Pigment Crystals Research Articles

Multidisciplinary approach to the study of large-format oil paintings

Cultural heritage has become a keystone for comprehending our society, as it represents and reflects our origins, passions, beliefs and traditions. Furthermore, it provides fundamental information about specific temporary spaces, materials’ availability, technology, artist’s intention, and site weather conditions. Our aim was to develop a multidisciplinary approach with a main focus on investigating two Italian large-format paintings located in highly diverse environments such as the National Theater of Costa Rica. We monitored environmental conditions and quantified fungal aerial spores. Then, we determined regions of possible biodeterioration with the software MicroorganismPattern and used the software PigmentArrangement to elucidate the apparent colour of the paintings based on distribution and arrangement of the pigment crystals. Finally, we characterized eight genera of calcareous nannofossils found in the ground layers of the artwork. The former Men’s Canteen at the National Theater of Costa Rica presented a mean air temperature of 23.5 ^{circ }C, a relative humidity of 72.7% and a concentration of CO_{2} of 570 ppm. The fungal aerial concentration was 1776 spores/m^{3}. The software MicroorganismPattern identified 32 sampling regions, out of which 11 were positive for microbial contamination. The software PigmentArrangement determined that the blue crystals (ultramarine pigment) had the shortest distances between themselves (29 upmum). Finally, the nanofossils identified enabled us to restrict the age of the material to a biostratigraphic interval ranging from Coniacian to Maastricthian ages. By using a multidisciplinary approach we were able to explore the diptych, suggest a set of minimally invasive perspectives in tropical environments to be used worldwide and obtain key information about the artist’s artistic process, materials used along with better understand its state of conservation.

Securely anchored Prussian blue nanocrystals on the surface of porous PAAm sphere for high and selective cesium removal

Prussian blue (PB) has been well known as a pigment crystal to selectively sequestrate the radioactive cesium ion released from aqueous solutions owing to PB cage size similar to the cesium ion. Because the small size of PB is hard to deal with, the adsorbents containing PB have been prepared in the form of composites causing low sequestration efficiency of cesium. In this study, securely anchored PB nanocrystals on the surface of millimeter-sized porous polyacrylamide (PAAm) spheres (PB@PAAm) have been prepared by the crystallization of PB on the Fe3+ adsorbed PAAm. The securely anchored PB nanocrystals have been demonstrated to be selective and efficient adsorbents for sequestration of the radioactive cesium. The well-interconnected-spherical pores and millimeter-sized diameter of the PB@PAAm adsorbents facilitated permeation of Cs+ into the adsorbent and ease of handling respectively. Especially the well-interconnected-spherical pores allowed that PB@PAAm showed 90% of its maximum Cs+ adsorption capacity within 30 min. The PB@PAAm showed an outstanding Cs+ capture ability of 374 mg/g, high removal efficiency of 85% even at low concentration of Cs+ (10 ng/L), and superior selectivity of Cs+ against interference ions of Na+, K+, Mg2+, and Ca2+.

Revealing time\u2019s secrets at the National Theatre of Costa Rica via innovative software for cultural heritage research

Establishing affordable, efficient, accessible, innovative, and multidisciplinary methodologies to the diagnosis of the conservation state of an artwork is key to carry out appropriate strategies of conservation and consequently to the creation of modern public policies on cultural heritage. Limited access to large-format paintings is a challenge to restoration scientists seeking to obtain information quickly, in a non-destructive and non-invasive manner, and identify regions of interest. Therefore, we put forward two unique software tools based on multispectral imaging techniques, with the long-term aim to assess the artist’s intentions, creative process, and colour palette. This development paves the way for a comprehensive and multidisciplinary understanding of the mysteries encompassed in each pictorial layer, through the study of their physical and chemical characteristics. We conducted the first ever study on Musas I and Musas II, two large-format paintings by Italian artist Carlo Ferrario, located in the National Theatre of Costa Rica. In this study, we used our novel imaging techniques to choose regions of interest in order to study sample layers; while also assessing the works’ state of conservation and possible biodeterioration. We explored the applications of our two versatile software tools, RegionOfInterest and CrystalDistribution, and confirmed paint stratigraphies by means of microscopy and spectroscopy analyses (OM, SEM-EDX, Fluorescent microscopy, FTIR-ATR and micro-Raman). In a pilot study, we identified the artist’s main colour palette: zinc white, lead white, chrome yellow, lead read, viridian, along with artificial vermilion and ultramarine pigments. We were able to identify artificial vermilion and ultramarine and distinguish them from the natural pigments using CrystalDistribution to map the average size and diameter of the pigment crystals within the paint layers. This study demonstrated that software-based multidisciplinary imaging techniques are novel in establishing preventive and non-invasive methods for historical painting conservation studies, in addition, this study provides tools with great potential to be used in the future in applications such as virtual restoration.

