Optical Scanning Research Articles

Synthesis of CdTe microstructures on p-type silicon (111) using light-modulated electrodeposition

In this paper, we present the results of our electrodeposition experiments of cadmium telluride (CdTe) microstructures on p-type silicon (111) spatially modulated by the incidence of light. This technique has shown itself to be practical and inexpensive, with immediate results. The construction from an adequate microcell to the process and all the required methodologies by such a technique are also shown. Photoelectrodeposition allows the creation of localized microdeposits, since the type of substrate used is activated locally by focalized light incidence. The photoelectrodeposited samples were characterized by optical profilometry and scanning electron microscope (SEM). The profilometry analyses showed that the deposit dimensions are directly proportional to the incident laser power but are not significantly influenced by the exposure time. The SEM has revealed information regarding the size and the concentration of the clusters on the deposited regions. The size of these agglomerates is affected by the laser intensity, showing itself higher on the center of the deposits than on the peripheral regions. Both the size of the clusters and their concentrations increase as the laser exposure time increases. Furthermore, higher concentrations of clusters are seen when linear polarization is used instead of circular polarization, but circular polarization generates larger clusters.

Laser‐Based Closed‐Loop Controlled Heat Treatment for Residual Stress Relief of Additively Manufactured AlSi10Mg Components

In laser powder bed fusion of metals small melt pools with extremely short solidification times and steep temperature gradients to the surrounding material exist due to the layer‐wise and selective melting process with small areas of energy input compared to the cooler, solid ambient material. This causes high thermally induced residual stresses (RS), which can lead to the immediate rejection of the component due to critical part deformation and inhomogeneous mechanical properties under load. To prevent this, furnace‐based stress relief heat treatments are commonly applied before cutting‐off the part from the built platform. In this study a novel closed‐loop controlled laser‐based heat treatment using temperature feedback through inline pyrometer measurement is investigated, enabling a fast and highly efficient postprocess stress relief. Therefore, a laser beam is guided by a scanner optics in a meandering pattern over the top surface of AlSi10Mg cantilever specimens. It enables a decrease of near‐surface RS from 158 to 5 N mm−2, resulting in a reduction of displacement by over 90% at material affecting depths up to 3 mm and area rates of 8 to 163 mm2 s−1.

A Novel Grid Strategy for Correlating Focal Macular Anatomic Changes With Focal Changes in Choriocapillaris Perfusion.

To establish the repeatability of choriocapillaris flow deficit (CCFD) measurements within a macular grid and then demonstrate the use of this registered grid strategy to follow CCFD measurements over time. Swept-source optical coherence tomography angiography scans were acquired (nominal size of 6 × 6mm). For each scan, masks of hyperreflective foci, calcified drusen, and persistent choroidal hypertransmission defects (hyperTDs) were generated. These masks were then used to exclude these prespecified regions when calculating the CCFD percentages (CCFD%). Scans were registered, and CCFD% measurements were performed within 3-mm and 5-mm fovea-centered circles and within a fovea-centered grid (one box: 74 × 74 pixels). The 95% minimal detectable changes (MDC95) for CCFD% were calculated for each of the regions. This longitudinal grid workflow was then used to study eyes before and after drusen resolved. Ninety eyes of 63 patients were identified: 30 normal eyes, 30 eyes with intermediate age-related macular degeneration (iAMD), and 30 eyes with hyperTDs. The MDC95 for the normal, iAMD, and hyperTD eyes within the 3-mm and 5-mm circles ranged from 0.85% to 1.96%. The MDC95 for an individual grid's box ranged from 3.35% to 4.67%, and for the total grid area, the MDC95 ranged from 0.91% to 1.40%. When tested longitudinally before and after the resolution of drusen using grid strategy, no significant differences in the CCFD% were observed. A grid strategy was developed to investigate targeted longitudinal changes in CCFD% associated with changes in optical coherence tomography biomarkers, and this strategy was validated using eyes in which drusen resolved.

