112 research outputs found
Bexarotene enhances heart structure and function in diabetic rats by inhibiting ventricular remodeling and cardiomyocyte apoptosis
Purpose: To investigate the influence of bexarotene (Bex) on cardiac structure and function in streptozotocin (STZ)-induced diabetes mellitus (DM) rats, and the mechanism of action involved.
Methods: Four groups of Sprague Dawley rats (n = 40) were used: normal control, DM, DM+ Bex (10 mg/kg/day), and DM+ Bex (20 mg/kg/day) (n = 10). The DM rat model was established by intraperitoneal injection of STZ. Cardiac structure and function of rats were determined and compared. Whole heart and left ventricle were weighed. The protein expressions of Bcl2 and Bax in rat myocardial tissue were determined using Western blotting.
Results: Compared to control group, there was significant reduction in the levels of IVSd (inlet ventricular septal defect) and LVPWd (left ventricle posterior wall in diastole) in DM group, but significant increase in these parameters in DM +Bex (20 mg/kg/day) group, relative to DM-treated rats (p < 0.05). Moreover, there were higher expression levels of Bcl2 and Bax in DM group, when compared with normal control, but Bcl2/Bax ratio was significantly lower (p < 0.05). Furthermore, Bcl2 and Bax levels in DM + Bex (20 mg/kg/day) group were significantly lower than those in DM group, while Bcl2/Bax ratio increased significantly (p < 0.05).
Conclusion: Bexarotene improves the cardiac structure of DM rats by lowering blood glucose, and by inhibiting ventricular remodeling and cardiomyocyte apoptosis. These findings may be beneficial in the development of new anti-DM drugs
On the measurement of surface diffusivity in disordered nanoporous carbon via molecular dynamics simulations
Gas diffusion in nanoporous carbon includes distinct diffusion modes: surface diffusion on the pore walls and non-surface diffusion away from pore walls. We have performed molecular dynamics (MD) simulations of Ar diffusion in disordered nanoporous carbon. The main objective of this work is to separate the surface diffusion and non-surface diffusion contributions so as to comprehend their respective dependency on the porous structure and testing conditions. The nanoporous carbon sample is obtained using the quenched molecular dynamics (QMD) method. Gas flows are generated by applying a constant external force on each Ar atom, mimicking a constant chemical potential gradient. The contributions from surface diffusion and non-surface diffusion are separated according to the distance of the gas atoms away from the pore wall. We show that the surface diffusivity is affected by the interactions between gas atoms and the pore walls, the temperature, and the loading
Triplet Attention Transformer for Spatiotemporal Predictive Learning
Spatiotemporal predictive learning offers a self-supervised learning paradigm
that enables models to learn both spatial and temporal patterns by predicting
future sequences based on historical sequences. Mainstream methods are
dominated by recurrent units, yet they are limited by their lack of
parallelization and often underperform in real-world scenarios. To improve
prediction quality while maintaining computational efficiency, we propose an
innovative triplet attention transformer designed to capture both inter-frame
dynamics and intra-frame static features. Specifically, the model incorporates
the Triplet Attention Module (TAM), which replaces traditional recurrent units
by exploring self-attention mechanisms in temporal, spatial, and channel
dimensions. In this configuration: (i) temporal tokens contain abstract
representations of inter-frame, facilitating the capture of inherent temporal
dependencies; (ii) spatial and channel attention combine to refine the
intra-frame representation by performing fine-grained interactions across
spatial and channel dimensions. Alternating temporal, spatial, and
channel-level attention allows our approach to learn more complex short- and
long-range spatiotemporal dependencies. Extensive experiments demonstrate
performance surpassing existing recurrent-based and recurrent-free methods,
achieving state-of-the-art under multi-scenario examination including moving
object trajectory prediction, traffic flow prediction, driving scene
prediction, and human motion capture.Comment: Accepted to WACV 202
Effect of berbamine hydrochloride on the absorption of berberine hydrochloride in an in situ single-pass intestinal perfusion system in rats
Purpose: To investigate the intestinal absorption characteristics of berberine hydrochloride (BBH) under different perfusion conditions in rats.Methods: Based on the in situ single-pass intestinal perfusion model of rats, HPLC was used to determine the content of berberine hydrochloride in solution after perfusion under different conditions. The absorption rate constant (Ka), effective permeability coefficient (Papp) and cumulative absorption per unit area (Q) under different perfusion conditions were analyzed by one-way ANOVA.Results: The Papp and Ka of BBH in perfusion solution at pH 7.4 were greater than those in perfusion solution at pH 6 and 8. There was no significant difference (p > 0.05) in Papp and Ka of duodenum, jejunum and ileum at high, medium and low concentrations of berberine hydrochloride perfusion solution. The Q increased linearly with increase of mass concentration of perfusion solution. The Ka and Papp of BBH in duodenum, jejunum, and ileum of BBH and berbamine hydrochloride (BAH) combined at different ratios were higher than those of BBH control group at the same BBH concentration, but absorption of BBH in the ratio B40:A50 and B30:A20 groups was highest. In the ratio of B40:A50 ratio, B30:A20 ratio group or the same concentration's BBH group, Ka and Papp of BBH decreased in the order of jejunum > duodenum > ileum.Conclusion: Berberine hydrochloride is absorbed in neutral environment of pH 7.4. The intestinal absorption mechanism of BBH is passive diffusion, and jejunum is the best intestinal segment for absorption. BAH promotes the absorption of BBH
Downramp-assisted underdense photocathode electron bunch generation in plasma wakefield accelerators
It is shown that the requirements for high quality electron bunch generation
and trapping from an underdense photocathode in plasma wakefield accelerators
can be substantially relaxed through localizing it on a plasma density
downramp. This depresses the phase velocity of the accelerating electric field
until the generated electrons are in phase, allowing for trapping in shallow
trapping potentials. As a consequence the underdense photocathode technique is
applicable by a much larger number of accelerator facilities. Furthermore, dark
current generation is effectively suppressed.Comment: 4 pages, 3 figure
Efficient expression and characterization of a cold-active endo-1, 4-\u3b2-glucanase from Citrobacter farmeri by co-expression of Myxococcus xanthus protein S
Background: Cold-active endo-1, 4-\u3b2-glucanase (EglC) can decrease
energy costs and prevent product denaturation in biotechnological
processes. However, the nature EglC from C. farmeri A1 showed very low
activity (800 U/L). In an attempt to increase its expression level, C.
