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S. Ramanathan,M. R. Thansekhar,P. Rajesh Kanna,Prem Gunnasegaran 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.8
The relative positions of leading edges and trailing edges of rectangular vortex generators (VG) in the winglet form play a crucial role in modifying thermal and hydraulic boundary layers thereby affecting the heat transfer augmentation and pressure drop in a sudden expansion channel having expansion ratio (ER) 2:1. A numerical simulation was carried out for solving the momentum and energy equations of a three dimensional vortex- laminar flow (Reynolds number < 190) with a finite volume method based commercial code FLUENT 16.2. Reynolds number, angle of attack and VG configuration have been considered as influential parameters affecting the thermo-hydraulic performance of the sudden expansion channel due to the combined effect of primary recirculation and secondary vortex flow. The heat transfer enhancement along with corresponding pressure drop penalty was compared for the toe-out and toe-in configurations at various Reynolds (Re) numbers and angle of attacks (β). Eventually irrespective of configurations, rectangular winglet VGs are found to have better overall performance at β = 30° and β = 45° in both toe-out and toe-in configurations due to strong secondary vortex flow.
P. S. Samuel Ratna Kumar,R. Vaira Vignesh,P. M. Mashinini,S. Ramanathan 한국탄소학회 2023 Carbon Letters Vol.33 No.7
The present research focuses on the tribological behavior of the AA5083 alloy-based hybrid surface composite using aluminosilicate and multi-walled-carbon nanotube through friction stir processing for automotive applications. The friction stir processing parameters (tool rotation and traverse speed) are varied based on full factorial design to understand their influence on the tribological characteristics of the developed hybrid composite. The surface morphology and composition of the worn hybrid composite are examined using a field-emission scanning electron microscope and an energy-dispersive x-ray spectroscope. No synergistic interaction is observed between the wear rate and friction coefficient of the hybrid composite plate. Also, adhesive wear is the major wear mechanism in both base material and hybrid composite. The influence of friction stir process parameters on wear rate and the friction coefficient is analyzed using the hybrid polynomial and multi-quadratic radial basis function. The models are utilized to optimize the friction stir processing parameters for reducing the rate of wear and friction coefficient using multi-quadratic RBF algorithm optimization.
Durable keratin-based bilayered electrospun mats for wound closure
Singaravelu, Sivakumar,Ramanathan, Giriprasath,Muthukumar, Thangavelu,Raja, M. D.,Nagiah, Naveen,Thyagarajan, Sitalakshmi,Aravinthan, Adithan,P., Gunasekaran,Natarajan, T. S.,V. N. Geetha Selva, Ganga The Royal Society of Chemistry 2016 Journal of Materials Chemistry B Vol.4 No.22
<P>A bilayered nanofibrous scaffold with rapid wound healing properties is found to be suitable for tissue regeneration applications. The objective of this study is to reveal the fabrication of a poly(3-hydroxybutyric acid) (P)-gelatin (G) nanofibrous mat through electrospinning, with a horn keratin-chitosan-based biosheet (KC) as a bilayered nanofibrous scaffold. The mupirocin (D)-loaded horn KC biosheet (KCD) acts as the primary layer over which PG nanofibers were electrospun to act as the secondary layer. It is shown that this engineered bilayered nanofibrous scaffold material (KC-PG) should fulfill the functions of the extracellular matrix (ECM) by elucidating its function<I>in vitro</I>and<I>in vivo</I>. The bilayered nanofibrous scaffold was designed to exhibit improved physiochemical, biological and mechanical properties, with better swelling and porosity for enhanced oxygen permeability, and it also exhibits an acceptable antibacterial property to prevent infection at the wound site. The bilayered nanofibrous scaffold assists in better biocompatibility towards fibroblast and keratinocyte cell lines. The morphology of the nanofibrous scaffold aids increased cell adhesion and proliferation with cell material interactions. This was elucidated with the help of<I>in vitro</I>fluorescence staining against both cell lines. The bilayered KCD-PG nanofibrous scaffold material gives accelerated wound healing efficiency during<I>in vivo</I>wound healing. The results showed the regulation of growth factors with enhanced collagen synthesis, thereby helping in faster wound healing.</P>
