Hot ductility behavior of a Fe-0.3C-9Mn-2Al medium Mn steel

The hot ductility of a Fe-0.3C-9Mn-2Al medium Mn steel was investigated using a Gleeble3800 thermo-mechanical simulator.Hot tensile tests were conducted at different temperatures(600-1300℃)under a constant strain rate of 4×10^(−3)s^(−1).The fracture behavior and mechanism of hot ductility evolution were discussed.Results showed that the hot ductility decreased as the temperature was decreased from 1000℃.The reduction of area(RA)decreased rapidly in the specimens tested below 700℃,whereas that in the specimen tested at 650℃was lower than 65%.Mixed brittle-ductile fracture feature is reflected by the coexistence of cleavage step,intergranular facet,and dimple at the surface.The fracture belonged to ductile failure in the specimens tested between 720-1000℃.Large and deep dimples could delay crack propagation.The change in average width of the dimples was in positive proportion with the change in RA.The wide austenite-ferrite intercritical temperature range was crucial for the hot ductility of medium Mn steel.The formation of ferrite film on austenite grain boundaries led to strain concentration.Yield point elongation occurred at the austenite-ferrite intercritical temperature range during the hot tensile test.

Lithium inhibits proliferation of human esophageal cancer cell line Eca-109 by inducing a G_2/M cell cycle arrest

AIM： To investigate the effect of lithium on proliferation of esophageal cancer （EC） cells and its preliminary mechanisms. METHODS： Eca-109 cells were treated with lithium chloride, a highly selective inhibitor of glycogen synthase kinase 31） （GSK-31））, at different concentrations （2-30 mmol/L） and time points （0, 2, 4, 6 and 24 h）. Cell proliferative ability was evaluated by 3-（4,5-Dimethylthiazol-2-yl）-2, 5-diphenyltetrazolium bromide （MTT） assay, and Cell cycle distribution was examined by flow cytometry. Expressions of p-GSK-3β, β-catenin, cyclin B1, cdc2 and cyclin D1 protein were detected by Western blotting, and the subcellular localization of β-catenin was determined by immunofluorescence. The mRNA level of of cyclin B1 was detected by reverse transcription polymerase chain reaction （RT-PCR）. RESULTS： Lithium could inhibit the proliferation of Eca-109 cells. Lithium at a concentration of 20 mmol/L lithium for 24 h produced obvious changes in the distribution of cell cycle, and increased the number of cells in G2/M phase （P 〈 0.05 vs control group）. Western blotting showed that lithium inhibited GSK-β） by Ser-9 phosphorylation and stabilized free β-catenin in the cytoplasm. Immunofluorescence further confirmed that free β-catenin actively translocated to the nucleus. Horeover, lithium slightly elevated cyclin D1 protein expression, whereas lowered the cyclin B1 expression after 24 h lithium exposure and no obvious change was observed for cdc2 protein. CONCLUSION： Lithium can inhibit the proliferation of human esophageal cancer cell line Eca-109 by inducing a G2/H cell cycle arrest, which is mainly mediated through the inhibition of lithium-sensitive molecule, GSK-3β, and reduction of cyclin B1 expression.

Orexin receptor type 2 agonism inhibits thermogenesis in brown adipose tissue by attenuating afferent innervation

Orexin signaling has been associated with energy expenditure and brown adipose tissue(BAT)function.However,conflicting data exist in the field about how orexin signaling regulates BAT thermogenesis.In this study,we show that a specific orexin receptor type 2(OX2R)agonist[Ala11,D-Leu15]-OxB(OB-Ala)inhibited intrascapular brown adipose tissue(iBAT)thermogenesis by reducing sympathetic output to iBAT.This effect is mediated by OX2Rs located on afferent nerve endings innervating iBAT instead of brown adipocyte itself.Microinjection of OB-Ala into iBAT inhibited iBAT thermogenesis in mice upon cold exposure and neuronal activity in the paraventricular nucleus.Findings suggest that OB-Ala could inhibit iBAT thermogenesis by attenuating sensory input thereby inhibiting the sympathetic-sensory iBAT feedback loop.Our study uncovers a novel primary action site of orexin in the regulation of energy balance.

