A Fully Metaoptical Zoom Lens with a Wide Range.

Metalenses are typically designed for a fixed focal length, restricting their functionality to static scenarios. Various methods have been introduced to achieve the zoom function in metalenses. These methods, however, have a very limited zoom range, or they require additional lenses to achieve direct imaging. Here, we demonstrate a zoom metalens based on axial movement that performs both the imaging and the zoom function. The key innovation is the use of a polynomial phase profile that mimics an aspheric lens, which allows an extended depth of focus, enabling a large zoom range. Experimental results show that this focal length variation, combined with the extended depth of focus, translates into an impressive zoom range of 11.9× while maintaining good imaging quality. We see applications for such a zoom metalens in surveillance cameras of drones or microrobots to reduce their weight and volume, thus enabling more flexible application scenarios.

D-2-HG Inhibits IDH1mut Glioma Growth via FTO Inhibition and Resultant m6A Hypermethylation.

IDH1mut gliomas produce high levels of D-2-hydroxyglutarate (D-2-HG), an oncometabolite capable of inhibiting α-ketoglutarate-dependent dioxygenases critical to a range of cellular functions involved in gliomagenesis. IDH1mut gliomas also exhibit slower growth rates and improved treatment sensitivity compared with their IDH1wt counterparts. This study explores the mechanism driving apparent reduced growth in IDH1mut gliomas. Specifically, we investigated the relationship between IDH1mut and the RNA N6-methyladenosine (m6A) demethylases FTO and ALKBH5, and their potential for therapeutic targeting. We investigated the role of D-2-HG and m6A in tumor proliferation/viability using glioma patient tumor samples, patient-derived gliomaspheres, and U87 cells, as well as with mouse intracranial IDH1wt gliomasphere xenografts. Methylation RNA immunoprecipitation sequencing (MeRIP-seq) RNA sequencing was used to identify m6A-enriched transcripts in IDH1mut glioma. We show that IDH1mut production of D-2-HG is capable of reducing glioma cell growth via inhibition of the m6A epitranscriptomic regulator, FTO, with resultant m6A hypermethylation of a set of mRNA transcripts. On the basis of unbiased MeRIP-seq epitranscriptomic profiling, we identify ATF5 as a hypermethylated, downregulated transcript that potentially contributes to increased apoptosis. We further demonstrate how targeting this pathway genetically and pharmacologically reduces the proliferative potential of malignant IDH1wt gliomas, both in vitro and in vivo. Our work provides evidence that selective inhibition of the m6A epitranscriptomic regulator FTO attenuates growth in IDH1wt glioma, recapitulating the clinically favorable growth phenotype seen in the IDH1mut subtype. SIGNIFICANCE: We show that IDH1mut-generated D-2-HG can reduce glioma growth via inhibition of the m6A demethylase, FTO. FTO inhibition represents a potential therapeutic target for IDH1wt gliomas and possibly in conjunction with IDH1mut inhibitors for the treatment of IDH1mut glioma. Future studies are necessary to demonstrate the role of ATF5 downregulation in the indolent phenotype of IDH1mut gliomas, as well as to identify other involved gene transcripts deregulated by m6A hypermethylation.

Robust and Corrosion-Resistant Overall Water Splitting Electrode Enabled by Additive Manufacturing.

Electrolysis of water has emerged as a prominent area of research in recent years. As a promising catalyst support, copper foam is widely investigated for electrolytic water, yet the insufficient mechanical strength and corrosion resistance render it less suitable for harsh working conditions. To exploit high-performance catalyst supports, various metal supports are comprehensively evaluated, and Ti6 Al4 V (Ti64) support exhibited outstanding compression and corrosion resistance. With this in mind, a 3D porous Ti64 catalyst support is fabricated using the selective laser sintering (SLM) 3D printing technology, and a conductive layer of nickel (Ni) is coated to increase the electrical conductivity and facilitate the deposition of catalysts. Subsequently, Co0.8 Ni0.2 (CO3 )0.5 (OH)·0.11H2 O (CoNiCH) nanoneedles are deposited. The resulting porous Ti64/Ni/CoNiCH electrode displayed an impressive performance in the oxygen evolution reaction (OER) and reached 30 mA cm-2 at an overpotential of only 200 mV. Remarkably, even after being compressed at 15.04 MPa, no obvious structural deformation is observed, and the attenuation of its catalytic efficiency is negligible. Based on the computational analysis, the CoNiCH catalyst demonstrated superior catalytic activity at the Ni site in comparison to the Co site. Furthermore, the electrode reached 30 mA cm-2 at 1.75 V in full water splitting conditions and showed no significant performance degradation even after 60 h of continuous operation. This study presents an innovative approach to robust and corrosion-resistant catalyst design.

