Application of sourceless efficiency calibration in activity measurement of gas source in Marinelli beaker / 中国辐射卫生

Objective To optimize the Marinelli beaker with the simulation of Laboratory Sourceless Object Calibration Software (LabSOCS), to investigate the detection efficiency of HPGe detector in measuring noble gas, and to provide a reference for the measurement and optimization of noble gas effluent from nuclear power plants. Methods LabSOCS was used to establish a Marinelli beaker model to investigate the relationship of gamma ray detection efficiency of noble gas with gas components, gas density, size and volume of the Marinelli beaker, and the shape of source container. Results The gas components had little effect on the detection efficiency of the noble gas in the Marinelli beaker. The gas density had a relatively great effect on the detection efficiency of low-energy gamma ray. The Marinelli beaker of appropriate height and radius enabled the HPGe detector to get better measurement results. For the BE5030 HPGe detector, the highest detection efficiency of the Marinelli beakers of different volumes were observed at the location where the radius/height ratio was 0.7, and the optimal values of height and radius were given for the Marinelli beakers of different volumes. Conclusion Choosing Marinelli beaker of the appropriate size can improve the detection efficiency of noble gas in the effluent from nuclear power plants.

Effects of sieved particle size and equilibration time on the measurement of radionuclides in soil by gamma-ray spectrometer / 中国辐射卫生

Objective The effect of sieved particle size and equilibration time of soil samples on the measurement of radionuclides was studied to improve the accuracy of the specific activity of radionuclides in soil samples measured by gamma spectrometer. Methods The collected soil samples were dried and divided into four parts. After sieved with width of the mesh 2.0 mm, 1.0 mm, 0.5 mm and 0.25 mm respectively, they were filled into sample containers and sealed. The activity concentrations of 226Ra, 210Pb, 228Ra, 40K and 137Cs in different sieved soil samples were then measured at the sealed interval of 0, 4, 8, 12, 16, 21, 25 and 29 days by HPGe gamma-ray spectrometry respectively. Results The coefficients of variation ofthe specific activities of 226Ra, 210Pb, and 228Ra in soil samples measured at different equilibration intervals range from 0.9% to 4.3%. The coefficients of variation of the specific activities of 226Ra, 210Pb, 228Ra, 40K and 137Cs in soil samples with different sieved particle sizes range from 3.7% to 14.1%. Conclusion When the specific activities of radionuclides are determined by gamma-ray spectrometer, the effect of the sieved particle size on the measurement result must be considered, and its impact is higher than the equilibration time. This study is very useful for improving the accuracy of the determination of radionuclides in soil sample using gamma-ray spectrometer.

Clinical analysis of gamma-ray fractionated stereotactic radiotherapy for intracranial metastatic polycystic tumors / 中华放射肿瘤学杂志

Objective To analyze the clinical efficacy of gamma-ray fractionated stereotactic radiotherapy (FSRT) in the treatment of intracranial metastatic polycystic tumors.Methods Forty cases with 61 metastatic polycystic tumors were selected from 189 patients with 373 intracranial metastatic tumors admitted to our hospital from 2013 to 2015.All cases received gamma-ray FSRT.The isodose line at 50％ was defined as the prescription dose.The prescription dose was ranged from 40 to 48 Gy/10-12f.The survival rate was calculated by Kaplan-Meier method.The single factor analysis was performed by Log-rank method.Results The median follow-up time was 21months (range:6-39 months).The median survival time was 15.3 months.The 6-month,1-and 2-year local control rate was 93％,82％ and 79％,respectively.The 1-and 2-year survival rate was 63％ and 30％.Single factor analysis demonstrated that the volume of cysts and the volume of lesions were not significantly correlated with local control rate (P=0.17 and 0.48).Conclusion Gamma-ray FSRT can be adopted to treat intracranial metastatic polycystic tumors,which yields similar clinical efficacy to metastatic solid tumors.It deserves wide application in clinical practice due to high local control rate and safety.

