Monolithic Structure Research Articles

Structure-property relationships of 3D woven fabric composites: A critical review through bibliometric and content analyses

3D fabric composites generally have significant thickness in a monolithic structure eliminating the need for multi-ply laminates. 3D fabric preforms have given significant boost to the composite industry by reducing one of the major failure modes, i.e., delamination. In the past few decades, an enormous amount of researches has been conducted in the domain of 3D woven fabric composites highlighting their structure-property relationships. There are 459 research articles related to 3D fabric composites in Scopus-indexed journals. The objective of this review is to summarise the extant literature, highlighting the current research trends, thematic research areas, structure-property relationships, and future research directions of 3D fabric composites. This review amalgamates bibliometric and content analyses to identify the dominant research themes within the 3D woven composite area. Content analysis of the research papers has revealed that the properties of 3D fabric composites depend on structural parameters such as weave design, binding step, binding depth, and stuffer-to-binder ratio. However, the results of these studies on the role of structural parameters are often divergent, implying that there is a need for more systematic research on the structure-property relationships of 3D fabric composites.

User-Centered Design of Architectural Models Adapted to Monolithic Structure Technology

Monolithic Structure Technology (MST) is a new construction process patented in Morocco, offering significant advantages in terms of durability, resilience, and energy efficiency. This technology enables the mass production of low-rise green buildings thanks to the design of a monolithic metal formwork with a high reuse rate for the bonding of the structure working mainly in compression. Unlike conventional approaches to construction, the architectural design and load-bearing structure are studied simultaneously from the formwork design phase, as the structure mobilizes its form to guarantee stability. The design of architectural models adapted to MST is therefore of paramount importance if we are to exploit the full potential of this innovative technology. In this context, we developed the most suitable designs for MST based on a user-centered approach by directly involving the presumed future operators through a structured questionnaire to identify their preferences.115 respondents were interviewed, and the results were analyzed and used to design 10 different models. We then complemented the design process with a neuro-architectural approach to optimize design factors (facades, levels and rooms, shape and openings, roof type, interior layout, green spaces, and materials). The 10 designed models were then used for a closed card sorting study, followed by another semi-structured interview. User preferences were synthesized and the optimum design for the Moroccan countryside was selected.

Microstructure and mechanical properties of MoNbVTa0.5Alx refractory high entropy alloys

The specific strength of refractory high entropy alloys (RHEAs) is usually impaired due to the high density of constituent elements. In order to develop a low-density RHEA, the microstructure and mechanical property of MoNbVTa0.5-based RHEAs with various Al additions have been investigated in this study. All samples exhibited a monolithic BCC solid solution structure. The addition of Al resulted in improved yield strength but a degraded plasticity at ambient temperature. In contrast, the yield strength consistently decreased with increasing Al content at elevated temperatures, and the softening occurred at ~1000 °C. MoNbVTa0.5Al0.3 exhibited high specific strengths of 119.2 MPa cm3/g, 108.6 MPa cm3/g and 97.3 MPa cm3/g at 600 °C, 800 °C, and 1000 °C, respectively.

A piezoelectric driven amphibious microrobot capable of fast and controllable movement

Abstract Due to its excellent adaptability to the environment and flexibility in narrow spaces, amphibious microrobots have become an important research direction recently. This study proposes an amphibious microrobot driven by piezoelectric actuators with a body length of 4.5 cm and a mass of 1.4 g. The microrobot consists of two active front legs, two passive rear legs, two caudal fins, and a support frame. Each front leg and each caudal fin are designed as structures integrated with their respective piezoelectric actuators. The microrobot has a tilted body, and the ground exerts an oblique upward impact force that makes it jump forward when its front legs swing backwards. The opposite swing of the two caudal fins generates propulsion for swimming. The components of the microrobot are manufactured based on the monolithic laminate process. The monolithic front actuator-leg and monolithic actuator-fin both emerge from a multi-layer material laminate. The support frame is designed and fabricated as a monolithic structure to improve assembly accuracy and reduce redundant assembly steps. The manufactured microrobot demonstrates its flexible and fast amphibious movements. Its maximum land walking speed reaches 15.3 cm/s and its turning speed reaches 48.2 degrees per second. The microrobot has a maximum payload capacity of 5 g moving on land. When the front legs and caudal fins work simultaneously, its underwater swimming speed reaches 9.1 cm/s, and the maximum turning speed is 20.5 degrees per second. The microrobot also confirms a maximum payload of 3 g during its underwater movement.

