Color Reduction Research Articles

Improving the Speed and Quality of Parallel Graph Coloring

Graph coloring assigns a color to each vertex of a graph such that no two adjacent vertices get the same color. It is a key building block in many applications. In practice, solutions that require fewer distinct colors and that can be computed faster are typically preferred. Various coloring heuristics exist that provide different quality versus speed tradeoffs. The highest-quality heuristics tend to be slow. To improve performance, several parallel implementations have been proposed. This paper describes two improvements of the widely used LDF heuristic. First, we present a “shortcutting” approach to increase the parallelism by non-speculatively breaking data dependencies. Second, we present “color reduction” techniques to boost the solution of LDF. On 18 graphs from various domains, the shortcutting approach yields 2.5 times more parallelism in the mean, and the color-reduction techniques improve the result quality by up to 20%. Our deterministic CUDA implementation running on a Titan V is 2.9 times faster in the mean and uses as few or fewer colors as the best GPU codes from the literature.

Enhancing the Efficiency of Banana Peel Bio-Coagulant in Turbid and River Water Treatment Applications

The aim of the present work is to investigate the potential use of banana peel waste as a natural coagulant and to enhance its coagulation performance using a green modification approach for the removal of synthetic water turbidity and river water treatment. Here, the regular banana peel powder had an average particle size and diameter of 978 ± 37 nm and 602 ± 13 nm, respectively, while the modified powder possessed 571 ± 41 nm and 360 ± 19 nm particle size and diameter, respectively. The coagulation performance was investigated at different pH levels, doses, sedimentation times, and NaCl quantities. The optimum dose was found to be 0.4 g/L for modified banana peel with turbidity removal of up to 90%. NaCl slightly enhanced the coagulation performance at low quantities of less than 0.4 g/L, but the activity was reduced at higher concentrations even in the modified powder. Banana peel powder had a weaker turbidity reduction of 76 and 84% for non-modified and modified powders in river water, respectively, in addition to significant reduction in water color, total dissolved and suspended solids, and chemical and biochemical oxygen demand. SEM and FT-IR characterization were performed to investigate and confirm the coagulation mechanism. Such a green modification of banana peel powder can be an alternative with significantly potential as a low cost and easily available bio-coagulant, which can certainly contribute to the waste reduction.

Anaerobic biological treatment of dye bearing water in anaerobic sequencing batch reactor: Performance and kinetics studies

Textile and dye industries are main sources of dye bearing effluent. In present studies the anaerobic biological degradation of Acid Red 3BN dye water (AR3BNDW) and mixed dye water (MDW) for reduction of color and COD were studied in sequential batch reactor (SBR). The sludge as sources of microorganism was arranged from maize processing bio methanation wastewater treatment plant, which was acclimatized for treatment of AR3BNDW and MDW. After the acclimatization, dyes degradation were studied in SBR At optimum operation condition of hydraulics retention time (HRT) = 2.5 d, and treatment time (tR) = 16 h, AR3BNDW have gone maximum 87% color reduction of 500 mg/L dye, and 82.8% COD reduction of 380 mg/L COD. At same operating condition, 84.5% color reduction of 500 mg/L dye, and 79.42% COD reduction of 413 mg/L COD achieved for MDW. The second order Grau model was fitted well for COD and dye reductions. The kinetics parameter were evaluated for both the dye water.

Distillery industrial wastewater(DIW) treatment by the combination of sono(US), photo(UV) and electrocoagulation(EC) process

