Thickness-related synchronous increase in strength and ductility of ultrafine-grained pure aluminum sheets

To explore the specimen size effect of mechanical behavior of ultrafine-grained(UFG)materials with different structures,UFG Al sheets processed by equal channel angular pressing(ECAP)were selected as target materials and the dependency of tensile behavior on sheet thickness(t)was systematically investigated.The strength and ductility of ECAPed UFG Al sheets were improved synchronously as t increased from 0.2 to 0.7 mm,and then no apparent change occurred when t reached to 0.7 and 1.0 mm.The corresponding microstructure evolved from dislocation networks in equiaxed grains into the walls and subgrains and finally into the dominated cells in elongated grains or subgrains.Meanwhile,dense shear lines(SLs)and shear bands(SBs)were clearly observed and microvoids and cracks were initiated along SBs with the increase of t.These observations indicated that the plastic deformation of UFG Al sheets was jointly controlled by shear banding,dislocation sliding,and grain-boundary sliding.Furthermore,the propagation of SBs became difficult as t increased.Finally,the obtained results were discussed and compared with those of annealed UFG Al and UFG Cu.

GW842166X Alleviates Osteoarthritis by Repressing LPS-mediated Chondrocyte Catabolism in Mice

Objective To explore the role and underlying mechanism of GW842166X on osteoarthritis and osteoarthritis-associated abnormal catabolism.Methods The extracted mouse chondrocytes were treated with GW842166X followed by lipopolysaccharide(LPS).The chondrocytes were divided into the control group,LPS group,LPS+50 nmol/L GW842166X group,and LPS+100 nmol/L GW842166X group.The cytotoxicity of GW842166X was tested using the CCK-8 assay.Western blot,RT-qPCR,and ELISA were applied to evaluate the expression of the inflammatory biomarkers in mouse chondrocytes.The expression of extracellular matrix molecules was detected by the Western blot,RT-qPCR,and immunofluorescence.Additionally,the activity of NF-κB was checked by the Western blot and immunofluorescence.The mouse Hulth models were generated to examine the in vivo effects of GW842166X on osteoarthritis.Hematoxylin and eosin staining,safranin O/fast green staining,and immunohistochemistry were applied to detect the histological changes.Results GW842166X below 200µmol/L had no cytotoxicity on the mouse chondrocytes.LPS-induced high expression of TGF-β1,IL-10,TNF-α,and IL-6 was significantly reduced by GW842166X.In addition,GW842166X upregulated the expression of aggrecan and collagen type III,which was downregulated after the LPS stimulation.The upregulated expression of ADAMTS-5 and MMP-13 by LPS stimulation was dropped in response to the GW842166X treatment.Furthermore,LPS decreased the IκBαexpression in the cytoplasm and increased the nuclear p65 expression.However,these changes were reversed by the GW842166X pretreatment.Moreover,the damages in the knees caused by the Hulth surgery in mice were restored by GW842166X.Conclusion GW842166X impeded the LPS-mediated catabolism in mouse chondrocytes,thereby inhibiting the progression of osteoarthritis.

Variation of the uniaxial tensile behavior of ultrafine-grained pure aluminum after cyclic pre-deformation

To explore the influence of cyclic pre-deformation on the mechanical behavior of ultrafine-grained（UFG）materials with a high stacking fault energy（SFE）,UFG Al processed by equal-channel angular pressing（ECAP）was selected as a target material and its tensile behavior at different pre-cyclic levels D（D=N_i/N_f,where N_i and N_f are the applied cycles and fatigue life at a constant stress amplitude of 50 MPa,respectively）along with the corresponding microstructures and deformation features were systematically studied.The cyclic pre-deformation treatment on the ECAPed UFG Al led to a decrease in flow stress,and a stress quasi-plateau stage was observed after yielding for all of the different-state UFG Al samples.The yield strengths_（YS）,ultimate tensile strengths_（UTS）,and uniform straineexhibited a strong dependence on D when D≤20%;however,when D was in the range from 20%to 50%,no obvious change in mechanical properties was observed.The micro-mechanism for the effect of cyclic pre-deformation on the tensile properties of the ECAPed UFG Al was revealed and compared with that of ECAPed UFG Cu through the observations of deformation features and microstructures.

