Influence of blood contamination on bond strength of a self-etching system.

OBJECTIVES: To detect the influence of blood contamination (BC) on the bond strength (BS) of a self-etching bonding system (SES) to enamel and dentine. METHODS: 25 human molars were longitudinally sectioned on the mesio-distal axis in order to obtain 50 specimens, which were embedded in acrylic resin. At first, the specimens were ground to expose a flat surface of enamel, and a bond strength test was performed. Afterwards, the samples were ground again in order to obtain a flat surface of dentine. Ten groups (total: n=100) were assigned according to substrate (enamel and dentine), step in the bonding sequence when contamination occurred (before the acidic primer and after the bonding resin), and contamination treatment (dry or rinse and dry procedure). Fresh human blood was introduced either before or after SES application (Clearfil SE Bond) and treated with air drying, or by rinsing and drying following application. Composite resin (Filtek Z-250,3M ESPE) was applied as inverted, truncated cured cones that were debonded in tension. RESULTS: The mean tensile BS values (MPa) for enamel/dentine were 19.4/23.0 and 17.1/10.0 for rinse-and-dry treatment (contamination before and after SES, respectively); while the measurements for the dry treatment, 16.2/23.3 and 0.0/0.0 contamination before and after SES, respectively. CONCLUSIONS: It was determined that blood contamination impaired adhesion to enamel and dentine when it occurred after bond light curing. Among the tested contamination treatments, the rinse-and-dry treatment produced the highest bond strength with BC after SES application, but it was not sufficient to recover the BS in the contamination-free group.

Salivary Contamination and Decontamination: Bond Strength to Dentin of Primary and Permanent Teeth

Aim: To evaluate the effects of salivary contamination and decontamination on bond strength of two one-step adhesives to primary and permanent dentin. Methods: Dentin specimens were prepared from extracted primary and permanent molars (210 of each) and were distributed to seven groups (n=15/group/molar type) for each adhesive (Xeno V+ and Scotchbond Universal): no saliva contamination (control); saliva contamination before or after light-curing of the adhesives followed either by air-drying, by rinsing with water and air-drying, or by rinsing with water, air-drying and reapplication of the adhesives. Resin composite was applied and the specimens were stored for 24h (37°C, 100% humidity). Then, shear bond strength (SBS) was measured and data analyzed with nonparametric ANOVA and Wilcoxon rank sum tests. Results: Saliva contamination reduced SBS of Xeno V+, the reduction being more pronounced when contamination occurred before light-curing than after. In both situations, decontamination involving reapplication of the adhesive restored SBS. Saliva contamination had no significant effect on Scotchbond Universal. There were no differences in SBS between primary and permanent teeth. Conclusion: Saliva contamination reduced SBS of Xeno V+, but not of Scotchbond Universal. SBS was restored when contaminated dentin was rinsed with water and air-dried followed by reapplication of the adhesive.

Effect of Salivary Contamination and Decontamination on Bond Strength of Two One-Step Self-Etching Adhesives to Dentin of Primary and Permanent Teeth

Purpose: To evaluate the effects of human saliva contamination and two decontamination procedures at different stages of the bonding procedure on the bond strength of two one-step self-etching adhesives to primary and permanent dentin. Materials and Methods: Extracted human primary and permanent molars (210 of each) were ground to mid-coronal dentin. The dentin specimens were randomly divided into 7 groups (n = 15/group/molar type) for each adhesive (Xeno V+ and Scotchbond Universal): no saliva contamination (control); saliva contamination before or after light curing of the adhesives followed by air drying, rinsing with water spray/air drying, or by rinsing with water spray/air drying/reapplication of the adhesives. Resin composite (Filtek Z250) was applied on the treated dentin surfaces. The specimens were stored at 37°C and 100% humidity for 24 h. After storage, shear bond strength (SBS) was measured and data analyzed with nonparametric ANOVA followed by exact Wilcoxon rank sum tests. Results: Xeno V+ generated significantly higher SBS than Scotchbond Universal when no saliva contamination occurred. Saliva contamination reduced SBS of Xeno V+, with the reduction being more pronounced when contamination occurred before light curing than after. In both situations, decontamination involving reapplication of the adhesive restored SBS. Saliva contamination had no significant effect on Scotchbond Universal. There were no differences in SBS between primary and permanent teeth. Conclusion: Rinsing with water and air drying followed by reapplication of the adhesive restored bond strength to saliva-contaminated dentin.

