Natural frequencies of a flat viaduct road part simply supported on two ends

Viaduct roads have wide application in big cities with high traffic loads, in order to decrease traffic density and to connect subways to highways. Viaduct roads are constructed using steel structures instead of concrete ones in areas of earthquake risks. The low weight of steel structures however causes problems such as vibration and noise. There is increasing demand especially in populated areas to suppress vibration and noise on highway roads for reducing noise-related environmental pollution. In this study, bending vibrations of rectangular plate viaduct roads, which are supported by six fixed elements of rectangular cross-sectional elements are considered. Natural frequencies are obtained using the Rayleigh-Ritz technique, finite elements analysis, experimentally and neural networks (NN).     

Real-time monitoring of flank wear behavior of ceramic cutting tool in turning hardened steels

Flank wear of an alumina-based ceramic cutting tool was determined in hard turning two workpieces (AISI 4340 and 52100 hardened steels) at three cutting speeds (142, 181, and 264?m/min) to devise a real-time monitoring system. Results of the six turning tests were assessed using Kruskal?CWallis test, regression models, and linear trend analysis. Multiple non-linear regression models that explained variation in flank wear as a function of time (second) had a range of $ R_{\rm{adj}}^2 $ values of 27.7% for the test 4340-142 to 95% for the test 52100-181. Linear trend models revealed that the highest flank wear rate of the ceramic cutting tool belonged to the test 52100-181. Interaction effect of the three cutting speeds and the two workpiece types was determined to account for 82.2% of variation in flank wear (P?<?0.001). The real-time monitoring system designed in this study appeared to be promising in terms of determining and quantifying flank wear behavior of the ceramic cutting tool and optimal hard turning conditions.     

Preparation of dye sensitized titanium oxide nanoparticles for solar cell applications

A new method for synthesis of titanium dioxide (TiO₂)-dye nanoparticles is reported. TiO₂ nanocrystals were obtained at 150 and 200 °C by using chemically bonded TiO₂-sensitizer dye as a precursor. Titanium tetraisopropoxide was first modified with a dye molecule and then precipitated by dropping into acidic water. A strongly colored precipitate was obtained. Hydrothermal growth of a colloidal solution was carried out in a Teflon-lined stainless steel autoclave. Dye sensitized solar cell efficiencies obtained were comparable and fill factor values were close to the analogous cells prepared by the use of conventional TiO₂ paste techniques. This method allows the use of different substrates together with nanocrystalline TiO₂ for many technological applications.     

The influence of operating and device parameters on the maximum efficiency and the maximum output power of thermoelectric generator

Thermoelectric power generators are one of the promising green energy sources. The operating and the generator parameters influence the generator output performance. In the present study, the influence of the operating and the generator parameters on the maximum output power and the efficiency of the thermoelectric power generator are examined. The output power corresponding to the maximum efficiency and the maximum attainable output power of the generator are compared. It is found that the maximum power of the thermoelectric generator corresponding to the high Figure of Merit is very sensitive to the operating temperature. The maximum power attainable is larger than that its counterpart corresponding to the maximum generator efficiency. Copyright © 2010 John Wiley & Sons, Ltd.     

Defining the suitability of new crushed rock aggregate source areas in the North of Kocaeli Province using GIS

This study evaluated the current crushed rock aggregate resources and defined the suitability of potential crushed rock aggregate resource areas in the north of Kocaeli Province by using the geographical information system (GIS). Evaluation of the current aggregate market showed that almost 80 % of the total annual production (14.35 million tonnes) is supplied by the quarries located in Gebze and 20 % of the total annual production (3.65 million tonnes) is supplied by the quarries located in Hereke. The commercial crushed rock aggregate is totally supplied from the limestone and dolomite type carbonate rocks in the northern Kocaeli region. Defining the suitability of potential crushed rock aggregate resource areas was achieved by using GIS methods. First, an aggregate bedrock potential map was developed by using the geological map of the area and categorized as high, moderate and low bedrock potential areas. The high potential areas, which comprised almost 25 % of the northern Kocaeli region, contain carbonate rocks with varying physical, chemical and engineering properties. Secondly, the suitability of the bedrock potential areas was checked by considering the land-use, distance to the county centres and distance to major roads and highways layers in the weighted overlay function of the GIS. The resulting final map contained not suitable, low suitability and suitable areas for crushed rock aggregate. The suitable areas were grouped into three zones according to their geographic distributions. Further, the most promising crushed rock aggregate areas were defined based on the previous field work and surveys in the suitable areas.     

