69 research outputs found
Dimethyl(2-oxo-2-phenylethyl)sulfanium bromide
Single crystals of the title compound, C10H13OS+·Br−, were obtained from ethyl acetate/ethyl ether after reaction of acetophenone with hydrobromic acid and dimethylsulfoxide. The carbonyl group is almost coplanar with the neighbouring phenyl ring [O—C—C—C = 178.9 (2)°]. The sulfanium group shows a trigonal–pyramidal geometry at the S atom. The crystal structure is stabilized by C—H⋯Br hydrogen-bonding interactions. Weak π–π interactions link adjacent phenyl rings [centroid–centroid distance = 3.946 (2) Å]
2,5-Bis[(3-hydroxypropyl)amino]-1,4-benzoquinone monohydrate
The title compound, C12H18N2O4·H2O, was obtained as a product of the reaction of hydroquinone with n-propanol amine. The compound crystallizes as a monohydrate, integrating water into its hydrogen-bonded network. Each diaminoquinone moiety forms two centrosymmetric 10-membered rings through C=O⋯H—N bonds. The resulting bands along [102] are interlinked through hydroxy groups and water molecules into three-dimensional network. The chemically equivalent bond lengths in the diaminoquinone moiety exhibit a perceptible discrepancy [e.g. C=O bond lengths differ by 0.016 (2) Å], apparently as a result of asymmetric hydrogen bonding: one O atom serves as an acceptor of one hydrogen bond, whereas the other is an acceptor of two
Activation of the IL-23/Th17 Axis
The aim of this paper is to determine the modulatory effects of Lactobacillus acidophilus on the IL-23/Th17 immune axis in experimental colitis. DSS-induced mouse models of UC were to be saline, hormones, and different concentrations of Lactobacillus acidophilus intervention. The expression of interleukin-(IL-) 17, tumor necrosis factor (TNF ), IL-23, transforming growth factor 1 (TGF 1), signal transducer and activator of transcription 3 (STAT3), and phosphorylated (p)-STAT3 was examined by RT-PCR, Western blotting, and immunohistochemical analysis. And the results showed that administration of L. acidophilus suppressed Th17 cell-mediated secretion of proinflammatory cytokine IL-17 through downregulation of IL-23 and TGF 1 expression and downstream phosphorylation of p-STAT3
Searching for axion dark matter with MeerKAT Radio Telescope
Axions provide a natural and well-motivated dark matter candidate, with the
capability to convert directly to photons in the presence of an electromagnetic
field. A particularly compelling observational target is the conversion of dark
matter axions into photons in the magnetospheres of highly magnetised neutron
stars, which is expected to produce a narrow spectral peak centred at the
frequency of the axion mass. We point the MeerKAT radio telescope towards the
isolated neutron star J0806.44123 for -hours of observation and obtain
the radio spectra in the frequency range - MHz. By modelling the
conversion process of infalling axion dark matter (DM), we then compare these
spectra to theoretical expectations for a given choice of axion parameters.
Whilst finding no signal above in the data, we provide a unique
constraint on the Primakoff coupling of axion DM, at the
confidence level, in the mass range -eV. This result serves
the strongest constraint in the axion mass range -eV.Comment: 6 pages, 3 figures, accepted by Physical Review
Decrease in the production of beta-amyloid by berberine inhibition of the expression of beta-secretase in HEK293 cells
<p>Abstract</p> <p>Background</p> <p>Berberine (BER), the major alkaloidal component of <it>Rhizoma coptidis</it>, has multiple pharmacological effects including inhibition of acetylcholinesterase, reduction of cholesterol and glucose levels, anti-inflammatory, neuroprotective and neurotrophic effects. It has also been demonstrated that BER can reduce the production of beta-amyloid<sub>40/42</sub>, which plays a critical and primary role in the pathogenesis of Alzheimer's disease. However, the mechanism by which it accomplishes this remains unclear.</p> <p>Results</p> <p>Here, we report that BER could not only significantly decrease the production of beta-amyloid<sub>40/42 </sub>and the expression of beta-secretase (BACE), but was also able to activate the extracellular signal-regulated kinase1/2 (ERK1/2) pathway in a dose- and time-dependent manner in HEK293 cells stably transfected with APP695 containing the Swedish mutation. We also find that U0126, an antagonist of the ERK1/2 pathway, could abolish (1) the activation activity of BER on the ERK1/2 pathway and (2) the inhibition activity of BER on the production of beta-amyloid<sub>40/42 </sub>and the expression of BACE.</p> <p>Conclusion</p> <p>Our data indicate that BER decreases the production of beta-amyloid<sub>40/42 </sub>by inhibiting the expression of BACE via activation of the ERK1/2 pathway.</p
Spatial Analyses and Susceptibility Modeling of Thermokarst Lakes in Permafrost Landscapes along the Qinghai–Tibet Engineering Corridor
Thermokarst lakes (TLs) caused by the thaw of massive ground ice in ice-rich permafrost landscapes are increasing and have strong impacts on the hydro–ecological environment and human infrastructure on the Qinghai–Tibet Plateau (QTP), however, its spatial distribution characteristics and environmental controls have not been underrepresented at the local scale. Here, we analyzed the spatial distribution of small TLs along the Qinghai–Tibet Engineering Corridor (QTEC) based on high-resolution (up to 2.0 m) satellite images. The TLs gathered in the plains and upland plateau and covered 8.3% of the QTEC land. We deployed a random-frost method to investigate the suitable environmental conditions for TLs. Climate including summer rainfall and the air temperature was the most important factor controlling the TL distribution, followed by topography and soil characteristics that affected the ground ice content. TL susceptibility was mapped based on the combinations of climate, soil, and topography grid data. On average, around 20% of the QTEC area was in a high to very-high-susceptibility zone that is likely to develop TLs in response to climate change. This study improved the understanding of controlling factors for TL development but also provided insights into the conditions of massive ground ice and was helpful to assess the impacts of climate change on ecosystem processes and engineering design