Design and fabrication of biomimicking radially graded scaffolds via digital light processing 3D printing for bone regeneration.

Scaffolds are an essential component in bone tissue engineering (BTE). However, most of the current BTE scaffolds are homogeneous structures and do not resemble the graded architectures of native bone. In the current study, four types of biomimicking scaffold designs based on gyroid (G) and primitive (P) units with radially graded pore sizes were devised, and scaffolds of these designs with two porosity groups (65 vol% and 75 vol%) were fabricated via digital light processing (DLP) 3D printing using biphasic calcium phosphate (BCP). Scaffolds of the gyroid-gyroid (G-G) design displayed better dimensional accuracy, compressive property, and cell proliferation rate than gyroid-primitive (G-P), primitive-gyroid (P-G), and primitive-primitive (P-P) scaffolds. Subsequently, graded G-G scaffolds with different porosities were fabricated and the relationship between compressive strength and porosity was determined. Furthermore, the sintered BCP bioceramics fabricated via current manufacturing process exhibited excellent biocompatibility and bioactivity, indicating their high potential for BTE.

Imaging through scattering media under strong ambient light interference via the lock-in process.

Scattered light imaging techniques leveraging memory effects have been extensively investigated, yet most approaches are limited to operating in predominantly dark environments. The introduction of additional optical noise disrupts the fine structure of the original speckle pattern, undermining spatial correlation and resulting in imaging failure. In this study, we present a high-performance imaging method that integrates a lock-in process to overcome this limitation. Our experimental results demonstrate that the proposed technique enables successful imaging of targets in low signal-to-background ratio (SBR) environments, even at SBR levels as low as -28.0 dB. Furthermore, the method allows for the directional separation of targets with distinct modulation frequencies. This innovative approach has the potential to significantly expand the applicability of scattering imaging techniques by eliminating the constraints of dark field environments, thereby enhancing the convenience of in vivo microscopy and daytime astronomical observations.

Directional and Eye-Tracking Light Field Display with Efficient Rendering and Illumination.

Current efforts with light field displays are mainly concentrated on the widest possible viewing angle, while a single viewer only needs to view the display in a specific viewing direction. To make the light field display a practical practice, a super multi-view light field display is proposed to compress the information in the viewing zone of a single user by reducing the redundant viewpoints. A quasi-directional backlight is proposed, and a lenticular lens array is applied to achieve the restricted viewing zone. The eye-tracking technique is applied to extend the viewing area. Experimental results show that the proposed scheme can present a vivid 3D scene with smooth motion parallax. Only 16.7% conventional light field display data are required to achieve 3D display. Furthermore, an illumination power of 3.5 watt is sufficient to lighten a 31.5-inch light field display, which takes up 1.5% of the illumination power required for planar display of similar configuration.

Contribution of the stereoscopic representation of motion-in-depth during visually guided feedback control.

Considerable studies have focused on the neural basis of visually guided tracking movement in the frontoparallel plane, whereas the neural process in real-world circumstances regarding the influence of binocular disparity and motion-in-depth (MID) perception is less understood. Although the role of stereoscopic versus monoscopic MID information has been extensively described for visual processing, its influence on top-down regulation for motor execution has not received much attention. Here, we orthogonally varied the visual representation (stereoscopic versus monoscopic) and motion direction (depth motion versus bias depth motion versus frontoparallel motion) during visually guided tracking movements, with simultaneous functional near-infrared spectroscopy recordings. Results show that the stereoscopic representation of MID could lead to more accurate movements, which was supported by specific neural activity pattern. More importantly, we extend prior evidence about the role of frontoparietal network in brain-behavior relationship, showing that occipital area, more specifically, visual area V2/V3 was also robustly involved in the association. Furthermore, by using the stereoscopic representation of MID, it is plausible to detect robust brain-behavior relationship even with small sample size at low executive task demand. Taken together, these findings highlight the importance of the stereoscopic representation of MID for investigating neural correlates of visually guided feedback control.

