Mixed Reality - Potential and Pitfalls for Representing History

Presentation (2019)

Exposome Boot Camp Keynote: Environmental Cheminformatics to Identify Unknown Chemicals and their Effects

Presentation (2019)

ChemInChIformatics: IUPAC's Role in the Environmental Monitoring Revolution

Scientific Conference (2019)

Der antike pyrrhonische Skeptizismus / Aus dem Deutschen ins Ukrainische übersetzt von Volodymyr Abaschnik

in Antike und Universitätsphilosophie. (2019)

NORMAN-SLE (Suspect List Exchange) Update for NORMAN GA in Milan, Nov 2019

Presentation (2019)

h- and p-adaptivity driven by recovery and residual-based error estimators for PHT-splines applied to time-harmonic acoustics

in Computers and Mathematics with Applications (2018), 77(9), 2369-2395

In this work, we demonstrate the application of PHT-splines for time-harmonic acoustic problems, modeled by the Helmholtz equation. Solutions of the Helmholtz equation have two features: global ... [more ▼]

In this work, we demonstrate the application of PHT-splines for time-harmonic acoustic problems, modeled by the Helmholtz equation. Solutions of the Helmholtz equation have two features: global oscillations associated with the wave number and local gradients caused by geometrical irregularities. We show that after a sufficient number of degrees of freedom is used to approximate global oscillations, adaptive refinement can capture local features of the solution. We compare residual-based and recovery-based error estimators and investigate the performance of -refinement. The simulations are done in the context of recently introduced Geometry Independent Field approximaTion (GIFT), where PHT-splines are only used to approximate the solution, while the computational domain is parameterized with NURBS. This approach builds on the natural adaptation ability of PHT-splines and avoids the re-parameterization of the NURBS geometry during the solution refinement process. [less ▲]

Predicting Ligand-Free Cell Attachment on Next-Generation Cellulose–Chitosan Hydrogels

in ACS Omega (2018), 3(1), 937--945

There is a growing appreciation that engineered biointerfaces can regulate cell behaviors, or functions. Most systems aim to mimic the cell-friendly extracellular matrix environment and incorporate ... [more ▼]

There is a growing appreciation that engineered biointerfaces can regulate cell behaviors, or functions. Most systems aim to mimic the cell-friendly extracellular matrix environment and incorporate protein ligands; however, the understanding of how a ligand-free system can achieve this is limited. Cell scaffold materials comprised of interfused chitosan–cellulose hydrogels promote cell attachment in ligand-free systems, and we demonstrate the role of cellulose molecular weight, MW, and chitosan content and MW in controlling material properties and thus regulating cell attachment. Semi-interpenetrating network (SIPN) gels, generated from cellulose/ionic liquid/cosolvent solutions, using chitosan solutions as phase inversion solvents, were stable and obviated the need for chemical coupling. Interface properties, including surface zeta-potential, dielectric constant, surface roughness, and shear modulus, were modified by varying the chitosan degree of polymerization and solution concentration, as well as the source of cellulose, creating a family of cellulose–chitosan SIPN materials. These features, in turn, affect cell attachment onto the hydrogels and the utility of this ligand-free approach is extended by forecasting cell attachment using regression modeling to isolate the effects of individual parameters in an initially complex system. We demonstrate that increasing the charge density, and/or shear modulus, of the hydrogel results in increased cell attachment. [less ▲]

Finding Small Molecules in Big Data - Analytica Munich

Scientific Conference (2018)

Modulating cell response on cellulose surfaces; tunable attachment and scaffold mechanics

in Cellulose (2017)

Combining surface chemical modification of cellulose to introduce positively charged trimethylammonium groups by reaction with glycidyltrimethylammonium chloride (GTMAC) allowed for direct attachment of ... [more ▼]

Combining surface chemical modification of cellulose to introduce positively charged trimethylammonium groups by reaction with glycidyltrimethylammonium chloride (GTMAC) allowed for direct attachment of mammalian MG-63 cells, without addition of protein modifiers, or ligands. Very small increases in the surface charge resulted in significant increases in cell attachment: at a degree of substitution (DS) of only 1.4\%, MG-63 cell attachment was \textgreater 90 compared to tissue culture plastic, whereas minimal attachment occurred on unmodified cellulose. Cell attachment plateaued above DS of ca. 1.85 reflecting a similar trend in surface charge, as determined from ζ-potential measurements and capacitance coupling (electric force microscopy). Cellulose film stiffness was modulated by cross linking with glyoxal (0.3–2.6 degree of crosslinking) to produce a range of materials with surface shear moduli from 76 to 448 kPa (measured using atomic force microscopy). Cell morphology on these materials could be regulated by tuning the stiffness of the scaffolds. Thus, we report tailored functionalised biomaterials based on cationic cellulose that can be tuned through surface reaction and glyoxal crosslinkin+g, to influence the attachment and morphology of cells. These scaffolds are the first steps towards materials designed to support cells and to regulate cell morphology on implanted biomaterials using only scaffold and cells, i.e. without added adhesion promoters. [less ▲]

Determination of High Frequency Dielectric Constant and Surface Potential of Graphene Oxide and Influence of Humidity by KPFM.

in Langmuir (2015)

We use Kelvin probe force microscopy (KPFM) and capacitance coupling (dC/dz) to study the electrical properties of graphene oxide (GO). We propose using the dC/dz signal to probe the high frequency ... [more ▼]

We use Kelvin probe force microscopy (KPFM) and capacitance coupling (dC/dz) to study the electrical properties of graphene oxide (GO). We propose using the dC/dz signal to probe the high frequency dielectric constant of mono- and few-layer GO. Our measurements suggest that the dynamic dielectric constant of GO is on the order of εGO ? 3.0 ε0, in the high frequency limit, and independent of the number of GO layers. The measurements are performed at a humidity controlled environment (5 of humidity). The effects of increasing humidity on both the dC/dz and KPFM measurements are analyzed. [less ▲]