Determination of the distribution of air and water in porous media by electrical impedance tomography and magneto-electrical imaging

Monitoring the distribution of water content is essential for understanding hydrological processes in the lithosphere and the pedosphere. The movement of water in unsaturated rock formations and in the vadose zone is influenced by different processes (mainly infiltration, evaporation, percolation and capillary flow) which may be rate determining depending on the actual conditions. The interdependence of these processes also strongly influences the transport and distribution of solutes in the pore space. In order to gain a better understanding of the movement and distribution of water in unsaturated media, systematic investigations with non-invasive or minimal invasive methods appear to be most suitable. Studies on the distribution of electrical conductivity can improve risk analysis concerning waste disposals in general and nuclear waste repositories in particular. Induced polarization and magnetic flux density determined with two highly sensitive accessories yield additional information and may allow for better discrimination of coupled flow processes. Electrical impedance tomography (EIT) with 20 current injection and 48 voltage electrodes was used here to monitor the evaporation of tap water from a container filled with sand under laboratory conditions at 20 °C. The results are compared with data obtained by determining spectral induced polarization (SIP) of sand during desaturation in a multi-step outflow equipment. Infiltration processes and evaporation from sand saturated with 0.01 M CaCl₂ were determined by magneto-electrical resistivity imaging technique (MERIT). The results were obtained from a long-term experiment under controlled conditions.     

Standardized code quality benchmarking for improving software maintainability

We provide an overview of the approach developed by the Software Improvement Group for code analysis and quality consulting focused on software maintainability. The approach uses a standardized measurement model based on the ISO/IEC 9126 definition of maintainability and source code metrics. Procedural standardization in evaluation projects further enhances the comparability of results. Individual assessments are stored in a repository that allows any system at hand to be compared to the industry-wide state of the art in code quality and maintainability. When a minimum level of software maintainability is reached, the certification body of TüV Informationstechnik GmbH issues a Trusted Product Maintainability certificate for the software product.     

Wasserbindungskapazit?t und Makrostruktur von Apfelgewebepartikeln

Zusammenfassung Haufwerke aus trockenen Apfelgewebepartikeln mit mittleren Partikelvolumina zwischen 0,3 und 5 mm³ können bis zu 80 g/g Wasser aufnehmen. Der überwiegende Teil dieses Wassers ist in makrocapillaren Haufwerks- und Partikelhohlräumen eingelagert und nur durch sehr geringe Kräfte gebunden. Bereits bei Einwirkung eines Gasdrucks von 2 kPa werden die Partikelhaufwerke stark entwässert. Die Wasserbeladung sinkt auf 20-15 g/g. Die Rehydratation einzelner getrockneter Apfelgewebepartikel ist vom Ausmaß der bei der Zerkleinerung eingetretenen Gewebezerstörung abhängig und kann durch eine der Trocknung vorgelagerte Entwässerung mit Ethanol verbessert werden. Vorentwässerte Partikel mit einem hohen Ethanolgehalt schrumpfen bei der Trocknung im geringeren Ausmaß und besitzen eine hohe Porosität. Solche Partikel binden im rehydratisierten Zustand bis zu 30 g/g Wasser. Nicht mit Ethanol behandelte Partikel binden unter 11 g/g Wasser.

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Water binding capacity and macrostructure of apple tissue particles

Samples (bulk materials) of dry apple tissue particles in a range of particle volume from 0.3 to 5 mm³ can absorb up to 80 g/g water. Most of this water is included in macrocapillary bulk and particle spaces and is bound by very small forces. An external gas pressure of 2 kPa decreases the water content to 20-15 g/g. The rehydration properties of single apple tissue particles depend on the degree of tissue disintegration and can be improved by a dehydration treatment with ethanol before drying. Such pre-dehydrated particles with a high ethanol concentration in the liquid phase show little shrinkage during the drying process and have a high porosity. They retain up to 30 g/g water after rehydration. The water uptake of non-ethanol-treated particles is less than 11 g/g.

