Mechanism Of Shape Change Research Articles

ВІДНОВЛЕННЯ ПАЛАДІЄВИХ МЕМБРАН ПІСЛЯ КОНТАКТУ З ВОД-НЕМ ДЛЯ ВОДНЕВО-КИСНЕВИХ ПАЛИВНИХ ЕЛЕМЕНТІВ

Annotation. Studying the deformations of palladium membranes under the influence of hydrogen, which is a relevant issue for hydrogen energy and the nuclear industry. The mechanisms of palladium membrane shape change due to hydrogen penetration and the formation of temporary gradient alloys such as α-PdHn are consid-ered. Experiments were conducted using a hydrogen-vacuum installation, where the processes of membrane satu-ration and degassing were studied at temperatures from 100°C to 360°C and hydrogen pressures from 0.01 MPa to 2.5 MPa. It was established that the change in the shape of the membrane occurs in two stages: first, a rapid bending of the membrane is observed, and then a gradual return to the initial state. It was established that the maximum change in the shape of the membrane, which occurs at a constant temperature, depends on the diffu-sion coefficient and the equilibrium solubility of hydrogen in palladium. However, when the temperature chang-es, the diffusion coefficient of hydrogen in palladium and the equilibrium concentration of hydrogen in palladi-um also change, which affects the temperature dependence of the final shape change of the membrane. This fact makes it possible to effectively determine the time of hydrogen penetration into the membrane, control the change in shape and adjust the operating modes of the fuel cell. Special attention is paid to the use of palladium alloys with copper and silver to increase the resistance of membranes to the influence of hydrogen. It is shown that such alloys have better mechanical characteristics and a longer service life at high temperatures. The effect of degassing on the restoration of membranes after contact with hydrogen was studied, the main factors affecting the efficiency of this process were determined. The results of the work confirm the need for further research on increasing the resistance of palladium membranes to deformations, as well as the development of new materials and technologies to improve their operational characteristics

Model of Active Solids: Rigid Body Motion and Shape-Changing Mechanisms.

Active solids such as cell collectives, colloidal clusters, and active metamaterials exhibit diverse collective phenomena, ranging from rigid body motion to shape-changing mechanisms. The nonlinear dynamics of such active materials remains, however, poorly understood when they host zero-energy deformation modes and when noise is present. Here, we show that stress propagation in a model of active solids induces the spontaneous actuation of multiple soft floppy modes, even without exciting vibrational modes. By introducing an adiabatic approximation, we map the dynamics onto an effective Landau free energy, predicting mode selection and the onset of collective dynamics. These results open new ways to study and design living and robotic materials with multiple modes of locomotion and shape change.

Developing Shape Change-Based Fashion Prototyping Strategies: Enhancing Computational Thinking in Fashion Practice and Creativity

Emerging technologies enable fluid and versatile material forms of fashionable wearables and e-textiles, with experts in engineering and material science proposing numerous strategies for dynamic textile and garment structures to satisfy various needs. Nevertheless, a critical gap remains in developing practical fashion prototyping strategies that fuse with computational thinking to challenge current norms and envision the future of fashion. This study introduces shape change-based fashion prototyping as a design strategy for dynamic expressions and affordances to inspire fashion practitioners’ interdisciplinary endeavors. We present three studio-based practices as case studies to demonstrate how shape-changing mechanisms including servo motors, shape memory alloys, and pneumatics, spur new fashion construction skills and broaden the scope of potential applications. By doing so, this study contributes to material and conceptual innovation, creating pathways for the seamless integration of technologies from conceptualization, and implementation to envision. Our findings shed light on design possibilities and challenges and offer design recommendations that guide future endeavors. The implications of our research underscore the importance of adopting a relational approach to design variables, emphasize the value of fostering shared vocabulary between fashion and technical design, and highlight the transformative potential of shape-changing prototyping in reshaping the intricate body-material relationship.

