To investigate the destructive effects of erythromycin on biofilm of MRSA and find the effect of erythromycin on QS related factors.
Tested the MBC of erythromycin on MRSA.Established the model of ...biofilm.Erythromycin was added into the medium when bacteria were inoculated for 24 h. Tested the biofilm and collected the supernatant or serum of rat at 6, 12, 24, 48, 72 h and 7 d after adding erythromycin to detect the concentration of autoinducing peptides (AIP).
The MBC of the erythromycin on standard strains of MRSA was 256 g/L.There is a decreasing tendency of biofilm in a short time after adding erythromycin or TSB and then gradually increase until to a steady state. Biofilm of experimental group(1.348, 1.236, 1.667)were significantly less than the control group(1.789, 1.712, 2.349,
<0.05)at 12, 24, 48 h. Adding erythromycin to the mature biofilm, there was a significant decrease of biofilm.Adding erythromycin within 3 hours after inoculating bacteria, there was no bacterial growth or biofilm formation. The
The use of celecoxib is associated with a significant decrease in breast cancer risk. However, the long-term use of high-dose celecoxib might be limited owing to cardiovascular side effects. In this ...study, we found that acetylbritannilactone (ABL), extract from a Chinese medicinal herb, could reduce celecoxib dose and potentiate the growth-inhibitory effect in breast cancer cells. ABL enhanced the apoptotic effect of celecoxib in COX-2-expressing cells, but had little effect in COX-2-negative cells. The apoptosis induced by the combination treatment disappeared when COX-2 was knocked down, whereas the lack of apoptotic effects in COX-2-negative cells was reversed after COX-2 transfection. However, the combination treatment induced a G(0)/G(1) phase arrest independent of whether or not the cells expressed COX-2. The G(0)/G(1) arrest was attributed to a decreased expression of cyclinD1, cyclinE, CDK2 and CDK6, especially the upregulation of p21. In addition, inhibition of Akt and p38 signaling pathways was required by the synergism, as the constitutively active Akt and p38 protected cells against apoptosis and cell cycle arrest induced by the combination treatment. In vivo, administration of celecoxib and ABL were more effective than the individual agents against xenograft tumor growth. Thus, our data suggested that the combinatorial approach of celecoxib and ABL might be helpful for breast cancer treatment.
•A unified physics-informed machine learning (PIML) approach with simplicity, high-efficiency and high-accuracy is developed to predict the notch fatigue life of polycrystalline ...alloys.•Physics-informed parameters are introduced into the PIML model to reach a better predictive performance and generalization capability than physics-based models.•The key feature parameters for notch fatigue are accurately identified by the global sensitivity analysis method.•PIML model based on Latin hypercubic sampling achieves the prediction of probabilistic fatigue life and uncertainty assessment.
Within this work, a unified physics-informed machine learning (PIML) framework is proposed for notch fatigue life prediction and key feature parameters identification of aerospace polycrystalline alloys. The unified PIML approach reaches a capable accuracy in notch fatigue life prediction of the polycrystalline alloys under a wide range of notch geometries and loading conditions compared with physics-based life models. In addition, the global sensitivity analysis method is used to accurately identify the key feature parameters that affect the notch fatigue life. The nominal maximum stress and unnotched specimen reference life are recognized as highly relevant features for notch fatigue life whereas the notch root radius is the key parameter among the notch parameters. Finally, life uncertainty induced by the notch geometry parameters is performed by using the proposed PIML model based on Latin hypercube sampling, which accomplishes the probabilistic estimation of notch fatigue life well. In practical applications, the PIML framework can be applied efficiently to notch fatigue life prediction of a new material dataset due to its powerful generalization ability without additional parameter fitting or finite element analysis. The well-trained PIML model and the uncertainty assessment method provide potential tools for notch fatigue evaluation under complex loading conditions.
The evolutions of MHD instability behaviors and enhancement of both electrostatic and electromagnetic turbulence towards the plasma disruption have been clearly observed in the HL-2A plasmas. Two ...types of plasma disruptive discharges have been investigated for similar equilibrium parameters: one with a distinct stage of a small central temperature collapse (Formula: see text 5-10%) around 1 millisecond before the thermal quench (TQ), while the other without. For both types, the TQ phase is preceded by a rotating 2/1 tearing mode, and it is the development of the cold bubble from the inner region of the 2/1 island O-point along with its inward convection that causes the massive energy loss. In addition, the micro-scale turbulence, including magnetic fluctuations and density fluctuations, increases before the small collapse, and more significantly towards the TQ. Also, temperature fluctuations measured by electron cyclotron emission imaging enhances dramatically at the reconnection site and expand into the island when approaching the small collapse and TQ, and the expansion is more significant close to the TQ. The observed turbulence enhancement near the X-point cannot be fully interpreted by the linear stability analysis by GENE. Evidences suggest that nonlinear effects, such as the reduction of local Formula: see text shear and turbulence spreading, may play an important role in governing turbulence enhancement and expansion. These results imply that the turbulence and its interaction with the island facilitate the stochasticity of the magnetic flux and formation of the cold bubble, and hence, the plasma disruption.
•The effects of rafting extent, type and orientation on the monotonic and cyclic deformation behaviours are investigated.•The deformed γ'/γ microstructure and dislocation configurations under ...different rafting states are characterized.•A microstructural state-based constitutive model to account for the role of rafting extent and type is proposed.•The rafting morphology-related Bauschinger effect during cyclic deformation is well captured by a micromechanics-based back stress model.
