Change In Color Research Articles

Real-Time Monitoring of Adsorption-Induced Scrolling of Colloidal Inorganic Nanosheets.

Inorganic nanotubes have attracted much attention due to their unique physicochemical properties. Nanotubes can be prepared by scrolling exfoliated nanosheets under ambient conditions. However, how the nanosheet scrolled in its colloidal state has not been experimentally visualized. In this paper, we directly observed the scrolling process of nanosheets upon adsorption of organic cations. Exfoliated flat nanosheets of niobate and clay in aqueous colloids were found to scroll by adding organic cations, such as exfoliation reagents, to the colloids. Employment of cationic stilbazolium dye enabled in situ observation of the dye adsorption and scrolling by optical microscopy based on changes in color and morphology of the nanosheets. The scrolling was promoted for nanosheets adsorbed with a stilbazolium dye with a longer alkyl chain, suggesting that the interaction between the hydrophobic parts of the dye cations is the driving force of the scrolling. This finding should encourage research on the formation of nanotubes from nanosheets and also provides important guidelines for the selection of appropriate exfoliation reagents when exfoliating nanosheets from layered crystals.

New gas sensitive films containing anthocyanin/curcumin for real-time monitoring of strawberries quality

Gas sensitive films (GSFs) of polyvinyl alcohol (PA), soluble starch (SS), and polyethylene glycol bis (3-aminopropyl) ether (PGE) containing blueberry anthocyanin (BA), curcumin (CU), and anthocyanin/curcumin complexes were created to monitor the quality changes of strawberries during storage (room temperature, 24 ± 2 °C). Using headspace-gas chromatography-mass spectrometry (HS-GC-MS), the volatile aroma gases released during storage of strawberries were analyzed. Results showed that the release of aldehydes was more closely associated to the quality of the strawberries. The BA, CU and BA/CU complexes (mass ratio: 1:2 and 2:1) were well dispersed in GSFs and improved the films' hydrophilicity, however, there was no effect on the water vapor permeability. The four GSFs were employed to monitor strawberry quality changes over the course of storage. The results showed that the changes in color of the four GSFs had a strong correlation with the quality of strawberries, which could be classified as fresh, sub-fresh and spoiled.

Anti-Cracking TEOS-Based Hybrid Materials as Reinforcement Agents for Paper Relics.

Tetraethoxysilane (TEOS) is the most commonly used silicon-based reinforcement agent for conserving art relics due to its cost-effectiveness and commercial maturity. However, the resulting silica gel phase is prone to developing cracks as the gel shrinks during the sol-gel process, potentially causing severe damage to the objects being treated. In this study, dodecyltrimethoxysilane (DTMS) was introduced into TEOS to minimize this shrinkage by adding elastic long chains to weaken the capillary forces. The gel formed from the DTMS/TEOS hybrid material was transparent and crack-free, featuring a dense microstructure without mesopores or micropores. It exhibited excellent thermal stability, with a glass transition temperature of up to 109.64 °C. Evaluation experiments were conducted on artificially aged, handmade bamboo paper. The TEOS-based hybrid material effectively combined with the paper fibers through the sol-gel process, polymerizing into a network structure that enveloped the paper surface or penetrated between the fibers. The surface of the treated paper displayed excellent hydrophobic properties, with no significant changes in appearance, color, or air permeability. The mechanical properties of the treated bamboo paper improved significantly, with longitudinal and transverse tensile strengths increasing by up to 36.63% and 44.25%, respectively. These research findings demonstrate the promising potential for the application of DTMS/TEOS hybrid materials in reinforcing paper relics.

Fluorescence-enhanced Cs2Ag0.3-xNaxZn0.35In1-yCl6:yM double perovskites for multimodal optical anti-counterfeiting

The excellent optical properties of lead-free halide double perovskites (LHDPs) Cs2AgInCl6 are of great importance in the field of anti-counterfeiting encryption. However, the fluorescence quantum yield of the existing Cs2AgInCl6-based materials is relatively low, and the fluorescence color is monochromatic, making it difficult to use in advanced multi-mode anti-counterfeiting applications. In this study, we synthesized Cs2Ag0.3-xNaxZn0.35In1-yCl6:yM (M = Cr/Bi) series LHDPs using an anti-solvent assisted co-precipitation method, improving the optical properties of Cs2AgInCl6-based materials by optimizing their composition. The fluorescence quantum yield of Zn–Na substituted Cr-doped Cs2Ag0.3-xNaxZn0.35In1-yCl6 LHDPs increased from 1.53 % to 82.57 % on the basis of Cs2AgInCl6. The Zn–Na substituted Bi-doped Cs2Ag0.3-xNaxZn0.35In1-yCl6 LHDPs exhibited dual-wavelength fluorescence emission at 407 and 650 nm, and the relative intensity between the two emission wavelengths changed via a change in the Bi doping amount, resulting in a change in the material's luminescence color. The as-synthesized LHDPs could be applied to multi-mode anti-counterfeiting, optical coding information storage, and art decoration applications.

