Production of Afyon Kaymak with Traditional and Technological Methods

Afyon kaymak （milk cream） is traditional dairy product of Afyon city which is a junction of Middle Anatolia and West regions and famous with its thermal tourism and food. However, challenging production process led Afyon kaymak to lose its importance. Although buffalo milk is the raw material of traditional Afyon kaymak, cow milk can be used in the process. In traditional process, milk is filtered with double cheesecloth and gotten into the aluminum or tinned copper milk cream pans where the capacity is around 2.5-3.0 L. Half-filled pan is warm up to 90-95 ℃. Pans are carried to cool area and left until cooling. Milk cream on the cooled pans is lined by a pin. New milked milk is added to the lined cream in pans and heated for 1 h. It is covered and held on for 6-8 h. While holding period is until afternoon on summer time, it is until mid-afternoon in winter. Covers of the pans are opened and hold in a cool place until morning and, thus, cream is chilled. Cream layer on pans are lined and gotten out of pans. Cream as circle is divided into four pieces and left to the cream package after turning down. In this review, we aimed to give some information about Afyon kaymak and its production methods.     

Empirical model for the quantitative prediction of losses of radial fans based on CFD calculations

In a classical layout process of a fan the quantity of losses is estimated as a sum and expressed in the overall efficiency rate η. However the characteristic of the pressure rise, the losses and the efficiency rate beside the design point is not known. Against this background a numerical model was developed to calculate quantitative values of occurring losses at radial fan impellers at an early stage in the design process. It allows to estimate the pressure rise and efficiency rate of a given fan geometry at and beside the design point. The physics of losses are described in literature, but obtaining quantitative values is still a challenge. As common in hydraulic theory the losses are calculated with analytic formulas supported by coefficients and efficiency rates, which have to be determined empirically. This paper shows the method how to determine the coefficients for a given radial fan. Therefore a representative radial fan with backward curved blades was designed in reference to classical design guidelines. Performance measuring was done conform to ISO 5801. The flow was calculated at 8 different operation points using CFD methods. The RANS equations are solved by using the SST-k-omega turbulence model. The flow domain consists of one blade section including inlet channel and outflow chamber. Spatial discretization is done by a block-structured mesh of approx. 1.8 million cells. Performance data show a very good agreement between measurement and calculation.     

Biosensing Applications of Modified Core–Shell Magnetic Nanoparticles

Fe₃O₄ magnetic nanoparticles (MNPs) were synthesized and silanized to form a core–shell (Fe₃O₄–SiO₂) structure. Afterwards, surface modification with amino silane was carried out to produce amino groups on the MNPs for the biomolecule immobilization. In order to test the performance of amino functional MNPs as immobilization platform in biosensing applications, glucose oxidase was immobilized on the surface via glutaraldehyde. Obtained Bio-MNPs were then fixed onto the carbon paste electrode by the aid of magnetic force and used as the working electrode during the amperometric measurements at −0.7 V versus Ag/AgCl. After optimization of some parameters affecting the biosensor performance, analytical characterization was carried out. Linearity was found in the range of 0.25–2.0 mM glucose and defined by the equation of y = 8.366x + 1.819, (R ² = 0.996). Proposed biosensor was then applied for the glucose analysis in various beverages. Finally, data were compared with a commercial enzyme assay kit based on spectrophotometric Trinder reaction as a reference method.     

ZnO/p-Si heterojunction photodiode by sol–gel deposition of nanostructure n-ZnO film on p-Si substrate

The electrical and photovoltaic properties of the nanostructure ZnO/p-Si diode have been investigated. The nanostructure ZnO/p-Si diode was fabricated using sol–gel spin coating method. The ideality factor and barrier height of the diode were found to be 3.18 and 0.78 eV, respectively. The obtained n ideality factor is higher than 2, indicating that the diode exhibits a non-ideal behavior due to the oxide layer and the presence of surface states. The nanostructure of the ZnO improves the quality of ZnO/p-Si interface. The diode shows a photovoltaic behavior with a maximum open circuit voltage V_oc of 0.26 V and short-circuits current I_sc of 1.87×10^?8 A under 100 mW/cm². It is evaluated that the nanostructure ZnO/p-Si diode is a photodiode with the obtained electronic parameters.     

