Diode-pumped quasi-three-level Nd:GdV O4–Nd:YAG sum-frequency laser at 464 nm

International Nuclear Information System (INIS)

Lu, Jie

2014-01-01

We report a laser architecture to obtain continuous-wave (cw) blue radiation at 464 nm. A 808 nm diode pumped a Nd:GdV O 4 crystal emitting at 912 nm. A part of the pump power was then absorbed by the Nd:GdV O 4 crystal. The remainder was used to pump a Nd:YAG crystal emitting at 946 nm. Intracavity sum-frequency mixing at 912 and 946 nm was then realized in a LiB 3 O 5 (LBO) crystal to produce blue radiation. We obtained a cw output power of 1.52 W at 464 nm with a pump laser diode emitting 18.4 W at 808 nm. (letter)

New silicon photodiodes for detection of the 1064nm wavelength radiation

Science.gov (United States)

Wegrzecki, Maciej; Piotrowski, Tadeusz; Puzewicz, Zbigniew; Bar, Jan; Czarnota, Ryszard; Dobrowolski, Rafal; Klimov, Andrii; Kulawik, Jan; Kłos, Helena; Marchewka, Michał; Nieprzecki, Marek; Panas, Andrzej; Seredyński, Bartłomiej; Sierakowski, Andrzej; Słysz, Wojciech; Synkiewicz, Beata; Szmigiel, Dariusz; Zaborowski, Michał

2016-12-01

In this paper a concept of a new bulk structure of p+-υ-n+ silicon photodiodes optimized for the detection of fast-changing radiation at the 1064 nm wavelength is presented. The design and technology for two types of quadrant photodiodes, the 8-segment photodiode and the 32-element linear photodiode array that were developed according to the concept are described. Electric and photoelectric parameters of the photodiodes mentioned above are presented.

Low-level radiation

International Nuclear Information System (INIS)

Myers, D.K.

1982-05-01

It is known that the normal incidence of cancer in human populations is increased by exposure to moderately high doses of ionizing radiation. At background radiation levels or at radiation levels which are 100 times greater, the potential health risks are considered to be directly proportional to the total accumulated dose of radiation. Some of the uncertainties associated with this assumption and with the accepted risk estimates have been critically reviewed in this document. The general scientific consensus at present suggests that the accepted risk estimates may exaggerate the actual risk of low levels of sparsely ionizing radiations (beta-, gamma- or X-rays) somewhat but are unlikely to overestimate the actual risks of densely ionizing radiations (fast neutrons, alpha-particles). At the maximum permissible levels of exposure for radiation workers in nuclear power stations, the potential health hazards in terms of life expectancy would be comparable to those encountered in transportation and public utilities or in the construction industry. At the average radiation exposures received by these workers in practice, the potential health hazards are similar to those associated with safe categories of industries. Uranium mining remains a relativly hazardous occupation. In terms of absolute numbers, the genetic hazards, which are less well established, are thought to be smaller than the carcinogenic hazards of radiation when only the first generation is considered but to be of the same order of magnitude as the carcinogenic hazards when the total number of induced genetic disorders is summed over all generations

Preparation and Characterization of Bragg Fibers for Delivery of Laser Radiation at 1064 nm

Directory of Open Access Journals (Sweden)

V. Matejec

2013-04-01

Full Text Available Bragg fibers offer new performance for transmission of high laser energies over long distances. In this paper theoretical modeling, preparation and characterization of Bragg fibers for delivery laser radiation at 1064 nm are presented. Investigated Bragg fibers consist of the fiber core with a refractive index equal to that of silica which is surrounded by three pairs of circular layers. Each pair is composed of one layer with a high and one layer with a low refractive index and characterized by a refractive-index difference around 0.03. Propagation constants and radiation losses of the fundamental mode in such a structure were calculated on the basis of waveguide optics. Preforms of the Bragg fibers were prepared by the MCVD method using germanium dioxide, phosphorous pentoxide and fluorine as silica dopants. The fibers with a diameter of 170 m were drawn from the preforms. Refractive-index profiles, angular distributions of the output power and optical losses of the prepared fibers were measured. Results of testing the fibers for delivery radiation of a pulse Nd:YAG laser at 1064 nm are also shown.

Generation of continuous-wave single-frequency 1.5 W 378 nm radiation by frequency doubling of a Ti:sapphire laser.

Science.gov (United States)

Cha, Yong-Ho; Ko, Kwang-Hoon; Lim, Gwon; Han, Jae-Min; Park, Hyun-Min; Kim, Taek-Soo; Jeong, Do-Young

2010-03-20

We have generated continuous-wave single-frequency 1.5 W 378 nm radiation by frequency doubling a high-power Ti:sapphire laser in an external enhancement cavity. An LBO crystal that is Brewster-cut and antireflection coated on both ends is used for a long-term stable frequency doubling. By optimizing the input coupler's reflectivity, we could generate 1.5 W 378 nm radiation from a 5 W 756 nm Ti:sapphire laser. According to our knowledge, this is the highest CW frequency-doubled power of a Ti:sapphire laser.

Mutagenic action of non-ionizing radiations: its implication in radiation protection

International Nuclear Information System (INIS)

Madhvanath, U.; Subrahmanyam, P.; Sankaranarayanan, N.; Singh, D.R.

1977-01-01

Mutagenic effects of non-ionizing radiations except in the ultraviolet and near ultraviolet region are just not known. Results of the investigation carried out using a sensitive diploid yeast system, are presented. The arginine requiring mutant yeast strain BZ34 reverts to prototrophy following exposure to ionizing radiation. Reversion frequencies were determined following exposure to UV (254 nm), near ultraviolet (313, 353 nm) visible region (480 nm), neodymium laser (1.01 μm) and microwave (2450 MHz) radiations. An Aminco - Bowman Spectrophotofluorimeter was used to obtain wavelengths from UV to visible region. Yeast suspensions (concentration of 10 7 cells/ml) were irradiated to doses ranging from 10 7 to 10 9 erg/cm 3 as determined with potassium ferri-oxalate system. Exposure to laser pulses and microwave radiation ranged up to 45 J/cm 2 and 60 mW-h/cm 2 respectively. Results showed that the reversion induction efficiency decreased by six orders of magnitude from ionizing radiations to ultraviolet for the same absorbed dose and this efficiency has further decreased by a factor of fifteen when the wavelength is increased from 254 nm to 313 nm. Although killing could be effected with laser beams (45 J/cm 2 for 50% survival) no increase in the reversion was observed than the background level. It is concluded that radiation of wavelengths higher than 450 nm up to 12 cm studied is not mutagenic and with sufficient intensities of these radiations only killing of cells is possible due to thermal effects. This finding is compared with other known functional and morphological effects at cellular level due to low-level exposures of non-ionizing radiations

New apparatus with high radiation energy between 320 to 460 nm: physical description and dermatological applications

International Nuclear Information System (INIS)

Mutzhas, M.F.; Holzle, E.; Hofmann, C.; Plewig, G.

1981-01-01

A new apparatus (UVASUN 5000) is presented with high radiation energy between 320 to 460 nm. The radiator is a specially developed source for high uv-A intensity, housing a quartz bulb with a mixture of argon, mercury and metal-halides. The uv-A energy in the range of 320 to 400 nm is about 84% of the total radiation energy. Effects of very high doses of uv-A on human skin were studied. Following single uv-A applications the minimal tanning dose uv-A (MTD) and the immediate pigment darkening (IPD) dose of uv-A were established. Repeated exposure to this uv-A delivering system yields long lasting dark brown skin pigmentation without any clinical or histological signs of sunburn (uv-B) damage, epidermal hyperplasia or thickening of the stratum corneum. Minimal therapeutic results were seen in the phototherapy of vitiligo and inflammatory acne

New apparatus with high radiation energy between 320-460 nm: physical description and dermatological applications

International Nuclear Information System (INIS)

Mutzhas, M.F.; Holzle, E.; Hofmann, C.; Plewig, G.

1981-01-01

A new apparatus (UVASUN 5000) is presented with high-radiation energy between 320 to 460 nm. The measureable energy below 320 nm was shown to be many orders of magnitude too low to produce erythema. The radiator is a specially developed source for high uv-A intensity, housing a quartz bulb with a mixture of argon, mercury and metal-halides. At a skin-target distance of 0.2 m the size of the irradiated area is 0.35 x 0.35 m, and the measured mean uv-A intensity is about 1400 W. m-2 (140 mW . cm-2). The uv-A energy in the range of 320 to 400 nm is about 84% of the total radiation energy. Effects of very high doses of uv-A on human skin were studied. Following single uv-a applications the minimal tanning dose uv-A (MTD) and the immediate pigment darkening (IPD) dose of uv-A were established. The calculated IPD threshold time was 1.8 min at 0.2 m. Repeated exposure to this uv-A delivering system yields long lasting dark brown skin pigmentation without any clinical or histological signs of sunburn (uv-B) damage, epidermal hyperplasia or thickening of the stratum corneum. The instrument was also successfully used for photo-patch testing and reproduction of skin lesions of polymorphous light eruption. Minimal therapeutic results were seen in the phototherapy of vitiligo and inflammatory acne

Mutagenicity of monoadducts and cross-links induced in Aspergillus nidulans by 8-methoxypsoralen plus 365 nm radiation

International Nuclear Information System (INIS)

Scott, B.R.; Maley, M.A.

1981-01-01

8-Methoxypsoralen plus 365 nm radiation induces mutation at the methionine supressor loci of Aspergillus inhibitor-deficient conidia at low doses of near-UV radiation with one-hit kinetics and at higher near-UV radiation doses with two-hit kinetics. These results and others suggest that both monoadducts and cross-links, formed by 8-methoxypsoralen and DNA upon exposure to UV radiation, are capable of inducing mutation. Evidence is also presented that induced furocoumarin cross-links are responsible for the inactivation of the Aspergillus conidium. (author)

Comparative analysis of the effect of the GaAlAs laser irradiation in 780 nm and 660 nm in the hypersensitive dentin; Analise comparativa do efeito da irradiacao do laser de GaAlAs em 780 nm e 660 nm na hipersensibilidade dentinaria

Energy Technology Data Exchange (ETDEWEB)

Yuan, Sun Chien

2003-07-01

This study was to evaluate and compare the effects of the low intensity in laser radiation among GaAlAs 780 nm and GaAlAs 660 nm. The main proposal is to verify if there is any difference of the effects or results in low intensity laser application treatment of hypersensitive dentin, keeping the same parameters, only differing in wavelength. The samples were distributed in two groups. Group A 90 cases, treated with GaAlAs 780 nm and group B irradiated with GaAlAs 660 nm with a total of 76 cases analyzed. The results of application with GaAlAs 660 nm and GaAlAs 780 nm do not differ statistically. Which means using any one of the irradiation gives the same results. However can be noted that the response of reduction of hypersensitivity is faster with the radiation of GaAlAs 780 nm, but the results after three applications is the same for both types of radiation. (author)

Multiphoton ionization and fragmentation study of acetone using 308 nm laser radiation

Science.gov (United States)

Liu Houxiang, Li Shutao, Han Jingcheng, Zhu Rong, Guan Yifu, Wu Cunkai

1988-10-01

Multiphoton ionization and fragmentation (MPI-F) of acetone molecules using 308 nm laser radiation was studied by using a molecular beam and quadrupole mass spectrometer. The ion peaks of acetone molecule appear at m/e=15 and 43, corresponding to the two fragments CH3+ and CH3CO+. It is considered that these two ions are, respectively, formed by direct (2+1) and 2-photon ionization of methyl and acetyl radicals, generated by photodissociation of acetone molecule.

Comparison of the effects of 665 nm low level diode Laser Hat versus and a combination of 665 nm and 808nm low level diode Laser Scanner of hair growth in androgenic alopecia.

Science.gov (United States)

Barikbin, Behrooz; Khodamrdi, Zeinab; Kholoosi, Leila; Akhgri, Mohammad Reza; Haj Abbasi, Majid; Hajabbasi, Mojgan; Razzaghi, Zahra; Akbarpour, Samaneh

2017-05-17

This study aimed to evaluate the effectiveness of a combined set of low level diode laser scanner (665 nm and 808nm) on hair growth, and assessment of safety and effectiveness of a new laser scanner on hair growth treatment procedure in androgenic alopecia. 90 patients (18 to 70 years) with androgenic alopecia were randomized into three groups. The first group (n=30) received 655 nm red light using laser hat, the second group (n=30) received 655 nm red laser plus 808 nm infrared laser using a laser scanner of hair growth device (with the patent number: 77733) and the third group (n=30) received no laser as the control group. Patients in laser scanner group had better results and showed a higher increase in terminal hair density compared with laser hat group (mean of 9.61 versus 9.16 per cm 2 ). We found significant decrease in terminal hair density from baseline in control group (mean -1.8 per cm 2 , plaser scanner of the hair growth group compared with laser hat and the control group. The study showed that treatment with new laser devise had a promising result without any observable adverse effects.

Correlation between cell survival and DNA single-strand break repair proficiency in the Chinese hamster ovary cell lines AA8 and EM9 irradiated with 365-nm ultraviolet-A radiation

Energy Technology Data Exchange (ETDEWEB)

Churchill, M.E.; Peak, J.G.; Peak, M.J. (Argonne National Lab., IL (USA))

1991-02-01

Cell survival parameters and the induction and repair of DNA single-strand breaks were measured in two Chinese hamster ovary cell lines after irradiation with monochromatic UVA radiation of wavelength 365 nm. The radiosensitive mutant cell line EM9 is known to repair ionizing-radiation-induced single-strand breaks (SSB) more slowly than the parent line AA8. EM9 was determined to be 1.7-fold more sensitive to killing by 365-nm radiation than AA8 at the 10% survival level, and EM9 had a smaller shoulder region on the survival curve ({alpha} = 1.76) than AA8 ({alpha} = 0.62). No significant differences were found between the cell lines in the initial yields of SSB induced either by {gamma}-radiation (as determined by alkaline sucrose gradient sedimentation) or by 365-nm UVA (as determined by alkaline elution). For measurement of initial SSB, cells were irradiated at 0.5{sup o}C to minimize DNA repair processes. Rejoining of 365-nm induced SSB was measured by irradiating cells at 0.5{sup o}C, allowing them to repair at 37{sup o}C in full culture medium, and then quantitating the remaining SSB by alkaline elution. The repair of these breaks followed biphasic kinetics in both cell lines. EM9 repaired the breaks more slowly (T{sub 1/2} values of 1.3 and 61.3 min) than did AA8 (T{sub 1/2} values of 0.9 and 53.3 min), and EM9 also left more breaks unrepaired 90 min after irradiation (24% vs 8% for AA8). Thus, the sensitivity of EM9 to 365-nm radiation correlated with its deficiency in repairing DNA lesions revealed as SSB in alkaline elution. These results suggest that DNA may be a critical target in 365-nm induced cellular lethality and that the ability of AA8 and EM9 cells to repair DNA strand breaks may be related to their ability to survive 365-nm radiation. (author).

Photosensitivity of the Er/Yb-Codoped Schott IOG1 Phosphate Glass Using 248 nm, Femtosecond, and Picosecond Laser Radiation

International Nuclear Information System (INIS)

Pissadakis, S.; Michelakaki, I.

2009-01-01

The effect of 248 nm laser radiation, with pulse duration of 5 picoseconds, 500 femtosecond, and 120 femtosecond, on the optical properties and the Knoop hardness of a commercial Er/Yb-codoped phosphate glass is presented here. Refractive index changes of the order of few parts of 10-4 are correlated with optical absorption centers induced in the glass volume, using Kramers-Kroning relationship. Accordingly, substantially lower refractive index changes are measured in volume Bragg gratings inscribed in the glass, indicating that, in addition to the optical density changes, volume dilation changes of negative sign may also be associated with the 248 nm ultrafast irradiation. The Knoop hardness experimental results reveal that the glass matrix undergoes an observable initial hardening and then a reversing softening and volume dilation process for modest accumulated energy doses, where the Knoop hardness follows a nonmonotonic trend. Comparative results on the Knoop hardness trend are also presented for the case of 193 nm excimer laser radiation. The above findings denote that the positive or negative evolution of refractive index changes induced by the 248 0nm ultrafast radiation in the glass is dominated by the counteraction of the color center formation and the volume modification effects.

Responses of phylloplane yeasts to UV-B (290-320 nm) radiation: interspecific differences in sensitivity

International Nuclear Information System (INIS)

Gunasekera, T.S.; Paul, N.D.; Ayres, P.G.

1997-01-01

The sensitivity to UV-B (290–320 nm) radiation of common phylloplane yeasts from two contrasting UV-B environments was compared in the laboratory using mixtures of white light (PAR: 400–700 nm) and UV-B radiation from artificial lamp sources. Sporidiobolus salmonicolor, Rhodotorula mucilaginosa and Cryptococcus sp., the dominant yeasts on leaves of tea (Camellia sinensis), were isolated in Sri Lanka (SL), while Sporidiobolus sp. and Bullera alba, dominant on faba bean (Vicia faba), were isolated in the U.K. Dose responses were determined separately for each yeast. UV-B reduced colony forming units (due to cell mortality or inactivation) and colony size (due to reduced multiplication) of all yeasts. The LD 50 values and doses causing 50% reduction of cells per colony were higher for SL isolates than U.K. isolates. Results indicated that each yeast is somewhat vulnerable to UV-B doses representative of its natural habitat. The relative insensitivity of SL isolates was shown when SL and U.K. isolates were irradiated simultaneously with the same dose of UV-B. Of the two U.K. yeasts, B. alba was significantly more sensitive than Sporidiobolus sp. to UV-B. Except for R. mucilaginosa from SL, all yeasts demonstrated some photorepair in the presence of white light. White light provided relatively little protection for the U.K. isolate of Sporidiobolus sp. although it allowed increased colony size. The spectral responses of Sporidiobolus sp. (U.K.) and of B. alba (U.K.) were broadly similar. Wavelengths longer than 320 nm had no measurable effect on colony forming units. However, colony survival was significantly reduced at 310 nm and all shorter wavebands. No colonies were counted at 290 nm or below. (author)

Measurement of the solar ultraviolet radiation at ground level in Bangi, Malaysia

Energy Technology Data Exchange (ETDEWEB)

Aljawi, Ohoud; Gopir, Geri; Duay, Abdul Basit [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia. ohoud-aljawi@hotmail.com (Malaysia)

2015-04-24

Understanding the amount of ultraviolet (UV) radiation received by human, plant, and animal organisms near the earth’s surface is important to a wide range of fields such as cancer research, agriculture and forestry. The solar ultraviolet spectral irradiance at ground level was measured using the Avantes spectrometer for the period of January to March 2014 at Bangi (2°55´N, 101°46´E, 50 m above sea level) in Malaysia. These data were used to estimate the diurnal variation of UV irradiance (300 – 400 nm). The maximum irradiance of UV radiation was 45 W m{sup −2} on horizontal surface. The maximum irradiance of UV received in the local noon time, and the minimum values of UV irradiance was received in the local morning time. It is found a bigger value of UV radiation was observed on clear sky in January. The estimation of daily flux average of UV irradiance was (921± 91) kJ m{sup −2}.

Radiative lifetime and Lande-factor measurements of the Se I 4p35S 5S2 level using pulsed laser spectroscopy

International Nuclear Information System (INIS)

Zerne, R.

1992-01-01

This diploma project consists of spectroscopic examinations of atomic selenium. Natural selenium was thermally dissociated in a quarts resonance cell keeping the background pressure of selenium molecules low by differential heating. The 4p 3 5S 5 S 2 level was excited by frequency-tripled pulsed dye-laser radiation at 207 nm. From time-resolved recording of the fluorescence decay at 216 nm the natural radiative lifetime of the 5 S 2 level was determined to be 493(15) ns. Quantum-beat and optical double resonance measurements in an external magnetic field yielded g j = 2.0004(10) for the Lande factor

Generation of 14  W at 589  nm by frequency doubling of high-power CW linearly polarized Raman fiber laser radiation in MgO:sPPLT crystal.

Science.gov (United States)

Surin, A A; Borisenko, T E; Larin, S V

2016-06-01

We introduce an efficient, single-mode, linearly polarized continuous wave (CW) Raman fiber laser (RFL), operating at 1178 nm, with 65 W maximum output power and a narrow linewidth of 0.1 nm. Single-pass second-harmonic generation was demonstrated using a 20 mm long MgO-doped stoichiometric periodically polled lithium tantalate (MgO:sPPLT) crystal pumped by RFL radiation. Output power of 14 W at 589 nm with 22% conversion efficiency was achieved. The possibility of further power scaling is considered, as no crystal degradation was observed at these power levels.

Repair of near-UV (365nm or 313 nm) induced DNA strand breaks

International Nuclear Information System (INIS)

Miguel, A.G.

1981-01-01

The action of near-UV (365 nm or 313 nm) radiation in cellular inactivaton (biological measurements) and induction and repair of breaks (physical measurements) is studied in repair proficient strain and in pol A, rec A and uvr A deficient strains of Escherichia coli K-12. (M.A.C.) [pt

Characterization of radiation effects in 65 nm digital circuits with the DRAD digital radiation test chip

International Nuclear Information System (INIS)

Casas, L.M. Jara; Ceresa, D.; Kulis, S.; Christiansen, J.; Francisco, R.; Miryala, S.; Gnani, D.

2017-01-01

A Digital RADiation (DRAD) test chip has been specifically designed to study the impact of Total Ionizing Dose (TID) (<1 Grad) and Single Event Upset (SEU) on digital logic gates in a 65 nm CMOS technology. Nine different versions of standard cell libraries are studied in this chip, basically differing in the device dimensions, V t flavor and layout of the device. Each library has eighteen test structures specifically designed to characterize delay degradation and power consumption of the standard cells. For SEU study, a dedicated test structure based on a shift register is designed for each library. TID results up to 500 Mrad are reported.

Comparative analysis of the effect of the GaAlAs laser irradiation in 780 nm and 660 nm in the hypersensitive dentin

International Nuclear Information System (INIS)

Yuan, Sun Chien

2003-01-01

This study was to evaluate and compare the effects of the low intensity in laser radiation among GaAlAs 780 nm and GaAlAs 660 nm. The main proposal is to verify if there is any difference of the effects or results in low intensity laser application treatment of hypersensitive dentin, keeping the same parameters, only differing in wavelength. The samples were distributed in two groups. Group A 90 cases, treated with GaAlAs 780 nm and group B irradiated with GaAlAs 660 nm with a total of 76 cases analyzed. The results of application with GaAlAs 660 nm and GaAlAs 780 nm do not differ statistically. Which means using any one of the irradiation gives the same results. However can be noted that the response of reduction of hypersensitivity is faster with the radiation of GaAlAs 780 nm, but the results after three applications is the same for both types of radiation. (author)

Comparison of Mg-based multilayers for solar He II radiation at 30.4 nm wavelength

Energy Technology Data Exchange (ETDEWEB)

Zhu Jingtao; Zhou Sika; Li Haochuan; Huang Qiushi; Wang Zhanshan; Le Guen, Karine; Hu, Min-Hui; Andre, Jean-Michel; Jonnard, Philippe

2010-07-10

Mg-based multilayers, including SiC/Mg, Co/Mg, B4C/Mg, and Si/Mg, are investigated for solar imaging and a He II calibration lamp at a 30.4 nm wavelength. These multilayers were fabricated by a magnetron sputtering method and characterized by x-ray reflection. The reflectivities of these multilayers were measured by synchrotron radiation. Near-normal-incidence reflectivities of Co/Mg and SiC/Mg multilayer mirrors are as high as 40.3% and 44.6%, respectively, while those of B4C/Mg and Si/Mg mirrors are too low for application. The measured results suggest that SiC/Mg, Co/Mg multilayers are promising for a 30.4 nm wavelength.

Effect of variable doses of ultraviolet radiation (253.7 nm) on thermoluminescence NaCl:Ca(T) material

International Nuclear Information System (INIS)

Nehate, A.K.; Joshi, T.R.; Kathuria, S.P.; Joshi, R.V.

1986-01-01

This paper studies the thermoluminescence (TL) glow curves of NaCl:Ca(T) phosphors to various doses of 253.7-nm ultraviolet (UV) radiation at room temperature. TLD grade NaCl:Ca(T) material was obtained by crystallization from solution and was subsequently annealed at 750 degrees C for 2 h, followed by sudden quenching. We undertook measurement of the effect of variable UV radiation doses (10(2) to 10(6) J m-2) on the TL behaviour of NaCl:Ca(T) phosphors. It was observed that the phosphor exhibits a dominant peak around 167 degrees C along with a weak peak at lower temperature. The high-temperature peak (Peak II) is found to grow linearly with the increase in UV dose in the range of 10(2) to 10(6) J m-2. Since the nature of the glow curves under the influence of different doses remains more or less identical, it is believed that the phosphor does not undergo radiation damage and displays high intrinsic TL around Peak II. Examination of the system for fundamental dosimetry requirements shows that it can be used in dosimetry work at 253.7 nm

Different (direct and indirect) mechanisms for the induction of DNA-protein crosslinks in human cells by far- and near-ultraviolet radiations (290 and 405 nm)

International Nuclear Information System (INIS)

Peak, M.J.; Peak, J.G.; Jones, C.A.

1985-01-01

Apparent DNA-protein crosslinking induced by monochromatic 290 and 405 nm radiations was measured in cultured human P3 teratocarcinoma cells with DNA alkaline elution techniques. The rates of the induction of crosslinks by 290 nm radiation were the same when the cells were irradiated either aerobically or anaerobically or when the cells were in an H 2 O or D 2 O aqueous environment. With 405 nm radiation, anaerobic irradiation reduced the induction of the crosslinks (dose modifying factor is about 0.2), and about twice as many crosslinks were observed when the cells were irradiated in an environment of D 2 O rather than H 2 O. The results are consistent with the hypothesis that far-UV radiation induces DNA-protein crosslinks by a direct mechanism, whereas near-UV radiation induces crosslinks via indirect photodynamic photosensitizations in which unidentified cellular endogenous photosensitizers and reactive species of oxygen are used. (author)

Forecasting noise and radiation hardness of CMOS front-end electronics beyond the 100 nm frontier

International Nuclear Information System (INIS)

Re, V.; Gaioni, L.; Manghisoni, M.; Ratti, L.; Traversi, G.

2010-01-01

The progress of industrial microelectronic technologies has already overtaken the 130 nm CMOS generation that is currently the focus of IC designers for new front-end chips in LHC upgrades and other detector applications. In a broader time span, sub-100 nm CMOS processes may become appealing for the design of very compact front-end systems with advanced integrated functionalities. This is especially true in the case of pixel detectors, both for monolithic devices (MAPS) and for hybrid implementations where a high resistivity sensor is connected to a CMOS readout chip. Technologies beyond the 100 nm frontier have peculiar features, such as the evolution of the device gate material to reduce tunneling currents through the thin dielectric. These new physical device parameters may impact on functional properties such as noise and radiation hardness. On the basis of experimental data relevant to commercial devices, this work studies potential advantages and challenges associated to the design of low-noise and rad-hard analog circuits in these aggressively scaled technologies.

Development of Radiation-hard Bandgap Reference and Temperature Sensor in CMOS 130 nm Technology

CERN Document Server

Kuczynska, Marika; Bugiel, Szymon; Firlej, Miroslaw; Fiutowski, Tomasz; Idzik, Marek; Michelis, Stefano; Moron, Jakub; Przyborowski, Dominik; Swientek, Krzysztof

2015-01-01

A stable reference voltage (or current) source is a standard component of today's microelectronics systems. In particle physics experiments such reference is needed in spite of harsh ionizing radiation conditions, i.e. doses exceeding 100 Mrads and fluences above 1e15 n/cm2. After such radiation load a bandgap reference using standard p-n junction of bipolar transistor does not work properly. Instead of using standard p-n junctions, two enclosed layout transistor (ELTMOS) structures are used to create radiation-hard diodes: the ELT bulk diode and the diode obtained using the ELTMOS as dynamic threshold transistor (DTMOS). In this paper we have described several sub-1V references based on ELTMOS bulk diode and DTMOS based diode, using CMOS 130 nm process. Voltage references the structures with additional PTAT (Proportional To Absolute Temperature) output for temperature measurements were also designed. We present and compare post-layout simulations of the developed bandgap references and temperature sensors, w...

Two-photon-excited fluorescence spectroscopy of atomic fluorine at 170 nm

Science.gov (United States)

Herring, G. C.; Dyer, Mark J.; Jusinski, Leonard E.; Bischel, William K.

1988-01-01

Two-photon-excited fluorescence spectroscopy of atomic fluorine is reported. A doubled dye laser at 286-nm is Raman shifted in H2 to 170 nm (sixth anti-Stokes order) to excite ground-state 2P(0)J fluorine atoms to the 2D(0)J level. The fluorine atoms are detected by one of two methods: observing the fluorescence decay to the 2PJ level or observing F(+) production through the absorption of an additional photon by the excited atoms. Relative two-photon absorption cross sections to and the radiative lifetimes of the 2D(0)J states are measured.

All-fiber femtosecond Cherenkov radiation source

DEFF Research Database (Denmark)

Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe

2012-01-01

-conversion medium, we demonstrate milliwatt-level, stable, and tunable Cherenkov radiation at visible wavelengths 580–630 nm, with pulse duration of sub-160-fs, and the 3 dB spectral bandwidth not exceeding 36 nm. Such an all-fiber Cherenkov radiation source is promising for practical applications in biophotonics...

Generation of 99-mW continuous-wave 285-nm radiation for magneto-optical trapping of Mg atoms

DEFF Research Database (Denmark)

Madsen, Dorte Nørgaard; Yu, Ping; Balslev, Søren

2002-01-01

We have developed a tunable intense narrow-band 285 nm light source based on frequency doubling of 570 nm light in BBO. At input powers of 840 mW (including 130 mW used for locking purposes) we generate 99 mW UV radiation with an intensity profile suitable for laser-cooling experiments. The light...... is used for laser cooling of neutral magnesium atoms in a magneto-optical trap (MOT). We capture about 5 x 10(6) atoms directly from a thermal beam and find that the major loss mechanism of the magnesium MOT is a near-resonant two-photon ionization process....

Radiation Level Changes at RAM Package Surfaces

Energy Technology Data Exchange (ETDEWEB)

Opperman, Erich [Washington Savannah River Company; Hawk, Mark B [ORNL; Kapoor, Ashok [U.S. Department of Energy, Office of Packaging and Transportation; Natali, Ronald [R. B. Natali Consulting, Inc.

2010-01-01

This paper will explore design considerations required to meet the regulations that limit radiation level variations at external surfaces of radioactive material (RAM) packages. The radiation level requirements at package surfaces (e.g. TS-R-1 paragraphs 531 and 646) invoke not only maximum radiation levels, but also strict limits on the allowable increase in the radiation level during transport. This paper will explore the regulatory requirements by quantifying the amount of near surface movement and/or payload shifting that results in a 20% increase in the radiation level at the package surface. Typical IP-2, IP-3, Type A and Type B packaging and source geometries will be illustrated. Variations in surface radiation levels are typically the result of changes in the geometry of the surface due to an impact, puncture or crush event, or shifting and settling of radioactive contents.

Nitrogen capillary plasma as a source of intense monochromatic radiation at 2.88 nm

Energy Technology Data Exchange (ETDEWEB)

Vrba, P., E-mail: vrbovmir@fbmi.cvut.cz [Institute of Plasma Physics, Academy of Sciences, Za Slovankou 3, Prague 8 (Czech Republic); Vrbova, M. [Faculty of Biomedical Engineering, CTU in Prague, Sitna 3105, Kladno 2 (Czech Republic); Zakharov, S.V. [EPPRA sas, Villebon/Yvette (France); Zakharov, V.S. [EPPRA sas, Villebon/Yvette (France); KIAM RAS, Moscow (Russian Federation); Jancarek, A.; Nevrkla, M. [Faculty of Nuclear Science and Physical Engineering, CTU in Prague, Brehova 7, Prague 1 (Czech Republic)

2014-10-15

Highlights: • Pinching capillary discharge is studied as a source of monochromatic SXR. • Modeling of the laboratory device was performed by RMHD Z* code. • Results of computer and laboratory experiments are presented. - Abstract: Capillary discharge plasma related to our laboratory device is modeled and the results are compared with experimental data. Time dependences of selected plasma quantities (e.g. plasma mass density, electron temperature and density and emission intensities) evaluated by 2D Radiation-Magneto-Hydro-Dynamic code Z* describe plasma evolution. The highest output pulse energy at 2.88 nm wavelength is achieved for nitrogen filling pressure ∼100 Pa. The estimated output energy of monochromatic radiation 5.5 mJ sr{sup −1} (∼10{sup 14} photons sr{sup −1}) corresponds properly to observe experimental value ∼3 × 10{sup 13} photons sr{sup −1}. Ray tracing inspection along the capillary axis proves an influence of radiation self-absorption for the investigated wavelength. The spectra, evaluated using the FLY code, agree to the measured ones.

Picosecond laser texturization of mc-silicon for photovoltaics: A comparison between 1064 nm, 532 nm and 355 nm radiation wavelengths

Energy Technology Data Exchange (ETDEWEB)

Binetti, Simona [Department of Materials Science and Milano-Bicocca Solar Energy Research Center (MIB-SOLAR), University of Milano-Bicocca, Via Cozzi 55, 20125 Milano (Italy); Le Donne, Alessia, E-mail: alessia.ledonne@mater.unimib.it [Department of Materials Science and Milano-Bicocca Solar Energy Research Center (MIB-SOLAR), University of Milano-Bicocca, Via Cozzi 55, 20125 Milano (Italy); Rolfi, Andrea [Department of Materials Science and Milano-Bicocca Solar Energy Research Center (MIB-SOLAR), University of Milano-Bicocca, Via Cozzi 55, 20125 Milano (Italy); Jäggi, Beat; Neuenschwander, Beat [Bern University of Applied Sciences, Engineering and Information Technology, Institute for Applied Laser, Photonics and Surface Technologies ALPS, Pestalozzistrasse 20, CH-3400 Burgdorf (Switzerland); Busto, Chiara [ENI Spa, Via Giacomo Fauser, 4, 28100 Novara (Italy); Frigeri, Cesare [CNR-IMEM Institute, Parco Area Delle Scienze 37/A, Fontanini, 43010 Parma (Italy); Scorticati, Davide; Longoni, Luca; Pellegrino, Sergio [Laserpoint Srl, Via Della Burrona 51, 20090 Vimodrone, Milano (Italy)

2016-05-15

Highlights: • Self-organized surface structures were produced by picosecond laser pulses on mc-Si. • Three laser wavelengths were used which effectively reduce Si reflectivity up to 8%. • The subsurface damage induced by the three lasers was studied in detail. • μ-Raman, PL and TEM proved that UV laser provides the lowest subsurface damage. • UV laser induced damage is located above the depletion region of the p–n junction. - Abstract: Self-organized surface structures were produced by picosecond laser pulses on multi-crystalline silicon for photovoltaic applications. Three different laser wavelengths were employed (i.e. 1064 nm, 532 nm and 355 nm) and the resulting morphologies were observed to effectively reduce the reflectivity of the samples after laser irradiation. Besides, a comparative study of the laser induced subsurface damage generated by the three different wavelengths was performed by confocal micro-Raman, photoluminescence and transmission electron microscopy. The results of both the structural and optical characterization showed that the mc-Si texturing performed with the laser at 355 nm provides surface reflectivity between 11% and 8% over the spectral range from 400 nm to 1 μm, while inducing the lowest subsurface damage, located above the depletion region of the p–n junction.

A Monolithic Active Pixel Sensor for ionizing radiation using a 180 nm HV-SOI process

Energy Technology Data Exchange (ETDEWEB)

Hemperek, Tomasz, E-mail: hemperek@uni-bonn.de; Kishishita, Tetsuichi; Krüger, Hans; Wermes, Norbert

2015-10-01

An improved SOI-MAPS (Silicon On Insulator Monolithic Active Pixel Sensor) for ionizing radiation based on thick-film High Voltage SOI technology (HV-SOI) has been developed. Similar to existing Fully Depleted SOI-based (FD-SOI) MAPS, a buried silicon oxide inter-dielectric (BOX) layer is used to separate the CMOS electronics from the handle wafer which is used as a depleted charge collection layer. FD-SOI MAPS suffers from radiation damage such as transistor threshold voltage shifts due to charge traps in the oxide layers and charge states created at the silicon oxide boundaries (back gate effect). The X-FAB 180-nm HV-SOI technology offers an additional isolation by deep non-depleted implant between the BOX layer and the active circuitry which mitigates this problem. Therefore we see in this technology a high potential to implement radiation-tolerant MAPS with fast charge collection property. The design and measurement results from a first prototype are presented including charge collection in neutron irradiated samples.

Autonomous portable solar ultraviolet spectroradiometer (APSUS) - a new CCD spectrometer system for localized, real-time solar ultraviolet (280-400 nm) radiation measurement.

Science.gov (United States)

Hooke, Rebecca; Pearson, Andy; O'Hagan, John

2014-01-01

Terrestrial solar ultraviolet (UV) radiation has significant implications for human health and increasing levels are a key concern regarding the impact of climate change. Monitoring solar UV radiation at the earth's surface is therefore of increasing importance. A new prototype portable CCD (charge-coupled device) spectrometer-based system has been developed that monitors UV radiation (280-400 nm) levels at the earth's surface. It has the ability to deliver this information to the public in real time. Since the instrument can operate autonomously, it is called the Autonomous Portable Solar Ultraviolet Spectroradiometer (APSUS). This instrument incorporates an Ocean Optics QE65000 spectrometer which is contained within a robust environmental housing. The APSUS system can gather reliable solar UV spectral data from approximately April to October inclusive (depending on ambient temperature) in the UK. In this study the new APSUS unit and APSUS system are presented. Example solar UV spectra and diurnal UV Index values as measured by the APSUS system in London and Weymouth in the UK in summer 2012 are shown. © 2014 Crown copyright. Photochemistry and Photobiology © 2014 The American Society of Photobiology. This article is published with the permission of the Controller of HMSO and the Queen's Printer for Scotland and Public Health England.

Repair of 313-nm induced lesions and photoprotection in yeast Candida guilliermondii

International Nuclear Information System (INIS)

Fraikin, G.Y.; Pospelov, M.E.; Rubin, L.B.

1977-01-01

The present communication is concerned with the effects of near-UV radiation (300-380 nm) on yeast Candida guilliermondii. It was found that certain doses of 313 nm irradiation caused inactivation of the yeast which was exhibited in a way different from the lethal action of far-UV radiation. It was also found that the cells inactivated by 313 nm are capable of recovering vitality, if incubated for some time in a non-nutrient medium. The yeast inactivated by far-UV radiation also proved to be capable of recovering, though to a lesser degree. Both 334 nm radiation and non-lethal doses at 313 nm induced the photoprotective effect against far-UV damage. The effect was exhibited if there was a certain time interval (2-4 h) between the exposures to photoprotective light and subsequent far-UV radiation. Within this time interval the extent of photoprotection was dependent on temperature. (author)

Acceptance criteria for deposition of low-level and intermediate-level radiation levels radioactive wastes

International Nuclear Information System (INIS)

2002-09-01

This norm establishes the criteria for acceptance low and intermediate radiation level for safe deposition in repositories, for assuring the protection of workers, population and environment against the hazardous effects of the ionizing radiations. The criteria of this norm applies to the low and intermediate radiation levels

Radiation hardness evaluation of the commercial 150 nm CMOS process using 60Co source

International Nuclear Information System (INIS)

Carna, M; Havranek, M; Hejtmanek, M; Janoska, Z; Marcisovsky, M; Neue, G; Tomasek, L; Vrba, V

2014-01-01

We present a study of radiation effects on MOSFET transistors irradiated with a 60 Co source to a total absorbed dose of 1.5 Mrad. The transistor test structures were manufactured using a commercial 150 nm CMOS process and are composed of transistors of different types (NMOS and PMOS), dimensions and insulation from the bulk material by means of deep n-wells. We have observed a degradation of electrical characteristics of both PMOS and NMOS transistors, namely a large increase of the leakage current of the NMOS transistors after irradiation

Environment and health: 3. Ozone depletion and ultraviolet radiation

International Nuclear Information System (INIS)

De Gruijl, F.R.; Van der Leun, J.C.

2000-01-01

Ultraviolet radiation from the sun is responsible for a variety of familiar photochemical reactions, including photochemical smog, bleaching of paints and decay of plastics. Conjugated bonds in organic molecules such as proteins and DNA absorb the UV radiation, which can damage these molecules. By a fortunate evolutionary event, the oxygen produced by photosynthesis forms a filter in the outer reaches of our atmosphere that absorbs the most energetic and harmful UV radiation, with wavelengths below 240 nm (in the UVC band [wavelength 100-280 nm]). In the process, the oxygen molecules split up and recombine to form ozone (Fig. 1). This ratified ozone layer (spread out between 10 and 50 Ion in the stratosphere but only 3 mm thick were it compressed at ground level) in turn efficiently absorbs UV radiation of higher wavelengths (tip to about 310 nm). A part of the UV radiation in the UVB band (wavelength 280-315 nm) still reaches ground level and is absorbed in sufficient amounts to have deleterious effects on cells. The less energetic radiation in the UVA band (wavelength 315-400 nm, bordering the visible band [wavelength 400-800 nm]) is not absorbed by ozone and reaches ground level without much attenuation through a clear atmosphere (i.e., no clouds, no air pollution). Although not completely innocuous, the UVA radiation in sunlight is much less photochemically active and therefore generally less harmful than UVB radiation. Life on earth has adapted itself to the UV stress, particularly UVB stress, fbr example by forming protective UV-absorbing surface layers, by repairing cell damage or by replacing damaged cells entirely. Human skin shows all of these adaptive features. Our eyes are less well adapted, but dicy, are shielded by the brows and by squinting. (author)

[The influence of pulsed low-intensity laser radiation of the red (635 nm) and infrared (904 nm) spectra on the human mesenchymal stem cells in vitro].

Science.gov (United States)

Moskvin, S V; Kliuchnikov, D Iu; Antipov, E V; Volchkov, S E; Kiseleva, O N

2014-01-01

Mesenchymal stem cells (MSC) have for a long time been an object of investigation with a view to elucidating the prospects for their application in clinical medicine and cosmetology. One of the approaches to the non-specific regulation of the activity of these cells at the stage of preliminary in vitro combination is the treatment with low-intensity laser radiation (LILR). The objective of the present study was to evaluate the possibility of using pulsed LILR of the infrared and red spectra for this purpose. We used the 4th passage adhesive MSC cultures based at the umbilical tissue of a donor who gave the informed consent to participate in the study. The source of illumination was a Lazmik-VLOK laser therapeutic apparatus (RU No RZN 2014/1410 dated 06.02.2014) with the matrix laser infrared radiation heads (wavelength 904 nm, light pulse length 108 ns, frequency 1500 Hz). The apparatus was operated either in the multi-frequency Lazmik regime [Moskvin S.V., 2014] with mean power density 0.05 and 0.14 mW/cm2 and the red spectrum (wavelength 635 nm, light pulse length 144 ns, frequency 1500 Hz) or in the multi-frequency Lazmik regime [Moskvin S.V., 2014] with mean power density 0.03 and 0.12. The exposition was 5 min in both regimes. The study has demonstrated that neither the morphological structure nor the viability of mesenchymal stem cells changed under the influence of energy and time parameters used in experiments. The number of cells was shown to slightly increase in comparison with control. The most pronounced effect was documented after illumination with pulse infrared (904 nm) LILR in the multi-frequency Lazmik regime. The maximum effect was observed during a period between days 1 and 3 of cultivation.

SGR-76 gamma radiation level indicator

International Nuclear Information System (INIS)

Chubinskij-Nadezhdin, I.V.

1978-01-01

The design of a gamma-radiation level indicator is described; the instrument is part of a mobile radiometric laboratory (MRL). The design of the instrument permits gamma-radiation dose rates recording at 0.2-200 R/hr, and signals on gamma-background levels. The instrument has two separate threshold levels of signalling actuation. The light signalling at the first level is precautionary, and the sound signalling at the second level indicates the necessity of taking a decision as to whether or not the MRL can remain in the gamma-radiation field. Halogenic counters operating in a current mode are used as detectors. The basic error in recording the dose rate amounts to +-25%. Overall dimensions of the instrument 150x280x100 mm; weight less than 2.5 kg

The cause of spatial structure in solar He I 1083 nm multiplet images

Science.gov (United States)

Leenaarts, Jorrit; Golding, Thomas; Carlsson, Mats; Libbrecht, Tine; Joshi, Jayant

2016-10-01

Context. The He I 1083 nm is a powerful diagnostic for inferring properties of the upper solar chromosphere, in particular for the magnetic field. The basic formation of the line in one-dimensional models is well understood, but the influence of the complex three-dimensional structure of the chromosphere and corona has however never been investigated. This structure must play an essential role because images taken in He I 1083 nm show structures with widths down to 100 km. Aims: We aim to understand the effect of the three-dimensional temperature and density structure in the solar atmosphere on the formation of the He I 1083 nm line. Methods: We solved the non-LTE radiative transfer problem assuming statistical equilibrium for a simple nine-level helium atom that nevertheless captures all essential physics. As a model atmosphere we used a snapshot from a 3D radiation-MHD simulation computed with the Bifrost code. Ionising radiation from the corona was self-consistently taken into account. Results: The emergent intensity in the He I 1083 nm is set by the source function and the opacity in the upper chromosphere. The former is dominated by scattering of photospheric radiation and does not vary much with spatial location. The latter is determined by the photonionisation rate in the He I ground state continuum, as well as the electron density in the chromosphere. The spatial variation of the flux of ionising radiation is caused by the spatially-structured emissivity of the ionising photons from material at T ≈ 100 kK in the transition region. The hotter coronal material produces more ionising photons, but the resulting radiation field is smooth and does not lead to small-scale variation of the UV flux. The corrugation of the transition region further increases the spatial variation of the amount of UV radiation in the chromosphere. Finally we find that variations in the chromospheric electron density also cause strong variation in He I 1083 nm opacity. We compare our

Can low-level radiation cause cancer?

International Nuclear Information System (INIS)

Trosko, J.E.

1995-01-01

Health in a multicellular organism is maintained by homeostatic processes. Disruption of these homeostatic controls at the molecular, biochemical, cellular, and organ systems levels can be brought about by irreversible changes in the genetic material (mutagenesis), cell death (cytotoxicity), or reversible changes in the expression of genes at the transcriptional, translational, or posttranslational levels (epigenesis). While radiation is known to induce DNA damage/mutations, cell, death and epigenetic changes, in addition to cancers that are found in radiation-exposed animals, experimentally, and in humans, epidemiologically, the question is, At low-level exposure, what is the risk that cancers are open-quotes causedclose quotes by the radiation?

Course of radiation protection: technical level

International Nuclear Information System (INIS)

2002-01-01

The course handbook on radiation protection and nuclear safety, technical level prepared by scientists of the Nuclear Regulatory Authority (ARN) of the Argentina Republic, describes the subjects in 19 chapters and 2 annexes. These topics detailed in the text have the following aspects: radioactivity elements, interaction of the radiation and the matter, radio dosimetry, internal contamination dosimetry, principles of radiation detection, biological radiation effects, fundamentals of radiation protection, dose limits, optimization, occupational exposure, radiation shielding, radioactive waste management, criticality accidents, safe transport of radioactive materials, regulatory aspects

Mechanistic comparison of pulse laser induced phase separation of particulates from cellulose paper at 213 nm and 532 nm

International Nuclear Information System (INIS)

Arif, S.; Forster, M.; Kautek, W.; Bushuk, S.; Kouzmouk, A.; Tatur, H.; Batishche, S.

2013-01-01

The laser-induced phase separation of charcoal particles on additive-free cotton linters cellulose paper was investigated by electron and optical microscopy, colorimetry, and diffuse reflectance FT-IR. The fibre bundles were vaporised in depth of several 10 μm above destruction fluence thresholds using visible 532 nm radiation. This is in contrast to mid-ultraviolet 213 nm radiation, where only the top fibre bundles were modified and partially evaporated. The colorimetric lightness results generally represented the cleaning status, whereas the colorimetric yellowing data represented irreversible chemical and/or photochemical changes. Charcoal-contaminated paper treated with visible and mid-ultraviolet radiation exhibited yellowing, whereas uncontaminated did not. This suggests that the electron-rich plasma generated by the evaporation of the particles heats the adjacent substrate and also excludes oxygen. Mid-ultraviolet, in contrast to visible radiation, shows particle removal always accompanied by paper destruction. IR spectroscopy results suggest cross-linking by ether bonds near the destruction threshold, but do not prove the formation of oxidation products and double bonds as the basis of the yellowing. A ''cleaning window'' between the cleaning threshold (0.1 J/cm 2 ) and the paper destruction threshold (2.9 J/cm 2 ) with a pulse number of 2 is provided by visible 532 nm laser treatment. (orig.)

Response of sugar beet plants to ultraviolet-B (280-320 nm) radiation and Cercospora leaf spot disease

International Nuclear Information System (INIS)

Panagopoulos, I.; Bornman, J.F.; Björn, L.O.

1992-01-01

Sugar beet (Beta vulgaris L.) plants injected with Cercospora beticola Sacc. as well as non-infected plants were grown under visible light with or without ultraviolet-B (UV-B, 280-320 nm) radiation for 40 days. An interaction between UV-B radiation and Cercospora leaf spot disease was observed, resulting in a large reduction in leaf chlorophyll content, dry weight of leaf laminae, petioles and storage roots. Lipid peroxidation in leaves also increased the most under the combined treatments. This was also true for ultraweak luminescence from both adaxial and abaxial leaf surfaces. However, no correlation between lipid peroxidation and ultraweak luminescence was observed. Ultraviolet-B radiation given alone appeared to have either a stimulating effect, giving an increase in dry weight of laminac and reducing lipid peroxidation, or no effect. This lack of effect was seen in the absence of change in dry weight of storage roots and chlorophyll content relative to controls. The study demonstrated a harmful interaction between UV-B radiation and Cercospora leaf spot disease on sugar beet

Low level radiation: biological effects

International Nuclear Information System (INIS)

Loken, M.K.

1983-01-01

It is imperative that physicians and scientists using radiations in health care delivery continue to assess the benefits derived, vs. potential risk, to patients and radiation workers being exposed to radiation in its various forms as part of our health delivery system. Insofar as possible we should assure our patients and ourselves that the benefits outweigh the potential hazards involved. Inferences as to the possible biological effects of low level radiation are generally based on extrapolations from those effects observed and measured following acute exposures to considerably higher doses of radiation. Thus, in order to shed light on the question of the possible biological effects of low level radiation, a wide variety of studies have been carried out using cells in culture and various species of plant and animal life. This manuscript makes reference to some of those studies with indications as to how and why the studies were done and the conclusions that might be drawn there from. In addition reference is made to the handling of this information by scientists, by environmentalists, and by the news media. Unfortunately, in many instances the public has been misled by what has been said and/or written. It is hoped that this presentation will provide an understandable and reasonable perspective on the various appropriate uses of radiation in our lives and how such uses do provide significant improvement in our health and in our quality of life

Application and possible mechanisms of combining LLLT (low level laser therapy), infrared hyperthermia and ionizing radiation in the treatment of cancer

Science.gov (United States)

Abraham, Edward H.; Woo, Van H.; Harlin-Jones, Cheryl; Heselich, Anja; Frohns, Florian

2014-02-01

Benefit of concomitant infrared hyperthermia and low level laser therapy and ionizing radiation is evaluated in this study. The purpose/objectives: presentation with locally advanced bulky superficial tumors is clinically challenging. To enhance the efficacy of chemotherapy and IMRT (intensity-modulated radiation therapy) and/or electron beam therapy we have developed an inexpensive and clinically effective infrared hyperthermia approach that combines black-body infrared radiation with halogen spectrum radiation and discrete wave length infrared clinical lasers LLLT. The goal is to produce a composite spectrum extending from the far infrared to near infrared and portions of the visible spectrum with discrete penetrating wavelengths generated by the clinical infrared lasers with frequencies of 810 nm and/or 830 nm. The composite spectrum from these sources is applied before and after radiation therapy. We monitor the surface and in some cases deeper temperatures with thermal probes, but use an array of surface probes as the limiting safe thermal constraint in patient treatment while at the same time maximizing infrared entry to deeper tissue layers. Fever-grade infrared hyperthermia is produced in the first centimeters while non-thermal infrared effects act at deeper tissue layers. The combination of these effects with ionizing radiation leads to improved tumor control in many cancers.

