Visual Stability Research Articles

Mechanical properties and microstructural characterization of ferrock as CO2–negative material in self-compacting concrete

The construction industry is one of the major sources of pollution and global warming, with the utilization of cement being a significant contributor. This study aimed to minimize cement usage in construction while maintaining overall strength through the development of sustainable and eco-friendly concrete. A self-compacting concrete (SCC) was created by replacing cement with eco-friendly ferrock, aggregates and superplasticizers at levels of 5%, 10%, 15%, 20% and 25%. The optimal blend was determined based on fresh and mechanical behaviour parameters. Rheological analysis of the fresh concrete was conducted using L-box, Slump cone, V-funnel equipment and visual stability index. The SCC was then cured through water immersion, CO2 exposure and a combination of both. The performance of the ferrock SCC was evaluated under different curing conditions to determine its hardened and microstructural properties. The addition of ferrock altered the properties of the concrete, and changing the curing method also influenced the behaviour of the hardened concrete. CO2 curing achieved about 40% of the concrete strength within four hours, while combined water and CO2 curing produced higher-quality concrete, as shown by UPV, SEM, and XRD results. The incorporation of ferrock almost doubled the strength of the concrete in combined curing. At an optimum replacement level of 10%, the compressive strength values of water, CO2, and combined curing increased by 21.9%, 25.9% and 32.6%, respectively, after 28 days. The bond strength also increased by 20% at this level of ferrock addition for combined curing. Comparison with normal SCC indicated that the ferrock-based SCC was physically stronger at an optimum replacement level of 10%, with a higher degree of compaction and dense matrix. These findings suggest the superiority of ferrock SCC, which offers potential for use in future construction.

Bayesian and Discriminative Models for Active Visual Perception across Saccades.

The brain interprets sensory inputs to guide behavior, but behavior itself disrupts sensory inputs. Perceiving a coherent world while acting in it constitutes active perception. For example, saccadic eye movements displace visual images on the retina and yet the brain perceives visual stability. Because this percept of visual stability has been shown to be influenced by prior expectations, we tested the hypothesis that it is Bayesian. The key prediction was that priors would be used more as sensory uncertainty increases. Humans and rhesus macaques reported whether an image moved during saccades. We manipulated both prior expectations and levels of sensory uncertainty. All psychophysical data were compared with the predictions of Bayesian ideal observer models. We found that humans were Bayesian for continuous judgments. For categorical judgments, however, they were anti-Bayesian: they used their priors less with greater uncertainty. We studied this categorical result further in macaques. The animals' judgments were similarly anti-Bayesian for sensory uncertainty caused by external, image noise, but Bayesian for uncertainty due to internal, motor-driven noise. A discriminative learning model explained the anti-Bayesian effects. We conclude that active vision uses both Bayesian and discriminative models depending on task requirements (continuous vs categorical) and the source of uncertainty (image noise vs motor-driven noise). In the context of previous knowledge about the saccadic system, our results provide an example of how the comparative analysis of Bayesian versus non-Bayesian models of perception offers novel insights into underlying neural organization.

Surface modification of cellulose nanocrystals by physically adsorbing lactoferrin as pickering stabilizers: Emulsion stabilization and in vitro lipid digestion

Surface modification is a prerequisite procedure for using cellulose nanocrystals (CNCs) in food and other industries. This study reports a simple and safe procedure for CNCs surface modification using physically absorbing food protein (lactoferrin, LF) that could improve the emulsification performance and modulating emulsion lipid digestion in vitro. Modification of CNCs by LF was characterized by adsorption percentage (%), zeta-potential, atom force microscopy, and contact angle. The modification occurred electrostatically between negatively CNCs and positively LF. LF-modified CNCs are more hydrophobic and aggregation-prone depending on the ratio of protein to CNCs and pH. Emulsions stabilized by LF-modified CNCs which are characterized by visual appearance, microstructure, droplet size, and stability against lipid oxidation. Modification of CNCs by LF could improve the emulsification performance of CNCs and show high stability against lipid oxidation. In vitro gastrointestinal digestion of emulsions stabilized by LF-modified CNCs was also investigated by Free fatty acid released (FFA, %) and microstructure. Overall, emulsions stabilized by CNCs particles have lower lipid digestion extent than that of tween 20. The findings would have potential applications in fabrication of novel functional emulsions in food and other industries.

