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8,071
result(s) for
"Liang, Qian"
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Cosmic evolution of dark energy in a generalized Rastall gravity
In this work, we propose a scheme for cosmic evolution in a generalized Rastall gravity. In our approach, the role of dark energy is taken by the non-conserved sector of the stress energy–momentum tensor. The resultant cosmic evolution is found to naturally consists of three stages, namely, radiation dominated, ordinary matter dominated, as well as dark energy and dark matter dominated eras. Furthermore, for the present model, it is demonstrated that the eventual fate of the Universe is mostly insensitive to the initial conditions, in contrast to the standard
Λ
CDM
model. In particular, the solution displays the properties of a dynamic attractor, which is reminiscent of quintessence and k-essence models. Subsequently, the cosmic coincidence problem is averted. The amount of deviation from a conserved stress energy–momentum tensor is shown to be more remarkable during the period when the dark energy evolves more rapidly. On the other hand, the conservation law is largely restored for the infinite past and future. The implications of the present approach are addressed.
Journal Article
Revealing the chirality origin and homochirality crystallization of Ag14 nanocluster at the molecular level
Although chirality is an ever-present characteristic in biology and some artificial molecules, controlling the chirality and demystifying the chirality origin of complex assemblies remain challenging. Herein, we report two homochiral Ag
14
nanoclusters with inherent chirality originated from identical rotation of six square faces on a Ag
8
cube driven by intra-cluster π···π stacking interaction between pntp
−
(Hpntp =
p-
nitrothiophenol) ligands. The spontaneous resolution of the racemic (SD/
rac
-Ag14a) to homochiral nanoclusters (SD/
L
-Ag14 and SD/
R
-Ag14) can be realized by re-crystallizing SD/
rac
-Ag14a in acetonitrile, which promotes the homochiral crystallization in solid state by forming C–H···O/N hydrogen bonds with nitro oxygen atoms in pntp
−
or aromatic hydrogen atoms in dpph (dpph = 1,6-bis(diphenylphosphino)hexane) on Ag
14
nanocluster. This work not only provides strategic guidance for the syntheses of chiral silver nanoclusters in an all-achiral environment, but also deciphers the origin of chirality at molecular level by identifying the special effects of intra- and inter-cluster supramolecular interactions.
The preparation of chiral monolayer-protected metal clusters is interesting for their potential applications in a variety of fields, including catalysis. Here, the authors synthesize chiral Ag
14
nanoclusters in an all-achiral environment, and decipher the origin of chirality at the molecular level; the solvent choice is key to achieve homochiral crystallization.
Journal Article
Ellis drainhole solution in Einstein-Æther gravity and the axial gravitational quasinormal modes
In this work, the Ellis drainhole solution is derived in Einstein-Æther gravity, and subsequently, the axial quasinormal modes of the resulting drainhole are investigated. Owing to the presence of a minimally coupled scalar field with antiorthodox coupling polarity, the resultant metric solution is featured by a throat instead of a horizon, for which static æther solution becomes feasible. Moreover, the derived master equations for the axial gravitational perturbations consist of two coupled vector degrees of freedom. By utilizing the finite difference method, the temporal profiles of the quasinormal oscillations are evaluated, and, subsequently, the complex frequencies are extracted and compared against the specific values obtained by the WKB method when the coupling is turned off. Besides, the effect of the coupling on the low-lying quasinormal spectrum is explored, and its possible physical relevance is discussed.
