Understanding the breakdown mechanisms of polymer-based dielectrics is critical to achieving high-density energy storage. Here a comprehensive phase-field model is developed to investigate the ...electric, thermal, and mechanical effects in the breakdown process of polymer-based dielectrics. High-throughput simulations are performed for the P(VDF-HFP)-based nanocomposites filled with nanoparticles of different properties. Machine learning is conducted on the database from the high-throughput simulations to produce an analytical expression for the breakdown strength, which is verified by targeted experimental measurements and can be used to semiquantitatively predict the breakdown strength of the P(VDF-HFP)-based nanocomposites. The present work provides fundamental insights to the breakdown mechanisms of polymer nanocomposite dielectrics and establishes a powerful theoretical framework of materials design for optimizing their breakdown strength and thus maximizing their energy storage by screening suitable nanofillers. It can potentially be extended to optimize the performances of other types of materials such as thermoelectrics and solid electrolytes.
Abstract
We present an estimate of the occurrence rate of hot Jupiters (7
R
⊕
≤
R
p
≤ 2
R
J
, 0.8 ≤
P
b
≤ 10 days) around early-type M dwarfs based on stars observed by the Transiting Exoplanet ...Survey Satellite (TESS) during its primary mission. We adopt stellar parameters from the TESS Input Catalog and construct a sample of 60,819 M dwarfs with 10.5 ≤
T
mag
≤ 13.5, effective temperatures 2900 ≤
T
eff
≤ 4000 K, and stellar masses 0.45 ≤
M
*
≤ 0.65
M
⊙
. We conduct a uninformed transit search using a detection pipeline based on the box least square search and characterize the searching completeness through an injection and recovery experiment. We combine a series of vetting steps including light centroid measurement, odd/even and secondary eclipse analysis, rotation and transit period synchronization tests as well as inspecting the ground-based photometric, spectroscopic, and imaging observations. Finally, we find a total of nine planet candidates, all of which are known TESS objects of interest. We obtain an occurrence rate of 0.27% ± 0.09% for hot Jupiters around early-type M dwarfs that satisfy our selection criteria. Compared with previous studies, the occurrence rate of hot Jupiters around early-type M dwarfs is smaller than all measurements for FGK stars, although they are consistent within 1
σ
–2
σ
. There is a trend that the occurrence rate of hot Jupiters has a peak at G dwarfs and falls toward both hotter and cooler stars. Combining results from transit, radial velocity, and microlensing surveys, we find that hot Jupiters around early-type M dwarfs possibly show a steeper decrease in the occurrence rate per logarithmic semimajor axis bin (
dN
/
d
log
10
a
) when compared with FGK stars.
We propose a pebble-driven core accretion scenario to explain the formation of giant planets around the late-M dwarfs of $M_ star odot $. In order to explore the optimal disk conditions for giant ...planet, we performed N-body simulations to investigate the growth and dynamical evolution of both single and multiple protoplanets in the disks with both inner viscously heated and outer stellar irradiated regions. The initial masses of the protoplanets are either assumed to be equal to $0.01 \ oplus $ or calculated based on the formula derived from streaming instability simulations.
Our findings indicate that massive planets are more likely to form in disks with longer lifetimes, higher solid masses, moderate to high levels of disk turbulence, and larger initial masses of protoplanets. In the single protoplanet growth cases, the highest planet core mass that can be reached is generally lower than the threshold necessary to trigger rapid gas accretion, which impedes the formation of giant planets.
Nonetheless, in multi-protoplanet cases, the cores can exceed the pebble isolation mass barrier aided by frequent planet-planet collisions. This consequently speeds their gas accretion up and promotes giant planet formation, making the optimal parameter space to grow giant planets substantially wider. Taken together, our results suggest that even around very-low-mass stellar hosts, the giant planets with orbital periods of $ lesssim 100$ days are still likely to form when lunar-mass protoplanets first emerge from planetesimal accretion and then grow rapidly by a combination of pebble accretion and planet-planet collisions in disks with a high supply of a pebble reservoir $ oplus $ and a turbulent level of $ t sim
To understand the changes in gene expression that occur as a result of age, which might create a permissive or causal environment for age-related diseases, we produce a multi-time point age-related ...gene expression signature (AGES) from liver, kidney, skeletal muscle, and hippocampus of rats, comparing 6-, 9-, 12-, 18-, 21-, 24-, and 27-month-old animals. We focus on genes that changed in one direction throughout the lifespan of the animal, either early in life (early logistic changes), at mid-age (mid-logistic), late in life (late-logistic), or linearly, throughout the lifespan of the animal. The pathways perturbed because of chronological age demonstrate organ-specific and more-global effects of aging and point to mechanisms that could potentially be counter-regulated pharmacologically to treat age-associated diseases. A small number of genes are regulated by aging in the same manner in every tissue, suggesting they may be more-universal markers of aging.
