Exploring the molecular binding mechanism of 6-fluoro, 4-hydroxy, 2- methyl quinoline with TiO2 nanoparticles: A spectroscopic, thermodynamic, and insights into the solvatochromic effect.

This study investigates the interaction between titanium oxide nanoparticles (TiO2 NPs) and the heterocyclic fluorophore 6-fluoro,4-hydroxy,2-methylquinoline (6-FHMQ), aiming to understand fluorescence quenching mechanisms and thermodynamic characteristics. Spectroscopic techniques including spectrofluorometry (FL) and spectrophotometry (UV-Vis) were used, with a lifetime decay (τ) of 0.18 ns for 6-FHMQ measured using time correlated single photon counting (TCSPC). The interaction between 6-FHMQ and TiO2 NPs revealed a mix of static and dynamic fluorescence quenching mechanisms, with increasing quenching constants (Ksv) and a higher bimolecular quenching rate constant (Kq). The dynamic nature was highlighted by a temperature-dependent increase in binding sites from 1 to ~ 2. Spontaneous complexation was affirmed by negative change in free energy (ΔG), with negative change in enthalpy (ΔH) and a positive change in entropy (ΔS) values indicating favorable electrostatic and ionic interactions. The impact of varying TiO2 NP concentrations on 6-FHMQ absorption was analyzed using the Benesi-Hildbrand equation, with a quantum yield of 0.61 determined. By forster resonance energy transfer (FRET) theory, the proximity between 6-FHMQ and TiO2 NPs was found to be less than 70 Å. Ground and excited state dipole moments of 6-FHMQ in different solvents were calculated to demonstrate solvent sensing ability and charge transfer properties. Ultimately, this study serves as a testament to the power of scientific innovation in the realms of drug delivery and tissue engineering.

A novel and simple method for measuring nano/microplastic concentrations in soil using UV-Vis spectroscopy with optimal wavelength selection.

A simple method for measuring the concentration of nano/microplastics (N/MPs) in soil, which is difficult owing to the size of the filter mesh and the resolution of the measuring instrument, was investigated. A spectrophotometer was used for the measurements and polystyrene particles were used as the N/MP samples. When measuring N/MP concentrations in soil suspensions, absorbance was measured at two wavelengths, and the best combination of wavelengths for measurement was extracted because soil particles and leached components interfere with N/MP absorbance. A wavelength combination of 220-260 nm and 280-340 nm was found to be suitable for a variety of soils. As N/MPs are adsorbed on the surface of soil particles and precipitate with soil particles in suspension, a calibration curve was created between the concentration of N/MPs in the soil suspension and the N/MP content in the soil. The calibration curve showed a linear relationship, allowing for the estimation of the concentration of N/MPs in the soil. Although other N/MP materials, such as polyethylene and polyethylene terephthalate, must also still be considered and tested, this simple method has the potential to measure N/MPs in various types of soil.

Analysis of shade-matching ability in dental students: a comparative study under clinical and correcting light conditions.

BACKGROUND: Selecting the ideal tooth shade is essential to the success of aesthetic dental restorations. Students' cognitive abilities are involved in the multifaceted and intricate process of shade matching. Hence, the present study aimed to assess and compare the shade-matching ability of undergraduate dental students in various years of dental education under clinical and correcting light. METHODS: This comparative cross-sectional study was instigated amongst male 4th, 5th, and 6th-year students of the dental complex of King Faisal University, Kingdom of Saudi Arabia. A total of 72 male dental students assessed the shade under clinical (fluorescent light) and correcting light (handheld Dental Base Light) by using VITA Classical shade guides. Statistical analysis was done using SPSS version 23 (Armonk, NY, USA). The Chi-square test was used to evaluate the association between correct and incorrect shade matching under correcting and clinical light. RESULTS: Out of 72 male students, 22(30.6%) were from the 4th year, 26(36.1%) were from the 5th year, and 24(33.3%) were from the 6th year, with a mean age of 22.92 ± 1.01 years. The majority of the 6th-year students selected shade of anterior tooth # 11 correctly under clinical and correcting light, and 3(12.5%) students selected incorrectly under clinical and correcting light, with a statistically significant association among them (p = 0.004). As far as the shade selection of the posterior tooth is concerned, a statistically significant difference was observed under clinical light among all clinical students (p = 0.008). CONCLUSION: The clinical performance of dental students in shade matching improved with advancing years of dental education. Additionally, the shade matching ability of all groups of dental students was superior under correcting light compared to conditions under clinical light.

