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Competition between zwitterionic electrostatic forces and alkyl stabilization directs the stacking order of two-dimensional polymer sheets and resulting materials quality.

Molecular electronic spin qubits are promising candidates for quantum information science applications because they can be reliably produced and engineered via chemical design. Embedding electronic spin qubits within two-dimensional polymers (2DPs) offers the possibility to systematically engineer inter-qubit interactions while maintaining long coherence times, both of which are prerequisites to their technological utility. Here, we introduce electronic spin qubits into a diamagnetic 2DP by

Two-dimensional (2D) covalent organic frameworks (COFs) are composed of structurally precise, permanently porous, layered macromolecular sheets, which are traditionally synthesized as polycrystalline solids with crystalline domain lengths smaller than 100 nm. Here, we polymerize imine-linked 2D COFs as suspensions of faceted single crystals in as little as 5 min at moderate temperature and ambient pressure. Single crystals of two imine-linked 2D COFs were prepared, consisting of a rhombic 2D COF (

Characterizing the physical conditions (density, temperature, ionization state, metallicity, etc) of the interstellar medium is critical to our understanding of the formation and evolution of galaxies. Here we present a multi-line study of the interstellar medium in the host galaxy of a quasar at z~6.4, i.e., when the universe was 840 Myr old. This galaxy is one of the most active and massive objects emerging from the dark ages, and therefore represents a benchmark for models of the early formation of massive galaxies. We used the Atacama Large Millimeter Array to target an ensemble of tracers of ionized, neutral, and molecular gas, namely the fine-structure lines: [OIII] 88$\mu$m, [NII] 122$\mu$m, [CII] 158$\mu$m, and [CI] 370$\mu$m and the rotational transitions of CO(7-6), CO(15-14), CO(16-15), and CO(19-18); OH 163.1$\mu$m and 163.4$\mu$m; and H$_2$O 3(0,3)-2(1,2), 3(3,1)-4(0,4), 3(3,1)-3(2,2), 4(0,4)-3(1,3), 4(3,2)-4(2,3). All the targeted fine-structure lines are detected, as are half of the targeted molecular transitions. By combining the associated line luminosities, the constraints on the dust temperature from the underlying continuum emission, and predictions from photoionization models of the interstellar medium, we find that the ionized phase accounts for about one third of the total gaseous mass budget, and is responsible for half of the total [CII] emission. It is characterized by high density (n~180 cm$^{-3}$), typical of HII regions. The spectral energy distribution of the photoionizing radiation is comparable to that emitted by B-type stars. Star formation also appears to drive the excitation of the molecular medium. We find marginal evidence for outflow-related shocks in the dense molecular phase, but not in other gas phases. This study showcases the power of multi-line investigations in unveiling the properties of the star-forming medium in galaxies at cosmic dawn., Comment: 16 pages, 14 figures. Accepted for publication in A&A

Excitonic dynamics studies of a 2D COF, its corresponding hexagonal macrocycle, and extended nanotubes comprised of stacked macrocycles reveal that layering of the macrocycle in the assembled COF and nanotube lead to a prolonged exciton lifetime.

Synthetic chemists have developed robust methods to synthesize discrete molecules, linear and branched polymers, and disordered cross-linked networks. However, two-dimensional polymers (2DPs) prepared from designed monomers have been long missing from these capabilities, both as objects of chemical synthesis and in nature. Recently, new polymerization strategies and characterization methods have enabled the unambiguous realization of covalently linked macromolecular sheets. Here we review 2DPs and 2D polymerization methods. Three predominant 2D polymerization strategies have emerged to date, which produce 2DPs either as monolayers or multilayer assemblies. We discuss the fundamental understanding and scope of each of these approaches, including: the bond-forming reactions used, the synthetic diversity of 2DPs prepared, their multilayer stacking behaviors, nanoscale and mesoscale structures, and macroscale morphologies. Additionally, we describe the analytical tools currently available to characterize 2DPs in their various isolated forms. Finally, we review emergent 2DP properties and the potential applications of planar macromolecules. Throughout, we highlight achievements in 2D polymerization and identify opportunities for continued study.