Evaluation of Visual Outcomes and 3-Month Refractive Stability of a New Hydrophobic Acrylic Intraocular Lens.

To determine the refractive stability of a new hydrophobic acrylic intraocular lens (IOL) when implanted bilaterally. This was a prospective, evaluator masked, single surgeon study of 58 eyes of 29 patients. Patients were bilaterally implanted with the Clareon monofocal IOL (CNA0T0, Alcon Vision LLC). Refractive stability was evaluated between 1 and 3 months postoperatively. At 3 months postoperatively, data were also collected for binocular uncorrected and distance corrected visual acuities at distance (4 m) and intermediate (80 cm and 66 cm) and binocular defocus curve. Postoperative refraction was statistically equivalent between 1 and 3 months postoperatively (p < 0.001). Mean postoperative uncorrected distance visual acuity was -0.01 ± 0.10 logMAR, and mean corrected distance visual acuity was -0.04 ± 0.06 logMAR. Mean postoperative uncorrected intermediate visual acuity was 0.16 ± 0.13 logMAR and 0.24 ± 0.14 logMAR at 80 cm and 66 cm, respectively. With distance correction in place, mean visual acuity at 80cm and 60cm was 0.16 ± 0.13 logMAR and 0.23 ± 0.14 logMAR, respectively. The Clareon monofocal IOL can provide stable refraction, excellent distance vision, and functional intermediate vision postoperatively.

Effect of fine aggregate/coarse aggregate ratio on the fresh and hardened properties of self compacting concrete

This study examines the effect of the fine-to-coarse aggregate ratios on the fresh properties and mechanical properties of self-compacting concrete (SCC). The mixture design was guided to highlight the changes in the behavior of SCC in terms of; flowability, relative viscosity, stability, compressive strength, splitting strength, and flexural strength. Three ratios of fine-to-coarse aggregate were used: ratio 1; 44%: 56%, ratio 2; 47%: 53%, and ratio 3; 50%: 50%. Results indicate that the slump flow increases with the increase in the coarse aggregate content. Stability, slump flow, are relative viscosity are the key parameters that govern the behavior of fresh concrete. The ratio 47% fine to 53% coarse satisfied those parameters and recorded 680 mm slump flow with t50 equals 3.6 sec. The visual stability index was 0, which indicates the high stability of this mix. An excellent correlation (R2 = 1) was found between the viscosity index (t50) and V-funnel time (tv). The compressive strength of ratio 1 was 79.4 MPa, and slightly increased to 81.5 MPa and 83.4 MPa for ratio 2 and 3, respectively. The splitting tensile strength was found to be 8% of the compressive strength, and the flexural strength was 19% of the compressive strength for all ratios.

Laminar mechanisms of saccadic suppression in primate visual cortex

Saccadic eye movements are known to cause saccadic suppression, a temporary reduction in visual sensitivity and visual cortical firing rates. While saccadic suppression has been well characterized at the level of perception and single neurons, relatively little is known about the visual cortical networks governing this phenomenon. Here we examine the effects of saccadic suppression on distinct neural subpopulations within visual area V4. We find subpopulation-specific differences in the magnitude and timing of peri-saccadic modulation. Input-layer neurons show changes in firing rate and inter-neuronal correlations prior to saccade onset, and putative inhibitory interneurons in the input layer elevate their firing rate during saccades. A computational model of this circuit recapitulates our empirical observations and demonstrates that an input-layer-targeting pathway can initiate saccadic suppression by enhancing local inhibitory activity. Collectively, our results provide a mechanistic understanding of how eye movement signaling interacts with cortical circuitry to enforce visual stability.

