Species richness, structural diversity and species composition in meadows created by visitors of a botanical garden in Switzerland

Biodiversity is an increasingly important criterion in designing ecological compensation areas and urban green areas. However, little is known about how important biodiversity is to the general public. This paper presents the results of two complementary studies investigating the meadow preferences of visitors to a botanical garden in Switzerland. In the first study, 152 people were asked to create their own favourite meadow patch by selecting 25 out of 779 local wild plants (54 species) that were displayed in flowerpots. In the second study, 143 people were asked with the help of a written questionnaire to imagine a bare piece of land the size of 100 m × 100 m close to their place of living and mentally create the meadow of their dreams. In both cases, study participants assembled meadows that were species-rich and rich in structural diversity (expressed by plant height and leaf forms). Moreover, they explicitly stated diversity as their main assemblage criterion. Although study participants favoured plants with large or colourful flowers, only a third of all plants in the meadows created with real plants were flowering and in people's imagined meadows grasses were frequently included, indicating that people like diverse meadows consisting of a green matrix with some colourful flowers.     

Permeability of low molecular weight organics through nanofiltration membranes

The removal of natural organic matter (NOM) using nanofiltration (NF) is increasingly becoming an option for drinking water treatment. Low molecular weight (LMW) organic compounds are nevertheless only partially retained by such membranes. Bacterial regrowth and biofilm formation in the drinking water distribution system is favoured by the presence of such compounds, which in this context are considered as the assimilable organic carbon (AOC). In this study, the question of whether NF produces microbiologically stable water was addressed. Two NF membranes (cut-off of about 300 Da) were tested with different natural and synthetic water samples in a cross-flow filtration unit. NOM was characterised by liquid chromatography with organic carbon detection (LC-OCD) using a size-exclusion column in addition to specific organic acid measurements, while AOC was measured in a batch growth bioassay.Similarly to high molecular weight organic compounds like polysaccharides or humic substances that have a permeability lower than 1%, charged LMW organic compounds were efficiently retained by the NF membranes tested and showed a permeability lower than 3%. However, LMW neutrals and hydrophobic organic compounds permeate to a higher extent through the membranes and have a permeability of up to 6% and 12%, respectively. Furthermore, AOC was poorly retained by NF and the apparent AOC concentration measured in the permeated water was above the proposed limit for microbiologically stable water. This indicates that the drinking water produced by NF might be biologically unstable in the distribution system. Nevertheless, in comparison with the raw water, NF significantly reduced the AOC concentration.     

Optimization of PCR-based methods for rapid detection of Campylobacter jejuni, Campylobacter coli and Yersinia enterocolitica serovar 0:3 in wastewater samples

PCR-based methods were evaluated for their adequacy to assess the removal of pathogens from wastewater samples. For the development and optimization of the methods, samples were taken at two different sites from two different constructed wetlands. Campylobacter jejuni/coli and Yersinia enterocolitica serogroup 0:3 were selected as model pathogens and Enterococcus faecalis as a standard microbiological indicator. The chosen PCR protocols were optimized for wastewater DNA extracts in order to obtain high sensitivity and reproducibility independently of the background flora. All PCR protocols were successfully performed and reproducible with a background of up to 10(10) nontarget cells per reaction. Five cells of Y. enterocolitica, 50 cells of C. jejuni/coli, and 500 cells of E. faecalis per 100ml treated water could be detected. The method detection limit in the settled wastewater was higher: 200 cells per 100ml for Y. enterocolitica, 2000 cells per 100ml for C. jejuni/coli, and 20,000 cells per 100ml for E. faecalis. C. jejuni/coli and Y. enterocolitica PCRs were adapted to municipal wastewater, with higher loads of potential PCR inhibitors. Sensitivity was lower for this type of wastewater: 200 cells of Y. enterocolitica and 2000 cells of C. jejuni/coli were detected per 100ml treated wastewater, 2500 cells of Y. enterocolitica and 25,000 cells of C. jejuni/coli per 100ml settled wastewater. The developed PCR methods enable the detection of C. jejuni/coli, Y. enterocolitica serogroup 0:3 and E. faecalis within 12h. They show specificity, reproducibility and low detection limits for the investigated pathogens.     

