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"Dai, Hu"
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Prompt production of the hidden charm pentaquarks in the LHC
by
Pan, Ling
,
Wang, Qian
,
Xiao-Hu, Dai
in
Charm (particle physics)
,
Collaboration
,
Cross-sections
2021
Motivated by the observation of the first hidden charm pentaquarks by the LHCb collaboration in 2015 and the updated analysis with an order-of-magnitude larger data set in 2019, we estimate their cross sections for the prompt production as well as their heavy quark spin partners, in the Σc(∗)D¯(∗) hadronic molecular picture, at the center-of-mass energy 7TeV in the pp collision. Their cross sections are several nb and we would expect several tens hidden charm pentaquark events in the LHC based on its current integrated luminosity. The cross sections show a sizable deviation of the cross sections for hidden charm pentaquarks with the third isospin component Iz=+12 (Pc+) from those with Iz=-12 (Pc0). The cross sections decrease dramatically with the increasing transverse momentum. Our study can also tell where to search for the missing hidden charm pentaquarks. The confirmation of the complete hidden charm pentaquarks in the heavy quark symmetry would further verify their Σc(∗)D¯(∗) molecular interpretation. In addition, the relative strength among these cross sections for pentaquarks can help us to identify the quantum numbers of the Pc(4440) and Pc(4457).
Journal Article
MGST1 alleviates the oxidative stress of trophoblast cells induced by hypoxia/reoxygenation and promotes cell proliferation, migration, and invasion by activating the PI3K/AKT/mTOR pathway
2022
Preeclampsia (PE) is a common pregnancy-specific syndrome with an incidence of 4.6% in all pregnant women. Numerous studies have uncovered the functions and mechanisms of microsomal glutathione transferase 1 (MGST1) in different diseases and cellular processes, but whether MGST1 plays a role in PE remains unclear. Our study aimed to investigate the regulatory role of MGST1 in PE progression. In this study, the HTR8/SVneo cells were incubated with CoCl
(250 µM) to mimic hypoxia in trophoblasts. Real-time quantitative polymerase chain reaction revealed that MGST1 was dramatically reduced in the placenta of PE patients. The proliferation of HTR8/SVneo cells was assessed via the Cell Counting Kit-8 and colony formation assays, and the results showed that MGST1 upregulation increased the cell viability of HTR8/SVneo cells. In addition, wound healing and Transwell assays unveiled that the elevation of MGST1 enhanced trophoblast cell migration and invasion. Moreover, the upregulation of MGST1 alleviated the hypoxia-induced oxidative stress in trophoblast cell. Mechanically, we found that MGST1 regulated PE progression by activating the phosphoinositide-3-kinase/protein kinase B/mechanistic target of rapamycin (PI3K/AKT/mTOR) pathway. In conclusion, MGST1 alleviated the oxidative stress of trophoblast cells induced by hypoxia/reoxygenation and promoted cell proliferation, migration, and invasion via the activation of the PI3K/AKT/mTOR pathway in PE. These results suggested that MGST1 can be a potential target for the prevention and treatment of PE.
Journal Article
Hesperidin Is a Potential Inhibitor against SARS-CoV-2 Infection
by
Shen, Yi-Cheng
,
Chen, Yeh
,
Huang, Wei-Chien
in
bioavailability
,
cardioprotective effect
,
Cellular proteins
2021
Hesperidin (HD) is a common flavanone glycoside isolated from citrus fruits and possesses great potential for cardiovascular protection. Hesperetin (HT) is an aglycone metabolite of HD with high bioavailability. Through the docking simulation, HD and HT have shown their potential to bind to two cellular proteins: transmembrane serine protease 2 (TMPRSS2) and angiotensin-converting enzyme 2 (ACE2), which are required for the cellular entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Our results further found that HT and HD suppressed the infection of VeroE6 cells using lentiviral-based pseudo-particles with wild types and variants of SARS-CoV-2 with spike (S) proteins, by blocking the interaction between the S protein and cellular receptor ACE2 and reducing ACE2 and TMPRSS2 expression. In summary, hesperidin is a potential TMPRSS2 inhibitor for the reduction of the SARS-CoV-2 infection.