Chung, C. E.,Ramanathan, V.,Carmichael, G.,Kulkarni, S.,Tang, Y.,Adhikary, B.,Leung, L. R.,Qian, Y. Copernicus GmbH 2010 Atmospheric Chemistry and Physics Vol.10 No.13
<P>Abstract. An estimate of monthly 3-D aerosol solar heating rates and surface solar fluxes in Asia from 2001 to 2004 is described here. This product stems from an Asian aerosol assimilation project, in which a) the PNNL regional model bounded by the NCEP reanalyses was used to provide meteorology, b) MODIS and AERONET data were integrated for aerosol observations, c) the Iowa aerosol/chemistry model STEM-2K1 used the PNNL meteorology and assimilated aerosol observations, and d) 3-D (X-Y-Z) aerosol simulations from the STEM-2K1 were used in the Scripps Monte-Carlo Aerosol Cloud Radiation (MACR) model to produce total and anthropogenic aerosol direct solar forcing for average cloudy skies. The MACR model and STEM-2K1 both used the PNNL model resolution of 0.45°×0.4° in the horizontal and of 23 layers in the troposphere. The 2001-2004 averaged anthropogenic all-sky aerosol forcing is −1.3 Wm−2 (TOA), +7.3 Wm−2 (atmosphere) and −8.6 Wm−2 (surface) averaged in Asia (60-138° E and Equator-45° N). In the absence of AERONET SSA assimilation, absorbing aerosol concentration (especially BC aerosol) is much smaller, giving −2.3 Wm−2 (TOA), +4.5 Wm−2 (atmosphere) and −6.8 Wm−2 (surface), averaged in Asia. In the vertical, monthly forcing is mainly concentrated below 600 hPa with maximum around 800 hPa. Seasonally, low-level forcing is far larger in dry season than in wet season in South Asia, whereas the wet season forcing exceeds the dry season forcing in East Asia. The anthropogenic forcing in the present study is similar to that in Chung et al. (2005) in overall magnitude but the former offers fine-scale features and simulated vertical profiles. The interannual variability of the computed anthropogenic forcing is significant and extremely large over major emission outflow areas. Given the interannual variability, the present study's estimate is within the implicated range of the 1999 INDOEX result. </P>
Swamikannu, Bhuminathan,Kumar, Kishore S.,Jayesh, Raghavendra S.,Rajendran, Senthilnathan,Muthupalani, Rajendran Shanmugam,Ramanathan, Arvind Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.5
Background: Dilantin sodium (phenytoin) is an antiepileptic drug, which is routinely used to control generalized tonic clonic seizure and partial seizure episodes. A few case reports of oral squamous cell carcinomas arising from regions of phenytoin induced gingival overgrowth (GO), and overexpression of mitogenic factors and p53 have presented this condition as a pathology with potential to transform into malignancy. We recently investigated the genetic status of p53 and H-ras, which are known to be frequently mutated in Indian oral carcinomas in GO tissues and found them to only contain wild type sequences, which suggested a non-neoplastic nature of phenytoin induced GO. However, besides p53 and H-ras, other oncogenes and tumor suppressors such as PIK3CA, p14ARF, p16INK4a and $p21^{Waf1/Cip1}$, are frequently altered in oral squamous cell carcinoma, and hence are required to be analyzed in phenytoin induced GO tissues to be affirmative of its non-neoplastic nature. Methods: 100ng of chromosomal DNA isolated from twenty gingival overgrowth tissues were amplified with primers for exons 9 and 20 of PIK3CA, exons $1{\alpha}$, $1{\beta}$ and 2 of p16INK4a and p14ARF, and exon 2 of $p21^{Waf1/Cip1}$, in independent reactions. PCR amplicons were subsequently gel purified and eluted products were sequenced. Results: Sequencing analysis of the twenty samples of phenytoin induced gingival growth showed no mutations in the analyzed exons of PIK3CA, p14ARF, p16INK4a and $p21^{Waf1/Cip1}$. Conclusion: The present data indicate that the mutational alterations of genes, PIK3CA, p14ARF, p16INK4a and $p21^{Waf1/Cip1}$ that are frequently mutated in oral squamous cell carcinomas are rare in phenytoin induced gingival growth. Thus the findings provide further evidence that phenytoin induced gingival overgrowth as a non-neoplastic lesion, which may be considered as clinically significant given the fact that the epileptic patients are routinely administered with phenytoin for the rest of their lives to control seizure episodes.