The use of static light scattering for the structure analysis of radiosensitive polymer gels: a literature survey

Energy Technology Data Exchange (ETDEWEB)

Bussche, E Vanden [Department of Radiotherapy Nuclear Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent (Belgium); Deene, Y de [Department of Radiotherapy Nuclear Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent (Belgium); Dubruel, P [Polymer Material Research Group, Ghent University, Krijgslaan 281, 9000 Ghent (Belgium); Vergote, K [Department of Radiotherapy Nuclear Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent (Belgium); Schacht, E [Polymer Material Research Group, Ghent University, Krijgslaan 281, 9000 Ghent (Belgium); Wagter, C de [Department of Radiotherapy Nuclear Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent (Belgium)

2004-01-01

Static light scattering (SLS) could be a worthy technique to perform a structure analysis of the polymer structures inside radiation sensitive gels. The information obtained with SLS is a static characterization of the particle structures inside the gel. SLS will be combined with NMR relaxometry and NMR diffusion measurements, which deliver a hydrodynamic characterization of the microstructure of the gels.

Radiation sensitive polymers of oxygen-substituted maleimides and elements containing same

International Nuclear Information System (INIS)

Wilson, J.C.

1977-01-01

Radiation sensitive polymers comprising from about 1 to 100 mole % of a polymerized maleimide monomer consisting of a hydrocarbon group having from 2 to 20 carbon atoms, preferably a bridged hydrocarbon group having from 6 to 10 carbon atoms and from 0 to about 99 mole % of at least one additional polymerized ethylenically unsaturated monomer are described. The polymers are soluble in organic solvents, possess desirably high glass transition temperatures and are capable of undergoing a photochemical reaction to yield polymers having isocyanate and oxy-substituted cyclopropane moieties which are capable of crosslinking in the presence of active hydrogen-containing compounds. The polymers are useful in radiation sensitive compositions and elements containing same

Influence of solvent on the poly (acrylic acid)-oligo-(ethylene glycol) polymer gel electrolyte and the performance of quasi-solid-state dye-sensitized solar cells

International Nuclear Information System (INIS)

Wu, Jihuai; Lan, Zhang; Lin, Jianming; Huang, Miaoliang; Hao, Shancun; Fang, Leqing

2007-01-01

The influence of solvents on the property of poly (acrylic acid)-oligo-(ethylene glycol) polymer gel electrolyte and photovoltaic performance of quasi-solid-state dye-sensitized solar cells (DSSCs) were investigated. Solvents or mixed solvents with large donor number enhance the liquid electrolyte absorbency, which further influences the ionic conductivity of polymer gel electrolyte. A polymer gel electrolyte with ionic conductivity of 4.45 mS cm -1 was obtained by using poly (acrylic acid)-oligo-(ethylene glycol) as polymer matrix, and absorbing 30 vol.% N-methyl pyrrolidone and 70 vol.% γ-butyrolactone with 0.5 M NaI and 0.05 M I 2 . By using this polymer gel electrolyte coupling with 0.4 M pyridine additive, a quasi-solid-state dye-sensitized solar cell with conversion efficiency of 4.74% was obtained under irradiation of 100 mW cm -2 (AM 1.5)

Effect of pH grade on polymer-gel dosimeter and its brachytherapy application

International Nuclear Information System (INIS)

Spevacek, V.; Hrbacek, J.; Dvorak, P.; Cechak, T.; Novotny, J.

2003-01-01

To evaluate impact of pH grade on characteristics of polymer-gel dosimeter and its application in dose distribution verification in brachytherapy. A polymer-gel dosimeter based on radiation induced polymerization and crosslinking of acrylic monomers (acrylic acid, N,N' methylen-bis-acrylamide) was investigated with respect to its pH grade. pH grade of a dosimeter was varied by concentration of natrium hydroxide. Afterwards, dosimeter was split into several samples which were uniformly irradiated with Co-60 gamma rays. The range of doses applied was usually from 0 to 50 Gy with the main interest in region up to 20 Gy. Evaluation of dosimeter dose response was performed using MRI (T2). Dose response curves obtained were evaluated with respect to pH grade as a parameter. In parallel, there was studied temperature resistance (melting temperature) of gels with various pH grade. pH grade modified polymer-gel dosimeter was then used to compare dose distribution calculated with brachytherapy treatment planning system for simple irradiation geometry with Ir-192 HDR source. Additionaly, Monte Carlo calculated data were also included in the brachytherapy study. There was observed effect of pH grade on dose-response curve parameters (slope of linear fit, background response, linear range and maximum measurable dose). In general, the lower pH grade the higher sensitivity. Another positive effect of decreased pH grade is significantly higher maximum measurable dose. Maximum melting temperature of a gel was observed with pH grade between 3.5 and 4. For both higher and lower pH grades the melting temperature was lower. Using pH modified polymer-gel dosimeter simple brachytherapy dose distribution was measured and compared with calculated and Monte Carlo simulated data. There was observed strong dependence of dose-response relationship on pH grade of polymer-gel dosimeter resulting in significant improvement of dosimeter characteristics, namely sensitivity, applicable range of

Investigation of vacuum pumping on the dose response of the MAGAS normoxic polymer gel dosimeter

International Nuclear Information System (INIS)

Venning, AJ.; Canberra Hospital, Canberra; University of Sydney, Sydney; Mather, ML.; Baldock, C.

2005-01-01

The effect of vacuum pumping on the dose response of the MAGAS polymer gel dosimeter has been investigated. A delay of several days post-manufacture before irradiation was previously necessary due to the slow oxygen scavenging of ascorbic acid. The MAGAS polymer gel dosimeter was vacuum pumped before gelation to remove dissolved oxygen. The MAGAS polymer gel dosimeter was poured into glass screw-top vials, which were irradiated at various times, post-manufacture to a range of doses. Magnetic resonance imaging techniques were used to determine the R2-dose response and /?2-dose sensitivity of the MAGAS polymer gel. The results were compared with a control batch of MAGAS polymer gel that was not vacuum pumped. It was shown that vacuum pumping on the MAGAS polymer gel solution immediately prior to sealing in glass screw-top vials initially increases the R2-dose response and R2-dose sensitivity of the dosimeter. An increase in the .R2-dose response and i?2-dose sensitivity was observed with increasing time between manufacture and irradiation. Over the range of post-manufacture irradiation times investigated, the greatest i?2-dose response and if 2 -dose sensitivity occurred at 96 hours

Cosolvent-free polymer gel dosimeters with improved dose sensitivity and resolution for x-ray CT dose response

Energy Technology Data Exchange (ETDEWEB)

Chain, J N M; McAuley, K B [Department of Chemical Engineering, Queen' s University, Kingston, K7L 3N6 (Canada); Jirasek, A [Department of Physics and Astronomy, University of Victoria, Victoria, V8W 3P6 (Canada); Schreiner, L J, E-mail: kim.mcauley@chee.queensu.ca [Cancer Centre of Southeastern Ontario, Kingston, K7L 5P9 (Canada)

2011-04-07

This study reports new N-isopropylacrylamide (NIPAM) polymer gel recipes with increased dose sensitivity and improved dose resolution for x-ray CT readout. NIPAM can be used to increase the solubility of N, N'-methylenebisacrylamide (Bis) in aqueous solutions from approximately 3% to 5.5% by weight, enabling the manufacture of dosimeters containing up to 19.5%T, which is the total concentration of NIPAM and Bis by weight. Gelatin is shown to have a mild influence on dose sensitivity when gels are imaged using x-ray CT, and a stronger influence when gels are imaged optically. Phantoms that contain only 3% gelatin and 5 mM tetrakis hydroxymethyl phosphonium chloride are sufficiently stiff for dosimetry applications. The best cosolvent-free gel formulation has a dose sensitivity in the linear range ({approx}0.88 H Gy{sup -1}) that is a small improvement compared to the best NIPAM-based gels that incorporate isopropanol as a cosolvent ({approx}0.80 H Gy{sup -1}). This new gel formulation results in enhanced dose resolution ({approx}0.052 Gy) for x-ray CT readout, making clinical applications of this imaging modality more feasible.

Cosolvent-free polymer gel dosimeters with improved dose sensitivity and resolution for x-ray CT dose response

International Nuclear Information System (INIS)

Chain, J N M; McAuley, K B; Jirasek, A; Schreiner, L J

2011-01-01

This study reports new N-isopropylacrylamide (NIPAM) polymer gel recipes with increased dose sensitivity and improved dose resolution for x-ray CT readout. NIPAM can be used to increase the solubility of N, N'-methylenebisacrylamide (Bis) in aqueous solutions from approximately 3% to 5.5% by weight, enabling the manufacture of dosimeters containing up to 19.5%T, which is the total concentration of NIPAM and Bis by weight. Gelatin is shown to have a mild influence on dose sensitivity when gels are imaged using x-ray CT, and a stronger influence when gels are imaged optically. Phantoms that contain only 3% gelatin and 5 mM tetrakis hydroxymethyl phosphonium chloride are sufficiently stiff for dosimetry applications. The best cosolvent-free gel formulation has a dose sensitivity in the linear range (∼0.88 H Gy -1 ) that is a small improvement compared to the best NIPAM-based gels that incorporate isopropanol as a cosolvent (∼0.80 H Gy -1 ). This new gel formulation results in enhanced dose resolution (∼0.052 Gy) for x-ray CT readout, making clinical applications of this imaging modality more feasible.

Gel polymer electrolytes for batteries

Science.gov (United States)

Balsara, Nitash Pervez; Eitouni, Hany Basam; Gur, Ilan; Singh, Mohit; Hudson, William

2014-11-18

Nanostructured gel polymer electrolytes that have both high ionic conductivity and high mechanical strength are disclosed. The electrolytes have at least two domains--one domain contains an ionically-conductive gel polymer and the other domain contains a rigid polymer that provides structure for the electrolyte. The domains are formed by block copolymers. The first block provides a polymer matrix that may or may not be conductive on by itself, but that can soak up a liquid electrolyte, thereby making a gel. An exemplary nanostructured gel polymer electrolyte has an ionic conductivity of at least 1.times.10.sup.-4 S cm.sup.-1 at 25.degree. C.

Polymer gels and networks

National Research Council Canada - National Science Library

Osada, Yoshihito; Khokhlov, A. R

2002-01-01

... or magnetic field, etc.). It was realized that not only can polymer gels absorb and hold a considerable volume of liquids, but they can also be forced to expel the absorbed liquid in a controlled manner. Of particular interest are hydrogels, i.e., polymer gels, which swell extensively in water. The most common hydrogels are polyelectrolyte gels: ...

Polymer gel dosimeter based on itaconic acid

International Nuclear Information System (INIS)

Mattea, Facundo; Chacón, David

2015-01-01

A new polymeric dosimeter based on itaconic acid and N, N’-methylenebisacrylamide was studied. The preparation method, compositions of monomer and crosslinking agent and the presence of oxygen in the dosimetric system were analyzed. The resulting materials were irradiated with an X-ray tube at 158 cGy/min, 226 cGy min and 298 cGy/min with doses up to 1000 Gy. The dosimeters presented a linear response in the dose range 75–1000 Gy, sensitivities of 0.037 1/Gy at 298 cGy/min and an increase in the sensitivity with lower dose rates. One of the most relevant outcomes in this study was obtaining different monomer to crosslinker inclusion in the formed gel for the dosimeters where oxygen was purged during the preparation method. This effect has not been reported in other typical dosimeters and could be attributed to the large differences in the reactivity among these species. - Highlights: • A novel polymer gel dosimeters based on itaconic acid is presented and characterized. • The typical linear trend of the dose behavior in a specific dose range was found. • Different gel structures were formed when oxygen and an antioxidant were present. • Absorbed dose is univocally correlated with optic absorbance and Raman spectroscopy. • Itaconic acid appears as a reliable radiation dosimeter that may be further improved.

Radiation processing of biodegradable polymer hydrogel from cellulose derivatives

International Nuclear Information System (INIS)

Wach, Radoslaw A.; Mitomo, Hiroshi; Yoshii, Fumio; Kume, Tamikazu

2001-01-01

The effects of high-energy radiation on ethers of cellulose: carboxymethyl-, hydroxypropyl- and hydroxyethylcellulose have been investigated. Polymers were irradiated in solid state and aqueous solution at various concentrations. Degree of substitution (DS), the concentration in the solution and irradiation conditions had a significant impact on the obtained products. Irradiation of polymers in solid and in diluted solution resulted in their degradation. A novel hydrogels of such natural polymers were synthesized, without using any additives, by irradiation at high concentration. It was found that high DS of CMC promoted crosslinking and, for all of the ethers, the gel formation occurred easier for more concentrated solutions. Paste-like form of the initial material, when water plasticised the bulk of polymer mass, along with the high dose rate and preventing oxygen accessibility to the sample during irradiation were favorable for hydrogel preparation. Up to 95% of gel fraction was obtained from 50 and 60% CMC solutions irradiated by gamma rays or by a beam of accelerated electrons (EB). The other polymers were more sensitive to the dose rate and formed gels with higher gel fraction while processed by EB. Moreover, polymers (except CMC) treated by gamma rays were susceptible to degradation after application of a dose over 50-100 kGy. The presence of oxygen in the system during irradiation limited a gel content and was prone to easier degradation of already formed gel. Produced hydrogels swelled markedly by absorption when paced in the solvent. Crosslinked polymers showed susceptibility to degradation by cellulase enzyme and by the action of microorganisms in compost or under natural conditions in soil thus could be included into the group of biodegradable materials. (author)

Radiation processing of biodegradable polymer hydrogel from cellulose derivatives

Energy Technology Data Exchange (ETDEWEB)

Wach, Radoslaw A.; Mitomo, Hiroshi [Gunma Univ., Faculty of Engineering, Department of Biological and Chemical Engineering, Kiryu, Gunma (Japan); Yoshii, Fumio; Kume, Tamikazu [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

2001-03-01

The effects of high-energy radiation on ethers of cellulose: carboxymethyl-, hydroxypropyl- and hydroxyethylcellulose have been investigated. Polymers were irradiated in solid state and aqueous solution at various concentrations. Degree of substitution (DS), the concentration in the solution and irradiation conditions had a significant impact on the obtained products. Irradiation of polymers in solid and in diluted solution resulted in their degradation. A novel hydrogels of such natural polymers were synthesized, without using any additives, by irradiation at high concentration. It was found that high DS of CMC promoted crosslinking and, for all of the ethers, the gel formation occurred easier for more concentrated solutions. Paste-like form of the initial material, when water plasticised the bulk of polymer mass, along with the high dose rate and preventing oxygen accessibility to the sample during irradiation were favorable for hydrogel preparation. Up to 95% of gel fraction was obtained from 50 and 60% CMC solutions irradiated by gamma rays or by a beam of accelerated electrons (EB). The other polymers were more sensitive to the dose rate and formed gels with higher gel fraction while processed by EB. Moreover, polymers (except CMC) treated by gamma rays were susceptible to degradation after application of a dose over 50-100 kGy. The presence of oxygen in the system during irradiation limited a gel content and was prone to easier degradation of already formed gel. Produced hydrogels swelled markedly by absorption when paced in the solvent. Crosslinked polymers showed susceptibility to degradation by cellulase enzyme and by the action of microorganisms in compost or under natural conditions in soil thus could be included into the group of biodegradable materials. (author)

The polymer gel electrolyte based on poly(methyl methacrylate) and its application in quasi-solid-state dye-sensitized solar cells

International Nuclear Information System (INIS)

Yang Hongxun; Huang Miaoliang; Wu Jihuai; Lan Zhang; Hao Sancun; Lin Jianming

2008-01-01

Using poly(methyl methacrylate) as polymer host, ethylene carbonate, 1,2-propanediol carbonate and dimethyl carbonate as organic mixture solvents, sodium iodide and iodine as source of I - /I 3 - , a polymer gel electrolyte PMMA-EC/PC/DMC-NaI/I 2 with ionic conductivity of 6.89 mS cm -1 was prepared. Based on the polymer gel electrolyte, a quasi-solid-state dye-sensitized solar cell (DSSC) was fabricated. The quasi-solid-state DSSC possessed a good long-term stability and a light-to-electrical energy conversion efficiency of 4.78% under irradiation of 100 mW cm -2 simulated sunlight, which is almost equal to that of DSSC with a liquid electrolyte

Creation of Dosimetric Verification for Implementation of Intensity Modulated Radiation Therapy (IMRT) Validates Using Polymer Gel

International Nuclear Information System (INIS)

Mansour, M.Sh.E.

2015-01-01

Polymer gel dosimeter is a technique that has the ability to map absorbed radiation dose distributions in three dimensions (3D) with high spatial resolution, it offers a number of advantages over traditional dosimeters such as ionization chambers, thermo luminescent dosimeters (TLD) and radiographic film. These gels are reproducible in response and stable 0 n post-irradiation. It is used as the monomer N-iso propyl acryl amide (NIPAM) and N, N- methylene bis acryl amide (Bis) as the cross linker. A historical overview of gel dosimeter was discussed in detail, inside the theses this case; nearly all data met the expected measurement error of 5 % of the maximum dose (50 c Gy). Relative errors were determined to decrease from 25 % at a 2 Gy irradiation to 9.2% for a 10 Gy irradiation The NIPAM polymer gel dosimeter system proved to be an invaluable method for the quantification of the 3-D dose distribution provided by IMRT. A measurement error of less than 5% was achieved. Toxicity and uncertain response to particular environmental characteristics (i.e., temperature and aging) upon the gel are of important concern about the use of the gel at this time. A PAG gel dosimeter is a method verifying dose delivered for prostate cancer radiotherapy treatment, which has been evaluated in this work. A comparison of DVH for PTV between the two treatment plans was verified experimentally. MRI response, the possibility was demonstrated of manufacturing gel dosimeters suitable for 3D dosimeter in the dose range. The results show that IMRT technique not only provides a better conformal dose to the prostate target volume than conventional Seven-field technique, but also reduces doses to the surrounding normal tissues, The aim of this study was to investigate the basic characteristics of the modified gel dosimeter such as temperature effects, magnetic field strength, Ph, aging, energy and dose rate dependence This includes studies of relaxation time dose response, and stability of the

Dosimetric evaluation of a novel polymer gel dosimeter for proton therapy

Energy Technology Data Exchange (ETDEWEB)

Zeidan, O. A.; Sriprisan, S. I.; Lopatiuk-Tirpak, O.; Kupelian, P. A.; Meeks, S. L.; Hsi, W. C.; Li, Z.; Palta, J. R.; Maryanski, M. J. [M. D. Anderson Cancer Center Orlando, Orlando, Florida 32806 (United States); University of Florida Proton Therapy Institute, Jacksonville, Florida 32206 (United States); MGS Research, Inc., Madison, Connecticut 06443 (United States)

2010-05-15

Purpose: The aim of this study is to evaluate the dosimetric performance of a newly developed proton-sensitive polymer gel formulation for proton therapy dosimetry. Methods: Using passive scattered modulated and nonmodulated proton beams, the dose response of the gel was assessed. A next-generation optical CT scanner is used as the readout mechanism of the radiation-induced absorbance in the gel medium. Comparison of relative dose profiles in the gel to ion chamber profiles in water is performed. A simple and easily reproducible calibration protocol is established for routine gel batch calibrations. Relative stopping power ratio measurement of the gel medium was performed to ensure accurate water-equivalent depth dose scaling. Measured dose distributions in the gel were compared to treatment planning system for benchmark irradiations and quality of agreement is assessed using clinically relevant gamma index criteria. Results: The dosimetric response of the gel was mapped up to 600 cGy using an electron-based calibration technique. Excellent dosimetric agreement is observed between ion chamber data and gel. The most notable result of this work is the fact that this gel has no observed dose quenching in the Bragg peak region. Quantitative dose distribution comparisons to treatment planning system calculations show that most (>97%) of the gel dose maps pass the 3%/3 mm gamma criterion. Conclusions: This study shows that the new proton-sensitive gel dosimeter is capable of reproducing ion chamber dose data for modulated and nonmodulated Bragg peak beams with different clinical beam energies. The findings suggest that the gel dosimeter can be used as QA tool for millimeter range verification of proton beam deliveries in the dosimeter medium.

Dosimetric evaluation of a novel polymer gel dosimeter for proton therapy

International Nuclear Information System (INIS)

Zeidan, O. A.; Sriprisan, S. I.; Lopatiuk-Tirpak, O.; Kupelian, P. A.; Meeks, S. L.; Hsi, W. C.; Li, Z.; Palta, J. R.; Maryanski, M. J.

2010-01-01

Purpose: The aim of this study is to evaluate the dosimetric performance of a newly developed proton-sensitive polymer gel formulation for proton therapy dosimetry. Methods: Using passive scattered modulated and nonmodulated proton beams, the dose response of the gel was assessed. A next-generation optical CT scanner is used as the readout mechanism of the radiation-induced absorbance in the gel medium. Comparison of relative dose profiles in the gel to ion chamber profiles in water is performed. A simple and easily reproducible calibration protocol is established for routine gel batch calibrations. Relative stopping power ratio measurement of the gel medium was performed to ensure accurate water-equivalent depth dose scaling. Measured dose distributions in the gel were compared to treatment planning system for benchmark irradiations and quality of agreement is assessed using clinically relevant gamma index criteria. Results: The dosimetric response of the gel was mapped up to 600 cGy using an electron-based calibration technique. Excellent dosimetric agreement is observed between ion chamber data and gel. The most notable result of this work is the fact that this gel has no observed dose quenching in the Bragg peak region. Quantitative dose distribution comparisons to treatment planning system calculations show that most (>97%) of the gel dose maps pass the 3%/3 mm gamma criterion. Conclusions: This study shows that the new proton-sensitive gel dosimeter is capable of reproducing ion chamber dose data for modulated and nonmodulated Bragg peak beams with different clinical beam energies. The findings suggest that the gel dosimeter can be used as QA tool for millimeter range verification of proton beam deliveries in the dosimeter medium.

Polymer gel dosimetry for synchrotron stereotactic radiotherapy and iodine dose-enhancement measurements

International Nuclear Information System (INIS)

Boudou, C; Tropres, I; Rousseau, J; Lamalle, L; Adam, J F; Esteve, F; Elleaume, H

2007-01-01

Synchrotron stereotactic radiotherapy (SSR) is a radiotherapy technique that makes use of the interactions of monochromatic low energy x-rays with high atomic number (Z) elements. An important dose-enhancement can be obtained if the target volume has been loaded with a sufficient amount of a high-Z element, such as iodine. In this study, we compare experimental dose measurements, obtained with normoxic polymer gel (nPAG), with Monte Carlo computations. Gels were irradiated within an anthropomorphic head phantom and were read out by magnetic resonance imaging. The dose-enhancement due to the presence of iodine in the gel (iodine concentration: 5 and 10 mg ml -1 ) was measured at two radiation energies (35 and 80 keV) and was compared to the calculated factors. nPAG dosimetry was shown to be efficient for measuring the sharp dose gradients produced by SSR. The agreement between 3D gel dosimetry and calculated dose distributions was found to be within 4% of the dose difference criterion and a distance to agreement of 2.1 mm for 80% of the voxels. Polymer gel doped with iodine exhibited higher sensitivity, in good agreement with the calculated iodine-dose enhancement. We demonstrate in this preliminary study that iodine-doped nPAG could be used for measuring in situ dose distributions for iodine-enhanced SSR treatment

Phthaloylchitosan-Based Gel Polymer Electrolytes for Efficient Dye-Sensitized Solar Cells

Directory of Open Access Journals (Sweden)

S. N. F. Yusuf

2014-01-01

Full Text Available Phthaloylchitosan-based gel polymer electrolytes were prepared with tetrapropylammonium iodide, Pr4NI, as the salt and optimized for conductivity. The electrolyte with the composition of 15.7 wt.% phthaloylchitosan, 31.7 wt.% ethylene carbonate (EC, 3.17 wt.% propylene carbonate (PC, 19.0 wt.% of Pr4NI, and 1.9 wt.% iodine exhibits the highest room temperature ionic conductivity of 5.27 × 10−3 S cm−1. The dye-sensitized solar cell (DSSC fabricated with this electrolyte exhibits an efficiency of 3.5% with JSC of 7.38 mA cm−2, VOC of 0.72 V, and fill factor of 0.66. When various amounts of lithium iodide (LiI were added to the optimized gel electrolyte, the overall conductivity is observed to decrease. However, the efficiency of the DSSC increases to a maximum value of 3.71% when salt ratio of Pr4NI : LiI is 2 : 1. This cell has JSC, VOC and fill factor of 7.25 mA cm−2, 0.77 V and 0.67, respectively.

Preliminary investigation of PAGAT polymer gel radionuclide dosimetry of Tc-99m

Science.gov (United States)

Braun, Kelly; Bailey, Dale; Hill, Brendan; Baldock, Clive

2009-05-01

PAGAT polymer gel was investigated as a suitable dosimeter materials for measuring absorbed dose from the unsealed source radionuclide Tc-99m. Differing amounts of Tc-99m over the range of 25-5000 MBq were introduced into a normoxic polymer gel mixture (PAGAT) in sealed nitrogen-filled P6 glass vials. After irradiation the gels were evaluated using MRI more than 48 hours after preparation to allow for radioactive decay. The dose delivered to the vial was also calculated empirically. R2 versus total activity curves were obtained over a number of experiments and these were used to evaluate the relationship between the amount of gel polymerization and the dose deposited by the radionuclide. A linear response up to 1000 MBq (corresponding to 20Gy) was displayed and was still behaving monotonically at 5000 MBq. Polymer gels offer the potential to measure radiation dose three-dimensionally using MRI.

Radiation crosslinking of polymer materials and its functional properties

International Nuclear Information System (INIS)

Yoshii, Fumio

2006-01-01

It was found out that radiation crosslinking of biodegradable polymer such as poly (butylene succinate, PBS) and poly(ε-caprolactone, PCL) could be achieved by radiation in the presence of small amount of trimethallyl isocyanurate (TMAIC) or 1% triallyl isocyanurate (TAIC). Such modification is very effective to improve heat resistance for PBS and PCL. Poly (lactic acid, PLA) undergoes crosslinking effectively with 3% TAIC by radiation. Outstanding feature of these polymers is their biodegradability even after crosslinking. Radiation crosslinking of polysaccharide derivatives such as carboxymethyl-cellulose (CMC) is also achieved in aqueous solution at high concentration (paste-like state). The crosslinking behavior was largely affected by the degree of substitution (DS) and polymer concentration. After removal of water the dry CMC gel is used as water absorbent material. This dry gel is the most effective for removal of large amounts of water from organic wastes, resulting in the acceleration of their fermentation. Measurement of swelling ratio of the dry CMC gel in 0.9% NaCl aqueous solution was carried out to expand application fields for this material. Radiation crosslinked poly (vinyl alcohol) hydrogel was successfully commercialized from July 2004 as wound dressing for accelerated healing. Furthermore, this material was also used as gel protector to prevent shore sore and was further commercialized. (author)

Dosimetric characteristics of PASSAG as a new polymer gel dosimeter with negligible toxicity

Science.gov (United States)

Farhood, Bagher; Abtahi, Seyed Mohammad Mahdi; Geraily, Ghazale; Ghorbani, Mehdi; Mahdavi, Seied Rabi; Zahmatkesh, Mohammad Hasan

2018-06-01

Despite many advantages of polymer gel dosimeters, their clinical use is only not realized now. Toxicity of polymer gel dosimeters can be considered as one of their main limitations for use in routine clinical applications. In the current study, a new polymer gel dosimeter is introduced with negligible toxicity. For this purpose, 2-Acrylamido-2-Methy-1-PropaneSulfonic acid (AMPS) sodium salt monomer was replaced instead of acrylamide monomer used in PAGAT gel dosimeter by using %6 T and %50 C to the gel formula and the new formulation is called PASSAG (Poly AMPS Sodium Salt and Gelatin) polymer gel dosimeter. The irradiation of gel dosimeters was carried out using a Co-60 therapy machine. MRI technique was used to quantify the dose responses of the PASSAG gel dosimeter. Then, the MRI responses (R2) of the gel dosimeter was analyzed at different dose values, post-irradiation times, and scanning temperatures. The results showed that the new gel formulation has a negligible toxicity and it is also eco-friendly. In addition, carcinogenicity and genetic toxicity tests are negative for the monomer used in PASSAG. The radiological properties of PASSAG gel dosimeter showed that this substance can be considered as a soft tissue/water equivalent material. Furthermore, dosimetric evaluation of the new polymer gel dosimeter revealed an excellent linear R2-dose response in the evaluated dose range (0-15 Gy). The R2-dose sensitivity and dose resolution of PASSAG gel dosimeter were 0.081 s-1Gy-1 (in 0-15 Gy dose range) and 1 Gy (in 0-10 Gy dose range), respectively. Moreover, it was shown that the R2-dose sensitivity and dose resolution of the new gel dosimeter improves over time after irradiation. It was also found that the R2 response of the PASSAG gel dosimeter has less dependency to the 18, 20, and 24 °C scanning temperature in comparison to that of room temperature (22 °C).

Sensitivity calibration procedures in optical-CT scanning of BANG 3 polymer gel dosimeters

Energy Technology Data Exchange (ETDEWEB)

Xu, Y.; Wuu, Cheng-Shie; Maryanski, Marek J. [Department of Radiation Oncology, Columbia University, New York, New York 10032 (United States); Department of Radiation Oncology, Columbia University, New York, New York 10032 and MGS Research Inc., Madison, Connecticut 06443 (United States)

2010-02-15

The dose response of the BANG 3 polymer gel dosimeter (MGS Research Inc., Madison, CT) was studied using the OCTOPUS laser CT scanner (MGS Research Inc., Madison, CT). Six 17 cm diameter and 12 cm high Barex cylinders, and 18 small glass vials were used to house the gel. The gel phantoms were irradiated with 6 and 10 MV photons, as well as 12 and 16 MeV electrons using a Varian Clinac 2100EX. Three calibration methods were used to obtain the dose response curves: (a) Optical density measurements on the 18 glass vials irradiated with graded doses from 0 to 4 Gy using 6 or 10 MV large field irradiations; (b) optical-CT scanning of Barex cylinders irradiated with graded doses (0.5, 1, 1.5, and 2 Gy) from four adjacent 4x4 cm{sup 2} photon fields or 6x6 cm{sup 2} electron fields; and (c) percent depth dose (PDD) comparison of optical-CT scans with ion chamber measurements for 6x6 cm{sup 2}, 12 and 16 MeV electron fields. The dose response of the BANG 3 gel was found to be linear and energy independent within the uncertainties of the experimental methods (about 3%). The slopes of the linearly fitted dose response curves (dose sensitivities) from the four field irradiations (0.0752{+-}3%, 0.0756{+-}3%, 0.0767{+-}3%, and 0.0759{+-}3% cm{sup -1} Gy{sup -1}) and the PDD matching methods (0.0768{+-}3% and 0.0761{+-}3% cm{sup -1} Gy{sup -1}) agree within 2.2%, indicating a good reproducibility of the gel dose response within phantoms of the same geometry. The dose sensitivities from the glass vial approach are different from those of the cylindrical Barex phantoms by more than 30%, owing probably to the difference in temperature inside the two types of phantoms during gel formation and irradiation, and possible oxygen contamination of the glass vial walls. The dose response curve obtained from the PDD matching approach with 16 MeV electron field was used to calibrate the gel phantom irradiated with the 12 MeV, 6x6 cm{sup 2} electron field. Three-dimensional dose distributions

Coordination Polymer Gels by Electron Beam

Energy Technology Data Exchange (ETDEWEB)

Lee, Ji Ha; Cho, Young Je; Jung, Jong Hwa [Gyeongsang National Univ., Jinju (Korea, Republic of)

2011-07-01

Hydrogenation of a pyridine derivative possessing tetrazole moieties as end groups, without long alkyl chain groups, results in the formation of a Mg(NO{sub 3}){sub 2} coordination polymer gel. The polymer exhibits a strong fluorescence enhancement upon gel formation. 1 can also be gloated with a variety of magnesium anions such as SO{sub 4}{sup 2-}, NO{sub 3}{sup -}, Cl{sup -}, Br{sup -} and I{sup -}, indicating that the coordination polymer gel formation of 1 does not strongly depends on anions. The Seam and ABM images of Mg{sup 2+} coordination polymer gel 1 display a flabbier network with several micrometers long, widths in the range 60-70 nm and thicknesses of about 3 nm. In addition, photophysical studies show that the hydrogel exhibits a typical {pi}-{pi} transition and gives rise to high fluorescence behavior. The coordination polymer hydrogel exhibits viscoelastic behavior as evidenced from the rheological studies.

Radiation synthesis of functionalising polymer and creation of composition materials on their basis

International Nuclear Information System (INIS)

Mun, G.A.; Nurkeeva, Z.S.; Akhmetkalieva, G.T.; Urkimbaeva, P.I.; Park, L.K.; Lyssukhin, S.N.; Chakrov, P.V.

2005-01-01

Full text: Hydrogels are three-dimensional crosslinked hydrophilic polymers capable of swelling in water and retaining possibly huge volumes of water in the swollen state. The ability of polymer gels to undergo substantial swelling and collapse, as a function of their environment is one of the most remarkable properties of these materials. By this reason such polymer hydrogels belong to so-called 'intelligent', 'smart' or stimuli-responsive materials. The phenomenon of gel volume transitions, which can be induced by temperature, pH, ionic environment and electric fields, has prompted researchers to investigate gels as potential sensors, force actuators, controllable membranes for separations, and modulators for delivery of drugs and other molecules. One of the most perspective applications of stimuli-responsive hydrogels is the designing of controlled drug delivery devices for medicine. In particular, so-called thermo-responsible hydrogels, which undergo a volume phase transition in an aqueous environment induced by a change in temperature, are the most interesting class of stimuli-responsive polymers. It should be noted that all such polymers were obtained usually by homo polymerization of amphiphilic monomers which have hydrophilic and hydrophobic fragments in their structure simultaneously. We used another approach for synthesis of thermo sensitive polymers of linear and cross-linked structure. This approach includes radiation copolymerization of monomers having significant difference in hydrophobic/hydrophilic balance. Some of thermo-sensitive hydrogels and water-soluble polymers were obtained by copolymerization of the following monomeric pairs: vinyl ether of ethyleneglycol (VEEG)-vinyl butyl ether (VBE), VEEG-vinyl isobutyl ether, vinyl ether of diethyleneglycol-VBE, VEEG-hydroxyethylmethacrylate (HEMA), hydroxyethylacrylate (HEA)-HEMA, HEA- butylacrylate, HEA-methylacrylate. The synthesis regularities have been studied. The linear copolymers show lower

Radiation crosslinking of polymer materials

International Nuclear Information System (INIS)

Yoshii, Fumio

2004-01-01

It was found that some polyfunctional monomers (PFM) like triallyl isocyanurate (TAIC) and trimethallyl isocyanurate (TMAIC) when incorporated at low concentrations, are effective for promotion of crosslinking of biodegradable polymers such as polycaprolactone (PCL), poly(butylene succinate-co-adipate) (PBS) and poly(lactic acid) (PLA). PFM are kneaded with biodegradable polymers at molten condition before irradiation. Radiation crosslinking of PBS and PCL with 1% TAIC gave gel fractions of 80% at 20 kGy. This crosslinking is effective to improve deformation of biodegradable polymers at high temperature. The irradiated materials retained their biodegradability even after crosslinking when subjected to soil burial test. Irradiation at molten state (melting temperature, 340degC) led to crosslinking structures for polytetrafluoroethylene (PTFE). Crosslinked PTFE forms transparent films with high abrasion property and high radiation resistance. High-density polyethylene (HDPE) has a higher gel fraction in irradiation at molten state than irradiation at ordinary temperature. Crosslinked HDPE has been applied as knee joints in order to have high abrasion. Radiation crosslinked polycarbosilane (PCS) fiber gives high heat resistant silicon carbide (SiC) after firing. EB irradiation of PCS is effective to improve strength of product and to inhibit flow during carbonization. SiC, being resistant to high temperature will be applied in turbine and body of rockets. (author)

Actuator device utilizing a conductive polymer gel

Science.gov (United States)

Chinn, Douglas A.; Irvin, David J.

2004-02-03

A valve actuator based on a conductive polymer gel is disclosed. A nonconductive housing is provided having two separate chambers separated by a porous frit. The conductive polymer is held in one chamber and an electrolyte solution, used as a source of charged ions, is held in the second chamber. The ends of the housing a sealed with a flexible elastomer. The polymer gel is further provide with electrodes with which to apply an electrical potential across the gel in order to initiate an oxidation reaction which in turn drives anions across the porous frit and into the polymer gel, swelling the volume of the gel and simultaneously contracting the volume of the electrolyte solution. Because the two end chambers are sealed the flexible elastomer expands or contracts with the chamber volume change. By manipulating the potential across the gel the motion of the elastomer can be controlled to act as a "gate" to open or close a fluid channel and thereby control flow through that channel.

Radiation chemistry of biologically compatible polymers

International Nuclear Information System (INIS)

Hill, D.J. T.; Pomery, P.J.; Saadat, G.; Whittaker, A.K.

1996-01-01

Full text: Poly (2-hydroxy ethyl methacrylate) [PHEMA] and poly (2-ethoxy ethyl methacrylate) [PEEMA] are of biomedical and industrial interest due to their biocompatibility with living tissue. In this paper the effect of high energy radiation on these polymers is reported. PHEMA and PEEMA have similar molecular structures to poly (methyl methacrylate)[PMMA], and the γ irradiation of this polymer is well understood. Hence the radiation chemistry of PMMA is used as model system for the the analysis of the radiation chemistry of these polymers. The mechanism of the radiation induced chemistry of the polymers has been investigated using a range of techniques including electron spin resonance spectroscopy (ESR) to establish free radical pathways, GC to identify small molecule volatile products, NMR to identify small molecule radiation products and Gel Permeation Chromatography (GPC) to determine molecular weight changes. Whilst much of the major part of the radiation chemistry can be attributed to similar reactions which can be observed in PMMA, there are a number of new radicals which are present as a result of the influence of the side chain interactions which reduces the mobility of the polymer chain

Polymer architecture of magnetic gels: a review

Science.gov (United States)

Weeber, Rudolf; Hermes, Melissa; Schmidt, Annette M.; Holm, Christian

2018-02-01

In this review article, we provide an introduction to ferrogels, i.e. polymeric gels with embedded magnetic particles. Due to the interplay between magnetic and elastic properties of these materials, they are promising candidates for engineering and biomedical applications such as actuation and controlled drug release. Particular emphasis will be put on the polymer architecture of magnetic gels since it controls the degrees of freedom of the magnetic particles in the gel, and it is important for the particle-polymer coupling determining the mechanisms available for the gel deformation in magnetic fields. We report on the different polymer architectures that have been realized so far, and provide an overview of synthesis strategies and experimental techniques for the characterization of these materials. We further focus on theoretical and simulational studies carried out on magnetic gels, and highlight their contributions towards understanding the influence of the gels’ polymer architecture.

Radiation Processing of Natural Polymers for Industrial Applications

International Nuclear Information System (INIS)

Hegazy, E.A.

2008-01-01

Radiation induced degradation technology is a new and promising application of ionizing radiation to develop viscose, pulp, paper, food preservation, pharmaceutical production, and natural bioactive agents industries. Controlling the degree of degradation, uniform molecular weight distribution, saving achieved in the chemicals (used in conventional methods) on a cost basis, and environmentally friendly process are the beneficial effects of using radiation technology in these industries. However, for some development countries such technology is not economic. Therefore, a great effort should be done to reduce the cost required for such technologies. One of the principle factors for reducing the cost is achieving the degradation at low irradiation doses. The addition of some additives such as potassium per-sulfate (KPS), ammonium per-sulfate (APS), or H 2 O 2 to natural polymers (carboxy-methylcellulose (CMC), chitosan, carrageenan and Na-alginate) during irradiation process accelerates their degradation. The highest degradation rate of polysaccharides obtained when APS was used. The end product of irradiated CMC, chitosan, carrageenan and Na-alginate may be used as food additive or benefited in agricultural purposes. On the other hand, radiation crosslinking of PAAm or PNIPAAm is affected by the presence of natural polymer like CMC-Na and carrageenan due to their degradability which could be controlled according to its concentration in the bulk medium and irradiation dose. Accordingly, the gel content, thermo-sensitivity (LCST) and swelling properties of PNIPAAm based natural polymers could be controlled. The swelling of the prepared copolymer hydrogels was investigated for its possible use in personal care articles particularly diapers or as carriers for drug delivery systems. The prepared crosslinked copolymers possessed high and fast swelling properties in simulated urine media and the swelling ratios of CMC-Na /PAAm gels in urine are acceptable for diaper

Detection of ultraviolet radiation using tissue equivalent radiochromic gel materials

International Nuclear Information System (INIS)

Bero, M A; Abukassem, I

2009-01-01

Ferrous Xylenol-orange Gelatin gel (FXG) is known to be sensitive to ionising radiation such as γ and X-rays. The effect of ionising radiation is to produce an increase in the absorption over a wide region of the visible spectrum, which is proportional to the absorbed dose. This study demonstrates that FXG gel is sensitive to ultraviolet radiation and therefore it could functions as UV detector. Short exposure to UV radiation produces linear increase in absorption measured at 550nm, however high doses of UV cause the ion indicator colour to fad away in a manner proportional to the incident UV energy. Light absorbance increase at the rate of 1.1% per minute of irradiation was monitored. The exposure level at which the detector has linear response is comparable to the natural summer UV radiation. Evaluating the UV ability to pass through tissue equivalent gel materials shows that most of the UV gets absorbed in the first 5mm of the gel materials, which demonstrate the damaging effects of this radiation type on human skin and eyes. It was concluded that FXG gel dosimeter has the potential to offer a simple, passive ultraviolet radiation detector with sensitivity suitable to measure and visualises the natural sunlight UV exposure directly by watching the materials colour changes.

Detection of ultraviolet radiation using tissue equivalent radiochromic gel materials

Science.gov (United States)

Bero, M. A.; Abukassem, I.

2009-05-01

Ferrous Xylenol-orange Gelatin gel (FXG) is known to be sensitive to ionising radiation such as γ and X-rays. The effect of ionising radiation is to produce an increase in the absorption over a wide region of the visible spectrum, which is proportional to the absorbed dose. This study demonstrates that FXG gel is sensitive to ultraviolet radiation and therefore it could functions as UV detector. Short exposure to UV radiation produces linear increase in absorption measured at 550nm, however high doses of UV cause the ion indicator colour to fad away in a manner proportional to the incident UV energy. Light absorbance increase at the rate of 1.1% per minute of irradiation was monitored. The exposure level at which the detector has linear response is comparable to the natural summer UV radiation. Evaluating the UV ability to pass through tissue equivalent gel materials shows that most of the UV gets absorbed in the first 5mm of the gel materials, which demonstrate the damaging effects of this radiation type on human skin and eyes. It was concluded that FXG gel dosimeter has the potential to offer a simple, passive ultraviolet radiation detector with sensitivity suitable to measure and visualises the natural sunlight UV exposure directly by watching the materials colour changes.

Polymer and Polymer Gel of Liquid Crystalline Semiconductors

Institute of Scientific and Technical Information of China (English)

Teppei Shimakawa; Naoki Yoshimoto; Jun-ichi Hanna

2004-01-01

It prepared a polymer and polymer gel of a liquid crystalline (LC) semiconductor having a 2-phenylnaphthalene moiety and studied their charge carrier transport properties by the time-of-flight technique. It is found that polyacrylate having the mesogenic core moiety of 2-phenylnaphtalene (PNP-acrylate) exhibited a comparable mobility of 10-4cm2/Vs in smectic A phase to those in smectic A (SmA) phase of small molecular liquid crystals with the same core moiety, e.g., 6-(4'-octylphenyl)- 2-dodecyloxynaphthalene (8-PNP-O12), and an enhanced mobility up to 10-3cm2/Vs in the LC-glassy phase at room temperature, when mixed with a small amount of 8-PNP-O12. On the other hand, the polymer gel consisting of 20 wt %-hexamethylenediacrylate (HDA)-based cross-linked polymer and 8-PNP-O12 exhibited no degraded mobility when cross-linked at the mesophase. These results indicate that the polymer and polymer composite of liquid crystalline semiconductors provide us with an easy way to realize a quality organic semiconductor thin film for the immediate device applications.

Investigating potential physicochemical errors in polymer gel dosimeters

International Nuclear Information System (INIS)

Sedaghat, Mahbod; Lepage, Martin; Bujold, Rachel

2011-01-01

Measurement errors in polymer gel dosimetry can originate either during irradiation or scanning. One concern related to the exothermic nature of polymerization reaction was that the heat released in polymer gel dosimeters during irradiation modifies their dose response. In this paper, the effect of heat released from the exothermal polymerization reaction on the dose response of a number of dosimeters was studied. In addition, we investigated whether heat-generated geometric distortion existed in newly proposed gel dosimeters that contain highly thermoresponsive polymers. Our results suggest that despite a significant internal temperature increase in some gel compositions, their dose responses are not affected when oxygen is well expelled mechanically from the gel mixture. We also report on significant pre-irradiation instability in some recently developed polymer gel dosimeters but that geometric distortions were not observed. Data obtained by a set of small calibration vials are compared to those obtained from larger phantoms, and potential physicochemical causes of deviations between them are identified.

Investigating potential physicochemical errors in polymer gel dosimeters

Energy Technology Data Exchange (ETDEWEB)

Sedaghat, Mahbod; Lepage, Martin [Centre d' imagerie moleculaire de Sherbrooke, Departement de medecine nucleaire et radiobiologie, Universite de Sherbrooke, Sherbrooke, QC (Canada); Bujold, Rachel, E-mail: martin.lepage@usherbrooke.ca [Service de radio-oncologie, Centre hospitalier universitaire de Sherbrooke, Sherbrooke, QC (Canada)

2011-09-21

Measurement errors in polymer gel dosimetry can originate either during irradiation or scanning. One concern related to the exothermic nature of polymerization reaction was that the heat released in polymer gel dosimeters during irradiation modifies their dose response. In this paper, the effect of heat released from the exothermal polymerization reaction on the dose response of a number of dosimeters was studied. In addition, we investigated whether heat-generated geometric distortion existed in newly proposed gel dosimeters that contain highly thermoresponsive polymers. Our results suggest that despite a significant internal temperature increase in some gel compositions, their dose responses are not affected when oxygen is well expelled mechanically from the gel mixture. We also report on significant pre-irradiation instability in some recently developed polymer gel dosimeters but that geometric distortions were not observed. Data obtained by a set of small calibration vials are compared to those obtained from larger phantoms, and potential physicochemical causes of deviations between them are identified.

Investigation of optimal scanning protocol for X-ray computed tomography polymer gel dosimetry

Energy Technology Data Exchange (ETDEWEB)

Sellakumar, P. [Bangalore Institute of Oncology, 44-45/2, II Cross, RRMR Extension, Bangalore 560 027 (India)], E-mail: psellakumar@rediffmail.com; James Jebaseelan Samuel, E. [School of Science and Humanities, VIT University, Vellore 632 014 (India); Supe, Sanjay S. [Department of Radiation Physics, Kidwai Memorial Institute of Oncology, Hosur Road, Bangalore 560 027 (India)

2007-11-15

X-ray computed tomography is one of the potential tool used to evaluate the polymer gel dosimeters in three dimensions. The purpose of this study is to investigate the factors which affect the image noise for X-ray CT polymer gel dosimetry. A cylindrical water filled phantom was imaged with single slice Siemens Somatom Emotion CT scanner. The imaging parameters like tube voltage, tube current, slice scan time, slice thickness and reconstruction algorithm were varied independently to study the dependence of noise on each other. Reductions of noise with number of images to be averaged and spatial uniformity of the image were also investigated. Normoxic polymer gel PAGAT was manufactured and irradiated using Siemens Primus linear accelerator. The radiation induced change in CT number was evaluated using X-ray CT scanner. From this study it is clear that image noise is reduced with increase in tube voltage, tube current, slice scan time, slice thickness and also reduced with increasing the number of images averaged. However to reduce the tube load and total scan time, it was concluded that tube voltage of 130 kV, tube current of 200 mA, scan time of 1.5 s, slice thickness of 3 mm for high dose gradient and 5 mm for low dose gradient were optimal scanning protocols for this scanner. Optimum number of images to be averaged was concluded to be 25 for X-ray CT polymer gel dosimetry. Choice of reconstruction algorithm was also critical. From the study it is also clear that CT number increase with imaging tube voltage and shows the energy dependency of polymer gel dosimeter. Hence for evaluation of polymer gel dosimeters with X-ray CT scanner needs the optimization of scanning protocols to reduce the image noise.

Determine the Dose Distribution Using Ultrasound Parameters in MAGIC-f Polymer Gels

Directory of Open Access Journals (Sweden)

Hossein Masoumi

2016-02-01

Full Text Available In this study, using methacrylic and ascorbic acid in gelatin initiated by copper (MAGIC-f polymer gel after megavoltage energy exposure, the sensitivity of the ultrasound velocity and attenuation coefficient dose-dependent parameters was evaluated. The MAGIC-f polymer gel was irradiated under 1.25 MeV cobalt-60, ranging from 0 to 60 Gy in 2-Gy steps, and received dose uniformity and accuracy of ±2%. After calibration of the ultrasonic systems with a frequency of 500 kHz, the parameters of ultrasound velocity and attenuation coefficient of the irradiated gel samples were measured. According to the dose–response curve, the ability of ultrasonic parameters was evaluated in dose rate readings. Based on a 4-order polynomial curve, fitted on the dose–response parameters of ultrasound velocity and attenuation coefficient and observed at 24 hours after irradiation, ultrasonic parameters had more sensitivity. The sensitivity of the dose–velocity and dose-attenuation coefficient curves was observed as 50 m/s/Gy and 0.06 dB/MHz/Gy over the linear range of 4 to 44 Gy, respectively. The ultrasonic parameters at 5°C, 15°C, and 25°C on the gel dosimeter after 0 to 60 Gy irradiation showed that readings at 25°C have higher sensitivity compared to 15°C and 5°C. Maximum sensitivity time and temperature readings of the MAGIC-f ultrasonic parameters were concluded 24 hours after irradiation and at a temperature of 25°C.

Radiation processing of natural polymers for industrial and agricultural applications

International Nuclear Information System (INIS)

Hegazy, El-Sayed A.; AbdEl-Rehim, H.; Diaa, D.A.; El-Barbary, A.

2008-01-01

Radiation induced degradation technology is a new and promising application of ionizing radiation to develop viscose, pulp, paper, food preservation, pharmaceutical production, and natural bioactive agents industries. Controlling the degree of degradation, uniform molecular weight distribution, saving achieved in the chemicals (used in conventional methods) on a cost basis, and environmentally friendly process are the beneficial effects of using radiation technology in these industries. However, for some development countries such technology is not economic. Therefore, a great efforts should be done to reduce the cost required for such technologies. One of the principle factors for reducing the cost is achieving the degradation at low irradiation doses. The addition of some additives such as potassium per-sulfate (KPS), ammonium per-sulfate (APS), or H 2 O 2 to natural polymers (carboxymethylcellulose (CMC), chitosan, carrageenan and Na-alginate) during irradiation process accelerates their degradation. The highest degradation rate of polysaccharides obtained when APS was used. The end product of irradiated CMC, chitosan, carrageenan and Na-alginate may be used as food additive or benefited in agricultural purposes. On the other hand, radiation crosslinking of PAAm or PNIPAAm is affected by the presence of natural polymer like CMC-Na and carrageenan due to their degradability which could be controlled according to its concentration in the bulk medium and irradiation dose. Accordingly, the gel content, thermo-sensitivity (LCST) and swelling properties of PNIPAAm based natural polymers could be controlled. The swelling of the prepared copolymer hydrogels was investigated for its possible use in personal care articles particularly diapers or as carriers for drug delivery systems. The prepared crosslinked copolymers possessed high and fast swelling properties in simulated urine media and the swelling ratios of CMC-Na/PAAm gels in urine are acceptable for diaper

Water equivalence of NIPAM based polymer gel dosimeters with enhanced sensitivity for x-ray CT

International Nuclear Information System (INIS)

Gorjiara, Tina; Hill, Robin; Bosi, Stephen; Kuncic, Zdenka; Baldock, Clive

2013-01-01

Two new formulations of N-isopropylacrylamide (NIPAM) based three dimensional (3D) gel dosimeters have recently been developed with improved sensitivity to x-ray CT readout, one without any co-solvent and the other one with isopropanol co-solvent. The water equivalence of the NIPAM gel dosimeters was investigated using different methods to calculate their radiological properties including: density, electron density, number of electrons per grams, effective atomic number, photon interaction probabilities, mass attenuation and energy absorption coefficients, electron collisional, radiative and total mass stopping powers and electron mass scattering power. Monte Carlo modelling was also used to compare the dose response of these gel dosimeters with water for kilovoltage and megavoltage x-ray beams and for megavoltage electron beams. We found that the density and electron density of the co-solvent free gel dosimeter are more water equivalent with less than a 2.6% difference compared to a 5.7% difference for the isopropanol gel dosimeter. Both the co-solvent free and isopropanol solvent gel dosimeters have lower effective atomic numbers than water, differing by 2.2% and 6.5%, respectively. As a result, their photoelectric absorption interaction probabilities are up to 6% and 19% different from water, respectively. Compton scattering and pair production interaction probabilities of NIPAM gel with isopropanol differ by up to 10% from water while for the co-solvent free gel, the differences are 3%. Mass attenuation and energy absorption coefficients of the co-solvent free gel dosimeter and the isopropanol gel dosimeter are up to 7% and 19% lower than water, respectively. Collisional and total mass stopping powers of both gel dosimeters differ by less than 2% from those of water. The dose response of the co-solvent free gel dosimeter is water equivalent (with 100 keV, correction factor is required for the gels. • For MV electron, correction factor needed for the gels to

Fundamentals of Polymer Gel Dosimeters

Science.gov (United States)

McAuley, Kim B.

2006-12-01

The recent literature on polymer gel dosimetry contains application papers and basic experimental studies involving polymethacrylic-acid-based and polyacrylamide-based gel dosimeters. The basic studies assess the relative merits of these two most commonly used dosimeters, and explore the effects of tetrakis hydroxymethyl phosphonium chloride (THPC) antioxidant on dosimeter performance. Polymer gel dosimeters that contain THPC or other oxygen scavengers are called normoxic dosimeters, because they can be prepared under normal atmospheric conditions, rather than in a glove box that excludes oxygen. In this review, an effort is made to explain some of the underlying chemical phenomena that affect dosimeter performance using THPC, and that lead to differences in behaviour between dosimeters made using the two types of monomer systems. Progress on the development of new more effective and less toxic dosimeters is also reported.

