Hasil untuk "Structural engineering (General)"

Junfeng Xie, Jiajia Zhang, Shuang Li et al.

C. Farrar, K. Worden

Zhoutong Sun, Qian Liu, G. Qu et al.

The term B-factor, sometimes called the Debye-Waller factor, temperature factor, or atomic displacement parameter, is used in protein crystallography to describe the attenuation of X-ray or neutron scattering caused by thermal motion. This review begins with analyses of early protein studies which suggested that B-factors, available from the Protein Data Bank, can be used to identify the flexibility of atoms, side chains, or even whole regions. This requires a technique for obtaining normalized B-factors. Since then the exploitation of B-factors has been extensively elaborated and applied in a variety of studies with quite different goals, all having in common the identification and interpretation of rigidity, flexibility, and/or internal motion which are crucial in enzymes and in proteins in general. Importantly, this review includes a discussion of limitations and possible pitfalls when using B-factors. A second research area, which likewise exploits B-factors, is also reviewed, namely, the development of the so-called B-FIT-directed evolution method for increasing the thermostability of enzymes as catalysts in organic chemistry and biotechnology. In both research areas, a maximum of structural and mechanistic insights is gained when B-factor analyses are combined with other experimental and computational techniques.

Geng Wu, Xiao Han, Jinyan Cai et al.

Strain has been shown to modulate the electronic structure of noble metal nanomaterials and alter their catalytic performances. Since strain is spatially dependent, it is challenging to expose the active strained interfaces by structural engineering with atomic precision. Herein, we report a facile method to manipulate the planar strain in ultrathin noble metal nanosheets by constructing amorphous–crystalline phase boundaries that can expose the active strained interfaces. Geometric-phase analysis and electron diffraction profile demonstrate the in-plane amorphous–crystalline boundaries can induce about 4% surface tensile strain in the nanosheets. The strained Ir nanosheets display substantially enhanced intrinsic activity toward the hydrogen evolution reaction electrocatalysis with a turnover frequency value 4.5-fold higher than the benchmark Pt/C catalyst. Density functional theory calculations verify that the tensile strain optimizes the d-band states and hydrogen adsorption properties of the strained Ir nanosheets to improve catalysis. Furthermore, the in-plane strain engineering method is demonstrated to be a general approach to boost the hydrogen evolution performance of Ru and Rh nanosheets. While inducing strain to noble metal nanomaterials can modulate catalytic activities, the strain is often spatially dependent. Here, authors manipulate the planar strain in noble metal nanosheets for hydrogen evolution electrocatalysis by constructing amorphous–crystalline phase boundaries.

Adibah Zamhuri, G. Lim, N. Ma et al.

MXene is a recently emerged multifaceted two-dimensional (2D) material that is made up of surface-modified carbide, providing its flexibility and variable composition. They consist of layers of early transition metals (M), interleaved with n layers of carbon or nitrogen (denoted as X) and terminated with surface functional groups (denoted as T x /T z ) with a general formula of M n+1 X n T x , where n  = 1–3. In general, MXenes possess an exclusive combination of properties, which include, high electrical conductivity, good mechanical stability, and excellent optical properties. MXenes also exhibit good biological properties, with high surface area for drug loading/delivery, good hydrophilicity for biocompatibility, and other electronic-related properties for computed tomography (CT) scans and magnetic resonance imaging (MRI). Due to the attractive physicochemical and biocompatibility properties, the novel 2D materials have enticed an uprising research interest for application in biomedicine and biotechnology. Although some potential applications of MXenes in biomedicine have been explored recently, the types of MXene applied in the perspective of biomedical engineering and biomedicine are limited to a few, titanium carbide and tantalum carbide families of MXenes. This review paper aims to provide an overview of the structural organization of MXenes, different top-down and bottom-up approaches for synthesis of MXenes, whether they are fluorine-based or fluorine-free etching methods to produce biocompatible MXenes. MXenes can be further modified to enhance the biodegradability and reduce the cytotoxicity of the material for biosensing, cancer theranostics, drug delivery and bio-imaging applications. The antimicrobial activity of MXene and the mechanism of MXenes in damaging the cell membrane were also discussed. Some challenges for in vivo applications, pitfalls, and future outlooks for the deployment of MXene in biomedical devices were demystified. Overall, this review puts into perspective the current advancements and prospects of MXenes in realizing this 2D nanomaterial as a versatile biological tool.

