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Radiation techniques are used to modify the physical, chemical and biological properties of polymers. This induces crosslinking and degradation reactions of polymers by utilizing radicals generated through ionizing radiation. However, oxidation products (such as carbonyl) can be formed because oxidation occurs by chain scission in the presence of oxygen. Herein, we demonstrate the gamma-ray irradiation-induced oxidation with and without fluorine using polyethylene, polyvinylidene fluoride and polytetrafluoroethylene under the same conditions. In this study, changes in element-content and chemical-bond structures were analyzed before and after gamma-ray irradiation under air atmosphere. As a result, polytetrafluo-roethylene showed less oxidation and excellent thermal properties after the absorbed dose of 500 kGy. This can be attributed to the generation of stable perfluoroalkylperoxy radicals after gamma ray irradiation in the PTFE structure containing only CF2 groups, thereby hindering the oxidation reaction. [ABSTRACT FROM AUTHOR]

The outstanding electrical, mechanical, and thermal properties of carbon nanotubes (CNTs) make them promising materials for a wide range of applications. Numerous theoretical and experimental studies on the diameter-dependent properties of single-walled carbon nanotubes (SW-CNTs) exist. The incorporation of carbon nanotubes into commercial polymers can alter the properties of both materials. Herein, we demonstrate polystyrene/SW-CNT composites with different diameters to check property changes, including radiation-protective characteristics under various doses of gamma radiation. The intrinsic glassy state of polystyrene disappeared owing to the introduction of SW-CNTs into the polymer-polymer chain. In addition, when 1.3 nm diameter SW-CNTs were introduced, the Fourier-transform infrared spectroscopy peaks for alkyl aryl ethers were observed at 10–60 kGy of gamma irradiation. In this study, the different phenomena that occur when polystyrene/SW-CNT composites are formed with different SW-CNT diameters (0.78 nm and 1.3 nm) were investigated via systematic analyses. [ABSTRACT FROM AUTHOR]

In this work, a unique one-pot green synthesis technique that utilizes high energy gamma-irradiation technology was successfully designed to fabricate a stable, highly-porous Prussian blue (PB)/polyvinylpyrrolidone (PVP)/reduced graphene oxide (rGO) aerogel (PB@PVP/rGO) with a 3D-network structure, low density, and high mechanical strength. In this synthesis process, PB nanoparticles were generated in situ and then homogenously distributed and entrapped within the PVP/rGO aerogel. The synthesized aerogel exhibited (i) a three-dimensional microporous architecture consisting of an interconnected network structure with an ultra-low density of 0.0273 g cm−3; (ii) remarkable swelling ability in the presence of water at low pH levels; and (iii) strong mechanical stability, leading to excellent deformability without cracks or the loss of structural integrity, due to the double-network structure of the PB@PVP/rGO aerogel and the crosslinking between the stiff GO sheets and the flexible PVP chains. The hydrophilic PB@PVP/rGO aerogel demonstrated the rapid adsorption of Cs+ ions and MB dye due to capillary action; based on the Langmuir model it demonstrated a maximum adsorption capacity of 143.88 and 44.73 mg g−1 for Cs+ and MB, respectively. The PB@PVP/rGO aerogel also exhibited outstanding oil absorption capacity, which we attribute to its highly interconnected porous structure and the presence of oleophilic rGO. The excellent adsorption properties coupling with the unique structural features of this PB@PVP/rGO aerogel make it a promising adsorbent for oil spills and for the removal of environmental pollutants such as Cs+ and MB in water. [ABSTRACT FROM AUTHOR]

As a robust radioanalytical method for tracking carbonaceous particulates in vivo, polycyclic aromatic hydrocarbons from diesel exhaust were labeled with a radioactive-iodine-tagged pyrene analogue. Single-photon emission computed tomography and biodistribution studies showed high uptake and slow clearance of this matter in the respiratory system, which may underlie its severe toxicity. [ABSTRACT FROM AUTHOR]