Comparison of non-electrophoresis grade with electrophoresis grade BIS in NIPAM polymer gel preparation

Science.gov (United States)

Khodadadi, Roghayeh; Khajeali, Azim; Farajollahi, Ali Reza; Hajalioghli, Parisa; Raeisi, Noorallah

2015-01-01

Introduction:The main objective of this study was to investigate the possibility of replacing electrophoresis cross-linker with non-electrophoresis N, N′-methylenebisacrylamide (BIS) in N-isopropyl acrylamide (NIPAM) polymer gel and its possible effect on dose response. Methods: NIPAM polymer gel was prepared from non-electrophoresis grade BIS and the relaxation rate (R2) was measured by MR imaging after exposing the gel to gamma radiation from Co-60 source. To compare the response of this gel with the one that contains electrophoresis grade BIS, two sets of NIPAM gel were prepared using electrophoresis and non-electrophoresis BIS and irradiated to different gamma doses. Results: It was found that the dose–response of NIPAM gel made from the non-electrophoresis grade BIS is coincident with that of electrophoresis grade BIS. Conclusion:Taken all, it can be concluded that the non-electrophoresis grade BIS not only is a suitable alternative for the electrophoresis grade BIS but also reduces the cost of gel due to its lower price. PMID:26457250

Efficient and Stable Photovoltaic Characteristics of Quasi-Solid State DSSC using Polymer Gel Electrolyte Based on Ionic Liquid in Organosiloxane Polymer Gels

Science.gov (United States)

Pujiarti, H.; Arsyad, W. S.; Shobih; Muliani, L.; Hidayat, R.

2018-04-01

Dye-Sensitized Solar Cell (DSSC) is still one of the promising solar cell types among the third generation of solar cells because of easiness of fabrication and variety of available materials. In this type of solar cell, the electrolyte is one of the important components for regenerating excited dyes and transporting electric charge carriers to the counter electrode. Indeed, the power conversion efficiency of DSSC can be then significantly affected by the chemical and physical properties of the electrolyte. The simplest electrolyte system of an I-/I3 - redox couple in an organic solvent, however, has some drawbacks due to corrosive properties, volatile and leakage problem. Use of solid phase or gel phase electrolyte may overcome those problems, but it is often considered to suppress the efficiency due to low ion diffusion. Here, we report the photovoltaic characteristics of DSSC using polymer gel electrolyte (PGE), which is composed of ionic liquid and an organosiloxane polymer gel. The better cell performance with power conversion efficiency of about 6% has been obtained by optimizing the mesoporous size of the TiO2 layer and the PGE viscosity.

Water equivalence of NIPAM based polymer gel dosimeters with enhanced sensitivity for x-ray CT

Science.gov (United States)

Gorjiara, Tina; Hill, Robin; Bosi, Stephen; Kuncic, Zdenka; Baldock, Clive

2013-10-01

Two new formulations of N-isopropylacrylamide (NIPAM) based three dimensional (3D) gel dosimeters have recently been developed with improved sensitivity to x-ray CT readout, one without any co-solvent and the other one with isopropanol co-solvent. The water equivalence of the NIPAM gel dosimeters was investigated using different methods to calculate their radiological properties including: density, electron density, number of electrons per grams, effective atomic number, photon interaction probabilities, mass attenuation and energy absorption coefficients, electron collisional, radiative and total mass stopping powers and electron mass scattering power. Monte Carlo modelling was also used to compare the dose response of these gel dosimeters with water for kilovoltage and megavoltage x-ray beams and for megavoltage electron beams. We found that the density and electron density of the co-solvent free gel dosimeter are more water equivalent with less than a 2.6% difference compared to a 5.7% difference for the isopropanol gel dosimeter. Both the co-solvent free and isopropanol solvent gel dosimeters have lower effective atomic numbers than water, differing by 2.2% and 6.5%, respectively. As a result, their photoelectric absorption interaction probabilities are up to 6% and 19% different from water, respectively. Compton scattering and pair production interaction probabilities of NIPAM gel with isopropanol differ by up to 10% from water while for the co-solvent free gel, the differences are 3%. Mass attenuation and energy absorption coefficients of the co-solvent free gel dosimeter and the isopropanol gel dosimeter are up to 7% and 19% lower than water, respectively. Collisional and total mass stopping powers of both gel dosimeters differ by less than 2% from those of water. The dose response of the co-solvent free gel dosimeter is water equivalent (with x-ray beams over the energy range 180 keV-18 MV, both gel dosimeters have less than 2% discrepancy with water. For

Polymeric reaction of polymer-monomer system for pressure sensitive adhesives by low energy electron beam

International Nuclear Information System (INIS)

Takiguchi, R.; Uryu, T.

1985-01-01

Application of low-energy electron beam to non-solvent type pressure sensitive adhesives is investigated. The adhesive properties such as peel strength and holding time (dead-load strength) were closely related to the reaction of acrylate polymer-monomer systems. The reaction behavior is elucidated by combining the measurement of gel fraction, infrared spectrum of gel, and the molecular weight distribution detected by gel permeation chromatography. It was important for the production of pressure sensitive adhesives by electron beam that the adhesive with high peel strength and long holding time is composed of a proper combination of three factors, that is, about 35% gel fraction, 25% monomer units in gel, and 15% graft efficiency by irradiating the polymer-monomer system containing low molecular weight poly (butyl acrylate). (author)

A novel method of estimating dose responses for polymer gels using texture analysis of scanning electron microscopy images.

Directory of Open Access Journals (Sweden)

Cheng-Ting Shih

Full Text Available Polymer gels are regarded as a potential dosimeter for independent validation of absorbed doses in clinical radiotherapy. Several imaging modalities have been used to convert radiation-induced polymerization to absorbed doses from a macro-scale viewpoint. This study developed a novel dose conversion mechanism by texture analysis of scanning electron microscopy (SEM images. The modified N-isopropyl-acrylamide (NIPAM gels were prepared under normoxic conditions, and were administered radiation doses from 5 to 20 Gy. After freeze drying, the gel samples were sliced for SEM scanning with 50×, 500×, and 3500× magnifications. Four texture indices were calculated based on the gray level co-occurrence matrix (GLCM. The results showed that entropy and homogeneity were more suitable than contrast and energy as dose indices for higher linearity and sensitivity of the dose response curves. After parameter optimization, an R (2 value of 0.993 can be achieved for homogeneity using 500× magnified SEM images with 27 pixel offsets and no outlier exclusion. For dose verification, the percentage errors between the prescribed dose and the measured dose for 5, 10, 15, and 20 Gy were -7.60%, 5.80%, 2.53%, and -0.95%, respectively. We conclude that texture analysis can be applied to the SEM images of gel dosimeters to accurately convert micro-scale structural features to absorbed doses. The proposed method may extend the feasibility of applying gel dosimeters in the fields of diagnostic radiology and radiation protection.

Correlation between ionic conductivity and fluidity of polymer gel ...

Indian Academy of Sciences (India)

Unknown

Ionic conductivity; ion aggregates; FTIR spectroscopy; gels; fluidity. 1. Introduction ... liquid and polymer gel electrolytes have been studied as functions of salt ..... Ratner M A 1987 in Polymer electrolyte reviews (eds) J R. MacCallum and C A ...

Use of normoxic polymer gel dosimeters for measuring diagnostic doses on CT scanners

International Nuclear Information System (INIS)

Hill, B; Venning, A J; Baldock, C

2004-01-01

X-ray CT has been used to evaluate polymer gel dosimeters for dose response in the therapeutic dose range. This method of polymer gel dosimeter evaluation has been shown to be useful for instance in the comparison of complex sterotactic field distributions with treatment plans. Image averaging and subtraction techniques are used for noise reduction in polymer gel dosimeters resulting in the delivery of several CT slices across the polymer gel dosimeters. It was a logical progression to evaluate normoxic polymer gel dosimeters with optimized CT scanning protocols. During these investigations it was found that unirradiated regions in irradiated normoxic polymer gel dosimetry phantoms polymerised possibly as a result of the evaluation using CT. This prompted an investigation of the CT diagnostic dose response of the normoxic polymer gel dosimeter in order to determine the dose contribution when evaluated using a CT scanner. Having established that there was an effect on the normoxic polymer gel dosimeter when evaluating with a CT scanner the suitability of these gels in the determination of CT diagnostic dose measurement was further investigated

Contaminant containment using polymer gel barriers

NARCIS (Netherlands)

Darwish, M.I.M.; Rowe, R.K.; Maarel, van der J.R.C.; Pel, L.; Huinink, H.P.; Zitha, P.L.J.

2004-01-01

Polymer gels are well known in the oil industry, but their potential for use as barriers to contaminant transport has not previously received significant study. As a first step, this paper examines the potential for a polyelectrolyte gel to serve as a barrier to the migration of sodium chloride. Two

Modelling of the inhomogeneous interior of polymer gels

International Nuclear Information System (INIS)

Shew, C-Y; Iwaki, Takafumi

2006-01-01

A simple model has been investigated to elucidate the mean squared displacement (MSD) of probe molecules in cross-linked polymer gels. In the model, we assume that numerous cavities distribute in the inhomogeneous interior of a gel, and probe molecules are confined within these cavities. The individual probe molecules trapped in a gel are treated as Brownian particles confined to a spherical harmonic potential. The harmonic potential is chosen to model the effective potential experienced by the probe particle in the cavity of a gel. Each field strength is corresponding to the characteristic of one type of effective cavity. Since the statistical distribution of different effective cavity sizes is unknown, several distribution functions are examined. Meanwhile, the calculated averaged MSDs are compared to the experimental data by Nisato et al (2000 Phys. Rev. E 61 2879). We find that the theoretical results of the MSD are sensitive to the shape of the distribution function. For low cross-linked gels, the best fit is obtained when the interior cavities of a gel follow a bimodal distribution. Such a result may be attributed to the presence of at least two distinct classes of cavity in gels. For high cross-linked gels, the cavities in the gel can be depicted by a single-modal uniform distribution function, suggesting that the range of cavity sizes becomes smaller. These results manifest the voids inside a gel, and the shape of distribution functions may provide the insight into the inhomogeneous interior of a gel

Molecular structure effects on the post irradiation diffusion in polymer gel dosimeters

Energy Technology Data Exchange (ETDEWEB)

Mattea, F.; Romero, M.; Strumia, M. [Instituto Multidisciplinario de Biologia Vegetal / CONICET, Universidad Nacional de Cordoba, Departamento de Quimica Organica, Ciudad Universitaria, 5000 Cordoba (Argentina); Vedelago, J. [Laboratorio de Investigaciones e Instrumentacion en Fisica Aplicada a la Medicina e Imagenes por Rayos X, Laboratorio 448 FaMAF - UNC, Ciudad Universitaria, 5000 Cordoba (Argentina); Quiroga, A. [Centro de Investigacion y Estudios de Matematica / CONICET, Oficina 318 FaMAF - UNC, Ciudad Universitaria, 5000 Cordoba (Argentina); Valente, M., E-mail: fmattea@gmail.com [Instituto de Fisica E. Gaviola / CONICET, LIIFAMIRx, Oficina 102 FaMAF - UNC, 5000 Cordoba (Argentina)

2014-08-15

Polymer gel dosimeters have specific advantages for recording 3D radiation dose distribution representing a key factor for most of the therapeutic and diagnostic radiation techniques. Radiation-induced polymerization and crosslinking reactions that take place in the dosimeter have been studied for different monomers like acrylamide and N,N-methylene-bis acrylamide (Bis) and most recently for less toxic monomers like N-isopropylacrylamide and Bis. In this work a novel system based on itaconic acid and Bis is proposed, the radical polymerization or gel formation of these monomers has been already studied for the formation of an hydrogel for non dosimetric applications and their reactivity are comparable with the already mentioned systems. Although the 3D structure is maintained after the dosimeter has been irradiated, it is not possible to eliminate the diffusion of the reacted and monomer species in regions of dose gradients within the gel after irradiation. As a consequence the dose information of the dosimeters loose quality over time. The mobility within the gelatin structure of the already mentioned species is related to their chemical structure, and nature. In this work the effect of changes in the chemical structure of the monomers over the dosimetric sensitivity and over the post-irradiation diffusion of species is studied. One of the acrylic acid groups of the itaconic acid molecule is modified to obtain molecules with similar reactivity but different molecular sizes. Dosimetric systems with these modified species, Bis, an antioxidant to avoid oxygen polymerization inhibition, water and gelatin are irradiated in an X-ray tomography at different doses, and the resulting dosimeters are characterized by Raman spectroscopy and optical absorbance to study their feasibility and capabilities as dosimetric systems, and by optical-CT to analyze the diffusion degree after being irradiated. (Author)

Molecular structure effects on the post irradiation diffusion in polymer gel dosimeters

International Nuclear Information System (INIS)

Mattea, F.; Romero, M.; Strumia, M.; Vedelago, J.; Quiroga, A.; Valente, M.

2014-08-01

Polymer gel dosimeters have specific advantages for recording 3D radiation dose distribution representing a key factor for most of the therapeutic and diagnostic radiation techniques. Radiation-induced polymerization and crosslinking reactions that take place in the dosimeter have been studied for different monomers like acrylamide and N,N-methylene-bis acrylamide (Bis) and most recently for less toxic monomers like N-isopropylacrylamide and Bis. In this work a novel system based on itaconic acid and Bis is proposed, the radical polymerization or gel formation of these monomers has been already studied for the formation of an hydrogel for non dosimetric applications and their reactivity are comparable with the already mentioned systems. Although the 3D structure is maintained after the dosimeter has been irradiated, it is not possible to eliminate the diffusion of the reacted and monomer species in regions of dose gradients within the gel after irradiation. As a consequence the dose information of the dosimeters loose quality over time. The mobility within the gelatin structure of the already mentioned species is related to their chemical structure, and nature. In this work the effect of changes in the chemical structure of the monomers over the dosimetric sensitivity and over the post-irradiation diffusion of species is studied. One of the acrylic acid groups of the itaconic acid molecule is modified to obtain molecules with similar reactivity but different molecular sizes. Dosimetric systems with these modified species, Bis, an antioxidant to avoid oxygen polymerization inhibition, water and gelatin are irradiated in an X-ray tomography at different doses, and the resulting dosimeters are characterized by Raman spectroscopy and optical absorbance to study their feasibility and capabilities as dosimetric systems, and by optical-CT to analyze the diffusion degree after being irradiated. (Author)

pH and temperature dual-sensitive liposome gel based on novel cleavable mPEG-Hz-CHEMS polymeric vaginal delivery system

Directory of Open Access Journals (Sweden)

Chen D

2012-05-01

Full Text Available Daquan Chen,1,2 Kaoxiang Sun,1,2 Hongjie Mu,1 Mingtan Tang,3 Rongcai Liang,1,2 Aiping Wang,1,2 Shasha Zhou,1 Haijun Sun,1 Feng Zhao,1 Jianwen Yao,1 Wanhui Liu1,21School of Pharmacy, Yantai University, 2State Key Laboratory of Longacting and Targeting Drug Delivery Systems, Yantai, 3School of Pharmaceutical Sciences, Shandong University, Jinan, People's Republic of ChinaBackground: In this study, a pH and temperature dual-sensitive liposome gel based on a novel cleavable hydrazone-based pH-sensitive methoxy polyethylene glycol 2000-hydrazone-cholesteryl hemisuccinate (mPEG-Hz-CHEMS polymer was used for vaginal administration.Methods: The pH-sensitive, cleavable mPEG-Hz-CHEMS was designed as a modified pH-sensitive liposome that would selectively degrade under locally acidic vaginal conditions. The novel pH-sensitive liposome was engineered to form a thermogel at body temperature and to degrade in an acidic environment.Results: A dual-sensitive liposome gel with a high encapsulation efficiency of arctigenin was formed and improved the solubility of arctigenin characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry. The dual-sensitive liposome gel with a sol-gel transition at body temperature was degraded in a pH-dependent manner, and was stable for a long period of time at neutral and basic pH, but cleavable under acidic conditions (pH 5.0. Arctigenin encapsulated in a dual-sensitive liposome gel was more stable and less toxic than arctigenin loaded into pH-sensitive liposomes. In vitro drug release results indicated that dual-sensitive liposome gels showed constant release of arctigenin over 3 days, but showed sustained release of arctigenin in buffers at pH 7.4 and pH 9.0.Conclusion: This research has shed some light on a pH and temperature dual-sensitive liposome gel using a cleavable mPEG-Hz-CHEMS polymer for vaginal delivery.Keywords: mPEG-Hz-CHEMS polymer, pH-sensitive liposomes, thermosensitive

Feasibility of quantitative PET/CT dosimetry for proton therapy using polymer gels

Energy Technology Data Exchange (ETDEWEB)

Zeidan, O A; Hsi, W C; Lopatiuk-Tirpak, O; Sriprisan, S I; Meeks, S L; Kupelian, P A; Li, Z; Palta, J R, E-mail: lenatirpak@gmail.co

2010-11-01

A feasibility study of proton beam PET/CT off-line quantitative dosimetry using polymer gels is presented. A newly developed proton-sensitive polymer gel dosimeter (BANG( (registered)) 3-Pro2) is used as a dosimeter and a tissue-equivalent phantom medium for this study. We explore a new approach to correlating measured proton 3-dimensional (3D) dose distributions directly to measured positron emission from in the gel medium using PET/CT imaging. A large cylindrical volume (2.2 Litres) of the gel was irradiated with a clinical modulated proton beam using irregular-shaped aperture geometry. The gel was imaged in a nearby PET/CT unit immediately (<3 min) after irradiation. Dose distribution in the gel was generated using an optical tomography scanning system. Direct 3D spatial comparison of dose and positron emission distributions was then performed. Profiles along the beam path show that the distal fall-off of the dose is nearly 2 cm deeper than the activity profile which is comparable to previous studies with plastic phantoms and Monte Carlo simulations of activity distributions. Planar PET and dose distributions at depth and perpendicular to beam axis show a strong one-to-one spatial correlation. This phantom study demonstrates that the gel medium could be potentially useful for quantifying various physical factors that can influence the PET activity range verification method in patients.

SU-E-T-753: Three-Dimensional Dose Distributions of Incident Proton Particle in the Polymer Gel Dosimeter and the Radiochromic Gel Dosimeter: A Simulation Study with MCNP Code

International Nuclear Information System (INIS)

Park, M; Kim, G; Ji, Y; Kim, K; Park, S; Jung, H

2015-01-01

Purpose: The purpose of this study is to estimate the three-dimensional dose distributions in the polymer and the radiochromic gel dosimeter, and to identify the detectability of both gel dosimeters by comparing with the water phantom in case of irradiating the proton particles. Methods: The normoxic polymer gel and the LCV micelle radiochromic gel were used in this study. The densities of polymer and the radiochromic gel dosimeter were 1.024 and 1.005 g/cm 3 , respectively. The dose distributions of protons in the polymer and radiochromic gel were simulated using Monte Carlo radiation transport code (MCNPX, Los Alamos National Laboratory). The shape of phantom irradiated by proton particles was a hexahedron with the dimension of 12.4 × 12.4 × 15.0 cm 3 . The energies of proton beam were 50, 80, and 140 MeV energies were directed to top of the surface of phantom. The cross-sectional view of proton dose distribution in both gel dosimeters was estimated with the water phantom and evaluated by the gamma evaluation method. In addition, the absorbed dose(Gy) was also calculated for evaluating the proton detectability. Results: The evaluation results show that dose distributions in both gel dosimeters at intermediated section and Bragg-peak region are similar with that of the water phantom. At entrance section, however, inconsistencies of dose distribution are represented, compared with water. The relative absorbed doses in radiochromic and polymer gel dosimeter were represented to be 0.47 % and 2.26 % difference, respectively. These results show that the radiochromic gel dosimeter was better matched than the water phantom in the absorbed dose evaluation. Conclusion: The polymer and the radiochromic gel dosimeter show similar characteristics in dose distributions for the proton beams at intermediate section and Bragg-peak region. Moreover the calculated absorbed dose in both gel dosimeters represents similar tendency by comparing with that in water phantom

Improvement of ionic conductivity and performance of quasi-solid-state dye sensitized solar cell using PEO/PMMA gel electrolyte

International Nuclear Information System (INIS)

Aram, E.; Ehsani, M.; Khonakdar, H.A.

2015-01-01

Graphical abstract: Reduced interfacial resistance of a quasi-solid-state dye sensitized solar cell with PEO/PMMA blend gel electrolytes. - Highlights: • A new polymer gel electrolyte containing PEO/PMMA was developed for DSSCs. • Optimization of polymer gel electrolyte was done for dye sensitized solar cell. • The best ionic conductivity was found in PEO/PMMA blend with 10/90 w/w composition. • The DSSC with the PEO/PMMA based electrolyte showed good photovoltaic performance. • Significant stability improvement for quasi-solid state DSSC was obtained. - Abstract: Polymer blend gel electrolytes based on polyethylene oxide (PEO) and poly(methyl methacrylate) (PMMA) as host polymers with various weight ratios, LiI/I 2 as redox couple in electrolyte and 4-tert-butyl pyridine as additive were prepared by solution method. The introduction of PMMA in the PEO gel electrolyte reduced the degree of crystallinity of PEO, which was confirmed by differential scanning calorimetry (DSC). Complexation and ionic conductivity as a function of temperature were investigated with Fourier transform infrared and ionic conductometry, respectively. A good correlation was found between the degree of crystallinity and ionic conductivity. The reduction in crystallinity, governed by blending ratio, led to improvement of ionic conductivity. The best ionic conductivity was attained in PEO/PMMA blend with 10/90 w/w composition. The performance of a quasi-solid-state dye sensitized solar cell using the optimized polymer gel electrolyte was investigated. The optimized system of high ionic conductivity of 7 mS cm −1 , with fill factor of 0.59, short-circuit density of 11.11 mA cm −2 , open-circuit voltage of 0.75 V and the conversion efficiency of 4.9% under air mass 1.5 irradiation (100 mW cm −2 ) was obtained. The long-term stability of the dye-sensitized solar cell (DSSC) during 600 h was improved by using PEO/PMMA gel electrolyte relative to a liquid type electrolyte

Improvement of ionic conductivity and performance of quasi-solid-state dye sensitized solar cell using PEO/PMMA gel electrolyte

Energy Technology Data Exchange (ETDEWEB)

Aram, E. [Iran Polymer and Petrochemical Institute, 14965/115 Tehran (Iran, Islamic Republic of); Ehsani, M., E-mail: m.ehsani@ippi.ac.ir [Iran Polymer and Petrochemical Institute, 14965/115 Tehran (Iran, Islamic Republic of); Khonakdar, H.A. [Iran Polymer and Petrochemical Institute, 14965/115 Tehran (Iran, Islamic Republic of); Leibniz Institute of Polymer Research, D-01067 Dresden (Germany)

2015-09-10

Graphical abstract: Reduced interfacial resistance of a quasi-solid-state dye sensitized solar cell with PEO/PMMA blend gel electrolytes. - Highlights: • A new polymer gel electrolyte containing PEO/PMMA was developed for DSSCs. • Optimization of polymer gel electrolyte was done for dye sensitized solar cell. • The best ionic conductivity was found in PEO/PMMA blend with 10/90 w/w composition. • The DSSC with the PEO/PMMA based electrolyte showed good photovoltaic performance. • Significant stability improvement for quasi-solid state DSSC was obtained. - Abstract: Polymer blend gel electrolytes based on polyethylene oxide (PEO) and poly(methyl methacrylate) (PMMA) as host polymers with various weight ratios, LiI/I{sub 2} as redox couple in electrolyte and 4-tert-butyl pyridine as additive were prepared by solution method. The introduction of PMMA in the PEO gel electrolyte reduced the degree of crystallinity of PEO, which was confirmed by differential scanning calorimetry (DSC). Complexation and ionic conductivity as a function of temperature were investigated with Fourier transform infrared and ionic conductometry, respectively. A good correlation was found between the degree of crystallinity and ionic conductivity. The reduction in crystallinity, governed by blending ratio, led to improvement of ionic conductivity. The best ionic conductivity was attained in PEO/PMMA blend with 10/90 w/w composition. The performance of a quasi-solid-state dye sensitized solar cell using the optimized polymer gel electrolyte was investigated. The optimized system of high ionic conductivity of 7 mS cm{sup −1}, with fill factor of 0.59, short-circuit density of 11.11 mA cm{sup −2}, open-circuit voltage of 0.75 V and the conversion efficiency of 4.9% under air mass 1.5 irradiation (100 mW cm{sup −2}) was obtained. The long-term stability of the dye-sensitized solar cell (DSSC) during 600 h was improved by using PEO/PMMA gel electrolyte relative to a liquid type

Effect of the exothermal polymerization reaction on polymer gel dosimetric measurements

International Nuclear Information System (INIS)

Sedaghat, Mahbod; Bujold, Rachel; Lepage, Martin

2010-01-01

Discrepancies in polymer gel dosimetric measurements have been observed between containers of different sizes receiving the same radiation dose. We hypothesized that these deviations are caused by a change in the rate of polymerization due to internal heat increase in the gel containers resulting from the exothermic polymerization of monomers. Here, we test this hypothesis in a polyacrylamide gel dosimeter by recording the temperature in glass phantoms of different sizes during and after irradiation. The dose response of the samples was determined with magnetic resonance imaging. The difference of R 2 values along the depth of the containers was below ±1%. We discuss that this small difference can be attributed to variations in the rate of gelatin cooling during manufacture rather than to the measured heat increase during irradiation.

Highly Sensitive Detection of UV Radiation Using a Uranium Coordination Polymer.

Science.gov (United States)

Liu, Wei; Dai, Xing; Xie, Jian; Silver, Mark A; Zhang, Duo; Wang, Yanlong; Cai, Yawen; Diwu, Juan; Wang, Jian; Zhou, Ruhong; Chai, Zhifang; Wang, Shuao

2018-02-07

The accurate detection of UV radiation is required in a wide range of chemical industries and environmental or biological related applications. Conventional methods taking advantage of semiconductor photodetectors suffer from several drawbacks such as sophisticated synthesis and manufacturing procedure, not being able to measure the accumulated UV dosage as well as high defect density in the material. Searching for new strategies or materials serving as precise UV dosage sensor with extremely low detection limit is still highly desirable. In this work, a radiation resistant uranium coordination polymer [UO 2 (L)(DMF)] (L = 5-nitroisophthalic acid, DMF = N,N-dimethylformamide, denoted as compound 1) was successfully synthesized through mild solvothermal method and investigated as a unique UV probe with the detection limit of 2.4 × 10 -7 J. On the basis of the UV dosage dependent luminescence spectra, EPR analysis, single crystal structure investigation, and the DFT calculation, the UV-induced radical quenching mechanism was confirmed. Importantly, the generated radicals are of significant stability which offers the opportunity for measuring the accumulated UV radiation dosage. Furthermore, the powder material of compound 1 was further upgraded into membrane material without loss in luminescence intensity to investigate the real application potentials. To the best of our knowledge, compound 1 represents the most sensitive coordination polymer based UV dosage probe reported to date.

Improvement of N-phthaloylchitosan based gel polymer electrolyte in dye-sensitized solar cells using a binary salt system.

Science.gov (United States)

Yusuf, S N F; Azzahari, A D; Selvanathan, V; Yahya, R; Careem, M A; Arof, A K

2017-02-10

A binary salt system utilizing lithium iodide (LiI) as the auxiliary component has been introduced to the N-phthaloylchitosan (PhCh) based gel polymer electrolyte consisting of ethylene carbonate (EC), dimethylformamide (DMF), tetrapropylammonium iodide (TPAI), and iodine (I 2 ) in order to improve the performance of dye-sensitized solar cell (DSSC) with efficiency of 6.36%, photocurrent density, J SC of 17.29mAcm -2 , open circuit voltage, V OC of 0.59V and fill factor, FF of 0.62. This efficiency value is an improvement from the 5.00% performance obtained by the DSSC consisting of only TPAI single salt system. The presence of the LiI in addition to the TPAI improves the charge injection rates and increases the iodide contribution to the total conductivity and both factors contribute to the increase in efficiency of the DSSC. The interaction behavior between polymer-plasticizer-salt was thoroughly investigated using EIS, FTIR spectroscopy and XRD. Copyright © 2016 Elsevier Ltd. All rights reserved.

Initial investigation of a novel light-scattering gel phantom for evaluation of optical CT scanners for radiotherapy gel dosimetry

International Nuclear Information System (INIS)

Bosi, Stephen; Naseri, Pourandokht; Puran, Alicia; Davies, Justin; Baldock, Clive

2007-01-01

There is a need for stable gel materials for phantoms used to validate optical computerized tomography (CT) scanners used in conjunction with radiation-induced polymerizing gel dosimeters. Phantoms based on addition of light-absorbing dyes to gelatine to simulate gel dosimeters have been employed. However, to more accurately simulate polymerizing gels one requires phantoms that employ light-scattering colloidal suspensions added to the gel. In this paper, we present the initial results of using an optical CT scanner to evaluate a novel phantom in which radiation-exposed polymer gels are simulated by the addition of colloidal suspensions of varying turbidity. The phantom may be useful as a calibration transfer standard for polymer gel dosimeters. The tests reveal some phenomena peculiar to light-scattering gels that need to be taken into account when calibrating polymer gel dosimeters

How does the chemistry of polymer gel dosimeters affect their performance?

International Nuclear Information System (INIS)

Jirasek, A; McAuley, K B; Lepage, M

2009-01-01

This review article describes the primary chemical processes affecting polymerization in polymer-based radiosensitive gel dosimeters. Furthermore, recently studied environmental factors and gelation processes affecting polymerization and gel dose response are discussed. Finally, the predominant physical factors affecting dose-response sensitivity for each of the three imaging modalities (MRI, Optical CT, x-ray CT) are outlined. Emphasis is concentrated on recent literature in this area, as prior literature was summarized in review articles submitted to DOSGEL 2006 in Sherbrooke (J. Conf. Series, 56, 2006). Discussions from the recent DOSGEL conference (2008) are incorporated into this review.

How does the chemistry of polymer gel dosimeters affect their performance?

Energy Technology Data Exchange (ETDEWEB)

Jirasek, A [Department of Physics and Astronomy, University of Victoria, Victoria BC V8W 3P6 (Canada); McAuley, K B [Department of Chemical Engineering, Queen' s University, Kingston ON K7L 3N6 (Canada); Lepage, M [Centre d' imagerie moleculaire de Sherbrooke, Universite de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke QC J1H 5N4 (Canada)], E-mail: jirasek@uvic.ca, E-mail: kim.mcauley@chee.queensu.ca, E-mail: martin.lepage@usherbrooke.ca

2009-05-01

This review article describes the primary chemical processes affecting polymerization in polymer-based radiosensitive gel dosimeters. Furthermore, recently studied environmental factors and gelation processes affecting polymerization and gel dose response are discussed. Finally, the predominant physical factors affecting dose-response sensitivity for each of the three imaging modalities (MRI, Optical CT, x-ray CT) are outlined. Emphasis is concentrated on recent literature in this area, as prior literature was summarized in review articles submitted to DOSGEL 2006 in Sherbrooke (J. Conf. Series, 56, 2006). Discussions from the recent DOSGEL conference (2008) are incorporated into this review.

Radiation-induced refraction artifacts in the optical CT readout of polymer gel dosimeters

International Nuclear Information System (INIS)

Campbell, Warren G.; Jirasek, Andrew; Wells, Derek M.

2014-01-01

Purpose: The objective of this work is to demonstrate imaging artifacts that can occur during the optical computed tomography (CT) scanning of polymer gel dosimeters due to radiation-induced refractive index (RI) changes in polyacrylamide gels. Methods: A 1 L cylindrical polyacrylamide gel dosimeter was irradiated with 3 × 3 cm 2 square beams of 6 MV photons. A prototype fan-beam optical CT scanner was used to image the dosimeter. Investigative optical CT scans were performed to examine two types of rayline bending: (i) bending within the plane of the fan-beam and (ii) bending out the plane of the fan-beam. To address structured errors, an iterative Savitzky–Golay (ISG) filtering routine was designed to filter 2D projections in sinogram space. For comparison, 2D projections were alternatively filtered using an adaptive-mean (AM) filter. Results: In-plane rayline bending was most notably observed in optical CT projections where rays of the fan-beam confronted a sustained dose gradient that was perpendicular to their trajectory but within the fan-beam plane. These errors caused distinct streaking artifacts in image reconstructions due to the refraction of higher intensity rays toward more opaque regions of the dosimeter. Out-of-plane rayline bending was observed in slices of the dosimeter that featured dose gradients perpendicular to the plane of the fan-beam. These errors caused widespread, severe overestimations of dose in image reconstructions due to the higher-than-actual opacity that is perceived by the scanner when light is bent off of the detector array. The ISG filtering routine outperformed AM filtering for both in-plane and out-of-plane rayline errors caused by radiation-induced RI changes. For in-plane rayline errors, streaks in an irradiated region (>7 Gy) were as high as 49% for unfiltered data, 14% for AM, and 6% for ISG. For out-of-plane rayline errors, overestimations of dose in a low-dose region (∼50 cGy) were as high as 13 Gy for unfiltered

pH and temperature dual-sensitive liposome gel based on novel cleavable mPEG-Hz-CHEMS polymeric vaginal delivery system

Science.gov (United States)

Chen, Daquan; Sun, Kaoxiang; Mu, Hongjie; Tang, Mingtan; Liang, Rongcai; Wang, Aiping; Zhou, Shasha; Sun, Haijun; Zhao, Feng; Yao, Jianwen; Liu, Wanhui

2012-01-01

Background In this study, a pH and temperature dual-sensitive liposome gel based on a novel cleavable hydrazone-based pH-sensitive methoxy polyethylene glycol 2000-hydrazone-cholesteryl hemisuccinate (mPEG-Hz-CHEMS) polymer was used for vaginal administration. Methods The pH-sensitive, cleavable mPEG-Hz-CHEMS was designed as a modified pH-sensitive liposome that would selectively degrade under locally acidic vaginal conditions. The novel pH-sensitive liposome was engineered to form a thermogel at body temperature and to degrade in an acidic environment. Results A dual-sensitive liposome gel with a high encapsulation efficiency of arctigenin was formed and improved the solubility of arctigenin characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry. The dual-sensitive liposome gel with a sol-gel transition at body temperature was degraded in a pH-dependent manner, and was stable for a long period of time at neutral and basic pH, but cleavable under acidic conditions (pH 5.0). Arctigenin encapsulated in a dual-sensitive liposome gel was more stable and less toxic than arctigenin loaded into pH-sensitive liposomes. In vitro drug release results indicated that dual-sensitive liposome gels showed constant release of arctigenin over 3 days, but showed sustained release of arctigenin in buffers at pH 7.4 and pH 9.0. Conclusion This research has shed some light on a pH and temperature dual-sensitive liposome gel using a cleavable mPEG-Hz-CHEMS polymer for vaginal delivery. PMID:22679372

Conducting polymer electrodes for gel electrophoresis.

Directory of Open Access Journals (Sweden)

Katarina Bengtsson

Full Text Available In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that π-conjugated polymers such as poly(3,4-ethylenedioxythiophene (PEDOT can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis systems. In this report, we extend our previous result to gel electrophoresis, and show that electrodes containing PEDOT can be used with a commercial polyacrylamide gel electrophoresis system with minimal impact to the resulting gel image or the ionic transport measured during a separation.

Conducting polymer electrodes for gel electrophoresis.

Science.gov (United States)

Bengtsson, Katarina; Nilsson, Sara; Robinson, Nathaniel D

2014-01-01

In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that π-conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis) systems. In this report, we extend our previous result to gel electrophoresis, and show that electrodes containing PEDOT can be used with a commercial polyacrylamide gel electrophoresis system with minimal impact to the resulting gel image or the ionic transport measured during a separation.

Radiation synthesis of the water-soluble, temperature sensitive polymer, copolymer and study on their properties

International Nuclear Information System (INIS)

Zhai Maolin; Yin Min; Ha Hongfei

1994-01-01

In order to obtain the water-soluble, temperature sensitive polymer and activated copolymer, the radiation polymerization of N-isopropylacrylamide (NIPAAm), radiation copolymerization of NIPAAm and N-acryloxysuccide (NASI) in aqueous solution or in buffer solution (PBS pH = 7.4) have been carried out by γ-rays from 60 Co source at room temperature. The optimum dose range (1-7 kGy), dose rate (>40 Gy/min) and monomer concentration (1%) were chosen through determining the monomer conversion yield and molecular weight (M w = 6.8 x 10 5 ) of product. Synthesis of the reversible linear polymer was performed in tetrahydrofuran (THF) as well. In this way a white powder product could be obtained which possesses of thermally reversible property too, when it was dissolved in water or PBS. The only disadvantages of this method is that the molecular weight of the polymer produced in THF was much lower than that in aqueous solution

Gel Dosimetry Analysis of Gold Nanoparticle Application in Kilovoltage Radiation Therapy

International Nuclear Information System (INIS)

Marques, T; Schwarcke, M; Garrido, C; Zucolot, V; Baffa, O; Nicolucci, P

2010-01-01

In this work gold nanoparticles (AuNP) were embedded in MAGIC-f gel and irradiated in a 250 kV x-ray clinical beam. The signal of non-irradiated gel samples containing AuNPs showed maximum difference of 0.5% related to gel without nanoparticles. Different AuNPs concentrations were studied: 0.10 mM, 0.05 mM and 0.02 mM, presenting dose enhancements of 106%, 90% and 77% respectively. Monte Carlo spectrometry was performed to quantify theoretical changes in photon energy spectrums due to AuNPs presence. Concordance between simulated dose enhancements and gel dosimetry measurements was better than 97% to all concentrations studied. This study evidences that polymer gel dosimetry as a suitable tool to perform dosimetric investigations of nanoparticle applications in Radiation Therapy.

Dose of radiation enhancement, using silver nanoparticles in a human tissue equivalent gel dosimeter.

Science.gov (United States)

Hassan, Muhammad; Waheed, Muhammad Mohsin; Anjum, Muhammad Naeem

2016-01-01

To quantify the radiation dose enhancement in a human tissue-equivalent polymer gel impregnated with silver nanoparticles. The case-control study was conducted at the Bahawalpur Institute of Nuclear Medicine and Oncology, Bahawalpur, Pakistan, in January 2014. Silver nanoparticles used in this study were prepared by wet chemical method. Polymer gel was prepared by known quantity of gelatine, methacrylic acid, ascorbic acid, copper sulphate pentahydrate, hydroquinone and water. Different concentrations of silver nanoparticles were added to the gel during its cooling process. The gel was cooled in six plastic vials of 50ml each. Two vials were used as a control sample while four vials were impregnated with silver nanoparticles. After 22 hours, the vials were irradiated with gamma rays by aCobalt-60 unit. Radiation enhancement was assessed by taking magnetic resonance images of the vials. The images were analysed using Image J software. The dose enhancement factor was 24.17% and 40.49% for 5Gy and 10Gy dose respectively. The dose enhancement factor for the gel impregnated with 0.10mM silver nanoparticles was 32.88% and 51.98% for 5Gy and 10Gy dose respectively. The impregnation of a tissue-equivalent gel with silver nanoparticles resulted in dose enhancement and this effect was magnified up to a certain level with the increase in concentration of silver nanoparticles.

Radiation effects in polyolefins below the gel point as measured by torque rheometry

International Nuclear Information System (INIS)

Markovic, V.; Babic, D.; Silverman, J.

1981-01-01

Torque rheometry is used to obtain information about radiation effects on polymers (crosslinking, degradation) below the gel point. It is shown that rheometric melt viscosity measurements at different shear rates are related changes in the relaxation spectrum. In particular there is a significant radiation effect on low shear rate viscosities but a negligible effect on high shear rate viscosities. The fact that the shear rate in the torque rheometer oscillates about a mean value is utilized to relate torque amplitude measurements to entanglements at zero dose and to crosslink density at absorbed doses below or close to the gel point. (author)

Optical-CT scanning of polymer gels

Energy Technology Data Exchange (ETDEWEB)

Oldham, M [Radiation Oncology Physics, Duke University Medical Center, Duke University, NC (United States)

2004-01-01

The application of optical-CT scanning to achieve accurate high-resolution 3D dosimetry is a subject of current interest. The purpose of this paper is to provide a brief overview of past research and achievements in optical-CT polymer gel dosimetry, and to review current issues and challenges. The origins of optical-CT imaging of light-scattering polymer gels are reviewed. Techniques to characterize and optimize optical-CT performance are presented. Particular attention is given to studies of artifacts in optical-CT imaging, an important area that has not been well studied to date. The technique of optical-CT simulation by Monte-Carlo modeling is introduced as a tool to explore such artifacts. New simulation studies are presented and compared with experimental data.

Optical-CT scanning of polymer gels

International Nuclear Information System (INIS)

Oldham, M

2004-01-01

The application of optical-CT scanning to achieve accurate high-resolution 3D dosimetry is a subject of current interest. The purpose of this paper is to provide a brief overview of past research and achievements in optical-CT polymer gel dosimetry, and to review current issues and challenges. The origins of optical-CT imaging of light-scattering polymer gels are reviewed. Techniques to characterize and optimize optical-CT performance are presented. Particular attention is given to studies of artifacts in optical-CT imaging, an important area that has not been well studied to date. The technique of optical-CT simulation by Monte-Carlo modeling is introduced as a tool to explore such artifacts. New simulation studies are presented and compared with experimental data

Conducting Polymer Electrodes for Gel Electrophoresis

OpenAIRE

Bengtsson, Katarina; Nilsson, Sara; Robinson, Nathaniel D

2014-01-01

In nearly all cases, electrophoresis in gels is driven via the electrolysis of water at the electrodes, where the process consumes water and produces electrochemical by-products. We have previously demonstrated that p-conjugated polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT) can be placed between traditional metal electrodes and an electrolyte to mitigate electrolysis in liquid (capillary electroosmosis/electrophoresis) systems. In this report, we extend our previous result to gel ...

Application of monomer/polymer gel dosimetry to study the effects of tissue inhomogeneities on intensity-modulated radiation therapy (IMRT) dose distributions.

Science.gov (United States)

Vergote, Koen; De Deene, Yves; Claus, Filip; De Gersem, Werner; Van Duyse, Bart; Paelinck, Leen; Achten, Eric; De Neve, Wilfried; De Wagter, Carlos

2003-04-01

When planning an intensity-modulated radiation therapy (IMRT) treatment in a heterogeneous region (e.g. the thorax), the dose computation algorithm of a treatment planning system may need to account for these inhomogeneities in order to obtain a reliable prediction of the dose distribution. An accurate dose verification technique such as monomer/polymer gel dosimetry is suggested to verify the outcome of the planning system. The effects of low-density structures: (a) on narrow high-energy (18 MV) photon beams; and (b) on a class-solution IMRT treatment delivered to a thorax phantom have been examined using gel dosimetry. The used phantom contained air cavities that could be filled with water to simulate a homogeneous or heterogeneous configuration. The IMRT treatment for centrally located lung tumors was delivered on both cases, and gel derived dose maps were compared with computations by both the GRATIS and Helax-TMS planning system. Dose rebuildup due to electronic disequilibrium in a narrow photon beam is demonstrated. The gel measurements showed good agreement with diamond detector measurements. Agreement between measured IMRT dose maps and dose computations was demonstrated by several quantitative techniques. An underdosage of the planning target volume (PTV) was revealed. The homogeneity of the phantom had only a minor influence on the dose distribution in the PTV. An expansion of low-level isodoses in the lung volume was predicted by collapsed cone computations in the heterogeneous case. For the class-solution described, the dose in centrally located mediastinal tumors can be computed with sufficient accuracy, even when neglecting the lower lung density. Polymer gel dosimetry proved to be a valuable technique to verify dose calculation algorithms for IMRT in 3D in heterogeneous configurations.

Poly(vinylpyridine-co-styrene) based in situ cross-linked gel polymer electrolyte for lithium-ion polymer batteries

International Nuclear Information System (INIS)

Oh, Sijin; Kim, Dong Wook; Lee, Changjin; Lee, Myong-Hoon; Kang, Yongku

2011-01-01

A gel polymer electrolyte (GPE) was successfully prepared by means of an in situ cross-linking reaction of poly(2-vinylpyridine-co-styrene) and oligo(ethylene oxide) with epoxide functional groups at 65 °C without using a polymerization initiator. A stable gel polymer electrolyte could be obtained by adding only 1% of a polymer gelator. The ionic conductivity of the GPE containing 99 wt% of liquid electrolyte was measured to be ca. 10 −2 S/cm at the ambient temperature. The ionic conductivity of the resulting GPE was comparable to that of a pure liquid electrolyte. The electrochemical stability window of the prepared gel polymer electrolytes was measured to be 5.2 V. The test cell carried a discharge capacity of 133.2 mAh/g at 0.1 C and showed good cycling performance with negligible capacity fading after the 200th cycle, maintaining 99.5% coulombic efficiency throughout 200 cycles. The resulting gel polymer electrolyte prepared by in situ thermal cross-linking without a polymerization initiator holds promise for application to on the high power lithium-ion polymer batteries.

Radiation effects on the immiscible polymer blend of nylon1010 and high-impact polystyrene (HIPS) I: Gel/dose curves, mathematical expectation theorem and thermal behaviour

International Nuclear Information System (INIS)

Dong, W.; Zhang, W.; Chen, G.; Liu, J.

2000-01-01

This paper studies the radiation properties of the immiscible blend of nylon1010 and HIPS. The gel fraction increased with increasing radiation dose. The network was found mostly in nylon1010, the networks were also found in both nylon1010 and HIPS when the dose reaches 0.85 MGy or more. We used the equation and the modified Zhang-Sun-Qian equation to simulate the relationship with the dose and the sol fraction. The latter equation fits well with these polymer blends and the relationship used by it showed better linearity than the one by the equation. We also studied the conditions of formation of the network by the mathematical expectation theorem for the binary system. Thermal properties of polymer blend were observed by DSC curves. The crystallization temperature decreases with increasing dose because the cross-linking reaction inhibited the crystallization procession and destroyed the crystals. The melting temperature also reduced with increasing radiation dose. The dual melting peak gradually shifted to single peak and the high melting peak disappeared at high radiation dose. However, the radiation-induced crystallization was observed by the heat of fusion increasing at low radiation dose. On the other hand, the crystal will be damaged by radiation. A similar conclusion may be drawn by the DSC traces when the polymer blends were crystallized. When the radiation dose increases, the heat of fusion reduces dramatically and so does the heat of crystallization. (author)

Stereotactic radiosurgery photon field profile dosimetry using conventional dosimeters and polymer gel dosimetry. Analysis and inter-comparison

Energy Technology Data Exchange (ETDEWEB)

Pappas, E; Maris, T G; Zacharopoulou, F; Papadakis, A [Department of Medical Physics, Faculty of Medicine, University of Crete, 711 10 Stavrakia-Heraklion, Crete (Greece); Manolopoulos, S; Green, S [Queen Elizabeth Medical Centre, University Hospital Birmingham NHS Trust, Birmingham B15 2TH (United Kingdom); Wojnecki, C, E-mail: epappas@edu.med.uoc.gr

2009-05-01

Small photon fields are increasingly used in modern radiotherapy and especially in IMRT and SRS/SRT treatments. Accurate beam profile measurements of such beams are crucial for a precise and effective treatment. In this work four different dosimetric methods have been used for profile measurements of three small 6 MV circular fields having diameters of 7.5, 15.0 and 30.0 mm. A small sensitive volume air ion chamber, a diamond detector, a novel silicon-diode array and Vinyl-Pyrrolidone based polymer gel dosimetry. The results of this work reveal the well-known disadvantages and/or problems of the conventional dosimeters for this kind of measurements and support that polymer gel dosimetry may overcome these problems. Conclusively, it is estimated that polymer gels could play an important role towards the minimization of the total SRS/SRT treatment error that is related with small field profile measurements.

Carbon Redox-Polymer-Gel Hybrid Supercapacitors

Science.gov (United States)

Vlad, A.; Singh, N.; Melinte, S.; Gohy, J.-F.; Ajayan, P.M.

2016-01-01

Energy storage devices that provide high specific power without compromising on specific energy are highly desirable for many electric-powered applications. Here, we demonstrate that polymer organic radical gel materials support fast bulk-redox charge storage, commensurate to surface double layer ion exchange at carbon electrodes. When integrated with a carbon-based electrical double layer capacitor, nearly ideal electrode properties such as high electrical and ionic conductivity, fast bulk redox and surface charge storage as well as excellent cycling stability are attained. Such hybrid carbon redox-polymer-gel electrodes support unprecedented discharge rate of 1,000C with 50% of the nominal capacity delivered in less than 2 seconds. Devices made with such electrodes hold the potential for battery-scale energy storage while attaining supercapacitor-like power performances. PMID:26917470

Feasibility study of basic characterization of MAGAT polymer gel using CBCT attached in linear accelerator: Preliminary study

Science.gov (United States)

Sathiyaraj, P.; Samuel, E. James jebaseelan

2018-01-01

The aim of this study is to evaluate the methacrylic acid, gelatin and tetrakis (hydroxymethyl) phosphonium chloride gel (MAGAT) by cone beam computed tomography (CBCT) attached with modern linear accelerator. To compare the results of standard diagnostic computed tomography (CT) with CBCT, different parameters such as linearity, sensitivity and temporal stability were checked. MAGAT gel showed good linearity for both diagnostic CT and CBCT measurements. Sensitivity and temporal stability were also comparable with diagnostic CT measurements. In both the modalities, the sensitivity of the MAGAT increased to 4 days and decreased till the 10th day of post irradiation. Since all measurements (linearity, sensitivity and temporal stability) from diagnostic CT and CBCT were comparable, CBCT could be a potential tool for dose analysis study for polymer gel dosimeter.

An evaluation of the dosimetric performance characteristics of N-vinylpyrrolidone-based polymer gels

Energy Technology Data Exchange (ETDEWEB)

Papadakis, A E [Department of Medical Physics, Faculty of Medicine, University of Crete, PO Box 2208, Iraklion 71003, Crete (Greece); Maris, T G [Department of Medical Physics, Faculty of Medicine, University of Crete, PO Box 2208, Iraklion 71003, Crete (Greece); Zacharopoulou, F [Department of Medical Physics, Faculty of Medicine, University of Crete, PO Box 2208, Iraklion 71003, Crete (Greece); Pappas, E [Department of Medical Physics, Faculty of Medicine, University of Crete, PO Box 2208, Iraklion 71003, Crete (Greece); Zacharakis, G [Institute of Electronic Structure and Laser (IESL), Foundation for Research and Technology-Hellas (FORTH), PO Box 1527, Iraklion, Crete (Greece); Damilakis, J [Department of Medical Physics, Faculty of Medicine, University of Crete, PO Box 2208, Iraklion 71003, Crete (Greece)

2007-08-21

The aim of this work was to investigate the dosimetric performance properties of the N-vinylpyrrolidone argon (VIPAR) based polymer gel as a dosimetric tool in clinical radiotherapy. VIPAR gels with a larger concentration of gelatin than the standard recipe were manufactured and irradiated up to 68 Gy using a 6 and 18 MV linear accelerator. Using MRI, the R2-dose response was recorded at different imaging sessions within a 34 day time period post-irradiation. The R2-dose response was found to be linear between 5 and 68 Gy. Although dose sensitivity did not show significant variation with time, the measured R2-dose values showed an increasing trend, which was less evident beyond 17 days. At one day post-irradiation, calculated dose standard uncertainties at 20 Gy and 56 Gy were 2.2% and 1.7%, providing a dose resolution of 0.45 Gy and 0.97 Gy, respectively. Although these values fulfilled the 2% limit of ICRU, when gels were imaged at one day post-irradiation, it was shown that the temporal evolution of the R2 values deteriorated the per cent standard uncertainty and the dose resolution by {approx}57%, when imaged 17 days post-irradiation. Variation in the coagulation temperature of the gels did not impact the R2-dose sensitivity. This study has shown that the VIPAR gel has the properties of a dosimetric tool required in clinical radiotherapy, especially in applications where a wide dose dynamic range is employed. For results with the lowest per cent uncertainty and the optimum dose resolution, the dosimetry gels used in this work should be MR scanned at one day post-irradiation. Furthermore, a preliminary study on the R2-dose response of a new normoxic N-vinylpyrrolidone-based polymer gel showed that it could potentially replace the traditional VIPAR gel formulation, while preserving the wide dynamic dose response inherent to that monomer.

Conductivity behaviour of polymer gel electrolytes: Role of polymer

Indian Academy of Sciences (India)

Unknown

of a container that can hold a large amount of solvent and as a result possesses the ... having high value of conductivity results in polymer gel electrolytes. They are ..... the availability of free ions provided by the acid. It gene- rally reaches a ...

Surface Decontamination Studies of Cs-137 and Sr-85 Using Polymer Gel

International Nuclear Information System (INIS)

Pham, L.; Nguyen, C.; Nguyen, L.

