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This study aimed to compare changes in oral health-related quality of life (OHRQoL) resulting from three vital tooth bleaching protocols. The participants (n = 105) were randomly assigned to one of three vital bleaching treatment groups: home bleaching (HB), in-office bleaching (IOB), or combined bleaching (CB). HB involved the use of custom-made trays and 10% carbamide peroxide for a 14-day treatment period. IOB utilized 37.5% hydrogen peroxide applied in three cycles. CB treatment involved the use of IOB followed by HB. Tooth colour change was evaluated using a shade guide (ΔVS) and a digital spectrophotometry device (ΔES). The Oral Health Impact Profile-14 (OHIP-14) and Oral Impact on Daily Performance-22 (OIDP-22) instruments were used to assess changes in OHRQoL at baseline, 15-days and 6-month recalls. Linear mixed models were used to estimate between- and within-group differences. All bleaching protocols led to significant improvements in overall OHIP-14 scores at the 6-month recall (p ≤ 0.037). CB and IOB treatments were associated with more substantial positive impacts on overall scores, psychological discomfort, physical disability (CB only), and psychological disability (CB only) compared to HB (p ≤ 0.011). Significant enhancements in OIDP-22 scores were observed in the CB and HB groups at the 6-month recall compared to baseline (p ≤ 0.006), with evidence indicating that these improvements were greater in the CB group compared to the IOB group (p = 0.007). All bleaching treatments demonstrated a positive impact on OHRQoL. However, the positive impact was most consistent across domains and age groups in the CB group. The positive impact was less pronounced in older age groups. [ABSTRACT FROM AUTHOR]

• Novel 3 min tooth whitening by means of reduction and liposome encapsulation. • The novel treatment presented enhanced penetration compared to carbamide peroxide. • Changes over the enamel mineral were observed and compared to carbamide peroxide. • MicroFTIR coupled to Synchrotron light was used to study the extent of its effects in bovine incisors. To compare the side effects of typical whitening treatments (by means of oxidation) compared to the new treatment developed by the authors through reduction. The aim is to provide information about the chemical interactions of the encapsulated reductant agent (metabisulfite, MBS) with the enamel structure compared with carbamide peroxide (CP) and to study their penetration in the hydroxyapatite (HAP) and the changes produced in the mineral and its hardness. Chemical imaging is performed by synchrotron-based micro Fourier transformed infrared spectroscopy (SR-µFTIR). Continuous Stiffness Measurements (CSM) were used to determine the depth reached by the treatments in order to delimitate the area of study. The SR-µFTIR studies showed that MBS treatments softened the first 10 µm of enamel, as happens in the initial stages of tooth decay. Principal component analysis (PCA) showed that the main differences between treatments were found in the intensity of the ν 3 PO 4 3- peak related to tooth demineralization. CP and MBS promoted different changes in the HAP mineral, observed as opposite shifts of the peak: CP shortened the P-O bond while MBS seemed to elongate it. Moreover, MBS promoted the loss of carbonates while CP did not, which is probably related to the solution's pH. When comparing MBS and MBS Liposomes, it was observed how liposomes favoured the diffusion of MBS to inner layers, since the effects of MBS were observed in deeper enamel. Thus, the encapsulated MBS whitening effect is highly improved in terms of time when compared to MBS alone or CP. The obtained results indicated that using oxidizing (CP) or reducing (MBS) treatments, promote different HAP mineral changes, and that liposomes favour the diffusion of MBS into the enamel. It is the first time that synchrotron light is used to map the bovine incisor's enamel chemically, and to determine the effect of a whitening treatment in terms of chemical HAP modifications, and the extent in deep of these effects. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyze and compare the efficacy of different bleaching agents typically used for internal bleaching of endodontically treated discolored teeth. Electronic databases (PubMed, Web of Science, and Cochrane Library) were searched by 2 reviewers for clinical trials in which the color of endodontically treated discolored teeth before and after internal bleaching was examined using shade guide units (ΔSGU) or a spectrophotometer/colorimeter (ΔE). The efficacies of the bleaching agents were compared using subgroup analyses. Statistical heterogeneity was assessed with the Cochran Q test and I 2 statistic. Publication bias was evaluated using funnel plots. Eight studies were included in the systematic review, 6 of which could be included in the meta-analyses. Internal bleaching led to a significant change in tooth shade (ΔSGU: 6.27 [95% confidence interval, 5.36–7.17], ΔE: 12.83 [95% confidence interval, 9.46–16.20]). With regard to ΔSGU, the use of carbamide peroxide (35% or 37%), hydrogen peroxide (35%), and the combination of sodium perborate and hydrogen peroxide (3% or 30%) led to a better bleaching effect than sodium perborate (adjusted P value ≤.026). Regarding ΔE, there were no significant differences between carbamide peroxide (37%), hydrogen peroxide (35%), and sodium perborate mixed with hydrogen peroxide (P =.051). The risk of bias of the included studies was classified as moderate to high. Carbamide peroxide, hydrogen peroxide, and sodium perborate have a significant bleaching effect on discolored, root canal–treated teeth. For a valid assessment of shade stability and a comparison of bleaching agents and their concentrations, further studies with long-term recalls are necessary. [ABSTRACT FROM AUTHOR]

Cytotoxicity caused by the reactive oxygen species (ROS), such as singlet oxygen species (1O 2), superoxide radical (O 2 -), and hydroxyl radical (HO), is a mechanism for treating cancer cells in radiation therapy. 5-aminolevulinic acid (5-ALA)-mediated radiodynamic therapy (RDT) is more effective in killing tumor cells than conventional radiation therapy. ROS is produced not only by ionizing radiation but also by Cherenkov light-activated protoporphyrin IX (PpIX), which is metabolized endogenously from 5-ALA. Moreover, PpIX also catalyzes hydrogen peroxide to generate 1O 2 , and an enhanced catalytic yield of 1O 2 was observed in X-ray irradiation in vitro. Therefore, using an in-vivo mouse model, this study aimed to investigate the effect of hydrogen peroxide as a coenzyme catalyst on a novel 45MV 5-ALA-mediated RDT. A subcutaneous C57BL/6 mouse model of KP1 cell line was used. The tumors (n = 240) were randomized into six groups, consisting of untreated, conventional radiation treatment (RT), and RDT with or without hydrogen peroxide: 1. control (untreated), 2. hydrogen peroxide, 3. 45MV RT, 4. 45MV RT + hydrogen peroxide, 5. 45MV RDT, 6. 45MV RDT + hydrogen peroxide. For 45MV photon irradiation, a single fraction of 4 Gy was delivered to the tumors. 5-ALA was systemically injected at 100 mg/kg by tail-vein 4 hours before the treatment for endogenous PpIX accumulation in the tumor. Carbamide peroxide was used to deliver hydrogen peroxide to tissue and was administered at 60 mg/kg intratumorally into tumors ∼3-5 min before the treatment. The treatment effect of a single fraction of treatment was measured by calculating tumor growth, measured using a 1.5 T MR scanner on the day of treatment (prior to the treatment), 3 and 7 days post-treatment. Two-way repeated ANOVA with Bonferroni correction was used to compare each treatment group to determine the statistically significant difference in tumor growth. A total of 45MV RDT with hydrogen peroxide was shown to significantly delay the tumor growth for the mouse model and cell line investigated in this work. 45MV RDT with hydrogen peroxide group resulted in a decrease in tumor growth by 51.3 ± 4.1 % and 56.1 ± 5.1 % compared to the control group on 3 and 7 days post-treatment, respectively (P<0.001), and 43.4 ± 0.8 % and 50.9 ± 0.8 % compared to 45MV RT alone on 3 and 7 days post-treatment, respectively. Moreover, the enhancement effect of hydrogen peroxide on 45MV RDT was 2.2-4.7 times greater on 45MV RT alone (P<0.05). Hydrogen peroxide did not contribute to tumor growth when administered alone. A total of 45MV 5-ALA-mediated RDT with hydrogen peroxide resulted in the most significant tumor growth delay compared to the other groups. The catalytic effect of PpIX and hydrogen peroxide was observed in-vivo. These preliminary results demonstrate an effective cancer treatment modality. [ABSTRACT FROM AUTHOR]

• Partial or complete decoloration of stains due to melanins is difficult. • Sodium percarbonate and carbamide peroxide reduce the color of the stain. • The combination with a gel allowed the treatment on marble from Vatican Gardens. The blackening of stone artifacts in the outdoor environment can be partially attributed to the presence of melanin and melanoidin-based pigments, produced by microorganisms such as fungi and bacteria. Generally, these dark patinas were found associated with biological colonization and it remains on the stone surface even after several applications of biocide and cleaning operation. The removal of these stains is considered one of the most difficult conservative operations, due to the impossibility of using dangerous chemical products both for the operator and for the stone surface. Hydrogen peroxide has traditionally been used for this purpose, while in this study has been tested the performance of sodium percarbonate and carbamide peroxide, both a stabilized form of hydrogen peroxide, on Watermelon seeds, rich in melanin, and Carrara marble stained by microbial melanin. It has been observed that the cleaning treatment with these two agents significantly reduces the color produced by melanins. Based on the results of this test, bleaching agents, such as carbamide peroxide and sodium percarbonate was used combined with a gel on some marble artifacts surfaces inside the Vatican Gardens, where they visually reduced staining. [ABSTRACT FROM AUTHOR]

