Two fosmid libraries, totaling 13,200 clones, were obtained from bioreactor sludge of petroleum refinery wastewater treatment system. The library screening based on PCR and biological activity assays ...revealed more than 400 positive clones for phenol degradation. From these, 100 clones were randomly selected for pyrosequencing in order to evaluate the genetic potential of the microorganisms present in wastewater treatment plant for biodegradation, focusing mainly on novel genes and pathways of phenol and aromatic compound degradation. The sequence analysis of selected clones yielded 129,635 reads at an estimated 17-fold coverage. The phylogenetic analysis showed Burkholderiales and Rhodocyclales as the most abundant orders among the selected fosmid clones. The MG-RAST analysis revealed a broad metabolic profile with important functions for wastewater treatment, including metabolism of aromatic compounds, nitrogen, sulphur and phosphorus. The predicted 2,276 proteins included phenol hydroxylases and cathecol 2,3- dioxygenases, involved in the catabolism of aromatic compounds, such as phenol, byphenol, benzoate and phenylpropanoid. The sequencing of one fosmid insert of 33 kb unraveled the gene that permitted the host, Escherichia coli EPI300, to grow in the presence of aromatic compounds. Additionally, the comparison of the whole fosmid sequence against bacterial genomes deposited in GenBank showed that about 90% of sequence showed no identity to known sequences of Proteobacteria deposited in the NCBI database. This study surveyed the functional potential of fosmid clones for aromatic compound degradation and contributed to our knowledge of the biodegradative capacity and pathways of microbial assemblages present in refinery wastewater treatment system.
The wastewater from oil production can be exceptionally saline and contain a complex mixture of hydrocarbons, many of which are highly toxic. This study aimed to identify and characterize 141 ...halophilic bacteria isolated from production water and activated sludge from Marine Terminal Almirante Barroso (Brazil) and evaluate their potential for biosurfactant production and biodegradation of distinct petroleum hydrocarbons. Sequencing and phylogenetic analysis of the 16S rRNA gene revealed that the halophilic bacteria retrieved are distributed among 20 genera and four phyla (Proteobacteria, Firmicutes, Actinobacteria and Flavobacteria). RAPD fingerprinting was used to differentiate isolates at the infra-specific level, revealing 79 different genetic profiles. GC-MS analysis carried out with eight strains confirmed their ability to efficiently degrade alkanes and aromatic compounds under halophilic conditions, with preference for aromatic degradation. Eleven strains showed significant ability for reduction of the surface tension (from 72 to 40 mN/m) and for emulsification (up to 71%) of four different types of oils (mineral, soybean, diesel and kerosene). Results gathered in this study demonstrate a high taxonomic and genetic diversity of the halophilic bacterial strains isolated from the oil terminal samples and an outstanding potential for further use in biotechnological processes such as biosurfactant production or bioremediation.
•The halophilic bacteria retrieved are distributed among 20 genera and four phyla.•Eleven strains showed significant ability for reduction of the surface tension.•Eight bacteria showed great capacity to degrade different hydrocarbons.•There was no direct relationship between the catabolic genes and biodegradation.•There was potential for reduction of surface tension and emulsification.
Water generated during oil exploration is chemically complex and contains high concentrations of ammonium and, in some cases, high salinity. The most common way to remove ammonium from effluent is a ...biological process, which can be performed by different routes and different groups of microorganisms. However, the presence of salts in the effluents could be an inhibiting factor for biological processes, interfering directly with treatment. This study aimed to evaluate changes in the profile of a microbial community involved in the process of ammonium removal when subjected to a gradual increase of salt (NaCl), in which the complete inhibition of the ammonium removal process occurred at 125 g L
−1
NaCl. During the sludge acclimatization process, samples were collected and submitted to denaturing gradient gel electrophoresis (DGGE) and massive sequencing of the 16S ribosomal RNA (rRNA) genes. As the salt concentration increased in the reactor, a change in the microbial community was observed by the DGGE band profiles. As a result, there was a reduction in the presence of bacterial populations, and an increase in archaeal populations was found. The sequencing data suggested that ammonium removal in the reactor was carried out by different metabolic routes by autotrophic nitrifying bacteria, such as
Nitrosococcus
,
Nitrosomonas
,
Nitrosovibrio
,
Nitrospira
, and
Nitrococcus
; ammonium-oxidizing archaea
Candidatus nitrosoarchaeum
; ANAMMOX microorganisms, such as
Candidatus brocadia, Candidatus kuenenia
, and
Candidatus scalindua
; and microorganisms with the potential to be heterotrophic nitrifying, such as
Paracoccus
spp.,
Pseudomonas
spp.,
Bacillus
spp.,
Marinobacter
sp., and
Alcaligenes
spp.