Background radiation levels and standards for protection from ionizing radiations

International Nuclear Information System (INIS)

Farai, I.

1999-01-01

Apart from the amount of radiation which a worker may receive while he performs his work, he is also exposed to radiation because of the nature of his environment. In other words, all individuals are subject to some irradiation even though they may not work with radioactive substances. This source of radiation exposure is often referred to as background radiation. In most environments, it is low-level and can be grouped into two natural and man-made. Background radiation provides the basis on which allowable exposure limits for workers are drawn

Generation of continuous-wave 194 nm laser for mercury ion optical frequency standard

Science.gov (United States)

Zou, Hongxin; Wu, Yue; Chen, Guozhu; Shen, Yong; Liu, Qu; Precision measurement; atomic clock Team

2015-05-01

194 nm continuous-wave (CW) laser is an essential part in mercury ion optical frequency standard. The continuous-wave tunable radiation sources in the deep ultraviolet (DUV) region of the spectrum is also serviceable in high-resolution spectroscopy with many atomic and molecular lines. We introduce a scheme to generate continuous-wave 194 nm radiation with SFM in a Beta Barium Borate (BBO) crystal here. The two source beams are at 718 nm and 266 nm, respectively. Due to the property of BBO, critical phase matching (CPM) is implemented. One bow-tie cavity is used to resonantly enhance the 718 nm beam while the 266 nm makes a single pass, which makes the configuration easy to implement. Considering the walk-off effect in CPM, the cavity mode is designed to be elliptical so that the conversion efficiency can be promoted. Since the 266 nm radiation is generated by a 532 nm laser through SHG in a BBO crystal with a large walk-off angle, the output mode is quite non-Gaussian. To improve mode matching, we shaped the 266 nm beam into Gaussian modes with a cylindrical lens and iris diaphragm. As a result, 2.05 mW 194 nm radiation can be generated. As we know, this is the highest power for 194 nm CW laser using SFM in BBO with just single resonance. The work is supported by the National Natural Science Foundation of China (Grant No. 91436103 and No. 11204374).

Radiation levels on empty cylinders containing heel material

Energy Technology Data Exchange (ETDEWEB)

Shockley, C.W. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

1991-12-31

Empty UF{sub 6} cylinders containing heel material were found to emit radiation levels in excess of 200 mr/hr, the maximum amount stated in ORO-651. The radiation levels were as high as 335 mr/hr for thick wall (48X and 48Y) cylinders and 1050 mr/hr for thin wall (48G and 48H) cylinders. The high readings were found only on the bottom of the cylinders. These radiation levels exceeded the maximum levels established in DOT 49 CFR, Part 173.441 for shipment of cylinders. Holding periods of four weeks for thick-wall cylinders and ten weeks for thin-wall cylinders were established to allow the radiation levels to decay prior to shipment.

Radiation-Induced Short Channel (RISCE) and Narrow Channel (RINCE) Effects in 65 and 130 nm MOSFETs

CERN Document Server

Faccio, F; Cornale, D; Paccagnella, A; Gerardin, S

2015-01-01

The behavior of transistors in commercial-grade complementary metal-oxide semiconductor technologies in the 65 and 130 nm nodes has been explored up to a total ionizing dose of 1 Grad. The large dose tolerance of the thin gate oxide is confirmed, but defects in the spacer and STI oxides have a strong effect on the performance of the transistors. A radiation-induced short channel effect is traced to charge trapping in the spacers used for drain engineering, while a radiation-induced narrow channel effect is due to defect generation in the lateral isolation oxide (STI). These strongly degrade the electrical characteristics of short and narrow channel transistors at high doses, and their magnitude depends on the applied bias and temperature during irradiation in a complex way.

Mechanistic comparison of pulse laser induced phase separation of particulates from cellulose paper at 213 nm and 532 nm

Energy Technology Data Exchange (ETDEWEB)

Arif, S.; Forster, M.; Kautek, W. [University of Vienna, Department of Physical Chemistry, Wien (Austria); Bushuk, S.; Kouzmouk, A.; Tatur, H.; Batishche, S. [National Academy of Sciences of the Republic of Belarus, Institute of Physics, Minsk (Belarus)

2013-02-15

The laser-induced phase separation of charcoal particles on additive-free cotton linters cellulose paper was investigated by electron and optical microscopy, colorimetry, and diffuse reflectance FT-IR. The fibre bundles were vaporised in depth of several 10 {mu}m above destruction fluence thresholds using visible 532 nm radiation. This is in contrast to mid-ultraviolet 213 nm radiation, where only the top fibre bundles were modified and partially evaporated. The colorimetric lightness results generally represented the cleaning status, whereas the colorimetric yellowing data represented irreversible chemical and/or photochemical changes. Charcoal-contaminated paper treated with visible and mid-ultraviolet radiation exhibited yellowing, whereas uncontaminated did not. This suggests that the electron-rich plasma generated by the evaporation of the particles heats the adjacent substrate and also excludes oxygen. Mid-ultraviolet, in contrast to visible radiation, shows particle removal always accompanied by paper destruction. IR spectroscopy results suggest cross-linking by ether bonds near the destruction threshold, but do not prove the formation of oxidation products and double bonds as the basis of the yellowing. A ''cleaning window'' between the cleaning threshold (0.1 J/cm{sup 2}) and the paper destruction threshold (2.9 J/cm{sup 2}) with a pulse number of 2 is provided by visible 532 nm laser treatment. (orig.)

Ultraviolet radiation in Finland

Energy Technology Data Exchange (ETDEWEB)

Taalas, P; Koskela, T; Damski, J; Supperi, A [Finnish Meteorological Inst., Helsinki (Finland). Section of Ozone and UV Research; Kyroe, E [Finnish Meteorological Inst., Sodankylae (Finland). Sodankylae Observatory

1997-12-31

Solar ultraviolet radiation is damaging for living organisms due to its high energy pro each photon. The UV radiation is often separated into three regions according to the wavelength: UVC (200-280 nm), UVB (280-320 nm) and UVA (320-400 nm). The most hazardous part, UVC is absorbed completely in the upper atmosphere by molecular oxygen. UVB radiation is absorbed by atmospheric ozone partly, and it is reaching Earth`s surface, as UVA radiation. Besides atmospheric ozone, very important factors in determining the intensity of UVB radiation globally are the solar zenith angle and cloudiness. It may be calculated from global ozone changes that the clear-sky UVB doses may have enhanced by 10-15 % during spring and 5-10 % during summer at the latitudes of Finland, following the decrease of total ozone between 1979-90. The Finnish ozone and UV monitoring activities have become a part of international activities, especially the EU Environment and Climate Programme`s research projects. The main national level effort has been the Finnish Academy`s climatic change programme, SILMU 1990-95. This presentation summarises the scientific results reached during the SILMU project

Ultraviolet radiation in Finland

Energy Technology Data Exchange (ETDEWEB)

Taalas, P.; Koskela, T.; Damski, J.; Supperi, A. [Finnish Meteorological Inst., Helsinki (Finland). Section of Ozone and UV Research; Kyroe, E. [Finnish Meteorological Inst., Sodankylae (Finland). Sodankylae Observatory

1996-12-31

Solar ultraviolet radiation is damaging for living organisms due to its high energy pro each photon. The UV radiation is often separated into three regions according to the wavelength: UVC (200-280 nm), UVB (280-320 nm) and UVA (320-400 nm). The most hazardous part, UVC is absorbed completely in the upper atmosphere by molecular oxygen. UVB radiation is absorbed by atmospheric ozone partly, and it is reaching Earth`s surface, as UVA radiation. Besides atmospheric ozone, very important factors in determining the intensity of UVB radiation globally are the solar zenith angle and cloudiness. It may be calculated from global ozone changes that the clear-sky UVB doses may have enhanced by 10-15 % during spring and 5-10 % during summer at the latitudes of Finland, following the decrease of total ozone between 1979-90. The Finnish ozone and UV monitoring activities have become a part of international activities, especially the EU Environment and Climate Programme`s research projects. The main national level effort has been the Finnish Academy`s climatic change programme, SILMU 1990-95. This presentation summarises the scientific results reached during the SILMU project

Quasi-three-level thin-disk laser at 1024 nm based on diode-pumped Yb:YAG crystal

International Nuclear Information System (INIS)

Wang, A G; Li, Y L; Fu, X H

2011-01-01

We present for the first time, to the best of our knowledge, a Yb:YAG laser operating in a continuous wave (CW) on the quasi-three-level laser at 1024 nm, based on the 2 F 5/2 – 2 F 7/2 transition, generally used for a 1030 nm emission. The use of a pump module with 16 passes through the crystal allowed the realization of a Yb:YAG thin-disk laser with 370 mW of CW output power at 1024 nm. Moreover, intracavity second-harmonic generation (SHG) has also been achieved with a power of 45 mW at 512 nm by using a LiB 3 O 5 (LBO) nonlinear crystal

Radiation from an equilibrium CO2-N2 plasma in the [250-850 nm] spectral region: II. Spectral modelling

International Nuclear Information System (INIS)

Silva, M Lino da; Vacher, D; Andre, P; Faure, G; Dudeck, M

2008-01-01

In the first part of this work, described in a previous paper, the thermodynamic conditions in an atmospheric pressure inductively coupled CO 2 -N 2 plasma have been determined, and the radiation emission spectrum has been measured and calibrated in the [250-850 nm] spectral region. In the second part of this work, a synthetic radiation spectrum is obtained taking into account (a) the geometry of the plasma torch and (b) the local thermodynamic conditions of the plasma. This synthetic spectrum has then been compared against the measured spectrum. The good agreement between the two spectra allows validating the spectral database of the line-by-line code SPARTAN for the simulation of the radiative emission of CO 2 -N 2 plasmas from the near-UV to the near-IR spectral region.

Responses to the low-level-radiation controversy

International Nuclear Information System (INIS)

Bond, V.P.

1981-01-01

Some data sets dealing with the hazards of low-level radiation are discussed. It is concluded that none of these reports, individually or collectively, changes appreciably or even significantly the evaluations of possible low-level radiation effects that have been made by several authoritative national and international groups

Radiation hormesis: an outcome of exposure to low level ionizing radiation

International Nuclear Information System (INIS)

Kant, Krishan

2012-01-01

Ionizing radiation is a benign environmental agent at background levels. Human population is always exposed to ionizing radiation from natural sources. Important sources are cosmic rays which come from outer space and from the surface of the sun, terrestrial radionuclides which occur in the earths crust in various geological formations in soils, rocks, building materials, plants, water, food, air and in the human body itself. With the increasing use of radiation in health facilities, scientific research, industry and agriculture, the study of impact of low-level ionizing radiation on environment and possible health effects on future generations has been a cause of concern in recent years. As regards the effects, it is established fact that high doses of ionizing radiation are harmful to health, there exists, however, a substantial controversy regarding the effects of low doses of ionizing radiation (LLIR). In the present paper, brief review of the available literature, data and reports on stimulation by low-dose irradiation and recent data supporting radiation hormesis. A linear quadratic model has been given illustrating the validity of radiation hormesis, besides the comparison of the dose rates arising from natural and manmade sources to the Indian population. This overview summarizes various reports

Prototyping the HPDP Chip on STM 65 NM Process

Science.gov (United States)

Papadas, C.; Dramitinos, G.; Syed, M.; Helfers, T.; Dedes, G.; Schoellkopf, J.-P.; Dugoujon, L.

2011-08-01

Currently Astrium GmbH is involved in the of the High Performance Data Processor (HPDP) development programme for telecommunication applications under a DLR contract. The HPDP project targets the implementation of the commercially available reconfigurable array processor IP (XPP from the company PACT XPP Technologies) in a radiation hardened technology.In the current complementary development phase funded under the Greek Industry Incentive scheme, it is planned to prototype the HPDP chip in commercial STM 65 nm technology. In addition it is also planned to utilise the preliminary radiation hardened components of this library wherever possible.This abstract gives an overview of the HPDP chip architecture, the basic details of the STM 65 nm process and the design flow foreseen for the prototyping. The paper will discuss the development and integration issues involved in using the STM 65 nm process (also including the available preliminary radiation hardened components) for designs targeted to be used in space applications.

Animal model for evaluation of topical photoprotection against ultraviolet A (320-380 nm) radiation

International Nuclear Information System (INIS)

Chew, S.; DeLeo, V.A.; Harber, L.C.

1987-01-01

Recent studies reporting UVA (ultraviolet A radiation 320-380 nm) as an integral part of the cumulative sun-induced damage in human skin have prompted an interest in developing effective UVA photoprotective agents. The development of such compounds has been impeded by the absence of a clinically relevant animal model for evaluating their efficacy. This report describes the development and use of such a laboratory animal system. Selected concentrations of oxybenzone (2-hydroxy-4-methoxybenzophenone) in vehicle (0.1% to 6%) or vehicle alone were applied to the depilated dorsal skin of 30 Hartley strain female albino guinea pigs. The skin was irradiated with solar simulated UVA from a xenon light source. Acute radiation-induced damage was assayed by erythema grading and inhibition of [ 3 H]thymidine incorporation into epidermal DNA. Data from erythema grading studies indicated that a significant degree of photoprotection was achieved with 6%, 3%, and 1% solutions of benzophenone compared with the control vehicle; the 6% solution was significantly more photoprotective than the 3% and 1% solutions. A 6% solution afforded significant photoprotection when assayed by [ 3 H]thymidine incorporation

Radiation exposure of airplane crews. Exposure levels

International Nuclear Information System (INIS)

Bergau, L.

1995-01-01

Even at normal height levels of modern jet airplanes, the flying crew is exposed to a radiation level which is higher by several factors than the terrestrial radiation. There are several ways in which this can be hazardous; the most important of these is the induction of malignant growths, i.e. tumours. (orig./MG) [de

Radiation doses to the staff of a nuclear cardiology department

International Nuclear Information System (INIS)

Tsapaki, V.; Koutelou, M.; Theodorakos, A.; Kouzoumi, A.; Kitziri, S.; Tsiblouli, S.; Vardalaki, E.; Kyrozi, E.; Kouttou, S.

2002-01-01

The last years, new radiopharmaceuticals are used in a Nuclear Medicine (NM) Department. Nowadays, Single Photon Emission Computed Tomography (SPECT) is a method of routine imaging, a fact that has required increased levels of radioactivity in certain patient examinations. The staff that is more likely to receive the greatest radiation dose in a NM Department is the technologist who deals with performance of patient examination and injection of radioactive material and the nurse who is caring for the patients visiting the Department some of which being totally helpless. The fact that each NM Dept possesses equipment with certain specifications, deals with various kind of patients, has specific design and radiation protection measures which can differ from other NM Depts and uses various examination protocols, makes essential the need to investigate the radiation doses received by each member of the staff, so as to continuously monitor doses and take protective measures if required, control less experienced staff and ensure that radiation dose levels are kept as low as possible at all times. The purpose of the current study was to evaluate radiation dose to the nuclear cardiology department staff by thermoluminescent dosemeters (TLDs) placed on the the skin at thyroid and abdominal region as well as evaluating protection measures taken currently in the Dept

Radiation doses and possible radiation effects of low-level, chronic radiation in vegetation

International Nuclear Information System (INIS)

Rhoads, W.A.; Franks, L.A.

1975-01-01

Measurements were made of radiation doses in soil and vegetation in Pu-contaminated areas at the Nevada Test Site with the objective of investigating low-level, low-energy gamma radiation (with some beta radiation) effects at the cytological or morphological level in native shrubs. In this preliminary investigation, the exposure doses to shrubs at the approximate height of stem apical meristems were estimated from 35 to 140 R for a ten-year period. The gamma exposure dose estimated for the same period was 20.7 percent +- 6.4 percent of that recorded by the dosimeters used in several kinds of field instrument surveys. Hence, a survey instrument reading made at about 25 cm in the tops of shrubs should indicate about 1 / 5 the dosimeter-measured exposures. No cytology has yet been undertaken because of the drought since last winter. (auth)

Chromosome Aberration on High Level Background Natural Radiation Areas

International Nuclear Information System (INIS)

Yanti-Lusiyanti; Zubaidah-Alatas

2001-01-01

When the body is irradiated, all cells can suffer cytogenetic damage that can be seen as structural damage of chromosome in the lymphocytes. People no matter where they live in world are exposed to background radiation from natural sources both internal and external such as cosmic radiation, terrestrial radiation, cosmogenic radiation radon and thoron. Level of area natural ionizing radiation is varies depending on the altitude, the soil or rock conditions, particular food chains and the building materials and construction features. Level of normal areas of background exposure is annual effective dose 2.4 mSv and the high level areas of background exposure 20 mSv. This paper discuses the frequency of aberration chromosome especially dysenteries in several countries having high level radiation background. It seems that frequency of chromosome aberrations increase, generally with the increase of age of the people and the accumulated dose received. (author)

Lethal effect of short-wave (254 nm) UV-radiation on cells of Chlamidomonas reinhardii strains with different carotenoid content

International Nuclear Information System (INIS)

Kamchatova, I.E.; Chunaev, A.S.; Bronnikov, V.A.

1987-01-01

In experiments on related Chlamidomonas reinhardii strains of similar mating type a study was made of sensitivity of cells with different carotenoid content to UV-radiation of 254 nm. Mutants having a lower, as opposed to the wild type strain, content of carotenoids exhibited an increased radiosensitivity. A carotenoid-free mutant was found to possess a higher sensitivity to UV-radiation which was typical of the strain with the impaired excision repair system. The studied subclone of the UV-radiosensitive strain CC-888 was unable to photoreactivate the UV-induced damages which was typical of the wild-type strain. The content of carotenoids in cells of this subnuclone exceeded that in cells of mutants with the reduced pigmentation

Fabrication of biosynthetic vascular prostheses by 193-nm excimer laser radiation

Science.gov (United States)

Husinsky, Wolfgang; Csek, Ch.; Bartel, A.; Grabenwoeger, M.; Fitzal, F.; Wolner, Ernst

1998-05-01

This study was undertaken to investigate the feasibility of transmural capillary ingrowth into the inner surface of biosynthetic vascular prostheses (OmniflowTM) through perforations created by an excimer-laser, thus inducing an endothelial cell coverage. The biosynthetic vascular prostheses (10 cm length, 6 mm (phi) ) were perforated with an excimer laser ((phi) of the holes 50 - 100 micrometer, distance 4 mm) and implanted into the carotid arteries of 8 sheep. The laser tissue interaction process of 193 nm radiation ensures minimal thermal damage to the prostheses. They were compared to untreated OmniflowTM prostheses implanted at the contralateral side. Three months after implantation the prostheses were explanted and evaluated by gross morphology, histological examination and scanning electron microscopy. Scanning electron microscopy showed endothelial cells in the midgraft portion of all perforated prostheses, whereas collagen fibers, fibrin meshwork and activated platelets formed the inner layer in 6 out of 8 untreated OmniflowTM prostheses. It can be concluded, that spontaneous endothelialization of biosynthetic vascular prostheses can be achieved by transmural capillary ingrowth through perforations in the wall of the prostheses in an experimental sheep model.

Health effects of low level radiation

International Nuclear Information System (INIS)

Hattori, Sadao

1998-01-01

In 1982, Prof. Thomas Don Luckey of Missouri Univ. asserted 'Radiation Hormesis' on the Journal of Health Physics and he published two books. CRIEPI initiated the research program on Radiation Hormesis following his assertion to confirm 'is it true or not?' After nearly ten year research activities on data surveys and animal tests with many Universities, we are realizing scientific truth of bio-positive effects by low level radiation exposures. The interesting bio-positive effects we found could be categorized in following five groups. 1) Rejuvenation of cells such as increase of SOD and cell membrane permeability, 2) Moderation of psychological stress through response of key enzymes, 3) Suppression and therapy of adult-diseases such as diabetes and hypertension, 4) Suppression of cancer through enhancement of immune systems such as lymphocytes, 5) Suppression of cancer and ratio-adaptive response by activation of DNA repair and apoptosis. In the responses of many specialists to our initiation of radiation hormesis research program following T.D. Luckey's claim about low level radiation, I have to pick up for the first, the great success of Prof. Sakamoto. Prof. Sakamoto had been already applying whole body low dose irradiation for ten years before our radiation hormesis research started on the therapy to suppress the cancer reappearing after treatment. He reported about his successful trial to real patients and showed an enhancement of immune system. (author)

Health effects of low level radiation

Energy Technology Data Exchange (ETDEWEB)

Hattori, Sadao [Central Research Inst. of Electric Power Industry, Tokyo (Japan)

1998-12-31

In 1982, Prof. Thomas Don Luckey of Missouri Univ. asserted `Radiation Hormesis` on the Journal of Health Physics and he published two books. CRIEPI initiated the research program on Radiation Hormesis following his assertion to confirm `is it true or not?` After nearly ten year research activities on data surveys and animal tests with many Universities, we are realizing scientific truth of bio-positive effects by low level radiation exposures. The interesting bio-positive effects we found could be categorized in following five groups. 1) Rejuvenation of cells such as increase of SOD and cell membrane permeability, 2) Moderation of psychological stress through response of key enzymes, 3) Suppression and therapy of adult-diseases such as diabetes and hypertension, 4) Suppression of cancer through enhancement of immune systems such as lymphocytes, 5) Suppression of cancer and ratio-adaptive response by activation of DNA repair and apoptosis. In the responses of many specialists to our initiation of radiation hormesis research program following T.D. Luckey`s claim about low level radiation, I have to pick up for the first, the great success of Prof. Sakamoto. Prof. Sakamoto had been already applying whole body low dose irradiation for ten years before our radiation hormesis research started on the therapy to suppress the cancer reappearing after treatment. He reported about his successful trial to real patients and showed an enhancement of immune system. (author)

Sunlight suppressing rejection of 280- to 320-nm UV-radiation-induced skin tumors in mice

International Nuclear Information System (INIS)

Morison, W.L.; Kelley, S.P.

1985-01-01

Repeated exposure of female C3H/HeNCR- mice to sunlight prevented the normal immunologic rejection of a UV-induced tumor. This systemic immunologic alteration was transferred to syngeneic lethally X-irradiated animals with lymphoid cells from mice exposed to sunlight. The lymphoid cells also were able to suppress the capacity of lymphoid cells from normal animals to reject a UV-induced tumor. The 295- to 320-nm wave band appeared to be responsible for this immunosuppressive effect of sunlight because suppression was prevented by filtration of the radiation through Mylar and by application of a sunscreen containing para-aminobenzoic acid. These observations may have importance in understanding the pathogenesis of sunlight-induced skin cancer in humans

Overview of the hazards of low-level exposure to radiation

International Nuclear Information System (INIS)

Ritenour, E.R.

1984-01-01

In this chapter the authors are concerned with low-level radiation, doses of ionizing radiations that are ten to thousands of times smaller than those required to contract ARS. Low-level radiation may be defined as an absorbed dose of 10 rem or less delivered over a short period of time. A larger dose delivered over a long period of time, for instance, 50 rem in 10 years, may also be considered low level. The definition is purposely loose so as to cover a wide variety of sources of radiation exposure, such as natural background (100 mrem/year) occupational exposures (<5 rem/year), and medical applications, such as diagnostic radiography (<1 rem). Low-level radiation exposure does not produce ARS. The health effects that may be of concern in regard to low-level radiation are its long-term sequelae. Studies of survivors of high-level radiation exposure (both human and laboratory animals) have indicated that there are three health effects that should be examined at low levels of exposure: induction of cancer, birth abnormalities (from irradiation in utero), and genetic effects. No other long-term effects of low-level exposure have been conclusively demonstrated in animals or humans

Diode-pumped cw Nd:YAG three-level laser at 869 nm.

Science.gov (United States)

Lü, Yanfei; Xia, Jing; Cheng, Weibo; Chen, Jifeng; Ning, Guobin; Liang, Zuoliang

2010-11-01

We report for the first time (to our knowledge) a diode-pumped Nd:YAG laser emitting at 869 nm based on the (4)F(3/2)-(4)I(9/2) transition, generally used for a 946 nm emission. Power of 453 mW at 869 nm has been achieved in cw operation with a fiber-coupled laser diode emitting 35.4 W at 809 nm. Intracavity second-harmonic generation in the cw mode has also been demonstrated with power of 118 mW at 435 nm by using a BiB(3)O(6) nonlinear crystal. In our experiment, we used a LiNbO(3) crystal lens to complement the thermal lens of the laser rod, and we obtained good beam quality and high output power stability.

Low-level radiation risks in people

International Nuclear Information System (INIS)

Goloman, M.; Filjushkin, V. lgor

1993-01-01

Using the limited human data plus the relationships derived from the laboratory, a leukemia risk model has been developed as well as a suggested model for other cancers in people exposed to low levels of radiation. Theoretical experimental and epidemiological evidence will be presented in an integrated stochastic model for projection of radiation-induced cancer risks

Fused Silica Final Optics for Inertial Fusion Energy: Radiation Studies and System-Level Analysis

International Nuclear Information System (INIS)

Latkowski, Jeffery F.; Kubota, Alison; Caturla, Maria J.; Dixit, Sham N.; Speth, Joel A.; Payne, Stephen A.

2003-01-01

The survivability of the final optic, which must sit in the line of sight of high-energy neutrons and gamma rays, is a key issue for any laser-driven inertial fusion energy (IFE) concept. Previous work has concentrated on the use of reflective optics. Here, we introduce and analyze the use of a transmissive final optic for the IFE application. Our experimental work has been conducted at a range of doses and dose rates, including those comparable to the conditions at the IFE final optic. The experimental work, in conjunction with detailed analysis, suggests that a thin, fused silica Fresnel lens may be an attractive option when used at a wavelength of 351 nm. Our measurements and molecular dynamics simulations provide convincing evidence that the radiation damage, which leads to optical absorption, not only saturates but that a 'radiation annealing' effect is observed. A system-level description is provided, including Fresnel lens and phase plate designs

Low-level radiation waste management system

International Nuclear Information System (INIS)

Kubofcik, K.W.

1990-01-01

This patent describes a low-level radiation waste container set for use in conjunction with an open-topped receptacle. It comprises: a receptacle liner having a closed end and an open end, the receptacle liner sized for deployment as an inserted liner in an open-topped receptacle for collecting low-level radiation waste material within the receptacle liner within the open-topped receptacle; a cover sized and shaped to fit over the open top of the open-topped receptacle and the receptacle liner therein with the cover is in a closed position. The cover having a depending skirt which, when the cover is in the closed position, extends downwardly to overlap the open-topped receptacle adjacent the open top thereof and a portion of the receptacle liner received therein; and the receptacle liner and cover being fabricated of flexible radiation shielding material

Photosensitivity mechanism of undoped poly(methyl methacrylate) under UV radiation at 325 nm and its spatial resolution limit

DEFF Research Database (Denmark)

Sáez-Rodríguez, D.; Nielsen, Kristian; Bang, Ole

2014-01-01

that increasing strain during photo-inscription leads to an increased photosensitivity, which is evidence of photodegradation. Likewise, refractive index change in the fiber was measured to be positive, which provides evidence for further polymerization of the material. Finally, we relate the data obtained......In this Letter, we provide evidence suggesting that the main photosensitive mechanism of an undoped poly(methyl methacrylate)-based microstructured optical fiber under UV radiation at 325 nm is a competitive process of both photodegradation and polymerization. We found experimentally...

Low-level radiation: biological interactions, risks, and benefits. A bibliography

International Nuclear Information System (INIS)

1978-09-01

The bibliography contains 3294 references that were selected from the Department of Energy's data base (EDB). The subjects covered are lower-level radiation effects on man, environmental radiation, and other biological interactions of radiation that appear to be applicable to the low-level radiation problem

Effect of ionizing radiation on in situ Raman scattering and photoluminescence of silica optical fibers

International Nuclear Information System (INIS)

Bilodeau, T.G.; Ewing, K.J.; Nau, G.M.; Aggarwal, I.D.

1995-01-01

Raman fiber optic chemical sensors provide remote situ characterization capability. One application of Raman fiber optic chemical sensors is the characterization of the contents of nuclear waste tanks. In these tanks it is expected that approximately 20 meters of optical fiber will be exposed to radiation levels between 100 and 1,000 rads/hour. In support of this work two silica optical fiber types (one a communications grade fiber and the other nominally radiation resistant) have been tested at the radiation levels expected in the tanks. Luminescence and Raman scattering measurements have been performed in situ with 488-nm excitation on two types of silica optical fiber exposed to a constant low to moderate dose rate of gamma radiation of 880 rads(Si)/hour from a 60 Co source for a total dose of greater than 45 krads. The nominally radiation-resistant fiber was also excited with 514.5-nm and near-infrared 830-nm laser radiation. The rate of the silica Raman signal decrease is more than three times greater for the visible excitation wavelengths than for the 830-nm excitation for the radiation resistant fiber. The behavior of the 650-nm photoluminescence line upon irradiation was different for the two fibers studied, both in terms of the shift of the 650-nm line and rate of increase of the normalized photoluminescence intensity. In all cases the photoluminescence from the fibers was less than the Raman intensity. No radioluminescence was observed in either fiber. The radiation resistant fiber exhibited photo bleaching effects on the Raman transmission when photoannealed with 488-nm laser light

Effect of ionizing radiation on in situ Raman scattering and photoluminescence of silica optical fibers

Science.gov (United States)

Bilodeau, T. G.; Ewing, K. J.; Nau, G. M.; Aggarwai, I. D.

1995-02-01

Raman fiber optic chemical sensors provide remote in situ characterization capability. One application of Raman fiber optic chemical sensors is the characterization of the contents of nuclear waste tanks. In these tanks it is expected that approximately 20 meters of optical fiber will be exposed to radiation levels between 100 and 1000 rads/hour. In support of this work two silica optical fiber types (one a communications grade fiber and the other nominally radiation resistant) have been tested at the radiation levels expected in the tanks. Luminescence and Raman scattering measurements have been performed in situ with 488-nm excitation on two types of silica optical fiber exposed to a constant low to moderate dose rate of gamma radiation of 880 rads(Si)/hour from a /sup 60/Co source for a total dose of greater than 45 krads. The nominally radiation-resistant fiber was also excited with 514.5-nm and near-infrared 830-nm laser radiation. The rate of the silica Raman signal decrease is more than three times greater for the visible excitation wavelengths than for the 830-nm excitation for the radiation resistant fiber. The behavior of the 650-nm photoluminescence line upon irradiation was different for the two fibers studied, both in terms of the shift of the 650-nm line and rate of increase of the normalized photoluminescence intensity. In all cases the photoluminescence from the fibers was less than the Raman intensity. No radioluminescence was observed in either fiber. The radiation resistant fiber exhibited photobleaching effects on the Raman transmission when photoannealed with 488-nm laser light.

308nm Excimer Laser in Dermatology

Science.gov (United States)

Mehraban, Shadi

2014-01-01

308nm xenon-chloride excimer laser, a novel mode of phototherapy, is an ultraviolet B radiation system consisting of a noble gas and halide. The aim of this systematic review was to investigate the literature and summarize all the experiments, clinical trials and case reports on 308-nm excimer laser in dermatological disorders. 308-nm excimer laser has currently a verified efficacy in treating skin conditions such as vitiligo, psoriasis, atopic dermatitis, alopecia areata, allergic rhinitis, folliculitis, granuloma annulare, lichen planus, mycosis fungoides, palmoplantar pustulosis, pityriasis alba, CD30+ lympho proliferative disorder, leukoderma, prurigo nodularis, localized scleroderma and genital lichen sclerosus. Although the 308-nm excimer laser appears to act as a promising treatment modality in dermatology, further large-scale studies should be undertaken in order to fully affirm its safety profile considering the potential risk, however minimal, of malignancy, it may impose. PMID:25606333

Mathematical simulation of the amplification of 1790-nm laser radiation in a nuclear-excited He - Ar plasma containing nanoclusters of uranium compounds

Science.gov (United States)

Kosarev, V. A.; Kuznetsova, E. E.

2014-02-01

The possibility of applying dusty active media in nuclearpumped lasers has been considered. The amplification of 1790-nm radiation in a nuclear-excited dusty He - Ar plasma is studied by mathematical simulation. The influence of nanoclusters on the component composition of the medium and the kinetics of the processes occurring in it is analysed using a specially developed kinetic model, including 72 components and more than 400 reactions. An analysis of the results indicates that amplification can in principle be implemented in an active laser He - Ar medium containing 10-nm nanoclusters of metallic uranium and uranium dioxide.

Low-level radiation: biological interactions, risks, and benefits. A bibliography

Energy Technology Data Exchange (ETDEWEB)

None

1978-09-01

The bibliography contains 3294 references that were selected from the Department of Energy's data base (EDB). The subjects covered are lower-level radiation effects on man, environmental radiation, and other biological interactions of radiation that appear to be applicable to the low-level radiation problem.

Differential response of radish plants to supplemental ultraviolet-B radiation under varying NPK levels: chlorophyll fluorescence, gas exchange and antioxidants.

Science.gov (United States)

Singh, Suruchi; Kumari, Rima; Agrawal, Madhoolika; Agrawal, Shashi Bhushan

2012-07-01

Current and projected increases in ultraviolet-B (UV-B; 280-315 nm) radiation may alter crop growth and yield by modifying the physiological and biochemical functions. This study was conducted to assess the possibility of alleviating the negative effects of supplemental UV-B (sUV-B; 7.2 kJ m⁻² day⁻¹; 280-315 nm) on radish (Raphanus sativus var Pusa Himani) by modifying soil nitrogen (N), phosphorus (P) and potassium (K) levels. The N, P and K treatments were recommended dose of N, P and K, 1.5 times recommended dose of N, P and K, 1.5 times recommended dose of N and 1.5 times recommended dose of K. Plants showed variations in their response to UV-B radiation under varying soil NPK levels. The minimum damaging effects of sUV-B on photosynthesis rate and stomatal conductance coupled with minimum reduction in chlorophyll content were recorded for plants grown at recommended dose of NPK. Flavonoids increased under sUV-B except in plants grown at 1.5 times recommended dose of N. Lipid peroxidation (LPO) also increased in response to sUV-B at all NPK levels with maximum at 1.5 times recommended dose of K and minimum at recommended dose of NPK. This study revealed that sUV-B radiation negatively affected the radish plants by reducing the photosynthetic efficiency and increasing LPO. The plants grown at 1.5 times recommended dose of NPK/N/K could not enhance antioxidative potential to the extent as recorded at recommended dose of NPK and hence showed more sensitivity to sUV-B. Copyright © Physiologia Plantarum 2012.

Evidence for Radiative Recombination of O+ Ions as a Significant Source of O 844.6 nm Emission Excitation

Science.gov (United States)

Waldrop, L.; Kerr, R. B.; Huang, Y.

2018-04-01

Photoelectron (PE) impact on ground-state O(3P) atoms is well known as a major source of twilight 844.6 nm emission in the midlatitude thermosphere. Knowledge of the PE flux can be used to infer thermospheric oxygen density, [O], from photometric measurements of 844.6 nm airglow, provided that PE impact is the dominant process generating the observed emission. During several spring observational campaigns at Arecibo Observatory, however, we have observed significant 844.6 nm emission throughout the night, which is unlikely to arise from PE impact excitation which requires solar illumination of either the local or geomagnetically conjugate thermosphere. Here we show that radiative recombination (RR) of O+ ions is likely responsible for the observed nighttime emission, based on model predictions of electron and O+ ion density and temperature by the Incoherent Scatter Radar Ionosphere Model. The calculated emission brightness produced by O + RR exhibits good agreement with the airglow data, in that both decay approximately monotonically throughout the night at similar rates. We conclude that the conventional assumption of a pure PE impact source is most likely to be invalid during dusk twilight, when RR-generated emission is most significant. Estimation of [O] from measurements of 844.6 nm emission demands isolation of the PE impact source via coincident estimation of the RR source, and the effective cross section for RR-generated emission is found here to be consistent with optically thin conditions.

Low-level radiation: The cancer controversy

International Nuclear Information System (INIS)

Stewart, A.M.

1990-01-01

According to early studies it would be safe to assume there are no late effects of radiation apart from cancer, no lasting selective effects of the early deaths of A-bomb victims, and no cancer risk at low dose levels (below 20 rad). The nuclear establishment had good reason to believe that a potentially dangerous situation had been completely defused, and optimists were still free to regard daily exposure to background radiation as a benign influence. For several years the only indication to the contrary was the Oxford survey's finding on prenatal X-rays. But today we face the possibility that there are other late effects of radiation besides cancer; and the possibility that the selection effects of the two nuclear explosions are still reflected in death rates among survivors and are the reason why no cancer effects have been found at low dose levels. If these possibilities are confirmed, we may one day realize how fortunate it was that the Oxford survey findings put a brake on the enthusiasms of nuclear power advocates. Otherwise, we might never have pressed for direct studies of the effects of low doses of radiation. 7 refs

PILOT STUDY: Report on the CCPR Pilot Comparison: Spectral Responsivity 10 nm to 20 nm

Science.gov (United States)

Scholze, Frank; Vest, Robert; Saito, Terubumi

2010-01-01

The CCPR Pilot Comparison on spectral responsivity in the 10 nm to 20 nm spectral range was carried out within the framework of the CIPM Mutual Recognition Arrangement by three laboratories: PTB (Germany), NIST (USA), and NMIJ/AIST (Japan) with PTB acting as the central and reporting laboratory. All participating laboratories used monochromatized synchrotron radiation. PTB and NIST used a cryogenic radiometer as the primary standard detector and NMIJ, an ionization chamber with extrapolation by a wavelength-independent detector. The aim of the pilot comparison was to check the accuracy of the radiometric scale of spectral responsivity in the short wavelength EUV spectral range which has recently gained in technological importance. The wavelengths of measurement were from 11.5 nm to 20 nm in 0.5 nm steps and additionally 12.2 nm. The comparison was carried out through the calibration of a group of transfer standard detectors. Two sets of three diodes of types AXUV and SXUV from International Radiation Detectors, Inc. were used for the comparison. The comparison had the form of a star comparison: Pilot-lab A-pilot-lab B-pilot, PTB acting as the pilot laboratory. All results were communicated directly to the pilot laboratory. The report describes in detail the measurements made at PTB and summarizes the reports submitted by the participants. Measurements carried out by the pilot laboratory before and after the circulation of the detectors proved that the stability of the detectors was sufficient for the comparison. For the type AXUV detectors, however, changes in their responsivity contributed to the uncertainty of the comparison. Measurement results from participants and their associated uncertainties were analyzed in this report according to the Guidelines for CCPR Comparison Report Preparation. The uncertainty contributions were separated, as to whether they are wavelength dependent or not. All bilateral DoE are well within the respective k = 2 expanded uncertainty

Radiobiologic effects at low radiation levels

International Nuclear Information System (INIS)

Casarett, G.W.

1975-01-01

Data are reviewed on the effects of low radiation doses on mammals. Data from the 1972 report on the Biological Effects of Ionizing Radiation issued by the Advisory Committee of the National Academy of Sciences and National Research Council are discussed. It was concluded that there are certain radiosensitive systems in which low doses of radiation may cause degenerative effects, including gametogenic epithelium, lens of the eye, and developing embryos. Despite extensive investigation of genetic effects, including chromosomal effects, neither the amount of change that will be caused by very low levels of irradiation nor the degree of associated detriment is known

Absorption of ultraviolet radiation by antarctic phytoplankton

Energy Technology Data Exchange (ETDEWEB)

Vernet, M.; Mitchell, B.G. (Univ. of California-San Diego, La Jolla (United States))

1990-01-09

Antarctic phytoplankton contain UV-absorbing compounds that may block damaging radiation. Compounds that absorb from 320-340 nm were observed in spectral absorption of both particulates and in methanol extracts of the particulates. The decrease in the total concentration of these UV compounds with respect to chlorophyll a, as measured by the ratio of in vitro absorption at 335 nm to absorption at 665 nm is variable and decreases with depth. We observed up to 5-fold decrease in this ratio for samples within the physically mixes surface layer. The absorption of UV radiation in methanol extracts, which peaks from 320 to 340 nm, may be composed of several compounds. Shifts in peak absorption with depth (for example, from 331 nm at surface to 321 nm at 75 m), may be interpreted as a change in composition. Ratios of protective yellow xanthophylls (diadinoxanthin + diatoxanthin) to photosynthetic fucoxanthin-like pigments have highest values in surface waters. As these pigments also absorb in the near UV, their function might extend to protection as well as utilization of UV radiation for photosynthesis. We document strong absorption in the UV from 320-330 nm for Antarctic marine particulates. Below this region of the solar energy spectrum, absolute energy levels of incident radiation drop off dramatically. Only wavelengths shorter than about 320 nm will be significantly enhanced due to ozone depletion. If the absorption we observed serves a protective role for phytoplankton photosynthesis, it appears the peak band is in the region where solar energy increases rapidly, and not in the region where depletion would cause significant variations in absolute flux.

DNA damage in cultured human skin fibroblasts exposed to excimer laser radiation

Energy Technology Data Exchange (ETDEWEB)

Rimoldi, D.; Miller, A.C.; Freeman, S.E.; Samid, D. (Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD (USA))

1991-06-01

Ultraviolet excimer lasers are being considered for use in a variety of refractive and therapeutic procedures, the long-term biologic consequences of which are unknown. The effect of sublethal doses of 193-nm laser radiation on cellular DNA was examined in cultured human skin fibroblasts. In contrast to 248 nm, treatments with the 193-nm laser radiation below 70 J/m2 did not cause significant pyrimidine dimer formation in the skin cells. This was indicated by the lack of excision repair activities (unscheduled DNA synthesis assay), and further demonstrated by direct analysis of pyrimidine dimers in DNA from irradiated cells. However, a low level of unscheduled DNA synthesis could be detected following irradiation at 193 nm with 70 J/m2. Both the 193-nm and 248-nm radiation were able to induce chromosomal aberrations, as indicated by a micronucleus assay. A dose-dependent increase in micronuclei frequency was observed 48 and 72 h after laser irradiation. These results indicate that exposure of actively replicating human skin fibroblasts to sublethal doses of either 193- or 248-nm laser radiation can result in genotoxicity.

Acceptable level of radiation risk and its perception

International Nuclear Information System (INIS)

Kusama, Tomoko; Shinozaki, Motoshi; Yoshizawa, Yasuo

1987-01-01

The acceptable level of radiation risk for public members, that is 10 -5 /y, was proposed by ICRP and other international organizations. We studied to survey basic procedures of deriving this value and to derive an acceptable risk value in Japan by using similar procedures. The basic procedures to derive 10 -5 /y were found as follows; (1) 0.1 percent of annual mortality from all diseases, (2) 0.1 percent of life time risk, (3) one percent of mortality from all causes in each age cohort and (4) corresponding value to 1 mSv annual radiation exposure. From these bases we derived the value of 10 -5 /y as acceptable risk level in Japan. The perception to risk level of 10 -5 /y in conventional life was investigated by means of questionnaires for 1,095 college students living in Tokyo. The risks considered in this study were natural background radiation, coffee, skiing, X-ray diagnosis, spontaneous cancer, passive smoking and air pollution. The most acceptable risk was the risk related with natural background radiation. And the risk of natural background radiation was more easily accepted by the students who had knowledges on natural background radiation. On the other hand, the risk from air pollution or passive smoking was the most adverse one. (author)

The action of NIR (808nm) laser radiation and gold nanorods labeled with IgA and IgG human antibodies on methicillin-resistant and methicillin sensitive strains of Staphylococcus aureus

Science.gov (United States)

Tuchina, Elena S.; Petrov, Pavel O.; Ratto, Fulvio; Centi, Sonia; Pini, Roberto; Tuchin, Valery V.

2015-03-01

The effect of NIR laser radiation (808 nm) on methicillin-sensitive and methicillin resistant strains of Staphylococcus aureus incubated with gold nanorods is studied. Nanorods having length of 44 (± 4) nm and diameter of 10 (± 3) nm with the absorption maximum in the NIR (800 nm), functionalized with human immunoglobulins IgA and IgG, were synthesized and used in the studies. The killing ability up to 97% of the microorganism populations by using this nanotechnology was shown.

Effects of high vs low-level radiation exposure

International Nuclear Information System (INIS)

Bond, V.P.

1983-01-01

In order to appreciate adequately the various possible effects of radiation, particularly from high-level vs low-level radiation exposure (HLRE, vs LLRE), it is necessary to understand the substantial differences between (a) exposure as used in exposure-incidence curves, which are always initially linear and without threshold, and (b) dose as used in dose-response curves, which always have a threshold, above which the function is curvilinear with increasing slope. The differences are discussed first in terms of generally familiar nonradiation situations involving dose vs exposure, and then specifically in terms of exposure to radiation, vs a dose of radiation. Examples are given of relevant biomedical findings illustrating that, while dose can be used with HLRE, it is inappropriate and misleading the LLRE where exposure is the conceptually correct measure of the amount of radiation involved

High-efficiency generation of pulsed Lyman-α radiation by resonant laser wave mixing in low pressure Kr-Ar mixture.

Science.gov (United States)

Saito, Norihito; Oishi, Yu; Miyazaki, Koji; Okamura, Kotaro; Nakamura, Jumpei; Louchev, Oleg A; Iwasaki, Masahiko; Wada, Satoshi

2016-04-04

We report an experimental generation of ns pulsed 121.568 nm Lyman-α radiation by the resonant nonlinear four-wave mixing of 212.556 nm and 845.015 nm radiation pulses providing a high conversion efficiency 1.7x10-3 with the output pulse energy 3.6 μJ achieved using a low pressure Kr-Ar mixture. Theoretical analysis shows that this efficiency is achieved due to the advantage of using (i) the high input laser intensities in combination with (ii) the low gas pressure allowing us to avoid the onset of full-scale discharge in the laser focus. In particular, under our experimental conditions the main mechanism of photoionization caused by the resonant 2-photon 212.556 nm radiation excitation of Kr atoms followed by the 1-photon ionization leads to ≈17% loss of Kr atoms and efficiency loss only by the end of the pulse. The energy of free electrons, generated by 212.556 nm radiation via (2 + 1)-photon ionization and accelerated mainly by 845.015 nm radiation, remains during the pulse below the level sufficient for the onset of full-scale discharge by the electron avalanche. Our analysis also suggests that ≈30-fold increase of 845.015 nm pulse energy can allow one to scale up the L-α radiation pulse energy towards the level of ≈100 μJ.

Assessment of dose level of ionizing radiation in army scrap

International Nuclear Information System (INIS)

Abdel Hamid, S. M.

2010-12-01

Radiation protection is the science of protecting people and the environment from the harmful effects of ionizing radiation, which includes both particle radiation and high energy radiation. Ionizing radiation is widely used in industry and medicine. Any human activity of nuclear technologies should be linked to the foundation of scientific methodology and baseline radiation culture to avoid risk of radiation and should be working with radioactive materials and expertise to understand, control practices in order to avoid risks that could cause harm to human and environment. The study was conducted in warehouses and building of Sudan air force Khartoum basic air force during September 2010. The goal of this study to estimate the radiation dose and measurement of radioactive contamination of aircraft scrap equipment and increase the culture of radiological safety as well as the concept of radiation protection. The results showed that there is no pollution observed in the contents of the aircraft and the spire part stores outside, levels of radiation dose for the all contents of the aircraft and spire part within the excitable level, except temperature sensors estimated radiation dose about 43 μSv/h outside of the shielding and 12 μSv/h inside the shielding that exceeded the internationally recommended dose level. One of the most important of the identification of eighteen (18) radiation sources used in temperature and fuel level sensors. These are separated from the scrap, collected and stored in safe place. (Author)

Low-level radiation effects: a fact book

International Nuclear Information System (INIS)

Brill, A.B.; Adelstein, S.J.; Saenger, E.L.; Webster, E.W.

1982-01-01

Low Level Raidation Effects: A Fact Book, prepared by the Society of Nuclear Medicine Subcommittee on the Risks of Low-Level Ionizing Radiation, attempts to examine the health effects of small doses of radiation. For immediate questions, this work provides a well-organized brief summary of recent radiologic data from refereed scientific literature and from the publications of advisory groups such as the National Council of Radiation Protection and Measurement (NCRP), the International Commission on Radiological Protection (ICRP), the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR), and the National Academy of Sciences (NAS). Since it consists almost entirely of tables and graphs from the above-mentioned sources along with summary paragraphs, the Fact Book is very useful in the preparation of lectures. The book is divided into seven sections. Chapter One, Glossary, Units and Conversion Factors, is useful because nearly all data given in the rest of the book is in conventional units and should be converted to SI units for future technical audiences. Chapter 2, Radiobiology, covers the fundamental principles of the field. Chapter 3, Radiation Doses, can be used to help an audience appreciate the relative magnitudes of radiation exposures they may read about or encounter. Chapter 4, Late Somatic Effects of Low Doses of Ionizing Radiation, gives data concerning cancer induction and embryonic effects, and Chapter 5 provides data on genetic effects Chapter 6, Risks, Statistical Facts and Public Perception can be used to compare the risks of radiation exposure with more commonly encountered risks

Ultraviolet radiation and the snow alga Chlamydomonas nivalis (Bauer) Wille.

Science.gov (United States)

Gorton, Holly L; Vogelmann, Thomas C

2003-06-01

Aplanospores of Chlamydomonas nivalis are frequently found in high-altitude, persistent snowfields where they are photosynthetically active despite cold temperatures and high levels of visible and ultraviolet (UV) radiation. The goals of this work were to characterize the UV environment of the cells in the snow and to investigate the existence and localization of screening compounds that might prevent UV damage. UV irradiance decreased precipitously in snow, with UV radiation of wavelengths 280-315 nm and UV radiation of wavelengths 315-400 nm dropping to 50% of incident levels in the top 1 and 2 cm, respectively. Isolated cell walls exhibited UV absorbance, possibly by sporopollenin, but this absorbance was weak in images of broken or plasmolyzed cells observed through a UV microscope. The cells also contained UV-absorbing cytoplasmic compounds, with the extrachloroplastic carotenoid astaxanthin providing most of the screening. Additional screening compound(s) soluble in aqueous methanol with an absorption maximum at 335 nm played a minor role. Thus, cells are protected against potentially high levels of UV radiation by the snow itself when they live several centimeters beneath the surface, and they rely on cellular screening compounds, chiefly astaxanthin, when located near the surface where UV fluxes are high.

Multiple chromosome aberrations among newborns from high level natural radiation area and normal level natural radiation area of south west coast of Kerala

International Nuclear Information System (INIS)

Soren, D.C.; Ramachandran, E.N.; Karuppasamy, C.V.; Cheriyan, V.D.; Anil Kumar, V.; Koya, P.K.M.; Seshadri, M.

2010-01-01

Cord blood samples were collected in heparin vials and microculture techniques employed to obtain good metaphase chromosome spreads. In cytogenetic studies on newborns cells with multiple aberrations were recorded in 57 from a total of 27285 newborns (1266972 cells). Of these 17294 newborns (964140 cells) were from High Level Natural Radiation Area (HLNRA) and 9991 newborns (302832 cells) from Normal Level Natural Radiation Area (NLNRA). Cells with multiple aberrations were observed in 38 and 19 newborns from High and Normal Level Natural Radiation Area respectively. On an average one cell with multiple aberrations was observed among 479 newborns. Cells with multiple aberrations were observed in newborns from HLNRA as well as NLNRA in both males and females. Gender difference of newborns, maternal age group and background radiation levels did not seem to have any influence in the occurrence of Multiple chromosome aberrations

Regulatory control of low level radiation exposure in Tanzania

International Nuclear Information System (INIS)

Nyanda, A.M.; Muhogora, W.E.

