Search

Background: To predict the long-term performance of restorative materials in the oral environment, it is important to evaluate their resistance to chemical and mechanical degradation and to know the toxic potential of the type and amount of ions eluted from the filling material. In this study, home bleaching was applied to dental materials with different contents and it was aimed to determine the type and amount of ions released from these materials. Methods: In this study, amalgam, posterior composite resin, anterior composite resin, bulk fill composite resin, indirect composite resin, hybrid ceramic and all-ceramic were used as restorative materials. 10 specimens of each material were prepared according to the manufacturer's instructions. Each material group was divided into two subgroups as the bleached group and the control group. After bleaching, all specimens were stored in 1 ml of 75% ethanol/water solution. Solutions were renewed after 1, 14 and 28 days. The type and amount of ions released from the materials were determined using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Data were analyzed using the Friedman, Wilcoxon Signed Ranks, and Mann-Whitney U tests (α = 0.05). Results: It was determined that the amount of ions release from the restorative materials decreased over time (p < 0.05). According to the results of the Mann-Whitney U test, there was no difference between the bleaching and control groups in most of the restorative materials (p > 0.05). Conclusion: Within the limits of this study, home bleaching system does not have a significant effect on ion release from restorative materials. [ABSTRACT FROM AUTHOR]

Objectives: This study was aimed to obtain an experimental bleaching agent by adding casein phosphopeptide‐amorphous calcium phosphate (CPP‐ACP) in order to eliminate the mineral loss on the tooth surface after bleaching and to evaluate the bleaching effectiveness. Materials and Methods: In this study, experimental bleaching agents containing 1%, 3% CPP‐ACP and without CPP‐ACP were obtained. Bleaching effectiveness (color change), the effect of bleaching agents on mineral content (energy dispersive x‐ray spectroscopy), surface morphology (scanning electron microscope), and surface hardness of enamel (Vicker's microhardness) before and after bleaching were evaluated. The obtained data were statistically analyzed. Results: When the bleaching levels of the groups were compared, no statistically significant difference was observed between the control and 1% CPP‐ACP groups (p > 0.05) while the addition of 3% CPP‐ACP decreased significantly the effectiveness of the bleaching agent (p < 0.05). When the effects of experimental bleaching agents on surface hardness were examined, while the enamel surface hardness decreased statistically significantly after application in the control group (p < 0.05), no statistically significant change was observed in surface hardness after the application of 1% CPP‐ACP containing bleaching agent (p > 0.05). However, a statistically significant increase was observed in surface hardness after the application of 3% CPP‐ACP containing bleaching agent (p < 0.05). When the Ca and P ratio of the groups were compared, no statistically significant difference was observed between the control and 1% CPP‐ACP groups (p > 0.05), while they increased significantly in 3% CPP‐ACP group (p < 0.05). Conclusions: The addition of 1% CPP‐ACP to the bleaching agent had positive effects on the mineral content and surface hardness of the enamel, and did not negatively affect the whitening effectiveness. Clinical Significance: Adding CPP‐ACP to the bleaching agent at appropriate concentrations can eliminate possible negative effects without compromising the effectiveness of the bleaching agent. [ABSTRACT FROM AUTHOR]

A corpus study of 100+ years of usage of the verb GRAB in American English contributes to the understanding of the way bleaching takes place. The meaning of GRAB as 'take or seize suddenly or eagerly' is firmly established in usage from 1910 through 1980, but in the 1990's many instances of a bleached sense of 'take or get easily or casually' begin to occur. The proposed hypothesis that bleaching results from hyperbolic uses is supported by the finding that bleaching occurs within three common contexts: narrative sequences of GRAB followed by another verb; contexts expanding on grab a bite (to eat); and GRAB plus human object, which changes from a sense of 'take custody of' to simply 'capture the attention of'. In addition, the interactional context of requests and offers (often of food and drink) hastens the bleaching of GRAB while also contributing the resulting interpretation of GRAB as 'get or take easily or casually'. The same conversational actions constitute the contexts in which GRAB is established in the ditransitive construction, as well as the contexts in which it takes on the social meaning of getting or taking in a quick, easy and casual manner. [ABSTRACT FROM AUTHOR]

This study investigates the physical, mechanical, and structural characteristics of handmade paper samples derived from cellulose extracted from grass clippings using two distinct methods as follows: (1) alkali treatment and (2) alkali treatment followed by bleaching, coupled with the incorporation of barium sulfate as a mineral filler. Our investigation revealed that the handmade paper samples' densities, moisture contents, and thicknesses varied within the ranges of 0.436 to 0.549 g/cm3, 5.60 to 2.51%, and 0.41 to 0.50 mm, respectively. The tensile strength and folding endurance of the papers produced through alkali treatment with barium sulfate were notably superior to those produced from bleached pulp and barium sulfate. Our analysis indicates that several critical factors, including paper density, thickness, the crystallinity index, and the microfibrillar structure of cellulose, intricately influence the mechanical and strength properties of the samples. Using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) techniques, we identified characteristic cellulose bonds and examined cellulose's crystalline and amorphous phases. Additionally, the crystallinity index of the samples was determined using both the Segal and peak deconvolution methods. Scanning electron microscopy (SEM) micrographs revealed interconnected networks of cellulose fibers with varying thicknesses and lengths, along with incorporated mineral filler within the cellulose fiber structure. Variations in mineral particle retention were attributed to the presence or absence of cellulose microfibrils. These findings contribute to our understanding of the observed strength characteristics of the paper samples and underscore the potential applications of cellulose derived from grass clippings, especially when combined with barium sulfate as a mineral filler in paper production. [ABSTRACT FROM AUTHOR]

Coral reefs worldwide are under increasing levels of pressure due to global and local stressors. Long-term monitoring of coral reefs through repeated observations at fixed survey sites allows scientists to assess temporal patterns in coral-reef communities and plays important roles in informing managers of the state of the ecosystems. Here, we describe coral assemblages in Papahānaumokuākea, the largest contiguous fully protected marine conservation area in the United States, using long-term monitoring data collected from 20 permanent (fixed) sites at three islands/atolls, Lalo, Kapou and Manawai, between 2014 and 2021. Significant temporal shifts in coral colony composition were detected at some of the monitoring sites, which were attributed to the impact of a mass coral bleaching event in 2014 and Hurricane Walaka in 2018. In particular, the bleaching affected multiple sites at Kapou and one site at Manawai where coral assemblages shifted from the Montipora dilatata/flabellata/turgescens complex to M. capitata dominance; despite being the dominant species at multiple monitoring sites prior to the bleaching, the M. dilatata/flabellata/turgescens complex has not been recorded at any of our monitoring sites in recent years. Coral conditions, such as bleaching, predation, subacute tissue loss, Porites pigmentation response and trematodiasis, did not show differences in the occurrence among the three islands/atolls once the site and temporal variabilities, as well as environmental covariates for bleaching, were considered. Coral genera, however, exhibited different sensitivities to these conditions. These findings highlight the importance of continuing coral reef monitoring at the species level, covering a broad range of coral assemblage compositions and habitat types in Papahānaumokuākea. [ABSTRACT FROM AUTHOR]

Elevated temperatures cause mass coral bleaching, leading to reef degradation. The frequency of bleaching events is increasing, and severe bleaching events have been predicted to occur annually in the next few decades. However, the ability of corals to acclimate and adapt to these unprecedented stresses remains unknown. In this study, we investigated how three years of consecutive thermal stress affect the adult fragments of the coral Acropora tenuis. The fragments were exposed to temperature treatments of ~ 28 °C (control) and ~ 31 °C (heat stress) until they began to bleach. We measured the survival rate, maximum quantum yield of photosystem II (Fv/Fm) of the symbiotic algae, and algal density of the fragments. The survival rate of the fragments under thermal stress decreased over the three-year period, reaching 20% by the end. Additionally, we observed a decrease in Fv/Fm and a reduction in algal density in the stressed fragments compared to those in the control fragments during all three years of the thermal stress period. These findings collectively suggested that consecutive bleaching-level thermal stress increases the susceptibility of corals to heat. [ABSTRACT FROM AUTHOR]

