Metasurfaces have become a rapidly growing field of research in recent years due to their exceptional abilities in light manipulation and versatility in ultrathin optical applications. They also ...significantly benefit from their simplified fabrication process compared to metamaterials and are promising for integration with on‐chip nanophotonic devices owing to their planar profiles. The recent progress in metasurfaces is reviewed and they are classified into six categories according to their underlying physics for realizing full 2π phase manipulation. Starting from multi‐resonance and gap‐plasmon metasurfaces that rely on the geometric effect of plasmonic nanoantennas, Pancharatnam–Berry‐phase metasurfaces, on the other hand, use identical nanoantennas with varying rotation angles. The recent development of Huygens' metasurfaces and all‐dielectric metasurfaces especially benefit from highly efficient transmission applications. An overview of state‐of‐the‐art fabrication technologies is introduced, ranging from the commonly used processes such as electron beam and focused‐ion‐beam lithography to some emerging techniques, such as self‐assembly and nanoimprint lithography. A variety of functional materials incorporated to reconfigurable or tunable metasurfaces is also presented. Finally, a few of the current intriguing metasurface‐based applications are discussed, and opinions on future prospects are provided.
Metasurfaces as two‐dimensional analogs of metamaterials are highly feasible for the realization of exceptional abilities for light molding beyond that offered by conventional planar interfaces. An overview of recent progress on metasurfaces from their fundamental theoretical background, physical realization, and fabrication, to potential practical applications such as wave plates, polarimetries, metalenses, metaholograms, and optical vortex converters is presented.
Disruption of the blood-brain barrier (BBB) is critical to initiation and perpetuation of disease in multiple sclerosis (MS). We report an interaction between oligodendroglia and vasculature in MS ...that distinguishes human white matter injury from normal rodent demyelinating injury. We find perivascular clustering of oligodendrocyte precursor cells (OPCs) in certain active MS lesions, representing an inability to properly detach from vessels following perivascular migration. Perivascular OPCs can themselves disrupt the BBB, interfering with astrocyte endfeet and endothelial tight junction integrity, resulting in altered vascular permeability and an associated CNS inflammation. Aberrant Wnt tone in OPCs mediates their dysfunctional vascular detachment and also leads to OPC secretion of Wif1, which interferes with Wnt ligand function on endothelial tight junction integrity. Evidence for this defective oligodendroglial-vascular interaction in MS suggests that aberrant OPC perivascular migration not only impairs their lesion recruitment but can also act as a disease perpetuator via disruption of the BBB.
The second harmonic generation (SHG) of vertical and planar split‐ring resonators (SRRs) that are broken centro‐symmetry configurations at the interface of metal surface and air is investigated. ...Strong interactions, better electromagnetic field confinements, and less leakage into the substrate for vertical SRRs are found. Experimental results show a 2.6‐fold enhancement of SHG nonlinearity, which is in good agreement with simulations and calculations. Demonstrations of 3D metastructures and vertical SRRs with strong SHG nonlinearity majorly result from magnetic dipole and electric quadrupole clearly provides potential applications for photonics and sensing.
A 3D‐structured, vertical split ring resonator (VSRR), not only establishes stronger field enhancement to boost the nonlinear efficiency but also can produce six different second harmonic generation (SHG) signals generated from a single VSRR. These demonstrations provide an additional dimension to improve the SHG efficiency and also to simplify the sophisticated predesign for nonlinear signal manipulation.
Metalenses: Advances and Applications Tseng, Ming Lun; Hsiao, Hui‐Hsin; Chu, Cheng Hung ...
