UGLS: an uncertainty guided deep learning strategy for accurate image segmentation.

Accurate image segmentation plays a crucial role in computer vision and medical image analysis. In this study, we developed a novel uncertainty guided deep learning strategy (UGLS) to enhance the performance of an existing neural network (i.e., U-Net) in segmenting multiple objects of interest from images with varying modalities. In the developed UGLS, a boundary uncertainty map was introduced for each object based on its coarse segmentation (obtained by the U-Net) and then combined with input images for the fine segmentation of the objects. We validated the developed method by segmenting optic cup (OC) regions from color fundus images and left and right lung regions from Xray images. Experiments on public fundus and Xray image datasets showed that the developed method achieved a average Dice Score (DS) of 0.8791 and a sensitivity (SEN) of 0.8858 for the OC segmentation, and 0.9605, 0.9607, 0.9621, and 0.9668 for the left and right lung segmentation, respectively. Our method significantly improved the segmentation performance of the U-Net, making it comparable or superior to five sophisticated networks (i.e., AU-Net, BiO-Net, AS-Net, Swin-Unet, and TransUNet).

Semi-supervised image segmentation using a residual-driven mean teacher and an exponential Dice loss.

Semi-supervised segmentation plays an important role in computer vision and medical image analysis and can alleviate the burden of acquiring abundant expert-annotated images. In this paper, we developed a residual-driven semi-supervised segmentation method (termed RDMT) based on the classical mean teacher (MT) framework by introducing a novel model-level residual perturbation and an exponential Dice (eDice) loss. The introduced perturbation was integrated into the exponential moving average (EMA) scheme to enhance the performance of the MT, while the eDice loss was used to improve the detection sensitivity of a given network to object boundaries. We validated the developed method by applying it to segment 3D Left Atrium (LA) and 2D optic cup (OC) from the public LASC and REFUGE datasets based on the V-Net and U-Net, respectively. Extensive experiments demonstrated that the developed method achieved the average Dice score of 0.8776 and 0.7751, when trained on 10% and 20% labeled images, respectively for the LA and OC regions depicted on the LASC and REFUGE datasets. It significantly outperformed the MT and can compete with several existing semi-supervised segmentation methods (i.e., HCMT, UAMT, DTC and SASS).

Demonstration of Ultra-High-Q Silicon Microring Resonators for Nonlinear Integrated Photonics.

A reflowing photoresist and oxidation smoothing process is used to fabricate ultra-high-Q silicon microring resonators based on multimode rib waveguides. Over a wide range of wavelengths near 1550 nm, the average Q-factor of a ring with 1.2-µm-wide waveguides reaches up to 1.17 × 106, with a waveguide loss of approximately 0.28 dB/cm. For a resonator with 1.5-µm-wide waveguides, the average Q-factor reaches 1.20 × 106, and the waveguide loss is 0.27 dB/cm. Moreover, we theoretically and experimentally show that a reduction in the waveguide loss significantly improves the conversion efficiency of four-wave mixing. A high four-wave mixing conversion efficiency of -17.0 dB is achieved at a pump power of 6.50 dBm.

A One-Step Electrochemical Aptasensor Based on Signal Amplification of Metallo Nanoenzyme Particles for Vascular Endothelial Growth Factor.

In this study, a one-step electrochemical aptasensor was developed to detect the biomarker vascular endothelial growth factor (VEGF), an important protein in the pathogenesis of many retinal diseases, including age-related macular degeneration, diabetic retinopathy, retinopathy of prematurity, and retinal vein occlusion. The aptamer has a good affinity and can rapidly identify and capture VEGF based on its unique structure. We designed a VEGF aptasensor based on the aptamer recognition and complex metallo nanoenzyme particles as an electron exchange center and bridge between capture DNA and electrode. The aptamers maintained the hairpin structure to avoid nonspecific surface adsorption and expose the capture sequence outwards when the target was inexistent. Conversely, the aptamers opened the hairpin structure to release space to accomplish binding between VEGF and DNA, resulting in increased impedance. The performance of the electrochemical aptasensor is detected by electrochemical impedance spectroscopy (EIS). The limit of detection by EIS was as low as 8.2 pg ml-1, and the linear range was 10 pg ml-1-1 µg ml-1. The electrochemical aptasensor also showed high specificity and reproducibility.

Integrated photonic devices enabled by silicon traveling wave-like Fabry-Perot resonators.

Integrated photonic devices play a key role in modern optical communications, of which optical resonators are important fundamental structures. This work proposes and experimentally demonstrates compact integrated photonic devices based on a traveling wave-like Fabry-Perot (TW-like FP) resonator(s) coupled with waveguides. Add-drop filters based on a single TW-like FP resonator have been realized with a high drop efficiency and the same output direction for the through and drop ports. Particularly, their transmission response can be either symmetric Lorentzian or asymmetric Fano line shape, through adjusting the shift between the two bus waveguides and the waveguide widths. Fano resonance has been demonstrated in a TW-like FP resonator with a very high extinction ratio and large slope rate. The second-order optical filter exhibits low-loss flat-top passbands with small ripples. Owing to the compact size, easy scalability, and large flexibility, TW-like FP cavity-based devices using Fano and Lorentzian resonances will provide new potential applications in integrated photonics.

Hydrogel eye drops as a non-invasive drug carrier for topical enhanced Adalimumab permeation and highly efficient uveitis treatment.

