Spin Crossover and Fluorine-Specific Interactions in Metal Complexes of Terpyridines with Polyfluorocarbon Tails

In coordination chemistry and materials science, terpyridine ligands are of great interest, due to their ability to form stable complexes with a broad range of transition metal ions. We report three terpyridine ligands containing different perfluorocarbon (PFC) tails on the backbone and the corresponding FeII and CoII complexes. The CoII complexes display spin crossover close to ambient temperature, and the nature of this spin transition is influenced by the length of the PFC tail on the ligand backbone. The electrochemical properties of the metal complexes were investigated with cyclic voltammetry revealing one oxidation and several reduction processes. The fluorine-specific interactions were investigated by EPR measurements. Analysis of the EPR spectra of the complexes as microcrystalline powders and in solution reveals exchange-narrowed spectra without resolved hyperfine splittings arising from the 59Co nucleus; this suggests complex aggregation in solution mediated by interactions of the PFC tails. Interestingly, addition of perfluoro-octanol in different ratios to the acetonitrile solution of the sample resulted in the disruption of the F... F interactions of the tails. To the best of our knowledge, this is the first investigation of fluorine-specific interactions in metal complexes through EPR spectroscopy, as exemplified by exchange narrowing

CI and CO in Nearby Spiral Galaxies -- I. Line Ratio and Abundance Variations at ~ 200 pc Scales

We present new neutral atomic carbon [CI](3P1-3P0) mapping observations within the inner ~7 kpc and ~4 kpc of the disks of NGC3627 and NGC4321 at a spatial resolution of 190 pc and 270 pc, respectively, using the ALMA Atacama Compact Array (ACA). We combine these with the CO(2-1) data from PHANGS-ALMA, and literature [CI] and CO data for two other starburst and/or active galactic nucleus (AGN) galaxies (NGC1808, NGC7469), to study: a) the spatial distributions of CI and CO emission; b) the observed line ratio RCICO = I_[CI](1-0)/I_CO(2-1) as a function of various galactic properties; and c) the abundance ratio of [CI/CO]. We find excellent spatial correspondence between CI and CO emission and nearly uniform RCICO ~0.1 across the majority of the star-forming disks of NGC3627 and NGC4321. However, RCICO strongly varies from ~0.05 at the centre of NGC4321 to >0.2-0.5 in NGC1808's starburst centre and NGC7469's centre with an X-ray AGN. Meanwhile, RCICO does not obviously vary with $U$, similar to the prediction of PDR models. We also find a mildly decreasing RCICO with an increasing metallicity over 0.7-0.85 solar metallicity, consistent with the literature. Assuming various typical ISM conditions representing GMCs, active star-forming regions and strong starbursting environments, we calculate the LTE radiative transfer and estimate the [CI/CO] abundance ratio to be ~0.1 across the disks of NGC3627 and NGC4321, similar to previous large-scale findings in Galactic studies. However, this abundance ratio likely has a substantial increase to ~1 and >1-5 in NGC1808's starburst and NGC7469's strong AGN environments, respectively, in line with the expectations for cosmic-ray dominated region (CRDR) and X-ray dominated region (XDR) chemistry. Finally, we do not find a robust evidence for a generally CO-dark, CI-bright gas in the disk areas we probed. (abbreviated)Comment: 23 pages, 13 figures and one table in total (17 pages and 9 figures in main text). Accepted for publication in A&A. For associated data cubes and moment maps, see https://www.canfar.net/storage/vault/list/phangs/RELEASES/DZLIU_etal_202

The Physical Drivers and Observational Tracers of CO-to-H2 Conversion Factor Variations in Nearby Barred Galaxy Centers

The CO-to-H$_2$ conversion factor (\alpha_\rm{CO}) is central to measuring the amount and properties of molecular gas. It is known to vary with environmental conditions, and previous studies have revealed lower \alpha_\rm{CO} in the centers of some barred galaxies on kpc scales. To unveil the physical drivers of such variations, we obtained ALMA Band 3, 6, and 7 observations toward the inner 2 kpc of NGC 3627 and NGC 4321 tracing $^{12}$CO, $^{13}$CO, and C$^{18}$O lines on 100 pc scales. Our multi-line modeling and Bayesian likelihood analysis of these datasets reveal variations of molecular gas density, temperature, optical depth, and velocity dispersion, which are among the key drivers of \alpha_\rm{CO}. The central 300 pc nuclei in both galaxies show strong enhancement of temperature T_\rm{k}>100 K and density n_\rm{H_2}>10^3 cm$^{-3}$. Assuming a CO-to-H$_2$ abundance of $3\times10^{-4}$, we derive 4-15 times lower \alpha_\rm{CO} than the Galactic value across our maps, which agrees well with previous kpc-scale measurements. Combining the results with our previous work on NGC 3351, we find a strong correlation of \alpha_\rm{CO} with low-J $^{12}$CO optical depths (\tau_\rm{CO}), as well as an anti-correlation with T_\rm{k}. The \tau_\rm{CO} correlation explains most of the \alpha_\rm{CO} variation in the three galaxy centers, whereas changes in T_\rm{k} influence \alpha_\rm{CO} to second order. Overall, the observed line width and $^{12}$CO/$^{13}$CO 2-1 line ratio correlate with \tau_\rm{CO} variation in these centers, and thus they are useful observational indicators for \alpha_\rm{CO} variation. We also test current simulation-based \alpha_\rm{CO} prescriptions and find a systematic overprediction, which likely originates from the mismatch of gas conditions between our data and the simulations.Comment: Accepted for publication in ApJ; 30 pages of main text + 3 appendice

