Siamese Transformer-Based Building Change Detection in Remote Sensing Images.

To address the challenges of handling imprecise building boundary information and reducing false-positive outcomes during the process of detecting building changes in remote sensing images, this paper proposes a Siamese transformer architecture based on a difference module. This method introduces a layered transformer to provide global context modeling capability and multiscale features to better process building boundary information, and a difference module is used to better obtain the difference features of a building before and after a change. The difference features before and after the change are then fused, and the fused difference features are used to generate a change map, which reduces the false-positive problem to a certain extent.

Improved SSA-Based GRU Neural Network for BDS-3 Satellite Clock Bias Forecasting.

Satellite clock error is a key factor affecting the positioning accuracy of a global navigation satellite system (GNSS). In this paper, we use a gated recurrent unit (GRU) neural network to construct a satellite clock bias forecasting model for the BDS-3 navigation system. In order to further improve the prediction accuracy and stability of the GRU, this paper proposes a satellite clock bias forecasting model, termed ITSSA-GRU, which combines the improved sparrow search algorithm (SSA) and the GRU, avoiding the problems of GRU's sensitivity to hyperparameters and its tendency to fall into local optimal solutions.

Injectable self-crosslinking hydrogels based on hyaluronic acid as vitreous substitutes.

After vitrectomy, the ideal vitreous substitute should be implanted to maintain the normal function of the eye. However, the existing materials (such as silicone oil, air, perfluorocarbons, etc.) still have some shortcomings and cannot fully meet the clinical needs.

A self-healing and injectable hydrogel based on water-soluble chitosan and hyaluronic acid for vitreous substitute.

Vitreous, an essential dioptric medium for the human eyes, must be filled with artificial materials once damaged. Carboxymethyl chitosan (CMCTS) is one of the most important water-soluble chitosan derivatives with improved biocompatibility and biodegradability. In this study, oxidized hyaluronic acid (OHA) was prepared as crosslinking reagent.

Experimental Study of a Signal Modulation Method to Improve eLORAN Data Channel Communications.

There are mainly two types of data modulation methods used for enhanced LOng-RAnge Navigation (eLORAN) systems: pulse position modulation (PPM) and supernumerary interpulse modulation (SIM). The typical application for PPM is tri-state PPM (3S-PPM), also known as Eurofix. The typical application for SIM is ninth pulse modulation.

Common-View Time Transfer Using Geostationary Satellite.

The National Time Service Center (NTSC), Chinese Academy of Sciences (CAS), Xi'an, China, has developed a method for common-view time transfer using Geostationary Earth Orbit (GEO) satellite (GCV) applicable to the time and frequency transfer at distant stations. This method is independent of Global Navigation Satellite System (GNSS) time and frequency transfer, as well as two-way satellite time and frequency transfer (TWSTFT). A master clock at the time laboratory transmits pseudorandom code signals to a GEO telecommunication satellite, and the time signals are retransmitted by the satellite.

The feasibility study of an in situ marine polysaccharide-based hydrogel as the vitreous substitute.

Although various biopolymers and synthetic compounds have been proposed and tested as the vitreous substitutes, no ideal material has been identified yet. In the present study, we developed an in situ-formed hydrogel by crosslinking hydroxypropyl chitosan with alginate dialdehyde. Physical properties of the hydrogel were studied and the cytotoxicity was evaluated using L929 fibroblasts, rabbit corneal endothelial cells and retinal pigment epithelial cells.

Evaluation of a photocrosslinkable hydroxyethyl chitosan hydrogel as a potential drug release system for glaucoma surgery.

Hydroxyethyl chitosan (HECTS) is a critical derivative of chitosan that has been widely used as biomedical materials due to great water-solubility and excellent biocompatibility. Here, photosensitive hydroxyethyl chitosan was synthesized by introducing azide group on NH2 of HECTS (HECTS-AZ), afterwards FTIR and H NMR spectra were detected to confirm the formation of HECTS-AZ. The solution of HECTS-AZ can achieve a sol-gel transition through UV irradiation for 30 s.

Therapeutic efficiency of tissue-engineered human corneal endothelium transplants on rabbit primary corneal endotheliopathy.

To evaluate the therapeutic efficiency of tissue-engineered human corneal endothelia (TE-HCEs) on rabbit primary corneal endotheliopathy (PCEP), TE-HCEs reconstructed with monoclonal human corneal endothelial cells (mcHCECs) and modified denuded amniotic membranes (mdAMs) were transplanted into PCEP models of New Zealand white rabbits using penetrating keratoplasty. The TE-HCEs were examined using diverse techniques including slit-lamp biomicroscopy observation and pachymeter and tonometer measurements in vivo, and fluorescent microscopy, alizarin red staining, paraffin sectioning, scanning and transmission electron microscopy observations in vitro. The corneas of transplanted eyes maintained transparency for as long as 200 d without obvious edema or immune rejection.

Fabrication and characters of a corneal endothelial cells scaffold based on chitosan.

A novel chitosan-based membrane that made of hydroxyethyl chitosan, gelatin and chondroitin sulfate was used as a carrier of corneal endothelial cells. The characteristics of the blend membrane including transparency, equilibrium water content, ion and glucose permeability were determined. The results showed that the optical transparency of the membrane was as good as the natural human cornea.

An in situ formed biodegradable hydrogel for reconstruction of the corneal endothelium.

Biodegradable hydrogels are important biomaterials for tissue engineering and drug delivery. For the purpose of corneal regenerative medicine, we describe an in situ formed hydrogel based on a water-soluble derivative of chitosan, hydroxypropyl chitosan (HPCTS), and sodium alginate dialdehyde (SAD). Periodate oxidized alginate rapidly cross-links HPCTS due to Schiff's base formation between the available aldehyde and amino groups.

Preparation and properties of a chitosan-based carrier of corneal endothelial cells.

A novel chitosan-based membrane that was made of hydroxypropyl chitosan, gelatin and chondroitin sulfate was used as a carrier of corneal endothelial cells. The characteristics of the blend membrane, such as transparency, equilibrium water content, permeability, mechanical properties, protein absorption ability, hydrophilicity and surface morphology, were determined. To study the effects of the membrane on cell attachment and growth, rabbit corneal endothelial cells were cultured on this artificial membrane.