     

Three generations of cyclosporine a formulations: an in vitro comparison

When the microemulsion formulation of the critical dose drug cyclosporine A (CsA) (Sandimmun Optoral) was introduced in the mid-1990s, it became clear that this new formulation improves the oral bioavailability of CsA and has a positive influence on its pharmacokinetic variability. Previous studies with the original CsA formulation (Sandimmun) showed that the size of the emulsion droplets and concomitant food intake has an effect on the absorption of CsA from the small intestine when orally administered. It was suggested that these effects might have an influence on the drugs' pharmacokinetic parameters.In this study, we focused on the two above-mentioned aspects and compared the first and second generations of CsA products (Sandimmun, Sandimmun Optoral) to generic CsA formulations by analyzing the contents of cyclosporine A gel capsules with respect to their emulsion droplet and micelle sizes using photon correlation spectroscopy (PCS). We tried to discern any differences in droplet size between different generations of CsA formulations, primarily the second and third generation, through simple physical tests. Because a high fat content food may influence the absorption of CsA, we also determined the distribution of CsA between hydrophilic and lipophilic phases using high-performance liquid chromatography analysis.It became clear that when compared under simple physical conditions, established cyclosporine formulations and new generic products show significant differences in droplet size and distribution between an aqueous phase and a high fat content food. Whether these differences are of clinical relevance remains to be investigated.     

Heat and mass transfer during the coffee drying process

For a better comprehension of heat and mass transfer during the coffee drying process and optimization of the industrial application transport coefficients and coffee properties were determined. Heat transfer coefficients were measured for different air velocities and were found to follow the known dimensionless equations for the flow surrounding a sphere. Thermal conductivities and effective diffusion coefficients were measured as a function of moisture content as well as volume and densities of the coffee beans. The mentioned properties depend directly on the humidity of the coffee beans rather than on the drying conditions. Sorption behaviour was investigated and temperature dependent parameters for the Guggenheimer–Anderson–deBoer-isotherm (GAB) were determined according to the Arrhenius relationship.     

An Engineered Mannoside Presenting Platform: Escherichia coli Adhesion under Static and Dynamic Conditions

The study of the adhesion mechanisms of pathogens to host tissues has gained increased interest as bacterial adhesion is involved in the early stages of surface colonization and infection. Here we describe a platform to study the specific binding of the bacterium Escherichia coli (E. coli) K‐12 strain to molecularly well‐defined surfaces mimicking cellular interfaces. This approach uses a poly(ethylene glycol) brush interface, which displays synthetic determinants of the high mannose N‐linked glycans in a range of densities (3.8 × 10⁴–1.6 × 10⁵ mannosides µm^?2) for the investigation of multivalent interactions with bacteria. The bacterial attachment is mediated by specific interactions between the adhesive protein FimH located on the tip of the bacterial type 1 pili and the mannosylated surfaces. With synthetically engineered mannoses, it is found that the number of strongly adhering bacteria is co‐regulated by many structural physical parameters. Beyond the dependency on carbohydrate density, higher numbers of E. coli attach to the branched trimannose Man(α1–3)(Man(α1–6))Man compared to the monomannose, while larger oligomannoses exposing Man(α1–2) Man at their non reducing end show low binding capacity. The linker used between the mannose moiety and PEG is also affecting the binding efficacy of E. coli. The (hydrophobic) propyl linker results in higher bacteria numbers in comparison to the (hydrophilic) tri(EG), likely a consequence of additional stabilization of the binding complex by hydrophobic interactions. Furthermore, differences are observed in bacteria attachment between stagnant and flow conditions that depend on the type of mannose ligand. Finally, a photolithographic resist lift‐off combined with site‐selective assembly of the glycopolymers is used to produce micropatterns with bacteria colonies confined to defined areas and at controlled colony numbers.     

