RESUMO
In order to investigate the modification of the surface structure of FePS3 via Ga+ ion irradiation, we study the effect of thickness and Raman spectrum of multilayer FePS3 irradiated for 0 µs, 30 µs, and 40 µs, respectively. The results demonstrate that the intensity ratio of characteristic Raman peaks are obviously related to the thickness of FePS3. After Ga+ ion irradiation, the FePS3 sample gradually became thinner and the Eu peak and Eg(v11) peak in the Raman spectrum disappeared and the peak intensity ratio of A1g(v2) with respect to A1g(v1) weakened. This trend becomes more apparent while increasing irradiation time. The phenomenon is attributed to the damage of bipyramid structure of [P2S6]4- units and the cleavage of the P-P bands and the P-S bands during Ga+ ion irradiation. The results are of great significance for improving the two-dimensional characteristics of FePS3 by Ga+ ion beam, including structural and optical properties, which pave the way of surface engineering to improve the performance of various two-dimensional layered materials via ion beam irradiation.
RESUMO
A monolayer-graphene-based concentric-double-rings (CDR) structure is reported to achieve broadband plasmon-induced transparency (PIT) on the strength of edge mode in the mid-infrared regime. The theoretical analysis and simulation results reveal that the structure designed here has two plasmonic resonance peaks at 39.1 and 55.4 THz, and a transparency window with high transmission amplitude at the frequency of 44.1 THz. Based on the edge mode coupling between neighbor graphene ribbons, PIT phenomenon is produced through the interference between different (bright and dark) modes. The frequency and bandwidth of the transparency window and slow light time could be effectively adjusted and controlled via changing geometrical parameters of graphene or applying different gate voltages. Additionally, this structure is insensitive to the polarization and incident angle. This work has potential application on the optical switches and slow light modulators.
RESUMO
Glial cell line-derived neurotrophic factor (GDNF) is a potential therapeutic protein on a variety of central nervous system diseases including ischemic stroke. However, GDNF is a large molecule that cannot cross the blood-brain barrier (BBB), which is still intact in the early hours after stroke when neural rescue is possible. PEP-1 protein transduction domain can deliver protein cargo across the cell membrane and the BBB. In the present study, we generated a novel fusion protein PEP-1-GDNF and examined whether PEP-1-GDNF is protective in focal cerebral ischemia. PEP-1-GDNF (200 µg/kg) or PBS was intravenously applied over 5 min immediately after reperfusion of 90 min transient middle cerebral artery occlusion (MCAO). After 28 days, rats were deeply anesthetized and decapitated. Behavioral tests were performed during this period. The results showed that PEP-1-GDNF significantly reduced the infarct volume and improved behavioral function. Further, PEP-1-GDNF promoted the cell proliferation and differentiation in the dentate gyrus of the hippocampus and attenuated ischemia-induced learning and memory damage.
