9 research outputs found
IC 225: a dwarf elliptical galaxy with a peculiar blue core
We present the discovery of a peculiar blue core in the elliptical galaxy IC
225 by using images and spectrum from the Sloan Digital Sky Survey (SDSS). The
outer parts of the surface brightness profiles of u-, g-, r-, i- and z-band
SDSS images for IC 225 are well fitted with an exponential function. The
fitting results show that IC 225 follows the same relations between the
magnitude, scale length and central surface brightness for dwarf elliptical
galaxies. Its absolute blue magnitude (M_B) is -17.14 mag, all of which suggest
that IC 225 is a typical dwarf elliptical galaxy. The g-r color profile
indicates a very blue core with a radius of 2 arcseconds, which is also clearly
seen in the RGB image made of g-, r- and i-band SDSS images. The SDSS optical
spectrum exhibits strong and very narrow nebular emission lines. The metal
abundances derived by the standard methods, which are 12+log(O/H) = 8.98,
log(N/O) = -0.77 and 12+log(S+/H+) = 6.76, turn out to be significantly higher
than that predicted by the well-known luminosity-metallicity relation. After
carefully inspecting the central region of IC 225, we find that there are two
distinct nuclei, separated by 1.4 arcseconds, the off-nucleated one is even
bluer than the nucleus of IC 225. The asymmetric line profiles of higher-order
Balmer lines indicate that the emission lines are bluer shifted relative to the
absorption lines, suggesting that the line emission arises from the off-center
core, whose nature is a metal-rich Hii region. To the best of our knowledge, it
is the first high-metallicity Hii region detected in a dwarf elliptical galaxy.Comment: 7 figures, accepted for publication in A
Case report: Optical genome mapping revealed double rearrangements in a male undergoing preimplantation genetic testing
Chromosome rearrangement is one of the main causes of abortion. In individuals with double chromosomal rearrangements, the abortion rate and the risk of producing abnormal chromosomal embryos are increased. In our study, preimplantation genetic testing for structural rearrangement (PGT-SR) was performed for a couple because of recurrent abortion and the karyotype of the male was 45, XY der (14; 15)(q10; q10). The PGT-SR result of the embryo in this in vitro fertilization (IVF) cycle showed microduplication and microdeletion at the terminals of chromosomes 3 and 11, respectively. Therefore, we speculated whether the couple might have a cryptic reciprocal translocation which was not detected by karyotyping. Then, optical genome mapping (OGM) was performed for this couple, and cryptic balanced chromosomal rearrangements were detected in the male. The OGM data were consistent with our hypothesis according to previous PGT results. Subsequently, this result was verified by fluorescence in situ hybridization (FISH) in metaphase. In conclusion, the male’s karyotype was 45, XY, t(3; 11)(q28; p15.4), der(14; 15)(q10; q10). Compared with traditional karyotyping, chromosomal microarray, CNV-seq and FISH, OGM has significant advantages in detecting cryptic and balanced chromosomal rearrangements
Strong Solvent and Dual Lithium Salts Enable Fast-Charging Lithium-Ion Batteries Operating from −78 to 60 °C
Current
lithium-ion batteries degrade under high rates and low
temperatures due to the use of carbonate electrolytes with restricted
Li+ conduction and sluggish Li+ desolvation.
Herein, a strong solvent with dual lithium salts surmounts the thermodynamic
limitations by regulating interactions among Li+ ions,
anions, and solvents at the molecular level. Highly dissociated lithium
bis(fluorosulfonyl)imide (LiFSI) in dimethyl sulfite (DMS) solvent
with a favorable dielectric constant and melting point ensures rapid
Li+ conduction while the high affinity between difluoro(oxalato)borate
anions (DFOB–) and Li+ ions guarantees
smooth Li+ desolvation within a wide temperature range.
In the meantime, the ultrathin self-limited electrode/electrolyte
interface and the electric double layer induced by DFOB– result in enhanced electrode compatibility. The as-formulated electrolyte
enables stable cycles at high currents (41.3 mA cm–2) and a wide temperature range from −78 to 60 °C. The
1 Ah graphite||LiCoO2 (2 mAh cm–2) pouch
cell achieves 80% reversible capacity at 2 C rate under −20
°C and 86% reversible capacity at 0.1 C rate under −50
°C. This work sheds new light on the electrolyte design with
strong solvent and dual lithium salts and further facilitates the
development of high-performance lithium-ion batteries operating under
extreme conditions