El Niño, Sea Surface Temperature Anomaly and Coral Bleaching in the South Atlantic: A Chain of Events Modeled With a Bayesian Approach

NASA Astrophysics Data System (ADS)

Lisboa, D. S.; Kikuchi, R. K. P.; Leão, Zelinda M. A. N.

2018-04-01

Coral bleaching represents one of the main climate-change related threats to reef ecosystems. This research represents a methodological alternative for modeling this phenomenon, focused on assessing uncertainties and complexities with a low number of observations. To develop this model, intermittent reef monitoring data from the largest reef complex in the South Atlantic collected over nine summers between 2000 and 2014 were used with remote sensing data to construct and train a bleaching seasonal prediction model. The Bayesian approach was used to construct the network as it is suitable for hierarchically organizing local thermal variables and combining them with El Niño indicators from the preceding winter to generate accurate bleaching predictions for the coming season. Network count information from six environmental indicators was used to calculate the probability of bleaching, which is mainly influenced by the combined information of two thermal indices; one thermal index is designed to track short period anomalies in the early summer that are capable of triggering bleaching (SST of five consecutive days), and the other index is responsible for tracking the accumulation of thermal stress over time, an index called degree heating trimester (DHT). In addition to developing the network, this study conducted the three tests of applicability proposed for model: 1- Perform the forecast of coral bleaching for the summer of 2016; 2- Investigate the role of turbidity during the bleaching episodes; and 3- Use the model information to identify areas with a lower predisposition to bleaching events.

Non-inferiority of pulsed xenon UV light versus bleach for reducing environmental Clostridium difficile contamination on high-touch surfaces in Clostridium difficile infection isolation rooms

PubMed Central

Ghantoji, Shashank S.; Stibich, Mark; Stachowiak, Julie; Cantu, Sherry; Adachi, Javier A.; Raad, Issam I.

2015-01-01

The standard for Clostridium difficile surface decontamination is bleach solution at a concentration of 10 % of sodium hypochlorite. Pulsed xenon UV light (PX-UV) is a means of quickly producing germicidal UV that has been shown to be effective in reducing environmental contamination by C. difficile spores. The purpose of this study was to investigate whether PX-UV was equivalent to bleach for decontamination of surfaces in C. difficile infection isolation rooms. High-touch surfaces in rooms previously occupied by C. difficile infected patients were sampled after discharge but before and after cleaning using either bleach or non-bleach cleaning followed by 15 min of PX-UV treatment. A total of 298 samples were collected by using a moistened wipe specifically designed for the removal of spores. Prior to disinfection, the mean contamination level was 2.39 c.f.u. for bleach rooms and 22.97 for UV rooms. After disinfection, the mean level of contamination for bleach was 0.71 c.f.u. (P = 0.1380), and 1.19 c.f.u. (P = 0.0017) for PX-UV disinfected rooms. The difference in final contamination levels between the two cleaning protocols was not significantly different (P = 0.9838). PX-UV disinfection appears to be at least equivalent to bleach in the ability to decrease environmental contamination with C. difficile spores. Larger studies are needed to validate this conclusion. PMID:25627208

Laser Imaging Polarimetry of Nacre.

PubMed

Jones, Joshua A; Metzler, Rebecca A; D'Addario, Anthony J; Burgess, Carrie; Regan, Brian; Spano, Samantha; Cvarch, Ben A; Galvez, Enrique J

2018-03-25

Nacre is a complex biomaterial made of aragonite-tablet bricks and organic mortar that is considerably resilient against breakage. Nacre has been studied with a wide range of laboratory techniques, leading to understanding key fundamentals, and informing the creation of bio-inspired materials. In this article we present an optical polarimetric technique to investigate nacre, taking advantage of the translucence and birefringence of its micro-components. We focus our study on three classes of mollusks that have nacreous shells: bivalve (Pinctada fucata), gastropod (Haliotis asisina and Haliotis rufescens) and cephalopod (Nautilus pompilius). We sent polarized light from a laser through thin samples of nacre and did imaging polarimetry of the transmitted light. We observed clear distinctions between the structures of bivalve and gastropod, due to the spatial variation of their birefringence. The patterns for cephalopod were more similar to bivalve than gastropod. Bleaching of the samples disrupted the transmitted light. Subsequent refilling of the bivalve and gastropod nacre samples with oil produced optical patterns similar to those of unbleached samples. In cephalopod samples we found that bleaching produced irreversible changes in the optical pattern. This article is protected by copyright. All rights reserved.

Mechanistic insights into the bleaching of melanin by alkaline hydrogen peroxide.

PubMed

Smith, R A W; Garrett, B; Naqvi, K R; Fülöp, A; Godfrey, S P; Marsh, J M; Chechik, V

2017-07-01

This work aims to determine the roles of reactive oxygen species HO∙ and HO 2 - in the bleaching of melanins by alkaline hydrogen peroxide. Experiments using melanosomes isolated from human hair indicated that the HO∙ radical generated in the outside solution does not contribute significantly to bleaching. However, studies using soluble Sepia melanin demonstrated that both HO 2 - and HO∙ will individually bleach melanin. Additionally, when both oxidants are present, bleaching is increased dramatically in both rate and extent. Careful experimental design enabled the separation of the roles and effects of these key reactive species, HO∙ and HO 2 - . Rationalisation of the results presented, and review of previous literature, allowed the postulation of a simplified general scheme whereby the strong oxidant HO∙ is able to pre-oxidise melanin units to o-quinones enabling more facile ring opening by the more nucleophilic HO 2 - . In this manner the efficiency of the roles of both species is maximised. Copyright © 2017 Elsevier Inc. All rights reserved.

Optimization of Bleaching Parameters in Refining Process of Kenaf Seed Oil with a Central Composite Design Model.

PubMed

Chew, Sook Chin; Tan, Chin Ping; Nyam, Kar Lin

2017-07-01

Kenaf seed oil has been suggested to be used as nutritious edible oil due to its unique fatty acid composition and nutritional value. The objective of this study was to optimize the bleaching parameters of the chemical refining process for kenaf seed oil, namely concentration of bleaching earth (0.5 to 2.5% w/w), temperature (30 to 110 °C) and time (5 to 65 min) based on the responses of total oxidation value (TOTOX) and color reduction using response surface methodology. The results indicated that the corresponding response surface models were highly statistical significant (P < 0.0001) and sufficient to describe and predict TOTOX value and color reduction with R 2 of 0.9713 and 0.9388, respectively. The optimal parameters in the bleaching stage of kenaf seed oil were: 1.5% w/w of the concentration of bleaching earth, temperature of 70 °C, and time of 40 min. These optimum parameters produced bleached kenaf seed oil with TOTOX value of 8.09 and color reduction of 32.95%. There were no significant differences (P > 0.05) between experimental and predicted values, indicating the adequacy of the fitted models. © 2017 Institute of Food Technologists®.

The Chemistry and Perception of Fluorescent White Textile Materials

NASA Astrophysics Data System (ADS)

Xu, Changhai

Cationic bleach activators (CBA) are precursors to perhydroxyl compounds that, when activated, have higher oxidation potential and potentially improved bleaching performance compared to common oxidizing agents such as hydrogen peroxide. CBAs were first reported in 1997 by Proctor & Gamble Co., and have been further developed at North Carolina State University. To date, an effective low temperature bleaching system has not been developed that offers sufficient economic improvement over existing bleaching systems. The primary purpose of this research was to develop new methods and understand key variables required for achieving enhanced whiteness of textile materials using bleach activators with or without the presence of fluorescence. A new optimized low temperature bleaching system using novel lactam-based bleach activators was developed and the effect of UV content of light sources on the whiteness of fluorescent white textile materials was evaluated. A novel class of bleach activators was synthesized by introducing benzoylcaprolactam group into a stilbene system shown as follows:* While solubility, purification and hydrolytic stability of the compounds were problematic, a new approach to low pH (pH 7-9) and low temperature (50-70°C) bleaching was found using a butyrolactam-based cationic bleach activator, N-[4-(triethylammonio methyl)benzoyl]-butyrolactam chloride (TBBC), using a central composite design (CCD) of experiment. The CCD bleaching experiments showed that cationic bleach activators are less effective with high concentrations of hydrogen peroxide in high alkaline solutions. Also a 2FI model predicted the optimized bleaching performance on 100% cotton at near neutral pH and temperatures around 50°C, in which the dosage of TBBC is the most important factor affecting the bleaching performance. This prediction was validated experimentally during bleaching of bamboo and cotton fibers. In addition, this study confirmed the hypothesis that cationic bleach activators have inherent substantivity to cellulosic fibers and that the substantivity enhances bleach effectiveness. This cationic activated bleach system was effective for cotton bleaching and the bleaching performance is superior to that of conventional peroxide bleaching. TBBC was also applied to bamboo cellulosic fibers, which exhibit excessive strength loss during conventional hot bleaching. Under optimized conditions of 5 g/L TBBC, 50°C, 30 min and pH 7.0, TBBC-based bleaching of bamboo fibers produced CIE Whiteness Index (CIE WI) values of 58.20 compared to untreated bamboo which had CIE WI values of 10.77. Hence, the TBBC bleach activator method is effective at bleaching bamboo fibers. Besides chemical bleaching, the fluorescent whitening was another approach to increase the whiteness of materials. Since the whiteness of fluorescent white materials is produced by absorbing UV light and emitting visible blue light, the UV content of light sources has a significant effect on the perception of whiteness. This research addresses the common light sources used in color matching booths. The pilot data is collected by measuring spectral radiance and spectral irradiance, which is used for analysis of the UV effect on the whiteness of fluorescent white materials. The whitening performance of a fluorescent brightening agent (FBA) is dependent on the energy and intensity of the incident UV light. No data have been reported in the open literature that shows the UV emission of standard lamps used in viewing booths. Indeed, standards pertaining to lighting do not require or recommend the standardization of the UV content in any lamps. Hence, the spectroradiometric quantification of UV emission of a series of standard viewing booths is a requirement for establishment of a methodology to determine the effect of radiometric variability in standard sources on visual perception of fluorescent white materials. The radiance measurement data collected from measuring the radiance of light sources (including daylight simulation, incandescent, horizon daylight, cool white fluorescence, and Ultralume 30) in a SpectraLight III color viewing booth and the irradiance of these light sources over a PTFE diffuse reflectance standard, AATCC textile UV calibration standard and some fluorescent whitened fabric samples showed the inadequacy of UV content of these light sources in the SpectraLight III. *Please refer to dissertation for diagram.

Effects of Temperature and pCO2 on Population Regulation of Symbiodinium spp. in a Tropical Reef Coral.

PubMed

Baghdasarian, Garen; Osberg, Andrew; Mihora, Danielle; Putnam, Hollie; Gates, Ruth D; Edmunds, Peter J

2017-04-01

This study tested the bleaching response of the Pacific coral Seriatopora caliendrum to short-term exposure to high temperature and elevated partial pressure of carbon dioxide (pCO 2 ). Juvenile colonies collected from Nanwan Bay, Taiwan, were used in a factorial experimental design in which 2 temperatures (∼27.6 °C and ∼30.4 °C) and 2 pCO 2 values (∼47.2 Pa and ∼90.7 Pa) were crossed to evaluate, over 12 days, the effects on the densities and physiology of the symbiotic dinoflagellates (Symbiodinium) in the corals. Thermal bleaching, as defined by a reduction of Symbiodinium densities at high temperature, was unaffected by high pCO 2 . The division, or mitotic index (MI), of Symbiodinium remaining in thermally bleached corals was about 35% lower than in control colonies, but they contained about 53% more chlorophyll. Bleaching was highly variable among colonies, but the differences were unrelated to MI or pigment content of Symbiodinium remaining in the coral host. At the end of the study, all of the corals contained clade C Symbiodinium (either C1d or C15), and the genetic variation of symbionts did not account for among-colony bleaching differences. These results showed that high temperature causes coral bleaching independent of pCO 2 , and underscores the potential role of the coral host in driving intraspecific variation in coral bleaching.

In-office bleaching efficacy on stain removal from CAD/CAM and direct resin composite materials.

PubMed

Alharbi, Amal; Ardu, Stefano; Bortolotto, Tissiana; Krejci, Ivo

2018-01-01

To evaluate the efficacy of in-office bleaching on stain removal from stained resin composite and ceramic computer-assisted design/computer-assisted manufacturing (CAD/CAM) blocks and direct resin composites. Forty disk-shaped samples were fabricated from each of nine materials: six CAD/CAM (VITABLOCS Mark II, Paradigm MZ100, Exp Vita Hybrid Ceramic, VITA ENAMIC, Exp Kerr, and LAVA Ultimate) and three direct resin composites (Filtek Supreme, Venus Diamond, and Filtek Silorane). Samples were randomly divided into five groups (n = 8), each stained with a particular staining solution. Using a calibrated spectrophotometer and a black background, L*a*b* values were assessed before and after 120 days of staining. Samples were subjected to in-office bleaching using 40% hydrogen peroxide gel for one hour. At subsequent assessment, color change (ΔE) was calculated as the difference between L*a*b* values. Both ANOVA and the Duncan test were used to identify differences between groups (α = 0.05). Bleaching resulted in significant differences in ΔE values for all materials (P < .001). Bleaching efficacy was highly influenced by material composition and staining solution. Residual color values after bleaching for ceramic and hybrid ceramics ranged from -0.49 to 2.35, within the clinically acceptable maximum of 3.3. Values after bleaching for resin-based CAD/CAM ranged from -0.7 to 7.08 while direct resin composites values ranged from -1.47 to 25.13. Coffee left the greatest residual color on all materials. Based on material nature, 40% hydrogen peroxide bleaching can remove staining. The new resin-based CAD/CAM blocks showed promising results in terms of color stability. Bleaching using 40% hydrogen peroxide can be an effective method to remove stains from dental restorations. In this way, restoration replacement as a result of discoloration may no longer be necessary. © 2017 Wiley Periodicals, Inc.

Patterns of gene expression in a scleractinian coral undergoing natural bleaching.

PubMed

Seneca, Francois O; Forêt, Sylvain; Ball, Eldon E; Smith-Keune, Carolyn; Miller, David J; van Oppen, Madeleine J H

2010-10-01

Coral bleaching is a major threat to coral reefs worldwide and is predicted to intensify with increasing global temperature. This study represents the first investigation of gene expression in an Indo-Pacific coral species undergoing natural bleaching which involved the loss of algal symbionts. Quantitative real-time polymerase chain reaction experiments were conducted to select and evaluate coral internal control genes (ICGs), and to investigate selected coral genes of interest (GOIs) for changes in gene expression in nine colonies of the scleractinian coral Acropora millepora undergoing bleaching at Magnetic Island, Great Barrier Reef, Australia. Among the six ICGs tested, glyceraldehyde 3-phosphate dehydrogenase and the ribosomal protein genes S7 and L9 exhibited the most constant expression levels between samples from healthy-looking colonies and samples from the same colonies when severely bleached a year later. These ICGs were therefore utilised for normalisation of expression data for seven selected GOIs. Of the seven GOIs, homologues of catalase, C-type lectin and chromoprotein genes were significantly up-regulated as a result of bleaching by factors of 1.81, 1.46 and 1.61 (linear mixed models analysis of variance, P < 0.05), respectively. We present these genes as potential coral bleaching response genes. In contrast, three genes, including one putative ICG, showed highly variable levels of expression between coral colonies. Potential variation in microhabitat, gene function unrelated to the stress response and individualised stress responses may influence such differences between colonies and need to be better understood when designing and interpreting future studies of gene expression in natural coral populations.

Efficacy of Detergent and Water Versus Bleach for the Disinfection of Direct Contact Ophthalmic Lenses

PubMed Central

Abbey, Ashkan M.; Gregori, Ninel Z.; Surapaneni, Krishna; Miller, Darlene

2014-01-01

Purpose While manufacturers recommend cleaning ophthalmic lenses with detergent and water and then a specific disinfectant, disinfectants are rarely used in ophthalmic practices. The aim of this pilot study was to evaluate the efficacy of detergent and water versus bleach, a recommended disinfectant, to eliminate common ocular bacteria and viruses from ophthalmic lenses. Methods Three bacterial strains (Staphylococcus epidermidis, Corynebacterium straitum, and methicillin-resistant Staphylococcus aureus (MRSA) and two viral strains (adenovirus and herpes simplex virus (HSV) type-1) were individually inoculated to 20 gonioscopy and laser lenses. Lenses were washed with detergent and water and then disinfected with 10% bleach. All lenses were cultured after inoculation, after detergent and water, and after the bleach. Bacterial cultures in thioglycollate broth were observed for 3 weeks and viral cultures for 2 weeks. The presence of viruses was also detected by multiplex polymerase chain reaction (PCR). Results All 20 lenses inoculated with Staphylococcus epidermidis, Corynebacterium straitum, adenovirus, and HSV-1 showed growth after inoculation, but no growth after detergent/water and after the bleach. All lenses showed positive HSV and adenovirus PCR after inoculation and negative PCR after detergent/water and after bleach. All MRSA contaminated lenses showed growth after inoculation and no growth after detergent and water. However, one lens showed positive growth after bleach. Conclusions Cleaning with detergent and water appeared to effectively eliminate bacteria and viruses from the surface of contaminated ophthalmic lenses. Further studies are warranted to design practical disinfection protocols that minimize lens damage. PMID:24747806

Effect of ultrasonic pre-treatment of thermomechanical pulp on hydrogen peroxide bleaching

NASA Astrophysics Data System (ADS)

Loranger, E.; Charles, A.; Daneault, C.

2012-12-01

Ultrasound pre-treatments of softwood TMP had been carried to evaluate its impact on the efficiency of hydrogen peroxide bleaching. The trials were performed after a factorial design of experiment using frequency, power and time as variables. The experiments were conducted in an ultrasonic bath and then bleached with hydrogen peroxide. Measurements such as brightness, L*A*B* color system coordinate, residual hydrogen peroxide and metal content were evaluated on bleached pulp. The results indicate that the effect of ultrasonic treatment on brightness was dependent on the ultrasound frequency used; the brightness increased slightly at 68 kHz and decreased at 40 and 170 kHz. These results were correlated to the ultrasound effect on the generation of transition metals (copper, iron and manganese) which are responsible for catalytic decomposition of hydrogen peroxide. The influence of metal interference was minimized by using a chelating agent such as diethylene triamine pentaacetic acid (DTPA). With the results obtained in this study we have identified a set of option conditions, e.g. 1000 W, 40 kHz, 1.5 % consistency and 0.2% addition of DTPA prior to the bleaching stage (after ultrasonic pre-treatment) who improve brightness by 2.5 %ISO.

Mill Designed Bio bleaching Technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Institute of Paper Science Technology

2004-01-30

A key finding of this research program was that Laccase Mediator Systems (LMS) treatments on high-kappa kraft could be successfully accomplished providing substantial delignification (i.e., > 50%) without detrimental impact on viscosity and significantly improved yield properties. The efficiency of the LMS was evident since most of the lignin from the pulp was removed in less than one hour at 45 degrees C. Of the mediators investigated, violuric acid was the most effective vis-a-vis delignification. A comparative study between oxygen delignification and violuric acid revealed that under relatively mild conditions, a single or a double LMS{sub VA} treatment is comparablemore » to a single or a double O stage. Of great notability was the retention of end viscosity of LMS{sub VA} treated pulps with respect to the end viscosity of oxygen treated pulps. These pulps could then be bleached to full brightness values employing conventional ECF bleaching technologies and the final pulp physical properties were equal and/or better than those bleached in a conventional ECF manner employing an aggressively O or OO stage initially. Spectral analyses of residual lignins isolated after LMS treated high-kappa kraft pulps revealed that similar to HBT, VA and NHA preferentially attack phenolic lignin moieties. In addition, a substantial decrease in aliphatic hydroxyl groups was also noted, suggesting side chain oxidation. In all cases, an increase in carboxylic acid was observed. Of notable importance was the different selectivity of NHA, VA and HBT towards lignin functional groups, despite the common N-OH moiety. C-5 condensed phenolic lignin groups were overall resistant to an LMS{sub NHA, HBT} treatments but to a lesser extent to an LMS{sub VA}. The inactiveness of these condensed lignin moieties was not observed when low-kappa kraft pulps were biobleached, suggesting that the LMS chemistry is influenced by the extent of delignification. We have also demonstrated that the current generation of laccase has a broad spectrum of operating parameters. Nonetheless, the development of future genetically engineered laccases with enhanced temperature, pH and redox potentials will dramatically improve the overall process. A second challenge for LMS bleaching technologies is the need to develop effective, catalytic mediators. From the literature we already know this is feasible since ABTS and some inorganic mediators are catalytic. Unfortunately, the mediators that exhibit catalytic properties do not exhibit significant delignification properties and this is a challenge for future research studies. Potential short-term mill application of laccase has been recently reported by Felby132 and Chandra133 as they have demonstrated that the physical properties of linerboard can be improved when exposed to laccase without a chemical mediator. In addition, xxx has shown that the addition of laccase to the whitewater of the paper machine has several benefits for the removal of colloidal materials. Finally, this research program has presented important features on the delignification chemistry of LMS{sub NHA} and LMS{sub VA} that, in the opinion of the author, are momentous contributions to the overall LMS chemistry/biochemistry knowledge base which will continue to have future benefits.« less

Response surface modeling of acid activation of raw diatomite using in sunflower oil bleaching by: Box-Behnken experimental design.

PubMed

Larouci, M; Safa, M; Meddah, B; Aoues, A; Sonnet, P

2015-03-01

The optimum conditions for acid activation of diatomite for maximizing bleaching efficiency of the diatomite in sun flower oil treatment were studied. Box-Behnken experimental design combining with response surface modeling (RSM) and quadratic programming (QP) was employed to obtain the optimum conditions of three independent variables (acid concentration, activation time and solid to liquid) for acid activation of diatomite. The significance of independent variables and their interactions were tested by means of the analysis of variance (ANOVA) with 95 % confidence limits (α = 0.05). The optimum values of the selected variables were obtained by solving the quadratic regression model, as well as by analyzing the response surface contour plots. The experimental conditions at this global point were determined to be acid concentration = 8.963 N, activation time = 11.9878 h, and solid to liquid ratio = 221.2113 g/l, the corresponding bleaching efficiency was found to be about 99 %.

Characterization of the absorbance bleaching in AllnAs/AlGaInAs multiple-quantum wells for semiconductor saturable absorbers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wanke, Michael Clement; Cederberg, Jeffrey George; Alliman, Darrell L.

2010-05-01

Semiconductor saturable absorbers (SESAs) introduce loss into a solid-state laser cavity until the cavity field bleaches the absorber producing a high-energy pulse. Multiple quantum wells (MQWs) of AlGaInAs grown lattice-matched to InP have characteristics that make them attractive for SESAs. The band gap can be tuned around the target wavelength, 1064 nm, and the large conduction band offset relative to the AlInAs barrier material helps reduces the saturation fluence, and transparent substrate reduces nonsaturable losses. We have characterized the lifetime of the bleaching process, the modulation depth, the nonsaturable losses, and the saturation fluence associated with SESAs. We compare differentmore » growth conditions and structure designs. These parameters give insight into the quality of the epitaxy and effect structure design has on SESA performance in a laser cavity. AlGaInAs MQWs were grown by MOVPE using a Veeco D125 machine using methyl-substituted metal-organics and hydride sources at a growth temperature of 660 C at a pressure of 60 Torr. A single period of the basic SESA design consists of approximately 130 to 140 nm of AlInAs barrier followed by two AlGaInAs quantum wells separated by 10 nm AlInAs. This design places the QWs near the nodes of the 1064-nm laser cavity standing wave. Structures consisting of 10-, 20-, and 30-periods were grown and evaluated. The SESAs were measured at 1064 nm using an optical pump-probe technique. The absorbance bleaching lifetime varies from 160 to 300 nsec. The nonsaturable loss was as much as 50% for structures grown on n-type, sulfur-doped InP substrates, but was reduced to 16% when compensated, Fe-doped InP substrates were used. The modulation depth of the SESAs increased linearly from 9% to 30% with the number of periods. We are currently investigating how detuning the QW transition energy impacts the bleaching characteristics. We will discuss how each of these parameters impacts the laser performance.« less

Efficacy of detergent and water versus bleach for disinfection of direct contact ophthalmic lenses.

PubMed

Abbey, Ashkan M; Gregori, Ninel Z; Surapaneni, Krishna; Miller, Darlene

2014-06-01

Although manufacturers recommend cleaning ophthalmic lenses with detergent and water and then with a specific disinfectant, disinfectants are rarely used in ophthalmic practices. The aim of this pilot study was to evaluate the efficacy of detergent and water versus that of bleach, a recommended disinfectant, to eliminate common ocular bacteria and viruses from ophthalmic lenses. Three bacterial strains (Staphylococcus epidermidis, Corynebacterium straitum, and methicillin-resistant Staphylococcus aureus and 2 viral strains (adenovirus and herpes simplex virus [HSV] type-1) were individually inoculated onto 20 gonioscopy and laser lenses. The lenses were washed with detergent and water and then disinfected with 10% bleach. All the lenses were cultured after inoculation, after washing with detergent and water, and after disinfecting with the bleach. Bacterial cultures in thioglycollate broth were observed for 3 weeks, and viral cultures were observed for 2 weeks. The presence of viruses was also detected by multiplex polymerase chain reaction (PCR). All 20 lenses inoculated with S. epidermidis, C. straitum, adenovirus, and HSV-1 showed growth after inoculation but no growth after washing with detergent/water and after disinfecting with the bleach. All lenses showed positive HSV and adenovirus PCR results after inoculation and negative PCR results after washing with detergent/water and after disinfecting with bleach. All methicillin-resistant S. aureus-contaminated lenses showed growth after inoculation and no growth after washing with detergent and water. However, 1 lens showed positive growth after disinfecting with bleach. Cleaning with detergent and water seemed to effectively eliminate bacteria and viruses from the surface of contaminated ophthalmic lenses. Further studies are warranted to design practical disinfection protocols that minimize lens damage.

Short communication: The influence of solids concentration and bleaching agent on bleaching efficacy and flavor of sweet whey powder.

PubMed

Jervis, M G; Smith, T J; Drake, M A

2015-04-01

Recent studies have demonstrated the effect of bleaching conditions and bleaching agent on flavor and functional properties of whey protein ingredients. Solids concentration at bleaching significantly affected bleaching efficacy and flavor effects of different bleaching agents. It is not known if these parameters influence quality of sweet whey powder (SWP). The purpose of this study was to determine the effects of solids concentration and bleaching agent on the flavor and bleaching efficacy of SWP. Colored cheddar whey was manufactured, fat separated, and pasteurized. Subsequently, the whey (6.7% solids) was bleached, concentrated using reverse osmosis (RO) to 14% solids, and then spray dried, or whey was concentrated before bleaching and then spray dried. Bleaching treatments included a control (no bleaching, 50 °C, 60 min), hydrogen peroxide (HP; 250 mg/kg, 50 °C, 60 min), benzoyl peroxide (50 mg/kg, 50 °C, 60 min), lactoperoxidase (20 mg/kg of HP, 50 °C, 30 min), and external peroxidase (MaxiBright, DSM Food Specialties, Delft, the Netherlands; 2 dairy bleaching units/mL, 50 °C, 30 min). The experiment was repeated in triplicate. Sensory properties and volatile compounds of SWP were evaluated by a trained panel and gas chromatography-mass spectrometry, respectively. Bleaching efficacy (norbixin destruction) and benzoic acid were measured by HPLC. Differences in bleaching efficacy, sensory and volatile compound profiles, and benzoic acid were observed with different bleaching agents, consistent with previous studies. Solids concentration affected bleaching efficacy of HP, but not other bleaching agents. The SWP from whey bleached with HP or lactoperoxidase following RO had increased cardboard and fatty flavors and higher concentrations of lipid oxidation compounds compared with SWP from whey bleached before RO. The SWP bleached with benzoyl peroxide after RO contained less benzoic acid than SWP from whey bleached before RO. These results indicate that solids concentration at bleaching and bleaching agent affect quality of SWP. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Comparison of laser and power bleaching techniques in tooth color change.

PubMed

Fekrazad, Reza; Alimazandarani, Shervin; Kalhori, Katayoun Am; Assadian, Hadi; Mirmohammadi, Seyed-Mahdi

2017-04-01

Laser-assisted bleaching uses laser beam to accelerate release of free radicals within the bleaching gel to decrease time of whitening procedure. The aim of this study was to compare the efficacy of power bleaching using Opalescence Xtra Boost® and laser bleaching technique using LaserSmile gel and diode laser as an activator in their tooth whitening capacity. Student t test showed that the laser bleaching group significantly outperformed the power bleaching group in changing ∆E ( p =0.977). Similarly, while comparing the groups in changing ∆L, the laser bleaching group indicated significantly superior results ( p =0.953). Statistical data from student t test while comparing the groups in changing the parameter of yellowness indicated that samples in laser bleaching group underwent a more significant reduction than power-bleached samples ( p =0.85). Correspondingly, changes in whiteness were statistically tested through student t test, showing that laser bleaching technique increased whiteness of the samples significantly more than those treated by power bleaching ( p =0.965). The digital color evaluation data was in accordance with spectrophotometry and showed that laser bleaching outperformed power bleaching technique. Both techniques were able to increase whiteness and decrease yellowness ratio of the samples. ΔE decrease for laser bleaching and power bleaching groups were 3.05 and 1.67, respectively. Tooth color change in laser bleaching group was 1.88 times more than that of power bleaching group ( p <0.001). It could be concluded that under the conditions of this study, both laser-assisted and power bleaching techniques were capable of altering tooth color change, but laser bleaching was deemed a more efficient technique in this regard. Key words: Laser, power bleaching, tooth color introduction.

Mixed Oxidant Process for Control of Biological Growth in Cooling Towers

DTIC Science & Technology

2010-02-01

Concentration is < 1% (vs. 12.5% for bulk bleach ) • Will not form chlorine gas • No transport or storage of hazardous chemicals • Uses only salt as...Eliminates purchase, transport, and storage of hazardous biocide compounds such as hypochlorite or chlorine gas • Provides a constant dosage level of...patented MIOX equipment design • Chemical and biocidal properties are more effective than conventional chlorine Bulk Bleach On-Site Hypo Mixed Oxidants E

Efficacy of cold light bleaching using different bleaching times and their effects on human enamel.

PubMed

Wang, Wei; Zhu, Yuhe; Li, Jiajia; Liao, Susan; Ai, Hongjun

2013-01-01

This study investigated the efficacy of cold light bleaching using different bleaching times and the effects thereof on tooth enamel. Before and after bleaching, stained tooth specimens were subjected to visual and instrumental colorimetric assessments using Vita Shade Guide and spectrophotometric shade matching. Enamel surface alterations were examined using scanning electron microscopy (SEM) to analyze surface morphology, surface microhardness (SMH) measurement to determine changes in mechanical properties, and X-ray diffraction (XRD) to characterize post-bleaching enamel composition. Cold light bleaching successfully improved tooth color, with optimal efficacy when bleaching time was beyond 10 min. Significant differences in surface morphology were observed among the different bleaching times, but no significant differences were observed for enamel composition and surface microhardness among the different bleaching times. Results of this study revealed an association between the bleaching time of cold light bleaching and its whitening efficacy. Together with the results on enamel surface changes, this study provided positive evidence to support cold light bleaching as an in-office bleaching treatment.

Patterns of coral bleaching: Modeling the adaptive bleaching hypothesis

USGS Publications Warehouse

Ware, J.R.; Fautin, D.G.; Buddemeier, R.W.

1996-01-01

Bleaching - the loss of symbiotic dinoflagellates (zooxanthellae) from animals normally possessing them - can be induced by a variety of stresses, of which temperature has received the most attention. Bleaching is generally considered detrimental, but Buddemeier and Fautin have proposed that bleaching is also adaptive, providing an opportunity for recombining hosts with alternative algal types to form symbioses that might be better adapted to altered circumstances. Our mathematical model of this "adaptive bleaching hypothesis" provides insight into how animal-algae symbioses might react under various circumstances. It emulates many aspects of the coral bleaching phenomenon including: corals bleaching in response to a temperature only slightly greater than their average local maximum temperature; background bleaching; bleaching events being followed by bleaching of lesser magnitude in the subsequent one to several years; higher thermal tolerance of corals subject to environmental variability compared with those living under more constant conditions; patchiness in bleaching; and bleaching at temperatures that had not previously resulted in bleaching. ?? 1996 Elsevier Science B.V. All rights reserved.

Enhanced the enzymatic hydrolysis efficiency of wheat straw after combined steam explosion and laccase pretreatment.

PubMed

Qiu, Weihua; Chen, Hongzhang

2012-08-01

Laccase, capable of selectively degrading lignin while keeping cellulose intact, has been widely applied for the modification and bio-bleaching of pulp. In this study Sclerotium sp. laccase (MSLac) was employed in combination with steam explosion to evaluate the effect of this treatment on cellulose hydrolysis. Combined steam explosion with laccase pretreatment enhanced the cellulose conversion rate of wheat straw no matter in the case of successive (MSLac-Cel) and simultaneous (MSLac+Cel) MSLac and cellulase hydrolysis. The highest cellulose conversion rate of 84.23% was obtained when steam-exploded wheat straw (SEWS) (1.3 MPa, 5 min) was treated by MSLac+Cel at a laccase loading of 0.55 U g(-1) substrate. FT-IR and SEM analyses indicated that MSLac oxidized the phenol and changed electron configuration of the ring, which contributed to loosening the compact wrap of lignin-carbohydrate complex and consequently enhancing the enzymatic hydrolysis efficiency of cellulose. This article provided a promising method for lignocellulose bio-pretreatment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Plasmonic bio-sensing for the Fenna-Matthews-Olson complex

NASA Astrophysics Data System (ADS)

Chen, Guang-Yin; Lambert, Neill; Shih, Yen-An; Liu, Meng-Han; Chen, Yueh-Nan; Nori, Franco

2017-01-01

We study theoretically the bio-sensing capabilities of metal nanowire surface plasmons. As a specific example, we couple the nanowire to specific sites (bacteriochlorophyll) of the Fenna-Matthews-Olson (FMO) photosynthetic pigment protein complex. In this hybrid system, we find that when certain sites of the FMO complex are subject to either the suppression of inter-site transitions or are entirely disconnected from the complex, the resulting variations in the excitation transfer rates through the complex can be monitored through the corresponding changes in the scattering spectra of the incident nanowire surface plasmons. We also find that these changes can be further enhanced by changing the ratio of plasmon-site couplings. The change of the Fano lineshape in the scattering spectra further reveals that “site 5” in the FMO complex plays a distinct role from other sites. Our results provide a feasible way, using single photons, to detect mutation-induced, or bleaching-induced, local defects or modifications of the FMO complex, and allows access to both the local and global properties of the excitation transfer in such systems.

Cold enzymatic bleaching of fluid whey.

PubMed

Campbell, R E; Drake, M A

2013-01-01

Chemical bleaching of fluid whey and retentate with hydrogen peroxide (HP) alone requires high concentrations (100-500 mg of HP/kg) and recent studies have demonstrated that off-flavors are generated during chemical bleaching that carry through to spray-dried whey proteins. Bleaching of fluid whey and retentate with enzymes such as naturally present lactoperoxidase or an exogenous commercial peroxidase (EP) at cold temperatures (4°C) may be a viable alternative to traditional chemical bleaching of whey. The objective of this study was to determine the optimum level of HP for enzymatic bleaching (both lactoperoxidase and EP) at 4°C and to compare bleaching efficacy and sensory characteristics to HP chemical bleaching at 4°C. Selected treatments were subsequently applied for whey protein concentrate with 80% protein (WPC80) manufacture. Fluid Cheddar whey and retentate (80% protein) were manufactured in triplicate from pasteurized whole milk. The optimum concentration of HP (0 to 250 mg/kg) to activate enzymatic bleaching at 4°C was determined by quantifying the loss of norbixin. In subsequent experiments, bleaching efficacy, descriptive sensory analysis, and volatile compounds were monitored at selected time points. A control with no bleaching was also evaluated. Enzymatic bleaching of fluid whey and retentate at 4°C resulted in faster bleaching and higher bleaching efficacy (color loss) than bleaching with HP alone at 250 mg/kg. Due to concentrated levels of naturally present lactoperoxidase, retentate bleached to completion (>80% norbixin destruction in 30 min) faster than fluid whey at 4°C (>80% norbixin destruction in 12h). In fluid whey, the addition of EP decreased bleaching time. Spray-dried WPC80 from bleached wheys, regardless of bleaching treatment, were characterized by a lack of sweet aromatic and buttery flavors, and the presence of cardboard flavor concurrent with higher relative abundance of 1-octen-3-ol and 1-octen-3-one. Among enzymatically bleached WPC80, lactoperoxidase-bleached WPC80 contained higher relative abundance of 2,3-octadienone, 2-pentyl furan, and hexanal than those bleached with added EP. Bleach times, bleaching efficacy, and flavor results suggest that enzymatic bleaching may be a viable and desirable alternative to HP bleaching of fluid whey or retentate. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Efficacy and persistence of tooth bleaching using a diode laser with three different treatment regimens.

PubMed

Al Quran, Firas A M; Mansour, Yasar; Al-Hyari, Sabaa; Al Wahadni, Ahed; Mair, Lawrence

2011-01-01

Studies have measured the effectiveness of tooth bleaching, however there are very few studies that have measured the persistence in color change after a 6-month follow-up. This study assessed the efficacy of the laser bleaching process using different regimens, and the persistence of color change over a 6-month period. Sixty patients divided into three equal groups were subjected to bleaching using a diode laser with 34% hydrogen peroxide. Group 1: patients subjected to one session of laser bleaching. Group 2: patients subjected to two sessions of laser bleaching with a 1-week interval. Group 3: the same as Group 2 but followed by home bleaching once a month for 3 months. The color was assessed four times: before bleaching, directly after bleaching, 3 months after bleaching, and 6 months after bleaching. All teeth had a significant color change at 6 months, but all teeth had regressed from the maximum value. There was significantly less regression in color for Group 3, followed by Groups 2 and 1, respectively. The combined technique of in-office laser bleaching for two sessions with a 1-week interval, followed by home bleaching once a month for 3 months gave more persistence in color change. In-office power bleaching using a laser assisted hydrogen peroxide system repeated after a week, combined with home bleaching once a month for 3 months, is an effective bleaching regimen with less color regression after 6 months compared to a regimen of in-office bleaching alone.

Refining of crude rubber seed oil as a feedstock for biofuel production.

PubMed

Gurdeep Singh, Haswin Kaur; Yusup, Suzana; Abdullah, Bawadi; Cheah, Kin Wai; Azmee, Fathin Nabilah; Lam, Hon Loong

2017-12-01

Crude rubber seed oil is a potential source for biofuel production. However it contains undesirable impurities such as peroxides and high oxidative components that not only affect the oil stability, colour and shelf-life but promote insoluble gums formation with time that could cause deposition in the combustion engines. Therefore to overcome these problems the crude rubber seed oil is refined by undergoing degumming and bleaching process. The effect of bleaching earth dosage (15-40 wt %), phosphoric acid dosage (0.5-1.0 wt %) and reaction time (20-40 min) were studied over the reduction of the peroxide value in a refined crude rubber seed oil. The analysis of variance shows that bleaching earth dosage was the most influencing factor followed by reaction time and phosphoric acid dosage. A minimum peroxide value of 0.1 milliequivalents/gram was achieved under optimized conditions of 40 wt % of bleaching earth dosage, 1.0 wt % of phosphoric acid dosage and 20 min of reaction time using Response Surface Methodology design. Copyright © 2017 Elsevier Ltd. All rights reserved.

Engineering and Applications of fungal laccases for organic synthesis

PubMed Central

Kunamneni, Adinarayana; Camarero, Susana; García-Burgos, Carlos; Plou, Francisco J; Ballesteros, Antonio; Alcalde, Miguel

2008-01-01

Laccases are multi-copper containing oxidases (EC 1.10.3.2), widely distributed in fungi, higher plants and bacteria. Laccase catalyses the oxidation of phenols, polyphenols and anilines by one-electron abstraction, with the concomitant reduction of oxygen to water in a four-electron transfer process. In the presence of small redox mediators, laccase offers a broader repertory of oxidations including non-phenolic substrates. Hence, fungal laccases are considered as ideal green catalysts of great biotechnological impact due to their few requirements (they only require air, and they produce water as the only by-product) and their broad substrate specificity, including direct bioelectrocatalysis. Thus, laccases and/or laccase-mediator systems find potential applications in bioremediation, paper pulp bleaching, finishing of textiles, bio-fuel cells and more. Significantly, laccases can be used in organic synthesis, as they can perform exquisite transformations ranging from the oxidation of functional groups to the heteromolecular coupling for production of new antibiotics derivatives, or the catalysis of key steps in the synthesis of complex natural products. In this review, the application of fungal laccases and their engineering by rational design and directed evolution for organic synthesis purposes are discussed. PMID:19019256

Production of a cellulase-free alkaline xylanase from Bacillus pumilus MTCC 5015 by submerged fermentation and its application in biobleaching.

PubMed

Thomas, Leya; Sindhu, Raveendran; Binod, Parameswaran; Pandey, Ashok

2015-06-01

Here, we described the production of a cellulase-free alkaline xylanase from Bacillus pumilus MTCC 5015 by submerged fermentation and its application in biobleaching. Various process parameters affecting xylanase production by B. pumilus were optimized by adopting a Plackett-Burman design (PBD) as well as Response surface methodology (RSM). These statistical methods aid in improving the enzyme yield by analysing the individual crucial components of the medium. Maximum production was obtained with 4% yeast extract, 0.08% magnesium sulphate, 30 h of inoculum age, incubation temperature of 33.5 degrees C and pH 9.0. Under optimized conditions, the xylanase activity was 372 IU/ml. Media engineering improved a 5-fold increase in the enzyme production. Scanning electron microscopy (SEM) showed significant changes on the surface of xylanase treated pulps as a result of xylan hydrolysis. Increased roughness of paper carton fibres was apparent in scanning electron micrograph due to opening of the micro fibrils present on the surface by xylanase action. The untreated pulp did not show any such change. These results demonstrated that the B. pumilus MTCC 5015 xylanase was effective in bio-bleaching of paper carton.

A dynamic bioenergetic model for coral-Symbiodinium symbioses and coral bleaching as an alternate stable state.

PubMed

Cunning, Ross; Muller, Erik B; Gates, Ruth D; Nisbet, Roger M

2017-10-27

Coral reef ecosystems owe their ecological success - and vulnerability to climate change - to the symbiotic metabolism of corals and Symbiodinium spp. The urgency to understand and predict the stability and breakdown of these symbioses (i.e., coral 'bleaching') demands the development and application of theoretical tools. Here, we develop a dynamic bioenergetic model of coral-Symbiodinium symbioses that demonstrates realistic steady-state patterns in coral growth and symbiont abundance across gradients of light, nutrients, and feeding. Furthermore, by including a mechanistic treatment of photo-oxidative stress, the model displays dynamics of bleaching and recovery that can be explained as transitions between alternate stable states. These dynamics reveal that "healthy" and "bleached" states correspond broadly to nitrogen- and carbon-limitation in the system, with transitions between them occurring as integrated responses to multiple environmental factors. Indeed, a suite of complex emergent behaviors reproduced by the model (e.g., bleaching is exacerbated by nutrients and attenuated by feeding) suggests it captures many important attributes of the system; meanwhile, its modular framework and open source R code are designed to facilitate further problem-specific development. We see significant potential for this modeling framework to generate testable hypotheses and predict integrated, mechanistic responses of corals to environmental change, with important implications for understanding the performance and maintenance of symbiotic systems. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

Biobleaching of wheat straw-rich soda pulp with alkalophilic laccase from gamma-proteobacterium JB: optimization of process parameters using response surface methodology.

PubMed

Singh, Gursharan; Ahuja, Naveen; Batish, Mona; Capalash, Neena; Sharma, Prince

2008-11-01

An alkalophilic laccase from gamma-proteobacterium JB was applied to wheat straw-rich soda pulp to check its bleaching potential by using response surface methodology based on central composite design. The design was employed by selecting laccase units, ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) concentration and pH as model factors. The results of second order factorial design experiments showed that all three independent variables had significant effect on brightness and kappa number of laccase-treated pulp. Optimum conditions for biobleaching of pulp with laccase preparation (specific activity, 65 nkat mg(-1) protein) were 20 nkat g(-1) of pulp, 2mM ABTS and pH 8.0 which enhanced brightness by 5.89% and reduced kappa number by 21.1% within 4h of incubation at 55 degrees C, without further alkaline extraction of pulp. Tear index (8%) and burst index (18%) also improved for laccase-treated pulp as compared to control raw pulp. Treatment of chemically (CEH1H2) bleached pulp with laccase showed significant effect on release of chromophores, hydrophobic and reducing compounds. Laccase-prebleaching of raw pulp reduced the use of hypochlorite by 10% to achieve brightness of resultant hand sheets similar to the fully chemically bleached pulp.

Effect of the Purple Corn Beverage "Chicha Morada" in Composite Resin during Dental Bleaching.

PubMed

Acuña, Eric Dario; Delgado-Cotrina, Leyla; Rumiche, Francisco Aurelio; Tay, Lidia Yileng

2016-01-01

During dental bleaching the staining potential of the surface would increase. This study aims to evaluate the staining susceptibility of one bleached composite resin after the exposure to three different beverages: Peruvian purple corn based beverage (chicha morada), green tea, and distilled water. Thirty disk-shaped specimens of one nanofill composite resin were prepared. The specimens were then divided into six groups (n = 5): purple corn (P), purple corn + bleaching (PB), green tea (T), green tea + bleaching (TB), distilled water (W), and distilled water + bleaching (WB). In groups that received bleaching, two sessions of bleaching with 35% hydrogen peroxide were done. Following bleaching, specimens were exposed to each liquid thirty minutes daily. Color was measured with a digital spectrophotometer. For statistical analysis, color measurement differences between the obtained results were used: during bleaching, after bleaching, and during + after bleaching. Two-way ANOVA was used to compare the color changes in the resins of all groups (p < 0.05). We conclude that all the evaluated beverages produced changes of color in the composite resin regardless of the bleaching procedure. However, purple corn was the only beverage that caused a perceptible color change (ΔE > 3.3).

Effect of the Purple Corn Beverage “Chicha Morada” in Composite Resin during Dental Bleaching

PubMed Central

Acuña, Eric Dario; Delgado-Cotrina, Leyla; Rumiche, Francisco Aurelio

2016-01-01

During dental bleaching the staining potential of the surface would increase. This study aims to evaluate the staining susceptibility of one bleached composite resin after the exposure to three different beverages: Peruvian purple corn based beverage (chicha morada), green tea, and distilled water. Thirty disk-shaped specimens of one nanofill composite resin were prepared. The specimens were then divided into six groups (n = 5): purple corn (P), purple corn + bleaching (PB), green tea (T), green tea + bleaching (TB), distilled water (W), and distilled water + bleaching (WB). In groups that received bleaching, two sessions of bleaching with 35% hydrogen peroxide were done. Following bleaching, specimens were exposed to each liquid thirty minutes daily. Color was measured with a digital spectrophotometer. For statistical analysis, color measurement differences between the obtained results were used: during bleaching, after bleaching, and during + after bleaching. Two-way ANOVA was used to compare the color changes in the resins of all groups (p < 0.05). We conclude that all the evaluated beverages produced changes of color in the composite resin regardless of the bleaching procedure. However, purple corn was the only beverage that caused a perceptible color change (ΔE > 3.3). PMID:27034897

Microhardness of demineralized enamel following home bleaching and laser-assisted in office bleaching

PubMed Central

Ghanbarzadeh, Majid; Akbari, Majid; Hamzei, Haniye

2015-01-01

Background There is little data regarding the effect of tooth whitening on microhardness of white spot lesions. This study was conducted to investigate the effect of home-bleaching and laser-assisted in-office bleaching on microhardness of demineralized enamel. Material and Methods Forty bovine incisors were selected and immersed in a demineralizing solution for 12 weeks to induce white spot lesions. Enamel blocks were prepared and randomly assigned to two groups of 20 each. The first group underwent home bleaching with 15% carbamide peroxide which was applied for 8 hours a day over a period of 15 days. In the second group, in-office bleaching was performed by 40% hydrogen peroxide and powered by irradiation from an 810 nm gallium-aluminum-arsenide (GaAlAs) diode laser (CW, 2W). This process was performed for 3 sessions every seven days, in 15 days. The specimens were stored in Fusayama Meyer artificial saliva during the experiment. Surface microhardness was assessed before and after the bleaching therapies in both groups. Results Microhardness decreased significantly following both home bleaching and laser-assisted in-office bleaching (p<0.05). There were no significant differences in hardness values among the two groups either before (p=0.131) or after (p=0.182) the bleaching procedures. Conclusions Tooth whitening through home bleaching or laser-assisted in-office bleaching can result in a significant reduction in microhardness of white spot lesions. Therefore, it is suggested to take protective measures on bleached demineralized enamel. Key words:White spot lesion, bleaching, laser, microhardness, demineralized enamel, home bleaching, in-office bleaching. PMID:26330939

Large-scale bleaching of corals on the Great Barrier Reef.

PubMed

Hughes, T P; Kerry, J T; Simpson, T

2018-02-01

In 2015-2016, record temperatures triggered a pan-tropical episode of coral bleaching. In the southern hemisphere summer of March-April 2016, we used aerial surveys to measure the level of bleaching on 1,156 individual reefs throughout the 2,300 km length of the Great Barrier Reef, the world's largest coral reef system. The accuracy of the aerial scores was ground-truthed with detailed underwater surveys of bleaching at 260 sites (104 reefs), allowing us to compare aerial and underwater bleaching data with satellite-derived temperatures and with associated model predictions of bleaching. The severity of bleaching on individual reefs in 2016 was tightly correlated with the level of local heat exposure: the southernmost region of the Great Barrier Reef escaped with only minor bleaching because summer temperatures there were close to average. Gradients in nutrients and turbidity from inshore to offshore across the Great Barrier Reef had minimal effect on the severity of bleaching. Similarly, bleaching was equally severe on reefs that are open or closed to fishing, once the level of satellite-derived heat exposure was accounted for. The level of post-bleaching mortality, measured underwater after 7-8 months, was tightly correlated with the aerial scores measured at the peak of bleaching. Similarly, reefs with a high aerial bleaching score also experienced major shifts in species composition due to extensive mortality of heat-sensitive species. Reefs with low bleaching scores did not change in composition, and some showed minor increases in coral cover. Two earlier mass bleaching events occurred on the Great Barrier Reef in 1998 and 2002, that were less severe than 2016. In 2016, <9% of scored reefs had no bleaching, compared to 42% in 2002 and 44% in 1998. Conversely, the proportion of reefs that were severely bleached (>60% of corals affected) was four times higher in 2016. The geographic footprint of each of the three events is distinctive, and matches satellite-derived sea surface temperature patterns. Our aerial surveys indicate that past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016. This data set of aerial bleaching scores provides a historical baseline for comparison with future bleaching events. No copyright restrictions apply to the use of this data set other than citing this publication. © 2017 by the Ecological Society of America.

Influence of remineralizing gels on bleached enamel microhardness in different time intervals.

PubMed

Borges, Alessandra Bühler; Yui, Karen Cristina Kazue; D'Avila, Thaís Corrêa; Takahashi, Camila Lurie; Torres, Carlos Rocha Gomes; Borges, Alexandre Luis Souto

2010-01-01

This study evaluated the influence of bleaching gel pH, the effect of applying remineralizing gels after bleaching and the effect of artificial saliva on enamel microhardness. Seventy bovine incisors were divided into three groups: Group 1 (n=10) received no bleaching procedure (control); Group 2 was bleached with a 35% hydrogen peroxide neutral gel (n=30) and Group 3 was bleached with a 35% hydrogen peroxide acid gel (n=30). Each experimental group was subdivided into three groups (n=10) according to the post-bleaching treatment: storage in artificial saliva, application of a fluoride gel and application of a combination of calcium and fluoride gel. The specimens were stored in artificial saliva for 7, 15 and 30 days and enamel microhardness was evaluated. The Vickers microhardness data were analyzed by three-way RM ANOVA, which revealed a significant difference only for treatment factor. The Tukey's test showed that the groups bleached followed by no additional treatment exhibited microhardness means significantly lower than the bleached groups treated with remineralizing gels. The Dunnet's test showed a significant difference only for the group bleached with acid gel without remineralizing treatment compared to the control group measured immediately after bleaching. It was concluded that acid bleaching gel significantly reduced enamel microhardness and that use of remineralizing gels after bleaching can significantly enhance the microhardness of bleached enamel.

Changes in Bleaching Susceptibility among Corals Subject to Ocean Warming and Recurrent Bleaching in Moorea, French Polynesia

PubMed Central

Pratchett, Morgan S.; McCowan, Dominique; Maynard, Jeffrey A.; Heron, Scott F.

2013-01-01

Background Climate-induced coral bleaching poses a major threat to coral reef ecosystems, mostly because of the sensitivities of key habitat-forming corals to increasing temperature. However, susceptibility to bleaching varies greatly among coral genera and there are likely to be major changes in the relative abundance of different corals, even if the wholesale loss of corals does not occur for several decades. Here we document variation in bleaching susceptibility among key genera of reef-building corals in Moorea, French Polynesia, and compare bleaching incidence during mass-bleaching events documented in 1991, 1994, 2002 and 2007. Methodology/Principal Findings This study compared the proportion of colonies that bleached for four major genera of reef-building corals (Acropora, Montipora, Pocillopora and Porites), during each of four well-documented bleaching events from 1991 to 2007. Acropora and Montipora consistently bleached in far greater proportions (up to 98%) than Pocillopora and Porites. However, there was an apparent and sustained decline in the proportion of colonies that bleached during successive bleaching events, especially for Acropora and Montipora. In 2007, only 77% of Acropora colonies bleached compared with 98% in 1991. Temporal variation in the proportion of coral colonies bleached may be attributable to differences in environmental conditions among years. Alternately, the sustained declines in bleaching incidence among highly susceptible corals may be indicative of acclimation or adaptation. Conclusions/Significance Coral genera that are highly susceptible to coral bleaching, and especially Acropora and Montipora, exhibit temporal declines in their susceptibility to thermal anomalies at Moorea, French Polynesia. One possible explanation for these findings is that gradual removal of highly susceptible genotypes (through selective mortality of individuals, populations, and/or species) is producing a coral assemblage that is more resistant to sustained and ongoing ocean warming. PMID:23922992

Changes in bleaching susceptibility among corals subject to ocean warming and recurrent bleaching in Moorea, French Polynesia.

PubMed

Pratchett, Morgan S; McCowan, Dominique; Maynard, Jeffrey A; Heron, Scott F

2013-01-01

Climate-induced coral bleaching poses a major threat to coral reef ecosystems, mostly because of the sensitivities of key habitat-forming corals to increasing temperature. However, susceptibility to bleaching varies greatly among coral genera and there are likely to be major changes in the relative abundance of different corals, even if the wholesale loss of corals does not occur for several decades. Here we document variation in bleaching susceptibility among key genera of reef-building corals in Moorea, French Polynesia, and compare bleaching incidence during mass-bleaching events documented in 1991, 1994, 2002 and 2007. This study compared the proportion of colonies that bleached for four major genera of reef-building corals (Acropora, Montipora, Pocillopora and Porites), during each of four well-documented bleaching events from 1991 to 2007. Acropora and Montipora consistently bleached in far greater proportions (up to 98%) than Pocillopora and Porites. However, there was an apparent and sustained decline in the proportion of colonies that bleached during successive bleaching events, especially for Acropora and Montipora. In 2007, only 77% of Acropora colonies bleached compared with 98% in 1991. Temporal variation in the proportion of coral colonies bleached may be attributable to differences in environmental conditions among years. Alternately, the sustained declines in bleaching incidence among highly susceptible corals may be indicative of acclimation or adaptation. Coral genera that are highly susceptible to coral bleaching, and especially Acropora and Montipora, exhibit temporal declines in their susceptibility to thermal anomalies at Moorea, French Polynesia. One possible explanation for these findings is that gradual removal of highly susceptible genotypes (through selective mortality of individuals, populations, and/or species) is producing a coral assemblage that is more resistant to sustained and ongoing ocean warming.

Taxonomic, spatial and temporal patterns of bleaching in anemones inhabited by anemonefishes.

PubMed

Hobbs, Jean-Paul A; Frisch, Ashley J; Ford, Benjamin M; Thums, Michele; Saenz-Agudelo, Pablo; Furby, Kathryn A; Berumen, Michael L

2013-01-01

Rising sea temperatures are causing significant destruction to coral reef ecosystems due to coral mortality from thermally-induced bleaching (loss of symbiotic algae and/or their photosynthetic pigments). Although bleaching has been intensively studied in corals, little is known about the causes and consequences of bleaching in other tropical symbiotic organisms. This study used underwater visual surveys to investigate bleaching in the 10 species of anemones that host anemonefishes. Bleaching was confirmed in seven anemone species (with anecdotal reports of bleaching in the other three species) at 10 of 19 survey locations spanning the Indo-Pacific and Red Sea, indicating that anemone bleaching is taxonomically and geographically widespread. In total, bleaching was observed in 490 of the 13,896 surveyed anemones (3.5%); however, this percentage was much higher (19-100%) during five major bleaching events that were associated with periods of elevated water temperatures and coral bleaching. There was considerable spatial variation in anemone bleaching during most of these events, suggesting that certain sites and deeper waters might act as refuges. Susceptibility to bleaching varied between species, and in some species, bleaching caused reductions in size and abundance. Anemones are long-lived with low natural mortality, which makes them particularly vulnerable to predicted increases in severity and frequency of bleaching events. Population viability will be severely compromised if anemones and their symbionts cannot acclimate or adapt to rising sea temperatures. Anemone bleaching also has negative effects to other species, particularly those that have an obligate relationship with anemones. These effects include reductions in abundance and reproductive output of anemonefishes. Therefore, the future of these iconic and commercially valuable coral reef fishes is inextricably linked to the ability of host anemones to cope with rising sea temperatures associated with climate change.

Validation of degree heating weeks as a coral bleaching index in the northwestern Pacific

NASA Astrophysics Data System (ADS)

Kayanne, Hajime

2017-03-01

Mass bleaching is the most significant threat to coral reefs. The United States National Oceanic and Atmospheric Administration monitors world sea surface temperature (SST) and releases warnings for bleaching based on degree heating weeks (DHW), which is the accumulation of temperature anomalies exceeding the monthly maximum mean SST for a given region. DHW values >4.0 °C-weeks are thought to induce bleaching, and those >8.0 °C-weeks are thought to result in widespread bleaching and some mortality. This study validates the effectiveness of DHW as a mass bleaching index by on-site historical observation at eight sites in the northwestern Pacific Ocean. The mass bleaching events occurred during different years at different sites. The recorded years of the bleaching events matched well with DHW values >8 °C-weeks, and the logistically projected probability of bleaching against DHW showed a positive relationship. DHW provides a reasonable threshold for bleaching.

Dental bleaching on teeth submitted to enamel microabrasion 30 years ago-a case report of patients' compliance during bleaching treatment.

PubMed

Sundfeld, Daniel; Pavani, Caio Cesar; Schott, Timm Cornelius; Machado, Lucas Silveira; Pini, Núbia Inocêncya Pavesi; Bertoz, André Pinheiro de Magalhães; Sundfeld, Renato Herman

2018-04-20

The present dental bleaching case report describes a new method that precisely quantifies the daily wearing-times of the bleaching product by inserting a microsensor in the acetate custom tray. The bleaching efficacy was also discussed since the patient was previously submitted to enamel microabrasion. The patient was submitted to enamel microabrasion in 1987, and bleaching treatment was performed in 2005. In 2017, re-bleaching was executed using 10% peroxide carbamide. The electronic microsensor, TheraMon (TheraMon® microelectronic system; Sales Agency Gschladt, Hargelsberg, Austria), was embedded in the labial region of the upper and lower acetate trays to evaluate the wearing-times of the acetate trays/bleaching product. The patient was instructed to wear the tray for 6 to 8 h/day while sleeping. After 24 days of bleaching treatment, the data obtained from the TheraMon electronic devices was collected and interpreted. The patient did not entirely follow the bleaching treatment as recommended, as there was no evidence of use of the upper and lower trays for some days; additionally, the bleaching product was used for shorter and longer periods than was instructed. The TheraMon microeletronic device precisely measured the wearing-times of the acetate tray/bleaching product during the bleaching treatment. Teeth submitted to enamel microabrasion presented with a healthy clinical appearance after 30 years. Measuring the length and frequency of use of an acetate tray/bleaching product can be important to clinicians and patients for obtaining a controlled and adequate bleaching treatment.

The differential effects of increasing frequency and magnitude of extreme events on coral populations.

PubMed

Fabina, Nicholas S; Baskett, Marissa L; Gross, Kevin

2015-09-01

Extreme events, which have profound ecological consequences, are changing in both frequency and magnitude with climate change. Because extreme temperatures induce coral bleaching, we can explore the relative impacts of changes in frequency and magnitude of high temperature events on coral reefs. Here, we combined climate projections and a dynamic population model to determine how changing bleaching regimes influence coral persistence. We additionally explored how coral traits and competition with macroalgae mediate changes in bleaching regimes. Our results predict that severe bleaching events reduce coral persistence more than frequent bleaching. Corals with low adult mortality and high growth rates are successful when bleaching is mild, but bleaching resistance is necessary to persist when bleaching is severe, regardless of frequency. The existence of macroalgae-dominated stable states reduces coral persistence and changes the relative importance of coral traits. Building on previous studies, our results predict that management efforts may need to prioritize protection of "weaker" corals with high adult mortality when bleaching is mild, and protection of "stronger" corals with high bleaching resistance when bleaching is severe. In summary, future reef projections and conservation targets depend on both local bleaching regimes and biodiversity.

Fixation-free rehalogenating bleached reflection holograms recorded on BB-640 plates

NASA Astrophysics Data System (ADS)

Neipp, C.; Pascual, I.; Beléndez, A.

2000-08-01

Fixation-free rehalogenating bleaching is an interesting process for the production of phase reflection holograms. The shrinkage of the emulsion is reduced in comparison with other bleaching methods (reversal bleaching or rehalogenating bleaching with a fixation step), which is particularly interesting in the case of reflection holograms. In this communication, we present experimental results for fixation-free rehalogenating bleached holograms derived from the novel BB-640 emulsion, a red-sensitive ultra-fine grain emulsion from Holographic Recording Technologies using an R-10 type bleach bath. The influence of the potassium bromide concentrations in the bleach solution on the final quality of the holograms is also studied. The concentrations of the different components of the bleach solution are adjusted to obtain the highest diffraction efficiencies. A high diffraction efficiency of 72% is obtained.

Effect of temperature and bleaching agent on bleaching of liquid Cheddar whey.

PubMed

Listiyani, M A D; Campbell, R E; Miracle, R E; Barbano, D M; Gerard, P D; Drake, M A

2012-01-01

The use of whey protein as an ingredient in foods and beverages is increasing, and thus demand for colorless and mild-tasting whey protein is rising. Bleaching is commonly applied to fluid colored cheese whey to decrease color, and different temperatures and bleach concentrations are used. The objectives of this study were to compare the effects of hot and cold bleaching, the point of bleaching (before or after fat separation), and bleaching agent on bleaching efficacy and volatile components of liquid colored and uncolored Cheddar whey. First, Cheddar whey was manufactured, pasteurized, fat-separated, and subjected to one of a number of hot (68°C) or cold (4°C) bleaching applications [hydrogen peroxide (HP) 50 to 500 mg/kg; benzoyl peroxide (BP) 25 to 100 mg/kg] followed by measurement of residual norbixin and color by reflectance. Bleaching agent concentrations were then selected for the second trial. Liquid colored Cheddar whey was manufactured in triplicate and pasteurized. Part of the whey was collected (no separation, NSE) and the rest was subjected to fat separation (FSE). The NSE and FSE wheys were then subdivided and bleaching treatments (BP 50 or 100 mg/kg and HP 250 or 500 mg/kg) at 68°C for 30 min or 4°C for 16 h were applied. Control NSE and FSE with no added bleach were also subjected to each time-temperature combination. Volatile compounds from wheys were evaluated by gas chromatography-mass spectrometry, and norbixin (annatto) was extracted and quantified to compare bleaching efficacy. Proximate analysis, including total solids, protein, and fat contents, was also conducted. Liquid whey subjected to hot bleaching at both concentrations of HP or at 100mg/kg BP had greater lipid oxidation products (aldehydes) compared with unbleached wheys, 50mg/kg BP hot-bleached whey, or cold-bleached wheys. No effect was detected between NSE and FSE liquid Cheddar whey on the relative abundance of volatile lipid oxidation products. Wheys bleached with BP had lower norbixin content compared with wheys bleached with HP. Bleaching efficacy of HP was decreased at 4°C compared with 68°C, whereas that of BP was not affected by temperature. These results suggest that fat separation of liquid Cheddar whey has no effect on bleaching efficacy or lipid oxidation and that hot bleaching may result in increased lipid oxidation in fluid whey. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Predicting coral bleaching in response to environmental stressors using 8 years of global-scale data.

PubMed

Yee, Susan Harrell; Barron, Mace G

2010-02-01

Coral reefs have experienced extensive mortality over the past few decades as a result of temperature-induced mass bleaching events. There is an increasing realization that other environmental factors, including water mixing, solar radiation, water depth, and water clarity, interact with temperature to either exacerbate bleaching or protect coral from mass bleaching. The relative contribution of these factors to variability in mass bleaching at a global scale has not been quantified, but can provide insights when making large-scale predictions of mass bleaching events. Using data from 708 bleaching surveys across the globe, a framework was developed to predict the probability of moderate or severe bleaching as a function of key environmental variables derived from global-scale remote-sensing data. The ability of models to explain spatial and temporal variability in mass bleaching events was quantified. Results indicated approximately 20% improved accuracy of predictions of bleaching when solar radiation and water mixing, in addition to elevated temperature, were incorporated into models, but predictive accuracy was variable among regions. Results provide insights into the effects of environmental parameters on bleaching at a global scale.

Spatial consequences of bleaching adaptation in cat retinal ganglion cells.

PubMed Central

Bonds, A B; Enroth-Cugell, C

1981-01-01

1. Experiments were conducted to study the effects of localized bleaching on the centre responses of rod-driven cat retinal ganglion cells. 2. Stimulation as far as 2 degrees from the bleaching site yielded responses which were reduced nearly as much as those generated at the bleaching site. Bleaching in the receptive field middle reduced responsiveness at a site 1 degrees peripheral more than bleaching at that peripheral site itself. 3. The effectiveness of a bleach in reducing centre responsiveness is related to the sensitivity of the region in which the bleach is applied. 4. Response reduction after a 0.2 degree bleach followed the same temporal pattern for concentric test spots of from 0.2 to 1.8 degrees in diameter, implying a substantially uniform spread of adaptation within these bounds. 5. A linear trade-off between fraction of rhodopsin and area bleached over a range of 8:1 yields the same pattern of response reduction, implying that the non-linear nature of bleaching adaptation is a property of the adaptation pool rather than independent photoreceptors. PMID:7320894

Study of melanin bleaching after immunohistochemistry of melanin-containing tissues.

PubMed

Shen, Hongwu; Wu, Wenqiao

2015-04-01

Melanin may interfere with immunohistochemical staining. The goal of this study was to investigate the effects of trichloroisocyanuric acid (TCCA) bleaching, potassium permanganate bleaching, and potassium dichromate bleaching on melanin, tissue antigen, and 3,3'-diaminobenzidine (DAB) using melanin-containing and melanin-free tissue samples. Our results demonstrated that all 3 bleaching methods efficiently bleached melanin and partially destroyed tissue antigen. In addition, potassium permanganate bleaching and potassium dichromate bleaching clearly destroyed DAB, whereas TCCA bleaching had no significant effect on DAB. Therefore, neither potassium permanganate nor potassium dichromate is an ideal solution, whereas TCCA might be an ideal solution for melanin bleaching after the immunohistochemical staining of melanin-containing tissues. After immunostaining followed by TCCA bleaching, the melanin could be completely removed in all 120 malignant melanoma tissue sections. Compared with the control, the DAB intensity was clear, and the tissue structure and cellular nuclei were well maintained. It is worth noting that TCCA should be freshly prepared before each experiment, and used within 2 hours of its preparation. In addition, sections should not be incubated with TCCA for over 30 minutes.

The cumulative impact of annual coral bleaching can turn some coral species winners into losers.

PubMed

Grottoli, Andréa G; Warner, Mark E; Levas, Stephen J; Aschaffenburg, Matthew D; Schoepf, Verena; McGinley, Michael; Baumann, Justin; Matsui, Yohei

2014-12-01

Mass coral bleaching events caused by elevated seawater temperatures result in extensive coral loss throughout the tropics, and are projected to increase in frequency and severity. If bleaching becomes an annual event later in this century, more than 90% of coral reefs worldwide may be at risk of long-term degradation. While corals can recover from single isolated bleaching and can acclimate to recurring bleaching events that are separated by multiple years, it is currently unknown if and how they will survive and possibly acclimatize to annual coral bleaching. Here, we demonstrate for the first time that annual coral bleaching can dramatically alter thermal tolerance in Caribbean corals. We found that high coral energy reserves and changes in the dominant algal endosymbiont type (Symbiodinium spp.) facilitated rapid acclimation in Porites divaricata, whereas low energy reserves and a lack of algal phenotypic plasticity significantly increased susceptibility in Porites astreoides to bleaching the following year. Phenotypic plasticity in the dominant endosymbiont type of Orbicella faveolata did not prevent repeat bleaching, but may have facilitated rapid recovery. Thus, coral holobiont response to an isolated single bleaching event is not an accurate predictor of its response to bleaching the following year. Rather, the cumulative impact of annual coral bleaching can turn some coral species 'winners' into 'losers', and can also facilitate acclimation and turn some coral species 'losers' into 'winners'. Overall, these findings indicate that cumulative impact of annual coral bleaching could result in some species becoming increasingly susceptible to bleaching and face a long-term decline, while phenotypically plastic coral species will acclimatize and persist. Thus, annual coral bleaching and recovery could contribute to the selective loss of coral diversity as well as the overall decline of coral reefs in the Caribbean. © 2014 John Wiley & Sons Ltd.

Comparison of Tooth Color Change After Bleaching With Conventional and Different Light-Activated Methods.

PubMed

Shahabi, Sima; Assadian, Hadi; Mahmoudi Nahavandi, Alireza; Nokhbatolfoghahaei, Hanieh

2018-01-01

Introduction: The demand for esthetic dental treatments is increasing in recent years mainly due to improved oral hygiene and better maintenance of oral health and teeth in older individuals. Bleaching of discolored anterior teeth is the most popular among esthetic dental treatments. Even individuals with sound teeth and adequate esthetics seek to have whiter teeth in the anterior region. The aim of this study was to evaluate tooth color changes following conventional in-office bleaching techniques compared to light-activated methods using different light sources. Methods: Seventy sound anterior teeth (devoided of caries and/or fracture), extracted for periodontal and orthodontic reasons were selected and allocated to 7 groups: (A) control, (B) conventional bleaching (C) LED-activated bleaching, (D) KTP laser-activated bleaching, (E) diode laser-activated bleaching, (F) Nd:YAG laser-activated bleaching and (G) CO2 laser-activated bleaching. Colorimetric evaluation was carried out before and after treatment using a spectrophotoradiometer. Data were analyzed by one- and two-way analysis of variance (ANOVA) as well as multiple comparison methods. Results: The results showed that all bleaching procedures were effective in reducing the yellowness index. However, the KTP laser-activated bleaching was significantly more effective than the other techniques in 95% confidence level. It was also seen that CO2 laser activated method has outperformed groups E, F and G and the conventional bleaching without light activation was not effective at all and represented similar results with the control group. Furthermore, the groups E and G had almost the same results in decreasing the yellowness index. Conclusion: The results showed that all bleaching techniques were effective however, the KTP laser-activated bleaching was significantly more efficient, closely followed by the CO2 laser-activated bleaching technique.

Mass coral bleaching in 2010 in the southern Caribbean.

PubMed

Alemu I, Jahson Berhane; Clement, Ysharda

2014-01-01

Ocean temperatures are increasing globally and the Caribbean is no exception. An extreme ocean warming event in 2010 placed Tobago's coral reefs under severe stress resulting in widespread coral bleaching and threatening the livelihoods that rely on them. The bleaching response of four reef building taxa was monitored over a six month period across three major reefs systems in Tobago. By identifying taxa resilient to bleaching we propose to assist local coral reef managers in the decision making process to cope with mass bleaching events. The bleaching signal (length of exposure to high ocean temperatures) varied widely between the Atlantic and Caribbean reefs, but regardless of this variation most taxa bleached. Colpophyllia natans, Montastraea faveolata and Siderastrea siderea were considered the most bleaching vulnerable taxa. Interestingly, reefs with the highest coral cover showed the greatest decline reef building taxa, and conversely, reefs with the lowest coral cover showed the most bleaching but lowest change in coral cover with little algal overgrowth post-bleaching.

Mass Coral Bleaching in 2010 in the Southern Caribbean

PubMed Central

Alemu I, Jahson Berhane; Clement, Ysharda

2014-01-01

Ocean temperatures are increasing globally and the Caribbean is no exception. An extreme ocean warming event in 2010 placed Tobago's coral reefs under severe stress resulting in widespread coral bleaching and threatening the livelihoods that rely on them. The bleaching response of four reef building taxa was monitored over a six month period across three major reefs systems in Tobago. By identifying taxa resilient to bleaching we propose to assist local coral reef managers in the decision making process to cope with mass bleaching events. The bleaching signal (length of exposure to high ocean temperatures) varied widely between the Atlantic and Caribbean reefs, but regardless of this variation most taxa bleached. Colpophyllia natans, Montastraea faveolata and Siderastrea siderea were considered the most bleaching vulnerable taxa. Interestingly, reefs with the highest coral cover showed the greatest decline reef building taxa, and conversely, reefs with the lowest coral cover showed the most bleaching but lowest change in coral cover with little algal overgrowth post-bleaching. PMID:24400078

The influence of hair bleach on the ultrastructure of human hair with special reference to hair damage.

PubMed

Imai, Takehito

2011-05-01

The influence of human hair bleaching agents with different bleaching strength on the ultrastructure of human hair was studied using a transmission electron microscope (TEM) and an energy dispersive X-ray spectrometer equipped with TEM (EDS-TEM). Two kinds of bleaching agents were used: a lightener agent with a weak bleaching effect and a powder-bleach with a stronger bleaching effect. From the comparison of the bleaching properties obtained by the electronic staining of black and white hair samples, it was suggested that the permeability of hair was increased by bleaching, and there was an increase of the stainability of hair subjected to electronic staining. The bleaching action provoked the decomposition of melanin granules and the flow out of granular contents into the intermacrofibrillar matrix. Some metal elements were detected in the melanin granular matrix by EDS-TEM. As a result, the diffusion of metal elements into the intermacrofibrillar matrix promoted further damage to the hair by catalytic action with the hydrogen peroxide in the bleaching agents outside the melanin granules. Further study will lead us to the edge of the development of a new bleaching agent, which reacts only with melanin granules and causes the minimum of damage to outside the melanin granules.

Body image disturbance and skin bleaching.

PubMed

Charles, Christopher A D; McLean, Shua-Kym

2017-11-01

This study looks at body image disturbance among Jamaicans who bleach their skin. The hypothesis states that there is a positive relationship between skin bleaching and body image disturbance. The study used a convenience sample of 160 participants with a skin bleaching group (n = 80) and a non-bleaching comparison group (n = 80). The instrument included demographic questions, the body image disturbance questionnaire (BIDQ), and questions about skin bleaching. The results of a t-test revealed that the skin bleaching group (M = 1.5255, SD = 0.42169) was not significantly different from the non-bleaching group (M = 1.4938, SD = 0.74217) in terms of body image disturbance, t(158) = 0.333, p = .740. The participants who bleached did not suffer from body image disturbance. Self-reports revealed that they bleached to acquire beauty, attract a partner, elude the police, and market skin bleaching products. The practice was fashionable and popular and it made some participants feel good, while others were fans of a popular musical artiste who bleached his skin. The majority of participants bleached because of the perceived personal, social, and entrepreneurial benefits of the practice and not because they suffered emotional distress, anxiety, and functional impairment because of their skin colour. However, there was some level of BID among the minority of participants who argued that they bleached because they wanted to be pretty so they were emotionally distressed about there body image and experienced functional impairment. © 2017 The British Psychological Society.

Association Between In-Office And At-Home Tooth Bleaching: A Single Blind Randomized Clinical Trial.

PubMed

Rodrigues, João Lima; Rocha, Patrícia Souza; Pardim, Silvia Letícia de Souza; Machado, Ana Cláudia Vieira; Faria-E-Silva, André Luis; Seraidarian, Paulo Isaías

2018-01-01

This controlled randomized clinical trial evaluated the effect of associating at-home and in-office bleaching procedures on tooth sensitivity (TS) and bleaching effectiveness. Forty patients subjected to on session of in-office bleaching with 38% peroxide hydrogen. Subsequently, the patients were randomly allocated to receive a second session of in-office bleaching or to use a tray containing 10% carbamide peroxide delivered during 7 consecutive days. The worst TS score reported during or after each bleaching procedure was recorded using a verbal rating scale and TS risk (score different from 0) was calculated. Color changes were measured 7 days after each in-office session (for patients receiving in-office procedures only) or after the end of at-home bleaching (for the combined protocol), and 6 months after the last procedure for both bleaching protocols. Color was assessed by a spectrophotometer and by color match with the Vita Classical and Bleach guide scales. Statistical analyses were carried out to assess possible differences between the protocols regarding the outcomes and to analyze the effect of time of assessment on color changes. The bleaching protocol did not affect the risk for and the maximum level of TS reported, irrespective of the time of assessment. In the color evaluation, the bleaching protocol also did not affect the ultimate tooth color. In conclusion, after one in-office bleaching session, there was no difference in bleaching effectiveness and TS between performing a second in-office session and associating it with 1-week at-home bleaching.

Influence of storage, heat treatment, and solids composition on the bleaching of whey with hydrogen peroxide.

PubMed

Li, Xiaomeng E; Campbell, Rachel E; Fox, Aaron J; Gerard, Patrick D; Drake, MaryAnne

2012-07-01

The residual annatto colorant in liquid whey is bleached to provide a desired neutral color in dried whey ingredients. This study evaluated the influence of starter culture, whey solids and composition, and spray drying on bleaching efficacy. Cheddar cheese whey with annatto was manufactured with starter culture or by addition of lactic acid and rennet. Pasteurized fat-separated whey was ultrafiltered (retentate) and spray dried to 34% whey protein concentrate (WPC34). Aliquots were bleached at 60 °C for 1 h (hydrogen peroxide, 250 ppm), before pasteurization, after pasteurization, after storage at 3 °C and after freezing at -20 °C. Aliquots of retentate were bleached analogously immediately and after storage at 3 or -20 °C. Freshly spray dried WPC34 was rehydrated to 9% (w/w) solids and bleached. In a final experiment, pasteurized fat-separated whey was ultrafiltered and spray dried to WPC34 and WPC80. The WPC34 and WPC80 retentates were diluted to 7 or 9% solids (w/w) and bleached at 50 °C for 1 h. Freshly spray-dried WPC34 and WPC80 were rehydrated to 9 or 12% solids and bleached. Bleaching efficacy was measured by extraction and quantification of norbixin. Each experiment was replicated 3 times. Starter culture, fat separation, or pasteurization did not impact bleaching efficacy (P > 0.05) while cold or frozen storage decreased bleaching efficacy (P < 0.05). Bleaching efficacy of 80% (w/w) protein liquid retentate was higher than liquid whey or 34% (w/w) protein liquid retentate (P < 0.05). Processing steps, particularly holding times and solids composition, influence bleaching efficacy of whey. Optimization of whey bleaching conditions is important to reduce the negative effects of bleaching on the flavor of dried whey ingredients. This study established that liquid storage and whey composition are critical processing points that influence bleaching efficacy. © 2012 Institute of Food Technologists®

Can heterotrophic uptake of dissolved organic carbon and zooplankton mitigate carbon budget deficits in annually bleached corals?

NASA Astrophysics Data System (ADS)

Levas, Stephen; Grottoli, Andréa G.; Schoepf, Verena; Aschaffenburg, Matthew; Baumann, Justin; Bauer, James E.; Warner, Mark E.

2016-06-01

Annual coral bleaching events due to increasing sea surface temperatures are predicted to occur globally by the mid-century and as early as 2025 in the Caribbean, and severely impact coral reefs. We hypothesize that heterotrophic carbon (C) in the form of zooplankton and dissolved organic carbon (DOC) is a significant source of C to bleached corals. Thus, the ability to utilize multiple pools of fixed carbon and/or increase the amount of fixed carbon acquired from one or more pools of fixed carbon (defined here as heterotrophic plasticity) could underlie coral acclimatization and persistence under future ocean-warming scenarios. Here, three species of Caribbean coral— Porites divaricata, P. astreoides, and Orbicella faveolata—were experimentally bleached for 2.5 weeks in two successive years and allowed to recover in the field. Zooplankton feeding was assessed after single and repeat bleaching, while DOC fluxes and the contribution of DOC to the total C budget were determined after single bleaching, 11 months on the reef, and repeat bleaching. Zooplankton was a large C source for P. astreoides, but only following single bleaching. DOC was a source of C for single-bleached corals and accounted for 11-36 % of daily metabolic demand (CHARDOC), but represented a net loss of C in repeat-bleached corals. In repeat-bleached corals, DOC loss exacerbated the negative C budgets in all three species. Thus, the capacity for heterotrophic plasticity in corals is compromised under annual bleaching, and heterotrophic uptake of DOC and zooplankton does not mitigate C budget deficits in annually bleached corals. Overall, these findings suggest that some Caribbean corals may be more susceptible to repeat bleaching than to single bleaching due to a lack of heterotrophic plasticity, and coral persistence under increasing bleaching frequency may ultimately depend on other factors such as energy reserves and symbiont shuffling.

Taxonomic, Spatial and Temporal Patterns of Bleaching in Anemones Inhabited by Anemonefishes

PubMed Central

Hobbs, Jean-Paul A.; Frisch, Ashley J.; Ford, Benjamin M.; Thums, Michele; Saenz-Agudelo, Pablo; Furby, Kathryn A.; Berumen, Michael L.

2013-01-01

Background Rising sea temperatures are causing significant destruction to coral reef ecosystems due to coral mortality from thermally-induced bleaching (loss of symbiotic algae and/or their photosynthetic pigments). Although bleaching has been intensively studied in corals, little is known about the causes and consequences of bleaching in other tropical symbiotic organisms. Methodology/Principal Findings This study used underwater visual surveys to investigate bleaching in the 10 species of anemones that host anemonefishes. Bleaching was confirmed in seven anemone species (with anecdotal reports of bleaching in the other three species) at 10 of 19 survey locations spanning the Indo-Pacific and Red Sea, indicating that anemone bleaching is taxonomically and geographically widespread. In total, bleaching was observed in 490 of the 13,896 surveyed anemones (3.5%); however, this percentage was much higher (19–100%) during five major bleaching events that were associated with periods of elevated water temperatures and coral bleaching. There was considerable spatial variation in anemone bleaching during most of these events, suggesting that certain sites and deeper waters might act as refuges. Susceptibility to bleaching varied between species, and in some species, bleaching caused reductions in size and abundance. Conclusions/Significance Anemones are long-lived with low natural mortality, which makes them particularly vulnerable to predicted increases in severity and frequency of bleaching events. Population viability will be severely compromised if anemones and their symbionts cannot acclimate or adapt to rising sea temperatures. Anemone bleaching also has negative effects to other species, particularly those that have an obligate relationship with anemones. These effects include reductions in abundance and reproductive output of anemonefishes. Therefore, the future of these iconic and commercially valuable coral reef fishes is inextricably linked to the ability of host anemones to cope with rising sea temperatures associated with climate change. PMID:23951056

Coral Bleaching Assessment Through Remote Sensing and Integrated Citizen Science (CoralBASICS): Engaging Dive Instructors on Reef Characterization in Southwest, Puerto Rico Coupled with the Analysis of Water Quality Using NASA Earth Observations

NASA Astrophysics Data System (ADS)

Torres-Perez, J. L.; Armstrong, R.; Detres, Y.; Aragones-Fred, C.; Melendez, J.