Miao Yu, Lida Zhu, Zhichao Yang et al.

Artificial intelligence provides novel perspectives for laser metal additive manufacturing (LMAM), enhancing precision, efficiency, and structural and process optimization. Machine learning-assisted process–structure–property correlation in additive manufacturing (ML-PSP-AM) presents an effective pathway for structural innovation and performance optimization, leveraging automation and intelligence to address the growing processing demands across industries. This review differs from the existing literature by presenting a multi-scale, PSP-centered analysis of ML applications in LMAM, integrating discussions that span from processing-driven macro-scale formation to meso/micro-scale defect prediction and microstructure–property relationships. By evaluating state-of-the-art ML applications across various AM stages, we identify current limitations, propose targeted strategies, and outline opportunities to improve accuracy, minimize defects, and enhance mechanical properties such as strength and fatigue life. The advancement of ML-assisted AM should focus on breakthroughs from “0 to 1” in application and innovations from “1 to ∞” in algorithms. The realization of ML-PSP-AM represents a transformative yet disruptive integration of manufacturing engineering, artificial intelligence, and materials science, driving significant progress in modern manufacturing technologies.

K. Yuen

Debiao Meng, S. Yang, C. He et al.

PurposeAs an advanced calculation methodology, reliability-based multidisciplinary design optimization (RBMDO) has been widely acknowledged for the design problems of modern complex engineering systems, not only because of the accurate evaluation of the impact of uncertain factors but also the relatively good balance between economy and safety of performance. However, with the increasing complexity of engineering technology, the proposed RBMDO method gradually cannot effectively solve the higher nonlinear coupled multidisciplinary uncertainty design optimization problems, which limits the engineering application of RBMDO. Many valuable works have been done in the RBMDO field in recent decades to tackle the above challenges. This study is to review these studies systematically, highlight the research opportunities and challenges, and attempt to guide future research efforts.Design/methodology/approachThis study presents a comprehensive review of the RBMDO theory, mainly including the reliability analysis methods of different uncertainties and the decoupling strategies of RBMDO.FindingsFirst, the multidisciplinary design optimization (MDO) preliminaries are given. The basic MDO concepts and the corresponding mathematical formulas are illustrated. Then, the procedures of three RBMDO methods with different reliability analysis strategies are introduced in detail. These RBMDO methods were proposed for the design optimization problems under different uncertainty types. Furtherly, an optimization problem for a certain operating condition of a turbine runner blade is introduced to illustrate the engineering application of the above method. Finally, three aspects of future challenges for RBMDO, namely, time-varying uncertainty analysis; high-precision surrogate models, and verification, validation and accreditation (VVA) for the model, are discussed followed by the conclusion.Originality/valueThe scope of this study is to introduce the RBMDO theory systematically. Three commonly used RBMDO-SORA methods are reviewed comprehensively, including the methods' general procedures and mathematical models.

Ali Shirzad, Seyed Ali Asghar Hosseini, Hamidi Amir

In present study, the response of a cemented granular and horizontal layer is investigated under one-dimensional harmonic vibrations applied at its base. The modeling was performed considering an infinite horizontal layer with displacements occurred in one direction with uniform shear stress and strain distributions on horizontal planes. It is considered that only shear displacements occur when the soil layer is subjected to seismic excitation at base. The nonlinear behavior due to cyclic loading can be determined using dynamic characteristics of soil like shear modulus and damping ratio. These dynamic characteristics are dependent to different parameters like confining pressure and cement content. In present study, an empirical model was applied for determination of dynamic characteristics of cemented and uncemented soil. By deriving the one degree of freedom equation of motion, an approximate solution was suggested using perturbation method. Finally, the resonance phenomenon was studied for cemented granular layer and the amplitudes were predicted with a precise approximation. Based on the results, the suggested method was able to predict the response of soil layer with good consistency comparing to the results of numerical methods like Runge-Kutta.