The development of dedicated coils and new magnetic resonance imaging (MRI) sequences has led to an increase in image resolution and a reduction in artifacts. Consequently, numerous studies have ...demonstrated the utility of MRI as a nonionizing alternative to cone-beam computed tomographic imaging. The aim of this systematic review was to evaluate the accuracy of MRI in clinical applications in endodontics.
A literature search was conducted using PubMed, Embase, Scopus, and Web of Science. The inclusion criteria encompassed studies evaluating MRI applications in endodontics, covering tooth and root canal anatomy, root canal working length, pulp vitality and regeneration, the effect of caries on dental pulp, guided endodontics, periapical lesions, and root cracks/fractures. The selected studies examined both ex vivo and in vivo human teeth using clinical MRI units. Two researchers independently screened the studies, applied the eligibility criteria, and assessed the potential risk of bias using the revised QUADAS-2 tool (Bristol Medical School, University of Bristol, UK).
A total of 18 studies were included in this systematic review, demonstrating that the use of MRI has a high diagnostic value in endodontics. In the evaluation of tooth and root canal anatomy, pulp vitality and regeneration, the effect of caries on dental pulp, periapical lesions, and root cracks/fractures, MRI’s accuracy is comparable to or even higher than reference standards such as cone-beam computed tomographic imaging, micro–computed tomographic imaging, and histology.
MRI has high potential accuracy for diagnosing various clinical endodontic tasks, except for root canal length, size of caries, and periapical lesion dimensions, which are overestimated in MRI.
► Cellulose was modified with aminoethanethiol. ► The kinetic sorption occurs in pseudo-second-order model. ► The excellent pH’s for interaction was 2 and 9. ► The experimental data was adjusted to ...Langmuir model. ► New material could be employed as low-cost material for the removal of anionic dye.
The natural biopolymer cellulose was initially chlorinated at the 6 carbon with a degree of substitution (DS) 0.99±0.01 and then reacted with aminoethanethiol to form a modified compound with different basic centers, and this material was characterized by elemental analysis, XRD, TG, FTIR and 13C NMR. The matrix obtained was effective in removing red reactive anionic dye in an aqueous medium at pH values of 2 and 9. The equilibrium time of adsorption obtained was approximately 100min (pH 2) and 160min (pH 9), and the kinetics for both systems followed a pseudo-second-order model. The adsorption isotherms at different pH levels at three different temperatures obeyed the Langmuir model, and the maximum adsorption capacities were 78mgg−1 (pH 2) and 26mgg−1 (pH 9), and the interaction was electrostatic and hydrogen bonds and/or covalent, respectively.
Aim
To evaluate the effects of progressive root canal enlargements on the unprepared surface area and remaining dentine thickness of three‐rooted maxillary first premolars with different root ...configurations.
Methodology
Thirty three‐rooted maxillary first premolars with three root configurations (n = 10) were selected and scanned in a micro‐CT device. The root canals were sequentially enlarged with rotary instruments sizes 30.02 (step 1), 30.04 (step 2) and 30.06 (step 3). After each step, a new scan was taken. Analysed parameters included morphometric measurements (length, volume and surface area), number of static voxels and minimal dentine thickness. Statistical analyses were performed with one‐way anova post hoc Tukey tests and paired sample t‐test at a significance level of 5%.
Results
No statistical differences were observed amongst groups regarding the morphometric parameters and static voxels (p > .05). The minimal dentine thickness of the distobuccal root significantly changed depending on the root configuration (p < .05), whilst no differences were observed in the other roots (p > .05). A great variation in the position of the minimal dentine thickness was observed after preparation. Overall, mean percentage reduction in dentine thickness was higher in the buccal roots than in the palatal root (p < .05). In the mesiobuccal and distobuccal root, the number of slices with minimal dentine thickness lower than 0.05 mm increases 2 to 3 times and 3 to 4 times, respectively, from steps 1 to 3.
Conclusions
Instruments sizes 30.02 and 30.04 can be safely and effectively used to enlarge the buccal and palatal canals of three‐rooted maxillary first premolars.
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•Review of the most recent and relevant achievements concerning ASR process.•Conditioning factors, diagnostic and preventive measures of ASR were debated.•Proper models to monitor ASR ...is a major concern for concrete service life prediction.•Several efforts have been devoted in understanding the fundamentals of ASR.
In the last few decades, the alkali–silica reaction (ASR) has been reported as one of the major concrete concerns regarding durability, leading to high maintenance and reconstruction costs. The occurrence of ASR in numerous concrete infrastructures all over the world points to the need for research regarding measures for its detection in an initial stage (and further mitigation) either in new or existing structures. Furthermore, the chemical and physical mechanisms for ASR remain poorly understood. This lack of knowledge leads to incapacity to assess risk, cost-effectively predict service life, and efficiently mitigate the deterioration process due to ASR in concrete structures.
