Thermoelectric Generators Using p-Pb0.925Yb0.075Te:Te and n-Pb0.925Yb0.075Se0.2Te0.8 Thin Films Prepared by the Thermal Evaporation Method

In this study, p-Pb_0.925Yb_0.075Te:Te and n-Pb_0.925Yb_0.075Se_0.2Te_0.8 ingots were used in a standard solid-state microwave synthesis route for fabricating thermally evaporated thin films. The nanostructure and composition of the films were studied through x-ray diffraction, field-emission scanning electron microscopy, and energy-dispersive x-ray spectroscopy. Measurements of the Seebeck coefficient and electrical conductivity were performed at 298 K to 523 K. The microthermoelectric devices were composed of 20 pairs and 10 pairs of p-Pb_0.925Yb_0.075Te:Te and n-Pb_0.925Yb_0.075Se_0.2Te_0.8 thin films on glass substrates, respectively. The 20-pair p–n thermocouples in series generated a maximum output open-circuit voltage of 275.3 mV and a maximum output power of 54.37 nW at a temperature difference ΔT = 162 K, and 109.4 mV and 16.68 nW at ΔT = 162 K for 10 pairs, respectively.     

Effect of the fatigue data editing technique associated with finite element analysis on the component fatigue design period

The present study concerns development of accelerated fatigue design time based finite element analysis (FEA) through a combination of the fatigue data editing (FDE) technique and FEA. Country road, pavement and highway fatigue data histories were collected using a fatigue data acquisition system. The component durability was evaluated using both original and editing fatigue data signals. Both signals showed a large difference in the CPU time. Furthermore, the histories were successfully edited by presenting the predicted amount of the fatigue damage as the original histories. As a consequence of application for automotive lower suspension arm, this technique can be applied in performing a fatigue history editing, especially in compression of data set. Briefly, design time was saved based on FDE technique associated with FEA.     

MHD natural convection inside an inclined trapezoidal porous enclosure with internal heat generation or absorption subjected to isoflux heating

A steady laminar two‐dimensional magneto‐hydrodynamic natural convection flow in an inclined trapezoidal enclosure filled with a fluid‐saturated porous medium is investigated numerically using a finite difference method. The left and right vertical sidewalls of the trapezoidal enclosure are maintained at a cold temperature. The horizontal top wall is considered adiabatic while the bottom wall is subjected to isoflux heating. A volumetric internal heat generation or absorption is embedded inside the trapezoidal enclosure while an external magnetic field is applied on the left sidewall of the enclosure. In the current work, the following parametric ranges of the non‐dimensional groups are used: Hartmann number is varied as , Darcy number is taken as , 10^?4, and 8 × 10^?5, Rayleigh number is varied as , Prandtl number is considered constant at Pr = 0.7, the dimensionless internal heat generation or absorption parameter is varied as Δ = ?0.2, 0, 1, and 2.0, while the trapezoidal enclosure inclination angle is varied as . The results indicated a strong flow circulation occurs when the Darcy and the Rayleigh numbers are high. In addition, it is found that the Hartmann number, internal heat generation or absorption parameter and inclination angle have an important role on the flow and thermal characteristics. It is also found that when the enclosure inclination angle and Hartmann number increase the average Nusselt number along the hot bottom wall decreases. © 2012 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21013     

Effects of diameter ratio of adiabatic circular cylinder and tilt angle on natural convection from a square open tilted cavity

A numerical analysis is carried out to study the performance of natural convection inside a square open tilted cavity filled with air. An adiabatic circular solid cylinder is placed at the center of the cavity and the sidewall in front of the breathing space is heated by a constant heat flux. The top and bottom walls are kept at the ambient constant temperature. Two‐dimensional forms of Navier–Stokes equations along with the energy equations are solved using the Galerkin finite element method. Results are obtained for a range of Grashof numbers from 10³ to 10⁶ at Pr = 0.71 while the tilt angle varies from 0 to 45° and the diameter ratio of the cylinder is considered to be 0.2, 0.3, and 0.4 with constant physical properties. The parametric studies for a wide range of cylinder diameter ratios and cavity tilt angles show significant features of the present problem in terms of stream functions and temperature profiles. The computational results indicate that the heat transfer coefficient is strongly influenced by the above governing parameters. It is also found that the average Nusselt number decreases when the diameter ratio increases. © 2012 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21001     

New Dyes and Intermediates for Synthetic-polymer Fibres. 7,7-Dioxo-Benzo(K, /)thioxan-thene-3,4-dicarboxylic Acid Imides

The synthesis of benzo [k, l] thioxanthene-3,4-dicarbo-xylic acid-7,7-dioxide is described. Condensation of this heterocycle with amines, or oxidation of the corresponding imides of benzo [k, l] thioxanthene-3,4-dicarboxylic acid, affords a new range of dyes which colour synthetic-polymer fibres, especially polyester, in yellow shades of excellent fastness to light and sublimation.     