• An O – g – C 3 N 4 /H – ZSM-5 composite was synthesized by green synthesis using natural perlite and urea. • The photocatalytic activity was investigated via the degradation of RR 195 under solar light without using H 2 O 2. • The oxygen doping into g – C 3 N 4 improved the photocatalytic activity. A novel oxygen-doped graphitic carbon nitride and zeolite (H - ZSM-5) composite (O – g – C 3 N 4 /H - ZSM-5) was synthesized using hydrogen peroxide and urea as the oxygen and g – C 3 N 4 precursors, respectively, and perlite as the zeolite source, via calcination at 550°C. BET N 2 adsorption - desorption analysis verified that the 40%O – g – C 3 N 4 /H - ZSM-5 composite had a high surface area of 259.13 m2/g with mesopores and micropores, and X-ray photoelectron spectroscopy (XPS) confirmed the existence of the O atom in the g – C 3 N 4 framework. The obtained O – g – C 3 N 4 /H - ZSM-5 catalyst showed excellent photocatalytic performance for the photodegradation of RR 195, approximately 96.6% with a high rate constant of 0.1167min−1 under solar light irradiation without the use of H 2 O 2. It also exhibited remarkable stability and long-term recyclability, with the photodegradation efficiency of RR 195 above 91%. In conclusion, the O – g – C 3 N 4 /H - ZSM-5 composite photocatalyst is suitable for numerous applications in the field of the photocatalytic degradation of organic pollutants. [ABSTRACT FROM AUTHOR]

The current knowledge of virginiamycin (VM) degradation kinetics at processing conditions observed in commercial ethanol production facilities is very limited. This knowledge is critical for assessing the feed and animal-derived food safety risk of the presence of VM residues in dried distillers grains with solubles (DDGS). A bioassay method was optimized to quantify the VM residues in a matrix sample obtained from distillation at an ethanol production facility. There were no significant differences on the VM degradation kinetics among the pH values of the distillation matrix sample used in the DDGS production (P = 0.98). Increasing the distillation temperature enhanced the reduction of VM (P < 0.01) reaching 70% degradation at 95 °C. The log-linear model was able to characterize the VM degradation kinetics with D-values ranging from 19.4 to 43.3 min at 70-95 °C. The M1 subunit was less heat-resistant with D-values ranging from 10.4 to 23.6 min. Distillation temperature conditions commonly used during the DDGS production process significantly degrades VM providing vital information for ethanol and food animal producers on the potential risk of the presence of antimicrobial residues in the final DDGS product. [ABSTRACT FROM AUTHOR]

[Display omitted] • Texture prevails over heteroatom content in CO 2 uptake within 1–25 bar and 273–323 K. • N-O-doping reduces textural properties but enhances CO 2 /N 2 selectivity up to 5 bar. • Heteroatom doping increases the isosteric heat of adsorption at low coverage. • Tap density is a key parameter affecting fixed-bed column breakthrough performance. This study shows the substantial impact of textural properties, with greater weight than N-doping, on CO 2 adsorption by carbon materials over a pressure range from 1 to 25 bar and a temperature range from 273 to 323 K. It also highlights the importance of providing volumetric CO 2 adsorption capacities when presenting newly developed materials. These results were obtained by exploring the influence of O- and N-doping on CO 2 uptake on 14 activated carbons (ACs) with distinct specific surface areas, from 1736 to 3200 m2/g, and micropore fractions from 37 to 96 %. Based on 3 commercial ACs, N content was maximized by hydrogen peroxide oxidation and urea treatment, reaching around 11 at.%. O-N-doping mainly impacted the largest pores, reducing material textural properties and thus CO 2 adsorption, although it improved CO 2 /N 2 selectivity, especially up to 5 bar and between 273 and 323 K. The contribution of heteroatoms to CO 2 uptake was particularly significant at low pressures and high temperatures, with threshold pressures increasing at higher temperatures. Breakthrough simulations were also carried out and the results demonstrate that, despite a lower specific surface area, the O-doped material exhibited longer breakthrough times than its commercial counterpart. This can be attributed to a balance between CO 2 adsorption capacity, governed by the textural properties, and tap density, i.e., adsorption capacity per unit volume. [ABSTRACT FROM AUTHOR]

• Hybrid light associated with carbamide peroxide potentiates bleaching effectiveness. • Hybrid light applied to carbamide peroxide with TiO 2 potentiated dental bleaching. • Carbamide peroxide with TiO 2 did not potentiate color change in the absence of light. The effectiveness of dental color change was assessed by incorporating titanium dioxide (TiO 2) into 37% carbamide peroxide bleaching agent associated with hybrid light. Fifty bovine incisors were selected to receive the bleaching treatment, and separated into five groups (n = 10): 35% hydrogen peroxide (HP) (Whiteness HP, FGM/HP); 37% carbamide peroxide (CP) (Whiteness SuperEndo, FGM/CP); CP + hybrid light (HL) (CP HL); CP + 1% TiO 2 (CP TiO 2); CP TiO 2 + hybrid light (CP TiO 2 HL). The bleaching gels were applied to the dental surface for 30 min. Hybrid light (Whitening Plus, DMC/infrared laser diodes + blue LEDs +violet LEDs) was applied with 1 min of active light, alternating with 1 min of pause. A spectrophotometer (VITA Easyshade® Advance, Vita) was used to determine the color of the dental elements at baseline and time points after the 1st, 2nd and 3rd bleaching sessions. Color change effectiveness was evaluated using Vita Classical, CIEL*a*b*, WI D and ΔE ab , ΔE 00 and ΔWI D parameters. Generalized mixed linear models for repeated measures (α = 5%) showed significant decrease in Vita Classical scores and a* and b* values, as well as an increase in L* and ∆W ID values for all the groups. Higher color change values for ΔE ab were observed for CP HL and CP TiO 2 HL, while those of ΔE 00 and ΔWI D were higher for CP TiO 2 HL at the end of the bleaching treatment. Hybrid light applied with TiO 2 incorporated into CP potentiated the effectiveness of the color change in the tooth structure. [ABSTRACT FROM AUTHOR]

• Lighter teeth benefit from the use of 35% hydrogen peroxide or 37% carbamide only. • Changing the color of darker teeth is potentiated with violet LED light. • Violet LED used alone did not present acceptability bleaching effect. The effectiveness of in-office bleaching protocols performed with violet LED light either combined with a bleaching agent containing 37% carbamide peroxide, or not, was determined by comparing teeth with different degrees of darkening. Eighty bovine incisors were separated into groups of "light" teeth (luminosity greater than or equal to B3) and "dark" teeth (less than or equal to A3.5) to receive the protocols: HP - 35% hydrogen peroxide (Whiteness HP), CP - 37% carbamide peroxide (Whiteness SuperEndo), LED - violet LED light (Bright Max Whitening), CPLED - CP associated with the LED. For color analysis the CIEL*a*b* e WI D , ΔE ab , ΔE 00 e ΔWI D parameters were used. Data were analyzed using Mann-Whitney, Kruskal-Wallis, Dunn, Friedman or Nemenyi tests (α = 5%). HP and CP resulted in similar color change values (ΔE ab , ΔE 00 e ΔWI D) for light and dark teeth (p > 0.05). Dark teeth showed better bleaching effectiveness (ΔE ab , ΔE 00 e ΔWI D) than light teeth when CPLED was used (p < 0.05). LED showed color change that were below the limits of acceptability and perceptibility for ΔWI D. light teeth are effectively bleached with the use of HP or CP, whereas dark teeth respond better to treatment with the CPLED protocol. Violet LED used alone did not show a satisfactory result. [ABSTRACT FROM AUTHOR]

To effectively control the escape of odorous chemicals like trichloroethylene (TCE) in soil remediation sites, a novel technology for iron-loaded bentonite activated urea peroxide (FBT/UHP) was developed in this study. This was significantly higher than the 51.40% removal in the untreated bentonite and UHP (BT/UHP) system. The stability test revealed that FBT remained stable after five uses. The hydroxyl radical was primarily responsible for the degradation process, accounting for almost 82.74% of total TCE removal. Intermediate identification and theoretical calculations further analyzed the possible degradation pathways of TCE. Intermediate identification combined with theoretical calculation further analyzed the potential degradation pathways of TCE. According to experimental results, the FBT/UHP system decreased the TCE cumulative relative escape rate by almost 91.90%. In summary, the FBT/UHP system shows promising potential for controlling TCE and other odour leakages during soil remediation at pesticide sites. • An odor control technology involving FBT activated UHP has been developed. • Hydroxyl radical was the main reason for the degradation of TCE by FBT/UHP system, accounting for 82.74% of the total of TCE removal. • The possible degradation pathways of TCE were proposed. • The FBT/UHP system demonstrates remarkable effectiveness in real field applications, greatly reducing TCE soil-air emissions. [ABSTRACT FROM AUTHOR]