Effect of Storage on the Antioxidant, Color and Sensory Properties of Local Bread

The aim of this study is to evaluate the effect of storage on antioxidant, color and sensory properties of bread, containing sourdough and potato puree, baked in stone oven in Afyonkarahisar which is city of Turkey. Sourdough was used as yeast for the production of bread. Potato puree was added to the formulation at the ratio of 30%. Breads were stored in sealed polyethylene bag at room temperature (20°C) for 1, 5 and 10 days. Bread characterization, color, β-carotene, phenolics, minerals were analyzed and a sensory evaluation was performed. Decrease in bread mass, height, width, crust thickness, total volume and specific volume were observed. β-carotene and phenolic compounds quantity of breads decreased with increasing of storage time. Storage caused a change in the crumb color of breads. Storage statistically didn’t affect the crust color values of breads. According to the panelist scores, it can be concluded that all breads stored 1, 5 and 10 days had a desired crust color, crumb texture, porosity, aroma and overall acceptance.

Translucency and Color Difference of Monolithic Zirconia Restorations: The Effect of Surface Finishing on Background Color

Aim: This study evaluates the effect of different surface finishing procedures on the color and translucency values of monolithic zirconia materials on three different colored composite backgrounds. Materials and Methods: Sixty monolithic zirconia blocks of three different translucency levels were prepared in vitro using computer-aided design/computer-aided manufacturing (CAD/CAM) systems. The correlation between repeat measurements was 0.5, resulting in a sample size of nine samples per group to detect a medium effect size, f = 0.25. Half of the zirconia blocks in each group were subjected to glazing, while the other half were polished ( n = 10). Composite blocks of three different colors were prepared to simulate dental substrates, and the zirconia specimens were placed on these composite backgrounds. The color parameters of the specimens were measured using a spectrophotometer on gray, black, and white backgrounds. Three-way repeated measure ANOVA was used to assess the interaction between the three independent variables (zirconia brand, surface finishing technique, and background color) and the effects of each tested variable on the changes in color and translucency. Results: The surface finishing techniques had a significant effect on the color and translucency of the monolithic zirconia materials. Glazing resulted in higher color differences and lower translucency values compared to polishing. For backgrounds of the same color, no significant differences were detected between the glazed zirconia groups for the same condition ( p > .016). Conclusion: Overall, the study demonstrated the importance of selecting the appropriate surface finishing technique and translucency property of the monolithic zirconia materials to obtain the optimal esthetic results in dental restorations.

Effect of superheated steam treatment on enzyme inactivation, morphostructural, physicochemical and digestion properties of sand rice (Agriophyllum squarrosum) flour

The lipase (LA) and peroxidase (POD) activities, as well as morphological structure, physicochemical and digestion properties of sand rice flour (SRF) treated with superheated steam (SS), were investigated. SS treatment at 165 °C completely deactivated LA and resulted in a 98% deactivation of POD activities in SRF. This treatment also intensified gelatinization, induced noticeable color alterations, and decreased pasting viscosities. Furthermore, there was a moderate reduction in crystal structure, lamellar structure, and short-range ordered structure, with a pronounced reduction at temperatures exceeding 170 °C. These alterations significantly impacted SRF digestibility, leading to increased levels of rapidly digestible starch (RDS) and resistant starch (RS), with the highest RS content achieved at 165 °C. The effectiveness of SS treatment depends on temperature, with 165 °C being able to stabilize SRF with moderate changes in color and structure. These findings will provide a scientific foundation for SS applicated in SRF stabilization and modification.

Axillar chylous fistula, a rare complication after axillary lymph node dissection

Background: Chylous fistulas following axillary surgery represent a rare, but significant complication, with a limited number of reported cases in the existing literature. Therefore, there is no consensus or a clinical guideline regarding the management of this condition [1]. Case description: A 67-year-old female, with no relevant medical history, after diagnosis of breast cancer (luminal B Her2-negative invasive ductal carcinoma, cT2N2M0) underwent surgical intervention involving left breast-conserving surgery and left axillary lymph node dissection. On the fifth day postoperative, a change in the drainage color and an increase in its volume were observed. Axillary chylous fistula was then clinically suspected, so a biochemical analysis of the drainage was request. The presence of triglycerides confirmed the diagnosis. A conservative approach was adopted, incorporating a low-fat diet and medical treatment with octreotide. Resolution ensued after 13 days of treatment, facilitating the patient’s discharge on the 18th postoperative day.

