A Biphasic Model for Hip-Joint Replacement

The ball-and-socket geometry of the hip joint makes kinematic analysis of the joint motion relatively straightforward in comparison to other joints. The load-carrying surfaces of both ball and socket are covered with tough viscoelastic material known as cartilage. A number of lubrication theories have been proposed in the literature to account for the low coefficient of friction and low wear observed in healthy joints. The actual mechanism by which joints are capable of sustaining large repetitive loads with virtually no wear and with very little friction has not been fully understood. Therefore, analytical studies are presented for the understanding of the lubrication mechanism occurring in hip-joint replacements under restricted motion during standing or in the supporting phase during walking. The viscoelastic fluid has been considered to represent the synovial fluid in the fluid-film region. The problem described here has been analyzed in two regions (the porous matrix and the fluid-film region) separately along with suitable matching and boundary conditions at the interface. It has been concluded that the effect of the viscoelastic parameter for a particular gap is to increase the load capacity, indicating positive effects of the increase in concentration of suspended particles in the lubricant region. It has been observed that the coefficient of friction decreases with increasing values of the viscoelestic parameter. This is due to the fact that as the viscoelastic parameter increases, the concentration of hyaluronic acid molecules increases. It may also be noted from the results that the coefficient of friction decreases with increasing values of slip parameter. This shows that the slip velocity occurring at the porous boundary helps in maintaining normal functioning of human joints.     

Efficient photodegradation of methylene blue (MB) under solar radiation by ZrC nanoparticles

Due to increase in water pollution, there is a need to dwindle this problem for a clean and green future. Photocatalysts like ZnO, CaO and TiO₂ have proved to be triumphant in removal of environmental contaminants. In this present work, ZrC nanopowder has been synthesized using a single-step reduction technique by heating zirconium oxide (ZrO₂) and hexane (C₆H₁₄) in metallic Mg powder and is used as a photocatalyst for the degradation of methylene blue (MB) dye under solar radiation. Optimization of synthesis parameters (temperature, holding time and carbon content) has been done to obtain single phase ZrC. Various characterization techniques like X-ray diffraction (XRD), transmission electron microscope (TEM), differential scanning calorimetry/thermal gravimetric analysis (DSC/TGA) and X-ray photoelectron spectroscopy (XPS) were studied for various structural, thermal and surface characteristics of as-synthesized samples. The effect of synthesis parameters on crystal distortion of ZrC particles was studied with the help of Double Voigt analysis. Further, the comparative catalytic activity as photodegradation of MB dye with the help of optimized sample was studied under UV and solar radiations. As an effect of illumination source with the same concentration of catalyst and dye, 80% degradation was observed under solar radiations which is quite higher than that observed under UV in 5?h.     

Photocatalytic activities of hydrothermal synthesized copper zinc tin sulfide nanostructures

Journal of Materials Science: Materials in Electronics - We report the hydrothermal synthesis of visible light absorbing and direct energy bandgap kesterite-structured Cu2ZnSnS4 (CZTS)...     

Experimental investigation with optimal prediction of emission in diesel engine using combined NSR–SCR catalyzer

Clean Technologies and Environmental Policy - The utilization of catalytic converters is one of the well-known strategies to clean the exhaust. The catalytic converters oxidize the destructive...     

Reactivity of Hydroxamate Ions in Cationic Vesicular Media for the Cleavage of Carboxylate Esters

The hydrolysis of carboxylate esters viz. p‐nitrophenyl acetate (PNPA), p‐nitrophenyl butyrate (PNPB) and p‐nitrophenyl octanoate (PNPO) in the presence of cationic vesicles of the surfactant dioctadecyldimethylammonium bromide (DODAC) by different hydroxamate ions i.e. acetohydroxamate (AHA^?), benzohydroxamate (BHA^?) and salicylhydroxamate (SHA^?) were studied. The kinetic data was supported by spectrophotometric measurements. The effects of vesicular size on the reaction have been discussed. The differential reactivity under endo‐ and exovesicular conditions has also been evaluated. Critical vesicle concentrations (CVC) of cationic vesicular surfactants were determined from conductometric and fluorimetric measurements at 300 K. Fluorescence probe pyrene and pyrene‐1‐carboxaldehyde have been used for determination of CVC. Further, thermodynamic parameters viz. Standard Gibb's energy (?G°), enthalpy (?H°), and entropy (?S°) of vesicles has also been evaluated within a temperature range of 303.15–328.15 K.     

