Assembly Of Structures Research Articles

ДОСЛІДЖЕННЯ ДИНАМІЧНИХ ПАРАМЕТРІВ Н-РОТОРІВ ДАР’Є ЗМІННОЇ КОНФІГУРАЦІЇ

Calculations of the natural frequencies and forms of oscillations of a typical structural assembly of the H-rotor design of Dareus were carried out. It includes a sliding traverse and a blade fixed at its end. The dependencies of the eigenfrequencies of the extendable traverse-blade unit on the number of the vibration form at different values of the traverse extension value, as well as the dependence of the eigenfrequencies on the degree of traverse extension for five forms of oscillations, were obtained.

Insights into the assembly process and properties of regenerated cellulose beads prepared in alkali/urea aqueous solutions

Taking the perspective of cellulose molecular chain assembly via the “bottom-top” route, we delve into the influence of both the cellulose solution and the coagulation bath on the assembly process and structure of regenerated cellulose beads (RCBs). The results show that cellulose molecular weight, mass fraction, and the presence of surfactant have an impact on RCBs. Contrary to traditional views where the structures of material are determined by solvent-nonsolvent exchange rate, ion-cellulose binding capacity also affects RCBs. Overall, the influence of ions follows the Hofmeister sequence. Kosmotropes promote the assembly of cellulose chains and elementary fibers, leading to “salting out” effects, reduced pore size of RCBs, increased crystallinity, and enhanced mechanical properties. In contrast, chaotropes induce “salting in” effects, resulting in opposite outcomes. The average pore size of RCBs coagulated in NaSCN solution was approximately 15-folds larger than those prepared in sodium citrate solution. Anions have a greater impact than cations, and both “salting out” and “salting in” effects strengthen with concentration. Temperature variations primarily affect solvent and nonsolvent exchange speed during cellulose regeneration. These findings provide new insights into regulating RCBs, enabling tailored performance for different applications.

Concrete structure assembly technology based on 3D intelligent image analysis

AbstractAt present, there is no standard practice for temporary connection of component installation. How to make temporary connections to components more efficient and accurate is the key to the construction of cast‐in‐place connection parts in concrete prefabricated buildings. In order to improve the assembly technology of concrete structures, this paper combines three‐dimensional intelligent image analysis technology for simulation, analyzes and compares several common electronic image stabilization algorithms, discusses the video image stabilization technology based on gray projection method in detail, and gives experimental results. Moreover, this paper analyzes and compares common moving target tracking algorithms, such as feature‐based tracking, region matching‐based tracking, dynamic contour‐based tracking, and 3D model‐based tracking. In addition, this paper studies the target tracking algorithm based on the Camshift algorithm, and constructs the assembly model of the intelligent concrete structure with the support of the algorithm. Through experimental verification, it is known that the performance distribution of the concrete structure assembly model based on 3D intelligent image analysis in experimental evaluation is between [81, 89], the experimental study shows that the concrete structure assembly model based on 3D intelligent image analysis can effectively improve the assembly effect of concrete structure.

Elucidating Structural Configuration of Lipid Assemblies for mRNA Delivery Systems.

The development of mRNA delivery systems utilizing lipid-based assemblies holds immense potential for precise control of gene expression and targeted therapeutic interventions. Despite advancements in lipid-based gene delivery systems, a critical knowledge gap remains in understanding how the biophysical characteristics of lipid assemblies and mRNA complexes influence these systems. Herein, we investigate the biophysical properties of cationic liposomes and their role in shaping mRNA lipoplexes by comparing various fabrication methods. Notably, an innovative fabrication technique called the liposome under cryo-assembly (LUCA) cycle, involving a precisely controlled freeze-thaw-vortex process, produces distinctive onion-like concentric multilamellar structures in cationic DOTAP/DOPE liposomes, in contrast to a conventional extrusion method that yields unilamellar liposomes. The inclusion of short-chain DHPC lipids further modulates the structure of cationic liposomes, transforming them from multilamellar to unilamellar structures during the LUCA cycle. Furthermore, the biophysical and biological evaluations of mRNA lipoplexes unveil that the optimal N/P charge ratio in the lipoplex can vary depending on the structure of initial cationic liposomes. Cryo-EM structural analysis demonstrates that multilamellar cationic liposomes induce two distinct interlamellar spacings in cationic lipoplexes, emphasizing the significant impact of the liposome structures on the final structure of mRNA lipoplexes. Taken together, our results provide an intriguing insight into the relationship between lipid assembly structures and the biophysical characteristics of the resulting lipoplexes. These relationships may open the door for advancing lipid-based mRNA delivery systems through more streamlined manufacturing processes.

