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[en] Polygonum perfoliatum L. is a Mn-tolerant plant as considered having the potential to revegetate in manganese mine wasteland. The glasshouse experiments were carried out to evaluate its tolerance and physiological response in different Mn concentrations (5, 500, 1000, 2000, 5000, and 10,000 μmol L−1). Absorption bands of P. perfoliatum differed greatly in lipids, proteins, and carbohydrates. With elevated levels of Mn (5–2000 μmol L−1), absorbance changed little, which demonstrated that lower Mn concentrations had negligible influence on transport functions. As Mn concentrations in excess of 2000 μmol L−1, absorbance increased slightly but eventually decreased. Furthermore, a hydroponic culture was carried out in order to study its changes of ultrastructure with the increasing Mn concentrations (5, 1000, and 10,000 μmol L−1). Lower Mn levels with 5 and 1000 μmol L−1 had no breakage function to the ultrastructure of P. perfoliatum. However, as Mn concentration was up to 10,000 μmol L−1, visible damages began to appear, the quantity of mitochondria in root cells increased, and the granum lamellae of leaf cell chloroplasts presented a disordered state. In comparison with the controls, black agglomerations were found in the cells of P. perfoliatum under the controlling concentration of Mn with 1000 and 10,000 μmol L−1 for 30 days, which became obvious at higher Mn concentrations. As Mn concentration was 10,000 μmol L−1, a kind of new acicular substance was developed in leaf cells and intercellular spaces, possibly indicating a resistance mechanism in P. perfoliatum. These results confirm that P. perfoliatum shows potential for the revegetation of abandoned manganese tailings.
[en] Concentration of [18F]fluoride has been mentioned in literature, however, reports have lacked details about system designs, operation, and performance. Here, we describe in detail a compact, fast, fully-automated concentration system based on a micro-sized strong anion exchange cartridge. The concentration of radionuclides enables scaled-up microfluidic synthesis. Our system can also be used to provide highly concentrated [18F]fluoride with minimal water content. We demonstrate how the concentrator can produce varying concentrations of [18F]fluoride for the macroscale synthesis of N-boc-5-[18F]fluoroindole without an azeotropic drying process, while enabling high starting radioactivity. By appropriate choice of solid-phase resin, flow conditions, and eluent solution, we believe this approach can be extended beyond [18F]fluoride to other radionuclides.
[en] Highlights: • The pre-dose effect on TL and OSL from α-Al2O3:C,Mg and α-Al2O3:C is reported. • TL/OSL dose responses of α-Al2O3:C,Mg is unaffected by pre-dose up to 1000 Gy. • TL/OSL dose responses of α-Al2O3:C is affected by pre-dose. • The concentration of deep traps in α-Al2O3:C,Mg is less than that in α-Al2O3:C. - Abstract: We report the effect of pre-dose on the thermoluminescence (TL) and optically stimulated luminescence (OSL) dose response of α-Al2O3:C,Mg and α-Al2O3:C. Before any luminescence measurement, the samples were irradiated with different doses, namely 100, 500 and 1000 Gy to populate the deep electron traps. This is the pre-dose. The results from TL and OSL studies are compared with results from samples used without any pre-measurement dose. The TL glow curves and OSL decay curves of α-Al2O3:C,Mg recorded after pre-doses of 100, 500 and 1000 Gy are identical to those from a sample used without any pre-dose. Further, the TL and OSL dose response of all α-Al2O3:C,Mg samples are similar regardless of pre-dose. In comparison, the TL glow curves and OSL decay curves of α-Al2O3:C are influenced by pre-dose. We conclude that the differences in the TL and OSL dose response of various pre-dosed samples of α-Al2O3:C are due to the concentration of charge in the deep traps. On the other hand, owing to the lower concentration of such deep traps in α-Al2O3:C,Mg, the TL or OSL dose responses are not affected by pre-dose in this material.
[en] The Old Rifle Site is a former vanadium and uranium ore-processing facility located adjacent to the Colorado River and approximately 0.3 miles east of the city of Rifle, CO. The former processing facilities have been removed and the site uranium mill tailings are interned at a disposal cell north of the city of Rifle. However, some low level remnant uranium contamination still exists at the Old Rifle site. In 2002, the United States Nuclear Regulatory Commission (US NRC) concurred with United States Department of Energy (US DOE) on a groundwater compliance strategy of natural flushing with institutional controls to decrease contaminant concentrations in the aquifer. In addition to active monitoring of contaminant concentrations, the site is also used for DOE Legacy Management (LM) and other DOE-funded small-scale field tests of remediation technologies. The purpose of this laboratory scale study was to evaluate the effectiveness of a hydroxyapatite (Ca10(PO4)6(OH)2) permeable reactive barrier and source area treatment in Old Rifle sediments. Phosphate treatment impact was evaluated by comparing uranium leaching and surface phase changes in untreated to PO4-treated sediments. The impact of the amount of phosphate precipitation in the sediment on uranium mobility was evaluated with three different phosphate loadings. A range of flow velocity and uranium concentration conditions (i.e., uranium flux through the phosphate-treated sediment) was also evaluated to quantify the uranium uptake mass and rate by the phosphate precipitate.
