Characterization of Rock Materials based on Signal Emission levels Under Uni-Axial Compression

K.U.M. Rao,Subir Kumar Ghosh,Sudipta Bhattacharjee,D. Deb,Samir K.Pal 한국암반공학회 2010 한국암반공학회 학술대회 및 세미나 자료집 Vol.2010 No.10

Characterization of engineering materials is an essential aspect of manufacturing, since the properties of both the job and the tool influence each other. Experimental work is conducted to detect acoustic, vibration and electromagnetic emissions produced during uniaxial compressive loading of rock specimens. Preliminary results of testing limestone, quartz and sandstone rock specimens are presented. Some results of testing granite and coal samples are also presented. Results indicate that different types of AE, vibration and EM signals are produced during testing of a rock type to failure. In rock drilling one of the main consumables is the cutting tool. The performance of the cutting tool and its life is also controlled by the properties of the job (rock). The present work aims at characterization of rock material based on the physical and mechanical properties, as well as the levels of acoustic emissions and electromagnetic emission under uni-axial compression with the help of appropriate sensors and instrumentation.

Duplication 기법을 이용한 BPM의 10kHz DATA 다중 전송

박기수(G.U Park),이진원(J.W. Lee),김재명(J.M Kim),김성철(S.C. Kim),윤종철(J.C. Yoon),이재유(J.Y. Lee),조우성(W.S. Cho(PAL)) 대한전자공학회 2016 대한전자공학회 학술대회 Vol.2016 No.4

Sensitivity to Nuclear Data Libraries in the Physics Core Characteristics of Conceptual Thorium Breeders

V. Jagannathan,U. Pal,R. Karthikeyan,A. Srivastava,S. A. Khan 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

Nuclear data plays a vital role in the design of nuclear power reactors, especially for new conceptual ones where adequate validation base does not exist. For the continuity of ssion nuclear power beyond the present day power reactors operated in an open cycle mode, it is necessary to explore the possibility of reactor designs with higher conversion, rather higher breeding potential. In this context two reactor designs in the thermal and fast spectrum have been conceived having the above desired characteristics. The thermal version called `A Thorium Breeder Reactor' (ATBR) has conversion ratio higher by about 55% compared to an LWR [1]. The fast version called the `Fast Thorium Breeder Reactor' (FTBR) considers internal blanket or fissile breeding zones and hence has a reasonably high breeding ratio of at least 1.25 [2]. In this paper we present the variations in the salient physical core characteristics of the thermal version for three different sets of nuclear data libraries based on ENDFB/VI.8, ENDFB/VII and JEFF3.1 datasets [3].

Effect of In, Sb and Ga doping on the structure and vibrational modes of hydrothermally grown ZnO nanostructures

A. Escobedo-Morales,U. Pal 한국물리학회 2011 Current Applied Physics Vol.11 No.3

Effect of common optoelectronic dopants like In, Sb and Ga on the structure, morphology and vibrational modes of ZnO nanostructures has been studied systematically using scanning electron microscopy (SEM),X-ray diffraction (XRD), and Raman spectroscopy. While incorporation of Ga has no strong effect on the lattice parameters and crystallinity of ZnO nanostructures, In and Sb doping introduce considerable lattice distortion. Sb doping results an anisotropic distortion along the c axis of the ZnO unit cell. Several anomalous vibrational modes are induced due to incorporation of dopants into ZnO lattice. Origins of the observed anomalous modes are discussed.

PL and TL behaviors of Ag-doped SnO₂ nanoparticles: effects of thermal annealing and Ag concentration

Zeferino, R. Sanchez,Pal, U.,Melendrez, R,Flores, M. Barboza Techno-Press 2013 Advances in nano research Vol.1 No.4

In this article, we present the effects of Ag doping and after-growth thermal annealing on the photoluminescence (PL) and thermoluminescence (TL) behaviors of $SnO_2$ nanoparticles. $SnO_2$ nanoparticles of 4-7 nm size range containing different Ag contents were synthesized by hydrothermal process. It has been observed that the after-growth thermal annealing process enhances the crystallite size and stabilizes the TL emissions of $SnO_2$ nanostructures. Incorporated Ag probably occupies the interstitial sites of the $SnO_2$ lattice, affecting drastically their emission behaviors on thermal annealing. Both the TL response and dose-linearity of the $SnO_2$ nanoparticles improve on 1.0% Ag doping, and subsequent thermal annealing. However, a higher Ag content causes the formation of Ag clusters, reducing both the TL and PL responses of the nanoparticles.

Waveguiding behavior of VLS-grown one-dimensional Ga-doped In2O3 nanostructures

Jesús Alberto Ramos Ramón,U. Pal,David Maestre,Ana Cremades 한국물리학회 2018 Current Applied Physics Vol.18 No.7

Highly crystalline undoped and Ga-doped indium oxide nanorods with square-shaped faceted morphology were fabricated through the vapor-liquid-solid process at moderate temperature. Effects of Ga incorporation on the growth rate, morphology, and crystallinity of the nanostructures were evaluated by scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. Defect structure and waveguiding behavior of the 1-D In2O3 nanostructures have been studied using microRaman and micro photoluminescence spectroscopies. The appearance of several resonant modes superposed over the broad room temperature micro-photoluminescence spectra of the nanostructures demonstrates their waveguiding behaviors. While the pristine or undoped In2O3 nanostructures of 20–150 nm widths revealed Fabry-Pérot resonance modes, the Ga-incorporated nanostructures of 20–100 nm width revealed whispering gallery modes due to their smaller widths. The quality factor (Q) of the resonators was estimated to be about 20.86 and 188.79 for the pristine and Ga-incorporated nanostructures, respectively, indicating a huge enhancement due to Ga incorporation. The increment in the Q factor on Ga incorporation in In2O3 nanorods opens up the possibility of their utilization for the development of new optical transmitters and resonators, and fabrication of nanoscopic lasing devices.