The color and Chemical Oxygen Demand (COD) reduction in distillery industrial effluent (DIW) was investigated utilizing photo (UV), sono (US), electrocoagulation (EC), UV + US, UV + EC, US + EC, and US + UV + EC technologies. The empirical study demonstrated that the UV + US + EC process removed almost 100% of color and 95.63% of COD from DIW while consuming around 6.97 kWh m−3 of electrical energy at the current density of 0.175 A dm−2, COD of 3600 mg L−1, UV power of 32 W, US power of 100 W, electrode pairings of Fe/Fe, inter–electrode distance of 0.75 cm, pH of 7, and reaction time of 4 h, respectively. The values found were much greater than those produced using UV, US, EC, UV + US, UV + EC, and US + EC methods. The influence of various control variables such as treatment time (1–5 h), current density (0.075–2.0 A dm−2), COD (1800–6000 mg L−1), inter-electrode distance (0.75–3.0 cm), electrode pairings (Fe/Fe, Fe/Al, Al/Fe, Al/Al), UV (8–32 W), and US (20–100 W) on the color and COD reduction were investigated to determine the optimum operating conditions. It was observed that, an increase in treatment time, current density, UV and US power, decrease in the COD, and inter-electrode distance with Fe/Fe electrode combination improved the COD removal efficiency. The UV and US + EC processes' synergy index was investigated and reported. The results showed that, the US + UV + EC treatment combination was effective in treating industrial effluent and wastewater.

Phenotypic and genotypic characterisation of pepper genotypes for Tomato Spotted Wilt Orthotospovirus reaction and resistance

In order to determine the effects of Tomato spotted wilt orthotospovirus (TSWV) on the yield and fruit quality parameters of some common local and commercial pepper (Capsicum annuum L.) genotypes under greenhouse conditions, mechanical inoculations were performed, and virus infections were tested by DAS-ELISA and RT-PCR after the inoculations. Based on the DAS-ELISA results, 95% of the inoculated plants were found to be positive for TSWV, in accordance with the expected amplicon size (276 bp) obtained by RT-PCR results. Infection of TSWV caused significant (p≤0.05) reduction in fruit number (45.97-100%), fruit weight (66.38-98.77%), fruit width (63.77-96.52%), fruit length (31.97-93.514%), flesh thickness (28.64-82.41%), fruit firmness (5.82-94.43%), fruit colour (1.62-7.79%), and total yield (68.62-100%) in infected plants. The best performance against TSWV was observed on cv. Yalova Çarliston 341, while the lowest was observed on cv. Bora 77 among the tested pepper cultivars Yalova Çarliston 341, Yalova Tatlı Kıl, Yalova Yağlık 28, Mazamort, Sera Demre 8, Üçburun, Geyikboynuzu, Bor Biberi, Bora 77 and 153-227. Moreover, the incidence of Tsw resistance gene was investigated by molecular analysis using CAPS marker SCAC568 with TaqI restriction enzyme digestion; however, Tsw gene could not be detected in any of the tested cultivars except wild type C. chinense and resistant genotype cv.153-227. This study reveals the effects of TSWV in common pepper genotypes and will be important for virus resistant breeding studies.

Screening of Used Engine Oil degrading Bacteria by 2-6 DCPIP Assay

Lubricating engine oil which is used in vehicles and machines to keep them running smoothly, is frequently released during automobile engine servicing or illegally dumped, posing a significant environmental threat because it is less volatile than other types of petroleum fuels and remains in the soil for longer periods of time. To solve this problem, new environmentally friendly techniques must be created. Considering the same, the current investigation, was carried out to screen and evaluate the oil-degrading capability of bacterial isolates from oil-contaminated soil collected from different sites of Udaipur city. The isolation was done on Luria-Bertani agar using the pour plate method. The primary screening of the isolates for used engine oil degradation was done on Bushnell Haas mineral salt agar medium using the spot inoculation method. The 2,6-DCPIP (2,6-Dichlorophenol indophenol) indicator was used to determine the oil degrading efficiency of isolates. A total of ten soil samples contaminated with used engine oil were collected from two distinct locations of Udaipur city. A total of seventy eight bacterial isolates were recovered using pour plate method from various soil samples on LB (Luria-Bertani) agar at 370C after 24 hours of incubation period. Twelve bacterial isolates out of seventy eight showed zone of clearance, indicating oil degrading capability. The diameter for zone of clearance of 12 isolates ranged between 5 to 15 mm. All 12 isolates demonstrated DCPIP decolorization. Color reduction percentage ranged from 68.66 % to 98.57 % for 12 oil-degrading bacterial isolates. Isolate ODB 29 showed the highest color reduction (98.57 %). These isolates may be explored for their possible use in bioremediation.