ALADIN is Required for the Production of Fertile Mouse Oocytes

Asymmetric cell divisions depend on the precise placement of the spindle apparatus. In mammalian oocytes, spindles assemble close to the cell's center, but chromosome segregation takes place at the cell periphery where half of the chromosomes are expelled into small, nondeveloping polar bodies at anaphase. By dividing so asymmetrically, most of the cytoplasmic content within the oocyte is preserved, which is critical for successful fertilization and early development. Recently we determined that the nucleoporin ALADIN participates in spindle assembly in somatic cells, and we have also shown that female mice homozygously null for ALADIN are sterile. In this study we show that this protein is involved in specific meiotic stages, including meiotic resumption, spindle assembly, and spindle positioning. In the absence of ALADIN, polar body extrusion is compromised due to problems in spindle orientation and anchoring at the first meiotic anaphase. ALADIN null oocytes that mature far enough to be fertilized in vitro are unable to support embryonic development beyond the two-cell stage. Overall, we find that ALADIN is critical for oocyte maturation and appears to be far more essential for this process than for somatic cell divisions

The United States COVID-19 Forecast Hub dataset

Academic researchers, government agencies, industry groups, and individuals have produced forecasts at an unprecedented scale during the COVID-19 pandemic. To leverage these forecasts, the United States Centers for Disease Control and Prevention (CDC) partnered with an academic research lab at the University of Massachusetts Amherst to create the US COVID-19 Forecast Hub. Launched in April 2020, the Forecast Hub is a dataset with point and probabilistic forecasts of incident cases, incident hospitalizations, incident deaths, and cumulative deaths due to COVID-19 at county, state, and national, levels in the United States. Included forecasts represent a variety of modeling approaches, data sources, and assumptions regarding the spread of COVID-19. The goal of this dataset is to establish a standardized and comparable set of short-term forecasts from modeling teams. These data can be used to develop ensemble models, communicate forecasts to the public, create visualizations, compare models, and inform policies regarding COVID-19 mitigation. These open-source data are available via download from GitHub, through an online API, and through R packages

Nature and evolution of the lithospheric mantle beneath the eastern Central Asian Orogenic Belt : constraints from peridotite xenoliths in the central part of the Great Xing'an Range, NE China

Our knowledge of the lithospheric mantle beneath the Central Asian Orogenic Belt is still sparse. Petrologic, major- and trace-element studies on the peridotite xenoliths from the Cenozoic volcanic fields in the Aershan area, the central part of the Great Xing'an Range, NE China, provide insights into the nature and evolution of the lithospheric mantle beneath the eastern part of the belt. According to the REE patterns of clinopyroxene, these peridotites can be divided into three groups which show clear differences in microstructure, geochemistry and equilibration temperature. Group 1 xenoliths (LREE-depleted patterns of Cpx) are lherzolites, with protogranular microstructure and high modal Cpx (8–13 wt.%), low Cr# in spinel ( 3300, (La/Yb)[N] < 1 and occurrence of amphibole). Group 3 peridotites (convex-up REE patterns of Cpx) comprise both lherzolite and harzburgite; they have porphyroclastic microstructures, and show a broad range of Cpx modes (0–7 wt.%), spinel-Cr# (26.5–71.1), bulk rock CaO and Al₂O₃ contents and temperatures (941–1239 °C). The high TiO₂ contents (up to 1.42 wt.%) in spinels of Group 3 imply the involvement of melt/rock reactions. We suggest that the upwelling of asthenospheric material played a key role in modifying the lithospheric mantle underneath the eastern Central Asian Orogenic Belt, and resulted in mantle heterogeneity, which is characterized by juvenile fertile lithospheric material (e.g. Group 1) mixed with older, moderately refractory relics (e.g. Group 2), with the fertile type dominating the shallower levels.12 page(s

Reservoir-Computing for Dispersion Compensation in Digital Filter Multiple Access PON

Chromatic dispersion (CD) is one of the key limitations of increasing the transmission performance for short-reach transmission. The available optical dispersion-compensation techniques are not favored due to their high complexity and other expenses such as power. Reservoir computing is reviewed as a promising technique to provide equalization with memory in an easily trainable fashion, and the properties of the reservoir network are directly linked to system performance. In this article, the digital reservoir computing (RC) based CD-compensation technique is investigated to enhance the transmission performance for digital filter multiple access passive optical network (PON). Numerical results show within 50-km single mode fiber transmission distance for 16 GHz signal bandwidth, the RC-based technique is effective for CD compensation to improve the capacity by 25&#x0025;