Continuous Shape Change Research Articles

Switching Chirality in Arrays of Shape-Reconfigurable Spindle Microparticles.

The giant circular photo-galvanic effect is realized in chiral metals when illuminated by circularly polarized light. However, the structure itself is not switchable nor is the crystal chirality in the adjacent chiral domains. Here spindle-shaped liquid crystalline elastomer microparticles that can switch from prolate to spherical to oblate reversibly upon heating above the nematic to isotropic transition temperature are synthesized. When arranged in a honeycomb lattice, the continuous shape change of the microparticles leads to lattice reconfiguration, from a right-handed chiral state to an achiral one, then to a left-handed chiral state, without breaking the translational symmetry. Accordingly, the sign of rotation of the polarized light passing through the lattices changes as measured by time-domain terahertz spectroscopy. Further, it can locally alter the chirality in the adjacent domains using near-infrared light illumination. The reconfigurable chiral microarrays will allow us to explore non-trivial symmetry-protected transport modes of topological lattices at the light-matter interface. Specifically, the ability to controllably create chiral states at the boundary of the achiral/chiral domains will lead to rich structures emerging from the interplay of symmetry and topology.

Fine-grained, nonlinear registration of live cell movies reveals spatiotemporal organization of diffuse molecular processes.

We present an application of nonlinear image registration to align in microscopy time lapse sequences for every frame the cell outline and interior with the outline and interior of the same cell in a reference frame. The registration relies on a subcellular fiducial marker, a cell motion mask, and a topological regularization that enforces diffeomorphism on the registration without significant loss of granularity. This allows spatiotemporal analysis of extremely noisy and diffuse molecular processes across the entire cell. We validate the registration method for different fiducial markers by measuring the intensity differences between predicted and original time lapse sequences of Actin cytoskeleton images and by uncovering zones of spatially organized GEF- and GTPase signaling dynamics visualized by FRET-based activity biosensors in MDA-MB-231 cells. We then demonstrate applications of the registration method in conjunction with stochastic time-series analysis. We describe distinct zones of locally coherent dynamics of the cytoplasmic protein Profilin in U2OS cells. Further analysis of the Profilin dynamics revealed strong relationships with Actin cytoskeleton reorganization during cell symmetry-breaking and polarization. This study thus provides a framework for extracting information to explore functional interactions between cell morphodynamics, protein distributions, and signaling in cells undergoing continuous shape changes. Matlab code implementing the proposed registration method is available at https://github.com/DanuserLab/Mask-Regularized-Diffeomorphic-Cell-Registration.

Java script animation of generator rotors under different modes of oscillation in two area four machine system

Computer technology advancements aid in the creation of instructional plans that allow students to study in a variety of ways. Animations and digital maps make it easier to understand abstract concepts and ensure that learning is permanent. Animation is a technique of creating continuous motion and shape change illusion. Interconnected power system often seems to be an intractably intricate morass of equations and ad hoc rules of thumb. Lack in visibility impedes learning about the power system phenomena. Animation can help us to convey information that would otherwise require a thousand or more words. This work is all about the development of a visualization tool in order to understand oscillatory dynamics of generator rotor. The power vs phase angle curve gradient interacting with generator rotor inertia forms an equivalent mass spring system. So, by this very reason different modes of oscillation in mass spring system are animated. A two area four machine system is modelled in MATLAB/Simulink by using Kron reduction technique and different modes of oscillation are analyzed. Later the animation of generator rotors of two area system are created with the help of HTML, Cascading Style Sheets (CSS) and Java Script. Each animation is coupled to the results obtained in MATLAB/Simulink under different modes of oscillation.