Analysis of background variations in low-background γ-ray spectrometer with lead shielding / 中华放射医学与防护杂志

Objective To study the variation in net count rates of natural radionuclides in background of gamma-ray spectrometer,so as to provide a scientific basis for reducing the effect of background fluctuations on sample measurement.Methods The unscheduled background spectrum obtained using two high-purity gamma-ray spectrometers during 2013-2017 were collected,and then the net count rates of 210pb,234Th,212Pb,214pb,208Tl,214Bi,228Ac and 40K were calculated and analyzed by aid of statistical method.Results There was a significant difference in the net count rates of 210Pb,234Th,212Pb,214Pb,208Tl,214Bi,228Ac and 40K in the background spectrum of gamma-ray spectrometer,and the net count rates of 214Pb,214Bi and 40K was significantly higher than those of 210Pb,234Th,212pb,208Tl and 228Ac.There were no significant differences in the net count rates of these eight natural radionuclides from 2013 to 2017,respectively (P ＞ O.05).However,the coefficients of variation in the net count rates for 214pb and 214Bi were both greater than 50％.Conclusions When the activity concentration of natural radionuclides is determined in a sample by gamma-ray spectrometer,it is critical to subtract the background spectrum obtained recently to ensure the accuracy of the measurement,especially for the low activity concentration of natural radionuclide to be measured.

Comparative study between laser and conventional techniques for class V cavity preparation in gamma-irradiated teeth (in vitro study)

Abstract Objective: The purpose of this study was to compare laser with conventional techniques in class V cavity preparation in gamma-irradiated teeth. Methods: Forty extracted human teeth with no carious lesions were used for this study and were divided into two main groups: Group I (n = 20) was not subjected to gamma radiation (control) and Group II (n=20) was subjected to gamma radiation of 60 Gray. Standard class V preparation was performed in buccal and lingual sides of each tooth in both groups. Buccal surfaces were prepared by the Er,Cr:YSGG laser (Waterlase iPlus) 2780 nm, using the gold handpiece with MZ10 Tip in non-contact and the "H" mode, following parameters of cavity preparation - power 6 W, frequency 50 Hz, 90% water and 70% air, then shifting to surface treatment laser parameters - power 4.5 W, frequency 50 Hz, 80% water and 50% air. Lingual surfaces were prepared by the conventional high-speed turbine using round diamond bur. Teeth were then sectioned mesio-distally, resulting in 80 specimens: 40 of which were buccal laser-treated (20 control and 20 gamma-irradiated specimens) and 40 were lingual conventional high-speed bur specimens (20 control and 20 gamma-irradiated specimens). Results: Microleakage analysis revealed higher scores in both gamma groups compared with control groups. Chi-square test revealed no significant difference between both control groups and gamma groups (p=1, 0.819, respectively). A significant difference was revealed between all 4 groups (p=0.00018). Conclusion: Both laser and conventional high-speed turbine bur show good bond strength in control (non-gamma) group, while microleakage is evident in gamma group, indicating that gamma radiation had a dramatic negative effect on the bond strength in both laser and bur-treated teeth.

Food Processing by Irradiation—–An effective technology for food safety and security.

Radiation processing of food involves controlled application of energy from ionizing radiations from radioisotopes (Cobalt-60 and Caesium-137), electron beam (≤10 MeV) or X-rays (≤5 MeV) in an irradiation chamber shielded by 1.5 - 1.8 m thick concrete walls. Food, either pre-packed or in-bulk, placed in suitable containers is sent into the chamber through an automatic conveyor. Major benefits achieved by radiation processing of food are inhibition of sprouting of tubers and bulbs, delay in ripening and senescence of fruits and vegetables, disinfestations of insect pests in agricultural commodities, destruction of microbes responsible for food spoilage, and elimination of food pathogens and parasites of public health importance. Irradiation produces very little chemical changes in food, and the changes are similar to those by other preservation methods like heat. The radiolytic products and free radicals produced are identical to those present in foods subjected to treatments such as cooking and canning. None of the changes known to occur have been found to be harmful. Radiation processing of food has been approved by various international statutory bodies and organizations to ensure ‘Food Security & Safety’, and overcome ‘Technical barrier to International Trade’ and currently is being practiced in more than 60 countries worldwide.

