Hasil untuk "Structural engineering (General)"

A. Bello, Deogil Kim, Dohyun Kim et al.

Health care and medicine were revolutionized in recent years by the development of biomaterials, such as stents, implants, personalized drug delivery systems, engineered grafts, cell sheets, and other transplantable materials. These materials not only support the growth of cells before transplantation but also serve as replacements for damaged tissues in vivo. Among the various biomaterials available, those made from natural biological sources such as extracellular proteins (collagen, fibronectin, laminin) have shown significant benefits, and thus are widely used. However, routine biomaterial-based research requires copious quantities of proteins and the use of pure and intact extracellular proteins could be highly cost ineffective. Gelatin is a molecular derivative of collagen obtained through the irreversible denaturation of collagen proteins. Gelatin shares a very close molecular structure and function with collagen and thus is often used in cell and tissue culture to replace collagen for biomaterial purposes. Recent technological advancements such as additive manufacturing, rapid prototyping, and three-dimensional printing, in general, have resulted in great strides toward the generation of functional gelatin-based materials for medical purposes. In this review, the structural and molecular similarities of gelatin to other extracellular matrix proteins are compared and analyzed. Current strategies for gelatin crosslinking and production are described and recent applications of gelatin-based biomaterials in cell culture and tissue regeneration are discussed. Finally, recent improvements in gelatin-based biomaterials for medical applications and future directions are elaborated. Impact statement In this study, we described gelatin's biochemical properties and compared its advantages and drawbacks over other extracellular matrix proteins and polymers used for biomaterial application. We also described how gelatin can be used with other polymers in creating gelatin composite materials that have enhanced mechanical properties, increased biocompatibility, and boosted bioactivity, maximizing its benefits for biomedical purposes. The article is relevant, as it discussed not only the chemistry of gelatin, but also listed the current techniques in gelatin/biomaterial manufacturing and described the most recent trends in gelatin-based biomaterials for biomedical applications.

Varun R. Shanker, Theodora U. J. Bruun, Brian L. Hie et al.

Large language models trained on sequence information alone can learn high-level principles of protein design. However, beyond sequence, the three-dimensional structures of proteins determine their specific function, activity, and evolvability. Here, we show that a general protein language model augmented with protein structure backbone coordinates can guide evolution for diverse proteins without the need to model individual functional tasks. We also demonstrate that ESM-IF1, which was only trained on single-chain structures, can be extended to engineer protein complexes. Using this approach, we screened about 30 variants of two therapeutic clinical antibodies used to treat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We achieved up to 25-fold improvement in neutralization and 37-fold improvement in affinity against antibody-escaped viral variants of concern BQ.1.1 and XBB.1.5, respectively. These findings highlight the advantage of integrating structural information to identify efficient protein evolution trajectories without requiring any task-specific training data. Editor’s summary Despite tremendous advances in protein structure prediction, connecting sequence to function is key for the in silico engineering of proteins for various tasks. Focusing on the problem of antibody engineering, Shanker et al. used a structure-informed protein language model to predict high-fitness sequences constrained by the known structure of the antibody or antibody-antigen complex. In experimental screens of virus-neutralizing antibodies, the authors observed substantial improvement in binding affinity and neutralization for their predicted sequences. These results demonstrate the potential for machine learning and protein language models trained on protein sequence information to contribute to protein engineering tasks even in the absence of task-specific training data. —Michael A. Funk

Menggang Li, F. Lin, Shipeng Zhang et al.

Alloying has proven power to upgrade metallic electrocatalysts, while the traditional alloys encounter limitation for optimizing electronic structures of surface metallic sites in a continuous manner. High-entropy alloys (HEAs) overcome this limitation by manageably tuning the adsorption/desorption energies of reaction intermediates. Recently, the marriage of nanotechnology and HEAs has made considerable progresses for renewable energy technologies, showing two important trends of size diminishment and multidimensionality. This review is dedicated to summarizing recent advances of HEAs that are rationally designed for energy electrocatalysis. We first explain the advantages of HEAs as electrocatalysts from three aspects: high entropy, nanometer, and multidimension. Then, several structural regulation methods are proposed to promote the electrocatalysis of HEAs, involving the thermodynamically nonequilibrium synthesis, regulating the (sub-)nanosize and anisotropic morphologies, as well as engineering the atomic ordering. The general relationship between the electronic structures and electrocatalytic properties of HEAs is further discussed. Finally, we outline remaining challenges of this field, aiming to inspire more sophisticated HEA-based nanocatalysts.