Wear Behavior of 2024 Aluminum Alloy Reinforced with SiC Particles

The wear behavior of Aluminum Alloy (AA) 2024 reinforced with SiC particles were investigated at room conditions. Stir casting method was used to prepare the matrix composite of AA 2024 alloy reinforced with different weight percentages of SiC (3, 6, 9, 12 wt%). The wear behavior of both AA 2024 and AA 2024/SiC composite was studied using the reciprocating wear test. Loads of 2.5, 5, 7.5, 10, and 12.5 N were applied with sliding speeds of .0.55, 0.72, 0.88, 1.04 and 1.2 m/sec in dry sliding contact conditions. The microstructure and phase distribution were investigated using Optical Microscope (OM) and Scanning Electron Microscopy (SEM). The results demonstrate the presence of fine dendritic structure with semi-homogeneously distributed SiC particles in the alloy matrix. The micro-hardness increased with increasing SiC percentage. The highest value of hardness of 79.3 HV was found at 12 wt% SiC, from the initial 44 HV of the base alloy. The wear tests showed that the wear rate increased with increasing applied normal contact load at a contact sliding speed of 0.88 m/sec. The wear rate of the as cast material was 18.59 ×10-8 g/cm. Adding the SiC particles decreased the wear rate to 13.78, 9.76, 7.98, and 5.81 ×10-8 g/cm for 3, 6, 9, 12 wt% SiC addition at 12.5 N applied load, respectively. SEM examination of worn surfaces showed that severe and abrasive wear was exhibited at higher loads in the dry case while mild and adhesive wear were observed at lower loads in the lubricated condition.

A Fast flatness deviation evaluation algorithm for point cloud data

This paper proposes and develops a novel method, namely the Partially Iterative Algorithm (PIA), for high-speed assessment of flatness deviation for point cloud data, which is typically measured data obtained by advanced instruments for precision manufacturing, such as optical scanners and industrial computed tomography. Firstly, an enhanced flatness deviation model is established based on the minimum zone principle, which is strictly adhered to the latest ISO definition. Secondly, the proposed method is detailed, including the Dynamic Point Set (DPS), the update scheme, and the terminal condition. Thirdly, comparisons are conducted with typical methods for flatness deviation assessment, along with a practicability test via the simulated dataset and measuring dataset. The results show that the proposed methods can accurately and rapidly assess flatness deviation on point cloud data with massive measuring points.

Glaucoma Clinic Monitoring Over 6 Months Using Online Circular Contrast Perimetry in Comparison with Standard Automatic Perimetry: The Developing-World Setting.

Online circular contrast perimetry provides visual field testing on any computer or tablet without additional hardware. This study compared outcomes of online circular contrast perimetry (OCCP) and standard automated perimetry (SAP) in a developing world setting. The longitudinal and observation study was conducted on patients sampled during 2023 at Hanoi Medical University Hospital. Participants were either healthy volunteers as controls or stable glaucoma patients with either primary angle closure or primary open-angle glaucoma. They underwent a comprehensive ocular examination, retinal nerve fiber layer optical coherence tomography scan, and visual field tests performed at baseline and after 3 months and 6 months, using OCCP and SAP in clinic. The current study was carried out in 168 eyes of 87 patients at baseline, 133 eyes of 69 patients at 3 months, and 121 eyes of 63 patients at 6 months. At baseline, OCCP mean deviation (MD) (R2 = 0.804, p < 0.001) and visual index (VI) (R2 = 0.892, p < 0.001) were strongly correlated with SAP MD and visual field index (VFI) respectively. There was strong agreement and correlation between MD and VI/VFI for SAP and OCCP on repeated testing after 6 months. At 6 months AUC of SAP VFI (0.79) was superior to AUC of OCCP VI (0.67, p = 0.036); otherwise there was no difference in AUC of MD or VI/VFI at baseline, 3 and 6 months, when comparing OCCP and SAP. OCCP parameters are significantly correlated with those of SAP. OCCP has the potential to provide a complementary role to SAP in glaucoma screening and monitoring.

Electrospinning of Cellulose Benzyl Carbamates for Enantioselective Membrane Filtration.

