Search Results (42)

This study evaluated the potential of a miniaturized portable near-infrared spectroscopy (NIRS) device for the non-destructive prediction of the physicochemical and functional quality attributes of red berries. A total of 145 samples from three berry species (aronia, haskap and goji), representing different harvest years and ripening stages, were analyzed. Spectra were acquired over the 908–1676 nm range using a MicroNIR™ 1700 OnSite-W spectrophotometer, and partial least squares regression models were developed to predict total soluble solids, moisture content, pH, total phenolic content and antioxidant capacity. The calibration models achieved coefficients of determination in cross-validation (R²CV) ranging from 0.83 to 0.92, with Root Mean Square Error of Cross-Validation (RMSECV) between 0.281 for pH and 2.085 g Trolox kg⁻¹ FW for antioxidant capacity. External validation confirmed the robustness of the models, yielding R²EV values between 0.76 and 0.88 and Root Mean Square Error of Validation (RMSEV) ranging from 0.381 for pH to 2.095% for moisture content. The highest predictive performance was obtained for total soluble solids (R²EV = 0.88; RMSEV = 1.391), followed by moisture content, pH and antioxidant capacity, whereas total phenolic content showed the lowest predictive accuracy (R²EV = 0.76; RMSEV = 1.914 mg GAE g⁻¹ FW). The Residual Prediction Deviation (RPD) and Range Error Ratio (RER) values further supported the practical applicability of the models for approximate quantitative prediction. Overall, these results demonstrate that portable NIRS is a rapid, non-destructive and reliable tool for the integrated assessment of the physicochemical and functional quality attributes of emerging red berry species. Full article

This study aimed to investigate the repair performance of these materials subjected to different surface treatment protocols using combined mechanical and optical evaluations. Four resin-matrix materials were evaluated: two CAD/CAM materials (HIPC Plus and GC Cerasmart) and two additively manufactured resins (VarseoSmile TriniQ and CrownTec). Standardized disc specimens were fabricated and thermocycled prior to repair. Three surface treatments were applied: airborne particle abrasion (APA), tribochemical silica coating (TSC) with silane, and laser treatment (LT). Micro-shear bond strength (µSBS) was measured using composite cylinders bonded to treated surfaces. For optical evaluation, standardized cavities were restored with composite resin, and color measurements were obtained at baseline (T0) and after aging (T1) using a spectrophotometer. Color mismatch and color stability were calculated. Data were analyzed using two-way ANOVA and Tukey tests (α = 0.05). Material type and surface treatment significantly affected µSBS (p < 0.001). CAD/CAM materials had higher bond strength than additively manufactured ones. The TSC group showed the highest µSBS. Aging increased color mismatch, with post-aging ΔE00 values surpassing clinical thresholds. Additively manufactured materials experienced greater color changes. Repair performance depends on manufacturing method and surface treatment. The higher bond strength in the TSC group likely results from silica coating and silanization. CAD/CAM materials showed better optical stability. Full article

Several studies have attempted to define the performance of most commercially available shade guides. The purpose of the present study was to compare the coverage errors of three commercial shade guides for a selected Greek population and to investigate whether there is a difference between the coverage errors of the three shade guides for different types of anterior teeth of the selected population. Adult participants with healthy maxillary anterior teeth were recruited for color assessment. Color coordinates were measured for central incisors, lateral incisors, and canines of 212 individuals. Tooth shades were measured at the middle third using the Spectroshade Micro spectrophotometer, and three shade guide systems (Ivoclar, Vitapan Classical, and 3D Master) were evaluated under standardized conditions for comparison. The coverage errors of Ivoclar and Vitapan classical shade guides were not significantly different from each other for all teeth and for the three tooth types separately. However, 3D Master shade guide exhibited significantly lower coverage errors for all teeth and for the three tooth types separately (p < 0.001). 3D Master performed better than the other two shade guides for shade matching with natural dentition in the selected population. Full article