Visual function and biofeedback training of patients with central vision loss: a review.

Older individuals with macular diseases, such as age-related macular degeneration, experience central vision loss (CVL) due to degeneration of their photoreceptors and retinal cells. Patients with CVL may experience various vision impairments, including of visual acuity, fixation stability, contrast sensitivity, and stereoacuity. After CVL, most patients develop a preferred retinal locus outside the affected macular region, which serves as a new visual reference. In this review, we provide an overview of the visual function and impairment in individuals with CVL. In addition, the important role of biofeedback training on the visual function and activity of individuals with CVL is also reviewed. Accordingly, the location and development of the preferred retinal loci are discussed. Finally, this review discusses how to conduct biofeedback training to treat individuals with CVL.

Vestibular prosthesis: from basic research to clinics.

Balance disorders are highly prevalent worldwide, causing substantial disability with high personal and socioeconomic impact. The prognosis in many of these patients is poor, and rehabilitation programs provide little help in many cases. This medical problem can be addressed using microelectronics by combining the highly successful cochlear implant experience to produce a vestibular prosthesis, using the technical advances in micro gyroscopes and micro accelerometers, which are the electronic equivalents of the semicircular canals (SCC) and the otolithic organs. Reaching this technological milestone fostered the possibility of using these electronic devices to substitute the vestibular function, mainly for visual stability and posture, in case of damage to the vestibular endorgans. The development of implantable and non-implantable devices showed diverse outcomes when considering the integrity of the vestibular pathways, the device parameters (current intensity, impedance, and waveform), and the targeted physiological function (balance and gaze). In this review, we will examine the development and testing of various prototypes of the vestibular implant (VI). The insight raised by examining the state-of-the-art vestibular prosthesis will facilitate the development of new device-development strategies and discuss the feasibility of complex combinations of implantable devices for disorders that directly affect balance and motor performance.

Unveiling the time course of visual stabilization through human electrophysiology

Object positions are coded relative to their surroundings, presumably providing visual stability during eye movements. But when does this perceived stability arise? Here we used a visual illusion, the frame-induced position shift, and measured electrophysiological activity elicited by an object whose perceived position was either shifted because of a surrounding frame or not, thus dissociating perceived and physical locations. We found that visually evoked responses were sensitive to only physical location earlier in time (∼70ms), but both physical and illusory location information was present at a later time point (∼140ms). Furthermore, location information could be reliably decoded across physical and illusory locations during the later time interval but not during the earlier time interval, demonstrating that neural activity patterns are shared between the two processes at a later stage. These results suggest that visual stability of objects emerges relatively late and is thus dependent on recurrent feedback from higher processing stages.

Comparison Between Pulsed and Continuous Accelerated Corneal Cross-Linking Protocols.

To compare between two accelerated corneal cross-linking (A-CXL) protocols in the management of keratoconus (KC) as regard to the extent of corneal treatment. This retrospective, comparative study included patients having mild to moderate, progressive KC. The study population was divided into two groups; group 1 enrolled 103 eyes of 62 patients who received pulsed light A-CXL (pl-CXL) at a power of 30 mW/cm2 with an irradiation time of 4 minutes, while group 2 comprised 87 eyes of 51 patients who received continuous light A-CXL (cl-CXL) at a power of 12 mW/cm2 with an irradiation time of 10 minutes. Recordings of the central and peripheral demarcation line depths (DD), and the maximum (DDmax) and minimum (DDmin) DD, using anterior segment optical coherence tomography, were compared between the two studied groups one month after the treatment protocol. Treatment stability was also evaluated pre and postoperatively (one year following surgery) by comparing the refractive and keratometric outcomes in both groups. The differences between the preoperative corneal thickness (minimum and central) and the epithelial thickness measurements between both groups were not statistically significant. Although group 1 had slightly larger central DD (223.4 ± 62.3 um), DDmax (240.4 ± 61.8 um), and DDmin (201 ± 54 um) than those of group 2 (221.8 ± 37 um, 229.1 ± 38.4 um, and 212 ± 37.2 um, respectively), the differences between both groups' measurements were not statistically significant. Also, the two groups showed statistically insignificant differences regarding the subjective refraction and the average and maximum keratometry pre and postoperatively, denoting visual, refractive, and keratometric stability in both groups. Longer duration cl-CXL seems to be as effective as pl-CXL regarding both postoperative stability and the extent of corneal tissue penetration by the ultraviolet treatment.

