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Morphological and Mechanical Behaviour of Cu–Sn Alloys—A review
M. Karthik,J. Abhinav,Karthik V. Shankar 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7
The current paper reviews the research conducted on wrought Cu–Sn, Cu–Sn–Ti and Cu–Sn–Zn alloys intending to revealthe details on morphological and mechanical behaviour during various manufacturing operations. The motivational force ofemploying copper-based alloys in automotive and marine industries is its mechanical properties and corrosion resistance. One of the important factors that afect mechanical properties is micrograph. The grain size, grain distribution, heat treatment, morphological behaviour and the intermediate phase formation highly infuence the properties of the copper-basedalloys. Moreover, the change in microstructure through diferent manufacturing process (wrought process), heat treatmentand addition of alloying element also improve the mechanical and thermal properties. This paper aims to review the majorconclusions on improving the microstructure and mechanical behaviour of wrought Cu–Sn, Cu–Sn–Zn and Cu–Sn–Ti alloys. Analysis and observations of each investigation were prepared by incorporating the morphological results obtained throughOptical Microscope, Transmission Electron Microscope, Scanning Electron Microscope, X-ray Difraction Technique andElectron Dispersive Spectroscopy. This review paper also attempts to give the areas of future researches and developmentsthat can be made for these wrought alloys.
Karthik Paneer Selvam,Taichi Nagahata,Kosuke Kato,Mayuko Koreishi,Toshiyuki Nakamura,Yoshimasa Nakamura,Takeshi Nishikawa,Ayano Satoh,Yasuhiko Hayashi 한국생체재료학회 2020 생체재료학회지 Vol.24 No.4
Background: Conductive sheets of cellulose and carbon nanomaterials and its human skin applications are an interesting research aspect as they have potential for applications for skin compatibility. Hence it is needed to explore the effects and shed light on these applications. Method: To fabricate wearable, portable, flexible, lightweight, inexpensive, and biocompatible composite materials, carbon nanohorns (CNHs) and hydroxyethylcellulose (HEC) were used as precursors to prepare CNH-HEC (Cnh-cel) composite sheets. Cnh-cel sheets were prepared with different loading concentrations of CNHs (10, 20 50,100 mg) in 200 mg cellulose. To fabricate the bio-compatible sheets, a pristine composite of CNHs and HEC was prepared without any pretreatment of the materials. Results: The obtained sheets possess a conductivity of 1.83 × 10− 10 S/m and bio-compatible with human skin. Analysis for skin-compatibility was performed for Cnh-cel sheets by h-CLAT in vitro skin sensitization tests to evaluate the activation of THP-1 cells. It was found that THP-1 cells were not activated by Cnh-cel; hence Cnh-cel is a safe biomaterial for human skin. It was also found that the composite allowed only a maximum loading of 100 mg to retain the consistent geometry of free-standing sheets of < 100 μm thickness. Since CNHs have a unique arrangement of aggregates (dahlia structure), the composite is homogeneous, as verified by transmission electron microscopy (TEM) and, scanning electron microscopy (SEM), and other functional properties investigated by Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), conductivity measurement, tensile strength measurement, and skin sensitization. Conclusion: It can be concluded that cellulose and CNHs sheets are conductive and compatible to human skin applications.