Explaining the colour of natural healthy gingiva.

To examine the differences between natural gingival colour in men and women. To determine the degree of predictability of changes in the gingival colour coordinates recorded for healthy gingiva, according to age, long-term medication, frequency of toothbrushing, and smoking habits. The CIELAB colour coordinates were recorded using a spectrophotometer for 360 Caucasian adult participants (aged 18-92 years), in three zones of the healthy attached gingiva of the maxillary central incisor. Regression models were created for each zone and each sex, taking the L*, a* and b* coordinates as dependent variables and age, frequency of toothbrushing, smoking habits (0-non-smoker; 1-smoker) and whether participants were taking long-term medication (0-no; 1-yes) as independent variables. The statistical analysis was conducted with SPSS version 26.0, using multiple regression models. Statistically significant differences between men and women were found only for colour coordinate b*, in all three zones. The only colour coordinate on which the predictor variables had a significant effect was the L* coordinate. In men, age and long-term medication had the greatest effect as predictors (maximum R2 = 0.149). In women, frequency of toothbrushing was the strongest predictor in the predictive models (maximum R2 = 0.099). The colour of gingiva in men contained a larger amount of blue, given that significantly lower values for colour coordinate b* were recorded in men than women, although this difference lacked clinical implications. For both sexes, the regression models produced had a modest predictive capacity. The L* coordinate was the dependent variable that showed the greatest predictability.

Evaluation of tooth color change after a bleaching process with different lasers.

The aim of this in vitro study was to evaluate the efficiency of diode laser-activated bleaching systems for color change of teeth. 75 extracted teeth were studied in five different bleaching protocols. Group 1: diode laser 445 nm, 320 µm fiber, 0.5W, continuous wave mode, dose 53 J/cm2. Group 2: diode laser 970 nm, 320 µm fiber, 1W, continuous wave mode, dose 106.10 J/cm2. Group 3: diode laser 940 nm, bleaching handpiece, 7W, continuous wave mode, dose 105 J/cm2. Group 4: diode laser 940 nm, 300 µm fiber, 2W, continuous wave mode, dose 47.16 J/cm2. Group 5: bleaching process without laser activation. In groups 1, 2 and 5, teeth were bleached with Perfect Bleach Office + and in groups 3 and 4, LaserWhite20 bleaching gel was used. Tooth color was determined immediately after the bleaching process using a spectrophotometer. Color change data on the CIE L * a * b* system was analyzed statistically by the one-way ANOVA and Tukey's HSD test. All bleaching procedures resulted in a change of color. All laser groups (∆E * ab > 3) have statistically larger ∆E * ab values than the control group (∆E * ab = 0.73) (p < 0.05). The diode laser 445 nm has the largest ∆E * ab value (∆E * ab = 4.65) and results in a significantly higher color difference than all other groups. In terms of color score difference in VITA Shades, all laser-activated groups lead to a lightening effect while the control group leads to only a slight lightening effect. The diode laser 445 nm produced the greatest color difference. Laser-activated bleaching is more effective than conventional bleaching without light activation. The diode laser 445 nm performs best in this in vitro study.

In-vivo repeatability of three intra-oral spectrophotometers.

