A biodegradable and flexible neural interface for transdermal optoelectronic modulation and regeneration of peripheral nerves.

Optoelectronic neural interfaces can leverage the photovoltaic effect to convert light into electrical current, inducing charge redistribution and enabling nerve stimulation. This method offers a non-genetic and remote approach for neuromodulation. Developing biodegradable and efficient optoelectronic neural interfaces is important for achieving transdermal stimulation while minimizing infection risks associated with device retrieval, thereby maximizing therapeutic outcomes. We propose a biodegradable, flexible, and miniaturized silicon-based neural interface capable of transdermal optoelectronic stimulation for neural modulation and nerve regeneration. Enhancing the device interface with thin-film molybdenum significantly improves the efficacy of neural stimulation. Our study demonstrates successful activation of the sciatic nerve in rodents and the facial nerve in rabbits. Moreover, transdermal optoelectronic stimulation accelerates the functional recovery of injured facial nerves.

Clinical characteristics and aetiology of uveitis in a viral haemorrhagic fever zone.

BACKGROUND/OBJECTIVES: Studies on uveitis in Sierra Leone were conducted prior to the Ebola Virus Disease epidemic of 2013-16, which was associated with uveitis in 20% of survivors. They did not include imaging or investigation of tuberculosis and used laboratory services outside the country. We performed a cross-sectional study on patients presenting with uveitis to establish their clinical characteristics and identify the impact of in-country laboratory diagnoses. METHODS: We invited uveitis cases presenting to Eye Clinics in Sierra Leone from March to September 2022 to participate in the study. They underwent a diagnostic work-up, including fundus and ocular coherence tomography imaging. Active uveitis cases underwent further investigations including serology and immunological tests for syphilis, tuberculosis, herpetic viruses and HIV and chest radiographs. RESULTS: We recruited 128 patients. The median age was 34 (IQR 19) years and there was an equal gender split. Panuveitis was the predominant anatomical uveitis type (n = 51, 40%), followed by posterior uveitis (n = 36, 28%). Bilateral disease affected 40 patients (31%). Active uveitis was identified in 75 (59%) cases. ICD 11 definition of blindness with VA < 3/60 occurred in 55 (33%) uveitis eyes. Aetiology of uveitis from clinical and laboratory assessment demonstrated that most cases were of undifferentiated aetiology (n = 66, 52%), followed by toxoplasmosis (n = 46, 36%). Trauma contributed to eight (6%) cases, syphilis to 5 (4%) cases and Ebola to 2 (2%). CONCLUSIONS: Uveitis was associated with high levels of visual impairment. Posterior and panuveitis contributed to the highest proportion of uveitis cases. Laboratory studies helped differentiate syphilis as a significant aetiology of uveitis.

Fabrication and properties of hydroxyapatite/chitosan composite scaffolds loaded with periostin for bone regeneration.

This paper reports a facile fabrication method of hydroxyapatite/chitosan (HAp/CS) composite scaffold with 3D porous structure without using any chemical cross-linkers. The HAp particles had an urchin-like hollow microstructure and high surface area, which was uniformly dispersed into the pore walls of the HAp/CS scaffold. The addition of HAp can efficiently enhance the mechanical properties and bioactivity of the HAp/CS scaffold. Moreover, periostin was successfully loaded onto the HAp/CS scaffold. When applied to the repair of bone defect in a rat mandibular model, the HAp/CS scaffold loaded with periostin can enhance osteointegration and accelerate bone regeneration. Our research combines periostin with the HAp/CS composite material, which provides a novel strategy to improve bone regeneration and has great application prospect in bone repair fields.

A Bioresorbable and Conductive Scaffold Integrating Silicon Membranes for Peripheral Nerve Regeneration.

