Measurements of indoor radon concentration levels in Kilis,Osmaniye and Antakya,Turkey during spring season

The fact that 50% of the natural radiation dose to which humans are exposed is caused by radon gas makes indoor radon measurements important. In this study, levels of indoor radon gas were measured in 204 houses in Kilis, Osmaniye and Antakya using passive nuclear track detectors. Cr-39 radon detectors were left in the living rooms of participants’ houses, then analyzed at the Radon Laboratory of Health Physics Department in Çekmece Nuclear Research and Training Center (ÇANEM) of Atomic Energy Agency of Turkey (TAEK). Average indoor radon activity concentrations for Kilis, Osmaniye and Antakya were 50 Bq/m³ (1.26 mSv/y), 51 Bq/m³ (1.29 mSv/y) and 40 Bq/m³ (1.01 mSv/y), respectively.     

Comparative characterisation of zinc oxide thin films prepared from zinc acetate with or without water of hydration via the sol–gel method

Zinc oxide thin films were prepared using either zinc acetate dihydrate or anhydrous zinc acetate via the sol–gel method. Comparative characterisation of the crystallographical, morphological, optical/spectroscopical and electrical properties of the so-obtained films was performed. The idea of one- (in the case of the anhydrous precursor), and two- (in the other case) stage hydrolysis/condensation was postulated, which was supported by the characterisation results. The film prepared using the anhydrous precursor had a more pronounced c-axis crystal orientation preference, with a larger average crystallite size and more porous morphology. The transparency of this film was significantly lower over the UV/visible region due to its more porous morphology, which also resulted in lower intensity of the ‘near band edge emission’, and higher electrical resistivity. The overall results also suggested that anhydrous zinc acetate could be employed as a precursor for the sol–gel synthesis of zinc oxide thin films, which might have potential advantages in microelectronic and optoelectronic applications.     

Antibacterial glass films prepared on metal surfaces by sol–gel method

This paper describes the preparation and characterization of glass films consisting of SiO₂, Li₂O, Na₂O, K₂O or MgO in varying compositions on stainless steel and aluminum substrates by sol–gel method. Silver phosphate or silver incorporated zeolite was also introduced into the sols for obtaining antibacterial effect. The SiO₂/Li₂O/Na₂O system having the composition of 85:5:10 wt% was found as the optimum for obtaining a stable sol and film formation. The films were investigated by scanning electron microscopy (SEM) and electron dispersive analysis by X-ray (EDX), Fourier transformed infrared (FTIR) spectroscopy, thermo-gravimetric analysis (TGA) and differential thermal analysis (DTA). Homogenous films having 300 ± 20 nm thicknesses were formed by spin coating and then by curing at 500 °C for 1 h. Obtained films had high adherence to the metal substrates and they were also durable in acidic, basic or NaCl environments. They also presented a powerful antibacterial effect against E. coli.     

Sol–gel derived mesoporous and microporous alumina membranes

Stable polymeric and colloidal boehmite sols were prepared by sol–gel process through controlled hydrolysis/condensation reactions. The particle sizes of the colloidal sols were in the 12–25 nm range depending on the process parameters and about 2 nm for polymeric sols. The presence of a significant increase in the microporosity content of the heat treated polymeric membranes relative to the mesoporous colloidal membranes might make the design of thermally stable microporous alumina membranes with controlled pore structures possible. The phase structure evolution in the 600–800 °C range had shown that the crystallization of the gamma alumina in the amorphous matrix starts at about 800 °C. This indicated that the pore structure stability may be enhanced through processing up to this relatively high temperature in polymeric alumina derived unsupported membranes. The permeance values of the two and three layered colloidal alumina membranes were observed to be independent of pressure which implies that the dominant gas transport mechanism is Knudsen diffusion in these structures. This was also supported by the 2.8 nm BJH pore sizes of the colloidal membranes. The Knudsen diffusion equation derived permeances of the polymeric alumina membranes with thicknesses of about 300 nm were determined to be very close to the experimentally determined permeance values.     

