Assembly Interface Research Articles

Peptide-Guided Metal-Organic Frameworks Spatial Assembly Sustain Long-Lived Charge-Separated State to Improve Photocatalytic Performance.

The controlled fabrication of spatial architectures using metal-organic framework (MOF)-based particles offers opportunities for enhancing photocatalytic performances. The understanding of the contribution of assembly to a precise photocatalytic mechanism, particularly from the perspective of charge separation and extraction dynamics, still poses challenges. The present report presents a facile approach for the spatial assembly of zinc imidazolate MOF (ZIF-8), guided by β-turn peptides (SAZH). We investigated the dynamics of photoinduced carriers using transient absorption spectroscopy. The presence of a long-lived internal charge-separated state in SAZH confirms its role as an intersystem crossing state. The formation of an assembly interface facilitates efficient electron transfer from SAZH to O2, resulting in approximately 2.6 and 2 times higher concentrations of superoxide (·O2-) and hydrogen peroxide (H2O2), respectively, compared to those achieved with ZIF-8. The medical dressing fabricated from SAZH demonstrated exceptional biocompatibility and exhibited an outstanding performance in promoting wound restoration. It rapidly achieved hemostasis during the bleeding phase, followed by a nearly 100% photocatalytic killing efficiency against the infected site during the subsequent inflammatory phase. Our findings reveal a pivotal dynamic mechanism underlying the photocatalytic activity of control-assembled ZIF-8, providing valuable guidelines for the design of highly efficient MOF photocatalysts.

Bioadhesive-Inspired Ionomer for Membrane Electrode Assembly Interface Reinforcement in Fuel Cells.

Anion exchange membrane fuel cells promise a sustainable and ecofriendly energy conversion pathway yet suffer from insufficient performance and durability. Drawing inspiration from mussel foot adhesion proteins for the first time, we herein demonstrate catechol-modified ionomers that synergistically reinforce the membrane electrode assembly interface and triple-phase boundary inside catalyst layers. The resulting ionomers present exceptional alkaline stability with only slight ionic conductivity declines after treatment in 2 M NaOH aqueous solution at 80 °C for 2500 h. Adopting catechol-modified ionomer as both anion exchange membrane and binder achieves a single-cell performance increase of 34%, and more importantly, endows fuel cell operation at a current density of 0.4 A cm-2 for over 300 h with negligible performance degradation (with a cell voltage decay rate of 0.03 mV h-1). Combining theoretical and experimental investigations, we reveal the molecular adhesion mechanism between the catechol-modified ionomer and Pt catalyst and illuminate the effect on the catalyst layer microstructure. Of fundamental interest, this bioadhesive-inspired strategy is critical to enabling knowledge-driven ionomer design and is promising for diverse membrane electrode assembly configurational applications.

Contact stress ultrasonic detection method based on contact acoustic resistance model

The size and distribution of the contact stress at the assembly interface will directly affect the connection performance of the mechanical joint. However, the rough assembly interface presents strong dielectric discontinuity and material nonlinearity, which become the bottleneck restricting the development of contact stress detection. How to obtain contact stress by nondestructive testing means has become an urgent problem to be solved. In this paper, a multi-layer interface contact stress detection method based on contact acoustic resistance model is proposed to solve the difficult problem of rough interface contact stress detection. Firstly, based on the formation mechanism of contact acoustic resistance of rough assembly interface, the equivalent contact acoustic resistance expression of contact layer is derived. Secondly, the contact mechanism of rough assembly interface is clarified, and the mapping relationship model between contact acoustic resistance and contact stress is constructed. On this basis, according to the transmission law of ultrasonic wave at different interfaces of multilayer acoustic impedance, the expression of acoustic transmission coefficient at the interface of variable acoustic impedance is obtained. A contact stress detection method based on contact stress-contact acoustic resistance coefficient and acoustic transmission coefficient is proposed. The correctness of the theoretical model is verified by the tensile testing machine, and the maximum error is 15.52 %. This method will provide powerful data support for the evaluation of assembly interface connection state.

