Pigment Mixtures Research Articles

The cytotoxicity of cyclophosphamide is enhanced in combination with monascus pigment.

Monascus pigment is derived from red-mold rice fermented by monascus purpureus and utilized as a natural coloring agent and natural food additive in East Asia. Monascus pigment works as a radical scavenger. Some antioxidant combine cancer chemo­therapy to protect normal tissue because chemotherapy induce side effect for normal tissue. This combination therapy can attenuate the cytotoxicity of anti­cancer drugs by antioxidants effects. However, the effect of this combination therapy for cancer cells dose not investigate enough. In this study, we investigated the combination effect of anti­oxidants and anti­cancer drugs. We selected an anti­oxidant as monascus pigment and following four anti­cancer drugs: doxorubicin, tamoxifen, paclitaxicel, and cyclophosphamide. Combination treatment with monascus pigment and cyclophosphamide enhanced the cytotoxicity of cyclophosphamide. Moreover, this combination treatment accelerated apoptosis. The spot on TLC assay board of the monascus pigment and cyclophosphamide mixture is different from the spot of monascus pigment alone and cyclophosphamide alone. The interaction between monascus pigment and cyclo­phosphamide can produce some cytotoxicity compounds or accelerate intracellular cyclophosphamide accumulation. Hence, we concluded that the interaction of both cyclophosphamide and monascus pigment involved enhancement of cyclophosphamide cytotoxicity.

The Irreplaceable Contribution of Cross Sections Investigation: Painted Plasters from the Sphinx Room (Domus Aurea, Rome)

Fragments and micro-fragments of painted plasters from the Sphinx Room, recently discovered in the Domus Aurea Esquiline wing (Rome, Italy), were studied. They were respectively taken from the debris in the vicinity of the walls and from already damaged edges of the decorated walls. A previous study, mainly based on non-destructive and non-invasive investigations, proved effective in giving a general overview of the employed palette, allowing the comparison with paintings from the same palace and other coeval contexts, and also providing some preliminary hints concerning the pictorial technique. Nevertheless, some issues remained unsolved, concerning the pigment mixtures (e.g., lead-/iron-based yellow to red colors; copper-/iron-based green/greyish areas), and the a fresco/a secco painting technique debate. Therefore, cross sections of the above-mentioned fragments were observed by means of Optical (OM) and Scanning Electron (SEM) Microscopy and analyzed with micro-Raman spectroscopy and Energy Dispersive X-Ray Spectroscopy (EDS), with the aims of: studying the paint layer composition through point analysis and mapping of the elemental distribution; comparing these in relation to what was observed with previously reported non-destructive analyses; studying the stratigraphy of the painted plaster, focusing on the contact between the plaster and the paint.

A Tale of Two Tiles: Characterization of Floor Tiles from the Nineteenth-Century Akko Tower Shipwreck (Israel)

Fragments of decorated floor tiles were retrieved from the Akko Tower shipwreck, Israel. Most tiles were made of bright brown fired clay with a white glaze decorated with colored stenciled motifs (Type A); and others consisted of a red-brown fired clay body, coated with a brown pigment covered with transparent brown glaze (Type B). This study aimed to characterize the two tile types; to reveal information concerning the manufacturing process; and to determine the origin of their raw material. A multidisciplinary approach was used, including light microscopy, SEM-EDS, electron probe microanalysis with wavelength-dispersive X-ray spectroscopy (EPMA-WDS), XRD, Raman spectroscopy, and time-of-flight secondary ion mass spectrometry (TOF-SIMS) analyses. The characterization of both tile types demonstrated the use of different raw materials. The Type A tiles were covered with tin-opacified majolica glaze and colored with various mixtures of pigments. The blue color was due to pigment rich in cobalt; the yellow color was due to Naples yellow and lead-tin yellow I minerals; and the green, orange, and brown colors were all prepared by mixing the Naples yellow pigment with different minerals. These majolica glaze tiles were probably manufactured in Sicily. The brown coating of the Type B tiles was due to pigment rich in lead and iron minerals. These tiles were produced with different manufacturing processes, and apparently made in France.

