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Keywords = multicolor composites

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45 pages, 5089 KB  
Review
A Review on the Synthesis Methods, Properties, and Applications of Polyaniline-Based Electrochromic Materials
by Ge Cao, Yan Ke, Kaihua Huang, Tianhong Huang, Jiali Xiong, Zhujun Li and He Zhang
Coatings 2026, 16(1), 129; https://doi.org/10.3390/coatings16010129 - 19 Jan 2026
Abstract
Polyaniline (PANI), characterized by its proton-coupled redox mechanism and multicolor reversibility, is widely investigated for adaptive optical interfaces. Compared to inorganic oxides, PANI offers advantages in cost-effectiveness, mechanical flexibility, and molecular tunability; however, its practical implementation faces challenges related to kinetic limitations and [...] Read more.
Polyaniline (PANI), characterized by its proton-coupled redox mechanism and multicolor reversibility, is widely investigated for adaptive optical interfaces. Compared to inorganic oxides, PANI offers advantages in cost-effectiveness, mechanical flexibility, and molecular tunability; however, its practical implementation faces challenges related to kinetic limitations and environmental instability. This review presents a comprehensive analysis of PANI-based electrochromic materials, examining the intrinsic correlations among synthesis methodologies, microstructural characteristics, and optoelectronic performance. Synthesis strategies, including chemical oxidative polymerization, electrochemical deposition, and template-assisted techniques, are evaluated. Emphasis is placed on resolving the trade-off between optical contrast and switching kinetics by constructing high-surface-area porous nanostructures and inducing chain ordering via functional dopants to shorten ion diffusion paths and reduce charge transfer resistance. Fundamental electrochromic properties are subsequently discussed, with specific attention to degradation mechanisms triggered by environmental factors, such as pH drift, and stabilization strategies involving electrolyte engineering and composite design. Furthermore, the review addresses the evolution of applications from single-band monochromatic displays to dual-band smart windows for decoupled visible/near-infrared regulation and multifunctional integrated systems, including electrochromic supercapacitors and adaptive thermal management textiles. Finally, technical challenges regarding long-term durability, neutral color development, and large-area manufacturing are summarized to outline future research directions for PANI-based optical systems. Full article
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15 pages, 8541 KB  
Article
Application of Laser-Induced Breakdown Spectroscopy and Principal Component Analysis for Compositional Zoning of Liddicoatite Tourmaline from Anjanaboniona
by Nancy J. McMillan and Anna VanDusen
Minerals 2025, 15(12), 1243; https://doi.org/10.3390/min15121243 - 25 Nov 2025
Viewed by 398
Abstract
Tourmalines from the Anjanabonoina pegmatite field, Central Madagascar, exhibit some of the most complex multi-color zoning patterns known. These tourmalines are also rare because of their unusual Ca- and Li-rich liddicoatite composition. Liddicoatite specimens crystallize in miarolitic pockets in pegmatites, which periodically break [...] Read more.
Tourmalines from the Anjanabonoina pegmatite field, Central Madagascar, exhibit some of the most complex multi-color zoning patterns known. These tourmalines are also rare because of their unusual Ca- and Li-rich liddicoatite composition. Liddicoatite specimens crystallize in miarolitic pockets in pegmatites, which periodically break open and seal. Multivariate analysis of Laser-Induced Breakdown Spectroscopy (LIBS) spectra of an Anjanabonoina liddicoatite specimen allows evaluation of simultaneous changes in all elements during crystallization. LIBS is an optical emission technique in which photons emitted from a cooling laser plasma are diffracted and recorded as a spectrum. All elements present in the sample at concentrations above their inherent detection limits are represented by peaks in the spectrum. Principal Component Analysis of 123 LIBS spectra acquired in a core-to-rim traverse reveals six major compositional zones that suggest four stages of crystallization, the last three of which begin with the opening of the pocket and mixing of pegmatitic fluids with those from the metasedimentary host rocks. Full article
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14 pages, 1780 KB  
Article
Altered Endometrial Memory T-Cell Profiles During the Window of Implantation in Women with Previous Miscarriage
by Dimitar Parvanov, Rumiana Ganeva, Margarita Ruseva, Maria Handzhiyska, Jinahn Safir, Lachezar Jelezarsky, Dimitar Metodiev, Georgi Stamenov and Savina Hadjidekova
Biomedicines 2025, 13(11), 2800; https://doi.org/10.3390/biomedicines13112800 - 17 Nov 2025
Viewed by 377
Abstract
Aim: This study aimed to characterize and compare the composition of central (TCM), effector (TEM), tissue-resident (TRM), and terminally differentiated (TEMRA) memory T cells in mid-luteal endometrium during the window of implantation (WOI) in women with and without a previous miscarriage. Methods: Stromal [...] Read more.
