Effect of nano-ZrC powders on microstructure and properties of 90W−7Ni−3Fe alloys

To effectively inhibit the growth of tungsten grains during the liquid phase sintering, the ZrC dispersion-strengthened heavy tungsten alloys (WHAs) were prepared by liquid phase sintering at 1500 ℃. The effects of ZrC mass fraction (1% and 2%) on the microstructure and properties of WHAs were analyzed. The results show that, with the increase of ZrC mass fraction, the relative density and W−W contiguity of WHAs decrease, and the tungsten grains are refined to a certain extent. When the ZrC mass fraction is 1%, the strength-ductility matching effect of WHAs is the best, the relative density reaches 98.4%, the tungsten grain size is 22.17 μm, and the yield strength and compressive strength (40% deformation) reach 791 MPa and 2179 MPa, respectively, which are increased by 8.35% and 38.70%, compared with WHAs without ZrC (730 MPa and 1570 MPa)

Intervening Effects of Total Alkaloids of Corydalis saxicola Bunting on Rats With Antibiotic-Induced Gut Microbiota Dysbiosis Based on 16S rRNA Gene Sequencing and Untargeted Metabolomics Analyses

Gut microbiota dysbiosis induced by antibiotics is strongly connected with health concerns. Studying the mechanisms underlying antibiotic-induced gut microbiota dysbiosis could help to identify effective drugs and prevent many serious diseases. In this study, in rats with antibiotic-induced gut microbiota dysbiosis treated with total alkaloids of Corydalis saxicola Bunting (TACS), urinary and fecal biochemical changes and cecum microbial diversity were investigated using 16S rRNA gene sequencing analysis and untargeted metabolomics. The microbial diversity results showed that 10 genera were disturbed by the antibiotic treatment, and two of them were obviously restored by TACS. The untargeted metabolomics analysis identified 34 potential biomarkers in urine and feces that may be the metabolites that are most related to the mechanisms underlying antibiotic-induced gut microbiota dysbiosis and the therapeutic effects of TACS treatment. The biomarkers were involved in six metabolic pathways, comprising pathways related to branched-chain amino acid (BCAA), bile acid, arginine and proline, purine, aromatic amino acid, and amino sugar and nucleotide sugar metabolism. Notably, there was a strong correlation between these metabolic pathways and two gut microbiota genera (g__Blautia and g__Intestinibacter). The correlation analysis suggested that TACS might synergistically affect four of these metabolic pathways (BCAA, bile acid, arginine and proline, and purine metabolism), thereby modulating gut microbiota dysbiosis. Furthermore, we performed a molecular docking analysis involving simulating high-precision docking and using molecular pathway maps to illuminate the way that ligands (the five main alkaloid components of TACS) act on a complex molecular network, using CYP27A1 (a key enzyme in the bile acid synthesis pathway) as the target protein. This study provides a comprehensive overview of the intervening effects of TACS on the host metabolic phenotype and gut microbiome in rats with gut microbiota dysbiosis, and it presents new insights for the discovery of effective drugs and the best therapeutic approaches

Study of Salidroside on Expression of Synaptophysin and Tau in Rats after Local Cerebral Ischemia-reperfusion Injury

Objective:To investigate the effect of salidroside on the expression of synaptophysin (SYN) and Tau in rats after cerebral ischemia-reperfusion injury.Methods:A total of 36 healthy adult male Sprague-Dawley rats were randomly divided into sham group (n=12) and model group (n=24). Cerebral ischemia model of middle cerebral artery occlusion (MCAO) was established in rats of model group using suture method, and the nerves function score was determined by Zeal Longa score after the animal model was fully awakened. Then the successful model rats were randomly divided into model group and salidroside group, twelve rats in each group. With occluding of middle cerebral arteries for two hours and reperfusion for 24 hours, the sham group and model group were treated with normal saline at a dose of 50 mg/kg, and the salidroside group received salidroside at a dose of 50 mg/kg by intraperitoneal injection. All rats were sacrificed 24 hours after MCAO operation. The rats were treated with drugs one more time at two hours before sacrifice. The mRNA expression of SYN and Tau in ischemic brain tissue were detected by RT-qPCR, the protein expression of phosphorylated Tau at threonine 231 (p-Tau231) was detected by immunohistochemical method, and the protein expression of SYN and p-Tau231 in ischemic brain tissue were detected by Western Blot.Results:Compared with the sham group, SYN expression in model group was decreased (P<0.05);SYN expression in salidroside group was increased compared with the model group (P<0.05); p-Tau231 expression in model group was increased compared with the sham group (P<0.01). p-Tau231 expression in salidroside group was decreased compared with model group (P<0.01).Conclusion:Salidroside can increase the injury-induced downregulation of SYN when the injury caused by MCAO, and decrease hyperphosphorylation of Tau protein in the ipsilateral thalamus of rats after cerebral ischemia-reperfusion injury

Effect of Perchlorate on Combustion Properties of Directly-Written Al/PVDF Composites