Effect of electromagnetic force installation method on critically reinforced interference sizes and fatigue behavior of CFRP bolted joints

AbstractThe electromagnetic force dynamic installation (DI) method of interference fit fasteners has significant advantages in improving the quality of the assembly interface of composite structure. This study aims to investigate how improving assembly interface quality may help in achieving high‐precision interference‐fit joints in composites. Single‐lap joint specimens were prepared using electromagnetic installation technique, the fatigue life and failure behaviors of the joints under different bolt‐hole clearances were measured and analyzed experimentally. In addition, a three‐dimensional finite element model was developed to predict the radial pre‐compression stresses around the hole and the progressive failure behavior of various typical damage modes in carbon fiber‐reinforced polymer induced by the interference. The results show that the critical interference range for the DI‐composite bolted structure is 1.0%–1.2%. The fatigue life of the best interference (1.0%) and the worst interference (0%, neat fit) have a difference of 36 times in amplitude. The residual stress with uniform distribution and high amplitude reduces the stress concentration of the hole wall and improves the failure evolution of the loaded hole. The contribution of this study provides vital guidance for improving the fatigue performance of CFRP bolted structures using a novel DI method.Highlights I = 1.0% is the critical damage‐enhancing interference size for dynamically installation interference fit bolts with electromagnetic forces. The residual stress amplitude introduced by the interference does not increase uniformly as the interference size increases. Excessive interference significantly reduces the uniformity and magnitude of residual stresses. Under subsequent cyclic loading, the fifth layer near the inlet and outlet of the extruded lower laminate appears to be the critical ply of extrusion deformation, and severe damage is concentrated in the critical ply of deformation. The decrease of stress amplitude and the variation of mean stress are the mechanisms of fatigue life enhancement in interference fit joints under external cyclic loading.

Accelerated Bridge Construction Case: A Novel Low-Carbon and Assembled Composite Bridge Scheme

Modern bridge construction towards a higher degree of low carbonization and assembly has been the general trend, while developing and broadening the low-carbon and assembled-oriented Accelerated Bridge Construction (ABC) technology can better realize the trade-offs between construction quality, efficiency, cost and sustainability. In the current mainstream ABC technologies such as precast-assembled concrete bridge and assembled steel bridge schemes, it is difficult to achieve an excellent balance between the above multicriterion trade-offs. To this end, this paper proposes a novel low-carbon and assembled composite bridge scheme as an innovative case of ABC technology based on a 26.7 km-length urban viaduct project in China with urgent environmental protection and assembly demands. Construction sustainability, the comprehensive economy and low-carbon performance are well balanced by the collaborative application of new steel–concrete composite structures, the rapid assembly interface design and low-carbon material technologies. The proposed scheme has been applied to a completed real-scale bridge, and the whole construction process only experienced 105 days of effective time, accompanied with slight environmental interference and construction noise and a small amount of labor and equipment input. In addition, the safety of the bridge, the rationality of the design concept and the calculation method have been verified by the static and dynamic loading tests of the real-scale bridge.

2D Perovskite Nanosheet‐Driven Polymeric Nanocomposites as Gate Dielectrics for Flexible Negative‐Capacitance Applications

AbstractDesigning composite gate dielectrics tailored by incorporating inorganic perovskite nanofillers into a polymer matrix to develop flexible low‐voltage transistors can be challenging because homogeneous dispersion of nanomaterials in the matrix is difficult to achieve; thus, degradation of the electrically insulating properties of nanocomposite layers is often observed. In this study, nanocomposite dielectrics are presented that consist of 2D Ba5Ta4O15 nanosheets (BTO NSs) for the first time. Perovskite BTO is introduced using the Langmuir–Blodgett method to construct a precise and pinhole‐free interface for the homogeneous assembly of 2D nanosheets. Its high k value and ferroelectric properties, which arise from the perovskite structure, can be harnessed to achieve attractive polarization and remarkable electronic properties. The 2D BTO NSs can also be utilized as phase crystallization fillers to enhance the ferroelectric properties of polyvinylidene fluoride (PVDF). Additionally, the multilayer PVDF/perovskite nanosheet hybrid dielectric, which reaches an unprecedentedly high dielectric constant of 22.4, exhibits effective dielectric relaxation related to the interfacial induced ferroelectric polarization and decisive negative‐capacitance response.