Combination of electrocoagulation with solar photo Fenton process for treatment of landfill leachate

ABSTRACT The aim of the present work was to provide a viable and active way to remove COD and colour from landfill leachate treated by adopting combined process of electrocoagulation and solar photo Fenton process. Coagulating agents such as metal hydroxides are created by the electrolysis process through self-sacrificial electrodes. Aluminium and iron dissolves at the anode and hydrogen gas are generated at the cathode when aluminium and iron electrodes are utilised. The contaminants interact with the coagulating agent to generate enormous organic flocs. The leachate was obtained from a landfill in Madurai and then it was characterised in terms of its major predominant pollutants. In this study, the electrocoagulation process was used in conjunction with the solar photo Fenton process to treat the leachate under ideal conditions of pH = 7, NaCl = 2 g/L, voltage = 4 V, Al & Fe electrodes and inter electrode distance = 3 cm with a COD and colour removal effectiveness of 75% and 76%, respectively. Furthermore, the effluent from the electrocoagulation process was treated using a solar photo Fenton process at pH = 3, H2O2 = 10 g/L and Fe2+ = 1 g/L with COD and colour reduction effectiveness of 90% and 91%, respectively. In this combination of treatment systems, leachate biodegradability increased from 0.35 to 0.73, favouring the biological oxidation process in conventional treatment plants. This research demonstrates that employing this paired electrocoagulation–solar photo Fenton to treat landfill leachate can achieve consistent treatment effects with high removal efficiencies, and that it is an acceptable treatment technique for landfill leachate.

Passive Framework of Sparse Region Duplication Detection from Digital Images

Currently, digital images are widely communicated by media using social media applications. The general public captures the digital images for preserving the family and personal memories and to share with their friends and family. Digital images have been used extensively in forensic science to present the digital images as proof in the court and law enforcement agencies, which present a loophole for the culprits to forge the digital image and change the proofs and evidence. Copy-move forgery (CMF) is among the most widely employed image manipulation methods. In this method, the area of the image is duplicated to some other part to modify its content by applying different postprocessing operations on images like blurring, color reduction, and scaling which is a challenging research problem in copy-move forgery detection (CMFD). In this paper, an efficient and effective CMFD method is presented to identify the single and multiple altered areas in an image in the presence of postprocessing operations. The proposed CMFD method divides the image into circular blocks. It computes a rotation-invariant feature vector from each circular block of the image by applying local intensity order pattern (LIOP) features. The computed feature vectors are then compared using Euclidean distance to locate the suspected image’s forged areas. The experimental results of the proposed CMFD method are reported on three standard datasets of the CMF, namely, CoMoFoD, KLTCI, and MICC-F220. The experimental analysis of the proposed CMFD method on these datasets indicates that it produces robust performance (detection accuracies of 97.29% on the CoMoFoD dataset, 98.53% on the KLTCI dataset, and 97.57% on the MICC-F220 dataset) as compared with state-of-the-art CMFD methods in terms of the standard performance evaluation parameters of the CMF.

Aliphatic oxime 3-(hydroxyimino)pentan-2,4-dione as new potential mediator for laccase-catalyzed decolorization of dyes

Aliphatic oxime HIPD (3-(hydroxyimino)pentan-2,4-dione) was studied as mediator of laccase (from Trametes versicolor) catalyzed decolorization and detoxication of eight structurally diverse synthetic dyes with typical chromophores including the azo dyes (Acid Red 1, Methyl Orange and Mordant Blue 13), indigo dye (Indigo Carmine), triphenylmethane dyes (Methyl Green, Crystal Violet), anthraquinone dye (Reactive Blue 4) and thiazine dye (Methylene Blue). The results demonstrated the potential and limitations of using 3-(hydroxyimino)pentane-2,4-dione as mediator for enzymatic decolorization of various type dyes. In the presence of a laccase-mediator system almost 100 % biodegradation was observed for Indigo Carmine, Acid Red 1, Methyl Orange and Reactive Blue 4 within 3 h. At the same time, the proposed laccase-mediator system does not decolorize Methylene Blue and exhibits lower efficiency in the degradation of triphenylmethane dyes in comparison with azo dyes. The studied system can be used repeatedly for wastewater treatment. Phytotoxicity tests of the solutions before and after treatment with laccase-mediator system indicated that dyes are converted into low-toxicity metabolites. The proposed system has demonstrated its efficiency in the treatment of artificial wastewater containing high concentrations of azo dyes (0.5 g L−1) and other auxiliaries used in the textile industry. Color reductions of 92 % and 83 % were achieved using laccase-mediator system for Acid Red 1 and Methyl Orange for 7 days in the presence of dye bath components.