1997-01-01

In Tanzania, the radiation protection law was issued in 1983. Under this law, the National Radiation Commission is responsible for safe uses of ionizing radiation. The regulatory control of the resulting doses from the uses of radiation sources in medicine, industry, research and teaching is presented. The system of control reflects the existing interactions between the National Radiation Commission and users through the established radiation protection infrastructure. From the national dose registry data, it is found that the highest annual individual doses over 10 years ago, came from less than 5% of total monitored workers and were in the range 10 - 15 mSv y -1 . The experienced radiation levels in uncontrolled areas of potential workplaces is less than 1 μSv h -1 . The possibility for associating such low dose levels to the effectiveness of the existing regulatory dose control framework is discussed. Despite of this achievement, the need to improve further the radiation protection and safety programs is found necessary. (author)

Intermediate bands versus levels in non-radiative recombination

International Nuclear Information System (INIS)

Luque, Antonio; Marti, Antonio; Antolin, Elisa; Tablero, Cesar

2006-01-01

There is a practical interest in developing semiconductors with levels situated within their band gap while preventing the non-radiative recombination that these levels promote. In this paper, the physical causes of this non-radiative recombination are analyzed and the increase in the density of the impurities responsible for the mid-gap levels to the point of forming bands is suggested as the means of suppressing the recombination. Simple models supporting this recommendation and helping in its quantification are presented

Acceptable level of radiation risk and its perception

Energy Technology Data Exchange (ETDEWEB)

Kusama, Tomoko; Shinozaki, Motoshi; Yoshizawa, Yasuo

1987-03-01

The acceptable level of radiation risk for public members, that is 10/sup -5//y, was proposed by ICRP and other international organizations. We studied to survey basic procedures of deriving this value and to derive an acceptable risk value in Japan by using similar procedures. The basic procedures to derive 10/sup -5//y were found as follows; (1) 0.1 percent of annual mortality from all diseases, (2) 0.1 percent of life time risk, (3) one percent of mortality from all causes in each age cohort and (4) corresponding value to 1 mSv annual radiation exposure. From these bases we derived the value of 10/sup -5//y as acceptable risk level in Japan. The perception to risk level of 10/sup -5//y in conventional life was investigated by means of questionnaires for 1,095 college students living in Tokyo. The risks considered in this study were natural background radiation, coffee, skiing, X-ray diagnosis, spontaneous cancer, passive smoking and air pollution. The most acceptable risk was the risk related with natural background radiation. And the risk of natural background radiation was more easily accepted by the students who had knowledges on natural background radiation. On the other hand, the risk from air pollution or passive smoking was the most adverse one.

Decay kinetics of Krsup(*) levels populated by ArF laser radiation

International Nuclear Information System (INIS)

Wren, D.J.; Setser, D.W.

1981-01-01

The Kr 6p [3/2] 2 (or 3p 6 ) level was pumped via a two-photon absorption using a focused ArF laser (193 nm). The time dependent fluorescence from excited Kr levels was observed using a monochromator and photomultiplier tube and transient digitizer. Fluorescence from the pumped level, observed via the 3p 6 → 1s 5 transition, has a lifetime of 8 +- 2 ns independent of the Kr pressure (2-30 Torr). Fluorescence from other levels of the Kr (4p 5 6p) manifold was either unobserved or weak. Strong fluorescence was observed from the Kr (4p 5 5p) levels via transitions to the Kr (4p 5 5s) levels, the highest populated levels being 2p 6 , 2p 8 and 2p 9 . All Kr (4p 5 5p) levels display effective lifetimes much longer than the radiative lifetimes; effective zero pressure lifetimes for Kr 2p 3 , 2p 6 and 2p 7 are 72 +- 15, 66 +- 15 and 90 +- 15 ns, respectively. The short lifetime of the Kr (3p 6 ) level is explained by very fast collisional depopulation by photoelectrons produced in three photon ionization of Kr by the ArF laser. The Kr (4p 5 5p) levels are populated indirectly from the Kr (3p 6 ) level and the long lifetimes of the Kr (4p 5 5p) levels represent the lifetime of the intermediate state (or states) which lead to the Kr (4p 5 5p) levels. Strong possibilities for the intermediate states are the Kr (4p 5 4d) levels. (orig.)

Background compensation for a radiation level monitor

Science.gov (United States)

Keefe, D.J.

1975-12-01

Background compensation in a device such as a hand and foot monitor is provided by digital means using a scaler. With no radiation level test initiated, a scaler is down-counted from zero according to the background measured. With a radiation level test initiated, the scaler is up-counted from the previous down-count position according to the radiation emitted from the monitored object and an alarm is generated if, with the scaler having crossed zero in the positive going direction, a particular number is exceeded in a specific time period after initiation of the test. If the test is initiated while the scale is down-counting, the background count from the previous down- count stored in a memory is used as the initial starting point for the up-count.

Building blocks for future detectors: Silicon test masses and 1550 nm laser light

International Nuclear Information System (INIS)

Schnabel, R; Britzger, M; Burmeister, O; Danzmann, K; Duck, J; Eberle, T; Friedrich, D; Luck, H; Mehmet, M; Steinlechner, S; Willke, B; Brueckner, F; Nawrodt, R

2010-01-01

Current interferometric gravitational wave detectors use the combination of quasi-monochromatic, continuous-wave laser light at 1064 nm and fused silica test masses at room temperature. Detectors of the third generation, such as the Einstein-Telescope, will involve a considerable sensitivity increase. The combination of 1550 nm laser radiation and crystalline silicon test masses at low temperatures might be important ingredients in order to achieve the sensitivity goal. Here we compare some properties of the fused silica and silicon test mass materials relevant for decreasing the thermal noise in future detectors as well as the recent technology achievements in the preparation of laser radiation at 1064 nm and 1550 nm relevant for decreasing the quantum noise. We conclude that silicon test masses and 1550 nm laser light have the potential to form the future building blocks of gravitational wave detection.

About the principles of radiation level normalization

International Nuclear Information System (INIS)

Nosovskij, A.V.

2000-01-01

The paper highlights the impact being made by the radiation level normalization principles upon the social and economic indicators. The newly introduced radiation safety standards - 97 are taken as an example. It is emphasized that it is necessary to use a sound approach while defining radiation protection standards, taking into consideration economic and social factors existing in Ukraine at the moment. Based on the concept of the natural radiation background and available results of the epidemiological surveys, the dose limits are proposed for the radiation protection standards. The paper gives a description of the dose limitation system recommended by the International Committee for Radiation Protection. The paper highlights a negative impact of the line non threshold concept, lack of special knowledge in the medical service and mass media to make decisions to protect people who suffered from the Chernobyl accident

Radiation transport in high-level waste form

International Nuclear Information System (INIS)

Arakali, V.S.; Barnes, S.M.

1992-01-01

The waste form selected for vitrifying high-level nuclear waste stored in underground tanks at West Valley, NY is borosilicate glass. The maximum radiation level at the surface of a canister filled with the high-level waste form is prescribed by repository design criteria for handling and disposition of the vitrified waste. This paper presents an evaluation of the radiation transport characteristics for the vitreous waste form expected to be produced at West Valley and the resulting neutron and gamma dose rates. The maximum gamma and neutron dose rates are estimated to be less than 7500 R/h and 10 mRem/h respectively at the surface of a West Valley canister filled with borosilicate waste glass

Epidemiological studies in high-background radiation areas its potential contribution to evaluating risk of low-level radiation

International Nuclear Information System (INIS)

Akiba, Suminori; Nair, R.K.; Nakamura, Seiichi; Mizuno, Shoich

2008-01-01

The health effect of low-level ionizing radiation is yet unclear. As pointed out by Upton in his review (Upton, 1989), low-level ionizing radiation seems to have different biological effects from what high-level radiation has. Its evaluation requires epidemiological studies of scale-large cohorts (ICRP 99, 2005) such of atomic bomb survivors and nuclear workers. Epidemiological studies in high-background radiation (HBR) areas are also expected to make a significant contribution toward this end. Among several HBR areas in the world, Yangjiang, Guangdong Province in China, Karunagappally in Kerala State of India, Manawalakurichi and Koodankulam in Tamil Nadu of India, and Ramsar in Iran are important areas where epidemiological studies are possible, because of their relatively high background radiation levels and large population sizes. (author)

Variation in well-head gamma radiation levels at the Nigerian ...

African Journals Online (AJOL)

It was generally observed that the level of radiation around the well heads is less than 20x 10-12mSv/hr, which is in agreement with the International Atomic Energy Agency\\'s standard on ionizing radiation background level. Keywords: Radiation, crude oil, radionuclide, contaminant, exposure. Nigerian Journal of Physics ...

Ionizing radiation: levels and effects. Volume I. Levels

International Nuclear Information System (INIS)

1972-01-01

This is the sixth substantive report of the United Nations Scientific Committee on the Effects of Atomic Radiation to the General Assembly. It reviews the levels of radiation received from all sources to which man is exposed and, among the effects of ionizing radiation, it considers the genetic effects, the effects on the immune response and the induction of malignancies in animals and man. These are not the only effects of ionizing radiation. The acute consequences of massive amounts of radiation that may be received accidentally or during nuclear warfare are not reviewed here (the short discussion of this subject in the 1962 report is still largely valid, at least as an introduction), nor are the effects on the nervous system and the induction of chromosome anomalies in somatic cells, which were both considered by the Committee in its 1969 report. Unlike previous reports of the Committee, the present report is submitted to the General Assembly without the technical annexes in which the evidence considered by the Committee is discussed in detail and in which the bases for the Committee's conclusions, which are stated in the report, are fully documented. However, the annexes are being made available at the same time as the report in a separate publication, issued in two volumes and the Committee wishes to draw the attention of the General Assembly to the fact that the separation of the report from the annexes is for convenience only and that major importance attaches to the scientific evidence given in the annexes.

First studies of 500-nm Cherenkov radiation from 255-MeV electrons in a diamond crystal

Energy Technology Data Exchange (ETDEWEB)

Takabayashi, Y., E-mail: takabayashi@saga-ls.jp [SAGA Light Source, 8-7 Yayoigaoka, Tosu, Saga 841-0005 (Japan); Fiks, E.I. [National Research Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); Pivovarov, Yu.L. [National Research Tomsk Polytechnic University, 634050 Tomsk (Russian Federation); National Research Tomsk State University, 634050 Tomsk (Russian Federation)

2015-06-12

The first experiment on Cherenkov light from 255-MeV electrons passing through a 50-μm-thick diamond crystal in a special geometry allowing extraction of 500-nm Cherenkov light at a right angle with respect to the electron beam direction has been performed at the injector linac of SAGA Light Source accelerator facility. The dependence of 500-nm Cherenkov light intensity (separated by a band-pass filter) on the crystal rotation angle was measured by a CCD detector. The experimentally obtained rocking curve with an intense maximum is theoretically explained as the projector effect of Cherenkov light deflected by the exit surface of the crystal. The width of the rocking curve is explained by the convolution of the standard Tamm–Frank angular distribution of Cherenkov radiation with chromatic aberration, the multiple scattering of electrons in a crystal, and initial electron beam angular divergence. In addition, it is found that the Cherenkov light intensity did not change under the (220) planar channeling condition, which is consistent with a recent theory. - Highlights: • Cherenkov light from 255-MeV electrons in a diamond crystal has been investigated. • The Cherenkov light from channeled electrons has been observed for the first time. • The experimental results are in good agreement with theory.

Development of radiation detection and measurement system - Development of scintillation radiation sensor

Energy Technology Data Exchange (ETDEWEB)

Kang, Hee Dong; Kim, Wan [Kyungpook National University, Taegu (Korea); Kim, Do Sung [Taegu University, Taegu (Korea)

2000-03-01

We have been fabricated CsI(Tl) scintillation crystals and plastic scintillators for radiation-based measuring equipment. CsI (Tl) single crystals doped with thallium as an activator were grown using the Czochralski method. The crystal structure of grown CsI(Tl) was bcc, and it was confirmed that its lattice constant was 4,568 A. The spectral range of luminescence of CsI(Tl) was 350 {approx} 700 nm independent of thallium concentration, and the fast component of the luminescence was decreased with increasing thallium concentration. The energy resolution of CsI(Tl) scintillator doped with 0.1 mole% thallium was about 9% for 137 Cs {gamma}-rays. The relation formula of {gamma}-ray energy versus energy resolution was ln(FWHM%)=-0.705ln({epsilon})+6.75. The radiation damage of CsI(Tl) increased in proportion to thallium concentration and radiation damage of CsI(Tl) increased in proportion to thallium concentration and radiation dosage, and the irradiated crystals were colored reddish. The radiation induced absorption bands appeared around 355, 425, 520 and 555 nm, and their energy level were about 3.50, 2.88, 2.39 and 2.21 eV. Plastic scintillators were fabricated thermal polymerization method. Those were polymerizing at 120 deg. C, during 72 hours, and annealing at 75 deg. C, during 24 hours. When the concentration of 1st solute was 1.5 wt% and concentration of 2nd solute was 0.01 wt%, the characteristics of scintillation were very excellent. Also 3.0 wt% tetraphenyl lead were loaded to improve the detection efficiency of {gamma}-ray. The range of emission spectrum was 400 {approx} 450nm, and the central peak was 415 nm. The radiation damage was not appear under 1*10{sup 3}Gy, but the color of plastic scintillator was changed to brown, over 1*10{sup 4}Gy exposured. 84 refs., 39 figs. (Author)

Mutagenic interactions between near-ultraviolet (365 nm) radiation and alkylating agents in Escherichia coli

International Nuclear Information System (INIS)

Moraes, E.C. de; Tyrell, R.M.

1981-01-01

The mutagenic interaction between near-ultrviolet (365 nm) radiation and the alkylting agents ehtyl methanesulponate (EMS) and methyl methanesulphonate (MMS) was studied in a repair-component and an excision-deficient stram of Escherichia coli. Near-UV raditation modified the metabolic response of of exposure to these chemicals and either reduced or increased their mutagenic efficiency. Based on these results, an experimental model was formulated to explain the mutagenic interactions that occur between near-UV and various agents that induce prototrophic reverants cia error-prone repair of DNA. According to this model, low doses of near-UV provoke conditions for mutation frequency decline (MFI) and lead to a mutagenic antagonism. With increasing near-Uv doses, damage to constitutive error-free repairs system increases, favouring the error-prone system and inhibiting the MFD. Under these conditions there will be a progressive decrease in antagonism until at high doses an enhancement of mutation frequency (positive interaction) will occur. (orig.)

Environmental gamma radiation levels around various DAE research centres

International Nuclear Information System (INIS)

Takale, R.A.; Swarnakar, M.; Shetty, P.G.; Sahu, S.K.; Pandit, G.G.

2014-01-01

This paper presents the gamma radiation levels of four research centres viz. Bhabha Atomic Research Centre (BARC), Trombay; Indira Gandhi Centre for Atomic Research (IGCAR), Kalpakkam; Variable Energy Cyclotron Centre (VECC), Kolkata; Raja Ramanna Centre for Advanced Technology (RRCAT), Indore; and an industry Board of Radiation and Isotope Technology (BRIT), Vashi. BARC is India's premier nuclear research facility and is a multi-disciplinary research centre with extensive infrastructure for advanced research and development (R and D). IGCAR, Kalpakkam is engaged in scientific research and advanced engineering programme towards the development of Fast Breeder Reactor technology. VECC Kolkata is dedicated to carry out frontier R and D in the fields of Accelerator Science and Technology, Nuclear Science (Theoretical and Experimental), and Material Science etc. RRCAT, Indore has rapidly grown into a premier institute for R and D in lasers, accelerators and their applications. BRIT, Vashi unit is involved in production, development, and supply of radioisotope based products and provision of isotope applications, radiation processing, radio analytical services etc. With an objective to keep a watch on the prevailing environmental background gamma radiation level around all the DAE installations, routine monitoring programme are being carried out using the Thermo Luminescent Dosimeters (TLDs). TLDs provide the simple, inexpensive and precise measurement of small, integrated, external gamma radiation dose rate. The general practice of this programme is to observe the outdoor gamma radiation levels. This paper summarizes the methodology and gamma radiation levels of four research centres viz. BARC, IGCAR, VECC, RRCAT and an industry BRIT, Vashi

Ambient radioactivity levels and radiation doses. Annual report 2011

International Nuclear Information System (INIS)

Bernhard-Stroel, Claudia; Hachenburger, Claudia; Trugenberger-Schnabel, Angela; Peter, Josef

2013-07-01

The annual report 2011 on ambient radioactivity levels and radiation doses covers the following issues: Part A: Natural environmental radioactivity, artificial radioactivity in the environment, occupational radiation exposure, radiation exposure from medical applications, the handling of radioactive materials and sources of ionizing radiation, non-ionizing radiation. Part B; Current data and their evaluation: Natural environmental radioactivity, artificial radioactivity in the environment, occupational radiation exposure, radiation exposure from medical applications, the handling of radioactive materials and sources of ionizing radiation, non-ionizing radiation. The Appendix includes Explanations of terms, radiation doses and related units, external and internal radiation exposure, stochastic and deterministic radiation effects, genetic radiation effects, induction of malignant neoplasm, risk assessment, physical units and glossary, laws, ordinances, guidelines, recommendations and other regulations concerning radiation protection, list of selected radionuclides.

Lethal action of ultraviolet and visible (blue violet) radiations at defined wavelengths on human lymphoblastoid cells; action spectra and interaction sites

Energy Technology Data Exchange (ETDEWEB)

Tyrrell, R.M.; Werfelli, P.; Moraes, E.C. (Institut Suisse de Recherches Experimentales sur le Cancer, Lausanne)

1984-02-01

The repair proficient human lymphoblastoid line (TK6) has been employed to construct an action spectrum for the lethal action of ultraviolet (UV) radiation in the range 254 to 434 nm and to examine possible interactions between longer (334, 365 and 405 nm) and shorter wavelength (254 and 313 nm) radiations. The action spectrum follows a DNA absorption spectrum fairly closely out to 360 nm. As in previously determined lethal action spectra for procaryotic and eucaryotic cell populations, there is a broad shoulder in the 334 to 405 nm region which could reflect the existence of either (a) a non-DNA chromophore or (b) a unique photochemical reaction in the DNA over this region. Pre-treatment with radiation at 334 or 365 nm causes either a slight sensitivity to (low fluences) or protection from (higher fluences) subsequent exposure to radiation at a shorter wavelength (254 or 313 nm). Pre-irradiation at a visible wavelength (405 nm) at all fluence levels employed sensitizes the populations to treatment with 254 or 313 nm radiations. These interactions will influence the lethal outcome of cellular exposure to broad-band radiation sources.

Lethal action of ultraviolet and visible (blue violet) radiations at defined wavelengths on human lymphoblastoid cells; action spectra and interaction sites

International Nuclear Information System (INIS)

Tyrrell, R.M.; Werfelli, P.; Moraes, E.C.

1984-01-01

The repair proficient human lymphoblastoid line (TK6) has been employed to construct an action spectrum for the lethal action of ultraviolet (UV) radiation in the range 254 to 434 nm and to examine possible interactions between longer (334, 365 and 405 nm) and shorter wavelength (254 and 313 nm) radiations. The action spectrum follows a DNA absorption spectrum fairly closely out to 360 nm. As in previously determined lethal action spectra for procaryotic and eucaryotic cell populations, there is a broad shoulder in the 334 to 405 nm region which could reflect the existence of either (a) a non-DNA chromophore or (b) a unique photochemical reaction in the DNA over this region. Pre-treatment with radiation at 334 or 365 nm causes either a slight sensitivity to (low fluences) or protection from (higher fluences) subsequent exposure to radiation at a shorter wavelength (254 or 313 nm). Pre-irradiation at a visible wavelength (405 nm) at all fluence levels employed sensitizes the populations to treatment with 254 or 313 nm radiations. These interactions will influence the lethal outcome of cellular exposure to broad-band radiation sources. (author)

Natural external radiation level and population dose in Hunan province

International Nuclear Information System (INIS)

1985-01-01

A survey of the natural external radiation level in Hunan Province is reported. The measurements were performed with FD-71 scintillation radiometers. On the basis of measurements at about 1,600 locations, the contribution from cosmic radiation is found to be 3.0 x 10 -8 Gy.h -1 , and the average absorbed dose rates in air from terrestrial γ-radiation for outdoors, indoors and roads are determined to be 9.2, 13.1 and 9.0 x 10 -8 Gy.h -1 , respectively. The γ-radiation indoors is markedly higher than that outdoors by a factor of 1.42. The lowest γ-radiation level is found in the sedimentary plain around Donting Lake, while the highest absorbed dose rates in air from terrestrial radiation are observed in some areas with exposed granites. The indoor γ-radiation in brick houses is markedly higher than that in wooden houses. Tarred roads have evidently lower radiation level than sand-gravel roads or concrete roads. The annual effective dose equivalents to the population from cosmic and terrestrial sources are 0.256 and 0.756 mSv, respectively, with a total value of 1.012 mSv

Low-level radioactive waste disposal: radiation protection laws

International Nuclear Information System (INIS)

Chapuis, A.M.; Guetat, P.; Garbay, H.

1991-01-01

The politics of radioactive waste management is a part of waste management and activity levels are one of the components of potential waste pollutions in order to assume man and environment safety. French regulations about personnel and public' radiation protection defines clearly the conditions of radioactive waste processing, storage, transport and disposal. But below some activity levels definite by radiation protection laws, any administrative procedures or processes can be applied for lack of legal regulations. So regulations context is not actually ready to allow a rational low-level radioactive waste management. 15 refs.; 4 tabs.; 3 figs

Effects of low levels of radiation on humans

International Nuclear Information System (INIS)

Auxier, J.A.

1981-01-01

The state of knowledge on effects of low-level ionizing radiations on humans is reviewed. Several problems relating to dose thresholds or lack of thresholds for several types of cancer and high LET radiations and the effects of fractionation and dose protection are discussed

Broadband superluminescent diodes with bell-shaped spectra emitting in the range from 800 to 900 nm

Energy Technology Data Exchange (ETDEWEB)

Andreeva, E V; Il' ichenko, S N; Kostin, Yu O; Lapin, P I [Superlum Diodes Ltd., Moscow (Russian Federation); Ladugin, M A; Marmalyuk, A A [Open Joint-Stock Company ' M.F. Stel' makh Polyus Research and Development Institute' , Moscow (Russian Federation); Yakubovich, S D [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)

2013-08-31

Quantum-well superluminescent diodes (SLD) with extremely thin active (AlGa)As and (InGa)As layers and centre wavelengths about 810, 840, 860 and 880 nm are experimentally studied. Their emission spectrum possesses the shape close to Gaussian, its FWHM being 30 – 60 nm depending on the length of the active channel and the level of pumping. Under cw injection, the output power of light-emitting modules based on such SLDs can amount to 1.0 – 25 mW at the output of a single-mode fibre. It is demonstrated that the operation lifetime of these devices exceeds 30000 hours. Based on the light-emitting modules the prototypes of combined BroadLighter series light sources are implemented having a bell-shaped spectrum with the width up to 100 nm. (optical radiation sources)

Diffuse radiation increases global ecosystem-level water-use efficiency

Science.gov (United States)

Moffat, A. M.; Reichstein, M.; Cescatti, A.; Knohl, A.; Zaehle, S.

2012-12-01

Current environmental changes lead not only to rising atmospheric CO2 levels and air temperature but also to changes in air pollution and thus the light quality of the solar radiation reaching the land-surface. While rising CO2 levels are thought to enhance photosynthesis and closure of stomata, thus leading to relative water savings, the effect of diffuse radiation on transpiration by plants is less clear. It has been speculated that the stimulation of photosynthesis by increased levels of diffuse light may be counteracted by higher transpiration and consequently water depletion and drought stress. Ultimately, in water co-limited systems, the overall effect of diffuse radiation will depend on the sensitivity of canopy transpiration versus photosynthesis to diffuse light, i.e. whether water-use efficiency changes with relative levels of diffuse light. Our study shows that water-use efficiency increases significantly with higher fractions of diffuse light. It uses the ecosystem-atmosphere gas-exchange observations obtained with the eddy covariance method at 29 flux tower sites. In contrast to previous global studies, the analysis is based directly on measurements of diffuse radiation. Its effect on water-use efficiency was derived by analyzing the multivariate response of carbon and water fluxes to radiation and air humidity using a purely empirical approach based on artificial neural networks. We infer that per unit change of diffuse fraction the water-use efficiency increases up to 40% depending on diffuse fraction levels and ecosystem type. Hence, in regions with increasing diffuse radiation positive effects on primary production are expected even under conditions where water is co-limiting productivity.

Effect of low-level pulsed laser 890-nm on lumbar spondylolisthesis: a case report

Science.gov (United States)

Mortazavi, Seyed M. J.; Afsharpad, Mitra; Djavid, Gholam-reza E.

2002-10-01

Objective: Evaluating the effectiveness of low-level laser therapy (LLLT) in alleviating the symptoms of lumbar spondylolisthesis. Materials and Methods: Laser was irradiated for 2 mm at six symmetric points along the lumbosacral spine and 5 points along the referred point ofpain, six times a week for 2 weeks (890 nm; 8 J/cm2; pulsed at 1500 Hz). Perception of benefit, level of function was assessed by the Oswestry disability index, lumbar mobility range of motion and low back pain intensity. Results and Discussion: Results showed a complete reduction in pain and improvement in function in the patient. This case report suggests that low-level laser therapy (LLLT) could play a role in conservative management of low-grade lumbar spondylolisthesis.

Reduction of the pool-top radiation level in HANARO

International Nuclear Information System (INIS)

Lee, Choong-Sung; Park, Sang-Jun; Kim, Heonil; Park, Yong-Chul; Choi, Young-San

1999-01-01

HANARO is an open-tank-in-pool type reactor. Pool water is the only shielding to minimize the pool top radiation level. During the power ascension test of HANARO, the measured pool top radiation level was higher than the design value because some of the activation products in the coolant reached the pool surface. In order to suppress this rising coolant, the hot water layer system (HWL) was designed and installed to maintain l.2 meter-deep hot water layer whose temperature is 5degC higher than that of the underneath pool surface. After the installation of the HWL system, however, the radiation level of the pool-top did not satisfy the design value. The operation modes of the hot water layer system and the other systems in the reactor pool, which had an effect on the formation of the hot water layer, were changed to reduce pool-top radiation level. After the above efforts, the temperature and the radioactivity distribution in the pool was measured to confirm whether this system blocked the rising coolant. The radiation level at the pool-top was significantly reduced below one tenth of that before installing the HWL and satisfied the design value. It was also confirmed by calculation that this hot water layer system would significantly reduce the release of fission gases to the reactor hall and the environment during the hypothetical accident as well. (author)

Environmental levels of microwave radiation around a satellite earth station

International Nuclear Information System (INIS)

Joyner, K.H.; Bangay, M.J.

1986-01-01

This paper discusses the background to claims of possible adverse health effects arising from exposure to environmental levels of microwave radiation around satellite earth stations. Results of a recent survey of the environmental levels of microwave radiation around two 32 metre diameter satellite communications antennas owned and operated by the Overseas Telecommunications Commission (OTC) of Australia are presented. From the measurements obtained in this survey it can be concluded that the environmental levels of microwave radiation around the OTC and similar satellite facilities do not pose a health risk to persons in the vicinity

Photosynthesis, growth, and ultraviolet irradiance absorbance of Cucurbita pepo L. leaves exposed to ultraviolet-B radiation (280 to 315 nm)

International Nuclear Information System (INIS)

Sisson, W.B.

1981-01-01

Net photosynthesis, growth, and ultraviolet (uv) radiation absorbance were determined for the first leaf of Cucurbita pepo L. exposed to two levels of uv-B irradiation and a uv-B radiation-free control treatment. Absorbance by extracted flavonoid pigments and other uv-B radiation-absorbing compounds from the first leaves increased with time and level of uv-B radiation impinging on leaf surfaces. Although absorbance of uv-B radiation by extracted pigments increased substantially, uv-B radiation attenuation apparently was insufficient to protect completely the photosynthetic apparatus or leaf growth processes. Leaf expansion was repressed by daily exposure to 1365 Joules per meter per day of biologically effective uv-B radiation by not by exposure to 660 Joules per meter per day. Photosynthesis measured through ontogenesis of the first leaf was depressed by both uv-B radiation treatments. Repression of photosynthesis by uv-B radiation was especially evident during the ontogenetic period of maximum photosynthetic activity

Physiological benefits from low levels of ionizing radiation

International Nuclear Information System (INIS)

Luckey, T.D.

1982-01-01

Extensive literature indicates that minute doses of ionizing radiation benefit animal growth and development, fecundity, health and longevity. Specific improvements appear in neurologic function, growth rate and survival of young, wound healing, immune competence, and resistance to infection, radiation morbidity, and tumor induction and growth. Decreased mortality from these debilitating factors results in increased average life span following exposure to minute doses of ionizing radiation. The above phenomena suggest the possibility that ionizing radiation may be essential for life. Limited data with protozoa suggest that reproduction rates decrease when they are maintained in subambient radiation environments. This may be interpreted to be a radiation deficiency. Evidence must now be obtained to determine whether or not ionizing radiation is essential for growth, development, nutrient utilization, fecundity, health and longevity of higher animals. Whether or not ionizing radiation is found to be essential for these physiologic functions, the evidence reviewed indicates that the optimal amount of this ubiquitous agent is imperceptibly above ambient levels. (author)

Low level laser therapy (GaAlInP 660 nm) in healing of a chronic venous ulcer: a case study

International Nuclear Information System (INIS)

Botaro, C A; Faria, L A; Oliveira, R G; Bruno, R X; Rocha, C A Q C; Paiva-Oliveira, E L

2015-01-01

The venous ulcer represents approximately 70% to 90% of inferior member ulcers, and the most common etiological factor is venous insufficiency, triggered by venous hypertension. Currently in Brazil there are several types of lasers used in physiotherapy, which benefit biological potential, emitting low power radiation, with anti-inflammatory, analgesic, healing and circulatory effects. This study aimed at the analysis of low level laser therapy effects (LLLT) on the process of tissue repair in chronic venous ulcers. We conducted a case study of a patient with a venous ulcer in the lateral region of the right inferior member. The patient underwent LLLT, which used a GaAlInP diode laser, with a wavelength of 660 nm and energy density of 4 J cm −2 applied punctually at the edges of the wound, with an average distance of 1 cm between the points with a pen-laser perpendicular wrapped in paper and a plastic wrap, keeping contact with the tissue. After four months of therapy and a total of 21 sessions, an improvement was noticeable in the gross appearance of the wound, but after a month and a half without therapy, the dimensions of the wound increased in length and width. Analyzing the results of this case study allows us to conclude that the LLLT GaAlInP (660 nm) with an energy density of 4 J cm −2 , was not successful in the healing of venous ulcers. (paper)

Low level laser therapy (GaAlInP 660 nm) in healing of a chronic venous ulcer: a case study

Science.gov (United States)

Botaro, C. A.; Faria, L. A.; Oliveira, R. G.; Bruno, R. X.; Rocha, C. A. Q. C.; Paiva-Oliveira, E. L.

2015-07-01

The venous ulcer represents approximately 70% to 90% of inferior member ulcers, and the most common etiological factor is venous insufficiency, triggered by venous hypertension. Currently in Brazil there are several types of lasers used in physiotherapy, which benefit biological potential, emitting low power radiation, with anti-inflammatory, analgesic, healing and circulatory effects. This study aimed at the analysis of low level laser therapy effects (LLLT) on the process of tissue repair in chronic venous ulcers. We conducted a case study of a patient with a venous ulcer in the lateral region of the right inferior member. The patient underwent LLLT, which used a GaAlInP diode laser, with a wavelength of 660 nm and energy density of 4 J cm-2 applied punctually at the edges of the wound, with an average distance of 1 cm between the points with a pen-laser perpendicular wrapped in paper and a plastic wrap, keeping contact with the tissue. After four months of therapy and a total of 21 sessions, an improvement was noticeable in the gross appearance of the wound, but after a month and a half without therapy, the dimensions of the wound increased in length and width. Analyzing the results of this case study allows us to conclude that the LLLT GaAlInP (660 nm) with an energy density of 4 J cm-2, was not successful in the healing of venous ulcers.

A knowledge and awareness level survey of radiation protection among the radiation workers in Henan Province

International Nuclear Information System (INIS)

Cheng, Xiao-jun; Tian, Chong-bin; Zhang, Qin-fu; Liu, Cheng; Ding, Li

2008-01-01

Full text: Objective: To reveal the knowledge and awareness level of radiation protection among radiation workers in Henan province and to explore the methods to improve it. Methods: A questionnaire survey was carried out among 208 radiation workers. Results: The correct rate of the answer to radiation protection knowledge from radiation workers in Henan province is 53.78%. Most of them (88.9%) realized that it is important to protect patients and their companions. They adhere to the principles of justification of medial exposure and optimization of radiation protection and follow the management system of radiation protection. However, a few workers didn't follow the principles strictly. Sometime, during the radio diagnosis and radiotherapy services, the patients and their companions were not well protected from the radiation, and some patients were given unnecessary X-ray examine. Even worse, some workers did not attach importance to the regulations of radiation protection and disobey them frequently. Again, some hospital leaders disregard the regulation of radiation protection and didn't follow the regulation of health surveillance and radiation protection monitoring properly. And those behaviors and attitude, in fact, influence some workers' attitude to radiation protection. Conclusion: The level of radiation protection knowledge and awareness among the radiation workers in Henan province needs to be improved. It is necessary to strengthen radiation protection knowledge by strengthening training, and to improve safety awareness among the radiation staff, and, more important, the hospital leaders as well. (author)

Array-level stability enhancement of 50 nm AlxOy ReRAM

Science.gov (United States)

Iwasaki, Tomoko Ogura; Ning, Sheyang; Yamazawa, Hiroki; Takeuchi, Ken

2015-12-01

ReRAM's low voltage and low current programmability are attractive features to solve the scaling issues of conventional floating gate Flash. However, read instability in ReRAM is a critical issue, due to random telegraph noise (RTN), sensitivity to disturb and retention. In this work, the array-level characteristics of read stability in 50 nm AlxOy ReRAM are investigated and a circuit technique to improve stability is proposed and evaluated. First, in order to quantitatively assess memory cell stability, a method of stability characterization is defined. Next, based on this methodology, a proposal to improve read stability, called ;stability check loop; is evaluated. The stability check loop is a stability verification procedure, by which, instability improvement of 7×, and read error rate improvement of 40% are obtained.

Measurement uncertainty in broadband radiofrequency radiation level measurements

Directory of Open Access Journals (Sweden)

Vulević Branislav D.

2014-01-01

Full Text Available For the evaluation of measurement uncertainty in the measurement of broadband radio frequency radiation, in this paper we propose a new approach based on the experience of the authors of the paper with measurements of radiofrequency electric field levels conducted in residential areas of Belgrade and over 35 municipalities in Serbia. The main objective of the paper is to present practical solutions in the evaluation of broadband measurement uncertainty for the in-situ RF radiation levels. [Projekat Ministarstva nauke Republike Srbije, br. III43009

The analysis of radiation levels for daily supplies made in Korea

Energy Technology Data Exchange (ETDEWEB)

Kim, H.R. [Ulsan National Inst. of Science and Tech., Ulsan (Korea, Republic of)

2014-07-01

The radiation levels were measured and assessed for samples around a living environment such as building materials and industrial products for which civil complaint had been filed to have radioactivity in Korea. The dose rates for more than one hundred samples from the goods in a living environment were compared with those of the background. The sample's radiation level ranged from 0.095 μSv/h to 0.162 μSv/h, which are within the range of the laboratory background level from 0.090 μSv/h to 0.174 μSv/h. It was thought the radiation level of the goods for which the civil complaint was given had not particular difference from the environmental radiation level in Korea in spite of deviations for some samples. (author)

Biological monitors for low levels of ionising radiation

International Nuclear Information System (INIS)

Mohankumar, M.N.; Jeevanram, R.K.

1995-01-01

The biological effects of high doses of ionising radiation are well understood and the methods of measurement of these doses well established. However the effects due to extremely low doses remain by and large uncertain. This is because of the fact that at such low doses no gross symptoms are seen. In fact, at these levels the occurrence of double strand breaks leading to the formation of chromosomal aberrations like dicentrics is rare and chances of mutation due to base damage are negligible. Hence neither chromosomal aberration studies nor mutational assays are useful for detecting doses of the order of a few milligray. Results of exhaustive work done by various laboratories indicate that below 20 mGy the chromosomal aberration technique based on scoring of dicentrics cannot distinguish between a linear or a threshold model. However indirect methods like unscheduled DNA synthesis (UDS) and sister chromatid exchanges (SCEs) appear to be promising for the detection of radiation exposures due to low levels of radiation. This report reviews the available literature on the biological effects of low levels of ionising radiation and highlights the merits and demerits of the various methods employed in the measurement of UDS and SCE. The phenomenon of radio-adaptive response (RAR) and its relation to DNA repair is also discussed. (author)

Solar radiation measurements at the network of six sites in the UK, January - December 2001

Energy Technology Data Exchange (ETDEWEB)

Driscoll, C.M.H.; Campbell, J.I.; Pearson, A.J.; Grainger, K.J.L.; Dean, S.F.; Clark, I.E

2002-04-01

A summary of the results from January to December 2001 of a survey of solar radiation levels at the UK network of six solar radiation measurement sites is presented. The network consists of three NRPB sites at Chilton, Leeds and (monitoring since 1988) and three Meteorological Office stations at Camborne, Kinloss and Lerwick (monitoring since 1993). Visible (400-770 nm), ultraviolet UVA radiation (320-400 nm) and erythemally weighted ultraviolet radiation UVR{sub eff} (280-400 nm) have been measured simultaneously using a three detector measurement system. Results are compared with calculated irradiances of ultraviolet radiation and published illuminance data, and with data for the measurement period from 1988 to 2000. Yearly reports have been produced for selected sites, giving the daily solar index (which is a measure of the sunburn potential for sensitive skin types) throughout the year. (author)

Solar radiation measurements at the network of six sites in the UK, January - December 2001

International Nuclear Information System (INIS)

Driscoll, C.M.H.; Campbell, J.I.; Pearson, A.J.; Grainger, K.J.L.; Dean, S.F.; Clark, I.E.

2002-01-01

A summary of the results from January to December 2001 of a survey of solar radiation levels at the UK network of six solar radiation measurement sites is presented. The network consists of three NRPB sites at Chilton, Leeds and (monitoring since 1988) and three Meteorological Office stations at Camborne, Kinloss and Lerwick (monitoring since 1993). Visible (400-770 nm), ultraviolet UVA radiation (320-400 nm) and erythemally weighted ultraviolet radiation UVR eff (280-400 nm) have been measured simultaneously using a three detector measurement system. Results are compared with calculated irradiances of ultraviolet radiation and published illuminance data, and with data for the measurement period from 1988 to 2000. Yearly reports have been produced for selected sites, giving the daily solar index (which is a measure of the sunburn potential for sensitive skin types) throughout the year. (author)

The effect of the operation modes of a gas discharge low-pressure amalgam lamp on the intensity of generation of 185 nm UV vacuum radiation

Energy Technology Data Exchange (ETDEWEB)

Vasilyak, L. M., E-mail: vasilyak@ihed.ras.ru [Russian Academy of Sciences, Joint Institute of High Temperatures (Russian Federation); Drozdov, L. A., E-mail: lit@npo.lit.ru; Kostyuchenko, S. V.; Sokolov, D. V. [ZAO LIT (Russian Federation); Kudryavtsev, N. N.; Sobur, D. A., E-mail: soburda@gmail.com [Moscow Institute for Physics and Technology (Russian Federation)

2011-12-15

The effect of the discharge current, mercury vapor pressure, and the inert gas pressure on the intensity and efficiency of the 185 nm line generation are considered. The spectra of the UV radiation (vacuum ultraviolet) transmission by protective coatings from the oxides of rare earth metals and aluminum are investigated.

Biological effects of low-level ionizing and non-ionizing radiation

International Nuclear Information System (INIS)

Upton, A.C.

1986-01-01

Early in this century it was recognized that large doses of ionizing radiation could injure almost any tissue in the body, but small doses were generally thought to be harmless. By the middle of the century however it came to be suspected that even the smallest doses of ionizing radiation to the gonads might increase the risk of hereditary disease in subsequently-conceived offspring. Since then the hypothesis that carcinogenic and teratogenic effects also have no threshold has been adopted for purposes of radiological protection. It is estimated nevertheless that the risks that may be associated with natural background levels of ionizing irradiation are too small to be detectable. Hence validation of such risk estimates will depend on further elucidation of the dose-effect relationships and mechanisms of the effects in question, through studies at higher dose levels. In contrast to the situation with ionizing radiation, exposure to natural background levels of ultraviolet radiation has been implicated definitively in the etiology of skin cancers in fair-skinned individuals. Persons with inherited effects in DNA repair capacity are particularly susceptible. Non-ionizing radiations of other types can also affect health at high dose levels, but whether they can cause injury at low levels of exposure is not known

Environmental radiation levels in and around Kalpakkam during 1983-1987

International Nuclear Information System (INIS)

Nambi, K.S.V.; Mehta, N.K.; Sundaram, Meenakshi; Viswambharan, K.R.

1989-01-01

Results of the environmental radiation monitoring around the Kalpakkam Atomic Power Station carried out routinely on quarterly integrating cycles using thermoluminescent dosimeters, are presented and analysed, for the five year period 1983-87. As the first reactor attained criticality in July 1983 and the second unit in August 1985 the results are compared with the previously published values for the period 1980-82. Only at two locations viz. the Micro-met laboratory situated at 800 meters from the station and the main gate located at the 1.6 km exclusion zone boundary, a possible indication of increases in the environmental radiation level associated with the power reactor operations could be discerned. However these were found to be statistically insignificant. The whole terrain is characterised by somewhat high levels of terrestrial radiations with quite wide temporal fluctuations which easily mask the small increases if any in the radiation levels, contributed by the reactors. Places located farther away from the power station and away from the monazite-bearing beaches, yielded an annual average background level of 117 ± 29 mR as against the value of 125 ± 24 mR obtained during the preoperational period of 1980-82. A declining general trend in the radiation levels is seen at many locations and this is thought to be associated with significant reduction in the 137 Cs fallout component of the environmental radiation. (author). 5 refs., 2 tabs., 11 figs

Radiation levels in nuclear diagnostic examinations

International Nuclear Information System (INIS)

Vermeulen, A.M.T.I.

1987-01-01

To estimate the risks for a pregnant radiological worker, radiation level measurements are executed for common nuclear diagnostic techniques. These measurements are combined with the time which the radiologic worker is present during the performance of the diagnostic techniques. It is concluded that a radiologic worker is receiving less than 5 mSv during pregnancy. This is the case with in vivo determination in a department of nuclear medicine with common diagnostic techniques. Reduction of radiation doses during pregnancy is possible by reduction of heart function examinations, skeletal examinations and brain scans. 1 figure; 13 tabs

Somatic and genetic effects of low-level radiation

International Nuclear Information System (INIS)

Upton, A.C.

1974-01-01

Although the biological effects of ionizing radiation are probably better known than those of any other physical or chemical agent in the environment, our information about such effects has come from observations at doses and dose rates which are orders of magnitude higher than natural background environmental radiation levels. Whether, therefore biological effects occur in response to such low levels can be estimated only by extrapolation, based on assumptions about the dose-effect relationship and the mechanisms of the effects in question. Present knowledge suggests the possibility that several types of biological effects may result from low-level irradiation. The induction of heritable genetic changes in germ cells and carcinogenic changes in somatic cells are considered to be the most important from the standpoint of their potential threat to health. On the basis of existing data, it is possible to make only tentative upper limit estimates of the risks of these effects at low doses. The estimates imply that the frequency of such effects attributable to exposure at natural background radiation levels would constitute only a small fraction of their natural incidence. 148 references

Super ACO FEL oscillation at 300 nm

CERN Document Server

Nutarelli, D; Renault, E; Nahon, L; Couprie, Marie Emmanuelle

2000-01-01

Some recent improvements, involving both the optical cavity mirrors and the positron beam dynamics in the storage ring, have allowed us to achieve a laser oscillation at 300 nm on the Super ACO Storage Ring FEL. The Super ACO storage ring is operated at 800 MeV which is the nominal energy for the usual synchrotron radiation users, and the highest energy for a storage ring FEL. The lasing at 300 nm could be kept during 2 h per injection, with a stored current ranging between 30 and 60 mA. The FEL characteristics are presented here. The longitudinal stability and the FEL optics behaviour are also discussed.

The in vitro photolysis of whole rat lenses using focused 290nm laser radiation

International Nuclear Information System (INIS)

Hibbard, L.B.; Kirk, N.J.; Borkman, R.F.

1985-01-01

Whole rat lenses have been irradiated with a UV laser at 290 or 298 nm focused to a 0.08 mm diameter spot. The irradiated spot was analyzed using fluorescence spectroscopy and it was observed that the intensity of fluorescence fell as the irradiation proceeded. These observations were interpreted in terms of a model which postulates photolysis of tryptophan, primarily present as residues in lens proteins, and formation of photoproducts which absorb the UV laser radiation to an ever-increasing extent as the irradiation proceeds. Evidence is also presented which indicates that an observed fast component of the tryptophan fluorescence decay results from local heating of the lens tissues due to energy dissipation by the laser. Tryptophan residues can be photolyzed by UV light in the whole lens, in vitro, in a fashion entirely analogous to that reported previously only for lens protein solutions. The photochemical behavior of lens protein solutions is relevant to whole lens photolysis and no special protective mechanism appears to be operative in the intact organ. (author)

Risks of low-level radiation - the evidence of epidemiology

International Nuclear Information System (INIS)

Gloag, D.

1980-01-01

The difficulties involved in estimating risks from very low levels of radiation and the use of dose-response models for cancer incidence are discussed with reference to the third BEIR Committee report on the Effects on Populations of Exposure to low levels of Ionizing Radiation (1980). Cancer risk estimates derived from different epidemiological studies are reviewed. They include atom bomb survivors, medically irradiated groups and occupational groups. (36 references). (author)

Human exposure to low level ionising radiation

International Nuclear Information System (INIS)

Paix, David

1988-01-01

This paper describes the low-level radiation sources and their effects on human populations, from a global perspective. 'Low-level' means exposures in the range of the natural background to which everybody is exposed. The quoted values are whole-world averages, but individual variations are mentioned in a few cases. (author). 22 refs

Evaluating natural radiation level by existing airborne radioactive data

International Nuclear Information System (INIS)

Mingkao, Hu; Changqing, Han; Jiangqi, Fang; Zhengxin, Shen

2002-01-01

Airborne Survey and Remote Sensing Center of Nuclear Industry, founded in the middle of 1950s, is a unique unit specialized in uranium exploration by airborne radioactive survey in China. Large numbers of airborne data of radioactivity and abundant experience have been accumulated for more than 40 years. All-round detailed investigation of environmental radiation levels in our country will not be completed in the near future. Thus, at present it is considered to evaluate natural radiation levels using the existing radioactive data. This paper introduces the results of analysis and study comparing airborne radioactive data for radiation environmental evaluation obtained from survey area in Gansu, China, in the 2001 with the measurement results by ground gamma ray radiation dose-rate instrument for environment. The air-earth inter-comparison error does not exceed 30% at radiation fields with a definite area, and the air-earth inter-comparison error does not exceed 60% at outcrop of granite. In 6km long profile that has various circumstances, such as desert, Gobi, farmland and residential area, minimum of air absorbed dose rate is 47nGy/h at an altitude of 1 meter above the soil plane, maximum is 68nGy/h. The inter-comparison errors are usually less than 20%, and maximum is 25.38%. This shows that it is feasible to obtain natural radiation levels rapidly if we could use the existing radioactive data adequately and make some correction, such as geology factor

Review of the controversy on risks from low levels of radiation

International Nuclear Information System (INIS)

Higson, D.

2001-01-01

The need for regulation of low levels of radiation exposure, and the estimation of risks from such exposures, are based on the assumption that risk is proportional to dose without a threshold, the 'linear no-threshold (LNT) hypothesis'. This assumption is not supported by scientific data. There is no clear evidence of harm from low levels of exposure, up to at least 20 mSv (acute dose) or total dose rates of at least 50 mSv per year. Even allowing for reasonable extrapolation from radiation levels at which harmful effects have been observed, the LNT assumption should not be used to estimate risks from doses less than 100 mSv. Laboratory and epidemiological evidence, and evolutionary expectations of biological effects from low level radiation, suggest that beneficial health effects (sometimes called 'radiation hormesis') are at least as likely as harmful effects from such exposures. Controversy on this matter strikes at the basis of radiation protection practice

Cosmic radiation doses at flight level altitudes of airliners

International Nuclear Information System (INIS)

Viragh, E.; Petr, I.

1985-01-01

Changes are discussed in flux density of cosmic radiation particles with time as are the origin of cosmic radiation, the level of cosmic radiation near the Earth's surface, and the determination of cosmic radiation doses in airliners. Doses and dose rates are given measured on different flight routes. In spite of the fact that the flight duration at an altitude of about 10 km makes for about 80% of the total flight time, the overall radiation burden of the crews at 1000 flight hours a year is roughly double that of the rest of the population. (J.C.)

Basal body and striated rootlet changes in primate macular retinal pigmented epithelium after low level diffuse argon laser radiation. Final report 1981-1982

Energy Technology Data Exchange (ETDEWEB)

Schuschereba, S.T.; Zwick, H.; Stuck, B.E.; Beatrice, E.S.

1982-09-01

Basal bodies or centrioles (BB - microtubule organizing centers) and striated rootlets (SR - bundles of 60 A action-like filaments) have a close association in primate retinal pigmented epithelial (RPE) cells. The frequency of occurrence of these structures was evaluated in the macular RPE after repeated exposure to low level diffuse argon laser radiation (DALR). The awake chaired animal's head was restrained and positioned near the center of the 0.75 m hemisphere which was diffusely irradiated with 514.5 nm laser radiation. The right eye of each subject was occluded during the two-hour exposure session. The first subject received 24 cumulative hours of exposure, the second, 40 hours and the third, 42 hours.

Biological monitors for low levels of ionising radiation

Energy Technology Data Exchange (ETDEWEB)

Mohankumar, M N; Jeevanram, R K [Safety Research and Health Physics Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

1996-12-31

The biological effects of high doses of ionising radiation are well understood and the methods of measurement of these doses well established. However the effects due to extremely low doses remain by and large uncertain. This is because of the fact that at such low doses no gross symptoms are seen. In fact, at these levels the occurrence of double strand breaks leading to the formation of chromosomal aberrations like dicentrics is rare and chances of mutation due to base damage are negligible. Hence neither chromosomal aberration studies nor mutational assays are useful for detecting doses of the order of a few milligray. Results of exhaustive work done by various laboratories indicate that below 20 mGy the chromosomal aberration technique based on scoring of dicentrics cannot distinguish between a linear or a threshold model. However indirect methods like unscheduled DNA synthesis (UDS) and sister chromatid exchanges (SCEs) appear to be promising for the detection of radiation exposures due to low levels of radiation. This report reviews the available literature on the biological effects of low levels of ionising radiation and highlights the merits and demerits of the various methods employed in the measurement of UDS and SCE. The phenomenon of radio-adaptive response (RAR) and its relation to DNA repair is also discussed. (author). 98 refs., 11 figs., 4 tabs.