2017-12-01

As recurrences of extreme sea water thermal events increase with climate change, the need for continuous monitoring of coral reefs becomes even more evident. Enabling properly trained members from the local communities to actively participate in scientific programs/research projects, provides for such monitoring at little cost once the citizens are properly trained and committed. Further, the possibility of obtaining high temporal resolution data with citizen scientists can provide for new venues to answer questions that may not be answered with traditional research approaches. The CoralBASICS project engages members of the local diving industry in Puerto Rico on the assessment of coastal water quality and the status of Puerto Rico's coral reefs in an age of climate change and in particular, an increase in the frequency and magnitude of coral bleaching events. The project complements remote sensing data with community-based field assessments strictly supervised by the PI's. The study focuses on training citizen scientists (dive instructors) on the collection of benthic information related to the state of coral reefs using the Reef Check (fish and invertebrates ID and substrate composition) and video transects methodologies, monitoring of coral bleaching events, and collecting of water quality data using a smartphone ocean color application. The data collected by citizen scientists complements the validation of Landsat-8 (OLI) imagery for water quality assessment. At the same time, researchers from the University of Puerto Rico conduct field assessment of the bio-optical properties of waters surrounding the coral reef study areas. Dive instructors have been collecting benthic and water quality data for the past 4 months. Initial analysis using the Coral Point Count with excel extension (CPCe) software showed a dominance of gorgonians at most sites (up to 32.8%) with hard coral cover ranging between 5.5-13.2% of the hard substrates. No coral diseases or bleaching have been observed so far. However, nutrient indicator algae were observed at most sites. As such, the project provides for technology and data transfer between the academia, government (NASA), researchers and local members of the community for a better assessment of environmental conditions affecting important coral reef areas in PR.

40 CFR 63.445 - Standards for the bleaching system.

Code of Federal Regulations, 2010 CFR

2010-07-01

... process using secondary or non-wood fibers, that use chlorine dioxide. (b) The equipment at each bleaching... system. (a) Each bleaching system that does not use any chlorine or chlorinated compounds for bleaching... systems shall meet all the provisions of this section: (1) Bleaching systems that use chlorine; (2...

40 CFR 63.445 - Standards for the bleaching system.

Code of Federal Regulations, 2011 CFR

2011-07-01

... process using secondary or non-wood fibers, that use chlorine dioxide. (b) The equipment at each bleaching... system. (a) Each bleaching system that does not use any chlorine or chlorinated compounds for bleaching... systems shall meet all the provisions of this section: (1) Bleaching systems that use chlorine; (2...

Effects of green tea on the shear bond strength of orthodontic brackets after in-office vital bleaching.

PubMed

Berger, Sandrine Bittencourt; Guiraldo, Ricardo Danil; Lopes, Murilo Baena; Oltramari-Navarro, Paula Vanessa; Fernandes, Thais Maria; Schwertner, Renata de Castro Alves; Ursi, Wagner José Silva

2016-01-01

The application of bleaching agents before placement of resin-bonded fixed appliances significantly, but temporarily, reduces bond strength to tooth structure. Antioxidants have been studied as a means to remove residual oxygen that compromises bonding to bleached enamel. This in vitro study evaluated whether green tea (GT) could restore the shear bond strength between bonded orthodontic brackets and bleached enamel. Six experimental groups were compared: group 1, no bleaching plus bracket bonding (positive control); group 2, bleaching with 35% hydrogen peroxide (HP) plus bracket bonding (negative control); group 3, 35% HP plus 10% sodium ascorbate (SA) plus bracket bonding; group 4, 35% HP plus 10% GT plus bracket bonding; group 5, no bleaching plus 10% SA plus bracket bonding; group 6, no bleaching plus 10% GT plus bracket bonding. Results suggested that GT, like SA, may be beneficial for bracket bonding immediately after bleaching.

Differential Response of Coral Assemblages to Thermal Stress Underscores the Complexity in Predicting Bleaching Susceptibility.

PubMed

Chou, Loke Ming; Toh, Tai Chong; Toh, Kok Ben; Ng, Chin Soon Lionel; Cabaitan, Patrick; Tun, Karenne; Goh, Eugene; Afiq-Rosli, Lutfi; Taira, Daisuke; Du, Rosa Celia Poquita; Loke, Hai Xin; Khalis, Aizat; Li, Jinghan; Song, Tiancheng

2016-01-01

Coral bleaching events have been predicted to occur more frequently in the coming decades with global warming. The susceptibility of corals to bleaching during thermal stress episodes is dependent on many factors and an understanding of these underlying drivers is crucial for conservation management. In 2013, a mild bleaching episode ensued in response to elevated sea temperature on the sediment-burdened reefs in Singapore. Surveys of seven sites highlighted variable bleaching susceptibility among coral genera-Pachyseris and Podabacia were the most impacted (31% of colonies of both genera bleached). The most susceptible genera such as Acropora and Pocillopora, which were expected to bleach, did not. Susceptibility varied between less than 6% and more than 11% of the corals bleached, at four and three sites respectively. Analysis of four of the most bleached genera revealed that a statistical model that included a combination of the factors (genus, colony size and site) provided a better explanation of the observed bleaching patterns than any single factor alone. This underscored the complexity in predicting the coral susceptibility to future thermal stress events and the importance of monitoring coral bleaching episodes to facilitate more effective management of coral reefs under climate change.

Differential Response of Coral Assemblages to Thermal Stress Underscores the Complexity in Predicting Bleaching Susceptibility

PubMed Central

Toh, Kok Ben; Ng, Chin Soon Lionel; Cabaitan, Patrick; Tun, Karenne; Goh, Eugene; Afiq-Rosli, Lutfi; Taira, Daisuke; Du, Rosa Celia Poquita; Loke, Hai Xin; Khalis, Aizat; Li, Jinghan; Song, Tiancheng

2016-01-01

Coral bleaching events have been predicted to occur more frequently in the coming decades with global warming. The susceptibility of corals to bleaching during thermal stress episodes is dependent on many factors and an understanding of these underlying drivers is crucial for conservation management. In 2013, a mild bleaching episode ensued in response to elevated sea temperature on the sediment-burdened reefs in Singapore. Surveys of seven sites highlighted variable bleaching susceptibility among coral genera–Pachyseris and Podabacia were the most impacted (31% of colonies of both genera bleached). The most susceptible genera such as Acropora and Pocillopora, which were expected to bleach, did not. Susceptibility varied between less than 6% and more than 11% of the corals bleached, at four and three sites respectively. Analysis of four of the most bleached genera revealed that a statistical model that included a combination of the factors (genus, colony size and site) provided a better explanation of the observed bleaching patterns than any single factor alone. This underscored the complexity in predicting the coral susceptibility to future thermal stress events and the importance of monitoring coral bleaching episodes to facilitate more effective management of coral reefs under climate change. PMID:27438593

Evaluation of the Diode laser (810nm, 980 nm) on color change of teeth after external bleaching

PubMed Central

Kiomars, Nazanin; Azarpour, Pouneh; Mirzaei, Mansooreh; Hashemi kamangar, Sedighe Sadat; Kharazifard, Mohammad Javad

2016-01-01

Subject and aim: The aim of this study was to evaluate the efficiency of diode laser-activated bleaching systems for color change of teeth. Materials & Methods: 40 premolars with intact enamel surfaces were selected for five external bleaching protocols (n=8). Two different wavelengths of diode laser (810 and 980 nm) with two different hydrogen peroxide concentrations (30% and 46%) were selected for laser bleaching. Group 1 received bleaching (Heydent- Germany) with a 810 nm diode laser; Group 2 received bleaching (Heydent- Germany) with a 980 nm diode laser; Group 3 received bleaching (laser white*20- Biolase) with a 810 nm diode laser; Group 4 received bleaching (laser white*20- Biolase) with a 980 nm diode laser, with an output power of 1.5 W, in continuous wave (cw) mode for each irradiation. Group 5 as control group received 40% hydrogen peroxide (Opalescence Boost, Ultradent-USA) with no light activation. The color of teeth was scored at baseline and 1 week after bleaching with spectrophotometer. Color change data on the CIEL*a*b* system were analyzed statistically by the one-way ANOVA and Tukey's HSD test. Results: All the bleaching techniques resulted in shade change. According to ΔE values, all techniques were effective to bleach the teeth (ΔE ≥ 3). Statistically significant differences were detected among bleaching protocols (p=0.06). Regarding shade change values expressed as ΔL*, Δa*, Δb*, ΔE*, laser bleached groups were no statistically different with each other (p>0.05). Conclusion: Bleaching with different wavelengths of diode laser resulted in the same results. PMID:28765671

Evaluation of the Diode laser (810nm, 980 nm) on color change of teeth after external bleaching.

PubMed

Kiomars, Nazanin; Azarpour, Pouneh; Mirzaei, Mansooreh; Hashemi Kamangar, Sedighe Sadat; Kharazifard, Mohammad Javad; Chiniforush, Nasim

2016-12-30

Subject and aim: The aim of this study was to evaluate the efficiency of diode laser-activated bleaching systems for color change of teeth. Materials & Methods: 40 premolars with intact enamel surfaces were selected for five external bleaching protocols (n=8). Two different wavelengths of diode laser (810 and 980 nm) with two different hydrogen peroxide concentrations (30% and 46%) were selected for laser bleaching. Group 1 received bleaching (Heydent- Germany) with a 810 nm diode laser; Group 2 received bleaching (Heydent- Germany) with a 980 nm diode laser; Group 3 received bleaching (laser white*20- Biolase) with a 810 nm diode laser; Group 4 received bleaching (laser white*20- Biolase) with a 980 nm diode laser, with an output power of 1.5 W, in continuous wave (cw) mode for each irradiation. Group 5 as control group received 40% hydrogen peroxide (Opalescence Boost, Ultradent-USA) with no light activation. The color of teeth was scored at baseline and 1 week after bleaching with spectrophotometer. Color change data on the CIEL*a*b* system were analyzed statistically by the one-way ANOVA and Tukey's HSD test. Results: All the bleaching techniques resulted in shade change. According to ΔE values, all techniques were effective to bleach the teeth (ΔE ≥ 3). Statistically significant differences were detected among bleaching protocols (p=0.06). Regarding shade change values expressed as ΔL*, Δa*, Δb*, ΔE*, laser bleached groups were no statistically different with each other (p>0.05). Conclusion: Bleaching with different wavelengths of diode laser resulted in the same results.

Annual coral bleaching and the long-term recovery capacity of coral

PubMed Central

Schoepf, Verena; Grottoli, Andréa G.; Levas, Stephen J.; Aschaffenburg, Matthew D.; Baumann, Justin H.; Matsui, Yohei; Warner, Mark E.

2015-01-01

Mass bleaching events are predicted to occur annually later this century. Nevertheless, it remains unknown whether corals will be able to recover between annual bleaching events. Using a combined tank and field experiment, we simulated annual bleaching by exposing three Caribbean coral species (Porites divaricata, Porites astreoides and Orbicella faveolata) to elevated temperatures for 2.5 weeks in 2 consecutive years. The impact of annual bleaching stress on chlorophyll a, energy reserves, calcification, and tissue C and N isotopes was assessed immediately after the second bleaching and after both short- and long-term recovery on the reef (1.5 and 11 months, respectively). While P. divaricata and O. faveolata were able to recover from repeat bleaching within 1 year, P. astreoides experienced cumulative damage that prevented full recovery within this time frame, suggesting that repeat bleaching had diminished its recovery capacity. Specifically, P. astreoides was not able to recover protein and carbohydrate concentrations. As energy reserves promote bleaching resistance, failure to recover from annual bleaching within 1 year will likely result in the future demise of heat-sensitive coral species. PMID:26582020

Annual coral bleaching and the long-term recovery capacity of coral.

PubMed

Schoepf, Verena; Grottoli, Andréa G; Levas, Stephen J; Aschaffenburg, Matthew D; Baumann, Justin H; Matsui, Yohei; Warner, Mark E

2015-11-22

Mass bleaching events are predicted to occur annually later this century. Nevertheless, it remains unknown whether corals will be able to recover between annual bleaching events. Using a combined tank and field experiment, we simulated annual bleaching by exposing three Caribbean coral species (Porites divaricata, Porites astreoides and Orbicella faveolata) to elevated temperatures for 2.5 weeks in 2 consecutive years. The impact of annual bleaching stress on chlorophyll a, energy reserves, calcification, and tissue C and N isotopes was assessed immediately after the second bleaching and after both short- and long-term recovery on the reef (1.5 and 11 months, respectively). While P. divaricata and O. faveolata were able to recover from repeat bleaching within 1 year, P. astreoides experienced cumulative damage that prevented full recovery within this time frame, suggesting that repeat bleaching had diminished its recovery capacity. Specifically, P. astreoides was not able to recover protein and carbohydrate concentrations. As energy reserves promote bleaching resistance, failure to recover from annual bleaching within 1 year will likely result in the future demise of heat-sensitive coral species. © 2015 The Author(s).

Natural Zeolite Sample and Investigation Its Use in Oil Bleaching Sector

NASA Astrophysics Data System (ADS)

Bilgin, Oyku

2017-12-01

In the sector of oil bleaching, the stored raw oil is subjected to physical and chemical methods such as degumming, neutralization, bleaching, deodorization and winterization. In the process of oil bleaching, the selection of correct bleaching earth in accordance with oil characteristics matters so much. Bleaching earth is an inorganic product used in removing impurities being available within the structures of vegetable, animal oil (sunflower, soya, corn, palm, tallow, rapeseed, fish oils…etc.) and fatty acids, mineral oils (glycerine, paraffin, mineral motor oils. etc.) with the adsorption process. The factors such as low cost of oil bleaching earth, low ratio of oil retaining, high bleaching capacity in spite of using them in small amounts, filter’s delayed blocking by the earth and non-increase of the free acidity of the oil should be taken into consideration. Bleaching earths are processed with some acids in order to widen their surface areas. During this process, a certain amount of acid is left within oil bleaching earths even if it is very little. These acids also increase oil’s acidity by oxidizing oil in the course of bleaching process. In this study, zeolite sample taken from Manisa -Demirci region was used. Following the processes of crushing and sieving, zeolite sample was subjected to chemical analyses according to their grain thickness, microscopic examination, the analyses of XRD and cation exchange capacity and their ore characteristics were determined. Afterwards, it was searched whether zeolite sample has oil bleaching ability or not or whether it can be used as oil bleaching earth or not.

Response of coral assemblages to thermal stress: are bleaching intensity and spatial patterns consistent between events?

PubMed

Penin, Lucie; Vidal-Dupiol, Jeremie; Adjeroud, Mehdi

2013-06-01

Mass bleaching events resulting in coral mortality are among the greatest threats to coral reefs, and are projected to increase in frequency and intensity with global warming. Achieving a better understanding of the consistency of the response of coral assemblages to thermal stress, both spatially and temporally, is essential to determine which reefs are more able to tolerate climate change. We compared variations in spatial and taxonomic patterns between two bleaching events at the scale of an island (Moorea Island, French Polynesia). Despite similar thermal stress and light conditions, bleaching intensity was significantly lower in 2007 (approximately 37 % of colonies showed signs of bleaching) than in 2002, when 55 % of the colonies bleached. Variations in the spatial patterns of bleaching intensity were consistent between the two events. Among nine sampling stations at three locations and three depths, the stations at which the bleaching response was lowest in 2002 were those that showed the lowest levels of bleaching in 2007. The taxonomic patterns of susceptibility to bleaching were also consistent between the two events. These findings have important implications for conservation because they indicate that corals are capable of acclimatization and/or adaptation and that, even at small spatial scales, some areas are consistently more susceptible to bleaching than others.

Changes in coral-associated microbial communities during a bleaching event.

PubMed

Bourne, David; Iida, Yuki; Uthicke, Sven; Smith-Keune, Carolyn

2008-04-01

Environmental stressors such as increased sea surface temperatures are well-known for contributing to coral bleaching; however, the effect of increased temperatures and subsequent bleaching on coral-associated microbial communities is poorly understood. Colonies of the hard coral Acropora millepora were tagged on a reef flat off Magnetic Island (Great Barrier Reef) and surveyed over 2.5 years, which included a severe bleaching event in January/February 2002. Daily average water temperatures exceeded the previous 10-year average by more than 1 degrees C for extended periods with field-based visual surveys recording all tagged colonies displaying signs of bleaching. During the bleaching period, direct counts of coral zooxanthellae densities decreased by approximately 64%, before recovery to pre-bleaching levels after the thermal stress event. A subset of three tagged coral colonies were sampled through the bleaching event and changes in the microbial community elucidated. Denaturing gradient gel electrophoresis (DGGE) analysis demonstrated conserved bacterial banding profiles between the three coral colonies, confirming previous studies highlighting specific microbial associations. As coral colonies bleached, the microbial community shifted and redundancy analysis (RDA) of DGGE banding patterns revealed a correlation of increasing temperature with the appearance of Vibrio-affiliated sequences. Interestingly, this shift to a Vibrio-dominated community commenced prior to visual signs of bleaching. Clone libraries hybridized with Vibrio-specific oligonucleotide probes confirmed an increase in the fraction of Vibrio-affiliated clones during the bleaching period. Post bleaching, the coral microbial associations again shifted, returning to a profile similar to the fingerprints prior to bleaching. This provided further evidence for corals selecting and shaping their microbial partners. For non-bleached samples, a close association with Spongiobacter-related sequences were revealed by both clone libraries and DGGE profiling. Despite Vibrio species being previously implicated in bleaching of specific coral species, it is unsure if the relative increase in retrieved Vibrio sequences is due to bacterial infection or an opportunistic response to compromised health and changing environmental parameters of the coral host. This study provides the first molecular-based study demonstrating changes in coral-associated bacterial assemblages during a bleaching event on a natural reef system.

Influence of photo- and thermal bleaching on pre-irradiation low water peak single mode fibers

NASA Astrophysics Data System (ADS)

Yin, Jianchong; Wen, Jianxiang; Luo, Wenyun; Xiao, Zhongyin; Chen, Zhenyi; Wang, Tingyun

2011-12-01

Reducing the radiation-induced transmission loss in low water peak single mode fiber (LWP SMF) has been investigated by using photo-bleaching method with 980nm pump light source and using thermal-bleaching method with temperature control system. The results show that the radiation-induced loss of pre-irradiation optical fiber can be reduced effectively with the help of photo-bleaching or thermal-bleaching. Although the effort of photo-bleaching is not as significant as thermal-bleaching, by using photo-bleaching method, the loss of fiber caused by radiation-induced defects can be reduced best up to 49% at 1310nm and 28% at 1550nm in low pre-irradiation condition, the coating of the fiber are not destroyed, and the rehabilitating time is just several hours, while self-annealing usually costs months' time. What's more, the typical high power LASER for photo-bleaching can be 980nm pump Laser Diode, which is very accessible.

The effects of habitat on coral bleaching responses in Kenya.

PubMed

Grimsditch, Gabriel; Mwaura, Jelvas M; Kilonzo, Joseph; Amiyo, Nassir

2010-06-01

This study examines the bleaching responses of scleractinian corals at four sites in Kenya (Kanamai, Vipingo, Mombasa and Nyali) representing two distinct lagoon habitats (relatively shallow and relatively deep). Bleaching incidence was monitored for the whole coral community, while zooxanthellae densities and chlorophyll levels were monitored for target species (Pocillopora damicornis, Porites lutea, and Porites cylindrica) during a non-bleaching year (2006) and a year of mild-bleaching (2007). Differences in bleaching responses between habitats were observed, with shallower sites Kanamai and Vipingo exhibiting lower bleaching incidence than deeper sites Nyali and Mombasa. These shallower lagoons display more fluctuating thermal and light environments than the deeper sites, suggesting that corals in the shallower lagoons have acclimatized and/or adapted to the fluctuating environmental conditions they endure on a daily basis and have become more resistant to bleaching stress. In deeper sites that did exhibit higher bleaching (Mombasa and Nyali), it was found that coral recovery occurred more quickly in the protected area than in the non-protected area.

The effects of coral bleaching on settlement preferences and growth of juvenile butterflyfishes.

PubMed

Cole, A J; Lawton, R J; Pisapia, C; Pratchett, M S

2014-07-01

Coral bleaching and associated mortality is an increasingly prominent threat to coral reef ecosystems. Although the effects of bleaching-induced coral mortality on reef fishes have been well demonstrated, corals can remain bleached for several weeks prior to recovery or death and little is known about how bleaching affects resident fishes during this time period. This study compared growth rates of two species of juvenile butterflyfishes (Chaetodon aureofasciatus and Chaetodon lunulatus) that were restricted to feeding upon either bleached or healthy coral tissue of Acropora spathulata or Pocillopora damicornis. Coral condition (bleached vs. unbleached) had no significant effects on changes in total length or weight over a 23-day period. Likewise, in a habitat choice experiment, juvenile butterflyfishes did not discriminate between healthy and bleached corals, but actively avoided using recently dead colonies. These results indicate that juvenile coral-feeding fishes are relatively robust to short term effects of bleaching events, provided that the corals do recover. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

BioNetCAD: design, simulation and experimental validation of synthetic biochemical networks

PubMed Central

Rialle, Stéphanie; Felicori, Liza; Dias-Lopes, Camila; Pérès, Sabine; El Atia, Sanaâ; Thierry, Alain R.; Amar, Patrick; Molina, Franck

2010-01-01

Motivation: Synthetic biology studies how to design and construct biological systems with functions that do not exist in nature. Biochemical networks, although easier to control, have been used less frequently than genetic networks as a base to build a synthetic system. To date, no clear engineering principles exist to design such cell-free biochemical networks. Results: We describe a methodology for the construction of synthetic biochemical networks based on three main steps: design, simulation and experimental validation. We developed BioNetCAD to help users to go through these steps. BioNetCAD allows designing abstract networks that can be implemented thanks to CompuBioTicDB, a database of parts for synthetic biology. BioNetCAD enables also simulations with the HSim software and the classical Ordinary Differential Equations (ODE). We demonstrate with a case study that BioNetCAD can rationalize and reduce further experimental validation during the construction of a biochemical network. Availability and implementation: BioNetCAD is freely available at http://www.sysdiag.cnrs.fr/BioNetCAD. It is implemented in Java and supported on MS Windows. CompuBioTicDB is freely accessible at http://compubiotic.sysdiag.cnrs.fr/ Contact: stephanie.rialle@sysdiag.cnrs.fr; franck.molina@sysdiag.cnrs.fr Supplementary information: Supplementary data are available at Bioinformatics online. PMID:20628073

Symbiotic immuno-suppression: is disease susceptibility the price of bleaching resistance?

PubMed

Merselis, Daniel G; Lirman, Diego; Rodriguez-Lanetty, Mauricio

2018-01-01

Accelerating anthropogenic climate change threatens to destroy coral reefs worldwide through the processes of bleaching and disease. These major contributors to coral mortality are both closely linked with thermal stress intensified by anthropogenic climate change. Disease outbreaks typically follow bleaching events, but a direct positive linkage between bleaching and disease has been debated. By tracking 152 individual coral ramets through the 2014 mass bleaching in a South Florida coral restoration nursery, we revealed a highly significant negative correlation between bleaching and disease in the Caribbean staghorn coral, Acropora cervicornis . To explain these results, we propose a mechanism for transient immunological protection through coral bleaching: removal of Symbiodinium during bleaching may also temporarily eliminate suppressive symbiont modulation of host immunological function. We contextualize this hypothesis within an ecological perspective in order to generate testable predictions for future investigation.

Symbiotic immuno-suppression: is disease susceptibility the price of bleaching resistance?

PubMed Central

Merselis, Daniel G.; Lirman, Diego

2018-01-01

Accelerating anthropogenic climate change threatens to destroy coral reefs worldwide through the processes of bleaching and disease. These major contributors to coral mortality are both closely linked with thermal stress intensified by anthropogenic climate change. Disease outbreaks typically follow bleaching events, but a direct positive linkage between bleaching and disease has been debated. By tracking 152 individual coral ramets through the 2014 mass bleaching in a South Florida coral restoration nursery, we revealed a highly significant negative correlation between bleaching and disease in the Caribbean staghorn coral, Acropora cervicornis. To explain these results, we propose a mechanism for transient immunological protection through coral bleaching: removal of Symbiodinium during bleaching may also temporarily eliminate suppressive symbiont modulation of host immunological function. We contextualize this hypothesis within an ecological perspective in order to generate testable predictions for future investigation. PMID:29682405

Real-time local experimental monitoring of the bleaching process.

PubMed

Rakic, Mario; Klaric, Eva; Sever, Ivan; Rakic, Iva Srut; Pichler, Goran; Tarle, Zrinka

2015-04-01

The purpose of this article was to investigate a new setup for tooth bleaching and monitoring of the same process in real time, so to prevent overbleaching and related sideeffects of the bleaching procedure. So far, known bleaching procedures cannot simultaneously monitor and perform the bleaching process or provide any local control over bleaching. The experimental setup was developed at the Institute of Physics, Zagreb. The setup consists of a camera, a controller, and optical fibers. The bleaching was performed with 25% hydrogen peroxide activated by ultraviolet light diodes, and the light for monitoring was emitted by white light diodes. The collected light was analyzed using a red-green-blue (RGB) index. A K-type thermocouple was used for temperature measurements. Pastilles made from hydroxylapatite powder as well as human teeth served as experimental objects. Optimal bleaching time substantially varied among differently stained specimens. To reach reference color (A1, Chromascop shade guide), measured as an RGB index, bleaching time for pastilles ranged from 8 to >20 min, whereas for teeth it ranged from 3.5 to >20 min. The reflected light intensity of each R, G, and B component at the end of bleaching process (after 20 min) had increased up to 56% of the baseline intensity. The presented experimental setup provides essential information about when to stop the bleaching process to achieve the desired optical results so that the bleaching process can be completely responsive to the characteristics of every individual, leading to more satisfying results.

Coral community response to bleaching on a highly disturbed reef

PubMed Central

Guest, J. R.; Low, J.; Tun, K.; Wilson, B.; Ng, C.; Raingeard, D.; Ulstrup, K. E.; Tanzil, J. T. I.; Todd, P. A.; Toh, T. C.; McDougald, D.; Chou, L. M.; Steinberg, P. D.

2016-01-01

While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress. PMID:26876092

A Study for Tooth Bleaching via Carbamide Peroxide-Loaded Hollow Calcium Phosphate Spheres.

PubMed

Qin, Tao; Mellgren, Torbjörn; Jefferies, Steven; Xia, Wei; Engqvist, Håkan

2016-12-26

The objective of this study was to investigate if a prolonged bleaching effect of carbamide peroxide-loaded hollow calcium phosphate spheres (HCPS) can be achieved. HCPS was synthesized via a hydrothermal reaction method. Carbamide peroxide (CP) was-loaded into HCPS by mixing with distilled water as solvent. We developed two bleaching gels containing CP-loaded HCPS: one gel with low HP concentration as at-home bleaching gel, and one with high HP concentration as in-office gel. Their bleaching effects on stained human permanent posterior teeth were investigated by measuring the color difference before and after bleaching. The effect of gels on rhodamine B degradation was also studied. To investigate the potential effect of remineralization of using HCPS, bleached teeth were soaked in phosphate buffer solution (PBS) containing calcium and magnesium ions. Both bleaching gels had a prolonged whitening effect, and showed a strong ability to degrade rhodamine B. After soaking in PBS for 3 days, remineralization was observed at the sites where HCPS attached to the teeth surface. CP-loaded HCPS could prolong the HP release behavior and improve the bleaching effect. HCPS was effective in increasing the whitening effect of carbamide peroxide and improving remineralization after bleaching process.

Coral community response to bleaching on a highly disturbed reef.

PubMed

Guest, J R; Low, J; Tun, K; Wilson, B; Ng, C; Raingeard, D; Ulstrup, K E; Tanzil, J T I; Todd, P A; Toh, T C; McDougald, D; Chou, L M; Steinberg, P D

2016-02-15

While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress.

Coral community response to bleaching on a highly disturbed reef

NASA Astrophysics Data System (ADS)

Guest, J. R.; Low, J.; Tun, K.; Wilson, B.; Ng, C.; Raingeard, D.; Ulstrup, K. E.; Tanzil, J. T. I.; Todd, P. A.; Toh, T. C.; McDougald, D.; Chou, L. M.; Steinberg, P. D.

2016-02-01

While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress.

The influence of bleaching agent and temperature on bleaching efficacy and volatile components of fluid whey and whey retentate.

PubMed

Fox, A J; Smith, T J; Gerard, P D; Drake, M A

2013-10-01

Fluid whey or retentate are often bleached to remove residual annatto Cheddar cheese colorant, and this process causes off-flavors in dried whey proteins. This study determined the impact of temperature and bleaching agent on bleaching efficacy and volatile components in fluid whey and fluid whey retentate. Freshly manufactured liquid whey (6.7% solids) or concentrated whey protein (retentate) (12% solids, 80% protein) were bleached using benzoyl peroxide (BP) at 100 mg/kg (w/w) or hydrogen peroxide (HP) at 250 mg/kg (w/w) at 5 °C for 16 h or 50 °CC for 1 h. Unbleached controls were subjected to a similar temperature profile. The experiment was replicated three times. Annatto destruction (bleaching efficacy) among treatments was compared, and volatile compounds were extracted and separated using solid phase microextraction gas chromatography mass spectrometry (SPME GC-MS). Bleaching efficacy of BP was higher than HP (P < 0.05) for fluid whey at both 5 and 50 °C. HP bleaching efficacy was increased in retentate compared to liquid whey (P < 0.05). In whey retentate, there was no difference between bleaching with HP or BP at 50 or 5 °C (P > 0.05). Retentate bleached with HP at either temperature had higher relative abundances of pentanal, hexanal, heptanal, and octanal than BP bleached retentate (P < 0.05). Liquid wheys generally had lower concentrations of selected volatiles compared to retentates. These results suggest that the highest bleaching efficacy (within the parameters evaluated) in liquid whey is achieved using BP at 5 or 50 °C and at 50 °C with HP or BP in whey protein retentate. © 2013 Institute of Food Technologists®

Does the Use of a "Walking Bleaching" Technique Increase Bone Resorption Markers?

PubMed

Bersezio, C; Vildósola, P; Sáez, M; Sánchez, F; Vernal, R; Oliveira, O B; Jorquera, G; Basualdo, J; Loguercio, A; Fernández, E

This randomized clinical trial evaluated the effect of 35% hydrogen peroxide in comparison with 37% carbamide peroxide in a nonvital bleaching technique of "walking bleaching" (four sessions of treatment) on periodontal markers: nuclear factor kappa B-ligand (RANK-L-process of root resorption marker) and interleukin 1β (IL-1β-inflammatory response marker). Fifty volunteers presenting with discoloration of nonvital teeth and endodontic treatment in good condition participated. Fifty teeth were randomly divided into two study groups according to bleaching gel: HP = 35% hydrogen peroxide (n=25) and 37% carbamide peroxide (n=25). Nonvital bleaching was performed with a walking bleaching technique consisting of four sessions of bleach application. Gingival crevicular fluid samples were taken in order to quantify the RANK-L and IL-1β levels by enzyme-linked immunosorbent assay. Samples were obtained from six periodontal sites for each bleached tooth: three vestibular and three palatine (mesial, middle, and distal) at seven time periods: baseline, after each of the four sessions of nonvital bleaching, at one week, and at one month after nonvital bleaching. Tooth color variations were analyzed in each session by VITA Bleachedguide 3D-MASTER (ΔSGU). Significant increments in the RANK-L and IL-1β levels were detected in each evaluated time compared with baseline ( p<0.05); however, no differences were detected between hydrogen peroxide and carbamide peroxide on increments of the biomarkers studied. The change of color was effective for both nonvital bleaching therapies ( p<0.05). Nonvital bleaching induced a significant increment in the RANK-L and IL-1β levels in periodontal tissues around bleached, nonvital teeth.

Analysis of the diffusion of Ras2 in Saccharomyces cerevisiae using fluorescence recovery after photobleaching

NASA Astrophysics Data System (ADS)

Vinnakota, Kalyan C.; Mitchell, David A.; Deschenes, Robert J.; Wakatsuki, Tetsuro; Beard, Daniel A.

2010-06-01

Binding, lateral diffusion and exchange are fundamental dynamic processes involved in protein association with cellular membranes. In this study, we developed numerical simulations of lateral diffusion and exchange of fluorophores in membranes with arbitrary bleach geometry and exchange of the membrane-localized fluorophore with the cytosol during fluorescence recovery after photobleaching (FRAP) experiments. The model simulations were used to design FRAP experiments with varying bleach region sizes on plasma membrane-localized wild-type GFP-Ras2 with a dual lipid anchor and mutant GFP-Ras2C318S with a single lipid anchor in live yeast cells to investigate diffusional mobility and the presence of any exchange processes operating in the time scale of our experiments. Model parameters estimated using data from FRAP experiments with a 1 µm × 1 µm bleach region-of-interest (ROI) and a 0.5 µm × 0.5 µm bleach ROI showed that GFP-Ras2, single or dual lipid modified, diffuses as single species with no evidence of exchange with a cytoplasmic pool. This is the first report of Ras2 mobility in the yeast plasma membrane. The methods developed in this study are generally applicable for studying diffusion and exchange of membrane-associated fluorophores using FRAP on commercial confocal laser scanning microscopes.

Incorporating adaptive responses into future projections of coral bleaching.

PubMed

Logan, Cheryl A; Dunne, John P; Eakin, C Mark; Donner, Simon D

2014-01-01

Climate warming threatens to increase mass coral bleaching events, and several studies have projected the demise of tropical coral reefs this century. However, recent evidence indicates corals may be able to respond to thermal stress though adaptive processes (e.g., genetic adaptation, acclimatization, and symbiont shuffling). How these mechanisms might influence warming-induced bleaching remains largely unknown. This study compared how different adaptive processes could affect coral bleaching projections. We used the latest bias-corrected global sea surface temperature (SST) output from the NOAA/GFDL Earth System Model 2 (ESM2M) for the preindustrial period through 2100 to project coral bleaching trajectories. Initial results showed that, in the absence of adaptive processes, application of a preindustrial climatology to the NOAA Coral Reef Watch bleaching prediction method overpredicts the present-day bleaching frequency. This suggests that corals may have already responded adaptively to some warming over the industrial period. We then modified the prediction method so that the bleaching threshold either permanently increased in response to thermal history (e.g., simulating directional genetic selection) or temporarily increased for 2-10 years in response to a bleaching event (e.g., simulating symbiont shuffling). A bleaching threshold that changes relative to the preceding 60 years of thermal history reduced the frequency of mass bleaching events by 20-80% compared with the 'no adaptive response' prediction model by 2100, depending on the emissions scenario. When both types of adaptive responses were applied, up to 14% more reef cells avoided high-frequency bleaching by 2100. However, temporary increases in bleaching thresholds alone only delayed the occurrence of high-frequency bleaching by ca. 10 years in all but the lowest emissions scenario. Future research should test the rate and limit of different adaptive responses for coral species across latitudes and ocean basins to determine if and how much corals can respond to increasing thermal stress.

Bacteria are not the primary cause of bleaching in the Mediterranean coral Oculina patagonica.

PubMed

Ainsworth, T D; Fine, M; Roff, G; Hoegh-Guldberg, O

2008-01-01

Coral bleaching occurs when the endosymbiosis between corals and their symbionts disintegrates during stress. Mass coral bleaching events have increased over the past 20 years and are directly correlated with periods of warm sea temperatures. However, some hypotheses have suggested that reef-building corals bleach due to infection by bacterial pathogens. The 'Bacterial Bleaching' hypothesis is based on laboratory studies of the Mediterranean invading coral, Oculina patagonica, and has further generated conclusions such as the coral probiotic hypothesis and coral hologenome theory of evolution. We aimed to investigate the natural microbial ecology of O. patagonica during the annual bleaching using fluorescence in situ hybridization to map bacterial populations within the coral tissue layers, and found that the coral bleaches on the temperate rocky reefs of the Israeli coastline without the presence of Vibrio shiloi or bacterial penetration of its tissue layers. Bacterial communities were found associated with the endolithic layer of bleached coral regions, and a community dominance shift from an apparent cyanobacterial-dominated endolithic layer to an algal-dominated layer was found in bleached coral samples. While bacterial communities certainly play important roles in coral stasis and health, we suggest environmental stressors, such as those documented with reef-building corals, are the primary triggers leading to bleaching of O. patagonica and suggest that bacterial involvement in patterns of bleaching is that of opportunistic colonization.

Toxicity and efficiency study of plant extracts-based bleaching agents.

PubMed

Baldea, Ioana; Olteanu, Diana Elena; Filip, Adriana Gabriela; Cenariu, Mihai; Dudea, Diana; Tofan, Alina; Alb, Camelia; Moldovan, Marioara

2017-05-01

Tooth bleaching is one of the most required dental esthetic treatments. However, it can generate side effects like oral irritation, enamel alteration, tooth sensitivity, especially caused by hydrogen peroxide, the main bleaching component of the commercial products. Therefore, development of new tooth bleaching agents, based on natural products, with comparable esthetic results and lower side effects is needed. The aim of this study was to evaluate the biological effects and bleaching efficacy of four experimental bleaching agents, derived from fruit juices, against the commercially available Opalescence (Ultradent, USA). Organic acid composition of the gels was characterized by HPLC. Bleaching efficiency was tested by spectrophotometry on composite restorative materials. Biological testing was done in vitro, on human fibroblasts. Cells were exposed to dilutions of the bleaching gel-conditioned medium. Viability was measured by MTS, apoptosis by FACS-AnnexinV FITC/Propidium iodide, NF-kB activation by western blot, malondyaldehide, and superoxide dismutase activity by spectrophotometry. All gels exhibited physical stability and dental bleaching capabilities. Experimental gels induced significantly better viability and apoptosis rates, lower lipid peroxidation, and increased antioxidant defense, compared to Opalescence. The studied experimental gel formulations exhibited a good safety profile in vitro, as well as bleaching efficiency on restorative composite materials. These data open new possibilities for the use of new natural products in dental bleaching treatments that can insure significant esthetic results and lower side effects.

Clinical and patient reported outcomes of bleaching effectiveness.

PubMed

Klaric Sever, Eva; Budimir, Zrinka; Cerovac, Matea; Stambuk, Mario; Par, Matej; Negovetic Vranic, Dubravka; Tarle, Zrinka

2018-01-01

The objective of this study is to evaluate clinical and patient reported outcomes of different bleaching products. Thirty participants were randomly divided into three bleaching groups (n = 10). Bleaching was performed with high concentrations of hydrogen peroxide (HP) - Boost (40%) and Dash (30%), and with prefabricated splints Bite&White (6% HP). Tooth colour was measured before, immediately after, and 1 and 6 months after the bleaching by using classical shade guide and spectrophotometer. Tooth hypersensitivity was self-rated by patients on the Wong-Baker's face scale. Patient satisfaction was evaluated on a 7-point Likert-type scales that measured perceived performance and importance of different characteristics of bleaching treatment. All products were effective in teeth colour change (ΔE > 3.3), which was significantly higher for Boost (p = .016) and Dash (p = .024) than Bite&White treatment. Perception of hypersensitivity was the highest in Boost group, followed by Dash and Bite&White treatment. Most of the patients were satisfied with final tooth colour, length and comfort during treatment, but were dissatisfied with the stability of bleached tooth colour. Materials with the higher concentrations of bleaching agent demonstrated greater bleaching effectiveness than at-home bleaching product, but also a greater hypersensitivity. Lengthening the treatment process, but achieving a more stable tooth colour may improve the perceived value of a bleaching service.

[Effect of casein phosphopeptide-amorphouscalcium phosphate (CPP-ACP) treatment on the shear bond strength of orthodontic brackets after tooth bleaching].

PubMed

Lu, Jing; Ding, Xiao-jun; Yu, Xiao-ping; Gong, Yi-ming

2015-10-01

To evaluate the effect of casein phosphopeptide-amorphouscalcium phosphate (CPP-ACP) treatment on the shear bond strength of orthodontic brackets after tooth bleaching. One hundred extracted human premolars were randomly divided and treated according to 5 groups (n=20) : (1) no treatment; (2) 10% carbamide peroxide bleaching; (3) 38% hydrogen peroxide bleaching; (4)10% carbamide peroxide bleaching and CPP-ACP paste; (5)38% hydrogen peroxide bleaching and CPP-ACP paste. In all groups, the brackets were bonded using a conventional acid-etch and bond system (Transbond XT, 3M Unitek, Monrovia, Calif). The shear bond strength adhesive remnant index (ARI) of the brackets were determined and the data was analyzed by ANOVA and Bonferroni test using SPSS13.0 software package. The use of 10% carbamide peroxide and 38% hydrogen peroxide bleaching significantly decreased the shear bond strength of orthodontic brackets when compared with untreated group (P<0.05). After combination of tooth bleaching and CPP-ACP treatment, group 4 (10% carbamide peroxide bleaching + CPP-ACP) and group 5 (38% hydrogen peroxide bleaching + CPP-ACP) showed higher levels of shear bond strength than group 2 and 3; however, no significant difference was found (P>0.05). The ARI did not show any significant difference before and after CPP-ACP treatment. After tooth bleaching, CPP-ACP treatment have little influence on the shear bond strength of orthodontic brackets.

Global warming and recurrent mass bleaching of corals

NASA Astrophysics Data System (ADS)

Hughes, Terry P.; Kerry, James T.; Álvarez-Noriega, Mariana; Álvarez-Romero, Jorge G.; Anderson, Kristen D.; Baird, Andrew H.; Babcock, Russell C.; Beger, Maria; Bellwood, David R.; Berkelmans, Ray; Bridge, Tom C.; Butler, Ian R.; Byrne, Maria; Cantin, Neal E.; Comeau, Steeve; Connolly, Sean R.; Cumming, Graeme S.; Dalton, Steven J.; Diaz-Pulido, Guillermo; Eakin, C. Mark; Figueira, Will F.; Gilmour, James P.; Harrison, Hugo B.; Heron, Scott F.; Hoey, Andrew S.; Hobbs, Jean-Paul A.; Hoogenboom, Mia O.; Kennedy, Emma V.; Kuo, Chao-Yang; Lough, Janice M.; Lowe, Ryan J.; Liu, Gang; McCulloch, Malcolm T.; Malcolm, Hamish A.; McWilliam, Michael J.; Pandolfi, John M.; Pears, Rachel J.; Pratchett, Morgan S.; Schoepf, Verena; Simpson, Tristan; Skirving, William J.; Sommer, Brigitte; Torda, Gergely; Wachenfeld, David R.; Willis, Bette L.; Wilson, Shaun K.

2017-03-01

During 2015-2016, record temperatures triggered a pan-tropical episode of coral bleaching, the third global-scale event since mass bleaching was first documented in the 1980s. Here we examine how and why the severity of recurrent major bleaching events has varied at multiple scales, using aerial and underwater surveys of Australian reefs combined with satellite-derived sea surface temperatures. The distinctive geographic footprints of recurrent bleaching on the Great Barrier Reef in 1998, 2002 and 2016 were determined by the spatial pattern of sea temperatures in each year. Water quality and fishing pressure had minimal effect on the unprecedented bleaching in 2016, suggesting that local protection of reefs affords little or no resistance to extreme heat. Similarly, past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016. Consequently, immediate global action to curb future warming is essential to secure a future for coral reefs.

Bleaching and recovery of a phototrophic bioeroding sponge

NASA Astrophysics Data System (ADS)

Marlow, Joseph; Davy, Simon K.; Shaffer, Megan; Haris, Abdul; Bell, James J.

2018-06-01

In the Wakatobi region of Indonesia, a prolonged period of elevated water temperature in 2016 caused extensive coral bleaching and mortality. Unusually, bleaching was also observed in the bioeroding sponge Cliona aff. viridis, with affected sponges expelling 99% of their Symbiodinium. Bleaching surveys of C. aff. viridis were conducted 6 weeks apart, coinciding with a 0.8 °C drop in water temperature. Over this period, bleaching prevalence dropped from 73.9% (± 9.9 SE) to 25.7% (± 5.8 SE), and bleaching severity dropped from 25.95% (± 4.5 SE) to 11.54% (± 1.9 SE) of sponge tissue. Over the same period, monitored bleached sponges showed an 81% drop in bleaching severity, but also a 13% reduction in overall sponge size. Our results show that while the clionaid- Symbiodinium relationship is susceptible to break down under thermal stress, rapid recovery can occur, although incurring some partial host mortality.

Global warming and recurrent mass bleaching of corals.

PubMed

Hughes, Terry P; Kerry, James T; Álvarez-Noriega, Mariana; Álvarez-Romero, Jorge G; Anderson, Kristen D; Baird, Andrew H; Babcock, Russell C; Beger, Maria; Bellwood, David R; Berkelmans, Ray; Bridge, Tom C; Butler, Ian R; Byrne, Maria; Cantin, Neal E; Comeau, Steeve; Connolly, Sean R; Cumming, Graeme S; Dalton, Steven J; Diaz-Pulido, Guillermo; Eakin, C Mark; Figueira, Will F; Gilmour, James P; Harrison, Hugo B; Heron, Scott F; Hoey, Andrew S; Hobbs, Jean-Paul A; Hoogenboom, Mia O; Kennedy, Emma V; Kuo, Chao-Yang; Lough, Janice M; Lowe, Ryan J; Liu, Gang; McCulloch, Malcolm T; Malcolm, Hamish A; McWilliam, Michael J; Pandolfi, John M; Pears, Rachel J; Pratchett, Morgan S; Schoepf, Verena; Simpson, Tristan; Skirving, William J; Sommer, Brigitte; Torda, Gergely; Wachenfeld, David R; Willis, Bette L; Wilson, Shaun K

2017-03-15

During 2015-2016, record temperatures triggered a pan-tropical episode of coral bleaching, the third global-scale event since mass bleaching was first documented in the 1980s. Here we examine how and why the severity of recurrent major bleaching events has varied at multiple scales, using aerial and underwater surveys of Australian reefs combined with satellite-derived sea surface temperatures. The distinctive geographic footprints of recurrent bleaching on the Great Barrier Reef in 1998, 2002 and 2016 were determined by the spatial pattern of sea temperatures in each year. Water quality and fishing pressure had minimal effect on the unprecedented bleaching in 2016, suggesting that local protection of reefs affords little or no resistance to extreme heat. Similarly, past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016. Consequently, immediate global action to curb future warming is essential to secure a future for coral reefs.

Analysis of waste management issues arising from a field study evaluating decontamination of a biological agent from a building.

PubMed

Lemieux, P; Wood, J; Drake, J; Minamyer, S; Silvestri, E; Yund, C; Nichols, T; Ierardi, M; Amidan, B

2016-01-01

The Bio-response Operational Testing and Evaluation (BOTE) Project was a cross-government effort designed to operationally test and evaluate a response to a biological incident (release of Bacillus anthracis [Ba] spores, the causative agent for anthrax) from initial public health and law enforcement response through environmental remediation. The BOTE Project was designed to address site remediation after the release of a Ba simulant, Bacillus atrophaeus spp. globigii (Bg), within a facility, drawing upon recent advances in the biological sampling and decontamination areas. A key component of response to a biological contamination incident is the proper management of wastes and residues, which is woven throughout all response activities. Waste is generated throughout the response and includes items like sampling media packaging materials, discarded personal protective equipment, items removed from the facility either prior to or following decontamination, aqueous waste streams, and materials generated through the application of decontamination technologies. The amount of residual contaminating agent will impact the available disposal pathways and waste management costs. Waste management is an integral part of the decontamination process and should be included through "Pre-Incident" response planning. Overall, the pH-adjusted bleach decontamination process generated the most waste from the decontamination efforts, and fumigation with chlorine dioxide generated the least waste. A majority of the solid waste generated during pH-adjusted bleach decontamination was the nonporous surfaces that were removed, bagged, decontaminated ex situ, and treated as waste. The waste during the two fumigation rounds of the BOTE Project was associated mainly with sampling activities. Waste management activities may represent a significant contribution to the overall cost of the response/recovery operation. This paper addresses the waste management activities for the BOTE field test. Management of waste is a critical element of activities dealing with remediation of buildings and outdoor areas following a biological contamination incident. Waste management must be integrated into the overall remediation process, along with sampling, decontamination, resource management, and other important response elements, rather than being a stand-alone activity. The results presented in this paper will provide decision makers and emergency planners at the federal/state/tribal/local level information that can be used to integrate waste management into an overall systems approach to planning and response activities.

Training mechanical engineering students to utilize biological inspiration during product development.

PubMed

Bruck, Hugh A; Gershon, Alan L; Golden, Ira; Gupta, Satyandra K; Gyger, Lawrence S; Magrab, Edward B; Spranklin, Brent W

2007-12-01

The use of bio-inspiration for the development of new products and devices requires new educational tools for students consisting of appropriate design and manufacturing technologies, as well as curriculum. At the University of Maryland, new educational tools have been developed that introduce bio-inspired product realization to undergraduate mechanical engineering students. These tools include the development of a bio-inspired design repository, a concurrent fabrication and assembly manufacturing technology, a series of undergraduate curriculum modules and a new senior elective in the bio-inspired robotics area. This paper first presents an overview of the two new design and manufacturing technologies that enable students to realize bio-inspired products, and describes how these technologies are integrated into the undergraduate educational experience. Then, the undergraduate curriculum modules are presented, which provide students with the fundamental design and manufacturing principles needed to support bio-inspired product and device development. Finally, an elective bio-inspired robotics project course is present, which provides undergraduates with the opportunity to demonstrate the application of the knowledge acquired through the curriculum modules in their senior year using the new design and manufacturing technologies.

Toothbrushing abrasion susceptibility of enamel and dentin bleached with calcium-supplemented hydrogen peroxide gel.

PubMed

Borges, A B; Santos, L F T F; Augusto, M G; Bonfiette, D; Hara, A T; Torres, C R G

2016-06-01

The objective of this study was to evaluate enamel and dentin susceptibility to toothbrushing abrasion, after bleaching with 7.5% hydrogen peroxide (HP) gel supplemented or not with 0.5% calcium gluconate (Ca). Toothbrushing was performed immediately and 1h after bleaching, with two suspensions (high and low abrasivity). Bovine enamel and dentin specimens were divided into 12 groups (n=10) according to the bleaching gel (with and without Ca), slurry abrasivity (high or low) and elapsed time after bleaching (immediately and after 1h). As control, a group was not bleached, but abraded. The treatment cycle (7 d) consisted of bleaching (1h) and toothbrushing (135 strokes/day) immediatelly or after 1h of artificial saliva exposure. Surface roughness and surface loss (μm) were measured by profilometry and analysed by three-way ANOVA (5%). Surface roughness means were significantly influenced by slurry abrasivity (p<0.0001). For enamel loss, significant triple interaction was observed (p<0.0001). HP-bleached groups and immediately brushed with high-abrasive slurry exhibited increased loss (1.41±0.14) compared to other groups (μm). Control and HP+Ca-bleached groups brushed after 1h with low abrasive slurry presented the lowest loss (0.21±0.03/0.27±0.02). For dentin loss, significant interaction was observed for bleaching and interval factors (p<0.001). 7.5%HP-bleached groups and immediately brushed showed significantly higher loss (8.71±2.45) than the other groups. It was concluded that surface roughness increased when high abrasive was used, independently of bleaching. 7.5%HP increased enamel and dentin loss, mainly with high abrasive slurries. Calcium supplementation of bleaching gel reduced surface loss. Additionally, in order to minimize tooth wear susceptibility, it is recommended to delay brushing after bleaching. After bleaching gel application, postponing toothbrushing is recommended, as well as brushing with low abrasive dentifrices. Additionally, supplementation of hydrogen peroxide gel with calcium-based remineralizing agent potentially reduces tooth loss after abrasion. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of Bleaching Regimen and Time Elapsed on Microtensile Bond Strength of Resin Composite to Enamel

PubMed Central

Topcu, Fulya Toksoy; Erdemir, Ugur; Ozel, Emre; Tiryaki, Murat; Oktay, Elif Aybala; Yildiz, Esra

2017-01-01

Objectives: The aim of this study was to evaluate the effects of time elapsed since bleaching and different bleaching regimens on the microtensile bond strength of resin composite to enamel. Methodology: Forty flattened buccal enamel surfaces were divided into four groups: An unbleached (control) group and three bleaching groups. Control group specimens were not subjected to a bleaching regimen (Group 1), while those in the bleaching groups were bleached as follows: opalescence 10% (Group 2), whiteness perfect 16% (Group 3), and whiteness hydrogen peroxide 35% (Group 4). Thereafter, the bleached specimens were divided into three subgroups (n = 4 teeth each) for restoration according to predetermined posttreatment time intervals (immediately, 1 week, and 2 weeks). Bonded specimens were then sectioned and subjected to μTBS testing. The data were analyzed using Kruskal–Wallis and Mann–Whitney U-tests at α = 0.05. Results: There was a significant difference in the μTBS of the resin composite to enamel in groups that were bonded immediately after bleaching and in the control group (P < 0.05). Compared to the control group, the μTBS in Groups 2, 3, and 4 decreased significantly 1-week postbleaching (P < 0.05). No significant difference in μTBS was observed between the bleached and unbleached groups 2 weeks after treatment (P > 0.05). Conclusions: Adhesive restorative procedures could not be performed immediately or after 1 week irrespective of the type or concentration of bleaching system used. Composite restorations on bleached enamel surfaces should be performed after an interval of at least 2 weeks. PMID:29042734

Influence of Bleaching Regimen and Time Elapsed on Microtensile Bond Strength of Resin Composite to Enamel.

PubMed

Topcu, Fulya Toksoy; Erdemir, Ugur; Ozel, Emre; Tiryaki, Murat; Oktay, Elif Aybala; Yildiz, Esra

2017-01-01

The aim of this study was to evaluate the effects of time elapsed since bleaching and different bleaching regimens on the microtensile bond strength of resin composite to enamel. Forty flattened buccal enamel surfaces were divided into four groups: An unbleached (control) group and three bleaching groups. Control group specimens were not subjected to a bleaching regimen (Group 1), while those in the bleaching groups were bleached as follows: opalescence 10% (Group 2), whiteness perfect 16% (Group 3), and whiteness hydrogen peroxide 35% (Group 4). Thereafter, the bleached specimens were divided into three subgroups ( n = 4 teeth each) for restoration according to predetermined posttreatment time intervals (immediately, 1 week, and 2 weeks). Bonded specimens were then sectioned and subjected to μTBS testing. The data were analyzed using Kruskal-Wallis and Mann-Whitney U-tests at α = 0.05. There was a significant difference in the μTBS of the resin composite to enamel in groups that were bonded immediately after bleaching and in the control group ( P < 0.05). Compared to the control group, the μTBS in Groups 2, 3, and 4 decreased significantly 1-week postbleaching ( P < 0.05). No significant difference in μTBS was observed between the bleached and unbleached groups 2 weeks after treatment ( P > 0.05). Adhesive restorative procedures could not be performed immediately or after 1 week irrespective of the type or concentration of bleaching system used. Composite restorations on bleached enamel surfaces should be performed after an interval of at least 2 weeks.

YouTube as a source of information on skin bleaching: a content analysis.

PubMed

Basch, C H; Brown, A A; Fullwood, M D; Clark, A; Fung, I C-H; Yin, J

2018-06-01

Skin bleaching is a common, yet potentially harmful body modification practice. To describe the characteristics of the most widely viewed YouTube™ videos related to skin bleaching. The search term 'skin bleaching' was used to identify the 100 most popular English-language YouTube videos relating to the topic. Both descriptive and specific information were noted. Among the 100 manually coded skin-bleaching YouTube videos in English, there were 21 consumer-created videos, 45 internet-based news videos, 30 television news videos and 4 professional videos. Excluding the 4 professional videos, we limited our content categorization and regression analysis to 96 videos. Approximately 93% (89/96) of the most widely viewed videos mentioned changing how you look and 74% (71/96) focused on bleaching the whole body. Of the 96 videos, 63 (66%) of videos showed/mentioned a transformation. Only about 14% (13/96) mentioned that skin bleaching is unsafe. The likelihood of a video selling a skin bleaching product was 17 times higher in internet videos compared with consumer videos (OR = 17.00, 95% CI 4.58-63.09, P < 0.001). Consumer-generated videos were about seven times more likely to mention making bleaching products at home compared with internet-based news videos (OR = 6.86, 95% CI 1.77-26.59, P < 0.01). The most viewed YouTube video on skin bleaching was uploaded by an internet source. Videos made by television sources mentioned more information about skin bleaching being unsafe, while consumer-generated videos focused more on making skin-bleaching products at home. © 2017 British Association of Dermatologists.

The effect of light-activation sources on tooth bleaching

PubMed Central

Baroudi, Kusai; Hassan, Nadia Aly

2014-01-01

Vital bleaching is one of the most requested cosmetic dental procedures asked by patients who seek a more pleasing smile. This procedure consists of carbamide or hydrogen peroxide gel applications that can be applied in-office or by the patient (at-home/overnight bleaching system). Some in-office treatments utilise whitening light with the objective of speeding up the whitening process. The objective of this article is to review and summarise the current literature with regard to the effect of light-activation sources on in-office tooth bleaching. A literature search was conducted using Medline, accessed via the National Library of Medicine Pub Med from 2003 to 2013 searching for articles relating to effectiveness of light activation sources on in-office tooth bleaching. This study found conflicting evidence on whether light truly improve tooth whitening. Other factors such as, type of stain, initial tooth colour and subject age which can influence tooth bleaching outcome were discussed. Conclusions: The use of light activator sources with in-office bleaching treatment of vital teeth did not increase the efficacy of bleaching or accelerate the bleaching. PMID:25298598

Bleaching of cotton fabric with tetraacetylhydrazine as bleach activator for H2O2.

PubMed

Liu, Kai; Zhang, Xuan; Yan, Kelu

2018-05-15

Tetraacetylhydrazine (TH) as bleach activator for H 2 O 2 cotton bleaching was synthesized and characterized by 1 H NMR, 13 C NMR and MS spectra. TH has better solubility than that of TAED. The CIE whiteness index (WI), H 2 O 2 decomposition rate and bursting strength were employed to investigate the performance of H 2 O 2 /TH bleaching system. By addition of TH, WI and H 2 O 2 decomposition rate increased significantly at 70 °C. Bleaching temperature, NaHCO 3 concentration and bleaching time were also discussed in detail and the loss of bursting strength is not clear. By using benzenepentacarboxylic acid (BA) as a fluorescent probe for hydroxyl radical detection, the bleaching process of H 2 O 2 /TH system was investigated. Acetylhydrazine and diacetylhydrazine were also utilized to further confirm the process. In addition, bimolecular decomposition was investigated by using 9,10-dimethylanthracene (DMA) as fluorescent probe of 1 O 2 . Based on these experimental results, the bleaching mechanism of H 2 O 2 /TH system was proposed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of a New Bleaching Gel on Tooth Whitening.

PubMed

Barry, T N; Bailey, C W; Ashcraft-Olmscheid, D; Vandewalle, K S

The purpose of this study was to compare the whitening efficacy of a novel bleaching agent containing a unique tribarrel hydremide-peroxide gel (KöR) with a traditional bleaching system of hydrogen peroxide or carbamide peroxide (Opalescence). Bovine incisors were mounted into a custom resin, arch-shaped mounting device. Four groups of 10 teeth were created using mounting devices containing five teeth each. The in-office and home bleaching gels of KöR and Opalescence were applied to the teeth alone and in trays to simulate a combination of in-office and home bleaching or home bleaching only. Spectrophotometer readings of L* a* b* were performed at baseline, the end of active bleaching (immediate), and three and six months postbleaching. Immediately postbleaching, the use of Opalescence gel resulted in greater change in ΔE* and Δb* (less yellow) for combined and home bleaching techniques compared with KöR. After six months, Opalescence had significantly greater ΔE* and Δb* compared with KöR for home bleaching only. There was no significant difference in ΔL* between Opalescence and KöR at any time period with either technique.

Evaluation of bleach-sedimentation for sterilising and concentrating Mycobacterium tuberculosis in sputum specimens

PubMed Central

2011-01-01

Background Bleach-sedimentation may improve microscopy for diagnosing tuberculosis by sterilising sputum and concentrating Mycobacterium tuberculosis. We studied gravity bleach-sedimentation effects on safety, sensitivity, speed and reliability of smear-microscopy. Methods This blinded, controlled study used sputum specimens (n = 72) from tuberculosis patients. Bleach concentrations and exposure times required to sterilise sputum (n = 31) were determined. In the light of these results, the performance of 5 gravity bleach-sedimentation techniques that sterilise sputum specimens (n = 16) were compared. The best-performing of these bleach-sedimentation techniques involved adding 1 volume of 5% bleach to 1 volume of sputum, shaking for 10-minutes, diluting in 8 volumes distilled water and sedimenting overnight before microscopy. This technique was further evaluated by comparing numbers of visible acid-fast bacilli, slide-reading speed and reliability for triplicate smears before versus after bleach-sedimentation of sputum specimens (n = 25). Triplicate smears were made to increase precision and were stained using the Ziehl-Neelsen method. Results M. tuberculosis in sputum was successfully sterilised by adding equal volumes of 15% bleach for 1-minute, 6% for 5-minutes or 3% for 20-minutes. Bleach-sedimentation significantly decreased the number of acid-fast bacilli visualised compared with conventional smears (geometric mean of acid-fast bacilli per 100 microscopy fields 166, 95%CI 68-406, versus 346, 95%CI 139-862, respectively; p = 0.02). Bleach-sedimentation diluted paucibacillary specimens less than specimens with higher concentrations of visible acid-fast bacilli (p = 0.02). Smears made from bleach-sedimented sputum were read more rapidly than conventional smears (9.6 versus 11.2 minutes, respectively, p = 0.03). Counting conventional acid-fast bacilli had high reliability (inter-observer agreement, r = 0.991) that was significantly reduced (p = 0.03) by bleach-sedimentation (to r = 0.707) because occasional strongly positive bleach-sedimented smears were misread as negative. Conclusions Gravity bleach-sedimentation improved laboratory safety by sterilising sputum but decreased the concentration of acid-fast bacilli visible on microscopy, especially for sputum specimens containing high concentrations of M. tuberculosis. Bleach-sedimentation allowed examination of more of each specimen in the time available but decreased the inter-observer reliability with which slides were read. Thus bleach-sedimentation effects vary depending upon specimen characteristics and whether microscopy was done for a specified time, or until a specified number of microscopy fields had been read. These findings provide an explanation for the contradictory results of previous studies. PMID:21985457

Ultrasound promoted reaction of Rhodamine B with sodium hypochlorite using sonochemical and dental ultrasonic instruments.

PubMed

Tiong, T Joyce; Price, Gareth J

2012-03-01

The sonochemical acceleration of bleaching of Rhodamine B by sodium hypochlorite has been studied using ultrasound intensities in the range 0-7 W cm(-2). Using a 20 kHz ultrasonic horn, it was shown that ultrasound could significantly shorten the treatment time and/or the concentration of hypochlorite required for the reaction. A number of intermediate species formed during the reaction have been identified. It was demonstrated that the same sonochemical reactions occur during the use of dental ultrasound instruments of the type used in endodontics where hypochlorite solutions act as disinfectants. Results showed pseudo-first order degradation kinetics for the degradation of Rhodamine B for both types of source. Both the distribution of cavitation and the resulting bleaching reactions were dependent on the design of the tips. The bleaching reaction can therefore be used to characterise the behaviour of dental instruments and aid in the optimisation of their performance. Copyright © 2011 Elsevier B.V. All rights reserved.

The effects of physical refining on the formation of 3-monochloropropane-1,2-diol esters in relation to palm oil minor components.

PubMed

Zulkurnain, Musfirah; Lai, Oi Ming; Latip, Razam Abdul; Nehdi, Imededdine Arbi; Ling, Tau Chuan; Tan, Chin Ping

2012-11-15

The formation of 3-monochloropropane-1,2-diol (3-MCPD) esters in refined palm oil during deodorisation is attributed to the intrinsic composition of crude palm oil. Utilising D-optimal design, the effects of the degumming and bleaching processes on the reduction in 3-MCPD ester formation in refined palm oil from poor-quality crude palm oil were studied relative to the palm oil minor components that are likely to be their precursors. Water degumming remarkably reduced 3-MCPD ester formation by up to 84%, from 9.79 mg/kg to 1.55 mg/kg. Bleaching with synthetic magnesium silicate caused a further 10% reduction, to 0.487 mg/kg. The reduction in 3-MCPD ester formation could be due to the removal of related precursors prior to the deodorisation step. The phosphorus content of bleached palm oil showed a significant correlation with 3-MCPD ester formation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Coral bleaching at Little Cayman, Cayman Islands 2009

NASA Astrophysics Data System (ADS)

van Hooidonk, Ruben J.; Manzello, Derek P.; Moye, Jessica; Brandt, Marilyn E.; Hendee, James C.; McCoy, Croy; Manfrino, Carrie

2012-06-01

The global rise in sea temperature through anthropogenic climate change is affecting coral reef ecosystems through a phenomenon known as coral bleaching; that is, the whitening of corals due to the loss of the symbiotic zooxanthellae which impart corals with their characteristic vivid coloration. We describe aspects of the most prevalent episode of coral bleaching ever recorded at Little Cayman, Cayman Islands, during the fall of 2009. The most susceptible corals were found to be, in order, Siderastrea siderea, Montastraea annularis, and Montastraea faveolata, while Diplora strigosa and Agaricia spp. were less so, yet still showed considerable bleaching prevalence and severity. Those found to be least susceptible were Porites porites, Porites astreoides, and Montastraea cavernosa. These observations and other reported observations of coral bleaching, together with 29 years (1982-2010) of satellite-derived sea surface temperatures, were used to optimize bleaching predictions at this location. To do this a Degree Heating Weeks (DHW) and Peirce Skill Score (PSS) analysis was employed to calculate a local bleaching threshold above which bleaching was expected to occur. A threshold of 4.2 DHW had the highest skill, with a PSS of 0.70. The method outlined here could be applied to other regions to find the optimal bleaching threshold and improve bleaching predictions.

The 2014 coral bleaching and freshwater flood events in Kāne'ohe Bay, Hawai'i.

PubMed

Bahr, Keisha D; Jokiel, Paul L; Rodgers, Kuʻulei S

2015-01-01

Until recently, subtropical Hawai'i escaped the major bleaching events that have devastated many tropical regions, but the continued increases in global long-term mean temperatures and the apparent ending of the Pacific Decadal Oscillation (PDO) cool phase have increased the risk of bleaching events. Climate models and observations predict that bleaching in Hawai'i will occur with increasing frequency and increasing severity over future decades. A freshwater "kill" event occurred during July 2014 in the northern part of Kāne'ohe Bay that reduced coral cover by 22.5% in the area directly impacted by flooding. A subsequent major bleaching event during September 2014 caused extensive coral bleaching and mortality throughout the bay and further reduced coral cover in the freshwater kill area by 60.0%. The high temperature bleaching event only caused a 1.0% reduction in live coral throughout the portion of the bay not directly impacted by the freshwater event. Thus, the combined impact of the low salinity event and the thermal bleaching event appears to be more than simply additive. The temperature regime during the September 2014 bleaching event was analogous in duration and intensity to that of the large bleaching event that occurred previously during August 1996, but resulted in a much larger area of bleaching and coral mortality. Apparently seasonal timing as well as duration and magnitude of heating is important. Coral spawning in the dominant coral species occurs early in the summer, so reservoirs of stored lipid in the corals had been depleted by spawning prior to the September 2014 event. Warm months above 27 °C result in lower coral growth and presumably could further decrease lipid reserves, leading to a bleaching event that was more severe than would have happened if the high temperatures occurred earlier in the summer. Hawaiian reef corals decrease skeletal growth at temperatures above 27 °C, so perhaps the "stress period" actually started long before the bleaching threshold of 29 °C was reached. Hawai'i is directly influenced by the PDO which may become a factor influencing bleaching events in subtropical Hawai'i in much the same manner as variations in the El Niño Southern Oscillation (ENSO) influences bleaching events at low latitudes in the tropical Pacific. Records show that offshore temperatures measured by satellite will not always predict inshore bleaching because other factors (high cloud cover, high wind and wave action, tidal exchange rate) can limit inshore heating and prevent temperatures in the bay from reaching the bleaching threshold. Low light levels due to cloud cover or high turbidity can also serve to prevent bleaching.

The 2014 coral bleaching and freshwater flood events in Kāneʻohe Bay, Hawaiʻi

PubMed Central

Jokiel, Paul L.; Rodgers, Kuʻulei S.

2015-01-01

Until recently, subtropical Hawaiʻi escaped the major bleaching events that have devastated many tropical regions, but the continued increases in global long-term mean temperatures and the apparent ending of the Pacific Decadal Oscillation (PDO) cool phase have increased the risk of bleaching events. Climate models and observations predict that bleaching in Hawaiʻi will occur with increasing frequency and increasing severity over future decades. A freshwater “kill” event occurred during July 2014 in the northern part of Kāneʻohe Bay that reduced coral cover by 22.5% in the area directly impacted by flooding. A subsequent major bleaching event during September 2014 caused extensive coral bleaching and mortality throughout the bay and further reduced coral cover in the freshwater kill area by 60.0%. The high temperature bleaching event only caused a 1.0% reduction in live coral throughout the portion of the bay not directly impacted by the freshwater event. Thus, the combined impact of the low salinity event and the thermal bleaching event appears to be more than simply additive. The temperature regime during the September 2014 bleaching event was analogous in duration and intensity to that of the large bleaching event that occurred previously during August 1996, but resulted in a much larger area of bleaching and coral mortality. Apparently seasonal timing as well as duration and magnitude of heating is important. Coral spawning in the dominant coral species occurs early in the summer, so reservoirs of stored lipid in the corals had been depleted by spawning prior to the September 2014 event. Warm months above 27 °C result in lower coral growth and presumably could further decrease lipid reserves, leading to a bleaching event that was more severe than would have happened if the high temperatures occurred earlier in the summer. Hawaiian reef corals decrease skeletal growth at temperatures above 27 °C, so perhaps the “stress period” actually started long before the bleaching threshold of 29 °C was reached. Hawaiʻi is directly influenced by the PDO which may become a factor influencing bleaching events in subtropical Hawaiʻi in much the same manner as variations in the El Niño Southern Oscillation (ENSO) influences bleaching events at low latitudes in the tropical Pacific. Records show that offshore temperatures measured by satellite will not always predict inshore bleaching because other factors (high cloud cover, high wind and wave action, tidal exchange rate) can limit inshore heating and prevent temperatures in the bay from reaching the bleaching threshold. Low light levels due to cloud cover or high turbidity can also serve to prevent bleaching. PMID:26290792

Climate, bleaching and connectivity in the Coral Triangle.

NASA Astrophysics Data System (ADS)

Curchitser, E. N.; Kleypas, J. A.; Castruccio, F. S.; Drenkard, E.; Thompson, D. M.; Pinsky, M. L.

2016-12-01

The Coral Triangle (CT) is the apex of marine biodiversity and supports the livelihoods of millions of people. It is also one of the most threatened of all reef regions in the world. We present results from a series of high-resolution, numerical ocean models designed to address physical and ecological questions relevant to the region's coral communities. The hierarchy of models was designed to optimize the model performance in addressing questions ranging from the role of internal tides in larval connectivity to distinguishing the role of interannual variability from decadal trends in thermal stress leading to mass bleaching events. In this presentation we will show how combining ocean circulation with models of larval dispersal leads to new insights into the interplay of physics and ecology in this complex oceanographic region, which can ultimately be used to inform conservation efforts.

High-resolution modeling of thermal thresholds and environmental influences on coral bleaching for local and regional reef management.

PubMed

Kumagai, Naoki H; Yamano, Hiroya

2018-01-01

Coral reefs are one of the world's most threatened ecosystems, with global and local stressors contributing to their decline. Excessive sea-surface temperatures (SSTs) can cause coral bleaching, resulting in coral death and decreases in coral cover. A SST threshold of 1 °C over the climatological maximum is widely used to predict coral bleaching. In this study, we refined thermal indices predicting coral bleaching at high-spatial resolution (1 km) by statistically optimizing thermal thresholds, as well as considering other environmental influences on bleaching such as ultraviolet (UV) radiation, water turbidity, and cooling effects. We used a coral bleaching dataset derived from the web-based monitoring system Sango Map Project, at scales appropriate for the local and regional conservation of Japanese coral reefs. We recorded coral bleaching events in the years 2004-2016 in Japan. We revealed the influence of multiple factors on the ability to predict coral bleaching, including selection of thermal indices, statistical optimization of thermal thresholds, quantification of multiple environmental influences, and use of multiple modeling methods (generalized linear models and random forests). After optimization, differences in predictive ability among thermal indices were negligible. Thermal index, UV radiation, water turbidity, and cooling effects were important predictors of the occurrence of coral bleaching. Predictions based on the best model revealed that coral reefs in Japan have experienced recent and widespread bleaching. A practical method to reduce bleaching frequency by screening UV radiation was also demonstrated in this paper.

Can a bleaching toothpaste containing Blue Covarine demonstrate the same bleaching as conventional techniques? An in vitro, randomized and blinded study.

PubMed

Dantas, Andréa Abi Rached; Bortolatto, Janaina Freitas; Roncolato, Ávery; Merchan, Hugo; Floros, Michael Christopher; Kuga, Milton Carlos; Oliveira Junior, Osmir Batista de

2015-01-01

The purpose of this in vitro study was to compare the efficacy of a bleaching toothpaste containing Blue Covarine vs. conventional tooth bleaching techniques using peroxides (both in-office and at-home). Samples were randomly distributed into five experimental groups (n=15): C - Control; BC - Bleaching toothpaste containing Blue Covarine; WBC - Bleaching toothpaste without Blue Covarine; HP35 - In-office bleaching using 35% hydrogen peroxide; and CP10 - At-home bleaching with 10% carbamide peroxide. The dental bleaching efficacy was determined by the color difference (ΔE), luminosity (ΔL), green-red axis (Δa), and blue-yellow axis (Δb). The CIELab coordinates were recorded with reflectance spectroscopy at different times: T0 - baseline, T1 - immediately after bleaching, T2 - 7 days, T3 - 14 days, and T4 - 21 days after the end of treatments. Data were analyzed by a repeated measures mixed ANOVA and post hoc Bonferroni test, with a significance level of 5%. No significant differences were found between the treatment groups C, BC, and WBC. The groups HP35 and CP10 showed significantly higher whitening efficacy than groups C, BC, and WBC. There were no significant differences in the whitening efficacy between a Blue Covarine containing toothpaste, a standard whitening toothpaste, and a control. Neither of the whitening toothpastes tested were as effective as in-office or at-home bleaching treatments.

Can a bleaching toothpaste containing Blue Covarine demonstrate the same bleaching as conventional techniques? An in vitro, randomized and blinded study

PubMed Central

DANTAS, Andréa Abi Rached; BORTOLATTO, Janaina Freitas; RONCOLATO, Ávery; MERCHAN, Hugo; FLOROS, Michael Christopher; KUGA, Milton Carlos; de OLIVEIRA, Osmir Batista

2015-01-01

ABSTRACT Objective The purpose of this in vitro study was to compare the efficacy of a bleaching toothpaste containing Blue Covarine vs. conventional tooth bleaching techniques using peroxides (both in-office and at-home). Material and Methods Samples were randomly distributed into five experimental groups (n=15): C - Control; BC – Bleaching toothpaste containing Blue Covarine; WBC – Bleaching toothpaste without Blue Covarine; HP35 - In-office bleaching using 35% hydrogen peroxide; and CP10 – At-home bleaching with 10% carbamide peroxide. The dental bleaching efficacy was determined by the color difference (ΔE), luminosity (ΔL), green-red axis (Δa), and blue-yellow axis (Δb). The CIELab coordinates were recorded with reflectance spectroscopy at different times: T0 - baseline, T1 – immediately after bleaching, T2 - 7 days, T3 - 14 days, and T4 - 21 days after the end of treatments. Data were analyzed by a repeated measures mixed ANOVA and post hoc Bonferroni test, with a significance level of 5%. Results No significant differences were found between the treatment groups C, BC, and WBC. The groups HP35 and CP10 showed significantly higher whitening efficacy than groups C, BC, and WBC. Conclusions There were no significant differences in the whitening efficacy between a Blue Covarine containing toothpaste, a standard whitening toothpaste, and a control. Neither of the whitening toothpastes tested were as effective as in-office or at-home bleaching treatments. PMID:26814462

Unexpected promotion of PCDD/F formation by enzyme-aided Cl2 bleaching in non-wood pulp and paper mill.

PubMed

Fang, Liping; Zheng, Minghui; Liu, Guorui; Zhao, Yuyang; Liu, Wenbin; Huang, Linyan; Guo, Li

2017-02-01

Enzyme-aided Cl 2 bleaching is widely considered as promising replacements for conventional Cl 2 bleaching in wood pulp and paper mills. However, the effects of using enzyme-aided bleaching on the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the non-wood pulp and paper mills are unclear. A field study was performed to investigate PCDD/F formation when enzyme-aided Cl 2 bleaching was used to replace conventional Cl 2 bleaching in non-wood pulp and paper mills. Unexpectedly, the PCDD/F toxic equivalents (TEQs) in solid samples were higher when using enzyme-aided bleaching (0.49-5.4 pg TEQ/g) than that using conventional Cl 2 bleaching (0.15-2.44 pg TEQ/g). Large amounts of octachlorodibenzo-p-dioxin were formed during the enzyme-aided bleaching process. This could have been because enzyme strongly promoted the release of organic molecules bound to lignin and thus accelerated the formation of octachlorodibenzo-p-dioxin through organic molecular precursors. Although enzyme-aided Cl 2 bleaching was previously considered to be efficient for reducing PCDD/F releases and to be the best available technologies and best environmental practices for wood pulp and paper mills, the results obtained in this study suggested the necessity and urgency to evaluate the suitability of enzyme-aided Cl 2 bleaching for non-wood pulp and paper mills that intensively practiced in developing countries. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of coffee and a cola-based soft drink on the color stability of bleached bovine incisors considering the time elapsed after bleaching.

PubMed

Pirolo, Rodrigo; Mondelli, Rafael Francisco Lia; Correr, Gisele Maria; Gonzaga, Carla Castiglia; Furuse, Adilson Yoshio

2014-01-01

There is no consensus about the waiting time necessary for the patient to start consuming beverages containing colorants again after bleaching. To evaluate the influence of beverages with coloring agents on bleached bovine incisors considering the time elapsed after bleaching. Sixty bovine incisors were bleached with 35% hydrogen peroxide for in-office use (Whiteness HP Max) and divided into 10 groups. The color was evaluated with a spectrophotometer (Spectro Shade MICRO) before and after bleaching, employing the CIE-Lab system. After bleaching, the teeth were exposed for 5 min to coffee or cola-based soft drink (CBSD) at different periods after bleaching: 10 min, 1 h, 24 h, 48 h, and 72 h. Color (∆E) and lightness (∆L) variations were obtained from the CIE-Lab coordinates. Data were subjected to two-way ANOVA and Tukey HSD tests (p<0.05). Significant differences were observed between groups for both the ∆L and ∆E values (p<0.001). All specimens presented a decrease in brightness (negative ∆L). The highest ∆E values were observed for teeth stained with a CBSD at 10 min and 1 h (4.12 and 4.16, respectively). Teeth pigmented with coffee presented ∆E values below 3.3 units for all evaluation times. The exposure to coffee after bleaching causes less color changes than the exposure to a CBSD regardless of the time after bleaching.

Microtensile bond strength of enamel after bleaching.

PubMed

Lago, Andrea Dias Neves; Garone-Netto, Narciso

2013-01-01

To evaluate the bond strength of a composite resin to the bovine enamel bleached with 35% hydrogen peroxide. It was used an etching-and-rinse adhesive system employed immediately, 7 and 14 days after the bleaching. Twenty bovine teeth were randomly distributed into 4 groups (n = 5), 3 experimental and 1 control. G1: Unbleached + restoration 14 days after storage in artificial saliva (control); G2: Bleached + restoration immediately after bleaching; G3: Bleached + restoration 7 days after bleaching; G4: Bleached + restoration 14 days after bleaching. Their buccal enamel surfaces were flattened, and a 25 mm² (5 × 5 mm) area from each one of these regions was outlined so as to standardize the experimental region. Universal hybrid composite resin Filtek™Z350 was inserted into four layers of 1 mm each and photo-activated. The bond strength was quantitatively evaluated by a microtensile test (1.0 mm/min) 24 h after the restorative procedures. The failure mode was assessed through scanning electron microscopy (SEM). There was a significant reduction in the bond strength of the restored teeth immediately after the bleaching (G2). There were no significant differences in enamel bond strength between groups G1, G3, and G4. There was a predominance of adhesive and mixed (cohesive + adhesive) failure in all groups. The 7-day-period after the end of the bleaching with 35% hydrogen peroxide was enough to achieve the appropriate values of bond strength to the enamel.

Optimizing acidified bleach solutions to improve sporicidal efficacy on building materials.

PubMed

Wood, J P; Calfee, M W; Clayton, M; Griffin-Gatchalian, N; Touati, A

2011-12-01

We evaluated whether lowering pH (with acetic acid) and raising free available chlorine (FAC) levels in bleach solutions would improve efficacy in inactivating Bacillus spores on different materials. We also determined how varying pH and FAC levels affected bleach stability. Acidified bleach solutions with pH levels of 4.5, 6 and 7.5 and FAC levels between 5000 and 10,000 ppm were evaluated for decontamination efficacy against Bacillus subtilis spores inoculated onto test coupons made from wood, ceramic and galvanized steel. Lowering the pH or increasing the FAC level improved efficacy in some of the tests, but depended on the material, which significantly affected decontamination efficacy. The acidified bleach at pH of 7.5 was significantly less effective than bleach at a pH of 4.5 or 6. The FAC levels in the bleach were the most stable at pH 4.5, and stability at pH 4.5 was not significantly affected by the initial FAC level. It may be advisable to use bleach solutions with lower pH (rather than high FAC levels) in light of both the decontamination efficacy and bleach stability results. For wood materials, use of sporicides other than acidified bleach may be warranted. These results may be useful in preparing acidified bleach solutions for decontamination of materials contaminated with spores such as Bacillus anthracis. © 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

High-resolution modeling of thermal thresholds and environmental influences on coral bleaching for local and regional reef management

PubMed Central

Yamano, Hiroya

2018-01-01

Coral reefs are one of the world’s most threatened ecosystems, with global and local stressors contributing to their decline. Excessive sea-surface temperatures (SSTs) can cause coral bleaching, resulting in coral death and decreases in coral cover. A SST threshold of 1 °C over the climatological maximum is widely used to predict coral bleaching. In this study, we refined thermal indices predicting coral bleaching at high-spatial resolution (1 km) by statistically optimizing thermal thresholds, as well as considering other environmental influences on bleaching such as ultraviolet (UV) radiation, water turbidity, and cooling effects. We used a coral bleaching dataset derived from the web-based monitoring system Sango Map Project, at scales appropriate for the local and regional conservation of Japanese coral reefs. We recorded coral bleaching events in the years 2004–2016 in Japan. We revealed the influence of multiple factors on the ability to predict coral bleaching, including selection of thermal indices, statistical optimization of thermal thresholds, quantification of multiple environmental influences, and use of multiple modeling methods (generalized linear models and random forests). After optimization, differences in predictive ability among thermal indices were negligible. Thermal index, UV radiation, water turbidity, and cooling effects were important predictors of the occurrence of coral bleaching. Predictions based on the best model revealed that coral reefs in Japan have experienced recent and widespread bleaching. A practical method to reduce bleaching frequency by screening UV radiation was also demonstrated in this paper. PMID:29473007

Contrasting patterns of coral bleaching susceptibility in 2010 suggest an adaptive response to thermal stress.

PubMed

Guest, James R; Baird, Andrew H; Maynard, Jeffrey A; Muttaqin, Efin; Edwards, Alasdair J; Campbell, Stuart J; Yewdall, Katie; Affendi, Yang Amri; Chou, Loke Ming

2012-01-01

Coral bleaching events vary in severity, however, to date, the hierarchy of susceptibility to bleaching among coral taxa has been consistent over a broad geographic range and among bleaching episodes. Here we examine the extent of spatial and temporal variation in thermal tolerance among scleractinian coral taxa and between locations during the 2010 thermally induced, large-scale bleaching event in South East Asia. Surveys to estimate the bleaching and mortality indices of coral genera were carried out at three locations with contrasting thermal and bleaching histories. Despite the magnitude of thermal stress being similar among locations in 2010, there was a remarkable contrast in the patterns of bleaching susceptibility. Comparisons of bleaching susceptibility within coral taxa and among locations revealed no significant differences between locations with similar thermal histories, but significant differences between locations with contrasting thermal histories (Friedman = 34.97; p<0.001). Bleaching was much less severe at locations that bleached during 1998, that had greater historical temperature variability and lower rates of warming. Remarkably, Acropora and Pocillopora, taxa that are typically highly susceptible, although among the most susceptible in Pulau Weh (Sumatra, Indonesia) where respectively, 94% and 87% of colonies died, were among the least susceptible in Singapore, where only 5% and 12% of colonies died. The pattern of susceptibility among coral genera documented here is unprecedented. A parsimonious explanation for these results is that coral populations that bleached during the last major warming event in 1998 have adapted and/or acclimatised to thermal stress. These data also lend support to the hypothesis that corals in regions subject to more variable temperature regimes are more resistant to thermal stress than those in less variable environments.