40K, 226Ra AND 228Ra SERIES IN BOVINE AND POULTRY FEED AND IN DICALCIUM PHOSPHATE (DCP) SAMPLES BY GAMMA-RAY SPECTROMETRY

The aim of this study is to determine the amounts of radionuclides' activity present in samples of feed for young and adult chicken and feed for dairy and beef cattle, as well as in dicalcium phosphate (DCP) (CaHPO4), used as a nutritional supplement for animal feed. Radioactivity in these samples is due to the presence of the 238U and 232Th radioactive series, as well as their daughter. In addition, as it is for environmental samples, the activity of 40K should be an important source of radioactivity in all analyzed samples. Gamma rays were measured using a standard spectroscopy system, with a high-resolution HPGe detector. Measured activities in feed samples ranged from 0.23 to 1.51 Bq.kg-1, 0.67 to 4.21 Bq.kg-1, 0.29 to 1.63 Bq.kg-1 and 236 to 402 Bq.kg-1 for 226Ra, 228 Ra, 228 Th and 40K, respectively. Measured activities in DCP samples were 46.6 Bq.kg-1, 83 Bq.kg-1, 4.20 Bq.kg-1 and 16.61 Bq.kg-1 for 40 K, 226 Ra, 228 Ra and 228 Th, respectively. Although 40K activity has reached hundreds of Becquerel in feed samples, it should not represent a risk to human health, not even to animals, since potassium is an essential mineral to living organisms.

Protective effect of phloroglucinol against gamma radiation-induced oxidative stress in hair follicles

When exposed to gamma-rays, hair follicular cells immediately go through apoptosis, which hampers their rapid differentiation essential for the regeneration of hair. Phloroglucinol (PG) is a phenolic compound of Ecklonia cava, brown algae abundant in Jeju island, Korea. Containing plentiful polyphenols, PG is known for its instructive effects by inhibiting apoptosis, scavenging oxygen radicals, and protecting cells against oxidative stress. In this study, we demonstrate that PG rescues radiosensitive hair follicular cells from gamma radiation-induced apoptosis and DNA damage. To identify protective capacity of PG on hair follicles, we irradiated with 8.5 Gy (1.5 Gy/min) of gamma-rays to the whole body of C57BL/6 mice at day 6 after depilation with or without PG. In mice exposed to radiation, the expression of proapoptotic molecule p53 was downregulated in the skin of PG treated group. On immunohistochemical observation of the skin, PG inhibited the immunoreactivity of p53 and cleaved caspase-3. PG treatment protected hair follicular cells from cell death due to gamma-radiation. Our results suggest that PG presents radioprotective effects by inhibiting apoptosis of radiosensitive hair follicular cells and can protect hair follicular cells from gamma-ray induced damage.

Radiossensibilidade de sementes e segmentos caulinares de maracujazeiro-amarelo submetidos à radiação gama / The radio-sensitivity of gamma-irradiated passion fruit seeds and stem nodal segments

Os objetivos neste estudo foram avaliar os efeitos da radiação γ sobre a sobrevivência e desenvolvimento de gemas de segmentos caulinares e germinação de sementes de maracujazeiro-amarelo (Passiflora edulis f. flavicarpa) in vitro. Os explantes de segmentos caulinares (2cm) contendo uma gema axilar, obtidos a partir de plântulas provenientes da germinação in vitro de sementes de maracujá, foram tratados com raios γ em dosagens variando de 10 a 60Gy e subsequentemente transferidos para meio Murashige e Skoog (MS), suplementado com 4,0mg L-1BAP. Para a irradiação das sementes, foram testadas doses que variaram de 75-200Gy e a germinação e sobrevivência das plântulas foram avaliadas após 30 e 60 dias da inoculação em meio MS, respectivamente. Após 30 dias da irradiação de segmentos caulinares, observou-se redução de 50% na sobrevivência dos explantes e no número de brotações formadas in vitro nas doses de 21,31 e 12,20Gy, respectivamente. A DL50 para a germinação de sementes é 160Gy, enquanto que, para sobrevivência das plântulas, é de 125Gy.

