SERS detection of surface-adsorbent toxic substances of microplastics based on gold nanoparticles and surface acoustic waves.

Microplastics adsorb toxic substances and act as a transport medium. When microplastics adsorbed with toxic substances accumulate in the body, the microplastics and the adsorbed toxic substances can cause serious diseases, such as cancer. This work aimed to develop a surface-enhanced Raman spectroscopy (SERS) detection method for surface-adsorbent toxic substances by forming gold nanogaps on microplastics using surface acoustic waves (SAWs). Polystyrene microparticles (PSMPs; 1 µm) and polycyclic aromatic hydrocarbons (PAHs), including pyrene, anthracene, and fluorene, were selected as microplastics and toxic substances, respectively. Gold nanoparticles (AuNPs; 50 nm) were used as a SERS agent. The Raman characteristic peaks of the PAHs adsorbed on the surface of PSMPs were detected, and the SERS intensity and logarithm of the concentrations of pyrene, anthracene, and fluorene showed a linear relationship (R2 = 0.98), and the limits of detection were 95, 168, and 195 nM, respectively. Each PAH was detected on the surface of PSMPs, which were adsorbed with toxic substances in a mixture of three PAHs, indicating that the technique can be used to elucidate mixtures of toxic substances. The proposed SERS detection method based on SAWs could sense toxic substances that were surface-adsorbed on microplastics and can be utilized to monitor or track pollutants in aquatic environments.

Long-term changes in the choroidal thickness in patients with unilateral central retinal vein occlusion.

The purpose of this study was to investigate the long-term changes in the choroidal thickness in central retinal vein occlusion (CRVO) following anti-vascular endothelial growth factor (VEGF) treatment. This retrospective study included 41 eyes from 41 patients with treatment-naïve unilateral CRVO. We compared the best-corrected visual acuity (BCVA), subfoveal choroidal thickness (SFCT), and central macular thickness (CMT) of CRVO eyes with those of fellow eyes at baseline, 12 months, and 24 months. Baseline SFCT was significantly higher in CRVO eyes than in fellow eyes (p < 0.001); however, there was no significant difference in the SFCT between CRVO eyes and fellow eyes at 12 months and 24 months. When compared with baseline SFCT, SFCT significantly decreased at 12 months and 24 months in CRVO eyes (all p < 0.001). In patients with unilateral CRVO, SFCT in the CRVO eye was significantly thicker than in the fellow eye at baseline, and after 12 months and 24 months, there was no difference from the fellow eye.

Coffee consumption and diabetic retinopathy in adults with diabetes mellitus.

We aimed to evaluate the association between the prevalence of diabetic retinopathy (DR) and coffee consumption in a Korean population. This cross-sectional study was based on data from the 2008-2011 Korean National Health and Nutrition Survey. Among 37,753 survey participants, the data of 1350 subjects with type 2 diabetes who underwent DR examination were analyzed. DR was graded using the modified Airlie House classification system. Coffee consumption data were obtained through food frequency questionnaires and categorized into four groups: almost none, < 1 cup/day, 1 cup/day, and ≥ 2 cups/day. The relationship between DR and coffee consumption was evaluated using multivariable logistic regression models adjusted for age, sex, education, occupation, income, smoking, alcohol intake, body mass index, physical activity, hypertension, dyslipidemia, diabetes duration, and glycated hemoglobin. The prevalence of DR was 20.0%. Non-proliferative DR was observed in 87.8% of all DR patients, and proliferative DR in 12.2%. The prevalence of DR and vision-threatening DR showed a significantly decreasing tendency according to daily coffee consumption (P for trend 0.025 and 0.005, respectively) after adjustment for possible confounders. This tendency was more prominent in those aged < 65 years (P for trend 0.005 and 0.003, respectively). Our findings suggest coffee consumption might be associated with DR reduction especially in Koreans with diabetes mellitus aged < 65 years.

