Tissue morphogenesis and regeneration are essentially mechanical processes that involve coordination of cellular forces, production and structural remodeling of extracellular matrix (ECM), and cell migration. Discovering the principles of cell-ECM interactions and tissue-scale deformation in mechanically-loaded tissues is instrumental to the development of novel regenerative therapies. The combination of high-throughput three-dimensional (3D) culture systems and experimentally-validated computational models accelerate the study of these principles. https://www.selleckchem.com/products/FTY720.html In our previous work [E. Mailand, et al., Biophys. J., 2019, 117, 975-986], we showed that prominent surface stresses emerge in constrained fibroblast-populated collagen gels, driving the morphogenesis of fibrous microtissues. Here, we introduce an active material model that allows the embodiment of surface and bulk contractile stresses while maintaining the passive elasticity of the ECM in a 3D setting. Unlike existing models, the stresses are driven by mechanosensing and not by an externally applied signal. The mechanosensing component is incorporated in the model through a direct coupling of the local deformation state with the associated contractile force generation. Further, we propose a finite element implementation to account for large deformations, nonlinear active material response, and surface effects. Simulation results quantitatively capture complex shape changes during tissue formation and as a response to surgical disruption of tissue boundaries, allowing precise calibration of the parameters of the 3D model. The results of this study imply that the organization of the extracellular matrix in the bulk of the tissue may not be a major factor behind the morphogenesis of fibrous tissues at sub-millimeter length scales.Visible-light-induced asymmetric metallaphotoredox catalysis has become a powerful strategy in synthetic organic chemistry. IrIII/CuI dual asymmetric catalysis has been developed to achieve enantioselective decarboxylative cyanation. However, detailed mechanisms, such as catalytic cycles for dual catalysts and the role of a chiral ligand, remain obscure in these reactions. In this study, the catalytic cycle of this reaction is systematically investigated by DFT calculations to clarify the quenching mechanism of the photocatalyst and the origin of the excellent enantioselectivity. Interestingly, the radical mechanism merging oxidative quenching (IrIII-*IrIII-IrIV-IrIII) and copper catalytic cycles (CuI-CuII-CuIII-CuI) is favourable. It consists of five major processes single-electron oxidation of *IrIII by N-hydroxy-phthalimide (NHP) esters followed by decarboxylation to generate benzyl radical, oxidation of CuI by IrIVvia a single-electron transfer (SET) process, cyanide exchange, radical capture by CuII, and C-CN reductive elimination from CuIII. The cyanide exchange is the rate-determining step, whereas the C-CN reductive elimination is the enantio-determining step of the reaction. In addition, the origin of the high enantioselectivity was analyzed from the steric and electronic effects. This study will hopefully benefit the future understanding of such photoredox-mediated dual catalyzed asymmetric synthesis.Ferredoxin (Fd) is an electron carrier protein containing a [2Fe-2S] cluster. In this paper, we synthesized Se-Fd, in which four Cys residues coordinated to the cluster are substituted to selenocysteine. After the one-pot segment coupling by the thioester method, followed by deprotection and cluster loading, the desired Se-Fd was successfully obtained.Revealing the electronic structure of organic emitting molecules is instructive for tuning the electron-hole balance, one of the key factors in regulating the organic light emitting diode (OLED) performance. Herein, we introduced single molecule conductance measurement (SMCM) technology to probe the conductance of three-model emitting molecules on the Au surface, finding that their hole transporting ability across the metal-molecule interface can be suppressed after electron-withdrawing arms are connected to the center component. This observation would benefit the electron-hole balance of the film in large scale OLED devices whose holes are excessively relative to electrons. I-V modeling reveals that the conductance decrease between molecules is owing to the reduced metal-molecule coupling rather than the impaired energy level alignment. The electronic structure variation between molecules could also be revealed by photophysical measurement, electrochemical analysis, and density functional theory (DFT) simulations, which give supportive evidence of the SMCM result.The surprisingly rich chemistry of mechanically activated cleavage of disulfide bonds has been uncovered only recently. Using a disulfide protein mimic together with Cleland's reagent (DTT) as the attacking nucleophile in aqueous solution, our isotensional ab initio simulations add another surprise to the list. They unveil that noncovalent chalcogen-chalcogen 1,5-type SO interactions involving the S-S bridge and γ-carbonyl O are controlling the mechanochemical reactivity of disulfides at very low forces, thus adding a third reactivity regime to the hitherto known ones. In stark contrast to what is found in aqueous solution, no such chalcogen bonding arrangements are observed in the gas phase, which supports the conclusion that water plays a crucial role in stabilizing preferred conformations that support noncovalent SO bonds. These findings open the door to investigate chalcogen bonding in the realm of proteins using single-molecule force spectroscopy.Accurate models of the free energies of ions in solution are crucially important. They can be used to predict and understand the properties of electrolyte solutions in the huge number of important applications where these solutions play a central role such as electrochemical energy storage. The Born model, developed to describe ion solvation free energies, is widely considered to be critically flawed as it predicts a linear response of water to ionic charge, which fails to match water's supposed intrinsic preference to solvate anions over cations. Here, we demonstrate that the asymmetric response observed in simulation is the result of an arbitrary choice of the oxygen atom to be the centre of a water molecule. We show that an alternative and reasonable choice, which places the centre 0.5 Å towards the hydrogen atoms, results in a linear and charge symmetric response of water to ionic charge for a classical water model consistent with the Born model. Therefore, this asymmetry should be regarded as a property of the specific short-range repulsive interaction not an intrinsic electrostatic property of water and so the fact that the Born model does not reproduce it is not a limitation of this approach.