Development of Cu- and/or phosphonium-based polymeric biocidal materials and their potential application in antifouling paints

The synthesis and characterization of a series of biocidal polymeric materials for potential antifouling submarine applications are presented. The polymeric backbone of these materials contains anionic units, such as styrene sulfonate, and/or acrylate or maleate units. The hydrophobic/hydrophilic nature of these polymers was, furthermore, tuned through copolymerization with hydrophobic units, such as vinyl acetate or styrene. The biocidal species, Cu²⁺ ions and/or phosphonium cations, were incorporated through electrostatic and/or coordination interactions, depending on the nature of the polymeric backbone. It was observed that the release of Cu²⁺ ions in water from the Cu²⁺-containing materials is controlled by the hydrophobic/hydrophilic balance of the polymeric backbone. The prepared biocidal polymeric materials were incorporated into two paint formulations, based on a rosin or a vinylic matrix. The erosion properties of the biocidal paints under accelerated laboratory conditions were evaluated using scanning electron microscopy. It is found that the antifouling performance is related to the release of biocidal species. The most efficient materials are those containing Cu²⁺ ions or combining both Cu²⁺ and phosphonium cations.     

Side-line tunable laser transmitter for differential absorption lidar measurements of CO2: design and application to atmospheric measurements

A 2 microm wavelength, 90 mJ, 5 Hz pulsed Ho laser is described with wavelength control to precisely tune and lock the wavelength at a desired offset up to 2.9 GHz from the center of a CO(2) absorption line. Once detuned from the line center the laser wavelength is actively locked to keep the wavelength within 1.9 MHz standard deviation about the setpoint. This wavelength control allows optimization of the optical depth for a differential absorption lidar (DIAL) measuring atmospheric CO(2) concentrations. The laser transmitter has been coupled with a coherent heterodyne receiver for measurements of CO(2) concentration using aerosol backscatter; wind and aerosols are also measured with the same lidar and provide useful additional information on atmospheric structure. Range-resolved CO(2) measurements were made with <2.4% standard deviation using 500 m range bins and 6.7 min? (1000 pulse pairs) integration time. Measurement of a horizontal column showed a precision of the CO(2) concentration to <0.7% standard deviation using a 30 min? (4500 pulse pairs) integration time, and comparison with a collocated in situ sensor showed the DIAL to measure the same trend of a diurnal variation and to detect shorter time scale CO(2) perturbations. For vertical column measurements the lidar was setup at the WLEF tall tower site in Wisconsin to provide meteorological profiles and to compare the DIAL measurements with the in situ sensors distributed on the tower up to 396 m height. Assuming the DIAL column measurement extending from 153 m altitude to 1353 m altitude should agree with the tower in situ sensor at 396 m altitude, there was a 7.9 ppm rms difference between the DIAL and the in situ sensor using a 30 min? rolling average on the DIAL measurement.     

Towards a novel tensile elastometer for soft tissue

A device designed to determine the tensile properties of soft tissue is proposed for use within the surgical environment. Two pins indent the surface of a bulk of soft tissue and are separated laterally. Using an approximation, the measured load and displacement are mapped to the uniaxial stress and strain of a central volume of material. A correction factor is introduced that depends on geometric factors only for Mooney–Rivlin materials subject to strains of up to 15%, if edge effects are not significant. It is the intention of this study and subsequent studies to design the instrument such that edge effects are minimised. Numerical analysis is employed to test the limits of both the device and the model for Mooney–Rivlin materials. Further analysis is required to determine viability for soft tissue that can display significant anisotropy, material non-homogeneities and highly nonlinear elastic responses. Some initial results towards this end are presented. The method is demonstrated with the use of a prototype device, employing common elastomers to model the soft tissue. An assessment of the accuracy of the prototype and limitations on the use of the device are inferred from the experimental and numerical studies. The modulus of the test materials was subsequently measured to an accuracy of 4% with a spread of 6.5% (using a 95% confidence interval).     

Integrated Management of Non-conventional Water Resources in Anhydrous Islands

Anhydrous islands are dependent either on non-conventional water resources, such as desalinated seawater or reclaimed water from wastewater, or on water importation from the mainland. The latter option is often expensive and non-sustainable. Desalinated water can be used for potable and non-potable water applications, while reclaimed water can be used for non-potable water applications. Thus all water needs can be satisfied by an optimal blend of desalinated and reclaimed water. It is important to calculate the optimal capacities and locations of seawater desalination plants, wastewater treatment plants and water reclamation plants, and to estimate the water/wastewater conveyance system, in order to minimise water production and distribution costs. Mathematical modelling and optimisation techniques can be employed for calculating the optimum scenario: the satisfaction of all water needs at minimum cost. In this article, we have estimated the water demands taking into account water quality for the anhydrous Greek island of Syros, in the Aegean Sea. Syros has been subdivided into 6 regions, taking into account geographical and population distribution criteria. All water needs are to be satisfied by desalinated seawater and reclaimed water. A mixed-integer linear programming algorithm is used here to calculate the optimal scenario (location and capacities of desalination plants and wastewater treatment and water reclamation plants, as well as the desalinated water, reclaimed water and wastewater conveyance infrastructure needed) by minimising the annualised total cost including capital and operating costs.     

Automated segmentation and volumetric analysis of renal cortex,medulla, and pelvis based on non-contrast-enhanced T1- and T2-weighted MR images

Object

The aim of our study was to enable automatic volumetry of the entire kidneys as well as their internal structures (cortex, medulla, and pelvis) from native magnetic resonance imaging (MRI) data sets.

