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Everyone is extremely concerned about environmental protection and health safety due to the rise in living standards. Plant-derived natural dyes have garnered much industrial attention in food, pharmaceutical, textile, cosmetics, etc. owing to their health and environmental benefits. The present study aims to focus on the elimination of the use of synthetic dyes and provides brief information about natural dyes, their sources, extraction procedures with characterization and various advantages and disadvantages.

In producing natural colors, extraction and purification are essential steps. Various conventional methods used till date have a low yield, as these consume a lot of solvent volume, time, labor and energy or may destroy the coloring behavior of the actual molecules. The establishment of proper characterization and certification protocols for natural dyes would improve the yielding of natural dyes and benefit both producers and users.

However, scientists have found modern extraction methods to obtain maximum color yield. They are also modifying the fabric surface to appraise its uptake behavior of color. Various extraction techniques such as solvent, aqueous, enzymatic and fermentation and extraction with microwave or ultrasonic energy, supercritical fluid extraction and alkaline or acid extraction are currently available for these natural dyes and are summarized in the present review article.

If natural dye availability can be increased by the different extraction measures and the cost of purified dyes can be brought down with a proper certification mechanism, there is a wide scope for the adoption of these dyes by small-scale dyeing units.

This study aims to investigate the usability of a public university website for measuring its efficiency, users’ satisfaction or anxiety while searching for and retrieving information through different devices.

A task-based approach was adopted for the study. Twenty-eight participants were asked to complete 11 information-searching tasks on the website. The participants were divided into two groups. The tasks were carried out by members of each group, using desktop and mobile devices in a rotating fashion. Volunteers observed the participants' actions and recorded information regarding their productivity, time usage (using a timer), satisfaction or annoyance while performing each task. Finally, based on the use of the devices, a comparison was established between the participants' performance accuracy, efficiency and anxiety.

The study provides an overview of a task-based user experience carried out on the university website using a combination of qualitative and quantitative research methods. According to the results, participants' satisfaction levels were generally high, and their anxiety levels were low while completing the tasks on a mobile device. In comparison to the desktop, it took less time overall to complete all tasks. On the other hand, using a desktop computer (97.1%) resulted in better task completion success rates for participants than using a mobile device (85.7%).

No previous task-based evaluation study of this kind has been conducted to assess the usability of any university website in Bangladesh.