Natural radionuclides are powerful tools for understanding the sources and fate of suspended particulate matter(SPM).Particulate matter with different particle sizes behaves differently with respect to adsorption and ...Natural radionuclides are powerful tools for understanding the sources and fate of suspended particulate matter(SPM).Particulate matter with different particle sizes behaves differently with respect to adsorption and desorption.We analyzed the activi-ties and distribution characteristics of multiple natural radionuclides(238U,226Ra,40K,228Ra,7Be and 210Pbex)on size-fractionated SPM at the Lijin Hydrographic Station(Huanghe or Yellow River)every month over a one-year period.Results showed that medium silt(16–32µm)was the main component.As expected,the activity of each radionuclide decreased with an increase of particle size.We examined the sources of SPM with different particle sizes using activity ratios of 226Ra/238U,228Ra/226Ra,40K/238U and 7Be/210Pbex,and concluded that SPM with different particle sizes originated from different sources.Our results indicate that fine SPM(<32µm)was mainly from the erosion of soil along the lower reaches of the Yellow River,while coarse SPM(>32µm)was mainly derived from resuspension of riverbed sediment.During high runoff periods,the concentration of SPM increased significantly,and the pro-portion of fine particles originating upstream increased.Naturally occurring radioactive isotopes,especially on size-fractionated par-ticles,are therefore seen as useful tracers to understand the sources and behaviors of riverine particles transported from land to sea.展开更多
A novel and fast three-dimensional reconstruction method for a Compton camera and its performance in radionuclide imaging is proposed and analyzed in this study. The conical surface sampling back-projection method wit...A novel and fast three-dimensional reconstruction method for a Compton camera and its performance in radionuclide imaging is proposed and analyzed in this study. The conical surface sampling back-projection method with scattering angle correction(CSS-BP-SC) can quickly perform the back-projection process of the Compton cone and can be used to precompute the list-mode maximum likelihood expectation maximization(LM-MLEM). A dedicated parallel architecture was designed for the graphics processing unit acceleration of the back-projection and iteration stage of the CSS-BP-SC-based LM-MLEM. The imaging results of the two-point source Monte Carlo(MC) simulation demonstrate that by analyzing the full width at half maximum along the three coordinate axes, the CSS-BP-SC-based LM-MLEM can obtain imaging results comparable to those of the traditional reconstruction algorithm, that is, the simple back-projection-based LM-MLEM. The imaging results of the mouse phantom MC simulation and experiment demonstrate that the reconstruction results obtained by the proposed method sufficiently coincide with the set radioactivity distribution, and the speed increased by more than 664 times compared to the traditional reconstruction algorithm in the mouse phantom experiment. The proposed method will further advance the imaging applications of Compton cameras.展开更多
BACKGROUND Radionuclides produce Cherenkov radiation(CR),which can potentially activate photosensitizers(PSs)in phototherapy.Several groups have studied Cherenkov energy transfer to PSs using optical imaging;however,c...BACKGROUND Radionuclides produce Cherenkov radiation(CR),which can potentially activate photosensitizers(PSs)in phototherapy.Several groups have studied Cherenkov energy transfer to PSs using optical imaging;however,cost-effectively identifying whether PSs are excited by radionuclide-derived CR and detecting fluorescence emission from excited PSs remain a challenge.Many laboratories face the need for expensive dedicated equipment.AIM To cost-effectively confirm whether PSs are excited by radionuclide-derived CR and distinguish fluorescence emission from excited PSs.METHODS The absorbance and fluorescence spectra of PSs were measured using a microplate reader and fluorescence spectrometer to examine the photo-physical properties of PSs.To mitigate the need for expensive dedicated equipment and achieve the aim of the study,we developed a method that utilizes a chargecoupled device optical imaging system and appropriate long-pass filters of different wavelengths(manual sequential application of long-pass filters of 515,580,645,700,750,and 800 nm).Tetrakis(4-carboxyphenyl)porphyrin(TCPP)was utilized as a model PS.Different doses of copper-64(^(64)CuCl_(2))(4,2,and 1 mCi)were used as CR-producing radionuclides.Imaging and data acquisition were performed 0.5 h after sample preparation.Differential image analysis was conducted by using ImageJ software(National Institutes of Health)to visually evaluate TCPP fluorescence.RESULTS The maximum absorbance of TCPP was at 390-430 nm,and the emission peak was at 670 nm.The CR and CRinduced TCPP emissions were observed using the optical imaging system and the high-transmittance long-pass filters described above.The emission spectra of TCPP with a peak in the 645-700 nm window were obtained by calculation and subtraction based on the serial signal intensity(total flux)difference between^(64)CuCl_(2)+TCPP and^(64)CuCl_(2).Moreover,the differential fluorescence images of TCPP were obtained by subtracting the^(64)CuCl_(2)image from the^(64)CuCl_(2)+TCPP image.The experimental results considering different^(64)CuCl_(2)doses showed a dosedependent trend.These results demonstrate that a bioluminescence imaging device coupled with different longpass filters and subtraction image processing can confirm the emission spectra and differential fluorescence images of CR-induced TCPP.CONCLUSION This simple method identifies the PS fluorescence emission generated by radionuclide-derived CR and can contribute to accelerating the development of Cherenkov energy transfer imaging and the discovery of new PSs.展开更多
AIM:To investigate the feasibility of radionuclide therapy of colon tumor cells by baculovirus vector-mediated transfer of the sodium/iodide symporter(NIS) gene.METHODS:A recombinant baculovirus plasmid carrying the N...AIM:To investigate the feasibility of radionuclide therapy of colon tumor cells by baculovirus vector-mediated transfer of the sodium/iodide symporter(NIS) gene.METHODS:A recombinant baculovirus plasmid carrying the NIS gene was constructed,and the viruses(BacNIS) were prepared using the Bac-to-Bac system.The infection efficiency in the colon cancer cell line SW1116 of a green fluorescent protein(GFP) expressing baculovirus(Bac-GFP) at different multiplicities of infection(MOI) with various concentrations of sodium butyrate was determined by flow cytometry.An in vitro cytotoxicity assay was also conducted after infection of SW1116 cells with Bac-NIS.Iodine uptake of Bac-NIS infected SW1116 cells and inhibition of this uptake by sodium perchlorate was examined,and the effect of Bac-NISmediated 131 I in killing tumor cells was evaluated by cell colony formation tests.RESULTS:Infection and transgene expression in SW1116with Bac-GFP were significantly enhanced by sodium butyrate,as up to 72% of SW1116 cells were infected with the virus at MOI of 400 and sodium butyrate at 0.5 mmol/L.No obvious cytotoxicity was observed under these conditions.Infection of SW1116 with Bac-NIS allowed uptake of 131 I in these tumor cells,which could be inhibited by sodium perchlorate.The viability of SW1116 cells infected with Bac-NIS was significantly lower than with Bac-GFP,suggesting that NIS gene-mediated 131 I uptake could specifically kill tumor cells.CONCLUSION:Baculovirus vector-mediated NIS gene therapy is a potential approach for treatment of colon cancer.展开更多