2015-01-01

Strippable polymer coating is one of the methods for effective surface decontamination to remove isotopes on the contaminated surface. This method is applying in nuclear facilities on the World. In this paper, we present the results obtained in our laboratory from product the polymer coating to apply to remove radioisotopes of "1"3"7Cs and "8"5Sr from surface of glass, stainless steel, mild steel, ceramic, PVC plastic. This polymer gel solution consist of water soluble polymer preferably polyvinyl alcohol (PVA), plasticizing agent (glycerine) and chelating agents, (citric acid) which can be sprayed or pasted on to contaminated surface. After some hours, these gel solutions was dried to form a strong thin film and it was easily peeled off from a contaminated surface with the radioactive isotopes and can be disposed off as radioactive solid waste. In this study infrared spectrophotometry technique was used to examine the interaction of the cesium and strontium ions with polyvinyl alcohol (PVA), polymer gel and the results of the study were also presented. The results showed that decontamination efficiency of "1"3"7Cs and "8"5Sr strongly depended on property, porosity and smoothness of the contaminated surface and obtained from 95-99% on glass and stainless steel, ceramic and PVC plastic surfaces. The decontamination efficiency also depended on activity and coating thickness. Optimization of film thickness is around 0.2 mm. Decontamination efficiency of Polymer gel were compared with Decongel 1101 (product from USA) on surfaces. IR spectra studies indicated that Cs and Sr ions interacted with PVA and citric acid in Polymer gel through cacboxyl (C = O) group. Polymer gel could remove of "1"3"7Cs and "8"5Sr better than PVA gel does because of citric acid, which can form chelating complex with Cs and Sr ion. (author)

Radiation resistant polymers and coatings for nuclear fuel reprocessing plants

International Nuclear Information System (INIS)

Kamachi Mudali, U.; Mallika, C.; Lawrence, Falix

2014-01-01

Polymer based materials are extensively used in the nuclear industry for the reprocessing of spent fuels in highly radioactive and corrosive environment. Hence, these polymer materials are susceptible to damage by ionizing radiation, resulting in the degradation in properties. Polymers containing aromatic molecules generally possess higher resistance to radiation degradation than the aliphatic polymers. For improving the radiation resistance of polymers various methods are reported in the literature. Among the aromatic polymers, polyetheretherketone (PEEK) has the radiation tolerance up to 10 Mega Grey (MGy). To explore the possibility of enhancing the radiation resistance of PEEK, a study was initiated to develop PEEK - ceramic composites and evaluate the effect of radiation on the properties of the composites. PEEK and PEEK - alumina (micron size) composites were irradiated in a gamma chamber using 60 Co source and the degradation in mechanical, structural, electrical and thermal properties, gel fraction, coefficient of friction and morphology were investigated. The degradation in the mechanical properties owing to radiation could be reduced by adding alumina filler to PEEK. Nano alumina filler was observed to be more effective in suppressing the damage caused by radiation on the polymer, when compared to micron alumina filler. For the protection of aluminium components in the manipulators and the rotors and stators of the motors of the centrifugal extractors employed in the plant from the attack by nitric acid vapour, PEEK coating based on liquid dispersion was developed, which has resistance to radiation, chemicals and wear. The effect of radiation and chemical vapour on the properties of the PEEK coating was estimated. The performance of the coating in the plant was evaluated and the coating was found to give adequate protection to the motors of centrifugal extractors against corrosion. (author)

Energy dependence of polymer gels in the orthovoltage energy range

Directory of Open Access Journals (Sweden)

Yvonne Roed

2014-03-01

Full Text Available Purpose: Ortho-voltage energies are often used for treatment of patients’ superficial lesions, and also for small- animal irradiations. Polymer-Gel dosimeters such as MAGAT (Methacrylic acid Gel and THPC are finding increasing use for 3-dimensional verification of radiation doses in a given treatment geometry. For mega-voltage beams, energy dependence of MAGAT has been quoted as nearly energy-independent. In the kilo-voltage range, there is hardly any literature to shade light on its energy dependence.Methods: MAGAT was used to measure depth-dose for 250 kVp beam. Comparison with ion-chamber data showed a discrepancy increasing significantly with depth. An over-response as much as 25% was observed at a depth of 6 cm.Results and Conclusion: Investigation concluded that 6 cm water in the beam resulted in a half-value-layer (HVL change from 1.05 to 1.32 mm Cu. This amounts to an effective-energy change from 81.3 to 89.5 keV. Response measurements of MAGAT at these two energies explained the observed discrepancy in depth-dose measurements. Dose-calibration curves of MAGAT for (i 250 kVp beam, and (ii 250 kVp beam through 6 cm of water column are presented showing significant energy dependence.-------------------Cite this article as: Roed Y, Tailor R, Pinksy L, Ibbott G. Energy dependence of polymer gels in the orthovoltage energy range. Int J Cancer Ther Oncol 2014; 2(2:020232. DOI: 10.14319/ijcto.0202.32 

3D dosimetry study of 188Re liquid balloon for intravascular brachytherapy using BANG polymer gel dosemeters

International Nuclear Information System (INIS)

Wuu, S.; Schiff, P.B.; Maryanski, M.; Liu, T.; Borzillary, S.; Weinberger, J.

2002-01-01

It has been suggested that the combination of intravascular brachytherapy and coronary stent implantation may result in further reduction of restenosis after percutaneous balloon angioplasty. The use of an angioplasty balloon filled with a P 188 Re liquid beta source for intravascular brachytherapy provides the advantage of accurate source positioning and uniform dose distribution to the coronary vessel wall. The effect of source edge and stent on the dose distribution of the target tissue may be clinically important. In BANG gels, the absorbed radiation produces free-radical chain polymerisation of acrylic monomers that are initially dissolved in the gel. The number of polymer particles is proportional to the absorbed dose. In this study, 3D dose distributions are presented for 188 Re balloons, with and without stents, using a prototype He-Ne laser CT scanner and the proprietary BANG polymer gel dosemeters. (author)

Fundamental radiation effect on polymers energy transfer from radiation to polymer

International Nuclear Information System (INIS)

Seguchi, T.

2007-01-01

Polymer modification as cross-link, chain scission, and graft-polymerization by radiation is initiated by the quantum energy transferred from radiation to polymers. The active species for chemical reactions are produced through ionization or activation of polymer molecules for any radiation source. The energy transfer occurs mainly by ionic interaction between radiation and polymer molecule, and the contribution from the collision interaction is miner. The radiation of electromagnetic wave as X-ray or γ-ray generates the energetic electron which induces ionic interaction with polymer molecule. The energy loss profile along the penetration to polymer material is much different among the radiation sources of EB, γ-ray, and ion beams in the macroscopic mechanism. In this article, the behavior of single event, that is, the event induced by one electron, γ-ray, ion, and neutron is described by the macroscopic mechanism and by the microscopic mechanism. (authors)

Sci—Fri PM: Dosimetry—01: Radiation-induced refraction artefacts in the optical CT readout of polymer gel dosimeters

International Nuclear Information System (INIS)

Campbell, Warren G; Jirasek, Andrew; Wells, Derek M

2014-01-01

Polymer gel dosimeters (PGDs) are a desirable tool for the verification of advanced radiotherapy treatments. Fully 3D, deformable, and tissue-equivalent, the PGD polymerizes wherever it absorbs dose. To measure the dose absorbed by a PGD, optical computed tomography (CT) can be used to evaluate, in full 3D, the opacity distribution that coincides with polymerization. In addition to an increase in opacity with dose, an increase in refractive index (RI) is also known to occur in irradiated polymer gels. The increase in RI is slight and was previously assumed insignificant. This work reveals the effects that radiation-induced RI changes can have on the optical CT readout of PGDs. A fan-beam optical CT scanner was used to image a cylindrical PGD irradiated by a pair of 3×3 cm 2 , 6 MV photon beams in an orthogonal arrangement. Investigative scans were performed to evaluate refraction errors occurring: i) within the plane, and ii) out of the plane of the fan-beam. In-plane refraction was shown to cause distinct streaking artefacts along dose gradients (i.e. RI gradients) due to higher intensity rays being refracted into more opaque regions. Out-of-plane refraction was shown to produce severe, widespread artefacts due to rays missing the detector array. An iterative Savitzky-Golay filtering technique was developed to reduce both types of artefacts by specifically targeting structured errors in sinogram space. Results introduce a new category of imaging artefacts to be aware of when using optical CT for PGD readout

γ radiation induced changes in the bioadhesion properties of Ca-alginate gels

International Nuclear Information System (INIS)

Popeski-Dimovski, Riste

2009-01-01

The need for controlled release of drugs and their administration in specific zone of the organism asks for developing of carriers of drugs who will do the job. The two greatest needs, controlled release, and attention on the site, organ, of the organism that's treated its bioadhesion is best done with polymer gels. From the many choices of polymer gels, ether synthetic or natural the Na-alginate gels are the best suited because of their easy of access and good controlled release as being nontoxic to the living organisms and showing promising bioadhesion capability. Because of that examining the possibility for modification of the bioadhesion properties with gamma radiation is of interest. In this work Ca-alginate gels are irradiated with different absorbed doses to see if there will be any changes of the bioadhesion properties. For this mechanical compressibility tests and bioadhesion pull test are conducted on the irradiated samples. The results show that under irradiation gels louse their structural integrity becoming softer but the bioadhesive properties increase. But this increase is very small of up to 20% and its of no interest in practical circumstances where the practice is interested in changes of at least 100% and up, so changing the doses and properties of the gels to increase the bioadhesive properties might be of further interest. (Author)

Radiotherapy gel dosimetry

International Nuclear Information System (INIS)

Baldock, C.

2002-01-01

shapes and sizes while sparing normal tissue. The situation is further complicated if the normal tissues are critical organs or are particularly sensitive to radiation. Radiotherapy techniques employed to obtain a closer conformation of the dose distribution to the tumour volume are referred to as conformal radiotherapy techniques. The clinical implementation of conformal therapy has been delayed by limitations in the verification of conformal dose distributions calculated by treatment planning systems prior to the irradiation of the patient and the verification of complex treatments during its delivery to the patient. There are several aspects of conformal therapy that complicate dose verification. To achieve the dose distributions conforming to complex 3D volumes, high dose gradients arise in the treatment volume. Further, overdose or underdose regions can exist when separate radiation fields are used to deliver additional radiation. These aspects require that practical dose measurement (dosimetry) techniques be able to integrate dose over time and easily measure dose distributions in 3D with high spatial resolution. Traditional dosimeters, such as ion chambers, thermoluminescent dosimeters and radiographic film do not fulfil these requirements. Novel gel dosimetry techniques are being developed in which dose distributions can potentially be determined in vitro in 3D using anthropomorphic phantoms to simulate a clinically irradiated situation. As long ago as the 1950's, radiation-induced colour change in dyes was used to investigate radiation doses in gels. It was subsequently shown that radiation induced changes in nuclear magnetic resonance (NMR) relaxation properties of gels infused with conventional Fricke dosimetry solutions could be measured using magnetic resonance imaging (MRI). In Fricke gels, Fe 2+ ions in ferrous sulphate solutions are usually dispersed throughout a gelatin, agarose or PVA matrix. Radiation-induced changes in the dosimeters are considered to

Method of improving heterogeneous oil reservoir polymer flooding effect by positively-charged gel profile control

Science.gov (United States)

Zhao, Ling; Xia, Huifen

2018-01-01

The project of polymer flooding has achieved great success in Daqing oilfield, and the main oil reservoir recovery can be improved by more than 15%. But, for some strong oil reservoir heterogeneity carrying out polymer flooding, polymer solution will be inefficient and invalid loop problem in the high permeability layer, then cause the larger polymer volume, and a significant reduction in the polymer flooding efficiency. Aiming at this problem, it is studied the method that improves heterogeneous oil reservoir polymer flooding effect by positively-charged gel profile control. The research results show that the polymer physical and chemical reaction of positively-charged gel with the residual polymer in high permeability layer can generate three-dimensional network of polymer, plugging high permeable layer, and increase injection pressure gradient, then improve the effect of polymer flooding development. Under the condition of the same dosage, positively-charged gel profile control can improve the polymer flooding recovery factor by 2.3∼3.8 percentage points. Under the condition of the same polymer flooding recovery factor increase value, after positively-charged gel profile control, it can reduce the polymer volume by 50 %. Applying mechanism of positively-charged gel profile control technology is feasible, cost savings, simple construction, and no environmental pollution, therefore has good application prospect.

Fabrication of Cost-Effective Dye-Sensitized Solar Cells Using Sheet-Like CoS2 Films and Phthaloylchitosan-Based Gel-Polymer Electrolyte

Directory of Open Access Journals (Sweden)

Saradh Prasad

2018-01-01

Full Text Available Platinum-free counter electrodes (CE were developed for use in efficient and cost-effective energy conversion devices, such as dye-sensitized solar cells (DSSCs. Electrochemical deposition of CoS2 on fluorine-doped tin oxide (FTO formed a hierarchical sheet-like structured CoS2 thin film. This film was engaged as a cost-effective platinum-free and high-efficiency CE for DSSCs. High stability was achieved using a phthaloychitosan-based gel-polymer electrolyte as the redox electrolyte. The electrocatalytic performance of the sheet-like CoS2 film was analyzed by electrochemical impedance spectroscopy and cyclic voltammetry. The film displayed improved electrocatalytic behavior that can be credited to a low charge-transfer resistance at the CE/electrolyte boundary and improved exchange between triiodide and iodide ions. The fabricated DSSCs with a phthaloychitosan-based gel-polymer electrolyte and sheet-like CoS2 CE had a power conversion efficiency (PCE, η of 7.29% with a fill factor (FF of 0.64, Jsc of 17.51 mA/cm2, and a Voc of 0.65 V, which was analogous to that of Pt CE (η = 7.82%. The high PCE of the sheet-like CoS2 CE arises from the enhanced FF and Jsc, which can be attributed to the abundant active electrocatalytic sites and enhanced interfacial charge-transfer by the well-organized surface structure.

A 3,3′-dichlorobenzidine-imprinted polymer gel surface plasmon resonance sensor based on template-responsive shrinkage

International Nuclear Information System (INIS)

Zhou, Chunyan; Gao, Jigang; Zhang, Lili; Zhou, Jie

2014-01-01

Graphical abstract: -- Highlights: •Based on template-responsive shrinkage of imprinted gel film, a novel surface plasmon resonance (SPR) sensor is prepared. •The relevant electrochemical parameters are optimized. •The imprinted gel-SPR system has great capability for providing highly sensitive and selective analysis of 3,3′-dichlorobenzidine. •The present SPR sensor was successfully employed to detect 3,3′-dichlorobenzidine in tap water and soil samples. -- Abstract: Molecularly imprinted polymer gel film on the gold substrate of a chip was prepared with minute amount of cross-linker for the fabrication of a surface plasmon resonance (SPR) sensor sensitive to 3,3′-dichlorobenzidine. The molecularly imprinted gel film was anchored on a gold chip by a surface-bound photo-radical initiator. The sensing of 3,3′-dichlorobenzidine is based on responsive shrinkage of the imprinted polymer gel film that is triggered by target binding. This change can improve the responsiveness of the imprinted SPR sensor to 3,3′-dichlorobenzidine. The molecularly imprinted polymer gel film was characterized with contact angle measurements, electrochemical impedance spectroscopy, cyclic voltammogram, swelling measurements and atomic force microscopy. The changes of SPR spectroscopy wavenumber shifts revealed that the imprinted gel sensing film can ‘memorize’ the binding of 3,3′-dichlorobenzidine compared to non-imprinted one. The imprinted gel-SPR sensor showed a linear response in the range of 9.0 × 10 −12 to 5.0 × 10 −10 mol L −1 (R 2 = 0.9998) for the detection of 3,3′-dichlorobenzidine, and it also exhibited high selectivity to 3,3′-dichlorobenzidine compared to its structurally related analogues. We calculated the detection limits to be 0.471 ng L −1 for tap water and 0.772 ng kg −1 for soil based on a signal to noise ratio of 3. The method showed good recoveries and precision for the samples spiked with 3,3′-dichlorobenzidine. This suggest

Radiation Synthesis of PEGDA and Acrylated Palm Oil Nanosized Gel for Bioactives Immobilization

International Nuclear Information System (INIS)

Hamzah, M.Y.; Tajau, R.; Dahlan, K.Z. Mohd; Mahmood, M.H.; Hashim, K.

2010-01-01

The use of microemulsion in the development of nanosized gel based on polyethylene glycol diacrylate (PEGDA) and acrylated palm oil (APO) is demonstrated. PEGDA was solubilized in n-heptane with use of AOT at 0.15M concentration to form reverse micelles, while APO was solubilized with SDS in water to form direct micelles. Both of these systems were depicted by means of ternary phase diagram. These micelles were than irradiated at 1,3,5,10,15 and 30kGy using gamma irradiation or EB to crosslink the entrapped polymer in the micelles. Ionizing radiation was imparted to the emulsions to generate crosslinking reactions in the micelles formed. The nanosized gel was evaluated in terms of particle diameter using dynamic light scattering and the images of the nanosized gel were studied using transmission electron microscopy (TEM). Results show that the size, charge and shape of the particles are influenced by concentration of surfactants and radiation dose. This study showed that this method can be utilized to produce nanosized gel. Future work include the attachment of functional group to the nano sized gel, loading of drug such as curcumin and further characterization using dynamic light scattering. (author)

Radiation Synthesis of PEGDA and Acrylated Palm Oil Nanosized Gel for Bioactives Immobilization

Energy Technology Data Exchange (ETDEWEB)

Hamzah, M. Y.; Tajau, R.; Dahlan, K.Z. Mohd; Mahmood, M. H.; Hashim, K., E-mail: m_yusof@nuclearmalaysia.gov.my [Makmal Nanoteknologi, Blok 64, BTS, Jafan Denghil, Agensi Nuklear Malaysia, Bangi 43000 Kajang, Selangor (Malaysia)

2010-07-01

The use of microemulsion in the development of nanosized gel based on polyethylene glycol diacrylate (PEGDA) and acrylated palm oil (APO) is demonstrated. PEGDA was solubilized in n-heptane with use of AOT at 0.15M concentration to form reverse micelles, while APO was solubilized with SDS in water to form direct micelles. Both of these systems were depicted by means of ternary phase diagram. These micelles were than irradiated at 1,3,5,10,15 and 30kGy using gamma irradiation or EB to crosslink the entrapped polymer in the micelles. Ionizing radiation was imparted to the emulsions to generate crosslinking reactions in the micelles formed. The nanosized gel was evaluated in terms of particle diameter using dynamic light scattering and the images of the nanosized gel were studied using transmission electron microscopy (TEM). Results show that the size, charge and shape of the particles are influenced by concentration of surfactants and radiation dose. This study showed that this method can be utilized to produce nanosized gel. Future work include the attachment of functional group to the nano sized gel, loading of drug such as curcumin and further characterization using dynamic light scattering. (author)

Effect of a novel amphipathic ionic liquid on lithium deposition in gel polymer electrolytes

International Nuclear Information System (INIS)

Choi, Nam-Soon; Koo, Bonjae; Yeon, Jin-Tak; Lee, Kyu Tae; Kim, Dong-Won

2011-01-01

Highlights: · Synthesis of a dimeric ionic liquid. · Gel polymer electrolytes providing uniform lithium deposit pathway. · An amphipathic ionic liquid locates at the interface between an electrolyte-rich phase and a polymer matrix in a gel polymer electrolyte. · The presence of PDMITFSI ionic liquid leads to the suppression of dendritic lithium formation on a lithium metal electrode. - Abstract: A novel dimeric ionic liquid based on imidazolium cation and bis(trifluoromethanesulfonyl) imide (TFSI) anion has been synthesized through a metathesis reaction. Its chemical shift values and thermal properties are identified via 1 H nuclear magnetic resonance (NMR) imaging and differential scanning calorimetry (DSC). The effect of the synthesized dimeric ionic liquid on the interfacial resistance of gel polymer electrolytes is described. Differences in the SEM images of lithium electrodes after lithium deposition with and without the 1,1'-pentyl-bis(2,3-dimethylimidazolium) bis(trifluoromethane-sulfonyl)imide (PDMITFSI) ionic liquid in gel polymer electrolytes are clearly discernible. This occurs because the PDMITFSI ionic liquid with hydrophobic moieties and polar groups modulates lithium deposit pathways onto the lithium metal anode. Moreover, high anodic stability for a gel polymer electrolyte with the PDMITFSI ionic liquid was clearly observed.

Comparative study of nuclear magnetic resonance and UV-visible spectroscopy dose-response of polymer gel based on N-(Isobutoxymethyl) acrylamide

Science.gov (United States)

Lotfy, S.; Basfar, A. A.; Moftah, B.; Al-Moussa, A. A.

2017-12-01

A comparative study of nuclear magnetic resonance and UV-visible spectroscopy of dose-response for polymer gel dosimeters was performed. Dosimeters were prepared using N-(Isobutoxymethyl) acrylamide (NIBMA) as a new monomer via radiation induced polymerization for use in radiotherapy planning. The prepared dosimeters were irradiated with doses up to 30 Gy at a constant dose rate of 600 MU/min. Using a medical linear accelerator at irradiation energies of 6, 10 and 18 MV photon beam. The nuclear magnetic resonance (NMR), via spin-spin relaxation rate (R2) for water proton surrounding the polymer formulation and UV-Visible spectroscopy, via the optical absorbance measurements of irradiated dosimeters at selected wavelengths of 500 nm, was used to investigate the dose response of NIBMAGAT gel dosimeters. Scavenge of oxygen was done using tetrakis (hydroxymethyl) phosphonium chloride (THPC). The THPC optimum concentration in the dosimeters formulations were 5 and 10 mM for the NMR and optical absorbance measurements respectively. The quantitative investigation of the dosimeters components reveals the selective formulations based on 4% w/w gelatin, 1% w/w NIBMA, 3% w/w BisAAm, 5 or 10 mM THPC and 17% w/w glycerol which significantly increase the dosimeters dose response. The prepared dosimeters were found to be dose rate and photon beam irradiation energy independent. The stability study shows no change in the relaxation rate or in the optical absorbance of the gel dosimeters up to 8 days post-irradiation. The prepared polymer gel dosimeters at the energies of 6, 10 and 18 MV photon beam irradiation in the range of 1-30 Gy have the linearity of the dose response function in the case of R2 is better than in the case of absorbance measurements; correlation coefficient (r2) equals 0.995 and 0.991, respectively. Dose sensitivity, R2 of NIBMAGAT dosimeters (0.0775 s-1 Gy-1). The absorption band intensity increases linearly with a dose sensitivity of 0.016 cm-1 Gy-1. The

Radiation synthesis of polymer polyol

International Nuclear Information System (INIS)

Guo Jianmei; Zeng Xinmiao; Zhou Chengfei; Cao Wei; Zhai Tong; Wu Dezhen

2010-01-01

The polymer polyol was synthesized by γ irradiation. The properties of polymer polyol synthesized with different radiation dose were studied. The experiment result showed the radiation dose hadn't significant influence on the hydroxyl value of polymer polyol. The sample with different solid content had different hydroxyl value. When the radiation dose is between 1 to 12 kGy, the viscosity and hydroxyl value of polymer polyol were increased with the increment of radiation dose. When radiation dose is between 1 to 12 kGy, with the increment of radiation dose, viscosity of polymer polyol was rapidly increased, and the content solid of sample has few change. When radiation dose is higher than 20 kGy, the viscosity and hydroxyl value of polymer polyol have gradually increase with the increment of radiation dose. The size of polymer particles is 0.1-0.6 μm. The value of 150 mesh filter was 100%. The polymer polyol may be used as PU foam and elastomer. (authors)

Radiation sterilization of pharmaceuticals and polymers

International Nuclear Information System (INIS)

Gopal, N.G.S.

1978-01-01

Radiation, in the form of high energy electrons as well as gamma radiation, has featured in the last 15 yr as a promising sterilization agent for many heat sensitive and ethylene oxide incompatible pharmaceuticals and polymers of medical usage. This article deals with (i) a comparison of the various methods of sterilization and their shortcomings, (ii) modes of interaction of radiation with matter, (iii) the types of radiation sources in common use, (iv) dosimetry, (v) dose rate effect, (vi) a literature survey of the radiation effect on pharmaceuticals in solid form as well as in aqueous solution and on polymers in the form of plastic medical products and (vii) the evaluation of the irradiated products. The effect of dose rate on the stability of these materials is emphasized. Either very little work has been done on the dose rate effect or the published information is scanty. The literature survey covers the recent period of 5 to 6 years. (author)

Cross-linked Composite Gel Polymer Electrolyte using Mesoporous Methacrylate-Functionalized SiO2 Nanoparticles for Lithium-Ion Polymer Batteries

Science.gov (United States)

Shin, Won-Kyung; Cho, Jinhyun; Kannan, Aravindaraj G.; Lee, Yoon-Sung; Kim, Dong-Won

2016-01-01

Liquid electrolytes composed of lithium salt in a mixture of organic solvents have been widely used for lithium-ion batteries. However, the high flammability of the organic solvents can lead to thermal runaway and explosions if the system is accidentally subjected to a short circuit or experiences local overheating. In this work, a cross-linked composite gel polymer electrolyte was prepared and applied to lithium-ion polymer cells as a safer and more reliable electrolyte. Mesoporous SiO2 nanoparticles containing reactive methacrylate groups as cross-linking sites were synthesized and dispersed into the fibrous polyacrylonitrile membrane. They directly reacted with gel electrolyte precursors containing tri(ethylene glycol) diacrylate, resulting in the formation of a cross-linked composite gel polymer electrolyte with high ionic conductivity and favorable interfacial characteristics. The mesoporous SiO2 particles also served as HF scavengers to reduce the HF content in the electrolyte at high temperature. As a result, the cycling performance of the lithium-ion polymer cells with cross-linked composite gel polymer electrolytes employing methacrylate-functionalized mesoporous SiO2 nanoparticles was remarkably improved at elevated temperatures. PMID:27189842

Radiation synthesis of a water-soluble temperature sensitive polymer, activated copolymer and applications in immobilization of proteins

International Nuclear Information System (INIS)

Zhai Maolin; Ha Hongfei; Wu Jilan

1993-01-01

In this work the radiation polymerization of N-isopropylacrylamide (NIPAAM) in aqueous solutions has been carried out and a water-soluble, temperature sensitive polymer and copolymer were obtained by using γ-rays from Co-60 source at room temperature. We have gained the optimum dose and dose-rate of radiation synthesis of linear polyNIPAAM through determining conversion yield and viscosity. In order to immobilize protein (BSA) and enzyme (HRP) into this water-soluble polymer, we prepared an activated copolymer, poly(N-isopropylacrylamide-co-N-acryloxysuccinimide). The BSA and HRP has been immobilized onto the activated copolymer. The BSA (HRP)/copolymer conjugates still kept the original thermally sensitive properties of the linear polyNIPAAM. The conjugation yield of BSA to the activated copolymer decreased with increasing dose. Immobilized HRP was stable at 0 o C for a long time and has, at least, 4 days stability at room temperature. Immobilized HRP activity was lowered when the temperature was raised. This phenomenon was reversible and the immobilized HRP regained activity. The optimum pH of the immobilized HRP shifted from ca.5 upward to ca. 7. (author)

Radiation-induced coloration of nitro blue tetrazolium gel dosimeter for low dose applications

International Nuclear Information System (INIS)

Abdel-Fattah, A.A.; Beshir, W.B.; Hassan, H.M.; Soliman, Y.S.

2017-01-01

A radiochromic sensor of nitro blue tetrazolium (NBT) in gelatin was evaluated as a new gel dosimeter for radiation applications. The NBT gel has the advantage of visual color change from faint yellow to violet at low absorbed doses (10–1000 Gy). This color change appears as a result of the reduction of NBT to colored formazan then to diformazan species with further increase of absorbed doses. Responses of the gel at different NBT concentrations were analyzed at the absorption maximum centered at 527 nm. An increase of NBT concentrations in the gel enhances the radiation dose sensitivity. Energy dependent study implies the tissue equivalency of the gel in the energy range of 0.15–20 MeV. Dependence of the gel response on irradiation temperature, and color stability before and after irradiation were also studied. The combined uncertainty associated with the dose monitoring (10–1000 Gy) is 6.26% (2σ). Thus, the NBT gel shows its suitability for food irradiation, insect population control, and some food irradiation applications. - Highlights: • Preparation of nitro blue tetrazolium (NBT) gel for the dose range of 10–1000 Gy. • The sensitivity of it increases with increasing NBT concentrations. • The response of irradiated dosimeter is stable after 5 h from irradiation. • The prepared gel dosimeter is a tissue equivalent. • Its combined uncertainty is equal to 6.26% for 10–1000 Gy dose level.

Electroactive polymer gels based on epoxy resin

Science.gov (United States)

Samui, A. B.; Jayakumar, S.; Jayalakshmi, C. G.; Pandey, K.; Sivaraman, P.

2007-04-01

Five types of epoxy gels have been synthesized from common epoxy resins and hardeners. Fumed silica and nanoclay, respectively, were used as fillers and butyl methacrylate/acrylamide were used as monomer(s) for making interpenetrating polymer networks (IPNs) in three compositions. Swelling study, tensile property evaluation, dynamic mechanical thermal analysis, thermo-gravimetric analysis, scanning electron microscopy and electroactive property evaluation were done. The gels have sufficient mechanical strength and the time taken for bending to 20° was found to be 22 min for forward bias whereas it was just 12 min for reverse bias.

Ionic conductivity of polymer gels deriving from alkali metal ionic liquids and negatively charged polyelectrolytes

International Nuclear Information System (INIS)

Ogihara, Wataru; Sun Jiazeng; Forsyth, Maria; MacFarlane, Douglas R.; Yoshizawa, Masahiro; Ohno, Hiroyuki

2004-01-01

We have prepared polymer gel electrolytes with alkali metal ionic liquids (AMILs) that inherently contain alkali metal ions. The AMIL consisted of sulfate anion, imidazolium cation, and alkali metal cation. AMILs were mixed directly with poly(3-sulfopropyl acrylate) lithium salt or poly(2-acrylamido-2-methylpropanesulfonic acid) lithium salt to form polymer gels. The ionic conductivity of these gels decreased with increasing polymer fraction, as in general ionic liquid/polymer mixed systems. At low polymer concentrations, these gels displayed excellent ionic conductivity of 10 -4 to 10 -3 S cm -1 at room temperature. Gelation was found to cause little change in the 7 Li diffusion coefficient of the ionic liquid, as measured by pulse-field-gradient NMR. These data strongly suggest that the lithium cation migrates in successive pathways provided by the ionic liquids

Preparation of micro-porous gel polymer for lithium ion polymer battery

International Nuclear Information System (INIS)

Kim, Je Young; Kim, Seok Koo; Lee, Seung-Jin; Lee, Sang Young; Lee, Hyang Mok; Ahn, Soonho

2004-01-01

We have developed a micro-porous gelling polymer layer which is formed on both the sides of support polyolefin separator with wet or dry processing technique. Morphologies of gel-coated layer are dependent on the compositions and process conditions, such as solvent/non-solvent combination and stretching ratios. The micro-porous gelling layer is used for the assembly of the lithium ion polymer battery of LG Chemical Ltd. The structure of battery is given elsewhere and the battery has excellent discharge performance with 94% of 2C discharge performance at room temperature

Tracking of Nuclear Cable Insulation Polymer Structural Changes using the Gel Fraction and Uptake Factor Method

Energy Technology Data Exchange (ETDEWEB)

Correa, Miguel; Huang, Qian; Fifield, Leonard S.

2018-04-11

Cross-linked polyethylene (XLPE) cable insulation samples were exposed to heat and gamma radiation at a series of temperatures, dose rates, and exposure times to evaluate the effects of these variables on material degradation. The samples were tested using the solvent incubation method to collect gel fraction and uptake factor data in order to assess the crosslinking and chain scission occurring in polymer samples with aging. Consistent with previous reports, gel fraction values were observed to increase and uptake factor values to decrease with radiation and thermal exposure. The trends seen were also more prominent as exposure time increased, suggesting this to be a viable method of tracking structural changes in the XLPE-insulated cable material over extended periods. For the conditions explored, the cable insulation material evaluated did not indicate signs of anomalous aging such as inverse temperature effect in which radiation-induced aging is more severe at lower temperature. Ongoing aging under identical radiation conditions and at lower temperature will further inform conclusions regarding the importance of inverse temperature effects for this material under these conditions.

Raman Spectroscopy of Irradiated Normoxic Polymethacrylic Acid Gel Dosimeter

Energy Technology Data Exchange (ETDEWEB)

Bong, Ji Hye; Kwon, Soo Il; Cho, Yu Ra; Park, Chae Hee; Park, Hyung Wook [Kyonggi University, Suwon (Korea, Republic of); Choi, Kyu Seok; Yu, Soo Chang [Kunsan National University, Gunsan (Korea, Republic of)

2011-02-15

A quantitative analysis of the decreasing rate of the monomer and increasing rate of the polymerization was made by monitoring radiation level increments using Raman spectroscopy within the therapeutic radiation range for a normoxic polymethacrylic acid gel dosimeter. The gel dosimeter was synthesized by stirring materials such as gelatin, distilled water, methacrylic acid, hydroquinone and tetrakis phosphonium chloride at 50 .deg. C, and the synthesized gel was contained in a 10- mm diameter and 32-mm high vial to conduct measurement. 24 hours after gel synthesis, it was irradiated from 0 Gy to 20 Gy by 2 Gy using a Co-60 radiotherapy unit. With use of the Cryo FE-SEM, structural changes in the 0 Gy and 10 Gy gel dosimeters were investigated. The Raman spectra were acquired using 532-nm laser as the excitation source. In accordance with fitting the changes in C-COOH stretching (801 cm{sup -1}), C=C stretching (1639 cm{sup -1}) and vinyl CH{sub 2} stretching (3114 cm{sup -1}) vibrational modes for monomer and CH{sub 2} bending vibrational mode (1451 cm{sup -1}) for polymer, sensitive parameter S for each mode was calculated. The values of S for monomer bands and polymer band were ranged in 6.0 ± 2.6 Gy and 7.2 ± 2.3 Gy, respectively, which shows a relatively good conformity of the decreasing rate of monomer and the increasing rate of polymerization within the range of error.

An investigation of the chemical stability of a monomer/polymer gel dosimeter

International Nuclear Information System (INIS)

De Deene, Y.; De Wagter, C.; De Neve, W.; Achten, E.

2000-01-01

The aim of this work is to investigate the temporal stability of a polyacrylamide gelatin hydrogel used for 3D monomer/polymer gel dosimetry techniques involving different methods of analysis. Long-term instabilities for a similar gel have recently been reported, but differ markedly from those described in this work. Two kinds of long-term instabilities are described. One affects the slope of the dose-R 2 plot and is related to post-irradiation polymerization of the comonomer/polymer aggregates. It is observed that post-irradiation polymerization only lasts 12 hours after irradiation. The other instability affects the intercept of the dose-R 2 plot, lasts for up to 30 days and is related to the gelation process of gelatin. Further studies were performed on gelatin gels of varying compositions to obtain a better understanding of the molecular mechanism that causes the instability due to gelation. The studies included observations of the spin-spin and spin-lattice relaxation rates in combination with diffusion measurements and optical measurements. It is shown that the heating history during the manufacture of the gel affects the absolute R 2 value of the gel but not its variation. The findings presented in this study may help in producing more stable and reproducible monomer/polymer gel dosimeters. (author)

Monte-Carlo based assessment of MAGIC, MAGICAUG, PAGATUG and PAGATAUG polymer gel dosimeters for ovaries and uterus organ dosimetry in brachytherapy, nuclear medicine and Tele-therapy.

Science.gov (United States)

Adinehvand, Karim; Rahatabad, Fereidoun Nowshiravan

2018-06-01

Calculation of 3D dose distribution during radiotherapy and nuclear medicine helps us for better treatment of sensitive organs such as ovaries and uterus. In this research, we investigate two groups of normoxic dosimeters based on meta-acrylic acid (MAGIC and MAGICAUG) and polyacrylamide (PAGATUG and PAGATAUG) for brachytherapy, nuclear medicine and Tele-therapy in their sensitive and critical role as organ dosimeters. These polymer gel dosimeters are compared with soft tissue while irradiated by different energy photons in therapeutic applications. This comparison has been simulated by Monte-Carlo based MCNPX code. ORNL phantom-Female has been used to model the critical organs of kidneys, ovaries and uterus. Right kidney is proposed to be the source of irradiation and another two organs are exposed to this irradiation. Effective atomic numbers of soft tissue, MAGIC, MAGICAUG, PAGATUG and PAGATAUG are 6.86, 7.07, 6.95, 7.28, and 7.07 respectively. Results show the polymer gel dosimeters are comparable to soft tissue for using in nuclear medicine and Tele-therapy. Differences between gel dosimeters and soft tissue are defined as the dose responses. This difference is less than 4.1%, 22.6% and 71.9% for Tele-therapy, nuclear medicine and brachytherapy respectively. The results approved that gel dosimeters are the best choice for ovaries and uterus in nuclear medicine and Tele-therapy respectively. Due to the slight difference between the effective atomic numbers of these polymer gel dosimeters and soft tissue, these polymer gels are not suitable for brachytherapy since the dependence of photon interaction to atomic number, for low energy brachytherapy, had been so effective. Also this dependence to atomic number, decrease for photoelectric and increase for Compton. Therefore polymer gel dosimeters are not a good alternative to soft tissue replacement in brachytherapy. Copyright © 2018 Elsevier B.V. All rights reserved.

Performance evaluation of an improved optical computed tomography polymer gel dosimeter system for 3D dose verification of static and dynamic phantom deliveries

International Nuclear Information System (INIS)

Lopatiuk-Tirpak, O.; Langen, K. M.; Meeks, S. L.; Kupelian, P. A.; Zeidan, O. A.; Maryanski, M. J.

2008-01-01

The performance of a next-generation optical computed tomography scanner (OCTOPUS-5X) is characterized in the context of three-dimensional gel dosimetry. Large-volume (2.2 L), muscle-equivalent, radiation-sensitive polymer gel dosimeters (BANG-3) were used. Improvements in scanner design leading to shorter acquisition times are discussed. The spatial resolution, detectable absorbance range, and reproducibility are assessed. An efficient method for calibrating gel dosimeters using the depth-dose relationship is applied, with photon- and electron-based deliveries yielding equivalent results. A procedure involving a preirradiation scan was used to reduce the edge artifacts in reconstructed images, thereby increasing the useful cross-sectional area of the dosimeter by nearly a factor of 2. Dose distributions derived from optical density measurements using the calibration coefficient show good agreement with the treatment planning system simulations and radiographic film measurements. The feasibility of use for motion (four-dimensional) dosimetry is demonstrated on an example comparing dose distributions from static and dynamic delivery of a single-field photon plan. The capability to visualize three-dimensional dose distributions is also illustrated

The role of the solvent in PMMA gel polymer\

Czech Academy of Sciences Publication Activity Database

Vondrák, J.; Musil, M.; Sedlaříková, M.; Kořínek, Radim; Bartušek, Karel; Fedorková, A.

2016-01-01

Roč. 2, č. 1 (2016), s. 6-12 E-ISSN 2300-3545 R&D Projects: GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : gel polymer electrolyte * TGA * NMR spectroscopy * conductivity * sodium polymer electrolyte Subject RIV: BH - Optics, Masers, Lasers https://www.degruyter.com/view/j/eetech.2016.2.issue-1/eetech-2016-0002/eetech-2016-0002.xml

Optical CT evaluation on normoxic polymer gel dosimeter

International Nuclear Information System (INIS)

Samuel, E. James Jebaseelan

2013-01-01

Optical computed tomography has been shown to be a potentially useful imaging tool for the radiation therapy physicists. In radiation therapy, researchers have used optical CT for the readout of 3D dosimeters. The purpose of this paper is to explicate the initial evaluation of a newly fabricated laser CT scanner for '3D gel dosimetry' which works in the first generation principle. 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 of photon take place. The optical attenuation coefficient of the laser can be obtained by measuring its intensity after passing through the gel by a sensor.The scanner motion is controlled by the program written in Microsoft Visual C++. Reconstruction and data analysis on the irradiated gel phantom is performed by suitable algorithm using Matlab software. (author)

The study of polymeric hydro-gels with unique properties obtained by polymerization with gamma radiation processing

International Nuclear Information System (INIS)

Dragusin, M.

1995-01-01

This thesis presents the work carried out on polymeric hydro-gels obtained by radiation processing using 60 Co gamma rays from the irradiation facility IETI-10.000 (10 k Ci), and on the polymeric hydro-gels obtained by irradiation with the electron beams from a linear accelerator (6 MeV). The aim of the study was to determine the effect of the rate dose and total dose absorbed in the materials. There are presented the preparation methods of homo- and co-polymer hydro-gels (acrylics, namely anionic and neutral monomers (acrylamide, acrylic acid, vinyl acetate) and cationic monomers (di-methyl di-allyl ammonium chloride)) such as floculants, additives, absorbers, etc. Concerning with these we have analysed the preparation methods, the mechanical, thermal, diffusivity, and swelling properties of polymeric hydro-gels in a large variety of gels of type I or II. The technological aspects and end use were studied in connection with the characteristics of the radiation processing of these hydro-gels as a function of chemical composition rate and absorbed dose, swelling degree (low and very high hydro-soluble), mechanical and diffusional properties. (author) 33 figs., 12 tabs., 101 refs

High sensitive radiation detector for radiology dosimetry

Energy Technology Data Exchange (ETDEWEB)

Valente, M.; Malano, F. [Instituto de Fisica Enrique Gaviola, Oficina 102 FaMAF - UNC, Av. Luis Medina Allende, Ciudad Universitaria, 5000 Cordoba (Argentina); Molina, W.; Vedelago, J., E-mail: valente@famac.unc.edu.ar [Laboratorio de Investigaciones e Instrumentacion en Fisica Aplicada a la Medicina e Imagenes por Rayos X, Laboratorio 448 FaMAF - UNC, Ciudad Universitaria, 5000 Cordoba (Argentina)

2014-08-15

Fricke solution has a wide range of applications as radiation detector and dosimetry. It is particularly appreciated in terms of relevant comparative advantages, like tissue equivalence when prepared in aqueous media like gel matrix, continuous mapping capability, dose rate recorded and incident direction independence as well as linear dose response. This work presents the development and characterization of a novel Fricke gel system, based on modified chemical compositions making possible its application in clinical radiology. Properties of standard Fricke gel dosimeter for high dose levels are used as starting point and suitable chemical modifications are introduced and carefully investigated in order to attain high resolution for low dose ranges, like those corresponding to radiology interventions. The developed Fricke gel radiation dosimeter system achieves the expected typical dose dependency, actually showing linear response in the dose range from 20 up to 4000 mGy. Systematic investigations including several chemical compositions are carried out in order to obtain a good enough dosimeter response for low dose levels. A suitable composition among those studied is selected as a good candidate for low dose level radiation dosimetry consisting on a modified Fricke solution fixed to a gel matrix containing benzoic acid along with sulfuric acid, ferrous sulfate, xylenol orange and ultra-pure reactive grade water. Dosimeter samples are prepared in standard vials for its in phantom irradiation and further characterization by spectrophotometry measuring visible light transmission and absorbance before and after irradiation. Samples are irradiated by typical kV X-ray tubes and calibrated Farmer type ionization chamber is used as reference to measure dose rates inside phantoms in at vials locations. Once sensitive material composition is already optimized, dose-response curves show significant improvement regarding overall sensitivity for low dose levels. According to

High sensitive radiation detector for radiology dosimetry

International Nuclear Information System (INIS)

Valente, M.; Malano, F.; Molina, W.; Vedelago, J.

2014-08-01

Fricke solution has a wide range of applications as radiation detector and dosimetry. It is particularly appreciated in terms of relevant comparative advantages, like tissue equivalence when prepared in aqueous media like gel matrix, continuous mapping capability, dose rate recorded and incident direction independence as well as linear dose response. This work presents the development and characterization of a novel Fricke gel system, based on modified chemical compositions making possible its application in clinical radiology. Properties of standard Fricke gel dosimeter for high dose levels are used as starting point and suitable chemical modifications are introduced and carefully investigated in order to attain high resolution for low dose ranges, like those corresponding to radiology interventions. The developed Fricke gel radiation dosimeter system achieves the expected typical dose dependency, actually showing linear response in the dose range from 20 up to 4000 mGy. Systematic investigations including several chemical compositions are carried out in order to obtain a good enough dosimeter response for low dose levels. A suitable composition among those studied is selected as a good candidate for low dose level radiation dosimetry consisting on a modified Fricke solution fixed to a gel matrix containing benzoic acid along with sulfuric acid, ferrous sulfate, xylenol orange and ultra-pure reactive grade water. Dosimeter samples are prepared in standard vials for its in phantom irradiation and further characterization by spectrophotometry measuring visible light transmission and absorbance before and after irradiation. Samples are irradiated by typical kV X-ray tubes and calibrated Farmer type ionization chamber is used as reference to measure dose rates inside phantoms in at vials locations. Once sensitive material composition is already optimized, dose-response curves show significant improvement regarding overall sensitivity for low dose levels. According to

Manufacturing of different gel detectors and their calibration for spatial radiation dose measurements

International Nuclear Information System (INIS)

Bero, M.

2008-05-01

Three types of gel dosemeter have been made and their most important properties for radiation dosimetry were studied. The comparison between the three categories helps to widen knowledge in each of these detectors and to establish a method for the preparation as well as testing of this radiation sensitive materials. Experiments show the technical application possibility for using these gel detectors to measure the spatial radiation dose distribution in the range of doses given for cancer treatment. The experimental results give some important characteristic for the three gel dosemeter used in comparison to that of the traditional dosimetry systems. It also shows the simplicity of manufacturing the dosemeter from low cost materials and its radiation response to ionizing. The relationships between the dosemeter response and the dose rate as well as the radiation energy were also investigated. Important subjects that have been also taken into consideration are the effects of ambient conditions and storage likelihood of the studied materials. Recommendation was made for the use of these materials in practical applications and for handling as well as their long term storage possibility. (author)

Incorporating allylated lignin-derivatives in thiol-ene gel-polymer electrolytes.

Science.gov (United States)

Baroncini, Elyse A; Stanzione, Joseph F

2018-07-01

Growing environmental and economic concerns as well as the uncertainty that accompanies finite petrochemical resources contributes to the increase in research and development of bio-based, renewable polymers. Concurrently, industrial and consumer demand for smaller, safer, and more flexible technologies motivates a global research effort to improve electrolytic polymer separators in lithium-ion batteries. To incorporate the aromatic structural advantages of lignin, a highly abundant and renewable resource, into gel-polymer electrolytes, lignin-derived molecules, vanillyl alcohol and gastrodigenin are functionalized and UV-polymerized with multi-functional thiol monomers. The resulting thin, flexible, polymer films possess glass transition temperatures ranging from -42.1°C to 0.3°C and storage moduli at 25°C ranging from 1.90MPa to 10.08MPa. The crosslinked polymer films swollen with electrolyte solution impart conductivities in the range of 7.04×10 -7 to 102.73×10 -7 Scm -1 . Thiol molecular weight has the most impact on the thermo-mechanical properties of the resulting films while polymer crosslink density has the largest effect on conductivity. The conducting abilities of the bio-based gel-polymer electrolytes in this study prove the viability of lignin-derived feedstock for use in lithium-ion battery applications and reveal structurally and thermally desirable traits for future work. Copyright © 2018 Elsevier B.V. All rights reserved.

A novel and high-effective redox-mediated gel polymer electrolyte for supercapacitor

International Nuclear Information System (INIS)

Ma, Guofu; Feng, Enke; Sun, Kanjun; Peng, Hui; Li, Jiajia; Lei, Ziqiang

2014-01-01

Graphical abstract: - Highlights: • Alkali and P-phenylenediamine doped polyvinyl alcohol gel electrolyte is prepared. • The PVA-KOH-PPD gel electrolyte can also be used as separator. • The introduction of PPD increases the ionic conductivity of electrolyte. • The supercapacitor exhibits flexible and high energy density. - Abstract: A supercapacitor utilize a novel redox-mediated gel polymer (PVA-KOH-PPD) as electrolyte and separator, and activated carbon as electrodes is assembled. The PVA-KOH-PPD gel polymer as potential electrolyte for supercapacitor is investigated by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy techniques. It is found that the supercapacitor exhibits high ionic conductivity (25 mS cm −1 ), large electrode specific capacitance (611 F g −1 ) and high energy density (82.56 Wh kg −1 ). The high performance is attributed to the addition of quick redox reactions at the electrolyte|electrode interface as PPD undergoes a two-proton/two-electron reduction and oxidation during cycling. Furthermore, the supercapacitor with PVA-KOH-PPD gel polymer shows excellent charge-discharge stability, after 1000 charge-discharge cycles, the supercapacitor still retains a high electrode specific capacitance of 470 F g −1 . It is believed that the idea using redox mediator has a good prospect for improving the performances of supercapacitors

EGSnrc calculated and MRI-polymer gel dosimeter measured dose distribution of gamma knife in presence of inhomogeneities

International Nuclear Information System (INIS)

Allahverdi Pourfallah, T.; Allahverdi, M.; Riahi Alam, N.; Ay, M.; Zahmatkesh, M.; Ibbott, J.S.

2008-01-01

Stereotactic gamma-knife radiosurgery plays an important role in managing small intracranial brain lesions. Currently, polymer gel dosimetry is still the only dosimetry method for directly measuring three-dimensional dose distributions. polymer gel dosimeters are tissue equivalent and can act as a phantom material. In this study effects of inhomogeneities on those distributions have been investigated using both EGSnrc calculation and PAGAT polymer gel dosimeter. (author)

SU-E-T-243: MonteCarlo Simulation Study of Polymer and Radiochromic Gel for Three-Dimensional Proton Dose Distribution

International Nuclear Information System (INIS)

Park, M; Jung, H; Kim, G; Ji, Y; Kim, K; Park, S

2014-01-01

Purpose: To estimate the three dimensional dose distributions in a polymer gel and a radiochromic gel by comparing with the virtual water phantom exposed to proton beams by applying Monte Carlo simulation. Methods: The polymer gel dosimeter is the compositeness material of gelatin, methacrylic acid, hydroquinone, tetrakis, and distilled water. The radiochromic gel is PRESAGE product. The densities of polymer and radiochromic gel were 1.040 and 1.0005 g/cm3, respectively. The shape of water phantom was a hexahedron with the size of 13 × 13 × 15 cm3. The proton beam energies of 72 and 116 MeV were used in the simulation. Proton beam was directed to the top of the phantom with Z-axis and the shape of beam was quadrangle with 10 × 10 cm2 dimension. The Percent depth dose and the dose distribution were evaluated for estimating the dose distribution of proton particle in two gel dosimeters, and compared with the virtual water phantom. Results: The Bragg-peak for proton particles in two gel dosimeters was similar to the virtual water phantom. Bragg-peak regions of polymer gel, radiochromic gel, and virtual water phantom were represented in the identical region (4.3 cm) for 72 MeV proton beam. For 116 MeV proton beam, the Bragg-peak regions of polymer gel, radiochromic gel, and virtual water phantom were represented in 9.9, 9.9 and 9.7 cm, respectively. The dose distribution of proton particles in polymer gel, radiochromic gel, and virtual water phantom was approximately identical in the case of 72 and 116 MeV energies. The errors for the simulation were under 10%. Conclusion: This work indicates the evaluation of three dimensional dose distributions by exposing proton particles to polymer and radiochromic gel dosimeter by comparing with the water phantom. The polymer gel and the radiochromic gel dosimeter show similar dose distributions for the proton beams

Synthesis of polymer gel electrolyte with high molecular weight poly(methyl methacrylate)-clay nanocomposite

International Nuclear Information System (INIS)

Meneghetti, Paulo; Qutubuddin, Syed; Webber, Andrew

2004-01-01

Polymer nanocomposite gel electrolytes consisting of high molecular weight poly(methyl methacrylate) PMMA-clay nanocomposite, ethylene carbonate (EC)/propylene carbonate (PC) as plasticizer, and LiClO 4 electrolyte are reported. Montmorillonite clay was ion exchanged with a zwitterionic surfactant (octadecyl dimethyl betaine) and dispersed in methyl methacrylate, which was then polymerized to synthesize PMMA-clay nanocomposites. The nanocomposite was dissolved in a mixture of EC/PC with LiClO 4 , heated and pressed to obtain polymer gel electrolyte. X-ray diffraction (XRD) of the gels indicated intercalated clay structure with d-spacings of 2.85 and 1.40 nm. In the gel containing plasticizer, the clay galleries shrink suggesting intercalation rather than partial exfoliation observed in the PMMA-clay nanocomposite. Ionic conductivity varied slightly and exhibited a maximum value of 8 x 10 -4 S/cm at clay content of 1.5 wt.%. The activation energy was determined by modeling the conductivity with a Vogel-Tamman-Fulcher expression. The clay layers are primarily trapped inside the polymer matrix. Consequently, the polymer does not interact significantly with LiClO 4 electrolyte as shown by FTIR. The presence of the clay increased the glass transition temperature (Tg) of the gel as determined by differential scanning calorimetry. The PMMA nanocomposite gel electrolyte shows a stable lithium interfacial resistance over time, which is a key factor for use in electrochemical applications

Fricke Xylenol Gel characterization at megavoltage radiation energy

Energy Technology Data Exchange (ETDEWEB)

Del Lama, Lucas Sacchini, E-mail: lucasdellama@gmail.com [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, DF-FFCLRP/USP, Avenida Bandeirantes, n" o 3900, Monte Alegre, CEP: 14040-901, Ribeirão Preto, SP (Brazil); Petchevist, Paulo César Dias [Oncoville, Centro de Excelência em Radioterapia em Curitiba, Rodovia BR-277, n" o 1437, Ecoville, CEP: 82305-100, Curitiba, PR (Brazil); Almeida, Adelaide de [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, DF-FFCLRP/USP, Avenida Bandeirantes, n" o 3900, Monte Alegre, CEP: 14040-901, Ribeirão Preto, SP (Brazil)

2017-03-01

Accurate determination of absorbed dose is of great importance in every medical application of ionizing radiation, mainly when involving biological tissues. Among different types of dosimeters, the ferrous sulfate chemical solution, known as Fricke solution, can be detached, due to its accuracy, reproducibility and linearity, been used in radiation dosimetry for over 50 years. Besides these characteristics, the Fricke Xylenol Gel (FXG), became one of the most known dosimeters for absorbed dose spatial distribution because of its high spatial resolution. In this work, we evaluated the FXG dosimeter taking into account different preparation recipes, in order to characterize its response in terms of absorbed dose range, linearity, sensitivity and fading.

Fricke Xylenol Gel characterization at megavoltage radiation energy

International Nuclear Information System (INIS)

o 3900, Monte Alegre, CEP: 14040-901, Ribeirão Preto, SP (Brazil))" data-affiliation=" (Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, DF-FFCLRP/USP, Avenida Bandeirantes, no 3900, Monte Alegre, CEP: 14040-901, Ribeirão Preto, SP (Brazil))" >Del Lama, Lucas Sacchini; o 1437, Ecoville, CEP: 82305-100, Curitiba, PR (Brazil))" data-affiliation=" (Oncoville, Centro de Excelência em Radioterapia em Curitiba, Rodovia BR-277, no 1437, Ecoville, CEP: 82305-100, Curitiba, PR (Brazil))" >Petchevist, Paulo César Dias; o 3900, Monte Alegre, CEP: 14040-901, Ribeirão Preto, SP (Brazil))" data-affiliation=" (Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, DF-FFCLRP/USP, Avenida Bandeirantes, no 3900, Monte Alegre, CEP: 14040-901, Ribeirão Preto, SP (Brazil))" >Almeida, Adelaide de

2017-01-01

Accurate determination of absorbed dose is of great importance in every medical application of ionizing radiation, mainly when involving biological tissues. Among different types of dosimeters, the ferrous sulfate chemical solution, known as Fricke solution, can be detached, due to its accuracy, reproducibility and linearity, been used in radiation dosimetry for over 50 years. Besides these characteristics, the Fricke Xylenol Gel (FXG), became one of the most known dosimeters for absorbed dose spatial distribution because of its high spatial resolution. In this work, we evaluated the FXG dosimeter taking into account different preparation recipes, in order to characterize its response in terms of absorbed dose range, linearity, sensitivity and fading.

