Homogeneous Irradiation Research Articles

(BeDABCO)2Pd2Cl6 (1‐benzyl‐4‐aza‐1‐azoniabicyclo[2.2.2]octane chloride) as a highly active catalytic system for the Stille cross‐coupling reaction under microwave irradiation

An efficient catalytic system using (BeDABCO)2Pd2Cl6 was developed for the Stille cross‐coupling reaction. The substituted biaryls were produced in excellent yields in short reaction times using a catalytic amount of this catalyst in DMF at 120 °C. The ionic character of homogeneous catalyst and microwave irradiation and also DMF as microwave‐active polar solvent gave higher yields and shorter reaction times than conventional heating. Benzyl DABCO as an efficient ligand and also a quaternary ammonium salt had an efficient stabilizing effect on the Pd(0) species. Copyright © 2013 John Wiley & Sons, Ltd.

Bystander effects in tumor-free and tumor-bearing rat brains following irradiation by synchrotron X-rays

Purpose: Synchrotron microbeam radiation therapy (MRT) is a radiosurgery concept in the preclinical stage, developed mainly for brain tumor treatment. Experimental studies suggest that with MRT a better therapeutic index can be obtained than with homogenous field radiotherapy, but the underlying cellular mechanisms need further understanding. The aim of this study was to investigate the dynamics of radiation-induced bystander effects (RIBE) in rats after exposing one brain hemisphere to either MRT or homogenous synchrotron radiation (HSR).Materials and methods: Healthy and tumor-bearing Wistar rats were exposed to doses of 17.5, 35, 70 or 350 Gy, applied either as MRT or HSR to the right cerebral hemisphere. Rats were euthanized at 4, 8 and 12 hours after irradiation to assess the release of bystander signals. Brains and urinary bladders were dissected, and explants for bystander clonogenic reporter assays were set up.Results: Clonogenic survival showed that RIBE occurred in both the non-irradiated brain hemisphere and in bladder of normal and tumor-bearing rats, while the irradiated hemisphere showed the direct effects of radiation.Conclusion: The RIBE observed in our reporter cells shows that both MRT and HSR yield a demonstrable abscopal effect after high doses of irradiation; presumably as part of a systemic response.

Fully covariant radiation force on a polarizable particle

The electromagnetic force on a polarizable particle is calculated in a covariant framework. Local equilibrium temperatures for the electromagnetic field and the particle's dipole moment are assumed, using a relativistic formulation of the fluctuation–dissipation theorem. Two examples illustrate radiative friction forces: a particle moving through a homogeneous radiation background and above a planar interface. Previous results for arbitrary relative velocities are recovered in a compact way.

Creation of Adhesive Force between Laminated Sheets of Polyurethane (PU) and Polytetrafluoruethylene (PTFE) by Homogeneous Low Energy Electron Beam Irradiation Prior to Hot-Press for Bio-Adaptable Application

Bio-adaptable 2-layer polyurethane/polytetrafluoroethylene (PU/PTFE) laminated sheets were prepared by a new adhesion method, a double-step treatment consisting of: (1) applying low dose <0.65MGy homogeneous low energy electron beam irradiation (HLEBI) to the 2-layer assembly where the HLEBI penetrates through the PU and PTFE layers, respectively, prior to: (2) hot-press under 5MPa and 403K. Although the adhesion of the PU/PTFE sheets cannot be observed without the new double-step treatment, bonding forces were created as evidenced by the mean adhesive forces of peeling resistance ( o Fp). Based on the 3-parameter Weibull equation, the lowest o Fp value at Pp of zero (Fs) could be estimated. An increasing trend in Fs occurs by the double-step treatment applying HLEBI up to 0.43MGy reaching a maximum at 0.38Nm ¹1 , improving the safety level without radiation damage. When HLEBI cuts the chemical bonds and generates dangling bonds with nonbonding electrons in PU and PTFE, the created adhesion between the laminated sheets can be explained. Based on X-ray photoelectron spectrometer (XPS) surface analysis of the PU/PTFE laminated sheets after the peeling tests, fluorine (F) was detected on the PU peeled surface, indicating the strong chemical bonding generated by the double-step treatment. For these reasons, double-step treatment is a useful method for quick lamination of PU and PTFE with sterilization without the use of glue. [doi:10.2320/matertrans.MBW201216]