Effect of milrinone on the cardiac function and N-terminal pro-brain natriuretic peptide levels in patients with senile refractory heart failure

Objective:To study the effect of milrinone on the cardiac function and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels in patients with senile refractory heart failure. Methods:90 patients with senile refractory heart failure who were treated in our hospital between August 2013 and August 2016 were collected and divided into control group (n=45) and observation group (n=45) according to the random number table. The control group received regular clinical treatment, and the observation group received regular + milrinone treatment. The cardiac function and serum NT-proBN contents were compared between two groups of patients before and after treatment.Results: Before treatment, the differences in ultrasound and serum cardiac function indexes and serum NT-proBN levels were not statistically significant between two groups of patients. After treatment, ultrasound serum cardiac function parameter LVEDD level in observation group was lower than that in control group while CI and SV levels were higher than those in control group;serum cardiac function indexes Cys-C, GDF-15, sST2 and H-FABP contents were lower than those in control group;serum NT-proBNP content was lower than that in control group.Conclusion: Milrinone therapy can optimize the cardiac function and reduce the serum NT-proBN levels in patients with senile refractory heart failure.

Phase Transformation and Carbide Precipitation of Functional Gradient Semi-solid 9Cr18 Steel

The unique phase transformation and carbide evolution in 9Cr18 steel were investigated during semi-solid forming and subsequent heat treatment. The functional gradient thixoforging 9Cr18 component was divided into inner area and edge area. Microstructure evolution was different at each area. After semi-solid cooling, the solid particles in the inner area were retained as meta-austenite. During annealing, M_（23）C_6 carbide began to precipitate when temperature reached 700 °C.Martensite transformation occurred when temperature reached 800 °C. The occurrence of M_（23）C_6 carbide and martensite structure would be harmful to the mechanical properties of inner area. In the edge area, the liquid underwent eutectic transformation to form bar-shape M_7C_3 carbide and secondary austenite after semi-solid cooling. The width of bar-shape carbide would decrease during annealing. By controlling the carbide evolution, we could tailor the functional gradient material with required property.

Constitutive Modeling for Thixoforming of 9Cr18 Semi-solid Alloy and 3D Forecast Mapping

Thixotropic Compression tests were carried out on 9Cr18 semi-solid alloy through Gleeble-1500 thermal simulation machine. According to the experiment analysis, macro separation occurred during thixoforming. The liquid film was extruded outside to the surface and solidified to form eutectic structure. The solid particles were connected with each other and underwent plastic deformation. According to the comparison between Zhou-Guan model and modified Zhou-Guan model, it could be observed that the adding of thixotropic factor played an important role in the regression and the latter one was more credible. The modified Zhou-Guan model could well describe the thixoforming behavior. 3D forecast mapping was built for 9Cr18 semi solid alloy in thixoforming temperature range. It would provide valuable information for selecting process parameters during thixoforming in the manufacture process.

Effects of Temperature and Strain Rate on Solid-/Liquid-Phase Flow Behavior of 9Cr18 Steel During Thixoforging

A thixoforging process of the 9Cr18 steel was conducted in a designed setup, and a kind of multi-diameter component was fabricated. The effects of the forming temperature and the strain rate on the solid-/liquid-phase flow behavior were discussed. The results showed that functional gradient properties of the 9Cr18 steel could be obtained after thixoforging. Changes of microstructure along radial direction could be obtained. Solid austenite was retained after fast cooling, and the liquid film enriched in alloying elements was extruded outside to form a dendrite skin layer. As temperature increased, more molten liquid formed during thixoforging. A heterogeneous flow phenomenon was activated as free liquid channels were formed. The macro-separation of solid and liquid phases was critical for the formation of functional gradient properties. Above 1300 ℃, full dendrite skin layer could be formed. The strain rate affected the thixotropic property via influencing the deformation time of thixoforging. In the presence of lower strain rates, there was more time for the flow of liquid metal, which was the key to the extension of the thixotropic stage. High temperatures and low strain rates contributed to the formation of full skin layer for the designed specimen. The average thickness of skin layer for current specimen could be over 1000 ktm when thixoforged at 1340 ℃ and under a strain rate of 0.02 s^-1.

On-chip optical interconnect using visible light

We propose and fabricate a monolithic optical interconnect on a GaN-on-silicon platform using a wafer-level technique. Because the InGaN/GaN mukiple-quantum-well diodes （MQWDs） can achieve light emission and detection simultaneously, the emitter and collector sharing identical MQW structure are produced using the same process. Suspended waveguides interconnect the emitter with the collector to form in-plane light coupling. Monolithic optical interconnect chip integrates the emitter, waveguide, base, and collector into a multi-component system with a common base. Output states superposition and 1 × 2 in-piane light communication are experimentally demonstrated. The proposed monolithic optical interconnect opens a promising way toward the diverse applications from in-plane visible light communication to light-induced imaging, and optical sensing. artificial synaptic devices, intelligent display, on-chip