Additively Manufactured Structures for Precise and Robust Mounting of Optical Elements

The design freedom of Additive Manufacturing offers new opportunities for the design of mounting structures of optical systems, which are not feasible for conventional manufacturing approaches, thus opening up new areas of application for optical systems. We use this to develop a fully monolithic mounting structure for precise positioning of the optical elements, while simultaneously increasing their robustness against harsh environmental conditions. We additively manufacture such a mounting structure for an imaging lens and evaluate its optical performance with interferometric measurement of its wavefront, before and after applying a mechanical shock to the entire system. The results indicate a centering accuracy better than 6~µm, both in the initial positioning as well as the subsequent repositioning after a mechanical shock of 15G.

Basil seed mucilage as a bioadhesive polymer: Development of naproxen sodium microspheres and suppositories with in-vitro and ex-vivo studies

Background and purpose: The study explores basil seed mucilage as a bioadhesive carrier for naproxen sodium, demonstrating its ability to enhance solubility when administered rectally. The mucilage, derived from Ocimum basilicum seeds, showed bioadhesive properties and thermal stability, as confirmed by FTIR spectroscopy and X-ray diffraction analysis. Experimental approach: Microspheres were prepared using a double emulsion solvent evaporation technique, varying polymer ratios to optimize drug delivery. Key results: Particle size analysis revealed a range of 456±0.51 to 712±0.21 µm, with larger microspheres formed at higher mucilage concentrations due to increased viscosity. Encapsulation efficiency ranged from 45.01±0.25 % to 79.4±0.93 %, improving with higher basil/alginate ratios. The superior batch, OBM5, showed excellent mucoadhesive qualities in ex-vivo assays, attributed to the increased polymer content, facilitating interaction with rectal mucosa. SEM analysis of OBM5 indicated a spherical, monolithic structure conducive to free flow. Drug release was efficient, with OBM5 achieving 88.7±1.3 % after 7 hours, indicating a control­led release profile. Conclusion: Incorporated into polyethylene glycol (PEG) 4000 suppositories, suppose­tories were completely disintegrated in buffer solution within 25 minutes. The bioadhesive force of basil seed mucilage on rectal mucosa was significantly enhanced, reaching 6.44±0.58 g, correlating with mucilage concentration. These findings underscore the efficacy of basil seed mucilage as a bioadhesive biopolymer for rectal drug delivery systems.

Study of the Nature of the Destruction of Coatings Based on the ZrN System Deposited on a Titanium Alloy Substrate

The fracture strength was compared in a scratch test of coatings based on the ZrN system with the introduction of Ti, Nb and Hf, which were deposited on a titanium alloy substrate. The coatings were deposited using Controlled Accelerated Arc (CAA-PVD) technology. In coatings that simultaneously include Zr and Ti, a nanolayer structure is formed, while in coatings without Ti, the formation of a monolithic single-layer structure is observed. The comparison was carried out according to two parameters: adhesion strength to the substrate and overall coating strength. The (Zr,Hf)N coating showed better resistance to destruction, but had worse adhesion to the substrate. As a result, although the coating is retained directly in the scribing groove, a large area of delamination and destruction is formed around the groove. The (Ti,Zr,Nb)N coating, with its somewhat lower strength, has a high adhesion to the substrate; no noticeable delamination is observed along the groove boundary. In this paper, not only is the fracture resistance of various coatings deposited on a titanium alloy substrate compared, but the nature of this fracture is also investigated depending on the composition of the coatings.

