Multi‐Component Self‐Assembly of Proteins and Inorganic Particles: From Discrete Structures to Biomimetic Materials

Due to their defined structure, proteins are suitable building blocks for the bottom‐up construction of multi‐component materials. Especially protein containers, with their inherent cavity, can be used to encapsulate synthetic components such as inorganic nanoparticles. This way, multi‐component discrete structures can be assembled. With recent advances in computational protein design, novel protein containers were successfully created, with a high potential for application in biomedicine and materials research. Moreover, engineered protein containers offer a unique building block for the self‐assembly of three‐dimensional materials. They combine the molecular precision of proteins with nanoscale dimensions. Designed interactions lead to novel protein scaffolds. In addition, nanoparticles encapsulated inside the container cavity introduce orthogonal functionality, important for the realization of nanostructured biomimetic materials with emergent properties.     

Highly active screen-printed IrTi4O7 anodes for proton exchange membrane electrolyzers

Electroceramic support materials can help reducing the noble-metal loading of iridium in the membrane electrodes assembly (MEA) of proton exchange membrane (PEM) electrolyzers. Highly active anodes containing Ir-black catalyst and submicronic Ti₄O₇ are manufactured through screen printing technique. Several vehicle solvents, including ethane-1,2-diol; propane-1,2-diol and cyclohexanol are investigated. Suitable functional anodic layer with iridium loading as low as 0.4 mg cm^?2 is obtained. Surface properties of the deposited layers are investigated by atomic force microscopy (AFM). The most homogeneous coating with the highest electronic conductivity is obtained using cyclohexanol. Tests in PEM electrolyzer operating at 1.7 V and 40 °C demonstrate that the CCM with anode coated with cyclohexanol presents a 1.5-fold higher Ir-mass activity than that of the commercial CCM.     

Synthesis and thermal behavior of [Li(thf)_3(μ-Cl)La{N(SiMe_3)_2}_3] and its investigation as spin-coating precursor for lanthanum-based layer formation

The lanthanum(Ⅲ) complex [Li(thf)_3(μ-CI)La{N(SiMe_3)_2}_3](3) was obtained by the reaction of LaCl_3 with three equiv of Li[N(SiMe_3)_2]_3 in a tetrahydrofuran solution. The molecular structure of 3 in the solid state was characterized by a tetracoordinated anionic lanthanide(Ⅲ) amide in form of an adduct with LiCl(thf)_3 as evidenced by single crystal X-ray structure analysis. In order to study the suitability of 3 as a precursor for the deposition of La_2O_3/LiLaSiO4 by thin layer deposition techniques,its thermal behavior was investigated by thermogravimetry(TG) and TG-MS-coupled studies. TG studies show a two-step decomposition process, whereby volatile decomposition products can be detected during the second decomposition step. TG measurements under an atmosphere of oxygen produced La_2O_3, Calcination processes of 3 under ambient atmosphere for 10 h at 1000 ℃ gave La_2O_3 and LiLaSiO_4,which was confirmed by PXRD studies. Metal-organic 3 was applied as spin-coating precursor for La_2O_3 thin film formation giving the as-deposited layers nearly crack-free.     

Tetranuclear yttrium and gadolinium 2-acetylcyclopentanoate clusters: Synthesis and their use as spin-coating precursors for metal oxide film formation for field-effect transistor fabrication

Lanthanide clusters [Ln_4(μ_3-OH)_2(η~2-accp)_4((μ-O)-η~2-accp)_6](Ln = Y(4),Gd(5); accp = 2-acetylcyclopentanoate) are accessible by treatment of [M(NO_3)_3·6 H_2 O](M = Y(1),Gd(2)) with 3 equiv. of Haccp(3) in presence of NaOH. The molecular structures of 4 and 5 in the solid-state are discussed. The thermal behavior of 4 and 5 was studied by TG under Ar and O_2, showing multistep decomposition processes. Additionally, DSC studies were carried out under an atmosphere of O_2. PXRD measurements of the TG residues confirm the formation of Ln_2 O_3.Spin-coating experiments were carried out with 4 and 5 for Ln_2 O_3 film deposition on silicon substrates. The layers are smooth, close and are of thicknesses of 18.87±1.13 nm and 25.59 ± 4.55 nm for Ln = Y and Gd, which was evidenced by SEM and EDX studies. Field-effect transistors were successfully fabricated by deposition of carbon nanotubes on top of the Y_2 O_3 films and formation of palladium contacts by a lift-off procedure. An on/off ratio of more than 4 orders of magnitude is achieved without considerable leakage currents. These results demonstrate the potential use of spin-coated Y_2 O_3 as a gate dielectric in electronic devices.     

Enhanced kinetics for the LiBH4:MgH2 multi-component hydrogen storage system – The effects of stoichiometry and decomposition environment on cycling behaviour

In situ neutron diffraction was undertaken on stoichiometric 2LiBD₄ : MgD₂ and non-stoichiometric 0.3LiBD₄:MgD₂ with both ratios decomposed under 1 bar deuterium and under dynamic vacuum. The subsequent cycling behaviour under 100 bar D₂ at 400 °C was investigated in situ. Analysis of the uptake through formation of deuterided products showed fast kinetics for the magnesium rich system, 0.3:1, with 90% deuteriding occurring within 10 min. This compares to only 60% deuteriding for the 2:1 sample after 4 h under similar conditions. These results demonstrate the strong influence of stoichiometry in the cycling kinetics compared to decomposition conditions, although the later determines the phase progression.     

