Structure Of Pigment Research Articles

Physico‐chemical characterisation and light stability of dyes and pigments found in cultural heritage objects: Insights from microfading testing for assessing light fastness

AbstractUnderstanding the chemistry of dyes and pigments found in cultural heritage objects and their permanence is central for their preservation. Heritage science research has generally focused on either identification of materials present on actual objects or accelerated and natural ageing of mock‐up samples prepared using historically accurate methods to simulate the materiality of cultural heritage objects. A more recent strategy is the integration of these two research areas, which provides a holistic approach to assess both the chemical composition and stability of materials. Over the last 30 years, microfading testing (MFT) has notably contributed to understanding materials' responsiveness to light, minimising damage to objects from museum lighting and revealing insights into molecular structures of dyes and pigments, when employed in conjunction with other techniques. By combining MFT with diverse analytical methods, including imaging, spectroscopy, microscopy and chromatography, a more comprehensive approach is achieved. This joined‐up strategy contributes to improved decision‐making processes in the conservation and preservation of cultural heritage objects.

The Production of Melanin Pigments From Some Pathogenic Fungi in Response to L-Tyrosine Under Laboratory Conditions

Background: This study aims to evaluate response of plant pathogenic fungi to the amino acid L-tyrosine through the production of melanin. Methods: Potato dextrose broth (PDB) and PDB with 1% L-tyrosine were used for current evaluation. Melanin was produced, extracted and characterized from pathogenic fungi that infected rice in Iraq. Results: Results indicated that L-tyrosine was used as a source of the precursor by fungi belonging to Bipolaris. spicifera R15, Alternaria. alternata R18, Exserohilum. rostratum R19, Alternaria. alternate R20, and Alternaria. tenuissima R23, also produced higher levels of condensed black pigment. While, fungi like Nigrospora oryzae R9, Curvularia lunata R7, C lunata R21 and A tenuissima R24 were used more than one pathway for melanin production. UV transmittance increased significantly from 600 nm to 300 nm whereas absorbance decreased at 260 and 280 nm for all of the studied fungi. Analysis of FT-IR spectra and related assignment group of resolved that melanin extracted from B. spicifera R15 (3408.22), A. alternate R20 (3392.79), and A. tenuissima R24 (3387). Wavenumbers 2924 cm−1 and 2854 cm−1 were found in E. rostratum R19, A. alternative R20, and A. tenuissima R24 melanin extracts, respectively. Meanwhile, B. spicifera R15 revealed a single peak at 2929 cm−1. 3007.02 cm−1, 3072.6 cm−1, 3074.53 cm−1, 2920.3 cm−1, 2704.2 cm−1, and 1861.31 cm−1 are also assigned wavenumbers. Conclusion: Melanin-like pigments are produced via L-tyrosine-dependent and independent pathways. All colors extracted from fungal hyphae were morphologically and chemically identical to melanin. A UV scan and FT-IR analysis revealed differences in the physical appearance of building units and the structure of the melanin pigment produced by plant pathogenic fungi.

DERMOSCOPIC FEATURES OF BASAL CELL CARCINOMA: SYSTEMATIC REVIEW

Abstract Background: Basal cell carcinoma is one of the most common cancers worldwide, it is a locally destructive and slowly spreading tumor arising from the epidermis or hair follicles, in which the peripheral cells are similar to the cells of the basal layer of the epidermis and which rarely metastasize. Despite its slow growth and low potential for metastasis, basal cell carcinoma (BCC) is one of the most pressing problems in dermato-oncology due to its high incidence rates, variety of clinical forms and frequent relapses after any treatment methods. Currently, the most accessible non-invasive method for examining skin tumors is dermatoscopy. Aim: The purpose of this review is to highlight the dermoscopic features encountered in basal cell carcinoma and to outline the role of dermoscopy for diagnosis this cancer. Methodology: The systematic review included articles from Google Scholar, Medline, Scopus, Web Of Sciences, PubMed was conducted. For the search, the following keywords were included: dermoscopy of pigmented form of basal cell carcinoma; dermoscopy of nonpigmented form of basal cell carcinoma. Results: Conducted a preliminary search and reviewed 62 titles and abstracts in this review and 27 full-text articles were selected of high methodological quality. Dermoscopy is a non-invasive technique, which allows early diagnosis based on the presence of typical vascular structures, pigmented structures, and ulceration and the absence of specific melanocytic structures. However, the use of dermoscopic technique is limited by the lack of prognostically significant dermatoscopic criteria confirming the different morphological nature of tumor growth. Conclusion: The current systematic review demonstrated, based on the observed features, this method allows for differential diagnosis of malignant and benign, as well as melanocytic and non-melanocytic skin neoplasms, as well as diagnosis of tumors at the earliest stage of their development.

