Planar nanoscale vacuum channel transistors based on resistive switching.

Resistance switching (RS) offers promising applications in a variety of areas. In particular, silicon oxide (SiOx) under RS can serve as electron sources in new types of miniature vacuum electron tubes. In this work, planar nanoscale vacuum channel transistors (NVCTs) with graphene electrodes and RS SiOxelectron sources were developed. In each RS-NVCT, the resistance between the ground and the gate underwent high-low-high transitions, which resulted from formation and subsequent rupture of Si conducting filaments. Electrons were emitted from the post-reset Si filaments and the current received by the collector (IC) was well controlled by the gate voltage (VG). The transfer characteristics reveal thatICwas quite sensitive toVGwhen RS occurred. WithVGsweeping from 0 to -20 V, the obtained subthreshold swing (SS) of 76 mV dec-1was quite close to the theoretical limit of the SS of a field effect transistor at room temperature (60 mV dec-1). The largest ON/OFF ratio was of the order of 106. The output characteristics of the devices indicate that the dependence ofICon the collector voltage (VC) weakened at highVCvalues. These results demonstrate the application potential of RS-NVCTs as either switching devices or amplifiers.

Efficient and Dense Electron Emission from a SiO2 Tunneling Diode with Low Poisoning Sensitivity.

We report a tunneling diode enabling efficient and dense electron emission from SiO2 with low poisoning sensitivity. Benefiting from the shallow SiO2 channel exposed to vacuum and the low electron affinity of SiO2 (0.9 eV), hot electrons tunneling into the SiO2 channel from the cathode of the diode are efficiently emitted into vacuum with much less restriction in both space and energy than those in previous tunneling electron sources. Monte Carlo simulations on the device performance show an emission efficiency as high as 87.0% and an emission density up to 3.0 × 105 A/cm2. By construction of a tunneling diode based on Si conducting filaments in electroformed SiO2, an emission efficiency up to 83.7% and an emission density up to 4.4 × 105 A/cm2 are experimentally realized. Electron emission from the devices is demonstrated to be independent of vacuum pressure from 10-4 to 10-1 Pa without poisoning.

Spin-decoupled excitation and wavefront shaping of structured surface waves via on-chip terahertz metasurfaces.

Surface waves (SWs) are of great importance in terahertz (THz) photonics applications due to their subwavelength properties. Hence, it is crucial to develop surface wavefront shaping techniques, which is urgent in modern information technologies. In this paper, a new scheme is proposed to realize SW excitation and spin-decoupled wavefront shaping with an ultracompact planar meta-device working in the THz range. The meta-device is composed of two parts: meta-atoms (in the center) and plasmonic metals (on the left and right sides). By carefully setting the geometry size and rotation angle of each meta-atom, the encoded spin-decoupled phase distributions for both left circularly polarized (LCP) and right circularly polarized (RCP) incident THz waves are determined. In this way, circularly polarized (CP) incident THz waves can be converted to SWs propagating along plasmonic metals with unique wavefront profiles, i.e., Bessel and focusing profiles. Full-wave simulations and THz near-field scanning experiments were performed to verify the functionalities of the meta-device, both of which are in great agreement with theoretical predictions. Our findings may provide more solutions to design THz integrated photonic devices and systems.

Efficacy of Intravitreal Injection of Filtered Modified Low-Dose Triamcinolone Acetonide and Ranibizumab on Pseudophakic Cystoid Macular Edema.

