In recent years, X-ray CT imaging of polymer gel dosimeter has been applied to direct measurement of 3D dose distributions. This work presents the dependence of PAGAT polymer gel dosimeter response to different beam dose rate using X-ray... more
In recent years, X-ray CT imaging of polymer gel dosimeter has been applied to direct measurement of 3D dose distributions. This work presents the dependence of PAGAT polymer gel dosimeter response to different beam dose rate using X-ray CT scanner as an evaluation tool. The normoxic PAGAT polymer gel was prepared on bench top and irradiated to different doses at different dose-rate ranging from 0.5 to 5 Gy/min. After irradiation the dosimeter samples were imaged with X-ray CT scanner using appropriate scanning protocol. The results showed that PAGAT gel dosimeter formulations investigated in this study has the smallest dose rate dependence and the change in dose sensitivity amounts to 2 % over the dose rate interval studied.
A potential method has emerged in the form of water-equivalent "3D gel dosimetry" using optical computed-tomography (optical-CT) which enables accurate, high resolution, 3D measurement of dose distributions associated with modern... more
A potential method has emerged in the form of water-equivalent "3D gel dosimetry" using optical computed-tomography (optical-CT) which enables accurate, high resolution, 3D measurement of dose distributions associated with modern radiation treatments.. Optical Cone Beam CT (CBCT) scanner plays a major role for Gel dosimeter readout and clinical radiation therapy as 3-Dimensional Radiation Dosimetry. The normoxic PAGAT (Polyacrylamide Gelatin and Tetrakis) gel is used as a dosimeter for this cone beam CT analysis due to its tissue equivalent behaviour. Applying a uniform background subtraction of open field intensity resulted in cone beam CT reconstructed attenuation coefficient for a PAGAT Gel Dosimeter.
Optical Computed Tomography has wide applications in the treatment of cancer. In continuation of this, an in-house Laser CT scanner has been built for "3D gel dosimetry". The Laser CT (LCT) scanner plays a major for Gel dosimeter or... more
Optical Computed Tomography has wide applications in the treatment of cancer. In continuation of this, an in-house Laser CT scanner has been built for "3D gel dosimetry". The Laser CT (LCT) scanner plays a major for Gel dosimeter or phantom readout and in clinical radiation therapy as a 3-Dimensional Radiation Dosimetry. A gel dosimeter which absorbs dose in a tissue-equivalent manner and allows the measurement of spatial distribution of the deposited dose is required. The normoxic PAGAT (Polyacrylamide Gelatin and Tetrakis) gel is used as a dosimeter for this analysis. When laser passes through this gel phantom, absorption and scattering takes place and combined to attenuation. The optical attenuation coefficient of the laser can be obtained by measuring its intensity after passing through the gel by means of a sensor. Reconstruction using Mat Lab algorithm provides 3D dose distribution.
The effect of La and Ti co-substitution on the structural, dielectric, magnetodielectric and ferroelectric properties of sol-gel synthesized Bi 1 À x La x Fe 1 À x Ti x O 3 (for x ¼0, 0.1 and 0.2) nanoparticles were investigated. Rietveld... more
The effect of La and Ti co-substitution on the structural, dielectric, magnetodielectric and ferroelectric properties of sol-gel synthesized Bi 1 À x La x Fe 1 À x Ti x O 3 (for x ¼0, 0.1 and 0.2) nanoparticles were investigated. Rietveld refinement of X-ray diffraction pattern confirmed the phase transition from rhom-bohedral (R3c) to orthorhombic (Pbnm) space group. XPS analysis revealed the existence of Fe as a single state in the co-substituted samples. Temperature dependent dielectric study confirmed that there is an anomaly at the vicinity of Neel temperature for all the compositions. All the co-substituted samples demonstrated a strong magnetodielectric response.
We prepared the Polyvinyl alcohol (PVA)/CdCl2 and PVA/Polyvinylpyrrolidone (PVP)/CdCl2 composites by solution blending known as the soft polymer ionic membrane (SPIM). The loading of CdCl2 divalent ions demonstrates an influence over the... more
We prepared the Polyvinyl alcohol (PVA)/CdCl2 and PVA/Polyvinylpyrrolidone (PVP)/CdCl2 composites by solution blending known as the soft polymer ionic membrane (SPIM). The loading of CdCl2 divalent ions demonstrates an influence over the electronic structure was confirmed by UV analysis. The bright divalent ionic morphology observed by scanning electron microscopy (SEM). The optimization of specific capacitance (Cp) and the dielectric constant disclosed as a function of an external DC bias potential. The trend of polarization was inversely proportional to the DC bias with the PVA system and directly to the PVP system. We disclosed the dielectric constant as a function of ionic loading. The optimized dielectric constant for various applications.
