Extracting intraocular foreign body at or near the ciliary body with scleral indentation in direct visualization

Dear Editor,I＇m Dr. Qing-Huai Liu from Department of Ophthalmology, the First Affiliated Hospital of Nanjing Medical University,Nanjing, China. I write to present four cases diagnosed with the intraocular foreign body （IOFB） at or near the ciliary body and to evaluate the effect of extracting IOFB with scleral indentation in direct visualization.

Direct visualization of structural defects in 2D semiconductors

Direct visualization of the structural defects in two-dimensional(2D)semiconductors at a large scale plays a significant role in understanding their electrical/optical/magnetic properties,but is challenging.Although traditional atomic resolution imaging techniques,such as transmission electron microscopy and scanning tunneling microscopy,can directly image the structural defects,they provide only local-scale information and require complex setups.Here,we develop a simple,non-invasive wet etching method to directly visualize the structural defects in 2D semiconductors at a large scale,including both point defects and grain boundaries.Utilizing this method,we extract successfully the defects density in several different types of monolayer molybdenum disulfide samples,providing key insights into the device functions.Furthermore,the etching method we developed is anisotropic and tunable,opening up opportunities to obtain exotic edge states on demand.

Scalable preparation and direct visualization of cyclic polymers via self-folding cyclization technique

Cyclic polymers exhibit distinct properties compared with their linear counterparts due to the lack of chain ends.However,the scalable synthesis of cyclic polymers remains a major challenge,especially for ring-closure method.Herein,we report a novel strategy for large-scale preparation of cyclic polymers,which relies on the prior self-folding of anthracene-telechelic amphiphilic random copolymers(poly((oligo(ethylene glycol)acrylate)-co-(dodecyl acrylate)),P(OEGA-co-DDA))into single-chain polymeric nanoparticles(SCPNs)in water.Subsequent ultraviolet(UV)-induced cyclization occurs in the hydrophobic nano-domain.The formation of SCPNs leads to a shortened distance between the end groups of the linear precursors and spatially separated cyclization loci,and significantly enhances the efficiency of UV-induced cyclization.This self-folding technique permits access to the synthesis of cyclic polymers not only with high molecular weights(M_(n)>10^(5) g/mol),but also in a decent scale(40 g/L),breaking through the limitations of ring-closure method.Furthermore,the dense pendants of the copolymers can magnify the macromolecules by increasing the mass density along the backbones,thus making the polymers more readily detectable by the microscopy.The transmission electron microscopy(TEM)and atomic force microscopy(AFM)images allow us to observe the topological structures directly and provide crucial evidence to confirm the cyclization.

Preparing cyclic polymers at high concentrations via self-folding cyclization technique by adjusting the contents of hydrophilic units in linear precursors

Cyclic polymers are a class of polymers that feature endless topology,and the synthesis of cyclic polymers has attracted the attention of many researchers.Herein,cyclic polymers were efficiently constructed by self-folding cyclization technique at high concentrations.Linear poly((oligo(ethylene glycol)acrylate)-co-(dodecyl acrylate))(P(OEGA-co-DDA))precursors with different ratios of hydrophilic and hydrophobic moieties were synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization using a bifunctional chain transfer agent with two anthryl end groups.The amphiphilic linear precursors underwent the self-folding process to generate polymeric nanoparticles in water.By irradiating the aqueous solution of the nanoparticles with 365 nm UV light,cyclic polymers were synthesized successfully via coupling of anthryl groups.The effects of the ratios of hydrophilic and hydrophobic moieties in linear P(OEGA-co-DDA)copolymers and polymer concentration on the purity of the obtained cyclic polymers were explored in detail via ^(1)H nuclear magnetic resonance(^(1)H NMR),dynamic light scattering(DLS),UV‒visible(vis)analysis,three-detection size exclusion chromatography(TD-SEC)and transmission electron microscopy(TEM).It was found that by adjusting the content of the hydrophilic segments in linear precursors,single chain polymeric nanoparticles(SCPNs)can be generated at high polymer concentrations.Therefore,cyclic polymers with high purity can be constructed efficiently.This method overcomes the limitation of traditional ring-closure method,which is typically conducted in highly dilute conditions,providing an efficient method for the scalable preparation of cyclic polymers.

Real-time Visual Odometry Estimation Based on Principal Direction Detection on Ceiling Vision

In this paper,we present a novel algorithm for odometry estimation based on ceiling vision.The main contribution of this algorithm is the introduction of principal direction detection that can greatly reduce error accumulation problem in most visual odometry estimation approaches.The principal direction is defned based on the fact that our ceiling is flled with artifcial vertical and horizontal lines which can be used as reference for the current robot s heading direction.The proposed approach can be operated in real-time and it performs well even with camera s disturbance.A moving low-cost RGB-D camera（Kinect）,mounted on a robot,is used to continuously acquire point clouds.Iterative closest point（ICP） is the common way to estimate the current camera position by registering the currently captured point cloud to the previous one.However,its performance sufers from data association problem or it requires pre-alignment information.The performance of the proposed principal direction detection approach does not rely on data association knowledge.Using this method,two point clouds are properly pre-aligned.Hence,we can use ICP to fne-tune the transformation parameters and minimize registration error.Experimental results demonstrate the performance and stability of the proposed system under disturbance in real-time.Several indoor tests are carried out to show that the proposed visual odometry estimation method can help to signifcantly improve the accuracy of simultaneous localization and mapping（SLAM）.