Dehydration, Rehydration and Thermal Treatment: Effect on Bioactive Compounds of Red Seaweeds Porphyra umbilicalis and Porphyra linearis.

The nutritional and bioactive value of seaweeds is widely recognized, making them a valuable food source. To use seaweeds as food, drying and thermal treatments are required, but these treatments may have a negative impact on valuable bioactive compounds. In this study, the effects of dehydration, rehydration, and thermal treatment on the bioactive compounds (carotenoids, phycobiliproteins, total phenolic content (TPC), total flavonoids content (TFC)), antioxidant (ABTS and DPPH radical scavenging activities) and anti-Alzheimer's (Acetylcholinesterase (AchE) inhibitory activities, and color properties of Porphyra umbilicalis and Porphyra linearis seaweeds were evaluated. The results revealed significant reductions in carotenoids, TPC, TFC, and antioxidant activities after the seaweeds' processing, with differences observed between species. Thermal treatment led to the most pronounced reductions in bioactive compound contents and antioxidant activity. AchE inhibitory activity remained relatively high in all samples, with P. umbilicalis showing higher activity than P. linearis. Changes in color (ΔE) were significant after seaweeds' dehydration, rehydration and thermal treatment, especially in P. umbilicalis. Overall, optimizing processing methods is crucial for preserving the bioactive compounds and biological activities of seaweeds, thus maximizing their potential as sustainable and nutritious food sources or as nutraceutical ingredients.

Pengaruh Penambahan Ampas Kopi Sebagai Adsorben Pada Limbah Cair Tenun Ikat

Synthetic dyes contain naphthol dyes, one of which contains Cr metal. tie woven wastewater treatment can be carried out using adsorption methods, one of which is using activated charcoal. This study aims to determine the effect of using coffee grounds as an adsorbent on woven textile waste. The method in this study is an experimental method in the form of Posttest Only Control Group Design. The test parameters include the degree of acidity (pH), organoleptic test, and Chromium (Cr) content test. The results showed that the pH test before contact with activated charcoal had a pH value of 5 (acid), after contact with activated charcoal the pH value became 7 (neutral). Thus, the pH value can be said to meet the quality standards of tie-weaving liquid waste. Meanwhile, in organoleptic testing, there was a change in color from black waste to clear yellow. Whereas in testing the Cr level before contact with activated charcoal reached 4.60 mg/l after the addition of a dose of activated charcoal the Cr level decreased to 0.46 mg/l, 0.22 mg/l, and 0.38 mg/l. The effectiveness of the adsorbent ability of the Cr content test in each treatment (P1, P2, P3), still meets the requirements for the quality standard of woven textile wastewater from Cr metal dyes, SNI No 06-6989-22-2004, it can be concluded that the addition of coffee grounds has an effect on of textile woven wastewater.

Clinical and radiographic characterization of external root resorption.

The following bibliographic review was carried out with the purpose of recognizing the clinical and radiographic characteristics that must be considered in the diagnosis of external root resorption, including treatments. A bibliographic search was carried out in PubMed/Medline, Cochrane Library and Google Scholar databases under the term "external root resorption", from 2010 to 2022 in Spanish and English. Experimental studies and bibliographic reviews were selected, and finally 17 articles were included. The results obtained indicated that each type of resorption presents specific clinical characteristics that differentiate them, these are: for external inflammatory resorption a negative pulp vitality; for replacement external resorption the absence of mobility and metallic percussion; for cervical external resorption a pink coloration of the crown; superficial external resorption does not present any type of clinical symptoms and transient apical collapse presents a transient change in color. External root resorptions require accurate and early diagnosis. A clinical examination should be performed with emphasis on the following: probing, coloration, mobility, and vitality tests.

