Use of Adaptive Focused Acoustics™ ultrasound in controlling liposome formation

Many techniques for producing large unilamellar vesicles (LUVs) or small unilamellar vesicles (SUVs) have drawbacks, including exposure of sensitive biological materials to harsh organic solvents or high temperatures. Here we describe the use of controlled focused ultrasound, Adaptive Focused Acoustics™ (AFA), to make LUV or SUV at low temperature without organic solvents and at a consistent, chosen size. We studied the effects of peak incident power (PIP), cycles per burst (CPB), duty factor (DF), temperature, and lipid composition (natural or synthetic), on liposome size distribution. We found that an increase in PIP, DF, CPB, or temperature decreased liposome size. When processed under the same conditions as the natural lipid composition [Phospholipon 90 G], the synthetic lipid composition [HSPC, DSPE-PEG-2000, Chol] generally produced larger liposomes, although extending processing time reduced liposomes to similar size. In combination with AFA, these trends can help pinpoint parameter values that achieve a desired liposome size distribution.     

SU(3) classification of p-wave ηπ and π systems

An exotic meson, the π₁(1400) with J ^PC = 1^{- +}, has been seen to decay into a p-wave ηπ system. If this decay conserves flavor SU(3), then it can be shown that this exotic meson must be a four-quark state ( qˉq + qˉq) belonging to a flavor ˉ10 representation of SU(3). In contrast, the π₁(1600) with a substantial decay mode into π is likely to be a member of a flavor octet. Received: 27 March 2002 / Accepted: 8 August 2002 / Published online: 10 December 2002 RID="b" ID="b"e-mail: klempt@iskp.uni-bonn.de Communicated by V. Vento     

Motion of a 3D exciton in a magnetic field: Exciton-magnetoexciton “phase” transition

A rearrangement of the ground state of a Wannier-Mott exciton upon an increase in its momentum is considered. The phase diagram of the electron and the hole experiencing the Coulomb interaction on the magnetic momentum-external magnetic field plane is investigated. A jumplike exciton-magnetoexciton “phase” transition is observed upon an increase in the momentum in fields B weaker than a certain value B<B _tr1. As momentum P increases above a certain critical value P _tr(B), the ground state of the system changes from the hydrogen-like state polarized by the Lorentz force to the magnetoexciton state in which the average distance 〈 r〉 between the electron and the hole increases jumpwise in the transverse direction relative to the field. As the exciton momentum increases, its wave function is extended along the magnetic field, acquiring the shape of a strongly prolate ellipsoid. It is interesting that the momentum of the transition tends to a finite value P ₀>0 even for B→0. At the point of transition, the exciton energy-momentum relation changes jumpwise from a quadratic law to a relation virtually independent of the momentum. For B<B _tr1, the exciton-magnetoexciton transition becomes blurred.     

Observer of a class of chaotic systems:An application to Hindmarsh–Rose neuronal model

This paper first investigates the observer of a class of chaotic systems, and then discusses the synchronization between two identical Hindmarsh–Rose(HR) neuronal chaotic systems. Both the drive and response systems are assumed to have only one state variable available. By constructing proper observers, some novel criteria for synchronization are proposed via a scalar input. Numerical simulations are given to demonstrate the efficiency of the proposed approach.     

Improve a 3D distance measurement accuracy in stereo vision systems using optimization methods’ approach

This paper presents a 3D distance measurement accuracy improvement for stereo vision systems using optimization methods A Stereo Vision system is developed and tested to identify common uncertainty sources. As the optimization methods are used to train a neural network, the resulting equation can be implemented in real time stereo vision systems. Computational experiments and a comparative analysis are conducted to identify a training function with a minimal error performance for such method. The offered method provides a general purpose modelling technique, attending diverse problems that affect stereo vision systems. Finally, the proposed method is applied in the developed stereo vision system and a statistical analysis is performed to validate the obtained improvements.     

Cy3B™: Improving the Performance of Cyanine Dyes

The spectral properties of a rigidified trimethine cyanine dye, Cy3B have been characterised. This probe has excellent fluorescent properties, good water solubility and can be bioconjugated. The emission properties of this fluorophore have also been investigated upon conjugation to an antibody. This study compared the conjugated emission properties of Cy3B with other commercially available fluorophores emitting at similar wavelengths.     

H∞ consensus control of a class of second-order multi-agent systems without relative velocity measurement

This paper studies consensus control problems for a class of second-order multi-agent systems without relative velocity measurement. Some dynamic neighbour-based rules are adopted for the agents in the presence of external disturbances. A sufficient condition is derived to make all agents achieve consensus while satisfying desired H_∞ performance. Finally, numerical simulations are provided to show the effectiveness of our theoretical results.     

Thermodynamic properties of water–aliphatic alcohol systems in a wide range of parameters

The results of thermal and thermodynamic (phase diagram) property calculations of water–aliphatic alcohol (methanol, ethanol, n-propanol) systems in liquid and vapor phases, as well as supercritical fluid water–methanol systems have been presented. The calculations are based on the polynomial equation of state, represented by expansion of the compressibility factor into a power series of reduced density (ω = ρ/ρ_cr and reduced temperature (τ = T/T _cr)

$$Z = \frac{p}{{RT{\rho _m}}} = 1 + \sum\limits_{i = 1}^m {\sum\limits_{j = 0}^{{n_i}} {\frac{{{a_{ij}}{\omega ^i}}}{{{\tau ^j}}}} } $$

, which describes experimental p,ρ,T,x-dependencies with an average relative error of 1.2%.

