The effect of powder preparation method on the artificial photosynthesis activities of neodymium doped titania powders

The effects of nanostructure on the artificial photosynthesis activities of undoped and Nd doped titania (TiO₂) powders prepared by three different chemical co-precipitation methods were investigated. Substitutional/interstitial N and S doping was observed in powders due to the presence of high concentrations of HNO₃ (NP) and H₂SO₄ (SP) in the powder preparation media, respectively. Nd, N and S doping caused anatase/rutile phase transformation inhibition and crystallite size reduction in the nanostructure. Light absorption was significantly enhanced by Nd doping and the residual SO₄^2?/NO_x species in the nanostructure. Photocatalytic hydrogen production activity of Nd doped NP powder was 4 times greater than undoped NP powder at 700 °C and had a high purity (CO:H₂ ratio～0.00). CO was determined to be the main product in photocatalytic CO₂ reduction. NP powders had the highest CO yields and Nd doping enhanced CO production. The powders with high crystallite sizes and rutile weight fractions had the highest artificial photosynthesis activities.     

The use of grape,pomegranate and rosehip seed flours in Turkish noodle (erişte) production

Eri?te is a traditional cereal product in Turkey, which resembles Asian noodles. Since it is a suitable product for enrichment, it was aimed in this study to utilize some fruit processing by‐products to enrich eri?te in terms of antioxidants and to determine the effect of enrichment on physical properties of eri?te. For that purpose, eri?te samples enriched with three different proportions (10, 20 and 30%) of grape, pomegranate and rosehip seed flours were compared with the control group in terms of antioxidant activity, color, cooking, textural and sensory properties to evaluate the effect of enrichment on eri?te quality. It was determined that addition of 10% grape, pomegranate and rosehip seed increased the antioxidant activity of eri?te by 8, 4 and 5.7 times, respectively, as compared with the control. Although the sensory analysis indicate that eri?te enriched with pomegranate seed were mostly liked, antioxidant activity was found lower than the others.

Practical applications

Using by products and wastes of foods like fruit seeds for enrichment is a promising alternative for utilization. Grape, pomegranate and rosehip seeds have very high antioxidant levels with natural antioxidants like proanthocyanidins, resveratrol, tocopherols etc; rich in dietary fiber, also unsaturated and essential fatty acids. For this purpose; cooking, textural, sensory, color and antioxidant properties of enriched samples were compared with traditional Turkish noodle.     

Tm-doped ZnO nanorods as a TCO for PV applications

In photovoltaic(PV) devices, a transparent conducting oxide(TCO) film is used as a transparent electrode which permits sun rays to reach to the photoactive semiconducting layers and also to collect the photogenerated electrons. Due to their electrical and optical properties zinc oxide(ZnO) based thin films and nanostructures are considered as an abundant and safer option for TCOs. In this study, undoped and thulium(Tm)-doped ZnO nanorods(NRs) were produced on glass substrates via spin coating and hydrothermal methods. The ZnO samples were described by X-ray diffractometry(XRD). Morphological features of the ZnO samples were investigated with scanning electron microscopy(SEM). It is observed that the all ZnO samples have nanorod shape. The average rods diameter is between 75 and 100 nm. Also,the rods length is found to be between 0.96 and 1.62 μm. Electrical properties of the ZnO samples were performed via four probe method. The conductivity increases with measurement temperature and Tm doping. Optical spectra of the ZnO samples were measured in UV-Vis range and the band gap(E_g) is found to be 3.35 eV.     

A Novel Cardholder Behavior Model for Detecting Credit Card Fraud

Because credit card fraud costs the banking sector billions of dollars every year, decreasing the losses incurred from credit card fraud is an important driver for the sector and end-users. In this paper, we focus on analyzing cardholder spending behavior and propose a novel cardholder behavior model for detecting credit card fraud. The model is called the Cardholder Behavior Model (CBM). Two focus points are proposed and evaluated for CBMs. The first focus point is building the behavior model using single-card transactions versus multi-card transactions. As the second focus point, we introduce holiday seasons as spending periods that are different from the rest of the year. The CBM is fine-tuned by using a real credit card transaction data-set from a leading bank in Turkey, and the credit card fraud detection accuracy is evaluated with respect to the abovementioned two focus points.     

Influence of strain rate on tensile properties and fracture behaviour of DP600 and DP780 dual-phase steels

The influences of the strain rate on the tensile properties and fracture behaviour of DP600 and DP780 advanced high-strength sheet steels have been studied. The variation of their mechanical properties depending on the strain rate have been researched by applying uniaxial tensile tests at three different strain rates (0.001, 0.01, 0.06?s^?1). The influences of strain rate on fracture behaviour have been investigated by displaying the fracture surfaces of the material. Strain rate increase has been determined to increase the yield strength, tensile strength, total elongation and hardening rate. The strain hardening coefficient has been found not to be significantly affected by the strain rate. It has been determined that, the fracture has occurred faster during necking while load-carrying capacity has increased with strain rate increase.     

Optimal scheduling of booster disinfection in water distribution networks

Booster disinfection stations are the solution alternative to maintain required disinfectant residual concentration in water distribution networks. In the present study, an optimisation problem to determine the optimum injection rates is solved. The minimisation of the total injected mass is considered as the objective function which is subjected to bound constraints on chlorine concentration. Two formulations are used for the linear optimisation problem, with and without considering the initial concentrations as unknowns. Determination of variable network hydraulics and chlorine concentrations is achieved by EPANET. A C++ code was developed to interface with EPANET by means of the EPANET Programmer's Toolkit for optimisation of the disinfectant mass applied to the network. Finally, a cross check is achieved in EPANET software for both disinfectant residual concentrations and linear superposition principle.     

Entropy generation due to conjugate natural convection in enclosures bounded by vertical solid walls with different thicknesses

Entropy generation due to conjugate natural convection heat transfer and fluid flow has been studied inside an enclosure with bounded by two solid massive walls from vertical sides at different thicknesses. Enclosure is differentially heated from vertical walls and horizontal walls are adiabatic. Governing equations which are written in streamfunction-vorticity form solved by finite difference technique for the governing parameters as Rayleigh number, 10³ ≤ Ra ≤ 10⁶, length ratio of solid walls as ₁ (for left vertical wall) and ₂ (for right vertical wall) and thermal conductivity ratio of solid to fluid (k), 1 ≤ k ≤ 10. Entropy generation contours due to fluid friction and heat transfer irreversibility, isotherms, streamlines, Nusselt numbers and velocity profiles were obtained. It is found that entropy generation increases with increasing of thermal conductivity ratio and thicknesses of the walls. Entropy generation due to heat transfer is more significant than that of fluid flow irreversibility for all values of thickness of the solid vertical walls.