Monitoring the “material climate” of wood to predict the potential for decay: Results from in situ measurements on buildings

Moisture has an important influence on fungal decay and therefore on the service life of wooden building components. The applicability of a long-term moisture recording system with glued electrodes was investigated on two different building objects: a cladding with different roof overhangs in Taastrup, Denmark, and a pedestrian timber bridge in Essing, Germany. Results after 2–4 years of in situ measurements are presented in this paper.     

Ultrathin SiO(2) layers on Si(111): preparation, interface gap states and the influence of passivation

An essential prerequisite for the successful application of Si/SiO(2) nanostructures in photovoltaics is the realization of well-defined and abrupt interfaces with low densities of interface gap states. Here, a complete in situ process from preparation and hydrogen passivation to interface gap state analysis by near-UV photoelectron spectroscopy without breaking ultrahigh vacuum (UHV) conditions is introduced. It is demonstrated that by RF plasma oxidation of Si(111) substrates with thermalized neutral oxygen atoms, ultrathin SiO(2) layers can be realized with compositionally and structurally abrupt Si/SiO(2) interfaces and a minimal amount of intermediate oxidation states bridging the transition from Si to SiO(2). Plasma oxidized samples have significantly lower interface gap states than samples oxidized by thermal oxidation at 850?°C. Interface gap state densities were further reduced by in situ hydrogen plasma passivation with nearly thermalized H atoms. The resulting reduction of interface recombination velocity and the increase of effective majority and minority carrier lifetimes are revealed by constant photocurrent measurements and quasi-steady-state photoconductance, respectively.     

Direct transmission detection of tunable mechanical resonance in an individual carbon nanofiber relay

A direct on-chip transmission measurement of the resonance frequency of an individual singly clamped carbon nanofiber relay is reported. The experimental results are in good agreement with a small signal model and show the expected tuning of the resonance frequency with changing bias voltage.     

Reproducible comet assay of amorphous silica nanoparticles detects no genotoxicity

Genotoxicity of commercial colloidal and laboratory-synthesized silica nanoparticles was tested using the single cell gel electrophoresis or Comet assay. By using a carefully developed protocol and careful characterization of the nanoparticle dispersions, Comet assays were performed on 3T3-L1 fibroblasts with 3, 6, and 24 h incubations and 4 or 40 microg/ml of silica nanoparticles. No significant genotoxicity was observed for the nanoparticles tested under the conditions described, and results were independently validated in two separate laboratories, showing that in vitro toxicity testing can be quantitatively reproducible.     

Ultrasensitive PCR and real-time detection from human genomic samples using a bidirectional flow microreactor

In this paper we present a reliable bidirectional flow DNA amplification microreactor for processing real-world genomic samples. This system shares the low-power thermal responsiveness of a continuous flow reactor with the low surface area to volume ratio character of stationary reactors for reducing surface inhibitory effects. Silanization with dimethyldichlorosilane in combination with dynamic surface passivation was used to enhance PCR compatibility and enable efficient amplification. For real-time fragment amplification monitoring we have implemented an epimodal fluorescent detection capability. The passivated bidirectional flow system was ultrasensitive, achieving an RNase P gene detection limit of 24 human genome copies with a reaction efficiency of 77%. This starts to rival the performance of a conventional real-time PCR instrument with a reaction efficiency of 93% and revitalizes flow-through PCR as a viable component of lab on a chip DNA analysis formats.     

Design and evaluation of a new gastrointestinal mucoadhesive patch system containing chitosan-glutathione

Within this study, a novel gastrointestinal patch system was developed and investigated regarding water-absorbing capacity, adhesive properties, in vitro release, unidirectional release and permeation enhancing effect. Water uptake studies revealed that the weight of patch systems with Ch-GSH increased about 44.5 ± 2.3 mg (127%) after 90 min. This patch system remained even after 180 h on the mucosa and released 49.7 ± 0.7% of FD₄ within 8 h. A 2.5-fold higher transport of FD₄ can be obtained in contrast to control. In conclusion this patch system could be an interesting possibility for the transport through the intestinal mucosa of macromolecules which will normally be degraded in the intestinal tract.     

Imaging the Detergency of Single Cotton Fibers with Confocal Microscopy: the Effect of Surfactants and Lipases

Detergency mechanisms of lipids from single cotton fibers were visualized by means of confocal laser scanning microscopy (CLSM). Fibers were soiled with different types of lipids: olive oil, lard and tri-C₁₀, and subsequently stained with the fluorescent probe Nile Red. A surfactant composition of 300 μM C₁₂E₆/LAS (1:2 mol%) was used to mimic the surfactants used in a common washing solution. It was evident from the captured image series that the different kinds of soiling were removed by different mechanisms by the surfactants, depending on the fluidity of the lipid. Roll-up was the main mechanism when removing olive oil, whereas emulsification (necking) and/or solubilization were observed in the removal of lard and tri-C₁₀. Only 20–25% of the olive oil remained after treatment with surfactants, which was much less compared to the solid fats where roughly 50% remained at end of treatment. The effect of adding lipases to the detergent formulation was clearly seen, both by an apparently higher rate of removal of olive oil but also using double injection when removing lard. A first injection of only surfactants removed a certain part of the lard as emulsion droplets stuck onto the fiber. A second injection of both lipases and surfactants was able to remove some of the preformed emulsion particles and reduce the overall remaining lard content on the cotton fiber.