Functionally graded conformal lattice structures (FGCLSs) are a particular type of lattice structure in which lattice unit cells are populated following structural boundaries and the density of the ...lattice unit cells is optimally distributed. Additionally, additively manufactured parts are reported to have anisotropic mechanical properties that highly depend on the part build orientations. This is extremely important in designing FGCLS parts where orientations of lattice unit cells are not uniform, making the build orientation selection more challenging. In this study, a concurrent density distribution and build orientation optimization framework of additively manufactured FGCLSs for structure-performance maximization was developed. The proposed approach was validated via case studies on lightweight part design for compliance minimization, with three design examples having geometric complexity levels varying from low to high. The results showed that the proposed concurrent optimization method was more effective at enhancing structural performance than optimizing only the density distribution of the structure. In addition, the build orientation configurations determined by the proposed method provided better structural performance compared to those determined using other slicing software. Moreover, compared to the pseudo-worst build orientation configuration, the configuration obtained from the proposed approach could enhance structural performance by up to 47.56%.
•A concurrent structure–process optimum part design with conformal lattice structure.•Euler’s angle was applied for build orientation modeling.•Build orientation dependent anisotropic lattice scaling law was developed.•Density distribution (structure) and build orientation (process) are concurrently optimized.
The nanopattern on the surface of Clanger cicada (Psaltoda claripennis) wings represents the first example of a new class of biomaterials that can kill bacteria on contact based solely on their ...physical surface structure. The wings provide a model for the development of novel functional surfaces that possess an increased resistance to bacterial contamination and infection. We propose a biophysical model of the interactions between bacterial cells and cicada wing surface structures, and show that mechanical properties, in particular cell rigidity, are key factors in determining bacterial resistance/sensitivity to the bactericidal nature of the wing surface. We confirmed this experimentally by decreasing the rigidity of surface-resistant strains through microwave irradiation of the cells, which renders them susceptible to the wing effects. Our findings demonstrate the potential benefits of incorporating cicada wing nanopatterns into the design of antibacterial nanomaterials.
The emergence of additive manufacturing (AM) has enabled the design of complex structures with high performance, such as functionally graded cellular structures (FGCSs). Concurrent topology ...optimization is commonly utilized for designing FGCSs; however, this approach suffers from an extremely high computational cost due to the complexity of the design problem. Recently, level-set-based methods, which rely on the implicit-based modeling technique, have gained increased attention and been considered as an efficient design tool for structures fabricated with AM. In this work, a multiscale structural optimization method for FGCS design utilizing level-set descriptions is proposed. Contrary to the well-known level-set topology optimization, in this approach, the shape is represented and parameterized with implicit functions, and the optimization process is performed to find the optimal parameters. The proposed method can replace topology optimization for microscale structural optimization within the multiscale structural design with reduced computation cost and comparable optimally designed results. Moreover, the unique behaviors of pre-selected cellular structures could be maintained during the optimization process by proper parametric constraints. The proposed design approach was validated through two design examples, both of which demonstrate remarkable structural performance enhancements in comparison with the single-scale design approach. Furthermore, two three-dimensional design examples, commonly found in automotive and aerospace industries, further prove the applicability of the proposed method in practice.
With the recent development of laser scanning technology, the variety of applications of laser scanners has increased. One typical application is object recognition from laser-scanned point cloud ...models. On large-scale construction sites such as refineries and industrial plants, object recognition from point cloud models has been widely employed for construction progress monitoring, assembly inspections, and maintenance purposes. Pipelines are among the main objects of interest with regard to object recognition on such sites. There has been extensive research on recognizing pipes in pipelines; however, research on recognizing pipe-connecting elbows is still lacking. Most representative elbow recognition methods are centerline-based and connectivity-based methods. These methods do not use laser-scanned points directly; instead, they employ feature values that are calculated from laser-scanned points. However, these feature values are easily affected by noise and occlusion; therefore, the elbow recognition results could be inaccurate owing to noisy and occluded point cloud models. In this paper, we propose an automatic pipe and elbow recognition method robust against noise and occlusion in which pipes and elbows are recognized directly from laser-scanned points. This method starts with pipeline extraction, followed by elbow classification based on curvature information. Falsely classified points are filtered using convolutional neural network-based primitive classification. After elbow recognition is completed, pipe classification and recognition are performed. Experimental results obtained from three different point cloud models demonstrated that the proposed method recognizes pipes and elbows with high accuracy from noisy and occluded point cloud models.
•An automatic pipe and elbow recognition method from 3D point cloud is proposed.•Curvature information was used to classify points on elbows from the pipelines.•2D CNN-based primitive classifier was used to filter out falsely classified points.•The proposed method was validated with three different point cloud models.
Summary
Biofuel has emerged as an alternative source of energy to reduce the emissions of greenhouse gases in the atmosphere and combat global warming. Biofuels are classified into first, second, ...third and fourth generations. Each of the biofuel generations aims to meet the global energy demand while minimizing environmental impacts. Sustainability is defined as meeting the needs of the current generations without jeopardizing the needs of future generations. The aim of sustainability is to ensure continuous growth of the economy while protecting the environment and societal needs. Thus, this paper aims to evaluate the sustainability of these four generations of biofuels. The objectives are to compare the production of biofuel, the net greenhouse gases emissions, and energy efficiency. This study is important in providing information for the policymakers and researchers in the decision‐making for the future development of green energy. Each of the biofuel generations shows different benefits and drawbacks. From this study, we conclude that the first generation biofuel has the highest biofuel production and energy efficiency, but is less effective in meeting the goal of reducing the greenhouse gases emission. The third generation biofuel shows the lowest net greenhouse gases emissions, allowing the reduction of greenhouse gases in the atmosphere. However, the energy required for the processing of the third generation biofuel is higher and, this makes it less environmentally friendly as fossil fuels are used to generate electricity. The third and fourth generation feedstocks are the potential sustainable source for the future production of biofuel. However, more studies need to be done to find an alternative low cost for biofuel production while increasing energy efficiency.