SALSA: a tool to estimate the stray light contamination for low-Earth orbit observatories

Stray light contamination reduces considerably the precision of photometric of faint stars for low altitude spaceborne observatories. When measuring faint objects, the necessity of coping with stray light contamination arises in order to avoid systematic impacts on low signal-to-noise images. Stray light contamination can be represented by a flat offset in CCD data. Mitigation techniques begin by a comprehensive study during the design phase, followed by the use of target pointing optimisation and post-processing methods. We present a code that aims at simulating the stray-light contamination in low-Earth orbit coming from reflexion of solar light by the Earth. StrAy Light SimulAtor (SALSA) is a tool intended to be used at an early stage as a tool to evaluate the effective visible region in the sky and, therefore to optimise the observation sequence. SALSA can compute Earth stray light contamination for significant periods of time allowing missionwide parameters to be optimised (e.g. impose constraints on the point source transmission function (PST) and/or on the altitude of the satellite). It can also be used to study the behaviour of the stray light at different seasons or latitudes. Given the position of the satellite with respect to the Earth and the Sun, SALSA computes the stray light at the entrance of the telescope following a geometrical technique. After characterising the illuminated region of the Earth, the portion of illuminated Earth that affects the satellite is calculated. Then, the flux of reflected solar photons is evaluated at the entrance of the telescope. Using the PST of the instrument, the final stray light contamination at the detector is calculated. The analysis tools include time series analysis of the contamination, evaluation of the sky coverage and an objects visibility predictor. Effects of the South Atlantic Anomaly and of any shutdown periods of the instrument can be added. Several designs or mission concepts can be easily tested and compared. The code is not thought as a stand-alone mission designer. Its mandatory inputs are a time series describing the trajectory of the satellite and the characteristics of the instrument. This software suite has been applied to the design and analysis of CHEOPS (CHaracterizing ExOPlanet Satellite). This mission requires very high precision photometry to detect very shallow transits of exoplanets. Different altitudes and characteristics of the detector have been studied in order to find the best parameters, that reduce the effect of contamination. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Alkylphenol Contamination in Homarus americanus

Alkylphenols are pollutants that are present in marine sediments and fishes. In earlier work it has been discovered that alkylphenols are present in the Homarus americanus, or the American lobster. Research suggests that alkylphenols could behave as endocrine disruptors as they have been found to affect juvenile hormone activity. It has been hypothesized that lobsters may be able to rid themselves of alkylphenol contamination through secreting these compounds into the environment or sequestering them in their tissues. In this study, I address the question of how lobsters may rid themselves of alkylphenols by analyzing hemolymph, muscle, gill, and shell samples and by looking for the presence of alkylphenols in natural and artificially injected lobsters. A total of thirty lobsters were analyzed. In my first study I found alkylphenols only in the gill tissue samples of natural lobsters after alkylphenols were initially found in the hemolymph, and found none in the muscle and shell samples. The types of alkylphenols found in the gills were often different than the alkylphenols found in the hemolymph. The gills are known as a site for exchange for the lobster. The lobster may not only be excreting alkylphenols from its gill surfaces but these findings suggest that the lobster may also be acquiring alkylphenols in the environment from these surfaces. It is possible that the lobsters may have ingested additional contaminants after the hemolymph samples were taken and before the gill samples were taken. As for the shell and muscle samples, it is possible that by our method the levels were too low to detect since we have a threshold of detection of 1ng/mL. It is also a conclusion that alkylphenols were not sequestered in these tissues. In the second study, an expanded set of muscles samples from natural lobsters were tested as well as additional lobsters that were artificially injected with one of our alkylphenol compounds of interest, compound three. We found that lobsters injected with peak three showed significantly higher alkylphenol concentrations in all tissues, most notably the gill samples. The non-injected lobsters that died shortly after being in the laboratory, showed mostly peak three but their overall values were much less than those of the injected lobsters.