Different molecular structure of pigments versus traditional UV Stabilizers on the UV irradiation life of HDPE

As the demands on high-density polyethylene for weather resistance, aesthetics and functionality continue to improve, copper phthalocyanine has recently received attention for enhancing the weathering properties of high-density polyethylene. However, little research has been done on other pigments whether to improve weathering resistance equally. In this work, inorganic and organic pigments added to matrix were explored and compared with the industrialized UV stabilizers. It was found that pigmented polyethylene showed very little color change during 2000 h irradiation except for polyethylene/ultramarine. After 2000 h irradiation, polyethylene/copper phthalocyanine was the best among pigmented polyethylene in tensile strength, copper polychlorinated phthalocyanine following. These two pigments were similar to commonly used light stabilizers in their ability to stop the aging of polyethylene. Chrome oxide and ultramarine were worse, basically aging after irradiation of 500 h. This was consistent with the order of UV absorption ability of pigments at 310 nm - 400 nm.

Importance of Both Clinical and Dermoscopic Findings in Predicting High-Risk Histopathological Subtype in Facial Basal Cell Carcinomas.

Being able to recognize high-risk facial basal cell carcinoma (BCC) may lead to fewer incomplete excisions and inappropriate treatments. We sought to investigate clinical and dermoscopic criteria for predicting facial BCC subtypes, analyze the interobserver agreement between readers, and develop a diagnostic algorithm to predict high-risk histopathological subtype. In this single-center, retrospective investigation, 6 independent readers evaluated predefined clinical and dermoscopic criteria in images of histopathologically verified primary facial BCCs including: topography, border demarcation, vessels, ulceration, white porcelain areas, shiny white blotches and strands, and pigmented structures and vessels within ulceration. Overall, 297 clinical and dermoscopic image pairs were analyzed. The strongest associations with high-risk subtype were: "bumpy" topography (OR 3.8, 95% CI, 3.1-4.7), ill-defined borders (OR 3.4, 95% CI 3.1-4.7), white porcelain area (OR 3.5, 95% CI 2.8-4.5), and vessels within ulceration (OR 3.1, 95% CI 2.4-4.1). Predominantly focused vessels were a positive diagnostic criterium for either nodular (OR 1.7, 95% CI 1.3-2.2) or high-risk (OR 2.0, 95% CI 1.6-2.5) subtypes and a strong negative diagnostic criterium for superficial BCC (OR 14.0, 95% CI 9.6-20.8). Interobserver agreement ranged from fair to substantial (κ = 0.36 to 0.72). A diagnostic algorithm based on these findings demonstrated a sensitivity of 81.4% (95% CI, 78.9-83.7%) and a specificity of 53.3% (95% CI, 49.7-56.9%) for predicting high-risk BCC subtype. Integration of both clinical and dermoscopic features (including novel features such as topography and vessels within ulceration) are essential to improve subtype prediction of facial BCCs and management decisions.

Influence and progress of tea pigment research: A comprehensive analysis of application of bibliometrics

Tea pigment, as a natural pigment component in tea, has attracted much attention because of its unique health benefits. In recent years, with the deepening of scientific research, the research on biological activity, extraction technology and application of tea pigment has made remarkable progress. Through systematic bibliometrics analysis, this paper comprehensively combs and evaluates the research status of tea pigment. The propose is to provide valuable reference for future research and application. In this paper, the chemical structure of tea pigment is firstly summarized, and then its diverse biological activities, such as antioxidant, anti-inflammatory and anti-tumor, are deeply discussed, especially its potential application in the treatment of cardiovascular diseases and diabetes. In addition, the application prospect of tea pigment in food coloring, textile dyeing and other industrial fields is also discussed in detail. Through the collection and arrangement of a large number of research literatures, this paper analyzes the development trend, research methods and main achievements of tea pigment research, and pays special attention to the dosage and effect of tea pigment in practical application. These analyses not only contribute to a more comprehensive understanding of the characteristics and functions of tea pigments, but also provide scientific basis for the further development and application of tea pigments.