Harnessing the plenoptic function for a directionally illuminated autostereoscopic display.

The plenoptic function is ideal to describe three-dimensional displays. We propose and demonstrate in this work that plenoptic function is a particularly suitable scenario in the directionally illuminated autostereoscopic display. Guided by this function, backlight structures and functional thin films are designed and applied for wave-vector and amplitude control so that homogeneous viewing is achieved in large viewing volume while display functionality with optical focusing and diverting can be fulfilled. The demonstration of high-quality displays by cloaking various optical defects in an otherwise severely distorted radiance distribution introduced by lens array is presented. We conclude that the scenario adopted in this work is immediately applicable to enhance general performance for autostereoscopy.

Far-Field and Non-Intrusive Optical Mapping of Nanoscale Structures.

Far-field high-density optics storage and readout involve the interaction of a sub-100 nm beam profile laser to store and retrieve data with nanostructure media. Hence, understanding the light-matter interaction responding in the far-field in such a small scale is essential for effective optical information processing. We present a theoretical analysis and an experimental study for far-field and non-intrusive optical mapping of nanostructures. By a comprehensive analytical derivation for interaction between the modulated light and the target in a confocal laser scanning microscopy (CLSM) configuration, it is found that the CLSM probes the local density of states (LDOSs) in the far field rather than the sample geometric morphology. With a radially polarized (RP) light for illumination, the far-field mapping of LDOS at the optical resolution down to 74 nm is obtained. In addition, it is experimentally verified that the target morphology is mapped only when the far-field mapping of LDOS coincides with the geometric morphology, while light may be blocked from entering the nanostructures medium with weak or missing LDOS, hence invalidating high-density optical information storage and retrieval. In this scenario, nanosphere gaps as small as 33 nm are clearly observed. We further discuss the characterization for far-field and non-intrusive interaction with nanostructures of different geometric morphology and compare them with those obtainable with the projection of near-field LDOS and scanning electronic microscopic results.

A novel clinical dynamic stereopsis assessment based on autostereoscopic display system.

Background: Although it is recognized that dynamic stereopsis is vital in daily life, there is still room for improvement in assessment methods. A novel clinical dynamic stereopsis assessment method was created based on an autostereoscopic display system that did not require additional auxiliary glasses. This study evaluated the optical parameters and clinical performance of the autostereoscopic display system for clinical dynamic stereopsis assessment. Methods: The autostereoscopic dynamic stereopsis assessment device was based on a directional backlight technology. Experiment 1 was performed under the same environmental conditions to compare luminance, crosstalk, and spectrum between the autostereoscopic dynamic stereopsis assessment device and the conventional dynamic random-dot stereopsis measuring instrument. Experiment 2 was an observational, analytic, cross-sectional study involving 135 healthy participants, each of whom was asked to complete measurements on both the autostereoscopic and conventional devices in random order. Stereo acuity, operating time, acceptance, and visual fatigue scores were recorded for clinical evaluation. Results: The autostereoscopic device had brighter luminance (139 and 140 cd/m2 for 2 eyes, respectively), lower crosstalk (4.50% for both eyes), and higher color restoration degree than those of the conventional instrument. Clinically, the novel dynamic stereopsis assessment was as accurate as the traditional method [170" (0.00") and 170" (0.00") respectively; P=0.317], and with more efficiency (166±58.9 and 298±116 s, respectively; P<0.001), higher acceptance (3.36±0.93 and 2.02±0.59 points, respectively; P<0.001), lesser fatigue (0.27±0.46 and 0.73±0.66 points, respectively; P<0.001). The autostereoscopic dynamic stereopsis assessment device with brighter luminance, lower crosstalk, and higher color restoration degree was more effective than the traditional instrument at displaying dynamic clues for clinical dynamic stereopsis assessment. Furthermore, its high-quality image and user-friendly interface provided accurate assessment results in all 3 dynamic stereopsis assessment task conditions, with a higher level of acceptance and lesser visual fatigue, than the traditional assessment method. Conclusions: The autostereoscopic device has excellent functions in both optical parameters and clinical performance, and therefore has the potential to be applied and popularized in future assessments.

RGB Achromatic Metalens Doublet for Digital Imaging.