CSAST: Content self-supervised and style contrastive learning for arbitrary style transfer

Arbitrary artistic style transfer has achieved great success with deep neural networks, but it is still difficult for existing methods to tackle the dilemma of content preservation and style translation due to the inherent content-and-style conflict. In this paper, we introduce content self-supervised learning and style contrastive learning to arbitrary style transfer for improved content preservation and style translation, respectively. The former one is based on the assumption that stylization of a geometrically transformed image is perceptually similar to applying the same transformation to the stylized result of the original image. This content self-supervised constraint noticeably improves content consistency before and after style translation, and contributes to reducing noises and artifacts as well. Furthermore, it is especially suitable to video style transfer, due to its ability to promote inter-frame continuity, which is of crucial importance to visual stability of video sequences. For the latter one, we construct a contrastive learning that pull close style representations (Gram matrices) of the same style and push away that of different styles. This brings more accurate style translation and more appealing visual effect. A large number of qualitative and quantitative experiments demonstrate superiority of our method in improving arbitrary style transfer quality, both for images and videos.

Risk Assessment of Distracted Driving Behavior Based on Visual Stability Coefficient

Cell phone call operations during driving can lead to distraction and cause potential safety hazards. In order to quantitatively characterize the influence of cell phone call mode on the driver’s visual behavior in different traffic conditions and to analyze the risk level of distracted driving from the visual level, a distracted driving simulation test was carried out based on a driving simulator and eye tracker. The eye movement data of drivers during normal driving, hands-free call, and video call under two typical traffic conditions of free flow and congested flow on the urban expressway were collected. Firstly, four visual characteristics indicators that were highly sensitive to traffic conditions and driving states were selected in terms of visual field range, visual recognition, visual search, and visual load, which were the information entropy of fixation area (IEFA), saccade amplitude, peak-to-average ratio of saccade velocity (PARSV), and relative change intensity of pupil area (RCPA). Then, based on the improved CRITIC method, the visual stability coefficient (VSC) was constructed as a new indicator to comprehensively assess the risk level of the driving state, and the assessment criteria were divided. Finally, the grey correlation analysis method was introduced to verify the assessment effect of VSC. The results show that different cell phone call modes increased driving risk in both traffic conditions. Among them, the negative influence of video calls on driving safety was significantly higher than that of hands-free calls, with a significant decrease in VSC, and the drivers’ VSC in the free flow scenario was more sensitive to the impact of cell phone call operation, and the driving risk increased significantly during distracted driving. The VSC can quantitatively assess driving risk from the perspective of visual psychological safety and contributes to the development of corresponding early warning and control measures.

Voronoi treemap in Manhattan distance and Chebyshev distance

The ordinary Voronoi treemap generated based on the Euclidean distance function has the flexibility to slightly adjust the layout when visualizing time-varying hierarchical data for better visual quality, preserving neighborhood relationships, and preserving a stable layout. However, its layout formed by segments with arbitrary orientations has poor shape stability between successive layouts at different time indexes, which is not conducive for the users to understand the plot and track the same node. In this paper, we propose novel Voronoi treemaps in Manhattan distance and Chebyshev distance respectively, such that the segments in the new layouts only have four orientations (horizontal, vertical, and ±45° to the [Formula: see text]-axis). The new layouts can not only heritage the abilities of ordinary Voronoi treemap, but preserve good shape stability. To achieve this, we first focus on the weighted bisector between two sites in Manhattan distance and design a bisector generation method for different weight values of two sites, as the bisector is the foundation to form a diagram. Then a divide-and-conquer method is utilized to form the bisectors into a Voronoi diagram, and a Voronoi treemap layout can be finally obtained by using Lloyd’s method to iteratively adjust the diagram. Moreover, we prove that the treemap algorithm in Manhattan distance can be adjusted to also generate the Voronoi treemap in Chebyshev distance via linear transformation, avoiding designing additional algorithm. The computational properties of the proposed methods are first evaluated to check whether the layouts can be generated fast and accurately. Then the perceptual properties are evaluated quantitatively and qualitatively based on quality metrics and user studies, respectively. The results demonstrate that the proposed Voronoi treemaps preserve similar layout stability, but better visual quality and shape stability than the ordinary Voronoi treemap. Our algorithms are simple and resolution-independent, but also provide alternatives to the Voronoi treemaps.