Self-consistent algorithm for calibrating spectrometers to picometer accuracy over the entire wavelength range

Spectrometer calibration accuracies are of high importance for a wide range of applications. Typically, one calibrates the spectrometer with a calibration lamp, providing distinct and well-defined calibration lines. However, for small spectral ranges, where only two calibration lines are present, the calibration becomes inaccurate. We present a high-precision nonlinear wavelength calibration method, which is based on two or more reference lines from a calibration lamp. The additional key element introduced is a Fabry-Perot multilayer structure that yields multiple sharp transmission maxima of similar intensity over the full spectrometer range under broad-band illumination (e.g., white-light source). An iterative algorithm is put forward to obtain a self-consistent calibration of picometer precision over the full spectrometer range. In regions distant from calibration lines the accuracy is enhanced by at least a factor of two compared to conventional methods.     

Surface Reconstruction for free-space 360 degrees fluorescence molecular tomography and the effects of animal motion.

Complete projection (360 degrees ) free-space fluorescence tomography of opaque media is poised to enable 3-D imaging through entire small animals in vivo with improved depth resolution compared to 360 degrees -projection fiber-based systems or limited-view angle systems. This approach can lead to a new generation of Fluorescence Molecular Tomography (FMT) performance since it allows high spatial sampling of photon fields propagating through tissue at any projection, employing nonconstricted animal surfaces. Herein, we employ a volume carving method to capture 3-D surfaces of diffusive objects and register the captured surface in the geometry of an FMT 360 degrees -projection acquisition system to obtain 3-D fluorescence image reconstructions. Using experimental measurements we evaluate the accuracy of the surface capture procedure by reconstructing the surfaces of phantoms of known dimensions. We then employ this methodology to characterize the animal movement of anaesthetized animals. We find that the effects of animal movement on the FMT reconstructed image were within system resolution limits (approximately 0.07 cm).     

Rheinbrücke Breisach – Umbau und Instandsetzung einer 45 Jahre alten Stahlkonstruktion

The Rhine Bridge at Breisach – Alteration and maintenance work at a 45‐years‐old steel structure across the river Rhine. The Breisach Rhine Bridge between Breisach in Baden‐Württemberg, Germany, and Neuf‐Brisach in Alsace, France, is next to the Europe Bridge Kehl–Strasbourg the most important road connection between the two countries. The three‐pillar road bridge was built in 1962 using the foundation of an old railway bridge. The box girder of the bridge is welded as well as riveted and bolted. Both the design of the curb with its underseepage – a feature that was often used at that time but is now out of favour – and damages at the drain pipes in the girder box led to significant corrosion damage. In the future a bicycle lane will run over the bridge. For this an enlargement of the southern footpath is required. Bridge repair and maintenance work began in the spring of 2008. In this paper not only the details of the projects will be considered, but also the solutions to the problems discovered during repair work. An additional special feature of the bridge is the fact that two road construction agencies, one French, one German, are in charge of maintenance.     

In Vitro and In Vivo Inhibition of Intestinal Glucose Transport by Guava (Psidium Guajava) Extracts

1 Scope

Known pharmacological activities of guava (Psidium guajava) include modulation of blood glucose levels. However, mechanistic details remain unclear in many cases.

2 Methods and results

This study investigated the effects of different guava leaf and fruit extracts on intestinal glucose transport in vitro and on postprandial glucose levels in vivo. Substantial dose‐ and time‐dependent glucose transport inhibition (up to 80%) was observed for both guava fruit and leaf extracts, at conceivable physiological concentrations in Caco‐2 cells. Using sodium‐containing (both glucose transporters, sodium‐dependent glucose transporter 1 [SGLT1] and glucose transporter 2 [GLUT2], are active) and sodium‐free (only GLUT2 is active) conditions, we show that inhibition of GLUT2 was greater than that of SGLT1. Inhibitory properties of guava extracts also remained stable after digestive juice treatment, indicating a good chemical stability of the active substances. Furthermore, we could unequivocally show that guava extracts significantly reduced blood glucose levels (≈fourfold reduction) in a time‐dependent manner in vivo (C57BL/6N mice). Extracts were characterized with respect to their main putative bioactive compounds (polyphenols) using HPLC and LC‐MS.

3 Conclusion

The data demonstrated that guava leaf and fruit extracts can potentially contribute to the regulation of blood glucose levels.     

Organic solar cells incorporating buffer layers from indium doped zinc oxide nanoparticles

Monodisperse, indium doped zinc oxide (IZO) nanoparticles were prepared via the polyol-mediated synthesis and incorporated into regular and inverted poly-(3-hexylthiophene-2,5-diyl) and [6,6]-phenyl C₆₁-butyric acid methyl ester organic photovoltaic devices as buffer layers between the active layer and the cathode. Efficient hole blocking at the particle buffer layers leads to an enhanced open-circuit voltage of the solar cells. This effect is even more pronounced for inverted device architectures. Device degradation studies revealed a solar cell performance reduction upon sample exposition to ambient atmosphere. However, this degradation is fully reversible under UV illumination. In addition, the n-doped IZO particles form suitable charge carrier transport layers for an efficient recombination in an intermediate recombination zone in tandem solar cells. Accordingly we have fabricated fully solution-processed tandem solar cells and investigated their optoelectronic properties.