Cr-doped diamond-like carbon (DLC) films were formed on silicon and glass substrates by magnetron sputtering (MS). The surface morphology, elemental composition, bonding structure, and transparency of the as-deposited films were analyzed by atomic force microscopy (AFM), the energy-dispersive X-ray spectroscopy (EDS), multiwavelength micro-Raman spectrometer, and UV-VIS-NIR spectrophotometer. The study revealed that the oxygen concentration in the Cr-DLC films increased as the Cr content increased. The surface roughness of the films was slightly reduced when the Cr content was ~9.2 at.%, and further increase in the Cr content up to 13.1 at.% stimulated the growth of the highest-roughness Cr-DLC films. The micro-Raman analysis showed that the G peak position shifted to a higher wavenumber, and the sp² bond fraction increased as the Cr concentration in the DLC films rose. The optical transmittance of the Cr-DLC films was reduced by up to 30% compared to DLC coatings due to the increased graphitization process caused by chromium addition. Full article

This study aimed to evaluate the micro-nanostructure and color changes of dental enamel after treatment with new gel formulations containing papain or bromelain. Eighty caries-free, extracted human teeth were randomly divided into two groups (n = 40) and stained by immersion in either coffee or Tedi juice for 4 h daily over five consecutive days. After staining, the samples were washed and stored in artificial saliva at 37 °C. The stained samples were then treated with four different whitening gels (GC, G1, G2, and Opalescence 15%) for 4 h daily. Following each treatment, the samples were rinsed and stored in artificial saliva. Color changes were measured using a digital spectrophotometer to assess CIEL*a*b* ΔE* and the Whiteness index (WI). The enamel micro-nanostructure was analyzed using SEM and AFM. Data were statistically analyzed using one-way ANOVA followed by Tukey’s HSD test. The results showed that gels containing papain and bromelain were more effective than the commercial gel in removing stains. SEM and AFM analysis indicated that papain was particularly effective for removing coffee stains, while bromelain was better for stains from natural juices. Healthy enamel has a Ra value of approximately 10 nm, which increases to about 40 nm after staining. Papain restored enamel roughness to approximately 8 nm for coffee stains and bromelain restored it to 11 nm for juice stains, delivering optimal results, while commercial gel ensures a roughness of about 15 nm after stain removal. CIELAB reveals notable changes in ΔE and WI after bleaching, revealing that papain gel is optimal for coffee stain removal and bromelain gel is optimal for natural juice stains. In conclusion, dental stains should be assessed by a dentist to determine the most suitable gel for achieving optimal results. Full article

Near-infrared spectroscopy (NIRS) was evaluated to trace the high hydrostatic pressure (HHP) processing and preservation temperature (4 °C vs. 20 °C) over the course of a long term in vacuum-packaged Iberian dry-cured tenderloin (Iliopsoas et psoas minor). Spectra were obtained from a total of 298 samples, without opening the package, using a handheld MicroNIR^TM 1700 OnSite-W microspectrophotometer (908.1 nm–1676.2 nm) (VIAVI Solutions Inc., United States). The discriminant models were developed by means of partial least squares-discriminant analysis (PLS-DA). The models obtained were capable of correctly classifying more than 60% of the samples according to their HHP processing, while almost 100% of the samples were correctly classified according to the temperature at which the samples were preserved. Thus, NIRS could help to support the traceability of treatments that represent a high added value to the product, such as HHP in premium Iberian dry-cured products. Full article

This study aimed to evaluate the change in enamel color and surface micro-hardness following the use of resin-infiltration concept material (ICON) and casein phosphopeptide-amorphous calcium fluoride phosphate (CPP-ACFP) remineralizing agent. Fifty-four extracted human third molars were collected and randomly divided into three groups: group A: control with no surface treatment; group B: treated using ICON; and group C: treated using CPP-ACFP. The change in color and micro-hardness of the enamel surface were measured using spectrophotometer and Vickers hardness number, respectively. The measurements were taken at three timelines; baseline (BL), after demineralization (DM), and after surface treatment (TX). The three groups showed no significant differences in enamel color change after demineralization (p < 0.05). However, after surface treatment in relation to the baseline, groups B and C had a significant increase in color change compared to the control group (p < 0.05), and group B showed a statistically significant increase in enamel color changes compared to group C. Additionally, all groups exhibited a significant reduction in enamel micro-hardness after demineralization in comparison to their baseline (p < 0.05). Group C showed a significant increase in micro-hardness after surface treatment compared to groups A and B (p < 0.05), while group B showed a significant decrease in enamel micro-hardness compared to groups A and C (p < 0.05). These findings suggest that teeth treated with CPP-amorphous calcium fluoride phosphate (CPP-ACFP) show a significant improvement in enamel surface color after demineralization compared to the teeth treated with resin infiltration (ICON) and the non-treated teeth. Additionally, enamel surfaces treated with CPP-ACFP show significant enamel hardness regaining, while resin infiltration (ICON) compromises enamel surface hardness. Full article