Aim: This study aimed to characterize and compare the composition of central (TCM), effector (TEM), tissue-resident (TRM), and terminally differentiated (TEMRA) memory T cells in mid-luteal endometrium during the window of implantation (WOI) in women with and without a previous miscarriage. Methods: Stromal lymphocytes from endometrial samples (P + 5) were analyzed by multicolor flow cytometry to quantify total, CD4+ and CD8+ TCM (CD45RACCR7+), TEM (CD45RACCR7), TRM (CD69+), and TEMRA (CD45RA+CCR7) subsets. Participants were grouped as having no previous miscarriage (n = 38) or ≥1 previous miscarriage (n = 33), and the relative distribution of these memory subsets was compared between groups. Correlations, PCA and logistic regression were used to assess global memory network organization. Results: Women with prior miscarriage exhibited higher TCM proportions among total and CD8+ lymphocytes (p < 0.01), alongside lower CD8+ TEM (p = 0.02) and higher CD4+ TEM (p = 0.01). TRM showed a mild, non-significant increase (p = 0.18), while TEMRA remained stable. TRM correlated positively with both TCM (r = 0.51) and CD4+ TEM (r = 0.40), indicating coordinated organization among memory subsets. Multivariate analyses (PCA and logistic regression) confirmed these trends and identified the TCM/TEM ratio as the most discriminative parameter. Conclusions: Endometrial memory T-cell composition during the WOI differs in women with miscarriage history, characterized by central memory expansion and reduced effector memory proportions, with parallel increases in tissue-resident cells. These changes suggest persistent remodeling of the local immune memory network toward a long-lived, less differentiated phenotype that may influence implantation readiness in subsequent cycles. Full article
(This article belongs to the Section Immunology and Immunotherapy)
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16 pages, 3788 KB  
Article
Color Genesis and Compositional Features of Red-Blue Colored Gem-Quality Corundum from Malipo, China
by Hui Wang, Xiao-Yan Yu, Guang-Ya Wang, Masroor Alam, Lan Mu, Ying-Xin Xu and Fei Liu
Minerals 2025, 15(11), 1099; https://doi.org/10.3390/min15111099 - 22 Oct 2025
Viewed by 614
Abstract
The newly discovered multi-colored corundum (gem quality) alluvial deposit in Malipo, Yunnan Province, is one of the most famous sapphire deposits in China. However, the coloration mechanism and genesis of red-blue colored corundum (RBCC) remain enigmatic. In this study, conventional gemological techniques such [...] Read more.