The influence of contact pressure, moisture, and compression time on the performance of cotton anti-contamination clothing

The objectives of this research were (1) to study the effect of contact pressure, compression time, and liquid (moisture content of the fabric) on the transfer by sliding contact of non-fixed surface contamination to protective clothing constructed from uncoated, woven fabrics, (2) to study the effect of contact pressure, compression time, and liquid content on the subsequent penetration through the fabric, and (3) to determine if varying the type of contaminant changes the effect of contact pressure, compression time, and liquid content on the transfer by sliding contact and penetration of non-fixed surface contamination. ^ It was found that the combined influence of the liquid (moisture content of the fabric), load (contact pressure), compression time, and their interactions significantly influenced the penetration of all three test agents, sucrose- 14C, triolein-3H, and starch-14C through 100% cotton fabric. The combined influence of the statistically significant main effects and their interactions increased the penetration of triolein- 3H by 32,548%, sucrose-14C by 7,006%, and starch- 14C by 1,900%. ^

An evaluation of a Lake Houston tributary, Cypress Creek, for contamination and water quality

Introduction. Lake Houston serves as a reservoir for both recreational and drinking water for residents of Houston, Texas, and the metropolitan area. The Texas Commission on Environmental Quality (TCEQ) expressed concerns about the water quality and increasing amounts of pathogenic bacteria in Lake Houston (3). The objective of this investigation is to evaluate water quality for the presence of bacteria, nitrates, nitrites, carbon, phosphorus, dissolved oxygen, pH, turbidity, suspended solids, dissolved solids, and chlorine in Cypress Creek. The aims of this project are to analyze samples of water from Cypress Creek and to render a quantitative and graphical representation of the results. The collected information will allow for a better understanding of the aqueous environment in Cypress Creek.^ Methods. Water samples were collected in August 2009 and analyzed in the field and at UTSPH laboratory by spectrophotometry and other methods. Mapping software was utilized to develop novel maps of the sample sites using coordinates attained with the Global Positioning System (GPS). Sample sites and concentrations were mapped using Geographic Information System (GIS) software and correlated with permitted outfalls and other land use characteristic.^ Results. All areas sampled were positive for the presence of total coliform and Escherichia coli (E. coli). The presences of other water contaminants varied at each location in Cypress Creek but were under the maximum allowable limits designated by the Texas Commission on Environmental Quality. However, dissolved oxygen concentrations were elevated above the TCEQ limit of 5.0 mg/L at majority of the sites. One site had near-limit concentration of nitrates at 9.8 mg/L. Land use above this site included farm land, agricultural land, golf course, parks, residential neighborhoods, and nine permitted TCEQ effluent discharge sites within 0.5 miles upstream.^ Significance. Lake Houston and its tributary, Cypress Creek, are used as recreational waters where individuals may become exposed to microbial contamination. Lake Houston also is the source of drinking water for much of Houston/Harris and Galveston Counties. This research identified the presence of microbial contaminates in Cypress Creek above TCEQ regulatory requirements. Other water quality variables measured were in line with TCEQ regulations except for near-limit for nitrate at sample site #10, at Jarvis and Timberlake in Cypress Texas.^

Evaluation of environmental contamination of Clostridium difficile associated diarrhea in hospital rooms at St. Luke's Episcopal Hospital (SLEH) and review of literature on environmental sampling