Background/Objectives: Despite the increasing use of chromatic intraoral scanners, color determination is often performed visually, offering poor reliability and validity. In this study, we aimed to compare the reliability and validity of the tooth shade determination tool of an intraoral scanner (Trios3 Color) with that of two dental spectrophotometers (VITA Easyshade Advance 4.0 and SpectroShade Micro) and with visual determination using the VITA 3D-Master shade guide. Methods: In vivo tooth shade determination was performed on 33 participants using positioning splints for the right central incisor. Repeated measurements assessed the reliability in determining the percentage agreement with VITA 3D-Master shades. VITA Easyshade measurements were used as reference values for validity. The metric value Delta E (ΔE) in the International Commission on Illumination L*a*b* color space was compared to the reference, with ΔE greater than 1 indicating visible differences and a maximum value of ΔE 6.8 being clinically acceptable. Results: The reliabilities of VITA Easyshade, the intraoral scanner, and SpectroShade Micro were 75.8%, 87.9%, and 89.9%, respectively. The visual method had an agreement rate of 20.6%. Validity values, compared with the reference value, were ΔE 3.8 (clinically acceptable), 8.3, and 7.4 (the latter two both being clinically unacceptable) for the intraoral scanner, area-measuring device, and visual method, respectively. Conclusions: The intraoral scanner is a reliable and valid tool for tooth shade determination and is superior to the visual method in both aspects. Full article

Objective: The purpose of this study was to evaluate the chromatic adaptability and color stability of two different composite resins, Omnichroma and Estelite Bulk-Fill Flow, in Class V restorations at different times. Materials and methods: Standardized Class V cavities were prepared on the labial surface of 34 extracted intact and noncarious human permanent molars. The dental elements were randomly divided into two groups according to the resin composite material. Group 1 was restored with Omnichroma (Tokuyama Dental Corporation Inc., Tokyo, Japan) and Group 2 was restored with Estelite BulkFill Flow Universal (Tokuyama Dental Corporation Inc., Tokyo, Japan). Color properties were assessed using a spectrophotometer, SpectroShadeTM Micro (MHT Optic Research, Niederhasli, Switzerland), at baseline (T0), immediately after Class V restoration (T1), 24 h after restoration (T2) and after thermocycling (T3) (ISO/TS 11405, 2015 protocol). Color difference (ΔE) was analyzed with a Student’s t-test and a Wilcoxon–Mann–Whitney test to evaluate the differences, in terms of chromatic adaptability, between the two materials (inter-group analysis) while Kruskal–Wallis test e Two-way ANOVA statistical tests were used to evaluate the color stability of each material over time (intra-group analysis). Results: Regarding the inter-group analysis, there were no statistically significant differences between the two materials in all the comparisons: T0–T1 (p = 0.9025), T0–T2 (p = 0.2779), T0–T3 (p = 0.4694). Moreover, both groups showed an average ΔE > 2. In the intra-group analysis, no statistically significant differences were observed in either Group 1 (p = 0.954) or Group 2 (p = 0.8654). Conclusions: The in vitro color matching, assessed by spectrophotometry, of the two tested resin composites does not vary at different time intervals. Furthermore, even though both composites use different mechanisms to produce the color the human eye perceives, they show very similar chromatic adaptability. Full article