Peripheral nerve injury represents one of the most common types of traumatic damage, severely impairing motor and sensory functions, and posttraumatic nerve regeneration remains a major challenge. Electrical cues are critical bioactive factors that promote nerve regrowth, and bioartificial scaffolds incorporating conductive materials to enhance the endogenous electrical field have been demonstrated to be effective. The utilization of fully biodegradable scaffolds can eliminate material residues, and circumvent the need for secondary retrieval procedures. Here, a fully bioresorbable and conductive nerve scaffold integrating N-type silicon (Si) membranes is proposed, which can deliver both structural guidance and electrical cues for the repair of nerve defects. The entire scaffold is fully biodegradable, and the introduction of N-type Si can significantly promote the proliferation and production of neurotrophic factors of Schwann cells and enhance the calcium activity of dorsal root ganglion (DRG) neurons. The conductive scaffolds enable accelerated nerve regeneration and motor functional recovery in rodents with sciatic nerve transection injuries. This work sheds light on the advancement of bioresorbable and electrically active materials to achieve desirable neural interfaces and improved therapeutic outcomes, offering essential strategies for regenerative medicine.

Clinical Characteristics and Aetiology of Uveitis in a Viral Haemorrhagic Fever Zone.

Background/Objectives: Studies on uveitis in Sierra Leone were conducted prior to the Ebola Virus Disease epidemic of 2013-16, which was associated with uveitis in 20% of survivors. They did not include imaging or investigation of tuberculosis and used laboratory services outside the country. We performed a cross-sectional study on patients presenting with uveitis to establish their clinical characteristics and identify the impact of in-country laboratory diagnoses. Methods: We invited uveitis cases presenting to Eye Clinics in Sierra Leone from March to September 2022 to participate in the study. They underwent a diagnostic work-up, including fundus and ocular coherence tomography imaging. Active uveitis cases underwent further investigations including serology and immunological tests for syphilis, tuberculosis and herpetic viruses and HIV, and chest radiographs. Results: We recruited 128 patients. The mean age was 36 ± 14 years and there was an equal gender split. Panuveitis was the predominant anatomical uveitis type (n=51, 40%), followed by posterior uveitis (n=36, 28%). Bilateral disease affected 40 patients (31%). Active uveitis was identified in 75 (59%) cases. ICD 11 definition of blindness with VA<3/60 occurred in 55 (33%) uveitis eyes. Aetiology of uveitis from clinical and laboratory assessment demonstrated that most cases were of undifferentiated aetiology (n=66, 52%), followed by toxoplasmosis (n=46, 36%). Trauma contributed to eight (6%) cases, syphilis to 5 (4%) cases and Ebola to 2 (2%). Conclusions: Uveitis was associated with high levels of visual impairment. Posterior and panuveitis contributed to the highest proportion of uveitis cases. Laboratory studies helped differentiate syphilis as a significant aetiology of uveitis.

A 3D biomimetic optoelectronic scaffold repairs cranial defects.

Bone fractures and defects pose serious health-related issues on patients. For clinical therapeutics, synthetic scaffolds have been actively explored to promote critical-sized bone regeneration, and electrical stimulations are recognized as an effective auxiliary to facilitate the process. Here, we develop a three-dimensional (3D) biomimetic scaffold integrated with thin-film silicon (Si)-based microstructures. This Si-based hybrid scaffold not only provides a 3D hierarchical structure for guiding cell growth but also regulates cell behaviors via photo-induced electrical signals. Remotely controlled by infrared illumination, these Si structures electrically modulate membrane potentials and intracellular calcium dynamics of stem cells and potentiate cell proliferation and differentiation. In a rodent model, the Si-integrated scaffold demonstrates improved osteogenesis under optical stimulations. Such a wirelessly powered optoelectronic scaffold eliminates tethered electrical implants and fully degrades in a biological environment. The Si-based 3D scaffold combines topographical and optoelectronic stimuli for effective biological modulations, offering broad potential for biomedicine.

Bioresorbable thin-film silicon diodes for the optoelectronic excitation and inhibition of neural activities.

