Intrinsic Mechanical Stability Research Articles

Toward Ultrahigh Rate and Cycling Performance of Cathode Materials of Sodium Ion Battery by Introducing a Bicontinuous Porous Structure.

The emerging sodium-ion batteries (SIBs) are one of the most promising candidates expected to complement lithium-ion batteries and diversify the battery market. However, the exploitation of cathode materials with high-rate performance and long-cycle stability for SIBs has remained one of the major challenges. To this end, an efficient approach to enhance rate and cycling performance by introducing an ordered bicontinuous porous structure into cathode materials of SIBs is demonstrated. Prussian blue analogues (PBAs) are selected because they are recognized as a type of most promising SIB cathode materials. Thanks to the presence of 3D continuous channels enabling fast Na+ ions diffusion as well as the intrinsic mechanical stability of bicontinuous architecture, the resultant PBAs exhibit excellent rate capability (80 mAh g-1 at 2.5 A g-1) and ultralong cycling life (>3000 circulations at 0.5Ag-1), reaching the top performance of the reported PBA-based cathode materials. This study opens a new avenue for boosting sluggish ion diffusion kinetics in electrodes of rechargeable batteries and also provides a new paradigm for solving the dilemma that electrodes' failure due to high-stress concentration upon ion storage.

Nanomechanical footprint of SARS-CoV-2 variants in complex with a potent nanobody by molecular simulations.

Rational design of novel antibody therapeutics against viral infections such as coronavirus relies on surface complementarity and high affinity for their effectiveness. Here, we explore an additional property of protein complexes, the intrinsic mechanical stability, in SARS-CoV-2 variants when complexed with a potent antibody. In this study, we utilized a recent implementation of the GōMartini 3 approach to investigate large conformational changes in protein complexes with a focus on the mechanostability of the receptor-binding domain (RBD) from WT, Alpha, Delta, and XBB.1.5 variants in complex with the H11-H4 nanobody. The analysis revealed moderate differences in mechanical stability among these variants. Also, we identified crucial residues in both the RBD and certain protein segments in the nanobody that contribute to this property. By performing pulling simulations and monitoring the presence of specific native and non-native contacts across the protein complex interface, we provided mechanistic insights into the dissociation process. Force-displacement profiles indicate a tensile force clamp mechanism associated with the type of protein complex. Our computational approach not only highlights the key mechanostable interactions that are necessary to maintain overall stability, but it also paves the way for the rational design of potent antibodies that are mechanostable and effective against emergent SARS-CoV-2 variants.

Solid Oxide Fuel Cells for Aviation

Airbus has revealed ZEROe, three concepts for the world’s first zero-emission commercial aircraft which could be brought to market by 2035. The ZEROe concept aircrafts, which support Airbus’ commitment to lead the decarbonisation of the aviation industry, all rely on hydrogen as a primary power source, which would be deployed via a hybrid-hydrogen configuration featuring modified gas-turbine engines complemented by fuel cells for electrical power. Although the Proton Exchange Membrane (PEM) technology is one of the most matured fuel cell types, Airbus Central Research and Technology (CRT) is also investigating novel SOFC concepts for potential hybrid-hydrogen configurations.The Solid Oxide Fuel Cell (SOFC) offers major benefits, namely electrical efficiency and fuel versatility, for hybrid-electric aircraft propulsion. Although the SOFC’s area specific power density has drastically increased within the last decade, more needs to be done to make the technology accessible for aviation applications. The combined development of novel SOFC concepts and corresponding manufacturing processes are regarded as key objectives for the SOFC activities at Airbus Central Research and Technology. Airbus is designing, manufacturing and testing SOFC concepts with the aim to achieve highest gravimetric power densities.Novel manufacturing technologies for metallic and ceramic materials have the potential to enable lighter functional layers for SOFCs with increased intrinsic mechanical stability and surface area. Different cell concepts with an optimized current collection are currently under development at Airbus. The micro-tubular and monolithic SOFC are seen as the most promising concepts, whereas around 2 kW/kg on a cell level has recently been achieved in a performance test at Airbus.

Integration of feedforward and feedback control in the neuromechanics of vertebrate locomotion: a review of experimental, simulation and robotic studies.