Journal Article
Notch Signaling Modulates Macrophage Polarization and Phagocytosis Through Direct Suppression of Signal Regulatory Protein α Expression
The Notch pathway plays critical roles in the development and functional modulation of myeloid cells. Previous studies have demonstrated that Notch activation promotes M1 polarization and phagocytosis of macrophages; however, the downstream molecular mechanisms mediating Notch signal remain elusive. In an attempt to identify Notch downstream targets in bone marrow-derived macrophages (BMDMs) using mass spectrometry, the signal regulatory protein α (SIRPα) appeared to respond to knockout of recombination signal-binding protein Jk (RBP-J), the critical transcription factor of Notch pathway, in macrophages. In this study, we validated that Notch activation could repress SIRPα expression likely
the Hes family co-repressors. SIRPα promoted macrophage M2 polarization, which was dependent on the interaction with CD47 and mediated by intracellular signaling through SHP-1. We provided evidence that Notch signal regulated macrophage polarization at least partially through SIRPα. Interestingly, Notch signal regulated macrophage phagocytosis of tumor cells through SIRPα but in a SHP-1-independent way. To access the translational value of our findings, we expressed the extracellular domains of the mouse SIRPα (mSIRPα
) to block the interaction between CD47 and SIRPα. We demonstrated that the soluble mSIRPα
polypeptides could promote M1 polarization and increase phagocytosis of tumor cells by macrophages. Taken together, our results provided new insights into the molecular mechanisms of notch-mediated macrophage polarization and further validated SIRPα as a target for tumor therapy through modulating macrophage polarization and phagocytosis.
Journal Article
Comparison of the total and hidden blood loss in patients undergoing single-level open and unilateral biportal endoscopic transforaminal lumbar interbody fusion: a retrospective case control study
Purpose
This study aimed to compare total blood loss (TBL) and hidden blood loss (HBL) in patients undergoing single-level open transforaminal lumbar interbody fusion (O-TLIF) and unilateral biportal endoscopic transforaminal lumbar interbody fusion (ULIF).
Methods
A total of 53 patients who underwent ULIF and 53 patients who underwent O-TLIF from March 2020 to July 2022 were retrospectively reviewed. The Nadler’s formula was employed to estimate the patient’s blood volume (PBV), Gross’s formula to estimate TBL, and Sehat’s formula to estimate HBL. The obtained data were then analyzed with independent t test, chi-squared test, and analysis of covariance.
Results
TBL and measured blood loss (MBL) in ULIF group (326.86 ± 223.45 ml, 99.00 ± 72.81 ml) was significantly lower than O-TLIF group (427.97 ± 280.52 ml, 270.66 ± 102.34 ml). Nevertheless, the HBL in ULIF group was higher than that in O-TLIF group (227.86 ± 221.75 ml vs 157.31 ± 268.08 ml), however this was not statistically significant (
p
= 0.143). The HBL was 69.71 ± 23.72% of TBL in ULIF group and 36.76 ± 18.79% of TBL in O-TLIF group. Patients in ULIF group had lower TBL and MBL, shorter duration of drainage, lower postoperative anemia, and shorter postoperative hospital stay compared to those in O-TLIF group.
Conclusions
Perioperative HBL should not be neglected in patients undergoing ULIF or O-TILF, as it accounts for a large percentage of TBL in both groups. ULIF is associated with lower TBL and MBL, postoperative anemia, shorter postoperative hospital stays compared with O-TLIF.
Journal Article
On the late-time tails of massive perturbations in spherically symmetric black holes
It was first pointed out by Koyama and Tomimatsu that, under reasonable assumptions, the asymptotic late-time tails of massive scalar perturbations in the far zone of spherically symmetric black hole spacetimes decay universally as t-5/6. The late-time tail is furnished by the contribution from the branch cut of the frequency-domain Green’s function, which is constructed in terms of two appropriate solutions of the corresponding homogeneous equation. The present study focuses on some particular forms of the in-going wave that were not explicitly considered in the original derivations but nonetheless have been taken into account in the literature by other authors. In this regard, we reassess the authors’ arguments and provide a detailed complimentary analysis that covers a few specific aspects. For some particular cases, the tail is found to possess the form t-1. We also discuss the possible implications of the present findings.