Creation of Adhesive Force between Laminated Sheets of Aluminum and Polyurethane by Homogeneous Low Energy Electron Beam Irradiation Prior to Hot-Press

2-layer aluminum/polyurethane (Al/PU) laminated sheets were prepared by a new adhesion method, a double-step treatment consisting of: (1) applying low dose 50:43MGy homogeneous low energy electron beam irradiation (HLEBI) to the 2-layer assembly where the HLEBI penetrates through the Al and PU layers, respectively, prior to: (2) hot-press under 5MPa and 403K. Although the adhesion of the Al/PU sheets cannot be observed without the new double-step treatment, bonding forces were created as evidenced by the mean adhesive forces of peeling resistance (Fp). Based on the 3-parameter Weibull equation, the lowest Fp value at peeling probability (Pp) of zero (Fs) could be estimated. An increasing trend in Fs occurs by the double-step treatment applying HLEBI up to 0.22MGy reaching a maximum at 34.0Nm11, improving the safety level without radiation damage. When HLEBI cuts the chemical bonds and generates dangling bonds with nonbonding electrons in Al and PU, the created adhesion between the laminated sheets can be explained. [doi:10.2320/matertrans.MAW201314]

Charpy Impact Value of Sandwich Structural (CFRP/ABS/CFRP) Composites Constructed with Carbon Fiber Reinforced Epoxy Polymer (CFRP) and Acrylonitrile Butadiene Styrene (ABS) Sheets Separately Irradiated by Electron Beam Prior to Lamination

Experimental results showed homogeneous 100keV-class low voltage electron beam irradiation (HLEBI) prior to lamination assembly (our new method) often improved the Charpy impact values (auc) of the sandwich structural CFRP/ABS/CFRP (carbon fiber reinforced epoxy polymer) and (acrylonitrile butadiene styrene) with low volume fraction of carbon fibers for cost reduction and safety. The auc values at each Pf of CFRP/ABS/CFRP laminated by both high-strength and light structural CFRP plies and ABS core separately irradiated from 0.04 to 0.30MGy-HLEBI before lamination were mostly higher than that without HLEBI. Although carefulness for aircraft parts would be necessary since higher doses of 0.30 and 0.43MGy HLEBI applied to the CFRP sheets and ABS core before lamination assembly reduced the lowest impact value at Pf = 0( as) calculated by 3-parameter Weibull equation, the low dose of 0.04MGy-HLEBI before lamination assembly apparently boosted the as almost 3 times, ³200%, over the untreated samples from 15 to 44kJm ¹2 . Moreover, applying the low dose of 0.04MGy-HLEBI before instead of after lamination apparently improved the as 76% from 25 to 44kJm ¹2 . Furthermore, applying the medium doses of 0.13MGy or 0.22MGy HLEBI before rather than after lamination appeared to improve the as remarkably from 0 to 40, and 0 to 42kJm ¹2 , respectively. The new method of applying HLEBI prior to lamination allows for more efficient beam contact to the inner core and its surface permitting deeper areas in thick laminated composites such as CFRP/ABS/CFRP to be treated generating dangling bonds, hence strengthening the bulk materials and the CFRP-ABS interface of the thick laminated CFRP/ABS/CFRP constructed with thin or thick surface sheet and thick core can be expected. [doi:10.2320/matertrans.MBW201209]

J045021 電子線照射処理による厚肉フッ素樹脂と異種高分子の接着([J045-02]知的材料・構造システム(2))

Fluororesin, which exhibits high wear resistance as well as high strength and fracture toughness, can be applied to artificial blood vessel. However, the fluororesin is difficult to glue. To laminate the fluororesin and different polymers of polydimethylsiloxane (PDMS) and polyethylene (PE), the new treatment of hot-press after homogeneous low voltage electron beam irradiation (HLEBI) was innovated without glue. The adhesive force (^oF_p) of peeling resistance of laminated sheets of fluororesin and different polymers of PDMS and PE was evaluated. In order to evaluate the influence of the hot- pressing after HLEBI on ^oF_p, electron spin resonance (ESR) signals related to dangling bonds were observed. When HLEBI cut the chemical bonds and generated dangling bonds with nonbonding electrons at terminated atoms in monomers of fluororesin, PDMS and PE, the nonbonding electrons induced not only the intermolecular attractive force but also chemical bonding. Therefore, the hot- pressing after HLEBI was a useful tool for quick lamination of fluororesin and different polymers of PDMS and PE without glue.

