHP) may be used as magnetic field transducers, with virtually no change of sensitivity with temperature, for applications at room and cryogenic temperatures. The probes have a nominal active sensing area from 90 × 90 μm down to 20 × 20 μm and are based on Sn-doped n-InSb/i-GaAs MBE-grown heterostructures. MHPs were intensively tested in static (up to 14 T) and pulsed magnetic fields and shown to be appropriate for various applications in the temperature range 2–300 K and in pulsed magnetic fields up to 87 T. The latest version of these probes, with overall cross-section thickness-width dimensions of 150 × 750 μm, are the smallest encapsulated Hall probes currently available and can be placed in areas not previously accessible to commercial packaged or unpackaged sensors.

The Shubnikov-de Haas oscillations of the conductivity of a two-dimensional gas of holes in quantum wells consisting of pure germanium and silicon with low germanium content (13%) are analyzed to determine the effective masses and the g factor in these regions. The magnetic-field dependences of the resistivity rho(xx) obtained at temperatures from 33 mK to 4 K in magnetic fields up to I I T are used for the analysis. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3075945]

Low-temperature conductance mechanism in low-density Si/SiGe heterostructures in high magnetic fields (ultra-quantum limit) is studied using AC and DC transport measurements. Evidence of the Wigner crystal in this regime is given. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Complex high-frequency (HF), σAC = σ1 − iσ2, and static, σDC, conductivities, as well as current-voltage characteristics, have been measured in p-Si/SiGe heterostructures with a low hole density (p = 8.2 × 1010 cm−2) at temperatures T = 0.3–4.2 K in the ultraquantum limit, when the filling factor is v < 1. In order to determine the components of the HF conductivity, the acoustic contactless method in the “hybrid configuration” is used, when the surface acoustic wave propagates on the surface of the LiNbO3 piezoelectric and the heterostructure is pressed to the surface by a spring. The conductivities σ1 and σ2 are determined from the damping and velocity of the surface acoustic waves that are measured simultaneously with varying the magnetic field. The revealed HF conductivity features—σ1 ≫ |σ2|, the negative sign of σ2, the threshold behavior of the current-voltage characteristic, and the dependence I ∝ exp(-A/V 0.3) in the subthreshold region—indicate the formation of a pinned Wigner crystal (glass) in the ultraquantum limit (T = 0.3–0.8 K, B > 14 T).

This paper describes an application of the geographic information system (GIS) technology to a ground stability assessment in the karst area of Dzerzhinsk, Russia. In the stability analysis, the groundwater level changes in the karst aquifer could cause suffosion sinkholes when the gravitational force was greater than the soil strength. The GIS technology was used to combine various data and to delineate the zones of potential gravitational collapse and suffosion collapse in the area.

229 The most important trend in metallurgy and machine building is the introduction of materials with improved operational properties, so that components are able to withstand high-temperature oxidation (up to 1100 ° C) and intense abrasive and impact-abrasive wear. The material used to manufacture gratings and sintering cars at sinter plants must be characterized by high strength, thermal stability, and wear resistance. These requirements are best met by wear-resistant chromium-bearing cast iron, which is studied in the present work.

Measurements of the Hall and dissipative conductivity of a strained Ge quantum well on a SiGe/(001)Si substrate in the quantum Hall regime are reported. We find quantum Hall states in the Composite Fermion family and a precursor signal at filling fraction $\nu=5/2$. We analyse the results in terms of thermally activated quantum tunneling of carriers from one internal edge state to another across saddle points in the long range impurity potential. This shows that the gaps for different filling fractions closely follow the dependence predicted by theory. We also find that the estimates of the separation of the edge states at the saddle are in line with the expectations of an electrostatic model in the lowest spin-polarised Landau level (LL), but not in the spin-reversed LL where the density of quasiparticle states is not high enough to accommodate the carriers required., Comment: 5 pages, 4 figures, supplemental material 2 pages, 1 figure

Si/SiGe graded buffer 6 μm/Si0.4Ge0.6 2 μm (CVD)/Si0.4Ge0.6 200 nm (MBE)/Ge t/Si0.4Ge0.6 20 nm/Si 2 nm heterostructures with Ge channel thicknesses t = 16 nm and 20 nm were grown by a method of hybrid epitaxy and annealed ex situ at 650 °C under dry N2. As grown and annealed samples were measured using Rutherford backscattering. The 1H experiments at different proton energies allowed the thick linearly graded SiGe buffer to be analysed along with the uniform SiGe layer terminating the linearly graded region. 4He grazing angle experiments were sensitive to the thinner top layers, enabling the Ge channel thickness, composition and roughness to be determined. However, the depth resolution at the Ge channel was not good enough to determine if the channel layer consisted of pure Ge, or contained a residual Si content (few at.%), inherent to the method of growth. Complementary X-ray diffraction reciprocal space maps led to a high accuracy (∼1%) determination of the Si content of the channel, as well as the strain. Other layers in the structure were also accessible. Cross sectional transmission electron microscopy (XTEM) was also performed. In this paper we show how the combination of all these techniques leads to the complete structural characterization of these samples.