This study had the objective to investigate the effects of gamma ray radiation on survival and proliferation of shoots from stem nodal segments and on the germination seeds passion fruit (Passiflora edulis f. flavicarpa). Stem segments explants (2cm) containing one axillary bud obtained from in vitro-propagated seedlings of passion fruit were treated with γ-rays at dosages ranging from 10 to 60Gy and subsequently transferred to Murashige and Skoog (MS) medium supplemented with 4.0mg L-1BAP. Seeds of passion fruit were irradiated with gamma rays at dosages ranging from 75 to 200Gy. Germination and survival of seedlings were measured after 30 and 60 days of transfer to MS medium, respectively. After 30 days of irradiation of stem segments it was observed 50% reduction in survival of explants and the number of shoots formed in vitro at 21.31 and 12.20Gy, respectively. The LD50 for seed germination is 160Gy, while for seedling survival is 125Gy.

Protective effect of Hizikia fusiforme on radiation-induced damage in splenocytes / 대한수의학회지

The immune system is specifically sensitive to oxidative stress induced by ionizing radiation because of its rapid proliferative activity. For this reason, an instructive immune system is one of the best ways to minimize side effects, such immunodeficiency, of gamma radiation. Over the past few decades, several natural plants with antioxidant and immunomodulatory properties have been identified as adjuncts for nontoxic and successful radiotherapy. Hizikia fusiforme extract (HFE) containing plentiful dietary fiber and fucoidan is known for its instructive antioxidant capacity, immunomodulation abilities, and immune activation. In this study, we determined whether HFE protects radiosensitive immune cells from gamma radiation-induced damage. C57BL/6 mice were irradiated with gamma-ray. The effect of HFE on the ionizing radiation damage of immune cells was then evaluated with an MTT assay, 3H-thymidine incorporation assay, and PI staining. We found that HFE stimulated the proliferation of gamma-ray irradiated immune cells without cytotoxic effects. We also observed that HFE not only decreased DNA damage but also reduced gamma radiation-induced apoptosis of the immune cells. Our results suggest that HFE can protect immune cells from gamma-ray damage and may serve as an effective, non-toxic radioprotective agent.

Three-dimensional conformal radiotherapy shock therapy clinical efficacy of 53 cases of cancer patients with bone metastases / 中国医师进修杂志

Objective To evaluate the curative effect and feasibility of three dimensional conformal radiation therapy for bony metastases,and summarize its indication.Methods Total of 53 patients with bony metastases were received radiotherapy.Results All patienrs were followed up from 3 to 12 month,6 patients discharged from hospital without any therapy,the ratio of change of pain and Clinical symptoms is 88.68％(47/53),the ratio of obviously improvement is 66.04％(35/53),the ratio of improvement is 22.64％(12/53).Conclusion The results show that Three dimensional conformal radiation therapy has obvious advantage and commendable effect on bony metastases.It is a high-performance,save and precise stereotaxis treatment facility.

Nanoparticles improved drug radio protective activity.

Radioprotective agents are synthetic compounds or natural products that are immediately administrated before irradiation to reduce injuries caused by ionizing radiation. Toxicity, short duration, and the unfavorable routes of administration, have prevented the widespread use of most radioprotective agents in practice. This study aimed to evaluate the use of slowly release- long circulation biodegradable polymer Poly(lactide-co-glycolide) (PLGA) as carrier for certain water-soluble radioprotective agents. Penicillamine and Potassium Iodide (KI) were selected as examples of radioprotectors which can be used to protect against both internal radionuclide (chronic radiation exposure) and external-beam irradiation (acute radiation exposure). Emulsion-solvent evaporation method (ESE) was used to prepare hydrophilic-drug loaded PLGA Nanoparticles (PLGA- NPs) in an efficient and reproducible manner. The radioprotective efficacy was assessed by 30 days-survival percentage, relative body weights, and (liver & spleen) total cell counts. Results revealed that single oral administration of Penicillamine-NPs or KINPs was effective as free drug (for 5 successive days) which indicate that PLGA-NPs could be used to modulate radioprotective drug activity in biological system, and to improve drug efficacy in different body organs for longer duration than the equal dose of free drug.

