The performance of SAS-super-180 air sampler and settle plates for assessing viable fungal particles in the air of dry-cured meat production facility

Performances of SAS-super-180 air sampler and settle plates were investigated for the assessment of airborne fungal food contamination. Air samples were taken from processing rooms of a dry-cured production facility and outdoors. Fungal colonies and numbers of species were counted and compared. Quantitatively, the air sampler showed higher numbers of species and mean CFU/plate compared to settle plates. Qualitatively, the two methods showed similar dominating fungal genera and species associated with dry-cured meat products. The study showed settle plates could provide important qualitative information for food processing plants where airborne fungi associated with food products are the targets.     

Emphasizing some little-used theorems in introductory networkanalysis

This paper promotes the use of some little-used but most valuable theorems that are available to students in introductory network analysis: the voltage and current shifting theorems; the voltage and current source theorems; the reduction theorem; and the substitution theorem. Examples illustrate how these theorems can be used to solve for one or more variables in the many networks that contain dependent as well as independent sources. Network simplification techniques are maximized and the use of equations is minimized. A more extensive use of the duality concept is also recommended     

Towards a robotic plasma spraying operation using vision

An uncalibrated, vision-guided robotic system, based on the method of camera-space manipulation, has been developed to reduce the time and cost associated with teaching a robot a suitable trajectory for plasma coating. The system achieves a high level of precision in both position and orientation control of a 6-DOF robotic arm     

The presence of Penicillium and Penicillium mycotoxins in food wastes

A total of 97 samples (48 summer and 49 winter) of food waste from private households were investigated for Penicillium and for mycotoxins. Twenty-five Penicillium species were isolated and Penicillium crustosum, Penicillium brevicompactum, Penicillium chrysogenum, Penicillium expansum, Penicillium roqueforti, Penicillium spinulosum, Penicillium viridicatum, Penicillium commune, Penicillium citrinum and Penicillium solitum were, in decreasing order, the most frequently identified species. Mycotoxins produced by several of these species, including mycophenolic acid, roquefortine C, penitrems A-F and thomitrems A and E, were detected. Of the 48 summer samples, 36 were severely infected and contained more than 10(5) colony forming units (CFU) Penicillium/g sample. The levels of mycotoxins in these samples were in the range 75-19000 microg/kg mycophenolic acid, 40-920 microg/kg roquefortine C, 35-7500 microg/kg penitrem A, 20-2100 microg/kg thomitrem A and 20-3300 microg/kg thomitrem E. Of the 49 winter samples, only one was found to contain mycophenolic acid (4800 microg/kg) and roquefortine C (190 microg/kg), and this sample was severely infected with P. roqueforti. Thirty samples of food waste collected from the food manufacturing industry were also investigated. The number of Penicillium in these samples was between 10(5) and 10(6) colony forming units (CFU)/g sample. Seven of these samples contained mycophenolic acid ranging from 50 to 600 microg/kg and three of these samples also contained roquefortine C in the range 100-250 microg/kg.     

Tafel slopes used in monitoring of copper corrosion in a bentonite/groundwater environment

The harmonic analysis, the polarization resistance, and the noise resistance methods have been applied in an effort to monitor corrosion of pure copper in a bentonite/groundwater environment with commercially available equipment. Without the need to use a reference electrode, the first method supplies not only an estimate of the corrosion rate, but also estimates of Tafel slopes required by the other methods. The recorded corrosion rate is overestimated but to a varying degree. While the recorded corrosion rates for the first two methods give quite similar values far below 3 μm/year, the electrochemical noise resistance method gives considerably higher values.     

Superparamagnetic Twist‐Type Actuators with Shape‐Independent Magnetic Properties and Surface Functionalization for Advanced Biomedical Applications

Directed nanoparticle self‐organization and two‐photon polymerization are combined to enable three‐dimensional soft‐magnetic microactuators with complex shapes and shape‐independent magnetic properties. Based on the proposed approach, single and double twist‐type swimming microrobots with programmed magnetic anisotropy are demonstrated, and their swimming properties in DI‐water are characterized. The fabricated devices are actuated using weak rotating magnetic fields and are capable of performing wobble‐free corkscrew propulsion. Single twist‐type actuators possess an increase in surface area in excess of 150% over helical actuators with similar feature size without compromising the forward velocity of over one body length per second. A generic and facile combination of glycine grafting and subsequent protein immobilization exploits the actuator's increased surface area, providing for a swimming microrobotic platform with enhanced load capacity desirable for future biomedical applications. Successful surface modification is confirmed by FITC fluorescence.     

