8,874 research outputs found
A resonant feature near the Perseus arm revealed by red clump stars
We investigate the extinction together with the radial velocity dispersion
and distribution of red clump stars in the anti-center direction using spectra
obtained with Hectospec on the MMT. We find that extinction peaks at
Galactocentric radii of about 9.5 and 12.5 kpc, right in front of the locations
of the Perseus and Outer arms and in line with the relative position of dust
and stars in external spiral galaxies. The radial velocity dispersion peaks
around 10kpc, which coincides with the location of the Perseus arm, yields an
estimated arm-interarm density contrast of 1.3-1.5 and is in agreement with
previous studies. Finally, we discover that the radial velocity distribution
bifurcates around 10-11 kpc into two peaks at +27 km/s and -4 km/s. This seems
to be naturally explained by the presence of the outer Lindblad resonance of
the Galactic bar, but further observations will be needed to understand if the
corotation resonance of the spirals arms also plays a role.Comment: 8 pages, 2 figures, accepted for publication in ApJ
Phenylboronic acid-diol crosslinked 6-<i>O</i>-vinylazeloyl-d-galactose nanocarriers for insulin delivery
A new block polymer named poly 3-acrylamidophenylboronic acid-b-6-O–vinylazeloyl-d-galactose (p(AAPBA-b-OVZG)) was prepared using 3-acrylamidophenylboronic acid (AAPBA) and 6-O-vinylazeloyl-D-galactose (OVZG) via a two-step procedure involving S-1-dodecyl-S-(α', α'-dimethyl-α″-acetic acid) trithiocarbonate (DDATC) as chain transfer agent, 2,2-azobisisobutyronitrile (AIBN) as initiator and dimethyl formamide (DMF) as solvent. The structures of the polymer were examined by Fourier transform infrared spectroscopy (FT-IR) and 1H NMR and the thermal stability was determined by thermal gravimetric analysis (TG/DTG). Transmission electron microscopy (TEM) and dynamic light scattering (DLS) were utilized to evaluate the morphology and properties of the p(AAPBA-b-OVZG) nanoparticles. The cell toxicity, animal toxicity and therapeutic efficacy were also investigated. The results indicate the p(AAPBA-b-OVZG) was successfully synthesized and had excellent thermal stability. Moreover, the p(AAPBA-b-OVZG) nanoparticles were submicron in size and glucose-sensitive in phosphate-buffered saline (PBS). In addition, insulin as a model drug had a high encapsulation efficiency and loading capacity and the release of insulin was increased at higher glucose levels. Furthermore, the nanoparticles showed a low-toxicity in cell and animal studies and they were effective at decreasing blood glucose levels of mice over 96 h. These p(AAPBA-b-OVZG) nanoparticles show promise for applications in diabetes treatment using insulin or other hypoglycemic proteins
1,1′-(2-Thienylmethylene)di-2-naphthol ethyl acetate solvate
In the title compound, C25H18O2S·C4H8O2, there are intermolecular O—H⋯O hydrogen bonds between the main molecule and the solvent molecule. The thiophene ring is oriented at dihedral angles of 70.87 (7) and 75.36 (4)° with respect to the mean planes of the two naphthyl ring systems
4-(6-Quinolyloxymethyl)benzonitrile
The title compound, C17H12N2O, was synthesized by an ether synthesis from quinolin-6-ol and 4-(bromomethyl)benzonitrile. The phenyl ring of the benzonitrile group makes a dihedral angle of 47.52 (6)° with the plane of the quinoline fragment. The crystal structure is stabilized by intermolecular C—H⋯π interactions between a benzene H atom of the benzonitrile group and the benzene ring of the quinoline fragment. In addition, the crystal structure also exhibits a weak intermolecular C—H⋯N hydrogen bond
Characterising Alzheimer's Disease with EEG-based Energy Landscape Analysis
Alzheimer's disease (AD) is one of the most common neurodegenerative
diseases, with around 50 million patients worldwide. Accessible and
non-invasive methods of diagnosing and characterising AD are therefore urgently
required. Electroencephalography (EEG) fulfils these criteria and is often used
when studying AD. Several features derived from EEG were shown to predict AD
with high accuracy, e.g. signal complexity and synchronisation. However, the
dynamics of how the brain transitions between stable states have not been
properly studied in the case of AD and EEG data. Energy landscape analysis is a
method that can be used to quantify these dynamics. This work presents the
first application of this method to both AD and EEG. Energy landscape assigns
energy value to each possible state, i.e. pattern of activations across brain
regions. The energy is inversely proportional to the probability of occurrence.
