Abstract
We present the fourth Open Gravitational-wave Catalog (4-OGC) of binary neutron star (BNS), binary black hole (BBH), and neutron star–black hole (NSBH) mergers. The catalog includes ...observations from 2015 to 2020 covering the first through third observing runs (O1, O2, O3a, and O3b) of Advanced LIGO and Advanced Virgo. The updated catalog includes seven BBH mergers that were not previously reported with high significance during O3b for a total of 94 observations: 90 BBHs, 2 NSBHs, and 2 BNSs. The most confident new detection, GW200318_191337, has component masses
49.1
−
12.0
+
16.4
M
⊙
and
31.6
−
11.6
+
12.0
M
⊙
;
its redshift of
0.84
−
0.35
+
0.4
(90% credible interval) may make it the most distant merger so far. We estimate the merger rate of BBH sources, assuming a power-law mass distribution containing an additive Gaussian peak, to be
16.5
−
6.2
+
10.4
(
25.0
−
8.0
+
12.6
)
Gpc
−3
yr
−1
at a redshift of
z
= 0 (0.2). For BNS and NSBH sources, we estimate a merger rate of
200
−
148
+
309
Gpc
−3
yr
−1
and
19
−
14
+
30
Gpc
−3
yr
−1
, respectively, assuming the known sources are representative of the total population. We provide reference parameter estimates for each of these sources using an up-to-date model accounting for instrumental calibration uncertainty. The corresponding data release also includes our full set of subthreshold candidates.
Abstract
We present the third open gravitational-wave catalog (3-OGC) of compact-binary coalescences, based on the analysis of the public LIGO and Virgo data from 2015 through 2019 (O1, O2, O3a). Our ...updated catalog includes a population of 57 observations, including 4 binary black hole mergers that had not been previously reported. This consists of 55 binary black hole mergers and the 2 binary neutron star mergers, GW170817 and GW190425. We find no additional significant binary neutron star or neutron star–black hole merger events. The most confident new detection is the binary black hole merger GW190925_232845, which was observed by the LIGO–Hanford and Virgo observatories with
astro
>
0.99
;
its primary and secondary component masses are
20.2
−
2.5
+
3.9
M
⊙
and
15.6
−
2.6
+
2.1
M
⊙
, respectively. We estimate the parameters of all binary black hole events using an up-to-date waveform model that includes both subdominant harmonics and precession effects. To enable deep follow up as our understanding of the underlying populations evolves, we make available our comprehensive catalog of events, including the subthreshold population of candidates, and the posterior samples of our source parameter estimates.
Background
Microsurgical bone reconstruction is challenging in cases of anterior maxillary defects because of the presence of residual teeth. The study analyzed the method and feasibility of using ...vascularized bone flaps to reconstruct anterior maxillary defects.
Methods
We retrospectively analyzed 15 patients treated at the Department of Oral and Maxillofacial Surgery, Peking University School, and Hospital of Stomatology between November 2017 and January 2023.
Results
A total of 14 patients were successfully reconstructed using the digital technique: 6 deep circumflex iliac artery (DCIA) flaps and 8 fibular free flaps. Palatal and buccal pedicle paths were used in 4 and 10 cases, respectively, for vascular anastomosis. The implant coverage rates of the DCIA and fibular free flaps were 87.2% and 92.6%, respectively (p > 0.05).
Conclusion
Anterior maxillary defects reconstructed with the DCIA and fibular free flaps are reliable methods. Furthermore, the palatal and buccal paths are recommended for vascular anastomosis.