Raquel Schmitt Cavalheiro, Pedro Ignácio Lima Gadêlha Jardim, Antonio José Santos Junior et al.

Abstract The use of tropical wood species in the production of glued laminated timber (GLT) has been researched with the aim of facilitating the utilization of this material in countries lacking pine and eucalyptus. Teak (Tectona grandis) stands out as a wood species with superior physical and mechanical properties, in addition to exhibiting excellent natural durability. Studies indicate that the use of Teak in GLT is promising. Besides the wood properties, the interphase of the composite directly impacts structural performance, which is typically evaluated through macroscopic testing. However, incorporating microscopic analyses can provide valuable insights into bonding characteristics, which directly affect macroscopic results. Although many studies employ microscopy techniques such as polarized light microscopy (LM), fluorescence microscopy (FM), confocal laser scanning microscopy (CSLM), scanning electron microscopy (SEM), and micro-computed tomography (µCT), no studies have yet compared the effectiveness of these approaches. In this context, the present research aimed to compare the efficiency of five different microscopy techniques in assessing the adhesive interphase in GLT elements produced with Teak. It was observed that the evaluated techniques are complementary, each with specific advantages and limitations. The most detailed results were obtained with CSLM, indicating the relevance of this methodology for more precise analyses of adhesive interphases. In addition to conducting macroscopic tests, it is recommended to employ at least two complementary microscopy techniques to corroborate additional information regarding the quality of bonding in GLT beams. This approach can significantly contribute to the enhancement of GLT manufacturing and usage, reinforcing the effectiveness of Teak as a viable and sustainable alternative.

Hanadi Dheyaa LANKRANI, Ali Talib JASIM

The process of renovating flexible pavement produces an extensive amount of reclaimed asphalt pavement (RAP). These aggregates are frequently discarded, whether through legal or illegal means, in nearby locations, thereby creating various challenges for regulatory bodies. The incorporation of these aggregates into portland cement concrete (PCC) mixtures represents an innovative strategy that could yield significant socio-economic and environmental advantages. Nonetheless, the inclusion of RAP aggregates may also adversely impact both the soundness and performance characteristics of the concrete. This paper delivers a detailed and critical evaluation of the practicality of employing RAP aggregates in concrete production, while also pinpointing several shortcomings that must be rectified to enhance sustainability in construction methodologies. This paper is structured in the following manner: it initiates with a detailed characterization of RAP aggregates, followed by an analysis of the characteristics of fresh concrete containing RAP, and culminates in an exploration of RAP containing concrete mechanical and durability characteristics. According to the literature review, it is evident that aggregates derived from RAP are generally of a lower quality than their natural counterparts. This may not pose a significant issue regarding the characteristics of the fresh concrete. The asphalt film and the presence of agglomerated particles within the RAP were identified as key factors contributing to the diminished strength and durability characteristics. The integration of RAP as aggregates has been associated with notable advantages, including improved toughness. Furthermore, existing research suggests that the performance of concrete containing RAP can be enhanced through the processing of RAP in conjunction with using supplementary cementitious materials (SCMs) or fibres.

Ibrahim Behram Ugur, Ozkan Kizilay

In recent years, metaheuristic optimization methods have been widely applied across various engineering disciplines, offering effective solutions to complex problems that require both efficiency and reliability. Within this context, this study has two primary objectives. The first is to apply the Dandelion Optimizer (DO), inspired by the three-stage flight of dandelion seeds, to the optimum design of spatial steel frames and to evaluate its performance as a structural optimization algorithm. The second is to investigate the influence of different soil types, as defined in the Turkish Building Earthquake Code (TBEC-2018), on the optimum design outcomes. For this purpose, three benchmark spatial steel frames consisting of 132, 428, and 720 members were optimized using DO. The algorithm was implemented in MATLAB R2017b and integrated with SAP2000 v19 via the Open Application Programming Interface (OAPI). The design process was performed in accordance with TBEC-2018 and the AISC-LRFD, with strength, stability, and serviceability constraints considered. The results indicate that deteriorating soil conditions from ZA to ZE lead to substantial increases in structural demands. In the three analyzed models, total weight increases within the range of 45–57%, whereas total seismic base shear shows a much sharper rise, ranging from 160% to 292% These findings demonstrate both the practical applicability of the DO in steel frame optimization and the critical impact of soil conditions on structural design, underlining the importance of incorporating geotechnical factors into optimization frameworks.