Sol-gel derived Li-Mg co-doped ZnO films: Preparation and characterization via XRD, XPS, FESEM

Li-Mg co-doped ZnO films have been deposited onto glass substrates by sol-gel spin coating method. The structural and morphological properties of the films were characterized by X-ray diffractometer (XRD), X-ray photo-electron spectroscopy (XPS) and field emission scanning electron microscopy (FESEM). The XRD spectra indicated that the films have polycrystalline nature. The crystallite size values decreased with the increasing Mg content. The chemical composition of the Li-Mg co-doped ZnO films were confirmed by XPS. Additionally, XPS results clearly showed the existence of Mg as a doping element into ZnO crystal lattice. The surface morphology of the films was found to depend on the concentration of Mg in the ZnO:Li. The absorption band edge values of the films were calculated and these values of the films increased with increasing Mg concentration. The refractive index dispersion curves of the films obeyed the single-oscillator model. The dispersion parameters such as E_o (single-oscillator energy) and E_d (dispersive energy) of the films were determined and increase with Mg content.     

Improved mobility of the copper phthalocyanine thin-film transistor

Copper phthalocyanine (CuPc) organic thin-film transistor (OTFT) was fabricated by thermal evaporation deposition on p-SiO₂ dielectric layer. Organic thin-film transistors used in large display areas need the enhancement of transistor performances by increasing the I_on/I_off ratio and the mobility. The output and transfer characteristics of CuPc-OTFT having source/drain interdigitated-finger geometry were investigated. The mobility, I_on/I_off ratio and inverse sub-threshold slope for the CuPc-OTFT were found to be 5.32 × 10^?3 cm² V^?1 s^?1, 1.94 × 10⁴ and 2.5 V/decade, respectively. The interface state density of the transistor was found to be 3.73 × 10¹¹ eV^?1 cm^?2 using the conductance-frequency method. The CuPc film indicated a homogeneous surface having 3.878 nm small roughness values as observed by atomic force microscope (AFM) measurements. The obtained results indicate that we have improved a CuPc-OTFT transistor with high mobility without being of any substrate treatment.     

On calibration and validation of eigendeformation-based multiscale models for failure analysis of heterogeneous systems

We present a new strategy for calibration and validation of hierarchical multiscale models based on computational homogenization. The proposed strategy hinges on the concept of the experimental simulator repository (SIMEX) which provides the basis for a generic algorithmic framework in calibration and validation of multiscale models. Gradient-based and genetic algorithms are incorporated into SIMEX framework to investigate the validity of these algorithms in multiscale model calibration. The strategy is implemented using the eigendeformation-based reduced order homogenization (EHM) model and integrated into a commercial finite element package (Abaqus). Ceramic- and polymer- matrix composite problems are analyzed to study the capabilities of the proposed calibration and validation framework.     

Laplace‐domain,high‐order homogenization for transient dynamic response of viscoelastic composites

This paper presents a high‐order homogenization model for wave propagation in viscoelastic composite structures. Asymptotic expansions with multiple spatial scales are employed to formulate the homogenization model. The proposed multiscale model operates in the Laplace domain allowing the representation of linear viscoelastic constitutive relationship using a proportionality law. The high‐order terms in the asymptotic expansion of response fields are included to reproduce micro‐heterogeneity‐induced wave dispersion and formation of bandgaps. The first and second‐order influence functions and the macroscopic deformation are evaluated using the finite element method with complex coefficients in the Laplace domain. The performance of the proposed model is assessed by investigating wave propagation characteristics in layered and particulate composites and verified against direct numerical simulations and analytical solutions. The analysis of dissipated energy revealed that material dispersion may contribute significantly to wave attenuation in dissipative composite materials. The wave dispersion characteristics are shown to be sensitive to microstructure morphology. Copyright © 2015 John Wiley & Sons, Ltd.