[Display omitted] Arylnitromethanes were prepared by oxidation of aldoximes with sodium perborate or with urea hydrogen peroxide in the presence of boric acid. The use of urea hydrogen peroxide complex provides better and more stable yields of nitro compound and allows one to halve an acetic acid consumption. Only E -aldoximes are oxidized to arylnitromethanes while Z -isomers are transformed into complex mixtures not containing arylnitromethanes. [ABSTRACT FROM AUTHOR]

• Carbamide peroxide into polymeric nanoparticles revealed improved stability. • Lower carbamide peroxide nanoparticles were in vivo effective at bleaching. • Carbamide peroxide nanoparticles showed no in situ pulp damage. Carbamide peroxide is the popular home dental whitening agent. However, it has critical stability. Nanoparticles have been applied to develop products with advantages properties as better efficacy and stability increase. The aim of this study was the characterization of carbamide peroxide polymeric nanoparticles, their bleaching efficacy, effects on pulp damage and stability evaluation. Particle size demonstrated a spherical morphology and bimodal distribution (11 and 398 nm). Nanoparticles presented high entrapment efficiency (98.94%) and the zeta potential value was slightly positive (+10.26 mV). Regardless of the zeta potential, the steric effect may contribute to carbamide peroxide nanoparticle stabilization. The stability studies conducted at room temperature suggested that carbamide peroxide nanoparticles could maintain all the parameters evaluated (size, polydispersity index, zeta potential, entrapment efficiency, pH and content) for at least 90 days. Instability index was determined by dispersion analyzer (LUMiSizer ®), was 0.018, and the light transmission profile did not present sedimentation. Carbamide peroxide nanoparticles were able to prevent thermal degradation and photostability. Clinical efficacy of the whitening gels was obtained by color change in the spectrophotometer and the results showed that all the evaluated gels containing the nanoparticles (0, 1, 2 and 5% of real carbamide peroxide) were effective at bleaching after 2 h of home whitening treatment (during 30 days). After the treatment, the extracted teeth showed no in situ pulp damage by histological evaluation. The nanotechnology strategy of converting carbamide peroxide into polymeric nanoparticles revealed a new product with improved stability, a good approach for carbamide peroxide delivery. [ABSTRACT FROM AUTHOR]

[Display omitted] • UHP pretreatment enhanced the production of SCFAs in WAS anaerobic fermentation. • UHP pretreatment contributed to WAS disintegration significantly. • UHP pretreatment facilitated the generation and transformation of intermediates. • OH, O 2 and urea were the major contributors to the increased WAS disintegration. • Functional microbials and genes related with acetate production were upregulated. Improving the anaerobic treatment performance of waste activated sludge (WAS) to achieve resource recovery is an indispensable requirement to reduce carbon emissions, minimize and stabilize biosolids. In this study, a novel strategy by using urea hydrogen peroxide (UHP) to enhance SCFAs production through accelerating WAS disintegration, degrading recalcitrant substances and alleviating competitive suppression of methanogens. The SCFAs production and acetate proportion rose from 436.9 mg COD/L and 31.3% to 3102.6 mg COD/L and 54.1%, respectively, when UHP grew from 0 to 80 mg/g TSS. Mechanism investigation revealed that OH, O 2 and urea were the major contributors to accelerate WAS disintegration with the sequence of OH> O 2 > urea. Function microbes related to acidification and genes associated with acetate production ([EC:2.3.1.8] and [EC:2.7.2.1]) were upregulated while genes encoding propionic acid production ([EC:6.4.1.3] and [EC:6.2.1.1]) were downregulated. These results raised the application prospects of UHP in WAS resource utilization. [ABSTRACT FROM AUTHOR]

Glyphosate is one of the most widely used pesticides globally. However, glyphosate and its residual metabolite, aminomethyl phosphonic acid (AMPA), are persistent and mobile chemicals. Large amounts of glyphosate residue can accumulate in the environment, causing adverse effects in organisms. Urea hydrogen peroxide (UHP) in soil slow-release H 2 O 2 undergoes a Fenton-like reaction with Fe2+, and the resulting hydroxyl radical (·OH) degrades glyphosate. This experiment investigated the effects of three fertilisers (UHP, ferrous sulphate, and urea) on the degradation of glyphosate in agricultural soils and their effects on soil ammonia nitrogen effectiveness and enzyme activity. Among all treatments, the half-life of glyphosate in the mixed application of UHP and ferrous sulphate was the shortest (11.9 d), and its degradation rate was the highest (70.64%), degrading within 28 d. Throughout the experimental cycle, in 1–7 d, the application of UHP reduced the effect on indigenous microorganisms and maintained nitrogen availability and enzyme activity in the soil; in 7–14 d, the mixed application of UHP and ferrous sulphate alleviated the nitrification of soil nitrogen and reduced the loss of ammonia from the soil; in 14–28 d, the mixed or single application of UHP and ferrous sulphate and the low dose of glyphosate remaining in the soil had a catalytic effect on enzyme activity, promoting the secretion of catalase and nitratase, which participate in soil glyphosate degradation and nitrogen cycling. Therefore, this study provides a scientific basis for the in-situ remediation of herbicide-contaminated soil in agricultural fields using chemical fertilisers. [Display omitted] • Potential role of urea hydrogen peroxide in degradation of glyphosate in soil. • A method for in-situ remediation of glyphosate contaminated soil. • Urea hydrogen peroxide slowly releases H 2 O 2 and produces Fenton-like reaction with Fe2+. • Glyphosate degradation affects soil nitrogen and enzyme activity. • Urea hydrogen peroxide can increase the content of ammonium nitrogen in soil. [ABSTRACT FROM AUTHOR]

Highlights • Process model is developed for interactions of consistency of pulp, temperature and dosage of carbamide peroxide on Kappa number. • Spectral analysis of pulp bleaching with carbamide peroxide is done using FTIR, XRD and FT-Raman spectroscopy. Abstract The study focuses on delignification of Kraft pulp using carbamide peroxide as bleaching agent. The Kappa number reduction of bleached pulp is favored at low consistency of pulp and higher reaction temperature. The optimal Kappa reduction was achieved at temperature of 68 °C, 0.8 g of carbamide peroxide per 100 ml of solution and 2% consistency in the range of variables studied. Fourier transform infrared spectral analysis done on bleached pulp to determine bond stretches and bending vibrations. X ray diffraction spectral data observation provided that the crystallinity index increased from 81.7% before bleaching to 85% after bleaching which indicates the removal of amorphous species in sample. FT-RAMAN spectral analysis concludes the possible conformational changes pre and post bleaching. The absence of some native lignin bands post bleaching indicates lignin removal. Scanning electron microscope images of bleached pulp samples were observed with less amounts of fibrillar type lignin network on surface of pulp fibers when compared to unbleached samples. The activation energy and rate constants were determined for delignification of pulp using carbamide peroxide process. Sequential treatment of Kraft pulp with carbamide peroxide and sodium percarbonate were also evaluated. [ABSTRACT FROM AUTHOR]

Background The effects of HP-based products upon dental enamel and dentin are inconclusive. Aim To evaluate changes in micromorphology and composition of calcium (Ca) and phosphate (P) in enamel and dentin after the application of 37.5% hydrogen peroxide (HP) and 35% carbamide peroxide (CP) Methods Crowns of 20 human teeth were divided in two halves. One half was used as control specimen and the other as experimental specimen. The control specimens were kept in artificial saliva, and the experimental specimens were divided into four groups (n = 5 each): group 1 (enamel HP for 45 min); group 2 (dentin HP for 45 min); group 3 (enamel CP for 90 min); and group 4 (dentin CP for 90 min). The morphological changes were evaluated using confocal laser scanning microscopy (CLSM), while the changes in the composition of Ca and P were assessed using environmental scanning electron microscopy combined with a microanalysis system (ESEM + EDX). The results within each group and between groups were compared using the Wilcoxon test and Mann–Whitney U-test, respectively (p < 0.05). Results Similar morphological changes in the enamel and no changes in dentin were assessed with both products. Ca and P decreased in enamel and dentin, without significant differences between them or with respect to their control specimens (p > 0.05). Conclusions When bleaching products with a neutral pH are used in clinical practice, both, the concentration and the application time should be taken into account in order to avoid possible structural and mineral changes in enamel and dentin. [ABSTRACT FROM AUTHOR]

Ni-Al 2 O 3 nanocomposite coatings were electrodeposited from Watt's bath containing alumina nanoparticles, dispersed with the aid of carbamide. The effect of carbamide concentration on the amount of embedded alumina nanoparticles, zeta potential, microstructure, microhardness and tribological behavior of nanocomposite coatings were investigated. The results revealed that using of carbamide in the range of 10–15 g/L increased the microhardness up to 85% compared with the coating fabricated without carbamide. The adsorption of alumina nanoparticles increased from 4.6 vol% to 11.3 vol% by the aid of carbamide and it also caused grain refinement in the nickel matrix. Increasing the carbamide concentration up to 15 g/L led to decrease in the wear rate, approximately to 30% of the coating electrodeposited without carbamide. [ABSTRACT FROM AUTHOR]

