Search Results (170)

The prevention of biofilm formation and algal biodeterioration on building materials, particularly on cultural heritage sites, is a growing concern. Due to regulatory restrictions on conventional algicidal biocides in Europe, natural alternatives such as essential oils are gaining interest for their potential use in heritage conservation. This study evaluates the anti-algal activity of Salvia officinalis and Equisetum arvense (essential oils, hydrolates, and extracts) against a mixed culture of five green algae species (Bracteacoccus minor, Stichococcus bacillaris, Klebsormidium nitens, Chloroidium saccharophilum, and Diplosphaera chodatii). The plant materials were processed using hydrodistillation and solvent extraction, followed by chemical characterization through gas chromatography–mass spectrometry (GC-MS). Biological efficacy was assessed by measuring algal growth inhibition, changes in biomass colour, chlorophyll a concentration, and fluorescence. S. officinalis yielded higher extract quantities (extraction yield: 23%) than E. arvense and contained bioactive compounds such as thujone, camphor, and cineole, which correlated with its strong anti-algal effects. The essential oil of S. officinalis demonstrated the highest efficacy, significantly inhibiting biofilm formation (zones of inhibition: 15–94 mm) and photosynthetic activity at 0.5% concentration (reduction in chlorophyll a concentration 90–100%), without causing visible discolouration of treated surfaces (∆E < 2). These findings highlight the potential of S. officinalis essential oil as a natural, effective, and material-safe algicidal biocide for the sustainable protection of cultural heritage sites. Full article

Microbial contamination is a global concern with impacts on a variety of industries ranging from marine to biomedical applications. Recent research on hydrophilic polymer-based coatings is focused on combining antifouling polymers with nanomaterials to enhance mechanical, optical, and stimuli-responsive properties, yielding colour changing, self-healing, and super hydrophilic materials. This study combines the hydrophilic and antifouling properties of vitamin B5 analogous methacrylamide (B5AMA)-based polymers with stimuli-responsive anthocyanin-dye-loaded cellulose nanocrystals (CNCs) to develop antifouling materials with colour changing capabilities upon bacterial contamination. Poly(B5AMA)-grafted CNCs were prepared through surface-initiated photoiniferter reversible addition fragmentation chain transfer (SP-RAFT) polymerization and characterized through proton nuclear magnetic resonance (¹H-NMR), transmission electron microscopy (SEM/TEM), and X-ray photon spectroscopy (XPS) to confirm the formation of surface-grafted polymer chains. The bare CNCs and poly(B5AMA)-grafted CNCs were loaded with anthocyanin dye and evaluated for pH-dependent colour changing capabilities. Interestingly, anthocyanin-loaded CNCs demonstrated vibrant colour changes in both solution and dried film form upon bacterial contamination; however, limited colour changing capabilities of the composites, specifically in dried film form, were attributed to the enhanced dispersibility and antifouling capabilities of the polymer-coated CNCs. Full article

In this study, three different detox drinks were examined for their effects on the surface roughness, colour change (∆E₀₀), and transparency parameters (∆TP₀₀) of universal resin composites. One hundred twenty samples were prepared, thirty each of universal resin composites (Omnichroma, OptiShade, Filtek Ultimate Universal, and Essentia Universal). Initial values were measured. The samples were randomly divided into three subgroups and exposed to the detox drinks. Measurements were repeated after 7, 14, and 28 days of exposure to detox drinks. The highest average surface roughness values in detox drinks were obtained with Essentia Universal. It was found that average surface roughness values increased over time, and there was a significant difference between the average surface roughness values obtained during the measurement periods (p < 0.05). In all detox drinks, the lowest ∆E₀₀ values were obtained on days 7 and 14 with OM, while the highest ∆E₀₀ values were obtained on day 28. There was a significant difference in the ∆E₀₀ values of the universal resin composites tested at each time point (p < 0.05). The highest ∆TP₀₀ values were obtained from OM in all periods and all detox drinks, while the lowest ∆TP₀₀ values were obtained from FU. When the effects of resin composites, detox drinks, and time on ∆TP₀₀ were analysed, a statistically significant difference was found (p < 0.05). Manufacturers recommend using detox drinks for 28 days. However, this period of use may affect the surface properties of restorative materials. Based on these data, we recommend careful use of detox drinks to prevent adverse effects on restorative materials. Full article

