Structural Engineering Approaches Research Articles

Cascading consequences of structural interventions in a tropical wandering gravel‐bed river

AbstractRiverscapes are often modified and managed through ‘command and control’ structural engineering approaches. These structures not only alter flow and sediment transport patterns but also negatively affect riverscape biodiversity. These impacts are particularly acute for rivers that are characterised by high mobility and wide flow distribution during extreme events. We used hydrodynamic and geomorphological change assessment to appraise the impacts of existing flood structures and their potential for removal in a tropical wandering gravel‐bed river in the Philippines. Our approach informs a systematic decision‐making process to screen opportunities for channel reconnection. Two‐dimensional hydraulic modelling showed flood structures confine flood water within the active channel for more frequent flood events, but banks are overtopped during larger magnitude events (>50‐year recurrence interval). Incorporating modelling results, a multi‐criteria analysis was developed to appraise opportunities for river reconnection based on structure purpose, functionality, and local land‐use. We differentiate among four actions for each structure: removal, redesign, set back, or retention. One structure is recommended for removal because it cuts off an anabranch, reduces channel capacity, and increases main anabranch bed shear stress. Increased potential for bed and bank erosion due to the structure's presence had a cascading effect, resulting in further interventions downstream and on the opposite bank. We show how the use of system‐scale two‐dimensional hydraulic modelling alongside high‐resolution topographic mapping can support management of interventions to reconnect a river to its wider anabranch‐bar morphology. Such actions form part of proactive, adaptive, and nature‐based flood management plans with local and non‐local benefits.

Three-layered nanoplates and amorphous/crystalline interface synergism boost CO2 photoreduction on bismuth oxychloride nanospheres.

Structural features like 3D nano-size, ultrathin thickness and amorphous/crystalline interfaces play crucial roles in regulating charge separation and active sites of photocatalysts. However, their co-occurrence in a single catalyst and exploitation in photocatalytic CO2 reduction (PCR) remains challenging. Herein, nano-sized bismuth oxychloride spheres (BiOCl-NS) confining three-layered nanoplates (∼2.2 nm ultrathin) and an amorphous/crystalline interface are exclusively developed via intrinsic engineering for an enhanced sacrificial-reagent-free PCR system. The results uncover a unique synergism wherein the three-layered nanoplates accelerate electron-hole separation, and the amorphous/crystalline interface exposes electron-localized active sites (Bi-Ovac-Bi). Consequently, BiOCl-NS exhibit efficient CO2 adsorption and activation with the lowering of rate-determining-step energy barriers, leading to remarkable CO production (102.72 μmol g-1 h-1) with high selectivity (>99%), stability (>30 h), and apparent quantum efficiency (0.51%), outperforming conventional counterparts. Our work provides a facile structural engineering approach for boosting PCR and offers distinct synergism for advancing diverse materials.

From Structure to Catalysis: Advances in Metal‐Organic Frameworks‐Based Shape‐Selective Reactions

AbstractThe presence of shape‐ and size‐selective catalysts in various catalytic reactions is of paramount importance. Metal‐organic frameworks (MOFs) possess a distinctive characteristic of lacking in‐accessible dead spaces, owing to their well‐structured nature. The effective separation of active sites within MOFs is facilitated by their exceptionally high surface area, which allows for a high density of active sites per unit volume of the catalyst. In this comprehensive review article, we delve into one of the most critical and practical features of MOFs: their ability to modify and engineer the structure of these materials. This structural engineering approach enables the attainment of desired physical, chemical, and surface properties, particularly in the realm of heterogeneous catalysts. The article encompasses several key areas, including surface functionalization within MOFs, synthesis of novel enzyme‐inspired MOFs, creation of mesoporous MOFs, development of porous structures utilizing MOFs, and engineering of structural limitations in MOFs. These rapidly advancing and highly applicable topics, especially in the field of heterogeneous catalysts, are thoroughly investigated and analyzed within the purview of this comprehensive review article.

