Rapid Deformation Research Articles

Macrodeformation twinning in a textured aluminum alloy via dynamic equal channel angular pressing

Dynamic equal channel angular pressing experiments are conducted on an aluminum alloy with impact directions (ID) parallel to the rolling direction (RD), transverse direction (TD) and normal direction (ND), referred to as the ID $$\parallel $$ RD, ID $$\parallel $$ TD and ID $$\parallel $$ ND loading, respectively. Anisotropic deformation twinning is observed as a result of texture and grain elongation along RD, and the deformation twins can be activated both at grain boundaries and within grain interiors. Large-sized deformation twins (tens of $$\mu $$ m long) form in the ID $$\parallel $$ RD sample, while few twins are observed in the ID $$\parallel $$ TD and ID $$\parallel $$ ND samples during rapid severe plastic deformation. Molecular dynamics simulations are conducted to explain the effects of crystallographic orientations and grain geometry on deformation twinning. The resolved shear stress analysis shows that deformation twinning is easier to occur when the impact direction is along [001] and [110] than [111], and a larger grain dimension along the impact direction leads to a bigger twin size.

Role of structural parameters on strength-ductility combination of laminated carbon nanotubes/copper composites

Carbon nanotubes (CNTs) reinforced Cu laminated composites were constructed to analyze the effect of structural parameters on strength-ductility combination. CNTs were uniformly dispersed on Cu foils through electrophoresis deposition and embedded into the Cu matrix after hot pressing and rolling. Nanoscale CNTs/Cu composite layers were formed and a bimodal structure was induced. Introduction of CNTs and the induced laminated structure promote the enhancement in yield strength of ∼31 and ∼51 MPa in composites with original 100 and 30 μm Cu foils. More composite layers introduced by adopting 30 μm Cu foils inhibited the rapid concentrated plastic deformation and prolonged the crack pathway, thus realizing the strength-ductility combination. The deteriorated ductility of Cu layers in composite with original 100 μm Cu foils finally leaded to damaged ductility of the composite. This work provides a feasible way to construct the laminated composites and demonstrates the effect of structural parameters on strength-ductility combination.

Mapping ground movements caused by mining-induced earthquakes applying satellite radar interferometry

Anthropogenic activity related to the extraction of gas and oil, raw materials or water pumping leads to slow or rapid ground deformation. The ground motion rate is related to the type of the mined material, geological conditions, mining methods and other factors. Ground subsidence resulting from the collapse of underground post-mining voids occurs gradually. Mining-induced earthquakes and seismic earthquakes are largely unpredictable and have an adverse impact on the local inhabitants and buildings. For this reason, monitoring of this phenomenon is a challenge. The application of interferometric SAR for the evaluation of ground movement has brought satisfactory results over the past twenty years mainly in the regions where no other measurements were conducted during ground subsidence. In this paper we have examined a mining-induced earthquake with a magnitude 4.5 which occurred in an underground copper ore mine in Poland on 29th November 2016 and caused eight fatalities. It also had an impact on ground surface deformation in the vicinity of the mine tailings. An assessment of the earthquake-related impact on surface movement was carried out by Sentinel-1 TOPS time series interferometry. The velocity of ground movement and the scale of the phenomenon were investigated. In addition, the impact of the mining-induced earthquake on Zelazny Most mine tailings site was analyzed. Moreover, the process of dynamic ground compaction was also investigated in detail. Ground movement following the mine earthquake was explored. Two time phases of the movements were determined. The first phase of dynamic ground displacement was rapid and 90% of total ground deformation appeared on the surface within 7 days. The second phase of displacement was a ‘vanishing’ one; it lasted for approx. 3 weeks and 10% of ground deformation appeared on the surface. The study revealed that the maximum observed ground subsidence did not exceed 9 cm. The presented results contribute to a better understanding of post-earthquake ground deformations in the light of their spatial distribution in time.

