ABSTRACT
The valley polarization, induced by the magnetic proximity effect, in monolayer transition metal dichalcogenides (TMDCs), has attracted significant attention due to the intriguing fundamental physics. However, the enhancement and modulation of valley polarization for real device applications is still a challenge. Here, using first-principles calculations we investigate the valley polarization properties of monolayer TMDCs CrS2 and CrSe2 and how to enhance the valley polarization by constructing Janus CrSSe (with an internal electric field) and modulate the polarization in CrSSe by applying external electric fields. Janus CrSSe exhibits inversion symmetry breaking, internal electric field, spin-orbit coupling, and compelling spin-valley coupling. A magnetic substrate of the MnO2 monolayer can induce a modest magnetic moment in CrSe2, CrSe2, and CrSSe. Notably, the Janus structure with an internal electric field has a much larger valley p compared with its non-Janus counterparts. Moreover, the strength of valley polarization can be further modulated by applying external electric fields. These findings suggest that Janus materials hold promise for designing and developing advanced valleytronic devices.
ABSTRACT
The neurovascular unit (NVU) plays an essential role in regulating neurovascular coupling, which refers to the communication between neurons, glia, and vascular cells to control the supply of oxygen and nutrients in response to neural activity. Cellular elements of the NVU coordinate to establish an anatomical barrier to separate the central nervous system from the milieu of the periphery system, restricting the free movement of substances from the blood to the brain parenchyma and maintaining central nervous system homeostasis. In Alzheimer's disease, amyloid-ß deposition impairs the normal functions of NVU cellular elements, thus accelerating the disease progression. Here, we aim to describe the current knowledge of the NVU cellular elements, including endothelial cells, pericytes, astrocytes, and microglia, in regulating the blood-brain barrier integrity and functions in physiology as well as alterations encountered in Alzheimer's disease. Furthermore, the NVU functions as a whole, therefore specific labeling and targeting NVU components in vivo enable us to understand the mechanism mediating cellular communication. We review approaches including commonly used fluorescent dyes, genetic mouse models, and adeno-associated virus vectors for imaging and targeting NVU cellular elements in vivo.
Subject(s)
Alzheimer Disease , Mice , Animals , Alzheimer Disease/genetics , Endothelial Cells , Blood-Brain Barrier/physiology , Brain/diagnostic imaging , Brain/blood supply , Astrocytes/physiologyABSTRACT
A reasonable design of samples with efficient spatial separation for photoinduced electron-hole pairs toward the photocatalytic hydrogen evolution reaction (HER) has gained significant attention. Herein, a new C/MoS2@ZnIn2S4/Co3O4 composite with a core-shell structure is designed toward photocatalytic hydrogen production on C/MoS2 and Co3O4 dual electron collectors. Co3O4 nanoparticles as the co-catalyst would form a Schottky junction with ZnIn2S4 nanosheets while the C/MoS2 hollow core would form the step-scheme (S-scheme) heterojunction with ZnIn2S4 sheets, which provides a dual photogenerated electron transfer pathway during the light irradiation process. In addition, the unique core-shell architecture offers large contact interfaces favoring the exposure of rich active sites, which facilitated the separation and the transfer of charges. Consequently, all these factors endowed the C/MoS2@ZnIn2S4/Co3O4 composite with enhanced light absorption ability and an increased hydrogen evolution rate of 6.7 mmol·g-1·h-1 under 420 nm light irradiation, which is about 23.4- and 4.5-fold that of ZnIn2S4 and CMZ, respectively. This work offers a guideline for designing efficient composite photocatalysts toward the photocatalytic HER.
