The effect of mechanical stirring on sol-gel synthesis of thorn-like ZnO nanoparticles (ZnO-NPs) and antimicrobial activities is successfully reported in this study. The in-house synthesized nanoparticles were characterized by XRD, SEM, TEM, FTIR, TGA, DSC and UV-visible spectroscopy. The X-Ray Diffraction analysis revealed the wurtzite crystal lattice for ZnO-NPs with no impurities present. The diametric measurements of the synthesized thorn-like ZnO-NPs (morphology assessed by SEM) were well accounted to be less than 50 nm with the help of TEM. Relative decrease in aspect ratio was observed on increasing the agitation speed. The UV-visible spectroscopy showed the absorption peaks of the ZnO-NPs existed in both UVA and UVB region. A hypsochromic shift in λmax was observed when stirring pace was increased from 500 rpm to 2000 rpm. The FTIR spectroscopy showed the absorption bands of the stretching modes of Zn-O between 500 cm−1 to 525 cm−1. The Thermal analysis studies revealed better stability for ZnO-NPs prepared at 2000 rpm (ZnO-2000 rpm). TGA revealed the weight loss between two main temperatures ranges viz. around (90 °C–120 °C) and (240 °C–280 °C). Finally, the effect of ZnO-NPs prepared at different stirring conditions on the growth of Gram-positive (Bacillus subtilis), Gram-negative (Escherichia coli) bacteria and a fungi (Candida albicans) were examined; which showed good antibacterial as well as antifungal properties. These findings introduce a simple, inexpensive process to synthesize ZnO-NPs using conventional methods without the use of sophisticated equipments and its application as a potent nano-antibiotic.

Due to enormous applications of metal oxide nanoparticles in research and health-related applications, metal oxide nanoparticles are increasingly being developed through cheaper and more user-friendly approaches. We have formulated a simple route to synthesize zinc oxide nanoparticles (ZNPs) by a sol–gel method at near-room temperatures 25°C, 35°C, 55°C, and 75°C. The results are analyzed by X-ray diffraction, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and ultraviolet-visible absorption spectroscopy. The effect of different temperature conditions (25°C–75°C) on the particulate sizes (23.7–88.8 nm), pH levels (11.7–11.9), and morphologies (slender needle–broad arrow) of flower-shaped ZNP colonies is studied. A possible mechanism depicting the growth rates at different temperatures and of different facets, mainly towards the <0 0 0 I> and <0 I Ī 0> planes of the ZNPs has also been discussed. The values of λ max (293–298 nm) suggest that ZNPs prepared at 55°C are the most effective ultraviolet B absorbers, and that they can be used in sunscreens. Highly significant antimicrobial activity against medically important Gram-positive ( Staphylococcus aureus ) and Gram-negative ( Escherichia coli ) bacteria and fungi ( Candida albicans ) by these ZNPs was also revealed. As S. aureus and C. albicans are responsible for many contagious dermal infections such as abscesses, furuncles, carbuncles, cellulitis, and candidiasis, we can postulate that our fabricated ZNPs may be useful as antimicrobial agents in antiseptic creams and lotions for the treatment of skin diseases.

Optimization of multi-criteria problems is a great need of producers to produce precision parts with low costs. Optimization of multi-performance characteristics is more complex compared to optimization of single-performance characteristics. The theory of grey system is a new technique for performing prediction, relational analysis, and decision making in many areas. In this paper, the use of grey relational analysis for optimizing the turning process parameters for the workpiece surface roughness and the chip thickness is introduced. Various turning parameters, such as cutting speed, feed rate, tool nose radius, and concentration of solid-liquid lubricants (minimumquantity lubricant) were considered. A factorial design with eight added center points was used for the experimental design. Optimal machining parameters were determined by the grey relational grade obtained from the grey relational analysis for multi-performance characteristics (the surface roughness and the chip thickness). The results of confirmation experiments reveal that grey relational analysis coupled with factorial design can effectively be used to obtain the optimal combination of turning parameters. Experimental results have shown that the surface roughness and the chip thickness in the turning process can be improved effectively through the new approach. The minimum surface roughness and smallest chip thickness are 9.83 and 0.32 mm, respectively, obtained at optimal conditions of cutting speed, 1,200 rpm; feed rate, 0.06 mm/rev; nose radius, 0.8 mm; and concentration of solid-liquid lubricant (10% boric acid + SAE-40 base oil).

Power consumption in turning EN-31 steel (a material that is most extensively used in automotive industry) with tungsten carbide tool under different cutting conditions was experimentally investigated. The experimental runs were planned according to 24+8 added centre point factorial design of experiments, replicated thrice. The data collected was statistically analyzed using Analysis of Variance technique and first order and second order power consumption prediction models were developed by using response surface methodology (RSM). It is concluded that second-order model is more accurate than the first-order model and fit well with the experimental data. The model can be used in the automotive industries for deciding the cutting parameters for minimum power consumption and hence maximum productivity. Turning is a very important machining process in which a single point cutting tool removes unwanted material from the surface of a rotating cylindrical work piece. The cutting tool is fed linearly in a direction parallel to the axis of rotation. Turning is carried on lathe that provides the power to turn the work piece at a given rotational speed and feed to the cutting tool at specified rate and depth of cut. Therefore three cutting parameters namely cutting speed, feed rate and depth of cut need to be optimized in a turning operation. Turning operation is one of the most important operations used for machine elements construction in manufacturing industries i.e. aerospace, automotive and shipping. Turning produces three cutting force components as shown in fig.1a,(the main cutting force i.e. thrust force, (F Z ), which acts in the cutting speed direction, feed force, (F X ), which acts in the feed rate direction and the radial force, (F Y ), which acts in radial direction and which is normal to the cutting speed). Out of three force components the cutting force (main force) constitutes about 70% to 80% of the total force 'F' and is used to calculate the power 'P' required to perform the machining operation [1,2,3].Power is the product of main cutting force and the cutting velocity and is a better criterion for design and selection of any machine tools. Power consumption may be used for monitoring the tool conditions. The objective of using response surface methodology (RSM) is not only to investigate the response over the entire factor space, but also to locate the region of intrest where the response reaches its optimum or near optimal values [4].It has long been recognized that, in order to optimize the economic performance of machining operations, reliable quantitative technological performance data and equations are required for the wide spectrum of machining operations, tools and work piece materials used in practice [4]. It has also been recognized that improving the technological performance measures such as the chip formation, forces, power, and tool life, improves the economic performance of machining operations as assessed by the time per component, cost per component or other suitable measures [...

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