Mechanical Rigidity Research Articles

Building rigid networks with prestress and selective pruning

Biopolymer networks from the intracellular to tissue scale display high rigidity and tensile stress while having coordinations well below the normal threshold for mechanical rigidity. The elastic filaments in these networks are often severed by enzymes in a tension-inhibited manner. The effects of such pruning on the mechanics of prestressed networks have not been studied. We show that networks pruned by a tension-inhibited method remain rigid at much lower coordinations than randomly pruned ones. These findings suggest a possible reason for the repeated evolution of tension-inhibited filament-severing proteins. Published by the American Physical Society 2024

Novel 2D Material of MBenes: Structures, Synthesis, Properties, and Applications in Energy Conversion and Storage.

2D transition metal borides (MBenes) have garnered significant attention from researchers due to their exceptional electrical conductivity, strong mechanical rigidity, excellent dynamic and thermodynamic stability, which stimulates the enthusiasm of researchers for the study of MBenes. Over the past few years, extensive research efforts have been dedicated to the study of MBenes, resulting in a growing number of synthesis methods being developed. However, there remains a scarcity of comprehensive reviews on MBenes, particularly in relation to the synthesis techniques employed. To address this gap, this review aims to provide a comprehensive summary of the latest research findings on MBenes. An exhaustive exploration of the crystal structure types of MBenes is presented, highlighting the greater structural diversity compared to MXenes. Furthermore, a comprehensive review of the recent advancements in MBenes synthesis methodologies is provided. The review also delves into the physical and chemical properties of MBenes, while elucidating their applications in the realms of energy conversion and energy storage. Lastly, this review concludes by summarizing and offering insights on MBenes from three angles: synthesis, structure-property relationships, and application prospects.

Effect of Sm2O3 on thermal, optical, mechanical, gamma and neutron shielding properties of zinc-boro-vanadate glasses

Abstract The effect of Sm2O3 on thermal, optical, mechanical, gamma and neutron shielding properties of newly prepared zinc borovanadate glasses has been investigated. Density is found increased and molar volume decreased with Sm2O3 content. The glass transition temperature ( T g ) , crystallization temperature ( T c ) and the peak crystallization temperature ( T P ) increased with increase of rare earth oxide content. These findings demonstrated an excellent glass-forming ability and thermal stability of the glasses. The optical properties have been explored through UV–vis spectroscopy. The indirect optical band gap energy ( E opt ) decreased from 2.978 to 2.679 eV, Urbach energy ( ∆ E ) increased from 0.273 to 0.299 eV and refractive index increased from 2.403 to 2.489 with increase in Sm2O3. Elastic moduli, Poisson’s ratio, Hardness and fractal bond connectivity were computed theoretically as per Makishima Mackenzie model. It is found that these glasses have appreciable mechanical strength and rigidity. Phy-X/PSD software has been used to determine different radiation shielding characteristics for the energy range 0.015–15 MeV. The mass and linear attenuation coefficients are found higher, and half value layer, tenth value layer and mean free paths are found lower than many radiation shielding glasses quoted in the literature values. The obtained Z eq values varied from 15.828–29.118 for energy range from 0.015 to 15 MeV, which are greater than those reported for several commercial glasses, concretes and rocks. Due to the Compton scattering process, exposure build up and energy absorption factor are found to be highest in the medium energy region. The fast neutron removal cross-sections of the glasses are observed to be significantly high. For the first time, thermally stable and mechanically strong zinc borovanadate glasses mixed with Sm2O3 have been thoroughly investigated for various properties and concluded that these glasses are suitable for optoelectronics and γ-shielding applications.

Toward Superior Stiffness in Carbon: The Interplay between Bond Strength and Anisotropic Response.

Carbon's ability to form diverse structures with varying hybridizations motivates the search for novel materials surpassing diamond's exceptional mechanical rigidity. We analyze previously predicted superhard phases and find that some exhibit average bond stiffness and density higher than those of diamond, hinting at potentially superior stiffness. However, these structures show a lower bulk modulus. We delve into this contradiction and demonstrate that it stems from the structures' anisotropic response to isotropic deformation. The concept of strain anisotropy is introduced to quantify this phenomenon. Our findings reveal a key connection between bond stiffness and bulk modulus in carbon materials, highlighting the importance of considering anisotropic behavior for a comprehensive understanding of the mechanical properties.

