Reduced contamination and infection via inhibition of adhesion of foodborne bacteria to abiotic polystyrene and biotic amoeba surfaces

Adhesion of foodborne pathogens to materials of industrial surfaces is an important step in their transmission through the food chain. Adhesion is also a prerequisite for bacterial colonisation within a host, to enable intracellular invasion. We define a strategy to reduce contamination and infection by Listeria monocytogenes, Campylobacter jejuni and Escherichia coli using an ethanol extract of Alpinia katsumadai seeds (AlpE) and epigallocatechin gallate (EGCG) as anti‐adhesive agents. We show for the first time that AlpE and EGCG reduce adhesion of individual cultures to polystyrene (AlpE, up to 10.6%; EGCG, up to 39.7%) and to the amoeba Acanthamoeba castellanii (AlpE, up to 52.6%; EGCG, up to 53.4%). The combination of AlpE/EGCG significantly reduced C. jejuni adherence to the abiotic (45.5%) and biotic (52.2%) surfaces. Thus, using natural agents from plants at low doses, we can potentially reduce the primary source of food contamination and a frequent source of infections.     

Adaptation of a Rare Earth Element Pre-concentration Method for Water Enriched in Al,Ca, Fe,and Mg

The use of rare earth elements (REE) as process indicators in water-rock interactions can be hampered by the fact that samples with high concentrations of total dissolved solids require dilution before ICP-MS analysis, which can lower REE concentrations close to or below detection limits. A pre-concentration method originally developed for chloride-dominated water with very low REE concentrations was tested for and adapted to sulfate-rich water from a mining-affected area with a pH of 6 and high concentrations of Ca, Fe, Mg, and sometimes Al. The adapted approach proved easy to implement in the field and produced very good recoveries and reliable REE patterns. Two factors, sample volume and ionic strength, were tested. Pre-concentration with high sample volumes (1000 mL) resulted in poor recoveries (1.8?±?0.3?% for La up to 17.8?±?0.6?% for Yb). When the sample volume was reduced to 25 mL, much better recoveries were achieved. Reducing the ionic strength by diluting the sample 1:100 or 1:1000 resulted in comparable recoveries than the approach with reduced sample volume, indicating that sample volume was more important than ionic strength. Among the tested competing elements, high concentrations of Ca, Fe, and Mg resulted in loss of light REE (La-Nd), while Al was found to reduce the recovery of all REE. Also for water with high concentrations of Ca and Fe and very low REE concentrations (ppt-range), especially La results should be considered with care after pre-concentration, and be neglected in REE patterns if necessary.     

Microwave Dielectric Behavior of Wet Soil-Part II: Dielectric Mixing Models

This paper is the second in a series evaluating the microwave dielectric behavior of soil-water mixtures as a function of water content and soil textural composition. Part II draws upon the data presented in Part 1 [13] to develop appropriate empirical and theoretical dielectric mixing models for the 1.4-to 18-GHz region. A semiempirical mixing model based upon the index of refraction is presented, requiring only easily ascertained soil physical parameters such as volumetric moisture and soil textural composition as inputs. In addition, a theoretical model accounting explicitly for the presence of a hydration layer of bound water adjacent to hydrophilic soil particle surfaces is presented. A four-component dielectric mixing model treats the soil-water system as a host medium of dry soil solids containing randomly distributed and randomly oriented disc-shaped inclusions of bound water, bulk water, and air. The bulk water component is considered to be dependent upon frequency, temperature, and salinity. The soil solution is differentiated by means of a soil physical model into 1) a bound component and 2) a bulk soil solution. The performance of each model is evaluated as a function of soil moisture, soil texture, and frequency, using the dielectric measurements of five soils ranging from sandy loam to silty clay (as presented in Part I [13]) at frequencies between 1.4 and 18 GHz. The semiempirical mixing model yields an excellent fit to the measured data at frequencies above 4 GHz. At 1.     

