Reseda luteola is a plant species in the genus Reseda. The common name is weld. The plant is rich in luteolin, a flavonoid that produces a bright yellow dye. This dye is more important and noticeable than other natural yellow dyes due to its high transparency and color strength, and better general fastness. Cellulose and waste tissue in natural dyes reduce the efficiency and quality of natural dyeing, occupy a large volume of dyeing equipment with dye plant pulp and complex dye matching. To make maximum use of the dye in the plant, applying the extraction methods is inevitable. Much research has been done in the field of dye extraction from this plant. Extraction of natural dyes from weld with the help of traditional methods such as boiling, soaking and steaming and modern techniques such as Soxhlet, microwave, ultrasound, plasma, membrane, critical liquid and the effect of various solvents such as water, methanol, ethanol, water-ethanol, and water Methanol as well as auxiliaries during dyeing and extraction have been considered by researchers. The results show the effectiveness of some extraction methods compared to the conventional method, different solvents, and the effects of extraction bath pH. The results of dye extraction from weld using filtration methods and wool dyeing led to the superiority of deposition of dyes by alum mordant and then ultrafiltration. Compared to Soxhlet extraction methods with the ultrasonic technique, extraction efficiency was superior and less time and energy was spent in the ultrasound method showed excellent extraction efficiency. In general, research has been demonstrated that dye powder extracted from weld can be used instead of the plant. In addition, use in the pharmaceutical and health industries increases the efficiency and quality of dyeing and can be an excellent alternative to synthetic dyes. In this study, the researches related to different dye extraction methods from the weld, the effect of solvents and auxiliaries on the extraction efficiency, and dyeing quality are reviewed and introduced.

Use of an adhesive with a suitable composite resin is an important factor in tooth-colored restorations and increasing marginal sealing ability. The aim of this study was to evaluate the microleakage of various adhesives with composite resins using fluid filtration and dye extraction techniques and assessment of the correlation between these two techniques. In this in vitro study, class II cavities were prepared on the proximal surfaces of 48 extracted sound human premolar teeth, measuring 1.5±0.5 mm in gingival width, 4 mm in occluso-gingival height and 1/3 of the inter-cuspal distance in width. The samples were divided into four groups (n=12). Group 1; OptiBond Solo Plus adhesive/Herculite XRV composite resin; Group 2: OptiBond Solo Plus adhesive/Master Dent composite resin; Group 3: Prime & Bond NT adhesive/Herculite XRV composite resin; Group 4: Prime & Bond NT adhesive/Master Dent composite resin. Microleakage was assessed primarily by fluid filtration and then by dye extraction techniques. Data were analyzed with Kruskal-Wallis and Mann-Whitney tests, with Bonferroni correction and Spearman's rho correlation test at 95% confidence interval. The minimum and maximum mean microleakage values were recorded in fluid filtration and dye extraction techniques groups 1 and 4, respectively. There were significant differences between the experimental groups in microleakage with the two methods of leakage assessment (p value = 0.001). Spearman's rho revealed a strongly direct correlation between the two methods (r = 0.797, p value = 0.000). In both methods of microleakage assessment, use of ethanol-based in comparison to acetone-based adhesive resulted in microleakage reduction. Application of light-cured composite resin contrary to self-cured composite resin with both types of adhesives increased marginal sealing ability.

In the past few decades, there is increasing trend to use products from natural resources. Dyes obtained from natural sources are among such products. The present research mainly focuses on optimization of extraction conditions during a natural dye extraction from the flower petals of a tree ‘Flame of Forest’. Taguchi technique was employed for optimization of the parameters namely raw dyestuff particle size, solid-liquid ratio, time of extraction and method of extraction assistance. The results indicated that 150 micron particle size, 1:20 solid-solvent ratio, two hours for extraction and enzyme addition as assistance for extraction were the optimum conditions for extraction. The optimum and control extractions were compared for their absorbance values and the subsequent dye yields. The respective absorbance values were 1.144 and 1.036. It was encouraging to observe 10.58 yield increment in the extraction with optimized parameters.

Annatto color is one of the oldest of natural carotenoids that have wide applications in food technology. Annatto color is the second natural color additives used in world industry, of economic. It is predicted that demand for it is increasing day by day. Color extraction from annatto seed is done by conventional methods, mainly. Little information is available about the use of new techniques such as response surface methodology of ultrasound technology in the extraction of annatto color. The subject of this study was to optimize the ultrasound-assistant extraction process of annatto color and determination of the best process conditions by using response surface methodology and central square design. The central composite design was used in order to evaluate the effect of extraction temperature (80-20 °C), extraction time (10-2 min), seed to solvent ratio (5-20 %) and duty cycle (0.2-0.8 s), on efficiency of dye extraction from annatto seed and to optimize the extraction process. ANOVA shows the seed to solvent ratio variable (X4) and it square effect (X42) have the greatest impact on dye extraction from the annatto seeds. In temperature of 72.7 °C, extraction time of 7.25 min, the seed to solvent ratio of 14 percent and duty cycle of 0.8 s were found as the optimum conditions of the ultrasound-assistant extraction process in order to obtain the maximum efficiency of color under which the absorbance value and extraction efficiency was determined as 0.865 and 6.35 percent of annatto seed, respectively.