Exposure to more frequent ocean warming events is driving the loss of coral reef cover as the window of recovery between episodes of bleaching reduces. Coral propagation via in situ nurseries and subsequent outplanting have increased worldwide to support replenishing coral cover on degraded reefs. However, challenges in identifying fast-growing and bleaching-resistant target corals have limited how informative we can be regarding the resilience of outplanted corals. Here, we employed short-term thermal stress assays using the Coral Bleaching Automated Stress System (CBASS) to assess the thermal threshold of a fast-growing coral pre- and post-propagation on in situ nursery frames. We show that year-long nursery-propagated corals exhibit a statistically significant reduction in thermal thresholds (i.e., ED50s) compared to their corresponding reef-based donor colonies based on dose–response modelling of dark acclimated photosynthetic efficiency. RNA-Seq was then used to assess the underlying drivers of this thermotolerance reduction, identifying that processes involved in metabolic and oxidative stress management were disrupted in nursery versus donor heat-treated corals. Whether trade-offs during potential growth-focused phases (post-fragmentation), nursery conditions, and/or a consecutively high summer heat-load drove the lower thermal capacity remains to be determined. However, nursery corals expressed genes associated with telomere maintenance, which are typically expressed in stress-sensitive fast-growing corals under seasonal environmental stress, suggesting consecutively high summer heat-loading contributed to the observed patterns. Our results highlight that thermal tolerance is (i) variable and (ii) subject to acclimation to varying degrees across colonies. Thus, a path forward for reef practitioners to improve propagation efforts may entail the initial screening of a larger reef population from which thermally superior colonies can be selected for propagation. [ABSTRACT FROM AUTHOR]

Objective Materials and Methods Results Conclusions Clinical Significance To evaluate the effect of polishing and bleaching on the recovery of lightness, color, whiteness, and relative translucency parameter (RTP) in CAD/CAM materials and changes in these properties when another staining in coffee was conducted after the treatments.Disks of Lava Ultimate (LU), Vita Enamic (VE), IPS Empress CAD (EMP), IPS e.max CAD (EMAX), and Vita Suprinity (VS) were (1) not treated (control), (2) polished with Proxyt or (3) Ceramisté, (4) bleached with Opalescence PF or (5) Whiteness HP Blue, and (6) air polished with Clinpro Prophy Powder. CIE L*a*b* color coordinates were registered at baseline (R0), after staining with coffee for 30 min daily for 36.5 days and treatment (R1), and after another staining (R2). Differences (R1–R0 and R2–R0) in lightness (ΔL00), color (ΔE00), RTP (ΔRTP00), and whiteness (ΔWID) were evaluated by mixed repeated measures ANOVA and 95% confidence intervals (α = 0.05) and interpreted in function of their respective 50:50% PT and AT thresholds. Topography was evaluated by scanning electron microscopy (SEM).In LU, Opalescence PF and Proxyt decreased ΔL00R1–R0$$ {\Delta L}_{00\left({R}_1\hbox{--} {R}_0\right)} $$, ΔE00R1–R0$$ {\Delta E}_{00\left({R}_1\hbox{--} {\mathrm{R}}_0\right)} $$, and ΔWIDR1–R0$$ {\Delta \mathrm{WI}}_{\mathrm{D}\left({R}_1\hbox{--} {R}_0\right)} $$ and showed lower ΔL00R2–R0$$ {\Delta L}_{00\left({R}_2\hbox{--} {R}_0\right)} $$, ΔE00R2–R0$$ {\Delta E}_{00\left({R}_2\hbox{--} {R}_0\right)} $$, and ΔWIDR2–R0$$ {\Delta \mathrm{WI}}_{\mathrm{D}\left({R}_2\hbox{--} {R}_0\right)} $$. In VE, all treatments decreased ΔL00R1–R0$$ {\Delta L}_{00\left({R}_1\hbox{--} {R}_0\right)} $$, ΔE00R1–R0$$ {\Delta E}_{00\left({R}_1\hbox{--} {R}_0\right)} $$, and ΔWIDR1–R0$$ {\Delta \mathrm{WI}}_{\mathrm{D}\left({R}_1\hbox{--} {R}_0\right)} $$, whereas ΔL00R2–R0$$ {\Delta L}_{00\left({R}_2\hbox{--} {R}_0\right)} $$, ΔE00R2–R0$$ {\Delta E}_{00\left({R}_2\hbox{--} {R}_0\right)} $$, and ΔWIDR2–R0$$ {\Delta \mathrm{WI}}_{\mathrm{D}\left({R}_2\hbox{--} {R}_0\right)} $$ were lower in Opalescence PF than in the control group. In both moments, ΔE00 and ΔWID in EMP (also ΔL00) and EMAX were higher in Opalescence PF than in the control group, from which the other treatments did not differ in R1–R0. In EMP, ΔE00R2–R0$$ {\Delta E}_{00\left({R}_2\hbox{--} {R}_0\right)} $$ in Whiteness HP Blue (also ΔL00R2–R0$$ {\Delta L}_{00\left({R}_2\hbox{--} {R}_0\right)} $$) and Proxyt were also higher in comparison to the control group and in VS, Ceramisté decreased ΔL00R1–R0$$ {\Delta L}_{00\left({R}_1\hbox{--} {R}_0\right)} $$, ΔE00R1–R0$$ {\Delta E}_{00\left({R}_1\hbox{--} {R}_0\right)} $$, and ΔRTP00R1–R0$$ \varDelta RT{P}_{00\left({R}_1\hbox{--} {R}_0\right)} $$, whereas Opalescence PF increased ΔRTP00R1–R0$$ {\Delta \mathrm{RTP}}_{00\left({R}_1\hbox{--} {R}_0\right)} $$. ΔE00R2–R0$$ {\Delta E}_{00\left({R}_2\hbox{--} {R}_0\right)} $$ of Ceramisté and ΔWIDR2–R0$$ {\Delta \mathrm{WI}}_{\mathrm{D}\left({R}_2\hbox{--} {R}_0\right)} $$ and ΔRTP00R2–R0$$ \varDelta RT{P}_{00\left({R}_2\hbox{--} {R}_0\right)} $$ of Proxyt were lower than those of the control group.The most suitable treatment to recover the lightness, color, whiteness, and RTP without changing these properties after another coffee exposure is material‐dependent.Although the effectiveness of the treatment was material‐dependent, Proxyt was the only treatment that promoted clinically acceptable changes for both LU and VE, while for purely ceramic materials, this condition was observed with Ceramisté and Clinpro Prophy Powder. [ABSTRACT FROM AUTHOR]

Almond shell (AS) represents about 33% of the almond fruit, being a cellulose-rich by-product. The use of greener methods for separating cellulose would contribute to better exploitation of this biomass. Subcritical water extraction (SWE) at 160 and 180 °C has been used as a previous treatment to purify cellulose of AS, followed by a bleaching step with hydrogen peroxide (8%) at pH 12. For comparison purposes, bleaching with sodium chlorite of the extraction residues was also studied. The highest extraction temperature promoted the removal of hemicellulose and the subsequent delignification during the bleaching step. After bleaching with hydrogen peroxide, the AS particles had a cellulose content of 71 and 78%, with crystallinity index of 50 and 62%, respectively, for those treated at 160 and 180 °C. The use of sodium chlorite as bleaching agent improved the cellulose purification and crystallinity index. Nevertheless, cellulose obtained by both bleaching treatments could be useful for different applications. Therefore, SWE represents a promising green technique to improve the bleaching sensitivity of lignocellulosic residues, such as AS, allowing for a great reduction in chemicals in the cellulose purification processes. [ABSTRACT FROM AUTHOR]