Metastable intermolecular composites (MICs) based on Al/PVDF have become one of the most important materials in the field of additive manufacturing of energetic materials due to their high energy density and designability. In this work, the energy utilization efficiency and energy release performance of directly written Al/PVDF composites were regulated by introducing ammonium perchlorate (AP) and potassium perchlorate (KP) as gas generators and oxidants. The effect of AP/KP on the combustion performance of MICs systems has been studied in depth. It was found that the addition of AP/KP can increase the combustion temperature and flame duration of the Al/PVDF system. Moreover, the flame propagation rate of the Al/PVDF system decreases as AP/KP addition increases. Therefore, the strategy of introducing AP/KP into directly written Al/PVDF composites can effectively control the energy performance of this energetic system, thereby promoting its practical application in propellants, heterogeneous explosives and gas generators.</jats:p

Experimental Study on the Strength Characteristics of Expansive Soils Improved by the MICP Method

Microbially induced calcite precipitation (MICP) has been a promising method to improve geotechnical engineering properties; however, there are few literatures about the application of the MICP method to improve the strength characteristics of expansive soils with low permeability. In this paper, a series of CD triaxial tests were carried out to investigate the effect of the MICP method on the strength characteristics of the expansive soils. The results show that the shear strength of the specimens increased with the increase in the cementation solution and eventually reached a stable value. The MICP method can significantly improve the shear strength index of the expansive soils. The cohesion of the expansive soils was increased from 29.52 kPa to 39.41 kPa, and the internal friction angle was increased from 20.13° to 29.58°. The stress-strain curves of expansive soil samples improved by the MICP method show a hyperbolic relationship, which is characterized by strain hardening. The hyperbolic model was chosen to describe the stress-strain relationship of the expansive soils improved by the MICP method, and the predicted results were in good agreement with the measured results. Moreover, we performed a scanning electron microscope (SEM) experiment and revealed the mechanism of the MICP method to improve the strength characteristics of expansive soils. The conclusions above can provide a theoretical basis to further study the strength characteristics of improved expansive soils by the MICP method.</jats:p

Small Molecule Inhibitors Specifically Targeting the Type III Secretion System of Xanthomonas oryzae on Rice

The initiative strategy for the development of novel anti-microbial agents usually uses the virulence factors of bacteria as a target, without affecting their growth and survival. The type III secretion system (T3SS), one of the essential virulence factors in most Gram-negative pathogenic bacteria because of its highly conserved construct, has been regarded as an effective target that developed new anti-microbial drugs. Xanthomonas oryzae pv. oryzae (Xoo) causes leaf blight diseases and is one of the most important pathogens on rice. To find potential anti-virulence agents against this pathogen, a number of natural compounds were screened for their effects on the T3SS of Xoo. Three of 34 compounds significantly inhibited the promoter activity of the harpin gene, hpa1, and were further checked for their impact on bacterial growth and on the hypersensitive response (HR) caused by Xoo on non-host tobacco plants. The results indicated that treatment of Xoo with CZ-1, CZ-4 and CZ-9 resulted in an obviously attenuated HR without affecting bacterial growth and survival. Moreover, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis showed that the expression of the Xoo T3SS was suppressed by treatment with the three inhibitors. The mRNA levels of representative genes in the hypersensitive response and pathogenicity (hrp) cluster, as well as the regulatory genes hrpG and hrpX, were reduced. Finally, the in vivo test demonstrated that the compounds could reduce the disease symptoms of Xoo on the rice cultivar (Oryza sativa) IR24

Effect of Perchlorate on Combustion Properties of Directly-Written Al/PVDF Composites

Metastable intermolecular composites (MICs) based on Al/PVDF have become one of the most important materials in the field of additive manufacturing of energetic materials due to their high energy density and designability. In this work, the energy utilization efficiency and energy release performance of directly written Al/PVDF composites were regulated by introducing ammonium perchlorate (AP) and potassium perchlorate (KP) as gas generators and oxidants. The effect of AP/KP on the combustion performance of MICs systems has been studied in depth. It was found that the addition of AP/KP can increase the combustion temperature and flame duration of the Al/PVDF system. Moreover, the flame propagation rate of the Al/PVDF system decreases as AP/KP addition increases. Therefore, the strategy of introducing AP/KP into directly written Al/PVDF composites can effectively control the energy performance of this energetic system, thereby promoting its practical application in propellants, heterogeneous explosives and gas generators

Experimental Study on the Strength Characteristics of Expansive Soils Improved by the MICP Method

Microbially induced calcite precipitation (MICP) has been a promising method to improve geotechnical engineering properties; however, there are few literatures about the application of the MICP method to improve the strength characteristics of expansive soils with low permeability. In this paper, a series of CD triaxial tests were carried out to investigate the effect of the MICP method on the strength characteristics of the expansive soils. The results show that the shear strength of the specimens increased with the increase in the cementation solution and eventually reached a stable value. The MICP method can significantly improve the shear strength index of the expansive soils. The cohesion of the expansive soils was increased from 29.52 kPa to 39.41 kPa, and the internal friction angle was increased from 20.13° to 29.58°. The stress-strain curves of expansive soil samples improved by the MICP method show a hyperbolic relationship, which is characterized by strain hardening. The hyperbolic model was chosen to describe the stress-strain relationship of the expansive soils improved by the MICP method, and the predicted results were in good agreement with the measured results. Moreover, we performed a scanning electron microscope (SEM) experiment and revealed the mechanism of the MICP method to improve the strength characteristics of expansive soils. The conclusions above can provide a theoretical basis to further study the strength characteristics of improved expansive soils by the MICP method