Evaluation of coal mines’ rock mass gas permeability in the equivalent stress zone

Purpose. Based on a comparative analysis of the internal mechanism of shape change of rock samples, which were loaded in specified deformations mode, and geomechanical and gas-dynamic processes in coal mass, to establish a causal link between these phenomena. To qualitatively characterise their gas permeability as a function of the rock’s volume expansion. To justify the possibility of using a full “stress-strain” diagram as a technogenic methane deposit formation model and its spatial localisation. Methodology. Theoretical research is based on using the solid mechanic constitutive principles and results of studying the rock samples failure in the mode of specified strains. Findings. The ability to use a full “stress-strain” diagram for detecting and localising methane reservoirs during the coal seams excavation was proved during the research. It was found that the compaction threshold coincides with the bearing pressure maximum in front of the longwall face. This area corresponds to the rock mass with minimal porosity and minimal filtration, which allows considering it as an envelope of an artificial gas deposit. Regularities that connect the three-dimensional equivalent stress state with the final gas permeability of the gas-saturated coal mass were obtained. These data allow creating a predictive numerical geomechanical model of methane migration paths. Originality. The ability to use a full “stress-strain” diagram in the controlled strain mode for numerical modelling of gas permeability of a methane-saturated coal mass during the mining of coal seams and the determination of technogenic gas deposit boundaries are justified. Dependences of the current and final gas permeability on the rock’s mechanical characteristics in a post-peak strain state are obtained. Practical value. Functional dependencies based on geomechanical models are obtained that allow the identification and localisation of technogenic methane reservoirs in mines during coal seam excavation, with subsequent utilisation of the extracted gas. Furthermore, methane removal enhances mining safety by reducing the risk of gas dynamic phenomena while decreasing gas emissions into the atmosphere contributes to reducing the greenhouse effect.

Application of large-area electron beam irradiation to micro-edge filleting

Efficient micro-edge filleting with curvature radius from 10 to 100 μm for industrial products is required, since a demand for industrial components with precise and complex shape has been increasing recently. In large-area electron beam (EB) irradiation method, wide area of metal surface can be melted instantly and uniformly. Therefore, highly efficient surface finishing of metal can be performed. In addition, edge of convex part rounds since material removal and/or melting of the edge is preferentially done there due to difficulty of heat diffusion at the edge and concentration of EB. In this study, possibility of micro-edge filleting for workpiece with sharp edge by large-area EB irradiation was investigated. Experimental results show that micro-edge filleting without remarkable shape change of side surface near the edge can be performed under appropriate EB conditions. The curvature radius of edge can be controlled from sharp edge to rounded edge, and ideal curvature radius is obtained. Furthermore, thermo-fluid analysis with considering the concentration of EB to the edge was performed to clarify flow of molten metal and mechanism of edge shape change in the EB irradiation. Edge shape change can be simulated by the thermo-fluid analysis. It was made clear that surface tension is main driving force for edge shape change in large-area EB irradiation.

Extracting nanoscale membrane morphology from single-molecule localizations

Membrane surface reconstruction at the nanometer scale is required for understanding mechanisms of subcellular shape change. This historically has been the domain of electron microscopy, but extraction of surfaces from specific labels is a difficult task in this imaging modality. Existing methods for extracting surfaces from fluorescence microscopy have poor resolution or require high-quality super-resolution data that are manually cleaned and curated. Here, we present NanoWrap, a new method for extracting surfaces from generalized single-molecule localization microscopy data. This makes it possible to study the shape of specifically labeled membranous structures inside cells. We validate NanoWrap using simulations and demonstrate its reconstruction capabilities on single-molecule localization microscopy data of the endoplasmic reticulum and mitochondria. NanoWrap is implemented in the open-source Python Microscopy Environment.

Study on arc characteristics under high-frequency sine wave pulse current and effect of weld appearance and microstructure of AISI444 ferritic stainless steel

Based on the principle of LC resonance, high-frequency sine wave pulse DC TIG welding (HFSWP DC TIG) was developed, and welding experiments were conducted on AISI444 ferritic stainless steel (FSS). The arc characteristics of HFSWP DC TIG and its effect on weld appearance and microstructure were studied theoretically and experimentally. The experimental results show that under the same conditions, compared with constant-current DC conventional arc welding (CAW), the arc pressure and arc thermal efficiency of HFSWP DC TIG are improved, and the weld penetration of the weld is increased by nearly two times. The weld microstructure is single-phase ferrite, and carbonitride, Laves phase, and phase are formed in the joint. In addition, according to the theoretical calculation of the pulse current waveform, the reason why the arc pressure of the high-frequency sine wave pulse current is increased compared with the constant-current DC and high-frequency square wave (triangular wave) pulse current is explained. The mechanism of arc shape and weld appearance change is described from the microscopic point of view, and the reason for the appearance of equiaxed grain in the weld is analyzed. HFSWP DC TIG provides a new idea for the improvement of high-frequency pulse technology.