To obtain a more appealing wood coating with lighter color, bleaching treatment was employed. Bleached and unbleached bio-polyurethane (PU) coating was prepared using liquefied bamboo and was applied to rubberwood. The coated wood surface was examined for adhesion, scratch, abrasion, impact, and resistance to common household chemicals. The results revealed that the bleaching of liquefied bamboo exerted mixed effects on the finishing properties of the bio-PU coating. Specifically, the surface coated with unbleached bio-PU coating exhibited noticeably higher levels of scratch and impact resistance compared to the surface coated with bleached bio-PU coating. However, both the adhesion and abrasion properties were found to be similar in both cases. Both bleached and unbleached bio-PU coating exhibited similar resistance to various household chemicals, with exception of acetic acid. This research demonstrated a method for producing semi-transparent bio-PU from bamboo biomass for use in wood coating. Bleaching treatment is feasible to produce light-colored coating without significantly affecting the finishing properties of the bio-PU coating. [ABSTRACT FROM AUTHOR]

Copyright of Transactions of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Background To predict the long-term performance of restorative materials in the oral environment, it is important to evaluate their resistance to chemical and mechanical degradation and to know the toxic potential of the type and amount of ions eluted from the filling material. In this study, home bleaching was applied to dental materials with different contents and it was aimed to determine the type and amount of ions released from these materials. Methods In this study, amalgam, posterior composite resin, anterior composite resin, bulk fill composite resin, indirect composite resin, hybrid ceramic and all-ceramic were used as restorative materials. 10 specimens of each material were prepared according to the manufacturer’s instructions. Each material group was divided into two subgroups as the bleached group and the control group. After bleaching, all specimens were stored in 1 ml of 75% ethanol/water solution. Solutions were renewed after 1, 14 and 28 days. The type and amount of ions released from the materials were determined using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Data were analyzed using the Friedman, Wilcoxon Signed Ranks, and Mann-Whitney U tests (α = 0.05). Results It was determined that the amount of ions release from the restorative materials decreased over time (p 0.05). Conclusion Within the limits of this study, home bleaching system does not have a significant effect on ion release from restorative materials.

This research explored the isolation of cellulose from coconut shells using ultrasound. It involved two types of cellulose isolation: alkali and bleached cellulose (ABC) and ultrasound-alkali-assisted isolated cellulose (UAIC). The products were characterized using various techniques, including attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM). The ATR-FTIR results confirmed the effective removal of lignin and hemicellulose in the ABC and UAIC samples. Field emission scanning electron microscopy analysis revealed the production of micro-sized cellulose. The TGA and XRD results showed improved thermal stability and crystallinity in ABC and UAIC, attributed to the elimination of non-cellulosic constituents. However, the thermal stability and crystallinity of UAIC were lower compared to ABC, likely due to the cavitation effect caused by sonication. The findings suggest that ultrasonication is an efficient and promising method for isolating cellulose.

High sea surface temperatures recorded in summer 2021 introduced a unique opportunity for 'real-time' assessment of Exmouth Gulf turbid reef's resilience to a marine heatwave event. Four sites along a turbidity and temperature gradient were surveyed during (March 2021) and after (October 2021) the event to assess bleaching rates (Bleaching Index = BI), differences in coral morphological responses to the heat wave, and post-event changes in benthic and coral community structure. Despite experiencing higher temperatures (> 30 °C) and Degree Heating Weeks (DHW = 8), the most turbid reef site, Somerville, displayed greater resilience to heat stress (BI = 14) compared to the "clear water" site, Bundegi (BI = 19.3), where temperatures never exceeded 30 °C (3 DHW). Our results also reveal that encrusting and massive corals, often considered more resilient to bleaching, displayed increased bleaching susceptibility at the turbid sites, potentially due to the synergistic effects of sedimentation and heat stress. In contrast, branching and foliose corals showed greater resilience to the heat wave in turbid water settings, while encrusting and branching corals exhibited lower resilience in the clearwater site. These findings highlight complex interactions between heat and reduced UV stress on turbid reefs potentially increasing resilience to bleaching but likely only for those coral morphologies that are not heavily impacted by sedimentation. [ABSTRACT FROM AUTHOR]

This study aimed to assess the effects of dental bleaching on the immediate shear bond strength (SBS) of composite to enamel. Different bleaching methods and time intervals between bleaching and composite restoration were examined. A total of 45 enamel specimens were divided into three groups (n = 15) based on the applied bleaching protocol: in‐office (A), at‐home (B), and unbleached control (C). Groups A and B were then subdivided into three time intervals until bonding: 1, 3, and 7 days. The composite was bonded to enamel using self‐etch adhesive technique and submitted to SBS testing. The enamel surface and adhesive interface were observed under scanning electron microscope (SEM). The highest average SBS was measured in the control (unbleached) group (31.1 ± 3.4). A significant difference in SBS was found between the control and in‐office bleaching (p <.001), as well as between control and at‐home bleaching (p =.034), while the difference between in‐office and at‐home bleaching methods was insignificant. In relation to the waiting period, a significant reduction in SBS (p <.001) was found 1 day post‐bleaching. The weakest marginal sealing to enamel under SEM was observed also 1 day after bleaching. Both bleaching methods significantly reduced the SBS of composite to enamel, especially immediately after the bleaching procedure. Reduction in SBS is temporary and 3‐day waiting period seems to be sufficient to reverse the adverse effects of bleaching. Research Highlights: SBS of composite to enamel is significantly reduced by bleaching procedures, especially immediately after bleaching.The reduction in SBS is temporary and reversible by delaying the restoration for a minimum of 3 days. [ABSTRACT FROM AUTHOR]

Abstract Background To investigate the effect of a 50% ascorbic acid with 50% citric acid solution on the immediate shear bond strength (SBS) of metallic brackets after tooth bleaching. The enamel etching pattern and the required quantity of these combined acids as antioxidants following 35% hydrogen peroxide (HP) bleaching were also determined. Methods The stability of the solution at room temperature was assessed at various time intervals. Fifty teeth were randomly divided into five groups: non-bleached (G1), bleached then acid etched (G2), bleached followed by a 10-minute treatment with 10% sodium ascorbate and acid etched (G3), 5-minute treatment with 50% ascorbic acid (G4), and 5-minute treatment with a combination of 50% ascorbic acid and 50% citric acid (G5). Groups G2, G3, G4 and G5 were bleached by 35% HP gel for a total of 32 min. Acid etching in groups G1, G2, and G3 was performed using 37% phosphoric acid (Ormco®, Orange, CA, USA) for 15 s. In all groups, metal brackets were immediately bonded using Transbond™ XT primer and Transbond™ PLUS adhesive, with light curing for 40 s. The SBS was tested with a universal testing machine, and statistical analysis was conducted using one-way ANOVA followed by Tukey’s HSD test. The level of significance was set at p 0.05). SEM analysis revealed enamel etching patterns similar to those of both control groups (G1 and G2). Kinetic studies at 6 min indicated that the antioxidation in G5 reacted 0.2 mmole lower than in G3 and G4. Conclusion 5-minute application of the combined acids enhanced the SBS of bleached teeth comparable to unbleached teeth. The combined acids remain stable over two weeks, presenting a time-efficient, single-step solution for antioxidant application and enamel etching in orthodontic bracket bonding.

To obtain a more appealing wood coating with lighter color, bleaching treatment was employed. Bleached and unbleached bio-polyurethane (PU) coating was prepared using liquefied bamboo and was applied to rubberwood. The coated wood surface was examined for adhesion, scratch, abrasion, impact, and resistance to common household chemicals. The results revealed that the bleaching of liquefied bamboo exerted mixed effects on the finishing properties of the bio-PU coating. Specifically, the surface coated with unbleached bio-PU coating exhibited noticeably higher levels of scratch and impact resistance compared to the surface coated with bleached bio-PU coating. However, both the adhesion and abrasion properties were found to be similar in both cases. Both bleached and unbleached bio-PU coating exhibited similar resistance to various household chemicals, with exception of acetic acid. This research demonstrated a method for producing semi-transparent bio-PU from bamboo biomass for use in wood coating. Bleaching treatment is feasible to produce light-colored coating without significantly affecting the finishing properties of the bio-PU coating.

