The lanthanide elements and isotopes are analytes of significant interest for several nuclear-related fields, for example nuclear waste treatment, nuclear forensics, and nuclear safeguards. Chemical ...separation among these elements is uniquely challenging due to their nearly identical chemical properties. This difficulty in interelement separation can create obstacles for quantitative radiometric analysis, specifically for isotopes without distinct energy emissions easily measured by gamma spectrometry, e.g.
161
Tb. This work presents an optimized method for the isolation of individual rare earth elements using LN resin.
Light-induced rotation of absorbing microscopic particles by transfer of angular momentum from light to the material raises the possibility of optically driven micromachines. The phenomenon has been ...observed using elliptically polarized laser beams or beams with helical phase structure,. But it is difficult to develop high power in such experiments because of overheating and unwanted axial forces, limiting the achievable rotation rates to a few hertz. This problem can in principle be overcome by using transparent particles, transferring angular momentum by a mechanism first observed by Beth in 1936, when he reported a tiny torque developed in a quartz 'wave-plate' owing to the change in polarization of transmitted light. Here we show that an optical torque can be induced on microscopic birefringent particles of calcite held by optical tweezers. Depending on the polarization of the incident beam, the particles either become aligned with the plane of polarization (and thus can be rotated through specified angles) or spin with constant rotation frequency. Because these microscopic particles are transparent, they can be held in three-dimensional optical traps at very high power without heating, leading to rotation rates of over 350 Hz.
The March 11, 2011 9.0 magnitude undersea megathrust earthquake off the coast of Japan and subsequent tsunami waves triggered a major nuclear event at the Fukushima Dai-ichi nuclear power station. At ...the time of the event, units 1, 2, and 3 were operating and units 4, 5, and 6 were in a shutdown condition for maintenance. Loss of cooling capacity to the plants along with structural damage caused by the earthquake and tsunami resulted in a breach of the nuclear fuel integrity and release of radioactive fission products to the environment. Fission products started to arrive in the United States via atmospheric transport on March 15, 2011 and peaked by March 23, 2011. Atmospheric activity concentrations of 131I reached levels of 3.0×10−2Bqm−3 in Melbourne, FL. The noble gas 133Xe reached atmospheric activity concentrations in Ashland, KS of 17Bqm−3. While these levels are not health concerns, they were well above the detection capability of the radionuclide monitoring systems within the International Monitoring System of the Comprehensive Nuclear-Test-Ban Treaty.
The determination of 161Tb activity is problematic due to its very low fission yield, short half-life, and the complication of its gamma spectrum. At AWE, radiochemically purified 161Tb solution was ...measured on a PerkinElmer 1220 QuantulusTM Liquid Scintillation Spectrometer. Since there was no 161Tb certified standard solution available commercially, the counting efficiency was determined by the CIEMAT/NIST Efficiency Tracing method. The method was validated during a recent inter-laboratory comparison exercise involving the analysis of a uranium sample irradiated with thermal neutrons. The measured 161Tb result was in excellent agreement with the result using gamma spectrometry and the result obtained by Pacific Northwest National Laboratory.
•161Tb analysed by radiochemical separation and CNET LSC method.•BEGe detector also used for activity measurement and radio-purity verification.•Excellent agreement between results using CNET LSC, BEGe, and LEPS methods.•Lower uncertainty and better detection limit achieved by CNET LSC.
Fc gamma receptors (FcγRs) for IgG regulate adaptive immune responses by modulating activating and inhibitory signalling pathways within immune cells. Data from a haemophilia A mouse model ...demonstrate that genetic deletion or blockade of the inhibitory FcγR (CD32) suppresses the formation of antibody‐secreting cells (ASCs) in vitro. Mechanisms preventing the FVIII‐specific recall response, however, remain unclear. Here, the potential role of CD32 inhibition was studied by differentially modulating receptor activity with selected anti‐CD32 monoclonal antibodies (mAbs). Splenocytes from immunized FVIII‐/‐ mice were restimulated with FVIII in the absence or presence of different anti‐CD32 mAbs over 6 days. At day 6, cytokine release was quantified from cell culture supernatant and the formation of FVIII‐specific ASCs assessed. Binding of FVIII‐containing immune complexes (F8‐ICs) to bone marrow‐derived dendritic cells (BMdDCs) was also investigated. The antagonistic CD32 mAb AT128 suppressed the formation of FVIII‐specific ASCs and reduced secretion of IFN‐γ and IL‐10. In contrast, the agonistic mAbs AT130‐2 and AT130‐5, and their F(ab’)2 fragments, allowed the formation of FVIII‐specific ASCs, even though the full IgG of AT130‐2 reduced binding of F8‐ICs to CD32. Data suggest that an inhibitory signal is transmitted when F8‐ICs bind to CD32 and that this signal is required during memory B cell (MBC) activation to support formation of FVIII‐specific ASCs. If the inhibitory signal is lacking due to CD32 deletion or blockade with antagonistic anti‐CD32 mAbs, FVIII‐specific T cell stimulation and ASC formation are suppressed, whereas agonistic stimulation of CD32 restores T cell stimulation and ASC formation.
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