Chromatic aberration is a major challenge faced by metalenses. Current methods to achieve broadband achromatic operation in metalenses usually suffer from limited size, numerical aperture, and working bandwidth due to the finite group delay of meta-atoms, thus restricting the range of practical applications. Multiwavelength achromatic metalenses can overcome those limitations, making it possible to realize larger numerical aperture (NA) and sizes simultaneously. However, they usually require three layers, which increases their fabrication complexity, and have only been demonstrated in small sizes, with low numerical aperture and modest efficiencies. Here, we demonstrate a 1 mm diameter red-green-blue achromatic metalens doublet with a designed NA of 0.8 and successfully apply the metalens in a digital imaging system. This work shows the potential of the doublet metasurfaces, extending their applications to digital imaging systems such as digital projectors, virtual reality glasses, high resolution microscopies, etc.

Realization of inversely designed metagrating for highly efficient large angle beam deflection.

Directional emission source is one of the key components for multiple-view three-dimensional display. It is hard to achieve high efficiency and large deflection angle direction sources via geometric optics due to the weak confinement of light. The metasurface especially metagrating provides a promising method to control light effectively. However, the conventional forward design methods for metasurface are inherently limited by insufficient control of Bloch modes, which causes a significant efficiency drop at a large deflection angle. Here, we obtained high efficiency large deflection angle metagratings by realizing the constructive interferences among the propagation Bloch modes and enhancing the outcoupling effect at the desired diffraction order. The grating structures that support the coupling of Bloch modes were designed by an inverse design method for different incident wavelengths, and the total phase response of a supercell can be tailored. For a red (620 nm) incident light, the theoretical deflection efficiency of a silicon metagrating can be higher than 80% from 30° to 80°. The experimental deflection efficiency can achieve 86.43% for a 75° deflection metagrating. The matched simulation and experimental results strongly support the reliability of developed algorithm. Our inverse design approach could be extended to the green (530 nm) and blue (460 nm) incident light with titanium dioxide metagratings, with theoretical deflection efficiency of over 80% in a large deflection angle range of 30° to 80°. Considering the multiple visible wavelength deflection capability, the developed algorithm can be potentially applied for full color three-dimensional display, and other functional metagrating devices based on different dielectric materials.

Nano-Hydroxyapatite Bone Scaffolds with Different Porous Structures Processed by Digital Light Processing 3D Printing.

The morphologies and structures of the scaffold have a significant influence on their mechanical and biological properties. In this work, different types of porous structures: Triply periodic minimal surface-Schwarz primitive (P), body-centered cubic, and cubic pore-shaped (CPS) hydroxyapatite scaffolds with ~70% porosity were fabricated through digital light processing (DLP) 3D printing technology. The compressive properties and in vitro cell evaluations such as cell proliferation and attachment morphology of these scaffolds were systematically compared. The results showed that the CPS scaffolds exhibited the highest compressive strength (~22.5 MPa) and modulus (~400 MPa). In addition, the CPS scaffolds also performed the most active cell metabolisms as compared to other two structures, which may account for the larger pore size and smaller curvature of the substrate. This study provides a general guidance for the fabrication and selection of porous bone scaffolds processed by DLP 3D printing.

Accurate measurement of virtual image distance for near-eye displays based on auto-focusing.

Virtual reality (VR) and augmented reality (AR) are able to project virtual images to human eyes at a certain depth distance. This virtual image distance can be adjusted by controlling the diopter of the near-eye display. However, it is difficult to measure accurately and continuously since this virtual image distance spans a large range. In this work, we propose a method to accurately determine the virtual image distance of commercial VR/AR equipment. The measurement apparatus is built and calibrated to validate the feasibility. The focal distance of the focus-tunable lens can be automatically adjusted via a step motor by cooperating with the image sharpness analyzing program. Compared with other proposed methods, ours provides an effective means to achieve high accuracy, a wide and continuous testing range, and automatic evaluation of virtual image distance for compact near-eye displays.

Coeloglossum viride var. bracteatum extract attenuates staurosporine induced neurotoxicity by restoring the FGF2-PI3K/Akt signaling axis and Dnmt3.