Background: Aim of this study is to assess the color matching in class III restorations made with single-shade resin composite after bleaching with different carbamide peroxide concentrations. Methods: In this study, 20 human incisors that were free of caries or enamel abnormalities and freshly extracted for periodontal or orthodontic reasons were cleaned of blood, debris, and calculus. Mesial and distal surfaces were restored with single-shade composite (Omnichroma, Tokuyama, Japan). All samples were randomly divided into two groups, all of the mesial surfaces were isolated, and distal surfaces were coated with %10 and %15 carbamide peroxide (Opalescence PF; Ultradent Products, Inc, USA). Polishing discs (Zenit Flex, President Dental, Germany) were used the composite restoration. Color matching was evaluated on photographs with a digital colorimeter. SPSS software program was used to perform statistical analysis (IBM Corp., Armonk, NY, USA). Results: Statistically significant difference was found between the color matching of the restorations after the 5th treatment with 15% carbamide peroxide (p = 0.004), and at the end of 10th treatment with 10% carbamide peroxide (p = 0.028). Depending on the carbamide peroxide concentration, after the 5th treatment a statistically significant difference was found between 15% and 10% carbamide peroxide (p = 0.000), but no statistically significant difference after the 10th treatment (p > 0.05). Conclusions: After carbamide peroxide bleaching, hard tissue color became lighter. Since there is no color pigment in single-shade composites, color might be lighter after bleaching. Therefore, these composites may be considered safer in bleaching. Keywords: Bleaching, Color Match, Composite

Cellulose-based impact polypropylene copolymers (IPC) has been developed by utilizing Arenga pinnata “ijuk” fiber. The cellulose from pristine ijuk fiber (IF) was extracted via alkalization and bleaching treatment using NaClO, with KMnO4 as the activator. The purpose of using KMNO4 is to replace the use of acid buffers in every process that uses NaClO. The fibers’ properties, namely their compound content, morphology, crystallinity index, and crystallite size, were characterized and investigated to examine the treatment effect. The Fourier-transform infrared (FTIR) spectroscopy shows that the majority of lignin and hemicellulose were removed throughout the treatment process. FTIR semi-quantitative analysis, based on absorbance ratio, reveals that IFB5, the fiber treated with 5% NaClO for 5 h, exhibits the highest cellulose content. The scanning electron microscopy (SEM) was performed to observe the fibers’ morphology. The X-ray diffraction (XRD) characterization reveals that IFB5 contains cellulose Iβ type and exhibits the highest crystallinity index, 62.27%. The fiber was then utilized to develop a cellulose-based IPC composite. The IPC Ijuk Treatment (IPC Ijuk T) shows a good bonding characteristic between fiber and the matrix, the highest crystallinity percentage, 67,18%, the lowest melting point, 162.8 °C, and the highest thermal stability, started to degrade at 265 °C and decomposed at 447 °C. Thus, IPC Ijuk T can be considered applicable as IPC composite filler.

Background Purpose Methods Results Conclusions Optically stimulated luminescent dosimeters (OSLDs) can be bleached and reused, but questions remain about the effects of repeated bleaching and fractionation schedules on OSLD performance.The aim of this study was to investigate how light sources with different wavelengths and different fractionation schemes affect the performance of reused OSLDs.OSLDs (N = 240) were irradiated on a cobalt‐60 beam in different step sizes until they reached an accumulated dose of 50 Gy. Between irradiations they were bleached using light sources of different wavelengths: the Imaging and Radiation Oncology Core (IROC) bleaching system (our control); monochromatic red, green, yellow, and blue lights; and a polychromatic white light. Sensitivity and linearity‐based correction factors were determined as a function of dose step‐size. The rate of signal removal from different light sources was characterized by sampling these OSLDs at various time points during their bleaching process. Relative doses were calculated according to the American Association of Physicists in Medicine Task Group‐191. Signal repopulation was investigated by irradiating OSLDs (N = 300) to various delivered doses of 2, 10, 20, 30, 40, and 50 Gy in a single fraction, bleached with one of the colors, and read over time. Fractionation effects were evaluated by irradiating OSLDs up to 30 Gy in different size steps. After reading, the OSLDs were bleached following IROC protocol. OSLDs (N = 40) received irradiations in 5, 10, 15, 30 Gy fractions until they had an accumulated dose of 30 Gy; The sensitivity response of these OSLDs was compared with reference OSLDs that had no accumulated dose.Light sources with polychromatic spectrums (IROC and white) bleached OSLDs faster than did sources with monochromatic spectra. Polychromatic light sources (white light and IROC system) provided the greatest dose stability for OSLDs that had larger amounts of accumulated dose. Signal repopulation was related to the choice of bleaching light source, timing of bleaching, and amount of accumulated dose. Changes to relative dosimetry were more pronounced in OSLDs that received larger fractions. At 5‐Gy fractions and above, all OSLDs had heightened sensitivity, with OSLDs exposed to 30‐Gy fractions being 6.4% more sensitive than reference dosimeters.The choice of bleaching light plays a role in how fast an OSLD is bleached and how much accumulated dose an OSLD can be exposed to while maintaining stable signal sensitivity. We have expanded upon investigations into signal repopulation to show that bleaching light plays a role in the migration of deep traps to dosimetric traps after bleaching. Our research concludes that the bleaching light source and fractionation need to be considered when reusing OSLD. [ABSTRACT FROM AUTHOR]

Introduction: Hydrogen peroxide for bleaching procedure, can penetrate the interprismatic space of enamel and dentin tubules, leading to pulp irritation. Oxidative stress resulting from this irritation triggers an inflammatory reaction in the pulp, increasing the number of macrophage cells. One approach to mitigate the cytotoxic effects of bleaching agents diffusing is the application of antioxidants. Green tea contains numerous catechins known for their antioxidant activity. This study aims to investigate the impact of applying green tea extract gel (Camellia sinensis) at concentrations of 5% and 10% on macrophage cell count in the tooth pulp of Wistar rats' after an extra coronal bleaching procedure using 40% hydrogen peroxide. Materials and methods: Fifteen upper molars from Wistar rats' divided into three groups. The control group underwent the bleaching procedure alone. The teeth were rinsed in the control group with warm distilled water, while the first group received 5% and second group received 10% green tea extract gel. On the 5th day, molar specimens were collected and prepared for histological examination using hematoxylin-eosin (HE) staining. Macrophage cell counts were calculated using a light microscope at 400x magnification. Results: The Results of one-way ANOVA test revealed a significant influence of green tea extract concentration on macrophage cell count (p < 0.05). LSD post hoc test indicated significant differences in all compared groups. Conclusion: Application of 10% green tea extract concentration resulted in a lower macrophage cell count compared to both the 5% concentration and the control group. [ABSTRACT FROM AUTHOR]

Introduction: Hydrogen peroxide, a bleaching agent for teeth, can reach and damage pulp tissue by diffusion through enamel and dentine structures. Pulp inflammation, in the form of reactive oxygen species (ROS), causes discontinuity of the odontoblast layer. Antioxidants are common ROS suppressants, one of which is polyphenols found in green tea (Camelia sinensis). The aim this in vivo study was to determine the effect of 5% and 10% green tea extract gel concentration in odontoblast cells of the Wistar rats' teeth after extracoronal bleaching with 40% hydrogen peroxide. Materials and methods: Fifteen molar teeth of male Wistar rats were applied with a bleaching agent on the occlusal surface. The teeth in the control group were rinsed with warm distilled water after bleaching. In the experimental groups, the teeth were applied with 5% and 10% green tea extract gel after bleaching. Wistar rats were sacrificed on the fifth day after treatment, followed by hematoxylin-eosin staining. Histological examinations were observed under light microscope using 400x magnification, followed by determination of discontinuity scoring. Results: The results of Kruskal-Wallis test showed a significant effect of the green tea extract gel concentration for the odontoblast layer discontinuity in all groups (p < 0.05). Mann-Whitney test result showed significant difference in all compared pair groups (p < 0.05). Conclusion: The application of 10% green tea extract gel shows the lowest discontinuity score compared to the 5% extract gel application and the control group. [ABSTRACT FROM AUTHOR]