Clarification of sugarcane (Saccharum officinarum) vinasse for microalgae cultivation

The use of the nutrients present in vinasse to grow microalgae is limited due to the high color and turbidity. Thus, the aim of this work was to investigate the ecofriendly low-cost Moringa oleifera seed (paper or glass filtered), M. oleifera seed + activated charcoal, and activated charcoal as alternative replacers of Tanfloc MT, Praestol Solenis 2530 polymer, iron III chloride (FeCl3), aluminum sulfate (Al2(SO4)), and calcium hydroxide (Ca(OH)2) on the clarification of vinasse. It was also evaluated the vinasse diluted in distilled water up to 50 %. pH, color (455 nm) and turbidity (860 nm) were measured in triplicates to evaluate the clarification processes. M. oleifera seed glass filtered was the most efficient in clarifying the vinasse with a higher percentage of color and turbidity reduction obtained using 30 g L−1 of seed, with 68.92 % and 78.78 % reduction, respectively. This level of clarification turns the vinasse indicated for microalgal cultivation.

Effects of the repression of GIGANTEA gene StGI.04 on the potato leaf transcriptome and the anthocyanin content of tuber skin

BackgroundGIGANTEA (GI) is a plant-specific, circadian clock-regulated, nuclear protein with pleiotropic functions found in many plant species. This protein is involved in flowering, circadian clock control, chloroplast biogenesis, carbohydrate metabolism, stress responses, and volatile compound synthesis. In potato (Solanum tuberosum L.), its only role appears to be tuber initiation; however, based on findings in other plant species, we hypothesised that the function of GI in potatoes is not restricted only to tuberisation.ResultsTo test this hypothesis, the expression of a GI gene in the commercial potato cultivar ‘Désirée’ was repressed, and the effects of repression at morphological and transcriptome level were investigated. Previously, two copies of GI genes in potato were found. A construct to reduce the mRNA levels of one of these genes (StGI.04) was assembled, and the effects of antisense repression were studied in greenhouse-grown plants. The highest level of repression reached around 50%. However, this level did not influence tuber formation and yield but did cause a reduction in tuber colour. Using high-performance liquid chromatography (HPLC), significant reductions in cyanidin 3,5-di-O-glucoside and pelargonidin 3,5-di-O-glucoside contents of tuber peels were detected. Anthocyanins are synthesized through a branch of the phenylpropanoid pathway. The transcriptome analysis indicated down-regulation in the expression of PHENYLALANINE AMMONIA LYASE (PAL), the LEUCOANTHOCYANIDIN OXIDISING enzyme gene LDOX, and the MYB-RELATED PROTEIN Hv1 (MYB-Hv1), a transcription factor coding gene, which is presumably involved in the regulation of flavonoid biosynthesis, in the leaves of a selected StGI.04-repressed line. Furthermore, alterations in expression of genes affecting the circadian clock, flowering, starch synthesis, and stress responses were detected in the leaves of the selected StGI.04-repressed line.ConclusionsWe tested the effects of antisense repression of StGI.04 expression in potatoes and found that as with GI in other plant species, it influences the expression of the key genes of the circadian clock, flowering, starch synthesis, and stress responses. Furthermore, we detected a novel function of a GI gene in influencing the anthocyanin synthesis and potato tuber skin colour.