This paper describes the interaction between deep-seated landslides and man-made structures such as dams, penstocks, viaducts, and tunnels. Selected case studies are reported first with the intent to gain insights int...This paper describes the interaction between deep-seated landslides and man-made structures such as dams, penstocks, viaducts, and tunnels. Selected case studies are reported first with the intent to gain insights into the complexities associated with the interaction of these structures with deep-seated landslides(generally referred to as deep-seated gravity slope deformations, DSGSDs). The main features, which characterize these landslides, are mentioned together with the interaction problems encountered in each case. Given the main objective of this paper, the numerical modeling methods adopted are outlined as means for increase in the understanding of the interaction problems being investigated. With the above in mind, the attention moves to an important and unique case history dealing with the interaction of a large-size twin-tunnel excavated with an earth pressure balance(EPB)tunnel boring machine(TBM) and a deep-seated landslide, which was reactivated due to the stress changes induced by tunnel excavation in landslide shear zone. The geological and geotechnical conditions are described together with the available monitoring data on the landslide movements, based on the advanced and conventional monitoring tools used. Numerical modeling is illustrated as an aid to back-analyze the monitored surface and subsurface deformations and to assist in finding the appropriate engineering solution for putting the tunnel into service and as a follow-up means for future understanding and control of the interaction problems. The simulation is based on a novel time-dependent model representing the landslide behavior.展开更多
Ionizing Radiation emitted from radionuclide has an adverse effect on human health. A continuing population exposure to naturally occurring radioactive materials (NORMS) found in our environment is one of the major sc...Ionizing Radiation emitted from radionuclide has an adverse effect on human health. A continuing population exposure to naturally occurring radioactive materials (NORMS) found in our environment is one of the major scientific subjects that attract public attention. The assessment of radionuclide content of shore sediments of river Benue-North Central Nigeria was carried out using gamma-ray spectrometry. The activity concentrations of U-238, Th-232 and K-40 were found to have an average concentration of 1.17, 3.31 and 405.95 Bq·kg-1 respectively. The values gotten from present study were compared with the world average values. World average values of U-238, Th-232 and K-40 are 50 Bq·kg-1, 50 Bq·kg-1 and 500 Bq·kg-1 respectively. The mean concentration of daughter radionuclides generated from U-238, Th-232 was 4.32, 10.37, 5.24, 3.86, 11.87, and 6.52 for Bi-212, Pb-212, Bi-214, Pb-214, Ra-226 and Ac-228, respectively. The mean of the absorbed dose, Annual effective dose equivalent, for radium equivalent activity, and external hazard index, were evaluated to be 19.45 nGy·h-1, 23.82 μSv·y-1, 37.16 Bq·kg-1, 0.10 mSv·y1, below the permissible limit of 57 nGy·h-1, 70 μSv·y-1, 370 Bq·kg-1 and 1 mSv·y-1 respectively. These shore sediments from river Benue are therefore, radiologically safe for construction and other domestic and industrial purposes.展开更多
Contamination of land could occur during the extraction and handling of materials containing high levels of naturally occurring radionuclide materials. These radionuclides find their ways into the food chain. The acti...Contamination of land could occur during the extraction and handling of materials containing high levels of naturally occurring radionuclide materials. These radionuclides find their ways into the food chain. The activity concentrations of natural radionuclides 40K, 226Ra, and 232Th in heart, liver, kidney, lungs, spleen and beef of cattle slaughtered and consumed in a tin mining area of Jos Plateau, Nigeria were determined by gamma ray spectroscopy method. The activity concentration of 40K is the highest in all the samples. The annual effective dose to man through the ingestion of the radionuclides in the organs was estimated. The mean annual effective doses calculated are 35.35 ± 13.84, 57.89 ± 38.27 and 46.93 ± 10.28 μSv?y?1 for heart, liver and kidney, respectively. Those of lungs, spleen and meat are 28.44 ± 15.70, 48.34 ± 28.85 and 41.24 ± 3.56 μSv?y?1, respectively. These are of the order of two magnitudes higher than those obtained for food in Abeokuta, Nigeria.展开更多
The radioactivity measurements in food crops and their diet derivatives and farm soil samples from Abeokuta, one of the elevated background radiation areas in Nigeria have been carried out in order to determine the co...The radioactivity measurements in food crops and their diet derivatives and farm soil samples from Abeokuta, one of the elevated background radiation areas in Nigeria have been carried out in order to determine the concentration levels of natural radionuclides (40K, 226Ra and 232Th). The activity concentrations of the natural radionuclides in the samples were determined via gamma-ray spectrometry using a 76 mm × 76 mm NaI(Tl) detector. Different common food crops representing the major sources of dietary requirements to the local population were collected for the measurements. The collected food crops were prepared into their different derivable composite diets using preparation techniques locale to the population. Using available food consumption data and the activity concentrations of the radionuclides, the ingestion effective doses were evaluated for the food crops and diet types per preparation techniques. For the tuberous food crop samples, the annual ingestion effective doses in the raw and different composite diets were 0.02 - 0.04 μSv and cumulatively 0.04 - 0.05 μSv while in the non-tuberous crops the doses were 0.44 - 0.70 μSv and cumulatively greater than 1 μSv respectively. Results of the study indicate that method of diet preparation is seen to play a major role in population ingestion dose reduction especially for tuberous crops than in non-tuberous crops. The study also showed that more ingestion dose could be incurred in diets prepared by roasting techniques. The result of the study will serve as a useful radiometric data for future epidemiological studies in the area and for food safety regulations and policy implementations in the country.展开更多
A severe accident in a marine nuclear reactor leads to radionuclide leakage,which causes hidden dangers to workers and has adverse effects of environmental pollution.It is necessary to propose a novel approach to radi...A severe accident in a marine nuclear reactor leads to radionuclide leakage,which causes hidden dangers to workers and has adverse effects of environmental pollution.It is necessary to propose a novel approach to radionuclide diffusion in a confined environment after a severe accident in a marine nuclear reactor.Therefore,this study proposes a new method for the severe accident analysis program MELCOR coupled with computational fluid dynamics scSTREAM to study radioactive diffusion in severe accidents.The radionuclide release fraction and temperature calculated by MELCOR were combined with the scSTREAM calculations to study the radionuclide diffusion behavior and the phenomenon of radionuclide diffusion in different space environments of the reactor under the conditions of varying wind velocities of the ventilation system and diffusion speed.The results show that the wind velocity of the ventilation system is very small or zero,and the turbulent diffusion of radionuclides is not obvious and diffuses slowly in the form of condensation sedimentation and gravity settlement.When the wind speed of the ventilation system increases,the flow of radionuclides meets the wall and forms eddy currents,affecting the time variation of radionuclides diffusing into chamber 2.The wind velocity of the ventilation system and the diffusion speed has opposite effects on the time variation trend of radionuclide diffusion into the four chambers.展开更多