Motility of spermatozoa in most freshwater teleost species is suppressed by the osmolality of the seminal plasma in the testes, sperm ducts and initiated by a decrease of osmolality upon spawning in fresh water. We hypothesized that, similarly to internally fertilising fish species, spermatozoa of freshly stripped sperm, when injected directly into the ovary through the oviduct, will remain inactivated and maintain its fertilisation capacity for extended periods. Fertilisation is expected to occur after ovulated oocytes with spermatozoa on their surfaces are released into the water. To test this hypothesis, experiments were carried out on carp ( Cyprinus carpio ) as a model fish. Stripped and pooled sperm samples were injected by catheter into the ovarian cavity through the oviduct 2 h and 12 h before expected spawning. To prevent any loss of gametes the genital area of treated females were stitched by a standard protocol used in large-scale hatchery systems. At ovulation, eggs were stripped and fertilised with salt-carbamide solution. All sperm-injected females produced some fertilised eggs that developed normally while fertilisation rates varied considerably (24.2–81.2%). This proof of principle experiment demonstrates the potential for routine use as alternative to in vitro fertilisation for the propagation of fish species. [ABSTRACT FROM AUTHOR]

Soil compaction is a widespread phenomenon in intensive agriculture and can severely hamper root growth and crop yield. Hydrogen peroxide urea (UHP) has been employed as an effective measure for oxygenation in dryland systems. However, whether oxygenation via UHP could alleviate negative effects on vegetable growth induced by soil compaction is unknown. A pot experiment involving different soil bulk densities (1.2, 1.5, and 1.7 g cm−3) with oxygenation at different stages of development (seedling stage, mid-growth stage) was conducted in amaranth (A. mangostanus), with non-oxygenation at different soil bulk densities as a control. Increased soil compaction affected vegetative growth of both the shoot and root system of amaranth and caused yield reduction. Oxygenation in topdressing significantly improved soil O 2 supply until the harvest period, imparted 17.9–20.4 % additional O 2 to soils. Increased O 2 supply alleviated soil compaction stress, and amaranth yield increased by 5.50–16.1 % at the same soil bulk density compared with control, respectively. Oxygenation during the mid-growth stage had a superior effect on vegetable growth compared to oxygenation at the seedling stage, coincident with the higher oxygen demand during mid-growth in amaranth. Oxygenation promoted root growth in compacted soil, and increased root length by 76.3 % at a soil bulk density of 1.5 g cm−3 and 74.7 % at a bulk density of 1.7 g cm−3 compared with control. The alleviatory effect on the root system can be linked to increased root catalase activity and decreased malondialdehyde content. Oxygenation furthermore increased phosphorus (P) bioavailability by increasing both phosphatase activity and the relative abundance of phosphate-solubilizing bacteria (Firmicutes and Proteobacteria), with an increase in DGT-P by 10.5–23.6 % compared to control. The soil bacterial co-occurrence network at a soil bulk density of 1.5 g cm−3 with oxygenation was more similar to 1.2 g cm−3 soil compaction with oxygenation, which possessed most complex and the proportion of connectors, but was dissimilar from 1.7 g cm−3 soil compaction with oxygenation, which was less stable microbial network structure. Improvement of O 2 content could build a healthy and stable rhizosphere bacterial community, and increased the proportion of important nodes in the network, which was conducive to the collaborative development of microorganisms to face compaction stress. And bacterial community structure with oxygenation in compacted soil could recovery to near normal microbiology community structure. The research provides a theoretical and technical framework for the development of strategies that can maximize crop yield in compacted soil. [Display omitted] • Oxygenation increased soil dissolved oxygen concentration. • Oxygenation promoted root elongation, limiting oxidative damage to root. • Oxygenation alleviated soil compaction stress by providing more plant-available P. • Oxygenation led to establish a healthy and stable rhizosphere bacterial community. [ABSTRACT FROM AUTHOR]

• Bleaching without light leads to the lowest buccal surface and pulpal temperatures. • Continuous application of LED for 30 min led to the highest temperatures. • The use of LED leads to an increase in pulp and buccal surface temperatures. • Fractionated or continuous application of violet LED for 20 or 30 min leads to greater effectiveness of color change. Dental color change and the temperature of the pulp chamber and of the buccal surface were evaluated during bleaching with 37% carbamide peroxide (CP) with continuous vs fractionated violet LED light protocols. Bovine incisors received in-office bleaching for 30 min using different light protocols (Bright Max Whitening, MMOptics). Teeth were separated into groups (n = 10): HP) 35% hydrogen peroxide (Whiteness HP, FGM)/no light; CP) 37% carbamide peroxide (Whiteness SuperEndo, FGM)/no light; CP10) CP+10 min of continuous light; CP20) CP+20 min of continuous light; CP30) CP+30 min of continuous light; CPF) CP+20 cycles of 60 s light / 30 s no light (fractionated). Color evaluations were performed at different times. Evaluations of pulp and buccal surface temperatures were performed before and throughout the 30 min of bleaching. Generalized linear models for repeated measures over time were applied to the data (α=5%). After the 1st session, CP20 and CP30 had significantly lower b* values ​​than CP and CP10 (p = 0.0071). For ΔE ab and ΔE 00 , CPF, CP20 and CP30 showed the highest color change among the treatments after the third bleaching (p <0.05). For temperature evaluations, CP30 showed higher pulp and buccal surface temperatures than the other protocols (p <0.0001) after 20 min. Fractionated or continuous application of violet LED for 20 or 30 min leads to greater effectiveness of color change. All protocols with the application of LED led to an increase in pulp and buccal surface temperatures during bleaching, although the fractionated application appeared to be safer than the use of continuous light. [ABSTRACT FROM AUTHOR]

• Carbamide peroxide and violet LED could be used on early-stage eroded/abraded teeth. • Violet LED increased the efficacy of 20% and 45% carbamide peroxide. • Bleaching with carbamide peroxide did not affect enamel surface properties. This study evaluated enamel with early-stage erosion/abrasion following bleaching with 20% and 45% carbamide peroxide (CP) gels containing fluoride (F) and irradiated with violet LED (LED). Enamel blocks were immersed in 1% citric acid (5 min) and artificial saliva (120 min) three times to produce early-stage enamel erosion. Simulated toothbrushing was performed only after the first saliva immersion, to provoke enamel abrasion. The erosive/abraded enamel samples were submitted to (n=10): LED/CP20, CP20, LED/CP20_F, CP20_F, LED/CP45, CP45, LED/CP45_F, CP45_F, LED, and control (without treatment). The pH of the gels was assessed, and color (ΔE 00) and whiteness index (ΔWI D) changes were calculated after cycling (T 1), and 7 days from bleaching (T 2). Enamel surface roughness average (Ra) and Knoop microhardness (kg/mm2, %SHR) were evaluated at baseline (T 0) at T 1 and T 2. Scanning electron microscopy evaluated the enamel surface morphology at T 2. The gels' pH was neutral and CP20 and CP45 exhibited no differences in ΔE 00 and ΔWI D (p>0.05) but LED increased these parameters for CP20_F and CP45. Erosion/abrasion significantly decreased mean kg/mm2, and the LED group was the only one not increasing microhardness after bleaching (p>0.05). None of the groups fully recovered the initial microhardness. All groups exhibited %SHR similar to the control (p>0.05) and the increase in Ra was detected only after erosion/abrasion. CP20_F groups exhibited a more preserved enamel morphology. Light irradiation combined with low-concentrated CP gel promoted a bleaching effect comparable to the high-concentrated CP. The bleaching protocols did not adversely impact the surface of early-stage eroded/abraded enamel. [ABSTRACT FROM AUTHOR]

Organoarsenics in soil urgently desired careful remediation. Unfortunately, it did not receive enough attention. Herein, we report a versatile Fe2+/Urea Hydrogen Peroxide (UHP) process for not only organoarsenic remediation but also nitrogen supplement in soil. Insight mechanism was firstly studied in water. Roxarsone (ROX) was efficiently degraded by 99.6% following a kinetics of v= 33.91 × [ROX]× [UHP]1.2175 × [Fe2+]1.8990. Aromatic ring cleavage of ROX was realized, resulting in a satisfying mineralization performance. After degradation processes, 88.5% of total arsenic was removed from the solution at pH 5.0 via adsorption processes by generated Fe(OH) 3 particles. The particles showed much higher adsorption capacity to inorganic arsenic species than that to organoarsenic. The degradation of ROX facilitated the immobilization of total arsenic. The remediation was further carried out in soil. Satisfying removal of ROX (95.5%) and immobilization of total arsenic (89.3%) was achieved. More importantly, 94.2%− 94.6% less arsenic was transferred into the lettuce. By the injection of Fe2+/UHP, a sixteen times higher concentration of total nitrogen was achieved. The growth of lettuce was significantly promoted due to the multi-functions including arsenic immobilization and nitrogen supplement. The achievements suggested Fe2+/UHP system potentials in applications for organoarsenic remediation in soil and also soil amelioration. [Display omitted] • The first approach for soil remediation by a Urea Hydrogen Peroxide based process. • Both organoarsenics and inorganic arsenic were efficiently remediated. • Nitrogen supplement was achieved during the remediation processes. • The transfer of arsenic from soil to plants/crops was intercepted. • The growth of plant was promoted due to arsenic remediation and nitrogen supplement. [ABSTRACT FROM AUTHOR]