A novel microfluidic ractopamine (RAC) detection platform consisting of a microfluidic RAC chip and a smart analysis device is proposed for the determination of RAC concentration in meat samples. This technology utilizes gold nanoparticles (AuNPs) modified with glutamic acid (GLU) and polyethyleneimine (PEI) to measure RAC concentration in food products. When RAC is present, AuNPs aggregate through hydrogen bonding, causing noticeable changes in their optical properties, which are detected using a self-built UV–visible micro-spectrophotometer. Within the range of 5 to 80 ppb, a linear relationship exists between the absorbance ratio (A_693nm/A_518nm) (Y) and RAC concentration (X), expressed as Y = 0.0054X + 0.4690, with a high coefficient of determination (R² = 0.9943). This method exhibits a detection limit of 1.0 ppb and achieves results within 3 min. The practical utility of this microfluidic assay is exemplified through the evaluation of RAC concentrations in 50 commercially available meat samples. The variance between concentrations measured using this platform and those determined via liquid chromatography–tandem mass spectrometry (LC-MS/MS) is less than 8.33%. These results underscore the viability of the microfluidic detection platform as a rapid and cost-effective solution for ensuring food safety and regulatory compliance within the livestock industry. Full article

Surface enhanced Raman spectroscopy (SERS) is gaining importance as sensing tool. However, wide application of the SERS technique suffers mainly from limitations in terms of uniformity of the plasmonics structures and sensitivity for low concentrations of target analytes. In this work, we present SERS specimens based on periodic arrays of 3D-structures coated with silver, fabricated by silicon top-down micro and nanofabrication (10 mm × 10 mm footprint). Each 3D-structure is essentially an octahedron on top of a pyramid. The width of the top part—the octahedron—was varied from 0.7 µm to 5 µm. The smallest structures reached an analytical enhancement factor (AEF) of 3.9 × 10⁷ with a relative standard deviation (RSD) below 20%. According to finite-difference time-domain (FDTD) simulations, the origin of this signal amplification lies in the strong localization of electromagnetic fields at the edges and surfaces of the octahedrons. Finally, the sensitivity of these SERS specimens was evaluated under close-to-reality conditions using a portable Raman spectrophotometer and monitoring of the three vibrational bands of 4-nitrobenzenethiol (4-NBT). Thus, this contribution deals with fabrication, characterization and simulation of multiscale 3D-structures with SERS activity. Full article

Background and Objectives: Primary outcome: To assess the level of agreement between the objective and subjective methods for recording gingival colour in each area of the gingiva. Secondary outcome: To compare performance of the subjective visual method of gingival colour selection by a male observer and a female observer. Materials and Methods: A chromatic study was conducted on a total of 101 participants, in five gingival zones, from the free gingival margin to the mucogingival line, using a SpectroShade Micro spectrophotometer for the objective method and 21 ad hoc ceramic gingival shade tabs for the subjective method. A man and a woman of the same age, with the same amount of clinical experience in dentistry, selected the tab that most resembled the colour of participants’ gingiva. The “chromatic error” was then assessed by calculating the colour difference (using the Euclidean and CIEDE2000 formulae) between the CIELAB coordinates of the shade tab selected and the objective coordinates of the gingiva. The unweighted Kappa coefficient was used to calculate the level of agreement between observers. Results: For the male observer, the mean chromatic errors varied between ΔEab* 10.3 and 13.1 units, while for the female observer, the mean errors varied between ΔEab* 11.1 and 12.8: these differences were not statistically significant. Similarly, no statistically significant differences were found between the mean chromatic errors for the five gingival zones in either the male operator (p = 0.100) or the female operator (p = 0.093). The minimum level of agreement (unweighted Kappa) between the observers ranged from 0.1 to 0.4. Conclusions: Subjective selection of gingival colour was very inaccurate, by both the male observer and the female observer, for any area of the gingiva, with no differences identified between them. The level of agreement between the observers was low. These findings suggest that gingival colour should not be determined using solely subjective methods, given that the chromatic errors significantly exceeded the clinical acceptability threshold for gingiva (4.1 units for ΔEab* and 2.9 units for ΔE00). Both observers showed a tendency to select gingival shade tabs that were redder and bluer than the objective colours. Full article

