Uranium, perhaps the most strategically important component of heavy minerals, finds particular significance in the nuclear industry. In prospecting trenches, the radioactivity of 238U and 232Th ...provides a good signature of the presence of heavy minerals. In the work herein, the activity concentrations of several key primordial radionuclides (238U, 232Th, and 40K) were measured in prospecting trenches (each of the latter being of approximately the same geometry and physical situation). All of these are located in the Seila area of the South Eastern desert of Egypt. A recently introduced industry standard, the portable hand-held RS-230 BGO gamma-ray spectrometer (1024 channels) was employed in the study. Based on the measured data, the trenches were classified as either non-regulated (U activity less than 1000 Bq kg-1) or regulated (with 238U activity more than 1000 Bq kg-1). Several radiological hazard parameters were calculated, statistical analysis also being performed to examine correlations between the origins of the radionuclides and their influence on the calculated values. While the radioactivity and hazard parameters exceed United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) guided limits, the mean annual effective doses of 0.49 and 1.4 mSv y-1 in non-regulated and regulated trenches respectively remain well below the International Commission on Radiological Protection (ICRP) recommended 20 mSv/y maximum occupational limit. This investigation reveals that the studied area contains high uranium content, suitable for extraction of U-minerals for use in the nuclear fuel cycle.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Study is made of the radioactivity in the beach sands of Langkawi island, a well-known tourist destination. Investigation is made of the relative presence of the naturally occurring radionuclide 40K ...and the natural-series indicator radionuclides 226Ra and 232Th, the gamma radiation exposure also being estimated. Sample quantities of black and white sand were collected for gamma ray spectrometry, yielding activity concentration in black sands of 226Ra, 232Th and 40K from 451±9 to 2411±65Bqkg−1 (mean of 1478Bqkg−1); 232±4 to 1272±35Bqkg−1 (mean of 718Bqkg−1) and 61±6 to 136±7Bqkg−1 (mean of 103Bqkg−1) respectively. Conversely, in white sands the respective values for 226Ra and 232Th were appreciably lower, at 8.3±0.5 to 13.7±1.4Bqkg−1 (mean of 9.8Bqkg−1) and 4.5±0.7 to 9.4±1.0Bqkg−1 (mean of 5.9Bqkg−1); 40K activities differed insubstantially from that in black sands, at 85±4 to 133±7Bqkg−1 with a mean of 102Bqkg−1. The mean activity concentrations of 226Ra and 232Th in black sands are comparable with that of high background areas elsewhere in the world. The heavy minerals content gives rise to elevated 226Ra and 232Th activity concentrations in all of black sand samples. Evaluation of the various radiological risk parameters points to values which in some cases could be in excess of recommendations providing for safe living and working. Statistical analysis examines correlations between the origins of the radionuclides, also identifying and classifying the radiological parameters. Present results may help to form an interest in rare-earth resources for the electronics industry, power generation and the viability of nuclear fuels cycle resources.
•Reference data of NORMs in beach sand of Langkawi Island is reported.•All radiological hazard indices for heavy mineral rich beach sand are found higher than the permissible limit.•Presence of monazite rich black sand is the reason for enrichment of UNat and ThNat.•Measured data may form an interest in rare-earth resources for electronics industry and nuclear fuels cycle resources.
Natural molecular machines contain protein components that undergo motion relative to each other. Designing such mechanically constrained nanoscale protein architectures with internal degrees of ...freedom is an outstanding challenge for computational protein design. Here we explore the de novo construction of protein machinery from designed axle and rotor components with internal cyclic or dihedral symmetry. We find that the axle-rotor systems assemble in vitro and in vivo as designed. Using cryo-electron microscopy, we find that these systems populate conformationally variable relative orientations reflecting the symmetry of the coupled components and the computationally designed interface energy landscape. These mechanical systems with internal degrees of freedom are a step toward the design of genetically encodable nanomachines.