Application of ZnAl layered double hydroxides for the formulation of stable and safe cosmetic pigments

Purpose This study aims to produce composite pigments, including SHS/ZnAl-LDHs, IDS/ZnAl-LDHs and SNND/ZnAl-LDHs, with improved coloration, enhanced photostability and thermostability and biocompatibility. Design/methodology/approach The chemical structures of the composite pigments were characterized by X-ray diffraction spectroscopy and Fourier transform infrared spectroscopy. Photostability and thermal stability were assessed using ultraviolet-visible spectroscopy and colorimetry. The coverage of the dyes was determined through black-and-white tile testing, and specific RGB values were used to indicate color expressiveness. Finally, a four-color eyeshadow was formulated, and safety tests were conducted via human patch test and cellular assays to confirm the safety and reliability of the samples. Findings The experimental results demonstrate an enhancement in the photo and thermal stability of the SHS/ZnAl-LDHs, IDS/ZnAl-LDHs and SNND/ZnAl-LDHs composites, along with their superior performance in terms of covering power and color saturation. These composite pigments also exhibit high safety, making them well-suited for cosmetic applications. Practical implications The composite pigments based on hydrotalcite can be used in the cosmetic industry without causing any harm to the environment and human health. Originality/value The addition of hydrotalcite enables better application of pigments in cosmetics.

Identification of novel flower anthocyanins of Delphinium grandiflorum cultivars

Flower color is one of the most important properties of ornamental flowers. Information on the kinds of pigments that flowers can biosynthesize is useful for breeding cultivars focused on flower colors. The flower colors of regular ornamental delphinium cultivars are blue, violet, purple, pink, and white. The pigments of these flowers are delphinidin-based anthocyanins. It has been reported that the typical modification in delphinium anthocyanins involves the transfer of glucose and p-hydroxybenzoic acid molecules to the 7-position of delphinidin one by one, and it was predicted that other unidentified anthocyanins are present in addition to the already reported ones. Recently, light pink flowers that accumulate pelargonidin-based anthocyanins were reported from cultivars derived from Delphinium grandiflorum. Converting delphinidin-based anthocyanins to pelargonidin-based ones is considered key to producing red flowers in delphinium. Hence, we investigated anthocyanins of blue, mauve, light pink, and white flowers of D. grandiflorum cultivars. We isolated anthocyanins and analyzed them using HPLC, TLC, UV–vis spectra, FABMS, and NMR. Using these methods, we identified two novel delphinidin-based anthocyanins and three novel pelargonidin-based anthocyanins: delphinidin 3-O-[6-O-(α-rhamnopyranosyl)-β-glucopyranoside]-7-O-[6-O-(p-hydroxybenzoyl)-β-glucopyranoside] (2), pelargonidin 3-O-[6-O-(α-rhamnopyranosyl)-β-glucopyranoside]-7-O-[6-O-(4-O-(6-O-(p-hydroxybenzoyl)-β-glucopyranosyl)-p-hydroxybenzoyl)-β-glucopyranoside] (5, rubrodelphin), pelargonidin 3-O-[6-O-(α-rhamnopyranosyl)-β-glucopyranoside]-7-O-[3-O-(β-glucopyranosyl)-6-O-(4-O-(6-O-(p-hydroxybenzoyl)-β-glucopyranosyl)-p-hydroxybenzoyl)-β-glucopyranoside] (6), delphinidin 3-O-[6-O-(α-rhamnopyranosyl)-β-glucopyranoside]-7-O-[3-O-(3-O-(6-O-(p-hydroxybenzoyl)-β-glucopyranosyl)-β-glucopyranosyl)-6-O-(4-O-(6-O-(p-hydroxybenzoyl)-β-glucopyranosyl)-p-hydroxybenzoyl)-β-glucopyranoside] (7), and pelargonidin 3-O-[6-O-(α-rhamnopyranosyl)-β-glucopyranoside]-7-O-[3-O-(3-O-(6-O-(4-O-(6-O-(p-hydroxybenzoyl)-β-glucopyranosyl)-p-hydroxybenzoyl)-β-glucopyranosyl)-β-glucopyranosyl)-6-O-(4-O-(6-O-(p-hydroxybenzoyl)-β-glucopyranosyl)-p-hydroxybenzoyl)-β-glucopyranoside] (9, rosedelphin), along with four known anthocyanins. The flowers of five blue cultivars accumulated cyanodelphin (8) as the dominant pigment. The shapes of visible absorption spectra of these five blue flowers were similar, indicating that the color and the absorption spectra were the typical ones for delphinium blue color produced by 8. The mauve flower color was due to a mixture of delphinidin-based anthocyanins in various polyacylated levels at the 7-position. The light pink flowers accumulated pelargonidin-based anthocyanins 5, 6, and 9. These pigment structures showed that the pelargonidin-based anthocyanins modified in the same way as in the originally biosynthesized delphinidin-based anthocyanins even though aglycone was replaced by pelargonidin in these anthocyanins.