The study was carried out at St. Luke's Episcopal Hospital to evaluate environmental contamination of Clostridium difficile in the infected patient rooms. Samples were collected from the high risk areas and were immediately cultured for the presence of Clostridium difficile . Lack of microbial typing prevented the study of molecular characterization of the Clostridium difficile isolates obtained led to a change in the study hypothesis. The study found a positivity of 10% among 50 Hospital rooms sampled for the presence of Clostridium difficile. The study provided data that led to recommendations that routine environmental sampling be carried in the hospital rooms in which patients with CDAD are housed and that effective environmental disinfection methods are used. The study also recommended molecular typing methods to allow characterization of the CD strains isolated from patients and environmental sampling to determine their type, similarity and origin.^

Fecal coliform contamination in child day care environments in Houston, Texas

Outbreaks of diarrhea are common among children in day care centers (DCC). Enteropathogens associated with these outbreaks are spread by the fecal-oral route through contaminated hands or environmental objects. This prospective study was undertaken to determine the prevalence of fecal coliform (FC) contamination in the DCC environment. Ten rooms in 6 DCC housing 121 children $<$2 years of age were studied for 13 weeks. Inanimate objects (1275), toy balls (724), and hands (954) were cultured 1-3 times per week. FC contamination was common during each week of study and was significantly (p $<$ 0.05) greater for objects, toy balls, and hands of children in toddler compared to infant rooms. In 5 rooms in which clothes were worn over diapers, there was a significantly lower prevalence of FC of toy balls (p $<$ 0.005), inanimate objects (p $<$ 0.05), and hands of children (p $<$ 0.001) and caregivers (p $<$ 0.05) when compared to rooms in which overclothes were not worn. Occurrence of diarrhea was significantly associated with increased contamination of caregivers' and children's hands. Using plasmid analysis of trimethoprim (TMP)-resistant Escherichia coli, stool and environmental isolates from individual DCC rooms had the same plasmid patterns, which were unique to each center. In summary, FC of environmental isolates and hands of children and caregivers in DCC is common; toy balls can serve as sentinels of contamination; FC can be significantly decreased by use of clothes worn over diapers; and plasmid analysis of E. coli strains showed the same patterns from stool and environmental isolates. ^

Characterization of fecal contamination targeting 16S rRNA bacteroides molecular markers in the Santa Cruz River, Arizona

Understanding the origins, transport and fate of contamination is essential to effective management of water resources and public health. Individuals and organizations with management responsibilities need to understand the risks to ecosystems and to humans from contact with contamination. Managers also need to understand how key contaminants vary over time and space in order to design and prioritize mitigation strategies. Tumacacori National Historic Park (NHP) is responsible for management of its water resources for the benefit of the park and for the health of its visitors. The existence of microbial contaminants in the park poses risks that must be considered in park planning and operations. The water quality laboratory at the Maricopa Agricultural Center (in collaboration with stakeholder groups and individuals located in the ADEQ-targeted watersheds) identified biological changes in surface water quality in impaired reaches rivers to determine the sources of Escherichia coli (E. coli); bacteria utilizing innovative water quality microbial/bacterial source tracking methods. The end goal was to support targeted watershed groups and ADEQ towards E. coli reductions. In the field monitoring was conducted by the selected targeted watershed groups in conjunction with The University of Arizona Maricopa Agricultural Center Water Quality Laboratory. This consisted of collecting samples for Bacteroides testing from multiple locations on select impaired reaches, to determine contamination resulting from cattle, human recreation, and other contributions. Such testing was performed in conjunction with high flow and base flow conditions in order to accurately portray water quality conditions and variations. Microbial monitoring was conducted by The University of Arizona Water Quality Laboratory at the Maricopa Agricultural Center using genetic typing to differentiate among two categories of Bacteroides: human and all (total). Testing used microbial detection methodologies and molecular source tracking techniques.^