Cold atmospheric pressure plasma assisted rapid assembly of peptide-based structures: a molecular scaffold to form supramolecular architectures

The use of cold atmospheric pressure plasma (CAPP) technology in the production of peptide-based materials has shown great potential in modern technology. Herein, two aggregation-prone oligopeptides, GNNQQNY and KLVFFA, were subjected to CAPP treatment to form supramolecular assemblies/aggregates. Through peptide engineering and biophysical techniques, the effect of CAPP-generated reactive oxygen and nitrogen species on the oligopeptides were investigated for different treatment times revealing that the formation of these aggregates were primarily driven by electrostatic interactions without any chemical modifications. Field emission-scanning electron microscopy and Thioflavin T (ThT) binding assay confirmed the presence of distinct β-strands, particularly in the aggregates of the KLVFFA peptide upon CAPP irradiation. The combination of CAPP technology with peptide self-assembly process and the characterization techniques employed in this study holds promise for the development of such peptide supramolecular structures based on the specific amino acid sequences.

Barium Concentration-Dependent Anomalous Electrophoresis of Synthetic DNA Motifs.

The structural integrity, assembly yield, and biostability of DNA nanostructures are influenced by the metal ions used to construct them. Although high (>10 mM) concentrations of divalent ions are often preferred for assembling DNA nanostructures, the range of ion concentrations and the composition of the assembly products vary for different assembly conditions. Here, we examined the unique ability of Ba2+ to retard double crossover DNA motifs by forming a low mobility species, whose mobility on the gel is determined by the concentration ratio of DNA and Ba2+. The formation of this electrophoretically retarded species is promoted by divalent ions such as Mg2+, Ca2+, and Sr2+ when combined with Ba2+ but not on their own, while monovalent ions such as Na+, K+, and Li+ do not have any effect on this phenomenon. Our results highlight the complex interplay between the metal ions and DNA self-assembly and could inform the design of DNA nanostructures for applications that expose them to multiple ions at high concentrations.

Modal characteristics of blade-disk including rough interfaces and geometric deviations

The inaccurate prediction of vibrations in blade-disk structures leads to frequent occurrences of failures in rotating machinery, such as air-engines. Existing methods often empirically treat the contact parameters of interfaces as globally constant and rarely consider manufacturing and assembly deviations, resulting in a deviation of prediction models from reality. This work presents a model for complex assembly structures that includes non-uniform distributions of normal contact stiffness and tangential friction coefficients at rough interfaces, while also introducing experimentally measured geometric deviations to enhance alignment with real-world conditions. Taking fir-tree blade-disk structure as an example, the accuracy of the proposed method is comprehensively verified by four measurement experiments and one modal experiment. Subsequently, the combined influence of rough interfaces and three experimentally measured geometric deviations on the overall modal characteristics of blade-disk structure are investigated, and their influencing mechanisms are revealed. The results indicate that ignoring the interface roughness and geometric deviations may significantly affect the prediction accuracy of the modal characteristics. The proposed method has great potential in the field of predicting the modal characteristics for complex assembly structures and optimizing the design of their machining and assembly processes.