Tooth bleaching is a simple technique performed with gels based on hydrogen peroxide molecules responsible for removing the tooth structure's pigmentation. The effects of the overuse of these agents on the tooth structure are not well established. Energy dispersive X-ray fluorescence (EDXRF) can be employed to analyze objects of biological origin as bone and tooth. It is very suitable analytical technique to detect demineralization processes in these tissues. The objective of this study was to use x-ray fluorescence to evaluate the effects on mineral content of enamel submitted to eight-week protocols of home bleaching gels (10% carbamide peroxide and 9.5% hydrogen peroxide), as well as bleaching strips. Four enamel fragments obtained from five teeth were subjected to bleaching for 8 weeks: Group 1— artificial saliva; Group 2—10% carbamide peroxide gel, 6 h daily; Group 3—9.5% hydrogen peroxide gel, two 30-minute applications; and Group 4—bleaching strips, twice daily for 30 min. The change in mineral content was assessed weekly using X-ray fluorescence (Artax 200). Differences were basically found in Group 4 for the concentrations of Ca and P after treatment with bleaching strips containing 10% hydrogen peroxide. For the Ca/P ratio, the differences were found in Group 2—15% carbamide peroxide ( p < 0.05). X-ray fluorescence proved to be a suitable method for the evaluation of the mineral content, presenting the advantage of being able to evaluate the same area at different stages of the methodology. [ABSTRACT FROM AUTHOR]

Cattle slurry storage is a major point source for methane (CH 4) and ammonia (NH 3) emissions globally. Efficacy of an oxygen-based amendment in reducing these emissions was investigated. Two 1.6 kg cattle slurry incubations, each lasting for 40-days, were carried out in a climate-controlled chamber with CH 4 and NH 3 emissions measured. Multiple peroxide sources acting as a source of oxygen were tested to examine how compatible they were for addition to cattle slurry. An amendment comprising of hydrogen peroxide (HP) and potassium iodide (KI) has been highlighted as method to reduce CH 4 emissions from this source. While urea hydrogen peroxide and sodium percarbonate reduced CH 4 emissions, they increased the slurry pH and subsequently NH 3 emissions by 209 and 42%, respectively. Hydrogen peroxide did not infer any pH increase upon the slurry and therefore no increase in NH 3 emissions was observed. Hydrogen peroxide and KI were able to reduce CH 4 emissions by 63% during slurry storage. The use of this treatment on a larger scale system should be considered in the future considering the large reductions achieved. [Display omitted] • A mix of hydrogen peroxide and potassium iodide abated 63% of methane emissions during storage. • The addition of urea to cattle slurry increased NH 3 emissions by 209%. • Agitation caused by the addition of hydrogen peroxide and potassium iodide did not increase NH 3 emissions. [ABSTRACT FROM AUTHOR]

To evaluate the effect of smoking on tooth whiteness and color change after at-home bleaching. The present investigation is a cohort study with 40 patients (N=40), assigned into 2 groups: NS- non-smokers (n=24) and S- smokers (n=16). At-home bleaching was performed with 22% carbamide peroxide (CP) using individual trays for 1 h a day for 14 days. CIELAB color coordinates were obtained from the six upper anterior teeth (CI- central incisors, LI- lateral Incisors and C- canines) using a Vita Easy Shade spectrophotometer before bleaching (D0-baseline), one day (D1), 15 days (D15) and one month (D30) after the end of the treatment. Whiteness index for dentistry (WID) and CIEDE2000 color difference (ΔE00) were calculated and used to evaluate the bleaching efficacy. Whiteness (ΔWID) and color (ΔE00) changes were compared between NS and S in distinct dental groups using the Mann-Whitney test (α=0.05). The corresponding 50:50% acceptability thresholds were used to analyze the whiteness (WAT) and color (AT) differences obtained in this study. For all teeth groups, NS showed similar median WID values than S at baseline (D0) (p>0.05), but higher values than S for the other evaluation times (D1, D15, and D30) (p≤0.05).For ΔWID values, NS showed greater differences values (D1-D0, D15-D0, and D30-D0) for CI and C when compared to those of S (p≤0.05), and all these differences were above WAT value. In addition, although NS showed higher ΔWID values than S for the period D30-D1 (p≤0.05), both of them were below WAT value. ΔE00 values showed similar behavior than ΔWID for all the groups. Smoking influenced on the whiteness and color alterations, after at-home bleaching treatment using 22% CP. However, the observed whiteness and color alterations were clinically acceptable for smokers. [ABSTRACT FROM AUTHOR]

Whitening or bleaching is a procedure that improves the colour of the teeth and has an important role in the aesthetic look of the patient. It is known that standard materials used for whitening (hydrogen peroxide and carbamide peroxide) can have harmful effects on the tooth structure so in the recent years, emphasis has been put on using natural ingredients. Studies are being carried to see the efficacy of these natural products. The authors have reviewed the information available from a number of 12 studies that had the objective to demonstrate the efficacy of the natural ingredients on teeth whitening. The studies have been separated in 3 groups: group A baking soda, group B charcoal and group C citric acid. Each of them consists of 4 studies. In all cases, the colour of the teeth has been improved. Some studies showed that the natural ingredients don't have a higher abrasivity than the toothpastes and are safe for use. Baking soda has an antibacterial role, has a low abrasivity and is compatible with the sodium fluoride found in toothpastes. Charcoal has a good whitening potential, but it is recommended to be used carefully because it cand induce enamel lesions. The citric acid has an antibacterial and anti-inflammatory role and the best concentration for teeth whitening is the 5% one. None of the studies showed great damage of the enamel and dentin structure. All the natural ingredients had similar esthetic results with the synthetic products but none of them had a greater effect regarding tooth substance loss. It has been demonstrated that natural ingredients have a good capacity of teeth whitening and some of them can reduce the plaque accumulation and increase the gum health. Whether they are used in a pure form or as ingredients in different gels or toothpaste, their good aesthetic results and reduced side effects recommend them in the bleaching procedure. Further studies should be carried to find the best formula for a natural whitening product. [ABSTRACT FROM AUTHOR]

In recent years, there has been an increased demand for improvement in the appearance of natural teeth. The conservative technique of tooth bleaching has gained attention and acceptance from both patients and clinicians. Despite increased popularity, there is controversy surrounding the adverse effects of bleaching on dental restorative materials. This article reviews the effects of bleaching agents on major categories of dental restorative materials and provides evidence-based recommendations to the clinicians and researchers. Current literature reveal that bleaching might have a detrimental effect on restorative materials. However, because of the variability in experimental design, there is a lack of consensus concerning the bleaching effects on restorative materials. A standardized and reproducible guideline for assessment of bleaching effects on restorative materials needs to be established and verified by future studies. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Tooth bleaching using violet system based on LED and low concentration bleaching agent. • Total absence of dental sensitivity during and after tooth bleaching. • Aesthetic procedure. Abstract The use of violet LED was recently introduced as a new alternative technique to perform tooth bleaching, associated or not with bleaching agents. This paper shows a tooth bleaching clinical case report performed in a 26-year-old woman, using a violet LED with 10% carbamide peroxide (CP). The tooth bleaching protocol was performed in 3 sessions. Fifteen irradiations using a violet light system (BMW, MMoptics, São Carlos, SP, Brazil) were done during 30 s (on) and 60 s (off) without bleaching gel, and more 5 irradiations associated to 10% CP. Upper and lower arches were irradiated separately. The total procedure time was 30 min. Subjective and objective color assessments were performed using Vitapan Classical shade guide and VITA Easyshade spectrophotometer, respectively. Dentin sensitivity was measured using a visual analogue scale. The use of violet LED associated to a low concentration carbamide peroxide successfully promoted tooth bleaching and no side effects i.e. dentin sensitivity during and post treatment was observed. [ABSTRACT FROM AUTHOR]