Use of shape memory alloy for active shock control bump application

A shape memory alloy (SMA) with composition of Ni50.1Ti49.9 (at. %) was used for fabrication of a 3-D bump structure intended for use as an active shock control bump (SCB) into a transonic wing. This kind of bump is a variable-geometry structure designed to reduce the drag induced by shock wave ensure wing’s aerodynamic performance over the entire range of operating conditions. To meet this target, the SMA bump requires to exhibit two-way shape memory effect (TWSME) so that it can yield continuous shape change by properly changing the driving temperature. Result from differential scanning calorimetry was first presented to provide material’s phase transformation temperatures. To obtain the TWSME, a thermo-mechanical training procedure was proposed and a set of training devices were designed for training SMA bump. The SMA bump in this paper is trained to have a relatively flat shape in high temperature and can swell up when cooling. After more than 80 times training, the TWSME of the material tends to be stable. Then the thermo-mechanical responses of the SMA bump which is subjected to about 100 times training was tested. The result shows that the trained SMA bump can generate about 1.2 mm maximum recoverable deformation during martensitic transformation, which is about 3% of the ratio of the deformation region. Finally, the influence of external load on the thermo-mechanical response of the trained SMA bump were also studied.

First- and second-order transformational apparent motion rely on common shape representations

When one figure is replaced with another that overlaps its spatial location, observers perceive an illusory, continuous shape change of the original object, a phenomenon known as transformational apparent motion (TAM). The current study investigated the extent to which TAM depends on a common, high-level shape representation that is independent of the shape-defining attribute. Specifically, we tested whether TAM is perceived similarly for both first- and second-order objects, defined by luminance and texture contrast, respectively. A compelling motion percept was observed in second-order TAM displays that was comparable to that seen in first-order TAM displays. Importantly, TAM for both stimulus classes showed the same pattern over a range of stimulus onset asynchronies. These results support the high-level shape account, indicating that TAM is driven by segmentation mechanisms that rely on high-level shape information rather than low-level visual characteristics.

Integrated optimization design of smart morphing wing for accurate shape control

Smart morphing wing, which is equipped with smart materials and able to change structural geometry adaptively, can further improve aerodynamic efficiency of aircraft. This paper presents a new integrated layout and topology optimization design for morphing wing driven by shape memory alloys (SMAs). By simultaneously optimizing the layout of smart actuators and topology of wing substrate, the ultimately determined configuration can achieve smooth, continuous and accurate geometric shape changes. In addition, aerodynamic analysis is carried out to compare smart morphing wing with traditional hinged airfoil. Finally, the optimized smart wing structure is constructed and tested to demonstrate and verify the morphing functionality. Application setbacks are also pointed out for further investigation.

Analyses of the plastic deformation of coated conductors deconstructed from ultra-high field test coils

REBCO coated conductors are now being used for building very high-field magnets with large electromagnetic stresses, both expected ones due to transport current × stresses and additional stresses resulting from the large screening currents inherent in wide tapes. Post mortem analyses of several recent test coils operated above 40 T show that significant conductor plastic deformation occurs, even for JBR stresses well below the ∼1 GPa yield of the Hastelloy substrate of the conductor. To investigate these deformation mechanisms, conductors were unwound after coil test and carefully examined with respect to their length-wise Ic which revealed many areas of local damage. Regions of interest were examined by metallographic cross-section, Hall microscopy, magneto-optic imaging and scanning electronic microscopy. Important damage frequently occurred to the outer edges of pancakes in the coil ends, which were often plastically deformed over the whole turn circumference, especially when this outer edge was a slit edge. Internal conductor damage was also seen, especially delamination between the buffer and REBCO layers at slit edges. Careful sectioning of the tape at ∼10 mm intervals showed that the plastic deformation of the turns was complex and variable around the turn circumference, with tape cross-sections that exhibited continuous shape change in the outer turns. The bending center line of tapes often shifted from the tape center line toward the edge closest to the coil center, indicating asymmetric effects of transport and screening current stresses across the conductor width. A surprising and vital result is that damage was prevalent when the slit edge was also the edge at which transport current flowed. This damage was absent when the transport current flowed at the not-slit edge, implying great sensitivity of the effect of screening current stresses to localized conductor damage.