Linial for lists

Linial’s famous color reduction algorithm reduces a given m-coloring of a graph with maximum degree varDelta to an O(varDelta ^2log m)-coloring, in a single round in the LOCAL model. We give a similar result when nodes are restricted to choose their color from a list of allowed colors: given an m-coloring in a directed graph of maximum outdegree beta , if every node has a list of size varOmega (beta ^2 (log beta +log log m + log log |{mathcal {C}}|)) from a color space {mathcal {C}} then they can select a color in two rounds in the LOCAL model. Moreover, the communication of a node essentially consists of sending its list to the neighbors. This is obtained as part of a framework that also contains Linial’s color reduction (with an alternative proof) as a special case. Our result also leads to a defective list coloring algorithm. As a corollary, we improve the state-of-the-art truly local({text {deg}}+1)-list coloring algorithm from Barenboim et al. (PODC, pp 437–446, 2018) by slightly reducing the runtime to O(sqrt{varDelta log varDelta })+log ^* n and significantly reducing the message size (from varDelta ^{O(log ^* varDelta )} to roughly varDelta ). Our techniques are inspired by the local conflict coloring framework of Fraigniaud et al. (in: FOCS, pp 625–634, 2016).

Optimization of electrocoagulation process for treatment of rice grain-based biodigester distillery effluent using surface response methodology approach

Abstract Distillery industries are the most water-consuming industries discharging a large amount of wastewater that contain a high organic load. Hence it is first treated in biodigester where significant organics reduces (50–60%) and the outcome of biodigester is commonly known as biodigester effluent (BDE). The present study is an attempt to treat BDE in terms of COD and color removal using a batch electrocoagulation reactor (ECR) where stainless steel (SS) is used as an electrode. To optimize the four independent parameters namely initial pH (pHi: 3.5–9.5), current density (j: 49.5–247 A/m2), electrode gap (g: 1.2–3.2 cm), and reaction time (t: 20–100 min) on the color and COD reduction efficiency, a central composite design (CCD) experiment is applied to evaluate the individual and interactive effects of these parameters. The high coefficients of determination for color (R 2 = 0.9989) and COD (R 2 = 0.9981) were obtained by analysis of variance (ANOVA) between the experimental data and the predicted data using a second-order regression model. At the optimum condition color and COD removal of 81.4 and 91.9%, respectively, were observed. A material balance of SS has also been incorporated.

Effect of ZnO/(Co or Mn) ratios on the structure and optical spectroscopy parameters of PVA/PVP/PEG blended polymer

In this work, doped polyvinyl alcohol/polyvinyl pyrrolidone/polyethylene glycol (70%PVA/20%PVP/10%PEG) blended polymers with different amount of nano ZnO (Zn0.95X0.05O, X = Co and Mn) were produced using solid reaction and casting procedures.The structure and microstructure of the nanofiller samples and blended polymers were investigated using X-ray diffraction (XRD), Energy-dispersive X-ray analysis; scanning electron microscope and Fourier transform infrared techniques. XRD confirmed the present of the nanofiller over the blend matrix. The effect of kind and ratios of the nanofiller on the degree of crystallinity, transmittance, reflectance, absorbance, extinction coefficient, refractive index, dielectric properties and optical conductivity of the blends was examined using diffused reflectance technique. The optical band gap (Eg) value for PVA/PVP/PEG blend is 3.43 eV and it reduced to 2.57 or 2.71 eV as the blend doped with ZnO/Co or ZnO/Mn, respectively. A 500 nm, the n value for the blend doped with 5 wt % ZnO/Co is 1.67 while the n value for the blend doped with 5 wt % ZnO/Mn is 1.51. All nonlinear optical parameters were enhanced as the blend doped with 5 wt % (ZnO/Co or ZnO/Mn). The rate of reduction of fluorescence intensity and emitted colors from different blends were affected by the kind and amount of the nanofiller.