Leveraging AWS and Java Microservices: An Analysis of Amazon\'s Scalable E-commerce Architecture

Abstract: This article presents a comprehensive case study of Amazon's journey in building a robust and scalable e-commerce platform capable of handling millions of daily transactions while maintaining high availability and performance. We examine the critical architectural decisions that facilitated Amazon's transition from a monolithic structure to a microservices-based architecture, leveraging Java and various AWS cloud services. The article explores key components of Amazon's scalable infrastructure, including the implementation of DynamoDB for high-performance database needs and the use of Elastic Load Balancing to ensure fault tolerance. We analyze the challenges encountered during this transformation and the solutions developed to address them. The article also discusses the resulting improvements in scalability, reliability, and cost-efficiency that have contributed to Amazon's position as the world's largest online retailer. Our findings provide valuable insights into best practices for architecting large-scale, cloud-native e-commerce platforms and offer implications for future developments in the field of distributed systems and cloud computing

Theoretical design and synthesis of Co30Ni60/CC for high selective methanol oxidation assisted energy-saving hydrogen production

The integration of methanol oxidation reaction (MOR) with hydrogen evolution reaction (HER) represents an advanced approach to hydrogen production technology. Nonetheless, the rational design and synthesis of bifunctional catalysts for both MOR and HER with exceptional activity, stability and selectivity present formidable challenges. In this work, firstly, density functional theory (DFT) was utilized to design and evaluate material models with high performance for both MOR and HER. Secondly, guided by DFT, Co30Ni60/CC (CC, carbon cloth) composites with a leaf-like nanosheet structure were successfully fabricated via electrodeposition. In the MOR process, Ni acts as the predominant active center, while Co amplifies the electrochemically active surface area (ECSA) and enhances the selectivity of methanol oxidation. Conversely, in the HER process, Co serves as the primary active center, with Ni augmenting the charge transfer rate. The electrochemical results demonstrate that Co30Ni60/CC exhibits exceptional performance in both MOR and HER at a current density (j) of 10 mA cm−2, with peak potentials of 1.323 V and −95 mV, respectively. Additionally, it shows remarkable selectivity for the oxidiation of methanol to high value-added formic acid. Thirdly, following a 100 h chronopotentiometry (CP) test, the required potential demonstrates an increase of 4.9 % (MOR) and 8.1 % (HER), signifying the superior stability of Co30Ni60/CC compared to those reported in the literature. The exceptional performance of Co30Ni60/CC can be primarily attributed to that the leaf-like nanosheets structure not only exposes a plethora of active sites but also facilitates electrolyte diffusion, the monolithic structure prepared by electrodeposition enhances its stability, and the transfer of electrons from Co to Ni regulates its electronic structure, as corroborated by X-ray photoelectron spectroscopy (XPS) and density of states (DOS) analyses. Finally, at the same j, the voltage required by the Co30Ni60/CC||Co30Ni60/CC electrolytic cell, powered by an electrochemical workstation, is 198 mV lower than that required for alkaline water-splitting. Meanwhile, at higher j (100 mA cm−2), the electrolytic cell exhibits sustained and stable operation for 150 h, enabling high-efficiency hydrogen production and the synthesis of high value-added formic acid.

Amine/vermiculite composite aerogels fabricated by polyethyleneimine-induced vermiculite nanosheet gelation for efficient direct air capture

Direct air capture (DAC), being able to remove the accumulated CO2 in atmosphere and CO2 carbon emission from discrete sources, is a promising technology for mitigating the global greenhouse effect and achieving carbon neutrality. However, achieving high-capacity, low-cost DAC of CO2 through simple methods remains a significant challenge. In this study, a simple, cost-effective, and environmentally friendly method for fabricating amine/vermiculite composite aerogels is proposed for capturing CO2 from ambient air. Natural two-dimensional material, vermiculite nanosheets with exposed surface and intrinsic negative charge, was utilized as the the building blocks for fabricating aerogel as solid amine adsorbents, via the fast gelatin between vermiculite and amine, significantly reducing the cost of adsorbent preparation while achieving promising CO2 capture capability. The effects of amine loading, amine molecular weight, and porosity on CO2 capture capacity and amine efficiency were investigated. It is found that the amine with larger molecular weights endows more stable amine anchoring in the composite aerogel, the aerogels using amine with higher molecular weights demonstrated higher residual amine ratios under vacuum conditions during the aerogel adsorbent synthesis, consequently enhancing the CO2 capture capacity of the adsorbents. By optimizing synthesis strategy and the amine loading of the composite aerogels, the highest CO2 capture capacity (0.72 mmol/g) and amine efficiency (0.29) were achieved. The monolithic structure of the aerogels ensures low pressure drop of 0.35 hPa during gas flow-through, enhancing their integration and applicability in adsorption devices. The vermiculite-based adsorbents exhibit unique advantages in practical DAC processes, including lower cost, higher amine efficiency, and stable cyclic performance. These findings hold significant promise for the application and advancement of DAC technologies.