OBJECTIVE: The objective was to assess the repeatability of three spectrophotometers, based on the CIELCh factors and shadeguide reference measurements. MATERIALS AND METHODS: Color analysis was performed using three devices: Rayplicker, Easyshade 4, and Easyshade V. Five repeated measures were performed by the same operator, on the right central maxillary incisor of 30 patients. The CIELCh factors were retrieved and the intra-class correlation was calculated. The Vita Classical and Vita 3D Master shadeguides were used to evaluate the respective Fleiss' Kappa factors. RESULTS: Rayplicker and Easyshade V demonstrated strong intra-class correlation based on the CIELCh factors: 0.98, 0.99, and 0.91 for Rayplicker, and 0.95, 0.99, and 0.93 for Easyshade V, for the L*, C*, and h* parameters, respectively. Regarding the repeatability of the shadeguide data, while Easyshade 4 had the best repeatability when using the Vita Classical as a reference, Rayplicker and Easyshade V showed better repeatability when using the Vita 3D Master. CONCLUSION: These findings suggest that both Rayplicker and Easyshade V are reliable devices for measuring CIELCh parameters. In terms of shadeguide references, the reliability of spectrophotometers is generally lower compared to the CIELCh measurements. CLINICAL SIGNIFICANCE: Given their good repeatability, both the Rayplicker and the Easyshade V spectrophotometers are reliable tools for prosthetic dental practices.

Feasibility assessment of a low-cost visible spectroscopy-based prototype for monitoring polyphenol extraction in fermenting musts.

BACKGROUND: Polyphenols have long been used to evaluate grape and wine quality and it is necessary to measure them throughout various winemaking stages. They are currently assessed predominantly through analytical methods, which are characterized by time-consuming procedures and environmentally harmful practices. Non-destructive spectroscopy-based devices offer an alternative but they tend to be costly and not readily accessible for smaller wineries. This study introduces the initial steps in employing a portable, user-friendly, and cost-effective visible (VIS) spectrophotometer prototype for direct polyphenol measurement during winemaking. RESULTS: Grapes (cv Syrah, Bobal, and Cabernet Sauvignon) at different maturation stages were fermented with or without stems. Throughout fermentation, parameters such as color intensity, total polyphenol index, total anthocyanins, and tannins were monitored. Concurrently, VIS spectra were acquired using both the prototype and a commercial instrument. Chemometric approaches were then applied to establish correlation models between spectra and destructive analyses. The prototype models demonstrated an acceptable level of confidence for only a few parameters, indicating their lack of complete reliability at this stage. CONCLUSIONS: Visible spectroscopy is already utilized for polyphenol analysis in winemaking but the aspiration to automate the process in wineries, particularly with low-cost devices, remains unrealized. This study investigates the feasibility of a low-cost and user-friendly spectrophotometer. The results indicate that, in the early stages of prototype utilization, the goal is attainable but requires further development and in-depth assessments. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The optical behavior of nano filled resin composite loaded with graphene oxide nanoparticles.

OBJECTIVES: Assessment of the effect of incorporation of graphene oxide nanoparticles (GONPs), different concentrations into resin composite with different thicknesses on its color modulation. MATERIALS AND METHODS: GONPs were prepared using the chemical reduction method and characterized using a transmission electron microscope and X-ray diffraction. The minimum concentrations of GONPs that provided the most effective antibacterial action (0.05 wt% and 0.2 wt%.) were prepared to be the concentration added to the tested resin composite. Calculations were done to find the required volume of the GONPs solution needed according to the mass of the resin composite. 70 nano-filled resin composite discs were prepared with 10 mm diameter × 3 mm height. 10 resin composite discs were prepared without GONPs incorporation and served as a control (G0). The other 60 resin composite specimens were divided into 2 equal groups (G1& G2) according to the concentration of the loaded nanoparticles in the specimens. Each group was divided into 3 equal subgroups according to the thickness of the resin composite containing GONPs; [T1: GONPs dispersed in the bottom 1 mm of the disc, while the top 2 mm of the disc was of resin composite only. T2: GONPs dispersed only in the bottom 2 mm of the disc and T3: GONPs dispersed in the total thickness of the disc (3 mm)]. ∆E values were calculated using a Vita Easy shade Spectrophotometer. RESULTS: Incorporation of GONPs into resin composite induced significant color change and among all the 6 experimental groups, G1T1 group (of 0.05 wt% concentration GONPs dispersed only in the bottom 1 mm of the disc) showed a non-significant color change. CONCLUSION: Dispersion of GONPs has a detectable effect on the color change of resin composite. Meanwhile, dispersion in low concentration for only the bottom 1 mm thickness of resin composite has an undetectable effect on its color.

