Method to determine defect positions below a metal surface by STM

The oscillatory voltage dependence of the conductance of a quantum point contact in the presence of a single point-like defect has been analyzed theoretically. Such signals are detectable and may be exploited to obtain information on defect positions below a metal surface. Both tunnel junctions and ballistic contacts of adiabatic shape have been considered. The effect of quantum interference has been taking into account between the principal wave that is directly transmitted through the contact and the partial wave that is scattered by the contact and the defect. This effect leads to oscillations of the conductance as a function of applied voltage. We obtain the dependence of the period and amplitude of the conductance oscillations on the position of the defect inside the metal.Comment: 16 pages, 7 figure

Temperature-dependent quantum electron transport in 2D point contact

We consider a transmission of electrons through a two-dimensional ballistic point contact in the low-conductance regime below the 0.7-anomaly. The scattering of electrons by Friedel oscillations of charge density results in a contribution to the conductance proportional to the temperature. The sign of this linear term depends on the range of the electron-electron interaction and appears to be negative for the relevant experimental parameters.Comment: 10 pages, 5 figure

Secreted hydrolases from streptomycin-resistant strains of Bacillus intermedius

Alkaline phosphatase and serine proteinase have been isolated from streptomycin-resistant strains of Bacillus intermedius using ion-exchange, affinity and FPLC chromatography. Substrate blotting analysis and electrophoresis revealed two phosphatase forms with molecular weight of 40 and 50 kDa. The pH and temperature optima of phosphatase were at pH 9.5 and 50°C. The enzyme showed a broad substrate specificity. It was suggested that the two forms of phosphatase are the products of processing, in which serine proteinase is the participant. Two proteinase peaks with molecular weights of 29 and 33 kDa were isolated from B. intermedius S7, the first peak having only 5% of the activity of the second peak. The major peak was identical to serine proteinase described earlier. The minor peak was distinct from the major one by the pH-optima. Analysis of inhibitors' effects revealed that the minor peak also corresponded to serine proteinase

К 100-ЛЕТНЕМУ ЮБИЛЕЮ ПЕРВОЙ В МИРЕ КАФЕДРЫ РЕНТГЕНОЛОГИИ

The article reflects the stages of development of the first in the world department of radiology throughout the century. During the existence of the department, it was headed by eminent scientists. Under their leadership, the department staff made an invaluable contribution not only to the development of radiology as a science, but also to the development of teaching this specialty in the USSR. The traditions of innovation and teaching excellence laid down by the founders of the department are preserved and developed at the present stage.В статье отражены этапы развития первой в мире кафедры рентгенологии на протяжении века. За время существования кафедры ею руководили выдающиеся ученые. Под их руководством сотрудники кафедры внесли неоценимый вклад не только в развитие рентгенологии как науки, но и в становление преподавания этой специальности в СССР. Традиции новаторства и мастерства преподавания, заложенные основоположниками кафедры, сохраняются и развиваются на современном этапе

Secreted hydrolases from streptomycin-resistant strains of Bacillus intermedius

Alkaline phosphatases and serine proteinases have been isolated from the culture liquid of streptomycin-resistant strains of Bacillus intermedius using ion-exchange and affinity chromatography and FPLC. Substrate blotting and electrophoresis revealed two phosphatase forms with molecular masses of 40 and 50 kD. The enzyme had maximal activity at pH 9.5 and 50°C and could cleave the phosphate moiety from a range of substrates. It is suggested that both forms of the phosphatase are products of processing that involves a serine proteinase. Two proteinases, with molecular masses of 29 and 33 kD, were purified to homogeneity from the culture liquid of A. intermedius S7. The protein from the major peak was identical in its properties to an earlier described serine proteinase. The minor peak was 5% of the major one. These enzymes had different pH optima. Inhibitor analysis indicated that the minor peak is also a serine proteinase

Classification of human coronary atherosclerotic plaques with T1, T2 and Ultrashort TE MRI

Multicontrast MRI with T1, T2 and Ultrashort TE (UTE) sequences is used to image atherosclerotic plaque in human coronary arteries. MRI classification of the plaques is compared with their histological classification and found to correlate extremely well. The addition of UTE MRI adds significant value to the imaging of human coronary artery plaque by MRI

Enzymatic properties of thiol-dependent serine proteinase of Bacillus intermedius 3-19

Effects of a thiol-dependent serine proteinase of Bacillus intermedius on peptide substrates and insulin B-chain were studied. The enzyme preferably splits peptide bonds formed by carboxyl groups of hydrophobic amino acids. Ca2+ increases the thermal stability of the proteinase significantly. The kinetic characteristics of hydrolysis of Z-Ala-Ala-Leu-pNA by this enzyme was determined as Km = 1.25 mM and kcat = 0.15 sec-1. The enzyme has high stability to DMFA and isopropanol, and is able to catalyze peptide bond synthesis

Resonant multiple Andreev reflections in mesoscopic superconducting junctions

We investigate the properties of subharmonic gap structure (SGS) in superconducting quantum contacts with normal-electron resonances. We find two distinct new features of the SGS in resonant junctions which distinguish them from non-resonant point contacts: (i) The odd-order structures on the current-voltage characteristics of resonant junctions are strongly enhanced and have pronounced peaks, while the even-order structures are suppressed, in the case of a normal electron resonance being close to the Fermi level. (ii) Tremendous current peaks develop at $eV=\pm 2E_0$ where $E_0$ indicates a distance of the resonance to the Fermi level. These properties are determined by the effect of narrowing of the resonance during multiple Andreev reflections and by overlap of electron and hole resonances.Comment: 13 pages, 10 figure

Andreev reflection and order parameter symmetry in heavy-fermion superconductors: the case of CeCoIn5_5

We review the current status of Andreev reflection spectroscopy on the heavy fermions, mostly focusing on the case of CeCoIn$_5$, a heavy-fermion superconductor with a critical temperature of 2.3 K. This is a well-established technique to investigate superconducting order parameters via measurements of the differential conductance from nanoscale metallic junctions. Andreev reflection is clearly observed in CeCoIn$_5$ as in other heavy-fermion superconductors. The measured Andreev signal is highly reduced to the order of maximum $\sim$ 13% compared to the theoretically predicted value (100%). Analysis of the conductance spectra using the extended BTK model provides a qualitative measure for the superconducting order parameter symmetry, which is determined to be $d_{x^2-y^2}$-wave in CeCoIn$_5$. A phenomenological model is proposed employing a Fano interference effect between two conductance channels in order to explain both the conductance asymmetry and the reduced Andreev signal. This model appears plausible not only because it provides good fits to the data but also because it is highly likely that the electrical conduction occurs via two channels, one into the heavy electron liquid and the other into the conduction electron continuum. Further experimental and theoretical investigations will shed new light on the mechanism of how the coherent heavy-electron liquid emerges out of the Kondo lattice, a prototypical strongly correlated electron system. Unresolved issues and future directions are also discussed.Comment: Topical Review published in JPCM (see below), 28 pages, 9 figure