On the cytocompatibility of biodegradable Fe-based alloys

Biodegradable iron-based alloys are potential candidates for application as temporary implant material. This study summarizes the design strategy applied in the development of biodegradable Fe–Mn–C–Pd alloys and describes the key factors which make them suitable for medical applications. The study's in vitro cytotoxicity tests using human umbilical vein endothelial cells revealed acceptable cytocompatibility based on the alloys' eluates. An analysis of the eluates revealed that Fe is predominantly bound in insoluble degradation products, whereas a considerable amount of Mn is in solution. The investigation's results are discussed using dose–response curves for the main alloying elements Fe and Mn. They show that it is mainly Mn which limits the cytocompatibility of the alloys. The study also supplies a summary of the alloying elements' influence on metabolic processes.The results and discussion presented are considered important and instructive for future alloy development. The Fe-based alloys developed show an advantageous combination of microstructural, mechanical and biological properties, which makes them interesting as degradable implant material.     

The effect of realistic curing temperature on the strength and E-modulus of concrete

The strength and E-modulus of concrete are decisive parameters when it comes to ultimate limit state design, serviceability limit state design, and early age crack assessment. The properties of concrete are generally determined in the laboratory under 20 °C isothermal conditions and then used as the basis for calculations under realistic temperature conditions. It is well-known, however, that the curing temperature affects both the rate of property development in concrete and the “final value” of a given property. The current study investigated the effect of a realistic temperature history on the compressive cube strength, the tensile strength, and the tensile E-modulus for two concretes, a reference concrete and a fly ash concrete. Concrete specimens were subjected to either (1) 20 °C isothermal curing conditions, or (2) realistic temperature curing conditions for 14 days and then 20 °C isothermal conditions, until they were tested after 28 and 91 days. Parallel tests performed in a Temperature-Stress Testing Machine were also used to evaluate the results. The reference concrete showed a general reduction in strength and E-modulus when subjected to a realistic curing temperature, whereas the fly ash concrete showed an 11% increase in the 28-day E-modulus when cured under realistic temperature conditions. Furthermore, in both isothermal and realistic curing temperature conditions, the fly ash concrete showed a pronounced property development beyond 28 days, which could not be described by the material model currently used.     

Limitations of electrospray ionization of fulvic and humic acids as visible from size exclusion chromatography with organic carbon and mass spectrometric detection

A method was developed to link size exclusion chromatography electrospray ionization mass spectrometry (SEC-ESI-MS) analyses of fulvic and humic acids with SEC and organic carbon detection (SEC-OCD), the latter providing an absolute measure of the amount of organic matter eluting from the SEC column. This approach allows us to determine which molecular weight fraction of the complex polydisperse mixtures is detectable by ESI-MS. It could be shown that the cone voltage setting for the ESI interface has strong impact on ESI-MS detection. Using conventional settings for low molecular weight compounds, the high molecular weight (HMW) compounds are hardly amenable to ESI-MS. With increasing cone voltage, an increasing signal intensity is obtained for the HMW fraction that elutes at shorter retention times. However, mostly fragment ions are obtained under these conditions. Thus, the range of compounds amenable to ESI-MS analysis is restricted by the limited stability of the fulvic and humic acid molecules of higher molecular weight in the electrospray process rather than by the mass spectrometer used. Compounds above 1000 amu are hardly visible as intact ions. However, insight into structural characteristics of these compounds can be gained by investigating their fragment ions by SEC-ESI-MS. The use of SEC-OCD parallel to SEC-MS helps to assess and optimize the detection potential of ESI-MS for polydisperse mixtures.     

Inventor collaboration over distance: a comparison of academic and corporate patents

Patenting is often done in collaboration with other inventors to integrate complementary and additional knowledge. The paper takes a spatial view of this issue and analyses the distances between inventors of German patents. We compare the distances between invention teams of German patent applications from 1993–2006 and distinguish between academic and corporate teams and those consisting of researchers from both domains (‘mixed teams’). Due to their different institutional backgrounds different types of proximity guide their spatial search for partners. The basic finding is that regional collaboration clearly prevails. However, the distance between collaborating inventors of corporate patents exceeds that of inventors of academic patents, but the largest distances can be found in science–industry collaborative patents. When excluding directly neighboured collaboration, which is likely to be in-house collaboration, the differences between academic and corporate teams vanish, but mixed teams still overcome longer distances.     