The weak localization and interaction effects for charge carriers in a two-dimensional hole gas in a pure germanium quantum well in a SiGe∕Ge∕SiGe heterostructure with a hole density of 5.68×1011cm−2 and mobility of 4.68×104cm2V−1s−1 are investigated. The resistance measurements were made at temperatures from 46mKto10K and magnetic fields up to 15T. The magnetic-field dependence of the resistivity exhibits Shubnikov-de Haas oscillations and quantum Hall effect steps. At very low magnetic fields (B

The Shubnikov–de Haas oscillations in a two-dimensional hole gas in a quantum well of pure germanium in a SiGe∕Ge∕SiGe heterostructure with a hole concentration pH=5.68×1011cm2 and mobility μ=4.68×104cm2V−1s−1 are investigated in magnetic fields up to 15 T at temperatures from 40 mK to 4 K. The observed deviation from the known relation describing the conductivity oscillations in the Shubnikov–de Haas effect are explained by additional broadening of the Landau levels due to the existence of a nonuniform distribution of the concentration of charge carriers, and, accordingly, of their energy, in the plane of the two-dimensional gas. It is assumed that the latter is due to natural atomic-step variations of the well width. The effective hole mass (m*=0.112m0) is determined from the temperature dependence of the oscillation amplitude, and its dependence on magnetic field is used to determine the quantum scattering time and the value of the carrier concentration fluctuations.

Strained Ge p-channel heterostructures have been realized by hybrid-epitaxial growth. Strain-tuning Si0.4Ge0.6 virtual substrates were grown by ultra-high vacuum chemical vapour deposition and active layers were deposited by solid-source molecular beam epitaxy at low temperature. Following ex situ annealing, Hall effect measurements revealed a hole mobility of 1900 cm2 V−1 s−1 at 300 K (27 000 cm2 V−1 s−1 at 10 K), with a density of 1.8 × 1012 cm−2, giving a conductance in excess of current Ge heterostructures. Using a maximum-entropy mobility-spectrum analysis, 1.0 × 1012 cm−2 of these holes were found to have a mobility of 2700 cm2 V−1 s−1 at 300 K.

We have developed a model of the high-current breakdown of the integer quantum Hall effect, as measured in contactless experiments using a highly-sensitive torsion balance magnetometer. The model predicts that, for low-mobility samples, the critical current for breakdown should decrease linearly with temperature. This prediction is verified experimentally with the addition of a low-temperature View the MathML source saturation of the critical current. It is shown that this saturation is consistent with quasi-elastic inter-Landau-level scattering when the maximum electric field in the sample reaches a large enough value.

Microminiature Hall probes with sensitive area down to 33×115 μm and based on n-InSb/i-GaAs optimized Sn-doped MBE-grown heterostructures are reported. The “metallurgical” thicknesses of the n-InSb epilayers lie in the range dm=1.1– 10.5 μm giving room-temperature mobilities of (9–15) ×10 3 cm 2 / Vs with carrier densities of (0.96–2.56) ×10 18 cm −3 . Characterization of the devices was performed by magnetotransport measurements in quasi-static and pulsed magnetic fields. In the temperature range 1.1– 300 K and in magnetic fields up to 12 T (static) and up to 52 T (pulsed, τ=120 mS ), transport measurements yield remarkable linearity of the Hall voltage up to 52 T and sensitivity, as well as demonstrating the high-temperature stability of the Hall voltage, the offset voltage and the device resistivity. No significant effect of the high current up to 150 mA on either the sensitivity or the resistivity is observed.

For the first time, we have demonstrated the reduced low-frequency (LF) noise in sub-μm metamorphic high Ge content p-Si 0.3 Ge 0.7 MOSFETs in comparison with p-Si MOSFETs at 293 K. Three times lower LF noise over 1–100 Hz range at V DS =−50 mV and V G − V TH =−1.5 V was measured for the 0.55 μm effective gate length p-Si 0.3 Ge 0.7 MOSFET compared with p-Si MOSFET. Over three times drain current enhancement in saturation region of output current–voltage characteristics at V DS =−2.5 V for a 0.55 μm p-Si 0.3 Ge 0.7 MOSFET in comparison with p-Si MOSFET is observed.

