Heteromultivalency, which involves the simultaneous interactions of more than one type of ligand with more than one type of receptor, is ubiquitous in living systems and provides a powerful strategy ...to improve the binding efficiency of heterotopic species such as proteins and membranes. However, the design and development of artificial heteromultivalent receptors is still challenging owing to tedious synthesis processes and the need for precise control over the spatial arrangement of the binding sites. Here, we have designed a heteromultivalent platform by co-assembling cyclodextrin and calixarene amphiphiles, so that two orthogonal, non-covalent binding sites are distributed on the surface of the co-assembly. Binding with model peptides shows a synergistic effect of the two receptors, (hetero)multivalency and self-adaptability. The co-assembly shows promise for inhibition of the fibrillation of amyloid-β peptides and the dissolution of amyloid-β fibrils, substantially reducing amyloid cytotoxicity. This self-assembled heteromultivalency concept is easily amenable to other ensembles and targets, so that versatile biomedical applications can be envisaged.
The flow control devices (FCD) play an important role to realize the best metallurgical performance of the tundish. An integrated workflow for designing a single-strand tundish equipped with FCD is ...presented in this paper. Mean age theory was applied to predict the spatial mean age distributions in the tundish. Melt change efficiency (MCE) was used as a key measure to characterize the tundish’s mixing performance. Taguchi method was employed to optimize the design factors, i.e. geometrical parameters of the FCD. The fluid flow and mixing of materials were analyzed based on the numerical simulations of a developed computational fluid dynamics (CFD) model. Compared to the residence time distribution (RTD) method, the mean age theory shows advantages in both numerical accuracy and efficiency. In addition, the size and location of undesired mixing zones can be easily identified which is essential for tundish design. The developed workflow that combined the CFD-Taguchi method and mean age theory can be used as an efficient tool for wide industrial applications.
Surface passivation technology provides noble‐metal materials with limited chemical stability, especially under highly acidic condition. To design effective strategy to enhance stability of ...noble‐metal particles, an understanding of their surface anticorrosion mechanism at the atomic level is desirable by using two‐dimensional (2D) noble‐metal coordination polymer (CP) as an ideal model for their interfacial region. With the protection of 2‐thiobenzimidazole (TBI), we isolated two Ag‐based 2D CPs, {Ag14(TBI)12X2}n (S−X, where S denotes sheet and X=Cl or Br). These compounds exhibited excellent chemical stability upon immersion in various common solvents, boiling water, boiling ethanol, 10 % hydrogen peroxide, concentrated acid (12 M HCl), and concentrated alkali (19 M NaOH). Systematic characterization and DFT analyses demonstrate that the superior stability of S−X was attributed to the hydrophobic organic shell and dynamic proton buffer layer acting as a double protective “shield”.
Acid resistance (12 M HCl) was made possible for two isomorphic two‐dimensional silver‐based coordination polymers. Protection is provided by a hydrophobic organic shell and a dynamic proton buffer layer via a thiolate‐thione tautomerism of 2‐thiobenzimidazole ligands. Thus, these ligands are promising surface inhibitors, acting as a dual protective shield against metal corrosion.
Computational Fluid Dynamics (CFD) has become an indispensable tool that can potentially predict many phenomena of practical interest in the tundish. Model verification and validation (V&V) are ...essential parts of a CFD model development process if the models are to be used with sufficient confidence in real industrial tundish applications. The crucial aspects of CFD simulations in the tundish are addressed in this study, such as the selection of the turbulence models, meshing, boundary conditions, and selection of discretization schemes. A series of CFD benchmarking exercises are presented serving as selected examples of appropriate modelling strategies. A tundish database, initiated by German Steel Institute VDEH working group “Fluid Mechanics and Fluid Simulation”, was revisited with the aim of establishing a comprehensive set of best practice guidelines (BPG) in CFD simulations for tundish applications. These CFD benchmark exercises yield important results for the sensible application of CFD models and contribute to further improving the reliability of CFD applications in metallurgical reactors.
The mean age theory has recently been used to analyze the mixing efficiency in a single-strand tundish. The spatial distribution of the mean age was obtained by using a steady-state calculation. By ...applying the new theory of mean age, the computing cost was two orders of magnitude lower than when using the conventional theory of residence time distribution (RTD). This study aimed at extending the application of the mean age theory to a multi-strand tundish. Theoretical relations between the mean age and RTD were analyzed and compared for the tundish applications. A new criterion, the standard deviation of flow-weighted mean age at the multiple outlets, was applied focusing on the consistency of the flow in the multi-strand tundish. A five-strand tundish was selected as a benchmark case. The feasibility of applying the mean age theory in the multi-strand tundish was confirmed through the benchmarking results. Thus, the proposed method can be adopted as an effective tool in finding the optimal geometry of multi-strand tundish equipped with flow control devices (FCD).
