Open Access Published by De Gruyter Open Access

Volume 4 Issue 2

June 2006

Issue of Open Physics

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Journal Overview

Open Access June 1, 2006

Biophysical changes induced by cholesterol on phosphatidylcholine artificial biomembranes containing alamethicin oligomers

Adrian Cernescu, Tudor Luchian

Page range: 155-167

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Abstract

Cholesterol is an important constituent of eukaryotic cell membranes, whose interaction with phospholipids leads to a broad range of biological roles, such as: maintenance of proper fluidity, formation of raft domains, reduction of passive permeability of various chemical species through the bilayer (e.g., glucose, glycerol, K+, Na+ and Cl− ions), and increased mechanical strength of the membrane. In this work we studied an interesting paradigm, as to whether cholesterol-containing phosphatidylcholine biomembranes influence the kinetics and transport features of alamethicin oligomers embedded into it. We demonstrate that moderate relative amounts of cholesterol increase the electrical conductance of various sub-conductance states of the alamethicin oligomer, caused probably by a non-monotonic change in the lumped dipole moment of the biomembrane. Our data suggest that biomembrane stiffness caused by cholesterol, visibly modifies the association-dissociation rates of alamethicin oligomerization in the biomembrane. Moreover, increasing concentrations of cholesterol seem to lead to more stable intermediate alamethicin oligomers. We show that in the presence of cholesterol, as the diameter of the alamethicin oligomer increases, so does the time of another monomer to get picked up. These results brings into focus the interesting issue of how oligomerization of proteins affects their interaction affinities for membrane-based lipids.

Open Access June 1, 2006

A new approach to the use of EMMRS: Ionic Mobility MR Spectroscopy (IMMRS)

Czesław Lewa, Tomasz Klinkosz

Page range: 168-177

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Abstract

A new approach to the use of the previously proposed method called Electrical Mobility Magnetic Resonance Spectroscopy (EMMRS) has been worked out. It consists in obtaining mobility distribution, lifetimes, and activation energy of charge carriers by introducing into the medium a longitudinal elastic wave perpendicular to the electric field which causes displacement of charges (electrons, protons, ions, free radicals, and molecules related with charge carriers) present in the biological environment or inanimate matter. Such a method allows for determination of these quantities within small areas, thus offering possibilities for their imaging. We therefore suggest to call it Ionic Mobility MR Spectroscopy (IMMRS).

Open Access June 1, 2006

Changes of thermal, mechanical and magnetic properties of an amorphous Fe80Cr5B15 alloy during magnetic and structural phase transitions

Paweł Kamasa, Piotr Myśliński

Page range: 178-186

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Abstract

Thermal, mechanical and thermomagnetic properties associated with the magnetic and structural transition of an amorphous Fe80Cr5B15 alloy are described. The investigation was carried out in a simultaneous dilatometric and thermomagnetic experiment. An anomaly of the thermal expansion coefficient at the Curie point and a change in mechanical properties just before the onset of crystallization are observed. The results are compared with the thermal behavior obtained by differential scanning calorimetry.

Open Access June 1, 2006

Influence of ion bombardment on the photoluminescence response of embedded CdS nanoparticles

Dambarudhar Mohanta, Fouran Singh, D. Avasthi, Amarjyoti Choudhury

Page range: 187-195

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Abstract

Semiconductor nanoparticles (CdS) were fabricated by an inexpensive chemical route using polyvinyl alcohol (PVA) as the dielectric host matrix. Nano-CdS in PVA were subjected to ion irradiation (using oxygen, chlorine and gold) in the medium energy range (80–100 MeV) and under fluence variation of 1011–1013 ions/cm2. The nature of light emission was found to be drastically different in each of the three cases. Photoluminescence spectra of oxygen irradiated samples exhibit band edge emission (2.8 eV) as well as trap related emission (1.76 eV) whereas band edge emission is found to be bleached out for chlorine ion irradiated nano-CdS. The intense broad PL peaks, noticeable in the case of gold ion irradiated samples suggest superposition of the two peaks — namely, band edge emission and trap related emission. Furthermore, in the case of gold ion irradiated nano-CdS, energy shift in the PL spectra reveals variation in size distribution caused by the extra pressure effect of heavy gold ion beams. The mechanism of such a difference as a result of ion irradiation-type and ion-fluence is discussed in detail.

Open Access June 1, 2006

Dynamics of two quantum entangled particles interacting with a potential barrier in an EPR experiment

Vittoria Petrillo, Giorgia Alberti, Luca Celardo, Francesco Cerutti, Silvano Franchi, Vittorio Mariani

Page range: 196-209

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Abstract

The effect of a position measurement on one component of a two-particle wave packet in a regularized space-momentum entangled state is analyzed. The wave packet interacts in the physical space with a potential barrier. When a position or momentum measurement is performed on one particle, a consequent strong modification of the dynamics of the other particle occurs.