Integrating PEGylated peptide-oriented bacteria-imprinted matrix and PdPt bimetallic-doped imidazolium zeolite framework-8 for sensitive detection of Escherichia coli with smartphone readout system

Escherichia coli (E. coli) is one of the major foodborne pathogens, and its efficient isolation and detection from complex samples are crucial. Herein, we fabricated a novel hydrophilic-PEGylated peptide-oriented bacteria-imprinted PDMS matrix (HPBIM) for highly efficient capture of E. coli from complex samples. The antibody-free HPBIM possessed a hierarchical structure of imprinted cavities, which were inlaid with peptide-functionalized SiO2 (SiO2@peptide). Meanwhile, PEGylation was performed on the non-imprinted region of HPBIM to limit the non-specific absorption. So HPBIM could specifically capture target E. coli due to the synergistic effect of peptide affinity, bacteria-imprinting and PEGylation of non-imprinted region. Additionally, a new polyethylene glycol-covered / boronic acid-modified PdPt bimetallic-doped ZIF-8 (PBPPZ) was prepared for electively labeling E. coli captured by HPBIM. PBPPZ exhibited excellent peroxidase-like activity and could generate sensitive output signals, which could be further quantitatively determined by smartphone readout device. To prove the practicability, we proposed an innovative HPBIM-PBPPZ strategy, in which the HPBIM first selectively captured E. coli, then the PBPPZ specific labeled E. coli and oxidized colorless substrate into colored product, and finally the change in color was quantitatively determined by a smartphone readout device equipped with a Color Grab APP. The biomacromolecule-free HPBIM-PBPPZ strategy exhibited excellent sensitivity with limit of detection of 69 CFU mL−1 for grapefruit juice and 257 CFU mL−1 for milk, and was successfully applied in the determination of E. coli in spiked sample with recovery and relative standard deviation in the range of 88.1–106.7% and 4.0–7.8%, respectively. Therefore, we believe that the HPBIM-PBPPZ strategy has great potential to become a powerful tool for the ultrasensitive detection of pathogens in complex biological samples.

Amplifying Photon Upconversion in Alloyed Nanoparticles for a Near-Infrared Photodetector.

Photon upconverison has attracted a substantial amount of interest in diverse fields due to its characteristic anti-Stokes emissions. However, obtaining intense emission under low-power laser irradiation has remained a challenge. Here we report a mechanistic design of activator-sensitizer alloyed nanoparticles to achieve bright upconversion under weak infrared irradiation. This design allows a nearest sensitizer-activator separation to facilitate efficient energy transfer that results in remarkably enhanced upconversion (>2 orders of magnitude) under 0.26 W cm-2 irradiation compared to that of the Er sublattice, and the upconversion quantum yield also shows a 20-fold increase. Interestingly, the alloyed nanoparticles exhibit a gradual change in emission color with an increase in Yb3+ content, and moreover, their emission colors can be dynamically controlled by simply modulating the excitation laser power and pulse widths. Such alloyed nanoparticles show great promise for application in a near-infrared photodetector.

Secure Pixel-Level Data Concealment: A Novel Approach for Securing Black and White Images within Color Images

In the era of rampant digital data transfer, concerns regarding the secure and reliable transmission of information persist, with numerous attempts at concealing and transporting data globally. Despite the plethora of existing techniques, issues persist, ranging from misinterpretation to malicious misuse of data during the transfer process. To address some of these challenges, this research introduces an innovative method centered on the modification of pixel data to embed concealed information. The primary objective is to alter pixel values in a manner that accommodates the storage of data pertaining specifically to black and white image pixel data. The proposed technique is designed to exclusively encode information related to two-pixel values, with careful adjustments made to ensure the masked image remains non-deceptive. Pixel values undergo subtle alterations to mitigate susceptibility issues associated with corner values, particularly at the border values of 254 and 255 for RGB values. The developed method presents a simplified yet robust data hiding technique, allowing the storage of black and white images within color images while achieving a high Peak Signal-to-Noise Ratio (PSNR) compared to standard ".png" images. Crucially, the developed approach addresses the challenge of minimizing drastic changes in pixel color, enhancing the overall fidelity of the stego image. Furthermore, the versatility of the proposed method is showcased by its potential to accommodate more than three images when the stego image size is appropriately large and segmented. A practical and efficient solution has been contributed to the persistent issues associated with secure data transfer, presenting a novel methodology for concealing black and white images within color images.

Eye-Readable and Wearable Colorimetric Sensor Arrays for In Situ Monitoring of Volatile Organic Compounds.