Quantitative examination of factors influencing the colour reproduction ability of lithium disilicate glass-ceramics.

BACKGROUND: Effects of ceramic translucency, layer thickness, and substrate colour on the shade of lithium disilicate glass-ceramic restorations proved to be significant in several studies, however, quantitative, numerical results on the relationship between the colour difference and these parameters are still lacking. The purpose of this in vitro study was to quantitatively determine how the colour reproduction ability of a lithium disilicate glass-ceramic is affected by its translucency, layer thickness, and substrate colour. METHODS: Ceramic samples were prepared from A2 shade IPS e.max CAD blocks with high and low translucencies (HT and LT) in a thickness range of 0.5-2.5 mm (+/- 0.05 mm). Layered samples were acquired utilizing composite substrates in 9 shades; transparent try-in paste was used. The spectral reflectance of the specimens was assessed under D65 standard illumination with a Konica Minolta CM-3720d spectrophotometer. The CIEDE2000 colour difference (ΔE00) between two samples was analysed using perceptibility and acceptability thresholds set at 50:50%. Statistical analysis involved linear regression analysis and the Kruskal-Wallis test. RESULTS: An increase in the thickness of 0.5 mm reduced the ΔE00 of the HT samples to 72.8%, and that of the T samples to 71.1% (p < 0.0001). 7 substrates with HT and LT specimens had significantly different results from the mean (p < 0.05). A thickness of 0.5 mm is not sufficient to achieve an acceptable result at any level of translucency, while the low translucency ceramic at a thickness of 1.5 mm gave acceptable results, except for severely discoloured substrates (ND8 and ND9). CONCLUSIONS: The colour reproduction ability of lithium disilicate glass-ceramics is significantly affected by their translucency, layer thickness, and 7 substrates out of 9 substrates examined.

Color Change of Laminate Veneer Restorations Applied to Bleached Teeth.

OBJECTIVE: The aim of this study was to examine the color stability of laminate veneer restorations restored with CAD/CAM material applied to bleached teeth. MATERIAL AND METHODS: In this study, 80 upper central teeth extracted because of periodontal, orthodontic or trauma problems were used. The teeth were embedded in acrylic blocks and divided into 8 groups (n=10). Groups A, B, C and D were bleached with vital bleaching agent before preparation, and teeth were prepared for laminate veneer restorations. Groups E, F, G and H were prepared without bleaching. Groups A and E were restored with A1 GC LiSi Initial HT blocks, Groups B and F were restored with A1 GC LiSi Initial LT blocks, Groups C and G were restored with A1 IPS Emax CAD HT blocks, Groups D and H were restored with A1 IPS Emax CAD LT blocks. All restorations were adhesively cemented and aged for 2 and 5 years with thermal cycle. Color measurements of the restorations at the beginning, after 2 and 5 years of aging were measured with a spectrophotometer. RESULTS: All bleached groups had more color changes than the unbleached groups. The least color change after 2 years of aging was observed in GC LiSi Initial LT (ΔE00=0.81) and IPS Emax CAD LT (ΔE00=0.81) materials which were used on unbleached teeth and the most color change was observed in GC Initial LiSi HT (ΔE00=0.93) and IPS Emax CAD HT material (ΔE00=0.92) which were used on bleached teeth. After 5 years of aging, the least color change was observed in IPS Emax CAD LT (ΔE00=0.83) and GC LiSi Initial LT material (ΔE00=0.84) which were used on unbleached and the highest color change was observed in GC Initial LiSi HT (ΔE00=0.96) and IPS Emax CAD HT material (ΔE00=0.94) which were used on bleached teeth. CONCLUSION: Bleaching and translucency affect the color stability. No difference was detected between the color changes of GC LiSi Initial and IPS Emax CAD materials. The increase in aging time increased the color changes of all materials. CLINICAL SIGNIFICANCE: Bleaching and laminate veneer restorations may be preferred in many patients. For this reason, the long-term color change of laminate veneer restorations applied to bleached teeth is clinically very important. This study aimed to evaluate the effect of tooth bleaching on the long-term color change of laminate veneer restorations produced with different translucent CAD/CAM materials.

