Calculation and experimental study on heating temperature field of super-high strength aluminum alloy thick plate

Stepped heating treatment has been applied to aluminum alloy thick plate to improve the mechanical performance and corrosion resistance.Accurate temperature control of the plate is the difficulty in engineering application.The heating process,the calculation of surface heat transfer coefficient and the accurate temperature control method were studied based on measured heating temperature for the large-size thick plate.The results show that,the temperature difference between the surface and center of the thick plate is small.Based on the temperature uniformity,the surface heat transfer coefficient was calculated,and it is constant below300°C,but grows greatly over300°C.Consequently,a lumped parameter method(LPM)was developed to predict the plate temperature.A stepped solution treatment was designed by using LPM,and verified by finite element method(FEM)and experiments.Temperature curves calculated by LPM and FEM agree well with the experimental data,and the LPM is more convenient in engineering application.

Vancomycin-induced thrombocytopenia in endocarditis:A case report and review of literature

BACKGROUND Thrombocytopenia is a serious complication in the medical practice of numerous drugs.Vancomycin is frequently used for the prophylaxis and treatment of suspected or identified methicillin-resistant positive infections.Several cases with vancomycin-induced thrombocytopenia(VIT)have been reported.However,these have rarely been extensively reviewed.The present report describes a case of VIT in endocarditis,and reviews all VIT cases reported in the literature.CASE SUMMARY A 26-year-old male diagnosed with infective endocarditis was admitted.The patient was treated with multiple drugs,including vancomycin,which was initially intravenously given at 1000 mg every 12 h and subsequently at 500 mg every 8 h on day 3.On day 11,the platelet count decreased to 51×10^(9)/L,vancomycin was switched to 500 mg every 12 h,and platelet transfusion was given.On day 17,the platelet count dropped to 27×10^(9)/L,and platelet transfusion was administered again.On day 23,vancomycin was adjusted to 500 mg every 8 h as the trough concentration dropped to the minimum effective concentration.On day 33,the platelet count declined to approximately 40×10^(9)/L.After platelet transfusion,the platelet count rebounded to 90×10^(9)/L on day 35 but dropped again to 42×10^(9)/L on day 43.Based on the time-to-platelet count curve and Naranjo’s Adverse Drug Reaction Probability Scale score,VIT was suspected.After vancomycin discontinuation and platelet transfusion,the platelet count gradually normalized.CONCLUSION The diagnosis of VIT can be achieved through the time-to-platelet count curve and Naranjo’s Adverse Drug Reaction Probability Scale score.The platelet count cannot be normalized simply by platelet transfusion alone,and vancomycin discontinuation is essential.

Progress on elliptical magnetic skyrmions

Magnetic skyrmions,the topological spin textures firstly observed in chiral magnets,have aroused huge interest due to their emergent electromagnetism and potential applications in spintronics.Over the last decade,significant efforts have been devoted to skyrmion generation,stabilization,and dynamics.In most cases,the theoretical and experimental investigations have been performed in the materials where the skyrmions have a circular shape.As we know,magnetic anisotropy(K_(u))and Dzyaloshinskii-Moriya interaction(DMI)play key roles in the stabilization of the skyrmions in chiral magnets.Therefore,modifying the Kand DMI provide new degrees of freedom for studying the related physics and applications of skyrmions in addition to engineering their energetics and sizes.In this review,the latest progress on the study of the anisotropic deformation of magnetic skyrmions(i.e.,elliptical magnetic skyrmions)is summarized.The physical origins and important advantages of elliptical magnetic skyrmions are mainly focused on.This review gives an insight into the understanding of the physical mechanisms of elliptical magnetic skyrmion-hosting systems.

Excellent energy storage properties realized in novel BaTiO_(3)-based lead-free ceramics by regulating relaxation behavior

BaTiO_(3)(BT)has attracted extensive attention among advanced lead-free ferroelectric materials due to its unique dielectric and ferroelectric properties.However,the enormous remanent polarization and coercive field severely impede the improvement of its energy storage capabilities.Here,the BaTiO_(3)e-Bi(Zn_(0.5)Hf_(0.5))O_(3)(BT-BZH)ceramics with high breakdown field strength and remarkable relaxation characteristics can be obtained by introducing the composite component BZH in BT to regulate the phase structure and grain size of the ceramics.The findings demonstrate that the improvement of energy storage performance is related to the increase of relaxation behavior.A large energy storage density(Wrec~3.62 J/cm^(3))along with superior energy storage efficiency(h~88.5%)is achieved in 0.88BT-0.12BZH relaxor ceramics only at 240 kV/cm.In addition,the sample suggests superior thermal stability and frequency stability within 25e115℃and 1e500 Hz,respectively.Furthermore,the outstanding chargedischarge properties with an ultrafast discharge time(100 ns),large discharged energy density(1.2 J/cm^(3)),impressive current density(519.4 A/cm^(2))and power density(31.1 MW/cm^(3))under the electric field of 120 kV/cm are achieved in studied ceramics.The excellent energy storage performance of BT-BZH ceramics provides a promising platform for the application of lead-free energy-storage materials.