Novel Special Orthogonal Group Optimization for Coarse Alignment Method of SINS on a Rocking Base
In order to solve the coarse alignment problem of the strapdown inertial navigation system on a rocking base, a fast coarse alignment method using the Special Orthogonal Group optimization has been proposed in this paper. In this method, based on the alignment idea of tracing gravitational apparent motion in inertial frame, the model of coarse alignment on a rocking base has been established using the Special Orthogonal Group directly. A new attitude error function has been proposed on the basis of the cosines between the measurement vector and predictive vector to describe the error between the estimated attitude and the true one. In order to directly reflect the change in the attitude error in the new innovation term and enable the attitude error to converge to zero as fast as possible, the gradient of the new attitude error function has been selected as the new innovation term to compensate for the attitude in the estimation process. Finally, the stability of the proposed optimization estimation method has been proved by employing the Lyapunov stability theory. Simulation and experiment results show that the method presented in this paper exhibits good performance in terms of alignment accuracy and time and can be applied to coarse alignment under a rocking base under different environments
High Spatial Resolution Modeling of Climate Change Impacts on Permafrost Thermal Conditions for the Beiluhe Basin, Qinghai-Tibet Plateau
Permafrost is degrading on the Qinghai-Tibet Plateau (QTP) due to climate change. Permafrost degradation can result in ecosystem changes and damage to infrastructure. However, we lack baseline data related to permafrost thermal dynamics at a local scale. Here, we model climate change impacts on permafrost from 1986 to 2075 at a high resolution using a numerical model for the Beiluhe basin, which includes representative permafrost environments of the QTP. Ground surface temperatures are derived from air temperature using an n-factor vs Normalized Differential Vegetation Index (NDVI) relationship. Soil properties are defined by field measurements and ecosystem types. The climate projections are based on long-term observations. The modelled ground temperature (MAGT) and active-layer thickness (ALT) are close to in situ observations. The results show a discontinuous permafrost distribution (61.4%) in the Beiluhe basin at present. For the past 30 years, the permafrost area has decreased rapidly, by a total of 26%. The mean ALT has increased by 0.46 m. For the next 60 years, 8.5−35% of the permafrost area is likely to degrade under different trends of climate warming. The ALT will probably increase by 0.38−0.86 m. The results of this study are useful for developing a deeper understanding of ecosystem change, permafrost development, and infrastructure development on the QTP
Point-Wise Phase Estimation Method in Fringe Projection Profilometry under Non-Sinusoidal Distortion
In fringe projection profilometry, high-order harmonics information of distorted fringe will lead to errors in the phase estimation. In order to solve this problem, a point-wise phase estimation method based on a neural network (PWPE-NN) is proposed in this paper. The complex nonlinear mapping relationship between the gray values and the phase under non-sinusoidal distortion is constructed by using the simple neural network model. It establishes a novel implicit expression for phase solution without complicated measurement operations. Compared with the previous method of combining local image information, it can accurately calculate each phase value by point. The comparison results show that the traditional method is with periodic phase errors, while the proposed method can effectively eliminate phase errors caused by non-sinusoidal phase shifting
Customizing Governance Mechanisms To Reduce Opportunism In Buyer-Supplier Relationships In the Digital Economy
Digitalization benefits supply chains but also creates new challenges for buyer–supplier relationship governance. An imbalance of digitalization between exchange partners increases dependence, information asymmetry, and data leakage, which can result in a high risk of opportunism for the less digitalized firm. However, few studies have examined how to handle this opportunism in today\u27s digital economy. Adopting a transaction cost economics perspective, we examined the customization of combinations of traditional governance instruments, including contracts, monitoring, communication, and relational norms, to efficiently combat opportunism. Applying fuzzy-set qualitative comparative analysis (fsQCA) to data collected from 137 manufacturing firms, we identified five customized combinations of various governance mechanisms that effectively reduce opportunism between supply chain partners. However, transactional mechanisms alone offer the best empirical explanation for lowering perceived opportunism than a combination of relational and transactional mechanisms. This study contributes to the literature on supply chain relationship management in the digital economy and provides practical guidance to help firms establish an appropriate governance structure to mitigate opportunism
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