Evaluation of different color measurement methods for determining tooth color.

AIM: The purpose of this study is to develop software at a low cost that enables the detection of tooth colors by capturing photographs using various devices, and to compare its effectiveness with existing expensive methods. MATERIAL AND METHODS: A total of 60 anterior central incisor teeth from 30 individuals were included in the study. The CIELAB values (L,a,b) of each tooth were measured using a spectrophotometer, which is considered the gold standard. Subsequently, photographs of the teeth were taken using four different smartphones (iPhone- Xiaomi) and one digital camera (Canon). These images were then subjected to image processing techniques and compared with measurements obtained through computer-based analysis in order to assess the correlation. Data with three or more groups, the Kruskal-Wallis H test was utilized, and multiple comparisons were conducted using the Dunn test. A significance level of p<0.05 was considered. RESULTS: Upon examining the results of multiple comparisons, a statistically significant difference was observed (p<0.001) between the DeltaE values obtained from the camera of the iPhone and those obtained from the Canon DSLR and Xiaomi cameras. The iPhone cameras yielded result values ranging from 2.68 to 2.90 for DeltaE. CONCLUSIONS: It is reported that color determination methods based on image processing of photographs taken with iPhone mobile phones could potentially gain an advantageous position in routine clinical practice, as compared to spectrophotometry.

Developing of an eco-friendly liquid-liquid microextraction method by using menthol-based hydrophobic deep eutectic solvent for determination of basic fuchsin dye: assessment of the greenness profile.

Herein, we aimed to develop a new environmentally friendly liquid-liquid microextraction (LLME) method based on hydrophobic deep eutectic solvent (hDES) synthesized using biodegradable dl-menthol and decanoic acid for the spectrophotometric determination of toxic basic fuchsin dye in environmental water samples. The parameters affecting the extraction efficiency such as pH, mole ratio, and volume of hDES (1:2) and type and volume of organic solvent, sample volume, times of vortex, ultrasonic bath and centrifuge, ionic strength, and matrix effect were investigated and optimized. Under optimal conditions, the calibration curve showed linearity in the range of 7.4-167 µg L-1 with a coefficient of determination of 0.9994. The limit of detection, intra-day and inter-day precision, and recovery values were 2.25 µg L-1, 2.46% and 4.45%, and 105 ± 3%, respectively. The preconcentration and enrichment factors were found to be 30 and 61.5, respectively. The proposed hDES-LLME methodology was successfully applied to the environmental water samples to detect toxic BF dye (95-105%). Finally, the ecological impact of the suggested method was evaluated using the analytical eco-scale (PPS:88), complementary green analytical procedure indexe (ComplexGAPI), and the Analytical GREEnness tool (0.63). The assessment results showed that the presented analytical method can be regarded as a green LLME approach for the determination of the BF in water.

Shade match comparison of CAD-CAM single crowns to a lithium disilicate crown.

PURPOSE: To assess the shade match ability of four varieties of all-ceramic crowns to a neighboring bilayered lithium disilicate crown. MATERIAL AND METHODS: A dentiform was used to fabricate a bilayered lithium disilicate crown on the maxillary right central incisor, following the anatomy and shade of a selected natural tooth. Two crowns (one full-contour, one cutback) were then designed on a prepared maxillary left central incisor, following the contour of the neighboring crown. The designed crowns were used to manufacture monolithic lithium disilicate, bilayered lithium disilicate, bilayered zirconia, and monolithic zirconia crowns, 10 each. An intraoral scanner and a spectrophotometer were used to assess the frequency of matched shades and to calculate the color difference (ΔE) between the two central incisors at the incisal, middle, and cervical thirds. Kruskal-Wallis and two-way ANOVA were used to compare the frequency of matched shades and ΔE values, respectively (α = 0.05). RESULTS: There was no significant (p > 0.05) difference in frequencies of matched shades for each group at the three sites; except bilayered lithium disilicate crowns. Bilayered lithium disilicate crowns had significantly (p < 0.05) higher match frequency than monolithic zirconia at the middle third. The ΔE value was not significantly (p > 0.05) different among the groups at the cervical third. However, monolithic zirconia had significantly (p < 0.05) higher ΔE values than bilayered lithium disilicate and zirconia at the incisal and middle thirds. CONCLUSIONS: Bilayered lithium disilicate and zirconia appeared to most closely match the shade of an existing bilayered lithium disilicate crown.