Enforcing Kubelka–Munk constraints for opaque paints

AbstractThe Kubelka–Munk model relates the colours of paint mixtures to the absorption and scattering coefficients (K and S) of the constituent paints, and to their concentrations (C) in the mixtures. All Ks and Ss are non‐negative, and Cs are physically constrained to be between 0 and 1. Standard estimation procedures cast the Kubelka–Munk relationships as an overdetermined linear system and apply ordinary least squares (OLS). OLS, however, sometimes produces coefficients or concentrations that are less than 0 or greater than 1. These physically impossible solutions occur because OLS projects a target vector (such as a desired reflectance spectrum) onto a vector subspace, while in fact the set of physically realisable paint combinations is a convex polytope, which is a subset of that subspace. This paper reformulates Kubelka–Munk estimation problems geometrically, as the problem of finding the point on that polytope which is closest to a target vector. The solutions to the reformulated problem are always physically realisable. If feasible, a worker could solve the reformulated problem with a ready‐made commercial solver. Otherwise, the Gilbert–Johnson–Keerthi algorithm is recommended as particularly suitable for Kubelka–Munk estimation; this algorithm has been tested on some simple cases and released as open‐source code.

The altar wall paintings of the catholicon "The Nativity of the Virgin", Rila Monastery, Bulgaria: Identification of the painting materials by means of vibrational spectroscopic techniques complemented by EDX, XRD and TGA analysis.

The purpose of the present study is to deepen our knowledge about the painting materials and technology characteristics of iconography during the Bulgarian National Revival. Our efforts have focused on studying the murals in the catholicon (main church) "The Nativity of the Virgin" of the Rila Monastery, which is one of Bulgarian leading historical monuments. A series of micro samples from the altar mural paintings were analyzed by a combination of attenuated total reflectance Fourier transform infrared (ATR-FTIR), micro-Raman spectroscopy, scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Optical microscopy (OM). The data analysis showed that the painter's palette is made up of nine mineral pigments: smalt, chrome yellow, emerald green, vermilion, red lead, green earths, yellow ochre, sienna and calcite. The impression of rich colorful palette was achieved by using various pigment mixtures. The presence of egg binder in many paint samples suggested that the murals were executed by the traditional egg tempera technique, with the only exception of the smalt paint of the background where carbohydrate glue is present as binder.

Manufacture and characterization of a 3D-printed integrating sphere

3D printers are more accessible in both academic and research groups, becoming instruments to facilitate the construction of high-quality scientific equipment for laboratories. In the present study, a 3D printed integrating sphere was validated to acquire diffuse reflectance and transmittance on turbid samples in order to compute optical absorption and reduced scattering through the inverse adding doubling algorithm. The 3D printed integrating sphere was validated in three stages: analysis of the integrating sphere coating reflectance using two possible coating materials (barium sulfate powder and a mixture of barium sulfate and paint), the sphere wall reflectance, and using two accurate optical polyurethane phantoms to measure the absorption and reduced scattering coefficients. The results indicate that the system developed with this methodology shows satisfactory reflectance compared to commercial models and is able to acquire experimental diffuse reflectance and transmittance measurements to compute the optical coefficients of turbid samples due to the use of an inverse adding doubling (IAD) algorithm. However, this system is limited to the region from 500 to 1300 nm due to a decrease in the reflectance of the coating.

Digital inkjet printing in three dimensions with multiple ceramic compositions

Compared to metals and polymers, the poor processability of ceramic materials limits their use in industrial applications, despite their excellent properties. Three-dimensional (3D) printing methods can increase the processing flexibility of ceramic materials. Here, we report inkjet-based 3D printing process with different ceramic compositions. Ultraviolet (UV) curable ceramic ink was synthesized from a mixture of ceramic pigments, UV curable monomer, dispersant, and photoinitiator. The rheological properties and jetting behavior of ceramic ink were optimized. The influences of the photoinitiator and contact angle on the additive printing behavior were also investigated in detail. Finally, the 3D objects which consist of multiple ceramic materials and compositional gradients were successfully formed using inkjet printing.

