Solvothermally Synthesized Sb₂Te₃ Platelets Show Unexpected Optical Contrasts in Mid-Infrared Near-Field Scanning Microscopy

We report nanoscale-resolved optical investigations on the local material properties of Sb₂Te₃ hexagonal platelets grown by solvothermal synthesis. Using mid-infrared near-field microscopy, we find a highly symmetric pattern, which is correlated to a growth spiral and which extends over the entire platelet. As the origin of the optical contrast, we identify domains with different densities of charge carriers. On Sb₂Te₃ samples grown by other means, we did not find a comparable domain structure

Covalent Cargo Loading to Molecular Shuttles via Copper-free “Click Chemistry”

An important prerequisite for molecular shuttle-based functional devices is the development of adequate linker chemistries to load and transport versatile cargoes. Copper-free “click chemistry” has not been applied before to covalently load cargo onto molecular shuttles propelled by biological motors such as kinesin. Due to the high biocompatibility and bioorthogonality of the strain-promoted azide-alkyne cycloaddition, this approach has pronounced advantages compared to previous methods

Simulating lateral distraction osteogenesis

<div><p>Distraction osteogenesis is an effective method for generating large amounts of bone <i>in situ</i> for treating pathologies such as large bone defects or skeletal malformations, for instance leg-length discrepancies. While an optimized distraction procedure might have the potential to reduce the rate of complications significantly, our knowledge of the underlying mechanobiological processes is still insufficient for systematic optimization of treatment parameters such as distraction rate or fixation stiffness. We present a novel numerical model of lateral distraction osteogenesis, based on a mechanically well-controlled <i>in vivo</i> experiment. This model extends an existing numerical model of callus healing with viscoplastic material properties for describing stress relaxation and stimuli history-dependent tissue differentiation, incorporating delay and memory effects. A reformulation of appositional growth based non-local biological stimuli in terms of spatial convolution as well as remeshing and solution-mapping procedures allow the model to cope with severe mesh distortions associated with large plastic deformations. With these enhancements, our model is capable of replicating the <i>in vivo</i> observations for lateral distraction osteogenesis in sheep using the same differentiation rules and the same set of parameters that successfully describes callus healing in sheep, indicating that tissue differentiation hypotheses originally developed for fracture healing scenarios might indeed be applicable to distraction as well. The response of the model to modified distraction parameters corresponds to existing studies, although the currently available data is insufficient for rigorous validation. As such, this study provides a first step towards developing models that can serve as tools for identifying both interesting research questions and, eventually, even optimizing clinical procedures once better data for calibration and validation becomes available.</p></div

Predicted bone concentration, vascularity and effective mechanical stimuli for the <i>in vivo</i> experiment by Claes et al. [32].

<p>The figure shows (from left to right) how the distribution of bone, vascularity and effective dilatational and distortional strain inside the healing area changes over time (from top to bottom). The legends beneath the columns explain the meaning of the color-coding for the corresponding column(s).</p

The model’s 2D geometry corresponds to a slice through one row of the drill holes [37].

<p>The model’s 2D geometry corresponds to a slice through one row of the drill holes [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0194500#pone.0194500.ref037" target="_blank">37</a>].</p

Overview of the simulation phases.

<p>The numerical model consists of seven distinct phases (left) that are explained in detail in the corresponding Methods sections (right).</p

Influence of time step size on predicted bone tissue distribution.

<p>Each column displays the evolution of bone tissue over time (rows, top to bottom) from blue (0% bone) to red (100% mineralized bone) for five different temporal discretizations (columns, left to right).</p

Literature data of numerous experiments, investigating the healing outcome under different fixation devices on osteotomies in long bone diaphyses of sheep.

<p>Literature data of numerous experiments, investigating the healing outcome under different fixation devices on osteotomies in long bone diaphyses of sheep.</p

Default parameter values.

<p>Default parameter values.</p

Viscoplastic material properties relative to the composite Young’s modulus <i>E</i>.

<p>Viscoplastic material properties relative to the composite Young’s modulus <i>E</i>.</p