This study proposes a novel feature extraction approach for radionuclide identification to increase the precision of identification of the gamma-ray energy spectrum set.For easier utilization of the information contai...This study proposes a novel feature extraction approach for radionuclide identification to increase the precision of identification of the gamma-ray energy spectrum set.For easier utilization of the information contained in the spectra,the vectors of the gamma-ray energy spectra from Euclidean space,which are fingerprints of the different types of radionuclides,were mapped to matrices in the Banach space.Subsequently,to make the spectra in matrix form easier to apply to image-based deep learning frameworks,the matrices of the gamma-ray energy spectra were mapped to images in the RGB color space.A deep convolutional neural network(DCNN)model was constructed and trained on the ImageNet dataset.The mapped gamma-ray energy spectrum images were applied as inputs to the DCNN model,and the corresponding outputs of the convolution layers and fully connected layers were transferred as descriptors of the images to construct a new classification model for radionuclide identification.The transferred image descriptors consist of global and local features,where the activation vectors of fully connected layers are global features,and activations from convolution layers are local features.A series of comparative experiments between the transferred image descriptors,peak information,features extracted by the histogram of the oriented gradients(HOG),and scale-invariant feature transform(SIFT)using both synthetic and measured data were applied to 11 classical classifiers.The results demonstrate that although the gamma-ray energy spectrum images are completely unfamiliar to the DCNN model and have not been used in the pre-training process,the transferred image descriptors achieved good classification results.The global features have strong semantic information,which achieves an average accuracy of 92.76%and 94.86%on the synthetic dataset and measured dataset,respectively.The results of the statistical comparison of features demonstrate that the proposed approach outperforms the peak-searching-based method,HOG,and SIFT on the synthetic and measured datasets.展开更多
The steeply sloping agricultural highlands in Korea have severe soil erosion.Estimation of both soil erosion and sedimentation in these highlands is necessary to make plans for soil-conservation measures,but it is not...The steeply sloping agricultural highlands in Korea have severe soil erosion.Estimation of both soil erosion and sedimentation in these highlands is necessary to make plans for soil-conservation measures,but it is not feasible using existing soil-erosion models.This study measured the site-specific concentrations of ^(137)Cs and ^(210)Pb_(ex) on both a highland slope(33%slope)and a reference site(undisturbed flat area)to estimate soil erosion and redistribution.The use of the fallout radionuclide(FRN)method was evaluated to see if it is a suitable method for characterizing soil erosion.Results were compared with those obtained with the Universal Soil Loss Equation(USLE),which is an empirical model that estimates annual soil erosion.The average concentrations of ^(137)Cs and ^(210)Pb_(ex) at the reference site were 11.57±0.24 Bq kg^(-1) and 59.74±4.2 Bq kg^(-1),respectively.Concentrations of ^(137)Cs and ^(210)Pb_(ex) in the experimental slope were 16.4%and 10.8%,respectively,of those at the reference site.Radionuclide inventories were lower at the upper point of the slope than those at the basal point of the slope.Concentrations of ^(137)Cs and ^(210)Pb_(ex) were significantly correlated with available phosphorus,organic matter,CEC,and exchangeable cations.Estimation of soil redistribution rate using ^(137)Cs and ^(210)Pb_(ex) showed site-specific variations at different points along the slope,and respective ranges were^(-1)7.46~-207.51 and 1.55~-581.38 Mgha^(-1) yr^(-1),which indicated that more erosion was assessed by ^(210)Pb_(ex) than by ^(137)Cs.Redistribution analysis showed that soil erosion occurred along the entire slope,except for the bottom point of the slope where 1.55 Mgha^(-1) yr^(-1) of sediment accumulated.The USLE provided a single value of the average annual soil loss in the entire slope,which was either 166 or 398 Mgha^(-1) yr^(-1),depending on the soil erodibility factor(soil series factor and calculated factor from soil sample analysis)used in the model.We conclude that the FRN method using ^(137)Cs and ^(210)Pb_(ex) radionuclides can be used to assess soil erosion and redistribution in steeply sloping agricultural highlands.Verification of soil-erosion values using the FRN method and soil-erosion models has been controversial,but it merits further study at many locations with different soils,topography,and management practices.展开更多
The study of the radionuclide distribution in sediment is a very important aspect in environmental impact of the low level radioactive liquid waste (LLW) from coastal nuclear facilities or nuclear power plant. Even no...The study of the radionuclide distribution in sediment is a very important aspect in environmental impact of the low level radioactive liquid waste (LLW) from coastal nuclear facilities or nuclear power plant. Even now we do not know much about it. In this paper, a simple and useful method is put forward and it is used to estimate the nuclide distribution in sediment. The result showed that the LLW from nuclear facility or nuclear power plant will do a little harm to the sediment nearby. But the harm is not very serious. Much works have to be done before full understanding of the situation.展开更多
Unsaturated radionuclide migration experiments were conducted in a pit inside thetesting hall.Several types of radionuclides were used in the experiments.Tritium wasused as a tracer for water movement in unsaturated l...Unsaturated radionuclide migration experiments were conducted in a pit inside thetesting hall.Several types of radionuclides were used in the experiments.Tritium wasused as a tracer for water movement in unsaturated loess.Other kinds of radionuclideswere also used in order to obtain fundamental parameters for radionuclide migration sothat further environmental assessment of low—level radioactive waste disposal can be car-ried out.Mechanisms governing unsaturated flow in loess,that is,principles ofone—way lateral flow,are presented qualitatively in this paper.And a continuumone—dimensional model for radionuclide migration testing is developed based on the ex-periments conducted under the particular conditions at the test site.The data measuredfrom the tests were compared with solutions of this one—dimensional model.Resultsshow that this model is feasible for modeling radionuclide migration in unsaturatedloess.展开更多