The newly discovered multi-colored corundum (gem quality) alluvial deposit in Malipo, Yunnan Province, is one of the most famous sapphire deposits in China. However, the coloration mechanism and genesis of red-blue colored corundum (RBCC) remain enigmatic. In this study, conventional gemological techniques such as ultraviolet–visible (UV-vis) spectroscopy and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were employed on an RBCC suite, with a view to unravel its coloration mechanism and compositional characteristics. The results show that the element pairs of Cr3+, Fe2+-Ti4+, and Fe3+-Fe3+ in principle contribute to the red coloration, while the blue color in corundum is predominantly caused by the Fe2+-Ti4+ pair, and subordinately by Cr3+ and Fe3+. Cr is likely the cause of the purple color. The Cr content in the red zone is significantly higher than that in the blue zone, while the Ti and V contents in the red zone are notably lower than in the blue zone. High Cr/Ga and (V + Cr)/Ga values of the Malipo RBCC suggest a metamorphic origin. All color zones of RBCC demonstrate stability in Ga content and an extremely low content of Mg, with minor fluctuations in Fe content, indicating that the formation process of the Malipo RBCC was influenced by magma mixing. Full article
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20 pages, 3357 KB  
Article
Noninvasive Cell Population Profiling of Normal and Dysplastic Cervical Biofluids by Multicolor Flow Cytometry as a Promising Tool for Companion Diagnostics
by Christoph Berger, Wolf Dietrich, Manuela Richter, Florian Kellner, Christian Kühne and Katharina Strasser
Cancers 2025, 17(20), 3328; https://doi.org/10.3390/cancers17203328 - 15 Oct 2025
Viewed by 733
Abstract
Background/Objectives: Cervical Pap smears are routinely used to detect cellular abnormalities as a cervical cancer screening tool and to assess the presence of HPV for risk stratification of the disease. Here, we aimed to extend the applications of this sampling procedure by [...] Read more.
Background/Objectives: Cervical Pap smears are routinely used to detect cellular abnormalities as a cervical cancer screening tool and to assess the presence of HPV for risk stratification of the disease. Here, we aimed to extend the applications of this sampling procedure by combining it with multicolor flow cytometry to characterize cell populations across cervical cancer disease stages. Methods: Cervical Pap smears from 30 patients with various disease stages ranging from normal to intraepithelial neoplasia up to treated cancers were analyzed as biofluids using multicolor flow cytometry. Individual samples were evaluated, and statistical analyses were performed over all sample stages. Cancer cell lines (CaSki, SiHa, HeLa, A549, U2OS) were examined as tumor cell controls. Results: Cervical biofluids were subdivided into cell populations according to their scattering properties and the expression of specific biomarkers: EpCAM and cytokeratin 8 for epithelial cells from tumors as well as healthy ectocervical and endocervical regions, and CD45 for immune cells. Discrimination of tumor cells was facilitated with cancer cell lines. Statistical analysis revealed that the composition of cell populations differs among disease stages, whereas treated cancer samples were consistently associated with a reduction in squamous epithelial cells and an increase in immune cells compared to normal samples. Conclusions: Herein, we identified the major cell populations in cervical biofluid samples and demonstrated that this method can detect changes in the cellular composition across different disease stages. This approach could be further exploited in cancer research and potentially serve as a companion diagnostic tool in tumor development, progression and during treatment. Full article
(This article belongs to the Special Issue Cervical Cancer Screening: Current Practices and Future Perspectives)
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16 pages, 2174 KB  
Article
Polyvinylpyrrolidone-Capped CuInS2 Colloidal Quantum Dots: Synthesis, Optical and Structural Assessment
by Oleg Korepanov, Olga Aleksandrova, Anna Botnar, Dmitrii Firsov, Zamir Kalazhokov, Demid Kirilenko, Polina Lemeshko, Vasilii Matveev, Dmitriy Mazing, Ivan Moskalenko, Alexander Novikov, Sviatlana Ulasevich and Vyacheslav Moshnikov
Colloids Interfaces 2025, 9(3), 33; https://doi.org/10.3390/colloids9030033 - 20 May 2025
Viewed by 1608
Abstract
Ternary metal chalcogenide quantum dots (QDs), such as CuInS2, have attracted significant attention due to their lower toxicity compared to binary counterparts containing cadmium or lead, making them promising candidates for biomedical imaging and solar energy applications. The surfactant choice is [...] Read more.
