Optical properties of lithium titanate as a potential layer in light harvesters

Journal of Materials Science: Materials in Electronics - Various solar cell architectures and materials are currently studied, seeking enhanced photon management mechanisms. Herein, we provide an...     

A Robust Approach for Locating and Assessing Mechanical Faults in an Actual Transformer Winding Using the State Space of Its Lumped Equivalent Model

Russian Journal of Nondestructive Testing - Transfer function and state-space model are two powerful complementary tools have been used to monitoring the physical system. These two ways can be very...     

Breast cancer metastasis-associated genes: prognostic significance and therapeutic implications

The metastatic spread of breast cancer accounts for most of its morbidity and mortality; therefore, identifying the genes and gene products involved in breast cancer metastasis formation should be useful for better diagnosis, prognosis, treatment, and follow-up of patients with metastatic breast cancer. Unfortunately, little is known about these genes or the functions of their encoded products. Abnormalities in at least three broad gene categories (oncogenes, regulatory genes or effector genes, and tumor-suppressor genes) have been shown to contribute to the origin and/or progression of breast neoplasias. Such abnormalities are mainly manifested by quantitative changes in gene expression, resulting in loss of normal cellular regulation and enhanced cellular diversification. In addition, qualitative genetic alterations, such as gene amplifications and mutations, may also be involved in breast cancer progression. The role(s) of different breast cancer metastasis-associated genes, if known, in the complex multistep process of invasion and metastasis is discussed along with studies that have identified new molecular probe(s) that may be useful in predicting metastasis formation and outcome in breast cancer and for selecting candidates for adjuvant therapy. Understanding the genetic and thus molecular basis of metastasis formation should also provide important insights on the development of new therapeutic approaches for treatment of metastatic breast cancers based on gene targeting and repair of genetic defects that control metastatic properties.     

Infrared spectra,X-ray investigations and electrical conductivity of lithium borosilicate glasses containing transition metal oxides

The conductivities of lithium borosilicate glasses containing 2.5 mol % V₂O₅, MnO, Cr₂O₃, Fe₂O₃ and CoO were measured for untreated and heat-treated glasses (for 5 h at 480, 580 and 680°C). Both IR and X-ray diffraction techniques were used to investigate the microstructure of these glasses before and after heat-treatment. Lithium metasilicate and lithium metaborate were the main separated phases in addition to lithium disilicate in samples containing Fe₂O₃. The silicon ions are coordinated to four oxygens in tetrahedral coordination and some borons changed from triangular to tetrahedral.     

Reliability model of series-parallel systems

Markov models are used to obtain closed form solutions of the reliability of a series-parallel system. The system consists of two identical equipment in series. Each equipment has one component. To improve equipment reliability, extra component is connected in parallel with the original one. Therefore; each equipment is considered as 2-component fault-tolerant one. The component has a Poisson failure, and a repair of contant rate. The system fails if at least one equipment is out of order.     

Optical Properties of Silver Halide Photochromic Glasses Doped with Cobalt Oxide

Photochromic glasses having composition (SiO₂)₄₅(B₂ O ₃)₃₅(Al₂O₃)_7.5(Na₂O)_12.5(AgBr), (Cu₂O) doped with (CoO) _x , in which, x = 0, 0.006, 0.02 and 0.07 g were prepared using the conventional melt technique. The amorphous nature of these glass samples was confirmed using X-ray diffraction analysis at room temperature. The absorption measurements in the infrared region of the spectrum were recorded in the wave number range (4000–400) cm^?1. Spectral reflectance and transmittance at normal incidence of the prepared glass samples were recorded with a spectrophotometer in the spectral range 200–2500 nm. Experimental and theoretical densities of the prepared glass samples were measured, calculated and compared. Analytical expressions were used to calculate the real and imaginary parts of the refractive indices. Dispersion parameters such as: single oscillator energy, dispersion energy, average oscillator wavelength, and Abbe’s number were deduced and compared. Absorption dispersion parameters such as: optical energy gap for direct and indirect transitions, Urbach energy and steepness parameter were calculated. Effects of doping with cobalt oxide CoO as a transition metal on linear and predicted nonlinear optical parameters were investigated and interpreted. Experimental results indicate that there is an optimum concentration of cobalt doping around 0.006 g. The optical band gap decreases with increasing doping and causes an increase in nonlinear optical parameters. Doping with cobalt oxide improves the linear and nonlinear optical properties of the prepared glasses.     

Spectral width reduction using apodized cascaded fiber Bragg grating for post-dispersion compensation in WDM optical networks

This paper proposes a system that aims to reduce the spectral width, Δλ, of the optical signal at transmitter for WDM system over distance 100 km. Also, a chirped fiber Bragg grating (CFBG) at the receiver is used to compensate dispersion. The proposed system consists of four cascaded FBGs connected between light source and optical fiber. Many apodization functions are investigated to enhance the performance of the FBG in the proposed system, and Δλ is obtained at every stage and apodization function. The Q-factor and bit error rate (BER) are obtained at distances 30, 40 and 50 km. It is found that Cauchy apodization function is the best one that reduces the reflective spectral width, Δλ, and achieves a maximum Q-factor and minimum BER at distances 30, 40 and 50 km at the last stage.

     

Synthesis of urea-modified MnFe<Subscript>2</Subscript>O<Subscript>4</Subscript> for aromatic micro-pollutants adsorption from wastewater: Mechanism and modeling

Amine-terminated MnFe₂O₄, using urea solution (UMF-MNPs) fabricated by a combined ultrasonic/microwave technique, was characterized and applied as a magnetic adsorbent to remove catechol, phenol, and benzene micro-pollutants from wastewater solutions. The simultaneous effect of solution pH, TDS, micro-pollutants concentrations, UMF-MNPs dose, and temperature was investigated and optimized using D-optimal design in a batch experiment. The quadratic regression, as the best-structured simulated model, predicted the maximum adsorption rates at pH 6.0, TDS 1855 mg/l, UMF-MNPs dose of 0.73 g/l, and temperature 320 K for 50 mg/l micro-pollutant concentrations. Kinetic and isotherm models, through linear and nonlinear regression methods, reflected an excellent correlation (R ² ≈ 0.83 to 1) to simulate the adsorption data. The column breakthrough curves were tested using the equivalent length of the unused bed approach, which well fitted the Thomas model equation. The film diffusion, consequently with Lewis acid–base, is the major rate-controlling adsorption mechanism, and recovered by alkali ethanolic solution.     

Deterministic and Stochastic Fractional Order Model for Lesser Date Moth

In this paper, a deterministic and stochastic fractional order model for lesser date moth (LDM) using mating disruption and natural enemies is proposed and analysed. The interaction between LDM larvae, fertilized LDM female, unfertilized LDM female, LDM male and the natural enemy is investigated. In order to clarify the characteristics of the proposed deterministic fractional order model, the analysis of existence, uniqueness, non-negativity and boundedness of the solutions of the proposed fractional-order model are examined. In addition, some sufficient conditions are obtained to ensure the local and global stability of equilibrium points. The occurrence of local bifurcation near the equilibrium points is investigated with the help of Sotomayor’s theorem. Numerical simulations are conducted to illustrate the properties of the proposed fractional order model with respect to the intrinsic growth rate of the LDM larvae, natural enemy’s mortality rate, predation rate, sex pheromone trap parameter, fractional order and environmental noise. The impact of mating disruption on lesser date moth is demonstrated. Also, a numerical approximation method is developed for the proposed stochastic fractional-order model.