Numerical Investigation of Shock Wave-Boundary Layer Interactions Inside Scramjet Inlet

Kavan M Prabtani,Rajesh Ranjan 한국전산유체공학회 2022 한국전산유체공학회 학술대회논문집 Vol.2022 No.10

Mechanical and Thermal Characterization of Camphor Soot Embedded Coir Fiber Reinforced Nylon Composites

T. Raghavendra,Panneerselvam Kavan 한국섬유공학회 2020 Fibers and polymers Vol.21 No.11

In this study, camphor soot was infused into coir fibers using osmosis technique. Further, modified coir fibers werereinforced in nylon 6 using the melt intercalation method by varying fiber content (0, 3, 6, 9 wt. %) to obtain camphor sootembedded coir fiber reinforced nylon composites (CSCFNCs). The presence of camphor soot infused coir fibers in nylon 6matrix was confirmed through XRD peaks by forming a single peak for CSCFNCs compared to neat nylon 6. CSCFNCswere characterized for tensile strength, flexural strength, impact strength and density as per ASTM standards. Thermalbehaviour of CSCFNCs were also investigated by TGA, DSC, MFI and DMA. Tensile strength, flexural strength and densityof the CSCFNCs were enhanced compared to neat nylon 6. On the other hand, impact strength is reduced. MFI and tan δvalues for CSCFNCs shows decreased trend due to constrained polymer movement. TGA analysis for CSCFNCs showsincreased thermal stability, marginally. DSC analysis revealed two peaks at 228 °C and 468 °C corresponds to the meltingpoint and degradation temperature of CSCFNCs respectively. DMA result shows the storage modulus of 700 MPa for neatnylon 6 and it is enhanced in the case of CSCFNCs. Maximum storage modulus was recorded for 6 wt. % CSCFNCs was806 MPa. Creep study shows that 6 wt. % CSCFNCs has shown minimum impression depth 0.125 mm compared to neatnylon 6 0.212 mm. SEM reveals that the fibers are uniformly distributed in the matrix and experienced brittle fracture.

A Novel Study on Thermal Stability of Camphor Soot Reinforced Coir Fibers

T. Raghavendra,Panneerselvam Kavan 한국섬유공학회 2018 Fibers and polymers Vol.19 No.7

Thermoplastics, reinforced with lignocellulosic fibers are usually processed at lower temperatures ranging from 100 oC to 160 oC. Further increase in temperature leads to the degradation of the fibers mechanical properties. Camphor soot reinforced coir fibers (CSRCF) based on the osmosis technique were prepared, in this study. Parameters using Design of Experiments (DOE) varied and the process is investigated for varied camphor soot concentrations (0.5, 1.0 and 1.5 wt. %), time (4, 8 and 12 hrs.) and temperature (30, 40 and 50 oC) with three levels for each parameter (L9 Orthogonal array). Relative camphor soot content in the coir fiber (RCSCF) and tensile strength are vital objective functions. Tensile tests were conducted on tensometer according to DOE, and based on analysis of variance (ANOVA). The optimal results from ANOVA were established by charting the main effect plots. The optimal combination of parameters for CSRCF were examined using X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transform infrared radiation (FTIR). Further, scanning electron microscope (SEM) equipped with an energy dispersion spectroscope (EDS) examined and compared neat fibers. The results showed a considerable increase in tensile strength by about 37 % for CSRCF compared to neat fibers. XRD revealed that crystallinity index was slightly reduced for modified fibers. The TGA result reveals that thermal stability of the modified fibers improved by 15 % compared to neat fibers. FTIR analysis revealed that modified fibers experienced peak diminishing in OH, CH stretching and carbonyl groups. The Morphology study of neat and CSRCF were examined using SEM with EDS analysis which revealed 94 % carbonaceous compounds in a cross examination of modified fibers compared to the cross section of a neat coir fiber (64 %).

SPECTROELECTROCHEMICAL RECOGNITION OF CHEMICAL DOPANTS IN THE INNER SPACE OF CARBON NANOSTRUCTURES

MARTIN KALBÁČ,LADISLAV KAVAN,MARKÉTA ZUKALOVÁ,LOTHAR DUNSCH 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2006 NANO Vol.1 No.3

By in situ Raman spectroelectrochemistry the state of chemical dopants in the inner space of potassium vapor treated single-walled carbon nanotubes (SWCNT), double-walled carbon nanotubes (DWCNT) and C60 fullerene peapods was followed. We show that the spectroelectrochemistry is a method of choice to locate the dopant within carbon nanostructures. The presence of potassium inside the carbon nanostructures was found to be associated with a characteristic response of the tangential (TG) mode of SWCNT to electrochemical doping after treatment of the sample with the water. Our study confirmed the presence of residual potassium in peapods even after treatment with water. On the other hand, potassium was not found in the interior of the water-treated DWCNT and SWCNT.

