Research on sodium-ion batteries has recently been rediscovered and is currently mainly focused on finding suitable electrode materials that enable cell reactions of high energy densities combined with low cost. Naturally, an assessment of potential electrode materials requires a rational comparison with the analogue reaction in lithium-ion batteries. In this paper, we systematically discuss the broad range of different conversion reactions for sodium-ion batteries based on their basic thermodynamic properties and compare them with their lithium analogues. Capacities, voltages, energy densities and volume expansions are summarized to sketch out the scope for future studies in this research field. We show that for a given conversion electrode material, replacing lithium by sodium leads to a constant shift in cell potential ΔE°(Li-Na) depending on the material class. For chlorides ΔE°(Li-Na) equals nearly zero. The theoretical energy densities of conversion reactions of sodium with fluorides or chlorides as positive electrode materials typically reach values between 700 W h kg(-1) and 1000 W h kg(-1). Next to the thermodynamic assessment, results on several conversion reactions between copper compounds (CuS, CuO, CuCl, CuCl2) and sodium are being discussed. Reactions with CuS and CuO were chosen because these compounds are frequently studied for conversion reactions with lithium. Chlorides are interesting because of ΔE°(Li-Na)≈ 0 V. As a result of chloride solubility in the electrolyte, the conversion process proceeds at defined potentials under rather small kinetic limitations.

For both cells and tissues, shape is closely correlated with function presumably via geometry-dependent distribution of tension. In this study, we identify common shape determinants spanning cell and tissue scales. For cells whose sites of adhesion are restricted to small adhesive islands on a micropatterned substrate, shape resembles a sequence of inward-curved circular arcs. The same shape is observed for fibroblast-populated collagen gels that are pinned to a flat substrate. Quantitative image analysis reveals that, in both cases, arc radii increase with the spanning distance between the pinning points. Although the Laplace law for interfaces under tension predicts circular arcs, it cannot explain the observed dependence on the spanning distance. Computer simulations and theoretical modeling demonstrate that filamentous network mechanics and contractility give rise to a modified Laplace law that quantitatively explains our experimental findings on both cell and tissue scales. Our model in conjunction with actomyosin inhibition experiments further suggests that cell shape is regulated by two different control modes related to motor contractility and structural changes in the actin cytoskeleton.

Cell behavior is governed by interactions with the cellular environment. [1][2][3] These interactions include cell-cell as well as cell-extracellular matrix (ECM) contacts and act, in addition to soluble growth factors, as key regulators of cell survival, proliferation, and differentiation. However, not only the molecular composition of the contact sites, but also their spatial distributions impact cell behavior. [ 4 , 5 ] Realizing cell-culture scaffolds that mirror the complex in vivo arrangement of ECM components is an active area of biomaterials engineering. Corresponding 2D lithographically defi ned micropatterned structures are widely used and have even become commercially available. [6][7][8][9] In addition to patterned ligand distributions, mechanical interactions between cells and their environment also play an important role in regulating cellular functions. [ 10 ] Consequently, corresponding fl exible substrates were developed that allow measurements of cellular forces in 2D on planar substrates or pillar arrays. [ 11 , 12 ] However, discrepancies between cell behavior in vivo and in artifi cial 2D environments have become evident. [ 5 , 13 , 14 ] Therefore, devices that capture more of the structural complexity present in 3D tissues are highly desirable.Fibrous collagen or matrigel matrices are commonly used to study 3D cell behavior, [ 15 , 16 ] but these matrices have a random pore size and are structurally and chemically ill-defi ned. We [ 17 ] and others [18][19][20] have recently shown that direct laser writing (DLW) is a versatile technique to fabricate tailored 3D cell-culture scaffolds in the micrometer to nanometer range. By using an adequate photoresist, elastic 3D scaffolds for cell force measurements have also been realized. [ 17 ] These DLW scaffolds have been homogeneously coated with ECM molecules. Ideally, they should have an adjustable distribution of cell-substrate contact sites to manipulate cell adhesion and cell shape in all three dimensions. In this communication, we report on tailored 3D scaffolds with a controlled ECM distribution. By sequential DLW of two different photoresists, composite-polymer scaffolds with distinct protein-binding properties are fabricated and selectively biofunctionalized thereafter. We further demonstrate that cells cultured in these scaffolds selectively form cell adhesion sites with the functionalized parts, allowing for control of cell adhesion and cell shape in three dimensions, forming the basis for future designer tissue-culture scaffolds.To fabricate micrometer-scale composite-polymer scaffolds with distinct protein-binding properties as depicted in Figure 1 , we fi rst selected and characterized appropriate materials. For the small protein-binding cubes in the scaffolds we selected Ormocomp, a member of the inorganic (Si-O-Si)-organic hybrid polymer Ormocer family (Fraunhofer Institute for Silica Research, Würzburg, Germany). Ormocomp is a biocompatible photoresist that has previously been used in our lab to manufacture elastic 3D scaffolds...

The addition of poly(A) tails to RNA is a phenomenon common to all organisms examined so far. No homologues of the known polyadenylating enzymes are found in Archaea and little is known concerning the mechanisms of messenger RNA degradation in these organisms. Hyperthermophiles of the genus Sulfolobus contain a protein complex with high similarity to the exosome, which is known to degrade RNA in eukaryotes. Halophilic Archaea, however, do not encode homologues of these eukaryotic exosome components. In this work, we analysed RNA polyadenylation and degradation in the archaea Sulfolobus solfataricus and Haloferax volcanii. No RNA polyadenylation was detected in the halophilic archaeon H. volcanii. However, RNA polynucleotidylation occurred in hyperthermophiles of the genus Sulfolobus and was mediated by the archaea exosome complex. Together, our results identify the first organism without RNA polyadenylation and show a polyadenylation activity of the archaea exosome.

Elastic 3D scaffolds (see figure) are fabricated into a biocompatible photoresist using direct laser writing. These scaffolds can be rhythmically deformed by single beating cardiomyocytes and calibration with atomic force microscopy indicates that cellular forces down to 10–20 nN are detectable with the setup.