Screen printed monolithic supercapacitor with talc and cellulose fiber separator

In this work, we demonstrate a fully screen printed supercapacitor (SC) with a monolithic structure. The monolithic SCs were prepared by screen printing different SC layers on top of each other. After the layers were printed, an aqueous electrolyte was added to the screen printed separator, and the printed structure was sealed. The prepared monolithic SCs showed similar electrical characteristics to a face-to-face laminated stacked SC with a paper separator. Interfaces between the screen printed SC layers were observed with a scanning electron microscope. Results show that the screen printing process is reproducible and can be used to fabricate SCs reliably. This fabrication process also eliminates an assembly step that is common in laminated stacked SCs. Hence the introduced screen printing process shows feasible and scalable fabrication for the monolithic SCs. Advanced fabrication of the printed monolithic SCs can benefit different applications, such as wireless sensor devices with environmentally sustainable energy storage units, and the integration of an energy storage unit on the same substrate with the printed circuits.

Real-Time Tunable Gas Sensing Platform Based on SnO2 Nanoparticles Activated by Blue Micro-Light-Emitting Diodes

HighlightsBlue micro-light-emitting diodes (μLED)-integrated gas sensors were fabricated as monolithic structure by directly loading sensing materials onto the μLED.SnO2 nanoparticles are activated by blue μLED and exhibit outstanding sensitivity to NO2 at μ-Watt power levels.Noble metal (Au, Pd, Pt)-decorated SnO2 showed the tunable gas selectivity for 4 target gases under blue light illumination.

Modeling Development of a Receiver–Reactor of Type R2Mx for Thermochemical Water Splitting

Abstract This work reports on the development of a transient heat transfer model for a prototype reactor of type R2Mx for thermochemical water splitting by temperature and pressure swing of ceria. Key aspects of the R2Mx concept, which are also incorporated in the prototype design, include a movable monolithic redox structure combined with a linear transport system, a reduction reactor, as well as a dedicated oxidation reactor. With the model, the operation of the prototype is simulated for consecutive water splitting cycles, in which ceria is reduced in a continuously heated reactor, oxidized in a separate oxidation reactor, and transported in between the reaction zones. A 2D axisymmetric numerical model of the prototype reactor was developed in ansys mechanical. The model includes heat transfer calculations in combination with an approximated simulation of the transport of the redox material during cyclic operation. It incorporates the chemical reaction by means of a modified heat capacity for ceria and accounts for internal radiation heat transfer inside the porous redox material by applying effective heat transfer properties. A parametric analysis has been undertaken to evaluate different modes of operation of the oxidation reactor. Model results are used to size the power demand of the reduction reactor and vacuum pump, to define durations of the process steps, as well as to assess operational parameters with respect to achieved temperatures. Findings suggest that suitable operation of the prototype reactor involves reduction durations ranging from 8 to 10 min and oxidations of 6 to 10 min.

Purification of his-tagged proteins using printed monolith adsorption columns

Bio-separation is a crucial process in biotechnology and biochemical engineering for separating biological macromolecules, and the field has long relied on bead-based and expanded bed chromatography. Printed monolith adsorption (PMA) is a new alternative to which uses a 3D-printed monolithic structure containing self-supporting, ordered flow channels. PMA allows for direct purification of biological molecules from crude cell lysates and cell cultures, and like the other technologies, can functionalized to specifically target a molecule and enable affinity chromatography. Here we have combined PMA technology with an immobilized metal affinity ligand (iminodiacetic acid) to provide selectivity of binding to polyhistidine-tagged proteins during PMA chromatography. Two different PMA structures were created and tested for both static and dynamic protein-binding capacity. At comparative linear flow rates, the dynamic binding capacity of both columns was ≈3 mg/mL, while static capacity was shown to differentiate based on column voidage. We show that a polyhistidine-tagged protein can be directly purified from crude lysate with comparable results to the available commercial providers of IMAC, and with a substantially reduced purification time.