Characterization, components, and chemical structure of a novel natural pigments derived from Streptomyces tauricus

Characterization, components, and chemical structure of a novel natural pigments derived from Streptomyces tauricus

Dermoscopy and In Vivo Confocal Microscopy Findings of Basal Cell Carcinomas in Xeroderma Pigmentosum Patients.

Xeroderma pigmentosum (XP) is a rare inherited disorder with a high incidence of malignant tumours. Literature data on dermoscopic and in vivo reflectance confocal microscopy (RCM) findings in patients with XP are very limited. Dermoscopic findings in 32 biopsy-proven BCCs and RCM findings in 10 biopsy-proven BCCs developed in seven XP patients were reviewed. Of 32 BCCs, 28 were pigmented. On dermoscopy, BCCs exhibited multiple grey-blue globules/dots (81, 3%), short-fine telangiectasias/fine arborising vessels (65, 6%), multiple grey-blue ovoid nests (53, 1%), white structures (white-red structureless areas/shiny white areas/lines/strands) (56, 3%), arborising vessels (37, 5%), brown nests/globules/dots (28, 1%), spoke-wheel structures (9, 4%), leaf-like areas (9, 4%), ulceration (28, 1%), peripheral network (21, 9%), and multiple aggregated yellow-white globules (3, 1%). In 10 lesions in which further imaging with RCM was performed, RCM findings differentiated BCC from other tumours, including primary melanoma. Although the dominancy of pigmented structures may imitate melanoma clinically, dermoscopy is a valuable tool in the early diagnosis of BCCs in patients with XP. For suspicious lesions, RCM can help in differentiating pigmented BCC from primary melanoma.

Dermoscopic Features of Pigmented Bowen Disease: A Multicenter Study on Behalf of the Ibero-Latin American College of Dermatology (CILAD).

Studies focused on dermoscopic aspects of pigmented Bowen disease (pBD) in Latin American population are scarce and limited to only case reports or small series. To report dermoscopic findings in a large series of 147 pBD diagnosed in Ibero-Latin American population. We conducted a multicentric, retrospective study on 147 histologically proven pBD under the auspices of the Dermoscopy Chapter of the Ibero-Latin American College of Dermatology. The study population consisted of 77 females (52%) and 70 males (48%) with a mean age of 68.6 years. 70.1% of patients had skin phototype 3, 15.6% to skin phototype 2, and 14.3% to skin phototype 4. On clinical examination, near 60% of pBD were flat, 70% presented with scales, and 90% were asymmetric. Under dermoscopy, structureless hypopigmented areas, dots brown and pink color were the most frequently observed. Regarding specific dermoscopic clues to pBD, the most prevalent were structureless hypopigmented areas, vessels arranged in linear fashion at the periphery, and pigmented lines or pigmented dots distributed in a linear fashion. Clustered, coiled, and dotted vessels were observed in 55.8%, 45.6%, and 45.6% of the cases, respectively. We report a large series of cases of pBD in Latin American patients, with most patients being skin phototype 3 and 4. Distinctively in our study, the pigmented structures and the clues derived from the presence of melanin were much more frequent than in previous reports in fair skin.

