Thermal and mechanical properties of La–Al–Sb alloys

We fabricated La–Al–Sb alloy by arc melter system and the fabrication conditions were described in detail. Microstructural analyses were performed and it was found that LaSb, Al₁₁La₃ Al₄La, AlLa₃ and Sb phases formed for different heat treatment conditions. The resistivity results showed the metallic and semiconducting type behavior depending on heat treatment temperatures. The thermal-conductivity measurement was performed in the range of 2–300 K and the data were analyzed by the sum of lattice and carrier components. The linear temperature dependence of thermo power indicates metallic type characteristic of the samples. The micro-hardness values of the phases in the samples were analyzed and it was found that there are two different hardness regions in the samples.     

Enhancement of convection heat-transfer in a rectangular duct

Characteristics of wall-to-air heat transfer for a fully developed forced convection have been studied in a large rectangular packed duct with 160 cm heated length, 40 cm width, and for low bed equivalent diameter to particle diameter ratio. The separation distance between the top and bottom walls is 10 cm. A uniform heat flux is supplied at the top wall, while the bottom wall is insulated. Raschig rings in two and spherical packing in three sizes have been used in the air flow passage to investigate the enhancement of heat transfer due to packing. Temperature profiles for the steady and unsteady states have been measured. In modeling, the Ergun equation and energy equations are solved to calculate the temperature profile for the steady-state only. It has been found that the introduction of the packing into the air flow passage increases the wall-to-fluid heat transfer approximately three times compared with that of empty bed. This finding can enhance the rational use of energy from solar air heaters, chemical reactors, electronic cooling and many other engineering applications.     

Transport of a soft cargo on a nanoscale ratchet

Surface ratchets can guide droplet transport for microfluidic systems. Here, we demonstrated the actuation of microgels encapsulated in droplets using a unidirectional nanotextured surface, which moves droplets with low vibration amplitudes by a ratcheting mechanism. The nanofilm carries droplets along the ratchets with minimal drop shape deformation to move the encapsulated soft cargo, i.e., microscale hydrogels. The tilted nanorods of the nanofilm produce unidirectional wetting, thereby enabling droplet motion in a single direction. Maximum droplet translation speed on the nanofilm was determined to be 3.5 mm∕s, which offers a pathway towards high throughput microgel assembly applications to build complex constructs.     

A real options evaluation model for the diffusion prospects of new renewable power generation technologies

This study presents a policy planning model that integrates learning curve information on renewable power generation technologies into a dynamic programming formulation featuring real options analysis. The model recursively evaluates a set of investment alternatives on a year-by-year basis, thereby taking into account that the flexibility to delay an irreversible investment expenditure can profoundly affect the diffusion prospects of renewable power generation technologies. Price uncertainty is introduced through stochastic processes for the average wholesale price of electricity and for input fuel prices. Demand for electricity is assumed to be increasingly price-sensitive, as the electricity market deregulation proceeds, reflecting new options of consumers to react to electricity price changes (such as time-of-use pricing, unbundled electricity services, and choice of supplier). The empirical analysis is based on data for the Turkish electricity supply industry. Apart from general implications for policy-making, it provides some interesting insights about the impact of uncertainty and technical change on the diffusion of various emerging renewable energy technologies.     

Thermodynamically coupled heat and mass flows in a reaction-transport system with external resistances

Considerable work has been published on mathematically coupled nonlinear differential equations by neglecting thermodynamic coupling between heat and mass flows in reaction-transport systems. The thermodynamic coupling refers that a flow occurs without or against its primary thermodynamic driving force, which may be a gradient of temperature, or chemical potential, or reaction affinity. This study presents the modeling of thermodynamically coupled heat and mass flows of two components in a reaction-transport system with external heat and mass transfer resistances. The modeling equations are based on the linear nonequilibrium thermodynamics approach by assuming that the system is in the vicinity of global equilibrium. The modeling equations lead to unique definitions of thermodynamic coupling (cross) coefficients between heat and mass flows in terms of kinetic parameters and transport coefficients. These newly defined parameters need to be determined to describe coupled reaction-transport systems. Some representative numerical solutions obtained by MATLAB illustrate the effect of thermodynamic coupling coefficients on the change of temperature and mass concentrations in time and space.     

Primary closure of gunshot wounds caused by high-velocity rifles

Sixty gunshot injuries in 48 patients were treated in Mobile Surgical Hospital (30-bed capacity) of the Mountain and Commando Brigade in Hakkari, Türkiye, between May 1990 and May 1991. The David Sisk method was used for the classification of the injuries. Eleven type 1 injuries were treated conservatively, 39 type 2 and 10 type 3 injuries were treated by extensive debridement with suction drainage and primary closure. No infection was seen in type 1 injuries. The infection rate was 2.56% in type 2 and 20% in type 3 injuries. The following results were obtained: type 1 injuries must be treated by conservative measures; type 2 injuries must be treated by primary closure following extensive debridement and suction drainage; type 3 injuries can be treated by extensive debridement with suction drainage and primary closure.     

Anaerobic acidogenesis of dairy wastewater: the effects of variations in hydraulic retention time with no pH control

The performance of a laboratory‐scale mesophilic acidogenic reactor was evaluated in this study, in terms of volatile fatty acid production and distribution, with respect to variations in hydraulic retention time (HRT). The continuous flow‐completely mixed anaerobic reactor, coupled with a conventional gravity settling tank and a continuous recycling system, was operated in a hydraulic retention time ranging between 24 and 12 h, and up to an organic loading rate of about 9.3 kg COD m^?3 d^?1, without pH control. The acid production gradually increased proportionally to the organic loading rate, with decrease in hydraulic retention time. The highest degree of acidification and the rate of acid production were 56% and 3.1 g dm^?3 d^?1 at 12 h of HRT. Variations in hydraulic retention time affected volatile fatty acid production and distribution substantially, for the range investigated. Acetic, propionic, butyric and valeric acids were commonly produced during acidogenesis of dairy wastewater. Copyright © 2004 Society of Chemical Industry