Karthik A. R.,Gupta Nishkarsh,Garg Rakesh,Bharati Sachidanand Jee,Ray M. D.,Hadda Vijay,Pahuja Sourabh,Mishra Seema,Bhatnagar Sushma,Kumar Vinod 대한마취통증의학회 2024 Korean Journal of Anesthesiology Vol.77 No.3
Background: Existing literature lacks high-quality evidence regarding the ideal intraoperative positive end-expiratory pressure (PEEP) to minimize postoperative pulmonary complications (PPCs). We hypothesized that applying individualized PEEP derived from electrical impedance tomography would reduce the severity of postoperative lung aeration loss, deterioration in oxygenation, and PPC incidence.Methods: A pilot feasibility study was conducted on 36 patients who underwent open abdominal oncologic surgery. The patients were randomized to receive individualized PEEP or conventional PEEP at 4 cmH2O. The primary outcome was the impact of individualized PEEP on changes in the modified lung ultrasound score (MLUS) derived from preoperative and postoperative lung ultrasonography. A higher MLUS indicated greater lung aeration loss. The secondary outcomes were the PaO2/FiO2 ratio and PPC incidence.Results: A significant increase in the postoperative MLUS (12.0 ± 3.6 vs 7.9 ± 2.1, P < 0.001) and a significant difference between the postoperative and preoperative MLUS values (7.0 ± 3.3 vs 3.0 ± 1.6, P < 0.001) were found in the conventional PEEP group, indicating increased lung aeration loss. In the conventional PEEP group, the intraoperative PaO2/FiO2 ratios were significantly lower but not the postoperative ratios. The PPC incidence was not significantly different between the groups. Post-hoc analysis showed the increase in lung aeration loss and deterioration of intraoperative oxygenation correlated with the deviation from the individualized PEEP.Conclusions: Individualized PEEP appears to protect against lung aeration loss and intraoperative oxygenation deterioration. The advantage was greater in patients whose individualized PEEP deviated more from the conventional PEEP.
Karthik M.,Narmadhai N. 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.3
Transformers are most vibrant equipment of power system network and petroleum base mineral oil is used as dielectric insulating medium and cooling medium. At present more research works are focused towards natural esters based fl uids as prospectivedisplace to traditional mineral oil, due to similar properties of transformer oil, high availability of resources, high biodegradability and environmental friendly nature. This work emphasizes on enhancement of properties of natural ester using antioxidants. Natural esters such as mustard oil, rice bran oil, punna oil and castor oil are chosen for investigation along with antioxidants such as gallic acid, citric acid, propyl gallate and tertiary butylated hydroxy quinone. Natural esters are mixed with 1 g, 2 g, 3 g and 5 g of antioxidants for the investigations. The critical properties like breakdown voltage, fl ash point, fi re point, viscosity, interfacial tension, water content and acidity of natural esters are analyzed based on IEC/ASTM standards before and after addition of antioxidants. From this study, it is noted that antioxidants improve the characteristics of natural esters after addition of it and properties are superior to the traditional mineral oil.By the suitable proportion of fl uids the 80–90% of characteristics betterment are achieved with the infl uence of fatty acid based additives.
An Aortic Root Abscess Presenting as a Suprasternal Pulsatile Mass
Karthik Raman,Ejaz Ahmed Sheriff,Jacob Jamesraj,Ram Kumar 대한흉부외과학회 2019 Journal of Chest Surgery (J Chest Surg) Vol.52 No.3
Prosthetic valve endocarditis with aortic root abscess is a serious condition requiring urgent surgical intervention. We present a case caused by an infected Bentall mechanical valve conduit after cardiac surgery in a patient who was referred for a suprasternal pulsatile mass. The patient also had 1 episode of sentinel haemorrhage.
Hybrid sol-gel/thiourea binary coating for the mitigation of copper corrosion in neutral medium
Karthik, Namachivayam,Lee, Yong Rok,Sethuraman, Mathur Gopalakrishnan Elsevier 2017 Progress in organic coatings Vol.102 No.2
<P><B>Abstract</B></P> <P>A versatile approach was adopted for mitigation of the corrosion of copper in neutral medium. Initially, a well-known corrosion inhibitor (viz., a thiourea (TU) film) was electrodeposited over the copper surface. Secondly, an environmentally-friendly hybrid sol-gel (Hy) coating consisting of (3-glycidoxypropyl)methyldiethoxysilane (GPTMS) and tetraethyl orthosilicate (TEOS) was immobilized on the thiourea-modified copper surface via an epoxy amine cross-linking reaction to form a binary coating. Thereafter, the individual and combined characteristics of the binary coating were studied via spectroscopic and microscopic analyses. The effectiveness of these binary coatings on mitigation of copper corrosion was scrutinized by electrochemical techniques, viz., electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP) studies. The results revealed that the binary coating mitigated copper corrosion to a great extent in a complementary and robust manner.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This work explores the formation of thiourea and hybrid sol-gel coatings on copper. </LI> <LI> Thiourea alone protects copper from corrosion only in a limited range. </LI> <LI> Binary coating of hybrid sol-gel and thiourea provide robust copper corrosion mitigation. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>