Comparison of total corneal power measurements obtained with different devices after myopic keratorefractive surgery

AIM:To analyze the differences,agreements,and correlation among total corneal power parameters generated by different instruments after myopic keratorefractive surgery.METHODS:The prospective cross-sectional study included patients who underwent myopic keratorefractive surgery and received measurements of corneal power 3mo after surgery.Automated keratometer was used for the measurement of simulated keratometry(Sim K),sweptsource optical coherence tomography(SS-OCT)based biometer for total keratometry(TK),anterior segment-OCT for real keratometry(RK),and Scheimpflug keratometer for the true net power(TNP),the total corneal refractive power(TCRP)and equivalent K-readings(EKR).The differences among these parameters were analyzed,and the agreements and correlation between Sim K and other total corneal power parameters were investigated.RESULTS:A total of 70 eyes of 70 patients after myopic keratorefractive surgery were included.The evaluated corneal power parameters were as follows:Sim K 38.32±1.93 D,TK 37.54±2.12 D,RK 36.64±2.09 D,TNP 36.56±1.97 D,TCRP 36.70±2.01 D,and EKR 37.55±2.00 D.Pairwise comparison showed that there were significant differences(P<0.001)among all parameters except for between TK and EKR,RK and TNP,RK and TCRP(P=1.000,1.000,1.000,respectively).The limits of agreement between Sim K and TK,RK,TNP,TCPR,and EKR were 1.08,1.08,1.43,1.48,and 1.73 D,respectively.All parameters showed good correlation with Sim K,and the correlation coefficients were 0.995,0.994,0.983,0.982,and 0.975.CONCLUSION:Among the corneal power parameters after myopic keratorefractive surgery,the value of Sim K is the largest,followed by TK and EKR,with TCRP,RK,and TNP being the smallest.The differences among the parameters may be attributable to the different calculation principles.Correct understanding and evaluation of corneal power parameters can provide a theoretical basis for taking advantage of the total corneal power to improve the accuracy of intraocular lens calculation after keratorefractive surgery.

Photocatalytic activity of ferric oxide/titanium dioxide nanocomposite films on stainless steel fabricated by anodization and ion implantation

A simple surface treatment was used to develop photocatalytic activity for stainless steel. AISI 304 stainless steel specimens after anodization were implanted by Ti ions at an extracting voltage of 50 kV with an implantation dose of 3 × 10^15 atoms.cm-2 and then annealed in air at 450℃ for 2 h. The morphology was observed by scanning electron microscopy. The microstructure was characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The photocatalytic degradation of methylene blue solution was carried out under ultraviolet light. The corrosion resistance of the stainless steel was evaluated in NaCl solution （3.5 wt%） by electrochemical polarization curves. It is found that the Ti ions depth profile resembles a Gaussian distribution in the implanted layer. The nanostructured Fe203/TiO2 composite film exhibits a remarkable enhancement in photocatalytic activity referenced to the mechanically polished specimen and anodized specimen. Meanwhile, the annealed Ti-implanted specimen remains good corrosion resistance.

Cavitation research with computational fluid dynamics:From Euler-Euler to Euler-Lagrange approach

Unsteady cavitating flow often contains vapor structures with a wide range of different length scales,from micro-bubbles to large cavities,which issues a big challenge to precisely investigate its evolution mechanism by computational fluid dynamics(CFD)method.The present work reviews the development of simulation methods for cavitation,especially the emerging Euler-Lagrange approach.Additionally,the progress of the numerical investigation of hot and vital issues is discussed,including cavitation inception,cloud cavitation inner structure and its formation mechanism,cavitation erosion,and cavitation noise.It is indicated that the Euler-Lagrange method can determine cavitation inception point better.For cloud cavitation,the Euler-Lagrange method can reveal the source of microbubbles and their distribution law inside the shedding cloud.This method also has advantages and great potential in assessing cloud cavitation-induced erosion and noise.With the ever-growing demands of cavitation simulation accuracy in basic research and engineering applications,how to improve the Euler-Lagrange method’s stability and applicability is still an open problem.To further promote the application of this advanced CFD simulation technology in cavitation research,some key issues are to be solved and feasible suggestions are put forward for further work.