Knowledge of medical imaging radiation dose and risk among doctors

International Nuclear Information System (INIS)

Brown, Nicholas; Jones, Lee

2013-01-01

The growth of computed tomography (CT) and nuclear medicine (NM) scans has revolutionised healthcare but also greatly increased population radiation doses. Overuse of diagnostic radiation is becoming a feature of medical practice, leading to possible unnecessary radiation exposures and lifetime-risks of developing cancer. Doctors across all medical specialties and experience levels were surveyed to determine their knowledge of radiation doses and potential risks associated with some diagnostic imaging. A survey relating to knowledge and understanding of medical imaging radiation was distributed to doctors at 14 major Queensland public hospitals, as well as fellows and trainees in radiology, emergency medicine and general practice. From 608 valid responses, only 17.3% correctly estimated the radiation dose from CT scans and almost 1 in 10 incorrectly believed that CT radiation is not associated with any increased lifetime risk of developing cancer. There is a strong inverse relationship between a clinician's experience and their knowledge of CT radiation dose and risks, even among radiologists. More than a third (35.7%) of doctors incorrectly believed that typical NM imaging either does not use ionising radiation or emits doses equal to or less than a standard chest radiograph. Knowledge of CT and NM radiation doses is poor across all specialties, and there is a significant inverse relationship between experience and awareness of CT dose and risk. Despite having a poor understanding of these concepts, most doctors claim to consider them prior to requesting scans and when discussing potential risks with patients.

Low-level radiation and cancer deaths

International Nuclear Information System (INIS)

Sanders, B.S.

1978-01-01

It is stated that although the proportion of cancer deaths among males is somewhat higher for Hanford employees with recorded occupational radiation exposure compared with males in the general population of the State of Washington, there is no indication that radiation is the cause of this difference. Statistics are given for mean doses received and for deaths from cancer and other causes for male employees. It is shown that for each year the mean dose level of those who died from cancer is not significantly different from the mean of those who died from other causes. The mean dose level for the majority of those who died in a specific year is lower than the mean for the survivors in the year of death, in the year preceding the year of death, or in the two years preceding the year of death. This is true whether the mean was for those dying from cancer or from other causes. These relationships are similar for female exposed employees and agree with other similar studies. The latest analysis on longevity of exposed male Hanford employees vs those nonexposed and the out-of-plant controls from date of hire to April 1974 are considered and show no firm indication of any lasting adverse health effects among employees attributable to occupational exposure to radiation within permissible limits. (U.K.)

Ecological and nonhuman biological effects of solar UV-B radiation

International Nuclear Information System (INIS)

Worrest, R.C.

1984-01-01

Recent studies regarding the impact of UV-B radiation upon ecological and nonhuman biological systems is the subject of the report. For years scientists and laymen alike have causally noted the impact of solar ultraviolet radiation upon the nonhuman component of the biosphere. Stratospheric ozone functions effectively as an ultraviolet screen by filtering out solar radiation in the 220-320 nm waveband as it penetrates through the atmosphere, thus allowing only small amounts of the longer wavelengths of radiation in the waveband to leak through to the surface of the earth. Although this radiation (UV-B radiation, 290-320 nm) comprises only a small fraction (lesser tha 1%) of the total solar spectrum, it can have a major impact on biological systems due to its actinic nature. Many organic molecules, most notably DNA, absorb UV-B radiation which can initiate photochemical reactions. It is life's ability, or lack thereof, to cope with enhanced levels of solar UV-B radiation that has generated concern over the potential depletion of stratospheric ozone

1090 nm infrared radiation at close to threshold dose induces cataract with a time delay.

Science.gov (United States)

Yu, Zhaohua; Schulmeister, Karl; Talebizadeh, Nooshin; Kronschläger, Martin; Söderberg, Per G

2015-03-01

To investigate whether infrared radiation (IRR)-induced cataract is instant or is associated with a time delay between the exposure and the onset of lens light scattering after an exposure to just above threshold dose. Six-weeks-old albino Sprague-Dawley female rats were unilaterally exposed to 197 W/cm2 IRR at 1090 nm within the dilated pupil. In the first experiment, the animals were exposed with four exposure times of 5, 8, 13 and 20 second, respectively. At 24 hr after exposure, the light scattering in both exposed and contralateral not exposed lenses was measured. Based on the first experiment, four postexposure time groups were exposed unilaterally to 1090 nm IRR of 197 W/cm2 for 8 second. At 6, 18, 55 and 168 hr after exposure, the light scattering in both lenses was measured. A 197 W/cm2 IRR-induced light scattering in the lens with exposures of at least 8 second. Further, after exposure to IRR of 197 W/cm2 for 8 second, the light-scattering increase in the lens was delayed approximately 16 hr after the exposure. There is a time delay between the exposure and the onset of cataract after exposure to close to threshold dose implicating that either near IRR cataract is photochemical or there is a time delay in the biological expression of thermally induced damage. © 2014 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Legislation and litigation related to low-level radiation injury claims

International Nuclear Information System (INIS)

McCraw, T.

1985-01-01

Current legislation and litigation related to radiation exposure will have an enormous impact on the radiation protection and monitoring requirements of the future. A brief review of some proposed injury compensation bills for veterans and a recent court decision for low-level radiation injury claims are reviewed

50W CW output power and 12mJ pulses from a quasi-2-level Yb:YAG ceramic rod laser end-pumped at the 969nm zero-phonon line

Science.gov (United States)

Fries, Christian; Weitz, Marco; Theobald, Christian; v. Löwis of Menar, Patric; Bartschke, Jürgen; L'huillier, Johannes A.

2015-02-01

With the advent of high power and narrow bandwidth 969 nm pump diodes, direct pumping into the upper laser level of Yb:YAG and hence quasi-2-level lasers became possible. Pumping directly into the emitting level leads to higher quantum efficiency and reduction of non-radiative decay. Consequently, thermal load, thermal lensing and risk of fracture are reduced significantly. Moreover pump saturation and thermal population of uninvolved energy-levels in ground and excited states are benefical for a homogenous distribution of the pump beam as well as the reduction of reabsorption loss compared to 3-level systems, which allows for high-power DPSS lasers. Beside continuous-wave (cw) operation, nanosecond pulses with a repetition rate between 1 and 5 kHz are an attractive alternative to flashlamp-pumped systems (10-100 Hz) in various measurement applications that require higher data acquisition rates because of new faster detectors. Based on measurements of the absorption and a detailed numerical model for pump beam distribution, including beam propagation and saturation factors, power-scaling of a ceramic rod Yb:YAG oscillator was possible. Finally a cw output power of 50 W with 33 % pump efficiency at 1030 nm has been demonstrated (M2 dumping of this system. The cavity-dumped setup allowed for 3-10 ns pulses with a pulse energy of 12.5 mJ at 1 kHz (M2 < 1.1). In order to achieve these results a systematic experimental and numerical investigation on gain dynamics and the identification of different stable operating regimes has been carried out.

The Radiation Levels for Household Goods Made in Korea

International Nuclear Information System (INIS)

Kim, Hee Reyoung; Park, Doo Won; Lee, Wan No; Choi, Sang Do; Chung, Kun Ho; Kang, Mun Ja; Choi, Geun Sik; Lee, Chang Woo

2008-01-01

The environmental radiation based on a natural and artificial radiation always exists in the environment. The natural radiation includes cosmic ray coming into the atmosphere from outer space, radiation emitted from the earth's crust or soil, radiation by the radon in the air and its progenies. These natural radiation comes from various buildings like a house and an apartment, agricultural and stock breeding products like rice and milk, and a body, etc. The artificial radiation emanates from a nuclear power plant, a radioisotope facility, a radioactive waste disposal site, a medical or research facility treating a radioactive material, a radiation generation device for an industry, TV, a microwave oven, appliances like a fluorescent clock, an airport security table, etc. Among the various kinds of radioactive nuclides that existed in the earth's crust at the time of the earth's formation about 4,000 million years ago, all the short half life nuclides decayed and the long half life nuclides remain amid the nuclides of a half life with more than 100 million years and their progenies now. In fact, the natural radiation level is determined by the nuclides of the Thorium series which have K-40 (half life 1.25 billion years), Th-232 (half life 14.5 billion years) as a parent nuclide, the nuclides of the uranium series which have U-238 (half life 4.5 billon years) as a parent nuclide, and the cosmic ray like photon and muon. These nuclides are distributed in the soil, sea water, construction material and body with different concentrations. Different radiation dose rates are presented in different regions due to the different concentrations of the radioactive minerals included at the materials. Actually, Brazil and India reveal a relatively high natural radiation level

Studies on the natural radiation levels around the Caspian sea area

International Nuclear Information System (INIS)

Akbari, R.B.

1993-01-01

We measured about 80 items from four areas of Mazandaran, randomly selected samples of food products, soil and water, around the shore of the Caspian sea area. The results showed that the natural radioactivity in beans and broad beans in some areas is much more than in others. The results were also compared with the levels of radiations from some materials from Brazil, which also contained high levels of radiations. Samples measured in this study showed higher levels of radiations than the American food products. (author). 12 refs, 8 tabs

Increase of the photosensitivity of undoped poly(methylmethacrylate) under UV radiation at 325 nm

DEFF Research Database (Denmark)

Sáez-Rodríguez, D.; Nielsen, Kristian; Bang, Ole

2014-01-01

in undoped PMMA mPOFs with a hexagonal structure of three rings in the inner cladding. Two sets of FBGs were inscribed at two different resonant wavelengths (827 nm and 1562 nm) at different strains using an UV He-Cd laser at 325 nm focused by a lens and scanned over the fibre. We observed an increase...

Creation and investigation of powerful EUV sources (λ ∼ 13.5 nm)

International Nuclear Information System (INIS)

Borisov, V. M.; Borisova, G. N.; Vinokhodov, A. Yu.; Ivanov, A. S.; Kiryukhin, Yu. B.; Mishchenko, V. A.; Prokofiev, A. V.; Khristoforov, O. B.

2010-01-01

Results are presented from experimental studies of repetitively pulsed EUV (λ = 13.5 ± 0.135 nm) sources based on a laser-initiated discharge in tin vapor between rotating disk electrodes. Radiative characteristics of two sources with different systems of tin supply onto the electrode surface and different types of power supply have been compared. A number of new effects have been revealed at pulse repetition rates as high as ∼4000 Hz. A mean radiation power of 520 W into the 2π solid angle has been achieved in the spectral band 13.5 ± 0.135 nm at a deposited electrical power of 24 kW.

Creation and investigation of powerful EUV sources (λ ≈ 13.5 nm)

Science.gov (United States)

Borisov, V. M.; Borisova, G. N.; Vinokhodov, A. Yu.; Ivanov, A. S.; Kiryukhin, Yu. B.; Mishchenko, V. A.; Prokofiev, A. V.; Khristoforov, O. B.

2010-03-01

Results are presented from experimental studies of repetitively pulsed EUV (λ = 13.5 ± 0.135 nm) sources based on a laser-initiated discharge in tin vapor between rotating disk electrodes. Radiative characteristics of two sources with different systems of tin supply onto the electrode surface and different types of power supply have been compared. A number of new effects have been revealed at pulse repetition rates as high as ˜4000 Hz. A mean radiation power of 520 W into the 2π solid angle has been achieved in the spectral band 13.5 ± 0.135 nm at a deposited electrical power of 24 kW.

Mutagenesis and cytotoxicity in human epithelial cells by far- and near-ultraviolet radiations: action spectra

International Nuclear Information System (INIS)

Jones, C.A.; Huberman, E.; Cunningham, M.L.; Peak, M.J.

1987-01-01

Action spectra were determined for cell killing and mutation by monochromatic ultraviolet and visible radiations (254-434 nm) in cultured human epithelial P3 cells. Cell killing was more efficient following radiation at the shorter wavelengths (254-434 nm) than at longer wavelengths (365-434 nm). At 254 nm, for example, a fluence of 11 Jm-2 gave 37% cell survival, while at 365 nm, 17 X 10(5) Jm-2 gave equivalent survival. At 434 nm little killing was observed with fluences up to 3 X 10(6) Jm-2. Mutant induction, determined at the hypoxanthine-guanine phosphoribosyltransferase locus, was caused by radiation at 254, 313, and 365 nm. There was no mutant induction at 334 nm although this wavelength was highly cytotoxic. Mutagenesis was not induced by 434 nm radiation, either. There was a weak response at 405 nm; the mutant frequencies were only slightly increased above background levels. For the mutagenic wavelengths, log-log plots of the mutation frequency against fluence showed linear regressions with positive slopes of 2.5, consistent with data from a previous study using Escherichia coli. The data points of the action spectra for lethality and mutagenesis were similar to the spectrum for DNA damage at wavelengths shorter than 313 nm, whereas at longer wavelengths the lethality spectrum had a shoulder, and the mutagenesis spectrum had a secondary peak at 365 nm. No correlation was observed for the P3 cells between the spectra for cell killing and mutagenesis caused by wavelengths longer than 313 nm and the induction of DNA breakage or the formation of DNA-to-protein covalent bonds in these cells

Level of Radiofrequency (RF) Radiations from GSM Base Stations ...

African Journals Online (AJOL)

Levels of radiofrequency radiations around two global systems for mobile communication (GSM) base stations located in the vicinity of a residential quarter and workplace complex were measured. The effects of the radiofrequency radiations on albino mice placed in exposure cages and located around the base stations ...

Investigation of the relationship between knowledge concerning radiation and the level of anxiety toward radiation in student nurses

International Nuclear Information System (INIS)

Kunugita, Naoki

2008-01-01

In the medical fields, the use of radiation is indispensable in diagnosis, radiotherapy, nuclear medicine and various other areas. On the other hand, great anxiety is often felt due to the misunderstanding of radiation, and this anxiety is seen in not only patients but also nurses. In this study, a questionnaire survey about knowledge of radiation and the level of anxiety was carried out in student nurses for three years from 2005 to 2007. The questionnaire included the level of anxiety about radiation and 12 basic question items concerning radiation. The results showed that the student with poor knowledge about radiation showed high anxiety. After a series of lectures concerning radiation, the acquisition of knowledge and a decrease in anxiety were observed in the students. However, it was still shown that people with scarce knowledge concerning radiation still had high anxiety at the end of the lectures. In conclusion, it was shown that education about radiation is necessary to decrease anxiety about radiation among nurses in medical care. (author)

SIRAD – Personal radiation detectors

International Nuclear Information System (INIS)

Alnawaf, Hani; Butson, Martin J.; Yu, Peter K.N.; Cheung, Tsang

2011-01-01

SIRAD badge dosimeters provide a visual qualitative measurement of exposure to radiation for mid range dose exposure. This is performed using an active radiochromic dosimeter in a transparent window, combined into a badge assembly. When irradiated, the badges active window turns blue, which can be matched against the given colour chart for a qualitative assessment of the exposure received. Two peaks in the absorption spectra located at 617 nm and 567 nm were found. When analysed with a common computer desktop scanner, the optical density response of the film to radiation exposure is non-linear but reproducible. The net OD of the film was 0.21 when exposed to 50cGyand 0.31 at 200 cGy exposure when irradiated with a 6 MV x-ray energy beam and analysed using a broad spectrum light source. These values reduced when exposed with kilovoltage x-rays with an approximate 30% reducing in sensitivity at 50 kVp. The film provides an adequate measurement and visually qualitative assessment of radiation exposure for levels in the range of 0–50 cGy.

Modification of genetic effects of gamma radiation by laser radiation

International Nuclear Information System (INIS)

Khotyljova, L.V.; Khokhlova, S.A.; Khokhlov, I.V.

1988-01-01

Full text: Mutants obtained by means of ionizing radiation and chemical mutagens often show low viability and productivity that makes their use in plant breeding difficult. Methods reducing the destructive mutagen action on important functions of plant organism and increasing quality and practical value of induced mutants would be interesting. We believe that one method for increasing efficiency of experimental mutagenesis in plants is the application of laser radiation as a modificator of genetic effects of ionizing radiation and chemical mutagens. Combined exposure of wheat seedlings to a gamma radiation dose of 2 kR and to laser radiation with the wave length of 632.8 nm (power density - 20 mVt/cm 2 , exposure - 30 min.) resulted in reducing the chromosomal aberration percentage from 30.5% in the gamma version to 16.3% in the combined treatment version. A radiosensibilizing effect was observed at additional exposure of gamma irradiated wheat seeds to laser light with the wave length of 441.6 nm where chromosomal aberration percentage increased from 22% in the gamma-irradiation version to 31% in the combined treatment version. By laser radiation it is also possible to normalize mitotic cell activity suppressed by gamma irradiation. Additional seedling irradiation with the light of helium-neon laser (632.8 nm) resulted in recovery of mitotic cell activity from 21% to 62% and increasing the average content of DNA per nucleus by 10%. The influence of only laser radiation on plant variability was also studied and it was shown that irradiation of wheat seeds and seedlings with pulsed and continuous laser light of visible spectrum resulted in phenotypically altered forms in M 2 . Their frequencies was dependent upon power density, dose and radiation wave length. Number of altered forms increased in going from long-wave to short-wave spectrum region. In comparing efficiency of different laser types of pulsed and continuous exposure (dose - 180 J/cm 2 ) 2% of altered

Lyman-alpha detector designed for rocket measurements of the direct solar radiation at 121.5 nm

International Nuclear Information System (INIS)

Guineva, V.; Tashev, V.; Witt, G.; Gumbel, J.; Khaplanov, M.

2007-01-01

Rocket measurements of the direct Lyman-alpha radiation penetrating in the atmosphere were planned during the HotPay I rocket experiment, June 2006, Project ASLAF (Attenuation of the Solar Lyman-Alpha Flux), Andoya Rocket Range (ARR), Norway. The basic goal of ASLAF project was the study of the processes in the summer mesosphere and thermosphere (up to 110 km), at high latitudes using the Lyman-alpha measurements. The resonance transition 2 P- 2 S of the atomic hydrogen (Lyman-alpha emission) is the strongest and most conspicuous feature in the solar EUV spectrum. Due to the favourable circumstance, that the Lyman-alpha wavelength (121.5 nm) coincides with a minimum of the O 2 absorption spectrum, the direct Lyman-alpha radiation penetrates well in the mesosphere. The Lyman-alpha radiation is the basic agent of the NO molecules ionization, thus generating the ionospheric D-layer, and of the water vapour photolysis, being one of the main H 2 O loss processes. The Lyman-alpha radiation transfer depends on the resonance scattering from the hydrogen atoms in the atmosphere and on the O 2 absorption. Since the Lyman-alpha extinction in the atmosphere is a measure for the column density of the oxygen molecules, the atmospheric temperature profile can be calculated thereof. The detector of solar Lyman-alpha radiation was manufactured in the Stara Zagora Department of the Solar-Terrestrial Influences Laboratory (STIL). Its basic part is an ionization chamber, filled in with NO. A 60 V power supply is applied to the chamber. The produced photoelectric current from the sensor is fed to a 2-channels amplifier, providing an analogue signal. The characteristics of the Lyman-alpha detector were studied. It passed successfully all tests and the results showed that the instrument could be used in rocket experiments to measure the Lyman-alpha flux. From the measurements of the detector, the Lyman-alpha vertical profile can be obtained. The forthcoming scientific data analysis will

Course for monitored education at distance: 'Introduction to basic aspects of radiation physics in NM'

International Nuclear Information System (INIS)

Lopez, Adlin; Palau, Aley; Petrirena, Gregorio; Cardenas, Ana Ivis

2008-01-01

Full text: Nuclear Medicine became a multimodality speciality, related with a lot of personnel not specialized in NM techniques: who have not training in radiation aspects. These projects try to evaluate the use of specialized multimedia product for a monitored education at distance of personnel who start to be related with Nuclear Medicine Techniques like nurses, surgeons, rheumatologists, etc. The multimedia product included two items: Introduction to Nuclear Medicine Techniques and Basic aspects of radiation physics. Each item contents an audio-visual conference (Power Point) and a charter (PDF): with theoretic aspects, understand verification questions and self-evaluation activities. The product need only a PC compatible with window 98 (or more advanced version), and 130MBy of memory spaced for archive. In order to verify the effectiveness of the distance course, we tested it in 10 students: 1 nurse, 1 radio-pharmacist, 1 cardiologist, 1 neurologist, 6 technologists. After consult and clarify their doubts, a final test was applied in order to check the knowledge acquired. With 100 point of maximum store and 60 point minimum to pass, the test contented 2 types of questions: true or false choice (with 50 aspects to verify 1.5 point/ correct answer) and many correct choices (5 questions, 5 point/correct answer). The average result was 85.6 points/ students: 6 -Excellent (90-100 points) , 3 -Very good (80-89 points) and 1 -Good (70-79 points). The course was polled about the quality of the material and their comprehension degree, asking the student to make suggestions if were needed. The average evaluation was 94 points (91-95 points). The suggestions made were: increase the number of examples and practical sequences, the understand verification questions and include monitored practical exercise. Conclusion: the product can be useful for a monitored education at distance of personnel who start to be related with Nuclear Medicine Techniques. Recommendation: The

Measurement of radiation damage on an epoxy-based optical glue

International Nuclear Information System (INIS)

Huang, H.C.; Peng, K.C.; Sahu, S.K.; Ueno, K.; Chang, Y.H.; Wang, C.H.; Hou, W.S.

1997-01-01

We measured the radiation damage on an optical glue called Eccobond-24, which is a candidate for CsI and BGO crystal calorimeters of the BELLE detector of the KEK B-factory. Absorption spectrophotometry in the range 300-800 nm was used to monitor the radiation damage. The maximum equivalent dose was 1.64 Mrad. The glue shows effects of damage, but is acceptable for the radiation level in the above-mentioned experiment. (orig.)

Human exposure to ultraviolet radiation

International Nuclear Information System (INIS)

Bernhardt, J.H.; Matthes, R.

1987-01-01

Ultraviolet radiation is that part of the electromagnetic spectrum located between the softest ionizing radiation and visible radiation. The lower limit of 100 nm is equivalent to photon energies of 12.4 eV, which corresponds approximately to the limit for the production of ionization in biologically important materials. A historical subdividing of the UV-region takes some of the biological effects into account. In this arrangement the range 400-315 nm, the so-called black light region, is called UV-A. In this wavelength region, fluorescence can be induced in many substances. UV-B covers the range 315-280 nm (the skin erythemal region). Most of the biologically active and potentially harmful UV from the sun reaching the surface of the earth is part of this spectral region. UV-C includes the radiation of wavelengths less than 280 nm (the germicidal region). It should be noted that this classification is somewhat arbitrary, and today it is more usual to evaluate the biological effectiveness of the whole UV-range from 200 to 400 nm

Level Densities and Radiative Strength Functions in 170,171Yb

International Nuclear Information System (INIS)

Agvaanluvsan, U.; Schiller, A.; Becker, J.A.; Berstein, L.A.; Guttormsen, M.; Mitchell, G.E.; Rekstad, J.; Siem, S.; Voinov, A.

2003-01-01

Level densities and radiative strength functions in 171 Yb and 170 Yb nuclei have been measured with the 171 Yb( 3 He, 3 He(prime) γ) 171 Yb and 171 Yb( 3 He, αγ) 170 Yb reactions. A simultaneous determination of the nuclear level density and the radiative strength function was made. The present data adds to and is consistent with previous results for several other rare earth nuclei. The method will be briefly reviewed and the result from the analysis will be presented. The radiative strength function for 171 Yb is compared to previously published work.

Ocean acidification alters the photosynthetic responses of a coccolithophorid to fluctuating ultraviolet and visible radiation.

Science.gov (United States)

Jin, Peng; Gao, Kunshan; Villafañe, Virginia E; Campbell, Douglas A; Helbling, E Walter

2013-08-01

Mixing of seawater subjects phytoplankton to fluctuations in photosynthetically active radiation (400-700 nm) and ultraviolet radiation (UVR; 280-400 nm). These irradiance fluctuations are now superimposed upon ocean acidification and thinning of the upper mixing layer through stratification, which alters mixing regimes. Therefore, we examined the photosynthetic carbon fixation and photochemical performance of a coccolithophore, Gephyrocapsa oceanica, grown under high, future (1,000 μatm) and low, current (390 μatm) CO₂ levels, under regimes of fluctuating irradiances with or without UVR. Under both CO₂ levels, fluctuating irradiances, as compared with constant irradiance, led to lower nonphotochemical quenching and less UVR-induced inhibition of carbon fixation and photosystem II electron transport. The cells grown under high CO₂ showed a lower photosynthetic carbon fixation rate but lower nonphotochemical quenching and less ultraviolet B (280-315 nm)-induced inhibition. Ultraviolet A (315-400 nm) led to less enhancement of the photosynthetic carbon fixation in the high-CO₂-grown cells under fluctuating irradiance. Our data suggest that ocean acidification and fast mixing or fluctuation of solar radiation will act synergistically to lower carbon fixation by G. oceanica, although ocean acidification may decrease ultraviolet B-related photochemical inhibition.

Terrestrial radiation level in selected asphalt plants in Port Harcourt ...

African Journals Online (AJOL)

Terrestrial radiation level in selected asphalt plants in Port Harcourt, Nigeria. ... An environmental radiation survey in asphalt processing plants in Rivers State was been carried out ... Therefore the results show significant radiological risk.

Epidemiological studies in the high and normal level radiation areas of Kerala

International Nuclear Information System (INIS)

Koya, P.K.M.

2012-01-01

High and normal level natural radiation areas of Kerala give unique opportunities to estimate the risk, if any, of chronic low dose exposure by direct epidemiological studies on human beings. Studies in the area are being carried out by Low Level Radiation Research Laboratory of Bhabha Atomic Research Centre in collaboration with Departments of Health and Family Welfare/Social Welfare of the Government of Kerala and local post graduate colleges. To assess the role of chronic low dose exposure in the induction/transmission of chromosomal alterations across generations, hospital based cytogenetic studies on newborns was carried out to estimate and compare the frequency of chromosomal aberrations and karyotypes anomalies in the high (areas with radiation dose of more than 1.50 mGy/year) and normal (areas with radiation dose of 1.50 mR/year or less) level radiation areas. A total of 1,267,788 metaphases from 27,295 (9,64,390 cells from 17,298 newborns of high and 3,03,398 cells from 9,997 newborns of normal level radiation areas) newborns was screened

Radiation levels from computer monitor screens within Benue State ...

African Journals Online (AJOL)

Investigation of possible presence of soft X-ray levels from Computer Screens at distances of 0.5m and 1.0m was carried out within Benue State University, Makurdi, using ten different monitor models. Radiation measurement was carried out using a portable digital radiation meter, INSPECTOR 06250 (SE international Inc.

Low level ionizing radiation and human mortality: multi-regional epidemiological studies

International Nuclear Information System (INIS)

Hickey, R.J.; Bowers, E.J.; Spence, D.E.; Zemel, B.S.; Clelland, A.B.; Clelland, R.C.

1981-01-01

Analyses of relationships involving environmental chemicals, background radiation, and mortality rates for diseases of the heart and several cancer categories are presented. Bivariate correlation coefficients between radiation and mortality rate were significantly negative for cancer of the lung and respiratory organs, cancer of the buccal cavity and pharynx, cancer of the digestive organs and peritoneum, total cancer and diseases of the heart. Only the correlation coefficient between background radiation and leukemia-aleukemia was positive, and that not significantly positive. Initial multivariate statistical studies support the bivariate results in that all significant regression terms that represent background radiation have been negative. Background radiation level was not a significant predictor for leukemia-aleukemia mortality rate when examined without regard to age. This preliminary work suggests that any health effects of background radiation on the diseases studied do not exceed in magnitude those of environmental chemicals. It also suggests that models implying important long-term deleterious effects of low levels of ionizing radiation on humans may be invalid. (author)

Photodissociation of acrylonitrile at 193 nm: A photofragment translational spectroscopy study using synchrotron radiation for product photoionization

International Nuclear Information System (INIS)

Blank, D.A.; Suits, A.G.; Lee, Y.T.; North, S.W.; Hall, G.E.

1998-01-01

We have investigated the photodissociation of acrylonitrile (H 2 CCHCN) at 193 nm using the technique of photofragment translational spectroscopy. The experiments were performed at the Chemical Dynamics Beamline at the Advanced Light Source and used tunable vacuum ultraviolet synchrotron radiation for product photoionization. We have identified four primary dissociation channels including atomic and molecular hydrogen elimination, HCN elimination, and CN elimination. There is significant evidence that all of the dissociation channels occur on the ground electronic surface following internal conversion from the initially optically prepared state. The product translational energy distributions reflect near statistical simple bond rupture for the radical dissociation channels, while substantial recombination barriers mediate the translational energy release for the two molecular elimination channels. Photoionization onsets have provided additional insight into the chemical identities of the products and their internal energy content. copyright 1998 American Institute of Physics

Effect of cross-linkage by gamma radiation in heavy doses to low wear polyethylene in total hip prostheses

International Nuclear Information System (INIS)

Oonishi, H.

1996-01-01

Wear, frictional torque and creep deformity of UHMWPE sockets crosslinked by gamma radiation of 100, 500 and 1000 Mrad in combination with 28 mm alumina heads, were measured using a hip simulator (under constant load 250 kgf with lubrication of saline solution). Hardness and hydrophilic increased and creep deformity decreased as a result of gamma radiation. The initial wear (decrement of the thickness) of the socket with radiation of 0, 100, 500 and 1000 Mrad was, 150 μm, 100 μm, 70 μm and 50 μm, respectively. The time to steady-state wear at 0, 100, 5000 and 1000 Mrad was about 0.15 million, 0.15 million, 0.1 million, and 0.05 million cycles, respectively. The steady-state wear (decrement of the thickness) of the socket without and with radiation was 200 μm/million cycles and less than 20 μm/million cycles, respectively. Rotational torque was under 0.65 Nm in every case. Swing frictional torque at radiation levels of 0, 100, 500 and 1000 MRad were 1.60-2.84 Nm, 3.24-9.02 Nm, 5.23-8.78 Nm, and 2.51-6.79 Nm, respectively. (Author)

Effects of ultraviolet radiation on the lower levels of the planktonic food web in Antarctica

International Nuclear Information System (INIS)

Ferreyra, Gustavo A.; Schloss, Irene; Tosonotto, Gabriela; Calvino, Eduardo; Rodriguez, Silvia; Cantoni, Leonardo; Gonzalez, Oscar; Ulrich, Alejandro; Hernando, Marcelo; Hernandez, Edgardo; Oyarbide, Fabricio

2004-01-01

Full text: Most of the studies that investigated the effects of ultraviolet radiation (UVR, 280-400 NM) on the first levels of the marine food web used experimental approaches (in situ incubations, micro and mesocosms). However, research on the responses to UVR of the micro community in their natural environment is scarce. A time series study including most of the oceanographic parameters described as controlling bacteria and phytoplankton dynamics was carried out (PAR, tidal mixing, turbulent mixing by winds and currents, nutrient stress). In this case, however, the effects of ultraviolet A and B (UVB, 280-320 nm and UVA, 320-400 nm, respectively) were added as forcing parameters. Fieldwork was done in the vicinity of Melchior Station (64 degrees 20' S, 62 degrees 59' W, Observatory Island). It involved the automated measurement of physical variables (currents, tides and meteorological data), as well as discrete sampling of physical (salinity, temperature), chemical (macro nutrients) and biological variables (bacterial and phytoplankton abundance and production, PSI I system, photo protective compounds). Sub-surface sampling (0.5 m depth) was conducted with 5 L Niskin bottles at a fixed station (sampling every 6/12 h centered at local noon during the whole study period), and vertical profiles at 6 fixed depths (0, 5, 10, 20, 30 and 50 m) were done every four days. The whole study lasted for one month, from February 11 to March 12 2002. Average upper mixed layer (UML) was around 20 m and the depth of the euphotic zone (1% of incident radiation) for UVB and UVA was respectively 17 and 32 m, suggesting a strong influence of UVR on cells within the UML. PSII activity showed a significant inverse correlation with UVB, phased with irradiance oscillations. Bacterio plankton and phytoplankton biomass and production of both presented a similar response, but minimum values were lagged by 4-6 h from UVR maxima. Mycosporin like aminoacids (MAA's) were also phased and directly

Comparisons of Air Radiation Model with Shock Tube Measurements

Science.gov (United States)

Bose, Deepak; McCorkle, Evan; Bogdanoff, David W.; Allen, Gary A., Jr.

2009-01-01

This paper presents an assessment of the predictive capability of shock layer radiation model appropriate for NASA s Orion Crew Exploration Vehicle lunar return entry. A detailed set of spectrally resolved radiation intensity comparisons are made with recently conducted tests in the Electric Arc Shock Tube (EAST) facility at NASA Ames Research Center. The spectral range spanned from vacuum ultraviolet wavelength of 115 nm to infrared wavelength of 1400 nm. The analysis is done for 9.5-10.5 km/s shock passing through room temperature synthetic air at 0.2, 0.3 and 0.7 Torr. The comparisons between model and measurements show discrepancies in the level of background continuum radiation and intensities of atomic lines. Impurities in the EAST facility in the form of carbon bearing species are also modeled to estimate the level of contaminants and their impact on the comparisons. The discrepancies, although large is some cases, exhibit order and consistency. A set of tests and analyses improvements are proposed as forward work plan in order to confirm or reject various proposed reasons for the observed discrepancies.

Examining a link between SPEs and ground level radiation

Science.gov (United States)

Overholt, Andrew

2015-01-01

Researchers have previously found a correlation between solar proton events (SPEs) and congenital malformations (CMs). A similar correlation has also been found between long term solar variability and CMs. We examine the ionizing radiation dose from these events as well as the largest events on record to determine whether these events are capable of producing these effects. We show that the total ionizing radiation dose (consisting of neutrons and muons) at ground level is insufficient for production of the observed increases in CM rate under the current paradigm regarding ionizing radiation from muons and neutrons. Current research on the subject shows that our assumptions regarding muonic ionizing radiation may be underestimating their biologic effect. We recommend further experimentation regarding the radiation dose due to muons, as this may prove to be a more substantial contribution to our radiation environment than previously assumed.

Inhibitory effects of ambient levels of solar UV-A and UV-B radiation in growth of cv. New Red Fire lettuce

International Nuclear Information System (INIS)

Krizek, D.T.; Britz, S.J.; Mirecki, R.M.

1998-01-01

The influence of solar UV-A and UV-B radiation at Beltsville, MD, USA, on growth of Lactuca sativa L. (cv. New Red Fire lettuce) was examined during early summer of 1996 and 1997. Plants were grown from seed in plastic window boxes covered with Llumar to exclude UV-A and UV-B, polyester to exclude UV-B, or tefzel (1996) or teflon (1997) to transmit UV-A and UV-B radiation. After 31-34 days, plants grown in the absence of solar UV-B radiation (polyester) had 63 and 57% greater fresh weight and dry weight of tops, respectively, and 57, 72 and 47% greater dry weight of leaves, stems and roots, respectively, as compared to those grown under ambient UV-B (tefzel or teflon). Plants protected from UV-A radiation as well (Llumar) showed an additional 43 and 35% increase, respectively, in fresh and dry weight of tops and a 33 and 33% increase, respectively, in dry weight of leaves and stems, but no difference in root biomass over those grown under polyester. Excluding ambient UV-B (polyester) significantly reduced the UV absorbance of leaf extracts at 270, 300 and 330 nm (presumptive flavonoids) and the concentration of anthocyantins at 550 nm as compared to those of leaf extract from plants grown under ambient UV-A and UV-B. Additional removal of ambient UV-A (Llumar) reduced the concentration of anthocyanins, but had no further effect on UV absorbance at 270, 300 or 330 nm. These findings provide evidence that UV-B radiation is more important than UV-A radiation for flavonoid induction in this red-pigmented lettuce cultivar. Although previous workers have obtained decreases in lettuce yield under enhanced UV-B, this is the first evidence for inhibitory effects of solar UV-A and UV-B radiation on lettuce growth. (au)

Inhibitory effects of ambient levels of solar UV-A and UV-B radiation in growth of cv. New Red Fire lettuce

Energy Technology Data Exchange (ETDEWEB)

Krizek, D.T.; Britz, S.J.; Mirecki, R.M. [Climate Stress Laboratory, Beltsville, MD (United States)

1998-05-01

The influence of solar UV-A and UV-B radiation at Beltsville, MD, USA, on growth of Lactuca sativa L. (cv. New Red Fire lettuce) was examined during early summer of 1996 and 1997. Plants were grown from seed in plastic window boxes covered with Llumar to exclude UV-A and UV-B, polyester to exclude UV-B, or tefzel (1996) or teflon (1997) to transmit UV-A and UV-B radiation. After 31-34 days, plants grown in the absence of solar UV-B radiation (polyester) had 63 and 57% greater fresh weight and dry weight of tops, respectively, and 57, 72 and 47% greater dry weight of leaves, stems and roots, respectively, as compared to those grown under ambient UV-B (tefzel or teflon). Plants protected from UV-A radiation as well (Llumar) showed an additional 43 and 35% increase, respectively, in fresh and dry weight of tops and a 33 and 33% increase, respectively, in dry weight of leaves and stems, but no difference in root biomass over those grown under polyester. Excluding ambient UV-B (polyester) significantly reduced the UV absorbance of leaf extracts at 270, 300 and 330 nm (presumptive flavonoids) and the concentration of anthocyantins at 550 nm as compared to those of leaf extract from plants grown under ambient UV-A and UV-B. Additional removal of ambient UV-A (Llumar) reduced the concentration of anthocyanins, but had no further effect on UV absorbance at 270, 300 or 330 nm. These findings provide evidence that UV-B radiation is more important than UV-A radiation for flavonoid induction in this red-pigmented lettuce cultivar. Although previous workers have obtained decreases in lettuce yield under enhanced UV-B, this is the first evidence for inhibitory effects of solar UV-A and UV-B radiation on lettuce growth. (au) 34 refs.

Health effects of low-level radiation in shipyard workers

International Nuclear Information System (INIS)

Matanoski, G.M.

1991-06-01

The Nuclear Shipyard Workers Study (NSWS) was designed to determine whether there is an excess risk of leukemia or other cancers associated with exposure to low levels of gamma radiation. The study compares the mortality experience of shipyard workers who qualified to work in radiation areas to the mortality of similar workers who hold the same types of jobs but who are not authorized to work in radiation areas. The population consists of workers from six government and two private shipyards

Correlation between endogenous glutathione content and sensitivity of cultured human skin cells to radiation at defined wavelengths in the solar ultraviolet range

International Nuclear Information System (INIS)

Tyrrell, R.M.; Pidoux, M.

1988-01-01

Glutathione depletion of cultured human skin fibroblasts by treatment with buthionine-S.R.-sulfoximine (BSO) sensitises them to solar UV radiation. We now show that there is a close quantitative correlation between cellular glutathione content and sensitivity to radiation at 365 nm. A weaker correlation is observed when cells are depleted of glutathione using diethylmaleimide. Both fibroblasts and epidermal keratinocytes derived from the same foreskin biopsy are sensitised to radiation at 313 nm by glutathione depletion. At low to intermediate fluence levels, 10 mM cysteamine present during irradiation at 302 nm is able to almost completely reverse the sensitising effects of glutathione depletion suggesting that the endogenous thiol protects against radiation at this wavelength by a free radical scavenging mechanism. At 313 nm, the sensitisation is not reversed by cysteamine suggesting that glutathione plays a more specific role in protection against radiation at longer wavelengths. Xeroderma pigmentosum group A fibroblasts (excision deficient) are also sensitised to radiation at 313 and 365 nm by depletion of glutathione. The results provide further evidence that endogenous glutathione is involved in protecting human skin cells against a wide range of solar radiation damage. (author)

Combined radiation damage, annealing, and ageing studies of InGaAsP /InP 1310 nm lasers for the CMS tracker optical links

CERN Document Server

Gill, K; Troska, Jan K; Vasey, F

2002-01-01

A summary is presented of the combined effects of radiation damage, accelerated annealing and accelerated ageing in 1310 nm InGaAsP/InP multi-quantum-well lasers, the type chosen for use in the CMS Tracker optical links. The radiation damage effects are compared for a variety of radiation sources: /sup 60/Co-gamma, 0.8 MeV (average energy) neutrons, 20 MeV (average energy) neutrons and 300 MeV/c pions that represent important parts of the spectrum of particles that will be encountered in the CMS Tracker. The relative damage factors of the various sources are calculated by comparing the laser threshold current increase due to radiation damage giving approximately=0 : 0.12 : 0.53 : 1 for /sup 60/Co-gamma, approximately =0.8 MeV neutrons, approximately=20 MeV neutrons with respect to 300 MeV/c pions. The effects of bias current and temperature on the annealing were measured and, in all cases, the annealing is proportional to log(annealing time). A bias current of 60 mA increases the annealing, in terms of the ti...

Evaluation of radiation protection educational level of professional exposed workers

International Nuclear Information System (INIS)

Marinkovic, O.; Krstev, S.; Jovanovic, S.

2006-01-01

Full text: Serbia and Montenegro legislation concerning with radiation protection was upgrading after publication ICRP- 60 and B.S.S., No.115. Present Law on the Protection against Ionizing Radiation is in force from 1996. Among quite new issues in radiation protection regulations there was article relate to obligatory refresher training. Due to adverse political and economic situation through many years radiation protection regulations were not fulfill completely. The aim of this investigation was to get real view to education level of professional exposed workers. In Serbia and Montenegro the most of ionizing radiation sources are in medical use and the most exposed workers are radiographers and radiologists. The test was passed by 200 radiographers and 50 radiologists. Main groups of questions were: Radiation protection and safety; difference between safety and security; legislation: law and regulations; incidents, accidents and operational failures: recording, learning. Usually, knowledge from school pales. New quantities (as ambient and personal dose equivalent) are mostly unknown. It is easier to understand the real difference between safety and security than to understand linguistic differences. Discussing regulations workers are more interesting in syndicate regulations than radiation protection ones. Operational failures and incidents are hidden. Better to say: nobody dare to speak about them. The results imposed conclusion that regulatory body has to pay more attention to upraise safety culture and radiation protection education level of professional exposed workers. (authors)

Experiments on the interaction of intense femtosecond radiation with dense plasmas. Final report

International Nuclear Information System (INIS)

Rhodes, C.K.

1996-01-01

An upgraded KrF * (248 nm) system producing a pulse energy of ∼ 400 mJ, a pulse width of ∼ 220 fs, and focal intensities above 10 19 W/cm 2 , has been constructed, tested, operated, and used in experimental studies. The spatial morphology of channeled radiation in plasmas has been measured with a spatial resolution of ∼ 30 μm and damage studies of fused silica indicate that femtosecond (200 - 300 fs) 248 nm radiation has a damage limit not exceeding ∼ 50 GW/cm 2 , an unfavorably low level. 2 figs

Knowledge of medical imaging radiation dose and risk among doctors.

Science.gov (United States)

Brown, Nicholas; Jones, Lee

2013-02-01

The growth of computed tomography (CT) and nuclear medicine (NM) scans has revolutionised healthcare but also greatly increased population radiation doses. Overuse of diagnostic radiation is becoming a feature of medical practice, leading to possible unnecessary radiation exposures and lifetime-risks of developing cancer. Doctors across all medical specialties and experience levels were surveyed to determine their knowledge of radiation doses and potential risks associated with some diagnostic imaging. A survey relating to knowledge and understanding of medical imaging radiation was distributed to doctors at 14 major Queensland public hospitals, as well as fellows and trainees in radiology, emergency medicine and general practice. From 608 valid responses, only 17.3% correctly estimated the radiation dose from CT scans and almost 1 in 10 incorrectly believed that CT radiation is not associated with any increased lifetime risk of developing cancer. There is a strong inverse relationship between a clinician's experience and their knowledge of CT radiation dose and risks, even among radiologists. More than a third (35.7%) of doctors incorrectly believed that typical NM imaging either does not use ionising radiation or emits doses equal to or less than a standard chest radiograph. Knowledge of CT and NM radiation doses is poor across all specialties, and there is a significant inverse relationship between experience and awareness of CT dose and risk. Despite having a poor understanding of these concepts, most doctors claim to consider them prior to requesting scans and when discussing potential risks with patients. © 2012 The Authors. Journal of Medical Imaging and Radiation Oncology © 2012 The Royal Australian and New Zealand College of Radiologists.

How much can be learned from populations exposed to low levels of radiation

International Nuclear Information System (INIS)

Gilbert, E.S.

1984-05-01

The assessment of health effects from low-level exposure to radiation is a matter of considerable controversy. Many of the problems in analyzing and interpreting data on populations exposed to low levels of radiation are well illustrated by a current study of the effects on mortality of occupational exposure to radiation at the Hanford plant. The conclusion drawn is that the amount that can be learned from the Hanford population, and other populations exposed to low levels of radiation, is extremely limited. The data are not adequate to determine reliable estimates of risks, or to investigate the appropriateness of various models. Although there are problems in using data from populations exposed at high levels to estimate risks of low level exposure to radiation, the problems in obtaining such estimates directly are even more severe. Thus data from populations such as the Japanese A-bomb survivors and the British ankylosing spondylitis patients must continue to serve as our primary source of information on radiation effects. 27 references, 3 tables

Time-resolved x-ray diffraction studies on the intensity changes of the 5.9 and 5.1 nm actin layer lines from frog skeletal muscle during an isometric tetanus using synchrotron radiation

International Nuclear Information System (INIS)

Wakabayashi, K.; Tanaka, H.; Amemiya, Y.; Fujishima, A.; Kobayashi, T.; Hamanaka, T.; Sugi, H.; Mitsui, T.

1985-01-01

Time-resolved x-ray diffraction studies have been made on the 5.9- and 5.1-nm actin layer lines from frog skeletal muscles during an isometric tetanus at 6 degrees C, using synchrotron radiation. The integrated intensities of these actin layer lines were found to increase during a tetanus by 30-50% for the 5.9-nm reflection and approximately 70% for the 5.1-nm reflection of the resting values. The intensity increase of both reflections was greater than that taking place in the transition from rest to rigor state. The intensity change of the 5.9-nm reflection preceded those of the myosin 42.9-nm off-meridional reflection and of the equatorial reflections, as well as the isometric tension development. The intensity profile of the 5.9-nm layer line during contraction was found to be different from that observed in the rigor state

Laser Shock Processing of 6061-T6 Al alloy with 1064 nm and 532 nm wavelengths

International Nuclear Information System (INIS)

Gomez-Rosas, G.; Rubio-Gonzalez, C.; Ocana, J.L.; Molpeceres, C.; Porro, J.A.; Morales, M.; Casillas, F.J.

2010-01-01

Laser Shock Processing (LSP) has been proposed as a competitive alternative technology to classical treatments for improving fatigue and wear resistance of metals. We present a configuration and results in the LSP concept for metal surface treatments in underwater laser irradiation at 532 nm and 1064 nm. The purpose of the work is to compare the effect of both wavelengths on the same material. A convergent lens is used to deliver 1.2 J/pulse (1064 nm) and 0.9 J/pulse (532 nm) in a 8 ns laser FWHM pulse produced by 10 Hz Q-switched Nd:YAG laser with spots of a 1.5 mm in diameter moving forward along the work piece. A LSP configuration with experimental results using a pulse density of 2500 pulses/cm 2 and 5000 pulses/cm 2 in 6061-T6 aluminum samples are presented. High level compressive residual stresses are produced using both wavelengths. It has been shown that surface residual stress level is comparable to that achieved by conventional shot peening, but with greater depths. This method can be applied to surface treatment of final metal products.

Radiation Dose Contribution To The Worker Health Level At Serpong Area

International Nuclear Information System (INIS)

Yuwono, Indro

2000-01-01

Analysis of internal and external radiation doses received for radiation and non-radiation workers of P2TBDU have been done. In the period of 1997/1998 and 1998/1999 there were no significant increasing level of radiation doses received that was 0.55 mSv and highest received radiation dose was 2.66% from dose limit value. Increasing of healthy difference on the same period was 5.76%. Increasing of healthy difference no cause by increasing of radiation dose received but maybe the food consumption design

Epidemiological studies on the effects of low-level ionizing radiation on cancer risk

International Nuclear Information System (INIS)

Akiba, Suminori

2010-01-01

The health effects of low-level ionizing radiation are yet unclear. As pointed out by Upton in his review (Upton, 1989), low-level ionizing radiation seems to have different biological effects from what high-level radiation has. If so, the hazard identification of ionizing radiation should he conducted separately for low- and high-level ionizing radiation; the hazard identification of low-level radiation is yet to be completed. What makes hazard identification of ionizing radiation difficult, particularly in the case of carcinogenic effect, is the difficulty in distinguishing radiation-induced cancer from other cancers with respect to clinicopathological features and molecular biological characteristics. Actually, it is suspected that radiation-induced carcinogenesis involves mechanisms not specific for radiation, such as oxidative stress. Excess risk per dose in medium-high dose ranges can be extrapolated to a low-dose range if dose-response can be described by the linear-non-threshold model. The cancer risk data of atomic-bomb survivors describes leukemia risk with a linear-quadratic (LQ) model and solid-cancer risk with linear non-threshold (LNT) model. The LQ model for leukemia and the LNT model for solid cancer correspond to the two-hit model and the one-hit model, respectively. Although the one-hit model is an unlikely dose-response for carcinogenesis, there is no convincing epidemiological evidence supporting the LQ model or non-threshold model for solid cancer. It should be pointed out, however, even if the true dose response is non-linear various noises involved in epidemiological data may mask the truth. In this paper, the potential contribution of epidemiological studies on nuclear workers and residents in high background radiation areas will be discussed. (author)

Effect of low doses of ionizing radiation on circulating microparticles levels

International Nuclear Information System (INIS)

Ekhtiar, A.; Al-Massarani, Gh.; Najjar, F.; Aljapawe, A.

2015-01-01

Ionizing radiation is known to cause disruption of cytoskeleton. Cytoskeleton disorganization results in circulating microvesicles (MVs). The aim of this study was to investigate the relationship between the exposure to low-radiation and MVs levels in the peripheral blood of individuals working in radiation technology field.(author)

[Staffing levels in medical radiation physics in radiation therapy in Germany. Summary of a questionnaire].

Science.gov (United States)

Leetz, Hans-Karl; Eipper, Hermann Hans; Gfirtner, Hans; Schneider, Peter; Welker, Klaus

2003-10-01

To get a general idea of the actual staffing level situation in medical radiation physics in 1999 a survey was carried out by the task-group "Personalbedarf" of Deutsche Gesellschaft für Medizinische Physik (DGMP) among all DGMP-members who are active in this field. Main components for equipment and activities are defined in Report 8 and 10 of DGMP for staffing requirements in medical radiation physics. 322 forms were sent out, 173 of them have been evaluated. From the answers regarding equipment and activities numbers for staff are calculated by the methods given in Report 8 and 10 for this spot check target and compared with effective staffing levels. The data of the spot check are then extrapolated on total Germany. The result is a calculated deficit of 865 medical physicists for the whole physics staff, 166 of them in radiation therapy. From the age distribution of DGMP-members and the calculated deficit resulted a training capacity of about 100 medical physicists at all per year (19 in radiation therapy) if the deficit shall be cut back in 10 years.

Determination of radiation levels by neutrons in an accelerator for radiotherapy

International Nuclear Information System (INIS)

Paredes G, L.; Salazar B, M.A.; Genis S, R.

1998-01-01

It was determined the radiation levels by neutrons due to photonuclear reactions (γ, n) which occur in the target, levelling filter, collimators and the small pillow blinding of a medical accelerator Varian Clinac 2100C of 18 MeV, using thermoluminescent dosemeters UD-802AS and US-809AS. The experimental values were presented for the patient level, inside and outside of the radiation field, as well as for the small pillow. (Author)

UV radiation and primary production in the Antarctic waters

Digital Repository Service at National Institute of Oceanography (India)

LokaBharathi, P.A.; Krishnakumari, L.; Bhattathiri, P.M.A.; Chandramohan, D.

at 683 nm), scalar irradiance (photosynthetically active radiation (PAR), computed primary production (pp), diffuse attenuation coefficient, and UVB (308 and 320 nm) and UVA (340 and 380 nm) radiation and ocean temperature all measured as a function...