Neural activities can be modulated by leveraging light-responsive nanomaterials as interfaces for exerting photothermal, photoelectrochemical or photocapacitive effects on neurons or neural tissues. Here we show that bioresorbable thin-film monocrystalline silicon pn diodes can be used to optoelectronically excite or inhibit neural activities by establishing polarity-dependent positive or negative photovoltages at the semiconductor/solution interface. Under laser illumination, the silicon-diode optoelectronic interfaces allowed for the deterministic depolarization or hyperpolarization of cultured neurons as well as the upregulated or downregulated intracellular calcium dynamics. The optoelectronic interfaces can also be mounted on nerve tissue to activate or silence neural activities in peripheral and central nervous tissues, as we show in mice with exposed sciatic nerves and somatosensory cortices. Bioresorbable silicon-based optoelectronic thin films that selectively excite or inhibit neural tissue may find advantageous biomedical applicability.

Heteroepitaxy of Large-Area, Monocrystalline Lead Halide Perovskite Films on Gallium Arsenide.

Lead halide perovskite materials have been emerging as promising candidates for high-performance optoelectronic devices. Significant efforts have sought to realize monocrystalline perovskite films on a large scale. Here, we epitaxially grow monocrystalline methylammonium lead tribromide (MAPbBr3) films on lattice-matched gallium arsenide (GaAs) substrates on a centimeter scale. In particular, a solution-processed lead(II) sulfide (PbS) layer provides a lattice-matched and chemical protective interface for the solid-gas reaction to form MAPbBr3 films on GaAs. Structure characterizations identify the crystal orientations in the trilayer MAPbBr3/PbS/GaAs epistructure and confirm the monocrystalline nature of MAPbBr3 on PbS/GaAs. The dynamic evolution of surface morphologies during the growth indicates a two-step epitaxial process. These fundamental understandings and practical growth techniques offer a viable guideline to approach high-quality perovskite films for previously inaccessible applications.

Real-time dense-view imaging for three-dimensional light-field display based on image color calibration and self-supervised view synthesis.

Three-Dimensional (3D) light-field display has achieved promising improvement in recent years. However, since the dense-view images cannot be collected fast in real-world 3D scenes, the real-time 3D light-field display is still challenging to achieve in real scenes, especially at the high-resolution 3D display. Here, a real-time 3D light-field display method with dense-view is proposed based on image color correction and self-supervised optical flow estimation, and a high-quality and high frame rate of 3D light-field display can be realized simultaneously. A sparse camera array is firstly used to capture sparse-view images in the proposed method. To eliminate the color deviation of the sparse views, the imaging process of the camera is analyzed, and a practical multi-layer perception (MLP) network is proposed to perform color calibration. Given sparse views with consistent color, the optical flow can be estimated by a lightweight convolutional neural network (CNN) at high speed, which uses the input image pairs to learn the optical flow in a self-supervised manner. With inverse warp operation, dense-view images can be synthesized in the end. Quantitative and qualitative experiments are performed to evaluate the feasibility of the proposed method. Experimental results show that over 60 dense-view images at a resolution of 1024 × 512 can be generated with 11 input views at a frame rate over 20 fps, which is 4× faster than previous optical flow estimation methods PWC-Net and LiteFlowNet3. Finally, large viewing angles and high-quality 3D light-field display at 3840 × 2160 resolution can be achieved in real-time.

The Spatiotemporal Evolution and Influencing Factors of the Chinese Cities' Ecological Welfare Performance.

In the "full world" where natural capital is scarce, within the limits of the ecological environment, the improvement of welfare is a fundamental requirement for sustainable development. The ecological wellbeing performance (EWP) of 284 cities in China from 2007 to 2020 was measured by the superefficient SBM-DEA model, considering undesirable output, and analyzing the evolutionary trends of overall comprehensive technical efficiency, pure technical efficiency, and scale efficiency. The Theil index was used to explore the source and distribution of the Chinese cities' EWP differences. Exploratory spatial data analysis (ESDA) and the spatial Durbin model (SDM) were applied to analyze the spatial distribution characteristics and driving factors of cities' EWP. The results showed the following: (1) Regarding spatial and temporal distribution, the EWP of Chinese cities showed a fluctuating upward trend, in which pure technical efficiency > scale efficiency. (2) Considering regional differences, the differences in cities' EWP were mainly intraregional rather than interregional. The contribution rates of distinct regions to the differences in EWP varied, i.e., western region > eastern region > central region > northeastern region. (3) In terms of spatial correlation, China's EWP showed positive spatial correlation, i.e., high-high agglomeration and low-low agglomeration. (4) Concerning influencing factors, the level of financial development, the structure of secondary industries, the level of opening-up, and the degree of urbanization significantly improved EWP. Decentralization of fiscal revenue significantly inhibited improvement of EWP. Decentralization of fiscal expenditure and technological progress had no significant impact on the EWP. In the future, to improve cities' EWP, China should focus on reducing differences in intraregional EWP, overcoming administrative regional limitations, encouraging regions with similar locations to formulate coordinated development plans, promoting economic growth, reducing levels of environmental pollution, and paying attention to the improvement of social welfare.