Stimulating the Electrostatic Interactions in Composite Cathodes Using a Slurry-Fabricable Polar Binder for Practical All-Solid-State Batteries

In this work, poly vinylidene fluoride–chlorotrifluoroethylene (PVdF-CTFE) is introduced as a slurry-fabricable polymer binder to fabricate a stable composite cathode using the complex materials of a Li[Ni0.7Co0.1Mn0.2]O2 cathode, Li6PS5Cl electrolyte, and super C carbon, for sulfide-based all-solid-state batteries (ASSBs). The high electronegativity of fluorine in the poly(vinylidene fluoride–chlorotrifluoroethylene (PVdF-CTFE) binder creates a polarized electronic environment in the composite cathode, promoting electrostatic interactions with Li ions. Compared with that of butadiene rubber (BR), the PVdF-CTFE binder has a stronger binding energy to the complex materials in the composite cathode, which enhances the mechanical rigidity of the composite cathode with highly uniform adhesion. In addition, uniform and close contact between the complex materials in the composite cathode reduces the resistance at the interfaces, lowering the energy barrier for Li+ diffusion, and eventually creates a fast Li+ diffusion pathway in the composite cathode. Thus, the pouch-type ASSBs cell, which comprises the composite cathode with the PVdF-CTFE binder, Li6PS5Cl electrolyte sheet, and silver-carbon (Ag/C) Li-free anode delivers a high reversible capacity of 198.5 mAh g–1 at 0.1 C and long-term cycling stability over 300 cycles with a capacity retention of 74.5 % at 0.5 C at 60 °C.

Evaluation of antibacterial activity on nanoline-array surfaces with different spacing

Extensive research has been conducted on anti-biofouling or antibacterial surfaces, with nanostructured surfaces that mimic cicada and dragonfly wings emerging as promising candidates for mechano-bactericidal applications. These biomimetic nanostructured surfaces are capable of exerting a bactericidal effect by directly damaging the membranes of bacteria attached to nanostructures. Although research on bactericidal effect using various nanostructures have been conducted, no specific studies have yet reported on the antibacterial efficiency of the surface having nanoline array, especially regarding the spacing between nanolines. This study details the fabrication of nanoline array via ultraviolet (UV) molding with polyurethane acrylate (PUA), noted for its UV sensitivity and rapid curing, enabling the fabrication of precise and scalable nanoscale structures. Investigation into the nanoline array’s antibacterial effects against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) reveals that nanoline spacing critically influences bacterial adherence and viability, with specific spacings enhancing antibacterial properties. Scanning electron microscopy (SEM) and confocal microscopy analyses show that surface topography significantly affects bacterial behavior, with specific spacings leading to varied bacterial responses, including membrane damage and altered attachment patterns. The study highlights the potential of nanoline array in fabricating surfaces with tailored antibacterial properties, emphasizing the importance of nanoscale design in influencing bacterial interaction and viability. We also confirm the relative mechanical rigidity of the nanoline array, which exhibits antibacterial effects, through both experimental observations and numerical analysis. This indicates our proposed nanoline-array surface could have potential future applications in mechanical anti-bacterial functions that require such structural robustness.

Shingled design lightweight photovoltaic modules using honeycomb sandwich structures as backsheets

The expanding scale of the photovoltaic (PV) market has intensified the focus on PV module designs for diverse applications. Research actively pursues lightweight PV modules, replacing front glass with polymer films as a suitable design solution. Lightweight PV modules with front-film structures require additional structures to compensate for their inadequate mechanical rigidity. Hence, we integrated honeycomb sandwich structures into lightweight PV modules, substituting them for traditional PV backsheets. It increased the mechanical rigidity of lightweight PV modules and effectively replaced the PV backsheet through a simple one-step lamination process. Consequently, we successfully fabricated lightweight PV modules with a shingled design, achieving a conversion power of 205.80 W in an area of 1.034 m2, facilitating the integration of more solar cells in a limited space. Additionally, standard reliability tests were performed on a PV module weighing only 6.2 kg/m2.

Mechanically rigid metallopeptide nanostructures achieved by highly efficient folding

AbstractNatural proteins must fold into complex three-dimensional structures to achieve excellent mechanical properties vital for biological functions, but this has proven to be exceptionally difficult to control in synthetic systems. As such, the long-standing issue of low mechanical rigidity and stability induced by misfolding constrains the physical and chemical properties of self-assembling peptide materials. Here we introduce a mixed-chirality strategy that enhances folding efficiency in topologically interlocked metallopeptide nanostructures. The orderly entanglement of heterochiral peptide-derived linkers can fold into a compact three-dimensional catenane. These folding-mediated secondary structural changes not only generate biomimetic binding pockets derived from individual peptide strands but also result in strong chiral amplification by the tight interlocking manner. Notably, this strategic ‘chirality mutation’ alters their arrangement into tertiary structures and is pivotal in achieving exceptional mechanical rigidity observed in the metallopeptide crystals, which exhibit a Young’s modulus of 157.6 GPa, approximately tenfold higher than the most rigid proteinaceous materials in nature. This unusual nature is reflected in enhanced peptide-binding properties and heightened antimicrobial activities relative to its unfolded counterpart.

