International Journal of Modern Physics B

Standard results for the fluctuations of thermodynamic quantities are derived under the assumption of sampling identical systems that are in different, not fully equilibrated states. These results apply to fluctuations with time in a particular macroscopic body and can be traced to the fluctuations of thermal occupancy. When many identically prepared — but not identical — systems are studied, mesoscopic fluctuations due to variations from sample-to-sample contribute to the fluctuations of thermodynamic quantities. We study the combined effect of mesoscopic fluctuations and fluctuations of thermal occupancy. In particular, we evaluate the total particle number and specific heat fluctuations in a two-dimensional, noninteracting electron gas in classically integrable and chaotic circumstances.

The soft spinel ferrite system having the general formula Co_1-xZn_xFe₂O₄ with x varying from 0.0 to 0.7 has been prepared by wet-chemical co-precipitation technique. The prepared samples were characterized by XRD technique. The analysis of XRD pattern revealed the formation of single-phase cubic spinel structure. The Bragg peaks in XRD pattern are broader indicating fine particle nature of the sample. XRD data have been used to study structural parameter and cationic distribution in Co–Zn ferrite. The particle size is of nanometer dimension. Cation distribution results suggest that Co²⁺ occupy B-site, Zn²⁺ occupy A-site, and Fe³⁺ occupy both the A- and B-site.

The nanoindentation technique was used to measure the hardness and Young's modulus of semiconductor and metal thin films on a Si(100) substrate under cyclic loading. The results showed that in all instances and at a constant cyclic load that the loading curves overlapped the previous unloading curve and had a small displacement after each cyclic nanoindentation. It was observed that the plastic energies of metal materials from the first loading–unloading cycle were much larger than that observed in semiconductor materials. Furthermore, the hardness and Young's modulus of the thin films decreased when the number of cyclic nanoindentations was increased. The effect of the cyclic loading on the hardness and Young's modulus of semiconductor material was much larger than that of the metal material. Young's modulus, the hardness and the contact stiffness of thin films conform to the relationship that Young's modulus was proportional to the contact stiffness and the square root of the thin film's hardness.

We describe existence conditions and explicitly construct elements for a Heisenberg family in the principal grading of the quantized universal enveloping algebra of an affine Kac–Moody algebra in the Drinfeld formulation.

We investigated the electron transport properties of thiophen-bithiol-based molecular wires through atomic metal–thiophen–metal systems using the first principle methods. Various metal–thiophen–metal atomic systems are constructed with different end atoms (S, Se, and Te). The electron transport of the atomic system is systematically studied by analysis of transmission function, density of states, and current–voltage characteristics of the systems.

Hydrogen-free diamond-like carbon (DLC) thin films were prepared at different repetition rates of laser pulses by pulsed laser ablation of graphite target at room temperature. The microstructure of the thin films was characterized by Raman spectroscopy. Raman measurements showed that sp³ bonded carbon fraction is reduced with increase of repetition rates of laser pulses from 5 to 20 Hz. Optical properties, namely photoluminescence (PL), optical absorption, extinction coefficient (k), and refractive index (n), were measured by fluorescence spectrophotometer, scanning spectrophotometer, and spectroscopic ellipsometer. By changing the repetition rates of laser pulses from 5 to 20 Hz, the PL and optical absorption were gradually increased, while the deposition rate and optical band gap of the films decreased strictly with the increase of repetition rate. The extinction coefficient (k) and refractive index (n) were found to be in the range of 0.468–0.938 and 1.92–2.27, respectively. These results indicate that repetition rate of laser pulses has a strong influence on the microstructure and optical properties of the films. Based on the experimental results, a possible causation about the effect of repetition rate on PL was proposed.

The factorization method of the Hamiltonian in quantum mechanics is used to solve a particular type of Riccati equation. In this paper, He's homotopy perturbation method is applied to a general Riccati equation. The obtained solutions are in recursive sequence forms and, in many cases, these solutions lead to an exact solution. This property generally means that one can solve completely the eigenvalue problem for the Hamiltonian operator. The method is tested on various examples which are revealing the effectiveness and the simplicity of the method.

Ag₂S thin films have been deposited onto fluorinated tin oxide (FTO)-coated conducting glass substrates using chemical bath deposition (CBD) method. Photoelectrochemical (PEC) cell, optical properties, surface morphology, structural properties, compositional analysis and electrical properties of Ag₂S thin films have been investigated. The PEC measurements indicate that the deposited Ag₂S layers are n-type in electrical conduction. The transmittance of deposited layer is obtained to be about 13–87%. The absorbance of the films is found to decrease with increasing wavelength. The band gap of the Ag₂S thin film is estimated to be 1.8 eV. It is observed from scanning electron microscopy (SEM) and atomic force microscopy (AFM) measurements that the substrates are well-covered with the deposited Ag₂S layers without cracks and pinholes. The grain size of Ag₂S thin films is estimated from SEM measurements to be in the range 100–210 nm. The mean roughness of Ag₂S films is found from AFM measurements to be in the range 7.20–15 nm. X-ray diffraction shows that the films are well-crystallized and the deposited layers are mainly consisting of Ag₂S phase with (-103) preferential plane. EDX analysis shows that a nearly stoichiometric composition of Ag₂S is obtained. The resistivity is estimated to be in the range 3.5–7.0 Ω-cm.

In this work the mechanism of resonance is proposed as the way for determining of wall paint age. The method consists in accelerated growing old of wall paint on the basis of resonance. Measuring is concerned with the humidity of wall paint and it is a general method since water molecules are present in every material. Besides, the water molecules are dipoles so that the resonance with them can be achieved by the mechanical as well as the electrical way.

Phase synchronization between linearly and nonlinearly coupled systems with internal resonance is investigated in this paper. By introducing the conception of phase for a chaotic motion, it demonstrates that the detuning parameter σ between the two natural frequencies ω₁ and ω₂ affects phase dynamics, and with the increase in the linear coupling strength, the effect of phase synchronization between two sub-systems was enhanced, while increased firstly, and then decayed as nonlinear coupling strength increases. Further investigation reveals that the transition of phase states between the two oscillators are related to the critical changes of the Lyapunov exponents, which can also be explained by the diffuse clouds.