• Fe(II)/UHP process was developed to improve sludge dewatering • •OH from Fe(II)/UHP liberated the EPSs-bound and cells-bound water • •OH from Fe(II)/UHP reduced centrifugal liquor viscosity and electronegativity • Fe(II)/UHP reduced solid-liquid interface interaction of WAS • Fe(II)/UHP increased hydrophobicity, flocculation, and flowability of WAS The treatment and disposal of sludge is a complex environmental problem because of the high moisture content. Herein, We reported the process of Fe(II) activating Urea hydrogen peroxide (UHP) to improve waste activated sludge (WAS) dewaterability for the first time. Fe(II)/UHP was proven to significantly improve WAS dewaterability. Specifically, under the optimal conditions with 60/35-Fe(II)/UHP mg/g TSS, the CST, SRF, and WC SC of WAS reduced from 215.3 ± 7.5s, 9.2 ± 0.32 (× 1012 m/kg), and 92.2 ± 0.7% (control) to 62.3 ± 4.3s, 2.8 ± 0.09 (× 1012m/kg), and 70.4 ± 0.4%, respectively. Further analysis revealed that •OH was generated in the Fe(II)/UHP system and played the dominant role in enhancing WAS dewaterability. •OH was found to attack extracellular polymeric substances (EPSs) and cells, causing EPSs fragmentation and decomposition part of EPSs into micro-molecule organics or even inorganics, and leading to cell destruction, thus liberating the EPSs-bound and cells-bound water. •OH also degraded the protein in centrifugal liquor (CL) into micro-molecule organics such as amino acids, which could reduce the viscosity and electronegativity of CL. The above facts ultimately reduced solid-liquid interface interaction but increased hydrophobicity, flocculation, and flowability of WAS. Meanwhile, the broken WAS flocs were then re-flocculated via adsorption bridging and charge neutralization induced by Fe(II) and Fe(III). Moreover, Fe(II)/UHP treatment achieved the reduction and stabilization of heavy metals of dewatered sludge, which further enabled its land application. Finally, the Fe(II)/UHP process was found to be more attractive than the Fe(II)/persulfate, classical Fenton processes, and cPAM in terms of cost savings and practical implementation. : [Display omitted] [ABSTRACT FROM AUTHOR]

Titanium has been widely used as a preferred metallic biomaterial for bone tissue engineering scaffolds. So far, a number of techniques have been developed to produce porous-structured titanium, including the space holder method. However, a number of technological challenges are still present, such as the difficulties in controlling the geometry changes of space-holding particles during the compaction of titanium/space holder powder mixtures. In this research, a series of experiments were performed to investigate the compression behaviors of titanium/carbamide powder mixtures and determine maximum compacting pressures, considering the specific net energy expended during the process, the at-pressure relative density of powder compacts and the yield pressure derived from the load–displacement plots of powder compression cycles. The results showed that the titanium and carbamide powders exhibited dissimilar compression behaviors and titanium/carbamide powder mixtures exhibited intermediate compression behaviors of the monolithic titanium and carbamide powders. The yield pressures of titanium/carbamide powder mixtures, obtained from the Heckel plots and used as a measure for the appropriate compacting pressures, decreased with increasing volume fraction of carbamide in the mixture. The rule of mixtures was found to be applicable to predict the compression behaviors and the appropriate compacting pressures of titanium/carbamide powder mixtures. However, limitations of this model were recognized in the case of compacting mixtures with large volume fractions of carbamide space-holding particles ( x > 50%) and at high pressures ( P > 300 MPa). [ABSTRACT FROM AUTHOR]

Objectives: This meta-analysis was performed to evaluate the efficacy of potassium nitrate and sodium fluoride as desensitizing agents during tooth bleaching treatment. Data, sources and Study selection: An electronic systematic literature search was conducted in Cochrane Center Register of Controlled Trials, MEDLINE (PubMed) and EmBase in April, 2014 in English and without time restrictions. Study information extraction and methodological quality assessments were accomplished by two reviewers independently. Methodological quality was assessed by using the "Criteria for judging risk of bias in the 'Risk of bias' assessment tool". Dichotomous data was summarized by odds ratio (OR) with 95% confidence interval (CI) and continuous data was summarized by mean difference (MD) or standardised mean difference (SMD) with 95% confidence interval (CI). Statistical analyses were carried out by using Review Manager 5.2. For evaluation of percent of patients experiencing tooth sensitivity (POTS), the pooled OR of desensitizers vs. placebo was 0.45 (95% CI: 0.28-0.73, P = 0.29). The pooled SMD of desensitizers vs. placebo was −0.47 (95% CI: −0.77 to −0.18, P = 0.13) in evaluation of level of tooth sensitivity (LOTS). The results of shade evaluation remained inconsistent by evaluating subjective shade guide unit difference (ΔSGU or SGU) and objective colour difference (ΔE). Conclusions: This meta-analysis was performed to evaluate the efficacy of desensitizing agents, potassium nitrate and sodium fluoride, for tooth bleaching treatments. Potassium nitrate and sodium fluoride reduce tooth sensitivity while no consistent conclusion of tooth colour change was found. Clinical significance: Tooth sensitivity is a typical side effect associated with tooth bleaching procedures. Potassium nitrate and sodium fluoride are used widely to treat tooth sensitivity. This meta-analysis was performed to evaluate the efficacy of potassium nitrate and sodium fluoride as desensitizing agents during tooth bleaching treatment. [ABSTRACT FROM AUTHOR]

This study investigated the effect of two bleaching agents, 16% carbamide peroxide (CP) and 35% hydrogen peroxide (HP), on the mechanical properties and protein content of human enamel from freshly extracted teeth. The protein components of control and treated enamel were extracted and examined on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS–PAGE). Marked reduction of the protein matrix and random fragmentation of the enamel proteins after bleaching treatments was found. The mechanical properties were analyzed with Vickers indentations to characterize fracture toughness, and nanoindentation to establish enamel hardness, elastic modulus and creep deformation. Results indicate that the hardness and elastic modulus of enamel were significantly reduced after treatment with CP and HP. After bleaching, the creep deformation at maximum load increased and the recovery upon unloading reduced. Crack lengths of CP and HP treated enamel were increased, while fracture toughness decreased. Additionally, the microstructures of fractured and indented samples were examined with field emission gun scanning electron microscopy (FEG-SEM) showing distinct differences in the fracture surface morphology between pre- and post-bleached enamel. In conclusion, tooth bleaching agents can produce detrimental effects on the mechanical properties of enamel, possibly as a consequence of damaging or denaturing of its protein components. [ABSTRACT FROM AUTHOR]

A full account of our recently communicated method for the V 2 O 5 mediated bromolactonization of alkenoic acids is presented. Here we describe the extensive evaluation of the metal oxide catalyst, terminal oxidant, halide source, solvent system, and reaction temperature that resulted in optimal conditions employing 0.05 equiv V 2 O 5 , 3 equiv urea-hydrogen peroxide complex (UHP), and 3 equiv of NH 4 Br in an acetone:H 2 O (6:1) solvent system at room temperature. Additionally, we have expanded the substrate scope of the reaction with the aim of evaluating the functional group tolerance of the transformation. Further, we present preliminary data of a related halogenation of β-diketones with our optimal conditions. Finally, we probed the role of urea in the transformation. [ABSTRACT FROM AUTHOR]

[Display omitted] Herein, we describe an efficient, fast, mild and sustainable protocol for the oxidation of thiols using Urea Hydrogen Peroxide (UHP) to give the corresponding disulfides in good to excellent yields. The methodology uses polysorbate 80 as a greener solvent and catalyst which was, for the first time, recovered from the reaction medium and reused. [ABSTRACT FROM AUTHOR]

Abstract: Current research about tooth whitening shows that it is safe and effective when manufacturer's protocol is followed, yet there are risks of which the profession and users should be aware. This update provides a summary of current research and assessment of the safety and efficacy of tooth whitening regimens. Background: Tooth whitening has become one of the most frequently requested dental procedures by the public. The public has come to demand whiter, more perfect smiles and in response many choices for tooth whitening have been made available. These include home-based products such as toothpastes, gels, and films, as well as in-office based systems where products containing highly concentrated bleaching agents are applied under professional supervision. The profession and public have been aware of certain risks related to tooth whitening such as increased tooth sensitivity and gingival irritation. New research has shown that there are other risks such as tooth surface roughening and softening, increased potential for demineralization, degradation of dental restorations, and unacceptable color change of dental restorations. The new research is also focused on optimizing whitening procedures to reduce tooth sensitivity and to increase the persistence of the whitening. Methods: Current reports in the literature are reviewed that are related to the use of peroxide based whitening methods. These reports include in vitro studies for method optimization and mechanism as well as clinical studies on effects of various whitening regimens. Conclusions: When manufacturer's instructions are followed, hydrogen peroxide and carbamide peroxide based tooth whitening is safe and effective. Patients should be informed of the risks associated with tooth whitening and instructed on identification of adverse occurrences so that they may seek professional help as needed. [Copyright &y& Elsevier]