Self-supervised stereo depth estimation based on bi-directional pixel-movement learning.

Stereo depth estimation is an efficient method to perceive three-dimensional structures in real scenes. In this paper, we propose a novel self-supervised method, to the best of our knowledge, to extract depth information by learning bi-directional pixel movement with convolutional neural networks (CNNs). Given left and right views, we use CNNs to learn the task of middle-view synthesis for perceiving bi-directional pixel movement from left-right views to the middle view. The information of pixel movement will be stored in the features after CNNs are trained. Then we use several convolutional layers to extract the information of pixel movement for estimating a depth map of the given scene. Experiments show that our proposed method can significantly provide a high-quality depth map using only a color image as a supervisory signal.

Degradation Study of Thin-Film Silicon Structures in a Cell Culture Medium.

Thin-film silicon (Si)-based transient electronics represents an emerging technology that enables spontaneous dissolution, absorption and, finally, physical disappearance in a controlled manner under physiological conditions, and has attracted increasing attention in pertinent clinical applications such as biomedical implants for on-body sensing, disease diagnostics, and therapeutics. The degradation behavior of thin-film Si materials and devices is critically dependent on the device structure as well as the environment. In this work, we experimentally investigated the dissolution of planar Si thin films and micropatterned Si pillar arrays in a cell culture medium, and systematically analyzed the evolution of their topographical, physical, and chemical properties during the hydrolysis. We discovered that the cell culture medium significantly accelerates the degradation process, and Si pillar arrays present more prominent degradation effects by creating rougher surfaces, complicating surface states, and decreasing the electrochemical impedance. Additionally, the dissolution process leads to greatly reduced mechanical strength. Finally, in vitro cell culture studies demonstrate desirable biocompatibility of corroded Si pillars. The results provide a guideline for the use of thin-film Si materials and devices as transient implants in biomedicine.

Colocalized, bidirectional optogenetic modulations in freely behaving mice with a wireless dual-color optoelectronic probe.

Optogenetic methods provide efficient cell-specific modulations, and the ability of simultaneous neural activation and inhibition in the same brain region of freely moving animals is highly desirable. Here we report bidirectional neuronal activity manipulation accomplished by a wireless, dual-color optogenetic probe in synergy with the co-expression of two spectrally distinct opsins (ChrimsonR and stGtACR2) in a rodent model. The flexible probe comprises vertically assembled, thin-film microscale light-emitting diodes with a lateral dimension of 125 × 180 µm2, showing colocalized red and blue emissions and enabling chronic in vivo operations with desirable biocompatibilities. Red or blue irradiations deterministically evoke or silence neurons co-expressing the two opsins. The probe interferes with dopaminergic neurons in the ventral tegmental area of mice, increasing or decreasing dopamine levels. Such bidirectional regulations further generate rewarding and aversive behaviors and interrogate social interactions among multiple mice. These technologies create numerous opportunities and implications for brain research.

Feasibility of laparoscopic indirect inguinal hernia repair with lateral umbilical fold covering internal inguinal ring combined with patch repair.