Hariharan Surendran, Punitha Kumar Akhas

Amidst rising natural aggregate consumption, recycling dumped waste for structural concrete effectively addresses resource scarcity and environmental contamination. Nevertheless, the adoption of toughened glass waste aggregate (TGWA) in construction remains relatively limited. This study explores the potential use of toughened glass waste (TGW) as a substitute for natural coarse aggregate (NCA) in high-performance concrete (HPC). This paper assesses the bond strength of deformed bars embedded in toughened glass waste high-performance concrete (TGW-HPC), considering different steel reinforcement diameters (8 mm and 12 mm) and various levels of TGW replacement (ranging from 0 % to 100 %). Various durability properties, including water absorption, water permeability, chloride ion penetration, and acid attack were examined. The study also investigated the microstructural characteristics of acid attacked specimens using techniques such as XRD, FTIR, and FESEM. Several important parameters, such as chloride diffusivity (D), hydraulic diffusivity (D (θ)), and permeability coefficients (K), were derived from the experimental data. The study found TGW50-HPC resulted in the highest bond strength, about 13.1 % more than the control mix. However, TGW100-HPC bond strength decreased by 17.51 % compared to the control mix. Notably, TGW100-HPC exhibited superior durability properties and showed the lowest coefficient of permeability, indicating reduced chloride ion, and water molecule transport through the interconnected pore structure. At 90 days, the TGW100-HPC mixture exhibited a strength reduction of 42.29 %, which closely resembled the 41.20 % reduction observed at 56 days. The formation of thenardite and basanite mitigate damage to the interfacial transition zone (ITZ) led to fewer micro-cracks and reduced acid ingress through the matrix. Incorporating TGWA in engineering projects can lead to cost savings through reduced raw material expenses and disposal fees, resulting in significant economic benefits and social well-being.

Gajalakshmi G, Meenakshi S

This paper explores the intricate relationship between man and nature in Ernest Hemingway’s The Old Man and the Sea through the lens of deep ecology. It challenges the traditional anthropocentric interpretation of the novella, proposing that the protagonist Santiago’s struggle is not merely a tale of human triumph over nature but a journey towards understanding and coexisting with the natural world. By applying the principles of deep ecology, the study reveals how Santiago’s evolving relationship with the marlin and other sea elements reflects a broader ecological consciousness. The analysis also draws parallels between Santiago’s experience and the Biblical narrative of Jonah, suggesting that Santiago’s success is not solely due to his physical endurance but also the cosmic forces that aid him. This paper ultimately rethinks the themes of struggle and victory in the novella, emphasising the need for a harmonious relationship between humanity and the environment.

Dejene Tadesse Banjaw, Habtamu Gudisa Megersa

Garlic is a versatile vegetable commonly grown in subtropical and highland agroecosystems, which is utilized for its culinary, medicinal, and spice properties. The use of garlic as a medicinal aid can be traced back to ancient times. The health benefits of garlic production are attributed to its antiviral, antibacterial, and antifungal properties. The use of garlic is prevalent in both traditional and modern healthcare systems, where it is used to treat a wide range of conditions. Numerous studies have reported the therapeutic properties of garlic, and its effectiveness has been demonstrated in clinical trials. The growing global interest in health and wellness, the widespread use of garlic as a spice, and its potential economic, social, and health benefits have contributed to a surge in its demand worldwide. This review aims to provide a comprehensive overview of the scientific literature on the morphological descriptions of garlic and its nutritional and health significance.

Cuizheng Zhang, Jiemin Zhao, Brandon Lu et al.

Sequence-selective recognition of DNA duplexes is important for a wide range of applications including regulating gene expression, drug development, and genome editing. Many small molecules can bind DNA duplexes with sequence selectivity. It remains as a challenge how to reliably and conveniently obtain the detailed structural information on DNA-molecule interactions because such information is critically needed for understanding the underlying rules of DNA-molecule interactions. If those rules were understood, we could design molecules to recognize DNA duplexes with a sequence preference and intervene in related biological processes, such as disease treatment. Here, we have demonstrated that DNA crystal engineering is a potential solution. A molecule-binding DNA sequence is engineered to self-assemble into highly ordered DNA crystals. An X-ray crystallographic study of molecule-DNA cocrystals reveals the structural details on how the molecule interacts with the DNA duplex. In this approach, the DNA will serve two functions: (1) being part of the molecule to be studied and (2) forming the crystal lattice. It is conceivable that this method will be a general method for studying drug/peptide-DNA interactions. The resulting DNA crystals may also find use as separation matrices, as hosts for catalysts, and as media for material storage.