Comparison of Intraperitoneal and Intratesticular GY Y4137 Therapy for the Treatment of Testicular Ischemia Reperfusion Injury in Rats

The efficacy of intraperitoneal GY Y4137 therapy and intratesticular GY Y4137 therapy in an experimental rat model was investigated.Four groups were set up as the sham-operation group,torsion/detorsion(T/D)group,T/D plus intraperitoneal GY Y4137(G-IP)group,and T/D plus intratesticular GY Y4137(G-IT)group.In order to establish a testicular T/D model,the left testis was opcrated and the rotation reached 720°clockwise which lasted 1 h before reperfiusion.The G-IP group accepted 100 umol/kg of GY Y4137 intraperitoneally 30 min after testicular rotation,while the G-IT group was treated with the same dose by intratesticular injection.Six h after detorsion,the testis was collcted and subsequently asssed.The T/D group showed signifcant changes in histology and an enhancement in the level of oxidative stress and apoptosis compared to the sham-operation group.The expression of Caspase-3 and Bax turmed out to be strengthened by T/D and relatively decreased with GY Y4137 treatment in both the G-IP and G-IT groups.Moreover,the Bcl-2 expression was inhibited in the T/D group,and promoted by GYY4137 in the G-IP and G-IT groups.GYY4137,moderating these observed changes,displayed a more protective cffect with G-IT therapy than G-IP therapy.This study indicated that the efficacy of intratesticular therapy with GYY4137 is better than that of intraperitoneal therapy,which may provide a more valuable approach for testicular torsion therapy.

Effect of net carriers at the interconnection layer in tandem organic solar cells

Tandem cell with structure of indium tin oxide(ITO)/molybdenum oxide(MoO_(3))/fullerene(C60)/copper phthalocyanine(CuPc)/C60/tris-8-hydroxy-quinolinato aluminum(Alq_(3))/Al was fabricated to study the effect of net carriers at the interconnection layer. The open circuit voltage and short circuit current were found to be 1.15 V and 0.56 mA/cm^(2),respectively. Almost the same performance(1.05 V, 0.58 mA/cm^(2)) of tandem cell with additional recombination layer(ITO/MoO_(3)/C60/Alq_(3)/Al/Ag/MoO_(3)/CuPc/C60/Alq_(3)/Al) demonstrates that the carrier balance is more crucial than carrier recombination. The net holes at the interconnection layer caused by more carrier generation from the back cell on one hand would enhance the recombination with electrons from the front cell and on the other hand would quench the excitons produced in CuPc of the back cell.

High-temperature fatigue behavior of 15CrNbTi ferritic stainless steel

In order to investigate the high-temperature fatigue and fatigue-creep behavior of 15CrNbTi ferritic stainless steel at 800°C,fatigue tests without holding time in laboratory air and with 10 s holding time induced at maximum cyclic stress under argon atmosphere were conducted on an electrohydraulic servo fatigue testing machine.In addition,the morphologies of fatigue fracture surfaces were observed,and the precipitates and dislocation substructures were characterized.The experimental results show that the fatigue limit of 15CrNbTi ferritic stainless steel is 30 MPa at 800°C.The fatigue life of the experimental steel obviously decreases if holding time of 10 s is introduced at maximum cyclic stress.Under two test conditions,the fatigue cracks transgranularly initiate at the free surface of fatigue specimens and then propagate in a transgranular mode.It is dem on strated that three kinds of precipitates inclu ding(Nb,Ti)C phase,Fe2Nb phase and Fe3Nb3C phase can be observed in 15CrNbTi ferritic stainless steel,and the Fe2Nb and Fe3Nb3C phases are mainly precipitated during the fatigue tests.In the fatigue deformation area,both dislocation tangles and dislocation arrays are observed.Furthermore,the sub-grains which form during the cycling deformation with holding time of 10 s are also found.Moreover,the formation of sub-grains leads to the deterioration of the fatigue life of 15CrNbTi steel.

Efficient design of rotary traveling wave oscillator array via geometric programming

This paper presents an efficient method for globally optimizing and automating component sizing for rotary traveling wave oscillator arrays. The lumped equivalent model of transmission lines loaded by inverter pairs is evaluated and posynomial functions for oscillation frequency, power dissipation, phase noise, etc. are formulated using transmission line theory. The re- sulting design problem can be posed as a geometric programJning problem, which can be efficiently solved with a convex opti- mization solver. The proposed method can compute the global optima more efficiently than the traditional iterative scheme and various design problems can be solved with the same circuit model. The globally optimal trade-off curves between competing objectives are also computed to carry out robust designs and quickly explore the design space.