Energy Transfer Values Research Articles

Numerical simulation of flow around an orbiting cylinder at different ellipticity values

This paper deals with the numerical simulation of low Reynolds number flow (Re=120–180) past a circular cylinder in orbital motion. The Navier–Stokes equations, pressure Poisson equations and continuity are written in primitive variables in a noninertial system fixed to the orbiting cylinder and solved by the finite difference method. Ellipticity values between 0 and 1.2 (from pure in-line oscillation through a full circle and beyond) were investigated. Sudden changes in state (jumps) are found when time-mean or root-mean-square values of force coefficients or energy transfer are plotted against ellipticity. Pre- and post-jump analysis was carried out by investigating limit cycles, time-histories, phase angles and flow patterns. These investigations revealed that ellipticity can have a large effect on the energy transfer between the incompressible fluid and a circular cylinder forced to follow an orbital path, and that small changes in the amplitude of transverse motion can have a dramatic effect. The phase angle was altered by about 180° at the jumps. Also investigated were the direction of orbit, which affects the state curves belonging to the time-mean values of lift only, and the effect of initial conditions, which alters the location of jumps without changing the state curves.

Heavy-Ion-Induced Sucrose and L-α-Alanine Radicals Investigated by EPR

We investigated the details of sucrose and L-α-alanine radicals produced by heavy-ion irradiation with various linear energy transfer (LET) values. The impact of the heavy ions on samples produced stable free radicals, which were analyzed by electron paramagnetic resonance (EPR). The spectral patterns obtained were similar among those for the irradiation of carbon (C), neon (Ne), silicon (Si), and argon (Ar) ions. The radical production of irradiated sucrose and alanine samples showed a linear relation with the absorbed dose. The total spin concentration obtained by heavy-ion irradiation decreases as logarithmic function of the LET. Quantitative EPR analysis showed that the production of sucrose and alanine radicals depended on both the ion species and the LET values under the same dose. Moreover, the radical-production cross sections for sucrose and alanine irradiated with C ions (290 MeV/u) were about 1.3 · 10−8 and about 3.0 · 10−9 µm2, respectively. The results of the cross section suggest that each molecule becomes a stable radical with the interaction of several particles.

Radiobiologic Parameters and Local Effect Model Predictions for Head-and-Neck Squamous Cell Carcinomas Exposed to High Linear Energy Transfer Ions

To establish the radiobiologic parameters of head-and-neck squamous cell carcinomas (HNSCC) in response to ion irradiation with various linear energy transfer (LET) values and to evaluate the relevance of the local effect model (LEM) in HNSCC. Cell survival curves were established in radiosensitive SCC61 and radioresistant SQ20B cell lines irradiated with [33.6 and 184 keV/n] carbon, [302 keV/n] argon, and X-rays. The results of ion experiments were confronted to LEM predictions. The relative biologic efficiency ranged from 1.5 to 4.2 for SCC61 and 2.1 to 2.8 for SQ20B cells. Fixing an arbitrary D(0) parameter, which characterized survival to X-ray at high doses (>10 Gy), gave unsatisfying LEM predictions for both cell lines. For D(0) = 10 Gy, the error on survival fraction at 2 Gy amounted to a factor of 10 for [184 keV/n] carbon in SCC61 cells. We showed that the slope (s(max)) of the survival curve at high doses was much more reliable than D(0). Fitting s(max) to 2.5 Gy(-1) gave better predictions for both cell lines. Nevertheless, LEM could not predict the responses to fast and slow ions with the same accuracy. The LEM could predict the main trends of these experimental data with correct orders of magnitude while s(max) was optimized. Thus the efficiency of carbon ions cannot be simply extracted from the clinical response of a patient to X-rays. LEM should help to optimize planning for hadrontherapy if a set of experimental data is available for high-LET radiations in various types of tumors.

