Designing highly conducting metal-organic frameworks (MOFs) is currently a subject of great interest for their potential applications in diverse areas encompassing energy storage and generation. ...Herein, a strategic design in which a metal-sulfur plane is integrated within a MOF to achieve high electrical conductivity, is successfully demonstrated. The MOF {Cu
(6-Hmna)(6-mn)·NH
}
(1, 6-Hmna = 6-mercaptonicotinic acid, 6-mn = 6-mercaptonicotinate), consisting of a two dimensional (-Cu-S-)
plane, is synthesized from the reaction of Cu(NO
)
, and 6,6'-dithiodinicotinic acid via the in situ cleavage of an S-S bond under hydrothermal conditions. A single crystal of the MOF is found to have a low activation energy (6 meV), small bandgap (1.34 eV) and a highest electrical conductivity (10.96 S cm
) among MOFs for single crystal measurements. This approach provides an ideal roadmap for producing highly conductive MOFs with great potential for applications in batteries, thermoelectric, supercapacitors and related areas.
Abstract
Monitoring mass accretion onto substellar objects provides insights into the geometry of the accretion flows. We use the Lulin One-meter Telescope to monitor H
α
emission from FU Tau B, a ...∼19
M
Jup
brown-dwarf companion at 5.″7 (719 au) from the host star, for six consecutive nights. This is the longest continuous H
α
monitoring for a substellar companion near the deuterium-burning limit. We aim to investigate if accretion near the planetary regime could be rotationally modulated as suggested by magnetospheric accretion models. We find tentative evidence that H
α
mildly varies on hourly and daily timescales, though our sensitivity is not sufficient to definitively establish any rotational modulation. No burst-like events are detected, implying that accretion onto FU Tau B is overall stable during the time baseline and sampling windows over which it was observed. The primary star FU Tau A also exhibits H
α
variations over timescales from minutes to days. This program highlights the potential of monitoring accretion onto substellar objects with small telescopes.
The Jupiter-family comet (JFC) 46P/Wirtanen passed the Earth at a distance of 0.077 au on 2018 December 16 UT, presenting a rare opportunity to study the chemical structure of its coma. With the ...James Clerk Maxwell Telescope we achieved a resolution of 800 km, which is smaller than the scale lengths of some distributed cometary molecules at the comet's heliocentric distance of 1 au. Spectroscopic observations of the J = 4 − 3 transition of HCN showed generally uniform levels of outgassing activity during the observing period, 2018 December 14-20. Gas expansion velocities were ∼0.6 km s−1, and the derived average HCN production rate was 7.4 × 1024 mol s−1. HCN and CH3OH emissions were detected at least 30″ (1600 km) from the nucleus, and the abundances of these species were typical for a JFC. The radial distribution of CH3OH is consistent with an extended source of sublimation such as a population of icy grains-cometary halo ice primaries, or CHIPs-as has been invoked previously to explain hyperactivity in comets. The abundance of H2CO is normal if it is a daughter species. HNC and CO were not detected, but a sensitive nondetection of CS implies an unusually low CS:H2O ratio of <0.02%. The peak brightness of the 850 m continuum emissions from icy coma dust particles of size ∼1 mm fell from (52 6) to (40 3) mJy beam−1 through the week, while the size of the dust coma remained essentially constant, with dust extending to ∼1000 km from the nucleus. The total mass of those particles was ∼2 × 108 kg.
We searched for rotational lines of H12C14N in comet 46P/Wirtanen, using the Purple Mountain Observatory 13.7 m radio telescope. The J = 1-0 lines of HCN (3.4 mm wavelength) were unambiguously ...detected in 46P during the 2018 December 14-15 period, with a beam resolution of 62 2 and a velocity resolution of ∼0.21 km s−1 per channel. The molecular production rates were computed. The mean HCN(1-0) production rate of 46P was (6.45 1.31) × 1024 molec s−1 in the above two days. We found possible indications of time variation in the outgassing activity. The average HCN abundance relative to water QHCN/ of 46P was (0.09 0.01)%. The HCN line shapes gave primary information on the kinematics of the cometary atmosphere. The HCN linewidths provided a direct determination of the coma expansion velocity, which was about 0.5 0.05 km s−1 at post-perihelion (1.056 au).
