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Aim: The precise estimation and replication of skin color are crucial for maxillofacial prosthesis. The study aimed to evaluate facial skin color with a colorimeter and suggest a skin shade guide and formula for color estimation. Settings and Design: An observational study conducted in the department of prosthodontics. Materials and Methods: Study was conducted on 368 individuals of Indian origin in age range of 20–45 years. The facial skin color was assessed in malar regions using SkinColorCatch colorimetric device and individual topography angle (ITA) and CIELAB L*a*b* values were noted. Statistical Analysis Used: K-means clustering was utilized to propose a shade guide for maxillofacial prosthesis with 24 skin shades. Logistic regression analysis was conducted to propose a formula to estimate skin shade of the individuals. Results: Based on cluster analysis, 368 subjects were divided into three clusters with similar characteristic as Cluster 1 with dark skin color in 88 (23.91%) subjects, Cluster 2 with medium skin color in 224 (60.87%) subjects, and Cluster 3 with light skin color in 56 (15.22%) subjects. The mean ITA and L*a*b* values for cluster 1 were −47.04° ±14.77°, 34.53 ± 4.31, 8.55 ± 2, 11.42 ± 3.7033, respectively. The mean ITA angle and L*a*b* values for Cluster 2 were 4.29° ±11.34° 51.67 ± 3.42, 8.79 ± 3.13, 21.36 ± 2.38, respectively. The mean ITA and L*a*b* values for Cluster 3 were 34.65 ± 4.29°, 62.66 ± 3.08, 6.53 ± 1.79, 17.73 ± 2.39, respectively. The proposed shade guide comprised a total of 24 different shades that were categorized into three primary colors according to three distinct clusters, each of which was further broken down into eight subclusters containing various shades within each cluster. Logistic regression analysis gave an equation as follows: Y =12.43 + 0.186X (Y = Predicted skin color, X = ITA angle). Conclusions: Twenty-four facial skin shade tabs have been proposed based on ITA angle and CIELAB values. This comprehensive approach to categorize the shades will ensure a detailed and organized system for selecting and matching colors in maxillofacial prosthesis.

Abstract Background This study proposes a simple digital image colorimetric method using a smartphone for the quantitative analysis of isoniazid in pharmaceutical medications. The analytical methodology employed in this study involved the utilization of the reaction between isoniazid and FC reagent under alkaline conditions. The chemical reaction led to the creation of a complex with a blue-gray color, exhibiting a peak absorption at a wavelength of 760 nm. An Android application was employed to perform a smartphone-based determination based on separating the captured color into different color channels such as red, blue, green, etc. The experimental procedure involved the utilization of three smartphones for the determination, which was subsequently followed by a comparative analysis of the results obtained from these devices using spectrophotometric measurements. Results The B channel had the highest level of optimization in terms of analytical parameters. The limits of detection (LOD) were 0.586, 2.478, and 1.396 µg/ml for S1, S2, and S3, respectively, and for the spectrophotometer, it was found to be 0.416 µg/ml. Similarly, LOQs were determined as 1.673, 7.511, 4.232, and 1.302 µg/ml. A %RSD of 1.3 for precision and an LOD of 0.013 g dm−3 were obtained for the spectroscopic method. The % recovery in the accuracy study was found to be 99.69, 101.804, 109.28, and 100.13 for S1, S2, S3, and spectrophotometer, respectively. Conclusion The colorimetric results from smartphone application are similar to those from spectrophotometric analyses.

Abstract The color of pyroclasts is fundamental, because it reflects various magma properties and eruption processes, including particle morphology, chemistry, and petrological characteristics. However, deriving the componentry ratio (CR) of pyroclasts for ongoing eruption monitoring remains challenging due to the lack of a robust quantitative standard. The derivation of the CR, as well as other petrological analyses, is too laborious and time-consuming to introduce as a sustainable monitoring method. To address this, we employed spectroscopic colorimetry to rapidly and quantitatively describe eruptive product colors, enabling CR derivation based on clear, objective standards for ash particle classification. Through color spectroscopy of bulk and sieved ash samples, we analyzed the major size fraction for time-series samples during the waxing stage of the 2017–2018 Shinmoe-dake eruption in Kirishima volcano, Southwest Japan. Our findings reveal that the color changes in bulk ash systematically changed with the evolution of componentry. This temporal color change was due to an increase in the amount of vesicular particles with clear glass against dark angular lava particles, as well as a grain size change, which we interpret as an indication of a transition from phreatic/phreatomagmatic to magmatic eruption. Subsequently, the color of the ash changed when the amount of different lava particles increased gradually, coinciding with a shift toward a more dominant effusion of lava. As the lava effusion continued, a slight reddening of the ash, indiscernible to the naked eye, was clearly detected by the spectrometer before the onset of intermittent Vulcanian eruptions. We interpreted this reddening as oxidation resulting from decreased ascent speed and caprock formation, which accumulates overpressure for Vulcanian explosions. These results highlight the potential of rapid, objective color value and componentry derivation for sustainable quasi-real-time monitoring of ongoing eruption materials. Graphical Abstract

Abstract A fast eco-friendly colorimetric method was developed for the determination of Tobramycin in drug substance, ophthalmic formulations, and spiked human plasma using silver nanoparticles optical sensor. Even though tobramycin is non-UV–visible absorbing, the developed method is based on measuring the absorbance quenching of silver nanoparticles resulting from the interaction with tobramycin. Different factors affecting the absorbance intensity were studied as; silver nanoparticle concentration, pH, buffer type, and reaction time using quality by design approach. Validation of the proposed method was performed according to ICH guidelines and was found to be accurate, precise, and sensitive. The linearity range of tobramycin was 0.35–4.0 μg/mL. The optical sensor was successfully applied for the determination of Tobramycin in ophthalmic formulations and spiked human plasma without pre-treatment. Additionally, the binding between Tobramycin and PVP- capped silver nanoparticles was studied using molecular docking software. The method was assessed and compared to colorimetric reported methods for the green character using Green Analytical Procedure Index (GAPI) and Analytical GREEnness calculator (AGREE) tools and found to be greener.

The study concerns the behavior of optical and colorimetric properties of cadmium telluride semiconductor colloidal quantum dots covered with silica shell (CdTe/SiO2, core/shell) in an external constant electric field has been studied. To date, the electric field is known to lead mainly to quenching and red shift of the luminescence spectra of quantum dots; however, in most of the corresponding studies only the behavior of band-edge luminescence is considered. In this work, in addition to the luminescence due to interband transitions, the effect of the electric field on the trap-related luminescences of core/shell quantum dots is studied. Semiconductor nanocrystals were synthesized by colloidal chemistry methods. The product mixture was a solution of quantum dots in an aqueous medium. To investigate the optical properties of CdTe/SiO2 nanoparticles in an external electric field, a series of samples was fabricated on the basis of an optically passive cellulose film, in the pores of which quantum dots were embedded. The final sample was a cellulose film with quantum dots sandwiched between two glasses with transparent indium tin oxide electrodes. The strength of the constant electric field applied to such structures reached 140 kV/cm. Photoluminescence spectra of the investigated nanostructures were recorded using a CCD spectrometer. As a result of the experiments it was found that the presence and subsequent increase of the external electric field leads to quenching of the intensity of both band-edge and traprelated photoluminescence of quantum dots. This fact is associated with a decrease in the overlap between electron and hole wave functions under the action of the electric field. It is also shown that at moderate field strength there is a slight increase in the total photoluminescence intensity. This observation can be related to impeded charge carrier trapping. The demonstrated quenching of luminescence intensity is also consistent with the results of other authors who have shown a decrease in the absorption of quantum dots in external electric fields. The stability of colorimetric characteristics of the spherical nanoparticles in an external electric field has been demonstrated. The results of the study can be used for development of optoelectronic devices based on CdTe/SiO2 nanoparticles.

