The unique structural motifs and self-recognition properties of DNA can be exploited to generate self-assembling DNA nanostructures of specific shapes using a 'bottom-up' approach. Several assembly ...strategies have been developed for building complex three-dimensional (3D) DNA nanostructures. Recently, the DNA 'origami' method was used to build two-dimensional addressable DNA structures of arbitrary shape that can be used as platforms to arrange nanomaterials with high precision and specificity. A long-term goal of this field has been to construct fully addressable 3D DNA nanostructures. Here we extend the DNA origami method into three dimensions by creating an addressable DNA box 42 × 36 × 36 nm3 in size that can be opened in the presence of externally supplied DNA 'keys'. We thoroughly characterize the structure of this DNA box using cryogenic transmission electron microscopy, small-angle X-ray scattering and atomic force microscopy, and use fluorescence resonance energy transfer to optically monitor the opening of the lid. Controlled access to the interior compartment of this DNA nanocontainer could yield several interesting applications, for example as a logic sensor for multiple-sequence signals or for the controlled release of nanocargos.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A new photonic structure is produced from cellulose nanocrystal iridescent films reflecting both right and left circularly polarized light. Micrometer‐scale planar gaps perpendicular to the films' ...cross‐section between two different left‐handed films' cholesteric domains are impregnated with a nematic liquid crystal. This photonic feature is reversibly tuned by the application of an electric field or a temperature variation.
An understanding of how the amino acid sequence affects the interaction of peptides with lipid membranes remains mostly unknown. This type of knowledge is required to rationalize membrane-induced ...toxicity of amyloid peptides and to design peptides that can interact with lipid bilayers. Here, we perform a systematic study of how variations in the sequence of the amphipathic Ac-(FKFE)2-NH2 peptide affect its interaction with zwitterionic lipid bilayers using extensive all-atom molecular dynamics simulations in explicit solvent. Our results show that peptides with a net positive charge bind more frequently to the lipid bilayer than neutral or negatively charged sequences. Moreover, neutral amphipathic peptides made with the same numbers of phenylalanine (F), lysine (K), and glutamic (E) amino acids at different positions in the sequence differ significantly in their frequency of binding to the membrane. We find that peptides bind with a higher frequency to the membrane if their positive lysine side chains are more exposed to the solvent, which occurs if they are located at the extremity (as opposed to the middle) of the sequence. Non-polar residues play an important role in accounting for the adsorption of peptides onto the membrane. In particular, peptides made with less hydrophobic non-polar residues (e.g., valine and alanine) are significantly less adsorbed to the membrane compared to peptides made with phenylalanine. We also find that sequences where phenylalanine residues are located at the extremities of the peptide have a higher tendency to be adsorbed.
We study the stability of globular proteins as a function of temperature and pressure through NPT simulations of a coarse-grained model. We reproduce the elliptical stability of proteins and ...highlight a unifying microscopic mechanism for pressure and cold denaturations. The mechanism involves the solvation of nonpolar residues with a thin layer of water. These solvated states have lower volume and lower hydrogen-bond energy compared to other conformations of nonpolar solutes. Hence, these solvated states are favorable at high pressure and low temperature, and they facilitate protein unfolding under these thermodynamical conditions.
To provide insights into the stabilizing mechanisms of trimethylamine-N-oxide (TMAO) on protein structures, we perform all-atom molecular dynamics simulations of peptides and the Trp-cage ...miniprotein. The effects of TMAO on the backbone and charged residues of peptides are found to stabilize compact conformations, whereas effects of TMAO on nonpolar residues lead to peptide swelling. This suggests competing mechanisms of TMAO on proteins, which accounts for hydrophobic swelling, backbone collapse, and stabilization of charge-charge interactions. These mechanisms are observed in Trp cage.