Supramolecular polymers are compelling platforms for the design of stimuli-responsive materials with emergent functions. Here, we report the assembly of an amphiphilic nanotube for Li-ion conduction that exhibits high ionic conductivity, mechanical integrity, electrochemical stability, and solution processability. Imine condensation of a pyridine-containing diamine with a triethylene glycol functionalized isophthalaldehyde yields pore-functionalized macrocycles. Atomic force microscopy, scanning electron microscopy, and in solvo X-ray diffraction reveal that macrocycle protonation during their mild synthesis drives assembly into high-aspect ratio (>103) nanotubes with three interior triethylene glycol groups. Electrochemical impedance spectroscopy demonstrates that lithiated nanotubes are efficient Li+ conductors, with an activation energy of 0.42 eV and a peak room temperature conductivity of 3.91 ± 0.38 × 10-5 S cm-1. 7Li NMR and Raman spectroscopy show that lithiation occurs exclusively within the nanotube interior and implicates the glycol groups in facilitating efficient Li+ transduction. Linear sweep voltammetry and galvanostatic lithium plating-stripping tests reveal that this nanotube-based electrolyte is stable over a wide potential range and supports long-term cyclability. These findings demonstrate how the coupling of synthetic design and supramolecular structural control can yield high-performance ionic transporters that are amenable to device-relevant fabrication, as well as the technological potential of chemically designed self-assembled nanotubes.

We study Brightest Cluster Galaxies (BCGs) in $\sim5000$ galaxy clusters from the Hyper Suprime-Cam (HSC) Subaru Strategic Program. The sample is selected over an area of 830 $\textrm{deg}^2$ and is uniformly distributed in redshift over the range $z=0.3-1.0$. The clusters have stellar masses in the range $10^{11.8} - 10^{12.9} M_{\odot}$. We compare the stellar mass of the BCGs in each cluster to what we would expect if their masses were drawn from the mass distribution of the other member galaxies of the clusters. The BCGs are found to be "special", in the sense that they are not consistent with being a statistical extreme of the mass distribution of other cluster galaxies. This result is robust over the full range of cluster stellar masses and redshifts in the sample, indicating that BCGs are special up to a redshift of $z=1.0$. However, BCGs with a large separation from the center of the cluster are found to be consistent with being statistical extremes of the cluster member mass distribution. We discuss the implications of these findings for BCG formation scenarios., Comment: 14 pages, 12 figures. This is a pre-copyedited, author-produced PDF of an article accepted for publication in MNRAS following peer review. The version of record is available online at: https://doi.org/10.1093/mnras/stab2363

International audience; PFS (Prime Focus Spectrograph), a next generation facility instrument on the Subaru telescope, is now being tested on the telescope. The instrument is equipped with very wide (1.3 degrees in diameter) field of view on the Subaru's prime focus, high multiplexity by 2394 reconfigurable fibers, and wide waveband spectrograph that covers from 380nm to 1260nm simultaneously in one exposure. Currently engineering observations are ongoing with Prime Focus Instrument (PFI), Metrology Camera System (MCS), the first spectrpgraph module (SM1) with visible cameras and the first fiber cable providing optical link between PFI and SM1. Among the rest of the hardware, the second fiber cable has been already installed on the telescope and in the dome building since April 2022, and the two others were also delivered in June 2022. The integration and test of next SMs including near-infrared cameras are ongoing for timely deliveries. The progress in the software development is also worth noting. The instrument control software delivered with the subsystems is being well integrated with its system-level layer, the telescope system, observation planning software and associated databases. The data reduction pipelines are also rapidly progressing especially since sky spectra started being taken in early 2021 using Subaru Nigh Sky Spectrograph (SuNSS), and more recently using PFI during the engineering observations. In parallel to these instrumentation activities, the PFS science team in the collaboration is timely formulating a plan of large-sky survey observation to be proposed and conducted as a Subaru Strategic Program (SSP) from 2024. In this article, we report these recent progresses, ongoing developments and future perspectives of the PFS instrumentation.

Macrocycles that assemble into nanotubes exhibit emergent properties stemming from their low dimensionality, structural regularity, and distinct interior environments. We report a versatile strategy to synthesize diverse nanotube structures in a single, efficient reaction by using a conserved building block bearing a pyridine ring. Imine condensation of a 2,4,6-triphenylpyridine-based diamine with various aromatic dialdehydes yields chemically distinct pentagonal [5 + 5], hexagonal [3 + 3], and diamond-shaped [2 + 2] macrocycles depending on the substitution pattern of the aromatic dialdehyde monomer. Atomic force microscopy and in solvo X-ray diffraction demonstrate that protonation of the macrocycles under the mild conditions used for their synthesis drives assembly into high-aspect ratio nanotubes. Each of the pyridine-containing nanotube assemblies exhibited measurable proton conductivity by electrochemical impedance spectroscopy, with values as high as 10-3 S m-1 (90% R.H., 25 °C) that we attribute to differences in their internal pore sizes. This synthetic strategy represents a general method to access robust nanotube assemblies from a universal pyridine-containing monomer, which will enable systematic investigations of their emergent properties.