Introduction: For an indirect inguinal hernia (IIH), it is a challenge to repair the internal inguinal ring (IIR) with self-tissue reconstruction in laparoscopic repair. Aim: To evaluate the efficacy and safety of covering the IIR with the lateral umbilical fold (LUF) combined with patch repair in laparoscopic indirect inguinal hernia repair. Material and methods: Patients with IIH treated by trans-abdominal preperitoneal (TAPP) hernia repair at the Department of General Surgery, Shanghai Public Health Clinical Centre between September 2019 and March 2021 were retrospectively analyzed. In group I (n = 57) the LUF was overturned and sutured to cover the IIR under a laparoscope and subsequently repaired with a patch. In group II (n = 62), the IIR was not covered by the LUF but only repaired with a self-gripping mesh. Results: We noted a longer suture time in group I than in group II. Although the LUF was covered after suturing, no significant difference in postoperative pain was observed between the two groups. However, significant differences in surgery time and hospitalization cost (p < 0.05) were found. One case of recurrence was observed in group II. Conclusions: The LUF can be used in IIH to cover the IIR and is a feasible approach. The LUF covering the IIR has no significant difference in pain.

Real-time optical reconstruction for a three-dimensional light-field display based on path-tracing and CNN super-resolution.

Three-Dimensional (3D) light-field display plays a vital role in realizing 3D display. However, the real-time high quality 3D light-field display is difficult, because super high-resolution 3D light field images are hard to be achieved in real-time. Although extensive research has been carried out on fast 3D light-field image generation, no single study exists to satisfy real-time 3D image generation and display with super high-resolution such as 7680×4320. To fulfill real-time 3D light-field display with super high-resolution, a two-stage 3D image generation method based on path tracing and image super-resolution (SR) is proposed, which takes less time to render 3D images than previous methods. In the first stage, path tracing is used to generate low-resolution 3D images with sparse views based on Monte-Carlo integration. In the second stage, a lite SR algorithm based on a generative adversarial network (GAN) is presented to up-sample the low-resolution 3D images to high-resolution 3D images of dense views with photo-realistic image quality. To implement the second stage efficiently and effectively, the elemental images (EIs) are super-resolved individually for better image quality and geometry accuracy, and a foreground selection scheme based on ray casting is developed to improve the rendering performance. Finally, the output EIs from CNN are used to recompose the high-resolution 3D images. Experimental results demonstrate that real-time 3D light-field display over 30fps at 8K resolution can be realized, while the structural similarity (SSIM) can be over 0.90. It is hoped that the proposed method will contribute to the field of real-time 3D light-field display.

Virtual view synthesis for 3D light-field display based on scene tower blending.

Three-dimensional (3D) light-field display has achieved a great improvement. However, the collection of dense viewpoints in the real 3D scene is still a bottleneck. Virtual views can be generated by unsupervised networks, but the quality of different views is inconsistent because networks are separately trained on each posed view. Here, a virtual view synthesis method for the 3D light-field display based on scene tower blending is presented, which can synthesize high quality virtual views with correct occlusions by blending all tower results, and dense viewpoints on 3D light-field display can be provided with smooth motion parallax. Posed views are combinatorially input into diverse unsupervised CNNs to predict respective input-view towers, and towers of the same viewpoint are fused together. All posed-view towers are blended as a scene color tower and a scene selection tower, so that 3D scene distributions at different depth planes can be accurately estimated. Blended scene towers are soft-projected to synthesize virtual views with correct occlusions. A denoising network is used to improve the image quality of final synthetic views. Experimental results demonstrate the validity of the proposed method, which shows outstanding performances under various disparities. PSNR of the virtual views are about 30 dB and SSIM is above 0.91. We believe that our view synthesis method will be helpful for future applications of the 3D light-field display.

Modulation of charge transport through single-molecule bilactam junctions by tuning hydrogen bonds.

Bilactam derivatives with different side groups were synthesized and the twisting angle tuning effect induced by the intramolecular hydrogen bond on the charge transport through their single-molecule junctions was investigated. Molecules with strong intramolecular hydrogen bonds exhibited twice higher conductance because of the reduced dihedral twisting, which was reversible with the addition of hydrogen bond destroying solvent. Our findings reveal that the presence of intramolecular hydrogen bonds promotes the planarization of the molecular structure without additional transmission channels, offering a new strategy for controlling molecular switches via tuning the molecular twisting.

The Impact of IOL Abbe Number on Polychromatic Image Quality of Pseudophakic Eyes.