Aim: The aim of this study is to Quantify sialic acid for oral cancer diagnosis using different method using densitometric analysis. Background: Early detection of OSCC is critical for improving survival rates and reducing morbidity, which has prompted researchers to look for potential biomarkers to aid in early diagnosis. Saliva is an excellent diagnostic tool due to its noninvasive nature. Sialic acid levels in saliva have been found to be higher in cancer patients. Hypersialylation is associated with poor prognosis and accelerated cancer progression, as well as immune escape, tumor growth and spread, angiogenesis, and resistance to apoptosis and treatment. This study addresses the imperative need for adaptive, effective, and non-invasive strategies in the diagnosis and treatment of oral cancer, emphasising the importance of early detection for improved prognosis. This study introduces various methods for quantify levels of sialic acid in saliva, including resorcinol and orcinol assays, using colorimetric and densitometric assays. Material and Method: In this study, sialic acid detection methods have been standardized using standards as well as spent media from cancer cell lines to develop noninvasive diagnostic tools for early detection. Two methods used for the detection of sialic acid Resorcinal and Orcinol method by densitometric analysis using Image J software. Results: The study has successfully quantified sialic acid from spent media and saliva using resorcinol and orcinol method by densitometric analysis. Conclusion: In this study we aim to develop a reliable and cost-effective method for quantification of sialic acid using Image j software. The approach presents a non-invasive and efficient alternative for early cancer diagnosis showcasing its potential impact on advancing diagnostic technologies.

Abstract Pentachlorophenol (PCP) is a manmade chemical that is widely present in the environment and is mostly used as a wood preservative. Therefore, to conduct remediation studies, it is imperative to determine the most effective PCP analytical technique. PCP can be analyzed using a variety of analytical tools, including non-destructible methods like X-ray fluorescence spectrometry (XRF) and electrochemical sensors (EC), destructible tools like gas chromatography (GC), thin layer chromatography (TLC), colorimetry, ultraviolet–visible and infrared spectroscopy (UV–vis/IR), and high-performance liquid chromatography (HPLC). the colorimetric approach is less recommended because of its low sensitivity and precision, whereas TLC offers superior recovery rates and precision but is expensive, takes longer, and is unable to resolve complicated combinations. Higher recovery rates, sensitivity, precision, and superior separation are all offered by HPLC; however, its effectiveness is impacted by time, money, and solvent compatibility. The most favored destructible approach is GC because it is efficient in terms of both cost and time and offers superior precision and separation. Although XRF is frequently used in the wood industry to test PCP in treated wood and treating solutions, scientific research has avoided using it because of its high cost and ability to identify chemicals based only on their elemental composition—in the case of PCP, it is chloride. Among all methods, EC is shown to be more dependable than the other methods listed because it is extremely specialized, less expensive, and offers a faster response. It is possible to make more changes to the current analytical techniques, such as enhancing extraction techniques, creating a universal HPLC column, developing more affordable and high-precision EC electrodes, and evaluating a larger variety of samples from different matrices. This review has shed light on the many analytical tools available for determining PCP and the knowledge gaps in the field of study.

Bioactive compounds have been shown to promote healthy human development and protect against certain diseases including some cancers. Tropical pumpkins bred for consumption, such as calabaza (Cucurbita moschata), possess these compounds, though concentrations vary considerably between varieties. Bioactive compound quantification methods can be expensive, complex, and generate considerable hazardous waste. A predictive tool utilizing the relationship between extrinsic properties and tristimulus colorimetry values of calabaza would allow for significantly higher throughput with lower requirements for equipment, training, and laboratory consumables. Therefore, this study examined correlations between flesh color and bioactive compound quantities of several calabaza germplasm lines to assess the utility of a sustainable and portable predictive tool. CIEL* a* b* values of pumpkin flesh were assessed using a colorimeter and compared to bioactive compound concentrations determined analytically. Redness was found to correlate with increased ascorbic acid and total soluble solids content. Yellowness correlated with β-carotene equivalent carotenoids and ascorbic acid content. These results suggest that colorimetry may be a viable pre-screening technique for quantifying bioactive compounds in C. moschata.

The bovine lungworm, Dictyocaulus viviparus (Bloch, 1782), is highly pathogenic and disease outbreaks can be difficult to predict and manage. Rapid and accurate diagnosis is vital, but without a sensitive diagnostic test this remains challenging in clinical practice. High performance molecular detection tools are therefore required to improve the diagnosis of this parasite and promote the implementation of strategic control measures. Loop-mediated isothermal amplification (LAMP), a rapid DNA assay, offers potential for field-based detection. Here we report a novel LAMP assay (DviLAMP), that was designed to target the D. viviparus internal transcribed spacer 2 (ITS2) ribosomal DNA region. Firstly, genomic DNA was extracted from a single D. viviparus L1 larva to amplify and clone the ITS2 into the recombinant plasmid (DviITS2). The DviLAMP successfully detected the target, with results shown by gel electrophoresis and real-time analysis, in addition to point-of-care amenable end-point detection: colorimetry and lateral flow dipstick (LFD). Analytical sensitivity can detect 0.5 ng DviITS2 following 45 min of incubation at 64°C, increasing to just 1 pg following 90 min of incubation. Using the same primers, other nematodes of cattle, Ostertagia ostertagi and Cooperia oncophora, were also detectable both by gel electrophoresis and real-time. However, when FITC and biotin tagged primers were incorporated to adapt the DviLAMP to LFD end-point detection, the LFD showed specific detection of D. viviparus. Further development of DviLAMP as a point-of-care test could significantly improve the sensitivity of lungworm diagnosis in the field.

. This study aimed to develop a paper-based glucose sensor using artificial sweat and saliva samples, a non-invasive, practical, and affordable concept for measuring glucose levels. The chosen method was the colorimetric method using the Glucose Oxidase (GOx) enzyme, Horseradish Peroxidase (HRP) enzyme, and 3,3?-diaminobenzidine (DAB) chromogen. The wax stamping method was utilized on a piece of filter paper to test the glucose sensor. The test was carried out in several stages, including testing various concentrations of reagents and wax stamping sizes, fabricating the glucose sensors, and testing multiple concentrations of glucose, artificial sweat, and artificial saliva. The RGB method was used to test the resulting color. The data obtained were then validated using UV-Vis Spectrophotometry. The GOx concentration on the glucose sensor affected the color change velocity. The HRP, DAB, and wax stamping size concentration simultaneously indicated a strong correlation with changes in the color intensity that appeared on the glucose sensor. The glucose sensor in this study could measure the glucose concentration of the artificial sweat and saliva samples, respectively, from 0-3000 and 0.9987. This study proved a strong correlation between the reagents' concentration and the color intensity on the developed glucose sensor.

Background: Plant solutions or decoctions are fermented with added sugar to create alcoholic remedies like arishta and aasava. Standardizing ayurvedic formulations is essential to assessing the quality of medicine. Objective: Standardisation of Lohasava, which contains iron as a metal and is used as hematinic, has been carried out in the current study. Methods: The standard ayurvedic procedure was used to prepare the aasava formulation. Modern scientific control processes have standardized the formulation for the final products. Organoleptic analysis, phytochemical assessment, and physicochemical characteristics such as pH, specific gravity, viscosity, acid values, total solid content, alcohol content, heavy metal content, and stability studies were used to standardize asava. Additionally, formulations were examined for the presence of pesticides. Using UV-visible spectrophotometric analysis, the iron content was determined. Animal studies were carried out to evaluate pharmacological activity. Results: Physical and chemical parameters were found within limits. The alcohol content of formulations was within limits and indicated good fermentation. Conclusion: The study's findings have revealed good formulation quality and provide a standard for aasava and ayurvedic formulations.