A continuum theory for phase mixing and grain-damage relevant to tectonic plate boundary evolution

The unique occurrence of plate tectonics on Earth is rooted in the intricate physics of weakening and shear-localization in the cold ductile lithosphere. The pervasiveness of mylonites at lithospheric shear zones is a key piece of evidence that localization is correlated with reduction in mineral grain-size. The positive feedback leading to such localization, however, is often thought to be paradoxical because grain-size reduction by deformation-induced damage, and grain-size sensitive weakening do not necessarily co-exist in monomineralic materials. However, most lithospheric mylonites are polymineralic and the interaction between mineral phases, such as olivine and pyroxene, especially through Zener pinning, impedes normal grain growth while possibly enhancing grain-reduction via damage, even down to grain-sizes in which grain-size sensitive weakening is active. The efficacy of pinning, however, relies on the mineral phases being mixed and dispersed at the grain scale. Indeed, recent models and experiments imply that enhanced mixing between phases leads to greater grain-size reduction and weakening, whereas unmixed regions remain large-grained and strong. This duality of mixed states leads to a hysteresis effect, wherein slowly deforming states with large grains coexist with mylonitic-like states with rapid deformation, akin to the tectonic state of the Earth, with stiff plates coexisting with rapidly deforming plate boundaries. However, the different deformation states necessarily correspond to heterogeneity in mineral phase volume fractions, where the strong states correspond to monomineralic units of large-grained tectonites, while weaker mylonitic states occur in well-mixed polymineralic units. To model grain mixing between different phases at the continuum scale, we develop a new theory treating grain-scale processes as diffusion between phases, but driven by imposed stresses acting on the interface between phases. Simple one-dimensional (1-D) applications of the theory, and concomitant scaling laws show that diffusive grain mixing enhances grain-reduction by amplifying the influence of Zener pinning. The coupling between inter-phase diffusion and grain-damage promotes a positive mixing-localization feedback, which leads to narrow, weak, well-mixed polymineralic zones at the boundary between monomineralic units, as expected for bands of mylonites and ultramylonites. Flanking these narrow mixed zones are poorly mixed regions that have weaker pinning and grain-reduction, leading to large grains typical of tectonites and protomylonites. Thus, the continuum model for grain mixing and damage also predicts that weak, mylonitized plate boundaries can coexist with strong plate interiors for the same lithospheric temperature and driving stresses.

Mechanics of hard-magnetic soft materials

Soft materials that can undergo rapid and large deformation through the remote and wireless action of external stimuli offer a range of tantalizing applications such as soft robots, flexible electronics, and biomedical devices. A natural and simple embodiment of such materials is to embed magnetic particles in soft polymers. Unfortunately, existing magnetically responsive soft materials such as magnetorheological elastomers and ferrogels typically use magnetically-soft particles such as iron and iron oxides, which are characterized by the low coercivity and hence lack the capability to retain remnant magnetism. Accordingly, their deformation is limited to simple elongation or shortening, rendering these materials substantially unsuited for the complex transformations required in many applications. To introduce shape-programmability, magnetically-hard particles with high coercivity have been incorporated in mechanically soft materials. In addition, recent works aimed at ameliorating this situation have developed fabrication techniques and facile routes to engineer rapid and complex transformations in a programmable manner by introducing intricate patterns of magnetic polarities in soft materials. The resulting structures, when properly designed, have been shown to exhibit a diverse and rich array of actuation behavior. In this work, we develop a suitable theoretical framework to analyze these so-called hard-magnetic soft materials to facilitate the rational design of magnetically activated functional structures and devices based on a quantitative prediction of complex shape changes. We adopt a nonlinear field theory to describe the finite deformation coupled with magnetic fields and argue that the macroscopic behavior of the fabricated materials requires a new constitutive classification — ideal hard-magnetic soft material — which assumes that (i) the material has a residual magnetic flux density, and (ii) the induced magnetic flux density exhibits a linear relation with the applied actuating magnetic field. We implement the theory and constitutive law in a finite-element framework and find remarkable agreement between the simulation and experimental results on various deformation modes of hard-magnetic soft materials. Using the developed (and validated) model, we present a set of illustrative examples to highlight the use of our model-based simulation to guide the design of experimentally realizable complex shape-morphing structures based on hard-magnetic soft materials.