Design and Control of Magnetic Shape Memory Alloy Actuators.

This paper presents research on the application of magnetic shape memory alloys (MSMAs) in actuator design. MSMAs are a relatively new group of so-called smart materials that are distinguished by repeatable strains up to 6% and dynamics much better than that of thermally activated shape memory alloys (SMAs). The shape change mechanism in MSMAs is based on the rearrangement of martensite cells in the presence of an external magnetic field. In the first part of the article a review of the current state of MSMA actuator design is presented, followed by a description of the design, modelling and control of a newly proposed actuator. The developed actuator works with MSMA samples of 3 × 10 × 32 mm3, guaranteeing an available operating range of up to 1 mm, despite its great deformation range and dynamics. In the paper its dynamics model is proposed and its transfer function is derived. Moreover, the generalised Prandtl-Ishlinskii model of MSMA-actuator hysteresis is proposed. This model is then inverted and used in the control system for hysteresis compensation. A special test stand was designed and built to test the MSMA actuator with compensation. The step responses are recorded, showing that the compensated MSMA actuator exhibits the positioning accuracy as ±2 µm. As a result, the authors decided to apply a control system based on an inverse hysteresis model. The paper concludes with a summary of the research results, with theoretical analysis compared with the registered actuator characteristics.

Light activation of 3D-printed structures: from millimeter to sub-micrometer scale.

Three-dimensional (3D) printing enables the fabrication of complex, highly customizable structures, which are difficult to fabricate using conventional fabrication methods. Recently, the concept of four-dimensional (4D) printing has emerged, which adds active and responsive functions to 3D-printed structures. Deployable or adaptive structures with desired structural and functional changes can be fabricated using 4D printing; thus, 4D printing can be applied to actuators, soft robots, sensors, medical devices, and active and reconfigurable photonic devices. The shape of 3D-printed structures can be transformed in response to external stimuli, such as heat, light, electric and magnetic fields, and humidity. Light has unique advantages as a stimulus for active devices because it can remotely and selectively induce structural changes. There have been studies on the light activation of nanomaterial composites, but they were limited to rather simple planar structures. Recently, the light activation of 3D-printed complex structures has attracted increasing attention. However, there has been no comprehensive review of this emerging topic yet. Inthis paper, we present a comprehensive review of the lightactivation of 3D-printed structures. First, we introduce representative smart materials and general shape-changing mechanisms in 4D printing. Then, we focus on the design and recent demonstration of remote light activation, particularly detailing photothermal activations based on nanomaterial composites. We explain the light activation of 3D-printed structures from the millimeter to sub-micrometer scale.

The microstructure evolution history and the underlying mechanism of an α/β dual phase titanium alloy during elastic-plastic deformation process

In this paper, in situ scanning electron microscope tensile test was carried out on the Ti-4.5Mo-5.1Al-1.8Zr-1.1Sn-2.5Cr-2.9Zn alloy, and the mechanism of grain rotation, shape change and micro-strain redistribution in macroscopic elastic deformation (stage I), macroscopic elastic-plastic transition (stage II) and macroscopic plastic deformation (stage III) stages were quantitatively investigated by electron backscatter diffraction and digital image correlation. In stage I, it was found that 10.1% of the viewing zone underwent grain rotation or shape change, and the micro-strain was mainly distributed in primary α phase (αp) and their intersection. The result of the separately designed elastic loading-unloading tensile test showed that the rotated αp no longer returned to the primary orientation. In stage II, the tensile plastic deformation regions reached 52.9%, and grains in βT regions continued to rotate and began to change shape. In stage III, 84.6% of the viewing zone got into the tensile plastic deformation state. Combined with geometrically necessary dislocation density distribution, it was found that some of the regions in low strain state (0 ≤ ε<1%) actually underwent complex tensile plastic deformation. In addition, the maximum micro-strain of the viewing zone was transferred to βT regions.