Frequency conversion interposer with no-internal stress curved-beam for MEMS vibrational energy harvesters

The generating efficiency of an micro electro mechanical system vibrational energy harvester (MEMS VEH), which converts vibrational energy into electrical energy, is maximized at resonance. However, because the resonance frequency of an MEMS VEH is an order of magnitude higher than the vibrational frequency in the environment and not only has a high Q value, but the frequency of vibration in the environment changes randomly, it is difficult for MEMS VEHs to harvest vibrational energy efficiently. In this study, we propose a method to improve the generation efficiency of MEMS VEHs using a Frequency Conversion Interposer (FCI) that vibrates nonlinearly with its bistable no-internal stress curved-beam. As a simulation model combining FCI with the MEMS VEH, we fabricated a Two-Dimensional Monolithic Structure (TDMS) with a curved-beam and a straight beam that mimicked the FCI and oscillatory structure of the MEMS VEH, respectively. It was observed that the vibration of the straight beam induced snap-through (ST) of the curved-beam of the FCI, and the measured acceleration was more than 1.3 times the applied acceleration applied from the FCI to the MEMS VEH. As the power generation of the MEMS VEH is proportional to the square of the applied acceleration, the FCI is useful for improving the generating efficiency of the MEMS VEH.

Recent Advances in Regulating Ceramic Monolithic Catalyst Structure for Preferential Oxidation of CO in H2.

Preferential oxidation of CO (CO-PROX) has tremendous significance in purifying hydrogen for fuel cells to avoid catalyst poisoning by CO molecules. Traditional powder catalysts face numerous challenges, including high pressure drop, aggregation tendency, hotspot formation, poor mass and heat transfer efficiency, and inadequate thermal stability. Accordingly, ceramic monolithic catalysts, known as their excellent thermal stability, high surface area, and superior mass and heat transfer characteristics, are gaining increasing research attention. This review examines recent studies on ceramic monolithic catalysts in CO-PROX, placing emphasis on the regulation of active sites (e.g., precious metals like Pt and Au, and non-precious metals like CuO and CeO2), monolith structures, and coating strategies. In addition, the structure-catalytic performance relationships, as well as the potential and limitations of different ceramic monolithic catalysts in practical application, are discussed. Finally, the challenges of monolithic catalysts and future research prospects in CO-PROX reactions are highlighted.

DeltaFlex—An Additively Manufactured Delta Robot With Compliant Joints: Virtual Prototyping and Experimental Evaluation

Abstract The current study presents the development and validation of a compliant Delta robot with a monolithic structure, which has been fabricated using additive manufacturing (AM). The monolithic design and the use of AM accelerate the robot development cycle by enabling rapid prototyping and deployment while also facilitating experimentation with novel or different robot kinematics. The use of flexible joints for robots presents a challenge in achieving sufficient workspaces. However, parallel architectures are well suited for incorporating compliant joints, as they require lower ranges of motion for individual joints compared to serial architectures. Therefore, the Delta configuration has been chosen for this study. Multibody flexible dynamics (MfBD) simulations have been used as a means to guide design choices and simulate the structural behaviour of the robot. A design for additive manufacturing (DfAM) technique has been adopted to minimize the need for support structures and maximize mechanical strength. The quantitative evaluation of the Delta’s overall performance has been conducted in terms of stiffness and precision. The stiffness test aimed to gauge the robot’s ability to withstand applied loads, whereas the repeatability test assessed its precision and accuracy. This approach offers a promising path for robot design with significant potential for future advancements and practical applications while highlighting the trade-offs that designers should consider when adopting this methodology.

