pH-dependent multiple morphologies of novel aggregates of carboxyl-terminated polymide in water

Rigid low-molecular-weight polyimide with two carboxyl ends (CPI) formed pH-dependent multiple morphologies including dimpled-beads, porous aggregates and vesicles via self-assembly in aqueous media. This is a rapid and conventional approach to a series of pH-dependent morphologies of mono-component aggregates based on a readily attainable rigid homopolymer.Received: 27 August 2004, Published online: 10 November 2004PACS: 81.16.Dn Self-assembly - 82.70.Uv Surfactants, micellar solutions, vesicles, lamellae, amphiphilic systems, (hydrophilic and hydrophobic interactions)     

Probing Proteins in Solution by Xe NMR Spectroscopy

The interaction of xenon with different proteins in aqueous solution is investigated by ¹²⁹Xe NMR spectroscopy. Chemical shifts are measured in horse metmyoglobin, hen egg white lysozyme, and horse cytochrome c solutions as a function of xenon concentration. In these systems, xenon is in fast exchange between all possible environments. The results suggest that nonspecific interactions exist between xenon and the protein exteriors and the data are analyzed in term of parameters which characterize the protein surfaces. The experimental data for horse metmyoglobin are interpreted using a model in which xenon forms a 1:1 complex with the protein and the chemical shift of the complexed xenon is reported (Locci et al., Keystone Symposia “Frontiers of NMR in Molecular Biology VI”, Jan. 9–15, 1999, Breckenridge, CO, Abstract E216, p. 53; Locci et al., XeMAT 2000 “Optical Polarization and Xenon NMR of Materials”, June 28–30, 2000, Sestri Levante, Italy, p. 46).     

Some exact solutions of F(R) gravity with charged (a)dS black hole interpretation

In this paper we obtain topological static solutions of some kind of pure F(R) gravity. The present solutions are two kind: first type is uncharged solution which corresponds with the topological (a)dS Schwarzschild solution and second type has electric charge and is equivalent to the Einstein-Λ-conformally invariant Maxwell solution. In other word, starting from pure gravity leads to (charged) Einstein-Λ solutions which we interpreted them as (charged) (a)dS black hole solutions of pure F(R) gravity. Calculating the Ricci and Kreschmann scalars show that there is a curvature singularity at r = 0. We should note that the Kreschmann scalar of charged solutions goes to infinity as r → 0, but with a rate slower than that of uncharged solutions.     

The anisotropic multichannel spin-$\mathsf{S}$ Kondo model: Calculation of scales from a novel exact solution

A novel exact solution of the multichannel spin-S Kondo model is presented, based on a lattice path integral approach of the single channel spin-1/2 case. The spin exchange between the localized moment and the host is of XXZ-type, including the isotropic XXX limit. The free energy is given by a finite set of non-linear integral equations, which allow for an accurate determination of high- and low-temperature scales.Received: 9 June 2004, Published online: 3 August 2004PACS: 72.15.Qm Scattering mechanisms and Kondo effect - 04.20.Jb Exact solutions - 75.20.Hr Local moment in compounds and alloys; Kondo effect, valence fluctuations, heavy fermions - 75.10.Lp Band and itinerant models     

AG 2 II algebraically general twistfree vacuum spacetime

Several authors, e.g., Kerr and Debney (1970), Lun (1978), have obtained severalG ₂ II algebraically special vacuum solutions. NoG ₂ II algebraically general vacuum solutions in explicit form have been found before. In this paper, we start from a system of first order partial differential equations, obtained by using a triad formalism, which determines twistfree vacuum metrics with a spacelike Killing vector. The method of group-invariant solutions is then used and aG ₂ II algebraically general twistfree vacuum solution is obtained. The solution also admits a homothetic Killing vector and is non-geodesic. It is believed to be new. The following explicit solutions are also obtained: (1) A Petrov type II with aG ₁-group of motions solution which belongs to Kundt's class. (2) A Petrov type III,G ₃ Robinson-Trautman solution. All these solutions are known.     

Coulomb wave function corrections for n-particle Bose–Einstein correlations

The effect of multi-particle Coulomb final state interactions on higher-order intensity correlations is determined in general, based on a scattering wave function which is a solution of the n-body Coulomb Schr?dinger equation in (a large part of) the asymptotic region of n-body configuration space. In particular, we study Coulomb effects on the n-particle Bose–Einstein correlation functions of similarly charged particles and remove a systematic error as big as 100% from higher-order multi-particle Bose–Einstein correlation functions. Received: 24 November 1999 / Published online: 17 March 2000     