A new, high-resolution global mass coral bleaching database

PubMed Central

Rickbeil, Gregory J. M.; Heron, Scott F.

2017-01-01

Episodes of mass coral bleaching have been reported in recent decades and have raised concerns about the future of coral reefs on a warming planet. Despite the efforts to enhance and coordinate coral reef monitoring within and across countries, our knowledge of the geographic extent of mass coral bleaching over the past few decades is incomplete. Existing databases, like ReefBase, are limited by the voluntary nature of contributions, geographical biases in data collection, and the variations in the spatial scale of bleaching reports. In this study, we have developed the first-ever gridded, global-scale historical coral bleaching database. First, we conducted a targeted search for bleaching reports not included in ReefBase by personally contacting scientists and divers conducting monitoring in under-reported locations and by extracting data from the literature. This search increased the number of observed bleaching reports by 79%, from 4146 to 7429. Second, we employed spatial interpolation techniques to develop annual 0.04° × 0.04° latitude-longitude global maps of the probability that bleaching occurred for 1985 through 2010. Initial results indicate that the area of coral reefs with a more likely than not (>50%) or likely (>66%) probability of bleaching was eight times higher in the second half of the assessed time period, after the 1997/1998 El Niño. The results also indicate that annual maximum Degree Heating Weeks, a measure of thermal stress, for coral reefs with a high probability of bleaching increased over time. The database will help the scientific community more accurately assess the change in the frequency of mass coral bleaching events, validate methods of predicting mass coral bleaching, and test whether coral reefs are adjusting to rising ocean temperatures. PMID:28445534

Effects of coral bleaching on the obligate coral-dwelling crab Trapezia cymodoce

NASA Astrophysics Data System (ADS)

Stella, J. S.; Munday, P. L.; Jones, G. P.

2011-09-01

Corals are an essential and threatened habitat for a diverse range of reef-associated animals. Episodes of coral bleaching are predicted to increase in frequency and intensity over coming decades, yet the effects of coral-host bleaching on the associated animal communities remain poorly understood. The present study investigated the effects of host-colony bleaching on the obligate coral-dwelling crab, Trapezia cymodoce, during a natural bleaching event in the lagoon of Lizard Island, Australia. Branching corals, which harbour the highest diversity of coral associates, comprised 13% of live coral cover at the study site, with 83% affected by bleaching. Crabs on healthy and bleached colonies of Pocillopora damicornis were monitored over a 5-week period to determine whether coral bleaching affected crab density and movement patterns. All coral colonies initially contained one breeding pair of crabs. There was a significant decline in crab density on bleached corals after 5 weeks, with many corals losing one or both crabs, yet all healthy colonies retained a mating pair. Fecundity of crabs collected from bleached and healthy colonies of P. damicornis was also compared. The size of egg clutches of crabs collected from bleached hosts was 40% smaller than those from healthy hosts, indicating a significant reduction in fecundity. A laboratory experiment on movement patterns found that host-colony bleaching also prompted crabs to emigrate in search of more suitable colonies. Emigrant crabs engaged in aggressive interactions with occupants of healthy hosts, with larger crabs always usurping occupants of a smaller size. Decreased densities and clutch sizes, along with increased competitive interactions, could potentially result in a population decline of these important coral associates with cascading effects on coral health.

Color recovery effect of different bleaching systems on a discolored composite resin.

PubMed

Gul, P; Harorlı, O T; Ocal, I B; Ergin, Z; Barutcigil, C

2017-10-01

Discoloration of resin-based composites is a commonly encountered problem, and bleaching agents may be used for the therapy of the existing discoloration. The purpose of this study was to investigate in vitro color recovery effect of different bleaching systems on the heavily discolored composite resin. Fifty disk-shaped dental composite specimens were prepared using A2 shade nanohybrid universal composite resin (3M ESPE Filtek Z550, St. Paul, MN, USA). Composite samples were immersed in coffee and turnip juice for 1 week in each. One laser activated bleaching (LB) (Biolase Laserwhite*20) and three conventional bleaching systems (Ultradent Opalescence Boost 40% (OB), Ultradent Opalescence PF 15% home bleaching (HB), Crest 3D White [Whitening Mouthwash]) were tested in this study. Distilled water was used as control group. The color of the samples were measured using a spectrophotometer (VITA Easy shade Compact, VITA Zahnfabrik, Bad Säckingen, Germany). Color changes (ΔE00) were calculated using the CIEDE2000 formula. Statistical analyses were conducted using paired samples test, one-way analysis of variance, and Tukey's multiple comparison tests (α = 0.05). The staining beverages caused perceptible discoloration (ΔE00 > 2.25). The color recovery effect of all bleaching systems was statistically determined to be more effective than the control group (P < 0.05). Although OB group was found as the most effective bleaching system, there was no statistically significant difference among HB, OB, and LB groups (P > 0.05). Within the limitation of this in vitro study, the highest recovery effect was determined in office bleaching system among all bleaching systems. However, home and laser bleaching systems were determined as effective as office bleaching system.

A new, high-resolution global mass coral bleaching database.

PubMed

Donner, Simon D; Rickbeil, Gregory J M; Heron, Scott F

2017-01-01

Episodes of mass coral bleaching have been reported in recent decades and have raised concerns about the future of coral reefs on a warming planet. Despite the efforts to enhance and coordinate coral reef monitoring within and across countries, our knowledge of the geographic extent of mass coral bleaching over the past few decades is incomplete. Existing databases, like ReefBase, are limited by the voluntary nature of contributions, geographical biases in data collection, and the variations in the spatial scale of bleaching reports. In this study, we have developed the first-ever gridded, global-scale historical coral bleaching database. First, we conducted a targeted search for bleaching reports not included in ReefBase by personally contacting scientists and divers conducting monitoring in under-reported locations and by extracting data from the literature. This search increased the number of observed bleaching reports by 79%, from 4146 to 7429. Second, we employed spatial interpolation techniques to develop annual 0.04° × 0.04° latitude-longitude global maps of the probability that bleaching occurred for 1985 through 2010. Initial results indicate that the area of coral reefs with a more likely than not (>50%) or likely (>66%) probability of bleaching was eight times higher in the second half of the assessed time period, after the 1997/1998 El Niño. The results also indicate that annual maximum Degree Heating Weeks, a measure of thermal stress, for coral reefs with a high probability of bleaching increased over time. The database will help the scientific community more accurately assess the change in the frequency of mass coral bleaching events, validate methods of predicting mass coral bleaching, and test whether coral reefs are adjusting to rising ocean temperatures.

Contrasting Patterns of Coral Bleaching Susceptibility in 2010 Suggest an Adaptive Response to Thermal Stress

PubMed Central

Guest, James R.; Baird, Andrew H.; Maynard, Jeffrey A.; Muttaqin, Efin; Edwards, Alasdair J.; Campbell, Stuart J.; Yewdall, Katie; Affendi, Yang Amri; Chou, Loke Ming

2012-01-01

Background Coral bleaching events vary in severity, however, to date, the hierarchy of susceptibility to bleaching among coral taxa has been consistent over a broad geographic range and among bleaching episodes. Here we examine the extent of spatial and temporal variation in thermal tolerance among scleractinian coral taxa and between locations during the 2010 thermally induced, large-scale bleaching event in South East Asia. Methodology/Principal Findings Surveys to estimate the bleaching and mortality indices of coral genera were carried out at three locations with contrasting thermal and bleaching histories. Despite the magnitude of thermal stress being similar among locations in 2010, there was a remarkable contrast in the patterns of bleaching susceptibility. Comparisons of bleaching susceptibility within coral taxa and among locations revealed no significant differences between locations with similar thermal histories, but significant differences between locations with contrasting thermal histories (Friedman = 34.97; p<0.001). Bleaching was much less severe at locations that bleached during 1998, that had greater historical temperature variability and lower rates of warming. Remarkably, Acropora and Pocillopora, taxa that are typically highly susceptible, although among the most susceptible in Pulau Weh (Sumatra, Indonesia) where respectively, 94% and 87% of colonies died, were among the least susceptible in Singapore, where only 5% and 12% of colonies died. Conclusions/Significance The pattern of susceptibility among coral genera documented here is unprecedented. A parsimonious explanation for these results is that coral populations that bleached during the last major warming event in 1998 have adapted and/or acclimatised to thermal stress. These data also lend support to the hypothesis that corals in regions subject to more variable temperature regimes are more resistant to thermal stress than those in less variable environments. PMID:22428027

Is personality relevant in the choice of bleaching?

PubMed

Herrera, A; Martín, J; Pérez, F; Bonafé, E; Reis, A; Dourado, A Loguercio; Fernández, E

2016-11-01

The purpose was to administer the NEO-FFI personality test to patients who did and did not want to have their teeth bleached and before and after bleaching to the participants who accepted the treatment. The research question is to correlate styles and personality factors with bleaching. There were 128 patients eligible for bleaching; 58 accepted (AB) while 70 refused (RB). The test was administered to both groups (AB-RB). The group AB was administered before and 1 week after the end of the bleaching. For each personality domain comparison, the Mann-Whitney test was used. For the group AB, the results for each domain before and after bleaching were compared using the Wilcoxon test. There was a significant difference between the groups (AB-RB) in the extraversion factor (p = 0.01). There was no significant difference between any of the personality items before and after bleaching (p > 0.1). The comparison between groups by sex revealed significant differences in extraversion and neuroticism factors. Males who AB scored higher in extraversion than males who RB (p < 0.05). Females scored higher in neuroticism than males who AB (p < 0.05). There were personality differences between people who decided to bleach compared with those who did not want the bleaching, which was mainly in the extroversion factor. This stereotypes the patients, who could be described as more sociable, extroverted, and concerned about esthetics and cleanliness. The bleaching protocol, however, cannot modify any of the personality factors. It is important to understand a patient's behavior to meet their needs and to determine the type of patients who would like to have their teeth bleached.

The efficacy of laser-assisted in-office bleaching and home bleaching on sound and demineralized enamel.

PubMed

Ahrari, Farzaneh; Akbari, Majid; Mohammadpour, Sakineh; Forghani, Maryam

2015-12-30

This study investigated the effectiveness of laser-assisted in-office bleaching and home-bleaching in sound and demineralized enamel. The sample consisted of 120 freshly-extracted bovine incisors. Half of the specimens were stored in a demineralizing solution to induce white spot lesions. Following exposure to a tea solution for 7.5 days, the specimens were randomly assigned to 4 groups of 30 according to the type of enamel and the bleaching procedure employed. Groups 1 and 2 consisted of demineralized teeth subjected to in-office bleaching and home bleaching, whereas in groups 3 and 4, sound teeth were subjected to in-office and home bleaching, respectively. A diode laser (810 nm, 2 W, continuous wave, four times for 15 seconds each) was employed for assisting the in-office process. The color of the specimens was measured before (T1) and after (T2) staining and during (T3) and after (T4) the bleaching procedures using a spectrophotometer. The color change (ΔE) between different treatments stages was compared among the groups. There were significant differences in the color change between T2 and T3 (ΔE T2-T3) and T2 and T4 (ΔE T2-T4) stages among the study groups (p<0.05). Pairwise comparison by Duncan test revealed that both ΔET2-T3 and ΔET2-T4 were significantly greater in demineralized teeth submitted to laser-assisted in-office bleaching (group 1) as compared to the other groups (P< 0.05). Laser-assisted in-office bleaching could provide faster and greater whitening effect than home bleaching on stained demineralized enamel, but both procedures produced comparable results on sound teeth.

Recovery of cat retinal ganglion cell sensitivity following pigment bleaching.

PubMed Central

Bonds, A B; Enroth-Cugell, C

1979-01-01

1. The threshold illuminance for small spot stimulation of on-centre cat retinal ganglion cells was plotted vs. time after exposure to adapting light sufficiently strong to bleach significant amounts of rhodopsin. 2. When the entire receptive field of an X- or Y-type ganglion cell is bleached by at most 40%, recovery of the cell's rod-system proceeds in two phases: an early relatively fast one during which the response appears transient, and a late, slower one during which responses become more sustained. Log threshold during the later phase is well fit by an exponential in time (tau = 11.5-38 min). 3. After bleaches of 90% of the underlying pigment, threshold is cone-determined for as long as 40 min. Rod threshold continues to decrease for at least 85 min after the bleach. 4. The rate of recovery is slower after strong than after weak bleaches; 10 and 90% bleaches yield time constants for the later phase of 11.5 and 38 min, respectively. This contrasts with an approximate time constant of 11 min for rhodopsin regeneration following any bleach. 5. The relationship between the initial elevation of log rod threshold extrapolated from the fitted exponential curves and the initial amount of pigment bleached is monotonic, but nonlinear. 6. After a bleaching exposure, the maintained discharge is initially very regular. The firing rate first rises, then falls to the pre-bleach level, with more extended time courses of change in firing rate after stronger exposures. The discharge rate is restored before threshold has recovered fully. 7. The change in the response vs. log stimulus relationship after bleaching is described as a shift of the curve to the right, paired with a decrease in slope of the linear segment of the curve. PMID:521963

Introducing Students to Bio-Inspiration and Biomimetic Design: A Workshop Experience

ERIC Educational Resources Information Center

Santulli, Carlo; Langella, Carla

2011-01-01

In recent years, bio-inspired approach to design has gained considerable interest between designers, engineers and end-users. However, there are difficulties in introducing bio-inspiration concepts in the university curriculum in that they involve multi-disciplinary work, which can only possibly be successfully delivered by a team with integrated…

The effect of long-term use of tooth bleaching products on the human enamel surface.

PubMed

Polydorou, Olga; Scheitza, Sophia; Spraul, Mathias; Vach, Kirstin; Hellwig, Elmar

2018-01-01

The aim of this in vitro study was to evaluate the long-term effect of bleaching on human enamel. Four groups of enamel specimens were prepared (n = 20): group 1: bleaching with Opalescence Boost [40% hydrogen peroxide (H 2 O 2 ), 3 × 20 min/week]; group 2: control group (the specimens were stored in human saliva); group 3: beaching with Vivastyle Paint on Plus (6% H 2 O 2 , 2 × 10 min/day), and group 4: bleaching with Opalescence PF 16% [16% carbamide peroxide (CP), 6 h/day]. After each bleaching session the specimens were stored in human saliva. Knoop microhardness and surface roughness were measured: before bleaching, after 2-week and after 8-week bleaching. After 2-week treatment, surface roughness was significantly increased in all experimental groups (p < 0.05), while among them no significant difference was found (p > 0.05). The roughness changes exerted after 8-week bleaching were not significantly higher than the ones after 2 weeks (p > 0.05). After 8-week treatment, the increase in roughness caused by 16% CP was significantly higher (p < 0.05) than the one caused by 40% H 2 O 2 . Microhardness increased in all groups including control; however, only 40% H 2 O 2 increased the microhardness significantly (p < 0.05). The effect of bleaching on enamel was not shown to be dependent on the method or the H 2 O 2 concentration. Bleaching with CP 16% resulted in higher roughness than bleaching with H 2 O 2 , while 40% H 2 O 2 caused the higher microhardness increase. The present study showed that in-office bleaching with 40% H 2 O 2 seems to be at least as safe as home bleaching as far as their effects on human enamel are concerned.

In vitro Assessment of Influence of Various Bleaching Protocols on the Strength of Ceramic Orthodontic Brackets bonded to Bleached Tooth Surface: A Comparative Study.

PubMed

Iska, Divya; Devanna, Raghu; Singh, Madhvi; Chitumalla, Rajkiran; Balasubramanian, Sai C Bala; Goutam, Manish

2017-12-01

Esthetics is one of the common issues because of which patients consult dental orthodontic treatment. Two ways of tooth bleaching are available these days, which includes in-office bleach and home bleach. Various bleaching protocols are available these days for treating the tooth surfaces. Hence, we planned the present study for investigating the impact of various intracoronal bleaching protocols on shear bond strength of ceramic brackets bonded to tooth surface after bleaching. The present study included assessment of 100 extracted maxillary central incisors with the integrated buccal surface. A resin block was made and individual teeth were embedded in each block. Root canal therapy procedure was performed in all the teeth, after which 2 mm short of tooth apex up to the level of cementoenamel junction, removal of the root canal filling was done. All the samples were broadly divided into four study groups with 25 samples in each group. Bleaching procedure was carried in all the samples intracoronally followed by testing of shear bond strength using universal force testing machine. Following the modified adhesive remnant index (AI), assessment of remaining adhesive on the brackets was done. All the results were compiled and analyzed by Statistical Package for the Social Sciences (SPSS) software version 17.0. In the control group, mean shear bond strength was found to be 17.9 MPa. While comparing the carbamide peroxide (CP) group with sodium perborate study group, we observed a statistically significant difference. Nonsignificant results were obtained while comparing the shear bond strength in between sodium perborate group and hydrogen peroxide (HP) group. Intracoronal bleaching does affect the shear bond strength of ceramic brackets. Sodium perborate bleaching influences shear bond strength more strongly than other bleaching agents such as CP and HP. In patients undergoing orthodontic treatment, HP is a preferred agent where bleaching has to be followed by orthodontic bonding to the tooth surface.

Multifocal ERG reveals long distance effects of a local bleach in the retina.

PubMed

Kretschmann, U; Tornow, R P; Zrenner, E

1998-06-01

To examine the distribution of ERG-activity in the central visual field after local bleaching of the fovea, multifocal electroretinograms were recorded in eight normal volunteers before, during and after recurrent light exposure. During bleaching (90% bleached pigment), the response density (scalar product) of the foveal area (0-2 degrees eccentricity) decreased from 10.7 +/- 3.5 to 4.1 +/- 1.9 nV/degree2 (P < 0.001). The average activity in the extrafoveal macular area was unchanged, while the amplitudes were frequently (in 53 of 54 areas) enhanced at 5-30.5 degrees eccentricity. Here the average response density changed from 3.1 +/- 0.9 to 3.5 +/- 1.0 nV/degree2 (P < 0.001). A fast recovery of foveal responses after cessation of bleaching occurred. Besides a strong decrease of response in the directly bleached area, local bleaching led to enhanced activity mainly 3-27 degrees distant from the bleached area.

Design of pyrolysis reactor for production of bio-oil and bio-char simultaneously

NASA Astrophysics Data System (ADS)

Aladin, Andi; Alwi, Ratna Surya; Syarif, Takdir

2017-05-01

The residues from the wood industry are the main contributors to biomass waste in Indonesia. The conventional pyrolysis process, which needs a large energy as well as to produce various toxic chemical to the environment. Therefore, a pyrolysis unit on the laboratory scale was designed that can be a good alternative to achieve zero-waste and low energy cost. In this paper attempts to discuss design and system of pyrolysis reactor to produce bio-oil and bio-char simultaneously.

A model for prediction of color change after tooth bleaching based on CIELAB color space

NASA Astrophysics Data System (ADS)

Herrera, Luis J.; Santana, Janiley; Yebra, Ana; Rivas, María. José; Pulgar, Rosa; Pérez, María. M.

2017-08-01

An experimental study aiming to develop a model based on CIELAB color space for prediction of color change after a tooth bleaching procedure is presented. Multivariate linear regression models were obtained to predict the L*, a*, b* and W* post-bleaching values using the pre-bleaching L*, a*and b*values. Moreover, univariate linear regression models were obtained to predict the variation in chroma (C*), hue angle (h°) and W*. The results demonstrated that is possible to estimate color change when using a carbamide peroxide tooth-bleaching system. The models obtained can be applied in clinic to predict the colour change after bleaching.

In vitro demineralization of tooth enamel subjected to two whitening regimens.

PubMed

Ogura, Kayoko; Tanaka, Reina; Shibata, Yo; Miyazaki, Takashi; Hisamitsu, Hisashi

2013-07-01

The resistance of bleached enamel to demineralization has not been elucidated fully. In this study, the authors aimed to examine the level of in vitro demineralization of human tooth enamel after bleaching by using two common bleaching regimens: home bleaching (HB) and office bleaching (OB) with photoirradiation. The authors bleached teeth to equivalent levels by means of the two bleaching regimens. They used fluorescence spectroscopy to measure the reduction in enamel density and the release of calcium into solution after storing the treated teeth in a demineralizing solution for two weeks. They also visualized and quantified mineral distribution in demineralized bleached enamel over time by using a desktop microcomputed-tomographic analyzer. Enamel subjected to HB or to photoirradiation without bleaching showed increased demineralization. In contrast, enamel treated with OB was more resistant to demineralization. This resistance to demineralization in teeth treated with OB presumably is due to peroxide's permeating to deeper layers of enamel before being activated by photoirradiation, which enhances mineralization. The mineral distribution pattern of enamel after treatment plays a critical role in providing resistance to demineralization in whitened teeth. OB confers to enamel significant resistance to in vitro demineralization. Dentists should supervise the nightguard HB process.

Severity of the 1998 and 2005 bleaching events in Venezuela, southern Caribbean.

PubMed

Rodríguez, Sebastián; Cróquer, Aldo; Bone, David; Bastidas, Carolina

2010-10-01

This study describes the severity of the 2005 bleaching event at 15 reef sites across Venezuela and compares the 1998 and 2005 bleaching events at one of them. During August and September 2005, bleached corals were first observed on oceanic reefs rather than coastal reefs, affecting 1 to 4% of coral colonies in the community (3 reef sites, n = 736 colonies). At that time, however, no bleached corals were recorded along the eastern coast of Venezuela, an area of seasonal upwelling (3 reefs, n = 181 colonies). On coastal reefs, bleaching started in October but highest levels were reached in November 2005 and January 2006, when 16% of corals were affected among a wide range of taxa (e.g. scleractinians, octocorals, Millepora and zoanthids). In the Acropora habitats of Los Roques (an oceanic reef),no bleached was recorded in 2005 (four sites,n = 643 colonies). At Cayo Sombrero, a coastal reef site, bleaching was less severe in 1998 than in 2005 (9% of the coral colonies involving 2 species vs. 26% involving 23 species, respectively). Our results indicate that bleaching was more severe in 2005 than in 1998 on Venezuelan reefs; however, no mass mortality was observed in either of these two events.

Resistant-hemicelluloses toward successive chemical treatment during cellulose fibre extraction

NASA Astrophysics Data System (ADS)

Naqiya, F. M. Z.; Ahmad, I.; Airianah, O. B.

2018-04-01

Lignocellulosic materials have high demand bio-polymers industries as it is rich in cellulose but other residues that still remain in the extracted cellulose might influence the ability of cellulose-rich material to interact with other polymers. In this study, cellulose fibre was extracted from oil palm frond (OPF) using alkali and bleaching treatment. The morphological changes of each sample after every treatment was observed using Scanning Electron Microscope (SEM) and was further chemically extracted and quantitatively evaluated via spectrophotometric method. The non-cellulosic component was found predominantly contained hemicelluloses and these remaining hemicelluloses were hydrolysed and the monosaccharides of hemicelluloses were visualised by Thin Layer Chromatography (TLC). Xylose, arabinose, mannose and glucose were detected and therefore, it is suggested that the plausible type of resistant-hemicelluloses in OPF extracted fibre are arabinoxylan, glucomannan and/or glucan.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Chongqi; Harbich, Wolfgang; Sementa, Luca

Ligand-protected Au clusters are non-bleaching fluorescence markers in bio- and medical applications. We show that their fluorescence is an intrinsic property of the Au cluster itself. We find a very intense and sharp fluorescence peak located at λ =739.2 nm (1.68 eV) for Au20 clusters in a Ne matrix held at 6 K. The fluorescence reflects the HOMO-LUMO diabatic bandgap of the cluster. The cluster shows a very rich absorption fine structure reminiscent of well defined molecule-like quantum levels. These levels are resolved since Au20 has only one stable isomer (tetrahedral), therefore our sample is mono-disperse in cluster size andmore » conformation. Density-functional theory (DFT) and time-dependent DFT calculations clarify the nature of optical absorptionand predict both main absorption peaks and intrinsic fluorescence in good agreement with experiment.« less

Redefining thermal regimes to design reserves for coral reefs in the face of climate change.

PubMed

Chollett, Iliana; Enríquez, Susana; Mumby, Peter J

2014-01-01

Reef managers cannot fight global warming through mitigation at local scale, but they can use information on thermal patterns to plan for reserve networks that maximize the probability of persistence of their reef system. Here we assess previous methods for the design of reserves for climate change and present a new approach to prioritize areas for conservation that leverages the most desirable properties of previous approaches. The new method moves the science of reserve design for climate change a step forwards by: (1) recognizing the role of seasonal acclimation in increasing the limits of environmental tolerance of corals and ameliorating the bleaching response; (2) using the best proxy for acclimatization currently available; (3) including information from several bleaching events, which frequency is likely to increase in the future; (4) assessing relevant variability at country scales, where most management plans are carried out. We demonstrate the method in Honduras, where a reassessment of the marine spatial plan is in progress.

Redefining Thermal Regimes to Design Reserves for Coral Reefs in the Face of Climate Change

PubMed Central

Chollett, Iliana; Enríquez, Susana; Mumby, Peter J.

2014-01-01

Reef managers cannot fight global warming through mitigation at local scale, but they can use information on thermal patterns to plan for reserve networks that maximize the probability of persistence of their reef system. Here we assess previous methods for the design of reserves for climate change and present a new approach to prioritize areas for conservation that leverages the most desirable properties of previous approaches. The new method moves the science of reserve design for climate change a step forwards by: (1) recognizing the role of seasonal acclimation in increasing the limits of environmental tolerance of corals and ameliorating the bleaching response; (2) using the best proxy for acclimatization currently available; (3) including information from several bleaching events, which frequency is likely to increase in the future; (4) assessing relevant variability at country scales, where most management plans are carried out. We demonstrate the method in Honduras, where a reassessment of the marine spatial plan is in progress. PMID:25333380

In vitro comparison of an Er:YAG laser-activated bleaching system with different light-activated bleaching systems for color change, surface roughness, and enamel bond strength.

PubMed

Ergin, Esra; Ruya Yazici, A; Kalender, Bercem; Usumez, Aslihan; Ertan, Atilla; Gorucu, Jale; Sari, Tugrul

2018-06-02

To compare an Er:YAG laser-activated bleaching system with different light-activated in-office bleaching systems for color change, surface roughness, and post-bleaching enamel bond strength. 51 enamel slabs were prepared from the sound buccal enamel of extracted bovine teeth. The teeth were randomly divided into three groups according to different light-activated office bleaching systems (n = 17): diode laser (Epic, Biolase) (940 nm, 7 W, continuous mode), Er:YAG laser (LightWalker, Fotona) (2940 nm, 50 mJ, 10 Hz, 1000 μs), and LED (Radii Plus) (440-480 nm, 1500 mW/cm 2 ). All systems were used with their compatible bleaching agents according to manufacturers' recommendations. The tooth color and surface roughness (Ra) were assessed at baseline and after bleaching using a spectrophotometer and a surface profilometer, respectively. The color change was determined by the CIE L*a*b* system (ΔE, ΔL*, Δa*, Δb*). Kruskal-Wallis test was used for color change whereas Kruskal-Wallis and Wilcoxon tests were used to analyze the roughness data. For shear bond strength test (SBS), composite cylinders were bonded on bleached enamel samples 14 days after bleaching procedures and stored in water (37 °C). Specimens were then debonded with a universal testing machine at 1 mm/min and data were analyzed by using Kruskal-Wallis test. All the tested bleaching systems were effective on color change (ΔE > 3.3) and produced similar color change (p > 0.05). There were no significant differences among the Ra values of the groups neither at baseline nor after bleaching (p > 0.05). However, comparing the baseline and after bleaching Ra values, a significant increase was observed for all tested groups (p < 0.05). Significant differences were also found among all systems for SBS (p < 0.05). The highest values were obtained in Er:YAG group, whereas the LED group revealed the lowest values (p < 0.05). All tested bleaching systems were effective on tooth whitening, whereas they all led to an increase on surface roughness. Although the current Er:YAG laser-activated bleaching system did not differ from other tested bleaching systems according to color change and surface roughness, it appears to provide better results in terms of SBS.

Changes in Caribbean coral disease prevalence after the 2005 bleaching event.

PubMed

Cróquer, Aldo; Weil, Ernesto

2009-11-16

Bleaching events and disease epizootics have increased during the past decades, suggesting a positive link between these 2 causes in producing coral mortality. However, studies to test this hypothesis, integrating a broad range of hierarchical spatial scales from habitats to distant localities, have not been conducted in the Caribbean. In this study, we examined links between bleaching intensity and disease prevalence collected from 6 countries, 2 reef sites for each country, and 3 habitats within each reef site (N = 6 x 2 x 3 = 36 site-habitat combinations) during the peak of bleaching in 2005 and a year after, in 2006. Patterns of disease prevalence and bleaching were significantly correlated (Rho = 0.58, p = 0.04). Higher variability in disease prevalence after bleaching occurred among habitats at each particular reef site, with a significant increase in prevalence recorded in 4 of the 10 site-habitats where bleaching was intense and a non-significant increase in disease prevalence in 18 out of the 26 site-habitats where bleaching was low to moderate. A significant linear correlation was found (r = 0.89, p = 0.008) between bleaching and the prevalence of 2 virulent diseases (yellow band disease and white plague) affecting the Montastraea species complex. Results of this study suggest that if bleaching events become more intense and frequent, disease-related mortality of Caribbean coral reef builders could increase, with uncertain effects on coral reef resilience.

Bleaching susceptibility and recovery of Colombian Caribbean corals in response to water current exposure and seasonal upwelling.

PubMed

Bayraktarov, Elisa; Pizarro, Valeria; Eidens, Corvin; Wilke, Thomas; Wild, Christian

2013-01-01

Coral bleaching events are globally occurring more frequently and with higher intensity, mainly caused by increases in seawater temperature. In Tayrona National Natural Park (TNNP) in the Colombian Caribbean, local coral communities are subjected to seasonal wind-triggered upwelling events coinciding with stronger water currents depending on location. This natural phenomenon offers the unique opportunity to study potential water current-induced mitigation mechanisms of coral bleaching in an upwelling influenced region. Therefore, coral bleaching susceptibility and recovery patterns were compared during a moderate and a mild bleaching event in December 2010 and 2011, and at the end of the subsequent upwelling periods at a water current-exposed and -sheltered site of an exemplary bay using permanent transect and labeling tools. This was accompanied by parallel monitoring of key environmental variables. Findings revealed that in 2010 overall coral bleaching before upwelling was significantly higher at the sheltered (34%) compared to the exposed site (8%). Whereas 97% of all previously bleached corals at the water current-exposed site had recovered from bleaching by April 2011, only 77% recovered at the sheltered site, but 12% had died there. In December 2011, only mild bleaching (<10% at both sites) was observed, but corals recovered significantly at both sites in the course of upwelling. No differences in water temperatures between sites occurred, but water current exposure and turbidity were significantly higher at the exposed site, suggesting that these variables may be responsible for the observed site-specific mitigation of coral bleaching. This indicates the existence of local resilience patterns against coral bleaching in Caribbean reefs.

Effect of coffe and a cola-based soft drink on the color stability of bleached bovine incisors considering the time elapsed after bleaching

PubMed Central

PIROLO, Rodrigo; MONDELLI, Rafael Francisco Lia; CORRER, Gisele Maria; GONZAGA, Carla Castiglia; FURUSE, Adilson Yoshio

2014-01-01

There is no consensus about the waiting time necessary for the patient to start consuming beverages containing colorants again after bleaching. Objective: To evaluate the influence of beverages with coloring agents on bleached bovine incisors considering the time elapsed after bleaching. Materials and methods: Sixty bovine incisors were bleached with 35% hydrogen peroxide for in-office use (Whiteness HP Max) and divided into 10 groups. The color was evaluated with a spectrophotometer (Spectro Shade MICRO) before and after bleaching, employing the CIE-Lab system. After bleaching, the teeth were exposed for 5 min to coffee or cola-based soft drink (CBSD) at different periods after bleaching: 10 min, 1 h, 24 h, 48 h, and 72 h. Color (∆E) and lightness (∆L) variations were obtained from the CIE-Lab coordinates. Data were subjected to two-way ANOVA and Tukey HSD tests (p<0.05). Results: Significant differences were observed between groups for both the ∆L and ∆E values (p<0.001). All specimens presented a decrease in brightness (negative ∆L). The highest ∆E values were observed for teeth stained with a CBSD at 10 min and 1 h (4.12 and 4.16, respectively). Teeth pigmented with coffee presented ∆E values below 3.3 units for all evaluation times. Conclusion: The exposure to coffee after bleaching causes less color changes than the exposure to a CBSD regardless of the time after bleaching. PMID:25075672

Bleaching Susceptibility and Recovery of Colombian Caribbean Corals in Response to Water Current Exposure and Seasonal Upwelling

PubMed Central

Bayraktarov, Elisa; Pizarro, Valeria; Eidens, Corvin; Wilke, Thomas; Wild, Christian

2013-01-01

Coral bleaching events are globally occurring more frequently and with higher intensity, mainly caused by increases in seawater temperature. In Tayrona National Natural Park (TNNP) in the Colombian Caribbean, local coral communities are subjected to seasonal wind-triggered upwelling events coinciding with stronger water currents depending on location. This natural phenomenon offers the unique opportunity to study potential water current-induced mitigation mechanisms of coral bleaching in an upwelling influenced region. Therefore, coral bleaching susceptibility and recovery patterns were compared during a moderate and a mild bleaching event in December 2010 and 2011, and at the end of the subsequent upwelling periods at a water current-exposed and -sheltered site of an exemplary bay using permanent transect and labeling tools. This was accompanied by parallel monitoring of key environmental variables. Findings revealed that in 2010 overall coral bleaching before upwelling was significantly higher at the sheltered (34%) compared to the exposed site (8%). Whereas 97% of all previously bleached corals at the water current-exposed site had recovered from bleaching by April 2011, only 77% recovered at the sheltered site, but 12% had died there. In December 2011, only mild bleaching (<10% at both sites) was observed, but corals recovered significantly at both sites in the course of upwelling. No differences in water temperatures between sites occurred, but water current exposure and turbidity were significantly higher at the exposed site, suggesting that these variables may be responsible for the observed site-specific mitigation of coral bleaching. This indicates the existence of local resilience patterns against coral bleaching in Caribbean reefs. PMID:24282551

Tooth bleaching and young adults in Nigeria: knowledge, experiences and intention.

PubMed

Azodo, C C; Ogbomo, A C; Agbor, M A

2012-12-01

To assess the knowledge, experiences and intention to have tooth bleaching among young adults studying in a Nigerian University. A cross-section of part-time undergraduate students of University of Benin, Benin City, Nigeria were studied in 2010 using a self-administered questionnaire. About three-quarters 289 (72.4%) of the respondents reported awareness of at least one cause of tooth discoloration. A total of 143 (35.8%) of the respondents have heard of tooth bleaching with main sources of information being friends/relatives, dentists and the internet. One-third 132 (33.1%) of the respondents correctly identified that the aim of tooth bleaching was to make the teeth whiter. The respondents that had correct knowledge about mechanism, duration and complications of tooth bleaching were 51 (12.8%), 25 (6.3%) and 35 (8.8%) respectively. The major perceived benefits of tooth bleaching reported by the respondents were self confidence boost 152 (38.1%) and improvement of one's beauty 107 (26.8%). Out of the 68 (17.0%) respondents that have attempted tooth bleaching, 36 (52.9%) used tooth whitening toothpaste. Out of the 151 (37.8%) respondents that expressed intention of having tooth bleaching procedure, 32 (21.2%) would pursue the course, no matter the cost. In the studied population, knowledge of tooth discoloration was high, awareness and experiences of tooth bleaching were low but significant number expressed intention of having tooth bleaching. It is important that dentists increase oral health information particularly tooth bleaching information accessibility to the young adult population to improve the knowledge and prevent adverse effects.

21 CFR 582.1975 - Bleached beeswax.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Bleached beeswax. 582.1975 Section 582.1975 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1975 Bleached beeswax. (a) Product. Bleached beeswax (white wax). (b) Conditions of use...

40 CFR 430.20 - Applicability; description of the bleached papergrade kraft and soda subcategory.

Code of Federal Regulations, 2010 CFR

2010-07-01

... bleached papergrade kraft and soda subcategory. 430.20 Section 430.20 Protection of Environment... POINT SOURCE CATEGORY Bleached Papergrade Kraft and Soda Subcategory § 430.20 Applicability; description of the bleached papergrade kraft and soda subcategory. The provisions of this subpart apply to...

Coral Diseases Following Massive Bleaching in 2005 Cause 60 Percent Decline in Coral Cover and Mortality of the Threatened Species, Acropora Palmata, on Reefs in the U.S. Virgin Islands

USGS Publications Warehouse

Rogers, Caroline S.

2008-01-01

Record-high seawater temperatures and calm seas in the summer of 2005 led to the most severe coral bleaching (greater than 90 percent bleached coral cover) ever observed in the U.S. Virgin Islands (USVI) (figs. 1 and 2). All but a few coral species bleached, including the threatened species, Acropora palmata. Bleaching was seen from the surface to depths over 20 meters.

Tooth-bleaching procedures and their controversial effects: A literature review

PubMed Central

Alqahtani, Mohammed Q.

2014-01-01

Aim This review article will help clinicians improve their understanding of the history of bleaching procedures, bleaching types, components, mechanisms, and their effects on soft tissue, tooth structures, resin composite, and bonding. Methods The controversial issues about bleaching procedures and their effects are reviewed. Additionally, the consequences of pre- and post-bleaching on the bonding potential of composite resin restorations to tooth structure are discussed. Conclusion The overall goal of the paper is to help reduce risks for patients. PMID:25408594

Methodology for Designing and Developing a New Ultra-Wideband Antenna Based on Bio-Inspired Optimization Techniques

DTIC Science & Technology

2017-11-01

ARL-TR-8225 ● NOV 2017 US Army Research Laboratory Methodology for Designing and Developing a New Ultra-Wideband Antenna Based...Research Laboratory Methodology for Designing and Developing a New Ultra-Wideband Antenna Based on Bio-Inspired Optimization Techniques by...SUBTITLE Methodology for Designing and Developing a New Ultra-Wideband Antenna Based on Bio-Inspired Optimization Techniques 5a. CONTRACT NUMBER

Trace elementary concentration in enamel after dental bleaching using HI-ERDA

NASA Astrophysics Data System (ADS)

Added, N.; Rizzutto, M. A.; Curado, J. F.; Francci, C.; Markarian, R.; Mori, M.

2006-08-01

Changes of elementary concentrations in dental enamel after a bleaching treatment with different products, is presented, with special focus on the oxygen contribution. Concentrations for Ca, P, O and C and some other trace elements were obtained for enamel of bovine incisor teeth by HI-ERDA measurements using a 35Cl incident beam and an ionization chamber. Five groups of teeth with five samples each were treated with a different bleaching agents. Each tooth had its crown sectioned in two halves, one for bleaching test and one the other used as a control. Average values of C/Ca, O/Ca, F/Ca enrichment factors were found. The comparison between bleached and non-bleached halves indicates that bleaching treatment did not affect the mineral structure when low-concentration whitening systems were used. The almost constant oxygen concentration in enamel, suggests little changes due to whitening therapy.

Sodium Hydroxide and Calcium Hydroxide Hybrid Oxygen Bleaching with System

NASA Astrophysics Data System (ADS)

Doelle, K.; Bajrami, B.

2018-01-01

This study investigates the replacement of sodium hydroxide in the oxygen bleaching stage using a hybrid system consisting of sodium hydroxide calcium hydroxide. Commercial Kraft pulping was studied using yellow pine Kraft pulp obtained from a company in the US. The impact of sodium hydroxide, calcium hydroxide hybrid system in regard to concentration, reaction time and temperature for Kraft pulp was evaluated. The sodium hydroxide and calcium hydroxide dosage was varied between 0% and 15% based on oven dry fiber content. The bleaching reaction time was varied between 0 and 180 minutes whereas the bleaching temperature ranged between 70 °C and 110 °C. The ability to bleach pulp was measured by determining the Kappa number. Optimum bleaching results for the hybrid system were achieved with 4% sodium hydroxide and 2% calcium hydroxide content. Beyond this, the ability to bleach pulp decreased.

21 CFR 872.6475 - Heat source for bleaching teeth.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Heat source for bleaching teeth. 872.6475 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6475 Heat source for bleaching teeth. (a) Identification. A heat source for bleaching teeth is an AC-powered device that consists of a...

21 CFR 872.6475 - Heat source for bleaching teeth.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Heat source for bleaching teeth. 872.6475 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6475 Heat source for bleaching teeth. (a) Identification. A heat source for bleaching teeth is an AC-powered device that consists of a...

21 CFR 872.6475 - Heat source for bleaching teeth.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Heat source for bleaching teeth. 872.6475 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6475 Heat source for bleaching teeth. (a) Identification. A heat source for bleaching teeth is an AC-powered device that consists of a...

21 CFR 872.6475 - Heat source for bleaching teeth.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Heat source for bleaching teeth. 872.6475 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6475 Heat source for bleaching teeth. (a) Identification. A heat source for bleaching teeth is an AC-powered device that consists of a...

21 CFR 872.6475 - Heat source for bleaching teeth.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Heat source for bleaching teeth. 872.6475 Section... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6475 Heat source for bleaching teeth. (a) Identification. A heat source for bleaching teeth is an AC-powered device that consists of a...

Excess seawater nutrients, enlarged algal symbiont densities and bleaching sensitive reef locations: 2. A regional-scale predictive model for the Great Barrier Reef, Australia.

PubMed

Wooldridge, Scott A; Heron, Scott F; Brodie, Jon E; Done, Terence J; Masiri, Itsara; Hinrichs, Saskia

2017-01-15

A spatial risk assessment model is developed for the Great Barrier Reef (GBR, Australia) that helps identify reef locations at higher or lower risk of coral bleaching in summer heat-wave conditions. The model confirms the considerable benefit of discriminating nutrient-enriched areas that contain corals with enlarged (suboptimal) symbiont densities for the purpose of identifying bleaching-sensitive reef locations. The benefit of the new system-level understanding is showcased in terms of: (i) improving early-warning forecasts of summer bleaching risk, (ii) explaining historical bleaching patterns, (iii) testing the bleaching-resistant quality of the current marine protected area (MPA) network (iv) identifying routinely monitored coral health attributes, such as the tissue energy reserves and skeletal growth characteristics (viz. density and extension rates) that correlate with bleaching resistant reef locations, and (v) targeting region-specific water quality improvement strategies that may increase reef-scale coral health and bleaching resistance. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Effect of in-office bleaching agents on physical properties of dental composite resins.

PubMed

Mourouzis, Petros; Koulaouzidou, Elisabeth A; Helvatjoglu-Antoniades, Maria

2013-04-01

The physical properties of dental restorative materials have a crucial effect on the longevity of restorations and moreover on the esthetic demands of patients, but they may be compromised by bleaching treatments. The purpose of this study was to evaluate the effects of in-office bleaching agents on the physical properties of three composite resin restorative materials. The bleaching agents used were hydrogen peroxide and carbamide peroxide at high concentrations. Specimens of each material were prepared, cured, and polished. Measurements of color difference, microhardness, and surface roughness were recorded before and after bleaching and data were examined statistically by analysis of variance (ANOVA) and Tukey HSD post-hoc test at P < .05. The measurements showed that hue and chroma of silorane-based composite resin altered after the bleaching procedure (P < .05). No statistically significant differences were found when testing the microhardness and surface roughness of composite resins tested (P > .05). The silorane-based composite resin tested showed some color alteration after bleaching procedures. The bleaching procedure did not alter the microhardness and the surface roughness of all composite resins tested.

Large-amplitude internal waves benefit corals during thermal stress.

PubMed

Wall, M; Putchim, L; Schmidt, G M; Jantzen, C; Khokiattiwong, S; Richter, C

2015-01-22

Tropical scleractinian corals are particularly vulnerable to global warming as elevated sea surface temperatures (SSTs) disrupt the delicate balance between the coral host and their algal endosymbionts, leading to symbiont expulsion, mass bleaching and mortality. While satellite sensing of SST has proved a reliable predictor of coral bleaching at the regional scale, there are large deviations in bleaching severity and mortality on the local scale that are poorly understood. Here, we show that internal waves play a major role in explaining local coral bleaching and mortality patterns in the Andaman Sea. Despite a severe region-wide SST anomaly in May 2010, frequent upslope intrusions of cold sub-pycnocline waters due to breaking large-amplitude internal waves (LAIW) mitigated coral bleaching and mortality in shallow waters. In LAIW-sheltered waters, by contrast, bleaching-susceptible species suffered severe bleaching and total mortality. These findings suggest that LAIW benefit coral reefs during thermal stress and provide local refugia for bleaching-susceptible corals. LAIW are ubiquitous in tropical stratified waters and their swash zones may thus be important conservation areas for the maintenance of coral diversity in a warming climate. Taking LAIW into account can significantly improve coral bleaching predictions and provide a valuable tool for coral reef conservation and management. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Effects of hydrogen peroxide on the light reflectance and morphology of bovine enamel.

PubMed

Kwon, Y H; Huo, M S; Kim, K H; Kim, S K; Kim, Y J

2002-05-01

The purpose of this study was to examine the effects of a bleaching agent (30% hydrogen peroxide) on the surface of bovine enamel using a scanning electron microscope and a UV-VIS-NIR spectrophotometer. Five non-carious bovine incisors were bleached for 0, 1, 2 and 3 days using 30% hydrogen peroxide. The light reflectance spectrum was measured using a spectrophotometer with diffuse reflectance mode. Colour values and colour differences in the teeth were evaluated from the reflectance measurements with the CIE L*a*b* colour coordinate system. Surface alterations in the bleached and unbleached teeth were studied using a scanning electron microscope. The change of reflectance in the teeth was related to the change of colour. Most reflectance change occurred within a 1-day bleaching, and this result was confirmed by a CIE L*a*b* colour coordinate system. The colour differences in the bleached teeth were significant enough to be perceived by the observer's eye. The comparison of bleached to unbleached bovine enamel revealed that the bleached surface showed non-uniform slight morphological alterations, and it developed varying degrees of surface porosity. This study indicates that the bleached bovine teeth showed apparent colour differences as well as slight morphological alterations after bleaching.

Influence of Enamel Thickness on Bleaching Efficacy: An In-Depth Color Analysis

PubMed Central

Públio, Juliana do Carmo; D’Arce, Maria Beatriz Freitas; Catelan, Anderson; Ambrosano, Gláucia Maria Bovi; Aguiar, Flávio Henrique Baggio; Lovadino, José Roberto; Lima, Débora Alves Nunes Leite

2016-01-01

This study evaluated the influence of different enamel thicknesses and bleaching agents on treatment efficacy in-depth by spectrophotometry color analysis. Eighty bovine dental fragments were previously stained in black tea solution and randomly assigned into eight groups (n=10), 1.75mm dentin thickness and different enamel thicknesses as follows: 0.5mm, 1.0mm planned, 1.0mm unplanned (aprismatic enamel), and absence of enamel. The 10% carbamide peroxide (CP) and 35% hydrogen peroxide (HP) bleaching gels were applied on the enamel surface following the manufacturer's recommendations. Color of underlying dentin was evaluated at four times: after staining with tea (baseline) and after each one of the three weeks of bleaching treatment, by CIE L*a*b* system using reflectance spectrophotometer (CM 700d, Konica Minolta). The ΔE, ΔL, Δa, and Δb values were recorded and subjected to repeated measures ANOVA and Tukey’s test (α=0.05). The results showed an increase on lightness (L*), with decreased redness (a*) and yellowness (b*). At first and second week, bleaching with CP showed higher whitening effectiveness compared to bleaching with HP and the presence of aprismatic enamel significantly reduced ΔE for bleaching with CP. After three weeks of bleaching, few differences were observed between CP and HP groups, and outer enamel layer caused no influence on bleaching effectiveness. Overall, both at-home and in-office bleaching treatments were effective and the presence of aprismatic enamel did not interfere on the whitening efficacy. PMID:27708725

Influence of Enamel Thickness on Bleaching Efficacy: An In-Depth Color Analysis.

PubMed

Públio, Juliana do Carmo; D'Arce, Maria Beatriz Freitas; Catelan, Anderson; Ambrosano, Gláucia Maria Bovi; Aguiar, Flávio Henrique Baggio; Lovadino, José Roberto; Lima, Débora Alves Nunes Leite

2016-01-01

This study evaluated the influence of different enamel thicknesses and bleaching agents on treatment efficacy in-depth by spectrophotometry color analysis. Eighty bovine dental fragments were previously stained in black tea solution and randomly assigned into eight groups (n=10), 1.75mm dentin thickness and different enamel thicknesses as follows: 0.5mm, 1.0mm planned, 1.0mm unplanned (aprismatic enamel), and absence of enamel. The 10% carbamide peroxide (CP) and 35% hydrogen peroxide (HP) bleaching gels were applied on the enamel surface following the manufacturer's recommendations. Color of underlying dentin was evaluated at four times: after staining with tea (baseline) and after each one of the three weeks of bleaching treatment, by CIE L*a*b* system using reflectance spectrophotometer (CM 700d, Konica Minolta). The ΔE, ΔL, Δa, and Δb values were recorded and subjected to repeated measures ANOVA and Tukey's test (α=0.05). The results showed an increase on lightness (L*), with decreased redness (a*) and yellowness (b*). At first and second week, bleaching with CP showed higher whitening effectiveness compared to bleaching with HP and the presence of aprismatic enamel significantly reduced ΔE for bleaching with CP. After three weeks of bleaching, few differences were observed between CP and HP groups, and outer enamel layer caused no influence on bleaching effectiveness. Overall, both at-home and in-office bleaching treatments were effective and the presence of aprismatic enamel did not interfere on the whitening efficacy.

Effects of Bleaching Agents Combined with Regular and Whitening Toothpastes on Surface Roughness and Mineral Content of Enamel.

PubMed

Attia, Mariana Lerner; Cavalli, Vanessa; do Espírito Santo, Ana Maria; Martin, Airton Abrahão; D'Arce, Maria Beatriz Freitas; Aguiar, Flávio Henrique Baggio; Lovadino, José Roberto; do Rego, Marcos Augusto; Cavalcanti, Andréa Nóbrega; Liporoni, Priscila Christiane Suzy

2015-07-01

The purpose of this study was to evaluate surface roughness and changes in the composition of enamel submitted to different bleaching protocols and toothbrushing with regular and whitening toothpastes. Bleaching treatment could promote morphological and chemical changes in enamel surface. Enamel blocks were randomized into nine groups (n=10) according to the bleaching treatment (no bleaching, control group; 6% hydrogen peroxide, HP; or 10% carbamide peroxide, CP) and toothpaste used (placebo, PL; regular, R; or whitening dentifrice, W). Bleaching was performed according to manufacturers' instructions and all groups were submitted to 30,000 cycles of simulated toothbrushing with toothpaste (PL, R, or W). Mineral content evaluation and enamel roughness were evaluated initially (T1), after bleaching (T2), and after toothbrushing (T3), using an energy-dispersive micro X-ray fluorescence spectrometer and profilometry, respectively. Data were statistically analyzed with two way ANOVA, Tukey, and Dunnett tests (5%). Enamel surface roughness was influenced by bleaching and toothbrushing. Surface roughness increased for the groups that brushed with the placebo dentifrice (CP+PL, HP+PL, C+PL) and for the control group that brushed with whitening dentifrice (C+W). Enamel Ca/P ratio decreased after bleaching, but toothbrushing, regardless of the dentifrice used, did not reduce the enamel mineral content. The bleaching treatment resulted in a decrease of enamel mineral content, but the studied dentifrices did not contribute to surface mineral loss.

In Situ and In Vitro Effects of Two Bleaching Treatments on Human Enamel Hardness.

PubMed

Henn-Donassollo, Sandrina; Fabris, Cristiane; Gagiolla, Morgana; Kerber, Ícaro; Caetano, Vinícius; Carboni, Vitor; Salas, Mabel Miluska Suca; Donassollo, Tiago Aurélio; Demarco, Flávio Fernando

2016-01-01

The aim of this study was to evaluate in vitro and in situ the effects of two bleaching treatments on human enamel surface microhardness. Sixty enamel slabs from recently extracted thirty molars were used. The specimens were polished with sandpapers under water-cooling. The enamel samples were randomly divided in four groups, treated with 10% hydrogen peroxide (HP) or Whitening Strips (WS) containing 10% hydrogen peroxide and using two conditions: in vitro or in situ model. For in situ condition, six volunteers wore an intra-oral appliance containing enamel slabs, while for in vitro condition the specimens were kept in deionized water after the bleaching protocols. The bleaching treatments were applied one-hour daily for 14 days. Similar amounts of bleaching agents were used in both conditions. Before and after bleaching treatments, microhardness was measured. Statistical analysis (ANOVA and Tukey test) showed that in the in situ condition there was no statistically significant microhardness reduction in the bleached enamel (p>0.05). Significant decrease in hardness was observed for enamel slabs bleached with both treatments in the in vitro condition (p<0.05). Regarding the bleaching agents, in situ results showed no difference between HP and WS, while in vitro WS produced the lowest hardness value. It could be concluded that there was no deleterious effect on enamel produced by any of the bleaching protocols used in the in situ model. The reduction of hardness was only observed in vitro.

Effects of the Ratio between Pigment and Bleaching Gel on the Fracture Resistance and Dentin Microhardness of endodontically treated Teeth.

PubMed

Galloza, Marina Og; Jordão-Basso, Keren Cf; Bandeca, Matheus C; Costa, Samuel O; Borges, Alvaro H; Tonetto, Mateus R; Tirintan, Fabio C; Keine, Kátia C; Kuga, Milton C

2017-11-01

The aim of this study was to evaluate the effects of bleaching gel using 35% hydrogen peroxide (HP), associated with red carmine pigment (RC), in the 3:1 or 1:1 ratio, on fracture resistance and dentin microhardness of endodontically treated teeth. A total of 40 lower incisors were endodontically treated and divided into four groups (n = 10), according to the bleaching protocol: G1 (HP3), 35% HP + RC (3:1); G2 (HP1), 35% HP + RC (1:1); G3 (positive), 38% HP; and G4 (negative), unbleached. Four dental bleaching sessions were performed. The dental crowns were restored after the last session and submitted to the fracture resistance test. Totally, 60 specimens from the endodontically treated lower incisor crowns were prepared to evaluate the effects on dentin microhardness. The analysis was measured (in Knoop) prior to and after the last dental bleaching session using similar bleaching protocols. G2 presented the lowest fracture resistance (p < 0.05). The other groups were similar to each other (p > 0.05). No difference was observed in the reduction of dentin microhardness among the groups (p > 0.05). A 1:1 ratio (bleaching gel:pigment) caused a significant fracture resistance reduction in relation to the other protocols. No effect on the dentin microhardness reduction was observed. The pigment addition to the bleaching agent accelerates the bleaching chemical reaction. However, no studies have evaluated the ideal proportion to optimize tooth bleaching.

Coral bleaching independent of photosynthetic activity.

PubMed

Tolleter, Dimitri; Seneca, François O; DeNofrio, Jan C; Krediet, Cory J; Palumbi, Stephen R; Pringle, John R; Grossman, Arthur R

2013-09-23

The global decline of reef-building corals is due in part to the loss of algal symbionts, or "bleaching," during the increasingly frequent periods of high seawater temperatures. During bleaching, endosymbiotic dinoflagellate algae (Symbiodinium spp.) either are lost from the animal tissue or lose their photosynthetic pigments, resulting in host mortality if the Symbiodinium populations fail to recover. The >1,000 studies of the causes of heat-induced bleaching have focused overwhelmingly on the consequences of damage to algal photosynthetic processes, and the prevailing model for bleaching invokes a light-dependent generation of toxic reactive oxygen species (ROS) by heat-damaged chloroplasts as the primary trigger. However, the precise mechanisms of bleaching remain unknown, and there is evidence for involvement of multiple cellular processes. In this study, we asked the simple question of whether bleaching can be triggered by heat in the dark, in the absence of photosynthetically derived ROS. We used both the sea anemone model system Aiptasia and several species of reef-building corals to demonstrate that symbiont loss can occur rapidly during heat stress in complete darkness. Furthermore, we observed damage to the photosynthetic apparatus under these conditions in both Aiptasia endosymbionts and cultured Symbiodinium. These results do not directly contradict the view that light-stimulated ROS production is important in bleaching, but they do show that there must be another pathway leading to bleaching. Elucidation of this pathway should help to clarify bleaching mechanisms under the more usual conditions of heat stress in the light. Copyright © 2013 Elsevier Ltd. All rights reserved.

The effect of species and colony size on the bleaching response of reef-building corals in the Florida Keys during the 2005 mass bleaching event

NASA Astrophysics Data System (ADS)

Brandt, M. E.

2009-12-01

Understanding the variation in coral bleaching response is necessary for making accurate predictions of population changes and the future state of reefs in a climate of increasing thermal stress events. Individual coral colonies, belonging to inshore patch reef communities of the Florida Keys, were followed through the 2005 mass bleaching event. Overall, coral bleaching patterns followed an index of accumulated thermal stress more closely than in situ temperature measurements. Eight coral species ( Colpophyllia natans, Diploria strigosa, Montastraea cavernosa, M. faveolata, Porites astreoides, P. porites, Siderastrea siderea, and Stephanocoenia intersepta), representing >90% of the coral colonies studied, experienced intense levels of bleaching, but responses varied. Bleaching differed significantly among species: Colpophyllia natans and Diploria strigosa were most susceptible to thermal stress, while Stephanocoenia intersepta was the most tolerant. For colonies of C. natans, M. faveolata, and S. siderea, larger colonies experienced more extensive bleaching than smaller colonies. The inshore patch reef communities of the Florida Keys have historically been dominated by large colonies of Montastraea sp. and Colpophyllia natans. These results provide evidence that colony-level differences can affect bleaching susceptibility in this habitat and suggest that the impact of future thermal stress events may be biased toward larger colonies of dominant reef-building species. Predicted increases in the frequency of mass bleaching and subsequent mortality may therefore result in significant structural shifts of these ecologically important communities.

Attitudes of final-year dental students to bleaching of vital and non-vital teeth in Cardiff, Cork, and Malmö.

PubMed

Hatherell, S; Lynch, C D; Burke, F M; Ericson, D; Gilmour, A S M

2011-04-01

The aim of this study was to determine attitudes of final-year dental students in Cardiff, Cork and Malmö towards tooth whitening. Following receipt of ethical approval, pre-piloted questionnaires were distributed to final-year dental students in Cork, Cardiff, and Malmö as close as possible to graduation. The questionnaire sought information relating to various opinions and attitudes towards the use of bleaching techniques including safety of bleaching, confidence in the provision of bleaching, recommendations to patients, teaching received, awareness of restrictions on the use of bleaching products and management of simulated clinical scenarios. Eighty three per cent (n = 116) of questionnaires were returned. Cork dental students had the most didactic teaching (2-h vital, 1-h non-vital bleaching) compared to Cardiff or Malmö students (0 h each). More Cork students regarded bleaching as safe (76%, n = 28) than Cardiff (70%, n = 32) or Malmö (36%, n = 12) students. More than 50% of Cork students feel they know enough about bleaching to provide it in practice, significantly more than Cardiff (< 25%) or Malmö (< 25%) students. The majority of students would provide vital bleaching after qualification (100% (n = 37) Cork; 82% (n = 27) Malmö; 76% (n = 35) Cardiff). In simulated clinical scenarios, more Cork students would propose bleaching treatments (89%n = 33) than Malmö (64%n = 21) or Cardiff (48%n= 22) students. Variations exist in the attitudes and approaches of three European dental schools towards bleaching. Dental students need to be best prepared to meet the needs of their future patients. © 2010 Blackwell Publishing Ltd.

Effects of the bleaching procedures on enamel micro-hardness: Plasma Arc and diode laser comparison.

PubMed

Nematianaraki, Saeid; Fekrazad, Reza; Naghibi, Nasim; Kalhori, Katayoun Am; Junior, Aldo Brugnera

2015-10-02

One of the major side effects of vital bleaching is the reduction of enamel micro-hardness. The purpose of this study was to evaluate the influence of two different bleaching systems, Plasma Arc and GaAlAs laser, on the enamel micro-hardness. 15 freshly extracted human third molars were sectioned to prepare 30 enamel blocks (5×5 mm). These samples were then randomly divided into 2 groups of 15 each (n=15): a plasma arc bleaching group (: 350-700 nm) + 35% Hydrogen Peroxide whitening gel and a laser bleaching group (GaAlAs laser, λ: 810 nm, P: 10 W, CW, Special Tip) + 35% Hydrogen Peroxide whitening gel. Samples were subjected to the Vickers micro-hardness test (VHN) at a load of 50 g for 15s before and after treatment. Data were statistically analyzed by a Mann-Whitney test (p≤0.05). In the GaAlAs laser group, the enamel micro-hardness was 618.2 before and was reduced to 544.6 after bleaching procedures. In the plasma arc group, the enamel micro-hardness was 644.8 before and 498.9 after bleaching. Although both techniques significantly reduced VHN, plasma arc bleaching resulted in a 22.62% reduction in VHN for enamel micro-hardness, whereas an 11.89% reduction in VHN was observed for laser bleaching; this difference is statistically significant (p<0.001). Both bleaching techniques reduced enamel micro-hardness, although the reduction is much less significant with the GaAlAs laser than with the plasma arc. Therefore GaAlAs laser bleaching has fewer harmful effects than plasma arc in respect to enamel micro-hardness reduction.

The Influence of Post Bleaching Treatments in Stain Absorption and Microhardness

PubMed Central

Moosavi, Horieh; Darvishzadeh, Fatemeh

2016-01-01

Objectives: This study investigated the effects of post bleaching treatments to prevent restaining and the change of enamel surface microhardness after dental bleaching in vitro. Methods: Sixty intact human incisor teeth were stained in tea solution and randomly assigned into four groups (n=15). Then samples were bleached for two weeks (8 hours daily) by 15% carbamide peroxide. Tooth color was determined both with a spectrophotometer and visually before bleaching (T1) and immediately after bleaching (T2). Next, it was applied in group 1 fluoride (Naf 2%) gel for 2 minutes, and in group 2 a fractional CO2 laser (10 mJ, 200 Hz, 10 s), and in group 3, nanohydroxyapatite gel for 2 minutes. The bleached teeth in group 4 remained untreated (control group). Then teeth placed in tea solution again. Color examinations were repeated after various post bleaching treatments (T3) and restaining with tea (T4) and color change values recorded. The microhardness was measured at the enamel surface of samples. Data was analyzed using ANOVA, Tukey HSD test and Dunnett T3 (α = 0.05). Results: Directly after bleaching (ΔE T3-T2), the treatment with nanohydroxyapatite showed significantly the least color lapse in colorimetric evaluation. In experimental groups, the color change between T3 and T4 stages (ΔE T4-T3) was significantly lower than control group (P < 0.05). Different methods of enamel treatment caused a significant increase in surface microhardness compared to control group (P < 0.05). Significance: Application of fluoride, fractional CO2 laser and nanohydroxyapatite as post bleaching treatments are suggested for prevention of stain absorption and increasing the hardening of bleached enamel. PMID:27099635

Effect of enamel sealants on tooth bleaching and on the color stability of the result.

PubMed

Corcodel, N; Hassel, A J; Sen, S; Saure, D; Rammelsberg, P; Lux, C J; Zingler, S

2017-04-01

The purpose of this in vitro study was to evaluate the effect of enamel sealants on bleaching of natural teeth by use of 40 % hydrogen peroxide in a dental surgery. The color stability of the results from bleaching was, furthermore, determined 10 months after the bleaching procedure. In a standardized setting, four sealants (Pro Seal ® , Light Bond™ Sealant, Protecto ® , and Clinpro™ XT Varnish) were applied to and removed from human teeth in accordance with the manufacturer's instructions. Natural teeth served as medium; half of the teeth were sealed and the others served as controls. Hydrogen peroxide gel (40 %; Opalescence Boost; Ultradent Products, South Jordan, UT, USA) was used as bleaching agent. Color measurement was performed with a spectroradiometer (Photoresearch PR670) before the bleaching process (T1) and 24 h (T2) and 10 months (T3) after bleaching. The spectroradiometer results were expressed by use of the Commission Internationale de l'Éclairage (CIE) L*a*b* color notation. The L*, a*, and b* values of the sealed and the unsealed surfaces were not significantly different at any time during the study (p > 0.05), irrespective of the sealant used. Ten months after the bleaching process, mean L*, a*, and b* values were lower than at 1-day post-bleaching; the mean value of ΔE between 1-day post-bleaching and 10 months post-bleaching was 2.46 (±3.1). The results of the study suggest that the effectiveness of professional tooth whitening is not appreciably affected by the application of the four sealants tested.

Improvement in rice straw pulp bleaching effluent quality by incorporating oxygen delignification stage prior to elemental chlorine-free bleaching.

PubMed

Kaur, Daljeet; Bhardwaj, Nishi K; Lohchab, Rajesh Kumar

2017-10-01

Environmental degradation by industrial and other developmental activities is alarming for imperative environmental management by process advancements of production. Pulp and paper mills are now focusing on using nonwood-based raw materials to protect forest resources. In present study, rice straw was utilized for pulp production as it is easily and abundantly available as well as rich in carbohydrates (cellulose and hemicelluloses). Soda-anthraquinone method was used for pulp production as it is widely accepted for agro residues. Bleaching process during paper production is the chief source of wastewater generation. The chlorophenolic compounds generated during bleaching are highly toxic, mutagenic, and bioaccumulative in nature. The objectives of study were to use oxygen delignification (ODL) stage prior to elemental chlorine-free (ECF) bleaching to reduce wastewater load and to study its impact on bleached pulp characteristics. ODL stage prior to ECF bleaching improved the optical properties of pulp in comparison to only ECF bleaching. When ODL stage was incorporated prior to bleaching, the tensile index and folding endurance of the pulp were found to be 56.6 ± 1.5 Nm/g and 140, respectively, very high in comparison to ECF alone. A potential reduction of 51, 57, 43, and 53% in BOD 3 , COD, color, and AOX, respectively was observed on adding the ODL stage compared to ECF only. Generation of chlorophenolic compounds was reduced significantly. Incorporation of ODL stage prior to bleaching was found to be highly promising for reducing the toxicity of bleaching effluents and may lead to better management of nearby water resources. Graphical abstract ᅟ.

The Influence of Post Bleaching Treatments in Stain Absorption and Microhardness.

PubMed

Moosavi, Horieh; Darvishzadeh, Fatemeh

2016-01-01

This study investigated the effects of post bleaching treatments to prevent restaining and the change of enamel surface microhardness after dental bleaching in vitro. Sixty intact human incisor teeth were stained in tea solution and randomly assigned into four groups (n=15). Then samples were bleached for two weeks (8 hours daily) by 15% carbamide peroxide. Tooth color was determined both with a spectrophotometer and visually before bleaching (T1) and immediately after bleaching (T2). Next, it was applied in group 1 fluoride (Naf 2%) gel for 2 minutes, and in group 2 a fractional CO2 laser (10 mJ, 200 Hz, 10 s), and in group 3, nanohydroxyapatite gel for 2 minutes. The bleached teeth in group 4 remained untreated (control group). Then teeth placed in tea solution again. Color examinations were repeated after various post bleaching treatments (T3) and restaining with tea (T4) and color change values recorded. The microhardness was measured at the enamel surface of samples. Data was analyzed using ANOVA, Tukey HSD test and Dunnett T3 (α = 0.05). Directly after bleaching (ΔE T3-T2), the treatment with nanohydroxyapatite showed significantly the least color lapse in colorimetric evaluation. In experimental groups, the color change between T3 and T4 stages (ΔE T4-T3) was significantly lower than control group (P < 0.05). Different methods of enamel treatment caused a significant increase in surface microhardness compared to control group (P < 0.05). Application of fluoride, fractional CO2 laser and nanohydroxyapatite as post bleaching treatments are suggested for prevention of stain absorption and increasing the hardening of bleached enamel.

Spectrophotometric analysis of discoloration and internal bleaching after use of different antibiotic pastes.

PubMed

Fundaoğlu Küçükekenci, Funda; Çakici, Fatih; Küçükekenci, Ahmet Serkan

2018-04-14

To investigate teeth's antibiotic-induced color differences after bleaching using two different techniques. One hundred twenty extracted maxillar human incisors were examined. The specimens were randomly divided into six groups, each receiving one of six antibiotic paste fillings: (1) triple antibiotic paste (TAP) with minocycline, (2) double antibiotic paste (DAP), (3) TAP with amoxicillin, (4) TAP with cefaclor, (5) TAP with doxycycline, and (6) no filling (control group). Spectrophotometric measurements were obtained at baseline and then during the first, second, and third weeks after paste placement. The specimens discolored by antibiotics pastes were randomly divided into two subgroups: (1) internal bleaching with hydrogen peroxide (H 2 O 2) and (2) internal bleaching with H 2 O 2 plus Nd-YAG laser irradiation. The ∆E value was calculated and analyzed using a two-way analysis of variance and post-hoc Tukey's test (α = 0.05). The ∆E for all groups showed color differences exceeding the perceptibility threshold (∆E ˃ 3.7) at all time points except in the control and DAP groups. Minocycline-induced TAP showed the most severe coronal discoloration (32.42). When the ∆E was examined, thermo/photo bleaching (22.01 ± 8.23) caused more bleaching than walking bleaching (19.73 ± 5.73) at every time point (P = 0.19). No group returned to the original color after bleaching (P < 0.05). Except for DAP, all antibiotic pastes caused discoloration. Internal bleaching with Nd-YAG laser can be useful for bleaching/removing this discoloration. For clinically successful final appearances, understanding the effects of bleaching procedures on antibiotic paste discoloration is important.

Bleaching of leaf litter and associated microfungi in subboreal and subalpine forests.

PubMed

Hagiwara, Yusuke; Matsuoka, Shunsuke; Hobara, Satoru; Mori, Akira S; Hirose, Dai; Osono, Takashi

2015-10-01

Fungal decomposition of lignin leads to the whitening, or bleaching, of leaf litter, especially in temperate and tropical forests, but less is known about such bleaching in forests of cooler regions, such as boreal and subalpine forests. The purposes of the present study were to examine the extent of bleached area on the surface of leaf litter and its variation with environmental conditions in subboreal and subalpine forests in Japan and to examine the microfungi associated with the bleaching of leaf litter by isolating fungi from the bleached portions of the litter. Bleached area accounted for 21.7%-32.7% and 2.0%-10.0% of total leaf area of Quercus crispula and Betula ermanii, respectively, in subboreal forests, and for 6.3% and 18.6% of total leaf area of B. ermanii and Picea jezoensis var. hondoensis, respectively, in a subalpine forest. In subboreal forests, elevation, C/N ratio and pH of the FH layer, and slope aspect were selected as predictor variables for the bleached leaf area. Leaf mass per area and lignin content were consistently lower in the bleached area than in the nonbleached area of the same leaves, indicating that the selective decomposition of acid unhydrolyzable residue (recalcitrant compounds such as lignin, tannins, and cutins) enhanced the mass loss of leaf tissues in the bleached portions. Isolates of a total of 11 fungal species (6 species of Ascomycota and 5 of Basidiomycota) exhibited leaf-litter-bleaching activity under pure culture conditions. Two fungal species (Coccomyces sp. and Mycena sp.) occurred in both subboreal and subalpine forests, which were separated from each other by approximately 1100 km.

Effect of laser-assisted bleaching with Nd:YAG and diode lasers on shear bond strength of orthodontic brackets.

PubMed

Mirhashemi, Amirhossein; Emadian Razavi, Elham Sadat; Behboodi, Sara; Chiniforush, Nasim

2015-12-01

The aim of the present study was to assess the effect of laser-assisted bleaching with neodymium:yttrium-aluminum-garnet (Nd:YAG) and diode lasers on shear bond strength (SBS) of orthodontic brackets. One hundred and four extracted human premolars were randomly divided into four groups: group 1: No bleaching applied (control group); group 2: Teeth bleached with 40 % hydrogen peroxide; group 3: Teeth treated with 30 % hydrogen peroxide activated with Nd:YAG laser (1064 nm, 2.5 W, 25 Hz, pulse duration of 100 μs, 6 mm distance); and group 4: Teeth treated with 30 % hydrogen peroxide activated with diode laser (810 nm, 1 W, CW, 6 mm distance). Equal numbers of teeth in groups 2, 3, and 4 were bonded at start, 1 h, 24 h, and 1 week after bleaching. A universal testing machine measured the SBS of the samples 24 h after bonding. After bracket debonding, the amount of residual adhesive on the enamel surface was observed under a stereomicroscope to determine the adhesive remnant index (ARI) scores. The SBS in the unbleached group was significantly higher than that in the bleached groups bonded immediately and 1 h after laser-assisted bleaching (P < 0.05). In groups 3 and 4 at start and group 2 at start and 1 h after laser-assisted bleaching, the SBS was found to be significantly lower than that in the control group. Significant differences in the ARI scores existed among groups as well. The SBS of brackets seems to increase quickly within an hour after laser-assisted bleaching and 24 h after conventional bleaching. Thus, this protocol can be recommended if it is necessary to bond the brackets on the same day of bleaching.

Effect of Er,Cr:YSGG laser irradiation on bovine enamel surface during in-office tooth bleaching ex vivo.

PubMed

Dionysopoulos, Dimitrios; Strakas, Dimitrios; Koliniotou-Koumpia, Eugenia; Koumpia, Effimia

2017-07-01

The aim of this in vitro study was to evaluate the effect of using Er,Cr:YSGG laser during in-office tooth bleaching on bovine enamel surface to evaluate the safety of this therapy on tooth tissues. Thirty-six enamel specimens were prepared from bovine incisors and divided into three groups: Group 1 specimens (control) received no bleaching treatment; Group 2 received a conventional in-office bleaching treatment (40 % H 2 O 2 ); Group 3 received laser-assisted bleaching procedure (40 % H 2 O 2 ) utilizing an Er,Cr:YSGG laser. The specimens were stored for 10 days after the bleaching treatment in artificial saliva. Vickers hardness was determined using a microhardness tester, and measurements for surface roughness were done using a VSI microscope. Three specimens for each experimental group were examined under SEM and mineral composition of the specimens was evaluated using EDS. Data were statistically analyzed using one-way ANOVA, Tukey's post hoc, Wilcoxon signed rank and Kruskal-Wallis tests (a = 0.05). The Vickers hardness of the enamel was reduced after in-office bleaching procedures (p < 0.05), and changes in surface morphology of the enamel were observed. However, the surface roughness of the enamel was not influenced (p > 0.05), and no changes in mineral composition of the enamel were detected after in-office bleaching procedures (p > 0.05). The laser-assisted bleaching treatment with Er,Cr:YSGG laser did not influence the enamel surface compared to the conventional bleaching technique. The safety of the use of Er,Cr:YSGG laser during in-office tooth bleaching regarding the surface properties of the enamel was confirmed under in vitro conditions.

Short-Term Coral Bleaching Is Not Recorded by Skeletal Boron Isotopes

PubMed Central

Schoepf, Verena; McCulloch, Malcolm T.; Warner, Mark E.; Levas, Stephen J.; Matsui, Yohei; Aschaffenburg, Matthew D.; Grottoli, Andréa G.

2014-01-01

Coral skeletal boron isotopes have been established as a proxy for seawater pH, yet it remains unclear if and how this proxy is affected by seawater temperature. Specifically, it has never been directly tested whether coral bleaching caused by high water temperatures influences coral boron isotopes. Here we report the results from a controlled bleaching experiment conducted on the Caribbean corals Porites divaricata, Porites astreoides, and Orbicella faveolata. Stable boron (δ11B), carbon (δ13C), oxygen (δ18O) isotopes, Sr/Ca, Mg/Ca, U/Ca, and Ba/Ca ratios, as well as chlorophyll a concentrations and calcification rates were measured on coral skeletal material corresponding to the period during and immediately after the elevated temperature treatment and again after 6 weeks of recovery on the reef. We show that under these conditions, coral bleaching did not affect the boron isotopic signature in any coral species tested, despite significant changes in coral physiology. This contradicts published findings from coral cores, where significant decreases in boron isotopes were interpreted as corresponding to times of known mass bleaching events. In contrast, δ13C and δ18O exhibited major enrichment corresponding to decreases in calcification rates associated with bleaching. Sr/Ca of bleached corals did not consistently record the 1.2°C difference in seawater temperature during the bleaching treatment, or alternatively show a consistent increase due to impaired photosynthesis and calcification. Mg/Ca, U/Ca, and Ba/Ca were affected by coral bleaching in some of the coral species, but the observed patterns could not be satisfactorily explained by temperature dependence or changes in coral physiology. This demonstrates that coral boron isotopes do not record short-term bleaching events, and therefore cannot be used as a proxy for past bleaching events. The robustness of coral boron isotopes to changes in coral physiology, however, suggests that reconstruction of seawater pH using boron isotopes should be uncompromised by short-term bleaching events. PMID:25396422

Short-term coral bleaching is not recorded by skeletal boron isotopes.

PubMed

Schoepf, Verena; McCulloch, Malcolm T; Warner, Mark E; Levas, Stephen J; Matsui, Yohei; Aschaffenburg, Matthew D; Grottoli, Andréa G

2014-01-01

Coral skeletal boron isotopes have been established as a proxy for seawater pH, yet it remains unclear if and how this proxy is affected by seawater temperature. Specifically, it has never been directly tested whether coral bleaching caused by high water temperatures influences coral boron isotopes. Here we report the results from a controlled bleaching experiment conducted on the Caribbean corals Porites divaricata, Porites astreoides, and Orbicella faveolata. Stable boron (δ11B), carbon (δ13C), oxygen (δ18O) isotopes, Sr/Ca, Mg/Ca, U/Ca, and Ba/Ca ratios, as well as chlorophyll a concentrations and calcification rates were measured on coral skeletal material corresponding to the period during and immediately after the elevated temperature treatment and again after 6 weeks of recovery on the reef. We show that under these conditions, coral bleaching did not affect the boron isotopic signature in any coral species tested, despite significant changes in coral physiology. This contradicts published findings from coral cores, where significant decreases in boron isotopes were interpreted as corresponding to times of known mass bleaching events. In contrast, δ13C and δ18O exhibited major enrichment corresponding to decreases in calcification rates associated with bleaching. Sr/Ca of bleached corals did not consistently record the 1.2°C difference in seawater temperature during the bleaching treatment, or alternatively show a consistent increase due to impaired photosynthesis and calcification. Mg/Ca, U/Ca, and Ba/Ca were affected by coral bleaching in some of the coral species, but the observed patterns could not be satisfactorily explained by temperature dependence or changes in coral physiology. This demonstrates that coral boron isotopes do not record short-term bleaching events, and therefore cannot be used as a proxy for past bleaching events. The robustness of coral boron isotopes to changes in coral physiology, however, suggests that reconstruction of seawater pH using boron isotopes should be uncompromised by short-term bleaching events.

Evaluation of several clinical parameters after bleaching with hydrogen peroxide at different concentrations: A randomized clinical trial.

PubMed

Lima, Suellen Nogueira Linares; Ribeiro, Izabella Santos; Grisotto, Marcos Augusto; Fernandes, Elizabeth Soares; Hass, Viviane; de Jesus Tavarez, Rudys Rodolfo; Pinto, Shelon Cristina Souza; Lima, Darlon Martins; Loguercio, Alessandro D; Bandeca, Matheus Coelho

2018-01-01

This randomized double-blind clinical trial compared tooth sensitivity (TS), bleaching efficacy, and cytokine levels after applying in-office bleaching treatments containing 15% and 35% hydrogen peroxide (HP15% and HP35%, respectively). Twenty-five volunteers were randomly assigned to receive HP15% or HP35% treatment. The bleaching agent was applied in three 15-min applications per session. Two bleaching sessions were separated by a 1-week interval. The participants scored TS using a visual analog scale and numerical rating scale. Bleaching efficacy was determined by subjective and objective methods. Gingival crevicular fluid was collected from three jaws sites per patient for the analysis of fluid volume. Flow cytometry was used to analyze gingival crevicular fluid levels of interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-10, tumor necrosis factor, and interferon-gamma. All measurements were obtained before and after bleaching. All data were statistically analyzed (α=0.05). The absolute risk and intensity of TS was higher for HP35% than for HP15% (p>0.002). One month post-bleaching, HP35% produced more bleaching than HP15% (p=0.02). However patient perception (p=0.06) and patient satisfaction (p=0.53) with regard to bleaching were not significantly different. No significant differences existed in the gingival fluid volume (p>0.38) or in any cytokine level (p>0.05) for either HP concentration. Treatment: with HP35% is more effective than HP15%, but generates a greater risk and intensity of TS. No inflammatory changes occurred despite the difference in the HP concentrations. Hydrogen peroxide at a lower concentration (e.g., 15%) should be considered a good treatment alternative for in-office bleaching because the higher concentration for in-office bleaching generates a greater risk and intensity of TS for patients. Copyright © 2017 Elsevier Ltd. All rights reserved.

The efficacy of laser-assisted in-office bleaching and home bleaching on sound and demineralized enamel

PubMed Central

Akbari, Majid; Mohammadpour, Sakineh

2015-01-01

Aims: This study investigated the effectiveness of laser-assisted in-office bleaching and home-bleaching in sound and demineralized enamel. Materials and Methods: The sample consisted of 120 freshly-extracted bovine incisors. Half of the specimens were stored in a demineralizing solution to induce white spot lesions. Following exposure to a tea solution for 7.5 days, the specimens were randomly assigned to 4 groups of 30 according to the type of enamel and the bleaching procedure employed. Groups 1 and 2 consisted of demineralized teeth subjected to in-office bleaching and home bleaching, whereas in groups 3 and 4, sound teeth were subjected to in-office and home bleaching, respectively. A diode laser (810 nm, 2 W, continuous wave, four times for 15 seconds each) was employed for assisting the in-office process. The color of the specimens was measured before (T1) and after (T2) staining and during (T3) and after (T4) the bleaching procedures using a spectrophotometer. The color change (ΔE) between different treatments stages was compared among the groups. Results: There were significant differences in the color change between T2 and T3 (ΔE T2–T3) and T2 and T4 (ΔE T2–T4) stages among the study groups (p<0.05). Pairwise comparison by Duncan test revealed that both ΔET2–T3 and ΔET2–T4 were significantly greater in demineralized teeth submitted to laser-assisted in-office bleaching (group 1) as compared to the other groups (P< 0.05). Conclusion: Laser-assisted in-office bleaching could provide faster and greater whitening effect than home bleaching on stained demineralized enamel, but both procedures produced comparable results on sound teeth. PMID:26877590

Nanotribological and Nanomechanical Properties Changes of Tooth After Bleaching and Remineralization in Wet Environment.

PubMed

Yu, Dandan; Gao, Shanshan; Min, Jie; Zhang, Qianqian; Gao, Shuai; Yu, Haiyang

2015-12-01

Teeth bleaching cases had increased with people's desire for oral aesthetic; however, bleached teeth would still undertake chewing actions and remineralizing process in saliva. Nanotribological and nanomechanical properties are proper displays for dental performance of bleached teeth. The purpose of the research was to reveal the effect of bleaching and remineralization on the nanotribological and nanomechanical properties of teeth in wet environment. The specimens were divided into four groups according to the bleaching products used: 12 % hydrogen peroxide (HP) (12HP group); 15 % carbamide peroxide (CP) (15CP group); 35 % CP (35CP group); and artificial saliva (control group). The nanotribological and nanomechanical property changes of tooth enamel after bleaching and remineralization were evaluated respectively by nanoscratch and nanoindentation tests in wet environment, imitating the wet oral environment. The morphology changes were evaluated by statistical parametric mapping (SPM) and scanning electron microscopy (SEM). After bleaching, 12HP group and 15CP group showed increased scratch depth with more pile ups on the scratch edges, decreased nanohardness, and corroded surface appearance. While the 35CP group showed an increase in nanoscratch depth, no change in nanohardness and surface appearance was observed. The control group showed no change in these measurements. After remineralization, the three bleaching groups showed decreased nanoscratch depth and no change of nanohardness compared with the bleached teeth. And the control group showed no changes in nanotribological and nanomechanical properties. The nanotribological and nanomechanical properties of the 12HP group and 15CP group were affected by bleaching, but the nanotribological properties recovered partly and the nanomechanical properties got no change after 1 week of remineralization. As for the 35CP group, the nanotribological properties were influenced and the nanomechanical properties were not affected. These results remind us of taking actions to protect our teeth during bleaching.