X-ray Investigation of Microstructure and Properties Evolution on Superalloy Inconel-718 derivative during Rapid Joule Heating and Severe Plastic Deformation Concurrently

The purpose of this study is to X-ray line-profile analysis of the effect of rapid Joule heating and severe plastic deformation concurrently on microstructure and properties evolution in polycrystalline austenitic Fe-balanced superalloy EP718E, which is Inconel 718 derivative. The microstructure of superalloy at different stages of processing was examined by X-ray diffraction, by scanning electron microscopy, and by energy dispersive spectrometry techniques. The mechanical properties of evolution were studied by means of tension and high cycle fatigue testings. The results of X-ray study show that the intensity, raw areas, and net areas were a step–by–step changed according to processing routines. Is shown that under shear stress the fcc-crystallites were deformed and the peaks parameters by 2-Theta scale changed partly.

Abstract A61: Engineered antigen presenting T cells for treatment of solid tumor cancers

Abstract Ex vivo manipulation of primary cells has shown immense clinical potential with the advent of adoptive T cell therapies to stimulate CD8 cytotoxic T lymphocyte (CTL) responses for the treatment of cancer. CTLs stimulated by tumor-associated antigens can target and clear solid tumors, however ex vivo manipulation methods for adoptive T cell transfer can be prohibitively time intensive. SQZ’s approach harnesses the endogenous T cell expansion mechanisms stimulated by antigen presentation to produce a relevant CTL dose. Previous efforts using antigen presenting cells (APCs) to induce this response have failed due to the difficulty inherent in delivering antigen to the APC cytosol, a necessary step for CTL activation. Within an APC, antigen location in the cytosol or endosome dictates how antigens are processed, presented, and the resultant adaptive immune system reaction. For an effective CTL response the antigens must be presented on MHC class I (MHC-I) molecules, which only occurs for antigens located in the cytosol. Antigen delivery methods, such as endocytosis, electroporation, and nanoparticle-based systems, can result in low efficiency, accumulation of material in endosomal compartments, cytotoxicity, and/or off-target effects. Furthermore, these processes are not amenable to scalable deployment, limiting the number of patients able to be treated. To circumvent such issues, we can achieve direct delivery of antigens into the APC cytosol with CellSqueeze®, resulting in MHC-I antigen presentation and effective stimulation of CTL activity. CellSqueeze® is a vector-free microfluidic platform that causes temporary membrane disruption by rapid mechanical deformation, enabling delivery of cell-engineering materials to diffuse into the cytosol without disrupting normal cell function. The CellSqueeze® platform, developed at MIT, has demonstrated efficacious delivery of various challenging materials, such as peptides and proteins, to patient-derived cells including stem cells and primary immune cells. We are developing our platform to employ primary human T cells as APCs. Previous CTL stimulation efforts have attempted to deliver antigenic material to dendritic cells (DCs); however, they are much less numerous in the blood and differentiation from monocytes is time consuming. This work uses primary human T cells, which are highly abundant in the blood, as APCs. We have demonstrated that delivery of antigenic material to T cells with the CellSqueeze® technology effectively enables the T cell to present the antigen to stimulate a targeted CTL response. In vitro we have demonstrated effective CTL activation using human T cells as APCs. In vivo we have demonstrated effective prophylactic and therapeutic treatment of murine tumors using CellSqueeze®-processed murine T cells in combination with multiple adjuvant strategies. We have also been investigating checkpoint inhibitors in combination with our T cell APCs. We believe that the unique ability to deliver molecules directly to the cytosol of T cells, as well as multiple other cell types, will enable a new paradigm in cellular therapy for multiple cancer types. Citation Format: LeeAnn Talarico, Ildefonso Vicente-Suarez, Katarina Blagovic, Eritza Chong-Ng, Lauren Jones, Lucas Pomerance, Howard Bernstein. Engineered antigen presenting T cells for treatment of solid tumor cancers [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2017 Oct 1-4; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2018;6(9 Suppl):Abstract nr A61.