Synthesis,Crystal Structure Properties of {μ-Nitrato-[<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′-ethylene-bis(3-methoxysalicylideneimin) diaqua nitrato Cu(II)La(III)]nitrat}

Abstract  

The [μ-NO₃-LCuLa(NO₃)·(H₂O)₂]NO₃ (I) complex has been prepared and characterized by single crystal X-ray diffraction properties. The title compound crystallizes in the monoclinic system, space group P 2₁/c, with a = 9.1699(4), b = 21.6796(8), c = 13.7068(6) ?, α = γ = 90o, β = 111.308(3)°, V = 2538.63 (18) ?³ and Z = 4. The unit cell contains four discrete the title compounds. The central region is occupied by Cu^II and La^III ions which are brigged by two phenolato oxygen atoms of ligand. The intramolecular La–Cu distance is 3.5016 (3) Ǻ. The copper (II) ion is in a distorted square pyramidal geometry with the imino nitrogen atoms N1 and N2, and the phenolic oxygen atoms O2 and O3 forming the square base. The La^III ion is deca coordinated.     

An empirical comparison of conventional techniques,neural networks and the three stage hybrid Adaptive Neuro Fuzzy Inference System (ANFIS) model for credit scoring analysis: The case of Turkish credit card data

The number of Non-Performing Loans has increased in recent years, paralleling the current financial crisis, thus increasing the importance of credit scoring models. This study proposes a three stage hybrid Adaptive Neuro Fuzzy Inference System credit scoring model, which is based on statistical techniques and Neuro Fuzzy. The proposed model’s performance was compared with conventional and commonly utilized models. The credit scoring models are tested using a 10-fold cross-validation process with the credit card data of an international bank operating in Turkey. Results demonstrate that the proposed model consistently performs better than the Linear Discriminant Analysis, Logistic Regression Analysis, and Artificial Neural Network (ANN) approaches, in terms of average correct classification rate and estimated misclassification cost. As with ANN, the proposed model has learning ability; unlike ANN, the model does not stay in a black box. In the proposed model, the interpretation of independent variables may provide valuable information for bankers and consumers, especially in the explanation of why credit applications are rejected.     

Computation of the fundamental solution of electrodynamics for anisotropic materials

A new method for computation of the fundamental solution of electrodynamics for general anisotropic nondispersive materials is suggested. It consists of several steps: equations for each column of the fundamental matrix are reduced to a symmetric hyperbolic system; using the Fourier transform with respect to space variables and matrix transformations, formulae for Fourier images of the fundamental matrix columns are obtained; finally, the fundamental solution is computed by the inverse Fourier transform. Applying the suggested approach, the fundamental solution components are computed in general anisotropic media. Computational examples confirm robustness of the suggested method.     

Studies on Equation-of-State Parameters and Linear Polymer Dimensions of Poly(p-chlorostyrene) in Diethylene Glycol Monobutyl Ether by Intrinsic Viscosity Measurements

Summary. Intrinsic viscosities, [η], of poly(p-chlorostyrene) (PPCS) in diethylene glycol monobutyl ether (DGMBE) which exhibits an exothermic solubility behavior with the polymer were measured using an Ubbelohde type capillary viscometer between 25 and 85°C. Polymer solvent interaction parameters at infinite dilution (χ₁), exchange energy parameter , exchange enthalpy (X₁₂), and entropy parameters (Q₁₂), of the PPCS/DGMBE pair were found at studied temperature range according to equation-of-state theory. In the blob theory, dependence of [η] on temperature can be scaled by a master curve in a plot of α_η³|τ|M^1/2 versus |τ|M^1/2 as the polymer coil contracts below the Θ-point, however, it can be scaled by a master curve in a plot of α_η⁻⁵|τ|M^1/2 versus |τ|M^1/2 as the polymer coil expands above the Θ-point in an endothermic solubility behavior. Since the studied PPCS/DGMBE system represents exothermic solubility behavior, the master curves of the system were plotted in α_η³|τ|M^1/2 versus |τ|M^1/2 as the polymer coil contracts above the Θ-point and in α_η⁻⁵|τ|M^1/2 versus |τ|M^1/2 as the polymer coil expands below the Θ-point. The universal plots of α_η(N/N_c)^1/6 versus N/N_c and α_η(N/N_c)^−1/10 versus N/N_c were plotted above and below Θ-point, respectively.     

Radial-type complete solutions for a class of partial differential equations

We give some fundamental solutions of a class of iterated elliptic equations including Laplace equation and its iterates.