Objective: In this study, a colorimetric sensing system based on different aptamers and AuNPs was constructed for the rapid quantitative detection of aflatoxin M1 (AFM1) in milk. The detection performance of AFM1 aptamers with 21 (A21) and 72 base (A72) lengths commonly used in literature reports was evaluated in actual samples. Methods: AuNPs solution was prepared by sodium citrate reduction. After adding AFM1 aptamer and AFM1 standard solution, the aptamer specifically combined with AFM1 to form a special three-dimensional structure. With the addition of NaCl solution, the stability of AuNPs solution was disrupted and aggregation occurred, resulting in color change of the solution. AFM1 was quantitatively detected by measuring the absorbance value and absorption spectrum of AuNPs solution. Results: Under the optimum condition, the limits of detection of AuNPs-aptasensor based on A21 and A72 aptamers were 25.26 µg/L and 5.77 µg/L, respectively, with the linear range of 10~800 µg/L. Moreover, the AuNPs-aptasensor had good selectivity and specificity. The recoveries of AuNPs-aptasensor based on A21 and A72 aptamers were 95.7%~103.6% and 94.3%~98.2%, respectively. Conclusion: The A72 performed better than A21 in detecting AFM1 in milk, which would be related to the length, configuration and affinity of the aptamer. The colorimetric sensing method established based on aptamers A72 was simple, fast, sensitive, highly specific, and visualized, providing data reference for the application of AFM1 aptamers in dairy products.

Urea levels in urine play an important parameter in diagnosing bodily conditions through liver and kidney examinations. The typical reagent for detecting urea content in urine is para-dimethylaminobenzaldehyde (pDMAB). However, it has a drawback related to the instability of color in the resulting Schiff base compound (pDMAB-urea). In this study, the synthesized vanillin compound derived from clove oil serves as the foundational material for a urea chemosensor based on the colorimetric concept. The synthesized vanillin was characterized using FTIR, GC-MS, and 1H-NMR. The formulation of the vanillin compound as a sensor was conducted by assessing the suitable solvent, determining the optimal mass of vanillin, and evaluating the acid-base conditions of the sensor formulation system both qualitatively and quantitatively. Subsequently, the most effective formulation was selected for detecting urea in urine samples. The synthesis of vanillin yielded a purity level of 95%. The optimal formulation was obtained at an optimum mass of vanilla of 0.75 g in 50 mL of 96% ethanol and 10 mL of 10% NaOH. The color change in the sample was from colorless to greenish yellow (436 nm). The vanillin obtained was applied to urine samples with the best results at a sample dilution level of 10,000×.

Potsherds from Phra Mahathat Woramahawihan, a revered Buddhist temple in Thailand’s Nakhon Si Thammarat Province, were studied in the context of maritime Southeast Asia and local craftsmanship during the thirteenth–fourteenth century. The CIE L*a*b* and CIE L*C*h* colors of fine- and coarse-paste wares were analyzed using unsupervised and supervised machine learning algorithms. An illustrative example demonstrated the classification capability and cluster prediction. The example showed that supervised machine learning algorithms effectively discriminated between classes with similar characteristics, making colorimetry classification feasible. The kNN classifier achieved an overall accuracy of 87.10%, with high precision measurements (0.90). The supervised approach outperformed in color recognition and classification accuracy for the L*C*h* and combination of L*a*b* and L*C*h*. This strong inter-site discrimination capability is valuable in pottery research. The significantly lower color values of potsherds from Phra Mahathat Woramahawihan temple suggest multiple earthenware production sites in peninsular Thailand during the thirteenth–fourteenth century.

We constructed a liquid-phase colorimetric biosensor to detect Triglycerides (TG) contamination in water using a Porcine Pancreatic Lipase Immobilized Zinc – chitosan nanocomposite matrix with Phenolsulfonphthalein as the chromophore. The nanoparticle-augmented matrix was characterized using an SEM—the change in the chromophore colour from red to yellow indicated vegetable oil hydrolysis and fatty acid release. The biosensor showed a LOQ between 25–500 µg/mL at an operating temperature between 25–45 °C, over a pH range of 4–9 within 5 minutes. The biosensor showed resilience to samples contaminated up to 50 times the BIS permissible limits for iron, copper and manganese. The sensor showed repeatability of nearly 100% with the LOD 3 µg/mL, sensitivity 47.1 U/µg/cm2 and retained up to 80% of its activity till the 10th day when stored at 10 °C. A fully adept version of the biosensor can be applied to detect TG in water and wastewater.

A novel selective membrane optode was prepared to determine of ultra-trace amounts of lead. This state-of-the-art optode amalgamates a bespoke ionophore, 4-(thiazol-2-yldiazenyl)benzene-1,3-diol (TDBD), with ETH-5294, assuming the role of a chromoionophore. This potent composition converges with sodium tetraphenylborate (NaTPB) and dioctyl phthalate (DOP), harmoniously enclosed within a matrix of poly(vinyl chloride) (PVC). The influence of various parameters on the preparation of the optode and the determination of Pb2+ was investigated and optimized. Evidently, the optode unfurls an expansive linear dynamic expanse, spanning an astonishing range from 6.0 × 10−9 to 8 × 10−5 M. Remarkably, it retains an astonishingly low degree of detection and quantification, registering at 1.75 and 5.85 × 10−9 M, respectively. The response time of the optode was 4.0 min. The optodes versatility extends its embrace towards rejuvenation, permitting multiple rounds of service via 0.2 M HNO3 solutions. The effect of potential interference ions on the Pb2+ determination was illustrated. The results showed that the prepared optode was very selective to lead ions so that it had no significant response to common ions such as Mg2+, Mn2+, Cd2+, Ni2+, Fe2+, Fe3+, Hg2+, Cu2+, and Co2+. The optode was applied successfully to determine of Pb2+ indifferent food, biological and environmental samples and result obtained is comparable to atomic absorption spectrometry method.

A novel optical probe has been successfully developed for the selective detection of Os(VIII) ions. This osmium-sensing platform was intricately designed by incorporating 4-(thiazol-2-yldiazenyl)benzene-1,3-diol (TDBD) as the ionophore within a plasticized PVC membrane, and tributylphosphate (TBP) serving as the plasticizer. Upon exposure to Os(VIII) ions in a 0.5 M HClO4 acid milieu, the sensing membrane undergoes a distinctive chromatic transition, shifting from a yellow to a pink hue. The preparation of the sensor and the methodology for Os(VIII) determination were meticulously refined to achieve optimal performance. Under these carefully optimized experimental conditions, the proposed optode demonstrated an impressive linear detection range spanning from 2.5 × 10−9 to 2.5 × 10−5 M for Os(VIII), alongside remarkable detection and quantification limits of 7.24 × 10−10 and 2.4 × 10−9 M, respectively. The sensor consistently delivered highly reproducible results, as evidenced by relative standard deviation (RSD) values of 1.45% and 1.30% for Os(VIII) concentrations at 7.5 × 10−7 and 2.5 × 10−6 M, respectively, underscoring its precision and reliability. Furthermore, the sensor exhibited a swift response time of 3.0 min, further emphasizing its efficiency. The incorporation of PIMs into the sensor architecture led to a remarkable eight-fold enhancement in its response compared to counterparts lacking PIMs, signifying a significant performance improvement. In assessing potential interference, an investigation into the influence of other ions on Os(III) determination revealed that the prepared sensor displayed exceptional selectivity for Os(VIII) ions, with negligible responses observed in the presence of common ions. Collectively, these experimental findings underscore the sensor's efficacy as an invaluable tool for the precise analysis of osmium content in water samples, aligning it with the rigorous standards of international scientific research.