Optimization of laser technology for removing tatuage pigment

Purpose: To study the effectiveness of tattoo pigment removal with laser light depending on the wavelength and depth of penetration into tissues in order to optimize a technique of laser selective photocavitation. Material and methods. 127 male white mongrel rats, aged 8 weeks, were intradermally injected with pigment particles into their backs looking like 2 rows of spots 0.5 cm in diameter. In 6 weeks, 367 skin samples with tattoo pigment were taken. Each sample was a patch of epidermis with pigment crystals surrounded by connective tissue capsules not less than 2.5 mm of thickness. Before the experiment, the epidermal stratum corneum – 10–15 mkm in depth and about 1 mm in diameter- was removed with spray-coagulation (apparatus EHVCH-50-MEDSI). The rest of skin flap surface remained intact. Thus, each skin sample had two areas on the surface – one with removed stratum corneum (experimental) and the other one intact (control). To register changes in the luminous flux, the authors placed an emitter (IPL xenon lamp 7.65.130), tissue sample and photomultiplier (PMT-62) on one and the same axis. To cut off light waves, the authors used a set of light filters – 315, 364, 400, 440, 490, 540, 590, 670, 750, 870, 980 nm. Results. Destruction of skin surface layers was not statistically significant under wavelengths up to 450 nm and after 1000 nm. The epidermal stratum corneum prevents laser light penetration with wavelengths 450–694 nm by 27%, in average, and with wavelengths 700–1000 nm by 33%, in average. Conclusion. Epidermal stratum corneum destruction statistically significantly increases light density in deep tissue layers and increases the depth of penetration of laser light into biological tissues.

Oil-Based Fungal Pigment from Scytalidium cuboideum as a Textile Dye.

Identification of effective natural dyes with the potential for low environmental impact has been a recent focus of the textile industry. Pigments derived from spalting fungi have previously shown promise as textile dyes; however, their use has required numerous organic solvents with human health implications. This research explored the possibility of using linseed oil as a carrier for the pigment from Scytalidium cuboideum as a textile dye. Colored linseed oil effectively dyed a range of fabrics, with natural fibers showing better coloration. Scanning electron microscopy (SEM) revealed a pigment film over the fabric surface. While mechanical testing showed no strength loss in treated fabric, colorfastness tests showed significant changes in color in response to laundering and bleach exposure with variable effects across fabric varieties. SEM investigation confirmed differences in pigmented oil layer loss and showed variation in pigment crystal formation between fabric varieties. Heating of the pigmented oil layer was found to result in a bright, shiny fabric surface, which may have potential for naturally weatherproof garments.

Scientific analysis of some glazed pottery unearthed from Warring States Chu tombs in Jiangling, Hubei Province: Indication for the origin of the low‐fired glazed pottery in China

A portable energy dispersive X‐ray fluorescence spectrometer and a micro‐Raman spectrometer are used for the nondestructive analysis of a batch of glazed pottery ornaments unearthed from Warring States Chu (楚) tombs (B.C.475–B.C.221) in Jiangling, Hubei Province, China. According to the chemical compositions obtained, all of the glazes belong to the lead–barium–silicate (PbO–BaO–SiO2) system and contain certain levels of copper. The man‐made barium copper silicate pigment crystals, such as Chinese blue (BaCuSi4O10) and Chinese purple (BaCuSi2O6), are identified from several samples by micro‐Raman spectrometer. Besides, gypsum and hematite are found in the white and brown regions of two eye beads. Combined with other glazed pottery and the related silicate artifacts (e.g., lead–barium glass and faience, potash–lime glass and glazed pottery, high‐lead glazed pottery, etc.), the origin, development, and affected factors of ancient Chinese low‐fired glazed pottery have been discussed preliminarily. The present study provides principal evidences for the technological provenance, raw material recipes, and the relationship between low‐fired glazed pottery and related vitreous materials of ancient China. It also provides some significant clues for the origin and the development of ancient Chinese lead–barium glass.

Efficient monitoring of the blood-stage infection in a malaria rodent model by the rotating-crystal magneto-optical method.

