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MADHULEKHA GOGOI,PRITAM DEB 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.4
The magnetic control on scattering of light by ultra¯ne iron oxide (?-Fe2O3) nanoparticles suspended in a carrier liquid was investigated. The light scattering behavior was studied using laser light under the in°uence of a permanent magnet over a rotating frame of reference. When the magnet is rotated continuously from 0? to 360? with respect to the direction of the incident laser beam, the scattered light pattern from the sample has the same angular displacement but in counter direction to the magnetic ¯eld rotation. When external ¯eld is not applied to the ferro°uid, no other preferred directional scattering of light is observed. The applied magnetic ¯eld induces directional self assembly of magnetic nanoparticles through dipole?dipole interactions. This ¯nally leads to the formation of \nanoparticle grating" and the optical geometry of diffraction grating clearly describes the anomalous scattering behavior of the ferro°uid. Most interestingly, for each complete orientation of the ¯eld from 0? to 360?, the transmitted light intensity switches between maxima and minima for longitudinal and transverse applied magnetic ¯elds.
Kashmiri Deka,Anupam Guleria,Dinesh Kumar,Jayeeta Biswas,Saurabh Lodha,Som Datta Kaushik,Suman Dasgupta,PRITAM DEB 한국물리학회 2020 Current Applied Physics Vol.20 No.1
Single mode (either T1 or T2) contrast agents employed during magnetic resonance imaging owe their advantage over their dual counterparts to the fact that they do not involve any quenching caused by interference between the two modes. The chemistry involving oxides of manganese is highly significant due to their applicability as MRI contrast agents. Manganese oxides are usually known to display a dominant T1 relaxation enhancement. But, in this work, an engineered structure of manganese oxide (Mn2O3) nanoparticles encapsulated within mesoporous carbon frameworks was developed which exhibited dominant T2 contrast enhancement, through regulation of contact between the magnetic ion and water. Microstructural characterization revealed that the mesoporous carbon frameworks were spherical in shape and the nanoparticles within them had an average size of 40–50 nm. Relaxivity measurement, MRI experiments and cell viability assay convincingly established the system as a new class of biocompatible T2 based magnetic resonance imaging agent.