Locally Targeted Delivery of a Micron-Size Radiation Therapy Source Using Temperature-Sensitive Hydrogel

Energy Technology Data Exchange (ETDEWEB)

Kim, Yusung, E-mail: yusung-kim@uiowa.edu [Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa (United States); Seol, Dong Rim [Department of Orthopaedic Surgery, The University of Iowa, Iowa City, Iowa (United States); Mohapatra, Sucheta [Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa (United States); Sunderland, John J. [Department of Radiology, The University of Iowa, Iowa City, Iowa (United States); Schultz, Michael K. [Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa (United States); Department of Radiology, The University of Iowa, Iowa City, Iowa (United States); Domann, Frederick E. [Department of Radiation Oncology, The University of Iowa, Iowa City, Iowa (United States); Department of Surgery, The University of Iowa, Iowa City, Iowa (United States); Lim, Tae-Hong [Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa (United States)

2014-04-01

Purpose: To propose a novel radiation therapy (RT) delivery modality: locally targeted delivery of micron-size RT sources by using temperature-sensitive hydrogel (RT-GEL) as an injectable vehicle. Methods and Materials: Hydrogel is a water-like liquid at room temperature but gels at body temperature. Two US Food and Drug Administration-approved polymers were synthesized. Indium-111 (In-111) was used as the radioactive RT-GEL source. The release characteristics of In-111 from polymerized RT-GEL were evaluated. The injectability and efficacy of RT-GEL delivery to human breast tumor were tested using animal models with control datasets of RT-saline injection. As proof-of-concept studies, a total of 6 nude mice were tested by injecting 4 million tumor cells into their upper backs after a week of acclimatization. Three mice were injected with RT-GEL and 3 with RT-saline. Single-photon emission computed tomography (SPECT) and CT scans were performed on each mouse at 0, 24, and 48 h after injection. The efficacy of RT-GEL was determined by comparison with that of the control datasets by measuring kidney In-111 accumulation (mean nCi/cc), representing the distant diffusion of In-111. Results: RT-GEL was successfully injected into the tumor by using a 30-gauge needle. No difficulties due to polymerization of hydrogel during injection and intratumoral pressure were observed during RT-GEL injection. No back flow occurred for either RT-GEL or RT-saline. The residual tumor activities of In-111 were 49% at 24 h (44% at 48 h, respectively) for RT-GEL and 29% (22%, respectively) for RT-saline. Fused SPECT-CT images of RT-saline showed considerable kidney accumulation of In-111 (2886%, 261%, and 262% of RT-GEL at 0, 24, and 48 h, respectively). Conclusions: RT-GEL was successfully injected and showed much higher residual tumor activity: 170% (200%, respectively), than that of RT-saline at 24 h (48 h, respectively) after injection with a minimal accumulation of In-111 to the

Solid-state supercapacitors with ionic liquid based gel polymer electrolyte: Effect of lithium salt addition

Science.gov (United States)

Pandey, G. P.; Hashmi, S. A.

2013-12-01

Performance characteristics of the solid-state supercapacitors fabricated with ionic liquid (IL) incorporated gel polymer electrolyte and acid treated multiwalled carbon nanotube (MWCNT) electrodes have been studied. The effect of Li-salt (LiPF6) addition in the IL (1-ethyl-3-methylimidazolium tris(pentafluoroethyl) trifluorophosphate, EMImFAP) based gel electrolyte on the performance of supercapacitors has been specifically investigated. The LiPF6/IL/poly(vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP) gel electrolyte film possesses excellent electrochemical window of 4 V (from -2.0 to 2.0 V), high ionic conductivity ∼2.6 × 10-3 S cm-1 at 20 °C and high enough thermal stability. The comparative performance of supercapacitors employing electrolytes with and without lithium salt has been evaluated by impedance spectroscopy and cyclic voltammetric studies. The acid-treated MWCNT electrodes show specific capacitance of ∼127 F g-1 with IL/LiPF6 containing gel polymer electrolyte as compared to that with the gel polymer electrolyte without Li-salt, showing the value of ∼76 F g-1. The long cycling stability of the solid state supercapacitor based on the Li-salt containing gel polymer electrolyte confirms the electrochemical stability of the electrolyte.

Polymer sol-gel composite inverse opal structures.

Science.gov (United States)

Zhang, Xiaoran; Blanchard, G J

2015-03-25

We report on the formation of composite inverse opal structures where the matrix used to form the inverse opal contains both silica, formed using sol-gel chemistry, and poly(ethylene glycol), PEG. We find that the morphology of the inverse opal structure depends on both the amount of PEG incorporated into the matrix and its molecular weight. The extent of organization in the inverse opal structure, which is characterized by scanning electron microscopy and optical reflectance data, is mediated by the chemical bonding interactions between the silica and PEG constituents in the hybrid matrix. Both polymer chain terminus Si-O-C bonding and hydrogen bonding between the polymer backbone oxygens and silanol functionalities can contribute, with the polymer mediating the extent to which Si-O-Si bonds can form within the silica regions of the matrix due to hydrogen-bonding interactions.

Implementation of MRI gel dosimetry in radiation therapy

International Nuclear Information System (INIS)

Baeck, S.Aa.J.

1998-12-01

Gel dosimetry was used together with magnetic resonance imaging (MRI) to measure three-dimensional absorbed dose distributions in radiation therapy. Two different dosimeters were studied: ferrous- and monomer gel, based on the principles of radiation-induced oxidation and polymerisation, respectively. Single clinical electron and photon beams were evaluated and gel dose distributions were mainly within 2% of conventional detector results. The ferrous-gel was also used for clinical proton beams. A decrease in signal per absorbed dose was found close to the end of the range of the protons (15-20%). This effect was explained as a linear energy transfer dependence, further supported with Monte Carlo simulations. A method for analysing and comparing data from treatment planning system (TPS) and gel measurements was developed. The method enables a new pixel by pixel evaluation, isodose comparison and dose volume histogram verification. Two standard clinical radiation therapy procedures were examined using the developed TPS verification method. The treatment regimes included several beams of different radiation qualities. The TPS calculated data were in very good agreement with the dose distribution measured by the ferrous-gel. However, in a beam abutment region, larger dose difference was found. Beam adjustment errors and a minor TPS underestimation of the lateral scatter contribution outside the primary electron beam may explain the discrepancy. The overall uncertainty in the ferrous-gel dose determination was considerably reduced using an optimised MRI acquisition protocol and a new MRI scanner. The relative dose uncertainty was found to be better than 3.3% for all dose levels (95% confidence level). Using the method developed for comparing measured gel data with calculated treatment plans, the gel dosimetry method was proven to be a useful tool for radiation treatment planning verification

Implementation of MRI gel dosimetry in radiation therapy

Energy Technology Data Exchange (ETDEWEB)

Baeck, S.Aa.J

1998-12-01

Gel dosimetry was used together with magnetic resonance imaging (MRI) to measure three-dimensional absorbed dose distributions in radiation therapy. Two different dosimeters were studied: ferrous- and monomer gel, based on the principles of radiation-induced oxidation and polymerisation, respectively. Single clinical electron and photon beams were evaluated and gel dose distributions were mainly within 2% of conventional detector results. The ferrous-gel was also used for clinical proton beams. A decrease in signal per absorbed dose was found close to the end of the range of the protons (15-20%). This effect was explained as a linear energy transfer dependence, further supported with Monte Carlo simulations. A method for analysing and comparing data from treatment planning system (TPS) and gel measurements was developed. The method enables a new pixel by pixel evaluation, isodose comparison and dose volume histogram verification. Two standard clinical radiation therapy procedures were examined using the developed TPS verification method. The treatment regimes included several beams of different radiation qualities. The TPS calculated data were in very good agreement with the dose distribution measured by the ferrous-gel. However, in a beam abutment region, larger dose difference was found. Beam adjustment errors and a minor TPS underestimation of the lateral scatter contribution outside the primary electron beam may explain the discrepancy. The overall uncertainty in the ferrous-gel dose determination was considerably reduced using an optimised MRI acquisition protocol and a new MRI scanner. The relative dose uncertainty was found to be better than 3.3% for all dose levels (95% confidence level). Using the method developed for comparing measured gel data with calculated treatment plans, the gel dosimetry method was proven to be a useful tool for radiation treatment planning verification 103 refs, 20 figs, 6 tabs

Extraction of americium (III) by thermosensitive polymer gel copolymerized with acidic phosphorus compound

International Nuclear Information System (INIS)

Takeshita, Kenji; Nakano, Yoshio; Matsumura, Tatsuro

2001-01-01

A new gel-liquid extraction using a thermosensitive gel was proposed. The thermosensitive gel shows the conformational change of polymer network with temperature, which is known as the phase transition phenomena of gel. The extraction rate and equilibrium of Am(III) in an aqueous solution containing nitrate ion were measured batchwise by using a thermosensitive gel, N-isopropylacrylamide (NIPA) copolymerized with 2-methacryloyloxy- ethylacidphosphate (MR). The effects of the conformational change of polymer network on the extraction rate and equilibrium were discussed. The distribution ratio of Am(III) showed a large value at higher than LCST (low critical solution temperature; 34degC) and was decreased by the phase transition of gel from shrinking to swelling with decreasing temperature. The extraction of Am(III) in the aqueous solution and the release of Am(III) extracted in the gel were repeated stably by the temperature swing operation between 40 and 3degC. The extraction mechanism of Am(III) was described simply as Am 3+ + 3R - OH=(R-O) 3 Am + 3H + (R-OH: MR). The equilibrium constant at the shrinking state (40degC) was more than 3 times of that at swelling state (3degC). The gel-phase diffusivity of Eu(III) used as a substitute of Am(III) was evaluated as the order of 10 -12 m 2 /s at either of 3 or 40degC, which was similar to those for practical extraction chromatographic resins. The temperature-response of gel for the extraction of Eu(III) was very excellent without delay even for the rapid temperature change at 10degC/min. These results suggest that the extraction and release of Am(III) in an aqueous solution can be controlled by the conformational change of polymer network of thermosensitive gel. (author)

Sol/gel analysis of poly (acrylamide-co-metacrylic acid) Hydrogels obtained by gamma radiation for biomedical use

International Nuclear Information System (INIS)

Rapado, M.; Altanes, S.; Prado, S.; Chong, B.; Aguilera, Y.; Saldivar, D.

1999-01-01

Sol-Gel analysis of irradiated polymer was carried out and allowed to estimate important radiation parameters as gelation dose, virtual dose , degradation and crosslinking densities and yield of crosslinking and degradation of copolymer according with a modified Charesby-Pinner equation. The degree of copolymer conversion as a function of the absorbed dose of irradiation is presented. These parameters can be correlated with some physical and chemical properties of polymeric network formation and this way be able to design and prepare gels with the desired structure suitable as a drug delivery system

A systematic review of the precision and accuracy of dose measurements in photon radiotherapy using polymer and Fricke MRI gel dosimetry

International Nuclear Information System (INIS)

MacDougall, N.D.; Pitchford, W.G.; Smith, M.A.

2002-01-01

The purpose of this work is to undertake a critical appraisal of the evidence in the published literature concerning the basic parameters of accuracy and precision associated with the use of Fricke and polymer gels (in conjunction with MR imaging) as radiation dosimeters in photon radiotherapy, condensing and analysing the body of published information (to the end of April 2002). A systematic review was undertaken addressing specific issues of precision and accuracy asking defined questions of the published literature. Accuracy and precision in relation to gel dosimetry were defined. Information was obtained from published, peer-reviewed journals. A defined search strategy utilizing MeSH headings and keywords, with extensive use of cross-referencing, identified 115 references dealing with gel dosimetry. Exclusion criteria were used to select only data from publications which would give unequivocal evidence. For accuracy, results had to be compared with an ionization chamber as gold standard and all gel samples had to be manufactured in the same batch. For precision, in addition to gels being from the same batch, samples must all have been irradiated at the same time and scanned simultaneously (or within a short time frame). Many results were found demonstrating 'dose mapping' examples using gels. However, there were very few publications containing firm evidence of precision and accuracy. There was no evidence which fulfilled our criteria about accuracy or precision using Fricke gels. For polymer gels only one paper was found for accuracy (4% (Low et al 1999 Med. Phys. 26 1542-51)) and precision (1.7% (Baldock et al 1998 Phys. Med. Biol. 43 695-702)); however, both were carried out at only one dose level. If the exclusion criteria were relaxed to include accuracy results comparing gel to a non gold standard dosimeter (e.g. TLD), results give a median accuracy of 10% (range 8-23.5%) for polymer gel (Cosgrove et al 2000 Phys. Med. Biol. 45 1195-210, De Deene et al

Thermostable gel polymer electrolyte based on succinonitrile and ionic liquid for high-performance solid-state supercapacitors

Science.gov (United States)

Pandey, Gaind P.; Liu, Tao; Hancock, Cody; Li, Yonghui; Sun, Xiuzhi Susan; Li, Jun

2016-10-01

A flexible, free-standing, thermostable gel polymer electrolyte based on plastic crystalline succinonitrile (SN) and ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMImBF4) entrapped in copolymer poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) is prepared and optimized for application in solvent-free solid-state supercapacitors. The synthesized gel polymer electrolyte exhibits a high ionic conductivity over a wide temperature range (from ∼5 × 10-4 S cm-1 at -30 °C up to ∼1.5 × 10-2 S cm-1 at 80 °C) with good electrochemical stability window (-2.9 to 2.5 V). Thermal studies confirm that the SN containing gel polymer electrolyte remains stable in the same gel phase over a wide temperature range from -30 to 90 °C. The electric double layer capacitors (EDLCs) have been fabricated using activated carbon as active materials and new gel polymer electrolytes. Electrochemical performance of the EDLCs is assessed through cyclic voltammetry, galvanostatic charge-discharge cycling and impedance spectroscopy. The EDLC cells with the proper SN-containing gel polymer electrolyte has been found to give high specific capacitance 176 F g-1 at 0.18 A g-1 and 138 F g-1 at 8 A g-1. These solid-state EDLC cells show good cycling stability and the capability to retain ∼80% of the initial capacitance after 10,000 cycles.

How a gel polymer electrolyte affects performance of lithium/sulfur batteries

International Nuclear Information System (INIS)

Zhang, Sheng S.; Tran, Dat T.

2013-01-01

Highlights: •Conventional separator is coated with a 50PEO-50SiO 2 (wt.%) composite layer. •Composite coating increases tensile strength and electrolyte wettability. •Coated separator offers an alternative approach for making gel polymer Li/S battery. •Li/S battery takes benefits of gel polymer electrolyte at the expense of capacity. -- Abstract: Gel polymer electrolyte (GPE) and composite gel polymer electrolyte (CGPE) have been widely employed to improve the safety and cycling performance of rechargeable lithium and lithium-ion batteries. In order to determine whether this approach is applicable to lithium/sulfur (Li/S) battery, we examine the effect of CGPE on the cycling and storage performances of Li/S cells by comparing a 50PEO-50SiO 2 (wt.%) composite coated separator (C-separator) with a pristine separator (P-separator). Results show that the composite coating significantly enhances the wettability of liquid electrolyte on the separator and that resulting CGPE can tightly glue the separator and electrode together. In comparison with the P-separator, the C-separator offers Li/S cells similar capacity retention and rate capability; however it greatly affects the specific capacity of sulfur. The analysis on the impedance spectrum of a lithium polysulfide (PS) solution reveal that the reduction of sulfur specific capacity is due to the high viscosity of the CGPE and the strong adsorption of SiO 2 filler to the PS species, which trap PS species in the separator and hence reduce the utilization of sulfur active material. Therefore, the benefits of the GPE and CGPE to the Li/S batteries can be taken only at the expense of sulfur specific capacity

Radiation preparation of drug carriers based polyacrylic acid (PAAc) using poly(vinyl pyrrolidone) (PVP) as a template polymer

Science.gov (United States)

Abd El-Rehim, H. A.; Hegazy, E. A.; Khalil, F. H.; Hamed, N. A.

2007-01-01

The present study deals with the radiation synthesis of stimuli response hydrophilic polymers from polyacrylic acid (PAAc). To maintain the property of PAAc and control the water swellibility for its application as a drug delivery system, radiation polymerization of AAc in the presence of poly(vinyl pyrrolidone) (PVP) as a template polymer was carried out. Characterization of the prepared PAA/PVP inter-polymer complex was investigated by determining gel content, swelling property, hydrogel microstructure and the release rate of caffeine as a model drug. The release rate of caffeine from the PAA/PVP inter-polymer complexes showed pH-dependency, and seemed to be mainly controlled by the dissolution rate of the complex above a p Ka of PAAc. The prepared inter-polymer complex could be used for application as drug carriers.

Changes in molecular structure and properties of irradiated polymers of different compositions - ESR and NMR study

International Nuclear Information System (INIS)

Carswell-Pomerantz, T.; Babanalbandi, A.; Dong, L.; Hill, D.J.T.; Perera, M.C.S.; Pomery, P.J.; Saadat, G.; Whittaker, A.K.

1999-01-01

Investigations of molecular structural changes in polymers during exposure to high energy radiation is the long term interest of the Polymer Materials and Radiation Group at the University of Queensland. Recently, the group had looked at a range of polymers including natural and synthetic rubbers, methacrylates and polyesters. The objective of the work has been to investigate the relationships between polymer structure and sensitivity towards high energy radiation, including gamma radiation. This report will focus on the Electron Spin Resonance (ESR) and Nuclear Magnetic Resonance (NMR) studies of the effects of gamma irradiation on these polymers. Other methods such as Gas Chromatography (GC), Gel Permeation Chromatography (GPC), Fourier Transformed Infra Red (FTIR), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Dynamic Mechanical Analysis (DMA) have also been used as these methods combine with ESR and NMR, to provide a more complete picture of the mechanism of the structural changes. (author)

Ionizing radiation effect on physico-mechanical characteristics of thermoplastic polymer materials

International Nuclear Information System (INIS)

Stankevich, V.M.; Pleskachevsky, Yu.M.; Smirnov, V.V.

2001-01-01

Investigation results in the field of ionizing radiation effect on structure and physico-mechanical properties of novel polymer materials are presented. The materials under study are various grades of PETP, PA-6 and polyethylene concentrate of technical carbon (PECC) commercially produced and extensively used in Belarus and abroad. It has been proved using EPR, thermomechanical and gel analyses that a combined effect of ionizing radiation within 0 to 10 MGy of absorbed dose range under different concentrations of mineral fillers (TiO 2 , kaolin, carbon black, graphite) and intensive cross-linking processes in amorphous phase are able to considerably improve strength characteristics of the studied polymers and their compositions. Most informative parameter was found to be breaking strength at rapture (σ r ) which enables to estimate the character of ionizing effect on the targets. At 0.01-0.05 MGy absorbed dose the highest σ r was shown as compared to initial PETP by the following materials: PN grade - 9 times, D - two and a half. When absorbed dose of PETP reached 0.2 MGy, σ r of PN surpassed the initial material 7.8 times, that of D - by 30% and E - by 1,5%. This is the evidence of elevated resistance of named materials to ionizing radiation in contrast to non-filled PETP 215. Growth of σ r in PA-6 has been noticed at absorbed dose above 2 MGy in response to maximum gel-formation values. Abrupt reduction of the studied parameters of PP upon irradiation is attributed to its destruction. Domination of cross-linking processes has been observed in PEVP and PECC which reduces macromolecular mobility and elasticity of the material as a whole but promotes polymer strengthening. Drop of PEVP impact strength can be related to its embrittlement. Presence of the filler (carbon black) in PECC at the initial stage of exposure resulted in improvement of studied parameters. Their further impairment is the result of limited mobility of macromolecules owing to cross-linking in

Radiation-induced polymerization and radiation effect on polymers

International Nuclear Information System (INIS)

Seguchi, Tadao

1977-12-01

The processes of radiation-induced polymerization of monomers and also radiation effects on polymers have been studied by instrumental analyses of electron spin resonance (ESR), nuclear magnetic resonance (NMR) and electron microscopy. In radiation-induced polymerization, graft-copolymerization and absorbed state polymerization were taken up. For graft-copolymerization, monomers such as methylmethacrylate and butadiene were made to react with irradiated polyethylene, and behaviors of the initiating radicals and propagating radicals were followed under the reaction by ESR. For absorbed state polymerization, acrylonitrile/zeolite and methylmethacrylate/zeolite were chosen. Absorbed monomers were irradiated at 77 0 K and polymerized at room temperature. Active species and the concentrations were measured by ESR and the yields of polymer were observed by NMR. In radiation effect on polymers, polyvinylfluoride, polyvinylidenfluoride and polytetrafluoroethylene were taken up. Active species trapped in the polymer matrixes were identified and decay and reactivity of the species were also studied. On the basis of information from the electron microscopy and x-ray analysis, radiation effects on these polymers are described. In polytetrafluoroethylene produced by radiation polymerization, the relation between morphology and polymerization conditions and also the process of crystallization during polymerization were studied. (auth.)

Novel Stable Gel Polymer Electrolyte: Toward a High Safety and Long Life Li-Air Battery.

Science.gov (United States)

Yi, Jin; Liu, Xizheng; Guo, Shaohua; Zhu, Kai; Xue, Hailong; Zhou, Haoshen

2015-10-28

Nonaqueous Li-air battery, as a promising electrochemical energy storage device, has attracted substantial interest, while the safety issues derived from the intrinsic instability of organic liquid electrolytes may become a possible bottleneck for the future application of Li-air battery. Herein, through elaborate design, a novel stable composite gel polymer electrolyte is first proposed and explored for Li-air battery. By use of the composite gel polymer electrolyte, the Li-air polymer batteries composed of a lithium foil anode and Super P cathode are assembled and operated in ambient air and their cycling performance is evaluated. The batteries exhibit enhanced cycling stability and safety, where 100 cycles are achieved in ambient air at room temperature. The feasibility study demonstrates that the gel polymer electrolyte-based polymer Li-air battery is highly advantageous and could be used as a useful alternative strategy for the development of Li-air battery upon further application.

Adaptive mean filtering for noise reduction in CT polymer gel dosimetry

International Nuclear Information System (INIS)

Hilts, Michelle; Jirasek, Andrew

2008-01-01

X-ray computed tomography (CT) as a method of extracting 3D dose information from irradiated polymer gel dosimeters is showing potential as a practical means to implement gel dosimetry in a radiation therapy clinic. However, the response of CT contrast to dose is weak and noise reduction is critical in order to achieve adequate dose resolutions with this method. Phantom design and CT imaging technique have both been shown to decrease image noise. In addition, image postprocessing using noise reduction filtering techniques have been proposed. This work evaluates in detail the use of the adaptive mean filter for reducing noise in CT gel dosimetry. Filter performance is systematically tested using both synthetic patterns mimicking a range of clinical dose distribution features as well as actual clinical dose distributions. Both low and high signal-to-noise ratio (SNR) situations are examined. For all cases, the effects of filter kernel size and the number of iterations are investigated. Results indicate that adaptive mean filtering is a highly effective tool for noise reduction CT gel dosimetry. The optimum filtering strategy depends on characteristics of the dose distributions and image noise level. For low noise images (SNR ∼20), the filtered results are excellent and use of adaptive mean filtering is recommended as a standard processing tool. For high noise images (SNR ∼5) adaptive mean filtering can also produce excellent results, but filtering must be approached with more caution as spatial and dose distortions of the original dose distribution can occur

Synergetic effect of green tea on polymer gel dosimeter and determination of optimal wavelength to choose light source for optical computed tomography

Directory of Open Access Journals (Sweden)

Sathiya Raj

2016-03-01

Full Text Available Purpose: The ultimate aim of this study is to observe the effect of Green tea as a co-antioxidant in PAGAT gel dosimeter and evaluate the appropriate light source for scanning the PAGAT and NIPAM polymer gel.Methods: Both PAGAT (Poly Acrylamide Gelatin Tetrakis hydroxyl phosphonium chloride and NIPAM (N-Isopropyl acrylamide gel were prepared in normoxic condition. The green tea extract (GTE was prepared and tested only on PAGAT. Co-60 teletherapy machine has been used for irradiation purpose, and the gel samples were scanned using UV-Visible spectrophotometer. Water equivalency of the gel has been tested in terms of their electron density, effective atomic number and Ratio of oxygen and hydrogen (O/H. We have used NIST XCOM database to test the water equivalency.Results: In this study we found that the GTE added to the gel do not respond to the given doses. By adding sugar we can enhance the sensitivity of the gel. Further investigations are required to use Green tea as a co antioxidant concentration of THPC (Tetrakis hydroxymethyl phosphonium chloride. The optimal wavelength with different region for scanning the PAGAT is 450 to 480 nm (Blue region, for NIPAM it is 540 nm and 570 nm (Green and yellow region. The PAGAT and NIPAM showed better sensitivity at 510 nm. Both gels have their effective atomic number closer to water (NIPAM-7.2, PAGAT-7.379.Conclusion: As per our results, we concluded that GTE alone is not an effective co-antioxidant for polymer gels. When the GTE is combined with sugar and THPC, it protects the gel from pre-polymerization. This study strongly suggests that the blue light is an optimal source for scanning the PAGAT and green to yellow light for NIPAM gel. Though both gels were considered as water equivalent, the PAGAT is equivalent to water and the temporal stability of this gel is higher than NIPAM.

The spatial resolution in dosimetry with normoxic polymer-gels investigated with the dose modulation transfer approach

International Nuclear Information System (INIS)

Bayreder, Christian; Schoen, Robert; Wieland, M.; Georg, Dietmar; Moser, Ewald; Berg, Andreas

2008-01-01

The verification of dose distributions with high dose gradients as appearing in brachytherapy or stereotactic radiotherapy for example, calls for dosimetric methods with sufficiently high spatial resolution. Polymer gels in combination with a MR or optical scanner as a readout device have the potential of performing the verification of a three-dimensional dose distribution within a single measurement. The purpose of this work is to investigate the spatial resolution achievable in MR-based polymer gel dosimetry. The authors show that dosimetry on a very small spatial scale (voxel size: 94x94x1000 μm 3 ) can be performed with normoxic polymer gels using parameter selective T2 imaging. In order to prove the spatial resolution obtained we are relying on the dose-modulation transfer function (DMTF) concept based on very fine dose modulations at half periods of 200 μm. Very fine periodic dose modulations of a 60 Co photon field were achieved by means of an absorption grid made of tungsten-carbide, specifically designed for quality control. The dose modulation in the polymer gel is compared with that of film dosimetry in one plane via the DMTF concept for general access to the spatial resolution of a dose imaging system. Additionally Monte Carlo simulations were performed and used for the calculation of the DMTF of both, the polymer gel and film dosimetry. The results obtained by film dosimetry agree well with those of Monte Carlo simulations, whereas polymer gel dosimetry overestimates the amplitude value of the fine dose modulations. The authors discuss possible reasons. The in-plane resolution achieved in this work competes with the spatial resolution of standard clinical film-scanner systems

Small field dose delivery evaluations using cone beam optical computed tomography-based polymer gel dosimetry

Directory of Open Access Journals (Sweden)

Timothy Olding

2011-01-01

Full Text Available This paper explores the combination of cone beam optical computed tomography with an N-isopropylacrylamide (NIPAM-based polymer gel dosimeter for three-dimensional dose imaging of small field deliveries. Initial investigations indicate that cone beam optical imaging of polymer gels is complicated by scattered stray light perturbation. This can lead to significant dosimetry failures in comparison to dose readout by magnetic resonance imaging (MRI. For example, only 60% of the voxels from an optical CT dose readout of a 1 l dosimeter passed a two-dimensional Low′s gamma test (at a 3%, 3 mm criteria, relative to a treatment plan for a well-characterized pencil beam delivery. When the same dosimeter was probed by MRI, a 93% pass rate was observed. The optical dose measurement was improved after modifications to the dosimeter preparation, matching its performance with the imaging capabilities of the scanner. With the new dosimeter preparation, 99.7% of the optical CT voxels passed a Low′s gamma test at the 3%, 3 mm criteria and 92.7% at a 2%, 2 mm criteria. The fitted interjar dose responses of a small sample set of modified dosimeters prepared (a from the same gel batch and (b from different gel batches prepared on the same day were found to be in agreement to within 3.6% and 3.8%, respectively, over the full dose range. Without drawing any statistical conclusions, this experiment gives a preliminary indication that intrabatch or interbatch NIPAM dosimeters prepared on the same day should be suitable for dose sensitivity calibration.

The role of radiation in polymer chemistry

International Nuclear Information System (INIS)

Du Plessis, T.A.

1977-10-01

The very important role which polymer chemistry plays in radiation technology is discussed. The present status of radiation processing and the radiation sources that are used by industry are described. The process by which ionising radiation interacts with vinyl monomers and polymers are treated briefly, and the kinetics and mechanisms of the industrially important radiation processes in the polymer field is discussed. Finally, some of the most important industrial radiation processes related to the field of polymers are pointed out [af

Electron beam dosimetry in heterogeneous phantoms using a MAGIC normoxic polymer gel

International Nuclear Information System (INIS)

Ghahraman Asl, R.; Nedaie, H.; Bolouri, B.; Arbabi, A.

2010-01-01

Nowadays radiosensitive polymer gels are used as a reliable dosimetry tool for verification of 3D dose distributions. Special characteristics of these dosimeters have made them useful for verification of complex dose distributions in clinical situations. The aim of this work was to evaluate the capability of a normoxic polymer gel to determine electron dose distributions in different slab phantoms in presence of small heterogeneities. Materials and Methods: Different cylindrical phantoms consisting gel were used under slab phantoms during each irradiation. MR images of irradiated gel phantoms were obtained to determine their R2 relaxation maps. 1D and 2D lateral dose profiles were acquired at depths of 1 cm for an 8 MeV beam and 1 and 4 cm for the 15 MeV energy, and then compared with the lateral dose profiles measured using a diode detector. In addition, 3D dose distributions around these heterogeneities for the same energies and depths were measured using a gel dosimeter. Results: Dose resolution for MR gel images at the range of 0-10 Gy was less than 1.55 Gy. Mean dose difference and distance to agreement for dose profiles were 2.6% and 2.2 mm, respectively. The results of the MAGIC-type polymer gel for bone heterogeneity at 8 MeV showed a reduction in dose of approximately 50%, and 30% and 10% at depths 1 and 4 cm at 15 MeV. However, for air heterogeneity increases in dose of approximately 50% at depth 1 cm under the heterogeneity at 8 MeV and 20% and 45% respectively at 15 MeV were observed. Discussion and Conclusion: Generally, electron beam distributions are significantly altered in the presence of tissue inhomogeneities such as bone and air cavities, this being related to mass stopping and mass scattering powers of heterogeneous materials. At the same time, hot and cold scatter lobes under heterogeneity regions due to scatter edge effects were also seen. However, these effects (increased dose, reduced dose, hot and cold spots) at deeper depths, are

Process for crosslinking methylene-containing aromatic polymers with ionizing radiation

Science.gov (United States)

Bell, Vernon L. (Inventor); Havens, Stephen J. (Inventor)

1990-01-01

A process for crosslinking aromatic polymers containing radiation-sensitive methylene groups (-CH2-) by exposing the polymers to ionizing radiation thereby causing crosslinking of the polymers through the methylene groups is described. Crosslinked polymers are resistant to most organic solvents such as acetone, alcohols, hydrocarbons, methylene, chloride, chloroform, and other halogenated hydrocarbons, to common fuels and to hydraulic fluids in contrast to readily soluble uncrosslinked polymers. In addition, the degree of crosslinking of the polymers depends upon the percentage of the connecting groups which are methylene which ranges from 5 to 50 pct and preferably from 25 to 50 pct of the connecting groups, and is also controlled by the level of irradiation which ranges from 25 to 1000 Mrads and preferably from 25 to 250 Mrads. The temperature of the reaction conditions ranges from 25 to 200 C and preferably at or slightly above the glass transition temperature of the polymer. The crosslinked polymers are generally more resistant to degradation at elevated temperatures such as greater than 150 C, have a reduced tendency to creep under load, and show no significant embrittlement of parts fabricated from the polymers.

Heterogeneity phantoms for visualization of 3D dose distributions by MRI-based polymer gel dosimetry

International Nuclear Information System (INIS)

Watanabe, Yoichi; Mooij, Rob; Mark Perera, G.; Maryanski, Marek J.

2004-01-01

Heterogeneity corrections in dose calculations are necessary for radiation therapy treatment plans. Dosimetric measurements of the heterogeneity effects are hampered if the detectors are large and their radiological characteristics are not equivalent to water. Gel dosimetry can solve these problems. Furthermore, it provides three-dimensional (3D) dose distributions. We used a cylindrical phantom filled with BANG-3 registered polymer gel to measure 3D dose distributions in heterogeneous media. The phantom has a cavity, in which water-equivalent or bone-like solid blocks can be inserted. The irradiated phantom was scanned with an magnetic resonance imaging (MRI) scanner. Dose distributions were obtained by calibrating the polymer gel for a relationship between the absorbed dose and the spin-spin relaxation rate of the magnetic resistance (MR) signal. To study dose distributions we had to analyze MR imaging artifacts. This was done in three ways: comparison of a measured dose distribution in a simulated homogeneous phantom with a reference dose distribution, comparison of a sagittally scanned image with a sagittal image reconstructed from axially scanned data, and coregistration of MR and computed-tomography images. We found that the MRI artifacts cause a geometrical distortion of less than 2 mm and less than 10% change in the dose around solid inserts. With these limitations in mind we could make some qualitative measurements. Particularly we observed clear differences between the measured dose distributions around an air-gap and around bone-like material for a 6 MV photon beam. In conclusion, the gel dosimetry has the potential to qualitatively characterize the dose distributions near heterogeneities in 3D

Fast, three-dimensional, MR Imaging for polymer gel dosimetric applications involving high dose and steep dose gradients

International Nuclear Information System (INIS)

Sandilos, Panagiotis; Baras, Panagiotis; Georgiou, Evangelos; Dardoufas, Konstantinos; Karaiskos, Pantelis; Papagiannis, Panagiotis; Paschalis, Theodoros; Tatsis, Elias; Torrens, Michael; Vlahos, Lampros

2006-01-01

Polymer gels constitute water equivalent integrating detectors, which, combined with magnetic resonance imaging (MRI), can provide accurate three dimensional (3D) dose distributions in contemporary radiotherapy applications where the small field dimensions and steep dose gradients induce limitations to conventional dosimeters. One of the main obstacles for adapting the method for routine use in the clinical setting is the cost effectiveness of the MRI readout method. Currently, optimized Carr-Purcell-Meiboom-Gill (CPMG) multiple spin echo imaging pulse sequences are commonly used which however result in long imaging times. This work evaluates the efficiency of 3D, dual-echo, k-space segmented turbo spin echo (TSE) scanning sequences for accurate dosimetry with sub-millimetre spatial resolution in strenuous radiation therapy applications. PABIG polymer gel dosimeters were irradiated with an 192 Ir High Dose Rate brachytherapy source, the 4 mm and 8 mm collimator helmets of a gamma knife unit and a custom made x-knife collimator of 1 cm diameter. Profile and dose distribution measurements using TSE are benchmarked against corresponding findings obtained by the commonly used, but time consuming, CPMG sequence as well as treatment planning calculations, Monte Carlo (MC) simulations and film measurements. The implementation of a high Turbo factor was found to provide comparable accuracy, allowing a 64-fold MRI scan acceleration compared to conventional multi-echo sequences. The availability of TSE sequences in typical MRI installations greatly facilitates the introduction of polymer gel dosimetry in the clinical environment as a practicable tool for the determination of full 3D dose distributions in contemporary radiotherapy applications

Fast, three-dimensional, MR Imaging for polymer gel dosimetric applications involving high dose and steep dose gradients

Energy Technology Data Exchange (ETDEWEB)

Sandilos, Panagiotis [Department of Radiology, Medical School, University of Athens, Areteion Hospital, 76 Vas. Sofias Ave., 115 28 Athens (Greece); Baras, Panagiotis [Philips Hellas Medical Systems, 44 Kifissias Ave., Maroussi 151 25, Athens (Greece); Georgiou, Evangelos [Medical Physics Department, University of Athens, 75 Mikras Asias, 115 27 Athens (Greece); Dardoufas, Konstantinos [Department of Radiology, Medical School, University of Athens, Areteion Hospital, 76 Vas. Sofias Ave., 115 28 Athens (Greece): Hygeia Hospital, Kiffisias Avenue and 4 Erythrou Stavrou, Marousi, 151 23 Athens (Greece); Karaiskos, Pantelis [Medical Physics Department, University of Athens, 75 Mikras Asias, 115 27 Athens (Greece): Hygeia Hospital, Kiffisias Avenue and 4 Erythrou Stavrou, Marousi, 151 23 Athens (Greece)]. E-mail: p.karaiskos@hygeia.gr; Papagiannis, Panagiotis [Physics Department, Nuclear and Particle Physics Section, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece); Paschalis, Theodoros [Department of Radiology, Medical School, University of Athens, Areteion Hospital, 76 Vas. Sofias Ave., 115 28 Athens (Greece); Tatsis, Elias [Department of Radiology, Medical School, University of Athens, Areteion Hospital, 76 Vas. Sofias Ave., 115 28 Athens (Greece); Torrens, Michael [Hygeia Hospital, Kiffisias Avenue and 4 Erythrou Stavrou, Marousi, 151 23 Athens (Greece); Vlahos, Lampros [Department of Radiology, Medical School, University of Athens, Areteion Hospital, 76 Vas. Sofias Ave., 115 28 Athens (Greece)

2006-12-20

Polymer gels constitute water equivalent integrating detectors, which, combined with magnetic resonance imaging (MRI), can provide accurate three dimensional (3D) dose distributions in contemporary radiotherapy applications where the small field dimensions and steep dose gradients induce limitations to conventional dosimeters. One of the main obstacles for adapting the method for routine use in the clinical setting is the cost effectiveness of the MRI readout method. Currently, optimized Carr-Purcell-Meiboom-Gill (CPMG) multiple spin echo imaging pulse sequences are commonly used which however result in long imaging times. This work evaluates the efficiency of 3D, dual-echo, k-space segmented turbo spin echo (TSE) scanning sequences for accurate dosimetry with sub-millimetre spatial resolution in strenuous radiation therapy applications. PABIG polymer gel dosimeters were irradiated with an {sup 192}Ir High Dose Rate brachytherapy source, the 4 mm and 8 mm collimator helmets of a gamma knife unit and a custom made x-knife collimator of 1 cm diameter. Profile and dose distribution measurements using TSE are benchmarked against corresponding findings obtained by the commonly used, but time consuming, CPMG sequence as well as treatment planning calculations, Monte Carlo (MC) simulations and film measurements. The implementation of a high Turbo factor was found to provide comparable accuracy, allowing a 64-fold MRI scan acceleration compared to conventional multi-echo sequences. The availability of TSE sequences in typical MRI installations greatly facilitates the introduction of polymer gel dosimetry in the clinical environment as a practicable tool for the determination of full 3D dose distributions in contemporary radiotherapy applications.

Development and dosimetric evaluation of radiochromic PCDA vesicle gel dosimeters

International Nuclear Information System (INIS)

Sun, P.; Fu, Y.C.; Hu, J.; Hao, N.; Huang, W.; Jiang, B.

2016-01-01

The gel dosimeter has the unique capacity in recording radiation dose distribution in three dimensions (3D), which has the specific advantages in dosimetry measurements where steep dose gradients exist, such as in intensity-modulated radiation therapy (IMRT), brachytherapy and so on. Some 3D dosimeters, such as Fricke gel dosimeters, polymer gel dosimeters, the PRESAGE plastic dosimeters and micelle gel dosimeters have appeared recently. However, there are several disadvantages of these 3D dosimeters limit their application in radiotherapy dose verification. In this study, a novel radiochromic gel dosimeter for 3D dose verification of radiotherapy was developed by dispersing nanovesicles self-assembled by 10,12-pentacosadiynoic acid (PCDA) into the tissue equivalence gel matrix. The characteristics of radiochromic PCDA vesicle gel dosimeters were evaluated. The results indicate that these radiochromic gel dosimeters have good linear dose response to X-ray irradiation in the dose range of 2–100 Gy. In addition, the radiochromic gel dosimeters breakthrough the limitations of the existing gel dosimeters such as diffusion effect, post-radiation effect, and poor forming ability. The response of the gel dosimeter does not show any dose rate dependence, energy dependence and temperature effect, and there was no obvious difference in the gel response between single and cumulative dose of fractional irradiation. Hence, the radiochromic PCDA vesicle gel dosimeters developed in this study could be generally applied to 3D dose verification in radiotherapy. - Highlights: • A novel radiochromic gel dosimeter was developed by dispersing PCDA nanovesicles into the tissue equivalence gel matrix. • This nanovesicle overcomes the dose image blurring caused by the diffusion of monomer molecules. • This nanovesicle limits the polymer chain growth, so as to reduce the post-radiation effect. • The gel matrixes possess excellent tissue equivalence and elastic strength, which

Recent developments in polymer gel dosimetry

International Nuclear Information System (INIS)

John Schreiner, L.; Olding, Tim; Holmes, Oliver; McAuley, Kim

2008-01-01

Modern radiation therapy particularly with intensity modulation techniques (IMRT) offers the potential to improve patient outcomes by better limiting high doses to the tumour alone. In this presentation we report our progress in developing gel dosimetry with new less toxic dosimeters using a fast commercial optical computed tomography (OCT) scanner. We will demonstrate that these adjustments in the approach to gel dosimetry help facilitate its introduction into clinical use. We will review practical advances in system quality assurance and scatter correction to improve optical CT quantification, and show an example of a clinical implementation of an IGRT treatment validation

Ionic Liquid-Doped Gel Polymer Electrolyte for Flexible Lithium-Ion Polymer Batteries

Science.gov (United States)

Zhang, Ruisi; Chen, Yuanfen; Montazami, Reza

2015-01-01

Application of gel polymer electrolytes (GPE) in lithium-ion polymer batteries can address many shortcomings associated with liquid electrolyte lithium-ion batteries. Due to their physical structure, GPEs exhibit lower ion conductivity compared to their liquid counterparts. In this work, we have investigated and report improved ion conductivity in GPEs doped with ionic liquid. Samples containing ionic liquid at a variety of volume percentages (vol %) were characterized for their electrochemical and ionic properties. It is concluded that excess ionic liquid can damage internal structure of the batteries and result in unwanted electrochemical reactions; however, samples containing 40–50 vol % ionic liquid exhibit superior ionic properties and lower internal resistance compared to those containing less or more ionic liquids.

Surface-selective laser sintering of thermolabile polymer particles using water as heating sensitizer

Energy Technology Data Exchange (ETDEWEB)

Antonov, E N; Krotova, L I; Minaev, N V; Minaeva, S A; Mironov, A V; Popov, V K [Institute on Laser and Information Technologies of the Russian Academy of Sciencies, Troitsk, Moscow (Russian Federation); Bagratashvili, V N [Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

2015-11-30

We report the implementation of a novel scheme for surface-selective laser sintering (SSLS) of polymer particles, based on using water as a sensitizer of laser heating and sintering of particles as well as laser radiation at a wavelength of 1.94 μm, corresponding to the strong absorption band of water. A method of sintering powders of poly(lactide-co-glycolide), a hydrophobic bioresorbable polymer, after modifying its surface with an aqueous solution of hyaluronic acid is developed. The sintering thresholds for wetted polymer are by 3 – 4 times lower than those for sintering in air. The presence of water restricts the temperature of the heated polymer, preventing its thermal destruction. Polymer matrices with a developed porous structure are obtained. The proposed SSLS method can be applied to produce bioresorbable polymer matrices for tissue engineering. (interaction of laser radiation with matter. laser plasma)

Three-dimensional visualization and measurement of conformal dose distributions using magnetic resonance imaging of bang polymer gel dosimeters

International Nuclear Information System (INIS)

Ibbott, Geoffrey S.; Maryanski, Marek J.; Eastman, Peter; Holcomb, Stephen D.; Yashan, Zhang; Avison, Robin G.; Sanders, Michael; Gore, John C.

1997-01-01

Purpose/Objective: The measurement of complex dose distributions (those created by irradiation through multiple beams, multiple sources, or multiple source dwell positions) requires a dosimeter that can integrate the dose during a complete treatment. Integrating dosimeter devices generally are capable of measuring only dose at a point (ion chamber, diode, TLD) or in a plane (film). With increasing use of conformal dose distributions requiring shaped, non coplanar beams, there will be an increased requirement for a dosimeter that can record and display a 3D dose distribution. The use of a 3D dosimeter will be required to confirm the accuracy of treatment plans produced by the current generation of 3D treatment-planning computers. Methods and Materials: The use of a Fricke-infused gel and magnetic resonance imaging (MRI) to demonstrate the localization of stereotactic beams has been demonstrated (11). The recently developed BANG polymer gel dosimetry system (MGS Research, Inc., Guilford, CT), based on radiation-induced chain polymerization of acrylic monomers dispersed in a tissue-equivalent gel, surpasses the Fricke-gel method by providing accurate, quantitative dose distribution data that do not deteriorate with time (6, 9). The improved BANG2 formulation contains 3% N,N'-methylene-bis acrylamide, 3% acrylic acid, 1% sodium hydroxide, 5% gelatin, and 88% water, where all percentages are by weight. The gel was poured into volumetric flasks, of dimensions comparable to a human head. The gels were irradiated with complex beam arrangements, similar to those used for conformal radiation therapy. Images of the gels were acquired using a Siemens 1.5T imager and a Hahn spin-echo pulse sequence (90 deg. -τ-180 deg. -τ-acquire, for different values of τ). The images were transferred via network to a Macintosh computer for which a data analysis and display program was written. The program calculates R2 maps on the basis of multiple TE images, using a monoexponential

Temperature-sensitive microemulsion gel: an effective topical delivery system for simultaneous delivery of vitamins C and E.

Science.gov (United States)

Rozman, Branka; Zvonar, Alenka; Falson, Francoise; Gasperlin, Mirjana

2009-01-01

Microemulsions (ME)--nanostructured systems composed of water, oil, and surfactants--have frequently been used in attempts to increase cutaneous drug delivery. The primary objective addressed in this work has been the development of temperature-sensitive microemulsion gel (called gel-like ME), as an effective and safe delivery system suitable for simultaneous topical application of a hydrophilic vitamin C and a lipophilic vitamin E. By changing water content of liquid o/w ME (o/w ME), a gel-like ME with temperature-sensitive rheological properties was formed. The temperature-driven changes in its microstructure were confirmed by rotational rheometry, viscosity measurements, and droplet size determination. The release studies have shown that the vitamins' release at skin temperature from gel-like ME were comparable to those from o/w ME and were much faster and more complete than from o/w ME conventionally thickened with polymer (o/w ME carbomer). According to effectiveness in skin delivery of both vitamins, o/w ME was found the most appropriate, followed by gel-like ME and by o/w ME carbomer, indicating that no simple correlation between vitamins release and skin absorption could be found. The cytotoxicity studies revealed good cell viability after exposure to ME and confirmed all tested microemulsions as nonirritant.

Characterization of long-term dose stability of N-isopropylacrylamide polymer gel dosimetry

International Nuclear Information System (INIS)

Chang, Y.J.; Central Taiwan University of Science and Technology, Taichung City, Taiwan, ROC; Chen, C.H.; Hsieh, B.T.

2014-01-01

In this study, the detailed characteristics, including spatial uniformity, dose distributions, inter-batch variability, reproducibility, and long-term temporal stability, of N-isopropylacrylamide (NIPAM) polymer gel dosimeter were investigated. A commercial 10x fast optical computed tomography scanner (OCTOPUS TM -10×, MGS Research, Inc., Madison, CT, USA) was used to measure NIPAM polymer gel dosimeter. A cylindrical NIPAM gel phantom that measured 10 cm × 10 cm was irradiated via a single-field treatment plan with a field size of 4 cm × 4 cm. The maximum standard deviation of spatial uniformity for NIPAM gel was less than 0.29 %. The average standard deviation among the three batches of gel dosimeters was less than 1 %. The gamma pass rate could reach as high as 96.76 % when a 3 % dose difference and a 3 mm dose-to-agreement criteria were used. The long-term measurement of irradiated NIPAM gel dosimeter indicated that the dose maps attained a gradually stable value 15 h post-irradiation and remained stable until 72 h post-irradiation. The gamma pass rate could achieve a maximum value between 24 and 72 h post-irradiation. The edge enhancement effect that occurred around the irradiated region was observed 72 h post-irradiation. Thus, the results from this study suggest that NIPAM gel dosimeter should be measured approximately 24 h post-irradiation to reduce the occurrence of the edge enhancement effect. (author)

Study of the influence of gold particles on the absorbed dose in soft tissue using polymer gel dosimetry

International Nuclear Information System (INIS)

Afonso, Luciana Caminha

2011-01-01

The presence of high-Z material adjacent to soft tissue, when submitted to irradiation, enhances locally the absorbed dose in these soft tissues. Such effect occurs due to the outscattering of photoelectrons from the high-Z material. Polymer gel dosimeters have been used to investigate this effect. Analytic calculations to estimate the dose enhancement and Monte Carlo simulations have been performed. Samples containing polymer gel (PG) with 0.005 gAu/gPG and pure polymer gel have been irradiated using an X-rays beam produced by 150 kV, filtered with 4 mm Al and 5 mm Cu, which resulted in an approximately 20% higher absorbed dose in the samples with gold in comparison to those with pure polymer gel. The analytic calculations and the Monte Carlo simulation resulted in a dose enhancement factor of approximately 30%. (author)

Radiation stress relieving of polymer articles

International Nuclear Information System (INIS)

Frisch, D.C.; Weber, W.

1982-01-01

A method of rapidly relieving stress in an extruded or molded polymer article is disclosed. The method can be used in the preparation of printed circuit boards. An article comprised of the polymer is exposed to electromagnetic radiation, for a time period sufficient to absorb enough energy to stress relieve the polymer against stress cracking therein. Exposure occurs at one or more ranges of frequencies which are capable of being absorbed by the polymer and which are effective for stress relieving without or substantially without causing heat induced softening or flowing of the polymer. The electromagnetic radiation is selected from the ranges of infrared, microwave or ultraviolet radiation

Basic investigations on the performance of a normoxic polymer gel with tetrakis-hydroxy-methyl-phosphonium chloride as an oxygen scavenger: Reproducibility, accuracy, stability, and dose rate dependence

International Nuclear Information System (INIS)

Bayreder, Christian; Georg, Dietmar; Moser, Ewald; Berg, Andreas

2006-01-01

methacrylic acid and gelatin. Polymer gels containing THPC offer high sensitivity to dose but their dose response also strongly depends on dose rate in the medium and high dose region

Use of Magic polymer gels for dosimetry of unsealed source of yttrium 90

International Nuclear Information System (INIS)

Meynard, K.; Bordage, M.C.; Cassol, E.; Courbon, F.; Ravel, P.

2007-01-01

Polymer gels are relative chemical dosimeters. They allow to access to three-dimensional dose distribution. The aim of this study has been to investigate the preparation and the use of a polymer gel with a tissue equivalent density known as MAGIC gel from magnetic resonance imaging and x-ray computed tomography for non-sealed source dosimetry. This kind of gel is 'normoxic' because it can be manufactured and used in normal room atmosphere. In the first part of this study, its accuracy and sensibility were studied using external beam irradiation by photons. Spin-spin relaxation rate (R 2 ) and Computed Tomography (CT) number had been used to record gel responses. Using the same manufacture process. radiolabelled gels composed of 95% MAGIC gel and 5% of 90 Y termed 90 Y-MAGIC 95 with varying activity ranged from 0 to 30 MBq were made. In case of photon external beam irradiation, a linear response is observed whatever the calibration method and the imaging system used (the correlation coefficient r 2 > 0.98 in all cases). 90 Y-MAGIC 95 radiolabelled gel responses were recorded after 28. 76 and 124 h. The R 2 /dose curves are not linear: three phases can be described. the first being linear with a slow slope (0.14 s -1 Gy -1 instead of 0.41 s -1 Gy -1 for external beam irradiation of the same gel batch). This study shows safety of radiolabelled MAGIC gels manufacturing process and their large dosimetric feasibility. 90 Y-MAGIC 95 gel response appears to be reproducible and related to the absorbed dose, thus this gel is a promising tool for non-sealed source dosimetry. (authors)

Surface structure of polymer Gels and emerging functions

CERN Document Server

Kobiki, Y

1999-01-01

We report the surface structure of polymer gels on a submicrometer scale during the volume phase transition. Sponge-like domains with a mesoscopic scale were directly observed in water by using at atomic force microscope (AFM). The surface structure characterized by the domains is discussed in terms of the root-mean-square roughness and the auto-correlation function, which were calculated from the AFM images. In order to demonstrate the role of surface structure in determining the macroscopic properties of film-like poly (N-isopropylacrylamide: NIPA) gels. It was found that the temperature dependence, as well as the absolute values of the static contact angle, were strongly dependent on the bulk network inhomogeneities. The relation between the mesoscopic structure and the macroscopic properties is qualitatively discussed in terms of not only the changes in the chemical, but also in the physical, surface properties of the NIPA gels in response to a temperature change.

Ionic Liquid-Doped Gel Polymer Electrolyte for Flexible Lithium-Ion Polymer Batteries

Directory of Open Access Journals (Sweden)

Ruisi Zhang

2015-05-01

Full Text Available Application of gel polymer electrolytes (GPE in lithium-ion polymer batteries can address many shortcomings associated with liquid electrolyte lithium-ion batteries. Due to their physical structure, GPEs exhibit lower ion conductivity compared to their liquid counterparts. In this work, we have investigated and report improved ion conductivity in GPEs doped with ionic liquid. Samples containing ionic liquid at a variety of volume percentages (vol % were characterized for their electrochemical and ionic properties. It is concluded that excess ionic liquid can damage internal structure of the batteries and result in unwanted electrochemical reactions; however, samples containing 40–50 vol % ionic liquid exhibit superior ionic properties and lower internal resistance compared to those containing less or more ionic liquids.

Radiation-induced DNA breaks detected by immuno labelling of poly(ADP-ribose) in CHO cells. Standardization by pulsed-field gel electrophoresis

International Nuclear Information System (INIS)

Varlet, P.; Bidon, N.; Noel, G.; Averbeck, D.; Salamero, J.; DeMurcia, G.