Single tooth orange discoloration secondary to root canal calcification occurs as a consequence of dental trauma, orthodontic treatment, or for unknown rea-sons. A correct case history must be compiled and a CBCT study carried out in order to establish the diag-nosis and define the best treatment plan in each case. The aim of the present study was to offer a therapeutic protocol involving a clinical decision-making tree dia-gram based on the presence or absence of apical dis-ease and the degree of canal calcification. Dental bleaching and the use of ceramic veneers allow es-thetic restoration in such cases. (Int J Esthet Dent 2024;19:170-185) [ABSTRACT FROM AUTHOR]

In this study, decolorization via a bleaching operation was carried out on chrome and dye spotted skins with several bleaches to valorize the defective leather materials. Sodium perborate, hydrogen peroxide, sodium thiosulfate, sodium percarbonate, and oxalic acid were applied as bleaching agents in production. Sodium perborate by itself was applied and combined with other bleaching agents. Combined processes were also supported with an emulsifier agent for uniform distribution and deeper penetration of bleaching agents into the fibers. Color changes and differences on leather products were determined by Konica Minolta CM-3600d test apparatus spectrophotometrically before and after the applications. Bleached leathers were processed again, re-dyed, and finished after the bleaching operations. Then, bleaching performances of the single and combination applications were also evaluated for the leather strength indicators by analyzing tensile and tear strength of the final products as well as chromium (VI) oxidation of basic chromium (III) salts used in tanning. Antibacterial properties of the final bleached products were also investigated. As a result, sodium perborate was found to provide the most effective and safe bleaching without any physical and chemical deformation by creating antibacterial activity on leather. [ABSTRACT FROM AUTHOR]

The goal of this study is to present an environmentally benign route for cotton fabric and investigate the effect of different pretreatments in natural dyeing. In this context, conventional alkaline scouring, conventional hydrogen peroxide bleaching, low-temperature one-step biopreparation processes, namely enzymatic scouring (alkaline pectinase and alkaline pectinase-neutral cellulase combination) at 55 °C and enzyme-bleaching agent (hydrogen peroxide/sodium percarbonate/sodium perborate)-activator agent (TAED) combinations at 65 °C were applied to 100% cotton knitted fabric. The use of agricultural waste and eco-friendly mordants was preferred in natural dyeing. For this purpose, pretreated fabrics were dyed with the outer green shell of almond fruit extracts and a low amount of 0.4 g/L metal mordants (alum and iron(II) sulfate) in accordance with the simultaneous mordanting method. The dyeing properties of bio- and conventionally prepared cotton fabrics were examined in terms of colorimetric data (K/S, CIELa*b*C*h°) and wash fastness compared with water absorbency, whiteness, weight loss, pectin removal, and type of mordant. Excellent wash fastness values were achieved regardless of the type of pretreatment. Low-temperature one-step biopreparation can be a good substitute for conventional scouring and bleaching processes. Since different results can be achieved, it is essential to determine and evaluate all bioprocess conditions depending on the end-use characteristics of the textile (e.g. whether it will be white or dyed/printed, its color and lightness/darkness) at the laboratory and industrial scale applications. [ABSTRACT FROM AUTHOR]

Heat stress-induced bleaching has been shown to lower the photosynthetic and physiological performances and even causes mortality in giant clams. However, there is a lack of information on the responses of sub-tropical giant clams to bleaching stress as well as their recovery from bleaching. Here we exposed the giant clams Tridacna crocea from sub-tropical Okinawa to different temperature conditions for 21 days and then examined their recovery at control temperatures (28–29 °C) within 42 days. T. crocea in control and in 30–31 °C retained their colors, whereas bleaching was observed in 32–33 °C and in the increasing temperatures (29–33 °C, 1 °C change every 5 days). The Fv/Fm decreased at 32–33 °C and in the increasing temperatures (29–33 °C), even before the onset of bleaching, but the Fv/Fm returned to baseline values at day 9 of recovery period. Zooxanthellae density and chlorophyll a + c concentrations were decreased, whereas the zooxanthellae cell size was increased in all elevated temperatures at day 21 of exposure period. Respiration (R) in all temperature conditions was not affected during exposure period, whereas gross photosynthesis (Pg) and Pg/R were reduced at 32–33 °C. At day 42 of recovery period, most bleached individuals regained their colors, phototrophic potential, and zooxanthellae population. No giant clams died within 21 days of exposure period, but mortalities were observed at 32–33 °C and at increasing temperatures (29–33 °C) during recovery period. This study shows that the sub-tropical giant clams are vulnerable to heat stress, but their ability to recover may suggest their persistence in a warming ocean. [ABSTRACT FROM AUTHOR]

Melanin, particularly eumelanin, is commonly viewed as an efficient antioxidant and photoprotective pigment. Nonetheless, the ability of melanin to photogenerate reactive oxygen species and sensitize the formation of cyclobutane pyrimidine dimers may contribute to melanin‐dependent phototoxicity. The phototoxic potential of melanin depends on a variety of factors, including molecular composition, redox state, and degree of aggregation. Using complementary spectroscopic and analytical methods we analyzed the physicochemical properties of Dopa‐melanin, a synthetic model of eumelanin, subjected to oxidative degradation induced by aerobic photolysis or exposure to 0.1 M hydrogen peroxide. Both modes of oxidative degradation were accompanied by dose‐dependent bleaching of melanin and irreversible modifications of its paramagnetic, ion‐ and electron‐exchange and antioxidant properties. Bleached melanin exhibited enhanced efficiency to photogenerate singlet oxygen in both UVA and short‐wavelength visible light. Although chemical changes of melanin subunits, including a relative increase of DHICA content and disruption of melanin polymer induced by oxidative degradation were considered, these two mechanisms may not be sufficient for a satisfactory explanation of the elevated photosensitizing ability of the bleached eumelanin. This study points out possible adverse changes in the photoprotective and antioxidant properties of eumelanin that could occur in pigmented tissues after exposure to high doses of intense solar radiation. [ABSTRACT FROM AUTHOR]

Plant fibers have been studied as sources of nanocellulose due to their sustainable features. This study investigated the effects of acid hydrolysis parameters, reaction temperature, and acid concentration on nanocellulose yield from maguey (Agave cantala) fiber. Nanocellulose was produced from the fibers via the removal of non-cellulosic components through alkali treatment and bleaching, followed by strong acid hydrolysis for 45 min using sulfuric acid (H2SO4). The temperature during acid hydrolysis was 30, 40, 50, and 60 °C, and the H2SO4 concentration was 40, 50, and 60 wt. % H2SO4. Results showed that 53.56% of raw maguey fibers were isolated as cellulose, that is, 89.45% was α-cellulose. The highest nanocellulose yield of 81.58 ± 0.36% was achieved from acid hydrolysis at 50 °C using 50 wt. % H2SO4, producing nanocellulose measuring 8–75 nm in diameter and 72–866 nm in length, as confirmed via field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis. Fourier-transform infrared spectroscopy (FTIR) analysis indicated the chemical transformation of fibers throughout the nanocellulose production process. The zeta potential analysis showed that the nanocellulose had excellent colloidal stability with a highly negative surface charge of −37.3 mV. Meanwhile, X-ray diffraction (XRD) analysis validated the crystallinity of nanocellulose with a crystallinity index of 74.80%. Lastly, thermogravimetric analysis (TGA) demonstrated that the inflection point attributed to the cellulose degradation of the produced nanocellulose is 311.41 °C. [ABSTRACT FROM AUTHOR]