A wide spectrum of scenarios may lead to radiation incidents and the liberation of radioactive material. In the case of a terrorist attack by a "dirty bomb", there is a risk of mechanical and thermal trauma,...A wide spectrum of scenarios may lead to radiation incidents and the liberation of radioactive material. In the case of a terrorist attack by a "dirty bomb", there is a risk of mechanical and thermal trauma, external irradiation, superficial contamination and incorporation of radioactive material. The first treatment priority must be given to the care of trauma patients with life-threatening injuries, as the health effects of radiation occur with latency. Radionuclide incorporation will lead to a longer-lasting irradiation from inside the body, associated with a higher risk of stochastic radiation effects(e.g., occurrence of tumors) in the long run. It must be expected that victims with potentially incorporated radionuclides will far outnumber trauma patients. The elimination of radionuclides can be enhanced by the administration of decorporation agents such as(Ca) Diethylenetriaminepentaacetic acid(DTPA) or Prussian blue,reducing the radiological burden of the body. There is still no consensus whether decorporation treatment should be started immediately based only on a suspicion of radionuclide incorporation("urgent approach") or if the results of internal dosimetry confirming the necessity of a treatment should be awaited, accepting the delay caused by the measurements and computations("precautionary approach"). As the therapeutic effectiveness may be substantially decreased if treatment initiation is delayed only by several days, depending on the radionuclide, the physicochemical properties of the compounds involved and the route of absorption, we favor an "urgent approach" from a medical point of view. In doubt, it seems justified to treat victims by precaution, as the adverse effects of the medication seem minimal. However, in the case of a high number of victims, an "urgent treatment approach" may require a large number of daily doses of antidotes, and therefore, adequate investments in preparedness and antidote stockpiling are necessary.展开更多
For over one hundred years, viruses have been recognized as capable of killing tumor cells. At present, people are still researching and constructing more suitable oncolytic viruses for treating different malignant tu...For over one hundred years, viruses have been recognized as capable of killing tumor cells. At present, people are still researching and constructing more suitable oncolytic viruses for treating different malignant tumors. Although extensive studies have demonstrated that herpes simplex virus type 1 (HSV-1) is the most potential oncolytic virus, therapies based on herpes simplex virus type 1 vectors still arouse bio-safety and risk management issues. Researchers have therefore introduced the new idea of treating cancer with HSV-1 mutants labeled with radionuclides, combining radionuclide and oncolytic virus therapies. This overview briefly summarizes the status and mechanisms by which oncolytic viruses kill tumor cells, discusses the application of HSV-1 and HSV-1 derived vectors for tumor therapy, and demonstrates the feasibility and prospect of HSV-1 mutants labeled with radionuclides for treating tumors.展开更多
The routine and potential future applications of equilibrium radionuclide angiocardiography/multigated acquisition (MUGA) in clinical decision making are explored in this review. The non-invasive nature of the test, l...The routine and potential future applications of equilibrium radionuclide angiocardiography/multigated acquisition (MUGA) in clinical decision making are explored in this review. The non-invasive nature of the test, less operator dependence, lower radiation dose and ease of performing, even in ill patients, are important considerations in clinical cardiology practice. Two important routine uses of this modality in day-to-day clinical practice include the following: serial assessment of left ventricular ejection fraction (LVEF) in patients receiving cardiotoxic chemotherapy, and determination of accurate LVEF in patients with intractable heart failure. Other potential utilities of MUGA that could be translated into clinical practice include determination of regional LVEF, obtaining information about both right and left ventricle in suitable patients as a part of first pass angiocardiography, identification of diastolic dysfunction in patients with heart failure with preserved LVEF, and demonstration of dyssynchrony prior to cardiac resynchronisation, specifically by MUGA single photon emission tomography.The last two indications are particularly important and evolving at this point.展开更多
Whole body bone scan imaging of <sup>99m</sup>Tc-MDP was performed in 80 casesfrom Sept 1991 to Feb 1992. Among them 20 patients showed negtive bone imaging and56 patients showed positive bone imaging. The...Whole body bone scan imaging of <sup>99m</sup>Tc-MDP was performed in 80 casesfrom Sept 1991 to Feb 1992. Among them 20 patients showed negtive bone imaging and56 patients showed positive bone imaging. There were false-positive bone imaging in 4 pa-tients. Bone scan imaging has been regarded as a useful method in the early diagnosis ofshelatal disease, especially in old patients with bone metastasis. But the final confirmationof malignancy should be still cautious.展开更多
Fifty-six patients with chest pain underwent selective coronaryangiography,radionuclide ventriculography (RNV) and frequency domaincardiography (FCG) to evaluate left ventricular function in coronary artery dis-ease (...Fifty-six patients with chest pain underwent selective coronaryangiography,radionuclide ventriculography (RNV) and frequency domaincardiography (FCG) to evaluate left ventricular function in coronary artery dis-ease (CAD).The sensitivity,specificity and accuracy of FCG were 87.5%,77.8%and 82.9%,respectively,which were slightly less than those of RNV (92.5%,88.9% and 90.8%,respectively).The changes of FCG scores were negatively corre-lated with changes of LVEF (r=-0.586,P【0.01),and TS (r=-0.679,P【0.01).These results indicate that FCG may be useful for the evaluation of leftventricular function in patients with CAD.展开更多
Discharges from the Mining-and-Chemical Com- bine (MCC) of Rosatom, downstream from Krasnoyarsk-26, near of the Krasnoyarsk resulted in radioactive contamination of sedi-ments of the River Yenisei. The concentration o...Discharges from the Mining-and-Chemical Com- bine (MCC) of Rosatom, downstream from Krasnoyarsk-26, near of the Krasnoyarsk resulted in radioactive contamination of sedi-ments of the River Yenisei. The concentration of artificial gammaemitting radionuclides (137Cs, 60Co, 152Eu, and 241Am) was determined to analyze the migration processes leading to the transport of these radionuclides. The concentration of artificial radionuclides in the surface layers of the studied area varied in wide ranges: 137Cs – 318 - 1800 Bq/kg, 60Co – 87 - 720 Bq/kg, 152Eu – 12 - 287 Bq/kg and 241Am – 6 - 76 Bq/kg. There was a sequence of migration of radionuclides investigated in the surface layer of sedi-ments that were collected in the near zone of influence of the MCC: 241Am ≈ 152Eu >60Co >137Cs. Radionuclide species have been found to be directly related to sediment structure and composition.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.U22A20580,42130410,and U1906210)the Fundamental Research Funds for the Central Universities(No.201962003).