Aesthetic Periodontal Surgical Approach for Preparing Direct Veneer: A Case Report

Background: Gingival enlargement is caused by cervical dental plaque accumulation and worsened by cervical caries. Gingivectomy, gingivoplasty and ablation procedures are the surgical techniques used to improve the aesthetics and physiologic functions of hyperpigmented fibrotic gingival tissues.
 Objective: To provide aesthetic satisfaction to patients treated for direct veneer restoration.
 Case Report: A 19-year-old male patient came to RSGM UNHAS with a chief complaint of caries on the right maxillary incisors, extending from labial to cervical sections, showing gingival enlargement of the teeth. Intraoral examination revealed caries and gingival enlargement with uneven gingival color. Gingivectomy, gingivoplasty and ablation were performed on the patient using a scalpel, then direct veneer restorations were performed.
 Results: The two-week control period showed reduction in gingival enlargement and uniform gingival color.
 Conclusion: A periodontal aesthetic surgy in the form of gingivectomy, gingivoplasty, and ablation maximizes esthetic results.
 Keywords: ablation, direct veneer, gingivectomy, gingivoplasty

Optimization of process variables for reduction of genotoxicity from paper mill effluent

In recent years, microbial techniques for wastewater degradation process optimization under laboratory circumstances have piqued the interest of many academics acress the word, prompting them to investigate practical, cost- effective and long-term wastewater treatment technologies. Some workers claim that certain metabolic compounds have mutagenic nature and endocrine disrupting properties. To confirm the degradation and identification of a variety of metabolic products that may have EDC properties, control and bacterial treated samples were analyzed with the help of HPLC and GC-MS.In this study, toxicity assessment (genotoxicity) were performed to confirm the load of various EDCs present in the RGP effluent.Glucose was the most abundant among the carbon sources used as it showed the greatest reduction in colour (61.93%) and COD (57.86%) at 96 hours of the incubation period. However, galactose and sucrose were also found to be very good, allowing 56% color and 48.4% COD reduction. Sodium nitrate, which is an inorganic nitrogen source, played an important role in pulp paper mill effluent decolorization as well as COD reduction. On the other hand, a negative contribution to the color reduction was shown by the inorganic nitrogen source ammonium nitrate.

Treatment of printing ink wastewater using a continuous flow electrocoagulation reactor

Printing ink wastewater from printing facilities is difficult to treat because of its heavy pollutant load (chemical oxygen demand - COD, color and total suspended solids - TSS). In this study undiluted printing ink wastewater with high COD (i.e., 20,000 mgL−1) was treated using a highly efficient, continuous flow electrocoagulation reactor with aluminum electrodes. The parameters investigated were: initial COD concentration (4000, 10,000 and 20,000 mgL−1), current density (21, 42 and 83 mAcm−2), and inlet flow rate (6, 8 and 10 mLmin-1). All parameters showed great efficiency in terms of pollutant removal for diluted printing ink wastewater. For undiluted printing ink wastewater treatment, COD, color, and TSS removal were maximized at 6 mLmin-1 flow rate reaching 82%, 98%, and 85% COD, color, and TSS removal, respectively, by applying the lower tested current density 21 mAcm−2. COD, color and TSS removal increased with increasing current density. For undiluted printing ink wastewater and a flow rate of 8 mLmin-1, COD removal was between 42 and 88%, color reduction between 85 and 99%, and TSS reduction between 83 and 98% when the applied current was increased (from 21 to 83 mAcm−2). Lower pollutant removal was observed at the highest flow rate of 10 mLmin-1 for all current densities tested. Process cost calculations in terms of electrical energy, electrode material consumption and sludge disposal, showed that the use of continuous flow electrocoagulation reactor (with flow rate 6 mLmin-1, and at 21 mAcm−2) is an affordable and effective treatment method for printing ink wastewater streams with very high COD. Sludge characterization showed Al-silicate-rich sludge. Particle sizes increased after treatment and Cu and Ti were detected in the sludge. A post-treatment stage is necessary before discharging effluent into water bodies.

Genital whitening with topical Cyperus rotundus oil enhances sexuality and quality of life.