This study developed chitosan-based active edible coating formulations with antioxidant and antimicrobial properties exhibited by oregano and cinnamon leaf essential oils (EOs) to extend the shelf life of fresh-cut ‘Braeburn’ apples. The primary coating consisted of chitosan (1.5% w/v), ascorbic acid (2% w/v), and citric acid (2% w/v). Oregano (0.06 and 0.15% v/v) and cinnamon leaf (0.06 and 0.1% v/v) EOs were added to the primary coating. The coated apple slices were stored for 9 days at 4 ± 1 °C. Changes in weight loss, water activity, titratable acidity, total soluble solids content, polyphenol oxidase (PPO) activity, firmness, colour, visual appearance, surface morphology, and microbial activity were measured on days 2 and 9. The results revealed that the control samples deteriorated rapidly during storage. However, higher concentrations of EOs reduced moisture loss, water activity, and acid conversion but slightly impacted visual appearance. The coatings effectively inhibited the PPO activity through storage. The formulation with 0.1% cinnamon leaf EO may be considered a viable candidate for application as a coating material, followed by the formulation containing 0.06% oregano EO, maintaining the optimum quality parameters of fresh-cut apples. Chitosan-based coatings with added EOs can be a promising alternative for maintaining fresh-cut apple quality during storage. Full article

Thermochromic materials have attracted interest in textile applications, particularly in printing and dyeing processes. However, their thermochromic properties and impact on fabric comfort remain underexplored. This study aimed to investigate the thermochromic properties of printed fabrics with green-to-brown transitions and evaluates their comfort attributes. In the present study, a thermochromic dye paste was applied to nylon/cotton medium-weight fabric via screen printing process. The brown pigment paste was applied first, followed by the thermochromic olive green dye. The printed fabrics were tested for thermochromism, morphology, Fourier Transform Infrared Spectroscopy (FTIR), and comfort properties. Comfort properties were assessed via air permeability, water vapour permeability, and moisture management tests. The results show reversible colour changes from green (25 °C) to brown (40 °C), with increasing lightness (L*) and shifting green–red coordinates (−a*). The scanning electron microscopy (SEM) confirmed uniform dye dispersion, and the FTIR validated the presence of thermochromic pigments. The printed fabrics showed a reduction in air permeability from 40.2 mm/s to 0 mm/s, while water vapour permeability decreased by 62.50% compared to the pristine fabric due to the coating layers. The overall moisture management properties of the printed fabric remained similar to those of the unprinted fabric, with a grade of 1. These findings highlight the potential of thermochromic textiles for adaptive camouflage, particularly in military uniforms, contributing to the advancement of intelligent textiles with enhanced thermal responsiveness. Full article

The demand for polymer composite materials in the dental market is increasing every year. This rise is due to their excellent properties and ongoing technological advancements. The goal of this study was to develop new photoinitiators included in the liquid organic matrix, which is one of the main components of dental composites. Therefore, a series of compounds based on the indenoquinoxaline skeleton was synthesized, differing in the substituent. The spectroscopic properties of these compounds allowed their use as visible-light photoinitiators of radical polymerization in combination with (phenylthio)acetic acid. In addition to the polymerization kinetics, the lifetime and quantum yield of the triplet-state formation and the rate constants of its quenching by (phenylthio)acetic acid were determined. The durability of the designed composites was also assessed. Ageing tests included hydrothermal ageing, allowing for the determination of sorption, solubility, and mass change. Solutions imitating the oral cavity environment—distilled water, artificial saliva, n-heptane, and 3% acetic acid—as well as solutions containing pigments were used for these studies. Determination of the mass change and colour stability allowed for the assessment of how these materials react to long-term exposure in the oral environment. It was found that the solution simulating the natural oral environment has a significant impact on the hydrolytic stability and colour stability of the materials. Full article