文摘Natural radionuclides are powerful tools for understanding the sources and fate of suspended particulate matter(SPM).Particulate matter with different particle sizes behaves differently with respect to adsorption and desorption.We analyzed the activi-ties and distribution characteristics of multiple natural radionuclides(238U,226Ra,40K,228Ra,7Be and 210Pbex)on size-fractionated SPM at the Lijin Hydrographic Station(Huanghe or Yellow River)every month over a one-year period.Results showed that medium silt(16–32µm)was the main component.As expected,the activity of each radionuclide decreased with an increase of particle size.We examined the sources of SPM with different particle sizes using activity ratios of 226Ra/238U,228Ra/226Ra,40K/238U and 7Be/210Pbex,and concluded that SPM with different particle sizes originated from different sources.Our results indicate that fine SPM(<32µm)was mainly from the erosion of soil along the lower reaches of the Yellow River,while coarse SPM(>32µm)was mainly derived from resuspension of riverbed sediment.During high runoff periods,the concentration of SPM increased significantly,and the pro-portion of fine particles originating upstream increased.Naturally occurring radioactive isotopes,especially on size-fractionated par-ticles,are therefore seen as useful tracers to understand the sources and behaviors of riverine particles transported from land to sea.
基金supported by the National Natural Science Foundation of China (No. 12220101005)Natural Science Foundation of Jiangsu Province (No. BK20220132)+2 种基金Primary Research and Development Plan of Jiangsu Province (No. BE2019002-3)Fundamental Research Funds for Central Universities (No. NG2022004)the Foundation of the Graduate Innovation Center in NUAA (No. xcxjh20210613)。
文摘A novel and fast three-dimensional reconstruction method for a Compton camera and its performance in radionuclide imaging is proposed and analyzed in this study. The conical surface sampling back-projection method with scattering angle correction(CSS-BP-SC) can quickly perform the back-projection process of the Compton cone and can be used to precompute the list-mode maximum likelihood expectation maximization(LM-MLEM). A dedicated parallel architecture was designed for the graphics processing unit acceleration of the back-projection and iteration stage of the CSS-BP-SC-based LM-MLEM. The imaging results of the two-point source Monte Carlo(MC) simulation demonstrate that by analyzing the full width at half maximum along the three coordinate axes, the CSS-BP-SC-based LM-MLEM can obtain imaging results comparable to those of the traditional reconstruction algorithm, that is, the simple back-projection-based LM-MLEM. The imaging results of the mouse phantom MC simulation and experiment demonstrate that the reconstruction results obtained by the proposed method sufficiently coincide with the set radioactivity distribution, and the speed increased by more than 664 times compared to the traditional reconstruction algorithm in the mouse phantom experiment. The proposed method will further advance the imaging applications of Compton cameras.
基金This study was reviewed and approved by the Institutional Review Board of National Institutes for Quantum Science and Technology,No.07-1064-28.No animals or animal-derived samples or patients or patient-derived samples were included in this study.
文摘BACKGROUND Radionuclides produce Cherenkov radiation(CR),which can potentially activate photosensitizers(PSs)in phototherapy.Several groups have studied Cherenkov energy transfer to PSs using optical imaging;however,cost-effectively identifying whether PSs are excited by radionuclide-derived CR and detecting fluorescence emission from excited PSs remain a challenge.Many laboratories face the need for expensive dedicated equipment.AIM To cost-effectively confirm whether PSs are excited by radionuclide-derived CR and distinguish fluorescence emission from excited PSs.METHODS The absorbance and fluorescence spectra of PSs were measured using a microplate reader and fluorescence spectrometer to examine the photo-physical properties of PSs.To mitigate the need for expensive dedicated equipment and achieve the aim of the study,we developed a method that utilizes a chargecoupled device optical imaging system and appropriate long-pass filters of different wavelengths(manual sequential application of long-pass filters of 515,580,645,700,750,and 800 nm).Tetrakis(4-carboxyphenyl)porphyrin(TCPP)was utilized as a model PS.Different doses of copper-64(^(64)CuCl_(2))(4,2,and 1 mCi)were used as CR-producing radionuclides.Imaging and data acquisition were performed 0.5 h after sample preparation.Differential image analysis was conducted by using ImageJ software(National Institutes of Health)to visually evaluate TCPP fluorescence.RESULTS The maximum absorbance of TCPP was at 390-430 nm,and the emission peak was at 670 nm.The CR and CRinduced TCPP emissions were observed using the optical imaging system and the high-transmittance long-pass filters described above.The emission spectra of TCPP with a peak in the 645-700 nm window were obtained by calculation and subtraction based on the serial signal intensity(total flux)difference between^(64)CuCl_(2)+TCPP and^(64)CuCl_(2).Moreover,the differential fluorescence images of TCPP were obtained by subtracting the^(64)CuCl_(2)image from the^(64)CuCl_(2)+TCPP image.The experimental results considering different^(64)CuCl_(2)doses showed a dosedependent trend.These results demonstrate that a bioluminescence imaging device coupled with different longpass filters and subtraction image processing can confirm the emission spectra and differential fluorescence images of CR-induced TCPP.CONCLUSION This simple method identifies the PS fluorescence emission generated by radionuclide-derived CR and can contribute to accelerating the development of Cherenkov energy transfer imaging and the discovery of new PSs.