Amylum forms typical self-assembled amyloid fibrils.

Amyloid fibril formation is a central biochemical process in pathology and physiology. Over decades, substantial advances were made in elucidating the mechanisms of amyloidogenesis, its links to disease, and the production of functional supramolecular structures. While the term "amyloid" denotes starch-like features of these assemblies, no evidence of amyloidogenic behavior of polysaccharides has been so far reported. Here, we investigate the potential of amylum (starch) not only to self-assemble into hierarchical fibrillar structures but also to exhibit canonical amyloidogenic properties. Ordered amylum structures were formed through a sigmoidal growth process with characteristic amyloid features including typical nanofibril morphology, binding to indicative dyes, inherent luminescence, apple-green birefringence upon Congo red staining, and notable mechanical rigidity. These findings shed light on polysaccharide self-assembly and expand the generic amyloid phenomenon.

Integrating local energetics into Maxwell-Calladine constraint counting to design mechanical metamaterials.

The Maxwell-Calladine index theorem plays a central role in our current understanding of the mechanical rigidity of discrete materials. By considering the geometric constraints each material component imposes on a set of underlying degrees of freedom, the theorem relates the emergence of rigidity to constraint counting arguments. However, the Maxwell-Calladine paradigm is significantly limited-its exclusive reliance on the geometric relationships between constraints and degrees of freedom completely neglects the actual energetic costs of deforming individual components. To address this limitation, we derive a generalization of the Maxwell-Calladine index theorem based on susceptibilities that naturally incorporate local energetic properties such as stiffness and prestress. Using this extended framework, we investigate how local energetics modify the classical constraint counting picture to capture the relationship between deformations and external forces. We then combine this formalism with group representation theory to design mechanical metamaterials where differences in symmetry between local energy costs and structural geometry are exploited to control responses to external forces.

Toward enhanced mechanical rigidity: additive manufacturing of auxetic tubes with PU core and comparative analysis of unique structural behaviors

Toward enhanced mechanical rigidity: additive manufacturing of auxetic tubes with PU core and comparative analysis of unique structural behaviors

Tension Induced Photoluminescence Enhancement in an Organic Single Crystal.

Organic single crystals possess distinct advantages due to their highly ordered molecular structures, resulting in improved stability, enhanced carrier mobility, and superior optical characteristics. However, their mechanical rigidity and brittleness impede the applications in flexible and wearable optoelectronic devices. Here, photoluminescence (PL) emission from 2,6-diphenylanthracene (DPA) single crystals is studied under tensile strain, which shows PL enhancement by more than two times with a strain of ≈1.42%. Such a tension induced PL enhancement is reversible, exhibiting no clear optical degradations during 100 cycles of bending and recovery processes. Theoretical calculations reveal that the deformation of molecular structure under strain induces a decrease of the dihedral between anthracene and benzene moieties in DPA molecules. Further, the increased molecular conjugation enhances the molecular oscillator strength, leading to the brightened PL emission. Meanwhile, with the decreased dihedral, the molecular vibrations in DPA crystals are suppressed, which can reduce the non-radiative decay rate. In contrast, no tension induced PL enhancement is observed in polycrystalline DPA thin films as the strain can be released via the grain boundaries. This study highlights the superior optical performance of DPA single crystals under strain field, which will provide new possibilities for DPA-based flexible devices.

In Situ Growth of COF/PVA-Carrageenan Hydrogel Using the Impregnation Method for the Purpose of Highly Sensitive Ammonia Detection.