Physicochemical investigations on the interaction of an anionic surfactant with cellulose based polymer microgel

Abstract This work focuses on the interaction of cellulose-based colloidal microgel dispersions with the anionic surfactant sodium dodecyl sulfate (SDS) at different concentrations. First, a Cellulose-P(NIPAAm-MAA)-based responsive microgel sample was prepared by a radical polymerization method using a one-pot process. The samples thus obtained were purified, characterized and used to study microgel-surfactant interactions. To this end, SDS solutions with different concentrations were prepared and the interactions of SDS in the premicellar and micelle regions with polymer microgel were investigated using different physicochemical techniques. Experiments were also performed at different temperatures to obtain the degree of binding of SDS to microgel in gel surfactant mixtures. Due to the temperature-sensitive properties of microgel, we observed significant changes in various properties of microgel-surfactant mixtures when the solution temperature changed. The overall results showed that various experimental variables, such as the polymer gel/surfactant ratio and temperature, affect the gel–surfactant interaction quantitatively and qualitatively. With increasing surfactant concentration, conductance, viscosity and absorbance values ​​increased, but a decrease in surface tension was observed. This is due to the adsorption of SDS at the air-water interface. The micellar activity of surfactants is enhanced by the addition of microgels. It was found that the strength and nature of the interaction depended not only on the gel/surfactant ratio, solvent type and test temperature, but also on the chemical structure of the surfactant used. Furthermore, the visual stability of the colloidal particles in the mixture of microgel and SDS was also noticeable over time.

A rapid extraction process monitoring of Swertia mussotii Franch. With near infrared spectroscopy

Swertia mussotii Franch. (SMF), a traditional Tibetan medicine, which has miraculous effect on treating hepatitis diseases. However, there is no research on its entire production process, and invisible production process has seriously hindered the SMF modern development. In this study, principal component analysis (PCA), subtractive spectroscopy, and two-dimensional correlation spectroscopy (2D-COS) were used to explain changes of characteristic groups in the extraction process. Four main characteristic peaks at 1884 nm, 1944 nm, 2246 nm and 2308 nm were identified to describe the changes of molecular structure information of total active components in SMF extraction process. In addition, multi critical quality attributes (CQAs) models were established by near-infrared spectroscopy (NIRS) combined with the total quantum statistical moment (TQSM). The coefficients of determination (R2eval and R2ival) were both greater than 0.99. The ratios of the standard deviation of validation to the standard error of the prediction (RPDe and RPDi) were greater than five. The quantitative model of AUCT could save time on primary data measurement by not requiring determination of indicator components compared with others. In conclusion, these results demonstrated that it was feasible to understand the SMF extraction process through AUCT and characteristic groups. These could realize the visual digital characterization and quality stability of the SMF extraction process.

Molecular and Functional Changes to Postsynaptic Cholinergic Signaling in the Vestibular Sensory Organs of Aging C57BL/6Mice.

