Process forces and heat input as function of process parameters in AA5083 friction stir welds

AA5083 friction stir welds were produced using systematic experimental design, the process forces and heat input with varying parameters were studied. Helpful empirical models were developed in designing friction stir welding （FSW） tools and FSW welders. These models may be further helpful for making process parameter choice for this sort of alloy, defining welding program and control of process parameters by using computer numerical control friction stir welding welders. The results show that tool rotational speed, welding speed and tool shoulder diameter are most significant parameters affecting axial force and heat input, while longitudinal force is significantly affected by welding speed and probe diameter.

Direct detection of rpoB and katG gene mutations of Mycobacterium tuberculosis in clinical samples

To study the rpoB and katG gene mutation rate and its markers.MethodsCross-sectional study methods were used to study Tuberculosis. A total of 45 sputum samples were collected from Annapurna Neurological Institute and Allied sciences. Then, acid fast bacilli staining were performed. Positive and negative samples were carried for conventional polymerase chain reaction identification and electrophoresis.ResultsOut of 45 samples, 3 were acid fast bacilli positive and the rest were negative. Male participants were more as compare to female participants and the mutation in rpoB and katG gene was found similar i.e. 6.66% among the total samples.ConclusionsWe can conclude that genetic mutation in Mycobacterium tuberculosis can be identified directly from the clinical samples. However, we have carried this study in less sample size and to validate research on large number of sample is recommended.

Metallurgical Behaviour and Carbon Diffusion in Buttering Deposits Prepared With and Without Buffer Layers

Use of a buttering deposit on ferritic steel in dissimilar metal weld（DMW） joint is a common practice in nuclear plants to connect pressure vessel components（ferritic steel） to pipelines（austenitic stainless steel）.Carbon migration and metallurgical changes near fusion interface（ferritic steel–austenitic stainless steel） lead to a steeper gradient in material properties,and minimizing this gradient is the major challenge in the manufacturing of DMW joints.Inconel 82 is often deposited on ferritic steel material as buttering to reducing the gradient of physical and attaining material compatibility.Inconel 82/182 fillers are used to minimize the carbon migration,but the results are not truly adequate.In this paper,Ni–Fe alloy（chromium-free） has been used as the intermediate buffer layer in the weld buttering deposit to address the issue of carbon migration and subsequent metallurgical deterioration.The weld pads with and without buffer layers of Ni–Fe alloy have been investigated and compared in detail for metallurgical properties and carbon diffusivities.Ni–Fe buffer layer can significantly control the carbon migration which resists the metallurgical deterioration.It showed the better results in postweld heat treatment and thermally aged conditions.The buttering deposit with Ni–Fe buffer layer could be the better choice for DMW joints requirements.

Prevalence and current antibiogram trend of bacterial isolates of urinary tract infections in outpatients at Helping Hands Community Hospital,Kathmandu,Nepal

Objective:To ascertain the prevalence and antibiotic susceptibility pattern of bacteria from urinary tract infections.Methods:A retrospective analysis of bacterial pathogens and antibiogram was done in Helping Hands Community Hospital Laboratory from August to November,2014.Results:The prevalence of bacterial isolates was higher among females(44.70%)than males(31.34%)(P<0.001).The most common bacteria were Escherichia coli 35(59.32%),followed by coagulase-negative Staphylococcus 5(8.47%),Salmonella enterica 4(6.78%),Proteus mirabilis 2(3.39%),Proteus vulgaris 2(3.39%),Klebsiella pneumoniae 2(3.39%),Salmonella typhi 2(3.39%),Pseudomonas species 2(3.39%),Staphylococcus aureus 2(3.39%),Citrobacter species 2(3.39%),Acinetobacter baumannii 1(1.69%),Acinetobacter species 1(1.69%),Proteus vulgaris 1(1.69%).Conclusions:Most Gram-positive isolates were sensitive to nitrofurantoin,gentamycin and norfloxacin,and they are considered as appropriate microbials for empirical treatment of urinary tract infections.