Intense research efforts have been focused on the improvement of the efficiency and sensitivity of malaria diagnostics, especially in resource-limited settings for the detection of asymptomatic infections. Our recently developed magneto-optical (MO) method allows the accurate quantification of malaria pigment crystals (hemozoin) in blood by their magnetically induced rotation. First evaluations of the method using β-hematin crystals and in vitro P. falciparum cultures implied its potential for high-sensitivity malaria diagnosis. To further investigate this potential, here we study the performance of the method in monitoring the in vivo onset and progression of the blood-stage infection in a rodent malaria model. Our results show that the MO method can detect the first generation of intraerythrocytic P. berghei parasites 66–76 hours after sporozoite injection, demonstrating similar sensitivity to Giesma-stained light microscopy and exceeding that of flow cytometric techniques. Magneto-optical measurements performed during and after the treatment of P. berghei infections revealed that both the follow up under treatment and the detection of later reinfections are feasible with this new technique. The present study demonstrates that the MO method – besides being label and reagent-free, automated and rapid – has a high in vivo sensitivity and is ready for in-field evaluation.

Prussian blue (PB) granules for cesium (Cs) removal from drinking water

Cesium (Cs) removal from tap water has become an emerging issue after the disaster at the Fukushima Daiichi Nuclear Power Plant. Prussian blue (PB), a pigment crystal with a cage size similar to the hydration radius of Cs+, is used in this study for the first time to remove Cs from drinking water. Adsorption isotherms of Cs on PB granules, which were determined at room temperature, fit Langmuir equations. The Cs-PB affinity was high, tolerating the challenge from competing ions and hypochlorite. Column tests and simulated rapid sand filter tests indicate that PB granules are highly efficient Cs adsorbents with low water head loss during applications. Possible scenarios for using PB granules as a Cs barrier in waterworks were discussed.

Malaria pigment crystals as magnetic micro-rotors: key for high-sensitivity diagnosis

The need to develop new methods for the high-sensitivity diagnosis of malaria has initiated a global activity in medical and interdisciplinary sciences. Most of the diverse variety of emerging techniques are based on research-grade instruments, sophisticated reagent-based assays or rely on expertise. Here, we suggest an alternative optical methodology with an easy-to-use and cost-effective instrumentation based on unique properties of malaria pigment reported previously and determined quantitatively in the present study. Malaria pigment, also called hemozoin, is an insoluble microcrystalline form of heme. These crystallites show remarkable magnetic and optical anisotropy distinctly from any other components of blood. As a consequence, they can simultaneously act as magnetically driven micro-rotors and spinning polarizers in suspensions. These properties can gain importance not only in malaria diagnosis and therapies, where hemozoin is considered as drug target or immune modulator, but also in the magnetic manipulation of cells and tissues on the microscopic scale.

Structure and Formation of Synthetic Hemozoin: Insights From First-Principles Calculations

Malaria, an infectious disease once considered eradicated, has reemerged in recent years, primarily due to parasite resistance to commonly used synthetic antimalarial drugs. These drugs act by inhibiting crystallization of the malaria pigment, hemozoin (HZ). Thus, there is a vital need for understanding the process of HZ nucleation. In a companion paper, the pseudopolymorphic behavior of β-hematin, the synthetic form of HZ, has been characterized by X-ray diffraction (XRD) (Straaso, T.; Kapishnikov, S.; Kato, K.; Takata, M.; Als-Nielsen, J.; Leiserowitz, L.Cryst. Growth Des. 2011, 11, DOI: 10.1021/cg200410b). Here, we employ van der Waals (vdW)-corrected density functional theory (DFT) to study the two β-hematin crystal structures and their repeat unit, a heme dimer. We find that vdW interactions play a major role in the binding of the heme dimer and the β-hematin crystal. In addition, accounting for the periodic nature of the system is essential to obtaining the correct geometry of the heme dimer, which ...

Herpothallon rubroechinatum (Arthoniaceae), a new species from tropical and subtropical America

Herpothallon rubroechinatum is described from the U.S.A. (Florida), Costa Rica and Peru. The new species is characterised by scattered red anthraquinone crystals being attached to hyphae projecting from the thallus, the globose to cylindrical pseudoisidia, a closely adnate thallus, and psoromic acid as the main lichen compound; pycnidia are common at the tips of the pseudoisidia. The medulla of the new species shows a patchily distributed amyloid reaction. Contrary to previous reports, the amyloidity of the medulla was observed in all Herpothallon species re-investigated during this study. H. rubroechinatum is compared to the two other red pigmented species that contain psoromic acid, H. australasicum that lacks pigment crystals on the pseudoisidia, and H. globosum that has a loosely attached thallus and a well developed red hypothallus.