1998-01-01

The poly (ADP-ribose) polymerase is an ubiquitous nuclear protein capable of binding specifically to DNA strand breaks. It synthesizes ADP-ribose polymers proportionally to DNA breaks. The actual method of reference to determine DNA double strand breaks is pulsed-field gel electrophoresis, but this requires many cells. It thus appeared of interest to use poly (ADP-ribos)ylation to follow and estimate γ-ray-induced DNA fragmentation at the level of isolated cells after γ-irradiation in chinese hamster ovary cells (CHO-K1). The results obtained by the immuno-labelling technique of ADP-ribose polymers were compared to those obtained by pulsed-field gel electrophoresis. They show that poly (ADP-ribos)ylation reflects the occurrence of radiation-induced DNA strand breaks. A clear relationship exists between the amount of ADP-ribose polymers detected and DNA double strand breaks after γ-irradiation. (authors)

Incorporating multislice imaging into x-ray CT polymer gel dosimetry

Energy Technology Data Exchange (ETDEWEB)

Johnston, H., E-mail: holly.johnston@utsw.edu [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8W 2Y2 (Canada); Hilts, M. [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada and Medical Physics, BC Cancer Agency, Vancouver Island Centre, Victoria, British Columbia V8R 6V5 (Canada); Jirasek, A. [Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia V8W 2Y2, Canada and Department of Physics, University of British Columbia—Okanagan Campus, Kelowna, British Columbia V1V 1V7 (Canada)

2015-04-15

Purpose: To evaluate multislice computed tomography (CT) scanning for fast and reliable readout of radiation therapy (RT) dose distributions using CT polymer gel dosimetry (PGD) and to establish a baseline assessment of image noise and uniformity in an unirradiated gel dosimeter. Methods: A 16-slice CT scanner was used to acquire images through a 1 L cylinder filled with water. Additional images were collected using a single slice machine. The variability in CT number (N{sub CT}) associated with the anode heel effect was evaluated and used to define a new slice-by-slice background subtraction artifact removal technique for CT PGD. Image quality was assessed for the multislice system by evaluating image noise and uniformity. The agreement in N{sub CT} for slices acquired simultaneously using the multislice detector array was also examined. Further study was performed to assess the effects of increasing x-ray tube load on the constancy of measured N{sub CT} and overall scan time. In all cases, results were compared to the single slice machine. Finally, images were collected throughout the volume of an unirradiated gel dosimeter to quantify image noise and uniformity before radiation is delivered. Results: Slice-by-slice background subtraction effectively removes the variability in N{sub CT} observed across images acquired simultaneously using the multislice scanner and is the recommended background subtraction method when using a multislice CT system. Image noise was higher for the multislice system compared to the single slice scanner, but overall image quality was comparable between the two systems. Further study showed N{sub CT} was consistent across image slices acquired simultaneously using the multislice detector array for each detector configuration of the slice thicknesses examined. In addition, the multislice system was found to eliminate variations in N{sub CT} due to increasing x-ray tube load and reduce scanning time by a factor of 4 when compared to

Radiation hardening in sol-gel derived Er3+-doped silica glasses

International Nuclear Information System (INIS)

Hari Babu, B.; León Pichel, Mónica; Ollier, Nadège; El Hamzaoui, Hicham; Bigot, Laurent; Savelii, Inna; Bouazaoui, Mohamed; Poumellec, Bertrand; Lancry, Matthieu; Ibarra, Angel

2015-01-01

The aim of the present paper is to report the effect of radiation on the Er 3+ -doped sol-gel silica glasses. A possible application of these sol-gel glasses could be their use in harsh radiation environments. The sol-gel glasses are fabricated by densification of erbium salt-soaked nanoporous silica xerogels through polymeric sol-gel technique. The radiation-induced attenuation of Er 3+ -doped sol-gel silica is found to increase with erbium content. Electron paramagnetic resonance studies reveal the presence of E′ δ point defects. This happens in the sol-gel aluminum-silica glass after an exposure to γ-rays (kGy) and in sol-gel silica glass after an exposure to electrons (MGy). The concentration levels of these point defects are much lower in γ-ray irradiated sol-gel silica glasses. When the samples are co-doped with Al, the exposure to γ-ray radiation causes a possible reduction of the erbium valence from Er 3+ to Er 2+ ions. This process occurs in association with the formation of aluminum oxygen hole centers and different intrinsic point defects

Tubular array, dielectric, conductivity and electrochemical properties of biodegradable gel polymer electrolyte

Energy Technology Data Exchange (ETDEWEB)

Sudhakar, Y.N. [Department of Chemistry, Manipal Institute of Technology, Manipal, Karnataka (India); Selvakumar, M., E-mail: chemselva78@gmail.com [Department of Chemistry, Manipal Institute of Technology, Manipal, Karnataka (India); Bhat, D. Krishna [Department of Chemistry, National Institute of Technology Karnataka, Surathkal, Mangalore (India)

2014-02-15

Highlights: • A new finding of tubular array of 10–20 μm in length and 1–2 μm in thickness of gel polymer electrolyte (GPE) having 2.2 × 10{sup −3} S cm{sup −1} conductivity is reported. • Thermal and electrochemical characterizations of GPEs show good interaction among the polymer, plasticizer and salt. • GPE based supercapacitor demonstrates high capacitance of 186 F g{sup −1}. • Low temperature studies did not influence much on capacitance values obtained from AC impedance studies. • Charge–discharge exhibits high capacity with excellent cyclic stability and energy density. -- Abstract: A supercapacitor based on a biodegradable gel polymer electrolyte (GPE) has been fabricated using guar gum (GG) as the polymer matrix, LiClO{sub 4} as the doping salt and glycerol as the plasticizer. The scanning electron microscopy (SEM) images of the gel polymer showed an unusual tubular array type surface morphology. FTIR, DSC and TGA results of the GPE indicated good interaction between the components used. Highest ionic conductivity and lowest activation energy values were 2.2 × 10{sup −3} S cm{sup −1} and 0.18 eV, respectively. Dielectric studies revealed ionic behavior and good capacitance with varying frequency of the GPE system. The fabricated supercapacitor showed a maximum specific capacitance value of 186 F g{sup −1} using cyclic voltammetry. Variation of temperature from 273 K to 293 K did not significantly influence the capacitance values obtained from AC impedance studies. Galvanostatic charge–discharge study of supercapacitor indicated that the device has good stability, high energy density and power density.

X-ray computer tomography, ultrasound and vibrational spectroscopic evaluation techniques of polymer gel dosimeters

International Nuclear Information System (INIS)

Baldock, Clive

2004-01-01

Since Gore et al published their paper on Fricke gel dosimetry, the predominant method of evaluation of both Fricke and polymer gel dosimeters has been magnetic resonance imaging (MRI). More recently optical computer tomography (CT) has also been a favourable evaluation method. Other techniques have been explored and developed as potential evaluation techniques in gel dosimetry. This paper reviews these other developments

Dose response evaluation of a low-density normoxic polymer gel dosimeter using MRI

Energy Technology Data Exchange (ETDEWEB)

Haraldsson, P [Medical Radiation Physics, Department of Clinical Sciences, Lund University, Malmoe University Hospital, SE-205 02 Malmoe (Sweden); Department of Radiation Physics, Finsen Centre, Copenhagen University Hospital, DK-2100 Copenhagen (Denmark); Karlsson, A [Medical Radiation Physics, Department of Clinical Sciences, Lund University, Malmoe University Hospital, SE-205 02 Malmoe (Sweden); Wieslander, E [Medical Radiation Physics, Department of Clinical Sciences, Lund University Hospital, SE-221 85 Lund (Sweden); Gustavsson, H [Medical Radiation Physics, Department of Clinical Sciences, Lund University, Malmoe University Hospital, SE-205 02 Malmoe (Sweden); Baeck, S A J [Medical Radiation Physics, Department of Clinical Sciences, Lund University, Malmoe University Hospital, SE-205 02 Malmoe (Sweden)

2006-02-21

A low-density ({approx}0.6 g cm{sup -3}) normoxic polymer gel, containing the antioxidant tetrakis (hydroxymethyl) phosponium (THP), has been investigated with respect to basic absorbed dose response characteristics. The low density was obtained by mixing the gel with expanded polystyrene spheres. The depth dose data for 6 and 18 MV photons were compared with Monte Carlo calculations. A large volume phantom was irradiated in order to study the 3D dose distribution from a 6 MV field. Evaluation of the gel was carried out using magnetic resonance imaging. An approximately linear response was obtained for 1/T2 versus dose in the dose range of 2 to 8 Gy. A small decrease in the dose response was observed for increasing concentrations of THP. A good agreement between measured and Monte Carlo calculated data was obained, both for test tubes and the larger 3D phantom. It was shown that a normoxic polymer gel with a reduced density could be obtained by adding expanded polystyrene spheres. In order to get reliable results, it is very important to have a uniform distribution of the gel and expanded polystyrene spheres in the phantom volume.

Dose response evaluation of a low-density normoxic polymer gel dosimeter using MRI

Science.gov (United States)

Haraldsson, P.; Karlsson, A.; Wieslander, E.; Gustavsson, H.; Bäck, S. Å. J.

2006-02-01

A low-density (~0.6 g cm-3) normoxic polymer gel, containing the antioxidant tetrakis (hydroxymethyl) phosponium (THP), has been investigated with respect to basic absorbed dose response characteristics. The low density was obtained by mixing the gel with expanded polystyrene spheres. The depth dose data for 6 and 18 MV photons were compared with Monte Carlo calculations. A large volume phantom was irradiated in order to study the 3D dose distribution from a 6 MV field. Evaluation of the gel was carried out using magnetic resonance imaging. An approximately linear response was obtained for 1/T2 versus dose in the dose range of 2 to 8 Gy. A small decrease in the dose response was observed for increasing concentrations of THP. A good agreement between measured and Monte Carlo calculated data was obained, both for test tubes and the larger 3D phantom. It was shown that a normoxic polymer gel with a reduced density could be obtained by adding expanded polystyrene spheres. In order to get reliable results, it is very important to have a uniform distribution of the gel and expanded polystyrene spheres in the phantom volume.

Ionic liquids in a poly ethylene oxide cross-linked gel polymer as an electrolyte for electrical double layer capacitor

Science.gov (United States)

Chaudoy, V.; Tran Van, F.; Deschamps, M.; Ghamouss, F.

2017-02-01

In the present work, we developed a gel polymer electrolyte via the incorporation of a room temperature ionic liquid into a cross-linked polymer matrix. The cross-linked gel electrolyte was prepared using a free radical polymerization of methacrylate and dimethacrylate oligomers dissolved in 1-propyl-1-methylpyrrolidinium bis(fluorosulfonyl)imide. Combining the advantages of the ionic liquids and of conventional polymers, the cross-linked gel polymer electrolyte was used both as a separator and as an electrolyte for a leakage-free and non-flammable EDLC supercapacitor. The quasi-all solid-state supercapacitors showed rather good capacitance, power and energy densities by comparison to a liquid electrolyte-based EDLC.

Silica scintillating materials prepared by sol-gel methods

International Nuclear Information System (INIS)

Werst, D.W.; Sauer, M.C. Jr.; Cromack, K.R.; Lin, Y.; Tartakovsky, E.A.; Trifunac, A.D.

1993-01-01

Silica was investigated as a rad-hard alternative to organic polymer hosts for organic scintillators. Silica sol-gels were prepared by hydrolysis of tetramethoxysilane in alcohol solutions. organic dyes were incorporated into the gels by dissolving in methanol at the sol stage of gel formation. The silica sol-gel matrix is very rad-hard. The radiation stability of silica scintillators prepared by this method is dye-limited. Transient radioluminescence was measured following excitation with 30 ps pulses of 20 MeV electrons

Carbon beam dosimetry using VIP polymer gel and MRI

DEFF Research Database (Denmark)

Kantemiris, I; Petrokokkinos, L; Angelopoulos, A

2009-01-01

VIP polymer gel dosimeter was used for Carbon ion beam dosimetry using a 150 MeV/n beam with 10 Gy plateau dose and a SOBP irradiation scheme with 5 Gy Bragg peak dose. The results show a decrease by 8 mm in the expected from Monte Carlo simulation range in water, suggesting that the dosimeter...

Autonomous Oscillation of Nonthermoresponsive Polymers and Gels Induced by the Belousov–Zhabotinsky Reaction

Directory of Open Access Journals (Sweden)

Yusuke Hara

2013-09-01

Full Text Available This review introduces the self-oscillating behavior of two types of nonthermoresponsive polymer systems with Ru catalyst moieties for the Belousov-Zhabotinsky (BZ reaction: one with a poly-vinylpyrrolidone (PVP main chain, and the other with a poly(2-propenamide (polyacrylamide (PAM main chain. The amplitude of the VP-based self-oscillating polymer chain and the activation energy for self-oscillation are hardly affected by the initial concentrations of the BZ substrates. The influences of the initial concentrations of the BZ substrates and the temperature on the period of the swelling-deswelling self-oscillation are examined in detail. Logarithmic plots of the period against the initial concentration of one BZ substrate, when the concentrations of the other two BZ substrates are fixed, show good linear relationships. The period of the swelling-deswelling self-oscillation decreases with increasing temperature, in accordance with the Arrhenius equation. The maximum frequency (0.5 Hz of the poly(VP-co-Ru(bpy3 gel is 20 times that of the poly(NIPAAm-co-Ru(bpy3 gel. It is also demonstrated that the amplitude of the volume self-oscillation for the gel has a tradeoff with the self-oscillation period. In addition, this review reports the self-oscillating behavior of an AM-based self-oscillating polymer chain as compared to that of the VP-based polymer chain.

Study to produce polymer gel for decontamination on the surface of steel, ceramic, plastic, glass

International Nuclear Information System (INIS)

Pham Quynh Luong; Nguyen Van Chinh; Nguyen Thu Trang; Nguyen An Thai; Nguyen Dinh Lam

2015-01-01

Strippable polymer coating is one of the methods for effective surface decontamination. A gel solution of a water soluble polymer, preferably polyvinyl alcohol (PVA) and chelating agent is applied to remove radioisotopes of Cs"1"3"7, Sr"8"5, I"1"3"1, P"3"2 and Tc"9"9"m on the surface of stainless steel, mild steel, ceramic, PVC plastic. After cleaning is completed, the gel solution is dried, formed a strong thin film, which is easily peeled off from a contaminated surface and can be disposed of as radioactive solid waste. Decontamination efficient of this gel polymer for radioisotopes have been studied on the surfaces and compared with Decongel 1101. The influence of decontamination agents, activity, film thickness to decontamination factor have been studied. The infrared spectrophotometer has been conducted to study mechanism of the decontamination for this radioisotope. (author)

Introduction to radiation chemistry of polymer

Energy Technology Data Exchange (ETDEWEB)

Mohd Dahlan, Khairul Zaman [Nuclear Energy Unit, Bangi, Selangor (Malaysia)

1994-12-31

The topics briefly discussed are 1. What are radiation chemistry 2. Type of ionising radiation 3. gamma rays versus electron beam 4. Interaction of radiation with matters 5. What is polymers 6. Techniques of crosslinking 7. Crosslinking of polymers i.e. polyethylene, ethylene copolymer, polypropylene, polyamides, polyvinyl chloride, natural rubber.

Introduction to radiation chemistry of polymer

International Nuclear Information System (INIS)

Khairul Zaman Mohd Dahlan

1994-01-01

The topics briefly discussed are 1. What are radiation chemistry 2. Type of ionising radiation 3. gamma rays versus electron beam 4. Interaction of radiation with matters 5. What is polymers 6. Techniques of crosslinking 7. Crosslinking of polymers i.e. polyethylene, ethylene copolymer, polypropylene, polyamides, polyvinyl chloride, natural rubber

Sol-gel derived polymer composites for energy storage and conversion

Science.gov (United States)

Han, Kuo

Sol-gel process is a simple chemistry to convert the small precursor molecules into an inorganic polymer, which could be applied to synthesize inorganic materials, modify the interface of materials, bridge the organic and inorganic materials, etc. In this dissertation, novel sol-gel derived composites have been developed for high dielectric breakdown capacitors, low high frequency loss capacitors and flexible piezoelectrics. Numerous efforts have been made in the past decades to improve the energy storage capability of composite materials by incorporating nanometer scale ceramic addictives with high dielectric permittivity into dielectric polymers with high breakdown strength. However, most composites suffer from the low breakdown strength and make the potential gain in energy density small. Here, a new chemical strategy is proposed that, through sol-gel reactions between ceramic precursors and functional groups at the end of the functionalized Poly(vinylidene fluoride -co-chlorotrifluoroethylene) chains, amorphous low permittivity ceramics was in-situ generated in the polymer matrix and cross-linked the polymer chains simultaneously. By carefully tuning precursors, the polymer/precursors feeding ratios, a series of nanocomposites were systematically designed. All the samples are comprehensively characterized and the structure-property correlations are well investigated. The optimal samples exhibit higher breakdown strength than the pristine polymer. The enhanced breakdown strength ascribed to low contrast in permittivity, great dispersion and improved electrical and mechanical properties. This newly developed approach has shown great promise for new composite capacitors. The percolative polymer composites have recently exhibited great potential in energy storage due to their high dielectric permittivities at the neighborhood of the percolation threshold. Yet high energy dissipation and poor voltage endurance of the percolative composites resulted from electrical

Monte Carlo verification of polymer gel dosimetry applied to radionuclide therapy: a phantom study

International Nuclear Information System (INIS)

Gear, J I; Partridge, M; Flux, G D; Charles-Edwards, E

2011-01-01

This study evaluates the dosimetric performance of the polymer gel dosimeter 'Methacrylic and Ascorbic acid in Gelatin, initiated by Copper' and its suitability for quality assurance and analysis of I-131-targeted radionuclide therapy dosimetry. Four batches of gel were manufactured in-house and sets of calibration vials and phantoms were created containing different concentrations of I-131-doped gel. Multiple dose measurements were made up to 700 h post preparation and compared to equivalent Monte Carlo simulations. In addition to uniformly filled phantoms the cross-dose distribution from a hot insert to a surrounding phantom was measured. In this example comparisons were made with both Monte Carlo and a clinical scintigraphic dosimetry method. Dose-response curves generated from the calibration data followed a sigmoid function. The gels appeared to be stable over many weeks of internal irradiation with a delay in gel response observed at 29 h post preparation. This was attributed to chemical inhibitors and slow reaction rates of long-chain radical species. For this reason, phantom measurements were only made after 190 h of irradiation. For uniformly filled phantoms of I-131 the accuracy of dose measurements agreed to within 10% when compared to Monte Carlo simulations. A radial cross-dose distribution measured using the gel dosimeter compared well to that calculated with Monte Carlo. Small inhomogeneities were observed in the dosimeter attributed to non-uniform mixing of monomer during preparation. However, they were not detrimental to this study where the quantitative accuracy and spatial resolution of polymer gel dosimetry were far superior to that calculated using scintigraphy. The difference between Monte Carlo and gel measurements was of the order of a few cGy, whilst with the scintigraphic method differences of up to 8 Gy were observed. A manipulation technique is also presented which allows 3D scintigraphic dosimetry measurements to be compared to polymer

Recent trends in radiation polymer chemistry

International Nuclear Information System (INIS)

Okamura, S.

1993-01-01

This book contains five contributions with the following topics: 1. Electron Spin Echo Studies of Free Radicals in Irradiated Polymers (H. Yoshida, T. Ichikawa); 2. Application of Pulse Radiolysis to the Study of Polymers and Polymerizations (M. Ogasawara); 3. Radiation Synthesis of Polymeric Materials for Biomedical and Biochemical Applications (I. Kaetsu); 4. Radiation Effects of Ion Beams on Polymers (S. Tagawa); and 5. Polymer Materials for Fusion Reactors (H. Yamaoka). (orig./MM). 74 figs., 12 tabs

Application of controlled radiation-induced degradation in polymers: less exploited aspect of radiation processing of polymers

International Nuclear Information System (INIS)

Haji Saeid, M.; Guven, O.

2007-01-01

Industrial use of ionizing radiation treatment has been most successful in applications related to polymeric materials. The polymer, plastics and rubber industries have benefited from the unique advantages of ionizing radiation since its inception as an industrial tool to modify their properties and manufacture novel materials with value addition to the end product. The established and emerging applications of electron beam processing of polymers are based on the well known ultimate effects of ionizing radiation on polymers namely, crosslinking, curing, grafting and chain scissioning. Radiation-induced crosslinking dominates most applications, whereas the chain scissioning effect is much less explored and currently limited to radiation-induced degradation of Teflon, cellulose and polypropylene. The controlling of radiation-induced degradation for achieving a target average molecular weight or distribution has been evaluated for some polysaccharides, biopolymers and waste inner tubes whereas mitigation of the degradative effects of radiation has been analyzed from the point of view of using certain stabilizers, copolymers and annealing at an appropriate temperature. Several new or highly specialized techniques such as positron annihilation lifetime spectroscopy. Rutherford backscattering, elastic recoil detection analysis and solid waste NMR spectroscopy and gas chromatography-mass spectroscopy have been applied to the study or radiation-induced degradation. New information has been collected on the morphological changes associated with radiation-induced degradation processes, including chain scission, oxidation and free volume alteration. The IAEA coordinated research project (CRP) on Controlling of Degradation Effects in Radiation Processing of Polymers dealt with the role and importance of using ionizing radiation in controlling properties of natural and synthetic polymers through its degradative effect. This paper provides a summary of most important results

New trends in radiation processing of polymers

International Nuclear Information System (INIS)

Chmielewski, Andrzej G.

2005-01-01

Nowadays, the modification of polymers covers radiation cross-linking, radiation induced polymerization (graft polymerization and curing) and the degradation of polymers. The success of radiation technology for the processing of synthetic polymers can be attributed to two reasons, namely the easiness of processing in various shapes and sizes and, secondly, most of these polymers undergo cross-linking reaction upon exposure to radiation. years, natural polymers are being looked at again with renewed interest because of their unique characteristics like inherent biocompatibility, biodegradability and easy availability. However the recent progress in the field regards development of new processing methods and technical solutions. No other break trough technologies or products based on synthetic polymers are reported recently. The future progress, both from scientific and practical points of view, concerns nanotechnology and natural polymer processing. Overview of the subject, including the works performed in the Institute of the author is presented in the paper. (author)

Effect of ionizing radiation on properties of acrylic pressure sensitive adhesives

International Nuclear Information System (INIS)

Panta, P.P.; Zimek, Z.A.; Giuszewski, W.; Kowalewski, R.; Wojtynska, E.; Wnuk, A.

1998-01-01

Pressure-sensitive adhesives for technical application are widely produced. The biological properties of adhesives depend on the type of monomers used. The available literature data as experience of the authors of this study in the area of pressure-sensitive acrylic adhesive, polymers used in medicine, polymerisation in aqueous media, radiation sterilization, permit to make an assumption that it is possible to elaborate the technology of production of pressure-sensitive adhesives in aqueous emulsion for medical applications. Identification of phenomena influencing the adhesive properties, especially its adhesion, cohesion, tack and durability is of great importance. The control of polymer structure is performed by means of adequate selection of conditions of synthesis and parameters of radiation processing. The authors investigate the influence on the final products of such factors as the type and amount of monomers used, their mutual ratio, as well as the ratio monomers and the dose of ionising radiation. There is no available literature information concerning the investigation of resistance of acrylic emulsion adhesive to sterilisation by electron beam. It is known from unpublished research that some adhesives are resistant to radiation, while others undergo destruction. It probably depends on the composition of emulsion, specifically on the additives which modify adhesives. Simultaneous achievement of good cohesion and adhesion in the case of such types of pressure sensitive adhesives is very difficult pressure sensitive adhesives is very difficult

A Polymer Electrolyte for Dye-Sensitized Solar Cells Based on a Poly(Polyvinylidenefluoride-Co-Hexafluoropropylene)/Hydroxypropyl Methyl Cellulose Blend

Science.gov (United States)

Won, Lee Ji; Kim, Jae Hong; Thogiti, Suresh

2018-03-01

A novel polymer blend electrolyte for dye-sensitized solar cells (DSSCs) was synthesized by quasi-solidifying a liquid-based electrolyte containing an iodide/triiodide redox couple and supporting salts with a mixture of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and indigenous hydroxypropyl methyl cellulose (HPMC). A high ionic conductivity of 8.8 × 10-4 S cm-1 was achieved after introducing 5 wt% of HPMC with respect to the weight of PVDH-HFP. DSSCs were fabricated using gel polymer blend electrolytes, and the J-V characteristics of the fabricated devices were analyzed. Under optimal conditions, the photovoltaic conversion efficiency of cells with the novel HPMC-blended gel electrolyte (5.34%) was significantly greater than that of cells without HPMC (3.97%).

Utilization of SRNL-developed radiation-resistant polymer in high radiation environments

Energy Technology Data Exchange (ETDEWEB)

Skibo, A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-09-27

The radiation-resistant polymer developed by the Savannah River National Laboratory is adaptable for multiple applications to enhance polymer endurance and effectiveness in radiation environments. SRNL offers to collaborate with TEPCO in evaluation, testing, and utilization of SRNL’s radiation-resistant polymer in the D&D of the Fukushima Daiichi NPS. Refinement of the scope and associated costs will be conducted in consultation with TECPO.

Radiation resistance of polymer materials. Degradation evaluation by accelerated testing for application condition

International Nuclear Information System (INIS)

Seguchi, Tadao; Tamura, Kiyotoshi; Sorimachi, Masami

2010-02-01

This paper presents re-evaluated radiation resistance property data of polymer materials, which had been tested in past times in TAKASAKI Quantum Beam Science Directorate, for the future study of ageing evaluation of low voltage electric cable insulation materials used in light-water nuclear reactors. The radiation resistance of 25 types of plastics and rubbers materials applied in practical environments was evaluated by the accelerated testing of gamma-ray irradiation under oxygen pressure, and was compared with the radiation resistance determined from the traditional testing by irradiation with a high dose rate in air. The polymer materials were formulated to be similar or equivalent to practical materials, and the most of formulation (chemical compounds and quantities) were described. For all materials, the tensile properties (elongation at break, ultimate strength, 100% or 200% modulus), electric resistivity, gel-fraction, and density were measured after irradiation in oxidation conditions and irradiation in air with a high dose rate (non-oxidation conditions). The data of relations between each properties and total dose at various conditions were compiled, and the relations among the changes of mechanical properties, electrical properties, and radiation induced chemical reactions were discussed. (author)

Radiation degradation of α-substituted acrylate polymers and copolymers

International Nuclear Information System (INIS)

Helbert, J.N.; Caplan, P.J.; Poindexter, E.H.

1977-01-01

Radiation degradation is observed in poly(methyl α-chloroacrylate), poly(methyl α-cyanoacrylate), and poly (α-chloroacrylonitrile) homopolymers and their respective MMA copolymers when γ-irradiated in vacuo. Polymer degradation susceptibilities are quantified in terms of G(scission radicals) and G(scission) -- G(crosslinks), measured by EPR and membrane osmometry, respectively; values by these two methods are compared. Higher G(rads) values ranging from 2 to 6 and [G(s) -- G(x)] values ranging from 2 to 11 are obtained for the substituted polymers and copolymers relative to the values for PMMA (1.6; 1.9), a standard e-beam positive resist, which suggests that these modified polymers are more sensitive e-beam resists than PMMA

Evaluation of polymer gels and MRI as a 3-D dosimeter for intensity-modulated radiation therapy.

Science.gov (United States)

Low, D A; Dempsey, J F; Venkatesan, R; Mutic, S; Markman, J; Mark Haacke, E; Purdy, J A

1999-08-01

BANG gel (MGS Research, Inc., Guilford, CT) has been evaluated for measuring intensity-modulated radiation therapy (IMRT) dose distributions. Treatment plans with target doses of 1500 cGy were generated by the Peacock IMRT system (NOMOS Corp., Sewickley, PA) using test target volumes. The gels were enclosed in 13 cm outer diameter cylindrical glass vessels. Dose calibration was conducted using seven smaller (4 cm diameter) cylindrical glass vessels irradiated to 0-1800 cGy in 300 cGy increments. Three-dimensional maps of the proton relaxation rate R2 were obtained using a 1.5 T magnetic resonance imaging (MRI) system (Siemens Medical Systems, Erlangen, Germany) and correlated with dose. A Hahn spin echo sequence was used with TR = 3 s, TE = 20 and 100 ms, NEX = 1, using 1 x 1 x 3 mm3 voxels. The MRI measurements were repeated weekly to identify the gel-aging characteristics. Ionization chamber, thermoluminescent dosimetry (TLD), and film dosimetry measurements of the IMRT dose distributions were obtained to compare against the gel results. The other dosimeters were used in a phantom with the same external cross-section as the gel phantom. The irradiated R2 values of the large vessels did not precisely track the smaller vessels, so the ionization chamber measurements were used to normalize the gel dose distributions. The point-to-point standard deviation of the gel dose measurements was 7.0 cGy. When compared with the ionization chamber measurements averaged over the chamber volume, 1% agreement was obtained. Comparisons against radiographic film dose distribution measurements and the treatment planning dose distribution calculation were used to determine the spatial localization accuracy of the gel and MRI. Spatial localization was better than 2 mm, and the dose was accurately determined by the gel both within and outside the target. The TLD chips were placed throughout the phantom to determine gel measurement precision in high- and low-dose regions. A

A colourimetric method for the determination of the degree of chemical cross-linking in aspartic acid-based polymer gels

Directory of Open Access Journals (Sweden)

B. Gyarmati

2015-02-01

Full Text Available A 2,4,6-trinitrobenzenesulphonic acid (TNBS-based assay is developed to determine the degree of chemical cross-linking in aspartic acid-based polymer gels. The conventional colourimetric method for the quantitative determination of amine groups is difficult to use in polymer networks; thus, an improved method is developed to analyse polymer gels swollen in dimethyl sulfoxide (DMSO. Reaction products of the derivatizing reaction are examined by NMR. The chemical stability of the reagent is increased in DMSO, and the method shows satisfactory linearity and accuracy. The degree of chemical cross-linking in the investigated gels is close to its theoretical maximum, but the conversion of the pendant amine groups to cross-linking points is strongly dependent on the feed composition of the gels.

Radiation detectors based by polymer materials

International Nuclear Information System (INIS)

Cherestes, Margareta; Cherestes, Codrut; Constantinescu, Livia

2004-01-01

Scintillation counters make use of the property of certain chemical compounds to emit short light pulses after excitation produced by the passage of charged particles or photons of high energy. These flashes of light are detected by a photomultiplier tube that converts the photons into a voltage pulse. The light emitted from the detector also can be collected, focussed and dispersed by a CCD detector. The study of the evolution of the light emission and of the radiation damage under irradiation is a primary topic in the development of radiation hard polymer based scintillator. Polymer scintillator thin films are used in monitoring radiation beam intensities and simultaneous counting of different radiations. Radiation detectors have characteristics which depend on: the type of radiation, the energy of radiation, and the material of the detector. Three types of polymer thin films were studied: a polyvinyltoluene based scintillator, fluorinated polyimide and PMMA. (authors)

Radiation damage of polymers in ultrasonic fields

Energy Technology Data Exchange (ETDEWEB)

Anbalagan, Poornnima

2008-07-01

Radiation damage has always been a topic of great interest in various fields of sciences. In this work, an attempt is made to probe into the effect of subthreshold ultrasonic waves on the radiation damage created by irradiation of deuterons in polymer samples wherein the polymer samples act as model systems. Two equal volumes of radiation damage were produced in a single polymer sample wherein a standing wave of ultrasound was introduced into one. Three polymers namely, Polycarbonate, Polymethylmethacrylate and Polyvinyl chloride were used in this work. Four independent techniques were used to analyze the irradiated samples and visualize the radiation damage. Interferometric measurements give a measure of the refractive index modulation in the irradiated sample. Polymers, being transparent, do not absorb in the visible region of the electromagnetic spectrum. UV-Vis absorption spectroscopy shows absorption peaks in the visible region in irradiated polymer samples. Ion irradiation causes coloration of polymers. The light microscope is used to measure the absorption of white light by the irradiated polymers. Positron annihilation spectroscopy is used to obtain a measure of the open volume created by irradiation in polymers. A comparison between the irradiated region and the region exposed to ultrasonic waves simultaneously with irradiation in a polymer sample shows the polymer specific influence of the ultrasonic standing wave. (orig.)

Radiation damage of polymers in ultrasonic fields

International Nuclear Information System (INIS)

Anbalagan, Poornnima

2008-01-01

Radiation damage has always been a topic of great interest in various fields of sciences. In this work, an attempt is made to probe into the effect of subthreshold ultrasonic waves on the radiation damage created by irradiation of deuterons in polymer samples wherein the polymer samples act as model systems. Two equal volumes of radiation damage were produced in a single polymer sample wherein a standing wave of ultrasound was introduced into one. Three polymers namely, Polycarbonate, Polymethylmethacrylate and Polyvinyl chloride were used in this work. Four independent techniques were used to analyze the irradiated samples and visualize the radiation damage. Interferometric measurements give a measure of the refractive index modulation in the irradiated sample. Polymers, being transparent, do not absorb in the visible region of the electromagnetic spectrum. UV-Vis absorption spectroscopy shows absorption peaks in the visible region in irradiated polymer samples. Ion irradiation causes coloration of polymers. The light microscope is used to measure the absorption of white light by the irradiated polymers. Positron annihilation spectroscopy is used to obtain a measure of the open volume created by irradiation in polymers. A comparison between the irradiated region and the region exposed to ultrasonic waves simultaneously with irradiation in a polymer sample shows the polymer specific influence of the ultrasonic standing wave. (orig.)

A study on the reproducibility and spatial uniformity of N-isopropylacrylamide polymer gel dosimetry using a commercial 10X fast optical-computed tomography scanner

International Nuclear Information System (INIS)

Chang, Y J; Lin, J Q; Hsieh, B T; Chen, C H

2013-01-01

This study investigated the reproducibility and spatial uniformity of N-isopropylacrylamide (NIPAM) polymer gel as well as the reproducibility of a NIPAM polymer gel dosimeter. A commercial 10X fast optical computed tomography scanner (OCTOPUS-10X, MGS Research, Inc., Madison, CT, USA) was used as the readout tool of the NIPAM polymer gel dosimeter. A cylindrical NIPAM gel phantom measuring 10 cm (diameter) by 10 cm (height) by 3 mm (thickness) was irradiated by the four-field box treatment with a field size of 3 cm × 3 cm. The dose profiles were found to be consistent at the depths of 2.0 cm to 5.0 cm for two independent gel phantom batches, and the average uncertainty was less than 2%. The gamma pass rates were calculated to be between 94% and 95% at depths of 40 mm for two independent gel phantom batches using 4% dose difference and 4 mm distance-to-agreement criterion. The NIPAM polymer gel dosimeter was highly reproducible and spatially uniform. The results highlighted the potential of the NIPAM polymer gel dosimeter in radiotherapy.

Radiation processing of natural polymer

International Nuclear Information System (INIS)

Khairul Zaman; Kamaruddin Hashim; Zulkafli Ghazali; Mohd Hilmi Mahmood; Jamaliah Sharif

2006-01-01

Radiation processing of natural polymer has been the subject of interest of countries in this region in the past 5 ∼ 7 years. Although some of the output of the research have been commercialized in particular for the applications in the agriculture and healthcare sectors, the potential applications of radiation processing of natural polymers in the medical sector are yet to be fully understood and developed. (author)

A systematic approach to determine optimal composition of gel used in radiation therapy

International Nuclear Information System (INIS)

Chang, Yuan-Jen; Hsieh, Bor-Tsung; Liang, Ji-An

2011-01-01

The design of experiment was used to find the optimal composition of N-isopropyl acrylamide (NIPAM) gel. Optical computed tomography was used to scan the polymer gel dosimeter, which was irradiated from 0 to 20 Gy. The study was conducted following a statistical method using a two-level fractional factorial plan involving four variables (gelatin-5% and 6%, NIPAM-3% and 5%, Bis-2.5% and 3%, and THPC-5 and 10 mM). We produced three batches of gels of the same composition to replicate the experiments. Based on the statistical analysis, a regression model was built. The optimal gel composition for the dose range 0-15 Gy with linearity up to 1.000 is as follows: gelatin (5.67%), NIPAM (5%), Bis (2.56%), and THPC (10 mM). The dose response of the NIPAM polymer gel attains stability about 24 h after irradiation and remains stable up to 3 months.

Radiation Synthesis of Superabsorbent Polymers Based on Natural Polymers

International Nuclear Information System (INIS)

Sen, Murat; Hayrabolulu, Hande

2010-01-01

The objectives of proposed research contract were first synthesize superabsorbent polymers based on natural polymers to be used as disposable diapers and soil conditioning materials in agriculture, horticulture and other super adsorbent using industries. We have planned to use the natural polymers; locust beam gum, tara gum, guar gum and sodium alginate on the preparation of natural superabsorbent polymers(SAP). The aqueous solution of natural polymers and their blends with trace amount of monomer and cross-linking agents will be irradiated in paste like conditions by gamma rays for the preparation of cross-linked superabsorbent systems. The water absorption and deswellling capacity of prepared super adsorbents and retention capacity, absorbency under load, suction power, swelling pressure and pet-rewet properties will be determined. Use of these materials instead of synthetic super absorbents will be examined by comparing the performance of finished products. The experimental studies achieved in the second year of project mainly on the effect of radiation on the chemistry of sodium alginate polymers in different irradiation conditions and structure-property relationship particularly with respect to radiation induced changes on the molecular weight of natural polymers and preliminary studies on the synthesis of natural-synthetic hydride super adsorbent polymers were given in details

Post-modification by γ-radiation of VDF-based polymers: Electrochemical capacitor membrane application

International Nuclear Information System (INIS)

Dumas, L.

2012-01-01

This work deals with the modification of VDF-based polymer induced by γ-radiation as the polymer may be used in electrochemical super-capacitors. The main objective was to limit the swelling of the fluorinated matrix with a given electrolyte while a good wetting of the polymer by the liquid was also required. As the main basic process involved in polymer radiolysis is the formation of radicals, a part of the work was dedicated to the study of such species by using Electron Spin Resonance spectroscopy. A simulation model of ESR spectra was established in order to identify and quantify each radical species. The effect of several parameters such as radiation dose, annealing time or the nature of polymer matrix on the concentration of each species where investigated. A relation with the evolution of the crosslink density of the network formed during the radiolysis was proposed. In addition, one of the key steps of this work was to study the radiation crosslinking ability of VDF-based polymers and find a way to increase the crosslink density. This was achieved by incorporating, prior to the radiation process, a radiation sensitive cross linker: TAIC. Finally, a new strategy based on the modification of surface properties of PVDF was investigated. It consists in the radiation grafting of penta-fluor-styrene onto PVDF surface followed by the chemo-selective functionalization of the grafted segments. As a conclusion, the different approaches used in this thesis allowed us to understand the radiolysis of VDF-based polymers and take advantage of the elementary process involved in this type of chemistry, to build up robust and promising strategies for tuning properties. (author)

Development of Polymer Gel Systems to Improve Volumetric Sweep and Reduce Producing Water/Oil Ratios

Energy Technology Data Exchange (ETDEWEB)

G. Paul Willhite; Stan McCool; Don W. Green; Min Cheng; Feiyan Chen

2005-12-31

Gelled polymer treatments are applied to oil reservoirs to increase oil production and to reduce water production by altering the fluid movement within the reservoir. This report describes the results of a 42-month research program that focused on the understanding of gelation chemistry and the fundamental mechanisms that alter the flows of oil and water in reservoir rocks after a gel treatment. Work was conducted on a widely applied system in the field, the partially hydrolyzed polyacrylamide-chromium acetate gel. Gelation occurs by network formation through the crosslinking of polyacrylamide molecules as a result of reaction with chromium acetate. Pre-gel aggregates form and grow as reactions between chromium acetate and polyacrylamide proceed. A rate equation that describes the reaction between chromium acetate and polymer molecules was regressed from experimental data. A mathematical model that describes the crosslinking reaction between two polymer molecules as a function of time was derived. The model was based on probability concepts and provides molecular-weight averages and molecular-weight distributions of the pre-gel aggregates as a function of time and initial system conditions. Average molecular weights of pre-gel aggregates were measured as a function of time and were comparable to model simulations. Experimental methods to determine molecular weight distributions of pre-gel aggregates were unsuccessful. Dissolution of carbonate minerals during the injection of gelants causes the pH of the gelant to increase. Chromium precipitates from solution at the higher pH values robbing the gelant of crosslinker. Experimental data on the transport of chromium acetate solutions through dolomite cores were obtained. A mathematical model that describes the transport of brine and chromium acetate solutions through rocks containing carbonate minerals was used to simulate the experimental results and data from literature. Gel treatments usually reduce the permeability

Allopurinol gel mitigates radiation-induced mucositis and dermatitis

International Nuclear Information System (INIS)

Kitagawa, Junichi; Nasu, Masanori; Okumura, Hayato; Matsumoto, Shigeji; Shibata, Akihiko; Makino, Kimiko; Terada, Hiroshi

2008-01-01

It has not been verified whether allopurinol application is beneficial in decreasing the severity of radiation-induced oral mucositis and dermatitis. Rats were divided into 4 groups and received 15 Gy irradiation on the left whisker pad. Group 1 received only irradiation. Group 2 was maintained by applying allopurinol/carrageenan-mixed gel (allopurinol gel) continuously from 2 days before to 20 days after irradiation. Group 3 had allopurinol gel applied for 20 days after radiation. Group 4 was maintained by applying carrageenan gel continuously from 2 days before to 20 days after irradiation. The intra oral mucosal and acute skin reactions were assessed daily using mucositis and skin score systems. The escape thresholds for mechanical stimulation to the left whisker pad were measured daily. In addition, the irradiated tissues at the endpoint of this study were compared with naive tissue. Escape threshold in group 2 was significantly higher than that in group 1, and mucositis and skin scores were much improved compared with those of group 1. Concerning escape threshold, mucositis and skin scores in group 3 began to improve 10 days after irradiation. Group 4 showed severe symptoms of mucositis and dermatitis to the same extent as that observed in group 1. In the histopathological study, the tissues of group 1 showed severe inflammatory reactions, compared with those of group 2. These results suggest that allopurinol gel application can mitigate inflammation reactions associated with radiation-induced oral mucositis and dermatitis. (author)

Progress in radiation processing of polymers

Science.gov (United States)

Chmielewski, Andrzej G.; Haji-Saeid, Mohammad; Ahmed, Shamshad

2005-07-01

Modification in polymeric structure of plastic material can be brought either by conventional chemical means or by exposure to ionization radiation from ether radioactive sources or highly accelerated electrons. The prominent drawbacks of chemical cross-linking typically involve the generation of noxious fumes and by products of peroxide degradation. Both the irradiation sources have their merits and limitations. Increased utilization of electron beams for modification and enhancement of polymer materials has been in particular witnessed over the past 40 years. The paper highlights several recent cases of EB utilization to improve key properties of selected plastic products. In paper is provided a survey of radiation processing methods of industrial interest, encompassing technologies which are already commercially well established, through developments in the active R&D stage which show pronounced promise for future commercial use. Radiation cross-linking technologies discussed include: application in cable and wire, application in rubber tyres, radiation vulcanization of rubber latex, development of radiation crosslinked SiC fiber, polymer recycling, development of gamma compatible pp, hydrogels etc. Over the years, remarkable advancement has been achieved in radiation processing of natural polymers. Role of radiation in improving the processing of temperature of PCL for use as biodegradable polymer, in accelerated breakdown of cellulose into viscose and enhancement in yields of chitin/chitosan from sea-food waste, is described.

Progress in radiation processing of polymers

Energy Technology Data Exchange (ETDEWEB)

Chmielewski, Andrzej G. [International Atomic Energy Agency, Industrial Applications and Chemistry Section, Division of Physical and Chemical Sciences, Department of Nuclear Sciences and Applications, Wagramer Street 5, Vienna 1400 (Austria) and Department of Process and Chemical Engineering, Warsaw University of Technology, Warsaw (Poland)]. E-mail: a-g.chmielewski@iaea.org; Haji-Saeid, Mohammad [International Atomic Energy Agency, Industrial Applications and Chemistry Section, Division of Physical and Chemical Sciences, Department of Nuclear Sciences and Applications, Wagramer Street 5, Vienna 1400 (Austria); Ahmed, Shamshad [Applied Chemistry Laboratories, Pakistan Institute of Nuclear Science and Technology, P.O. Box Nilore, Islamabad (Pakistan)

2005-07-01

Modification in polymeric structure of plastic material can be brought either by conventional chemical means or by exposure to ionization radiation from ether radioactive sources or highly accelerated electrons. The prominent drawbacks of chemical cross-linking typically involve the generation of noxious fumes and by products of peroxide degradation. Both the irradiation sources have their merits and limitations. Increased utilization of electron beams for modification and enhancement of polymer materials has been in particular witnessed over the past 40 years. The paper highlights several recent cases of EB utilization to improve key properties of selected plastic products. In paper is provided a survey of radiation processing methods of industrial interest, encompassing technologies which are already commercially well established, through developments in the active R and D stage which show pronounced promise for future commercial use. Radiation cross-linking technologies discussed include: application in cable and wire, application in rubber tyres, radiation vulcanization of rubber latex, development of radiation crosslinked SiC fiber, polymer recycling, development of gamma compatible pp, hydrogels etc. Over the years, remarkable advancement has been achieved in radiation processing of natural polymers. Role of radiation in improving the processing of temperature of PCL for use as biodegradable polymer, in accelerated breakdown of cellulose into viscose and enhancement in yields of chitin/chitosan from sea-food waste, is described.

Progress in radiation processing of polymers

International Nuclear Information System (INIS)

Chmielewski, Andrzej G.; Haji-Saeid, Mohammad; Ahmed, Shamshad

2005-01-01

Modification in polymeric structure of plastic material can be brought either by conventional chemical means or by exposure to ionization radiation from ether radioactive sources or highly accelerated electrons. The prominent drawbacks of chemical cross-linking typically involve the generation of noxious fumes and by products of peroxide degradation. Both the irradiation sources have their merits and limitations. Increased utilization of electron beams for modification and enhancement of polymer materials has been in particular witnessed over the past 40 years. The paper highlights several recent cases of EB utilization to improve key properties of selected plastic products. In paper is provided a survey of radiation processing methods of industrial interest, encompassing technologies which are already commercially well established, through developments in the active R and D stage which show pronounced promise for future commercial use. Radiation cross-linking technologies discussed include: application in cable and wire, application in rubber tyres, radiation vulcanization of rubber latex, development of radiation crosslinked SiC fiber, polymer recycling, development of gamma compatible pp, hydrogels etc. Over the years, remarkable advancement has been achieved in radiation processing of natural polymers. Role of radiation in improving the processing of temperature of PCL for use as biodegradable polymer, in accelerated breakdown of cellulose into viscose and enhancement in yields of chitin/chitosan from sea-food waste, is described

3-D dose verification for IMRT using optical CT based polymer gel dosimetry

Energy Technology Data Exchange (ETDEWEB)

Wuu, C [Department of Radiation Oncology, Columbia University, New York, New York (United States); Xu, Y [Department of Radiation Oncology, Columbia University, New York, New York (United States); Maryanski, M J [Department of Radiation Oncology, Columbia University, New York, New York (United States); MGS Research Inc., Madison, Connecticut (United States)

2004-01-01

In this study BANG[reg] polymer gels in conjunction with OCTOPUS{sup TM} optical CT scanner (MGS Research Inc., Madison, CT) was employed to measure the relative 3D dose distribution of an IMRT treatment. Measured relative dose distributions from the gel measurement were compared with those from treatment planning system calculations and EDR2 film measurements with regard to planar dose distributions in axial, coronal, and sagittal orientations.

3-D dose verification for IMRT using optical CT based polymer gel dosimetry

International Nuclear Information System (INIS)

Wuu, C; Xu, Y; Maryanski, M J

2004-01-01

In this study BANG[reg] polymer gels in conjunction with OCTOPUS TM optical CT scanner (MGS Research Inc., Madison, CT) was employed to measure the relative 3D dose distribution of an IMRT treatment. Measured relative dose distributions from the gel measurement were compared with those from treatment planning system calculations and EDR2 film measurements with regard to planar dose distributions in axial, coronal, and sagittal orientations

Transport Phenomena in Gel

Directory of Open Access Journals (Sweden)

Masayuki Tokita

2016-05-01

Full Text Available Gel becomes an important class of soft materials since it can be seen in a wide variety of the chemical and the biological systems. The unique properties of gel arise from the structure, namely, the three-dimensional polymer network that is swollen by a huge amount of solvent. Despite the small volume fraction of the polymer network, which is usually only a few percent or less, gel shows the typical properties that belong to solids such as the elasticity. Gel is, therefore, regarded as a dilute solid because its elasticity is much smaller than that of typical solids. Because of the diluted structure, small molecules can pass along the open space of the polymer network. In addition to the viscous resistance of gel fluid, however, the substance experiences resistance due to the polymer network of gel during the transport process. It is, therefore, of importance to study the diffusion of the small molecules in gel as well as the flow of gel fluid itself through the polymer network of gel. It may be natural to assume that the effects of the resistance due to the polymer network of gel depends strongly on the network structure. Therefore, detailed study on the transport processes in and through gel may open a new insight into the relationship between the structure and the transport properties of gel. The two typical transport processes in and through gel, that is, the diffusion of small molecules due to the thermal fluctuations and the flow of gel fluid that is caused by the mechanical pressure gradient will be reviewed.

Hydroxyapatite scaffolds processed using a TBA-based freeze-gel casting/polymer sponge technique.

Science.gov (United States)

Yang, Tae Young; Lee, Jung Min; Yoon, Seog Young; Park, Hong Chae

2010-05-01

A novel freeze-gel casting/polymer sponge technique has been introduced to fabricate porous hydroxyapatite scaffolds with controlled "designer" pore structures and improved compressive strength for bone tissue engineering applications. Tertiary-butyl alcohol (TBA) was used as a solvent in this work. The merits of each production process, freeze casting, gel casting, and polymer sponge route were characterized by the sintered microstructure and mechanical strength. A reticulated structure with large pore size of 180-360 microm, which formed on burn-out of polyurethane foam, consisted of the strut with highly interconnected, unidirectional, long pore channels (approximately 4.5 microm in dia.) by evaporation of frozen TBA produced in freeze casting together with the dense inner walls with a few, isolated fine pores (<2 microm) by gel casting. The sintered porosity and pore size generally behaved in an opposite manner to the solid loading, i.e., a high solid loading gave low porosity and small pore size, and a thickening of the strut cross section, thus leading to higher compressive strengths.

Radiation Modification of Some Natural Polymers and Their Potential Applications

International Nuclear Information System (INIS)

Refaee, A.M.E.A.

2012-01-01

(PAAm) which is one of the most popular polymers used to reduce water runoff and increase infiltration rates in field agricultural applications. There are different methods to improve water holding capacity of PAAm among of them; adjusting the density of its crosslinking network structure. Radiation technique is promising for preparation of hydrogels because a polymer in aqueous solution or in the water swollen state readily undergoes crosslinking on irradiation to yield a gel-like material. Irradiation dose can control the crosslinking yield of polymer. Addition of few amount of degraded natural polymer during the irradiation processing of PAAm can also reduce the hydrogel network structural density and influences its water holding capacity. Moreover, the low molecular weight natural polymer like alginate or chitosan incorporated in PAAm hydrogel help in promoting the plant growth when such hydrogels used as water supplied soil conditioner. In this connection, the crosslinked copolymers of γ-rays degraded alginate, chitosan or both of them with PAAm were prepared using ionizing radiation. The preparation conditions of the polyacrylamide/alginate (PAAm/Alg), polyacrylamide/chitosan (PAAm/CS) and polyacrylamide/alginate/chitosan (PAAm/Alg/CS) crosslinked hydrogels, such as the effect of the irradiation dose and the copolymer composition on the matrix gel content and water absorbency will be studied. The effect of different types of cations or fertilizers or buffers of different pH's on water absorbency of prepared hydrogels will be investigated. The possible use of such copolymer hydrogels in the field of agriculture for some plants will be investigated.

The radiation chemistry of polymer composites

International Nuclear Information System (INIS)

Dole, M.

1991-01-01

With the use of plastics in the construction of space satellites which may be exposed in geosynchronous orbit to 100 MGy (10,000 Mrad) of high-energy radiation in 30 years of use, the effect of these radiations on the polymer becomes of practical importance. To understand the effects we consider first various radiation-resistant groups that are incorporated into the polymer and their relative effectiveness in reducing molecular scissions due to the radiation. The location of such groups in the polymer is also discussed. Next the chemical structures of a number of resins such as epoxies, polyimides, etc. are described followed by a detailed account of methods of improving the radiation resistance of plastics by the incorporation of carbon or glass fibers. Finally, the role of oxygen in causing chain scissions and other effects during irradiation which reduce the mechanical strength of the plastics and the fiber resin composites are also considered. (author)

Application of living radical polymerization to the synthesis of resist polymers for radiation lithography

International Nuclear Information System (INIS)

Shimizu, Takashi; Ichikawa, Tsuneki

2005-01-01

Poly(styrene) and poly(methyl acrylate) with benzyl ester of carboxylic acid at the center of the polymer skeletons were synthesized by living radical polymerization for developing a new type of radiation resist with high resistivity to plasma etching and high sensitivity and spatial resolution to ionizing radiations. The initiators were benzyl esters with two functional groups for living radical polymerization on the benzyl and the carboxylic sides. Introduction of benzyl ester to the polymer skeletons changed the polymers from cross-link type to scission type upon γ-irradiation. Irradiation of the polymers resulted in the binary change of the molecular weight, due to dissociative capture of secondary electrons by the benzyl ester, as M n R 1 COOCH(C 6 H 5 )R 2 M n +e - ->M n R 1 COO - + · CH(C 6 H 5 )R 2 M n . The generated polymer fragments were not decomposed by further irradiation, which suggests that the synthesized polymers have high resistivity to plasma etching

Review of radiation processing of natural polymer

International Nuclear Information System (INIS)

Khairul Zaman

2007-01-01

In recent years, natural polymers are being investigated with renewed interest because of their abundant quantity and unique characteristics such as inherent biocompatibility, biodegradability and renewable. It is also known as green polymer. Natural polymers such as carrageen, alginate, chitin/chitosan and starch are traditionally used in food-based industry. But now, the applications of natural polymers are being sought in knowledge-driven areas such as healthcare, agro-technology and industry. Radiation degraded alginates, carrangeenan and chitosan as plant growth promoter and protector have been developed. Radiation degraded chitosan, carraneenan and starch have also been used together with synthetic polymers for hydrogel production to be used for wound dressing, skin moisturization and for biodegradable packaging films and foams. Radiation crosslinking of natural polymer derivatives such as carboxymethyl chitosan, carboxymethyl starch have been successfully developed in Japan and used for various applications such as removal of pollutants, removal of waters from liverstock excrete as well as for bedsores protection mat. (author)

Technical Note: Preliminary investigations into the use of a functionalised polymer to reduce diffusion in Fricke gel dosimeters

Energy Technology Data Exchange (ETDEWEB)

Smith, S. T., E-mail: s164.smith@qut.edu.au; Masters, K.-S.; Hosokawa, K.; Blinco, J. P.; Trapp, J. V. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane 4000 (Australia); Crowe, S. B. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane 4000, Australia and Cancer Care Services, Royal Brisbane and Women’s Hospital, Brisbane 4006 (Australia); Kairn, T. [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane 4000, Australia and Genesis Cancer Care Queensland, Brisbane 4066 (Australia)

2015-12-15

Purpose: A modification of the existing PVA-FX hydrogel has been made to investigate the use of a functionalised polymer in a Fricke gel dosimetry system to decrease Fe{sup 3+} diffusion. Methods: The chelating agent, xylenol orange, was chemically bonded to the gelling agent, polyvinyl alcohol (PVA) to create xylenol orange functionalised PVA (XO-PVA). A gel was created from the XO-PVA (20% w/v) with ferrous sulfate (0.4 mM) and sulfuric acid (50 mM). Results: This resulted in an optical density dose sensitivity of 0.014 Gy{sup −1}, an auto-oxidation rate of 0.0005 h{sup −1}, and a diffusion rate of 0.129 mm{sup 2} h{sup −1}; an 8% reduction compared to the original PVA-FX gel, which in practical terms adds approximately 1 h to the time span between irradiation and accurate read-out. Conclusions: Because this initial method of chemically bonding xylenol orange to polyvinyl alcohol has inherently low conversion, the improvement on existing gel systems is minimal when compared to the drawbacks. More efficient methods of functionalising polyvinyl alcohol with xylenol orange must be developed for this system to gain clinical relevance.