Dental enamel forms extracellularly as thin ribbons of amorphous calcium phosphate (ACP) that initiate on dentin mineral in close proximity to the ameloblast distal membrane. Secreted proteins are critical for this process. Enam−/− and Ambn−/− mice fail to form enamel. We characterize enamel ribbon formation in wild-type (WT), Amelx−/− and Mmp20−/− mouse mandibular incisors using focused ion beam scanning electron microscopy (FIB-SEM) in inverted backscatter mode. In Amelx−/− mice, initial enamel mineral ribbons extending from dentin are similar in form to those of WT mice. As early enamel development progresses, the Amelx−/− mineral ribbons develop multiple branches, resembling the staves of a Japanese fan. These striking fan-shaped structures cease growing after attaining ~ 20 µm of enamel thickness (WT is ~ 120 µm). The initial enamel mineral ribbons in Mmp20−/− mice, like those of the Amelx−/− and WT, extend from the dentin surface to the ameloblast membrane, but appear to be fewer in number and coated on their sides with organic material. Remarkably, Mmp20−/− mineral ribbons also form fan-like structures that extend to ~ 20 µm from the dentin surface. However, these fans are subsequently capped with a hard, disorganized outer mineral layer. Amelogenin cleavage products are the only matrix components absent in both Amelx−/− and Mmp20−/− mice. We conclude that MMP20 and amelogenin are not critical for enamel mineral ribbon initiation, orientation, or initial shape. The pathological fan-like plates in these mice may form from the lack of amelogenin cleavage products, which appear necessary to form ordered hydroxyapatite.

This case report describes an initially overlooked Type II decompression sickness (DCS) occurrence that was confused with a cerebral vascular accident in a patient with chronic atrial fibrillation (AF). The purpose of this case report is to reinforce the maxim that DCS needs to be suspected anytime a scuba diver experiences signs or symptoms compatible with DCS after completing a scuba dive.A 71-year-old scuba diver with a history of AF and who was taking warfarin made four dives, all with maximum depths less than 60 fsw (20 msw) over a 10-hour interval. Shoulder pain developed before entering the water on the fourth dive and was worse after exiting from the fourth dive. Twenty minutes later the diver collapsed while standing and was unable to make a grip using his left hand. A literature review failed to locate any case reports of divers with AF presenting with strokelike symptoms only to find the cause was Type II DCS..Initially the patient's findings were reviewed with a diving medicine team. The recommendation was for the patient to be managed for a stroke. The patient was transferred to a hospital for a computed tomography scan, but no recommendation was made for a hyperbaric oxygen recompression treatment. The scan showed no brain bleed or infarct. The attending neurologist (not diving medicine-trained) was concerned that the patient's findings were diving-related and arranged for transferring the patient to a hyperbaric medicine facility 25 hours later. With hyperbaric oxygen (HBO2) therapy the patient's symptoms remitted over several weeks.The presence of symptoms attributed to a stroke immediately after a scuba dive should not deter a trial of HBO2 therapy. The delay in starting HBO2 therapy is concerning and perhaps the reason recovery was delayed and the need for repetitive HBO2 therapies.

Acute traumatic ischemias are an array of disorders that range from crush injuries to compartment syndromes, from burns to frostbite and from threatened flaps to compromised reimplantations. Two unifying components common to these conditions are a history of trauma be it physical, thermal, or surgical coupled with ischemia to the traumatized tissues. Their pathophysiology resolves around the self-perpetuating cycle of edema and ischemia, and their severity represents a spectrum from mild, almost non-existent, to tissue death. Since ischemia is a fundamental component of the traumatic ischemias and hypoxia is a consequence of ischemia, hyperbaric oxygen is a logical intervention for those conditions where tissue survival, infection control and healing is at risk. Unfortunately, even with mechanisms of hyperbaric oxygen that strongly support its usefulness in traumatic ischemias coupled with supportive clinical data, clinicians are disinclined to utilize it for these conditions. This focuses on the orthopedic aspects of the traumatic ischemias, namely crush injury and compartment syndrome, and show how hyperbaric oxygen treatments can mitigate their severity.