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•A multi-tissue age-related gene expression signature (AGES) is constructed•Linear, early, middle-, and late-life expression changes are discovered•AGES points to potential mechanisms inducing age-related disorders•Gene changes in multiple tissues include upregulation of interferon signaling
Shavlakadze et al. studied gene expression changes occurring because of aging throughout the lifespan of rats, examining liver, skeletal muscle, kidney, and the hippocampus. The study should serve as a valuable resource for the discovery of biomarkers and mediators of age-related disorders.
Abstract
We propose a second-order statistic parameter
ε
, the relative occurrence rate between hot Jupiters (HJs) and cold Jupiters (CJs) (
ε
=
η
HJ
/
η
CJ
), to probe the migration of gas giants. ...Since the planet occurrence rate is the combined outcome of the formation and migration processes, a joint analysis of HJ and CJ frequency may shed light on the dynamical evolution of giant planet systems. We first investigate the behavior of
ε
as the stellar mass changes observationally. Based on the occurrence rate measurements of HJs (
η
HJ
) from the Transiting Exoplanet Survey Satellite survey and CJs (
η
CJ
) from the California Legacy Survey, we find a tentative trend (97% confidence) that
ε
drops when the stellar mass rises from 0.8 to 1.4
M
⊙
, which can be explained by different giant planet growth and disk migration timescales around different stars. We carry out planetesimal and pebble accretion simulations, both of which can reproduce the results of
η
HJ
,
η
CJ
, and
ε
. Our findings indicate that the classical core accretion + disk migration model can explain the observed decreasing trend of
ε
. We propose two ways to increase the significance of the trend and verify the anticorrelation. Future works are required to better constrain
ε
, especially for M dwarfs and for more massive stars.
In-vitro-transcribed messenger RNA (mRNA) has recently shown increasing significance in the development of vaccines and therapeutics. Immunogenic double-stranded RNA (dsRNA) is an undesired byproduct ...formed during in vitro transcription (IVT), and it is challenging to reduce dsRNA byproduct from mRNA due to their similar sizes and intrinsic characteristics. Removal of dsRNA relies heavily on post-IVT chromatography purifications, such as reverse-phase high-pressure liquid chromatography, which increase manufacturing costs, reduce yield, and often decrease integrity, especially for long mRNA. Thus, it would be ideal to reduce and control the level of dsRNA during IVT. We herein present a simple, scalable, and controllable method to reduce the formation of dsRNA byproducts during IVT. Selected chaotropic agents at optimized concentrations are included during IVT to create a mild denaturing environment to prevent the undesired intermolecular or intramolecular base-pairing that is thought to promote RNA-templated dsRNA formation by RNA polymerase. Compared with regular IVT, our improved method produces mRNA with significantly less dsRNA, much lower immuno-stimulation, and more efficient protein expression. Therefore, this method potentially eliminates dsRNA removal purification steps and does not require reduced magnesium concentration, elevated temperature, or custom reagents, enabling a straightforward, high-yield, and cost-effective scale-up approach for mRNA manufacturing.
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Addition of chaotropic agents to in vitro transcription reactions minimizes the formation of undesired double-stranded RNA byproducts while maintaining yield and transcript integrity, obviating the need for harsh or time-consuming HPLC purification techniques.
The Exoplanet Orbit Database (EOD) compiles orbital, transit, host star, and other parameters of robustly-detected exoplanets reported in the peer-reviewed literature. The EOD can be navigated ...through the Exoplanet Data Explorer (EDE) plotter and table, available on the World Wide Web at exoplanets.org. The EOD contains data for 1492 confirmed exoplanets as of 2014 July. The EOD descends from a table provided by Butler and coworkers in 2002 and the Catalog of Nearby Exoplanets (Butler and coworkers in 2006), and the first complete documentation for the EOD and the EDE was presented by Wright and coworkers in 2011. In this work, we describe our work since then. We have expanded the scope of the EOD to include secondary eclipse parameters and asymmetric uncertainties and expanded the EDE to include the sample of over 3000 Kepler Objects of Interest (KOIs) and other real planets without good orbital parameters (such as many of those detected by microlensing and imaging). Users can download the latest version of the entire EOD as a single comma separated value file from the front page of exoplanets.org.