Non-destructive three-dimensional imaging of artificially degraded CdS paints by pump-probe microscopy

Cadmium sulfide (CdS) pigments have degraded in several well-known artworks, but the influence of pigment properties and environmental conditions on the degradation process have yet to be fully understood. Traditional non-destructive analysis techniques primarily focus on macroscopic degradation, whereas microscopic information is typically obtained with invasive techniques that require sample removal. Here, we demonstrate the use of pump-probe microscopy to nondestructively visualize the three-dimensional structure and degradation progress of CdS pigments in oil paints. CdS pigments, reproduced following historical synthesis methods, were reproduced as oil paints and artificially aged by exposure to high relative humidity and light. The degradation of CdS to CdSO4·xH2O was confirmed by both FTIR (Fourier-transform infrared) and XPS (x-ray photoelectron spectroscopy) experiments. During the degradation process, optical pump-probe microscopy was applied to track the degradation progress in single grains, and volumetric imaging revealed early CdS degradation of small particles and on the surface of large particles. This indicates that the particle dimension influences the extent and evolution of degradation of historical CdS. In addition, the pump-probe signal decrease in degraded CdS is observable before visible changes to the eye, demonstrating that pump-probe microscopy is a promising tool to detect early-stage degradation in artworks.

X-ray fluorescence analysis in the study of paintings – an overview

Energy dispersive X-ray fluorescence analysis (EDXRF) is an excellent method in investigations of cultural heritage treasures, including easel and wall paintings and illuminations in ancient manuscripts. As one of the few methods applicable for this purpose, it is non-destructive and non-invasive. It is often combined with other methods such as optical microscopy, visible light photography, UV fluorescence photography, infrared reflectography, Fourier transform infrared spectroscopy, X-ray radiography, Raman spectrometry and others. The complex layered structure and mixtures of pigments, especially on easel paintings, represent a challenging task from the point of view of analysis. However, without taking samples it is only possible to analyse the thin surface layer of the investigated object with a thickness of tens to a few hundreds of micrometres. Nevertheless, this is not too much a problem when analysing paintings and even more so in the analysis of illuminations in manuscripts. The paper has an overview character and aims to summarise the possibilities, advantages and problems of XRF in this area and to demonstrate them on selected examples of published works, which in some cases are devoted to the works of leading painters from various historical periods (Giotto di Bondone, Antonello da Messina, Raffaelo Sanzio, Antonio Allegri da Corregio, Anthonis van Dyck, Rembrandt van Rijn, Giorgio Marini, Pablo Picasso and others). This review includes also a brief mention of selected research carried out in our laboratory.

Cu(II)-binder complexes in azurite and malachite pictorial mixtures: An EPR study

Degradation processes of paintings, frescos, illuminations, and painted decorations represent a relevant challenge in the cultural heritage field for both conservators and scientists dealing with the causes of these processes. It is very important understanding the molecular origin of colour changes, like fading, yellowing, blackening, as well as the molecular origin of damages due to degradation, like cracking and fall of pictorial layers. Metal complexes, often indicated as “metal soaps”, when referred to metal carboxylates, play a relevant role in degradation. However, their identification is not easy, and the involvement of the metal ions in the degradation mechanisms is often not clear. Continuous Wave Electron Paramagnetic Resonance (CW-EPR) spectroscopy is a very sensitive tool towards paramagnetic species (e.g., transition metal ions like Fe(III), Cu(II), Mn(II), radicals, etc.), providing relevant information on these species, not always well-characterized with other methods. In this paper, we use CW-EPR to study the formation of Cu(II)-binder complexes in natural malachite and azurite pigments mixed with several organic binders. We show that CW-EPR technique is able to detect easily Cu(II) complexes with organic ligands, and can additionally provide information on the pigments themselves. In particular, the first coordination sphere of the Cu(II) complexes is characterized by applying the Peisach-Blumberg method. Moreover, CW-EPR shows that binders can affect the structure of the raw pigments.

The design and calculation of the infrared properties for low emissivity coatings dependent on the structure and distribution of flake Al pigments