Evolutionary Patterns of Mandible Shape Diversification of Caviomorph Rodents

Caviomorphs are a mainly South American rodent clade with high taxonomic and ecomorphological diversity. In this study, we combine geometric morphometric, functional, ancestral reconstruction, and macroevolutionary analyses to quantify the magnitude, direction, and rates of shape diversification of the caviomorph mandible, and to explore the morpho-functional implications and potential ecological catalysts of the observed shape changes. The mandible shape was significantly related to habits and size, and had a better fit with an evolutionary model where the main clades occupy distinct adaptive peaks. The morphological evolution of octodontoids is characterized by pulses of rate acceleration, but without reaching high disparity. Such pulses are mainly linked to the acquisition of fossorial specializations, including short and robust mandibles, and the increasement of forces at incisors. Conversely, derived cavioids show slower but continuous shape changes that allowed them to reach the most divergent, grazing morphologies in which slender mandibles with more marked antero-posterior movements for grinding action are favored. Interestingly, the major morphological changes occurred mainly during the early Oligocene and lower late Miocene, two time periods that involved global climatic events and strong changes in the vegetational structure of South America. The evolution of octodontoid and cavioid mandibles seems to be related to the occupation of subterranean and epigean niches, respectively, in the progressively expanded Cenozoic open landscapes of southern South America.

Research on atypical evolution characteristics of convex bank of typical bend in lower Jingjiang river under changing environment

Since Three Gorges Reservoir was put into operation, the water and sediment conditions have changed significantly, and the lower reach of the project have been adjusted to adapt to this change. The continuous bend of the Jingjiang section of the lower reach of the reservoir (Tiaoguan-Laijiapu) is selected as the research reach. The research methods of prototype data observation and physical model test were carried out, and the continuous erosion evolution and channel shape change characteristics of the reach are analyzed. The results show that the convex bank at the upper of the bend is eroded, the concave bank is deposited, the deep groove is moved to the right, widened and cut down, the deep groove at the lower of the bend is widened and brushed deep, the convex bank at the upper of the Laijiapu bend is scoured, the concave bank gradually deposited, and the deep groove of the whole bend is widened and deep scoured after Three Gorges Reservoir was built and used. The change of runoff conditions after the construction of the reservoir provide dynamic conditions for the continuous scouring of the convex bank. The main factors for the continuous erosion of the convex bank are the substantial reduction of sediment inflow downstream of the dam caused by reservoir sediment interception, sand mining and soil and water conservation. This study is universal and can provide reference for the research on evolution characteristics of the downstream bend reach of other large water conservancy projects.

Push-pull direct modeling of solid CAD models

Direct modeling is a very recent CAD modeling paradigm featuring direct, intuitive push-pull interactions with the geometry of the model to much increase model editing flexibility. The major issue for push-pull direct modeling is the possible inconsistency between the altered geometry of the model and its unchanged topology. The challenge of resolving the geometry-topology inconsistency lies in ensuring that the resulting model remains as a valid solid model and that the model shape follows a continuous change pattern. Although push-pull direct modeling has been implemented in several CAD software packages, robustness towards generating valid modeling results and continuous shape changes still remains an open issue. This paper proposes a systematic method to handle the resolution of any possible inconsistent situation. The method formulates the continuous shape change requirement as successive Boolean operations on the model volume, thereby guaranteeing valid solid models and continuous shape changes. Further, this formulation allows an easy implementation of push-pull direct modeling using existing CAD research and engineering results. In order to show the effectiveness of the proposed method, a software prototype is developed and the modeling results are compared with those of five leading CAD software packages.

Structured illumination microscopy with interleaved reconstruction (SIMILR).

Structured illumination microscopy (SIM) is the commonly used super-resolution (SR) technique for imaging subcellular dynamics. However, due to its need for multiple illumination patterns, the frame rate is just a fraction of that of conventional microscopy and is thus too slow for fast dynamic studies. A new SR image reconstruction method that maximizes the use of each subframe of the acquisition series is proposed for improving the super-resolved frame rate by N times for N illumination directions. The method requires no changes in raw data and is appropriate for many versions of SIM setup, including those implementing fast illumination pattern generation mechanism based on spatial light modulator or digital micromirror device. The performance of the proposed method is demonstrated through imaging the highly dynamic endoplasmic reticulum where continuous rapid growths or shape changes of tiny structures are observed.