Outbreak of Escherichia coli 0157:H7 infections associated with consumption of beef donair

The Calgary Health Region identified an outbreak of Escherichia coli 0157:H7 infection in September 2004 following a fourfold increase in laboratory reports. Clinical isolates were indistinguishable by pulsed-field gel electrophoresis (PFGE), and the PFGE pattern was unique in North America. Most affected individuals reported beef donair consumption in 10-day food histories. We conducted a matched case-control study, inspected the implicated food premises, and conducted a traceback investigation of suspect ground beef to determine the source of the outbreak and implement prevention and control measures. A total of 43 laboratory-confirmed cases were identified, with symptom onsets between 8 September and 1 October 2004. Among 26 matched case-control pairs, consumption of beef donair from one of two locations of a local restaurant chain was the only statistically significant risk factor for infection (matched odds ratio undefined; P < 0.01). No samples of the implicated ground beef were available for microbiological testing. We identified several opportunities for time-temperature abuse and other factors that may have contributed to the serving of unsafe donair meat at the implicated restaurants. This outbreak highlighted gaps in food safety policy related to beef donair and similar products in Canada. Immediately following the outbreak, the Region implemented new safe food handling requirements and a Federal/Provincial/Territorial Working Group was established to make recommendations for national food safety policies specific to these products.     

Measuring the instability of AC arc discharges

A digital approach using a microprocessor has been developed to give accurate values for AC arc discharge instabilities. This case study is based on theoretically interpreting the instability of arcs in terms of an instability factor related to the deviation of instantaneous values of arc voltages from a predetermined average value. A simple AC atmospheric pressure low-power arc discharge simulation circuit is used and the microprocessor-based measurements applied were found to give accurate indications of instability factors at different arc gaps. This article describes the hardware and software aspects of the system, accounts for the results and provides final critical remarks.     

Chitosan: Application in tissue engineering and skin grafting

Tissue Engineering and skin grafting, an essential part of regenerative medicine is one of the fastest growing biomedical fields which could offer an important therapeutic strategy for management of hard to heal wounds. 2D and 3D polymeric scaffolds are prerequisites in this field to promote cell adhesion, proliferation and tissue regeneration. Convergence of technology and research has successfully unveiled unknown properties of Chitosan as a bioactive polymer. Natural abundance, cost effectiveness, biodegradability, biocompatibility and wound healing capabilities of chitosan and its derivatives has drawn the attention of many researchers for its use as an alternative for fabrication of a scaffold in tissue engineering and skin graft. However lower mechanical strength and solubility has limited its application in the biomedical field. It has been found that the derivatization and combination with other polymers can successfully overcome these limitations. This review focuses on the applicability of chitosan and its derivatives in combination with other polymers in tissue engineering and skin grafting along with the novel scaffold fabrication techniques. Studies so far have demonstrated the potential of chitosan and its derivative as a scaffold in the field of regenerative medicine. However, even if the promising results obtained from in-vitro and preclinical studies prove the efficacy of chitosan scaffolds it still has a long way to go to be used in clinical set ups.     

Numerical Simulation of Natural Convection in a Parallelogrammic Enclosure Containing Volumetric Heat Source with Non‐uniformly Heated Left Sidewall

The influence of the external Rayleigh number, inclination angle, and internal Rayleigh number on natural convection within an air‐filled parallelogrammic enclosure containing a volumetric source has been investigated numerically. The left sidewall of the enclosure is subjected to a non‐uniformly hot temperature and the right sidewall experiences a uniform cold temperature while the remaining top and bottom walls are kept adiabatic. The physical problems are represented mathematically by various sets of governing equations along with the corresponding boundary conditions. Buoyancy forces are taken into account during the analysis of the present investigation. By using the finite volume method, the dimensionless governing equations are discretized numerically based on a non‐uniform collocated grid system. Results are obtained for a wide range of external Rayleigh numbers varying from 10³ to 10⁶ with internal Rayleigh numbers varying from (0) to (10⁸) while the left sidewall from vertical is varied as 0, 30, –30, 60, and ?60^°, respectively. In the present study, the obtained results are presented in terms of streamlines, isotherms, and average Nusselt number along the hot and cold sidewalls. Two pairs of rotating vortices are observed due to the non‐uniform heating process while the shape of this rotating vortices is sensitive to the inclination angle. Furthermore, the flow field circulation and the average Nusselt number increase remarkably with the increase in the external Rayleigh number. The results of the present work are compared with other published results and give excellent agreement. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res, 43(6): 542–560, 2014; Published online 11 November 2013 in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.21096