Dynamic characteristics research of a ground fissure site at Xi’an, China

This paper studies the seismic response of an active ground fissure site subjected to earthquake by the shaking table model test. The settlement was induced by the earthquake in the ground fissure site. The settlement increased with the earthquake peak acceleration. The differential settlement has a third-order polynomial relationship with the earthquake intensity. The process of the settlement has three periods, including the rapid deformation stage, the stable deformation stage, and the accelerated development stage. The greatest settlement is in the hanging wall close to the fissure. The secondary fissures and new cracks developed and appeared during the earthquake. The high frequency component of the wave was reduced from the bottom to the top of the site and the low frequency component was amplified. The Fourier amplitude gradual increases correspond to the earthquake acceleration. The results discovery the relationship of subsidence, widen of fissure and the earthquake. It is contribute to the metro design of the fissure area.

Extremely early recurrence of intraplate fault rupture following the Tohoku-Oki earthquake

Intraplate earthquakes on a fault in Earth’s upper crust commonly recur in 1,000 years or longer. The 2011 M9 Tohoku-Oki earthquake triggered the activation of intraplate earthquakes in northern Kanto, Japan, including two M6 events on 19 March 2011 and 28 December 2016 located near one another. Here we use displacements captured by satellite radar and the Global Navigation Satellite System to show that the two earthquakes ruptured an identical fault. Detailed fault slip modelling shows that the deformation data for the two earthquakes are well explained by slip along a common fault geometry, and that the majority of the slipped area on the fault overlaps. Strain analysis reveals that the first M6 earthquake was followed by exceptionally large postseismic deformation. Such deformation is consistent with afterslip around the M6 rupture area, which in turn rebuilds the shear stress on the fault enabling the next earthquake. We infer that the rapid and large postseismic deformation of the 2011 Tohoku-Oki earthquake promoted such afterslip and made the second earthquake recur in just 5.8 years. This study suggests a mechanism to explain observations of extreme temporal clustering in palaeoseismic earthquake recurrence studies. A pair of closely spaced intraplate earthquakes in Japan can be explained by postseismic deformation associated with the 2011 Tohoku-Oki earthquake.

Modeling and Experimental Validation of Deformation of Al-33Cu Droplet during Impingement on a Substrate

Impingement of a molten Al-33Cu droplet over a substrate causes formation of a splat after spreading and solidification. Modeling of the heat transfer and fluid flow during the impingement and solidification of metal droplets on a substrate is helpful for the better understanding and control of related spray casting and thermal spray coating processes. Authors have thus developed a comprehensive mathematical model of the droplet impingement on the FLUENT 6.3.16 platform. The model takes into account all the inter-related phenomena, viz., (a) heat transfer through the droplet, solid substrate, solid-droplet interface and adjacent gaseous atmosphere, (b) fluid flow in the droplet and adjacent gas and (c) solidification. The droplet undergoes very large and rapid deformation during the impingement. The model predicts the deformation as well as the thermal and flow field within the droplet. Present work reports the experimental validation of model predictions on the droplet deformation, which was carried out using a high speed camera.

Application of Machine Learning to Classification of Volcanic Deformation in Routinely Generated InSAR Data