The role of smalt in complex pigment mixtures in Rembrandt\u2019s Homer 1663: combining MA-XRF imaging, microanalysis, paint reconstructions and OCT

As part of the NWO Science4Arts REVISRembrandt project (2012–2018), novel chemical imaging techniques were developed and applied to the study of Rembrandt’s late experimental painting technique (1651–1669). One of the unique features in his late paintings is his abundant use of smalt: a blue cobalt glass pigment that he often combined with organic lake pigments, earth pigments and blacks. Since most of these smalt-containing paints have discolored over time, we wanted to find out more about how these paintings may have originally looked, and what the role of smalt was in his paint. This paper reports on the use of smalt in complex pigment mixtures in Rembrandt’s Homer (1663), Mauritshuis, The Hague. Macroscopic X-ray fluorescence imaging (MA-XRF) assisted by computational analysis, in combination with SEM-EDX analysis of paint cross-sections, provides new information about the distribution and composition of the smalt paints in the painting. Paint reconstructions were carried out to investigate the effect of different percentages of smalt on the overall color, the drying properties, translucency and texture of the paint. Results show that the influence of (the originally blue) smalt on the intended color of the paint of the Homer is minimal. However, in mixtures with high percentages of smalt, or when combined with more transparent pigments, it was concluded that the smalt did produce a cooler and darker paint. It was also found that the admixture of opaque pigments reduced the translucent character of the smalt. The drying tests show that the paints with (cobalt-containing) smalt dried five times faster compared to those with glass (without cobalt). Most significantly, the texture of the paint was strongly influenced by adding smalt, creating a more irregular surface topography with clearly pronounced brushstrokes. Optical coherence tomography (OCT) was used as an additional tool to reveal differences in translucency and texture between the different paint reconstructions. In conclusion, this study confirmed earlier assumptions that Rembrandt used substantial amounts of smalt in his late paintings, not for its blue color, but to give volume and texture to his paints, to deepen their colors and to make them dry faster.

La Aproximación histórica al arte rupestre prehispánico de la sierra de El Alto-Ancasti (provincia de Catamarca, noroeste argentino)

How can we approach the process through which rock art panels have been built and modified? How to connect these histories of painting/engraving with the others social practices performed in the caves though the time? The goal of this article is to remark the importance of these questions and describe a methodology intended to solve them through the combination of multiple levels of analysis, with five different lines of evidence (spatial analysis, overlapping studies, morphologic-stylistic studies, analysis of pigment mixtures and the stratigraphic excavation of the floor’s sediments). As an example, we present the results obtained by the application of this methodology to the study of the rock art from El Alto-Ancasti’s Sierra; however the methods and techniques could be useful for the research of other sites.

Concentrations and size distribution of TiO2 and Ag engineered particles in five wastewater treatment plants in the United States

The growing use of engineered particles (e.g., nanosized and pigment sized particles, 1 to 100 nm and 100 to 300 nm, respectively) in a variety of consumer products increases the likelihood of their release into the environment. Wastewater treatment plants (WWTPs) are important pathways of introduction of engineered particles to the aquatic systems. This study reports the concentrations, removal efficiencies, and particle size distributions of Ag and TiO2 engineered particles in five WWTPs in three states in the United States. The concentration of Ag engineered particles was quantified as the total Ag concentration, whereas the concentration of TiO2 engineered particles was quantified using mass-balance calculations and shifts in the elemental ratio of Ti/Nb above their natural background elemental ratio. Ratios of Ti/Nb in all WWTP influents, activated sludges, and effluents were 2–12 times higher (e.g., 519 to 3243) than the natural background Ti/Nb ratio (e.g., 267 ± 9), indicating that 49–92% of Ti originates from anthropogenic sources. The concentration of TiO2 engineered particles (in μg TiO2 L−1) in the influent, activated sludge, and effluent varied within the ranges of 70–670, 3570–6700, and 7–30, respectively. The concentration of Ag engineered particles (in μg Ag L−1) in the influent, activated sludge, and effluent varied within the ranges of 0.11–0.33, 1.45–1.65, and 0.01–0.04, respectively. The overall removal efficiency (e.g., effluent/influent concentrations) of TiO2 engineered particles (e.g., 90 to 96%) was higher than that for Ag engineered particles (e.g., 82 to 95%). Particles entering WWTPs are in the nanosized range for Ag (e.g., >99%) and a mixture of nanosized (e.g., 15 to 90%) and pigment sized particles (e.g., 10 to 85%) for TiO2. Nearly all Ag (>99%) and 55 to 100% of TiO2 particles discharged to surface water with WWTP effluent are within the nanosize range. This study provides evidence that TiO2 and Ag engineered nanomaterials enter aquatic systems with WWTP effluents, and that their concentrations are expected to increase with the increased applications of TiO2 and Ag engineered nanomaterials in consumer products.