By studying the features of energy landscapes of 20 AD patients and 20 healthy
age-matched counterparts, significant differences were found. The dynamics of
AD patients' brain networks were shown to be more constrained - with more local
minima, less variation in basin size, and smaller basins. We show that energy
landscapes can predict AD with high accuracy, performing significantly better
than baseline models.Comment: 11 pages, 7 figure
Star Formation Properties in Barred Galaxies(SFB). I. Ultraviolet-to-Infrared Imaging and Spectroscopic Studies of NGC 7479
Large-scale bars and minor mergers are important drivers for the secular
evolution of galaxies. Based on ground-based optical images and spectra as well
as ultraviolet data from the Galaxy Evolution Explorer and infrared data from
the Spitzer Space Telescope, we present a multi-wavelength study of star
formation properties in the barred galaxy NGC 7479, which also has obvious
features of a minor merger. Using various tracers of star formation, we find
that under the effects of both a stellar bar and a minor merger, star formation
activity mainly takes place along the galactic bar and arms, while the star
formation rate changes from the bar to the disk. With the help of spectral
synthesis, we find that strong star formation took place in the bar region
about 100 Myr ago, and the stellar bar might have been 10 Gyr old. By
comparing our results with the secular evolutionary scenario from Jogee et al.,
we suggest that NGC 7479 is possibly in a transitional stage of secular
evolution at present, and it may eventually become an earlier type galaxy or a
luminous infrared galaxy. We also note that the probable minor merger event
happened recently in NGC 7479, and we find two candidates for minor merger
remnants.Comment: 33 pages, 10 figures, 4 tables; accepted for publication in AJ, 142,
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Phase Control on Surface for the Stabilization of High Energy Cathode Materials of Lithium Ion Batteries.
The development of high energy electrode materials for lithium ion batteries is challenged by their inherent instabilities, which become more aggravated as the energy densities continue to climb, accordingly causing increasing concerns on battery safety and reliability. Here, taking the high voltage cathode of LiNi0.5Mn1.5O4 as an example, we demonstrate a protocol to stabilize this cathode through a systematic phase modulating on its particle surface. We are able to transfer the spinel surface into a 30 nm shell composed of two functional phases including a rock-salt one and a layered one. The former is electrochemically inert for surface stabilization while the latter is designated to provide necessary electrochemical activity. The precise synthesis control enables us to tune the ratio of these two phases, and achieve an optimized balance between improved stability against structural degradation without sacrificing its capacity. This study highlights the critical importance of well-tailored surface phase property for the cathode stabilization of high energy lithium ion batteries
Association of Intrarenal B-Cell Infiltrates with Clinical Outcome in Lupus Nephritis: A Study of 192 Cases
Background. Lupus nephritis (LN) remains a major cause of morbidity and end-stage renal disease. Dysfunction of B lymphocytes is thought to be important in the pathogenesis of SLE/LN. Intrarenal B cells have been found in several forms of inflammatory kidney diseases although their role in LN renal is not well defined. Methods. Intrarenal B cells were analyzed in 192 renal biopsies from patients diagnosed with lupus nephritis. Immunohistochemical staining of serial sections was performed for each LN patient using CD20, CD3, and CD21 antibodies. Results. Intrarenal B cells were more likely to be associated with class IV LN and were mainly distributed in the renal interstitium, with very few in the glomerulus. The systemic lupus erythematosus disease activity index (SLEDAI), blood urea nitrogen, and serum creatinine levels were all significantly greater in the LN-B cell groups (all P<0.05). LN renal activity and chronicity indices correlated with B-cells infiltrates (all P<0.0001). Renal biopsies were classified into four distinct categories according to the organizational grade of inflammatory cell infiltrates. Germinal center- (GC-) like structures were not identified in any LN biopsies. Conclusion. It is hypothesized that intrarenal B cells enhance immunological responses and exaggerate the local immune response to persisting autoimmune damage in the tubulointerstitium
Fast radio bursts generated by coherent curvature radiation from compressed bunches for FRB 20190520B
The radiation mechanism of fast radio bursts (FRBs) has been extensively
studied but still remains elusive. Coherent radiation is identified as a
crucial component in the FRB mechanism, with charged bunches also playing a
significant role under specific circumstances. In the present research, we
propose a phenomenological model that draws upon the coherent curvature
radiation framework and the magnetized neutron star, taking into account the
kinetic energy losses of outflow particles due to inverse Compton scattering
(ICS) induced by soft photons within the magnetosphere. By integrating the ICS
deceleration mechanism for particles, we hypothesize a potential compression
effect on the particle number density within a magnetic tube/family, which
could facilitate achieving the necessary size for coherent radiation in the
radial direction. This mechanism might potentially enable the dynamic formation
of bunches capable of emitting coherent curvature radiation along the curved
magnetic field. Moreover, we examine the formation of bunches from an energy
perspective. Our discussion suggests that within the given parameter space the
formation of bunches is feasible. Finally, we apply this model to FRB
20190520B, one of the most active repeating FRBs discovered and monitored by
FAST. Several observed phenomena are explained, including basic
characteristics, frequency downward drifting, and bright spots within certain
dynamic spectral ranges.Comment: 16 pages, 9 figures, and 1 table. Accepted for publication in Ap
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