Nanotribological and Nanomechanical Properties Changes of Tooth After Bleaching and Remineralization in Wet Environment

NASA Astrophysics Data System (ADS)

Yu, Dandan; Gao, Shanshan; Min, Jie; Zhang, Qianqian; Gao, Shuai; Yu, Haiyang

2015-12-01

Teeth bleaching cases had increased with people's desire for oral aesthetic; however, bleached teeth would still undertake chewing actions and remineralizing process in saliva. Nanotribological and nanomechanical properties are proper displays for dental performance of bleached teeth. The purpose of the research was to reveal the effect of bleaching and remineralization on the nanotribological and nanomechanical properties of teeth in wet environment. The specimens were divided into four groups according to the bleaching products used: 12 % hydrogen peroxide (HP) (12HP group); 15 % carbamide peroxide (CP) (15CP group); 35 % CP (35CP group); and artificial saliva (control group). The nanotribological and nanomechanical property changes of tooth enamel after bleaching and remineralization were evaluated respectively by nanoscratch and nanoindentation tests in wet environment, imitating the wet oral environment. The morphology changes were evaluated by statistical parametric mapping (SPM) and scanning electron microscopy (SEM). After bleaching, 12HP group and 15CP group showed increased scratch depth with more pile ups on the scratch edges, decreased nanohardness, and corroded surface appearance. While the 35CP group showed an increase in nanoscratch depth, no change in nanohardness and surface appearance was observed. The control group showed no change in these measurements. After remineralization, the three bleaching groups showed decreased nanoscratch depth and no change of nanohardness compared with the bleached teeth. And the control group showed no changes in nanotribological and nanomechanical properties. The nanotribological and nanomechanical properties of the 12HP group and 15CP group were affected by bleaching, but the nanotribological properties recovered partly and the nanomechanical properties got no change after 1 week of remineralization. As for the 35CP group, the nanotribological properties were influenced and the nanomechanical properties were not affected. These results remind us of taking actions to protect our teeth during bleaching.

Effects of varying concentrations of bleach on in vitro HIV-1 replication and the relevance to injection drug use.

PubMed

Contoreggi, C; Jones, S; Simpson, P; Lange, W R; Meyer, W A

2000-01-01

The use of bleach (hypochlorite) as a disinfectant for drug injection equipment in the intravenous-drug-using population was recommended early in the HIV-1/AIDS epidemic. Epidemiological studies have challenged the use of bleach as an effective measure to prevent HIV-1 transmission. However, in vitro HIV-1 coculture studies have shown that a high concentration of bleach is an effective cytotoxic and potentially virucidal agent. In this study, we demonstrate that HIV-1 peripheral blood mononuclear cell cocultures containing low concentrations of hypochlorite in the media showed earlier conversion to HIV-1 positivity, as measured by the presence of p24 antigen. HIV-1 cocultures with high concentrations of hypochlorite in the culture media, which appeared to be highly cytotoxic, and HIV-1 cocultures without bleach in the media did not exhibit this early p24 antigen positivity. Hypochlorite chemically disinfects by releasing free chlorine that is a potent oxidant. In injection drug equipment, a low residual concentration of bleach is likely to remain in cleaned equipment despite rinsing with water. Low concentrations of oxidants have been shown to enhance tissue inflammation, in vivo, as well as HIV-1 replication in vitro. Previous studies have shown that despite vigorous cleaning of blood-contaminated injection syringes with bleach followed by water, microaggregates of residual blood remained in bleach-cleaned blood-contaminated syringes. Hypothetically, oxidant effects of the residual bleach in the bleach-cleaned syringes could enhance the possibility of infection by remaining HIV-1 contained in a contaminated syringe. We suggest that the likelihood of an injection drug user contracting HIV-1 through the sharing of a bleach-cleaned blood-contaminated syringe may be increased by the cotransmission of residual bleach and its localized tissue-inflammatory effects; however, this has not been statistically proven in epidemiological studies. Copyright 2000 S. Karger AG, Basel.

Sensory and Functionality Differences of Whey Protein Isolate Bleached by Hydrogen or Benzoyl Peroxide.

PubMed

Smith, Tucker J; Foegeding, E Allen; Drake, MaryAnne

2015-10-01

Whey protein is a highly functional food ingredient used in a wide variety of applications. A large portion of fluid whey produced in the United States is derived from Cheddar cheese manufacture and contains annatto (norbixin), and therefore must be bleached. The objective of this study was to compare sensory and functionality differences between whey protein isolate (WPI) bleached by benzoyl peroxide (BP) or hydrogen peroxide (HP). HP and BP bleached WPI and unbleached controls were manufactured in triplicate. Descriptive sensory analysis and gas chromatography-mass spectrometry were conducted to determine flavor differences between treatments. Functionality differences were evaluated by measurement of foam stability, protein solubility, SDS-PAGE, and effect of NaCl concentration on gelation relative to an unbleached control. HP bleached WPI had higher concentrations of lipid oxidation and sulfur containing volatile compounds than both BP and unbleached WPI (P < 0.05). HP bleached WPI was characterized by high aroma intensity, cardboard, cabbage, and fatty flavors, while BP bleached WPI was differentiated by low bitter taste. Overrun and yield stress were not different among WPI (P < 0.05). Soluble protein loss at pH 4.6 of WPI decreased by bleaching with either hydrogen peroxide or benzoyl peroxide (P < 0.05), and the heat stability of WPI was also distinct among WPI (P < 0.05). SDS PAGE results suggested that bleaching of whey with either BP or HP resulted in protein degradation, which likely contributed to functionality differences. These results demonstrate that bleaching has flavor effects as well as effects on many of the functionality characteristics of whey proteins. Whey protein isolate (WPI) is often used for its functional properties, but the effect of oxidative bleaching chemicals on the functional properties of WPI is not known. This study identifies the effects of hydrogen peroxide and benzoyl peroxide on functional and flavor characteristics of WPI bleached by hydrogen and benzoyl peroxide and provides insights for the product applications which may benefit from bleaching. © 2015 Institute of Food Technologists®

Efficacy and cytotoxicity of a bleaching gel after short application times on dental enamel.

PubMed

Soares, Diana Gabriela; Ribeiro, Ana Paula Dias; da Silveira Vargas, Fernanda; Hebling, Josimeri; de Souza Costa, Carlos Alberto

2013-11-01

This study aimed to evaluate and correlate the efficacy and cytotoxicity of a 35 % hydrogen peroxide (HP) bleaching gel after different application times on dental enamel. Enamel/dentin disks in artificial pulp chambers were placed in wells containing culture medium. The following groups were formed: G1, control (no bleaching); G2 and G3, three or one 15-min bleaching applications, respectively; and G4 and G5, three or one 5-min bleaching applications, respectively. Extracts (culture medium with bleaching gel components) were applied for 60 min on cultured odontoblast-like MDPC-23 cells. Cell metabolism (methyl tetrazolium assay) (Kruskal-Wallis/Mann-Whitney; α = 5 %) and cell morphology (scanning electron microscopy) were analyzed immediately after the bleaching procedures and the trans-enamel and trans-dentinal HP diffusion quantified (one-way analysis of variance/Tukey's test; α = 5 %). The alkaline phosphatase (ALP) activity was evaluated 24 h after the contact time of the extracts with the cells (Kruskal-Wallis/Mann-Whitney; α = 5 %). Tooth color was analyzed before and 24 h after bleaching using a spectrophotometer according to the Commission Internationale de l'Eclairage L*a*b* system (Kruskal-Wallis/Mann-Whitney; α = 0.05). Significant difference (p < 0.05) in cell metabolism occurred only between G1 (control, 100 %) and G2 (60.6 %). A significant decrease (p < 0.05) in ALP activity was observed between G2, G3, and G4 in comparison with G1. Alterations on cell morphology were observed in all bleached groups. The highest values of HP diffusion and color alterations were observed for G2, with significant difference among all experimental groups (p < 0.05). G3 and G4 presented intermediate color change and HP diffusion values with no statistically significant differences between them (p > 0.05). The lowest amount of HP diffusion was observed in G5 (p < 0.05), which also exhibited no significant color alteration compared to the control group (p > 0.05). HP diffusion through dental tissues and its cytotoxic effects were proportional to the contact time of the bleaching gel with enamel. However, shorter bleaching times reduced bleaching efficacy. Shortening the in-office tooth bleaching time could be an alternative to minimize the cytotoxic effects of this clinical procedure to pulp tissue. However, the reduced time of bleaching agent application on enamel may not provide adequate esthetic outcome.

Effect of light-enhanced bleaching on in vitro surface and intrapulpal temperature rise.

PubMed

Baik, J W; Rueggeberg, F A; Liewehr, F R

2001-01-01

This study investigated the effect of the presence, absence, and aging of a heat-enhancing compound (colorant) added to bleaching gel on the temperature rise of the gel itself, as well as the temperature rise within the pulp chamber, when a tooth was exposed to a variety of light-curing units in vitro. An extracted human upper central incisor was fitted with thermocouples placed in the pulp chamber as well as on the facial tooth surface. A temperature-controlled simulated intrapulpal fluid flow was provided to the tooth, and bleaching agent (Opalesence XTRA, Ultradent) containing heat-enhancing colorant, aged colorant, or no colorant was applied to the facial surface. The tooth and light-curing unit were placed in a thermostatically controlled oven at 37 degrees C, and real-time gel and intrapulpal temperature values were recorded digitally. Light-curing units used were a plasma arc light (PAC) (PowerPac, ADT), a conventional quartz tungsten halogen source (QTH) (Optilux 501, Demetron/Kerr), the QTH light used in high-power (bleaching) mode, and an argon ion laser (AccuCure 3000, LaserMed). An exposure scenario simulating light-enhanced bleaching of 10 upper teeth was developed. Temperature rise over the pre-exposure, baseline value associated with the last light exposure in the bleaching sequence was calculated for each curing and bleaching combination. Five replications for each test condition were made. Temperature rise values were compared using analysis of variance (ANOVA) at a preset alpha of 0.05. When fresh colorant-containing bleach was used, the PAC light increased bleach temperature 39.3 degrees C above baseline. With no added colorant, temperature rise was 37.1 degrees C. The QTH light in bleach mode resulted in gel temperature 24.8 degrees C above baseline, whereas the temperature increase was only 11.5 degrees C when no colorant was used. Conventional QTH light use increased fresh bleach temperature by 17.7 degrees C, whereas an increase of only 11.1 degrees C was measured without colorant. The argon ion laser produced equivalent temperature rise regardless of the presence or freshness of the colorant, approximately 9.4 degrees C. Intrapulpal temperatures were all significantly lower than those recorded in the bleaching gel and ranged from 5 degrees to 8 degrees C. As a rule, the presence of fresh heat-enhancing colorant in the bleaching gel resulted in a significant intrapulpal temperature increase (approximately 1 degrees C) over that reached using other lights. The PAC and the QTH light used in bleach mode induced greater intrapulpal temperature rise than the laser. Freshness of bleaching agent incorporating light-activated, heat-enhancing colorant influences temperature rise of bleaching gel and also may increase intrapulpal temperature values. Use of intense lights does elevate bleach temperature and also results in increased intrapulpal temperature that may further impact on patient sensitivity and pulpal health resulting from this treatment.

Influence of Bleaching on Flavor of 34% Whey Protein Concentrate and Residual Benzoic Acid Concentration in Dried Whey Proteins

USDA-ARS?s Scientific Manuscript database

Previous studies have shown that bleaching negatively affects the flavor of 70% whey protein concentrate (WPC70), but bleaching effects on lower-protein products have not been established. Benzoyl peroxide (BP), a whey bleaching agent, degrades to benzoic acid (BA) and may elevate BA concentrations...

Influence of bleaching on flavor of 34% whey protein concentrate and residual benzoic acid concentration in dried whey products

USDA-ARS?s Scientific Manuscript database

Previous studies have shown that bleaching negatively affects the flavor of 70% whey protein concentrate (WPC70), but bleaching effects on lower-protein products have not been established. Benzoyl peroxide (BP), a whey bleaching agent, degrades to benzoic acid (BA) and may elevate BA concentrations...

OSL response bleaching of BeO samples, using fluorescent light and blue LEDs

NASA Astrophysics Data System (ADS)

Groppo, D. P.; Caldas, L. V. E.

2016-07-01

The optically stimulated luminescence (OSL) is widely used as a dosimetric technique for many applications. In this work, the OSL response bleaching of BeO samples was studied. The samples were irradiated using a beta radiation source (90Sr+90Y); the bleaching treatments (fluorescent light and blue LEDs) were performed, and the results were compared. Various optical treatment time intervals were tested until reaching the complete bleaching of the OSL response. The best combination of the time interval and bleaching type was analyzed.

Effect of Two-minute Application of 35% Sodium Ascorbate on Composite Bond Strength following Bleaching.

PubMed

Ismail, Eman H; Kilinc, Evren; Hardigan, Patrick C; Rothrock, James K; Thompson, Jeffrey Y; Garcia-Godoy, Cristina

2017-10-01

The aim of this study is to assess the effect of 35% sodium ascorbate on microtensile bond strength of dentin immediately after bleaching with 35% hydrogen peroxide. A total of 25 sound human 3 rd molars were collected. Teeth were randomly divided into five groups for different treatments: Group I [bleaching + immediate bonding (i.e., restoration)], group II (bleaching + delayed bonding), group III (bleaching + sodium ascorbate + immediate bonding), group IV (bleaching + sodium ascorbate + delayed bonding), and group V (bonding only). After bleaching, but before bonding, groups II and IV were stored for 1 week in deionized water at 37°C. All samples were bonded using OptiBoned FL (Kerr) and Filtek Supreme (3M/ESPE). Teeth were sectioned into 1 × 1 mm 2 bars, and microtensile bond strength was tested with a universal testing machine (Instron 8841) at a cross-head speed of 0.5 mm/minute. Microtensile bond strength differed significantly across the five groups, with a significant reduction in microtensile bond strength observed for samples in group I relative to samples in any of the other treatment groups (p < 0.05). The application of a high concentration of sodium ascorbate for a shorter time reversed the negative effect of 35% hydrogen peroxide bleaching on composite bonding strength to dentin. The negative effects of bleaching on composite bonding can be neutralized by the application of the reversing agent sodium ascorbate thus, increasing the efficiency of clinic chair time. This is clinically relevant for those patients requiring restorative treatment immediately after in-office bleaching.

Effect of Laser-assisted and Conventional In-office Bleaching on Monomer Release from Microhybrid and Nanohybrid Composite.

PubMed

Omrani, Ladan Ranjbar; Farjadfar, Shayan; Pedram, Parham; Sadray, Sima; Kamangar, Sedighe Sadat Hashemi; Chiniforoush, Nasim

2017-06-30

Bleaching might affect structural properties of composite materials, and lead to monomer release. This study aimed to evaluate the effect of Laser-assisted and conventional in-office bleaching on the release of BIS-GMA, TEGDMA, and UDMA monomers from a nanohybrid and a microhybrid BIS-GMA based composite. 32 samples of each composite, were divided into 4 subgroups; subgroup 1: Conventional in-office bleaching (CIB) with the Opalescence Boost PF 38% gel, subgroup 2: Laser-assisted bleaching (LBO) with the Opalescence Boost PF 38% gel, subgroup 3: Laser-assisted bleaching (LBH) with the JW Power bleaching gel, subgroup 4: (CO) control without bleaching. All the samples were immersed in tubes of 2cc Ethanol 75% medium. The released monomers were analyzed using the high performance liquid chromatography (HPLC) method 24 h, 7, and 28 days. Data's were analyzed by Univariate Analysis of Variance test followed by Tukeys HSD. The amount of TEGDMA monomer released was not significant. However, nanohybrid composites showed significantly more monomer release than microhybrid composites (P < 0.05). For UDMA the interaction was significant only after 1 week. In microhybrid composites, the CO subgroup showed more monomer release than LBH and LBO. In nanohybrid composites, LBH showed more monomer release than CIB and CO subgroups. For BIS-GMA monomers the interaction was significant at all time periods and the LBH subgroup of nanohybrid composite had significantly more BIS_GMA release in comparison to other subgroups. Bleaching by laser with JW Power Bleaching gel led to more monomer release in nanohybrid composite.

Effect of high- or low-concentration bleaching agents containing calcium and/or fluoride on enamel microhardness.

PubMed

Furlan, Isabella Spinardi; Bridi, Enrico Coser; Amaral, Flávia Lucisano Botelho do; França, Fabiana Mantovani Gomes; Turssi, Cecilia Pedroso; Basting, Roberta Tarkany

2017-01-01

The aim of this in vitro study was to evaluate enamel microhardness following bleaching treatments using either high- or low-concentration hydrogen peroxide (HP) agents containing calcium and/or fluoride. Sixty enamel blocks were bleached with 1 of 6 different bleaching agents (n = 10). The high-concentration HP agents were Whiteness HP Maxx (35% HP), Whiteness HP Blue (35% HP, 2% calcium gluconate), Pola Office+ (37.5% HP, 5% potassium nitrate), and Opalescence Boost (38% HP, 1.1% fluoride ion, 3% potassium nitrate). The low-concentration HP agents evaluated were Pola Day (9.5% HP) and White Class (10% HP, potassium nitrate, calcium, fluoride). High-concentration agents were applied in 3 sessions, whereas low-concentration agents were applied for 14 days. Knoop microhardness measurements were taken on the surface of the enamel before bleaching, at various timepoints during bleaching, and 14 days after the final bleaching treatment. The 2-way analysis of variance test showed that microhardness values were significantly influenced by the bleaching agent (P < 0.001) and application time (P < 0.001). The Tukey test showed that enamel bleached with Whiteness HP Maxx or White Class presented lower microhardness values than did the enamel treated with the remaining products. There was a reduction in micro-hardness values up to the end of the treatment. The results showed that the composition, concentration, and application protocol for each bleaching agent influenced the enamel microhardness values in that the microhardness decreased over time, regardless of the agent used or the addition of calcium and/or fluoride.

A primary estimation of PCDD/Fs release reduction from non-wood pulp and paper industry in China based on the investigation of pulp bleaching with chlorine converting to chlorine dioxide.

PubMed

Xiao, Qingcong; Song, Xiaoqian; Li, Wenchao; Zhang, Yuanna; Wang, Hongchen

2017-10-01

Chlorine bleaching technology (C process, CEH process, H process and theirs combination), which was identified as a primary formation source of PCDD/Fs, is still widely used by the vast majority of Chinese non-wood pulp and paper mills (non-wood PMs). The purpose of this study was to provide information and data support for further eliminating dioxin for non-wood PMs in China, and especially to evaluate the PCDD/Fs release reduction for those mills converting their pulp bleaching processes from CEH to ECF. The PCDD/Fs concentrations of the bleached pulp and bleaching wastewater with ECF bleaching were in the ranges of 0.13-0.8 ng TEQ kg -1 , and 0.15-1.9 pg TEQ L -1 , respectively, which were far lower than those with CEH process, indicating that the ECF process is an effective alternative bleaching technology to replace CEH in Chinese non-wood PMs to reduce dioxin release. The release factor via flue gas of the alkali recovery boiler in Chinese non-wood PMs was first reported to be 0.092 μg TEQ Ad t -1 in this study. On the assumption that pulp bleaching processes of all Chinese non-wood PMs were converted from CEH to ECF, the annual release of PCDD/Fs via the bleaching wastewater and bleached pulp would be reduced by 79.1%, with a total of 1.60 g TEQ. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inflammatory response of human dental pulp to at-home and in-office tooth bleaching

PubMed Central

Vaz, Maysa Magalhães; Lopes, Lawrence Gonzaga; Cardoso, Paula Carvalho; de Souza, João Batista; Batista, Aline Carvalho; Costa, Nádia Lago; Torres, Érica Miranda; Estrela, Carlos

2016-01-01

ABSTRACT Tooth bleaching is a technique of choice to obtain a harmonious smile, but bleaching agents may damage the dental pulp. Objective: This study evaluated the inflammatory responses of human dental pulp after the use of two bleaching techniques. Material and Methods: Pulp samples were collected from human third molars extracted for orthodontic reasons and divided into three groups: control - no tooth bleaching (CG) (n=7); at-home bleaching with 15% carbamide peroxide (AH) (n = 10), and in-office bleaching with 38% hydrogen peroxide (IO) (n=12). Pulps were removed and stained with hematoxylin-eosin for microscopic analysis of inflammation intensity, collagen degradation, and pulp tissue organization. Immunohistochemistry was used to detect mast cells (tryptase+), blood vessels (CD31+), and macrophages (CD68+). Chi-square, Kruskal-Wallis, and Mann Whitney tests were used for statistical analysis. The level of significance was set at p<.05. Results: The inflammation intensity and the number of macrophages were significantly greater in IO than in AH and CG (p<0.05). The results of CD31+ (blood vessels per mm2) were similar in CG (61.39±20.03), AH (52.29±27.62), and IO (57.43±8.69) groups (p>0.05). No mast cells were found in the pulp samples analyzed. Conclusion: In-office bleaching with 38% hydrogen peroxide resulted in more intense inflammation, higher macrophages migration, and greater pulp damage then at-home bleaching with 15% carbamide peroxide, however, these bleaching techniques did not induce migration of mast cells and increased the number of blood vessels. PMID:27812622

Caribbean Corals in Crisis: Record Thermal Stress, Bleaching, and Mortality in 2005

PubMed Central

Eakin, C. Mark; Morgan, Jessica A.; Heron, Scott F.; Smith, Tyler B.; Liu, Gang; Alvarez-Filip, Lorenzo; Baca, Bart; Bartels, Erich; Bastidas, Carolina; Bouchon, Claude; Brandt, Marilyn; Bruckner, Andrew W.; Bunkley-Williams, Lucy; Cameron, Andrew; Causey, Billy D.; Chiappone, Mark; Christensen, Tyler R. L.; Crabbe, M. James C; Day, Owen; de la Guardia, Elena; Díaz-Pulido, Guillermo; DiResta, Daniel; Gil-Agudelo, Diego L.; Gilliam, David S.; Ginsburg, Robert N.; Gore, Shannon; Guzmán, Héctor M.; Hendee, James C.; Hernández-Delgado, Edwin A.; Husain, Ellen; Jeffrey, Christopher F. G.; Jones, Ross J.; Jordán-Dahlgren, Eric; Kaufman, Les S.; Kline, David I.; Kramer, Philip A.; Lang, Judith C.; Lirman, Diego; Mallela, Jennie; Manfrino, Carrie; Maréchal, Jean-Philippe; Marks, Ken; Mihaly, Jennifer; Miller, W. Jeff; Mueller, Erich M.; Muller, Erinn M.; Orozco Toro, Carlos A.; Oxenford, Hazel A.; Ponce-Taylor, Daniel; Quinn, Norman; Ritchie, Kim B.; Rodríguez, Sebastián; Ramírez, Alberto Rodríguez; Romano, Sandra; Samhouri, Jameal F.; Sánchez, Juan A.; Schmahl, George P.; Shank, Burton V.; Skirving, William J.; Steiner, Sascha C. C.; Villamizar, Estrella; Walsh, Sheila M.; Walter, Cory; Weil, Ernesto; Williams, Ernest H.; Roberson, Kimberly Woody; Yusuf, Yusri

2010-01-01

Background The rising temperature of the world's oceans has become a major threat to coral reefs globally as the severity and frequency of mass coral bleaching and mortality events increase. In 2005, high ocean temperatures in the tropical Atlantic and Caribbean resulted in the most severe bleaching event ever recorded in the basin. Methodology/Principal Findings Satellite-based tools provided warnings for coral reef managers and scientists, guiding both the timing and location of researchers' field observations as anomalously warm conditions developed and spread across the greater Caribbean region from June to October 2005. Field surveys of bleaching and mortality exceeded prior efforts in detail and extent, and provided a new standard for documenting the effects of bleaching and for testing nowcast and forecast products. Collaborators from 22 countries undertook the most comprehensive documentation of basin-scale bleaching to date and found that over 80% of corals bleached and over 40% died at many sites. The most severe bleaching coincided with waters nearest a western Atlantic warm pool that was centered off the northern end of the Lesser Antilles. Conclusions/Significance Thermal stress during the 2005 event exceeded any observed from the Caribbean in the prior 20 years, and regionally-averaged temperatures were the warmest in over 150 years. Comparison of satellite data against field surveys demonstrated a significant predictive relationship between accumulated heat stress (measured using NOAA Coral Reef Watch's Degree Heating Weeks) and bleaching intensity. This severe, widespread bleaching and mortality will undoubtedly have long-term consequences for reef ecosystems and suggests a troubled future for tropical marine ecosystems under a warming climate. PMID:21125021

Improved pulp bleaching potential of Bacillus subtilis WB800 through overexpression of three lignolytic enzymes from various bacteria.

PubMed

Ozer, Aysegul; Uzuner, Ugur; Guler, Halil Ibrahim; Ay Sal, Fulya; Belduz, Ali Osman; Deniz, Ilhan; Canakci, Sabriye

2017-12-29

A chemical bleaching process of paper pulps gives off excessive amount of chlorinated organic wastes mostly released to environment without exposing complete bioremediaton. Recent alternative and eco-friendly approaches toward pulp bleaching appear more responsive to environmental awareness. Here we report, direct use of a recombinant Bacillus subtilis bacterium for pulp bleaching, endowed with three ligninolytic enzymes from various bacteria. In addition, efficient bleaching performance from glutathione-S-transferase (GST) biocatalyst tested for the first time in pulp bleaching applications was also achieved. Simultaneous and extracellular overproduction of highly active GST, laccase, and lignin peroxidase catalysts were also performed by Bacillus cells. Both enhanced bleaching success and improved delignification rates were identified when enzyme combinations tested on both pine kraft and waste paper pulps, ranging from 69.75% to 79.18% and 60.89% to 74.65%, respectively. Furthermore, when triple enzyme combination applied onto the papers from pine kraft and waste pulps, the best ISO brightness values were identified as 66.45% and 64.67%, respectively. The delignification rates of pulp fibers exposed to various enzymatic bleaching sequences were comparatively examined under SEM. In conclusion, the current study points out that in near future, a more fined-tuned engineering of pulp-colonizing bacteria may become a cost-effective and environmentally friendly alternative to chemical bleaching. © 2017 International Union of Biochemistry and Molecular Biology, Inc.

Graded changes in enamel component volumes resulted from a short tooth bleaching procedure.

PubMed

Ferreira, Artemisa Fernanda Moura; Perez, Flávia Maria de Moraes Ramos; Limeira Júnior, Francisco de Assis; de Moura, Mirella de Fátima Liberato; de Sousa, Frederico Barbosa

2016-05-01

To test the hypothesis that changes in enamel component volumes (mineral, organic, and water volumes, and permeability) are graded from outer to inner enamel after a short bleaching procedure. Extracted unerupted human third molars had half of their crowns bleached (single bleaching session, 3 × 15 min), and tooth shade changes in bleached parts were analyzed with a spectrophotometer. Ground sections were prepared, component volumes and permeability were quantified at histological points located at varying distances from the enamel surface (n=10 points/location), representing conditions before and after bleaching. Tooth shade changes were significant (p<0.001; 95% CI=-1/-8; power=99%), and most of the enamel layer was unaffected after bleaching, except at the outer layers. Multiple analysis of covariances revealed that most of the variance of the change in enamel composition after bleaching was explained by the combination of the set of types of component volume (in decreasing order of relevance: mineral loss, organic gain, water gain, and decrease in permeability) with the set of distances from the enamel surface (graded from the enamel surface inward) (canonical R(2)=0.97; p<0.0001; power>99%). Changes in enamel composition after a short bleaching procedure followed a gradient within component volumes (mineral loss>organic gain>water gain>decrease in permeability) and decreased from the enamel surface inward. Copyright © 2016 Elsevier Ltd. All rights reserved.

Compositional changes of human hair melanin resulting from bleach treatment investigated by nanoscale secondary ion mass spectrometry.

PubMed

Kojima, Toru; Yamada, Hiromi; Isobe, Mitsuru; Yamamoto, Toshihiko; Takeuchi, Miyuki; Aoki, Dan; Matsushita, Yasuyuki; Fukushima, Kazuhiko

2014-11-01

It is important to understand the influence of bleach treatment on human hair because it is one of the most important chemical treatments in hair cosmetic processes. A comparison of the elemental composition of melanin between virgin hair and bleached hair would provide important information about the structural changes of melanin. To investigate the elemental composition of melanin granules in virgin black hair and bleached hair, these hair cross-sections are analyzed by using a nanoscale secondary ion mass spectrometry (NanoSIMS). The virgin black hair and bleached hair samples were embedded in resin and smooth hair cross-sections were obtained using an ultramicrotome. NanoSIMS measurements were performed using a Cs(+) primary ion beam to detect negative secondary ions. More intensive (16) O(-) ions were detected from the melanin granules of bleached hair than from those of virgin black hair in NanoSIMS (16) O(-) ion image. In addition, it was indicated that (16) O(-) ion intensity and (16) O(-) /(12) C(14) N(-) ion intensity ratio of melanin granules in bleached hair were higher than those in virgin black hair. Nanoscale secondary ion mass spectrometry analysis of the cross-sections of virgin black hair and bleached hair indicated that the oxygen content in melanin granules was increased by bleach treatment. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Reef corals bleach to resist stress.

PubMed

Obura, David O

2009-02-01

A rationale is presented here for a primary role of bleaching in regulation of the coral-zooxanthellae symbiosis under conditions of stress. Corals and zooxanthellae have fundamentally different metabolic rates, requiring active homeostasis to limit zooxanthellae production and manage translocated products to maintain the symbiosis. The control processes for homeostasis are compromised by environmental stress, resulting in metabolic imbalance between the symbionts. For the coral-zooxanthella symbiosis the most direct way to minimize metabolic imbalance under stress is to reduce photosynthetic production by zooxanthellae. Two mechanisms have been demonstrated that do this: reduction of the chlorophyll concentration in individual zooxanthellae and reduction of the relative biomass of zooxanthellae. Both mechanisms result in visual whitening of the coral, termed bleaching. Arguments are presented here that bleaching provides the final control to minimize physiological damage from stress as an adversity response to metabolic imbalance. As such, bleaching meets the requirements of a stress response syndrome/general adaptive mechanism that is sensitive to internal states rather than external parameters. Variation in bleaching responses among holobionts reflects genotypic and phenotypic differentiation, allowing evolutionary change by natural selection. Thus, reef corals bleach to resist stress, and thereby have some capacity to adapt to and survive change. The extreme thermal anomalies causing mass coral bleaching worldwide lie outside the reaction norms for most coral-zooxanthellae holobionts, revealing the limitations of bleaching as a control mechanism.

Electrochromic window with high reflectivity modulation

DOEpatents

Goldner, Ronald B.; Gerouki, Alexandra; Liu, Te-Yang; Goldner, Mark A.; Haas, Terry E.

2000-01-01

A multi-layered, active, thin film, solid-state electrochromic device having a high reflectivity in the near infrared in a colored state, a high reflectivity and transmissivity modulation when switching between colored and bleached states, a low absorptivity in the near infrared, and fast switching times, and methods for its manufacture and switching are provided. In one embodiment, a multi-layered device comprising a first indium tin oxide transparent electronic conductor, a transparent ion blocking layer, a tungsten oxide electrochromic anode, a lithium ion conducting-electrically resistive electrolyte, a complimentary lithium mixed metal oxide electrochromic cathode, a transparent ohmic contact layer, a second indium oxide transparent electronic conductor, and a silicon nitride encapsulant is provided. Through elimination of optional intermediate layers, simplified device designs are provided as alternative embodiments. Typical colored-state reflectivity of the multi-layered device is greater than 50% in the near infrared, bleached-state reflectivity is less than 40% in the visible, bleached-state transmissivity is greater than 60% in the near infrared and greater than 40% in the visible, and spectral absorbance is less than 50% in the range from 0.65-2.5 .mu.m.

Excess algal symbionts increase the susceptibility of reef corals to bleaching

NASA Astrophysics Data System (ADS)

Cunning, Ross; Baker, Andrew C.

2013-03-01

Rising ocean temperatures associated with global climate change are causing mass coral bleaching and mortality worldwide. Understanding the genetic and environmental factors that mitigate coral bleaching susceptibility may aid local management efforts to help coral reefs survive climate change. Although bleaching susceptibility depends partly on the genetic identity of a coral's algal symbionts, the effect of symbiont density, and the factors controlling it, remain poorly understood. By applying a new metric of symbiont density to study the coral Pocillopora damicornis during seasonal warming and acute bleaching, we show that symbiont cell ratio density is a function of both symbiont type and environmental conditions, and that corals with high densities are more susceptible to bleaching. Higher vulnerability of corals with more symbionts establishes a quantitative mechanistic link between symbiont density and the molecular basis for coral bleaching, and indicates that high densities do not buffer corals from thermal stress, as has been previously suggested. These results indicate that environmental conditions that increase symbiont densities, such as nutrient pollution, will exacerbate climate-change-induced coral bleaching, providing a mechanistic explanation for why local management to reduce these stressors will help coral reefs survive future warming.

Stable isotopic records of bleaching and endolithic algae blooms in the skeleton of the boulder forming coral Montastraea faveolata

NASA Astrophysics Data System (ADS)

Hartmann, A. C.; Carilli, J. E.; Norris, R. D.; Charles, C. D.; Deheyn, D. D.

2010-12-01

Within boulder forming corals, fixation of dissolved inorganic carbon is performed by symbiotic dinoflagellates within the coral tissue and, to a lesser extent, endolithic algae within the coral skeleton. Endolithic algae produce distinctive green bands in the coral skeleton, and their origin may be related to periods of coral bleaching due to complete loss of dinoflagellate symbionts or “paling” in which symbiont populations are patchily reduced in coral tissue. Stable carbon isotopes were analyzed in coral skeletons across a known bleaching event and 12 blooms of endolithic algae to determine whether either of these types of changes in photosynthesis had a clear isotopic signature. Stable carbon isotopes tended to be enriched in the coral skeleton during the initiation of endolith blooms, consistent with enhanced photosynthesis by endoliths. In contrast, there were no consistent δ13C patterns directly associated with bleaching, suggesting that there is no unique isotopic signature of bleaching. On the other hand, isotopic values after bleaching were lighter 92% of the time when compared to the bleaching interval. This marked drop in skeletal δ13C may reflect increased kinetic fractionation and slow symbiont recolonization for several years after bleaching.

Elevated temperatures and bleaching on a high latitude coral reef: the 1988 Bermuda event

NASA Astrophysics Data System (ADS)

Cook, Clayton B.; Logan, Alan; Ward, Jack; Luckhurst, Brian; Berg, Carl J.

1990-03-01

Sea temperatures were normal in Bermuda during 1987, when Bermuda escaped the episodes of coral bleaching which were prevalent throughout the Caribbean region. Survey transecs in 1988 on 4 6 m reefs located on the rim margin and on a lagoonal patch reef revealed bleaching only of zoanthids between May and July. Transect and tow surveys in August and September revealed bleaching of several coral species; Millepora alcicornis on rim reefs was the most extensively affected. The frequency of bleaching in this species, Montastrea annularis and perhaps Diploria labyrinthiformis was significantly higher on outer reefs than on inshore reefs. This bleaching period coincided with the longest period of elevated sea temperatures in Bermuda in 38 years (28.9 30.9°C inshore, >28° offshore). By December, when temperatures had returned to normal, bleaching of seleractinians continued, but bleaching of M. alcicornis on the outer reefs was greatly reduced. Our observations suggest that corals which normally experience wide temperature ranges are less sensitive to thermal stress, and that high-latitude reef corals are sensitive to elevated temperatures which are within the normal thermal range of corals at lower latitudes.

76 FR 53113 - Guidelines for Designating Biobased Products for Federal Procurement

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-25

.... Information regarding the Federal biobased preferred procurement program (one part of the BioPreferred Program... Request: Extension of a currently approved information collection. Abstract: The USDA BioPreferred Program... that then permit USDA to designate items for preferred procurement under the BioPreferred Program. Once...

Modeling patterns of coral bleaching at a remote Central Pacific atoll.

PubMed

Williams, Gareth J; Knapp, Ingrid S; Maragos, James E; Davy, Simon K

2010-09-01

A mild bleaching event (9.2% prevalence) at Palmyra Atoll occurred in response to the 2009 ENSO, when mean water temperature reached 29.8-30.1 degrees C. Prevalence among both abundant and sparse taxa varied with no clear pattern in susceptibility relating to coral morphology. Seven taxon-specific models showed that turbidity exacerbated while prior exposure to higher background temperatures alleviated bleaching, with these predictors explaining an average 16.3% and 11.5% variation in prevalence patterns, respectively. Positive associations occurred between bleaching prevalence and both immediate temperature during the bleaching event (average 8.4% variation explained) and increased sand cover (average 3.7%). Despite these associations, mean unexplained variation in prevalence equalled 59%. Lower bleaching prevalence in areas experiencing higher background temperatures suggests acclimation to temperature stress among several coral genera, while WWII modifications may still be impacting the reefs via shoreline sediment re-distribution and increased turbidity, exacerbating coral bleaching susceptibility during periods of high temperature stress. Copyright 2010 Elsevier Ltd. All rights reserved.

The 2014 summer coral bleaching event in subtropical Hong Kong.

PubMed

Xie, James Y; Lau, Dickey C C; Kei, Keith; Yu, Vriko P F; Chow, Wing-Kuen; Qiu, Jian-Wen

2017-11-30

We reported a coral bleaching event that occurred in August-September 2014 in Hong Kong waters based on video transect surveys conducted at eight sites. The bleaching affected eight species of corals with different growth forms. Bleaching at seven of the eight study sites was minor, affecting only 0.4-5.2% colonies and 0.8-10.0% coral-covered area. Sharp Island East, however, suffered from a moderate level of bleaching, with 13.1% colonies and 30.1% coral-covered area affected. Examination of the government's environmental monitoring data indicated abnormal water quality conditions preceding and during the bleaching event. Follow-up field surveys of tagged colonies showed that 76% of them had fully recovered, 12% partially recovered, and 12% suffered from mortality. These results indicate that the subtropical corals of Hong Kong are not immune to bleaching, and there is a need to study their responses under climate change scenarios. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bleaching and Hydroprocessing of Algal Biomass-Derived Lipids to Produce Renewable Diesel Fuel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kruger, Jacob S.; Christensen, Earl D.; Dong, Tao

Algal lipids represent a promising feedstock for production of renewable diesel, but there is little information available regarding the integration of pretreatment, extraction, and catalytic upgrading steps. In this work, we examined oil bleaching by two methods and the effects of bleaching on oil deoxygenation over Pd/C and hydroisomerization over Pt/SAPO-11 catalysts. The raw oil was completely deoxygenated and 90% denitrogenated after dilution to 25 wt % in hexanes. The bleaching operations (using either a polar adsorbent or concentrated H 3PO 4) removed 85-90% of the nitrogen and led to 95-99% nitrogen removal after deoxygenation. Oil processability was also improvedmore » by bleaching. Here, the bulk chemistry of the deoxygenation and isomerization was not strongly affected by bleaching, as post-isomerization products with cloud points less than -10 °C and boiling ranges within or close to specification for No. 2 diesel fuel were obtained through 10 h time on stream with or without bleaching.« less

Bleaching and Hydroprocessing of Algal Biomass-Derived Lipids to Produce Renewable Diesel Fuel

DOE PAGES

Kruger, Jacob S.; Christensen, Earl D.; Dong, Tao; ...

2017-08-22

Algal lipids represent a promising feedstock for production of renewable diesel, but there is little information available regarding the integration of pretreatment, extraction, and catalytic upgrading steps. In this work, we examined oil bleaching by two methods and the effects of bleaching on oil deoxygenation over Pd/C and hydroisomerization over Pt/SAPO-11 catalysts. The raw oil was completely deoxygenated and 90% denitrogenated after dilution to 25 wt % in hexanes. The bleaching operations (using either a polar adsorbent or concentrated H 3PO 4) removed 85-90% of the nitrogen and led to 95-99% nitrogen removal after deoxygenation. Oil processability was also improvedmore » by bleaching. Here, the bulk chemistry of the deoxygenation and isomerization was not strongly affected by bleaching, as post-isomerization products with cloud points less than -10 °C and boiling ranges within or close to specification for No. 2 diesel fuel were obtained through 10 h time on stream with or without bleaching.« less

Contrasting patterns of changes in abundance following a bleaching event between juvenile and adult scleractinian corals

NASA Astrophysics Data System (ADS)

Álvarez-Noriega, Mariana; Baird, Andrew H.; Bridge, Tom C. L.; Dornelas, Maria; Fontoura, Luisa; Pizarro, Oscar; Precoda, Kristin; Torres-Pulliza, Damaris; Woods, Rachael M.; Zawada, Kyle; Madin, Joshua S.

2018-06-01

Coral bleaching events have caused extensive mortality on reefs around the world. Juvenile corals are generally less affected by bleaching than their conspecific adults and therefore have the potential to buffer population declines and seed recovery. Here, we use juvenile and adult abundance data at 20 sites encircling Lizard Island, Great Barrier Reef, before and after the 2016 bleaching event to quantify: (1) correlates of changes in juvenile abundance following a bleaching event; (2) differences in susceptibility to extreme thermal stress between juveniles and adults. Declines in juvenile abundance were lower at sites closer to the 20-m-depth contour and higher for Acropora and Pocillopora juveniles than for other taxa. Juveniles of Acropora and Goniastrea were less susceptible to bleaching than adults, but the opposite was true for Pocillopora spp. and taxa in the family Merulinidae. Our results indicate that the potential of the juvenile life stage to act as a buffer during bleaching events is taxon-dependent.

Micro-structural integrity of dental enamel subjected to two tooth whitening regimes.

PubMed

Tanaka, Reina; Shibata, Yo; Manabe, Atsufumi; Miyazaki, Takashi

2010-04-01

Colour modification of tooth enamel has proven successful, but it is unclear how various bleaching applications affect micro-structural integrity of the whitened enamel. To investigate the internal structural integrity of human intact tooth enamel with the application of two commonly used whitening regimes (in-office power bleaching with 35% hydrogen peroxide and home bleaching with 10% carbamide peroxide), evaluations were performed on teeth of identical colour classification. After the bleaching applications, the enamel mineral density was quantified and visualised with micro-computed tomography. The micro-structural differences between the whitened tooth enamel samples were distinctive, though the colour parameter changes within the samples were equivalent. Home bleaching achieved colour modification by demineralisation, whereas in-office bleaching depended on redistribution of the minerals after treatment and subsequent enhanced mineralisation.

Spatial and temporal patterns of mass bleaching of corals in the Anthropocene

NASA Astrophysics Data System (ADS)

Hughes, Terry P.; Anderson, Kristen D.; Connolly, Sean R.; Heron, Scott F.; Kerry, James T.; Lough, Janice M.; Baird, Andrew H.; Baum, Julia K.; Berumen, Michael L.; Bridge, Tom C.; Claar, Danielle C.; Eakin, C. Mark; Gilmour, James P.; Graham, Nicholas A. J.; Harrison, Hugo; Hobbs, Jean-Paul A.; Hoey, Andrew S.; Hoogenboom, Mia; Lowe, Ryan J.; McCulloch, Malcolm T.; Pandolfi, John M.; Pratchett, Morgan; Schoepf, Verena; Torda, Gergely; Wilson, Shaun K.

2018-01-01

Tropical reef systems are transitioning to a new era in which the interval between recurrent bouts of coral bleaching is too short for a full recovery of mature assemblages. We analyzed bleaching records at 100 globally distributed reef locations from 1980 to 2016. The median return time between pairs of severe bleaching events has diminished steadily since 1980 and is now only 6 years. As global warming has progressed, tropical sea surface temperatures are warmer now during current La Niña conditions than they were during El Niño events three decades ago. Consequently, as we transition to the Anthropocene, coral bleaching is occurring more frequently in all El Niño–Southern Oscillation phases, increasing the likelihood of annual bleaching in the coming decades.

NemR Is a Bleach-sensing Transcription Factor*

PubMed Central

Gray, Michael J.; Wholey, Wei-Yun; Parker, Benjamin W.; Kim, Minwook; Jakob, Ursula

2013-01-01

Hypochlorous acid (HOCl), the active component of household bleach, also functions as a powerful antimicrobial during the innate immune response. Despite its widespread use, surprisingly little is known about how cells sense or respond to HOCl. We now demonstrate that Escherichia coli NemR is a redox-regulated transcriptional repressor, which uses the oxidation status of HOCl-sensitive cysteine residues to respond to bleach and related reactive chlorine species. NemR controls bleach-mediated expression of two enzymes required for detoxification of reactive electrophiles: glyoxalase I and N-ethylmaleimide reductase. Both enzymes contribute to bacterial bleach survival. These results provide evidence that bleach resistance relies on the capacity of organisms to specifically sense reactive chlorine species and respond with the up-regulation of enzymes dedicated to detoxification of methylglyoxal and other reactive electrophiles. PMID:23536188

Application of TAED/H2O2 system for low temperature bleaching of crude cellulose extracted from jute fiber

NASA Astrophysics Data System (ADS)

Wen, Zuoqiang; Zou, Linbo; Wang, Weiming

2018-03-01

Tetraacetylethylenediamine (TAED) activated hydrogen peroxide system had been applied for bleaching of crude cellulose extracted from jute fiber. Comparing with conventional hydrogen peroxide bleaching system, those results showed that bleaching temperature and time could be effectively reduced, and a preferable whiteness could be produced under faint alkaline condition. And the optimum conditions for activated bleaching system could be summarized as molar ratio of H2O2/TAED 1:0.7, pH 8, pure hydrogen peroxide 0.09 mol/L, temperature 70 °C and time 60min.

The impact of iron on the bleaching efficacy of hydrogen peroxide in liquid whey systems.

PubMed

Jervis, Suzanne M; Drake, MaryAnne

2013-02-01

Whey is a value-added product that is utilized in many food and beverage applications for its nutritional and functional properties. Whey and whey products are generally utilized in dried ingredient applications. One of the primary sources of whey is from colored Cheddar cheese manufacture that contains the pigment annatto resulting in a characteristic yellow colored Cheddar cheese. The colorant is also present in the liquid cheese whey and must be bleached so that it can be used in ingredient applications without imparting a color. Hydrogen peroxide and benzoyl peroxide are 2 commercially approved chemical bleaching agents for liquid whey. Concerns regarding bleaching efficacy, off-flavor development, and functionality changes have been previously reported for whey bleached with hydrogen peroxide and benzoyl peroxide. It is very important for the dairy industry to understand how bleaching can impact flavor and functionality of dried ingredients. Currently, the precise mechanisms of off-flavor development and functionality changes are not entirely understood. Iron reactions in a bleached liquid whey system may play a key role. Reactions between iron and hydrogen peroxide have been widely studied since the reaction between these 2 relatively stable species can cause great destruction in biological and chemical systems. The actual mechanism of the reaction of iron with hydrogen peroxide has been a controversy in the chemistry and biological community. The precise mechanism for a given reaction can vary greatly based upon the concentration of reactants, temperature, pH, and addition of biological material. In this review, some hypotheses for the mechanisms of iron reactions that may occur in fluid whey that may impact bleaching efficacy, off-flavor development, and changes in functionality are presented. Cheese whey is bleached to remove residual carotenoid cheese colorant. Concerns regarding bleaching efficacy, off-flavor development, and functionality changes have been reported for whey proteins bleached with hydrogen peroxide and benzoyl peroxide. It is very important for the dairy industry to understand how whey bleaching can impact flavor and functionality of dried ingredients. Proposed mechanisms of off-flavor development and functionality changes are discussed in this hypothesis paper. © 2013 Institute of Food Technologists®

Bleaching and enamel surface interactions resulting from the use of highly-concentrated bleaching gels.

PubMed

Grazioli, Guillermo; Valente, Lisia Lorea; Isolan, Cristina Pereira; Pinheiro, Helena Alves; Duarte, Camila Gonçalves; Münchow, Eliseu Aldrighi

2018-03-01

Tooth bleaching is considered a non-invasive treatment, although the use of highly-concentrated products may provoke increased surface roughness and enamel demineralization, as well as postoperative sensitivity. Thus, the aim of this study was to investigate whether hydrogen peroxide (H 2 O 2 ) concentration would affect tooth bleaching effectiveness and the enamel surface properties. Enamel/dentin bovine specimens (6 × 4 mm) were immersed in coffee solution for 7 days and evaluated with a spectrophotometer (Easyshade; baseline), using the CIEL * a * b * color parameters. Hardness was measured using a hardness tester. The specimens were randomly assigned into four groups: one negative control, in which the specimens were not bleached, but they were irradiated with a laser-light source (Whitening Lase II, DMC Equipments); and three groups using distinct H 2 O 2 concentration, namely LP15% (15% Lase Peroxide Lite), LP25% (25% Lase Peroxide Sensy), and LP35% (35% Lase Peroxide Sensy), all products from DMC. The bleached specimens were also irradiated with the laser-light source. After bleaching, all specimens were evaluated using scanning electron microscopy (SEM). pH kinetics and rate was monitored during bleaching. The data were analyzed using ANOVA and Tukey's test (p < 0.05). All bleaching gels produced similar color change (p > 0.05). Concerning hardness, only the LP25% and LP35% significantly reduced hardness after bleaching; also, there was a progressive tendency for a greater percentage reduction in hardness with increased H 2 O 2 concentration of the gel (R 2  = 0.9973, p < 0.001). SEM showed that LP25% and LP35% produced an etching pattern on enamel with prism rods exposure. In conclusion, H 2 O 2 concentration above the 15% level does not increase bleaching effectiveness, and may increase the possibility for alteration of enamel hardness, surface morphology, and acidity of the medium. When using H 2 O 2 -based bleaching agents, dental practitioners should choose for less concentrated gels, e.g., around the 15% level. Copyright © 2017 Elsevier Ltd. All rights reserved.

Environmentally friendly cellulose-based polyelectrolytes in wastewater treatment.

PubMed

Grenda, Kinga; Arnold, Julien; Gamelas, José A F; Rasteiro, Maria G

2017-09-01

Natural-based polyelectrolytes (PELs), with all the advantages coming from being produced from renewable and biodegradable sources, are a potential solution for the removal of dyes from wastewater. In this work, surplus Eucalyptus bleached cellulose fibres from a paper mill were modified to increase the charge and solubility of cellulose. First, reactive aldehyde groups were introduced in the cellulose backbone by periodate oxidation of cellulose. Further modification with alkylammonium produced positively charged cellulose-based PELs. The final products were characterized by several analytical techniques. The PEL with the highest substitution degree of cationic groups was evaluated for its performance in decolouration processes, bentonite being used as aid. This was found to be effective for colour removal of either anionic or cationic dyes. Bio-PELs can thus be considered as very favourable eco-friendly flocculation agents for decolouration of harsh effluents from several industries, considering their biodegradable nature and thus the ability to produce less sludge.

A randomized CIE L*a*b* evaluation of external bleaching therapy effects on fluorotic enamel stains.

PubMed

Knösel, Michael; Attin, Rengin; Becker, Klaus; Attin, Thomas

2008-05-01

To evaluate the effect of external bleaching on the color and luminosity of fluorotic stains and adjacent, normally mineralized enamel areas by means of CIE L*a*b* colorimetry. Eighteen adolescents with mild to moderate fluorotic stains were randomly assigned to either bleaching group A (n = 9) or control group B. Eligibility criteria were fluorotic stained maxillary incisors or canines and the informed consent of the participants and their guardians. Using a colorimeter, CIE L*a*b* values of maxillary incisors and canines were assessed at baseline (T1) in the center of the fluorotic stained area (F1) and at adjacent, normally mineralized enamel areas (F2). Then, external bleaching with Illumine office (30% hydrogen peroxide, Dentsply DeTrey) was performed for 60 minutes, followed by color reassessment (T2). After 14 days (T3), a 2-week home bleaching period with a daily bleaching time of 1 hour with Illumine home (15% carbamide peroxide, Dentsply DeTrey) was conducted with subsequent color determination (T4). After completion of bleaching therapy, 96.0% of all fluorotic areas (F1) and 100% of normal enamel areas (F2) showed a significant change within group A, compared to 29.4% in control group B. Comparing the collective DeltaE (L*, a*, b*) of F1 and F2, 60.0% of all areas showed significant differences after completion of bleaching therapy, compared to 88.0% initially. Of group B sites, 82.4% showed color differences in the beginning (T1) and 88.2% at the end (T4). Whereas a single 1-hour session of in-office bleaching with 30% hydrogen peroxide does not significantly affect the color and luminosity of fluorotic teeth, a 14-day period of home bleaching leads to an assimilation of the color of the fluorotic stain with the color of surrounding enamel areas due to different responses of sound and fluorotic enamel to the bleaching regime.

Massive bleaching of coral reefs induced by the 2010 ENSO, Puerto Cabello, Venezuela.

PubMed

del Mónaco, Carlos; Haiek, Gerard; Narciso, Samuel; Galindo, Miguel

2012-06-01

El Niño Southern Oscillation (ENSO) has generated global coral massive bleaching. The aim of this work was to evaluate the massive bleaching of coral reefs in Puerto Cabello, Venezuela derived from ENSO 2010. We evaluated the bleaching of reefs at five localities both at three and five meter depth. The coral cover and densities of colonies were estimated. We recorded living coral cover, number and diameter of bleached and non-bleached colonies of each coral species. The colonies were classified according to the proportion of bleached area. Satellite images (Modis Scar) were analyzed for chlorophyll-a concentration and temperature in August, September, October and November from 2008-2010. Precipitation, wind speed and air temperature information was evaluated in meteorological data for 2009 and 2010. A total of 58.3% of colonies, belonging to 11 hexacoral species, were affected and the greatest responses were observed in Colpophyllia natans, Montastraea annularis and Montastraeafaveolata. The most affected localities were closer to the mainland and had a bleached proportion up to 62.73+/-36.55%, with the highest proportion of affected colonies, whereas the farthest locality showed 20.25+/-14.00% bleached and the smallest proportion. The salinity in situ varied between 30 and 33ppm and high levels of turbidity were observed. According to the satellite images, in 2010 the surface water temperature reached 31 degree C in August, September and October, and resulted higher than those registered in 2008 and 2009. Regionally, chlorophyll values were higher in 2010 than in 2008 and 2009. The meteorological data indicated that precipitation in November 2010 was three times higher than in November 2009. Massive coral bleaching occurred due to a three month period of high temperatures followed by one month of intense ENSO-associated precipitation. However, this latter factor was likely the trigger because of the bleaching gradient observed.

Evaluation of the Efficacy and Color Stability of Two Different At-Home Bleaching Systems on Teeth of Different Shades: A Randomized Controlled Clinical Trial.

PubMed

Aka, Betül; Celik, Esra Uzer

2017-09-01

This randomized controlled clinical trial compared the bleaching efficacy of two different at-home bleaching systems on teeth of different shades and their color stability after a 6-month follow-up. Ninety-two patients (777 teeth) were randomly divided into three groups: (a) negative control, (b) patients treated with a custom-made tray containing 10% carbamide peroxide (10% CP/PF) (Opalescence PF), and (c) patients treated with a pre-loaded tray containing 6% hydrogen peroxide (6% HP/Go) (Opalescence Go). Teeth in all groups were divided into three sub-groups according to the VITA Classic Shade Guide: light (A1-C1), medium dark (C2-B3), and dark (A3.5-C4). Bleaching systems were performed in accordance with manufacturers' instructions for 14 days. The color values were measured at the baseline, 10 days and 14 days of bleaching, 2 weeks, and 6 months after bleaching. Three-way ANOVA and Mann-Whitney U tests were used for statistical analysis (α = 0.05). Irrespective of original shade, both bleaching groups showed significantly higher ΔE* values than the control groups, and the ΔE* values were significantly higher in the 10% CP/PF groups than those in the 6% HP/Go groups (p < 0.05). In both bleaching systems, the dark teeth showed higher ΔE* values than the light teeth (p < 0.05). The ΔE* values decreased significantly only in the 10% CP/PF groups after 6 months (p < 0.05). Both bleaching agents produced a bleaching effect, but 10% CP/PF was more effective. A pre-loaded tray system may be used for dental bleaching, but it is still less effective than conventional a 10% carbamide peroxide system, irrespective of the initial shade. (J Esthet Restor Dent 29:325-338, 2017). © 2017 Wiley Periodicals, Inc.

A Crucial Time for Reefs: Climate Change, El Niño, and the 2014-16 Global Bleaching Event

NASA Astrophysics Data System (ADS)

Eakin, C. M.; Liu, G.; Geiger, E.; Heron, S. F.; Skirving, W. J.; De La Cour, J. L.; Strong, A. E.; Tirak, K.; Burgess, T.

2016-02-01

Anthropogenic climate change has caused an increase in the frequency and intensity of coral bleaching, mortality, and other impacts detrimental to the health and survival of coral reefs around the world. In 2014, a global-scale bleaching event, anticipated to last two years or more, began in the Pacific Ocean. Severe bleaching was documented in Guam, the Commonwealth of the Northern Mariana Islands, Hawaii, and the Marshall Islands, among other locations. By mid-2015, severe bleaching had reached many south Pacific Islands and islands of the central to eastern equatorial Pacific, especially Kiribati and Howland and Baker Islands. Bleaching followed in the Indian Ocean, and at the time of this writing is again striking Hawaii, and parts of the Caribbean. As the ongoing El Niño continues to strengthen, long-term outlooks suggest the cycle of bleaching will continue into 2016 in at least the Pacific and Indian Oceans. Caribbean bleaching may follow again in 2016 if this event follows historical patterns. Warming of the global ocean, the El Niño, a new Pacific oceanic feature known as "The Blob", and other patterns are imposing thermal stress capable of causing widespread negative impacts on reefs in many countries and archipelagos. If a subsequent La Niña follows, as is often the case, even more reefs will be subjected to stressful high temperatures. This is resulting in widespread bleaching, disease, and mortality at a frequency and intensity predicted in climate models nearly two decades ago. The question now is if we are seeing the onset of annually returning coral bleaching or if this is just a hint of conditions coming in future decades. This presentation will discuss the latest information on the ongoing third global bleaching event and the impacts it may have on the biology, ecology, and potential for conservation and restoration of corals and coral reefs worldwide.

Skeletal light-scattering accelerates bleaching response in reef-building corals.

PubMed

Swain, Timothy D; DuBois, Emily; Gomes, Andrew; Stoyneva, Valentina P; Radosevich, Andrew J; Henss, Jillian; Wagner, Michelle E; Derbas, Justin; Grooms, Hannah W; Velazquez, Elizabeth M; Traub, Joshua; Kennedy, Brian J; Grigorescu, Arabela A; Westneat, Mark W; Sanborn, Kevin; Levine, Shoshana; Schick, Mark; Parsons, George; Biggs, Brendan C; Rogers, Jeremy D; Backman, Vadim; Marcelino, Luisa A

2016-03-21

At the forefront of ecosystems adversely affected by climate change, coral reefs are sensitive to anomalously high temperatures which disassociate (bleaching) photosynthetic symbionts (Symbiodinium) from coral hosts and cause increasingly frequent and severe mass mortality events. Susceptibility to bleaching and mortality is variable among corals, and is determined by unknown proportions of environmental history and the synergy of Symbiodinium- and coral-specific properties. Symbiodinium live within host tissues overlaying the coral skeleton, which increases light availability through multiple light-scattering, forming one of the most efficient biological collectors of solar radiation. Light-transport in the upper ~200 μm layer of corals skeletons (measured as 'microscopic' reduced-scattering coefficient, μ'(S,m)), has been identified as a determinant of excess light increase during bleaching and is therefore a potential determinant of the differential rate and severity of bleaching response among coral species. Here we experimentally demonstrate (in ten coral species) that, under thermal stress alone or combined thermal and light stress, low-μ'(S,m) corals bleach at higher rate and severity than high-μ'(S,m) corals and the Symbiodinium associated with low-μ'(S,m) corals experience twice the decrease in photochemical efficiency. We further modelled the light absorbed by Symbiodinium due to skeletal-scattering and show that the estimated skeleton-dependent light absorbed by Symbiodinium (per unit of photosynthetic pigment) and the temporal rate of increase in absorbed light during bleaching are several fold higher in low-μ'(S,m) corals. While symbionts associated with low-[Formula: see text] corals receive less total light from the skeleton, they experience a higher rate of light increase once bleaching is initiated and absorbing bodies are lost; further precipitating the bleaching response. Because microscopic skeletal light-scattering is a robust predictor of light-dependent bleaching among the corals assessed here, this work establishes μ'(S,m) as one of the key determinants of differential bleaching response.

Flotation of Toxocara canis Eggs in Commercial Bleach and Effects of Bleach Treatment Times on Larval Development in These Eggs.

PubMed

von Dohlen, Alexa Rosypal; Houk-Miles, Alice E; Zajac, Anne M; Lindsay, David S

2017-04-01

Toxocara canis is a common intestinal nematode of young dogs. Puppies contaminate the environment with large numbers of eggs that can embryonate and become infective in less than a month. Embryonated eggs are infectious for humans and other paratenic hosts. Most T. canis infections in humans are asymptomatic; however, migration of T. canis larvae in the eye and in the central nervous system can result in vision loss, blindness, and even death. The eggs of T. canis are highly resistant to harsh environmental conditions and routinely used chemical disinfectants. The objective of this study was to evaluate the effects of full-strength commercial bleach (5.25% sodium hypochlorite solution) treatment on development of T. canis eggs and to report our serendipitous finding that T. canis eggs in dog feces can float in passive fecal flotation tests using bleach. We also demonstrated that T. canis eggs could be identified using the McMaster's fecal eggs counting test using 100% bleach. Toxocara canis eggs collected from the feces of naturally infected 4-8 wk old puppies were treated with full-strength bleach (5.25% sodium hypochlorite solution) for 15 min, 30 min, 60 min, and 120 min; washed free of bleach smell by centrifugation; and resuspended in 0.1 N sulfuric acid solution to undergo larval development at room temperature for 18 days after exposure to bleach. Motile larvae were observed in T. canis eggs in all groups treated for 15-120 min and eggs continuously exposed to bleach for 18 days. Our results indicate that bleach may not be an appropriate disinfectant for dog kennels, cages, or laboratory utensils and work surfaces. Toxocara canis eggs are resistant to bleach treatment and continue to pose a risk for canine and human infections. Further study is needed to find the most appropriate methods for disinfection and removal of eggs to reduce the risk of transmission of this parasite.

Bleaching of reef coelenterates in the San Blas Islands, Panama

NASA Astrophysics Data System (ADS)

Lasker, Howard R.; Peters, Esther C.; Coffroth, Mary Alice

1984-12-01

Starting in June 1983, 25 species of hermatypic corals, gorgonians, hydrocorals, anemones and zoanthids in the San Blas Islands, Panama, began showing signs of a loss of colour leading in some cases to a white “bleached” appearance. Histologic examination of six coral species indicated that bleaching was associated with drastic reductions in the density of zooxanthellae and with the atrophy and necrosis of the animal tissue. The severity of the bleaching varied among species and many species were unaffected. The species most extensively affected were: Agaricia spp., which became completely bleached and frequently died; Montastraea annularis which bleached and continued to survive; and Millepora spp. which bleached white but quickly regained their colouration. Shallow reefs dominated by Agaricia spp. suffered the most extensive bleaching. At one site, Pico Feo, 99% of the Agaricia (32% of the living cover) was bleached. On fore reers, which were dominated by Agaricia spp. and M. annularis, the proportion of M. annularis bleached ranged from 18 to 100% and that of Agaricia spp. from 30 to 53%. Transects at Sail Rock and House Reef were surveyed in August 1983 and January 1984. At those sites, 53% of the Agaricia cover died between August and January. The remaining living cover of Agaricia and of all other species exhibited normal colouration in January. Salinity and temperature were monitored every second day at 4 m depth between May 10 and August 28, 1983 at one of the localities. Bleaching was first observed within two weeks of a 2 °C rise in temperature which occurred in late May 1983. Temperatures remained at or above 31.5 °C for the following 3 weeks and were at or above 30 °C for an additional 4 weeks. The bleaching of corals in the San Blas was most likely due to those elevanted temperatures.

Enhanced photoluminescence and characterization of multicolor carbon dots using plant soot as a carbon source.

PubMed

Tan, Mingqian; Zhang, Lingxin; Tang, Rong; Song, Xiaojie; Li, Yimin; Wu, Hao; Wang, Yanfang; Lv, Guojun; Liu, Wanfa; Ma, Xiaojun

2013-10-15

Carbon dots (C-dots) are a class of novel fluorescent nanomaterials, which have drawn great attention for their potential applications in bio-nanotechnology. Multicolor C-dots have been synthesized by chemical nitric acid oxidation using the reproducible plant soot as raw material. TEM analysis reveals that the prepared C-dots have an average size of 3.1 nm. The C-dots are well dispersed in aqueous solution and are strongly fluorescent under the irradiation of ultra-violet light. X-ray photoelectron spectroscopy characterization demonstrates that the O/C atomic ratio for C-dots change to from 0.207 to 0.436 due to the chemical oxidation process. The photo bleaching experiment reveals that the C-dots show excellent photostability as compared with the conventional organic dyes, fluorescein and rhodamine B. The fluorescence intensity of the C-dots did not change significantly in the pH range of 3-10. To further enhance the fluorescence quantum yield, the C-dots were surface modified with four types of passivation ligands, 4,7,10-trioxa-1,13-tridecanediamine (TTDDA), poly-L-lysine (PLL), cysteine and chitosan and the fluorescence quantum yields of the TTDDA, PLL, cysteine and chitosan passivated C-dots were improved 1.53-, 5.94-, 2.00- and 3.68-fold, respectively. Fourier-transform infrared (FTIR) spectra were employed to characterize the surface groups of the C-dots. The bio-application of the C-dots as fluorescent bio-probes was evaluated in cell imaging and ex vivo fish imaging, which suggests that the C-dots may have potential applications in biolabeling and bioimaging. Copyright © 2013 Elsevier B.V. All rights reserved.

In situ observations of coral bleaching in the central Saudi Arabian Red Sea during the 2015/2016 global coral bleaching event.

PubMed

Monroe, Alison A; Ziegler, Maren; Roik, Anna; Röthig, Till; Hardenstine, Royale S; Emms, Madeleine A; Jensen, Thor; Voolstra, Christian R; Berumen, Michael L

2018-01-01

Coral bleaching continues to be one of the most devastating and immediate impacts of climate change on coral reef ecosystems worldwide. In 2015, a major bleaching event was declared as the "3rd global coral bleaching event" by the United States National Oceanic and Atmospheric Administration, impacting a large number of reefs in every major ocean. The Red Sea was no exception, and we present herein in situ observations of the status of coral reefs in the central Saudi Arabian Red Sea from September 2015, following extended periods of high temperatures reaching upwards of 32.5°C in our study area. We examined eleven reefs using line-intercept transects at three different depths, including all reefs that were surveyed during a previous bleaching event in 2010. Bleaching was most prevalent on inshore reefs (55.6% ± 14.6% of live coral cover exhibited bleaching) and on shallower transects (41% ± 10.2% of live corals surveyed at 5m depth) within reefs. Similar taxonomic groups (e.g., Agariciidae) were affected in 2015 and in 2010. Most interestingly, Acropora and Porites had similar bleaching rates (~30% each) and similar relative coral cover (~7% each) across all reefs in 2015. Coral genera with the highest levels of bleaching (>60%) were also among the rarest (<1% of coral cover) in 2015. While this bodes well for the relative retention of coral cover, it may ultimately lead to decreased species richness, often considered an important component of a healthy coral reef. The resultant long-term changes in these coral reef communities remain to be seen.

Seasonal mesophotic coral bleaching of Stylophora pistillata in the Northern Red Sea.

PubMed

Nir, Orit; Gruber, David F; Shemesh, Eli; Glasser, Eliezra; Tchernov, Dan

2014-01-01

Coral bleaching occurs when environmental stress induces breakdown of the coral-algae symbiosis and the host initiates algae expulsion. Two types of coral bleaching had been thoroughly discussed in the scientific literature; the first is primarily associated with mass coral bleaching events; the second is a seasonal loss of algae and/or pigments. Here, we describe a phenomenon that has been witnessed for repeated summers in the mesophotic zone (40-63 m) in the northern Red Sea: seasonal bleaching and recovery of several hermatypic coral species. In this study, we followed the recurring bleaching process of the common coral Stylophora pistillata. Bleaching occurred from April to September with a 66% decline in chlorophyll a concentration, while recovery began in October. Using aquarium and transplantation experiments, we explored environmental factors such as temperature, photon flux density and heterotrophic food availability. Our experiments and observations did not yield one single factor, alone, responsible for the seasonal bleaching. The dinoflagellate symbionts (of the genus Symbiodinium) in shallow (5 m) Stylophora pistillata were found to have a net photosynthetic rate of 56.98-92.19 µmol O2 cm(-2) day(-1). However, those from mesophotic depth (60 m) during months when they are not bleached are net consumers of oxygen having a net photosynthetic rate between -12.86 - (-10.24) µmol O2 cm(-2) day(-1). But during months when these mesophotic corals are partially-bleached, they yielded higher net production, between -2.83-0.76 µmol O2 cm(-2) day(-1). This study opens research questions as to why mesophotic zooxanthellae are more successfully meeting the corals metabolic requirements when Chl a concentration decreases by over 60% during summer and early fall.

Coscinaraea marshae corals that have survived prolonged bleaching exhibit signs of increased heterotrophic feeding

NASA Astrophysics Data System (ADS)

Bessell-Browne, Pia; Stat, Michael; Thomson, Damian; Clode, Peta L.

2014-09-01

Colonies of Coscinaraea marshae corals from Rottnest Island, Western Australia have survived for more than 11 months in various bleached states following a severe heating event in the austral summer of 2011. These colonies are situated in a high-latitude, mesophotic environment, which has made their long-term survival of particular interest as such environments typically suffer from minimal thermal pressures. We have investigated corals that remain unbleached, moderately bleached, or severely bleached to better understand potential survival mechanisms utilised in response to thermal stress. Specifically, Symbiodinium (algal symbiont) density and genotype, chlorophyll- a concentrations, and δ13C and δ15N levels were compared between colonies in the three bleaching categories. Severely bleached colonies housed significantly fewer Symbiodinium cells ( p < 0.05) and significantly reduced chlorophyll- a concentrations ( p < 0.05), compared with unbleached colonies. Novel Symbiodinium clade associations were observed for this coral in both severely and moderately bleached colonies, with clade C and a mixed clade population detected. In unbleached colonies, only clade B was observed. Levels of δ15N indicate that severely bleached colonies are utilising heterotrophic feeding mechanisms to aid survival whilst bleached. Collectively, these results suggest that these C. marshae colonies can survive with low symbiont and chlorophyll densities, in response to prolonged thermal stress and extended bleaching, and increase heterotrophic feeding levels sufficiently to meet energy demands, thus enabling some colonies to survive and recover over long time frames. This is significant as it suggests that corals in mesophotic and high-latitude environments may possess considerable plasticity and an ability to tolerate and adapt to large environmental fluctuations, thereby improving their chances of survival as climate change impacts coral ecosystems worldwide.

Effect of Er,Cr:YSGG laser on the surface of composite restoratives during in-office tooth bleaching.

PubMed

Dionysopoulos, Dimitrios; Strakas, Dimitrios; Tsitrou, Effrosyni; Tolidis, Kosmas; Koumpia, Effimia

2016-07-01

The aim of this in vitro study was to investigate the effect of Er,Cr:YSGG laser on the surface roughness and microhardness of various composite restoratives during in-office tooth bleaching. Five highly viscous composite restoratives and three flowable composite restoratives were investigated. Thirty cylindrical specimens of each material were made using Teflon molds. The specimens of each composite were randomly divided into three groups (n = 10). Group 1 specimens did not receive bleaching treatment, group 2 received a conventional in-office bleaching treatment, and group 3 received a laser-assisted in-office bleaching treatment using an Er,Cr:YSGG laser. Two-way ANOVA was used to determine significant interactions between materials and bleaching methods. One-way ANOVA and Tukey's post hoc test were used to compare the mean surface microhardness and roughness between materials for each treatment group (a = 0.05). Τhere were no significant differences in surface microhardness between the two bleached experimental groups for all the tested composites (p > 0.05). The reduction of surface microhardness after bleaching procedures ranged from 0.72 to 16.93 % for the specimens received conventional treatment and from 1.30 to 11.51 % for those received laser-assisted treatment. Moreover, there were no significant differences in Ra values between the experimental groups (p > 0.05) in all cases. The increase of surface roughness after the bleaching treatments was negligible and was between 0.43 and 4.78 %. The use of Er,Cr:YSGG laser during in-office tooth bleaching treatment did not affect the surface microhardness and roughness of the tested composite restorative materials.

In situ observations of coral bleaching in the central Saudi Arabian Red Sea during the 2015/2016 global coral bleaching event

PubMed Central

Ziegler, Maren; Roik, Anna; Röthig, Till; Hardenstine, Royale S.; Emms, Madeleine A.; Jensen, Thor; Voolstra, Christian R.; Berumen, Michael L.

2018-01-01

Coral bleaching continues to be one of the most devastating and immediate impacts of climate change on coral reef ecosystems worldwide. In 2015, a major bleaching event was declared as the “3rd global coral bleaching event” by the United States National Oceanic and Atmospheric Administration, impacting a large number of reefs in every major ocean. The Red Sea was no exception, and we present herein in situ observations of the status of coral reefs in the central Saudi Arabian Red Sea from September 2015, following extended periods of high temperatures reaching upwards of 32.5°C in our study area. We examined eleven reefs using line-intercept transects at three different depths, including all reefs that were surveyed during a previous bleaching event in 2010. Bleaching was most prevalent on inshore reefs (55.6% ± 14.6% of live coral cover exhibited bleaching) and on shallower transects (41% ± 10.2% of live corals surveyed at 5m depth) within reefs. Similar taxonomic groups (e.g., Agariciidae) were affected in 2015 and in 2010. Most interestingly, Acropora and Porites had similar bleaching rates (~30% each) and similar relative coral cover (~7% each) across all reefs in 2015. Coral genera with the highest levels of bleaching (>60%) were also among the rarest (<1% of coral cover) in 2015. While this bodes well for the relative retention of coral cover, it may ultimately lead to decreased species richness, often considered an important component of a healthy coral reef. The resultant long-term changes in these coral reef communities remain to be seen. PMID:29672556

Dentin bond strength and nanoleakage of the adhesive interface after intracoronal bleaching.

PubMed

Cavalli, Vanessa; Sebold, Maicon; Shinohara, Mirela Sanae; Pereira, Patrícia Nóbrega Rodrigues; Giannini, Marcelo

2018-04-01

This study evaluated dentin bond strength (BS) and nanoleakage of non- and pre-etched dentin immediately (T 0 ,), 7 days (T 7 ), and 14 days (T 14 ) after bleaching. Bovine incisors (150) were selected and half of them submitted to intrapulpal dentin etching (e). Non- and pre-etched dentin were subjected to the following (n = 15): no bleaching/control (C); 35% carbamide peroxide (CP); 35% hydrogen peroxide (35% HP); 25% hydrogen peroxide (25% HP); and sodium perborate (SP). Bleaching agents were applied to the pulp chamber four times within a 72-h interval. Afterwards, pulp chamber dentin was prepared for the BS test at different evaluation times (n = 5): T 0 , T 7 , and T 14 . Composite blocks were built on pulp chamber and sectioned in slices. Slices were reduced to an hour-glass shape with a cross-sectional area of 0.8 mm 2 and submitted to microtensile BS test. Two additional specimens for each group were prepared for nanoleakage evaluation by transmission electron microscopy (TEM). Results were analyzed by ANOVA (two-way) and Dunnett's test (p < .05). BS decreased immediately after intracoronal bleaching for both sound and pre-etched dentin (p < .05). At T 14 , the BS of non-etched bleached dentin increased for all groups, whereas the pre-etched SPe group presented BS similar to the Ce. Nanoleakage within the hybrid layer was perceptible immediately after bleaching, although a decrease in nanoleakage was observed for all groups at T 14 . Adhesive restorations should be performed 7-14 days after bleaching, according to the bleaching agent used. Intracoronal bleaching should be performed preferably with sodium perborate if previous dentin etching is applied. © 2018 Wiley Periodicals, Inc.

Childhood Physical and Sexual Abuse in Caribbean Young Adults and Its Association with Depression, Post-Traumatic Stress, and Skin Bleaching.

PubMed

James, Caryl; Seixas, Azizi A; Harrison, Abigail; Jean-Louis, Girardin; Butler, Mark; Zizi, Ferdinand; Samuels, Alafia

2016-01-01

The global prevalence of skin depigmentation/skin bleaching among blacks, estimated at 35%, is on the rise and is associated with a host of negative health and medical consequences. Current etiological approaches do not fully capture the emotional and psychological underpinnings of skin bleaching. The current study investigated the potential mediating role of depression, or post-traumatic stress symptoms (avoidance and hyperarousal) on the relationship between childhood physical and sexual abuse (CPSA) and skin bleaching. A total of 1226 university participants (ages 18-30 years and 63.4% female) from three Caribbean countries (Jamaica, Barbados, and Grenada) provided data for the current analysis. They all completed self-reported measures of general demographic information along with the short screening scale for posttraumatic stress disorder (DSM-IV), childhood trauma, and skin bleaching questions. The prevalence of skin bleaching in our study was 25.4%. Our findings showed that individuals who bleached their skin were more likely to have been abused as children (21.6% versus 13.5%, p<0.001), were more likely to have significant symptoms of trauma (34.1% versus 24.0%, p=0.005), and were more likely to have significant depression (43.7% versus 35.1%, p=0.032). We found that trauma-related hyperarousal symptoms positively mediated the relationship between childhood physical and sexual abuse and skin bleaching (Indirect Effect=0.03, p<0.05), while avoidance (Indirect Effect=0.000, p>0.05) and depressive (Indirect Effect=0.005, p>0.05) symptoms did not. The presence of trauma symptoms and childhood physical and sexual abuse (CPSA) may increase the likelihood of skin bleaching. Findings suggest that further exploration is needed to ascertain if the presence of skin bleaching warrants being also screened for trauma.

Decalcification prevention around orthodontic brackets bonded to bleached enamel using different topical agents.

PubMed

Msallam, Ferial Ahmed; Grawish, Mohammed El-Awady; Hafez, Ahmad Mohammed; Abdelnaby, Yasser Lotfy

2017-12-01

The present study was conducted to evaluate the effect of different topical agents utilized for prevention of enamel decalcification around orthodontic brackets bonded to bleached and non-bleached enamel. Human maxillary premolars (n = 120) were divided into two equal groups. Teeth in group I were left without bleaching while those in group II were bleached with Vivastyle gel. Metal brackets were bonded to all the teeth using light-cured adhesive. Each group was divided into six equal subgroups (A, B, C, D, E, and F). In subgroup A, no material was applied (control). In subgroups B, C, D, E, and F, the following materials were applied respectively: Profluorid varnish, Enamel Pro Varnish, Ortho-Choice Ortho-Coat, GC Tooth Mousse, and GC MI Paste Plus. All teeth were cycled in a demineralization solution/artificial saliva for 15 days. Laser fluorescence was used to measure the level of enamel mineralization. The data were statistically analyzed. Regarding the non-bleaching subgroups, all studied material revealed significant demineralization reduction in comparison to the control subgroup (P < 0.05). Ortho-Choice Ortho-Coat revealed the highest significant effect while GC Tooth Mousse showed the least effect. In bleached subgroups, Profluorid varnish, Enamel Pro Varnish, and Ortho-Choice Ortho-Coat significantly reduced demineralization (P < 0.05) while either GC MI Paste Plus or GC Tooth Mousse had no significant effects (P > 0.05). Ortho-Choice Ortho-Coat, and Profluorid and Enamel Pro varnishes could be utilized successfully to reduce enamel demineralization around brackets bonded to either bleached or non-bleached enamel. GC MI Paste Plus and GC Tooth Mousse were effective only in non-bleached enamel.

Spectrophotometric analysis of the effectiveness of a novel in-office laser-assisted tooth bleaching method using Er,Cr:YSGG laser.

PubMed

Dionysopoulos, Dimitrios; Strakas, Dimitrios; Tolidis, Kosmas; Tsitrou, Effrosyni; Koumpia, Effimia; Koliniotou-Koumpia, Eugenia

2017-11-01

The purpose of this in vitro study was to compare the effectiveness of a novel Er,Cr:YSGG laser-assisted in-office tooth bleaching method with a conventional method by spectrophotometric analysis of the tooth color change. Furthermore, the influence of the application time of the bleaching gel on the effectiveness of the methods and the maintenance of the results 7 days and 1 month after the treatments were also evaluated. Twenty-four bovine incisors were stained and randomly distributed into four groups. Group 1 specimens received an in-office bleaching treatment with 35% H 2 O 2 for 2 × 15 min. Group 2 specimens received the same treatment but with extended application time (2 × 20 min). In Group 3, the same in-office bleaching procedure (2 × 15 min) was carried out as that in Group 1, using Er,Cr:YSGG laser irradiation for 2 × 15 s on each specimen to catalyze the reaction of H 2 O 2 breakdown. Group 4 specimens received the same bleaching treatment as Group 3 but with extended application time (2 × 20 min). Er,Cr:YSGG laser-assisted tooth bleaching treatment is more effective than the conventional treatment regarding color change of the teeth. Application time of the bleaching agent may influence the effectiveness of the methods. The color change of the tested treatments decreases after 7 days and 1 month. The clinical relevance of this study is that this novel laser-assisted bleaching treatment may be more advantageous in color change and application time compared to the conventional bleaching treatment.

[Assessment of tooth bleaching efficacy with spectrophotometer].

PubMed

Zhu, Wenhao; Liu, Chang; Pan, Jie

2014-06-01

To analyze the changes in CIE L*, a*, and b* at cervical, body, and incisal sites after tooth bleaching by using a spectrophotometer. Sixty-seven intact and healthy maxillary central incisors were in-vestigated. These incisors were darker than A3 according to the Vita Classical shade guide. The CIE tooth shade parameters L*, a*, and b* were simultaneously recorded at three tooth areas (cervical, body, and incisal) with a spectrophotometer before and after tooth bleaching (35%H2O2 coordinating with Beyond whitening accelerator irradiating). The shade dif-ferential (DeltaE) was calculated. ANOVA, paired t-test, and Pearson correlation analysis were used for data analysis. The efficacy rates of tooth bleaching were satisfactory, with 86.6%, 86.6%, and 85.1% in the cervical, body, and incisal sites, respectively. The average values of DeltaE were 5.09, 4.44, and 4.40 in the cervical, body, and incisal sites. Tooth bleaching significantly increased L* and significantly decreased a* and b* in all tooth areas (P < 0.01). The decreasing range of Deltab* was more than the increasing range of DeltaL* at the cervical site; opposite results were observed at the incisal site. A positive correlation was detected between baseline b* and DeltaE. The spectrophotometer could objectively evaluate the whitening effect of tooth bleaching at the different tooth sites. The tooth bleaching system (35%H202 coordinating with Beyond whitening accelerator irradiating) exerts powerful bleaching actions in most of the tooth areas investigated. The order of tooth bleaching effectiveness is cervicalbody>incisal. Yellow coloration is decreased mainly at the cervical site, and brightness was increased mostly at theincisal site. The effectiveness of tooth bleaching increases as the baseline b* value increases.

In-office tooth bleaching with 38% hydrogen peroxide promotes moderate/severe pulp inflammation and production of ll-1β, TNF-β, GPX, FGF-2 and osteocalcin in rats.