The micellar state of Pluronic P123, which is a poly(ethylene oxide)-b-poly(propylene oxide)-b- poly(ethylene oxide) block polymer (EO20PO70EO20), has been investigated using SANS, SAXS, and ...differential scanning calorimetry under the conditions utilized in the synthesis of ordered mesoporous materials, such as SBA-15. The absolute intensity measurements, both with SANS and SAXS, have provided a detailed quantitative description of the P123 micelles in the framework of a simple core–shell spherical model. The model developed has been used to establish the structure of the copolymer micelles, including their size, shape, aggregation number and detailed composition, as well as the structural changes induced by varying reaction conditions. The effects of temperature, pH, acidic source and the addition of swelling agents (toluene and TMB) are reported and discussed.
Entrepreneurial action theory establishes that effective entrepreneurship requires daily action. Yet, empirical research on the daily antecedents of entrepreneurial action is relatively absent from ...the literature. We develop an entrepreneurial identity intervention and a theoretical model which integrates entrepreneurial identity theory with integrative self‐control theory (ISCT). We theorize that an entrepreneurial identity intervention administered in the morning will increase entrepreneurial action throughout the day. Further, we develop and test hypotheses regarding two mediating pathways, a motivation‐based pathway that relies on the felt passion of the entrepreneur and a control capacity‐based pathway that is connected to the entrepreneur's cognitive flexibility. We conducted two studies to validate the effectiveness of our intervention (Studies 1a and 1b) and four studies to test the validity and effectiveness of our experimental materials and measures (Studies A1a, A1b, A1c, and 2a). Our main study investigates the daily antecedents and mechanisms of entrepreneurial action using a within‐individual field experiment with 201 entrepreneurs (1458 daily observations). Overall, we find more within‐person than between‐person variance in entrepreneurial identity, daily action, and hypothesized meditators. We discuss the theoretical and practical implications of our findings for the entrepreneurship and organizational behavior literatures.
•Effects of sleep on leader-follower relationship development via hostility.•Leader’s lack of sleep influences follower’s relationship quality via hostility.•Follower’s lack of sleep influences ...leader’s relationship quality via hostility.•Sleep deprived individuals are not aware of the effects of sleep loss on others.
Drawing from the sleep and emotion regulation model, and attribution theory, we argue that sleep can influence the quality of the relationship between leaders and their followers. Specifically, we examined the effects of lack of sleep on leader-follower relationship development at the beginning of their dyad tenure. We hypothesized that the negative effects of lack of sleep on relationships are mediated by hostility. Results based on 86 new dyads (first three days of their work relationship) showed support for our hypotheses (Study 1). Results based on 40 leaders and 120 followers over three months (five waves) also showed that lack of sleep influences perceptions of relationship quality via hostility for both leaders and followers (Study 2). Moreover, we found that the direct effects of follower lack of sleep affect leader perceptions of relationship quality in the first month of their dyad tenure but decreasingly so over time; the direct effects of a leader lack of sleep on follower perceptions of relationship quality did not vary based on dyad tenure. Results revealed that individuals are not aware of the impact of their own lack of sleep on other people’s perceptions of relationship quality, suggesting that leaders and followers may be damaging their relationship without realizing it.
In this article, we theoretically develop and test the temporal intricacies of job engagement. Drawing on the attention view of social cognition, we examine the interplay of employees’ temporally ...relevant perspectives of fit (i.e., retrospected, current, and anticipated) within their ongoing membership to the organization. Utilizing field data gathered from a large multinational company over multiple time periods, we found support for a conditional indirect effect model. Specifically, our findings showed that current needs-supply (NS) fit accounted for two of the previously investigated antecedents of job engagement (i.e., psychological meaningfulness and safety), especially when organizational identification was low. Moreover, anticipated perceptions of NS fit fully mediated the influences of psychological meaningfulness and availability on job engagement. The mediating effect relating to psychological availability was also especially pronounced when organizational identification was low. By shedding light on employees’ temporally constructed psychological experiences, our research suggests that job engagement is not only affected by employees’ contemporaneous understandings of their jobs but also influenced by their perceptions of anticipated opportunities.
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