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1. The LLV Algebra for Primitive Symplectic Varieties with Isolated Singularities

   https://doi.org/10.46298/epiga.2025.12186  

   Tighe, Benjamin (March 2025, Épijournal de Géométrie Algébrique)

   We extend results of Looijenga--Lunts and Verbitsky and show that the total Lie algebra $$\mathfrak g$$ for the intersection cohomology of a primitive symplectic variety $$X$$ with isolated singularities is isomorphic to $$\mathfrak g \cong \mathfrak{so}\left(\left(IH^2(X, \mathbb Q), Q_X\right)\oplus \mathfrak h\right),$$ where $$Q_X$$ is the intersection Beauville--Bogomolov--Fujiki form and $$\mathfrak h$$ is a hyperbolic plane. This gives a new, algebraic proof for irreducible holomorphic symplectic manifolds which does not rely on the hyperk\"ahler metric. Along the way, we study the structure of $$IH^*(X, \mathbb Q)$$ as a $$\mathfrak{g}$$-representation -- with particular emphasis on the Verbitsky component, multidimensional Kuga--Satake constructions, and Mumford--Tate algebras -- and give some immediate applications concerning the $P = W$ conjecture for primitive symplectic varieties. Comment: 41 pages; Final journal version; new subsection on LLV algebra for symplectic orbifolds 

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2. Application of Aqueous-Based Covalent Crosslinking Strategies to the Formation of Metal Chalcogenide Gels and Aerogels

   https://doi.org/zpch-2018-1171  

   Hewavitharana, Indika K.; Brock, Stephanie L. (April 2018, Zeitschrift für physikalische Chemie)

   An aqueous-based metal ion crosslinking approach for assembly of metal chalcogenide nanoparticles (NPs) into robust gels is reported. Short chalcogenide ligands (S2−) undergo crosslinking with metal salts (Sn4+) to form a gel [NP/S2−/Sn4+]n (NP = PbTe, PbS, CdS, CdSe). The corresponding aerogel networks retain the crystallinity and quantum confinement effects of the native building blocks while achieving excellent porosity [Brunauer–Emmett–Teller (BET) surface areas of 160–238 m2/g]. Treatment of sulfide-capped PbTe nanoparticles with an excess of Sn4+ leads to ion exchange and formation of an amorphous “SnTe” gel. 

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3. The stormy life of galaxy clusters

   https://doi.org/10.1063/PT.3.4112  

   Rudnick, Lawrence (January 2019, Physics Today)

   Galaxy clusters form from the infall of dark and baryonic matter at the intersection of cosmic filaments. Most of the baryons are in the form of a hot, magnetized, intracluster plasma detected through its X-ray thermal bremsstrahlung emission. This plasma is tightly coupled to a second, cosmic ray plasma, detected through its synchrotron radio emission. Together, the properties of these plasmas encode the history of the cluster's formation and provide a snapshot of the ongoing cluster evolution. This article provides an overview for the more general astrophysical and space plasma community of the dynamical processes revealed by the diffuse plasma emissions. 

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4. Layered NaBa2M3Q3(Q2) (M = Cu, Ag; Q = S, Se) Chalcogenides and Local Ordering in Their Mixed-Anion Compositions

   Tassanov, Ayat; Lee, Huiju; Xia, Yi; Hodges, James M (August 2024, Inorganic chemistry)

   Three new NaBa2M3Q3(Q2) (M = Ag, Cu; Q = S, Se) chalcogenides were prepared using solid-state methods and structurally characterized using single-crystal X-ray diffraction. NaBa2Ag3Se3(Se2) and NaBa2Cu3Se3(Se2) crystallize in the monoclinic C2/m space group and have a two-dimensional structure composed of edge-sharing MSe4/4 tetrahedra separated by Na+ and Ba2+ cations, along with (Se2)2- dimers at the center of the spacings between [M3Se3]3- slabs. NaBa2Ag3S3(S2) adopts a related structure with the C2/m space group but has additional, crystallographically distinct Ag atoms in the [Ag3S3]3- layer that are linearly coordinated. NaBa2Ag3Se3(Se2) and NaBa2Ag3S3(S2) have indirect band gaps measured to be 1.2 eV and 1.9 eV, respectively, which is supported by band structures calculated using density functional theory. Mixed- anion NaBa2Cu3Se5-xSx compositions were prepared to probe for the presence of anion ordering and heteronuclear (S-Se)2- dimers. Structural analyses of the sulfoselenides indicate selenium preferentially occupies the Q-Q dimer sites, while Raman spectroscopy reveals a mixture of (S2), (Se2), and heteronuclear (S-Se) units in the sulfur-rich products. The local ordering of the chalcogens is rationalized using simple bonding concepts and adds to a growing framework for understanding ordering phenomena in mixed-anion systems. 

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5. Structure and inhibition of SARS-CoV-2 spike refolding in membranes

   https://doi.org/10.1126/science.adn5658  

   Grunst, Michael W; Qin, Zhuan; Dodero-Rojas, Esteban; Ding, Shilei; Prévost, Jérémie; Chen, Yaozong; Hu, Yanping; Pazgier, Marzena; Wu, Shenping; Xie, Xuping; et al (August 2024, Science)

   The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein binds the receptor angiotensin converting enzyme 2 (ACE2) and drives virus-host membrane fusion through refolding of its S2 domain. Whereas the S1 domain contains high sequence variability, the S2 domain is conserved and is a promising pan-betacoronavirus vaccine target. We applied cryo–electron tomography to capture intermediates of S2 refolding and understand inhibition by antibodies to the S2 stem-helix. Subtomogram averaging revealed ACE2 dimers cross-linking spikes before transitioning into S2 intermediates, which were captured at various stages of refolding. Pan-betacoronavirus neutralizing antibodies targeting the S2 stem-helix bound to and inhibited refolding of spike prehairpin intermediates. Combined with molecular dynamics simulations, these structures elucidate the process of SARS-CoV-2 entry and reveal how pan-betacoronavirus S2-targeting antibodies neutralize infectivity by arresting prehairpin intermediates. 

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