N-year demand-to-capacity indexes and the design of high-rise buildings for wind

The purpose of this work is to assess the global load effects method, commonly used in current commercial practice for determining design wind effects on high-rise buildings. The assessment is performed by comparing results based on the global load effects method to their counterparts obtained by a conventional, well established structural engineering approach. That approach yields time series of the demand-to-capacity index (DCI) induced in structural members by time series of effective (aerodynamic + inertial) wind loads. The DCI time series so obtained depend upon member-specific influence coefficients, meaning that the time series of the DCIs, and therefore the peak DCIs and their times of occurrence, differ from member to member. In contrast, the global load effects method assumes that all the structural members’ peak DCIs occur at the same time, i.e., at the time of occurrence of the largest combination of base moments produced by the wind forces acting on the structure. The use of the global wind effects method in commercial practice is due to the fact that wind engineering laboratories do not have access to the structure’s influence coefficients. This work reports the novel finding that the global load effects method results in the underestimation of the DCIs of nearly all the members of the building’s structural system. Numerical examples are presented which show that the underestimation can be substantial. Therefore, the use of the global load effects method needs to be discontinued, and the estimation of the peak DCIs needs to be performed by accounting for their dependence upon the structure’s influence coefficients, a task that can only be performed by the structural engineering office.

Exploring structural engineering approach to formulate and characterize next-generation adjuvants.

It is critical to emphasize the importance of vaccination as it protects us against harmful pathogens. Despite significant progress in vaccine development, there is an ongoing need to develop vaccines that are not only safe but also highly effective in protecting against severe infections. Subunit vaccines are generally safe, but they frequently fail to elicit strong immune responses. As a result, there is a need to improve vaccine effectiveness by combining them with adjuvants, which have the potential to boost the immune system many folds. The process of developing these adjuvants requires searching for molecules capable of activating the immune system, combining these promising compounds with an antigen, and then testing this combination using animal models before approving it for clinical use. Liposomal adjuvants work as delivery adjuvants and its activity depends on certain parameters such as surface charge, vesicle size, surface modification and route of administration. Self-assembly property of peptide adjuvants and discovery of hybrid peptides have widened the scope of peptides in vaccine formulations. Since most pathogenic molecules are not peptide based, phage display technique allows for screening peptide mimics for such pathogens that have potential as adjuvants. This chapter discusses about peptide and liposome-based adjuvants focusing on their properties imparting adjuvanticity along with the methods of formulating them. Methods of adjuvant characterization important for an adjuvant to be approved for clinical trials are also discussed. These include assays for cytotoxicity, T-lymphocyte proliferation, dendritic cell maturation, cytokine and antibody production, toll-like receptor dependent signaling and adjuvant half-life.

Architectural engineering of MoS2/Fe2O3@carbon fiber heterostructures to obtain ultra-stable anodes for sodium-ion batteries

Metal sulfides based on a conversion mechanism possess high theoretical specific capacity, making them suitable for high-energy-density sodium-ion batteries (SIBs). However, they suffer from rapid capacity decay when assembled into full batteries due to dynamic hysteresis and large volume expansion. In this paper, the architectural engineering approach to construct MoS2/Fe2O3 @ carbon fiber heterostructures is proposed to overcome the above issues. The heterojunction formed by MoS2 and Fe2O3 would promote ion/electron transfer, while the carbon nano-fibers serve as a holder to maintain structural stability and ensure the rapid transport of electrons. The full battery in which the as-prepared MoS2/Fe2O3 @ carbon fiber anode is paired with a Na3V2(PO4)3/C cathode delivers a reversible capacity of 61.1 mAh g−1 at 500 mA g−1 for 1600 cycles without attenuation. Experimental characterization and theoretical calculation results show that this structural engineering approach improves the ion diffusion efficiency, enhances the conductivity, provides a more appropriate sodium ion adsorption energy, and thus extends the cycling life of the SIB. This work demonstrates the efficiency of architectural engineering and paves the way to design ultra-long-cycling Na-ion batteries.

