Binocular Function in Different Gaze Positions.

Purpose: To evaluate varied aspects of binocular function in multiple gaze positions. Methods: In 2018, this cross-sectional study was conducted on 21 participants (male = 11) with an age range of 19-25 years. Having emmetropia and 10/10 visual acuity in both eyes were conditions of the inclusion criteria for the cross-sectional study. The following aspects of binocular function including amplitude of accommodation (AA), near point of convergence, near phoria, and monocular accommodative facility were evaluated in five gazes (primary, upward, downward, left, and right) for all subjects. Results: Near point of convergence values showed significant differences in all gaze positions (P < 0.001). The lowest near point of convergence value was seen in the primary gaze (2.69 cm) and the downward gaze (3.47 cm) and the highest near point of convergence value was seen in the left gaze (7.5 cm). There was also a significant difference in the amplitude of accommodation among the upward, downward, and the primary gaze (P < 0.001) positions but no difference was observed among the temporal, nasal, and the primary gaze positions. There was a significant difference in near phoria between the upward gaze and the primary gaze (P = 0.008) while no significant differences were observed among the other gazes. There was no significant variance in the monocular accommodative facility among the different gaze positions (P = 0.175). Conclusion: The results of this study indicated variations that exist in the convergence and accommodation reflex functions in multiple gaze positions, which proved to be more prominent in the convergence system. Although the accommodative sufficiency evaluation was inconsistent among the multiple gaze positions, the accommodative facility evaluation was consistent in all gazes.

Gum tragacanth dispersions: Particle size and rheological properties affected by high-shear homogenization.

The effect of high-shear homogenization on the rheological and particle size characteristics of three species of gum tragacanth (GT) was detected. Dispersions were subjected to 0-20 min treatment. Static light scattering techniques and rheological tests were used to study the effect of treatment. The results showed that the process caused a decrease in particle size parameters for all three species, but interestingly, the apparent viscosities increased. The highest increase of apparent viscosity was found for solutions containing Astragalus gossypinus, which possessed the highest insoluble fraction. The viscoelastic behaviors of dispersions were also significantly influenced by the process. Homogenization caused an increase in both G' and G″, in all three species. The alterations seem to be highly dependent on GT species and structure. The results could be of high importance in the industry, since the process will lead to textural modifications of food products containing GT.

A comparative study on the emulsifying properties of various species of gum tragacanth.

Emulsification activities of three different species of gum tragacanth containing Astragalus gossypinus, A. compactus and A. rahensis were investigated. Emulsion stability indexes, particle size distributions, steady and unsteady rheological properties and some other physicochemical attributes including the surface tensions and uronic acid contents were taken into consideration. It was revealed that A. gossypinus created the most stable emulsions although having lower viscosity than A. compactus. It is believed that higher insoluble fraction and higher uronic content made this species a good steric and electrostatic emulsifier.

Applying Iranian Gum Tragacanth to Improve Textural Properties of Maltodextrin Microcapsules.

The effects of adding one of the species of Iranian gum tragacanth, Astragalus compactus, to maltodextrin solutions used for microencapsulation of 2-methylbutyl acetate (water-soluble flavoring compound of strawberry) were studied. Initial emulsions were evaluated regarding rheological behavior and particle size distribution. The resulted microcapsules were also analyzed for particle size distributions, glass transition temperature Tg , the morphology of the capsules and the rate of release from them. The results showed that addition of 0.5% w/w A. compactus gum to maltodextrin solutions (14.5% w/w) can increase the viscosity and Tg to an optimum level and can prevent stickiness. Also this species of gum tragacanth had an interesting effect in reducing physical defects of microcapsules and eliminated ruptures significantly. It was also showed that the rate of release of 2-methylbutyl acetate decreased by incorporating gum tragacanth in the wall material. PRACTICAL APPLICATIONS: Microencapsulation is of great interest in preservation of flavoring compounds. One of the most important wall materials is maltodextrin, which has several defects to protect flavorings. This study proposes the use of a new material, Iranian gum tragacanth from Astragalus compactus, to overcome these defects. It was found that new microcapsules did not undergo rupture and could retain the flavoring well.