Wearable sensors utilize changes in color as a response to physiological stimuli, making them easily recognizable by the naked eye. These colorimetric wearable sensors offer benefits such as easy readability, rapid responsiveness, cost-effectiveness, and straightforward manufacturing techniques. However, their applications in detecting volatile organic compounds (VOCs) in situ have been limited due to the low concentration of complex VOCs and complicated external interferences. Aiming to address these challenges, we introduced readable and wearable colorimetric sensing arrays with a microchannel structure and highly gas-sensitive materials for in situ detection of complex VOCs. The highly gas-sensitive materials were designed by loading gas-sensitive dyes into the porous metal-organic frameworks and further depositing the composites on the electrospun nanofiber membrane. The colorimetric sensor arrays were fabricated using various gas-sensitive composites, including eight dye/MOF composites that respond to various VOCs and two Pd2+/dye/MOF composites that respond to ethylene. This enables the specific recognition of multiple characteristic VOCs. A microfluidic channel made of polydimethylsiloxane (PDMS) was integrated with different colorimetric elements to create a wearable sensor array. It was attached to the surface of fruits to collect and monitor VOCs using the DenseNet classification method. As a proof of concept, we demonstrated the feasibility of the wearable sensing system in monitoring the ripening process of fruits by continuously measuring the VOC emissions from the skin of the fruit.

Recombinase-Aided Loop-Mediated Isothermal Amplification on Human Plasmodium knowlesi.

Loop-mediated isothermal amplification (LAMP) is a nucleic acid amplification technique that can amplify specific nucleic acids at a constant temperature (63-65°C) within a short period (<1 hour). In this study, we report the utilization of recombinase-aided LAMP to specifically amplify the 18S sRNA of Plasmodium knowlesi. The method was built on a conventional LAMP assay by inclusion of an extra enzyme, namely recombinase, into the master mixture. With the addition of recombinase into the LAMP assay, the assay speed was executed within a time frame of less than 28 minutes at 65°C. We screened 55 P. knowlesi samples and 47 non-P. knowlesi samples. No cross-reactivity was observed for non-P. knowlesi samples, and the detection limit for recombinase-aided LAMP was one copy for P. knowlesi after LAMP amplification. It has been reported elsewhere that LAMP can be detected through fluorescent readout systems. Although such systems result in considerable limits of detection, the need for sophisticated equipment limits their use. Hence, we used here a colorimetric detection platform for the evaluation of the LAMP assay's performance. This malachite green-based recombinase-aided LAMP assay enabled visualization of results with the naked eye. Negative samples were observed by a change in color from green to colorless, whereas positive samples remained green. Our results demonstrate that the LAMP assay developed here is a convenient, sensitive, and useful diagnostic tool for the rapid detection of knowlesi malaria parasites. This method is suitable for implementation in remote healthcare settings, where centralized laboratory facilities, funds, and clinicians are in short supply.

Hymenaea courbaril resin-mediated gold nanoparticles as catalysts in organic dyes degradation and sensors in pharmaceutical pollutants

In this study, green synthesis of gold nanoparticles (AuNPs) using aqueous extract from Hymenaea courbaril resin (HCR) is reported. The successful formation, functional group involvement, size, and morphology of the subject H. courbaril resin mediated gold nanoparticles (HCRAuNPs) were confirmed by Ultra Violet-Visible (UV–vis) spectroscopy, Fourier-Transform Infrared spectroscopy (FTIR), and Transmission Electron Microscopy (TEM) techniques. Stable and high yield of HCRAuNPs was formed in 1:15 (aqueous solution: salt solution) reacted in sunlight as indicated by the visual colour change and appearance of surface Plasmon resonance (SPR) at 560 nm. From the FT-IR results, the phenolic hydroxyl (–OH) functional group was found to be involved in synthesis and stabilization of nanoparticles. The TEM analysis showed that the particles are highly dispersed and spherical in shape with average size of 17.5 nm. The synthesized HCRAuNPs showed significant degradation potential against organic dyes, including methylene blue (MB, 85 %), methyl orange (MO, 90 %), congo red (CR, 83 %), and para nitrophenol (PNP, 76 %) up to 180 min. The nanoparticles also demonstrated the effective detection of pharmaceutical pollutants, including amoxicillin, levofloxacin, and azithromycin in aqueous environment as observable changes in color and UV–Vis spectral graph.