Recent Trends in Transition Metal Phosphide (TMP)-Based Seawater Electrolysis for Hydrogen Evolution

Large-scale hydrogen (H2) production is an essential gear in the future bioeconomy. Hydrogen production through electrocatalytic seawater splitting is a crucial technique and has gained considerable attention. The direct seawater electrolysis technique has been designed to use seawater in place of highly purified water, which is essential for electrolysis, since seawater is widely available. This paper offers a structured approach by briefly describing the chemical processes, such as competitive chloride evolution, anodic oxygen evolution, and cathodic hydrogen evolution, that govern seawater electrocatalytic reactions. In this review, advanced technologies in transition metal phosphide-based seawater electrolysis catalysts are briefly discussed, including transition metal doping with phosphorus, the nanosheet structure of phosphides, and structural engineering approaches. Application progress, catalytic process efficiency, opportunities, and problems related to transition metal phosphides are also highlighted in detail. Collectively, this review is a comprehensive summary of the topic, focusing on the challenges and opportunities.

3D printed hierarchical interpenetrating phase composites with multi-scale mechanical energy absorption mechanisms

Lightweight, strong, and energy-absorbing materials are highly sought after in practical engineering applications. To this end, interpenetrating phase composites (IPC) stand as a novel class of composite materials to better leverage the properties of their constituents. Their structural design, however, has been limited to only specific structural features at a certain length scale in the existing studies. Inspired by the hierarchical composite materials in nature, this work proposes a novel concept of hierarchical interpenetrating phase composites (HIPC) by polymer infiltration into 3D printed hierarchical porous ceramic lattices. The hierarchical porous alumina lattices have up to three levels of porosity, including 3D printed macropores (≈300 μm), emulsion-templated micropores (≈10 μm), and sub-micropores (<1 μm) from partial sintering. Upon epoxy infiltration, three-level HIPC is constructed with hierarchically incorporated epoxy domains and alumina-epoxy interfaces, which leads to its unique multi-scale mechanical energy absorption mechanisms. Featuring a particularly porous and lightweight ceramic lattice, three-level HIPC exhibits an excellent combination of high specific compressive strength (64.6 kN m/kg), specific flexural strength (39.2 kN m/kg), and SEA (18.4 kJ/kg). In addition, even with a low ceramic content, three-level HIPC can effectively enhance the thermal conductivity via its hierarchically continuous ceramic microstructure. Therefore, our three-level HIPC has demonstrated impressive mechanical and thermal enhancement with its exquisite hierarchical architecture. The hierarchical structural engineering approach also represents a paradigm shift from constructing single-scale IPCs to multi-scale HIPCs and can be extended to other material combinations for high-performance structural and functional materials.

Designing continuous equilibrium structures that counteract gravity in any orientation

This paper presents a framework that can transform reconfigurable structures into systems with continuous equilibrium. The method involves adding optimized springs that counteract gravity to achieve a system with a nearly flat potential energy curve. The resulting structures can move or reconfigure effortlessly through their kinematic paths and remain stable in all configurations. Remarkably, our framework can design systems that maintain continuous equilibrium during reorientation, so that a system maintains a nearly flat potential energy curve even when it is rotated with respect to a global reference frame. This ability to reorient while maintaining continuous equilibrium greatly enhances the versatility of deployable and reconfigurable structures by ensuring they remain efficient and stable for use in different scenarios. We apply our framework to several planar four-bar linkages and explore how spring placement, spring types, and system kinematics affect the optimized potential energy curves. Next, we show the generality of our method with more complex linkage systems that carry external masses and with a three-dimensional origami-inspired deployable structure. Finally, we adopt a traditional structural engineering approach to give insight on practical issues related to the stiffness, reduced actuation forces, and locking of continuous equilibrium systems. Physical prototypes support the computational results and demonstrate the effectiveness of our method. The framework introduced in this work enables the stable, and efficient actuation of reconfigurable structures under gravity, regardless of their global orientation. These principles have the potential to revolutionize the design of robotic limbs, retractable roofs, furniture, consumer products, vehicle systems, and more.

