Miniaturized ionization gas sensors from single metal oxide nanowires

Gas detection experiments were performed with individual tin dioxide (SnO2) nanowires specifically configured to observe surface ion (SI) emission response towards representative analyte species. These devices were found to work at much lower temperatures (T≈280 °C) and bias voltages (V≈2 V) than their micro-counterparts, thereby demonstrating the inherent potential of individual nanostructures in building functional nanodevices. High selectivity of our miniaturized sensors emerges from the dissimilar sensing mechanisms of those typical of standard resistive-type sensors (RES). Therefore, by employing this detection principle (SI) together with RES measurements, better selectivity than that observed in standard metal oxide sensors could be demonstrated. Simplicity and specificity of the gas detection as well as low-power consumption make these single nanowire devices promising technological alternatives to overcome the major drawbacks of solid-state sensor technologies.     

Entwurf von Flüssigkeitsbehältern

Design of Liquid Retaining Structures – Remarks on the Rules of the Guideline “Watertight Concrete” The use of watertight concrete structures is regulated by the guideline “Watertight Concrete” of the German Committee of Reinforced Concrete, especially requirements on the serviceability limit states. The scope of the guideline is valid for liquid retaining structures too. The essential characteristic of those structures is their defined tightness. Design concepts in order to fullfill requirements on durability of concrete tanks are discussed. Moreover, recommendations due to the design of moderate prestressed reinforced concrete tanks are given, containing the durable filling of planned cracks. Design aspects of the European Standard EC 2 Part 3 are discussed too.     

ESBL-producing E. coli in Austrian sewage sludge

The aim of this study was to investigate the degree of contamination of sewage sludge with ESBL-producing Escherichia coli strains and the effectiveness of different sewage sludge treatment methods.Monthly sewage sludge samples were collected between January and September 2009 in 5 different sewage treatment plants and tested for the presence of ESBL E. coli. In addition, the number of colony forming units (CFU) of E. coli and coliform bacteria before and after the different sludge treatment methods (aerobic/anaerobic digestion, lime stabilization, and thermal treatment) was investigated.Of the 72 sewage sludge samples investigated, ESBL-positive E. coli were found in 44 (61.1%) sewage sludge samples. The classification of β-lactamase groups was carried out in 15 strains resulting in the detection of 2 different groups (CTX-M and TEM) of bla genes. All 15 of them had a CTX-M gene and 4 of these strains furthermore carried a TEM gene.With regard to the CFU of E. coli and coliform bacteria, thermal treatment and lime stabilization following dehydration sufficiently reduced pathogen concentrations. The plants using merely stabilization and dehydration showed an increase of E. coli and coliform bacteria and thus also an increase in ESBL-producing E. coli.     

Entwicklung und Erprobung eines Verfahrens zur Untergrundentsäuerung von Kippengrundwässern

Sulfate-reducing processes were initiated in an aquifer with AMD-laden groundwater orthogonally to the located main groundwater flow direction. Groundwater was intermittently circulated between two wells. Substrate (methanol) and nutrients were added to this flow. After one year a sulphate-reducing reactor was formed in the aquifer, that precipitated FeS and decreased the acidity. These effects could still be observed one year after cessation of substrate amendment.     

Dichten von Rissen in wasserundurchlässigen Bauwerken aus Beton

Sealing Cracks in Water impermeable Concrete Structures Cracks prejudice the serviceability of a water proofed concrete structure. The paper gives an overview of post‐measures of waterproofing in consideration of the current national codes. The filling of cracks under pressure and the applicability of the different injection products are discussed in detail. Consequences for the practice are deducible from this.     

Tuning Molecular Self‐Assembly on Bulk Insulator Surfaces by Anchoring of the Organic Building Blocks

Molecular self‐assembly constitutes a versatile strategy for creating functional structures on surfaces. Tuning the subtle balance between intermolecular and molecule‐surface interactions allows structure formation to be tailored at the single‐molecule level. While metal surfaces usually exhibit interaction strengths in an energy range that favors molecular self‐assembly, dielectric surfaces having low surface energies often lack sufficient interactions with adsorbed molecules. As a consequence, application‐relevant, bulk insulating materials pose significant challenges when considering them as supporting substrates for molecular self‐assembly. Here, the current status of molecular self‐assembly on surfaces of wide‐bandgap dielectric crystals, investigated under ultrahigh vacuum conditions at room temperature, is reviewed. To address the major issues currently limiting the applicability of molecular self‐assembly principles in the case of dielectric surfaces, a systematic discussion of general strategies is provided for anchoring organic molecules to bulk insulating materials.     