Classifying neovascular age-related macular degeneration with a deep convolutional neural network based on optical coherence tomography images.

Neovascular age-related macular degeneration (nAMD) is among the main causes of visual impairment worldwide. We built a deep learning model to distinguish the subtypes of nAMD using spectral domain optical coherence tomography (SD-OCT) images. Data from SD-OCT images of nAMD (polypoidal choroidal vasculopathy, retinal angiomatous proliferation, and typical nAMD) and normal healthy patients were analyzed using a convolutional neural network (CNN). The model was trained and validated based on 4749 SD-OCT images from 347 patients and 50 healthy controls. To adopt an accurate and robust image classification architecture, we evaluated three well-known CNN structures (VGG-16, VGG-19, and ResNet) and two customized classification layers (fully connected layer with dropout vs. global average pooling). Following the test set performance, the model with the highest classification accuracy was used. Transfer learning and data augmentation were applied to improve the robustness and accuracy of the model. Our proposed model showed an accuracy of 87.4% on the test data (920 images), scoring higher than ten ophthalmologists, for the same data. Additionally, the part that our model judged to be important in classification was confirmed through Grad-CAM images, and consequently, it has a similar judgment criteria to that of ophthalmologists. Thus, we believe that our model can be used as an auxiliary tool in clinical practice.

Distinguishing retinal angiomatous proliferation from polypoidal choroidal vasculopathy with a deep neural network based on optical coherence tomography.

This cross-sectional study aimed to build a deep learning model for detecting neovascular age-related macular degeneration (AMD) and to distinguish retinal angiomatous proliferation (RAP) from polypoidal choroidal vasculopathy (PCV) using a convolutional neural network (CNN). Patients from a single tertiary center were enrolled from January 2014 to January 2020. Spectral-domain optical coherence tomography (SD-OCT) images of patients with RAP or PCV and a control group were analyzed with a deep CNN. Sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve (AUROC) were used to evaluate the model's ability to distinguish RAP from PCV. The performances of the new model, the VGG-16, Resnet-50, Inception, and eight ophthalmologists were compared. A total of 3951 SD-OCT images from 314 participants (229 AMD, 85 normal controls) were analyzed. In distinguishing the PCV and RAP cases, the proposed model showed an accuracy, sensitivity, and specificity of 89.1%, 89.4%, and 88.8%, respectively, with an AUROC of 95.3% (95% CI 0.727-0.852). The proposed model showed better diagnostic performance than VGG-16, Resnet-50, and Inception-V3 and comparable performance with the eight ophthalmologists. The novel model performed well when distinguishing between PCV and RAP. Thus, automated deep learning systems may support ophthalmologists in distinguishing RAP from PCV.

Comparison of Floaters after Cataract Surgery with Different Viscoelastics.

Purpose: To investigate whether there is a difference between symptoms of floaters according to the type of ophthalmic viscosurgical devices(OVDs) used during phacoemulsification. Methods: A total of 112 eyes had undergone standard phacosurgery with the dispersive OVDs(Group1). Group2 comprised 117 eyes that underwent phacosurgery with the dispersive OVDs, but between continuous curvilinear capsulorhexis and hydrodissection, some OVDs had been removed. Group3 included 120 eyes that had undergone phacosurgery with the cohesive OVDs. Results: 14 eyes (12.5%) of Group1 had new-onset floater after surgery whereas 6 eyes (5.13%) in Group2, and 7 eyes (5.83%) in Group3 at the day after and a week after surgery. This was significantly higher in Group1 than Group2 and Group3, respectively (p=0.047,0.049). Conclusion: Cataract surgery with dispersive OVD can predispose the eye to an increased floater symptom. Therefore, surgeons should consider release some OVDs during hydrodissection with dispersive viscoelastics and keep trying to avoid IOP surge during surgery.

High-Performance Field Emission from a Carbonized Cork.