Synergism of electronic structure regulation and interface engineering for boosting hydrogen evolution reaction on S-Scheme FeS2/S-ZnSnO3 heterostructure

The customization of the photocatalyst's composition and structure to achieve enhanced hydrogen (H2) evolution performance is still a major challenge. Herein, FeS2/S-ZnSnO3 (FeS2@S-ZSO) heterostructure was constructed for efficient photocatalytic hydrogen evolution reaction (HER) activity. The band structure of ZnSnO3 was regulated by sulfur doping (S-ZSO), followed by coupling with FeS2 nanoparticles to form a composite enabling improved optical absorption range and efficient spatial separation/transfer of photogenerated carriers. The HER performance of the optimal heterostructure (8.7%FeS2@S15%-ZSO) achieved 2225 μmol g-1 h-1, which was 14.4, 5 and 12.6 times greater than ZSO, S15%-ZSO and FeS2, respectively. DFT-based calculations further validated that S doping regulates the electronic structure of S-ZSO, while the coupling of FeS2 constructs a S-Scheme heterostructure, which accelerates the carrier separation and transport dynamics resulting in the improvement of the HER performance. This study presents a novel approach to improve the photocatalytic HER performance of wide bandgap semiconductors through electronic structural regulation and interface engineering approaches.

Perspective on computational design of two-dimensional materials with robust multiferroic coupling

Two-dimensional (2D) multiferroic materials with robust magnetoelectric coupling and controllable topological solitons (such as skyrmions) are promising candidates for advanced information storage and processing. Due to the limitations of experimental techniques, first-principles investigations stand out in answering fundamental questions of 2D multiferroic couplings, thus providing guidance for experimental validation. Herein, we will give a review of recent theoretical progress in the exploration of 2D multiferroic coupling via structural design and molecular engineering approach. Particularly, we will focus on (i) how to design the multiferroic structure in the 2D form; (ii) how to achieve robust magnetoelectric coupling; and (iii) how to electrically control the magnetic skyrmion via multiferroic effects. Finally, we give some perspectives on the remaining challenges and opportunities for predicting 2D multiferroic materials.

Gaussian Process Regression for Seismic Fragility Assessment: Application to Non-Engineered Residential Buildings in Indonesia

Indonesia is located in a high-seismic-risk region with a significant number of non-engineered houses, which typically have a higher risk during earthquakes. Due to the wide variety of differences even among parameters within one building typology, it is difficult to capture the total risk of the population, as the typical structural engineering approach to understanding fragility involves tedious numerical modeling of individual buildings—which is computationally costly for a large population of buildings. This study uses a statistical learning technique based on Gaussian Process Regression (GPR) to build the family of fragility curves. The current research takes the column height and side length as the input variables, in which a linear analysis is used to calculate the failure probability. The GPR is then utilized to predict the fragility curve and the probability of collapse, given the data evaluated at the finite set of experimental design. The result shows that GPR can predict the fragility curve and the probability of collapse well, efficiently allowing rapid estimation of the population fragility curve and an individual prediction for a single building configuration. Most importantly, GPR also provides the uncertainty band associated with the prediction of the fragility curve, which is crucial information for real-world analysis.

The Role of Life Cycle Structural Engineering in the Transition towards a Sustainable Building Renovation: Available Tools and Research Needs

Given the current climate emergency and the ambitious targets of carbon emissions reduction, retrofitting strategies on existing buildings typically include reducing energy demand, decarbonising the power supply, and addressing embodied carbon stored in materials. This latter point redefines the role of engineers in the transitions towards a sustainable construction sector, being they responsible for designing low impact, sustainable and carbon neutral solutions. A Life Cycle Structural Engineering (LCSE) approach, inspired by the principles of Life Cycle Thinking (LCT), should thus be adopted for the sustainable renovation of existing buildings. Only recently have pioneering approaches been proposed, tackling multifaceted buildings’ needs, such as those related to energy consumption as well as seismic safety, but often disregarding LCT principles. This study presents a redefinition of the concept of LCSE for sustainable construction and a comprehensive review of available methods and tools to operationalise the LCSE approach in practice, focusing on the consideration of LCT principles in the retrofitting design process, integration of seismic loss estimation and environmental impact assessment, and implementation of integrated retrofitting strategies. The greatest ambition of this work is thus to boost a paradigm shift for building engineers towards an interdisciplinary perspective in building assessment and retrofitting.