Nowadays، Dye sensitized solar cells (DSSCs) emerged as a new class of low cost solar cells that affordable to convert light energy into electrical energy and also they are known as the third generation of solar cells founded on nano structured thin films. Titanium dioxide usually plays as the semiconductor for transmission of excited electrons from dye to the counter electrode (cathode). During one cycle of electron transfer، which electrolyte plays an important role in the electron transportation، electrons will return to the excited dye molecules. This phenomenon practically presents the sunlight conversion into electricity by solar cells. In this project eggplant was used as a natural source of dye for fabrication of DSSC. Dye extraction was performed by suitable solvent and its purification was conducted by Solid Phase Extraction columns. The electrochemical evaluation and final efficiency measurement of fabricated cells were carried out by Electrochemical Impedance Spectroscopy method which is well known as a powerful and non destructive technique in studying of charge transfer on the surface of nano structured electrodes.

Dyes are one of the most widely used components in different industries. Recently much attention has been focused on the replacement of natural pigments instead of synthetic colors. One of the most important sources for the production of natural pigments are medicinal plants that small number of them used as industrial and some of them are traditionally used. The worldwide demand for natural dyes increases nowadays due to environmental and echo friendly of them. Many of the plants used for dye extraction are classified as medicinal and some of these have recently been shown to possess remarkable antimicrobial and antiinflamtory activities. The present review describes important information about dye-yelding herbs and their medicinal properties.

The dye extracted from the plant is already well used in optoelectronic applications for its easy and safe handling. This study is to demonstrate the effect of magnetized distilled water on dye extracted from Anchusa-Italica flowers. The results of its optoelectronic behavior reveal that the use of magnetized water in the extraction process results in different and better properties than processes in which ordinary water was used. The structural analysis of Anchusa-Italica dye thin-film was performed using the Fourier-transform infrared technique (FT-IR). The optical responses, such as the absorption coefficient, absorption spectra, both standard and refractive indices, and electronic properties (optical energy gap) were studied using Ultraviolet-Visible transmittance spectra range 300–900 nm. The calculated energy band gap of the dye extracted using magnetized water was decreased from 3.23 to 2.35 eV and turned into the preferred direct band gap to make a useful contribution to optical sources. The optical absorption spectra of the dye extracted using magnetized water appear to have a better efficiency compared to that extracted with ordinary water. A significant evolution in the absorption coefficient was obtained by employing magnetized water to extract the dye. The magnetized extraction process also modified the electronic transmission values (indirect to direct). The effect of magnetized water on the resonance mode and transparent indication was deduced by studying the complex refractive index. An increase appeared in the spectrum of the absorption index at a wavelength of 570 nm, whereas a small attenuation coefficient was observed as well. The important effects of magnetized dye extraction will highly benefit the field of optoelectronic applications.

The research on dye solubility modeling in supercritical carbon dioxide is gaining prominence over the past few decades. A simple and ubiquitous model that is capable of accurately predicting the solubility in supercritical carbon dioxide would be invaluable for industrial and research applications. In this study, we present such a model for predicting dye solubility in supercritical carbon dioxide with ethanol as the co-solvent for a qualitatively diverse sample of eight dyes. A feed forward back propagation - artificial neural network model based on Levenberg-Marquardt algorithm was constructed with seven input parameters for solubility prediction, the network architecture was optimized to be [7-7-1] with mean absolute error, mean square error, root mean square error and Nash-Sutcliffe coefficient to be 0.026, 0.0016, 0.04 and 0.9588 respectively. Further, Pearson-product moment correlation analysis was performed to assess the relative importance of the parameters considered in the ANN model. A total of twelve prevalent semiempirical equations were also studied to analyze their efficiency in correlating to the solubility of the prepared sample. Mendez-Teja model was found to be relatively efficient with root mean square error and mean absolute error to be 0.094 and 0.0088 respectively. Furthermore, Grey relational analysis was performed and the optimum regime of temperature and pressure were identified with dye solubility as the higher the better performance characteristic. Finally, the dye specific crossover ranges were identified by analysis of isotherms and a strategy for class specific selective dye extraction using supercritical CO2 extraction process is proposed.