ABSTRACT This study aimed to evaluate the duplicity and synergism of slow drying and storage processes at low temperatures, using a refrigerated room under suitable conditions for coffee fruit just after harvest. A cold room was prepared to receive and store coffee fruit in bulk directly from the field, perform slow drying, and maintain water content at approximately 12% during three months of storage. The room operated at temperatures between 7 and 14 ºC and relative humidity between 37 and 41%. The coffee variety used was the Conilon Yellow 62. The initial water content reduction period from 54% (wb) to 12% (wb) was two months. For comparison, coffee harvested from the same batch was dried on a covered suspended bed. Results showed that the coffee dried and stored in the cold room received a sensory score of 86.41, while that dried on a suspended bed obtained a sensory score of 84.16. Moreover, the coffee dried and stored in the cold room had a higher energy content. Colorimetric analysis showed that the dried grains stored in the cold room had a reduction in the "a" coordinate, indicating an approximation to the green color. The cold room also allowed for extended storage of the coffee grains.

A colorimetric assay was developed for detection of indole-3-carbaldehyde (I3A), a bioactive compound particularly abundant in vegetables of the Brassicaceae family, inducing plant defense responses and ensuring the human intestinal barrier integrity. The assay is based on the selective condensation reaction between the hydrazine group of carbidopa, used as a derivatizing agent, and the aldehyde group of I3A, generating a colored aldazine with a characteristic absorbance around 415 nm. As proof of concept, among the several natural sources here reported in a quantitative data collection, the colorimetric assay was assessed in white heart cabbage ethanolic extract. I3A content was determined by LC-MS analysis, which confirmed the colored aldazine formation in matrix. The LOD (10.4 ± 0.3 μM) obtained by the calibration curve from the visible absorbance (m = 565 ± 16 M−1, avRSD % 6.5, R2 = 0.9960) indicates that this simple, safe, and low-cost method could be beneficial also for current methodologies for identification and quantification of I3A in foods.

This study aimed to synthesize magnesium oxide (MgO) using a colloidal starch method for two primary purposes: the removal of chromium (III) ions from synthetic wastewater and the subsequent use of the chromium-containing material as synthetic inorganic pigments (SIPs) in commercial paints. The synthesis used to obtain the oxide (St-MgO) is a promising method for using plants, such as cassava, as green fuels due to their abundance, low cost, and non-toxicity. With this, the oxide showed greater porosity and alkalinity, compared to commercial magnesium oxide (Cm-MgO). The MgO samples were subjected to structural characterization using XRD and FTIR, surface area and pore volume study by B.E.T. and SEM, and chemical composition by ICP-OES and thermogravimetric analysis (TGA). The crystalline periclase phase was identified for both samples, but the brucite phase was shown to be a secondary phase for the commercial sample. After the removal of chromium ions, the brucite crystalline phase became the majority phase for the samples, regardless of the concentration of ions removed. The pigments were characterized by color measurements and discussed in terms of colorimetric parameters using the CIELab method and electron spectroscopy (VIS-NIR). This study also evaluated the colorimetric stability of green pigments in aggressive environments (acidic and alkaline) over a 240 h exposure period, demonstrating minimal color difference. This study aims to develop materials for the decontamination of wastewater containing chromium and its reuse as a synthetic inorganic pigment, using an innovative and sustainable synthesis method.

One of the precious metals that has numerous applications is gold. Although it is non-toxic and biocompatible, the oxidized form, Au3+, is toxic and can cause damage to human organs. Detection of Au3+ becomes a necessary and interesting topic to be conducted. Colorimetric analysis using metal nanoparticles such as silver nanoparticles (AgNPs) can analyze metal ions more simply, sensitively, and selectively than traditional methods. In this research, AgNPs were synthesized using polyvinyl alcohol (PVA) and ascorbic acid as stabilizers and reducing agents. The interaction between Au3+ and AgNPs selectively decreased the absorbance intensity of AgNPs and altered the color of colloidal AgNPs from yellow to colorless. These two phenomena indicated a redox reaction between Au3+ and AgNPs, leading to the decomposition of AgNPs. The decomposition of AgNPs (the proposed mechanism) was confirmed by TEM images and UV-vis spectra. The decrease in AgNPs’ absorbance intensity correlated linearly with the increase in added Au3+ concentration. The calibration curve of ∆A versus Au3+ ion concentration yielded LOD and LOQ of 0.404 and 1.347 μg/mL, respectively.

This research investigates the light quality and thermal management of InGaN and InGaAlP Light Emitting Diodes (LEDs) under various light regulation methods. We compare Continuous Wave (CW) and Pulse-Width Modulation (PWM) modes, examining their impacts on luminous flux, temperature, total color shift, and angular color shift. Our findings reveal that the CW mode offers higher luminous flux and reduced temperatures, while the PWM mode ensures enhanced color stability across different currents and viewing angles, especially for white LEDs; however, this stability does not extend to other LED types. From both optical and visual performance perspectives, the study emphasizes optimizing the driving current to meet regulatory requirements and ensure consistent color perception. These insights are crucial for automotive lighting design, contributing to improved regulatory compliance and aesthetic quality.

The color of a product is one of the main factors that affect consumer choices. However, it can be difficult to discern the subtle differences in color in order to inspect or classify products without expensive and specialized equipment. In this study, we proposed an approach where standard off-the-shelf components (digital camera and RGB LED lights) can be used to robustly classify products based on their color. By varying the color of the illumination, environment-independent information of the color of the object can be obtained. Then, using a Log-Linearized Gaussian Mixture Neural Network (LLGMN), a neural network based on a statistical model, the objects can be effectively and robustly classified based on their color without requiring a large number of training data. An experiment was performed to verify the effectiveness of this approach. 8 samples with only a subtle difference in color were prepared, and a prototype was developed to be used to classify these 8 samples. We demonstrate that we are able to classify the 8 samples an accuracy of 100% when there was no ambient light and were still able to maintain an accuracy of 94.1% when there was ambient light in the room.

Background: The purpose of this study is to investigate the tooth whitening effect of Listerine Healthy White and provide effective management of extrinsic discoloration by comparing the whitening effects of existing whitening products.Methods: The included study four groups: those using whitening gel, whitening toothpaste, and Listerine Healthy White and a control using artificial saliva. Each group received 40 bovine tooth specimens, which were stained with commonly consumed tooth-coloring-inducing foods; black tea, black coffee, and instant noodles for 72 hours. The specimens were treated with tooth whitening materials for 5 weeks, after which the lightness (L*) was measured weekly using a spectrophotometer. Results: There was a significant difference in lightness among the groups between the 1st and 5th week of treatment for all tooth-coloring-inducing foods (p＜0.05). When comparing the changes in lightness values from before whitening to the 5th week of whitening for all tooth-coloring-inducing foods, the order of change was as follows: whitening gel, whitening toothpaste, Listerine Healthy White, and artificial saliva. Listerine Healthy White showed a significant whitening effect for all tooth- coloring-inducing foods (p＜0.05). Particularly, changes in lightness values for specimens stained by black tea after 5 weeks of whitening were in the following order: whitening gel (21.72), whitening toothpaste (14.89), Listerine Healthy White (12.91), and artificial saliva (3.85). For specimens stained by black coffee, the changes in lightness values were in the following order: whitening gel (12.99), whitening toothpaste (9.66), Listerine Healthy White (7.91), and artificial saliva (3.12). Lastly, changes in lightness values for specimens stained by instant noodles were as follows: whitening gel (10.84), whitening toothpaste (9.85), Listerine Healthy White (7.71), and artificial saliva (2.61). Conclusion: Listerine Healthy White exhibits continuous whitening effects over time, and for consumers seeking convenient ways to achieve tooth whitening effects at home, consistent use of Listerine Healthy White is recommended.

