The Influences of Nb2O5, MnO2, CuO and B2O3 Addition on the Magnetic Properties of BaFe12O19 Magnets

In the present study, we have investigated the influence of different types of doping elements on magnetic properties of M-type BaFe₁₂O₁₉ samples. It was observed that Nb₂O₅ addition increases the coercive field, the remanence magnetization (M _r), and saturation magnetization (M _s) values by about 27 %, 47 %, and 53 %, respectively. In the same manner, MnO₂ also improves the magnetic parameters significantly. The M _r and M _s values show increments up to 40 % in magnitude. On the other hand, the best magnetic properties were achieved by the addition of CuO to the B₂O₃ doped BaFe₁₂O₁₉. These materials have M _r and M _s values up to ～34 emu/g and ～62 emu/g, respectively.     

Effects of cavity disinfectants on bond strength of an etch-and-rinse adhesive to water- or ethanol-saturated sound and caries-affected dentin

Objective: To evaluate the effect of cavity disinfectants on the immediate microtensile bond strength (μTBS) of an etch-and-rinse adhesive to water- and ethanol-saturated sound and caries-affected dentin (CAD). Material and Methods: Thirty-six human molars were sectioned to expose 1/3 of the mid-coronal dentin surface. Sound (n = 18) and CAD (n = 18) specimens were divided into six groups each (n = 3): one positive control (sound), one negative control (CAD), and five experimental groups each. In the control group, dentin surfaces were bonded using an etch-and-rinse adhesive with a traditional water-wet bonding technique. In the experimental groups, ozone was applied before etching and chlorhexidine after etching. In the ethanol-wet bonding groups, acid-etched dentin surfaces were treated with ethanol. Following adhesive application and composite buildups, bonded specimens were sectioned to form sticks. Failure modes were analyzed using a stereomicroscope. Results: The water-wet bonded sound control group yielded the highest μTBS among all groups (p < 0.001). The lowest μTBS values were observed in the ozone groups (p < 0.05). The ethanol-wet bonded CAD group exhibited a higher μTBS than the water-wet bonded negative controls. Although compared to the positive control, chlorhexidine decreased the μTBS (p < 0.05), an increase with no significant difference was observed in the negative control (p > 0.05). Conclusions: The μTBS values of CAD were lower than those of sound dentin. Ethanol-wet bonding improved the μTBS of CAD. Ozone application reduced the μTBS in both sound and CAD; chlorhexidine improved the immediate μTBS after etching in CAD.     

Improvement of Mechanical Properties of Reinforcing Steel Used in the Reinforced Concrete Structures

SAE1010 structural carbon steel, which has a low cost price and wide range of use in the construction industry, has been studied as dual phase (DP) steel subjected to appropriate heat treatment, and its mechanical properties have been investigated under various tempering conditions. Intercritical annealing heat treatment has been applied to the reinforcing steel in order to obtain DP steels with different martensite volume fraction. In addition, these DP steels have been tempered at 200, 300 and 400 °C for 45 min and then cooled to the room temperature. Mechanical properties such as tensile strength, yield strength, reduction in cross-sectional area, total elongation, resilience modulus and toughness have been examined. Furthermore, fractographic examination has been done with scanning electron microscope (SEM) as well as metallographic examination of the steels. As a result of this study, it is found that mechanical properties of DP steel have changed according to the hardness and ratio of martensite phase. In addition, tensile strength, yield strength and resilience modulus of the steels have been reduced. In contrast, the total elongation, reduction of the cross-sectional area and toughness have been increased.     

Copper(II) and zinc(II) biosorption on Pinus sylvestris L

The biosorption properties of copper(II) and zinc(II) onto a cone biomass of Pinus sylvestris L. was investigated by using batch techniques. The biosorption studies carried out with single metal solutions. The removal of copper(II) and zinc(II) from aqueous solution increased with pH and sharply decreased when pH of the solution was decreased. The maximum biosorption efficiency of P. sylvestris was 67% and 30% for Cu(II) and Zn(II), respectively. Batch kinetic and isotherm of biosorption metal ions were investigated. The second-order kinetic model was used to correlate the experimental data. The Freundlich and Langmuir model can describe the adsorption equilibrium of metal(II) on cone biomass. The biosorption constants were found from the Freundlich and Langmuir isotherms at 25 degrees C. It is found that the biosorption data of metals on cone biomass fitted both the Freundlich and Langmuir adsorption models.     

Energy and exergy analyses of space heating in buildings

In the present study, energy and exergy analyses are presented for the whole process of space heating in buildings. This study is based on a pre-design analysis tool, which has been produced during ongoing work for the International Energy Agency (IEA) formed within the Energy Conservation in Buildings and Community Systems Programme (ECBCSP) Annex 37. Throughout this paper, in all of the calculations such as heat losses and gains were taken according to Turkish Standards Institution TSE, which is in accordance with the European Standard TS EN ISO 13789. In the analysis, heating load is taken account but cooling load is neglected and the calculations presented here are done using steady state conditions. The analysis is applied to an office in Izmir with a volume of 720 m³ and a net floor area of 240 m² as an example of application. Indoor and exterior air temperatures are 20 °C and 0 °C, respectively. It is assumed that the office is heated by a liquid natural gas (LNG) fired conventional boiler, an LNG condensing boiler and an external air–air heat pump. With this study, energy and exergy flows are investigated. Energy and exergy losses in the whole system are quantified and illustrated. The highest efficiency values in terms of energy and exergy were found to be 80.9% for external air–air heat pump and 8.69% for LNG condensing boiler, respectively.     