Electrospun nanofibrous membranes made of chiral selectors (CSs) have shown their potential for efficient chiral resolutions via filtrations. It is thus of great importance to expand the number of electrospun membranes made of various CSs for the resolution of a wide range of chiral compounds. Here, the electrospinning of two benzyl carbamate derivatives of cellulose, namely cellulose benzyl carbamate (CBzC) and cellulose 4-chlorobenzyl carbamate (CCBzC), to form a new type of enantioselective membranes for chiral resolutions of racemic compounds, is reported. The morphology of the electrospun membranes is studied by optical microscopy and scanning electron microscopy in relation to the electrospinning process parameters. Liquid-liquid permeation experiments of the racemic compounds, (R,S)-1-(1-naphthyl)ethanol ((R,S)-NET), (R,S)-1,1'-bi-2-naphtol ((R,S)-BNP), (R,S)-naproxen ((R,S)-NAP), and (R,S)-benzoin ((R,S)-BNZ) through the membranes demonstrate preferable permeations of (R)- or (S)-enantiomers depending on the combinations between the CSs and the racemates. Molecular docking simulations indicate the differences in the binding type, number, and free energies between the CSs and the enantiomers.

Wear performance enhancement of interface layer in CMT-WAAM fabricated ER4043/ER5356 Bimetallic wall through Friction Stir Surface Treatment

Abstract The cold metal transfer (CMT) based wire arc additive manufacturing (WAAM) technique has limited wear applications compared to other manufacturing methods due to its lower wear resistance. However, integrating friction stir processing (FSP) with WAAM can enhance mechanical or wear performance, making it a promising and reliable manufacturing process for aerospace, automotive, and marine applications. In this work, CMT-WAAM technique has been used to fabricate a bimetallic wall of aluminium alloys (ER4043/ER5356), employing a bidirectional depositional strategy. The impact of FSP on the interface layer of the WAAM wall, serving as a post-processing treatment on the wall's surface, is studied in terms of microstructure and microhardness. Additionally, a pin-on-disk wear test is performed on the interface layer of both WAAM and FSP-treated WAAM walls under loads of 20N, 30N, and 40N. Results from optical and Field emission scanning electron microscopy (FESEM) microstructures revealed the grain refinement in the stirred zone, with a higher wt. % of Mg through Energy Dispersive Spectrometer (EDS) analysis. X-ray diffraction (XRD) identifies various intermetallic compounds, including Al12Mg17, Al3.21Si0.47, and Mg2Si, with higher peak intensities in the FSP-treated wall. Electron Backscatter Diffraction (EBSD) analysis indicates a decrease in the average grain size of stirred area, which is ~72.40 µm in unstirred area and ~5.57 µm in stirred area due to the local strain concentration effect during FSP. Grain refinement during FSP leads to an increase in average hardness by 35.9%. The wear rate and coefficient of friction (COF) get reduced, credited to high-temperature dynamic recrystallization and continuous grain recovery in FSP. Scanning electron microscope (SEM) analysis of worn surfaces highlights abrasion, delamination, and adhesion as significant wear mechanisms.

Electrostatic MEMS Two-Dimensional Scanning Micromirrors Integrated with Piezoresistive Sensors

The MEMS scanning micromirror requires angle sensors to provide real-time angle feedback during operation, ensuring a stable and accurate deflection of the micromirror. This paper proposes a method for integrating piezoresistive sensors on the torsion axis of electrostatic MEMS micromirrors to detect the deflection angle. The design uses a multi-layer bonding process to realize a vertical comb-driven structure. The device structure is designed as a double-layer structure, in which the top layer is the ground layer and integrates with piezoresistive sensor. This approach avoids crosstalk between the applied drive voltage and the piezoresistive sensor. This design also optimizes the sensor’s size, improving sensitivity. A MEMS two-dimensional (2D) scanning micromirror with a 1 mm mirror diameter was designed and fabricated. The test results indicated that, in a vacuum environment, the torsional resonance frequencies of the micromirror’s fast axis and slow axis were 17.68 kHz and 2.225 kHz, respectively. When driving voltages of 33 V and 40 V were applied to the fast axis and slow axis of the micromirror, the corresponding optical scanning angles were 55° and 45°, respectively. The piezoresistive sensor effectively detects the micromirror’s deflection state, and optimizing the sensor’s size achieved a sensitivity of 13.87 mV/V/°. The output voltage of the piezoresistive sensor shows a good linear relationship with the micromirror’s deflection angle, enabling closed-loop feedback control of the electrostatic MEMS micromirror.

