Transfer of molecular chirality to supramolecular chirality at nanoscale and microscale by chemical self-assembly has been studied intensively for years. However, how such molecular chirality further transfers to the macroscale along the same path remains elusive. Here we reveal how the chirality from molecular level transfers to macroscopic level via self-assembly. We assemble a macrostripe using enantiomeric camphorsulfonic acid (CSA)-doped polyaniline with hierarchical order. The stripe can twist into a single-handed helical ribbon via helical self-motion. A multi-scale chemo-mechanical model is used to elucidate the mechanism underlying its chirality transfer and induction. The molecular origin of this macroscopic helical chirality is verified. Results provide a comprehensive understanding of hierarchical chirality transfer and helical motion in self-assembled materials and even their natural analogues. The stripe exhibits disparate actuation behaviour under stimuli of enantiomeric amines and integrating such chiral perception with helical self-motion may motivate chiral biomimetic studies of smart materials.
Interlayer shear between graphene sheets plays an important role in graphene-based materials and devices, but the effect of in-plane deformation of graphene, which may depend on the graphene size, has not been fully understood. In this paper, the size effect on interlayer shear behavior between two graphene sheets is studied based on a non-linear shear-lag model with energy barrier analysis, in which both the lattice registry effect and the elastic deformation of graphene are taken into account, and molecular dynamics (MD) simulations are carried out to verify the model. Both theoretical prediction and MD simulations show that the maximum interlayer shear force of short graphene sheets increases with the graphene length and width. However, if the sheet length is beyond 20 nm, the maximum shear force cannot be further increased by increasing the graphene length due to the non-uniform relative displacement between graphene layers, which is caused by the in-plane deformation of graphene. The upper bound of the maximum shear force per unit graphene width is obtained analytically as a constant 5.6 N/m, suggesting that a small force can pull an infinite long graphene belt to slide on a graphene substrate. This study offers useful information for design and manufacture of graphene-based nano-devices and materials.
In this work, we have inspected the theoretical resistive switching properties of two ReRAM models based on heterojunction structures of Cu/SiO x nanoparticles (NPs)/Si and Si/SiO x NPs/Si, in which dielectric layers of the silica nanoparticles present dislocations at bicrystal interfaces. To validate the theoretical model, a charge storage device with the structure Cu/SiO x /Si was fabricated and its ReRAM properties were studied. Our examinations on the electrical, thermal and structural aspects of resistive switching uncovered the switching behavior relies upon the material properties and electrical characteristics of the switching layers, as well as the metal electrodes and the interfacial structure of grains within the dielectric materials. We also determined that the application of an external electric field at Grain Boundaries (GB) is crucial to resistive switching behavior. Moreover, we have demonstrated that the switching behavior is influenced by variations in the atomic structure and electronic properties, at the atomic length scale and picosecond timescale. Our findings furnish a useful reference for the future development and optimization of materials used in this technology.
A single-measurement sweep-free distributed Brillouin optical time domain analyzer (BOTDA) sensor based on phase detection is proposed and experimentally demonstrated employing digital optical frequency comb (DOFC) probe signal. Brillouin Phase Spectrum (BPS) of DOFC probe induced by Brillouin interaction is measured using coherent detection in a single acquisition, without any frequency scanning and data averaging. Single-measurement BOTDA sensor based on BPS in 10km long fiber is demonstrated with a response time of 100 μs, which is limited only by the fiber length. The spatial resolution is 51.2m, determined by the duration of DOFC. And the Brillouin frequency shift (BFS) uncertainty is estimated to be~1.5 MHz at the end of fiber under test (FUT). Benefiting from the fast response time, dynamic measurement up to 1 kHz vibration frequency has been demonstrated.
The selection of foreign-registered ships upon entering ports poses challenges to maritime authorities in ensuring the effectiveness of the port state control (PSC) inspection. The derived data from the ships' arrival notification system has been utilised in this study to identify the preferred vessel type for inspection. A combination of the Grey Relational Analysis (GRA) model and Entropy Weight Method (EWM) has been applied to discern the various types of ships that entered five selected ports in Malaysia and disclose the propensity of each vessel type. Based on 100,623 ship arrival records obtained for a period of five years (2015–2019), the types of ships were identified, analysed, scored, and graded. The result shows that the oil tanker has the highest value of grey relational grade for Bintulu port while the passenger ship is in the pole position for Penang port. Kuching port and Port Kelang share the container type as the first in the ranking, whereas Lahad Datu posted the oil tanker. Other results include the sequence of types at individual ports for providing useful information to help policymakers in establishing an effective inspection design. A similar approach is applicable in PSC inspection records for further analysis.
Abstract The physical reprogrammability of metamaterials provides unprecedented opportunities for tailoring changeable mechanical behaviors. It is envisioned that metamaterials can actively, precisely, and rapidly reprogram their performances through digital interfaces toward varying demands. However, on‐demand reprogramming by integration of physical and digital merits still remains less explored. Here, a real‐time reprogrammable mechanical metamaterial is reported that is guided by its own structure‐performance relations. The metamaterial consists of periodically tessellated bistable building blocks with built‐in soft actuators for state switching, exhibiting rich spatial heterogeneity. Guided by the pre‐established relations between state sequences and stress–strain curves, the metamaterial can accurately match a target curve by digitally tuning its state within 4 s. The metamaterial can be elastically tensioned and compressed under a strain of 4%, and its modulus tuning ratio reaches >30. Moreover, it also shows highly tunable shearing and bending performances. This work provides a new thought for the physical performance reprogrammability of artificial intelligent systems.
The poor gradation continuity of aeolian sand makes it difficult to control the degree of compaction of the roadbed. Using the relationship between the different moisture content of aeolian sand and the maximum dry density, the construction method of water sprinkling and water sinking method is adopted to carry out the construction. This paper studies the road backfill construction technology of aeolian sand abutment in the transition section of a culvert. To study the effect of the construction technology of aeolian sand abutment backfilling, the box culvert abutment backfilling area is divided into 6 areas. The compaction degree of the aeolian sand filling in each area was inspected on-site and the settlement observation was carried out. After 15 days, the compaction degree was above 96%, reaching the maximum settlement amount. The results show that the water consumption of the sprinkling roller compaction method is much smaller than that of the water sedimentation method, and the compaction effect and settlement effect are similar to that of the water sedimentation method. The process of static pressure once and vibratory pressure on the roller can meet the requirement of a degree of compaction greater than 96% has the best economic benefits.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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