To assess the risk posed by a toxic chemical to human health, it is essential to quantify its uptake in a living subject. This study aims to investigate the biological distribution of inhaled polyhexamethylene guanidine (PHMG) aerosol particle, which is known to cause severe pulmonary damage. By labeling with indium-111 ( 111 In), we quantified the uptake of PHMG for up to 7 days after inhalation exposure in rats. The data demonstrate that PHMG is only slowly cleared, with approximately 74% of inhaled particles persisting in the lungs after 168 h. Approximately 5.3% of inhaled particles were also translocated to the liver after 168 h, although the level of redistribution to other tissues, including the kidneys and spleen, was minimal. These observations suggest that large uptake and slow clearance may underlie the fatal inhalation toxicity of PHMG in humans. [ABSTRACT FROM AUTHOR]

We herein report a new bioremediation method using a radiation-resistant bacterium. Biogenic gold nanomaterial-containing Deinococcus radiodurans R1 showed excellent capability for the removal of radioactive iodine (＞99%) in several aqueous solutions. These observations demonstrated that our remediation system would be efficiently applied to the treatment of radioactive wastes. [ABSTRACT FROM AUTHOR]

The scission rates of polystyrene and fluorinated polystyrene irradiated in an irradiation facility with Co-60 γ-rays were determined using molecular dynamics simulation and gel permeation chromatography (GPC) molecular weight distributions. The prediction was based on the assumption that γ-ray energy is transferred to the initial velocity of the primary knock-on atom. We employed a molecular dynamics simulation procedure to compute the changes in bond length between the connections for selected values of the absorbed dose and compared the calculated values with measurements made on the irradiated samples. The samples were exposed to four different absorbed doses of 25, 50, 75, and 100 kGy. The scission process and scission ratio were simulated with LAMMPS with ReaxFF potential for each bond, and we compared the simulation results with the experimental data especially measuring average molecular weight to evaluate the effect of fluorination on radiation enhancement. [ABSTRACT FROM AUTHOR]

This paper describes a novel chromatographic method for efficient removal of anionic dyes from aqueous solutions. Chitosan-coated Fe3O4 nanoparticles can easily be immobilized on a dextran gel column. Single elution of Evans Blue (EB) solution to the nanoadsorbent-incorporated columns provides high removal efficiency with a maximum adsorption capacity of 243.9 mg/g. We also investigated the influence of initial concentration and solution pH on the removal efficiency of EB. The electrostatic interaction between the adsorbent surface and negatively charged sulfate groups on EB molecules promotes the efficient adsorption of dyes. The equilibrium data matched well with the Langmuir isotherm model, which indicated monolayer dye adsorption onto the adsorbent surface. To extend the application of the current method, we performed further adsorption experiments using other anionic dyes of different colors (Cy5.5, Acid Yellow 25, Acid Green 25, and Acid Red 1). All of these molecules can efficiently be captured under continuous flow conditions, with higher removal efficiency obtained with more negatively charged dyes. These findings clearly demonstrate that the present approach is a useful method for the removal of anionic dye contaminants in aqueous media by adsorption. [ABSTRACT FROM AUTHOR]

In this study, biodegradable poly(L-lactide-co-ε-caprolactone) (PLCL) and poly(L-co-d,l lactide) (PLDLA) were evaluated using Geant4 (G4EmStandardPhysics_option4) for damage simulation, in order to predict the safety of these biodegradable polymers against gamma ray sterilization. In the PLCL damage model, both chain scission and crosslinking reactions appear to occur at a radiation dose in the range 0-200 kGy, but the chain cleavage reaction is expected to be relatively dominant at high irradiation doses above 500 kGy. On the other hand, the PLDLA damage model predicted that the chain cleavage reaction would prevail at the total irradiation dose (25-500 kGy). To verify the simulation results, the physicochemical changes in the irradiated PLCL and PLDLA films were characterized by GPC (gel permeation chromatography), ATR-FTIR (attenuated total reflection Fourier transform infrared), and DSC (difference scanning calorimetry) analyses. The Geant4 simulation curve for the radiation-induced damage to the molecular weight was consistent with the experimentally obtained results. These results imply that the pre-simulation study can be useful for predicting the optimal irradiation dose and ensuring material safety, particularly for implanted biodegradable materials in radiation processing.