Ternary metal chalcogenide quantum dots (QDs), such as CuInS2, have attracted significant attention due to their lower toxicity compared to binary counterparts containing cadmium or lead, making them promising candidates for biomedical imaging and solar energy applications. The surfactant choice is critical for controlling nanocrystal nucleation, growth kinetics, and functionalization. This directly affects the toxicity and applications of QDs. In this work, we report a synthesis protocol for PVP-capped CuInS2 QDs in an aqueous solution. Using density functional theory (DFT) calculations, we predicted the coordination patterns of PVP on the CuInS2 QDs surface, providing insights into the stabilization mechanism. The synthesized QDs were characterized using TEM, XRD, XPS, and FTIR to assess their morphology, chemical composition, and surface chemistry. The QDs exhibited dual photoluminescence (PL) maxima at 550 nm and 680 nm, attributed to defect-related emissions, making them suitable for cell imaging applications. Cytotoxicity studies and cell imaging experiments demonstrate the excellent biocompatibility and effective staining capabilities of the PVP-capped CuInS2 QDs, highlighting their potential as fluorescent probes for long-term, multicolor cell imaging including two-photon microscopy. Full article
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14 pages, 3903 KB  
Article
Multiparametric Immune Profiles and Their Potential Role in HIV-1 Disease Progression and Treatment
by Junwei Su, Junjie Zhang, Qianying Wang, Xiaojing Liu, Shuo Wang, Yuhua Ruan and Dan Li
Pathogens 2025, 14(4), 347; https://doi.org/10.3390/pathogens14040347 - 4 Apr 2025
Viewed by 1132
Abstract
Backgrounds: The rapid initiation of highly active anti-retroviral therapy (HAART) can control HIV-1 viremia and stabilize the long-term health of people living with HIV-1 (PLWH). Despite this, individuals who are diagnosed late and exhibit poor therapeutic efficacy still pose a great challenge to [...] Read more.
Backgrounds: The rapid initiation of highly active anti-retroviral therapy (HAART) can control HIV-1 viremia and stabilize the long-term health of people living with HIV-1 (PLWH). Despite this, individuals who are diagnosed late and exhibit poor therapeutic efficacy still pose a great challenge to global HIV management. To address this, we conducted comprehensive multiparametric immune profiling and analyzed its association with disease progression and therapeutic efficacy. Methods: Multicolor flow cytometry was used to characterize the circulating immune cell composition and cellular phenotypes in 40 treatment-naive individuals (16 chronic, 24 newly diagnosed), 26 HAART-treated individuals, and 18 healthy controls. Comparative analyses of T cell subsets, immune activation markers, and viral load signatures were performed, followed by network construction. We carried out principal component analysis and displayed the data by dimensionality reduction. Results: Persistent immune activation, dysregulated regulatory immunity, and aberrant memory differentiation markers were identified in T cells of HIV-1-infected individuals and were associated with disease progression. Additionally, HAART-treated patients which did not fully restore CD4 T cells exhibited higher levels of activated markers, suggesting possible biomarkers of therapeutic efficacy. Conclusions: This study describes changes in immune cell profiles throughout HIV-1 disease progression and explores suitable laboratory predictors for future clinical and therapeutic settings by monitoring pathological immune cell events. Full article
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18 pages, 4408 KB  
Article
Capturing the Heterogeneity of the PDAC Tumor Microenvironment: Novel Triple Co-Culture Spheroids for Drug Screening and Angiogenic Evaluation
by Ruben Verloy, Angela Privat-Maldonado, Jonas Van Audenaerde, Sophie Rovers, Hannah Zaryouh, Jorrit De Waele, Delphine Quatannens, Dieter Peeters, Geert Roeyen, Christophe Deben, Evelien Smits and Annemie Bogaerts
Cells 2025, 14(6), 450; https://doi.org/10.3390/cells14060450 - 18 Mar 2025
Cited by 7 | Viewed by 2687
Abstract
Pancreatic ductal adenocarcinoma (PDAC) presents significant treatment challenges due to its desmoplastic reaction, which impedes therapeutic effectiveness, highlighting the need for advanced vitro models to better mimic the complex tumor environment. The current three-dimensional co-culture models of fibroblasts and endothelial cells are lacking, [...] Read more.