Determination of CFTR densities in erythrocyte plasma membranes using recognition imaging

CFTR (cystic fibrosis transmembrane conductance regulator) is a cAMP-regulated chloride (Cl(-)) channel that plays an important role in salt and fluid movement across epithelia. Cystic fibrosis (CF), the most common genetic disease among Caucasians, is caused by mutations in the gene encoding CFTR. The most predominant mutation, F508del, disturbs CFTR protein trafficking, resulting in a reduced number of CFTR in the plasma membrane. Recent studies indicate that CFTR is not only found in epithelia but also in human erythrocytes. Although considerable attempts have been made to quantify CFTR in cells, conclusions on numbers of CFTR molecules localized in the plasma membrane have been drawn indirectly. AFM has the power to provide the needed information, since both sub-molecular spatial resolution and direct protein recognition via antibody-antigen interaction can be observed. We performed a quantification study of the CFTR copies in erythrocyte membranes at the single molecule level, and compared the difference between healthy donors and CF patients. We detected that the number of CFTR molecules is reduced by 70% in erythrocytes of cystic fibrosis patients.     

Influence of dynamic stimulation,visual perception and individual susceptibility to car sickness during controlled stop-and-go driving

Forschung im Ingenieurwesen - The enjoyment and usage of highly automated vehicles might be reduced by motion sickness. This study addresses the influencing factors of dynamic stimulation, visual...     

Metal–Organic Framework Nanoparticles Induce Pyroptosis in Cells Controlled by the Extracellular pH

Ion homeostasis is essential for cellular survival, and elevated concentrations of specific ions are used to start distinct forms of programmed cell death. However, investigating the influence of certain ions on cells in a controlled way has been hampered due to the tight regulation of ion import by cells. Here, it is shown that lipid-coated iron-based metal–organic framework nanoparticles are able to deliver and release high amounts of iron ions into cells. While high concentrations of iron often trigger ferroptosis, here, the released iron induces pyroptosis, a form of cell death involving the immune system. The iron release occurs only in slightly acidic extracellular environments restricting cell death to cells in acidic microenvironments and allowing for external control. The release mechanism is based on endocytosis facilitated by the lipid-coating followed by degradation of the nanoparticle in the lysosome via cysteine-mediated reduction, which is enhanced in slightly acidic extracellular environment. Thus, a new functionality of hybrid nanoparticles is demonstrated, which uses their nanoarchitecture to facilitate controlled ion delivery into cells. Based on the selectivity for acidic microenvironments, the described nanoparticles may also be used for immunotherapy: the nanoparticles may directly affect the primary tumor and the induced pyroptosis activates the immune system.     

Simple colorimetric method for quantification of surface carboxy groups on polymer particles

We present a novel, simple, and fast colorimetric method to quantify the total number of carboxy groups on polymer microparticle and nanoparticle surfaces. This method exploits that small divalent transition metal cations (M(2+) = Ni(2+), Co(2+), Cd(2+)) are efficiently bound to these surface functional groups, which allows their extraction by a single centrifugation step. Remaining M(2+) in the supernatant is subsequently quantified spectrophotometrically after addition of the metal ion indicator pyrocatechol violet, for which Ni(2+) was identified to be the most suitable transition metal cation. We demonstrate that the difference between added and detected M(2+) is nicely correlated to the number of surface carboxy groups as determined by conductometry, thereby affording a validated measure for the trueness of this procedure. The variation coefficient of ~5% found in reproducibility studies underlines the potential of this novel method that can find conceivable applications for the characterization of different types of poly(carboxylic acid)-functionalized materials, e.g., for quality control by manufacturers of such materials.