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Abstract: Biochar is a carbon-rich product generated from biomass through pyrolysis. This study evaluated the ability of an unmodified biochar to sorb two triazine pesticides – atrazine and simazine, and thereby explored potential environmental values of biochar on mitigating pesticide pollution in agricultural production and removing contaminants from wastewater. A greenwaste biochar was produced by heating waste biomass under the oxygen-limited condition at 450°C. The effects of several experimental parameters, including biochar particle size, contact time, solid/solution ratio, and solution pH on the sorption of atrazine and simazine were comprehensively investigated. The biochar with small particle size needed less time to reach sorption equilibrium. The sorption affinity of the biochar for the two pesticides increased with decreasing solid/solution ratio. The sorbed amounts (C s) of atrazine and simazine increased from 451 to 1158mg/kg and 243 to 1066mg/kg, respectively, when the solid/solution ratio decreased from 1:50 to 1:1000 (g/mL). The sorption of the biochar for both pesticides was favored by low pH. The sorption isotherms of atrazine and simazine on the biochar are nonlinear and follow a Freundlich model. When atrazine and simazine co-existed, a competitive sorption occurred between these two pesticides on the biochar, reflecting a decrease in sorption capacity (K f) from 435 to 286 for atrazine and from 514 to 212 for simazine. Combined adsorption and partition mechanisms well depicted sorption of atrazine and simazine on carbonized and noncarbonized fractions of the biochar in the single-solute and co-solute systems. [Copyright &y& Elsevier]

Gamma-ray spectrometry systems based on High-Purity Germanium (HPGe) have been the long-standing leader in terms of resolution since their introduction many years ago. The application of this technology to the spectroscopic assay of special nuclear material led to the development of several isotopic analysis tools, including the advanced software package FRAM, which was, and continues to be, developed at Los Alamos National Laboratory. Although FRAM can be applied over a wide range of energies, the significantly higher intensity of the x-ray region in the neighborhood of 100 keV makes analysis of this area of the spectrum advantageous, especially in the case of plutonium. However, even with HPGe, the multitude of gamma-ray and x-ray peaks that exist in the 100-keV region are sufficiently convoluted so as to preclude determination of plutonium isotopic composition without the introduction of some error. The novel technology of cryogenic microcalorimeter detectors, shown to have an order of magnitude better spectral resolution than HPGe, has recently opened new doors with respect to these difficulties. Now, for the first time, the powerful capabilities of FRAM have been paired with the unparalleled resolution of microcalorimetry in the analysis of plutonium spectra. Preliminary results of these analyses, as well as an outlook for future measurements, heretofore unobtainable with HPGe, will be presented. [ABSTRACT FROM AUTHOR]

We discuss sensor and method development for the analysis of alpha- and beta-decaying radioisotopes encapsulatedwithin superconducting transition-edge sensor microcalorimeter absorbers. For alpha-decaying isotopes, e.g., ^238\Pu, ^241\Am, and ^210\Po, this is a measurement of the total nuclearreaction energy (Q) and the spectra consist of sharp, narrow peaks. The primary peak is at the Q value, with secondarypeaks corresponding to gamma-ray-escape peaks. In contrast, for beta-decaying isotopes, e.g., ^241\Pu, the spectrum is a low-energy continuum ending at E\!=\!Q. We are developing transition-edge-sensor(TES) microcalorimeters to measure these spectra simultaneously in a single sample, hence allowing quantitative analysisof all Pu isotopes from 238 to 242. We have developed and used TES microcalorimeter detectors for this purpose, and itrepresents a new quantitative analysis tool for nuclear forensics and safeguards. Due to the high efficiency of theembedded source geometry, measurement times can be minimized. The high dynamic range of our sensors creates theopportunity to measure the relatively low energy beta-decay spectrum of ^241\Pu\ (Q = 20.78\ \keV) simultaneouslywith the Q $\sim$ 5–6 MeV of alpha-decaying actinides. Finally, thetechnique could also be effective for determining the time since chemical purification of Pu using the ^241\Pu/^241\Am isotopic ratio via simultaneousmeasurement of the low-energy ^241\Pu beta particles and the high-energy ^241\Am Q-value. [ABSTRACT FROM PUBLISHER]

Single-photon detectors based on the superconducting transition-edge sensor are used in a number of visible to near-infrared applications, particularly for photon-number-resolving measurements in quantum information science. To be practical for large-scale spectroscopic imaging or photonic quantum computing applications, the size of visible to near-infrared transition-edge sensor arrays and their associated readouts must be increased from a few pixels to many thousands. In this manuscript, we introduce the kinetic inductance current sensor, a scalable readout technology that exploits the nonlinear kinetic inductance in a superconducting resonator to make sensitive current measurements. Kinetic inductance current sensors can replace superconducting quantum interference devices for many applications because of their ability to measure fast, high slew-rate signals, their compatibility with standard microwave frequency-division multiplexing techniques, and their relatively simple fabrication. Here, we demonstrate the readout of a visible to near-infrared transition-edge sensor using a kinetic inductance current sensor with 3.7 MHz of bandwidth. We measure a readout noise of 1.4 pA / Hz , considerably below the detector noise at frequencies of interest, and an energy resolution of (0.137 ± 0.001) eV at 0.8 eV, comparable to resolutions observed with non-multiplexed superconducting quantum interference device readouts., (© 2024. The Author(s).)

Feature sizes in integrated circuits have decreased substantially over time, and it has become increasingly difficult to three-dimensionally image these complex circuits after fabrication. This can be important for process development, defect analysis, and detection of unexpected structures in externally sourced chips, among other applications. Here, we report on a non-destructive, tabletop approach that addresses this imaging problem through x-ray tomography, which we uniquely realize with an instrument that combines a scanning electron microscope (SEM) with a transition-edge sensor (TES) x-ray spectrometer. Our approach uses the highly focused SEM electron beam to generate a small x-ray generation region in a carefully designed target layer that is placed over the sample being tested. With the high collection efficiency and resolving power of a TES spectrometer, we can isolate x-rays generated in the target from background and trace their paths through regions of interest in the sample layers, providing information about the various materials along the x-ray paths through their attenuation functions. We have recently demonstrated our approach using a 240 Mo/Cu bilayer TES prototype instrument on a simplified test sample containing features with sizes of ∼ 1 μ m. Currently, we are designing and building a 3000 Mo/Au bilayer TES spectrometer upgrade, which is expected to improve the imaging speed by factor of up to 60 through a combination of increased detector number and detector speed.