Background:
Antibiotics play an important role in the treatment of infections to the humans
and at the same time, irrational, frequent prescription of higher antibiotics, change in gene
composition of microorganisms are all the reasons behind the development and introduction of new
antibiotics against different microorganisms.
Objective:
In this project, an attempt has been made to synthesize some derivatives of diazenyl
containing phenyl styryl ketones and also their in vitro screening was conducted against Mycobacterium
tuberculosis, Escherichia coli, Klebsiella pneumonia, Bacillus subtilis, Staphylococcus aureus,
Aspergillus niger and Candida albicans.
Methods:
Ten molecules were synthesized which are diazenyl containing chalcones. 4-
aminoacetophenone was diazotised and piperidine was coupled with the formed diazonium chloride.
Further, the acetoxy group underwent Claisen-Schmidt condensation with differently substituted
aldehydes to form the final compounds- the chalcones. The proposed chemical structures
were confirmed by different spectroscopic techniques like FTIR, 1H NMR and Mass spectroscopy.
TLC was used to know that the reactants were exhausted and the formation of the product occurred.
Sharp melting point of the compounds concludes the purity.
Results:
The MIC of the compounds 3CP, 3DP, 3EP and 3GP is 20 times the MIC of the standard
fluconazole drug against Aspergillus niger. The compound 3GP is as equipotent as the standard
drug Pyrazinamide with MIC of 3.12 µg/ml against Mycobacterium tuberculosis.
Conclusion:
The results are quite promising which on further studies may lead to drug molecules
against different microorganisms. Especially, 3EP can be considered as a broad spectrum agent due
to its potent activity against different microorganisms like Staphylococcus aureus, Escherichia
coli, Klebsiella pneumonia and Candida albicans.
Process of joining different components by the application of external heat has resulted in induced stress on metals. Friction stir welding has been developed in order to avoid such residual stress development while joining. In this present work, aluminium alloy AA2024 plates were welded by using Friction stir welding process. The experiments were conducted for different combinations of parameters such as rotational speed, transverse speed and axial load. Welded joints developed were tested for mechanical and microstructure analysis. Mechanical joints developed have a maximum hardness of 147.6 hv in nugget zone and maximum tensile strength of 368.76 N/mm 2. Response surface analysis carried out has revealed that transverse speed and rotational speed has high impact on the hardness and tensile strength respectively. The grains at the nugget zone were very fine and uni-axed improving their tensile strength.
The AA6063 aluminium alloy has gained widespread use in manufacturing the light-weighted structures which requires a high strength to weight ratio, and it possesses an excellent corrosive resistance in T6 heat-treated (solution heat treated and artificially aged) condition. The process of friction stir welding (FSW) is an emerging joining process of solid state that does not melt and recast the material being welded, as opposed in various other fusion welding processes, which are extensively utilized for combining the structural alloys of aluminium. The process of connecting separate components with external heat has resulted in induced stress on metals. The stir welding using friction was introduced in order to reduce the formation in residual stress during the joining process. The aluminium alloy AA6063 plates were fused utilising the friction stir welding procedure in this study. The studies were carried out using various combinations of speed in rotary condition, speed in transverse condition, and stress in axial condition. The generated joints that are welded was analysed mechanically and microstructurally. The maximum hardness of the mechanical joints produced is 93.25 HV, and the maximum tensile strength is 286.15 N/mm2. According to the results of the response surface analysis, transverse and rotary velocities possess a notable impact in hardness and durability, respectively.
The joining of two material with different chemical composition was a major setback for conventional methods of metal joining. The results of this welding were showing considerably great improvement in the aspects of quality of weld, amount of heat generated, uniform distribution of material, refined microstructure, enhanced tribology, materials flowing pattern, good strength with reduced internal stresses. Optimized parameters were estimated by using Desirabilty approach and Response surface methodology. Optimum parameter combination for dissimilar material welding was observed to be 913.74 rpm, 45 mm/min and 8kN. The desirability values for dissimilar welding process were 0.912 respectively. The grain enhancements were decreased in the range of WC> WT> HAZ> Parent material. The wear rate of dissimilar AA2024 and AA2099 were superior as the wear value increases from 0 to 50μm in the nugget zone. The coefficient of friction value remains constant throughout the wear experiment ranges from 0.3 to 0.55. Steady state friction values of 3N to 5N is observed when sliding distance increases. The wear loss was measured by finding the difference between initial weight and final weight and found as in the range from 0.2283 g to 0.4866 g.
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