基金Supported by Grants from the National Natural Science Foundation of China,No.30570525the Shanghai Leading Academic Discipline Project,No.S30203
文摘AIM:To investigate the feasibility of radionuclide therapy of colon tumor cells by baculovirus vector-mediated transfer of the sodium/iodide symporter(NIS) gene.METHODS:A recombinant baculovirus plasmid carrying the NIS gene was constructed,and the viruses(BacNIS) were prepared using the Bac-to-Bac system.The infection efficiency in the colon cancer cell line SW1116 of a green fluorescent protein(GFP) expressing baculovirus(Bac-GFP) at different multiplicities of infection(MOI) with various concentrations of sodium butyrate was determined by flow cytometry.An in vitro cytotoxicity assay was also conducted after infection of SW1116 cells with Bac-NIS.Iodine uptake of Bac-NIS infected SW1116 cells and inhibition of this uptake by sodium perchlorate was examined,and the effect of Bac-NISmediated 131 I in killing tumor cells was evaluated by cell colony formation tests.RESULTS:Infection and transgene expression in SW1116with Bac-GFP were significantly enhanced by sodium butyrate,as up to 72% of SW1116 cells were infected with the virus at MOI of 400 and sodium butyrate at 0.5 mmol/L.No obvious cytotoxicity was observed under these conditions.Infection of SW1116 with Bac-NIS allowed uptake of 131 I in these tumor cells,which could be inhibited by sodium perchlorate.The viability of SW1116 cells infected with Bac-NIS was significantly lower than with Bac-GFP,suggesting that NIS gene-mediated 131 I uptake could specifically kill tumor cells.CONCLUSION:Baculovirus vector-mediated NIS gene therapy is a potential approach for treatment of colon cancer.
基金support of Spea Ingegneria Europea SpA and Società Autostrade per l’Italia SpA
文摘This paper describes the interaction between deep-seated landslides and man-made structures such as dams, penstocks, viaducts, and tunnels. Selected case studies are reported first with the intent to gain insights into the complexities associated with the interaction of these structures with deep-seated landslides(generally referred to as deep-seated gravity slope deformations, DSGSDs). The main features, which characterize these landslides, are mentioned together with the interaction problems encountered in each case. Given the main objective of this paper, the numerical modeling methods adopted are outlined as means for increase in the understanding of the interaction problems being investigated. With the above in mind, the attention moves to an important and unique case history dealing with the interaction of a large-size twin-tunnel excavated with an earth pressure balance(EPB)tunnel boring machine(TBM) and a deep-seated landslide, which was reactivated due to the stress changes induced by tunnel excavation in landslide shear zone. The geological and geotechnical conditions are described together with the available monitoring data on the landslide movements, based on the advanced and conventional monitoring tools used. Numerical modeling is illustrated as an aid to back-analyze the monitored surface and subsurface deformations and to assist in finding the appropriate engineering solution for putting the tunnel into service and as a follow-up means for future understanding and control of the interaction problems. The simulation is based on a novel time-dependent model representing the landslide behavior.
文摘Ionizing Radiation emitted from radionuclide has an adverse effect on human health. A continuing population exposure to naturally occurring radioactive materials (NORMS) found in our environment is one of the major scientific subjects that attract public attention. The assessment of radionuclide content of shore sediments of river Benue-North Central Nigeria was carried out using gamma-ray spectrometry. The activity concentrations of U-238, Th-232 and K-40 were found to have an average concentration of 1.17, 3.31 and 405.95 Bq·kg-1 respectively. The values gotten from present study were compared with the world average values. World average values of U-238, Th-232 and K-40 are 50 Bq·kg-1, 50 Bq·kg-1 and 500 Bq·kg-1 respectively. The mean concentration of daughter radionuclides generated from U-238, Th-232 was 4.32, 10.37, 5.24, 3.86, 11.87, and 6.52 for Bi-212, Pb-212, Bi-214, Pb-214, Ra-226 and Ac-228, respectively. The mean of the absorbed dose, Annual effective dose equivalent, for radium equivalent activity, and external hazard index, were evaluated to be 19.45 nGy·h-1, 23.82 μSv·y-1, 37.16 Bq·kg-1, 0.10 mSv·y1, below the permissible limit of 57 nGy·h-1, 70 μSv·y-1, 370 Bq·kg-1 and 1 mSv·y-1 respectively. These shore sediments from river Benue are therefore, radiologically safe for construction and other domestic and industrial purposes.
文摘Contamination of land could occur during the extraction and handling of materials containing high levels of naturally occurring radionuclide materials. These radionuclides find their ways into the food chain. The activity concentrations of natural radionuclides 40K, 226Ra, and 232Th in heart, liver, kidney, lungs, spleen and beef of cattle slaughtered and consumed in a tin mining area of Jos Plateau, Nigeria were determined by gamma ray spectroscopy method. The activity concentration of 40K is the highest in all the samples. The annual effective dose to man through the ingestion of the radionuclides in the organs was estimated. The mean annual effective doses calculated are 35.35 ± 13.84, 57.89 ± 38.27 and 46.93 ± 10.28 μSv?y?1 for heart, liver and kidney, respectively. Those of lungs, spleen and meat are 28.44 ± 15.70, 48.34 ± 28.85 and 41.24 ± 3.56 μSv?y?1, respectively. These are of the order of two magnitudes higher than those obtained for food in Abeokuta, Nigeria.
文摘The radioactivity measurements in food crops and their diet derivatives and farm soil samples from Abeokuta, one of the elevated background radiation areas in Nigeria have been carried out in order to determine the concentration levels of natural radionuclides (40K, 226Ra and 232Th). The activity concentrations of the natural radionuclides in the samples were determined via gamma-ray spectrometry using a 76 mm × 76 mm NaI(Tl) detector. Different common food crops representing the major sources of dietary requirements to the local population were collected for the measurements. The collected food crops were prepared into their different derivable composite diets using preparation techniques locale to the population. Using available food consumption data and the activity concentrations of the radionuclides, the ingestion effective doses were evaluated for the food crops and diet types per preparation techniques. For the tuberous food crop samples, the annual ingestion effective doses in the raw and different composite diets were 0.02 - 0.04 μSv and cumulatively 0.04 - 0.05 μSv while in the non-tuberous crops the doses were 0.44 - 0.70 μSv and cumulatively greater than 1 μSv respectively. Results of the study indicate that method of diet preparation is seen to play a major role in population ingestion dose reduction especially for tuberous crops than in non-tuberous crops. The study also showed that more ingestion dose could be incurred in diets prepared by roasting techniques. The result of the study will serve as a useful radiometric data for future epidemiological studies in the area and for food safety regulations and policy implementations in the country.