Pancreatic ductal adenocarcinoma (PDAC) presents significant treatment challenges due to its desmoplastic reaction, which impedes therapeutic effectiveness, highlighting the need for advanced vitro models to better mimic the complex tumor environment. The current three-dimensional co-culture models of fibroblasts and endothelial cells are lacking, which presents a challenge for performing more comprehensive in vitro research. Our study developed triple co-culture spheroid models using MiaPaCa-2 and BxPC-3 cancer cell lines, with RLT-PSC and hPSC21 pancreatic stellate cell lines and the endothelial cell line HMEC-1. These models were assessed through growth assays, multicolor flow cytometry to optimize cell ratios, cell viability assays to evaluate drug responses, and a tube formation assay with a spheroid-conditioned medium to examine angiogenesis. Our triple co-culture spheroids effectively replicate the PDAC microenvironment, showing significant variations in drug responses influenced by cellular composition, density, and spatial arrangement. The tube formation assay showcased the potential of our models to quantitatively assess a treatment-induced angiogenic response. These cost-effective triple-co-culture in vitro spheroid models provide vital insights into the PDAC microenvironment, significantly improving the quality of the in vitro evaluation of treatment responses. Full article
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14 pages, 4343 KB  
Article
Characterization of a Natural Accession of Elymus sibiricus with In Situ Hybridization and Agronomic Evaluation
by Yizhuo Liu, Jiarui Ding, Chunfei Wu, Weiwei Song, Xinyu Zhao, Haibin Zhao, Yunfeng Qu, Hui Jin, Rui Zhang, Mingyao Li, Xinyu Yan, Liangyu Zhu, Yaqi Bao, Dianhao Liu, Xinling Li, Lei Cui, Hongjie Li and Yanming Zhang
Plants 2025, 14(1), 75; https://doi.org/10.3390/plants14010075 - 29 Dec 2024
Cited by 1 | Viewed by 1277
Abstract
Elymus sibiricus, valued for its perennial nature, broad adaptability, strong cold tolerance, and high economic value in forage production, plays a crucial role in combating grassland degradation, desertification, and salinization. Using morphological and cytogenetic methods, this study evaluated the cold tolerance, post-harvest [...] Read more.
Elymus sibiricus, valued for its perennial nature, broad adaptability, strong cold tolerance, and high economic value in forage production, plays a crucial role in combating grassland degradation, desertification, and salinization. Using morphological and cytogenetic methods, this study evaluated the cold tolerance, post-harvest regeneration capacity, and perennial characteristics of the E. sibiricus accession 20HSC-Z9 in the Harbin region of China from 2020 to 2023. This accession exhibited a germination rate of over 90% and a 100% green-up rate, with purple coleoptiles indicating its strong cold tolerance. Over the three growing seasons, 20HSC-Z9 maintained stable green-up and regeneration rates, confirming its perennial nature. Morphologically, 20HSC-Z9 had an average tiller count ranging from 56 to 74, similar to that of the control accession 20HSC-ES, and its plant height was significantly lower than that of 20HSC-IWG. Furthermore, 20HSC-Z9 produced over 100 grains per spike, with a seed setting rate exceeding 90%, and a thousand-grain weight comparable to that of 20HSC-IWG. The grain protein content of 20HSC-Z9 reached a maximum of 21.19%, greater than that of the control accessions (15.6% and 18.5%). Chromosome composition analysis, using sequential multicolor genomic in situ hybridization and multicolor fluorescence in situ hybridization, confirmed the StStHH genomic constitution of 20HSC-Z9 and revealed translocations between the St and H subgenome chromosomes. These results suggest that 20HSC-Z9 has significant potential as a new perennial forage grass germplasm for cold regions, suitable for further domestication and breeding efforts. Full article
(This article belongs to the Section Plant Genetics, Genomics and Biotechnology)
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7 pages, 656 KB  
Brief Report
Immune Cell Distributions in the Blood of Healthy Individuals at High Genetic Risk of Parkinson’s Disease
by Laura Deecke, David Goldeck, Olena Ohlei, Jan Homann, Ilja Demuth, Lars Bertram, Graham Pawelec and Christina M. Lill
Int. J. Mol. Sci. 2024, 25(24), 13655; https://doi.org/10.3390/ijms252413655 - 20 Dec 2024
Cited by 3 | Viewed by 1173
Abstract
The immune system likely plays a key role in Parkinson’s disease (PD) pathophysiology. Thus, we investigated whether immune cell compositions are already altered in healthy individuals at high genetic risk for PD. We quantified 92 immune cell subtypes in the blood of 442 [...] Read more.
