Kinetika neizotermne kristalizacije kalkogenidnog stakla Sb10Ge10Se80

A differential scanning calorimetry technique was used to study the crystallization kinetics of Sb10Ge10Se80 chalcogenide glass under non-isothermal conditions. The crystallization parameters such as the order parameter (n), the frequency factor (k0), the activation energy of crystallization (Ec), the activation energy of glass transition (Eg) and the activation energy of nucleation (En) were determined. The value of Ec was deduced by means of six methods and the average value was found to be equal to (76.10±1.10) kJmol−1 . The most suitable method for crystallization kinetic studies was the Augis–Bennett approximated method at different heating rates, while the method of Coats–Redfern–Sestak was the most suitable one at constant heating rate. The results have been discussed on the basis of theoretical principles.Primijenili smo diferencijalnu pretražnu kalorimetriju za proučavanje kinetike kristalizacije kalkogenidnog stakla Sb10Ge10Se80 u neizotermnim uvjetima. Odredili smo sljedeće parametre kristalizacije: parametar reda (n), faktor frekvencije (k0), aktivacijsku energiju kristalizacije (Ec), aktivacijsku energiju staklenog prijelaza (Eg) i aktivacijsku energiju nukleacije. Ec smo izveli na osnovi šest metoda i našli srednju vrijednost (76.10 ± 1.10) kJmol−1 . Najpogodnija metoda za proučavanje kinetike kristalizacije za različite brzine grijanja je Augis–Bennettova približna metoda, dok se metoda Coats–Redfern–Sestak-a pokazala najbolja za stalnu brzinu grijanja. Postignuti ishodi raspravljaju se na osnovi teorijskih postavki

Kinetika neizotermne kristalizacije kalkogenidnog stakla Sb10Ge10Se80

A differential scanning calorimetry technique was used to study the crystallization kinetics of Sb10Ge10Se80 chalcogenide glass under non-isothermal conditions. The crystallization parameters such as the order parameter (n), the frequency factor (k0), the activation energy of crystallization (Ec), the activation energy of glass transition (Eg) and the activation energy of nucleation (En) were determined. The value of Ec was deduced by means of six methods and the average value was found to be equal to (76.10±1.10) kJmol−1 . The most suitable method for crystallization kinetic studies was the Augis–Bennett approximated method at different heating rates, while the method of Coats–Redfern–Sestak was the most suitable one at constant heating rate. The results have been discussed on the basis of theoretical principles.Primijenili smo diferencijalnu pretražnu kalorimetriju za proučavanje kinetike kristalizacije kalkogenidnog stakla Sb10Ge10Se80 u neizotermnim uvjetima. Odredili smo sljedeće parametre kristalizacije: parametar reda (n), faktor frekvencije (k0), aktivacijsku energiju kristalizacije (Ec), aktivacijsku energiju staklenog prijelaza (Eg) i aktivacijsku energiju nukleacije. Ec smo izveli na osnovi šest metoda i našli srednju vrijednost (76.10 ± 1.10) kJmol−1 . Najpogodnija metoda za proučavanje kinetike kristalizacije za različite brzine grijanja je Augis–Bennettova približna metoda, dok se metoda Coats–Redfern–Sestak-a pokazala najbolja za stalnu brzinu grijanja. Postignuti ishodi raspravljaju se na osnovi teorijskih postavki

Exciton-Polariton scattering for defect detection in cold atom Optical Lattices

We study the effect of defects in the Mott insulator phase of ultracold atoms in an optical lattice on the dynamics of resonant excitations. Defects, which can either be empty sites in a Mott insulator state with one atom per site or a singly occupied site for a filling factor two, change the dynamics of Frenkel excitons and cavity polaritons. While the vacancies in first case behave like hard sphere scatters for excitons, singly occupied sites in the latter case can lead to attractive or repulsive scattering potentials. We suggest cavity polaritons as observation tool of such defects, and show how the scattering can be controlled in changing the exciton-photon detuning. In the case of asymmetric optical lattice sites we present how the scattering effective potential can be detuned by the cavity photon polarization direction, with the possibility of a crossover from a repulsive into an attractive potential.Comment: 9 pages, 10 figure

Changes in Physico-Chemical Quality and Volatile Compounds of Orange-Carrot Juice Blends During storage

