Diethylenetriaminepentaacetic acid (DTPA)-decorated chitosan-coated magnetic silica nanoparticles were synthesized for the adsorptive removal and immobilization of uranium from aqueous media. The synthesized material was abbreviated as NiFeSiCS-D. The NiFeSiCS-D was characterized by TGA, XPS, FT-IR, SEM, XRD and vibrating sample magnetometer. The parameters affecting adsorption including pH, duration of equilibration, initial concentration of uranium and temperature were experimented. The maximum adsorption capacity of uranium was determined to be 208.23 mg g⁻1 at pH 6 by Langmuir adsorption isotherm modeling. Furthermore, the pseudo-second-order kinetics model is fitted for U(VI) uptake process of NiFeSiCS-D adsorption. Moreover, NiFeSiCS-D showed good selective adsorption and regeneration properties for U(VI) after six regeneration cycles. The groups in NiFeSiCS-D acted as electron donors and formed coordination bonds with uranyl ions, leading to the efficient capture of U(VI). This work not only demonstrates a strategy for preparing magnetic nanoparticles with core–shell structure but also provides a promising material for selective uranium adsorption.
Accurate absorbed dose-to-water determination in radiotherapy requires electrometers with calibration coefficients traceable to a primary standards laboratory (PSL). Recent studies have suggested that electrometers of the same model may exhibit sufficiently similar sensitivity characteristics to allow the use of a common electrometer calibration coefficient for quality-control purposes. However, the agreement between a common user-derived coefficient and individual traceable calibration coefficients, and its effect on absorbed dose-to-water uncertainty, have not been quantitatively evaluated. To evaluate the agreement between a common user-derived electrometer calibration coefficient and individual PSL-traceable calibration coefficients, and to assess the resulting influence on absorbed dose-to-water determination and its uncertainty. A multicenter study was conducted involving 12 radiotherapy facilities and 24 combinations of linear accelerators, ionization chambers, and electrometers. All electrometers possessed valid PSL-traceable calibration coefficients. Absorbed dose-to-water values were calculated using both the individual PSL-traceable calibration coefficient (kelec) and a common user-derived coefficient (kelec,user). Direct paired comparisons of kelec and kelec,user were performed for each electrometer, including assessment of metrological compatibility using the normalized error (Eₙ). Dose per monitor unit and uncertainty budgets were compared for 6-MV and 10-MV photon beams. Uncertainty analysis was performed according to the Guide to the Expression of Uncertainty in Measurement (GUM). The mean relative differences between kelec,user and the corresponding individual kelec values ranged from −0.10 to 0.027
Red clay covers in uranium mill tailings (UMTs) impoundments are susceptible to desiccation cracking, compromising radon mitigation. An All-Clay Grout (all-clay-based crack grouting repair material) was developed using attapulgite (ATP) and red clay, without cement or synthetic binders. The optimal ATP content was 5
Plutonium isotope ratios at environmental levels are often reported without any indication of whether an individual measurement is reliable. The uncertainty components of the 240Pu/239Pu atom ratio were apportioned at two signal levels on a single sector-field inductively coupled plasma mass spectrometer (SF-ICP-MS). At high signal, counting statistics dominated. At low signal, procedural-blank subtraction took over, while uranium hydride and mass discrimination stayed minor at both levels. Two dilution series, each prepared from a single homogeneous digest, deviated in opposite directions at low concentration. The low-signal bias therefore depends on the blank subtracted in each measurement sequence rather than on the analyte concentration. The signal-to-blank ratio of the numerator isotope, Rb(240Pu), is proposed as the decision variable. Rb(240Pu) is simply the measured 240Pu signal before blank subtraction divided by the procedural blank of the same sequence. Thresholds can be set by any laboratory with a four-step procedure that requires only its procedural blank and one dilution series, and no isotopic reference material. On the present instrument, ratios with Rb(240Pu) > 10 stayed within a few percent of the undiluted digest. Below Rb(240Pu) = 5, deviations reached tens of percent. The criterion constrains the blank-induced bias within one sequence. Comparability between sequences still depends on in-sequence quality control. Eleven of fourteen surface soils from Northeast China met the criterion. Their mean ratio, 0.193 ± 0.011, agrees with the reported regional mean of 0.192 ± 0.020.
Surface soils from the central Himalayan state of Uttarakhand, India, were evaluated for naturally occurring radionuclides to assess radiological conditions and investigate factors influencing their distribution. The estimated radiological hazard indices were below the recommended limits, indicating negligible radiological risk. Moderate radionuclide enrichment was observed in some districts. Correlations among radionuclides and with rainfall and inorganic carbon were observed which indicate the influence of both geogenic and environmental factors on the spatial variability of natural radioactivity.