PURPOSE: The human eye exhibits large amounts (2.5 diopters) of longitudinal chromatic aberration (LCA). Its impact on polychromatic image quality, however, has been shown experimentally and by computer modeling to be small or absent. We hypothesized that modest changes in pseudophakic LCA created by higher and lower Abbe number materials will have little or no impact on polychromatic image quality in pseudophakic eyes. MATERIALS AND METHODS: Using published chromatic and monochromatic aberration data from pseudophakic eyes and higher and lower Abbe number materials (37 and 55), we computed monochromatic point spread functions for 21 wavelengths across the visible spectrum. After weighting by either the RGB spectra of a liquid crystal display or by a flat white spectrum, they were weighted by the human spectral sensitivity function (Vλ) before being added to generate polychromatic PSFs. RESULTS: In the absence of monochromatic aberrations, the reduced LCA due to higher Abbe number intraocular lens (IOL) materials resulted in a reduction of 0.08 diopters in the mean defocus generated by LCA. At the retinal plane, the higher Abbe number pseudophakic model produced improvements in polychromatic modulation transfer functions (MTFs) similar to those generated by a 0.05 diopter reduction in spherical defocus. When monochromatic aberrations were added to make the model more representative of actual pseudophakic eyes, the differences in image quality became sub-threshold for human vision or disappeared completely. CONCLUSION: The anticipated gains in polychromatic image quality from employing higher Abbe number IOL materials with reduced LCA do not materialize in plausible aberrated models of pseudophakic eyes.

Investigation on Microstructures and Mechanical Properties of the Hypoeutectic Al-10Si-0.8Fe-XEr Alloy.

In this paper, the effect of Er addition (0.2, 0.5, 0.65, 0.8, 1.0, and 1.5 wt. %) on the microstructure evolution and tensile properties of as-cast hypereutectic Al-10Si-0.8Fe alloy was investigated. The phases and their morphologies in these alloys were identified by XRD and SEM equipped with EDX with the help of metallographic analysis techniques; the length of the secondary phase (LSP) and secondary dendrite arm spacing (SDAS) of α-Al grain were quantified. The results indicated that the second phases (primary Si, eutectic Si, and iron-rich phases) and α-Al grain were significantly refined when the addition of Er increased from 0 to 0.8 wt. %. The mean LSP and SADS values were decreased to a minimum value when the Er addition reached 0.8 wt. %. However, the second phases and α-Al grain became coarser when the level of Er increased more than 0.8 wt. %. The analysis of XRD shows that Er mainly exists in the form of Er2Si compound. The microstructure modification also has a significant effect on the mechanical properties of the alloy. The yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) increase from 52.86 MPa, 163.84 MPa, and 3.45% to 71.01 MPa, 163.84 MPa, and 5.65%, respectively. From the fracture surface, the promotions of mechanical properties are due to the dispersion and pinning reinforcement caused by the Er2Si phase.

Enhanced Emission of Deep Ultraviolet Light-Emitting Diodes through Using Work Function Tunable Cu Nanowires as the Top Transparent Electrode.

Deep ultraviolet light-emitting diodes (DUV LEDs) (<280 nm) have been important light sources for broad applications in, e.g., sterilization, purification, and high-density storage. However, the lack of excellent transparent electrodes in the DUV region remains a challenging issue. Here, we demonstrate an architectural engineering scheme to flexibly tune the work function of Cu@shell nanowires (NWs) as top transparent electrodes in DUV LEDs. By fast encapsulation of shell metals on Cu NWs and a shift of electron binding energy, the electronic work function could be widely tailored down to 4.37 eV and up to 5.73 eV. It is revealed that the high work function of Cu@Ni and Cu@Pt NWs could overcome the interfacial barrier to p-AlGaN and achieve direct ohmic contact with high transparency (91%) in 200-400 nm. Completely transparent DUV LED chips are fabricated and successfully lighted with sharp top emission (wall-plug efficiency reaches 3%) under a turn-on voltage of 6.4 V. This architectural strategy is of importance in providing highly transparent ohmic electrodes for optoelectronic devices in broad wavelength regions.