Polyurethane‐based nanocomposite for catalytic reduction of toxic dyes

AbstractIn this work, we prepared AuNPs loaded polyurethane‐sodium alginate (Au‐PU‐ALg) composite polymers by casting and in‐situ reduction method. Successful fabrication of AuNPs was confirmed by UV–visible, Fourior transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), field emission scanning elcetron microscopy (FESEM), and energy dispersive X‐ray (EDX) analysis along with the change in color of the suspension from yellow to dark purple. Thermo‐gravimetric analysis (TGA) also confirmed the loading of 7.44 % AuNPs of total nanocomposite contents. The catalytic activity of Au‐PU‐ALg nanocomposites was checked by reducing Rhodamine B (RhB) as a model reaction. It was seen that reduction of RhB was successfully done in the presence of NaBH4 and Au‐PU‐ALg nanocomposite in just 8 min with value of kapp found as 0.648 min−1. While the value of kapp for RhB reduction was found as 0.0008, 0.00221, and 0.0008 min−1 in the presence of catalyst, NaBH4 and polymer gel particles, respectively. Thus results show that the value of kapp for the reduction of RhB in the presence of NaBH4 and catalyst was found high as compared to the controlled reactions. Complex mixture of dyes such as RhB, crystal violet (CV), Congo red (CR), and dyes polluted industrial wastewater was become colorless in 10 and 3 min, respectively on mixing with catalyst and reducing agent. It was also observed that reduction of RhB followed pseudo first order kinetic model and Langmuir Hinshelwood mechanism.

Combining transfer learning and hyperspectral imaging to identify bruises of pears across different bruise types.

Mechanical bruise is one of the most crucial factors affecting the quality of pears, which has a huge influence on postharvest transportation, storage, and sale of pears. To rapidly detect early bruises of pears across different bruise types, hyperspectral imaging technology coupled with transfer learning methods was performed in this study. Two transfer learning methods, that is, transfer component analysis (TCA) and manifold embedded distribution alignment (MEDA), were applied for two tasks (impact bruise→crush bruise, crush bruise→impact bruise). Supporting vector machine (SVM) was set as a baseline to conduct analysis and comparison of the transferability of the models. The result showed that, for task 1 (impact bruise→crush bruise), MEDA and TCA-SVM model achieved a classification accuracy of 93.33% and 91.11% in target domain, individually. For task 2 (crush bruise→impact bruise), MEDA and TCA-SVM model achieved an accuracy of 88.89% and 85.19% in target domain, respectively. Both the two models improved the accuracy compared with SVM models (84.44% for task 1; 77.04% for task 2). Overall, the results indicated that transfer learning approaches could perform pear bruise detection across different bruise types. Hyperspectral imaging in combination with transfer learning methods is a promising possibility for the efficient and cost-saving field detection of fruit bruises among different bruise types. PRACTICAL APPLICATION: The production and export of pears are faced with problems of mechanical damage due to vibration, collision, impact, and other factors, which cause chemical changes in color, odor, and taste. Sometimes the bruise was too slight to be ignored which would infect with other fruits in the future. In this study, we used hyperspectral imaging combined with transfer learning method could detect these slight bruises caused by different factors. Distinguishing different types of damage can provide a reference for quick judgment of the process causing damage and take prompt measures to reduce economic losses.

Effect of long-term high-temperature exposure in a controlled atmosphere on mullite-corundum ceramics for advanced applications in nuclear power technology

This work investigates the behavior and properties of corundum and mullite ceramics at high temperatures and during very long exposures in a controlled atmosphere. The motivation of the work lies primarily in advanced applications in nuclear energy technology, specifically in the search for materials for helium-cooled reactors of the 4th generation. The studied ceramic samples Al63, Al70, Al76, Al96, Al100, where the number indicates the mass percentage of Al2O3, were exposed for 1000 h at a temperature of 900 °C in gaseous atmospheres of helium, nitrogen and air. The properties of the exposed and unexposed samples were evaluated by measuring the bending strength at room temperature (CMOR), hot modulus of rupture at high temperature (HMOR), and isothermal creep, BET method, and using electron microscopy. The color changes induced by the reducing atmosphere and temperature were also interpreted using a simple thermochemical model. The CMOR measurement results show that all ceramic samples do not significantly change their properties due to long-term exposure. The detected deviations in the exposed samples from the unexposed ones can be considered random caused by the inherent heterogeneous structure. A similar conclusion also applies in the case of the HMOR measurement results, except for the results for the Al63 sample, where the drop in the strength of the exposed samples by approx. 37 MPa (20 %) may be related with the highest proportion of polyvalent oxide admixtures of all studied ceramics, i.e. 1.01 wt % Fe2O3 and 0.52 wt % TiO2. The change in color indicates that the iron and titanium present are being reduced. However, none of the conducted experiments indicate that changes in the redox state associated with the formation of oxygen vacancies would significantly reduce strength at high temperatures or increase creep in mullite ceramics.