Li J, Zhou T, Wang P et al.

Juan Li,1,* Ting Zhou,1,* Pei Wang,1,* Ruian Yin,1 Shengqi Zhang,1 Yile Cao,1 Lijuan Zong,1 Ming Xiao,2 Yongjie Zhang,3 Wentao Liu,4 Lingxiao Deng,5 Fei Huang,6 Jianfei Sun,7,* Hongxing Wang1,* 1Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China; 2Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, Nanjing, 211166, People’s Republic of China; 3Department of Human Anatomy, Nanjing Medical University, Nanjing, 211166, People’s Republic of China; 4Department of Pharmacology, Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, Nanjing, 211166, People’s Republic of China; 5Department of Neurological Surgery, Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indianapolis, IN, 46202-2266, USA; 6Institute of Neurobiology, Binzhou Medical University, Yantai, 264003, People’s Republic of China; 7State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory of Biomaterials and Devices, School of Biological Science and Medical Engineering, Southeast University, Nanjing, 210009, People’s Republic of China*These authors contributed equally to this workCorrespondence: Jianfei Sun, State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory of Biomaterials and Devices, School of Biological Science and Medical Engineering, Southeast University, Nanjing, 210009, People’s Republic of China, Email sunzaghi@seu.edu.cn Hongxing Wang, Department of Rehabilitation Medicine, Southeast University Zhongda Hospital, Nanjing, 210024, People’s Republic of China, Email 101012648@seu.edu.cnBackground: Gigantocellular reticular nucleus (GRNs) executes a vital role in locomotor recovery after spinal cord injury. However, due to its unique anatomical location deep within the brainstem, intervening in GRNs for spinal cord injury research is challenging. To address this problem, this study adopted an extracorporeal magnetic stimulation system to observe the effects of selective magnetic stimulation of GRNs with iron oxide nanoparticles combined treadmill training on locomotor recovery after spinal cord injury, and explored the possible mechanisms.Methods: Superparamagnetic iron oxide (SPIO) nanoparticles were stereotactically injected into bilateral GRNs of mice with moderate T10 spinal cord contusion. Eight-week selective magnetic stimulation produced by extracorporeal magnetic stimulation system (MSS) combined with treadmill training was adopted for the animals from one week after surgery. Locomotor function of mice was evaluated by the Basso Mouse Scale, Grid-walking test and Treadscan analysis. Brain MRI, anterograde virus tracer and immunofluorescence staining were applied to observe the tissue compatibility of SPIO in GRNs, trace GRNs’ projections and evaluate neurotransmitters’ expression in spinal cord respectively. Motor-evoked potentials and H reflex were collected for assessing the integrity of cortical spinal tract and the excitation of motor neurons in anterior horn.Results: (1) SPIO persisted in GRNs for a minimum of 24 weeks without inducing apoptosis of GRN cells, and degraded slowly over time. (2) MSS-enabled treadmill training dramatically improved locomotor performances of injured mice, and promoted cortico-reticulo-spinal circuit reorganization. (3) MSS-enabled treadmill training took superimposed roles through both activating GRNs to drive more projections of GRNs across lesion site and rebalancing neurotransmitters’ expression in anterior horn of lumbar spinal cord.Conclusion: These results indicate that selective MSS intervention of GRNs potentially serves as an innovative strategy to promote more spared fibers of GRNs across lesion site and rebalance neurotransmitters’ expression after spinal cord injury, paving the way for the structural remodeling of neural systems collaborating with exercise training, thus ultimately contributing to the reconstruction of cortico-reticulo-spinal circuit. Keywords: gigantocellular reticular nucleus, locomotion, magnetic stimulation, spinal cord injury, superparamagnetic iron oxide nanoparticles, treadmill training

Yangjinyu Li, Li Zou, Zhengjie Zhu

In order to reduce the S-N curve dispersion of titanium alloy welded joints and improve the prediction accuracy of fatigue life, a novel optimization method of S-N curve fitting based on neighborhood rough set reduction with improved firefly algorithm (IFANRSR) is proposed. Firstly, we propose an improved firefly algorithm (IFA) by updating the position and step size, combining IFA algorithm and neighborhood rough set into an IFANRSR algorithm for attribute reduction. Then, according to the fatigue data of titanium alloy welded joints, the fatigue decision system of welded joints is established, and the key factors affecting the fatigue life of welded joints are determined. Next, according to the set of key influencing factors obtained based on IFANRSR algorithm, the fatigue characteristics domains are divided, and the S-N curves are fitted on each fatigue characteristics domain, to obtain a group of S-N curves. To demonstrate the effectiveness of IFA algorithm, six benchmark functions are used, then the availability of IFANRSR algorithm is evaluated in comparison with other algorithms on four UCI datasets. Finally, the results of the goodness-of-fit show that the dispersion of fatigue data is reduced, which can effectively improve the prediction accuracy of fatigue life.