Radiation effects of ion beams on polymers

International Nuclear Information System (INIS)

Tagawa, Seiichi

1993-01-01

Recent progress in the radiation effects of ion beams on polymers are reviewed briefly. Our recent work on the radiation effects of ion beams on polystyrene thin films on silicon wafers and time resolved emission studies on polymers are described. (orig.)

Radiation synthesis and modification of polymers for biomedical applications. Final results of a co-ordinated research project. 1996-2000

CERN Document Server

2002-01-01

Radiation techniques are being used for synthesis of hydrogels, functional polymers, interpenetrating systems, chemical modification of surfaces, immobilization of bioactive materials, synthesis of functional micro- and nanospheres and processing of naturally derived biomaterials. Potential medical applications of these biomaterials include implants, topical dressings, treatment devices and drug delivery systems. Biotechnological applications include diagnostic assays, separation and purification systems, immobilized enzyme and cell bioprocesses and cell culture surfaces. The main objective of the CRP on The use of Radiation Processing to Prepare Biomaterials for Application in Medicine was to co-ordinate the research carried out in the participating countries, to ensure that different research programmes complement each other and the information exchange is available to all. Furthermore, the objective was to expand the use of ionizing radiation in two major areas: synthesis of polymers and gels for medical a...

Effect of thiolated polymers to textural and mucoadhesive properties of vaginal gel formulations prepared with polycarbophil and chitosan.

Science.gov (United States)

Cevher, Erdal; Sensoy, Demet; Taha, Mohamed A M; Araman, Ahmet

2008-01-01

The aim of this study was to design and evaluate of mucoadhesive gel formulations for the vaginal application of clomiphene citrate (CLM) for local treatment of human papilloma virus (HPV) infections. Chitosan (CHI) and polycarbophil (PC) were covalently modified using the thioglycolic acid and L-cysteine, respectively. The formation of thiol conjugates of chitosan (CHI-TG) and polycarbophil (PC-CYS) were confirmed by FT-IR analysis and PC-CYS and CHI-TG were found to have 148.42 +/- 4.16 and 41.17 +/- 2.34 micromol of thiol groups per gram of polymer, respectively. One percent CLM gels were prepared by combination of various concentrations of PC and CHI with thiolated conjugates of these polymers. Hardness, compressibility, elasticity, adhesiveness and cohesiveness of the gels were measured by Texture profile analysis and the vaginal mucoadhesion was investigated by mucoadhesion test. The increasing in the amount of the thiol conjugates was found to enhance the elasticity, cohesiveness, adhesiveness and mucoadhesion of the gel formulations but not their hardness and compressibility when compared to gels prepared using their respective parent formulations. Slower release rate of CLM from gels was achieved when the polymer concentrations were increased in the gel formulations. PC and its thiol conjugate were found to prolong the release of CLM longer than 70 h unlike gel formulations prepared using CHI and its thiol conjugate which were able to release CLM up to 12 h. Stability of CLM was preserved during the 3 month stability analysis under controlled room temperature and accelerated conditions.

Design of Autonomous Gel Actuators

Directory of Open Access Journals (Sweden)

Shuji Hashimoto

2011-01-01

Full Text Available In this paper, we introduce autonomous gel actuators driven by chemical energy. The polymer gels prepared here have cyclic chemical reaction networks. With a cyclic reaction, the polymer gels generate periodical motion. The periodic motion of the gel is produced by the chemical energy of the oscillatory Belouzov-Zhabotinsky (BZ reaction. We have succeeded in making synthetic polymer gel move autonomously like a living organism. This experimental fact represents the great possibility of the chemical robot.

Radiation-crosslinking of shape memory polymers based on poly(vinyl alcohol) in the presence of carbon nanotubes

Science.gov (United States)

Basfar, A. A.; Lotfy, S.

2015-01-01

Shape memory polymers based on poly(vinyl alcohol) (SM-PVA) in the presence of 2-carboxyethyl acrylate oligomers (CEA) and multi-wall carbon nanotubes (MWCNTs) crosslinked by ionizing radiation were investigated. Chemical-crosslinking of PVA by glutaraldehyde in the presence of CEA and MWCNTs was also studied. The swelling and gel fraction of the radiation-crosslinked SM-PVA and chemically crosslinked systems were evaluated. Analysis of the swelling and gel fraction revealed a significant reduction in swelling and an increase in the gel fraction of the material that was chemically crosslinked with glutaraldehyde. The radiation-crosslinked SM-PVA demonstrated 100% gelation at an irradiation dose of 50 kGy. In addition, radiation-crosslinked SM-PVA exhibited good temperature responsive shape-memory behavior. A scanning electron microscopy (SEM) analysis was performed. The thermal properties of radiation-crosslinked SM-PVA were investigated by a thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The ability of the material to return or store energy (E‧), to its ability to lose energy (E″), and the ratio of these effects (Tanδ), which is called damping were examined via DMA. The temperature of Tanδ in the radiation-crosslinked SM-PVA decreased significantly by 6 and 13 °C as a result of the addition of MWCNTs. In addition, the temperature of Tanδ for SM-PVA increased as the irradiation dose increased. These radiation-crosslinked SM-PVA materials show promising shape-memory behavior based on the range of temperatures at which Tanδ appears.

Radiation synthesis and characterisation of the network structure of natural/synthetic double-network superabsorbent polymers

International Nuclear Information System (INIS)

Şen, Murat; Hayrabolulu, Hande

2012-01-01

In this study radiation synthesis and characterisation of the network structure of acrylic acid sodium salt/locust bean gum, (AAcNa/LBG) natural/synthetic double-network super absorbent polymers were investigated. Quartet systems composed of acrylic acid sodium salt/locust bean gum/N,N methylene bis acrylamide/water (AAcNa/LBG/MBAAm/water) were prepared at varying degree of neutralisations (DN) by controlling the DN value of AAc and irradiated with gamma rays at ambient temperature at a very low dose rate. The influences of the DN on the swelling and network properties were examined. It was observed that the DN strongly affected the gelation and super absorption properties of the gels. Molecular weight between crosslinks (M ¯ c ), effective crosslink density (ν e ) and mesh size (ξ) of SAPs were calculated from swelling and shear modules data obtained from compression and oscillatory frequency sweep tests. M ¯ c values obtained from the uniaxial deformation experiments were very close to those obtained from the oscillatory shear experiments excluding the completely neutralised gel system. It was concluded that the uniaxial compression technique could be used for the characterisation of the network structure of a hydrogel as along with the rheological analyses; however, a very precise control of the gel size was also needed. - Highlights: ► Radiation synthesis and characterisation of AAcNa/LBG super absorbent polymers described. ► Influences of the DN on the swelling and network properties were examined. ► Molecular weight between crosslinks and effective crosslink density of SAPs were calculated. ► Suitability of rheology technique for the characterisation of hydrogels were demonstrated.

Evaluation of the radiation-sensitizer/protector and/or antioxidant efficiencies using Fricke and PAG dosimeters

International Nuclear Information System (INIS)

Meesat, Ridthee; Jay-Gerin, Jean-Paul; Khalil, Abdelouahed; Lepage, Martin

2009-01-01

In this study, our aim is to assess the potential of Fricke and polyacrylamide gel (PAG) dosimeters to quantitatively evaluate the efficiency of potential radiation sensitizers/protectors and antioxidants. These compounds are of importance in radiotherapy as well as in disease prevention and promotion of health. The basic principle of the Fricke dosimeter is the radiation-induced oxidation of Fe 2+ to Fe 3+ in an aerated aqueous 0.4 M H 2 SO 4 . The production of ferric ions is most sensitive to the radical species produced in the radiolysis of water. Using this method, we observed that cystamine (one of the best of the known radioprotectors) can prevent oxydation of Fe 2+ from reactive radiolysis species. However, one obvious disadvantage of the Fricke dosimeter is that it operates under highly acidic conditions (pH 0.46), which may degrade biological compounds. In contrast, the pH of the polyacrylamide gel (PAG) dosimeter is almost neutral, such that degradation of compounds is less probable. A change in R 2 -dose sensitivity was observed in the presence of radiosensitizers/radioprotectors and antioxidants. The protective effect of Trolox (a well-known antioxidant) and thiourea (a radioprotector) was readily observed using the PAG dosimeter. Incorporation of iodinated radiation sensitizers such as NaI and an iodine contrast agent led to a quantifiable sensitizer enhancement ratio. These studies suggest that the Fricke and the PAG dosimeters have the potential to evaluate the efficiency of radiation sensitizers/protectors and antioxidants.

Radiation treated propylene polymers

International Nuclear Information System (INIS)

Hoffman, W.A. III; Baum, G.A.

1982-01-01

A method is provided for imparting improved strength and discoloration resistance to a stabilized propylene polymer that is to be exposed to a sterilizing dose of radiation. From 200 to 400 ppm of a phenolic antioxidant containing an isocyanurate group in its molecular structure, and a thiosynergist in an amount at least 6 times the weight of the antioxidant, are incorporated into the polymer before irradiation

Influence of temperature in TL signal induced by gamma radiation in zircon prepared by sol gel via

International Nuclear Information System (INIS)

Salas, P.; Castano, V.M.; Mendoza A, D.; Gonzalez M, P.R.; Rosa C, E. de la

2000-01-01

In this work, it was realized a study of the temperature effects in thermoluminescent signal (Tl) induced by gamma radiation in zircon, which was prepared by the sol gel method. According to the obtained results, the zircon thermically treated at 500 C or over is sensitive to radiation. This sensitivity is increased when the temperature in study is augmented, moreover, the Tl spectra form also is modified with the temperature increment. The samples thermically treated at 750 C or over present a linear response in the dose interval 27 to 165 Gy; therefore, such materials result promissories for dosimetric purposes. (Author)

Dynamic covalent gels assembled from small molecules:from discrete gelators to dynamic covalent polymers

Institute of Scientific and Technical Information of China (English)

Jian-Yong Zhang; Li-Hua Zeng; Juan Feng

2017-01-01

Dynamic covalent chemistry has emerged recently to be a powerful tool to construct functional materials.This article reviews the progress in the research and development of dynamic covalent chemistry in gels assembled from small molecules.First dynamic covalent reactions used in gels are reviewed to understand the dynamic covalent bonding.Afterwards the catalogues of dynamic covalent gels are reviewed according to the nature of gelators and the interactions between gelators.Dynamic covalent bonding can be involved to form low molecular weight gelators.Low molecular weight molecules with multiple functional groups react to form dynamic covalent cross-linked polymers and act as gelators.Two catalogues of gels show different properties arising from their different structures.This review aims to illustrate the structure-property relationships of these dynamic covalent gels.

Sandy soil plantation in semi-arid zones by polyacrylamide gel conditioner prepared by ionizing radiation. Part of a coordinated programme on radiation modified polymers for biomedical and biochemical applications

International Nuclear Information System (INIS)

Azzam, R.A.I.

1983-07-01

Polyacrylamide gel prepared by ionizing radiation was found to be capable of furnishing adequate conditions for sandy-soil plantation in semi-arid zones. The gel can be tailored for any soil texture under various climatic conditions. The sand-gel combination maintains three cycles of complete destruction and reformation without significant changes in erosion index. Water holding capacity and retention at different suctions in treated sand are increased. This increases water use efficiency. Fertilizers use efficiency is also increased to almost three times that of fertile clayey soil

Cycling Performance of Li4Ti5O12 Electrodes in Ionic Liquid-Based Gel Polymer Electrolytes

International Nuclear Information System (INIS)

Kim, Jin Hee; Kim, Dong Won; Kang, Yong Ku

2012-01-01

We investigated the cycling behavior of Li 4 Ti 5 O 12 electrode in a cross-linked gel polymer electrolyte based on non-flammable ionic liquid consisting of 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide and vinylene carbonate. The Li 4 Ti 5 O 12 electrodes in ionic liquid-based gel polymer electrolytes exhibited reversible cycling behavior with good capacity retention. Cycling data and electrochemical impedance spectroscopy analyses revealed that the optimum content of the cross-linking agent necessary to ensure both acceptable initial discharge capacity and good capacity retention was about 8 wt %

Application of living radical polymerization to the synthesis of resist polymers for radiation lithography

Energy Technology Data Exchange (ETDEWEB)

Shimizu, Takashi [Nitto Denko Co. LTD., Shimohozumi 1-1-2, Ibaraki, Osaka 567-8680 (Japan); Ichikawa, Tsuneki [Division of Materials Chemistry, Graduate school of Engineering, Hokkaido University, Sapporo 060-8628 (Japan)]. E-mail: ichikawa@eng.hokudai.ac.jp

2005-07-01

Poly(styrene) and poly(methyl acrylate) with benzyl ester of carboxylic acid at the center of the polymer skeletons were synthesized by living radical polymerization for developing a new type of radiation resist with high resistivity to plasma etching and high sensitivity and spatial resolution to ionizing radiations. The initiators were benzyl esters with two functional groups for living radical polymerization on the benzyl and the carboxylic sides. Introduction of benzyl ester to the polymer skeletons changed the polymers from cross-link type to scission type upon {gamma}-irradiation. Irradiation of the polymers resulted in the binary change of the molecular weight, due to dissociative capture of secondary electrons by the benzyl ester, as M{sub n}R{sub 1}COOCH(C{sub 6}H{sub 5})R{sub 2}M{sub n}+e{sup -}->M{sub n}R{sub 1}COO{sup -}+{sup {center_dot}}CH(C{sub 6}H{sub 5})R{sub 2}M{sub n}. The generated polymer fragments were not decomposed by further irradiation, which suggests that the synthesized polymers have high resistivity to plasma etching.

Gelation Behavior Study of a Resorcinol–Hexamethyleneteramine Crosslinked Polymer Gel for Water Shut-Off Treatment in Low Temperature and High Salinity Reservoirs

Directory of Open Access Journals (Sweden)

Yongpeng Sun

2017-07-01

Full Text Available Mature oilfields usually encounter the problem of high watercut. It is practical to use chemical methods for water-shutoff in production wells, however conventional water-shutoff agents have problems of long gelation time, low gel strength, and poor stability under low temperature and high salinity conditions. In this work a novel polymer gel for low temperature and high salinity reservoirs was developed. This water-shutoff agent had controllable gelation time, adjustable gel strength and good stability performance. The crosslinking process of this polymer gel was studied by rheological experiments. The process could be divided into an induction period, a fast crosslinking period, and a stable period. Its gelation behaviors were investigated in detail. According to the Gel Strength Code (GSC and vacuum breakthrough method, the gel strength was displayed in contour maps. The composition of the polymer gel was optimized to 0.25~0.3% YG100 + 0.6~0.9% resorcinol + 0.2~0.4% hexamethylenetetramine (HMTA + 0.08~0.27% conditioner (oxalic acid. With the concentration increase of the polymer gel and temperature, the decrease of pH, the induction period became shorter and the crosslinking was more efficient, resulting in better stability performance. Various factors of the gelation behavior which have an impact on the crosslinking reaction process were examined. The relationships between each impact factor and the initial crosslinking time were described with mathematical equations.

Enhanced performance of a quasi-solid-state dye-sensitized solar cell with aluminum nitride in its gel polymer electrolyte

KAUST Repository

Huang, Kuan-Chieh

2011-08-01

The effects of incorporation of aluminum nitride (AlN) in the gel polymer electrolyte (GPE) of a quasi-solid-state dye-sensitized solar cell (DSSC) were studied in terms of performance of the cell. The electrolyte, consisting of lithium iodide (LiI), iodine (I2), and 4-tert-butylpyridine (TBP) in 3-methoxypropionitrile (MPN), was solidified with poly(vinyidene fluoride-co-hexafluoro propylene) (PVDF-HFP). The 0.05, 0.1, 0.3, and 0.5 wt% of AlN were added to the electrolyte for this study. XRD analysis showed a reduction of crystallinity in the polymer PVDF-HFP for all the additions of AlN. The DSSC fabricated with a GPE containing 0.1 wt% AlN showed a short-circuit current density (JSC) and power-conversion efficiency (η) of 12.92±0.54 mA/cm2 and 5.27±0.23%, respectively, at 100 mW/cm2 illumination, in contrast to the corresponding values of 11.52±0.21 mA/cm2 and 4.75±0.08% for a cell without AlN. The increases both in JSC and in η of the promoted DSSC are attributed to the higher apparent diffusion coefficient of I- in its electrolyte (3.52×10-6 cm2/s), compared to that in the electrolyte without AlN of a DSSC (2.97×10-6 cm 2/s). At-rest stability of the quasi-solid-state DSSC with 0.1 wt% of AlN was found to decrease hardly by 5% and 7% at room temperature and at 40 °C, respectively, after 1000 h duration. The DSSC with a liquid electrolyte showed a decrease of about 40% at room temperature, while it virtually lost its performance in about 150 h at 40 °C. Explanations are further substantiated by means of electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and by porosity measurements. © 2010 Elsevier B.V.

Radiation effects in polymers for plastic scintillation detectors

International Nuclear Information System (INIS)

Pla-Dalmau, A.; Bross, A.D.; Hurlbut, C.R.; Moser, S.W.

1994-01-01

Recent developments in both scintillating plastic optical fibers and photon detection devices have spawned new applications for plastic scintillator detectors. This renewed attention has encouraged research that addresses the radiation stability of plastic scintillators. The optical quality of the polymer degrades with exposure to ionizing radiation and thus the light yield of the detector decreases. A complete understanding of all the mechanisms contributing to this radiation-induced degradation of the polymer can lead to techniques that will extend the radiation stability of these materials. Various radiation damage studies have been performed under different atmospheres and dose rates. Currently, the use of additives to preserve the optical properties of the polymer matrix under radiation is being investigated. The authors discuss the effect of certain antioxidants, plasticizers, and cross-linking agents on the radiation resilience of plastic scintillators

Transient gels in colloid-polymer mixtures studied with fluorescence confocal scanning laser microscopy

NARCIS (Netherlands)

Verhaegh, N.A.M.; Asnaghi, D.; Lekkerkerker, H.N.W.

1999-01-01

We study the structure and the time evolution of transient gels formed in colloid-polymer mixtures, by means of uorescence Confocal Scanning Laser Microscopy (CSLM). This technique is used in conjunction with novel colloidal silica particles containing a uorescent core. The confocal micrographs

Proton spectroscopic imaging of polyacrylamide gel dosimeters for absolute radiation dosimetry

International Nuclear Information System (INIS)

Murphy, P.S.; Schwarz, A.J.; Leach, M.O.

2000-01-01

Proton spectroscopy has been evaluated as a method for quantifying radiation induced changes in polyacrylamide gel dosimeters. A calibration was first performed using BANG-type gel samples receiving uniform doses of 6 MV photons from 0 to 9 Gy in 1 Gy intervals. The peak integral of the acrylic protons belonging to acrylamide and methylenebisacrylamide normalized to the water signal was plotted against absorbed dose. Response was approximately linear within the range 0-7 Gy. A large gel phantom irradiated with three, coplanar 3x3cm square fields to 5.74 Gy at isocentre was then imaged with an echo-filter technique to map the distribution of monomers directly. The image, normalized to the water signal, was converted into an absolute dose map. At the isocentre the measured dose was 5.69 Gy (SD = 0.09) which was in good agreement with the planned dose. The measured dose distribution elsewhere in the sample shows greater errors. A T 2 derived dose map demonstrated a better relative distribution but gave an overestimate of the dose at isocentre of 18%. The data indicate that MR measurements of monomer concentration can complement T 2 -based measurements and can be used to verify absolute dose. Compared with the more usual T 2 measurements for assessing gel polymerization, monomer concentration analysis is less sensitive to parameters such as gel pH and temperature, which can cause ambiguous relaxation time measurements and erroneous absolute dose calculations. (author)

Radiation processing of natural polymers: The IAEA contribution

Science.gov (United States)

Haji-Saeid, Mohammad; Safrany, Agnes; Sampa, Maria Helena de O.; Ramamoorthy, Natesan

2010-03-01

Radiation processing offers a clean and additive-free method for preparation of value-added novel materials based on renewable, non-toxic, and biodegradable natural polymers. Crosslinked natural polymers can be used as hydrogel wound dressings, face cleaning cosmetic masks, adsorbents of toxins, and non-bedsore mats; while low molecular weight products show antibiotic, antioxidant, and plant-growth promoting properties. Recognizing the potential benefits that radiation technology can offer for processing of natural polymers into useful products, the IAEA implemented a coordinated research project (CRP) on "Development of Radiation-processed products of Natural Polymers for application in Agriculture, Healthcare, Industry and Environment". This CRP was launched at the end of 2007 with participation of 16 MS to help connecting radiation technology and end-users to derive enhanced benefits from these new value-added products of radiation-processed natural materials. In this paper the results of activities in participating MS related to this work will be presented.

Radiation processing of natural polymers: The IAEA contribution

International Nuclear Information System (INIS)

Haji-Saeid, Mohammad; Safrany, Agnes; Sampa, Maria Helena de O.; Ramamoorthy, Natesan

2010-01-01

Radiation processing offers a clean and additive-free method for preparation of value-added novel materials based on renewable, non-toxic, and biodegradable natural polymers. Crosslinked natural polymers can be used as hydrogel wound dressings, face cleaning cosmetic masks, adsorbents of toxins, and non-bedsore mats; while low molecular weight products show antibiotic, antioxidant, and plant-growth promoting properties. Recognizing the potential benefits that radiation technology can offer for processing of natural polymers into useful products, the IAEA implemented a coordinated research project (CRP) on 'Development of Radiation-processed products of Natural Polymers for application in Agriculture, Healthcare, Industry and Environment'. This CRP was launched at the end of 2007 with participation of 16 MS to help connecting radiation technology and end-users to derive enhanced benefits from these new value-added products of radiation-processed natural materials. In this paper the results of activities in participating MS related to this work will be presented.

Compliant gel polymer electrolyte based on poly(methyl acrylate-co-acrylonitrile)/poly(vinyl alcohol) for flexible lithium-ion batteries

International Nuclear Information System (INIS)

Ma, Xianguo; Huang, Xinglan; Gao, Jiandong; Zhang, Shu; Deng, Zhenghua; Suo, Jishuan

2014-01-01

Highlights: •Compliant gel polymer electrolyte based on P(MA-co-AN)/PVA is facilely prepared for flexible lithium-ion batteries. •The compliant gel polymer electrolyte displays high ionic conductivity, self-standing and mechanical flexible. •The compliant gel polymer electrolyte exhibits excellent chemical and electrochemical performances. -- Abstract: In this report, mechanically compliant gel polymer electrolyte (GPE) for flexible lithium-ion batteries is facilely fabricated. The GPE that based on the poly(methyl acrylate-co-acrylonitrile)/poly(vinyl alcohol) (P(MA-co-AN)/PVA) was prepared via emulsion polymerization. Herein, the P(MA-co-AN) copolymer is anticipated to exert beneficial for the bendability of the GPE, as well as swollen with the liquid electrolyte to provide a facile pathway for ion movement. The PVA serves as a stabilizer during the emulsion polymerization and a mechanical framework for the compliant polymer membrane. Performance benefits of the mechanically compliant membrane are elucidated in terms of mechanical behavior, thermostability and ionic conductivity. The GPE is still self-standing and mechanical flexible after swollen with liquid electrolyte. The GPE displays a conductivity of 0.98 mS cm −1 with the uptake electrolyte up to 150% of its own weight at 30 °C, excellent electrochemical stability window (5.2 V vs. Li/Li + ) and favorable interfacial characteristics. When used in flexible lithium-ion batteries, such a GPE demonstrates satisfactory compatibility with LiCoO 2 and graphite electrodes

Effect of the type of radiation on the degradation behavior of polymer matrix composites

International Nuclear Information System (INIS)

Egusa, Shigenori

1992-01-01

Four kinds of polymer matrix composites (filler: E-glass or carbon fiber cloth; matrix; epoxy or polyimide resin) were irradiated with neutrons and 60 Co γ-rays at room temperature or at 5 K. Three-point bend tests were then carried out at 77 K. Comparison of the neutron and γ-ray irradiation effects shows that the radiation sensitivity of the glass/epoxy and glass/polyimide composites is 1.8-2.6 times higher to neutrons than to γ-rays, indicating a higher sensitivity of the epoxy and polyimide matrix resins to recoil protons than to γ-rays. Absorbed dose calculations, on the other hand, show that the spatial distribution of the microscopic energy deposition in polymer matrix composites is inhomogeneous for neutrons, although almost homogeneous for γ-rays. In addition, the neutron irradiation of boron-containing E-glass fiber composites produces additional radiation damage due to a 10 B(n,α) 7 Li reaction in the glass fibers, thus significantly enhancing a decrease in the composite strength. These facts indicate that as far as polymer matrix composites are concerned, the irradiation effects of neutrons will be rather difficult to simulate with different types of radiation such as protons and carbon ions from an ion accelerator. Thus, it may be prudent that such simulation irradiation be carried out mainly for pure resins to be used as matrix in polymer matrix composites. (author)

Analysis of charge transport in gels containing polyoxometallates using methods of different sensitivity to migration.

Science.gov (United States)

Caban, Karolina; Lewera, Adam; Zukowska, Grazyna Z; Kulesza, Pawel J; Stojek, Zbigniew; Jeffrey, Kenneth R

2006-08-04

Two methods have been used for examination of transport of charge in gels soaked with DMF and containing dissolved polyoxometallates. The first method is based on the analysis of both Cottrellian and steady-state currents and therefore is capable of giving the concentration of the electroactive redox centres and their transport (diffusion-type) coefficient. The second method provides the real diffusion coefficients, i.e. transport coefficients free of migrational influence, for both the substrate and the product of the electrode reaction. Several gels based on poly(methyl methacrylate), with charged (addition of 1-acrylamido-2-methyl-2-propanesulphonic acid to the polymerization mixture) and uncharged chains, have been used in the investigation. The ratio obtained for the diffusion coefficient (second method) and transport coefficient (first method) was smaller for the gels containing charged polymer chains than for the gels with uncharged chains. In part these changes could be explained by the contribution of migration to the transport of polyoxomatallates in the gels. However, the impact of the changes in the polymer-channel capacity at the electrode surface while the electrode process proceeds was also considered. These structural changes should affect differently the methods based on different time domains.

Electrolyte transport in neutral polymer gels embedded with charged inclusions

Science.gov (United States)

Hill, Reghan

2005-11-01

Ion permeable membranes are the basis of a variety of molecular separation technologies, including ion exchange, gel electrophoresis and dialysis. This work presents a theoretical model of electrolyte transport in membranes comprised of a continuous polymer gel embedded with charged spherical inclusions, e.g., biological cells and synthetic colloids. The microstructure mimics immobilized cell cultures, where electric fields have been used to promote nutrient transport. Because several important characteristics can, in principle, be carefully controlled, the theory provides a quantitative framework to help tailor the bulk properties for enhanced molecular transport, microfluidic pumping, and physicochemical sensing applications. This talk focuses on the electroosmotic flow driven by weak electric fields and electrolyte concentration gradients. Also of importance is the influence of charge on the effective ion diffusion coefficients, bulk electrical conductivity, and membrane diffusion potential.

Research of radiation firmness of transparent melamine-formaldehyde polymers

International Nuclear Information System (INIS)

Lebedev, V.V.

2007-01-01

Radiation properties of the transparent melamine-formaldehyde polymers offered in quality polymeric basis for making of plastic scintillators are explored in this work. Plastic scintillator is composition, that consists of polymer (polymeric basis) and organic fluorescent addition. Scintillation efficiency and light output are basic properties of plastic scintillators. Firmness to influencing of ionizing radiation is important property of scintillators. From all types of scintillators the plastic are most radiation-proof. Cured melamine-formaldehyde resin and melamine-formaldehyde resin modified by different polyol modifiers was a research object. It is shown that radiation firmness for given types of polymeric material considerably depends on composition of polymer and from technology and temperature condition of its receipt. By the method IR-spectroscopy the structural changes in melamine-formaldehyde polymers under action of irradiation were explored. The maximal falling after the irradiation was marked in intensity of luminescence, which went down to 50% from an initial level. Like the coefficients of admission for all compositions got worse of a to 30-35% level from initial one. Mechanical properties went down on 20-30%. The radiation loss of mass made less than 1% for all polymers. With the increase of temperature of curing firmness rises. Thus, on the basis of the conducted researches radiation firmness for different melamine-formaldehyde polymers is determined and processes what is going on in material under action of radiation are studied. The limited doses of irradiation for each of explored polymers are determined. (authors)

Selectivity of radiation-induced processes in hydrocarbons, related polymers and organized polymer systems

International Nuclear Information System (INIS)

Feldman, V.I.; Sukhov, F.F.; Zezin, A.A.; Orlov, A.Yu.

1999-01-01

Fundamental aspects of the selectivity of radiation-induced events in polymers and polymeric systems were considered: (1) The grounds of selectivity of the primary events were analyzed on the basis of the results of studies of model compounds (molecular aspect). Basic results were obtained for hydrocarbon molecules irradiated in low-temperature matrices. The effects of selective localization of the primary events on the radical formation were examined for several polymers irradiated at low and superlow temperatures (77 and 15 K). A remarkable correlation between the properties of prototype ionized molecules (radical cations) and selectivity of the primary bond rupture in the corresponding polymers were found for polyethylene, polystyrene and some other hydrocarbon polymers. The first direct indication of selective localization of primary events at conformational defects was obtained for oriented high-crystalline polyethylene irradiated at 15 K. The significance of dimeric ring association was proved for the radiation chemistry of polystyrene. Specific mechanisms of low-temperature radiation-induced degradation were also analyzed for polycarbonate and poly(alkylene terephthalates). (2) Specific features of the localization of primary radiation-induced events in microheterogeneous polymeric systems were investigated (microstructural aspect). It was found that the interphase processes played an important role in the radiation chemistry of such systems. The interphase electron migration may result in both positive and negative non-additive effects in the formation of radiolysis products. The effects of component diffusion and chemical reactions on the radiation-induced processes in microheterogeneous polymeric systems were studied with the example of polycarbonate - poly(alkylene terephthalate) blends. (3) The effects of restricted molecular motion on the development of the radiation-chemical processes in polymers were investigated (dynamic aspect). In particular, it

ZnTe Semiconductor-Polymer Gel Composited Electrolyte for Conversion of Solar Energy

Directory of Open Access Journals (Sweden)

Wonchai Promnopas

2014-01-01

Full Text Available Nanostructured cubic p-type ZnTe for dye sensitized solar cells (DSSCs was synthesized from 1 : 1 molar ratio of Zn : Te by 600 W and 900 W microwave plasma for 30 min. In this research, their green emissions were detected at the same wavelengths of 563 nm, the energy gap (Eg at 2.24 eV, and three Raman shifts at 205, 410, and 620 cm−1. The nanocomposited electrolyte of quasisolid state ZnO-DSSCs was in correlation with the increase in the JSC, VOC, fill factor (ff, and efficiency (η by increasing the wt% of ZnTe-GPE (gel polymer electrolyte to an optimum value and decreased afterwards. The optimal ZnO-DSSC performance was achieved for 0.20 wt% ZnTe-GPE with the highest photoelectronic energy conversion efficiency at 174.7% with respect to that of the GPE without doping of p-type ZnTe.

Analysis of polymer foil heaters as infrared radiation sources

International Nuclear Information System (INIS)

Witek, Krzysztof; Piotrowski, Tadeusz; Skwarek, Agata

2012-01-01

Infrared radiation as a heat source is used in many fields. In particular, the positive effect of far-infrared radiation on living organisms has been observed. This paper presents two technological solutions for infrared heater production using polymer-silver and polymer-carbon pastes screenprinted on foil substrates. The purpose of this work was the identification of polymer layers as a specific frequency range IR radiation sources. The characterization of the heaters was determined mainly by measurement of the surface temperature distribution using a thermovision camera and the spectral characteristics were determined using a special measuring system. Basic parameters obtained for both, polymer silver and polymer carbon heaters were similar and were as follows: power rating of 10–12 W/dm 2 , continuous working surface temperature of 80–90 °C, temperature coefficient of resistance (TCR) about +900 ppm/K for polymer-carbon heater and about +2000 ppm/K for polymer-silver, maximum radiation intensity in the wavelength range of 6–14 μm with top intensity at 8.5 μm and heating time about 20 min. For comparison purposes, commercial panel heater was tested. The results show that the characteristics of infrared polymer heaters are similar to the characteristics of the commercial heater, so they can be taken into consideration as the alternative infrared radiation sources.

Expected and unexpected achievements and trends in radiation processing of polymers

International Nuclear Information System (INIS)

Czvikovszky, T.

2002-01-01

Complete text of publication follows. The last four decades produced exponential development in the polymer processing. Radiation processing yielded a similar pathway of development in the beginning, mostly in the radiation crosslinking of polymers and in the radiation sterilization of polymer products. Some expectations on several related fields such as radiation grafting, surface coating of polymer films, etc., have not really been fulfilled. There are some unexpected results in the developments of the radiation chemistry of polymers utilized well in the polymer processing today. The most dynamical developments of the microelectronics in our days is based on the efficient utilization of radiation-crosslinkable negative photoresist polymers and the radiation degradable positive photoresist polymers. Rapid prototyping and rapid tooling are indispensable methods in the continuously renewing manufacturing technologies of metal and plastic parts for almost all the industrial branches. Rapid prototyping allows to make a real polymeric part of an automobile or of a mobile phone directly from the computer assisted design draft on the monitor, without any human interference. The selective laser lithography is using radiation-reactive oligomers for this purpose. Polymer composite manufacturing is also profited in many ways from the experiences of radiation technology. High-tech composites of advanced fibers such as graphite, Kevlar, HOPE and other ones require well-engineered interface between reinforcing fiber and matrix. This interface is the key factor, especially in the case of injection-moldable composites of short fibers and thermoplastics, and this interface can greatly be improved through ionizing radiation. Our recent results in this field confirmed substantial benefits in the case of carbon fiber reinforced structures and in the case of natural fiber reinforced composites as well. Compatibilization through radiation-reactive monomers and oligomers is attacking

In situ immobilization on the silica gel surface and adsorption capacity of polymer-based azobenzene on toxic metal ions

Science.gov (United States)

Savchenko, Irina; Yanovska, Elina; Sternik, Dariusz; Kychkyruk, Olga; Ol'khovik, Lidiya; Polonska, Yana

2018-03-01

In situ immobilization of poly[(4-methacryloyloxy-(4'-carboxy)azobenzene] on silica gel surface has been performed by radical polymerization of monomer. The fact of polymer immobilization is confirmed by IR spectroscopy. TG and DSC-MS analysis showed that the mass of the immobilized polymer was 10.61%. The SEM-microphotograph-synthesized composite analysis showed that the immobilized polymer on the silica gel surface is placed in the form of fibers. It has been found that the synthesized composite exhibits the sorption ability in terms of microquantities of Cu(II), Cd(II), Pb(II), Mn(II) and Fe(III) ions in a neutral aqueous medium. The quantitative sorption of microquantities of Pb(II) and Fe(III) ions has been recorded. It has been found that immobilization of the silica gel surface leads to an increase in its sorption capacitance for Fe(III), Cu(II) and Pb(II) ions by half.

Recording of radiation-induced optical density changes in doped agarose gels with a CCD camera

International Nuclear Information System (INIS)

Tarte, B.J.; Jardine, P.A.; Van Doorn, T.

1996-01-01

Full text: Spatially resolved dose measurement with iron-doped agarose gels is continuing to be investigated for applications in radiotherapy dosimetry. It has previously been proposed to use optical methods, rather than MRI, for dose measurement with such gels and this has been investigated using a spectrophotometer (Appleby A and Leghrouz A, Med Phys, 18:309-312, 1991). We have previously studied the use of a pencil beam laser for such optical density measurement of gels and are currently investigating charge-coupled devices (CCD) camera imaging for the same purpose but with the advantages of higher data acquisition rates and potentially greater spatial resolution. The gels used in these studies were poured, irradiated and optically analysed in Perspex casts providing gel sections 1 cm thick and up to 20 cm x 30 cm in dimension. The gels were also infused with a metal indicator dye (xylenol orange) to render the radiation induced oxidation of the iron in the gel sensitive to optical radiation, specifically in the green spectral region. Data acquisition with the CCD camera involved illumination of the irradiated gel section with a diffuse white light source, with the light from the plane of the gel section focussed to the CCD array with a manual zoom lens. The light was also filtered with a green colour glass filter to maximise the contrast between unirradiated and irradiated gels. The CCD camera (EG and G Reticon MC4013) featured a 1024 x 1024 pixel array and was interfaced to a PC via a frame grabber acquisition board with 8 bit resolution. The performance of the gel dosimeter was appraised in mapping of physical and dynamic wedged 6 MV X-ray fields. The results from the CCD camera detection system were compared with both ionisation chamber data and laser based optical density measurements of the gels. Cross beam profiles were extracted from each measurement system at a particular depth (eg. 2.3 cm for the physical wedge field) for direct comparison. A

Control of Polymer Nanostructure and Functionality via Radiation Grafting

International Nuclear Information System (INIS)

Palmese, G.R.

2006-01-01

Radiation grafting provides a useful means for controlling polymer structure and performance. Particularly, it is appropriate for combining materials with distinct thermodynamic characteristics chemically at interfaces. Therefore polymeric materials that generally will not mix - i.e hydrophilic and hydrophobic polymers - can be combined efficiently using radiation based methods. This is of particular importance when attempting to form polymer-polymer nanocomposites where the thermodynamic penalty associated with high specific interfacial surface area is very large. Generally, the combination at small scales of such distinct materials is appropriate when specific functionality is desired while maintaining structural performance characteristics. In such cases the hydrophilic polymer lends functional characteristics such as ionic conductivity, self-healing, and actuation, while the hydrophobic polymer component provides structural stability. In this communication a summary of our recent work concerning the use of radiation grafting for the synthesis of nanostructured functional materials is given. Examples to be discussed include toughing of polymeric systems, the synthesis polymeric and inorganic nanotubes, and the design of permeation selective membranes. These examples will be used to demonstrate the effectiveness of radiation grafting techniques for controlling polymer properties and small-scale structure

Measurement of relative dose distributions in stereotactic radiosurgery by the polymer-gel dosimeter

Czech Academy of Sciences Publication Activity Database

Novotný ml., J.; Spěváček, V.; Hrbáček, J.; Judas, L.; Novotný, J.; Dvořák, P.; Tlacháčová, D.; Schmitt, M.; Tintěra, J.; Vymazal, J.; Čechák, T.; Michálek, Jiří; Přádný, Martin; Liščák, R.

2004-01-01

Roč. 5, - (2004), s. 225-235 ISSN 1024-2651. [International Stereotactic Radiosurgery Society Meeting /6./. Kyoto, 22.06.2003-26.06.2003] R&D Projects: GA MZd NC7460 Institutional research plan: CEZ:AV0Z4050913 Keywords : stereotactic radiosurgery * polymer-gel dosimeter Subject RIV: FD - Oncology ; Hematology

Integration of molecular machines into supramolecular materials: actuation between equilibrium polymers and crystal-like gels.

Science.gov (United States)

Mariani, Giacomo; Goujon, Antoine; Moulin, Emilie; Rawiso, Michel; Giuseppone, Nicolas; Buhler, Eric

2017-11-30

In this article, the dynamic structure of complex supramolecular polymers composed of bistable [c2]daisy chain rotaxanes as molecular machines that are linked by ureidopyrimidinones (Upy) as recognition moieties was studied. pH actuation of the integrated mechanically active rotaxanes controls the contraction/extension of the polymer chains as well as their physical reticulation. Small-angle neutron and X-ray scattering were used to study in-depth the nanostructure of the contracted and extended polymer aggregates in toluene solution. The supramolecular polymers comprising contracted nanomachines were found to be equilibrium polymers with a mass that is concentration dependent in dilute and semidilute regimes. Surprisingly, the extended polymers form a gel network with a crystal-like internal structure that is independent of concentration and reminiscent of a pearl-necklace network.

Study on radiation-induced polymerization of vinyl monomers adsorbed on inorganic substances. II. Radiation-induced polymerization of methyl methacrylate adsorbed on several inorganic substances

International Nuclear Information System (INIS)

Fukano, K.; Kageyama, E.

1975-01-01

The radiation-induced polymerization of methyl methacrylate (MMA) adsorbed on such inorganic substances as silica gel, white carbon, silicic acid anhydride, zeolite, and activated alumina was carried out to compare with the case of styrene. The rate of radiation-induced polymerization adsorbed on inorganic substances was high compared with that of radiation-induced bulk state polymerization, as was the case with styrene. Inorganic substrates which contain aluminum as a component element are more likely to be grafted than those which consist of SiO 2 alone, as with styrene. The molecular weight distribution of unextractable polymer and extractable polymer differs, depending on the type of inorganic substance. Experiments by a preirradiation method were carried out in case of silica gel, white carbon, and silicic acid anhydride. GPC spectra of the polymer obtained were different from those of polymer formed by the simultaneous irradiation method. It appears that all the unextractable polymer is grafted to the inorganic surface with chemical bond

pH- and ion-sensitive polymers for drug delivery

Science.gov (United States)

Yoshida, Takayuki; Lai, Tsz Chung; Kwon, Glen S; Sako, Kazuhiro

2013-01-01

Introduction Drug delivery systems (DDSs) are important for effective, safe, and convenient administration of drugs. pH- and ion-responsive polymers have been widely employed in DDS for site-specific drug release due to their abilities to exploit specific pH- or ion-gradients in the human body. Areas covered Having pH-sensitivity, cationic polymers can mask the taste of drugs and release drugs in the stomach by responding to gastric low pH. Anionic polymers responsive to intestinal high pH are used for preventing gastric degradation of drug, colon drug delivery and achieving high bioavailability of weak basic drugs. Tumor-targeted DDSs have been developed based on polymers with imidazole groups or poly(β-amino ester) responsive to tumoral low pH. Polymers with pH-sensitive chemical linkages, such as hydrazone, acetal, ortho ester and vinyl ester, pH-sensitive cell-penetrating peptides and cationic polymers undergoing pH-dependent protonation have been studied to utilize the pH gradient along the endocytic pathway for intracellular drug delivery. As ion-sensitive polymers, ion-exchange resins are frequently used for taste-masking, counterion-responsive drug release and sustained drug release. Polymers responding to ions in the saliva and gastrointestinal fluids are also used for controlled drug release in oral drug formulations. Expert opinion Stimuli-responsive DDSs are important for achieving site-specific and controlled drug release; however, intraindividual, interindividual and intercellular variations of pH should be considered when designing DDSs or drug products. Combination of polymers and other components, and deeper understanding of human physiology are important for development of pH- and ion-sensitive polymeric DDS products for patients. PMID:23930949

pH- and ion-sensitive polymers for drug delivery.

Science.gov (United States)

Yoshida, Takayuki; Lai, Tsz Chung; Kwon, Glen S; Sako, Kazuhiro

2013-11-01

Drug delivery systems (DDSs) are important for effective, safe, and convenient administration of drugs. pH- and ion-responsive polymers have been widely employed in DDS for site-specific drug release due to their abilities to exploit specific pH- or ion-gradients in the human body. Having pH-sensitivity, cationic polymers can mask the taste of drugs and release drugs in the stomach by responding to gastric low pH. Anionic polymers responsive to intestinal high pH are used for preventing gastric degradation of drug, colon drug delivery and achieving high bioavailability of weak basic drugs. Tumor-targeted DDSs have been developed based on polymers with imidazole groups or poly(β-amino ester) responsive to tumoral low pH. Polymers with pH-sensitive chemical linkages, such as hydrazone, acetal, ortho ester and vinyl ester, pH-sensitive cell-penetrating peptides and cationic polymers undergoing pH-dependent protonation have been studied to utilize the pH gradient along the endocytic pathway for intracellular drug delivery. As ion-sensitive polymers, ion-exchange resins are frequently used for taste-masking, counterion-responsive drug release and sustained drug release. Polymers responding to ions in the saliva and gastrointestinal fluids are also used for controlled drug release in oral drug formulations. Stimuli-responsive DDSs are important for achieving site-specific and controlled drug release; however, intraindividual, interindividual and intercellular variations of pH should be considered when designing DDSs or drug products. Combination of polymers and other components, and deeper understanding of human physiology are important for development of pH- and ion-sensitive polymeric DDS products for patients.

Radiation modification of polymers: fundamentals and applications

International Nuclear Information System (INIS)

Clough, R.L.

2003-01-01

When polymers were first exposed to ionizing radiation some 50 years ago, the resultant changes were found to be complex and relatively non-selective. Most importantly, irradiation was seen to give a mix of bond forming and bond breaking processes, and different polymer types were classified into two groups according to which process predominated. For polymers in the 'crosslinking' category, large industrial applications emerged within the first two decades of the initiation of this field, including heat shrink products, high performance wire insulation and tire manufacturing. There has been continuing work toward development of a wide range of new applications based on polymers and radiation, and this field remains quite active today. One approach to finding new commercial processes has been to take advantage of a variety of different radiation-induced phenomena (for example, uses for chain scission have emerged for enhancing the processing properties of various bulk polymers, for recycling of rubber, and for microlithography and LIGA). Another approach has taken advantage of progress in the science of radiation chemistry, by employing our increasing knowledge to enhance and/or reduce competing processes through the use of additives, the design of specialized resins, controlling gaseous atmospheres, varying processing conditions such as temperature, post-irradiation treatments, etc. This presentation will survey some of the exciting developments in polymer radiation processing, and will point out some of the underlying phenomena that are being manipulated to further their success. We will finish by describing progress on fundamental isotope-labeling studies of one longstanding mechanistic complexity, oxidation chemistry, which is critical in many radiation processing applications, such as retarding post-irradiation degradation problems, enhancing chain scission where desired, altering surface polarity, and providing a useful pretreatment in grafting schemes

Effects of TiO2 and TiC Nanofillers on the Performance of Dye Sensitized Solar Cells Based on the Polymer Gel Electrolyte of a Cobalt Redox System.

Science.gov (United States)

Venkatesan, Shanmuganathan; Liu, I-Ping; Chen, Li-Tung; Hou, Yi-Chen; Li, Chiao-Wei; Lee, Yuh-Lang

2016-09-21

Polymer gel electrolytes (PGEs) of cobalt redox system are prepared for dye sensitized solar cell (DSSC) applications. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is used as a gelator of an acetonitrile (ACN) liquid electrolyte containing tris(2,2'-bipyridine)cobalt(II/III) redox couple. Titanium dioxide (TiO2) and titanium carbide (TiC) nanoparticles are utilized as nanofillers (NFs) of this PGE, and the effects of the two NFs on the conductivity of the PGEs, charge-transfer resistances at the electrode/PGE interface, and the performance of the gel-state DSSCs are studied and compared. The results show that the presence of TiC NFs significantly increases the conductivity of the PGE and decreases the charge-transfer resistance at the Pt counter-electrode (CE)/PGE interface. Therefore, the gel-state DSSC utilizing TiC NFs can achieve a conversion efficiency (6.29%) comparable to its liquid counterpart (6.30%), and, furthermore, the cell efficiency can retain 94% of its initial value after a 1000 h stability test at 50 °C. On the contrary, introduction of TiO2 NFs in the PGE causes a decrease of cell performances. It shows that the presence of TiO2 NFs increases the charge-transfer resistance at the Pt CE/PGE interface, induces the charge recombination at the photoanode/PGE interface, and, furthermore, causes a dye desorption in a long-term-stability test. These results are different from those reported for the iodide redox system and are ascribed to a specific attractive interaction between TiO2 and cobalt redox ions.

Investigation of the Spatial Resolution of MR-Based Polymer Gel Dosimetry versus Film Densitometry using Dose Modulation Transfer Function

Directory of Open Access Journals (Sweden)

Reza Moghadam-Drodkhani

2011-03-01

Full Text Available Introduction: The conventional methods of dosimetry are not capable of dosimetry in such a small volume of less than one cubic millimeter. Although the polymer gel dosimetry method based on magnetic resonance imaging (MRI could achieve three dimensional dosimetry with high resolution, a spatial resolution evaluation based on gel dose modulation transfer function has not been investigated yet. Therefore, in this study, the spatial resolution of two systems of film densitometry and polymer gel dosimetry based on MRI has been evaluated by using the dose modulation transfer function (DMTF.   Material and Methods: Kodak therapy verification films and MAGICA polymer gel samples were positioned below a brass absorption grid with different periodic slices (a/2= 280, 525, 1125 μm, which was placed in a water bath container to avoid regions of dose build-up just below the absorption grid and then irradiated with Cobalt-60 photons on a Theratron external-beam treatment unit. Dose variation under the brass grid was determined using a calibration curve, while transverse relaxation time (T2 as the selective parameter in a dose image based on multiple echo MRI with 1.5 Tesla GE Signa Echo Speed system (FOV=10 cm, matrix size=512 ×512, pixel size =0.199×0.199 mm2, TE = 20, 40, 60, 80 ms, TR=4200 ms, NEX = 4, slice thickness=2 mm, gap=1 mm was calculated. DMTF from the modulation depths of T2 and variation in film optical density after calibration would be achieved. The results of polymer gel were compared with film. Results: After deriving the dose distribution profile under the absorption grid, minima and maxima at the smallest period of a = 560 μm could scarcely be resolved, but the modulations due to a=2250 μm and a = 1050 μm grids could be discerned. The modulation depth for a=2250 μm grid was set to 100% and the other modulations were subsequently referred to this maximum modulation. For film densitometry at a = 1050 μm, the modulation depth was

Process for radiation cocrosslinking water soluble polymers and products thereof

International Nuclear Information System (INIS)

Assarsson, P.G.; King, P.A.

1976-01-01

Poly(ethylene oxide) and at least one other water soluble polymer are conveniently cocrosslinked by exposing aqueous systems of the polymers to high energy irradiation. The resulting products are insoluble hydrophilic gels which can contain or when dried absorb large quantities of aqueous fluids and hence are useful as absorbing media for disposable absorbent articles, agricultural applications and the like

Polymers and electromagnetic radiation fundamentals and practical applications

CERN Document Server

Schnabel, Wolfram

2014-01-01

This first book to cover the interaction of polymers with radiation from the entire electromagnetic spectrum adopts a multidisciplinary approach to bridge polymer chemistry and physics, photochemistry, photophysics and materials science. The text is equally unique in its scope, devoting equal amounts of attention to the three aspects of synthesis, characterization, and applications. The first part deals with the interaction of polymers with non-ionizing radiation in the frequency-range from sub-terahertz via infrared radiation to visible and ultraviolet light, while the second covers interaction with ionizing radiation from the extreme ultraviolet to X-ray photons. The result is a systematic overview of how both types of radiation can be used for different polymerization approaches, spectroscopy methods and lithography techniques. Authored by a world-renowned researcher and teacher with over 40 years of experience in the field, this is a highly practical and authoritative guide.

Radiation induced estane polymer crosslinking

International Nuclear Information System (INIS)

Fletcher, M.; Foster, P.

1997-01-01

The exposure of polymeric materials to radiation has been known to induce the effects of crosslinking and degradation. The crosslinking phenomena comes about when two long chain polymers become linked together by a primary bond that extends the chain and increases the viscosity, molecular weight and the elastic modules of the polymer. This process has been observed in relatively short periods of time with fairly high doses of radiation, on the order of several megarads/hour. This paper address low dose exposure over long periods of time to determine what the radiation effects are on the polymeric binder material in PBX 9501. An experimental sample of binder material without explosives will be placed into a thermal and radiation field produced from a W-48 put mod 0. Another sample will be placed in a thermal environment without the radiation. The following is the test plan that was submitted to the Pantex process. The data presented here will be from the first few weeks of exposure and this test will be continued over the next few years. Subsequent data will hopefully be presented in the next compatibility and aging conference

BEAM applications to polymer materials

International Nuclear Information System (INIS)

Tagawa, Seiichi

1994-01-01

Recently papers about beam applications to polymers have been increasing rapidly both in the fundamental and applied fields. Fairly large number of papers have been published in the fundamental aspects of radiation effects of beam applications to polymers such as pulse radiolysis and high density electronic excitation effects. A number of papers have been published in the more applied aspects of beam applications to polymers such as radiation processing and curing. The present paper describes recent beam applications to polymers. 1. Radiation Effects on Polymers; Radiation effects on polymers have been studied for more than 40 years. Most of work on radiation effects on polymers has been carried out by using high energy photon (gamma-ray) and electron beams, since polymers are sensitive to any kinds of ionizing radiation. Even non-ionizing radiation such as ultraviolet and visible light excites electronic excited states of polymers and then photo-chemical reactions of polymers are induced from the electronic excited states. Studies on radiation effects of other ionizing radiation on polymers have not been so popular for a long time. Recently application of new radiation such as ion beams to polymers have been worthy of remark in fields of advanced science and technology, since new radiation beams induce different radiation effects from those induced by high energy gamma-rays and electrons. 2. Beam Applications of Polymers; Recent progress in beam applications to polymers such as radiation processing and curing, x-ray and electron beam microlithography, and applications of new beams such as ion beams to polymers has been reviewed. (author)

Development of advanced natural polymer using radiation technology

International Nuclear Information System (INIS)

Kang, Phil Hyun; Nho, Young Chang; Jeon, Jun Pyo

2012-01-01

This project was performed to develop the environment-friendly and higher value-added materials using natural polymers derivatives from biotic-resources by radiation technology. To study for structural change of natural polymer by radiation, the effect of electron beam and Gamma ray into four kinds of plants such as Kenaf core, kenaf bast, ock and cornhusk was investigated. As results of analysis about structural change of natural polymer by radiation, efficiently separating process of Lignin was developed by improved decomposition of Lignin with increasing power of radiation. Environ-friendly separating process of Cellulose and Lignin using radiation and water-cook was developed without toxically chemical treatment. Papers were fabricated by cellulose and tensile strength of pulp fabricated by radiation was invested properties of pulp depending on power of radiation. High purity cellulose was fabricated by reduced chemical ratio between hemi-cellulose and Lignin with control of radiative power. Manufacturing process of natural paper highly containing cellulose content was developed using efficient separation of cellulose from ock tree, kenaf core and kenaf bast through radiation technique. Cellulose fiber was fabricated using separated cellulose by radiation through the drying and wetting spinning with methanol and water. Also nano-fiber with Lignin was made by electro-spinning with different ratio between PAN and Lignin. Effect of thermal treatment and carbonization of fabricated nano-fiber was invested. Carbon fiber with Lignin was applied to high value-added a secondary battery used as a cathode in half cell type. The secondary battery with carbon fiber with Lignin used as a cathode showed very efficient performance, which revealed capacity-preservation with 100% during 100 cycles. This project could significantly contribute to national competitiveness with radiation technology and Low-carbon and green-growth industrial technology, based on securement of

Three dimensional measurement of dose distributions produced by a robot-mounted linac using magnetic resonance imaging of bang polymer gel dosimeters

International Nuclear Information System (INIS)

Wong, S.P.; Garwood, D.P.; Clarke, G.D.; McColl, R.W.; Maryanski, M.J.; Gore, J.C.