Pressure dependent reactions for atmospheric and combustion models

In order to characterize reactions as functions of temperature, pressure (molecular density) and the nature of the species that constitute that molecular density, master equation solutions are required. In this tutorial review, the application of the Multiwell suite of codes to some reactions of interest in atmospheric and combustion chemistry is discussed, with attention given to the details of the molecular and energy transfer values. Uncertainties in data and in structural and energetic molecular parameters combine to assure the need for optimization and collaborative processing of the entire data base when modeling practical systems.

Generation of excess charge carriers in molecularly doped polymers by electron-beam irradiation

The processes of generation and transport of excess charge carriers in molecularly doped polycarbonate and polystyrene were experimentally studied at room temperature. The polymers were ionized by 7-and 50-keV electrons. The radiation-chemical yield of free ions was determined by means of the universal method based on the combination of the time-of-flight technique in two carrier generation modes (surface and bulk generation) with the measurement of nonsteady-state conductivity. It was shown that the radiation-chemical yield of free ions under irradiation by 7-keV electrons is almost the same as that in the case of 50-keV electrons, despite the substantially different values of the linear energy transfer for these electrons.

The radiosensitivity of total and quiescent cell populations in solid tumors to 290 MeV/u carbon ion beam irradiation in vivo

Purpose. To clarify the radiosensitivity of intratumor total and quiescent (Q) cells in vivo to accelerated carbon ion beams compared with γ-ray irradiation. Materials and methods. SCC VII tumor-bearing mice received a continuous administration of 5-bromo-2′-deoxyuridine (BrdU) to label all intratumor proliferating (P) cells. Then they received 290 MeV/u carbon ions or γ-rays. Immediately or 12 hours after the irradiation, the radiosensitivity of Q cells was assessed in terms of the micronucleus frequency using immunofluorescence staining for BrdU. That of the total (=P+Q) tumor cells was determined from the BrdU non-treated tumors based on the micronucleus frequency and clonogenic cell survival. Results. The apparent difference in radiosensitivity between total and Q cell populations under γ-ray irradiation was markedly reduced with carbon ion beam, especially with a higher linear energy transfer (LET) value. Clearer repair in Q cells than total cells through delayed assay under γ-ray irradiation was efficiently inhibited with carbon ion beams, especially with a higher LET. Conclusion. In terms of tumor cell-killing effect as a whole, including intratumor Q cells, carbon ion beams, especially with higher LET values, were very useful for suppressing the dependency on the heterogeneity within solid tumors as well as depositing radiation dose precisely.

Swift heavy ion induced single event upsets in high density UV-EPROM’s

A few high density UV-EPROM’s (32Kb×8) were irradiated with 5.41MeV energy α-particles with fluences from 104 to 108alphas/cm2 and 100MeV nickel, iodine and silver ions for low fluences between 5×107 and 108ions/cm2. The energy and ion species was selected on the basis of predicted threshold values of linear energy transfer (LET) in silicon. The program which was stored in the memory found to be changed from 0 to 1 and 1 to 0 state, respectively. On the basis of changed states, the cross-sections (σ) were calculated to investigate the single event effects/upsets. No upset was observed in case of α-particle since it has very low LET, but the SEU cross-section found to be more in case of Iodine i.e. 2.29×10−3 cm2 than that of nickel, 2.12×10−3cm2 and silver, 2.26×10−3. This mainly attributes that LET for iodine is more as compared to silver and nickel ions, which deposits large amount of energy near the sensitive node of memory cell in the form of electron-hole pairs required to change the state. These measured SEU cross-section were also compared with theoretically predicted values along with the Weibull distribution fit to the ion induced experimental SEU data. The theoretical predicted SEU cross-section 3.27×10−3cm2 found to be in good agreement with the measured SEU cross-section.