Novel analytical reagent for the application of cloud-point preconcentration and flame atomic absorption spectrometric determination of nickel in natural water samples

Cloud-point extraction was applied as a preconcentration of nickel after formation of complex with newly synthesized N-quino[8,7-b]azin-5-yl-2,3,5,6,8,9,11,12octahydrobenzo[b][1,4,7,10,13]pentaoxacyclopentadecin-15-yl-methanimine, and later determined by flame atomic absorption spectrometry (FAAS) using octyl phenoxy polyethoxy ethanol (Triton X-114) as surfactant. Nickel was complexed with N-quino[8,7-b]azin-5-yl-2,3,5,6,8,9,11,12octahydrobenzo[b][1,4,7,10,13]pentaoxacyclopentadecin-15-yl-methanimine in an aqueous phase and was kept for 15 min in a thermo-stated bath at 40 degrees C. Separation of the two phases was accomplished by centrifugation for 15 min at 4000 rpm. The chemical variables affecting the cloud-point extraction were evaluated, optimized and successfully applied to the nickel determination in various water samples. Under the optimized conditions, the preconcentration system of 100 ml sample permitted an enhancement factor of 50-fold. The detailed study of various interferences made the method more selective. The detection limits obtained under optimal condition was 0.042 ngml(-1). The extraction efficiency was investigated at different nickel concentrations (20-80 ngml(-1)) and good recoveries (99.05-99.93%) were obtained using present method. The proposed method has been applied successfully for the determination of nickel in various water samples and compared with reported method in terms of Student's t-test and variance ratio f-test which indicate the significance of present method over reported and spectrophotometric methods at 95% confidence level.     

Experimental study on thermal performance of optimum PG brine as a radiator coolant

The present study deals with the experimental impact of an alternative heat transfer fluids for overall performance improvement for radiators. Water and water mixed with anti‐freezing agents such as ethylene glycol (EG) and propylene glycol (PG) are the traditional coolants for an automotive radiator. Comparison of experimental and numerical analysis of optimum brine solution, that is 25% of propylene glycol and water as coolant for the rectangular fin radiator, has been well discussed. A closed loop test rig was designed, and fabricated with a wind tunnel section to achieve uniform velocity at the test section of the rectangular radiator and was tested for performance. Experimental runs were conducted at varying operating temperatures which included the runs for water, and an optimum propylene glycol brine solutions at 70 °C and 80 °C with various flow rates. Results show the energy performance of an optimum brine solution was nearly similar to that of water at high temperatures. The Nusselt number, heat transfer coefficient, and heat transfer rate for an optimum propylene glycol brine is nearly the same as water at 80 °C with a maximum deviation of 15%, 5.7%, and 6.6%, respectively, for theoretical and experimental result comparisons. Air side and coolant side pressure drops had a maximum deviation of 3.66% and 6.6%, respectively. Air and coolant exit temperatures had a deviation of 5% and 3.5%, respectively, with an air frontal velocity of 4.6 m/s in a rectangular fin radiator for an optimum brine solution used as coolant for the automotive radiator. The optimum propylene glycol brine may be environmentally beneficial.     

Single step low temperature synthesis of gadolinium gallium garnet nanopowders

Solution combustion synthesis of single-phase gadolinium gallium oxide(Gd3Ga5O12,GGG)nanopowders,by a fuel mixture approach using urea and glycine at a low temperature of 500oC,was being reported for the first time.Based on the fact that urea and glycine are good fuels for gallium oxide and gadolinium oxide synthesis,the fuel mixture composition was obtained,which could lead to direct phase pure cubic Gd3Ga5O12 formation without any subsequent calcination step.Combustion was carried out in furnace pre-heated at 500oC.Thermogravimetric analysis(TGA)of combustion product showed negligible mass loss indicating direct formation of GGG powder.Fourier transform infrared(FTIR)spectrum of combusted product showed peak characteristic of GGG in case of mixed fuel.X-ray diffraction(XRD)confirmed formation of phase pure GGG at 500°C in preheated furnace.Very fine,well dispersed nanometric particles of size range of 50-100 nm were obtained,being uniform and close to spherical morphology as observed by transmission electron microscope(TEM).     

Wafer scale imprint uniformity evaluated by LSPR spectroscopy: a high volume characterization method for nanometer scale structures

We exploit the localized surface-plasmon resonance (LSPR) of terahertz gold gammadion structures for wafer scale critical dimension metrology of nanostructures. The proposed characterization method, LSPR spectroscopy, is based on optical transmission measurements and is benchmarked against numerical simulations of imprinted structures characterized by atomic force microscopy. There is a fair agreement between the two methods and the simulations enable the translation of optical spectra to critical dimensions of the physical structures, a concept known from scatterometry. The results demonstrate the potential of LSPR spectroscopy as an alternative characterization method to scanning electron microscopy, atomic force microscopy and scatterometry.