Structural Engineering Approach for Designing Foil-Based Flexible Capacitive Pressure Sensors

Structural engineering plays an essential role in designing, improving, and optimizing an electromechanical system, instinctively affecting its performance. In this study, design optimization, finite element analysis, and experimental evaluation of capacitive pressure sensors were conducted. The air pressure sensing application was demonstrated to characterize different sensors, which include a combination of multiple rectangular cantilevers and diaphragms (square and circular-shaped). After the design improvement, we found that the square and circular diaphragms each with two trapezoidal cantilevers exhibited highest sensitivity to air pressure monitoring among the different investigated designs which combine the square and circular diaphragms with cantilevers. These designs were then selected for further analysis for acoustic pressure monitoring. The sensors were fabricated using the do-it-yourself technique with household materials such as post-it paper, posted tape, and foil. Our approach offers an alternative to the conventional cleanroom fabrication technique and uses easily available materials to fabricate affordable sensors. Therefore, this is the first step toward the development of democratized and sustainable electronic devices that are affordable and available to everyone on the internet.

Structural and Computational Studies of the SARS-CoV-2 Spike Protein Binding Mechanisms with Nanobodies: From Structure and Dynamics to Avidity-Driven Nanobody Engineering.

Nanobodies provide important advantages over traditional antibodies, including their smaller size and robust biochemical properties such as high thermal stability, high solubility, and the ability to be bioengineered into novel multivalent, multi-specific, and high-affinity molecules, making them a class of emerging powerful therapies against SARS-CoV-2. Recent research efforts on the design, protein engineering, and structure-functional characterization of nanobodies and their binding with SARS-CoV-2 S proteins reflected a growing realization that nanobody combinations can exploit distinct binding epitopes and leverage the intrinsic plasticity of the conformational landscape for the SARS-CoV-2 S protein to produce efficient neutralizing and mutation resistant characteristics. Structural and computational studies have also been instrumental in quantifying the structure, dynamics, and energetics of the SARS-CoV-2 spike protein binding with nanobodies. In this review, a comprehensive analysis of the current structural, biophysical, and computational biology investigations of SARS-CoV-2 S proteins and their complexes with distinct classes of nanobodies targeting different binding sites is presented. The analysis of computational studies is supplemented by an in-depth examination of mutational scanning simulations and identification of binding energy hotspots for distinct nanobody classes. The review is focused on the analysis of mechanisms underlying synergistic binding of multivalent nanobodies that can be superior to single nanobodies and conventional nanobody cocktails in combating escape mutations by effectively leveraging binding avidity and allosteric cooperativity. We discuss how structural insights and protein engineering approaches together with computational biology tools can aid in the rational design of synergistic combinations that exhibit superior binding and neutralization characteristics owing to avidity-mediated mechanisms.

A universal post-treatment strategy for biomimetic composite hydrogel with anisotropic topological structure and wide range of adjustable mechanical properties

The development of biomimetic materials with anisotropic topological structure and wide range of adjustable mechanical properties is central to tissue engineering fields. In this work, on the basis of a stiff/stretchable dually crosslinked hydrogel, we paid more attention to the synergistic contribution of the confined drying and re-swelling (CDR) effect and Hofmeister effect to its micro structures, polymer aggregation states and mechanical strength. Specifically, by changing the pre-strains of the CDR procedure and the soaking time during the salting-out procedure, the arrangement structure orientation, chain-entanglement density, and supramolecular interaction strength within the polymer can be adjusted by changing the processing sequence of the two procedures, so that to obtain anisotropic biomimetic hydrogels with adjustable mechanical properties in a wide range. Thus, this engineered anisotropic polymer can mimic the natural tissues’ mechanical properties in regeneration. Moreover and importantly, these anisotropic hydrogels exhibit prominent self-recovery properties. In summary, with the integration of molecular and structural engineering approaches, this study presents a universal strategy for developing anisotropic hydrogels, which could be widely used as biomimetic substitutes with anisotropic features in tissue regeneration.