Homonymous hemi-macular atrophy in multiple sclerosis

Background: Retrograde trans-synaptic degeneration (TSD) following retro-chiasmal pathology, typically retro-geniculate in multiple sclerosis (MS), may manifest as homonymous hemi-macular atrophy (HHMA) of the ganglion cell/inner plexiform layer (GCIPL). Objective: To determine the frequency, association with clinical outcomes, and retinal and radiological features of HHMA in people with MS (PwMS). Methods: In this cross-sectional study, healthy controls (HC) and PwMS underwent retinal optical coherence tomography scanning. For quantitative identification of HHMA, a normalized asymmetry ratio was used, and its normative cutoffs were established from the HC. HHMA PwMS were propensity score matched 1:2 to non-HHMA PwMS. Mixed-effects linear regression models were used in analyses. Results: Based on normative data from 238 HC (466 eyes), 79 out of 942 PwMS exhibited HHMA (8.4%; 143 eyes). Compared to non-HHMA eyes from matched PwMS (158 PwMS; 308 eyes), HHMA eyes had lower average GCIPL (diff: −5.7 μm (95% CI −7.6 to −3.8); p < 0.001) but also inner nuclear layer (diff: −0.9 μm (95% CI −1.6 to −0.1); p = 0.02), and outer nuclear layer (diff: −1.9 μm (95% CI −3.4 to −0.4); p = 0.02) thicknesses; in further analyses, these differences were exclusive to the homonymous side of HHMA. HHMA participants also exhibited higher expanded disability status scale scores (diff: 0.5 (95% CI 0.1 to 0.9); p = 0.02), worse 100% and 2.5% visual acuity scores (diff: −3.2 (95% CI −4.1 to −1.0); p = 0.002, −5.4 (95% CI −7.5 to −3.5); p < 0.001), and higher frequency of microcystoid macular changes (10.1% vs. 3.2%; p = 0.03) compared to non-HHMA participants. Conclusions: HHMA, possibly as a marker of TSD, may signify higher disability in MS.

Mesh Smoothing of 3D Prosthesis and Orthosis Models

Introduction. Formation of a contact surface in prosthetics and orthotics is crucial for the restoration of human musculoskeletal functions. This paper considers specific features of methods currently used for denoising of a 3D model surface obtained by optical scanning. An algorithm for manufacturing an individual prosthetic and orthopedic product is developed. The current literature reports no similar methods, which may be explained by the widespread use of gypsum technology for the manufacture of prostheses and orthoses.Aim. Research and development of digital filtration methods for 3D meshes obtained by optical scanning for further modeling of individual prosthesis and orthosis modules.Materials and methods. It is proposed to optimize the pre-processing stage of 3D scanned models by applying denoising and smoothing processes. In total, 50 optical 3D scans were selected for testing via the following denoising algorithms: bilateral filtering, vertex-based anisotropic smoothing, mean and median filtering applied to face normals.Results. The study was conducted using 3D scans of lower limb stumps and Chenault brace orthoses and corsets provided by the Institute of Prosthetics and Orthotics, Albrecht Federal Scientific and Educational Centre of Medical and Social Expertise and Rehabilitation. А method for denoising and smoothing of the 3D model surfaces for the manufacture of prosthetic and orthopedic products is proposed. The SNR metric difference SNR – δ-SNR (with averaging by scans and SNR values) and average execution time were calculated. The bilateral filtration method with δ-SNR = 11.3362 dB and a runtime of 8.8900 s showed the highest efficiency.Conclusion. The proposed methods for the pre-processing stage of 3D optical scans showed high efficiency in the formation of 3D models of prosthesis and orthosis modules. The results obtained can be used for automating the process of manufacturing various prosthetic and orthopedic products, which is particularly relevant in the context of the modern geopolitical situation.

Three-Dimensional Choroidal Vessels Assessment in Age-Related Macular Degeneration.