1996-01-01

Purpose/Objective: A novel image-guided robotic radiosurgical system, capable of irradiating 102 non-coplanar nodes in 3 π geometry, produces complex dose distributions which are difficult or impractical to measure with conventional dosimetry instrumentation. The recently developed BANG polymer gel dosimetry system provides accurate, high resolution and three dimensional dose distributions data and is ideally suited for the task described above. In this study, the polymer gels were used for imaging the dose distributions produced by this extremely flexible radiosurgical system. Materials and Methods: The dosimeter materials consist of 2-liter BANG polymer gels in spherical, clear glass flasks, closed with ground glass stoppers, with glass rods extending to the center of the gel that serve as a target for the frameless robotic radiosurgery. A compact 6 MV x-band linac (285 lbs) is mounted and maneuvered by a 6 degree-of-freedom robotic arm. The gels were irradiated using a 25 mm circular insert. A total of 10 Gy was delivered at isocenter at a dose rate of 300 cGy/min using all of the available 102 nodes. The gels were then imaged by MRI(GE Signa) at 1.5 T, using a series of Hahn spin echoes of TR = 3s, TE = 20,100,200,400 ms. Transverse relaxation rate (R 2 ) maps were constructed from those multiple images, using the non-linear least-squares Lavenberg-Marquardt algorithm and a data analysis and display program 'DoseMap' which was written using the scientific computational program MATLAB. R 2 maps were converted to dose maps using an R 2 -to-dose calibration curve. Dose maps and isodose curves were then compared with corresponding data from the treatment planning computer software. Results: The dose dependence of the NMR transverse relaxation rate, R 2 , is reproducible (less than 2 % variation) and is linear up to about 10 Gy, with a slope of 0.25 s -1 Gy -1 at 1.5 Tesla. Isodose curves in three orthogonal (axial, sagittal and coronal) planes show excellent

Obtention of gelatin biopolymers by ionizing radiation

International Nuclear Information System (INIS)

Takinami, Patricia Yoko Inamura

2014-01-01

The gelatin (Gel) is a biocompatible and biodegradable biopolymer, which naturally forms semi-solid colloids or hydrogels in aqueous solutions. As a hydrophilic polymer, the Gel has structural and physico-mechanical properties that distinguish it from synthetic hydrophilic polymers. The study of these properties led to the development of the present work. Thus, Gel-based films and hydrogels were developed using ionizing radiation technology by different techniques: irradiation with 60 Co, electron beam (EB) and/or pulsed EB. The Gel based-films enriched with different additives, such as glycerol (GLY), polyvinyl alcohol (PVA), butylated hydroxytoluene (BHT), acrylamide and/or vegetal fiber, were irradiated with doses from 10 to 60 kGy, depending on the additive; some parameters like mechanical properties, color, and water absorption were analyzed. In the radio-induced synthesis of GEL nanohydrogels, polyethylene glycol (PEG) and the mixture (MIX) of additives, PEG and GEL, the size, molar mass and surface morphology of the nanohydrogels were analyzed. There was a significant increase of gel fraction with increase of the radiation dose for the GEL/fiber samples. The GEL based-films with 10% PVA irradiated at 20 kGy showed the highest puncture strength. The addition of antioxidant BHT affected on some GEL based-films properties on applied conditions. Regarding the nanohydrogels, there was a decrease of hydrodynamic radius of MIX irradiated with 60 Co from 68 ± 25 nm (2 kGy) to 35 ± 4 nm (5 kGy). The radiation proved to be a convenient tool in the modification of polymeric materials for both, GEL films and hydrogels. (author)

Radiation-induced DNA damage and repair in radiosensitive and radioresistant human tumour cells measured by field inversion gel electrophoresis

International Nuclear Information System (INIS)

Smeets, M.F.M.A.; Mooren, E.H.M.; Begg, A.C.

1993-01-01

Radiation-induced DNA damage induction and repair was measured in two human squamous carcinoma cell lines with differing radiosensitivities. Experiments were carried out with field inversion gel electrophoresis (FIGE), adapted to measure DNA double strand break (DSB) induction and repair in unlabelled cells. The sensitivity of the method was increased by introducing a hybridization membrane into the agarose gel. Damaged DNA accumulated on one spot on the membrane resulting in high local concentrations. This DNA was quantified using radioactively-labelled total human DNA as a probe. Radiosensitivity differences at physiological temperatures could not be explained by differences in either induction or repair of DNA damage as measured by pulsed field gel electrophoresis. (author)

Research and Application of Radiation Processed Polymers to Enhance Oil Recovery in Petroleum Industry - Current Status and Prospects

International Nuclear Information System (INIS)

Le Hai; Nguyen Trong Hoanh Phong; Le Van Toan; Nguyen Ly Lan; Nguyen Tan Man; Le Dinh Lang; Nguyen Van Toan; Pham Anh Tuan

2011-01-01

The preparation of polymers for enhanced oil recovery has been carried out by radiation copolymerization method involving two monomers of acrylamide and N-vinyl-2- pyrrolidone, and N-methylpyrrolidone used as an anti-gel agent. The properties and oil recovery efficiency of polymer solution was discussed. The studied polymer dissolved in water and in saline water. They have non-precipitating behavior in hard brines at high temperature (>120 o C) and their viscosity decreased 20% after heating 30 days at 120 o C. Evaluation of oil recovery efficiency has been carried out at Laboratory model of reservoir of oil wells were submerged, the obtained results shown that the recovery yield of oil enhanced higher than 10% in the reservoir temperature and pressure conditions. The experimental results also shown that studied polymer products are applying in effect for submerged oil wells. These studied polymers have been being planned for application in pilot scale on the White Tiger oil field one of the big oil fields in this country. (author)

Development and manufacture of printable next-generation gel polymer ionic liquid electrolyte for Zn/MnO2 batteries

International Nuclear Information System (INIS)

Winslow, R; Wang, Z; Wright, P; Wu, C H; Kim, B; Evans, J; Keif, M

2013-01-01

While much energy storage research focuses on the performance of individual components, such as the electrolyte or a single electrode, few investigate the electrochemical system as a whole. This research reports on the design, composition, and performance of a Zn/MnO 2 battery as affected by the manufacturing method and next-generation gel polymer electrolyte composed of the ionic liquid [BMIM][Otf], ZnOtf salt, and PVDF-HFP polymer binder. Materials and manufacturing tests are discussed with a focus on water concentration, surface features as produced by printing processes, and the effect of including a gel polymer phase. Cells produced for this research generated open circuit voltages from 1.0 to 1.3 V. A dry [BMIM][Otf] electrolyte was found to have 87.3 ppm of H 2 O, while an electrolyte produced in ambient conditions contained 12400 ppm of H 2 O. Cells produced in a dry, Ar environment had an average discharge capacity of 0.0137 mAh/cm 2 , while one produced in an ambient environment exhibited a discharge capacity at 0.05 mAh/cm 2 . Surface features varied significantly by printing method, where a doctor blade produced the most consistent features. The preliminary results herein suggest that water, surface roughness, and the gel polymer play important roles in affecting the performance of printed energy storage

Development and manufacture of printable next-generation gel polymer ionic liquid electrolyte for Zn/MnO2 batteries

Science.gov (United States)

Winslow, R.; Wu, C. H.; Wang, Z.; Kim, B.; Keif, M.; Evans, J.; Wright, P.

2013-12-01

While much energy storage research focuses on the performance of individual components, such as the electrolyte or a single electrode, few investigate the electrochemical system as a whole. This research reports on the design, composition, and performance of a Zn/MnO2 battery as affected by the manufacturing method and next-generation gel polymer electrolyte composed of the ionic liquid [BMIM][Otf], ZnOtf salt, and PVDF-HFP polymer binder. Materials and manufacturing tests are discussed with a focus on water concentration, surface features as produced by printing processes, and the effect of including a gel polymer phase. Cells produced for this research generated open circuit voltages from 1.0 to 1.3 V. A dry [BMIM][Otf] electrolyte was found to have 87.3 ppm of H2O, while an electrolyte produced in ambient conditions contained 12400 ppm of H2O. Cells produced in a dry, Ar environment had an average discharge capacity of 0.0137 mAh/cm2, while one produced in an ambient environment exhibited a discharge capacity at 0.05 mAh/cm2. Surface features varied significantly by printing method, where a doctor blade produced the most consistent features. The preliminary results herein suggest that water, surface roughness, and the gel polymer play important roles in affecting the performance of printed energy storage.

Swimming micro-robot powered by stimuli-sensitive gel

Science.gov (United States)

Masoud, Hassan; Alexeev, Alexander

2012-11-01

Using three-dimensional computer simulations, we design a simple maneuverable micro-swimmer that can self-propel and navigate in highly viscous (low Reynolds-number) environments. Our simple swimmer consists of a cubic gel body which periodically changes volume in response to external stimuli, two rigid rectangular flaps attached to the opposite sides of the gel body, and a flexible steering flap at the front end of the swimmer. The stimuli-sensitive body undergoes periodic expansions (swelling) and contractions (deswelling) leading to a time-irreversible beating motion of the propulsive flaps that propel the micro-swimmer. Thus, the responsive gel body acts as an ``engine'' actuating the motion of the swimmer. We examine how the swimming speed depends on the gel and flap properties. We also probe how the swimmer trajectory can be changed using a responsive steering flap whose curvature is controlled by an external stimulus. We show that the turning occurs due to steering flap bending and periodic beating. Furthermore, our simulations reveal that the turning direction can be regulated by changing the intensity of external stimulus.

Electrochemical sensor based on molecularly imprinted polymer film via sol-gel technology and multi-walled carbon nanotubes-chitosan functional layer for sensitive determination of quinoxaline-2-carboxylic acid.

Science.gov (United States)

Yang, Yukun; Fang, Guozhen; Liu, Guiyang; Pan, Mingfei; Wang, Xiaomin; Kong, Lingjie; He, Xinlei; Wang, Shuo

2013-09-15

Quinoxaline-2-carboxylic acid (QCA) is difficult to measure since only trace levels are present in commercial meat products. In this study, a rapid, sensitive and selective molecularly imprinted electrochemical sensor for QCA determination was successfully constructed by combination of a novel modified glassy carbon electrode (GCE) and differential pulse voltammetry (DPV). The GCE was fabricated via stepwise modification of multi-walled carbon nanotubes (MWNTs)-chitosan (CS) functional composite and a sol-gel molecularly imprinted polymer (MIP) film on the surface. MWNTs-CS composite was used to enhance the electron transfer rate and expand electrode surface area, and consequently amplify QCA reduction electrochemical response. The imprinted mechanism and experimental parameters affecting the performance of MIP film were discussed in detail. The resulting MIP/sol-gel/MWNTs-CS/GCE was characterized using various electrochemical methods involving cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and DPV. The sensor using MIP/sol-gel/MWNTs-CS/GCE as working electrode showed a linear current response to the target QCA concentration in the wide range from 2.0×10(-6) to 1.0×10(-3)molL(-1) with a low detection limit of 4.4×10(-7)molL(-1) (S/N=3). The established sensor with excellent reproductivity and stability was applied to evaluate commercial pork products. At five concentration levels, the recoveries and standard deviations were calculated as 93.5-98.6% and 1.7-3.3%, respectively, suggesting the proposed sensor is promising for the accurate quantification of QCA at trace levels in meat samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Studies on radiation stability of polymers

International Nuclear Information System (INIS)

Jiazhen Sun; Xiaoguang Zhong

1999-01-01

Fluoropolyimide (FPI) is crosslinked by gamma-irradiation at high temperature. After crosslinking, the glass transition temperature is increased with increasing dose. High temperature tensile strength is also increased with increasing dose. The high temperature water resistance property is improved markedly. XPS results show that the fluoro-atom in the CF 3 group is decreased during radiation crosslinking of PFI, so the crosslinking reaction of PFI is thought to proceed through defluorination. Likewise, certain common polyolefins, such as polytetrafluoroethylene, which undergo primarily chain scission when irradiated at room temperature, can be crosslinked by irradiation at high temperature. This dramatically improves their subsequent radiation resistance. We have also been able to achieve improved radiation resistance by irradiation of certain blends of a predominantly scissioning polymer with a predominantly crosslinking polymer. (author)

Fourier transform Raman spectroscopy of polyacrylamide gels for radiation dosimetry

International Nuclear Information System (INIS)

Baldock, C.; Murry, P.; Pope, J.; Rintoul, L.; George, G.

1998-01-01

Polyacrylamide (PAG) gels are used in magnetic resonance imaging radiation dosimetry. The PAG dosimeter is based on the radiation-induced co-polymerisation and cross-linking of acrylic monomers infused in a gel matrix. PAG was manufactured with a composition of 5% gelatine, 3% acrylamide and 3% N,N'methylene-bis-acrylamide by mass, with distilled water as the remaining constituent [Baldock, 1998]. FT-Raman spectroscopy studies were undertaken to investigate cross-linking changes during the co-polymerisation of PAG in the spectral range of 200 - 3500 cm -1 . Vibrational bands of 1285 cm -1 and 1256 cm -1 were assigned to the acrylamide and bis-acrylamide single CH 2 δ CH2 binding modes. These bands were found to decrease in amplitude with increasing absorbed radiation dose, as a result of co-polymerisation. Principal Component Regression was performed on FT-Raman spectra of PAG samples irradiated to 50 Gy and two components were found to be sufficient to account for 98.7% of variance in the data. Cross validation was used to establish the absorbed radiation dose of an unknown PAG sample from the FT-Raman spectra. The calculated correlation coefficient between measured and predictive samples was 0.997 with a standard error of estimate of 0.976 and a standard error of prediction of 1.140. These results demonstrate the potential of FT-Raman spectroscopy for ionising radiation dosimetry using polyacrylamide gels

Radiation synthesis and modification of polymers for biomedical applications. Final results of a co-ordinated research project. 1996-2000

Energy Technology Data Exchange (ETDEWEB)

NONE

2002-12-01

Radiation techniques are being used for synthesis of hydrogels, functional polymers, interpenetrating systems, chemical modification of surfaces, immobilization of bioactive materials, synthesis of functional micro- and nanospheres and processing of naturally derived biomaterials. Potential medical applications of these biomaterials include implants, topical dressings, treatment devices and drug delivery systems. Biotechnological applications include diagnostic assays, separation and purification systems, immobilized enzyme and cell bioprocesses and cell culture surfaces. The main objective of the CRP on The use of Radiation Processing to Prepare Biomaterials for Application in Medicine was to co-ordinate the research carried out in the participating countries, to ensure that different research programmes complement each other and the information exchange is available to all. Furthermore, the objective was to expand the use of ionizing radiation in two major areas: synthesis of polymers and gels for medical and biotechnological applications, and modification of surfaces to achieve a specific functionality and/or to immobilize bioactive materials. This publication contains 10 reports of participants; each of the reports has been indexed separately.

Radiation synthesis and modification of polymers for biomedical applications. Final results of a co-ordinated research project. 1996-2000

International Nuclear Information System (INIS)

2002-12-01

Radiation techniques are being used for synthesis of hydrogels, functional polymers, interpenetrating systems, chemical modification of surfaces, immobilization of bioactive materials, synthesis of functional micro- and nanospheres and processing of naturally derived biomaterials. Potential medical applications of these biomaterials include implants, topical dressings, treatment devices and drug delivery systems. Biotechnological applications include diagnostic assays, separation and purification systems, immobilized enzyme and cell bioprocesses and cell culture surfaces. The main objective of the CRP on The use of Radiation Processing to Prepare Biomaterials for Application in Medicine was to co-ordinate the research carried out in the participating countries, to ensure that different research programmes complement each other and the information exchange is available to all. Furthermore, the objective was to expand the use of ionizing radiation in two major areas: synthesis of polymers and gels for medical and biotechnological applications, and modification of surfaces to achieve a specific functionality and/or to immobilize bioactive materials. This publication contains 10 reports of participants; each of the reports has been indexed separately

Gel nano-particulates against radioactivity; Des nanoparticules en gel contre la radioactivite

Energy Technology Data Exchange (ETDEWEB)

Deroin, Ph

2004-11-01

The Argonne research center (USA) has developed a 'super-gel' compound, a polymer close to those used in baby's diapers, which can reach a 90% efficiency in the radioactive decontamination of porous materials, like bricks or concrete. The contaminated materials are sprayed with a mixture of polymer gel and wetting agent with nano-particulates in suspension. Under the action of the wetting agent, radioactivity migrates from the pores to the gel and is trapped by the nano-particulates. The drying and recycling of the gel allows to reduce the volume of radioactive wastes. Short paper. (J.S.)

Radiation processed polychloroprene-co-ethylene-propene diene terpolymer blends: Effect of radiation vulcanization on solvent transport kinetics

Energy Technology Data Exchange (ETDEWEB)

Dubey, K.A. [Radiation Technology Development Section, Bhabha Atomic Research Centre, Room No. S-1, HIRUP Building, Trombay, Mumbai 400 085 (India); Bhardwaj, Y.K. [Radiation Technology Development Section, Bhabha Atomic Research Centre, Room No. S-1, HIRUP Building, Trombay, Mumbai 400 085 (India)], E-mail: ykbhard@barc.gov.in; Chaudhari, C.V.; Kumar, Virendra; Goel, N.K.; Sabharwal, S. [Radiation Technology Development Section, Bhabha Atomic Research Centre, Room No. S-1, HIRUP Building, Trombay, Mumbai 400 085 (India)

2009-03-15

Blends of polychloroprene rubber (PCR) and ethylene propylene diene terpolymer rubber (EPDM) of different compositions were made and exposed to different gamma radiation doses. The radiation sensitivity and radiation vulcanization efficiency of blends was estimated by gel-content analysis, Charlesby-Pinner parameter determination and crosslinking density measurements. Gamma radiation induced crosslinking was most efficient for EPDM (p{sub 0}/q{sub 0} {approx} 0.08), whereas it was the lowest for blends containing 40% PCR (p{sub 0}/q{sub 0} {approx} 0.34). The vulcanized blends were characterized for solvent diffusion characteristics by following the swelling dynamics. Blends with higher PCR content showed anomalous swelling. The sorption and permeability of the solvent were not strictly in accordance with each other and the extent of variation in two parameters was found to be a function of blend composition. The {delta}G values for solvent diffusion were in the range -2.97 to -9.58 kJ/mol and indicated thermodynamically favorable sorption for all blends. These results were corroborated by dynamic swelling, experimental as well as simulated profiles and have been explained on the basis of correlation between crosslinking density, diffusion kinetics, thermodynamic parameters and polymer-polymer interaction parameter.

Synthesis of Silica Nanoparticles by Sol-Gel: Size-Dependent Properties, Surface Modification, and Applications in Silica-Polymer Nano composites-A Review

International Nuclear Information System (INIS)

Ismail, A.R.; Vejayakumaran, P.

2012-01-01

Application of silica nanoparticles as fillers in the preparation of nano composite of polymers has drawn much attention, due to the increased demand for new materials with improved thermal, mechanical, physical, and chemical properties. Recent developments in the synthesis of monodispersed, narrow-size distribution of nanoparticles by sol-gel method provide significant boost to development of silica-polymer nano composites. This paper is written by emphasizing on the synthesis of silica nanoparticles, characterization on size-dependent properties, and surface modification for the preparation of homogeneous nano composites, generally by sol-gel technique. The effect of nano silica on the properties of various types of silica-polymer composites is also summarized.

Fabrication and Optimization of a PAGATA Gel Dosimeter: Increasing the Melting Point of the PAGAT Gel Dosimeter with Agarose Additive

Directory of Open Access Journals (Sweden)

Bakhtiar Azadbakht

2010-12-01

Full Text Available Introduction: The PAGAT polymer gel dosimeter melts at 30 ˚C and even at room temperature during the summer, so it needs to be kept in a cool place such as a refrigerator. To increase the stability of the PAGAT gel, different amounts of agarose were added to the PAGAT gel composition and the PAGATA gel was manufactured. Material and Methods: The PAGATA gel vials were irradiated using a Co-60 machine. Then, the samples were evaluated using a 1.5 T Siemens MRI scanner. The ingredients of the PAGATA normoxic gel dosimeter were 4.5% N-N' methylen-bis-acrylamide, 4.5% acrylamide, 4.5% gelatine, 5 mM tetrakis (THPC, 0.01 mM hydroquinone (HQ, 0.5% agarose and 86% de-ionized water (HPLC. Results: Melting point and sensitivity of the PAGAT gel dosimeter with addition of 0.0, 0.3, 0.5, 1.0, 1.5 and 2.0% of agarose were measured, in which the melting points were increased to 30, 82, 86, 88, 89 and 90°C and their sensitivities found to be 0.113, 0.1059, 0.125, 0.122, 0.115 and 0.2  respectively. Discussion and Conclusions: Adding agarose increased the sensitivity and background R2 of the evaluated samples. The optimum amount of agarose was found to be 0.5% regarding these parameters and also the melting point of the gel dosimeter. A value of 0.5% agarose was found to be an optimum value considering the increase of sensitivity to 0.125 and melting point to 86°C but at the expense of increasing the background R2 to 4.530.

Introduction of a deformable x-ray CT polymer gel dosimetry system

Science.gov (United States)

Maynard, E.; Heath, E.; Hilts, M.; Jirasek, A.

2018-04-01

This study introduces the first 3D deformable dosimetry system based on x-ray computed tomography (CT) polymer gel dosimetry and establishes the setup reproducibility, deformation characteristics and dose response of the system. A N-isopropylacrylamide (NIPAM)-based gel formulation optimized for x-ray CT gel dosimetry was used, with a latex balloon serving as the deformable container and low-density polyethylene and polyvinyl alcohol providing additional oxygen barrier. Deformable gels were irradiated with a 6 MV calibration pattern to determine dosimetric response and a dosimetrically uniform plan to determine the spatial uniformity of the response. Wax beads were added to each gel as fiducial markers to track the deformation and setup of the gel dosimeters. From positions of the beads on CT images the setup reproducibility and the limits and reproducibility of gel deformation were determined. Comparison of gel measurements with Monte Carlo dose calculations found excellent dosimetric accuracy, comparable to that of an established non-deformable dosimetry system, with a mean dose discrepancy of 1.5% in the low-dose gradient region and a gamma pass rate of 97.9% using a 3%/3 mm criterion. The deformable dosimeter also showed good overall spatial dose uniformity throughout the dosimeter with some discrepancies within 20 mm of the edge of the container. Tracking of the beads within the dosimeter found that sub-millimetre setup accuracy is achievable with this system. The dosimeter was able to deform and relax when externally compressed by up to 30 mm without sustaining any permanent damage. Internal deformations in 3D produced average marker movements of up to 12 mm along the direction of compression. These deformations were also shown to be reproducible over 100 consecutive deformations. This work has established several important characteristics of a new deformable dosimetry system which shows promise for future clinical applications, including the

Trend and future of radiation processing of polymers

International Nuclear Information System (INIS)

Makuuchi, Keizo

2000-01-01

Five Asian countries have been cooperating with Takasaki Radiation Chemistry Research Establishment (TRCRE), Japan, in the field of radiation processing of polymers. The experience of cooperation is summarized. Main processes are polymerization of monomers, cross-linking and degradation of polymers, graft polymerization and curing. The industrial state-of-art of radiation processing in Japan is described. The characteristics of radiation processes are compared with other processes. The future prospect of processing is also described. The growth in cross-linking and degradation are anticipated, whereas graft polymerization and curing are to confront to severe competition with other methods. The possibility of developing new area of radiation processing in Asian counties is pointed out. (A. Yamamoto)

Investigation of P(VDF-TrFE)/ZrO{sub 2}-MMA polymer composites applied to radiation shielding

Energy Technology Data Exchange (ETDEWEB)

Fontainha, C.C.P. [Depto. de Engenharia Nuclear - UFMG, Av. Antonio Carlos 6627, 31270-970 Belo Horizonte, MG (Brazil); Baptista Neto, A.T.; Santos, A.P.; Faria, L.O. [Centro de Desenvolvimento da Tecnologia Nuclear, Av. Antonio Carlos 6627, C.P. 941, 30270-901, Belo Horizonte, MG (Brazil)

2015-07-01

Exposure to high radiation dose in medical diagnostic imaging procedures can lead patients to suffer tissue damaging. However, there are several studies that identify significant dose reduction with the use of radiation protective attenuators, minimizing the delivered dose in the region that covers the main beam, while preserving the diagnostic quality of the generated image. Most radiation attenuator materials are produced from shielding metal containing composites, whose efficiency is the goal of investigations around the world. In this context, polymeric materials were chosen for this investigation in order to provide light-weighted and flexible protective composites, a must in personal protective shielding. Therefore, this work is concerned to the investigation of poly(vinylidene fluoride - try-fluor-ethylene) [P(VDF-TrFE)] copolymers mixed with zirconia nanoparticles. The resulting polymer composites, prepared with 1, 2, 3, 5 and 10 at.% of ZrO{sub 2} nanoparticles, were investigated for application as protective shielding in some interventional radiology procedures. Two variety of composites were produced, one using pure ZrO{sub 2} nanoparticles and the other using sol-gel route with zirconium butoxide as the precursor for zirconium oxide nano-clusters. The P(VDFTrFE)/ ZrO2-MMA polymer composites produced by sol-gel route have provided a much better dispersion of the pure ZrO{sub 2} material into the P(VDF-TrFE) host matrix. UV-Vis and FTIR spectrometry and differential scanning calorimetry (DSC) were used to characterize the composite samples. FTIR data reveal a possible link between the MMA monomers with the P(VDF-TrFE) chain through shared C=O bonds. The radiation shielding characterization was conducted by using a 70 kV x-rays beam which is applicable, for instances, in catheter angiography. The results demonstrate that composites with 10% of ZrO{sub 2}, and only 1.0 mm thick, can attenuate 60% of the x-rays beam. The composite density was evaluated to be

Controlled Sol-Gel Transitions of a Thermoresponsive Polymer in a Photoswitchable Azobenzene Ionic Liquid as a Molecular Trigger.

Science.gov (United States)

Wang, Caihong; Hashimoto, Kei; Tamate, Ryota; Kokubo, Hisashi; Watanabe, Masayoshi

2018-01-02

Producing ionic liquids (ILs) that function as molecular trigger for macroscopic change is a challenging issue. Photoisomerization of an azobenzene IL at the molecular level evokes a macroscopic response (light-controlled mechanical sol-gel transitions) for ABA triblock copolymer solutions. The A endblocks, poly(2-phenylethyl methacrylate), show a lower critical solution temperature in the IL mixture containing azobenzene, while the B midblock, poly(methyl methacrylate), is compatible with the mixture. In a concentrated polymer solution, different gelation temperatures were observed in it under dark and UV conditions. Light-controlled sol-gel transitions were achieved by a photoresponsive solubility change of the A endblocks upon photoisomerization of the azobenzene IL. Therefore, an azobenzene IL as a molecular switch can tune the self-assembly of a thermoresponsive polymer, leading to macroscopic light-controlled sol-gel transitions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A preliminary assessment of the effects of radiation on polymer properties

International Nuclear Information System (INIS)

Dickson, L.W.

1988-01-01

The literature on the effects of radiation on the properties of various polymers and composites has been briefly reviewed for the purpose of identifying polymeric materials that could be irradiated to improve their performance. Radiation treatment of polymers may lead to cross-linking or chain scission reactions, depending on the chemical nature of the polymer. Cross-linking generally leads to an improvement in the mechanical properties of the polymer. Chain scission leads to deterioration in mechanical properties. The properties of irradiated polymers also depend on the degree of polymer crystallinity and the irradiation conditions, including dose rate and the presence of oxygen, cross-linking agents and other additives. A 30% increase in the tensile strength of many polymers may be obtained by radiation cross-linking under appropriate conditions. 40 refs

Study on the kinetics of gel formation in the radiation crosslinking reaction

International Nuclear Information System (INIS)

Wang Mingjun; Liu Yuming

1988-01-01

From the kinetic equation of gel formation obtained by the authors, the mechanism of gel formation may be interpreted clearly as follows: (1) When the degree of crosslinking q g , the system is sol and the crosslinking reaction is only carried out between the sol molecules. (q g is the gel point). (2) When q=q g , there exists a beginning point where the gel is coexisted with the sol, and the system is still sol, and the crosslinking reaction is still carried out between the sol molecules. (3) When q>q g , the crosslinking reaction exceeds the gel point and the gel is coexisted with the sol. The kinetic equation shows clearly that the transformation from sol into gel is caused by crosslinking reaction of the uncrosslinked chain units between the sol and gel molecules. As a result the sol molecules are transformed into the gel molecules gradually, and the sol fraction is reduced. When the chain units P-barw(s)S(1-s)dq in sol are crosslinked with gel, the sol fraction in the system is reduced ds (where P-barw(s) is a function of the radiation dose and s is sol frection). The degree of crosslinking per unit dose (q 0 ) is a reduced function of dose (R). The equation for calculating its value for every irradiation dose is obtained. After knowing the correlation between P-bar W(s) vs R and q 0 vs R, the distribution of gel and sol in the process of radiation crosslinking can be discussed as well

based gel polymer electrolytes

Indian Academy of Sciences (India)

(PVdF) as a host polymer, lithium perchlorate (LiClO4), lithium triflate ... TG/DTA studies showed the thermal stability of the polymer electrolytes. .... are observed while comparing pure XRD spectra with .... batteries as its operating temperature is normally in the .... chain ion movements and the conductivity of the polymer.

The effect of chain flexibility and chain mobility on radiation crosslinking reactions of polymers

International Nuclear Information System (INIS)

Sun Jiazhen

2003-01-01

Flexibility of polymer chains is an important factor to effects of radiation crosslinking of the polymer. Polymers with flexible chains are easier to be crosslinked, with lower dose of gelation, than polymers with more rigid chains. And it is known that most polymers with abnormal rigidity can be radiation-crosslinked only at high temperatures when the molecular chains get enough mobility. The flexibility of polymer chains also influences the relationship between degree of degradation and radiation dose. A chain flexibility factor β has been introduced to modify the Charlesby-Pinner equation of sol-fraction and radiation dose. The new relationship equation applies to a wider range of polymers in radiation crosslinking. Studies also show that for flexible polymers with lower T g and molecular internal rotating factor, mechanism of radiation crosslinking is mainly in H type, whereas for rigid polymers with higher T g and molecular internal rotating factor, mechanism of radiation crosslinking is mainly in T type

Stimuli responsive ion gels based on polysaccharides and other polymers prepared using ionic liquids and deep eutectic solvents.

Science.gov (United States)

Prasad, Kamalesh; Mondal, Dibyendu; Sharma, Mukesh; Freire, Mara G; Mukesh, Chandrakant; Bhatt, Jitkumar

2018-01-15

Ion gels and self-healing gels prepared using ionic liquids (ILs) and deep eutectic solvents (DESs) have been largely investigated in the past years due to their remarkable applications in different research areas. Herewith we provide an overview on the ILs and DESs used for the preparation of ion gels, highlight the preparation and physicochemical characteristics of stimuli responsive gel materials based on co-polymers and biopolymers, with special emphasis on polysaccharides and discuss their applications. Overall, this review summarizes the fundamentals and advances in ion gels with switchable properties prepared using ILs or DESs, as well as their potential applications in electrochemistry, in sensing devices and as drug delivery vehicles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Formation of physical-gel redox electrolytes through self-assembly of discotic liquid crystals: Applications in dye sensitized solar cells

International Nuclear Information System (INIS)

Khan, Ammar A.; Kamarudin, Muhammad A.; Qasim, Malik M.; Wilkinson, Timothy D.

2017-01-01

The self-assembly of small molecules into ordered structures is of significant interest in electronic applications due to simpler device fabrication and better performance. Here we present work on the development of self-assembled fibrous networks of thermotropic triphenylene discotic liquid crystals, where 2,3,6,7,10,11-Hexakishexyloxytriphenylene (HAT6) is studied. The formation of interconnected molecular fibres in acetonitrile-based solvents facilitates thermally-reversible physical-gel (non-covalent) preparation, with the HAT6 network providing mechanical support and containment of the solvent. Furthermore, gel formation is also achieved using an acetonitrile-based iodide/tri-iodide redox liquid electrolyte, and the resulting gel mixture is utilised as an electrolyte in dye-sensitized solar cells (DSSCs). Our results show that it is indeed possible to achieve in situ gel formation in DSSCs, allowing for easy cell fabrication and electrolyte filling. In addition, the gel phase is found to increase device lifetime by limiting solvent evaporation. Differential scanning calorimetry (DSC) and polarising optical microscopy (POM) are used to study gel formation, and it is identified that the thermally reversible gels are stable up to working temperatures of 40 °C. It is found that DSSCs filled with gel electrolyte exhibit longer electron lifetime in the TiO 2 photo-anode (≈8.4 ms in the liquid electrolyte to ≈11.4 ms in the gel electrolytes), most likely due to electron screening from the electrolyte by HAT6. Current-Voltage (I–V) and electrochemical impedance spectroscopy (EIS) are used to study the effect of gel formation on conductivity and electrochemical properties, and it is found that confinement of the liquid electrolyte into a gel phase does not significantly reduce ionic conductivity, a problem common with solid-state polymer electrolytes. A 3.8 mM HAT6 gel electrolyte DSSC exhibited a PCE of 6.19% vs. a 5.86% liquid electrolyte reference. Extended

Radiation hardening of sol gel-derived silica fiber preforms through fictive temperature reduction.

Science.gov (United States)

Hari Babu, B; Lancry, Matthieu; Ollier, Nadege; El Hamzaoui, Hicham; Bouazaoui, Mohamed; Poumellec, Bertrand

2016-09-20

The impact of fictive temperature (Tf) on the evolution of point defects and optical attenuation in non-doped and Er3+-doped sol-gel silica glasses was studied and compared to Suprasil F300 and Infrasil 301 glasses before and after γ-irradiation. To this aim, sol-gel optical fiber preforms have been fabricated by the densification of erbium salt-soaked nanoporous silica xerogels through the polymeric sol-gel technique. These γ-irradiated fiber preforms have been characterized by FTIR, UV-vis-NIR absorption spectroscopy, electron paramagnetic resonance, and photoluminescence measurements. We showed that a decrease in the glass fictive temperature leads to a decrease in the glass disorder and strained bonds. This mainly results in a lower defect generation rate and thus less radiation-induced attenuation in the UV-vis range. Furthermore, it was found that γ-radiation "hardness" is higher in Er3+-doped sol-gel silica compared to un-doped sol-gel silica and standard synthetic silica glasses. The present work demonstrates an effective strategy to improve the radiation resistance of optical fiber preforms and glasses through glass fictive temperature reduction.

Synthesis and Exciton Dynamics of Triplet Sensitized Conjugated Polymers

KAUST Repository

Andernach, Rolf

2015-07-22

We report the synthesis of a novel polythiophene-based host-guest copolymer incorporating a Pt-porphyrin complex (TTP-Pt) into the backbone for efficient singlet to triplet polymer exciton sensitization. We elucidated the exciton dynamics in thin films of the material by means of Transient Absorption Spectrosopcy (TAS) on multiple timescales and investigated the mechanism of triplet exciton formation. During sensitization, single exciton diffusion is followed by exciton transfer from the polymer backbone to the complex where it undergoes intersystem crossing to the triplet state of the complex. We directly monitored the triplet exciton back transfer from the Pt-porphyrin to the polymer and find that 60% of the complex triplet excitons are transferred with a time constant of 1087 ps. We propose an equilibrium between polymer and porphyrin triplet states as a result of the low triplet diffusion length in the polymer backbone and hence an increased local triplet population resulting in increased triplet-triplet annihilation. This novel system has significant implications for the design of novel materials for triplet sensitized solar cells and up-conversion layers.

Polymerization of unsaturated monomers with radiation in the presence of salts

International Nuclear Information System (INIS)

Phalangas, C.J.; Restaino, A.J.; Yun, H.B.

1977-01-01

Improved process is claimed for the preparation of water-soluble, substantially linear, high molecular weight polymers, comprising irradiating an aqueous solution of an ethylenically unsaturated monomer and a water-soluble salt under controlled conditions of concentration, radiation intensity, conversion, and total radiation dose. The polymers may be obtained in aqueous gel form or recovered in the form of powder. The polymers are useful as flocculating, thickening, and mobility control agents

Polymer-Particle Pressure-Sensitive Paint with High Photostability

Directory of Open Access Journals (Sweden)

Yu Matsuda

2016-04-01

Full Text Available We propose a novel fast-responding and paintable pressure-sensitive paint (PSP based on polymer particles, i.e. polymer-particle (pp-PSP. As a fast-responding PSP, polymer-ceramic (PC-PSP is widely studied. Since PC-PSP generally consists of titanium (IV oxide (TiO2 particles, a large reduction in the luminescent intensity will occur due to the photocatalytic action of TiO2. We propose the usage of polymer particles instead of TiO2 particles to prevent the reduction in the luminescent intensity. Here, we fabricate pp-PSP based on the polystyrene particle with a diameter of 1 μm, and investigate the pressure- and temperature-sensitives, the response time, and the photostability. The performances of pp-PSP are compared with those of PC-PSP, indicating the high photostability with the other characteristics comparable to PC-PSP.

Cleaning and Restoration of an Oil Painting with a Polymer Gel in Iran

Directory of Open Access Journals (Sweden)

Siyamak Alizadeh

2018-03-01

Full Text Available One of the major stages in the conservation and restoration of a painting is to clean its colored surface of unwanted stains, and old and darkened varnishes. Various solvents have been used to date for this purpose; however, new cleaning materials have also come onto the market in the past decade that are still unknown and may never have been employed in Iran. The present study aims to introduce a polymer gel and use an in vitro sample of the substance for cleaning and to then present the results of the tests carried out. Applying a polymer gel in the cleaning of paintings yielded better results and greater advantages over the solvents previously used to clean artworks. The advantages include, performing on the surface without penetrating the lower layers, the absence of residues after application, flexibility, solubility and the gentle removal of old stains and varnishes, maintaining clarity and cleaning the surface by simple removal of the thin dried layer, which requires no mechanical pressure. Microscopic examinations and pH testing showed that this new alternative technique can be of use in cleaning the color layers of oil paintings.

Preliminary investigation of the NMR, optical and x-ray CT dose-response of polymer gel dosimeters with cosolvents and increased crosslinker levels

International Nuclear Information System (INIS)

Koeva, V I; McAuley, K B; Jirasek, A; Schreiner, L J

2009-01-01

Three co-solvents (glycerol, N-propanol and isopropanol) have been investigated for increasing the solubility of N,N'-methylene-bisacrylamide (Bis) crosslinker in polymer gel dosimeter recipes. Using isopropanol, the crosslinker solubility increased from approximately from 3 to 10% by weight, enabling the manufacture of polymer gel dosimeters with higher levels of crosslinking than was previously possible. The new dosimeter recipes can be imaged effectively using Nuclear Magnetic Resonance (NMR), optical and x-ray Computed Tomography (CT) techniques.

Preliminary investigation of the NMR, optical and x-ray CT dose-response of polymer gel dosimeters with cosolvents and increased crosslinker levels

Energy Technology Data Exchange (ETDEWEB)

Koeva, V I; McAuley, K B [Chemical Engineering Department, Queen' s University, Kingston, K7L 3N6 (Canada); Jirasek, A [Department of Physics and Astronomy, University of Victoria, Victoria, V8W 6V5 (Canada); Schreiner, L J [Cancer Centre of Southeastern Ontario, Kingston, K7L 5P9 (Canada)], E-mail: Kim.McAuley@chee.queensu.ca

2009-05-01

Three co-solvents (glycerol, N-propanol and isopropanol) have been investigated for increasing the solubility of N,N'-methylene-bisacrylamide (Bis) crosslinker in polymer gel dosimeter recipes. Using isopropanol, the crosslinker solubility increased from approximately from 3 to 10% by weight, enabling the manufacture of polymer gel dosimeters with higher levels of crosslinking than was previously possible. The new dosimeter recipes can be imaged effectively using Nuclear Magnetic Resonance (NMR), optical and x-ray Computed Tomography (CT) techniques.

Radiation deterioration of several aromatic polymers under oxidative conditions

International Nuclear Information System (INIS)

Sasuga, Tsuneo; Hagiwara, Miyuki

1987-01-01

Radiation-induced oxidative irradiation effects (with γ-rays under oxygen pressure) or poly(aryl sulphones) (U-PS and PES), poly(aryl ester) (U-Polymer), poly(aryl amide) (A-Film) and poly(aryl ether ether ketone) (PEEK) have been studied based on changes in tensile properties. The deterioration dose estimated from the decrease in the elongation at break was as low as one-fifth to one-tenth of that in high-dose-rate electron-beam irradiation, but the order of radiation resistance of the polymers did not differ from that in electron-beam irradiation, i.e. PEEK > A-Film > U-Polymer > U-PS > PES. The radiation stability of aromatic units under oxidative conditions was estimated from a comparison of the radiation resistance of the polymers themselves and their chemical structures. The following order was obtained: diphenyl ether, diphenyl ketone > aromatic amide>> bisphenol A > diphenyl sulphone. The deterioration mechanism of PEEK under oxidative irradiation was studied by measuring dynamic viscoelastic properties. It was concluded that deterioration in mechanical properties under oxidative irradiation was brought about by chain scission only. (author)

Cellulose gels produced in room temperature ionic liquids by ionizing radiation

International Nuclear Information System (INIS)

Kimura, Atsushi; Nagasawa, Naotsugu; Taguchi, Mitsumasa

2014-01-01

Cellulose-based gels were produced in room temperature ionic liquids (RTILs) by ionizing radiation. Cellulose was dissolved at the initial concentration of 20 wt% in 1-ethyl-3-methylimidazolium (EMI)-acetate or N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium (DEMA)-formate with a water content of 18 wt%, and irradiated with γ-rays under aerated condition to produce new cellulose gels. The gel fractions of the cellulose gels obtained in EMI-acetate and DEMA-formate at a dose of 10 kGy were 13% and 19%, respectively. The formation of gel fractions was found to depend on the initial concentration of cellulose, water content, and irradiation temperature. The obtained gel readily absorbed water, methanol, ethanol, dichloromethane, N,N-dimethylacetamide, and RTILs. - Highlights: • Cellulose gels were produced in room temperature ionic liquids (RTILs). • Water plays a crucial role in the cross-linking reaction. • Cellulose gels swollen with RTILs show good electronic conductivity (3.0 mS cm −1 )

Enhancing the performance of dye-sensitized solar cells by incorporating nanomica in gel electrolytes☆

KAUST Repository

Lai, Yi-Hsuan; Lin, Chia-Yu; Chen, Jian-Ging; Wang, Chun-Chieh; Huang, Kuan-Chieh; Liu, Ken-Yen; Lin, King-Fu; Lin, Jiang-Jen; Ho, Kuo-Chuan

2010-01-01

Gel-type dye-sensitized solar cells (DSSCs) were fabricated with 5.0 wt% polyvinyidene fluoride-co-hexafluoro propylene (PVDF-HFP) in methoxy propionitrile (MPN) as gel polymer electrolyte (GPE), 1-butyl-3-methylimidazolium iodide (BMII)/iodine (I2) as redox couple, 4-tertiary butyl pyridine (TBP) and guanidine thiocyanate as additives. The incorporation of alkyl-modified nanomica (AMNM) in the PVDF-HFP gel electrolytes caused the reduction of crystallization of PVDF-HFP, which was confirmed by X-ray diffraction (XRD) analysis. The short-circuit current density (JSC) of the cell increased due to the decrease of diffusion resistance, as judged by the electrochemical impedance spectra (EIS) analysis, while the open-circuit voltage (VOC) remained almost the same. As the loading of AMNM in the PVDF-HFP gel electrolyte was increased to 3.0 wt%, the JSC and power conversion efficiency (η) of the cells increased from 8.3 to 13.6 mA/cm2 and 3.5% to 5.7%, respectively. However, the JSC decreased as the loading of AMNM exceeded 3.0 wt%. At higher AMNM loadings, nanomica acted as a barrier interface between the electrolyte and the dye molecules to hinder electron transfer, and thus reducing the cell's photocurrent density. Furthermore, the DSSCs fabricated by dispersing polymethyl methacrylate (PMMA) microspheres in the TiO2 electrode with the GPE containing 3.0 wt% AMNM improved the η to 6.70%. The TiO2 films would exhibit larger porosity by blending with PMMA, leading the penetration of GPEs into the porous TiO2 easier, thus improving the contact between the dye-adsorbed TiO2 surfaces and the GPEs, as characterized by EIS. Moreover, the η of gel-type DSSCs with a 25 μm thickness of surlyn reached 7.96% as compared with 6.70% for the DSSCs with a 60 μm surlyn. © 2009 Elsevier B.V. All rights reserved.

Enhancing the performance of dye-sensitized solar cells by incorporating nanomica in gel electrolytes☆

KAUST Repository

Lai, Yi-Hsuan

2010-04-01

Gel-type dye-sensitized solar cells (DSSCs) were fabricated with 5.0 wt% polyvinyidene fluoride-co-hexafluoro propylene (PVDF-HFP) in methoxy propionitrile (MPN) as gel polymer electrolyte (GPE), 1-butyl-3-methylimidazolium iodide (BMII)/iodine (I2) as redox couple, 4-tertiary butyl pyridine (TBP) and guanidine thiocyanate as additives. The incorporation of alkyl-modified nanomica (AMNM) in the PVDF-HFP gel electrolytes caused the reduction of crystallization of PVDF-HFP, which was confirmed by X-ray diffraction (XRD) analysis. The short-circuit current density (JSC) of the cell increased due to the decrease of diffusion resistance, as judged by the electrochemical impedance spectra (EIS) analysis, while the open-circuit voltage (VOC) remained almost the same. As the loading of AMNM in the PVDF-HFP gel electrolyte was increased to 3.0 wt%, the JSC and power conversion efficiency (η) of the cells increased from 8.3 to 13.6 mA/cm2 and 3.5% to 5.7%, respectively. However, the JSC decreased as the loading of AMNM exceeded 3.0 wt%. At higher AMNM loadings, nanomica acted as a barrier interface between the electrolyte and the dye molecules to hinder electron transfer, and thus reducing the cell\\'s photocurrent density. Furthermore, the DSSCs fabricated by dispersing polymethyl methacrylate (PMMA) microspheres in the TiO2 electrode with the GPE containing 3.0 wt% AMNM improved the η to 6.70%. The TiO2 films would exhibit larger porosity by blending with PMMA, leading the penetration of GPEs into the porous TiO2 easier, thus improving the contact between the dye-adsorbed TiO2 surfaces and the GPEs, as characterized by EIS. Moreover, the η of gel-type DSSCs with a 25 μm thickness of surlyn reached 7.96% as compared with 6.70% for the DSSCs with a 60 μm surlyn. © 2009 Elsevier B.V. All rights reserved.

Mechanism of radiation destruction of dyes in polymers

International Nuclear Information System (INIS)

Belichenko, A.S.; Dyumaev, K.M.; Maslyukov, A.P.; Matyushin, G.A.; Nechitailo, V.S.

1991-01-01

Considering the experimental results, it might be expected that the mechanism of radiation destruction of dyed polymers by UV-and γ-irradiation should also be associated with a chemical reaction between dye molecules and oxyradicals which appear either on destruction of polymer macromolecules or on oxidation of macroradicals by the oxygen dissolved in the matrix. Thus, the radiation stability of dyes should depend on the rate of formation of primary radicals in the polymer under the action of UV- and γ-irradiation. As has been demostrated, this rate can be influenced by 'resonant' low-molecular additives which perform oscillative cross-relaxation. (author) 8 refs.; 2 figs

Role of polymer matrix on photo-sensitivity of CdSe polymer nanocomposites

Science.gov (United States)

Kaur, Ramneek; Tripathi, S. K.

2018-04-01

This paper reports the effect of three different polymer matrices (PVP, PMMA and PVK) and Ag doping on the photo-sensitivity of CdSe polymer nanocomposites. The results reveal that the photoconductivity is high for linear chain polymer nanocomposites as compared to aromatic ones with decreasing trend as: CdSe-PMMA > CdSe-PVP > CdSe-PVK. The large substituents or branches along the polymer backbone hinder the stacking sequences in CdSe-PVK nanocomposites resulting in lowest photoconductivity. On contrary, CdSe-PVK nanocomposite exhibit highest photosensitivity. The reason behind it is the low value of dark conductivity in CdSe-PVK nanocomposite and photoconductive PVK matrix. With Ag doping, no considerable effect on the value of photosensitivity has been observed. The obtained results indicate that the photo-conducting properties of these polymer nanocomposites can be tuned by using different polymer matrices.

New Microporous Polymer Electrolyte Based on Polysiloxane Grafted with Imidazolium Iodide Moieties for DSSC

Directory of Open Access Journals (Sweden)

Yan Yang

2011-01-01

Full Text Available Two types of polysiloxane grafted with different ratio of imidazolium iodide moieties (IL-SiO2 have been synthesized to develop a micro-porous polymer electrolyte for quasi-solid-state dye-sensitized solar cells. The samples were characterized by 1HNMR, FT-IR spectrum, XRD, TEM and SEM, respectively. Moreover, the ionic conductivity of the electrolytes was measured by electrochemical workstation. Nanostructured polysiloxane containing imidazolium iodide showed excellent compatibility with organic solvent and polymer matrix for its ionic liquid characteristics. Increasing the proportion of imidazolium iodide moieties in polysiloxane improved the electrochemical behavior of the gel polymer electrolyte. A dye-sensitized solar cell with gel polymer electrolyte yielded an open-circuit voltage of 0.70 V, short-circuit current of 11.19 mA cm−2, and the conversion efficiency of 3.61% at 1 sun illumination.

Thermal Degradation and Identification of Heat-Sensitive Polymers

Science.gov (United States)

Clough, Stuart C.; Goldman, Emma W.

2005-01-01

A study demonstrates the thermal degradation of two heat-sensitive polymers, namely, polystyrene and poly (methyl methacrylate). The experiment described in the study introduces undergraduate students to polymer structure as well as the application of spectroscopic techniques to the solution of structural problems.

Electrochemical Impedance Spectroscopy Studies of Magnesium-Based Polymethylmethacrylate Gel Polymer Electroytes

International Nuclear Information System (INIS)

Osman, Z.; Zainol, N.H.; Samin, S.M.; Chong, W.G.; Md Isa, K.B.; Othman, L.; Supa’at, I.; Sonsudin, F.

2014-01-01

Magnesium-based rechargeable batteries might be an interesting future alternative to lithium-based batteries since magnesium compounds are highly abundant in the earth and are environmental friendly. In this work, we have prepared polymethylmethacrylate (PMMA) based gel polymer electrolyte (GPE) films containing two different magnesium salts, which is magnesium triflate, Mg(CF 3 SO 3 ) 2 and magnesium perchlorate, Mg(ClO 4 ) 2 using solution casting technique . The ionic conductivity of both gel polymer electrolyte systems was evaluated using a.c impedance spectroscopy. Results show that at room temperature, GPE-Mg(CF 3 SO 3 ) 2 system exhibits the highest conductivity value at 1.27 × 10 −3 S cm −1 for the film containing 20 wt.% of Mg(CF 3 SO 3 ) 2 salt, while the highest conductivity value for the GPE-Mg(ClO 4 ) 2 system is 3.13 × 10 −3 S cm −1 for the film containing 15 wt.% of Mg(ClO 4 ) 2 salt. The conductivity-temperature studies of both GPE systems follow the Arrhenius behavior. The activation energies for ionic conduction were determined to be in the range of 0.18–0.26 eV. The transport numbers of magnesium ions in both GPE systems were evaluated using the combination of a.c impedance spectroscopy and d.c polarization techniques. The results obtained indicate that the charge carriers in the GPE films for both systems are predominantly due to ions

Controlling Radiation Degradation of Natural Polymers for Industrial and Agricultural application

International Nuclear Information System (INIS)

Hegazy, E.A.; AbdEl-Rehim, H

2008-01-01

Radiation induced degradation technology is a new and promising application of ionizing radiation to develop viscose, pulp, paper, food preservation, pharmaceutical production, and natural bioactive agents industries. Controlling the degree of degradation, uniform molecular weight distribution, saving achieved in the chemicals (used in conventional methods) on a cost basis, and environmentally friendly process are the beneficial effects of using radiation technology in these industries. However, for some development countries such technology is not economic. Therefore, a great effort should be done to reduce the cost required for such technologies. One of the principle factors for reducing the cost is achieving the degradation at low irradiation doses. The addition of some additives such as potassium per-sulfate (KPS), ammonium per-sulfate (APS), or H 2O2 to natural polymers such as chitosan and Na-alginate during irradiation process accelerates their degradation. The highest degradation rate of polysaccharides obtained when APS was used. The end product of irradiated chitosan, and Na-alginate may be used as food additive or benefited in agricultural purposes. The prepared crosslinked copolymers possessed high and fast swelling properties in simulated urine media and the swelling ratios of CMC-Na /PAAm gels in urine are acceptable for diaper application. (author)

Dye-Sensitized Solar Cells with Optimal Gel Electrolyte Using the Taguchi Design Method

Directory of Open Access Journals (Sweden)

Jenn-Kai Tsai

2013-01-01

Full Text Available The Taguchi method was adopted to determine the optimal gel electrolyte used in dye-sensitized solar cells (DSSCs. Since electrolyte is a very important factor in fabrication of high performance and long-term stability DSSCs, to find the optimal composition of gel electrolyte is desired. In this paper, the common ingredients used in the liquid electrolyte were chosen. The ingredients then mixed with cheap ionic liquids and poly(vinylidenefluoride-co-hexafluoropropylene (PVDF-HFP were added to form colloidal electrolyte (gel. The optimal composition of each materials in the gel electrolyte determined by Taguchi method consists of 0.03 M I2, 0.15 M KI, 0.6 M LiI, 0.5 M 4-tertbutylpyridine (TBP, and 10% PVDF-HFP dissolved in the acetonitrile and 3-methoxypropionitrile (MPN solution with volume ratio of 2 : 1. The short circuit current density of 14.11 mA/cm2, the conversion efficiency (η of 5.52%, and the lifetime of over 110 days were observed for the dye-sensitized solar cell assembled with optimal gel electrolyte. The lifetime increases 10 times when compared with the conventional dye-sensitized solar cell assembled with liquid electrolyte.