Journal Article
miR-148a-3p Mediates Notch Signaling to Promote the Differentiation and M1 Activation of Macrophages
The Notch pathway plays critical roles in the differentiation and polarized activation of macrophages; however, the downstream molecular mechanisms underlying Notch activity in macrophages remain elusive. Our previous study has identified a group of microRNAs that mediate Notch signaling to regulate macrophage activation and tumor-associated macrophages (TAMs). In this study, we demonstrated that miR-148a-3p functions as a novel downstream molecule of Notch signaling to promote the differentiation of monocytes into macrophages in the presence of granulocyte macrophage colony-stimulating factor (GM-CSF). Meanwhile, miR-148a-3p promoted M1 and inhibited M2 polarization of macrophages upon Notch activation. Macrophages overexpressing miR-148a-3p exhibited enhanced ability to engulf and kill bacteria, which was mediated by excessive production of reactive oxygen species (ROS). Further studies using reporter assay and Western blotting identified
as a direct target gene of miR-148a-3p in macrophages. Macrophages overexpressing miR-148a-3p increased their ROS production through the PTEN/AKT pathway, likely to defend against bacterial invasion. Moreover, miR-148a-3p also enhanced M1 macrophage polarization and pro-inflammatory responses through PTEN/AKT-mediated upregulation of NF-κB signaling. In summary, our data establish a novel molecular mechanism by which Notch signaling promotes monocyte differentiation and M1 macrophage activation through miR-148a-3p, and suggest that miR-148a-3p-modified monocytes or macrophages are potential new tools for the treatment of inflammation-related diseases.
Journal Article
Quasinormal modes in two-photon autocorrelation and the geometric-optics approximation
In this work, we study the black hole light echoes in terms of the two-photon autocorrelation and explore their connection with the quasinormal modes. It is shown that the above time-domain phenomenon can be analyzed by utilizing the well-known frequency-domain relations between the quasinormal modes and characteristic parameters of null geodesics. We found that the time-domain correlator, obtained by the inverse Fourier transform, naturally acquires the echo feature, which can be attributed to a collective effect of the asymptotic poles through a weighted summation of the squared modulus of the relevant Green’s functions. Specifically, the contour integral leads to a summation taking over both the overtone index and angular momentum. Moreover, the dominant contributions to the light echoes are from those in the eikonal limit, consistent with the existing findings using the geometric-optics arguments. For the Schwarzschild black holes, we demonstrate the results numerically by considering a transient spherical light source. Also, for the Kerr spacetimes, we point out a potential difference between the resulting light echoes using the geometric-optics approach and those obtained by the black hole perturbation theory. Possible astrophysical implications of the present study are addressed.
Journal Article
Chrysanthemum WRKY gene DgWRKY5 enhances tolerance to salt stress in transgenic chrysanthemum
WRKY transcription factors play important roles in plant growth development, resistance and substance metabolism regulation. However, the exact function of the response to salt stress in plants with specific WRKY transcription factors remains unclear. In this research, we isolated a new WRKY transcription factor
DgWRKY5
from chrysanthemum.
DgWRKY5
contains two WRKY domains of WKKYGQK and two C
2
H
2
zinc fingers. The expression of
DgWRKY5
in chrysanthemum was up-regulated under various treatments. Meanwhile, we observed higher expression levels in the leaves contrasted with other tissues. Under salt stress, the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) enzymes in transgenic chrysanthemum were significantly higher than those in WT, whereas the accumulation of H
2
O
2
, O
2
−
and malondialdehyde (MDA) was reduced in transgenic chrysanthemum. Several parameters including root length, root length, fresh weight, chlorophyll content and leaf gas exchange parameters in transgenic chrysanthemum were much better compared with WT under salt stress. Moreover, the expression of stress-related genes
DgAPX
,
DgCAT
,
DgNCED3A
,
DgNCED3B
,
DgCuZnSOD
,
DgP5CS
,
DgCSD1
and
DgCSD2
was up-regulated in
DgWRKY5
transgenic chrysanthemum compared with that in WT. These results suggested that
DgWRKY5
could function as a positive regulator of salt stress in chrysanthemum.
Journal Article