Effect of biological shells aggregate on the mechanical properties and sustainability of concrete.

The recycling bio-waste shells problem has grown more and more serious in recent years and many efforts have been made to solve this problem. One possible solution is to put these bio-shells into concrete and recycle them as building materials using the aggregate matrix concrete approach. To verify the engineering feasibility, the mechanical properties of bio-shells aggregated concrete were invested via gradient substitution rates at 10%, 30%, and 50% with a total of 78 groups of specimens in this paper. Our results show that the mechanical properties of the concrete were enhanced in maximum flexural strength and maximum compressive. Economic performance was also analyzed and found that the costs of frame-shear structure, frame structure, and tube-in-tube structure were reduced by 10.2%, 10%, and 10.3%. The carbon environmental assessment also shows superiority in the carbon reduction of a single specimen with various rates of the shell. In summary, compared with ordinary concrete materials, it is very possible to use waste bio-shells as a substitute for aggregates to develop the sustainable recycling development of concrete materials.

MNREAD Reading Vision in Adults With Glaucoma Under Mesopic and Photopic Conditions.

Purpose: Despite good photopic visual acuity, glaucoma patients report difficulty performing daily activities under dim light such as reading. Here we investigated the impact of mesopic lighting conditions on reading vision of glaucoma patients. Methods: The study design included 39 patients with glaucoma and 40 healthy controls. Reading vision was assessed with MNREAD charts under mesopic (2 cd/m2) and photopic (220 cd/m2) conditions. Four reading indexes: maximum reading speed (MRS), critical print size (CPS), reading acuity (RA), and reading accessibility index (ACC) were obtained from the MNREAD test yielding a plot of reading speed versus print size. Results: Compared to photopic conditions, reading vision of both healthy controls and glaucoma patients significantly decreased under mesopic conditions (P < 0.05). For glaucoma patients (85% with mild or moderate glaucoma), MRS and ACC decreased by six words per minute and 0.1, respectively under mesopic conditions; CPS and RA increased by 0.25 and 0.18 logMAR, respectively. Moreover, under both photopic and mesopic conditions, reading vision of glaucoma patients was significantly worse than that of healthy controls, but the difference was greater under mesopic conditions (P < 0.05) even after controlling for age and visual acuity. Conclusions: Mesopic conditions make reading more challenging for both healthy controls and glaucoma patients. However, reading in dim light appears to be more burdensome for glaucoma patients. Mesopic reading tests mediated by both cone and rod photoreceptor systems likely provide a more sensitive and comprehensive assessment of a patient's reading impairment than testing under photopic conditions.

Altered Eye Movements During Reading With Simulated Central and Peripheral Visual Field Defects.

Purpose: Although foveal vision provides fine spatial information, parafoveal and peripheral vision are also known to be important for efficient reading behaviors. Here we systematically investigate how different types and sizes of visual field defects affect the way visual information is acquired via eye movements during reading. Methods: Using gaze-contingent displays, simulated scotomas were induced in 24 adults with normal or corrected-to-normal vision during a reading task. The study design included peripheral and central scotomas of varying sizes (aperture or scotoma size of 2°, 4°, 6°, 8°, and 10°) and no-scotoma conditions. Eye movements (e.g., forward/backward saccades, fixations, microsaccades) were plotted as a function of either the aperture or scotoma size, and their relationships were characterized by the best fitting model. Results: When the aperture size of the peripheral scotoma decreased below 6° (11 visible letters), there were significant decreases in saccade amplitude and velocity, as well as substantial increases in fixation duration and the number of fixations. Its dependency on the aperture size is best characterized by an exponential decay or growth function in log-linear coordinates. However, saccade amplitude and velocity, fixation duration, and forward/regressive saccades increased more or less linearly with increasing central scotoma size in log-linear coordinates. Conclusions: Our results showed differential impacts of central and peripheral vision loss on reading behaviors while lending further support for the importance of foveal and parafoveal vision in reading. These apparently deviated oculomotor behaviors may in part reflect optimal reading strategies to compensate for the loss of visual information.

Altered eye movements during reading under degraded viewing conditions: Background luminance, text blur, and text contrast.

Degraded viewing conditions caused by either natural environments or visual disorders lead to slow reading. Here, we systematically investigated how eye movement patterns during reading are affected by degraded viewing conditions in terms of spatial resolution, contrast, and background luminance. Using a high-speed eye tracker, binocular eye movements were obtained from 14 young normally sighted adults. Images of text passages were manipulated with varying degrees of background luminance (1.3-265 cd/m2), text blur (severe blur to no blur), or text contrast (2.6%-100%). We analyzed changes in key eye movement features, such as saccades, microsaccades, regressive saccades, fixations, and return-sweeps across different viewing conditions. No significant changes were observed for the range of tested background luminance values. However, with increasing text blur and decreasing text contrast, we observed a significant decrease in saccade amplitude and velocity, as well as a significant increase in fixation duration, number of fixations, proportion of regressive saccades, microsaccade rate, and duration of return-sweeps. Among all, saccade amplitude, fixation duration, and proportion of regressive saccades turned out to be the most significant contributors to reading speed, together accounting for 90% of variance in reading speed. Our results together showed that, when presented with degraded viewing conditions, the patterns of eye movements during reading were altered accordingly. These findings may suggest that the seemingly deviated eye movements observed in individuals with visual impairments may be in part resulting from active and optimal information acquisition strategies operated when visual sensory input becomes substantially deprived.