Surgical Correction of Child Planovalgus Deformity by Porous TiNi-based Implants

The question of child degenerative-dystrophic diseases is predominate in orthopedic pathology, where the problem of its treatment is very acute. Excluding the modern treatment methods, the number of children suffering planovalgus deformity is comparably more to total orthopedic patients. This article describes a surgical treatment method of child planovalgus deformity by applying porous biocomposite materials from TiNi alloy. The method involves inserting porous frustoconical composite TiNi implant into subtalar joint, which, in its turn, could correct the deformation and shape the arch of foot eliminating planovalgus deformity

Deep Oxidation of Fluorinated Hydrocarbons in Molten Catalysts

The oxidation of fluorine-containing organic substances: fluorocarbon liquid M-1, fluorinated alcohol H(CF2)8CH2OH, and powder polytetrafluoroethylene with air has been studied in melts: NaOH; 43 mol.% LiCl В - 33 mol.% NaCl - 24 mol.% KCl (eutectic mixture); (LiCl-NaCl-KCl)eutec. + 10 mass.% V2O5; (LiCl-NaCl-KCl) eutec. + 15 mass.% V2O5; 56 mol.% Na2CO3 - 44 mol.% K2CO3 (eutectic), (Na2CO3 K2CO3)eutect. + 15 mass.% V2O5, and K3V5O14. The compositions of the melts have been examined by GC, DTA, chemical analysis and XRD, and they have been shown to change during the reaction, depending on the composition and partial pressure of the gaseous products over the melt surface. The alkali metal chloride melt containing 15 mass.% V2O5 has been found to be most stable to the action of fluorine compounds. Possibility of deep oxidation of fluorine-containing organic substances in melts based on hydroxides, carbonates and chlorides of alkali metals doped with oxides of vanadium has been proved. The process of deep oxidation of fluorinated hydrocarbons is accompanied by formation of an equilibrium mixture containing hydroxides, carbonates, chlorides and fluorides of alkali metals, as well as their vanadates, if V2O5 additive is used. The relative amounts of these substances in molten systems are determined by the partial pressure of oxygen, CO2 and water vapor

Bound Chains of Tilted Dipoles in Layered Systems

Ultracold polar molecules in multilayered systems have been experimentally realized very recently. While experiments study these systems almost exclusively through their chemical reactivity, the outlook for creating and manipulating exotic few- and many-body physics in dipolar systems is fascinating. Here we concentrate on few-body states in a multilayered setup. We exploit the geometry of the interlayer potential to calculate the two- and three-body chains with one molecule in each layer. The focus is on dipoles that are aligned at some angle with respect to the layer planes by means of an external eletric field. The binding energy and the spatial structure of the bound states are studied in several different ways using analytical approaches. The results are compared to stochastic variational calculations and very good agreement is found. We conclude that approximations based on harmonic oscillator potentials are accurate even for tilted dipoles when the geometry of the potential landscape is taken into account.Comment: 10 pages, 6 figures. Submitted to Few-body Systems special issue on Critical Stability, revised versio

Density Waves in Layered Systems with Fermionic Polar Molecules

A layered system of two-dimensional planes containing fermionic polar molecules can potentially realize a number of exotic quantum many-body states. Among the predictions, are density-wave instabilities driven by the anisotropic part of the dipole-dipole interaction in a single layer. However, in typical multilayer setups it is reasonable to expect that the onset and properties of a density-wave are modified by adjacent layers. Here we show that this is indeed the case. For multiple layers the critical strength for the density-wave instability decreases with the number of layers. The effect depends on density and is more pronounced in the low density regime. The lowest solution of the instability corresponds to the density waves in the different layers being in-phase, whereas higher solutions have one or several adjancet layers that are out of phase. The parameter regime needed to explore this instability is within reach of current experiments.Comment: 7 pages, 4 figures. Final version in EPJD, EuroQUAM special issue "Cold Quantum Matter - Achievements and Prospects