Advanced optical materials,
September 18, 2018, Letnik:
6, Številka:
18
Journal Article
Metasurfaces, the 2D counterpart of artificial metamaterials, have attracted much attention because of their exceptional ability to manipulate the electromagnetic wave such as amplitude, phase, ...polarization, propagation direction, and so on. Different from conventional lenses, metalenses based on the metasurface optics are truly flat and compact and exhibit superior performance. In this report, recent progress in the development of metalenses is explored. First, the working principle and characteristics of metalenses are discussed. Then, it is described how the dispersion aberration in metalenses can be eliminated to make them suitable for being employed in a range of applications that are difficult or impossible for traditional lenses. In addition, various metalens‐based applications are introduced, including imaging, high spectral resolution spectroscopy, and multiplex color routing. Furthermore, a survey of reconfigurable and tunable metalenses is conducted. Finally, the report concludes by addressing future prospects of metalenses.
Metalenses have emerged as one of the most important applications of metasurfaces. This progress report surveys recent advances in the development of metalenses with discussions of their working principles and methods of chromatic dispersion control. State‐of‐the‐art on reconfigurable and tunable metalenses is also presented. Potential applications and future prospects of metalenses are addressed.
Oligodendrocytes myelinate axons in the central nervous system and develop from oligodndrocyte precursor cells (OPCs) that must first migrate extensively during brain and spinal cord development. We ...show that OPCs require the vasculature as a physical substrate for migration. We observed that OPCs of the embryonic mouse brain and spinal cord, as well as the human cortex, emerge from progenitor domains and associate with the abluminal endothelial surface of nearby blood vessels. Migrating OPCs crawl along and jump between vessels. OPC migration in vivo was disrupted in mice with defective vascular architecture but was normal in mice lacking pericytes. Thus, physical interactions with the vascular endothelium are required for OPC migration. We identify Wnt-Cxcr4 (chemokine receptor 4) signaling in regulation of OPC-endothelial interactions and propose that this signaling coordinates OPC migration with differentiation.
Although previous studies have investigated the relationship between fracture risk and type 2 diabetes (T2D), cohort studies that estimate composite osteoporosis risk are lacking. This retrospective ...cohort study sought to determine the risk of osteoporosis in Taiwanese patients with T2D. Patients diagnosed with T2D between 2002 and 2015 identified through the 2002 Taiwan Survey of Hypertension, Hyperglycemia, and Hyperlipidemia were included. A total of 1690 men and 1641 women aged ≥40 years linked to the National Health Insurance Research Database (NHIRD) were followed up to the end of 2015 to identify the incidences of osteoporosis through ICD9-CM codes for osteoporosis or osteoporotic fractures or usage of anti-osteoporotic agents according to Anatomical Therapeutic Chemical codes determined from NHIRD. The person year approach and Kaplan-Meier analysis were then used to estimate the incidences and cumulative event rates, whereas the Cox proportional hazard model was used to calculate adjusted hazard ratios (HR) for osteoporosis events. A total of 792 new osteoporosis events were documented over a median follow-up duration of 13.6 years. Participants with T2D had higher osteoporosis risk adjusted HR: 1.37, 95% confidence interval (CI): 1.11-1.69 compared with those without T2D. Subgroup analyses revealed that age had a marginally significant effect, indicating that T2D had a more pronounced effect on osteoporosis risk in younger population (<65 years old). No difference was found between patients stratified according to sex. In conclusion, T2D was significantly associated with increased osteoporosis risk, especially in younger participants.
Astrocytes are no longer seen as a homogenous population of cells. In fact, recent studies indicate that astrocytes are morphologically and functionally diverse and play critical roles in ...neurodevelopmental diseases such as Rett syndrome and fragile X mental retardation. This review summarizes recent advances in astrocyte development, including the role of neural tube patterning in specification and developmental functions of astrocytes during synaptogenesis. We propose here that a precise understanding of astrocyte development is critical to defining heterogeneity and could lead advances in understanding and treating a variety of neuropsychiatric diseases.
