Tribological and Nano‑Scratch Properties of Aluminum (A356) Based Hybrid Composites Reinforced with MWCNTs/Alumina Fiber

J. S. S. Babu,A. Srinivasan,Chung Gil Kang 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.9

In this article, the tribological properties of aluminum/MWCNTs/Al2O3sf hybrid composites with varying volume fractionof 10 vol%, 15 vol% and 20 vol% was investigated under dry sliding conditions. The experiments were performed accordingto design of experiments approach using Taguchi method to predict the wear properties of composites. The results indicatedthat the composites of 15 vol% had lower wear loss, whereas the coefficient of friction (COF) decreased significantly at 20vol%. Taguchi based ANOVA analysis showed that the sliding distance was found to be the prominent factor controllingthe wear loss; applied load influenced COF most significantly. It could also be noticed that the COF and wear loss increaseswith an increase in sliding load and sliding distance. The decrease in wear loss and the COF can be attributed to the selflubricationeffect of MWCNTs, and the combined effect of reinforcements in the composites. In addition, nanoscratch testwas performed to determine the COF and the effect of the reinforcements on local regions of the composites. The resultsrevealed that higher friction force was obtained near the regions of MWCNTs and Al2O3sfwhile nanoscratching. The COFof composites of 20 vol% was found to slightly higher compared to that of 10 vol% and 15 vol%. This is attributed to thepresence of MWCNTs cluster within the Al2O3sfnetwork results prevent the micro-plastic deformation of Al matrix, and theformation of tribofilms with nanoscaled thickness in the scratch region. These friction and wear results indicate that the presenceof a limited amount and size of MWCNTs clusters are beneficial to the tribological properties of the hybrid composites.

Rearrangement mechanisms for azoxypyridines and azoxypyridine <i>N</i>-oxides in the 100% H₂SO₄ region - The Wallach rearrangement story comes full circle

Buncel, Erwin,Keum, Sam-Rok,Rajagopal, Srinivasan,Cox, Robin A. Canadian Science Publishing 2009 Canadian journal of chemistry Vol.87 No.8

<P> Kinetic studies of the Wallach rearrangements of four azoxypyridines, four azoxypyridine N-oxides, and one azoxypyridine N-methiodide have been carried out in the 100% H2SO4 acidity region. For all of the β-isomers in the study the reactions proceeded at a spectrally measurable rate, and the log observed rate constants were found to be linear functions of the log H3SO4<SUP>+ </SUP> concentration, as previously found for azoxybenzene itself, suggesting that the reaction mechanism for these substrates is the same as that previously deduced for axozybenzene, i.e., a general-acid-catalysis A-SE2 process. For the α-azoxypyridines no reaction could be observed at all. The two α-azoxypyridine N-oxides in the study did react, albeit very slowly, but for these two compounds the log observed rate constants were not linear functions of the log H3SO4<SUP>+ </SUP>concentration, but were instead found to be linear in the H0 acidity function, which is known for the 100% H2SO4 acidity region. It follows that the reaction mechanism for these α-isomers is a different one, presumably an A1 process. This mechanism was proposed back in 1963 for azoxybenzene, but has never actually been observed for any substrate before the work reported in this study. Thus, the Wallach rearrangement story can be said to have come full circle. </P>

Nano and macromechanical properties of aluminium (A356) based hybrid composites reinforced with multiwall carbon nanotubes/alumina fiber

Babu, JSS,Srinivasan, A,Kang, CG SAGE Publications 2017 Journal of composite materials Vol.51 No.11

Tessaracoccus defluvii sp. nov., isolated from an aeration tank of a sewage treatment plant

Srinivasan, S.,Sundararaman, A.,Lee, S. S. Kluwer Academic Publishers [etc.] 2017 Antonie van Leeuwenhoek Vol.110 No.1