To compare the choroidal vasculature in eyes with early- and intermediate-stage age-related macular degeneration (dAMD) and healthy using a novel three-dimensional algorithm. Patients with dAMD and healthy controls underwent clinical examinations and swept-source optical coherence tomography scans (PlexElite-9000 device) centered on the fovea. Scans with quality scores >6 were included. Eyes with any signs of neovascular AMD or geographic atrophy were excluded. The choroidal layer was segmented using ResUNet model and volumetric smoothing. Phansalkar thresholding was used to binarize the choroidal vasculature. The three-dimensional maps were divided into five sectors. The three largest vessels in each sector were measured to determine the mean choroidal vessel diameter (MChVD) and inter-vessel distance (IVD). Volumetric choroidal thickness (ChT) and vascularity index (CVI) were also calculated. This retrospective cross-sectional study analyzed 60 eyes from 45 dAMD patients (27 early-stage, 33 intermediate-stage) and 26 eyes from 16 healthy controls. The average MChVD was increased in dAMD eyes compared to healthy eyes (239.559 ± 47.058 µm vs. 197.873 ± 49.047 µm, P < 0.001). The average MChVD in each sector increased significantly in eyes with dAMD (P < 0.05). The average IVD was increased significantly in dAMD eyes compared to healthy eyes (234.128 ± 69.537 µm vs. 179.914 ± 49.995 µm, P < 0.001). The average IVD in each sector was significantly increased in eyes with dAMD (P < 0.05). Average ChT and CVI in dAMD were reduced compared to healthy eyes (P < 0.05). Eyes with dAMD demonstrated increased MChVD and IVD and decreased ChT and CVI, possibly related to smaller-vessel atrophy and larger-vessel dilation.

Magnesium-based bioresorbable flow diverter for intracranial aneurysms: a pilot study of biocompatibility and bioresorption in a rabbit vascular model

BackgroundBioresorbable flow diverters (BRFDs) have the potential to solve several problems associated with conventional permanent flow diverters. We have constructed bare and poly-L-lactic acid (PLLA)-coated magnesium BRFDs (MgBRFDs) using a...

Three-point-supported 2-DOF large-area tilting mirror inspired by a playground facility.

In this paper, we demonstrate a three-point-supported 2D optical scanner designed to enhance the field of view (FoV) and optical scanning angles, and facilitate the development of large mirrors (>10c m). By integrating fused deposition modeling (FDM) 3D printing with electromagnetic driving, we present a cost-effective, large-sized scanning mirror with two-dimensional scanning capabilities. The mirror has an area of 144c m 2, enabling greater light capture for enhanced scanning performance. Under DC driving, the maximum optical scanning angles are 5.99° in the x direction and 12.61° in the y direction. For AC driving, the resonant scanning frequencies are 18.2Hz for the x scan and 19Hz for the y scan, with maximum scanning angles of 7.87° for the x scan and 7.19° for the yscan.

Investigation of mechanical and electrical properties of photopolymer nanocomposites reinforced with carbon‐based nanoparticles produced by digital light processing 3D printing technique

AbstractDigital Light Processing (DLP) techniques are being increasingly investigated to create advanced composite materials with improved properties by incorporating a variety of nanoparticles. In this study, the mechanical and electrical properties of photopolymer nanocomposite materials reinforced with carbon‐based nanoparticles produced by DLP were investigated. The nanocomposites were produced by incorporating varying proportions of Multi‐Walled Carbon Nanotubes (MWCNT), reduced Graphene Oxide (rGO), and combinations of Carbon Black and Carbon Nanotubes (CB/CNT) into the photopolymer matrix. The mechanical properties of the nanocomposites were assessed by tensile testing, while their electrical conductivity was determined using the four‐point probe technique. This study was the first to investigate the most effective concentrations of three distinct carbon‐based nanoparticles and the impact of their homogeneous distribution on the performance of composites with a holistic approach. The morphological analysis of the composites, conducted using optical microscopy and Scanning Electron Microscopy (SEM), revealed the critical role of nanoparticle distribution in determining composite properties. The findings indicate that the incorporation of nanoparticles at low proportions (up to 0.5 wt%) resulted in a significant improvement, with up to an 82% increase in the ultimate tensile strength of the photopolymer. Nevertheless, as the nanoparticle ratio increased, a rise in material brittleness and a decrease in mechanical strength were observed. On the other hand, electrical conductivity showed a significant increase when the percolation threshold was exceeded in the composites reinforced with MWCNT (0.5%wt) and CB/CNT (0.75%wt).Highlights The properties of DLP composites with carbon nanoparticles are investigated. SEM analysis shows nanoparticle dispersion's key role in composite performance. 0.5% rGO reinforcement boosts tensile strength by up to 82%. Conductivity surges at 0.5% MWCNT, surpassing the percolation threshold. High nanoparticle ratios increase composite brittleness.