Mesenchymal Stem Cells of Different Origin-Seeded Bioceramic Construct in Regeneration of Bone Defect in Rabbit

Swapan Kumar Maiti,M. U. Shivakumar,Divya Mohan,Naveen Kumar,Karam Pal Singh 한국조직공학과 재생의학회 2018 조직공학과 재생의학 Vol.15 No.4

BACKGROUND: Stem cell is currently playing a major role in the treatment of number of incurable diseases via transplantation therapy. The objective of this study was to determine the osteogenic potential of allogenic and xenogenic bone-derived MSC seeded on a hydroxyapatite (HA/TCP) bioceramic construct in critical size bone defect (CSD) in rabbits. METHODS: A 15 mm long radial osteotomy was performed unilaterally in thirty-six rabbits divided equally in six groups. Bone defects were filled with bioscaffold seeded with autologous, allogenic, ovine, canine BMSCs and cell free bioscaffold block in groups A, B, C, D and E respectively. An empty defect served as the control group. RESULTS: The radiological, histological and SEM observations depicted better and early signs of new bone formation and bridging bone/implant interfaces in the animals of group A followed by B. Both xenogenous MSC-HA/TCP construct also accelerated the healing of critical sized bone defect. There was no sign of any inflammatory reaction in the xenogenic composite scaffold group of animals confirmed their well acceptance by the host body. CONCLUSION: In vivo experiments in rabbit CSD model confirmed that autogenous, allogenous and xenogenous BMSC seeded on bioscaffold promoted faster healing of critical size defects. Hence, we may suggest that BMSCs are suitable for bone formation in fracture healing and non-union.

Red emitting Y2O3:Eu3+ nanophosphors with >80% down conversion efficiency

Jadhav, A. P.,Pawar, A. U.,Pal, U.,Kang, Y. S. Royal Society of Chemistry 2014 Journal of Materials Chemistry C Vol.2 No.3

Obtaining nanophosphors of a controlled size and shape with a high quantum efficiency is the current challenge for display and imaging technologies. Although the surface state induced luminescence quenching in nanophosphors may be compensated to some extent by incorporating activators like rare-earth ions, or by exploiting their quantum size effect, obtaining nanophosphors with quantum efficiencies as high as their bulk counterparts remains elusive. In the present article, we report on the synthesis of uniform Eu-doped Y2O3 nanoparticles, with an average size of 20-53 nm and a down conversion efficiency as high as 85%, using a simple chemical precipitation technique. Along with size control, the effects of Eu3+ content on their emission behaviors have been discussed. We believe the low-cost synthesis process of these nanoparticles will greatly enhance their application potential in optical display and bio-imaging technologies.

Study of microcellular injection-molded polypropylene/waste ground rubber tire powder blend

Xin, Z.X.,Zhang, Z.X.,Pal, K.,Byeon, J.U.,Lee, S.H.,Kim, J.K. Scientific and Technical Press ; Elsevier Science 2010 MATERIALS AND DESIGN Vol.31 No.1

Microcellular polypropylene/waste ground rubber tire powder blend processing was performed on an injection-molding machine with a chemical foaming agent. The molded samples produced based on the design of experiments (DOE) matrices were subjected to tensile testing and scanning electron microscope (SEM) analyses. Molding conditions and waste ground rubber tire (WGRT) powder have been found to have profound effects on the cell structures and mechanical properties of polypropylene (PP) and waste ground rubber tire powder composite samples. The result shows that microcellular PP/WGRT blend samples exhibit smaller cell size and higher cell density compare with polypropylene resin. Among the molding parameters studied, chemical foaming agent weight percentage has the most significant effect on cell size, cell density, and tensile strength. The results also suggest that tensile strength of microcellular PP/WGRT composites is sensitive to weight reduction, and skin thickness.

Evolution of ZnO nanostructures in sol–gel synthesis

J. Lee,A.J. Easteal,U. Pal,D. Bhattacharyya 한국물리학회 2009 Current Applied Physics Vol.9 No.4

Evolution of the microstructure and optical properties of ZnO nanoparticles in a mild sol–gel synthesis process is studied. The ZnO nanostructures were prepared by reacting zinc acetate dihydrate with NaOH in water at 50-60 ℃. Evolution of ZnO nanostructures with reaction time is studied using UV–Vis spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy techniques. During the process of Zn2+ hydroxylation, well defined rod-like crystals were formed within 15 min. Further hydroxylation leads to the formation of a gel-like structure within about 45 min. However, XRD, FT-IR and energy dispersive spectroscopy (EDS) confirmed that these initial products were zinc hydroxyl double salts (Zn-HDS), not ZnO. On ageing the reaction mixture, ZnO nanoparticles with wurtzite structure evolved. Evolution of the microstructure and optical properties of ZnO nanoparticles in a mild sol–gel synthesis process is studied. The ZnO nanostructures were prepared by reacting zinc acetate dihydrate with NaOH in water at 50-60 ℃. Evolution of ZnO nanostructures with reaction time is studied using UV–Vis spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy techniques. During the process of Zn2+ hydroxylation, well defined rod-like crystals were formed within 15 min. Further hydroxylation leads to the formation of a gel-like structure within about 45 min. However, XRD, FT-IR and energy dispersive spectroscopy (EDS) confirmed that these initial products were zinc hydroxyl double salts (Zn-HDS), not ZnO. On ageing the reaction mixture, ZnO nanoparticles with wurtzite structure evolved.