TY  - JOUR
A1  - Luxenhofer, Robert
A1  - Fetsch, Corinna
T1  - Thermal Properties of Aliphatic Polypeptoids
JF  - Polymers
N2  - A series of polypeptoid homopolymers bearing short (C1–C5) side chains of degrees of polymerization of 10–100 are studied with respect to thermal stability, glass transition and melting points. Thermogravimetric analysis of polypeptoids suggests stability to >200 °C. The study of the glass transition temperatures by differential scanning calorimetry revealed two dependencies. On the one hand an extension of the side chain by constant degree of polymerization decrease the glass transition temperatures (Tg) and on the other hand a raise of the degree of polymerization by constant side chain length leads to an increase of the Tg to a constant value. Melting points were observed for polypeptoids with a side chain comprising not less than three methyl carbon atoms. X-ray diffraction of polysarcosine and poly(N-ethylglycine) corroborates the observed lack of melting points and thus, their amorphous nature. Diffractograms of the other investigated polypeptoids imply that crystalline domains exist in the polymer powder.
KW  - peptoid
KW  - biomaterials
KW  - glass transition temperature
KW  - DSC
KW  - TGA
KW  - XRD
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96333
ER  - 
TY  - JOUR
A1  - Kollmannsberger, Philip
A1  - Kerschnitzki, Michael
A1  - Repp, Felix
A1  - Wagermaier, Wolfgang
A1  - Weinkamer, Richard
A1  - Fratzl, Peter
T1  - The small world of osteocytes: connectomics of the lacuno-canalicular network in bone
JF  - New Journal of Physics
N2  - Osteocytes and their cell processes reside in a large, interconnected network of voids pervading the mineralized bone matrix of most vertebrates. This osteocyte lacuno-canalicular network (OLCN) is believed to play important roles in mechanosensing, mineral homeostasis, and for the mechanical properties of bone. While the extracellular matrix structure of bone is extensively studied on ultrastructural and macroscopic scales, there is a lack of quantitative knowledge on how the cellular network is organized. Using a recently introduced imaging and quantification approach, we analyze the OLCN in different bone types from mouse and sheep that exhibit different degrees of structural organization not only of the cell network but also of the fibrous matrix deposited by the cells. We define a number of robust, quantitative measures that are derived from the theory of complex networks. These measures enable us to gain insights into how efficient the network is organized with regard to intercellular transport and communication. Our analysis shows that the cell network in regularly organized, slow-growing bone tissue from sheep is less connected, but more efficiently organized compared to irregular and fast-growing bone tissue from mice. On the level of statistical topological properties (edges per node, edge length and degree distribution), both network types are indistinguishable, highlighting that despite pronounced differences at the tissue level, the topological architecture of the osteocyte canalicular network at the subcellular level may be independent of species and bone type. Our results suggest a universal mechanism underlying the self-organization of individual cells into a large, interconnected network during bone formation and mineralization.
KW  - bone
KW  - osteocytes
KW  - networks
KW  - biomaterials
KW  - mechanobiology
KW  - image analysis
Y1  - 2017
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-170662
VL  - 19
IS  - 073019
ER  - 
TY  - JOUR
A1  - Liashenko, Ievgenii
A1  - Hrynevich, Andrei
A1  - Dalton, Paul D.
T1  - Designing Outside the Box: Unlocking the Geometric Freedom of Melt Electrowriting using Microscale Layer Shifting
JF  - Advanced Materials
N2  - Melt electrowriting, a high‐resolution additive manufacturing technology, has so far been developed with vertical stacking of fiber layers, with a printing trajectory that is constant for each layer. In this work, microscale layer shifting is introduced through deliberately offsetting the printing trajectory for each printed layer. Inaccuracies during the printing of sinusoidal walls are corrected via layer shifting, resulting in accurate control of their geometry and mechanical properties. Furthermore, more substantial layer shifting allows stacking of fiber layers in a horizontal manner, overcoming the electrostatic autofocusing effect that favors vertical layer stacking. Novel nonlinear geometries, such as overhangs, wall texturing and branching, and smooth and abrupt changes in printing trajectory are presented, demonstrating the flexibility of the layer shifting approach beyond the state‐of‐the‐art. The practice of microscale layer shifting for melt electrowriting enables more complex geometries that promise to have a profound impact on the development of products in a broad range of applications.
KW  - 3D printing
KW  - additive manufacturing
KW  - biomaterials
KW  - electrohydrodynamics
KW  - melt electrospinning writing
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-217974
VL  - 32
IS  - 28
ER  -