We previously demonstrated the antioxidant activity of Coeloglossum viride var. bracteatum extract (CE) in rat cortical neurons and in mice with chemically induced cognitive impairment. In this work, we established a staurosporine (STS)-induced toxicity model to decipher the neuroprotective mechanisms of CE. We found that CE protected cell viability and neurite integrity in STS-induced toxicity by restoring the levels of FGF2 and its associated PI3K/Akt signaling axis. LY294002, a pan-inhibitor of PI3K, antagonized the activity of CE, although its-mediated restoration of FGF2 was unaffected. In addition, CE restored levels of Bcl-2/Caspase-3, PKCα/CaM pathway, and Dnmt3a and Dnmt3b, two methyltransferases that contribute to de novo DNA methylation. The Dnmts inhibitor 5-azacytidine impaired CE-mediated restoration of Dnmt3 or CaM, as well as the transition of DNA methylation status on the Dnmt3 promoter. These results reveal potential mechanisms that could facilitate the study and application of CE as a neuroprotective agent.

Metalenses: from design principles to functional applications.

Lens is a basic optical element that is widely used in daily life, such as in cameras, glasses, and microscopes. Conventional lenses are designed based on the classical refractive optics, which results in inevitable imaging aberrations, such as chromatic aberration, spherical aberration and coma. To solve these problems, conventional imaging systems impose multiple curved lenses with different thicknesses and materials to eliminate these aberrations. As a unique photonic technology, metasurfaces can accurately manipulate the wavefront of light to produce fascinating and peculiar optical phenomena, which has stimulated researchers' extensive interests in the field of planar optics. Starting from the introduction of phase modulation methods, this review summarizes the design principles and characteristics of metalenses. Although the imaging quality of existing metalenses is not necessarily better than that of conventional lenses, the multi-dimensional and multi-degree-of-freedom control of metasurfaces provides metalenses with novel functions that are extremely challenging or impossible to achieve with conventional lenses.

Non-invasive optical imaging using the extension of the Fourier-domain shower-curtain effect.

Optical imaging for non-self-luminous objects surrounded by complex scattering environments is scientifically challenging and technologically important. We propose a non-invasive imaging method by externally sending the illuminating light through the scattering medium and by detecting and analyzing the speckle patterns. The imaging of the object is recovered by extending the application scope of the Fourier-domain shower-curtain effect. It is found that the imaging depth is substantially extended and that faster imaging restoration is realized with the improved illumination scheme assisted with optical lenses, hence making it possible to apply the non-invasive optical imaging technique for practical applications.

Ultra-thin transmissive crystalline silicon high-contrast grating metasurfaces.

Dielectric metasurfaces made from crystalline silicon, titanium dioxide, gallium nitride and silicon nitride have developed rapidly for applications in the visible wavelength regime. High performance metasurfaces typically require the realisation of subwavelength, high aspect ratio nanostructures, the fabrication of which can be challenging. Here, we propose and demonstrate the operation of high performance metasurfaces in ultra-thin (100 nm) crystalline silicon at the wavelength of 532 nm. Using optical beam analysis, we discuss fabrication complexity and show that our approach is more fabrication-tolerant than the nanofin approach, which has so far produced the highest performance metasurfaces, but may be difficult to manufacture, especially when using nanoimprint lithography.

Corrugated organic light-emitting diodes to effectively extract internal modes.

We report a corrugated structure to effectively extract the surface plasmon polaritons (SPP) and waveguiding modes in organic light-emitting diodes (OLEDs). This structure is formed by nano-imprint of blazed gratings. To study the optimum extraction condition in terms of grating pitches, we compare the light extraction efficiency of corrugated OLEDs with three kinds of pitches, showing a 42.00% external quantum efficiency (EQE) enhancement ratio with this internal structure. Due to the transfer of SPP and waveguiding modes into substrate mode, the EQE enhancement ratio can be further pushed to 103.02% by attaching a macrolens. The simulation verifies the experimental results and shows the extraction mechanism of the corrugated structure towards transverse electric (TE) and transverse magnetic (TM) waves. We foresee that this method is able to enhance the optical efficiency of devices for both mass-production OLED lighting and display in a cost-effective way.

Ultrafast switching of optical singularity eigenstates with compact integrable liquid crystal structures.

By using the strong nonlinear effect and ultrafast electronic response of cholesteric liquid crystals (CLC), ultrafast all optical switching between polarization vortex and phase vortex is realized in a system combining CLC and q-plate. The experimental result shows that switching with high modulation depth can be accomplished in less than 1 picosecond. Furthermore, CLC and q-plates will enable compact integrated devices with sub-mm thicknesses.