Steady-state crack propagation during DCB test with viscoelastic-viscoplastic interface – Correlation between rheological behavior and effect of crack propagation rate

Adhesively bonded joints are known to suffer from creep and relaxation phenomena due to the viscous nature of the adhesive. These effects are detrimental to the durability of structural joints as they can lead to progressive and slow crack propagation rate phenomena and possible delayed failure. Master curve approaches are often used to assess the durability of structural assemblies, but the physical justification for such approaches requires additional investigation to more accurately assess the coupling between structural effects and the possible complex long-term rheological behaviour of the adhesive layer. Following similar approaches developed to study the steady-state crack propagation regime in bulk materials, an Eulerian description of crack propagation along a viscous adhesive layer during a double cantilever beam test is implemented. Taking into account viscoelastic-viscoplastic and various hardening rules, some master curves can be obtained describing the evolution of the crack propagation rate as a function of the stationary loading conditions. With such a model, the role of adhesive layer behaviour and joint geometry on crack propagation conditions can be discussed, as well as the applicability of such a master curve approach.

Uncovering the Molecular Composition and Architecture of the Bacillus subtilis Biofilm via Solid-State NMR Spectroscopy.

The complex and dynamic compositions of biofilms, along with their sophisticated structural assembly mechanisms, endow them with exceptional capabilities to thrive in diverse conditions that are typically unfavorable for individual cells. Characterizing biofilms in their native state is significantly challenging due to their intrinsic complexities and the limited availability of noninvasive techniques. Here, we utilized solid-state nuclear magnetic resonance (NMR) spectroscopy to analyze Bacillus subtilis biofilms in-depth. Our data uncover a dynamically distinct organization within the biofilm: a dominant, hydrophilic, and mobile framework interspersed with minor, rigid cores of limited water accessibility. In these heterogeneous rigid cores, the major components are largely self-assembled. TasA fibers, the most robust elements, further provide a degree of mechanical support for the cell aggregates and some lipid vesicles. Notably, rigid cell aggregates can persist even without the major extracellular polymeric substance (EPS) polymers, although this leads to slight variations in their rigidity and water accessibility. Exopolysaccharides are exclusively present in the mobile domain, playing a pivotal role in its water retention property. Specifically, all water molecules are tightly bound within the biofilm matrix. These findings reveal a dual-layered defensive strategy within the biofilm: a diffusion barrier through limited water mobility in the mobile phase and a physical barrier posed by limited water accessibility in the rigid phase. Complementing these discoveries, our comprehensive, in situ compositional analysis is not only essential for delineating the sophisticated biofilm architecture but also reveals the presence of alternative genetic mechanisms for synthesizing exopolysaccharides beyond the known pathway.

Effect of isopropyl chloride addition in AlCl3 catalytic system on the formation of coal tar pitch-based mesophases

Mesophase pitch is a high-quality precursor for the synthesis of high-performance pitch-based carbon fibers. The mesophase content, texture and softening point are the most important factors for the structure, properties and spinnability of mesophase pitch (MP). Herein, we report a novel approach for the preparation of mesophase pitch with high anisotropic content and low softening point by AlCl3 catalytic pyrolysis in the presence of isopropyl chloride (PrCl). The variation of anisotropic content and mesophase texture under different PrCl additions and the effect of the introduction of isopropyl on the molecular stacking of aromatic lamellar molecules were investigated. The results confirmed that, except for their role in improving catalytic activity, carbocation co-catalysts can improve the structure and molecular assembly of aromatic molecules through the introduction of alkyl groups. The reaction of isopropyl chloride (PrCl) as a co-catalyst catalyzed pyrolysis of medium-temperature coal pitch at 370 ℃ for 8 h produced a bulk mesophase with a content close to 100 %. Compared to the AlCl3 system (without PrCl), the AlCl3-PrCl system can catalyze the preparation of mesophases at lower temperatures. In addition, it is logical that the introduction of isopropyl group significantly increases the stacking spacing of the mesophase pitch layer molecules, which can effectively improve the mobility of the aromatic layer molecules resulting in the growth of mesophase. The fusion texture and anisotropic content of mesophase pitch were significantly improved by replacing the nucleophilic reagent of the AlCl3-catalyzed system. This work provides feasible ideas for the preparation of high-performance coal tar based mesophase pitch.

