Electron-phonon coupling and localization of excitons in single silicon nanocrystals

We report a detailed photoluminescence (PL) study on single silicon nanocrystals produced by laser pyrolysis. The PL spectra reveal nearly homogeneously broadened zero-phonon lines coupled to Si-O-Si phonon transitions in the SiO2 shell. A systematic investigation of electron-phonon coupling is reported on the basis of single nanocrystals. The stepwise localization of electron and hole at the Si-SiO2 interface for nanocrystals smaller than d approximately 2.7 nm is driven by electron-phonon coupling. From the localization energies the effective Bohr radii of the (localized) electron and hole are estimated to be in the range of 1-2 bond lengths of Si-O and Si-Si.     

Biodegradable Elastic Sponge from Nanofibrous Biphasic Calcium Phosphate Ceramic as an Advanced Material for Regenerative Medicine

Biodegradable porous calcium phosphate (CaP) ceramics are widely used as synthetic graft substitutes for bone regeneration, owing to their chemical and structural similarity to bone and associated bioactivity in terms of bone-bonding, osteoconductive, and even osteoinductive properties. Nevertheless, the intrinsic brittleness and poor processability of porous CaP ceramics strongly impair their clinical applicability. Herein, a biphasic calcium phosphate (BCP) sponge is developed that consists of a self-supporting network of seamlessly interwoven hydroxyapatite nanowires and β-tricalcium phosphate nanofibers and possesses a highly interconnected porous structure with open cell geometry and ultrahigh porosity. Owing to its unique properties, the ceramic sponge can be easily processed into various shapes and dimensions, such as cylindrical scaffolds and thin, flexible membranes. Moreover, the BCP sponge can be introduced into a bone defect in a compacted or folded state from a syringe and, upon wetting, expand to its original shape, thereby filling the cavity. The nanofibrous sponge gradually degrades in vitro and rapidly mineralizes when immersed in simulated body fluid. Moreover, it adsorbs significantly more proteins than a conventional porous BCP ceramic. Finally, the nanofibrous sponge supports the attachment, proliferation, and osteogenic differentiation of human mesenchymal stromal cells comparable to the conventional porous BCP ceramic.     

Automated generation of physical surrogate vehicle models for crash optimization

International Journal of Mechanics and Materials in Design - A challenge in the design and optimization of vehicle structures is the high computational costs required for crash analysis. In this...     

Advancing integrated research on European river–sea systems: the DANUBIUS-RI project

ABSTRACT

Research at the interface between terrestrial, riverine, estuarine and marine environments is frequently constrained by significant disciplinary and geographical boundaries. This article outlines an international initiative, DANUBIUS-RI, which aims to address these problems by facilitating biogeochemical monitoring and interdisciplinary research on river–sea systems. The scope of the project spans the environmental, social and economic sciences and was accepted into the European Strategy Forum on Research Infrastructures roadmap in 2016. When operational, DANUBIUS-RI will offer researchers access to interdisciplinary expertise, facilities and European river–sea systems, providing a comprehensive platform for multidisciplinary research and training.     

State‐of‐the‐Art Analytical Methods for Assessing Dynamic Bonding Soft Matter Materials

Dynamic bonding materials are of high interest in a variety of fields in material science. The reversible nature of certain reaction classes is frequently employed for introducing key material properties such as the capability to self‐heal. In addition to the synthetic effort required for designing such materials, their analysis is a highly complex—yet important—endeavor. Herein, we critically review the current state of the art analytical methods and their application in the context of reversible bonding on demand soft matter material characterization for an in‐depth performance assessment. The main analytical focus lies on the characterization at the molecular level.     

Simulations of piezoelectric Lamb wave delay lines using a finite element method

The method of piezoelectric finite elements was applied to the simulation of piezoelectric Lamb-wave delay lines with and without acoustical absorbers. In this finite-element analysis, free as well as electrically driven vibrations were computed. The shapes of the symmetric Lamb modes were determined by the solution of eigenproblems, and the transient mechanical build-up process was studied for a switched electrical sine wave excitation. The transfer function, the group delay time, and the impedance matrix of devices of different designs are calculated. The good agreement between simulation and experimental results indicates the suitability of the finite-element method for optimizing acoustic delay-line devices.     

Challenges of Materials Technology for low Consumption Vehicle Concepts

The material strategy in the automobile industry is geared towards product features such as consumption reduction (lightweight design), performance gain in the powertrain, safety, improved comfort and enhanced driving pleasure, or towards new functions and effects achievable using materials, surfaces and layers. All of these features are required to meet the criteria of low‐cost and environmentally‐friendly producibility and resources recovery. Lightweight design has a key role to play in the development of vehicles with low consumption and emissions. Some examples and current trends are reviewed in this article.     

Effects of various fillers on the sliding wear of polymer composites

Short fibre reinforced polymer composites are nowadays used in numerous tribological applications. In spite of this fact, new developments are still under way to explore other fields of application for these materials and to tailor their properties for more extreme loading conditions. The references given at the end of this review describe some of these developments. In the present overview further approaches in designing polymeric composites in order to operate under low friction and low wear against steel counterparts are described. A particular emphasis is focused on special filler (including nanoparticle) reinforced thermoplastics and thermosets. Especially, the influence of particle size and filler contents on the wear performance is summarised. In some of the cases, an integration of traditional fillers with inorganic nanoparticles is introduced and presents an optimal effect. Furthermore, some new steps towards the development of functionally graded tribo-materials are illustrated.     

Knowledge environments representing molecular entities for the virtual physiological human

In essence, the virtual physiological human (VPH) is a multiscale representation of human physiology spanning from the molecular level via cellular processes and multicellular organization of tissues to complex organ function. The different scales of the VPH deal with different entities, relationships and processes, and in consequence the models used to describe and simulate biological functions vary significantly. Here, we describe methods and strategies to generate knowledge environments representing molecular entities that can be used for modelling the molecular scale of the VPH. Our strategy to generate knowledge environments representing molecular entities is based on the combination of information extraction from scientific text and the integration of information from biomolecular databases. We introduce @neuLink, a first prototype of an automatically generated, disease-specific knowledge environment combining biomolecular, chemical, genetic and medical information. Finally, we provide a perspective for the future implementation and use of knowledge environments representing molecular entities for the VPH.