Calculation of the phase diagram of the TiZr alloy and investigation of the tendency toward separation of the ω phase

The electronic, structural, and thermodynamic properties of the TiZr equiatomic alloy have been calculated in terms of the electron density functional theory and Debye-Grüneisen model. The calculated lattice parameters a and c/a agree well with experimental data for the α, ω, and β phases. It has been shown that the ω phase is stable at atmospheric pressure and low temperatures, and it remains energetically more favorable up to T = 600 K. In the temperature range 600 K < T < 900 K, the α phase becomes stable, and above 900 K, the β phase of the TiZr alloy is stable. The phase diagram constructed in this study agrees qualitatively with the available experimental data. A tendency toward separation of the TiZr equiatomic alloy in the ω phase has been analyzed. It has been demonstrated that, in the ground state, the TiZr equiatomic alloy in the ω phase exhibits a tendency toward ordering rather than toward phase separation.     

Measurement of the strong-interaction shift and broadening of the ground state of the pp̄ atom

The K_α X-rays from pp̄ atoms formed in H₂ gas at normal temperature and pressure are unambiguously identified by coincidences with L X-rays populating the 2P level. Background due to inner bremsstrahlung is suppressed by selecting events annihilating into neutral final states only. The K_α line is observed with a significance of more than 25 standard deviations at an energy of 8.67 (15) keV. From fits to the K_α line we obtain a strong-interaction shift and width of the 1S level, averaged over the unresolved spin singlet and triplet contributions, of ΔE + iΓ/2 = [−0.70(15) + i0.80(20)] keV.     

Vibrations of Au?? and FeAu?? nanoparticles and the limits of the Debye temperature concept

We present first-principles calculations of the vibrational density of states (VDOS), the specific heat and the mean-squared displacement of the five lowest-energy isomers of Au(13) and of two low-energy FeAu(12) nanoparticles. We find that the vibrational contributions to the Helmholtz energy do not affect the energy ordering of the isomers. As expected, for nanoparticles the vibrational density of states differs dramatically from the function proposed by the Debye model. We demonstrate that, for the nanoclusters we studied, the alternative calculations of the 'Debye temperature' yield significantly inconsistent results. We conclude that T(D) obtained from a particular thermodynamic property is neither applicable for deriving conclusions about other thermodynamic properties nor correlated with atomic bond strengths. Instead, in order to describe the temperature dependence of a nanoparticle's mean-squared displacement and its specific-heat capacity, what is necessary is its discrete phonon spectrum.     

Calculation of the IR Spectrum and the Molecular Structure of β-Carotene

Using the B3LYP/6-31G(d) method, calculations of the structure and the IR spectra of all-trans-β-carotene and its 15,15′-cis-isomer have been performed. The effective harmonic force fields have been obtained and the observed IR bands have been interpreted. Vibrations of the β-ionic ring have been singled out. On the basis of the analogy between the molecular structure of stable radicals and carotenoids of natural origin we set up the hypothesis that the methyl groups of the β-carotene molecule stabilizing the biradical excited triplet state that arises in the process of triplet-triplet energy transfer play a protective, screening role.__________Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 2, pp. 157–164, March–April, 2005.     

Calculation of the binding energy and of the parameters of low-energy scattering in the Λnp system

The cluster-reduction method is used to solve the differential Faddeev equations for S=1/2, T=0 and S=3/2, T=0 spin-isospin states of the Λnp system in the s-wave approximation. The NN interaction is simulated on the basis of the MT I–III potential model, and the ΛN potential is set to V _ΛN =V _NN /2. This simple option makes it possible to reproduce faithfully the binding energy of the hypertriton _Λ ³ H. The doublet and quadruplet Λd scattering lengths and the low-energy phase shifts are calculated. It is shown that the effective-range approximation is applicable to the cases of doublet and quadruplet scattering.     

Dynamics of the normal–superconductor phase transition and the puzzle of the Meissner effect

The analysis of Pippard (1950) for the growth of the normal phase into the superconducting phase in the presence of a magnetic field H>H_c$H>H_c$ is applied in reverse to the case H<H_c$H<H_c$ (H_c=$H_c=$ critical magnetic field). We carry out the analysis both for a planar and a cylindrical geometry. As the superconducting phase grows into the normal phase, a supercurrent is generated at the superconductor–normal phase boundary that flows in direction opposite to the Faraday electric field resulting from the moving phase boundary. This supercurrent motion is in direction opposite to what is dictated by the Lorentz force on the current carriers, and in addition requires that mechanical momentum of opposite sign be transferred to the system as a whole to ensure momentum conservation. In the cylindrical geometry case, a macroscopic torque of unknown origin acts on the body as a whole as the magnetic field is expelled. We argue that the conventional BCS-London theory of superconductivity cannot explain these facts, and that as a consequence the Meissner effect remains unexplained within the conventional theory of superconductivity. We propose that the Meissner effect can only be understood by assuming that there is motion of charge in direction perpendicular to the normal–superconductor phase boundary and point out that the unconventional theory of hole superconductivity describes this physics.     