Cholinergic circuits in the central nervous system are vulnerable to age-related functional decline, but it is not known if aging impacts cholinergic signaling in the vestibular sensory organs, which are critically important to balance maintenance and visual gaze stability. We have previously shown cholinergic neurotransmission between vestibular efferent terminals and type II mechanosensory hair cells requires the alpha9 (Chrna9) nicotinic receptor subunit. Homozygous knockout of the alpha9 subunit causes vestibulo-ocular reflex adaptation deficits that mirror those observed in aged mice. This prompted examination of cholinergic signaling in the vestibular sensory organs of aged mice. We confirmed older (>24months) mice had impaired performance in a balance beam task compared to young (3-4months) adult mice. While there was no qualitative loss of cholinergic axon varicosities in the crista ampullaris of old mice, qPCR analysis revealed reduced expression of nicotinic receptor subunit genes Chrna1, Chrna9, and Chrna10 in the cristae of old relative to young mice. Functionally, single-cell patch clamp recordings taken from type II vestibular hair cells exposed to acetylcholine show reduced conductance through alpha9/10 subunit-containing nicotinic receptors in older mice, despite preserved passive membrane properties and voltage-activated conductances. These findings suggest that cholinergic signaling in the peripheral vestibular sensory organs is vulnerable to aging processes, manifesting in dynamic molecular and functional age-related changes. Given the importance of these organs to our everyday activities, and the dramatic increase in fall incidence in the older, further investigation into the mechanisms of altered peripheral vestibular function in older humans is warranted.

Early Impact of Laser Vision Correction (LVC) on the Stability and Quality of the Retinal Image

This retrospective comparative study analyzes the early postoperative impact of laser vision correction for myopia on the optical quality and stability of functional vision using a double-pass aberrometer. Retinal image quality and visual function stability were assessed preoperatively, one and three months after myopic laser in situ keratomileuses (LASIK) and photorefractive keratectomy (PRK) using double-pass aberrometry (HD Analyzer, Visiometrics S.L, Terrassa, Spain). The parameters analyzed included vision break-up time (VBUT), objective scattering index (OSI), modulation transfer function (MTF), and Strehl ratio (SR). The study included 141 eyes of 141 patients, of whom 89 underwent PRK and 52 underwent LASIK. No statistically significant differences were noted between the two techniques in any analyzed parameters at three months postoperatively. However, a significant drop was observed in all parameters one month after PRK. Only the OSI and VBUT remained significantly altered from baseline at the three months follow-up visit, with an increased OSI by 0.14 +/- 0.36 (p < 0.01) and a shortened VBUT by 0.57 +/- 2.3 s (p < 0.01). No correlation was found between the changes in optical and visual quality parameters and age, ablation depth, or postoperative spherical equivalent. The stability and quality of the retinal images were similar between LASIK and PRK at three months postoperatively. However, significant degradation in all parameters was found one month after PRK.

Rheological behaviour, hydration, and microstructure of self-compacting concrete incorporating ground ferronickel slag as partial cement replacement

Self-compacting concrete (SCC) is a special type of concrete which has some additional requirements beyond those of traditionally vibrated concrete, such as high flowability and consolidation by self-weight without any segregation of the ingredients. In this research, the production of SCC has been investigated by utilizing a metallurgical by-product, namely ferronickel slag (FNS) to enhance the green supply chain in concrete industry. FNS at 40% replacement of natural sand, and ground ferronickel slag (GFNS) at the rates of 0%, 20%, 35%, and 50% replacement of cement was used, and the rheological, hydration, strength, and microstructural development of SCC are presented in this paper. The fresh properties were assessed by rheology, slump flow, T50, V-funnel, J ring, L-box, U-box, and visual stability index tests. The heat of hydration was determined by isothermal calorimetry, and scanning electron microscope, energy dispersive x-ray spectroscopy, and x-ray powder diffraction techniques were used for microstructural analysis. The results were evaluated against the recommendations of the European and Japanese standards for SCC. Increases in fluidity and workability and decreases in yield stress and viscosity were observed with the increase in GFNS content. Delayed hydration heat was observed with the use of GFNS. The low calcium content of GFNS is attributed to this retardation. The 28 days compressive strength decreased from 79 MPa for the control mix by 16% due to 35% cement replacement by GFNS. This is considered reasonable due to the use of low-calcium GFNS as a cement replacement. The heterogeneous and porous morphology of the microstructure of GFNS incorporated SCC is ascribed to this decrement. Considering both fresh and hardened properties, the GFNS incorporated SCC mixtures are found comparable to the control SCC mixture. Therefore, FNS can be used as a promising alternative ingredient for SCC to strengthen the eco-friendly supply chain and sustainable waste management.