The immune system likely plays a key role in Parkinson’s disease (PD) pathophysiology. Thus, we investigated whether immune cell compositions are already altered in healthy individuals at high genetic risk for PD. We quantified 92 immune cell subtypes in the blood of 442 individuals using multicolor flow cytometry. Polygenic risk scores (PGS) for PD were calculated based on genome-wide significant SNPs (n = 87) from a large genome-wide association study (n = 1,530,403). Linear regression analyses did not reveal significant associations between PGS and any immune cell subtype (FDR = 0.05). Nominally significant associations were observed for NKG2C+ B cells (p = 0.026) in the overall sample. Older participants at increased genetic PD risk also showed a higher proportion of myeloid dendritic cells (p = 0.019) and CD27+CD4+ memory T cells (p = 0.043). Several immune cells were nominally statistically associated in women only. These findings suggest that major alterations of immune cells only occur later in the progression of PD. Full article
(This article belongs to the Special Issue Genomics in Neurodegenerative Diseases)
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9 pages, 4793 KB  
Review
“Chasing Rainbows” Beyond Kaposi Sarcoma’s Dermoscopy: A Mini-Review
by Emmanouil Karampinis, Olga Toli, Georgia Pappa, Anna Vardiampasi, Melpomeni Theofili, Efterpi Zafiriou, Mattheos Bobos, Aimilios Lallas, Elizabeth Lazaridou, Biswanath Behera and Zoe Apalla
Dermatopathology 2024, 11(4), 333-341; https://doi.org/10.3390/dermatopathology11040035 - 25 Nov 2024
Cited by 4 | Viewed by 2642
Abstract
The dermoscopic rainbow pattern (RP), also known as polychromatic pattern, is characterized by a multicolored appearance, resulting from the dispersion of polarized light as it penetrates various tissue components. Its separation into different wavelengths occurs according to the physics principles of scattering, absorption, [...] Read more.
The dermoscopic rainbow pattern (RP), also known as polychromatic pattern, is characterized by a multicolored appearance, resulting from the dispersion of polarized light as it penetrates various tissue components. Its separation into different wavelengths occurs according to the physics principles of scattering, absorption, and interference of light, creating the optical effect of RP. Even though the RP is regarded as a highly specific dermoscopic indicator of Kaposi’s sarcoma, in the medical literature, it has also been documented as an atypical dermoscopic finding of other non-Kaposi skin entities. We aim to present two distinct cases—a pigmented basal cell carcinoma (pBCC) and an aneurysmatic dermatofibroma—that exhibited RP in dermoscopy and to conduct a thorough review of skin conditions that display RP, revealing any predisposing factors that could increase the likelihood of its occurrence in certain lesions. We identified 33 case reports and large-scale studies with diverse entities characterized by the presence of RP, including skin cancers (Merkel cell carcinoma, BCC, melanoma, etc.), adnexal tumors, special types of nevi (blue, deep penetrating), vascular lesions (acroangiodermatitis, strawberry angioma, angiokeratoma, aneurismatic dermatofibromas, etc.), granulation tissue, hypertrophic scars and fibrous lesions, skin infections (sporotrichosis and cutaneous leishmaniasis), and inflammatory dermatoses (lichen simplex and stasis dermatitis). According to our results, the majority of the lesions exhibiting the RP were located on the extremities. Identified precipitating factors included the nodular shape, lesion composition and vascularization, skin pigmentation, and lesions’ depth and thickness. These parameters lead to increased scattering and interference of light, producing a spectrum of colors that resemble a rainbow. Full article
(This article belongs to the Special Issue Associations between Dermoscopy and Dermatopathology)
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32 pages, 24777 KB  
Article
Chemical Composition and Spectral Characteristics of Different Colored Spinel Varieties from Myanmar
by Mengwei Wang, Mingying Wang, Yihui Qi, Yuan Xue and Guanghai Shi
Minerals 2024, 14(11), 1124; https://doi.org/10.3390/min14111124 - 6 Nov 2024
Cited by 3 | Viewed by 2823
Abstract
With the growth of the Myanmar spinel market in recent years, spinels of colors other than red, including gray spinels, have gained increasing popularity. In this study, we performed conventional gemological, spectroscopic, and chemical analyses on the less commonly studied gray, red, pink, [...] Read more.