Mei Wu, Xiaowei Zhang, Xiaomei Li et al.

Flexoelectricity is a type of ubiquitous and prominent electromechanical coupling, pertaining to the electrical polarization response to mechanical strain gradients that is not restricted by the symmetry of materials. However, large elastic deformation is usually difficult to achieve in most solids, and the strain gradient at minuscule is challenging to control. Here, we exploit the exotic structural inhomogeneity of grain boundary to achieve a huge strain gradient (~1.2 nm−1) within 3–4-unit cells, and thus obtain atomic-scale flexoelectric polarization of up to ~38 μC cm−2 at a 24° LaAlO3 grain boundary. Accompanied by the generation of the nanoscale flexoelectricity, the electronic structures of grain boundaries also become different. Hence, the flexoelectric effect at grain boundaries is essential to understand the electrical activities of oxide ceramics. We further demonstrate that for different materials, altering the misorientation angles of grain boundaries enables tunable strain gradients at the atomic scale. The engineering of grain boundaries thus provides a general and feasible pathway to achieve tunable flexoelectricity. Large strain gradient is crucial for flexoelectricity. Here, the authors reveal the generality and tunability of large strain gradients at grain boundaries in oxides, explaining the possible effects on the electrical activities of ceramics.

Victoria Hwang, A. Stephenson, Solomon Barkley et al.

Significance Structural color comes from interference of light scattered from a nanostructure. Disordered nanostructures have structural colors that are independent of viewing angle, similar to dyed materials. Unlike dyes, structural colors resist fading and can be broadly tuned, making them useful for many applications. However, making a nanostructure with a given color is challenging because there are so many tunable parameters. Furthermore, applications such as cosmetics or displays require specific component materials. To solve this design problem, we develop a model that quantitatively predicts the color for given experimental parameters. We then use optimization to determine the parameters required to make a target color under specific constraints. This approach makes it possible to engineer structural color for many different applications. Disordered nanostructures with correlations on the scale of visible wavelengths can show angle-independent structural colors. These materials could replace dyes in some applications because the color is tunable and resists photobleaching. However, designing nanostructures with a prescribed color is difficult, especially when the application—cosmetics or displays, for example—requires specific component materials. A general approach to solving this constrained design problem is modeling and optimization: Using a model that predicts the color of a given system, one optimizes the model parameters under constraints to achieve a target color. For this approach to work, the model must make accurate predictions, which is challenging because disordered nanostructures have multiple scattering. To address this challenge, we develop a Monte Carlo model that simulates multiple scattering of light in disordered arrangements of spherical particles or voids. The model produces quantitative agreement with measurements when we account for roughness on the surface of the film, particle polydispersity, and wavelength-dependent absorption in the components. Unlike discrete numerical simulations, our model is parameterized in terms of experimental variables, simplifying the connection between simulation and fabrication. To demonstrate this approach, we reproduce the color of the male mountain bluebird (Sialia currucoides) in an experimental system, using prescribed components and a microstructure that is easy to fabricate. Finally, we use the model to find the limits of angle-independent structural colors for a given system. These results enable an engineering design approach to structural color for many different applications.

Olav U. Bjørken, Benjamin Andresen, Sindre W. Eikevåg et al.

The current limitations of design for additive manufacturing (DfAM) are the state of knowledge on materials and the effects of production parameters. As more engineering-grade polymers become available for fused filament fabrication (FFF), the designs and processes must be adapted to fully utilize the structural properties of such materials. By studying and comparing the production parameters of a material test specimen and a component, the effects of layer temperature on the strength, surface roughness, and dimensional accuracy of PA6-CF were found. As the cross-section increases in component manufacturing, maintaining the layer temperature becomes a major challenge. From the findings, the concept of thermal layer design (TLD) was introduced as a way of increasing strength via temperature in selected regions after presenting the effect of layer temperature. TLD proved to have a major effect on layer temperature and heat distribution. Depending on the investigated layer temperature, from 147 °C to 193 °C the UTS of PA6-CF increased from 42 MPa to 73 MPa. Implementing TLD in DfAM represents a big leap for designing high-performance polymer components.