Accurately identifying adulterants in agriculture and food products is associated with preventing food safety and commercial fraud activities. However, a rapid, accurate, and robust prediction model for adulteration detection is hard to achieve in practice. Therefore, this study aimed to explore deep-learning algorithms as an approach to accurately identify the level of adulterated coconut milk using two types of NIR spectrophotometer, including benchtop FT-NIR and portable Micro-NIR. Coconut milk adulteration samples came from deliberate adulteration with corn flour and tapioca starch in the 1 to 50% range. A total of four types of deep-learning algorithm architecture that were self-modified to a one-dimensional framework were developed and tested to the NIR dataset, including simple CNN, S-AlexNET, ResNET, and GoogleNET. The results confirmed the feasibility of deep-learning algorithms for predicting the degree of coconut milk adulteration by corn flour and tapioca starch using NIR spectra with reliable performance (R² of 0.886–0.999, RMSE of 0.370–6.108%, and Bias of −0.176–1.481). Furthermore, the ratio of percent deviation (RPD) of all algorithms with all types of NIR spectrophotometers indicates an excellent capability for quantitative predictions for any application (RPD > 8.1) except for case predicting tapioca starch, using FT-NIR by ResNET (RPD < 3.0). This study demonstrated the feasibility of using deep-learning algorithms and NIR spectral data as a rapid, accurate, robust, and non-destructive way to evaluate coconut milk adulterants. Last but not least, Micro-NIR is more promising than FT-NIR in predicting coconut milk adulteration from solid adulterants, and it is portable for in situ measurements in the future. Full article

Protein adulteration is a common fraud in the food industry due to the high price of protein sources and their limited availability. Total nitrogen determination is the standard analytical technique for quality control, which is incapable of distinguishing between protein nitrogen and nitrogen from non-protein sources. Three benchtops and one handheld near-infrared spectrometer (NIRS) with different signal processing techniques (grating, Fourier transform, and MEM—micro-electro-mechanical system) were compared with detect adulteration in protein powders at low concentration levels. Whey, beef, and pea protein powders were mixed with a different combination and concentration of high nitrogen content compounds—namely melamine, urea, taurine, and glycine—resulting in a total of 819 samples. NIRS, combined with chemometric tools and various spectral preprocessing techniques, was used to predict adulterant concentrations, while the limit of detection (LOD) and limit of quantification (LOQ) were also assessed to further evaluate instrument performance. Out of all devices and measurement methods compared, the most accurate predictive models were built based on the dataset acquired with a grating benchtop spectrophotometer, reaching R²P values of 0.96 and proximating the 0.1% LOD for melamine and urea. Results imply the possibility of using NIRS combined with chemometrics as a generalized quality control tool for protein powders. Full article

An efficient catalyst is key to achieving the synthesis of electrochemical ammonia and improving safety. In this work, using biomass walnut shell as a carbon source and sodium thiosulfate as a sulfur source, sulfur-modified walnut shell-derived carbon material was synthesized via a simple low-temperature impregnation method at room temperature and atmospheric pressure as an effective electrochemical ammonia synthesis catalyst with high thermal stability. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), nitrogen adsorption–desorption apparatus, thermogravimetry (TG), and other characterization methods were applied to analyze the micro-morphology and physicochemical structure of the electrocatalyst. The synthesized ammonia performance of the catalyst was measured using an ultraviolet (UV) spectrophotometer and electrochemical workstation. The catalyst design used the doping of sulfur atoms to create rich catalytic active sites, while the presence of elemental sulfur on the catalyst surface provided hydrophobicity, which was conducive to inhibiting competitive hydrogen evolution reaction (HER) and enhancing the electrocatalytic ammonia synthesis performance of the catalyst. Under normal temperature and pressure conditions, when a voltage of −0.45 V was applied, the ammonia yield in 0.05 M H₂SO₄ electrolyte was 10.39 μg_NH3 mg_cat.⁻¹ h⁻¹. The results showed that the introduction of sulfur effectively improved the electrocatalytic and thermal safety performance of bio-derived carbon materials, and the test presented that the performance of the catalyst was stable and reusable. Full article