Two-dimensional covalent organic frameworks (2D COFs) are layered, structurally regular, and permanently porous macromolecules. When reactive groups are embedded into a COF structure, subsequent chemical reactions can be performed following polymerization. As such, a postsynthetic modification (PSM) strategy provides diverse materials from a single set of COF monomers and polymerization protocols. Here, we report the synthesis of an asymmetric dibenzocyclooctyne-containing imine-linked 2D COF, which readily undergoes strain-promoted azide-alkyne cycloaddition (SPAAC) reactions without catalyst under mild and dilute conditions. This approach was used to quantitatively decorate the COF lattice with alkyl chains and amines, all without the need for exogenous species. Functionalization may result in spontaneous delamination of bulk COF materials into solution-stable sheets, demonstrating the utility of this technique. As such, this platform is useful for postsynthetic functionalization with sensitive chemical functionalities that are not amenable to direct polymerization or existing PSM strategies.

The recognition of states is a critical feature of international law, defining the actors that are subject to it and conferring rights and duties related to their interactions with other states. This recognition is traditionally based on criteria that are deemed essential for a state to exist, even if political factors often play a role. In recent years, it has become apparent that state recognition and de-recognition is sometimes linked to the recognising state’s future access to natural resources found on the territory of the state whose sovereignty is being recognised there. Although this phenomenon is not openly stated, the evidence is circumstantial but abundant, and Africa is at the centre of it. This makes the continent a laboratory for the practice and its consequences, not only for the states involved but also for the broader recognition process. This phenomenon seems to be occurring in two ways. The first way in which this happens is when states use their capacity to produce natural resources that other states need in order to obtain concessions from those states in the form of recognitions of sovereignty over the territory involved. An example is Morocco and its enormous phosphate reserves: various African states that need phosphate for food production have de-recognised the Sahrawi Arab Democratic Republic as an independent state, while recognising Moroccan sovereignty over the same territory – the former Spanish Sahara. The other way in which this happens is illustrated by China’s investments in numerous African countries. The exploitation of natural resources that can be exported to China has been the primary motive for such investments. Some African states that have sought to attract investments have derecognised Taiwan and have recognised China’s sovereignty over the island. This paper describes and assesses the apparent links between African natural resources and the forces that influence state recognition, with a view to identifying the consequences for Africa and for states around the world more generally. La reconnaissance des États est une caractéristique essentielle du droit international ; définir les acteurs qui y sont soumis et leur conférer des droits et obligations liés à leurs interactions avec d’autres États. Cette reconnaissance est traditionnellement basée sur des critères jugés essentiels à l’existence d’un État, même si parfois les facteurs politiques jouent un rôle. Ces dernières années, il est devenu évident que la reconnaissance et le désaveu d’un État sont parfois liés à l’accès futur de l’État reconnu aux ressources naturelles trouvées sur le territoire de l’État dont la souveraineté y est reconnue. Bien que ce phénomène n’est pas clairement/ouvertement déclaré, la preuve est circonstancielle mais abondante, et l’Afrique en est le centre. Cela fait du continent un laboratoire pour la pratique et ses conséquences, non seulement pour les États concernés mais aussi en général pour le processus de reconnaissance. Ce phénomène semble se produire de deux façons. La première façon dont cela se produit est lorsque les États utilisent leur capacité à produire lesº ressources naturelles dont d’autres ont besoin enfin d’obtenir des concessions de ces États sous la forme de la reconnaissance de souveraineté sur le territoire concerné. Le Maroc avec ses énormes réserves de phosphate en est un exemple : divers États africains qui ont besoin de phosphate pour la production alimentaire ont désavoué la République arabe sahraouie démocratique comme un État indépendant tout en reconnaissant la souveraineté marocaine sur le même territoire – l’ancien Sahara espagnol. L’autre manière dont cela se produit est illustrée par l’investissement chinois dans beaucoup de pays africains. Cette exploitation des ressources naturelles que la Chine peux exporter est le principal motif de ces investissements, car certains États africains qui cherchent à attirer les investissements ont désavoué Taiwan et ont reconnu la souveraineté de la Chine sur le l’île. Cette article décrit et analyse les liens apparents entre les ressources naturelles africaines et les forces qui influencent la reconnaissance de l’État, dans un but d’identifier les conséquences pour l’Afrique et les États du monde en général.