Cellulose-rich sugarcane trash (SCT) biomass, an important agricultural residue generated in large quantities every year, was used as a potential feedstock for cellulose extraction in micro and nano form. Initially, the cellulose microfibers were isolated from the SCT by a two-step chemical treatment process (alkali pretreatment with sodium hydroxide followed by hydrogen peroxide bleaching) at different operating parameters. The microfibers were then converted into the nanoscale by acid hydrolysis. The quantification of the raw and chemically treated SCT was carried out by the Van Soest method to learn their chemical composition. Different characterisation techniques such as Fourier Transform Infrared spectroscopy (FTIR), Thermogravimetric Analysis (TGA), X-Ray Diffraction (XRD), Field Emission-Scanning Electron Microscopy (FE-SEM), and Transmission Electron Microscopy (TEM) were used for the analysis of surface functional groups, thermal stability, crystallinity index, surface morphology, and the internal structure of the raw as well as chemically treated SCT biomass respectively. The quantification results show the optimum process conditions for the alkali pretreatment as 5% (w/v) alkali (NaOH) concentration, 60 °C, and 12 h process time and for bleaching as 20% H2O2 concentration, 80 °C, and 8 h process time. This produces material having 86.15% cellulose content. This indicates the effective removal of hemicellulose and lignin. For the acid hydrolysis reaction for converting cellulose microfibers into nanocrystalline cellulose, the concentration of H2SO4 required was 40 wt.%, which is comparatively lower than that reported in the literature (~ 65 wt.%). The characterisation results highlight the progressive enrichment in the cellulosic groups, thermal stability, and crystallinity of the material with respect to the processing stages. There was a progressive enhancement in the crystallinity index of the sample observed with respect to the chemical treatment, with a maximum of up to 84.83% for the hydrolysed material. The XRD and TEM analysis confirms the presence of nanocrystalline cellulose (NCC) in the final hydrolysed sample. [ABSTRACT FROM AUTHOR]

Objectives: This study investigated the presence of mercury in commonly used over the counter skin-lightening creams available in Trinidad and Tobago. The objective of this study was to evaluate if skin-lightening creams commonly used in Trinidad and Tobago contained Mercury, and establish the health risks presented by these products. Methods: Nineteen skin-lightening creams were analysed using Cold Capor Atomic Absorption Spectrophotometry (CV-AAS). Margin of Safety (MoS) and Hazard Quotient (HQ) calculations were used to assess risk to users. Results: Of the nineteen creams assessed, sixteen contained high concentrations of mercury (0.294-14414.5 μg/g), only three creams had no mercury detected. 9 of the 19 samples contained levels of mercury that exceed the Minamata convention's accepted limit of 1μg/g, with 3 samples exceeding 3800.000 μg/g. Risk assessments using MoS and HQ showed that 3 of the samples were unsafe for use and are considered hazardous. The study also revealed that many creams do contain mercury even if it did not constitute part of the product formulation. Conclusion: The data infers that some manufacturers do add mercury to their formulations while others are the victims of contaminated raw materials. MoS and HQ show that 21% of the samples were unsafe and 16% can be considered hazardous for human use. It is possible that with such levels of mercury in these products and the popularity of these products within the Caribbean Community and its diaspora, that there exists a significant amount of members with higher than acceptable mercury levels, with undiagnosed clinical symptoms. [ABSTRACT FROM AUTHOR]

Coral bleaching, the stress‐induced breakdown of coral‐algal symbiosis, threatens reefs globally. Paradoxically, despite adverse fitness effects, corals bleach annually, even outside of abnormal temperatures. This generally occurs shortly after the once‐per‐year mass coral spawning. Here, we propose a hypothesis linking annual coral bleaching and the transmission of symbionts to the next generation of coral hosts. We developed a dynamic model with two symbiont growth strategies, and found that high sexual recruitment and low adult coral survivorship and growth favour bleaching susceptibility, while the reverse promotes bleaching resilience. Otherwise, unexplained trends in the Indo‐Pacific align with our hypothesis, where reefs and coral taxa exhibiting higher recruitment are more bleaching susceptible. The results from our model caution against interpreting potential shifts towards more bleaching‐resistant symbionts as evidence of climate adaptation—we predict such a shift could also occur in declining systems experiencing low recruitment rates, a common scenario on today's reefs. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to compare the effect of office bleaching of teeth bonded with Transbond XTTM (3M Unitek, Monrovia, CA, USA) (TRXT) and the use of color change resistant Orthocem (FGM, Joinville, Brazil) in bracket bonding on coffee-induced enamel discoloration. Materials and methods: Eighty premolars were distributed in equal numbers (n = 20) to group 1 (TRXT + distilled water), group 2 (TRXT + coffee solution), group 3 (TRXT + coffee solution + bleaching), and group 4 (Orthocem + coffee solution). Color was measured using a SpectroShade Micro (MHT, International, Verona, Italy) device at the beginning (T0), after coloring (T1), after bleaching (T1B), and after debonding (T2). ΔE color change values were calculated as T1-T0, T1B-T0 and T2-T0 differences. The conformity of the data to the normal distribution was examined with the Shapiro–Wilk test. Multiple comparisons were made with Tamhane’s T2 test and Tukey’s HSD test using one-way analysis of variance in the comparison of normally distributed data, and multiple comparisons were made with Dunn’s test using the Kruskal–Wallis H test for comparison of non-normally distributed data. The significance level was set at p < 0.050. Results: A statistically significant (p < 0.001) difference was found between the T1-T0 and T2-T0 stages for group 1–4 ΔE values. A statistically significant (p < 0.001) difference was also found when the T1B-T0 ΔE values of group 3 were compared with the T1-T0 ΔE values of groups 1, 2, and 4. Conclusions: After coffee-induced enamel discoloration, bleaching of teeth bonded with TRXT produced acceptable color difference of the incisal, middle, and gingival regions of the crown. In teeth bonded with Orthocem, acceptable color difference was seen only in the middle of the crown. Clinical relevance: The presented study will guide the clinician on how enamel discoloration side effect of fixed orthodontic appliance can reduce. [ABSTRACT FROM AUTHOR]

Fish oil by-product (FOB) recovered from the precooking process in the cannery industry and the pressing process in fish meal production are potential resources. However, this fish oil still needs a refinery process to improve the quality of fish oil. This study aimed to identify the physicochemical characteristics of the initial fish oil by-product, the physicochemical profiles, and fatty acids of the fish oil by-product after degumming neutralization and bleaching (bentonite, zeolite, and carbon adsorbents) processes from the cannery and fish meal industry. Results showed the initial physicochemical characteristics of fish oil waste from fish flour have lower quality than canned products (acid value, free fatty acids, PV, AV, TOTOX value, viscosity, and refractive index) but are inversely proportional to the iodine value. Results showed degumming (D) and neutralization (N) processes from the Fish oil canning process (FCP) and Fish oil meal process (FMP) could improve the quality parameters of fish oil by-products by reducing the acid value (7.90, 0.65, 9.17, 0.58 mg KOH/g), respectively; free fatty acid (3.97, 0.33, 4.60, 0.29 % oleic) respectively; peroxide value (PV) (15.18, 7.38, 17.64, 7.10 mEq/kg), respectively; anisidine value (AV) (14.36, 6.61, 14.64, 6.51) respectively; total oxidation (TOTOX) value (44.72, 21.37, 49.64, 20.71) respectively; and iodine (167, 153, 163, 155 mg/100 g), respectively as well as increasing the lightness (23.80, 25.70, 20.65, 26.00), respectively. In the bleaching process (B), zeolite (15 %) was an effective adsorbent to obtain oil with the best quality parameters due to zeolite possessed greater polarity and surface area at a higher concentration, which resulted in the acid value for FCP and FMP (0.26, 0.22 mg KOH/g); free fatty acid (0.13, 0.15 % oleic); PV (2.44, 5.71 mEq/kg); AV (2.5, 4.9); TOTOX value (7.16, 9.11); and iodine (138, 151 mg/100 g) as well as increasing the lightness (37.08, 36.74) that are appropriate to International Fishmeal & Oil Manufacturers Association (IFOMA), Codex Alimentarius Committee (CAC), and International Fish Oils Standards (IFOS) standards (p < 0.05). All adsorbents effectively increase the brightness of the FOB. The higher the concentration of adsorbents, the higher the clarity of the FOB. For zeolite absorbents, there was an increase of 16.73 - 32.3 % for FCP and 15.39 - 32.69 % for FMP, but the viscosity decreased with a range of 24.50 - 36.50 cPs. FCP contains 14 fatty acids, while FMP contains 12 fatty acids. The number of SFA and MUFA detected in FCP is lower than in FMP. In contrast, the amount of PUFA in FCP is relatively higher than in FMP. The percentage of EPA and DHA in FCP is lower than in FMP. Overall, the refining process affects the fatty acid composition of fish oil by-products both in the canning process and in fish meal. [ABSTRACT FROM AUTHOR]

