Methods for processing ash residues of TPS vanadium containing slurry

Application of vanadium industrial waste complex processing provides the decision of two main tasks: expanding the raw material base for extremely scarce metal and reduction of an environmental impact on nature. Combined and hydrometallurgical methods of vanadium extraction from the ash residues of TPS vanadium sludge have been developed. These methods allow to extract up to 95% of vanadium that contains in waste, and to obtain a vanadium product suitable for using in different areas of industry

Subexponential estimations in Shirshov's height theorem (in English)

In 1993 E. I. Zelmanov asked the following question in Dniester Notebook: "Suppose that F_{2, m} is a 2-generated associative ring with the identity x^m=0. Is it true, that the nilpotency degree of F_{2, m} has exponential growth?" We show that the nilpotency degree of l-generated associative algebra with the identity x^d=0 is smaller than Psi(d,d,l), where Psi(n,d,l)=2^{18} l (nd)^{3 log_3 (nd)+13}d^2. We give the definitive answer to E. I. Zelmanov by this result. It is the consequence of one fact, which is based on combinatorics of words. Let l, n and d>n be positive integers. Then all the words over alphabet of cardinality l which length is greater than Psi(n,d,l) are either n-divided or contain d-th power of subword, where a word W is n-divided, if it can be represented in the following form W=W_0 W_1...W_n such that W_1 >' W_2>'...>'W_n. The symbol >' means lexicographical order here. A. I. Shirshov proved that the set of non n-divided words over alphabet of cardinality l has bounded height h over the set Y consisting of all the words of degree <n. Original Shirshov's estimation was just recursive, in 1982 double exponent was obtained by A.G.Kolotov and in 1993 A.Ya.Belov obtained exponential estimation. We show, that h<Phi(n,l), where Phi(n,l) = 2^{87} n^{12 log_3 n + 48} l. Our proof uses Latyshev idea of Dilworth theorem application.Comment: 21 pages, Russian version of the article is located at the link arXiv:1101.4909; Sbornik: Mathematics, 203:4 (2012), 534 -- 55

ОЦЕНКИ, СВЯЗАННЫЕ С ТЕОРЕМОЙ ШИРШОВА О ВЫСОТЕ

The paper is devoted to subexponential estimations in Shirshov’s Height theorem. A word W is n-divisible, if it can be represented in the following form: W = W0W1 · · · Wn such that W1 ≺ W2 ≺ · · · ≺ Wn. If an affine algebra A satisfies polynomial identity of degree n then A is spanned by non n-divisible words of generators a1 ≺ · · · ≺ al . A. I. Shirshov proved that the set of non n-divisible words over alphabet of cardinality l has bounded height h over the set Y consisting of all the words of degree 6 n−1. We show, that h &lt; Φ(n, l), where Φ(n, l) = 296l · n 12 log3 n+36 log3 log3 n+91 . Let l, n и d &gt; n be positive integers. Then all the words over alphabet of cardinality l which length is greater than Ψ(n, d, l) are either n-divisible or contain d-th power of subword, where Ψ(n, d, l) = 227l(nd) 3 log3 (nd)+9 log3 log3 (nd)+36 . In 1993 E. I. Zelmanov asked the following question in Dniester Notebook: “Suppose that F2,m is a 2-generated associative ring with the identity x m = 0. Is it true, that the nilpotency degree of F2,m has exponential growth?” We give the definitive answer to E. I. Zelmanov by this result. We show that the nilpotency degree of l-generated associative algebra with the identity x d = 0 is smaller than Ψ(d, d, l). This imply subexponential estimations on the nilpotency index of nil-algebras of an arbitrary characteristics. Original Shirshov’s estimation was just recursive, in 1982 double exponent was obtained, an exponential estimation was obtained in 1992.Our proof uses Latyshev idea of Dilworth theorem application. We think that Shirshov’s height theorem is deeply connected to problems of modern combinatorics. In particular this theorem is related to the Ramsey theory. We obtain lower and upper estimates of the number of periods of length 2, 3,(n−1) in some non n-divisible word. These estimates are differ only by a constant Работа посвящена получению оценок в теореме Ширшова о высоте. Слово W называется n-разбиваемым, если его можно представить в виде W = W0W1 · · · Wn где подслова W1, . . . , Wn идут в порядке лексикогра- фического убывания. Из не n-разбиваемых слов состоит базис алгебры с тождеством степени n. А. И. Ширшов показал, что множество слов, не яв- ляющихся n-разбиваемыми, над алфавитом из l букв имеет ограниченную высоту h над Y – множеством слов степени не выше n−1. Мы показываем, что h &lt; Φ(n, l), где Φ(n, l) = 296l · n 12 log3 n+36 log3 log3 n+91 . Пусть l, n и d &gt; n – некоторые натуральные числа. Тогда все слова над l-буквенном алфавитом длины больше, чем Ψ(n, d, l), либо содержат x d , либо являются n-разбиваемыми, где Ψ(n, d, l) = 227l(nd) 3 log3 (nd)+9 log3 log3 (nd)+36 . В 1993 году Е. И. Зельманов поставил следующий вопрос в Днестров- ской тетради: “Пусть F2,m – свободное 2-порожденное ассоциативное кольцо с тож- деством x m = 0. Верно ли, что класс нильпотентности кольца F2,m растет экспоненциально по m?” В работе показано, что в l-порожд¨енной ассоциативной алгебре с тождеством x d = 0 класс нильпотентности меньше, чем Ψ(d, d, l). Тем самым получаются субэкспоненциальные оценки на индекс нильпотентно- сти ниль-алгебр для произвольной характеристики. Изначальная оценка высоты у Ширшова носила рекурсивный характер, в 1982 году была получена двойная экспонента, в 1992 году – экспо- ненциальная оценка. Доказательство использует идею В. Н. Латышева, связанную с приме- нением теоремы Дилуорса к исследованию не n-разбиваемых слов. Нам представляется, что теорема о высоте имеет глубокую связь с задачами современной комбинаторики, в частности, Рамсеевского типа. С помощью такого рода соображений получаются верхние и нижние оценки количества периодов длины 2, 3,(n−1) в не n-разбиваемом слове, отличающиеся только постоянным множителем.

