Equilibrium studies for trimethoprim adsorption on montmorillonite KSF

In this study, the adsorption of trimethoprim (TMP) on montmorillonite KSF was studied under different conditions (pH, ionic strength, temperature). The results indicate that a pH value of 5.04 is optimum value for the adsorption of TMP on KSF. The adsorption kinetics was interpreted using pseudo-first-order kinetic model, pseudo-second-order kinetic model and intraparticle diffusion model. The pseudo-second-order model provides the best correlation with the experimental data of KSF adsorption. The adsorption data could be fitted with Freundlich, Langmuir and Dubinin-Radushkevich equation to find the characteristic parameters of each model. It was found that linear form of Langmuir isotherm seems to produce a better model than linear form of Freundlich equation. From the Langmuir and Freundlich equation, the adsorption capacity values raised as the solution temperature decreased. From DR isotherm, it was also determined that the type of adsorption can be considered as ion-exchange mechanism. Determination of the thermodynamic parameters DeltaH(0), DeltaS(0) and DeltaG(0) showed that adsorption was spontaneous and exothermic in nature. It was also added that adsorption of TMP by KSF may involve physical adsorption.     

Microwave triggered metal enhanced chemiluminescence: Quantitative protein determination

We present a new technology that offers a faster alternative to the chemiluminescence-based detection that is used in protein assay platforms today. By combining the use of silver nanostructures with chemiluminescent species, a technique that our laboratories have recently shown can enhance the system photon flux over 50-fold, with the use of low-power microwave heating to additionally accelerate, in essence "trigger", chemiluminescence-based reactions, then both ultrafast and ultrabright chemiluminescence assays can be realized. In addition, the preferential heating of the nanostructures by microwaves affords for microwave triggered metal enhanced chemiluminescence (MT-MEC) to be localized in proximity to the silvered surfaces, alleviating unwanted emission from the distal solution. To demonstrate MT-MEC, we have constructed a model assay sensing platform on both silvered and glass surfaces, where comparison with the identical glass substrate-based assay serves to confirm the significant benefits of using silver nanostructures for metal-enhanced chemiluminescence. Our new model assay technology can detect femtomoles of biotinylated BSA in less than 2 min and can indeed be modified to both detect and quantify a great many other biomolecules as well. As compared to traditional western blot approaches, MT-MEC offers protein quantification, high-sensitivity detection combined with ultrafast assay times, i.e., <2 min.     

Fracture Toughness (Mode-I) of Para-Aramid/Phenolic Nano Preform Composites

The mode-I interlaminar toughness properties of nanostitched para-aramid/phenolic multiwall carbon nanotube composites were studied. The toughness strength of the stitched and stitched/nano composites demonstrated 40 fold and 38 fold (beam theory) increases compared to the base composites, respectively. It was found that stitching yarn type, especially prepreg para-aramid stitching yarn, was effective. On the other hand, the initiation and propagation of the G_IC values for stitched and stitched/nano composites were considerably deviated due to strengthening mechanism of the para-aramid stitch yarn in the transverse direction of the composite. The fracture toughness resistance to arrest crack propagation in the stitched/nano composite was mainly due to through-the-thickness stitching fiber bridging and pull-out, and was also due to warp and weft directional fiber bridging and multiwall carbon nanotubes. The results demonstrated that mainly stitching and some extent the nanotubes arrested the crack growth. Therefore, the stitched/nano and especially stitched para-aramid/phenolic composites showed a better damage resistance performance.     