Radiobiologic Significance of Response of Intratumor Quiescent Cells In Vivo to Accelerated Carbon Ion Beams Compared With γ-Rays and Reactor Neutron Beams

To clarify the radiosensitivity of intratumor quiescent cells in vivo to accelerated carbon ion beams and reactor neutron beams. Squamous cell carcinoma VII tumor-bearing mice were continuously given 5-bromo-2'-deoxyuridine to label all intratumor proliferating cells. Next, they received accelerated carbon ion or gamma-ray high-dose-rate (HDR) or reduced-dose-rate (RDR) irradiation. Other tumor-bearing mice received reactor thermal or epithermal neutrons with RDR irradiation. Immediately after HDR and RDR irradiation or 12 h after HDR irradiation, the response of quiescent cells was assessed in terms of the micronucleus frequency using immunofluorescence staining for 5-bromo-2'-deoxyuridine. The response of the total (proliferating plus quiescent) tumor cells was determined from the 5-bromo-2'-deoxyuridine nontreated tumors. The difference in radiosensitivity between the total and quiescent cell populations after gamma-ray irradiation was markedly reduced with reactor neutron beams or accelerated carbon ion beams, especially with a greater linear energy transfer (LET) value. Clearer repair in quiescent cells than in total cells through delayed assay or a decrease in the dose rate with gamma-ray irradiation was efficiently inhibited with carbon ion beams, especially with a greater LET. With RDR irradiation, the radiosensitivity to accelerated carbon ion beams with a greater LET was almost similar to that to reactor thermal and epithermal neutron beams. In terms of tumor cell-killing effect as a whole, including quiescent cells, accelerated carbon ion beams, especially with greater LET values, are very useful for suppressing the dependency on the heterogeneity within solid tumors, as well as depositing the radiation dose precisely.

Carbon dioxide emissions in the aspect of applied engine fuels

The article addresses some questions concerning the exhaust gas carbon dioxide emissions as a result of applying different kinds of engine fuels. The current exhaust emission regulations are provided in the article together with the new standards that have been proposed. In addition, the paper discusses some present methods applied to decrease carbon dioxide emissions from combustion engines, including the use of new fuels. The following part of the article provides a calculation procedure of carbon dioxide emissions and proposes a new comparative method of evaluating carbon dioxide emissions with respect to different fuels. The criterion for the comparison is the value of energy transfer as an air-fuel mixture to the engine. This coefficient of carbon dioxide emissions allows a comparison between emissions in the case of various fuels with reference to gasoline and to draw some conclusions.

Photophysical properties, excitation energy transfer and laser activity of 3-(4′-dimethylaminophenyl)-1-(2-pyridinyl) prop-2-en-1-one (DMAPP): A new potential laser dye

The photophysical properties such as singlet absorption, molar absorptivity, fluorescence spectra, fluorescence quantum yield ( ϕ f) and transition dipole moment ( μ 12) of 3-(4′-dimethylaminophenyl)-1-(2-pyridinyl) prop-2-en-1-one (DMAPP) were measured in different media. DMAPP dye exhibits a large red shift in both absorption and emission spectra as solvent polarity increases, indicating a large change in dipole moment of molecule upon excitation. Also, the fluorescence quantum yield is solvent dependent. A crystalline solid of DMAPP gives excimer like emission at 585 nm. Dye solution ca 1 × 10 −3 mol dm −3 in CHCl 3 gives a good laser emission in the range 440–600 nm with emission maximum at 550 nm upon pumping by nitrogen laser ( λ ex = 337.1 nm). The excitation energy transfer from 7-dimethylamino-4-methyl coumarine (DMC) to DMAPP has also been studied in CHCl 3 and the value of energy transfer and critical transfer distance indicate a Főrster-type mechanism. The photochemical quantum yields ( ϕ c) of DMAPP in chloromethane solvents are also determined.

Characterisation of a Δ E– E particle telescope using the ANSTO heavy ion microprobe

Semiconductor planar processing technology has spurned the development of novel radiation detectors with applications in space, high energy physics, medical diagnostics, radiation protection and cancer therapy. The ANSTO heavy ion microprobe, which allows a wide range of ions to be focused into spot sizes of a few micrometers in diameter, has proven to be an essential tool for characterising these detectors using the Ion Beam Induced Charge (IBIC) imaging technique. The use of different ions and the wide range of available energies on the heavy ion microprobe, allows the testing of these devices with ionising particles associated with different values of linear energy transfer (LET). Quadruple coincidence measurements have been used to map the charge collection characteristics of a monolithic Δ E– E telescope. This was done through simultaneous measurement of the spatial coordinates of the microbeam relative to the sample and the response of both detector elements. The resulting charge collection maps were used to better understand the functionality of the device as well as to ascertain ways in which future device designs could be modified to improve performance.