Effect of preconception gamma irradiation on morphometric assessment of adult female mice and embryo / Efecto de la irradiación gamma preconcepción sobre la evaluación morfométrica de ratones hembras adultas y embriones

The aim was to study the effect of preconception gamma irradiation on the gross morphometry of the adult female mice and its embryo. Twenty-seven mice; 18 females and 9 males: subdivided into 3 groups namely (Control, Non-Irradiation and Radiation) containing 6 females and 3 male mice each in 2:1 ratio. A gamma irradiation dose of 1Gy/min was delivered to each batch of mice exposed by a Cobalt 60, Theratron 780c model, by Atomic Energy of Canada Limited (AECL) at the Radiotherapy department of the University College Hospital, Ibadan. All the animals were mated 1 week post irradiation. Vaginal plugs were confirmed, and the pregnant females were sacrificed on day 14 of gestation by chloroform inhalation. The gross morphology of the female mice and their harvested litters were assessed and statistically analysed. A total of 113 embryos were harvested in all groups; 54 for Control, 50 for Non-Irradiated and 9 for the irradiation group. The gross morphologic assessments of the fetuses were statistically significant at P value < 0.05 for all the 3 groups compared. These findings suggest that a preconception irradiation affects the morphology of the female mice and its progeny.

El objetivo fue estudiar el efecto de la irradiación gamma antes de la concepción sobre la morfometría macroscópica de ratones hembra adultos y los embriones de sus crías. Veinte y siete ratones, 18 hembras y 9 machos, divididos en 3 grupos (control, sin irradiación e irradiado) con 6 hembras y 3 machos cada uno en proporción 2:1. Una dosis de radiación gamma de 1 Gy/min fue aplicada a uno de los ratones expuestos por un equipo Cobalt 60, Theratron modelo 780c, Atomic Energy of Canada Limited (AECL) en el departamento de radioterapia del Hospital University College de Ibadan. Todos los animales se aparearon 1 semana después de la irradiación. Se confirmaron los tapones vaginales, y las hembras preñadas fueron sacrificadas en el día 14 de la gestación por inhalación de cloroformo. La morfología general de los ratones hembras y sus camadas fueron evaluadas y analizadas estadísticamente. Un total de 113 embriones se recolectaron en todos los grupos, 54 del grupo control, 50 del grupo no irradiados y 9 del grupo irradiado. Las evaluaciones morfológicas macroscópicas de los fetos fueron estadísticamente significativas (p<0,05) para los 3 grupos de comparación. Estos hallazgos sugieren que una irradiación previa a la concepción afecta a la morfología de los ratones hembra y su progenie.

Estudo de propriedades físico-químicas envolvidas no processo de compactação de uma formulação experimental contendo zidovudina / Study of physical-chemical properties involved in the compaction process of an experimental formulation containing zidovudine

Estudo das propriedades físico-químicas envolvidos no processo de compactação de uma formulação experimental contendo como fármaco modelo a zidovudina. O objetivo foi caracterizar o comportamento físico-químico de comprimidos produzidos por compressão direta usando-se diferentes pressões de compactação. Nas análises foram empregadas metodologias convencionais e não convencionais. A metodologia não convencional foi o uso da técnica da atenuação de raios-gama na determinação da porosidade. As metodologias convencionais utilizadas foram os testes de friabilidade, dureza e dissolução. Os modelos teóricos utilizados para explicar o comportamento físico-químico da formulação sob compressão são os proposto por Heckel e Walker. Os estudos mostraram que o processo de densificação é governado principalmente por deformações do tipo plásticas e pressões em torno de 246MPa são suficientes para induzir deformação plástica e consolidação do sistema compactado. Os resultados da análise de Walker indicam que a formulação tem propriedades de compressão que podem ser melhoradas.