Development of Eco-friendly Self-compacting Concrete Using Fly Ash and Waste Polyethylene Terephthalate Bottle Fiber

This study aims to utilize fly ash and waste PET bottles for producing more sustainable self-compacting concrete (SCC) with better mechanical strength. Fly ash is utilized as a supplementary cement material and waste PET bottles as fiber reinforcement to improve its flexural strength and achieve the targeted compressive strength. The experimental works were conducted on eight variations using 80 specimens, divided into two main groups of partial cement replacement using 0% and 15% fly ash by weight. The two variants are added with PET fiber based on the volume fractions of 0%, 0.25%, 0.50%, and 0.75%. Fresh concrete was tested using the slump flow method (T50) and the Visual Stability Index (VSI) based on ASTM 1611. The hardened concrete tests are conducted after 56 days and include testing the concrete's compressive strength, flexural strength, and ultrasonic pulse velocity. Test results showed that the presence of PET fiber in the SCC mix decreased its flowability. However, when added up to 0.75%, the mixes still meet the flowability requirements of fresh-state SCC. PET fiber addition tends to reduce the compressive strength, whereas the reduction in compressive strength of SCC with PET fiber without fly ash is insignificant. However, in SCC that uses fly ash, the addition of PET fiber causes a significant decrease in its compressive strength. Adding PET fiber into SCC mixes can increase flexural strength, both for the two variants: SCC without fly ash and SCC with fly ash. It can be concluded that PET waste fiber with an aspect ratio of 40 can be added up to 0.5% for SCC without fly ash and up to 0.25% by volume fraction for SCC with fly ash addition. The ultrasonic pulse velocity test results have an excellent tendency to predict the concrete's compressive and flexural strengths. Therefore, the UPV test can be applied for the non-destructive test evaluation of PET fiber-reinforced SCC. Doi: 10.28991/CEJ-2023-09-02-014 Full Text: PDF

Long-term Safety and Efficacy of Corneal Collagen Crosslinking in a Pediatric Group With Progressive Keratoconus: A 7-year Follow-up

To assess effectiveness and safety of corneal crosslinking (CXL) to reduce keratoconus (KC) progression and improve visual acuity among children with progressive KC and to analyze the use of 20% dextran-based (Dextran) and 1% hydroxypropyl methylcellulose-based (HPMC) riboflavin. Prospective, clinical cohort study METHODS: Standard CXL (SCXL) was performed in 74 eyes (58 patients, 45 males, mean age 13.0 ± 2.1 years): 53 eyes with HPMC and 21 with Dextran. Examinations were performed at baseline, 3 and 6 months, and 1, 2, 3, 4, 5, and 7 years of follow-up, including uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), a complete ophthalmologic examination, anterior segment ocular coherence tomography, Scheimpflug corneal tomography, and specular microscopy. UDVA and CDVA improved at all periods with statistically significant differences in CDVA at 1, 2, and 3 years. Compared with baseline, maximum K (Max K) reduced throughout the 7-year follow-up. Mean thinnest pachymetry (Th Pachy) decreased significantly at 3 months and remained low; in the Dextran group, the Th Pachy mean value returned to baseline 6 months postoperatively. After CXL, 1.5 diopter progression in max K was 1.4% to 14.6% of eyes; worsening was found at 4 to 7 years postoperatively. SCXL reduced KC progression in children up to 7 years of follow-up and revealed improvement and stability of UDVA and CDVA in 82% of eyes. For visual acuity and KC stability, no statistically significant difference was observed between Dextran-HPMC. The HPMC group showed persistent cornea thinning, raising concerns about its use in SCXL.