With the growth of the Myanmar spinel market in recent years, spinels of colors other than red, including gray spinels, have gained increasing popularity. In this study, we performed conventional gemological, spectroscopic, and chemical analyses on the less commonly studied gray, red, pink, and purple spinels from Mogok in Myanmar to investigate their chemical composition and color mechanisms. The Raman and FTIR spectral analyses indicated that the samples contained oxides of Mg-Al end-members and that the spectral peak positions of different colors were essentially the same. According to the major, minor, and trace elements of samples determined via EPMA and LA-ICP-MS, the purple and gray samples had the most prominent Fe contents, the red spinels had the highest Cr contents, and the pink samples had high V+Cr contents, with a certain amount of Fe. The UV–visible spectra indicated that the absorption spectrum of the gray samples was predominantly influenced by the Fetot content, particularly Fe2+. The color rendering of the purple spinels was also intimately associated with Fe. The absorption spectrum of the gray spinels was weaker but more concentrated at 458 nm than that of the purple varieties. Cr3+ and V3+ in the red spinels produced broad bands near 400 nm and 540 nm, respectively, while light pink spinels exhibited Cr3+ and V3+ absorption spectra but featured an additional absorption band at 460 nm due to Fe. This study complements other research on the coloration mechanisms of multi-color spinels from Mogok, especially gray spinels. Full article
(This article belongs to the Special Issue Gem Deposits: Mineralogical and Gemological Aspects, 2nd Edition)
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9 pages, 2549 KB  
Article
Phototuning of Multi-Color Emission in PMMA Composite Films for Information Encryption Applications
by Guang Chen, Dongxue Han, Songya Cui and Liang Peng
Coatings 2024, 14(11), 1360; https://doi.org/10.3390/coatings14111360 - 25 Oct 2024
Cited by 1 | Viewed by 1120
Abstract
A strategy centered on dynamically tunable excited-state proton transfer (ESPT) processes is proposed for the design and synthesis of luminescent compounds. An emitter based on guanidine-substituted 1,8-naphthalimide (R-1) with ESPT characteristics has been meticulously engineered. Upon incorporation into poly (methyl methacrylate) (PMMA) matrices, [...] Read more.
A strategy centered on dynamically tunable excited-state proton transfer (ESPT) processes is proposed for the design and synthesis of luminescent compounds. An emitter based on guanidine-substituted 1,8-naphthalimide (R-1) with ESPT characteristics has been meticulously engineered. Upon incorporation into poly (methyl methacrylate) (PMMA) matrices, the tunable ESPT process, transitioning between blue and yellow-green emission within the composite film, can be precisely controlled through irradiation in different pH environments. Moreover, the luminescence of the R-1/PMMA composite film exhibits variations in response to environmental changes, and demonstrates excellent fatigue resistance. Exploiting this characteristic, information such as “2020” can be encoded, and this encoded information automatically manifests in response to fluctuations in external pH. Specifically, employing a designated method is essential for accurately deciphering the information. The pH-dependent nature of this feature imparts a higher level of security to the material and offers new insights into information encryption. Full article
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12 pages, 4907 KB  
Article
Multi-Wavelength Excitable Multicolor Upconversion and Ratiometric Luminescence Thermometry of Yb3+/Er3+ Co-Doped NaYGeO4 Microcrystals
by Hui Zeng, Yangbo Wang, Xiaoyi Zhang, Xiangbing Bu, Zongyi Liu and Huaiyong Li
Molecules 2024, 29(20), 4887; https://doi.org/10.3390/molecules29204887 - 15 Oct 2024
Viewed by 1352
Abstract
Excitation wavelength controllable lanthanide upconversion allows for real-time manipulation of luminescent color in a composition-fixed material, which has been proven to be conducive to a variety of applications, such as optical anti-counterfeiting and information security. However, current available materials highly rely on the [...] Read more.