This manuscript aims to review the most recent and relevant achievements and the existing knowledge concerning the reaction mechanisms of ASR. Additionally, this manuscript is focused on the conditioning factors, diagnostic and prognostic methodologies, preventive measures and test methods (including their limitations) of ASR conducted at an academic level. The perspectives for future research challenges are also identified and debated.
Vilanova WV, Carvalho‐Junior JR, Alfredo E, Sousa‐Neto MD, Silva‐Sousa YTC. Effect of intracanal irrigants on the bond strength of epoxy resin‐based and methacrylate resin‐based sealers to root canal ...walls. International Endodontic Journal, 45, 42–48, 2012.
Aim To assess the bond strength of Epiphany and AH Plus sealers to root canal walls using a push‐out test after use of several endodontic irrigants.
Methodology Roots of 100 maxillary canines were sectioned horizontally 5 mm below the cemento‐enamel junction to provide 4‐mm‐thick dentine disks that were embedded in acrylic resin and had their root canals prepared with a tapered bur (larger diameter = 2.70 mm; smaller diameter = 2.30 mm; length = 4 mm). The specimens were randomly assigned to five groups (n = 20) according to the dentine surface treatment: I – 1% NaOCl (30 min); II – 1% NaOCl (30 min) + 17% EDTA (5 min); III – 17% EDTA (30 min); IV – 24% EDTA gel (30 min); V – 2% chlorhexidine gluconate (CHX) gel (30 min). In each group, two specimens were prepared for scanning electron microscopy to examine the surface of root canal dentine after use of each irrigant. The other 18 specimens were filled with AH plus (n = 9) or Epiphany (n = 9) and subjected to a push‐out test in an Instron machine. Data (in MPa) were subjected to statistical analysis by two‐way anova and post‐hoc Tukey–Kramer test (P < 0.05).
Results AH Plus had a significantly higher bond strength (8.74 ± 2.75) than Epiphany (6.74 ± 3.97) (P < 0.05). One per cent NaOCl/17% EDTA was associated with significantly higher bond strength values (10.88 ± 3.05) than the other irrigants (P < 0.05). Seventeen per cent EDTA (8.75 ± 1.75), 24% EDTA gel (7.48 ± 3.48) and 2% CHX gel (7.89 ± 3.41) had intermediate values that were not significantly different from each other (P > 0.05). One per cent NaOCl was associated with the lowest mean values (3.70 ± 0.86) (P < 0.05). The interaction between surface treatment and sealer revealed significantly higher bond strength for 24% EDTA gel with AH Plus, 2% CHX gel with AH Plus and 1%NaOCl/17%EDTA with Epiphany (P < 0.05).
Conclusion Except for 1% NaOCl, the removal of smear layer with the other irrigants increased the bond strength of AH Plus to intracanal dentine. The use of 1% NaOCl for 30 min with 17% EDTA as final irrigant for 5 min increased the bond strength of Epiphany.
•Sensitivity heterogeneity of severe acute respiratory syndrome coronavirus-2 serological tests.•Maximum sensitivity achieved 21 days from symptoms onset.•COVID-19 clinical outcome is associated with ...different immunoglobulins levels.
Commercial availability of serological tests to evaluate immunoglobulins (Ig) targeting severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has grown exponentially since the start of the coronavirus disease 2019 (COVID-19) outbreak. Thorough validation of these tests is important before use as epidemiological tools to infer seroprevalence in specific populations and as diagnostic tools to complement molecular approaches (e.g., quantitative reverse transcription-polymerase chain reaction).
Commercial serological tests from 11 suppliers were assayed side-by-side using 126 samples from SARS-CoV-2-infected inpatients and 36 from healthy and HIV-infected individuals.
The majority of the tests assayed have >95% specificity. For the sensitivity calculation, samples were stratified by days since symptoms onset; sensitivity peaks at 16–21 days for IgM and IgA (maximum 91.2%, Euroimmun) and, dependant on the test, at 16–21 or >21 days for IgG (maximum 94.1%, Snibe). Data from semiquantitative tests show that patients with a severe clinical presentation have lower levels of Ig targeting SARS-CoV-2 at <10 days since symptoms onset and higher levels at >21 days, compared to patients with a non-severe presentation.
This study highlights the heterogeneity of sensitivity and generally high specificity of the serological tests and establishes a basis for their usefulness to complement diagnostic techniques and population seroprevalence studies.
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