Hierarchically Interlaced 2D Copper Iodide/MXene Composite for High Thermoelectric Performance

A hierarchical layered architecture in thermoelectric materials works as an ad hoc methodology for strengthening the unique inherent properties. Herein, an excellent thermoelectric behavior in novel 2D copper iodide nanoflakes is demonstrated by compositing with Ti3C2 MXene nanoinclusions. The interlaced architecture of the CuI/Ti3C2 composite lifts the electrical conductivity over two orders by efficient charge transport mechanisms. The thermal conductivity of CuI/Ti3C2 composite is reduced by drastic suppression of mid‐ and high‐frequency phonons by interfacial energy barrier scattering. The structural engineering approach yields a massive power factor of 225 μW m−1 K−2 and a figure of merit value of 0.48 in CuI/5 vol% Ti3C2 composite. A straightforward approach of tuning the figure of merit in Earth‐abundant, nontoxic thermoelectric materials to develop future sustainable energy sources is established.

Electrochemical CO2 Reduction on Cu: Synthesis-Controlled Structure Preference and Selectivity.

The electrochemical CO2 reduction reaction (ECO2RR) on Cu catalysts affords high‐value‐added products and is therefore of great practical significance. The outcome and kinetics of ECO2RR remain insufficient, requiring essentially the optimized structure design for the employed Cu catalyst, and also the fine synthesis controls. Herein, synthesis‐controlled structure preferences and the modulation of intermediate's interactions are considered to provide synthesis‐related insights on the design of Cu catalysts for selective ECO2RR. First, the origin of ECO2RR intermediate‐dominated selectivity is described. Advanced structural engineering approaches, involving alloy/compound formation, doping/defect introduction, and the use of specific crystal facets/amorphization, heterostructures, single‐atom catalysts, surface modification, and nano‐/microstructures, are then reviewed. In particular, these structural engineering approaches are discussed in association with diversified synthesis controls, and the modulation of intermediate generation, adsorption, reaction, and additional effects. The results pertaining to synthetic methodology‐controlled structural preferences and the correspondingly motivated selectivity are further summarized. Finally, the current opportunities and challenges of Cu catalyst fabrication for highly selective ECO2RR are discussed.

Silos structural response to blast loading

Extensive research work has been conducted to study the structural behavior of silos for various static load types; namely the grain load compression phases inside the silos and the thermal loads. However, very few investigations were related to the effect of different dynamic loads on silos, especially shock and blast loads. The aim of this research is to evaluate the structural response of grain silos due to massive blast loads. The Beirut explosion that occurred on August 04, 2020 is considered as a case study in a structural engineering approach with numerical non-linear finite element modeling of the silos. Due to the uncertainty of the exploded material mass, the magnitude of the explosion is defined as the numerical model magnitude that generates the same silos damages and sways recorded on site. The numerical study models are based on silos data (geometrical and material properties), and the use of the Conventional Weapons Effects Blast Loading (CONWEP), and the Coupled Eulerian-Lagrangian (CEL) methods to generate the blast loads. In addition, damage for the standing silos has been assessed, and final recommendations were stated. The results of this study define the magnitude of the explosion and the structural state of the remaining silos.

Microtrench‐Patterned Elastomeric Substrate for Stretchable Electronics with Minimal Interference by Bodily Motion

AbstractChallenges associated with local stress concentration on layers in stretchable devices under mechanical deformation by bodily motions, which causes strain‐induced signal interference and generates cracks, constitute one of the remaining issues for realization of skin‐attachable stretchable electronics. Herein, a new structural engineering approach is introduced for an elastomeric substrate, a microtrench‐patterned stretchable substrate, in which microtrenches are formed on the substrate backside, effectively mitigating local stress on the surface layers under stretching. Combining the microtrench pattern on the backside and 3D stress‐absorbing microstructured surface on the frontside of the elastomeric substrate for stress engineering results in effective suppression of stress concentration on the crack‐prone carbon paste electrode and piezoresistive pressure sensing layer on the frontside surface due to stress‐concentration on microtrench pattern and, in turn, minimal change in their resistance with deformation. This approach using a simple and facile method to minimize stress in device layers under motion‐induced deformation has great potential for applications of diverse materials for body‐attachable stretchable electronics with minimal strain‐responsiveness.