Study on Coating and Luminescence Mechanism of Hydrothermal Preparation of Mica-based Pearlescent Pigments

Pearlescent pigment with the properties of high crystallinity, good dispersity, no agglomeration and smooth and crackless surface was prepared by hydrothermal method instead of calcination in the present paper. Through observation, rules of preparing high performance pearlescent pigment were obtained, described as follows: Increment of temperature and elongation of time during the period of hydrothermal reaction was beneficial to the crystallization of pearlescent pigment. Herein, coating and luminescence mechanism of pearlescent pigment was taken into further investigation.

Modern tattoos cause high concentrations of hazardous pigments in skin

Modern tattoo colourants frequently consist of azo pigments that not only contain multiple impurities but also are originally produced for car paint and the dyeing of consumer goods. In order to be able to assess the health risk of tattoos, it is important to determine the pigment concentration in human skin. We tattooed excised pigskin and human skin with a common tattoo pigment (Pigment Red 22) under various conditions. After tattooing, we quantitatively extracted the pigment in order to determine the pigment concentration in skin. The concentration of pigments ranged from about 0.60 to 9.42 mg/cm(2) of tattooed skin (mean value 2.53 mg/cm(2)) depending upon the size of the pigment crystals, the pigment concentration applied to the skin surface, and the respective procedure of tattooing. In conclusion, high concentrations of colourants are injected into the skin during tattooing and based upon this quantification, a risk assessment of tattooing ought to be carried out.

Preparation of waterborne nanoscale pigment dispersions for formulations of inkjet inks

Textiles Inkjet printing as a new dyeing method with higher resolution, lower pollution and shorter run length has attracted more and more people's attention. Pigment inks have become one of the main colorant materials in this technology for its excellent light fastness and suitable to all sorts of textiles. However most of organic pigments with low polarity are hard to be wetted and dispersed in aqueous media, therefore the organic pigments should be modified before their application. In this paper, waterborne nanoscale pigment dispersion including Copper Phthalocyanine blue (P.B.15:3), Quinacridone red pigment (P.R.122), and Monoazo yellow pigment (P.Y.14) have been prepared by phase separation method and direct milling with dispersants method respectively. The properties (stability, particle size and apparent viscosity) of dispersion which prepared by different method were compared. The results show that the pigment dispersion has higher stability to alcohols, temperature and storage, and also lower viscosity; the phase separation method was more suitable to preparation of pigment dispersion for formulations of inkjet inks than direct milling with dispersants method; TEM photo indicated that the pigment particles were uniformly distributed in aqueous media and the XRD curves indicated that the pigment crystal was not changed after encapsulation by phase separation method.

The Use of an Exact Light‐Scattering Theory for Spheroidal TiO2 Pigment Particles

Titanium dioxide pigments are widely used, e.g., in paints, printing inks, plastics, and papers, because of the excellent and whiteness they provide. As is well known, the opacity and to it related optical properties depend on the pigment's crystal- and particle-size distributions (CSD, PSD). Therefore, the process and quality control of the CSD and PSD are very essential. The development of a straightforward and sophisticated method for process and quality control is presented here. The principal component is a new determination method for the PSD based on an accurate theory of light scattering of spheroidal particles. In this new method, called the turbidity spectrum method (TSM), the whole turbidity spectrum is measured. This spectrum, which is due to the particle-size distribution of the pigment particles, is then solved using the T-matrix method by taking into account the shape of the particles. After that the CSD is extracted from the PSD. The T-matrix method is one of the most powerful and widely used tools for the rigorous computing of electromagnetic scattering by non-spherical particles. The repeatability of the mean PSD (∼200 nm) obtained by the TSM is excellent, with a standard deviation of 0.1 nm (0.05 %). Linear regression models based on TSM results were developed for undertone and tint-reducing power, which are important optical parameters of the pigment. The excellent repeatability of the TSM results was necessary for the production of representative models.