Simulation of light ion induced DNA damage patterns

The biophysical simulation code PARTRAC was extended by a module to handle ions heavier than alpha particles. Cross sections for ion-electron interactions were taken from He(++) ions of the same velocity and scaled by Z(eff(2))/4. Calculated linear energy transfer values, radial dose distributions and secondary electron spectra were found in agreement with experimental results. DNA damage due to irradiation of human fibroblast cells by several light ions from H to S was calculated for various energies complemented by 220 kV(p) X rays as reference radiation. With increasing linear energy transfer, the calculated total yield of double-strand breaks per dose showed saturation behaviour at about twice the value for reference radiation. When data analysis methods for experimental double-strand break yield determination were applied to the simulated DNA damage patterns, the two data sets were found in accord. The calculated patterns of DNA damage clusters were analysed on local and regional scale finding regional clusters in closer correlation to experimental cell inactivation data.

Mapping the GRIF-1 Binding Domain of the Kinesin, KIF5C, Substantiates a Role for GRIF-1 as an Adaptor Protein in the Anterograde Trafficking of Cargoes

Gamma-aminobutyric acid, type A (GABAA) receptor interacting factor-1 (GRIF-1) and N-acetylglucosamine transferase interacting protein (OIP) 106 are both members of a newly identified coiled-coil family of proteins. They are kinesin-associated proteins proposed to function as adaptors in the anterograde trafficking of organelles to synapses. Here we have studied in more detail the interaction between the prototypic kinesin heavy chain, KIF5C, kinesin light chain, and GRIF-1. The GRIF-1 binding site of KIF5C was mapped using truncation constructs in yeast two-hybrid interaction assays, co-immunoprecipitations, and co-localization studies following expression in mammalian cells. Using these approaches, it was shown that GRIF-1 and the KIF5C binding domain of GRIF-1, GRIF-1-(124-283), associated with the KIF5C non-motor domain. Refined studies using yeast two-hybrid interactions and co-immunoprecipitations showed that GRIF-1 and GRIF-1-(124-283) associated with the cargo binding region within the KIF5C non-motor domain. Substantiation that the GRIF-1-KIF5C interaction was direct was shown by fluorescence resonance energy transfer analyses using fluorescently tagged GRIF-1 and KIF5C constructs. A significant fluorescence resonance energy transfer value was found between the C-terminal EYFP-tagged KIF5C and ECFP-GRIF-1, the C-terminal EYFP-tagged KIF5C non-motor domain and ECFP-GRIF-1, but not between the N-terminal EYFP-tagged KIF5C nor the EYFP-KIF5C motor domain and ECFP-GRIF-1, thus confirming direct association between the two proteins at the KIF5C C-terminal and GRIF-1 N-terminal regions. Co-immunoprecipitation and confocal imaging strategies further showed that GRIF-1 can bind to the tetrameric kinesin light-chain/kinesin heavy-chain complex. These findings support a role for GRIF-1 as a kinesin adaptor molecule requisite for the anterograde delivery of defined cargoes such as mitochondria and/or vesicles incorporating beta2 subunit-containing GABAA receptors, in the brain.

The efficiency of various thermoluminescence dosemeter types to heavy ions

Dose verification in heavy-ion beams using passive dosemeter systems, e.g. thermoluminescence dosemeters (TLDs), is crucial due to the changing efficiency of the dosemeters for different ion species and linear energy transfer (LET) values. This behaviour leads to a falsification of absorbed dose that can be significant for many applications, e.g. in space or radiotherapeutic dosimetry. TLDs can only be established as a 'reference' system in heavy-ion beams or other radiation fields if the efficiency functions for all contributing ion species and LET values are provided. In the framework of a research project of the Atominstitute of the Austrian Universities irradiations with various ions were performed in the years 2001-2003 at the Heavy Ion Medical Accelerator (HIMAC) of the National Institute for Radiological Sciences (NIRS) in Chiba, Japan. Efficiency values were recorded in dependence on ion species and LET in a range from 2 to 400 keV microm(-1). The efficiencies of five different commercially available TLD materials namely TLD 600, TLD 700, TLD 700H, TLD 300 and TLD 200 were investigated.