Hypochlorous acid bleaching under amine catalysis (Hcat bleaching stage) is an optimized bleaching stage variant that is characterized by working at weakly acidic, near-neutral pH, having high bleaching efficiency, and discharging only very small amounts of chloro-organics. This study addressed the chemical fate of the used 1,4-diazabicyclo[2.2.2]octane (DABCO) catalyst. While literature proposed either homolytic or heterolytic breakage of one ethylene bridge and subsequent release of the resulting fragments as two molecules of formaldehyde, we demonstrated the degradation to proceed by ionic elimination of one ethylene bridge starting from mono-N-chlorinated DABCO. The resulting N-vinyl (enamine) derivative adds water under the release of acetaldehyde and formation of piperazine. The generation of acetaldehyde was experimentally confirmed by 2,4-dinitrophenylhydrazine trapping, directly from the processing liquid. The experimental findings agreed superbly with computations which showed the "acetaldehyde mechanism" to be much favored over the previously proposed pathways under C–C bond cleavage and release of formaldehyde. The results of this study add to a better understanding of the novel Hcat bleaching system. [ABSTRACT FROM AUTHOR]

In the present study, cellulose was effectively separated from eucalyptus wood with ternary solvents containing organic base 1,1,3,3-tetramethyl guanidine and other organic solvents such as morpholine, N-ethyl morpholine, dimethyl formamide, glycerin, ethylene glycol and diethylene glycol. It was found that the combination of 1,1,3,3-tetramethyl guanidine with morpholine was favorable for achieving high delignification and less loss of cellulose. The removal of lignin and hemicellulose achieved 89.8% and 81.4% after heating for 6 h at 160 °C, respectively. It was found that the combination of 1,1,3,3-tetramethyl guanidine with morpholine was favorable for achieving high delignification and less loss of cellulose. The removal of lignin and hemicellulose achieved 89.8% and 81.4% after heating for 6 h at 160 °C, respectively. The addition of morpholine and water promoted the dissolution of lignin and reduced the degradation of cellulose. Subsequently, the crude cellulose was further purified through a simplified bleaching process, the final removal of lignin and hemicellulose increased to 98.7% and 97.5% respectively, and cellulose with a purity of 96.9% was achieved. The scanning electron microscopy analysis indicated that the diameter of cellulose bundles decreased from about 250 μm to about 20 μm after organic solvents treatment. The fiber bundle was completely separated into a single fiber with a diameter of about 5–10 μm after bleaching process. X-ray diffraction analysis revealed an increase in the crystallinity of fiber from 69.4% to 83.3%, implying a reduction of lignin and hemicellulose in eucalyptus. Fourier transform infrared spectra revealed the high selective removal of lignin and hemicellulose. Two-dimensional 1H-13C Heteronuclear singular quantum correlation was performed to investigated the structure units and linkages of lignin and found that only the structural signal of C5-H5 in guaiacyl (G5) alone existed in the aromatic region, while the signals -OCH3, Cγ–Hγ in β-O-4' (Aγ) and β-β' (Cγ) remained in the side chain region, indicating that lignin could be effectively degraded and dissolved by the ternary solvents. In conclusion, high purity cellulose was obtained from eucalyptus wood by environmentally friendly and recyclable processes. [ABSTRACT FROM AUTHOR]

Resin infiltration is an effective method to mask vestibular white spots. If needed, external bleaching is usually recommended before infiltration, whilst in clinical practice, this sequence may not always be feasible. This in vitro study evaluated the effect of bleaching after resin infiltration regarding surface roughness and color using bovine incisors. Unlike for the untreated specimens (control, n = 25), artificial caries lesions were created within the test group (n = 25) using a demineralization solution at 37 °C for five days (pH = 4.95). The lesions were subsequently infiltrated using a resin infiltrant (Icon, DMG, Hamburg, Germany), followed by polishing. Afterwards, all specimens were bleached with a 10% carbamide peroxide gel (Opalescence, Ultradent, South Jordan, UT, USA) for 8 h/day over a ten-day period. Between bleaching treatments, specimens were stored in an opaque container with moistened paper tissues at 37 °C. Surface roughness was measured using a profilometer, and color in the L*a*b* space was assessed spectrophotometrically before and after bleaching. Bleaching increased the L*-values of both infiltrated (mean ± SD; ΔL* = 3.52 ± 1.98) and untreated (control) specimens (ΔL* = 3.53 ± 2.30) without any significant difference between the groups (p = 0.983). Bleaching also induced a significant increase in the mean surface roughness of both infiltrated (p < 0.001) and untreated (p = 0.0134) teeth. In terms of clinical relevance; it can be concluded that bleaching resin-infiltrated enamel is as effective as bleaching sound enamel. [ABSTRACT FROM AUTHOR]

Objective: To investigate the symbiotic bacterial diversity of Hydra sinensis undergoing bleaching induced by strong light and high temperature. Method(s): The bleaching of H. sinensis was induced under strong light (6000 Lux, 25℃), high temperature (2000 Lux, 33℃) and combined stresses of strong light and high temperature (6000 Lux, 33℃), respectively. After 21 days of bleaching experiment, the bleaching degree of H. sinensis was detected by counting symbiotic algae in single cells of H. sinensis, and the diversity and abundance of symbiotic bacteria in H. sinensis were studied by use of high-throughput sequencing of 16S rDNA. Result(s): The number of symbiotic algae was observably decreased under strong light, high temperature and combined stresses of strong light and high temperature (P<0.05). The abundance of Phylum Cyanobacteria in H. sinensis increased under strong light, while the abundances of Phylum Cyanobacteria and Chlorobi in H. sinensis increased significantly under the combined stresses of strong light and high temperature. In addition, KEGG enrichment analysis indicated that symbiotic bacteria in H. sinensis undergoing bleaching were related to the biosynthesis and metabolism of antioxidants such as linoleic acid, carotenoid and betalain. Conclusion(s): Cyanobacteria and chloracea may provide their photosynthetic products to the host of H. sinensis to make up for the nutritional deficiency caused by the decrease of symbiotic algae. Furthermore, the diversity of symbiotic bacteria in H. sinensis changed in the direction of improving the antioxidant capacity of the host under strong light and/or high temperature stress. [ABSTRACT FROM AUTHOR]

The health of coral reefs is declining from the effects of human activity and climate change. Mass coral bleaching is often triggered by elevated water temperature and excessive solar irradiance. Shading can reduce coral bleaching risk. Shading-based management interventions, such as whole-ofreef marine fogging, have been proposed as a conservation tool for periods when coral undergoes excessive thermal stress. This study examined the effect of intermittent shade (30% for 0, 4, or 24 h) on two coral species, Duncanopsammia axifuga and Turbinaria reniformis, held at either 26.4°C or 32.4°C for 18 days. Coral fragments were assessed for bleaching (relative mean intensity of grey, chlorophyll a, and symbiont density), photochemistry (PAM fluorometry), and antioxidant biomarkers (SOD and CAT). Shading responses were species-specific, with T. reniformis more responsive to shading than D. axifuga. Thirty per cent shading delayed bleaching up to three-degree heat weeks (DHW), and 24 h shade was more protective than 4 h shade. Shading suppressed catalase activity in T. reniformis. Overall, our results suggest that intermittently shading corals for 4 h can moderate light stress and slow bleaching in some corals and could improve the efficiency of active solar radiation management in marine ecosystems. [ABSTRACT FROM AUTHOR]