Journal Article
Impact of Spectral Resolution and Signal-to-Noise Ratio in Vis–NIR Spectrometry on Soil Organic Matter Estimation
2023
Recently, considerable efforts have been devoted to the estimation of soil properties using optical payloads mounted on drones or satellites. Nevertheless, many studies focus on diverse pretreatments and modeling techniques, while there continues to be a conspicuous absence of research examining the impact of parameters related to optical remote sensing payloads on predictive performance. The main aim of this study is to evaluate how the spectral resolution and signal-to-noise ratio (SNR) of spectrometers affect the precision of predictions for soil organic matter (SOM) content. For this purpose, the initial soil spectral library was partitioned into to two simulated soil spectral libraries, each of which were individually adjusted with respect to the spectral resolutions and SNR levels. To verify the consistency and generality of our results, we employed four multiple regression models to develop multivariate calibration models. Subsequently, in order to determine the minimum spectral resolution and SNR level without significantly affecting the prediction accuracy, we conducted ANOVA tests on the RMSE and R2 obtained from the independent validation dataset. Our results revealed that (i) the factors significantly affecting SOM prediction performance, in descending order of magnitude, were the SNR levels > spectral resolutions > estimation models, (ii) no substantial difference existed in predictive performance when the spectral resolution fell within 100 nm, and (iii) when the SNR levels exceeded 15%, altering them did not notably affect the SOM predictive performance. This study is expected to provide valuable insights for the design of future optical remote sensing payloads aimed at monitoring large-scale SOM dynamics.
Journal Article
Cigarette smoke-induced LKB1/AMPK pathway deficiency reduces EGFR TKI sensitivity in NSCLC
2021
Smoker patients with non-small cell lung cancer (NSCLC) have poorer prognosis and survival than those without smoking history. However, the mechanisms underlying the low response rate of those patients to EGFR tyrosine kinase inhibitors (TKIs) are not well understood. Here we report that exposure to cigarette smoke extract enhances glycolysis and attenuates AMP-activated protein kinase (AMPK)-dependent inhibition of mTOR; this in turn reduces the sensitivity of NSCLC cells with wild-type EGFR (EGFR
WT
) to EGFR TKI by repressing expression of liver kinase B1 (LKB1), a master kinase of the AMPK subfamily, via CpG island methylation. In addition, LKB1 expression is correlated positively with sensitivity to TKI in patients with NSCLC. Moreover, combined treatment of EGFR TKI with AMPK activators synergistically increases EGFR TKI sensitivity. Collectively, the current study suggests that LKB1 may serve as a marker to predict EGFR TKI sensitivity in smokers with NSCLC carrying EGFR
WT
and that the combination of EGFR TKI and AMPK activator may be a potentially effective therapeutic strategy against NSCLC with EGFR
WT
.
Journal Article
Dynamic pitching of an elastic rectangular wing in hovering motion
by
Dai, Hu
,
Luo, Haoxiang
,
Doyle, James F.
in
Aerodynamics
,
Applied fluid mechanics
,
Biochemistry. Physiology. Immunology
2012
In order to study the role of the passive deformation in the aerodynamics of insect wings, we computationally model the three-dimensional fluid–structure interaction of an elastic rectangular wing at a low aspect ratio during hovering flight. The code couples a viscous incompressible flow solver based on the immersed-boundary method and a nonlinear finite-element solver for thin-walled structures. During a flapping stroke, the wing surface is dominated by non-uniform chordwise deformations. The effects of the wing stiffness, mass ratio, phase angle of active pitching, and Reynolds number are investigated. The results show that both the phase and the rate of passive pitching due to the wing flexibility can significantly modify the aerodynamics of the wing. The dynamic pitching depends not only on the specified kinematics at the wing root and the stiffness of the wing, but also greatly on the mass ratio, which represents the relative importance of the wing inertia and aerodynamic forces in the wing deformation. We use the ratio between the flapping frequency, $\\omega $, and natural frequency of the wing, ${\\omega }_{n} $, as the non-dimensional stiffness. In general, when $\\omega / {\\omega }_{n} \\leq 0. 3$, the deformation significantly enhances the lift and also improves the lift efficiency despite a disadvantageous camber. In particular, when the inertial pitching torque is assisted by an aerodynamic torque of comparable magnitude, the lift efficiency can be markedly improved.
Journal Article
Study on the flow field and structural stress field of the primary retarder considering the throttling characteristics of the valve
2025
The valve plays an important role in the control of the filling rate (qfill) and braking characteristics of the hydrodynamic retarder (HR). However, the dynamic throttling characteristics of the valve were rarely considered in previous studies. Therefore, this paper considers the influence of the external valve system (retarder valve) of HR on its flow field, structural field and braking characteristics. Firstly, numerical calculation and experimental verification are carried out on the flow passage model without inlet and outlet (Plan A), with inlet and outlet (Plan B) and with retarder valve (Plan C). After considering the throttling characteristics of the retarder valve, the maximum errors of the impeller rotational speed (n), qfill and braking torque (T) characteristic curves are 2.678% and 3.517%, respectively, and the average errors are 4.526% and 5.012%, respectively. Compared with the other two schemes, the average error and maximum error of HR have been greatly reduced. Then, this paper compares the differences between the three schemes from the perspective of flow field and structural field, and expounds the influence of retarder valve on the numerical calculation results of retarder from the internal mechanism. Finally, this paper discusses the influence of n, qfill and retarder valve opening on the calculation results of Scheme C. The results show that the opening of the valve port will seriously affect the flow rate at the inlet of HR, and the flow rate in the retarder valve will have a hysteresis effect on the circulation flow in the mainstream region of HR. The research method of this paper can provide reference for the numerical study of turbomachinery.