Development and critical evaluation of fluorescent chloride nanosensors

In this study, we describe the preparation and evaluation of new fluorescent sensor nanoparticles for the ratiometric measurement of chloride concentrations. Both a chloride-sensitive dye (lucigenin) and a reference dye (sulforhodamine derivative) were incorporated into polyacrylamide nanoparticles via inverse microemulsion polymerization and investigated for their response to chloride ions in buffered suspension as well as in living cells. The fluorescence intensity of lucigenin reversibly decreased in the presence of chloride ions due to a collisional quenching process, which can be described with the Stern-Volmer equation. The determined Stern-Volmer constant K SV for the quenching of lucigenin incorporated into particles was found to be 53 M (-1) and is considerably smaller than the Stern-Volmer constant for quenching of free lucigenin ( K SV = 250 M (-1)) under the same conditions. To test the nanosensors in living cells, we incorporated them into Chinese hamster ovary cells and mouse fibroblasts by using the conventional lipofectamin technique and monitored the response to changing chloride concentrations in the cell.     

Mineralised collagen—an artificial,extracellular bone matrix—improves osteogenic differentiation of bone marrow stromal cells

In the field of bone tissue engineering there is a high demand on bone graft materials which promote bone formation. By combination of collagen type I with nanocrystalline hydroxyapatite (HA) we generated a resorbable material which structure and composition is close to those of the extracellular bone matrix. This nanocomposit material was produced in a biomimetic process in which collagen fibril assembly and mineralisation with hydroxyapatite occur simultaneously. In this study the proliferation and osteogenic differentiation of human bone marrow-derived stromal cells (hBMSC) on membranes of biomimetically mineralised collagen type I was investigated. To this end, we optimised biochemical assays for determination of cell number and alkaline phosphatase activity corresponding to the special properties of this biomaterial. For cell experiments hBMSC were seeded on the mineralised collagen membranes and cultivated over 35 days, both in static and perfusion culture, in the presence and absence of dexamethasone, β-glycerophosphate and ascorbate. Compared to cells grown on tissue culture polystyrene we found attenuated proliferation rates, but markedly increased activity of alkaline phosphatase on the mineralised collagen indicating its promoting effect on the osteogenic differentiation of hBMSC. Therefore this bone-like material may act as a suitable artificial extracellular matrix for bone tissue engineering. Perfusion of the 2D cell matrix constructs with cell culture medium did not improve proliferation and osteogenic differentiation of the hBMSC. Anne Bernhardt and Anja Lode contributed equally to this paper     

Adaptable and Reprogrammable Surfaces

Establishing control over chemical reactions on interfaces is a key challenge in contemporary surface and materials science, in particular when introducing well‐defined functionalities in a reversible fashion. Reprogrammable, adaptable and functional interfaces require sophisticated chemistries to precisely equip them with specific functionalities having tailored properties. In the last decade, reversible chemistries—both covalent and noncovalent—have paved the way to precision functionalize 2 or 3D structures that provide both spatial and temporal control. A critical literature assessment reveals that methodologies for writing and erasing substrates exist, yet are still far from reaching their full potential. It is thus critical to assess the current status and to identify avenues to overcome the existing limitations. Herein, the current state‐of‐the‐art in the field of reversible chemistry on surfaces is surveyed, while concomitantly identifying the challenges—not only synthetic but also in current surface characterization methods. The potential within reversible chemistry on surfaces to function as true writeable memories devices is identified, and the latest developments in readout technologies are discussed. Finally, we explore how spatial and temporal control over reversible, light‐induced chemistries has the potential to drive the future of functional interface design, especially when combined with powerful laser lithographic applications.