Electrochemical synthesis of nanostructured ZnO films utilizing self-assembly of surfactant molecules at solid-liquid interfaces

An electrochemical synthesis strategy for the production of nanostructured films was developed by combining self-assembly of surfactant-inorganic aggregates at solid-liquid interfaces and an electrodeposition process. Through this approach high quality nanostructured ZnO films were cathodically deposited from a plating solution containing 0.1 wt % of sodium dodecyl sulfate (SDS). The resulting ZnO films possess lamellar structures with two different repeat distances, d001 = 31.7 A and d001* = 27.5 A, both of which feature well-defined long range order. Due to kinetically controlled surfactant-inorganic assembly during the deposition process, the film exhibits a wide distribution of the stacking directions of the ZnO layers, which will allow facile access of the guest molecules and analytes to the interlayers. The synthetic mechanism used here can be generalized to generate nanostructured films of other semiconducting and metallic materials with architectures that cannot be assembled by other means.     

Pore Development during the Carbonization Process of Lignin Microparticles Investigated by Small Angle X-ray Scattering

Application of low-cost carbon black from lignin highly depends on the materials properties, which might by determined by raw material and processing conditions. Four different technical lignins were subjected to thermostabilization followed by stepwise heat treatment up to a temperature of 2000 °C in order to obtain micro-sized carbon particles. The development of the pore structure, graphitization and inner surfaces were investigated by X-ray scattering complemented by scanning electron microscopy and FTIR spectroscopy. Lignosulfonate-based carbons exhibit a complex pore structure with nanopores and mesopores that evolve by heat treatment. Organosolv, kraft and soda lignin-based samples exhibit distinct pores growing steadily with heat treatment temperature. All carbons exhibit increasing pore size of about 0.5–2 nm and increasing inner surface, with a strong increase between 1200 °C and 1600 °C. The chemistry and bonding nature shifts from basic organic material towards pure graphite. The crystallite size was found to increase with the increasing degree of graphitization. Heat treatment of just 1600 °C might be sufficient for many applications, allowing to reduce production energy while maintaining materials properties.     

3D-shaping of biodegradable photopolymers for hard tissue replacement

Continuously increasing life expectancy results in a rising number of bone diseases and fractures. Replacements from natural sources are not only limited in their availability, they also have some serious disadvantages such as possible immunological reactions or transmission of diseases. New synthetic biodegradable materials based on photopolymers could be an alternative solution. In these investigations an acrylate-based monomer formulation has been developed, consisting of a biodegradable basis monomer which is derived from gelatin, different reactive diluents, an appropriate photoinitiator and filler materials. For the three-dimensional shaping process stereolithography is the method of choice because of its capability to produce cellular structures with high resolutions.     

The gravitomagnetic clock effect and its possible observation

The general relativistic gravitomagnetic clock effect involves a coupling between the orbital motion of a test particle and the rotation of the central mass and results in a difference in the proper periods of two counter–revolving satellites. It is shown that at ??(c^‐2) this effect has a simple analogue in the electromagnetic case. Moreover, in view of a possible measurement of the clock effect in the gravitational field of the Earth, we investigate the influence of some classical perturbing forces of the terrestrial space environment on the orbital motion of test bodies along opposite trajectories.     

Surgical anatomy of the larynx

Modern functionally oriented surgery of the larynx increasingly requires exact knowledge of the anatomy and landmarks of the endolaryngeal structures in relation to the laryngeal skeleton. Review of the literature reveals several opposing statements and controversial anatomical definitions regarding several clinically critical points. In order to obtain basic anatomical data morphological measurements were performed on a total of 50 laryngeal specimens. Measurements were taken on whole organs and on cuts in the horizontal and in the frontal plane, as well. The data were evaluated statistically, which resulted in the determination of average configurations and dimensions of cartilages and soft tissues of the larynx. In particular, the projection of the deeper structures on the surface and the distances and angles between the different structures were taken into consideration. In order to make these data clinically applicable a scale model has been developed that will allow a direct correlation and application for individual surgery.     

One‐ and two‐photon activity of cross‐conjugated photoinitiators with bathochromic shift

Intrigued by the good performance of 1,5‐diphenylpenta‐1,4‐diyn‐3‐one ( DPD ) as photoinitiator for radical polymerization we prepared and investigated several donor substituted derivatives. UV‐Vis spectroscopy revealed a gradual red‐shift of λ_max and higher extinction in the order of the donor capability. A methoxy‐substituted derivative ( O‐DPD ) exhibited significant photoinitiation activity in photo‐DSC experiments. Steady state photolysis experiments showed decreased decomposition rates with increasing donor capability. A dimethylamino derivative N‐DPD was even photostable under these conditions. Because of to the D‐π‐A‐π‐D system of these compounds two‐photon induced 3D photopolymerization experiments were performed and N‐DPD showed outstanding performance compared to often applied single photon initiators. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3280–3291, 2007     

Mechanical properties of spruce wood cell walls by nanoindentation

In order to study the effects of structural variability, nanoindentation experiments were performed in Norway spruce cell walls with highly variable cellulose microfibril angle and lignin content. Contrary to hardness, which showed no statistically significant relationship with changing microfibril angle and lignin content, the elastic modulus of the secondary cell wall decreased significantly with increasing microfibril angle. While the elastic moduli of cell walls with large microfibril angle agreed well with published values, the elastic moduli of cell walls with small microfibril angle were clearly underestimated in nanoindentation measurements. Hardness measurements in the cell corner middle lamella allowed us to estimate the yield stress of the cell-wall matrix to be 0.34±0.16 GPa. Since the hardness of the secondary cell wall was statistically not different from the hardness of the cell corner middle lamella, irrespective of high variability in cellulose microfibril angle, it is proposed that compressive yielding of wood-cell walls is a matrix-dominated process. PACS 83.80.Mc