Self-folding nano- and micropatterned hydrogel tissue engineering scaffolds by single step photolithographic process

Current progress in tissue engineering is focused on the creation of environments in which cultures of relevant cells can adhere, grow and form functional tissue. We propose a method for controlled chemical and topographical cues through surface patterning of self-folding hydrogel films. This provides a conversion of 2D patterning techniques into a viable method of manufacturing a 3D scaffold. While similar bilayers have previously been demonstrated, here we present a faster and high throughput process for fabricating self-folding hydrogel devices incorporating controllable surface nanotopographies by serial hot embossing of sacrificial layers and photolithography

Increased efficiency of direct nanoimprinting on planar and curved bulk titanium through surface modification

In this work the direct transfer of nanopatterns into titanium is demonstrated. The nanofeatures are imprinted at room temperature using diamond stamps in a single step. We also show that the imprint properties of the titanium surface can be altered by anodisation yielding a significant reduction in the required imprint force for pattern transfer. The anodisation process is also utilised for curved titanium surfaces where a reduced imprint force is preferable to avoid sample deformation and damage. We finally demonstrate that our process can be applied directly to titanium rods

Method for calculating ice forces on structures A non-simultaneous failure model for dynamic ice structure interaction

SIGLEAvailable from TIB Hannover: F93B350 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Piecewise linear wavelet collocation on triangular grids, approximation of the boundary manifolds and quadrature

In this paper we consider a piecewise linear collocation method for the solution of a pseudo-differential equation of order r=0, -1 over a closed and smooth boundary manifold. The trial space is the space of all continuous and piecewise linear functions defined over a uniform triangular grid and the collocation points are the grid points. For the wavelet basis in the trial space we choose the three-point hierarchical basis together with a slight modification near the boundary points of the global patches of parametrization. We choose three, four, and six term linear combinations of Dirac delta functionals as wavelet basis in the space of test functionals. Though not all wavelets have vanishing moments, we derive the usual compression results, i.e. we prove that, for N degrees of freedom, the fully populated stiffness matrix of N"2 entries can be approximated by a sparse matrix with no more than O(N[log N]"2"."2"5) non-zero entries. The main topic of the present paper, however, is to show that the parametrization can be approximated by low order piecewise polynomial interpolation and that the integrals in the stiffness matrix can be computed by quadrature, where the quadrature rules are combinations of product integration applied to non analytic factors of the integrand and of high order Gauss rules applied to the analytic parts. The whole algorithm for the assembling of the matrix requires no more than O(N[log N]"4"."2"5) arithmetic operations, and the error of the collocation approximation, including the compression, the approximative parametrization, and the quadratures, is less than O(N"-"1[log N]"2). Note that, in contrast to wellknown algorithms by v.Petersdorff, Schwab, and Schneider, only a finite degree of smoothness is required. (orig.)Available from TIB Hannover: RR 5549(434)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Large volume nanoscale 3D printing: Nano-3DP

3D printers suffer from the inverse relationship between throughput and minimum feature size; with smaller features inducing a cubic increase in print time. Here we introduce Nano-3DP, a hybrid process that combines digital light projection 3D printing with nanoscale-relief patterning. The tool enables large volume (cm3) prints with nanoscale details at a truly rapid rate (~120 mm/hour). 40 nm features, half the size of the finest printed details to date, are produced across a scalable print volume. We address the intrinsic issues of throughput and pixel induced surface inhomogeneity. To demonstrate the unique potential realized by this printing method across different areas of science optical lenses, injection molding tools and bio-implants originally acquired by x-ray CT are produced with functional nanoscale surface details. Notably, in vitro bone cell analysis delivered a profound 4.5-fold increase in osteogenesis purely through the inclusion of nanoscale features on the printed surfaces