Mechanism of antioxidant interaction on polymer oxidation by thermal and radiation ageing

International Nuclear Information System (INIS)

Seguchi, Tadao; Tamura, Kiyotoshi; Shimada, Akihiko; Sugimoto, Masaki; Kudoh, Hisaaki

2012-01-01

The mechanism of polymer oxidation by radiation and thermal ageing was investigated for the life evaluation of cables installed in radiation environments. The antioxidant as a stabilizer was very effective for thermal oxidation with a small content in polymers, but was not effective for radiation oxidation. The ionizing radiation induced the oxidation to result in chain scission even at low temperature, because the free radicals were produced and the antioxidant could not stop the oxidation of radicals with the chain scission. A new mechanism of antioxidant effect for polymer oxidation was proposed. The effect of antioxidant was not the termination of free radicals in polymer chains such as peroxy radicals, but was the depression of initial radical formation in polymer chains by thermal activation. The antioxidant molecule was assumed to delocalize the activated energy in polymer chains by the Boltzmann statics (distribution) to result in decrease in the probability of radical formation at a given temperature. The interaction distance (delocalization volume) by one antioxidant molecule was estimated to be 5–10 nm by the radius of sphere in polymer matrix, though the value would depend on the chemical structure of antioxidant. - Highlights: ► Interaction of antioxidant on polymer oxidation is discussed for thermal and radiation ageings. ► Antioxidant is very effective for thermal oxidation, but not for radiation induced oxidation. ► Interaction of antioxidant is not the termination reaction of radicals on polymers. ► Antioxidant is supposed to reduce the provability of polymer radical formation by thermal activation. ► Mechanism of polymer oxidation may not be chain reaction via peroxy radical and hydro-peroxide.

The radiation induced degradation of polymers

International Nuclear Information System (INIS)

Wilski, H.

1987-01-01

A compilation was made of all data about the radiation stability of thermoplastic polymeric materials, published in the literature up to the end of 1985. From those experiments in which the irradiation was carried out in air half value doses (elongation) (= hvd) as a measure of radiation stability were extracted and compared on the basis of the chemical structure of the polymers, the chemical composition of the materials under test and the dose rate, respectively. The first result is that our knowledge of the radiation stability of polymers, if irradiated in air, is still very incomplete. On the other hand enough data were found for some polymers, to see that there is a region at low dose rates where the half value dose Dsub(e) increases with the dose rate (dD/dt) according to the equation Dsub(e)=Dsub(el).(dD/dt)sup(n). This seems to be the normal behavior. Values for the hvd at 1 Gy/h (in air) were found to lie between 1 and 500 kGy (with PTFE and PS at the respective ends of the scale), whereas n varied only between 0.1 and 0.4. The range of validity of the equation and the magnitude of the coefficients strongly depend on the chemical nature of the polymer and also on the kind and amount of the additives used. At dose rates in the neighborhood of 10 5 Gy/h the influence of the dose rate (and the atmosphere) disappears. (author)

Microenvironment around tumors and their radiation sensitivity. The possibility of molecular target for radiation sensitization

Energy Technology Data Exchange (ETDEWEB)

Akimoto, Tetsuo; Ishikawa, Hitoshi [Gunma Univ., Maebashi (Japan). School of Medicine; Mitsuhashi, Norio [Tokyo Women' s Medical Coll. (Japan)

2001-12-01

There have been scarce studies concerning the effect of microenvironment around tumors on their radiation sensitivity and this review describes the influence of environmental factors of cell adhesion, growth factors, cytokines, hypoxia and angiogenesis on the sensitivity and response to radiation and on the signal transduction to consider the possibility of molecular target for radiation sensitization. Cell-cell adhesion and cell-matrix interaction in response to radiation may have a role in inducing apoptotic process like anti-apoptotic or pro-apoptotic one. Growth factors and cytokines can affect the tumor response to radiation in more extent than p53 gene status since apoptosis induction is not always an indication of radiation sensitivity in many tumors clinically encountered. Radiation sensitivity is low in tumor cells under hypoxic conditions and it is important to know the relationship between those hypoxic cell response and angiogenesis by factors like HIF (hypoxia-inducible factor)-1. Molecular targets for radiation sensitization are now under development and both basic and clinical studies are important for future application of those sensitizing agents for the radiotherapy of tumors. (K.H.)

Microenvironment around tumors and their radiation sensitivity. The possibility of molecular target for radiation sensitization

International Nuclear Information System (INIS)

Akimoto, Tetsuo; Ishikawa, Hitoshi

2001-01-01

There have been scarce studies concerning the effect of microenvironment around tumors on their radiation sensitivity and this review describes the influence of environmental factors of cell adhesion, growth factors, cytokines, hypoxia and angiogenesis on the sensitivity and response to radiation and on the signal transduction to consider the possibility of molecular target for radiation sensitization. Cell-cell adhesion and cell-matrix interaction in response to radiation may have a role in inducing apoptotic process like anti-apoptotic or pro-apoptotic one. Growth factors and cytokines can affect the tumor response to radiation in more extent than p53 gene status since apoptosis induction is not always an indication of radiation sensitivity in many tumors clinically encountered. Radiation sensitivity is low in tumor cells under hypoxic conditions and it is important to know the relationship between those hypoxic cell response and angiogenesis by factors like HIF (hypoxia-inducible factor)-1. Molecular targets for radiation sensitization are now under development and both basic and clinical studies are important for future application of those sensitizing agents for the radiotherapy of tumors. (K.H.)

Unique proteomic signature for radiation sensitive patients; a comparative study between normo-sensitive and radiation sensitive breast cancer patients

Energy Technology Data Exchange (ETDEWEB)

Skiöld, Sara [Center for Radiation Protection Research, Department of Molecular Biosciences, The Wernner-Gren Institute, Stockholm University, Stockholm (Sweden); Azimzadeh, Omid [Institute of Radiation Biology, German Research Center for Environmental Health, Helmholtz Zentrum München (Germany); Merl-Pham, Juliane [Research Unit Protein Science, German Research Center for Environmental Health, Helmholtz Zentrum München, Neuherberg (Germany); Naslund, Ingemar; Wersall, Peter; Lidbrink, Elisabet [Division of Radiotherapy, Radiumhemmet, Karolinska University Hospital, Stockholm (Sweden); Tapio, Soile [Institute of Radiation Biology, German Research Center for Environmental Health, Helmholtz Zentrum München (Germany); Harms-Ringdahl, Mats [Center for Radiation Protection Research, Department of Molecular Biosciences, The Wernner-Gren Institute, Stockholm University, Stockholm (Sweden); Haghdoost, Siamak, E-mail: Siamak.Haghdoost@su.se [Center for Radiation Protection Research, Department of Molecular Biosciences, The Wernner-Gren Institute, Stockholm University, Stockholm (Sweden)

2015-06-15

Highlights: • The unique protein expression profiles were found that separate radiosensitive from normal sensitive breast cancer patients. • The oxidative stress response, coagulation properties and acute phase response suggested to be the hallmarks of radiation sensitivity. - Abstract: Radiation therapy is a cornerstone of modern cancer treatment. Understanding the mechanisms behind normal tissue sensitivity is essential in order to minimize adverse side effects and yet to prevent local cancer reoccurrence. The aim of this study was to identify biomarkers of radiation sensitivity to enable personalized cancer treatment. To investigate the mechanisms behind radiation sensitivity a pilot study was made where eight radiation-sensitive and nine normo-sensitive patients were selected from a cohort of 2914 breast cancer patients, based on acute tissue reactions after radiation therapy. Whole blood was sampled and irradiated in vitro with 0, 1, or 150 mGy followed by 3 h incubation at 37 °C. The leukocytes of the two groups were isolated, pooled and protein expression profiles were investigated using isotope-coded protein labeling method (ICPL). First, leukocytes from the in vitro irradiated whole blood from normo-sensitive and extremely sensitive patients were compared to the non-irradiated controls. To validate this first study a second ICPL analysis comparing only the non-irradiated samples was conducted. Both approaches showed unique proteomic signatures separating the two groups at the basal level and after doses of 1 and 150 mGy. Pathway analyses of both proteomic approaches suggest that oxidative stress response, coagulation properties and acute phase response are hallmarks of radiation sensitivity supporting our previous study on oxidative stress response. This investigation provides unique characteristics of radiation sensitivity essential for individualized radiation therapy.

Unique proteomic signature for radiation sensitive patients; a comparative study between normo-sensitive and radiation sensitive breast cancer patients

International Nuclear Information System (INIS)

Skiöld, Sara; Azimzadeh, Omid; Merl-Pham, Juliane; Naslund, Ingemar; Wersall, Peter; Lidbrink, Elisabet; Tapio, Soile; Harms-Ringdahl, Mats; Haghdoost, Siamak

2015-01-01

Highlights: • The unique protein expression profiles were found that separate radiosensitive from normal sensitive breast cancer patients. • The oxidative stress response, coagulation properties and acute phase response suggested to be the hallmarks of radiation sensitivity. - Abstract: Radiation therapy is a cornerstone of modern cancer treatment. Understanding the mechanisms behind normal tissue sensitivity is essential in order to minimize adverse side effects and yet to prevent local cancer reoccurrence. The aim of this study was to identify biomarkers of radiation sensitivity to enable personalized cancer treatment. To investigate the mechanisms behind radiation sensitivity a pilot study was made where eight radiation-sensitive and nine normo-sensitive patients were selected from a cohort of 2914 breast cancer patients, based on acute tissue reactions after radiation therapy. Whole blood was sampled and irradiated in vitro with 0, 1, or 150 mGy followed by 3 h incubation at 37 °C. The leukocytes of the two groups were isolated, pooled and protein expression profiles were investigated using isotope-coded protein labeling method (ICPL). First, leukocytes from the in vitro irradiated whole blood from normo-sensitive and extremely sensitive patients were compared to the non-irradiated controls. To validate this first study a second ICPL analysis comparing only the non-irradiated samples was conducted. Both approaches showed unique proteomic signatures separating the two groups at the basal level and after doses of 1 and 150 mGy. Pathway analyses of both proteomic approaches suggest that oxidative stress response, coagulation properties and acute phase response are hallmarks of radiation sensitivity supporting our previous study on oxidative stress response. This investigation provides unique characteristics of radiation sensitivity essential for individualized radiation therapy

Composite gel polymer electrolyte for lithium ion batteries

Science.gov (United States)

Naderi, Roya

Composite gel polymer electrolyte (CGPE) films, consisting of poly (vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) as the membrane, DMF and PC as solvent and plasticizing agent, mixture of charge modified TiO2 and SiO 2 nano particles as ionic conductors, and LiClO4+LiPF 6 as lithium salts were fabricated. Following the work done by Li et al., CGPE was coated on an O2-plasma treated trilayer polypropylene-polyethylene-polypropylene membrane separator using solution casting technique in order to improve the adhesive properties of gel polymer electrolyte to the separator membrane and its respective ionic conductivity due to decreasing the bulk resistance. In acidic CGPE with, the mixture of acid treated TiO2 and neutral SiO2 nano particles played the role of the charge modified nano fillers with enhanced hydroxyl groups. Likely, the mixture of neutral TiO 2 nano particles with basic SiO2 prepared through the hydrolization of tetraethyl orthosilicate (TEOS) provided a more basic environment due to the residues of NH4OH (Ammonium hydroxide) catalyst. The O2 plasma treated separator was coated with the solution of PVDF-HFP: modified nano fillers: Organic solvents with the mixture ratio of 0.1:0.01:1. After the evaporation of the organic solvents, the dried coated separator was soaked in PC-LiClO4+LiPF6 in EC: DMC:DEC (4:2:4 in volume) solution (300% wt. of PVDF-HFP) to form the final CGPE. Lim et al. has reported the enhanced ionic conductivity of 9.78*10-5 Scm-1 in an acidic composite polystyrene-Al2O3 solid electrolyte system with compared to that of basic and neutral in which the ionic conductivity undergoes an ion hopping process in solid interface rather than a segmental movement of ions through the plasticized polymer chain . Half-cells with graphite anode and Li metal as reference electrode were then assembled and the electrochemical measurements and morphology examinations were successfully carried out. Half cells demonstrated a considerable change in their

The place of radiation processing in polymer technology

International Nuclear Information System (INIS)

Du Plessis, T.A.

1978-01-01

A number of polymerisation processes initiated through radiation are discussed, among others the impregnation of wood with a monomer to form wood-polymer composites; radiation crosslinking of cable insulation; radiation degradation; radiation grafting of wool and textiles; and radiation sterilization of medical and pharmaceutical equipment. The last-named process is briefly compared to steam and to ethylene oxide sterlization

An Investigation of the Dose Distribution from LDR Ir-192 Wires in the Triangular Implants of the Paris System using Polymer Gel Dosimetry

Directory of Open Access Journals (Sweden)

Azizollah Rahimi

2010-12-01

Full Text Available Introduction: Polymer gels are modern dosimeters providing three dimensional dose distributions. These dosimeters can be used in brachytherapy in which the tumor dimension is relatively small and the dose gradient is high. In this study, the ability of the MAGICA polymer gel was investigated for assessing the absolute dose values as well as the dose distribution of low dose rate (LDR Ir-192 wires in interstitial brachytherapy based in triangular implants of the Paris system. Material and Methods: A suitable phantom was made from Perspex. Glass tubes were used as the external tubes for holding the Ir-192 wires in the phantom. The MAGICA polymer gel was made and placed in the phantom. The phantom and the calibration tubes were irradiated using LDR Ir-192 wires and a Co-60 teletherapy unit respectively. They were subsequently imaged using an MRI scanner. The R2 (=1/T2 maps were extracted from several sequential T2-weighted MRI images. The dose values resulting from the polymer gel measurements at the reference points were compared with those from the common calculation method at the same points. In addition, the isodose curves resulting from gel dosimetry were compared with those from a brachytherapy treatment planning system (Flexiplan. Results: The average of the dose values measured with the gel at the reference points was 62.75% higher than those calculated at the same points. Investigating the isodose curves revealed that the maximum distance to agreement (DTAmax between the isodoses resulting from the gel and those obtained from the treatment planning system was less than 3 mm at different dose levels. Discussion and Conclusion: Although the MAGICA gel indicates a higher absolute dose value than those calculated commonly, it can give the relative dose values accurately. Therefore, it can be recommended to be used for the assessment of dose distributions for the treatment of tissues as well as quality control of the treatment planning systems.

Simultaneous Thermal and Gamma Radiation Aging of Electrical Cable Polymers

Energy Technology Data Exchange (ETDEWEB)

Fifield, Leonard S.

2018-04-11

The polymers used for insulation in nuclear power plant electrical cables are susceptible to aging during long term operation. Elevated temperature is the primary contributor to changes in polymer structure that result loss of mechanical and electrical properties, but gamma radiation is also a significant source of degradation for polymers used within relevant plant locations. Despite many years of polymer degradation research, the combined effects of simultaneous exposure to thermal and radiation stress are not well understood. As nuclear operators contemplate and prepare for extended operations beyond initial license periods, a predictive understanding of exposure-based cable material degradation is becoming an increasingly important input to safety, licensing, operations and economic decisions. We are focusing on carefully-controlled simultaneous thermal and gamma radiation accelerating aging and characterization of the most common nuclear cable polymers to understand the relative contributions of temperature, time, dose and dose rate to changes in cable polymer material structure and properties. Improved understanding of cable performance in long term operation will help support continued sustainable nuclear power generation.

Future of radiation processing of polymers

International Nuclear Information System (INIS)

Chapiro, A.; Tabata, Y.; Stannett, V.; Dole, M.; Dobo, J.; Charlesby, A.

1990-01-01

The present development of radiation processing in the polymer field including well established technologies, with large scale productions and substantial markets, such as: crosslinking; curing of monomer-polymer formulations; sterilization of plastic supplies; are discussed. The manufacture of sophisticated devices with low volume production but large added value: electronic devices; resistors and several promising applications for which only small commercial productions are on stream today: chain degradation; polymerization; graft copolymerization, are reviewed. (author)

Tomotherapy dose distribution verification using MAGIC-f polymer gel dosimetry

International Nuclear Information System (INIS)

Pavoni, J. F.; Pike, T. L.; Snow, J.; DeWerd, L.; Baffa, O.

2012-01-01

Purpose: This paper presents the application of MAGIC-f gel in a three-dimensional dose distribution measurement and its ability to accurately measure the dose distribution from a tomotherapy unit. Methods: A prostate intensity-modulated radiation therapy (IMRT) irradiation was simulated in the gel phantom and the treatment was delivered by a TomoTherapy equipment. Dose distribution was evaluated by the R2 distribution measured in magnetic resonance imaging. Results: A high similarity was found by overlapping of isodoses of the dose distribution measured with the gel and expected by the treatment planning system (TPS). Another analysis was done by comparing the relative absorbed dose profiles in the measured and in the expected dose distributions extracted along indicated lines of the volume and the results were also in agreement. The gamma index analysis was also applied to the data and a high pass rate was achieved (88.4% for analysis using 3%/3 mm and of 96.5% using 4%/4 mm). The real three-dimensional analysis compared the dose-volume histograms measured for the planning volumes and expected by the treatment planning, being the results also in good agreement by the overlapping of the curves. Conclusions: These results show that MAGIC-f gel is a promise for tridimensional dose distribution measurements.

Tomotherapy dose distribution verification using MAGIC-f polymer gel dosimetry

Energy Technology Data Exchange (ETDEWEB)

Pavoni, J. F.; Pike, T. L.; Snow, J.; DeWerd, L.; Baffa, O. [Departamento de Fisica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto-Universidade de Sao Paulo, Av. Bandeirantes, 3900 - CEP 14040-901 - Bairro Monte Alegre - Ribeirao Preto, SP (Brazil); Medical Radiation Research Center, Department of Medical Physics, University of Wisconsin, 1111 Highland Avenue, B1002 WIMR, Madison, Wisconsin 53705-2275 (United States); Departamento de Fisica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto-Universidade de Sao Paulo, Av. Bandeirantes, 3900 - CEP 14040-901 - Bairro Monte Alegre - Ribeirao Preto, SP (Brazil)

2012-05-15

Purpose: This paper presents the application of MAGIC-f gel in a three-dimensional dose distribution measurement and its ability to accurately measure the dose distribution from a tomotherapy unit. Methods: A prostate intensity-modulated radiation therapy (IMRT) irradiation was simulated in the gel phantom and the treatment was delivered by a TomoTherapy equipment. Dose distribution was evaluated by the R2 distribution measured in magnetic resonance imaging. Results: A high similarity was found by overlapping of isodoses of the dose distribution measured with the gel and expected by the treatment planning system (TPS). Another analysis was done by comparing the relative absorbed dose profiles in the measured and in the expected dose distributions extracted along indicated lines of the volume and the results were also in agreement. The gamma index analysis was also applied to the data and a high pass rate was achieved (88.4% for analysis using 3%/3 mm and of 96.5% using 4%/4 mm). The real three-dimensional analysis compared the dose-volume histograms measured for the planning volumes and expected by the treatment planning, being the results also in good agreement by the overlapping of the curves. Conclusions: These results show that MAGIC-f gel is a promise for tridimensional dose distribution measurements.

In-situ radiation grafting of polymer films and degradation studies of monomers for applications in fuel cell membranes

Energy Technology Data Exchange (ETDEWEB)

Mitov, S.

2007-02-15

The present work consists of three parts which deal with the optimization of the properties of polymers finding application as proton exchange membranes in PEMFCs. The focus is the oxidative and photochemical stability of non-fluorinated polymer membranes, as well as the radiation-induced grafting of commercially available fluoropolymer films. The use of the ESR technique is common for the first two parts of the dissertation. ESR spectroscopy is the major method of study, because of its sensitivity and specificity for the detection of radical intermediates. It is a suitable spectroscopic technique to identify the nature of radiation generated radicals in organic polymers, and to monitor their concentration in-situ during the grafting process. The third part comprises the results and discussions of DFT calculations for non-fluorinated and fluorinated fragments.

Evaluation of the Accuracy of Polymer Gels for Determining Electron Dose Distributions in the Presence of Small Heterogeneities.

Science.gov (United States)

Asl, R Ghahraman; Nedaie, H A; Banaee, N

2017-12-01

The aim of this study is to evaluate the application and accuracy of polymer gels for determining electron dose distributions in the presence of small heterogeneities made of bone and air. Different cylindrical phantoms containing MAGIC (Methacrylic and Ascorbic acid in Gelatin Initiated by Copper) normoxic polymer gel were used under the slab phantoms during irradiation. MR images of the irradiated gel phantoms were obtained to determine their R2 (spin-spin) relaxation maps for conversion to absorbed dose. One- and 2-dimensional lateral dose profiles were acquired at depths of 1 and 4 cm for 8 and 15 MeV electron beams. The results were compared with the doses measured by a diode detector at the same positions. In addition, the dose distribution in the axial orientation was measured by the gel dosimeter. The slope and intercept for the R2 versus dose curve were 0.509 ± 0.002 Gy s and 4.581 ± 0.005 s, respectively. No significant variation in dose-R2 response was seen for the two electron energies within the applied dose ranges. The mean dose difference between the measured gel dose profiles was smaller than 3% compared to those measured by the diode detector. These results provide further demonstration that electron dose distributions are significantly altered in the presence of tissue inhomogeneities such as bone and air cavity and that MAGIC gel is a useful tool for 3-dimensional dose visualization and qualitative assessment of tissue inhomogeneity effects in electron beam dosimetry.

A Triphenylamine-Based Conjugated Polymer with Donor-π-Acceptor Architecture as Organic Sensitizer for Dye-Sensitized Solar Cells.

Science.gov (United States)

Zhang, Wei; Fang, Zhen; Su, Mingjuan; Saeys, Mark; Liu, Bin

2009-09-17

A conjugated polymer containing an electron donating backbone (triphenylamine) and an electron accepting side chain (cyanoacetic acid) with conjugated thiophene units as the linkers has been synthesized. Dye-sensitized solar cells (DSSCs) are fabricated utilizing this material as the dye sensitizer, resulting a typical power conversion efficiency of 3.39% under AM 1.5 G illumination, which represents the highest efficiency for polymer dye-sensitized DSSCs reported so far. The results show the good promise of conjugated polymers as sensitizers for DSSC applications. Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rheological and DSC study of sol-gel transition in aqueous dispersions of industrially important polymers and colloids

Energy Technology Data Exchange (ETDEWEB)

Nishinari, K. [Osaka City Univ. (Japan). Dept. of Food and Nutrition

1997-12-01

Gelation kinetics, mechanical spectra, thermal scanning rheology (TSR), and differential scanning calorimetry (DSC) in aqueous solutions of gelling polymers and colloids such as seaweed polysaccharides (agarose, carrageenans), microbial polysaccharides (gellan, curdlan), plant polysaccharides (methylcellulose), globular proteins (casein, glycinin, {beta}-conglycinin), fibrous proteins (gelatin, fibrin), and polyvinyl alcohol, which are related to foods, cosmetics, biomedical and pharmaceutical applications, are described. Some gelation processes at a constant temperature have been treated successfully by an equation of first order kinetics or by other modified equations, and the molecular mechanism of gel formation is discussed briefly. For water-soluble polymers, the criterion of the gel or sol based on the frequency dependence of storage and loss moduli gives valuable informations. TSR and DSC are complementary, and the combination of these methods has been proved to be useful. (orig.) 81 refs.

Sterilizing radiation effects on selected polymers

International Nuclear Information System (INIS)

Skiens, W.E.

1979-03-01

The mechanism of radiation effects and their industrial applications are discussed for the following classes of polymers: thermoplastics, thermosets, elastomers, films and fibers, and adhesives/coatings/potting compounds. 35 references, 3 tables

Gel nano-particulates against radioactivity

International Nuclear Information System (INIS)

Deroin, Ph.

2004-01-01

The Argonne research center (USA) has developed a 'super-gel' compound, a polymer close to those used in baby's diapers, which can reach a 90% efficiency in the radioactive decontamination of porous materials, like bricks or concrete. The contaminated materials are sprayed with a mixture of polymer gel and wetting agent with nano-particulates in suspension. Under the action of the wetting agent, radioactivity migrates from the pores to the gel and is trapped by the nano-particulates. The drying and recycling of the gel allows to reduce the volume of radioactive wastes. Short paper. (J.S.)

Actinic-radiation curable polymers prepared from a reactive polymer, halogenated cyclic anhydride and glycidyl ester

International Nuclear Information System (INIS)

Pastor, S.D.

1979-01-01

A novel class of photosensitive polymers are disclosed which are prepared by the reaction, preferably in the presence of a catalyst, of a reactive polymer, a halogenated cyclic anhydride and glycidyl ester of an alpha, beta-unsaturated carboxylic acid. These polymers are capable of undergoing vinyl-type polymerization when exposed to actinic radiation

Recent applications of ionic liquids in the sol-gel process for polymer-silica nanocomposites with ionic interfaces

Czech Academy of Sciences Publication Activity Database

Donato, K. Z.; Matějka, Libor; Mauler, R. S.; Donato, R. K.

2017-01-01

Roč. 1, č. 1 (2017), s. 1-25, č. článku 5. E-ISSN 2504-5377 Institutional support: RVO:61389013 Keywords : ionic liquids * sol-gel * ionic interfaces Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science

Controlling of degradation effects in radiation processing of polymers

International Nuclear Information System (INIS)

2009-05-01

The interest of Member States of the IAEA in introducing radiation technology into the polymer and plastics industry is growing. This publication summarizes a number of studies conducted in the framework of a coordinated research project (CRP) on controlling of degradation effects on polymers by radiation processing technologies. It reviews a variety of applications and details the most important results and achievements of the participating centres and laboratories during the course of the CRP. The publication is intended to be of use to scientists implementing the technology and managers of radiation processing facilities

Polymer gel measurement of dose homogeneity in the breast: comparing MLC intensity modulation with standard wedged delivery

International Nuclear Information System (INIS)

Love, P A; Evans, P M; Leach, M O; Webb, S

2003-01-01

Polymer gel dosimetry has been used to measure the radiotherapy dose homogeneity in a breast phantom for two different treatment methods. The first 'standard' method uses two tangential wedged fields while the second method has three static fields shaped by multileaf collimators (MLCs) in addition to the standard wedged fields to create intensity modulated fields. Gel dose distributions from the multileaf modulation treatment show an improved dose uniformity in comparison to the standard treatment with a decreased volume receiving doses over 105%

Preparation and properties of poly(ethylene oxide) gel filled polypropylene separators and their corresponding gel polymer electrolytes for Li-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Li Hao; Ma Xiaoting; Shi Junli; Yao Zhikan [Department of Polymer Science and Engineering, Engineering Center of Membrane and Water Treatment, Key Laboratory of Macromolecule Synthesis and Functionalization (EMC), Zhejiang University, Hangzhou 310027 (China); Zhu Baoku, E-mail: zhubk@zju.edu.c [Department of Polymer Science and Engineering, Engineering Center of Membrane and Water Treatment, Key Laboratory of Macromolecule Synthesis and Functionalization (EMC), Zhejiang University, Hangzhou 310027 (China); Zhu Liping [Department of Polymer Science and Engineering, Engineering Center of Membrane and Water Treatment, Key Laboratory of Macromolecule Synthesis and Functionalization (EMC), Zhejiang University, Hangzhou 310027 (China)

2011-02-15

Poly(ethylene oxide) (PEO) filled polypropylene separators (GFPSs) are designed by means of thermal cross-linking of entrapped poly(ethylene glycol) methyl ether acrylate (PEGMEA) and poly(ethylene glycol) diacrylate (PEGDA) as gel constituents. The intrinsic properties of GFPS and their corresponding gel polymer electrolytes (GPE) are characterized by DSC, SEM, contact angle and electrochemical methods. It is found the stability of liquid electrolyte uptake in GPE could be improved obviously. For the GPE prepared from GFPS with filled polyether content of 14.3 wt%, the ionic conductivity could reach 1.12 x 10{sup -3} S cm{sup -1} while the electrochemically stable window reach 5.0 V (vs. Li/Li{sup +}). These primary results show great promise of this simple method to prepare GPE for practical application in lithium ion batteries.

Preparation and properties of poly(ethylene oxide) gel filled polypropylene separators and their corresponding gel polymer electrolytes for Li-ion batteries

International Nuclear Information System (INIS)

Li Hao; Ma Xiaoting; Shi Junli; Yao Zhikan; Zhu Baoku; Zhu Liping

2011-01-01

Poly(ethylene oxide) (PEO) filled polypropylene separators (GFPSs) are designed by means of thermal cross-linking of entrapped poly(ethylene glycol) methyl ether acrylate (PEGMEA) and poly(ethylene glycol) diacrylate (PEGDA) as gel constituents. The intrinsic properties of GFPS and their corresponding gel polymer electrolytes (GPE) are characterized by DSC, SEM, contact angle and electrochemical methods. It is found the stability of liquid electrolyte uptake in GPE could be improved obviously. For the GPE prepared from GFPS with filled polyether content of 14.3 wt%, the ionic conductivity could reach 1.12 x 10 -3 S cm -1 while the electrochemically stable window reach 5.0 V (vs. Li/Li + ). These primary results show great promise of this simple method to prepare GPE for practical application in lithium ion batteries.

The effects of temperature on the radiation chemistry of polymers

International Nuclear Information System (INIS)

Hill, D.J.T.

1995-01-01

The effects of high energy radiation on polymers is dependent on a number of factors. One of the most important factors is the radiolysis temperature. This paper discusses the effects of the α-transition and the other secondary transitions, as well as the ceiling and melting temperatures, on the nature of the radiolysis reactions which occur for a number of polymers. Some implications of changes in the radiation chemistry of polymers with a change in the temperature are also considered. (author)

Viscoplastic fracture transition of a biopolymer gel.

Science.gov (United States)

Frieberg, Bradley R; Garatsa, Ray-Shimry; Jones, Ronald L; Bachert, John O; Crawshaw, Benjamin; Liu, X Michael; Chan, Edwin P

2018-06-13

Physical gels are swollen polymer networks consisting of transient crosslink junctions associated with hydrogen or ionic bonds. Unlike covalently crosslinked gels, these physical crosslinks are reversible thus enabling these materials to display highly tunable and dynamic mechanical properties. In this work, we study the polymer composition effects on the fracture behavior of a gelatin gel, which is a thermoreversible biopolymer gel consisting of denatured collagen chains bridging physical network junctions formed from triple helices. Below the critical volume fraction for chain entanglement, which we confirm via neutron scattering measurements, we find that the fracture behavior is consistent with a viscoplastic type process characterized by hydrodynamic friction of individual polymer chains through the polymer mesh to show that the enhancement in fracture scales inversely with the squared of the mesh size of the gelatin gel network. Above this critical volume fraction, the fracture process can be described by the Lake-Thomas theory that considers fracture as a chain scission process due to chain entanglements.

Environment-sensitive ion-track membranes

International Nuclear Information System (INIS)

Yoshida, Masaru

1996-01-01

Development of an environment-sensitive porous membrane from ion-track membranes may realize by combining the techniques of ion beam radiation and those of molecular designing and synthesis for intelligent materials. Now, the development of such membrane is progressing with an aim at selecting some specific substances and accurately control its pore size in response to any small environmental stimulus such as temperature change. The authors have been studying the molecular design, synthesis and functional expression of intelligent materials, which are called here as environment-sensitive gels. In this report, the outlines of the apparatus for the production of such porous membrane was described. An organic polymer membrane was irradiated with an ion beam and followed by chemical etching to make ion track pores. Scanning electron microscopic observation for the cross section of the membrane showed that the pore shape varies greatly depending on the ion nuclide used. The characteristics of newly produced porous membranes consisting of CR-30/A-ProDMe and polyethylene-telephtharate were investigated in respect of pore size change responding to temperature. These studies of design, synthesis and functions of such gels would enable to substitute artificial materials for the functions of human sensors. (M.N.). 54 refs

Polymer research at synchrotron radiation sources: symposium proceedings

International Nuclear Information System (INIS)

Russell, T.P.; Goland, A.N.

1985-01-01

The twenty-two papers are arranged into eleven sessions entitled: general overviews; time-resolved x-ray scattering; studies using fluorescence, ion-containing polymers; time-resolved x-ray scattering; novel applications of synchrotron radiation; phase transitions in polymers; x-ray diffraction on polymers; recent detector advances; complementary light, x-ray and neutron studies; and neutron scattering studies. Seven of the papers are processed separately; three of the remainder have been previously processed

Preparation and performance of a novel gel polymer electrolyte based on poly(vinylidene fluoride)/graphene separator for lithium ion battery

International Nuclear Information System (INIS)

Liu, Jiuqing; Wu, Xiufeng; He, Junying; Li, Jie; Lai, Yanqing

2017-01-01

Poly(vinylidenefluoride)/graphene (PVDF/graphene) gel polymer electrolyte is prepared via non-solvent induced phase separation (NIPS) technique for lithium ion battery application. The effect of graphene on the ion conductivity is investigated by AC impedance measurement. The relationship among the chemical structure, PVDF crystallinity, the graphene on macroporous formation and the ion conductivity are investigated. The results indicate that the graphene disperses homogenously in PVDF, and it also increases the porosity and decreases the crystallinity of the PVDF. At the same time, the unique structure increases the liquid uptake capability of PVDF/graphene polymer electrolyte. The ionic conductivity of the PVDF/graphene polymer electrolyte increases significantly from 1.85 mS cm"−"1 in pristine PVDF to 3.61 mS cm"−"1 with 0.002 wt% graphene. It is found that graphene not only increases the ionic conductivity but also markedly enhances the rate capability and the cycling performances of coin cell. This study shows that PVDF/graphene gel polymer electrolyte is a very promising material for lithium ion batteries.

Review on recent and advanced applications of monoliths and related porous polymer gels in micro-fluidic devices

International Nuclear Information System (INIS)

Vazquez, Mercedes; Paull, Brett

2010-01-01

This review critically summarises recent novel and advanced achievements in the application of monolithic materials and related porous polymer gels in micro-fluidic devices appearing within the literature over the period of the last 5 years (2005-2010). The range of monolithic materials has developed rapidly over the past decade, with a diverse and highly versatile class of materials now available, with each exhibiting distinct porosities, pore sizes, and a wide variety of surface functionalities. A major advantage of these materials is their ease of preparation in micro-fluidic channels by in situ polymerisation, leading to monolithic materials being increasingly utilised for a larger variety of purposes in micro-fluidic platforms. Applications of porous polymer monoliths, silica-based monoliths and related homogeneous porous polymer gels in the preparation of separation columns, ion-permeable membranes, preconcentrators, extractors, electrospray emitters, micro-valves, electrokinetic pumps, micro-reactors and micro-mixers in micro-fluidic devices are discussed herein. Procedures used in the preparation of monolithic materials in micro-channels, as well as some practical aspects of the micro-fluidic chip fabrication are addressed. Recent analytical/bioanalytical and catalytic applications of the final micro-fluidic devices incorporating monolithic materials are also reviewed.

Controlling of degradation effects in radiation processing of polymers. Second RCM report

International Nuclear Information System (INIS)

2005-08-01

The research and development works carried out by the participants of the CRP (Coordinated Research Project) dealt with natural polymers, synthetic polymers and new techniques for better understanding of radiation degradation of polymers. It includes progress in radiation degradation of polysaccharides from agricultural products (including sodium alginate, carrageenans, chitosan and gum acacia); use of radiation-degradation for doping of conductive polymers; controlling degradation processes in artificial joint implants, surface treatment of materials and food packaging; stabilizer additives for radiation environments; surface treatment of materials; and application of specialized analytical techniques (positron annihilation spectroscopy, ESR, RBS, ERDA, NMR/isotopic-labeling) to gain improved understanding of radiation degradation effects and mechanisms. Projects within the RCM group span the spectrum from fundamental studies through specific technological applications. Participants from Czech Republic, Spain and Turkey benefited from scientific collaboration with Bulgaria on PAS

PEGDA/PVdF/F127 gel type polymer electrolyte membranes for lithium secondary batteries

Energy Technology Data Exchange (ETDEWEB)

Wang, Yan-Jie; Kim, Dukjoon [Department of Chemical Engineering, Polymer Technology Institute, Sungkyunkwan University, Suwon, Kyunggi 440-746 (Korea)

2007-03-30

A novel porous gel polymer electrolyte (GPE) membrane based on poly(ethylene glycol) diacrylate (PEGDA), poly(vinylidene fluoride) (PVdF), and polyethylene oxide-co-polypropylene oxide-co-polyethylene oxide (PEO-PPO-PEO, F127) was fabricated by a phase inversion technique. The PEGDA cross-linking oligomer could be randomly mixed with unraveled PVdF polymer chains to form the interpenetrating polymer network (IPN) structure. Several experimental techniques including infrared (IR) spectra, differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and potentiostat/galvanostat were employed to investigate the characteristics of the polymer membranes. PEGDA and F127 influenced the porous size and structure. The mechanical strength and flexibility of the membrane were controlled by its composition. The membrane with the composition of PEGDA/PVdF/F127 (0/4/4) showed the highest electrolyte uptake of 152.6% and the maximum ionic conductivity of 2.0 x 10{sup -3} S cm{sup -1} at room temperature. All GPEs prepared in this study were electrochemically stable up to 4.5 V. (author)

Experimental determination of order in non-equilibrium solids using colloidal gels

International Nuclear Information System (INIS)

Gao Yongxiang; Kilfoil, Maria

2004-01-01

The idea of quantifying order in disordered systems has been introduced recently by Torquato and co-workers (2000 Phys. Rev. E 62 993-1001). We are interested in the application of this idea to measure structure in non-equilibrium systems. Here we focus on gels, using as a model system colloidal gels formed from hard spheres with polymer added to the systems to induce a controlled, weak attraction. To describe the structure of the gels we use real space imaging via confocal microscopy to obtain the full three-dimensional structure. We measure experimentally both translational order and bond angle correlations, defining a new (refined) translational order parameter that is sensitive to long range order in these non-random packings. This metric is also sensitive to anisotropy, which should be important in the many physical situations where an external force is present. The bond angle distribution shows coordinated organization. To give a clearer physical picture for gels, we compare the experimental data to computer generated hard sphere systems

A theory for fracture of polymeric gels

Science.gov (United States)

Mao, Yunwei; Anand, Lallit

2018-06-01

A polymeric gel is a cross-linked polymer network swollen with a solvent. If the concentration of the solvent or the deformation is increased to substantial levels, especially in the presence of flaws, then the gel may rupture. Although various theoretical aspects of coupling of fluid permeation with large deformation of polymeric gels are reasonably well-understood and modeled in the literature, the understanding and modeling of the effects of fluid diffusion on the damage and fracture of polymeric gels is still in its infancy. In this paper we formulate a thermodynamically-consistent theory for fracture of polymeric gels - a theory which accounts for the coupled effects of fluid diffusion, large deformations, damage, and also the gradient effects of damage. The particular constitutive equations for fracture of a gel proposed in our paper, contain two essential new ingredients: (i) Our constitutive equation for the change in free energy of a polymer network accounts for not only changes in the entropy, but also changes in the internal energy due the stretching of the Kuhn segments of the polymer chains in the network. (ii) The damage and failure of the polymer network is taken to occur by chain-scission, a process which is driven by the changes in the internal energy of the stretched polymer chains in the network, and not directly by changes in the configurational entropy of the polymer chains. The theory developed in this paper is numerically implemented in an open-source finite element code MOOSE, by writing our own application. Using this simulation capability we report on our study of the fracture of a polymeric gel, and some interesting phenomena which show the importance of the diffusion of the fluid on fracture response of the gel are highlighted.

Dosimetry Evolution in Teletherapy: Polimer Gel

Science.gov (United States)

Hamann, J. H.; Peixoto, J. G. P.

2018-03-01

Polymer gels evolution and chemical composition used in dosimetry. Type Composition First gels Folin’s Phenol or Gallic Acid Polymer Gel Agarose and N,N’-methylene-bis-acrylamide BANANA Bis, acrylamide, nitrous oxide and agarose BANG-1TM Bis, acrylamide, nitrogen and gelatin BANG-2TM Bis, acrylic acid, sodium hydroxide, nitrogen and gelatin BANG-3TM Bis, methacrylate acid, sodium hydroxide, nitrogen and gelatin MAGIC Methacrylate acid, ascorbic acid, gelatin and copper sulphate

Radiation synthesis and characterization of network structure of natural/synthetic double-network superabsorbent polymers

International Nuclear Information System (INIS)

Sen, M.; Hayrabolulu, H.

2011-01-01

Complete text of publication follows. Superabsorbent polymers (SAPs) are moderately cross linked, 3-D, hydrophilic network polymers that can absorb and conserve considerable amounts of aqueous fluids even under certain heat or pressure. Because of the unique properties superior to conventional absorbents, SAPs have found potential application in many fields such as hygienic products, disposable diapers, horticulture, gel actuators, drug-delivery systems, as well as water-blocking tapes coal dewatering, water managing materials for the renewal of arid and desert environment, etc. In recent years, naturally available resources, such as polysaccharides have drawn considerable attention for the preparation of SAPs. Since the mechanical properties of polysaccharide based natural polymers are low, researchers have mostly focused on natural/synthetic polymer/monomer mixtures to obtain novel SAPs. The aim of this study is to synthesize and characterization of network structure of novel double-network (DN) hydrogels as a SAP. Hydrogels with high mechanical strength have been prepared by radiation induced polymerization and crosslink of acrylic acid sodium salt in the presence of natural polymer locust bean gum. Liquid retention capacities and absorbency under load (AUL) analysis of synthesized SAPs was performed at different temperatures in water and synthetic urine solution, in order to determine their SAP character. For the characterization of network structure of the semi-IPN hydrogels, the average molecular weight between cross links (M c ) were evaluated by using uniaxial compression and oscillatory dynamical mechanical analyses and the advantage and disadvantage of these two technique for the characterization of network structures were compared.

Polymer research at synchrotron radiation sources: symposium proceedings

Energy Technology Data Exchange (ETDEWEB)

Russell, T.P.; Goland, A.N. (eds.)

1985-01-01

The twenty-two papers are arranged into eleven sessions entitled: general overviews; time-resolved x-ray scattering; studies using fluorescence, ion-containing polymers; time-resolved x-ray scattering; novel applications of synchrotron radiation; phase transitions in polymers; x-ray diffraction on polymers; recent detector advances; complementary light, x-ray and neutron studies; and neutron scattering studies. Seven of the papers are processed separately; three of the remainder have been previously processed. (DLC)

Influences of poly (vinyl alcohol molecular weight and carbon nanotubes on radiation crosslinking shape memory polymers

Directory of Open Access Journals (Sweden)

Aamer A.M. Alfayyadh

2017-06-01

Full Text Available Polyvinyl alcohol (PVA of two molecular weights was used to prepare shape memory polymers based on chemical-crosslinking by glutaraldehyde. The chemical-crosslinking was done in the presence of 2-carboxyethyl acrylate oligomers (CEA and nano-filler [multi-wall carbon nanotubes (MWCNT and functionalized carbon nanotubes (MWCNT-NH2] followed by radiation-induced crosslinking. The analysis of the material revealed an increase in the gel fraction and a significant reduction in swelling of the nanocomposite material that was crosslinked with both glutaraldehyde and ionizing radiation. The radiation crosslinked nanocomposites demonstrated approximately a 90% gelation over a range of 50–300 kGy irradiation doses. The scanning electron microscopy (SEM analysis showed a homogeneous distribution of nanocomposites in the composite matrix. The thermal properties of radiation crosslinked (PVA/CEA and (PVA-CEA-nano-fillers were investigated by a thermogravimetric analysis (TGA. The mechanical properties were examined via dynamic mechanical analysis (DMA which showed significant variation because of the addition of nanocomposites. This radiation crosslinked materials show good shape memory behavior that may be useful in many applications based on the range of temperatures at which Tan δ appears.

Gel electrolytes based on poly(acrylonitrile)/sulpholane with hybrid TiO2/SiO2 filler for advanced lithium polymer batteries

International Nuclear Information System (INIS)

Kurc, Beata

2014-01-01

Highlights: • Paper describes properties of gel electrolyte based on PAN with TMS and TiO 2 -SiO 2 . • The TiO 2 -SiO 2 oxide composite was precipitated in the emulsion system and used as the fillers. • The capacity of the graphite anode depends on the current rate and the amount of TiO 2 -SiO 2 . • For PE3 electrolyte was obtained practical capacity more than 90% of the theoretical capacity. - Abstract: This paper describes the synthesis and properties of a new type of ceramic fillers for composite polymer gel electrolytes. Hybrid TiO 2 -SiO 2 ceramic powders have been obtained by co-precipitation from titanium(IV) sulfate solution using sodium silicate as the precipitating agent. The resulting submicron-size powders have been applied as fillers for composite polymer gel electrolytes for Li-ion batteries based on polyacrylonitrile (PAN) membranes. The powders and gel electrolytes have been examined structurally and electrochemically, showing favorable properties in terms of electrolyte uptake and electrochemical characteristics in Li-ion cells

Electrochemical impedimetric sensor based on molecularly imprinted polymers/sol-gel chemistry for methidathion organophosphorous insecticide recognition.

Science.gov (United States)

Bakas, Idriss; Hayat, Akhtar; Piletsky, Sergey; Piletska, Elena; Chehimi, Mohamed M; Noguer, Thierry; Rouillon, Régis

2014-12-01

We report here a novel method to detect methidathion organophosphorous insecticides. The sensing platform was architected by the combination of molecularly imprinted polymers and sol-gel technique on inexpensive, portable and disposable screen printed carbon electrodes. Electrochemical impedimetric detection technique was employed to perform the label free detection of the target analyte on the designed MIP/sol-gel integrated platform. The selection of the target specific monomer by electrochemical impedimetric methods was consistent with the results obtained by the computational modelling method. The prepared electrochemical MIP/sol-gel based sensor exhibited a high recognition capability toward methidathion, as well as a broad linear range and a low detection limit under the optimized conditions. Satisfactory results were also obtained for the methidathion determination in waste water samples. Copyright © 2014 Elsevier B.V. All rights reserved.

A rechargeable Li-CO{sub 2} battery with a gel polymer electrolyte

Energy Technology Data Exchange (ETDEWEB)

Li, Chao; Guo, Ziyang; Yang, Bingchang; Liu, Yao; Wang, Yonggang; Xia, Yongyao [Dept. of Chemistry and Shanghai Key Lab. of Molecular Catalysis and Innovative Materials, Inst. of New Energy, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Fudan Univ. (China)

2017-07-24

The utilization of CO{sub 2} in Li-CO{sub 2} batteries is attracting extensive attention. However, the poor rechargeability and low applied current density have remained the Achilles' heel of this energy device. The gel polymer electrolyte (GPE), which is composed of a polymer matrix filled with tetraglyme-based liquid electrolyte, was used to fabricate a rechargeable Li-CO{sub 2} battery with a carbon nanotube-based gas electrode. The discharge product of Li{sub 2}CO{sub 3} formed in the GPE-based Li-CO{sub 2} battery exhibits a particle-shaped morphology with poor crystallinity, which is different from the contiguous polymer-like and crystalline discharge product in conventional Li-CO{sub 2} battery using a liquid electrolyte. Accordingly, the GPE-based battery shows much improved electrochemical performance. The achieved cycle life (60 cycles) and rate capability (maximum applied current density of 500 mA g{sup -1}) are much higher than most of previous reports, which points a new way to develop high-performance Li-CO{sub 2} batteries. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

SEM studies of the structure of the gels prepared from untreated and radiation modified potato starch

International Nuclear Information System (INIS)

Cieśla, Krystyna; Sartowska, Bożena; Królak, Edward

2015-01-01

Potato starch was irradiated with a 60 Co gamma rays using doses of 5, 10, 20 and 30 kGy. Gels containing ca. 9.1% of starch were prepared by heating the starch suspensions in the heating chamber stabilized at 100 °C. Four procedures were applied for preparation of the samples in regard to SEM studies and the ability to observe the radiation effect by SEM was assessed for each method. Differences were observed between the SEM images recorded for the non-irradiated samples prepared using all the methods, and those irradiated. Images of the non-irradiated gels indicate generally a honey-comb structure, while smooth areas but with oriented fractures has appeared after irradiation. Modification of gel structure corresponds to the applied dose. The results were related to the process of gel formation (as observed by means of the hot stage microscope) to decrease in swelling power of the irradiated starch and to decreased viscosity of the resulting gels. It can be concluded that the differences in structural properties of gels shown by SEM result probably due to the better homogenization of the gels formed after radiation induced degradation. - Highlights: • Four procedures of the preservation of starch gels for SEM studies were applied. • The ability to observe the radiation effect by SEM was assessed for each method. • Dose dependent changes in the gel structure were discovered. • It was related to decrease in the swelling power and decreased viscosity of the gels. • A hot-stage microscope was applied in order to follow the gelatinization process

Dose characterization of the new Bebig IsoSeed'' (registered) I25.S17 using polymer gel and MRI

Energy Technology Data Exchange (ETDEWEB)

Pantelis, Evaggelos [Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece)]. E-mail: vpantelis@phys.uoa.gr; Baltas, Dimos [Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece): Department of Medical Physics and Engineering, Strahlenklinik, Klinikum Offenbach, 63069 Offenbach (Germany); Georgiou, Evaggelos [Medical Physics Department, University of Athens, 75 Mikras Asias, 115 27 Athens (Greece); Karaiskos, Pantelis [Medical Physics Department, University of Athens, 75 Mikras Asias, 115 27 Athens (Greece): Medical Physics Department, Hygeia Hospital, Kiffisias Avenue and 4 Erythrou Stavrou, Marousi, 151 23 Athens (Greece); Lymperopoulou, Georgia [Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece); Papagiannis, Panagiotis [Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece); Sakelliou, Loukas [Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece); Seimenis, Ioannis [Philips Hellas Medical Systems, 44 Kifissias Ave., Maroussi 151 25, Athens (Greece); Stilliaris, Efstathios [Nuclear and Particle Physics Section, Physics Department, University of Athens, Panepistimioupolis, Ilisia, 157 71 Athens (Greece): Institute of Accelerating Systems and Applications (IASA), P.O. Box 17214, GR-10024, Athens (Greece)

2006-12-20

A new, molybdenum core, {sup 125}I interstitial brachytherapy seed is marketed by Bebig GmbH (IsoSeed'' (registered) I25.S17) and our group has performed its Dosimetric characterization using Monte Carlo (MC) simulation and Thermoluminescence dosimetry (TLD) as recommended by the AAPM TG-43U1 prior to the clinical implementation of new low-energy seeds. This work presents the results of a supplementary experimental dosimetry study performed using PABIG polymer gel and Magnetic Resonance Imaging (MRI). One new I25.S17 seed and a commercially available, gold core, Bebig IsoSeed'' (registered) I25.S06 {sup 125}I seed were positioned at two different locations in a vial filled with water equivalent, PABIG-polymer gel. The gel with the sources in place was MR scanned in 3D at various time intervals after seed placement using a time efficient, 3D, dual echo Turbo Spin Echo pulse sequence. The consensus dosimetry parameters published in the TG-43U1 for the I25.S06 seed were used to derive the gel response calibration curve for each scanning session. The calibration data were then used to provide dosimetry results for the new I25.S17 seed. Experimental results for the new seed in the form of dose distributions as well as dosimetric quantities in the prevalent TG-43 dosimetric formalism were found to be in close agreement with corresponding MC and TLD results. This finding suggests that the polymer gel-MRI method could at least play a supplementary role to TLD dosimetry in the dose characterization of low energy/low dose rate brachytherapy sources, especially in view of its potential for measurements with a fine spatial resolution down to short distances which are inhibitory to conventional experimental techniques.

Use of radiation-induced polymers in cement slurries

International Nuclear Information System (INIS)

Knight, B.L.; Rhudy, J.S.; Gogarty, W.B.

1976-01-01

Water loss from cement slurries is reduced by incorporating within a cement slurry a polymer obtained as a product of radiation-induced polymerization of acrylamide and/or methacrylamide and acrylic acid, methacrylic acid, and/or alkali metal salts thereof. The polymerization is preferably carried out in 10-60 percent aqueous monomer solution with gamma radiation. The aqueous monomer solution preferably contains 25-99 percent acrylamide and 75-1 percent sodium acrylate. The polymer can be present in concentration of about 0.001 to about 3.0 weight percent, based on the aqueous phase of the slurry

Absorbed energy for radiation crosslinking in stabilized PE systems

International Nuclear Information System (INIS)

Novakovic, Lj.; Gal, O.; Charlesby, A.

1990-01-01

A quantitative consideration on the absorbed energy consumption in various γ-irradiated polyethylene systems is given. On the base of the increased gel dose values for the PE systems containing antioxidant, relative to the gel doses for the pure polymers, the surplus of the absorbed energy due to the presence of the particular antioxidant is calculated. The increasing of the energy consumption in the stabilized systems depends on both the type and the content of the basic polymer. The surplus in the absorbed energy decreases with the radiation dose increasing, reflecting both the diminishing of the antioxidant concentration in the irradiating PE systems and the crosslinking level. The findings can be of interest in the estimation of the absorbed doses for the specific radiation crosslinking processes. (author)