Theoretical evaluation of zirconia and hafnia as gate oxides for si microelectronics

Parameters determining the performance of the crystalline oxides zirconia (ZrO2) and hafnia (HfO2) as gate insulators in nanometric Si electronics are estimated via ab initio calculations of the energetics, dielectric properties, and band alignment of bulk and thin-film oxides on Si (001). With their large dielectric constants, stable and low-formation-energy interfaces, large valence offsets, and reasonable (though not optimal) conduction offsets (electron injection barriers), zirconia and hafnia appear to have considerable potential as gate oxides for Si electronics.     

Peroxynitrite decomposition catalyst prevents apoptotic cell death in a human astrocytoma cell line incubated with supernatants of HIV-infected macrophages

Background  

Oxidative stress has shown to contribute in the mechanisms underlying apoptotic cell death occuring in AIDS-dementia complex. Here we investigated the role of peroxynitrite in apoptosis occurring in astroglial cells incubated with supernatants of HIV-infected human primary macrophages (M/M).     

Computing automorphisms of abelian number fields

Let be an abelian number field of degree . Most algorithms for computing the lattice of subfields of require the computation of all the conjugates of . This is usually achieved by factoring the minimal polynomial of over . In practice, the existing algorithms for factoring polynomials over algebraic number fields can handle only problems of moderate size. In this paper we describe a fast probabilistic algorithm for computing the conjugates of , which is based on -adic techniques. Given and a rational prime which does not divide the discriminant of , the algorithm computes the Frobenius automorphism of in time polynomial in the size of and in the size of . By repeatedly applying the algorithm to randomly chosen primes it is possible to compute all the conjugates of .

     

Generation of analytic semigroups in theL p topology by elliptic operators inR n

Strongly elliptic differential operators with (possibly) unbounded lower order coefficients are shown to generate analytic semigroups of linear operators onL ^p(R ⁿ ), 1≦p≦∞. An explicit characterization of the domain is given for 1<p<∞. An application to parabolic problems is also included. This work has been partially supported by the Research Funds of the Ministero della Pubblica Istruzione. The authors are members of GNAFA (Consiglio Nazionale delle Ricerche).     

Numerical simulation of free-surface thermally influenced flows for nonhomogeneous fluids

A finite-difference technique is presented to simulate the behavior of natural water bodies under the influence of pollutants and temperature differences. The mathematical model, which has been discretized, is the closed system obtained by combining the Navier-Stokes equations, the heat transfer equation, the diffusion equations, and an equation relating the fluid density to both the chemical concentration and the temperature. The numerical method is based on the marker-and-cell method, which has been extended to consider the volume expansion due to heat transfer and the density variations.     

The state of 57Fe in pure and oxidized tin chalcogenides by Mössbauer spectroscopy

A Mössbauer spectroscopy study has been made of the stabilization states of ⁵⁷Fe in pure tin chalcogenides. The values of the isomer shifts and the quadrupole splittings lead to the conclusion that iron presents the electronic configuration 3d⁵4s^x at high spin in the interstitial position. This result is confirmed varying the ⁵⁷Fe neighbours by partial substitution of tellurium with oxygen. In this case, too, the values of Mössbauer parameters confirm the same results. The quadrupole moment present in pure SnTe doped ⁵⁷Co, and the shift of isomer shift towards less positive values for the oxidizated samples have been qualitatively justified as well.     

Carbon-13 NMR characterisation of carboxyl derivatives of 1-ureidopyrroles

1-Ureido-5-methyl-2,3-dicarbethoxypyrrole under acidic conditions afforded different partially hydrolyzed or decarboxylated products. It has been possible to characterize two isomeric monoethyl esters of dicarboxylic acids of 1-ureidopyrroles by proton gated decoupled carbon-13 nmr spectra on the basis of multiplicities of the carbonyl carbons resonances.     

Oxidation of tertiary polycycl1c amines by RuO4

The reactions of certain tertiary polycyclic amines such as N-benzyl-9-azabicy-clo- [3,3,1]-nonane, N-benzyl-5, 6-dihydro-11H-dibenz [b,e] azepine, and N-benzyl-1,2,3,4-tetrahydroisoquinoline with ruthenium tetroxide, taking place in both heterogeneous and homogeneous systems, have made it possible to establish the order of reactivity of the various methylene groups adjacent to the nitrogen with respect to this oxidizing agent.