The colour degradation of murals presents a significant challenge in the conservation of architectural heritage. Previous research has often concentrated on localized pigment changes while paying insufficient attention to the interaction between colour variation and indoor environmental conditions. Although non-destructive analytical techniques are widely used in heritage studies, their integrated application in combination with colourimetry has been limited, particularly in the context of Tibetan Buddhist murals in highland continental climates. This study investigates the murals of Liuli Hall in Meidai Lamasery, Inner Mongolia, as a representative case. We employed a comprehensive methodology that combines non-destructive analytical tools, gas chromatography–mass spectrometry, and quantitative colour analysis to examine pigment composition, binding material, and surface deterioration. Through joint analysis using the CIE Lab and CIE LCh colour space systems, we quantified mural colour changes and explored their correlation with material degradation and environmental exposure. The pigments identified include cinnabar, atacamite, azurite, and chalk, with animal glue and drying oils as binding materials. Colourimetric results revealed pronounced yellowing on the east and west walls, primarily caused by the ageing of organic binders. In contrast, a notable reduction in brightness on the south wall was attributed to dust accumulation. These findings support tailored conservation measures such as regular surface cleaning for the south wall and antioxidant stabilization treatments for the east and west walls. Initial cleaning efforts proved effective. The integrated approach adopted in this study provides a replicable model for mural diagnostics and conservation under complex environmental conditions. Full article

Background and Objectives: Screening, primary prevention, and the early identification of high-risk individuals are crucial for minimising the burden of cardiovascular diseases (CVDs). In this study, we aimed to evaluate the association of retinal microvascular features with myocardial dysfunction and CVD risk factors in a group of patients with significant coronary artery disease (CAD) compared to patients with newly diagnosed isolated arterial hypertension and healthy controls. Materials and Methods: We performed a single-centre cross-sectional study on 214 individuals divided into three groups: a group of 99 cases diagnosed with significant CAD, a group of 61 cases with newly diagnosed isolated arterial hypertension, and a control group of 54 cases with no confirmed cardiovascular pathology. Colour optic disc-centred retinal photographs were taken in all cases, and the following parameters were quantified using MONA REVA 3.0.0 software (VITO Health, Mol, Belgium): central retinal arteriolar equivalent, central retinal venular equivalent, arteriovenous ratio, fractal dimension, tortuosity index, and lacunarity. Univariable and multivariable statistical analyses were performed to assess changes in retinal microvascular features in CVD. Results: Dyslipidaemia (p = 0.009), systolic blood pressure (p = 0.008), and LDL cholesterol (p = 0.003) were negatively associated while left ventricular (LV) strain (0.043) was positively associated with the CRAE. In the case of the CRVE, the coronary Agatston score (p = 0.016) proved a positive and HDL cholesterol (p = 0.018) a negative association. A lower fractal dimension was associated with the presence of diabetes mellitus (p = 0.006), dyslipidaemia (p = 0.011), and a history of acute myocardial infarction (p = 0.018), while a higher fractal dimension was associated with increased left ventricular ejection fraction (LVEF) (p = 0.006) and medical treatment (p = 0.005). Lacunarity was higher in patients of female gender (p = 0.005), with decreased HDL (p = 0.014) and LVEF (0.005), and with increased age (p < 0.001) and Agatston score (p = 0.001). The vessel tortuosity index increased with LV strain (p = 0.05), medical treatment (p = 0.043), and male gender (p = 0.006). Conclusions: Retinal microvascular features may serve as additional risk stratification tools in patients with CVD, particularly CAD, pending prospective validation. Full article

Antibacterial microcapsules were prepared by using a compound of chitosan with an antioxidant of bamboo leaves (AOB) as the wall material and tung oil as the core material. The microcapsules were modified by adding them to waterborne coatings, and the modified waterborne coatings were coated onto Basswood samples. The performance of the obtained coatings was then characterised through a comparative analysis. The investigation focused on the effect of varying percentages of chitosan and AOB in microcapsules with a constant core-to-wall ratio on the performance of the waterborne on the surface of Basswood. The core-to-wall ratio of the microcapsules was established at 1:2, with the ratios of chitosan and AOB in the walls fixed at 9:1, 8:2, and 7:3, respectively. The results demonstrated that the gloss, impact resistance, and hardness of the coatings exhibited an increase with increasing ratios of AOB under varying M_chitosan:M_AOB (M_C:M_A) conditions. Conversely, the adhesion exhibited a decrease with an increase in AOB. The colour difference value exhibited minimal change. The self-healing rate of the coating exhibited an initial increase, followed by a subsequent decrease, in response to the increasing AOB concentration. The antimicrobial effect was optimised at a ratio of 9:1 for the combination of chitosan and AOB. The coating of Basswood containing 1.0% microcapsules and 9:1 M_C:M_A demonstrated superior performance, exhibiting a gloss of 9.7 GU, a colour difference ΔE of 31.03, a hardness of HB, an adhesion rating of grade 1, an impact resistance of grade 4, a self-healing rate of 19.09%, and a noteworthy antimicrobial effect against both Escherichia coli and Staphylococcus aureus. Full article

