An official website of the United States government
Abstract The Poisson–Boltzmann (PB) model is a widely used electrostatic model for biomolecular solvation analysis. Formulated as an elliptic interface problem, the PB model can be numerically solved on either Eulerian meshes using finite difference/finite element methods or Lagrangian meshes using boundary element methods. Molecular surface generators, which produce the discretized dielectric interfaces between solutes and solvents, are critical factors in determining the accuracy and efficiency of the PB solvers. In this work, we investigate the utility of the Eulerian Solvent Excluded Surface (ESES) software for rendering conjugated Eulerian and Lagrangian surface representations, which enables us to numerically validate and compare the quality of Eulerian PB solvers, such as the MIBPB solver, and the Lagrangian PB solvers, such as the TABI‐PB solver. Furthermore, with the ESES software and its associated PB solvers, we are able to numerically validate an interesting and useful but often neglected source‐target symmetric property associated with the linearized PB model.
more »
« less
This content will become publicly available on April 16, 2026
A global review of long-range transported lead concentration and isotopic ratio records in snow and ice
Lead (Pb) has been used in human civilization for centuries, but the quantity and source of Pb pollution released into the environment varies spatially and temporally. Ice cores and snowpits are an excellent record of past Pb use.
more »
« less
- PAR ID:
- 10653666
- Publisher / Repository:
- Environmental Science: Processes and Impacts, Royal Society of Chemistry
- Date Published:
- Journal Name:
- Environmental Science: Processes & Impacts
- Volume:
- 27
- Issue:
- 4
- ISSN:
- 2050-7887
- Page Range / eLocation ID:
- 878 to 891
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
A<sc>bstract</sc> The azimuthal anisotropy of particles associated with jets (jet particles) at midrapidity is measured for the first time in p-Pb and Pb-Pb collisions at$$ \sqrt{{\textrm{s}}_{\textrm{NN}}} $$ = 5.02 TeV down to transverse momentum (pT) of 0.5 GeV/cand 2 GeV/c, respectively, with ALICE. The results obtained in p-Pb collisions are based on a novel three-particle correlation technique. The azimuthal anisotropy coefficientv2in high-multiplicity p-Pb collisions is positive, with a significance reaching 6.8σat lowpT, and its magnitude is smaller than in semicentral Pb-Pb collisions. In contrast to the measurements in Pb-Pb collisions, thev2coefficient is also found independent ofpTwithin uncertainties. Comparisons with the inclusive charged-particlev2and with AMPT calculations are discussed. The predictions suggest that parton interactions play an important role in generating a non-zero jet-particlev2in p-Pb collisions, even though they overestimate the reported measurement. These observations shed new insights on the understanding of the origin of the collective behaviour of jet particles in small systems such as p-Pb collisions, and provide significant stringent new constraints to models.more » « less
-
Goodkin, Nathalie (Ed.)Abstract Most oceanic lead (Pb) is from anthropogenic emissions into the atmosphere deposited into surface waters, mostly during the past two centuries. The space‐ and time‐dependent emission patterns of anthropogenic Pb (and its isotope ratios) constitute a global geochemical experiment providing information on advective, mixing, chemical, and particle flux processes redistributing Pb within the ocean. Pb shares aspects of its behavior with other elements, for example, atmospheric input, dust solubilization, biological uptake, and reversible exchange between dissolved and adsorbed Pb on sinking particles. The evolving distributions allow us to see signals hidden in steady‐state tracer distributions. The global anthropogenic Pb emission experiment serves as a tool to understand oceanic trace element dynamics. We obtained a high‐resolution (5° station spacing) depth transect of dissolved Pb concentrations and Pb isotopes from Alaska (55°N) to just north of Tahiti (20°S) near 152°W longitude. The sections reveal distinct sources of Pb (American, Australian, and Chinese), transport of Australian style Pb to the water mass formation region of Sub‐Antarctic Mode Water which is advected northward, columnar Pb isotope contours due to reversible particle exchange on sinking particles from high‐productivity particle veils, and a gradient of high northern deep water [Pb] to low southern deep water [Pb] that is created by reversible exchange release of Pb from sinking particles carrying predominantly northern hemisphere Pb.208Pb/206Pb versus206Pb/207Pb isotope relationships show that most oceanic Pb in the North Pacific is from Chinese and American sources, whereas Pb in the South Pacific is from Australian and American sources.more » « less
-
A bstract The production of the W ± bosons measured in p–Pb collisions at a centre-of-mass energy per nucleon–nucleon collision $$ \sqrt{s_{\textrm{NN}}} $$ s NN = 8 . 16 TeV and Pb–Pb collisions at $$ \sqrt{s_{\textrm{NN}}} $$ s NN = 5 . 02 TeV with ALICE at the LHC is presented. The W ± bosons are measured via their muonic decay channel, with the muon reconstructed in the pseudorapidity region − 4 < $$ {\eta}_{\textrm{lab}}^{\mu } $$ η lab μ < − 2 . 5 with transverse momentum $$ {p}_{\textrm{T}}^{\mu } $$ p T μ > 10 GeV /c . While in Pb–Pb collisions the measurements are performed in the forward (2 . 5 < $$ {y}_{\textrm{cms}}^{\mu } $$ y cms μ < 4) rapidity region, in p–Pb collisions, where the centre-of-mass frame is boosted with respect to the laboratory frame, the measurements are performed in the backward ( − 4 . 46 < $$ {y}_{\textrm{cms}}^{\mu } $$ y cms μ < − 2 . 96) and forward (2 . 03 < $$ {y}_{\textrm{cms}}^{\mu } $$ y cms μ < 3 . 53) rapidity regions. The W − and W + production cross sections, lepton-charge asymmetry, and nuclear modification factors are evaluated as a function of the muon rapidity. In order to study the production as a function of the p–Pb collision centrality, the production cross sections of the W − and W + bosons are combined and normalised to the average number of binary nucleon–nucleon collision 〈 N coll 〉. In Pb–Pb collisions, the same measurements are presented as a function of the collision centrality. Study of the binary scaling of the W ± -boson cross sections in p–Pb and Pb–Pb collisions is also reported. The results are compared with perturbative QCD calculations, with and without nuclear modifications of the Parton Distribution Functions (PDFs), as well as with available data at the LHC. Significant deviations from the theory expectations are found in the two collision systems, indicating that the measurements can provide additional constraints for the determination of nuclear PDFs and in particular of the light-quark distributions.more » « less
-
Abstract Despite its electron deficiency, boron can form multiple bonds with a variety of elements. However, multiple bonds between boron and main-group metal elements are relatively rare. Here we report the observation of boron-lead multiple bonds in PbB2O–and PbB3O2–, which are produced and characterized in a cluster beam. PbB2O–is found to have an open-shell linear structure, in which the bond order of B☱Pb is 2.5, while the closed-shell [Pb≡B–B≡O]2–contains a B≡Pb triple bond. PbB3O2–is shown to have a Y-shaped structure with a terminal B = Pb double bond coordinated by two boronyl ligands. Comparison between [Pb≡B–B≡O]2–/[Pb=B(B≡O)2]–and the isoelectronic [Pb≡B–C≡O]–/[Pb=B(C≡O)2]+carbonyl counterparts further reveals transition-metal-like behaviors for the central B atoms. Additional theoretical studies show that Ge and Sn can form similar boron species as Pb, suggesting the possibilities to synthesize new compounds containing multiple boron bonds with heavy group-14 elements.more » « less