An alternative approach to mapping pigments in paintings with hyperspectral reflectance image cubes using artificial intelligence

Spectral imaging modalities, including reflectance and X-ray fluorescence, play an important role in conservation science. In reflectance hyperspectral imaging, the data are classified into areas having similar spectra and turned into labeled pigment maps using spectral features and fusing with other information. Direct classification and labeling remain challenging because many paints are intimate pigment mixtures that require a non-linear unmixing model for a robust solution. Neural networks have been successful in modeling non-linear mixtures in remote sensing with large training datasets. For paintings, however, existing spectral databases are small and do not encompass the diversity encountered. Given that painting practices are relatively consistent within schools of artistic practices, we tested the suitability of using reflectance spectra from a subgroup of well-characterized paintings to build a large database to train a one-dimensional (spectral) convolutional neural network. The labeled pigment maps produced were found to be robust within similar styles of paintings.

Improving the trays solar still performance using reflectors and phase change material with nanoparticles

Abstract The potable water shortage is a big problem facing the governments and decision-makers everywhere. Solar distiller is one of the techniques that participate in solving this problem. In this work, the impact of internal reflectors on the trays distiller performance was investigated. Besides, the influence of painting the surfaces of the solar still by the mixture of black paint and copper oxide (CuO) nanoparticles was studied. This is to enhance the heat transfer characteristics between the basin surfaces and water. Finally, the impact of using the paraffin wax mixed with CuO nanoparticles as a phase change material (PCM) on the performance of trays distiller was evaluated. Experimental results revealed that the total freshwater yield of the trays distiller was improved by 57, 14, 70.7, and 108% when using reflectors, CuO nanoparticles in paint, reflectors and nano-coating, and the collection of reflectors, nano coating, and PCM with CuO nanoparticles respectively over that of the reference still. Also, the total accumulated freshwater of the conventional and trays solar stills reached 2400 and 5000 mL/m² a day, respectively. Moreover, the thermal efficiency of the trays distiller with reflectors, nano-paint coating, and PCM-CuO nanoparticles mixture was 51.5%.

The colours of Rome in the walls of C\xe1stulo (Linares, Spain)

Wall paintings have become one of the most relevant, complex and challenging research subjects in Archaeometry. Minimally- or non-invasive, accurate and multidisciplinary methods are needed to successfully address the problems posed by their physical and chemical properties and by their analysis techniques. Specifically, the analytical method implemented for the study of this type of samples must enable a precise separation of the chemical information from backgrounds and scenes, allowing the identification of pigment’s components in overlapping layers, the detection of minority components and the elucidation of pigment mixtures. Thus, this paper puts forward a multidisciplinary approach towards these goals by means of the combined use of micro Energy Dispersive X-ray Fluorescence (µEDXRF) surface mapping and single-spot micro-Raman spectroscopy and µEDXRF analysis. The samples under research come from the site of Cástulo (Linares, Spain), one of the most important Roman cities in the Iberian Peninsula. It must be emphasized the uniqueness of the walls of Cástulo, their optimal conservation state and the richness and variety of the colour’s palette used in their decoration, which make them an excellent and representative example of Roman wall paintings.