PubMed

Silva-Costa, Renata Suellen Galvão da; Ribeiro, Andressa Eveline de Lima; Assunção, Isauremi Vieira de; Araújo Júnior, Raimundo Fernandes de; Araújo, Aurigena Antunes de; Guerra, Gerlane Coelho Bernardo; Borges, Boniek Castillo Dutra

2018-06-11

To study the intensity of inflammatory infiltrate and production of interleukin-1β (ll-1β), tumor necrosis factor-β (TNF-β), fibroblast growth factor-2 (FGF-2), glutathione peroxidase (GPX), and osteocalcin in response to in-office tooth bleaching in rats. Twenty male Wistar rats were randomized into four groups (n=5) according to the received treatment (tooth bleaching or no treatment - control) and the period of euthanasia after treatment (24 h or 10 days). We performed tooth bleaching using a 38% hydrogen peroxide gel on maxillary and mandibular incisors. After euthanasia, incisors (20 per group) were processed for histological analysis, immunohistochemistry staining of ll-1β, TNF-β, FGF-2 and GPX and osteocalcin by immunofluorescence. We analyzed data using the Mann-Whitney and Kruskal-Wallis/Dunn tests (p<0.05). The bleached groups presented statistically significant differences regarding the pulp inflammation stage compared with the control groups. Bleached teeth showed moderate/severe inflammatory infiltrate and control groups presented absent inflammatory cells or a negligible number of mononuclear cells (p<0.001) at two times (24 h and 10 days). There was strong staining for ll-1β, TNF-β, and GPX in bleached groups at 24 h and strong staining for ll-1β, TNF-β, GPX and FGF-2 at 10 days. After 10 days of tooth bleaching, the bleached group showed a statistically superior amount of osteocalcin than the other groups (p<0.01). Tooth bleaching with 38% hydrogen peroxide causes severe pulp inflammation, but characteristics of tissue repair after 10 days.

Effect of CO2, Nd:YAG and Er:YAG Lasers on Microtensile Bond Strength of Composite to Bleached-Enamel.

PubMed

Basir, Mahshid Mohammadi; Rezvani, Mohammad Bagher; Chiniforush, Nasim; Moradi, Zohreh

2016-01-01

Tooth restoration immediately after bleaching is challenging due to the potential problems in achieving adequate bond strength. The aim of this study was to evaluate the effect of surface treatment with ER:YAG, ND:YAG, CO2 lasers and 10% sodium ascorbate solution on immediate microtensile bond strength of composite resin to recently bleached enamel. Ninety sound molar teeth were randomly divided into three main groups (n:30) : NB (without bleaching), HB (bleached with 38% carbamide peroxide) and OB (bleached with Heydent bleaching gel assisted by diode laser). Each group was divided into five subgroups (n:6) : Si (without surface treatment), Er (Er:YAG laser), CO2 (CO2 laser), Nd (Nd:YAG laser) and As (Immersion in 10% sodium ascorbate solution). The bonding system was then applied and composite build-ups were constructed. The teeth were sectioned by low speed saw to obtain enamel- resin sticks and submitted to microtensile bond testing. Statistical analyses were done using two- way ANOVA, Tukey and Tamhane tests. µTBS of bleached teeth irradiated with ND:YAG laser was not significantly different from NB-Nd group. Microtensile bond strength of OB-Er group was higher than NB-Er and HB-Er groups. The mean µTBS of HB-CO2 group was higher than NB-CO2 group; the average µTBS of HB-As and OB-As groups was also higher than NB-As group. Use of Nd:YAG, CO2 lasers and 10% sodium ascorbate solution could improve the bond strength in home-bleached specimens. Application of ND:YAG laser on nonbleached specimens and Er:YAG laser on office-bleached specimens led to the highest µTBS in comparison to other surface treatments in each main group.

Influence of habitat degradation on fish replenishment

NASA Astrophysics Data System (ADS)

McCormick, M. I.; Moore, J. A. Y.; Munday, P. L.

2010-09-01

Temperature-induced coral bleaching is a major threat to the biodiversity of coral reef ecosystems. While reductions in species diversity and abundance of fish communities have been documented following coral bleaching, the mechanisms that underlie these changes are poorly understood. The present study examined the impacts of coral bleaching on the early life-history processes of coral reef fishes. Daily monitoring of fish settlement patterns found that ten times as many fish settled to healthy coral than sub-lethally bleached coral. Species diversity of settling fishes was least on bleached coral and greatest on dead coral, with healthy coral having intermediate levels of diversity. Laboratory experiments using light-trap caught juveniles showed that different damselfish species chose among healthy, bleached and dead coral habitats using different combinations of visual and olfactory cues. The live coral specialist, Pomacentrus moluccensis, preferred live coral and avoided bleached and dead coral, using mostly visual cues to inform their habitat choice. The habitat generalist, Pomacentrus amboinensis, also preferred live coral and avoided bleached and dead coral but selected these habitats using both visual and olfactory cues. Trials with another habitat generalist, Dischistodus sp., suggested that vision played a significant role. A 20 days field experiment that manipulated densities of P. moluccensis on healthy and bleached coral heads found an influence of fish density on juvenile weight and growth, but no significant influence of habitat quality. These results suggests that coral bleaching will affect settlement patterns and species distributions by influencing the visual and olfactory cues that reef fish larvae use to make settlement choices. Furthermore, increased fish density within the remaining healthy coral habitats could play an important role in influencing population dynamics.

RECOVERY OF ROD PHOTORESPONSES IN ABCR-DEFICIENT MICE

PubMed Central

Pawar, Ambarish S.; Qtaishat, Nasser M.; Little, Deborah M.; Pepperberg, David R.

2010-01-01

Purpose ABCR protein in the rod outer segment is thought to facilitate movement of the all-trans retinal photoproduct of rhodopsin bleaching out of the disk lumen. We investigated the extent to which ABCR deficiency affects post-bleach recovery of the rod photoresponse in ABCR-deficient (abcr−/−) mice. Methods Electroretinographic (ERG) a-wave responses were recorded from abcr−/− mice and two control strains. Using a bright probe flash, we examined the course of rod recovery following fractional rhodopsin bleaches of ~10−6, ~3×10−5, ~0.03 and ~0.30–0.40. Results Dark-adapted abcr−/− mice and controls exhibited similar normalized near-peak amplitudes of the paired-flash-ERG-derived, weak-flash response. Response recovery following ~10−6 bleaching exhibited an average exponential time constant of 319, 171 and 213 ms, respectively, in the abcr−/− and the two control strains. Recovery time constants determined for ~3×10−5 bleaching did not differ significantly among strains. However, those determined for the ~0.03 bleach indicated significantly faster recovery in abcr−/− (2.34 ± 0.74 min) than in the controls (5.36 ± 2.20 min, and 5.92 ± 2.44 min). Following ~0.30–0.40 bleaching, the initial recovery in the abcr−/− was on average faster than in controls. Conclusions By comparison with controls, abcr−/− mice exhibit faster rod recovery following a bleach of ~0.03. The data suggest that ABCR in normal rods may directly or indirectly prolong all-trans retinal clearance from the disk lumen over a significant bleaching range, and that the essential function of ABCR may be to promote the clearance of residual amounts of all-trans retinal that remain in the disks long after bleaching. PMID:18263807

In-office tooth bleaching with 38% hydrogen peroxide promotes moderate/severe pulp inflammation and production of ll-1β, TNF-β, GPX, FGF-2 and osteocalcin in rats

PubMed Central

2018-01-01

Abstract Objectives: To study the intensity of inflammatory infiltrate and production of interleukin-1β (ll-1β), tumor necrosis factor-β (TNF-β), fibroblast growth factor-2 (FGF-2), glutathione peroxidase (GPX), and osteocalcin in response to in-office tooth bleaching in rats. Material and Methods: Twenty male Wistar rats were randomized into four groups (n=5) according to the received treatment (tooth bleaching or no treatment - control) and the period of euthanasia after treatment (24 h or 10 days). We performed tooth bleaching using a 38% hydrogen peroxide gel on maxillary and mandibular incisors. After euthanasia, incisors (20 per group) were processed for histological analysis, immunohistochemistry staining of ll-1β, TNF-β, FGF-2 and GPX and osteocalcin by immunofluorescence. We analyzed data using the Mann-Whitney and Kruskal-Wallis/Dunn tests (p<0.05). Results: The bleached groups presented statistically significant differences regarding the pulp inflammation stage compared with the control groups. Bleached teeth showed moderate/severe inflammatory infiltrate and control groups presented absent inflammatory cells or a negligible number of mononuclear cells (p<0.001) at two times (24 h and 10 days). There was strong staining for ll-1β, TNF-β, and GPX in bleached groups at 24 h and strong staining for ll-1β, TNF-β, GPX and FGF-2 at 10 days. After 10 days of tooth bleaching, the bleached group showed a statistically superior amount of osteocalcin than the other groups (p<0.01). Conclusions: Tooth bleaching with 38% hydrogen peroxide causes severe pulp inflammation, but characteristics of tissue repair after 10 days.

BioPCD - A Language for GUI Development Requiring a Minimal Skill Set.

PubMed

Alvare, Graham Gm; Roche-Lima, Abiel; Fristensky, Brian

2012-11-01

BioPCD is a new language whose purpose is to simplify the creation of Graphical User Interfaces (GUIs) by biologists with minimal programming skills. The first step in developing BioPCD was to create a minimal superset of the language referred to as PCD (Pythonesque Command Description). PCD defines the core of terminals and high-level nonterminals required to describe data of almost any type. BioPCD adds to PCD the constructs necessary to describe GUI components and the syntax for executing system commands. BioPCD is implemented using JavaCC to convert the grammar into code. BioPCD is designed to be terse and readable and simple enough to be learned by copying and modifying existing BioPCD files. We demonstrate that BioPCD can easily be used to generate GUIs for existing command line programs. Although BioPCD was designed to make it easier to run bioinformatics programs, it could be used in any domain in which many useful command line programs exist that do not have GUI interfaces.

Spatial and temporal patterns of mass bleaching of corals in the Anthropocene.

PubMed

Hughes, Terry P; Anderson, Kristen D; Connolly, Sean R; Heron, Scott F; Kerry, James T; Lough, Janice M; Baird, Andrew H; Baum, Julia K; Berumen, Michael L; Bridge, Tom C; Claar, Danielle C; Eakin, C Mark; Gilmour, James P; Graham, Nicholas A J; Harrison, Hugo; Hobbs, Jean-Paul A; Hoey, Andrew S; Hoogenboom, Mia; Lowe, Ryan J; McCulloch, Malcolm T; Pandolfi, John M; Pratchett, Morgan; Schoepf, Verena; Torda, Gergely; Wilson, Shaun K

2018-01-05

Tropical reef systems are transitioning to a new era in which the interval between recurrent bouts of coral bleaching is too short for a full recovery of mature assemblages. We analyzed bleaching records at 100 globally distributed reef locations from 1980 to 2016. The median return time between pairs of severe bleaching events has diminished steadily since 1980 and is now only 6 years. As global warming has progressed, tropical sea surface temperatures are warmer now during current La Niña conditions than they were during El Niño events three decades ago. Consequently, as we transition to the Anthropocene, coral bleaching is occurring more frequently in all El Niño-Southern Oscillation phases, increasing the likelihood of annual bleaching in the coming decades. Copyright © 2018, American Association for the Advancement of Science.

Changes in surface morphology and mineralization level of human enamel following in-office bleaching with 35% hydrogen peroxide and light irradiation.

PubMed

Berger, Sandrine Bittencourt; Cavalli, Vanessa; Ambrosano, Glaucia Maria Bovi; Giannini, Marcelo

2010-01-01

The objective of this study was to evaluate the alterations on surface morphology and mineral loss of human enamel following in-office bleaching with 35% hydrogen peroxide and light irradiation. Dental enamel samples were obtained from human third molars and randomly divided into 10 groups (n = 10). The control group remained untreated. Bleached groups were treated with one of three whitening products. Bleaching was performed in a single session, during which bleaching gel was applied to the enamel surface three times for 10 minutes each time. During treatment, the bleaching agents were either irradiated by a halogen light or an LED/diode laser or were not irradiated at all. Microhardness testing was performed with a Knoop indentor and the surface morphologic observations were carried out by scanning electron microscopy (SEM). Cross-sectional microhardness (CSMH) and polarized light microscopy (PLM) were used to measure the depth of demineralization. The results revealed a significant decrease in surface microhardness values and changes to the enamel morphology after bleaching. CSMH and PLM showed that bleached enamel presented lower volume percentage of mineral up to 40 micrometers from the enamel surface and demineralization areas located in the subsuperficial region of enamel, respectively. It was concluded that 35% hydrogen peroxide can alter the surface morphology and the mineralization level of the dental enamel surface and sub-surface regardless of what type of bleaching light is used.

[Effect of bleaching agents on the color of indirect and direct composite resins].

PubMed

Xing, Wenzhong; Jiang, Tao; Chen, Xiaodong; Wang, Yining

2014-09-01

To evaluate the effect of bleaching agents on the color of indirect and direct composite resins. Five resin composite materials were tested in this in vitro study. The five composites were as follow: two indirect composite resins (Adoro SR, Ceramage) and three direct composite resins (Filtek Z350, Clearfil Majesty Esthetic, and Gradia Direct Anterior). For each material, twenty disk-shaped specimens were prepared and randomly divided into five groups according to the color parameters of specimens before bleaching treatment. The composite resin specimens were treated by one of five sample solutions which were at-home bleaching agents (10% and 15% carbarmide peroxide), in- office bleaching agents (38% H(2)O(2) and 35%H(2)O(2)) and deionized water (control group). The color parameters of specimens were measured by spectrophotometer at baseline and after bleaching treatments. The color differences (ΔE values) between baseline and post-treatments were calculated. The data of color differences were evaluated statistically using two-way analysis with a significance level of 0.05. The color changes of the resin composites were less than 2.0 after bleaching agent treatment, therefore were not perceptible. Slight increase of L(*) values and decrease of C(*)ab values in color parameters of specimens were observed. There were statistically significant differences in ΔE values for different bleaching treatments and resin materials (P = 0.001). The bleaching agents did not affect the color of indirect and direct composite resins tested.

Whole transcriptome analysis reveals changes in expression of immune-related genes during and after bleaching in a reef-building coral.

PubMed

Pinzón, Jorge H; Kamel, Bishoy; Burge, Colleen A; Harvell, C Drew; Medina, Mónica; Weil, Ernesto; Mydlarz, Laura D

2015-04-01

Climate change is negatively affecting the stability of natural ecosystems, especially coral reefs. The dissociation of the symbiosis between reef-building corals and their algal symbiont, or coral bleaching, has been linked to increased sea surface temperatures. Coral bleaching has significant impacts on corals, including an increase in disease outbreaks that can permanently change the entire reef ecosystem. Yet, little is known about the impacts of coral bleaching on the coral immune system. In this study, whole transcriptome analysis of the coral holobiont and each of the associate components (i.e. coral host, algal symbiont and other associated microorganisms) was used to determine changes in gene expression in corals affected by a natural bleaching event as well as during the recovery phase. The main findings include evidence that the coral holobiont and the coral host have different responses to bleaching, and the host immune system appears suppressed even a year after a bleaching event. These results support the hypothesis that coral bleaching changes the expression of innate immune genes of corals, and these effects can last even after recovery of symbiont populations. Research on the role of immunity on coral's resistance to stressors can help make informed predictions on the future of corals and coral reefs.

Temporary refugia for coral reefs in a warming world

NASA Astrophysics Data System (ADS)

van Hooidonk, R.; Maynard, J. A.; Planes, S.

2013-05-01

Climate-change impacts on coral reefs are expected to include temperature-induced spatially extensive bleaching events. Bleaching causes mortality when temperature stress persists but exposure to bleaching conditions is not expected to be spatially uniform at the regional or global scale. Here we show the first maps of global projections of bleaching conditions based on ensembles of IPCC AR5 (ref. ) models forced with the new Representative Concentration Pathways (RCPs). For the three RCPs with larger CO2 emissions (RCP 4.5, 6.0 and 8.5) the onset of annual bleaching conditions is associated with ~ 510ppm CO2 equivalent; the median year of all locations is 2040 for the fossil-fuel aggressive RCP 8.5. Spatial patterns in the onset of annual bleaching conditions are similar for each of the RCPs. For RCP 8.5, 26% of reef cells are projected to experience annual bleaching conditions more than 5 years later than the median. Some of these temporary refugia include the western Indian Ocean, Thailand, the southern Great Barrier Reef and central French Polynesia. A reduction in the growth of greenhouse-gas emissions corresponding to the difference between RCP 8.5 and 6.0 delays annual bleaching in ~ 23% of reef cells more than two decades, which might conceivably increase the potential for these reefs to cope with these changes.

Does at-home bleaching induce systemic oxidative stress in healthy subjects?

PubMed

Akbari, M; Nejat, A H; Farkhondeh, N; Mehraban Moghadam, S; Hashemy, S I; Mohammadipour, H S

2017-03-01

At-home bleaching is a technique characterized by the use of carbamide peroxide or hydrogen peroxide as a tooth-whitening agent. However, no data exist regarding systemic safety of this technique. The aim of this study was to investigate the effect of at-home bleaching on serum redox homeostasis. Twenty-nine healthy volunteers who requested tooth-whitening participated in this study. Specified bleaching trays were fabricated for the maxilla and mandible arches. Each participant was given two syringes containing 9% hydrogen peroxide gel to use for 30 min/night for 14 nights consecutively. To evaluate the redox status, the serum concentrations of malondialdehyde (MDA), total antioxidant capacity (TAC) and pro-oxidant-antioxidant balance (PAB) were measured. Blood samples were obtained in the morning prior to initiation of study and the morning after expiration of the bleaching period. The collected data were analyzed using Student's t-test with 95% confidence interval. Twenty-three subjects completed the study. MDA, PAB and TAC were significantly increased after the bleaching period (P = 0.001, 0.001 and 0.002, respectively). At-home bleaching revealed the potential to disturb oxidant-antioxidant balance and induce oxidative stress. Its clinical relevance is unfavourable and potential side-effects of at-home bleaching should be considered. © 2016 Australian Dental Association.

Whole transcriptome analysis reveals changes in expression of immune-related genes during and after bleaching in a reef-building coral

PubMed Central

Pinzón, Jorge H.; Kamel, Bishoy; Burge, Colleen A.; Harvell, C. Drew; Medina, Mónica; Weil, Ernesto; Mydlarz, Laura D.

2015-01-01

Climate change is negatively affecting the stability of natural ecosystems, especially coral reefs. The dissociation of the symbiosis between reef-building corals and their algal symbiont, or coral bleaching, has been linked to increased sea surface temperatures. Coral bleaching has significant impacts on corals, including an increase in disease outbreaks that can permanently change the entire reef ecosystem. Yet, little is known about the impacts of coral bleaching on the coral immune system. In this study, whole transcriptome analysis of the coral holobiont and each of the associate components (i.e. coral host, algal symbiont and other associated microorganisms) was used to determine changes in gene expression in corals affected by a natural bleaching event as well as during the recovery phase. The main findings include evidence that the coral holobiont and the coral host have different responses to bleaching, and the host immune system appears suppressed even a year after a bleaching event. These results support the hypothesis that coral bleaching changes the expression of innate immune genes of corals, and these effects can last even after recovery of symbiont populations. Research on the role of immunity on coral's resistance to stressors can help make informed predictions on the future of corals and coral reefs. PMID:26064625

Assessing the effects of hydrogen peroxide bleaching agent on the shear bond strength of orthodontic brackets.

PubMed

Andrighetto, Augusto Ricardo; de Leão Withers, Eduardo Henrique; Grando, Karlos Giovani; Ambrosio, Aldrieli Regina; Shimizu, Roberto Hideo; Melo, Ana Cláudia

2016-01-01

Tooth bleaching is, today, one of the most widespread cosmetic treatments in dental practice,  so it is important to determine whether it can interfere with orthodontic bonding or not. The aim of this study was to assess the in vitro effects of 35% hydrogen peroxide bleaching agent on the shear bond strength of orthodontic brackets. Forty-five upper bicuspids were divided into three groups (n = 15). In the control Group (C), the brackets were bonded without previous bleaching treatment. Group 1 (G1) was treated with 35% hydrogen peroxide bleaching agent 24 h before bracket bonding. Group 2 was also bleached, and the brackets were bonded after 30 days. The shear bond strength of the brackets was measured using an EMIC machine, and the results were analyzed by ANOVA. There were no statistically significant differences between the three groups (P > 0.05), with Group C showing a mean bond strength of 9.72 ± 2.63 MPa, G1 of 8.09 ± 2.63 MPa, and G2 of 11.15 ± 4.42 MPa. It was possible to conclude that 35% hydrogen peroxide bleaching agent does not affect the shear strength of orthodontic brackets bonded 24 h and 30 days after bleaching.

The northern limit of corals of the genus Acropora in temperate zones is determined by their resilience to cold bleaching.

PubMed

Higuchi, Tomihiko; Agostini, Sylvain; Casareto, Beatriz Estela; Suzuki, Yoshimi; Yuyama, Ikuko

2015-12-18

The distribution of corals in Japan covers a wide range of latitudes, encompassing tropical to temperate zones. However, coral communities in temperate zones contain only a small subset of species. Among the parameters that determine the distribution of corals, temperature plays an important role. We tested the resilience to cold stress of three coral species belonging to the genus Acropora in incubation experiments. Acropora pruinosa, which is the northernmost of the three species, bleached at 13 °C, but recovered once temperatures were increased. The two other species, A. hyacinthus and A. solitaryensis, which has a more southerly range than A. pruinosa, died rapidly after bleaching at 13 °C. The physiological effects of cold bleaching on the corals included decreased rates of photosynthesis, respiration, and calcification, similar to the physiological effects observed with bleaching due to high temperature stress. Contrasting hot bleaching, no increases in antioxidant enzyme activities were observed, suggesting that reactive oxygen species play a less important role in bleaching under cold stress. These results confirmed the importance of resilience to cold stress in determining the distribution and northern limits of coral species, as cold events causing coral bleaching and high mortality occur regularly in temperate zones.

Derivation of a closed form analytical expression for fluorescence recovery after photo bleaching in the case of continuous bleaching during read out

NASA Astrophysics Data System (ADS)

Endress, E.; Weigelt, S.; Reents, G.; Bayerl, T. M.

2005-01-01

Measurements of very slow diffusive processes in membranes, like the diffusion of integral membrane proteins, by fluorescence recovery after photo bleaching (FRAP) are hampered by bleaching of the probe during the read out of the fluorescence recovery. In the limit of long observation time (very slow diffusion as in the case of large membrane proteins), this bleaching may cause errors to the recovery function and thus provides error-prone diffusion coefficients. In this work we present a new approach to a two-dimensional closed form analytical solution of the reaction-diffusion equation, based on the addition of a dissipative term to the conventional diffusion equation. The calculation was done assuming (i) a Gaussian laser beam profile for bleaching the spot and (ii) that the fluorescence intensity profile emerging from the spot can be approximated by a two-dimensional Gaussian. The detection scheme derived from the analytical solution allows for diffusion measurements without the constraint of observation bleaching. Recovery curves of experimental FRAP data obtained under non-negligible read-out bleaching for native membranes (rabbit endoplasmic reticulum) on a planar solid support showed excellent agreement with the analytical solution and allowed the calculation of the lipid diffusion coefficient.

Sodium hypochlorite (dilute chlorine bleach) oral rinse in patient self-care.

PubMed

Rich, Sandra K; Slots, Jørgen

2015-01-01

Sodium hypochlorite (NaOCl), commonly known as "bleach," is widely accepted as being a safe and effective antiseptic against bacteria, fungi, and viruses. For over a century, bleach has been used to control or overcome infection in homes, hospitals, and even on battlefields, and in endodontics for disinfection of root canals. This paper reviews clinical studies on the efficacy of sodium hypochlorite oral rinse to combat dental plaque and gingival inflammation. Sodium hypochlorite is readily available as inexpensive household bleach, and we suggest that oral rinsing twice weekly with dilute bleach (0.25% sodium hypochlorite) constitutes a valuable adjunct to current methods of plaque removal.

The effect of different bleaching wavelengths on the sensitivity of Al{sub 2}O{sub 3}:C optically stimulated luminescence detectors (OSLDs) exposed to 6 MV photon beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Omotayo, Azeez A.; Cygler, Joanna E.; Sawakuchi, Gabriel O.

2012-09-15

Purpose: To determine the effect of different bleaching wavelengths on the response of Al{sub 2}O{sub 3}:C optically stimulated luminescence detectors (OSLDs) exposed to accumulated doses of 6 MV photon beams. Methods: In this study the authors used nanoDot OSLDs readout with a MicroStar reader. The authors first characterized the dose-response, fading, and OSL signal loss of OSLDs exposed to doses from 0.5 to 10 Gy. To determine the effect of different bleaching wavelengths on the OSLDs' response, the authors optically treated the OSLDs with 26 W fluorescent lamps in two modes: (i) directly under the lamps for 10, 120, andmore » 600 min and (ii) with a long-pass filter for 55, 600, and 2000 min. Changes in the OSLDs' sensitivity were determined for an irradiation-readout-bleaching-readout cycle after irradiations with 1 and 10 Gy dose fractions. Results: The OSLDs presented supralinearity for doses of 2 Gy and above. The signal loss rates for sequential readouts were (0.287 {+-} 0.007)% per readout in the reader's strong-stimulation mode, and (0.019 {+-} 0.002)% and (0.035 {+-} 0.007)% per readout for doses of 0.2 and 10 Gy, respectively, in the reader's weak-stimulation mode. Fading half-life values ranged from (0.98 {+-} 0.14) min to (1.77 {+-} 0.24) min and fading showed dose dependence for the first 10-min interval. For 10 and 55 min bleaching using modes (i) and (ii), the OSL signal increased 14% for an accumulated dose of 7 Gy (1 Gy fractions). For OSLDs exposed to 10 Gy fractions, the OSL signal increased 30% and 25% for bleaching modes (i) and (ii) and accumulated dose of 70 Gy, respectively. For 120 and 600 min bleaching using modes (i) and (ii), the OSL signal increased 2.7% and 1.5% for an accumulated dose of 7 Gy (1 Gy fractions), respectively. For 10 Gy fractions, the signal increased 14% for bleaching mode (i) (120 min bleaching) and decreased 1.3% for bleaching mode (ii) (600 min bleaching) for an accumulated dose of 70 Gy. For 600 and 2000 min bleaching using modes (i) and (ii), the signal increased 2.3% and 1.8% for an accumulated dose of 7 Gy (1 Gy fractions), respectively. For 10 Gy fractions, the signal increased 10% for mode (i) (600 min bleaching) and decreased 2.5% for mode (ii) (2000 min bleaching) for an accumulated dose of 70 Gy. Conclusions: The dose-response of nanoDot OSLDs read using the MicroStar reader presented supralinearity for doses of 2 Gy and above. The signal loss as a function of sequential readouts depended on dose. Fading also depended on dose for the first 10-min interval. For dose fractions of 1 and 10 Gy, OSLDs may be reused within 3% and 5% accuracies up to the maximum accumulated dose of 7 and 70 Gy investigated in this study, respectively. These accuracies were obtained after the OSLDs were bleached with a light source with wavelengths above about 495 nm. The authors also concluded that changes in sensitivity of OSLDs depended on bleaching time, accumulated dose, and wavelength spectrum of the bleaching source.« less

BLEACHING MECHANISM OF ORGANIC PHOTOTROPIC SUBSTANCES USED IN RUBY LASERS AS SWITCHES,

DTIC Science & Technology

The bleaching process of organic phototropic switches under the effect of ruby laser emission was examined. The effect of the atomic constants of solutions on the bleaching process is evaluated. (Author)

Local bleaching thresholds established by remote sensing techniques vary among reefs with deviating bleaching patterns during the 2012 event in the Arabian/Persian Gulf.

PubMed

Shuail, Dawood; Wiedenmann, Jörg; D'Angelo, Cecilia; Baird, Andrew H; Pratchett, Morgan S; Riegl, Bernhard; Burt, John A; Petrov, Peter; Amos, Carl

2016-04-30

A severe bleaching event affected coral communities off the coast of Abu Dhabi, UAE in August/September, 2012. In Saadiyat and Ras Ghanada reefs ~40% of the corals showed signs of bleaching. In contrast, only 15% of the corals were affected on Delma reef. Bleaching threshold temperatures for these sites were established using remotely sensed sea surface temperature (SST) data recorded by MODIS-Aqua. The calculated threshold temperatures varied between locations (34.48 °C, 34.55 °C, 35.05 °C), resulting in site-specific deviations in the numbers of days during which these thresholds were exceeded. Hence, the less severe bleaching of Delma reef might be explained by the lower relative heat stress experienced by this coral community. However, the dominance of Porites spp. that is associated with the long-term exposure of Delma reef to elevated temperatures, as well as the more pristine setting may have additionally contributed to the higher coral bleaching threshold for this site. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

The effect of bleaching agents on the microhardness of dental aesthetic restorative materials.

PubMed

Türker, S B; Biskin, T

2002-07-01

This study investigated the effects of three home bleaching agents on the microhardness of various dental aesthetic restorative materials. The restorative materials were: feldspatic porcelain, microfilled composite resin and light-cured modified glass-ionomer cement and the bleaching agents Nite-White (16% carbamide peroxide), Opalescence (10% carbamide peroxide and carbapol jel) and Rembrandt (10% carbamide peroxide jel). A total of 90 restorative material samples were prepared 1 cm diameter and 6 mm thick and kept in distilled water for 24 h before commencing bleaching which was carried out for 8 h day-1 for 4 weeks. Microhardness measurements were then made using a Tukon tester. Statistically significant differences with respect to unbleached controls were found only for the feldspatic porcelain and microfilled composite resins (P <0.05) for Nite-White and Opalescence. All the bleaching agents decreased the microhardness of the porcelain and increased that of the light cured modified glass-ionomer cement. For the composite resin, whereas Nite-White increased its microhardness, the other bleaching agents decreased it. There were no significant differences between the bleaching agents for any of the restorative materials.

A Strategic Framework for Responding to Coral Bleaching Events in a Changing Climate

NASA Astrophysics Data System (ADS)

Maynard, J. A.; Johnson, J. E.; Marshall, P. A.; Eakin, C. M.; Goby, G.; Schuttenberg, H.; Spillman, C. M.

2009-07-01

The frequency and severity of mass coral bleaching events are predicted to increase as sea temperatures continue to warm under a global regime of rising ocean temperatures. Bleaching events can be disastrous for coral reef ecosystems and, given the number of other stressors to reefs that result from human activities, there is widespread concern about their future. This article provides a strategic framework from the Great Barrier Reef to prepare for and respond to mass bleaching events. The framework presented has two main inter-related components: an early warning system and assessment and monitoring. Both include the need to proactively and consistently communicate information on environmental conditions and the level of bleaching severity to senior decision-makers, stakeholders, and the public. Managers, being the most timely and credible source of information on bleaching events, can facilitate the implementation of strategies that can give reefs the best chance to recover from bleaching and to withstand future disturbances. The proposed framework is readily transferable to other coral reef regions, and can easily be adapted by managers to local financial, technical, and human resources.

An effective ostrich oil bleaching technique using peroxide value as an indicator.

PubMed

Palanisamy, Uma Devi; Sivanathan, Muniswaran; Radhakrishnan, Ammu Kutty; Haleagrahara, Nagaraja; Subramaniam, Thavamanithevi; Chiew, Gan Seng

2011-07-05

Ostrich oil has been used extensively in the cosmetic and pharmaceutical industries. However, rancidity causes undesirable chemical changes in flavour, colour, odour and nutritional value. Bleaching is an important process in refining ostrich oil. Bleaching refers to the removal of certain minor constituents (colour pigments, free fatty acid, peroxides, odour and non-fatty materials) from crude fats and oils to yield purified glycerides. There is a need to optimize the bleaching process of crude ostrich oil prior to its use for therapeutic purposes. The objective of our study was to establish an effective method to bleach ostrich oil using peroxide value as an indicator of refinement. In our study, we showed that natural earth clay was better than bentonite and acid-activated clay to bleach ostrich oil. It was also found that 1 hour incubation at a 150 °C was suitable to lower peroxide value by 90%. In addition, the nitrogen trap technique in the bleaching process was as effective as the continuous nitrogen flow technique and as such would be the recommended technique due to its cost effectiveness.

40 CFR 62.4352 - Identification of sources.

Code of Federal Regulations, 2010 CFR

2010-07-01

... (CONTINUED) APPROVAL AND PROMULGATION OF STATE PLANS FOR DESIGNATED FACILITIES AND POLLUTANTS Kentucky Total Reduced Sulfur from Existing Kraft Pulp Mills § 62.4352 Identification of sources. The plan applies to..., Ky. (b) Willamette Industries, Corrugated Medium Mill and Bleached Pulp Mill, Hawesville, Kentucky...

Bleach vs. Bacteria

MedlinePlus

... Inside Life Science > Bleach vs. Bacteria Inside Life Science View All Articles | Inside Life Science Home Page Bleach vs. Bacteria By Sharon Reynolds ... For Proteins, Form Shapes Function This Inside Life Science article also appears on LiveScience . Learn about related ...

ENAMEL SUSCEPTIBILITY TO RED WINE STAINING AFTER 35% HYDROGEN PEROXIDE BLEACHING

PubMed Central

Berger, Sandrine Bittencourt; Coelho, Alessandra Sanchez; Oliveira, Valéria Aparecida Pessatti; Cavalli, Vanessa; Giannini, Marcelo

2008-01-01

Concern has been expressed regarding the staining of enamel surface by different beverages after bleaching. This study investigated the influence of 35% hydrogen peroxide bleaching agents on enamel surface stained with wine after whitening treatments. Flat and polished bovine enamel surfaces were submitted to two commercially available 35% hydrogen peroxide bleaching agents or kept in 100% humidity, as a control group (n = 10). Specimens of all groups were immersed in red wine for 48 h at 37°C, immediately, 24 h or 1 week after treatments. All specimens were ground into powder and prepared for the spectrophotometric analysis. Data were subjected to two-way analysis of variance and Fisher's PLSD test at 5% significance level. The amount of wine pigments uptake by enamel submitted to bleaching treatments was statistically higher than that of control group, independently of the evaluation time. Results suggested that wine staining susceptibility was increased by bleaching treatments. PMID:19089218

Coral bleaching pathways under the control of regional temperature variability

NASA Astrophysics Data System (ADS)

Langlais, C. E.; Lenton, A.; Heron, S. F.; Evenhuis, C.; Sen Gupta, A.; Brown, J. N.; Kuchinke, M.

2017-11-01

Increasing sea surface temperatures (SSTs) are predicted to adversely impact coral populations worldwide through increasing thermal bleaching events. Future bleaching is unlikely to be spatially uniform. Therefore, understanding what determines regional differences will be critical for adaptation management. Here, using a cumulative heat stress metric, we show that characteristics of regional SST determine the future bleaching risk patterns. Incorporating observed information on SST variability, in assessing future bleaching risk, provides novel options for management strategies. As a consequence, the known biases in climate model variability and the uncertainties in regional warming rate across climate models are less detrimental than previously thought. We also show that the thresholds used to indicate reef viability can strongly influence a decision on what constitutes a potential refugia. Observing and understanding the drivers of regional variability, and the viability limits of coral reefs, is therefore critical for making meaningful projections of coral bleaching risk.

Aesthetic Rehabilitation of Discoloured Nonvital Anterior tooth with Carbamide Peroxide Bleaching: Case Series

PubMed Central

Badole, Gautam P; Warhadpande, Manjusha M; Bahadure, Rakesh N; Badole, Shital G

2013-01-01

Discolouration of teeth, especially the anteriores, can result in considerably cosmetic impairment in person. Combine effects of intrinsic and extrinsic colour determines the appearance of teeth. Whitening of teeth with bleaching is a more conservative therapeutic method than full crowns, veneers or composite restorations which is more invasive and expensive. Among bleaching techniques, in office bleaching with carbamide peroxide provide superior aesthetic result in short period of time with no adverse effects. This paper presents case series of tooth discolouration in non-vital tooth which was successfully bleached using 35 % carbamide peroxide. After 1 year follow up the prognosis was good with no reversal of tooth discolouration. This case report allows the better understanding of the concept of nonvital tooth bleaching with carbamide peroxide which gives a non-invasive alternative for aesthetic purpose in preserving the natural tooth structure. PMID:24551731

Climate change disables coral bleaching protection on the Great Barrier Reef.

PubMed

Ainsworth, Tracy D; Heron, Scott F; Ortiz, Juan Carlos; Mumby, Peter J; Grech, Alana; Ogawa, Daisie; Eakin, C Mark; Leggat, William

2016-04-15

Coral bleaching events threaten the sustainability of the Great Barrier Reef (GBR). Here we show that bleaching events of the past three decades have been mitigated by induced thermal tolerance of reef-building corals, and this protective mechanism is likely to be lost under near-future climate change scenarios. We show that 75% of past thermal stress events have been characterized by a temperature trajectory that subjects corals to a protective, sub-bleaching stress, before reaching temperatures that cause bleaching. Such conditions confer thermal tolerance, decreasing coral cell mortality and symbiont loss during bleaching by over 50%. We find that near-future increases in local temperature of as little as 0.5°C result in this protective mechanism being lost, which may increase the rate of degradation of the GBR. Copyright © 2016, American Association for the Advancement of Science.

Near-infrared (NIR) emitting conjugated polymers for biomedical applications (Presentation Recording)

NASA Astrophysics Data System (ADS)

Repenko, Tatjana; Kuehne, Alexander J. C.

2015-10-01

Fluorescent biomedical markers of today such as dye-infiltrated colloids, microgels and quantum dots suffer from fast bleaching, lack surface functionality (for targets or pharmaceutical agents) and potentially leach heavy metals in case of quantum dots (e.g. Cd). By contrast, conjugated polymer particles are non-cytotoxic, exhibit reduced bleaching, as the entire particle consists of fluorophore, they are hydrophobic and show high quantum yields. Consequently, conjugated polymer particles represent ideal materials for biological applications and imaging. However currently, conjugated polymer particles for biomedical imaging usually lack near-infrared (NIR) emission and are polydisperse. Fluorescent agents with emission in the NIR spectrum are interesting for biomedical applications due to their low photo-damage towards biological species and the ability of NIR radiation to penetrate deep into biological tissue.. I will present the development and synthesis of new conjugated polymers particles with fluorescence in the NIR spectral region for bio-imaging and clinical diagnosis. The particle synthesis proceeds in a one-step Pd or Ni-catalyzed dispersion polymerization of functional NIR emitters. The resulting monodisperse conjugated polymer particles are obtained as a dispersion in a non-hazardous solvent. Different sizes in the sub-micrometer range with a narrow size distribution can be produced. Furthermore biological recognition motifs can be easily attached to the conjugated polymers via thiol-yne click-chemistry providing specific tumor targeting without quenching of the fluorescence. References [1] Kuehne AJC, Gather MC, Sprakel J., Nature Commun. 2012, 3, 1088. [2] Repenko T, Fokong S, De Laporte L, Go D, Kiessling F, Lammers T, Kuehne AJC.,Chem Commun 2015, accepted.

12-month color stability of enamel, dentine, and enamel-dentine samples after bleaching.

PubMed

Wiegand, Annette; Drebenstedt, Steffi; Roos, Malgorzata; Magalhães, Ana Carolina; Attin, Thomas

2008-12-01

The study aimed to quantify the color regression of enamel (E), dentine (D), and combined enamel-dentine (ED) of differently bleached ED specimens over a period of 12 months in vitro. Two ED samples were obtained from the labial surfaces of bovine teeth and prepared to a standardized thickness with the enamel and dentine layer each 1 mm. The ED samples were distributed on four groups (each n = 80), in which the different bleaching products were applied on enamel (1, Whitestrips; 2, Illuminé 15%; 3, Opalescence Xtra Boost) or dentine surfaces (4, mixture of sodium perborate/distilled water). Eighty ED samples were not bleached (control). Color (L*a*b*) of ED was assessed at baseline, subsequently after bleaching and at 3, 6, and 12 months of storage after bleaching (each 20 samples/group). E and D samples were prepared by removing the dentine or enamel layer of ED samples to allow for separate color analysis. Bleaching resulted in a significant color change (Delta E) of ED specimens. Within the observation period, Delta L but not Delta b declined to baseline. L* values of E and D samples also declined and were not significantly different from control samples after 12 months, while b* values did not decrease to baseline. Generally, no differences between the bleaching agents could be observed. Color change of enamel, dentine, and combined ED of in vitro bleached tooth samples is not stable over time with regard to lightness. However, yellowness did not return to baseline within 1 year.

Outbreak and persistence of opportunistic symbiotic dinoflagellates during the 2005 Caribbean mass coral 'bleaching' event.

PubMed

LaJeunesse, Todd C; Smith, Robin T; Finney, Jennifer; Oxenford, Hazel

2009-12-07

Reef corals are sentinels for the adverse effects of rapid global warming on the planet's ecosystems. Warming sea surface temperatures have led to frequent episodes of bleaching and mortality among corals that depend on endosymbiotic micro-algae (Symbiodinium) for their survival. However, our understanding of the ecological and evolutionary response of corals to episodes of thermal stress remains inadequate. For the first time, we describe how the symbioses of major reef-building species in the Caribbean respond to severe thermal stress before, during and after a severe bleaching event. Evidence suggests that background populations of Symbiodinium trenchi (D1a) increased in prevalence and abundance, especially among corals that exhibited high sensitivity to stress. Contrary to previous hypotheses, which posit that a change in symbiont occurs subsequent to bleaching, S. trenchi increased in the weeks leading up to and during the bleaching episode and disproportionately dominated colonies that did not bleach. During the bleaching event, approximately 20 per cent of colonies surveyed harboured this symbiont at high densities (calculated at less than 1.0% only months before bleaching began). However, competitive displacement by homologous symbionts significantly reduced S. trenchi's prevalence and dominance among colonies after a 2-year period following the bleaching event. While the extended duration of thermal stress in 2005 provided an ecological opportunity for a rare host-generalist symbiont, it remains unclear to what extent the rise and fall of S. trenchi was of ecological benefit or whether its increased prevalence was an indicator of weakening coral health.

Influence of Bleaching Agents on Color and Translucency of Aged Resin Composites.

PubMed

Lago, Maristela; Mozzaquatro, Lisandra R; Rodrigues, Camila; Kaizer, Marina R; Mallmann, André; Jacques, Letícia B

2017-09-01

Evaluate the influence of two bleaching agents (16% carbamide peroxide-CP and 35% hydrogen peroxide-HP) on color and translucency of one resin composite (Filtek Z350 XT) in two opacities (enamel and dentin) previously aged in deionized water or red wine. Sixty specimens of each material were divided in two groups (n = 30): aged in water or red wine for 14 days. Then the specimens were divided in three subgroups (n = 10): control/no treatment, treated with 16% carbamide peroxide (Mix Night), treated with 35% hydrogen peroxide (Mix One). Color readings were performed 24 hours after polishing (baseline); after the 14 days of aging; and after bleaching treatment. Color coordinates CIE L*a*b* were measured using a spectrophotometer (SP60 X-Rite). Color change (CIEDE2000) and translucency parameter were calculated. Data were analyzed with repeated measures two-way ANOVA, and Student-Newman-Keuls tests (5%). Bleaching decreased color change in stained resin composites (aged in red wine), whereas increased it in non-stained enamel resin composites (aged in water). CP had better bleaching results with stained resin composites than HP. Translucency of non-stained dentin resin composite decreased with aging, but did not change with bleaching. For stained resin composites, aging caused reduced translucency, whereas bleaching increased it. Effective bleaching of discolored resin composites aged in an acidic and alcoholic media rich in staining agents was achieved, improving color and translucency. Carbamide peroxide showed better performance than hydrogen peroxide for the bleaching of stained resin composites. (J Esthet Restor Dent 29:368-377, 2017). © 2016 Wiley Periodicals, Inc.

Effect of At-home and In-office Bleaching on Marginal Microleakage in Composite Resin Restorations using Two Adhesive Systems.

PubMed

Klein, Celso A; da Silva, Douglas; Reston, Eduardo G; Borghetti, Diana Lb; Zimmer, Roberto

2018-03-01

The aim of this study is to assess marginal microleakage of cervical cavities restored with composite resins and two different adhesive techniques subjected to at-home and in-office bleaching. In this randomized, blind laboratory experiment, 60 bovine teeth recently extracted were collected and divided into six groups (n = 10 each group). The teeth received cervical cavity preparations (2 mm × 3 mm × 1 mm) with enamel margins. Two different adhesive systems were used (Single Bond 2 and Clearfil SE Bond), in addition to composite resin (Z250). Restored teeth received two different bleaching gels (Opalescence PF and Opalescence Boost). Teeth were thermo-cycled and analyzed under confocal laser scanning microscopy. No significant differences were observed (p > 0.05) in microleakage scores between the two groups not subjected to bleaching nor between the four groups that received bleaching treatment (p > 0.05), regardless of the gel and adhesive system employed. However, when comparing nonbleached with bleached teeth, those not subjected to bleaching showed statistically lower marginal microleakage scores (p < 0.05). Data were statistically analyzed using the Kruskal-Wallis test followed by Student-Newman-Keuls post hoc test, with significance set at 5%. Marginal microleakage in composite resin restorations is influenced by the action of bleaching agents used both at-home and in-office, regardless of the adhesive system employed (total-etch or self-etch). Both at-home and in-office bleaching agents have an influence on the adhesive interface of resin restorations, producing changes and inducing marginal leakage.

Effect of different bleaching strategies on microhardness of a silorane-based composite resin.

PubMed

Bahari, Mahmoud; Savadi Oskoee, Siavash; Mohammadi, Narmin; Ebrahimi Chaharom, Mohammad Esmaeel; Godrati, Mostafa; Savadi Oskoee, Ayda

2016-01-01

Background. Dentists' awareness of the effects of bleaching agents on the surface and mechanical properties of restorative materials is of utmost importance. Therefore, this in vitro study was undertaken to investigate the effects of different bleaching strategies on the microhardness of a silorane-based composite resin. Methods. Eighty samples of a silorane-based composite resin (measuring 4 mm in diameter and 2 mm in thickness) were prepared within acrylic molds. The samples were polished and randomly assigned to 4 groups (n=20). Group 1 (controls) were stored in distilled water for 2 weeks. The samples in group 2 underwent a bleaching procedure with 15% carbamide peroxide for two weeks two hours daily. The samples in group 3 were bleached with 35% hydrogen peroxide twice 5 days apart for 30 minutes each time. The samples in group 4 underwent a bleaching procedure with light-activated 35% hydrogen peroxide under LED light once for 40 minutes. Then the microhardness of the samples was determined using Vickers method. Data were analyzed with one-way ANOVA and post hoc Tukey tests (P < 0.05). Results. All the bleaching agents significantly decreased microhardness compared to the control group (P < 0.05). In addition, there were significant differences in microhardness between groups 2 and 4 (P = 0.001) and between groups 3 and 4 (P<0.001). However, no significant differences were detected in microhardness between groups 2 and 3 (P > 0.05). Conclusion. Bleaching agents decreased microhardness of silorane-based composite resin restorations, the magnitude of which depending on the bleaching strategy used.

In vivo Microscale Measurements of Light and Photosynthesis during Coral Bleaching: Evidence for the Optical Feedback Loop?

PubMed Central

Wangpraseurt, Daniel; Holm, Jacob B.; Larkum, Anthony W. D.; Pernice, Mathieu; Ralph, Peter J.; Suggett, David J.; Kühl, Michael

2017-01-01

Climate change-related coral bleaching, i.e., the visible loss of zooxanthellae from the coral host, is increasing in frequency and extent and presents a major threat to coral reefs globally. Coral bleaching has been proposed to involve accelerating light stress of their microalgal endosymbionts via a positive feedback loop of photodamage, symbiont expulsion and excess in vivo light exposure. To test this hypothesis, we used light and O2 microsensors to characterize in vivo light exposure and photosynthesis of Symbiodinium during a thermal stress experiment. We created tissue areas with different densities of Symbiodinium cells in order to understand the optical properties and light microenvironment of corals during bleaching. Our results showed that in bleached Pocillopora damicornis corals, Symbiodinium light exposure was up to fivefold enhanced relative to healthy corals, and the relationship between symbiont loss and light enhancement was well-described by a power-law function. Cell-specific rates of Symbiodinium gross photosynthesis and light respiration were enhanced in bleached P. damicornis compared to healthy corals, while areal rates of net photosynthesis decreased. Symbiodinium light exposure in Favites sp. revealed the presence of low light microniches in bleached coral tissues, suggesting that light scattering in thick coral tissues can enable photoprotection of cryptic symbionts. Our study provides evidence for the acceleration of in vivo light exposure during coral bleaching but this optical feedback mechanism differs between coral hosts. Enhanced photosynthesis in relation to accelerating light exposure shows that coral microscale optics exerts a key role on coral photophysiology and the subsequent degree of radiative stress during coral bleaching. PMID:28174567

Effect of resin infiltration on the color and microhardness of bleached white-spot lesions in bovine enamel (an in vitro study).

PubMed

Horuztepe, Sidika Aynur; Baseren, Meserret

2017-09-01

The aim of this study was to investigate both the effect of resin infiltration on the color and microhardness of white spot lesions (WSLs) that treated with bleaching and to analyze the penetration of the infiltrant. In each of 135 bovine enamel specimens, WSLs were produced. The samples were then randomly divided into three groups (n = 45): group I, bleached; group II, resin-infiltrated; group III, bleached and resin-infiltrated. The specimens were subjected to a pH-cycling regime for four weeks. The color and microhardness were measured at the baseline, after production of WSLs, after the treatments. The color alteration (ΔE*) and the percentage of surface microhardness recovery (SMHR) were calculated. The penetration of the infiltrant was evaluated by scanning electron microscopy. Results were analyzed with analysis of variance, Shapiro-Wilk, Tukey's, Kruskal-Wallis and Conover-Dunn tests (P = .05). The SMHR% in resin infiltration groups was significantly higher than that of the bleached group only (P < .05). Bleaching treatment prior to resin infiltration produced no significant change in the microhardness (P > .05). Using a bleaching treatment prior to resin infiltration produced significant color alteration (P < .05). The penetration of the resin infiltrant was deepest in-group II. The resin infiltration enhanced the microhardness of the WSLs regardless of whether or not a bleaching treatment was used. Using a bleaching treatment before resin infiltration resulted in color alteration, and it was also found to negatively influence the penetration of the infiltrant. © 2017 Wiley Periodicals, Inc.

The effect of baking soda when applied to bleached enamel prior to restorative treatment.

PubMed

Tostes, Bhenya Ottoni; Mondelli, Rafael Francisco Lia; Lima-Arsati, Ynara Bosco de Oliveira; Rodrigues, Jose Augusto; Costa, Leonardo Cesar

2013-08-01

This in vitro study evaluated the effect of 10% baking soda solution and sodium bicarbonate powder (applied with jets) when applied to bleached enamel prior to restorative treatment. The surfaces of 40 bovine incisors were flattened and divided into 5 groups (n = 8): Group B (bleached and restored, negative control), Group W (bleached, stored in distilled water for 7 days, and restored), Group BSJ (bleached, abraded with baking soda jet for 1 min, and restored), Group BSS (bleached, application of 10% baking soda solution for 5 min, and restored), and Group R (restored, without bleaching, positive control). The samples were bleached in 1 session with 3 applications of 35% HP-based gel and activated with a LED appliance for 9 min each. Resin composite cylinders (2 mm height and 0.8 mm diameter) were made on the enamel surface after the acid etching and a conventional 1-step single vial adhesive application was performed. After storage in distilled water (37 ± 1°C, 24 hr), the microshear bond test was performed (1 mm/min). ANOVA and Tukey tests were applied to compare the results. The mean results of these tests showed that Groups W, BBS, and R were not statistically different. These groups also indicated a higher bond strength when compared with Groups B and BSJ. The application of 10% baking soda solution for 5 min may be an alternative pre-restorative treatment for bleached enamel, but further studies are needed to consider whether or not this treatment may be effectively used in clinical practice.

Effects of at-home and in-office bleaching agents on the shear bond strength of metal, ceramic, and composite brackets to enamel.

PubMed

Rahul, M; Kumar, P Anil; Nair, Amal S; Mathew, Shino; Amaladas, Antony Shijoy; Ommen, Anna

2017-01-01

This study aimed to evaluate the effects of at-home and in-office bleaching on the shear bond strength (SBS) of metal, ceramic, and composite orthodontic brackets and to compare their SBSs. A total of 96 human lower premolar teeth were used for this study. Six teeth were used for scanning electron microscopic study while the remaining ninety were divided into three equal groups. Each group was further subdivided into three subgroups with ten samples each. Three protocols were used. In the at-home bleaching group (n = 30), opalescence non-PF (potassium nitrate and fluoride) bleaching agent (10% carbamide peroxide) was applied onto the teeth daily for 14 days and left for 8 h each day. Teeth in the in-office group (n = 30) were treated twice in consecutive days with Opalescence boost PF (40% hydrogen peroxide). After bleaching, the specimens were stored in distilled water for 1 day before bonding. SBS testing was performed on all teeth using Instron universal testing machine. Analysis of variance indicated a significant difference (P < 0.005) among the groups. Maximum SBS was shown by ceramic brackets in control group (Ib) and minimum was shown by composite brackets of in-office bleached group (IIIc). The results showed that at-home bleaching did not affect the SBS significantly whereas in-office bleaching reduced SBS of metal, ceramic, and composite brackets significantly. It is preferable to use metal or ceramic brackets than composite brackets for bonding 24 h after bleaching.

The effect of enamel bleaching on the shear bond strengths of metal and ceramic brackets.

PubMed

Oztaş, E; Bağdelen, G; Kiliçoğlu, H; Ulukapi, H; Aydin, I

2012-04-01

The aim of this study was to evaluate the effects of bleaching and delayed bonding on the shear bond strengths of metal and ceramic brackets bonded with light and chemically cure composite resin to human enamel. One hundred and twenty extracted human premolar teeth were randomly divided into three groups of 40 each. The first two groups were bleached with 20 per cent carbamide peroxide (CP) at-home bleaching agent. No bleaching procedures were applied to the third group and served as control. The first two and control groups were divided into equal subgroups according to different adhesive-bracket combinations. Specimens in group 1 (n = 40) were bonded 24 hours after bleaching process was completed while the specimens in group 2 (n = 40) were bonded 14 days after. The specimens in all groups were debonded with a Universal testing machine while the modified adhesive remnant index was used to evaluate fracture properties. No statistically significant differences were found between the shear bond strengths of metal and ceramic brackets bonded to bleached enamel after 24 hours, 14 days, and unbleached enamel with light or chemical cure adhesives (P > 0.05). The mode of failure was mostly at the bracket/adhesive interface and cohesive failures within the resin were also observed. Our findings indicated that at-home bleaching agents that contain 20 per cent CP did not significantly affect the shear bond strength of metal and ceramic orthodontic brackets to enamel when bonding is performed 24 hours or 14 days after bleaching.

In vivo Microscale Measurements of Light and Photosynthesis during Coral Bleaching: Evidence for the Optical Feedback Loop?

PubMed

Wangpraseurt, Daniel; Holm, Jacob B; Larkum, Anthony W D; Pernice, Mathieu; Ralph, Peter J; Suggett, David J; Kühl, Michael

2017-01-01

Climate change-related coral bleaching, i.e., the visible loss of zooxanthellae from the coral host, is increasing in frequency and extent and presents a major threat to coral reefs globally. Coral bleaching has been proposed to involve accelerating light stress of their microalgal endosymbionts via a positive feedback loop of photodamage, symbiont expulsion and excess in vivo light exposure. To test this hypothesis, we used light and O 2 microsensors to characterize in vivo light exposure and photosynthesis of Symbiodinium during a thermal stress experiment. We created tissue areas with different densities of Symbiodinium cells in order to understand the optical properties and light microenvironment of corals during bleaching. Our results showed that in bleached Pocillopora damicornis corals, Symbiodinium light exposure was up to fivefold enhanced relative to healthy corals, and the relationship between symbiont loss and light enhancement was well-described by a power-law function. Cell-specific rates of Symbiodinium gross photosynthesis and light respiration were enhanced in bleached P. damicornis compared to healthy corals, while areal rates of net photosynthesis decreased. Symbiodinium light exposure in Favites sp. revealed the presence of low light microniches in bleached coral tissues, suggesting that light scattering in thick coral tissues can enable photoprotection of cryptic symbionts. Our study provides evidence for the acceleration of in vivo light exposure during coral bleaching but this optical feedback mechanism differs between coral hosts. Enhanced photosynthesis in relation to accelerating light exposure shows that coral microscale optics exerts a key role on coral photophysiology and the subsequent degree of radiative stress during coral bleaching.

Is bleach-sedimented smear microscopy an alternative to direct microscopy under programme conditions in India?

PubMed Central

Vishnu, P. H.; Bansal, A.; Satyanarayana, S.; Alavadi, U.; Ohri, B. S.; Shrinivas, M. S. Rao; Desikan, P.; Jaju, J.; Rao, V. G.; Moonan, P. K.

2013-01-01

This cross-sectional multi-centric study compared the yield of and potential benefit for detecting smear-positive pulmonary tuberculosis (PTB) by bleach sedimentation (2% sodium-hypochlorite) versus direct microscopy under programme conditions in India. Among 3168 PTB suspects, 684 (21.6%) were detected by bleach sedimentation vs. 625 (19.7%) by direct microscopy, with a proportional overall agreement of 96% (κ = 0.88). While 594 patients were smear-positive with both methods, 31 patients detected by direct microscopy were missed and an additional 90 patients were detected by bleach sedimentation. Overall, bleach sedimentation increased the yield of smear-positive TB detection; however; it also increased the time to results. PMID:26392991

Effect of 10% sodium ascorbate on the calcium: Phosphorus ratio of enamel bleached with 35% hydrogen peroxide: an in vitro quantitative energy-dispersive X-ray analysis.

PubMed

Poorni, Saravanan; Kumar, R Anil; Shankar, P; Indira, Rajamani; Ramachandran, S

2010-10-01

The study assessed quantitatively the calcium and phosphorous loss from the enamel surface following bleaching with 35% hydrogen peroxide and reversal with 10% sodium ascorbate using energy-dispersive X-ray analysis (EDAX). Eight non-carious, freshly extracted human permanent maxillary central incisors without any visible defects were used. Each specimen was bleached with 35% hydrogen peroxide activated by light and reversed with sodium ascorbate antioxidant gel. The calcium and phosphorous content in weight percent of sound, bleached and reversed enamel was acquired using EDAX. The Ca/P ratio was calculated from the obtained data. One-way ANOVA followed by Post Hoc Tukey test was used for comparing the Ca/P ratio of sound, bleached and reversed enamel. All the samples subjected to bleaching using 35% hydrogen peroxide showed a statistically significant decrease in the Ca/P ratio as compared with samples in which no bleaching procedure was performed (P-value < 0.01). The striking finding was that there was a significant increase in the Ca/P ratio on application of sodium ascorbate antioxidant gel when compared with the bleached enamel (P-value < 0.01). The authors concluded that 35% hydrogen peroxide causes a significant decrease in the Ca/P ratio. This decrease in the Ca/P ratio can be restored by the application of 10% sodium ascorbate antioxidant gel.

Inhibition of photosynthetic CO₂ fixation in the coral Pocillopora damicornis and its relationship to thermal bleaching.

PubMed

Hill, Ross; Szabó, Milán; ur Rehman, Ateeq; Vass, Imre; Ralph, Peter J; Larkum, Anthony W D

2014-06-15

Two inhibitors of the Calvin-Benson cycle [glycolaldehyde (GA) and potassium cyanide (KCN)] were used in cultured Symbiodinium cells and in nubbins of the coral Pocillopora damicornis to test the hypothesis that inhibition of the Calvin-Benson cycle triggers coral bleaching. Inhibitor concentration range-finding trials aimed to determine the appropriate concentration to generate inhibition of the Calvin-Benson cycle, but avoid other metabolic impacts to the symbiont and the animal host. Both 3 mmol l(-1) GA and 20 μmol l(-1) KCN caused minimal inhibition of host respiration, but did induce photosynthetic impairment, measured by a loss of photosystem II function and oxygen production. GA did not affect the severity of bleaching, nor induce bleaching in the absence of thermal stress, suggesting inhibition of the Calvin-Benson cycle by GA does not initiate bleaching in P. damicornis. In contrast, KCN did activate a bleaching response through symbiont expulsion, which occurred in the presence and absence of thermal stress. While KCN is an inhibitor of the Calvin-Benson cycle, it also promotes reactive oxygen species formation, and it is likely that this was the principal agent in the coral bleaching process. These findings do not support the hypothesis that temperature-induced inhibition of the Calvin-Benson cycle alone induces coral bleaching. © 2014. Published by The Company of Biologists Ltd.

Comparison of two low sensitivity whiteners.

PubMed

Callan, Richard S; Browning, William D; Downey, Mary C; Brackett, Martha G

2008-02-01

To evaluate two commercially available doctor-supplied, patient-applied, bleaching systems for their ability to whiten the maxillary anterior teeth while at the same time not causing sensitivity. 46 participants were randomly assigned to one of two groups: One group received Rembrandt Xtra-Comfort and the other group Nite White Excel 2Z. Bleaching stents were fabricated and the bleaching systems were used following manufacturers' instructions. Participants recorded tray use and any sensitivity on a daily basis. Participants bleached for 2 weeks followed by 2 weeks of no bleaching. Color was evaluated at the first, second and fourth week following the initial delivery of bleaching trays. Color change was measured using the Vita Classic Shade Guide arranged by value. As a group, participants in the NW2Z group bleached for 302 days with a total of 48 days (16%) of sensitivity recorded. The Rembrandt Xtra Comfort group bleached for 313 total days with 97 days (31%) of sensitivity recorded. The difference in sensitivity between the two products proved to be statistically significant (Chi-square analysis, P < or = 0.0001). The median shade change for both products following 2 weeks of active treatment was six tabs. At the 4-week evaluation, the median shade change was 5.5 and 6.0 tabs respectively for Rembrandt and Nite White. There was no statistical difference between the products in respect to shade change.

Effect of three nanobiomaterials on the surface roughness of bleached enamel

PubMed Central

Khoroushi, Maryam; Shirban, Farinaz; Doustfateme, Samaneh; Kaveh, Sara

2015-01-01

Background: The ever-increasing demand for enhanced esthetic appearance has resulted in significant developments in bleaching products. However, the enamel surface roughness (SR) might be negatively affected by bleaching agents. This in vitro study was undertaken to compare the effects of three nanobiomaterials on the enamel SR subsequent to bleaching. Materials and Methods: The crowns of six extracted intact nonerupted human third molars were sectioned. Five dental blocks measuring 2 mm × 3 mm × 4 mm were prepared from each tooth and placed in colorless translucent acrylic resin. The enamel areas from all the specimens were divided into five groups (n = 6): Group 1 did not undergo any bleaching procedures; Group 2 was bleached with a 40% hydrogen peroxide (HP) gel; Groups 3, 4, and 5 were bleached with a 40% HP gel modified by bioactive glass (BAG), amorphous calcium phosphate, and hydroxyapatite, respectively. The enamel SR was evaluated before and after treatment by atomic force microscopy. The data were analyzed by Kruskal–Wallis and Mann–Whitney tests. Results: SR increased significantly in the HP group. SR decreased significantly in the HP gel modified by BAG group as compared to other groups. Conclusions: Within the limitations of this study, incorporation of each one of the three test biomaterials proved effective in decreasing enamel SR subsequent to in-office bleaching technique. PMID:26681849

Laser Teeth Bleaching: Evaluation of Eventual Side Effects on Enamel and the Pulp and the Efficiency In Vitro and In Vivo

PubMed Central

De Moor, Roeland Jozef Gentil; Meire, Maarten August; De Coster, Peter Jozef

2015-01-01

Light and heat increase the reactivity of hydrogen peroxide. There is no evidence that light activation (power bleaching with high-intensity light) results in a more effective bleaching with a longer lasting effect with high concentrated hydrogen peroxide bleaching gels. Laser light differs from conventional light as it requires a laser-target interaction. The interaction takes place in the first instance in the bleaching gel. The second interaction has to be induced in the tooth, more specifically in the dentine. There is evidence that interaction exists with the bleaching gel: photothermal, photocatalytical, and photochemical interactions are described. The reactivity of the gel is increased by adding photocatalyst of photosensitizers. Direct and effective photobleaching, that is, a direct interaction with the colour molecules in the dentine, however, is only possible with the argon (488 and 415 nm) and KTP laser (532 nm). A number of risks have been described such as heat generation. Nd:YAG and especially high power diode lasers present a risk with intrapulpal temperature elevation up to 22°C. Hypersensitivity is regularly encountered, being it of temporary occurrence except for a number of diode wavelengths and the Nd:YAG. The tooth surface remains intact after laser bleaching. At present, KTP laser is the most efficient dental bleaching wavelength. PMID:25874258

A colourimetric evaluation of the effect of bacterial contamination on teeth stained with blood in vitro: Evaluation of the efficacy of two different bleaching regimes.

PubMed

Wang, S; Cathro, P; Heithersay, G; Briggs, N; Ratnayake, J; Zilm, P

2018-02-27

Tooth discolouration could occur due to bacterial contamination in traumatized teeth. Hydrogen peroxide is the commonly used bleaching agent. However, due to concerns over safety, alternative bleaching regimes such as sodium perborate (S) and thiourea-hydrogen peroxide (T) have been investigated. Apices resected and pulp extirpated 99 premolars were divided into two groups. Group 1 and 2 was injected with blood and blood/bacteria, stored anaerobically for 35 days. The two groups were treated by bleaching with water, S or T. Teeth were rebleached after 7 days. Colourimetric evaluation was assessed using digital imaging, CasMatch standardization and CIE L*a*b colour system preoperatively, 35 days of staining and 7 and 14 of bleaching. A linear mixed model with fixed effects of time, group and bleach was used to examine colour difference. Blood-stained teeth were significantly redder and darker on day 35 compared with blood/bacteria-stained teeth. After bleaching, blood-stained teeth retained significant redness compared with blood/bacteria-stained teeth using either S or T. T produced a significantly whiter shade in both the groups after 14 days. Blood-stained teeth were significantly darker and red compared with blood/bacteria-stained teeth. T bleaching regime was more effective than S. © 2018 Australian Dental Association.

Component resolved bleaching study in natural calcium fluoride using CW-OSL, LM-OSL and residual TL glow curves after bleaching.

PubMed

Angeli, Vasiliki; Polymeris, George S; Sfampa, Ioanna K; Tsirliganis, Nestor C; Kitis, George

2017-04-01

Natural calcium fluoride has been commonly used as thermoluminescence (TL) dosimeter due to its high luminescence intensity. The aim of this work includes attempting a correlation between specific TL glow curves after bleaching and components of linearly modulated optically stimulated luminescence (LM-OSL) as well as continuous wave OSL (CW-OSL). A component resolved analysis was applied to both integrated intensity of the RTL glow curves and all OSL decay curves, by using a Computerized Glow-Curve De-convolution (CGCD) procedure. All CW-OSL and LM-OSL components are correlated to the decay components of the integrated RTL signal, apart from two RTL components which cannot be directly correlated with either LM-OSL or CW-OSL component. The unique, stringent criterion for this correlation deals with the value of the decay constant λ of each bleaching component. There is only one, unique bleaching component present in all three luminescence entities which were the subject of the present study, indicating that each TL trap yields at least three different bleaching components; different TL traps can indicate bleaching components with similar values. According to the data of the present work each RTL bleaching component receives electrons from at least two peaks. The results of the present study strongly suggest that the traps that contribute to TL and OSL are the same. Copyright © 2017 Elsevier Ltd. All rights reserved.

Clinical and Spectrophotometric Evaluation of LED and Laser Activated Teeth Bleaching.

PubMed

Lo Giudice, R; Pantaleo, G; Lizio, A; Romeo, U; Castiello, G; Spagnuolo, G; Giudice, G Lo

2016-01-01

Auxiliary power sources (LED and laser) are used in in-office teeth bleaching techniques to accelerate the redox reaction of the whitening gel to increase ease of use, to improve comfort and safety, and to decrease the procedure time. The aim this study is to evaluate the efficiency of the teeth whitening procedures performed with hydrogen peroxide and carbamide peroxide, LED or Laser activated. 18 patients, affected by exogenous dyschromia, were treated with a bleaching agent composed by 35% hydrogen peroxide and 10% carbamide peroxide. They were divided into two groups: in the first group the bleaching agent was activated by a LED lamp; in the second group it was activated by a Laser diode lamp. Both groups were subjected to 3 bleaching cycle of 15' each. The chromatic evaluations were performed before and after one week from the treatment, using a chromatic scale and a spectrophotometer. The mean value of pre, post bleaching and follow-up were analyzed using a T-test, with results statistically significant for P<0,05. Results showed that the variations in brightness, chroma and hue are significantly influenced by the interaction between the whitening agent and the original colour of the teeth. Laser-activation has marginally improved the bleaching effectiveness. All patients treated with laser activation complained an increase in dental sensitivity. The use of laser-activating systems did not improve the efficacy of bleaching.

Inhibition of photosynthesis and bleaching of zooxanthellae by the coral pathogen Vibrio shiloi.

PubMed

Ben-Haim, Y; Banim, E; Kushmaro, A; Loya, Y; Rosenberg, E

1999-06-01

Vibrio shiloi is the causative agent of bleaching (loss of endosymbiotic zooxanthellae) of the coral Oculina patagonica in the Mediterranean Sea. To obtain information on the mechanism of bleaching, we examined the effect of secreted material (AK1-S) produced by V. shiloi on zooxanthellae isolated from corals. AK1-S caused a rapid inhibition of photosynthesis of the algae, as measured with a Mini-PAM fluorometer. The inhibition of photosynthesis was caused by (i) ammonia produced during the growth of V. shiloi on protein-containing media and (ii) a non-dialysable heat-resistant factor. This latter material did not inhibit photosynthesis of the algae by itself but, when added to different concentrations of NH4Cl, enhanced the inhibition approximately two- to threefold. Ammonia and the enhancer were effective to different degrees on zooxanthellae isolated from four species of coral examined. In addition to the rapid inhibition of photosynthesis, AK1-S caused bleaching (loss of pigmentation) and lysis of zooxanthellae. Bleaching was more rapid than lysis, reaching a peak (25% bleached algae) after 6 h. The factors in AK1-S responsible for bleaching and lysis were different from those responsible for the inhibition of photosynthesis, because they were heat sensitive, non-dialysable and active in the dark. Thus, the coral pathogen V. shiloi produces an array of extracellular materials that can inhibit photosynthesis, bleach and lyse zooxanthellae.

Comparison of Radicular Peroxide Leakage from four Commonly used Bleaching agents following Intracoronal Bleaching in Endodontically treated teeth - An In Vitro Study.

PubMed

Madhu, Ks; Hegde, Swaroop; Mathew, Sylvia; Lata, DA; Bhandi, Shilpa H; N, Shruthi

2013-08-01

Non vital bleaching is simple, conservative procedure for esthetic correction of discolored endodontically treated teeth. The aim of this study was to determine and compare the amount of peroxide leakage from four different bleaching agents i.e superoxol, sodium perborate, combination of superoxol & sodium perborate and carbamide peroxide during intracoronal bleaching, as the safe and effective bleaching is the need of the hour. 50 extracted maxillary centrals were selected for the study. Following standardized protocol access, cleaning and shaping by step back technique and obturation was done using guttapercha and AH plus sealer. Access was sealed with Cavit G and outer root surface was coated with wax and nail varnish. The teeth were separated into crown and root and the root portion was placed in plastic tube containing distilled water for 7days.After incubation, 3mm of gutta-percha was removed below CEJ and 2mm glass ionomer cement base was placed. Grouped into five categories based on the bleaching agent placed in pulp chamber as -group1 (control)-distilled water, group 2-sodium perborate with distilled water , group 3- 30% hydrogen peroxide ,group 4-mixture of sodium perborate and 30% hydrogen peroxide and group 5-10% carbamide peroxide gel. Peroxide leakage was measured after 24hrs using ferrothiocyanate method and optical density using spectrophotometer. Statistical analysis of the data was conducted using ANOVA and multiple comparisons within the groups was done using BONFERRONI method (Post-Hoc tests). The results showed highest peroxide penetration from 30% hydrogen peroxide followed by mixture of sodium perborate with 30% hydrogen peroxide, mixture of sodium perborate with distilled water and least penetration from 10% carbamide peroxide gel. The results were statistically significant. Radicular peroxide leakage in 10% carbamide peroxide was significantly lower than the other tested bleaching agents making it a very safe alternative for intracoronal bleaching. How to cite this article: Madhu KS, Hegde S, Mathew S, Lata DA, Bhandi SH, Shruthi N. Comparison of Radicular Peroxide Leakage from four Commonly used Bleaching agents following Intracoronal Bleaching in Endodontically treated teeth - An In Vitro Study. J Int Oral Health 2013; 5(4):49-55.

An evaluation of the effect of recent temperature variability on the prediction of coral bleaching events.

PubMed

Donner, Simon D

2011-07-01

Over the past 30 years, warm thermal disturbances have become commonplace on coral reefs worldwide. These periods of anomalous sea surface temperature (SST) can lead to coral bleaching, a breakdown of the symbiosis between the host coral and symbiotic dinoflagellates which reside in coral tissue. The onset of bleaching is typically predicted to occur when the SST exceeds a local climatological maximum by 1 degrees C for a month or more. However, recent evidence suggests that the threshold at which bleaching occurs may depend on thermal history. This study uses global SST data sets (HadISST and NOAA AVHRR) and mass coral bleaching reports (from Reefbase) to examine the effect of historical SST variability on the accuracy of bleaching prediction. Two variability-based bleaching prediction methods are developed from global analysis of seasonal and interannual SST variability. The first method employs a local bleaching threshold derived from the historical variability in maximum annual SST to account for spatial variability in past thermal disturbance frequency. The second method uses a different formula to estimate the local climatological maximum to account for the low seasonality of SST in the tropics. The new prediction methods are tested against the common globally fixed threshold method using the observed bleaching reports. The results find that estimating the bleaching threshold from local historical SST variability delivers the highest predictive power, but also a higher rate of Type I errors. The second method has the lowest predictive power globally, though regional analysis suggests that it may be applicable in equatorial regions. The historical data analysis suggests that the bleaching threshold may have appeared to be constant globally because the magnitude of interannual variability in maximum SST is similar for many of the world's coral reef ecosystems. For example, the results show that a SST anomaly of 1 degrees C is equivalent to 1.73-2.94 standard deviations of the maximum monthly SST for two-thirds of the world's coral reefs. Coral reefs in the few regions that experience anomalously high interannual SST variability like the equatorial Pacific could prove critical to understanding how coral communities acclimate or adapt to frequent and/or severe thermal disturbances.

A New Perspective: Assessing the Spatial Distribution of Coral Bleaching with Unmanned Low Altitude Remote Sensing Systems

NASA Astrophysics Data System (ADS)

Levy, J.; Franklin, E. C.; Hunter, C. L.

2016-12-01

Coral reefs are biodiversity hotspots that are vital to the function of global economic and biological processes. Coral bleaching is a significant contributor to the global decline of reefs and can impact an expansive reef area over short timescales. In order to understand the dynamics of coral bleaching and how these stress events impact reef ecosystems, it is important to conduct rapid bleaching surveys at functionally important spatial scales. Due to the inherent heterogeneity, size, and in some cases, remoteness of coral reefs, it is difficult to routinely monitor coral bleaching dynamics before, during, and after bleaching. Additionally, current in situ survey methods only collect snippets of discrete reef data over small reef areas, which are unable to accurately represent the reef as a whole. We present a new technique using small unmanned aerial systems (sUAS) as cost effective, efficient monitoring tools that target small to intermediate-scale reef dynamics to understand the spatial distribution of bleached coral colonies during the 2015 bleaching event on patch reefs in Kaneohe Bay, Oahu. Overlapping low altitude aerial images were collected at four reefs during the bleaching period and processed using Structure-from-Motion techniques to produce georeferenced and spatially accurate orthomosaics of complete reef areas. Mosaics were analyzed using manual and heuristic neural network classification schemes to identify comprehensive populations of bleached and live coral on each patch reef. We found that bleached colonies had random and clumped distributions on patch reefs in Kaneohe Bay depending on local environmental conditions. Our work demonstrates that sUAS provide a low cost, efficient platform that can rapidly and repeatedly collect high-resolution imagery (1 cm/pixel) and map large areas of shallow reef ecosystems (5 hectares). This study proves the feasibility of utilizing sUAS as a tool to collect spatially rich reef data that will provide reef scientists a new perspective on meso-scale coral reef dynamics. We envision that similar low altitude aerial surveys will be incorporated as a standard component of shallow-water reef studies, especially on reefs too dangerous or remote for in situ surveys.

Alternative bleaching methods for Cheddar cheese whey.

PubMed

Kang, E J; Smith, T J; Drake, M A

2012-07-01

Residual annatto colorant (norbixin) in fluid Cheddar cheese whey can be bleached. The 2 approved chemical bleaching agents for whey, hydrogen peroxide (HP) and benzoyl peroxide (BP), negatively impact the flavor of dried whey protein. The objective of this study was to evaluate alternative methods for bleaching liquid whey: ultraviolet radiation (UV), acid-activated bentonite (BT), and ozone (OZ). Colored Cheddar cheese whey was manufactured followed by pasteurization and fat separation. Liquid whey was subjected to one of 5 treatments: control (CT) (no bleaching; 50 °C, 1 h), HP (250 mg/kg; 50 °C, 1 h), UV (1 min exposure; 50 °C), BT (0.5% w/w; 50 °C, 1 h), or OZ (2.2g/h, 50 °C, 1 h). The treated whey was then ultrafiltered, diafiltered, and spray-dried to 80% whey protein concentrate (WPC80). The entire experiment was replicated 3 times. Color (norbixin extraction and measurement), descriptive sensory, and instrumental volatile analyses were conducted on WPC80. Norbixin elimination was 28%, 79%, 39%, and 15% for HP, BT, UV, and OZ treatments, respectively. WPC80 from bleached whey, regardless of bleaching agent, had lower sweet aromatic and cooked/milky flavors compared to unbleached CT (P < 0.05). The HP and BT WPC80 had higher fatty flavor compared to the CT WPC80 (P < 0.05), and the UV and OZ WPC80 had distinct mushroom/burnt and animal flavors. Volatile compound results were consistent with sensory results and confirmed higher relative abundances of volatile aldehydes in UV, HP, and OZ WPC80 compared to CT and BT WPC80. Based on bleaching efficacy and flavor, BT may be an alternative to chemical bleaching of fluid whey. The 2 approved chemical bleaching agents for whey, hydrogen peroxide (HP) and benzoyl peroxide (BP), negatively impact flavor of dried whey protein, and restrictions on these agents are increasing. This study evaluated 3 alternatives to chemical bleaching of fluid whey: UV radiation, ozone, and bentonite. © 2012 Institute of Food Technologists®

Hydrogen peroxide bleaching induces changes in the physical properties of dental restorative materials: Effects of study protocols.

PubMed

Yu, Hao; Zhang, Chang-Yuan; Wang, Yi-Ning; Cheng, Hui

2018-03-01

The purpose of this study was to evaluate the influence of study protocols on the effects of bleaching on the surface roughness, substance loss, flexural strength (FS), flexural modulus (FM), Weibull parameters, and color of 7 restorative materials. The test materials included 4 composite resins, 1 glass-ionomer cement, 1 dental ceramic, and 1 polyacid-modified composite. The specimens were randomly divided into 4 groups (n = 20) according to different study protocols: a bleaching group at 25°C (group 25B), a bleaching group at 37°C (group 37B), a control group at 25°C (group 25C), and a control group at 37°C (group 37C). The specimens in the bleaching group were treated with 40% hydrogen peroxide for 80 min at the respective environmental temperatures. The surface roughness, substance loss, FS, FM, and color of the specimens were measured before and after treatment. FS data were also subjected to Weibull analysis, which was used to estimate of the Weibull modulus (m) and the characteristic strength (σ 0 ). Surface roughness increased and significant color changes were observed for all tested specimens after bleaching treatment, except for the ceramic. After bleaching at 37°C, the polyacid-modified composite showed significantly reduced FS, FM, m, and σ 0 values in comparison to the control specimens stored at 37°C in whole saliva. Significant differences were also found between the 37B and 25B polyacid-modified composite groups in terms of surface roughness, FS, m, σ 0 , and color changes. Varying effects of bleaching on the physical properties of dental restorative materials were observed, and the influences of the study protocols on bleaching effects were found to be material-dependent. The influence of study protocols on the effects of bleaching on the surface roughness, flexural properties, and color of dental restorative materials are material-dependent and should be considered when evaluating the effects of bleaching on dental restorative materials. © 2017 Wiley Periodicals, Inc.

The effect of McInnes solution on enamel and the effect of Tooth mousse on bleached enamel: An in vitro study

PubMed Central

Darshan, H E; Shashikiran, N D

2008-01-01

Aims: To evaluate the effect of McInnes bleaching agent on the micro hardness of enamel before and after bleaching and to evaluate the effect of G C Tooth Mousse on the bleached enamel surface for its microhardness. Materials and Methods: McInnes bleaching solution, Casein phosphopeptide-amorphous calcium phosphate CCP-ACP (G C Tooth mousse) artificial saliva (Dept of Oral Pathology, College of Dental Sciences, Davengere), deionized water, Vickers Micro Hardness tester (Zwick/ZHV, Germany), freshly extracted teeth, cold cure acrylic, Diamond disc (Horico - PFINGST New jersey USA, KAVO- Germany), straight handpiece (kavo peca reta) and plastic moulds (6.5 × 2 mm). The purpose of this study was to evaluate and compare microhardness of the sound enamel surface by Vickers Hardness Number before and after bleaching with McInnes solution, and to evaluate the effect of casein phosphopeptide amorphous calcium phosphate (G C Tooth Mousse) on the bleached enamel surface for its microhardness. Statistical analysis: The data obtained from the test were subjected for statistical analysis and are presented as range, mean and standard deviation. P value of 0.05 or less was considered for statistical significance. The changes in microhardness at different times of assessment were analyzed using the paired ‘t’ test Results: All the samples showed decrease in the microhardness after two cycles of bleaching, though immediately after bleaching the decrease in the microhardness was not significant (P = 0.34). However, after the second cycles, it showed a significant decrease (P<0.01) in the microhardness. After application of remineralization solution (GC Tooth mousse), the samples showed a marginal increase in the microhardness (P<0.05) after seven days and a marked increase after fourteen days (P<0.001). Conclusion: McInnes bleaching agent does decrease the microhardness of enamel by causing enamel demineralization and GC Tooth mousse used in the study causes an increase in the microhardness of bleached enamel by maintaining a high gradient of calcium and phosphate ions at the enamel subsurface. PMID:20142891

Bleached chondrules: Evidence for widespread aqueous processes on the parent asteroids of ordinary chondrites

USGS Publications Warehouse

Grossman, J.N.; Alexander, C.M. O'D.; Wang, Jingyuan; Brearley, A.J.

2000-01-01

We present the first detailed study of a population of texturally distinct chondrules previously described by Kurat (1969), Christophe Michel-Levy (1976), and Skinner et al. (1989) that are sharply depleted in alkalis and Al in their outer portions. These 'bleached' chondrules, which are exclusively radial pyroxene and cryptocrystalline in texture, have porous outer zones where mesostasis has been lost. Bleached chondrules are present in all type 3 ordinary chondrites and are present in lower abundances in types 4-6. They are most abundant in the L and LL groups, apparently less common in H chondrites, and absent in enstatite chondrites. We used x-ray mapping and traditional electron microprobe techniques to characterize bleached chondrules in a cross section of ordinary chondrites. We studied bleached chondrules from Semarkona by ion microprobe for trace elements and H isotopes, and by transmission electron microscopy. Chondrule bleaching was the result of low-temperature alteration by aqueous fluids flowing through fine-grained chondrite matrix prior to thermal metamorphism. During aqueous alteration, interstitial glass dissolved and was partially replaced by phyllosilicates, troilite was altered to pentlandite, but pyroxene was completely unaffected. Calcium-rich zones formed at the inner margins of the bleached zones, either as the result of the early stages of metamorphism or because of fluid-chondrule reaction. The mineralogy of bleached chondrules is extremely sensitive to thermal metamorphism in type 3 ordinary chondrites, and bleached zones provide a favorable location for the growth of metamorphic minerals in higher petrologic types. The ubiquitous presence of bleached chondrules in ordinary chondrites implies that they all experienced aqueous alteration early in their asteroidal histories, but there is no relationship between the degree of alteration and metamorphic grade. A correlation between the oxidation state of chondrite groups and their degree of aqueous alteration is consistent with the source of water being either accreted ices or water released during oxidation of organic matter. Ordinary chondrites were probably open systems after accretion, and aqueous fluids may have carried volatile elements with them during dehydration. Individual radial pyroxene and cryptocrystalline chondrules were certainly open systems in all chondrites that experienced aqueous alteration leading to bleaching.

Change in algal symbiont communities after bleaching, not prior heat exposure, increases heat tolerance of reef corals.