Modeling transient magnetohydrodynamic peristaltic pumping of electroconductive viscoelastic fluids through a deformable curved channel

A mathematical model is presented to analyze the unsteady peristaltic flow of magnetized viscoelastic fluids through a deformable curved channel. The study simulates the bio-inspired pumping of electroconductive rheological polymers which possess both electroconductive and viscoelastic properties. The Jeffrey viscoelastic model is utilized which features both relaxation and retardation terms of relevance to real polymers. A magnetic body force is incorporated for the influence of static radial magnetic field. The mass and momentum conservation equations are formulated in an intrinsic coordinate system and transformed with appropriate variables into a nondimensional system between the wave and the laboratory frames, under lubrication (i.e., low Reynolds number and long wavelength) approximations. Kinematic and no-slip boundary conditions are imposed at the channel walls. A magnetic body force is incorporated for the influence of static radial magnetic field in the primary momentum equation. An analytic approach is employed to determine closed-form solutions for stream function, axial pressure gradient, and volumetric flow rate. Spatiotemporal plots for pressure distribution along the channel (passage) length are presented to study the influences of curvature parameter, relaxation-to-retardation time ratio (Jeffrey first viscoelastic parameter) and Hartmann number (magnetic field parameter). The effects of these parameters on radial velocity distributions are also visualized. Cases of trapping and reflux in a curved channel are discussed. Streamline distributions are included to study trapping phenomena and to investigate more closely the impact of curvature, magnetic field, and viscoelastic properties on bolus evolution. The reflux or retrograde motion of the particles is studied by particle advection based on Lagrangian viewpoint. The simulations provide new insight into the mechanisms of pumping of electroconductive non-Newtonian liquids in realistic geometries.     

Extraction and detection of DNA from Bacillus anthracis spores and the vegetative cells within 1 min

The use of a combination of low-cost technologies to both extract and detect anthrax DNA from spores and vegetative cells in two steps within 1 min is described. In a cavity, microwave energy is highly focused using thin-film aluminum "bow-tie" structures, to extract DNA from whole spores within 20 s. The detection of the released DNA, from less than 1000 vegetative cells, without additional preprocessing steps is accomplished in an additional 30 s by employing the microwave-accelerated metal-enhanced fluorescence technique. The new platform technology presented here is a highly attractive alternative method for DNA extraction and the fast detection of gram-positive bacteria and potentially other pathogenic species and cells as well.     

Correlations for estimation of daily global solar radiation with hours of bright sunshine in Turkey

In this study, seven different empirical equations are employed to estimate the monthly average daily global solar radiation on a horizontal surface for provinces in the different regions of Turkey, using only the relative duration of sunshine. Daily global solar radiation and sunshine measurement data collected for the provinces of Turkey are obtained from the Turkish State Meteorological Service. The regression constants of the new models developed in this study are found for the provinces of Turkey, as well as that of some models given in the literature. In order to indicate the performance of the models, the statistical test methods of the mean bias error (MBE), mean absolute bias error (MABE), mean relative error (MRE), root mean square error (RMSE) and correlation coefficient (r) are used.     

The investigation of groove geometry effect on heat transfer for internally grooved tubes

An experimental study of surface heat transfer and friction characteristics of a fully developed turbulent air flow in different grooved tubes is reported. Tests were performed for Reynolds number range 10,000–38,000 and for different geometric groove shapes (circular, trapezoidal and rectangular). The ratio of tube length-to-diameter is 33. Among the grooved tubes, heat transfer enhancement is obtained up to 63% for circular groove, 58% for trapezoidal groove and 47% for rectangular groove, in comparison with the smooth tube at the highest Reynolds number (Re = 38,000). Correlations of heat transfer and friction coefficient were obtained for different grooved tubes. In evaluation of thermal performance, it is seen that the grooved tubes are thermodynamically advantageous (Ns, a < 1) up to Re = 30,000 for circular and trapezoidal grooves and up to Re = 28,000 for rectangular grooves. It is observed that there is an optimum value of the entropy generation number at about Re = 17,000 for all investigated grooves.     

