Synthesis and optical characterization of ZnO nanoparticles capped with 2-aminothiols

ZnO nanoparticles were synthesized by precipitation method. To reduce the agglomeration among small ZnO nanoparticles, an efficient surface modification method was proposed using 2-aminothiols as a capping agent. The effect of capping reagent is investigated on optoelectronics properties of ZnO. The capping of ZnO with 2-aminothiol leads to the shift in fluorescence intensity and also effected the UV–vis spectra of ZnO. The strategy exposed new dimensions to fine tune the fluorescence signatures of the ZnO.     

Binuclear rhodium(III) and iridium(III) monoselenocarboxylates: Synthesis,spectroscopy and structure of an ortho-metallated iridium complex featuring an IrCCC(μ-Se) chelate ring

Monoselenocarboxylate–bridged binuclear complexes of Rh^III and Ir^III, [(Cp1MCl)₂(μ-SeCOAr)₂] (1) (M = Rh or Ir; Cp1 = pentamethylcyclopentadienyl; Ar = Ph, C₆H₄Me–4), have been isolated either by the reaction between [Cp1₂M₂(μ-Cl)₂Cl₂] with KSeCOAr in acetonitrile or by treatment of [Cp1MCl(solvent)₂][PF₆] with KSeCOAr in acetone. The novel binuclear complexes, [Cp1IrCl(μ-SeCOAr)(κ²-SeCOC₆H₃R–)IrCp1] (2) (R = H or Me-4) with ortho-metallation at one of the iridium centres have been isolated following the use of excess AgPF₆. The single crystal structure of [Cp1IrCl(μ-SeCOC₆H₅)(κ²-SeCOC₆H₄–)IrCp1] (2a) exhibits two phenylcarboselenolate moieties situated in syn fashion with respect to the “Ir₂Se₂” plane, one of which leans towards the metal centre in order to undergo ortho-metallation after iridium–chlorine bond dissociation.     

Vapor bubble dynamics and heat transfer characteristics over the spherical surface during saturated pool boiling

The present study deals with numerical investigations of the boiling phenomena over a spherical surface at different degrees of superheat (ΔT), varying from 10 to 500 K. Various phenomena like vapor sliding, bubble formation, pinch-off, induced vorticity have been illustrated for a deep understanding of the boiling process over a spherical surface. The effect of the degree of superheat on the bubble pinch-off time and volume is also investigated. Further, reported the spatial observation of vapor sliding and retention over the surface with time scale, overall and average characteristics. The fast Fourier transform of a spaced average void fraction of liquid and Nusselt number showed the dominance of film boiling with respect to the degree of superheat. As the degree of superheat increases, the vapor generation rate also increases, which produces a more vapor–liquid interface. Further, with an increase in the degree of superheat, the vapor generation progression shifted from linear to nonlinear patterns. A sphere with ΔT = 500 K generated 32.59 times more vapor than a sphere with ΔT = 10 K. It is found that the vapor generation is dependent on the degree of superheating and exposed time for heating. Thus, a correlation and artificial neural network model have been developed to predict vapor generation during boiling over the spherical surface as a function of time and degree of superheat.     

Silver-doped sol-gel borate glasses: Dose-dependent effect on Pseudomonas aeruginosa biofilms and keratinocyte function

Borate-based glasses have generated great interest for wound healing applications due to their ability to incorporate biologically therapeutic ions which can then be released at the site of repair attributable to their high dissolution rates. In this study, the anti-bacterial activity and cytocompatibility of sol-gel–derived silver-doped borate glasses (AgBGs) of the compositional range (60)B₂O₃–(36)CaO–(4–x)P₂O₅–(x)Ag₂O, where x = 0.0, 0.3, 0.5, and 1 (mol.%) were investigated, in vitro. The dose-dependent anti-bacterial activity of AgBGs was demonstrated against Pseudomonas aeruginosa under both planktonic conditions and pre-formed biofilms, with up to 99.7% reduction in bacterial cell counts. Lower concentrations of ionic dissolution products from AgBGs were non-toxic to keratinocytes, stimulating their growth and metabolic activity. Furthermore, compositions containing 0.3 and 0.5 mol.% Ag significantly accelerated the migration of keratinocytes at two different concentrations in an in vitro 2D wound healing model. In summary, these therapeutic AgBGs have demonstrated potential for accelerated wound healing.     

Electrical characterization of nanocrystalline SnSe and ZnSe thin films: effect of annealing

In this paper, experimental data on the electrical properties of as deposited and annealed nanocrystalline SnSe and ZnSe thin films are reported. The thin films of SnSe and ZnSe are deposited on glass substrate by chemical bath deposition method. The films are studied before and after thermal annealing at temperatures 473 K for 1 h. This annealing is done in vacuum of 2?×?10^?3 mbar. The various electrical parameters like dark conductivity, photoconductivity, activation energy, photosensitivity and carrier life time have been measured on these films before and after annealing.     