PubMed

Silverstein, Rachel N; Cunning, Ross; Baker, Andrew C

2015-01-01

Mutualistic organisms can be particularly susceptible to climate change stress, as their survivorship is often limited by the most vulnerable partner. However, symbiotic plasticity can also help organisms in changing environments by expanding their realized niche space. Coral-algal (Symbiodinium spp.) symbiosis exemplifies this dichotomy: the partnership is highly susceptible to 'bleaching' (stress-induced symbiosis breakdown), but stress-tolerant symbionts can also sometimes mitigate bleaching. Here, we investigate the role of diverse and mutable symbiotic partnerships in increasing corals' ability to thrive in high temperature conditions. We conducted repeat bleaching and recovery experiments on the coral Montastraea cavernosa, and used quantitative PCR and chlorophyll fluorometry to assess the structure and function of Symbiodinium communities within coral hosts. During an initial heat exposure (32 °C for 10 days), corals hosting only stress-sensitive symbionts (Symbiodinium C3) bleached, but recovered (at either 24 °C or 29 °C) with predominantly (>90%) stress-tolerant symbionts (Symbiodinium D1a), which were not detected before bleaching (either due to absence or extreme low abundance). When a second heat stress (also 32 °C for 10 days) was applied 3 months later, corals that previously bleached and were now dominated by D1a Symbiodinium experienced less photodamage and symbiont loss compared to control corals that had not been previously bleached, and were therefore still dominated by Symbiodinium C3. Additional corals that were initially bleached without heat by a herbicide (DCMU, at 24 °C) also recovered predominantly with D1a symbionts, and similarly lost fewer symbionts during subsequent thermal stress. Increased thermotolerance was also not observed in C3-dominated corals that were acclimated for 3 months to warmer temperatures (29 °C) before heat stress. These findings indicate that increased thermotolerance post-bleaching resulted from symbiont community composition changes, not prior heat exposure. Moreover, initially undetectable D1a symbionts became dominant only after bleaching, and were critical to corals' resilience after stress and resistance to future stress. © 2014 John Wiley & Sons Ltd.

Resilience and climate change: lessons from coral reefs and bleaching in the Western Indian Ocean

NASA Astrophysics Data System (ADS)

Obura, David O.

2005-05-01

The impact of climate change through thermal stress-related coral bleaching on coral reefs of the Western Indian Ocean has been well documented and is caused by rising sea water temperatures associated with background warming trends and extreme climate events. Recent studies have identified a number of factors that may reduce the impact of coral bleaching and mortality at a reef or sub-reef level. However, there is little scientific consensus as yet, and it is unclear how well current science supports the immediate needs of management responses to climate change. This paper provides evidence from the Western Indian Ocean in support of recent hypotheses on coral and reef vulnerability to thermal stress that have been loosely termed 'resistance and resilience to bleaching'. The paper argues for a more explicit definition of terms, and identifies three concepts affecting coral-zooxanthellae holobiont and reef vulnerability to thermal stress previously termed 'resistance to bleaching': 'thermal protection', where some reefs are protected from the thermal conditions that induce bleaching and/or where local physical conditions reduce bleaching and mortality levels; 'thermal resistance', where individual corals bleach to differing degrees to the same thermal stress; and 'thermal tolerance', where individual corals suffer differing levels of mortality when exposed to the same thermal stress. 'Resilience to bleaching' is a special case of ecological resilience, where recovery following large-scale bleaching mortality varies according to ecological and other processes. These concepts apply across multiple levels of biological organization and temporal and spatial scales. Thermal resistance and tolerance are genetic properties and may interact with environmental protection properties resulting in phenotypic variation in bleaching and mortality of corals. The presence or absence of human threats and varying levels of reef management may alter the influence of the above factors, particularly through their impacts on resilience, offering the opportunity for management interventions to mitigate the impacts of thermal stress and recovery on coral reefs. These concepts are compiled within an overarching framework of spatial resilience theory. This provides a framework for developing linked scientific and management questions relating to the larger scale impacts of climate change on coral reefs, their management needs and prospects for their future.

BioPCD - A Language for GUI Development Requiring a Minimal Skill Set

PubMed Central

Alvare, Graham GM; Roche-Lima, Abiel; Fristensky, Brian

2016-01-01

BioPCD is a new language whose purpose is to simplify the creation of Graphical User Interfaces (GUIs) by biologists with minimal programming skills. The first step in developing BioPCD was to create a minimal superset of the language referred to as PCD (Pythonesque Command Description). PCD defines the core of terminals and high-level nonterminals required to describe data of almost any type. BioPCD adds to PCD the constructs necessary to describe GUI components and the syntax for executing system commands. BioPCD is implemented using JavaCC to convert the grammar into code. BioPCD is designed to be terse and readable and simple enough to be learned by copying and modifying existing BioPCD files. We demonstrate that BioPCD can easily be used to generate GUIs for existing command line programs. Although BioPCD was designed to make it easier to run bioinformatics programs, it could be used in any domain in which many useful command line programs exist that do not have GUI interfaces. PMID:27818582

The Bleaching Syndrome: The Role of Educational Intervention

ERIC Educational Resources Information Center

Hall, Ronald E.

2016-01-01

Per the Bleaching Syndrome, people of color, including African, Asian, and Latino Americans, are both victims and perpetrators of color discrimination. The Bleaching Syndrome encompasses perceptual, psychological, and behavioral sectors that affect students' schooling experiences. Education professionals, including teachers, administrators, and…

Skeletal records of community-level bleaching in Porites corals from Palau

NASA Astrophysics Data System (ADS)

Barkley, Hannah C.; Cohen, Anne L.

2016-12-01

Tropical Pacific sea surface temperature is projected to rise an additional 2-3 °C by the end of this century, driving an increase in the frequency and intensity of coral bleaching. With significant global coral reef cover already lost due to bleaching-induced mortality, efforts are underway to identify thermally tolerant coral communities that might survive projected warming. Massive, long-lived corals accrete skeletal bands of anomalously high density in response to episodes of thermal stress. These "stress bands" are potentially valuable proxies for thermal tolerance, but to date their application to questions of community bleaching history has been limited. Ecological surveys recorded bleaching of coral communities across the Palau archipelago during the 1998 and 2010 warm events. Between 2011 and 2015, we extracted skeletal cores from living Porites colonies at 10 sites spanning barrier reef and lagoon environments and quantified the proportion of stress bands present in each population during bleaching years. Across Palau, the prevalence of stress bands tracked the severity of thermal stress, with more stress bands occurring in 1998 (degree heating weeks = 13.57 °C-week) than during the less severe 2010 event (degree heating weeks = 4.86 °C-week). Stress band prevalence also varied by reef type, as more corals on the exposed barrier reef formed stress bands than did corals from sheltered lagoon environments. Comparison of Porites stress band prevalence with bleaching survey data revealed a strong correlation between percent community bleaching and the proportion of colonies with stress bands in each year. Conversely, annual calcification rates did not decline consistently during bleaching years nor did annually resolved calcification histories always track interannual variability in temperature. Our data suggest that stress bands in massive corals contain valuable information about spatial and temporal trends in coral reef bleaching and can aid in conservation efforts to identify temperature-tolerant coral reef communities.

Unprecedented Mass Bleaching and Loss of Coral across 12° of Latitude in Western Australia in 2010–11

PubMed Central

Moore, James A. Y.; Bellchambers, Lynda M.; Depczynski, Martial R.; Evans, Richard D.; Evans, Scott N.; Field, Stuart N.; Friedman, Kim J.; Gilmour, James P.; Holmes, Thomas H.; Middlebrook, Rachael; Radford, Ben T.; Ridgway, Tyrone; Shedrawi, George; Taylor, Heather; Thomson, Damian P.; Wilson, Shaun K.

2012-01-01

Background Globally, coral bleaching has been responsible for a significant decline in both coral cover and diversity over the past two decades. During the summer of 2010–11, anomalous large-scale ocean warming induced unprecedented levels of coral bleaching accompanied by substantial storminess across more than 12° of latitude and 1200 kilometers of coastline in Western Australia (WA). Methodology/Principal Findings Extreme La-Niña conditions caused extensive warming of waters and drove considerable storminess and cyclonic activity across WA from October 2010 to May 2011. Satellite-derived sea surface temperature measurements recorded anomalies of up to 5°C above long-term averages. Benthic surveys quantified the extent of bleaching at 10 locations across four regions from tropical to temperate waters. Bleaching was recorded in all locations across regions and ranged between 17% (±5.5) in the temperate Perth region, to 95% (±3.5) in the Exmouth Gulf of the tropical Ningaloo region. Coincident with high levels of bleaching, three cyclones passed in close proximity to study locations around the time of peak temperatures. Follow-up surveys revealed spatial heterogeneity in coral cover change with four of ten locations recording significant loss of coral cover. Relative decreases ranged between 22%–83.9% of total coral cover, with the greatest losses in the Exmouth Gulf. Conclusions/Significance The anomalous thermal stress of 2010–11 induced mass bleaching of corals along central and southern WA coral reefs. Significant coral bleaching was observed at multiple locations across the tropical-temperate divide spanning more than 1200 km of coastline. Resultant spatially patchy loss of coral cover under widespread and high levels of bleaching and cyclonic activity, suggests a degree of resilience for WA coral communities. However, the spatial extent of bleaching casts some doubt over hypotheses suggesting that future impacts to coral reefs under forecast warming regimes may in part be mitigated by southern thermal refugia. PMID:23284773

Unprecedented mass bleaching and loss of coral across 12° of latitude in Western Australia in 2010-11.

PubMed

Moore, James A Y; Bellchambers, Lynda M; Depczynski, Martial R; Evans, Richard D; Evans, Scott N; Field, Stuart N; Friedman, Kim J; Gilmour, James P; Holmes, Thomas H; Middlebrook, Rachael; Radford, Ben T; Ridgway, Tyrone; Shedrawi, George; Taylor, Heather; Thomson, Damian P; Wilson, Shaun K

2012-01-01

Globally, coral bleaching has been responsible for a significant decline in both coral cover and diversity over the past two decades. During the summer of 2010-11, anomalous large-scale ocean warming induced unprecedented levels of coral bleaching accompanied by substantial storminess across more than 12° of latitude and 1200 kilometers of coastline in Western Australia (WA). Extreme La-Niña conditions caused extensive warming of waters and drove considerable storminess and cyclonic activity across WA from October 2010 to May 2011. Satellite-derived sea surface temperature measurements recorded anomalies of up to 5°C above long-term averages. Benthic surveys quantified the extent of bleaching at 10 locations across four regions from tropical to temperate waters. Bleaching was recorded in all locations across regions and ranged between 17% (±5.5) in the temperate Perth region, to 95% (±3.5) in the Exmouth Gulf of the tropical Ningaloo region. Coincident with high levels of bleaching, three cyclones passed in close proximity to study locations around the time of peak temperatures. Follow-up surveys revealed spatial heterogeneity in coral cover change with four of ten locations recording significant loss of coral cover. Relative decreases ranged between 22%-83.9% of total coral cover, with the greatest losses in the Exmouth Gulf. The anomalous thermal stress of 2010-11 induced mass bleaching of corals along central and southern WA coral reefs. Significant coral bleaching was observed at multiple locations across the tropical-temperate divide spanning more than 1200 km of coastline. Resultant spatially patchy loss of coral cover under widespread and high levels of bleaching and cyclonic activity, suggests a degree of resilience for WA coral communities. However, the spatial extent of bleaching casts some doubt over hypotheses suggesting that future impacts to coral reefs under forecast warming regimes may in part be mitigated by southern thermal refugia.

Mass coral bleaching due to unprecedented marine heatwave in Papahānaumokuākea Marine National Monument (Northwestern Hawaiian Islands).

PubMed

Couch, Courtney S; Burns, John H R; Liu, Gang; Steward, Kanoelani; Gutlay, Tiffany Nicole; Kenyon, Jean; Eakin, C Mark; Kosaki, Randall K

2017-01-01

2014 marked the sixth and most widespread mass bleaching event reported in the Northwestern Hawaiian Islands, home to the Papahānaumokuākea Marine National Monument (PMNM), the world's second largest marine reserve. This event was associated with an unusual basin-scale warming in the North Pacific Ocean, with an unprecedented peak intensity of around 20°C-weeks of cumulative heat stress at Lisianksi Island. In situ bleaching surveys and satellite data were used to evaluate the relative importance of potential drivers of bleaching patterns in 2014, assess the subsequent morality and its effects on coral communities and 3D complexity, test for signs of regional acclimation, and investigate long-term change in heat stress in PMNM. Surveys conducted at four island/atoll (French Frigate Shoals, Lisianski Island, Pearl and Hermes Atoll, and Midway Atoll) showed that in 2014, percent bleaching varied considerably between islands/atolls and habitats (back reef/fore reef and depth), and was up to 91% in shallow habitats at Lisianski. The percent bleaching during the 2014 event was best explained by a combination of duration of heat stress measured by Coral Reef Watch's satellite Degree Heating Week, relative community susceptibility (bleaching susceptibility score of each taxon * the taxon's abundance relative to the total number of colonies), depth and region. Mean coral cover at permanent Lisianski monitoring sites decreased by 68% due to severe losses of Montipora dilatata complex, resulting in rapid reductions in habitat complexity. Spatial distribution of the 2014 bleaching was significantly different from the 2002 and 2004 bleaching events likely due to a combination of differences in heat stress and local acclimatization. Historical satellite data demonstrated heat stress in 2014 was unlike any previous event and that the exposure of corals to the bleaching-level heat stress has increased significantly in the northern PMNM since 1982, highlighting the increasing threat of climate change to reefs.

The Delineation of Coral Bleaching Thresholds and Future Reef Health, Little Cayman Cayman Islands

NASA Astrophysics Data System (ADS)

Manfrino, C.; Van Hooidonk, R. J.; Manzello, D.; Hendee, J.

2011-12-01

The global rise in sea temperature through anthropogenic climate change is affecting coral reef ecosystems through a phenomenon known as coral bleaching; a common reaction to thermally induced physiological stress in reef-building corals that often leads to coral mortality. We describe aspects of the most prevalent episode of coral bleaching ever recorded at Little Cayman, Cayman Islands, during the fall of 2009. Scleractinian coral species exhibiting susceptibility to thermal stress and bleaching in Little Cayman were, in order, Siderastrea siderea, Montastraea annularis, and Montastraea faveolata, while Diplora strigosa and Agaricia spp. were less so, yet still showed considerable bleaching prevalence and severity. In contrast, the least susceptible were Porites porites, Porites astreoides, and Montastraea cavernosa. These observations and other reported observations of coral bleaching, together with 29 years (1982 - 2010) of satellite-derived sea surface temperatures, were used in a Degree Heating Weeks (DHW) and Peirce Skill Score (PSS) analysis to calculate a bleaching threshold above which bleaching was expected to occur. A threshold of 4.2 DHW had the highest skill, with a PSS of 0.70. This threshold and susceptibility ranking are used in combination with SST data from global, coupled ocean-atmosphere general circulation models (GCM) from the fourth IPCC assessment to forecast future reef health on Little Cayman. While these GCMs possess skill in reproducing many aspects of climate, they vary in their ability to correctly capture such parameters as the tropical ocean seasonal cycle and El Niño Southern Oscillation (ENSO) variability. These model weaknesses likely reduce the skill of coral bleaching predictions. To overcome this, a multi-model ensemble of GCMs are corrected for their mean, annual cycle and ENSO variability prior to calculating future thermal stress. Preliminary results show that from 2045 on Little Cayman is likely to see more than two massive bleaching episodes per decade.

Childhood Physical and Sexual Abuse in Caribbean Young Adults and Its Association with Depression, Post-Traumatic Stress, and Skin Bleaching

PubMed Central

James, Caryl; Seixas, Azizi A; Harrison, Abigail; Jean-Louis, Girardin; Butler, Mark; Zizi, Ferdinand; Samuels, Alafia

2016-01-01

Background The global prevalence of skin depigmentation/skin bleaching among blacks, estimated at 35%, is on the rise and is associated with a host of negative health and medical consequences. Current etiological approaches do not fully capture the emotional and psychological underpinnings of skin bleaching. The current study investigated the potential mediating role of depression, or post-traumatic stress symptoms (avoidance and hyperarousal) on the relationship between childhood physical and sexual abuse (CPSA) and skin bleaching. Methods A total of 1226 university participants (ages 18–30 years and 63.4% female) from three Caribbean countries (Jamaica, Barbados, and Grenada) provided data for the current analysis. They all completed self-reported measures of general demographic information along with the short screening scale for posttraumatic stress disorder (DSM-IV), childhood trauma, and skin bleaching questions. Results The prevalence of skin bleaching in our study was 25.4%. Our findings showed that individuals who bleached their skin were more likely to have been abused as children (21.6% versus 13.5%, p<0.001), were more likely to have significant symptoms of trauma (34.1% versus 24.0%, p=0.005), and were more likely to have significant depression (43.7% versus 35.1%, p=0.032). We found that trauma-related hyperarousal symptoms positively mediated the relationship between childhood physical and sexual abuse and skin bleaching (Indirect Effect=0.03, p<0.05), while avoidance (Indirect Effect=0.000, p>0.05) and depressive (Indirect Effect=0.005, p>0.05) symptoms did not. Conclusion The presence of trauma symptoms and childhood physical and sexual abuse (CPSA) may increase the likelihood of skin bleaching. Findings suggest that further exploration is needed to ascertain if the presence of skin bleaching warrants being also screened for trauma. PMID:27019771

Mass coral bleaching due to unprecedented marine heatwave in Papahānaumokuākea Marine National Monument (Northwestern Hawaiian Islands)

PubMed Central

Couch, Courtney S.; Burns, John H. R.; Liu, Gang; Steward, Kanoelani; Gutlay, Tiffany Nicole; Kenyon, Jean; Eakin, C. Mark; Kosaki, Randall K.

2017-01-01

2014 marked the sixth and most widespread mass bleaching event reported in the Northwestern Hawaiian Islands, home to the Papahānaumokuākea Marine National Monument (PMNM), the world’s second largest marine reserve. This event was associated with an unusual basin-scale warming in the North Pacific Ocean, with an unprecedented peak intensity of around 20°C-weeks of cumulative heat stress at Lisianksi Island. In situ bleaching surveys and satellite data were used to evaluate the relative importance of potential drivers of bleaching patterns in 2014, assess the subsequent morality and its effects on coral communities and 3D complexity, test for signs of regional acclimation, and investigate long-term change in heat stress in PMNM. Surveys conducted at four island/atoll (French Frigate Shoals, Lisianski Island, Pearl and Hermes Atoll, and Midway Atoll) showed that in 2014, percent bleaching varied considerably between islands/atolls and habitats (back reef/fore reef and depth), and was up to 91% in shallow habitats at Lisianski. The percent bleaching during the 2014 event was best explained by a combination of duration of heat stress measured by Coral Reef Watch’s satellite Degree Heating Week, relative community susceptibility (bleaching susceptibility score of each taxon * the taxon’s abundance relative to the total number of colonies), depth and region. Mean coral cover at permanent Lisianski monitoring sites decreased by 68% due to severe losses of Montipora dilatata complex, resulting in rapid reductions in habitat complexity. Spatial distribution of the 2014 bleaching was significantly different from the 2002 and 2004 bleaching events likely due to a combination of differences in heat stress and local acclimatization. Historical satellite data demonstrated heat stress in 2014 was unlike any previous event and that the exposure of corals to the bleaching-level heat stress has increased significantly in the northern PMNM since 1982, highlighting the increasing threat of climate change to reefs. PMID:28953909

The effectiveness of low-intensity red laser for activating a bleaching gel and its effect in temperature of the bleaching gel and the dental pulp.

PubMed

Pleffken, Patrícia Rondon; Borges, Alessandra Bühler; Gonçalves, Sérgio Eduardo D E Paiva; Rocha Gomes Torres, Carlos

2012-04-01

The effectiveness of low-intensity red laser for activating a bleaching gel and its effect in pulp temperature was not investigated in dental literature. The objective of this study was to assess the effectiveness of low-intensity red laser for activating a bleaching gel, as well as its effect in temperature of the bleaching gel and the dental pulp. Forty extracted bovine teeth were immersed in a solution of coffee 14 days for darkening. The initial colors were recorded by spectrophotometric analysis. The specimens were randomly distributed into two groups (N = 20): the control, which did not receive light and the experimental group that received light from an appliance fitted with three red light-emitting laser diodes (λ = 660 nm). A green-colored, 35% H(2) O(2) -based bleaching gel was applied for 30 minutes, and changed three times. After bleaching, the colors were again measured to obtain the L*a*b* values. Color variation was calculated (ΔE) and the data submitted to the non-paired t-test (5%). To assess temperature, 10 human incisors were prepared, in which one thermocouple was placed on the bleaching gel applied on the surface of the teeth and another inside the pulp chamber. There was a significant difference between the groups (p = 0.016), and the experimental group presented a significantly higher mean variation (7.21 ± 2.76) in comparison with the control group (5.37 ± 1.76). There was an increase in pulp temperature, but it was not sufficient to cause damage to the pulp. Bleaching gel activation with low-intensity red laser was capable of increasing the effectiveness of bleaching treatment and did not increase pulp temperature to levels deleterious to the pulp. © 2011 Wiley Periodicals, Inc.

Physiological and biogeochemical traits of bleaching and recovery in the mounding species of coral Porites lobata: implications for resilience in mounding corals.

PubMed

Levas, Stephen J; Grottoli, Andréa G; Hughes, Adam; Osburn, Christopher L; Matsui, Yohei

2013-01-01

Mounding corals survive bleaching events in greater numbers than branching corals. However, no study to date has determined the underlying physiological and biogeochemical trait(s) that are responsible for mounding coral holobiont resilience to bleaching. Furthermore, the potential of dissolved organic carbon (DOC) as a source of fixed carbon to bleached corals has never been determined. Here, Porites lobata corals were experimentally bleached for 23 days and then allowed to recover for 0, 1, 5, and 11 months. At each recovery interval a suite of analyses were performed to assess their recovery (photosynthesis, respiration, chlorophyll a, energy reserves, tissue biomass, calcification, δ(13)C of the skeletal, δ(13)C, and δ(15)N of the animal host and endosymbiont fractions). Furthermore, at 0 months of recovery, the assimilation of photosynthetically acquired and zooplankton-feeding acquired carbon into the animal host, endosymbiont, skeleton, and coral-mediated DOC were measured via (13)C-pulse-chase labeling. During the first month of recovery, energy reserves and tissue biomass in bleached corals were maintained despite reductions in chlorophyll a, photosynthesis, and the assimilation of photosynthetically fixed carbon. At the same time, P. lobata corals catabolized carbon acquired from zooplankton and seemed to take up DOC as a source of fixed carbon. All variables that were negatively affected by bleaching recovered within 5 to 11 months. Thus, bleaching resilience in the mounding coral P. lobata is driven by its ability to actively catabolize zooplankton-acquired carbon and seemingly utilize DOC as a significant fixed carbon source, facilitating the maintenance of energy reserves and tissue biomass. With the frequency and intensity of bleaching events expected to increase over the next century, coral diversity on future reefs may favor not only mounding morphologies but species like P. lobata, which have the ability to utilize heterotrophic sources of fixed carbon that minimize the impact of bleaching and promote fast recovery.

Physiological and Biogeochemical Traits of Bleaching and Recovery in the Mounding Species of Coral Porites lobata: Implications for Resilience in Mounding Corals

PubMed Central

Levas, Stephen J.; Grottoli, Andréa G.; Hughes, Adam; Osburn, Christopher L.; Matsui, Yohei

2013-01-01

Mounding corals survive bleaching events in greater numbers than branching corals. However, no study to date has determined the underlying physiological and biogeochemical trait(s) that are responsible for mounding coral holobiont resilience to bleaching. Furthermore, the potential of dissolved organic carbon (DOC) as a source of fixed carbon to bleached corals has never been determined. Here, Porites lobata corals were experimentally bleached for 23 days and then allowed to recover for 0, 1, 5, and 11 months. At each recovery interval a suite of analyses were performed to assess their recovery (photosynthesis, respiration, chlorophyll a, energy reserves, tissue biomass, calcification, δ13C of the skeletal, δ13C, and δ15N of the animal host and endosymbiont fractions). Furthermore, at 0 months of recovery, the assimilation of photosynthetically acquired and zooplankton-feeding acquired carbon into the animal host, endosymbiont, skeleton, and coral-mediated DOC were measured via 13C-pulse-chase labeling. During the first month of recovery, energy reserves and tissue biomass in bleached corals were maintained despite reductions in chlorophyll a, photosynthesis, and the assimilation of photosynthetically fixed carbon. At the same time, P. lobata corals catabolized carbon acquired from zooplankton and seemed to take up DOC as a source of fixed carbon. All variables that were negatively affected by bleaching recovered within 5 to 11 months. Thus, bleaching resilience in the mounding coral P. lobata is driven by its ability to actively catabolize zooplankton-acquired carbon and seemingly utilize DOC as a significant fixed carbon source, facilitating the maintenance of energy reserves and tissue biomass. With the frequency and intensity of bleaching events expected to increase over the next century, coral diversity on future reefs may favor not only mounding morphologies but species like P. lobata, which have the ability to utilize heterotrophic sources of fixed carbon that minimize the impact of bleaching and promote fast recovery. PMID:23658817

Effect of three nanobiomaterials on microhardness of bleached enamel

PubMed Central

Kaveh, Sara

2016-01-01

Objectives The aim of this in vitro study was to evaluate the effect of incorporating three different nanobiomaterials into bleaching material on microhardness of bleached enamel. Materials and Methods The crowns of 24 extracted sound human molars were sectioned. Sixty enamel specimens (2 × 3 × 4 mm) were selected and divided into five groups (n = 12): Group 1 received no bleaching procedure (control); Group 2 underwent bleaching with a 40% hydrogen peroxide (HP) gel; Groups 3, 4, and 5 were bleached with a 40% HP gel modified by incorporation of bioactive glass (BAG), amorphous calcium phosphate (ACP) and hydroxyapatite (HA), respectively. The enamel microhardness was evaluated. The differences in Knoop microhardness data of each group were analyzed by one-way ANOVA, followed by post hoc Tukey tests. Results Significant differences were observed between the study groups. The enamel microhardness changes in Groups 1, 3, 4, and 5 were significantly lower than that of Group 2 (p < 0.001). Conclusions Within the limitations of this study, it can be concluded that incorporation of each one of the three tested biomaterials as remineralizing agents might be effective in decreasing enamel microhardness changes subsequent to in-office bleaching. PMID:27508161

Reef fishes can recognize bleached habitat during settlement: sea anemone bleaching alters anemonefish host selection

PubMed Central

Scott, Anna; Dixson, Danielle L.

2016-01-01

Understanding how bleaching impacts the settlement of symbiotic habitat specialists and whether there is flexibility in settlement choices with regard to habitat quality is essential given our changing climate. We used five anemonefishes (Amphiprion clarkii, Amphiprion latezonatus, Amphiprion ocellaris, Amphiprion percula and Premnas biaculeatus) and three host sea anemones (Entacmaea quadricolor, Heteractis crispa and Heteractis magnifica) in paired-choice flume experiments to determine whether habitat naive juveniles have the olfactory capabilities to distinguish between unbleached and bleached hosts, and how this may affect settlement decisions. All anemonefishes were able to distinguish between bleached and unbleached hosts, and responded only to chemical cues from species-specific host anemones irrespective of health status, indicating a lack of flexibility in host use. While bleached hosts were selected as habitat, this occurred only when unbleached options were unavailable, with the exception of A. latezonatus, which showed strong preferences for H. crispa regardless of health. This study highlights the potential deleterious indirect impacts of declining habitat quality during larval settlement in habitat specialists, which could be important in the field, given that bleaching events are becoming increasingly common. PMID:27226472

Tenacious D: Symbiodinium in clade D remain in reef corals at both high and low temperature extremes despite impairment.

PubMed

Silverstein, Rachel N; Cunning, Ross; Baker, Andrew C

2017-04-01

Reef corals are sensitive to thermal stress, which induces coral bleaching (the loss of algal symbionts), often leading to coral mortality. However, corals hosting certain symbionts (notably some members of Symbiodinium clade D) resist bleaching when exposed to high temperatures. To determine whether these symbionts are also cold tolerant, we exposed corals hosting either Symbiodinium C3 or D1a to incremental warming (+1°C week -1 to 35°C) and cooling (-1°C week -1 to 15°C), and measured photodamage and symbiont loss. During warming to 33°C, C3 corals were photodamaged and lost >99% of symbionts, while D1a corals experienced photodamage but did not bleach. During cooling, D1a corals suffered more photodamage than C3 corals but still did not bleach, while C3 corals lost 94% of symbionts. These results indicate that photodamage does not always lead to bleaching, suggesting alternate mechanisms exist by which symbionts resist bleaching, and helping explain the persistence of D1a symbionts on recently bleached reefs, with implications for the future of these ecosystems. © 2017. Published by The Company of Biologists Ltd.

Reef fishes can recognize bleached habitat during settlement: sea anemone bleaching alters anemonefish host selection.

PubMed

Scott, Anna; Dixson, Danielle L

2016-05-25

Understanding how bleaching impacts the settlement of symbiotic habitat specialists and whether there is flexibility in settlement choices with regard to habitat quality is essential given our changing climate. We used five anemonefishes (Amphiprion clarkii, Amphiprion latezonatus, Amphiprion ocellaris, Amphiprion percula and Premnas biaculeatus) and three host sea anemones (Entacmaea quadricolor, Heteractis crispa and Heteractis magnifica) in paired-choice flume experiments to determine whether habitat naive juveniles have the olfactory capabilities to distinguish between unbleached and bleached hosts, and how this may affect settlement decisions. All anemonefishes were able to distinguish between bleached and unbleached hosts, and responded only to chemical cues from species-specific host anemones irrespective of health status, indicating a lack of flexibility in host use. While bleached hosts were selected as habitat, this occurred only when unbleached options were unavailable, with the exception of A. latezonatus, which showed strong preferences for H. crispa regardless of health. This study highlights the potential deleterious indirect impacts of declining habitat quality during larval settlement in habitat specialists, which could be important in the field, given that bleaching events are becoming increasingly common. © 2016 The Author(s).

The effect of bleaching on the terpene chemistry of Plexaurella fusifera: evidence that zooxanthellae are not responsible for sesquiterpene production.

PubMed

Frenz-Ross, Jamie L; Enticknap, Julie J; Kerr, Russell G

2008-01-01

The close association between marine invertebrates, zooxanthellae, and numerous bacteria gives rise to the question of the identity of the actual producer of secondary metabolites. In fall of 2005, a widespread bleaching event occurred throughout the Caribbean Sea in which some colonies of the gorgonian coral Plexaurella fusifera bleached. This study investigated whether zooxanthellae play a key role in the biosynthesis of secondary metabolite terpenes from P. fusifera. The extent of bleaching was examined by chlorophyll A analysis and also by zooxanthellae isolation and cell counting. The bleached and unbleached colonies were found to contain similar concentrations of eremophilene as the major terpene, and both exhibited similar biosynthetic capability as evaluated by the transformation of [C(1)-(3)H]-farnesyl diphosphate to the sesquiterpenes. Differences in bacterial communities between the bleached and unbleached colonies were analyzed using molecular techniques, and preliminary indications are that unbleached and bleached corals are dominated by low G + C firmicutes and gammaproteobacteria, respectively. It therefore appears that terpene biosynthesis can proceed independently of the zooxanthellae in P. fusifera, suggesting that the coral or a bacterium is the biosynthetic source.

An innovative chairside bleaching protocol for treating stained dentition: initial results.

PubMed

Miara, P

2000-09-01

For years, investigators have attempted to develop a predictable means of bleaching pathologically and nonpathologically stained dentition. While previous efforts have modified the concentration of the bleaching material, the duration of the procedure, and the manner by which the bleaching agent is activated, the ability to affect a significant shade improvement remains an elusive objective. This article demonstrates an innovative technique used to influence the penetration of oxygen ions into the tooth enamel, which may resolve this clinical dilemma.

Viability of Commercially Available Bleach for Water Treatment in Developing Countries

PubMed Central

2009-01-01

Treating household water with low-cost, widely available commercial bleach is recommended by some organizations to improve water quality and reduce disease in developing countries. I analyzed the chlorine concentration of 32 bleaches from 12 developing countries; the average error between advertised and measured concentration was 35% (range = –45%–100%; standard deviation = 40%). Because of disparities between advertised and actual concentration, the use of commercial bleach for water treatment in developing countries is not recommended without ongoing quality control testing. PMID:19762657

Viability of commercially available bleach for water treatment in developing countries.

PubMed

Lantagne, Daniele S

2009-11-01

Treating household water with low-cost, widely available commercial bleach is recommended by some organizations to improve water quality and reduce disease in developing countries. I analyzed the chlorine concentration of 32 bleaches from 12 developing countries; the average error between advertised and measured concentration was 35% (range = -45%-100%; standard deviation = 40%). Because of disparities between advertised and actual concentration, the use of commercial bleach for water treatment in developing countries is not recommended without ongoing quality control testing.

Direct Bio-printing with Heterogeneous Topology Design.

PubMed

Ahsan, Amm Nazmul; Xie, Ruinan; Khoda, Bashir

2017-01-01

Bio-additive manufacturing is a promising tool to fabricate porous scaffold structures for expediting the tissue regeneration processes. Unlike the most traditional bulk material objects, the microstructures of tissue and organs are mostly highly anisotropic, heterogeneous, and porous in nature. However, modelling the internal heterogeneity of tissues/organs structures in the traditional CAD environment is difficult and oftentimes inaccurate. Besides, the de facto STL conversion of bio-models introduces loss of information and piles up more errors in each subsequent step (build orientation, slicing, tool-path planning) of the bio-printing process plan. We are proposing a topology based scaffold design methodology to accurately represent the heterogeneous internal architecture of tissues/organs. An image analysis technique is used that digitizes the topology information contained in medical images of tissues/organs. A weighted topology reconstruction algorithm is implemented to represent the heterogeneity with parametric functions. The parametric functions are then used to map the spatial material distribution. The generated information is directly transferred to the 3D bio-printer and heterogeneous porous tissue scaffold structure is manufactured without STL file. The proposed methodology is implemented to verify the effectiveness of the approach and the designed example structure is bio-fabricated with a deposition based bio-additive manufacturing system.

Cascade use indicators for selected biopolymers: Are we aiming for the right solutions in the design for recycling of bio-based polymers?

PubMed

Hildebrandt, Jakob; Bezama, Alberto; Thrän, Daniela

2017-04-01

When surveying the trends and criteria for the design for recycling (DfR) of bio-based polymers, priorities appear to lie in energy recovery at the end of the product life of durable products, such as bio-based thermosets. Non-durable products made of thermoplastic polymers exhibit good properties for material recycling. The latter commonly enjoy growing material recycling quotas in countries that enforce a landfill ban. Quantitative and qualitative indicators are needed for characterizing progress in the development towards more recycling friendly bio-based polymers. This would enable the deficits in recycling bio-based plastics to be tracked and improved. The aim of this paper is to analyse the trends in the DfR of bio-based polymers and the constraints posed by the recycling infrastructure on plastic polymers from a systems perspective. This analysis produces recommendations on how life cycle assessment indicators can be introduced into the dialogue between designers and recyclers in order to promote DfR principles to enhance the cascading use of bio-based polymers within the bioeconomy, and to meet circular economy goals.

Cascade use indicators for selected biopolymers: Are we aiming for the right solutions in the design for recycling of bio-based polymers?

PubMed Central

Hildebrandt, Jakob; Bezama, Alberto; Thrän, Daniela

2017-01-01

When surveying the trends and criteria for the design for recycling (DfR) of bio-based polymers, priorities appear to lie in energy recovery at the end of the product life of durable products, such as bio-based thermosets. Non-durable products made of thermoplastic polymers exhibit good properties for material recycling. The latter commonly enjoy growing material recycling quotas in countries that enforce a landfill ban. Quantitative and qualitative indicators are needed for characterizing progress in the development towards more recycling friendly bio-based polymers. This would enable the deficits in recycling bio-based plastics to be tracked and improved. The aim of this paper is to analyse the trends in the DfR of bio-based polymers and the constraints posed by the recycling infrastructure on plastic polymers from a systems perspective. This analysis produces recommendations on how life cycle assessment indicators can be introduced into the dialogue between designers and recyclers in order to promote DfR principles to enhance the cascading use of bio-based polymers within the bioeconomy, and to meet circular economy goals. PMID:28097922

Engineering Strategies to Decode and Enhance the Genomes of Coral Symbionts.

PubMed

Levin, Rachel A; Voolstra, Christian R; Agrawal, Shobhit; Steinberg, Peter D; Suggett, David J; van Oppen, Madeleine J H

2017-01-01

Elevated sea surface temperatures from a severe and prolonged El Niño event (2014-2016) fueled by climate change have resulted in mass coral bleaching (loss of dinoflagellate photosymbionts, Symbiodinium spp., from coral tissues) and subsequent coral mortality, devastating reefs worldwide. Genetic variation within and between Symbiodinium species strongly influences the bleaching tolerance of corals, thus recent papers have called for genetic engineering of Symbiodinium to elucidate the genetic basis of bleaching-relevant Symbiodinium traits. However, while Symbiodinium has been intensively studied for over 50 years, genetic transformation of Symbiodinium has seen little success likely due to the large evolutionary divergence between Symbiodinium and other model eukaryotes rendering standard transformation systems incompatible. Here, we integrate the growing wealth of Symbiodinium next-generation sequencing data to design tailored genetic engineering strategies. Specifically, we develop a testable expression construct model that incorporates endogenous Symbiodinium promoters, terminators, and genes of interest, as well as an internal ribosomal entry site from a Symbiodinium virus. Furthermore, we assess the potential for CRISPR/Cas9 genome editing through new analyses of the three currently available Symbiodinium genomes. Finally, we discuss how genetic engineering could be applied to enhance the stress tolerance of Symbiodinium , and in turn, coral reefs.

Evaluation of the efficacy of bleach routinely used in health facilities against Mycobacterium tuberculosis isolates in Ethiopia

PubMed Central

Mekonnen, Daniel; Admassu, Aschalew; Wassie, Belaynew; Biadglegne, Fantahun

2015-01-01

Introduction In Ethiopia, the most widely used disinfectant is 5% Hypochlorites. However, Ethiopian national health safety and infection prevention guideline recommendation on the use of bleach is not consistent and varying from 0.1%-4%. The purpose of this study was therefore to assess the effective time-concentration relationship of sodium hypochlorite against Mycobacterium tuberculosis complex isolates in the absence of any organic load. Methods This experimental study was conducted in Bahir Dar Regional laboratory from February-June 2013. Test suspensions of 1.5 X 108 CFU/ml prepared using normal saline containing 0.5% tween 80. From 5% stock, 0.1%, 0.5%, 1% and 2% bleach was prepared. A 1ml of test strain suspension and 1ml of bleach mixed and allowed to stand until the specified time achieved, neutralized by 48 ml phosphate buffer. 100µl from the diluted sediment were spread on two L-J mediums and incubated at 37°C for 8 weeks. Results When 0. 1% bleach was used for 10 min, majority 11/20 of isolates showed 3 x 103 CFU/ml growth (ME = 4.4) which was inefficient. However, when the time increased, the log10 reduction was acceptable, ME >5 and it was effective. The bleach solution containing 0.5% and above was effective in all respective times. In this study, there is no difference observed in the tuberculocidal activity of bleach against resistant and sensitive strains. Conclusion Our study showed that in the absence of any organic load, 0.1% bleaches over 15 min and 0.5% bleaches over 10 min was found to be tuberculocidal. PMID:26668688

Evaluation of the effect of a home bleaching agent on surface characteristics of indirect esthetic restorative materials--part II microhardness.

PubMed

Torabi, Kianoosh; Rasaeipour, Sasan; Ghodsi, Safoura; Khaledi, Amir Ali Reza; Vojdani, Mahroo

2014-07-01

The exponential usage of esthetic restorative materials is beholden to society needs and desires. Interaction between the bleaching agents and the esthetic restorative materials is of critical importance. This in vitro study has been conducted to evaluate the effect of a home bleaching agent, carbamide peroxide (CP) 38%, on the microhardness of the fiber reinforced composite (FRC), overglazed, autoglazed, or polished porcelain specimens. For overglazed, autoglazed, polished ceramics and also FRC cylindrical specimens (n = 20 per group) were prepared. The specimens were stored in distilled water at 37°C for 48 hours prior to testing. Six samples from each group were selected randomly as negative controls which were stored in distilled water at 37°C that was changed daily. CP 38% was applied on the test specimens for 15 minutes, twice a day for 14 days. By using Knoop-microhardness tester microhardness testing for baseline, control and test specimens was conducted. Data were statistically analyzed using paired t-test, Mann-Whitney test, and Kruskal-Wallis test. Home bleaching significantly decreased the surface microhardness of all the test samples (p < 0.05), whereas the control groups did not show statistically significant changes after 2 weeks. The polished porcelain and polished composite specimens showed the most significant change in microhard-ness after bleaching process (p < 0.05). Although the type of surface preparation affects the susceptibility of the porcelain surface to the bleaching agent, no special preparation can preclude such adverse effects. The contact of home bleaching agents with esthetic restorative materials is unavoidable. Therefore protecting these restorations from bleaching agents and reglazing or at least polishing the restorations after bleaching is recommended.

Randomized controlled clinical trial on bleaching sensitivity and whitening efficacy of hydrogen peroxide versus combinations of hydrogen peroxide and ozone.

PubMed

Al-Omiri, Mahmoud K; Al Nazeh, Abdullah A; Kielbassa, Andrej M; Lynch, Edward

2018-02-05

The clinical efficacy regarding bleaching sensitivity and tooth shade lightening using a standard hydrogen peroxide (H 2 O 2 ) bleaching gel was compared with the additional use of ozone either before or after application of H 2 O 2 . Using computer-generated tables, 45 participants were randomly allocated into three groups (n = 15 each) in this investigator-driven, single-centre trial. In Group 1, upper anterior teeth were bleached using ozone (produced via a healOzone X4 device) for 60 seconds, then 38% H 2 O 2 for 20 minutes; in Group 2, 38% H 2 O 2 application (20 min) was followed by ozone (60 s); air produced by the healOzone machine (60 s) followed by 38% H 2 O 2 (20 min) was used in Group 3 (control). Bleaching sensitivity was evaluated via visual analogue scales, and a treatment-blinded reader objectively recorded tooth shades using a colorimeter before and 24 hours after bleaching (at α = 0.05). The H 2 O 2 /ozone combination did not result in pain sensations, while both ozone/H 2 O 2 and H 2 O 2 alone increased bleaching sensitivity (p < 0.001). Teeth achieved lighter shades (higher L*/lower b* values) after bleaching in all groups (p < 0.001), while Ozone boosted lighter tooth shades, irrespective of its use before or after H 2 O 2 (p < 0.05). Due to the complimentary effects, applying ozone after H 2 O 2 seems preferable for bleaching.

Influence of pH, bleaching agents, and acid etching on surface wear of bovine enamel

PubMed Central

Soares, Ana Flávia; Bombonatti, Juliana Fraga Soares; Alencar, Marina Studart; Consolmagno, Elaine Cristina; Honório, Heitor Marques; Mondelli, Rafael Francisco Lia

2016-01-01

ABSTRACT Development of new materials for tooth bleaching justifies the need for studies to evaluate the changes in the enamel surface caused by different bleaching protocols. Objective The aim of this study was to evaluate the bovine dental enamel wear in function of different bleaching gel protocols, acid etching and pH variation. Material and Methods Sixty fragments of bovine teeth were cut, obtaining a control and test areas. In the test area, one half received etching followed by a bleaching gel application, and the other half, only the bleaching gel. The fragments were randomly divided into six groups (n=10), each one received one bleaching session with five hydrogen peroxide gel applications of 8 min, activated with hybrid light, diode laser/blue LED (HL) or diode laser/violet LED (VHL) (experimental): Control (C); 35% Total Blanc Office (TBO35HL); 35% Lase Peroxide Sensy (LPS35HL); 25% Lase Peroxide Sensy II (LPS25HL); 15% Lase Peroxide Lite (LPL15HL); and 10% hydrogen peroxide (experimental) (EXP10VHL). pH values were determined by a pHmeter at the initial and final time periods. Specimens were stored, subjected to simulated brushing cycles, and the superficial wear was determined (μm). ANOVA and Tukey´s tests were applied (α=0.05). Results The pH showed a slight decrease, except for Group LPL15HL. Group LPS25HL showed the highest degree of wear, with and without etching. Conclusion There was a decrease from the initial to the final pH. Different bleaching gels were able to increase the surface wear values after simulated brushing. Acid etching before bleaching increased surface wear values in all groups. PMID:27008254

Evaluation of an experimental rat model for comparative studies of bleaching agents.

PubMed

Cintra, Luciano Tavares Angelo; Benetti, Francine; Ferreira, Luciana Louzada; Rahal, Vanessa; Ervolino, Edilson; Jacinto, Rogério de Castilho; Gomes Filho, João Eduardo; Briso, André Luiz Fraga

2016-04-01

Dental materials in general are tested in different animal models prior to the clinical use in humans, except for bleaching agents. Objectives To evaluate an experimental rat model for comparative studies of bleaching agents, by investigating the influence of different concentrations and application times of H2O2 gel in the pulp tissue during in-office bleaching of rats' vital teeth. Material and Methods The right and left maxillary molars of 50 Wistar rats were bleached with 20% and 35% H2O2 gels, respectively, for 5, 10, 15, 30, or 45 min (n=10 rats/group). Ten animals were untreated (control). The rats were killed after 2 or 30 days, and the maxillae were examined by light microscopy. Inflammation was evaluated through histomorphometric analysis with inflammatory cell count in the coronal and radicular thirds of the pulp. Fibroblasts were also counted. Scores were attributed to odontoblastic layer and vascular changes. Tertiary dentin area and pulp chamber central area were measured histomorphometrically. Data were compared by analysis of variance and Kruskal-Wallis test (p<0.05). Results After 2 days, the amount of inflammatory cells increased in the coronal pulp occlusal third up to the 15-min application groups of each bleaching gel. In the groups exposed to each concentration for 30 and 45 min, the number of inflammatory cells decreased along with the appearance of necrotic areas. After 30 days, reduction on the pulp chamber central area and enlargement of the tertiary dentin area were observed, without the detection of inflammation areas. Conclusion The rat model of extracoronal bleaching showed to be adequate for studies of bleaching protocols, as it was possible to observe alterations in the pulp tissues and tooth structure caused by different concentrations and application periods of bleaching agents.

Evaluation of an experimental rat model for comparative studies of bleaching agents

PubMed Central

CINTRA, Luciano Tavares Angelo; BENETTI, Francine; FERREIRA, Luciana Louzada; RAHAL, Vanessa; ERVOLINO, Edilson; JACINTO, Rogério de Castilho; GOMES, João Eduardo; BRISO, André Luiz Fraga

2016-01-01

ABSTRACT Dental materials in general are tested in different animal models prior to the clinical use in humans, except for bleaching agents. Objectives To evaluate an experimental rat model for comparative studies of bleaching agents, by investigating the influence of different concentrations and application times of H2O2 gel in the pulp tissue during in-office bleaching of rats’ vital teeth. Material and Methods The right and left maxillary molars of 50 Wistar rats were bleached with 20% and 35% H2O2 gels, respectively, for 5, 10, 15, 30, or 45 min (n=10 rats/group). Ten animals were untreated (control). The rats were killed after 2 or 30 days, and the maxillae were examined by light microscopy. Inflammation was evaluated through histomorphometric analysis with inflammatory cell count in the coronal and radicular thirds of the pulp. Fibroblasts were also counted. Scores were attributed to odontoblastic layer and vascular changes. Tertiary dentin area and pulp chamber central area were measured histomorphometrically. Data were compared by analysis of variance and Kruskal-Wallis test (p<0.05). Results After 2 days, the amount of inflammatory cells increased in the coronal pulp occlusal third up to the 15-min application groups of each bleaching gel. In the groups exposed to each concentration for 30 and 45 min, the number of inflammatory cells decreased along with the appearance of necrotic areas. After 30 days, reduction on the pulp chamber central area and enlargement of the tertiary dentin area were observed, without the detection of inflammation areas. Conclusion The rat model of extracoronal bleaching showed to be adequate for studies of bleaching protocols, as it was possible to observe alterations in the pulp tissues and tooth structure caused by different concentrations and application periods of bleaching agents. PMID:27119766

Changes to Glazed Dental Ceramic Shade, Roughness, and Microhardness after Bleaching and Simulated Brushing.

PubMed

Rodrigues, Carlos Roberto Teixeira; Turssi, Cecilia Pedroso; Amaral, Flávia Lucisano Botelho; Basting, Roberta Tarkany; França, Fabiana Mantovani Gomes

2017-09-05

To evaluate shade stability, surface roughness, microhardness, and compressive strength of a glazed feldspathic ceramic subjected to bleaching and simulated brushing. Eighty-eight glazed feldspathic ceramic specimens were made from microparticulate leucite and divided into eight groups (n = 10). The whitening products used were: Opalescence Trèswhite Supreme (Ultradent), Opalescence®\\ PF 15% (Ultradent), and Oral-B 3D White Whitestrips. All substances for whitening were used for 4 hours/day for a period of 14 days; the control group was not bleached. Next, half of the specimens were individually brushed. Microhardness and surface roughness data were subjected to three-way ANOVA and Tukey test. The diametrical tensile strength data were subjected to two-way ANOVA. The shade change data were analyzed using Kruskal-Wallis, Mann-Whitney, and the Student-Newman-Keuls test. The significance level was set at 5%. Glazed feldspathic ceramic surface microhardness was significantly affected by bleaching agents (p = 0.007). Initially, glazed ceramic microhardness was significantly higher than that observed after contact with the bleaching agents, whether or not brushing was performed. The specimens submitted to bleaching in preloaded trays presented lower surface roughness values after brushing (p = 0.037). The surface roughness was significantly lower in the brushed specimens (p = 0.044). The diametrical tensile strength was not significantly affected by the application of bleaching agents (p = 0.563) or by brushing (p = 0.477). When the specimens were brushed, however, shade change was significantly influenced by the bleaching agent used (p = 0.041). Bleaching agents associated with brushing cycles can alter surface properties and shade stability of glazed feldspathic ceramics, though such findings may not reflect the performance of unglazed feldspathic ceramics. © 2017 by the American College of Prosthodontists.

Effects of combining ozone and hydrogren peroxide on tooth bleaching: A clinical study.

PubMed

Al-Omiri, Mahmoud K; Hassan, Ra'ed S Abul; AlZarea, Bader K; Lynch, Edward

2016-10-01

The purpose of this study was to evaluate the efficiency of bleaching after combining ozone and 38% H2O2 in comparison to the sole use of 38% H2O2. Consecutive 26 participants (13 males and 13 females) were recruited into this study. They were randomly allocated into 2 groups (n=13 for each group). In group 1 (test group); the participants' upper anterior teeth were treated with 38% H2O2 for 20min then the teeth were exposed to ozone for 60s (healOzone(®) X4, KaVo Dental, Biberach, Germany). In group 2 (controls); the upper anterior teeth were treated with 20min of 38% H2O2 only. The shade of teeth was evaluated by recording the L* a* b* values and Vita Classic shades at study baseline and after bleaching in both groups. The statistically significant changes were set at P≤0.05. Tooth sensitivity and teeth shades were comparable between groups at study baseline (p>0.05). Controls reported more tooth sensitivity following bleaching (p<0.001). Teeth achieved better Vita shades, higher L* values (lighter shades), and lower a* and b* values (lighter shades) after bleaching in both groups (P≤0.05). However, teeth bleached with H2O2 and ozone achieved better Vita shades, higher L* values and lower a* values (lighter shades) than those bleached with H2O2 alone (p<0.001). Changes in b* values were not significantly different between groups. Bleaching with 38% H2O2 for 20min followed by 60s of ozone application would result in teeth with lighter shades than bleaching with 38% H2O2 alone. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of pH, bleaching agents, and acid etching on surface wear of bovine enamel.

PubMed

Soares, Ana Flávia; Bombonatti, Juliana Fraga Soares; Alencar, Marina Studart; Consolmagno, Elaine Cristina; Honório, Heitor Marques; Mondelli, Rafael Francisco Lia

2016-01-01

Development of new materials for tooth bleaching justifies the need for studies to evaluate the changes in the enamel surface caused by different bleaching protocols. The aim of this study was to evaluate the bovine dental enamel wear in function of different bleaching gel protocols, acid etching and pH variation. Sixty fragments of bovine teeth were cut, obtaining a control and test areas. In the test area, one half received etching followed by a bleaching gel application, and the other half, only the bleaching gel. The fragments were randomly divided into six groups (n=10), each one received one bleaching session with five hydrogen peroxide gel applications of 8 min, activated with hybrid light, diode laser/blue LED (HL) or diode laser/violet LED (VHL) (experimental): Control (C); 35% Total Blanc Office (TBO35HL); 35% Lase Peroxide Sensy (LPS35HL); 25% Lase Peroxide Sensy II (LPS25HL); 15% Lase Peroxide Lite (LPL15HL); and 10% hydrogen peroxide (experimental) (EXP10VHL). pH values were determined by a pHmeter at the initial and final time periods. Specimens were stored, subjected to simulated brushing cycles, and the superficial wear was determined (μm). ANOVA and Tukey´s tests were applied (α=0.05). The pH showed a slight decrease, except for Group LPL15HL. Group LPS25HL showed the highest degree of wear, with and without etching. There was a decrease from the initial to the final pH. Different bleaching gels were able to increase the surface wear values after simulated brushing. Acid etching before bleaching increased surface wear values in all groups.

Coral bleaching under unconventional scenarios of climate warming and ocean acidification

NASA Astrophysics Data System (ADS)

Kwiatkowski, Lester; Cox, Peter; Halloran, Paul R.; Mumby, Peter J.; Wiltshire, Andy J.

2015-08-01

Elevated sea surface temperatures have been shown to cause mass coral bleaching. Widespread bleaching, affecting >90% of global coral reefs and causing coral degradation, has been projected to occur by 2050 under all climate forcing pathways adopted by the IPCC for use within the Fifth Assessment Report. These pathways include an extremely ambitious pathway aimed to limit global mean temperature rise to 2 °C (ref. ; Representative Concentration Pathway 2.6--RCP2.6), which assumes full participation in emissions reductions by all countries, and even the possibility of negative emissions. The conclusions drawn from this body of work, which applied widely used algorithms to estimate coral bleaching, are that we must either accept that the loss of a large percentage of the world’s coral reefs is inevitable, or consider technological solutions to buy those reefs time until atmospheric CO2 concentrations can be reduced. Here we analyse the potential for geoengineering, through stratospheric aerosol-based solar radiation management (SRM), to reduce the extent of global coral bleaching relative to ambitious climate mitigation. Exploring the common criticism of geoengineering--that ocean acidification and its impacts will continue unabated--we focus on the sensitivity of results to the aragonite saturation state dependence of bleaching. We do not, however, address the additional detrimental impacts of ocean acidification on processes such as coral calcification that will further determine the benefit to corals of any SRM-based scenario. Despite the sensitivity of thermal bleaching thresholds to ocean acidification being uncertain, stabilizing radiative forcing at 2020 levels through SRM reduces the risk of global bleaching relative to RCP2.6 under all acidification-bleaching relationships analysed.

Evaluation of the effect of a home-bleaching agent on the surface characteristics of indirect esthetic restorative materials: part I--roughness.

PubMed

Torabi, Kianoosh; Rasaeipour, Sasan; Khaledi, Amir Alireza; Vojdani, Mahroo; Ghodsi, Safoura

2014-05-01

Pressing esthetic demands of good looking make people undergo bleaching procedures. However, the effect of bleaching agents on esthetic restorative materials with different surface preparations has been poorly studied. The aim of this study was to examine the effect of a homebleaching agent (carbamide peroxide: CP 38%) on the surface roughness of the polished fiber reinforced composite (FRC), overglazed, autoglazed, or polished ceramic samples. Twenty standardized cylindrical specimens were made of each of the following groups: over-glazed, autoglazed, polished porcelain and also FRC. The test specimens exposed to the CP 38%, 15 minutes, twice a day for 2 weeks according to the manufacturer's recommendation. Six samples from each group were selected randomly to form negative controls. Surface roughness measurements (Ra, micrometer) for baseline, test and control specimens were performed by use of a profilometer. Paired t-test, Mann-Whitney test, and Kruskal-Wallis test were used for statistical analyses. The data showed that bleaching with CP 38% significantly increased the surface roughness of all the test samples (p < 0.05). The type of surface preparation caused significant differences between the susceptibility of porcelain subgroups to bleaching (p < 0.05). The polished porcelain specimens showed the highest changes after bleaching. CP 38% significantly increases the surface roughness of the porcelains and FRC. The type of surface condition affects the amenability of the porcelain surface to the bleaching agent. Glazed porcelains were more resistant to roughness than the polished porcelains and also the composite. Roughening of porcelain and FRC occur following bleaching procedure. No special surface preparation of indirect esthetic restorative materials can completely preserve these materials from adverse effects of bleaching agents.

Marked annual coral bleaching resilience of an inshore patch reef in the Florida Keys: A nugget of hope, aberrance, or last man standing?

NASA Astrophysics Data System (ADS)

Gintert, Brooke E.; Manzello, Derek P.; Enochs, Ian C.; Kolodziej, Graham; Carlton, Renée; Gleason, Arthur C. R.; Gracias, Nuno

2018-06-01

Annual coral bleaching events, which are predicted to occur as early as the next decade in the Florida Keys, are expected to cause catastrophic coral mortality. Despite this, there is little field data on how Caribbean coral communities respond to annual thermal stress events. At Cheeca Rocks, an inshore patch reef near Islamorada, FL, the condition of 4234 coral colonies was followed over 2 yr of subsequent bleaching in 2014 and 2015, the two hottest summers on record for the Florida Keys. In 2014, this site experienced 7.7 degree heating weeks (DHW) and as a result 38.0% of corals bleached and an additional 36.6% were pale or partially bleached. In situ temperatures in summer of 2015 were even warmer, with the site experiencing 9.5 DHW. Despite the increased thermal stress in 2015, only 12.1% of corals were bleached in 2015, which was 3.1 times less than 2014. Partial mortality dropped from 17.6% of surveyed corals to 4.3% between 2014 and 2015, and total colony mortality declined from 3.4 to 1.9% between years. Total colony mortality was low over both years of coral bleaching with 94.7% of colonies surviving from 2014 to 2016. The reduction in bleaching severity and coral mortality associated with a second stronger thermal anomaly provides evidence that the response of Caribbean coral communities to annual bleaching is not strictly temperature dose dependent and that acclimatization responses may be possible even with short recovery periods. Whether the results from Cheeca Rocks represent an aberration or a true resilience potential is the subject of ongoing research.

Effect of acidity of in-office bleaching gels on tooth sensitivity and whitening: a two-center double-blind randomized clinical trial.

PubMed

Loguercio, A D; Servat, F; Stanislawczuk, R; Mena-Serrano, A; Rezende, M; Prieto, M V; Cereño, V; Rojas, M F; Ortega, K; Fernandez, E; Reis, A

2017-12-01

The study aimed to compare the tooth sensitivity (TS) and bleaching efficacy of two hydrogen peroxide gels with different pHs (acid pH [Pola Office, SDI] and the neutral pH [Pola Office+, SDI]) used for in-office bleaching. Fifty-four patients from Brazil and Chile, with right superior incisor darker than A2, were selected for this double-blind, split-mouth randomized trial. Teeth were bleached in two sessions, with 1-week interval. Each session had three applications of 8 min each, according to the manufacturer's instructions. The color changes were evaluated by subjective (Vita Classical and Vita Bleachedguide) and objective (Easy shade spectrophotometer) methods. Participants recorded TS with 0-10 visual analog scale. Color change in shade guide units (SGU) and ΔE was analyzed by Student's t test (α = 0.05). The absolute risk and intensity of TS were evaluated by McNemar's test and Wilcoxon-paired test, respectively (α = 0.05). All groups achieved the same level of whitening after 30 days of clinical evaluation. The use of a neutral in-office bleaching gel significantly decreases the absolute risk of TS (28%, 95% CI 18-41) and intensity of TS when compared to the acid bleaching gel (absolute risk of 50%, 95% CI 37-63). The use of a neutral in-office bleaching agent gel produced the same whitening degree than an acid bleaching gel but with reduced risk and intensity of tooth sensitivity. Clinicians should opt to use in-office bleaching with a neutral gel than an acid product because the former causes a significant lower risk and intensity of tooth sensitivity.

Effect of topical application of dipyrone on dental sensitivity reduction after in-office dental bleaching: A randomized, triple-blind multicenter clinical trial.

PubMed

Rezende, Márcia; Chemin, Kaprice; Vaez, Savil Costa; Peixoto, Aline Carvalho; Rabelo, Jéssica de Freitas; Braga, Stella Sueli Lourenço; Faria-E-Silva, André Luis; Silva, Gisele Rodrigues da; Soares, Carlos José; Loguercio, Alessandro D; Reis, Alessandra

2018-05-01

Tooth sensitivity commonly occurs during and immediately after dental bleaching. The authors conducted a trial to compare tooth sensitivity after in-office bleaching after the use of either a topical dipyrone or placebo gel. A split-mouth, triple-blind, randomized, multicenter clinical trial was conducted among 120 healthy adults having teeth that were shade A2 or darker. The facial tooth surfaces of the right or left sides of the maxillary arch of each patient were randomly assigned to receive either topical dipyrone or placebo gel before 2 in-office bleaching sessions (35% hydrogen peroxide) separated by 2 weeks. Visual analog and numerical rating scales were used to record tooth sensitivity during and up to 48 hours after bleaching. Tooth color change from baseline to 1 month after bleaching was measured with shade guide and spectrophotometer measures. The primary outcome variable was absolute risk of tooth sensitivity. An intention-to-treat analysis was used to analyze data from all patients who were randomly assigned to receive the dipyrone and placebo gels. No statically significant difference was found in the absolute risk of tooth sensitivity between the dipyrone and placebo gels (83% and 90%, respectively, P = .09; relative risk, 0.92; 95% confidence interval, 0.8 to 1.0). A whitening effect was observed in both groups with no statistically significant difference (P > .05) between them. No adverse effects were observed. Topical use of dipyrone gel before tooth bleaching, at the levels used in this study, did not reduce the risk or intensity of bleaching-induced tooth sensitivity. Topical application of dipyrone gel does not reduce bleaching-induced tooth sensitivity. Copyright © 2018 American Dental Association. Published by Elsevier Inc. All rights reserved.

IMPACT OF BLEACHING STRESS ON THE FUNCTION OF THE OXYGEN EVOLVING COMPLEX OF ZOOXANTHELLAE FROM SCLERACTINIAN CORALS(1).

PubMed

Hill, Ross; Ralph, Peter J

2008-04-01

Global climate change is leading to the rise of ocean temperatures and is triggering mass coral bleaching events on reefs around the world. The expulsion of the symbiotic dinoflagellate algae is believed to occur as a result of damage to the photosynthetic apparatus of these symbionts, although the specific site of initial impact is yet to be conclusively resolved. Here, the sensitivity of the oxygen evolving complex (OEC) to bleaching stress was studied as well as its natural variation between seasons. The artificial electron donor, diphenyl carbazide (DPC), was added to cultured, freshly isolated and expelled (bleaching treatments only) zooxanthellae suspensions. Chl a fluorescence and oxygen production measurements showed that upon addition of DPC, no restoration of diminished photochemical efficiency occurred under control or bleaching conditions. This result was consistent between 12 h and 5 d bleaching treatments on Pocilloporadamicornis, indicating that the OEC is not the primary site of damage, and that zooxanthellae expulsion from the host is a nonselective process with respect to the functioning of the OEC. Further experiments measuring fast induction curves (FICs) revealed that in both summer and winter, the temperature when OEC function was lost occurred between 7°C and 14°C above the sea surface temperature. FIC and oxygen production measurements of P. damicornis during exposure to bleaching stress demonstrated that the thermotolerance of the OEC increased above the temperature of the bleaching treatment over a 4 h period. This finding indicates that the OEC has the capacity to acclimate between seasons and remains functional at temperatures well above bleaching thresholds. © 2008 Phycological Society of America.

Immune defenses of healthy, bleached and diseased Montastraea faveolata during a natural bleaching event.

PubMed

Mydlarz, Laura D; Couch, Courtney S; Weil, Ernesto; Smith, Garriet; Harvell, C Drew

2009-11-16

One prominent hypothesis regarding climate change and scleractinian corals is that thermal stress compromises immune competence. To test this hypothesis we tracked how the immune defenses of bleached, apparently healthy and yellow band disease (YBD) diseased Montastraea faveolata colonies varied with natural thermal stress in southwestern Puerto Rico. Colonies were monitored for 21 mo from the peak of the bleaching event in October 2005 to August 2007. Since sea surface temperature was significantly higher in summer and fall 2005 than 2006, year of collection was used as a proxy for temperature stress, and colony fragments collected in 2005 were compared with those collected in 2006. Mortality rate was high (43% overall) and all colonies (except one) either died or became infected with YBD by August 2007. YBD-infected tissue did not bleach (i.e. expel zooxanthellae) during the 2005 bleaching event, even when healthy tissue of these colonies bleached. Immune activity was assayed by measuring prophenoloxidase (PPO), peroxidase (POX), lysozyme-like (LYS) and antibacterial (AB) activity. Immune activity was variable between all coral samples, but there was a significant elevation of PPO activity in bleached colonies collected in 2005 relative to apparently healthy and YBD-diseased corals in 2006. In YBD-diseased colonies, LYS and AB activity were elevated in both healthy and infected tissue, indicating a systemic response; activity levels in these colonies were higher compared to those that appeared healthy. In both these immune parameters, there was a trend for suppression of activity in corals that were bleached in 2005. These data, while complicated by between-genet variability, illustrate the complex interaction between disease and temperature stress on immune function.

Recirculation: A New Concept to Drive Innovation in Sustainable Product Design for Bio-Based Products.

PubMed

Sherwood, James; Clark, James H; Farmer, Thomas J; Herrero-Davila, Lorenzo; Moity, Laurianne

2016-12-29

Bio-based products are made from renewable materials, offering a promising basis for the production of sustainable chemicals, materials, and more complex articles. However, biomass is not a limitless resource or one without environmental and social impacts. Therefore, while it is important to use biomass and grow a bio-based economy, displacing the unsustainable petroleum basis of energy and chemical production, any resource must be used effectively to reduce waste. Standards have been developed to support the bio-based product market in order to achieve this aim. However, the design of bio-based products has not received the same level of attention. Reported here are the first steps towards the development of a framework of understanding which connects product design to resource efficiency. Research and development scientists and engineers are encouraged to think beyond simple functionality and associate value to the potential of materials in their primary use and beyond.

Ramie (Boehmeria nivea) decortication waste bio-briquette business model canvas with design thinking approach

NASA Astrophysics Data System (ADS)

Pahlavi, Ghifari Rezka; Purnomo, Dwi; Bunyamin, Anas; Wulandari, Asri Peni

2017-03-01

Ramie (Boehmeria nivea) is a plant that can produce fibers from its stem but in the production process, it still produces waste containing high lignin and cellulose. The high content of these substances can be used as bio-briquette raw material because they can produce carbon and can offer a business opportunity to establish bio-briquette industry. The purpose of this study is to obtain a ramie decortification waste bio-briquette business model because until now there is no bio-briquette has been made from ramie decortication waste as its raw material. This research uses descriptive analysis method with a design thinking approach. The result of this research shows that the business model canvas is designed based on consumer's experience when interacting with the product via customer journey tool in order to get the business model in accordance with customer expectations.

Reduction of timing jitter in a Q-Switched Nd:YAG laser by direct bleaching of a Cr4+:YAG saturable absorber.

PubMed

Cole, Brian; Goldberg, Lew; Trussell, C Ward; Hays, Alan; Schilling, Bradley W; McIntosh, Chris

2009-02-02

A method for optical triggering of a Q-switched Nd:YAG laser by direct bleaching of a Cr:YAG saturable absorber is described. This method involves the bleaching of a thin sheet of the saturable absorber from a direction orthogonal to the lasing axis using a single laser diode bar, where the Cr:YAG transmission increased from a non-bleached value of 47% to a bleached value of 63%. For steady state operation of a passively Q-switched laser (PRF=10 Hz), the pulse-to-pulse timing jitter showed approximately 12X reduction in standard deviation, from 241 nsec for free running operation to 20 nsec with optical triggering.

75 FR 5033 - Departmental Management; Public meeting on BioPreferredSM

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-01

...; Public meeting on BioPreferred\\SM\\ Complex Products and Assemblies Designation and Industry Training on... include: 1. Using BioPreferred tools to position your business to sell or increase sales to the Federal...: Ron Buckhalt, BioPreferred Manager, U.S. Department of Agriculture, Office of Procurement and Property...

75 FR 12492 - Departmental Management; Public Meeting on BioPreferredSM

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-16

...; Public Meeting on BioPreferred\\SM\\ Intermediate Material and Feedstock Product Designation AGENCY... after registering. FOR FURTHER INFORMATION CONTACT: Ron Buckhalt, BioPreferred Manager, U.S. Department... program together as the BioPreferred\\SM\\ Program. Due to the changes mandated by the 2008 Farm Bill, and...

Revolutionary Design for Astronaut Exploration — Beyond the Bio-Suit System

NASA Astrophysics Data System (ADS)

Newman, Dava J.; Canina, Marita; Trotti, Guillermo L.

2007-01-01

The Bio-Suit System is designed to revolutionize human space exploration by providing enhanced astronaut extravehicular activity (EVA) locomotion and performance based on the concepts of a `second skin' capability. The novel Bio-Suit concept provides an overall exploration system realized through symbiotic relationships between a suite of advanced technologies, creative design, human modeling and analysis, and new mission operations techniques. By working at the intersection of engineering, design, life sciences and operations, new emergent capabilities and interrelationships result for applications to space missions, medical rehabilitation, and extreme sports activities. In many respects, the Bio-Suit System mimics Nature (biomimetics). For example, the second skin is capable of augmenting our biological skin by providing mechanical counter-pressure. We have designed and tested prototypes that prove mechanical counter-pressure feasibility. The `epidermis' of our second skin suit is patterned from 3D laser scans that incorporate human skin strain field maps for maximum mobility and natural movements, while requiring minimum energy expenditure for exploration tasks. We provide a technology roadmap for future design, pressure production and technology investments for the Bio-Suit System. Woven into the second skin are active materials to enhance human performance as well as to provide necessary performance metrics (i.e., energy expenditure). Wearable technologies will be embedded throughout the Bio-Suit System to place the explorer in an information-rich environment enabling real-time mission planning, prediction, and visualization. The Bio-Suit System concept augments human capabilities by coupling human and robotic abilities into a hybrid of the two, to the point where the explorer is hardly aware of the boundary between innate human performance and robotic activities.

Bleaching augments lipid peroxidation products in pistachio oil and its cytotoxicity

USDA-ARS?s Scientific Manuscript database

Pistachio consumption is associated with reductions in serum cholesterol and oxidative stress due to their constituents of unsaturated fats, phytosterols, fiber, and antioxidants. Bleaching has been applied to whiten nut shells for antifungal and cosmetic purposes. However, the impact of bleaching o...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goreau, T.J.; Hayes, R.L.; Strong, A.

Global spatio-temporal patterns of mass coral reef bleaching during the first half of the 1990s continued to show the strong temperature correlations which first became established in the 1980s. Satellite sea surface temperature data and field observations were used to track thermal bleaching events in real time. Most bleaching events followed warm season sea surface temperature anomalies of around +1 degree celsius above historical means. Global bleaching patterns appear to have been strongly affected by worldwide cooling which followed eruption of Mount Pinatubo in June 1991. High water temperatures and mass coral reef bleaching took place in the Caribbean, Indianmore » Ocean, and South Pacific in 1991, but there were few thermal anomalies or bleaching events in 1992 and 1993, years which were markedly cooler worldwide. Following the settling of Mount Pinatubo aerosols and resumption of global warming trends, extensive ocean thermal hot spots and bleaching events resumed in the South Pacific, South Atlantic, and Indian Oceans in 1994. Bleaching again took place in hot spots in the Indian Ocean and Caribbean in 1995, and in the South Atlantic, Caribbean, South Pacific, North Pacific, and Persian Gulf in 1996. Coral reefs worldwide are now very close to their upper temperature tolerance limits. This sensitivity, and the fact that the warmest ecosystems have no source of immigrant species pre-adapted to warmer conditions, may make coral reef ecosystems the first to be severely impacted if global temperatures and sea levels remain at current values or increase further.« less

Effects of modeled tropical sea surface temperature variability on coral reef bleaching predictions

NASA Astrophysics Data System (ADS)

Van Hooidonk, R. J.

2011-12-01

Future widespread coral bleaching and subsequent mortality has been projected with sea surface temperature (SST) data from global, coupled ocean-atmosphere general circulation models (GCMs). While these models possess fidelity in reproducing many aspects of climate, they vary in their ability to correctly capture such parameters as the tropical ocean seasonal cycle and El Niño Southern Oscillation (ENSO) variability. These model weaknesses likely reduce the skill of coral bleaching predictions, but little attention has been paid to the important issue of understanding potential errors and biases, the interaction of these biases with trends and their propagation in predictions. To analyze the relative importance of various types of model errors and biases on coral reef bleaching predictive skill, various intra- and inter-annual frequency bands of observed SSTs were replaced with those frequencies from GCMs 20th century simulations to be included in the Intergovernmental Panel on Climate Change (IPCC) 5th assessment report. Subsequent thermal stress was calculated and predictions of bleaching were made. These predictions were compared with observations of coral bleaching in the period 1982-2007 to calculate skill using an objective measure of forecast quality, the Peirce Skill Score (PSS). This methodology will identify frequency bands that are important to predicting coral bleaching and it will highlight deficiencies in these bands in models. The methodology we describe can be used to improve future climate model derived predictions of coral reef bleaching and it can be used to better characterize the errors and uncertainty in predictions.

Spectroscopic And Electrochemical Studies Of Electrochromic Hydrated Nickel Oxide Films

NASA Astrophysics Data System (ADS)

Yu, P. C.; Nazri, G.; Lampert, C. M.

1986-09-01

The electrochrcrnic properties of hydrated nickel oxide thin films electrochemically deposited by anodization onto doped tin oxide-coated glass have been studied by transmittance measurements, cyclic voltammetry, Fourier-transform infrared spectroscopy, and ion-backscattering spectrometry. The spectral transmittance is reported for films switched in both the bleached and colored states. The photopic transmittance (Tp) can be switched from T (bleached) = 0.77 to T (colored) = 0.21, and the solar transmittance (Ts) can be switched from Ts(bleached) = 0.73 to TS (colored) = 0.35. Also reported is the near-infrared transmittance (TNIR)which was found to switch fran T N,IR (bleached) = 0.72 to TNIR (colored) = 0.55. The bleached condition is noted to have very low solar absorption in both the visible and solar regions. Ion-backscattering spectrometry was performed on the hydrated nickel oxide film, yielding a camposition of Ni01.0 (dehydrated) and a film thickness of 125 A. Cyclic voltammetry showed that, for films in the bleached or colored state, the reversible reaction is Ni(0H), = NiOOH + H+ + e . Voltammnetry also showed that the switching of the film is controlled by the diffusion or protons, where OH plays a role in the reaction mechanism. Analysis of the hydrated nickel-oxide thin films by Fourier-transform infrared spectroscopy revealed that both the bleached and colored states contain lattice water and hydroxyl groups. The surface hydroxyl groups play an important role in the coloration and bleaching of the anodically deposited nickel oxide thin films.

The effect of home-use and in-office bleaching treatments combined with experimental desensitizing agents on enamel and dentin

PubMed Central

Pintado-Palomino, Karen; Tirapelli, Camila

2015-01-01

Objective: This study aimed to evaluate in vitro the effect of formulations containing Biosilicate to treat enamel and dentin bovine samples exposed to dental bleaching agents. Materials and Methods: On enamel and dentin bleached with commercial gels containing 16% carbamide peroxide (CP) (14 days/4 h) or 35% hydrogen peroxide (single session/45 min), desensitizing dentifrices (Sensodyne®; experimental dentifrice of Biosilicate®; Odontis RX®; Sorriso®) were applied along 14 days and desensitizing pastes (Biosilicate®/water 1:1; Dessensebilize NanoP®; Bioglass type 45S5/water 1:1) were applied on days 1, 3, 7, 10 and 14. Distilled water was the control. Microhardness (MH) and roughness measurements were the variables measured on the samples before and after the treatments. Student's t-test analyzed differences before and after the treatments. Two-way analysis of variance and post-hoc Tukey test analyzed differences among the factors desensitizing, bleaching agents and substrate. Results: Tukey test showed no differences in roughness for both bleaching treatments and among the desensitizing agents (P > 0.05). Differences in MH appeared on enamel treated with in-home bleaching when control group (lower values) was compared with Sensodyne, Biosilicate dentifrice, Biosilicate paste, and Bioglass paste (higher values). Comparisons between desensitizing agents on dentin treated with both bleaching gels showed no statistical differences. Conclusions: The effect of formulations containing Biosilicate (Biosilicate dentifrice and paste) was significant in the MH of enamel bleached with 16% CP. PMID:25713487

Evaluation of the Effect of Different Laser Activated Bleaching Methods on Enamel Susceptibility to Caries; An In Vitro Mode.

PubMed

Ashnagar, Sajjad; Monzavi, Abbas; Abbasi, Mehdi; Aghajani, Mahdi; Chiniforush, Nasim

2017-01-01

Introduction: Today, bleaching is a routine noninvasive alternative for treatment of discolored teeth. The aim of this study was to determine whether conventional or laser activated bleaching predispose teeth to develop caries or not. Methods: Sixty human molars were mounted on acrylic cylinders and their Knoop microhardness (KHN) as well as DIAGNOdent (DD) values were recorded. They were divided into 4 experimental groups; G1) conventional bleaching with 40% hydrogen peroxide gel, G2) Diode laser assisted bleaching with same gel, G3) Nd:YAG laser assisted bleaching with the same gel, G4) control group. After bleaching, all samples were subjected to a three day pH cycling regimen and then, KHN and DD values were measured. Results: All groups had significant reduction in KHN values. It seems that there is no statistically meaningful difference between changes in enamel microhardness of the sample groups and all groups have changed in a similar amount. Reduction of DD scores were significant in Diode laser and conventional groups, however changes in Nd:YAG laser and control groups were not significant. Changes in DD values have followed a similar pattern among groups, except in G1- G4 and G2-G4 couples. Conventional and diode laser groups had a meaningful difference in reduction of DD values in comparison with the control group. Conclusion: It can be concluded that bleaching whether conventional or laser activated, does not make teeth vulnerable to develop carious lesions.

Photobiomodulation in the Prevention of Tooth Sensitivity Caused by In-Office Dental Bleaching. A Randomized Placebo Preliminary Study.

PubMed

Calheiros, Andrea Paiva Corsetti; Moreira, Maria Stella; Gonçalves, Flávia; Aranha, Ana Cecília Correa; Cunha, Sandra Ribeiro; Steiner-Oliveira, Carolina; Eduardo, Carlos de Paula; Ramalho, Karen Müller

2017-08-01

Analyze the effect of photobiomodulation in the prevention of tooth sensitivity after in-office dental bleaching. Tooth sensitivity is a common clinical consequence of dental bleaching. Therapies for prevention of sensitivity have been investigated in literature. This study was developed as a randomized, placebo blind clinical trial. Fifty patients were selected (n = 10) and randomly divided into five groups: (1) control, (2) placebo, (3) laser before bleaching, (4) laser after bleaching, and (5) laser before and after bleaching. Irradiation was performed perpendicularly, in contact, on each tooth during 10 sec per point in two points. The first point was positioned in the middle of the tooth crown and the second in the periapical region. Photobiomodulation was applied using the following parameters: 780 nm, 40 mW, 10 J/cm 2 , 0.4 J per point. Pain was analyzed before, immediately after, and seven subsequent days after bleaching. Patients were instructed to report pain using the scale: 0 = no tooth sensitivity, 1 = gentle sensitivity, 2 = moderate sensitivity, 3 = severe sensitivity. There were no statistical differences between groups at any time (p > 0.05). More studies, with others parameters and different methods of tooth sensitivity analysis, should be performed to complement the results found. Within the limitation of the present study, the laser parameters of photobiomodulation tested in the present study were not efficient in preventing tooth sensitivity after in-office bleaching.

Clinical and Spectrophotometric Evaluation of LED and Laser Activated Teeth Bleaching

PubMed Central

Lo Giudice, R.; Pantaleo, G.; Lizio, A.; Romeo, U.; Castiello, G.; Spagnuolo, G.; Giudice, G. Lo

2016-01-01

Background: Auxiliary power sources (LED and laser) are used in in-office teeth bleaching techniques to accelerate the redox reaction of the whitening gel to increase ease of use, to improve comfort and safety, and to decrease the procedure time. Objective: The aim this study is to evaluate the efficiency of the teeth whitening procedures performed with hydrogen peroxide and carbamide peroxide, LED or Laser activated. Method: 18 patients, affected by exogenous dyschromia, were treated with a bleaching agent composed by 35% hydrogen peroxide and 10% carbamide peroxide. They were divided into two groups: in the first group the bleaching agent was activated by a LED lamp; in the second group it was activated by a Laser diode lamp. Both groups were subjected to 3 bleaching cycle of 15’ each. The chromatic evaluations were performed before and after one week from the treatment, using a chromatic scale and a spectrophotometer. The mean value of pre, post bleaching and follow-up were analyzed using a T-test, with results statistically significant for P<0,05. Results: Results showed that the variations in brightness, chroma and hue are significantly influenced by the interaction between the whitening agent and the original colour of the teeth. Laser-activation has marginally improved the bleaching effectiveness. All patients treated with laser activation complained an increase in dental sensitivity. Conclusion: The use of laser-activating systems did not improve the efficacy of bleaching. PMID:27386010

Evaluation of cotton-fabric bleaching using hydrogen peroxide and Blue LED

NASA Astrophysics Data System (ADS)

de Oliveira, Bruno P.; Moriyama, Lilian T.; Bagnato, Vanderlei S.

2015-06-01

The raw cotton production requires multiple steps being one of them the removal of impurities acquired during previous processes. This procedure is widely used by textile industries around the world and is called bleaching. The raw cotton is composed by cellulosic and non-cellulosic materials like waxes, pectins and oils, which are responsible for its characteristic yellowish color. The bleaching process aims to remove the non-cellulosic materials concentration in the fabric, increasing its whiteness degree. The most used bleaching method utilizes a bath in an alkali solution of hydrogen peroxide, stabilizers and buffer solutions under high temperature. In the present study we evaluated the possibility of using a blue illumination for the bleaching process. We used blue LEDs (450 nm) to illuminate an acid hydrogen peroxide solution at room temperature. The samples treated by this method were compared with the conventional bleaching process through a colorimetric analysis and by a multiple comparison visual inspection by volunteers. The samples were also studied by a tensile test in order to verify the integrity of the cloth after bleaching. The results of fabric visual inspection and colorimetric analysis showed a small advantage for the sample treated by the standard method. The tensile test showed an increasing on the yield strength of the cloth after blue light bleaching. The presented method has great applicability potential due to the similar results compared to the standard method, with relative low cost and reduced production of chemical waste.

Differential gene expression during thermal stress and bleaching in the Caribbean coral Montastraea faveolata.

PubMed

DeSalvo, M K; Voolstra, C R; Sunagawa, S; Schwarz, J A; Stillman, J H; Coffroth, M A; Szmant, A M; Medina, M

2008-09-01

The declining health of coral reefs worldwide is likely to intensify in response to continued anthropogenic disturbance from coastal development, pollution, and climate change. In response to these stresses, reef-building corals may exhibit bleaching, which marks the breakdown in symbiosis between coral and zooxanthellae. Mass coral bleaching due to elevated water temperature can devastate coral reefs on a large geographical scale. In order to understand the molecular and cellular basis of bleaching in corals, we have measured gene expression changes associated with thermal stress and bleaching using a complementary DNA microarray containing 1310 genes of the Caribbean coral Montastraea faveolata. In a first experiment, we identified differentially expressed genes by comparing experimentally bleached M. faveolata fragments to control non-heat-stressed fragments. In a second experiment, we identified differentially expressed genes during a time course experiment with four time points across 9 days. Results suggest that thermal stress and bleaching in M. faveolata affect the following processes: oxidative stress, Ca(2+) homeostasis, cytoskeletal organization, cell death, calcification, metabolism, protein synthesis, heat shock protein activity, and transposon activity. These results represent the first medium-scale transcriptomic study focused on revealing the cellular foundation of thermal stress-induced coral bleaching. We postulate that oxidative stress in thermal-stressed corals causes a disruption of Ca(2+) homeostasis, which in turn leads to cytoskeletal and cell adhesion changes, decreased calcification, and the initiation of cell death via apoptosis and necrosis.