Coulomb interaction and magnetic catalysis in the quantum Hall effect in graphene

The dynamics of symmetry breaking responsible for lifting the degeneracy of the Landau levels in the integer quantum Hall effect in graphene is studied in a low-energy model with the Coulomb interaction. The gap equation for Dirac quasiparticles is analyzed for both the lowest and higher Landau levels, taking into account the Landau levels mixing. It is shown that the characteristic feature of the long-range Coulomb interaction is the decrease of the gap parameters with increasing the Landau level index $n$ ("running" gaps). The renormalization (running) of the Fermi velocity as a function of $n$ is also studied. The solutions of the gap equation reproduce correctly the experimentally observed integer quantum Hall plateaus in graphene in strong magnetic fields.Comment: 22 pages, 5 figures; Final version published in the Proceedings of the 2010 Nobel Symposium on Graphene and Quantum Matte

Oscillations of Induced Magnetization in Superconductor-Ferromagnet Heterostructures

We study a change in the spin magnetization of a superconductor-ferromagnet (SF) heterostructure, when temperature is lowered below the superconducting transition temperature. It is assumed that the SF interface is smooth on the atomic scale and the mean free path is not too short. Solving the Eilenberger equation we show that the spin magnetic moment induced in the superconductor is an oscillating sign-changing function of the product $hd$ of the exchange field $h$ and the thickness $d$ of the ferromagnet. Therefore the total spin magnetic moment of the system in the superconducting state can be not only smaller (screening) but also greater (anti-screening) than that in the normal state, in contrast with the case of highly disordered (diffusive) systems, where only screening is possible. This surprising effect is due to peculiar periodic properties of localized Andreev states in the system. It is most pronounced in systems with ideal ballistic transport (no bulk disorder in the samples, smooth ideally transparent interface), however these ideal conditions are not crucial for the very existence of the effect. We show that oscillations exist (although suppressed) even for arbitrary low interface transparency and in the presence of bulk disorder, provided that $h \tau \gg 1$ ($\tau$ -- mean free path). At low interface transparency we solve the problem for arbitrary strength of disorder and obtain oscillating magnetization in ballistic regime ($h \tau \gg 1$) and nonoscillating magnetization in diffusive one ($h \tau \ll 1$) as limiting cases of one formula.Comment: 10 pages, 2 figures, accepted for publication in Phys. Rev.

Adsorption and two-body recombination of atomic hydrogen on 3^3He-4^4He mixture films

We present the first systematic measurement of the binding energy $E_a$ of hydrogen atoms to the surface of saturated $^3$He-$^4$He mixture films. $E_a$ is found to decrease almost linearly from 1.14(1) K down to 0.39(1) K, when the population of the ground surface state of $^3$He grows from zero to $6\times10^{14}$ cm$^{-2}$, yielding the value $1.2(1)\times 10^{-15}$ K cm$^2$ for the mean-field parameter of H-$^3$He interaction in 2D. The experiments were carried out with overall $^3$He concentrations ranging from 0.1 ppm to 5 % as well as with commercial and isotopically purified $^4$He at temperatures 70...400 mK. Measuring by ESR the rate constants $K_{aa}$ and $K_{ab}$ for second-order recombination of hydrogen atoms in hyperfine states $a$ and $b$ we find the ratio $K_{ab}/K_{aa}$ to be independent of the $^3$He content and to grow with temperature.Comment: 4 pages, 4 figures, all zipped in a sigle file. Submitted to Phys. Rev. Let

Bose-Einstein condensation of quasiparticles in graphene

The collective properties of different quasiparticles in various graphene based structures in high magnetic field have been studied. We predict Bose-Einstein condensation (BEC) and superfluidity of 2D spatially indirect magnetoexcitons in two-layer graphene. The superfluid density and the temperature of the Kosterlitz-Thouless phase transition are shown to be increasing functions of the excitonic density but decreasing functions of magnetic field and the interlayer separation. The instability of the ground state of the interacting 2D indirect magnetoexcitons in a slab of superlattice with alternating electron and hole graphene layers (GLs) is established. The stable system of indirect 2D magnetobiexcitons, consisting of pair of indirect excitons with opposite dipole moments, is considered in graphene superlattice. The superfluid density and the temperature of the Kosterlitz-Thouless phase transition for magnetobiexcitons in graphene superlattice are obtained. Besides, the BEC of excitonic polaritons in GL embedded in a semiconductor microcavity in high magnetic field is predicted. While superfluid phase in this magnetoexciton polariton system is absent due to vanishing of magnetoexciton-magnetoexciton interaction in a single layer in the limit of high magnetic field, the critical temperature of BEC formation is calculated. The essential property of magnetoexcitonic systems based on graphene (in contrast, e.g., to a quantum well) is stronger influence of magnetic field and weaker influence of disorder. Observation of the BEC and superfluidity of 2D quasiparticles in graphene in high magnetic field would be interesting confirmation of the phenomena we have described.Comment: 13 pages, 5 figure