Current methods for skeleton-based human action recognition usually work with complete skeletons. However, in real scenarios, it is inevitable to capture incomplete or noisy skeletons, which could ...significantly deteriorate the performance of current methods when some informative joints are occluded or disturbed. To improve the robustness of action recognition models, a multi-stream graph convolutional network (GCN) is proposed to explore sufficient discriminative features spreading over all skeleton joints, so that the distributed redundant representation reduces the sensitivity of the action models to non-standard skeletons. Concretely, the backbone GCN is extended by a series of ordered streams which is responsible for learning discriminative features from the joints less activated by preceding streams. Here, the activation degrees of skeleton joints of each GCN stream are measured by the class activation maps (CAM), and only the information from the unactivated joints will be passed to the next stream, by which rich features over all active joints are obtained. Thus, the proposed method is termed richly activated GCN (RA-GCN). Compared to the state-of-the-art (SOTA) methods, the RA-GCN achieves comparable performance on the standard NTU RGB+D 60 and 120 datasets. More crucially, on the synthetic occlusion and jittering datasets, the performance deterioration due to the occluded and disturbed joints can be significantly alleviated by utilizing the proposed RA-GCN.
Slot‐die coating is recognized as the most compatible method for the roll‐to‐roll (R2R) processing of large‐area flexible organic solar cells (OSCs). However, the photovoltaic performance of ...large‐area flexible OSC lags significantly behind that of traditional spin‐coating devices. In this work, two acceptors, Qx‐1 and Qx‐2, show quite different film‐formation kinetics in the slot‐die coating process. In situ absorption spectroscopy indicates that the excessive crystallinity of Qx‐2 provides early phase separation and early aggregation, resulting in oversized crystal domains. Consequently, the PM6:Qx‐1‐based 1 cm2 flexible device exhibits an excellent power conversion efficiency (PCE) of 13.70%, which is the best performance among the slot‐die‐coated flexible devices; in contrast, the PM6:Qx‐2 blend shows a pretty poor efficiency, which is lower than 1%. Moreover, the 30 cm2 modules based on PM6:Qx‐1, containing six 5 cm2 sub‐cells, exhibit a PCE of 12.20%. After being stored in a glove box for over 6000 h, the PCE remains at 103% of its initial values, indicating excellent shelf stability. Therefore, these results show a promising future strategy for the upscaling fabrication of flexible large‐area OSCs.
In situ absorption measurement is used to investigate the aggregation behavior of acceptors during slot‐die‐coating. The 1 cm2 flexible device can reach a power conversion efficiency of 13.70%, with excellent shelf stability and upscaling ability. The connected modules (180 cm2) can effectively power a smartphone, showing great potential for future applications.
Electrochemical reduction of CO2 (CO2RR) is a promising solution to mitigate the ever‐increasing global carbon emission. Indium‐based catalysts have been extensively studied for catalyzing the ...production of formate, CO, and even multi‐carbon molecules from CO2. Rational design of the catalyst, however, is urgently needed to further improve the activity, selectivity, and stability for the sake of commercialization. Herein, we comprehensively reviewed recent progresses on the indium based CO2RR catalysts. Specifically, aspects regarding the nature of active sites, reaction mechanism, and the impact of operating conditions are overviewed. The reported indium‐based monometallic and bimetallic catalysts in the literature are summarized, as well. Future directions should be focused on the understanding of catalyst system during the reaction and under industrial‐relevant conditions.
Electro – Iridium! This work reviews the recent advances on indium‐based catalysts for electrochemical CO2 reduction. The nature of active sites, reaction mechanism and the effect of operating conditions are discussed. Indium‐based monometallic, bimetallic and chalcogenides catalysts for the production of CO or formate are summarized. Future directions regarding the understanding and rational design of indium‐based electrocatalysts are proposed.
Molecular complexes with inexpensive transition‐metal centers have drawn extensive attention, as they show a high selectivity in the electrochemical conversion of CO2 to CO. In this work, we propose ...a new strategy to covalently graft cobalt porphyrin onto the surface of a carbon nanotube by a substitution reaction at the metal center. Material characterization and electrochemical studies reveal that the porphyrin molecules are well dispersed at a high loading of 10 wt. %. As a result, the turnover frequency for CO formation is improved by a factor of three compared to traditional physically‐mixed catalysts with the same cobalt content. This leads to an outstanding overall current density of 25.1 mA cm−2 and a Faradaic efficiency of 98.3 % at 490 mV overpotential with excellent long‐term stability. This work provides an effective pathway for the improvement of the performance of electrocatalysts that could inspire rational design of molecular catalysts in the future.
