30 research outputs found
Observation of GRB 221009A early afterglow in X/-ray energy band
The early afterglow of a Gamma-ray burst (GRB) can provide critical
information on the jet and progenitor of the GRB. The extreme brightness of GRB
221009A allows us to probe its early afterglow in unprecedented detail. In this
letter, we report comprehensive observation results of the early afterglow of
GRB 221009A (from +660 s to +1860 s, where is the
\textit{Insight}-HXMT/HE trigger time) in X/-ray energy band (from 20
keV to 20 MeV) by \textit{Insight}-HXMT/HE, GECAM-C and \textit{Fermi}/GBM. We
find that the spectrum of the early afterglow in 20 keV-20 MeV could be well
described by a cutoff power-law with an extra power-law which dominates the low
and high energy bands respectively. The cutoff power-law is
30 keV and the power-law photon index is 1.8 throughout the early
afterglow phase. By fitting the light curves in different energy bands, we find
that a significant achromatic break (from keV to TeV) is required at +
1246 s (i.e. 1021 s since the afterglow starting time =+225 s), providing compelling evidence of a jet break. Interestingly,
both the pre-break and post-break decay slopes vary with energy, and these two
slopes become closer in the lower energy band, making the break less
identifiable. Intriguingly, the spectrum of the early afterglow experienced a
slight hardening before the break and a softening after the break. These
results provide new insights into the understanding of this remarkable GRB.Comment: Accepted for publication in ApJ Letters on 19-Jan-2024, 11 pages, 7
figures and 2 table
Tissue microarray analysis reveals a tight correlation between protein expression pattern and progression of esophageal squamous cell carcinoma
BACKGROUND: The development of esophageal squamous cell carcinoma (ESCC) progresses a multistage process, collectively known as precursor lesions, also called dysplasia (DYS) and carcinoma in situ (CIS), subsequent invasive lesions and final metastasis. In this study, we are interested in investigating the expression of a variety of functional classes of proteins in ESCC and its precursor lesions and characterizing the correlation of these proteins with ESCC malignant progression. METHODS: Fas, FADD, caspase 8, CDC25B, fascin, CK14, CK4, annexin I, laminin-5γ2 and SPARC were analyzed using immunohistochemistry on tissue microarray containing 205 ESCC and 173 adjacent precursor lesions as well as corresponding normal mucosa. To confirm the immunohistochemical results, three proteins, fascin, CK14 and laminin-5γ2, which were overexpressed in ESCC on tissue microarray, were detected in 12 ESCC cell lines by Western blot assay. RESULTS: In ESCC and its precursor lesions, FADD, CDC25B, fascin, CK14, laminin-5γ2 and SPARC were overexpressed, while Fas, caspase 8, CK4 and annexin I were underexpressed. The abnormalities of these proteins could be classified into different groups in relation to the stages of ESCC development. They were "early" corresponding to mild and moderate DYS with overexpression of fascin, FADD and CDC25B and underexpression of Fas, caspase 8, CK4 and annexin I, "intermediate" to severe DYS and CIS with overexpression of FADD and CK14, and "late" to invasive lesions (ESCC) and to advanced pTNM stage ESCC lesions with overexpression of CK14, laminin-5γ2 and SPARC. CONCLUSION: Analyzing the protein expression patterns of Fas, FADD, caspase 8, CDC25B, fascin, CK14, CK4, annexin I, laminin-5γ2 and SPARC would be valuable to develop rational strategies for early detection of lesions at risk in advance as well as for prevention and treatment of ESCC
Isothermal diffusion behavior and surface performance of Cu/Ni coating on TC4 alloy
The poor surface performance of titanium alloys substantially limits their application in many fields, such as the petrochemical industry. To overcome this weakness, the Cu and Ni double layers were deposited on the surface of TC4 alloy by the electroplating method, and the isothermal diffusion process was performed at 700 °C to enhance the binding ability between Cu and Ni layers. The isothermal diffusion behavior and microstructure of the coating were systematically analyzed, and tribological property and corrosion resistance of the coating were also evaluated to reveal the influence of isothermal diffusion on the surface performance. It was shown that multiple diffusion layers appeared on the Cu/Ni and Ni/Ti interface, and that NixTiy and CuxTiy phases were formed in the coating with the increase of diffusion time. More importantly, Kirkendall diffusion occurred when the diffusion time increased, which led to the formation of continuous microvoids and cracks in the diffusion layer, weakening the surface performance of the Cu/Ni coatings. This paper unveils the relationship between the microstructure of the Cu/Ni coatings and isothermal diffusion behavior, providing guidelines in preparing high performance surface coatings.</p
The 2018 Outburst of MAXI J1820+070 as Seen by Insight-HXMT
We present an analysis of the whole 2018 outburst of the black hole X-ray binary MAXI J1820+070 with Insight-HXMT data. We focus our study on the temporal evolution of the parameters of the source. We employ two different models to fit the disk’s thermal spectrum: the Newtonian model diskbb and the relativistic model nkbb . These two models provide different pictures of the source in the soft state. With diskbb , we find that the inner edge of the disk is close to the innermost stable circular orbit of a fast-rotating black hole and the corona changes geometry from the hard to the soft state. With nkbb , we find that the disk is truncated in the soft state and that the coronal geometry does not change significantly during the whole outburst. However, the model with nkbb can predict an untruncated disk around a fast-rotating black hole if we assume that the disk inclination angle is around 30° (instead of ∼60°, which is the inclination angle of the jet and is usually adopted as the disk inclination angle in the literature) and we employ a high-density reflection model. In such a case, we measure a high value of the black hole spin parameter with observations in the soft state, in agreement with the high spin value found from the analysis of the reflection features and in disagreement with the low spin value found by previous continuum-fitting method measurements with the disk inclination angle set to the value of the jet inclination angle
Bioactive Octahydroxylated C<sub>21</sub> Steroids from the Root Bark of Lycium chinense
Lyciumsterols A–K (<b>1</b>–<b>11</b>), 11 new octahydroxylated C<sub>21</sub> steroids,
were isolated
from the root bark of Lycium chinense, along with 15 known compounds. Characterization of these C<sub>21</sub> steroids showed the presence of eight hydroxy groups on
the C<sub>21</sub> steroid skeleton with a (2<i>E</i>,4<i>E</i>)-5-phenyl-2,4-pentadienoate group at C-12 or C-20 and
various 2,6-deoxy sugar residues at C-3. The structures of these compounds
were elucidated using spectroscopic data interpretation. Compounds <b>2</b>, <b>3</b>, and <b>7</b> exhibited dose-dependent
protective effects on pancreatic islet cells and may help to improve
cell viability. In addition, it was found that compounds <b>7</b>, <b>8</b>, <b>9</b>, and <b>11</b> exhibited autophagy
activation