A novel multicomponent micro-alloyed magnesium for orthopaedic applications: a microstructural, mechanical, degradation and bioactivity study

ABSTRACT The current study focuses on development of magnesium based micro-alloy with the composition of Mg–0.5Zn–0.15Ca–0.1Mn–0.1Sn–0.1Ag–0.2Ce–0.2Sr using casting method. Microstructural examinations conducted using optical microscopy and scanning electron microscopy (SEM) unveiled a uniform grain distribution in the alloy with minimal intermetallic content, corroborated by X-ray diffraction (XRD) analysis matching the magnesium peak precisely. Tensile testing indicated that the solution strengthening process boosted the alloy’s required yield strength and stiffness, while enhancing magnesium’s ductility up to 19.07% elongation. Electrochemical tests demonstrated an outstanding corrosion resistance rate of 0.91 mm/year, supported by Nyquist plots indicating passivation behaviour and film formation. The pH variations revealed an initial spike to 8.13 within the first 24 hours, gradually declining thereafter. The bioactivity assessment of the developed alloy showcased the formation of near-stoichiometric apatite layers on the alloy surface, confirming its potential as a suitable orthopaedic implant material.

Influence of core fluorination on the phase properties of fan-like azobenzene based supramolecules, their cis-trans photoisomerization and photoluminescence dynamics

The stimuli-responsive, low molecular weight, dynamically tunable photophysical features have long been an important objective that challenges chemists in synthesizing liquid crystal (LC) compounds. Herein, the effect of core fluorination on the mesomorphic behavior of fan-like azobenzene derivatives was reported. Two new series of azobenzene derivatives which differ from each other in the length of the terminal alkoxy side chain as well as fluorine (-F) group substitution on the azobenzene moiety were synthesized (3a-3c, 4a-4c) and molecular structures of the compounds were confirmed using various analytical techniques. Absorption spectra of the LC compounds 3b and 3c are characterized by ππ∗ transitions around 350–410 nm. The self-assembly of these LC compounds was investigated using polarized optical microscope (POM) and differential scanning colorimetry (DSC). The trans-to-cis photoisomerization of the LC compounds 3b and 3c occurs in these absorption bands. The trans-to-cis photoisomerization of LC compounds 3b and 3c showed 4 h and 24.5 h whereas, thermal cis-to-trans isomerization rates were found to be 90s and 100s resulting in tuning of mesophases. Room temperature photoluminescence (RTPL) of LC compounds 3b and 3c when excited at 220 nm, 230 nm and 240 nm showed several sharp/weak emission intensity bands. Both the LC compounds (3b, 3c) showed sharp blue emission bands and yellow/green/orange colored bands correspond to weak emission spectra when excited at 220 nm. Further, steady state photoluminescence (SSPL) spectra of these both LC compounds revealed sharp near edge emission bands and broad violet emission peaks with higher Stoke's shift as well as full width half maximum (FWHM). Fluorescence lifetime decay (FLD) studies of compound 3 b unveiled an average lifetime (τ) shuttle between 17.24 ns and 103.60 ns at various excitation wavelengths. However, FLD of LC compound 3c unveiled that the τ fluctuates between 27.00 ns and 102.56 ns at various excitation wavelengths. Quantum yield (QY) decreases for both the LC compounds with an increase in excitation wavelengths. The study proved the importance of the alkoxy side chain at one end of the aromatic ring and core fluorination as a significant tool to modify the LC behavior of azobenzene derivatives. Thus, synthesized azobenzene derivatives are potentially useful for developing permanent optical storage and display devices.

Paramagnetic rim lesions are associated with inner retinal layer thinning and progression independent of relapse activity in multiple sclerosis.

Paramagnetic rim lesions (PRLs) are chronic active lesions associated with a severe disease course in multiple sclerosis (MS). This study was undertaken to investigate an association between retinal layer thinning (annualized loss of peripapillary retinal nerve fiber layer [aLpRNFL] and ganglion cell-inner plexiform layer [aLGCIPL]) and PRLs in patients with MS (pwMS). In this study, pwMS with brain magnetic resonance imaging and ≥2 optical coherence tomography scans were included. Cox proportional hazard regression models were performed using progression independent of relapse activity (PIRA) as the dependent variable, and aLpRNFL, aLGCIPL, or the number of PRLs as independent variables, adjusted for covariates. We analyzed data from 97 pwMS (mean age = 35.2 years [SD = 9.9], 71.1% female, median disease duration = 2.3 years [interquartile range = 0.9-9.0]). The number of PRLs was associated with aLpRNFL and aLGCIPL. PIRA was observed in 18 (18.6%) pwMS, with aLpRNFL (hazard ratio [HR] = 1.44 per %/year), aLGCIPL (HR = 1.61 per %/year), and the number of PRLs (HR = 1.24 per PRL) being associated with increased risk of PIRA. The number of PRLs is associated with inner retinal layer thinning and increased risk of PIRA. A combination of PRLs and retinal layer thinning could serve as a surrogate for pwMS at highest risk of disability progression.