Integrate augmented reality and force sensing devices to assist blind area assembly

Blind area assembly is one of the challenges of manual assembly. The obscured pose of occluded components can lead to errors and reduce assembly efficiency. It has been observed that the sense of touch is commonly used to localize the assembly interface to complete the assembly in the blind area. Based on this, a blind area assembly assistance system was developed, which integrates augmented reality and force sensing devices. The system estimates the component poses during the tactile localizing stage based on the measured forces and moments applied to the product by the components, and then overlays virtual models of the components in situ to support assembly in the blind area. A user study was conducted to evaluate the performance and user experience of the system. The results showed that the system could successfully track and visualize target components during the tactile localizing stage, demonstrating great performance and user experience. The target component visualization can expedite assembly in the blind area, improve the system ease-of-use, and reduce the perceived workload. Finally, the limitations of the research are discussed and some directions for future work are provided.

Effect of interference installation method on interfacial properties and fatigue failure behavior of bolted composite joints

A novel dynamic installation (DI) method is proposed to improve the problems of severe installation damage, small installable interference size, and low installation efficiency of traditional static installation (SI) methods for installing interference bolts in composite bolted structures. The stress distribution and CFRP damage around the hole wall due to interference fitting and subsequent cyclic loading were predicted by finite element simulations. In addition, the fatigue life of DI and SI specimens was evaluated and the fatigue failure mechanisms were discussed. The results showed that the DI method provides a visible improvement in fatigue life, which is about 4 times that of the SI interference specimens and 38 times that of the non-interference specimen. In addition, DI introduces relatively higher average residual compressive stresses than SI, especially at the inlet of the laminate, which also results in a more uniform distribution along the axial direction of DI specimens. Micromorphological analysis of the specimens after fatigue failure indicated that the uniform stress distribution and low initial installation damage at the assembly interface introduced by the DI method during interference fit prevents severe delamination and crack propagation in joints subjected to external cyclic loading, such as the SI specimen. Severe extrusion deformation of the hole wall and matrix crushing are the main failure modes of DI specimens. Therefore, it is necessary to improve the interference installation method of composite materials.

Enhancing room temperature performance of solid-state lithium cell via a facile solid electrolyte-cathode interface design

Herein, we report the enhanced electrochemical performance of a solid-state cell realized through an engineered solid electrolyte-cathode interface via a simple casting technique. The ceramic-in-polymer solid electrolyte sample with 15 wt% NASICON-type Li1·2Sn0·9Zr0·9Al0·2(PO4)3 ceramic filler in a P(VDF-HFP) matrix (CPSE15) showed the highest room temperature conductivity of ∼1.1 × 10−4 S cm−1 and lithium-ion transference number of ∼0.60. The symmetric Li|CPSE15|Li cell showed a consistent voltage profile with an over-potential of ∼45 mV for 750 h at a current density of 0.1 mA cm−2. CPSE15 slurry was directly cast onto the LiFePO4 (LFP) cathode layer using a doctor-blade coating method to obtain a cathode-electrolyte assembly. Subsequently, a full cell fabricated using this assembly and lithium metal delivered an initial discharge capacity of ∼157 mAh g−1 at 0.2C. Further, the cell exhibited ∼90 mAh g−1 discharge capacity at 1C and sustained 500 charge-discharge cycles at room temperature. The engineered interface in cathode-electrolyte assembly enabled this cell to outperform its conventionally fabricated counterpart with a stacked LFP cathode sheet and freestanding CPSE15 electrolyte membrane, which was attributed to a lower interfacial resistance (∼51%) of the former.

Light-sensitive phosphorylation regulates retinal IMPDH1 activity and filament assembly.

Inosine monophosphate dehydrogenase (IMPDH) is the rate-limiting enzyme in guanosine triphosphate (GTP) synthesis and assembles into filaments in cells, which desensitizes the enzyme to feedback inhibition and boosts nucleotide production. The vertebrate retina expresses two splice variants IMPDH1(546) and IMPDH1(595). In bovine retinas, residue S477 is preferentially phosphorylated in the dark, but the effects on IMPDH1 activity and regulation are unclear. Here, we generated phosphomimetic mutants to investigate structural and functional consequences of S477 phosphorylation. The S477D mutation resensitized both variants to GTP inhibition but only blocked assembly of IMPDH1(595) filaments. Cryo-EM structures of both variants showed that S477D specifically blocks assembly of a high-activity assembly interface, still allowing assembly of low-activity IMPDH1(546) filaments. Finally, we discovered that S477D exerts a dominant-negative effect in cells, preventing endogenous IMPDH filament assembly. By modulating the structure and higher-order assembly of IMPDH, S477 phosphorylation acts as a mechanism for downregulating retinal GTP synthesis in the dark when nucleotide turnover is decreased.