The influence of nitrogen doping on reduced graphene oxide as highly cyclable Li-ion battery anode with enhanced performance

A straightforward, one-step route has been established to fabricate reduced- (rGO) and nitrogen-doped reduced graphene oxide (NrGO) with remarkable lithium-ion storage properties. The graphene oxide (GO) was synthesized as starting material by improved Hummers’ method. Thereafter, thermally annealing GO with NH₃ at elevated temperature to synthesize NrGO was yielded a more open structure with nitrogen sites suitable for enhanced Li intercalation. NrGO exhibited a reversible capacity of 240 mAhg^?1 at 10 Ag^-1 after 500 cycles with 90% capacity retention, which is the best result achieved among graphene oxide-based anodes at this current density. In contrast to rGO, NrGO cells exhibited a gradually increasing capacity profile, reaching up to 114% of the initial capacity at 0.1, 2, and 10 Ag^-1 current densities. Results showed that high occupancy of pyridinic N within NrGO enhanced battery performance and cell kinetics upon cycling which offers long-time operability at high current density.     

Transferrin-Decorated Niosomes with Integrated InP/ZnS Quantum Dots and Magnetic Iron Oxide Nanoparticles: Dual Targeting and Imaging of Glioma

The development of multifunctional nanoscale systems that can mediate efficient tumor targeting, together with high cellular internalization, is crucial for the diagnosis of glioma. The combination of imaging agents into one platform provides dual imaging and allows further surface modification with targeting ligands for specific glioma detection. Herein, transferrin (Tf)-decorated niosomes with integrated magnetic iron oxide nanoparticles (MIONs) and quantum dots (QDs) were formulated (PEGNIO/QDs/MIONs/Tf) for efficient imaging of glioma, supported by magnetic and active targeting. Transmission electron microscopy confirmed the complete co-encapsulation of MIONs and QDs in the niosomes. Flow cytometry analysis demonstrated enhanced cellular uptake of the niosomal formulation by glioma cells. In vitro imaging studies showed that PEGNIO/QDs/MIONs/Tf produces an obvious negative-contrast enhancement effect on glioma cells by magnetic resonance imaging (MRI) and also improved fluorescence intensity under fluorescence microscopy. This novel platform represents the first niosome-based system which combines magnetic nanoparticles and QDs, and has application potential in dual-targeted imaging of glioma.     

Selective separation of cobalt and nickel by flat sheet supported liquid membrane using Alamine 300 as carrier

Cobalt and nickel are among the most important nonferrous metals. The using of flat sheet supported liquid membranes (FSSLMs) to remove metals from wastewaters has been used actively by the scientific and industrial communities. In this study, the selective separation of cobalt from thiocyanate solutions containing cobalt and nickel by FSSLM was examined using tri-n-octylamine (Alamine 300) as carrier. The FSSLM was consisted of extractant, flat sheet support and organic solvent. The various parameters were studied to determine the optimum extraction and striping conditions of cobalt and nickel. These parameters were stirring speeds of phases, NH₄SCN concentration, pH, diluent type, extractant concentration, stripping reagent concentration and modifier concentration. Concentration of cobalt and nickel were determined by Shimadzu AA-6701GF spectrophotometer. In the optimum conditions, selective separation of cobalt was achieved with an efficiency of 98.4% within 8 h, for equimolar feed mixtures, 400 mg/L Co + 400 mg/L Ni, and the separation factor of Co(II) over Ni(II) was 234.4. In addition, for nonequimolar feed mixtures, 500 mg/L Co + 1000 mg/L Ni, Ni in excess, selective separation of cobalt was 99.9%, and the separation factor of Co was 506 in the same time.