Effect of Electrofriction Treatment on Microstructure, Corrosion Resistance and Wear Resistance of Cladding Coatings

In recent years, the issue of increasing the wear resistance of the working bodies of agricultural machinery designed for cutting and breaking the soil has received special attention. The surface layers of working bodies of agricultural machinery during operation are subjected to intensive abrasive wear, which leads to rapid wear of equipment and a reduction in its service life. The induction cladding method using materials such as Sormait-1 is widely used to increase the wear resistance of tool working surfaces. However, after coating, additional heat treatment is required to improve the physical and mechanical properties of the material and increase its durability. In electrofriction technology (EFT) hardening, the surfaces of the parts are subjected to melting under the influence of electric arcs. In this work, three types of surface treatment of L53 steel have been investigated: induction cladding using Sormait-1, electrofriction treatment, and a combination of induction cladding followed by electrofriction treatment. The microstructure was analyzed using optical microscopy and scanning electron microscopy. Erosion and abrasion tests were carried out in accordance with ASTM G65 and ASTM G76-04 international standards to evaluate the wear resistance of the materials under mechanical stress. A dendritic structure was formed after the induction cladding of the Sormait-1 material, but subsequent electrofriction treatment resulted in a reduction of this dendritic structure, which contributed to an increase in the hardness of the material. However, the highest hardness, reaching 965 HV, was recorded after electrofriction treatment of L53 steel. This is explained by needle martensite in the structure, which is formed as a result of quenching. Further, the influence of structural characteristics and hardness on erosion and abrasion wear resistance was examined. The analysis showed that the material microstructure and hardness have a decisive influence on the improvement of wear resistance, especially under conditions of intensive erosion and abrasive friction.

SECONDARY MINERAL FORMATION IN PRODUCTIVE DEPOSITS OF THE PASHIYSKY HORIZON OF THE SOUTH TATAR ARCH (REPUBLIC OF BASHKORTOSTAN)

The article presents the results of studying the postsedimentary mineralization of productive terrigenous deposits of the Pashiysky horizon of the South Tatar arch. The authors' research was carried out on the basis of a large amount of core material from newly studied wells with the involvement of wells from the archival fund. The analytical work included the following methods: classical optical microscopy and scanning electron microscopy (SEM). Using these methods, the main types of secondary mineral formation, the form and nature of the allocation of authigenic minerals that form secondary cement were studied, and an assessment of the degree of their influence on the filtration-capacitive properties (FPP) was given. It is shown that sideritization is a fairly common phenomenon in the studied deposits, but it does not have a significant effect on the reduction of the reservoir properties of productive deposits. Detailed optical and mineralogical studies have shown that authigenic siderite in the studied rocks is presented in various forms (spherites, spherulites, oolites and granular grains) and is mostly found in silt varieties. In productive sandstones, an insignificant decrease in the reservoir properties can only be associated with expanding rims in siderite spherites. As shown by the study of the composition of these rims, they are composed mainly of ankerite, in places they contain mangano-siderite. In some samples of the Pashiysky horizon, partial replacement of siderite by iron hydroxides was observed; in isolated wells, thin layers of oolitic siderite-ferruginous rocks were encountered. It was shown that the main influence on the reduction of the filtration-capacity properties of the studied sediments is secondary silification and carbonatization. At the same time, secondary quartz is developed mainly in water-saturated sandstones and heterogeneous silt-sandstones, and, as a rule, is distributed mostly locally. Secondary silica is observed in the form of regeneration rims, xenomorphic grains and is deposited on the walls of pores and channels. A significant effect on the reduction of the porosity and permeability parameters of the productive sandstones of the Pashiysky horizon of the South Tatar arch is exerted by secondary crystalline calcite or dolomite island cement of the basal, basal-pore and poikillite type.