The age-related effects of GDF11 have been a subject of controversy. Here, we find that elevated GDF11 causes signs of cachexia in mice: reduced food intake, body weight, and muscle mass. GDF11 also ...elicited a significant elevation in plasma Activin A, previously shown to contribute to the loss of skeletal muscle. The effects of GDF11 on skeletal muscle could be reversed by administration of antibodies to the Activin type II receptors. In addition to the effects on muscle, GDF11 increased plasma GDF15, an anorectic agent. The anorexia, but not the muscle loss, could be reversed with a GDF15-neutralizing antibody. GDF15 upregulation is due to GDF11-induced recruitment of SMAD2/3 to the GDF15 promoter. Inhibition of GDF15 can restore appetite but cannot restore the GDF11-induced loss of muscle mass, which requires blockade of ActRII signaling. These findings are relevant for treatment of cachexia.
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•Increased levels of GDF11 cause increased circulating Activin A and GDF15 in mice•Supraphysiologic levels of GDF11 induce cachexia, anorexia, and muscle loss•Blockade of GDF15 spares anorexia, but not muscle loss•Blockade of the GDF11 receptor ActRII spares muscle loss and decreases anorexia
Jones et al. find that high levels of GDF11 in mice induce symptoms of cachexia: skeletal muscle loss and anorexia. The anorexia is due to GDF11-dependent upregulation of GDF15. Downregulation of GDF11 in settings in which it exists at high levels is predicted to be beneficial.
There is a lack of pharmacological interventions available for sarcopenia, a progressive age-associated loss of muscle mass, leading to a decline in mobility and quality of life. We found mTORC1 ...(mammalian target of rapamycin complex 1), a well-established positive modulator of muscle mass, to be surprisingly hyperactivated in sarcopenic muscle. Furthermore, partial inhibition of the mTORC1 pathway counteracted sarcopenia, as determined by observing an increase in muscle mass and fiber type cross-sectional area in select muscle groups, again surprising because mTORC1 signaling has been shown to be required for skeletal muscle mass gains in some models of hypertrophy. Additionally, several genes related to senescence were downregulated and gene expression indicators of neuromuscular junction denervation were diminished using a low dose of a "rapalog" (a pharmacological agent related to rapamycin). Therefore, partial mTORC1 inhibition may delay the progression of sarcopenia by directly and indirectly modulating multiple age-associated pathways, implicating mTORC1 as a therapeutic target to treat sarcopenia.
ABSTRACT
We present a catalogue of 62 polluted white dwarfs observed by the 9th Low-Resolution Data Release of the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST LRS DR9v1; R≈1800) ...and the Early Data Release 3 (EDR3) of the Gaia Mission. Among these stellar remnants, 30 are new discoveries with previously unknown traces of calcium pollution. To generate our catalogue, we used a data base of 4324 unique Gaia EDR3 white dwarf candidates with LAMOST LRS DR9v1 observations, many of which have been spectroscopically confirmed by other telescopes. For these stars, we developed a quantitative method to detect calcium absorption in their spectra between 3900–4000 Å, which we then validated through visual inspection and multiple literature cross-checks. Our catalogue provides the astrometric and photometric properties of the white dwarf candidates, incorporates supplementary data (e.g. Montreal White Dwarf Database, MWDD; PanSTARRS; the Hubble Space Telescope), and indicates the possibility of calcium pollution in their atmospheres. For our final sample of polluted white dwarfs, we also determine the main atmospheric properties of 23 sources with effective temperatures Teff ≤ 25 000 K and no existing calcium abundances in the MWDD. Our analysis represents a first step towards measuring the full atmospheric composition of these stars and learning about the bulk properties of their accreted material. As we venture into the era of wide-field spectroscopic surveys, our work highlights the importance of combining large-scale data bases for identifying and characterizing new polluted white dwarfs.
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