We demonstrated the synthesis and measurement of temperature dependent electrical resistivity of graphene oxide (GO) reinforced poly (3, 4 - ethylenedioxythiophene) - tetramethacrylate (PEDOTTMA)/Polymethylmethacrylate (PMMA) based... more
We demonstrated the synthesis and measurement of temperature dependent electrical resistivity of graphene oxide (GO) reinforced poly (3, 4 - ethylenedioxythiophene) - tetramethacrylate (PEDOTTMA)/Polymethylmethacrylate (PMMA) based nanocomposites. Negative temperature coefficient (NTC) was observed for 0.5, 1 % GO loading and the positive temperature coefficient (PTC) was observed for 1.5 and 2 % Go loading in the temperature (40 to 120 0C). The GO inducted nanocomposite perform as an excellent thermistor and suitable for electronic and sensor domain.
Composite films of Polyvinyl alcohol (PVA) mixed with Lead Titante Oxide (PbTiO3) were prepared. Dopant incorporated and DC bias induced electrical parameters were disclosed with respect to pure PVA film. The results demonstrate... more
Composite films of Polyvinyl alcohol (PVA) mixed with Lead Titante Oxide (PbTiO3) were prepared. Dopant incorporated and DC bias induced electrical parameters were disclosed with respect to pure PVA film. The results demonstrate dielectric polarization is not only directly proportional to PbTiO3% of dopant but also external DC bias potential at 30 C based on Maxwell Wagner theory. Hence these properties highly applicable as super-capacitor film and humidity sensor applications.
We have successfully demonstrated the effect of -irradiation on Polyacrylonitrile (PAN) gel in terms of admittance (Y), Susceptance (B) and Conductance (G). The trend of Y and B decreases by 297 μS and 138 μS respectively and conductance... more
We have successfully demonstrated the effect of -irradiation on Polyacrylonitrile (PAN) gel in terms of admittance (Y), Susceptance (B) and Conductance (G). The trend of Y and B decreases by 297 μS and 138 μS respectively and conductance (G) increases by 100 μS. Electrical mechanism associated with microstructure of PAN gel under external DC bias potential is the novelty of this work. External field stimuli responded due to delocalization of charge carriers. These properties are important as novel electronic material.
Polyvinyl alcohol (PVA) composed with polymethyl methacrylate (PMMA) polymer hydrogel was prepared by using boric acid as a cross-linking agent. The semicrystalline phase of composite gel was detected by X-ray diffraction tool. The... more
Polyvinyl alcohol (PVA) composed with polymethyl methacrylate (PMMA) polymer hydrogel was prepared by using boric acid as a cross-linking agent. The semicrystalline phase of composite gel was detected by X-ray diffraction tool. The occupied polymer PMMA morphology exhibits crosslinked alignment shown by scanning electron microscopy (SEM). The two-polymer system demonstrates an excellent dielectric property (with values, ε =590 for composite gel versus 400 compare to virgin PVA). The nonfluid media exhibit the impulse DC bias polarization. The basic principle of this work is to understand and control the electrical parameters under external stimuli (field) response by Impedance tool. In the biomedical field, this gel may be an excellent supporting media for sonographic as one of the best polar medium.
Graphene oxide (GO)-reinforced polyvinyl chloride (PVC) composite films were prepared by solution blending. The homogeneity of GO dispersion with PVC was confirmed by an optical microscope. Quality factor (Q-factor) as a function of... more
Graphene oxide (GO)-reinforced polyvinyl chloride (PVC) composite films were prepared by solution blending. The homogeneity of GO dispersion with PVC was confirmed by an optical microscope. Quality factor (Q-factor) as a function of temperature (40–150 C) was measured within a broadband frequency range of 50–35 MHz. The controlled GO loading demonstrates a crucial impact on the optimization of the Q-factor, resonance frequency (f0) and wide bandwidth. This nanocomposite may be well suited for electronic applications. The further development of GO-reinforced polymer nanocomposites based on an optimized Q-factor may result in a material for electromagnetic frequency radiation shields for radar and communication towers/devices.