To broaden the range of application of electron beams, low-power field emitters are needed that are miniature and light. Here, we introduce carbonized cork as a material for field emitters. The light natural cork becomes a graphitic honeycomb upon carbonization, with the honeycomb cell walls 100-200 nm thick and the aspect ratio larger than 100, providing an ideal structure for the field electron emission. Compared to nanocarbon field emitters, the cork emitter produces a high current density and long-term stability with a low turn-on field. The nature of the cork material makes it quite simple to fabricate the emitter. Furthermore, any desired shape of the emitter tailored for the final application can easily be prepared for point, line, or planar emission.

High-speed time-resolved laser-scanning microscopy using the line-to-pixel referencing method.

Fluorescence lifetime imaging microscopy (FLIM) is a powerful technique to visualize photophysical characteristics of biological targets. However, conventional FLIM methods have some limitations that restrict obtaining high-precision images in real time. Here, we propose a high-speed time-resolved laser-scanning microscopy by incorporating a novel line-to-pixel referencing method into the previously suggested analog mean-delay (AMD) method. The AMD method dramatically enhances the photon accumulation speed for achieving the certain precision compared to the time-correlated single-photon counting (TCSPC) method while maintaining high photon efficiency. However, its imaging pixel rate can still be restricted by the rearm time of the digitizer when it is triggered by laser pulses. With our line-to-pixel referencing method, the pulse train repeats faster than the trigger rearm time can be utilized by generating a line trigger, which is phase-locked with only the first pulse in each horizontal line composing an image. Our proposed method has been tested with a pulsed laser with 40 MHz repetition rate and a commercial digitizer with a 500 ns trigger rearm time, and a frame rate of 3.73 fps with a pixel rate of 3.91 MHz was accomplished while maintaining the measurement precision under 20 ps.

Optimal design and experiment of a three-axis out-of-plane nano positioning stage using a new compact bridge-type displacement amplifier.

This paper presents the development of a new compact three-axis compliant stage employing piezoelectric actuators and a new flexure structure. A proposed stage works out-of-plane (Z, θx, θy) direction. The stage consists of 4 amplification flexures mounted piezoelectric actuators. New structure of flexure reduces height and enhances dynamic performance of stage. To certify excellent performance of the stage, comparison accomplished between conventional amplification flexure and new compact bridge type flexure. Modeling and optimal design of new type nano positioning stage performed. The optimal design is executed on the geometric parameters of the proposed flexure structure using Sequential Quadratic Programming. Experiments are carried out to verify the static and dynamic performance of the stage. The proposed out-of-plane nano-positioning stage has a Z-directional motion range 190 µm and a θx, θy-directional motion range ±2 mrad. The resolution of the stage is 4 nm, 40 nrad, and 40 nrad in the Z-, θx-, and θy-directional motions, respectively. The size of stage is 150 × 150 × 30 mm(3).

Development of 3-D poly(trimethylenecarbonate-co-epsilon-caprolactone)-block-poly(p-dioxanone) scaffold for bone regeneration with high porosity using a wet electrospinning method.

The three dimensional (3-D) poly(trimethylenecarbonate-co-epsilon-caprolactone)-block-poly(p-dioxanone) scaffold was made using a wet electrospinning method and its application as a tissue engineered matrix was evaluated for bone regeneration. The scaffold was highly porous (90%) and interconnected among pores. Under scanning electron microscopy, the cells of the center of the scaffold showed healthy well attached shape even at 4 days after seeding. The osteoblastic MC3T3-E1 cells proliferated 1.2 times faster at 4 day, 1.5 times faster at 7 days after seeding as compared with the control in the scaffold (P < 0.05). The activity of alkaline phosphatase, a bone formation marker, of cells seeded in the scaffold was nearly four times faster compared to control 28 days after seeding (P < 0.05). Taken together, newly developed 3-D poly(trimethylenecarbonate-co-epsilon-caprolactone)-block-poly(p-dioxanone) scaffold is a promising candidate for bone regeneration.