Abstract We present the analysis of 16 classical T Tauri stars (CTTSs) using LAMOST and TESS data, investigating spectral properties, photometric variations, and mass accretion rates. All 16 stars ...exhibit emissions in H α lines, from which the average mass accretion rate of 1.76 × 10 −9 M ⊙ yr −1 is derived. Two of the stars, DL Tau and Haro 6-13, show mass accretion bursts simultaneously in TESS, ASAS-SN, and/or the ZTF survey. Based on these observations, we find that the mass accretion rates of DL Tau and Haro 6-13 reach their maxima of 2.5 × 10 −8 M ⊙ yr −1 and 2 × 10 −10 M ⊙ yr −1 , respectively, during the TESS observation. We detect 13 flares among these stars. The flare frequency distribution shows that the CTTSs’ flare activity is not only dominated by strong flares with high energy but also much more active than those of solar-type and young low-mass stars. By comparing the variability classes reported in the literature, we find that the transition timescale between different classes of variability in CTTSs, such as from stochastic (S) to bursting (B) or from quasi-periodic symmetric to quasi-periodic dipping, may range from 1.6 to 4 yr. We observe no significant correlation between inclination and mass accretion rates derived from the emission indicators. This suggests that inner disk properties may be more important than those of outer disks. Finally, we find a relatively significant positive correlation between the asymmetric metric M and the cold disk inclination compared to the literature. A weak negative correlation between the periodicity metric Q value and inclination has also been found.
Abstract In Data Release 9 of LAMOST, we present measurements of v sin i for a total of 121,698 stars measured using the Medium Resolution Spectrograph (MRS) and 80,108 stars using the Low Resolution ...Spectrograph (LRS). These values were obtained through a χ 2 minimization process, comparing LAMOST spectra with corresponding grids of synthetically broadened spectra. Due to the resolution and the spectral range of LAMOST, v sin i measurements are limited to stars with an effective temperature ( T eff ) ranging from 5000 to 8500 K for MRS and 7000 to 9000 K for LRS. The detectable v sin i for MRS is set between 27 and 350 km s −1 , and for LRS between 110 and 350 km s −1 . This limitation is because the convolved reference spectra become less informative beyond 350 km s −1 . The intrinsic precision of v sin i , determined from multiepoch observations, is approximately ∼4.0 km s −1 for MRS and ∼10.0 km s −1 for LRS at a signal-to-noise ratio greater than 50. Our v sin i values show consistency with those from APOGEE17, displaying a scatter of 8.79 km s −1 . They are also in agreement with measurements from the Gaia DR3 and Sun et al. catalogs. An observed trend in LAMOST MRS data is the decrease in v sin i with a drop in T eff , particularly transiting around 7000 K for dwarfs and 6500 K for giants, primarily observed in stars with near-solar abundances.
Electrolyte additive is an effective strategy to inhibit the uncontrolled growth of Li dendrites for lithium metal batteries (LMBs). However, most of the additives are complex synthesis and prone to ...decompose in cycling. Herein, in order to guide the homogeneous deposition of Li+, carbonized polymer dots (CPDs) as electrolyte additives are successfully designed and synthesized by microwave (M‐CPDs) and hydrothermal (H‐CPDs) approaches. The controllable functional groups containing N or O (especially pyridinic‐N, pyrrolic‐N, and carboxyl group) enable CPDs to keep stable in electrolytes for at least 3 months. Meanwhile, the clusters formed between CPDs and Li+ through electrostatic interaction effectively guide the uniform Li dispersion and limit the “tip effect” and dendrite formation. Moreover, as lithiophilic groups increase, the strong electrostatic interference for the solvation effect of Li+ in the electrolyte is formed, which induces faster Li+ diffusion/transfer. As expected, H‐CPDs achieve the ultra‐even Li+ transfer. The corresponding Li//LiFePO4 full cell delivers a high capacity retention rate of 93.8% after 200 cycles, which is much higher than that of the cells without additives (61.2%) and with M‐CPDs (83.7%) as additives. The strategy in this work provides a theoretical direction for CPDs as electrolyte additives used in energy storage devices.
Two kinds of carbonized polymer dots (CPDs) (M‐CPDs and H‐CPDs) as electrolyte additives are successfully designed and synthesized. H‐CPDs with more pyridinic‐N, pyrrolic‐N, and COOH deliver more even Li+ flux through abundant H‐CPDs‐Li clusters bound by strong electrostatic interaction. The symmetrical cell exhibits enhanced cycling stability of 3700 h.
