De Haas-van Alphen effect in unconventional superconductors

A theory of the de Haas-van Alphen effect in type-II p-wave and D-wave superconductors (the latter corresponds to the B _1g one-dimensional representation of group D _4h ) has been developed. Solutions for the order parameter and density of quasiparticle states near the upper critical field have been calculated. If the curve enclosing the extremal cross section of the Fermi surface in the plane perpendicular to the external magnetic field coincides with the line of nodes of the superconducting order parameter, the effect of the transition to the superconducting state on the amplitude of magnetization oscillations is negligible. If the line of nodes is oriented differently with respect to the applied magnetic field, the de Haas-van Alphen oscillations are suppressed in a manner qualitatively similar to the case of conventional superconductors. Zh. éksp. Teor. Fiz. 113, 2174–2192 (June 1998)     

Oscillator with a centrifugal barrier

We study the wave functions and energy levels of a one-dimensional oscillator with a centrifugal barrier of the form s(s+1)/x². It is shown that a barrier of this kind automatically implies the point potential A(s)(x)/x. It is also shown that two different sets of even states are physically admissible, but that only one of these sets transforms continuously into the set of states of harmonic oscillator when the centrifugal barrier is allowed to vanish and is preferable for this reason.Translated from Izvestiya Vysshkh Uchebnykh Zavedenii, Fizika, No. 5, pp. 35–39, May, 1987.The authors acknowledge useful discussions with B. M. Bolotovskii, B. A. Lysov, and O. A. Khrustalev.     

Recovery of Kraft Lignin from Aqueous Solutions with Oxotitanium Sulfate,Aluminum Sulfate,and Their Mixture

Coagulation recovery of kraft lignin from aqueous solutions with oxotitanium sulfate, aluminum sulfate, and a composite coagulant based on their mixture was studied in a wide range of coagulant concentrations and solution pH values.     

Singular perturbations of discrete spectrum

Even solutions of the Schrödinger equation with retaining potential x² are constructed for singular perturbation potentials |x|^–. It is shown that the perturbation automatically entails an induced point potential, taking account of which the perturbation matrix elements and Rayleigh-Schrödinger series may be constructed when 1 < < 3/2. In the opposite case (3/2 2), although the solutions are analytic with respect to , not even diverging series can be obtained for the energy solutions without solution of the Schrödinger equation. The analogy with quantum field theory is explored.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 58–64, March, 1988.     

NanoFAST: structure-based design of a small fluorogen-activating protein with only 98 amino acids

One of the essential characteristics of any tag used in bioscience and medical applications is its size. The larger the label, the more it may affect the studied object, and the more it may distort its behavior. In this paper, using NMR spectroscopy and X-ray crystallography, we have studied the structure of fluorogen-activating protein FAST both in the apo form and in complex with the fluorogen. We showed that significant change in the protein occurs upon interaction with the ligand. While the protein is completely ordered in the complex, its apo form is characterized by higher mobility and disordering of its N-terminus. We used structural information to design the shortened FAST (which we named nanoFAST) by truncating 26 N-terminal residues. Thus, we created the shortest genetically encoded tag among all known fluorescent and fluorogen-activating proteins, which is composed of only 98 amino acids.

We solved the structure of a fluorogen-activating protein FAST and synthesized the library of potential fluorogens. Using these data, we designed the shortest genetically encoded fluorescent tag among all known.     

Reentrant Superconductivity in UTe2

JETP Letters - The reentrant superconductivity is the peculiar phenomenon observed in paramagnetic metal UTe2 in magnetic field parallel to the hard magnetisation axis. It is difficult to explain...     

Phase transition in liquid 3He in an aerogel at zero temperature

An expansion of the thermodynamic potential in powers of the order parameter of the superfluid phase transition is found for liquid ³He in an aerogel at T=0. The discontinuity in the compressibility (sound velocity), which is the analog of the discontinuity in the specific heat for second-order temperature phase transitions, is calculated. The magnitude of the critical quantum fluctuations (zero-point vibrations) of the order parameter is estimated. Pis’ma Zh. éksp. Teor. Fiz. 66, No. 10, 655–660 (25 November 1997)     

The Chemical Basis of Fungal Bioluminescence

Many species of fungi naturally produce light, a phenomenon known as bioluminescence, however, the fungal substrates used in the chemical reactions that produce light have not been reported. We identified the fungal compound luciferin 3‐hydroxyhispidin, which is biosynthesized by oxidation of the precursor hispidin, a known fungal and plant secondary metabolite. The fungal luciferin does not share structural similarity with the other eight known luciferins. Furthermore, it was shown that 3‐hydroxyhispidin leads to bioluminescence in extracts from four diverse genera of luminous fungi, thus suggesting a common biochemical mechanism for fungal bioluminescence.