Uveitis is one of the most popular blind-causing eye diseases worldwide. Adalimumab (ADA) is used for the uveitis treatment through systemic or intravitreal injection at the expense of systemic side effects and increased medical risks. Although eye drops, a non-invasive topical treatment, could be a potential strategy to reduce side effects, it remains challenging to apply due to limited bioavailability mainly linked to poor retention time and permeation capacity for eye biological barriers. Here, we reported hydrogel eye drops composed of low-deacetylated chitosan and ß-glycerophosphate as an ADA carrier and tested its toxicity, tolerability, intraocular permeability, and efficacy of non-invasive treatment for uveitis. It's found the ADA-loaded hydrogel eye drops were more efficient than free ADA both in permeation rate and clinical efficacy for uveitis, Overall, this study provides a friendly non-invasive strategy to improve drug permeation rate and uveitis treatment efficacy, which may be valuable to clinically ophthalmic medication.

Microenvironment-Triggered Degradable Hydrogel for Imaging Diagnosis and Combined Treatment of Intraocular Choroidal Melanoma.

Human choroidal melanoma (HCM) is one of the most common primary intraocular tumors and easily provokes liver metastases owing to the lack of sensitive and noninvasive therapeutic methods. Concerning the imaging diagnostics and therapeutic predicaments for choroidal melanoma, we designed microenvironment-triggered degradable hydrogels (RENP-ICG@PNIPAM:Dox-FA) based on ultrasmall (<5 nm) rare-earth nanoparticles (RENPs) with enhanced NIR-II luminescence. The ultrasmall diameter can significantly enhance the NIR-II luminescence performance of RENPs. RENPs were encapsulated by a dual-response PNIPAM hydrogel, which could release drug by responding to heat energy and glutathione under the tumor microenvironment. The in vitro/in vivo NIR-II imaging detection and antitumor activity were also compared systematically after different treatment conditions on ocular choroidal melanoma-1 cells and tumor-bearing mice, respectively. Besides, the degradability of the hydrogel composites under physiological conditions could be conducive to enhance the photothermal-chemotherapeutic effect and alleviate long-term biological toxicity. Our work on the microenvironment-triggered hydrogels with enhanced NIR imaging and easy metabolism may provide a promising strategy for sensitive and noninvasive imaging and phototherapy in ocular tumors.

The precision and agreement of corneal thickness and keratometry measurements with SS-OCT versus Scheimpflug imaging.

PURPOSE: To assess the repeatability and reproducibility of swept-source optical coherence tomography (SS-OCT) and Scheimpflug system and evaluate the agreement between the two systems in measuring multiple corneal regions in children. METHODS: Pachymetric and keratometric maps for both systems were evaluated. Central, midperipheral and peripheral corneal thickness (CT), keratometry and astigmatism power vectors were recorded. The three outcomes yielded by the same observer were used to assess intraobserver repeatability. The differences in the mean values provided by each observer were used to evaluate interobserver reproducibility. Within-subject standard deviation, test-retest repeatability (TRT) and coefficient of variation (CoV) were used to analyze the intraobserver repeatability and interobserver reproducibility. Paired T-test and Bland-Altman were used to appraise interdevice agreement. RESULTS: Seventy-eight eyes of 78 children were included. The CoV was ≤2.12 and 1.10%, respectively, for repeatability and reproducibility. TRT and CoV were lower for central and paracentral CT measurements than for peripheral measurements. The SS-OCT device generated higher precision when acquiring CT data, whereas Scheimpflug system showed higher reliability when measuring corneal keratometry. Although the CT readings measured using SS-OCT were significantly thinner than Scheimpflug device (P <  0.001), the central and thinnest CT values were still of high agreement. The interdevice agreement of keratometry measurement was high for the central corneal region and moderate for the paracentral and peripheral areas. CONCLUSIONS: The precision of CT measurements by SS-OCT was higher, while the reliability of keratometry measurements by the Scheimpflug system was higher in children. Apart from the measured values in the central corneal region, the thickness and keratometry readings should not be considered interchangeable between the two systems.

Protein Enables Conformation Transition of a Hydrogel Based on Pentapeptide and Boosts Immune Response in Vivo.

We report a supramolecular hydrogel based on dihistidine containing pentapeptides serving as a novel vaccine delivery system. Protein encapsulated into the hydrogel not only enhances the mechanical property up to 15-fold but also changes the conformation of the resulting nanostructure from a ß-sheet to an α-helix. The resulting hybrid hydrogel enhances antigen uptake and moderately promotes dendritic cell (DC) maturation in vitro. More importantly, the pentapeptide hydrogel promotes antigen-specific antibody production in vivo and splenocyte proliferation ex vivo.

Highly sensitive and selective electrochemical detection of Hg(2+) through surface-initiated enzymatic polymerization.

A Hg(2+) electrochemical biosensor is developed by integrating thymine-Hg(2+)-thymine (T-Hg(2+)-T) base pairs for the high selectivity with surface-initiated enzymatic polymerization (SIEP) for signal amplification. The fabrication begins with the covalent conjugation of capture DNA probe labeled with thiol at its 3'terminal onto the gold electrode. The presence of Hg(2+) leads to DNA hybridization, in which complementary DNA was captured onto the biosensor surface, which subsequently catalyzed the addition of deoxynucleotides (dNTP) containing biotinlated 2'-deoxyadenosine 5'-triphosphate (biotin-dATP) by terminal deoxynucleotidyl transferase (TdT). The binding between biotin and strepavidin leads to the attachment of a large number of strepavidin functionalized silver nanoparticles (strepavidin-AgNPs), which could generate electrochemical stripping signal of silver to monitor the concentration of Hg(2+) in KCl solution. Through utilizing the T-Hg(2+)-T selectivity and SIEP amplification, this assay method can detect aqueous Hg(2+) with a wide linear range from 0.05 nM to 100 nM and a detection limit of 0.024 nM. The application of this sensor in the analysis of drinking water demonstrates that the proposed method works well for real samples.