Cyperus rotundus essential oil (CREO) is an anti-inflammatory and depigmenting agent that helps treat hyperpigmentation. The purpose of this study was to evaluate the depigmenting effect of CREO on genital hyperpigmentation to that of arbutin (ARB), and to evaluate the association between genital lightening, genital self-image, sexual performance, and life quality. Three hundred and eight healthy people were categorized into three groups: the CREO group, the ARB group, and the cold cream group (CC). In genital pigmentation, the tristimulus colorimeter is used to assess erythema and pigmentation. In addition, we aided in the development of the female genital self-image scale (FGSIS-4), the female sexual function index (FSFI), and the dermatology life quality index (DLQI). The reduction in genital hyperpigmentation was significantly greater in the CREO and ARB groups than in the CC group; in physician global assessment and patients' self-assessment, the results in treated bikini with the CREO and ARB groups were excellent when compared with the CC. Furthermore, no adverse effects were found in the CREO group, but mild irritation was found in the ARB group; additionally, the percentage of hair growth, color and luminance reduction, and hair thickness were significantly reduced in the CREO group only. In addition, there were significantly different in FGSIS, FSFI, and DLQI between the CREO and ARB groups and the CC group. CREO is equivalently efficacious in decreasing pigmentation, inflammation, and hair growth in the genital area. Positive changes boost female genital self-image, self-esteem, and sexual performance. Improving sexual health has a positive impact on quality of life.

A precise self-built secondary mass database for identifying red dyes and dyeing techniques with UPLC-MS/MS.

Dyes on ancient silks have been a worth studying field through human's history, although current reports ignore the connection between natural dyes origin and relevant colour reduction methods, which poses an insurmountable obstacle for restoration of historical silks. In this paper, a series of 12 red hue silks from six natural dyes (sappanwood, Chinese madder, safflower, lac, cochineal, dragon's blood) via three different dyeing techniques were used to establish a self-built precise tandem mass spectrometry (MS/MS) database. With organic solvent extracting on those manual-dyed silks, ultraperformance liquid chromatography - electrospray ionization - quadrupole time of flight mass spectrometry (UPLC-ESI-QTOF-MS) was utilized to form preliminary MS database for screening and identifying of the potential dyes compounds without standard references. Furthermore, combining the targeted MS/MS mode and the matching threshold of 70.00, a self-built secondary MS/MS database was successfully established, which contains 33 compounds, 32 chromatograms and 32 MS/MS fragments. As for real sample application, the self-built precise MS/MS database had revealed that the dyes on two historical silks (Shanghai Museum, China) belong to Chinese madder just with different mordant dyeing ordinal. Additionally, by experimental restoration, visually indistinguishable silks (ΔEab* < 1.5 NBS) were successfully restored. This explorative methodology can further inspire the traceability of biological dyestuffs, which lays instructive foundation on protection and restoration of artefacts, connecting the archaeological science and human art.

Mechanism of pH sensitive flocculation for organic load and colour reduction in landfill leachate

Landfill leachate has an important fraction of humic substances, mainly humic acids (HAs), which often represent more than half value of COD, specially in liquids proceeded from composting processes of organic fraction of solid wastes. We propose in this article a new method of pH sensitive flocculation for COD and colour reduction in landfill leachate based on the chemical properties of HAs. Landfill leachate with a high content of humic acids can be efficiently treated by pH sensitive flocculation at pH 2.0, reducing COD value in 86.1% and colour in 84.7%. Mechanism of pH sensitive flocculation is based in protonation first of phenolic groups and later of carboxylic acid groups in the HAs molecules, resulting in a reduction of Zeta potential value. For pH over neutrality, carboxylic acid and phenolic groups are ionized and Zeta potential increases in absolute value, maintaining HAs in suspension as colloids and conducting flocculation to be obstructed. Ionized anionic groups (carboxylates) can interact electrostatically with cations abundant in leachate (site binding) aiding to maintain HAs in suspension. Simulation of this situation and ideal visualization of Zeta potential behavior is described in the paper and aggregation of molecules by H-bonds is proposed as the main step in separation of HAs from leachate and reduction of COD value in this complex liquid. CHNS analysis, FT-IR spectrometry and UV–VIS spectrophotometry show chemical elements content in the range of natural and commercial HAs, clear aromaticity and carboxylic acids and phenolic groups presence in the precipitate from landfill leachate.