Introduction Manufacturers are trying to replace plastic materials in the food packaging industry with biodegradable and edible films. Biodegradable edible films and coatings are mainly made from carbohydrates, lipids and proteins and their mixtures. In recent decades, various carbohydrates from plant sources have been investigated and introduced as new compounds for the preparation of these films. Flaxseed gum is a white to cream-colored powder that dissolves in water and produces a gel, and is a desirable compound for forming films and coatings. Recently, through the integration of reinforcements or fillers with at least one nanometer dimension in the substrate of one or more natural biopolymers, the physicochemical, mechanical, optical, thermal and barrier properties of pure biofilms have been improved. The use of cellulose nanoparticles in biofilms as a reinforcing agent for polymer materials leads to the creation of composite films with better quality characteristics and leads to the creation of functionalization activities in film production. Therefore, the aim of this research was to produce and characterize edible and biodegradable film based on the combination of flaxseed gum and cellulose nanocrystals. Materials and Methods Cellulose nanocrystals (Degree of crystallinity: 42% and average particle size: 58 nm) were extracted from cotton linters. Glycerol and other chemicals used for this research were obtained from Merck, Germany. Flaxseeds were purchased from the local market of Shiraz (Iran). Bionanocomposite films were prepared from different ratios (0:100, 30:70, 50:50, 70:30 and 100:0) of flaxseed mucilage (2% w/v) and cellulose nanocrystal (6% w/v) solutions. The prepared solutions were poured on a petri dish with a diameter of 15 cm and dried in an oven at 80°C for 4 hours. Their physical, color and mechanical properties were investigated and the best ratio was selected for the preparation of bionanocomposite film. The produced films were subjected to different analysis to determine thickness, solubility, water absorption capacity, permeability to water vapor, tensile strength, elongation at break point, and colorimetry. The microstructure of the produced film was studied using a scanning electron microscopy (SEM).The average data were analyzed by analysis of variance in a completely randomized design using SPSS 22.0 software. Differences between treatments were expressed in Duncan's multiple range test at the 95% probability level (p

Road markings (RMs) typically consist of a paint layer and a retroreflective layer. They play a crucial role in road safety by offering visibility and guidance to drivers. Over their lifetime, dirt particles, oils, and greases are adsorbed on the RM surface, reducing their visibility and service life. A self-cleaning ability has been widely studied in several substrates. However, for RMs, this represents a breakthrough and a sustainable advance, while having the potential to increase their service life and enhance road safety. In this context, nanotechnology can be a strong ally through the application of semiconductor materials, such as TiO2, to develop the self-cleaning ability. In addition to this novelty in RMs, quantifying this ability in terms of pollutant removal efficiency is also a challenge. In this sense, artificial intelligence (AI) and colorimetry can be combined to achieve improved results. The aims of the work herein reported were to assess the self-cleaning capability in an RM paint through the mass incorporation of semiconductors, evaluate their photocatalytic efficiency using traditional (spectrophotometric) and modern (AI-enhanced) colorimetry techniques, and compare the results obtained using both techniques. To this end, a water-based acrylic RM paint was modified through the mass incorporation of 0.5%, 1%, 2%, and 3% of nano-TiO2, and a pollutant model widely used, Rhodamine B, was applied onto their surface. The samples were irradiated with a light source that simulates sunlight for 0, 3, 6, 12, 24, and 48 h. Visual analysis and spectrophotometric and artificial intelligence-enhanced colorimetry techniques were used and compared to evaluate the pollutant removal. The results confirm that RM paints with 2% and 3% nano-TiO2 incorporated have a significantly higher pollutant removal ability and that both colorimetric techniques used are suitable for this assessment.

Immunoassays have been widely used for the determination of various analytes in the fields of disease diagnosis, food safety, and environmental monitoring. Dual-signal immunoassays are now advanced and integrated detection technologies with excellent self-correction and self-validation capabilities. In this work, we summarize the recent advances in the development of optical and electrochemical dual-signal immunoassays, including colorimetric, fluorescence, surface-enhanced Raman spectroscopy (SERS), electrochemical, electrochemiluminescence, and photoelectrochemical methods. This review particularly emphasizes the working principle of diverse dual-signal immunoassays and the utilization of dual-functional molecules and nanomaterials. It also outlines the challenges and prospects of future research on dual-signal immunoassays.

The appropriate preservation and color rendering of paintings and art pieces are a pending subject in architectural heritage, since, in most of the cases, lighting systems are not really focused on the conservation and suitable perception of these heritage resources, due to the limitations of standard LED lamps and lighting configurations. In this context, a multichannel luminaire system is proposed in the case study of the Cathedral of Seville, providing a variable and rich spectral distribution, which allows an excellent color perception linked to the daylight conditions, while the short-wavelength light is minimized in order to reduce photodegradation. Two scenarios are addressed: Museum of the Cathedral and Evangelist Chapel. The multichannel luminaire system is tested by means of subjective surveys and objective procedures (Farnswoth-Munsell and Natural Color System tests). The results show that the proposed spectral distribution of the multichannel system provides a better color discrimination in comparison with typical lighting systems, as well as a better preservation, defining a suitable lighting technology for architectural heritage. The novelty of this study lies in the multi-parameter approach, taking care of color rendering while photodegradation is minimized.

The advent of portable Fourier-Transform Infrared (FTIR) and Raman spectrometers has revolutionized analysis capabilities, presenting the possibility of on-site contaminant identification without the need for specialized laboratory settings. Compared to laboratory instrumentation, portable spectroscopy is more prone to noise, and appropriate spectral processing procedures need to be established. This paper introduces a comprehensive methodology that integrates acquisition techniques, spectral analysis, and mathematical tools necessary for utilizing handheld spectrometers to diagnose plant contamination. It focuses on determining the efficacy of handheld FTIR, Raman spectroscopy, and digital imaging for detecting contaminants in two food plants, Basil (Ocimum basilicum) and Mint (Mentha). The study examines the impact of three pollutants: iron (II) sulphate (FeSO4), zinc (II) sulphate (ZnSO4), and copper (II) sulphate (CuSO4), on these plants, but also the necessary amount of measurements to spot the pollutants' effects. Measurements were conducted at the start, after 24 hours, and after 48 hours of exposure, on both fresh and dried plant leaves, as well as in solution. Spectral effects of each of the pollutants were identified with the use of multivariate statistical process control techniques. With the help of the developed methodologies, researchers can identify in-situ contaminant effects, exposure times and run diagnostics directly on the leaf both in alive and dried plants.

The selective detection of halides in aqueous samples is crucial for addressing environmental and physiological concerns. Consequently, the development of an affordable, portable, and user-friendly sensing platform for rapid halide detection holds substantial promise. In this study, we present a novel paper-based nanosensor as an appealing alternative for selectively detecting halides in water. This nanosensor leverages the optical properties of silver nanoparticles (ranging from 50 to 250 nm) embedded in epoxy resin and printed on filter paper. We elucidate the colorimetric behavior of this nanosensor in response to specific halides (chloride, bromide, and iodide) upon contact. Importantly, this sensor discerns, through a single measurement, the presence of these halides in aqueous media with remarkable selectivity. The nanosensor manifests distinct color changes in reaction to different halides, particularly at elevated concentrations (ranging from 2 to 400 mM), surpassing the saturation levels observed in other proposed sensors. These discernible color changes are due to the oxidation of silver nanoparticles, changing their morphology and aggregation density, and can be readily detected and analyzed directly from a captured image. Consequently, it demonstrates considerable potential for integration into automated qualitative monitoring devices based on chromaticity analysis.

