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  1. Free, publicly-accessible full text available August 9, 2024
  2. null (Ed.)
    Regioselectivity in colloidal self-assembly typically requires specific chemical interactions to guide particle binding. In this paper, we describe a new method to form selective colloidal bonds that relies solely on polymer adsorption. Mixtures of polymer-coated and bare particles are initially stable due to long-ranged electrostatic repulsion. When their charge is screened, the two species can approach each other close enough for polymer bridges to form, binding the particles together. By utilizing colloidal dumbbells, where each lobe is coated with polymer brushes of differing lengths, we demonstrate that the Debye screening length serves as a selective switch for the assembly of bare tracer particles onto the two lobes. We model the interaction using numerical self-consistent field lattice computations and show how regioselectivity arises from just a few nanometers difference in polymer brush length. 
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  3. Abstract

    While a stimulating effect of plant primary productivity on soil carbon dioxide (CO2) emissions has been well documented, links between gross primary productivity (GPP) and wetland methane (CH4) emissions are less well investigated. Determination of the influence of primary productivity on wetland CH4emissions (FCH4) is complicated by confounding influences of water table level and temperature on CH4production, which also vary seasonally. Here, we evaluate the link between preceding GPP and subsequent FCH4at two fens in Wisconsin using eddy covariance flux towers, Lost Creek (US‐Los) and Allequash Creek (US‐ALQ). Both wetlands are mosaics of forested and shrub wetlands, with US‐Los being larger in scale and having a more open canopy. Co‐located sites with multi‐year observations of flux, hydrology, and meteorology provide an opportunity to measure and compare lag effects on FCH4without interference due to differing climate. Daily average FCH4from US‐Los reached a maximum of 47.7 ηmol CH4m−2 s−1during the study period, while US‐ALQ was more than double at 117.9 ηmol CH4 m−2 s−1. The lagged influence of GPP on temperature‐normalized FCH4(Tair‐FCH4) was weaker and more delayed in a year with anomalously high precipitation than a following drier year at both sites. FCH4at US‐ALQ was lower coincident with higher stream discharge in the wet year (2019), potentially due to soil gas flushing during high precipitation events and lower water temperatures. Better understanding of the lagged influence of GPP on FCH4due to this study has implications for climate modeling and more accurate carbon budgeting.

     
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  4. Abstract

    The Large Hadron Collider at CERN will undergo an upgrade in order to increase its luminosity to 7.5 × 1034cm-2s-1. The increased luminosity during this High-Luminosity running phase, starting around 2029, means a higher rate of proton-proton interactions, hence a larger ionizing dose and particle fluence for the detectors. The current tracking system of the CMS experiment will be fully replaced in order to cope with the new operating conditions. Prototype planar pixel sensors for the CMS Inner Tracker with square 50 μm × 50 μm and rectangular 100 μm × 25 μm pixels read out by the RD53A chip were characterized in the lab and at the DESY-II testbeam facility in order to identify designs that meet the requirements of CMS during the High-Luminosity running phase. A spatial resolution of approximately 3.4 μm (2 μm) is obtained using the modules with 50 μm × 50 μm (100 μm × 25 μm) pixels at the optimal angle of incidence before irradiation. After irradiation to a 1 MeV neutron equivalent fluence of Φeq = 5.3 × 1015 cm-2, a resolution of 9.4 μm is achieved at a bias voltage of 800 V using a module with 50 μm × 50 μm pixel size. All modules retain a hit efficiency in excess of 99% after irradiation to fluences up to 2.1 × 1016 cm-2. Further studies of the electrical properties of the modules, especially crosstalk, are also presented in this paper.

     
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    Free, publicly-accessible full text available November 1, 2024
  5. Free, publicly-accessible full text available December 1, 2024
  6. Free, publicly-accessible full text available November 1, 2024
  7. Abstract

    A description is presented of the algorithms used to reconstruct energy deposited in the CMS hadron calorimeter during Run 2 (2015–2018) of the LHC. During Run 2, the characteristic bunch-crossing spacing for proton-proton collisions was 25 ns, which resulted in overlapping signals from adjacent crossings. The energy corresponding to a particular bunch crossing of interest is estimated using the known pulse shapes of energy depositions in the calorimeter, which are measured as functions of both energy and time. A variety of algorithms were developed to mitigate the effects of adjacent bunch crossings on local energy reconstruction in the hadron calorimeter in Run 2, and their performance is compared.

     
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    Free, publicly-accessible full text available November 1, 2024
  8. Free, publicly-accessible full text available November 1, 2024
  9. Free, publicly-accessible full text available November 1, 2024