Search results for "Contamination"
showing 10 items of 916 documents
Perturbative calculation of spin-orbit splittings using the equation-of-motion ionization-potential coupled-cluster ansatz.
2008
Spin-orbit splittings for (2)Pi states are calculated within coupled-cluster (CC) theory via first-order degenerate perturbation theory. Using the equation-of-motion CC variant for ionization potentials (EOMIP-CC), the two components of the considered (2)Pi state are treated in a balanced way by generating both radical states via annihilation of one electron out of the CC wave function of the corresponding anion. We report on the implementation of the described approach within the CC singles and doubles approximation. To ensure computational efficiency, an atomic mean-field approximation for the spin-orbit integrals is used, resulting in a formulation in terms of one-electron transition-den…
Assessment of the ecotoxicity of phytotreatment substrate soil as landfill cover material for in-situ leachate management
2019
Phytotreatment capping in closed landfills is a promising, cost-effective, in situ option for sustainable leachate treatment and might be synergistically coupled with energy crops to produce renewable energy (e.g.: biodiesel or bioethanol). This study proposes to use 0.30 m of soil as growing substrate for plants cultivated on the temporary cover of closed landfills. Once the leachate phytotreatment process is no longer required, 0.70 m of the same soil would be added to attain the final top cover configuration. This solution would entail saving the costs of excavation and backfilling. However, worsening of the initial soil quality due to potential contaminant transfer from the liquid to th…
Presence of pathogenic bacteria in ice cubes and evaluation of their survival in different systems
2017
In this study, 60 samples of ice cubes produced at different levels (domestic, restaurant and industrial facilities), within a restricted geographical area, were investigated for their general microbiological characteristics through the analysis of populations other than enteric bacteria. Total mesophilic bacteria were in the range 1.01 Ã 102â9.55 Ã 103, 3.12 Ã 102â6.31 Ã 103and 1.30 Ã 102â3.99 Ã 103CFU/100Â mL of thawed ice from domestic freezer (DF), stock boxes (SB) for self-production performed with ice machines in bars and pubs, and from sales packages (SP) of industrial productions, respectively. Some DF and SP samples were negative for the presence of total psychrotrophic…
Effect of saliva contamination on bracket failure with a self-etching primer: A prospective controlled clinical trial
2010
Introduction The aim of this study was to evaluate in vivo the effect of saliva contamination at different stages of the bonding procedure on the bond failure rate and the adhesive remaining on teeth after debonding brackets bonded with a hydrophilic self-etching primer (Transbond Plus self-etching primer [TSEP], 3M Unitek, Monrovia, Calif). Methods This was a prospective controlled clinical trial. The sample consisted of 46 patients with similar treatment plans and mechanotherapies. Stainless steel brackets (n = 531) were bonded with TSEP. The patients were divided into 2 groups: contamination with saliva before TSEP application and contamination with saliva after TSEP application. In both…
Quantification of Listeria monocytogenes in salads by real time quantitative PCR
2005
Abstract A real time quantitative PCR (RTQ-PCR) was carried out purifying DNA extracts of Listeria monocytogenes using a High Pure Listeria Sample Preparation Kit and quantifying in a LightCycler system with hybridisation probes. A standard curve was constructed with serial dilutions. A range linear relationship, from 10 to 10 5 L. monocytogenes colony forming units (CFU), was observed between threshold cycle ( C t ) and logarithmic concentration of the serial dilutions. The assay was linear in a range from 10 to 10 5 L. monocytogenes CFU and the coefficient of determination ( r 2 ) was > 0.98. RTQ-PCR presented an efficiency of > 85%. The accuracy of the PCR-based assay, expressed as % bia…
Selective, Highly Sensitive, and Rapid Detection of Genomic DNA by Using Gated Materials:MycoplasmaDetection
2013
The coupling of gated-indicator delivery with highly specific biochemical recognition is an innovative strategy for the detection of DNA sequences, able to compete with classical methods which need PCR amplification, in important areas such as point-of-care diagnostics or detection of specific biological contaminations with pathogens. Such comparatively simple and cheap yet highly selective and sensitive assays hold promise for use in less-developed areas of the world.
Cumulative Effects of Short-Term Polymetal Contamination on Soil Bacterial Community Structure
2006
ABSTRACT In this study we evaluated the short-term effects of copper, cadmium, and mercury, added singly or in combination at different doses, on soil bacterial community structure using the bacterial automated ribosomal intergenic spacer analysis (B-ARISA) fingerprinting technique. Principal-component analysis of B-ARISA profiles allowed us to deduce the following order of impact: (Cu + Cd + Hg) >> Hg ≥ Cd > Cu. These results demonstrated that there was a cumulative effect of metal toxicity. Furthermore, the trend of modifications was consistent with the “hump-backed” relationships between biological diversity and disturbance described by Giller et al. (K. E. Giller, E. Witler, an…
A multiplex RTi-PCR reaction for simultaneous detection of Escherichia coli O157:H7, Salmonella spp. and Staphylococcus aureus on fresh, minimally pr…
2007
In this work, a new multiplex single-tube real-time PCR approach is presented for the detection of Escherichia coli O157:H7, Salmonella spp. and Staphylococcus aureus, three of the more frequent food-borne bacterial pathogens that are usually investigated in a variety of food matrices. The study includes the design and specificity testing, of a new primer and probe specific for Salmonella spp. Reaction conditions were adjusted for the simultaneous amplification and detection of specific fragments in the beta-glucuronidase (uidA, E. coli) and Thermonulease (nuc, Sta. aureus) genes, and in the replication origin sequence (oriC, Salmonella spp.). Melting-curve analysis using a SYBR Green I RTi…
Use of a species-specific multiplex PCR for the identification of pediococci.
2008
In this study, the 23S rRNA genes of nine different Pediococcus type strains were sequenced. By using a multiple sequence alignment with 23S rDNA sequences of related lactic acid bacteria two primer pairs were constructed, one for the general identification of the genus Pediococcus and one for the identification of the atypical species, P. dextrinicus. Furthermore, a primer set for a rapid multiplex PCR identification of the eight typical Pediococcus species was developed. With this technique, the species P. damnosus, P. parvulus, P. inopinatus, P. cellicola, P. pentosaceus, P. acidilactici, P. claussenii, and P. stilesii could be discriminated simultaneously in a single PCR. Experiments wi…
pilF polymorphism-based real-time PCR to distinguish Vibrio vulnificus strains of human health relevance
2012
The Gram-negative bacterium Vibrio vulnificus is a common inhabitant of estuarine environments. Globally, V. vulnificus is a significant foodborne pathogen capable of causing necrotizing wound infections and primary septicemia, and is a leading cause of seafood-related mortality. Unfortunately, molecular methods for the detection and enumeration of pathogenic V. vulnificus are hampered by the genetically diverse nature of this pathogen, the range of different biotypes capable of infecting humans and aquatic animals, and the fact that V. vulnificus contains pathogenic as well as non-pathogenic variants. Here we report an alternative approach utilizing the development of a real-time PCR assay…