Mixture design experiments applied for the formulation of a textile ink with reproduction of the NATO IRR green color used in military camouflage

This paper presents the development of a mathematical model for pigment formulations used for screen printing textile inks in order to reproduce the NATO IRR green standard using four highly performant pigments: Hostaperm Yellow H4G (CI 13980), Irgazin Red A2BN (CI 65300), Heliogen Blue (CI 74160), and Lamp Black (CI 77266). In order to study the influence of each pigment on the final CIE L* a* b* parameters, a quadratic mathematical model (Scheffé type) was created and experimentally validated. The model was used and verified for generating pigment compositions for textile inks that reproduce the NATO IRR green. A total of 22 possible solutions were developed and experimentally performed. Studies regarding the reflectance in the visible-near-infrared domain were conducted, ensuring compliance with the standard. The optimal composition of the pigment mixture was 66.55% Hostaperm Yellow H4G, 7.66% Heliogen Blue, 12.01% Irgazin Red A2BN, and 13.78% Irgazin Red A2BN. The mixture was added to textile ink in the proportion of 5% and was applied via serigraphy.

Investigating the potential use of polymeric materials in the preparation of temporary cosmetic teeth painting veneers

Dental whitening techniques and materials have become one of the most important non-surgical methods used to improve the appearance of teeth and to make them whiter and brighter, as well as to hide blemishes of the teeth. Since the veneer do not last forever and may fail due to fracture or adhesion failure or wrong selection of the appropriate design, removing large thickness of the outer layer of the tooth may make it vulnerable to weakness and long-term failure. This study aims to reach the polymeric combination that enables us to prepare temporary cosmetic teeth painting veneers, and to improve their properties, in order to get the veneers that work to maintain as much tooth structure as possible, hide defects and beautify teeth in the easiest ways and at least costs. The results showed that it is possible to prepare a paint mixture based on cheap and available raw materials consisting of sodium alginate as a polymeric matrix material in this mixture, titanium dioxide as a coloring additive, and calcium chloride solution as a bonding for sodium alginate molecules and improving for their properties. It is recommended to use the fourth combination (sodium alginate 2% + titanium dioxide 4%) immersed in a solution of calcium chloride (11.11% concentration) in the preparation of temporary paints due to its highest chemical stability and having appropriate physical and optical properties that enable them to use possibly as temporary cosmetic teeth painting veneers.

Looking for paint mixtures to glimpse pictorial techniques: a micro-stratigraphic physicochemical approach to the rock art from the Oyola\u2019s Caves (Argentina)

Could not be possible that rock paintings with similar hues and morphologies were the result of different paint preparations inside a cave but distanced in time? Is there any archaeometric approach that allow us to evidence these subtle differences? Aiming to address these inquires, in this work are presented the potentials of new physicochemical lines of evidence for characterization and differentiation of paint mixtures. This will improve the understanding of the technical heterogeneity and temporal complexity of painting sets executed in a particular archaeological site. In order to explore these points, the results obtained in the micro-stratigraphic studies of samples taken from the painted walls of Oyola, an archaeological site located in the northwest of Argentina, are presented. These samples have been analyzed by micro-Raman spectroscopy (mRS) and scanning electron microscopy with energy dispersive X-ray (SEM–EDS). The differences found by cross-section chemical studies could be explained as a consequence of two situations: 1-differences in the painting’s chemical components, either in the pigments involved or additives used; and, 2-differences in the physical properties of the mixtures such as stratum thickness and/or particle size. Also, in this article are explained each of the hypothesis, presenting the limits of these interpretations and pointing out future research challenges. As we discussed, it could be possible that the chemical and physical differences found between paint mixtures were the material expression of varied types of pictorial techniques.

The effects of water-based insulation paint applied to laminate flooring panels on the thermal conductivity coefficient and adhesion resistance

In an effort to reduce negative feedback resulting from temperature fluctuations, house floors are commonly laid with laminate flooring. The aim of this study was to study the thermal insulation properties and adhesion strength of the water-based insulation paint mixed with hollow glass spheres and applied onto the laminate flooring. The objective was to determine whether a prepared insulation paint mixture can be used instead of backing paper. For this purpose, two different laminate flooring samples were used. In the first case, the upper surface of the sample was coated with decorative paper and the lining surface was coated with backing paper. The upper surface of the second sample was coated with decorative paper and the lining surface was not coated with backing paper. Then, insulation paint mixture was applied 2, 4, or 6 times to the lining surfaces of both groups, and experimental results were obtained. As the number of layers was increased, the insulation mixture applied to the lining surfaces of the test samples was found to contribute positively to thermal insulation and adhesion resistance of specimens.