Monotonic tensile and cyclic deformation behaviours are investigated under different microstructural rafting states of a SC Ni-based superalloy, with emphasis on the influences of the rafting extent, type and loading orientation. The deformed microstructures and the dislocation configurations are characterized to give a micro-based understanding on the varying of deformation behaviours due to rafting. It is found that the decreases in the initial yield point and cyclic stress amplitude are only related to the rafting extent. Nevertheless, the rafting type (namely, the plate-like and needle-like morphology) has an undeniable contribution to the shape of hysteresis loops, where the plate-like rafting morphology results in more significant Bauschinger effect than needle-like rafting morphology. The variation of monotonic and cyclic deformation induced by rafting shares affinity with the alteration of internal stress and the movement of dislocations. Afterwards, a microstructure-sensitive constitutive model with two-phase flow rules has been developed. The effect of rafting on the monotonic and cyclic stress-strain responses is captured by introduce a series of microscopic mechanisms and a micromechanics-based back stress model that considers the morphology and size of the γ'/γ two-phase structures. The developed model is used to simulate the macroscopic stress-strain responses of the SC Ni-based superalloy under different rafting states. Model predictions are in good agreement with tests, capturing the reduction of cyclic stress amplitudes and the change in hysteresis loops. Finally, the impacts of the two-phase flow rules and the micromechanics-based back stress on the simulation capability have been discussed.
During the development of thermal protection materials for hypersonic vehicles, the simulated ablation test based on thermal plasma has been widely used. In this paper, a small plasma multi-phase ...flow simulation ablation test system is designed based on the automatic control technology. After the overall design, hardware processing and software development are completed. Then the system parameters are calculated and tested by numerical calculation methods and heat flow densitometers as well as other test instruments. The results show that the system has high enthalpy, high temperature and high heat flux, and solid particles can be injected in it to simulate particle erosion effects. The system can generate plasma jet with continuously adjustable parameters. The stagnation point temperature is 11651 K and the central speed is 1222 m*s−1. The particle addition rate is continuously and adjustable. The maximum speed in the experiment is 280 m*s−1, and the surface temperature is about 2650°C. The work in this paper provides an important way for more inexpensive and efficient ablation tests of thermal protection material. The results provide a useful reference for the selection of the relevant material's ablation test parameters.
ABSTRACT
A simple method to analyse the notch sensitivity of specimens in fatigue tests is presented. The parameter m, which can be used to measure the notch sensitivity, the nominal stress and the ...stress concentration factor (Kt) are used to establish the method. In order to verify the feasibility of the method, notch fatigue test results from our group and literatures were collected. The results reveal that an optimal value of parameter m does exist for each material. Life predictions indicated that the model is able to describe the life evolution for notched specimens under high cycle fatigue and low cycle fatigue tests. Because the geometry effect is accounted for Kt, the method is suitable for the conditions when the notch geometries and the absolute dimensions are similar to the tested specimens.
Nanosized ZnO with prismatic form was prepared using homogeneous precipitation process and its electrochemical performance was investigated by the measurements of electrochemical cycle behaviors and ...passivation polarization curves. The discharge capacity delivered by nanosized ZnO still achieved about 600
mAh/g until the 250th cycle. Nanosized ZnO exhibited higher midpoint discharge voltage, better cycle stability and passivation toleration than commercial ZnO. Furthermore, nanosized ZnO showed the morphology evolution process differed slightly from that of the commercial ZnO, including morphology maintenance, orientation growth and the formation of Zn dendrites. The epitaxial growth, texture growth and crystal growth habit were put forward to illuminate the morphology evolution process.
Self-designed oxygen-kerosene ablation system was employed to study the ablation characteristics of silicone rubber based thermal insulation materials under the condition of boron oxide particles ...erosion. The ablation test was designed with a mass fraction of 1.69% boron oxide particles and particles-free, the microstructure and elemental analysis of the specimens before and after ablation were carried out by Scanning Electron Microscopy (SEM) and Energy Dispersion Spectrum (EDS). Experiment results show that the average mass ablation rate of the materials was 0.0099 g*s−1 and the average ablation rate was -0.025 mm*s−1 under the condition of pure gas phase ablation; and the average mass ablation rate of the multiphase ablation test group was 0.1775 g*s−1, whose average ablation rate was 0.437 mm*s−1; during the ablation process, the boron oxide particles would adhere a molten layer on the flame contact surface of the specimen, which covering the pores on the material surface, blocking the infiltration channel for the oxidizing component and slowing down the oxidation loss rate of the material below the surface, but because the particles erosion was the main reason for material depletion, the combined effect of the above both led to the upward material ablation rates of Silicone Rubber.
Theoretical and molecular modeling studies have been conducted for understanding the details of how 3-(2,4-dimethoxy)benzylidene-anabaseine dihydrochloride (GTS-21) and its metabolism derivatives ...bind with the receptor of α7 nicotinic acetylcholine dimer. Good accordance with experimental results has been achieved. It was found that the van der Waals repulsion makes the dominant contribution to the binding energy. GTS-21 and its metabolites are apparently too large for the binding sites of the α7 dimer. To improve the effectiveness of the drug, a possible approach is to reduce its volume while maintaining the presence of the active groups. Our studies, in combination with experimental studies, will lead to a promising basis for practical drug design against Alzheimer’s disease.
PDF