Power flattening in the fuel bundle of a CANDU reactor

The strong non-uniformity of the fission power production density in the CANDU fuel bundle could have been mitigated to a great degree. A satisfactory power flattening has been achieved through an appropriately evaluated method by varying the composition of the LWR spent fuel/ThO₂ mixture in a CANDU fuel bundle in radial direction and keeping fuel rod dimensions unchanged. This will help also to greatly simplify fuel rod fabrication and allow a higher degree of quality assurance standardization.Three different bundle fuel charges are investigated: (1) the reference case, uniformly fueled with natural UO₂, (2) a bundle uniformly fueled with LWR spent fuel, and (3) a bundle fueled with variable mixed fuel composition in radial direction leading to a flat power profile (100% LWR spent fuel in the central rod, 80% LWR + 20% ThO₂ in the second row, 60% LWR + 40% ThO₂ in the third row and finally 40% LWR + 60% ThO₂ in the peripheral fourth row).Burn-up grades for these three different bundle types are calculated as 7700, 27,300, and 10,000 MW.D/MT until reaching a lowest bundle criticality limit of k_∞ = 1.06. The corresponding plant operation periods are 170, 660, and 240 days, respectively.     

Effects of hydrogenation of fossil fuels with hydrogen and hydroxy gas on performance and emissions of internal combustion engines

Energy security is an important consideration for development of future transport fuels. Among the all gaseous fuels hydrogen or hydroxy (HHO) gas is considered to be one of the clean alternative fuels. Hydrogen is very flammable gas and storing and transporting of hydrogen gas safely is very difficult. Today, vehicles using pure hydrogen as fuel require stations with compressed or liquefied hydrogen stocks at high pressures from hydrogen production centres established with large investments.Different electrode design and different electrolytes have been tested to find the best electrode design and electrolyte for higher amount of HHO production using same electric energy. HHO is used as an additional fuel without storage tanks in the four strokes, 4-cylinder compression ignition engine and two-stroke, one-cylinder spark ignition engine without any structural changes. Later, previously developed commercially available dry cell HHO reactor used as a fuel additive to neat diesel fuel and biodiesel fuel mixtures. HHO gas is used to hydrogenate the compressed natural gas (CNG) and different amounts of HHO-CNG fuel mixtures are used in a pilot injection CI engine. Pure diesel fuel and diesel fuel + biodiesel mixtures with different volumetric flow rates are also used as pilot injection fuel in the test engine. The effects of HHO enrichment on engine performance and emissions in compression-ignition and spark-ignition engines have been examined in detail. It is found from the experiments that plate type reactor with NaOH produced more HHO gas with the same amount of catalyst and electric energy. All experimental results from Gasoline and Diesel Engines show that performance and exhaust emission values have improved with hydroxy gas addition to the fossil fuels except NO_x exhaust emissions. The maximum average improvements in terms of performance and emissions of the gasoline and the diesel engine are both graphically and numerically expressed in results and discussions. The maximum average improvements obtained for brake power, brake torque and BSFC values of the gasoline engine were 27%, 32.4% and 16.3%, respectively. Furthermore, maximum improvements in performance data obtained with the use of HHO enriched biodiesel fuel mixture in diesel engine were 8.31% for brake power, 7.1% for brake torque and 10% for BSFC.     

Differential transform solution for Hall and ion‐slip effects on radiative‐convective Casson flow from a stretching sheet with convective heating

Magnetohydrodynamic (MHD) materials processing is becoming increasingly popular in the 21st century as it offers significant advantages over conventional systems, including improved manipulation of working fluids, reduction in wear, and enhanced sustainability. Motivated by these developments, the present work develops a mathematical model for Hall and ion‐slip effects on non‐Newtonian Casson fluid dynamics and heat transfer toward a stretching sheet with a convective heating boundary condition under a transverse magnetic field. The governing conservation equations for mass, linear momentum, and thermal (energy) are simplified with the aid of similarity variables and Ohm's law. The emerging nonlinear‐coupled ordinary differential equations are solved with an analytical technique known as the differential transform method. The impact of different emerging parameters is presented and discussed with the help of graphs and tables. Generally, aqueous electroconductive polymers are considered, for which a Prandtl number of 6.2 is employed. With increasing Hall parameter and ion‐slip parameter, the flow is accelerated, whereas it is decelerated with greater magnetic parameter and rheological (Casson) fluid parameter. Skin friction is also decreased with greater magnetic field effect, whereas it is increased with stronger Hall parameter and ion‐slip parameter values.