Scagliola Interiors in Vienna 1800–1900: Material, Development and Conservation

ABSTRACT In the Central European context the imitation of natural stone is called stucco marble or scagliola. During its manufacture, the mixture of gypsum, animal glue and pigments produces a marble-like structure and after several sanding and polishing processes it attains a glossy surface. Scagliola plays a significant role in the history of interior design in the eighteenth and nineteenth centuries in central Europe. Originally, it was used during the first half of the seventeenth century to imitate stone inlaid work, pietra dura, for table tops and as antependia. Scagliola interiors in the eighteenth century, the main period of use, have individual designs, colours and shapes. This technique was substituted for stone because coloured marble was expensive, and some types of natural stone have a limited colour range. In the first half of the nineteenth century, scagliola found little or no application, but it was rediscovered in the second half of the century. In Vienna, high-quality stucco marble was used extensively in public buildings or private palaces. Recent research is focusing on the interior of churches during the Baroque and Rococo periods in southern Germany. Studies on conservation methods for scagliola barely exist at an international level. In order to ensure the preservation of these valuable surfaces, a catalogue is being compiled of nineteenth-century scagliola works in Vienna, as well as an overview of recent and present conservation measures.

Effect of a SO2 Rich Atmosphere on Tempera Paint Mock-Ups. Part 2: Accelerated Aging of Azurite- and Malachite-Based Paints

In order to improve our knowledge of the weathering response of tempera paints exposed to an industrial atmosphere, azurite- and malachite-based paint mock-ups prepared with either rabbit glue or egg yolk binders were artificially aged in an SO2 rich atmosphere. The aim was to identify the different alteration mechanisms and forms of degradation in the paints by observing their physical (color, gloss, reflectance, and roughness), mineralogical, chemical, and micro-textural characteristics. Superficial physical changes were evaluated by stereomicroscopy, spectrophotometry, gloss measurement, hyperspectral imaging, and roughness measurements. Chemical and mineralogical changes were evaluated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy with microanalysis (SEM-EDS), which was also used to evaluate the micro-texture of the paints. The differences between the fresh temperas were due mainly to the binder (egg yolk or rabbit glue) used in the paint mixture, which also played a crucial role in the different deterioration patterns in the artificially aged paint mock-ups. Thus, the egg yolk-based paints remained physically quite intact after SO2 exposure, although they suffered more significant chemical degradation, above all in the form of copious precipitation of Cu and Ca-rich sulfate salts and the subsequent yellowing of the egg yolk binder. The SO2 aged rabbit glue-based mock-ups showed microscopically important crack formation and binder loss and fewer sulfated salts precipitated on the surface of the paints.

Modification of Gunung Kidul Natural Zeolite and Its Application in the Corrosion Rate Reduction of Steel Plates in Acid Media

The use of metals in the industry plays a very important role, where nearly 90% of industrial equipment comes from metallic materials. Corrosion is an electrochemical process between metals with its environment that can damage the metal quality. Gunung Kidul natural zeolite can be modified into a mixture of alkyd paint as a coating material to reduce the corrosion rate of steel plates effectively. In this research, the zeolite was activated by NaOH 1 N for 120 minutes. The zeolite was characterised using Surface Area Analyzer (SAA) and nitrogen adsorption analysis to investigate the surface area of zeolite by Brunauer-Emmet-Teller (BET) modelling. The lining was done by coating the steel plates by alkyd-zeolite paints and inserted into a 100 mL H2SO4 1N, 2N, and 3N for 20 days. The results of this study showed that the corrosion rate of steel plate was 0.1374 miles/year (uncoated), 0.0407 miles/year (coated by alkyd paint), and 0.0095 miles/year (coated by alkyd paint-zeolite). Using activated zeolite as a mixture of alkyd paint is environmentally friendly and effective in lowering the corrosion rate of mild steel plates.