Modelling aspects for finite element analysis of ship vibration

The paper describes the present state-of-the-art in analyses of ship vibration and elaborates on the difficulties regarding the finite element modelling.Some suggestions to enable better modelling of the structure, dependent on the aims of the analyses, the accuracy of input data, time and cost are given.It is shown that the main resonant frequencies of global and local structures may be predicted with sufficient accuracy, and a good indication of the forced response level may be obtained at the design stage.     

Elastic Properties and Structure of Interpenetrating Boron Carbide/Aluminum Multiphase Composites

We study the elastic moduli and structure of boron carbide/aluminum (B₄C/Al) multiphase composites using rigorous bounding and experimental characterization techniques. We demonstrate that rigorous bounds on the effective moduli are useful in that they can accurately predict (i) the effective elastic moduli, given the phase moduli and volume fractions, or (ii) the phase moduli (volume fractions), given the effective moduli and phase volume fractions (moduli). Using the best available rigorous bounds on the effective elastic moduli of multiphase composites involving volume-fraction information, we are able to predict the bulk and shear moduli of the Al₄BC phase, a reaction product that forms during heat treatment. These theoretical predictions are in very good agreement with recent experimental measurements of the moduli of the Al₄BC phase. Moreover, we evaluate more-refined bounds involving three-point structural correlation functions by extracting such information from an image of a sample of the B₄C/Al composite. Although experimental data for the effective moduli are unavailable for this sample, our predictions of the effective moduli based on three-point bounds should be quite accurate.     

A simulation study of the combined thermoelectric extracellular stimulation of the sciatic nerve of the Xenopus laevis: the localized transient heat block

The electrical behavior of the Xenopus laevis nerve fibers was studied when combined electrical (cuff electrodes) and optical (infrared laser, low power sub-5?mW) stimulations are applied. Assuming that the main effect of the laser irradiation on the nerve tissue is the localized temperature increase, this paper analyzes and gives new insights into the function of the combined thermoelectric stimulation on both excitation and blocking of the nerve action potentials (AP). The calculations involve a finite-element model (COMSOL) to represent the electrical properties of the nerve and cuff. Electric-field distribution along the nerve was computed for the given stimulation current profile and imported into a NEURON model, which was built to simulate the electrical behavior of myelinated nerve fiber under extracellular stimulation. The main result of this study of combined thermoelectric stimulation showed that local temperature increase, for the given electric field, can create a transient block of both the generation and propagation of the APs. Some preliminary experimental data in support of this conclusion are also shown.     

Occurrence and fate of corrosion-induced zinc in runoff water from external structures

This paper comprises data from an extensive cross-disciplinary research project aiming to elucidate the environmental fate of corrosion-induced zinc release from external structures. It includes an exposure assessment that provide long-term runoff rates, concentrations and chemical speciation of zinc, from 14 zinc-based materials exposed during 5 years in Stockholm, Sweden, and an effect assessment including bioavailability and ecotoxicity measurements, both at the immediate release situation and after soil interaction. Runoff rates of total zinc ranged from 0.07 to 2.5 g Znm-2 yr-1 with zinc primarily released as the free ion for all materials investigated. The average effect concentration, causing a 50% growth reduction after 72 h to the green algae Raphidocelis subcapitata, was at the immediate release situation 69 microg ZnL-1. Upon interaction of runoff water with soil, which simulated 18 to 34 years of exposure, the total zinc concentration was significantly reduced, from milligram per litre to microgram per litre levels. Simultaneously, the most bioavailable fraction of zinc in runoff, the hydrated zinc(II)-ion, decreased from more than 95% to about 30%. The major fraction, 98-99%, of the introduced total zinc concentration in the runoff water was retained within the soil. As long as the soil retention capacity was not reached, this resulted in zinc concentrations in the percolate water transported through the soil layer, close to background values and below growth inhibition concentrations for the green algae investigated. Zinc retained in soil was to a large extent (85-99.9%) extractable with EDTA, and available for plant uptake after 5 to 7 months of ageing.