Structural behavior of fully prefabricated glubam-concrete composite beams constructed of innovative connectors

This study focuses on developing fully prefabricated glued laminated bamboo (glubam)-concrete composite (BCC) beams constructed of the innovative ultra-high performance concrete (UHPC)-steel composite connectors. Five mid-scale prefabricated BCC beams with different connectors and concrete slabs were tested under short-term loading conditions to evaluate the flexural behavior. Particular emphasis was placed on verifying the convenience and deconstructablity of the proposed assembly structure through a secondary assembly and loading process, revealing that the prefabricated BCC has the advantage of rapid assembly construction and appreciable reusability. This assembly structure exhibits favorable bending performance under short-term loading conditions and it shows partial composite action. Reducing spacing and enhancing shear resistance of the UHPC-steel composite connector effectively improves the flexural behavior of BCC beams. In addition, casting a layer of laminated lightweight aggregate concrete with 30 mm thick on site can enhance the bending performance of the prefabricated BCC beam with effective control of the increase in its self-weight. Typical load capacity models derived from timber-concrete composite (TCC) beam were evaluated by the test results for predicting the load capacity of the prefabricated BCC structure. A comparison and evaluation were conducted on six large-scale BCC beams connected by different connectors, indicating that the proposed fully prefabricated BCC system possesses superior competitive advantages compared with existing BCC/TCC beams and it has a good application prospect in building engineering.

Sequence planning for on-orbit robotic assembly based on symbiotic organisms search with diversification strategy

The demands for efficiency and stability in space missions have necessitated the development of sequence planning schemes for on-orbit robotic assembly of space structures. A sequence planning method is proposed in this work based on robotic kinematic analysis and Symbiotic Organisms Search (SOS) algorithm with a diversification strategy. With feasibility as the constraint and assembly cost as the objective function, the assembly sequence planning is regarded as an optimization problem. The assembly relationship constraint is depicted as the dependency between assembly steps represented by a directed acyclic graph. An abstract modeling method based on robotic kinematics is proposed to construct geometric feasibility constraint, accommodating the interference stemming from the multi-degree-of-freedom motion of the robotic system. A diversification strategy is exploited to address the issue of local optima arising from solving the optimal sequence based on SOS. A cost prediction method using previously calculated populations as samples is proposed to reduce the reliance on robotic dynamic analysis for cost calculation. Finally, simulations are carried out to validate the practicability of the proposed method.

Optimizing alkali metal Salt-Induced structural assembly of Ni-MgO dual function materials for enhanced CO2 capture and methanation performance

Alkali metal salts (AMS) promoted Ni-MgO dual function materials (DFMs) show exhibit potential in integrated CO2 capture and methanation. However, the CO2 adsorption and methanation efficiency of these materials is contingent upon their adsorptive and catalytic sites, which are significantly susceptible to the incorporated AMS. Herein, we investigate the effect of assemble configuration of AMS and Ni on the structural properties and integrated CO2 capture and methanation performance of the AMS-promoted Ni-MgO DFMs. By preferentially incorporating AMS to form the Ni-AMS-MgO configuration, AMS is allocated throughout both the internal core and external layer of MgO particles. Given AMS's preferential occupation of specific pore structures, Ni is evenly distributed as smaller particles on the MgO surface, minimally influenced by the carbonate formed during adsorption. The Ni-AMS-MgO configuration demonstrates superior integrated CO2 capture and methanation performance, featuring high CO2 uptake (1.86 mmol/g) and CH4 yield (1.37 mmol/g).

Emerging Trends of Nanofibrous Piezoelectric and Triboelectric Applications: Mechanisms, Electroactive Materials, and Designed Architectures.