AbstractRecent improvements in the frequency, type, and availability of satellite images mean it is now feasible to routinely study volcanoes in remote and inaccessible regions, including those with no ground‐based monitoring. In particular, Interferometric Synthetic Aperture Radar data can detect surface deformation, which has a strong statistical link to eruption. However, the data set produced by the recently launched Sentinel‐1 satellite is too large to be manually analyzed on a global basis. In this study, we systematically process >30,000 short‐term interferograms at over 900 volcanoes and apply machine learning algorithms to automatically detect volcanic ground deformation. We use a convolutional neutral network to classify interferometric fringes in wrapped interferograms with no atmospheric corrections. We employ a transfer learning strategy and test a range of pretrained networks, finding that AlexNet is best suited to this task. The positive results are checked by an expert and fed back for model updating. Following training with a combination of both positive and negative examples, this method reduced the number of interferograms to ∼100 which required further inspection, of which at least 39 are considered true positives. We demonstrate that machine learning can efficiently detect large, rapid deformation signals in wrapped interferograms, but further development is required to detect slow or small deformation patterns which do not generate multiple fringes in short duration interferograms. This study is the first to use machine learning approaches for detecting volcanic deformation in large data sets and demonstrates the potential of such techniques for developing alert systems based on satellite imagery.

On the relation between ground surface deformation and seismicity during the 2012–2014 successive magmatic intrusions at El Hierro Island

Six different magmatic intrusions were detected around El Hierro Island in the two years that followed the end of the 2011–2012 submarine eruption. Each intrusion lasted between few days to three weeks and produced intense seismic swarms and rapid ground deformation. We performed a hypoDD relocation of >6000 earthquakes and inverted the GPS data in order to obtain the location of the magma source of each intrusion. Each episode presents a spatial gap between seismicity and magma source of 3–8 km with the earthquakes located always deeper than the deformation sources. We propose a magma plumbing system consisting on a deep structure injecting magma to a more ductile shallower location beneath El Hierro crust. While the seismicity is associated with the deeper structure, the ascent and accumulation of magma at shallower level deforms the crust aseismically. The mechanism of most of these episodes consists of an initial injection of magma producing most of the ground deformation and high b-values of the seismicity indicating fluid fractures during the first days and finishes with high magnitude earthquakes and low b-values indicating an overpressure of the injection process. There is a correlation between the seismic and geodetic moment ratio and the direction of propagation of each intrusion towards one of the volcanic rifts of the island, suggesting the possible existence of a deep structure beneath the island related with to the triaxial origin of the island. This work presents important advances in the knowledge of monogenetic magmatic intrusions and, specifically, in those occurred in El Hierro Island between 2011 and 2014, with important implications for future volcano monitoring in the Canary Islands.

Measurement Method of Deformation of Liquid Metal by Pulsed Electromagnetic Field

In order to verify that the non-uniform diameter of the metal jet can be deformed to a smaller diameter difference after the action of the electromagnetic field, a convenient and feasible test method is proposed. Mercury liquid metal was used as the test medium and a thermometer was used as the test equipment. A high-speed camera was used to record the deformation of the liquid metal, and the deformation of the liquid metal by the electromagnetic field was visually shown. The test results show that the liquid metal mercury is rapidly deformed by the electromagnetic field. The greater the magnetic induction intensity is, the stronger the deformation is. The greater the pulse discharge current is, the more obvious the mercury deformation is. The deformation measurement result conforms to the basic theory of the electromagnetic field. This method can be used to measure the electromagnetic field. The rapid deformation and flow under the effect provide a reference for the study of the deformation measurement of the electromagnetic enhanced armor technology and the electromagnetic constrained forming technology.

Microtopographic control on the ground thermal regime in ice wedge polygons

Abstract. The goal of this research is to constrain the influence of ice wedge polygon microtopography on near-surface ground temperatures. Ice wedge polygon microtopography is prone to rapid deformation in a changing climate, and cracking in the ice wedge depends on thermal conditions at the top of the permafrost; therefore, feedbacks between microtopography and ground temperature can shed light on the potential for future ice wedge cracking in the Arctic. We first report on a year of sub-daily ground temperature observations at 5 depths and 9 locations throughout a cluster of low-centered polygons near Prudhoe Bay, Alaska, and demonstrate that the rims become the coldest zone of the polygon during winter, due to thinner snowpack. We then calibrate a polygon-scale numerical model of coupled thermal and hydrologic processes against this dataset, achieving an RMSE of less than 1.1 ∘C between observed and simulated ground temperature. Finally, we conduct a sensitivity analysis of the model by systematically manipulating the height of the rims and the depth of the troughs and tracking the effects on ice wedge temperature. The results indicate that winter temperatures in the ice wedge are sensitive to both rim height and trough depth, but more sensitive to rim height. Rims act as preferential outlets of subsurface heat; increasing rim size decreases winter temperatures in the ice wedge. Deeper troughs lead to increased snow entrapment, promoting insulation of the ice wedge. The potential for ice wedge cracking is therefore reduced if rims are destroyed or if troughs subside, due to warmer conditions in the ice wedge. These findings can help explain the origins of secondary ice wedges in modern and ancient polygons. The findings also imply that the potential for re-establishing rims in modern thermokarst-affected terrain will be limited by reduced cracking activity in the ice wedges, even if regional air temperatures stabilize.