Spinal deformity measurement using a low-density flexible array ultrasound transducer: A feasibility study with phantoms

Spinal deformities assessment using 3D ultrasound scanning has limitations in fitting onto different back surface contour as well as fitting within the gaps between subject and their spinal brace during bracing assessments. The study proposed a flexible array ultrasound transducer to overcome these limitations.The results demonstrated the feasibility of spinal deformity assessments with a flexible ultrasound array when arranged in four shapes, namely Linear, Concave, Convex, and S-shaped. For comparisons of imaging performance on spinous process using the four shapes, Convex and S-shaped transducer showed a depth dependence and lateral location dependence of the lateral intensity distribution of spinous process, respectively. S-shaped transducer had the least accurate prediction of the location of spinous process, with measurement error of 4.8 ​± ​3.2 ​mm, it also showed poorer prediction on spinal curvature measurements. This is suggested to be due to the asymmetrical distortion to the spinous process due to the lateral location dependence of the image. However, the coronal curve prediction of spine phantom performed well with R-squared values of >0.97 in all transducer shapes.The results of this study paved the way for further investigation on the improvement of image quality and measurement accuracy under different shapes for the flexible array, mechanism of dynamic shape change during the scanning to fit different body contour, as well as extension from 1D to 2D flexible array.

Platelet phenotype in children with ANKRD26-related thrombocytopenia

The mechanisms of hemorrhagic manifestations in patients with ANKRD26associated thrombocytopenia (ANKRD26-AT) are poorly understood. The aim of this work is to detect possible morpho-functional disorders of platelets in patients with mutations in the ANKRD26gene by flow cytometry with activation. The study was approved by the Independent Ethics Committee of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology. 8 children aged from 1.5 to 15 years were examined. The platelet count ranged from 29 to 172 thousand/μl, with a median of 60 thousand/μl. The severity of hemorrhagic manifestations was assessed on a standardized scale (Pediatric Bleeding Questionnaire, PBQ) and it ranged from 0 to 5 points, with a median of 3.5 points. Platelet activation was performed with a CRP + TRAP mixture. Comparison was carried out with the results of examination of 26 apparently healthy children (control group, CG) aged 2 to 15 years. When compared with CG, patients showed an increase in platelet size (FSC; p= 0.018) and granularity (SSC; p&lt; 0.001) after activation. In contrast to the CG, the correlation between FSC and SSC of platelets in patients was not significant (cor. = 0.55; p= 0.15). Patients showed a high, significant relationship between the number and FSC of platelets (cor. = –0.93; p&lt; 0.001), as well as an increased density of CD42b (p &lt; 0.001) and a decrease in the proportion of procoagulant platelets (p= 0.01) after activation. The revealed changes indicate violations of the mechanisms of activation and shape changes of platelets in patients with ANKRD26-AT.

Alkylammonium Halides for Facet Reconstruction and Shape Modulation in Lead Halide Perovskite Nanocrystals.

ConspectusThe interactions of halides and ammonium ions with lead halide perovskite nanocrystals have been extensively studied for improving their phase stability, controlling size, and enhancing their photoluminescence quantum yields. However, all these nanocrystals, which showed intense and color tunable emissions, mostly retained the six faceted cube or platelet shapes. Shape tuning needs the creation of new facets, and instead of composition variations by foreign ions interactions/substitutions, these require facet stabilizations with suitable ligands. Among most of the reported cases of lead halide perovskites, alkyl ammonium ions are used as a capping agent, which substituted in the surface Cs(I) sites of these nanocrystals. Hence, new surface ligands having a specific binding ability with different facets other than those in cube/platelet shapes are required for bringing stability to new facets and, hence, for tuning their shapes.In this Account, interactions of alkyl ammonium ions on the surface of perovskite nanocrystals and their impact on surface reconstructions are reviewed. Emphasizing the most widely studied CsPbBr3 nanocrystals, the usefulness and impact of alkyl ammonium ions on the phase stability, high-temperature annealing, enhancement of the brightness and doping in these nanocrystals are first discussed. Then, nanocrystals formed under limited primary alkyl ammonium ions and also with specific tertiary ammonium ions having new facets are elaborated. Further, the treatment of excess alkyl ammonium halides to these newly formed multifaceted polyhedron nanocrystals under different conditions, which led to armed and step-armed structures, are discussed. The change in optical properties during these shape transformations is also presented. Finally, the shape-change mechanism with alkyl ammonium halide-induced dissolutions of {200} and {112} facets and formation of {110} and {002} facets are discussed. Further, in summary, future prospects of new ligand designing for stabilizing new facets of perovskite nanocrystals and obtaining new shapes and properties are proposed.