Class II histone deacetylases (HDACs) are considered as potential targets to treat Alzheimer's disease (AD). Previously, C-3 substituted phenothiazine-containing compounds with class II ...HDAC-inhibiting activities was found to promote neurite outgrowth. This study replaced phenothiazine moiety with phenoxazine that contains many C-3 and C-4 substituents. Some resulting compounds bearing the C-4 substituent on a phenoxazine ring displayed potent class II HDAC inhibitory activities. Structure-activity relationship (SAR) of these compounds that inhibited HDAC isoenzymes was disclosed. Molecular modelling analysis demonstrates that the potent activities of C-4 substituted compounds probably arise from π-π stacked interactions between these compounds and class IIa HDAC enzymes. One of these, compound 7d exhibited the most potent class II HDAC inhibition (IC
50
= 3-870 nM). Notably, it protected neuron cells from H
2
O
2
-induced neuron damage at sub-μM concentrations, but with no significant cytotoxicity. These findings show that compound 7d is a lead compound for further development of anti-neurodegenerative agents.
We study teleparallel gravity in the original Kaluza–Klein (KK) scenario. Our calculation of the KK reduction of teleparallel gravity indicates that the 5-dimensional torsion scalar T(5) generates ...the non-Brans–Dicke type effective Lagrangian in 4-dimension due to an additional coupling between the derivative of the scalar field and torsion, but the result is equivalent to that in general relativity. We also discuss the cosmological behavior in the FLRW universe based on the effective teleparallel gravity.
The Cassini spacecraft passed within 168.2 kilometers of the surface above the southern hemisphere at 19:55:22 universal time coordinated on 14 July 2005 during its closest approach to Enceladus. ...Before and after this time, a substantial atmospheric plume and coma were observed, detectable in the Ion and Neutral Mass Spectrometer (INMS) data set out to a distance of over 4000 kilometers from Enceladus. INMS data indicate that the atmospheric plume and coma are dominated by water, with significant amounts of carbon dioxide, an unidentified species with a mass-to-charge ratio of 28 daltons (either carbon monoxide or molecular nitrogen), and methane. Trace quantities (<1%) of acetylene and propane also appear to be present. Ammonia is present at a level that does not exceed 0.5%. The radial and angular distributions of the gas density near the closest approach, as well as other independent evidence, suggest a significant contribution to the plume from a source centered near the south polar cap, as distinct from a separately measured more uniform and possibly global source observed on the outbound leg of the flyby.
Tropical cyclones (TCs) cause severe natural hazards and drive intense upper ocean cooling through a series of oceanic and atmospheric physical processes, including vertical mixing and upwelling. ...Among these processes, TC-induced warming of near-surface waters in the open ocean has rarely been noted. This study provides a detailed analysis of upper ocean responses to 30 TC events observed by two buoys in the western North Pacific between 2016 and 2021. Supplemented with numerical experiments, we suggest that downwelling frequently occurs at the periphery of upwelling regions (around the radius of the 34 knot wind speed) following the passage of a TC. Downwelling is identified via pronounced warm anomalies under a shallow mixed layer depth, and its dynamics are attributed to negative wind stress curl and current-induced convergence. These findings highlight the important role played by TC-induced downwelling and offer insights for reconsidering the influence of TCs on biogeochemical processes.
•Integrating UAV imagery with object detection and semantic segmentation.•Generating a visualized growth map on a single-plant basis using deep learning.•Detecting uneven irrigation/fertilization and ...necrosis and apoptosis for broccoli cultivation.•Determining the optimal amount of fertilization and the optimal harvest time.
Single-plant growth monitoring aids precision agricultural decision-making to reduce the costs related to pesticides, fertilizers, and labor. This study integrated visible/multi-spectral UAV imagery with two deep learning methods, object detection and semantic segmentation, to obtain a visualized map that could assist in precise field monitoring and management for broccoli cultivation. For plant detection, feature extraction was conducted using multiscale dilated convolution, which enabled the effective detection of broccoli in images taken under different photographic conditions and resolutions. Two crops of broccoli (cultivar: Broccoli No. 42) were planted in 2020 at Taichung Agricultural Research and Extension Station, in which the first crop was treated as the training data. The detection of individual broccoli plants was processed using a feature extraction architecture of the AlexNet-Like backend at the SSD frontend, where the input scale of the detector complies with the original SSD architecture. For the model test on the second crop, the recall and precision were 98.58% and 99.73%, respectively, after histogram matching based on the first crop images. Moreover, the proposed approach was applied to a real farming field to verify its robustness across different conditions, and achieved a recall of 61.13% using dilated convolution. This study also generated a visualized growth map on a single-plant basis, which allows operators to detect growth situations, such as uneven irrigation or fertilization and necrosis and apoptosis, to greatly enhance the viability of precision agriculture in the calculation of unit yield and intragroup differences for a regime. The proposed approach can be used to determine the optimal amount of fertilization and observe the size of broccoli heads to determine the optimal harvest time. Expectedly, the method may also be applied to the monitoring and management of other crops to improve the efficiency and reduce the labor demand for precision agriculture.
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