Analysis of the surface deformation characteristics and strata movement mechanism in the main shaft area of Chengchao Iron Mine

The surface deformation and strata movement caused by underground mining in a metal mine often exceeds the designed range, which can destroy main shafts and other key structures, causing huge economic losses and affecting production safety. Here, the main shaft area of Chengchao Iron Mine affected by tectonic stress is analyzed. Detailed monitoring data from the past 11 years were used to analyze the surface deformation characteristics and the strata movement mechanism. The results show that the surface deformation in the main shaft area shows S-shaped curve characteristics comprising a stable deformation stage, a rapid deformation stage and a stable deformation stage. The surface horizontal displacement vector in the main shaft area points to the western mining area, indicating that the surface deformation in the main shaft area is mainly affected by underground mining in the western area. From December 2007 to December 2009, the expansion of the movement line ( $$\varepsilon$$ = 2 mm/m) was small; in December 2009, the expansion of the movement line increased significantly. The expansion law of the break line ( $$\varepsilon$$ = 6 mm/m) was similar to that of the movement line. Furthermore, the movement angle decreased significantly from December 2009 to December 2011, and the break angle sharply decreased from December 2010 to December 2012. The cantilever beam mechanics model revealed that the fractured width of footwall in the direction of the main shaft area was 266 m. When exploitation reaches a horizontal depth of − 600 m, the fracture width is predicted to reach 402 m.

Stretchable Transparent Electrode Arrays for Simultaneous Electrical and Optical Interrogation of Neural Circuits in Vivo.

Recent developments of transparent electrode arrays provide a unique capability for simultaneous optical and electrical interrogation of neural circuits in the brain. However, none of these electrode arrays possess the stretchability highly desired for interfacing with mechanically active neural systems, such as the brain under injury, the spinal cord, and the peripheral nervous system (PNS). Here, we report a stretchable transparent electrode array from carbon nanotube (CNT) web-like thin films that retains excellent electrochemical performance and broad-band optical transparency under stretching and is highly durable under cyclic stretching deformation. We show that the CNT electrodes record well-defined neuronal response signals with negligible light-induced artifacts from cortical surfaces under optogenetic stimulation. Simultaneous two-photon calcium imaging through the transparent CNT electrodes from cortical surfaces of GCaMP-expressing mice with epilepsy shows individual activated neurons in brain regions from which the concurrent electrical recording is taken, thus providing complementary cellular information in addition to the high-temporal-resolution electrical recording. Notably, the studies on rats show that the CNT electrodes remain operational during and after brain contusion that involves the rapid deformation of both the electrode array and brain tissue. This enables real-time, continuous electrophysiological monitoring of cortical activity under traumatic brain injury. These results highlight the potential application of the stretchable transparent CNT electrode arrays in combining electrical and optical modalities to study neural circuits, especially under mechanically active conditions, which could potentially provide important new insights into the local circuit dynamics of the spinal cord and PNS as well as the mechanism underlying traumatic injuries of the nervous system.