Abstract Brazil has emerged as the world's largest producer of annatto seeds (Bixa orellana L.). Fortunately, the increase in national production has been accompanied by an improvement in the quality of this raw material. Annatto is a typical crop of small producers who usually use their empirical knowledge to evaluate the quality of the crop. Thefore, the visual observation of the color of annatto seeds has been considered a quality standard by many producers. To evaluate the scientific evidence, the present study evaluated annatto seeds from 51 accessions of the germplasm bank of the Agronomic Institute (Instituto Agronômico de Campinas - IAC) to determine a possible correlation between the pigment’s contents and the color of annatto seeds as well as the influence of humidity on this correlation. The correlations between the concentrations of pigments, humidity, lipids, and color (L*, a*, b*) were also evaluated. The color was evaluated using a colorimeter with measurements of the CIE L*, a*, b* scale. Only the correlation between the variables moisture and lipids was considered strong through the simple correlation, while the variables bixin content and coordinate a* presented a significant correlation while eliminating the effect of moisture (partial correlation). Thus, a correlation between the red color and the bixin concentration of annatto seeds was observed even though it was a weak correlation. In turn, the color difference (ΔEab) between the samples with higher and lower bixin contents was only 1.44. This difference indicates that large variations in the bixin concentrations may lead to small color changes in the annatto seeds, impairing the use of this criterion for quality control of these seeds.

Insoluble contaminants and varnish, resulting from oil degradation byproducts and sometimes depleted additive molecules, are initiated primarily due to thermal stress on the oil. This poses significant challenges in tribology, particularly for the lubrication systems of modern complex machinery, leading to severe debilitating effects such as loss of operating clearances and impaired heat transfer. Addressing varnish buildup is crucial, and timely oil analysis emerges as a valuable tool, offering essential insights into the oil degradation level and the potential presence of insoluble contaminants. Among the various laboratory testing methods available to assess varnish potential, colorimetric analysis, specifically Membrane Patch Colorimetry (MPC), is widely applied owing to its efficiency and cost-effectiveness. This study extends the application of MPC test principles, commonly utilized for turbine oils, to measure insoluble contaminants generated by degraded hydraulic fluids. Adhering to the ASTM D7843-21 standard, which stipulates the precision of this testing method for turbine oils is contingent upon the sample’s incubation period, our investigation focuses on exploring modifications to the standard 72-hour incubation period. We aim to assess the viability of shortening or extending this duration for conducting MPC tests on used hydraulic fluids, thereby potentially enhancing the precision and relevance of MPC tests in hydraulic fluid analysis.

Non-destructive techniques (NDT) have enhanced their usefulness in the field of cultural heritage protection and have become valuable tools for the investigation of composing materials, as well as for the detection of alteration and degradation of various structures. In the current study, non-destructive techniques, based on digital photography processing and analysis (digital photography-Vis/UVF, portable digital optical microscopy, colorimetry, infrared thermography), are used for the examination of three composite contemporary artworks created on photosensitized cement. This approach was applied to a series of composite works (photosensitized cement surfaces) in order to understand the craftmanship of the artist, document the materials used and assess the overall condition of the artworks. The techniques and methods applied can be used as a benchmark for the study of similarly complex artworks and for conservation and restoration planning. This comparative study has shown that, although the three artworks under examination are composed of alike materials (cement mortar, plaster, photosensitive emulsion), they exhibit distinct condition states, which can be attributed to variations in the artist technique and application, as well as to their exposure to different environmental conditions.

Abstract Currently, most of the methods for mineral materials analysis generate secondary pollution, which is detrimental to human health. For instance, traditional methods for sphalerite analysis in the zinc (Zn) smelting industry including chemical titration, atomic absorption spectrometry, and inductively coupled atomic emission spectroscopy. Colored indicators and toxic heavy metals are used in the analytical processes, causing severe pollution. For some methods, liquid is transformed into gaseous plasma, which is more dangerous to human health. Due to large quantities of sphalerite being used, secondary pollution cannot be ignored. This study proposes a green analysis method for the detection of sphalerite based on colorimetry, which does not generate secondary pollution. The results show that the strong substitution ability of iron (Fe) for Zn contributes to their inverse correlation in contents. The lattice parameters decrease with the increasing Fe content, resulting in a darker coloration. Here, key colorimetry parameters of L*, a*, and b* show clear linear correlations with the Zn and Fe contents. Compared with traditional approaches, this new method is environmental friendly with high sensitivity and accuracy. The relative error and relative standard deviation were less than 10% and 5%, respectively. This study provides a significant reference for nonpollution determination of other mineral materials.

Histopathological analysis is one of the primary pillars in clinical diagnostics. The efforts to implement optical techniques aim at alleviating the burden of delivering timely and accurate diagnoses. We have explored the potential application of unstained tissue slides’ autofluorescence to differentiate collagen-related skin degenerative diseases, such as psoriasis, lupus erythematosus, scleroderma, and Syndrome of Raynaud. This exploration involved two techniques: fluorescence microscopy combined with colorimetric analysis and synchronous fluorescence spectroscopy. We addressed the main characteristic peculiarities of the examined samples and discussed the evaluation of potential classification parameters along with their diagnostic values.

Simple analytical devices suitable for the analysis of various biochemical and immunechemical markers are highly desirable and can provide laboratory diagnoses outside standard hospitals. This study focuses on constructing an easily reproducible do-it-yourself ELISA plate reader biosensor device, assembled from generally available and inexpensive parts. The colorimetric biosensor was based on standard 96-well microplates, 3D-printed parts, and a smartphone camera as a detector was utilized here as a tool to replace the ELISA method, and its function was illustrated in the assay of TNFα as a model immunochemical marker. The assay provided a limit of detection of 19 pg/mL when the B channel of the RGB color model was used for calibration. The assay was well correlated with the ELISA method, and no significant matrix effect was observed for standard biological samples or interference of proteins expected in a sample. The results of this study will inform the development of simple analytical devices easily reproducible by 3D printing and found on generally available electronics.

This paper explores the intersection of colorimetry and biomimetics in textile design, focusing on mimicking natural plant colors in dyed textiles via instrumental colorant formulation. The experimental work was conducted with two polyester substrates dyed with disperse dyes using the exhaustion process. Textiles dyed with different dye colors and concentrations were measured in a spectrophotometer and a database was created in Datacolor Match Textile software version 2.4.1 (0) with the samples’ colorimetric properties. Colorant recipe formulation encompassed the definition and measurement of the pattern colors (along four defined natural plants), the selection of the colorants, and the software calculation of the recipes. After textile dyeing with the lowest expected CIELAB color difference (ΔE*) value recipe for each pattern color, a comparative analysis was conducted by spectral reflectance and visual assessment. Scanning electron microscopy and white light interferometry were also used to characterize the surface of the natural elements. Samples dyed with the formulated recipe attained good chromatic similarity with the respective natural plants’ colors, and the majority of the samples presented ΔE* between 1.5 and 4.0. Additionally, recipe optimization can also be conducted based on the colorimetric evaluation. This research contributes a design framework for biomimicking colors in textile design, establishing a systematic method based on colorimetry and color theory that enables the reproduction of nature’s color palette through the effective use of colorants.

(1) Background: This paper illustrates an innovative methodological approach chosen to study and map the colors of the medieval wall painting of Santa Maria Antiqua in the Roman Forum, one of the pilot sites of the EHEM project (Enhancement of Heritage Experiences: The Middle Ages). Digital Layered Models of Architecture and Mural Paintings over Time). (2) Methods: Two methods were employed to gather information about colors and mapping. Specifically, colorimetry was utilized for spot measurements, and hypercolorimetric multispectral imaging (HMI) was employed to map the same colors sampled through colorimetry. (3) Results: Chromatic data for all colors in the wall paintings were obtained in the CIELAB color space. Additionally, chromatic similarity maps were generated using the innovative HMI system, a multispectral imaging technique capable of obtaining color data information through advanced calibration software named SpectraPick® (Version 1.1). This comprehensive approach facilitates a thorough understanding of color characteristics and distribution. (4) Conclusions: The color measurements and mapping represent significant advancements in the interpretation of medieval wall paintings, which are often fragmentary and stratigraphically complex. This research sheds new light on the colors used and enhances our understanding of the original appearance of the iconographic patterns. Furthermore, it enables the reconstruction of colors that closely resemble the originals.