A 1280-Channel Neural Microelectrode Array With Complementary Wedge-Shaped 3D Assembly Interfaces

A 1280-Channel Neural Microelectrode Array With Complementary Wedge-Shaped 3D Assembly Interfaces

Doping-induced assembly interface for noninvasive in vivo local and systemic immunomodulation.

Peripheral neural interfaces, potent in modulating local and systemic immune responses for disease treatment, face significant challenges due to the peripheral nerves' broad distribution in tissues like the fascia, periosteum, and skin. The incongruity between static electronic components and the dynamic, complex organization of the peripheral nervous system often leads to interface failure, stalling circuit research and clinical applications. To overcome these, we developed a self-assembling, tissue-adaptive electrode composed of a single-component cocktail nanosheet colloid, including dopants, conducting polymers, stabilizers, and an MXene catalyst. Delivered via a jet injector to designated nerve terminals, this assembly utilizes reactive oxygen species to catalytically dope poly (3,4-ethylenedioxythiophene), enhancing π-π interactions between nanosheets, and yielding a conductive, biodegradable interface. This interface effectively regulates local immune activity and promotes sensory and motor nerve functional restoration in nerve-injured mice, while engaging the vagal-adrenal axis in freely moving mice, eliciting catecholamine neurotransmitter release, and suppressing systemic cytokine storms. This innovative strategy specifically targets nerve substructures, bolstering local and systemic immune modulation, and paving the way for the development of self-adaptive dynamic neural interfaces.

Evolutionary degeneration of septins into pseudoGTPases: impacts on a hetero-oligomeric assembly interface.

The septin family of eukaryotic proteins comprises distinct classes of sequence-related monomers that associate in a defined order into linear hetero-oligomers, which are capable of polymerizing into cytoskeletal filaments. Like actin and ⍺ and β tubulin, most septin monomers require binding of a nucleotide at a monomer-monomer interface (the septin "G" interface) for assembly into higher-order structures. Like ⍺ and β tubulin, where GTP is bound by both subunits but only the GTP at the ⍺-β interface is subject to hydrolysis, the capacity of certain septin monomers to hydrolyze their bound GTP has been lost during evolution. Thus, within septin hetero-oligomers and filaments, certain monomers remain permanently GTP-bound. Unlike tubulins, loss of septin GTPase activity-creating septin "pseudoGTPases"-occurred multiple times in independent evolutionary trajectories, accompanied in some cases by non-conservative substitutions in highly conserved residues in the nucleotide-binding pocket. Here, we used recent septin crystal structures, AlphaFold-generated models, phylogenetics and in silico nucleotide docking to investigate how in some organisms the septin G interface evolved to accommodate changes in nucleotide occupancy. Our analysis suggests that yeast septin monomers expressed only during meiosis and sporulation, when GTP is scarce, are evolving rapidly and might not bind GTP or GDP. Moreover, the G dimerization partners of these sporulation-specific septins appear to carry compensatory changes in residues that form contacts at the G interface to help retain stability despite the absence of bound GDP or GTP in the facing subunit. During septin evolution in nematodes, apparent loss of GTPase activity was also accompanied by changes in predicted G interface contacts. Overall, our observations support the conclusion that the primary function of nucleotide binding and hydrolysis by septins is to ensure formation of G interfaces that impose the proper subunit-subunit order within the hetero-oligomer.

Insights on the conformation and appropriate drug-target sites on retinal IMPDH1 using the 604-aa isoform lacking the C-terminal extension.