Versatile Role of 1 8 F-FDG PET/CT in a Patient with Pan-cerebellar Paraneoplastic Manifestation Due to Underlying Hodgkin’s Lymphoma

Piyush Aggarwal,Anwin Joseph Kavanal,Harmandeep Singh,Rajender Kumar,Rajeev Ranjan,Jitupam Baishya,Anish Bhattacharya 대한핵의학회 2021 핵의학 분자영상 Vol.55 No.6

Hodgkin’s lymphoma most commonly presents as painless lymphadenopathy and systemic B symptoms like fever, nightsweats, and weight loss. But rarely, it can present with unusual paraneoplastic manifestations. In the present case, we reporta 30-year-old woman who presented with sub-acute onset pan-cerebellar symptoms. The serum neuronal antibody panel wasnegative. She underwent F-18 FDG PET/CT to evaluate the neoplastic etiology as the underlying cause, which demonstratedboth the primary etiology and the paraneoplastic changes in the brain.

[68 Ga]Ga-PSMA-11 Small Bowel Uptake in Crohn’s Disease: Revisiting the “Non-specificity” of PSMA Ligands

Kunal Ramesh Chandekar,Sindhu Tanigassalam,Anwin Joseph Kavanal,Singh Harmandeep,Anish Bhattacharya,Ravimohan Suryanarayan Mavuduru 대한핵의학회 2022 핵의학 분자영상 Vol.56 No.2

The rapidly evolving clinical utility of prostate-specific membrane antigen (PSMA) PET/CT as an imaging modality for prostate cancer (PCa) has brought to the forefront a multitude of non-prostatic diseases also exhibiting PSMA radioligand uptake. We report a case of a 71-year-old male with PCa who underwent PSMA PET/CT for recurrence evaluation. The scan demonstrated [68 Ga]Ga-PSMA-11 uptake in the distal ileum. Retrospective enquiry revealed that the patient was a known case of Crohn’s disease. This case highlights an uncommon finding of PSMA radioligand uptake in the distal small bowel (non-prostatic benign pathological uptake) in a patient with known Crohn’s disease, which may be misinterpreted in the evaluation of PCa.

Modeling Ruthenium-Dye-Sensitized TiO₂ Surfaces Exposing the (001) or (101) Faces: A First-Principles Investigation

De Angelis, Filippo,Vitillaro, Giuseppe,Kavan, Ladislav,Nazeeruddin, Mohammad. K.,Grä,tzel, Michael American Chemical Society 2012 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.116 No.34

<P>We present a first-principles computational investigation on the adsorption mode and electronic structure of the highly efficient heteroleptic ruthenium dye C101, [NaRu(4,4′-bis(5-hexylthiophene-2-yl)-2,2′-bipyridine)(4-carboxylic acid-4′-carboxylate-2,2′-bipyridine)(NCS)<SUB>2</SUB>], on anatase TiO<SUB>2</SUB> models exposing the (001) and (101) surfaces. The electronic structure of the TiO<SUB>2</SUB> models shows a conduction band energy upshift for the (001)-surface ranging between ∼50 and ∼110 meV compared with the (101) surface, in agreement with previous interfacial impedance and recent spectro-electrochemical data. TDDFT excited-state calculations provided the same optical band gap, within 0.01 eV, for the (001)- and (101) models. Two dominant adsorption modes for C101 dye adsorption on the (001) and (101) surfaces were found, which differ by the binding of the dye carboxylic groups to the TiO<SUB>2</SUB> surfaces (bridged bidentate vs monodentate), leading to sizably different tilting of the anchoring bipyridine plane with respect to the TiO<SUB>2</SUB> surface. The different adsorption mode leads to a smaller dye coverage on the (001) surface, as experimentally found, due to partial contact of the thiophene and alkyl bipyridine substituents with the TiO<SUB>2</SUB> surface. For the energetically favored adsorption modes, we calculate a larger average spatial separation, by 1.3 Å, between the dye-based HOMO and the semiconductor surface in (001) and (101) TiO<SUB>2</SUB> models. In terms of simple nonadiabatic electron-transfer considerations, our model predicts a retardation of the charge recombination kinetics, in agreement with the experimental observations.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2012/jpccck.2012.116.issue-34/jp306186y/production/images/medium/jp-2012-06186y_0008.gif'></P>