Flake Al pigment is the main component of infrared low emissivity coatings, which plays an important role in controlling the coating‘s infrared optical properties. To clarify this influence mechanism, the flake Al powder with controllable thickness and particle size were prepared by the method of physical vapor deposition combined with ultrasonic crushing. The effects of structure parameters for flake Al powder, such as thickness and particle size, on the surface morphology and infrared emissivity of the coating was systematically studied. The results show that the smaller particle size leads to poorer directional arrangement degree of flake Al powder and increased edge scattering. The thinner thickness results in more absorption probability from resin to infrared radiation, thereby decreasing the infrared reflectivity and increasing the infrared emissivity of coating. These experimental phenomena are effectively elucidated by the calculation of bidirectional reflectance distribution function based on the Comsol software. Moreover, the Kubelka layer model optimized by the rough surface model was used to explain and predict the correlation between the infrared emissivity of the coating and the particle size and thickness of the flake Al powder. Based on the measured surface roughness of the coating and the complex refractive index of the flake Al powder, the error between the experimental and calculated results is only 1.2 %. The calculated model predicts that the coating exhibits lowest infrared emissivity when the thickness of flake Al powder is 400 nm. This work holds a significant guidance for the subsequent preparation of infrared low-emissivity coatings.

Dermoscopic features of pigmented basal cell carcinoma according to size.

Basal cell carcinoma (BCC), the most common skin cancer in humans, requires early detection. Dermoscopy enhances diagnostic accuracy through a noninvasive approach. Pigmented BCC (pBCC) is characterized by distinctive dermoscopic features, including the presence of pigmented globules or nests. While dermoscopic features of large pBCC (size >6 mm) have been extensively studied, limited data are available on small pBCC (size ≤6 mm) and its relationship with tumor progression. Dermoscopic images of histologically proven pBCCs were collected between 2014 and 2022 at Hualien Tzu Chi Hospital. Each image was analyzed for patterns of pigmentation, vasculature, and epidermal and dermal structures. Statistical analysis was performed to compare the differences according to the size and the trend during tumor progression. In total, 135 pBCCs (48 small and 87 large) were included. Pigment structures were present in all cases. Short fine telangiectasia and small erosions constituted over 85% of the cases, showing no significant distinction between small and large pBCCs, nor any specific pattern correlating with tumor enlargement. The number of arborizing vessels, ulcerations, and shiny white structures showed an increasing trend associated with size progression. Arborizing vessels appeared when tumor size exceeded 6 mm. This study provides a dynamic interpretation of the dermoscopic features of pBCC according to size enlargement. Short fine telangiectasia and small erosions are highly important features for the early diagnosis of small pBCCs. Arborizing vessels, ulceration, and shiny white structures are more frequent in large pBCCs, and they increase in association with tumor progression.

Dermatoscopic profiling of inverted follicular keratosis indifferent skin phenotypes.

Inverted follicular keratosis (IFK) is a rare benign tumour of the follicular infundibulum. Owing to its similarity to other benign and malignant cutaneous lesions, it poses a diagnostic challenge. There is limited information on the dermatoscopic characteristics of IFK and the majority of cases have been reported in patients with lighter skin types. To describe the prevalent dermatoscopic features of IFK, especially in patients with skin of colour. We retrospectively analysed 35 histopathologically verified cases of IFK from a single university hospital in Turkey. With respect to the Fitzpatrick skin phototype, 2 (6%), 12 (34%), 16 (46%) and 5 (14%) patients had Fitzpatrick skin phototypes II, III, IV and V, respectively. Clinically, the majority of IFKs were hypopigmented or nonpigmented (83%). Pink-white structureless areas (54%), ulceration (54%), a central keratin mass (43%) and blood spots on keratin mass (43%) were the most frequent dermatoscopic findings. Pigmented structures were observed as blue-grey structureless areas in 12 lesions and as blue-grey clods in 5, primarily in Fitzpatrick phototype IV and V skin. The incidence of a pink, structureless area and blood spots on ulceration was found to be statistically significantly higher in individuals with fairer skin types, while a greater prevalence of blue-grey coloration was observed in those with skin of colour (P < 0.05). Although our study found some distinguishing dermatoscopic findings in IFK, diagnosis is generally confirmed by histopathology, as the clinical appearance and dermatoscopic findings may not be sufficient to differentiate it from other tumours, especially squamous cell carcinoma or keratoacanthoma. The dermatoscopic characteristics of dark skin are comparable to those of pale skin; however, hyperpigmentation can be more noticeable in skin of colour.

Clinicopathological, Immunohistochemical, and Molecular Characteristics of Pigmented Microcystic Chromophobe Renal Cell Carcinoma with Favorable Prognosis.