Some notes on numerical simulation of the turbulent cavitating flow with a dynamic cubic nonlinear sub-grid scale model in OpenFOAM

The accuracy of large eddy simulation(LES)is highly dependent on the performance of sub-grid scale(SGS)model.In the present paper,a dynamic cubic nonlinear sub-grid scale model(DCNM)proposed by Huang et al.is implemented for the simulation of unsteady cavitating flow around a 3-D Clark-Y hydrofoil in OpenFOAM.Its performance in predicting the evolution of cloud cavitation is discussed in detail.The simulation with a linear model,the dynamic Smagorinsky model(DSM),is also conducted as a comparison.The results with DCNM show a better agreement with the available experimental observation.The comparison between DCNM and DSM further suggests that the DCNM is able to predict the backscatter more precisely,which is an important feature in LES.The characteristics of DCNM is analyzed to account for its advantages in the prediction of unsteady cloud cavitation as well.The results reveal that it is the nonlinear terms of DCNM that makes DCNM capture sub-grid scale vortices better and more suitable for studying the transient behaviors of cloud cavitation than DSM.

基于暗通道先验的单幅图像快速去雾算法（英文）

在雾气中,可见光的散射降低了图像可见度。目前,去雾仍是图像处理应用的一个挑战。为实现去雾,提出一种基于单个像素的去雾加速算法。不同于基于区块的方法,所提方法分别估计每个区域的变换矩阵和大气光参数,其中加速的关键在于所有参数能在一次遍历中获得。然后,对传输映射进行双边过滤,恢复像素之间的关系。通过线性模糊模型恢复后,对恢复的图像进行调整,以提高对比度、光照强度和饱和度,尤其是补偿由相应波长引起的不同通道的光强误差。实验结果表明,该方法在处理速率方面优于已有的最先进去雾算法。与其他去雾方法比较和引入定量准则(峰信噪比、可检测边际速率、信息熵差)验证该方法有效。

Representation learning via a semi-supervised stacked distance autoencoder for image classification

Image classification is an important application of deep learning. In a typical classification task, the classification accuracy is strongly related to the features that are extracted via deep learning methods. An autoencoder is a special type of neural network, often used for dimensionality reduction and feature extraction. The proposed method is based on the traditional autoencoder, incorporating the "distance" information between samples from different categories. The model is called a semisupervised distance autoencoder. Each layer is first pre-trained in an unsupervised manner. In the subsequent supervised training, the optimized parameters are set as the initial values. To obtain more suitable features, we use a stacked model to replace the basic autoencoder structure with a single hidden layer. A series of experiments are carried out to test the performance of different models on several datasets, including the MNIST dataset, street view house numbers(SVHN) dataset, German traffic sign recognition benchmark(GTSRB), and CIFAR-10 dataset. The proposed semi-supervised distance autoencoder method is compared with the traditional autoencoder, sparse autoencoder, and supervised autoencoder. Experimental results verify the effectiveness of the proposed model.

The calibration model in potassium ion flux non-invasive measurement of plants in vivo in situ

SIET(Self-referencing Ion Electrode Technique)provides a novel electrophysiological tool which can non-invasively measure the dynamic influxes and effluxes of ions caused by the diffusion along the concentration gradients in vivo.However,in this technique ion fluxes are converted to voltage signals using an ion selective microelectrode at a small amplitude of lV,which is easy to be interfered by the ambient noise.Hence,effective solutions to the suppression of noise and calibration of ion flux measurement system are very important for this method.A K^+-selective microelectrode was constructed using liquid ion exchangers(LIX)to investigate ion transport over plant tissue.A standard concentration gradient which simulates plant living cells was produced by an electrode with a certain tip diameter,filled with a solution containing a known K+concentration in 100 mmol/L.An ion diffusion simulation model was established.This model evaluated the performance of ion flux measurement system in accuracy and reliability by comparing the consistency of the measured value and the predicted curve.K^+fluxes were measured within 25 min at each measuring point of distance 10,20,30,40,50,80,and 100 lm from the K+source,respectively.It can be seen that the K^+fluxes changes little,which indicates that ion flux measurement system has a reliable stability.The study provides a theoretical basis for a new non-invasive ion flux measurement method creation and a new sensors design.