Composition-tailor induced electrocaloric effect near room temperature in(Pb,Ba)HfO_(3)films

More and more researchers start to pay attention to the electrocaloric temperature change(DT)in polar materials,which is caused by an applied electric field.In this paper,Ba-doped PbHfO_(3)(PBH)films were prepared by sol-gel method.Their components,microstructures,dielectric polarization and electro-caloric effects(ECEs)were investigated.With the addition of Ba^(2+),PBH films went from antiferroelectric(AFE)to ferroelectric(FE).At the same time,their dielectric peaks shifted toward lower temperature.The maximum DT obtained in Pb_(0.8)Ba_(0.2)HfO_(3)FE film is 41.1 K,which is an order of magnitude larger than PbHfO_(3)film(△T<4 K at 50℃)and Pb_(0.9)Ba_(0.1)HfO_(3)film(△T<4 K at 120℃).In order to explain this phenomenon,the Landau-Devonshire theory was adopted.Our analysis shows that the rapid variation of energy barrier height near the phase transition temperature is beneficial to obtain large polarization change and high△T,which is needed in solid-state cooling devices.

Superior Energy and Power Density Realized in Pb(Hf_(1-x)Ti_(x))O_(3) System at Low Electric Field

The development of antiferroelectric materials with large energy density and fast discharge speed makes dielectric capacitors possess great prospects for applications in pulsed power technology.Here,the PbHfO_(3)-based ceramics with compositions of Pb(Hf_(1-x)Ti_(x))O_(3)(PHT,0.01≤x≤0.05)were synthesized,and their antiferroelectricity and phase transition behavior were studied.According to the tests of x-ray diffraction,dielectric spectrum,and polarization-electric field hysteresis loops,PHT ceramics gradually transition from an orthorhombic symmetric antiferroelectric phase to a hexagonal symmetric ferroelectric phase at room temperature as Ti^(4+)concentration increases.The forward phase switching field of antiferroelectric to ferroelectric phase transition can be markedly regulated by the introduction of Ti^(4+),and the optimal energy storage performance was obtained in Pb(Hf_(0.98)Ti_(0.02))O_(3) ceramics with a large recoverable energy storage density of Wrec~4.15 J/cm^(3) and efficiency ofη~65.3%only at a low electric field of 190 kV/cm.Furthermore,the outstanding charge-discharge properties with an ultrafast discharge time(71 ns),remarkable discharged energy density(2.84 J/cm^(3)),impressive current density(1,190 A/cm^(2)),and ultrahigh power density(101 MW/cm^(3))at a low electric field of 170 kV/cm were obtained in studied ceramics.The excellent energy storage performance of PHT ceramics provides a promising platform for the application of dielectric capacitors.

Protective effect of bone marrow mesenchymal stem cell-derived exosomes against the reproductive toxicity of cyclophosphamide is associated with the p38MAPK/ERK and AKT signaling pathways

Spermatogenic dysfunction caused by cyclophosphamide(CP)chemotherapy has seriously influenced the life quality of patients.Unfortunately,treatments for CP-induced testicular spermatogenic dysfunction are limited,and the molecular mechanisms are not fully understood.For the first time,here,we explored the effects of bone marrow mesenchymal stem cell-derived exosomes(BMSC-exos)on CP-induced testicular spermatogenic dysfunction in vitro and in vivo.BMSC-exos could be taken up by spermatogonia(GC1-spg cells).CP-injured GC1-spg cells and BMSC-exos were cocultured at various doses,and then,cell proliferation was measured using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide(MTT)assay.In addition,photophosphorylation of extracellular-regulated kinase(ERK),p38 mitogen-activated protein kinase(p38MAPK),and protein kinase B(AKT)proteins was evaluated by western blotting as well as apoptosis in GC1-spg cells measured using flow cytometry.Treatment with BMSC-exos enhanced cell proliferation and reduced apoptosis of CP-injured GCI-spg cells.Phosphorylated levels of ERK,AKT,and p38MAPK proteins were reduced in CP-injured spermatogonia when co-treated with BMSC-exos,indicating that BMSC-exos acted against the reproductive toxicity of CP via the p38MAPK/ERK and AKT signaling pathways.In experiments in vivo,CP-treated rats received BMSC-exos by injection into the tail vein,and testis morphology was compared between treated and control groups.Histology showed that transfusion of BMSC-exos inhibited the pathological changes in CP-injured testes.Thus,BMSC-exos could counteract the reproductive toxicity of CP via the p38MAPK/ERK and AKT signaling pathways.The findings provide a potential treatment for CP-induced male spermatogenic dysfunction using BMSC-exos.