The CoCrBFeNiSi high-entropy alloy (HEA) coatings were fabricated on H13 steel using different laser powers. The microstructure, mechanical and chemical properties of the coating and the internal ...relations between them were investigated, in which 3D wear trace morphology was adopted to analyze the wear resistance of different coatings. The coatings could be divided into three layers with different microstructure including the bottom dendritic layer, the upper amorphous layer and the transition layer. The amorphous content in the coatings was dependent upon laser power which influenced dilution rate and actual cooling rate through changing heat input. Increased amorphous content led to increased microhardness of the coatings which could approach five times of that of the substrate. When the amorphous content decreased, cladded coatings exhibited deeper furrows, more serious adhesive wear and oxidation wear, which gave birth to wider cross section area of the worn track, higher wear weight loss and thus deteriorated wear resistance of the coatings. Moreover, higher amorphous content in the coatings had led to more excellent corrosion resistance to HCl and NaCl solution.
•The heat affected zone consists of α(Al), η(MgZn2), Al2MgCu, and Al6Mn phases.•The tensile fracture style along the thickness direction is ductile/brittle composite fracture and leads to obvious mechanical anisotropy of the HAZ.•Brittle cracks are related to the original microstructure of the base metal and the intergranular continuous distribution of Al2MgCu phase as a result of welding thermal cycling.
Purpose
Ischemia is one of the most familiar complications in the different procedures for moyamoya disease (MMD), but the optimal surgical approaches for MMD remain unknown. We aimed to evaluate the ...efficiency of various surgical treatments.
Methods
A literature search word was performed through four databases such as Cochrane Library, Web of Science, PubMed, and EMBASE for the literature published until May 2021. The I2 statistic was used to assess heterogeneity. A random/fixed‐effects model was used to pool.
Results
There are a total of 18 studies including three surgical treatments such as including indirect, direct, and combined bypass in this study. The result revealed that indirect bypass was related to a higher incidence of recurrence stroke compared to the direct and combined bypass treatment (p = .001). Furthermore, the cases undergoing direct bypass were associated with a better angiographic change than the indirect bypass (OR = 3.254, p = .013).
Conclusion
This meta‐analysis demonstrated a positive effect of using the direct and combined bypass to treat MMD compared to indirect bypass due to their lower rates of recurrence stroke.
An amorphous coating was synthesized on low carbon steel by laser cladding Co-based self-fluxed alloy powder successfully. The microstructure, thermal stability property of the fabricated amorphous ...coating was investigated. The thickness of amorphous coating was 400µm while the dendrite zone was only 10µm height near the interface. The volume fraction of amorphous was 85.1% approximately. DSC curve showed that the glass transition temperature and the crystallization temperature were 298°C and 342°C, respectively. The supercooling liquid region was 44°C which ensured the high thermal stability of amorphous coating against crystallization.
•Amorphous coating was fabricated by using ordinary Co-based self-fluxed alloy powder.•Amorphous phase accounted for 85.1% of the coating.•The supercooling liquid region was 44°C.
Co-based coating has been fabricated on Ti-6Al-4V (TC4) titanium alloy by laser cladding. The phase composition and microstructure of the coating were analyzed using metallurgical microscope (MM), ...scanning electron microscope (SEM), x-ray diffraction (XRD), energy-dispersive spectroscopy (EDS) and transmission electron microscopy (TEM), respectively. The microhardness, high temperature wear resistance and corrosion resistance of the coating were investigated by performance tests. The results show that the coating was mainly composed of CoTi, CoTi
2
and Co
0.5
Cr
1.5
Ti crystalline phases and an amorphous phase. The microhardness of the coating was twice that of the titanium alloy substrate. The value of friction and wear coefficient of the coating was lower and more stable, and the wear mass loss decreased by 52% as compared with the substrate in the high-temperature friction and wear test. The oxidative wear mechanism in the condition of high temperature friction and wear was studied. Moreover, the coating exhibited better corrosion resistance than the substrate in both NaCl and H
2
SO
4
electrolyte solutions.