Investigation of the Excitation of the Static GaseousLasers by the Combined Microwave and DC Discharges

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Evaluation of the Intensities of Spectral Lines under the Influence of Interferences and the Determination of Global Maxima of the Mass–Spectrum Peaks

We describe the technique by which the intensity of spectral lines can be evaluated and the global maxima of the mass–spectrum peaks under the influence of pulse interferences can be defined using an experimental setup based on a commercial MX–7304A mass spectrometer, IBM personal computer (PC), and a digital extremum regulator that allows one to ignore local extrema and bring about automatic search for a global maximum of the mass–spectrum peak and its tracking with an accuracy of 0.0012% at a speed of response of 50 kHz, elevated speeds of the scanning of masses 500 amu/sec, and stability of regulation.     

Update of g-2 of the muon and Δα

We update our Standard Model predictions for g-2 of the muon and for the hadronic contributions （5） 2 to the running of the QED coupling, Δαbad^5）（MZ^2）. Particular emphasis is put on recent changes in the hadronic contributions from new data in the 2π channel and from the energy region just below 2 GeV.     

Representation and Dimensional Reduction of the Universe

The external space we live in or the apparent dimension in the Kaluza-Klein model can be identified by using the right representation in quantum cosmology. The external dimension of the Freund-Rubin model is rain(s, n-s), where s is the rank of the antisymmetric field strength in the model.     

Structure and stability of various states of the EuC and EuC2 molecules

B3LYP level density functional theory （DFT） and multiconfiguration self-consistent-field （MCSCF） level ab initio method calculations have been performed on the basis of relativistic effective core potentials to investigate the nature of EuC and EuC2 molecules. The computed results indicate that the ground states of EuC and EuC2 are ^12∑^＋ and SA2, respectively. Dissociation potential energy curves of the low-lying electronic states of EuC have been calculated using the MCSCF method, and the same level calculation on EuC2 indicates that the dissociation energy of EuC2 of ground state compares well with the available experimental data. The bond characteristic is also discussed using Mulliken populations.     

The triple-α process and the origin of the elements

The triple-α process is the nuclear fusion of helium to carbon. Two ⁴He nuclei collide and form an unstable state of ⁸Be. Before this can decay back a third α-particle collides with it to form a ¹²C nucleus. The reaction rate is probably the most temperature sensitive known to physics because there is a resonant state of the ¹²C nucleus at just the energy of the ⁸Be? and the ⁴He that have the greatest chance of penetrating the Coulomb barrier. The reaction takes place in stars that have exhausted their central hydrogen fuel. Most interesting are the asymptotic giants that can dredge the carbon produced to the surface and return it, perhaps first processing it to nitrogen, to the interstellar medium. The fortuitous energy of the resonant state of ¹²C and its consequences are crucial to the way stars evolve and the abundance of carbon on the Earth.     

Pressure Shifts and Pressure Broadening of the B and γ Bands of Oxygen

Measurements of pressure shift and pressure broadening in molecular oxygen have been made for rotational transitions in the B (1←0) and γ (2←0) vibrational bands of the b¹Σ⁺_g←X³Σ⁻_g visible electronic transition. The absorption features were measured simultaneously in two cells by photoacoustic spectroscopy using a scanning dye laser. The measurements were made with background gases of both pure oxygen and air at room temperature. The pressure shifts were all negative. The measurements show the magnitude of the pressure shift increasing with vibrational quantum number when compared with existing data for the A (0←0) band. The shifts also increase with rotational number within each vibrational band. The shifts in air are larger than in oxygen although the difference gets smaller with vibrational number. The average shifts in air for the A, B, and γ bands were 36, 11, and 0.2% higher, respectively, than in pure oxygen. The pressure broadening of the rotational lines does not change significantly with vibrational number and in general decreases with rotational number within a band. The pressure shift measurements were used by the high-resolution Doppler imager (on the Upper Atmospheric Research Satellite) to correct the Doppler wind measurements.     