Elimination of overflow oscillations in digital filters employing saturation arithmetic

A criterion for the nonexistence of overflow oscillations in a class of digital filters employing saturation arithmetic is presented. The criterion is based on a novel characterization of the saturation nonlinearity (namely, the ‘reduced sector’ characterization) and, hence, is quite distinct from previously reported criteria.     

Slug flow in curved microreactors: Hydrodynamic study

The need for eco-friendly and energy saving processes which are substantially compact and give higher efficiency has led to the concept of process intensification (PI). Curved microchannel is such innovative device, which has potential for the intensification of processes currently carried out in conventional straight or T-type microchannels. Curved microchannels utilize the benefits of centrifugal force to its advantage. The present study deals with the numerical simulation of the Taylor flow in curved microchannels, particularly on gas and liquid slugs with varying curvature ratios (i.e., coil to tube diameter=5, 10, 20 and 30). The three-dimensional, unsteady slug flow development in the curved microchannel was carried out using control volume finite difference method (CVFDM). The gas and liquid slug lengths at various operating and fluid conditions were obtained. The slug flow development for different inlet conditions and geometries (premixed feed, T-type and Y-type inlets) was also studied in the curved microchannels. It was found that for low curvature ratio (D/d=3), the phenomenon of flow reversal and slug freezing takes place due to centrifugal and buoyancy forces. For the similar process conditions, with an increase in curvature ratio to 5 and 10, the phenomenon of flow reversal and slug freezing observed was very minor. The non-uniformity in the slug formation was observed for low curvature ratio as compared to the higher curvature ratios. Further the influence of surface tension, viscosity and wall adhesion was studied on slug flow development in the curved microchannels. From the results it was observed that the surface tension, viscosity and wall adhesion have significant influence on slug flow development in curved microchannels.     

An intelligent approach for the prediction of surface roughness in ball-end machining of polypropylene

Manufacturing paradigms over the last 150 years have changed from craft production, to mass production and now to mass customisation. One further extension of mass customisation is personalised manufacture, which is the concept of providing bespoke products to the individual consumer. As a result this has brought about the need for a greater degree of sophistication in manufacturing practises and the technologies employed. This bespoke form of manufacture of consumer goods is now being pursued on CNC machining centres as opposed to the alternative of highly expensive rapid prototyping methods. The problem with this form of manufacture is that the products are generally free formed objects which require sophisticated setups and machining. Ball-end machining is a method used to create cusp-type geometry, which is employed on CNC machines to create sculptured surfaces. The objective of this research is to provide a predictive model using a design of experiments strategy to obtain optimised machining parameters for a specific surface roughness in ball-end machining of polypropylene. This paper reports on new manufacturing knowledge to machine polypropylene using ball-end tooling in order to generate personalised sculptured surface products.     

Adsorptive desulfurization by activated alumina

This study reports usage of commercial grade activated alumina (aluminum oxide) as adsorbent for the removal of sulfur from model oil (dibenthiophene (DBT) dissolved in n-hexane). Bulk density of alumina was found to be 1177.77 kg/m³. The BET surface area of alumina was found to decrease from 143.6 to 66.4 m²/g after the loading of DBT at optimum conditions. The carbon-oxygen functional groups present on the surface of alumina were found to be effective in the adsorption of DBT onto alumina. Optimum adsorbent dose was found to be 20 g/l. The adsorption of DBT on alumina was found to be gradual process, and quasi-equilibrium reached in 24 h. Langmuir isotherm best represented the equilibrium adsorption data. The heat of adsorption and change in entropy for DBT adsorption onto alumina was found to be 19.5 kJ/mol and 139.2 kJ/mol K, respectively.     

Application of fly ash on the growth performance and translocation of toxic heavy metals within Cajanus cajan L.: Implication for safe utilization of fly ash for agricultural production

The present study was undertaken to examine the influence of the application of fly ash (FA) into garden soil for Cajanus cajan L. cultivation and on accumulation and translocation of hazardous metals from FA to edible part. Numerous studies have been reported on the growth and yield of agricultural crops under FA stress; however, there is a dearth of studies recommending the safe utilization of fly ash for crop production. Pot experiments were conducted on C. cajan L., a widely cultivating legume in India for its highly nutritious seeds. C. cajan L. were grown in garden soil and amended with varying concentrations of FA in a weight/weight ratio (0%, 25%, 50% and 100%; w/w). Incorporation of fly ash from 25% to 100% in garden soil increases the levels of pH, particle density, porosity and water holding capacity from 3.47% to 26.39%, 3.98% to 26.14%, 37.50% to 147.92% and 163.16% to 318.42%, respectively, than the control while bulk density decrease respectively from 8.94% to 48.89%. Pot experiment found that accumulation and translocation of heavy metals in tested plant depends on the concentration of FA. Addition of FA at lower concentration (25%) had shown positive results in most of the studied parameters of growth and yield (14.23% than control). The experimental results confirmed that lower concentration of FA (25%) is safe for C. cajan cultivation, which not only enhanced the yield of C. cajan L. significantly but also ensured the translocation of heavy metals to edible parts within the critical limits.