2-Phenylethylamine formation by enterococci in vitro

The ability of enterococci to form PEA in vitro was investigated on a test strain Fs 202 of species Ec. faecalis from cheese. 22 enterococcal strains were isolated from foodstuff: nine strains from cheese, three strains from minced pork, seven strains from carcasses of pigs, two strains from chicken carcasses and one strain from cattle carcasses. The enterococci were examined in a test medium with additives of L-phenylalanine, L-tyrosine and dextrose. The amount of formed PEA was measured in periods of 24 h in test strain Fs 202 using RP-HPLC. Simultaneously, the pH-value and the number of microbes were determined at start and 72 h. The tested strains formed maximal or significant PEA amounts in test medium at 30 °C incubation temperature in a period of 72 h. In the same period strains without PEA formation were detected. A regular and intensive PEA formation was found by six Ec. faecalis, five Ec. hirae and two Ec. faecium strains. Ec. faecium could form only moderate PEA amounts. Amine traces or no PEA at all were detected for one Ec. faecium strain, three Ec. durans strains, two Ec. gallinarum strains and one Ec. casseliflavus strain. Potential starter organisms or probiotic strains should be tested in vitro at 30 °C for 72 hours for ability to form PEA. For toxicological reasons, it is important that those strains not have any ability to form PEA.     

Captan residue reduction in apples as a result of rinsing and peeling

Apples, treated with captan for disease control in a commercial orchard in Quebec, Canada, were collected and sorted into post-harvest preparation types (no preparation; rinse; rinse and peel). Captan residues were greatest (25.5–5100 ng/g) in apples with no post-harvest preparation and lowest (0.146–136 ng/g) in apples that had been rinsed and peeled prior to extraction and analysis. Residues were significantly lower (p = 0.003) in apples that had been rinsed prior to extraction than in apples with no post-harvest preparation. Similarly, apples subjected to rinsing and peeling had significantly lower captan residues than had apples that had been rinsed alone (p < 0.0001). Although captan residues in rinsed apples were approximately 50% lower than those in apples that received no post-harvest preparation, the reduction associated with peeling of apples was much greater (98%). Estimated mean captan intakes resulting from consumption of raw apples were established and single day intakes, based on apples with no preparation, ranged from 2.58 μg/kg in females >70 years to 9.48 μg/kg for individuals aged three years (at this age no distinction is made between males and females). Mean intakes estimated using rinsed and peeled apples were approximately two orders of magnitude lower than intakes estimated using apples with no post-harvest preparation, demonstrating the effect of post-harvest preparation on captan intakes. Mean captan intake estimates from all post-harvest preparation types were well below the World Health Organization acceptable daily intake of 100 μg/kg/day, based on raw apple consumption.     

Development and evaluation of microarray-based whole-genome hybridization for detection of microorganisms within the context of environmental applications

The detection and identification of microorganisms in natural communities is a great challenge to biologists. Microarray-based genomic technology provides a promising high-throughput alternative to traditional microbial characterization. A novel prototype microarray containing whole genomic DNA, termed community genome array (CGA), was constructed and evaluated. Microarray hybridizations at 55 degrees C using 50% formamide permitted the examined bacteria to be distinguished at the species level, while strain-level differentiation was obtained at hybridization temperatures of 65 or 75 degrees C. The detection limit was estimated to be approximately 0.2 ng with genomic DNA from a single pure culture using a reduced hybridization volume (3 microL). Using mixtures of known amounts of DNA or a known number of cells from 14 or 16 different species, respectively, about 5 ng of genomic DNA or 2.5 x 10(5) cells were detected under the hybridization conditions used. In addition, strong linear relationships were observed between hybridization signal intensity and target DNA concentrations for pure cultures, a mixture of DNA templates, and a population of mixed cells (r2 = 0.95-0.98, P < 0.01). Finally, the prototype CGA revealed differences in microbial community composition in soil, river, and marine sediments. The results suggest that CGA hybridization has potential as a specific, sensitive, and quantitative tool for detection and identification of microorganisms in environmental samples.     

The effects of pre-annealing in either H2 or He on the formation of Fe nanoparticles for growing spin-capable carbon nanotube forests

Pre-annealing in either H₂ or He is shown to have a significant impact on the formation of either Fe nanoparticles or Fe contiguous films. This suggests various ways to form suitable-sized nanoparticles for the growth of well-aligned, spin-capable MWCNT forests. The reduction of the native iron oxide in as-deposited Fe films suppresses the formation of contiguous films, helping to form nanoparticles. In contrast, contiguous films are formed when the native iron oxide is crystallized into hematite, α-Fe₂O₃, by annealing the Fe film in He gas. The reduction of hematite in H₂ gas breaks up the contiguous films into nanoparticles. This break-up of Fe contiguous films into nanoparticles is suppressed by other effects such as Ostwald ripening processes at the forest growth temperature of 780 °C. Understanding the catalyst dynamics for forming either Fe nanoparticles or contiguous films provides ways to control the MWCNT alignment.     

Quality assurance concepts for adhesive bonding of composite aircraft structures – characterisation of adherent surfaces by extended NDT

In order to ensure the performance of adhesively joined load-critical composite structures, suitable technologies are needed to steadily monitor adherent surfaces prior to bonding and to detect adhesion properties of bonded components. A novel class of non-destructive testing (NDT) techniques, classified as extended non-destructive testing (ENDT), is required to ascertain selected physicochemical properties which are important for the performance of adhesive bonds in place of detecting material defects like conventional NDT methods do. The European FP7 project, ‘ENCOMB – Extended non-destructive testing of composite bonds’ aims in the identification, development, adaptation and validation of ENDT methods for characterisation of adherent surfaces and adhesive bond quality. Here, recent NDT techniques such as optically stimulated electron emission (OSEE) and aerosol wetting test (AWT) as well as laser-induced breakdown spectroscopy (LIBS) were advanced and applied in field, and without contacting carbon fibre-reinforced polymer (CFRP) surfaces for detecting different contamination layers such as release agent, moisture or hydraulic oil as well as thermal degradation of CFRP adherent surfaces before performing an adhesive bonding process. Sensitivity and accuracy of these techniques allow distinguishing surface states which are suitable for bonding of CFRP adherents from surface states which are unfavourable for bonding. ENDT using OSEE, AWT and LIBS facilitated the detection of layers of release agent as thin as one nanometre and thin layers resulting from hydraulic oil. OSEE investigations of adherent surfaces before adhesive bonding allowed the indication of all surface states of potential CFRP adherents, which according to previous studies, were related to application scenarios reducing the joint strength of resulting adhesive joints by 20–70%.     

Sewer Discharge Estimation by Stereoscopic Imaging and Synchronized Frame Processing

A system for fully automatic contact‐less image‐based measurement of volumetric flow rate in urban drainage structures is presented. The hardware includes two original equipment manufacturer cameras and a single‐board computer on which our custom image processing software is running. The value of water discharge depends on the surface velocity, water level and channel's geometry. The level of the flow is estimated as the difference between distances from the camera to the water surface and from the camera to the channel's bottom. Camera‐to‐water distance is recovered automatically using large‐scale stereo‐matching, whereas the distance to the channel's bottom is measured upon installation. Surface velocity is calculated using cross‐correlation template matching: individual natural particles in the flow are detected and tracked throughout the sequence of images recorded over a fixed time interval. The relative discharge computation error is lower than 1.34% of the theoretical maximal discharge for a given location, which makes our system competitive to commercial components such as ultrasonic flow meters, while using cheaper technologies.