Diversified neurons are essential for sensorimotor function, but whether astrocytes become specialized to optimize circuit performance remains unclear. Large fast α-motor neurons (FαMNs) of spinal ...cord innervate fast-twitch muscles that generate peak strength. We report that ventral horn astrocytes express the inward-rectifying K+ channel Kir4.1 (a.k.a. Kcnj10) around MNs in a VGLUT1-dependent manner. Loss of astrocyte-encoded Kir4.1 selectively altered FαMN size and function and led to reduced peak strength. Overexpression of Kir4.1 in astrocytes was sufficient to increase MN size through activation of the PI3K/mTOR/pS6 pathway. Kir4.1 was downregulated cell autonomously in astrocytes derived from amyotrophic lateral sclerosis (ALS) patients with SOD1 mutation. However, astrocyte Kir4.1 was dispensable for FαMN survival even in the mutant SOD1 background. These findings show that astrocyte Kir4.1 is essential for maintenance of peak strength and suggest that Kir4.1 downregulation might uncouple symptoms of muscle weakness from MN cell death in diseases like ALS.
•Kir4.1 is upregulated in astrocytes around high-activity alpha motor neurons (MNs)•Astrocyte Kir4.1 KO caused decreased peak strength without alpha MN loss•ALS patient-derived astrocytes show cell-autonomous Kir4.1 downregulation•Astrocyte Kir4.1 regulates MN size through PI3K/mTOR/pS6 activation
Kelley et al. show that specialized astrocytes surrounding spinal cord fast α-motor neurons are critical to generate peak strength and that they are compromised by mutations in models of amyotrophic lateral sclerosis.
Although Small-to-Medium-sized-Enterprises (SMEs) frequently make vital contributions to both national and global economics and innovations, the relative influences of Open Innovation (OI) on SME ...performance is inconsistently argued in the literature. This study is set to fill this gap through an investigation of the details and dynamics of SMEs’ engagement in OI. Further, its impact on performance, through the perspective of knowledge networking, is examined. Specifically, this study investigates the relationships between OI activities, reverse-knowledge sharing, stakeholder relationship and SMEs performance in a context of numerous Vietnamese industries. Results revealed that OI activities are statistically insignificant when related to SMEs’ overall performance. However, it should be noted that OI indirectly affects SME performance through the mediation effect of reverse-knowledge sharing and the moderation effect of stakeholder relations. Practical implications and theoretical potential for future research are discussed.
Background and Purpose
Neutrophilic inflammation is a critical pathogenic factor in psoriasis. The therapeutic applicability of palbociclib, a cyclin‐dependent kinase 4 and 6 (CDK4/6) inhibitor ...clinically used to treat cancer, in the treatment of neutrophil‐associated psoriasis remains undefined. In this study, we evaluated the therapeutic potential and pharmacological effect of palbociclib on neutrophil‐associated psoriasiform dermatitis.
Experimental Approach
The anti‐inflammatory effects of palbociclib were determined in activated human neutrophils. The therapeutic feasibility of palbociclib in psoriasis was demonstrated in a mouse model of imiquimod‐induced psoriasiform dermatitis. The in vitro enzymatic assays and in silico analyses were used to identify the underlying pharmacological mechanisms.
Key Results
This study found that palbociclib inhibited neutrophilic inflammation, including superoxide anion generation, reactive oxygen species (ROS) formation, elastase degranulation and chemotactic responses. The mechanistic studies identified that the anti‐inflammatory effects of palbociclib involved the targeting of phosphatidylinositol 3‐kinase (PI3K) but not CDK4/6 in human neutrophils. Palbociclib preferentially targeted the p110δ catalytic subunit of PI3K and thereby blocked signalling via the PI3K/protein kinase B (Akt) pathway. Furthermore, topical application of palbociclib significantly ameliorated imiquimod‐induced psoriasiform dermatitis in mice, including psoriatic symptoms, neutrophil infiltration, Akt activation and cytokine up‐regulation.
Conclusions and Implications
This is the first study to demonstrate that palbociclib can potentially be used to treat neutrophil‐associated psoriasiform dermatitis through the targeting of neutrophilic PI3K activity. Our findings prompt further research to explore the potential of palbociclib and PI3K in psoriasis and other inflammatory diseases.
PDF