Flexible ammonia (NH3) gas sensors have gained increasing attention for their potential in medical diagnostics and health monitoring, as they serve as a biomarker for kidney disease. Utilizing the pre-designable and porous properties of covalent organic frameworks (COFs) is an innovative way to address the demand for high-performance NH3 sensing. However, COF particles frequently encounter aggregation, low conductivity, and mechanical rigidity, reducing the effectiveness of portable NH3 detection. To overcome these challenges, we propose a practical approach using polyvinyl alcohol-carrageenan (κPVA) as a template for in the situ growth of two-dimensional COF film and particles to produce a flexible hydrogel gas sensor (COF/κPVA). The synergistic effect of COF and κPVA enhances the gas sensing, water retention, and mechanical properties. The COF/κPVA hydrogel shows a 54.4% response to 1 ppm NH3 with a root mean square error of less than 5% and full recovery compared to the low response and no recovery of bare κPVA. Owing to the dual effects of the COF film and the particles anchoring the water molecules, the COF/κPVA hydrogel remained stable after 70 h in atmospheric conditions, in contrast, the bare κPVA hydrogel was completely dehydrated. Our work might pave the way for highly sensitive hydrogel gas sensors, which have intriguing applications in flexible electronic devices for gas sensing.

Microstructural, mechanical, thermo‐rheological, barrier, and antimicrobial properties of coextruded tri‐layer polylactide/encapsulated geraniol/polylactide‐graphene nanoplatelets films

AbstractA sustainable polylactide (PLA)‐based multilayer food packaging film was developed to improve neat PLA films' modest mechanical, thermal, and water/gas barrier properties. To improve the desired properties and impart antimicrobial aspects to the composite films, graphene nanoplatelets (GNP), and geraniol (GER) were reinforced into single‐layered PLA films. The project aimed to assemble three monolayers into multilayer films (MLF) through a coextrusion process, keeping the PLA‐GER layer in the core. X‐ray diffractograms, micrographs, and roughness parameters of the films demonstrated the dispersion of GNP in the film. Thermogravimetric analysis confirmed an enhancement in the thermal stability of the MLF by around 8°C when compared against single‐layer PLA films. An improvement in mechanical rigidity was supported by tensile (>87%) and rheological measurements. The polymers exhibit liquid‐like behavior in melts. Barrier properties did not improve for the MLF due to the agglomeration of GNP. The excellent antimicrobial properties of the MLFs for 3 weeks of storage at refrigerated conditions against both gram‐positive and gram‐negative pathogens were attributed to the release of GER from the film into the packed chicken samples and proved their potential for use in the food industry.

Viscoelastic Adhesive, Super-Conformable, and Semi-Flowable Liquid Metal Eutectogels for High-Fidelity Electrophysiological Monitoring.

Integrating gels with human skin through wearables provides unprecedented opportunities for health monitoring technology and artificial intelligence. However, most conductive hydrogels, organogels, and ionogels lack essential environmental stability, biocompatibility, and adhesion for reliable epidermal sensing. In this study, we have developed a liquid metal eutectogel simultaneously possessing superior viscoelasticity, semiflowability, and mechanical rigidity for low interfacial skin impedance, high skin adhesion, and durability. Liquid metal particles (LMPs) are employed to generate free radicals and gallium ions to accelerate the polymerization of acrylic acid monomers in a deep eutectic solvent (DES), obtaining highly viscoelastic polymer networks via physical cross-linking. In particular, graphene oxide (GO) is utilized to encapsulate the LMPs through a sonication-assisted electrostatic assembly to stabilize the LMPs in DES, which also enhances the mechanical toughness and regulates the rheological properties of the eutectogels. Our optimized semi-flowable eutectogel exhibits viscous fluid behavior at low shear rates, facilitating a highly conformable interface with hairy skin. Simultaneously, it demonstrates viscoelastic behavior at high shear rates, allowing for easy peel-off. These distinctive attributes enable the successful applications of on-skin adhesive strain sensing and high-fidelity human electrophysiological (EP) monitoring, showcasing the versatility of these ionically conductive liquid metal eutectogels in advanced personal health monitoring.

Predictive modeling of pH on the transport of Co(II) Ions from aqueous solutions through supported ceramic polymer membrane

Optimal pH is essential for efficient cobalt extraction from polymeric membrane systems, with D2EHPA used as an extractant for Co(II) at pH < 7, achieving 47% efficiency. The pH of piperazine as a stripping agent increases to a concentration of 0.48 M, and the extraction efficiency of Co(II) > 80%. Depending on the functional group of (C4H10N2), the optimal pH for separation was 9.8. The study revealed that pKa value was calculated to predict the ideal pH, and its value was 9.73, which is nearly to the pH, since the pH of the strip concentration and the properties of the membrane affect the extraction of cobalt at 30 °C. The partition ratio indicates the high distribution of the extract in supported ceramic polymer membrane (SCPM). The ceramic component provides mechanical strength and rigidity to the overall membrane structure, allowing it to withstand high pressures and temperatures during operation Study various factors such as the effect of pH on the ionization of the extract; effect of pH on band ionization; effect of pH on the temperature in the extract, effect of pH on the solute, effect of the band at different pH ranges and a comparison was made between the predictive model and experimental data that was proven through mathematical modeling using the MATLAB program.