MicroRNAs (miRNAs/miRs) are post‑transcriptional regulators that serve important roles in osteoclastogenesis and bone metabolism; however, the roles of miRNAs have not been completely clarified. The ...present study aimed to investigate the effects of miR‑100‑5p on the mechanism of liver‑bone endocrine metabolism. A miRNA microarray analysis was conducted to evaluate the miRNA expression profile during receptor activator of nuclear factor‑κB ligand‑stimulated osteoclastogenesis. Hematoxylin and eosin and tartrate‑resistant acid phosphatase staining were performed to analyze the trabecular bone microstructure and osteoclast differentiation. The mRNA and protein expression levels were assessed by reverse transcription‑quantitative polymerase chain reaction and western blotting, respectively. The results revealed that in vitro osteoclast differentiation and in vivo bone resorption were suppressed by miR‑100‑5p overexpression. In vivo, a decrease in miR‑100‑5p and an increase in FGF21 were simultaneously observed in mice following ovariectomy (OVX). Bioinformatics analysis and experimental data confirmed that FGF21 was a direct target of miR‑100‑5p. Conversely, augmentation of miR‑100‑5p using a specific agomir in OVX‑operated mice decreased the levels of FGF21 in the serum and liver, and prevented osteoclastogenesis and bone loss. The present study revealed that FGF21 may be a signal molecule associated with the mechanism of liver‑bone endocrine metabolism and may be targeted by miR‑100‑5p. In addition, miR‑100‑5p may serve an important role in protecting against OVX‑induced osteoporosis.
Abstract
Green Pea and Blueberry galaxies are well known for their compact size, low mass, strong emission lines, and analogs to high-
z
Ly
α
-emitting galaxies. In this study, 1547 strong O
iii
λ
...5007 emission-line compact galaxies with 1694 spectra are selected from LAMOST DR9 at the redshift range from 0.0 to 0.59. According to the redshift distribution, these samples can be separated into three groups: Blueberries, Green Peas, and Purple Grapes. Optical Mg
ii
λ
2800 line feature, BPT diagram, multiwavelength spectral energy distribution (SED) fitting, mid-IR (MIR) color, and MIR variability are deployed to identify 23 active galactic nucleus candidates from these samples, which are excluded for the following star formation rate (SFR) discussions. We perform the multiwavelength SED fitting with GALEX UV and WISE MIR data. Color excess from the Balmer decrement shows that these strong O
iii
λ
5007 emission-line compact galaxies are not highly reddened. The stellar mass of the galaxies is obtained by fitting LAMOST calibrated spectra with the emission lines masked. We find that the SFR is increasing with the increase of redshift, while for the sources within the same redshift bin the SFR increases with mass with a similar slope to the star-forming main sequence. These samples have a median metallicity of 12 + log(O/H) of 8.10. The metallicity increases with mass, and all the sources are below the mass–metallicity relation. The direct-derived
T
e
-based metallicity from the O
iii
λ
4363 line agrees with the empirical N2-based empirical gas-phase metallicity. Moreover, these compact strong O
iii
λ
5007 lines are mostly in a less dense environment.
In this study, cellulose acetate (CA)/cellulose nanofibril (CNF) film was prepared via solvent casting. CNF was used as reinforcement to increase tensile properties of CA film. CNF ratio was varied ...into 3, 5, and 10 phr (parts per hundred rubbers). Triacetin (TA) and triethyl citrate (TC) were used as two different eco-friendly plasticizers. Two different types of solvent, which are acetone and N-methyl-2-pyrrolidone (NMP), were also used. CA/CNF film was prepared by mixing CA and CNF in acetone or NMP with 10% concentration and stirred for 24 h. Then, the solution was cast in a polytetrafluoroethylene (PTFE) dish followed by solvent evaporation for 12 h at room temperature for acetone and 24 h at 80 °C in an oven dryer for NMP. The effect of solvent type, plasticizers type, and CNF amount on film properties was studied. Good dispersion in NMP was evident from the morphological study of fractured surface and visible light transmittance. The results showed that CNF has a better dispersion in NMP which leads to a significant increase in tensile strength and elastic modulus up to 38% and 65%, respectively, compared with those of neat CA. CNF addition up to 5 phr loading increased the mechanical properties of the film composites.