Recognition of multifrequency microwave (MW) electric fields is challenging because of the complex interference of multifrequency fields in practical applications. Rydberg atom-based measurements for ...multifrequency MW electric fields is promising in MW radar and MW communications. However, Rydberg atoms are sensitive not only to the MW signal but also to noise from atomic collisions and the environment, meaning that solution of the governing Lindblad master equation of light-atom interactions is complicated by the inclusion of noise and high-order terms. Here, we solve these problems by combining Rydberg atoms with deep learning model, demonstrating that this model uses the sensitivity of the Rydberg atoms while also reducing the impact of noise without solving the master equation. As a proof-of-principle demonstration, the deep learning enhanced Rydberg receiver allows direct decoding of the frequency-division multiplexed signal. This type of sensing technology is expected to benefit Rydberg-based MW fields sensing and communication.
Natural convection of molten steel flow in a tundish occurs due to the temperature variation of the inlet stream and heat losses through top surface and refractory walls. A computational fluid ...dynamics (CFD) model was applied to study the effect of thermal buoyancy on fluid flow and residence-time distribution in a single-strand tundish. The CFD model was first validated with the experimental data from a non-isothermal water model and then applied to both scale-down model and prototype. The effects of flow control devices, including weir, dam and turbulence inhibitor, were compared and analyzed. Parameter studies of different heat losses through the top surface were performed. The results show that thermal buoyancy has a significant impact on the flow pattern and temperature distributions of molten steel in the tundish. The increase of heat loss through the top surface shortens the mean residence time of molten steel in the tundish, leading to an increase in dead volume fraction and a decrease in plug flow volume fraction.
Accurately distinguishing between enantiomeric molecules is a fundamental challenge in the field of chemistry. However, there is still significant room for improvement in both the enantiomeric ...selectivity (KR(S)/KS(R)) and binding strength of most reported macrocyclic chiral receptors to meet the demands of practical application scenarios. Herein, we synthesized a water‐soluble conjugated tubular host—namely, corral4BINOL—using a chiral 1,1′‐bi‐2‐naphthol (BINOL) derivative as the repeating unit. The conjugated chiral backbone endows corral4BINOL with good fluorescent emission (QY=34 % ) and circularly polarized luminescence (|glum| up to 1.4×10−3) in water. Notably, corral4BINOL exhibits high recognition affinity up to 8.6×1010 M−1 towards achiral guests in water, and manifested excellent enantioselectivity up to 18.7 towards chiral substrates, both of which represent the highest values observed among chiral macrocycles in aqueous solution. The ultrastrong binding strength, outstanding enantioselectivity, and facile accessibility, together with the superior fluorescent and chiroptical properties, endow corral4BINOL with great potential for a wide range of applications.
A pair of water‐soluble enantiomeric macrocycles was prepared using a chiral 1,1′‐bi‐2‐naphthol derivative as the building unit. The conjugated backbone results in the macrocycles having attractive chiral emissive properties, exceptional recognition affinity (up to 1010 M−1) and excellent enantioselectivity (up to 18.7) in water.
Abstract
Orbital eccentricity is one of the basic planetary properties, whose distribution may shed light on the history of planet formation and evolution. Here, in a series of works on Planetary ...Orbit Eccentricity Trends (dubbed POET), we study the distribution of planetary eccentricities and their dependence on stellar/planetary properties. In this paper, the first work of the POET series, we investigate whether and how the eccentricities of small planets depend on stellar metallicities (e.g., Fe/H). Previous studies on giant planets have found a significant correlation between planetary eccentricities and their host metallicities. Nevertheless, whether such a correlation exists for small planets (e.g., super-Earths and sub-Neptunes) remains unclear. Here, benefiting from the large and homogeneous LAMOST–Gaia–Kepler sample, we characterize the eccentricity distributions of 244 (286) small planets in single (multiple) transiting systems with the TDR method. We confirm the eccentricity–metallicity trend whereby the eccentricities of single small planets increase with stellar metallicities. Interestingly, a similar trend between eccentricity and metallicity is also found in the radial velocity sample. We also found that the mutual inclination of multiple transiting systems increases with metallicity, which predicts a moderate eccentricity–metallicity rising trend. Our results of the correlation between eccentricity (inclination) and metallicity for small planets support the core accretion model for planet formation, and they could be footprints of self (and/or external) excitation processes during the history of planet formation and evolution.
The existence of universal quantum computers has been theoretically well established. However, building up a real quantum computer system not only relies on the theory of universality, but also needs ...methods to satisfy requirements on other features, such as programmability, modularity, scalability, etc. To this end, here we study the recently proposed model of quantum von Neumann architecture by putting it in a practical and broader setting, namely, the hierarchical design of a computer system. We analyze the structures of quantum CPU and quantum control units and draw their connections with computational advantages. We also point out that a recent demonstration of our model would require less than 20 qubits.
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