Resistance of Feather-Associated Bacteria to Intermediate Levels of Ionizing Radiation near Chernobyl.

Science.gov (United States)

Ruiz-González, Mario Xavier; Czirják, Gábor Árpád; Genevaux, Pierre; Møller, Anders Pape; Mousseau, Timothy Alexander; Heeb, Philipp

2016-03-15

Ionizing radiation has been shown to produce negative effects on organisms, although little is known about its ecological and evolutionary effects. As a study model, we isolated bacteria associated with feathers from barn swallows Hirundo rustica from three study areas around Chernobyl differing in background ionizing radiation levels and one control study site in Denmark. Each bacterial community was exposed to four different γ radiation doses ranging from 0.46 to 3.96 kGy to test whether chronic exposure to radiation had selected for resistant bacterial strains. Experimental radiation duration had an increasingly overall negative effect on the survival of all bacterial communities. After exposure to γ radiation, bacteria isolated from the site with intermediate background radiation levels survived better and produced more colonies than the bacterial communities from other study sites with higher or lower background radiation levels. Long-term effects of radiation in natural populations might be an important selective pressure on traits of bacteria that facilitate survival in certain environments. Our findings indicate the importance of further studies to understand the proximate mechanisms acting to buffer the negative effects of ionizing radiation in natural populations.

Low level radiation: how low can you get?

International Nuclear Information System (INIS)

Townsley, M.

1990-01-01

Information stored on the world's largest data bank concerning the health of nuclear industry workers is to be handed over to researchers at Birmingham University by the US Department of Energy. The data bank contains detailed information on 300,000 nuclear employees, going back to the 1940s. Such a large sample size will allow the results of a previous study conducted on workers in the US nuclear industry to be verified. That study was concluded in 1978 and showed that the risk estimates set by the International Commission on Radiological Protection (ICRP) were between 10 and 30 times too low. The current ICRP estimate allows workers up to 50mSv of exposure to low level radiation per year. Risk estimates have been derived from data relating to the atomic bombings of Hiroshima and Nagasaki. However in those cases the radiation doses were relatively high but over a short period. In the nuclear industry the doses are lower but are long term and this may account for the apparent anomalies such as the incidence of leukaemia amongst children whose fathers have worked in the nuclear industry compared with that for the children whose fathers received radiation doses from the atomic bombings. It is expected the study will show that low-level radiation is more damaging than has previously been thought. (author)

LASER RADIATION CHARACTERISTICS (BRIEF COMMUNICATIONS): Conversion of KrCl and XeCl laser radiation to the visible spectral range by stimulated Raman scattering in lead vapor

Science.gov (United States)

Evtushenko, Gennadii S.; Mel'chenko, S. V.; Panchenko, Aleksei N.; Tarasenko, Viktor F.

1990-04-01

Conversion of KrCl and XeCl laser radiation by stimulated Raman scattering was achieved in lead vapor. The KrCl laser radiation was converted into three lines in the visible region at λ = 406, 590, and 723 nm by transitions from both the ground and first excited levels of the lead atom. The conversion efficiency of XeCl laser radiation of low spatial coherence was found to be limited by the activation of a competing nonlinear process.

Studies on nanosecond 532nm and 355nm and ultrafast 515nm and 532nm laser cutting super-hard materials

Science.gov (United States)

Zhang, Jie; Tao, Sha; Wang, Brian; Zhao, Jay

2017-02-01

In this paper, micro-processing of three kinds of super-hard materials of poly-crystal diamond (PCD)/tungsten-carbide (WC), CVD-diamond and cubic boron nitride (CNB) has been systematically studied using nanosecond laser (532nm and 355nm), and ultrafast laser (532nm and 515nm). Our purpose is to investigate a full laser micro-cutting solution to achieve a ready-to-use cutting tool insert (CTI). The results show a clean cut with little burns and recasting at edge. The cutting speed of 2-10mm/min depending on thickness was obtained. The laser ablation process was also studied by varying laser parameters (wavelength, pulse width, pulse energy, repetition rate) and tool path to improve cutting speed. Also, studies on material removal efficiency (MRE) of PCD/WC with 355nm-ns and 515nm-fs laser as a function of laser fluence show that 355nm-ns laser is able to achieve higher MRE for PCD and WC. Thus, ultrafast laser is not necessarily used for superhard material cutting. Instead, post-polishing with ultrafast laser can be used to clean cutting surface and improve smoothness.

Acute effects of low-level laser therapy (660 nm) on oxidative stress levels in diabetic rats with skin wounds.

Science.gov (United States)

Denadai, Amanda Silveira; Aydos, Ricardo Dutra; Silva, Iandara Schettert; Olmedo, Larissa; de Senna Cardoso, Bruno Mendonça; da Silva, Baldomero Antonio Kato; de Carvalho, Paulo de Tarso Camillo

2017-09-01

Laser therapy influences oxidative stress parameters such as the activity of antioxidant enzymes and the production of reactive oxygen species. To analyze the effects of low-level laser therapy on oxidative stress in diabetics rats with skin wounds. Thirty-six animals were divided into 4 groups: NDNI: non-diabetic rats with cutaneous wounds that not received laser therapy; NDI: non-diabetic rats with cutaneous wounds that received laser therapy; DNI: diabetic rats with skin wounds who did not undergo laser therapy; DI: rats with diabetes insipidus and cutaneous wounds and received laser therapy. The animals were treated with LLLT (660 nm, 100 mW, 6 J/cm, spot size 0.028 cm). On the day of killing the animals, tissue-wrapped cutaneous wounds were collected and immediately frozen, centrifuged, and stored to analyze malondialdehyde (MDA) levels. Significant difference was observed within the groups of MDA levels (ANOVA, p = 0.0001). Tukey's post-hoc test showed significantly lower values of MDA in irradiated tissues, both in diabetic and non-diabetic rats. ANOVA of the diabetic group revealed a significant difference (p < 0.01) when all groups, except NDI and DI, were compared. LLLT was effective in decreasing MDA levels in acute surgical wounds in diabetic rats.

Radiation Levels around the LHC

CERN Document Server

Mala, P; Calviani, M; Nordt, A

2013-01-01

This work discuss on the radiation levels measured around the LHC machine during the 2012 operational year. The doses and particle fluences are measured primarily by RadMon detectors – about 300 RadMons are installed around the accelerator – and by thermoluminescent detectors. In addition, BLMs, IG5/PMI ionisation chambers as well as FGCs can be used for corresponding cumulated dose evaluations. The probability of SEE depends directly on the high-energy hadron (HEH) fluence, so this is the main parameter that is calculated based on RadMons counts.

Environmental radiation levels around Nuclear Fuel Complex, Hyderabad during 1981-1988

International Nuclear Information System (INIS)

Mehta, Navnit; Lakshmanan, A.R.; Kathuria, S.P.; Nambi, K.S.V.

1989-01-01

This report presents environmental radiation monitoring results around Nuclear Ffuel Complex (NFC) at Hyderabad for the period, 1981-'88. During 1981-'83 only indoor radiations were monitored at 12 locations in the region of about 15 km. radius around NFC plant. However, during 1984-'88 both indoor and outdoor monitoring was done in a standardised manner at 8 locations. In this routine monitoring programme, environmental thermoluminescent dosimeters were used in quarterly integrating cycles. The average outdoor natural radiation level around NFC during 1984-'88 is found to be 227 ± 34 (σ) mR/y, which is the highest among the various sites in the country where DAE units are located. Such a high level of natural background radiation in and around Hyderabad is due to granitic terrains which normally have significant amounts of primordial radioactivity. The indoor to outdoor radiation ratio is found to be 1.35 ± 0.1 (σ). Application of this ratio on all the available indoor radiation monitoring results of 1981-'88 gives an estimate of 230 ± 26 mR/y as the average outdoor radiation level, and this is in very close agreement with the directly measured value mentioned earlier. The temporal variations seen in the quarterly results of each location have been tested for Normal and Log-Normal distributions and found to yield satisfactory correlations, although the plots reveal slight skewness; the latter however, could not be attributed to the NFC operations. (author). 7 refs., 4 tabs., 12 figs

Laser spectroscopy of the 109.1-nm transition in neutral Cs

International Nuclear Information System (INIS)

Dimiduk, D.P.; Young, J.F.; Harris, S.E.; Pedrotti, K.D.

1986-01-01

Certain core-excited quartet levels in alkali-like atoms and ions, termed quasi-metastable, have slow autoionizing rates and comparable (relatively fast for quartets) VUV radiative rates. This circumstance, desirable for laser transitions, is due to angular momentum and parity selection rules on these quarters and the doublets to which they may couple via the spin-orbit interaction. The 109.1-nm transition is between Cs(5p/sup 5/5d6s)/sup 4/P/sub 5/2/ and Cs(5p/sup 6/5d)/sup 2/D and is a prototype of a class of transitions which originate on quasi-metastable levels. It has been observed in emission from a pulsed hollow-cathode discharge. Here the authors report an experiment using the same discharge to populate the lower level of this transition; tunable VUV radiation, generated by four-wave mixing, is used to make absorption measurements at near Doppler-limited resolution. From these data the authors measure accurately the fine-structure splitting of the transition, estimate the oscillator strength and hyperfine splitting, and thus confirm the identity of the transition. The VUV radiation was generated via a resonant process in Zn vapor and then directed through the pulsed hollow cathode. The scanned VUV was absorbed by the excited Cs(5p/sup 6/5d)/sup 2/D atoms in the discharge. The authors measured separately the excited atom populations via absorption on the 5d-nf transitions, thus measuring the NL product of the lower levels. By varying the discharge current, the absorption was measured as a function of the lower level NL yielding curves of growth for these transitions. Careful study of these curves yielded the oscillator strengths of both components of this transition and an estimate of the hyperfine broadening of the upper level. The measured oscillator strengths agreed well with the authors' calculations using the code RCN/RCG

An action spectrum for UV-B radiation and the rat lens.

Science.gov (United States)

Merriam, J C; Löfgren, S; Michael, R; Söderberg, P; Dillon, J; Zheng, L; Ayala, M

2000-08-01

To determine an action spectrum for UV-B radiation and the rat lens and to show the effect of the atmosphere and the cornea on the action spectrum. One eye of young female rats was exposed to 5-nm bandwidths of UV-B radiation (290, 295, 300, 305, 310, and 315 nm). Light scattering of exposed and nonexposed lenses was measured 1 week after irradiation. A quadratic polynomial was fit to the dose-response curve for each wave band. The dose at each wave band that produced a level of light scattering greater than 95% of the nonexposed lenses was defined as the maximum acceptable dose (MAD). Transmittance of the rat cornea was measured with a fiberoptic spectrophotometer. The times to be exposed to the MAD in Stockholm (59.3 degrees N) and La Palma (28 degrees N) were compared. Significant light scattering was detected after UV-B at 295, 300, 305, 310, and 315 nm. The lens was most sensitive to UV-B at 300 nm. Correcting for corneal transmittance showed that the rat lens is at least as sensitive to UV radiation at 295 nm as at 300 nm. The times to be exposed to the MAD at each wave band were greater in Stockholm than in La Palma, and in both locations the theoretical time to be exposed to the MAD was least at 305 nm. After correcting for corneal transmittance, the biological sensitivity of the rat lens to UV-B is at least as great at 295 nm as at 300 nm. After correcting for transmittance by the atmosphere, UV-B at 305 nm is the most likely wave band to injure the rat lens in both Stockholm and La Palma.

MEDICAL AND ENVIRONMENTAL EFFECTS OF UV RADIATION.

Energy Technology Data Exchange (ETDEWEB)

SUTHERLAND, B.M.

2001-07-26

Organisms living on the earth are exposed to solar radiation, including its ultraviolet (UV) components (for general reviews, the reader is referred to Smith [1] and Young et al. [2]). UV wavelength regions present in sunlight are frequently designated as UVB (290-320 nm) and UVA (320-400 nm). In today's solar spectrum, UVA is the principal UV component, with UVB present at much lower levels. Ozone depletion will increase the levels of UVB reaching the biosphere, but the levels of UVA will not be changed significantly [3]. Because of the high efficiency of UVB in producing damage in biological organisms in the laboratory experiments, it has sometimes been assumed that UVA has little or no adverse biological effects. However, accumulating data [4, 5], including action spectra (efficiency of biological damage as a function of wavelength of radiation; see Section 5) for DNA damage in alfalfa seedlings [6], in human skin [7], and for a variety of plant damages (Caldwell, this volume) indicate that UVA can induce damage in DNA in higher organisms. Thus, understanding the differential effects of UVA and UVB wavebands is essential for estimating the biological consequences of stratospheric ozone depletion.

Absorption spectrum of DNA for wavelengths greater than 300 nm

International Nuclear Information System (INIS)

Sutherland, J.C.; Griffin, K.P.

1981-01-01

Although DNA absorption at wavelengths greater than 300 nm is much weaker than that at shorter wavelengths, this absorption seems to be responsible for much of the biological damage caused by solar radiation of wavelengths less than 320 nm. Accurate measurement of the absorption spectrum of DNA above 300 nm is complicated by turbidity characteristic of concentrated solutions of DNA. We have measured the absorption spectra of DNA from calf thymus, Clostridium perfringens, Escherichia coli, Micrococcus luteus, salmon testis, and human placenta using procedures which separate optical density due to true absorption from that due to turbidity. Above 300 nm, the relative absorption of DNA increases as a function of guanine-cytosine content, presumably because the absorption of guanine is much greater than the absorption of adenine at these wavelengths. This result suggests that the photophysical processes which follow absorption of a long-wavelength photon may, on the average, differ from those induced by shorter-wavelength photons. It may also explain the lower quantum yield for the killing of cells by wavelengths above 300 nm compared to that by shorter wavelengths

Magnetic Nature of Light Transmission through a 5-nm Gap.

Science.gov (United States)

Yang, Hyosim; Kim, Dai-Sik; Kim, Richard H Joon-Yeon; Ahn, Jae Sung; Kang, Taehee; Jeong, Jeeyoon; Lee, Dukhyung

2018-02-09

Slot antennas have been exploited as important building blocks of optical magnetism because their radiations are invoked by the magnetic fields along the axes, as vectorial Babinet principle predicts. However, optical magnetism of a few-nanometer-width slit, for which fascinating applications are found due to the colossal field enhancement but Babinet principle fails due to the nonnegligible thickness, has not been investigated. In this paper, we demonstrated that the magnetic field plays a dominant role in light transmission through a 5-nm slit on a 150-nm-thick gold film. The 5-nm slit was fabricated by atomic layer lithography, and the transmission was investigated for various incident angles by experiment and simulation at 785-nm wavelength. We found that, due to the deep subwavelength gap width, the transmission has the same incident angle dependence as the tangential magnetic field on the metal surface and this magnetic nature of a nanogap holds up to ~100-nm width. Our analysis establishes conditions for nanogap optical magnetism and suggests new possibilities in realizing magnetic-field-driven optical nonlinearities.

Radiation and man - evaluation of biological and environmental low level radiation effects

International Nuclear Information System (INIS)

Riklis, E.

1977-01-01

The harmful effects of acute radiation cannot be resolved by statistical means and require clearer knowledge of mechanisms of action and much wider collection of human experience before any definite sound stand can be taken. Much information has accumulated from animal experiments, and still the interpretations are not always clearcut, but for human experience it is only the occasional accident which can give a direct answer. Some of the phenomena attributed to low dose radiation are summarized. There are regions of radiation exposure about which we have only limited positive knowledge, an all low-dose risk estimates have been based on effects observed at relatively high doses. Much information has been gathered which does not support the severity of former basic principles, especially our knowledge of mechanisms of repair existing in most cells as natural defence against the damages caused by radiation as well as by many chemicals which act as mutagenic and carcinogenic agents. Understanding these mechanism, their scope of action and their availability to a damaged cell and organism will lead towards modification of the acceptable permissible exposures, in some cases towards severity, but in most cases towards leniency and higher values. For the evaluation of the effects of low level low dose-rate radiations, whether external, or from internal deposition of isotopes, only late somatic and genetic effects should be considered. (B.G.)

Experience of water chemistry and radiation levels in Swedish BWRs

International Nuclear Information System (INIS)

Ivars, R.; Elkert, J.

1981-01-01

From the BWR operational experience in Sweden it has been found that the occupational radiation exposures have been comparatively low in an international comparison. One main reason for the favourable conditions is the good water chemistry performance. This paper deals at first with the design considerations of water chemistry and materials selection. Next, the experience of water chemistry and radiation levels are provided. Finally, some methods to further reduce the radiation sources are discussed. (author)

Optical breakdown threshold investigation of 1064 nm laser induced air plasmas

International Nuclear Information System (INIS)

Thiyagarajan, Magesh; Thompson, Shane

2012-01-01

We present the theoretical and experimental measurements and analysis of the optical breakdown threshold for dry air by 1064 nm infrared laser radiation and the significance of the multiphoton and collisional cascade ionization process on the breakdown threshold measurements over pressures range from 10 to 2000 Torr. Theoretical estimates of the breakdown threshold laser intensities and electric fields are obtained using two distinct theories namely multiphoton and collisional cascade ionization theories. The theoretical estimates are validated by experimental measurements and analysis of laser induced breakdown processes in dry air at a wavelength of 1064 nm by focusing 450 mJ max, 6 ns, 75 MW max high-power 1064 nm IR laser radiation onto a 20 μm radius spot size that produces laser intensities up to 3 - 6 TW/cm 2 , sufficient for air ionization over the pressures of interest ranging from 10 to 2000 Torr. Analysis of the measured breakdown threshold laser intensities and electric fields are carried out in relation with classical and quantum theoretical ionization processes, operating pressures. Comparative analysis of the laser air breakdown results at 1064 nm with corresponding results of a shorter laser wavelength (193 nm) [M. Thiyagarajan and J. E. Scharer, IEEE Trans. Plasma Sci. 36, 2512 (2008)] and a longer microwave wavelength (10 8 nm) [A. D. MacDonald, Microwave Breakdown in Gases (Wiley, New York, 1966)]. A universal scaling analysis of the breakdown threshold measurements provided a direct comparison of breakdown threshold values over a wide range of frequencies ranging from microwave to ultraviolet frequencies. Comparison of 1064 nm laser induced effective field intensities for air breakdown measurements with data calculated based on the collisional cascade and multiphoton breakdown theories is used successfully to determine the scaled collisional microwave portion. The measured breakdown threshold of 1064 nm laser intensities are then scaled to

Theoretical search for optimal pump parameters for observing spontaneous radiation amplification on the λ=41.8-nm transition of Xe IX in plasma

International Nuclear Information System (INIS)

Ivanova, E P; Ivanov, Arkadii L

2004-01-01

Based on a collisional-radiative model, an atomic-kinetic calculation of the gains on the 41.8-nm transitions of Pd-like xenon was performed for the plasma produced due to the interaction of a femtosecond laser pulse with gaseous xenon. The gains g(z,τ) averaged over the spatial and temporal coordinates were compared with the known gains which had been measured experimentally in Xe 8+ . The amplification was shown to occur under the conditions of ionisation of the working ions, and the time of output radiation saturation depends on the time of Xe 8+ transformation to higher-ionised ions. Our theoretical investigation enables determining the optimal pump parameters, at which the product of the gain g by the active medium length L is about 20, which exceeds the experimental gL value. (active media)

Measurement of Background Gamma Radiation Levels at Two ...

African Journals Online (AJOL)

MICHAEL

ABSTRACT: An in-situ measurement of the background radiation level was carried out at the vicinity of three ... Soil contains small quantities of radioactive elements along with their progeny. .... assessment for soil samples from Kestanbol.

Low level radiation testing of micro-electronic components. Pt. 1

International Nuclear Information System (INIS)

Farren, J.; Stephen, J.H.; Mapper, D.; Sanderson, T.K.; Hardman, M.

1984-05-01

A review of the existing literature has been carried out, dealing with the current technology relating to low level radiation testing of microelectronic devices, as used in space satellite systems. After consideration of the space radiation environment, the general effects of cosmic radiation on MOSFET structures and other MOS devices have been assessed. The important aspect of annealing phenomena in relation to gamma-ray induced damage has also been reviewed in detail. The experimental and theoretical aspects of radiation testing have been assessed, with particular reference to the Harwell LORAD low level irradiation test facility. In addition, a review of modern dosimetry methods has been carried out, with specific regard to the problems of accurately measuring low radiation fields (1 to 10 R/hour) over periods of many months. Finally, a detailed account of the proposed experimental programme to be carried out in the LORAD facility is presented, and aspects of the experimental set-up discussed. The particular types of test circuits to be studied are dealt with, and full consideration is given to the various CMOS memory devices of special interest in the ESA space satellite programme. (author)

Advances in 750 nm VECSELs (Conference Presentation)

Science.gov (United States)

Saarinen, Esa J.; Ranta, Sanna; Lyytikäinen, Jari; Saarela, Antti; Sirbu, Alexei; Iakovlev, Vladimir; Kapon, Eli; Guina, Mircea

2017-03-01

Lasers operating in the transmission window of tissue at wavelengths between 700 and 800 nm are needed in numerous medical and biomedical applications, including photodynamic therapy and fluorescence microscopy. However, the performance of diode lasers in this spectral range is limited by the lack of appropriate compound semiconductors. Here, we review our recent research on 750 nm VECSELs. Two approaches to reaching the 750 nm wavelength will be discussed. The first approach relies on intra-cavity frequency doubling a wafer-fused 1500 nm VECSEL. The VECSEL gain chip comprises a GaAs-based DBR and an InP-based gain section, which allows for optical pumping with low-cost commercial diodes at 980 nm. With this scheme we have achieved watt-level output powers and tuning of the laser wavelength over a 40 nm band at around 750 nm. The second approach is direct emission at 750 nm using the AlGaAs/GaAs material system. In this approach visible wavelengths are required for optical pumping. However, the consequent higher costs compared to pumping at 980 nm are mitigated by the more compact laser setup and prospects of doubling the frequency to the ultraviolet range.

Doses of low level ionizing radiation; a misunderstood risk, however unavoidable

International Nuclear Information System (INIS)

Nicolli, D.

1988-01-01

The treatment given by international organizations and associations to the problems of radiation exposures, and the recommendations and norms for calculating risks of low level radiation are analysed. It is shown that there are not zero risks for nuclear energy, and emphasis is given to the risks of natural radiation from environment. (M.C.K.) [pt

Trends in nanosecond melanosome microcavitation up to 1540 nm

Science.gov (United States)

Schmidt, Morgan S.; Kennedy, Paul K.; Noojin, Gary D.; Vincelette, Rebecca L.; Thomas, Robert J.; Rockwell, Benjamin A.

2015-09-01

Thresholds for microcavitation of bovine and porcine melanosomes were previously reported, using single nanosecond (ns) laser pulses in the visible (532 nm) and the near-infrared (NIR) from 1000 to 1319 nm. Here, we report average radiant exposure thresholds for bovine melanosome microcavitation at additional NIR wavelengths up to 1540 nm, which range from ˜0.159 J/cm2 at 800 nm to 4.5 J/cm2 at 1540 nm. Melanosome absorption coefficients were also estimated, and decreased with increasing wavelength. These values were compared to retinal pigment epithelium coefficients, and to water absorption, over the same wavelength range. Corneal total intraocular energy retinal damage threshold values were estimated and compared to the previous (2007) and recently changed (2014) maximum permissible exposure (MPE) safe levels. Results provide additional data that support the recent changes to the MPE levels, as well as the first microcavitation data at 1540 nm, a wavelength for which melanosome microcavitation may be an ns-pulse skin damage mechanism.

Irradiation behavior of developed radiation resistance optical-fibers and observed optical radiation from their SiO2 cores under reactor irradiation

International Nuclear Information System (INIS)

Shikama, Tatsuo; Narui, Minoru; Kayano, Hideo; Kakuta, Tsunemi; Sagawa, Tsutomu; Sanada, Kazuo; Shamoto, Naoki; Uramoto, Toshimasa.

1994-01-01

Two kinds of optical fibers were irradiated in a fission reactor, JMTR(Japan Materials Testing Reactor), up to a 1.55x10 19 n/cm 2 fast neutron fluence and a 3.3x10 9 Gy ionizing dose at 370K. Optical transmission spectra were measured in the wavelength range of 450-1750nm, in-situ. Growth of strong optical absorption bands were observed in the range of wavelength shorter than 750nm. In the meantime, the fibers showed good radiation-resistance in the range of wavelength longer than 750nm. Optical radiations were observed from SiO 2 optical fibers under irradiation. A major part of the observed optical radiations is thought to be composed of broad optical radiation in the whole wavelength range studied in the present experiment. This broad optical radiation will be generated by the process of so-called Cerenkov radiation. Also, a sharp optical radiation peak was found at 1270nm on a F-doped fiber. This peak is thought to relate with doped Fluorine ions and ionizing gamma-ray irradiation. (author)

Ultraviolet-B radiation influences the abundance and distribution of phylloplane fungi on pedunculate oak (Quercus robur)

International Nuclear Information System (INIS)

Newsham, K.K.; Low, M.N.R.; McLeod, A.R.; Greenslade, P.D.; Emmett, B.A.

1997-01-01

The effects of u.v.-B radiation (280-315 nm) on the fungi occurring on the lammas leaves of pedunculate oak (Quercus robur L.) were examined using saplings that were exposed at an outdoor facility to supplemental levels of u.v.-B radiation under treatment arrays of cellulose diacetate-filtered fluorescent lamps, which also produce u.v.-A radiation (315-400 nm). Saplings were also exposed to u.v.-A radiation alone under control arrays of polyester-filtered lamps, and to ambient levels of solar radiation under arrays of unenergized lamps. The u.v.-B treatment corresponded to a 30% elevation above the ambient level of erythemally-weighted u.v.-B radiation. The fungi were examined weekly over a 4-month-period in summer and autumn 1995 using two techniques, the spore fall and leaf impression methods, which differentiated between those fungi occurring on the upper (adaxial) and lower (abaxial) surfaces of the leaves. The abundances of Aureobasidium pullulans (De Bary) Arnaud and Sporobolomyces roseus Kluy. et van Niel, two leaf yeasts which had adaxial:abaxial ratios of < 1 under ambient levels of u.v.-B radiation, were negatively correlated with increasing ambient levels of u.v.-B radiation and were significantly reduced on adaxial leaf surfaces by supplemental levels of u.v.-B. There were few effects of supplemental u.v.-B radiation on the abundances of these yeasts on abaxial leaf surfaces. The abundances of the dematiaceous hyphomycetes, Cladosporium spp. and Epicoccum nigrum Link., species with adaxial:abaxial ratios of ⩾ 1 under ambient levels of u.v.-B radiation, were not correlated with ambient levels of u.v.-B radiation, nor were they usually affected on either leaf surface by supplemental u.v.-B radiation. Alternaria spp. and Microdochium nivale (Fr.) Samuels & Hallet showed consistent responses on adaxial leaf surfaces to u.v.-A radiation applied under control and treatment arrays. Our results suggest that current levels of shortwave radiation already

Induction of heat shock-like proteins in Vigna sinensis seedlings growing under ultraviolet-B (280-320 nm) enhanced radiation

International Nuclear Information System (INIS)

Nedunchezhian, N.; Annamalainathan, K.; Kulandaivelu, G.

1992-01-01

The effect of ultraviolet-B (UV-B) enhanced fluorescent radiation on protein profile and protein synthesis has been investigated in Vigna sinensis L. cv. Walp seedlings growing at various temperatures. In seedlings growing at 30°C, UV-B radiation decreased the level of several proteins as seen in Coomassie brilliant blue stained gel. However, fluorography of the same gel indicates induction of three sets of proteins in the range of 70. 53 and 16 k Da. Such induction under UV-B enhanced radiation resembled that found after heat shock treatments. In seedlings at 10 and 20°C, induction of such proteins varied both qualitatively and quantitatively. At 40°C. UV-B enhanced radiation caused a cumulative effect with temperature. Strong induction of specific proteins by UV-B radiation in seedlings growing under normal temperature indicates a possible protective role

Estimation of natural radiation background level and population dose in China

International Nuclear Information System (INIS)

Pan Ziqiang

1992-01-01

The authors describe in general the natural radiation background level in China, and based on available data present an estimated annual effective dose equivalent of the population to natural radiation that is some 2.3 mSv, of which about 0.54 mSv is from original γ radiation and about 0.8 mSv from radon and its short-lived daughters

Effect of sublethal levels of ionizing radiation on a predator-prey interaction

International Nuclear Information System (INIS)

Chee, P.C.

1976-01-01

The predator-prey interaction studied was that between the largemouth bass (Micropterus salmoides) and the fathead minnow (Pimephales promelas) in an artificial test environment. Experiments were first conducted to determine the 50% lethal dose at 30 days of the minnow. Three different dose rates were used to test the effect of dose rate on the 50% lethal dose value. After the 50% lethal dose was determined the predator-prey interaction experiment was conducted using 30% of the 50% lethal dose as the highest radiation dose, this dose being considered the upper limit to sublethal radiation levels. A 4 x 4 Latin square design was chosen for the experiment, with four treatment levels (control plus three radiation levels) and four replicates. In each test 10 prey minnow were offered to one predator bass and the number of prey left after 14 days was the parameter of interest. A predator-prey interaction experiment using a single high level of radiation and two types of controls as conducted to ascertain the ability of the test environment to detect changes in the predator-prey interaction. The two types of controls were irradiated prey not exposed to predation and non-irradiated prey exposed to predation. An experiment was also conducted to test the correlation between the physical activity patterns of minnow and different doses of radiation. At a dose rate of 37.8 rad/min the 50% lethal dose at 30 days for minnow was found to be 2650 rad. It was found that dose rate had a strong influence on the 50% lethal dose. In the predator-prey interaction test it was found that the 14-day survival rate of prey was unaffected by sublethal levels of ionizing radiation. No significant correlation was detected between the physical activity patterns of minnow and radiation dose

Serum testosterone levels after external beam radiation for clinically localized prostate cancer

International Nuclear Information System (INIS)

Zagars, Gunar K.; Pollack, Alan

1997-01-01

Purpose: To determine whether serum total testosterone levels change after external beam radiation therapy for localized prostate cancer. Methods and Materials: Eighty-five men with clinically localized prostate cancer (T1-T3, N0/NX, M0) who underwent external beam radiation therapy without androgen ablation had pretreatment and 3-month posttreatment total serum testosterone levels determined by radioimmunoassay. Scattered doses to the testicles were measured with thermoluminescent dosimetry in 10 men. Results: Pretreatment serum testosterone levels ranged from 185 to 783 ng/dl, with a mean of 400 ng/dl and a median of 390 ng/dl. The coefficient of variation was 30%. Postradiation 3-month testosterone levels ranged from 163 ng/dl to 796 ng/dl, with mean and median values of 356 ng/dl and 327 ng/ml, respectively. The coefficient of variation was 34%. The 3-month value was significantly lower than the pretreatment value (Wilcoxon paired p = 0.0001). The mean absolute fall was 94 ng/dl and the mean percentage fall was 9%. Although the fall in testosterone level was statistically significant, the difference was very small quantitatively. In contrast, serum prostate-specific antigen levels fell dramatically by 3 months after radiation. Testicular scattered doses ranged from 1.84 to 2.42 Gy, with a mean of 2.07 Gy for a prostatic tumor dose of 68 Gy. Conclusions: Although significant, the fall in serum testosterone level after radiation for localized prostate cancer was small and likely of no pathophysiologic consequence. It is unlikely that scattered testicular radiation plays any significant role in the genesis of this change in testosterone level, which most likely occurs as a nonspecific stress response

Environmental radiation level, radiation anxiety, and psychological distress of non-evacuee residents in Fukushima five years after the Great East Japan Earthquake: Multilevel analyses

Directory of Open Access Journals (Sweden)

Maiko Fukasawa

2017-12-01

Full Text Available The present study aimed to clarify the associations among radiation exposure or psychological exposure to the Fukushima nuclear power plant accident (i.e., fear/anxiety immediately after the accident, current radiation anxiety, and psychological distress among non-evacuee community residents in Fukushima five years after the Great East Japan Earthquake, which occurred in March 2011. A questionnaire survey was administered to a random sample of non-evacuee community residents from 49 municipalities of Fukushima prefecture from February to April 2016, and data from 1684 respondents (34.4% were analyzed. Environmental radiation levels at the time of the accident were ascertained from survey meter data, while environmental radiation levels at the time of the survey were ascertained from monitoring post data. In the questionnaire, immediate fear/anxiety after the accident, current radiation anxiety, and psychological distress were measured using a single-item question, a 7-item scale, and K6, respectively. Multilevel linear or logistic regression models were applied to analyze the determinants of radiation anxiety and psychological distress. The findings showed that environmental radiation levels at the time of the survey were more strongly associated with radiation anxiety than radiation levels immediately after the accident. Disaster-related experiences, such as direct damage, disaster-related family stress, and fear/anxiety after the accident, and demographic characteristics (e.g., younger age, being married, low socioeconomic status were significantly associated with radiation anxiety. Environmental radiation levels at the time of the accident or survey were not significantly associated with psychological distress. Radiation anxiety largely mediated the association between fear/anxiety after the accident and psychological distress. In addition to environmental radiation levels, respondents’ radiation anxiety was affected by multiple factors

Investigation on the acceptance level of radiation exposure. Comparison of Chinese and Japanese

International Nuclear Information System (INIS)

Wu, Jin; Katoh, Kazuaki

1999-01-01

Safety standards must be determined with the contract between a society and the person concerned, i.e. the agreement in a social community. Individual understandings on the (ionizing) radiation should be proper and uniform as far as possible, just in the case. The individual acceptable radiation dose level of a constituent of a community is one of the key roles for radiation managements and also coping with radiofobia (persons who have hatred and/or allergic syndromes for the radiation). The authors have obtained information by means of questionnaires on the acceptable dose levels of the radiation for 2 groups in a community, the one is a medical science group and the other is a science-technology group in both countries, China and Japan. The annual natural radiation dose etc. are described with inquiries to preclude meaningless responses. The levels of the acceptable radiation dose are different in individuals and show wide distributions. The gap between the two acceptable dose levels for a person is narrow, i.e. the one is the minimum radiation dose that a person rejects with dread and the other is the maximum dose that a person does not have any anxiety. The Japanese science-technology group shows the significant higher dose than that of the Chinese science-technology group. The Chinese medical science group shows the significant higher dose than that of the Chinese science-technology group. The Japanese medical science group does not show the statistically significant difference from the Japanese science-technology group. A perception for the radiation exposure and safety is unexpectedly scattered from person to person even though among the high-level intellectual groups mentioned above. There is no difference on this scattering between the Japan and China. (Y. Tanaka)

Measurement and evaluation of the external radiation level at reactor Kartini

International Nuclear Information System (INIS)

Atok Suhartanto; Suparno

2013-01-01

Measurement and evaluation of external radiation level at reactor Kartini in 2012 has been done. The purpose of this activity is to know the external radiation level as a result of the radioactive or radiation source usage, toward the operational of limit condition. The measurement is using survey meter Inspector 11086, factor of calibration 0.991 mR/h, at 9 locations is: Control room area, Thermal column facilities, Demineralizer, Beamport radiography facilities, bulk shielding Deck, Subcritical facilities, Reactor hall, Deck reactor and on the surface of reactor water tank . The highest room average measurement result in 9 working areas for 12 months continuously are at the reactor tank location is between 13.05±1.09 (xlO -2 mSv/hour) to 16.80±1.40 (x10 -2 mSv/hour), and the lowest measurement result in 1 location (control room) is 0.02±0.005 (x10 -2 mSv/hour) to 0.035±0.009 (x10 -2 mSv/hour). The Kartini reactor is involved in the control area which has potentially contaminated and has radiation exposure at the level of 6 mSv/year. Radiation Protection Officer that work in interval will received radiation exposure dosage of 8.4 mSv/year. This dosage is still below the Below Dosage Value which is recommended by, BAPETEN decree No, 4, 2013 about Protection and Radiation Safety in Nuclear Energy Application at 20 mSv/year. The result of the evaluation above shows that the external radiation which occurred in each area is still below the operational of limit condition that is written on the Kartini reactor safety analysis report, on document number: C7/05/B2/LAK/2010, revision 7. So that the workplace is safe for work monitored. (author)

Ambient radiation levels in positron emission tomography/computed tomography (PET/CT) imaging center

Energy Technology Data Exchange (ETDEWEB)

Santana, Priscila do Carmo; Oliveira, Paulo Marcio Campos de; Mamede, Marcelo; Silveira, Mariana de Castro; Aguiar, Polyanna; Real, Raphaela Vila, E-mail: pridili@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Silva, Teogenes Augusto da [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2015-01-15

Objective: to evaluate the level of ambient radiation in a PET/CT center. Materials and methods: previously selected and calibrated TLD-100H thermoluminescent dosimeters were utilized to measure room radiation levels. During 32 days, the detectors were placed in several strategically selected points inside the PET/CT center and in adjacent buildings. After the exposure period the dosimeters were collected and processed to determine the radiation level. Results: in none of the points selected for measurements the values exceeded the radiation dose threshold for controlled area (5 mSv/ year) or free area (0.5 mSv/year) as recommended by the Brazilian regulations. Conclusion: in the present study the authors demonstrated that the whole shielding system is appropriate and, consequently, the workers are exposed to doses below the threshold established by Brazilian standards, provided the radiation protection standards are followed. (author)

A monolithic 180 nm CMOS dosimeter for In Vivo Dosimetry medical application

International Nuclear Information System (INIS)

Villani, E.G.; Crepaldi, M.; DeMarchi, D.; Gabrielli, A.; Khan, A.; Pikhay, E.; Roizin, Y.; Rosenfeld, A.; Zhang, Z.

2014-01-01

The design and development of a monolithic system-on-chip dosimeter fabricated in a standard 180 nm CMOS technology is described. The device is intended for real time In Vivo measurement of dose of radiation during radiotherapy sessions. Owing to its proposed small size, of approximately 1 mm 3 , such solution could be made in-body implantable and, as such, provide a much-enhanced high-resolution, real-time dose measurement for quality assurance in radiation therapy. The device transmits the related information on dose of radiation wirelessly to an external receiver operating in the MICS band. The various phases of this two years project, started in 2011, including the design and development of radiation sensors and integrated RF to perform the readout, will be described. - Highlights: • A novel monolithic CMOS dosimeter of size of 1 mm 3 has been proposed. • Three different fabrications using a CMOS 180 nm technology have been carried out. • Radiation tests results showed a sensitivity of 1 cGy with accuracy better than 3%. • Preliminary RF tests showed that an RF signal is detectable in free air

Radiation levels in eastern Europe

International Nuclear Information System (INIS)

Webb, G.A.M.; Simmonds, J.R.; Wilkins, B.T.

1986-01-01

Immediately after news of the accident at Chernobyl became available on 28 April, the National Radiological Protection Board (NRPB) was asked by the UK Foreign and Commonwealth Office (FCO) for an appraisal of the radiation situation on the basis of which advice would be given to embassy staff, residents in affected countries and prospective travellers. The first Swedish measurements, external gamma dose rates and, later, concentrations of atmospheric and ground radioactivity, were used to estimate the quantity of radioactivity released by means of NRPB's accident consequence code (1), MARC. Our first predictions of 29 April indicated a substantial release of the order of 10 17 - 10 18 Bq, which was expected to lead to tens of early radiation-induced deaths in the area around the site. On the basis of NRPB's recommended Emergency Reference Levels (ERL's), it was thought that there would be a need for evacuation out to 20 to 30 km and for temporary food restrictions out to a few hundred kilometres from the site. FCO accordingly decided to evacuate students from Kiev and Minsk and to advise people not to travel to the western Soviet Union or to north-east Poland unless absolutely necessary

Diode-pumped continuous-wave eye-safe Nd:YAG laser at 1415 nm.

Science.gov (United States)

Lee, Hee Chul; Byeon, Sung Ug; Lukashev, Alexei

2012-04-01

We describe the output performance of the 1415 nm emission in Nd:YAG in a plane-concave cavity under traditional pumping into the 4F5/2 level (808 nm) and direct in-band pumping into the 4F3/2 level (885 nm). An end-pumped Nd:YAG laser yielded maximum cw output power of 6.3 W and 4.2 W at 885 nm and 808 nm laser diode (LD) pumping, respectively. To the best of our knowledge, this is the highest output power of a LD-pumped 1415 nm laser.

Radiative lifetimes of the 2s2p2(4P) metastable levels of N III

Science.gov (United States)

Fang, Z.; Kwong, Victor H. S.; Parkinson, W. H.

1993-01-01

The radiative decay rates of N III 175 nm intersystem lines were measured in the laboratory by recording the time dependence of photon intensities emitted as the 2s2p2(4P) metastable term of N(2+) ions decay to the 2s22p(2P0) ground term. A cylindrical radio frequency ion trap was used to store the electron impact-produced N(2+) ions. The radiative decay signals were analyzed by multiexponential least-squares fits to the data. The measured radiative decay rates to the ground term are 1019(+/- 64)/s for 4P sub 1/2, 74.5(+/- 5.4)/s for 4P sub 3/2, and 308( +/- 22)/s for 4P sub 5/2. Comparisons of the measured values with theoretical values are presented.

An overview of radiation protection at national level in Greece

International Nuclear Information System (INIS)

Dimitriou, P.A.

1997-01-01

The Greek radiation protection Regulations were revised extensively and harmonized with the relevant Euratom Directives in 1991, covering almost all applications of ionizing radiation. According to the low in force, Greek Atomic Energy Commission (GAEC) is the regulatory and competent authority on radiation protection matters. Among others is responsible: for evaluating the environmental radiation, for introducing emergency plans to responsible Ministries to cope with radiation accidents or increased radioactivity levels, for issuing safety regulation concerning the operation employing ionizing radiation, performing inceptions to all installations or laboratories where radioisotopes or radiation producing machines are employed including all medical applications and issuing the certificate of compliance with the radiation protection regulations. GAEC is the governmental licensing authority for import, export, possession, use, transport and disposal of radioactive materials including fissile materials, and is also responsible for providing training and education to scientists and technical personnel on radiation protection and operates a two years postgraduate course in Medical radiation Physics in collaboration with three Greek Universities, leading to an M Sc degree.The achievements, initiatives and perceptivities of GAEC in the fields of its responsibility are discussed. Statistical data concerning the application of ionising radiation in Greece during the last five years are also presented (author)

Low-level radiation: a high-level concern

International Nuclear Information System (INIS)

Holden, C.

1979-01-01

The role of DOE in radiation health effects research is discussed. The possibility of conflict of interest is presented. The Mancuso episode is cited as evidence. The roles of several agencies (EPA, NRC, and OSHA) in establishing safe limits of radiation exposure are discussed

Time course of cerebellar catalase levels after neonatal ionizing radiations

International Nuclear Information System (INIS)

Di Meglio, A.; Caceres, L.; Zieher, L.M.; Guelman, L.R.

2005-01-01

Full text: Reactive oxygen species are physiologically generated as a consequence of aerobic respiration, but this generation is increased in response to external stimuli, including ionizing radiation. The central nervous system (CNS) is vulnerable to oxidative stress due to its high oxygen consumption rate, its high level of polyunsaturated fatty acids and low levels of antioxidant defences. An important compound of this defence system is the antioxidant enzyme catalase, an heme protein that removes hydrogen peroxide from the cell by catalyzing its conversion to water. The aim of the present work was to study if catalase is susceptible to oxidative stress generated by ionizing radiation on the cerebellum. Neonatal rats were irradiated with 5 Gy of X rays and the levels of catalase were measured at 15, 30 and 60 days of age. Results show that there is a decrease in the activity of catalase in irradiated cerebellum at 15 (% respect the control, 65.6 ± 14.8), 30 (51.35± 5.8%), and 60 days (9.3 ± 0.34%). Catalase activity at 15 and 30 days has shown to be positively correlated with the radiation-induced decrease in tissue's weight, while at 60 days there is an extra decrease. It would be suggested that, at long term, radiation exposure might induce, in addition to cerebellar atrophy, the oxidation of the radiosensitive heme group of the enzyme, leading to its inactivation. In conclusion, the antioxidant enzyme catalase has shown to be especially sensitive to ionizing radiation. (author)

Effect of UV Radiation by Projectors on 3D Printing

Directory of Open Access Journals (Sweden)

Kovalenko Iaroslav

2017-01-01

Full Text Available Polymers that solidify under light radiation are commonly used in digital light processing (DLP 3D printing. A wide range of photopolymers use photoinitiators that react to radiation in range of ultraviolet (UV wavelength. In the present study we provided measurement of radiant fluence in the UV wavelength range from 280 nm to 400 nm for two data projectors and compared effect of radiation on quality of 3D printing. One projector is commonly used DLP projector with high energy lamp. Second one is an industrial projector, in which RGB light emitting diodes (LEDs are replaced by UV LEDs with wattage at the level of 3.6 % of the first one. Achieved data confirmed uneven distribution of radiant energy on illuminated area. These results validate, that undesired heating light causes internal stress inside built models that causes defects in final products.

CALIPSO lidar calibration at 532 nm: version 4 nighttime algorithm

Science.gov (United States)

Kar, Jayanta; Vaughan, Mark A.; Lee, Kam-Pui; Tackett, Jason L.; Avery, Melody A.; Garnier, Anne; Getzewich, Brian J.; Hunt, William H.; Josset, Damien; Liu, Zhaoyan; Lucker, Patricia L.; Magill, Brian; Omar, Ali H.; Pelon, Jacques; Rogers, Raymond R.; Toth, Travis D.; Trepte, Charles R.; Vernier, Jean-Paul; Winker, David M.; Young, Stuart A.

2018-03-01

Data products from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on board Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) were recently updated following the implementation of new (version 4) calibration algorithms for all of the Level 1 attenuated backscatter measurements. In this work we present the motivation for and the implementation of the version 4 nighttime 532 nm parallel channel calibration. The nighttime 532 nm calibration is the most fundamental calibration of CALIOP data, since all of CALIOP's other radiometric calibration procedures - i.e., the 532 nm daytime calibration and the 1064 nm calibrations during both nighttime and daytime - depend either directly or indirectly on the 532 nm nighttime calibration. The accuracy of the 532 nm nighttime calibration has been significantly improved by raising the molecular normalization altitude from 30-34 km to the upper possible signal acquisition range of 36-39 km to substantially reduce stratospheric aerosol contamination. Due to the greatly reduced molecular number density and consequently reduced signal-to-noise ratio (SNR) at these higher altitudes, the signal is now averaged over a larger number of samples using data from multiple adjacent granules. Additionally, an enhanced strategy for filtering the radiation-induced noise from high-energy particles was adopted. Further, the meteorological model used in the earlier versions has been replaced by the improved Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2), model. An aerosol scattering ratio of 1.01 ± 0.01 is now explicitly used for the calibration altitude. These modifications lead to globally revised calibration coefficients which are, on average, 2-3 % lower than in previous data releases. Further, the new calibration procedure is shown to eliminate biases at high altitudes that were present in earlier versions and consequently leads to an improved representation of

Ambient radiation levels in positron emission tomography/computed tomography (PET/CT) imaging center

Science.gov (United States)

Santana, Priscila do Carmo; de Oliveira, Paulo Marcio Campos; Mamede, Marcelo; Silveira, Mariana de Castro; Aguiar, Polyanna; Real, Raphaela Vila; da Silva, Teógenes Augusto

2015-01-01

Objective To evaluate the level of ambient radiation in a PET/CT center. Materials and Methods Previously selected and calibrated TLD-100H thermoluminescent dosimeters were utilized to measure room radiation levels. During 32 days, the detectors were placed in several strategically selected points inside the PET/CT center and in adjacent buildings. After the exposure period the dosimeters were collected and processed to determine the radiation level. Results In none of the points selected for measurements the values exceeded the radiation dose threshold for controlled area (5 mSv/year) or free area (0.5 mSv/year) as recommended by the Brazilian regulations. Conclusion In the present study the authors demonstrated that the whole shielding system is appropriate and, consequently, the workers are exposed to doses below the threshold established by Brazilian standards, provided the radiation protection standards are followed. PMID:25798004

Effect of ultraviolet radiation (300-400 nanometers) on polypropylene

International Nuclear Information System (INIS)

Lerman, S.

1983-01-01

Polypropylene discs and shavings were exposed to simulated ambient ultraviolet (UV) radiation (lambda 300-400 nm) for a period equivalent to at least two years of wear within the eye, assuming the eye to be exposed to ambient UV radiation for four hours per day at 1 mW/cm2. The polypropylene and the incubation media were measured by several forms of optical spectroscopy, and there was no photochemical change in either. Where polypropylene discs were exposed to a very high level of UV radiation (greater than 500 W/cm2), they became brittle and discolored within five to ten days. This level of exposure, however, was equivalent to a total of over 20 million joules/cm2, which is at least one million times levels for expected ambient UV exposure to polypropylene within the eye

[Influence of cold spot temperature on 253.7 nm resonance spectra line of electrodeless discharge lamps].

Science.gov (United States)

Dong, Jin-yang; Zhang, Gui-xin; Wang, Chang-quan

2012-01-01

As a kind of new electric light source, electrodeless discharge lamps are of long life, low mercury and non-stroboscopic light. The lighting effect of electrodeless discharge lamps depends on the radiation efficiency of 253.7 nm resonance spectra line to a large extent. The influence of cold temperature on 253.7 nm resonance spectra line has been studied experimentally by atomic emission spectral analysis. It was found that the radiation efficiency of 253.7 nm resonance spectra line is distributed in a nearly normal fashion with the variation of cold spot temperature, in other words, there is an optimum cold spot temperature for an electrodeless discharge lamp. At last, the results of experiments were analyzed through gas discharge theory, which offers guidance to the improvement of lighting effect for electrodeless discharge lamps.

Effects of UV radiation on freshwater metazooplankton

International Nuclear Information System (INIS)

Tartarotti, B.

1999-06-01

There is evidence that fluxes of solar ultraviolet-B radiation (UV-B, 290-320 nm) are increasing over wide parts of the earth's surface due to stratospheric ozone depletion. UV radiation (290-400 nm) can have damaging effects on biomolecules and cell components that are common to most living organisms. The aim of this thesis is to gain a more thorough understanding of the potential impacts of solar radiation on freshwater metazooplankton. To detect UV-vulnerability in zooplankton populations dominating the zooplankton community of two clear-water, high mountain lakes located one in the Austrian Alps and another in the Chilean Andes, the survival of two copepod species was studied. The organisms were exposed to a 10- to 100-fold increase in UV-B radiation compared to those levels found at their natural, maximum daytime distribution. Both species vertically migrate and are pigmented. UV-absorbing compounds with a maximum absorption at ∼334 nm were also detected. Cyclops abyssorum tatricus, a common cyclopoid copepod species of Alpine lakes, was highly resistant to UV-B radiation and no significant lethal effect was observed. The calanoid copepod Boeckella gracilipes, frequent in Andean lakes, had a mortality ∼5 times higher in the treatment receiving full sunlight than in the UV-B excluded treatment (3.2 %) only when exposed for 70 h. The resistance of B. gracilipes was higher than that reported in the literature for the same species suggesting the existence of intraspecific differences in UV sensitivity. Survival, fecundity and development of the zooplankton community of a clear-water, high elevation Andean lake (33 o S) were studied with mesocosms experiments after prolonged UV exposure (48 days). When exposed to full sunlight, the population of the cladoceran Chydorus sphaericus and the rotifer Lepadella ovalis were strongly inhibited by UV-B, whereas both species were resistant to UV-A radiation. Conversely, UV-B radiation had no effect on the survival of the

Does ultraviolet radiation affect the xanthophyll cycle in marine phytoplankton?

NARCIS (Netherlands)

van de Poll, W.H.; Buma, A.G.J.