Reduced side effects by proton microchannel radiotherapy: study in a human skin model

The application of a microchannel proton irradiation was compared to homogeneous irradiation in a three-dimensional human skin model. The goal is to minimize the risk of normal tissue damage by microchannel irradiation, while preserving local tumor control through a homogeneous irradiation of the tumor that is achieved because of beam widening with increasing track length. 20MeV protons were administered to the skin models in 10- or 50-μm-wide irradiation channels on a quadratic raster with distances of 500μm between each channel (center to center) applying an average dose of 2Gy. For comparison, other samples were irradiated homogeneously at the same average dose. Normal tissue viability was significantly enhanced after microchannel proton irradiation compared to homogeneous irradiation. Levels of inflammatory parameters, such as Interleukin-6, TGF-Beta, and Pro-MMP1, were significantly lower in the supernatant of the human skin tissue after microchannel irradiation than after homogeneous irradiation. The genetic damage as determined by the measurement of micronuclei in keratinocytes also differed significantly. This difference was quantified via dose modification factors (DMF) describing the effect of each irradiation mode relative to homogeneous X-ray irradiation, so that the DMF of 1.21±0.20 after homogeneous proton irradiation was reduced to 0.23±0.11 and 0.40±0.12 after microchannel irradiation using 10- and 50-μm-wide channels, respectively. Our data indicate that proton microchannel irradiation maintains cell viability while significantly reducing inflammatory responses and genetic damage compared to homogeneous irradiation, and thus might improve protection of normal tissue after irradiation.

Anisotropic polarization, predicted as a result of the diffraction of blackbody radiation at a reflective phase grating with ideal conductivity

In the course of analyzing the axiomatic principles that form the basis of statistical physics, the validity of the postulate that all the isoenergetic microstates of a closed system are equally probable was checked. This article reports the results of numerically modelling the interaction of thermodynamically equilibrium blackbody radiation with a reflective phase diffraction grating that possesses ideal conductivity. Cases are found in which anisotropy of the polarization parameters is guaranteed to appear inside a closed volume of initially homogeneous blackbody radiation, resulting in a formal decrease of its Boltzmann entropy as a consequence of deviation from the microcanonical Gibbs distribution. This is apparently caused by the discontinuous character of the change of the phase trajectories of the photons during diffraction, which makes the physical system under consideration nonergodic.

Proteomic changes in the rat brain induced by homogenous irradiation and by the bystander effect resulting from high energy synchrotron X-ray microbeams

Purpose: To further evaluate the use of microbeam irradiation (MBI) as a potential means of non-invasive brain tumor treatment by investigating the induction of a bystander effect in non-irradiated tissue.Methods: Adult rats were irradiated with 35 or 350 Gy at the European Synchotron Research Facility (ESRF), using homogenous (broad beam) irradiation (HI) or a high energy microbeam delivered to the right brain hemisphere only. The proteome of the frontal lobes were then analyzed using two-dimensional electrophoresis (2-DE) and mass spectrometry.Results: HI resulted in proteomic responses indicative of tumourigenesis; increased albumin, aconitase and triosphosphate isomerase (TPI), and decreased dihydrolipoyldehydrogenase (DLD). The MBI bystander effect proteomic changes were indicative of reactive oxygen species mediated apoptosis; reduced TPI, prohibitin and tubulin and increased glial fibrillary acidic protein (GFAP). These potentially anti-tumourigenic apoptotic proteomic changes are also associated with neurodegeneration. However the bystander effect also increased heat shock protein (HSP) 71 turnover. HSP 71 is known to protect against all of the neurological disorders characterized by the bystander effect proteome changes.Conclusions: These results indicate that the collective interaction of these MBI-induced bystander effect proteins and their mediation by HSP 71, may confer a protective effect which now warrants additional experimental attention.