Animal locomotion is the result of complex and multi-layered interactions between the nervous system, the musculo-skeletal system and the environment. Decoding the underlying mechanisms requires an integrative approach. Comparative experimental biology has allowed researchers to study the underlying components and some of their interactions across diverse animals. These studies have shown that locomotor neural circuits are distributed in the spinal cord, the midbrain and higher brain regions in vertebrates. The spinal cord plays a key role in locomotor control because it contains central pattern generators (CPGs) - systems of coupled neuronal oscillators that provide coordinated rhythmic control of muscle activation that can be viewed as feedforward controllers - and multiple reflex loops that provide feedback mechanisms. These circuits are activated and modulated by descending pathways from the brain. The relative contributions of CPGs, feedback loops and descending modulation, and how these vary between species and locomotor conditions, remain poorly understood. Robots and neuromechanical simulations can complement experimental approaches by testing specific hypotheses and performing what-if scenarios. This Review will give an overview of key knowledge gained from comparative vertebrate experiments, and insights obtained from neuromechanical simulations and robotic approaches. We suggest that the roles of CPGs, feedback loops and descending modulation vary among animals depending on body size, intrinsic mechanical stability, time required to reach locomotor maturity and speed effects. We also hypothesize that distal joints rely more on feedback control compared with proximal joints. Finally, we highlight important opportunities to address fundamental biological questions through continued collaboration between experimentalists and engineers.

Solid Oxide Fuel Cells for Aviation

The Solid Oxide Fuel Cell (SOFC) offers major benefits, namely electrical efficiency and fuel versatility, for hybrid-electric aircraft propulsion. The combined development of novel SOFC concepts and corresponding manufacturing processes are regarded as key objectives for the SOFC activities at Airbus Central Research and Technology. Airbus is designing, manufacturing and testing SOFC concepts with the aim to achieve highest gravimetric power densities. Novel manufacturing technologies for metallic and ceramic materials have the potential to enable lighter functional layers for SOFCs with increased intrinsic mechanical stability and surface area. Different cell concepts with an optimized current collection are currently under development at Airbus. The micro-tubular and monolithic SOFC are seen as the most promising concepts, whereas around 2 kW/kg on a cell level has recently been achieved in a performance test at Airbus.

Styrene-Based Poly(ethylene oxide) Side-Chain Block Copolymers as Solid Polymer Electrolytes for High-Voltage Lithium-Metal Batteries.

Herein, we report the design of styrene-based poly(ethylene oxide) (PEO) side-chain block copolymers featuring a microphase separation and their application as solid polymer electrolytes in high-voltage lithium-metal batteries. A straightforward synthesis was established, overcoming typical drawbacks of PEO block copolymers prepared by anionic polymerization or ester-based PEO side-chain copolymers. Both the PEO side-chain length and the LiTFSI content were varied, and the underlying relationships were elucidated in view of polymer compositions with high ionic conductivity. Subsequently, a selected composition was subjected to further analyses, including phase-separated morphology, providing not only excellent self-standing films with intrinsic mechanical stability but also the ability to suppress lithium dendrite growth as well as good flexibility, wettability, and good contacts with the electrodes. Furthermore, good thermal and electrochemical stability was demonstrated. To do so, linear sweep and cyclic voltammetry, lithium plating/stripping tests, and galvanostatic overcharging using high-voltage cathodes were conducted, demonstrating stable lithium-metal interfaces and a high oxidative stability of around 4.75 V. Consequently, cycling of Li||NMC622 cells did not exhibit commonly observed rapid cell failure or voltage noise associated with PEO-based electrolytes in Li||NMC622 cells, attributed to the high mechanical stability. A comprehensive view is provided, highlighting that the combination of PEO and high-voltage cathodes is not impossible per se.

Charting the Metal-Dependent High-Pressure Stability of Bimetallic UiO-66 Materials.

In theory, bimetallic UiO-66(Zr:Ce) and UiO-66(Zr:Hf) metal-organic frameworks (MOFs) are extremely versatile and attractive nanoporous materials as they combine the high catalytic activity of UiO-66(Ce) or UiO-66(Hf) with the outstanding stability of UiO-66(Zr). Using in situ high-pressure powder X-ray diffraction, however, we observe that this expected mechanical stability is not achieved when incorporating cerium or hafnium in UiO-66(Zr). This observation is akin to the earlier observed reduced thermal stability of UiO-66(Zr:Ce) compounds. To elucidate the atomic origin of this phenomenon, we chart the loss-of-crystallinity pressures of 22 monometallic and bimetallic UiO-66 materials and systematically isolate their intrinsic mechanical stability from their defect-induced weakening. This complementary experimental/computational approach reveals that the intrinsic mechanical stability of these bimetallic MOFs decreases nonlinearly upon cerium incorporation but remains unaffected by the zirconium: hafnium ratio. Additionally, all experimental samples suffer from defect-induced weakening, a synthesis-controlled effect that is observed to be independent of their intrinsic stability.

P‐129: Zero‐Stress Thin‐film Encapsulation Method for Increasing the Intrinsic Stability of Flexible OLEDs

A zero‐stress thin‐film encapsulation method was developed to mitigate residual stress. By keeping total residual stress at a minimum, the intrinsic mechanical stability of the encapsulated device was increased. The lifetimes of FOLEDs using the zero‐stress encapsulation method were increased by more than 35% compared with conventional encapsulation.