Background: The main objective of this study was to carry out an online questionnaire in order to assess dentists’ knowledge and perception of dental materials submitted to high temperatures, helping to clarify and raise awareness of possible gaps in the area of forensic dentistry, especially in human identification. Results: Out of a total of 272 respondents, there was a greater influx of responses from countries such as Portugal and Brazil, the majority being female (66.3%), with an average age of 39 years. Most dentists consider complete clinical records to be extremely important. In addition, professionals with less experience provide fewer models in releasing their clinical records. In the case of dental materials, dentists consider composite resin and glass ionomers to be more susceptible to changes in shape and colour, while amalgam is considered the most stable, followed by ceramic and metal-ceramic crowns. On the other hand, dentin is considered more susceptible to colour changes than enamel. Enamel is seen by most professionals as resistant, undergoing few changes in shape at high temperatures. Conclusions: The opinion of the surveyed dentists on this subject is broadly in line with the existing literature. The only observed differences were related to exposure time and enamel resistance, since they assume that enamel is more resistant, and dentin is more vulnerable. Full article

Evaluating the air purification performance of photocatalytic materials typically requires complex gas decomposition tests involving expensive analytical equipment and lengthy testing periods. In this study, photocatalytic performance evaluation methods involving resazurin (Rz) ink and fluorescence probe techniques were investigated as alternatives to conventional gas decomposition tests. TiO₂ films with varying performance levels were fabricated by controlling TiO₂ slurry concentration and the amount of photocatalyst deposited through spin coating. Photocatalytic performances of the synthesised films were then evaluated using the acetaldehyde decomposition method, Rz ink test, and fluorescence probe method for measuring OH radical generation. The acetaldehyde decomposition rate constants showed high correlation with both the Rz colour change rate in modified-pH ink (R² = 0.91) and the OH radical concentration (R² = 0.98). Conventional Rz ink testing for high-performance materials showed rapid colour changes, indicating its limited applicability. Our modified-pH Rz ink enabled facile analysis by ensuring controlled reactivity. Both the modified Rz ink method, which enables quantitative evaluation within five minutes even for high-performance materials, and the fluorescence probe method are suitable as reliable screening tools for photocatalytic air purification materials. These simplified evaluation methods will aid in developing more efficient photocatalysts and advancing environmental purification technologies. Full article

This study investigates the interaction between thermochromic liquid crystal (TLC) inks and bacterial nanocellulose (BNC), emphasizing their compatibility for smart packaging applications. While the chiral nematic structure of TLC pigments dictates their dynamic colour changing behaviour, this research focuses on how TLC inks interact with BNC, a biodegradable and eco-friendly substrate. This study examines material compatibility, colorimetric properties, and the influence of substrate characteristics on the thermally induced colour transitions of TLC inks. Screen printing was employed to deposit TLC inks onto BNC-based films and black uncoated paper, followed by spectrometric analysis to evaluate the temperature-dependent colour response. The results indicate that BNC serves as a promising platform for TLC ink integration, enhancing its potential for intelligent packaging and indicator systems. These findings contribute to the advancement of sustainable, responsive materials for next-generation smart packaging solutions. Full article