Highly dispersed: The covalent attachment of cobalt porphyrin onto carbon nanotubes is achieved by a substitution reaction at the metal center. This leads to large improvements in the efficiency of electrochemical CO2 reduction compared to systems where the compounds are physically mixed.
Abstract
Einstein's general relativity, as the most successful theory of gravity, is one of the cornerstones of modern physics. However, the experimental tests for gravity in the high energy region ...are limited. The emerging gravitational-wave astronomy has opened an avenue for probing the fundamental properties of gravity in a strong and dynamical field, and in particular, a high energy regime. In this work, we test the parity conservation of gravity with gravitational waves. If the parity symmetry is broken, the left- and right-handed modes of gravitational waves would follow different equations of motion, dubbed as birefringence. We perform full Bayesian inference by comparing the state-of-the-art waveform with parity violation with the compact binary coalescence data released by LIGO and Virgo collaboration. We do not find any violations of general relativity, thus constrain the lower bound of the parity-violating energy scale to be 0.09 GeV through the velocity birefringence of gravitational waves. This provides the most stringent experimental test of gravitational parity symmetry to date. We also find third generation gravitational-wave detectors can enhance this bound to
GeV if there is still no violation, comparable to the current energy scale in particle physics, which indicates gravitational-wave astronomy can usher in a new era of testing the ultraviolet behavior of gravity in the high energy region.
Abstract
We present a search for gravitational waves from subsolar mass compact-binary mergers that allows for nonnegligible orbital eccentricity. Subsolar mass black holes are a signature of ...primordial origin black holes, which may be a component of dark matter. To produce binary coalescences, primordial black holes may form close binaries either in the early universe or more recently through dynamical interactions. A signature of dynamical formation would be the observation of noncircularized orbits. We search for black hole mergers where the primary mass is 0.1–7
M
⊙
and the secondary mass is 0.1–1
M
⊙
. We allow for eccentricity up to ∼0.3 at a dominant-mode gravitational-wave frequency of 10 Hz for binaries with component masses >0.5
M
⊙
. We find no convincing candidates in the public LIGO data from 2015–2017. The two most promising candidates have a false alarm rate of 1 per 3 and 4 yr, respectively, which combined is only a ∼2.4
σ
deviation from the expected Poisson rate. Given the marginal statistical significance, we place upper limits on the rate of subsolar mass mergers under the assumption of a null observation and compare how these limits may inform the possible dark matter contribution.
In recent years, micrometer‐sized Si‐based anode materials have attracted intensive attention in the pursuit of energy‐storage systems with high energy and low cost. However, the significant volume ...variation during repeated electrochemical (de)alloying processes will seriously damage the bulk structure of SiOx microparticles, resulting in rapid performance fade. This work proposes to address the challenge by preparing in situ magnesium‐doped SiOx (SiMgyOx) microparticles with stable structural evolution against Li uptake/release. The homogeneous distribution of magnesium silicate in SiMgyOx contributes to building a bonding network inside the particle so that it raises the modulus of lithiated state and restrains the internal cracks due to electrochemical agglomeration of nano‐Si. The prepared micrometer‐sized SiMgyOx anode shows high reversible capacities, stable cycling performance, and low electrode expansion at high areal mass loading. A 21700 cylindrical‐type cell based on the SiMgyOx‐graphite anode and LiNi0.8Co0.15Al0.05O2 cathode demonstrates a 1000‐cycle operation life using industry‐recognized electrochemical test procedures, which meets the practical storage requirements for consumer electronics and electric vehicles. This work provides insights on the reasonable structural design of micrometer‐sized alloying anode materials toward realization of high‐performance Li‐ion batteries.
The in situ element doping approach developed in this research provides not only a promising material (SiMgyOx) as high‐performance Li‐ion battery anodes with superior properties and low industrialization cost for commercial applications, but also insights on the reasonable structural design of micrometer‐sized alloying anode materials for restraining internal cracks and improving electrochemical performance.
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