Hemozoin formation in Echinostoma trivolvis rediae

Rediae of the trematode Echinostoma trivolvis, from naturally infected Helisoma trivolvis snails, form a black pigment while inside the snail host. Here we examine the black pigment to show that the insolubility characteristics in detergent and weak base solution are identical to Plasmodium falciparum hemozoin. Laser desorption mass spectrometry of the purified pigment demonstrates the presence of heme. Examination of purified pigment under polarized light microscopy illuminates ordered birefringent crystals. Field emission in lens scanning electron microscopy reveals irregular ovoid crystals of 200–300 nm in diameter. The purified pigment crystals seeded extension of monomeric heme onto the crystal which by Fourier Transform Infrared analysis is β-hematin. Rediae of a second echinostome parasite, Echinostoma caproni, from experimentally infected Biomphalaria glabrata, do not produce measurable or recoverable heme crystals. These observations are consistent with heme crystal formation by a hematophagous parasite within a non-vertebrate intermediate host.

Production and characterisation of iron-chromium pigments and their interactions with transparent glazes

Abstract In this study, production and characterisation of pigments by using less expensive raw materials such as limonite and chromite was undertaken. The resulting pigments were characterised by using X-ray diffraction (XRD) and UV-Vis spectrophotometer. The colour of glazed tiles containing 3 wt.% pigment change from dark brown to light brown depending on the calcination temperature and limonite content. With pigments prepared with 50% limonite content calcined at 1250 °C, the chocolate brown colour was obtained corresponding to the commercial brown pigments. An iron-chromium black pigment was synthesised from a mixture of pure chromium (III) oxide (Cr 2 O 3 ) and iron (III) oxide (Fe 2 O 3 ) powders and was used to determine possible interactions between a pigment and a transparent glaze. The interactions were studied using a scanning electron microscope (SEM) attached with an energy dispersive X-ray spectrometer (EDX). The results showed that black pigment particles give brown colour to the glaze. EDX analysis on pigment crystals embedded in the glaze clearly showed that Zn and Mg diffused into pigment crystals and caused a change of colour from black to brown.

The production, purification and crystallization of a pocilloporin pigment from a reef-forming coral.

Reef-building corals contain fluorescent pigments termed pocilloporins that function by regulating the light environment of coral and acting as a photoprotectant in excessive sunlight. These pocilloporins are related to the monomeric green fluorescent protein and the tetrameric DsRed fluorescent proteins, which have widespread use as biotechnological tools. An intensely blue-coloured pocilloporin, termed Rtms5, was expressed in Escherichia coli, purified and crystallized. Rtms5 was shown to be tetrameric, with deep blue crystals that diffract to 2.2 A resolution and belong to space group I4(1)22. The colour of this pocilloporin was observed to be sensitive to pH and a yellow (pH 3.5) and a red form (pH 4.5) of Rtms5 were also crystallized. These crystals belong to space group P4(2)22 and diffract to 2.4 A resolution or better.

Isolation of Plasmodium berghei ookinetes in culture using Nycodenz density gradient columns and magnetic isolation

BackgroundLarge scale in vitro production of the mosquito stages of malaria parasites remains elusive, with only limited success for complete sporogonic development and only one report of development through to infective sporozoites. The initial step in this process is the production, in vitro, of ookinetes from gametocytaemic blood. Methods for isolation of these ookinetes from blood cells have been described; however, in addition to yield often being low, processing time and potential for contamination by erythrocytes remain high.MethodsThis study compares two procedures for retaining mature ookinetes from blood stage cultures, whilst removing red blood cells and other contaminants prior to further culture of the parasite. The well established method of isolation on Nycodenz cushions is compared with a novel method utilizing the innate magnetic properties of the haem pigment crystals found in the cytoplasm of ookinetes.ResultsYield and viability of ookinetes were similar with both isolation methods. However, in our hands magnetic isolation produced a cleaner ookinete preparation much more quickly. Moreover, decreasing the flow rate through the magnetic column could further enhance the yield.ConclusionWe recommend the enrichment of an ookinete preparation prior to further culture being performed using the magnetic properties of Plasmodium berghei ookinetes as an alternative to their density. The former technique is faster, removes more erythrocytes, but day-to-day costs are greater.

Pigmentation of Vat Blue RS by ball milling in solvents

Pigmentation of Vat Blue RS by ball milling in the presence of organic solvents or water was carried out and the effects of ball milling time, characteristics of solvent used and two-step ball milling on the transformation of crystal phase and the resulting pigment properties were studied. Experimental results showed that the α-phase of C.I. Pigment Blue 60 can be obtained by ball milling 2 h in the presence of xylene and NaCl. The rate of transformation to the α-phase was improved with an increase in the proportion of aromatic solvents in the medium employed. By milling in an aqueous medium without organic solvents, the original pigment crystal phase was destroyed.