Detection of Escherichia coli O157:H7 in ground beef using immunomagnetic separation and multiplex PCR

In the study 251 fresh ground beef samples sold in Ankara were analyzed to evaluate the prevalence of Escherichia coli O157:H7 by immunomagnetic separation (IMS) based cultivation technique. Virulence factors of the isolates were determined by multiplex PCR. Nineteen (7.6%) of 251 ground beef samples were found as contaminated with E. coli O157. By PCR analyse in two of the isolates fliC_h7 gene was detected and identified as E. coli O157:H7. According to the multiplex PCR one of the isolate has all stx₁, stx₂, eaeA, hly and fliC_h7 genes and the other has stx₁, eaeA, hly and fliC_h7 genes.     

Investigating 5-hydroxymethylfurfural formation kinetic and antioxidant activity in heat treated honey from different floral sources

The quality and biochemical properties of honey are affected by heating or during storage period. The most important biochemical reaction that occurs in this process is the Maillard reaction. HMF (5-hydroxymethylfurfural) is one of the major intermediate products in the Maillard reaction that can lead to quality reduction in heated honey. In this study, the effect of heating on the antioxidant activity, and colour values as Maillard reaction indicators of three different botanical honeys were investigated; the HMF formation was also determined. Temperatures of 50, 70 and 80 °C were applied on the honeys between 0 and 48 h. Total phenolic content, ferric reducing/antioxidant power and scavenging of 2,2-diphenyl-1-picrylhydrazyl free radical assays are used to determine the antioxidant capacity. Results showed that the formation of HMF and the antioxidant properties of honeys were significantly increased during the heating process. Pure HMF compound also showed lower antioxidant activity. The formation of HMF has higher degree of linearity in the fit of the zero order reaction and also it was the highest in the chestnut honey. Furthermore, it was found that as the biochemical value of the honeys increased, the HMF formation decelerated.     

Factors affecting environmental sustainability of urban renewal projects

Urban renewal programmes offer an opportunity to improve the environmental sustainability of urban areas by creating well-designed and well-constructed built environments. In this study, the contributions of built environment design elements to environmental sustainability were evaluated through a questionnaire survey with the participation of 323 people who previously worked in urban renewal projects. Implementing factor analysis, interrelated elements have been gathered under five factors: ‘transportation and accessibility’, ‘conservation of natural resources’, ‘built environment quality’, ‘supporting social life’ and ‘high-density usage’. To identify the importance weights of these factors, analytic hierarchy process (AHP) analysis was carried out with 40 academics and practitioners. Based on the results, ‘conservation of natural resources’ was found as the most important factor affecting the environmental sustainability of urban renewal projects. It is expected that the results of this study shall guide a wide range of urban renewal stakeholders, extending from designers to citizens, along the path of creating environmentally sustainable cities.     

Solar Cells with Enhanced Photocurrent Efficiencies Using Oligoaniline‐Crosslinked Au/CdS Nanoparticles Arrays on Electrodes

Different configurations of CdS nanoparticles (NPs) are linked to Au electrodes by electropolymerization of thioaniline‐functionalized CdS NPs onto thioaniline‐functionalized Au‐electrodes. In one configuration, thioaniline‐functionalized CdS NPs are electropolymerized in the presence of thioanline‐modified Au NPs to yield an oligoaniline‐crosslinked CdS/Au NPs array. The NP‐functionalized electrode generates a photocurrent with a quantum yield that corresponds to ca. 9%. The photocurrent intensities are controlled by the potential applied on the electrode, and the redox‐state of the oligoaniline bridge. In the oxidized quinoide state of the oligoaniline units, the bridges act as electron acceptors that trap the conduction‐band electrons that are transported to the electrode and lead to high quantum yield photocurrents. The reduced π‐donor oligoaniline bridges act as π‐donor sites that associate N,N′‐dimethyl‐4,4′‐bipyridinium, MV²⁺, by donor/acceptor interactions, K_a = 5270 M^?1. The associated MV²⁺ acts as an effective trap of the conduction‐band electrons, and in the presence of triethanolamine (TEOA) as an electron donor, high photocurrent values are measured (ca. 12% quantum yield). The electropolymerization of thioaniline‐functionalized Au NPs and thioaniline‐modified CdS NPs in the presence of MV²⁺ yields a MV²⁺‐imprinted NP array. The imprinted array exhibits enhanced affinities toward the association of MV²⁺ to the oligoaniline π‐donor sites, K_a = 2.29 × 10⁴ M^?1. This results in the effective trapping of the conduction‐band electrons and an enhanced quantum yield of the photocurrent, ca. 34%. The sacrificial electron donor, TEOA, was substituted with the reversible donor I₃^?. A solar cell consisting of the imprinted CdS/Au NPs array, with MV²⁺ and I₃^?, was constructed. The cell generated a photocurrent with a quantum yield of 4.7%.