Recognizing the large neutron capture cross section of boron, the suitability of boron containing resources are studied for protection against nuclear radiation. Experimental and simulation study for ...neutron (thermal and fast) and gamma-ray shielding features of six different types of boron containing natural materials, obtained from the utilization process of boron ores in Liaoning Province of China, are performed here. Shielding ability of B1-B6 for thermal neutron is mainly based on the on the absorption cross section of boron; The elements with higher content or cross section have higher contribution for the fast neutron shielding; The interactions of B1-B6 with gamma rays are different with each other because of the difference components, but the mainly are Photoelectric Absorption in the low energy region, Incoherent Scattering in the intermediate energy region and Pair Production in nuclear filed in the high energy region, the elements with higher content or high atomic number show higher contribution for the shielding performance. The neutron and gamma ray shielding show a positive correlation with the boron content and material density, respectively. Comprehensive shielding performance of the studied samples is found to be better than some commercial materials. Overall, the composites prepared by boron containing resources and epoxy resin show excellent shielding performances for neutron but poor for gamma rays. Particularly, the boron rich slag shows the greater performance for both neutron and gamma ray shielding. The obtained results show the pathway for potential use of boron containing resources as structural materials in the radiation environment, and provide protection to both radiation worker and general populace from harmful nuclear radiation.
•Neutron shielding features depend on elements with higher content and cross section.•Gamma ray shielding depends on the element with higher content and atomic number.•Shielding properties of B1-B6 are better than some other commercial materials.•Boron rich slag is the best one for both neutron and gamma ray shielding.
An evaluation of the radioactivity levels associated with naturally occurring radioactive materials has been undertaken as part of a systematic study to provide a surface radiological map of the ...State of Kuwait. Soil samples from across Kuwait were collected, measured and analysed in the current work. These evaluations provided soil activity concentration levels for primordial radionuclides, specifically members of the 238U and 232Th decay chains and 40K which. The 238U and 232Th chain radionuclides and 40K activity concentration values ranged between 5.9 ↔ 32.3, 3.5 ↔ 27.3, and 74 ↔ 698 Bq/kg respectively. The evaluated average specific activity concentrations of 238U, 232Th and 40K across all of the soil samples have mean values of 18, 15 and 385 Bq/kg respectively, all falling below the worldwide mean values of 35, 40 and 400 Bq/kg respectively. The radiological risk factors are associated with a mean of 33.16 ± 2.46 nG/h and 68.5 ± 5.09 Bq/kg for the external dose rate and Radium equivalent respectively. The measured annual dose rates for all samples gives rise to a mean value of 40.8 ± 3.0 μSv/y while the internal and internal hazard indices have been found to be 0.23 ± 0.02 and 0.19 ± 0.01 respectively.
•Measurements made using high-resolution gamma-ray spectrometry for activity concentrations of 238U, 232Th and 40K involving 184 analysed soil samples.•The distribution of 40K is observed to remain rather constant across the entire region of Kuwait.•Results obtained indicate higher 238U/232Th ratio in the northern region relative to southern one.•Measured radiological risk factors across the wider Kuwait environment are below world mean values.
The authors report on the clinical activity of a new oral inhibitor of Janus kinase 2 (JAK2) in patients with myelofibrosis. The drug improved a wide range of symptoms promptly, controlled them for ...>1 year, and appeared to inhibit disease progression to acute leukemia.
Myelofibrosis is manifested as primary myelofibrosis, post–essential thrombocythemia myelofibrosis, or post–polycythemia vera myelofibrosis and is characterized by clinical signs (e.g., progressive anemia, bone marrow fibrosis, and splenomegaly) and a constellation of debilitating symptoms (fatigue, weakness, bone pain, a hypercatabolic state, and weight loss).
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Survival in myelofibrosis is related to the number of risk factors and ranges from 2 to 4 years among patients with two or more risk factors (intermediate-2 or high risk) to 8 to 11 years among patients with no risk factors or one risk factor (intermediate-1 or low risk) (see Table 1A in the Supplementary Appendix, available with . . .
Radiation pneumonitis is a dose-limiting toxicity for patients undergoing concurrent chemoradiation therapy (CCRT) for non-small cell lung cancer (NSCLC). We performed an individual patient data ...meta-analysis to determine factors predictive of clinically significant pneumonitis.
After a systematic review of the literature, data were obtained on 836 patients who underwent CCRT in Europe, North America, and Asia. Patients were randomly divided into training and validation sets (two-thirds vs one-third of patients). Factors predictive of symptomatic pneumonitis (grade ≥2 by 1 of several scoring systems) or fatal pneumonitis were evaluated using logistic regression. Recursive partitioning analysis (RPA) was used to define risk groups.