<P>A Gram-positive, non-motile, aerobic, coccus-shaped bacterium, designated strain LNB-140(T), was isolated from a sewage treatment plant in the Republic of Korea and was characterised using a polyphasic taxonomic approach. Comparative 16S rRNA gene sequence analysis showed that strain LNB-140(T) belongs to genus Tessaracoccus in the family Propionibacteriaceae of the phylum Actinobacteria. The 16S rRNA gene sequence similarities between strain LNB-140(T) and type strains of the genus, Tessaracoccus flavescens SST-39(T) and Tessaracoccus rhinocerotis YIM101269(T) are 97.8 and 97.4 %, respectively. The chemotaxonomic properties of strain LNB-140(T) are consistent with those of members of the genus Tessaracoccus: a quinone system with MK-9(H4) as the predominant menaquinone; anteiso-C-15:0 and iso C-15:0 as the predominant cellular fatty acids; and ll-2,6-diaminopimelic acid as the diagnostic peptidoglycan diamino acid. The major polar lipids were identified as diphosphatidylglycerol and phosphatidylethanolamine. The G+C content of the genomic DNA was determined to be 67.1 mol%. Differential phenotypic properties along with low DNA-DNA relatedness (< 30 +/- 3.2 %) with closely related type strains show that strain LNB-140(T) is distinct from previously described members of the genus Tessaracoccus and represents a novel species in this genus, for which the name Tessaracoccus defluvii sp. nov. is proposed. The type strain is LNB-140(T) (=KEMB 5401-076(T) = JCM 17540(T)).</P>

The effect of sliding wear parameters on carburized AISI1040 steel

A. Arulbrittoraj,P. Padmanabhan,M. Duraiselvam,R. Srinivasan,G. Ebenezer 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.4

This study aims to investigate the effect of wear parameters and wear behavior on gas carburized AISI1040 steel. Scanning electron microscope images reveal that carburizing has been observed for a depth of 393 ± 23 µm from the surface. The Vickers microhardness test has been conducted on the cross section of the sample, which has a maximum hardness of 423 ± 18 HV near the surface and 220 ± 15 HV near the interface. The pin-on-disk apparatus has been employed to investigate sliding wear performance by varying the applied load and sliding distance. The applied load, sliding distance, and temperature of the steel pin are selected as the wear parameters, which affect the wear resistance and friction behavior. After the investigation, the sliding distance is determined to be a significant parameter, followed by the applied load and temperature of the steel pin.

Investigation and optimization on micro and nano Al2O3 reinforced aluminium composites using GRA coupled PCA technique

A. Srinivasan,R. Prabu,S. Ramesh,R. Viswanathan 한양대학교 청정에너지연구소 2022 Journal of Ceramic Processing Research Vol.23 No.6

Aluminum alloy are widely adopted material for engineering applications in automobile, aircraft and marine industries. Itshigh strength to weight ratio attracts modern industry to extend its applications in various domains. For producing variouscomponents, turning is the most reputed machining operation. The method of manufacturing directly impacts the productaccuracy. The present research deals with fabrication and optimization study in dry turning of LM25 Aluminium MetalMatrix Composites (AMMCs). For AMMC fabrication, 10 wt.% of micro and nano Al2O3 ceramic particle is added asreinforcement. Hybrid Grey Relational Analysis (GRA) coupled Principal Component Analysis (PCA) technique is suggestedfor finding optimization results. Experiment was conducted with cutting speed (V), feed rate (f), and depth of cut(d) as inputparameters. Based on optimization, feed rate dominates the entire turning process compared to cutting speed and depth of cutand 12.95% improvement of GRA was achieved at the end of confirmation experiment.

Nanocrystalline cerium oxide coated fiber optic gas sensor

B. Renganathan,D. Sastikumar,A. Chandra Bose,R. Srinivasan,A.R. Ganesan 한국물리학회 2014 Current Applied Physics Vol.14 No.3

A clad-modified fiber optic sensor with nanocrystalline CeO2 is proposed for gas detection. As-prepared and annealed CeO2 (500 C) samples have been used as gas sensing media. The spectral characteristics of the fiber optic gas sensor are studied for various concentrations of ammonia, ethanol and methanol gases (0e500 ppm). The sensor exhibits linear variation in the spectral peak intensity with the gas concentration. The characteristics of the sensor are also studied for gas selectivity. The time response characteristics of the sensor are reported.

Numerical Modelling on Stress and Dislocation Generation in Multi-Crystalline Silicon during Directional Solidification for PV Applications