Thermosonication is a technique that combines ultrasound with mild temperatures and can be applied as an alternative to thermal pasteurization. This study aimed to evaluate the synergistic effect of thermosonication (Termo) on bioactive compounds (total anthocyanins concentration and total phenolic compounds), antioxidant activity and physicochemical characteristics of blackberry juice in comparison with conventional heat treatment (TT). The experiment was conducted based on the Central Composite Rotational Design, varying the amplitude (60% and 90%), temperature (64 °C and 86 °C) and time (114 s and 517 s) factors. The results showed that the amplitude and temperature factors significantly influenced (p < 0.05) the content of bioactive compounds studied, as well as the antioxidant activity and physicochemical properties, showing that the thermosonication treatment using 60% ultrasonic amplitude and 86 °C temperature provided more excellent retention and less degradation in the content of anthocyanins, phenolic compounds, antioxidant activity, and physicochemical properties (pH, acidity, total soluble solids and colour) of blackberry juice. Higher ultrasonic amplitude (90%) promoted changes in the physicochemical properties and degradation of the bioactive compounds studied and antioxidant activity. However, the limitations of this study are related to the specific matrix used, the seasonality of these fruits, the availability of raw material for processing and the limitation of large-scale ultrasonic equipment. These factors limit the expansion of these findings to other products. Overall, thermosonication can be considered a promising technique. Still, for its implementation as a possible alternative to conventional thermal methods, further studies are needed to investigate the stability of bioactive compounds and antioxidant activity of blackberry juice better. Full article

Wood, a vital material for both modern and heritage objects, is particularly susceptible to degradation caused by water due to its hydrophilic nature and porous structure. Therefore, developing sustainable strategies to protect wood is of significant importance. This study aims to produce a highly hydrophobic coating for the protection of wood following a straightforward procedure and using materials that are compatible with wood. First, nano/sub-microlignin (NL) is isolated and produced from beech wood through a one-step tailored organosolv process. Next, NL is incorporated into Sivo 121, a water-borne and solvent-free silane system recommended by the manufacturer for protecting wood surfaces. Composite coatings containing various concentrations of NL and Sivo 121 are applied to chestnut (Castanea spp.) and oak (Quercus spp.). The impact of NL concentration on the contact angles of water drops (CAs) and colour changes (ΔE) of the treated wood specimens is investigated. The coating with 4% w/w NL demonstrates enhanced hydrophobicity (CA = 145°) and has a negligible effect on the colour of pristine oak (ΔE < 3). The wetting properties of coated oak are not affected after 100 tape peeling cycles. However, the coating exhibits poorer performance on chestnut, i.e., CA = 135°, which declines after 80 peeling cycles, and ΔE > 5. The drop pH does not have any noticeable effect on CA. The latter remains stable even after prolonged exposure of coated oak and chestnut samples to artificial UV radiation and outdoor environmental conditions. Finally, the composite coating offers good and comparable protection for both wood species in the biological durability soil burial test Full article

To investigate the flavour evolution mechanism of raw Pu-erh tea (RPT) during storage, the volatile and non-volatile compounds of RPT with different storage years (1–10 years) from the same raw material origin, manufacturer, and storage location in Wenshan Prefecture, Yunnan Province, were systematically analysed by HPLC, HS-SPME-GC-MS, and OAV. The results showed that both cluster analyses based on non-volatile and volatile compounds could classify RPT of different storage years into three ageing cycles, with key turning points in the third and eighth years of storage, which is also accompanied by the colour changing from green to orange or brown, the aroma changing from a faint scent to woody and ageing, the astringency diminishing, and the sweet and mellow increasing. Theophylline was identified as the potential marker of RPT stored 1–3 years, while (−)-catechin gallate, (−)-gallocatechin gallate, quercetin, and rutin as those for a storage of 9–10 years. The volatile compounds indicate a general trend of an initial increase followed by a decrease. Forty-four key aroma compounds (OAV ≥ 1) were identified. Eucalyptol, β-Caryophyllene, 2-Amylfuran, Copaene, Estragole, and α-Terpinene originated as potential markers for RPT stored 1–3 years, while (Z)-Linalool oxide (furanoid), α-Terpineol, Terpinen-4-ol, and cis-Anethol were for RPT stored 8–10 years. This study revealed the flavour characteristics and quality changes of RPT over the course of storage, and constructed a sensory flavour wheel, providing theoretical underpinnings for the quality control and assessment of RPT. Full article