A skeleton muscle model using GelMA-based cell-aligned bioink processed with an electric-field assisted 3D/4D bioprinting.

The most important requirements of biomedical substitutes used in muscle tissue regeneration are appropriate topographical cues and bioactive components for the induction of myogenic differentiation/maturation. Here, we developed an electric field-assisted 3D cell-printing process to fabricate cell-laden fibers with a cell-alignment cue.Methods: We used gelatin methacryloyl (GelMA) laden with C2C12 cells. The cells in the GelMA fiber were exposed to electrical stimulation, which induced cell alignment. Various cellular activities, such as cell viability, cell guidance, and proliferation/myogenic differentiation of the microfibrous cells in GelMA, were investigated in response to parameters (applied electric fields, viscosity of the bioink, and encapsulated cell density). In addition, a cell-laden fibrous bundle mimicking the structure of the perimysium was designed using gelatin hydrogel in conjunction with a 4D bioprinting technique.Results: Cell-laden microfibers were fabricated using optimized process parameters (electric field intensity = 0.8 kV cm-1, applying time = 12 s, and cell number = 15 × 106 cells mL-1). The cell alignment induced by the electric field promoted significantly greater myotube formation, formation of highly ordered myotubes, and enhanced maturation, compared to the normally printed cell-laden structure. The shape change mechanism that involved the swelling properties and folding abilities of gelatin was successfully evaluated, and we bundled the GelMA microfibers using a 4D-conceptualized gelatin film.Conclusion: The C2C12-laden GelMA structure demonstrated effective myotube formation/maturation in response to stimulation with an electric field. Based on these results, we propose that our cell-laden fibrous bundles can be employed as in vitro drug testing models for obtaining insights into the various myogenic responses.

Biomimetic 4D printed materials: A state-of-the-art review on concepts, opportunities, and challenges

The additive manufacturing is a transformative technique which improves the mechanical properties, e.g., the strength of the fabricated light weight industrial products. CAD softwares are integrated in the rapid prototyping setup and fabrication of the product is done through bottom-to-top approach via layer-wise deposition using stereo lithography file format as input. The 4D printed biomimetic materials are having shape changing capabilities, i.e., stimuli responsive features such as heat and thermal sensitivity, electromagnetic sensitivity, so, and so forth, as that comes under the fourth dimension. 4D printing is not just the extended technique of 3D printing but also the manufacturing technique of fabricating complex three-dimensional objects which can change the shape and forms when they are exposed to external environmental stimuli. 4D printing is appending one more dimension in the 3D printing, i.e., time. The review paper covers all aspects related to shape changing mechanisms from conceptual to actual design and emphasize has been given to the modern advancements in biomimetic 4D printing and sustainable biomedical and environmental applications.

4D printing of materials for the future: Opportunities and challenges

The concept of 4D printing is its formation of complex three-dimensional structures that have the ability to adopt different shapes and forms when subjected to different environmental stimuli. A few researchers simply view 4D printing as an extended technique of 3D printing or additive manufacturing with the added constraint of time. However, the unique shape change mechanism exhibited in this process is a combination of shape programming and the usage of smart active materials mostly polymers. This review article highlights the various smart materials, activation mechanisms and the shape-changing techniques employed in the 4D printing process. The potential of the shape-changing structures and their current applications in various biomedical and engineering fields is also explored. The article aims to emphasize the potential and viability of 4D printing and focused on providing an in-depth insight into the 4D printing process.