Improved performance of silicon‐nanoparticle film‐coated dye‐sensitized solar cells

AbstractSilicon (Si) nanoparticles with average size of 13 nm and orange–red luminescence under UV absorption were synthesized using electrochemical etching of silicon wafers. A film of Si nanoparticles with thickness of 0.75 µm to 2.6 µm was coated on the glass (TiO2 side) of a dye‐sensitized solar cell (DSSC). The cell exhibited nearly 9% enhancement in power conversion efficiency (η) at film thickness of ∼2.4 µm under solar irradiation of 100 mW/cm2 (AM 1.5) with improved fill factor and short‐circuit current density. This study revealed for the first time that the Si‐nanoparticle film converting UV into visible light and helping in homogeneous irradiation, can be utilized for improving the efficiency of the DSSCs. (© 2012 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

A Dynamic Electrical Scheme for the Optimal Reconfiguration of PV Modules under Non-Homogeneous Solar Irradiation

This paper presents a strategy for the maximization of the output power of photovoltaic (PV) systems under non homogeneous solar irradiation by means of automatic reconfiguration of the PV arrays layout. The innovation of the proposed approach is the employment of a simple Dynamic Electrical Scheme (DES), allowing a large number of possible modules interconnection, to be installed between the PV generator and the inverter. The models of the PV generator and of the DES have been realized and simulated with Simulink (Dynamic System Simulation for MATLAB). The attained experimental results appear to be quite interesting in terms of the attainable benefit in power and thus energy terms. The limited calculation times of the reconfiguration algorithm allows the application of the DES for the real time adaptation of the configuration to the changing weather conditions or other causes of non-uniform solar irradiation. Moreover, the results confirm that, in case of non uniform solar irradiation, this approach allows to attain considerably much better results than those attainable with a static configuration.

Active spot-scanning test with heavy ions at HIRFL-CSR

An active spot beam delivery system for heavy ion therapy has been developed based on the Cooling Storage Ring at HIRFL-CSR, where the pencil carbon-ion beams were scanned within a target volume transversely by a pair of orthogonal (horizontal and vertical) dipole magnets to paint the slices of the target volume and longitudinally by active energy variation of the synchrotron slice by slice. The unique techniques such as dose shaping via active energy variation and magnetic deflection constitute a promising three-dimensional conformal even intensity-modulated radiotherapy with heavy ions at HIRFL-CSR. In this paper, the verification of active energy variation and the calibration of steerable beam deflection are shown, as the basic functionality components of the active spot-scanning system. Additionally, based on the capability of creating homogeneous irradiation fields with steerable pencil beams, a radiobiological experiment like cell survival measurement has been performed aiming at comparison of the radiobiological effects under active and passive beam deliveries.

Microwave-assisted Stille and Hiyama cross-coupling reactions catalyzed by ortho-palladated complexes of homoveratrylamine

The activity of dimeric [Pd{C6H2(CH2CH2NH2)-(OMe)2-3,4}(μ-Br)]2 and monomeric [Pd{C6H2(CH2CH2NH2)-(OMe)2-3,4}Br(PPh3)] complexes as efficient, air, and moisture tolerant catalysts was investigated in Stille and Hiyama cross-coupling reactions of various aryl halides. Substituted biaryls were produced in excellent yields in short reaction times using these complexes. The monomeric complex had been demonstrated to be more active than the corresponding dimeric catalyst for the cross-coupling of some of aryl bromides and unreactive aryl chlorides. The combination of homogenous metal catalyst, microwave irradiation, and microwave-active polar solvents gave high yields of products in short reaction times.

SU-E-T-05: Comparing DNA Strand Break Yields for Photons under Different Irradiation Conditions with Geant4-DNA.