Prognostic value of an immediate lateral standing X-ray with a TLSO in patients with a thoracolumbar burst fracture

The final collapse of a “stable” thoracolumbar burst fracture is difficult to predict.This collapse was prospectively studied radiologically in patients with T12 or L1 burst fractures who, after evaluating the admission X-rays and the CT scan with the patients themselves, opted for a rigid thoracolumbar brace with support in the sternal manubrium (TLSO). On the other hand, patients with rigid braces sometimes have low back pain on follow-up (due to overload of the L5-S1 joints).Hypothesis: the standing lateral X-ray with only a TLSO for support (intrinsic mechanical stability) provides information on the final collapse and could also provide information on the low back pain.The study included 50 patients (20 males and 30 females, age: 63+14 years) admitted during 2011 and 2012, with 2 losses to follow-up. Variables: Farcy index and local kyphosis (Cobb at 3 vertebrae). X-rays: admission, with TLSO (immediate: Rx0), and at 3 and 6 months. They were compared with the final clinical and radiological results.It was decided to surgically intervene in 4 patients after Rx0.There were no painful sequelae at the fracture level, and 16/44 (31%) had low back pain.Using linear regression mathematical models, the increase in the Farcy index (Rx0-Rx admission) was associated with the appearance of low back pain and with local kyphosis (Rx0-Rx admission), and with the final kyphosis.It is advisable to perform a lateral standing X-ray after TLSO for information on the final collapse of the fracture and the appearance of accompanying low back pain.

Valor pronóstico de la radiografía lateral inmediata en bipedestación con TLSO en pacientes con fractura estallido toracolumbar

The final collapse of a “stable” thoracolumbar burst fracture is difficult to predict.This collapse was prospectively studied radiologically in patients with T12 or L1 burst fractures who, after evaluating the admission x-rays and the CT scan with the patients themselves, opted for a rigid thoracolumbar brace with support in the sternal manubrium (TLSO). On the other hand, patients with rigid braces sometimes have low back pain on follow-up (due to overload of the L5-S1 joints).Hypothesis: the standing lateral x-ray with only a TLSO for support (intrinsic mechanical stability) provides information on the final collapse and could also provide information on the low back pain.The study included 50 patients (20 males and 30 females, age: 63+14 years) admitted during 2011 and 2012, with 2 losses to follow-up. Variables: Farcy index and local kyphosis (Cobb at 3 vertebrae). X-Rays: admission, with TLSO (immediate: Rx0), and at 3 and 6 months. They were compared with the final clinical and radiological results.It was decided to surgically intervene in 4 patients after Rx0.There were no painful sequelae at the fracture level, and 16/44 (31%) had low back pain.Using linear regression mathematical models, the increase in the Farcy index (Rx0-Rx admission) was associated with the appearance of low back pain and with local kyphosis (Rx0-Rx admission), and with the final kyphosis.It is advisable to perform a lateral standing X-ray after TLSO for information on the final collapse of the fracture and the appearance of accompanying low back pain.

Large-Scale Silicone-Rubber-Based Optical Interconnect Packaged With FR4

Polydimethylsiloxane (PDMS)-based large-scale electrical-optical circuit boards (EOCBs) have been developed based on a combination of a large-scale PDMS waveguide fabrication technique and a process for efficient interfacial bonding between PDMS optical layers and standard FR4 (fiberglass-reinforced epoxy and grade 4 on flame retardance) printed circuit board materials using a specially developed surface adhesion promoter (SAP). The main mechanism of forming a good bonding between PDMS and FR4 has been identified. The optical properties of the PDMS waveguide layer remained unchanged by the addition of the SAP. According to the defined test procedures from the Institute of Printed Circuits, the International Electro Technical Commission, and Telcordia, the environmental stability of packaged EOCBs has been tested with the result that they exhibited excellent mechanical, optical, and thermal stabilities. The mechanical stability limit of the tested EOCBs is determined only by the intrinsic mechanical stability of the used PDMS materials. The optical waveguide propagation loss at 850 nm is less than 0.1 dB/cm after surviving from the defined environmental test procedures.

Realization of KaptonTM based optical interconnect by KMnO4 wet etching

In the paper, based on KMnO4 wet-etching technology PDMS (polydimethylsiloxane) based flexible optical interconnect packaged with KaptonTM (Dupont) foils was successfully realized through a stable and effective bonding technology. The optical and mechanical properties of the PDMS waveguide layer remained unchanged before and after packaging with KMnO4 etched Kapton foils. The mechanical stability limit of the tested optical interconnects is determined only by the intrinsic mechanical stability of the used PDMS materials. The optical loss at 850 nm is <0.05 dB/cm even after temperature treatments up to lead-free soldering temperatures of 260°C. In addition, the main mechanism of forming a good bonding between PDMS and Kapton foil was identified and analyzed as well.