Mustafa Aslan, Merve Dundar

Sur district in Diyarbakir city like all historical places in Mesopotamia is a city that has rich historical buildings. The urban transformation has become a necessity as a result of the historical process, unplanned construction, change of tools and equipment in transportation, environmental and ecological problems, and social activities. For this reason, urban transformation applications have been started in Sur. As a result of the transformation; the formerly irregular constructions and environment have become regular. Accordingly, many environmental problems have been reduced. In addition to this, due to the exchange in the originality of historical architecture, some negative have been experienced too.  In this study, positive and negative perspective effects of urban transformations on public living and the environment were examined. Situations before and after their transformations were compared and evaluated. The results show that urban transformations have a positive effect majority of environmental effects.

shahad ali, Ali J. Jaeel

Excessive use of nitrogen fertilizers has increased nitrate concentrations in groundwater, which poses a health hazard from nitrate-contaminated drinking water and contributes to eutrophication. Nitrate removal from water systems has been carefully studied; However, new, low-cost solutions are urgently needed. Clay and terracotta minerals are commonly used in environmental applications due to their non-toxicity, global availability, low cost, and physical and chemical properties (ion-exchange capacity, high surface area, high adsorption, and catalytic properties). Although most are used to reduce cationic pollutants, depending on the method of modification or the materials with which they are mixed, they can be equally effective in removing anionic contamination. The goal of the study is to treat water containing excessive concentrations of nitrates to produce water of acceptable environmental specifications and to evaluate the performance of fired clay as a low-cost and environmentally friendly water treatment material.

Raluca Nerisanu, Delia Dragan

This paper presents two examples for the solution of polyhedral surfaces intersection, of elliptical paraboloid respectively, by making use of the representation system of the projections with elevations.

E. Mohseni, Romina Saadati, Negar Kordbacheh et al.

Ying-Tung Lin, Tzu-wei Hung, L. Huang

M. Allen, D. Rixen, M. V. D. Seijs et al.

Xing Chen, L. Liang, Xinglian Xu

Abstract Background Meat-derived protein is an extraordinary nutrient. However, this gluten-free and keto-friendly protein has long been underutilized due to their limited functional roles. The application of high pressure homogenization (HPH) on modifying these precious sources for converting them into functional ingredient has attracted great interest. An updated summary on this area is of urgent to fill the knowledge gap in the exploitation of meat protein and processing benefits of HPH. Scope and approach This review started with a brief introduction on the definition, composition variation and functionality of meat protein. Principles of HPH modification and its operation engineering were also highlighted. Thereafter, the structural and functional changes of meat protein induced by HPH as well as their potential application were comprehensively discussed. Finally, the future research on meat protein modification by HPH and the related practical trier on the engineering aspect were prospected. Key findings and conclusions In general, HPH can dissociate meat proteins accompanied by partial unfolding of the subunit and exposing of reactive sites, meanwhile the re-aggregation of subunit promptly occurred, especially under harsh HPH conditions. These structural changes created by HPH led to modulation of their functionalities and thereby of their utilizations. HPH can enhance the functional properties of chicken breast myofibrillar protein in water for tailor-manufacturing nutritious beverages. HPH can valorize proteins from the meat wastes (the mechanical deboned chicken meat and collagen-rich tissue) and deliver superior surface-active properties to fish and shellfish proteins, thus allow them to be accessible for a broad application in foods.

P. Pedeferri

Yunpeng Zuo, Dewei Rao, Sainan Ma et al.

Valence engineering has been proved an effective approach to modify the electronic property of a catalyst and boost its oxygen evolution reaction (OER) activity, while the limited number of elements restricts the structural diversity and the active sites. Also, the catalyst performance and stability are greatly limited by cationic dissolution, ripening, or crystal migration in a catalytic system. Here we employed a widely used technique to fabricate heteroepitaxial pyrite selenide through dual-cation substitution and a boron dopant to achieve better activity and stability. The overpotential of Ni-pyrite selenide catalyst is decreased from 543 mV to 279.8 mV at 10 mA cm-2 with a Tafel slope from 161 to 59.5 mV dec-1. Our theoretical calculations suggest both cation and boron doping can effectively optimize adsorption energy of OER intermediates, promote the charge transfer among the heteroatoms, and improve their OER property. This work underscores the importance of modulating surface electronic structure with the use of multiple elements and provides a general guidance on the minimization of activity loss with valence engineering.