LET and dose dependence of TLD-100 glow curve after exposure to intermediate-energy ions

We present results from measurements performed with low fluences (10(5)-10(6) cm(-2)) of 15, 25 and 40 MeV u(-1) carbon, 25 MeV u(-1) oxygen and 40 MeV u(-1) neon ions incident on TLD-100 chips. Dosemeters were arranged individually or in stacks in front of the beam, allowing the study of various linear energy transfer (LET) values simultaneously. The thermoluminescence (TL) total signal is observed to be a linear function of deposited energy. To assess the contribution to the glow curve from the high-temperature peaks, two methods were studied: ratios of peak heights (peak 7 with respect to peak 5), and ratios of areas of the deconvoluted high-temperature peaks with respect to peak 5. The ratios were evaluated as a function of dose, showing in both methods a dependence on LET and ion identity. Some of the studied ions show these ratios to be independent of dose, up to 500 mGy, while for other ions, departures from linearity up to 4.5% +/- 2.5% per 100 mGy are observed at 500 mGy. These results show that, in general, the incident radiation LET is not a parameter that can be deduced from the glow curve.

Detailed analysis of the cell-inactivation mechanism by accelerated protons and light ions

A detailed study of the biological effects of diverse quality radiations, addressing their biophysical interpretation, is presented. Published survival data for V79 cells irradiated by monoenergetic protons, helium-3, carbon and oxygen ions and for CHO cells irradiated by carbon ions have been analysed using the probabilistic two-stage model of cell inactivation. Three different classes of DNA damage formed by traversing particles have been distinguished, namely severe single-track lesions which might lead to cell inactivation directly, less severe lesions where cell inactivation is caused by their combinations and lesions of negligible severity that can be repaired easily. Probabilities of single ions forming these lesions have been assessed in dependence on their linear energy transfer (LET) values. Damage induction probabilities increase with atomic number and LET. While combined lesions play a crucial role at lower LET values, single-track damage dominates in high-LET regions. The yields of single-track lethal lesions for protons have been compared with Monte Carlo estimates of complex DNA lesions, indicating that lethal events correlate well with complex DNA double-strand breaks. The decrease in the single-track damage probability for protons of LET above approximately 30 keV µm−1, suggested by limited experimental evidence, is discussed, together with the consequent differences in the mechanisms of biological effects between protons and heavier ions. Applications of the results in hadrontherapy treatment planning are outlined.

Melting of Au and Al in nanometer Fe/Au and Fe/Al multilayers under swift heavy ions: A thermal spike study

Knowing that Fe is sensitive to swift heavy ion irradiations whereas Au and Al are not, the behavior of nanometric metallic multilayer systems, like [Fe(3nm)/Au(x)]y and [Fe(3nm)/Al(x)]y with x ranging between 1 and 10nm, were studied within the inelastic thermal spike model. In addition to the usual cylindrical geometry of energy dissipation perpendicular to the ion projectile direction, the heat transport along the ion path was implemented in the electronic and atomic sub-systems. The simulations were performed using three different values of linear energy transfer corresponding to 3MeV/u of 208Pb, 132Xe and 84Kr ions. For the Fe/Au system, evidence of appearance of a molten phase was found in the entire Au layer, provided the Au thickness is less than 7nm and 3nm for Pb and Xe ions, respectively. For the Fe/Al(x) system irradiated with Pb ions, the Al layers with a thickness less than 4nm melt along the entire ion track. Surprisingly, the Fe layer does not melt if the Al thickness is larger than 2nm, although the deposited energy surpasses the electronic stopping power threshold of track formation in Fe. For Kr ions melting does not occur in any of the multilayer systems.

