catena-Poly[[[tetra­aqua­zinc(II)]-μ-4,4′-bipyridine-κ2 N:N′] naphthalene-1,5-disulfonate]

In the title complex, {[Zn(C10H8N2)(H2O)4](C10H6O6S2)}n, the [Zn(4,4′-bipy)(H2O)4]2+ (4,4′-bipy is 4,4′-bipyridine) cations are linked into linear chains along [001] by the 4,4′-bipy ligands. The ZnII ion exhibits a slightly distorted octa­hedral coordination geometry in which the four water mol­ecules are in the equatorial positions. The anions are hydrogen bonded to the polycationic chains by O—H⋯O hydrogen bonds, forming a three-dimensional network. The ZnII ion, 4,4′-bipy ligand and anion lie on special positions of 2/m site symmetry

(Z)-1,3,4a-Trimethyl-5,5-diphenyl-6-oxa-1,3-diaza­bicyclo­[4.2.0]octane-2,4-dione

The title compound, C20H20N2O3, is a head-to-tail oxetane, one of the regioisomers obtained by the the Paternó–Büchi reaction of 1,3-dimethyl­thymine with benzophenone. The oxetane ring is folded, the dihedral angle between the C—O—C and C—C—C planes being 14.4 (2)°. The dihedral angle between the two phenyl rings is 64.3 (2)°. The pyrimidine ring adopts a boat conformation. The crystal structure involves weak C—H⋯O hydrogen bonds

Neural Circuits and Some New Factors Involved in Hippocampal Memory

Humans and other primates have memory, and the hippocampus plays a critical role in this process. The neural circuitry is one of the structural foundations for the hippocampus in exerting memory function. To understand the relationship between the hippocampus and memory, we need to understand neural circuits. Past research has identified several classical neural circuits involved in memory. Although there are challenges with the study of hippocampal neural circuits, research on this topic has continued, and some progress has been made. Here, we discuss recent advances in our understanding of hippocampal neural circuit mechanisms and some of the newly discovered factors that affect memory. Substantial progress has been made regarding hippocampal memory circuits and Alzheimer’s disease. However, it is unclear whether these novel findings regarding hippocampal memory circuits hold promise for human memory studies. Additional research on this topic is needed

catena-Poly[[dichloridozinc(II)]-μ-[1,1′-(butane-1,4-di­yl)diimidazole-κ2 N 3:N 3′]]

The title one-dimensional coordination polymer, [ZnCl2(C10H14N4)]n, was synthesized by hydro­thermal methods from ZnCl2 and 1,1′-(butane-1,4-di­yl)diimidazole. The Zn atom is coordinated by two chloride ions and two N atoms from two symmetry-independent organic ligands and shows a distorted tetra­hedral coordination geometry. The 1,1′-(butane-1,4-di­yl)diimidazole ligands are located around two sets of inversion centers and bridge ZnII ions, forming a zigzag polymeric chain. C—H⋯Cl hydrogen bonding results in the formation of a three-dimensional supra­molecular networ

Testing the ALP-photon coupling with polarization measurements of Sagittarius A*

Ultra-light bosons such as axions or axion-like particles (ALPs), are promising candidates to solve the dark matter problem. A unique way to detect such ALPs is to search for the periodic oscillation feature of the position angles of linearly polarized photons emitted from the regions where ALP dark matter forms a solitonic core. In this work, we use the high-resolution polarimetric measurements of the radiation near the super-massive black hole (SMBH) in the center of the Milky Way, i.e., Sagittarius A$^\star$ (Sgr A$^\star$), by a sub-array of the Event Horizon Telescope to search for the ultra-light ALPs. We derive upper limits on the ALP-photon coupling of $\sim 10^{-12}{\rm GeV^{-1}}$ for ALP masses of $m\sim (10^{-19}-10^{-18})$eV. Our results are stronger than that derived from the observations of SN1987A and a population of supernovae in the mass window of ($10^{-19}-10^{-17}$)eV. Improved polarimetric measurements with the full Event Horizon Telescope can further strengthen the constraints.Comment: Accepted for publication in JCAP. 13 pages, 2 figure