This paper presents a study of the physical-chemical properties involved in powder compaction of an experimental formulation containing as model drug the zidovudine. The aim of this work was to characterize the physical-chemical behavior of experimental tablets produced by direct compression applying different strengths. In these analyses were employed conventional and non-conventional methodologies. The non-convectional methodology was the use of gamma-ray attenuation technique for tablet porosity determination. The conventional methodologies used were the tests of hardness, friability and dissolution. The theoretical models used to explain the physical-chemical behavior of the formulation under compression were those proposed by Heckel and Walker. These tests showing that the densification process is to take mainly by plastic deformation and pressures about 246 MPa are enough to produce robust tablets. Results obtained from the analysis of the Walker equation, indicate that the formulation has compression properties that could be improved.

Establishment of an animal model of severe bone marrow type acute radiation sickness in the BALB/c mice / 肿瘤研究与临床

Objective To establish an animal model of severe bone marrow type acute radiation sickness in the BALB/c mice and to provide a good foundation for further investigation of severe bone marrow type acute radiation sickness.Methods BALB/c mice were given 6.0 Gy 60Co γ-rays total body irradiation.The mice were observed twice a day.The changes in body weight,peripheral blood cell counts were recorded once every three days.Histopathological sections of femur were prepared to observe the histomorphological changes.Bone marrow cells were collected to perform colony cultivation on day 1 before irradiation,and 14 d,28 d after irradiation.Results The mice were less active three days after irradiation,but there were no vomiting and loose stools.The white blood cell counts were dropped to the nadirs (3.0 ％) 11 days after irradiation and recovered to 53.7 ％ on day 28 after irradiation.The platelet counts were dropped to the nadirs (8.1％) 14 days after irradiation and recovered to 60.4 ％ on day 28 after irradiation.Histopathological section showed that the bone marrow cavity was almost empty on day 14 after irradiation.Semi-solid bone marrow cell culture results also demonstrated that CFU-GM and CFU-Mix were obviously decreased.They were not yet fully recovered on day 28 after irradiation.All mice were still alive two months after irradiation.Conclusion A murine model of severe bone marrow type acute radiation sickness has been successfully established by exposure to 6.0 Gy 60Co γ-rays.

Clinical study of stereotactic gamma-ray body radiation therapy for patients with stage Ⅰ / Ⅱ nonsmall cell lung cancer / 中华放射肿瘤学杂志

ObjectiveTo further evaluate the value of the stereotactic gamma-ray body radiation therapy ( γ-SBRT ) for patients with stage Ⅰ / Ⅱ non-small cell lung cancer ( NSCLC ) basing on the preliminary studies.MethodsTwenty-nine eligible patients with stage Ⅰ / Ⅱ NSCLC who is unable or unwilling to receive surgery underwent treatment prospectively with γ-SBRT (OUR-QGD).Patients were fixed by vacuum bag.Each patient underwent slow CT simulation at 5 s/slide with thickness of 5 mm and interval of 5 mm to take into consideration tumor motion.A total dose of 50 Gy was delivered at 5 Gy/fraction to 50％ isodose line covering 100％ of the PTV,with 60 Gy at 6 Gy/fraction to 60％ isodose line covering 90％ of the CTV,70 Gy at 7 Gy/fraction to 70％ isodose line covering 80％ of the GTV,and 10 times finished in 2 weeks,5 fractions per week.ResultsThe follow-up rate was 97％.The 6 month local tumor response rate was 93％,with CR 86％,and PR 7％.The 1-,2-year local control rates were both 93％.The 1-,2-year overall survival rates for the whole group,stage Ⅰ and stage Ⅱ were 97％ and 89％,100％ and 92％,67％ and 67％,respectively.The 1-,2-year progression-free survival were 90％ and 86％,respectively.34％ of the patients had acute radiation toxicities ( grade 1,2 and 3 in 6,2 and 2patients,respectively),and 38％ late radiation toxicities ( grade 1 and 2 in 10 and 1,patients).Conclusions γ-SBRT is a safe and effective treatment regimen,resulted in promising local control and survival with minor toxicity.

Effects of gamma-ray-induced free radicals on the metal content and amino acid composition of human metallothionein-1.