Journal Article
Nonlinear oscillations of a dielectric elastomer membrane subjected to in-plane stretching
2015
An analytical model is proposed for the dynamic behavior analysis of a dielectric elastomer (DE) membrane undergoing in-plane stretching. We employ the neo-Hookean model for describing the hyperelasticity feature of the DE membrane. The DE membrane is assumed to elongate only in length direction. For better understanding the dynamic responses of the DE membrane, both free and forced oscillations of the nonlinear system are analyzed. The results show that the system may display periodic oscillations in its length, no matter the DE membrane is constrained by linear or nonlinear cubic springs. It is found that quasi-periodic oscillations of the DE membrane fairly occur provided an in-plane harmonic force is applied. In addition, the response frequencies of the system are also addressed.
Journal Article
COX-3, a Cyclooxygenase-1 Variant Inhibited by Acetaminophen and Other Analgesic/Antipyretic Drugs: Cloning, Structure, and Expression
by
Dai, Hu
,
K. Lamar Turepu Roos
,
Elton, Terry S.
in
Acetaminophen - pharmacology
,
Analgesics
,
Analgesics, Non-Narcotic - pharmacology
2002
Two cyclooxygenase isozymes, COX-1 and -2, are known to catalyze the rate-limiting step of prostaglandin synthesis and are the targets of nonsteroidal antiinflammatory drugs. Here we describe a third distinct COX isozyme, COX-3, as well as two smaller COX-1-derived proteins (partial COX-1 or PCOX-1 proteins). COX-3 and one of the PCOX-1 proteins (PCOX-1a) are made from the COX-1 gene but retain intron 1 in their mRNAs. PCOX-1 proteins additionally contain an in-frame deletion of exons 5-8 of the COX-1 mRNA. COX-3 and PCOX mRNAs are expressed in canine cerebral cortex and in lesser amounts in other tissues analyzed. In human, COX-3 mRNA is expressed as an ≈5.2-kb transcript and is most abundant in cerebral cortex and heart. Intron 1 is conserved in length and in sequence in mammalian COX-1 genes. This intron contains an ORF that introduces an insertion of 30-34 aa, depending on the mammalian species, into the hydrophobic signal peptide that directs COX-1 into the lumen of the endoplasmic reticulum and nuclear envelope. COX-3 and PCOX-1a are expressed efficiently in insect cells as membrane-bound proteins. The signal peptide is not cleaved from either protein and both proteins are glycosylated. COX-3, but not PCOX-1a, possesses glycosylation-dependent cyclooxygenase activity. Comparison of canine COX-3 activity with murine COX-1 and -2 demonstrates that this enzyme is selectively inhibited by analgesic/antipyretic drugs such as acetaminophen, phenacetin, antipyrine, and dipyrone, and is potently inhibited by some nonsteroidal antiinflammatory drugs. Thus, inhibition of COX-3 could represent a primary central mechanism by which these drugs decrease pain and possibly fever.
Journal Article
Auxiliary Decision-Making System for Steel Plate Cold Straightening Based on Multi-Machine Learning Competition Strategies
2022
In the process of steel plate production, whether cold straightening is required is significant to reduce costs and improve product qualification rates. It is not effective by adopting classic machine learning judgment algorithms. Concerning the effectiveness of ensemble learning methods on improving traditional machine learning methods, a steel plate cold straightening auxiliary decision-making algorithm based on multiple machine learning competition strategies is proposed in this paper. The algorithm firstly adopts the rough set method to simplify the attributes of the conditional factors for affecting whether the steel plate cold straightening is required, and reduce the attribute dimensions of the steel plate cold straightening auxiliary decision-making data set. Secondly, the competition of training multiple different learners on the data set produces the optimal base classifier. Finally, the final classifier is generated by training weights on the optimal base classifier and combining it with a centralized strategy. While the hit rate of good products of the final classifier is 97.9%, the hit rate of defective products is 90.9%. As such, the accuracy rate is better than the single kind of simple machine learning algorithms, which effectively improves the product quality of steel plates in practical production applications.
Journal Article