A longstanding question when studying Brightest Cluster Galaxies (BCGs) and their evolution is whether their luminosities are statistical extremes of the luminosity distribution of other cluster member galaxies, or whether their luminosities follow a different,“special” distribution. To explore this question, we use the two Tremaine–Richstone (TR) statistics that sometimes lead to different conclusions about BCG specialness. We run Monte Carlo simulations of galaxy clusters with varying galaxy luminosity functions and BCG properties, and explore the sensitivity of the TR statistics to the adjusted BCG properties. We identify cases where the two statistics lead to different conclusions. The first of the TR statistics, which relies on the spread of BCG luminosities, is more reliable for determining specialness than the second, which utilizes the spread in the luminosity gap between the BCG and second ranked galaxy.

A more robust mechanistic understanding of imine-linked two-dimensional covalent organic frameworks (2D COFs) is needed to improve their crystalline domain sizes and to control their morphology, both of which are necessary to fully realize their application potential. Here, we present evidence that 2D imine-linked COFs rapidly polymerize as crystalline sheets that subsequently reorganize to form stacked structures. Primarily, this study focuses on the first few minutes of 1,3,5-tris(4-aminophenyl)benzene and terephthaldehyde polymerization, which yields an imine-linked 2D COF. In situ X-ray diffraction and thorough characterization of solids obtained using gentler isolation and activation methods than have typically been used in the literature indicate that periodic imine-linked 2D structures form within 60 s, which then form more ordered stacked structures over the course of several hours. This stacking process imparts improved stability toward the isolation process relative to that of the early stage materials, which likely obfuscated previous mechanistic conclusions regarding 2D polymerization that were based on products isolated using harsh activation methods. This revised mechanistic picture has useful implications; the 2D COF layers isolated at very short reaction times are easily exfoliated, as observed in this work using high-resolution transmission electron microscopy and atomic force microscopy. These results suggest improved control of imine-linked 2D COF formation can be obtained through manipulation of the polymerization conditions and interlayer interactions. Qualitatively similar results were obtained for analogous materials obtained from 2,5-di(alkoxy)terephthaldehyde derivatives, except for the COF with the longest alkoxy chains examined (OC12H25), which, although shown by in situ X-ray diffraction to be highly crystalline in the reaction mixture, is much less crystalline when isolated than the other COFs examined, likely due to the more severe steric impact of the dodecyloxy functionality on the stacking process.

We present ALMA sub-kpc- to kpc-scale resolution observations of the [CII], CO(9-8), and OH$^{+}$\,($1_{1}$--$0_{1}$) lines along with their dust continuum emission toward the FIR luminous quasar SDSS J231038.88+185519.7 at $z = 6.0031$. The [CII] brightness follows a flat distribution with a Sersic index of 0.59. The CO(9-8) line and the dust continuum can be fit with an unresolved nuclear component and an extended Sersic component with a Sersic index of ~1. The dust temperature drops with distance from the center. The effective radius of the dust continuum is smaller than that of the line emission and the dust mass surface density, but is consistent with that of the star formation rate surface density. The OH$^{+}$\,($1_{1}$--$0_{1}$) line shows a P-Cygni profile with an absorption, which may indicate an outflow with a neutral gas mass of $(6.2\pm1.2)\times10^{8} M_{\odot}$ along the line of sight. We employed a 3D tilted ring model to fit the [CII] and CO(9-8) data cubes. The two lines are both rotation dominated and trace identical disk geometries and gas motions. We decompose the circular rotation curve measured from the kinematic model fit to the [CII] line into four matter components (black hole, stars, gas, and dark matter). The quasar-starburst system is dominated by baryonic matter inside the central few kiloparsecs. We constrain the black hole mass to be $2.97^{+0.51}_{-0.77}\times 10^{9}\,M_{\odot}$; this is the first time that the dynamical mass of a black hole has been measured at $z\sim6$. A massive stellar component (on the order of $10^{9}\,M_{\odot}$) may have already existed when the Universe was only ~0.93 Gyr old. The relations between the black hole mass and the baryonic mass of this quasar indicate that the central supermassive black hole may have formed before its host galaxy. [Abridged version. Please see the full abstract in the manuscript.], Comment: Accepted for publication in A&A