Objectives: To evaluate the effects of experimental protocols on bleaching effectiveness and hydrogen peroxide (HP) diffusion through enamel and dentine. Methods: Enamel/dentine discs were subjected to six bleaching sessions, consisting of 1 or 3 applications of 17.5% or 35%-HP gel for 5/15 min, or 37% carbamide peroxide (CP) gel for 10/ 20 min. Discs undergoing the regular protocol (35%-HP; 3 s 15 min) constituted the positive control group. Colour change (DE) was assessed (CIE L*a*b* system) after each session. HP diffusion was quantified (sessions 1, 3, and 6) in enamel/dentine discs adapted to artificial pulp chambers. Data were analysed by Pillai's Trace and Bonferroni test, or by one-way ANOVA and SNK/Tamhane's test (a = 5%). Results: All tooth-bleaching protocols significantly increased the DE values. A reduction in HP diffusion and no significant difference in DE compared with the positive control were observed for the following bleaching protocols: 17.5%-HP 3:15 min, at the 4th session; and 35%-HP 1 s 15 and 3 s 5 min, at the 5th session. HP diffusion in the 37%-CP 3 s 20 min bleaching protocol was statistically similar to that in the positive control. The other experimental bleaching protocols significantly decreased HP diffusion through enamel/ dentine discs, but the DE values were statistically lower than those observed in the positive control, in all sessions. Conclusion: Shortening the contact time of a 35%-HP gel or reducing its concentration pro- duces gradual tooth colour change and reduced HP diffusion through enamel and dentine. Clinical significance: A reduction in HP concentration, from 35% to 17.5%, in a bleaching gel or shortening its application time on enamel provides a significant tooth-bleaching improvement associated with decreased HP diffusion across hard dental tissues. Therefore, these protocols may be an interesting alternative to be tested in the clinical situation. [ABSTRACT FROM AUTHOR]

Abstract: Selective oxidation of sulfides to sulfoxides with urea hydrogen peroxide in the presence of the manganese complex of non-, partially and fully brominated meso-tetraphenylporphyrin, (MnTPPBrx(OAc) (x=0, 2, 4, 6 and 8)) is reported. Although, the maximum conversion was achieved in the case of MnTPPBr4(OAc), little difference was found between the catalytic activity of MnTPP(OAc), MnTPPBr2(OAc) and MnTPPBr4(OAc). MnTPPBr8(OAc) showed an unusually very low catalytic efficiency compared to the other manganese porphyrins. The presence of small amounts of acetic acid was shown to have significant effect on the total conversion and the oxidative stability of the catalyst. [Copyright &y& Elsevier]

Highlights: [•] A carbamide-assistant hydrothermal process was used for surface coating. [•] Homogeneous Al2O3 coating layer was grown on LiMn1.5Ni0.5O4 particles. [•] The structure and morphology of the substrate material were not destroyed. [•] The degradation of LiMn1.5Ni0.5O4 was suppressed by this treatment. [ABSTRACT FROM AUTHOR]

Mo, Co co-doped NiS/Ni 3 S 4 with high activity, low onset potential, fast kinetics, more active sites, excellent intrinsic catalytic activity and stability demonstrates excellent catalytic activity toward alkaline urea electrolysis. [Display omitted] • Mo, Co co-doped NiS/Ni 3 S 4 heterojunction with 3D flower-like shape assembled by 2D ultrathin nanosheets are successfully prepared. • The amount of heterointerfaces and the electronic interaction are simultaneously modified by adjusting experimental parameters. • Mo, Co co-doped NiS/Ni 3 S 4 catalysts exhibit rich exposed active sites and facilitated electron transportation. • The assembled direct urea hydrogen peroxide fuel cell (DUHPFC) employing Mo 0.05 ,Co-NSH has an open-circle voltage (OCV) of 0.86 V and a maximum power density (P max) of 5.96 mW cm−2. Electrocatalysts exhibiting impressive catalytic capability and strong stability for urea oxidation reaction (UOR) are highly desired for direct urea fuel cells (DUFCs). Herein, a series of flower-like Mo, Co co-doped NiS/Ni 3 S 4 heterostructure (Mo, Co-NSH) are controllable synthesized by a one-step hydrothermal method and utilized as catalysts for UOR. Taking advantages of massive heterojunctions, tunable electronic configuration and hierarchical flower-like topological structure together, the optimized component demonstrates advanced UOR performance compared to pure NiS/Ni 3 S 4 and mono Co/Mo element doped NiS/Ni 3 S 4 , it delivers 147.1 mA cm−2 at 1.6 V vs. RHE and works for more than 18 h without decay. The assembly direct urea hydrogen peroxide fuel cell (DUHPFC) with Mo 0.05 , Co-NSH catalyst has an open-circuit voltage of 0.86 V and a maximum power density of 5.96 mW cm−2 at 27 °C. The work provides a promising avenue for exploiting efficient electrocatalysts on both multi-metal doping and heterojunction engineering for electrochemical energy conversion and sewage treatment applications. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effect of natural products used empirically for dental bleaching on the color alteration (ΔE00), whitening index for dentistry (WID), surface gloss and microhardness of dental enamel. For this study 70 fragments of bovine teeth (6x6x2mm) were obtained and separated in five groups (n=14), according to the product used for the treatments: G1 (conventional toothpaste), G2 (charcoal), G3 (curcumin), G4 (banana peel) and G5 (16% carbamide peroxide gel). Initial color (Easyshade, VITA), surface gloss (Micro-Gloss 45, BYK Gardner), and microhardness (Micro Hardness Tester HMV-2, Shimadzu) readings were performed. For G1 to G4, treatments were performed using a simulated toothbrushing machine where the samples were brushed for 560 cycles (14 day of brushing T1) and 1200 cycles total (simulating 30 days of brushing T2). New readings were obtained after T1 and T2. For the G5 group, the treatment with carbamide peroxide gel were submitted on the fragments during 4 hours/day for 14 days, and then final readings were obtained. Regarding EΔ00, only G5 showed difference from other groups (p>0.5). For the WID analysis, after 14 days G3 (curcumin) showed lower whitening efficacy (p>0.5), and after 30 days there was no difference between groups (p<0.5) except for the carbamide peroxide group. Banana peel, curcumin and carbamide peroxide caused a decrease in the enamel gloss values after T1, different (p>0.5) from the charcoal and toothpaste groups. Charcoal resulted in the higher gloss values in T2, different (p>0.5) from all groups, except toothpaste. Carbamide peroxide showed the lower microhardness values, similar (p<0.5) to the banana peel and curcumin groups. Considering the results found, it can be concluded that natural products that have been used for dental bleaching purposes did not present effectiveness on the enamel color alteration. Furthermore, banana peel and curcumin caused a decrease in microhardness similar to carbamide peroxide. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to investigate the effect of home bleaching agents on the color and translucency of resin composites. Methods: Thirty disc shaped specimens (1 mm thick) were fabricated from each resin composite (Reflexions, Grandio, Gradia Direct, Clearfil Majesty Esthetic, Ceram-X Mono) and divided into 3 subgroups as carbamide peroxide (CP, Opalescence 10% PF), hydrogen peroxide (HP, 10% Opalescence Treswhite Supreme) and control group (n = 10). Baseline CIE L*a*b* color coordinates were measured with spectrophotometer and translucency parameters (TP) were calculated. CP and HP groups were treated with bleaching agents according to manufacturers' instructions and control group was stored in distilled water (DW) for 14 days. Color and translucency measurements were repeated and color differences were calculated,ΔDE values > 3.3 were considered as clinically unacceptable. Results: Clinically unacceptable color change was detected for all resin composites exposed to bleaching agents and there was significant color difference between the control group and bleached specimens (P < 0.05). However no significant color difference was found between CP and HP groups. Intragroup comparison revealed that Ceram-X Mono showed the highest color change but there was no significant difference among the other tested materials for both CP and HP groups. Intergroup comparison of TP values of CP, HP and control groups at the end of 14th day revealed that there was no statistical significant translucency difference among the groups. Conclusions: Application of CP and HP resulted in clinically unacceptable color change for all resin composites. Translucencies of the resin composites were not affected by bleaching procedure. Clinical significance: The results of this in vitro study suggest that patients should be informed regarding a potential color change of existing resin composite restorations with the use of home bleaching agents. [ABSTRACT FROM AUTHOR]

Objectives: This randomised controlled clinical trial assessed the efficacy of color change and sensitivity after in surgery whitening with and without light activation. Methods: Twenty two patients were randomly assigned to one of two different groups: Group A - in-surgery bleaching with light activated 25% hydrogen peroxide gel followed by 2 weeks at home, night time bleaching with 10% carbamide peroxide gel in a customised bleaching tray. Group B - in-surgery bleaching with 25% hydrogen peroxide without light activation followed by 2 weeks at home, night time bleaching with 10% carbamide peroxide gel in a customised bleaching tray. The efficacy of tooth whitening was assessed by determining the color change associated with the six maxillary anterior teeth. Sensitivity was self-assessed with the use of a visual analogue scale (VAS). Results: Overall, there was no significant difference in shade change between the two groups immediately after the in surgery whitening phase, and at one or two weeks post in surgery treatment. With regard to sensitivity immediately following the in surgery whitening participants in Group B reported a significantly higher level of sensitivity in comparison to Group A ( p = 0.03). Conclusions: There was no significant difference between the shade improvements achieved by the two whitening protocols tested throughout the 2-week period of the study ( p > 0.05). There was no statistical significant difference in sensitivity at the one and two week review periods, however, immediately after treatment participants in Group B reported a significantly higher level of sensitivity than participants in Group A ( p = 0.03). [ABSTRACT FROM AUTHOR]

