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Introduction La fistule gastrique (FG) represente une des complications les plus graves apres sleeve gastrectomy (LSG), pouvant conduire dans certains cas au deces du patient. Leur prise en charge est complexe et souvent longue. Nous rapportons notre experience de la prise en charge multidisciplinaire de FG apres LSG. Patients et Methodes Entre novembre 2004 et Juillet 2008, 180 patients ont ete operes d’une SG pour obesite morbide (Indice de masse corporelle, IMC > 40 ou > 35 avec comorbidites) au CHU d’Amiens. Un TOGD postoperatoire etait systematiquement effectue a J1. Sept (3,8 %) patients ont eu une FG postoperatoire. Quatre patients ont ete transferes pour prise en charge de la FG. Nous avons analyse les caracteristiques demographiques, les modalites du traitement endoscopique, radiologique et chirurgical ainsi que le retentissement de la FG sur la perte d’exces de poids. Resultats Il y avait 2 hommes et 9 femmes avec un âge median de 38 ± 10 ans avec un IMC initial de 46 (IMC > 50, n = 3). Le diagnostic de FG etait pose soit precocement (J1) par le TOGD (45 %) soit plus tardivement (J5) par un scanner opacifie (55 %) effectue pour un tableau de sepsis severe. Le delai median d’apparition de la FG etait de 3 jours (1-12). Parmi les 11 patients, un patient est decede immediatement apres la decouverte de la FG d’une embolie pulmonaire. Parmi les 10 autres patients, un seul a pu etre traite sans reintervention. Tous les patients etaient traites par antibiotherapie, IPP, sandostatine et nutrition parenterale. Dans 90 % des cas, une reintervention etait necessaire pour lavage, drainage de la FG (intubation par sonde de Pezzer n = 7) et jejunostomie d’alimentation (n = 5). Parmi les patients reoperes, le drainage chirurgical seul a permis le tarissement de la FG chez 2 (22 %) patients. Pour les autres, un drainage percutane (n = 5), un encollage a l’histoacryl (n = 4) et la mise en place d’un stent metallique couvert (n = 6) ont permis de tarir la FG chez 5 (71,4 %) patients. Pour 2 patients, une re-intervention tardive comportant une gastrectomie totale (n = 1) ou une anse montee sur la FG (n = 1) ont permis de tarir la FG. La duree d’hospitalisation mediane etait de 50 ± 34 jours. Malgre la FG, la perte moyenne d’exces de poids etait de 57 % apres 12 mois de suivi. Conclusion Le traitement conservateur des FG apres LSG necessite une prise en charge multidisciplinaire, complexe et longue. Cependant, cette strategie permet d’obtenir un tarissement de la FG dans 71 % des cas sans alterer les resultats de la chirurgie initiale.

Specific electronic features have been found in structures consisting of metal oxide layers on silicon substrates upon swift heavy ion irradiation. These features are linked to the appearance of radiation-induced negative differential resistances in the structures. In the reversed bias direction they show high frequency current pulsations at around ∼10kHz frequency. Their amplitude increases with increasing applied voltage. The pulsation frequency also shows a small increase. The current amplitude depends on the ion fluence and flux.

Ab initio calculations of the BST heterostructure with equiatomic constituent of Sr and Ba species has been carried out within hybrid functional B3PW involving a hybrid of non-local Fock exchange and Becke's gradient corrected exchange functional combined with the non-local gradient corrected correlation potential by Perdew and Wang. The suggested scheme of calculations reproduces experimental lattice parameters of both pure BaTiO3 and SrTiO3. The calculated optical band gap for the pure SrTiO3 (BaTiO3) is 3.56 (3.46) eV (expt. 3.25 and 3.20 eV, respectively), i.e. agreement is much better than in the standard LDA or HF calculations. In the Ba0.5Sr0.5TiO3 solid solution the gap is reduced by 0.2 eV. The BST upper valence band consists of O 2p atomic orbitals (AO) with a small admixture of Ti 3d, whereas the conduction band bottom consists mostly of Ti 3d orbitals with a small contribution of O orbitals. The Sr (Ba) atomic orbitals make a significant contribution to the higher part of the conduction band. The electron density maps demonstrate the covalency effects in the Ti-O bonding. The electron density near the Sr atoms is stronger localized, as compared with the Ba ions.