Retinitis pigmentosa (RP) accounts for 2 percent of global cases of blindness. The RP10 form of the disease results from mutations in isoform 1 of inosine 5'-monophosphate dehydrogenase (IMPDH1), the rate-limiting enzyme in the de novo purine nucleotide synthesis pathway. Retinal photoreceptors contain specific isoforms of IMPDH1 characterized by terminal extensions. Considering previously reported significantly varied kinetics among retinal isoforms, the current research aimed to investigate possible structural explanations and suitable functional sites for the pharmaceutical targeting of IMPDH1 in RP. A recombinant 604-aa IMPDH1 isoform lacking the carboxyl-terminal peptide was produced and underwent proteolytic digestion with α-chymotrypsin. Dimer models of wild type and engineered 604-aa isoform were subjected to molecular dynamics simulation. The IMPDH1 retinal isoform lacking C-terminal peptide was shown to tend to have more rapid proteolysis (~16% digestion in the first two minutes). Our computational data predicted the potential of the amino-terminal peptide to induce spontaneous inhibition of IMPDH1 by forming a novel helix in a GTP binding site. On the other hand, the C-terminal peptide might block the probable inhibitory role of the N-terminal extension. According to the findings, augmenting IMPDH1 activity by suppressing its filamentation is suggested as a suitable strategy to compensate for its disrupted activity in RP. This needs specific small molecule inhibitors to target the filament assembly interface of the enzyme.

Fixture layout optimization of large compliant ship part assembly for reducing and straightening butt clearance

Fixture layout is an essential factor in intelligent manufacturing in the shipbuilding industry, affecting assembly quality and efficiency. Its optimization has become an urgent problem in the assembly process of compliant parts. Traditional fixture layout depends on workers’ experience, which leads to butt clearance along the assembly interface. Thus, this article proposes a butt clearance control-oriented fixture layout optimization (BCCFLO) methodology. First, a method for calculating the part dimensional variation under the influence of fixture layout and fixture locating error is developed. Then, a constrained multi-objective integer nonlinear programming (CMINP) model is innovatively formulated to optimize the fixture layout. Furthermore, the non-dominated sorting genetic algorithm-II based on Latin hypercube sampling is designed to address the CMINP model. The case study illustrates and validates that the fixture layout achieved by the proposed method could significantly control the butt clearance for large compliant part assembly in the shipbuilding industry.

Design for mixed model final assembly line (DfMMFAL): a new tool for assembly interface identification based on assembly process planning

Purpose This paper aims to fulfil a need to identify assembly interfaces from existing products based on their Assembly Process Planning (APP). It proposes a tool to identify assembly interfaces responsible for reused components integration. It is integrated into a design for mixed model final assembly line approach by focusing on the identification of assembly interfaces as a generic tool. It aims to answer the problem of interfaces’ identification from the APP. Design/methodology/approach A tool is developed to identify assembly interfaces responsible for reused component integration. It is based on the use of a rule-based algorithm that analyses an APP and then submits the results to prohibition lists to check their relevance. The tool is then tested using a case study. Finally, the resulting list is subjected to a visual validation step to validate whether the identified interface is a real interface. Findings The results of this study are a tool named ICARRE which identify assembly interfaces using three steps. The tool has been validated by a case study from the helicopter industry. Research limitations/implications As some interfaces are not contained in the same assembly operations and therefore, may not have been identified by the rule-based algorithm. More research should be done by testing and improving the algorithm with other case studies. Practical implications The paper includes implications for new product development teams to address the difficulties of integrating reused components into different products. Originality/value This paper presents a tool for identifying interfaces when sources of knowledge do not allow the use of current methods.

Monolithic foam of oriented boron nitride bowl for selective oxidative dehydrogenation of propane and pollutant removal

Bowl-like structures have great potential in the field of catalysis, environmental remediation, energy storage, etc., because of the large surface area, porous structure, and buffer hollow space. Herein, we developed a unique approach to control the opening direction of bowl-like structures via self-assembly strategy at the gas/liquid interface of liquid B2O3 environment foam. BN@BPO4 self-supporting monolithic foam with oriented bowl-like structure was obtained, which is built by numerous oriented bowl-like blocks and shows a double layer structure with face-to-face opening. The opening size can be adjusted by changing the amount of Cu(NO3)2 additives that is beneficial for the production of hexagonal boron nitride (h-BN). We believe the as-generated h-BN can enhance the gas trapping capacity of liquid B2O3 environment foam to precisely control pressure differential between large and small bubbles and thus favors the oriented opening of bowl-like structure. Further, pure h-BN monolithic foam with oriented bowl-like structure prepared at higher temperature possessed multimodal hierarchically porous structure and excellent performance in the catalytic oxidative dehydrogenation of propane into propene and the removal of organic pollutants. This work provides an extended assembly interface strategy of oriented bowl-like structure materials for different applications.