Plant-derived polyphenols attenuate lipopolysaccharide-induced nitric oxide and tumour necrosis factor production in murine microglia and macrophages

Lipopolysaccharides released during bacterial infections induce the expression of pro-inflammatory cytokines and lead to complications such as neuronal damage in the CNS and septic shock in the periphery. While the initial infection is treated by antibiotics, anti-inflammatory agents would be advantageous add-on medications. In order to identify such compounds, we have compared 29 commercially available polyphenol-containing plant extracts and pure compounds for their ability to prevent LPS-induced up-regulation of NO production. Among the botanical extracts, bearberry and grape seed were the most active preparations, exhibiting IC(50) values of around 20 mug/mL. Among the pure compounds, IC(50) values for apigenin, diosmetin and silybin were 15, 19 and 12 muM, in N-11 murine microglia, and 7, 16 and 25 muM, in RAW 264.7 murine macrophages, respectively. In addition, these flavonoids were also able to down-regulate LPS-induced tumour necrosis factor production. Structure-activity relationships of the flavonoids demonstrated three distinct principles: (i) flavonoid-aglycons are more potent than the corresponding glycosides, (ii) flavonoids with a 4'-OH substitution in the B-ring are more potent than those with a 3'-OH-4'-methoxy substitution, (iii) flavonoids of the flavone type (with a C2=C3 double bond) are more potent than those of the flavanone type (with a at C2-C3 single bond).     

Comparative studies of a real-time PCR method and three enzyme-linked immunosorbent assays for the detection of central nervous system tissues in meat products

The removal of certain central nervous system (CNS) tissues (part of the bovine spongiform encephalopathy risk material) from the food chain is one of the highest priority tasks associated with avoiding contamination of the human food chain with the agent of bovine spongiform encephalopathy. A recently developed real-time PCR assay and three commercially available enzyme-linked immunosorbent assays (ELISAs) for the detection of CNS tissues in minced meat and three types of heat-treated sausages were evaluated. Bovine brain was used for spiking of internal reference material, and its detectability was examined during storage times of 12 months (for frozen minced meat and liver sausage) and 24 months (for sausages treated with medium and high heat). The real-time PCR method and both ELISA kits detected 0.1% CNS tissue in frozen minced meat and 0.1 or 1% CNS tissue in heat-treated meat products. The detectability of the amplified mRNA target region with the PCR assay was similar to the detectability of antigen by the ELISAs. Because the real-time PCR method also can be used to distinguish cattle, ovine, and caprine CNS tissues from porcine CNS tissues, it seems to be suitable as a routine diagnostic test for the sensitive and specific detection of CNS tissues in meat and meat products.     

Ultrathin Polydopamine Films with Phospholipid Nanodiscs Containing a Glycophorin A Domain

Cellular membranes have long served as an inspiration for nanomaterial research. The preparation of ultrathin polydopamine (PDA) films with integrated protein pores containing phospholipids and an embedded domain of a membrane protein glycophorin A as simplified cell membrane mimics is reported. Large area, ultrathin PDA films are obtained by electropolymerization on gold surfaces with 10–18 nm thickness and dimensions of up to 2.5 cm². The films are transferred from gold to various other substrates such as nylon mesh, silicon, or substrates containing holes in the micrometer range, and they remain intact even after transfer. The novel transfer technique gives access to freestanding PDA films that remain stable even at the air interfaces with elastic moduli of ≈6–12 GPa, which are higher than any other PDA films reported before. As the PDA film thickness is within the range of cellular membranes, monodisperse protein nanopores, so‐called “nanodiscs,” are integrated as functional entities. These nanodisc‐containing PDA films can serve as semi‐permeable films, in which the embedded pores control material transport. In the future, these simplified cell membrane mimics may offer structural investigations of the embedded membrane proteins to receive an improved understanding of protein‐mediated transport processes in cellular membranes.