Open Access June 1, 2006

Translation-rotation coupling and heat transfer in orientationally-disordered phase of CCl4

Oleg Pursky, Vyacheslav Konstantinov

Page range: 210-222

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Abstract

The isochoric thermal conductivity of an orientationally-disordered phase of CCl4 is analysed within a model in which heat is transferred by phonons and above the phonon mobility edge by ”diffusive” modes migrating randomly from site to site. The mobility edge ω0 is found from the condition that the phonon mean-free path cannot become smaller than half the phonon wavelength. The contributions of phonon-phonon, one-, and two-phonon scattering to the total thermal resistance of solid CCl4 are calcualted under the assumption that the different scattering mechanisms contribute additively. An increase in the isochoric thermal conductivity with temperature is explained by suppression of phonon scattering at rotational excitations due to a decrease in correlation in the rotation of neighbouring molecules.

Open Access June 1, 2006

The possibility of time resonance (explosion) phenomena in high-energy nuclear reactions

Vladislav Olkhovsky, Marina Dolinska, Sergey Omelchenko

Page range: 223-240

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Abstract

This study shows that the exponential decrease of the energy spectra, accompanied by slight oscillations, with final-fragment energy in high-energy nuclear reaction, and independent of fragments, targets, projectiles, and projectile energies, can be explained under some conditions in the range of strongly overlapping compound resonances by a new phenomenon of time resonances (explosions). These time resonances (explosions) correspond to the formation of a few highly-excited, non-exponentially decaying nuclear clots (partial compound nuclei consisting of certain small groups of target and projectile nucleons). The proposed approach is an alternative way of analyzing experimental data compared with the majority of known descriptions (for instance, fireball models). This is a new and more general version of the time-evolution approach compared with the Izumo-Araseki time compound-nucleus model.

Open Access June 1, 2006

Decoherence in elastic and polaronic transport via discrete quantum states

Kamil Walczak

Page range: 241-253

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Abstract

In this work we study the effect of decoherence on elastic and polaronic transport via discrete quantum states. Calculations are performed with the help of a nonperturbative computational scheme, based on Green’s function theory within the framework of polaron transformation (GFT-PT), where the many-body electron-phonon interaction problem is mapped exactly into a single-electron multi-channel scattering problem. In particular, the influence of dephasing and relaxation processes on the shape of the electrical current and shot noise curves is discussed in detail under linear and nonlinear transport conditions.

Open Access June 1, 2006

Optical properties of Quantum Disks: Real density matrix approach

Gerard Czajkowski, Leonardo Silvestri

Page range: 254-269

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Abstract

We show how to compute the optical response of a Quantum Disk (QDisk) to an electromagnetic wave as a function of the incident wave polarization, in the energetic region of interband transitions. Both the TM and TE polarization in guided-wave geometry are analyzed. The method uses the microscopic calculation of Quantum Disk eigenfunctions and the macroscopic real density matrix approach to compute the effective QDisk susceptibility, taking into account the valence band structure of the QDisk material and the Coulomb interaction between the electron and the hole. Analytical expressions for the QDisk susceptibility are obtained for a certain model electron — hole potential. Using these expressions, all optical functions can be computed. Results for the absorption coefficient are computed for InAs/GaAs QDisks. Fair agreement with experiments is obtained.

Open Access June 1, 2006

Transient properties of a bistable kinetic model with quantum corrections

Bao-quan Ai, Hua Zheng, Hui-zhang Xie, Liang-gang Liu

Page range: 270-276

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Abstract

The transient properties of a Brownian particle moving in a bistable system with quantum corrections are investigated. The Quantum Smoluchowski Equation (QSE) is fully valid for high temperatures; for low temperatures it is valid only in a restricted domain of the state space. The quantum effects in a bistable system stand out for low temperatures. Explicit expressions of the mean first-passage time (MFPT) are obtained by using a steepest-descent approximation. The quantum effects are against the particle moving towards the destination from its original position.

Open Access June 1, 2006

Multivariate statistical approaches as applied to environmental physics studies

Vasil Lovchinov, Stefan Tsakovski

Page range: 277-298

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Abstract

The present communication deals with the application of the most important environmetric approaches like cluster analysis, principal components analysis and principal components regression (apportioning models) to environmental systems which are of substantial interest for environmental physics — surface waters, aerosols, and coastal sediments. Using various case studies we identify the latent factors responsible for the data set structure and construct models showing the contribution of each identified source (anthropogenic or natural) to the total measure of the pollution. In this way the information obtained by the monitoring data becomes broader and more intelligent, which help in problem solving in environmental physics.

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Open Physics is a peer-reviewed, open access, electronic journal devoted to the publication of fundamental research results in all fields of physics. The journal provides the readers with free, instant, and permanent access to all content worldwide; and the authors with extensive promotion of published articles, long-time preservation, no space constraints and immediate publication.
Open Physics is listed inter alia by Clarivate Analytics (formerly Thomson Reuters) - Current Contents/Physical, Chemical and Earth Sciences, JCR and SCIE. Our standard policy requires each paper to be reviewed by at least two Referees and the peer-review process is single-blind.

The journal publishes research and review articles, rapid and short communications, comments and replies that cover the following areas of physical sciences:

Acoustics
Astrophysics,
Atomic and Molecular Physics,
Biological and Medical Physics,
Complex Networks, Socio- and Econophysics,
Computational Physics,
Condensed Matter Physics,
Cosmology and Gravitation,
Fluid Mechanics,
Geophysics,
Nanophysics,
Optics and Lasers,
Particle and Nuclear Physics,
Plasma Physics,
Statistical and Nonlinear Physics,
Surface Physics,
Theoretical and Mathematical Physics.

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