The Fourier transforms of covalent charge density and the contribution of the third and fourth order of perturbation series for the energy (E) of alkali and some transition metals are calculated on the basis of self-consistent Brillouin-Wigner pseudopotential perturbation theory. The scattering of electrons on the planes of the first and second Brillouin zones in the b.c.c. lattice is taken into account. It is shown that the value E is of the same order as the heat of polymorphic transition. The convergence of perturbation series in pseudopotential theory for the calculation of transition metal energy with Animalu's form-factors is investigated. [Russian Text Ignored].

The energy of disordered solid interstitial solutions and the energy of mixing in these solutions up to the second order of perturbation theory in pseudopotential is discussed. The correspondence of items, defining the band structure energy in interstitial and substitutional solutions is established. A comparative analysis of the contributions to the total energy of boron and carbon solutions in aluminium is performed. Numerical calculations show that the increase of impurity concentration results in the relaxation of elastic stresses, which is indicated by the decrease of quasielastic Fourier-transform forces. The applicability of the perturbation theory in pseudopotentials limited to second-order terms in the calculations of the energy of mixing in dilute interstitial solutions is analyzed. The alloying effect on the positive energy of mixing is discussed. [Russian Text Ignored]

We fit the Animalu model potential by using the crystal equation of state. We give the fitted parameters for 25 metals that have a cubic lattice. We calculate the concentrational dependence of the lattice parameters for the alloys Al-Cu and Al-Ag. The derivative da/dc in these alloys agrees well with the experimental data.

The Brillouin-Wigner pseudopotential perturbation theory is used for calculating multi-ion interaction effects contributing to the mixing energy and the total bond energy of phases with Ll2 structure. It is shown that these contributions are of the same order as the mixing energy itself and they must be taken into account in theoretical investigations of the order–disorder phase transition temperature. Numerical results for some alloys with Ll2 structure are presented and the phase transition temperatures for Cu3Au and Au3Cu are discussed.

The pseudopotential method is used to calculate first- and second-order interaction parameters in f.c.c. and h.c.p. interstitial solutions of aluminium and magnesium alloys. Values calculated of interaction parameters are used for an estimation of the series convergence for the logarithm of the boron and carbon activity coefficient. The results show that the series convergence depends, to a great extent, on the selection of the alloying element and its concentration. [Russian Text Ignored].

Isotherms have been constructed and compressibilities and sound velocities have been calculated for the hydrides of alkaline metals on the basis of the functional theory of the local electron density, within the framework of the pseudopotential method. The expression obtained for the electron density distribution allows one to perform the analysis of the character of the binding forces and to determine the dependence of the degree of ionization on pressure in these compounds.

A general theory given in a previous paper which allows to determine theoretically the structures of ordered phases in binary alloys with complex lattice is used for an investigation of the system MgCd. The equilibrium value of the lattice parameter a in the disordered solution is calculated as a function of concentration. For a definite model potential the energetically favoured superstructures are obtained and compared with those observed experimentally. [Russian Text Ignored]