基金supported by the Postgraduate Scientific Research Innovation Project of Hunan Province (No. CX20210922)
文摘A severe accident in a marine nuclear reactor leads to radionuclide leakage,which causes hidden dangers to workers and has adverse effects of environmental pollution.It is necessary to propose a novel approach to radionuclide diffusion in a confined environment after a severe accident in a marine nuclear reactor.Therefore,this study proposes a new method for the severe accident analysis program MELCOR coupled with computational fluid dynamics scSTREAM to study radioactive diffusion in severe accidents.The radionuclide release fraction and temperature calculated by MELCOR were combined with the scSTREAM calculations to study the radionuclide diffusion behavior and the phenomenon of radionuclide diffusion in different space environments of the reactor under the conditions of varying wind velocities of the ventilation system and diffusion speed.The results show that the wind velocity of the ventilation system is very small or zero,and the turbulent diffusion of radionuclides is not obvious and diffuses slowly in the form of condensation sedimentation and gravity settlement.When the wind speed of the ventilation system increases,the flow of radionuclides meets the wall and forms eddy currents,affecting the time variation of radionuclides diffusing into chamber 2.The wind velocity of the ventilation system and the diffusion speed has opposite effects on the time variation trend of radionuclide diffusion into the four chambers.
基金supported by the National Defense Fundamental Research Project(No.JCKY2020404C004)Sichuan Science and Technology Program(No.22NSFSC0044).
文摘This study proposes a novel feature extraction approach for radionuclide identification to increase the precision of identification of the gamma-ray energy spectrum set.For easier utilization of the information contained in the spectra,the vectors of the gamma-ray energy spectra from Euclidean space,which are fingerprints of the different types of radionuclides,were mapped to matrices in the Banach space.Subsequently,to make the spectra in matrix form easier to apply to image-based deep learning frameworks,the matrices of the gamma-ray energy spectra were mapped to images in the RGB color space.A deep convolutional neural network(DCNN)model was constructed and trained on the ImageNet dataset.The mapped gamma-ray energy spectrum images were applied as inputs to the DCNN model,and the corresponding outputs of the convolution layers and fully connected layers were transferred as descriptors of the images to construct a new classification model for radionuclide identification.The transferred image descriptors consist of global and local features,where the activation vectors of fully connected layers are global features,and activations from convolution layers are local features.A series of comparative experiments between the transferred image descriptors,peak information,features extracted by the histogram of the oriented gradients(HOG),and scale-invariant feature transform(SIFT)using both synthetic and measured data were applied to 11 classical classifiers.The results demonstrate that although the gamma-ray energy spectrum images are completely unfamiliar to the DCNN model and have not been used in the pre-training process,the transferred image descriptors achieved good classification results.The global features have strong semantic information,which achieves an average accuracy of 92.76%and 94.86%on the synthetic dataset and measured dataset,respectively.The results of the statistical comparison of features demonstrate that the proposed approach outperforms the peak-searching-based method,HOG,and SIFT on the synthetic and measured datasets.
基金This research was supported in part by Research Grant from Kangwon National University(No.520160156:2016)the Korea Ministry of Environment,with the strategic EcoSSSoil Project,KEITI(Korea Environmental Industry and Technology Institute),Korea(Grant No.2019002820004).
文摘The steeply sloping agricultural highlands in Korea have severe soil erosion.Estimation of both soil erosion and sedimentation in these highlands is necessary to make plans for soil-conservation measures,but it is not feasible using existing soil-erosion models.This study measured the site-specific concentrations of ^(137)Cs and ^(210)Pb_(ex) on both a highland slope(33%slope)and a reference site(undisturbed flat area)to estimate soil erosion and redistribution.The use of the fallout radionuclide(FRN)method was evaluated to see if it is a suitable method for characterizing soil erosion.Results were compared with those obtained with the Universal Soil Loss Equation(USLE),which is an empirical model that estimates annual soil erosion.The average concentrations of ^(137)Cs and ^(210)Pb_(ex) at the reference site were 11.57±0.24 Bq kg^(-1) and 59.74±4.2 Bq kg^(-1),respectively.Concentrations of ^(137)Cs and ^(210)Pb_(ex) in the experimental slope were 16.4%and 10.8%,respectively,of those at the reference site.Radionuclide inventories were lower at the upper point of the slope than those at the basal point of the slope.Concentrations of ^(137)Cs and ^(210)Pb_(ex) were significantly correlated with available phosphorus,organic matter,CEC,and exchangeable cations.Estimation of soil redistribution rate using ^(137)Cs and ^(210)Pb_(ex) showed site-specific variations at different points along the slope,and respective ranges were^(-1)7.46~-207.51 and 1.55~-581.38 Mgha^(-1) yr^(-1),which indicated that more erosion was assessed by ^(210)Pb_(ex) than by ^(137)Cs.Redistribution analysis showed that soil erosion occurred along the entire slope,except for the bottom point of the slope where 1.55 Mgha^(-1) yr^(-1) of sediment accumulated.The USLE provided a single value of the average annual soil loss in the entire slope,which was either 166 or 398 Mgha^(-1) yr^(-1),depending on the soil erodibility factor(soil series factor and calculated factor from soil sample analysis)used in the model.We conclude that the FRN method using ^(137)Cs and ^(210)Pb_(ex) radionuclides can be used to assess soil erosion and redistribution in steeply sloping agricultural highlands.Verification of soil-erosion values using the FRN method and soil-erosion models has been controversial,but it merits further study at many locations with different soils,topography,and management practices.
文摘The study of the radionuclide distribution in sediment is a very important aspect in environmental impact of the low level radioactive liquid waste (LLW) from coastal nuclear facilities or nuclear power plant. Even now we do not know much about it. In this paper, a simple and useful method is put forward and it is used to estimate the nuclide distribution in sediment. The result showed that the LLW from nuclear facility or nuclear power plant will do a little harm to the sediment nearby. But the harm is not very serious. Much works have to be done before full understanding of the situation.