2009-01-01

This Perspective summarizes the state of knowledge of the impact of ultraviolet radiation on the photoprotective xanthophyll cycle in marine phytoplankton. Excess photosynthetically active radiation (PAR; 400-700 nm) and ultraviolet radiation (UVR; 280-400 nm) affect various cellular processes and

Environments with elevated radiation levels from natural radioactive substances

International Nuclear Information System (INIS)

Sohrabi, M.

2000-01-01

Some areas in the world have elevated levels of radioactive substances in the environment forming elevated radiation areas (ERAs) where public potential annual effective doses can exceed even the dose limit of radiation workers. Such radioactive substances are either terrestrial natural radioactivity added naturally in the soil or natural and/or man-made radioactivity from human activities added into the environment. If radioactivity is added naturally, elevated natural radiation areas (ENRAs) are formed. Based on the classification criteria introduced by the author, such regions are divided into static and dynamic areas. They are also classified in accordance with their level of potential effective dose to the public. Some main ENRAs are classified. Highlights are presented of the results of activity studies carried out in selected areas. The concepts discussed can also be applied to areas formed by human activities. The author suggests some guidelines for future studies, regulatory control and decision making, bearing in mind the need for harmonization of policies for regulatory control and remedial actions at sites to protect the public from environmental chronic exposures. (author)

BEIR-III report and the health effects of low-level radiation

International Nuclear Information System (INIS)

Fabrikant, J.I.

1980-01-01

The present BEIR-III Committee has not highlighted any controversy over the health effects of low-level radiation. In its evaluation of the experimental data and epidemiological surveys, the Committee has carefully reviewed and assessed the value of all the available scientific evidence for estimating numerical risk coefficients for the health hazards to human populations exposed to low levels of ionizing radiation. Responsible public awareness of the possible health effects of ionizing radiations from medical and industrial radiation exposure, centers on three important matters of societal concern: (1) to place into perspective the extent of harm to the health of man and his descendants to be expected in the present and in the future from those societal activities involving ionizing radiation; (2) to develop quantitative indices of harm based on dose-effect relationships; such indices could then be used with prudent caution to introduce concepts of the regulation of population doses on the basis of somatic and genetic risks; and (3) to identify the magnitude and extent of radiation activities which could cause harm, to assess their relative significance, and to provide a framework for recommendations on how to reduce unnecessary radiation exposure to human populations. The main difference of the BEIR Committee Report is not so much from new data or new interpretations of existing data, but rather from a philosophical approach and appraisal of existing and future radiation protection resulting from an atmosphere of constantly changing societal conditions and public attitudes

Radiation therapy induced changes in male sex hormone levels in rectal cancer patients

International Nuclear Information System (INIS)

Dueland, Svein; Groenlie Guren, Marianne; Rune Olsen, Dag; Poulsen, Jan Peter; Magne Tveit, Kjell

2003-01-01

Background and purpose:To determine the effect of curative radiation therapy (46-50 Gy) on the sex hormone levels in male rectal cancer patients. Materials and methods:Twenty-five male rectal cancer patients (mean age 65 years), receiving pelvic radiation therapy (2 Gyx23-25 fractions in 5 weeks) were included. Serum testosterone, FSH and LH were determined before start of treatment, at the 10th and 25th fractions, and 4-6 weeks after completed radiotherapy. The testicular dose was determined by thermoluminescent dosimetry. Results:Five weeks of radiation therapy (46-50 Gy) resulted in a 100% increase in serum FSH, a 70% increase in LH, and a 25% reduction in testosterone levels. After treatment, 35% of the patients had serum testosterone levels below lower limit of reference. The mean radiation dose to the testicles was 8.4 Gy. A reduction in testosterone values was observed already after a mean dose of 3.3 Gy (10th fraction). Conclusion:Radiation therapy (46-50 Gy) for rectal cancer resulted in a significant increase in serum FSH and LH and a significant decrease in testosterone levels, indicating that sex hormone production is sensitive to radiation exposure in patients with a mean age of 65 years

Split energy level radiation detection

International Nuclear Information System (INIS)

Barnes, G.T.

1986-01-01

This patent describes an energy discriminating radiation detector comprising: (a) a first element comprising a first material of a kind which is preferentially responsive to penetrative radiation of a first energy range; (b) a second element comprising a second material different in kind from the first material and of a kind which is preferentially responsive to penetrative radiation of second energy range extending higher than the first energy range. The element is positioned to receive radiation which has penetrated through a portion of the first element; and (c) a filter of penetrative radiation interposed between the first and second elements

Alternative interpretations of statistics on health effects of low-level radiation

International Nuclear Information System (INIS)

Hamilton, L.D.

1983-01-01

Four examples of the interpretation of statistics of data on low-level radiation are reviewed: (a) genetic effects of the atomic bombs at Hiroshima and Nagasaki, (b) cancer at Rocky Flats, (c) childhood leukemia and fallout in Utah, and (d) cancer among workers at the Portsmouth Naval Shipyard. Aggregation of data, adjustment for age, and other problems related to the determination of health effects of low-level radiation are discussed. Troublesome issues related to post hoc analysis are considered

Social economical and psychological considerations in conveying potential radiation risks from high level natural background radiation to the residents of Ramsar, Iran

International Nuclear Information System (INIS)

Mortazavi, S. M. J.; Ghiassi-nejad, M.

2003-01-01

X-rays and radioactivity were discovered more than 100 years ago but the need for protection against very low doses of ionizing radiation and especially different levels of natural radiation is still among the most controversial matters in radiobiology and radiation protection. According to formal reports, some areas in Ramsar, a city in northern Iran, are the inhabited areas with the highest levels of natural radiation studied so far. A population of about 2000 is exposed to average annual radiation levels of 10.2 mGy y''-1 and the highest recorded external gamma dose rates are about 130 mGy y''-1. We have previously shown that in high background radiation areas (HBRAs), cultured human lymphocytes of the inhabitants whose cumulative radiation doses were as much as 170 times more than those of a control area when subjected to 1.5 Gy challenge dose,were significantly more radioresistant compared to the residents of the control area (Mortazavi et al. 2002a,b, Mortazavi and Karam 2002, Ghiassi-Najed et al. 2002). The people who live in these areas are usually unaware of the high levels of natural radiation in their environment. Studies performed on the residents of these areas have indicated that the effective dose of the inhabitants, in some cases, is much higher than the dose limits for occupational irradiation. Considering recent policies of ICRP regarding suggesting dose limits for exposure to natural sources of ionizing including radon, it seems that the inhabitants should become familiar with the possible risks of the exposure to high levels of ionizing radiation. They should also realize that studies performed over the past years have indicated no detrimental effect. On the other hand, according to ICRP suggestions and considering the experiences in other countries, especially evacuation of the residents of contaminated areas after Chernobyl accident, setting any radiation protection regulation for the inhabitants without considering social, economic and

Germ killing by ultraviolet radiation

International Nuclear Information System (INIS)

Wawrik, O.

1975-01-01

Short-wave UV radiation, in particular the range about 250 nm, has a high germ reducing effect. Corresponding UV burners which above all emit radiation at the line of 254 nm can therefore be used effectively in all cases where the least possible content of germs in the air is aimed at. Apart from this it is also possible to reduce by this process the germs on surfaces and liquids. Especially in the most various ranges of pharmaceutical production one is steadily striving for efficient and last not least economic procedures by which it is possible to reduce the germs present in the air of a room. Numerous scientific investigations have sufficiently proved that short-wave UV radiation is extremely well appropriate for such purposes. Absolutely germ-free air in a room can only be obtained under laboratory conditions. In practice, however, the aim is not to achieve a 100 per cent killing of the germs present in a room but to make sure that the germ rate in certain rooms is constantly reduced to the lowest possible level. If in this connection it is referred to a germ reduction of 100 or 99 per cent this is but theory. (orig.) [de

Status and initial commissioning of a high gain 800 nm SASE FEL

CERN Document Server

Tremaine, Aaron M; Murokh, A; Musumeci, P; Pellegrini, C; Rosenzweig, J; Babzien, M; Ben-Zvi, I; Johnson, E; Malone, R; Rakowsky, G; Skaritka, J; Wang, X J; Yu, L H; Van Bibber, K A; Hill, J M; Le Sage, G P; Carr, R; Cornacchia, M; Nuhn, H D; Ruland, R; Nguyen, D C

2000-01-01

We describe the status and initial commissioning of the Visible to Infrared SASE Amplifier (VISA) experiment. VISA uses a strong focusing 4 m undulator, the Brookhaven National Laboratory ATF linac with an energy of 72 MeV, and a photoinjector electron source. The VISA fundamental radiation wavelength is near 800 nm and the power expected at saturation is near 60 MW. Power, angular and spectral measurements are planned for the VISA radiation and these results will be analyzed and compared with SASE FEL theory and computer simulation. In addition, the induced electron beam micro-bunching will be measured using coherent transition radiation.

Status and initial commissioning of a high gain 800 nm SASE FEL

International Nuclear Information System (INIS)

Tremaine, A.; Frigola, P.; Murokh, A.; Musumeci, P.; Pellegrini, C.; Rosenzweig, J.; Babzien, M.; Ben-Zvi, I.; Johnson, E.; Malone, R.; Rakowsky, G.; Skaritka, J.; Wang, X.J.; Yu, L.H.; Van Bibber, K.A.; Hill, J.M.; Le Sage, G.P.; Carr, R.; Cornacchia, M.; Nuhn, H.-D.; Ruland, R.; Nguyen, D.C.

2000-01-01

We describe the status and initial commissioning of the Visible to Infrared SASE Amplifier (VISA) experiment. VISA uses a strong focusing 4 m undulator, the Brookhaven National Laboratory ATF linac with an energy of 72 MeV, and a photoinjector electron source. The VISA fundamental radiation wavelength is near 800 nm and the power expected at saturation is near 60 MW. Power, angular and spectral measurements are planned for the VISA radiation and these results will be analyzed and compared with SASE FEL theory and computer simulation. In addition, the induced electron beam micro-bunching will be measured using coherent transition radiation

Sunlight-exposed biofilm microbial communities are naturally resistant to chernobyl ionizing-radiation levels.

Directory of Open Access Journals (Sweden)

Marie Ragon

Full Text Available BACKGROUND: The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. METHODOLOGY/PRINCIPAL FINDINGS: To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta and ascomycete fungi (Ascomycota dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. CONCLUSIONS/SIGNIFICANCE: Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in

Sunlight-exposed biofilm microbial communities are naturally resistant to chernobyl ionizing-radiation levels.

Science.gov (United States)

Ragon, Marie; Restoux, Gwendal; Moreira, David; Møller, Anders Pape; López-García, Purificación

2011-01-01

The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta) and ascomycete fungi (Ascomycota) dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU) present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in terms of general diversity patterns, despite increased mutation levels at the single

Sunlight-Exposed Biofilm Microbial Communities Are Naturally Resistant to Chernobyl Ionizing-Radiation Levels

Science.gov (United States)

Ragon, Marie; Restoux, Gwendal; Moreira, David; Møller, Anders Pape; López-García, Purificación

2011-01-01

Background The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. Methodology/Principal Findings To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta) and ascomycete fungi (Ascomycota) dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU) present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. Conclusions/Significance Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in terms of general

The effect of ionizing radiation on intraocular lenses

International Nuclear Information System (INIS)

Ellerin, Bruce E.; Nisce, Lourdes Z.; Roberts, Calvin W.; Thornell, Cliff; Sabbas, Albert; Wang Huili; Li, P. Mark; Nori, Dattatreyudu

2001-01-01

Background: The native crystalline lens is the principal shield against ultraviolet radiation (UV), damage to the human retina. Every year in the United States, more than one million patients undergo removal of the natural lens in the course of cataract surgery (phakectomy), at which time an intraocular lens (IOL) is placed in the lens capsule. The IOL thenceforth serves as the principal barrier to ultraviolet radiation over the life of the implant, potentially for decades. The synthetic organic molecules of which IOLs are composed offer little UV protection unless ultraviolet-absorbing chromophores are incorporated into the lens material during manufacture. However, chromophores are alkenes potentially subject to radiolytic degradation. It is unknown whether ionizing radiation at clinical doses (e.g., to the brain or in the head-and-neck region) affects the UV-absorbing capacity of chromophore-bearing IOLs and consequently exposes the retina to potentially chronic UV damage. In addition, the polymers of which IOLs are composed are themselves subject to radiation damage, which theoretically might result in optical distortion in the visible light range. Objective: To determine whether megavoltage photon ionizing radiation alters the absorption spectra of ultraviolet-shielding polymethylmethacrylate (PMMA) and organopolysiloxane (silicone) intraocular lenses (IOLs) in the UV (280 nm ≤ λ < 400 nm), visible (400 nm ≤ λ ≤ 700 nm), and low-end near-infrared (700 nm < λ ≤ 830 nm) ranges. Design: Prospective, nonrandomized trial of dose-paired IOL cohorts. Methods: Fourteen IOLs, seven of PMMA (Chiron 6842B) and seven of silicone (IOLAB L141U), were paired and examined for absorption spectra in 1-nm intervals over the range λ = 280-830 nm on a Cary 400 deuterium and quartz halogen source-lamp UV/visible spectrophotometer before and after undergoing megavoltage ionizing irradiation to doses of 2, 5, 10, 20, 40, 60, and 100 Gray, respectively. Because of

The effect of MLS laser radiation on cell lipid membrane.

Science.gov (United States)

Pasternak, Kamila; Wróbel, Dominika; Nowacka, Olga; Pieszyński, Ireneusz; Bryszewska, Maria; Kujawa, Jolanta

2018-03-14

Authors of numerous publications have proved the therapeutic effect of laser irradiation on biological material, but the mechanisms at cellular and subcellular level are not yet well understood. The aim of this study was to assess the effect of laser radiation emitted by the MLS M1 system (Multiwave Locked System) at two wavelengths (808 nm continuous and 905 nm pulsed) on the stability and fluidity of liposomes with a lipid composition similar to that of human erythrocyte membrane or made of phosphatidylocholine. Liposomes were exposed to low-energy laser radiation at surface densities 195 mW/cm2 (frequency 1,000 Hz) and 230 mW/cm2 (frequency 2,000 Hz). Different doses of radiation energy in the range 0-15 J were applied. The surface energy density was within the range 0.46 - 4.9 J/cm 2. The fluidity and stability of liposomes subjected to such irradiation changed depending on the parameters of radiation used. Since MLS M1 laser radiation, depending on the parameters used, affects fluidity and stability of liposomes with the lipid content similar to erythrocyte membrane, it may also cause structural and functional changes in cell membranes.

Superluminescence of cadmium sulfide crystals under pulse X-ray radiation

International Nuclear Information System (INIS)

Pavlovskaya, N.G.; Tarasov, M.D.; Balakin, V.A.; Varava, V.P.; Lobov, S.I.; Surskij, O.K.; Tsukerman, V.A.

1977-01-01

Studies were made to elucidate luminescence properties of CdS crystal radiated by short pulses of braking x-ray radiation. Such a radiation causes the appearance of superluminescence. The radiation was carried out at 295 and 170 K, the radiation dose being changed from 3600 to 1600 r/pulse. At the temperature of 295 K light luminescence was registered at the wave length of 528 nm and half-width of 15 nm. While the temperature lowers, the radiation shifts to the range of shorter wave lengths, and a decrease of the spectrum half-width is observed. With the increase of radiation dose the decrease of radiation spectrum half-width is observed. Approximate calculations show that to achieve the spectrum narrowing to 1 nm at room temperature it is necessary to increase radiation dose per pulse 5-6 times

Analysis of radiation level on dinosaur fossil in Zigong

International Nuclear Information System (INIS)

Yang Changshu; Liang Shuzhi; Fan Zhengnian.

1995-01-01

Study on radiation level of dinosaur fossil and environment in conservation zone in Zigong, Sichuan has been done. The results showed that the γ radiation dose and radioactivity strength of 232 Th and 40 K in dinosaur fossil, soil and rock in the conservation zone were within the limits of radioactive background value in Zigong. Radioactivity strength of 238 U, 226 Ra in dinosaur fossil were 26.6 and 29.2 times higher than the rock of same layer respectively

Effect of aromatic compounds on radiation resistance of polymers studied by optical emission

International Nuclear Information System (INIS)

Kawanishi, Shunichi; Hagiwara, Miyuki

1987-10-01

To clarify the effects of condensed bromoacenaphthylene (con-BACN) as a newly developed flame retardant on the radiation resistance of ethylene-propylene-diene-terpolymer (EPDM), optical emission behavior of aromatic compounds, acenaphthylene and acenaphthene as model compound of con-BACN was studied. The energy absorbed in polymer matrix is transferred to the aromatic molecules very fast within 1 ns, and introduces excited states of aromatic compound. The fluorescence from naphthalene units of the additives with peak at 337 and 350 nm (named AT emission band) was observed in EPDM containing acenaphthene or acenaphthylene. When aromatic peroxide was used as a crosslinking agent, another emission band (Xn band) was observed at 400 nm. It was found that these emission bands play a role in trapping sites in which a part of radiation energy release in the form of fluorescence. The energy level of the excited state was correlated to the radiation stability measured with coloration and oxidation reaction of the polymer. Furthermore, acenaphthylene having a reactive vinyl bond forms excimer emission band Ex whose level is lower than those of AT and Xn bands, and therefore, enhances radiation stability of matrix polymer by giving effective routes for energy release. (author)

Experimental Studies of Simultaneous 351 nm and 527 nm Laser Beam Interactions in a Long Scalelength Plasma

International Nuclear Information System (INIS)

Moody, J D; Divol, L; Glenzer, S H; MacKinnon, A J; Froula, D H; Gregori, G; Kruer, W L; Suter, L J; Williams, E A; Bahr, R; Seka, W

2003-01-01

We describe experiments investigating the simultaneous backscattering from 351 nm (3w) and 527 nm (2w) interaction beams in a long scalelength laser-produced plasma for intensities (le) 1 x 10 15 W/cm 2 . Measurements show comparable scattering fractions for both color probe beams. Time resolved spectra of stimulated Raman and Brillouin scattering (SRS and SBS) indicate the effects of laser intensity and smoothing as well as plasma composition and parameters on the scattering levels

Solar Modulation of Atmospheric Cosmic Radiation:. Comparison Between In-Flight and Ground-Level Measurements

Science.gov (United States)

Iles, R. H. A.; Taylor, G. C.; Jones, J. B. L.

January 2000 saw the start of a collaborative study involving the Mullard Space Science Laboratory, Virgin Atlantic Airways, the Civil Aviation Authority and the National Physical Laboratory in a program to investigate the cosmic radiation exposure to aircrew. The study has been undertaken in view of EU Directive 96/291 (May 2000) which requires the assessment of the level of radiation exposure to aircrew. The project's aims include validation of radiation dose models and evaluation of space weather effects on atmospheric cosmic radiation levels, in particular those effects not accounted for by the models. Ground level measurements are often used as a proxy for variations in cosmic radiation dose levels at aircraft altitudes, especially during Forbush Decreases (FDs) and Solar Energetic Particle (SEP) events. Is this estimation realistic and does the ground level data accurately represent what is happening at altitude? We have investigated the effect of a FD during a flight from Hong Kong to London Heathrow on the 15th July 2000 and compared count rate and dose measurements with simultaneous variations measured at ground level. We have also compared the results with model outputs.

THE FORMATION OF IRIS DIAGNOSTICS. VII. THE FORMATION OF THE O i 135.56 NM LINE IN THE SOLAR ATMOSPHERE

Energy Technology Data Exchange (ETDEWEB)

Lin, Hsiao-Hsuan; Carlsson, Mats, E-mail: h.h.lin@astro.uio.no, E-mail: mats.carlsson@astro.uio.no [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway)

2015-11-01

The O i 135.56 nm line is covered by NASA's Interface Region Imaging Spectrograph (IRIS) small explorer mission which studies how the solar atmosphere is energized. We study here the formation and diagnostic potential of this line by means of non-local thermodynamic equilibrium modeling employing both 1D semi-empirical and 3D radiation magnetohydrodynamic models. We study the basic formation mechanisms and derive a quintessential model atom that incorporates essential atomic physics for the formation of the O i 135.56 nm line. This atomic model has 16 levels and describes recombination cascades through highly excited levels by effective recombination rates. The ionization balance O i/O ii is set by the hydrogen ionization balance through charge exchange reactions. The emission in the O i 135.56 nm line is dominated by a recombination cascade and the line is optically thin. The Doppler shift of the maximum emission correlates strongly with the vertical velocity in its line forming region, which is typically located at 1.0–1.5 Mm height. The total intensity of the line emission is correlated with the square of the electron density. Since the O i 135.56 nm line is optically thin, the width of the emission line is a very good diagnostic of non-thermal velocities. We conclude that the O i 135.56 nm line is an excellent probe of the middle chromosphere, and compliments other powerful chromospheric diagnostics of IRIS such as the Mg ii h and k lines and the C ii lines around 133.5 nm.

Occupational radiation exposure in nuclear medicine department in Kuwait

Science.gov (United States)

Alnaaimi, M.; Alkhorayef, M.; Omar, M.; Abughaith, N.; Alduaij, M.; Salahudin, T.; Alkandri, F.; Sulieman, A.; Bradley, D. A.

2017-11-01

Ionizing radiation exposure is associated with eye lens opacities and cataracts. Radiation workers with heavy workloads and poor protection measures are at risk for vision impairment or cataracts if suitable protection measures are not implemented. The aim of this study was to measure and evaluate the occupational radiation exposure in a nuclear medicine (NM) department. The annual average effective doses (Hp[10] and Hp[0.07]) were measured using calibrated thermos-luminescent dosimeters (TLDs; MCP-N [LiF:Mg,Cu,P]). Five categories of staff (hot lab staff, PET physicians, NM physicians, technologists, and nurses) were included. The average annual eye dose (Hp[3]) for NM staff, based on measurements for a typical yearly workload of >7000 patients, was 4.5 mSv. The annual whole body radiation (Hp[10]) and skin doses (Hp[0.07]) were 4.0 and 120 mSv, respectively. The measured Hp(3), Hp(10), and Hp(0.07) doses for all NM staff categories were below the dose limits described in ICRP 2014 in light of the current practice. The results provide baseline data for staff exposure in NM in Kuwait. Radiation dose optimization measures are recommended to reduce NM staff exposure to its minimal value.

Enhanced radiation tolerance of ultrafine grained Fe–Cr–Ni alloy

International Nuclear Information System (INIS)

Sun, C.; Yu, K.Y.; Lee, J.H.; Liu, Y.; Wang, H.; Shao, L.; Maloy, S.A.; Hartwig, K.T.; Zhang, X.

2012-01-01

Highlights: ► Ultrafine grained Fe-Cr-Ni alloy was processed by equal channel angular pressing technique. ► The overall Helium bubble density and dislocation loop density were reduced by grain refinement. ► The ultrafine grained microstructure alleviated radiation-induced hardening. - Abstract: The evolutions of microstructure and mechanical properties of Fe–14Cr–16Ni (wt.%) alloy subjected to Helium ion irradiations were investigated. Equal channel angular pressing (ECAP) process was used to significantly reduce the average grain size from 700 μm to 400 nm. At a peak fluence level of 5.5 displacement per atom (dpa), helium bubbles, 0.5–2 nm in diameter, were observed in both coarse-grained (CG) and ultrafine grained (UFG) alloy. The density of He bubbles, dislocation loops, as well as radiation hardening were reduced in the UFG Fe–Cr–Ni alloy comparing to those in its CG counterpart. The results imply that radiation tolerance in bulk metals can be effectively enhanced by refinement of microstructures.

What happens at very low levels of radiation exposure ? Are the low dose exposures beneficial ?

International Nuclear Information System (INIS)

Deniz, Dalji

2006-01-01

Full text: Radiation is naturally present in our environment and has been since the birth of this planet. The human population is constantly exposed to low levels of natural background radiation, primarily from environmental sources, and to higher levels from occupational sources, medical therapy, and other human-mediated events. Radiation is one of the best-investigated hazardous agents. The biological effects of ionizing radiation for radiation protection consideration are grouped into two categories: The deterministic and the stochastic ones. Deterministic radiation effects can be clinically diagnosed in the exposed individual and occur when above a certain t hreshold a n appropriately high dose is absorbed in the tissues and organs to cause the death of a large number of cells and consequently to impair tissue or organ functions early after exposure. A clinically observable biological effect (Acute Radiation Sendromes, ARS) occurs days to months after an acute radiation dose. Stochastic radiation effects are the chronic effects of radiation result from relatively low exposure levels delivered over long periods of time. These are sort of effects that might result from occupational exposure, or to the background exposure levels. Such late effects might be the development of malignant (cancerous) disease and of the hereditary consequences. These effects may be observed many years after the radiation exposure. There is a latent period between the initial radiation exposure and the development of the biological effect. For this reason, a stochastic effect is called a Linear or Zero-Threshold (LNT) Dose-Response Effect. There is a stochastic correlation between the number of cases of cancers or genetic defects developed inside a population and the dose received by the population at relatively large levels of radiation. These changes in gene activation seem to be able to modify the response of cells to subsequent radiation exposure, termed the a daptive response

Influence of ionizing radiation on gastrointestinal peptide levels

Energy Technology Data Exchange (ETDEWEB)

Wysocki, J.; Esposito, V.; Linard, C. [CEA Fontenay-aux-Roses, 92 (France). Inst. de Protection et de Surete Nucleaire

1997-03-01

Exposure of the gut to ionising radiation may induce gastrointestinal damage and dysfunction. Early effects such as nausea, vomiting and diarrhea, anorexia may be observed within the first 24 h after irradiation. Such symptoms are seen even with doses as low as 1 Gy. later effects and the onset of the gastrointestinal syndrome are seen at higher doses (10 Gy) and include gastric emptying inhibition, intestinal hemorrhages, disturbances in water and electrolytes balance and septicemia. The severity of which depends on the nature, dose and dose rate received. The mechanism underlying these changes was unclear; it has long been known that exposure to ionising radiation affects intestinal morphology usually because of inhibition of mitotic activity at the level of the crypt enterocyst. The various physiological functions of the gastrointestinal tract are controlled by a wide variety of agents as neurotransmitters, neuropeptides. Radiation induces alterations in hormonal release and response. The present study carried out in the rat focuses on Gastrin Releasing Peptide (GRP), a gastrointestinal neuropeptide present in the central nervous system and in the gut endocrine cells were released into blood. The GRP controls food intake, pancreatic enzyme secretions, gastric emptying, intestinal motility and cellular proliferation. The aim was to investigate the effects of gamma and neutron/gamma on plasma and gastrointestinal tissue levels of GRP

The role of coccoliths in protecting Emiliania huxleyi against stressful light and UV radiation

Science.gov (United States)

Xu, Juntian; Bach, Lennart T.; Schulz, Kai G.; Zhao, Wenyan; Gao, Kunshan; Riebesell, Ulf

2016-08-01

Coccolithophores are a group of phytoplankton species which cover themselves with small scales (coccoliths) made of calcium carbonate (CaCO3). The reason why coccolithophores form these calcite platelets has been a matter of debate for decades but has remained elusive so far. One hypothesis is that they play a role in light or UV protection, especially in surface dwelling species like Emiliania huxleyi, which can tolerate exceptionally high levels of solar radiation. In this study, we tested this hypothesis by culturing a calcified and a naked strain under different light conditions with and without UV radiation. The coccoliths of E. huxleyi reduced the transmission of visible radiation (400-700 nm) by 7.5 %, that of UV-A (315-400 nm) by 14.1 % and that of UV-B (280-315 nm) by 18.4 %. Growth rates of the calcified strain (PML B92/11) were about 2 times higher than those of the naked strain (CCMP 2090) under indoor constant light levels in the absence of UV radiation. When exposed to outdoor conditions (fluctuating sunlight with UV radiation), growth rates of calcified cells were almost 3.5 times higher compared to naked cells. Furthermore, the relative electron transport rate was 114 % higher and non-photochemical quenching (NPQ) was 281 % higher in the calcified compared to the naked strain, implying higher energy transfer associated with higher NPQ in the presence of calcification. When exposed to natural solar radiation including UV radiation, the maximal quantum yield of photosystem II was only slightly reduced in the calcified strain but strongly reduced in the naked strain. Our results reveal an important role of coccoliths in mitigating light and UV stress in E. huxleyi.

Role of DNA damage in ultraviolet (313 nm) inactivation of yeasts Saccharomyces cerevisial

International Nuclear Information System (INIS)

Pospelov, M.E.; Ivanova, Eh.V.; Frajkin, G.Ya.

1984-01-01

Relative contribution of photoinhibition of cell respiration and DNA damage to lethal effect, caused by ultraviolet (UV) radiation of 313 m in certain yeast strains Saccharomyces cerevisiae, has been studied. It is shown that cell inactivation is mainly conditioned by DNA photodamage. When studying photoreactivation it has been established, that dimers of pyrimidine bases are the main lethal photoproducts, formed in DNA Under the effect of UV-radiation of 313 nm

Vessel used in radiation counting to determine radioactivity levels

International Nuclear Information System (INIS)

Charlton, J.C.; Glover, J.S.; Shephard, B.P.

1977-01-01

This invention concerns the vessels used in radiation counting to determine radioactivity levels. These vessels prove to be particularly useful in analyses of the kind where a radioactive element or compound is separated into two phases and the radioactivity of one phase is determined. Such a vessel used in the counting of radiation includes an organic plastic substance tube appreciably cylindrical in shape whose upper end is open whilst the lower end is closed and integral with it, and an anti-radiation shield in metal or in metal reinforced plastic located at the lower end of the tube and extending along the wall of the tube up to a given height. The vessel contains a reaction area of 1 to 10 ml for holding fluid reagents [fr

Benefits from the BESSY FEL Higher Harmonic Radiation

CERN Document Server

Goldammer, K

2005-01-01

In the FEL process, bunching and coherent radiation is produced at the fundamental frequency as well as its higher harmonics. BESSY proposes a linac-based cascaded High-Gain Harmonic-Generation (HGHG) free electron laser (FEL) multi-user facility. The BESSY soft X-ray FEL will be seeded by three lasers spanning the spectral range of 230nm to 460nm. Two to four HGHG stages downconvert the seed wavelength to the desired radiation range of 1.24nm to 51nm using higher harmonic bunching. As a surplus, higher harmonic radiation is intrinsically produced in each FEL stage. Radiation on a higher harmonic of the FEL frequency is of high interest because it yields the possibility to reduce the number of FEL stages. This paper details extensive studies of the higher harmonic content of the BESSY FEL radiation. Important aspects of FEL interaction on higher harmonics as resulting from theory and from numerical simulations are discussed. For the case of the BESSY FEL, methods for improving the harmonic content are present...

Radiation levels at CERN's injectors and their impact on electronic equipment

CERN Document Server

AUTHOR|(SzGeCERN)649218; Brugger, Markus

2013-01-01

Electronic devices operating in hostile radiation environments, such as those found close to high-energy particle accelerators, can suffer from different types of radiation induced failures. At CERN, the mixed particle and energy radiation fields present at the Large Hadron Collider (LHC) and its injector chain can give rise to both stochastic and cumulative effects causing radiation induced failures of exposed electronics and materials, thus directly impacting components and system lifetimes, as well as maintenance requirements. With its original focus on the LHC, the Radiation to Electronics (R2E) project has been successfully implementing mitigation actions in order to avoid accelerator downtime due to radiation induced failures on active electronics. In a next step, the emphasis is put on CERN's injector chain, collecting the respective available information about radiation levels, the definition of additional monitoring requirements and a critical analysis of present and future equipment installations. T...

Biological effects and medical applications of infrared radiation.

Science.gov (United States)

Tsai, Shang-Ru; Hamblin, Michael R

2017-05-01

Infrared (IR) radiation is electromagnetic radiation with wavelengths between 760nm and 100,000nm. Low-level light therapy (LLLT) or photobiomodulation (PBM) therapy generally employs light at red and near-infrared wavelengths (600-100nm) to modulate biological activity. Many factors, conditions, and parameters influence the therapeutic effects of IR, including fluence, irradiance, treatment timing and repetition, pulsing, and wavelength. Increasing evidence suggests that IR can carry out photostimulation and photobiomodulation effects particularly benefiting neural stimulation, wound healing, and cancer treatment. Nerve cells respond particularly well to IR, which has been proposed for a range of neurostimulation and neuromodulation applications, and recent progress in neural stimulation and regeneration are discussed in this review. The applications of IR therapy have moved on rapidly in recent years. For example, IR therapy has been developed that does not actually require an external power source, such as IR-emitting materials, and garments that can be powered by body heat alone. Another area of interest is the possible involvement of solar IR radiation in photoaging or photorejuvenation as opposites sides of the coin, and whether sunscreens should protect against solar IR? A better understanding of new developments and biological implications of IR could help us to improve therapeutic effectiveness or develop new methods of PBM using IR wavelengths. Copyright © 2016. Published by Elsevier B.V.

Lead extraction by selective operation of a nanosecond-pulsed 355nm laser

Science.gov (United States)

Herzog, Amir; Bogdan, Stefan; Glikson, Michael; Ishaaya, Amiel A.; Love, Charles

2016-03-01

Lead extraction (LE) is necessary for patients who are suffering from a related infection, or in opening venous occlusions that prevent the insertion of additional lead. In severe cases of fibrous encapsulation of the lead within a vein, laser-based cardiac LE has become one of the foremost methods of removal. In cases where the laser radiation (typically at 308 nm wavelength) interacts with the vein wall rather than with the fibrotic lesion, severe injury and subsequent bleeding may occur. Selective tissue ablation was previously demonstrated by a laser operating in the UV regime; however, it requires the use of sensitizers (e.g.: tetracycline). In this study, we present a preliminary examination of efficacy and safety aspects in the use of a nanosecond-pulsed solid-state laser radiation, at 355 nm wavelength, guided in a catheter consisting of optical fibers, in LE. Specifically, we demonstrate a correlation between the tissue elasticity and the catheter advancement rate, in ex-vivo experiments. Our results indicate a selectivity property for specific parameters of the laser radiation and catheter design. The selectivity is attributed to differences in the mechanical properties of the fibrotic tissue and a normal vein wall, leading to a different photomechanical response of the tissue's extracellular matrix. Furthermore, we performed successful in-vivo animal trials, providing a basic proof of concept for using the suggested scheme in LE. Selective operation using a 355 nm laser may reduce the risk of blood vessel perforation as well as the incidence of major adverse events.

Phase-shifted Bragg grating inscription in PMMA microstructured POF using 248 nm UV radiation

OpenAIRE

Pereira, L.; Pospori, A.; Antunes, Paulo; Domingues, Maria Fatima; Marques, S.; Bang, Ole; Webb, David J.; Marques, Carlos A.F.

2017-01-01

In this work we experimentally validate and characterize the first phase-shifted polymer optical fiber Bragg gratings (PS-POFBGs) produced using a single pulse from a 248 nm krypton fluoride laser. A single-mode poly (methyl methacrylate) optical fiber with a core doped with benzyl dimethyl ketal for photosensitivity improvement was used. A uniform phase mask customized for 850 nm grating inscription was used to inscribe these Bragg structures. The phase shift defect was created directly duri...

Environmental policy. Ambient radioactivity levels and radiation doses in 1998

International Nuclear Information System (INIS)

1999-11-01

The report contains information on the natural (background) radiation exposure (chapter II), the natural radiation exposure as influenced by anthropogenic effects (chapter III), the anthropogenic radiation exposure (chapter IV), and the radiation doses to the environment and the population emanating from the Chernobyl fallout (chapter V). The natural radiation exposure is specified referring to the contributions from cosmic and terrestrial background radiation and intake of natural radioactive substances. Changes of the natural environment resulting from anthropogenic effects (technology applications) inducing an increase in concentration of natural radioactive substances accordingly increase the anthropogenic radiation exposure. Indoor air radon concentration in buildings for instance is one typical example of anthropogenic increase of concentration of natural radioactivity, primarily caused by the mining industry or by various materials processing activities, which may cause an increase in the average radiation dose to the population. Measurements so far show that indoor air concentration of radon exceeds a level of 200 Bq/m 3 in less than 2% of the residential buildings; the EUropean Commission therefore recommends to use this concentration value as a maximum value for new residential buildings. Higher concentrations are primarily measured in areas with relevant geological conditions and abundance of radon, or eg. in mining areas. (orig./CB) [de

Pixel front-end development in 65 nm CMOS technology

International Nuclear Information System (INIS)

Havránek, M; Hemperek, T; Kishishita, T; Krüger, H; Wermes, N

2014-01-01

Luminosity upgrade of the LHC (HL-LHC) imposes severe constraints on the detector tracking systems in terms of radiation hardness and capability to cope with higher hit rates. One possible way of keeping track with increasing luminosity is the usage of more advanced technologies. Ultra deep sub-micron CMOS technologies allow a design of complex and high speed electronics with high integration density. In addition, these technologies are inherently radiation hard. We present a prototype of analog pixel front-end integrated circuit designed in 65 nm CMOS technology with applications oriented towards the ATLAS Pixel Detector upgrade. The aspects of ultra deep sub-micron design and performance of the analog pixel front-end circuits will be discussed

Low-level radiation: a review of current estimates of hazards to human populations

International Nuclear Information System (INIS)

Myers, D.K.

1977-12-01

Mankind has always lived with low levels of ionizing radiation from natural sources. This ionizing radiation may induce cancers in irradiated persons and genetic defects in the descendents of irradiated persons. The internationally accepted estimates of risks suggest that the numbers of cancers and genetic defects induced in the general population by natural background radiation are not more than about 1% of the numbers of cancers and genetic defects normally present in the general population. The added risks to the general public due to any prospective nuclear power program are minute compared to those from background radiation. At the maximum permissible levels of radiation exposures for occupational workers, the predicted number of fatal cancers induced would lead to a reduction in average life-span from 73.0 years to about 72.7 years. Since occupational exposures are usually much less than maximum permissible levels, the risks are correspondingly reduced. These occupational risks are comparable to those in most other industries and occupations. Some areas of uncertainty in the accepted risk estimates are discussed in detail in this review. (author)

Radiation exposure in the young level 1 trauma patient: a retrospective review.

Science.gov (United States)

Gottschalk, Michael B; Bellaire, Laura L; Moore, Thomas

2015-01-01

Computed tomography (CT) has become an increasingly popular and powerful tool for clinicians managing trauma patients with life-threatening injuries, but the ramifications of increasing radiation burden on individual patients are not insignificant. This study examines a continuous series of 337 patients less than 40 years old admitted to a level 1 trauma center during a 4-month period. Primary outcome measures included number of scans; effective dose of radiation from radiographs and CT scans, respectively; and total effective dose from both sources over patients' hospital stays. Several variables, including hospital length of stay, initial Glasgow Coma Scale score, and Injury Severity Score, correlated with greater radiation exposure. Blunt trauma victims were more prone to higher doses than those with penetrating or combined penetrating and blunt trauma. Location and mechanism of injury were also found to correlate with radiation exposure. Trauma patients as a group are exposed to high levels of radiation from X-rays and CT scans, and CT scans contribute a very high proportion (91.3% ± 11.7%) of that radiation. Certain subgroups of patients are at a particularly high risk of exposure, and greater attention to cumulative radiation dose should be paid to patients with the above mentioned risk factors.

Generation of polypeptide-templated gold nanoparticles using ionizing radiation.

Science.gov (United States)

Walker, Candace Rae; Pushpavanam, Karthik; Nair, Divya Geetha; Potta, Thrimoorthy; Sutiyoso, Caesario; Kodibagkar, Vikram D; Sapareto, Stephen; Chang, John; Rege, Kaushal

2013-08-13

Ionizing radiation, including γ rays and X-rays, are high-energy electromagnetic radiation with diverse applications in nuclear energy, astrophysics, and medicine. In this work, we describe the use of ionizing radiation and cysteine-containing elastin-like polypeptides (C(n)ELPs, where n = 2 or 12 cysteines in the polypeptide sequence) for the generation of gold nanoparticles. In the presence of C(n)ELPs, ionizing radiation doses higher than 175 Gy resulted in the formation of maroon-colored gold nanoparticle dispersions, with maximal absorbance at 520 nm, from colorless metal salts. Visible color changes were not observed in any of the control systems, indicating that ionizing radiation, gold salt solution, and C(n)ELPs were all required for nanoparticle formation. The hydrodynamic diameters of nanoparticles, determined using dynamic light scattering, were in the range of 80-150 nm, while TEM imaging indicated the formation of gold cores 10-20 nm in diameter. Interestingly, C2ELPs formed 1-2 nm diameter gold nanoparticles in the absence of radiation. Our results describe a facile method of nanoparticle formation in which nanoparticle size can be tailored based on radiation dose and C(n)ELP type. Further improvements in these polypeptide-based systems can lead to colorimetric detection of ionizing radiation in a variety of applications.

Assessing risks from occupational exposure to low-level radiation

International Nuclear Information System (INIS)

Gilbert, E.S.

1989-06-01

Currently, several epidemiological studies of workers who have been exposed occupationally to radiation are being conducted. These include workers in the United States, Great Britain, and Canada, involved in the production of both defense materials and nuclear power. A major reason for conducting these studies is to evaluate possible adverse health effects that may have resulted because of the radiation exposure received. The general subject of health effects resulting from low levels of radiation, including these worker studies, has attracted the attention of various news media, and has been the subject of considerable controversy. These studies provide a good illustration of certain other aspects of the statistician's role; namely, communication and adequate subject matter knowledge. A competent technical job is not sufficient if these other aspects are not fulfilled

Photosynthetic Performance of the Red Alga Pyropia haitanensis During Emersion, With Special Reference to Effects of Solar UV Radiation, Dehydration and Elevated CO2 Concentration.

Science.gov (United States)

Xu, Juntian; Gao, Kunshan

2015-11-01

Macroalgae distributed in intertidal zones experience a series of environmental changes, such as periodical desiccation associated with tidal cycles, increasing CO2 concentration and solar UVB (280-315 nm) irradiance in the context of climate change. We investigated how the economic red macroalga, Pyropia haitanensis, perform its photosynthesis under elevated atmospheric CO2 concentration and in the presence of solar UV radiation (280-400 nm) during emersion. Our results showed that the elevated CO2 (800 ppmv) significantly increased the photosynthetic carbon fixation rate of P. haitanensis by about 100% when the alga was dehydrated. Solar UV radiation had insignificant effects on the net photosynthesis without desiccation stress and under low levels of sunlight, but significantly inhibited it with increased levels of desiccation and sunlight intensity, to the highest extent at the highest levels of water loss and solar radiation. Presence of UV radiation and the elevated CO2 acted synergistically to cause higher inhibition of the photosynthetic carbon fixation, which exacerbated at higher levels of desiccation and sunlight. While P. haitanensis can benefit from increasing atmospheric CO2 concentration during emersion under low and moderate levels of solar radiation, combined effects of elevated CO2 and UV radiation acted synergistically to reduce its photosynthesis under high solar radiation levels during noon periods. © 2015 The American Society of Photobiology.

Validity of the linear no-threshold (LNT) hypothesis in setting radiation protection regulations for the inhabitants in high level natural radiation areas of Ramsar, Iran

International Nuclear Information System (INIS)

Mortazavi, S.M.J.; Atefi, M.; Razi, Z.; Mortazavi Gh

2010-01-01

Some areas in Ramsar, a city in northern Iran, have long been known as inhabited areas with the highest levels of natural radiation. Despite the fact that the health effects of high doses of ionizing radiation are well documented, biological effects of above the background levels of natural radiation are still controversial and the validity of the LNT hypothesis in this area, has been criticized by many investigators around the world. The study of the health effects of high levels of natural radiation in areas such as Ramsar, help scientists to investigate the biological effects without the need for extrapolating the observations either from high doses of radiation to low dose region or from laboratory animals to humans. Considering the importance of these studies, National Radiation Protection Department (NRPD) of the Iranian Nuclear Regulatory Authority has started an integrative research project on the health effects of long-term exposure to high levels of natural radiation. This paper reviews findings of the studies conducted on the plants and humans living or laboratory animals kept in high level natural radiation areas of Ramsar. In human studies, different end points such as DNA damage, chromosome aberrations, blood cells and immunological alterations are discussed. This review comes to the conclusion that no reproducible detrimental health effect has been reported so far. In this paper the validity of LNT hypothesis in the assessment of the health effects of high levels of natural radiation is discussed. (author)

Laser Application in Dentistry: Irradiation Effects of Nd:YAG 1064 nm and Diode 810 nm and 980 nm in Infected Root Canals—A Literature Overview

Science.gov (United States)

Kuypers, Thorsten; Gutknecht, Norbert

2016-01-01

Objective. In endodontics, Nd:YAG laser (1064 nm) and diode laser (810 nm and 980 nm) devices are used to remove bacteria in infected teeth. A literature review was elaborated to compare and evaluate the advantages and disadvantages of using these lasers. Methods. Using combined search terms, eligible articles were retrieved from PubMed and printed journals. The initial search yielded 40 titles and 27 articles were assigned to full-text analysis. The studies were classified based upon laser source, laser energy level, duration/similarity of application, and initial and final bacterial count at a minimum of 20 prepared root canals. Part of the analysis was only reduced microorganisms and mechanically treated root canals upon preparation size of ISO 30. All studies were compared to evaluate the most favorable laser device for best results in endodontic therapy. Results. A total of 22 eligible studies were found regarding Nd:YAG laser 1064 nm. Four studies fulfilled all demanded criteria. Seven studies referring to the diode laser 980 nm were examined, although only one fulfilled all criteria. Eleven studies were found regarding the diode laser 810 nm, although only one study fulfilled all necessary criteria. Conclusions. Laser therapy is effective in endodontics, although a comparison of efficiency between the laser devices is not possible at present due to different study designs, materials, and equipment. PMID:27462611

Laser Application in Dentistry: Irradiation Effects of Nd:YAG 1064 nm and Diode 810 nm and 980 nm in Infected Root Canals-A Literature Overview.

Science.gov (United States)

Saydjari, Yves; Kuypers, Thorsten; Gutknecht, Norbert

2016-01-01

Objective. In endodontics, Nd:YAG laser (1064 nm) and diode laser (810 nm and 980 nm) devices are used to remove bacteria in infected teeth. A literature review was elaborated to compare and evaluate the advantages and disadvantages of using these lasers. Methods. Using combined search terms, eligible articles were retrieved from PubMed and printed journals. The initial search yielded 40 titles and 27 articles were assigned to full-text analysis. The studies were classified based upon laser source, laser energy level, duration/similarity of application, and initial and final bacterial count at a minimum of 20 prepared root canals. Part of the analysis was only reduced microorganisms and mechanically treated root canals upon preparation size of ISO 30. All studies were compared to evaluate the most favorable laser device for best results in endodontic therapy. Results. A total of 22 eligible studies were found regarding Nd:YAG laser 1064 nm. Four studies fulfilled all demanded criteria. Seven studies referring to the diode laser 980 nm were examined, although only one fulfilled all criteria. Eleven studies were found regarding the diode laser 810 nm, although only one study fulfilled all necessary criteria. Conclusions. Laser therapy is effective in endodontics, although a comparison of efficiency between the laser devices is not possible at present due to different study designs, materials, and equipment.

Soft errors in 10-nm-scale magnetic tunnel junctions exposed to high-energy heavy-ion radiation

Science.gov (United States)

Kobayashi, Daisuke; Hirose, Kazuyuki; Makino, Takahiro; Onoda, Shinobu; Ohshima, Takeshi; Ikeda, Shoji; Sato, Hideo; Inocencio Enobio, Eli Christopher; Endoh, Tetsuo; Ohno, Hideo

2017-08-01

The influences of various types of high-energy heavy-ion radiation on 10-nm-scale CoFeB-MgO magnetic tunnel junctions with a perpendicular easy axis have been investigated. In addition to possible latent damage, which has already been pointed out in previous studies, high-energy heavy-ion bombardments demonstrated that the magnetic tunnel junctions may exhibit clear flips between their high- and low-resistance states designed for a digital bit 1 or 0. It was also demonstrated that flipped magnetic tunnel junctions still may provide proper memory functions such as read, write, and hold capabilities. These two findings proved that high-energy heavy ions can produce recoverable bit flips in magnetic tunnel junctions, i.e., soft errors. Data analyses suggested that the resistance flips stem from magnetization reversals of the ferromagnetic layers and that each of them is caused by a single strike of heavy ions. It was concurrently found that an ion strike does not always result in a flip, suggesting a stochastic process behind the flip. Experimental data also showed that the flip phenomenon is dependent on the device and heavy-ion characteristics. Among them, the diameter of the device and the linear energy transfer of the heavy ions were revealed as the key parameters. From their dependences, the physical mechanism behind the flip was discussed. It is likely that a 10-nm-scale ferromagnetic disk loses its magnetization due to a local temperature increase induced by a single strike of heavy ions; this demagnetization is followed by a cooling period associated with a possible stochastic recovery process. On the basis of this hypothesis, a simple analytical model was developed, and it was found that the model accounts for the results reasonably well. This model also predicted that magnetic tunnel junctions provide sufficiently high soft-error reliability for use in space, highlighting their advantage over their counterpart conventional semiconductor memories.

Solar Electromagnetic Radiation Study for Solar Cycle 22: Solar Ultraviolet Irradiance, 120 to 300 NM: Report of Working Groups 2 and 3 of SOLERS 22

Science.gov (United States)

Rottman, G. J.; Cebula, R. P.; Gillotay, D.; Simon, P. A.

1996-01-01

This report summarizes the activities of Working Group 2 and Working Group 3 of the SOLax Electromagnetic Radiation Study for Solar Cycle 22 (SOLERS22) Program. The international (SOLERS22) is Project 1.2 of the Solar-Terrestrial Energy Program (STEP) sponsored by SCOSTEP, a committee of the International Council of Scientific Unions). SOLERS22 is comprised of five Working Groups, each concentrating on a specific wave-length range: WG-1 - visible and infrared, WG-2 - mid-ultraviolet (200 < A < 300 nm), WG-3 - Far-ultraviolet (lambda greater than 100 and lambda less than 200 nanometers), WG-4 - extreme-ultraviolet (lambda greater than 10 and lambda less than 100 nm), and WG-5 - X-ray (lambda greater than 1 and lambda less than 10 nano meters). The overarching goals of SOLERS22 are to: 1) establish daily solar irradiance values in the specified wavelength ranges, 2) consider the evolving solar structures as the cause of temporal variations, and 3) understand the underlying physical processes driving these changes.

Does a leaf absorb radiation in the near infrared (780-900 nm) region? A new approach to quantifying optical reflection, absorption and transmission of leaves.

Science.gov (United States)

Merzlyak, Mark N; Chivkunova, Olga B; Melø, T B; Naqvi, K Razi

2002-01-01

The following question is addressed here: do healthy leaves absorb, as the spectra published over the last 50 years indicate, some 5-20% of incident radiation in the 780-900 nm region? The answer is found to be negative, and previous findings result from incomplete collection of the transmitted light by the detection system (even when the leaf is placed next to, but outside, the entrance port of an integrating sphere). A simple remedy for this inherent flaw in the experimental arrangement is applied successfully to leaves (of 10 unrelated species) differing in thickness, age and pigment content. The study has shown that, from an optical standpoint, a leaf tissue is a highly scattering material, and the infinite reflectance of a leaf is exceedingly sensitive to trace amounts of absorbing components. It is shown that water contributes, in a thick leaf (Kalanchoe blossfeldiana), an easily detectable signal even in the 780-900 nm region. The practical benefits resulting from improved measurements of leaf spectra are pointed out.

Beam-foil level lifetimes in krypton III

International Nuclear Information System (INIS)

Coetzer, F.J.; Kotze, P.B.; Westhuizen, P. van der

1982-01-01

The radiative lifetimes of levels in doubly-ionized Krypton have been measured after foil excitation of a beam of Krypton particles in the wavelength range 120-500 nm. The results are compared with the experimental values obtained by Fink et al., as well as theoretical values resulting from Coulomb (C.A.) and single configuration Hartree-Fock (H.F.) calculations. (orig.)