PURPOSE: To compare the visual and morphological effects between intravitreal injection of filtered modified 2 mg triamcinolone acetonide (TA) and 0. 5 mg ranibizumab in patients with pseudophakic cystoid macular edema (PCME). METHODS: A retrospective, interventional study was conducted from January 2015 to February 2020 involving patients with PCME after uneventful cataract surgery. A total of 25 patients (25 eyes) with PCME received an intravitreal injection of 0.22 µm filtered modified 2 mg TA, while 15 patients (15 eyes) received 0.5 mg ranibizumab injection. Central macular thickness (CMT), best-corrected visual acuity (BCVA), intraocular pressure (IOP), times of repeated injections, and other side effects were observed at 2 weeks, 1 month, 3 months, and 6 months after injection; then, the data were compared with preinjection information in each group and between the two groups. RESULTS: Both the TA and ranibizumab intravitreal injection can achieve improved BCVA and reduced CMT in patients with PCME (P < 0.05), with a trend toward greater improvement in the TA group, but the difference was only significant at 3 months (P < 0.05). IOP was in the normal range without any significant difference (P > 0.05). Thirty-three percent of patients in the ranibizumab group required repeated intravitreal injection compared to 4% in the TA group. Further stratified analysis showed that the better therapeutic effect of the TA group at 3 months after injection only existed in patients with diabetes mellitus (DM), while not in patients without DM. There was no repeat injection in the TA group and 12.5% in the ranibizumab group for patients without DM, while 16.7% in the TA group and 57.1% in the ranibizumab group required repeated injection for patients with DM, which had a significant difference (P < 0.05). CONCLUSION: Intravitreal injection of filtered modified 2 mg TA is safe, effective, and an inexpensive alternative to antivascular endothelial growth factor (anti-VEGF) agents for patients with PCME, especially for patients concurrently with DM. A large number of clinical randomized controlled studies along with long-term follow-up observations are needed.

Intracameral anti-VEGF injection for advanced neovascular glaucoma after vitrectomy with silicone oil tamponade.

AIM: To evaluate the effect of intracameral injection of conbercept for the treatment of advanced neovascular glaucoma (NVG) after vitrectomy with silicone oil tamponade. METHODS: Conbercept 0.5 mg/0.05 mL was injected into the anterior chamber of 5 eyes, which had developed advanced NVG after vitrectomy with silicone oil tamponade. Then, trabeculectomy with mitomycin C and pan-retinal photocoagulation (PRP) or extra-PRP were conducted within 2d. The follow-up time was 6mo. Best-corrected visual acuity (BCVA), intraocular pressure (IOP), neovascularization of iris (NVI) were recorded before and after treatment. RESULTS: Within 2d after injection, IOP control, and NVI regression were optimal for trabeculectomy. Hyphema occurred in one eye in the process of injection. But none of them present hyphema after trabeculectomy. At the end of follow-up time, all eyes had improved BCVA, well-controlled IOP, and completely regressed NVI. CONCLUSION: Intracameral injection of conbercept is safe and effective in the treatment of patients with advanced NVG after vitrectomy with silicone oil tamponade. Within 2d after injection is the optimal time window for trabeculectomy, which can maximally reduce the risk of perioperative hyphema.

Thin platelet-like COF nanocomposites for blood brain barrier transport and inhibition of brain metastasis from renal cancer.

Effective treatment of brain metastases is hindered by the blood-brain barrier (BBB) and the rapid development of resistance to drug therapy. Moreover, the clinical application of general formulations is hampered by biological barriers and biological elimination. To tackle this challenge, we report a feasible approach for the assembly of polymer-covalent organic framework (COF) nanocomposites into 150 nm thin platelets as a drug delivery vehicle for enhanced retention in brain tumours. Using intravital imaging, we demonstrate that these polymer-COF nanocomposites are able to traverse the BBB in mice and achieve direct tumour accumulation in intracranial orthotopic models of brain metastasis from renal cancer (BMRC). These nanocomposites can target brain tumour cells and respond to tumour microenvironmental characteristics, including acidic and redox conditions. Intracranial tumour acidity triggers the breakdown of the nanoassemblies to polymer-COF nanocomposites due to the presence of borate bonds. Furthermore, in vivo studies on the nanocomposites showed enhanced brain tumour-targeting efficiency and therapeutic effects compared to those of free-drug dosing. Mice treated with drug-loaded polymer-COF nanocomposites also show protection from systemic drug toxicity and improved survival, demonstrating the preclinical potential of this nanoscale platform to deliver novel combination therapies to BMRC and other central nervous system (CNS) tumours.