Phreatic eruptions and deformation of Ioto Island (Iwo-jima), Japan, triggered by deep magma injection

On Ioto Island (Iwo-jima), 44 phreatic eruptions have been recorded since 1889, when people began to settle there. Four of these eruptions, after the beginning of continuous observation by seismometers in 1976, were accompanied by intense seismic activity and rapid crustal deformation beforehand. Other eruptions on Ioto were without obvious crustal activities. In this paper, we discuss the mechanisms of phreatic eruptions on Ioto. Regular geodetic surveys and continuous GNSS observations show that Ioto intermittently uplifts at an abnormally high rate. All of the four eruptions accompanied by the precursors took place during intermittent uplifts. The crustal deformation before and after one of these eruptions revealed that a sill-like deformation source in the shallow part of Motoyama rapidly inflated before and deflated after the beginning of the eruption. From the results of a seismic array and a borehole survey, it is estimated that there is a layer of lava at a depth of about 100–200 m, and there is a tuff layer about 200–500 m beneath it. The eruptions accompanied by the precursors probably occurred due to abrupt boiling of hot water in hydrothermal reservoirs in the tuff layer, sealed by the lava layer and triggered by intermittent uplift. For the eruptions without precursors, the hydrothermal systems are weakly sealed by clay or probably occurred on the same principle as a geyser because phreatic eruptions had occurred beforehand and hydrostatic pressure is applied to the hydrothermal reservoirs.

Dynamic ionic crosslinks enable high strength and ultrastretchability in a single elastomer

Maintenance-free self-healing elastomers that switch their mechanical properties on demand would be extremely useful materials for improving the functionalities, safety, energy efficiency, and lifetimes of many kinds of products and devices. However, strength and stretchability are conflicting properties for elastomers because the inherent crosslinking density of a polymeric network is unchangeable. For example, heavily crosslinked elastomers are strong, but poorly stretchable. Here we report an ionically crosslinked polyisoprene elastomer in which the ionic moieties are continually hopping between ionic aggregates at room temperature. Thus, the network is dynamic. This elastomer spontaneously self-heals without the input of external energy or healing agents. Furthermore, it behaves like a strong elastic material under rapid deformation, but acts like a highly stretchable and viscoelastic material under slow deformation. Our ionic elastomer shows a variety of notable mechanical properties, including high fracture strength (≈7 MPa), good toughness (≈70 MJ m−3), and ultrastretchability (>13,400%).

Prediction-based phase unwrapping for differential interferograms of coal mining areas using a stochastic medium model

ABSTRACTThis paper presents a novel phase unwrapping method for differential interferograms of coal mining areas, which takes full account of the mechanism of mining subsidence. The model uses a predicted deformation value for deformation caused by underground coal mining to assist the phase unwrapping and improve its accuracy. This method can overcome the defects of existing phase unwrapping algorithms that are not applicable to regions experiencing rapid deformation. The availability of the proposed method is first verified with noise-free simulated data, and then further tested with 3D laser scanning data and real synthetic aperture radar interferometry images. The results show that the prediction-based phase unwrapping method is able to realize phase unwrapping of differential interferograms covering coal mining areas that experience rapid deformation, and the results obtained are reasonable.

Pneumatic smart surfaces with rapidly switchable dominant and latent superhydrophobicity

Smart surfaces that possess switchable wettability are highly desired for a broad range of applications. However, the realization of novel approaches enabling complete alteration of surface properties independent of chemical environment and special materials is still challenging. Herein, inspired by the air sacs of insects, we fabricate a pneumatic smart surface that possesses dual-property wetting behavior and permits fast switching between states. The pneumatic surface is based on an embedded micro-air-sac network composed of an elastomer that was fabricated via a stretching-assisted mismatch-bonding process. By simply pumping the air sacs, the surface could undergo rapid and large-amplitude topography deformation, thereby exposing one surface and hiding the other, and the dominant surface and the latent surface could be switched reversibly. As a typical example, we demonstrate a smart surface with contrasting ‘petal’ and ‘lotus’ effects that enables the on-demand capture and release of water droplets. Our pneumatic strategy demonstrates a currently underexploited platform for the development of switchable smart surfaces.