Metallothioneins (MTs), a low-mass class of metalloproteins, are characterized by a high thiolate sulphur and metal content. MTs are involved in metal homeostasis and heavy metal detoxification, and are efficient scavengers of free radicals. This article describes zinc release from human MT-1 and modification of its amino acid composition when subjected to free radicals generated during gamma ray radiolysis. The effect of gamma ray radiolysis of untreated and metal-depleted human MT-1 was tested under multiple aerobic and anaerobic conditions at increasing irradiation doses. Under all conditions, a rapid increase of serine in the early stages of irradiation was observed. Irradiation for longer times led to cysteic acid formation, except under argon atmosphere. Several other amino acid concentrations gradually decreased. Formation of limited amounts of hydroxyproline, hydroxylysine and ornithine as well as some less common derivatives such as cystathionine occurred as side-effects.

Intercomparison of gamma-ray spectrometry analysis of radionuclides in soil samples between China and Japan / 中华放射医学与防护杂志

Objective To test a full range of processes of sample collection,preparation,measurement and analysis by conducting the intercomparison of gamma-ray spectrometry measurement and analysis of radionuclides among key laboratories,so as to facilitate the development of gamma-ray spectrometry measurement and analysis technology.Methods To complete the collection and preparation of soil samples by Chinese Center for Disease Control and Prevention (CDC) laboratory and to measure and analyze the content in two soil samples of 214Pb,214Bi,208TI,228Ac,40K and 137Cs by three laboratories using gamma-ray spectrometry.Results The value calculated by any two laboratories were less than 1 in terms of assessment standards agreed by these three laboratories and based on the activity concentrations and the total uncertainty reported from them.The measurement results from our lab were acceptable.Conclusions Measurement results from these three laboratories are in agreement to some extent.This intercomparison activity has tested the analytical ability of the three laboratories and raised the level of our laboratory in testing homogeneity of sample preparation.

Cytotoxicity of gamma-ray in rat immature hippocampal neurons

This in vitro study evaluated the detrimental effect of acute gamma (gamma)-irradiation on rat immature hippocampal neurons. Rat immature hippocampal neurons (0.5 day in vitro) were irradiated with 0~4 Gy gamma-rays. Cytotoxicity was analyzed using a lactate dehydrogenase release assay at 24 h after gamma-irradiation. Radiation-induced cytotoxicity in immature hippocampal neurons increased in a dose-dependent manner. Pre-treatments of pro-apoptotic caspase inhibitors and anti-oxidative substances significantly blocked gamma-irradiation-induced cytotoxicity in immature hippocampal neurons. The results suggest that the caspase-dependent cytotoxicity of gamma-rays in immature hippocampal cultured neurons may be caused by oxidative stress.

Measurements of the fallout flux of beryllium-7 and its variability in the soil

The aim of this study was to examine the beryllium-7 behavior in the soil. Natural variability of beryllium-7 concentration was calculated to be about 23 percent (relative standard deviation), and the depth distribution could be approximated by an exponential decay in bare soil, with an average penetration depth in the soil about 1 cm. The nuclide was not found below 2 cm depth, which confirmed its utilization to infer the erosion processes as a tracer of soil surface. The maximum beryllium-7 concentration in the analyzed period was about 40 Bq.kg-1.

Berílio-7 é um radionuclídeo cosmogênico, com meia-vida de 53 dias, produzido pelo processo de espalação de átomos de oxigênio e nitrogênio dentro da troposfera e estratosfera. Após sua produção, este é transportado até a superfície terrestre pela deposição úmida e seca. A precipitação seca contribui somente com 3-8 por cento do inventário total. Medidas de berílio-7 no solo podem serem usadas para indicar movimento de solo da camada superficial e este estudo objetiva examinar o comportamento de berílio-7 no solo. Variabilidade natural do inventário de berílio-7 é em torno de 23 por cento (desvio padrão relativo). A distribuição em profundidade de berílio-7 pode ser aproximada por uma função exponencial no solo nu, com uma profundidade média de distribuição no solo em torno de 1 cm. O berílio-7 não foi encontrado abaixo da profundidade de 2 cm para o tipo de solo estudado, o que confirma sua utilização para avaliar processo de erosão superficial como um traçador de solo superficial. A concentração máxima de berílio-7 no período analisado é em torno de 40 Bq.kg-1.