[en] Highlights: • Attenuation method was proposed to calculate leak rate. • Bench method was proposed to calculate the effective generation rate. • The methods were applied in an radon chamber. - Abstract: A radon chamber is a standard apparatus for experimental research of radon that can simulate ambient conditions such as atmosphere, ground surface and subsurface, and the dynamic stabilization technology of radon concentration in a radon chamber is the core technology of radon chamber research. In this paper, an attenuation method was proposed based on a radon leakage attenuation model for calculation of leak rate, a kernel parameter of the stabilization technology of radon concentration in a closed radon chamber, as well as a bench method based on a radon replenishment model for calculation of the effective generation rate at radon source, another kernel parameter of stabilization technology. In this study, the present methods were applied to parameter calculation in an HD-6-type small/medium-sized radon chamber, achieving an excellent application effect.
[en] Highlights: • Inhaled radon risk to the health of the employees. • Radon concentrations in the hot springs. • Radon content reduction in thermal spas consists of diluting the geothermal water concentration with fresh water. • Hot springs negative aspect is not confirmed by experimental result (below 20 mSv a-1). - Abstract: Inhaled radon and its progenies induce health concern due to high activity-concentration in selected thermal spas of Boyacá region. Hydrogeothermal water sources in a high risk seismic area, are studied to determine by water bubbling method radon concentration values; their occurrence is between few hundreds and 2000 Bq dm−3. Deposits, existing in this area, reach at the surface soil gas radon concentration up to 210 kBq m−3. Maintenance workers, health tourists and visitor's possible detrimental health effects, are discussed in relation to radon balneotherapy beneficial aspects.
[en] The present study investigated accumulation, translocation and tolerance of autotrophic Populus alba clone “Villafranca” in response to excess concentrations of cadmium (Cd) and copper (Cu) provided to the plants. For this purpose, increasing concentrations of Cd (0, 5, 50 and 250 μM) and Cu (0, 5, 50, 250 and 500 μM) were administered to the growth medium in which micropropagated poplar plantlets were exposed to metal treatments for 15 days. Filter bags, instead of the conventional in vitro screening, were applied to improve the experimental design. Results showed that Cd and Cu increased in shoots and roots at increasing metal concentration in the medium. The highest Cd content was found in leaves, while the highest Cu content was found in roots. In “Villafranca”, Cu showed toxic effects on the development of the seedlings, especially at the highest concentrations, reducing plant dry mass. However, the tolerance index (Ti) indicated good tolerance in this clone under exposure to excess metal concentrations, whereas plants had higher translocation factor (Tf). We recommend in vitro selection of tolerant genotypes, aimed at providing early indication on accumulation potentiality and tolerance capability in research on plant sensitivity to excess heavy metal concentrations.
[en] Highlights: • Electronic properties of bilayer graphene are investigated by exploring doping of a single or both layers. • Random tight-binding model and the coherent potential approximation are implemented. • Behavior of p or n doping is resulted in a conventional semiconductor, dependent on impurity type and concentration. - Abstract: In the framework of the Green's functions approach, random tight-binding model and using the coherent potential approximation, electronic characteristics of the bilayer graphene are investigated by exploring various forms of substitutional doping of a single or both layers of the system by either boron and (or) nitrogen atoms. The results for displacement of the Fermi level resemble the behavior of acceptor or donor doping in a conventional semiconductor, dependent on the impurity type and concentration. The particular pattern of doping of just one layer with one impurity type is most efficient for opening a gap within the energy bands which could be tuned directly by impurity concentration. Doping both layers at the same time, each with one impurity type, leads to an anomaly whereby the gap decreases with increasing impurity concentration.
[en] Through the method of changing Sr concentration in solid medium gradually, 26 strains bacteria and 20 strains actinomyces were isolated from the strontium contaminated soil. Four strains of strontium-resistance bacteria have been selected by the further studies in liquid culture. Magnifications of four bacteria concentration are all more than 30 times and adsorption rates of Sr are more than 20%. The study results show that the bacteria's optimum growth condition are pH = 6.0-7.5, θ = 20-40 ℃, ρ0(Sr) = 0-2.0 g/L. Identification results show that the microorganism are all subject to Bacillus according to analysis results of 16S rDNA. (authors)