Fluorescence spectral shape analysis for nucleotide identification

We report a conjugated polyelectrolyte fluorescence-based biosensor P-C-3 and a general methodology to evaluate spectral shape recognition to identify biomolecules using artificial intelligence. By using well-defined analytes, we demonstrate that the fluorescence spectral shape of P-C-3 is sensitive to minor structural changes and exhibits distinct signature patterns for different analytes. A method was also developed to select useful features to reduce computational complexity and prevent overfitting of the data. It was found that the normalized intensity of 3 to 5 selected wavelengths was sufficient for the fluorescence biosensor to classify 13 distinct nucleotides and distinguish as little as single base substitutions at distinct positions in the primary sequence of oligonucleotides rapidly with nearly 100% classification accuracy. Photophysical studies led to a model to explain the mechanism of these fluorescence spectral shape changes, which provides theoretical support for applying this method in complicated biological systems. Using the feature selection algorithm to measure the relative intensity of a few selected wavelengths significantly reduces measurement time, demonstrating the potential for fluorescence spectrum shape analysis in high-throughput and high-content screening.

Pellicular Morphing Surfaces for Soft Robots

Soft structures in nature endow organisms across scales with the ability to drastically deform their bodies and exhibit complex behaviors while overcoming challenges in their environments. Inspired by microstructures found in the cell membranes of the Euglena family of microorganisms, which exhibit giant changes in shape during their characteristic euglenoid movement, this letter presents the design, fabrication, and characterization of bio-inspired deforming surfaces. The result is a surface of interconnected strips, that deforms in 2-D and 3-D due to simple shear between adjacent members. We fabricate flexible polymeric strips and demonstrate three different shapes arising out of the same actuation by imposing various constraints. We characterize the strips in terms of the force required to separate them and show that the bio-inspired cross section of these strips enables them to hold up to 8 N of force with a meagre 0.5 mm of material thickness, while still being flexible to deform. Further, the design of a soft robot module, with an actively deformable surface has been presented, which replicates the mechanism of shape change seen in the Euglena . This letter shows the potential for this new form of shape morphing surface in realizing bio-mimetic soft robots exhibiting large changes in shape.

Mechanisms and advanced photothermal modelling of laser-induced shape transformations of colloidal gold nanorods by nanosecond laser pulses.

We propose an advanced photothermal model based on a modified Takami model (MTM) to explain the mechanisms of shape changes of colloidal gold nanorods (NRs) induced by nanosecond laser pulses. This model takes into account the orientation of NRs, the radiative and convective losses, and the phase transitions of NRs. It was applied to the determination of the evolution of temperature and the shape and size transformations of NRs during the laser exposure. A series of measurements arising from the interaction between Au NRs and nanosecond laser pulses were analyzed by TEM measurements and the MTM model. We have demonstrated that the fragmentation and reshaping processes govern the nanoparticle (NP) shape. At high laser fluence, the complete fragmentation leads to a population of nearly spherical NPs, while at a moderate laser fluence, the partial fragmentation and reshaping processes generate a bimodal distribution. At low laser fluence, uncommon φ-shape NPs were produced as a result of the competition of cooling and reshaping processes. We also demonstrated that it is possible by the MTM model to determine the laser fluence required to suppress some specific NR shapes and to predict the NP size and shape distributions obtained after the laser exposure.

Sodium citrate stabilized Ag NPs under thermal treatment, electron-beam and laser irradiations

The stability of silver nanoparticles (Ag NPs) attracts an increasing attention because of the broadening field of their application, especially in catalysis, medicine and pharmacy, electronics and optoelectronics, sensors, environment protection technologies, textronics and many others. In this article, the stability of electrostatically stabilized aqueous dispersions of Ag NPs with different sizes under irradiation and thermal treatment is discussed. The UV–Vis spectrophotometry supported by Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM) were used to monitor the changes induced in Ag NPs by temperature, laser and electron-beam irradiation. It was found that the nature and mechanism of size and shape changes in Ag NPs treated by elevated temperature and radiation are different. KBr added to the reacting mixture as a size-control agent determines also the stability of investigated Ag NPs. The higher KBr content, the lower Ag NPs size, but surprisingly the highest thermal and photostability. Both thermal and radiation treatments lead to narrower distribution of Ag NPs sizes. The effects induced by laser light strongly depend on the relationship between the maximum of the plasmonic absorption band and wavelength of laser light. Small doses of electron beam radiation (≤ 100 Gy) does not change the NPs immediately. However a strong post radiation effect was found. The lower applied dose, the stronger effect observed.