Cost-effective waveguide integration method for large-scale electrical-optical-circuit-board production

Based on KMnO 4 wet etching technology, a low-cost waveguide integration technique of polydimethysiloxane (PDMS) based electrical-optical-circuit-board (EOCB) with FR4 substrates was developed, which is quite suitable for large-scale EOCB production. The optical and mechanical properties of the PDMS waveguide layer remained unchanged before and after waveguide integration. The mechanical stability limit of the tested EOCBs is determined only by the intrinsic mechanical stability of the used PDMS materials. The optical waveguide propagation loss at 850 nm is less than 0.1 dB/cm after surviving the defined environmental test procedures.

Polysiloxane based flexible electrical–optical-circuits-board

In the paper, a packaging technique of polysiloxane based flexible electrical–optical-circuits-board (EOCB) with Kapton (Dupont) foils was developed and introduced. The main mechanism of forming a good bonding between polysiloxane and Kapton foil was identified and verified. The optical and mechanical properties of the polysiloxane waveguide layer remained unchanged before and after packaging. According to the defined procedures, the environmental stability of packaged EOCBs has been tested with the result that they exhibited excellent mechanical, optical, and thermal stabilities. The mechanical stability limit of the tested EOCBs is determined only by the intrinsic mechanical stability of the used polysiloxane materials. The optical waveguide propagation loss at 850 nm is less than 0.1 dB/cm after surviving from the defined environmental test procedures.

Reducing antenna mechanical noise in precision spacecraft tracking

Doppler tracking of deep space probes is central to spacecraft navigation and many radio science investigations. The most sensitive Doppler observations to date were taken using the NASA/JPL Deep Space Network antenna DSS 25 (a 34 m diameter beam‐waveguide station instrumented with simultaneous X‐ and Ka‐band uplink and tropospheric scintillation calibration equipment) tracking the Cassini spacecraft. Those observations achieved Doppler fractional frequency stability (Doppler frequency fluctuation divided by center frequency, Δf/fo) ≈ 3 X 10−15 at 1000 s integration time. The leading noise in these very‐high‐sensitivity tracks was time‐dependent unmodeled motion of the ground antenna's phase center (caused, e.g., by antenna sag as elevation angle changes, unmodeled subreflector motion, wind loading, bulk motion of the antenna as it rolled over irregularities in its azimuth ring, etc.). This antenna mechanical noise has seemed irreducible since it is not clear how to build a large, moving, steel structure with intrinsic mechanical stability better than that of current tracking stations. Here we show how intrinsic mechanical noise of a large tracking antenna can be suppressed when two‐way Doppler tracking data and receive‐only Doppler data from a stiffer antenna are combined with suitable delays. Using this time delay correction procedure, the mechanical noise in the final Doppler observable can be reduced to that of the stiffer antenna. We demonstrate proof‐of‐concept experimentally and briefly discuss some practical considerations.

Protein–Protein Interaction Regulates Proteins’ Mechanical Stability

Elastomeric proteins are molecular springs found not only in a variety of biological machines and tissues, but also in biomaterials of superb mechanical properties. Regulating the mechanical stability of elastomeric proteins is not only important for a range of biological processes, but also critical for the use of engineered elastomeric proteins as building blocks to construct nanomechanical devices and novel materials of well-defined mechanical properties. Here we demonstrate that protein–protein interactions can potentially serve as an effective means to regulate the mechanical properties of elastomeric proteins. We show that the binding of fragments of IgG antibody to a small protein, GB1, can significantly enhance the mechanical stability of GB1. The regulation of the mechanical stability of GB1 by IgG fragments is not through direct modification of the interactions in the mechanically key region of GB1; instead, it is accomplished via the long-range coupling between the IgG binding site and the mechanically key region of GB1. Although Fc and Fab bind GB1 at different regions of GB1, their binding to GB1 can increase the mechanical stability of GB1 significantly. Using alanine point mutants of GB1, we show that the amplitude of mechanical stability enhancement of GB1 by Fc does not correlate with the binding affinity, suggesting that binding affinity only affects the population of GB1/human Fc (hFc) complex at a given concentration of hFc, but does not affect the intrinsic mechanical stability of the GB1/hFc complex. Furthermore, our results indicate that the mechanical stability enhancement by IgG fragments is robust and can tolerate sequence/structural perturbation to GB1. Our results demonstrate that the protein–protein interaction is an efficient approach to regulate the mechanical stability of GB1-like proteins and we anticipate that this new methodology will help to develop novel elastomeric proteins with tunable mechanical stability and compliance.