To validate and scrutinize published DNA strand break data with Geant4-DNA and a probabilistic model. To study the impact of source size, electronic equilibrium and secondary electron tracking cutoff on direct relative biological effectiveness (DRBE). Geant4 (v4.9.5) was used to simulate a cylindrical region of interest (ROI) with r = 15 nm and length = 1.05 mm, in a slab of liquid water of 1.06 g/cm3 density. The ROI was irradiated with mono-energetic photons, with a uniformly distributed volumetric isotropic source (0.28, 1.5 keV) or a plane beam (0.662, 1.25 MeV), of variable size. Electrons were tracked down to 50 or 10 eV, with G4-DNA processes and energy transfer greater than 10.79 eV was scored. Based on volume ratios, each scored event had a 0.0388 probability of happening on either DNA helix (break). Clusters of at least one break on each DNA helix within 3.4 nm were found using a DBSCAN algorithm and categorized as double strand breaks (DSB). All other events were categorized as single strand breaks (SSB). Geant4-DNA is able to reproduce strand break yields previously published. Homogeneous irradiation conditions should be present throughout the ROI for DRBE comparisons. SSB yields seem slightly dependent on the primary photon energy. DRBEs show a significant increasing trend for lower energy incident photons. A lower electron cutoff produces higher SSB yields, but decreases the SSB/DSB yields ratio. The probabilistic and geometrical DNA models can predict equivalent results. Using Geant4, we were able to reproduce previously published results on the direct strand break yields of photon and study the importance of irradiation conditions. We also show an ascending trend for DRBE with lower incident photon energies. A probabilistic model coupled with track structure analysis can be used to simulate strand break yields. NSERC, CIHR.

SU-E-T-111: Single Line Multi-Detector Scintillation Dosimetry: Demonstration of Feasibility.

Obtain feasibility data on the use of multiple scintillators on a single optical line for dose measurements. A CsI (Tl doped) crystal and a plastic (Rexon Inc, Rp-408) scintillator detectors, both transparent, were attached to the end of a fiberoptic line and connected to an Ocean Optics USB-2000 spectrometer. After baseline spectra, spectra with the two scintillators adjacent to each other and then separated by a 7.6 cm plexiglass spacer were obtained. Irradiations were performed using 6 MV X-ray beam from a Varian EX linear accelerator. Utilizing the baseline spectra the dose received by each scintillator were calculated from the measured spectral peaks of the linear scintillator assemblies. Linearity tests were performed by varying dose and the dose rate in a homogeneous radiation field covering both scintillators. Unequal doses were delivered to the scintillator by gradually closing the collimator from one direction, blocking one detector at a time. Doses to the scintillators were modulated by different amount of solid water placed over the two detectors, as well. Measured scintillation spectra agreed with the published spectra. The spectra did not change with depth in the phantom. The multi-scintillator system response was strictly linear between 1.67 and 40 MUs, (approx. 1.3 to 31 cGy) and dose rate independent between 100 to 600 MU/min. The profile curves obtained by closing the collimator agreed with qualitatively expected curves. Doses measured under different phantom thicknesses were in good agreement with ion chamber measurements on the same locations (+/- 3%). The linearity and dose rate independence allow absolute dose calibration for given beam energies and scintillator arrangement. Multi-probe scintillation dosimetry along a single optical fiber is possible in therapeutic irradiation conditions. This is feasible by using signals from multiple select scintillators with distinct spectroscopic responses arranged along an optical fiber.

Reduction of crystallization ability of sodium zinc phosphate glass under X-ray radiation

The effect of X-ray radiation on the crystallization ability of maximally homogenized sodium zinc phosphate glass with a minimal light scattering value of V v = 4 × 10−6 cm−1 has been investigated. The crystallization kinetics of the sodium zinc phosphate glass of the 33.9P2O5 · 56.6ZnO · 9.5Na2O (mol % from analysis) composition under the conditions of homogeneous nucleation and X-ray radiation have been studied. It has been demonstrated that the crystallization properties of phosphate glasses are more sensitive to the synthesis method than those of silicate glasses. It has been established that sodium zinc phosphate glass crystals represent the main crystalline phase precipitated in the glass of the above composition. The main parameters of nucleation have been determined in glass without preliminary radiation, including stationary nucleation rate I st, nonstationary nucleation time τ, and nucleation activation energy E τ. It have been found that the effect of the CuK α X-ray radiation leads to the slowing down or even cessation of the nucleation of crystals in glass (the result depends on the change in the radiation intensity along the sample depth) in the case when radiation takes place immediately during the nucleation thermal treatment of the sample in a high-temperature chamber of the X-ray device. The kinetics of sodium zinc phosphate crystallization in the samples upon their pretreatment by CuK α X-ray irradiation has been investigated. It has been shown that the rate of crystal nucleation in glasses exposed to X-ray radiation is lower than that in glasses without preliminary irradiation.