Dissociative ionization of molecules in intense laser fields

Accurate and efficient grid based techniques for the solution of the time-dependent Schrödinger equation for few-electron diatomic molecules irradiated by intense, ultrashort laser pulses are described. These are based on hybrid finite-difference, Lagrange mesh techniques. The methods are applied in three scenarios, namely H₂ ⁺ with fixed internuclear separation, H₂ ⁺ with vibrating nuclei and H₂ with fixed internuclear separation and illustrative results presented.Received: 19 November 2002, Published online: 24 April 2003PACS: 02.60.Cb Numerical simulation; solution of equations - 02.70.Bf Finite-difference methods - 33.80.Rv Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states) - 33.80.-b Photon interactions with molecules     

Theoretical investigation of high-pressure phase transitions in Mg1-xSrxO

The stability of Mg_1-xSr_xO solid solution has been analyzed using charge transfer interaction potential (CTIP) model as well as density functional theory-based ab initio approach with Perdew–Burke–Ernzerhof (PBE) type parameterized generalized gradient approximation. The present CTIP model consists of long-range part as modified coulomb interactions and charge transfer forces whereas short-range part includes the van der Waals as well as Hafemeister Flygare type overlap repulsive interactions effective up to next nearest neighbor ions. The present study finds that under the influence of pressure host binary oxides as well as their solid solutions undergo B1→B2 structural phase transition in the pressure range of 54–495 GPa. The variation of ground state properties and transition pressures have also been analyzed as a function of Sr composition. The observed results for the end point members are in agreement to their experimental counterparts and the deviations have been discussed in terms of interactions taken into consideration in two approaches.     

Matrix KP: tropical limit and Yang–Baxter maps

We study soliton solutions of matrix Kadomtsev–Petviashvili (KP) equations in a tropical limit, in which their support at fixed time is a planar graph and polarizations are attached to its constituting lines. There is a subclass of “pure line soliton solutions” for which we find that, in this limit, the distribution of polarizations is fully determined by a Yang–Baxter map. For a vector KP equation, this map is given by an R-matrix, whereas it is a nonlinear map in the case of a more general matrix KP equation. We also consider the corresponding Korteweg–deVries reduction. Furthermore, exploiting the fine structure of soliton interactions in the tropical limit, we obtain an apparently new solution of the tetrahedron (or Zamolodchikov) equation. Moreover, a solution of the functional tetrahedron equation arises from the parameter dependence of the vector KP R-matrix.

     

Long-Time Asymptotics for Strong Solutions¶of the Thin Film Equation

In this paper we investigate the large-time behavior of strong solutions to the one-dimensional fourth order degenerate parabolic equation u _t =−(u u _xxx ) _x , modeling the evolution of the interface of a spreading droplet. For nonnegative initial values u ₀(x)∈H ¹(ℝ), both compactly supported or of finite second moment, we prove explicit and universal algebraic decay in the L ¹-norm of the strong solution u(x,t) towards the unique (among source type solutions) strong source type solution of the equation with the same mass. The method we use is based on the study of the time decay of the entropy introduced in [13] for the porous medium equation, and uses analogies between the thin film equation and the porous medium equation. Received: 2 February 2001 / Accepted: 7 October 2001     

The solar-neutrino problem, 1995

Summary The status of the Solar-Neutrino Problem (SNP), as is seen in 1995, is reviewed. Basically, there are two principal solutions to the SNP: i) withstandard neutrino (neutrino of SM of electroweak interactions) and ii) withnon-standard neutrino (neutrino beyond the SM). Actually, one can distinguish three solar-neutrino problems: the deficit of⁸B neutrinos, the deficit of⁷Be neutrinos and the HOMESTAKE/KAMIOKANDE conflict. The first problem probably can be solved with small correlated changes of nuclear cross-sections and the change of the central temperature of the Sun. The deficit of⁷Be neutrinos looks like the key problem. The HOMESTAKE/KAMIOKANDE conflict strongly disfavours or excludes the standard neutrino (nuclear/astrophysical solution to the SNP). MSW conversion gives a most plausible explanation to the SNP.     

Ascending air bubbles in protein solutions

We report measurements of the ascending velocity of air bubbles in protein (bovine serum albumin) solutions. We show that, because of the protein molecules adsorbed on their surface, the terminal ascending velocity of bubbles is strongly reduced compared to the terminal velocity in pure water: protein- covered bubbles behave hydrodynamically as solid spheres. From the evolution of the ascending velocity with time, we can derive the amount of protein needed to immobilize the bubble interface which is 0.5 mg m^-2, i.e. only one fifth of the amount adsorbed at equilibrium in the range of used bulk concentrations. Received: 6 March 1998 / Revised and accepted: 6 May 1998     

Exact solutions of a one-dimensional mixture of spinor bosons and spinor fermions

The exact solutions of a one-dimensional mixture of spinor bosons and spinor fermions with δ-function interactions are studied. Some new sets of Bethe ansatz equations are obtained by using the graded nest quantum inverse scattering method. Many interesting features appear in the system. For example, the wave function has the SU(2|2) supersymmetry. It is also found that the ground state of the system is partial polarized, where the fermions form a spin singlet state and the bosons are totally polarized. From the solution of Bethe ansatz equations, it is shown that all the momentum, spin and isospin rapidities at the ground state are real if the interactions between the particles are repulsive; while the fermions form two-particle bounded states and the bosons form one large bound state, which means the bosons condensed at the zero momentum point, if the interactions are attractive. The charge, spin and isospin excitations are discussed in detail. The thermodynamic Bethe ansatz equations are also derived and their solutions at some special cases are obtained analytically.     