Food consumers tend to use natural products without any synthetic additives. Therefore, many studies have been conducted to investigate the possibility of replacing synthetic additives with natural substances in various food products.
Annatto dye is a natural carotenoid pigment extracted from the pericarp of BixaorellanaL. seeds. The major fraction of the annatto extract is 9´-cis-bixin that is soluble in oil and 9´-cis-norbixin is the major dye fraction of the alkaline extract that is soluble in water. Annatto dye creates orange to red color in food and to be used as a natural pigment in a variety of food materials including cheese, butter, margarine, confectionary and bakery products, different kinds of drinks, snacks and jams. In addition, annatto dye has antioxidant and antimicrobial activity.
Nowadays, the extraction of natural dye from plant resources has become a common technology. However, complementary information using new methods and optimization of the extraction conditions seems to be necessary in order to accomplish the highest yield of extraction. Response surface method (RSM) is effective and efficient in optimizing color extraction conditions.
In this study, the different conditions of extraction process were optimized through RSM in order to obtain maximum yield and best quality of annatto dye.
Materials Annatto seeds were purchased from Hyderabad, India. All solvents were analytical grade, Merck, Germany.
Extraction of annatto dye
A certain amount of annatto seeds was soaked in n-hexane for 6 hours in order to remove oils. After filtration, the defatted seeds were used for dye extraction. Since chloroform and acetone showed the highest yields of extraction during preliminary experiments, these two solvents and their mixtures were exploited for the final experiments assigning 0 for pure acetone and 100 for pure chloroform. The extracts were filtered through Whatman filter paper NO.1 and then vacuum-dried in the 1410D-2E vacuum oven (Shel Lab, USA) to produce dye powder. Low temperatures (40°C) were applied to prevent thermal dissociation of conjugated double bonds during drying.
Dye measurement
The coloring strength was measured according to Vasu et al. method; model UV-160A spectrophotometer Shimadzu, Japan, at 502 nm in which bixin has the maximum absorbance value when it is dissolved in chloroform.
Determination of extraction efficiency
The obtained powder was weighed and the mass ratio of the powder to the weight of the seeds was taken into account as the extraction yield.
Experimental design
In this study, Minitab® software version 16.1.1 (Minitab Inc. USA. 2010), was used and a five level four factor central composition design was created to investigate the effect of the independent variables such as temperature, extraction time, seed to solvent ratio and chloroform concentration on the dependent variables namely the extraction efficiency and absorbance values.
The values of R2, R2-adj and R2-pred revealed that the full quadratic models were the most adequate for the extraction efficiency and absorbance values.
The all of the linear terms show a significant effect except the extraction time (P 0.05). The interactive terms of extraction temperature* seed to solvent ratio(X1X3) and the seed to solvent ratio*Chloroform concentration (X3X4) had a significant effect on the extraction efficiency (P 0.05).For the absorbance values, the all of the linear terms show a significant effect (P 0.05). The all of interactive terms was insignificant (P> 0.05).
An increase in the extraction efficiency was observed with the increasing temperature. Banik and Pandey while extracting oleanolic acid from Lantana camararoots demonstrated that as temperature increases extraction efficiency improves too. However, at temperatures higher than 70 °C, the annatto seed pigments were degraded and the response was reduced so the quadratic effect of temperature was negative.
The absorbance value was increased by increasing the temperature; however, the absorbance value decreased at higher temperature by thermal decomposition and damage of the conjugate double bond.The absorbance value increased by increasing the chloroform concentration and seed to solvent ratio initially, however, subsequently decreased due to the damage of the conjugate double bond in higher chloroform concentration and saturation of solvent in higher seed to solvent ratio.
Temperature of 48.33 ˚C, extraction time of 2 hr, the ratio of seed to the solvent of 12.88 and chloroform concentration of 100% were found to be as the optimum conditions of the process. The extraction efficiency of 3.95 percent of annatto seed and absorbance value of 0.597 were acquired as the predicted results.

This study presents the natural dye recovery from various biodegradable temple and household wastes. The raw material for colour extraction consisted residual flowers and garlands from various temples as well as onion and vegetables peels from vegetable markets, university hostels, and households, which were washed, dried, crushed, and sieved. The extracted natural colours were produced by means of ultra-sonication, and were dried in the spray drier, being characterized by FT-IR and UV-Vis Spectrophotometers. They were used to dye various fabrics such as cotton, silk, and wool, not to mention different mordents. It was found out that the remaining residue, left after dye extraction, was rich in nutrients, hence, it could be further used as the resource material, itself. As a result, we explored these residual wastes for vermicomposting and biochar production, which can be further employed as an organic fertilizer for agriculture. Overall, the present waste management approach will lead to a closed-loop environmental management through waste reduction and reutilization. It will also provide value-added materials for economic gains from waste. Thus, it can be promoted as a potential mechanism to maintain the environmental sustainability at wider scales.