SynBioSS designer: a web-based tool for the automated generation of kinetic models for synthetic biological constructs

PubMed Central

Weeding, Emma; Houle, Jason

2010-01-01

Modeling tools can play an important role in synthetic biology the same way modeling helps in other engineering disciplines: simulations can quickly probe mechanisms and provide a clear picture of how different components influence the behavior of the whole. We present a brief review of available tools and present SynBioSS Designer. The Synthetic Biology Software Suite (SynBioSS) is used for the generation, storing, retrieval and quantitative simulation of synthetic biological networks. SynBioSS consists of three distinct components: the Desktop Simulator, the Wiki, and the Designer. SynBioSS Designer takes as input molecular parts involved in gene expression and regulation (e.g. promoters, transcription factors, ribosome binding sites, etc.), and automatically generates complete networks of reactions that represent transcription, translation, regulation, induction and degradation of those parts. Effectively, Designer uses DNA sequences as input and generates networks of biomolecular reactions as output. In this paper we describe how Designer uses universal principles of molecular biology to generate models of any arbitrary synthetic biological system. These models are useful as they explain biological phenotypic complexity in mechanistic terms. In turn, such mechanistic explanations can assist in designing synthetic biological systems. We also discuss, giving practical guidance to users, how Designer interfaces with the Registry of Standard Biological Parts, the de facto compendium of parts used in synthetic biology applications. PMID:20639523

Bio-microfluidics: biomaterials and biomimetic designs.

PubMed

Domachuk, Peter; Tsioris, Konstantinos; Omenetto, Fiorenzo G; Kaplan, David L

2010-01-12

Bio-microfluidics applies biomaterials and biologically inspired structural designs (biomimetics) to microfluidic devices. Microfluidics, the techniques for constraining fluids on the micrometer and sub-micrometer scale, offer applications ranging from lab-on-a-chip to optofluidics. Despite this wealth of applications, the design of typical microfluidic devices imparts relatively simple, laminar behavior on fluids and is realized using materials and techniques from silicon planar fabrication. On the other hand, highly complex microfluidic behavior is commonplace in nature, where fluids with nonlinear rheology flow through chaotic vasculature composed from a range of biopolymers. In this Review, the current state of bio-microfluidic materials, designs and applications are examined. Biopolymers enable bio-microfluidic devices with versatile functionalization chemistries, flexibility in fabrication, and biocompatibility in vitro and in vivo. Polymeric materials such as alginate, collagen, chitosan, and silk are being explored as bulk and film materials for bio-microfluidics. Hydrogels offer options for mechanically functional devices for microfluidic systems such as self-regulating valves, microlens arrays and drug release systems, vital for integrated bio-microfluidic devices. These devices including growth factor gradients to study cell responses, blood analysis, biomimetic capillary designs, and blood vessel tissue culture systems, as some recent examples of inroads in the field that should lead the way in a new generation of microfluidic devices for bio-related needs and applications. Perhaps one of the most intriguing directions for the future will be fully implantable microfluidic devices that will also integrate with existing vasculature and slowly degrade to fully recapitulate native tissue structure and function, yet serve critical interim functions, such as tissue maintenance, drug release, mechanical support, and cell delivery.

Project Overview: A Reef Manager’s Guide to Coral Bleaching

EPA Science Inventory

The purpose of this report is to provide the latest scientific knowledge and discuss available management options to assist local and regional managers in responding effectively to mass coral bleaching events.

Background

Comparing Environmental Influences on Coral Bleaching Across and within Species using Clustered Binomial Regression

EPA Science Inventory

Differential susceptibility among reef-building coral species can lead to community shifts and loss of diversity as a result of temperature-induced mass bleaching events. However, the influence of the local environment on species-specific bleaching susceptibilities has not been ...

Knowledge of the risks associated with skin bleaching among Togolese users.

PubMed

Kpanake, L; Sastre, M T Munoz; Sorum, P C; Mullet, E

2008-01-01

We examined the extent of Togolese users' knowledge of the health risks associated with the regular use of bleaching agents. A massive underestimation of some of the main risks was discovered. The more frequent the use of bleaching agents, the higher the underestimation.

Expanding the utility of the Agricultural Research Service (ARS) process bleaching

USDA-ARS?s Scientific Manuscript database

The ARS Process for bleaching, biopolishing, and shrinkproofing wool is a novel alternative to chlorination and conventional bleaching. Consumer acceptance of domestic machine-washable, comfortable wool which can be worn next to the skin will lead to niche-market- potential and competitive, increas...

BioNetFit: a fitting tool compatible with BioNetGen, NFsim and distributed computing environments

DOE PAGES

Thomas, Brandon R.; Chylek, Lily A.; Colvin, Joshua; ...

2015-11-09

Rule-based models are analyzed with specialized simulators, such as those provided by the BioNetGen and NFsim open-source software packages. Here in this paper, we present BioNetFit, a general-purpose fitting tool that is compatible with BioNetGen and NFsim. BioNetFit is designed to take advantage of distributed computing resources. This feature facilitates fitting (i.e. optimization of parameter values for consistency with data) when simulations are computationally expensive.

Effects of a New Bleaching Gel on Tooth Whitening

DTIC Science & Technology

2016-05-17

that claims "wow’’ results and permanent whiteness unaffected by consumption of coffee, tea, or red wine with low to no sensitivity. KOR has also...bleaching to result in greater lightness {delta L *)than Home bleaching, suggesting no overall benefit from either technique. Two recent clinical

Effect of a New Bleaching Gel on Tooth Whitening

DTIC Science & Technology

2016-05-12

that claims “wow” results and permanent whiteness unaffected by consumption of coffee, tea, or red wine with low to no sensitivity. KöR has also...tendency for Combined bleaching to result in greater lightness (delta L*) than Home bleaching, suggesting no overall benefit from either technique

40 CFR 430.22 - Effluent limitations representing the degree of effluent reduction attainable by the application...

Code of Federal Regulations, 2010 CFR

2010-07-01

... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS THE PULP, PAPER, AND PAPERBOARD POINT SOURCE CATEGORY Bleached... [BPT effluent limitations for bleached kraft facilities where market pulp is produced] Pollutant or... effluent limitations for bleached kraft facilities where paperboard, coarse paper, and tissue paper are...

40 CFR 63.455 - Reporting requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) or a bleaching system specified in § 63.440(d)(3)(ii) shall submit, with the initial notification... modifications during the 2-year period. (c) The owner or operator of each bleaching system complying with § 63... that the daily application rates of chlorine and hypochlorite for that bleaching system have not...

40 CFR 430.26 - Pretreatment standards for existing sources (PSES).

Code of Federal Regulations, 2010 CFR

2010-07-01

...) EFFLUENT GUIDELINES AND STANDARDS THE PULP, PAPER, AND PAPERBOARD POINT SOURCE CATEGORY Bleached Papergrade... it uses exclusively TCF bleaching processes at that fiber line. These pretreatment standards must be... report submitted under 40 CFR 403.12(b), (d), or (e) that it uses exclusively TCF bleaching processes at...

INDICATORS OF UV EXPOSURE IN CORALS AND THEIR RELEVANCE TO GLOBAL CLIMATE CHANGE AND CORAL BLEACHING

EPA Science Inventory

A compelling aspect of the deterioration of coral reefs is the phenomenon of coral bleaching. Through interactions with other factors such as sedimentation, pollution, and bacterial infection, bleaching can impact large areas of a reef with limited recovery, and it might be induc...

Correlation of Coral Bleaching Events and Remotely-Sensed Sea Surface Temperatures

DTIC Science & Technology

1994-05-19

water column. Diving on the reefs, they found significant tracts of bleached corals, zoanthids , gorgonians, and sea anemones (Bunckley-Williams and... zoanthids between May and July 1988 on shallow lagoonal reefs and rim margin reefs was the first indication of any sort of bleaching event at Bermuda

FRAP Analysis: Accounting for Bleaching during Image Capture

PubMed Central

Wu, Jun; Shekhar, Nandini; Lele, Pushkar P.; Lele, Tanmay P.

2012-01-01

The analysis of Fluorescence Recovery After Photobleaching (FRAP) experiments involves mathematical modeling of the fluorescence recovery process. An important feature of FRAP experiments that tends to be ignored in the modeling is that there can be a significant loss of fluorescence due to bleaching during image capture. In this paper, we explicitly include the effects of bleaching during image capture in the model for the recovery process, instead of correcting for the effects of bleaching using reference measurements. Using experimental examples, we demonstrate the usefulness of such an approach in FRAP analysis. PMID:22912750

Manganese peroxidase, produced by Trametes versicolor during pulp bleaching, demethylates and delignifies kraft pulp

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paice, M.G.; Reid, I.D.; Bourbonnais, R.

1993-01-01

The white rot fungus Trametes (Coriolus) versicolor delignifies and bleaches kraft pulp. However, the process is slow compared with chemical bleaching and the cellulose is also attacked. This study attempts to determine the enzymology of fungal delignification and then applies the relevant enzymes directly to the pulp. Lignin peroxidase and manganese peroxidase (MnP) have both been implicated in lignin biodegradations. However, the researchers show that MnP is the critical enzyme. It is produced by bleaching cultures of T. versicolor; its peak production occurs at the same time as the maximum rate of fungal culture bleaching, and the manganese-and peroxide-dependent demethylationmore » and delignification of kraft pulp occurs in vitro. 50 refs., 4 figs., 7 tabs.« less

Coral recovery in the central Maldives archipelago since the last major mass-bleaching, in 1998

NASA Astrophysics Data System (ADS)

Pisapia, C.; Burn, D.; Yoosuf, R.; Najeeb, A.; Anderson, K. D.; Pratchett, M. S.

2016-10-01

Increasing frequency and severity of disturbances is causing global degradation of coral reef ecosystems. This study examined temporal changes in live coral cover and coral composition in the central Maldives from 1997 to 2016, encompassing two bleaching events, a tsunami, and an outbreak of Acanthaster planci. We also examined the contemporary size structure for five dominant coral taxa (tabular Acropora, Acropora muricata, Acropora humilis, Pocillopora spp, and massive Porites). Total coral cover increased throughout the study period, with marked increases following the 1998 mass-bleaching. The relative abundance of key genera has changed through time, where Acropora and Pocillopora (which are highly susceptible to bleaching) were under-represented following 1998 mass-bleaching but increased until outbreaks of A. planci in 2015. The contemporary size-structure for all coral taxa was dominated by larger colonies with peaked distributions suggesting that recent disturbances had a disproportionate impact on smaller colonies, or that recruitment is currently limited. This may suggest that coral resilience has been compromised by recent disturbances, and further bleaching (expected in 2016) could lead to highly protracted recovery times. We showed that Maldivian reefs recovered following the 1998 mass-bleaching event, but it took up to a decade, and ongoing disturbances may be eroding reef resilience.

Coral recovery in the central Maldives archipelago since the last major mass-bleaching, in 1998.

PubMed

Pisapia, C; Burn, D; Yoosuf, R; Najeeb, A; Anderson, K D; Pratchett, M S

2016-10-03

Increasing frequency and severity of disturbances is causing global degradation of coral reef ecosystems. This study examined temporal changes in live coral cover and coral composition in the central Maldives from 1997 to 2016, encompassing two bleaching events, a tsunami, and an outbreak of Acanthaster planci. We also examined the contemporary size structure for five dominant coral taxa (tabular Acropora, Acropora muricata, Acropora humilis, Pocillopora spp, and massive Porites). Total coral cover increased throughout the study period, with marked increases following the 1998 mass-bleaching. The relative abundance of key genera has changed through time, where Acropora and Pocillopora (which are highly susceptible to bleaching) were under-represented following 1998 mass-bleaching but increased until outbreaks of A. planci in 2015. The contemporary size-structure for all coral taxa was dominated by larger colonies with peaked distributions suggesting that recent disturbances had a disproportionate impact on smaller colonies, or that recruitment is currently limited. This may suggest that coral resilience has been compromised by recent disturbances, and further bleaching (expected in 2016) could lead to highly protracted recovery times. We showed that Maldivian reefs recovered following the 1998 mass-bleaching event, but it took up to a decade, and ongoing disturbances may be eroding reef resilience.

Coral recovery in the central Maldives archipelago since the last major mass-bleaching, in 1998

PubMed Central

Pisapia, C.; Burn, D.; Yoosuf, R.; Najeeb, A.; Anderson, K. D.; Pratchett, M. S.

2016-01-01

Increasing frequency and severity of disturbances is causing global degradation of coral reef ecosystems. This study examined temporal changes in live coral cover and coral composition in the central Maldives from 1997 to 2016, encompassing two bleaching events, a tsunami, and an outbreak of Acanthaster planci. We also examined the contemporary size structure for five dominant coral taxa (tabular Acropora, Acropora muricata, Acropora humilis, Pocillopora spp, and massive Porites). Total coral cover increased throughout the study period, with marked increases following the 1998 mass-bleaching. The relative abundance of key genera has changed through time, where Acropora and Pocillopora (which are highly susceptible to bleaching) were under-represented following 1998 mass-bleaching but increased until outbreaks of A. planci in 2015. The contemporary size-structure for all coral taxa was dominated by larger colonies with peaked distributions suggesting that recent disturbances had a disproportionate impact on smaller colonies, or that recruitment is currently limited. This may suggest that coral resilience has been compromised by recent disturbances, and further bleaching (expected in 2016) could lead to highly protracted recovery times. We showed that Maldivian reefs recovered following the 1998 mass-bleaching event, but it took up to a decade, and ongoing disturbances may be eroding reef resilience. PMID:27694823

The effect of cold-light-activated bleaching treatment on enamel surfaces in vitro

PubMed Central

Shi, Xin-Chang; Ma, He; Zhou, Jing-Lin; Li, Wei

2012-01-01

This in vitro study aims to evaluate the crystal and surface microstructure of dental enamel after cold-light bleaching treatment. Twelve sound human premolars were cross-split into four specimens, namely, mesio-buccal (Group LP), disto-buccal (Group P), mesio-lingual (Group NP) and disto-lingual (Group L) specimens. These four groups were treated using the standard cold-light bleaching procedure, a bleaching agent, a peroxide-free bleaching agent and cold-light, respectively. Before and after treatment, all specimens were analyzed by high-resolution, micro-area X-ray diffraction and scanning electron microscopy. Using a spectrometer, tooth color of all specimens was measured before and after treatment. The phase of the enamel crystals was identified as hydroxyapatite and carbonated hydroxyapatite. After treatment, specimens in Groups LP and P showed significantly weaker X-ray diffraction peaks, significant reduction in crystal size and crystallinity, significant increase in L* but decrease in a* and b*, and obvious alterations in the surface morphology. However, specimens in Groups NP and L did not show any significant changes. The cold-light bleaching treatment leads to demineralization in the enamel surface. The acidic peroxide-containing bleaching agent was the major cause of demineralization, whereas cold-light did not exhibit significant increase or decrease effect on this demineralization. PMID:23258380

The potential of low-power laser for reducing dental sensitivity after in-office bleaching: a case report.

PubMed

Mayer-Santos, Eric; Anhesini, Brunna Haddad; Shimokawa, Carlos Alberto Kenji; Aranha, Ana Cecília Corrêa; Eduardo, Carlos Paula; de Freitas, Patricia Moreira

2017-01-01

Postoperative sensitivity is one of the most common side effects of in-office bleaching with hydrogen peroxide. Laser phototherapy (LPT) has been suggested as an adjunctive treatment to prevent or minimize tooth sensitivity. This case report aimed to verify the efficacy of LPT in the reduction of sensitivity after in-office bleaching. Tooth bleaching was performed with 35% hydrogen peroxide activated with a hybrid LED-laser device. Immediately after the bleaching treatment, the patient reported dental sensitivity, as measured with a visual analog scale (VAS). To reduce sensitivity, LPT was applied with a 780-nm laser using the following parameters: 70 mW, exposure time of 10 seconds per point of irradiation (middle region of the buccal surfaces of each compromised tooth) in contact mode, energy of 1 J per point. Immediately after LPT, the patient reported a substantially lower level of pain on the VAS. Twenty-four hours after bleaching, the score on the VAS indicated that sensitivity levels had rebounded, and the patient received additional LPT. After 48 hours, the patient reported no dental sensitivity. The results in this patient indicated that irradiation with an infrared low-power laser substantially reduced dental pain generated by bleaching, suggesting that LPT should be considered as an auxiliary method to reduce postbleaching tooth sensitivity.

Trade-offs in disease and bleaching susceptibility among two color morphs of the Hawaiian reef coral, Montipora capitata

NASA Astrophysics Data System (ADS)

Shore-Maggio, Amanda; Callahan, Sean M.; Aeby, Greta S.

2018-06-01

Two threats impacting coral reefs are bleaching and disease, and differential susceptibility to both exists among and within coral taxa. Bleaching resistance is commonly linked to the clade of endosymbiotic Symbiodinium, but may come at a cost to other biological traits. Montipora capitata is an Indo-Pacific reef-building coral with two color morphs, red and orange, which harbor different clades of Symbiodinium. We explored whether these color morphs displayed differences in bleaching/disease susceptibility and other biological traits (growth rate, reproductive output, and lipid content). We found a trade-off between disease and bleaching susceptibility. The orange morph had significantly higher disease prevalence, whereas the red morph had significantly higher bleaching prevalence. Thermal stress experiments found that bleaching and loss of photochemical efficiency occurred significantly faster in the red morph, but at normal temperatures, the red morph had a significantly higher growth rate. Higher abundance of the red morph in the field suggests that disease resistance is a more successful strategy in the absence of thermal stress events. The orange morph may better tolerate increases in sea temperatures, but may not persist due to decreased growth rate and increased disease susceptibility. Trade-offs in response to stressors highlight the need to consider local and global threats to coral reefs.

[High school student and skin bleaching in Cameroon].

PubMed

Mayoughouo Mouliom, Adeline; Wamba, André

2017-04-27

Introduction: Skin bleaching is a common practice in Africa, particularly in Cameroon. Studies show that it represents a danger for health, in terms of a demonstrated increased risk of dermatological diseases. However, increasing numbers of people are using skin bleaching in African cities, despite the fact that they are sometimes aware of the risk. This study proposed to transform the knowledge and perceptions of skin bleaching practices into educational strategies that can be used both by health professionals and educators. These strategies can also be used as preventive measures against skin bleaching among young schoolgirls. Methods: Data collection was based on a qualitative approach, in the form of a focus group discussion attended by 40 girls aged between 14 and 20 years, selected by convenient random sampling. Results: The results indicated that girls have an approximate knowledge about the consequences of skin bleaching on their health. On the contrary, they have a good knowledge about prevention, which can be used to develop a prevention strategy in order to reduce or eradicate skin bleaching, by educational awareness campaigns Conclusion: These elements can be used as a basis for better prevention and health promotion in schools; so that students adopt healthy behaviours and to prevent those students at risk.

Coral bleaching--capacity for acclimatization and adaptation.

PubMed

Coles, S L; Brown, Barbara E

2003-01-01

Coral bleaching, i.e., loss of most of the symbiotic zooxanthellae normally found within coral tissue, has occurred with increasing frequency on coral reefs throughout the world in the last 20 years, mostly during periods of El Nino Southern Oscillation (ENSO). Experiments and observations indicate that coral bleaching results primarily from elevated seawater temperatures under high light conditions, which increases rates of biochemical reactions associated with zooxanthellar photosynthesis, producing toxic forms of oxygen that interfere with cellular processes. Published projections of a baseline of increasing ocean temperature resulting from global warming have suggested that annual temperature maxima within 30 years may be at levels that will cause frequent coral bleaching and widespread mortality leading to decline of corals as dominant organisms on reefs. However, these projections have not considered the high variability in bleaching response that occurs among corals both within and among species. There is information that corals and their symbionts may be capable of acclimatization and selective adaptation to elevated temperatures that have already resulted in bleaching resistant coral populations, both locally and regionally, in various areas of the world. There are possible mechanisms that might provide resistance and protection to increased temperature and light. These include inducible heat shock proteins that act in refolding denatured cellular and structural proteins, production of oxidative enzymes that inactivate harmful oxygen radicals, fluorescent coral pigments that both reflect and dissipate light energy, and phenotypic adaptations of zooxanthellae and adaptive shifts in their populations at higher temperatures. Such mechanisms, when considered in conjunction with experimental and observational evidence for coral recovery in areas that have undergone coral bleaching, suggest an as yet undefined capacity in corals and zooxanthellae to adapt to conditions that have induced coral bleaching. Clearly, there are limits to acclimatory processes that can counter coral bleaching resulting from elevated sea temperatures, but scientific models will not accurately predict the fate of reef corals until we have a better understanding of coral-algal acclimatization/adaptation potential. Research is particularly needed with respect to the molecular and physiological mechanisms that promote thermal tolerance in corals and zooxanthellae and identification of genetic characteristics responsible for the variety of responses that occur in a coral bleaching event. Only then will we have some idea of the nature of likely responses, the timescales involved and the role of 'experience' in modifying bleaching impact.

Physics-based Morphology Analysis and Adjoint Optimization of Flexible Flapping Wings

DTIC Science & Technology

2016-08-30

understand the underlying physics of flexible wings in flying insects and birds towards the bio -inspired wing designs with superior aerodynamic...flapping flights have been developed to understand the underlying physics of flexible wings in flying insects and birds towards the bio -inspired wing...been developed to understand the underlying physics of flexible wings in flying insects and birds towards the bio -inspired wing designs with superior

78 FR 66990 - Additional Designations, Foreign Narcotics Kingpin Designation Act

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-07

...) [SDNTK] (Linked To: ARRENDADORA TURIN, S.A.; Linked To: DESARROLLOS BIO GAS, S.A. DE C.V.; Linked To: ECA...] (Linked To: BLUE POINT SALT, S.A. DE C.V.; Linked To: DESARROLLOS BIO GAS, S.A. DE C.V.; Linked To: ECA ENERGETICOS, S.A. DE C.V.; Linked To: ORGANIC SALT, S.A. DE C.V.; Linked To: PETRO BIO, S. DE R.L. DE C.V...

A Green, Guided-Inquiry Based Electrophilic Aromatic Substitution for the Organic Chemistry Laboratory

ERIC Educational Resources Information Center

Eby, Eric; Deal, S. Todd

2008-01-01

We developed an alternative electrophilic aromatic substitution reaction for the organic chemistry teaching laboratory. The experiment is an electrophilic iodination reaction of salicylamide, a popular analgesic, using environmentally friendly reagents--sodium iodide and household bleach. Further, we designed the lab as a guided-inquiry…

Microleakage comparison of glass-ionomer and white mineral trioxide aggregate used as a coronal barrier in nonvital bleaching.

PubMed

Vosoughhosseini, Sepideh; Lotfi, Mehrdad; Shahmoradi, Kaveh; Saghiri, Mohammad-Ali; Zand, Vahid; Mehdipour, Masoumeh; Ranjkesh, Bahram; Mokhtari, Hadi; Salemmilani, Amin; Doosti, Sirvan

2011-11-01

There is some evidence that the pH at the root surface is reduced by intracoronal placement of bleaching pastes, which is known to enhance osteoclastic activity. Therefore, it is recommended that a protective barrier be used over the canal filling to prevent leakage of bleaching agents. Glass-ionomer (GI) is commonly used as a coronal barrier before nonvital bleaching. Because mineral trioxide aggregate (MTA) creates high alkalinity after mixing with water, using MTA as a protective barrier over the canal filling may not only prevent leakage of bleaching agents and microorganisms, but may prevent cervical resorption. The aim of this study was to evaluate sealing ability of white mineral trioxide aggregate (WMTA) as a coronal barrier before nonvital bleaching. Root canals of one hundred thirty human maxillary incisors were instrumented and filled with gutta-percha without sealer. Gutta-percha was removed up to 3 mm below the cementoenamel junction (CEJ). The teeth were randomly divided into six experimental groups of 20 teeth each and two control groups of 5. In three experimental groups, WMTA was packed into the canal to the level of CEJ. In the remaining experimental groups, glass-ionomer (GI) was used as a coronal barrier. After a 24-hour incubation period, one of the following three bleaching agents was placed in the access cavity of each of the WMTA or GI groups. These three bleaching agents were 30% hydrogen peroxide, sodium perborate mixed with 30% hydrogen peroxide, and sodium perborate mixed with distilled water. The bleaching agents were replaced every 3 days for three times. In the positive controls, no coronal barrier was used. In the negative controls, all the tooth surfaces were covered by two layers of nail varnish. Microleakage was evaluated using protein leakage test. Statistical analyses were performed with the Kruskal-Wallis and Mann-Whitney tests. The experimental groups showed minimum leakage which was not significantly more than tha in the negative controls. There was no statistically significant difference in leakage between the experimental groups (p<0.05). This study indicated that different bleaching agents have no effect on sealing ability of WMTA.

Patterns of bleaching and mortality following widespread warming events in 2014 and 2015 at the Hanauma Bay Nature Preserve, Hawai'i.

PubMed

Rodgers, Ku'ulei S; Bahr, Keisha D; Jokiel, Paul L; Richards Donà, Angela

2017-01-01

Drastic increases in global carbon emissions in the past century have led to elevated sea surface temperatures that negatively affect coral reef organisms. Worldwide coral bleaching-related mortality is increasing and data has shown even isolated and protected reefs are vulnerable to the effects of global climate change. In 2014 and 2015, coral reefs in the main Hawaiian Islands (MHI) suffered up to 90% bleaching, with higher than 50% subsequent mortality in some areas. The location and severity of bleaching and mortality was strongly influenced by the spatial and temporal patterns of elevated seawater temperatures. The main objective of this research was to understand the spatial extent of bleaching mortality in Hanauma Bay Nature Preserve (HBNP), O'ahu, Hawai'i to gain a baseline understanding of the physical processes that influence localized bleaching dynamics. Surveys at HBNP in October 2015 and January 2016 revealed extensive bleaching (47%) and high levels of coral mortality (9.8%). Bleaching was highly variable among the four HBNP sectors and ranged from a low of ∼31% in the central bay at Channel (CH) to a high of 57% in the area most frequented by visitors (Keyhole; KH). The highest levels of bleaching occurred in two sectors with different circulation patterns: KH experienced comparatively low circulation velocity and a low temperature increase while Witches Brew (WB) and Backdoors (BD) experienced higher circulation velocity and higher temperature increase. Cumulative mortality was highest at WB (5.0%) and at BD (2.9%) although WB circulation velocity is significantly higher. HBNP is minimally impacted by local factors that can lead to decline such as high fishing pressure or sedimentation although human use is high. Despite the lack of these influences, high coral mortality occurred. Visitor impacts are strikingly different in the two sectors that experienced the highest mortality evidenced by the differences in coral cover associated with visitor use however, coral mortality was similar. These results suggest that elevated temperature was more influential in coral bleaching and the associated mortality than high circulation or visitor use.

Patterns of bleaching and mortality following widespread warming events in 2014 and 2015 at the Hanauma Bay Nature Preserve, Hawai‘i

PubMed Central

2017-01-01

Drastic increases in global carbon emissions in the past century have led to elevated sea surface temperatures that negatively affect coral reef organisms. Worldwide coral bleaching-related mortality is increasing and data has shown even isolated and protected reefs are vulnerable to the effects of global climate change. In 2014 and 2015, coral reefs in the main Hawaiian Islands (MHI) suffered up to 90% bleaching, with higher than 50% subsequent mortality in some areas. The location and severity of bleaching and mortality was strongly influenced by the spatial and temporal patterns of elevated seawater temperatures. The main objective of this research was to understand the spatial extent of bleaching mortality in Hanauma Bay Nature Preserve (HBNP), O‘ahu, Hawai‘i to gain a baseline understanding of the physical processes that influence localized bleaching dynamics. Surveys at HBNP in October 2015 and January 2016 revealed extensive bleaching (47%) and high levels of coral mortality (9.8%). Bleaching was highly variable among the four HBNP sectors and ranged from a low of ∼31% in the central bay at Channel (CH) to a high of 57% in the area most frequented by visitors (Keyhole; KH). The highest levels of bleaching occurred in two sectors with different circulation patterns: KH experienced comparatively low circulation velocity and a low temperature increase while Witches Brew (WB) and Backdoors (BD) experienced higher circulation velocity and higher temperature increase. Cumulative mortality was highest at WB (5.0%) and at BD (2.9%) although WB circulation velocity is significantly higher. HBNP is minimally impacted by local factors that can lead to decline such as high fishing pressure or sedimentation although human use is high. Despite the lack of these influences, high coral mortality occurred. Visitor impacts are strikingly different in the two sectors that experienced the highest mortality evidenced by the differences in coral cover associated with visitor use however, coral mortality was similar. These results suggest that elevated temperature was more influential in coral bleaching and the associated mortality than high circulation or visitor use. PMID:28584703

Coral disease following massive bleaching in 2005 causes 60% decline in coral cover on reefs in the US Virgin Islands

USGS Publications Warehouse

Miller, J.; Muller, E.; Rogers, C.; Waara, R.; Atkinson, A.; Whelan, K.R.T.; Patterson, M.; Witcher, B.

2009-01-01

In the northeast Caribbean, doldrum-like conditions combined with elevated water temperatures in the summer/fall 2005 created the most severe coral bleaching event ever documented within this region. Video monitoring of 100 randomly chosen, permanent transects at five study sites in the US Virgin Islands revealed over 90% of the scleractinian coral cover showed signs of thermal stress by paling or becoming completely white. Lower water temperatures in October allowed some re-coloring of corals; however, a subsequent unprecedented regional outbreak of coral disease affected all sites. Five known diseases or syndromes were recorded; however, most lesions showed signs similar to white plague. Nineteen scleractinian species were affected by disease, with >90% of the disease-induced lesions occurring on the genus Montastraea. The disease outbreak peaked several months after the onset of bleaching at all sites but did not occur at the same time. The mean number of disease-induced lesions increased 51-fold and the mean area of disease-associated mortality increased 13-fold when compared with pre-bleaching disease levels. In the 12 months following the onset of bleaching, coral cover declined at all sites (average loss: 51.5%, range: 42.4-61.8%) reducing the five-site average from 21.4% before bleaching to 10.3% with most mortality caused by white plague disease, not bleaching. Continued losses through October 2007 reduced the average coral cover of the five sites to 8.3% (average 2-year loss: 61.1%, range: 53.0-79.3%). Mean cover by M. annularis (complex) decreased 51%, Colpophyllia natans 78% and Agaricia agaricites 87%. Isolated disease outbreaks have been documented before in the Virgin Islands, but never as widespread or devastating as the one that occurred after the 2005 Caribbean coral-bleaching event. This study provides insight into the effects of continued seawater warming and subsequent coral bleaching events in the Caribbean and highlights the need to understand links between coral bleaching and disease. ?? The Author(s) 2009.

A safety study in vitro for the effects of an in-office bleaching system on the integrity of enamel and dentine.

PubMed

Sulieman, M; Addy, M; Macdonald, E; Rees, J S

2004-09-01

The aim of this study was to investigate safety concerns with bleaching procedures by studying the effects of a high concentration hydrogen peroxide (HP) in-surgery bleaching product on enamel and dentine. Flat enamel and dentine samples embedded in epoxy resin were prepared from human third molar teeth. Erosion of enamel: groups of enamel samples were treated with 35% HP then citric acid (CA) or brushing with toothpaste or CA alone and water alone. Enamel Loss was measured using a profilometer. Abrasion/erosion of dentine: groups of dentine specimens were treated as follows: Group 1--brushed with water for 30 min. Group 2--brushed with 35% HP for 30 min. Group 3--power bleached for 30 min and then Group 4--brushed with toothpaste for 1 minute. Group 5--water soaked for 30 min followed by brushing with toothpaste for 1 min. Group 6--orange juice soaked for 30 min followed by brushing with toothpaste for 1 min. Treatment effects were measured using a profilometer. Hardness tests: enamel and dentine specimens were hardness tested using a Wallace indenter prior to and post bleaching. Scanning Electron Microscopy: enamel and dentine specimens were taped and the exposed tissue treated with 35% HP and then studied under scanning electronmicroscopy (SEM). Enamel erosion: bleaching enamel samples had no measurable effect on enamel. Pre-bleaching had no significant effect on subsequent CA erosion or brushing. Abrasion/erosion of dentine: no significant differences were found between treatments 1-5 with little change from baseline detected. Orange juice (Group 6) produced considerable and significantly more erosion than other treatments. Hardness tests: there were no significant changes in hardness values for enamel and dentine. SEM: there was no evidence of any topographical changes to either enamel or dentine. Using one of the highest concentrations of HP for tooth bleaching procedures and maximum likely peroxide exposure, there was no evidence of deleterious effects on enamel or dentine. It must be assumed that studies which reported adverse effects on enamel and or dentine of bleaches reflect not the bleach itself but the pH of the formulation used.

Scanning Laser Ophthalmoscope Measurement of Local Fundus Reflectance and Autofluorescence Changes Arising from Rhodopsin Bleaching and Regeneration

PubMed Central

Morgan, Jessica I. W.; Pugh, Edward N.

2013-01-01

Purpose. We measured the bleaching and regeneration kinetics of rhodopsin in the living human eye with two-wavelength, wide-field scanning laser ophthalmoscopy (SLO), and investigated the effect of rhodopsin bleaching on autofluorescence intensity. Methods. The retina was imaged with an Optos P200C SLO by its reflectance of 532 and 633 nm light, and its autofluorescence excited by 532 nm light, before and after exposure to lights calibrated to bleach rhodopsin substantially. Bleaching was confined to circular retinal regions of 4.8° visual angle located approximately 16° superotemporal and superonasal to fixation. Images were captured as 12-bit tiff files and postprocessed to extract changes in reflectance and autofluorescence. Results. At the locus of bleaching transient increases in reflectance of the 532 nm, but not the 633 nm beam were observed readily and quantified. A transient increase in autofluorescence also occurred. The action spectrum, absolute sensitivity, and recovery of the 532 nm reflectance increase were consistent with previous measurements of human rhodopsin's spectral sensitivity, photosensitivity, and regeneration kinetics. The autofluorescence changes closely tracked the changes in rhodopsin density. Conclusions. The bleaching and regeneration kinetics of rhodopsin can be measured locally in the human retina with a widely available SLO. The increased autofluorescence excited by 532 nm light upon bleaching appears primarily due to transient elimination of rhodopsin's screening of autofluorescent fluorochromes in the RPE. The spatially localized measurement with a widely available SLO of rhodopsin, the most abundant protein in the retina, could be a valuable adjunct to retinal health assessment. PMID:23412087

Scanning laser ophthalmoscope measurement of local fundus reflectance and autofluorescence changes arising from rhodopsin bleaching and regeneration.

PubMed

Morgan, Jessica I W; Pugh, Edward N

2013-03-01

We measured the bleaching and regeneration kinetics of rhodopsin in the living human eye with two-wavelength, wide-field scanning laser ophthalmoscopy (SLO), and investigated the effect of rhodopsin bleaching on autofluorescence intensity. The retina was imaged with an Optos P200C SLO by its reflectance of 532 and 633 nm light, and its autofluorescence excited by 532 nm light, before and after exposure to lights calibrated to bleach rhodopsin substantially. Bleaching was confined to circular retinal regions of 4.8° visual angle located approximately 16° superotemporal and superonasal to fixation. Images were captured as 12-bit tiff files and postprocessed to extract changes in reflectance and autofluorescence. At the locus of bleaching transient increases in reflectance of the 532 nm, but not the 633 nm beam were observed readily and quantified. A transient increase in autofluorescence also occurred. The action spectrum, absolute sensitivity, and recovery of the 532 nm reflectance increase were consistent with previous measurements of human rhodopsin's spectral sensitivity, photosensitivity, and regeneration kinetics. The autofluorescence changes closely tracked the changes in rhodopsin density. The bleaching and regeneration kinetics of rhodopsin can be measured locally in the human retina with a widely available SLO. The increased autofluorescence excited by 532 nm light upon bleaching appears primarily due to transient elimination of rhodopsin's screening of autofluorescent fluorochromes in the RPE. The spatially localized measurement with a widely available SLO of rhodopsin, the most abundant protein in the retina, could be a valuable adjunct to retinal health assessment.

Effects of modeled tropical sea surface temperature variability on coral reef bleaching predictions

NASA Astrophysics Data System (ADS)

van Hooidonk, R.; Huber, M.

2012-03-01

Future widespread coral bleaching and subsequent mortality has been projected using sea surface temperature (SST) data derived from global, coupled ocean-atmosphere general circulation models (GCMs). While these models possess fidelity in reproducing many aspects of climate, they vary in their ability to correctly capture such parameters as the tropical ocean seasonal cycle and El Niño Southern Oscillation (ENSO) variability. Such weaknesses most likely reduce the accuracy of predicting coral bleaching, but little attention has been paid to the important issue of understanding potential errors and biases, the interaction of these biases with trends, and their propagation in predictions. To analyze the relative importance of various types of model errors and biases in predicting coral bleaching, various intra- and inter-annual frequency bands of observed SSTs were replaced with those frequencies from 24 GCMs 20th century simulations included in the Intergovernmental Panel on Climate Change (IPCC) 4th assessment report. Subsequent thermal stress was calculated and predictions of bleaching were made. These predictions were compared with observations of coral bleaching in the period 1982-2007 to calculate accuracy using an objective measure of forecast quality, the Peirce skill score (PSS). Major findings are that: (1) predictions are most sensitive to the seasonal cycle and inter-annual variability in the ENSO 24-60 months frequency band and (2) because models tend to understate the seasonal cycle at reef locations, they systematically underestimate future bleaching. The methodology we describe can be used to improve the accuracy of bleaching predictions by characterizing the errors and uncertainties involved in the predictions.

Preventive Use of a Resin-based Desensitizer Containing Glutaraldehyde on Tooth Sensitivity Caused by In-office Bleaching: A Randomized, Single-blind Clinical Trial.

PubMed

Diniz, Acs; Lima, Snl; Tavarez, RRdJ; Borges, A H; Pinto, Scs; Tonetto, M R; Loguercio, A D; Bandéca, M C

2018-03-23

To evaluate the risk and intensity of bleaching-induced tooth sensitivity (TS) after in-office bleaching following topical application of a resin-based glutaraldehyde desensitizer. Thirty-three patients were randomly assigned to the experimental (Gluma Desensitizer Liquid, Heraeus Kulzer, Hanau, Germany) and placebo groups. The placebo or Gluma Desensitizer Liquid was applied for one minute prior to application of an in-office bleaching gel. Bleaching was performed with 35% hydrogen peroxide gel (three applications × 15 minutes each) over two sessions, one week apart. The color of the anterior teeth was evaluated before and 21 days after treatment using the VITA Classical shade guide, Bleachedguide 3D, and Easyshade spectrophotometer. TS during and after the bleaching was recorded according to the visual analog (VAS) and numerical rating (NRS) scales. All data were submitted to statistical analysis (α=0.05). There was no significant difference in absolute risk or intensity of TS between the two groups (risk and VAS, p=0.93 and 0.31, respectively; NRS, p≥0.45). At the end of the bleaching protocol, tooth whitening was observed in both groups, as evident from color change in shade guide units (ΔSGU, 4.1-7.1; both guides) and overall color change (ΔE, 7.4-9.3 units); however, there were no significant differences in whitening between the two groups ( p>0.11). Gluma Desensitizer Liquid was not able to reduce the risk or intensity of TS. Bleaching efficacy was not affected by application of the desensitizer.

The effects of fractional CO2 laser, Nano-hydroxyapatite and MI paste on mechanical properties of bovine enamel after bleaching

PubMed Central

Moosavi, Horieh

2017-01-01

Background This study investigated the effect of post bleaching treatments to the change of enamel elastic modulus and microhardness after dental bleaching in- vitro. Material and Methods Fifty bovine incisor slab were randomly assigned into five groups (n=10). The samples were bleached for three times; 20 minutes each time, by 40% hydrogen peroxide. Next it was applied fractional CO2 laser for two minutes, Nano- hydroxy apatite (N-HA) and MI-paste for 7 days and 2 minutes per day. The sound enamel and bleached teeth without post treatment remained as control groups. The elastic modulus and microhardness were measured at three times; 24 hours, 1 and 2 months. Data were statistically analyzed by two-way analysis of variance with 95% confidence level. Results Different methods of enamel treatment caused a significant increase in elastic modulus compared to bleached group (P<0.05). Modulus was significantly increased in 1 and 2 months (P<0/001: bleach, P= 0/015: laser, P= 0/008: NHA, P=0/010: MI paste) but there were no significantly difference between 1 and 2 months (P>0.05). There was any significance difference for hardness among treated and control groups, but hardness increased significantly by increasing storage time (P<0.05). Conclusions The use of the protective tested agents can be useful in clinical practice to reduce negative changes of enamel surface after whitening procedures. Key words:Bleaching enamel, CO2 laser, MI pastes, Nano-hydroxy apatite, Microhardness, Elastic modulus. PMID:29410753

Effect of different intracoronal bleaching methods on shear bond strength of ceramic brackets bonded to bleached enamel: An in-vitro study.

PubMed

Chauhan, Vikas; Kumar, Piush; Sharma, Payal; Shetty, Divya

2017-01-01

To investigate the effect of different intracoronal bleaching methods on the shear bond strength and site of failure of ceramic brackets. Sixty freshly extracted human maxillary incisors were randomly divided into four groups ( n = 15). Endodontic access cavity was prepared and root canals were filled, root fillings were removed 2mm apical to the cementoenamel junction, and a 2-mmthick layer of glass ionomer cement base was applied. Group 1 served as the control. Intracoronal bleaching was performed with 35% carbamide peroxide in group 2, sodium perborate in group 3, and 37.5% hydrogen peroxide in group 4. The teeth were immersed in artificial saliva for 4 weeks before bracket bonding. Ceramic brackets were bonded with composite resin and cured with LED light. After bonding, the shear bond strength of the brackets was tested with a universal testing machine. The site of bond failure was determined by modified ARI (Adhesive Remnant Index). The highest value of shear bond strength was measured in control group (18.67 ± 1.59 MPa), which was statistically significant from groups 2,3, and 4. There was no significant difference between groups 2 and 4. The lowest shear bond strength was measured in group 3. ARI scores were not significant from each other. Intracoronal bleaching significantly affected the shear bond strength of ceramic brackets even after 4 weeks of bleaching. Bleaching with sodium perborate affects shear bond strength more adversely than does bleaching with other agents like hydrogen peroxide and carbamide peroxide.

Outbreak and persistence of opportunistic symbiotic dinoflagellates during the 2005 Caribbean mass coral ‘bleaching’ event

PubMed Central

LaJeunesse, Todd C.; Smith, Robin T.; Finney, Jennifer; Oxenford, Hazel

2009-01-01

Reef corals are sentinels for the adverse effects of rapid global warming on the planet's ecosystems. Warming sea surface temperatures have led to frequent episodes of bleaching and mortality among corals that depend on endosymbiotic micro-algae (Symbiodinium) for their survival. However, our understanding of the ecological and evolutionary response of corals to episodes of thermal stress remains inadequate. For the first time, we describe how the symbioses of major reef-building species in the Caribbean respond to severe thermal stress before, during and after a severe bleaching event. Evidence suggests that background populations of Symbiodinium trenchi (D1a) increased in prevalence and abundance, especially among corals that exhibited high sensitivity to stress. Contrary to previous hypotheses, which posit that a change in symbiont occurs subsequent to bleaching, S. trenchi increased in the weeks leading up to and during the bleaching episode and disproportionately dominated colonies that did not bleach. During the bleaching event, approximately 20 per cent of colonies surveyed harboured this symbiont at high densities (calculated at less than 1.0% only months before bleaching began). However, competitive displacement by homologous symbionts significantly reduced S. trenchi's prevalence and dominance among colonies after a 2-year period following the bleaching event. While the extended duration of thermal stress in 2005 provided an ecological opportunity for a rare host-generalist symbiont, it remains unclear to what extent the rise and fall of S. trenchi was of ecological benefit or whether its increased prevalence was an indicator of weakening coral health. PMID:19740874

Influence of adhesive restorations on diffusion of H2O2 released from a bleaching agent and its toxic effects on pulp cells.

PubMed

Soares, Diana Gabriela; Pastana, Júlia Vieira; de Oliveira Duque, Carla Caroline; Dias Ribeiro, Ana Paula; Basso, Fernanda Gonçalves; Hebling, Josimeri; de Souza Costa, Carlos Alberto

2014-04-01

To assess the influence of adhesive restorations on hydrogen peroxide (H2O2) diffusion through enamel and dentin and its cytotoxicity to pulp (MDPC-23) cells. Sound and resin-restored enamel/dentin disks were stored in water for 24 h or 6 months and adapted to artificial pulp chambers. Bleaching gels with 20% or 35% H2O2 were applied to the enamel surface for 45 min, and a culture medium in direct contact with the dentin surface (extract) was applied for 1 h to the MDPC-23 cells. Cell metabolism (MTT assay) and cell morphology (SEM) were assessed. The amount of H2O2 in the extracts was also quantified (peroxidase/leuco-crystal violet reaction). A significant reduction in cell metabolism was observed between the group bleached with the 35% gel and the control group (sound, nonbleached) (p < 0.05). The H2O2 diffusion was directly related to its concentration in the bleaching gel. The variables "presence of restoration" and "time of water storage" did not significantly influence H2O2 diffusion or cell metabolism for either of the bleaching gels (p > 0.05). All bleached groups presented alterations in cell morphology related to the concentration of H2O2 in the bleaching gel. The reduction in cell metabolism and the changes in cell morphology were H2O2-concentration dependent, having no relationship with the presence of either new or aged adhesive restorations on teeth subjected to bleaching therapies.

Effect of bleaching on microhardness of esthetic restorative materials.

PubMed

Malkondu, Özlem; Yurdagüven, Haktan; Say, Esra Can; Kazazoğlu, Ender; Soyman, Mübin

2011-01-01

This study evaluated the effect of a high-concentration carbamide peroxide–containing home bleaching system (Opalescence PF) and a hydrogen peroxide–containing over-the-counter bleaching system (Treswhite Supreme) on the microhardness of two nanocomposites (Filtek Supreme XT and Premise) and leucite-reinforced glass ceramic (Empress Esthetic), glass ceramic (Empress 2 layering), and feldspathic porcelain (Matchmaker MC). A total of 100 specimens, 20 of each kind of the restorative materials, 2 mm in thickness and 10 mm in diameter, were fabricated. Then the specimens were polished with SiC paper and 1 μm alumina polishing paste. After polishing, porcelain specimens were glazed in accordance with the manufacturer's instructions. Each type of restorative material was then randomly divided into two groups (n=10), and the specimens were treated with either Opalescence PF or Treswhite Supreme. The microhardness of the specimens before bleaching (baseline) and after bleaching was determined using a digital microhardness tester. Data were analyzed using the Mann-Whitney U-test and the Wilcoxon test. Opalescence PF significantly influenced the hardness of all the restorative materials. Statistically significant decreases with respect to before bleaching were found for Premise (p=0.005), Empress Esthetic (p=0.003), Empress 2 layering (p=0.005), and Matchmaker-MC (p=0.003), whereas a statistically significant increase was observed in Filtek Supreme XT (p=0.028). The difference in the microhardness values between before and after bleaching using Treswhite Supreme was statistically significant only for Premise (p=0.022). High-concentration carbamide peroxide–containing home bleaching may affect the microhardness of restorative materials.

Ultrasonic pilot-scale reactor for enzymatic bleaching of cotton fabrics.

PubMed

Gonçalves, Idalina; Herrero-Yniesta, Victor; Perales Arce, Iratxe; Escrigas Castañeda, Monica; Cavaco-Paulo, Artur; Silva, Carla

2014-07-01

The potential of ultrasound-assisted technology has been demonstrated by several laboratory scale studies. However, their successful industrial scaling-up is still a challenge due to the limited pilot and commercial sonochemical reactors. In this work, a pilot reactor for laccase-hydrogen peroxide cotton bleaching assisted by ultrasound was scaled-up. For this purpose, an existing dyeing machine was transformed and adapted by including piezoelectric ultrasonic devices. Laboratory experiments demonstrated that both low frequency, high power (22 kHz, 2100 W) and high frequency, low power ultrasounds (850 kHz, 400 W) were required to achieve satisfactory results. Standard half (4 g/L H2O2 at 90 °C for 60 min) and optical (8 g/L H2O2 at 103 °C for 40 min) cotton bleaching processes were used as references. Two sequential stages were established for cotton bleaching: (1) laccase pretreatment assisted by high frequency ultrasound (850 kHz, 400 W) and (2) bleaching using high power ultrasound (22 kHz, 2100 W). When compared with conventional methods, combined laccase-hydrogen peroxide cotton bleaching with ultrasound energy improved the whitening effectiveness. Subsequently, less energy (temperature) and chemicals (hydrogen peroxide) were needed for cotton bleaching thus resulting in costs reduction. This technology allowed the combination of enzyme and hydrogen peroxide treatment in a continuous process. The developed pilot-scale reactor offers an enhancement of the cotton bleaching process with lower environmental impact as well as a better performance of further finishing operations. Copyright © 2014 Elsevier B.V. All rights reserved.

Investigating Motivations for Women's Skin Bleaching in Tanzania

ERIC Educational Resources Information Center

Lewis, Kelly M.; Robkin, Navit; Gaska, Karie; Njoki, Lillian Carol

2011-01-01

Why do many African women continue to use damaging skin-bleaching cosmetics that contain dangerous chemicals (e.g., mercury) that may increase their rates of infertility, skin cancer, and serious skin/brain/kidney disease? To address this question, our study investigated motivations driving the preservation of skin-bleaching practices in Tanzania.…

INDICATORS OF UV EXPOSURE IN CORAL AND THEIR RELEVANCE TO GLOBAL CLIMATE CHANGE AND CORAL BLEACHING

EPA Science Inventory

A compelling aspect of the deterioration of coral reefs is the phenomenon of coral bleaching. Bleaching can destroy large areas of a reef with limited recovery or recruitment, and it may be induced by a variety of stressors ranging from exposure to temperature and salinity extrem...

40 CFR 430.27 - Pretreatment standards for new sources (PSNS).

Code of Federal Regulations, 2010 CFR

2010-07-01

...) EFFLUENT GUIDELINES AND STANDARDS THE PULP, PAPER, AND PAPERBOARD POINT SOURCE CATEGORY Bleached Papergrade... a report submitted under 40 CFR 403.12 that it uses exclusively TCF bleaching processes at that... report submitted under 40 CFR 403.12(b), (d), or (e) that it uses exclusively TCF bleaching processes at...

FT–Raman investigation of bleaching of spruce thermomechanical pulp

Treesearch

U.P. Agarwal; L.L. Landucci

2004-01-01

Spruce thermomechanical pulp was bleached initially by alkaline hydrogen peroxide and then by sodium dithionite and sodium borohydride. Near-infrared Fourier-transform–Raman spectroscopy revealed that spectral differences were due primarily to coniferaldehyde and p-quinone structures in lignin, new direct evidence that bleaching removes p-quinone structures. In...

INDICATORS OF UV EXPOSURE IN CORALS AND THEIR RELEVANCE TO GLOBAL CLIMATE CHANGE AND CORAL BLEACHING. (R826939)

EPA Science Inventory

A compelling aspect of the deterioration of coral reefs is the phenomenon of coral bleaching. Through interactions with other factors such as sedimentation, pollution, and bacterial infection, bleaching can impact large areas of a reef with limited recovery, and it might be in...

16 CFR 260.9 - Free-of claims.

Code of Federal Regulations, 2014 CFR

2014-01-01

... intentionally to the product. Example 1: A package of t-shirts is labeled “Shirts made with a chlorine-free bleaching process.” The shirts, however, are bleached with a process that releases a reduced, but still... substantiated claim, however, that the shirts were “bleached with a process that releases 50% less of the...

16 CFR 260.9 - Free-of claims.

Code of Federal Regulations, 2013 CFR

2013-01-01

... intentionally to the product. Example 1: A package of t-shirts is labeled “Shirts made with a chlorine-free bleaching process.” The shirts, however, are bleached with a process that releases a reduced, but still... substantiated claim, however, that the shirts were “bleached with a process that releases 50% less of the...

ENSO Weather and Coral Bleaching on the Great Barrier Reef, Australia

NASA Astrophysics Data System (ADS)

McGowan, Hamish; Theobald, Alison

2017-10-01

The most devastating mass coral bleaching has occurred during El Niño events, with bleaching reported to be a direct result of increased sea surface temperatures (SSTs). However, El Niño itself does not cause SSTs to rise in all regions that experience bleaching. Nor is the upper ocean warming trend of 0.11°C per decade since 1971, attributed to global warming, sufficient alone to exceed the thermal tolerance of corals. Here we show that weather patterns during El Niño that result in reduced cloud cover, higher than average air temperatures and higher than average atmospheric pressures, play a crucial role in determining the extent and location of coral bleaching on the world's largest coral reef system, the World Heritage Great Barrier Reef (GBR), Australia. Accordingly, synoptic-scale weather patterns and local atmosphere-ocean feedbacks related to El Niño-Southern Oscillation (ENSO) and not large-scale SST warming due to El Niño alone and/or global warming are often the cause of coral bleaching on the GBR.

Diffuse reflectance study of the effects of bleaching agents in damaged dental pieces

NASA Astrophysics Data System (ADS)

Bante-Guerra, J.; Trejo-Tzab, R.; Macias, J. D.; Quintana, P.; Alvarado-Gil, J. J.

2011-03-01

One of the most important subjects of interest in dentistry and teeth preservation is related to the effects of bleaching agents on the integrity of the dental pieces. This is especially crucial when teeth surface has received some damage, generated by chemical, biological and mechanical agents or weathering in the case of dental pieces recovered from burial sites. In this work the time evolution of the effects of bleaching agents on the surface of dental pieces is monitored using diffuse reflectance in the visible spectrum is reported. The effects were monitored in teeth previously subject to chemical agents. Bleaching was induced using commercial whitening products. It is shown that the time evolution of the reflectance depends strongly on the condition of the surface as well as on the thickness of enamel. Additionally the colorimetric analysis of the samples during the bleaching is presented. This is especially useful in for comparing with previous studies. In order to complement our studies, the effects of the bleaching on the surface of the teeth were monitored by scanning electron microscopy.

Physical-chemical characteristics of whitening toothpaste and evaluation of its effects on enamel roughness.

PubMed

Hilgenberg, Sérgio Paulo; Pinto, Shelon Cristina Souza; Farago, Paulo Vitor; Santos, Fábio André; Wambier, Denise Stadler

2011-01-01

This in vitro study evaluated the physical-chemical characteristics of whitening toothpastes and their effect on bovine enamel after application of a bleaching agent (16% carbamide peroxide). Physical-chemical analysis was made considering mass loss by desiccation, ash content and pH of the toothpastes. Thirty bovine dental enamel fragments were prepared for roughness measurements. The samples were subjected to bleaching treatments and simulated brushing: G1. Sorriso Dentes Brancos (Conventional toothpaste), G2. Close-UP Whitening (Whitening toothpaste), and G3. Sensodyne Branqueador (Whitening toothpaste). The average roughness (Ra) was evaluated prior to the bleaching treatment and after brushing. The results revealed differences in the physical-chemical characteristics of the toothpastes (p < 0.0001). The final Ra had higher values (p < 0.05) following the procedures. The mean of the Ra did not show significant differences, considering toothpaste groups and bleaching treatment. Interaction (toothpaste and bleaching treatment) showed significant difference (p < 0.0001). The whitening toothpastes showed differences in their physical-chemical properties. All toothpastes promoted changes to the enamel surface, probably by the use of a bleaching agent.

A randomized controlled trial of household-based flocculant-disinfectant drinking water treatment for diarrhea prevention in rural Guatemala.

PubMed

Reller, Megan E; Mendoza, Carlos E; Lopez, M Beatriz; Alvarez, Maricruz; Hoekstra, Robert M; Olson, Christy A; Baier, Kathleen G; Keswick, Bruce H; Luby, Stephen P

2003-10-01

We conducted a study to determine if use of a new flocculant-disinfectant home water treatment reduced diarrhea. We randomly assigned 492 rural Guatemalan households to five different water treatment groups: flocculant-disinfectant, flocculant-disinfectant plus a customized vessel, bleach, bleach plus a vessel, and control. During one year of observation, residents of control households had 4.31 episodes of diarrhea per 100 person-weeks, whereas the incidence of diarrhea was 24% lower among residents of households receiving flocculant-disinfectant, 29% lower among those receiving flocculant-disinfectant plus vessel, 25% lower among those receiving bleach, and 12% lower among households receiving bleach plus vessel. In unannounced evaluations of home drinking water, free chlorine was detected in samples from 27% of flocculant-disinfectant households, 35% of flocculant-disinfectant plus vessel households, 35% of bleach households, and 43% of bleach plus vessel households. In a setting where diarrhea was a leading cause of death, intermittent use of home water treatment with flocculant-disinfectant decreased the incidence of diarrhea.

"The fairer the better?" Use of potentially toxic skin bleaching products.

PubMed

Darj, Elisabeth; Infanti, Jennifer J; Ahlberg, Beth Maina; Okumu, Jecinta

2015-12-01

Skin bleaching is a widespread phenomenon in spite of their potentially toxic health effects. This study aimed to determine if such products are used in Sweden in particular by pregnant women, furthermore to explore immigrant women's view skin bleaching. 455 pregnant women completed a questionnaire, which were statistically analysed. Focus groups and individual interviews were conducted with immigrant women, content analysis was used to assess the data. Skin bleaching products were used by 2.6% of pregnant women, significantlly more by women born in non-European countries. Motivating factors were associated with the concept of beauty together with social and economic advantages. The women had low awareness of the potential health risks of the products. Regulations on the trade of skin bleaching products have not effectively reduced the availability of the products in Sweden nor the popularity of skin bleaching. There is need for further research especially among pregnant women and possible effects on newborns. Products should be tested for toxicity. Public health information should be developed and health care providers educated and aware of this practice, due to their potential negative health implications.

Effects of cold light bleaching on the color stability of composite resins

PubMed Central

Cao, Liqun; Huang, Lijuan; Wu, Meisheng; Wei, Hua; Zhao, Shouliang

2015-01-01

To evaluate the effects of cold light bleaching on the color stability of four restorations using a thermocycling stain challenge. 160 specimens (10 mm in diameter and 2 mm thick) were fabricated from 4 composite resins (Gradia Direct-A, Z350XT, Premisa, and Précis) and divided into 4 subgroups. Color was assessed according to the CIEL*a*b* color scale at baseline, after the first cycle of bleaching, after thermocycling stain challenges, and after the second cycle of bleaching. Mean values were compared using three-way analysis of variance, and multiple comparisons of the mean values were performed using the Tukey-Kramer test. All groups showed significant color changes after stain challenge, the color change was more significant in Gradia Direct and Z350XT than in Premisa and Précis. After the second cycle of bleaching, color mostly recovered to its original values. The color stability of Gradia Direct and Z350XT was inferior to that of Premisa and Précis. The discoloration of composite resin materials can be partly removed after cold light bleaching. PMID:26309549

Dissimilar effect of perming and bleaching treatments on cuticles: advanced hair damage model based on elution and oxidation of S100A3 protein.

PubMed

Kizawa, Kenji; Inoue, Takafumi; Yamaguchi, Masahito; Kleinert, Peter; Troxler, Heinz; Heizmann, Claus W; Iwamoto, Yoshimichi

2005-01-01

Hair treatment chemicals induce sudden and severe hair damage. In this study, we examined cuticles from untreated, permed, and bleached hair that were mechanically discriminated by shaking in water. Both perming and bleaching treatments are prone to easily delaminate cuticles. Confocal microscopy revealed that the cuticles of permed hair were delaminated with larger pieces than untreated ones. On the other hand, the cuticles of bleached hair tend to fragment into small peptides. At the minimum concentration of thioglycolate required to elute S100A3 protein from the endocuticle into the reductive permanent waving lotion, enlarged delaminated cuticle fragments were observed. Although S100A3 is retained in bleached hair, S100A3 is irreversibly oxidized upon bleaching treatment. It is likely that the oxidative cleavage of disulfide bonds between cuticle-constituting proteins, including S100A3, results in the fragile property of cuticles. Here we present a more comprehensive model of hair damage based on a diverse mechanism of cuticle delamination.

Variability in bleach kinetics and amount of photopigment between individual foveal cones.

PubMed

Bedggood, Phillip; Metha, Andrew

2012-06-20

To study the bleaching dynamics of individual foveal cone photoreceptors using an adaptive optics ophthalmoscope. After dark adaptation, cones were progressively bleached and imaged by a series of flashes of 545-nm to 570-nm light at 12 Hz. Intensity measurements were made within the foveal avascular zone (FAZ) to avoid confounding signals from the inner retinal blood supply. Over 1300 cones in this region were identified and tracked through the imaging sequences. A single subject was used who demonstrated the necessary steady fixation, wide FAZ, and resolvability of cones close to the foveal center. The mean intensity of all cones was well-described by first-order kinetics. Individual cones showed marked differences from the mean, both in rate of bleach and amount of photopigment; there was an inverse correlation between these two parameters. A subset of the cones showed large oscillations in intensity consistent with interference from light scattered within the cone outer segment. These cones also bleached more quickly, implying that rapid bleaching induces greater amounts of scatter. Neighboring cones in the fovea display high variability in their optical properties.

Bionic Manufacturing: Towards Cyborg Cells and Sentient Microbots.

PubMed

Srivastava, Sarvesh Kumar; Yadav, Vikramaditya G

2018-05-01

Bio-inspired engineering applies biological design principles towards developing engineering solutions but is not practical as a manufacturing paradigm. We advocate 'bionic manufacturing', a synergistic fusion of biotic and abiotic components, to transition away from bio-inspiration toward bio-augmentation to address current limitations in bio-inspired manufacturing. Copyright © 2017 Elsevier Ltd. All rights reserved.

Double-blind whitening Night-Guard study using ten percent carbamide peroxide.

PubMed

Ouellet, D; Los, S; Case, H; Healy, R

1992-01-01

The conservative technique of professionally dispensed and supervised, home-administered vital bleaching is now a routine treatment in the dental profession. This double-blind study evaluated the Rembrandt Lightening Gel and Whitening Toothpaste for shade change, colorimeter shade change. As well, it evaluated soft tissue health by periodontal probing, plaque index, and bleeding index. A patient questionnaire evaluated perception of whitening, perception of oral hygiene, average hours per day, and average days per week. Bleaching trays were worn over a 4-week period. The bleaching system showed definitive whitening effects as evaluated with the Vita shade guide and the colorimeter. The bleaching system had no deleterious effects on the soft tissue. The Rembrandt toothpaste alone demonstrated two-shade lightening. This vital bleaching system shows definitive whitening of the teeth in short periods of time with no adverse effects.

Raman Enhancement and Photo-Bleaching of Organic Dyes in the Presence of Chemical Vapor Deposition-Grown Graphene.

PubMed

Weng, Jiaxin; Zhao, Shichao; Li, Zhiting; Ricardo, Karen B; Zhou, Feng; Kim, Hyojeong; Liu, Haitao

2017-10-19

Fluorescent organic dyes photobleach under intense light. Graphene has been shown to improve the photo-stability of organic dyes. In this paper, we investigated the Raman spectroscopy and photo-bleaching kinetics of dyes in the absence/presence of chemical vapor deposition (CVD)-grown graphene. We show that graphene enhances the Raman signal of a wide range of dyes. The photo-bleaching of the dyes was reduced when the dyes were in contact with graphene. In contrast, monolayer hexagonal boron nitride (h-BN) was much less effective in reducing the photo-bleaching rate of the dyes. We attribute the suppression of photo-bleaching to the energy or electron transfer from dye to graphene. The results highlight the potential of CVD graphene as a substrate for protecting and enhancing Raman response of organic dyes.

Designing Uniquely Addressable Bio-orthogonal Synthetic Scaffolds for DNA and RNA Origami.

PubMed

Kozyra, Jerzy; Ceccarelli, Alessandro; Torelli, Emanuela; Lopiccolo, Annunziata; Gu, Jing-Ying; Fellermann, Harold; Stimming, Ulrich; Krasnogor, Natalio

2017-07-21

Nanotechnology and synthetic biology are rapidly converging, with DNA origami being one of the leading bridging technologies. DNA origami was shown to work well in a wide array of biotic environments. However, the large majority of extant DNA origami scaffolds utilize bacteriophages or plasmid sequences thus severely limiting its future applicability as a bio-orthogonal nanotechnology platform. In this paper we present the design of biologically inert (i.e., "bio-orthogonal") origami scaffolds. The synthetic scaffolds have the additional advantage of being uniquely addressable (unlike biologically derived ones) and hence are better optimized for high-yield folding. We demonstrate our fully synthetic scaffold design with both DNA and RNA origamis and describe a protocol to produce these bio-orthogonal and uniquely addressable origami scaffolds.

A comparison between the 2010 and 2016 El-Ninō induced coral bleaching in the Indonesian waters

NASA Astrophysics Data System (ADS)

Wouthuyzen, Sam; Abrar, M.; Lorwens, J.

2018-02-01

Severe coral bleaching events are always associated with El-Ninō phenomenon which caused a rise in ocean temperature between 1-2°C and that they potentially kill the corals worldwide. There were at least four severe coral bleaching events occurred in the Indonesian waters. This study aims to compare the coral bleaching events of the 2010 and 2016 and their impact on corals in Indonesian waters. Long-term (2002-2017) remotely sensed night time sea surface temperature (SST) data acquired from Aqua MODIS Satellite were used in the analysis. Here, we calculated the mean monthly maximum (MMM)of SST as SST in normal condition in which coral can adapt to temperature; the differences between high SST in each pixel during coral bleaching events of the 2010/2016 and MMM SST, called hot spot (HS); and how long has HS occupied a certain water body, called degree of heating weeks (DHW, °C-week) and then mapped it. Results show that the MMM SST for the Indonesian waters is 29.1°C. Both bleaching events of 2010 and 2016 started and finished in the same periods of Mar-Jun and they nearly have the same pattern, but bleaching magnitude of the 2016 was stronger than 2010 with the mean SST about 0.4°C higher in May-June. The percentage of impacted areas of strong thermal stress on corals of Alert-1 plus Alert-2 status was higher in 2016 (39.4%) compared to 2010 (31.3%). Coral bleaching events in the 2010 and 2016 spread in almost all Indonesian waters and relatively occurred in the same places but with small variation in the bleaching sites that was caused by the strength/weakness of El-Ninō and upwelling phenomenon as well as the role of Indonesian through flow (ITF).

Exposure to elevated sea-surface temperatures below the bleaching threshold impairs coral recovery and regeneration following injury.

PubMed

Bonesso, Joshua Louis; Leggat, William; Ainsworth, Tracy Danielle

2017-01-01

Elevated sea surface temperatures (SSTs) are linked to an increase in the frequency and severity of bleaching events due to temperatures exceeding corals' upper thermal limits. The temperatures at which a breakdown of the coral- Symbiodinium endosymbiosis (coral bleaching) occurs are referred to as the upper thermal limits for the coral species. This breakdown of the endosymbiosis results in a reduction of corals' nutritional uptake, growth, and tissue integrity. Periods of elevated sea surface temperature, thermal stress and coral bleaching are also linked to increased disease susceptibility and an increased frequency of storms which cause injury and physical damage to corals. Herein we aimed to determine the capacity of corals to regenerate and recover from injuries (removal of apical tips) sustained during periods of elevated sea surface temperatures which result in coral stress responses, but which do not result in coral bleaching (i.e., sub-bleaching thermal stress events). In this study, exposure of the species Acropora aspera to an elevated SST of 32 °C (2 °C below the bleaching threshold, 34 °C) was found to result in reduced fluorescence of green fluorescent protein (GFP), reduced skeletal calcification and a lack of branch regrowth at the site of injury, compared to corals maintained under ambient SST conditions (26 °C). Corals maintained under normal, ambient, sea surface temperatures expressed high GFP fluorescence at the injury site, underwent a rapid regeneration of the coral branch apical tip within 12 days of sustaining injury, and showed extensive regrowth of the coral skeleton. Taken together, our results have demonstrated that periods of sustained increased sea surface temperatures, below the corals' bleaching threshold but above long-term summertime averages, impair coral recovery from damage, regardless of the onset or occurrence of coral bleaching.

Resilience in carbonate production despite three coral bleaching events in 5 years on an inshore patch reef in the Florida Keys.

PubMed

Manzello, Derek P; Enochs, Ian C; Kolodziej, Graham; Carlton, Renée; Valentino, Lauren

2018-01-01

The persistence of coral reef frameworks requires that calcium carbonate (CaCO 3 ) production by corals and other calcifiers outpaces CaCO 3 loss via physical, chemical, and biological erosion. Coral bleaching causes declines in CaCO 3 production, but this varies with bleaching severity and the species impacted. We conducted census-based CaCO 3 budget surveys using the established ReefBudget approach at Cheeca Rocks, an inshore patch reef in the Florida Keys, annually from 2012 to 2016. This site experienced warm-water bleaching in 2011, 2014, and 2015. In 2017, we obtained cores of the dominant calcifying coral at this site, Orbicella faveolata , to understand how calcification rates were impacted by bleaching and how they affected the reef-wide CaCO 3 budget. Bleaching depressed O. faveolata growth and the decline of this one species led to an overestimation of mean (± std. error) reef-wide CaCO 3 production by + 0.68 (± 0.167) to + 1.11 (± 0.236) kg m -2  year -1 when using the static ReefBudget coral growth inputs. During non-bleaching years, the ReefBudget inputs slightly underestimated gross production by - 0.10 (± 0.022) to - 0.43 (± 0.100) kg m -2  year -1 . Carbonate production declined after the first year of back-to-back bleaching in 2014, but then increased after 2015 to values greater than the initial surveys in 2012. Cheeca Rocks is an outlier in the Caribbean and Florida Keys in terms of coral cover, carbonate production, and abundance of O. faveolata , which is threatened under the Endangered Species Act. Given the resilience of this site to repeated bleaching events, it may deserve special management attention.

Differential nitric oxide synthesis and host apoptotic events correlate with bleaching susceptibility in reef corals

NASA Astrophysics Data System (ADS)

Hawkins, T. D.; Krueger, T.; Becker, S.; Fisher, P. L.; Davy, S. K.

2014-03-01

Coral bleaching poses a threat to coral reefs worldwide. As a consequence of the temperature-induced breakdown in coral-dinoflagellate symbiosis, bleaching can have extensive effects on reef communities. However, our understanding of bleaching at a cellular level is limited, and this is particularly true regarding differential susceptibility among coral species. Recent work suggests that bleaching may represent a host innate immune-like response to symbiont dysfunction that involves synthesis of the signalling compound nitric oxide (NO) and the induction of host apoptotic-like cell death. In this study, we examined the activity of apoptosis-regulating enzymes alongside oxidised NO accumulation (a proxy for NO synthesis) in the reef corals Acropora millepora, Montipora digitata, and Pocillopora damicornis during experimental thermal stress. P. damicornis was the most sensitive species, suffering mortality (tissue sloughing) after 5 days at 33 °C but non-lethal bleaching after 9 days at 31.5 °C. A. millepora bleached at 33 °C but remained structurally intact, while M. digitata showed little evidence of bleaching. P. damicornis and A. millepora both exhibited evidence of temperature-induced NO synthesis and, after 5 days of heating, levels of oxidised NO in both species were fivefold higher than in controls maintained at 28.5 °C. These responses preceded bleaching by a number of days and may have occurred before symbiont dysfunction (measured as chlorophyll a degradation and oxidised NO accumulation). In A. millepora, apparent NO synthesis correlated with the induction of host apoptotic-like pathways, while in P. damicornis, the upregulation of apoptotic pathways occurred later. No evidence of elevated NO production or apoptosis was observed in M. digitata at 33 °C and baseline activity of apoptosis-regulating enzymes was negligible in this species. These findings provide important physiological data in the context of the responses of corals to global change and suggest that early events in the host may be important in the collapse of the coral-dinoflagellate symbiosis.

Effect of Toothpaste Application Prior to Dental Bleaching on Whitening Effectiveness and Enamel Properties.

PubMed

Vieira-Junior, W F; Lima, D A N L; Tabchoury, C P M; Ambrosano, G M B; Aguiar, F H B; Lovadino, J R

2016-01-01

The purpose of this study was to investigate the effects on the enamel properties and effectiveness of bleaching using 35% hydrogen peroxide (HP) when applying toothpastes with different active agents prior to dental bleaching. Seventy enamel blocks (4 × 4 × 2 mm) were submitted to in vitro treatment protocols in a tooth-brushing machine (n=10): with distilled water and exposure to placebo gel (negative control [NC]) or HP bleaching (positive control [PC]); and brushing with differing toothpastes prior to HP bleaching, including potassium nitrate toothpaste (PN) containing NaF, conventional sodium monofluorophosphate toothpaste (FT), arginine-based toothpastes (PA and SAN), or a toothpaste containing bioactive glass (NM). Color changes were determined using the CIE L*a*b* system (ΔE, ΔL, Δa, and Δb), and a roughness (Ra) analysis was performed before and after treatments. Surface microhardness (SMH) and cross-sectional microhardness (CSMH) were analyzed after treatment. Data were analyzed with repeated measures ANOVA for Ra, one-way ANOVA (SMH, ΔE, ΔL, Δa, and Δb), split-plot ANOVA (CSMH), and Tukey post hoc test (α<0.05). The relationship between the physical surface properties and color properties was evaluated using a multivariate Canonical correlation analysis. Color changes were statistically similar in the bleached groups. After treatments, SMH and CSMH decreased in PC. SMH increased significantly in the toothpaste groups vs the negative and positive control (NM > PA = SAN > all other groups) or decreased HP effects (CSMH). Ra increased in all bleached groups, with the exception of NM, which did not differ from the NC. The variation in the color variables (ΔL, Δa, and Δb) explained 21% of the variation in the physical surface variables (Ra and SMH). The application of toothpaste prior to dental bleaching did not interfere with the effectiveness of treatment. The bioactive glass based toothpaste protected the enamel against the deleterious effects of dental bleaching.

Evaluation of an experimental rat model for comparative studies of bleaching agents

PubMed Central

Cintra, Luciano Tavares Angelo; Benetti, Francine; Ferreira, Luciana Lousada; Rahal, Vanessa; Ervolino, Edilson; Jacinto, Rogério de Castilho; Gomes, João Eduardo; Briso, André Luiz Fraga

2016-01-01

ABSTRACT Dental materials, in general, are tested in different animal models prior to their clinical use in humans, except for bleaching agents. Objectives To evaluate an experimental rat model for comparative studies of bleaching agents by investigating the influence of different concentrations and application times of H2O2 gel in the pulp tissue during in-office bleaching of rats’ vital teeth. Material and methods The right and left maxillary molars of 50 Wistar rats were bleached with 20% and 35% H2O2 gels, respectively, for 5, 10, 15, 30, or 45 min (n=10 rats/group). Ten animals (control) were untreated. The rats were killed after 2 or 30 days, and the maxillae were examined by light microscopy. Inflammation was evaluated by histomorphometric analysis with inflammatory cell counting in the coronal and radicular thirds of the pulp. The counting of fibroblasts was also performed. Scores were attributed to the odontoblastic layer and to vascular changes. The tertiary dentin area and the pulp chamber central area were histomorphometrically measured. Data were compared by the analysis of variance and the Kruskal-Wallis test (p<0.05). Results After 2 days, the amount of inflammatory cells increased in the occlusal third of the coronal pulp until the time of 15 min for both concentrations of bleaching gels. In 30 and 45 min groups of each concentration, the number of inflammatory cells decreased along with the appearance of necrotic areas. After 30 days, a reduction in the pulp chamber central area and an enlargement of tertiary dentin area were observed without the detection of inflammation areas. Conclusion The rat model of extra coronal bleaching showed to be adequate for bleaching protocols studies, as it was possible to observe alterations in the pulp tissues and in the tooth structure caused by different concentrations and periods of application of bleaching agents. PMID:27008262

Evaluation of an experimental rat model for comparative studies of bleaching agents.

PubMed

Cintra, Luciano Tavares Angelo; Benetti, Francine; Ferreira, Luciana Lousada; Rahal, Vanessa; Ervolino, Edilson; Jacinto, Rogério de Castilho; Gomes Filho, João Eduardo; Briso, André Luiz Fraga

2016-01-01

Dental materials, in general, are tested in different animal models prior to their clinical use in humans, except for bleaching agents. To evaluate an experimental rat model for comparative studies of bleaching agents by investigating the influence of different concentrations and application times of H2O2 gel in the pulp tissue during in-office bleaching of rats' vital teeth. The right and left maxillary molars of 50 Wistar rats were bleached with 20% and 35% H2O2 gels, respectively, for 5, 10, 15, 30, or 45 min (n=10 rats/group). Ten animals (control) were untreated. The rats were killed after 2 or 30 days, and the maxillae were examined by light microscopy. Inflammation was evaluated by histomorphometric analysis with inflammatory cell counting in the coronal and radicular thirds of the pulp. The counting of fibroblasts was also performed. Scores were attributed to the odontoblastic layer and to vascular changes. The tertiary dentin area and the pulp chamber central area were histomorphometrically measured. Data were compared by the analysis of variance and the Kruskal-Wallis test (p<0.05). After 2 days, the amount of inflammatory cells increased in the occlusal third of the coronal pulp until the time of 15 min for both concentrations of bleaching gels. In 30 and 45 min groups of each concentration, the number of inflammatory cells decreased along with the appearance of necrotic areas. After 30 days, a reduction in the pulp chamber central area and an enlargement of tertiary dentin area were observed without the detection of inflammation areas. The rat model of extra coronal bleaching showed to be adequate for bleaching protocols studies, as it was possible to observe alterations in the pulp tissues and in the tooth structure caused by different concentrations and periods of application of bleaching agents.

Thermal refugia against coral bleaching throughout the northern Red Sea.

PubMed

Osman, Eslam O; Smith, David J; Ziegler, Maren; Kürten, Benjamin; Conrad, Constanze; El-Haddad, Khaled M; Voolstra, Christian R; Suggett, David J

2018-02-01

Tropical reefs have been impacted by thermal anomalies caused by global warming that induced coral bleaching and mortality events globally. However, there have only been very few recordings of bleaching within the Red Sea despite covering a latitudinal range of 15° and consequently it has been considered a region that is less sensitive to thermal anomalies. We therefore examined historical patterns of sea surface temperature (SST) and associated anomalies (1982-2012) and compared warming trends with a unique compilation of corresponding coral bleaching records from throughout the region. These data indicated that the northern Red Sea has not experienced mass bleaching despite intensive Degree Heating Weeks (DHW) of >15°C-weeks. Severe bleaching was restricted to the central and southern Red Sea where DHWs have been more frequent, but far less intense (DHWs <4°C-weeks). A similar pattern was observed during the 2015-2016 El Niño event during which time corals in the northern Red Sea did not bleach despite high thermal stress (i.e. DHWs >8°C-weeks), and bleaching was restricted to the central and southern Red Sea despite the lower thermal stress (DHWs < 8°C-weeks). Heat stress assays carried out in the northern (Hurghada) and central (Thuwal) Red Sea on four key reef-building species confirmed different regional thermal susceptibility, and that central Red Sea corals are more sensitive to thermal anomalies as compared to those from the north. Together, our data demonstrate that corals in the northern Red Sea have a much higher heat tolerance than their prevailing temperature regime would suggest. In contrast, corals from the central Red Sea are close to their thermal limits, which closely match the maximum annual water temperatures. The northern Red Sea harbours reef-building corals that live well below their bleaching thresholds and thus we propose that the region represents a thermal refuge of global importance. © 2017 John Wiley & Sons Ltd.

Stress response of two coral species in the Kavaratti atoll of the Lakshadweep Archipelago, India

NASA Astrophysics Data System (ADS)

Harithsa, Shashank; Raghukumar, Chandralata; Dalal, S. G.

2005-11-01

Frequent occurrences of coral bleaching and the ensuing damage to coral reefs have generated interest in documenting stress responses that precede bleaching. The objective of this study was to assess and compare physiological changes in healthy, semi-bleached and totally bleached colonies of two coral species, Porites lutea and Acropora formosa, during a natural bleaching event in the Lakshadweep Archipelago in the Arabian Sea to determine the traits that will be useful in the diagnosis of coral health. In April 2002, three “health conditions” were observed as “appearing healthy,” “semi-bleached” and “bleached” specimens for two dominant and co-occurring coral species in these islands. Changes in the pigment composition, zooxanthellae density (ZD), mitotic index (MI) of zooxanthellae, RNA/DNA ratios and protein profile in the two coral species showing different levels of bleaching in the field were compared to address the hypothesis of no difference in health condition between species and bleaching status. The loss in chlorophyll (chl) a, chl c and ZD in the transitional stage of semi-bleaching in the branched coral A. formosa was 80, 75 and 80%, respectively. The losses were much less in the massive coral P. lutea, being 20, 50 and 25%, respectively. The decrease in zooxanthellar density and chl a was accompanied by an increased MI of zooxanthellae and RNA/DNA ratios in both the species. There was an increase in accumulation of lipofuscin granules in partially bleached P. lutea tissue, which is an indication of cellular senescence. Multivariate statistical analyses showed that colonies of P. lutea ranked in different health conditions differed significantly in chl a, chl c, ZD, RNA/DNA ratios, and protein concentrations, whereas in A. formosa chl a, chl c, chl a/ c, phaeopigments and MI contributed to the variance between health conditions.

Rheology of lyocell solutions from different cellulosic sources and development of regenerated cellulosic microfibers

NASA Astrophysics Data System (ADS)

Li, Zuopan

2003-10-01

The primary goals of the study were to develop manufactured cellulosic fibers and microfibers from wood pulps as well as from lignocellulosic agricultural by-products and to investigate alternative cellulosic sources as raw materials for lyocell solutions. A protocol was developed for the lyocell preparation from different cellulose sources. The cellulose sources included commercial dissolving pulps, commercial bleached hardwood, unbleached hardwood, bleached softwood, unbleached softwood, bleached thermomechanical pulp, unbleached thermomechanical pulp, bleached recycled newsprint, unbleached recycled newsprint, bagasse and kudzu. The rheological behavior of solutions was characterized. Complex viscosities and effective elongational viscosities were measured and the influences of parameters such as cellulose source, concentration, bleaching, and temperature were studied. One-way ANOVA post hoc tests were carried out to identify which cellulose sources have the potential to produce lyocell solutions having similar complex viscosities to those from commercial dissolving pulps. Lyocell solutions from both bleached and unbleached softwood and hardwood were classified as one homogenous subset that had the lowest complex viscosity. Kudzu solutions had the highest complex viscosity. The results showed the potential to substitute DP 1457 dissolving pulp with unbleached recycled newsprint pulps, to substitute DP 1195 dissolving pulp with bleached and unbleached thermomechanical pulps, to substitute DP 932 dissolving pulp with bleached thermomechanical pulps or bleached recycled newsprint pulps, to substitute DP 670 dissolving pulp with bagasse. Lyocell fibers were produced from selected solutions and were treated to produce microfibers. Water, sulfuric acid solutions and sodium hydroxide solutions were used. The treatment of lyocell fibers in 17.5% NaOH solutions for five minutes at 20°C successfully broke the fibers into fibrils along fiber axis. The diameters of the fibrils were generally in the range of 2 to 6 mum, and there were also finer fibrils with diameters less than 1 mum.

Coral bleaching response index: a new tool to standardize and compare susceptibility to thermal bleaching.

PubMed

Swain, Timothy D; Vega-Perkins, Jesse B; Oestreich, William K; Triebold, Conrad; DuBois, Emily; Henss, Jillian; Baird, Andrew; Siple, Margaret; Backman, Vadim; Marcelino, Luisa

2016-07-01

As coral bleaching events become more frequent and intense, our ability to predict and mitigate future events depends upon our capacity to interpret patterns within previous episodes. Responses to thermal stress vary among coral species; however the diversity of coral assemblages, environmental conditions, assessment protocols, and severity criteria applied in the global effort to document bleaching patterns creates challenges for the development of a systemic metric of taxon-specific response. Here, we describe and validate a novel framework to standardize bleaching response records and estimate their measurement uncertainties. Taxon-specific bleaching and mortality records (2036) of 374 coral taxa (during 1982-2006) at 316 sites were standardized to average percent tissue area affected and a taxon-specific bleaching response index (taxon-BRI) was calculated by averaging taxon-specific response over all sites where a taxon was present. Differential bleaching among corals was widely variable (mean taxon-BRI = 25.06 ± 18.44%, ±SE). Coral response may differ because holobionts are biologically different (intrinsic factors), they were exposed to different environmental conditions (extrinsic factors), or inconsistencies in reporting (measurement uncertainty). We found that both extrinsic and intrinsic factors have comparable influence within a given site and event (60% and 40% of bleaching response variance of all records explained, respectively). However, when responses of individual taxa are averaged across sites to obtain taxon-BRI, differential response was primarily driven by intrinsic differences among taxa (65% of taxon-BRI variance explained), not conditions across sites (6% explained), nor measurement uncertainty (29% explained). Thus, taxon-BRI is a robust metric of intrinsic susceptibility of coral taxa. Taxon-BRI provides a broadly applicable framework for standardization and error estimation for disparate historical records and collection of novel data, allowing for unprecedented accuracy in parameterization of mechanistic and predictive models and conservation plans. © 2016 John Wiley & Sons Ltd.