Evolution of plane-symmetric self-similar space-times containing perfect fluid

Space-times with plane symmetry are considered which also admit a conformal group such that the metric depends on the variablez=x ¹/x ⁰ (homothetic or self-similar solutions). Different regions depending on the space-time character ofz can be discerned in each solution: thet region whenz is timelike and thes-region whenz is spacelike. Exact solutions of the Einstein equations are given for an energy-momentum tensor corresponding to an ideal fluid with equation of statep=(-1)e. Different types of solutions occur depending upon the value of in the equation of state, and these are studied using phase-plane methods. The solutions of considered type in the Minkowski space-time are also given.     

Decay of Solutions of the Wave Equation in the Kerr Geometry

We consider the Cauchy problem for the massless scalar wave equation in the Kerr geometry for smooth initial data compactly supported outside the event horizon. We prove that the solutions decay in time in L ^∞ _loc. The proof is based on a representation of the solution as an infinite sum over the angular momentum modes, each of which is an integral of the energy variable ω on the real line. This integral representation involves solutions of the radial and angular ODEs which arise in the separation of variables. Research supported in part by the Deutsche Forschungsgemeinschaft. Research supported by NSERC grant #RGPIN 105490-2004. Research supported in part by the NSF, Grant No. DMS-010-3998. Research supported in part by the NSF, Grant No. 33-585-7510-2-30. An erratum to this article is available at .     

Ann monopole solution with 4n — 1 degrees of freedom

An exact static monopole solution, possessingn units of magnetic charge and (4n-1) degrees of freedom, is constructed, generalising the recent work of Ward on two monopole solutions. The equations solved are those of anSU(2) gauge theory with adjoint representation Higgs field in the (BPS) limit of vanishing Higgs potential. The number of degrees of freedom is maximal for self-dual solutions. The construction is described in a deductive way, within the framework of the Atiyah-Ward formalism for self-dual gauge fields.     

A radiation dose study based on analysis of primary color chrominance

Purpose: The purpose of this study was to assess the possibility of measuring radiation dose based on primary color chrominance in chemical solutions. Methods: We used an aqueous solution with different concentrations of Alphaurine A and Tracid Brilliant Red B. This was irradiated by 1.5–13.5?kGy ⁶⁰Co γ radiation. Data were collected by an instrument that can detect information on the three primary colors. Data were analyzed and manipulated for each experiment. Results and conclusions: The result shows that three primary colors chrominance in the aqueous solutions change with different doses of ⁶⁰Co γ-rays and different concentrations of Alphaurine A and Tracid Brilliant Red B. For Alphaurine A, the red chrominance is gradually reduced as a function of radiation dose. The blue chrominance gradually increases concurrently. The red and green chrominance changes obviously and inversely, but the green chrominance changes little. In Tracid Brilliant Red B solution, the red chrominance gradually decreases as the radiation dose increases. The green chrominance gradually increases concurrently. The red and green chrominance changes are obvious and inverted. The blue chrominance changes little. Our experiments demonstrate that radiation dose can be studied based on three primary colors chrominance. This may be a new tool to measure the radiation dose.     

Analyses of HF/NH4F buffer-treated Si(111) surfaces using XPS,REM and SIMS

The effect of different cleaning procedures on Si(111) wafers has been studied. A three-step cleaning process was used. The first two steps (thermal oxidation followed by RCA cleaning) were common to all samples. The final step involved rinsing in one of a set of HF/NH4F buffer solutions with a wide range ofpH values. Three different surface techniques were used for characterizing the chemical condition and morphology of the treated surfaces: XPS (X-ray Photoemission Spectroscopy), REM (Reflection Electron Microscopy) and SIMS (Secondary-Ion Mass Spectroscopy). It has been found that thepH value of an HF solution does significantly affect the etching rate and morphology of the Si(111) surface: For the same type of solution, the smaller thepH value, the higher the etching rate. Basic solutions withpH values larger than eight have a much weaker etching effect on the surface, which is contradictory to some previous reports. The most effective solutions for the etching of the Si(111) surface are the solutions of HF buffered by NH₄F, with thepH in the range of 2–6. REM images indicate that the surface morphology after etching in the HF solution is strongly affected by the length of the etching time: Overetching will roughen the surface. The SIMS data show that water rinsing in air during the cleaning process does speed up oxidation, but it is necessary to use water to clean off the residuals from the HF solutions.