Dynamic changes in neuronal autophagy and apoptosis in the ischemic penumbra following permanent ischemic stroke

The temporal dynamics of neuronal autophagy and apoptosis in the ischemic penumbra following stroke remains unclear.Therefore,in this study,we investigated the dynamic changes in autophagy and apoptosis in the penumbra to provide insight into potential therapeutic targets for stroke.An adult Sprague-Dawley rat model of permanent ischemic stroke was prepared by middle cerebral artery occlusion.Neuronal autophagy and apoptosis in the penumbra post-ischemia were evaluated by western blot assay and immunofluorescence staining with antibodies against LC3-Ⅱ and cleaved caspase-3,respectively.Levels of both LC3-Ⅱ and cleaved caspase-3 in the penumbra gradually increased within 5 hours post-ischemia.Thereafter,levels of both proteins declined,especially LC3-Ⅱ.The cerebral infarct volume increased slowly 1–4 hours after ischemia,but subsequently increased rapidly until 5 hours after ischemia.The severity of the neurological deficit was positively correlated with infarct volume.LC3-Ⅱ and cleaved caspase-3 levels were high in the penumbra within 5 hours after ischemia,and after that,levels of these proteins decreased at different rates.LC3-Ⅱ levels were reduced to a very low level,but cleaved caspase-3 levels remained high 72 hours after ischemia.These results indicate that there are temporal differences in the activation status of the autophagic and apoptotic pathways.This suggests that therapeutic targeting of these pathways should take into consideration their unique temporal dynamics.

Crystallization kinetics and magnetization behavior of RE_(3.5)Fe_(66.5)Co_(10)B_(20)(RE=Pr, Nd) nanocomposite ribbons

The influence of hard magnetic phase on the crystallization kinetics and magnetization behavior in nanocomposite RE3.5Fe66.5Co10B20（RE = Pr, Nd） ribbons prepared by melt-spinning was studied. Differential scanning calorimeter（DSC） measurement of the as-cast meltspun amorphous ribbons during the crystallization process shows that precipitation energy of Pr2Fe14 B phase is higher than that for Nd2Fe14 B phase, confirmed by X-ray diffraction（XRD） patterns. It can be explained by the different radii of Pr and Nd atoms. Scanning electron microscopy（SEM）images indicate that the average grain size in Pr3.5Fe66.5Co10B20 ribbon is smaller than that in Nd3.5Fe66.5Co10B20,resulting in an enhancement of exchange coupling between hard and soft phases. It is responsible for the better hard magnetic properties in Pr3.5Fe66.5Co10B20. In addition, the process of magnetization reversal of nanocomposite RE3.5Fe66.5Co10B20（RE = Pr, Nd） ribbons was discussed in detail by the recoil loops.

Magnetization reversal behavior and first-order reversal curve diagrams in high-coercivity Zr-doped α-Fe/Nd_(2)Fe_(14)B nanocomposite alloys

In the present work,the magnetization reversal behavior for the melt spinning(Nd_(0.8)Ce_(0.2))_(2)Fe_(12)Co_(2-x)Zr_(x)B(x=0,0.5)permanent alloys with high coercivity was investigated by analyzing the hysteresis curves and the recoil loops.Compared to the Zr-free alloy,the Zr-doped sample obtains higher magnetic properties:coercivity of H_(cj)=650.5 kA·m^(-1),squareness of H_(k)/H_(cj)=0.76 and maximum energy product of(BH)_(max)=131.0 kJ·m^(-3).The first-order reversal curves(FORCs)analysis was taken to identify optimal conditions of exchange coupling for the Zr-free and Zr-doped alloys.The coercivity mechanism of theα-Fe/Nd_(2)Fe_(14)B nanocomposite alloys was analyzed by the angular dependence of the coercive field as measured for the Zr-doped sample.The results show that the magnetic reverse process of the Zr-doped sample can be explained by the pinning model.