A bioinspired reversible snapping hydrogel assembly

Typical hydrogels undergo slow and continuous shape change. Inspired by the Venus Flytrap, the current work presents a hydrogel assembly that can reversibly undergo a non-continuous rapid snapping shape change due to a bi-stable structure of the assembly. In particular, the reversible snapping change goes beyond the Venus Flytrap and is not known in the literature.

Multiple immunophenotypes of cardiac telocytes

AimsTelocytes (TCs) form a 3-dimensional network in the myocardial interstitium, which most probably play important role(s) in heart development. However, the dynamics of their prolongations, continuous cell shape changes and adherence properties have not been well documented till recently. The aim of this study was to investigate dynamics of extension of prolongations (Telopods) and multiple phenotypes of cardiac TCs cultured in vitro. MethodsCardiac TCs were isolated from neonatal rats by a combined enzyme digestion process and identified by light microscopy, immunofluorescence analysis and scanning using electron microscopy (SEM). Their continuous changes in shape were analyzed by a Live Cell Imaging System and multiple phenotypes were identified by immunofluorescence analysis using various markers, like vimentin, c-kit, CD34, nanog and sca-1. ResultsCardiac TCs displayed piriform/spindle/triangular shapes with long and slender telopodes showing extremely long prolongations. The morphology of cell body was continuously changing while their prolongations were extending gradually. After adhering to the surface, TCs’ movement and extension of their prolongations lasted for approximately 1.5h. Cardiac TCs expressed mesenchymal cell marker vimentin, hematopoietic stem cell marker CD34, embryonic stem cell-associated gene of Nanog, and myocardial stem cell markers sca-1 and c-kit. ConclusionThese findings indicate that cultured TCs in vitro have multiple phenotypes, which are most likely important for evaluating their functional roles in heart development.

Decreasing mitochondrial fission diminishes vascular smooth muscle cell migration and ameliorates intimal hyperplasia

Vascular smooth muscle cell (VSMC) migration in response to arterial wall injury is a critical process in the development of intimal hyperplasia. Cell migration is an energy-demanding process that is predicted to require mitochondrial function. Mitochondria are morphologically dynamic, undergoing continuous shape change through fission and fusion. However, the role of mitochondrial morphology in VSMC migration is not well understood. The aim of the study is to understand how mitochondrial fission contributes to VSMC migration and provides its in vivo relevance in the mouse model of intimal hyperplasia. In primary mouse VSMCs, the chemoattractant PDGF induced mitochondrial shortening through the mitochondrial fission protein dynamin-like protein 1 (DLP1)/Drp1. Perturbation of mitochondrial fission by expressing the dominant-negative mutant DLP1-K38A or by DLP1 silencing greatly decreased PDGF-induced lamellipodia formation and VSMC migration, indicating that mitochondrial fission is an important process in VSMC migration. PDGF induced an augmentation of mitochondrial energetics as well as ROS production, both of which were found to be necessary for VSMC migration. Mechanistically, the inhibition of mitochondrial fission induced an increase of mitochondrial inner membrane proton leak in VSMCs, abrogating the PDGF-induced energetic enhancement and an ROS increase. In an in vivo model of intimal hyperplasia, transgenic mice expressing DLP1-K38A displayed markedly reduced ROS levels and neointima formation in response to femoral artery wire injury. Mitochondrial fission is an integral process in cell migration, and controlling mitochondrial fission can limit VSMC migration and the pathological intimal hyperplasia by altering mitochondrial energetics and ROS levels.

Investigation of the shape change of bio-flocs and its influence on mass transport using particle image velocimetry.

