Emergence of a smooth interface from growth of a dendritic network against a mechanosensitive contractile material

Structures and machines require smoothening of raw materials. Self-organized smoothening guides cell and tissue morphogenesis, and is relevant to advanced manufacturing. Across the syncytial Drosophila embryo surface, smooth interfaces form between expanding Arp2/3-based actin caps and surrounding actomyosin networks, demarcating the circumferences of nascent dome-like compartments used for pseudo-cleavage. We found that forming a smooth and circular boundary of the surrounding actomyosin domain requires Arp2/3 in vivo. To dissect the physical basis of this requirement, we reconstituted the interacting networks using node-based models. In simulations of actomyosin networks with local clearances in place of Arp2/3 domains, rough boundaries persisted when myosin contractility was low. With addition of expanding Arp2/3 network domains, myosin domain boundaries failed to smoothen, but accumulated myosin nodes and tension. After incorporating actomyosin mechanosensitivity, Arp2/3 network growth locally induced a surrounding contractile actomyosin ring that smoothened the interface between the cytoskeletal domains, an effect also evident in vivo. In this way, a smooth structure can emerge from the lateral interaction of irregular active materials.

Interface construction for charge transportation of ZnO/graphene multilayer films

In order to clarify the effect of interface construction on the charge transportation, the interfaces between zinc oxide (ZnO) and graphene layers were designed into the following types: the smooth interface by direct deposition ZnO layer onto the surface of fresh graphene/glass substrate; the nanoscale rough interface by Ar[Formula: see text] bombardment etching the surface of graphene/glass substrate before deposition of a ZnO layer, and rough ZnO/Ag/graphene interface by deposition Ag first and then ZnO layers on the rough graphene/glass substrate. The results showed that, compared to the morphology of the ZnO/graphene film with smooth surface, the particle sizes of the film with rough interface became fine and their shapes changed from sharp to round. The carriers’ mobility increased from 0.3 cm2 ⋅ V[Formula: see text] ⋅ s[Formula: see text] to 0.6 cm2 ⋅ V[Formula: see text] ⋅ s[Formula: see text] due to the enhancement of the nanocontact at the rough interface between ZnO and graphene layers. In order to improve the electrical properties of ZnO/graphene multilayer film, a 10 nm Ag layer was inserted into the rough graphene/glass and ZnO layer to construct the rough metal interface. The carrier concentration was enhanced from 10[Formula: see text] cm[Formula: see text] of ZnO/graphene to 10[Formula: see text] cm[Formula: see text] ZnO/Ag/graphene films, although the carrier mobility reduced slightly from ZnO/graphene 0.6 to ZnO/Ag/graphene 0.2 cm2 ⋅ V[Formula: see text] ⋅ s[Formula: see text]. The sheet resistance and resistivity of the ZnO/Ag/graphene multilayer film decreased dramatically by inserting the conductive Ag layer, which took the roles of both the provider of charge carriers from Ag layer and bridges of the carriers from graphene layer.

Seismic Behavior of Concrete-Filled Steel Tube (CFST) Column and Reinforced Concrete (RC) Beam Connections under Reversed Cyclic Loading

Previous studies on the connection between concrete-filled steel tube (CFST) columns and reinforced concrete (RC) beams have shown a loss of joint confinement because the steel tube was completely or partially cut in the joint area. This research presents a new connection system that provides joint confinement through a continuous steel tube. Potential sliding shear at the smooth interface between the columns and beams in the joint face is mitigated using two mechanisms: (i) shear connectors and (ii) longitudinal web beam reinforcement. This study tested two CFST column and RC beam joints to 4.5% drift ratio under combined compression axial load and lateral cyclic load. The experimental results revealed no cracks at the joint zone and the specimens satisfied the ACI 374.1-05 criteria, despite minor sliding at the beam-column interface. The finite element (FE) model showed good agreement with the experimental results.

Experimental Investigations on Interface between Ordinary and Lightweight Aggregate Concretes Cast at Different Times

Experimental investigations on 12 push-off specimens with dimensions of 600 × 300 × 180 mm (200 × 180 mm shear plane) were presented. Models reflected the connection between ordinary concrete (NWC) substrate and lightweight aggregate concrete (LWAC) overlay. The main purpose of the study was to investigate behaviour of the interface between concretes cast at different times. Two different interface conditions were considered: Smooth and rough (obtained by graining). In the selected elements, additional reinforcement consisting of one ∅8 bar was injected. The elements were tested under load control. The failure of the specimens without interface reinforcement was violent and resulted from breaking of the adhesive bond. Specimens with shear reinforcement failed in a ductile manner, however, due to the low reinforcement area, the residual load capacity was much lower than the load recorded just before cracking. It was found that mechanical roughening of the surface can lead to degradation of the concrete structure. As a result, the load-carrying capacities of elements with smooth interface proved to be higher than the ultimate loads of elements with deliberately roughened contacts. Comparative analysis showed that the existing design procedures ACI 318-19, Eurocode 2, Model Code 2010, and AASHTO can lead to safe but conservative estimation of the actual resistance of the concrete interface.