The present study aimed to determine the changes in physico-chemical parameters (pH, total soluble solids “TSS”, total acidity, vitamin C, total carotene, total phenolic and antioxidant activity) as well as sensory evaluation and volatile constituents of the orange juice samples mixed with carrot juice at ratios (1:3, 3:1 and 1:1). While, the polyphenol content was determined using Folin–Ciocalteu, antioxidant activity was measured using two in vitro assays 2,2'-diphenyl-1-picrylhydrazyl (DPPH0) and metal chelating assays. While, the acidity increased, total carotene and pH of the juice decreased during the storage period. There were no significant changes in total phenolics throughout the storage period at the three blending ratios. A slight increase in antioxidant capacity during the storage period had been observed. The headspace volatiles of fresh orange and carrot juices as well as fresh and stored blend juice with ratio (1:3) for 14 days at refrigerator were collected and subjected to Gas chromatography (GC) and Gas chromatography-Mass spectrometery (GC-MS) analysis. A total of 26 volatile compounds were identified in samples of fresh orange and carrot juices as well as fresh and stored blend including 7 alcohols, 4 aldehydes, 9 monoterpene hydrocarbon and 6 esters. Limonene was the one most abundant monoterpene, representing in orange, carrot, fresh and stored blend 47.38, 42.37, 39.24 and 37.25%, respectively. Keywords: Orange- carrot juice, Blend, Antioxidant, Volatile compound

True Integer Valued Autoregressive Model with Skellam Distribution

In the present article, we introduce a new true integer valued autoregressive model of order one TPDINAR(1) for data sets on Z and either positive or negative correlations based on the Poisson difference (Skellam) marginal distribution and using a random walk variable (It). Properties of the model are derived. We consider several methods for estimating the unknown parameters of the model, and their properties are discussed. Simulations are carried out for the performance of these estimators for illustrative purposes. Finally, the analysis of real life time series data is presented, and its performance is compared to two different INAR(1) models that may also be used over the observed data

Effect of tool offset and tilt angle on weld strength of butt joint friction stir welded specimens of AA2024 aluminum alloy welded to commercial pure cupper

The aim of the present work is to investigate the mechanical properties and microstructure of butt joints friction stir welded (FSW) of dissimilar material specimens welded with single pass .The material used is AA2024 aluminum alloy  5 mm thick and pure commercial copper   .20 mm Flat shoulder tool  6 mm Pin diameter with a rotational speed of 900 rpm and 25 mm/min feed  is used in this work ,the tool is tilted 2o to the Z axes of the machine. The welded specimens have been tensile tested at room temperature in order to analyze the mechanical properties with respect to the parent metals. The microstructure of the welded specimens has been studied by employing optical microscopy. Micro-hardness examination is also performed on the welded specimens. FSW specimens welded with flat shoulder tool  and 2o tilt angle showed higher ultimate stress  than the specimens welded with flat shoulder tool and zero tilt angle . Specimens welded with 1 mm pin offset showed higher strength than the specimens welded with 0.5 and 1.5 mm pin offset. Keywords: Friction stir welding, subsequent passes , mechanical propertie

Collective Electronic Excitation Coupling between Planar Optical Lattices using Ewald's Method

Using Ewald's summation method we investigate collective electronic excitations (excitons) of ultracold atoms in parallel planar optical lattices including long range interactions. The exciton dispersion relation can then be suitably rewritten and efficiently calculated for long range resonance dipole-dipole interactions. Such in-plane excitons resonantly couple for two identical optical lattices, with an energy transfer strength decreasing exponentially with the distance between the lattices. This allows a restriction of the transfer to neighboring planes and gives rise to excitons delocalized between the lattices. In general equivalent results will hold for any planar system containing lattice layers of optically active and dipolar materials.Comment: 6 pages, and 7 figure

Study on Quality of Pair Distribution Function for Direct Space Approach of Structure Investigation

Study of the structure characteristics of solid materials is a key for development of technological applications. Potential of direct space approach for structure determination and refinement using powder X-ray diffraction data depend on the quality of pair distribution function (PDF) plot. So, the effect of data collection conditions and diffractogram characteristics on the quality of PDF plot has been investigated in detail. In addition, errors and possible tolerance have been estimated. Some parameters affect only either the X-ray diffractogram or PDF plots and others affect both. Considering the errors and tolerance, direct space approach can be confidently used for structure refinement, where the error did not exceed 10.0 % for inter-atomic radial distance longer than » 2.0 ? and 5.0 % for longer than » 4.0 ?, which is accepted for structure refinement. As tolerance is considered, every time the value of the lattice parameter is changed to smaller or larger than the correct value (+ 8.0 %), it comes back to the initial correct one. Although, advanced synchrotron radiation shows better data, conventional source can be used successfully for structure investigation applying direct space approach

Monotonic solutions of functional integral and differential equations of fractional order

The existence of positive monotonic solutions, in the class of continuous functions, for some nonlinear quadratic integral equations have been studied by J. Banas. Here we are concerned with a singular quadratic functional integral equations. The existence of positive monotonic solutions $x \in L_1[0,1]$ will be proved. The fractional order nonlinear functional differential equation will be given as a special case