E. Cross, T. Rogers, D. Pitchforth et al.

Abstract Despite the growing availability of sensing and data in general, we remain unable to fully characterize many in-service engineering systems and structures from a purely data-driven approach. The vast data and resources available to capture human activity are unmatched in our engineered world, and, even in cases where data could be referred to as “big,” they will rarely hold information across operational windows or life spans. This paper pursues the combination of machine learning technology and physics-based reasoning to enhance our ability to make predictive models with limited data. By explicitly linking the physics-based view of stochastic processes with a data-based regression approach, a derivation path for a spectrum of possible Gaussian process models is introduced and used to highlight how and where different levels of expert knowledge of a system is likely best exploited. Each of the models highlighted in the spectrum have been explored in different ways across communities; novel examples in a structural assessment context here demonstrate how these approaches can significantly reduce reliance on expensive data collection. The increased interpretability of the models shown is another important consideration and benefit in this context.

Sourav Dutta, M. Roy

Significant attention has been drawn in recent years to develop porous scaffolds for tissue engineering. In general, porous scaffolds are used for non-load bearing applications. However, various metallic scaffolds have been investigated extensively for hard tissue repair due to their favorable mechanical and biological properties. Stainless steel (316L) and titanium (Ti) alloys are the most commonly used material for metallic scaffolds. Although stainless steel and Ti alloys are employed as scaffold materials, it might result in complications such as stress shielding, local irritation, interference with radiography, etc. related to the permanent implants. To address the above-mentioned complications, degradable metallic scaffolds have emerged as a next generation material. Among the all metallic degradable scaffold materials, magnesium (Mg) based material has gained significant attention owing to its advantageous mechanical properties and excellent biocompatibility in a physiological environment. Therefore, Mg based materials can be projected as load bearing degradable scaffolds, which can provide structural support toward the defected hard tissue during the healing period. Moreover, advanced manufacturing techniques such as solvent cast 3D printing, negative salt pattern molding, laser perforation, and surface modifications can make Mg based scaffolds promising for hard tissue repair. In this article, we focus on the advanced fabrication techniques which can tune the porosity of the degradable Mg based scaffold favorably and improve its biocompatibility.

Lawrence Sawunyama, Opeyemi Oyewo, Damian C. Onwudiwe et al.

Fabrication of heterojunction and surface defective engineering, through the formation of oxygen vacancies, are among the various photocatalytic enhancement techniques. A combination of these techniques has the prospect of enhancing photocatalytic activities through improved light absorption capabilities and charge separation process of the photocatalysts. In this study, a heterojunction of black titanium oxide-zinc oxide (BTiO2–ZnO) nanocomposite was synthesized using the conventional sol-gel approach, coupled with aluminum foil-assisted NaBH4 reduction. The structure, morphology, surface properties, and optical characteristics of the synthesized material were studied using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV–vis absorption spectra, scanning electron microscope (SEM), Energy-dispersive X-ray spectroscopy (EDS), and transmission electron microscope (TEM). The XRD confirmed the successful formation of BTiO2–ZnO heterostructure, while SEM revealed the structural morphology as pseudo-spherical with slight agglomeration. BTiO2–ZnO was found to be more efficient than BTiO2 and BZnO for the removal of tetracycline with degradation efficiencies of 63, 58, and 56 % respectively. The effects of process parameters such as the amount of photocatalyst, pollutant's concentration, and the initial solution pH on photocatalytic degradation study were systematically explored. The results confirm that the formation of the heterostructure from BTiO2 and BZnO could offer a facile route to improving the catalytic degradation of tetracycline. Therefore, this study offers a novel perspective on the design of efficient metal oxide photocatalyst systems that rely on the integration of defect engineering and heterojunction for the removal of organic contaminants.