Background and Aim: This research examines the effect of two antioxidants, pomegranate peel extract, and green tea, on the shear bond strength of microhybrid composite on bleached enamel using sixth-generation bonding. Materials and Methods: 44 premolar teeth were used in this study. The samples were divided into 4 groups, Group A: composite restoration without previous bleaching treatment. Group B: Restoration of teeth immediately after bleaching treatment. Group C: Bleaching treatment, then using 5% green tea extract as an antioxidant on the tooth surface, followed by tooth restoration. Group D: Bleaching treatment, then using 5% pomegranate peel extract as an antioxidant on the tooth surface, followed by tooth restoration. For the restoration, the 6th generation Bond SE (Kuraray Dental, Japan) and micro-hybrid composite (3M ESPE, USA) Filtek Z250 were used. To measure the strength of the shear band, the Zwick universal testing machine (Berlin, Germany) was used, and at the end, the types of failure were examined using a stereomicroscope. Calculations were done using PASS II and SPSS 25 software, OneWay ANOVA, Tukey, and homogeneity of variance tests. Results: No significant difference was observed between groups A, C, and D (P>0.99), but between these groups and group B, the amount of shear band strength was significantly different (P<0.001). Conclusion: The use of 5% pomegranate peel extract and green tea increases the shear bond strength of composite to bleached teeth. [ABSTRACT FROM AUTHOR]

Copyright of China Pulp & Paper is the property of China Pulp & Paper Magazines Publisher and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lignocellulose material is the main natural resource for the pulp and paper industry, and for its application the material should have a degree of whiteness as high as possible. For this reason, different bleaching treatments were applied during time. In this paper, the photobleaching induced by solar light of a lignocellulosic biomass using NaClO was studied. The colorimetric measurements, UV spectra absorption, and FTIR spectra changes are evaluated and discussed in this paper. The changes of L*a*b parameters can be considered a proof of the reactions generated by hypochlorite radicals during solar light exposure, leading to a biomass whitening. [ABSTRACT FROM AUTHOR]

In this study, the performance of waste seashells (SS) in adsorbing color and oxidation parameters during the bleaching process of sunflower oil was evaluated and compared with that of commercial clay. Seashell activation methods included microwave treatment (900 W for 30 min), acid treatment (7 N H2SO4), and a combination of both. Interestingly, the unactivated SS demonstrated superior adsorption performance compared with the activated SS. SS, which have the ability to eliminate color pigments like chlorophyll and carotenoid, were found to be effective in this regard. However, their effectiveness in reducing the peroxide and p-anisidine value was not as successful as that of commercial clay. Free acidity content remained constant across all treatments. SS emerged as a cost-effective alternative adsorbent, promising in preventing environmental pollution. Their use signifies a valuable contribution to sustainability. This study sheds light on SS potential as an eco-friendly solution in industrial processes, warranting further exploration and application. Practical applications Biowaste valorization is a process that involves converting organic waste materials into valuable products, energy, or resources, instead of simply disposing of them in landfills or incinerating them. This approach has gained significance owing to its potential to address environmental, economic, and social challenges. In this respect, this study presents that bioadsorbent obtained from waste SS can be utilized for bleaching of sunflower oil. [ABSTRACT FROM AUTHOR]

Background: Although bleaching is typically considered a safe procedure, various investigations have found minor negative effects and changes in mineral composition. The aim was to Evaluate and compare the efficacy of using Nanohydroxyapatite serum on surface microhardness of enamel surface before and after bleaching with chemically cured Boost bleaching. Material and methods: ten sound human permanent upper and lower premolar teeth were used and their roots were removed 2 mm apically to the cementoenamel junction, the crowns were sectioned mesiodistally into two halves buccal and lingual/palatal, the buccal surface was further subdivided into two halves. The samples were embeded in an acrylic resin, resulting in 30 specimens divided into 3 groups: Control group: using Boost bleaching and stored in artificial saliva for 14 days, prevention group: nanohydroxyaptite (n-HAP) serum applied 2-3 min once daily for 10 days followed by bleaching then stored for 14 days in artificial saliva and treatment group: in which bleaching used before nanohydroxyapatite serum and stored in artificial saliva for 14 days. The samples were subjected to a Vickers microhardness test measured at 4 times: base line, after nanohydroxyapatitem, after one day of bleaching and after storage in artificial saliva for 14 days in all groups. The data were analyzed statistically using repeated analysis of variance (ANOVA) test followed by Tukey's test. Results: there was a significant increase in microhardness in the prevention group (p 0.05). Conclusion: n-HAP may enhance the microhardness of a bleached enamel surface when used as a preventive & treatment measure. Suggested that a higher increase in enamel microhardness occurs when n-HAP is used for 2-3 min once daily for 10 days before bleaching and maintaining this increase even after storage for 14 days in artificial saliva.

IntroductionTraditionally, internal tooth bleaching was performed using sodium perborate slurries. These are banned in some areas for potential carcinogenic effects. More recently, highly concentrated hydrogen peroxide gels have been used, which may cause dentin degradation. Consequently, the search for ideal internal tooth bleaching agents is still on. This study compared pure ROS-releasing granules regarding their liberation of oxidizing species, pH induction, bleaching of blood-stained dentin, and effects on mechanical dentin properties.Materials and methodsThe ROS-releasing granules under investigation were sodium perborate, carbamide peroxide, and sodium percarbonate in aqueous suspension (4:3, wt/wt). The bleaching efficacy of these suspensions was compared in blood-stained human dentin (n = 6) ex vivo. In addition, effects on mechanical dentin integrity were tested using bovine dentin beams (n = 9) exposed to a 3-point bending test (ISO 4049) after immersion in test suspensions or control solutions (35% H2O2 and physiological saline) for 1 week.ResultsGranules release between 21.5% and 35.2% (wt/wt) of H2O2 equivalent. The sodium-containing granules (perborate and percarbonate) caused an alkaline pH of 10.3 and 10.6, respectively. The carbamide peroxide suspension was acidic (pH 3.9), as was the 35% H2O2 solution used as a control (pH 2.2). All the suspensions bleached the blood-stained dentin, albeit with a lesser overall effect by sodium percarbonate (one-way ANOVA and Tukey's HSD, p

Objective: This study evaluated the sealing ability of different biomaterials as intra-orifice barriers in the internal bleaching of discolored teeth with the walking bleaching technique. The release of hydroxyl ions from the bleaching materials can cause cervical root resorption, making it necessary to use intra-orifice barrier materials to prevent this issue. Materials and methods: In the current study, the high-performance liquid chromatography (HPLC) method was used to measure the released hydroxyl ions. The study included 90 single-rooted and single-canal premolars, which were divided into four groups based on the intra-orifice barrier materials used (mineral trioxide aggregate [MTA], calcium-enriched mixture [CEM], Biodentine, and MTA+PG) and the type of bleaching material (sodium perborate + water or sodium perborate + hydrogen peroxide 30%). Two control groups were also considered in this study: a positive control group, where sodium perborate and hydrogen peroxide were placed inside the pulp chamber without any intra-orifice barriers; and a negative control group, where no bleaching agent or surgical obstruction was used, and the root surface was covered with wax up to the cemento-enamel junction (CEJ) level. Results: The results showed that there was a significant difference in the concentration of hydroxyl ions released among the studied groups. The amount of hydroxyl ion released was highest in the positive control group and lowest in the CEM group. Among the intra-orifice barrier materials used, CEM cement was found to be the most appropriate material for use in the step-by-step internal bleaching method. Conclusions: The study highlights the importance of using appropriate intra-orifice barrier materials to prevent root cervical resorption in internal bleaching procedures.