Accelerating effect of ethylene diaminetetraacetic acid on dichromate-indigo and dichromate-iodide reactions
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Potassium dichromate
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Subtle color difference between silk cloth dyed with traditional natural indigo and industrial synthetic indigo was studied using a spectrophotometer. Color difference between silk and cotton cloth using natural indigo was also examined. Color was analyzed by a CIELAB color system and compared. Results showed 1) color of silk cloth dyed with natural indigo was brighter than that dyed with synthetic indigo, 2) subtle difference in color of silk cloth dyed with indigo was affected by indigo concentration in the dyed cloth rather than by other coloring materials in dye, 3) color of silk cloth was brighter than that of cotton cloth using natural indigo, and 4) functional groups may have little influence on results in this study.
Color difference
Natural dye
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Indigo has a long history of medicinal use with particularity and complexity in its processing. Before the Ming dynasty,Indigo was extracted from the top layer of zymotic fluid,called purified Indigo In modern processing,the precipitate crude Indigo Naturalis is dried to produce Indigo after impurity removal. The form of Indigo slices has undergone significant changes in ancient and modern times. In view of this,the quality comparison between crude Indigo and purified Indigo was conducted in this study with modern analytical techniques. Firstly,chemical composition was analyzed with UPLC-Q-TOF-MS,and the chemical composition of scent with HS-SPME/GC-MS/MS. The content of indigo,indirubin,total ash,and water-soluble extract was determined as well as the inorganic composition in crude Indigo and purified Indigo Naturalis. Then,their microscopic morphology was observed and the surface element composition was investigated. Finally,the antipyretic activities of crude Indigo and purified Indigo were compared in the fever rat model induced by lipopolysaccharide and 2,4-dinitrophenol. The results demonstrated that the purified Indigo had a faster and more lasting antipyretic effect,while the crude Indigo had almost no antipyretic effect. This study is of great significance to the research on processing technology of Indigo and provides reference for the formulation of its quality standards,production specifications and calibration procedures.
Indirubin
Indigo carmine
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Chromium oxide nanoparticles (NPs) were rapidly synthesized by reduction of potassium dichromate solution with a Tridax procumbens leaf extract containing carbohydrates as a major component which act as reducing agent. The results indicated that watersoluble carbohydrates which have aldehyde group may cause the formation of Cr2O3 nanoparticles. The purification process of the Cr2O3 product does not require expensive methods, since a solid product is obtained from a reaction in liquid phase. The antibacterial effect of Cr2O3 nanoparticles against Escherichia coli was investigated as a model for Gram-negative bacteria. Bacteriological tests were performed in Luria–Bertani (LB) medium on solid agar plates and in liquid systems supplemented with different concentrations of nanosized Cr2O3 particles. These particles were shown to be an effective bactericide. The resulting Cr2O3 nanoparticles were characterized by XRay Diffraction (XRD), Scanning Electron Microscopy (SEM), UV-VIS absorption and Fourier-transform infrared (FTIR) spectroscopy. Keywords: Tridax procumbens, potassium dichromate solution, Cr2O3 nanoparticles, E. coli
Potassium dichromate
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Abstract An attempt was made tot prepare N,N′‐ethene indigo, the derivative of cis‐indigo in which the nitrogen atoms are joined by an ethene link. A compound was however obtained whose probable formula is that of N,N′‐ethene indigo with a molecule of water added at the double bond between the two indol nuclei. It was found impossible to split off the water from this compound without further decomposition.