Materials and methods

Segmentation of the entire kidneys and differentiation of their internal structures were performed in 12 healthy volunteers based on non-contrast-enhanced T1- and T2-weighted MR images. Two data sets (each acquired in one breath-hold) were co-registered using a rigid registration algorithm compensating for possible breathing-related displacements. An automatic algorithm based on thresholding and shape detection segmented the kidneys into their compartments and was compared to a manual labeling procedure.

Results

The resulting kidney volumes of the automated segmentation correlated well with those created manually (R ² = 0.96). Average volume errors were determined to be 4.97 ± 4.08 % (entire kidney parenchyma), 7.03 ± 5.56 % (cortex), 12.33 ± 7.35 % (medulla), and 17.57 ± 14.47 % (pelvis). The variation of the kidney volume resulting from the automatic algorithm was found to be 4.76 % based on the measuring of one volunteer with three independent examinations.

Conclusion

The results demonstrate the feasibility of an accurate and repeatable automatic segmentation of the kidneys and their internal structures from non-contrast-enhanced magnetic resonance images.     

Multicenter Collaborative Trial Evaluation of a Method for Detection of Human Adenoviruses in Berry Fruit

The qualitative performance characteristics of a qPCR-based method to detect human adenoviruses in raspberries were determined through a collaborative trial involving 11 European laboratories. The method incorporated a sample process control (murine norovirus) and an internal amplification control. Trial sensitivity or correct identification of 25-g raspberry samples artificially contaminated with between 5?×?10² and 5?×?10⁴?PFU was 98.5%; the accordance and concordance were 97.0%. The positive predictive value was 94.2%. The trial specificity or percentage correct identification of non-artificially contaminated samples was 69.7%; the accordance was 80.0% and the concordance was 61.7%. The negative predictive value was 100%. Application of a method for the detection of human adenoviruses in food samples could be useful for routine monitoring for food safety management. It would help to determine if a route of contamination exists from human source to food supply chain which pathogenic viruses such as norovirus and hepatitis A virus could follow.     

Detection of changes in the cellular composition of Salmonella enterica serovar Typhimurium in the presence of antimicrobial compound(s) of Lactobacillus strains using Fourier transform infrared spectroscopy

It was previously established that Lactobacillus fermentum ACA-DC 179, Lactobacillus plantarum ACA-DC 287 and Lactobacillus plantarum ACA-DC 2350 exhibit antimicrobial activity against Salmonella enterica serovar Typhimurium. In order to further investigate the killing effect of these microorganisms against Salmonella cells, we employed Fourier transform infrared spectroscopy (FT-IR). Salmonella cells were incubated with different concentrated lactobacilli supernatants and their FT-IR spectra were recorded. The second derivative transformation of the original spectra revealed changes in spectral regions corresponding to absorptions of major cellular constituents (e.g. cell wall, cell membrane, and proteins of the cell) among the Salmonella cells treated with the supernatants and those treated with the control samples. Principal component analysis of the second derivative transformed spectra showed that the yet unidentified antimicrobial compound(s) produced by the lactobacilli tested clearly interfered with the fatty acids of the cell membrane, as well as the polysaccharides of the cell wall in Salmonella cells, pointing towards a dual killing mode. Our study shed light for the first time in the anti-Salmonella activity of the particular Lactobacillus strains.     

Effect of water activity on the thermal stability of Thermomyces lanuginosus xylanases for process time–temperature integration

Three strains of the thermophilic fungus Thermomyces lanuginosus were used to produce β-xylanases. The thermal stability of these xylanases at low levels of water activity was studied. Isothermal inactivation experiments were performed in the temperature range of 100–130 °C. Reduction of water activity to 0.63 and as low as 0.13 had a drastic effect on the observed D and z-values. At water activity of 0.13 the D_120 °C and z-values of the three xylanases ranged from 20.4 to 37.6 min and from 23.3 to 28.9 °C, respectively. The applicability of the developed kinetic models was tested under time–temperature profiles representative of typical thermal processes. The developed systems can be applied as time–temperature integrators (TTI) at this high thermal processing range. Calculations demonstrated that the use of a triple xylanase TTI system could provide acceptable F-values prediction for z-values lower than the achieved range.     

A counter-current parallel-plate membrane denuder for the non-specific removal of trace gases

In this paper we present a counter-current parallel-plate membrane diffusion denuder for the non-specific removal of trace gases from an air flow. In this design, gaseous pollutants are removed by diffusing from a sample channel to two purge channels by crossing microporous membranes. In the laboratory, at a sample flow rate of 5 L/min and purge flow rates of 5 L/min each, gas removal efficiencies ranged from 84% for CO to 72% for SF6. Removal efficiencies increased with lower sample flow rate, a higher sample to purge flow rate ratio, a longer channel length, and using molecules with higher diffusion coefficient. Removal efficiencies were, however, not affected by the sample channel height. In addition, gas penetration was exponentially associated with the product of channel length, diffusion coefficient, and the inverse of sample flow rate. Particle losses were significant (10-25% losses) only for particles smaller than 50 nm. In a field evaluation, the denuder's performance was tested with an aerosol produced in a photochemical chamber. The denuder's performance was similar to that observed in the laboratory and was stable over time. Finally, the denuder was tested with a semivolatile organic aerosol. Particle mass losses due to volatilization were about 30%.