Repeatability of different mobile phone applications for color measurement in dentistry.

PURPOSE: To assess the repeatability of various color-measuring mobile phone applications (MPAs) on dental materials in clinically relevant shades in 1-mm thickness. MATERIALS AND METHODS: A benchtop spectrophotometer was used as a reference instrument. Seven MPAs were used: Color Analysis, Color Analyzer-Iro Shirabe, Color Grab, and Colorimeter from Android, and Color Analyzer-Iro Shirabe, ColorMeter RGB, and Optishade from iOS. Color measurements were performed on 1-mm thickness slices of CAD-CAM materials, Vita Enamic shades 1M2, 2M2, 3M2, 4M2, and Vitablocs Mark II shades A1C, A2C, A3C, A4C (n = 10, for a total 80 specimens). The specimens were measured at three time periods, Day 0, Day 1, and Day 7, and three measurements were made on each day, to mimic short-, medium-, and long-term repeatability. The color differences were analyzed using the CIEDE2000 formula, with the corresponding color difference (ΔE00), and mean color difference from the mean (MCDM00). One-way ANOVA, Repeated measures ANOVA, and Paired sample t-tests were used for statistical analysis. RESULTS: Optishade from iOS showed the lowest mean color difference among the MPAs (ΔE00 = 0.2 (SD 0.1), 0.3 (SD 0.2), and 0.2 (SD 0.1) at Day 0, 1, and 7, respectively, and ΔE00 = 0.5 (SD 0.3) for all three periods Days 0-1, 0-7, and 1-7). Material-dependent variations in the repeatability of color measurements were observed. CONCLUSION: There was a statistically significant difference among color measurements using MPAs and a spectrophotometer, among the MPAs, and materials. The spectrophotometer exhibited the highest repeatability across the tested time periods. The iOS Optishade showed the highest repeatability among the MPAs.

Effect of Common Staining Beverages on Color Stability of Polymer-infiltrated Ceramics and Extra Translucent Zirconia: An In Vitro Study.

AIM: The current study aims to assess the color change of polymer-infiltrated ceramic Vita Enamic (VE) and extra translucent multilayer zirconia (XTML) after being immersed in different types of beverages, which are coffee, tea, and cola in comparison to distilled water as control. MATERIALS AND METHODS: A total of 80 rectangular-shaped specimens were prepared with fixed dimensions (14 × 12 × 0.5 mm) and then were divided into two groups (n = 40) according to ceramic material (VE, XTML). Specimens were sliced as each slice measures about 0.5 mm thick. Each group specimens were divided into four subgroups (n = 10) based on the immersion solutions in which specimens were stored (water, coffee, tea, and cola) for 28 days. The color parameters (L-a-b) of the specimens were recorded before immersion and at the end of the 7th (T1), 14th (T2), 21st (T3) and 28th (T4) days after immersion. Color measurements were statistically analyzed with a significance threshold of p < 0.05. RESULTS: There was a significant difference in color change between VE and XTML in all periods of tea and coffee immersion subgroups and in T3 and T4 in cola immersion subgroups (p < 0.001). Vita Enamic showed the highest differences in ΔE through all storage periods after 28 days of tea immersion (ΔE of VE= 8.06 ± 1.04). Extra translucent multilayer zirconia showed the highest differences in ΔE through all storage periods after 28 days of tea immersion (ΔE of XTML = 3.0 ± 0.33). CONCLUSION: Commonly consumed staining beverages influenced the color stability of the polymer-infiltrated ceramics more than extra translucent zirconia ceramics. CLINICAL SIGNIFICANCE: This study may provide guidance for clinicians to select the appropriate ceramic restorative material with high color stability and low tendency for color change by common staining beverages to achieve long-lasting esthetic results for the patients. How to cite this article: Abdelhafez MHA, Abu-Eittah MRH. Effect of Common Staining Beverages on Color Stability of Polymer-infiltrated Ceramics and Extra Translucent Zirconia: An In Vitro Study. J Contemp Dent Pract 2024;25(5):411-416.