CoFeCrNiSiB high-entropy alloy coatings with different content of REO (rare earth oxide) CeO2 were fabricated on the surface of corrosion-resistance steel plates by using laser cladding process. The ...surface properties of the cladded coatings including wear and corrosion resistance were evaluated by friction wear equipment and electrochemical workstation, respectively, while the microstructure was observed by scanning electron microscope, energy dispersive spectrometer, x-ray diffractor and transmission electron microscope. When the CeO2 content was not higher than 2%, the wear resistance and corrosion resistance of cladded coating was improved with the increased of CeO2 content. However, when the CeO2 content was between 2% and 4%, the wear resistance and corrosion resistance of cladded coatings decreased with the increased of CeO2 content. The corrosion resistance evaluation environment included 2 N(1 mol l−1) H2SO4 and 5 wt% NaCl solutions. Equi-axed grains of the cladded coatings got refined by adding CeO2, the grains were most refined at 2% in the range of 0%-4% CeO2 content. However, when too much CeO2 (>2%) was added, CeO2 would exist as an oxide in the intergranular area. Therefore, grain refinement could improve the surface properties of coatings, while the presence of intergranular oxides would make the surface properties of coatings worse.
•Cilostazol promotes fatty acid mitochondrial β-oxidation (β-FAO) in C2C12 myotubes.•Cilostazol reduced triacylglycerol (TAG) accumulation and secretion.•PKA/CREB/PGC-1α pathway is involved in the ...effects of cilostazol in β-FAO.
Cilostazol is a drug licensed for the treatment of intermittent claudication. Its main action is to elevate intracellular levels of cyclic monophosphate (cAMP) by inhibiting the activity of type III phosphodiesterase, a cAMP-degrading enzyme. The effects of cilostazol on fatty acid oxidation (FAO) are as yet unknown. In this study, we report that cilostazol can elevate complete FAO and decrease both triacylglycerol (TAG) accumulation and TAG secretion. This use of cilostazol treatment increases expression of PGC-1α and, subsequently, its target genes, such as ERRα, NOR1, CD36, CPT1, MCAD, and ACO. Expression of these factors is linked to fatty acid β-oxidation but this effect is inhibited by H-89, a specific inhibitor of the PKA/CREB pathway. Importantly, knockdown of PGC-1α using siRNA abolished the effects of cilostazol in fatty acid oxidation (FAO) and TAG metabolism. These findings suggested that the PKA/CREB/PGC-1α pathway plays a critical role in cilostazol-induced fatty acid oxidation and TAG metabolism.
Osthole (7-methoxy-8-isoamyl alkenyl coumarin) has been reported to exhibit marked anticancer effects on several types of cancer. The expression levels of matrix metalloproteinase-9 (MMP-9) are ...closely associated with the pathogenesis of glioma. Furthermore, it is reported that the upregulation of microRNA‑16 (miR‑16) by the MMP‑9 signaling pathway can restrain the proliferation of cancer cells. To examine whether osthole increases the anticancer effect on human glioma cells in the present study, the common glioma cell line, U87, was treated with osthole at concentrations of 0, 50, 100 and 200 µΜ. The effects of osthole on cell viability were determined using a 3‑(4,5‑dimethylthiazol‑2‑thiazolyl)‑2,5‑diphenyl‑tetrazolium bromide assay. The rate of cellular apoptosis was analyzed by measuring the activity of caspase‑3 and using flow cytometry. The expression of MMP‑9 was determined using gelatin zymography assays and the expression of miR‑16 was determined using reverse transcription‑quantitative polymerase chain reaction. The results demonstrated that osthole significantly suppressed the proliferation and accelerated the apoptosis of the U87 cells. Furthermore, increased expression levels of miR‑16 and reduced protein expression levels of MMP‑9 were found in the U87 cells. In addition, miR‑16 was found to regulate the expression of MMP‑9 in the U87 cells through transfection of miR‑16 precursor and anti‑miR‑16 into the U87 cells. In conclusion, these observations indicated that osthole suppressed the proliferation and accelerated the apoptosis of human glioma cells through upregulation of the expression of miR‑16 and downregulation of the expression of MMP-9.
The microstructure and tensile mechanical properties of multi-layer multi-channel TIG welded joints of Al-Zn-Mg alloy plates were studied in this paper. The mechanical properties of the welded joint ...including microhardness and tensile performance were tested, respectively, while the microstructure was observed by scanning electron microscope, energy dispersive spectrometer, x-ray diffractor and transmission electron microscope. A short rod-shaped MgZn2 phase and a strip-shaped Al3Mg2 phase were found in the intergranular column of the weld seam, and an ellipsoidal MgZn2 phase was found in the intragranular column. The EDS test results of the micro-fracture and the fracture surface of the tensile specimen indicated that these particles could act as a strengthening phase or a crack source during the tensile fracture process. In addition, the distribution of microhardness in the weld zone was investigated.
PDF