Structural stability of China’s asteroid mission target 2016 HO3 and its possible structure

ABSTRACT Asteroid 2016 HO$_3$, a small asteroid (<60 m) in super fast rotation state ($\sim$28 min), and is the target of China’s Tianwen-2 asteroid sample-return mission. In this work, we investigate its structural stability using an advanced soft-sphere-discrete-element-model code, dembody, which is integrated with bonded-aggregate models to simulate highly irregular boulders. The asteroid body is numerically constructed by tens of thousands particles, and then is slowly spun up until structural failure. Rubble piles with different frictions, cohesions, morphologies, grain size distributions, and structures are investigated. We find a 2016 HO$_3$ shaped granular asteroid would undergo tensile failure at higher strengths as opposed to shear failure in lower strengths, regardless of its shape and constituent grain size ratio. In the tensile failure regime, the critical tensile strength is proportional to the square of the spin rate, but surprisingly, is independent of the internal friction angle. Such relations indicate that the Maximum Tensile Stress criterion emerges as superior paradigm for investigating the failure behaviour of fast-rotating asteroids. We predict that the high-spin rate of asteroid 2016 HO$_3$ requires a surface strength over $\sim$3 Pa and a bulk tensile strength over $\sim$10–30 Pa. Through comparing these strength conditions with the latest data from asteroid missions, we suggest a higher likelihood of a monolithic structure over a typical rubble pile structure. However, the possibility of the latter cannot be completely ruled out. In addition, the asteroid’s surface could retain a loose regolith layer globally or only near its poles, which could be the target for sampling of Tianwen-2 mission.

Electronic Structure Regulation of MnCo2O4 via Surface‐Phosphorization Coupling to Monolithic Carbon for Oxygen Electrocatalysis in Zn–Air Batteries

AbstractAn urgent challenge to the development of rechargeable Zn–air batteries (RZABs) is the highly active, durable, and low‐cost catalysts for oxygen reduction reaction and oxygen evolution reaction (ORR and OER). Herein, a carbon‐based monolithic catalyst is designed via anchoring P‐modified MnCo2O4 inverse spinel nanoparticles on biomass‐derived carbon (P‐MnCo2O4@PWC). The introduction of surface P atoms regulates the electronic structures and valences of metal atoms by adjusting the coordination fields by (P‐O)δ– and Metal‐P. The optimization of the adsorption behavior of key intermediates facilitates the activation and conversion of reaction species. The monolithic structure is beneficial to the construction of a three‐phase interface for efficient mass transfer and high electrical conductivity. The P‐MnCo2O4@PWC catalyst displays outstanding bifunctional catalytic properties with a thin ΔE (the difference between the OER potential at 10 mA cm–2 and the ORR halfwave potential) of 0.66 V. The RZAB with P‐MnCo2O4@PWC as cathode delivers an exceptional peak power density (160 mW cm–2) and remarkable cycle life (over 1200 cycles), overcoming those with noble metal counterparts. This research provides a promising general surface‐phosphorization way to the design of carbon electrocatalysts and the high‐value utilization of biomass.

Development of a flow reactor incorporating polydopamine-poly(ε-caprolactone) with gold particles

Addressing the significant challenge of dye wastewater pollution, this study introduces a novel solution employing a flow catalytic reactor loaded with gold (Au) particles. The reactor utilizes a porous monolithic material with a Poly(ε-caprolactone) (PCL) matrix as the carrier for Au particles, with polydopamine employed to immobilize the Au onto the surface of the PCL monolith. To assess the catalytic efficiency of the reactor, a model catalytic degradation experiment involving the reaction between methyl orange (MO) and sodium borohydride was conducted. The catalytic reaction was facilitated by a peristaltic pump. The reactor setup involved fixing the monolith within a heat shrinkable tube, and the peristaltic pump ensured the flow catalytic reaction. The protective effect of liquid nitrogen was utilized to confirm that the porous structure of the PCL monolith, with its low melting point, remained intact after being fixed in the heat shrink tube. Catalytic results revealed remarkable efficacy, with the decomposition efficiency of MO reaching 98.54%. This flow reactor enables continuous operation, making it more practical for real-world applications compared to traditional batch methods. Furthermore, even after 5 cycles, the sample maintained a catalytic efficiency exceeding 90%, demonstrating the excellent reusability of the reactor.