Background. Pigmented microcystic chromophobe renal cell carcinoma (RCC) is a subtype of chromophobe RCC. Its distinct histopathologic features are microcystic and microtubular pattern, pigmentation, and microcalcifications. Pigmented microcystic chromophobe RCC has ultrastructure, immunophenotypic structure, and molecular results similar to chromophobe RCC. Methods. We report five tumors of pigmented microcystic chromophobe RCC. Morphological observation and immunohistochemical examination were performed, and clinical and molecular features were analyzed. Results. Microscopically, all five tumors showed brown pigmentation, microcystic, and tubular cystic structures, one tumor presented microscopic calcifications. All tumors were positive for EMA, AE1/AE3, PAX8, KRT7, KIT (CD117), claudin 7, KRT8, and E-cadherin, and three tumors expressed P504S. All tumors were negative for vimentin, CA9, KRT20, TFE3, TFEB, Melan-A, HMB45, FH, SDHB, and GATA3. Ki-67 index varied from less than 1% to 2%. In three tumors, next-generation sequencing of the 688 gene was performed, the results found gene variants with potential clinical significance such as JMJD1C, MYCL, TP53, PI3KCA, KRAS, APC, GLI1, LRRK2, and gene variants with unclear clinical significance such as NTRK1 and RAD50; All patients remained alive over a follow-up period of 8-46 months without tumor recurrence and sarcomatoid transformation. Conclusions. Pigmented microcystic chromophobe RCC has a relatively benign biological behavior, and distant metastases and sarcomatoid transformation are rare. This overview of five additional tumors of pigmented microcystic chromophobe RCC offers further insight into this special subtype of chromophobe RCC.

Structure and morphology of red pigments based on sepiolite.

Sepiolite is an important raw fibrous material. A method to prepare red pigments based on sepiolite through the thermal treatment of sepiolite with sulfur and sodium sulfide hydrate is reported. Sepiolite was heated until 800 °C in order to remove zeolitic water, the first coordinated water, the second coordinated water, and structural hydroxyls. Several [S/Na2S]molar ratios in the range 0.5-7 were employed. The properties of these pigments were studied by different analytical techniques, such as colorimetric analysis, thermal analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction and scanning electron microscopy. The samples with [S/Na2S] = 0.5 and 1, corresponding to high contents of sodium sulfide in the synthesis procedure, exhibit high values of the colorimetric parameter CIE a* and a maximum reflectance in the visible zone belonging to red, based on the red colour of the samples. Under the reducing conditions of the synthesis, sulfur forms polysulfides of the general formula [Sx]2-. The sodium sulfide reacts with the excess S to form polysulfides as well. From the polysulfides, the radical anions of the general formula [Sx/2]˙- originate and they are identified as the chromophore groups responsible for the color in the sulfur-based pigment analogues of ultramarines. The red colour of the samples could be mainly attributed to the presence of S4 and S4˙- identified by FTIR.

Structural, electronic, and optical properties of CaCoSi2O6 and Ca2CoSi2O7 blue pigments: A combined experimental, DFT+U, and BSE study

The exceptional characteristics of pigments, such as their high thermal stability, affordable production costs, and easy manufacturing procedures, are the reasons for their steady growth in industrial applications. On the other hand, the use of theoretical computations to forecast pigment color is a novel and significant area of study. In this study, CaCoSi2O6 (co-pyroxene) and Ca2CoSi2O7 (co-akermanite) pigments were synthesized using a conventional ceramic method. We studied the structural, magnetic, electronic, optical, and colorimetric properties of the pigments within experimental and theoretical approaches. The structural characteristics of the pigments were investigated by X-ray diffraction technique (XRD), Scanning Electron Microscope (SEM), UV–visible (UV–Vis) spectroscopy, and color measurement (CIE L*a*b*) colorimetry methods. Also, Hubbard Density Functional Theory (DFT + U) calculations were performed using 40 atoms of co-pyroxene and 24 atoms of co-akermanite. We employed the Bethe-Salpeter equation (BSE) method for studying the absorption spectrum and color of pigment samples. The theoretical energy gap values for the CaCoSi2O6 and Ca2CoSi2O7 structures were determined to be 4.2eV and 3.5eV, respectively. While the direct experimental band gap for CaCoSi2O6 and Ca2CoSi2O7 is about 4eV and 3.9eV, respectively. Comparing the outcomes, it can be inferred that the BSE method represents a valuable approach to predicting the absorption spectra and color features of pigment structures.