Abstract: Highly porous sinter-hardenable Cr–Si–Ni–Mo based steel foam for automotive applications was produced by space holder method. Steel powders were mixed with binder (polyvinylalcohol) and space holder (carbamide), and compacted. Carbamide in the green compacts was removed by water leaching at room temperature. The green specimens were then sintered at temperatures between 1100°C and 1250°C for sintering times of 15, 30 and 45min. In addition, the steel foams were sinter-hardened to enhance mechanical properties. Sinter-hardening combines sintering and heat treatment in one step by increasing the post-sintering cooling rate. This reduces the cost of operation and makes powder metallurgy more competitive. Effects of sinter-hardening process parameters on compressive strength, Young’s modulus, hardness and energy absorption of the steel foams were investigated. [Copyright &y& Elsevier]

Abstract: The aim of this study was to investigate the influence of molar mass of thiolated polymers (thiomers) on their in situ gelling properties. Chitosan–thioglycolic acid (chitosan–TGA) and pectin–cysteine (pectin–Cys) of increasing molar mass were chosen to produce in situ gels in combination with carbamide peroxide. Low molar mass chitosan (∼2kDa) was prepared by oxidative degradation with NaNO2, whereas pectin was depolymerized by heat treatment. Thiomers, displaying 1271–1616μmol (chitosan–TGA) and 305–403μmol (pectin–Cys) free thiol groups per gram polymer, were synthesized via amide bond formation mediated by a carbodiimide. The results showed that a reduction of molar mass combined with increased concentrations of both cationic chitosan–TGA and anionic pectin–Cys leads to higher final viscosities and to a higher relative increase in viscosity within 60min and 180min, respectively. Using this method, the dynamic viscosity of a very low molar mass chitosan–TGA (∼2kDa) could be increased 100,000-fold within 60min and 390,000-fold within 180min. In view of these in situ gelling properties carbohydrate thiomers might be useful for various pharmaceutical applications such as vehicle for drug delivery or as wound dressing material. [Copyright &y& Elsevier]

Summary: Objectives: This double-blind randomized clinical trial aimed to evaluate the whitening effect of two at-home tooth bleaching agents and the effect of dietary habits after 2 years. The patients’ view about bleaching longevity was also investigated. Methods: Ninety-two subjects with mean shade of C1 or darker for the six maxillary anterior teeth were randomized into two groups (n =46) according to the carbamide peroxide (CP) concentration: 10% (CP10) or 16% (CP16). The treatment was performed using the whitening agent in a tray for 2h/day during 3 weeks. Shade evaluations were done with a shade guide and a spectrophotometer at baseline, 1-month, 6-month, 1-year and 2-year post-bleaching. Results: Eighty-one (88%) of the original 92 subjects enrolled in the study were recalled at 2-year follow-up and, the tooth shade remained significantly lighter than at baseline, in both treatment groups, considering the tooth shade median values (p <0.001) or the color parameters: L*a* (p <0.001) for CP10 and, L*b* for CP16 group (p <0.001). Subjects from CP10 and CP16 reported a consumption of beverage and food stains as high as at 6-month and 1-year recalls and, more than 66% of the participants from each group reported a tooth shade relapse from mild to moderate (p =0.6). Significance: At 2-year post-bleaching, tooth shade remained lighter than at baseline for both CP concentrations tested. Tooth shade relapse associated to increasing of a* and b* color parameters were observed for both groups when compared to the end of the treatment (CEP # 37/05). [ABSTRACT FROM AUTHOR]

[Display omitted] • Researched urea hydrogen peroxide (∼30 GPa) by Raman spectrum and ADXRD. • The phase transition occurs at 2.5 GPa. • The ADXRD was performed for it, confirmed that was an irreversible transition. • Hydrogen bonding may stabilize organic crystals at extreme conditions. • Provide a new strategy for the role of hydrogen bond in the adduct system. The effect of high-pressure on the crystal structure of urea hydrogen peroxide has been investigated to 30 GPa. Through in-situ Raman scattering and ADXRD measurements, a first-order phase transition is concluded at 2.5GPa, and the new phase is indexed to a triclinic phase using Rietveld refinement method. Further increase in pressure up to 30 GPa does not show any structural phase transition. From the Raman analysis, the irreversible phase transition should be correlated with the twist structure of urea in the adduct of urea and hydrogen peroxide as a result of the cooperation and competition of inter-molecular hydrogen bonds. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: This double blind randomized clinical trial evaluated the longevity of the whitening effect (6-month follow-up) of two carbamide peroxide concentrations used in at-home vital bleaching. Methods: Ninety-two volunteers with shade mean C1 or darker for the six maxillary anterior teeth were randomized into two balanced groups (n =46) according to bleaching agent concentration: 10% (CP10) or 16% (CP16) carbamide peroxide. Patients were instructed to use the whitening agent in a tray for 2h/day during 3 weeks. Shade evaluations were done with a value-oriented shade guide, and a spectrophotometer at baseline, and at 1-week and 6-month post-bleaching. Volunteers for both treatment groups had to answer questions related to dietary and oral hygiene behavior. Results: At 6-month recall, tooth shade remained significantly lighter than at baseline, in both treatment groups, considering the color parameters: ΔL*, Δa*, Δb*, ΔE* (p <0.0001) or the tooth shade median values (p <0.001). Additionally, shade median relapse at 6-month follow-up was not statistically different between CP10 and CP16 groups using the spectrophotometer (p =0.1) or the visual matching (p =0.7) analyses. Overall, subjects from CP10 and CP16 reported high consumption of beverage and food stains, which was not different between groups (p =0.5). Conclusions: The whitening effect remained similar 6-month after the bleaching treatment for both carbamide peroxide concentrations tested. Additionally, the high consumption of staining beverages and foods reported by patients had no influence in the whitening effect longevity at 6-month. [Copyright &y& Elsevier]

Abstract: Purpose: The aim of this study was to comparatively investigate the effect of antioxidant treatment and delayed bonding after bleaching with carbamide peroxide on the shear bond strength (SBS) of a luting resin to enamel. Materials and methods: Forty flat enamel surfaces were prepared from freshly extracted human molars using a low speed diamond saw, then divided into three bleaching groups (n =10/group) and a control group (n =10). Group 1 consisted of specimens bonded immediately after bleaching. Group 2 specimens were treated with an antioxidant agent, 10% sodium ascorbate, while Group 3 specimens were immersed in artificial saliva for 1 week after bleaching. Specimens in Group 4 were not bleached, but immersed in artificial saliva for 1 week before bonding. Forty ceramic blocks (Empress 2, Ivoclar) were prepared and luted to teeth using a dual-curing resin cement (Variolink II, Ivoclar). The specimens were thermocycled and the SBS tests were performed using a universal testing machine (crosshead speed: 0.5mm/min). Fracture analysis of the bonded surfaces was done using a scanning electron microscope. Statistical analysis was carried out by Kruskall–Wallis and Mann–Whitney U-tests. Results: While the samples that were immediately bonded after bleaching (Group I) demonstrated significantly lower shear bond strengths and 10% sodium ascorbate group (Group II) demonstrated significantly higher bond strengths than control group samples (p <0.05), no significant differences were found among delayed bonded group and control group (p >0.05). Conclusion: Using sodium ascorbate with a concentration of 10% may be reliable for reversing the compromised bond strength. [Copyright &y& Elsevier]

Abstract: Objectives: To evaluate the effects of fluoridated bleaching agents and post-bleaching fluoridation treatment on the whitening efficiency and microhardness of bovine enamel. Methods: Twenty five freshly extracted bovine incisors were cut into halves, embedded and then divided into the following five groups: Group 1, untreated controls; Group 2, treatment with 10% carbamide peroxide (CP) bleaching agent; Group 3, treatment with 10% CP followed by a 0.9% sodium fluoride gel application, Group 4, treatment with 10% CP containing 0.11% fluoride; Group 5, treatment with an experimental bleaching agent consisting of 10% CP and 0.37% fluoride. Groups 2–5 were treated 8h per day for 14 days then immersed in saliva for 2 weeks. Enamel morphology changes were evaluated under SEM on Day 14. Changes in enamel color and microhardness were evaluated on Days 7 and 14, and compared with the baseline data. Additionally, microhardness was determined on post-bleaching Days 21 and 28. Results: After 2 weeks, an erosion pattern was noted on the specimens in Groups 2 and 3. Groups 4 and 5 showed a milder demineralized pattern. All the bleached enamel specimens revealed increased whiteness and overall color value. Groups 2 and 3 showed significantly decreased enamel microhardness compared to their baseline data. The specimens treated with fluoridated bleaching agents showed relatively less reduction in enamel microhardness than those treated with nonfluoridated agents during the bleaching treatment. Conclusions: The fluoridated bleaching agents produced less demineralization of surface morphology and microhardness. The addition of fluoride did not impede the whitening effect. [Copyright &y& Elsevier]