F. Ascione, L. Granata, L. Guadagno et al.

Abstract Adhesive durability and joint reliability, strictly related to the bonding agents, are key parameters still under evaluation in civil as well as in other engineering fields. Moisture, different environmental agents and temperature (in particular) can strongly affect the performance of the adhesive joints over the time limiting their applicability. The environmental temperature may exceed the glass transition temperature (Tg) of the adhesive formulation entailing relevant changes in its properties, determining, for instance, a transition from a hard to a rubbery behaviour, thus compromising its specific application. Furthermore, due to changes of the temperature values, the structural adhesive can be naturally subjected to a delay or increase in the curing degree. Hence adverse or positive changes in strength and stiffness can be manifested. Within this framework, the topic of the present paper is the study of the hygro-thermal durability of two commercial epoxy resins, suitable for civil engineering applications, respect to the immersion in tap water and sea water for a period of fifteen months at the temperature of 30°C. To this scope a wide experimental program was developed comprising both End Notch Failure (ENF) tests on the adhesive samples (adherent in glass fiber reinforced polymer, GFRP) for evaluating the pure fracture energy in Mode II of the resins and the water absorption tests for resins and GFRP materials. In general, the results, in terms of fracture energy, show an initial increment (first three-four months) followed by a decrement up to the reaching of a plateau (in the ninth-twelfth month of conditioning). For what concerns the water absorption, the results show that the equilibrium value of both resins is reached in about one month, while that of GFRP samples depend on the type of liquid: three months for tap water and about five months for sea water. Considering the lower activity of the seawater, the longer time to reach the equilibrium value was an expected result.

Daniel S. Yu, M. Outram, Ashley Smith et al.

Plant pathogens secrete proteins, known as effectors, that function in the apoplast or inside plant cells to promote virulence. Effector recognition by cell-surface or cytosolic receptors results in the activation of defence pathways and plant immunity. Despite their importance, our general understanding of fungal effector function and recognition by immunity receptors remains poor. One complication often associated with effectors is their high sequence diversity and lack of identifiable sequence motifs precluding prediction of structure or function. In recent years, several studies have demonstrated that fungal effectors can be grouped into structural classes, despite significant sequence variation and existence across taxonomic groups. Using protein x-ray crystallography, we identify a new structural class of effectors hidden within the secreted in xylem (SIX) effectors from Fusarium oxysporum f. sp. lycopersici (Fol). The recognised effectors Avr1 (SIX4) and Avr3 (SIX1) represent the founding members of the Fol dual-domain (FOLD) effector class, with members containing two distinct domains. Using AlphaFold2, we predicted the full SIX effector repertoire of Fol and show that SIX6 and SIX13 are also FOLD effectors, which we validated experimentally for SIX6. Based on structural prediction and comparisons, we show that FOLD effectors are present within three divisions of fungi and are expanded in pathogens and symbionts. Further structural comparisons demonstrate that Fol secretes effectors that adopt a limited number of structural folds during infection of tomato. This analysis also revealed a structural relationship between transcriptionally co-regulated effector pairs. We make use of the Avr1 structure to understand its recognition by the I receptor, which leads to disease resistance in tomato. This study represents an important advance in our understanding of Fol-tomato, and by extension plant-fungal interactions, which will assist the development of novel control and engineering strategies to combat plant pathogens.

Vesna Žegarac Leskovar, M. Premrov

Numerous countries across the globe have witnessed the recent decades’ trend of multi-storey timber buildings on the rise, owing to advances in engineering sciences and timber construction technologies. Despite the growth and numerous advantages of timber construction, the global scale of multi-storey timber construction is still relatively low compared to reinforced concrete and steel construction. One of the reasons for a lower share of high-rise timber buildings lies in the complexity of their design, where the architectural design, the selection of a suitable structural system, and the energy efficiency concept strongly depend on the specific features of the location, particularly climate conditions, wind exposure, and seismic hazard. The aforementioned shows the need for a comprehensive study on existing multi-storey timber buildings, which correspond to the boundary conditions in a certain environment, to determine the suitability of such a construction in view of its adjustment to local contexts. Apart from exposing the problems and advantages of such construction, the current paper provides a brief overview of high-rise timber buildings in Europe. Moreover, it addresses the complexity of the design approach to multi-storey timber buildings in general. The second part of the paper highlights the importance of synthesising the architectural, energy, and structural solutions through a detailed analysis of three selected case studies. The findings of the paper provide an expanded view of knowledge of the design of tall timber buildings, which can significantly contribute to a greater and better exploitation of the potential of timber construction in Europe and elsewhere.