文摘Unsaturated radionuclide migration experiments were conducted in a pit inside thetesting hall.Several types of radionuclides were used in the experiments.Tritium wasused as a tracer for water movement in unsaturated loess.Other kinds of radionuclideswere also used in order to obtain fundamental parameters for radionuclide migration sothat further environmental assessment of low—level radioactive waste disposal can be car-ried out.Mechanisms governing unsaturated flow in loess,that is,principles ofone—way lateral flow,are presented qualitatively in this paper.And a continuumone—dimensional model for radionuclide migration testing is developed based on the ex-periments conducted under the particular conditions at the test site.The data measuredfrom the tests were compared with solutions of this one—dimensional model.Resultsshow that this model is feasible for modeling radionuclide migration in unsaturatedloess.
文摘A wide spectrum of scenarios may lead to radiation incidents and the liberation of radioactive material. In the case of a terrorist attack by a "dirty bomb", there is a risk of mechanical and thermal trauma, external irradiation, superficial contamination and incorporation of radioactive material. The first treatment priority must be given to the care of trauma patients with life-threatening injuries, as the health effects of radiation occur with latency. Radionuclide incorporation will lead to a longer-lasting irradiation from inside the body, associated with a higher risk of stochastic radiation effects(e.g., occurrence of tumors) in the long run. It must be expected that victims with potentially incorporated radionuclides will far outnumber trauma patients. The elimination of radionuclides can be enhanced by the administration of decorporation agents such as(Ca) Diethylenetriaminepentaacetic acid(DTPA) or Prussian blue,reducing the radiological burden of the body. There is still no consensus whether decorporation treatment should be started immediately based only on a suspicion of radionuclide incorporation("urgent approach") or if the results of internal dosimetry confirming the necessity of a treatment should be awaited, accepting the delay caused by the measurements and computations("precautionary approach"). As the therapeutic effectiveness may be substantially decreased if treatment initiation is delayed only by several days, depending on the radionuclide, the physicochemical properties of the compounds involved and the route of absorption, we favor an "urgent approach" from a medical point of view. In doubt, it seems justified to treat victims by precaution, as the adverse effects of the medication seem minimal. However, in the case of a high number of victims, an "urgent treatment approach" may require a large number of daily doses of antidotes, and therefore, adequate investments in preparedness and antidote stockpiling are necessary.
基金National Natural Science Foundation of China, No. 30770604
文摘For over one hundred years, viruses have been recognized as capable of killing tumor cells. At present, people are still researching and constructing more suitable oncolytic viruses for treating different malignant tumors. Although extensive studies have demonstrated that herpes simplex virus type 1 (HSV-1) is the most potential oncolytic virus, therapies based on herpes simplex virus type 1 vectors still arouse bio-safety and risk management issues. Researchers have therefore introduced the new idea of treating cancer with HSV-1 mutants labeled with radionuclides, combining radionuclide and oncolytic virus therapies. This overview briefly summarizes the status and mechanisms by which oncolytic viruses kill tumor cells, discusses the application of HSV-1 and HSV-1 derived vectors for tumor therapy, and demonstrates the feasibility and prospect of HSV-1 mutants labeled with radionuclides for treating tumors.
文摘The routine and potential future applications of equilibrium radionuclide angiocardiography/multigated acquisition (MUGA) in clinical decision making are explored in this review. The non-invasive nature of the test, less operator dependence, lower radiation dose and ease of performing, even in ill patients, are important considerations in clinical cardiology practice. Two important routine uses of this modality in day-to-day clinical practice include the following: serial assessment of left ventricular ejection fraction (LVEF) in patients receiving cardiotoxic chemotherapy, and determination of accurate LVEF in patients with intractable heart failure. Other potential utilities of MUGA that could be translated into clinical practice include determination of regional LVEF, obtaining information about both right and left ventricle in suitable patients as a part of first pass angiocardiography, identification of diastolic dysfunction in patients with heart failure with preserved LVEF, and demonstration of dyssynchrony prior to cardiac resynchronisation, specifically by MUGA single photon emission tomography.The last two indications are particularly important and evolving at this point.
文摘Whole body bone scan imaging of <sup>99m</sup>Tc-MDP was performed in 80 casesfrom Sept 1991 to Feb 1992. Among them 20 patients showed negtive bone imaging and56 patients showed positive bone imaging. There were false-positive bone imaging in 4 pa-tients. Bone scan imaging has been regarded as a useful method in the early diagnosis ofshelatal disease, especially in old patients with bone metastasis. But the final confirmationof malignancy should be still cautious.
文摘Fifty-six patients with chest pain underwent selective coronaryangiography,radionuclide ventriculography (RNV) and frequency domaincardiography (FCG) to evaluate left ventricular function in coronary artery dis-ease (CAD).The sensitivity,specificity and accuracy of FCG were 87.5%,77.8%and 82.9%,respectively,which were slightly less than those of RNV (92.5%,88.9% and 90.8%,respectively).The changes of FCG scores were negatively corre-lated with changes of LVEF (r=-0.586,P【0.01),and TS (r=-0.679,P【0.01).These results indicate that FCG may be useful for the evaluation of leftventricular function in patients with CAD.
文摘Discharges from the Mining-and-Chemical Com- bine (MCC) of Rosatom, downstream from Krasnoyarsk-26, near of the Krasnoyarsk resulted in radioactive contamination of sedi-ments of the River Yenisei. The concentration of artificial gammaemitting radionuclides (137Cs, 60Co, 152Eu, and 241Am) was determined to analyze the migration processes leading to the transport of these radionuclides. The concentration of artificial radionuclides in the surface layers of the studied area varied in wide ranges: 137Cs – 318 - 1800 Bq/kg, 60Co – 87 - 720 Bq/kg, 152Eu – 12 - 287 Bq/kg and 241Am – 6 - 76 Bq/kg. There was a sequence of migration of radionuclides investigated in the surface layer of sedi-ments that were collected in the near zone of influence of the MCC: 241Am ≈ 152Eu >60Co >137Cs. Radionuclide species have been found to be directly related to sediment structure and composition.