Magnetotransport at fields up to 500 mT and LF-noise characteristics are reported for miniature magnetoresistors with ferrite concentrators based on Sn-doped n-InSb/i-GaAs heterostructures grown by MBE. The thickness of the InSb epilayers lie in the range 0.55-1-5 μm giving room temperature mobilities of 2.5-5.5 m 2 V - 1 s - 1 with carrier densities of (0.5-1.5) x 10 1 7 cm - 3 . The room temperature magnetoresistance (MR) for our two terminal devices could be as high as 115% at 50 mT which is comparable to the extraordinary MR (ExMR) recently reported in microscopic composite van der Pauw disks four terminal devices [Science 289 (2000) 1530]. In addition, a high signal-to-noise ratio and a good temperature stability of R(B)/R 0 = 0.5-0.83% K - 1 was observed for B < 60 mT (below the saturation field Brat for ferrite). Device resistance stability R 0 (T) was equal to 0.27-0.66% K - 1 in zero field with a nominal device resistance R 0 = 197-224 Ω for DC currents in the range I = 0.01-1.0 mA. The minimum detectable magnetic field is estimated from the reduced differential MR (∂R/∂B)/R = 2000% T - 1 at B = 31 mT and normalised 1/f current noise power spectral density measured at the same field. The resolution limit B m i n = 2.6 nT at 10 2 Hz and B m i n = 0.82 nT at 10 3 Hz. These resolution limits are seven times better than those recently reported for the same material n-InSb/i-GaAs and ferrite fabricated Hall sensors [Magnetotransport and Raman characterization of n-InSb/i-GaAs epilayers, for Hall sensors applications over extremely wide ranges of temperature and magnetic field, Proceedings NGS 10, IPAP Conference Series 2, IPAP, Tokyo, 2001, pp. 151-154].

The electronic subband structure of carriers in bismuth-like cylindrical nanowires is investigated analytically, using an anisotropic effective mass model. Quantum confinement effects are found to be significantly enhanced over the results of a quasi-isotropic approach, due to the correct consideration of both the mass anisotropy and the boundary shape of the wire. The size quantization problem for a carrier with anisotropic effective mass parameters in a cylindrical well is shown to be equivalent to that of a carrier with some isotropic effective mass in an elliptical well. Detailed study of the energy levels reveals their orbital degeneracy is lifted by the elliptic symmetry, where the degree of ellipticity corresponds to the mass anisotropy. Carrier motion is analysed by analogy to the geometrical optics of elliptic waveguides, with bounding caustic curves defining two groups inside the wire that correspond to 'whispering gallery' and 'jumping ball' modes. The additional confinement, arising from the mass anisotropy, leads to larger critical wire diameters for the semimetal-to-semiconductor transition, which is investigated for wires of different crystallographic orientation.

The magnetic-field dependence (up to 110 kOe) of the resistance of Si0.7Ge0.3/Si0.2Ge0.8/Si0.7Ge0.3 with a 2D hole gas in a Si0.2Ge0.8 quantum well is measured in the temperature range 0.335–10 K and in a range of variation of the currents from 100 nA to 50 μA. Shubnikov–de Haas oscillations are observed in the region of high magnetic fields, and in the low-field region H⩽1 kOe a positive magnetoresistance is observed which gives way to a negative magnetoresistance as the field is increased. This peculiarity is explained by effects of weak localization of the 2D charge carriers under conditions when the spin–orbit scattering time τso is close to the inelastic scattering time τφ, and it is evidence of a splitting of the spin states under the influence of a perturbing potential due to the formation of a two-dimensional potential well (the Rashba mechanism). Analysis of the weak localization effects gave the values of the characteristic relaxation times as τφ=7.2T−1×10−12 s and τso=1.36×10−12 s. From these c...

The magnetic flux dynamics was investigated in a textured Bi2Sr2CaCu2O8+δ sample using a miniature Hall probe placed on the surface of the superconductor. The process of magnetic flux penetration into the superconductor was found to have a complex structure and consist of two processes with different time scales. The first one has a length of tens of microseconds and is considered as locally adiabatic. The second one has a length comparable with the time of thermal diffusion. The importance of the above two processes in the development of magnetic instability is analyzed.

We have monitored peculiarities of the dynamics of catastrophic avalanches of the magnetic flux in LTSC and HTSC samples. The observed oscillation mode in the mixed state of superconducting Nb-Ti samples as a result of catastrophic avalanches was discussed in terms of a theoretical model which takes into account the inertial properties of the vortex matter.

High resolution X-ray diffraction was used to study the thermal stability and strain relaxation mechanisms in p-type modulation doped Si 1− x Ge x /Si 1− y Ge y /Si(001) heterostructures on virtual substrates. Ex-situ post-growth furnace thermal treatments were done in a N 2 ambient at 600, 700 and 750 °C. It was found that the high temperature annealing leads to the full relaxation of the intermediate part of the virtual substrate (corresponding to the Ge composition range of y =0.17–0.27). Both the uppermost and lowermost parts of the virtual substrate regions with, respectively, y Ge =0.27–0.35 and 0.10–0.17, were found to be not fully relaxed even after annealing at 750 °C. The use of the Hotbird X-ray diffractometer with its powerful rotating anode source allowed us to reveal and study the very weak intensity scattering from a 4nm thick Si 0.2 Ge 0.8 channel. The increase of the annealing temperature leads to a broadening of the channel layer with a decreasing of its Ge concentration though remaining fully strained.

We briefly review recent work on enhancements in transconductance, maximum voltage gain, carrier mobility and velocity overshoot in Si/Si0.64Ge0.36/Si p-channel metal-oxide semiconductor devices and then discuss the superior 1/f noise properties in more detail. The results indicate the growth and processing chanllenges which must be met in order to improve device performance.