Microstructural, physicochemical, thermal, and rheological properties of buckwheat flour treated with high-pressure at selected moisture contents

This study investigated the role of water in the high-pressure treatment (300–600 MPa/15 min) of buckwheat (Fagopyrum esculentum) flour and property changes in post-process samples. DSC and XRD measurements demonstrated complete gelatinization of buckwheat starch occurred at 600 MPa. The particle size of flour decreased above 450 MPa. HP-treatment successfully transformed the crystalline A-type structure of hydrated samples into a B-type structure. Dry samples did not gelatinize or exhibit any structural change, even at 600 MPa. The progress of gelatinization and gel rigidity of post-process samples were measured on a rheometer. The thermal transition captured in rheometer and DSC differs significantly. The impact of further heating on the pressurized samples resulted in a significant improvement in their mechanical rigidity. Overall, this study confirmed that an optimum flour-to-water ratio should be maintained during HP treatment to achieve the desired changes in buckwheat flour so that it could be used in food formulation.

Research on optimizing ultrasonic frequencies for efficient single-walled carbon nanotube dispersion in water using a focused ultrasonic system

Single-walled carbon nanotubes (SWCNTs) can be applied in a wide range of fields owing to their excellent mechanical rigidity, electrical conductivity, and thermal conductivity. However, their application is limited because of their strong van der Waals forces and poor dispersion owing to their hydrophobic properties. To address this problem, ultrasonic dispersion technology has been used in the industry. However, very few studies have investigated the surface damage or effectiveness of the surfactants of SWCNTs with a focus on the frequencies of specific ultrasonic equipment. In this study, the dispersibility of SWCNTs at frequencies of 270, 400, and 700 kHz was investigated using a new focused ultrasonic instrument. The dispersion stability of the samples was analyzed according to each frequency, and the SWCNT surface was studied in detail using field-emission transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy. The adsorption of the polymeric surfactant to the SWCNT was most observed at 270 kHz, and the dispersion stability after processing at this frequency was better than that of the other samples. Therefore, the frequency of the ultrasonic intensity has a direct effect on the surface modification of SWCNTs.

Enhancing Blood Pressure Sensitivity: Innovative C-Shaped Slot Design in Microsensor Systems

Abstract In this article, we successfully developed and simulated a wearable pressure sensor for monitoring blood pressure. This sensor utilizes MEMS technology and is based on LC wireless, eliminating the need for a battery system. The sensor is constructed with a metal-insulator-metal capacitive design, featuring a diaphragm measuring 1.1 mm × 1.1 mm and with a thickness of 22 µm. Furthermore, we devised a unique C-shaped circular slot diaphragm to enhance sensitivity by reducing the mechanical rigidity of the membrane. Our design and simulation were conducted using COMSOL Multiphysics. From our findings, we observed that the frequency response to varying pressure ranged from 285 to 445 MHz. Additionally, our results yielded a mechanical sensitivity of 125.7 nm/mmHg, along with a sensor sensitivity of 1.49 fF/mmHg. Notably, the sensor with the novel C-shaped circular slot diaphragm exhibited high-pressure sensitivity, surpassing that of a clamped diaphragm by 15.5%.

Investigation of Thermomechanical and Dielectric Properties of PLA-CA 3D-Printed Biobased Materials

Renewable dielectric materials have attracted the attention of industries and stakeholders, but such materials possess limited properties. This research focused on studying polylactic acid (PLA)/cellulose acetate (CA) blends produced by 3D printing to facilitate their integration into the electrical insulation field. The dielectric findings showed that a blend containing 40% of CA by weight had a dielectric constant of 2.9 and an electrical conductivity of 1.26 × 10−11 S·cm−1 at 100 Hz and 20 °C while exhibiting better mechanical rigidity in the rubbery state than neat PLA. In addition, it was possible to increase the electrical insulating effect by reducing the infill ratio at the cost of reduced mechanical properties. The differential scanning calorimetry, broadband dielectric spectroscopy, and dynamic mechanical analysis results showed that the PLA plasticizer reduced the energy required for PLA relaxations. These preliminary results demonstrated the benefits of using a combination of PLA, CA, and 3D printing for electrical insulation applications.