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Papers by Shivani Singh
Journal of Crystal Growth, 2010
Transparent crystalline fibers of $ 25 mm length and $ 1 mm diameter of KDP (0.3 and 0.4 mol%)dop... more Transparent crystalline fibers of $ 25 mm length and $ 1 mm diameter of KDP (0.3 and 0.4 mol%)doped L-arginine phosphate (LAP) were prepared by laser heated pedestal growth technique. The crystalline fibers were prepared with $ 5.4 W of CW CO 2 laser power, $ 7.7 cm/hr sample rodpushing speed and $ 19.4 cm/hr fiber pulling speed. The crystalline fibers were almost 100% transparent in 250-1200 nm region with cut-off frequency at 220 nm. Powder and single crystal XRD analysis led to the conclusion that KDP doping did not change the crystal structure of LAP. The calculations based on single crystal XRD data produced the structure of the KDP: LAP identical to undoped LAP. This observation is further confirmed by FTIR analysis. The presence of KDP in LAP was confirmed by energy dispersive X-ray analysis (EDX). The shifting and broadening of the photoluminescent emission also indicated KDP doping in LAP. Thermal behavior of crystalline fiber showed significant increase in the decomposing temperature of LAP on doping with KDP so as to make the melt growth of KDP: LAP easy.
Journal of Crystal Growth, 2010
In the past three decades, extensive theoretical and experimental investigations of the non-linea... more In the past three decades, extensive theoretical and experimental investigations of the non-linear optical (NLO) properties of materials have attracted much attention because of their potential applications in the emerging optoelectronic technology [1, 2]. Recently there have been extensive efforts to develop new organic, inorganic and semi-organic NLO crystals. Semi organic materials possess several advantages compared with the traditional inorganic NLO materials like ADP, KDP, KTP, such as large second harmonic conversion efficiency, birefringence and dispersion of refractive index, which are finding increasing use in the development of new photonic devices. In
American Journal of Orthodontics and Dentofacial Orthopedics
Introduction: The aims of this study were to analyze the stress distribution and displacement pat... more Introduction: The aims of this study were to analyze the stress distribution and displacement patterns that develop in an orthodontic miniscrew implant and its surrounding osseous structures for 2 implant materials under horizontal and torsional loading, with no ossseointegration. Methods: A numeric approach was adopted. The finite element method was used to determine the stress and displacement of the various components at a given time after miniscrew implant application, when, due to viscoelastic relaxation effects, the only remaining stress field was from the application of the orthodontic load. Results: Stress distribution was not significantly different between the 2 types of implant material. Increased stress values were located at the necks of the implants and the surrounding cortical bone. Bending of the titanium miniscrew was observed in the neck region under horizontal traction. Conclusions: The differences between the values of stress and displacement we obtained for the 2 types of miniscrew were too small to be clinically significant. Optimization of the miniscrew implant composed of the titanium alloy might be achieved by increasing the bulk (quantity) of the material in the neck region. The miniscrew implant can be immediately loaded and used for group movement of teeth.
Journal of Crystal Growth, 2010
Transparent crystalline fibers of $ 25 mm length and $ 1 mm diameter of KDP (0.3 and 0.4 mol%)dop... more Transparent crystalline fibers of $ 25 mm length and $ 1 mm diameter of KDP (0.3 and 0.4 mol%)doped L-arginine phosphate (LAP) were prepared by laser heated pedestal growth technique. The crystalline fibers were prepared with $ 5.4 W of CW CO 2 laser power, $ 7.7 cm/hr sample rodpushing speed and $ 19.4 cm/hr fiber pulling speed. The crystalline fibers were almost 100% transparent in 250-1200 nm region with cut-off frequency at 220 nm. Powder and single crystal XRD analysis led to the conclusion that KDP doping did not change the crystal structure of LAP. The calculations based on single crystal XRD data produced the structure of the KDP: LAP identical to undoped LAP. This observation is further confirmed by FTIR analysis. The presence of KDP in LAP was confirmed by energy dispersive X-ray analysis (EDX). The shifting and broadening of the photoluminescent emission also indicated KDP doping in LAP. Thermal behavior of crystalline fiber showed significant increase in the decomposing temperature of LAP on doping with KDP so as to make the melt growth of KDP: LAP easy.
Journal of Crystal Growth, 2010
In the past three decades, extensive theoretical and experimental investigations of the non-linea... more In the past three decades, extensive theoretical and experimental investigations of the non-linear optical (NLO) properties of materials have attracted much attention because of their potential applications in the emerging optoelectronic technology [1, 2]. Recently there have been extensive efforts to develop new organic, inorganic and semi-organic NLO crystals. Semi organic materials possess several advantages compared with the traditional inorganic NLO materials like ADP, KDP, KTP, such as large second harmonic conversion efficiency, birefringence and dispersion of refractive index, which are finding increasing use in the development of new photonic devices. In
American Journal of Orthodontics and Dentofacial Orthopedics
Introduction: The aims of this study were to analyze the stress distribution and displacement pat... more Introduction: The aims of this study were to analyze the stress distribution and displacement patterns that develop in an orthodontic miniscrew implant and its surrounding osseous structures for 2 implant materials under horizontal and torsional loading, with no ossseointegration. Methods: A numeric approach was adopted. The finite element method was used to determine the stress and displacement of the various components at a given time after miniscrew implant application, when, due to viscoelastic relaxation effects, the only remaining stress field was from the application of the orthodontic load. Results: Stress distribution was not significantly different between the 2 types of implant material. Increased stress values were located at the necks of the implants and the surrounding cortical bone. Bending of the titanium miniscrew was observed in the neck region under horizontal traction. Conclusions: The differences between the values of stress and displacement we obtained for the 2 types of miniscrew were too small to be clinically significant. Optimization of the miniscrew implant composed of the titanium alloy might be achieved by increasing the bulk (quantity) of the material in the neck region. The miniscrew implant can be immediately loaded and used for group movement of teeth.