Emergence of a smooth interface from growth of a dendritic network against a mechanosensitive contractile material

Structures and machines require smoothening of raw materials. Self-organized smoothening guides cell and tissue morphogenesis, and is relevant to advanced manufacturing. Across the syncytial Drosophila embryo surface, smooth interfaces form between expanding Arp2/3-based actin caps and surrounding actomyosin networks, demarcating the circumferences of nascent dome-like compartments used for pseudo-cleavage. We found that smoothening of the actomyosin interfaces requires Arp2/3 in vivo. To dissect the physical basis of this requirement, we reconstituted the interacting networks using node-based models. When actomyosin networks were simulated with clearances instead of Arp2/3 networks, rough boundaries persisted with low levels of myosin contractility. With addition of expanding Arp2/3 networks, network-network interfaces failed to smoothen, but accumulated myosin nodes and tension. After incorporating actomyosin mechanosensitivity, Arp2/3 network growth induced local contractility and smoothening of the interfaces, effects also evident in vivo. In this way, a smooth structure can emerge from the lateral interaction of irregular starting materials.

Interaction between Precast Concrete Columns with Socket Foundations Using Different Bonding Interfaces

In this study, a novel test technique is used to experimentally study the behavior and performance of the socket joint used to stabilize the precast columns embedded in a foundation that is subject to lateral loading. The test program included the testing of five test specimens, which represent the condition of the prefabricated concrete columns, which are embedded in the foundation. five specimens were divided into two groups based on the embedded length. Group one consists of two samples with a smooth interface and different embedded lengths. Group two consists of three samples with constant embedding length, two of them with a smooth interface and the other with a rough interface. Self-compacting mortar (SCM) was used as the adhesive material to fill the gap between the concrete column and the base for the samples of the first group, while the non-shrinking mortar and the self-compacting mortar (SCM) were used as adhesive material. Fill the gap between the Concrete column and the base in the second group. The practical results showed the possibility to use the developed test method as an alternative test method for comparing and representing a relationship between the different cases of socket connections. It has also been found that the roughness of the interface increases the bearing capacity for the embedded length, which corresponds to and is less than the depth of the concrete column, otherwise it is not required.

Hydrodynamics of Two-Phase Gas-Very Viscous Liquid Flow in Heat Exchange Conditions

This paper presents the results of analyses of the impact of heat transfer conditions on the hydrodynamics of downward co-current annular flow in vertical tubes of very viscous liquid and gas. The research was conducted within the range of gas velocities of 0–30.0 m/s and liquid velocities of 0.001–0.254 m/s, while the viscosity was in the unprecedented range of 0.046–3.5 Pas. The research demonstrates that the volume and nature of the liquid waves with various amplitudes and frequencies arising on the surface of the film are relative to the flow rate and viscosity of the gas phase. At the same time, we found that, under the condition of liquid cooling, an increase in viscosity resulted in the formation of a smooth interface whereas, under the conditions where the liquid is heated at the end of the channel section, a greater number of capillary waves were formed. This research resulted in the development of new dependencies which take into account the influence of selected thermal and flow parameters (including mass fraction) on the values of volumes specific to very viscous liquid film flows. These dependencies improve the accuracy of calculation by 8–10% and are fully applicable to the description of the performance of an apparatus with a hydraulically generated liquid film.

Interplay of Topological States on TI/TCI Interfaces

Based on first-principles calculations, we study electronic structure of interfaces between a Z2 topological insulator (TI) SnBi2Te4 and a topological crystalline insulator (TCI) SnTe. We consider two interface models characterized by the different atomic structure on the contact of the SnTe(111) and SnBi2Te4(0001) slabs: the model when two materials are connected without intermixing (abrupt type of interface) and the interface model predicted to be realized at epitaxial immersion growth on topological insulator substrates (smooth interface). We find that a strong potential gradient at the abrupt interface leads to the redistribution of the topological states deeper from the interface plane which prevents the annihilation of the Γ¯ Dirac states, predicted earlier. In contrast, a smooth interface is characterized by minor charge transfer, which promotes the strong interplay between TI and TCI Γ¯ Dirac cones leading to their complete annihilation.The M¯ topologically protected Dirac state of SnTe(111) survives irrespective of the interface structure.