Human PRPS1 filaments stabilize allosteric sites to regulate activity.

The universally conserved enzyme phosphoribosyl pyrophosphate synthetase (PRPS) assembles filaments in evolutionarily diverse organisms. PRPS is a key regulator of nucleotide metabolism, and mutations in the human enzyme PRPS1 lead to a spectrum of diseases. Here we determine structures of human PRPS1 filaments in active and inhibited states, with fixed assembly contacts accommodating both conformations. The conserved assembly interface stabilizes the binding site for the essential activator phosphate, increasing activity in the filament. Some disease mutations alter assembly, supporting the link between filament stability and activity. Structures of active PRPS1 filaments turning over substrate also reveal coupling of catalysis in one active site with product release in an adjacent site. PRPS1 filaments therefore provide an additional layer of allosteric control, conserved throughout evolution, with likely impact on metabolic homeostasis. Stabilization of allosteric binding sites by polymerization adds to the growing diversity of assembly-based enzyme regulatory mechanisms.

An Intelligent Identification Approach of Assembly Interface for CAD Models

Kinematic semantics is often an important content of a CAD model (it refers to a single part/solid model in this work) in many applications, but it is usually not the belonging of the model, especially for the one retrieved from a common database. Especially, the effective and automatic method to reconstruct the above information for a CAD model is still rare. To address this issue, this paper proposes a smart approach to identify each assembly interface on every CAD model since the assembly interface is the fundamental but key element of reconstructing kinematic semantics. First, as the geometry of an assembly interface is formed by one or more adjacent faces on each model, a face-attributed adjacency graph integrated with face structure fingerprint is proposed. This can describe each CAD model as well as its assembly interfaces uniformly. After that, aided by the above descriptor, an improved graph attention network is developed based on a new dual-level anti-interference filtering mechanism, which makes it have the great potential to identify all representative kinds of assembly interface faces with high accuracy that have various geometric shapes but consistent kinematic semantics. Moreover, based on the above-mentioned graph and face-adjacent relationships, each assembly interface on a model can be identified. Finally, experiments on representative CAD models are implemented to verify the effectiveness and characteristics of the proposed approach. The results show that the average assembly-interface-face-identification accuracy of the proposed approach can reach 91.75%, which is about 2%–5% higher than those of the recent-representative graph neural networks. Besides, compared with the state-of-the-art methods, our approach is more suitable to identify the assembly interfaces (with various shapes) for each individual CAD model that has typical kinematic pairs.

Mechanical property and sealing performance analysis of the diaphragm compressor cylinder head for the hydrogen refueling station under the mutation impact load

Abstract: Under the combined action of structure-process -load, the stiffness and stress distribution at the sealing interface of the ultra-high pressure diaphragm compressor cylinder head exhibit significant nonlinear and uncertain characteristics, resulting in damage to the sealing interface, diaphragm and sealing ring. This paper first establishes a finite element numerical model considering assembly process parameters based on sudden impact load conditions, and analyzes the dynamic characteristics under different assembly process parameters. It is found that some modal frequencies transition with bolt loosening. Then, the mechanical characteristics of the assembly interface of the compressor sealing system under sudden impact load were studied. The maximum equivalent stress at the assembly interface was 298.9 MPa, and the maximum deformation at the top of the air chamber was 0.167mm. Finally, the nonlinear effects of sealing ring compression rate, sealing ring diameter, and sealing groove structure on contact stress and sealing performance were obtained. The results show that as the compression ratio increases by 20% and 25%, the contact pressure at the sealing interface increases by 42.0% and 77.5%, respectively; When the compression rate is 25%, the width of the sealing groove increases by 0.5mm, and the maximum contact pressure decreases by 8.1%. The research on the dynamic characteristics and sealing performance of diaphragm compressors provides technical support for the structural optimization design of diaphragm compressors cylinder head.