Now in recent years considerable progress has been made in the calculation of phase diagrams by a method based on modern concepts of the quantum theory of metals and alloys [3-5]. In this method thermodynamic functions are expressed in terms of microscopical characteristics of electron-ion interaction in metallic systems. This approach makes it possible to classify alloys according to the intersolubility of their components and discover the conditions for the existence and the causes of formation of intermediate phases in binary alloys [4, 5]. Initially, this method was employed for the examination of alloys based on nontransition metals. In a more recent work [6], however, electron-ion interaction parameters are given for transition metals. As a result, the possibility has been opened up of calculating the thermodynamic properties of transition metal alloys. In view of the extensive use of alloys of the Ni -A1 system as coatings based on intermetallic compounds, matrices of composite materials, and strengthening-phase matrices of heat-resisting alloys, the present work was undertaken with the aim of determining, by the pseudopotential method, the energy of a disordered nickelbase solid solution and of calculating possible intermediate phases. It was considered of particular interest that in an experimental phase diagram there exists a NiA1 (B2) phase having a bcc lattice, whereas the pure components of the alloy - nickel and aluminum - have fcc lattices. The authors were unable to find a theoretical explanation, supported by calculation, of this phenomenon in the literature. Disordered Solid Solutions To understand the nature of phase equilibria in alloys, it is extremely important to know the character of the electron-ion interaction occurring in them. In this connection, numerous thoeries of phases in alloys utilize fairly crude hypotheses. Of the various theories explaining the contribution from the conduction electrons to the full bond energy, the best-known is the Brillouin zone effect theory proposed by Jones and Goodenough. With the aid of this theory it has proved possible, inter alia, satisfactorily to explain the HumeRothery rule concerning the influence exerted by the effective charge carried by an ion in an alloy on a phase equilibrium. Nevertheless, in the employment of this theory for the explanation of phase diagrams certain difficulties arise. Jones' theory is based on a coarse zonal model neglecting all properties of the atoms corn

The authors review their work on the use of the pseudopotential method in the thermodynamics of alloys. Treatment of the theory of phase equilibria in alloys on the basis of the pseudopotential method makes it possible to use first principles in order to set up a thermodynamics of alloys in which the energy parameters are not presumed to be phenomenological but are calculated from the electronic characteristics of the pure components. The approach developed allows a priori calculation of the phase diagrams of alloys, the effect of cubic compression on phase diagrams, and the various thermodynamic functions of alloys. A classification of phases in alloys on the basis of analysis of their thermodynamic characteristics is proposed.

For the investigation of the free energy of metals and their temperature dependence in solid and liquid phases the pseudopotential method is used. In calculating the free energy in a solid phase the lattice vibration contribution is considered. In definition of the pair potential in liquid metals the volume change of the metal during its melting is taken into account. The structure of liquid metals is calculated with the help of the found potential using the integral equation method. The solutions of different equations for the radial distribution function are compared and the influence of the model form factor and the method of screening in the electron gas on the liquid metal structure is discussed.

It is shown that the structures of the ordered phases in binary alloys with complex Ising lattice (made up by the α-Bravais lattices displaced with respect to each other) can be determined theoretically by means of the static concentration wave (s.c.w.) method and pseudopotential theory. The expression which gives the relationship between the phenomenological parameters of the s.c.w. method and the energy-wavenumber characteristicof thepseudopotential theory is obtained. The superstructures which may be stable with respect to the formation of an antiphase boundary structure is obtained for the hexagonal close-packed lattice. [Russian Text Ignored].

A pseudopotential method is applied to construct the thermodynamical potential of a binary solid solution. The state equation is solved for a disordered solid solution. The mixing energy is shown to be a complex concentration function depending on the type of the crystalline lattice. The influence of a uniform compression on the solubility of alloy components is investigated, the enthalpy and work function under adiabatic compression are determined. The numerical calculations are carried out for MgZn and BaCd systems. [Russian Text Ignored].

The calculation of the interatomic interaction by the pseudopotential method with different models for the form factors has been considered, and the effect of the kind of screening of the electron gas on the form of the potential has been investigated. The potentials of the pair interaction which were calculated have been used to solve the Bogolyubov-Born-Green and the Percus-Yevick integral equations for the radial distribution function. Questions about the applicability of this method for computing the structure and thermodynamic properties of liquid metals are discussed.

Pseudopotential formalism was used to describe the phase transition from a two-phase to a one-phase state in alloys with limited solubility. The combined use of the pseudopotential and static concentration wave methods for calculating the temperature of the order-disorder phase transition was generalized to the case of lattices with a basis. Numerical calculations were carried out for the limiting solubility curves in the system Cd-Zn and the order-disorder transition temperatures for Mg3Cd, MgCd, and MgCd3 superstructures.

