Laccase-catalyzed enzymatic dyeing of cotton fabrics

As some synthetic dyes are regarded to be toxic, mutagenic and carcinogenic, the search for eco-friendly alternatives for the synthesis of dyes and coloration has gained importance. For this reason, this study focused on finding new eco-friendly alternatives for coloring cotton. 100% cotton knitted fabrics were subjected to enzymatic coloration using a commercial laccase enzyme and various precursors. After determining the colors, the effect of pH on the enzymatic dyeing process was investigated. Then the optimization of reaction conditions was also realized statistically for the precursors giving the best results in terms of color. With the aim of obtaining further improvements in color-yield values obtained in enzymatic dyeings, the effect of the pretreatment process and the use of ultrasound were also investigated. Furthermore, the reaction pathways in enzymatic coloration were explained and results were confirmed by means of Fourier Transformed Infrared analysis. As a result of experimental studies, red and lilac colors could be successfully obtained on cotton for the first time in the literature. In this way, the theoretical basis of enzymatic dye synthesis and dyeing of cotton was clarified comprehensively. Furthermore, technical (color reproducibility; washing, rubbing, light and perspiration-fastness values; and UV protection factor), economical (chemical, energy and water consumption required for dyeing (including aftertreatments) of 1 kg fabric) and ecological aspects of enzymatic dyeings were compared with reactive dyeing. According to the experimental results it was found that biological treatment alone was enough for wastewater of enzymatic coloring, while chemical treatment will also be needed in reactive dyeing wastewater. Furthermore, color reproducibility, evenness and UV protection properties of dyed samples were comparable with that of reactive dyeings. However, in terms of the fastness levels achieved, the enzymatic coloring was far behind the reactive dyeing.

Non-Contact Dermatoscope with Ultra-Bright Light Source and Liquid Lens-Based Autofocus Function

Dermatoscopes are routinely used in skin cancer screening but are rarely employed for the diagnosis of other skin conditions. Broader application is promising from a diagnostic point of view as biopsies for differential diagnosis may be avoided but it requires non-contact devices allowing a comparably large field of view that are not commercially available today. Autofocus and color reproducibility are specific challenges for the development of dermatoscopy for application beyond cancer screening. We present a prototype for such a system including solutions for autofocus and color reproducibility independent of ambient lighting. System performance includes sufficiently high feature resolution of up to 30 µm and feature size scaling fulfilling the requirements to apply the device in regular skin cancer screening.

Optimization of Digital Transfer Textile Printing Process using Multi-Objective Function Analysis

Digital textile printing (DTP) is widely used because it is more efficient and simpler than conventional textile printing methods. Digital transfer textile printing (DTTP) is one of the most efficient and simplest DTP methods. In this study, the optimum process conditions for DTTP have been investigated, to minimize the distortion of printed images and maximize the color reproducibility. First, a novel measurement method for fabric shrinkage and image distortion was developed. Then 9 characteristic values were defined and a series of experiments were designed and performed using the Taguchi method. Finally, two different multiple-characteristic value analyses were performed on the results. In one method, 9 characteristic values were converted into a single value. In the other method, the characteristic values were divided into 3 groups for analysis. Finally, results from the two methods were compared to determine which method was more suitable.

Recycling of chromium wastes from the tanning industry to produce ceramic nanopigments

Growth in the use of colored ceramics and the demand for better quality have stimulated research into the development of new classes of pigments with superior durability and color reproducibility, which can be produced using inexpensive, straightforward, and eco-friendly synthesis procedures.