Integrative Modeling of Wireless RF Links for Train-to-Wayside Communication in Railway Tunnel

In railway tunnel environment, the reliability of a high-data-rate and real-time train-to-wayside communication should be maintained especially when high-speed train moves along the track. In China and Europe, the communication frequency around 900 MHz is widely used for railway applications. At this carrier frequency band, both of the solutions based on continuously laid leaky coaxial cable (LCX) and discretely installed base-station antennas (BSAs), are applied in tunnel radio coverage. Many available works have concentrated on the radio-wave propagation in tunnels by different kinds of prediction models. Most of them solve this problem as natural propagation in a relatively large hollow waveguide, by neglecting the transmitting/receiving (Tx/Rx) components. However, within such confined areas like railway tunnels especially loaded with train, the complex communication environment becomes an important factor that would affect the quality of the signal transmission. This paper will apply a full-wave numerical method to this case, for considering the BSA or LCX, train antennas and their interacted environments, such as the locomotive body, overhead line for power supply, locomotive pantograph, steel rails, ballastless track, tunnel walls, etc.. Involving finite-difference time-domain (FDTD) method and uni-axial anisotropic perfectly matched layer (UPML) technique, the entire wireless RF downlinks of BSA and LCX to tunnel space to train antenna are precisely modeled (so-called integrative modeling technique, IMT). When exciting the BSA and LCX separately, the field distributions of some cross-sections in a rectangular tunnel are presented. It can be found that the influence of the locomotive body and other tunnel environments is very significant. The field coverage on the locomotive roof plane where the train antennas mounted, seems more homogenous when the side-laying position of the BSA or LCX is much higher. Also, much smoother field coverage solution is achieved by choosing LCX for its characteristic of more homogenous electromagnetic wave radiation.

Modelling of a Traveling Bed WASTE Gasifier

This work deals with the modelling of a travelling bed waste gasifier. This gasifier is a part of a more general process devoted to the production of electricity from waste and refused derived fuel. In a first stage the load is dried and gasified in a travelling bed gasifier using air with an equivalence ratio of 0.3. This product gas contains light hydrocarbons as well as tars. It is converted into a syngas free from tars in a specific reformer (Turboplasma©) that uses plasma technology in order to raise the temperature of the incoming gas to a value compatible with thermal cracking of tars. The model of the travelling bed gasifier is based on the coupling between a software devoted to the description of the chemical and physical processes occurring within the travelling bed, and a CFD package (Fluent™) that allows for the description of the homogenous gas reaction and radiation occurring within the freeboard of the bed. The first software is a “home made” software based on the conservation equations of the solid, liquid and gas phases as well as of the energy. The balance equations are firstly written at the “phase scale”, and then, using a homogenisation technique (volume averaging) balance equations are derived at a representative volume scale. In this first work, this model is written using a one dimensional formalism along the axis of the travelling bed. Wood is used as a case study material with a pyrolysis mechanism that uses three parallel reactions leading to the formation of gas, tars and char. The gas and tars produced during the pyrolysis step can be converted within the bed itself but also over the freeboard of the bed. Hence, the free board of the bed is used as a boundary condition of the CFD domain, with known local mass flow-rate, composition and temperature. This study allows for a complete and precise description of the processes occurring within the gasifier under consideration.

Effect of different prosthetic materials on radiation dose distribution in an orbital defect: A clinical report

It is challenging to treat and irradiate empty cavities with external-beam radiation therapy (EBRT) because body contour irregularities can result in dose heterogeneities. The use of compensator materials to fill the empty cavities can provide a more homogeneous radiation dose distribution. The purposes of this clinical report are to describe the use of 3 different materials (elastomeric material, water-filled balloon, and acrylic resin) in an orbital defect and compare the dosimetric parameters and photon-electron dose distribution during EBRT.