Over the past few decades, significant progress in piezo-/triboelectric nanogenerators (PTEGs) has led to the development of cutting-edge wearable technologies. Nanofibers with good designability, controllable morphologies, large specific areas, and unique physicochemical properties provide a promising platform for PTEGs for various advanced applications. However, the further development of nanofiber-based PTEGs is limited by technical difficulties, ranging from materials design to device integration. Herein, the current developments in PTEGs based on electrospun nanofibers are systematically reviewed. This review begins with the mechanisms of PTEGs and the advantages of nanofibers and nanodevices, including high breathability, waterproofness, scalability, and thermal-moisture comfort. In terms of materials and structural design, novel electroactive nanofibers and structure assemblies based on 1D micro/nanostructures, 2D bionic structures, and 3D multilayered structures are discussed. Subsequently, nanofibrous PTEGs in applications such as energy harvesters, personalized medicine, personal protective equipment, and human-machine interactions are summarized. Nanofiber-based PTEGs still face many challenges such as energy efficiency, material durability, device stability, and device integration. Finally, the research gap between research and practical applications of PTEGs is discussed, and emerging trends are proposed, providing some ideas for the development of intelligent wearables.

Regioselective super-assembly of Prussian blue analogue

The construction of high-asymmetrical structures demonstrates significant potential in improving the functionality and distinctness of nanomaterials, but remains a considerable challenge. Herein, we develop a one-pot method to fabricate regioselective super-assembly of Prussian blue analogue (PBA) —— a PBA anisotropic structure (PBA-AS) decorated with epitaxial modules——using a step-by-step epitaxial growth on a rapidly self-assembled cubic substrate guided by thiocyanuric acid (TCA) molecules. The epitaxial growth units manifest as diverse geometric shapes, which are predominantly concentrated on the {100}, {111}, or {100}+{111} crystal plane of the cubic substrate. The crystal plane and morphology of epitaxial module can be regulated by changing the TCA concentration and reaction temperature, enabling a high level of controllability over specific assembly sites and structures. To illustrate the advantage of the asymmetrical structure, phosphated PBA-AS demonstrates improved performance in the oxygen evolution reaction compared to simple phosphated PBA nanocube. This method offers valuable insights for designing asymmetrical nanomaterials with intricate architectures and versatile functionalities.

Effect of elastic deformation on the heat transfer characteristic of refrigerator gasket based on static analysis of structural assemblies

ABSTRACT Soft and hard contact deformation is most common issue of the refrigerator gasket and it has almost been ignored in previous studies. In this paper, the novelty is to propose a thermal-solid coupling simulation to study the effect of assembly states on the heat transfer of gaskets, improving the accuracy of heat transfer simulation analysis. The numerical results indicate that the calculated temperature based on physical model of assembly state is closer to measured temperature. The assembly distance affects the assembly state of the gasket by changing the contact positions and lengths of contact interfaces. As a result, the heat transfer path and condition at the gasket region also changes. As the deformation increases form −1.0 mm to 5.0 mm, the heat leakage load of gasket rises firstly and then falls, in the range of 1.61 ~ 3.33 W•m−1. The heat leakage at the transfer paths of internal cold air, outer shell and cold bridge accounts for over 20%. Thus, it is recommended to reduce the contact interface length of internal cold air, increase the thermal resistance of auxiliary air-bag, reduce the thermal conductivity and thickness of magnetic strip and increase the contact thermal resistance of cold bridge.

Precision of Measurements of Delayed Slip in Structural High-Strength Assemblies by Contact and Optical Methods

Structural bolted connections of steel plates must fulfill the requirements specified by the standard EN 1090-2:2018 in the European Union. For the slip-resistant joints, the standard establishes the experimental procedure to obtain the delayed slip under a constant loading, which should not exceed 2 μm from the first five minutes to three hours. However, the usual extensometers available in laboratories, like LVDTs, lack the necessary precision to obtain a reliable measurement of such a small displacement because, even if their resolution is 1 μm, the scatter of repeated measurements of the same distance is normally higher. In contrast, the resolution and precision in optical methods like Digital Image Correlation (DIC) can be easily set under 1 μm depending on the number of pixels covering the studied area and the performed subpixel interpolation. This work introduces the use of DIC for delayed slip tests. In comparison with an LVDT, it is verified that this technique is a valid alternative to measure displacements at that scale with a simpler experimental setup.