Are we at risk from level radiation - DNA repair capacity studies

International Nuclear Information System (INIS)

Riklis, E.; Kol, R.; Heimer, Y.M.

1979-01-01

A new biochemical method, based on determination of DNA repair capability, which will enable predetermination of radiation sensitivity and further - an indication of inherent sensitivity which may be expressed only in the future when a cell will be faced with a situation in which its repair capacity will have to function to its full capability was developed. Cells are treated with trioxalen (trimethylpsoralen, TMP) and near ultraviolet light (NUV), bringing about an almost complete cessation of semiconservative DNA synthesis, 99.5 to 99.8 % inhibition. This method enabled the accurate measurement of incorporation of labelled thymidine into DNA following assaults by radiation or chemicals, indicating that repair synthesis is occurring. The method has been found suitable for the following cells: human fibroblasts, human breast cancer cells, chinese hamster V-79 cells, human lymphocytes. Since the method is applicable also for lymphocytes, it will enable carrying out a world-wide interlaboratory comparative study in which the range of 'repair capacity' of 'normal healthy' humans will be established. Individuals showing no repair capacity will not be permitted to be exposed to any level of radiation above natural background. These are the persons 'at risk' from radiation, while the general public, showing normal repair capacity may be considered safe from the effects of low-level radiations. (B.G.)

Background radiation levels and medical exposure levels in Australia

International Nuclear Information System (INIS)

Webb, D.V.; Solomon, S.B.; Thomson, J.E.M.

1999-01-01

The average effective background dose received by the Australian population has been reassessed to be ∼1.5 millisievert (mSv) per year. Over half of this exposure arises from exposure from terrestrial radiation and cosmic rays, the remainder from radionuclides within the body and from inhalation of radon progeny. This background is to be compared with medical radiation, primarily diagnostic, which could add half as much again to the population exposure. This paper reviews research programmes carried out by the Australian Radiation Laboratory to study radiation exposure from natural background and from medical use. While the latter exposure is accepted to have a social benefit, there is a need to ensure that doses are no more than necessary to provide effective diagnosis and optimal treatment. Copyright (1999) Australasian Radiation Protection Society Inc

Electromagnetic Radiation Disturbed the Photosynthesis of Microcystis aeruginosa at the Proteomics Level.

Science.gov (United States)

Tang, Chao; Yang, Chuanjun; Yu, Hui; Tian, Shen; Huang, Xiaomei; Wang, Weiyi; Cai, Peng

2018-01-11

Photosynthesis of Microcystis aeruginosa under Electromagnetic Radiation (1.8 GHz, 40 V/m) was studied by using the proteomics. A total of 30 differentially expressed proteins, including 15 up-regulated and 15 down-regulated proteins, were obtained in this study. The differentially expressed proteins were significantly enriched in the photosynthesis pathway, in which the protein expression levels of photosystems II cytochrome b559 α subunit, cytochrome C550, PsbY, and F-type ATP synthase (a, b) decreased. Our results indicated that electromagnetic radiation altered the photosynthesis-related protein expression levels, and aimed at the function of photosynthetic pigments, photosystems II potential activity, photosynthetic electron transport process, and photosynthetic phosphorylation process of M. aeruginosa. Based on the above evidence, that photoreaction system may be deduced as a target of electromagnetic radiation on the photosynthesis in cyanobacteria; the photoreaction system of cyanobacteria is a hypothetical "shared target effector" that responds to light and electromagnetic radiation; moreover, electromagnetic radiation does not act on the functional proteins themselves but their expression processes.

Radiation effects on radiation-hardened KU and KS-4V optical fibres

International Nuclear Information System (INIS)

Ivanov, A.A.; Tugarinov, S.N.; Kaschuck, Y.A.; Krasilnikov, A.V.; Bender, S.E.

1999-01-01

The aim of this work was to test the un-pretreated and the hardened (H 2 -loaded and pre-irradiated) KS-4V and KU optical fibres in reactor environment by in-situ measurements of both the radiation-induced loss and the luminescence in the visible spectral region. Both the radio-luminescent and the transmission spectra were in-situ detected during irradiation by charge-coupled-device (CCD) linear detector in the visible spectral region of 400 to 700 nm. The radiation induced loss spectra at the fast neutron fluence of 2*10 6 n/cm 2 shows the hardened, H 2 -loading and pre-irradiating effects in the both KU and KS-4V fibres. KU un-pretreated fibre shows a big radiation absorption band of non-bridging oxygen centered at the wavelength of 630 nm. It appears that the KS-4V hardened fibre has a specific point in the loss spectrum in the vicinity of 460 nm. Other measurements were performed, particularly after reactor shutdown and at 3 different neutron fluences with constant neutron flux after restarting

Effects of combined radiofrequency radiation exposure on levels of reactive oxygen species in neuronal cells

International Nuclear Information System (INIS)

Kang, Kyoung Ah; Lee, Hyung Chul; Lee, Je-Jung

2014-01-01

The objective of this study was to investigate the effects of the combined RF radiation (837 MHz CDMA plus 1950 MHz WCDMA) signal on levels of intracellular reactive oxygen species (ROS) in neuronal cells. Exposure of the combined RF signal was conducted at specific absorption rate values of 2 W/kg of CDMA plus 2 W/kg of WCDMA for 2 h. Co-exposure to combined RF radiation with either H 2 O 2 or menadione was also performed. The experimental exposure groups were incubator control, sham-exposed, combined RF radiation-exposed with or without either H 2 O 2 or menadione groups. The intracellular ROS level was measured by flow cytometry using the fluorescent probe dichlorofluorescein diacetate. Intracellular ROS levels were not consistently affected by combined RF radiation exposure alone in a time-dependent manner in U87, PC12 or SH-SY5Y cells. In neuronal cells exposed to combined RF radiation with either H 2 O 2 or menadione, intracellular ROS levels showed no statically significant alteration compared with exposure to menadione or H 2 O 2 alone. These findings indicate that neither combined RF radiation alone nor combined RF radiation with menadione or H 2 O 2 influences the intracellular ROS level in neuronal cells such as U87, PC12 or SH-SY5Y. (author)

Level of knowledge among the population of radiation safety basic issues

Directory of Open Access Journals (Sweden)

S. A. Zelencova

2015-01-01

Full Text Available The goal of research was to determine the level of knowledge among the population on issues like sources of ionising radiation, methods of ionising radiation measurement, measures of self-protection in case of threating or actual radioactive pollution in the district, and to study self-estimation by the population of their knowledge of radiation safety issues. Research was carried out using the method of questioning of population groups in three regions close to the places of previous peaceful nuclear explosions (Arkhangelsk, Murmansk and Tyumen regions, and in five Far East regions of the Russian Federation (Kamchatka, Khabarovsk, Primorsky, Magadan and South-Sakhalin regions after radiation accident in Japan at "Fukushima-1" NPP. This research included processing of 243 questionnaires from the regions close to places of previous peaceful nuclear explosions and 216 questionnaires from the Far East regions.The analysis of obtained questioning results enabled to make the following conclusions: the level of knowledge among the population about the basic concepts of radiation safety appeared to be generally low among respondents of all eight territories. Considerable number of respondents in seven groups correctly mentioned the x-ray device as a source of ionising radiation (from 71 to 88 % of answers. In Murmansk region – only 52 % of the answers. Respondents of the same seven groups often correctly answered the question on how to detect ionising radiation (only with devices – from 68 to 98 % in different groups. The smallest number of correct answers to this question (42 % is also noted among respondents from the Murmansk region.Level of knowledge on self-protection measures at threating or actual radioactive pollution of the places of residence appeared a little higher among the Far East region population, who had actual concerns regarding the threat of radioactive pollution at the present time. However, in all eight investigated groups

308-nm excimer laser for the treatment of alopecia areata.

Science.gov (United States)

Al-Mutairi, Nawaf

2007-12-01

Alopecia areata is loss of hair from localized or diffuse areas of hair-bearing area of the skin. Recently there are reports of efficacy of the 308-nm excimer radiation for this condition. To study the effect of the 308-nm excimer laser in the treatment of alopecia areata. Eighteen patients with 42 recalcitrant patches (including 1 adult with alopecia totalis) were enrolled in this study. The lesions were treated with the 308-nm excimer laser twice a week for a period of 12 weeks; one lesion on each patient was left as a control for comparison. There were 7 males and 11 females in this study. Regrowth of hair was observed in 17 (41.5%) patches. Thirteen of the 18 lesions in scalp showed a complete regrowth of hair. The extremity regions failed to show a response. Atopic diatheses had an unfavorable effect on the outcome in our patients. The 308-nm excimer laser is an effective therapeutic option for patchy alopecia areata of the scalp and for some cases with patchy alopecia areata of the beard area. It does not work for patchy alopecia areata of the extremities.

Experience in the development and practical use of working control levels for radiation safety

International Nuclear Information System (INIS)

Epishin, A.V.

1981-01-01

The experience of development and practical use of working control levels (WCL) of radiation safety in the Gorky region, is discussed. WCL are introduced by ''Radiation Safety Guides'' (RSG-76) and have great practical importance. Regional control levels of radiation safety are determined for certain types of operations implying radioactive hazard and differentiated according to the types of sources applied and types of operation. Dose rates, radioactive contamination of operating surfaces, skin, air and waste water are subject to normalization. Limits of individual radiation doses specified according to operation categories are included. 10 tables of regional WCL indices are developed [ru

The Australasian radiation protection society's position statement on risks from low levels of ionizing radiation

International Nuclear Information System (INIS)

Don, Higson; Ches, Mason; Andrew, McEwan; Peter, Burns; Riaz, Akber; Ron, Cameron; Pamela, Sykes; Joe, Young

2006-01-01

At its Annual General Meeting in 2004, the Australasian Radiation Protection Society (A.R.P.S.) set up a working group to draft a statement of the Society's position on risks from low levels of exposure to ionizing radiation. The resulting position statement was adopted by the Society at its Annual General Meeting in 2005. Its salient features are as follows: First, there is insufficient evidence to establish a dose-effect relationship for doses that are less than a few tens of milli sieverts in a year. A linear extrapolation from higher dose levels should be assumed only for the purpose of applying regulatory controls. Secondly, estimates of collective dose arising from individual doses that are less than some tens of milli sieverts in a year should not be used to predict numbers of fatal cancers. Thirdly, the risk to an individual of doses significantly less than 100 micro sieverts in a year is so small, if it exists at all, that regulatory requirements to control exposure at this level are not warranted. (authors)

Simplified calculation of nonlocal thermodynamic equilibrium excited state populations contributing to 13.5 nm emission in a tin plasma

International Nuclear Information System (INIS)

White, J.; Cummings, A.; Dunne, P.; Hayden, P.; O'Sullivan, G.

2007-01-01

Extreme ultraviolet lithography schemes for the semiconductor industry are currently based on coupling radiation from a plasma source into a 2% bandwidth at 13.5 nm (91.8 eV). In this paper, we consider the case for a laser-produced plasma (LPP) and address the calculation of ionic level populations in the 4p 6 4d N , 4p 6 4d N-1 4f 1 , 4p 5 4d N+1 , and 4p 6 4d N-1 5p 1 configurations in a range of tin ions (Sn 6+ to Sn 13+ ) producing radiation in this bandwidth. The LPP is modeled using a one-dimensional hydrodynamics code, which uses a hydrogenic, average atom model, where the level populations are treated as l degenerate. Hartree-Fock calculations are used to remove the l degeneracy and an energy functional method to calculate the nl level populations involved in n=4-4 transitions as a function of distance from the target surface and time. Detailed data are presented for the tin ions that contribute to in-band emission

The hazards of low-level radiation

International Nuclear Information System (INIS)

Blackith, R.

1979-01-01

Safety standards are questioned, particularly in relation to the risk of inducing cancer at low doses of radiation. Statements are made on the following topics: incidence of leukaemia among children around reactors, general aging effect due to radiation, leukaemia among radiation workers in a shipyard repairing nuclear submarines, official withdrawal of funds from research workers in the field of radiation hazards, discrepancies between different measurements of radiation near nuclear power plants. (U.K.)

Operator dependency of the radiation exposure in cardiac interventions: feasibility of ultra low dose levels

International Nuclear Information System (INIS)

Emre Ozpelit, Mehmet; Ercan, Ertugrul; Pekel, Nihat; Tengiz, Istemihan; Yilmaz, Akar; Ozpelit, Ebru; Ozyurtlu, Ferhat

2017-01-01

Introduction: Mean radiation exposure in invasive cardiology varies greatly between different centres and interventionists. The International Commission on Radiological Protection and the EURATOM Council stipulate that, despite reference values, 'All medical exposure for radiodiagnostic purposes shall be kept as low as reasonably achievable' (ALARA). The purpose of this study is to establish the effects of the routine application of ALARA principles and to determine operator and procedure impact on radiation exposure in interventional cardiology. Materials and methods: A total of 240 consecutive cardiac interventional procedures were analysed. Five operators performed the procedures, two of whom were working in accordance with ALARA principles (Group 1 operators) with the remaining three working in a standard manner (Group 2 operators). Radiation exposure levels of these two groups were compared. Results: Total fluoroscopy time and the number of radiographic runs were similar between groups. However, dose area product and cumulative dose were significantly lower in Group 1 when compared with Group 2. Radiation levels of Group 1 were far below even the reference levels in the literature, thus representing an ultra-low-dose radiation exposure in interventional cardiology. Conclusion: By use of simple radiation reducing techniques, ultra-low-dose radiation exposure is feasible in interventional cardiology. Achievability of such levels depends greatly on operator awareness, desire, knowledge and experience of radiation protection. (authors)

1991 implementation of As Low As Reasonably Achievable (ALARA) administrative radiation exposure levels: Experiences and lessons learned

International Nuclear Information System (INIS)

Aldridge, T.L.; Baumann, B.L.

1993-06-01

As Low As Reasonably Achievable (ALARA) radiation exposure levels were implemented on January 1, 1991, by Westinghouse Hanford Company (WHC), a prime US Department of Energy (DOE) contractor, located in Richland, Washington. This paper describes the radiation exposure levels which were implemented and the associated experiences and lessons learned. The issue of a report from the Committee on Biological Effectiveness of Ionizing Radiation in 1989 prompted DOE to re-evaluate its position on radiation exposure limits and the resulting doses received by occupational radiation workers. DOE requested that all it's contractors determine the impacts to operations from reduced radiation exposure levels

Measurement and Modeling of Vertically Resolved Aerosol Optical Properties and Radiative Fluxes Over the ARM SGP Site

Science.gov (United States)

Schmid, B.; Arnott, P.; Bucholtz, A.; Colarco, P.; Covert, D.; Eilers, J.; Elleman, R.; Ferrare, R.; Flagan, R.; Jonsson, H.

2003-01-01

In order to meet one of its goals - to relate observations of radiative fluxes and radiances to the atmospheric composition - the Department of Energy's Atmospheric Radiation Measurement (ARM) program has pursued measurements and modeling activities that attempt to determine how aerosols impact atmospheric radiative transfer, both directly and indirectly. However, significant discrepancies between aerosol properties measured in situ or remotely remain. One of the objectives of the Aerosol Intensive Operational Period (TOP) conducted by ARM in May 2003 at the ARM Southern Great Plains (SGP) site in north central Oklahoma was to examine and hopefully reduce these differences. The IOP involved airborne measurements from two airplanes over the heavily instrumented SGP site. We give an overview of airborne results obtained aboard the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft. The Twin Otter performed 16 research flights over the SGP site. The aircraft carried instrumentation to perform in-situ measurements of aerosol absorption, scattering, extinction and particle size. This included such novel techniques as the photoacoustic and cavity ring-down methods for in-situ absorption (675 nm) and extinction (675 and 1550 nm) and a new multiwavelength, filter-based absorption photometer (467, 530, 660 nm). A newly developed instrument measured cloud condensation nucleus concentration (CCN) concentrations at two supersaturation levels. Aerosol optical depth and extinction (354-2139 nm) were measured with the NASA Ames Airborne Tracking 14-channel sunphotometer. Furthermore, up-and downwelling solar (broadband and spectral) and infrared radiation were measured using seven individual radiometers. Three up-looking radiometers werer mounted on a newly developed stabilized platform, keeping the instruments level up to aircraft pitch and roll angles of approximately 10(exp 0). This resulted in unprecedented continuous vertical profiles

PERCEPTION LEVEL EVALUATION OF RADIO ELECTRONIC MEANS TO A PULSE OF ELECTROMAGNETIC RADIATION

Directory of Open Access Journals (Sweden)

2016-01-01

Full Text Available The method for evaluating the perception level of electronic means to pulsed electromagnetic radiation is consid- ered in this article. The electromagnetic wave penetration mechanism towards the elements of electronic systems and the impact on them are determined by the intensity of the radiation field on the elements of electronic systems. The impact of electromagnetic radiation pulses to the electronic systems refers to physical and analytical parameters of the relationship between exposure to pulses of electromagnetic radiation and the sample parameters of electronic systems. A physical and mathematical model of evaluating the perception level of electronic means to pulsed electromagnetic radiation is given. The developed model was based on the physics of electronics means failure which represents the description of electro- magnetic, electric and thermal processes that lead to the degradation of the original structure of the apparatus elements. The conditions that lead to the total equation electronic systems functional destruction when exposed to electromagnetic radia- tion pulses are described. The internal characteristics of the component elements that respond to the damaging effects are considered. The ratio for the power failure is determined. A thermal breakdown temperature versus pulse duration of expo- sure at various power levels is obtained. The way of evaluation the reliability of electronic systems when exposed to pulses of electromagnetic radiation as a destructive factor is obtained.

Dust Explosion Characteristics of Agglomerated 35 nm and 100 nm Aluminum Particles

Directory of Open Access Journals (Sweden)

Hong-Chun Wu

2010-01-01

Full Text Available In the experiment, nanoparticles of 35 nm Al and 100 nm Al powders, respectively, formed particles with average sizes of 161 nm and 167 nm in agglomeration. The characteristics of dust cloud explosions with the two powder sizes, 35 nm and 100 nm, revealed considerable differences, as shown here: (dp/dtmax-35 nm = 1254 bar/s, (dp/dtmax-100 nm = 1105 bar/s; Pmax-35 nm = 7.5 bar, Pmax-100 nm = 12.3 bar, and MEC-35 nm = 40 g/m3, MEC-100 nm = 50 g/m3. The reason of Pmax-35 nm value is smaller than Pmax-100 nm may be due to agglomeration. From an analysis of the explosive residue, the study found that nanoparticles of 35 nm Al powder became filamentous strands after an explosion, where most of 100 nm Al nanoparticles maintained a spherical structure, This may be because the initial melting temperature of 35 nm Al is 435.71°C, while that for 100 nm Al is 523.58°C, higher by 87.87°C. This study discovered that explosive property between the 35 nm Al and 100 nm Al powders after agglomeration were different.

Level of terrestrial gamma radiation and doses to population in Jiangsu province

International Nuclear Information System (INIS)

1985-01-01

In this paper the results of investigation of terrestrial gamma radiation level in Jiangsu Province are reported and the population doses due to this radiation are estimated. The sketch map of the geographical distribution of the terrestrial gamma radiation level is given. In this investigation FD-71 portable scintillation counters and RSS-111 high pressure ionization chambers were used. The results showed that the terrestrial gamma absorbed dose rates in air for indoors and outdoors were 10.7 x 10 -8 Gy/h and 6.5 x 10 -8 Gy/h (weighted values) respectively. The indoors-to-outdoors ratio was 1.65. The total (indoor plus outdoor) annual effective dose equivalent from terrestrial gamma radiation, averaged over the population in this province, was 6.0 x 10 -4 Sv. The collective annual effective dose equivalent was 3.6 x 10 4 man.Sv. Therefore, the absorbed dose to population in Jiangsu Province is in the range of the normal background

Harmonic Content of the BESSY FEL Radiation

CERN Document Server

Meseck, Atoosa

2005-01-01

BESSY proposes a linac-based cascaded High-Gain Harmonic-Generation (HGHG) free electron laser (FEL) multi-user facility. The BESSY soft X-ray FEL will consist of three undulator lines. The associated tunable lasers will cover the spectral range of 230nm to 460nm. Two to four HGHG stages reduce the seed wavelength to the desired radiation range of 1.24nm < λ < 51nm. The harmonic content of the high-intensity radiator output can be used to reduce the number of necessary HGHG stages. Moreover the higher harmonic content of the final output extends the offered spectral range and thus is of high interest for the user community. In this paper, the higher harmonic content of the final output as well as of the output of several radiators are investigated. The main parameters such as output power, pulse duration and bandwidth as well as their suitability for seeding are discussed.

Radiation-induced bilateral cystic frontal lobe necroses demonstrating a fluid-blood level; Case report

Energy Technology Data Exchange (ETDEWEB)

Mineura, Katsuyoshi; Sasajima, Toshio; Kowada, Masayoshi [Akita Univ. (Japan). School of Medicine; Ogawa, Toshihide

1992-02-01

A 41-year-old male developed radiation-induced bilateral cystic frontal lobe necroses after irradiation for an olfactory neuroblastoma. Computed tomography (CT) and magnetic resonance (MR) imaging revealed the lesions, one containing a fluid-blood level on CT scans and niveau formation on MR images. It was proved to be a coagulated hematoma within the cyst at surgery. Such a fluid-blood level in a radiation-induced cyst has never been reported, although hemorrhage frequently accompanies delayed radiation necrosis. Positron emission tomography with multiple tracers may be useful in differentiating cerebral radiation necrosis from tumor recurrence, because of absence of abnormal tracer accumulation. (author).

Impact of low-level radiation with special reference to tritium in environment

International Nuclear Information System (INIS)

Bhatia, A.L.

2005-01-01

Radiation is invisible, but exists in various types, in the form of particles and/or energy bundles. The effects of low-level radiation seem very abstract since these can not be perceived by our sensory organs. The increase in natural background radiation from various inadvertent sources like tritium has the prospect of altering the entire scenario of billions of years' slow and steady biogenetic evolution. Mankind, by developing atomic technologies, is unleashing forces which it does understand but not beyond experimental findings. There is no wise sorcerer who can undo the damage we are causing. Tritium is a radioactive form of hydrogen that is produced in the reactor core. The released tritium replaces hydrogen in water. Tritium in water when gets ingested, causes continuos internal low-level beta radiation exposure over a long period. Proposed presentation will focus on the possible long term damage caused by its low-level exposure is dependent on the length of duration living tissue spends in the radiation field, not on the relative radiation field strength. As internal radiation pulses never stop, impact is continuous by the ambient radiation atmosphere. There is no chance to heal at the molecular level, except small chances of DNA repair since the organically bound tritium has greater severe influence with the slow turnover. Though the situation needs not be alarming with tritium, the studies on radiation damage on various parameters have given evidence of two compartments of radiation damage; the reparable or potentially lethal and the irreparable or lethal. With emerging new reports on the stochastic effects, those for which the probability, rather than the severity of an effect from tritium occurring as a function of dose also can not be ruled out. Biotoxicity of tritium in the form of induction of cancer, hereditary effects, teratogenesis and life shortening really needs an exhaustive investigation and warrants careful evaluation. However, a positive

Phase-shifted Bragg grating inscription in PMMA microstructured POF using 248 nm UV radiation

DEFF Research Database (Denmark)

Pereira, L.; Pospori, A.; Antunes, Paulo

2017-01-01

In this work we experimentally validate and characterize the first phase-shifted polymer optical fiber Bragg gratings (PS-POFBGs) produced using a single pulse from a 248 nm krypton fluoride laser. A single-mode poly (methyl methacrylate) optical fiber with a core doped with benzyl dimethyl ketal...... for photosensitivity improvement was used. A uniform phase mask customized for 850 nm grating inscription was used to inscribe these Bragg structures. The phase shift defect was created directly during the grating inscription process by placing a narrow blocking aperture in the center of the UV beam. The produced high...

EC-directive optical radiation - present state of consultation; EG-Richtlinie optische Strahlung - aktueller Beratungsstand

Energy Technology Data Exchange (ETDEWEB)

Pipke, R. [Bundesanstalt fuer Arbeitschutz und Arbeitsmedizin, Dortmund (Germany)

2004-07-01

The draft of a directive on the protection of workers from risks related to radiation in the range from 100 nm to 1 mm (Laser, UV-radiation) is discussed on EC-level. The European concept of regulations on occupational safety and health is outlined and put into reference with other directives on the protection against physical agents (vibrations, noise, electromagnetic fields). Building up on this the present state of consultation of a directive on optical radiation is represented, including major points of consideration. (orig.)

The Cd 5 3P0 state in the cadmium-photosensitized reaction and the quenching of the resonance radiation at 326.1 nm by nitrogen, carbon monoxide, and carbon dioxide

International Nuclear Information System (INIS)

Yamamoto, Shunzo; Takaoka, Motoaki; Tsunashima, Shigeru; Sato, Shin

1975-01-01

The emission of the resonance line at 326.1 nm (5 3 P 1 →5 1 S 0 ) and the absorptions of Cd ( 3 P 0 ) at 340.4 nm (5 3 P 0 →5 3 D 1 ) and of Cd ( 3 P 1 ) at 346.6 nm (5 3 P 1 →5 3 D 2 ) have been measured as functions of the pressure of foreign gases at 250 0 C. At the pressures higher than 1 Torr of any rare gas, an equilibrium was established between 5 3 P 1 and 5 3 P 0 states. The efficiency of nitrogen in producing the 5 3 P 0 state from the 5 3 P 1 state was found to be more than 10 3 times those of rare gases. The quenching efficiencies of nitrogen, carbon monoxide, and carbon dioxide for the resonance radiation at 326.1 nm were also measured by using argon as the diluent gas. The half-quenching pressures obtained were 73+-3, 0.47+-0.01, and 0.096+-0.003 Torr for nitrogen, carbon monoxide, and carbon dioxide respectively. (auth.)

The assessment of risks from exposure to low-levels of ionizing radiation

International Nuclear Information System (INIS)

Gilbert, E.S.

1992-06-01

This report is concerned with risk assessments for human populations receiving low level radiation doses; workers routinely exposed to radiation, Japanese victims of nuclear bombs, and the general public are all considered. Topics covered include risk estimates for cancer, mortality rates, risk estimates for nuclear site workers, and dosimetry

Natural radiation external exposures levels in Chilean Sub-Antarctic and country stations

International Nuclear Information System (INIS)

Stuardo, E.

1988-01-01

Since 1983 gamma exposures levels, at 1,5 m above the soil are being investigated using TLD detectors. A network of 12 stations have been established from ARICA (18 deg 20' S latitude) in Northern Chile to YELCHO (64 deg 52' S latitude) in Antartic territory. One year monitoring period was used at Antartic stations and a four months period in the country. The main subject of this study is to assess the average background radiation levels along the territory which is relevant to get a reference level and specially an estimate of the average natural radiation contribution to the population dose in Southern Chile

Ambient radioactivity levels and radiation doses. Annual report 2014; Umweltradioaktivitaet und Strahlenbelastung. Jahresbericht 2014

Energy Technology Data Exchange (ETDEWEB)

Trugenberger-Schnabel, Angela; Loebke-Reinl, Angelika; Peter, Josef (comps.) [Bundesamt fuer Strahlenschutz, Salzgitter (Germany)

2016-08-15

The annual report 2014 on ambient radioactivity levels and radiation doses covers the following topics: (1) Actual data and their evaluation: natural environmental radioactivity, artificial environmental radioactivity, occupational radiation exposure, radiation exposures from medical applications, handling of radioactive materials and sources of ionizing radiation, non-ionizing radiation. (2) Fundamentals and general information: legal basis and explanations, basic information on natural environmental radioactivity, basic information on artificial radioactivity in the environment, basic information on occupational radiation exposure, basic information on radiation exposures from medical applications, basic information on the handling of radioactive materials and sources of ionizing radiation, basic information on non-ionizing radiation. (3) Tables.

High level natural radiation areas with special regard to Ramsar

International Nuclear Information System (INIS)

Sohrabi, M.

1993-01-01

The studies of high level natural radiation areas (HLNRAs) around the world are of great importance for determination of risks due to long-term low-level whole body exposures of public. Many areas of the world possess HLNRAs the number of which depends on the criteria defined. Detailed radiological studies have been carried out in some HLNRAs the results of which have been reported at least in three international conferences. Among the HLNRAs, Ramsar has so far the highest level of natural radiation in some areas where radiological studies have been of concern. A program was established for Ramsar and its HLNRAs to study indoor and outdoor gamma exposures and external and internal doses of the inhabitants, 226 Ra content of public water supplies and hot springs, of food stuffs, etc., 222 Rn levels measured in 473 rooms of near 350 houses, 16 schools and 89 rooms and many locations of old and new Ramsar Hotels in different seasons, cytogenetic effects on inhabitants of Talesh Mahalleh, the highest radiation area, compared to that of a control area and radiological parameters of a house with a high potential for internal and external exposures of the inhabitants. It was concluded that the epidemiological studies in a number of countries did not show any evidence of increased health detriment in HLNRAs compared to control groups. In this paper, the conclusions drawn from studies in some HLNRAs around the world in particular Ramsar are discussed. (author). 20 refs, 2 figs, 1 tab

Ramsar hot springs: how safe is to live in an environment with high level of natural radiation

International Nuclear Information System (INIS)

Mortazavi, S.M.J.

2005-01-01

Ramsar in northern Iran is among the world's well-known areas with highest levels of natural radiation. Annual exposure levels in areas with elevated levels of natural radiation in Ramsar are up to 260 mGy y -1 and average exposure rates are about 10 mGy y -1 for a population of about 2000 residents. Due to the local geology, which includes high levels of radium in rocks, soils, and groundwater, Ramsar residents are also exposed to high levels of alpha activity in the form of ingested radium and radium decay progeny as well as very high radon levels (over 1000 MBq m -3 ) in their dwellings. In some cases, the inhabitants of these areas receive doses much higher than the current ICRP-60 dose limit of 20 mSv y -1 . As the biological effects of low doses of radiation are not fully understood, the current radiation protection recommendations are based on the predictions of an assumption on the linear, no-threshold (LNT) relationship between radiation dose and the carcinogenic effects. Considering LNT, areas having such levels of natural radiation must be evacuated or at least require immediate remedial actions. Inhabitants of the high level natural radiation areas (HLNRAs) of Ramsar ar largely unaware of natural radiation, radon, or its possible health effects, and the inhabitants have not encountered any harmful effects due to living in their paternal houses. In this regard, it is often difficult to ask the inhabitants of HLNRAs of Ramsar to carry out remedical actions. Despite the fact that considering LNT and ALARA, public health in HLNRAs like Ramsar is best served by relocating the inhabitants, the residents' health seems unaffected and relocation is upsetting to the residents. Based on the findings obtained by studies on the health effect of high levels of natural radiation in Ramsar, as well as other HLNRAs, no consistent detrimental effect has been detected so far. However, more research is needed to clarify if the regulatory authorities should set limiting

Effects of ultraviolet-B radiation (UV-B) on growth and physiology of the dune grassland species Calamagrostis epigeios

International Nuclear Information System (INIS)

Tosserams, M.; Rozema, J.

1995-01-01

Seedlings of Calamagrostis epigeios were exposed to four levels of UV-B radiation (280-320 nm), simulating up to 44% reduction of stratospheric ozone concentration during summertime in The Netherlands, to determine the response of this plant species to UV-B irradiation. After six weeks of UV-B treatment, total biomass of all UV-B treated plants was higher, compared to plants that had received no UV-B radiation. The increase of biomass did not appear to be the result of a stimulation of net photosynthesis. Also, transpiration rate and water use efficiency were not altered by UV-B at any exposure level. Pigment analysis of leaf extracts showed no effect of enhanced UV-B radiation on chlorophyll content and accumulation of UV absorbing pigments. UV-B irradiance, however, did reduce the transmittance of visible light (400-700 nm) of intact attached leaves, suggesting a change in anatomical characteristics of the leaves. Additionally, the importance of including an ambient UV-B treatment in indoor experiments is discussed

Effectiveness of eye drops protective against ultraviolet radiation.

Science.gov (United States)

Daxer, A; Blumthaler, M; Schreder, J; Ettl, A

1998-01-01

To test the effectiveness of commercially available ultraviolet (UV)-protective eye drops (8-hydroxy-1-methylchinolinium methylsulphate) which are recommended for protection against both solar and artificial UV radiation. The spectral transmission in the wavelength range from 250 to 500 nm was investigated in 1-nm steps using a high-resolution double monochromator with holographic gratings of 2,400 lines/mm and a 1,000-watt halogen lamp as light source. The transmission spectrum was measured for different values of the layer thickness. The transmission of a liquid layer of about 10 microns, which corresponds to the thickness of the human tear film, shows a cut-off at 290 nm with a transmission of about 25-50% at shorter wavelengths. For wavelengths longer than 290 nm the transmission is higher than 90%. The threshold time ratio for keratitis formation with and without eye drops is above 0.93 considering solar radiation on the earth's surface and above 0.65 considering radiation from arc-welding, respectively. The transmission spectrum of the eye drops under realistic conditions does not show a protective effect against solar UV radiation. However, there exists reduction of UVC radiation in the spectral range typical of artificial UV sources such as arc-welding. We cannot recommend the application of these eye drops as an UV-protective aid against eye damage by solar UV radiation.

Investigation on the acceptance level of radiation exposure. Comparison of Chinese and Japanese

International Nuclear Information System (INIS)

Wu, Jin; Katoh, Kazuaki

1999-01-01

Radiation has helped to develop our culture and civilization, both of material and of spiritual, and without doubt it is useful to develop our civilization further and to enrich our future life. On the other hand, we cannot help avoiding to live with some by-product radiation of 'advanced civilization' in addition. Thus we must associate with radiation even if we like it or not. To our understanding, safety standard or criteria of safety control is nothing but a contract of the body concerned with the society. In order to make this contract rigorously, it is required for both sides to have adequately enough knowledge and data on the methodology of treating the matter. In such societies, people's acceptable levels to radiation exposure would not be widely distributed. Unification of the wills of the society is absolutely necessary to establish such a contact or develop the philosophy on radiation safety. Hence, we have tried to investigate the acceptable levels of people to radiation exposure. Two kinds of levels, upper limit of the acceptable dose for instantaneous whole body exposure, Lu, and lowest of the dose caring in mind, Ll, were set for inquiry. In this presentation, some results of our survey to both Chinese and Japanese professionals in the fields of science-technology and medical science are reported. Similarly to the previous study by Katoh, in 1989 or so, the distribution of these two levels were very broad and the band widths between the two levels, Lu and Ll, were quite narrow. The former seems reveal the variety of individual's sense of value. Moreover, it was found that, two levels, Lu and Ll, were significantly higher (p<0.05, p<0.005) in Japanese to in Chinese in science/engineering group, while in medical group, the two levels were higher apparently in Japanese than in Chinese, but no statistically significant difference was observed. Moreover, in medical group, Lu and Ll showed higher values than those in science-technology group for the

Radiation sources, radiation environment and risk level at Dubna

International Nuclear Information System (INIS)

Komochkov, M.M.

1991-01-01

The overall information about ionizing radiation sources, which form radiation environment and risk at Dubna, is introduced. Systematization of the measurement results is performed on the basis of the effective dose and losses of life expectancy. The contribution of different sources to total harm of Dubna inhabitants has been revealed. JINR sources carry in ∼ 4% from the total effective dose of natural and medicine radiation sources; the harm from them is much less than the harm from cigarette smoking. 18 refs.; 2 tabs

Legal aspects of radiation protection at the international level

International Nuclear Information System (INIS)

Papazian, J.

1981-01-01

A review is made of the respective activities of the various international organizations concerned with radiation protection at the legal level. These organizations are either non-governmental (I.C.R.P., I.C.R.U.) or governmental in which case they can act at the world (U.N., I.A.E.A., I.L.O., W.H.O.) or regional level (N.E.A., EURATOM, COMECOM). The legal impact of the recommendations or directives they issue is specified [fr

Absolutely calibrated vacuum ultraviolet spectra in the 150-250-nm range from plasmas generated by the NIKE KrF laser

International Nuclear Information System (INIS)

Seely, J.F.; Feldman, Uri; Holland, G.E.; Weaver, J.L.; Mostovych, A.N.; Obenschain, S.P.; Schmitt, A.J.; Lehmberg, R.; Kjornarattanawanich, Benjawan; Back, C.A.

2005-01-01

High-resolution vacuum ultraviolet (VUV) spectra were recorded from plasmas generated by the NIKE KrF laser for the purpose of observing emission from the two-plasmon decay instability (TPDI) at 2/3 the NIKE wavelength (165 nm). The targets were irradiated by up to 43 overlapping beams with intensity up to ≅10 14 W/cm 2 and with beam smoothing by induced spatial incoherence (ISI). The targets consisted of planar foils of CH, BN, Al, Si, S, Ti, Pd, and Au. Titanium-doped silica aerogels in Pyrex cylinders were also irradiated. The spectra of the target elements were observed from charge states ranging from the neutral atoms to five times ionized. The spectrometer was absolutely calibrated using synchrotron radiation, and absolute VUV plasma emission intensities were determined. Emission from the TPDI at 165-nm wavelength was not observed from any of the irradiated targets. An upper bound on the possible TPDI emission was less than 4x10 -8 the incident NIKE laser energy. The NIKE laser radiation backscattered from the silica aerogel targets at 248 nm was typically 6x10 -6 the incident NIKE laser energy, and the spectral broadening corresponded to the 1-THz bandwidth of the ISI smoothing. The spectra from the moderately charged plasma ions (up to five times ionized), spectral linewidths, absolute continuum emission level, and slope of the continuum were consistent with plasma temperatures in the 100-300-eV range

Mitotic effects of monochromatic ultraviolet radiation at 225, 265, and 280 nm on eleven stages of the cell cycle of the grasshopper neuroblast in culture. I. Overall retardation from the stage irradiated to nuclear membrane breakdown

International Nuclear Information System (INIS)

Carlson, J.G.

1976-01-01

Neuroblasts of Chortophaga viridifasciata (DeGeer) in culture were exposed to different doses of 225, 265, or 280 nm ultraviolet radiations at 11 different stages and substages of the mitotic cycle and individually selected cells were timed to breakdown of the nuclear membrane. Comparisons of the effectiveness of different wavelengths on the different stages were based on the dose that reduced the cell progression rate to 67 percent of normal (D 67 ) and the slope of the regression line, i.e., the control to treated time (C/T) ratio change/erg/mm 2 at the D 67 level. Cells of the prereplication period (metaphase + anaphase + early telophase) and the S phase (middle and late telophase + interphase + very early prophase) are equally sensitive to uv and contrast sharply with the much lower sensitivity of those in the postreplication period (early and middle prophase). This can best be interpreted if chromosomal DNA is the chromophore for uv-induced mitotic retardation. Cells in the prereplication period at exposure show no wavelength effect. In the S phase all stages except middle telophase and all stages combined are significantly more sensitive to 265 and 280 nm than to 225 nm. Of the postreplication stages, early prophase is retarded significantly more by 280 than by 225 or 265 nm. The C/T ratio/erg/mm 2 is greater after exposure to 265 nm at all prereplication and replication stages, but exhibits no consistent wavelength pattern during the postreplication period. Evidence based on the orientation of the neuroblast with respect to the uv-source suggests that the chromophore for mitotic retardation does not reside within the centrosome and related structures, but may be present, at least partly, in the nucleolus

Radiation therapists' perceptions of the minimum level of experience required to perform portal image analysis

International Nuclear Information System (INIS)

Rybovic, Michala; Halkett, Georgia K.; Banati, Richard B.; Cox, Jennifer

2008-01-01

Background and purpose: Our aim was to explore radiation therapists' views on the level of experience necessary to undertake portal image analysis and clinical decision making. Materials and methods: A questionnaire was developed to determine the availability of portal imaging equipment in Australia and New Zealand. We analysed radiation therapists' responses to a specific question regarding their opinion on the minimum level of experience required for health professionals to analyse portal images. We used grounded theory and a constant comparative method of data analysis to derive the main themes. Results: Forty-six radiation oncology facilities were represented in our survey, with 40 questionnaires being returned (87%). Thirty-seven radiation therapists answered our free-text question. Radiation therapists indicated three main themes which they felt were important in determining the minimum level of experience: 'gaining on-the-job experience', 'receiving training' and 'working as a team'. Conclusions: Radiation therapists indicated that competence in portal image review occurs via various learning mechanisms. Further research is warranted to determine perspectives of other health professionals, such as radiation oncologists, on portal image review becoming part of radiation therapists' extended role. Suitable training programs and steps for implementation should be developed to facilitate this endeavour

Discrete level schemes and their gamma radiation branching ratios (CENPL-DLS). Pt. 1

International Nuclear Information System (INIS)

Su Zongdi; Zhang Limin; Zhou Chunmei; Sun Zhengjun

1994-01-01

The DLS data file, which is a sub-library (version 1) of Chinese Evaluated Nuclear Parameter Library (CENPL), consists of data and information of discrete levels and gamma radiations. The data and information of this data file are translated from the Evaluated Nuclear Structure Data File (ENSDF). The transforming code from ENSDF to DLS was written. In the DLS data file, there are the data on discrete levels with determinate energy and their gamma radiations. At present, this file contains the data of 79456 levels and 100411 gammas for 1908 nuclides

Radiation exposure rate and liquid level measurement inside a high level liquid waste (HLLW) storage tank

International Nuclear Information System (INIS)

Sur, B.; Yue, S.; Thekkevarriam, A.

2007-01-01

An instrument based on an inexpensive, small silicon diode has been developed and used to measure, for the first time, the gamma radiation exposure rate profile inside a 6.4 mm diameter reentrant thermo-well tube, immersed in the highly radioactive liquid solution in an HLLW storage tank. The measurement agrees with previous calculations of exposure rate, and provides confirmation for safe and effective radiation work plans and material selection for investigations and remediation of the storage tank facility. The measured radiation exposure rate profile is also used to confirm that the position of tank internal structures have not changed because of aging and corrosion, and to obtain, within a few mm, the level of liquid inside the tank. (author)

Infrared Radiative Properties of Food Materials

Science.gov (United States)

Precisely, infrared radiation is electromagnetic radiation whose wavelength is longer than that of visible light, but shorter than that of terahertz radiation and microwaves. The infrared portion of the electromagnetic spectrum spans roughly three orders of magnitude (750 nm to 100 µm) and has been...

Temperature dependence of the photodissociation of CO2 from high vibrational levels: 205-230 nm imaging studies of CO(X1Σ+) and O(3P, 1D) products

Science.gov (United States)

Sutradhar, S.; Samanta, B. R.; Samanta, A. K.; Reisler, H.

2017-07-01

The 205-230 nm photodissociation of vibrationally excited CO2 at temperatures up to 1800 K was studied using Resonance Enhanced Multiphoton Ionization (REMPI) and time-sliced Velocity Map Imaging (VMI). CO2 molecules seeded in He were heated in an SiC tube attached to a pulsed valve and supersonically expanded to create a molecular beam of rotationally cooled but vibrationally hot CO2. Photodissociation was observed from vibrationally excited CO2 with internal energies up to about 20 000 cm-1, and CO(X1Σ+), O(3P), and O(1D) products were detected by REMPI. The large enhancement in the absorption cross section with increasing CO2 vibrational excitation made this investigation feasible. The internal energies of heated CO2 molecules that absorbed 230 nm radiation were estimated from the kinetic energy release (KER) distributions of CO(X1Σ+) products in v″ = 0. At 230 nm, CO2 needs to have at least 4000 cm-1 of rovibrational energy to absorb the UV radiation and produce CO(X1Σ+) + O(3P). CO2 internal energies in excess of 16 000 cm-1 were confirmed by observing O(1D) products. It is likely that initial absorption from levels with high bending excitation accesses both the A1B2 and B1A2 states, explaining the nearly isotropic angular distributions of the products. CO(X1Σ+) product internal energies were estimated from REMPI spectroscopy, and the KER distributions of the CO(X1Σ+), O(3P), and O(1D) products were obtained by VMI. The CO product internal energy distributions change with increasing CO2 temperature, suggesting that more than one dynamical pathway is involved when the internal energy of CO2 (and the corresponding available energy) increases. The KER distributions of O(1D) and O(3P) show broad internal energy distributions in the CO(X1Σ+) cofragment, extending up to the maximum allowed by energy but peaking at low KER values. Although not all the observations can be explained at this time, with the aid of available theoretical studies of CO2 VUV

Health effects of low-level radiation in shipyard workers. Final report: [Draft

Energy Technology Data Exchange (ETDEWEB)

Matanoski, G.M.

1991-06-01

The Nuclear Shipyard Workers Study (NSWS) was designed to determine whether there is an excess risk of leukemia or other cancers associated with exposure to low levels of gamma radiation. The study compares the mortality experience of shipyard workers who qualified to work in radiation areas to the mortality of similar workers who hold the same types of jobs but who are not authorized to work in radiation areas. The population consists of workers from six government and two private shipyards.

Linear devices in combined high-level radiation environments

International Nuclear Information System (INIS)

van Vonno, N.W.

1987-01-01

The design of precision analog integrated circuits for use in combined high-level radiation environments has traditionally been on a full-custom basis. The use of semicustom design methods has become prevalent in digital devices, with standard cell libraries and gate arrays readily available from multiple vendors. This paper addresses the application of semicustom design techniques to analog parts. In all cases the emphasis is on bipolar technology, since this provides an optimal combination of precision and radiation hardness. A mixed mode analog/digital (A/D) cell family for implementing semicustom designs is described, together with the fabrication process used. Specific processing and design methods are used to provide circuit hardness against neutron, total gamma dose, and transient gamma environments. Semicustom mixed analog/digital design is seen as an appropriate methodology for implementation of medium-performance mixed mode functions for radiation-hardened applications. This leads to trade-offs in process complexity and performance. Full custom design remains necessary for demanding applications such as high-speed A/D conversion and associated sample/hold functions. An A/D cell family optimized for hardness is described, together with the bipolar process used to implement it

Energy levels, lifetimes and radiative data of W LV

Science.gov (United States)

Ding, Xiao-bin; Sun, Rui; Koike, Fumihiro; Murakami, Izumi; Kato, Daiji; Sakaue, Hiroyuki A.; Nakamura, Nobuyuki; Dong, Chen-zhong

2018-01-01

Calculations of energy levels, radiative data and lifetimes are reported for tungsten Ca-like ion (W LV) by using multi-configuration Dirac-Fock (MCDF) method. The GRASP2K package is adopted to carry out a large-scale systematic computation with a restricted active space treatment; the Breit interaction and QED effects are included in subsequent relativistic configuration interaction calculations. The energies and lifetimes of the lowest 119 levels are listed; the main leading configuration of the levels is of the ground state configuration [Ne]3s23p63d2 and the first excited configuration [Ne]3s23p53d3. The wavelengths, radiative rates and oscillator strengths for relatively strong E1, E2, M1, and M2 transitions are listed. Comparisons with earlier experimental and theoretical values are made. The average relative deviations of energy levels from the NIST results and E1 transition wavelengths from the EBIT experimental results have turned to be only 0.20% and 0.13%, respectively. The other present results are in reasonable agreement with available data. These agreements confirm the reliability and accuracy of the current results. The present datasets may help us with the investigation of the electron-electron correlation effects in complex multi-electron highly charged heavy ions and of the diagnosis of tungsten impurity plasmas in fusion science.

Energy levels and radiative rates for transitions in Ti VI

International Nuclear Information System (INIS)

Aggarwal, K M; Keenan, F P; Msezane, A Z

2013-01-01

We report on calculations of energy levels, radiative rates, oscillator strengths and line strengths for transitions among the lowest 253 levels of the (1s 2 2s 2 2p 6 ) 3s 2 3p 5 , 3s3p 6 , 3s 2 3p 4 3d, 3s3p 5 3d, 3s 2 3p 3 3d 2 , 3s 2 3p 4 4s, 3s 2 3p 4 4p and 3s 2 3p 4 4d configurations of Ti VI. The general-purpose relativistic atomic structure package and flexible atomic code are adopted for the calculations. Radiative rates, oscillator strengths and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2) and magnetic quadrupole (M2) transitions among the 253 levels, although calculations have been performed for a much larger number of levels. Comparisons are made with existing available results and the accuracy of the data is assessed. Additionally, lifetimes for all 253 levels are listed, although comparisons with other theoretical results are limited to only 88 levels. Our energy levels are estimated to be accurate to better than 1% (within 0.03 Ryd), whereas results for other parameters are probably accurate to better than 20%. A reassessment of the energy level data on the National Institute of Standards and Technology website for Ti VI is suggested. (paper)

Effects of chronic low level radiation in the population residing in the high level natural radiation area in Kerala, India: employing heritable DNA mutation studies.

Science.gov (United States)

Ahmad, Shazia; Koya, P K M; Seshadri, M

2013-03-18

To study the effect of chronic low level radiation, 4040 meiosis were screened at eight microsatellite and five minisatellite (2485 and 1555 meiosis respectively) marker loci in people residing in high and normal level natural radiation areas of Kerala. Variants in the repeat length of allele were considered as mutants. Mutation rates (expressed as the number of mutations observed in the total number of meiosis) were 6.4×10(-3) (16/2485) and 2.6×10(-3) (4/1555) at microsatellite and minisatellite respectively. The germline microsatellite mutation frequency of father was 1.78 times higher at 7.52×10(-3) (8/1064) compared to 4.22×10(-3) (6/1421) of mother (P=0.292, Fisher's Exact two-sided test). The paternal and maternal mutation rates at minisatellite loci were more or less similar at 2.78×10(-3) (2/719) and 2.39×10(-3) (2/836), respectively (P=1.0, Fisher's Exact two-sided test). Higher but statistically non-significant microsatellite mutation frequency was observed in HLNRA compared to NLNRA (7.25×10(-3) vs 3.64×10(-3); P=0.547). The apparent increase in the mutation rate of microsatellite loci with the increase in radiation dose was also not statistically significant. All the four minisatellite mutation observed were from HLNRA (1198 meiosis) and no mutation was observed among 357 meiosis screened from NLNRA families. All the markers used in the present study were in the non-coding region and hence mutations in these regions may not cause adverse health effects, but the study is important in understanding the effect of chronic low level radiation. Copyright © 2012 Elsevier B.V. All rights reserved.

Nitrogen deficiency detection using reflected shortwave radiation from irrigated corn canopies

International Nuclear Information System (INIS)

Blackmer, T.M.; Schepers, J.S.; Varvel, G.E.; Walter-Shea, E.A.

1996-01-01

Techniques that measure the N status of corn (Zea mays L.) can aid in management decisions that have economic and environmental implications. This study was conducted to identify reflected electromagnetic wavelengths most sensitive to detecting N deficiencies in a corn canopy with the possibility for use as a management tool. Reflected shortwave radiation was measured from an irrigated corn N response trial with four hybrids and five N rates at 0, 40, 80, 120, and 160 kg N ha -1 in 1992 and 0, 50, 100, 150, and 200 kg N ha -1 in 1993. A portable spectroradiometer was used to measure reflected radiation (400-1100 nm in 1992, 350-1050 nm in 1993) from corn canopies at approximately the R5 growth stage. Regression analyses revealed that reflected radiation near 550 and 710 nm was superior to reflected radiation near 450 or 650 nm for detecting N deficiencies. The ratio of light reflectance between 550 and 600 nm to light reflectance between 800 and 900 nm also provided sensitive detection of N stress. In 1993, an inexpensive photometric cell, which has peak sensitivity to light centered at 550 nm, was also used to measure reflected radiation from a corn canopy. Photometric cell readings correlated with relative grain yield (P < 0.001, r 2 = 0.74), but more research will be required to develop procedures to account for varying daylight conditions. These results provide information needed for the development of variable-rate fertilizer N application technology. (author)

Ultraviolet-B and photosynthetically active radiation interactively affect yield and pattern of monoterpenes in leaves of peppermint (Mentha x piperita L.).