M. Srinivasan,P. Karuppasamy,P. Ramasamy,A. K. Barua 대한금속·재료학회 2016 ELECTRONIC MATERIALS LETTERS Vol.12 No.4

Numerical modelling has emerged as a powerful tool for the development andoptimization of directional solidification process for mass production of multicrystallinesilicon. A transient global heat transfer model is performed to investigate theeffect of bottom grooved furnace upon the directional solidification (DS) process ofmulti-crystalline silicon (mc-Si). The temperature distribution, von Mises stress,residual stress and dislocation density rate in multi-crystalline silicon ingots grown bymodified directional solidification method have been investigated for five growth stagesusing finite volume method at the critical Prandtl number, Pr = 0.01. This paperdiscusses bottom groove furnace instead of seed crystal DS method. It achieves anadvanced understanding of the thermal and mechanical behaviour in grown multicrystallineingot by bottom grooved directional solidification method. The von Misesstress and dislocation density were reduced while using the bottom grooved furnace. This work was carried out in the different grooves of radius 30 mm, 60 mm and 90 mmof the heat exchanger block of the DS furnace. In this paper, the results are presented for60 mm radius groove only because it has got better results compared to the othergrooves. Also, the computational results of bottom grooved DS method show betterperformance compared the conventional DS method for stress and dislocation densityin grown ingot.

Noviherbaspirillum humi sp. nov., isolated from soil

Sundararaman, A.,Srinivasan, S.,Lee, S. S. Springer Science + Business Media 2016 Antonie van Leeuwenhoek Vol.109 No.5

<P>Two novel Gram-stain negative, motile, non-spore forming, facultative aerobic and short rod shaped bacterial strains, designated U15(T) and U32, were isolated from soil obtained from Ukraine. The sequence similarity of the 16S rRNA gene between strains U15(T) and U32 was found to be 99.5 %. Phylogenetic analysis based on 16S rRNA gene sequences confirmed that new bacteria belong to the genus Noviherbaspirillum. The closest member of the genus was found to be Noviherbaspirillum malthae (97.0 %) followed by Noviherbaspirillum suwonensis (96.3 %). The novel isolates was observed to grow optimally at 30 A degrees C and pH 7.0. The major fatty acids present in the two strains were identified as summed feature 3 (C-16:1 omega 7c/C-16:1 omega 6c), C-16:0, and summed feature 8 (C-18:1 omega 7c/C-18:1 omega 6c). Ubiquinone 8 was identified as the respiratory quinone component for both the strains. The polar lipid (L) profile contained phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, aminophospholipid, unidentified aminolipid and unidentified Ls, and putrescine and 2-hydroxyputrescine as major polyamines. The G+C content of the DNA for the strain U15(T) was found to be 61.2 mol%. The DNA-DNA relatedness between U15(T) and U32 and closely related species was less than 40 %. Based on the polyphasic taxonomic analysis, a new species, Noviherbaspirillum humi sp. nov., is proposed. The type strain is strain U15(T) = JCM 19873(T) = KEMB 7305-102(T).</P>

Right Ventricular Strain Is Associated With Increased Length of Stay After Tetralogy of Fallot Repair

Ranjini Srinivasan,Jennifer A. Faerber,Grace DeCost,Xuemei Zhang,Michael DiLorenzo,Elizabeth Goldmuntz,Mark Fogel,Laura Mercer-Rosa 한국심초음파학회 2022 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.30 No.1

BACKGROUND: Little is known regarding right ventricular (RV) remodeling immediately after Tetralogy of Fallot (TOF) repair. We sought to describe myocardial deformation by cardiac magnetic resonance imaging (CMR) after TOF repair and investigate associations between these parameters and early post-operative outcomes. METHODS: Fifteen infants underwent CMR without sedation as part of a prospective pilot study after undergoing complete TOF repair, prior to hospital discharge. RV deformation (strain) was measured using tissue tracking, in addition to RV ejection fraction (EF), volumes, and pulmonary regurgitant fraction. Pearson correlation coefficients were used to determine associations between both strain and CMR measures/clinical outcomes. RESULTS: Most patients were male (11/15, 73%), with median age at TOF repair 53 days (interquartile range, 13,131). Most patients had pulmonary stenosis (vs. atresia) (11/15, 73%) and 7 (47%) received a transannular patch as part of their repair. RV function was overall preserved with mean RV EF of 62% (standard deviation [SD], 9.8). Peak radial and longitudinal strain were overall diminished (mean ± SD, 33.80 ± 18.30% and −15.50 ± 6.40%, respectively). Longer hospital length of stay after TOF repair was associated with worse RV peak radial ventricular strain (correlation coefficient (r), −0.54; p = 0.04). Greater pulmonary regurgitant fraction was associated with shorter time to peak radial RV strain (r = −0.55, p = 0.03). CONCLUSIONS: In this small study, our findings suggest presence of early decrease in RV strain after TOF repair and its association with hospital stay when changes in EF and RV size are not yet apparent.