Coral bleaching response index: a new tool to standardize and compare susceptibility to thermal bleaching

PubMed Central

SWAIN, TIMOTHY D.; VEGA-PERKINS, JESSE B.; OESTREICH, WILLIAM K.; TRIEBOLD, CONRAD; DUBOIS, EMILY; HENSS, JILLIAN; BAIRD, ANDREW; SIPLE, MARGARET; BACKMAN, VADIM; MARCELINO, LUISA

2017-01-01

As coral bleaching events become more frequent and intense, our ability to predict and mitigate future events depends upon our capacity to interpret patterns within previous episodes. Responses to thermal stress vary among coral species; however the diversity of coral assemblages, environmental conditions, assessment protocols, and severity criteria applied in the global effort to document bleaching patterns creates challenges for the development of a systemic metric of taxon-specific response. Here, we describe and validate a novel framework to standardize bleaching response records and estimate their measurement uncertainties. Taxon-specific bleaching and mortality records (2036) of 374 coral taxa (during 1982–2006) at 316 sites were standardized to average percent tissue area affected and a taxon-specific bleaching response index (taxon-BRI) was calculated by averaging taxon-specific response over all sites where a taxon was present. Differential bleaching among corals was widely variable (mean taxon-BRI = 25.06 ± 18.44%, ± SE). Coral response may differ because holobionts are biologically different (intrinsic factors), they were exposed to different environmental conditions (extrinsic factors), or inconsistencies in reporting (measurement uncertainty). We found that both extrinsic and intrinsic factors have comparable influence within a given site and event (60% and 40% of bleaching response variance of all records explained, respectively). However, when responses of individual taxa are averaged across sites to obtain taxon-BRI, differential response was primarily driven by intrinsic differences among taxa (65% of taxon-BRI variance explained), not conditions across sites (6% explained), nor measurement uncertainty (29% explained). Thus, taxon-BRI is a robust metric of intrinsic susceptibility of coral taxa. Taxon-BRI provides a broadly applicable framework for standardization and error estimation for disparate historical records and collection of novel data, allowing for unprecedented accuracy in parameterization of mechanistic and predictive models and conservation plans. PMID:27074334

Bio-based renewable additives for anti-icing applications (phase one).

DOT National Transportation Integrated Search

2016-09-04

The performance and impacts of several bio-based anti-icers along with a traditional chloride-based anti-icer (salt brine) were evaluated. : A statistical design of experiments (uniform design) was employed for developing anti-icing liquids consistin...

The effect of fiber bleaching treatment on the properties of poly(lactic acid)/oil palm empty fruit bunch fiber composites.

PubMed

Rayung, Marwah; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Saad, Wan Zuhainis; Razak, Nur Inani Abdul; Chieng, Buong Woei

2014-08-22

In this work, biodegradable composites from poly(lactic acid) (PLA) and oil palm empty fruit bunch (OPEFB) fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of the composite. The study was extended by blending the composites with commercially available masterbatch colorant.

The Effect of Fiber Bleaching Treatment on the Properties of Poly(lactic acid)/Oil Palm Empty Fruit Bunch Fiber Composites

PubMed Central

Rayung, Marwah; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Saad, Wan Zuhainis; Razak, Nur Inani Abdul; Chieng, Buong Woei

2014-01-01

In this work, biodegradable composites from poly(lactic acid) (PLA) and oil palm empty fruit bunch (OPEFB) fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of the composite. The study was extended by blending the composites with commercially available masterbatch colorant. PMID:25153628

Life histories predict coral community disassembly under multiple stressors.

PubMed

Darling, Emily S; McClanahan, Timothy R; Côté, Isabelle M

2013-06-01

Climate change is reshaping biological communities against a background of existing human pressure. Evaluating the impacts of multiple stressors on community dynamics can be particularly challenging in species-rich ecosystems, such as coral reefs. Here, we investigate whether life-history strategies and cotolerance to different stressors can predict community responses to fishing and temperature-driven bleaching using a 20-year time series of coral assemblages in Kenya. We found that the initial life-history composition of coral taxa largely determined the impacts of bleaching and coral loss. Prior to the 1998 bleaching event, coral assemblages within no-take marine reserves were composed of three distinct life histories - competitive, stress-tolerant and weedy- and exhibited strong declines following bleaching with limited subsequent recovery. In contrast, fished reefs had lower coral cover, fewer genera and were composed of stress-tolerant and weedy corals that were less affected by bleaching over the long term. Despite these general patterns, we found limited evidence for cotolerance as coral genera and life histories were variable in their sensitivities to fishing and bleaching. Overall, fishing and bleaching have reduced coral diversity and led to altered coral communities of 'survivor' species with stress-tolerant and weedy life histories. Our findings are consistent with expectations that climate change interacting with existing human pressure will result in the loss of coral diversity and critical reef habitat. © 2013 Blackwell Publishing Ltd.

Titanium dioxide in dental enamel as a trace element and its variation with bleaching

PubMed Central

Durán-Sedó, Randall; Herrera-Sancho, Óscar-Andrey

2018-01-01

Background Titanium is a less studied trace element in dental enamel. Literature relates an increased Titanium concentration with a decreased enamel crystal domain size, which in turn is related to a higher color value. The aim of our study was to analyze the effect of tooth bleaching agents on its concentration in dental enamel by means of confocal Raman spectroscopy. Material and Methods Human teeth were randomly distributed in six experimental groups (n=10) and submitted to different bleaching protocols according to the manufacturer´s instructions. Confocal Raman spectroscopy was carried out in order to identify and quantify the presence of titanium dioxide molecules in enamel prior to and during whitening. Statistical analysis included repeated measures analysis of variance (p≤0.05) and Bonferroni pairwise comparisons. Results Titanium dioxide concentration was negatively affected by the longer bleaching protocols (at-home bleaching gels). All in-office whitening products increased significantly the studied molecule (p≤0,05). Conclusions All dental specimens depicted the presence of titanium dioxide as a trace element in dental enamel. Bleaching gels that have to be applied at higher concentrations but for shorter periods of time increase the concentration of titanium dioxide, whilst at-home whitening gels used for longer periods of time despite the lower concentration caused a loss in titanium. Key words:Bleaching, whitening, hydrogen peroxide, carbamide peroxide, Raman spectroscopy, titanium dioxide. PMID:29930771

Titanium dioxide in dental enamel as a trace element and its variation with bleaching.

PubMed

Vargas-Koudriavtsev, Tatiana; Durán-Sedó, Randall; Herrera-Sancho, Óscar-Andrey

2018-06-01

Titanium is a less studied trace element in dental enamel. Literature relates an increased Titanium concentration with a decreased enamel crystal domain size, which in turn is related to a higher color value. The aim of our study was to analyze the effect of tooth bleaching agents on its concentration in dental enamel by means of confocal Raman spectroscopy. Human teeth were randomly distributed in six experimental groups (n=10) and submitted to different bleaching protocols according to the manufacturer´s instructions. Confocal Raman spectroscopy was carried out in order to identify and quantify the presence of titanium dioxide molecules in enamel prior to and during whitening. Statistical analysis included repeated measures analysis of variance ( p ≤0.05) and Bonferroni pairwise comparisons. Titanium dioxide concentration was negatively affected by the longer bleaching protocols (at-home bleaching gels). All in-office whitening products increased significantly the studied molecule ( p ≤0,05). All dental specimens depicted the presence of titanium dioxide as a trace element in dental enamel. Bleaching gels that have to be applied at higher concentrations but for shorter periods of time increase the concentration of titanium dioxide, whilst at-home whitening gels used for longer periods of time despite the lower concentration caused a loss in titanium. Key words: Bleaching, whitening, hydrogen peroxide, carbamide peroxide, Raman spectroscopy, titanium dioxide.

In vitro Comparison of Impact of Different Bleaching Agents on the Microhardness of Enamel.

PubMed

Dey, Subhra; Pandey, Vinisha; Kumar, Anuj; Awasthi, Neha; Sahu, Anshu; Pujari, Sudarshan C

2016-03-01

Various agents are used these days for increasing the esthetics. One such procedure is bleaching that offers various advantages, as it is minimal invasive and cheap option to color the teeth and remove stain. The altered enamel after the bleaching process shows surface demineralization and porosities. The present study aimed to evaluate the effect of different bleaching agents on the microhardness of enamel. A total of 100 freshly human extracted maxillary premolar teeth were selected for the study. Teeth with sound tooth structure were included for the study. All the specimens were randomly divided into four groups with 25 specimens in each group depending upon the type of bleaching agent used: Group A, artificial saliva (Control group); Group B, 35% hydrogen peroxide (HP); Group C, 25% HP; Group D, 10% carbamide peroxide (CP). Knoop Hardness Number (KHN) was calculated at 24, 48-hour, and 7-week interval. Results showed no statistical significant differences between the microhardness of enamel of different groups (p < 0.005). A slight fall in the value of KHN was seen in all the groups, except for the control group, although the results were statistically nonsignificant (p > 0.005). Although nonsignificantly, all the bleaching solutions produced some amount of alterations in the microstructure of enamel. More studies with higher study groups and more advanced estimation technologies are required to minimize microstructure alterations and promote for better outcome of bleaching procedures.

Effect of bleaching on color stability and roughness of composite resins aged in staining beverage.

PubMed

Rodrigues, Camila Silva; Mozzaquatro, Lisandra Rossato; Dala Nora, Bárbara; Jacques, Letícia Borges; Mallmann, André

2017-01-01

Composite resin properties can be affected by contact with gel during bleaching procedures; however, there is no consensus about the effect of this contact on resin susceptibility to color change. This study aimed to evaluate staining susceptibility and surface roughness changes in 2 composite resins (Filtek Z250 XT and Filtek Z350 XT) after application of bleaching peroxides and storage in different media. Forty-two disc-shaped specimens of each composite were made, polished, and divided into 3 groups according to treatment type (35% hydrogen peroxide, 16% carbamide peroxide, or deionized water as a control group). These groups were subdivided into 2 groups according to immersion media (n = 7): deionized water or red wine. Color and average roughness (Ra) measurements were taken 24 hours after specimen preparation (T0), immediately after bleaching procedures (T1), and immediately after aging (staining; T2). Statistical analyses were performed using 2-way analyses of variance for repeated measurements and the Tukey test (P < 0.05). Bleaching resulted in minimal color change (ΔE* < 1) in all groups. Filtek Z350 XT specimens presented greater mean values of color change. The Ra values did not increase significantly after bleaching procedures or aging (staining) in all groups. Thus, bleaching agents did not significantly change the color or roughness of the composite resins used in this study.

Assessing Coral Response to a Severe Bleaching Event Using Mulimolecular Biomarkers

NASA Astrophysics Data System (ADS)

Babcock-Adams, L.; Minarro, S.; Fitt, W. K.; Medeiros, P. M.

2016-02-01

Coral bleaching events occur primarily due to increased seawater temperatures that results in the expulsion and/or reduction of endosymbiotic zooxanthellae. The Adaptive Bleaching Hypothesis suggests that bleaching events allow a different symbiont to populate the host. Specifically, the Symbiodinium clade D has been shown to increase in abundance following a bleaching event. Approximately 40 coral tissue samples (Orbicella annularis and Orbicella faveolata) were collected in the Florida Keys in March, May, August, and November of 2000, and analyzed using GC-MS for molecular biomarkers to determine if a different suite of compounds is produced at different times following the severe bleaching events in 1997 and 1998, and to relate the biomarker composition and levels to the symbiont(s) that were present in the corals. Our preliminary results show a predominant presence of saccharides (e.g., glucose, sucrose) and sterols (e.g., cholesterol, campesterol, brassicasterol), and to a lesser degree saturated (C16:0, C18:0, C20:0) and unsaturated fatty acids (C16:1; C18:1; C18:2; C20:4). The corals with the bleaching resistant clade D symbiont have higher levels of sterols as compared to corals with other non-resistant symbionts that were collected at the same time point. Concentrations of both sterols and saccharides increased throughout time, especially from March to May, which may indicate a recovery of the corals.

A comparison between boat-based and diver-based methods for quantifying coral bleaching

USGS Publications Warehouse

Zawada, David G.; Ruzicka, Rob; Colella, Michael A.

2015-01-01

Recent increases in both the frequency and severity of coral bleaching events have spurred numerous surveys to quantify the immediate impacts and monitor the subsequent community response. Most of these efforts utilize conventional diver-based methods, which are inherently time-consuming, expensive, and limited in spatial scope unless they deploy large teams of scientifically-trained divers. In this study, we evaluated the effectiveness of the Along-Track Reef Imaging System (ATRIS), an automated image-acquisition technology, for assessing a moderate bleaching event that occurred in the summer of 2011 in the Florida Keys. More than 100,000 images were collected over 2.7 km of transects spanning four patch reefs in a 3-h period. In contrast, divers completed 18, 10-m long transects at nine patch reefs over a 5-day period. Corals were assigned to one of four categories: not bleached, pale, partially bleached, and bleached. The prevalence of bleaching estimated by ATRIS was comparable to the results obtained by divers, but only for corals > 41 cm in size. The coral size-threshold computed for ATRIS in this study was constrained by prevailing environmental conditions (turbidity and sea state) and, consequently, needs to be determined on a study-by-study basis. Both ATRIS and diver-based methods have innate strengths and weaknesses that must be weighed with respect to project goals.

Removing polysaccharides-and saccharides-related coloring impurities in alkyl polyglycosides by bleaching with the H2O2/TAED/NaHCO3 system.

PubMed

Yanmei, Liu; Jinliang, Tao; Jiao, Sun; Wenyi, Chen

2014-11-04

The effect of H2O2/TAED/NaHCO3 system, namely NaHCO3 as alkaline agent with the (tetra acetyl ethylene diamine (TAED)) TAED-activated peroxide system, bleaching of alkyl polyglycosides solution was studied by spectrophotometry. The results showed that the optimal bleaching conditions about H2O2/TAED/NaHCO3 system bleaching of alkyl polyglycosides solution were as follows: molar ratio of TAED to H2O2 was 0.06, addition of H2O2 was 8.6%, addition of NaHCO3 was 3.2%, bleaching temperature of 50-65 °C, addition of MgO was 0.13%, and bleaching time was 8h. If too much amount of NaHCO3 was added to the system and maintained alkaline pH, the bleaching effect would be greatly reduced. Fixing molar ratio of TAED to H2O2 and increasing the amount of H2O2 were beneficial to improve the whiteness of alkyl polyglycosides, but adding too much amount of H2O2 would reduce the transparency. In the TAED-activated peroxide system, NaHCO3 as alkaline agent and buffer agent, could overcome the disadvantage of producing black precipitates when NaOH as alkaline agent. Copyright © 2014 Elsevier Ltd. All rights reserved.

Preemptive Use of Naproxen on Tooth Sensitivity Caused by In-Office Bleaching: A Triple-Blind, Crossover, Randomized Clinical Trial.

PubMed

Fernandes, M T; Vaez, S C; Lima, C M; Nahsan, F P; Loguércio, A D; Faria-E-Silva, A L

A triple-blind, randomized, crossover clinical trial evaluated prior use of nonsteroidal anti-inflammatory naproxen on sensitivity reported by patients undergoing in-office tooth bleaching. Fifty patients were subjected to two sessions of in-office tooth bleaching with 35% hydrogen peroxide in a single application of 40 minutes for two sessions, with an interval of seven days between applications. One hour prior to the procedure, each patient randomly received a single dose of naproxen (500 mg) or placebo. The patient's sensitivity level was evaluated during and immediately after the bleaching using two scales (verbal and visual analog); the verbal scale only was repeated after 24 hours. The effectiveness of the bleaching procedures was evaluated with the Bleachedguide scale. Relative risk to sensitivity was calculated and adjusted by session, while comparison of overall risk was performed by the McNemar test. Data on the sensitivity level for both scales and shade were subjected to the Friedman, Wilcoxon, and Mann-Whitney tests (α=0.05). The use of naproxen only decreased the absolute risk and intensity of tooth sensitivity reported immediately after the second session. On the other hand, no measurable effect was observed during or 24 hours after either session. The sequence of drug administration did not affect the bleaching effectiveness. Preemptive use of naproxen only reduced tooth sensitivity reported by patients immediately after the second session of bleaching.

Trace metal anomalies in bleached Porites coral at Meiji Reef, tropical South China Sea

NASA Astrophysics Data System (ADS)

Li, Shu; Yu, Kefu; Zhao, Jianxin; Feng, Yuexing; Chen, Tianran

2017-01-01

Coral bleaching has generally been recognized as the main reason for tropical coral reef degradation, but there are few long-term records of coral bleaching events. In this study, trace metals including chromium (Cr), copper (Cu), molybdenum (Mo), manganese (Mn), lead (Pb), tin (Sn), titanium (Ti), vanadium (V), and yttrium (Y), were analyzed in two Porites corals collected from Meiji Reef in the tropical South China Sea (SCS) to assess differences in trace metal concentrations in bleached compared with unbleached coral growth bands. Ti, V, Cr, and Mo generally showed irregular fluctuations in both corals. Bleached layers contained high concentrations of Mn, Cu, Sn, and Pb. Unbleached layers showed moderately high concentrations of Mn and Cu only. The different distribution of trace metals in Porites may be attributable to different selectivity on the basis of vital utility or toxicity. Ti, V, Cr, and Mo are discriminated against by both coral polyps and zooxanthellae, but Mn, Cu, Sn, and Pb are accumulated by zooxanthellae and only Mn and Cu are accumulated by polyps as essential elements. The marked increase in Cu, Mn, Pb, and Sn are associated with bleaching processes, including mucus secretion, tissue retraction, and zooxanthellae expulsion and occlusion. Variation in these trace elements within the coral skeleton can be used as potential tracers of short-lived bleaching events.

Biological satellite scientific devices

NASA Astrophysics Data System (ADS)

Perepech, B. L.; Rumiantsev, V. P.; Galkin, V. M.; Shakhvorostov, S. V.; Rvachev, S. S.

1991-02-01

The paper describes the NA SBS 9 systems developed for the ninth Cosmos-2044 biological test mission. The NA SBS 9 life support systems designed for monkeys and rats follow standard design of BIOS-Vivarium and BIOS-Primate units. The main features of NA SBS 9 include the use of a recently developed HF physiological data recorder Skat-3; the incorporation into BIOS-Primate of two units intended for biorhythmic studies (the BBI-Zh system for studying beetles and the VITALOG developed by NASA for studies on monkeys); and a new version of BIOS-Primate system incorporating a capacitance-link and an inductance-link temperature transmitters and a brain tissue oxygen tension control channel.

Managing calcium oxalate scale in the bleach plant

Treesearch

Alan Rudie; Peter Hart

2005-01-01

To comply with the U.S. Environmental Protection Agency's "Cluster Rule," most U.S. mills have switched from the use of chlorine to chlorine dioxide as the oxidant in the first stage of bleaching. This process change has a downside. it increases the formation of mineral scale in bleach plants. Typically, calcium oxalate forms in the chlorine dioxide...

DeviceEditor visual biological CAD canvas

PubMed Central

2012-01-01

Background Biological Computer Aided Design (bioCAD) assists the de novo design and selection of existing genetic components to achieve a desired biological activity, as part of an integrated design-build-test cycle. To meet the emerging needs of Synthetic Biology, bioCAD tools must address the increasing prevalence of combinatorial library design, design rule specification, and scar-less multi-part DNA assembly. Results We report the development and deployment of web-based bioCAD software, DeviceEditor, which provides a graphical design environment that mimics the intuitive visual whiteboard design process practiced in biological laboratories. The key innovations of DeviceEditor include visual combinatorial library design, direct integration with scar-less multi-part DNA assembly design automation, and a graphical user interface for the creation and modification of design specification rules. We demonstrate how biological designs are rendered on the DeviceEditor canvas, and we present effective visualizations of genetic component ordering and combinatorial variations within complex designs. Conclusions DeviceEditor liberates researchers from DNA base-pair manipulation, and enables users to create successful prototypes using standardized, functional, and visual abstractions. Open and documented software interfaces support further integration of DeviceEditor with other bioCAD tools and software platforms. DeviceEditor saves researcher time and institutional resources through correct-by-construction design, the automation of tedious tasks, design reuse, and the minimization of DNA assembly costs. PMID:22373390

The susceptibility and resilience of corals to thermal stress: adaptation, acclimatization or both?

PubMed

Weis, Virginia M

2010-04-01

Coral reefs are threatened with worldwide decline from multiple factors, chief among them climate change (Hughes et al. 2003; Hoegh-Guldberg et al. 2007). The foundation of coral reefs is an endosymbiosis between coral hosts and their resident photosynthetic dinoflagellates (genus Symbiodinium) and this partnership (or holobiont) is exquisitely sensitive to temperature stress. The primary response to hyperthermic stress is coral bleaching, which is the loss of symbionts from coral tissues-the collapse of the symbiosis (Weis 2008). Bleaching can result in increased coral mortality which can ultimately lead to severely compromised reef health (Hoegh-Guldberg et al. 2007). Despite this grim picture of coral bleaching and reef degradation, coral susceptibility to stress and bleaching is highly variable (Coles & Brown 2003). There is enormous interest in discovering the factors that determine susceptibility in order to help us predict if and how corals will survive a period of rapid global warming. In this issue, Barshis et al. (2010) examine the ecophysiological and genetic basis for differential responses to stress in Porites lobata in American Samoa. They combine a reciprocal transplant experimental design between two neighbouring, but very different reef environments with state-of-the-art physiological biomarkers and molecular genetic markers for both partners to tease apart the contribution of environmental and fixed influences on stress susceptibility. Their results suggest the presence of a fixed, rather than environmental effect on expression of ubiquitin conjugates, one key marker for physiological stress response. In addition, the authors show genetic differentiation in host populations between the two sites suggesting strong selection for physiological adaptation to differing environments across small geographic distances. These conclusions point the study of coral resilience and susceptibility in a new direction.

Design, Development, and Preliminary Validation for a BioContainment System for MSR

NASA Astrophysics Data System (ADS)

Fumagalli, A.; Spagnoli, B.; Terribile, A.; Indrigo, D.; Romstedt, J.; Vjendran, S.; Kminek, G.

2018-04-01

A bio-containment system was conceived, designed, and tested by Leonardo S.p.A. and partners under ESA development contract. Results achieved so far are presented, including reports of the several tests performed on development hardware.

IN VITRO STUDY OF THE PULP CHAMBER TEMPERATURE RISE DURING LIGHT-ACTIVATED BLEACHING

PubMed Central

Carrasco, Thaise Graciele; Carrasco-Guerisoli, Laise Daniela; Fröner, Izabel Cristina

2008-01-01

This study evaluated in vitro the pulp chamber temperature rise induced by the light-activated dental bleaching technique using different light sources. The root portions of 78 extracted sound human mandibular incisors were sectioned approximately 2 mm below the cementoenamel junction. The root cavities of the crowns were enlarged to facilitate the correct placing of the sensor into the pulp chamber. Half of specimens (n=39) was assigned to receive a 35% hydrogen peroxide gel on the buccal surface and the other halt (n=39) not to receive the bleaching agent. Three groups (n=13) were formed for each condition (bleach or no bleach) according to the use of 3 light sources recommended for dental bleaching: a light-emitting diode (LED)-laser system, a LED unit and a conventional halogen light. The light sources were positioned perpendicular to the buccal surface at a distance of 5 mm and activated during 30 s. The differences between the initial and the highest temperature readings for each specimen were obtained, and, from the temperature changes, the means for each specimen and each group were calculated. The values of temperature rise were compared using Kruskal-Wallis test at 1% significance level. Temperature rise varied significantly depending on the light-curing unit, with statistically significant differences (p<0.01) among the groups. When the bleaching agent was not applied, the halogen light induced the highest temperature rise (2.38±0.66°C). The LED unit produced the lowest temperature increase (0.29±0.13°C); but there was no significant difference between LED unit and LED-laser system (0.35±0.15°C) (p>0.01). When the bleaching agent was applied, there were significant differences among groups (p<0.01): halogen light induced the highest temperature rise (1.41±0.64°C), and LED-laser system the lowest (0.33±0.12°C); however, there was no difference between LED-laser system and LED unit (0.44±0.11°C). LED and LED-laser system did not differ significantly from each other regardless the temperature rise occurred with or without bleaching agent application. It may be concluded that during light-activated tooth bleaching, with or without the bleaching agent, halogen light promoted higher pulp chamber temperature rise than LED unit and LED-laser system. The tested light-curing units provided increases in the pulp chamber temperature that were compatible with pulpal health. PMID:19089234

The effect of bleaching agents on the degradation of vitamins and carotenoids in spray-dried whey protein concentrate.

PubMed

Stout, M A; Park, C W; Drake, M A

2017-10-01

Previous research has shown that bleaching affects flavor and functionality of whey proteins. The role of different bleaching agents on vitamin and carotenoid degradation is unknown. The objective of this study was to determine the effects of bleaching whey with traditional annatto (norbixin) by hydrogen peroxide (HP), benzoyl peroxide (BP), or native lactoperoxidase (LP) on vitamin and carotenoid degradation in spray-dried whey protein concentrate 80% protein (WPC80). An alternative colorant was also evaluated. Cheddar whey colored with annatto (15 mL/454 L of milk) was manufactured, pasteurized, and fat separated and then assigned to bleaching treatments of 250 mg/kg HP, 50 mg/kg BP, or 20 mg/kg HP (LP system) at 50°C for 1 h. In addition to a control (whey with norbixin, whey from cheese milk with an alternative colorant (AltC) was evaluated. The control and AltC wheys were also heated to 50°C for 1 h. Wheys were concentrated to 80% protein by ultrafiltration and spray dried. The experiment was replicated in triplicate. Samples were taken after initial milk pasteurization, initial whey formation, after fat separation, after whey pasteurization, after bleaching, and after spray drying for vitamin and carotenoid analyses. Concentrations of retinol, a-tocopherol, water-soluble vitamins, norbixin, and other carotenoids were determined by HPLC, and volatile compounds were measured by gas chromatography-mass spectrometry. Sensory attributes of the rehydrated WPC80 were documented by a trained panel. After chemical or enzymatic bleaching, WPC80 displayed 7.0 to 33.3% reductions in retinol, β-carotene, ascorbic acid, thiamin, α-carotene, and α-tocopherol. The WPC80 bleached with BP contained significantly less of these compounds than the HP- or LP-bleached WPC80. Riboflavin, pantothenic acid, pyridoxine, nicotinic acid, and cobalamin concentrations in fluid whey were not affected by bleaching. Fat-soluble vitamins were reduced in all wheys by more than 90% following curd formation and fat separation. With the exception of cobalamin and ascorbic acid, water-soluble vitamins were reduced by less than 20% throughout processing. Norbixin destruction, volatile compound, and sensory results were consistent with previous studies on bleached WPC80. The WPC80 colored with AltC had a similar sensory profile, volatile compound profile, and vitamin concentration as the control WPC80. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

A New Frontier for Cardiac Monitoring

NASA Technical Reports Server (NTRS)

2001-01-01

CardioDynamics International Corporation (CDIC) has created the BioZ(TM) System through a Small Business Innovation Research (SBIR) award from Johnson Space Center, providing patients and physicians with a cost-effective and highly accurate monitoring system.The BioZ non-invasive heart monitor is based on a technology known as Impedance Cardiography (ICG). BioZ provides the physician with vital information about the heart's ability to deliver blood to the body, the force one's heart exerts with each beat, and the amount of fluid in the chest. Specially designed bioimpedance sensors placed on the neck and chest monitor 12 different parameters, including cardiac output, contractility, systemic vascular resistance, and thoracic fluid content. These sensors monitor the electrical conductivity of the body-information that is converted into blood flow data and is displayed in real time on a monitoring screen. BioZ.com(TM) and BioZ.pc(TM) are two additional products that incorporate the same sensors present in the original BioZ system. The "com" in BioZ.com stands for cardiac output monitor. This fully integrated system is essentially a smaller version of the BioZ, combining the same abilities with a compact, lightweight design, while providing greater portability.

Effect of postoperative peroxide bleaching on the marginal seal of composite restorations bonded with self-etch adhesives.

PubMed

Roubickova, A; Dudek, M; Comba, L; Housova, D; Bradna, P

2013-01-01

The aim of this study was to determine the effect of peroxide bleaching on the marginal seal of composite restorations bonded with several adhesive systems. Combined cylindrical Class V cavities located half in enamel and half in dentin were prepared on the buccal and lingual surfaces of human molars. The cavities were bonded with the self-etch adhesives Clearfil SE-Bond (CLF), Adper Prompt (ADP), and iBond (IBO) and an etch-and-rinse adhesive Gluma Comfort Bond (GLU) and restored with a microhybrid composite Charisma. Experimental groups were treated 25 times for eight hours per day with a peroxide bleaching gel Opalescence PF 20, while the control groups were stored in distilled water for two months and then subjected to a microleakage test using a dye penetration method. Scanning electron microscopy was used to investigate the etching and penetration abilities of the adhesives and morphology of debonded restoration-enamel interfaces after the microleakage tests. Statistical analyses were performed using nonparametric Kruskal-Wallis, Mann-Whitney, and Wilcoxon tests at p=0.05. The microleakage of all GLU groups was low and not significantly affected by peroxide bleaching. Low microleakage was recorded for CLF control groups, but after bleaching, a small but significant increase in microleakage at the enamel margin indicated its sensitivity to peroxide bleaching. For ADP and IBO control groups, the microleakage at the enamel margins was significantly higher than for GLU and CLF and exceeded that at the dentin margins. Bleaching did not induce any significant changes in the microleakage. Electron microscopy analysis indicated that in our experimental setup, decreased adhesion and mechanical resistance of the ADP- and IBO-enamel interfaces could be more important than the chemical degradation effects induced by the peroxide bleaching gel.

Assessing the spatial distribution of coral bleaching using small unmanned aerial systems

NASA Astrophysics Data System (ADS)

Levy, Joshua; Hunter, Cynthia; Lukacazyk, Trent; Franklin, Erik C.

2018-06-01

Small unmanned aerial systems (sUAS) are an affordable, effective complement to existing coral reef monitoring and assessment tools. sUAS provide repeatable low-altitude, high-resolution photogrammetry to address fundamental questions of spatial ecology and community dynamics for shallow coral reef ecosystems. Here, we qualitatively describe the use of sUAS to survey the spatial characteristics of coral cover and the distribution of coral bleaching across patch reefs in Kānéohe Bay, Hawaii, and address limitations and anticipated technology advancements within the field of UAS. Overlapping sub-decimeter low-altitude aerial reef imagery collected during the 2015 coral bleaching event was used to construct high-resolution reef image mosaics of coral bleaching responses on four Kānéohe Bay patch reefs, totaling 60,000 m2. Using sUAS imagery, we determined that paled, bleached and healthy corals on all four reefs were spatially clustered. Comparative analyses of data from sUAS imagery and in situ diver surveys found as much as 14% difference in coral cover values between survey methods, depending on the size of the reef and area surveyed. When comparing the abundance of unhealthy coral (paled and bleached) between sUAS and in situ diver surveys, we found differences in cover from 1 to 49%, depending on the depth of in situ surveys, the percent of reef area covered with sUAS surveys and patchiness of the bleaching response. This study demonstrates the effective use of sUAS surveys for assessing the spatial dynamics of coral bleaching at colony-scale resolutions across entire patch reefs and evaluates the complementarity of data from both sUAS and in situ diver surveys to more accurately characterize the spatial ecology of coral communities on reef flats and slopes.

Chronic nutrient enrichment increases prevalence and severity of coral disease and bleaching.

PubMed

Vega Thurber, Rebecca L; Burkepile, Deron E; Fuchs, Corinne; Shantz, Andrew A; McMinds, Ryan; Zaneveld, Jesse R

2014-02-01

Nutrient loading is one of the strongest drivers of marine habitat degradation. Yet, the link between nutrients and disease epizootics in marine organisms is often tenuous and supported only by correlative data. Here, we present experimental evidence that chronic nutrient exposure leads to increases in both disease prevalence and severity and coral bleaching in scleractinian corals, the major habitat-forming organisms in tropical reefs. Over 3 years, from June 2009 to June 2012, we continuously exposed areas of a coral reef to elevated levels of nitrogen and phosphorus. At the termination of the enrichment, we surveyed over 1200 scleractinian corals for signs of disease or bleaching. Siderastrea siderea corals within enrichment plots had a twofold increase in both the prevalence and severity of disease compared with corals in unenriched control plots. In addition, elevated nutrient loading increased coral bleaching; Agaricia spp. of corals exposed to nutrients suffered a 3.5-fold increase in bleaching frequency relative to control corals, providing empirical support for a hypothesized link between nutrient loading and bleaching-induced coral declines. However, 1 year later, after nutrient enrichment had been terminated for 10 months, there were no differences in coral disease or coral bleaching prevalence between the previously enriched and control treatments. Given that our experimental enrichments were well within the ranges of ambient nutrient concentrations found on many degraded reefs worldwide, these data provide strong empirical support to the idea that coastal nutrient loading is one of the major factors contributing to the increasing levels of both coral disease and coral bleaching. Yet, these data also suggest that simple improvements to water quality may be an effective way to mitigate some coral disease epizootics and the corresponding loss of coral cover in the future. © 2013 John Wiley & Sons Ltd.

In vitro colorimetric evaluation of the efficacy of home bleaching and over-the-counter bleaching products.

PubMed

Dietschi, Didier; Benbachir, Nacer; Krejci, Ivo

2010-06-01

Various bleaching modalities are now offered to patients, either monitored by the dental office or self-directed, for which relative efficiency is unknown. The aim of this in vitro study was to evaluate the ability of bleaching products and protocols to lighten enamel and dentin. Bovine tooth specimens of standardized thickness (2.5 +/- 0.025 mm with similar dentin and enamel thickness) were prepared and stained with whole blood and hemolysate before being submitted to seven supervised or self-directed bleaching regimens: tray-based bleaching using 10% (Opalescence, Ultradent; Nite White, Discus Dental) or light-activated 30% (Metatray, Metatray) carbamide peroxide (CP); 6% (Zoom, Discus Dental) or 9% (TresWhite, Ultradent) hydrogen peroxide (HP); strips (Whitening Strips, Oral B-Rembrandt); and paint-on gel (Paint on Plus, Ivoclar Vivadent) containing 8.1% and 6% HP, respectively. Colorimetric measurements were performed on each specimen side, according to the CIE L*a*b* system, before and after staining, as well as after 5, 10, and the recommended number of bleaching applications. Color change after recommended number of applications (DEr) varied from 15.72 (Metatray) to 29.67 (Nite White) at enamel and 14.91 (Paint on Plus) to 41.43 (Nite White) at dentin side; Nite White (10% CP) and TresWhite (9% HP) were more effective than Metatray (30% CP) and Paint on Plus (6% HP) after 5 or the recommended number of applications. In this in vitro study based on bovine teeth, tray-based systems produced the faster and better bleaching effect, regardless of the product and concentration used, at both enamel and dentin sides.

Effect of light irradiation on tooth whitening: enamel microhardness and color change.

PubMed

Gomes, Mauricio Neves; Francci, Carlos; Medeiros, Igor Studart; De Godoy Froes Salgado, Nívea Regina; Riehl, Heraldo; Marasca, José Milton; Muench, Antônio

2009-01-01

The aim of this study was to evaluate the influence of light exposure associated with 35% hydrogen peroxide (Pola Office, SDI, Melbourne, Vic., Australia) or 15% hydrogen peroxide (BriteSmile, Discus, Culver City, CA, USA) on the microhardness and color changes of bovine enamel. Experimental groups were Britesmile + Light (BL) (15% hydrogen peroxide + plasm arc; 4 x 20 minutes), Britesmile + No Light (BN) (BL, no light), Pola office + Light (PL) (35% hydrogen peroxide + LED; 4 x 8 minutes), and Pola office + No light (PN) (PL, no light). Color changes (DeltaE) and the CIELAB (Commission Internationale de l' Eclairage, L* a* b* color system) parameters (L*, a*, and b*) were assessed with a spectrophotometer before (B), immediately (A), 1 day and 7 days after bleaching. The microhardness was measured before (B) and after (A), the obtained data were submitted to a two-way analysis of variance, and DeltaE were submitted to t-test for each period. Only Pola Office, in which the peroxide is associated with the light, improved DeltaE when evaluated immediately after bleaching (p < 0.001). Light exposure did not influence DeltaE after 1 day or 7 days for either bleaching system. The enamel microhardness was not altered after bleaching for BriteSmile. However, enamel microhardness was reduced after bleaching for Pola Office, 283 MPa (+/-21) and 265 MPa (+/-27), respectively. It was concluded that these two bleaching systems were efficient regardless of the light systems used. However, the 35% hydrogen peroxide altered the enamel microhardness. CLINICAL SIGNIFICANCE Enamel microhardness was affected by a 35% hydrogen peroxide in-office bleaching therapy. Moreover, the in-office bleaching outcome was not improved by using the light associated with systems tested in this study. (J Esthet Restor Dent 21:387-396, 2009).

Preemptive use of etodolac on tooth sensitivity after in-office bleaching: a randomized clinical trial

PubMed Central

Vaez, Savil Costa; Faria-e-Silva, André Luís; Loguércio, Alessandro Dourado; Fernandes, Micaelle Tenório Guedes; Nahsan, Flávia Pardo Salata

2018-01-01

Abstract Purpose This study determined the effectiveness of the preemptive administration of etodolac on risk and intensity of tooth sensitivity and the bleaching effect caused by in-office bleaching using 35% hydrogen peroxide. Material and methods Fifty patients were selected for this tripleblind, randomized, crossover, and placebo-controlled clinical trial. Etodolac (400 mg) or placebo was administrated in a single-dose 1 hour prior to the bleaching procedure. The whitening treatment with 35% hydrogen peroxide was carried out in two sessions with a 7-day interval. Tooth sensitivity was assessed before, during, and 24 hours after the procedure using the analog visual scale and the verbal rating scale. Color alteration was assessed by a bleach guide scale, 7 days after each session. Relative risk of sensitivity was calculated and adjusted by session, while overall risk was compared by the McNemar's test. Data on the sensitivity level of both scales and color shade were subjected to Friedman, Wilcoxon, and Mann-Whitney tests, respectively (α=0.05). Results The preemptive administration of etodolac did not affect the risk of tooth sensitivity and the level of sensitivity reported, regardless of the time of evaluation and scale used. The sequence of treatment allocation did not affect bleaching effectiveness, while the second session resulted in additional color modification. The preemptive administration of etodolac in a single dose 1 hour prior to in-office tooth bleaching did not alter tooth color, and the risk and intensity of tooth sensitivity reported by patients. Conclusion A single-dose preemptive administration of 400 mg of etodolac did not affect either risk of tooth sensitivity or level of sensitivity reported by patients, during or after the in-office tooth bleaching procedure. PMID:29412363

Preemptive use of etodolac on tooth sensitivity after in-office bleaching: a randomized clinical trial.

PubMed

Vaez, Savil Costa; Faria-E-Silva, André Luís; Loguércio, Alessandro Dourado; Fernandes, Micaelle Tenório Guedes; Nahsan, Flávia Pardo Salata

2018-02-01

This study determined the effectiveness of the preemptive administration of etodolac on risk and intensity of tooth sensitivity and the bleaching effect caused by in-office bleaching using 35% hydrogen peroxide. Fifty patients were selected for this tripleblind, randomized, crossover, and placebo-controlled clinical trial. Etodolac (400 mg) or placebo was administrated in a single-dose 1 hour prior to the bleaching procedure. The whitening treatment with 35% hydrogen peroxide was carried out in two sessions with a 7-day interval. Tooth sensitivity was assessed before, during, and 24 hours after the procedure using the analog visual scale and the verbal rating scale. Color alteration was assessed by a bleach guide scale, 7 days after each session. Relative risk of sensitivity was calculated and adjusted by session, while overall risk was compared by the McNemar's test. Data on the sensitivity level of both scales and color shade were subjected to Friedman, Wilcoxon, and Mann-Whitney tests, respectively (α=0.05). The preemptive administration of etodolac did not affect the risk of tooth sensitivity and the level of sensitivity reported, regardless of the time of evaluation and scale used. The sequence of treatment allocation did not affect bleaching effectiveness, while the second session resulted in additional color modification. The preemptive administration of etodolac in a single dose 1 hour prior to in-office tooth bleaching did not alter tooth color, and the risk and intensity of tooth sensitivity reported by patients. A single-dose preemptive administration of 400 mg of etodolac did not affect either risk of tooth sensitivity or level of sensitivity reported by patients, during or after the in-office tooth bleaching procedure.

Desire for tooth bleaching and treatment performed in Brazilian adults: findings from a birth cohort.

PubMed

Silva, Fernando Barcellos da; Chisini, Luiz Alexandre; Demarco, Flávio Fernando; Horta, Bernardo Lessa; Correa, Marcos Britto

2018-03-08

Population-based studies estimating the prevalence of tooth bleaching desire or the percentage of individuals who had performed this treatment are rare. Thus, the aim of this study was to evaluate the desire to perform tooth bleaching and the prevalence of adult individuals who had performed the treatment and investigate the association of these outcomes. A subsample (n = 536) of the 1982 Pelotas birth cohort in southern Brazil was investigated at the ages 15, 24 and 31 by clinical examinations and interviews. The prevalence of bleaching at 31 years was 15.6% [95%CI 12.6-18.9] while 85.9% [95%CI 82.7-88.7] reported they desired the treatment. Multivariate Poisson regression analysis showed that individuals who have visited the dentist within the last year showed a treatment prevalence ratio (PR) 2.31 times [95%CI 1.40-3.83] higher compared with those who had the last dental visit more than a year before the interview. Similarly, individuals with smoking habits presented an elevated PR of 1.60 [95%CI 1.00-2.55], and the low-income trajectory group showed the largest PR of desire for tooth bleaching (1.17 [95%CI 1.07-1.28]). Moreover, individuals from the high-risk caries trajectory group presented a higher prevalence of desire for tooth bleaching than individuals from low caries trajectory group. Individuals who have declared being "dissatisfied" with their dental color presented a prevalence of desire for tooth bleaching 16% greater than "satisfied" ones. Thus, the present findings confirm that tooth bleaching has become a frequently desired dental treatment to improve dental aesthetics in the population and a considerable rate of adults has performed the treatment.

Effectiveness of and Dental Sensitivity to At-home Bleaching With 4% and 10% Hydrogen Peroxide: A Randomized, Triple-blind Clinical Trial.

PubMed

Chemin, K; Rezende, M; Loguercio, A D; Reis, A; Kossatz, S

To evaluate the risk for and intensity of tooth sensitivity and color change of at-home dental bleaching with 4% and 10% hydrogen peroxide (HP). For this study, 78 patients were selected according to the inclusion and exclusion criteria and randomized into two groups: HP 4 (White Class 4%, FGM) and HP 10 (White Class 10%, FGM). In both groups, the at-home bleaching was performed for a period of 30 minutes twice a day for two weeks. The color was assessed by Vita Classical, Vita Bleachedguide 3D-MASTER and spectrophotometer Vita Easyshade (Vita Zahnfabrik) at baseline, during bleaching (first and second weeks) and after bleaching (one month). Patients recorded their tooth sensitivity using a numeric rating scale (0-4) and visual analog scale (0-10). Data from color change (DeltaE data) was submitted to two-way analysis of variance. The color change data in Delta SGU from the two shade guide units were compared with the Mann Whitney test. The risk of tooth sensitivity was evaluated by χ 2 test and the intensity of tooth sensitivity from both scales was evaluated by a Mann-Whitney test (α=0.05). The absolute risk and intensity of tooth sensitivity was higher in the group that used HP 10 than the one that used HP 4. Data from change in the number of shade guide units and color variation after one month of bleaching for both groups showed significant whitening, with no difference between groups. At-home bleaching is effective with 4% and 10% HP concentrations, but 10% HP increased the absolute risk and intensity of tooth sensitivity during at-home bleaching.

Spectrophotometric and computerized evaluation of tooth bleaching employing 10 different home-bleaching procedures: In-vitro study

PubMed Central

Peskersoy, Cem; Tetik, Ayhan; Ozturk, Veli Ozgen; Gokay, Necmi

2014-01-01

Objective: The aim of this in-vitro study was to evaluate the efficacy of bleaching products, determine the applicability and validation of the measurement methods. Materials and Methods: Freshly extracted 110 human incisor teeth were stained with whole blood and hemolysate solution prior to the application of 10 different home-bleaching products. Spectrophotometric measurements of the tooth shades were performed for each specimen before and after bleaching at the 1st, 3rd, 7th, and 14 days. Differences in lightness (Δl), chroma (Δc), hue (Δh) values and shade changes were measured to evaluate process. Computerized digital imaging analyses to determine the color changes were performed with Photoshop CS4 software (Adobe, San Jose, CA, USA). Statistical analyses were performed with analysis of variance, Scheffe and Tukey tests. Results: In all of the test groups regardless of the material used, a significant increase in lightness and hue, and decrease of chroma were observed, as compared to the control group. After recommended bleaching applications, Δl and Δh values respectively increased in group Zaris White and Brite (ZWB) and group Pola Night and Δc values showed significant decrease in groups ZWB and Rembrandt REM3 (P < 0.05). At the end of the procedure both spectrophotometric and digital imaging analysis showed ZWB was the most effective product among the others while Yotuel and Happy Smile were the least (P < 0.05). Conclusions: Home-bleaching systems showed slower but almost permanent bleaching effect likewise office-based methods. Both software and spectrophotometric analyses have advantages such as evaluating the results objectively and numerically, also treatment outcomes could be preserved. PMID:25512738

Color alteration, hydrogen peroxide diffusion, and cytotoxicity caused by in-office bleaching protocols.

PubMed

de Almeida, Letícia Cunha Amaral Gonzaga; Soares, Diana Gabriela; Gallinari, Marjorie Oliveira; de Souza Costa, Carlos Alberto; Dos Santos, Paulo Henrique; Briso, André Luiz Fraga

2015-04-01

This study evaluated the color alteration, cytotoxicity, and hydrogen peroxide (HP) diffusion associated with different in-office bleaching protocols. Bovine enamel/dentin disks were subjected to three bleaching sessions with 35 % HP (three 15-min applications), 35 % HP (one 45-min application), or 20 % HP (one 45-min application). The control group was not bleached. Before bleaching, the disks were adapted to artificial pulp chambers positioned in compartments containing 1 ml of acetate buffer or medium, so that the dentin remained in contact with these substances. Immediately after bleaching, the HP that diffused through the disks was stabilized by acetate buffer and was quantified (two-way repeated measures ANOVA/Fisher's protected least significant difference (PLSD) test; α = 5 %). Cells of mouse dental papilla cell-23 (MDPC-23) were incubated in this culture media for 1 h, followed by analysis of cellular metabolism (methyl tetrazolium assay) (one-way ANOVA/Tukey test; α = 5 %) and morphology (scanning electron microscopy). The specimen color alteration (ΔE) was analyzed by reflection spectrophotometry (two-way repeated measures ANOVA/Fisher's PLSD test; α = 5 %). All protocols showed equal effectiveness at the end of the treatment. HP diffusion was significantly higher in the groups bleached with 35 % HP. Reapplication of 35 % HP resulted in increased diffusion only in the first session; however, the decrease in cell metabolism was similar for all studied protocols. Despite greater peroxide diffusion in the groups treated with 35 % HP, all protocols showed the same effectiveness and were cytotoxic to MDPC-23 cells. Bleaching protocols using high HP concentrations should be avoided because they exert aggressive actions on odontoblast-like cells.

Effect of vital tooth bleaching on solubility and roughness of dental cements.

PubMed

Londono, Jimmy; Abreu, Amara; Nelson, Steve; Hernandez, Jorge; Torres, Carlos; Mettenburg, Donald; Looney, Stephen; Rueggeberg, Frederick

2009-09-01

Vital tooth bleaching may affect properties of dental cements used for fixed prostheses. The purpose of this study was to examine the effect of a combined in-office and at-home bleaching regimen on changes in surface roughness and depth loss of a variety of commercially available dental cements. Five cement classifications were tested: glass ionomer, resin-modified glass ionomer, resin,self-adhesive resin cement, and zinc phosphate. Cements were placed in multiple wells in plastic blocks. After setting,the surface profile of each block was determined, and average roughness and vertical height of cement surface from the specimen holder were recorded. Blocks were water stored (control) or subjected to in-office and at-home bleaching(n=12). Surfaces were rescanned and pre- and posttest parameter changes were calculated. Statistical analysis consisted of Mann-Whitney-Wilcoxon Rank Sum and Student t tests applied to control and bleaching parameterc hanges within the same cements. A family-wise alpha of .05 was maintained by using a Bonferroni-adjusted level of significance preset to .01 per test. Zinc phosphate showed the only significant depth increase (P=.004) from bleaching: 0.9 +/- 0.7 microm deeper than the water-control group. Only resin-modified glass ionomer showed a significant (P=.004) increase in roughness from bleaching; values increased by 0.05 +/- 0.03 microm over the water-control group. In-office and at-home bleaching significantly increased depth loss of zinc phosphate and increased resinmodified glass ionomer roughness. However, the absolute values of differences observed, as compared to the wateronly control, were considered to be clinically insignificant. (J Prosthet Dent 2009;102:148-154)

Influence of different types of light on the response of the pulp tissue in dental bleaching: a systematic review.

PubMed

Benetti, Francine; Lemos, Cleidiel Aparecido Araújo; de Oliveira Gallinari, Marjorie; Terayama, Amanda Miyuki; Briso, André Luiz Fraga; de Castilho Jacinto, Rogério; Sivieri-Araújo, Gustavo; Cintra, Luciano Tavares Angelo

2018-05-01

This systematic review (PROSPERO register: CRD42016053140) investigated the influence of different types of light on the pulp tissue during dental bleaching. Two independent authors conducted a systematic search and risk of bias evaluations. An electronic search was undertaken (PubMed/Medline, Embase, The Cochrane Library, and other databases) until May 2017. The population, intervention, comparison, outcomes (PICO) question was: "Does the light in dental bleaching change the response of the pulp to the bleaching procedure?" The intervention involved pulp tissue/cells after bleaching with light, while the comparison involved pulp tissue/cells after bleaching without light. The primary outcome was the inflammation/cytotoxicity observed in pulp after bleaching. Out of 2210 articles found, 12 articles were included in the review; four were in vivo studies (one study in dogs/others in human), and eight were in vitro studies (cell culture/with artificial pulp chamber or not). The light source used was halogen, light-emitting diode (LED), and laser. Only one in vivo study that used heat to simulate light effects showed significant pulp inflammation. Only two in vitro studies demonstrated that light influenced cell metabolism; one using halogen light indicated negative effects, and the other using laser therapy indicated positive effects. Given that animal and in vitro studies have been identified, there remain some limitations for extrapolation to the human situation. Furthermore, different light parameters were used. The effects of dental bleaching on the pulp are not influenced by different types of light, but different light parameters can influence these properties. There is insufficient evidence about the influence of different types of light on inflammation/cytotoxicity of the pulp.

Specializing on vulnerable habitat: Acropora selectivity among damselfish recruits and the risk of bleaching-induced habitat loss

NASA Astrophysics Data System (ADS)

Bonin, M. C.

2012-03-01

Coral reef habitats are increasingly being degraded and destroyed by a range of disturbances, most notably climate-induced coral bleaching. Habitat specialists, particularly those associated with susceptible coral species, are clearly among the most vulnerable to population decline or extinction. However, the degree of specialization on coral microhabitats is still unclear for one of the most ubiquitous, abundant and well studied of coral reef fish families—the damselfishes (Pomacentridae). Using high taxonomic resolution surveys of microhabitat use and availability, this study provides the first species-level description of patterns of Acropora selectivity among recruits of 10 damselfish species in order to determine their vulnerability to habitat degradation. In addition, surveys of the bleaching susceptibility of 16 branching coral species revealed which preferred recruitment microhabitats are at highest risk of decline as a result of chronic coral bleaching. Four species (i.e., Chrysiptera parasema, Pomacentrus moluccensis, Dascyllus melanurus and Chromis retrofasciata) were identified as highly vulnerable because they used only branching hard corals as recruitment habitat and primarily associated with only 2-4 coral species. The bleaching surveys revealed that five species of Acropora were highly susceptible to bleaching, with more than 50% of colonies either severely bleached or already dead. These highly susceptible corals included two of the preferred microhabitats of the specialist C. parasema and represented a significant proportion of its total recruitment microhabitat. In contrast, highly susceptible corals were rarely used by another specialist, P. moluccensis, suggesting that this species faces a lower risk of bleaching-induced habitat loss compared to C. parasema. As degradation to coral reef habitats continues, specialists will increasingly be forced to use alternative recruitment microhabitats, and this is likely to reduce population replenishment. Future research should focus on examining the fitness costs of using these alternative microhabitats.

Tooth Whitening And Temperature Rise With Two Bleaching Activation Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abu-ElMagd, D. M.; El-Sayad, I. I.; Abd El-Gawad, L. M.

2009-09-27

To measure the tooth whitening and the surface and Intrapulpal temperature increase in vitro on freshly extracted upper human central incisors after chemical, Zoom AP light and diode laser activated bleaching. Thirty caries-free upper human incisors were selected. Teeth were divided into three equal groups according to the methods of activation of the bleaching agent (n = 10). A whitening gel containing hydrogen peroxide was applied to the buccal surface of all teeth. Group I was bleached using chemically activated hydrogen peroxide gel, for three applications of 15 min each. Group II was bleached with high intensity advanced power Zoommore » activation light (Zoom AP), for three applications of 15 min each. Group III was bleached with diode laser activation technique, where the teeth were irradiated with 2 Watt diode laser for three applications of 30 sec each. The whitening degree was assessed using an image analysis system, while temperature rise was recorded using a thermocouple on the external tooth surface and Intrapulpal. The degree of whitening increased significantly in all groups. However, the percentage of whitening was not statistically significantly different between the three groups. In addition, group II showed statistically significant higher mean rise in both surface and pulp temperatures than group I and group III. Chemical bleaching produces the same whitening effect as Zoom AP light and laser, with no surface or pulpal temperature rise. Laser application is faster and produces less surface and pulp temperature increase than Zoom AP light. Diode laser used to activate bleaching gels is not considered dangerous to the vitality of dental pulp using power settings of 2 W.« less

Bleaching response of coral species in the context of assemblage response

NASA Astrophysics Data System (ADS)

Swain, Timothy D.; DuBois, Emily; Goldberg, Scott J.; Backman, Vadim; Marcelino, Luisa A.

2017-06-01

Caribbean coral reefs are declining due to a mosaic of local and global stresses, including climate change-induced thermal stress. Species and assemblage responses differ due to factors that are not easily identifiable or quantifiable. We calculated a novel species-specific metric of coral bleaching response, taxon- α and - β, which relates the response of a species to that of its assemblages for 16 species over 18 assemblages. By contextualizing species responses within the response of their assemblages, the effects of environmental factors are removed and intrinsic differences among taxa are revealed. Most corals experience either a saturation response, overly sensitive to weak stress ( α > 0) but under-responsive compared to assemblage bleaching ( β < 1), or a threshold response, insensitive to weak stress ( α < 0) but over-responsive compared to assemblage bleaching ( β > 1). This metric may help reveal key factors of bleaching susceptibility and identify species as targets for conservation.

Bleaching response of coral species in the context of assemblage response.

PubMed

Swain, Timothy D; DuBois, Emily; Goldberg, Scott J; Backman, Vadim; Marcelino, Luisa A

2017-06-01

Caribbean coral reefs are declining due to a mosaic of local and global stresses, including climate change-induced thermal stress. Species and assemblage responses differ due to factors that are not easily identifiable or quantifiable. We calculated a novel species-specific metric of coral bleaching response, taxon-α and -β, which relates the response of a species to that of its assemblages for 16 species over 18 assemblages. By contextualizing species responses within the response of their assemblages, the effects of environmental factors are removed and intrinsic differences among taxa are revealed. Most corals experience either a saturation response, overly-sensitive to weak stress (α > 0) but under-responsive compared to assemblage bleaching (β < 1), or a threshold response, insensitive to weak stress (α < 0) but over-responsive compared to assemblage bleaching (β > 1). This metric may help reveal key factors of bleaching susceptibility and identify species as targets for conservation.

Influence of Coral Community Structure and Thermal Stress Exposure on Observed Patterns of Bleaching across the Northern Mariana Islands

NASA Astrophysics Data System (ADS)

Johnston, L.; Heron, S. F.; Johnson, S.; Okano, R.; Benavente, D.; Iguel, J.; Perez, D. I.; Liu, G.; Geiger, E.; Eakin, C. M.

2016-02-01

In 2013 and 2014, the Mariana Archipelago experienced consecutive thermal stress events that resulted in widespread coral bleaching and mortality. Using in situ survey data collected across seven of the Northern Mariana Islands during the 2014 event, we undertook the first quantitative comparison between the National Oceanic and Atmospheric Administration's Coral Reef Watch 5 km satellite monitoring products and coral bleaching observations. Analysis of coral community characteristics, historical temperature conditions and thermal stress revealed a strong influence of coral biodiversity in the patterns of observed bleaching. This illustrates the importance of using local benthic characteristics to interpret the level of impact from thermal stress exposure. In an era of continuing climate change, accurate monitoring of thermal stress and prediction of coral bleaching are essential for resource managers and stakeholders to direct resources to the most effective management actions to conserve coral reefs.

Use of xylanase in the TCF bleaching of eucalyptus kraft pulp

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roncero, B.; Vidal, T.; Torres, A.L.

1996-10-01

Environmental pressures are forcing the pulp and paper industry to develop new technologies that reduce or eliminate the presence of various contaminants in bleaching plant effluents. Oxygen delignification techniques, replacement of elemental chlorine with chlorine dioxide, ozone, hydrogen peroxide and new agents as well as the use of xylanase enzymes for biobleaching, reduce o eliminate the production of chlorinated organic substances. This paper compares the sequence XOZP with OZP in the bleaching of Eucalyptus globulus kraft pulps. It has been studied the influence of enzymatic treatment on the consumption of bleaching agents: ozone and hydrogen peroxide. Chemical, physical, optical andmore » refining properties of pulps, as well as COD and colour of effluent are also studied. The xylanase treatment is positive and it is possible to manufacture fully bleached pulps at high brightness and viscosity without using chlorine compounds at a low ozone and hydrogen peroxide consumption.« less

Optical Emission Spectroscopy of an Atmospheric Pressure Plasma Jet During Tooth Bleaching Gel Treatment.

PubMed

Šantak, Vedran; Zaplotnik, Rok; Tarle, Zrinka; Milošević, Slobodan

2015-11-01

Optical emission spectroscopy was performed during atmospheric pressure plasma needle helium jet treatment of various tooth-bleaching gels. When the gel sample was inserted under the plasma plume, the intensity of all the spectral features increased approximately two times near the plasma needle tip and up to two orders of magnitude near the sample surface. The color change of the hydroxylapatite pastille treated with bleaching gels in conjunction with the atmospheric pressure plasma jet was found to be in correlation with the intensity of OH emission band (309 nm). Using argon as an additive to helium flow (2 L/min), a linear increase (up to four times) of OH intensity and, consequently, whitening (up to 10%) of the pastilles was achieved. An atmospheric pressure plasma jet activates bleaching gel, accelerates OH production, and accelerates tooth bleaching (up to six times faster).

Visual and digital comparative tooth colour assessment methods and atomic force microscopy surface roughness.

PubMed

Grundlingh, A A; Grossman, E S; Shrivastava, S; Witcomb, M J

2013-10-01

This study compared digital and visual colour tooth colour assessment methods in a sample of 99 teeth consisting of incisors, canines and pre-molars. The teeth were equally divided between Control, Ozicure Oxygen Activator bleach and Opalescence Quick bleach and subjected to three treatments. Colour readings were recorded at nine intervals by two assessment methods, VITA Easyshade and VITAPAN 3D MASTER TOOTH GUIDE, giving a total of 1782 colour readings. Descriptive and statistical analysis was undertaken using a GLM test for Analysis of Variance for a Fractional Design set at a significance of P < 0.05. Atomic force micros copy was used to examine treated ename surfaces and establish surface roughness. Visual tooth colour assessment showed significance for the independent variables of treatment, number of treatments, tooth type and the combination tooth type and treatment. Digital colour assessment indicated treatment and tooth type to be of significance in tooth colour change. Poor agreement was found between visual and digital colour assessment methods for Control and Ozicure Oxygen Activator treatments. Surface roughness values increased two-fold for Opalescence Quick specimens over the two other treatments, implying that increased light scattering improved digital colour reading. Both digital and visual colour matching methods should be used in tooth bleaching studies to complement each other and to compensate for deficiencies.

Analytic quantification of the bleaching effect of a 4-hydroxyanisole-tretinoin combination on actinic lentigines.

PubMed

Piérard-Franchimont, Claudine; Henry, Frédérique; Quatresooz, Pascale; Vroome, Valérie; Piérard, Gérald E

2008-09-01

Solar lentigines represent a common feature of photoaging, particularly on the back of the hands. Bleaching agents are usually proposed to lighten the shade of the lesions. The study was randomized and designed to assess the effect of a bleaching solution containing 2% mequinol (4-hydroxyanisole, 4HA) and 0.01% tretinoin (Solagé). The formulation was applied twice daily for 3 months on solar lentigines present on the back of one hand. The lesions on the other hand were treated with the ethyl alcohol vehicle which served as a control. Clinical diagnosis was confirmed using dermoscopy. In addition, objective measurements of the hypermelanosis were performed at 1-month intervals during and after treatment. Clinical assessments were used as well as narrow-band reflectance spectrophotometry, image analysis of video-recorded ultraviolet light-enhanced visualization (ULEV method) and photodensitometry of the corneomelametry test. The multipronged assessment of the lesional color demonstrated a significant lightening effect of the 4HA/tretinoin solution. This was demonstrated after 2 months of treatment and was maintained at least 2 months after stopping treatment. Both the visual ratings and the objective bioinstrumental methods indicate the rapid lightening effect of the 4HA/tretinoin formulation. After stopping treatment, the rate of repigmentation appeared to have slowed compared to the depigmentation phase.

The escape problem for mortal walkers

NASA Astrophysics Data System (ADS)

Grebenkov, D. S.; Rupprecht, J.-F.

2017-02-01

We introduce and investigate the escape problem for random walkers that may eventually die, decay, bleach, or lose activity during their diffusion towards an escape or reactive region on the boundary of a confining domain. In the case of a first-order kinetics (i.e., exponentially distributed lifetimes), we study the effect of the associated death rate onto the survival probability, the exit probability, and the mean first passage time. We derive the upper and lower bounds and some approximations for these quantities. We reveal three asymptotic regimes of small, intermediate, and large death rates. General estimates and asymptotics are compared to several explicit solutions for simple domains and to numerical simulations. These results allow one to account for stochastic photobleaching of fluorescent tracers in bio-imaging, degradation of mRNA molecules in genetic translation mechanisms, or high mortality rates of spermatozoa in the fertilization process. Our findings provide a mathematical ground for optimizing storage containers and materials to reduce the risk of leakage of dangerous chemicals or nuclear wastes.

Peptide structure: Its effect on penetration into human hair.

PubMed

Silva, Carla J S M; Vasconcelos, Andreia; Cavaco-Paulo, Artur

2007-01-01

The influence of the peptide structure on its penetration inside hair was studied, together with the effect of hair bleaching (oxidation). For that reason, the outcome of positioning a charged sequence (KAKAK) either at the N or C terminal on hair penetration has been studied for peptides with 17 residues each. It was observed that the penetration of these peptides into hair was driven by electrostatic interactions, where the position of the charged group at the peptide structure was of major importance. The penetration was only achieved for damaged hair due to its higher negative charge at the membrane surface. It was also observed that the peptides were able to restore the original tensile strength of bleached hair. Consequently, the knowledge of hair surface properties is of extreme importance when designing peptides directed for hair treatment.

The design of financial recording system in industrial bio-briquette of Ramie (Boehmeria nivea) decortication waste with design thinking approach

NASA Astrophysics Data System (ADS)

Irianto, R.; Purnomo, D.; Prima, S.; Wulandari, A.

2017-05-01

The production process of ramie (boehmeria nivea) fibers generates waste which contents 5.95 to 7.83% ash; 1.88 to 2.87% silicate; 30.67 to 31.08% lignin; 33.81 to 35.99% alpha cellulose; 62.95 to 63.78% holoselulosa; 17.43 to 18.14% pentosan, which can be used as raw material of bio-briquette. Those potential can be used to generate a business opportunity, such as industrial bio-briquette of ramie decortication waste. The purpose of this research is to create accounting information which could present an income statement that is easily applied on industrial bio-briquette of ramie decortication waste. This research use descriptive analysis method with design with design thinking approach to gather the information through depth observation on human being as the object to achieve the purpose. The result in this research is financial recording system of industrial bio-briquette of ramie decortication waste in a desktop application. The system is integrated with production activities according to the needs of accounting information particularly at managerial production. The existing applications creates information in the form of financial operations which can be used as a factor in decision-making.

Electrochemical mercerization, souring, and bleaching of textiles

DOEpatents

Cooper, J.F.

1995-10-10

Economical, pollution-free treatment of textiles occurs in a low voltage electrochemical cell that mercerizes (or scours), sours, and optionally bleaches without effluents and without the purchase of bulk caustic, neutralizing acids, or bleaches. The cell produces base in the cathodic chamber for mercerization and an equivalent amount of acid in the anodic chamber for neutralizing the fabric. Gas diffusion electrodes are used for one or both electrodes and may simultaneously generate hydrogen peroxide for bleaching. The preferred configuration is a stack of bipolar electrodes, in which one or both of the anode and cathode are gas diffusion electrodes, and where no hydrogen gas is evolved at the cathode. 5 figs.

Electrochemical mercerization, souring, and bleaching of textiles

DOEpatents

Cooper, John F.

1995-01-01

Economical, pollution-free treatment of textiles occurs in a low voltage electrochemical cell that mercerizes (or scours), sours, and optionally bleaches without effluents and without the purchase of bulk caustic, neutralizing acids, or bleaches. The cell produces base in the cathodic chamber for mercerization and an equivalent amount of acid in the anodic chamber for neutralizing the fabric. Gas diffusion electrodes are used for one or both electrodes and may simultaneously generate hydrogen peroxide for bleaching. The preferred configuration is a stack of bipolar electrodes, in which one or both of the anode and cathode are gas diffusion electrodes, and where no hydrogen gas is evolved at the cathode.

Water quality and coral bleaching thresholds: formalising the linkage for the inshore reefs of the Great Barrier Reef, Australia.

PubMed

Wooldridge, Scott A

2009-05-01

The threats of wide-scale coral bleaching and reef demise associated with anthropogenic climate change are widely known. Here, the additional role of poor water quality in lowering the thermal tolerance (i.e. bleaching 'resistance') of symbiotic reef corals is considered. In particular, a quantitative linkage is established between terrestrially-sourced dissolved inorganic nitrogen (DIN) loading and the upper thermal bleaching thresholds of inshore reefs on the Great Barrier Reef, Australia. Significantly, this biophysical linkage provides concrete evidence for the oft-expressed belief that improved coral reef management will increase the regional-scale survival prospects of corals reefs to global climate change. Indeed, for inshore reef areas with a high runoff exposure risk, it is shown that the potential benefit of this 'local' management imperative is equivalent to approximately 2.0-2.5 degrees C in relation to the upper thermal bleaching limit; though in this case, a potentially cost-prohibitive reduction in end-of-river DIN of >50-80% would be required. An integrated socio-economic modelling framework is outlined that will assist future efforts to understand (optimise) the alternate tradeoffs that the water quality/coral bleaching linkage presents.

Ultrastructural evaluation of enamel after dental bleaching associated with fluoride.

PubMed

Dominguez, John A; Bittencourt, Bruna; Michel, Milton; Sabino, Nilson; Gomes, João Carlos; Gomes, Osnara M M

2012-08-01

This study evaluated the effects on human enamel after two bleaching procedures: with a fluoridated bleaching agent and with topical fluoride application postbleaching. It used 43 enamel blocks (3 mm(2) ) that were ground flat (600-2,000 grit) and polished with polishing paste (one and one-fourth). Specimens were randomly divided into three groups according to the bleaching procedure: (1) control group, (2) hydrogen peroxide 35% (HPF) and topical application of fluoride 1.23%, and (3) HP 38% (OP) with fluoride in its composition. Bleaching agents were used according to the manufacturer's instructions. Three methodologies were used: nanoindentation, to observe surface hardness and elastic modulus; atomic force microscopy, to observe surface roughness (R(a) - R(z)); and scanning electron microscopy, to observe the enamel surface effects. Group OP had a decrease in the elastic modulus after bleaching, which was recovered at 14 days. An increased roughness (R(a); 32%) was observed on group HPF and had an increased erosion on enamel surface (67%). It was concluded that topical application of fluoride, after using the nonfluoridated whitening agent, increased the roughness values and erosion of enamel. Copyright © 2012 Wiley Periodicals, Inc.

ESR investigation of ROS generated by H2O2 bleaching with TiO2 coated HAp.

PubMed

Saita, Makiko; Kobayashi, Kyo; Kobatashi, Kyou; Yoshino, Fumihiko; Hase, Hiriko; Nonami, Toru; Kimoto, Katsuhiko; Lee, Masaichi-Chang-il

2012-01-01

It is well known that clinical bleaching can be achieved with a solution of 30% hydrogen peroxide (H2O2) or H2O2/titanium dioxide (TiO2) combination. This study examined the hypothesis that TiO2 coated with hydroxyapatite (HAp-TiO2) can generate reactive oxygen species (ROS). ROS are generated via photocatalysis using electron spin resonance (ESR). The bleaching properties of HAp-TiO2 in the presence of H2O2 can be measured using hematoporphyrin litmus paper and extracted teeth. We demonstrate that superoxides (O2(•-)) and hydroxyl radicals (HO(•)) can be generated through excitation of anatase TiO2, rutile TiO2, anatase HAp-TiO2, and rutile HAp-TiO2 in the presence of H2O2. The combination of R HAp-TiO2 with H2O2 produced the highest level of HO(•) generation and the most marked bleaching effects of all the samples. The superior bleaching effects exhibited by R HAp-TiO2 with H2O2 suggest that this combination may lead to novel methods for the clinical application of bleaching treatments.

A Chemical Approach to Mitigate Coral Bleaching

NASA Astrophysics Data System (ADS)

Marty-Rivera, M.; Yudowski, G.

2016-02-01

Changes in sea surface temperature and irradiance can induce bleaching and increase mortality in corals. Coral bleaching occurs when symbiotic algae living inside the coral is degraded or expelled, reducing the availability of energetic resources. Oxidative stress has been suggested as a possible molecular mechanism triggering bleaching. We hypothesized that reduction of reactive oxygen species (ROS) during stress could mitigate or prevent coral bleaching. We utilized the coral Porites Astreoides as our model to test the effects of two natural antioxidants, catechin and Resveratrol, on thermally induced bleaching. Coral fragments were exposed to four treatments: high temperature (32°C), high temperature plus antioxidants (1μM), ambient temperature (25°C), or ambient temperature (25°C) plus antioxidant for four days. A total of 8 corals were used per treatment. We measured several photobiological parameters, such as maximum quantum yield and light curves to assess the viability of symbiodinium spp. after thermal stress in the presence of antioxidants. Preliminary experiments on a model species, the sea anemone Aiptasia pallida and corals, showed that exposure to antioxidants reduced intracellular levels of ROS. Additionally, antioxidant-treated anemones showed higher photosynthetic efficiency (67%) than those exposed to high-temperature alone.

Determination of nicotine content in teeth submitted to prophylaxis and in-office bleaching by gas chromatography-mass spectrometry (GC-MS).

PubMed

de Geus, Juliana L; Beltrame, Flávio L; Wang, Mei; Avula, Bharathi; Khan, Ikhlas A; Loguercio, Alessandro D; Kossatz, Stella; Reis, Alessandra

2018-02-21

The objective of this study was to evaluate the dental color exposed to acute cigarette smoke treatment and quantify the amount of nicotine in samples exposed to cigarette smoke, after dental prophylaxis and after in-office bleaching. Sixty-nine healthy human molars were subjected to cigarette smoke in a cigarette machine. The teeth were divided into three groups: positive control, prophylaxis, and bleaching. Forty cycles of smoke exposition with duration of 15 min each were performed using 10 cigarettes (positive control). Dental prophylaxis was performed with a rotating brush and prophylaxis paste; in-office bleaching was performed with 35% hydrogen peroxide, in two sessions of three 15-min applications, with a 1-week interval between sessions. The color was evaluated at the baseline, after exposure to cigarette smoke, after dental prophylaxis, and after in-office bleaching. Teeth from each group were powdered and analyzed by gas chromatography-mass spectrometry in order to measure the amount of nicotine present in each group. Data from quantification of nicotine and color change were analyzed by one-way ANOVA and Tukey's test (α = 0.05). Data for subjective and objective color evaluation, a perceptible dental darkening occurred in teeth after exposure to cigarette smoke. Dental prophylaxis was able to recover the original color of teeth however, only after bleaching teeth became whiter than at the baseline (p < 0.001). The amount of nicotine was significantly different and higher in positive control group (3.3 ± 1.3 μg/g of tooth), followed by the prophylaxis group (2.1 ± 1.4 μg/g) and the bleaching group (0.8 ± 0.3 μg/g) (p < 0.001). Cigarette smoke penetrates into the dental structure. Dental prophylaxis and bleaching with 35% hydrogen peroxide can partially remove the nicotine from tobacco smoke. However, when in-office bleaching was applied, a more significant nicotine removal was achieved. Dental prophylaxis could remove most of the external nicotine-staining on the tooth surfaces while bleaching could further reduce the external and internal nicotine-staining of teeth.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, J; Park, S; Lee, H

Purpose: This work evaluated the characteristics of optically stimulated luminescence dosimeters (OSLDs) with fully filled deep electron/hole traps (OSLDfull) with the bleaching conditions according to the accumulated dose. Methods: The OSLDs were first pre-irradiated with a Co-60 gamma ray at more than 5 kGy, so as to fill the deep electron and hole traps. Using a 6-MV beam, the OSLDfull characteristics were investigated in terms of the full bleaching, fading, dose linearity, and dose sensitivity obtained in response to the accumulated dose values. To facilitate a comparison of the dose sensitivity, OSLDs with un-filled deep electron/hole traps (OSLDempty) were investigatedmore » in the same manner. A long-pass filter was used to exclude bleaching-source wavelengths of less than 520 nm. Various bleaching time and wavelength combinations were used in order to determine the optimal bleaching conditions for the OSLD full. Results: The fading for the OSLDfull exhibited stable signals after 8 min, for both 1- and 10-Gy. For 4-h bleaching time and an unfiltered bleaching device, the supralinear index values for the OSLDfull were 1.003, 1.002, 0.999, and 1.001 for doses of 2, 4, 7, and 10 Gy, respectively. For a 65-Gy accumulated dose with a 5-Gy fraction, no variation in dose sensitivity was obtained for the OSLDfull, within a standard deviation of 0.85%, whereas the OSLDempty dose sensitivity decreased by approximately 2.3% per 10 Gy. The filtered bleaching device yielded a highly stable sensitivity for OSLDfull, independent of bleaching time and within a standard deviation of 0.71%, whereas the OSLDempty dose sensitivity decreased by approximately 4.2% per 10 Gy for an accumulated dose of 25 Gy with a 5-Gy fraction. Conclusion: Under the bleaching conditions determined in this study, clinical dosimetry with OSLDfull is highly stable, having an accuracy of 1% with no change in dose sensitivity or linearity at clinical doses. This work was supported by a National Research Foundation of Korea (NRF) grant, funded by the Korea government (MISP) (No. 2014M2B2A4031164), and by the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (HI14C3459).« less

Climate change and coral reef bleaching: An ecological assessment of long-term impacts, recovery trends and future outlook

NASA Astrophysics Data System (ADS)

Baker, Andrew C.; Glynn, Peter W.; Riegl, Bernhard

2008-12-01

Since the early 1980s, episodes of coral reef bleaching and mortality, due primarily to climate-induced ocean warming, have occurred almost annually in one or more of the world's tropical or subtropical seas. Bleaching is episodic, with the most severe events typically accompanying coupled ocean-atmosphere phenomena, such as the El Niño-Southern Oscillation (ENSO), which result in sustained regional elevations of ocean temperature. Using this extended dataset (25+ years), we review the short- and long-term ecological impacts of coral bleaching on reef ecosystems, and quantitatively synthesize recovery data worldwide. Bleaching episodes have resulted in catastrophic loss of coral cover in some locations, and have changed coral community structure in many others, with a potentially critical influence on the maintenance of biodiversity in the marine tropics. Bleaching has also set the stage for other declines in reef health, such as increases in coral diseases, the breakdown of reef framework by bioeroders, and the loss of critical habitat for associated reef fishes and other biota. Secondary ecological effects, such as the concentration of predators on remnant surviving coral populations, have also accelerated the pace of decline in some areas. Although bleaching severity and recovery have been variable across all spatial scales, some reefs have experienced relatively rapid recovery from severe bleaching impacts. There has been a significant overall recovery of coral cover in the Indian Ocean, where many reefs were devastated by a single large bleaching event in 1998. In contrast, coral cover on western Atlantic reefs has generally continued to decline in response to multiple smaller bleaching events and a diverse set of chronic secondary stressors. No clear trends are apparent in the eastern Pacific, the central-southern-western Pacific or the Arabian Gulf, where some reefs are recovering and others are not. The majority of survivors and new recruits on regenerating and recovering coral reefs have originated from broadcast spawning taxa with a potential for asexual growth, relatively long distance dispersal, successful settlement, rapid growth and a capacity for framework construction. Whether or not affected reefs can continue to function as before will depend on: (1) how much coral cover is lost, and which species are locally extirpated; (2) the ability of remnant and recovering coral communities to adapt or acclimatize to higher temperatures and other climatic factors such as reductions in aragonite saturation state; (3) the changing balance between reef accumulation and bioerosion; and (4) our ability to maintain ecosystem resilience by restoring healthy levels of herbivory, macroalgal cover, and coral recruitment. Bleaching disturbances are likely to become a chronic stress in many reef areas in the coming decades, and coral communities, if they cannot recover quickly enough, are likely to be reduced to their most hardy or adaptable constituents. Some degraded reefs may already be approaching this ecological asymptote, although to date there have not been any global extinctions of individual coral species as a result of bleaching events. Since human populations inhabiting tropical coastal areas derive great value from coral reefs, the degradation of these ecosystems as a result of coral bleaching and its associated impacts is of considerable societal, as well as biological concern. Coral reef conservation strategies now recognize climate change as a principal threat, and are engaged in efforts to allocate conservation activity according to geographic-, taxonomic-, and habitat-specific priorities to maximize coral reef survival. Efforts to forecast and monitor bleaching, involving both remote sensed observations and coupled ocean-atmosphere climate models, are also underway. In addition to these efforts, attempts to minimize and mitigate bleaching impacts on reefs are immediately required. If significant reductions in greenhouse gas emissions can be achieved within the next two to three decades, maximizing coral survivorship during this time may be critical to ensuring healthy reefs can recover in the long term.

SynBioSS-aided design of synthetic biological constructs.

PubMed

Kaznessis, Yiannis N

2011-01-01

We present walkthrough examples of using SynBioSS to design, model, and simulate synthetic gene regulatory networks. SynBioSS stands for Synthetic Biology Software Suite, a platform that is publicly available with Open Licenses at www.synbioss.org. An important aim of computational synthetic biology is the development of a mathematical modeling formalism that is applicable to a wide variety of simple synthetic biological constructs. SynBioSS-based modeling of biomolecular ensembles that interact away from the thermodynamic limit and not necessarily at steady state affords for a theoretical framework that is generally applicable to known synthetic biological systems, such as bistable switches, AND gates, and oscillators. Here, we discuss how SynBioSS creates links between DNA sequences and targeted dynamic phenotypes of these simple systems. Copyright © 2011 Elsevier Inc. All rights reserved.

Creating a Bio-Inspired Solution to Prevent Erosion

NASA Astrophysics Data System (ADS)

Reher, R.; Martinez, A.; Cola, J.; Frost, D.

2016-12-01

Through the study of geophysical sciences, lessons can be developed which allow for the introduction of bio-inspired design and art concepts to K-5 elementary students. Students are placed into an engineering mindset in which they must apply the concepts of bio-geotechnics to observe how we can use nature to prevent and abate erosion. Problems are staged for students using realistic engineering scenarios such as erosion prevention through biomimicry and the study of anchorage characteristics of root structures in regard to stability of soil. Specifically, a lesson is introduced where students research, learn, and present information about bio-inspired designs to understand these concepts. They lean how plant roots differ in size and shape to stabilize soil. In addition, students perform a series of hands-on experiments which demonstrate how bio-cements and roots can slow erosion.

Influence of bleaching agents on surface roughness of sound or eroded dental enamel specimens.

PubMed

Azrak, Birgül; Callaway, Angelika; Kurth, Petra; Willershausen, Brita

2010-12-01

The aim of the present in vitro study was to assess the effect of bleaching agents on eroded and sound enamel specimens. Enamel specimens prepared from human permanent anterior teeth were incubated with different bleaching agents containing active ingredients as 7.5 or 13.5% hydrogen peroxide or 35% carbamide peroxide, ranging in pH from 4.9 to 10.8. The effect of the tooth whitening agents on surface roughness was tested for sound enamel surfaces as well as for eroded enamel specimens. To provoke erosive damage, the enamel specimens were incubated for 10 hours with apple juice (pH = 3.4). Afterwards, pretreated and untreated dental slices were incubated with one of the bleaching agents for 10 hours. The surface roughness (R(a)) of all enamel specimens (N = 80) was measured using an optical profilometric device. A descriptive statistical analysis of the R(a) values was performed. The study demonstrated that exposure to an acidic bleaching agent (pH = 4.9) resulted in a higher surface roughness (p = 0.043) than treatment with a high peroxide concentration (pH = 6.15). If the enamel surface was previously exposed to erosive beverages, subsequent bleaching may enhance damage to the dental hard tissue. Bleaching agents with a high concentration of peroxide or an acidic pH can influence the surface roughness of sound or eroded enamel. © 2010, COPYRIGHT THE AUTHORS. JOURNAL COMPILATION © 2010, WILEY PERIODICALS, INC.

Skin Bleaching and Dermatologic Health of African and Afro-Caribbean Populations in the US: New Directions for Methodologically Rigorous, Multidisciplinary, and Culturally Sensitive Research.

PubMed

Benn, Emma K T; Alexis, Andrew; Mohamed, Nihal; Wang, Yan-Hong; Khan, Ikhlas A; Liu, Bian

2016-12-01

Skin-bleaching practices, such as using skin creams and soaps to achieve a lighter skin tone, are common throughout the world and are triggered by cosmetic reasons that oftentimes have deep historical, economic, sociocultural, and psychosocial roots. Exposure to chemicals in the bleaching products, notably, mercury (Hg), hydroquinone, and steroids, has been associated with a variety of adverse health effects, such as Hg poisoning and exogenous ochronosis. In New York City (NYC), skin care product use has been identified as an important route of Hg exposure, especially among Caribbean-born blacks and Dominicans. However, surprisingly sparse information is available on the epidemiology of the health impacts of skin-bleaching practices among these populations. We highlight the dearth of large-scale, comprehensive, community-based, clinical, and translational research in this area, especially the limited skin-bleaching-related research among non-White populations in the US. We offer five new research directions, including investigating the known and under-studied health consequences among populations for which the skin bleach practice is newly emerging at an alarming rate using innovative laboratory and statistical methods. We call for conducting methodologically rigorous, multidisciplinary, and culturally sensitive research in order to provide insights into the root and the epidemiological status of the practice and provide evidence of exposure-outcome associations, with an ultimate goal of developing potential intervention strategies to reduce the health burdens of skin-bleaching practice.