The synthesis of nickel chloride (NiCl2)-mixed with polyvinyl alcohol films of 15–20 μm in thickness has been carried by solution blending technique. The dielectric properties of the films have been measured in the frequency range of 20... more
The synthesis of nickel chloride (NiCl2)-mixed with polyvinyl alcohol films of 15–20 μm in thickness has been carried by solution blending technique. The dielectric properties of the films have been measured in the frequency range of 20 Hz to 1 MHz under a positive bias potential in the range from 0 to 40 V. Improved electric characterization was demonstrated due to ionic incorporation of NiCl2. The low-frequency polarization was based on the Maxwell– Wagner interfacial model. Hence, this composite film may suggest as suitable electronic polar medium for versatile low-frequency applications.
In the present investigation, exfoliated graphite sheets were obtained from the thermo-chemical treatment of natural graphite flakes. In this process, the graphite expands almost 300 – 350 times of its original volume and takes the shape... more
In the present investigation, exfoliated graphite sheets were obtained from the thermo-chemical treatment of natural graphite flakes. In this process, the graphite expands almost 300 – 350 times of its original volume and takes the shape of worms. These worms can be pressed or rolled into any desired shape without any binder. The exfoliated graphite sheets show excellent electrical properties i.e. high dielectric constant (0 3 B 5 = 6.374x107) and comparatively low dielectric loss (tan 0 3 B 4 = 138) across the frequency in the range 50 Hz to 30 MHz and temperature in the range 40-300oC. The products developed from exfoliated graphite can have very good sealing applications in industrial areas, especially for gaskets in the automobile industries.
Polycarbonate (PC) and Poly (methyl methacrylate) blends were prepared by incorporating Al 2 O 3 into the polymer matrix using solution blending. The modified blends were characterized by X-ray diffraction, Thermogravimetric analysis, and... more
Polycarbonate (PC) and Poly (methyl methacrylate) blends were prepared by incorporating Al 2 O 3 into the polymer matrix using solution blending. The modified blends were characterized by X-ray diffraction, Thermogravimetric analysis, and Scanning electron microscopy. The crystalline to amorphous phase variation was confirmed by XRD with increase in the interplanar distance (d). TGA results indicate that the thermal stability of the modified blend was significantly improved as a function of alumina loading which may be due to interfacial interaction between the alumina particles and the polymers. Scanning electron microscopy studies reveal the presence of alumina particles resulting in plane surface morphology. The modified blends show very high dielectric constant value (10 5 –10 7) as a function of frequency (in the range 50 Hz–35 MHz) and temperature in the range (40–150 °C). The modified polymer blend demonstrate consistent polarization across the frequency band 50 Hz–10 kHz. The neutral aggregates formation due to higher concentration of alumina loading demonstrated an influence on AC conductivity. This investigation can be feasible for electronic and electrical engineering application as the dielectric medium.
In this work, polymer nanocomposites consisting of a poly(vinyl chloride) (PVC) and polyvinylidene fluoride (PVDF) polymer network with ZnO nanoparticles as a dopant were prepared by solution casting. An XRD study of the PVC/PVDF/ZnO... more
In this work, polymer nanocomposites consisting of a poly(vinyl chloride) (PVC) and polyvinylidene fluoride (PVDF) polymer network with ZnO nanoparticles as a dopant were prepared by solution casting. An XRD study of the PVC/PVDF/ZnO polymer nanocomposites shows predominantly sharp and high intensity peaks. However, the intensity and sharpness of the XRD peaks decreases with further increment in loading of ZnO (wt%), which reveals a proper intercalation of ZnO nanoparticles within the PVC/PVDF polymer system. Fourier transform infrared spectroscopy has been used to verify the chemical compositional change as a function of ZnO nanoparticle loading. TGA analysis clearly describes the thermal degradation of the pure polymer and polymer nanocomposites. The complex dielectric function, AC electrical conductivity and impedance spectra of these nanocomposites were investigated over the frequency range from 10 Hz to 35 MHz. These spectra were studied with respect to the Wagner − Maxwell − Sillars phenomenon in the low frequency region. Nyquist plots of the PVC/PVDF/ZnO nanocomposites were established from impedance measurements. The temperature-dependent DC ionic conductivity obtained from the Nyquist plots follows Arrhenius behaviour.
