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The effects of harsh UV radiation (λ = 254 nm) on wool and silk dyed with Hexaplex (Murex) trunculus extract are investigated using HPLC-DAD, colourimetry, SEM and FTIR. Indigotin, 6-bromoindigotin, 6,6′-dibromoindigotin and 6,6′-dibromoindirubin were quantified by an efficient HPLC-DAD method which was validated in terms of linearity, detection and quantification limits, precision and accuracy. Under optimal conditions, the developed analytical scheme offers limits of detection in the range 0.02–0.12 μg mL−1 and satisfactory linearity up to 5.0 μg mL−1. The purple dyes, extracted from the wool and silk fibres, were analysed by the established HPLC method, using the standards addition approach. To evaluate the matrix effect, the matrix-induced signal suppression/enhancement was determined. The accuracy was evaluated by recovery experiments. The effect of the UV light was initially dramatic, leading to (i) a rapid decrease in the amounts of the four shellfish compounds in the wool/silk fibres and (ii) severe colour changes of the dyed fibres. After extensive (>10 days) exposure in harsh UV light, only slight changes in the dye composition and the colour of the fibres were observed. Overall, larger reductions are reported in the amounts of the dibrominated molecules, whereas indigotin and 6-bromoindigotin appear to be more stable against the UV radiation. However, it is reported that the % relative composition of the shellfish dye is practically unaffected by the degradation process. Finally, the UV-induced structural and chemical changes of the wool and silk fibres were investigated using SEM and FTIR, respectively.

In this work, a computational systems approach, comprising models at different time and length scales, is developed to elucidate the fundamental chemical, physical, transport, and biological proces...

A HPLC method coupled with diode array detector was developed and validated for the quantitation of alizarin, apigenin, carminic acid, curcumin, ellagic acid, emodin, fisetin, kaempferide, kaempferol, kermesic acid, morin, purpurin, quercetin and sulfuretin which are components of several natural dyes. 1- Hydroxyanthraquinone was selected as internal standard. The compounds were separated under gradient elution on a RP-column (Altima C18, 250 mm x 3.0 mm i.d., 5 μm) with a mobile phase consisting of solvent A: H2O + 0.1% (v/v) trifluoroacetic acid and solvent B: acetonitrile + 0.1% (v/v) trifluoroacetic acid. The method was validated in terms of linearity, limits of detection and quantitation, accuracy, precision, ruggedness and robustness and applied to the analysis of silk dyed with buckthorn (Rhamnus trees), cochineal (Dactylopius coccus Costa), madder (Rubia tinctorum L.), turmeric (Curcuma longa L.) and young fustic (Cotinus coggygria Scop). Furthermore, dyed silk samples were subjected to artificially accelerated ageing conditions induced by UV radiation. The effect of the latter on the quantities of the aforementioned compounds was monitored, except for apigenin, kermesic acid and morin.

An integrated metabolic-polymerization-macroscopic model, describing the microbial production of polyhydroxybutyrate (PHB) in Azohydromonas lata bacteria, was developed and validated using a comprehensive series of experimental measurements. The model accounted for biomass growth, biopolymer accumulation, carbon and nitrogen sources utilization, oxygen mass transfer and uptake rates and average molecular weights of the accumulated PHB, produced under batch and fed-batch cultivation conditions. Model predictions were in excellent agreement with experimental measurements. The validated model was subsequently utilized to calculate optimal operating conditions and feeding policies for maximizing PHB productivity for desired PHB molecular properties. More specifically, two optimal fed-batch strategies were calculated and experimentally tested: (1) a nitrogen-limited fed-batch policy and (2) a nitrogen sufficient one. The calculated optimal operating policies resulted in a maximum PHB content (94% g/g) in the cultivated bacteria and a biopolymer productivity of 4.2 g/(l h), respectively. Moreover, it was demonstrated that different PHB grades with weight average molecular weights of up to 1513 kg/mol could be produced via the optimal selection of bioprocess operating conditions.

Quantitative HPLC and colorimetry are used to study color variations in dyeings with indigo, 6-bromoindigo, and 6,6′-dibromoindigo, the main components of the historic dye Tyrian purple. For the first time, visible light is identified conclusively as a cause of debromination of the leuco form of 6-bromoindigo. A dyeing run using 6-bromoindigo alone is found to yield a dyed fabric containing large amounts of indigo, when the vat is exposed to visible light. The extent of debromination is dependent upon the pH of the dye bath and also the source of the visible light. This information allowed development of a dyeing procedure which is demonstrated to give consistent colors through two passes. Quantitative HPLC analysis of extracts from the dyed fabrics indicates that the leuco form of 6-bromoindigo vs. the leuco forms of indigo and 6,6′-dibromoindigo has the strongest affinity for wool fabric. This is postulated to be due to attractive electrostatic interactions between the leuco form of 6-bromoindigo and wool.

A process systems approach towards the development and integration of computational models to describe the application, adhesion, spreading, and stability of a reacting hyaluronic acid gel onto the Olfactory mucous layer as well as the release of drug from particles dispersed in the hydrogel matrix, diffusion, and transfer through the mucous layer is described. The initial results from this systems approach reveal the connection between the physico-chemical processes which can lead to design limitations, e.g., gel extrusion time influences the extent of spreading on the mucous layer.

Indigotin, indirubin, 6-bromoindigotin, 6'-bromoindirubin, 6-bromoindirubin, 6,6'-dibromoindigotin and 6,6'-dibromoindirubin, the colouring components of Tyrian purple, are quantified by an efficient HPLC method coupled to a diode array detector. The compounds were separated using gradient elution, on a RP-column (Alltima C18, 250mm×3.0mm i.d., 5μm), thermostated at 35°C, with a mobile phase consisting of solvents (Α) H2O+0.1% (v/v) trifluoroacetic acid and (Β) acetonitrile+0.1% (v/v) trifluoroacetic acid, at a flow rate of 0.5mLmin(-1). The method was validated in terms of linearity, detection and quantification limits, precision, accuracy, ruggedness and robustness, the latter with respect to small changes in column temperature and in flow-rate, pH- and solvent composition of the mobile phase. Under optimal conditions, the developed analytical scheme offers limits of detection in the range 0.02-0.05μgmL(-1) and satisfactory linearity up to 2.5μgmL(-1) for all analytes. Four samples produced from the hypobranchial glands of Hexaplex (Murex) trunculus molluscs, collected in the coastlines of Tunisia and Croatia, were treated with hot DMSO and analysed by the established HPLC method, using the standards addition approach. To evaluate the matrix effect, a comparison of the slopes of the standards in solvent regression curves with those of the standard addition method's calibration curves, using the Student's t-test was carried out. The accuracy was evaluated by recovery experiments. Amounts of indigotin, indirubin, and their mono- and dibrominated derivatives ranging between 0.01 to 12.2μgmg(-1) were found in the DMSO extracts of the four molluscan samples.