Increasing concerns regarding the adverse effects of radioactive iodine waste have inspired the development of a highly efficient and sustainable desalination process for the treatment of radioactive iodine-contaminated water. Because of the high affinity of silver towards iodine species, silver nanoparticles immobilized on a cellulose acetate membrane (Ag-CAM) and biogenic silver nanoparticles containing the radiation-resistant bacterium Deinococcus radiodurans (Ag-DR) were developed and investigated for desalination performance in removing radioactive iodines from water. A simple filtration of radioactive iodine using Ag-CAM under continuous in-flow conditions (approximately 1.5 mL/s) provided an excellent removal efficiency (>99%) as well as iodide anion-selectivity. In the bioremediation study, the radioactive iodine was rapidly captured by Ag-DR in the presence of high concentration of competing anions in a short time. The results from both procedures can be visualized by using single-photon emission computed tomography (SPECT) scanning. This work presents a promising desalination method for the removal of radioactive iodine and a practical application model for remediating radioelement-contaminated waters.

Here, we demonstrate a detail protocol for the preparation of nanomaterials-embedded composite membranes and its application to the efficient and ion-selective removal of radioactive iodines. By using citrate-stabilized gold nanoparticles (mean diameter: 13 nm) and cellulose acetate membranes, gold nanoparticle-embedded cellulose acetate membranes (Au-CAM) have easily been fabricated. The nano-adsorbents on Au-CAM were highly stable in the presence of high concentration of inorganic salts and organic molecules. The iodide ions in aqueous solutions could rapidly be captured by this engineered membrane. Through a filtration process using an Au-CAM containing filter unit, excellent removal efficiency (>99%) as well as ion-selective desalination result was achieved in a short time. Moreover, Au-CAM provided good reusability without significant decrease of its performances. These results suggested that the present technology using the engineered hybrid membrane will be a promising process for the large-scale decontamination of radioactive iodine from liquid wastes.

There has been worldwide attention on the efficient removal of radioactive iodine, because it is commonly released in nuclear plant accidents. Increasing concerns on environmental problems due to the radioactive iodine are leading us to develop stable and sustainable technology for remediation of radioelement contaminants. In this work, we report a highly efficient chromatographic method for specific and rapid capture of radioactive iodine. The gold nanoparticles immobilized dextran gel columns showed excellent removal capabilities of radioactive iodine in various conditions. These results suggested that our platform technology can be a promising method for the desalination of radioactive iodines in water.

Here, we demonstrate a detailed protocol for the radiosynthesis of a 125 I-labeled azide prosthetic group and its application to the efficient radiolabeling of DBCO-group-functionalized gold nanoparticles using a copper-free click reaction. Radioiodination of the stannylated precursor (2) was carried out by using [ 125 I]NaI and chloramine T as an oxidant at room temperature for 15 min. After HPLC purification of the crude product, the purified 125 I-labeled azide (1) was obtained with high radiochemical yield (75 ± 10%, n = 8) and excellent radiochemical purity (>99%). For the synthesis of radiolabeled 13-nm-sized gold nanoparticles, the DBCO-functionalized gold nanoparticles (3) were prepared by using a thiolated polyethylene glycol polymer. A copper-free click reaction between 1 and 3 gave the 125 I-labeled gold nanoparticles (4) with more than 95% of radiochemical yield as determined by radio-thin-layer chromatography (radio-TLC). These results clearly indicate that the present radiolabeling method using a strain-promoted copper-free click reaction will be useful for the efficient and convenient radiolabeling of DBCO-group-containing nanomaterials.