Modeling retention and selectivity as a function of pH and column temperature in liquid chromatography

In reversed-phase liquid chromatography (RPLC), the retention of weak acids and bases is a sigmoidal function of the mobile-phase pH. Therefore, pH is a key chromatographic variable to optimize retention and selectivity. Furthermore, at an eluent pH close to the pKa of the solute, the dependence of ionization of the buffer and solute on temperature can be used to improve chromatographic separations involving ionizable solutes by an adequate handling of column temperature. In this paper, we derive a general equation for the prediction of the retentive behavior of ionizable compounds upon simultaneous changes in mobile-phase pH and column temperature. Four experiments, two limiting pH values and two temperatures, provide the input data that allow predictions in the whole range of these two variables, based on the thermodynamic fundamentals of the involved equilibria. Also, the study demonstrates the significant role that the choice of the buffer compound would have on selectivity factors in RPLC at temperatures higher than 25 degrees C.     

Comparison of biocompatibility and adsorption properties of different plastics for advanced microfluidic cell and tissue culture models

Microfluidic technology is providing new routes toward advanced cell and tissue culture models to better understand human biology and disease. Many advanced devices have been made from poly(dimethylsiloxane) (PDMS) to enable experiments, for example, to study drug metabolism by use of precision-cut liver slices, that are not possible with conventional systems. However, PDMS, a silicone rubber material, is very hydrophobic and tends to exhibit significant adsorption and absorption of hydrophobic drugs and their metabolites. Although glass could be used as an alternative, thermoplastics are better from a cost and fabrication perspective. Thermoplastic polymers (plastics) allow easy surface treatment and are generally transparent and biocompatible. This study focuses on the fabrication of biocompatible microfluidic devices with low adsorption properties from the thermoplastics poly(methyl methacrylate) (PMMA), polystyrene (PS), polycarbonate (PC), and cyclic olefin copolymer (COC) as alternatives for PDMS devices. Thermoplastic surfaces were oxidized using UV-generated ozone or oxygen plasma to reduce adsorption of hydrophobic compounds. Surface hydrophilicity was assessed over 4 weeks by measuring the contact angle of water on the surface. The adsorption of 7-ethoxycoumarin, testosterone, and their metabolites was also determined after UV-ozone treatment. Biocompatibility was assessed by culturing human hepatoma (HepG2) cells on treated surfaces. Comparison of the adsorption properties and biocompatibility of devices in different plastics revealed that only UV-ozone-treated PC and COC devices satisfied both criteria. This paper lays an important foundation that will help researchers make informed decisions with respect to the materials they select for microfluidic cell-based culture experiments.     

Formation of a heterojunction by electrophoretic deposition of CdTe/CdSe nanoparticles from an exhaustible source

Fast and well controlled electrophoretic deposition of CdTe and CdSe nanoparticle (CdTe-np and CdSe-np) layers and nanoparticle layer systems from an exhaustible source has been demonstrated. Using a small volume of pyridine based nanoparticle suspensions with varying concentrations, these were completely drained of nanoparticles during deposition. Our proposed approach is well suited to a practical realization of engineering materials with different band gaps for various promising applications such as fabrication of nanodevices. The formation of a charge selective contact across the CdTe-np/CdSe-np heterojunction was investigated by surface photovoltage methods and evidence of the separation of charge carriers at a CdTe-/CdSe-np heterojunction in‐between was demonstrated.     

Mechanical behaviour and 3D stress analysis of multi-layered wooden beams made with welded-through wood dowels

This paper presents experimental and numerical investigations on multi-layered timber beams using welded-through wood dowels in place of traditional poly(vinyl acetate) (PVAc)-adhesives (or metallic nails). Four-layer beams were constructed with varying numbers of dowels, in each, and then loaded using four-points bending tests to evaluate the mechanical performance of these beams. The practical difficulties encountered in constructing deeper multi-layer beams are discussed and possible solutions which have been employed for the purpose of this work, and proved successful are presented. In order to investigate thoroughly the full potential of multi-layered beams with a very limited number of experimental studies, a 3D FE model has been presented, validated against experimental results and then used to study some influential parameters. The results showed that a reasonable bending stiffness of multi-layered beams is achievable with a good combination of material and geometric parameters.     

Inhibition of mammary tumor growth using lysyl oxidase-targeting nanoparticles to modify extracellular matrix

A cancer nanotherapeutic has been developed that targets the extracellular matrix (ECM)-modifying enzyme lysyl oxidase (LOX) and alters the ECM structure. Poly(d,l-lactide-co-glycolide) nanoparticles (～220 nm) coated with a LOX inhibitory antibody bind to ECM and suppress mammary cancer cell growth and invasion in vitro as well as tumor expansion in vivo, with greater efficiency than soluble anti-LOX antibody. This nanomaterials approach opens a new path for treating cancer with higher efficacy and decreased side effects.