An Immersive Virtual Reality System for Rodents in Behavioral and Neural Research

Context cognition involves abstractly deriving meaning from situational information in the world and is an important psychological function of higher cognition. However, due to the complexity of contextual information processing, along with the lack of relevant technical tools, little remains known about the neural mechanisms and behavioral regulation of context cognition. At present, behavioral training with rodents using virtual reality techniques is considered a potential key for uncovering the neurobiological mechanisms of context cognition. Although virtual reality technology has been preliminarily applied in the study of context cognition in recent years, there remains a lack of virtual scenario integration of multi-sensory information, along with a need for convenient experimental design platforms for researchers who have little programming experience. Therefore, in order to solve problems related to the authenticity, immersion, interaction, and flexibility of rodent virtual reality systems, an immersive virtual reality system based on visual programming was constructed in this study. The system had the ability to flexibly modulate rodent interactive 3 D dynamic experimental environments. The system included a central control unit, virtual perception unit, virtual motion unit, virtual vision unit, and video recording unit. The neural circuit mechanisms in various environments could be effectively studied by combining two-photon imaging and other neural activity recording methods. In addition, to verify the proposed system′s performance, licking experiments were conducted with experimental mice. The results demonstrated that the system could provide a new method and tool for analyzing the neural circuits of the higher cognitive functions in rodents.

Numerical simulation of multi-scale cavitating flow with special emphasis on the influence of vortex on micro-bubbles

A multi-scale Euler-Lagrange method is applied in the current paper to investigate the characteristics of turbulent cloud cavitating flow around a Clark-Y hydrofoil,in which macroscopic cavitating structures are simulated by volume of fluid(VOF)approach,while micro-scale bubbles are modelled based on Rayleigh-Plesset equation and bubble motion equation.The numerical results are in reasonable agreement with the available experiments,and the transition between multi-scale structures is captured clearly.The evolution of microscopic bubble behaviors is statistically investigated.During one typical cycle,numbers and Sauter mean radius of the bubbles show a similar variation tendency which both sharply spike to their maxima after the breakup of the sheet cavity,and then decrease continuously to their minima before the next breakup.Discrete bubbles are mainly concentrated at the tail of the attached cavity,in front of the cloud cavity and in the region quite close to the hydrofoil suction side.Furthermore,vortices are extracted to account for the micro-scale hydrodynamics.It is found that intense vortices aggravate turbulence fluctuation,thus spalling cavity to generate massive micro bubbles.Meanwhile,the vortices provide microscopic bubbles low pressure and detain them so that numerous bubbles are able to grow.These effects are remarkable after the breakup of attached sheet cavity,owing to the violent vortices generated.On the contrary,when sheet cavity develops,the flow field becomes comparatively stable since the strong vortices travel downstream.Few micro-scale bubbles are produced,and their volume is generally small.

Development of a portable multi-channel system for plant physiological signal recording

Bioelectrical signals can reflect physiological state of organs or tissues in plants and have a significant potential value in research of plant stress tolerance.In order to study the relationship between environment factors and electrical signals in plant,a portable multichannel physiological signal acquisition system which relevant in plant physiology research was developed.Environment parameters and electrical signals can be measured in different channels by the acquisition system simultaneously and the measurement data will be displayed in an embedded integrated touch screen which is the system processing core.The system was validated to be stable and reliable after the calibration and repeated experiments of recording electrical signals in Helianthus annuus L.