farmeri EglC was expressed in Escherichia coli as an N-terminal
fusion to protein S (ProS) from Myxococcus xanthus. Results: A novel
expression vector, pET(ProS-EglC), was successfully constructed for the
expression of C. farmeri EglC in E. coli. SDS-PAGE showed that the
recombinant protein (ProS-EglC) was approximately 60 kDa. The activity
of ProS-EglC was 12,400 U/L, which was considerably higher than that of
the nature EglC (800 U/L). ProS-EglC was active at pH 6.5\u2013pH 8.0,
with optimum activity at pH 7.0. The recombinant protein was stable at
pH 3.5\u2013pH 6.5 for 30 min. The optimal temperature for activity of
ProS-EglC was 30\ub0C\u201340\ub0C. It showed greater than 50% of
maximum activity even at 5\ub0C, indicating that the ProS-EglC is a
cold-active enzyme. Its activity was increased by Co2+ and Fe2+, but
decreased by Cd2+, Zn2+, Li+, methanol, Triton-X-100, acetonitrile,
Tween 80, and SDS. Conclusions: The ProS-EglC is promising in
application of various biotechnological processes because of its
cold-active characterizations. This study also suggests a useful
strategy for the expression of foreign proteins in E. coli using a ProS
tag
Electron beam manipulation, injection and acceleration in plasma wakefield accelerators by optically generated plasma density spikes
We discuss considerations regarding a novel and robust scheme for optically triggered electron bunch generation in plasma wakefield accelerators [1]. In this technique, a transversely propagating focused laser pulse ignites a quasi-stationary plasma column before the arrival of the plasma wake. This localized plasma density enhancement or optical "plasma torch" distorts the blowout during the arrival of the electron drive bunch and modifies the electron trajectories, resulting in controlled injection. By changing the gas density, and the laser pulse parameters such as beam waist and intensity, and by moving the focal point of the laser pulse, the shape of the plasma torch, and therefore the generated trailing beam, can be tuned easily. The proposed method is much more flexible and faster in generating gas density transitions when compared to hydrodynamics-based methods, and it accommodates experimentalists needs as it is a purely optical process and straightforward to implement
Plasma-photonic spatiotemporal synchronization of relativistic electron and laser beams
Modern particle accelerators and their applications increasingly rely on precisely coordinated interactions of intense charged particle and laser beams. Femtosecond-scale synchronization alongside micrometre-scale spatial precision are essential e.g. for pump-probe experiments, seeding and diagnostics of advanced light sources and for plasma-based accelerators. State-of-the-art temporal or spatial diagnostics typically operate with low-intensity beams to avoid material damage at high intensity. As such, we present a plasma-based approach, which allows measurement of both temporal and spatial overlap of high-intensity beams directly at their interaction point. It exploits amplification of plasma afterglow arising from the passage of an electron beam through a laser-generated plasma filament. The corresponding photon yield carries the spatiotemporal signature of the femtosecond-scale dynamics, yet can be observed as a visible light signal on microsecond-millimetre scales
Electron bunch generation from a plasma photocathode
Plasma waves generated in the wake of intense, relativistic laser or particle
beams can accelerate electron bunches to giga-electronvolt (GeV) energies in
centimetre-scale distances. This allows the realization of compact accelerators
having emerging applications, ranging from modern light sources such as the
free-electron laser (FEL) to energy frontier lepton colliders. In a plasma
wakefield accelerator, such multi-gigavolt-per-metre (GV m) wakefields
can accelerate witness electron bunches that are either externally injected or
captured from the background plasma. Here we demonstrate optically triggered
injection and acceleration of electron bunches, generated in a multi-component
hydrogen and helium plasma employing a spatially aligned and synchronized laser
pulse. This ''plasma photocathode'' decouples injection from wake excitation by
liberating tunnel-ionized helium electrons directly inside the plasma cavity,
where these cold electrons are then rapidly boosted to relativistic velocities.
The injection regime can be accessed via optical density down-ramp injection,
is highly tunable and paves the way to generation of electron beams with
unprecedented low transverse emittance, high current and 6D-brightness. This
experimental path opens numerous prospects for transformative plasma wakefield
accelerator applications based on ultra-high brightness beams
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