Gold nanoparticle (AuNP) fabrication via the oxidation of D-glucose is applied for detecting two foodborne pathogens, Enterococcus faecium (E. faecium) and Staphylococcus aureus (S. aureus). D-glucose is used as a reducing agent due to its oxidation to gluconic acid by sodium hydroxide (NaOH), resulting in the formation of AuNPs. Based on this mechanism, we develop AuNP-based colorimetric detection in conjunction with loop-mediated isothermal amplification (LAMP) for accurately identifying the infectious bacteria. Here, Au+ ions bind to the base of double-stranded DNA. In the presence of D-glucose and NaOH, the LAMP amplicon-Au+ complex maintains its bound state at 65 °C for 10 min while it is reduced to AuNPs in a dispersed form, exhibiting a red color. We aimed to pre-mix D-glucose with LAMP reagents before amplification and induce successful colorimetry without inhibiting amplification to simplify the experimental process and decrease the reaction time. Therefore, the entire process, including LAMP and colorimetric detection, is accomplished in approximately 1 h. The limit of detection of E. faecium and S. aureus is confirmed using the introduced method as 101 CFU/mL and 100 fg/μL, respectively. We expect that colorimetric detection using D-glucose-mediated AuNP synthesis offers an application for simple and immediate molecular diagnosis.

In this paper, a study is performed in order to achieve a process that successfully respects the colour integrity of photogrammetry models of cultural heritage pieces. As a crucial characteristic of cultural heritage documentation, the colour of the pieces—as a valuable source of information—needs to be properly handled and preserved, since digital tools may induce variations in its values, or lose them to a degree. Different conditions for image acquisition schemes, RGB value calculation, calibration and photogrammetry have been combined and the results measured, so the adequate procedure is found. Control over all colour transformations is enforced, with blending operations during the texture generation process being the only unpredictable step in the pipeline. It is demonstrated that an excellent degree of colour information preservation can be achieved when applying said control on the factors of acquisition and colour digitalization, inclusive deciding their parameters. This paper aims to serve as guidelines of a correct handling of colour information and workflow so cultural heritage documentation can be performed with the highest degree of colour fidelity, covering the gap of non-existing standard procedure or conditions to perform an optimum digital cultural heritage colour modelling.

In this study, the amylose contents in 24 commercial foxtail millet samples from major production provinces in China were determined by four different methods, namely, the improved national standard method (GB/T 15683-2008), the spectrophotometric method (NY/T 2639-2014) recommended by China’s agricultural authority, the dual-wavelength method, and the concanavalin A (Con A) method. The results of these methods were in the following decreasing order: improved GB/T 15683-2008 ≈ dual-wavelength > NY/T 2639-2014 > Con A. The correlation coefficient between the results of improved GB/T 15683-2008 and those of NY/T 2639-2014 was highest, 0.752 (P = 0), the former being about 1.41 times higher than the latter, which could allow simple prediction of the amylose content of foxtail millet. In conclusion, the improved GB/T 15683-2008 method, the dual-wavelength method and the NY/T 2639-2014 (× 1.41) method can be used to accurately determine the content of amylose in foxtail millet while greatly reducing sample testing time.

Food products change their quality during storage not only under the external impact, but also because they are complex in composition. As a result, food scientists look for new methods to control these internal changes. The research objective was to describe the changes in the physicochemical properties of apple puree during storage at elevated temperatures (40–60°C) and link them with the changes in the sensory profile. The study featured homogenized apple puree packaged in composite material and heated up to 40, 50, and 60°C. The colorimetric studies were conducted at 45°/0°, light source D65. The proton relaxation time and the water diffusion coefficient (impulse gradient method) were studied at a frequency of 20 MHz. The analysis of molecular dynamics involved the method of electron paramagnetic resonance of spin probes. The samples were cooled down to –70°C to measure the content of non-crystallizing water by the method of differential scanning calorimetry. The color change rate was constant and followed the zero-order kinetic reaction equation with an activation energy of 92 kJ/mol. The changes in color, proton relaxation, and sensory properties correlated when the samples were stored at 50 and 60°C. The analysis of the magnetic relaxation time, the diffusion coefficient of water, and the content of non-crystallizing water indicated that the main changes in the physical structure of the puree during heat treatment occurred as a result of the aggregation of apple cell fragments. These findings were confirmed by the optical microscopy. A prolonged exposure to 40–60°C affected the color, the relaxation of water protons, and the size of aggregates of apple cell fragments. It also affected the amount of water that did not crystallize at –70°C. The correspondence between the values of the activation energies was determined by the methods of colorimetry and proton relaxation. Therefore, the coloration and the water changes depended on the same processes. These physical and chemical properties can be used for quantitative assessment of apple puree under thermal treatment.

The CRISPR (clustered regularly interspaced short palindromic repeats)/Cas (CRISPR associated) system has proven to be a powerful tool for nucleic acid detection due to its inherent advantages of effective nucleic acid identification and editing capabilities, and is therefore known as the next-generation of molecular diagnostic technology. However, the detection technologies based on CRISPR/Cas systems require preamplification of target analytes; that is, target gene amplification steps through isothermal amplification or PCR before detection to increase target analyte concentrations. This creates a number of testing limitations, such as extended testing time and the need for more sophisticated testing instruments. To overcome the above limitations, various amplification-free assay strategies based on CRISPR/Cas systems have been explored as alternatives, which omit the preamplification step to increase the concentrations of the target analytes. Nanozymes play a pivotal role in enhancing the sensitivity of CRISPR-based detection, enabling visual and rapid CRISPR assays. The utilization of nanozyme exceptional enzyme-like catalytic activity holds great promise for signal amplification in both electrochemical and optical domains, encompassing strategies for electrochemical signal sensors and colorimetric signal sensors. Rather than relying on converting a single detection target analyte into multiple analytes, these methods focus on signal amplification, the main mechanism of which involves the ability to form a large number of reporter molecules or to improve the performance of the sensor. This exploitation of nanozymes for signal amplification results in the heightened sensitivity and accuracy of detection outcomes. In addition to the strategies that improve sensor performance through the application of nanozymes, additional methods are needed to achieve visual signal amplification strategies without preamplification processes. Herein, we review the strategies for improving CRISPR/Cas systems that do not require preamplification, providing a simple, intuitive and preamplification-free CRISPR/Cas system detection platform by improving in-system one-step amplification programs, or enhancing nanozyme-mediated signal amplification strategies.

Statement of problem: The relation between cement color and abutment substrate material and the corresponding effect on the color accuracy of high-transparency pre-colored zirconia (HT-Zr) remains unclear. Purpose: This in-vitro study aimed to investigate the difference in color accuracy when the HT-Zr is bonded to different materials-based substrates with differently colored resin cement. Materials and methods: Vita A1 shade HT-Zr with 1 mm thickness was used as the testing sample. The samples were first placed on zirconia (ZR), tooth color resin (CR), and metallic (MT) abutment substrates. Subsequently, four differently colored cements (translucent (TR), bleach, opaque, and A2 shade (A2)) were used for bonding HT-Zr onto the substrate, and the non-bonded group was used as the control group (CG). There were 15 groups in total (n = 10 per group). A digital colorimeter was used to obtain Commission Internationale de l’Eclairage (CIELab) color parameters. The translucency parameter (TP00) of the substrate and sample, as well as color difference (ΔE00) and chroma (C) between the different groups were calculated. Additionally, the ΔE00 and TP00 were compared with the moderately unacceptable match of ΔE00 = 3.6. The statistical analysis was conducted using ANOVA and Tukey HSD post-hoc test (α = 0.05). Results: HT-Zr exhibited high translucency (TP00 = 11.02 ± 0.18), and the mean ΔE00 of the testing samples ranged between 2.18 ± 0.20 and 13.14 ± 0.31. The ZR-CG and MT-A2 groups showed the highest and lowest lightness separately. The CR-CG group exhibited the highest C, and the ΔE00 was lower than that of 3.6. The MT-TR group showed the lowest C and the highest ΔE00. The inter-group comparison revealed that the ΔE00 for different cement is mostly lower than the acceptable color match of 1.0; moreover, the ΔE00 for all the substrates, excluding the CG group, is higher than 3.6. Conclusions: The abutment substrate materials and the cement color should be considered with caution when using HT-Zr, with the effect of abutment substrate materials being more apparent in color accuracy. HT-Zr restorations are not recommended for discolored or bleached abutments but only for natural-colored abutments to achieve the optimal color appearance.