Dimers, Effective Interactions, and Pauli Blocking Effects in a Bilayer of Cold Fermionic Polar Molecules

We consider a bilayer setup with two parallel planes of cold fermionic polar molecules when the dipole moments are oriented perpendicular to the planes. The binding energy of two-body states with one polar molecule in each layer is determined and compared to various analytic approximation schemes in both coordinate- and momentum-space. The effective interaction of two bound dimers is obtained by integrating out the internal dimer bound state wave function and its robustness under analytical approximations is studied. Furthermore, we consider the effect of the background of other fermions on the dimer state through Pauli blocking, and discuss implications for the zero-temperature many-body phase diagram of this experimentally realizable system.Comment: 18 pages, 10 figures, accepted versio

Near Ambient Pressure XPS and MS Study of CO Oxidation over Model Pd Au HOPG Catalysts The Effect of the Metal Ratio

In this study, the dependence of the catalytic activity of highly oriented pyrolytic graphite HOPG supported bimetallic Pd Au catalysts towards the CO oxidation based on the Pd Au atomic ratio was investigated. The activities of two model catalysts differing from each other in the initial Pd Au atomic ratios appeared as distinctly different in terms of their ignition temperatures. More specifically, the PdAu 2 sample with a lower Pd Au surface ratio 0.75 was already active at temperatures less than 150 C, while the PdAu 1 sample with a higher Pd Au surface ratio 1.0 became active only at temperatures above 200 C. NAP XPS revealed that the exposure of the catalysts to a reaction mixture at RT induces the palladium surface segregation accompanied by an enrichment of the near surface regions of the two component Pd Au alloy nanoparticles with Pd due to adsorption of CO on palladium atoms. The segregation extent depends on the initial Pd Au surface ratio. The difference in activity between these two catalysts is determined by the presence or higher concentration of specific active Pd sites on the surface of bimetallic particles, i.e., by the ensemble effect. Upon cooling the sample down to room temperature, the reverse redistribution of the atomic composition within near surface regions occurs, which switches the catalyst back into inactive state. This observation strongly suggests that the optimum active sites emerge under reaction conditions exclusively, involving both high temperature and a reactive atmospher

Thermodynamics of Dipolar Chain Systems

The thermodynamics of a quantum system of layers containing perpendicularly oriented dipolar molecules is studied within an oscillator approximation for both bosonic and fermionic species. The system is assumed to be built from chains with one molecule in each layer. We consider the effects of the intralayer repulsion and quantum statistical requirements in systems with more than one chain. Specifically, we consider the case of two chains and solve the problem analytically within the harmonic Hamiltonian approach which is accurate for large dipole moments. The case of three chains is calculated numerically. Our findings indicate that thermodynamic observables, such as the heat capacity, can be used to probe the signatures of the intralayer interaction between chains. This should be relevant for near future experiments on polar molecules with strong dipole moments.Comment: 15 pages, 5 figures, final versio

Layers of Cold Dipolar Molecules in the Harmonic Approximation

We consider the N-body problem in a layered geometry containing cold polar molecules with dipole moments that are polarized perpendicular to the layers. A harmonic approximation is used to simplify the hamiltonian and bound state properties of the two-body inter-layer dipolar potential are used to adjust this effective interaction. To model the intra-layer repulsion of the polar molecules, we introduce a repulsive inter-molecule potential that can be parametrically varied. Single chains containing one molecule in each layer, as well as multi-chain structures in many layers are discussed and their energies and radii determined. We extract the normal modes of the various systems as measures of their volatility and eventually of instability, and compare our findings to the excitations in crystals. We find modes that can be classified as either chains vibrating in phase or as layers vibrating against each other. The former correspond to acoustic and the latter to optical phonons. Instabilities can occur for large intra-layer repulsion and produce diverging amplitudes of molecules in the outer layers. Lastly, we consider experimentally relevant regimes to observe the structures.Comment: 17 pages, 20 figures, accepted versio