Electronic band structures of the alkali metals and of the noble metals and their α-phase alloys

In the monovalent metals the electronic band structure is strongly affected by the size of the band gap E _s-E _p at the Brillouin zone faces, a large gap implying a large distortion of the Fermi surface. Here E _s and E _p are the energies of the purely s-like and p-like states on the zone faces. We have made crude estimates of E _s-E _p for the alkali and noble metals, in terms of the s-p excitation energy Δ_sp of the free atoms. These suggest a single model which correlates most of the experimental information about the band structures of these metals. In particular the Fermi surface of lithium appears to make considerable contact with the zone faces. In the α-phase alloys of the noble metals, the solute always has a larger value of Δ_sp than the solvent, which raises the energy E _p relative to E _s. The Fermi surface becomes more nearly spherical in copper alloys than in copper, since E _p<E _s, whereas it distorts further in the gold alloys (E _p>E _s). This accounts for many Knight shift, electronic specific heat, magnetic susceptibility and other data on these alloys. Furthermore it provides the extension of Jones' explanation of the Hume-Rothery rule demanded by the non-spherical Fermi surface in pure copper and gold.     

Effect of the mesons σ* and Φ and the variety of U(N)Σ on the transition density of hyperon stars

The effect of the mesons σ* and φ and the variety of U(N)Σ on the transition density of hyperon stars is examined within the framework of relativistic mean field theory for the baryon octet {n,p,∧,∑-,∑0,∑+,Ξ- and Ξ0} system.It is found that,compared with that without considering the mesons δ* and φ,the transition density of hyperon stars decreases,the critical baryon density that hyperons Σ-,Σ0,Ξ+,Ξ- and Ξ0 appears to decrease too,but for A the effect is not obvious.As U(N)Σ goes up,the critical baryon density of Σ+,Σ0 and Σ- increases,that of Ξ0 decreases and that of A and Ξ- is fixed.In addition,it is found that the variety of U(N)Σ almost does not influence the transition density.     

Ground-State Properties of Ca Isotopes and the Density Dependence of the Symmetry Energy

A relativistic mean field model is used to study the ground-state properties of neutron-rich nuclei in Ca isotopes. An additional isoscalar and isovector nonlinear coupling has been introduced in the relativistic mean field model, which could soften the symmetry energy, while keep the agreement with the experimental data. The sensitivity of proton and neutron density distributions and single particle states in Ca isotopes to the additional isoscalarisovector nonlinear coupling term is investigated. We found that the binding energies, the density distributions of single particle levels are strongly correlated with the density dependence of the symmetric energy in nuclear matter.     

Square Integrability and Uniqueness of the Solutions of the Kadomtsev–Petviashvili-I Equation

We prove that the solution of the Cauchy problem for the Kadomtsev–Petviashvili-I Equation obtained by the inverse spectral method belongs to the Sobolev space H^k(R²) for k 0, under the assumption that the initial datum is a small Schwartz function. This solution is shown to be the unique solution within a class of generalized solutions of the Kadomtsev–Petviashvili-I equation.     

Role of the Carbohydrate Moiety and of α-L-Fucose in the Stabilization and the Dynamics of the Lens culinaris Agglutinin–Glycoprotein Complex. A Fluorescence Study

Interaction between the fluorescent Lens culinaris agglutinin–fluorescein complex (LCA-FITC) and two glycoproteins, lactotransferrin (LTF) and serotransferrin (STF), was studied. The two glycoproteins have the same glycan structures, with one difference: the lactotransferrin glycans contain a fucose residue -1,6-linked to the N-acetylglucosamine residue involved in the N-glycosylamine linkage. Fluorescence intensity quenching of the LCA-FITC complex shows that affinity between LCA and lactotransferrin is 50 times higher than that between LCA and serotransferrin, the fucose playing a major role in this high affinity (K _a is equal to 9.66 and 0.188 M ^–1 for the LCA–LTF complex and LCA–STF complex, respectively). Time-resolved anisotropy decay indicates that the rotational correlation time of LCA (20 ns) does not change to a large extent whether the glycoproteins are bound to LCA or not. This suggests that there is no extended physical contact between LCA and the glycoproteins. The interaction between LCA and the glycoproteins occurs likely only via the carbohydrate chains, the STF and the LTF rotating almost-freely in the vicinity of LCA, with the glycans as an anchor.     

New results on the moments of the eigenvalues of the Schrödinger Hamiltonian and applications

We show that the moments of order of the eigenvalues of the Schrödinger Hamiltonian inn dimensions can be related to moments of order less than or equal to -1/2 inn+1 dimensions. This makes it possible to improved the bounds on the sum of the eigenvalues in three dimensions and consequently the Lieb-Thiirng bound on the binding energy of matter.