Excitation wavelength controllable lanthanide upconversion allows for real-time manipulation of luminescent color in a composition-fixed material, which has been proven to be conducive to a variety of applications, such as optical anti-counterfeiting and information security. However, current available materials highly rely on the elaborate core–shell structure in order to ensure efficient excitation-dependent energy transfer routes. Herein, multicolor upconversion luminescence in response to both near-infrared I and near-infrared II (NIR-I and NIR-II) excitations is realized in a novel but simple NaYGeO4:Yb3+/Er3+ phosphor. The remarkably enhanced red emission ratio under 1532 nm excitation, compared with that under 980 nm excitation, could be attributed to the Yb3+-mediated cross-relaxation energy transfers. Moreover, multi-wavelength excitable temperature-dependent (295–823 K) upconversion luminescence realizes a ratiometric thermometry relying on the thermally coupled levels (TCLs) of Er3+. Detailed investigations demonstrate that changing excitation wavelength makes little difference for the performances of TCL-based ratiometric thermometry of NaYGeO4:Yb3+/Er3+. These findings gain more insights to manipulate cross-relaxations for excitation controllable upconversion in single activator doped materials and benefit the cognition of the effect of excitation wavelength on ratiometric luminescence thermometry. Full article
(This article belongs to the Special Issue Rare Earth Based Luminescent Materials)
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12 pages, 5496 KB  
Article
Effect of Polymer Encapsulation on the Mechanoluminescence of Mn2+-Doped CaZnOS
by Xiaohan Wu, Mengmeng Cao, Congcong Han, Jinyi Zhang, Xiangrong Li and Jieqiong Wan
Polymers 2024, 16(17), 2389; https://doi.org/10.3390/polym16172389 - 23 Aug 2024
Cited by 2 | Viewed by 4367
Abstract
Rare earth and transition metal ion-doped CaZnOS has garnered significant attention for its exceptional mechanoluminescence (ML) performance under mild mechanical stimuli and its capability for multicolor emissions. Since powdered phosphors are not directly usable, they require encapsulation within with polymers to create stable [...] Read more.
Rare earth and transition metal ion-doped CaZnOS has garnered significant attention for its exceptional mechanoluminescence (ML) performance under mild mechanical stimuli and its capability for multicolor emissions. Since powdered phosphors are not directly usable, they require encapsulation within with polymers to create stable structures. This study investigates Mn2+-doped CaZnOS (CaZnOS:Mn2+) as the ML phosphor, optimizing its performance by varying the Mn2+ content, resulting in bright orange-red emissions from the d-d transitions of the Mn2+ activator. A quantum efficiency of 59.08% was achieved through the self-sensitization of the matrix lattice and energy transfer to the Mn2+ luminescent centers. The enhancement in ML due to Mn2+ doping is attributed to the reduced trap depth and increased trap concentration. Encapsulation with four polymers—PDMS, PU, SIL, and RTV-2—was explored to further optimize ML performance. Among these, PDMS provides the best ML output and sensitivity, owing to its slightly cross-linked structure and good triboelectric properties. The optimized CaZnOS:0.03Mn2+/PDMS composite, featuring excellent flexibility and recoverability, shows great potential for applications in anti-counterfeiting encryption, stress sensors, and wearable devices. Full article
(This article belongs to the Section Polymer Applications)
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