Bottom-Up Synthesized Glucan Materials: Opportunities from Applied Biocatalysis.

Linear d-glucans are natural polysaccharides of simple chemical structure. They are comprised of d-glucosyl units linked by a single type of glycosidic bond. Noncovalent interactions within, and between, the d-glucan chains give rise to a broad variety of macromolecular nanostructures that can assemble into crystalline-organized materials of tunable morphology. Structure design and functionalization of d-glucans for diverse material applications largely relies on top-down processing and chemical derivatization of naturally derived starting materials. The top-down approach encounters critical limitations in efficiency, selectivity, and flexibility. Bottom-up approaches of d-glucan synthesis offer different, and often more precise, ways of polymer structure control and provide means of functional diversification widely inaccessible to top-down routes of polysaccharide material processing. Here the natural and engineered enzymes (glycosyltransferases, glycoside hydrolases and phosphorylases, glycosynthases) for d-glucan polymerization are described and the use of applied biocatalysis for the bottom-up assembly of specific d-glucan structures is shown. Advanced material applications of the resulting polymeric products are further shown and their important role in the development of sustainable macromolecular materials in a bio-based circular economy is discussed.

Glycosylated Antibiotics: New Promising Bacterial Efflux Pumps Inhibitors

Antimicrobial resistance is considered a major concern problem; bacteria have evolved mechanisms to overcome antibiotics’ action through evolutionary process. One main resistance mechanism that bacteria developed is the pumping of the antibiotics out of bacterial cells by transmembrane transporter proteins known as efflux pumps. To overcome bacterial resistance guided by efflux pumps, efflux pumps inhibitors (EPIs) are small molecules that obstruct efflux pumps binding sites and its structural assembly leading to disability in the efflux pumps normal function, new EPIs which under the current study are created by modifying the chemical structure of most common antibiotics including Ampicillin, Penicillin, Chloramphenicol, Ciprofloxacin and Tetracycline, such antibiotics are modified by adding N-acetyl glucose amine moiety to acceptor OH group of the respective antibiotic, the newly modified antibiotics are glycosylated EPIs. To test the effectiveness of the new EPIs in inhibiting AcrB-TolC and MexA-OprM efflux pumps functions, ADME properties for all of glycosylated antibiotics have been measured through applying Lipinski’s role of 5, docking and simulation studies have been included as well. Docked glycosylated tetracycline has given the highest binding energy in the active sites of both pumps, with -9.4 against AcrB and -8.8 against MexA. The simulation study has confirmed the binding of the glycosylated tetracycline in the active sites of both pumps, as well as its stability during the biological dynamicity of both pumps (opening and closing channels). The results validation requires a long simulation time about 50 ns or more which was un applicable due to cost limitation, however, the newly glycosylated antibiotics have promising results that might make it eligible as drug candidates to overcome bacterial resistance.

Hierarchical and reconfigurable interfibrous interface of bioinspired Bouligand structure enabled by moderate orderliness.

Introducing natural Bouligand structure into synthetics is expected to develop high-performance structural materials. Interfibrous interface is critical to load transfer, and mechanical functionality of bioinspired Bouligand structure yet receives little attention. Here, we propose one kind of hierarchical and reconfigurable interfibrous interface based on moderate orderliness to mechanically reinforce bioinspired Bouligand structure. The interface imparted by moderate alignment of adaptable networked nanofibers hierarchically includes nanofiber interlocking and hydrogen-bonding (HB) network bridging, being expected to facilitate load transfer and structural stability through dynamic adjustment in terms of nanofiber sliding and HB breaking-reforming. As one demonstration, the hierarchical and reconfigurable interfibrous interface is constructed based on moderate alignment of networked bacterial cellulose nanofibers. We show that the resultant bioinspired Bouligand structural material exhibits unusual strengthening and toughening mechanisms dominated by interface-microstructure multiscale coupling. The proposed interfibrous interface enabled by moderate orderliness would provide mechanical insight into the assembly of widely existing networked nanofiber building blocks toward high-performance macroscopic bioinspired structural assemblies.