SupraCells: Living Mammalian Cells Protected within Functional Modular Nanoparticle‐Based Exoskeletons

Creating a synthetic exoskeleton from abiotic materials to protect delicate mammalian cells and impart them with new functionalities could revolutionize fields like cell‐based sensing and create diverse new cellular phenotypes. Herein, the concept of “SupraCells,” which are living mammalian cells encapsulated and protected within functional modular nanoparticle‐based exoskeletons, is introduced. Exoskeletons are generated within seconds through immediate interparticle and cell/particle complexation that abolishes the macropinocytotic and endocytotic nanoparticle internalization pathways that occur without complexation. SupraCell formation is shown to be generalizable to wide classes of nanoparticles and various types of cells. It induces a spore‐like state, wherein cells do not replicate or spread on surfaces but are endowed with extremophile properties, for example, resistance to osmotic stress, reactive oxygen species, pH, and UV exposure, along with abiotic properties like magnetism, conductivity, and multifluorescence. Upon decomplexation cells return to their normal replicative states. SupraCells represent a new class of living hybrid materials with a broad range of functionalities.     

Lateral Magnetically Modulated Multilayers by Combining Ion Implantation and Lithography

The combination of lithography and ion implantation is demonstrated to be a suitable method to prepare lateral multilayers. A laterally, compositionally, and magnetically modulated microscale pattern consisting of alternating Co (1.6 µm wide) and Co‐CoO (2.4 µm wide) lines has been obtained by oxygen ion implantation into a lithographically masked Au‐sandwiched Co thin film. Magnetoresistance along the lines (i.e., current and applied magnetic field are parallel to the lines) reveals an effective positive giant magnetoresistance (GMR) behavior at room temperature. Conversely, anisotropic magnetoresistance and GMR contributions are distinguished at low temperature (i.e., 10 K) since the O‐implanted areas become exchange coupled. This planar GMR is principally ascribed to the spatial modulation of coercivity in a spring‐magnet‐type configuration, which results in 180° Néel extrinsic domain walls at the Co/Co‐CoO interfaces. The versatility, in terms of pattern size, morphology, and composition adjustment, of this method offers a unique route to fabricate planar systems for, among others, spintronic research and applications.     

Estimating shear properties of walnut wood: a combined experimental and theoretical approach

In this study, several theoretical models to numerically estimate shear properties of orthotropic materials are introduced. These approaches are based on the combination of Hankinson’s empirically derived formula with other empirical and analytical calculations. Next to shear moduli, which are estimated from the elastic moduli and Poisson’s ratios, shear strengths are also estimated from the in-axis strengths. The models are validated by mechanical tests on walnut wood (Juglans regia L.), for which a sufficient data set can be found in literature. The Arcan test is used to estimate the shear moduli, while the shear block test is used to estimate the shear strengths. The results show that the model, which is based on a combined use of Hankinson’s formula and tensor rotation, gives the best estimation of shear moduli as evaluated by the minimum differences to the experimentally obtained results. For the shear strengths, a combination of Hankinson’s formula and Norris’ failure criterion shows the best agreement in comparison to the experimental data. The theoretical calculations may be used for a time efficient estimation of shear modulus and strength in comparison to the very time-consuming experimental estimation.     

Experiments of two pupil lateral motion tracking algorithms using a Shack–Hartmann sensor

Pupil stability is one of the factors which limit the performance and operational stability of adaptive optics (AO) systems. This paper analyses two pupil-tracking methods to measure the lateral pupil shift: the first one utilizes the fluxes in all outer edge sub-apertures of a Shack–Hartmann sensor and the second one utilizes the real-time interaction matrix used in an AO system. Experiments with 9?×?9 Shack–Hartmann sensor are conducted to verify both pupil-tracking algorithms. The results show that both algorithms are effective, after two correction steps, the residual pupil shift is reduced to less than 5% of a Shack–Hartmann sub-aperture.     

Un-jamming due to energetic instability: statics to dynamics

Granular Matter - A method to identify the parameters of rolling resistance between particles in the discrete element method is proposed in this paper. Experiments revealed that a free rolling...     

Nachgiebiger Elektrodenträger für Cochlea-Implantate mit fluidischer Aktuierung

The cochlear implant, consisting of a compliant electrode carrier (ET) and embedded electrodes with contact wires, is an auditory neuroprosthesis, which is surgically inserted into the inner ear (cochlea) in order to create an auditory impression in the hearing-impaired patients. For simplification of the insertion, a fluidically actuated electrode carrier with a changeable curvature is presented. The deformation of the ET is specifically manipulated by applying pressure to its interior and also by a non-stretchable thin fibre or stripe embedded in its wall. An analytical examination of scaling properties allows to use scaled structures for models and measurements. In order to determine the geometry of the ET, a model-based synthesis – FE method combined with analytical modelling – is carried out. The synthesis resulted in a conical shape of the ET with a cylindrical cavity closed at one end and a fiber running parallel to the cavity. Experimental studies on a measuring geometry show a maximum deviation of 0,6 bar at a maximum internal pressure of 6 bar. The investigations show that the proposed synthesis method is suitable for the development of surgical instruments with adjustable curvature.     

Quasi‐Continuous Wave Near‐Infrared Excitation of Upconversion Nanoparticles for Optogenetic Manipulation of C. elegans

Optogenetics is an emerging powerful tool to investigate workings of the nervous system. However, the use of low tissue penetrating visible light limits its therapeutic potential. Employing deep penetrating near‐infrared (NIR) light for optogenetics would be beneficial but it cannot be used directly. This issue can be tackled with upconversion nanoparticles (UCNs) acting as nanotransducers emitting at shorter wavelengths extending to the UV range upon NIR light excitation. Although attractive, implementation of such NIR‐optogenetics is hindered by the low UCN emission intensity that necessitates high NIR excitation intensities, resulting in overheating issues. A novel quasi‐continuous wave (quasi‐CW) excitation approach is developed that significantly enhances multiphoton emissions from UCNs, and for the first time NIR light‐triggered optogenetic manipulations are implemented in vitro and in C. elegans. The approach developed here enables the activation of channelrhodopsin‐2 with a significantly lower excitation power and UCN concentration along with negligible phototoxicity as seen with CW excitation, paving the way for therapeutic optogenetics.