The energy and deformation interaction in disordered interstitial solutions are determined by means of the pseudopotential method. Calculations are made for the systems Ti-C and Zr-C. Comparison of the deformation interaction energies and the Fourier transforms of the quasielastic forces has shown that in the system Ti-C the deformation interaction is greater than in Zr-C. Numerical calculations have established that filling of the z sublattice of octahedral interstices is energetically more advantageous in the bcc interstitial solution Zr-C.

The elastic and thermal properties of alkali metals are analyzed from the viewpoint of effective ion-ion interaction in rectilinear space. Consideration is given to the approximation of pair interaction between ions. The atomic-interaction potential is calculated on the basis of the pseudopotential method. Numerical calculations are made of the elastic constants, the second and fourth moments of the frequency spectrum, the temperature dependence of the Debye temperature, the specific heat, and the vibrational free energy of Na, K, Rb, and Cs. The calculations are in good agreement with the experimental values. The influence of exchange-correlation effects on the given properties is discussed. The results obtained indicate that the pseudopotential method may be successfully used for the calculation of the thermodynamic properties of metals by a traditional scheme, restricting consideration to the first two coordination spheres.

First principles slab simulations of copper 2D superlattices of different densities on the perfect MgO(001) surface are performed using the DFT method as implemented into the CRYSTAL98 computer code. In order to clarify the nature of interfacial bonding, we consider regular 1/4, 1/2 and 1 monolayer (ML) coverages and compare results of our calculations with various experimental and theoretical data. Our general conclusion is that the physical adhesion associated with a Cu polarization and charge redistribution gives the predominant contribution to the bonding of the regular Cu 2D layer on the MgO(001) surface.

The effect of electron correlation corrections in the novel theory predicting the growth mode of a thin metallic film on an insulating substrate has been studied. We discuss the influence of the substrate slab thickness on the energies of formation for several two-dimensional phases, which, in principle, may form in Ag layer on (0 0 1) MgO substrate. We analyze also the sensitivity of the key energy parameter––Fourier transform of the mixing potential V (0) to the choice of correlation functionals.

The free energies of aluminum in the solid and liquid phases are calculated. The free energy in the solid state is determined in the quasiharmonic approximation. The radial distribution function of liquid aluminum is found by solving the Bogolyubov-Born-Green equation. The convergence of the series for finding the electrostatic energy of the liquid metal is discussed. The value obtained for the melting point agrees well with the experimental value.

A study is made of the influence of alloying on the solubility of boron fibers in the composite material Mg-B. Three models of solutions are considered on the assumption that the boron atoms either occupy interstices or replace the matrix atoms. A calculation is made of the parameters of the interaction between the fiber material with the magnesium matrix and with alloying elements of different valence. A correlation is established between the valence of an alloying element and its influence on the solubility of a fiber in the matrix. Silicon and aluminum have positive parameters of the interaction with the boron atoms and prevent dissolution of the fibers in the matrix.

The pseudopotential method is used to determine the Gruneisen constant and the temperature dependence of the elastic constants for T > θ in alkali metals. An analysis is made of the influence of exchange-correlational effects in the electronic gas on the quantities mentioned above. The calculated values are in good agreement with experimental data in Na, K, Rb, and Cs. The results of the paper indicate that the considered anharmonic characteristics of alkali metals are determined primarily by the interaction in the first two coordination spheres.

The thermodynamic properties (TP) of atom-vacancy solid solutions are investigated with molecular-dynamics calculations using N-body potentials. For the example of copper we analyze the vacancy concentration dependence of TP in the high-pressure simulations. Calculated pressure-induced TP of atom-vacancy solid solutions in copper prove the necessity of accounting the peculiarities of the crystal structure and potential in the study of vacancy-driven properties of solids. \textcopyright{} 1996 The American Physical Society.