In this laboratory study, an advanced flow visualization technique - particle image velocimetry (PIV) - was employed to investigate the change of shape of activated sludge flocs in water and its influence on the material transport characteristics of the flocs. The continuous shape change of the bio-flocs that occurred within a very short period of time could be captured by the PIV system. The results demonstrate that the fluid turbulence caused the shift of parts of a floc from one side to the other in less than 200 ms. During the continuous shape change, the liquid within the floc was forced out of the floc, which was then refilled with the liquid from the surrounding flow. For the bio-flocs saturated with a tracer dye, it was shown that the dye could be released from the flocs at a faster rate when the flocs were swayed around in water. The experimental results indicate that frequent shape change of bio-flocs facilitates the exchange of fluid and materials between the floc interior and the surrounding water. This mass transfer mechanism can be more important than molecular diffusion and internal permeation to the function and behavior of particle aggregates, including bio-flocs, in natural waters and treatment systems.

Predicting cell shapes in melanomas

Predicting cell shapes in melanomas

Transgenic Control of Mitochondrial Fission Induces Mitochondrial Uncoupling and Relieves Diabetic Oxidative Stress

Mitochondria are the essential eukaryotic organelles that produce most cellular energy. The energy production and supply by mitochondria appear closely associated with the continuous shape change of mitochondria mediated by fission and fusion, as evidenced not only by the hereditary diseases caused by mutations in fission/fusion genes but also by aberrant mitochondrial morphologies associated with numerous pathologic insults. However, how morphological change of mitochondria is linked to their energy-producing activity is poorly understood. In this study, we found that perturbation of mitochondrial fission induces a unique mitochondrial uncoupling phenomenon through a large-scale fluctuation of a mitochondrial inner membrane potential. Furthermore, by genetically controlling mitochondrial fission and thereby inducing mild proton leak in mice, we were able to relieve these mice from oxidative stress in a hyperglycemic model. These findings provide mechanistic insight into how mitochondrial fission participates in regulating mitochondrial activity. In addition, these results suggest a potential application of mitochondrial fission to control mitochondrial reactive oxygen species production and oxidative stress in many human diseases.

Morphology evolution route of PbS crystals via environment-friendly electrochemical deposition

We report the detailed roadmap of the morphology evolution of semiconductor PbS crystals synthesized by a green route. Without using any surfactant in our electrochemical deposition process, we obtained rich morphologies of PbS crystals in a bulk amount with uniform size, showing continuous shape change from octahedral to star-like, then to football-like, and finally to cubic morphology, by simple control over the PbCl2 precursor concentration. We discuss such a morphology evolution in detail on the basis of the relative contributions of branching growth and capping effects of the Cl− ions.

Influence of membrane surface shape change on the performance characteristics of a fiber optic microphone

At a reflective intensity modulated fiber optic microphone (RIM-FOM), the acoustic signal makes a membrane vibrate and modulate the reflected intensity. In the existing models of the RIM-FOM, the offset of all points of the membrane, due to the vibration, is assumed to be equal. However, this assumption does not represent the actual vibration of the membrane, which follows a continuous surface shape change caused by the acoustic signal. We establish a revised theoretical model in which the influence of the actual membrane surface shape change on the reflective intensity modulation is considered. Experiments show that there is a discrepancy between the experimental optimum operating distance and the analytical result from the existing model, while our new model gives a better agreement with the experimental results. In particular, our analysis shows that, in using the existing model, the other microphone performance characteristics are misestimated, while our revised model can provide a closer solution.

Mechanics and computational simulation of blood flow in microvessels

Blood is a concentrated suspension of red blood cells (RBCs). Motion and deformation of RBCs can be analyzed based on knowledge of their mechanical characteristics. Axisymmetric models for single-file motion of RBCs in capillaries yield predictions of apparent viscosity in good agreement with experimental results for diameters up to about 8 μm. Two-dimensional simulations, in which each RBC is represented as a set of interconnected viscoelastic elements, predict that off-centre RBCs in an 8-μm channel take asymmetric shapes and drift toward the centre-line. Predicted trajectories agree with observations in microvessels of the rat mesentery. An isolated RBC initially positioned near the wall of a 20-μm channel is deformed into an asymmetric shape, migrates away from the wall, and then enters a complex tumbling motion with continuous shape change. Realistic simulation of multiple interacting RBCs in microvessels remains as a major challenge.