The median radiation therapy dose was 60 Gy, and the median follow-up time was 2.3 years. Most patients received concurrent cisplatin/etoposide (38%) or carboplatin/paclitaxel (26%). The overall rate of symptomatic pneumonitis was 29.8% (n=249), with fatal pneumonitis in 1.9% (n=16). In the training set, factors predictive of symptomatic pneumonitis were lung volume receiving ≥20 Gy (V(20)) (odds ratio OR 1.03 per 1% increase, P=.008), and carboplatin/paclitaxel chemotherapy (OR 3.33, P<.001), with a trend for age (OR 1.24 per decade, P=.09); the model remained predictive in the validation set with good discrimination in both datasets (c-statistic >0.65). On RPA, the highest risk of pneumonitis (>50%) was in patients >65 years of age receiving carboplatin/paclitaxel. Predictors of fatal pneumonitis were daily dose >2 Gy, V(20), and lower-lobe tumor location.
Several treatment-related risk factors predict the development of symptomatic pneumonitis, and elderly patients who undergo CCRT with carboplatin-paclitaxel chemotherapy are at highest risk. Fatal pneumonitis, although uncommon, is related to dosimetric factors and tumor location.
In recent times, the security focus for civil aviation has shifted from hijacking in the 1980s, towards deliberate sabotage. X-ray imaging provides a major tool in checked baggage inspection, with ...various sensitive techniques being brought to bear in determining the form, and density of items within luggage as well as other material dependent parameters. This review first examines the various challenges to X-ray technology in securing a safe system of passenger transportation. An overview is then presented of the various conventional and less conventional approaches that are available to the airline industry, leading to developments in state-of-the-art imaging technology supported by enhanced machine and observer-based decision making principles.
► Contemporary review of X-ray explosives detection techniques for checked baggage. ► Post 9/11 challenges to X-ray technology and screening are considered. ► State-of-the-art imaging technology and decision making principles described.
Malaysia, a rapidly growing industrial country, is susceptible to pollution via large-scale industrial engagements and associated human activities. One particular concern is the potential impact upon ...the quality of locally resourced vegetables, foodstuffs that contain important nutrients necessary for good health, forming an essential part of the Malaysian diet. As a part of this, it is of importance for there to be accurate knowledge of radioactive material uptake in these vegetables, not least in respect of any public health detriment. Herein, using HPGe γ-ray spectrometry, quantification has been performed of naturally occurring radionuclides in common edible vegetables and their associated soils. From samples analyses, the soil activity concentration ranges (in units of Bq/kg) for 226Ra, 232Th and 40K were respectively 1.33–30.90, 0.48–26.80, 7.99–136.5 while in vegetable samples the ranges were 0.64–3.80, 0.21–6.91, 85.53–463.8. Using the corresponding activities, the transfer factors (TFs) from soil-to-vegetables were estimated, the transfers being greatest for 40K, an expected outcome given the essentiality of this element in support of vigorous growth. The TFs of 226Ra and 232Th were found to be in accord with available literature data, the values indicating the mobility of these radionuclides to be low in the studied soils. Committed effective dose and the associated life-time cancer risk was estimated, being found to be below the permissible limit proposed by UNSCEAR. Results for the studied media show that the prevalent activities and mobilities pose no significant threat to human health, the edible vegetables being safe for consumption.
•Assessment of radionuclides transfer from soil-to-edible flora in Malaysia.•The estimated TFs for 226,228Ra show greater values than the literature data for vegetables.•The Highland farms present greater concentrations than the ground farms.•Committed effective dose and life-time cancer risk found below the permissible limit by UNSCEAR.
The plasma focus device discussed herein is a Z-pinch pulsed-plasma arrangement. In this, the plasma is heated and compressed into a cylindrical column, producing a typical density of > 1025 ...particles/m3 and a temperature of (1-3) × 107 oC. The plasma focus has been widely investigated as a radiation source, including as ion-beams, electron-beams and as a source of x-ray and neutron production, providing considerable scope for use in a variety of technological situations. Thus said, the nature of the radiation emission depends on the dynamics of the plasma pinch. In this study of the characteristics of deuteron-beam emission, in terms of energy, fluence and angular distribution were analyzed. The 2.7 kJ plasma focus discharge has been made to operate at a pressure of less than 1 mbar rather than at its more conventional operating pressure of a few mbar. Faraday cup were used to determine deuteron-beam energy and deuteron-beam fluence per shot while CR-39 solid-state nuclear track detectors were employed in studying the angular distribution of deuteron emission. Beam energy and deuteron-beam fluence per shot have been found to be pressure dependent. The largest value of average deuteron energy measured for present conditions was found to be (52 ± 7) keV, while the deuteron-beam fluence per shot was of the order of 1015 ions/m2 when operated at a pressure of 0.2 mbar. The deuteron-beam emission is in the forward direction and is observed to be highly anisotropic.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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