     

Features of quasiparticle decay in 2D electronic systems with spin–orbit interaction

The dependence of the width of the spectral function of electrons and holes on the wavevector and excitation energy in a 2D electron system with spin-orbit interaction caused by structural inversion asymmetry is analyzed in the G ⁰ W ⁰ approximation. It is shown that an additional (relative to the generation of electron-hole pairs) channel of hole decay due to emission of a plasmon appears in the case of low electron density. Noticeable spin asymmetry of the spectral function width appears in the region of electron excitations.     

Problems of moving ultrasound penetrative devices in a dispersion medium during drilling of the Moon’s regolith

The paper considers the problem of drilling the regolith of the Moon’s South Pole: the influence of water ice on the elastic properties of the regolith and the movement of an ultrasound penetrative device in a dispersion medium. It is shown that low-frequency vibration action can aid in controlling the viscosity of dispersion systems. The hydrodynamics of the penetrative device’s movement in a dispersion medium is calculated. Estimates are made for the drilling speed at different depths and drilling conditions to ensure the retention of volatile regolith components.     

Weakly nonlinear propagation of focused ultrasound in bubbly liquids with a thermal effect: Derivation of two cases of Khokolov–Zabolotskaya–Kuznetsoz equations

A physico-mathematical model composed of a single equation that consistently describes nonlinear focused ultrasound, bubble oscillations, and temperature fluctuations is theoretically proposed for microbubble-enhanced medical applications. The Khokhlov–Zabolotskaya–Kuznetsov (KZK) equation that has been widely used as a simplified model for nonlinear propagation of focused ultrasound in pure liquid is extended to that in liquid containing many spherical microbubbles, by applying the method of multiple scales to the volumetric averaged basic equations for bubbly liquids. As a result, for two-dimensional and three-dimensional cases, KZK equations composed of the linear combination of nonlinear, dissipation, dispersion, and focusing terms are derived. Especially, the dissipation term depends on three factors, i.e., interfacial liquid viscosity, liquid compressibility, and thermal conductivity of gas inside bubbles; the thermal conduction is evaluated by using four types of temperature gradient models. Finally, we numerically solve the derived KZK equation and show a moderate temperature rise appropriate to medical applications.     

Cooperative emission from an ensemble of three-level Λ radiators in a cavity: An insight from the viewpoint of dynamics of nonlinear systems

Cooperative radiation emitted by an ensemble of three-level optical systems with a doublet in the ground state (Λ scheme), which is placed into a cyclic cavity, is studied theoretically. In contrast to the two-level model of emitters, this process with such a configuration of operating transitions may occur without population inversion in the whole, if the doublet is prepared at the initial instant in a superposition (coherent) state. In the ideal case of a Hamilton system, in which the cavity losses and relaxation in the radiator ensemble are disregarded, the conservation laws are derived, which allow a substantial reduction of the dimension of the phase space of the model (?¹¹ → ?⁵) and the application of methods of dynamics of nonlinear systems for analyzing the three-level superradiance under these conditions. The possibility of different (both quasiperiodic and chaotic) scenarios of the three-level superradiance is demonstrated on the basis of Poincaré’s mappings. Global bifurcation of the system upon a transition from the conventional superradiance regime to inversionless one is revealed. The effects of cavity losses, as well as homogeneous and inhomogeneous broadening in the system of radiators on the regularities found are also discussed.     

Appearance of a purely singular continuous spectrum in a class of random schrödinger operators

We consider a discrete Schrödinger operator on l²() with a random potential decaying at infinity as ¦n¦^–1/2. We prove that its spectrum is purely singular. Together with previous results, this provides simple examples of random Schrödinger operators having a singular continuous component in its spectrum.     

Stability of all-trans-β-carotene under ultrasound treatment in a model system: Effects of different factors,kinetics and newly formed compounds

The effects of factors and kinetics of all-trans-β-carotene degradation under ultrasound treatment in a model system were investigated. The compounds of degradation were also tentatively identified by HPLC-DAD, Raman and FT-IR spectroscopy. The type of solvents and temperature were important factors in determining the degradation reaction. Liquid height, ultrasonic intensity and duty cycle of ultrasound exposure only affected the rate of degradation but did not change the nature of degradation. Degradation rate of β-carotene in dichloromethane was the highest. Degradation rate of β-carotene decreased with increasing of temperature. Degradation kinetics of all-trans-β-carotene under ultrasound fitted first-order reaction at ?5 to 15 °C, and fitted second-order reaction at 25 °C. Degradation products included isomers: 15-cis-β-carotene, di-cis-β-carotene and other compounds with function group of C–O.     

Thermodynamics of a 3 — D charged rotating hairy black hole

In this paper, we consider a charged rotating black hole in three dimensions with a scalar charge, and discuss thermodynamics quantities. We find effects of the black hole parameters on the temperature, entropy, free energy, total energy and specific heat. We also investigate the stability of the black hole and study phase transition. We consider the first law of thermodynamics and find that satisfied.     

Temperature and spatial diffusion of atoms cooled in a 3D lin ⊥lin bright optical lattice

We present a detailed experimental study of a three-dimensional lin⊥lin bright optical lattice. Measurements of the atomic temperature and spatial diffusion coefficients are reported for different angles between the lattice beams, i.e. for different lattice constants. The experimental findings are interpreted with the help of numerical simulations. In particular we show, both experimentally and theoretically, that the temperature is independent of the lattice constant. Received 5 July 2001 and Received in final form 13 August 2001