Science.gov (United States)

Behn, Helen; Albert, Andreas; Marx, Friedhelm; Noga, Georg; Ulbrich, Andreas

2010-06-23

Solar radiation is a key environmental signal in regulation of plant secondary metabolism. Since metabolic responses to light and ultraviolet (UV) radiation exposure are known to depend on the ratio of spectral ranges (e.g., UV-B/PAR), we examined effects of different UV-B radiation (280-315 nm) and photosynthetically active radiation (PAR, 400-700 nm) levels and ratios on yield and pattern of monoterpenoid essential oil of peppermint. Experiments were performed in exposure chambers, technically equipped for realistic simulation of natural climate and radiation. The experimental design comprised four irradiation regimes created by the combination of two PAR levels including or excluding UV-B radiation. During flowering, the highest essential oil yield was achieved at high PAR (1150 micromol m(-2) s(-1)) and approximate ambient UV-B radiation (0.6 W m(-2)). Regarding the monoterpene pattern, low PAR (550 micromol m(-2) s(-1)) and the absence of UV-B radiation led to reduced menthol and increased menthone contents and thereby to a substantial decrease in oil quality. Essential oil yield could not be correlated with density or diameter of peltate glandular trichomes, the epidermal structures specialized on biosynthesis, and the accumulation of monoterpenes. The present results lead to the conclusion that production of high quality oils (fulfilling the requirements of the Pharmacopoeia Europaea) requires high levels of natural sunlight. In protected cultivation, the use of UV-B transmitting covering materials is therefore highly recommended.

Efficient quasi-three-level Nd:YAG laser at 946 nm pumped by a tunable external cavity tapered diode laser

DEFF Research Database (Denmark)

Cheng, Haynes Pak Hay; Jensen, Ole Bjarlin; Tidemand-Lichtenberg, Peter

2010-01-01

Using a tunable external cavity tapered diode laser (ECDL) pumped quasi-three-level Nd:YAG laser, a fivefold reduction in threshold and twofold increase in slope efficiency is demonstrated when compared to a traditional broad area diode laser pump source. A TEM00 power of 800 mW with 65% slope...... efficiency is obtained, the highest reported TEM00 power from any 946 nm Nd:YAG laser pumped by a single emitter diode laser pump source. A quantum efficiency of 0.85 has been estimated from experimental data using a simple quasi-three-level model. The reported value is in good agreement with published...

Q-switched Nd:YAG/V:YAG microchip 1338 nm laser for laser-induced breakdown spectroscopy

Science.gov (United States)

Šulc, Jan; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

2017-12-01

Q-switched microchip laser emitting radiation at wavelength 1338nm was tested as a radiation source for laser induced breakdown spectroscopy (LIBS). This laser used sandwich crystal which combined in one piece the cooling part (undoped YAG crystal 4mm long), the active laser part (Nd:YAG crystal 12mm long), and the saturable absorber (V:YAG crystal 0.7mm long). The diameter of this crystal was 5 mm. The microchip resonator consisted of dielectric mirrors directly deposited on the monolith crystal surfaces. The pump mirror (HT @ 808 nm, HR @ 1.3 ¹m) was placed on the undoped YAG part. The output coupler (R = 90% @ 1338 nm) was placed on the V:YAG part. The fibre-coupled 808nm pumping laser diode was operating in pulsed regime (rep. rate 250 Hz, pulse width 300 ¹s, pulse energy 6 mJ). Using this pumping, stable and high reproducible Q-switched pulses were generated at wavelength 1338 nm. Pulse length was 6.2 ns (FWHM) and the mean output power was 33mW. The single pulse energy and peak power was 0.13mJ and 21kW, respectively. Laser was operating in fundamental TEM00 mode. The laser radiation was focused on a tested sample using single plano-convex lens (focal length 75 mm). The focal spot radius was 40 ¹m. The corresponding peak-power density was 0.83GW/cm2. The laser induced break-down was successfully reached and corresponding laser-induced plasma spectra were recorded for set of metallic elements (Cu, Ag, Au, In, Zn, Al, Fe, Ni, Cr) and alloys (Sn-Pb solder, duralumin, stainless-steel, brass). To record the spectra, StellarNet BLACK-Comet concave grating CCD-based spectrometer was used without any special collimation optics. Thanks to used laser wavelength far from the detector sensitivity, no special filtering was needed to overcome the CCD dazzling. The constructed laser could significantly improve repletion-rate of up-to-date LIBS devices.

Effect of 940 nm low-level laser therapy on osteogenesis in vitro

Science.gov (United States)

Jawad, Mohammed Mahmood; Husein, Adam; Azlina, Ahmad; Alam, Mohammad Khursheed; Hassan, Rozita; Shaari, Rumaizi

2013-12-01

Bone regeneration is essential in medical treatment, such as in surgical bone healing and orthodontics. The aim of this study is to examine the effect of different powers of 940 nm diode low-level laser treatment (LLLT) on osteoblast cells during their proliferation and differentiation stages. A human fetal osteoblast cell line was cultured and treated with LLLT. The cells were divided into experimental groups according to the power delivered and periods of exposure per day for each laser power. The (3-(4,5-dimethylthiazol-2yl)-2,5 diphenyl tetrazolium bromide) (MTT) assay was used to determine cell proliferation. Both alkaline phosphatase and osteocalcin activity assays were assessed for cell differentiation. All treatment groups showed a significant increase in cell proliferation and differentiation compared to the control group. Regarding the exposure time, the subgroups treated with the LLLT for 6 min showed higher proliferation and differentiation rates for the powers delivered, the 300-mW LLLT group significantly increased the amount of cell proliferation. By contrast, the 100 and 200 mW groups showed significantly greater amounts of cell differentiation. These results suggest that the use of LLLT may play an important role in stimulating osteoblast cells for improved bone formation.

403 nm cavity ring-down measurements of brown carbon aerosol

Science.gov (United States)

Kwon, D.; Grassian, V. H.; Kleiber, P.; Young, M. A.

2017-12-01

Atmospheric aerosol influences Earth's climate by absorbing and scattering incoming solar radiation and outgoing terrestrial radiation. One class of secondary organic aerosol (SOA), called brown carbon (BrC), has attracted attention for its wavelength dependent light absorbing properties with absorption coefficients that generally increase from the visible (Vis) to ultraviolet (UV) regions. Here we report results from our investigation of the optical properties of BrC aerosol products from the aqueous phase reaction of ammonium sulfate (AS) with methylglyoxal (MG) using cavity ring-down spectroscopy (CRDS) at 403 nm wavelength. We have measured the optical constants of BrC SOA from the AS/MG reaction as a function of reaction time. Under dry flow conditions, we observed no apparent variation in the BrC refractive index with aging over the course of 22 days. The retrieved BrC optical constants are similar to those of AS with n = 1.52 for the real component. Despite significant UV absorption observed from the bulk BrC solution, the imaginary index value at 403 nm is below our minimum detection limit which puts an upper bound of k as 0.03. These observations are in agreement with results from our recent studies of the light scattering properties of this BrC aerosol.

The development needs of nuclear medicine (NM) in Finland in 1980-84

International Nuclear Information System (INIS)

Vauramo, E.; Ahonen, A.; Korkola, O.; Liewendahl, K.; Laensimies, E.; Nyyssoenen, O.; Pietilae, P.; Tervo-Pellikka, R.; Wendelin, H.

1980-01-01

In autumn 1978, a task group was set up by the Finnish Hospital League to investigate the development needs of nuclear medicine (NM) in Finland. Clinical chemistry, clinical physiology, diagnostic radiology and hospital physics were represented on the working group. The National Board of Health, the Institute of Radiation Protection and the Finnish Hospital League were also represented. The views of other fields were considered by asking for statements from hospitals, research institutes and medical associations. This report deals with NM procedures on patients. Sample studies (in vitro) belong to the clinical laboratory and they were dealt with only to a minor extent. (orig.) [de

375-nm ultraviolet-laser based non-line-of-sight underwater optical communication

KAUST Repository

Sun, Xiaobin

2018-05-04

For circumventing the alignment requirement of line-of-sight (LOS) underwater wireless optical communication (UWOC), we demonstrated a non-line-of-sight (NLOS) UWOC link adequately enhanced using ultraviolet (UV) 375-nm laser. Path loss was chosen as a figure-of-merit for link performance in this investigation, which considers the effects of geometries, water turbidity, and transmission wavelength. The experiments suggest that path loss decreases with smaller azimuth angles, higher water turbidity, and shorter wavelength due in part to enhanced scattering utilizing 375-nm radiation. We highlighted that it is feasible to extend the current findings for long distance NLOS UWOC link in turbid water, such as harbor water.

A guide to radiation and radioactivity levels near high energy particle accelerators

International Nuclear Information System (INIS)

Sullivan, A.H.

1992-01-01

An estimate of likely radiation and radioactivity levels is needed at the design stage of an accelerator for deciding the radiation safety features to be incorporated in the infrastructure of the machine and for predicting where radiation damage possibilities will have to be taken into account. Both these aspects can have a significant influence on the machine layout and cost. Failure to make a reasonable assessment at the right time may have far reaching consequences for future costs. The purpose of this guide is to bring together basic data and methods that have been found useful in assessing radiation situations around accelerators and to provide a practical means of arriving at the radiation and induced radioactivity levels that could occur under a wide variety of circumstances. An attempt is made to present the information in a direct and unambiguous way with sufficient confidence that the necessity for large safety factors is avoided. In many cases assumptions and simplifications have been made and reliance placed on extrapolating from experimental data into regions where the basic physics is too complicated to make meaningful absolute calculations. Wherever possible such extrapolations have been tied to real or otherwise acceptable data originating from independent sources. (Author)

Investigation of environmental natural penetrating radiation level in Beijing

International Nuclear Information System (INIS)

Wu Zengxin; Zhang Wenying; Zheng Rukuan; Wei Shujun; Ding Huiqiu

1992-01-01

The authors report the methods and results of investigation of environmental natural penetrating radiation level in Beijing. There were 83 measurement points selected, which were located at the vertexes of 1 x 1 km square meshes and uniformly distributed over the urban district. 173 net grid measuring points selected with grid spacing of 10 x 10 km and uniformly distributed over the suburban district. Another 131 more densely distributed points were added over some special areas. The results show that: (1) The point-weighted, area-weighted and population-weighted average value of natural γ radiation dose rate over field is 56.2, 56.4 and 50.1 nGy · h -1 respectively. The γ radiation dose rate is higher in west and north area than in southeast area. (2) The point-weighted average value of natural γ radiation dose rate over roads was 49.3 nGy · h -1 . (3) The point weighted and population-weighted average value of natural γ radiation dose inside buildings was 83.5 and 77.1 nGy · h -1 respectively. (4) The weighted average of air absorbed dose rate from the ionizing components of cosmic rays (except for neutron) over point number and population was respectively 29.0 and 27.5 nGy · h -1 indoors, and 32.3 and 30.8 nGy · h -1 outdoors. (5) The point and population-weighted means of natural penetrating radiation dose rate (the contribution from neutron is not included) are 112.8 and 104.5 nGy · h -1 indoors, respectively; 88.7 and 81.3 nGy · h -1 outdoors, respectively. (6) The annual effective dose equivalent per capital people natural γ radiation, cosmic ray and natural penetrating radiation was 0.43, 0.25 and 0.68 mSv respectively, and the annual collective effective dose equivalent was 4.0, 2.3 and 6.3 x 10 3 man · Sv, respectively

CW light sources at the 589 nm sodium D2 line by sum-frequency mixing of diode pumped neodymium lasers

International Nuclear Information System (INIS)

Lü, Y F; Lu, J; Xu, L J; Sun, G C; Zhao, Z M; Gao, X; Lin, J Q

2010-01-01

We present a laser architecture to obtain continuous-wave (CW) light sources at the 589 nm sodium D2 line. A 808 nm diode-pumped a Nd:YLiF 4 (Nd:YLF) crystal emitting at 1053 nm. A part of the pump power was then absorbed by the Nd:YLF crystal. The remaining was used to pump a Nd:YAG crystal emitting at 1338 nm. Intracavity sum-frequency mixing at 1053 and 1338 nm was then realized in a LiB 3 O 5 (LBO) crystal to reach the yellow-orange radiation. We obtained a CW output power of 235 mW at 589 nm with a pump laser diode emitting 17.8 W at 808 nm

Radiation induced deep level defects in bipolar junction transistors under various bias conditions

International Nuclear Information System (INIS)

Liu, Chaoming; Yang, Jianqun; Li, Xingji; Ma, Guoliang; Xiao, Liyi; Bollmann, Joachim

2015-01-01

Bipolar junction transistor (BJT) is sensitive to ionization and displacement radiation effects in space. In this paper, 35 MeV Si ions were used as irradiation source to research the radiation damage on NPN and PNP bipolar transistors. The changing of electrical parameters of transistors was in situ measured with increasing irradiation fluence of 35 MeV Si ions. Using deep level transient spectroscopy (DLTS), defects in the bipolar junction transistors under various bias conditions are measured after irradiation. Based on the in situ electrical measurement and DLTS spectra, it is clearly that the bias conditions can affect the concentration of deep level defects, and the radiation damage induced by heavy ions.

Acute cataract in the rat after exposure to radiation in the 300 nm wavelength region

International Nuclear Information System (INIS)

Soederberg, P.G.

1988-01-01

Experimental and epidemiological data indicate a correlation between exposure to UV radiation and cataract morbidity. UV radiation induced cataract is thought to be evoked by photochemical mechanisms. The present investigation resolves the macroscopical events in the rat lens after a one dose exposure to spectrally and radiometrically well defined UV radiation, as revealed in light- and dark-field illumination. The macroscopic sequence of events is related to the morphology as revealed by light- and electron microscopy. The radiation was found to alter the chromation pattern and to induce morphological changes indicating a disturbance of the cellular water balance. The latter is assumed to cause the acute UV radiation induced opacification of the lens. It is suggested that future investigations of the toxic effects of UV radiation in the lens should focus on how UV radiation effects the chromatin and the cellular water balance. (author)

Radiation - induced changes in the optical properties of hemoglobin molecule

International Nuclear Information System (INIS)

Selim, N.S; El-Marakby, S.M.

2009-01-01

Adult male albino rats were exposed to different doses of gamma radiation from Cs-137 source. Hemoglobin samples were analyzed 24 hrs after irradiation. The UV-visible spectrum of hemoglobin molecule was measured in the range 200 to 700 nm. The overall spectrum of the hemoglobin molecule showed hypochromicity that increased with dose increase. To investigate the effect of radiation on the hemoglobin molecule, different parameters of the spectrum were calculated: molar absorption coefficient, absorption cross section, transition dipole moment , dipole length, the optical energy gap and activation energy for each characteristic peak. The obtained results revealed that the radiation effect can induce rearrangement of the transition dipole moments and change molecular energy levels of the hemoglobin molecule

New even parity energy levels of Pr I found by excitation of transitions in the region 560 - 695 nm

Energy Technology Data Exchange (ETDEWEB)

Syed, Tanweer Iqbal; Khan, Shamim; Imran, Siddiqui; Zaheer, Uddin; Windholz, Laurentius [Inst. f. Experimentalphysik, Techn. Univ. Graz, Petersgasse 16, A-8010 Graz (Austria)

2011-07-01

The knowledge of electronic levels is essentially needed for a description of the interactions between the electrons of an atom and for the classification of an atomic spectrum. We have studied the hyperfine structure of Praseodymium spectral lines in the region from 560 to 695 nm. The hyperfine structure of a large number of unclassified Pr I-lines have been investigated by using the method of laser induced fluorescence in a hollow cathode discharge. During this investigation, we have discovered twelve energy levels with even parity, which were previously unknown. The excitation source was a ring dye laser operated with R6G, Kiton red, or DCM. J-quantum numbers and magnetic dipole interaction constants A for upper and lower levels have been determined from the recorded hyperfine structures. The energies of new levels have been determined by using these constants, excitation and fluorescence wavelengths. Promising excitation wavelengths have been taken from Fourier transform spectra. The new levels were confirmed by at least one second laser excitation.

Absorption coefficients for water vapor at 193 nm from 300 to 1073 K

Science.gov (United States)

Kessler, W. J.; Carleton, K. L.; Marinelli, W. J.

1993-01-01

Measurements of the water absorption coefficient at 193 nm from 300 to 1073 K are reported. The measurements were made using broadband VUV radiation and a monochromator-based detection system. The water vapor was generated by a saturator and metered into a flowing, 99 cm absorption cell via a water vapor mass flow meter. The 193 nm absorption coefficient measurements are compared to room temperature and high temperature shock tube measurements with good agreement. The absorption can be parameterized by a nu3 vibrational mode reaction coordinate and the thermal population of the nu3 mode.

Resistance of human erythrocytes containing elevated levels of vitamin E to radiation-induced hemolysis

International Nuclear Information System (INIS)

Brown, M.A.

1983-01-01

Human erythrocytes were isolated from the blood of healthy donors and then incubated in the presence of suspensions of alpha-tocopherol for 30 min at 37 degrees C. Unabsorbed tocopherol was removed by centrifugation using several washes of isotonic phosphate-buffered saline. Washed erythrocytes were resuspended to 0.05%. Hct and exposed to hemolyzing doses of 60 Co gamma radiation, and hemolysis was monitored continuously by light scattering at 700 nm in a recording spectrophotometer. The extent of hemolysis with time was sigmoid and data analysis was carried out on the time taken for 50% hemolysis to occur (t50%). The vitamin E content of erythrocytes was significantly elevated by the incubation procedure and resulted in the cells exhibiting a significantly increased resistance to hemolysis as reflected by the extended t50% values. Oral supplementation of 500 IU of vitamin E per day to eight normal human subjects for a period of 16 days also resulted in their washed erythrocytes exhibiting a significant increase in resistance to radiation-induced hemolysis. When comparing vitamin E incubated cells with control cells, both the dose-reducing factor (DRF) and the time for 50% hemolysis quotient (Qt50%) were observed to increase with increasing radiation dose

Carcinogenesis and low-level ionizing radiation with special reference to lung cancer and exposure to radon daughters

Energy Technology Data Exchange (ETDEWEB)

Fabrikant, J.I.

1982-04-01

Of the important health effects of ionizing radiation, three important late effects - carcinogenesis, teratogenesis and mutagenesis are of greatest concern. This is because any exposure, even at low levels, carries some risk of such deleterious effects. As the dose of radiation increases above very low levels, the risk of health effects increases. Cancer-induction is the most important late somatic effect of low-dose ionizing radiation. Solid cancers, rather than leukemia, are principal late effects in exposed individuals. Tissues vary greatly in their susceptibility to radiation carcinogenesis. The most frequently occurring radiation-induced cancers in man include, in decreasing order of susceptibility: the female breast, the thyroid gland, the blood-forming tissues, the lung, certain organs of the gastrointestinal tract, and the bones. A number of biological and physical factors affect the cancer risk, such as age, sex, life-style, LET, and RBE. Despite uncertainty about low-level radiation risks, regulatory and advisory bodies must set standards for exposure, and individuals need information to be able to make informed judgments for themselves. From the point of view of the policy maker, the overriding concern is the fact that small doses of radiation can cause people to have more cancers than would otherwise be expected. While concern for all radiation effects exists, our human experience is limited to cancer-induction in exposed populations. This discussion is limited to cancer risk estimation and decision-making in relation to the health effects on populations of exposure to low levels of ionizing radiation. Here, low-level radiation will refer to yearly whole-body doses up to 5 rems or 0.05 Sv, or to cumulative doses up to 50 rems or 0.5 Sv from low-LET radiation and from high-LET radiation. (ERB)

Carcinogenesis and low-level ionizing radiation with special reference to lung cancer and exposure to radon daughters

International Nuclear Information System (INIS)

Fabrikant, J.I.

1982-04-01

Of the important health effects of ionizing radiation, three important late effects - carcinogenesis, teratogenesis and mutagenesis are of greatest concern. This is because any exposure, even at low levels, carries some risk of such deleterious effects. As the dose of radiation increases above very low levels, the risk of health effects increases. Cancer-induction is the most important late somatic effect of low-dose ionizing radiation. Solid cancers, rather than leukemia, are principal late effects in exposed individuals. Tissues vary greatly in their susceptibility to radiation carcinogenesis. The most frequently occurring radiation-induced cancers in man include, in decreasing order of susceptibility: the female breast, the thyroid gland, the blood-forming tissues, the lung, certain organs of the gastrointestinal tract, and the bones. A number of biological and physical factors affect the cancer risk, such as age, sex, life-style, LET, and RBE. Despite uncertainty about low-level radiation risks, regulatory and advisory bodies must set standards for exposure, and individuals need information to be able to make informed judgments for themselves. From the point of view of the policy maker, the overriding concern is the fact that small doses of radiation can cause people to have more cancers than would otherwise be expected. While concern for all radiation effects exists, our human experience is limited to cancer-induction in exposed populations. This discussion is limited to cancer risk estimation and decision-making in relation to the health effects on populations of exposure to low levels of ionizing radiation. Here, low-level radiation will refer to yearly whole-body doses up to 5 rems or 0.05 Sv, or to cumulative doses up to 50 rems or 0.5 Sv from low-LET radiation and from high-LET radiation

Investigation of the electromagnetic radiation field level in the vicinity of Damascus international airport

International Nuclear Information System (INIS)

Abukassem, I.

2011-07-01

The aim of this work is to estimate the electromagnetic radiation exposure of Damascus international airport workers.Different kinds of electromagnetic wave sources exist in the vicinity of the airport, for example, mobile phone base stations. It was found that the exposure level in all studied points (offices, halls, traffic control tour, etc) is lower than the international restriction levels. Few recommendations were given for some work situation or places where the measured electromagnetic radiation levels were relatively high.(author)

Absorbance detector for high performance liquid chromatography based on a deep-UV light-emitting diode at 235nm.

Science.gov (United States)

da Silveira Petruci, João Flavio; Liebetanz, Michael G; Cardoso, Arnaldo Alves; Hauser, Peter C

2017-08-25

In this communication, we describe a flow-through optical absorption detector for HPLC using for the first time a deep-UV light-emitting diode with an emission band at 235nm as light source. The detector is also comprised of a UV-sensitive photodiode positioned to enable measurement of radiation through a flow-through cuvette with round aperture of 1mm diameter and optical path length of 10mm, and a second one positioned as reference photodiode; a beam splitter and a power supply. The absorbance was measured and related to the analyte concentration by emulating the Lambert-Beer law with a log-ratio amplifier circuitry. This detector showed noise levels of 0.30mAU, which is comparable with our previous LED-based detectors employing LEDs at 280 and 255nm. The detector was coupled to a HPLC system and successfully evaluated for the determination of the anti-diabetic drugs pioglitazone and glimepiride in an isocratic separation and the benzodiazepines flurazepam, oxazepam and clobazam in a gradient elution. Good linearities (r>0.99), a precision better than 0.85% and limits of detection at sub-ppm levels were achieved. Copyright © 2017 Elsevier B.V. All rights reserved.

A possible methodological approach to setting up control level of radiation factors

International Nuclear Information System (INIS)

Devyatajkin, E.V.; Abramov, Yu.V.

1986-01-01

The mathematical formalization of the concept of control levels (CL) which enables one to obtain CL numerical values of controllable parameters required for rapid control purposes is described. The initial data for the assessment of environmental radioactivity are the controllable parameter values that is practical characteristic of controllable radiation factor showing technically measurable or calculation value. The controllable parameters can be divided into two classes depending on the degree of radiation effect on a man: possessing additivity properties (dosimetric class) and non-possessing (radiation class, which comprises the results of control of medium alteration dynamics, equipment operation safety, completeness of protection measures performance). The CL calculation formulas with account for requirements of radiation safety standards (RSS-76) are presented

Critical review of the Hanford worker studies: cancer risk and low-level radiation

International Nuclear Information System (INIS)

Savitz, D.A.

1983-01-01

Current estimates of cancer risks attributable to low-level radiation exposure are extrapolated from effects observed at higher doses. The inherent uncertainties in this approach make direct study of low-dose effects in human populations of great significance. Employees of the Hanford works in Richland, Washington constitute a large group of workers exposed to low-level radiation. The cancer mortality patterns in relation to radiation dose have been discussed by numerous investigators beginning with Mancuso, Stewart, and Kneale in 1977 and continuing to the present. These studies and their published critiques are summarized, with an effort to account for discrepant results by careful review of the analytic methods. Detailed consideration is given to exposure definition, classification of health outcomes, latency, the statistical methods employed, and selection biases. From this, it is concluded that (a) total cancers are unrelated to radiation exposure among these workers; (b) multiple myeloma and pancreatic cancer show a positive association with radiation dose based upon a few highly exposed cases; and (c) the relationship of radiosensitive cancers in the aggregate to radiation exposure is unresolved. Further study of the temporal course of exposure and latency in a classical cohort analysis of radiosensitive cancers might be informative, with special attention to the possibility of selection for jobs within the cohort

Estudios de series temporales de energía solar UV-B de 305 nm y espesor de la capa de ozono estratosférico en Arica, norte de Chile Study of time series for 305 nm solar energy UV-B and stratospheric ozone layer thickness Arica in the north of Chile

Directory of Open Access Journals (Sweden)

Miguel Rivas

2011-08-01

Full Text Available En este trabajo se muestran los resultados del análisis de las series temporales de la energía solar medida a nivel del suelo, en la banda de 305 nm, y el espesor de la capa de ozono estratosférico. El rasgo más importante es la independencia de los valores de energía a nivel del suelo respecto de la variabilidad de corto periodo de la capa de ozono, siendo probablemente efectos meteorológicos locales los que llevan el mayor peso de la varianza.In this paper, the results obtained by analyzing time series of ground level energy of the solar radiation in the 305 nm band and stratospheric ozone layer thickness are shown. The most relevant feature found is the independence of the variability of the ground level energy with respect to the short period variations of the ozone layer, being the meteorological local effects those which more heavily affect the variability.

Approaches to assign security levels for radioactive substances and radiation sources

International Nuclear Information System (INIS)

Ivanov, M.V.; Petrovskij, N.P.; Pinchuk, G.N.; Telkov, S.N.; Kuzin, V.V.

2011-01-01

The article contains analyzed provisions on categorization of radioactive substances and radiation sources according to the extent of their potential danger. Above provisions are used in the IAEA documents and in Russian regulatory documents for differentiation of regulatory requirements to physical security. It is demonstrated that with the account of possible threats of violators, rules of physical protection of radiation sources and radioactive substances should be amended as regards the approaches to assign their categories and security levels [ru

Effects of low-level radiation on biologic systems: a literature review

International Nuclear Information System (INIS)

Best, T.L.; Hoditschek, B.

1980-12-01

This review presents an organized survey of scientific literature dealing with the biologic effects of low-level radiation. It includes brief discussions of topics of particular interest, a listing of useful review articles, an extensive bibliography, and listings of sources that can be used to update this document in the future. The topics discussed include experimental studies, the linear hypothesis, medical effects, occupational effects, effects of exposure to naturally occurring radiation, consumer products, and laws and regulations

Investigation of environmental natural penetrating radiation level in Anhui province

International Nuclear Information System (INIS)

Zhu Jingqiu; Chen Shuping; Jiang Shan; Zhu Xingsheng; Huang Jiangbin; Wu Chuanyong; Wang Weining

1992-01-01

The methods and results of the investigation on natural penetrating radiation level in Anhui Province in 1987 are presented. The results show that: (1) The point-weighted, area-weighted and population-weighted average value of natural γ radiation dose rate for field is 5.67, 5.62 and 5.55 x 10 -8 Gy· -1 , respectively; (2) The point-weighted average value of natural γ radiation dose rate for road is 5.38 x 10 -8 Gy·h -1 ; (3) The point-weighted and population-weighted average value of natural γ radiation dose rate inside buildings is 9.59 and 9.36 x 10 -8 Gy·h -1 , respectively; (4) The point-weighted and population-weighted average value of the dose rate inside buildings from cosmic ray is 2.64 and 2.62 x 10 -8 ·h -1 , and outside buildings is 2.95 and 2.94 x 10 -8 ·h -1 , respectively; (5) The point-weighted and population-weighted average value of natural penetrating radiation dose rate inside buildings is 12.23 and 11.99 x 10 -8 Gy·h -1 , outside buildings is 8.62 and 8.49 x 10 -8 ·h -1 , respectively; (6) The annual effective dose equivalent from natural γ radiation, cosmic ray and natural penetrating radiation is 0.51, 0.24, and 0.75 mSv, respectively; and correspondingly, the annual collective effective dose equivalent is 2.5, 1.2 and 3.7 x 10 4 man·Sv, respectively

Photo-removal of sulfamethoxazole (SMX) by photolytic and photocatalytic processes in a batch reactor under UV-C radiation (λmax = 254 nm)

International Nuclear Information System (INIS)

Nasuhoglu, Deniz; Yargeau, Viviane; Berk, Dimitrios

2011-01-01

In this study, photolytic and photocatalytic removal of the antibiotic sulfamethoxazole (SMX) under UVC radiation (λ = 254 nm) was investigated. The light intensity distribution inside the batch photoreactor was characterized by azoxybenzene actinometry. The intensity of incident radiation was found to be a strong function of position inside the reactor. 12 mg L -1 of SMX was completely removed within 10 min of irradiation under UVC photolysis, compared to 30 min under TiO 2 photocatalysis. COD measurement was used as an indication of the mineralization efficiency of both processes and higher COD removal with photocatalysis was shown. After 6 h of reaction with photolysis and photocatalysis, 24% and 87% removal of COD was observed, respectively. Two of the intermediate photo-products were identified as sulfanilic acid and 3-amino-5-methylisoxazole by direct comparison of the HPLC chromatograms of standards to those of treated solutions. Ecotoxicity of treated and untreated solutions of SMX towards Daphnia magna was also investigated. It was found that a 3:1 ratio of sample to standard freshwater and a high initial concentration of 60 mg L -1 of SMX were used to obtain reliable and reproducible results. The photo-products formed during photocatalytic and photolytic processes were shown to be generally more toxic than the parent compound.

Effects of ionizing radiation on the physicochemical properties of red wine Cabernet Sauvignon

International Nuclear Information System (INIS)

Silva, Fellipe S.; Santos, Anderson R.L.; Pereira, Walsan W.

2015-01-01

Oenology has as its main purpose the continuous improvement of wine quality without jeopardizing its proprieties, and the intent is to make these improvements using innovative new technologies. The objective of the present work is to assess the effect of ionizing radiation on the physicochemical properties of Cabernet Sauvignon that may lead to changes in wine quality, aging process and other related characteristics. The samples used for this process were irradiated using an Argonaut reactor powered at 340 Watts and with a thermal neutron fluency of 10 9 n.cm -2 .s -1 . For irradiation experiments, the samples were put into the reactor chamber until the reactor reached criticality and for an additional 30 minutes while receiving radiation. The analyzed data included density, alcoholic, ashes and spectrophotometric measurements of absorbance at wavelengths of 420, 520 and 620 nm. Increased absorbance values at 420 nm indicate an increase in tannin composition of the wine and therefore a higher level of oxidation. Intriguingly, a rise in absorbance was also observed at 520 nm for the same test samples; which is inconsistent with published data on irradiated cachaca that showed that anthocyanin levels dropped at 520 nm after irradiation. In summary, for measurements made at a fluency of 109 n/cm 2 .s for 30 min, the effects were minimal, which requires a higher dose to have better effects. Future studies should evaluating dosing effects of irradiation on improving the quality of the Cabernet Sauvignon. (author)

Effects of ionizing radiation on the physicochemical properties of red wine Cabernet Sauvignon

Energy Technology Data Exchange (ETDEWEB)

Silva, Fellipe S.; Santos, Anderson R.L.; Pereira, Walsan W., E-mail: fellipess@ird.gov.br, E-mail: aleiras@ird.gov.br, E-mail: walsan@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

2015-07-01

Oenology has as its main purpose the continuous improvement of wine quality without jeopardizing its proprieties, and the intent is to make these improvements using innovative new technologies. The objective of the present work is to assess the effect of ionizing radiation on the physicochemical properties of Cabernet Sauvignon that may lead to changes in wine quality, aging process and other related characteristics. The samples used for this process were irradiated using an Argonaut reactor powered at 340 Watts and with a thermal neutron fluency of 10{sup 9} n.cm{sup -2}.s{sup -1}. For irradiation experiments, the samples were put into the reactor chamber until the reactor reached criticality and for an additional 30 minutes while receiving radiation. The analyzed data included density, alcoholic, ashes and spectrophotometric measurements of absorbance at wavelengths of 420, 520 and 620 nm. Increased absorbance values at 420 nm indicate an increase in tannin composition of the wine and therefore a higher level of oxidation. Intriguingly, a rise in absorbance was also observed at 520 nm for the same test samples; which is inconsistent with published data on irradiated cachaca that showed that anthocyanin levels dropped at 520 nm after irradiation. In summary, for measurements made at a fluency of 109 n/cm{sup 2}.s for 30 min, the effects were minimal, which requires a higher dose to have better effects. Future studies should evaluating dosing effects of irradiation on improving the quality of the Cabernet Sauvignon. (author)

Biological effects of low-level laser irradiation on umbilical cord mesenchymal stem cells

International Nuclear Information System (INIS)

Chen, Hongli; Wang, Hong; Li, Yingxin; Liu, Weichao; Chen, Zhuying; Wang, Chao

2016-01-01

Low-level laser irradiation (LLLI) can enhance stem cell (SC) activity by increasing migration and proliferation. This study investigated the effects of LLLI on proliferation, enzymatic activity, and growth factor production in human umbilical cord mesenchymal SCs (hUC-MSCs) as well as the underlying mechanisms. hUC-MSCs were assigned to a control group (non-irradiation group) and three LLLI treatment groups (635 nm group, 808 nm group, and 635/808 nm group). Laser power density and energy density of 20 mW/cm"2 and 12 J/cm"2, respectively, were used for each experiment. The proliferation rate was higher in the 635 nm as compared to the other groups. LLLI at 808 nm did not induce cell proliferation. ROS levels in cells exposed to 635, 808, and 635/808 nm radiation were increased by 52.81%, 26.89%, and 21.15%, respectively, relative to the control group. CAT, tGPx, and SOD activity was increased. LLLI at 808 nm increased the levels of IL-1, IL-6, and NFκB but not VEGF. LLLI improved hUC-MSCs function and increased antioxidant activity. Dual-wavelength LLLI had more potent effects on hUC-MSCs than single-wavelength treatment. LLLI has potential applications in the preconditioning of hUC-MSCs in vitro prior to transplantation, which could improve the regenerative capacity of cells.

Biological effects of low-level laser irradiation on umbilical cord mesenchymal stem cells

Science.gov (United States)

Chen, Hongli; Wang, Hong; Li, Yingxin; Liu, Weichao; Wang, Chao; Chen, Zhuying

2016-04-01

Low-level laser irradiation (LLLI) can enhance stem cell (SC) activity by increasing migration and proliferation. This study investigated the effects of LLLI on proliferation, enzymatic activity, and growth factor production in human umbilical cord mesenchymal SCs (hUC-MSCs) as well as the underlying mechanisms. hUC-MSCs were assigned to a control group (non-irradiation group) and three LLLI treatment groups (635 nm group, 808 nm group, and 635/808 nm group). Laser power density and energy density of 20 mW/cm2 and 12 J/cm2, respectively, were used for each experiment. The proliferation rate was higher in the 635 nm as compared to the other groups. LLLI at 808 nm did not induce cell proliferation. ROS levels in cells exposed to 635, 808, and 635/808 nm radiation were increased by 52.81%, 26.89%, and 21.15%, respectively, relative to the control group. CAT, tGPx, and SOD activity was increased. LLLI at 808 nm increased the levels of IL-1, IL-6, and NFκB but not VEGF. LLLI improved hUC-MSCs function and increased antioxidant activity. Dual-wavelength LLLI had more potent effects on hUC-MSCs than single-wavelength treatment. LLLI has potential applications in the preconditioning of hUC-MSCs in vitro prior to transplantation, which could improve the regenerative capacity of cells.

Biological effects of low-level laser irradiation on umbilical cord mesenchymal stem cells

Energy Technology Data Exchange (ETDEWEB)

Chen, Hongli; Wang, Hong; Li, Yingxin, E-mail: yingxinli2005@126.com; Liu, Weichao; Chen, Zhuying [Key Laboratory of Laser Medicine of Tianjin, Institute of Biomedical Engineering, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300192 (China); Wang, Chao [Biomedical Engineering and Technology College, Tianjin Medical University, Tianjin, 300070 (China)

2016-04-15

Low-level laser irradiation (LLLI) can enhance stem cell (SC) activity by increasing migration and proliferation. This study investigated the effects of LLLI on proliferation, enzymatic activity, and growth factor production in human umbilical cord mesenchymal SCs (hUC-MSCs) as well as the underlying mechanisms. hUC-MSCs were assigned to a control group (non-irradiation group) and three LLLI treatment groups (635 nm group, 808 nm group, and 635/808 nm group). Laser power density and energy density of 20 mW/cm{sup 2} and 12 J/cm{sup 2}, respectively, were used for each experiment. The proliferation rate was higher in the 635 nm as compared to the other groups. LLLI at 808 nm did not induce cell proliferation. ROS levels in cells exposed to 635, 808, and 635/808 nm radiation were increased by 52.81%, 26.89%, and 21.15%, respectively, relative to the control group. CAT, tGPx, and SOD activity was increased. LLLI at 808 nm increased the levels of IL-1, IL-6, and NFκB but not VEGF. LLLI improved hUC-MSCs function and increased antioxidant activity. Dual-wavelength LLLI had more potent effects on hUC-MSCs than single-wavelength treatment. LLLI has potential applications in the preconditioning of hUC-MSCs in vitro prior to transplantation, which could improve the regenerative capacity of cells.

Novel photoinducible protective system in the Candida Guilliermondii under mid-ultraviolet radiation effect

International Nuclear Information System (INIS)

Frajkin, G.Ya.; Pinyaskina, E.V.; Strakhovskaya, M.G.

1995-01-01

Resistance of the Candida guilliermondii cells to ultraviolet radiation (290-320 nm, 400-750 nm) is studied. Presence of previously unknown photoinducible protective mechanism in yeasts, providing for increase in cell stability to mid-ultraviolet radiation, biologically most active in the solar radiation spectrum, is revealed. 9 refs.; 3 figs

Techniques for detecting and determining risks from low-level radiation

International Nuclear Information System (INIS)

Boice, J.D.

1980-01-01

Epidemiology is the study of disease in man. In evaluating radiation hazards, analytic studies have utilized the cohort type of investigation (where persons exposed and not exposed to radiation are followed forward in time for determination of disease experience) or case-control approaches (where persons with and without a specific disease are evaluated for previous exposure to radiation). Most radiation studies have evaluated cohorts (e.g., radiologists), although important case-control studies have been conducted (e.g., childhood leukemia as related to prenatal x ray). At its best, epidemiology is capable fo evaluating relative risks (RR) on the order of 1.4 (i.e., a 40% relative excess). However, the RRs of interest following low doses of radiation (1 rad) are on the order of 1.02-1.002. Thus, not much should be anticipated from direct observations at 1 rad, and indirect approaches must be taken to estimate low-dose effects. Such indirect approaches include evaluating 1) populations exposed to a range of doses, both low and high, where interpolation models can be reasonably applied to estimate low-dose effects; and 2) populations exposed to fractionated doses over a long period of time where the resulting dose-effect relationship theoretically should be linear and the estimation of low-level health effects facilitated

EVALUATION OF THE PROGNOSTIC VALUE OF nm23 GENE EXPRESSION IN BREAST CANCER

Institute of Scientific and Technical Information of China (English)

刘红; 毛慧生; 傅西林; 方志沂; 冯玉梅; 范宇; 李树玲

2002-01-01

Objective: To investigate the expression of nm23 gene and evaluate its prognostic value in breast cancer. Methods: nm23 expressions were detected in 101 breast cancer patients (group 1) by immunohistochemistry. RT-PCR and immunohistochemistry were used to measure expressions of nm23 gene in another 68 patients with breast cancer (group 2). Results: nm23 gene expression in group 1 was inversely associated with distant metastasis and lymph node metastasis (P<0.05). In 44 patients with negative lymph node, 9 cases progressed to distant metastasis, 7 of them (77.8%) showed low expression of nm23 gene (P<0.05). In 57 patients with positive lymph node, 24 our of 29 patients who had no distant metastasis (82.8%) expressed nm23 gene at high level (P<0.05). Meanwhile, there were 6 patients with distant metastasis in the group 2, all of thenm expressed nm23 gene mRNA at low level. Conclusion: The results showed that nm23 gene might play an independent role in predicting prognosis of breast cancer.

The correlation between osteopontin level and radiation response of malignant gliomas at Cipto Mangunkusumo Hospital

Directory of Open Access Journals (Sweden)

Isnaniah Hasan

2016-12-01

Full Text Available Osteopontin is an endogenous molecular marker for tumor hypoxia, and hypoxia is one of the factors that determine the aggressiveness of the disease. The purpose of this study is to determine the correlation between osteopontin levels and radiation response in malignant glioma. A retrospective cohort study was conducted on 15 malignant glioma patients who underwent radiation therapy from July 2004 to May 2015 at the RSUPN Dr. Cipto Mangunkusumo Hospital. Osteopontin levels were measured from paraffin-embedded tissue using a commercial ELISA kit. Tumor volume was calculated using computed tomography (CT scan and magnetic resonance imaging (MRI images, based on three-dimensional volume measurements. Tumor response was evaluated by comparing pre- and post-radiation tumor volumes using CT scan and MRI images. The mean osteopontin level was 0.49 ± 0.45 ng/mL and the mean percentage change in tumor volume was 8.59 ± 54.22%, with a 60% enlargement in tumor volume. A progressive disease was found in 26.7% of patients. There was a weak but insignificant negative correlation (r = -0.39, p = 0.146 between the level of osteopontin and radiation response. In contrast, there was a strong but insignificant positive correlation (r = +0.68, p = 0.219 between the level of osteopontin and radiation response in the patient group that used the chemosensitizer temozolamide.

Ocular exposure to ultraviolet and visible radiation from light sources

International Nuclear Information System (INIS)

Hietanen, M.

1992-01-01

Exposure of the eyes to UV radiation and blue light of artificial light sources and the sun was evaluated. A spectroradiometer was used to determine the spectral irradiance at 1 nm intervals from 250 to 800 nm. Various groups of workers are at risk of ocular over-exposure to optical radiation, outdoor workers maintenance personnel of bright light source as and wear eye-protectors with effective filtering of UV radiation and blue light. (author)

Radiation-induced taste aversion: effects of radiation exposure level and the exposure-taste interval

International Nuclear Information System (INIS)

Spector, A.C.; Smith, J.C.; Hollander, G.R.

1986-01-01

Radiation-induced taste aversion has been suggested to possibly play a role in the dietary difficulties observed in some radiotherapy patients. In rats, these aversions can still be formed even when the radiation exposure precedes the taste experience by several hours. This study was conducted to examine whether increasing the radiation exposure level could extend the range of the exposure-taste interval that would still support the formation of a taste aversion. Separate groups of rats received either a 100 or 300 R gamma-ray exposure followed 1, 3, 6, or 24 h later by a 10-min saccharin (0.1% w/v) presentation. A control group received a sham exposure followed 1 h later by a 10-min saccharin presentation. Twenty-four hours following the saccharin presentation all rats received a series of twelve 23-h two-bottle preference tests between saccharin and water. The results indicated that the duration of the exposure-taste interval plays an increasingly more important role in determining the initial extent of the aversion as the dose decreases. The course of recovery from taste aversion seems more affected by dose than by the temporal parameters of the conditioning trial

The generation of a continuous-wave Nd:YVO4/LBO laser at 543 nm by direct in-band diode pumping at 888 nm

International Nuclear Information System (INIS)

Fu, S C; Wang, X; Chu, H

2013-01-01

We report the generation of a green laser at 543 nm by intracavity frequency doubling of the continuous-wave (cw) laser operation of a 1086 nm Nd:YVO 4 laser under 888 nm diode pumping into the emitting level 4 F 3/2 . An LiB 3 O 5 (LBO) crystal, cut for critical type I phase matching at room temperature, is used for the laser second-harmonic generation. At an incident pump power of 17.8 W, as high as 4.53 W cw output power at 543 nm is achieved. The optical-to-optical conversion efficiency is up to 25.4%, and the fluctuation of the green output power is better than 2.3% in a 30 min period. (paper)

Estimation of the aerosol radiative forcing at ground level, over land, and in cloudless atmosphere, from METEOSAT-7 observation: method and case study

Directory of Open Access Journals (Sweden)

T. Elias

2008-02-01

Full Text Available A new method is proposed to estimate the spatial and temporal variability of the solar radiative flux reaching the surface over land (DSSF, as well as the Aerosol Radiative Forcing (ARF, in cloud-free atmosphere. The objective of regional applications of the method is attainable by using the visible broadband of METEOSAT-7 satellite instrument which scans Europe and Africa on a half-hourly basis. The method relies on a selection of best correspondence between METEOSAT-7 radiance and radiative transfer computations.

The validation of DSSF is performed comparing retrievals with ground-based measurements acquired in two contrasted environments: an urban site near Paris and a continental background site located South East of France. The study is concentrated on aerosol episodes occurring around the 2003 summer heat wave, providing 42 cases of comparison for variable solar zenith angle (from 59° to 69°, variable aerosol type (biomass burning emissions and urban pollution, and variable aerosol optical thickness (a factor 6 in magnitude. The method reproduces measurements of DSSF within an accuracy assessment of 20 W m⁻² (5% in relative in 70% of the situations, and within 40 W m⁻² in 90% of the situations, for the two case studies considered here.

Considering aerosol is the main contributor in changing the measured radiance at the top of the atmosphere, DSSF temporal variability is assumed to be caused only by aerosols, and consequently ARF at ground level and over land is also retrieved: ARF is computed as the difference between DSSF and a parameterised aerosol-free reference level. Retrievals are linearly correlated with the ground-based measurements of the aerosol optical thickness (AOT: sensitivity is included between 120 and 160 W m⁻² per unity of AOT at 440 nm. AOT being an instantaneous measure indicative of the aerosol columnar amount, we prove the feasibility to infer instantaneous

Physical, biochemical and physiological effects of ultraviolet radiation on Brassica napus and Phaseolus vulgaris

International Nuclear Information System (INIS)

Cen Yan-Ping.

1993-01-01

In order to follow some of the changes induced by ultraviolet-B (UV-B, 280-320 nm) radiation in Phaseolus vulgaris and Brassica napus, experiments were designed to localize sites of changes in leaves and to correlate some of the physiological and biochemical changes with penetration of UV-B radiation. B.napus was exposed to 8.9 kJ m -2 day -1 biologically effective UV-B radiation (UV-B BE ). The penetration of UV-B radiation into the leaf was followed using a quartz fibre optic microprobe. Monochromatic radiation at 310 nm was decreased by ca 50 and 34% in the adaxial and abaxial epidermis, respectively, in plants not exposed to UV-B, whereas the radiation was decreased by ca 70 and 42%, respectively, in the same region in UV-treated plants. Polychromatic radiation showed a wavelength dependent change mainly for the collimated radiation. The results correlated with the distribution of phenolic compounds analysed from 40 μm paradermal leaf sections. The first adaxial section (40μm) contained 35% of the whole leaf sample flavonoid glycosides in control plants, and 66% in UV-treated plants. Hydroxycinnamic acid derivatives increased by 26% in UV-treated plants relative to controls. The ratio of quercetin to kaempferol derivatives increased from 0.11 in controls to 0.91 in leaves of UV-treated plants. The leaf epidermis protected the inner leaf tissue where most of the photosynthetic apparatus is located. P. vulgaris was subjected to 6.17 kJ m -2 day -1 UV-B BE with different levels of visible light. The largest UV-induced changes in photosynthesis, chlorophyll, carotenoids, UV-screening pigments, and surface leaf reflectance occurred under growth conditions of low levels of visible light together with UV radiation

Physical, biochemical and physiological effects of ultraviolet radiation on Brassica napus and Phaseolus vulgaris

Energy Technology Data Exchange (ETDEWEB)

Cen Yan-Ping

1993-12-31

In order to follow some of the changes induced by ultraviolet-B (UV-B, 280-320 nm) radiation in Phaseolus vulgaris and Brassica napus, experiments were designed to localize sites of changes in leaves and to correlate some of the physiological and biochemical changes with penetration of UV-B radiation. B.napus was exposed to 8.9 kJ m{sup -2} day{sup -1} biologically effective UV-B radiation (UV-B{sub BE}). The penetration of UV-B radiation into the leaf was followed using a quartz fibre optic microprobe. Monochromatic radiation at 310 nm was decreased by ca 50 and 34% in the adaxial and abaxial epidermis, respectively, in plants not exposed to UV-B, whereas the radiation was decreased by ca 70 and 42%, respectively, in the same region in UV-treated plants. Polychromatic radiation showed a wavelength dependent change mainly for the collimated radiation. The results correlated with the distribution of phenolic compounds analysed from 40 {mu}m paradermal leaf sections. The first adaxial section (40{mu}m) contained 35% of the whole leaf sample flavonoid glycosides in control plants, and 66% in UV-treated plants. Hydroxycinnamic acid derivatives increased by 26% in UV-treated plants relative to controls. The ratio of quercetin to kaempferol derivatives increased from 0.11 in controls to 0.91 in leaves of UV-treated plants. The leaf epidermis protected the inner leaf tissue where most of the photosynthetic apparatus is located. P. vulgaris was subjected to 6.17 kJ m{sup -2} day{sup -1} UV-B{sub BE} with different levels of visible light. The largest UV-induced changes in photosynthesis, chlorophyll, carotenoids, UV-screening pigments, and surface leaf reflectance occurred under growth conditions of low levels of visible light together with UV radiation.

Risk evaluation - conventional and low level effects of radiation

International Nuclear Information System (INIS)

Bond, V.P.; Varma, M.N.

1984-04-01

Any discussion of the risk of exposure to potentially-hazardous agents in the environment inevitably involves the question of whether the dose effect curve is of the threshold or linear, non-threshold type. A principal objective of this presentation is to show that the function is actually two separate relationships, each representing distinctly different functions with differing variables on the axes, and each characteristic of quite different functions with differing variables on the axes, and each characteristic of quite different disciplines (i.e., the threshold function, of Pharmacology, Toxicology and Medicine [PTM]; the linear, non-threshold function, of Public Health including safety and accident statistics [PHS]). It is shown that low-level exposure (LLE) to radiation falls clearly in the PHS category. A function for cell dose vs. the fraction of single cell quantal responses is characterized, which reflects the absolute and relative sensitivities of cells. Acceptance of this function would obviate any requirement for the use in Radiation Protection of the concepts of a standard radiation, Q, dose equivalent and rem. 9 references, 4 figures

More on direct estimates of low-level radiation risks

International Nuclear Information System (INIS)

Rinsky, R.

1982-01-01

In an epidemiologic study of mortality at the Portsmouth Naval Shipyard (PNS), the National Institute for Occupational Safety and Health (NIOSH) found no evidence of excess deaths due to leukemia or other cancers among workers exposed to low levels of ionizing radiation. In a subsequent analysis, Bross and Driscoll identified excess lung cancer mortality in PNS workers with lifetime radiation dose of 1 rem or greater and with more than 15 years' latency since first radiation exposure. Although that observation may be important and is currently being examined through case-control analyses, it must be recognized that Bross and Driscoll extracted their observation from matrices of over 4,000 data cells apparently by recombination of innumerable possible permutations of dosage and latency intervals. For that reason, their finding can be regarded as no more than a suggestion for further study. It certainly does not represent a proper scientific conclusion. Bross and Driscoll's analysis illustrates the hazard of performing multiple statistical comparisons on complex data sets in the absence of a priori hypotheses