Aalto University

About: Aalto University is a education organization based out in Espoo, Finland. It is known for research contribution in the topics: Computer science & Context (language use). The organization has 9969 authors who have published 32648 publications receiving 829626 citations. The organization is also known as: TKK & Aalto-korkeakoulu.

Interfacial engineering by proteins: exfoliation and functionalization of graphene by hydrophobins

Abstract: Graphene has attracted vast interest as a new material with many uses. 2] Two-dimensional, crystalline graphene has many advantageous properties, such as extremely high electric and thermal conductivity, high strength, and a large surface area. Many more useful properties can result from graphene assemblies and modification by different functionalities or additional molecules. One of the usual ways to functionalize graphene is chemical modification; however, attempts to modify the surface of graphene in a noncovalent, nondestructive way have also been successful. These methods typically involve the buildup of charge on the graphene surface to enable the stabilization and assembly of the graphene sheets on the basis of electrostatic interactions. In a further step towards more complex functionalities, we have now modified graphene with more specifically interacting coatings consisting of biomolecules. One of the main challenges in the production of graphene is the scalable, controllable, and safe processing and handling of individual graphene sheets. Methods for the fabrication of graphene in a dry environment include the micromechanical cleavage of graphene sheets from graphite and the epitaxial growth of graphene on certain substrates. 11] By these methods, very large entities of single-layer graphene can be produced, but the scalability and handling problems remain. High-yielding solution-based chemical methods that enable the handling of graphene in dispersed form have been proposed; however, they involve the direct oxidation of graphene, which may lower the conductivity of graphene dramatically. Recent reports on the exfoliation of graphene either in pure solvents or in the presence of surfactants offer promise for the production of graphene. The main benefits of solution methods are the better processability and increased safety of graphene when it is dispersed in a liquid instead of being used as a dry powder. The dispersion of graphene into aqueous solutions is especially attractive because of their nonvolatile nature. Herein, we present a method for the exfoliation and functionalization of graphene sheets by an amphiphilic protein. It is known that a microbial adhesion protein, HFBI (Figure 1a), which belongs to a class of proteins called hydrophobins, interacts strongly with hydrophobic surfaces, such as graphite and silicon. The protein has a strongly cross-linked fold containing four disulfide bridges. Its most striking feature is a patch of hydrophobic residues on one face of its structure. Thus, the protein resembles a typical surfactant with a hydrophilic and a hydrophobic part. In solution, hydrophobic interactions between individual proteins lead to the formation of dimers or tetramers. In the vicinity of the interface between water and air, however, assembly of the protein at the interface is strongly preferred, and the protein crystallizes as a 2D lattice. Lateral interactions between surface proteins at interfaces may lead

The temporal effects of relative and firm-level absorptive capacity on interorganizational learning

Abstract: We examine how determinants of absorptive capacity influence learning in alliances over time. Using longitudinal patent cross-citation data, we find an inverted U-shaped pattern over time that is influenced by firm-level and relational factors. Technological similarity only modestly increases learning in the initial stages of a relationship, but moderate levels substantially increase knowledge flows later in the alliance. High technological diversity is related to higher initial learning rates, but the effects diminish over time. Somewhat surprisingly, research and development intensity is negatively related to initial learning rates but has a considerable positive effect later in the relationship. We suggest that initial learning rates in alliances may be constrained by the capacity to absorb knowledge, while later-stage outcomes are constrained by exploitation capacity. Copyright © 2012 John Wiley & Sons, Ltd.

Patient‐specific reconstruction with 3D modeling and DMLS additive manufacturing

Abstract: Purpose – The purpose of this paper is to develop a workflow for 3D modeling and additive manufacturing (AM) of patient‐specific medical implants. The comprehensive workflow consists of four steps: medical imaging; 3D modelling; additive manufacturing; and clinical application. Implants are used to reconstruct bone damage or defects caused by trauma or disease. Traditionally, implants have been manually bent and shaped, either preoperatively or intraoperatively, with the help of anatomic solid models. The proposed workflow obviates the manual procedure and may result in more accurate and cost‐effective implants.Design/methodology/approach – A patient‐specific implant was digitally designed to reconstruct a facial bone defect. Several test pieces were additive manufactured from stainless steel and titanium by direct metal laser sintering (DMLS) technology. An additive manufactured titanium EOS Titanium Ti64 ELI reconstruction plate was successfully implanted onto the patient's injured orbital wall.Findings...

Nanocellulose: Recent Fundamental Advances and Emerging Biological and Biomimicking Applications.

Abstract: In the effort toward sustainable advanced functional materials, nanocelluloses have attracted extensive recent attention. Nanocelluloses range from rod-like highly crystalline cellulose nanocrystals to longer and more entangled cellulose nanofibers, earlier denoted also as microfibrillated celluloses and bacterial cellulose. In recent years, they have spurred research toward a wide range of applications, ranging from nanocomposites, viscosity modifiers, films, barrier layers, fibers, structural color, gels, aerogels and foams, and energy applications, until filtering membranes, to name a few. Still, nanocelluloses continue to show surprisingly high challenges to master their interactions and tailorability to allow well-controlled assemblies for functional materials. Rather than trying to review the already extensive nanocellulose literature at large, here selected aspects of the recent progress are the focus. Water interactions, which are central for processing for the functional properties, are discussed first. Then advanced hybrid gels toward (multi)stimuli responses, shape-memory materials, self-healing, adhesion and gluing, biological scaffolding, and forensic applications are discussed. Finally, composite fibers are discussed, as well as nanocellulose as a strategy for improvement of photosynthesis-based chemicals production. In summary, selected perspectives toward new directions for sustainable high-tech functional materials science based on nanocelluloses are described.