Scale-up studies for stable,long-term indoor and outdoor production of hydrogen by immobilized Rhodobacter capsulatus

Photofermentative hydrogen production by immobilized Rhodobacter capsulatus YO3 was carried out in a novel photobioreactor in sequential batch mode under indoor and outdoor conditions. Long-term H₂ production was realized in a 1.4 L photobioreactor for 64 days using Rhodobacter capsulatus YO3 immobilized with 4% (w/v) agar on 5 mM sucrose and 4 mM glutamate. The highest hydrogen yield (19 mol H₂/mol sucrose) and hydrogen productivity (0.73 mmol H₂ L^?1 h^?1) were achieved indoors on 5 mM sucrose. The effect of initial sucrose concentration (5 mM, 10 mM, and 20 mM) on hydrogen production was also investigated. Sustained hydrogen production was carried out under natural, outdoor conditions as well. For the outdoor experiments, the highest hydrogen productivity and yield were obtained as 0.87 ± 0.06 mmol H₂ L^?1 h^?1 and 6.1 ± 0.2 mol H₂/mol sucrose, respectively on 10 mM sucrose. Furthermore, this system prevented sudden pH drops and fluctuations caused by the utilization of sucrose throughout the process. These results demonstrate that a proper immobilization setup can lead to long-term efficient and robust hydrogen production even under naturally varying conditions.     

Planning for the Unexpected: Barriers to Young People's Participation in Planning in Disadvantaged Communities

This paper discusses barriers to civic engagement of disadvantaged young people that we observed in the course of a child-friendly city project in Turkey. It also emphasizes the importance of being prepared to overcome such barriers, some of which were quite unexpected. Results show that many of the unexpected issues are the outcome of poverty, illiteracy, lack of ethics, inexperience of project managers, conflicting political interests and sense of insecurity. The paper concludes with suggestions for researchers and policy-makers on how to overcome such unforeseen barriers to child and youth participation in disadvantaged communities.     

Numerical analysis of spouted-bed hydrodynamics

Some of the basic concerns in the analysis of spouted-bed hydrodynamics are the flow pattern and the pressure field of the fluid and the spout shape. These are closely related with other design concerns such as spoutability, minimum spouting velocity and maximum spoutable bed depth. A computer program was developed in order to determine the flow pattern, pressure distribution in the fluid phase and the spout shape for a given operational condition. The computer program relies upon a two region model with a spout and annulus element for an axisymmetric bed. The paper presents some results for grain drying beds and compares them with the existing experimental data qualitatively.     

Real-time monitoring of railroad track tension using a fiber Bragg grating-based strain sensor

Railway and train security are very important in preventing service disruption and ensuring quality and safe journeys. Conventional gauges are used in laboratory environments for the strain measurement of rails used in railways. However, the use of these electrical sensors is not practical in long-distance railways. Instead, access to long distances is possible with fiber optic sensors. In this study, the strain of 49E1 type rail with R260 hardness and quality was calculated theoretically. These results were compared with an experimentally established fiber Bragg grating system. Moreover, a user-friendly interface was prepared for real-time monitoring of the system. Upon examining the results, the maximum deviation at a rate of 2.5% occurred in the strain measurement in the rail in response to force changes between 0 and 200 kN. A value of approximately 1.38?pm/µε was calculated between the wavelength/strain changes.     

Analysis of macro segregation in twin-roll cast aluminium strips via solidification curves

A porous NiO/yttria-stabilized zirconia (YSZ) anode substrate for zirconia-based tubular solid oxide fuel cells (SOFCs) was prepared by the gelcasting. The effect of the impregnation of SDC in the substrate was studied. Electrochemical impedance spectroscopy and I–V and I–P curves of the cells were measured. Scanning electron microscopy (SEM) was used to observe the microstructures. The results indicate that the performance of the cell can be significantly improved by incorporating the nano-structured SDC particles in the substrate. The peak power density of the cell is increased by about 60% and the area specific resistance (ASR) decreased by about 47% at 700 °C, compared with the unmodified cells. It is explained as the extended triple-phase boundary (TPB) in the anode substrate and the excellent electrocatalytic property of SDC. It is also found that the nano-scale SDC particles change a lot during the reduction of the anode substrate, and the morphology of the resultant SDC particles on the metal Ni is significantly different from that on the YSZ. After the long-term operation, the morphology of the SDC particles on the Ni changes again, but that on the YSZ keeps almost unchanged.     

Al–Ti–B grain refiners via powder metallurgy processing of Al/K2TiF6/KBF4 powder blends

The response to thermal exposure of ball-milled Al/K₂TiF₆/KBF₄ powder blends was investigated to explore the potential of PM processing for the manufacture of Al–Ti–B alloys. K₂TiF₆ starts to be reduced by aluminium as early as 220 °C when ball-milled Al/K₂TiF₆/KBF₄ powder blends are heated. The reaction of KBF₄ with aluminium follows soon after. The Ti and B thus produced are both solutionized in aluminium before precipitating out as Al₃Ti and TiB₂. All these reactions take place below the melting point of aluminium. The ball-milled Al/K₂TiF₆/KBF₄ powder blends heat treated at approximately 525 °C can be compacted to produce Al–Ti–B pellets with in situ formed Al₃Ti and TiB₂ particles. These pellets are shown to be adequate grain refiners for aluminium alloys.     

Construction of a choline biosensor through enzyme immobilization on a poly(2‐hydroxyethyl methacrylate)‐grafted Teflon film

An amperometric choline biosensor was constructed by immobilizing choline oxidase (ChO) on poly(2‐hydroxyethyl methacrylate) (PHEMA)‐grafted Teflon (polytetrafluoroethylene, PTFE) film. Grafting was achieved by γ irradiation. PHEMA‐grafted Teflon films were activated with epichlorohydrin or glutaraldehyde to achieve covalent immobilization of enzyme onto the film. To decrease the diffusional barrier caused by the enzyme‐immobilized film, the film was stretched directly on the electrode. The PHEMA‐grafted Teflon film, therefore, had to have appropriate mechanical properties. Glucose oxidase (GOD) was used in the determination of optimum immobilization conditions, then these were applied to ChO. With GOD, the effect of activation type and film position in electrode on enzyme activity was studied and the highest catalytic activity was obtained when the enzyme was immobilized using glutaraldehyde and the film was stretched over the electrode surface. Further studies revealed that the films activated with glutaraldehyde, immobilized in 2 mg/mL ChO concentration, and stretched directly on the electrode were suitable (specific activity, 0.427 ± 0.068 U mg^?1) for use in the choline biosensor. The linear working range of this biosensor was found to be 52–348 μM, with a 40 ± 5 μM minimum detection limit. The response of the sensor, however, decreased linearly upon repeated use. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Scheduling a single machine with multiple preventive maintenance activities and position-based deteriorations using genetic algorithms

In this paper, we study a single machine scheduling problem with deteriorating processing time of jobs and multiple preventive maintenances which reset deteriorated processing time to the original processing time. In this situation, we consider three kinds of problems whose performance measures are makespan, total completion time, and total weighted completion time. First, we formulate integer programming formulations, and using the formulations, one can find optimal solutions for small problems. Since these problems are known to be NP-hard and the size of real problem is very large, we propose a number of heuristics and design genetic algorithms for the problems. Finally, we conduct some computational experiments to evaluate the performance of the proposed algorithms.