Linear energy transfer dependence of the effects of carbon ion beams on adventitious shoot regeneration from in vitro leaf explants of Saintpaulia ionahta

Purpose: To determine the effects of carbon ion beams with five different linear energy transfer (LET) values on adventitious shoots from in vitro leaf explants of Saintpaulia ionahta Mauve cultivar with regard to tissue increase, shoots differentiation and morphology changes in the shoots.Materials and methods: In vitro leaf explant samples were irradiated with carbon ion beams with LET values in the range of 31∼151 keV/µm or 8 MeV of X-rays (LET = 0.2 keV/µm) at different doses. Fresh weight increase, surviving fraction and percentage of the explants with regenerated malformed shoots in all the irradiated leaf explants were statistically analysed.Results: The fresh weight increase (FWI) and surviving fraction (SF) decreased dramatically with increasing LET at the same doses. In addition, malformed shoots, including curliness, carnification, nicks and chlorophyll deficiency, occurred in both carbon ion beam and X-ray irradiations. The induction frequency with the former, however, was far more than that with the X-rays.Conclusions: This work demonstrated the LET dependence of the relative biological effectiveness (RBE) of tissue culture of Saintpaulia ionahta according to 50% FWI and 50% SF. After irradiating leaf explants with 5 Gy of a 221 MeV carbon ion beam having a LET value of 96 keV/µm throughout the sample, a chlorophyll-deficient (CD) mutant, which could transmit the character of chlorophyll deficiency to its progeny through three continuous tissue culture cycles, and plantlets with other malformations were obtained.

Computer program for analyzing donor photobleaching FRET image series

The photobleaching fluorescence resonance energy transfer (pbFRET) technique is a spectroscopic method to measure proximity relations between fluorescently labeled macromolecules using digital imaging microscopy. To calculate the energy transfer values one has to determine the bleaching time constants in pixel-by-pixel fashion from the image series recorded on the donor-only and donor and acceptor double-labeled samples. Because of the large number of pixels and the time-consuming calculations, this procedure should be assisted by powerful image data processing software. There is no commercially available software that is able to fulfill these requirements. New evaluation software was developed to analyze pbFRET data for Windows platform in National Instrument LabVIEW 6.1. This development environment contains a mathematical virtual instrument package, in which the Levenberg-Marquardt routine is also included. As a reference experiment, FRET efficiency between the two chains (beta2-microglobulin and heavy chain) of major histocompatibility complex (MHC) class I glycoproteins and FRET between MHC I and MHC II molecules were determined in the plasma membrane of JY, human B lymphoma cells. The bleaching time constants calculated on pixel-by-pixel basis can be displayed as a color-coded map or as a histogram from raw image format. In this report we introduce a new version of pbFRET analysis and data processing software that is able to generate a full analysis pattern of donor photobleaching image series under various conditions. .

Dose distribution of carbon ions in air assessed using imaging plates and ionization chamber

A system to expose biological specimens to medium-energy (2.6–6.0 MeV/u) irradiation has been developed at the NIRS-HIMAC. In order to determine the beam energy or LET at the irradiation position in air, the dose distribution for 6.0 MeV/u carbon beam has been obtained using a secondary electron monitor and a flat-type ionization chamber by using air as the energy absorber. Imaging plates were applied to assess the beam profile distribution. The intensity of photo-stimulated luminescence (PSL) was found to be almost proportional to the energy deposited within the sensitive layer of the imaging plate. It has been confirmed that a uniform irradiation field can be produced (about ± 5 % within 20 mm in diameter) at low-intensity exposure from 10 1 to 10 4 ions / cm 2 / s . Long-term beam stability in the low-intensity condition has also been demonstrated. As a consequence, the methodology for uniform, stable and low-intensity beam exposure has been established, and the continuously variable linear energy transfer (LET) values have also been obtained by changing the distance from the endcap of beamport, for biological studies.