layer thickness
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AIM: To evaluate retinal nerve fiber layer thickness and retinal vascular caliber alterations in coal mine workers. METHODS: The community-based observational cross-sectional study included 4004 participants of a sub-population of the Kailuan Study. All the study participants underwent structured interviews with a standardized questionnaire, fundus photography and spectral-domain optical coherence tomography (OCT) examinations performed by trained doctors. RESULTS: The retinal nerve fiber layer thickness was significantly higher (P=0.006) and the central macular thickness was lower in coal miners (n=659, 51.0±7.8y) as compared to the control (working above the ground; n=477, 51.8±7.5y; P=0.032). Additionally, the downhole workers showed a significantly thicker retinal artery (P=0.012) and vein diameters (P<0.001). In multivariable regression, a thicker retinal nerve fiber layer was associated with a higher cumulative silica dust exposure (P=0.005) after adjusting for younger age and larger spherical equivalent. In a reverse pattern, a higher cumulative silica dust exposure (P=0.004) was significantly associated with a thicker retinal nerve fiber layer after adjusting for age, high-density lipoproteins and uric acid. Wider retinal vein diameters were associated with higher cumulative silica dust exposure (P=0.036) after adjusting for younger age and larger spherical equivalent. CONCLUSION: The retinal vessels diameters and retinal nerve fiber layer thickness are significantly thicker in long term of coal mining. The results of our study indicate that underground working environment may lead to retinal vessel dilation and inflammation. Thus, ocular examination might be needed within coal miners in order to monitor the occupational eye health as well as the incidence and progression of eye diseases.

In the present research, the AZ31 alloy is machined by wire-cut electric discharge machining (WEDM). The experiments were designed according to the Box-Behnken design (BBD) of response surface methodology (RSM). The input process variables, namely servo feed (SF), pulse on-time (Ton), servo voltage (SV), and pulse off-time (Toff), were planned by BBD, and experiments were performed to investigate the cutting rate (CR) and recast layer thickness (RCL). The analysis of variance (ANOVA) was performed to determine the influence of machining variables on response characteristics. The empirical models developed for CR and RCL were solved using Multi-Objective Particle Swarm Optimization (MOPSO). Pareto optimal front is used for the collective optimization of CR and RCL. The optimal solution suggested by the hybrid approach of RSM-MOPSO is further verified using a confirmation test on the random setting indicated by the hybrid algorithm. It is found that the minimum RCL (6.34 µm) is obtained at SF: 1700; SV: 51 V; Toff: 10.5 µs; and Ton: 0.5 µs. However, maximum CR (3.18 m/min) is predicted at SF: 1900; SV: 40 V; Toff: 7 µs; and Ton: 0.9 µs. The error percentage of ±5.3% between the experimental results and predicted solutions confirms the suitability of the proposed hybrid approach for WEDM of AZ31.

This work investigates the effect of layer thickness on the microstructure and mechanical properties of M300 maraging steel produced by Laser Engineered Net Shaping (LENS®) technique. The microstructure was characterized using light microscopy (LM) and scanning electron microscopy (SEM). The mechanical properties were characterized by tensile tests and microhardness measurements. The porosity and mechanical properties were found to be highly dependent on the layer thickness. Increasing the layer thickness increased the porosity of the manufactured parts while degrading their mechanical properties. Moreover, etched samples revealed a fine cellular dendritic microstructure; decreasing the layer thickness caused the microstructure to become fine-grained. Tests showed that for samples manufactured with the chosen laser power, a layer thickness of more than 0.75 mm is too high to maintain the structural integrity of the deposited material.

<div>In this letter, through TCAD simulations, we show that the introduction of a thin paraelectric (PE) layer between the ferroelectric (FE) and dielectric (DE) layers in an MFIS structure, expands the design space for the FE layer enabling hysteresis-free and steep subthreshold behavior, even with a thicker FE layer. This can be explained by analyzing the FE-PE stack from a capacitance perspective where the thickness of the PE layer in the FE-PE stack has the effect of reducing the FE layer thickness, while also reducing the remnant polarization. Finally, for the same FE-PE-DE stack, analog performance parameters such as $\frac{g_{m}} g_{ds}}$ and $\frac{g_{m}}{I_{d}}$ are analyzed, showing good characteristics over a wide range of gate lengths, at low drain voltages, thus demonstrating applicability for low power applications.</div>

<div>In this letter, through TCAD simulations, we show that the introduction of a thin paraelectric (PE) layer between the ferroelectric (FE) and dielectric (DE) layers in an MFIS structure, expands the design space for the FE layer enabling hysteresis-free and steep subthreshold behavior, even with a thicker FE layer. This can be explained by analyzing the FE-PE stack from a capacitance perspective where the thickness of the PE layer in the FE-PE stack has the effect of reducing the FE layer thickness, while also reducing the remnant polarization. Finally, for the same FE-PE-DE stack, analog performance parameters such as $\frac{g_{m}} g_{ds}}$ and $\frac{g_{m}}{I_{d}}$ are analyzed, showing good characteristics over a wide range of gate lengths, at low drain voltages, thus demonstrating applicability for low power applications.</div>

AbstractThe similarities between horizontal and vertical Optical Coherence Tomography (OCT) scans for the individual retinal layer thickness measurements in the macula was evaluated. Two volumetric scans (B-scans oriented horizontally and vertically) were performed in 64 multiple sclerosis subjects with history of unilateral optic neuritis and 64 healthy controls. The agreement between the thickness measurements with horizontal and vertical OCT scans was evaluated in 3 groups of eyes: healthy controls, eyes with history of optic neuritis and the fellow eyes. The mean difference in individual layer thickness between the scans was smaller than the instrument’s axial resolution in all 3 groups. The limit of agreement (LoA) varied among the different layers and sectors analyzed and this trend was similar in all the groups. For the inner retinal layers (retinal nerve fiber layer to inner nuclear layer), the inner macular sectors had a larger LoA compared to the corresponding outer sectors. In the outer plexiform and nuclear layers, the central and inner sectors (except inner temporal) had LoA larger than the other sectors and layers. The larger LoA seen for different layers and sectors suggests that the scan direction must be same for the follow-up OCT measurements and in clinical studies.

Abstract The effect of the liquid crystal (LC) layer thickness on the optical characteristics of an ultrasound LC lens was explored. Three LC lenses with differing LC layer thicknesses (100, 200, and 300 µm) were fabricated, and the optical focal lengths were measured by an optical microscope with a varying driving voltage. For the lens with a 200-µm-thick LC layer, a larger change in the focal length was observed for a smaller driving voltage compared with that of the other two lenses, indicating that the LC layer thickness is appropriate for a variable-focus lens.