A broad spectrum of application fields, including human and animal health, food safety and environmental monitoring, require performing real time, on-field chemical determinations, a concept known as point-of-need testing (PONT). In the case of infectious diseases, it allows for early diagnosis, which usually enables better treatment options for the patient, and permits early outbreak detection and intervention with proper control measures. PONT solutions are usually developed on microfluidic chips, preferably with no extra equipment, as to lower their cost, ease their delivery and portability. However, equipment-free PONT is not always feasible, since off-chip operations (e.g., pumping or heating) might be required and provided by the so-called analyzers. A typical example is the hardware for optical reading, which is the subject of this perspective article. Firstly, the state-of-the-art is briefly analyzed considering the solutions provided by both academy and industry. Special emphasis is made on the smartphone-based approaches that use no additional hardware (add-ons) for optical reading. Smartphones are the straightforward option, since they can replace a number of operations typically done by analyzers. The issues arising from using smartphones without add-ons are classified into variability sources and technical challenges. Finally, a set of methods for dealing with these challenges is proposed and briefly discussed. Simpler systems will be more easily adopted by more users, for a broader range of application cases, and will let PONT be a more powerful tool for improving disease diagnosis and outbreak management.

Background: Hydrogen sulfide (H2S), an endogenous gasotransmitter, has potential applications in several conditions. However, its quantification in simulated physiological solutions is a major challenge due to its gaseous nature and other physicochemical properties. Aim: This study was designed to compare four commonly used H2S detection and quantification methods in aqueous solutions. Methods: The four techniques compared were one colorimetric, one chromatographic and two electrochemical methods. Results: Colorimetric and chromatographic methods quantified H2S in millimolar and micromole ranges, respectively. The electrochemical methods quantified H2S in the nanomole and picomole ranges and were less time-consuming. Conclusion: The H2S quantification method should be selected based on the specific requirements of a research project in terms of sensitivity, response time and cost-effectiveness.

Classification of cannabis samples as hemp- or drug-type is an ever-increasing problem worldwide. Colorimetric tests and infrared spectroscopy were selected and critically compared among the available techniques. Cannabis samples with different THC and CBD concentration were analyzed by paper-based analytical devices (µPAD) using the 4-aminophenol colorimetric reaction, attenuated total reflectance mid infrared spectroscopy (ATR-MIR), and diffuse reflectance near infrared spectroscopy (DR-NIR). For the µPAD analysis, cannabis samples were extracted with methanol and later mixed with reagents to develop the colored complex. On the other hand, MIR and NIR spectra were obtained directly on raw samples, and partial least square discriminant analysis (PLS-DA) was used for cannabis classification. All the selected methodologies successfully discriminate between hemp-type and drug-type samples, being suitable to be used in-field. Additionally, assayed methodologies together a reference gas chromatography mass spectrometry (GC–MS) were evaluated and compared from a Green Analytical point of view using the AGREE criteria.

This study demonstrates a novel colorimetric method for clenbuterol (CLB) detection based on the peroxidase-like activity of SiO2-coated Fe3O4 nanoparticles (Fe3O4@mSiO2) modified with montmorillonite (MMT) and sodium dodecyl sulfate (SDS), namely, Fe3O4@mSiO2@MMT-SDS. Fe3O4@mSiO2@MMT-SDS nanoparticles were prepared by modifying Fe3O4@mSiO2 with MMT and SDS to impart negative charges to the particle surfaces. The structural properties, steady-state kinetics, catalytic performance, and reaction conditions of the as-prepared nanoparticles were analyzed. Fe3O4@mSiO2@MMT-SDS nanoparticles exhibited excellent dispersion and enzyme-like activity, which improved the affinity with substrate (TMB and H2O2) for the catalytic oxidation of CLB by H2O2, turning the solution blue in the presence of the 3,3ʹ, 5,5ʹ-tetramethylbenzidine chromogen. Under optimal reaction conditions, a strong linear correlation between the absorbance of solution and CLB concentration (R2 = 0.9983) was observed. Here, the limit of detection, spike recovery, and relative standard deviation were 9.6 × 10-9 mol·L-1, 94.2 %–102.2 %, and 2.2 %–4.4 %, respectively. The proposed method is a simple, fast, cost-efficient, and sensitive assay, which can be used to rapidly and accurately screen CLB in pork and animal feeds.

The entrapment of the sensitive reagent 5-(2′-bromophenylazo)-6‑hydroxy-pyrimidine-2,4‑dione (BPAHPD) in a silica sol-gel thin film coated on a glass substrate has been investigated for the development of a highly sensitive and selective optode for the determination of lead ions. The fabrication of thin films requires tetraethoxysilane as a precursor, a sol-gel pH of 2.75, a water: alkoxide ratio of 5:1, and a BPAHPD concentration of 4.0 × 10–4 M. The effect of sol-gel parameters on the optode's sensing performance was investigated. The fabricated optode is utilized for lead ion detection over a dynamic range of 4.00–144 ng mL–1 with detection and quantification limits of 1.20 and 3.95 ng mL–1, respectively. It gave repeatable results with relative standard deviation (RSD) values of 1.90% and 1.15% for lead concentrations of 40.0 and 80.0 ng mL–1, respectively, and a response time of two minutes. Through capturing BPAHPD in a sol-gel matrix and appropriately modifying the structure of doped sol-gel, interference studies have determined that lead exhibits a high degree of selectivity. To ascertain total lead, Pb4+ was reduced to Pb2+ using a few drops of 6.00 M hydrochloric acid and a freshly prepared sodium azide solution of 2.50 % (w/v). The optode can be easily regenerated with 0.15 M of nitric acid solution. The optode has complete reversibility. Optode detection of lead in diverse vegetable, food, biological, water, and soil samples yielded favorable results when compared to other techniques.

Interstitial fluid is a readily accessible source of biomarkers for various diseases, providing a less invasive and more convenient option than traditional blood or tissue sampling methods. Microneedle-based point-of-care testing devices have gained significant interest due to their potential for direct detection of target analytes in ISF, accomplished through minimally invasive penetration of the stratum corneum. Thus, microneedle-based devices can be considered as adhesive tools for diagnostic sensing and therapeutic drug administration. Microneedle-based colorimetric and fluorescence sensing has the potential to revolutionize disease diagnosis and monitoring, offering a rapid, highly sensitive, specific, and cost-effective alternative to traditional methods. These devices enable the detection of low levels of biomarkers in the collected fluid, which is particularly important in situations requiring prompt diagnosis and treatment. This review covers the types of microneedles and their fabrication methods, the detection principles of microneedle-based colorimetric and fluorescence sensing, as well as their key applications, advantages, and limitations. Additionally, the review explores ways to overcome current limitations and improve the performance, as well as future perspectives for the development of microneedle-based devices.