Derivative (finance)
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This chapter contains sections titled: Introduction Occurrence of Indigo Synthesis of Indigo Physical Properties of Indigo Chemical Properties of Indig Halogenated Indigos Alkyl and Acyl Derivatives of Indigo Preparation of Indigoids Isoindigo and Indirubin
Indirubin
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Natural indigo sukumo has long been a specialty of Tokushima prefecture on the island of Shikoku in Japan [1]. Natural indigo once provided work for many people, but only five indigo farms remain in Tokushima. In Japan, traditional indigo dyeing is difficult because the indigo is relatively expensive and the market is dominated by cheap synthetic indigo.(중략)
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The recovery process of indigoid compounds involves enzymatic hydrolysis of indigo precursors continued by oxidation reaction to synthesize indigo pigment. The purpose of this research was to evaluate the effect of physicochemical process variables, i.e., temperature, time, and pH aeration, on indigo yield from Strobilanthes cusia leaves. Small leaf pieces were immersed in distilled water and heated at temperatures (40, 50, and 60 °C) and duration (1, 2, and 3 h). The extract was aerated at different pHs (8, 10, and 12) to form the indigo product. The indigo concentration was quantified through a visible spectrophotometer and high-performance liquid chromatography (HPLC). The optimized condition for indigo production was studied using response surface methodology (RSM). Temperature, time, and interaction between temperature and time significantly affected the indigo yield. The optimized conditions for extraction of indigo dyes were determined to be at 60 °C for 1 h and pH 8 for maximizing the indigo yield. On that condition, the indigo concentration quantified by HPLC was 1.15% (w/v) which was lower than that by the spectrophotometry. By spectrophotometric analysis, the actual indigo content of 1.68% (w/v) on that optimum condition was close to the predicted indigo content of 1.77% (w/v) using RSM.
Distilled water
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This paper is a comparative analysis of the $19^{th}$ century practice of indigo dyes and dyeing in Korea and England. From over hundreds species of indigo plants in the world, it was dyer's knotweed and woad that were cultivated in Korea; however, the only indigo plant grown in England was woad. Indigo dye was produced in the form of damp indigo sediment (jeon) in Korea; however, imported indigo (as a main dye) and couched woad (as an additional dye) were indigo dyes used in England. There existed three kinds of indigo vats, the ice vat, ash-water vat, and indigo sediment (jeon) vat, in Korea. The fresh leaves of indigo were used for both the ice vat and ash-water vat. The ice vat was very convenient for preparation, but had a weakness in the inability to produce a very deep shade of blue. The ash-water vat and indigo sediment (jeon) vat were in use for producing a very deep shade of blue. The indigo sediment Goon) vat was employed presumably only by professional dyers. The indigo vat practiced in England was categorized into two types; one was woad-indigo vat, and the other was an indigo powder vat prepared by using imported indigo rock. There was a tendency to adopt different kinds of indigo vats according to the material to be dyed. The woad-indigo vat was employed for the dyeing of wool. A few of chemical vats with imported indigo were adopted, especially for the dyeing of cotton. Indigo dyers in 19th century Korea were differentiated from the rest of the dyers. They managed the growing of indigo plants as well as the production of indigo sediment (jeon). Woad dyers in 19th century England handled woolen cloth as well as worsted and woolen yarn in general. However, they sometimes dyed silk skein as well. They produced several colors such as black, blue, slates, grays, by using both woad and imported indigo.
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Seasonal production is the major issue impeding industrial production of plant indigo. Indican is the major precursor in fresh Strobilanthes cusia leaves for indigo production. The change in indican content of leaves during storage was investigated to propose a novel process for all-season indigo production in this study. Little indican was detected in leaves after 144 h even at 4 °C. Hydrolysis of indican by β-glucosidase was the main cause for the indican decrease. Heat drying led to a significant decrease in the β-glucosidase activity. However, the increasing rate of temperature was not enough to rapidly inactivate the β-glucosidase activity, and the residual β-glucosidase activity led to a decrease in indican content from 85.86 mg/g DW to 9.43 mg/g DW at 105 °C within 5 min. Microwave drying could increase the internal temperature of leaves rapidly such that β-glucosidase was immediately inactivated. The components of microwave-dried leaves were close to those of fresh leaves, especially for indican, which was maintained stably for 32 weeks. The indigo production with microwaved leaves provided an indigo yield of 20.00 mg/g DW, which was 2.4 times higher than that with fresh leaves. The result indicated the feasibility of an all-season production of plant indigo with the new approach.
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