In this work, we present a catalog of 2651 carbon stars from the fourth Data Release (DR4) of the Large Sky Area Multi-Object Fiber Spectroscopy Telescope (LAMOST). Using an efficient ...machine-learning algorithm, we find these stars from more than 7 million spectra. As a by-product, 17 carbon-enhanced metal-poor turnoff star candidates are also reported in this paper, and they are preliminarily identified by their atmospheric parameters. Except for 176 stars that could not be given spectral types, we classify the other 2475 carbon stars into five subtypes: 864 C-H, 226 C-R, 400 C-J, 266 C-N, and 719 barium stars based on a series of spectral features. Furthermore, we divide the C-J stars into three subtypes, C-J(H), C-J(R), and C-J(N), and about 90% of them are cool N-type stars as expected from previous literature. Besides spectroscopic classification, we also match these carbon stars to multiple broadband photometries. Using ultraviolet photometry data, we find that 25 carbon stars have FUV detections and that they are likely to be in binary systems with compact white dwarf companions.
Developing flexible electrodes with high active materials loading and excellent mechanical stability is of importance to flexible electronics, yet remains challenging. Herein, robust flexible ...electrodes with an encapsulated core‐multishell structure are developed via a spraying‐hydrothermal process. The multilayer electrode possesses an architecture of substrate/reduced graphene oxide (rGO)/bimetallic complex/rGO/bimetallic complex/rGO from the inside to the outside, where the cellulosic fibers serve as the substrate, namely, the core; and the multiple layers of rGO and bimetallic complex, are used as active materials, namely, the shells. The inner two rGO interlayers function as the cement that chemically bind to two adjacent layers, while the two outer rGO layers encapsulate the inside structure effectively protecting the electrode from materials detachment or electrolyte corrosion. The electrodes with a unique core‐multishell structure exhibit excellent cycle stability and exceptional temperature tolerance (−25 to 40 °C) for lithium and sodium storage. A combination of experimental and theoretical investigations are carried out to gain insights into the synergetic effects of cobalt‐molybdenum‐sulfide (CMS) materials (the bimetallic complex), which will provide guidance for future exploration of bimetallic sulfides. This strategy is further demonstrated in other substrates, showing general applicability and great potential in the development of flexible energy storage devices.
The encapsulated core–multishell structure with an architecture of substrate/reduced graphene oxide (rGO)/bimetallic complex/rGO/bimetallic complex/rGO is used to fabricate robust and high energy density electrodes for lithium/sodium storage, with a high proportion of active material (20 wt%) and mechanical strength. The underlying synergistic effect of bimetal ions is revealed via experimental investigations and theoretical calculations.
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•Oxidation voltage was varied to optimize film transmittance and cyclability.•Over-oxidation induced a severe degradation of thiophene moieties in P3HT films.•Optical memory ...utilization enhanced cyclability and lowered the energy consumption.
Herein, we report the effects of applied voltage on the electrochromic (EC) stability of poly(3-hexylthiophene) (P3HT) films during EC reactions. The transmittance difference and cycling stability of these films were monitored to optimize the oxidation voltage, and their chemical compositions were analyzed by X-ray photoelectron spectroscopy after long-term electrochemical cycling. High oxidation voltages increased the color contrast of P3HT films but decreased their cycling stability due to facilitating chemical degradation. Furthermore, at an optimized oxidation voltage, the retention time during potential pulsing was adjusted utilizing the optical memory of P3HT, revealing that the decreased voltage application time reduced power consumption by 9.6% and enhanced EC stability without loss of color contrast.
Extrusion process using 1-ethyl-3-methylimidazolium acetate (EMIMAc) in co-solvent, dimethyl sulfoxide (DMSO), was conducted to improve the pretreatment effect on the enzymatic saccharification of ...pussy willow (
Salix gracilistyla
Miq.). The use of a twin screw extruder capable of continuous processing increased the solid loading to 50% in EMIMAc and its co-solvent DMSO. The water-soluble fraction was increased by increasing the EMIMAc amount in co-solvent and the extrusion temperature but decreasing the screw rotating speed and solid loading. The surface morphologies of the extruded product showed remarkable disruption of the cell wall structures and fibrillation with increasing amounts of EMIMAc in co-solvent. With increasing EMIMAc amount in co-solvent and extrusion temperature and with decreasing screw rotating speed and solid loading, the crystalline structure of cellulose was more disrupted, resulting in the increase in saccharification yield. The highest yield of glucose and xylose was 99.0% and 99.5%, respectively, from the pretreated products using only EMIMAc under solid loading of 15% at 160 °C extrusion temperature and 5 rpm screw rotating speed. The initial saccharification rate was faster in the pretreated product precipitated in alcohol and acetone than in water.
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![Strong [O iii] λ5007 Emissi...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0004-637X/small "Strong [O iii] λ5007 Emission-line Compact Galaxies in LAMOST DR9: Blueberries, Green Peas, and Purple Grapes")