Assessing the shade matching accuracy among dental students through visual and instrumental methods.

Objectives: To evaluate the shade selection accuracy of male dental students according to the three dimensions of color: value, hue, and chroma, using visual and instrumental shade selection methods under different lighting conditions. Methods: This comparative cross-sectional study was instigated amongst 70 male 4th, 5th, and 6th years BDS students of the Dental Clinics Complex at King Faisal University, Saudi Arabia for a duration of two months. First, the principal investigator determined the shade of tooth 11 and 46 on patient utilizing the spectrophotometer after calibration. In the next step, students were asked to select the shade of same tooth 11 and 46 using VITA 3D-Master shade guide under clinic lightening condition and corrected light. The characteristics of the color such as hue, chroma and value were recorded. The Kruskal-Wallis test was applied to find the significant difference in shade selection between visual and instrumental methods with respect to academic years. Results: The mean of the value of instrumental shade selection of tooth # 46 was slightly higher among 4th year students (4.41±0.73), than that of 5th year (3.72±1.02), and 6th year students (3.83±0.83), with a statistically significant difference among them (p= 0.024), indicating 6th year students selected darker shades. Additionally, a statistically significant relationship was noticed among 4th, 5th, and 6th year students with respect to the means of the chroma of 2.18 ±1.29, 2.92±1.11, and 3.13±1.10, respectively (p= 0.025). Conclusion: The selection of posterior teeth shades was notably influenced by academic years, employing both instrumental and visual methods, while considering color parameters.

Estimating intra-seasonal photosynthetic discrimination and water use efficiency using δ13C of leaf sucrose in Scots pine.

Sucrose has a unique role in recording environmental and physiological signals during photosynthesis in its carbon isotope composition (δ13C) and transport of the signal to tree rings. Yet, instead of sucrose, total organic matter (TOM) or water-soluble carbohydrates (WSC) are typically analysed in studies that follow δ13C signals within trees. To study how the choice of organic material may bias the interpretation of δ13C records, we used mature field-grown Scots pine (Pinus sylvestris) to compare for the first time δ13C of different leaf carbon pools with δ13C of assimilates estimated by a chamber-Picarro system (δ13CA_Picarro), and a photosynthetic discrimination model (δ13CA_model). Compared with sucrose, the other tested carbon pools, such as TOM and WSC, poorly recorded the seasonal trends or absolute values of δ13CA_Picarro and δ13CA_model. Consequently, in comparison with the other carbon pools, sucrose δ13C was superior for reconstructing changes in intrinsic water use efficiency (iWUE), agreeing in both absolute values and intra-seasonal variations with iWUE estimated from gas exchange. Thus, deriving iWUE and environmental signals from δ13C of bulk organic matter can lead to misinterpretation. Our findings underscore the advantage of using sucrose δ13C to understand plant physiological responses in depth.

Enhanced exopolysaccharide production by multi metal tolerant Klebsiella variicolaSMHMZ46 isolated from mines area and application in metal bioremediation.

The current study aimed to enhance exopolysaccharide production by Klebsiella variicolaSMHMZ46 isolated from the Zawar mines area in Udaipur, Rajasthan, India, by optimizing the medium with OFAT and a central composite design. The trial including sucrose (9.5%), casein hydrolysate (3%), and NaCl (0.5%) yielded the maximum EPS production as indicated by applying the CCD-RSM biostatistical program. The composition of exopolysaccharides produced by Klebsiella variicolaSMHMZ46 culture was characterized. Growth under Pb(II), Cd(II), and Ni(II) metal amended conditions induced EPS production relative to control. TLC was used for identifying the sugar residues of EPS, in addition to determination of both total carbohydrate and protein contents. According to FT-IR analysis, EPS can interact with metal ions via their functional chemical groups, thereby supporting their bioremediation potential. The metal removal efficiency of bacteria and their produced EPS in broth individually spiked with Pb(II), Ni(II), and Cd(II) was 99.18%, 97.60%, and 98.20%, respectively, and powdered EPS from contaminated water was 85.76%, 72.40%, and 71.53%, respectively. According to FEG-SEM observations, the surface morphology of EPS becomes rough, demonstrating sharp bumps after metal binding. A FEG-SEM analysis of the structure of EPS was performed; the surface structure of EPS (with metal) was more rigid than that of control EPS (without metal). The interaction between the EPS system and Pb(II) ions was investigated using FEG-SEM coupled with energy dispersive X-ray spectra, and a strong peak of C, O, and Pb elements was observed, indicating successful Pb adsorption. These findings suggest that EPS from Klebsiella variicolaSMHMZ46 has a good metal adsorbing nature and could be a promising biosorbent for metal bioremediation of contaminated water.

Environmental impact of endocrine-disrupting chemicals and heavy metals in biological samples of petrochemical industry workers with perspective management.

Exposure to endocrine disrupting chemicals (EDCs) or heavy metals are synthetic compounds that can lead to negative effect on health, including immune and endocrine system disruption, respiratory problems, metabolic issues, diabetes, obesity, cardiovascular problems, growth impairment, neurological and learning disabilities, and cancer. Petrochemical industry drilling wastes, which contain varying levels of EDCs, are known to pose a significant risk to human health. This study aimed to investigate the levels of toxic elements in biological samples of individuals working in the petrochemical drilling sites. Biological samples, including scalp hair and whole blood, were collected from petrochemical drilling workers, individuals residing in the same residential area, and control age-matched persons from nonindustrial areas. The samples were oxidized by an acid mixture before analysis using atomic absorption spectrophotometry. The accuracy and validity of the methodology were verified through certified reference materials from scalp hair and whole blood. The results showed that the concentrations of toxic elements, such as cadmium and lead, were higher in biological samples of petrochemical drilling employees, while lower essential element levels (iron and zinc) were detected in their samples. This study highlights the significance of adopting better practices to reduce exposure to harmful substances and protect the health of petrochemical drilling workers and the environment. It also suggests that perspective management including policymakers and industry leaders should take measures to minimize exposure to EDCs and heavy metals to promote worker safety and public health. These measures could include the implementation of strict regulations and better occupational health practices to reduce toxic exposure and promote a safer work environment.

Comparison of methods for determining Batrachochytrium dendrobatidis zoospore viability.

The emerging fungal pathogen Batrachochytrium dendrobatidis (Bd) threatens hundreds of amphibian species globally. During laboratory-based experiments it is often essential to quantify live Bd cells, but a comparison of the effectiveness of methods for counting and assessing the viability of the infectious zoospore life stage has not been done. A direct comparison of staining methods that assess viability will ensure that the most accurate and efficient method is used. Here, we compared the use of 2 relatively cheap common stains, trypan blue and methylene blue, and assessed their accuracy and precision for estimating the viability of Bd zoospores during both manual counting and colorimetric assays. We stained known proportions of killed Bd zoospores (0, 0.25, 0.50, 0.75, and 1.00) with each stain and estimated the proportion of stained (dead) and unstained (viable) cells in each sample using both manual counting and colorimetric assays. Trypan blue was found to be a much more effective stain than methylene blue for both microscopy and colorimetric assays. Additionally, counting zoospores via microscopy was both a more accurate and precise technique. We recommend using manual counts via microscopy using the trypan blue stain for assessing Bd zoospore viability.