• First generation biofuel has the highest biofuel yield and energy efficiency. However, the production of the biofuel opposed many sustainable development goals.
• Third and fourth generation biofuels show potential as a sustainable future green energy.
• Methods of lipid extraction of microalgae biofuel and environmental consequences of the fourth generation biofuel should be further explored.
It is commonly accepted that nanoparticles (NPs) can kill bacteria; however, the mechanism of antimicrobial action remains obscure for large NPs that cannot translocate the bacterial cell wall. It is ...demonstrated that the increase in membrane tension caused by the adsorption of NPs is responsible for mechanical deformation, leading to cell rupture and death. A biophysical model of the NP–membrane interactions is presented which suggests that adsorbed NPs cause membrane stretching and squeezing. This general phenomenon is demonstrated experimentally using both model membranes and Pseudomonas aeruginosa and Staphylococcus aureus, representing Gram‐positive and Gram‐negative bacteria. Hydrophilic and hydrophobic quasi‐spherical and star‐shaped gold (Au)NPs are synthesized to explore the antibacterial mechanism of non‐translocating AuNPs. Direct observation of nanoparticle‐induced membrane tension and squeezing is demonstrated using a custom‐designed microfluidic device, which relieves contraction of the model membrane surface area and eventual lipid bilayer collapse. Quasi‐spherical nanoparticles exhibit a greater bactericidal action due to a higher interactive affinity, resulting in greater membrane stretching and rupturing, corroborating the theoretical model. Electron microscopy techniques are used to characterize the NP–bacterial‐membrane interactions. This combination of experimental and theoretical results confirm the proposed mechanism of membrane‐tension‐induced (mechanical) killing of bacterial cells by non‐translocating NPs.
The mechanism of antimicrobial action for nanoparticles that are unable to translocate across the bacterial cell wall remains obscure. In this work, it is demonstrated that the increase of membrane tension provoked by the adsorption of nanoparticles is responsible for mechanical deformation of the membrane, which leads to bacterial cell rupture and death.
Lattice structures are well-known as a solution for designing parts with lightweight and multifunctional characteristics. Owing to the advancement of additive manufacturing (AM), the development of ...design methods for additively manufactured lattice structures has extensively progressed, especially for functionally graded lattice structures (FGLS). Despite plenty of available design frameworks, the application of AM constraints in the design of FGLS is limited to geometric issues. Further, there is a lack of design methods that consider the unique physical properties of additively manufactured parts, especially the anisotropic characteristics induced by AM processes. This paper proposes a novel method for the design of additively manufactured functionally graded lattice structures with the consideration of AM anisotropic properties. In addition, a customized anisotropic AM-Lattice material model that supports the design of FGLS through the density-variable topology optimization is proposed. Moreover, Fused Deposition Modeling (FDM) process in which the process-induced anisotropy of AM is clearly demonstrated is focused. The design method was validated by the three-point bending-beam design problem, a classical design problem for validating topology optimization. The results, showing agreements between simulations and experiments, prove the validity and practicality of the proposed method.
Ferroptosis is recently identified form of regulated cell death which differs from previously identified cell death in a way that it is driven by iron-dependent lipid peroxide accumulation. ...Morphologically, cell volume shrinkage and increased mitochondrial membrane density are main features which characterize this form of cell death. Molecular mechanism of ferroptosis induction involved suppression of the phospholipid glutathione peroxidase 4 (GPX4) and further intracellular accumulation of lipid reactive oxygen species (ROS), a process in which iron is involved; either via inhibition of system Xc- (cystine/glutamate antiporter) or direct inhibition of GPX4. Several other pathways like RAS/MAPK and NRF2 are found to be involved in ferroptosis regulation. However, the precise mechanism of ferroptosis induction is not revealed till date. Like other regulated cell deaths, ferroptosis plays important role in tumor suppression and progression as revealed by several scientific reports. This review summarizes basic information about discovery of this novel cell death mechanism including molecular mechanism of its induction and further explains the roles of ferroptosis in human cancers.
Display omitted
•Ferroptosis a newly discovered iron dependent programmed cell death.•Ferroptosis activation a promising strategy for diagnosis and therapeutic intervention in cancer.•Ferroptosis inducing agents as an attractive therapeutic strategy.•Ferroptosis induction involved suppression of the phospholipid GPX4.
A widely used herbicide for controlling weeds, glyphosate, is causing environmental pollution. It is necessary to remove it from environment using a cost-effective and eco-friendly method. The aims ...of this study were to isolate glyphosate-degrading bacteria and to optimize their degradative conditions required for bioremediation. Sixteen bacterial strains were isolated through enrichment and one strain,
Rhodococcus soli
G41, demonstrated a high removal rate of glyphosate than other strains. Response surface methodology was employed to optimize distinct environmental factors on glyphosate degradation of G41 strain. The optimal conditions for the maximum glyphosate degradation were found to have the NH
4
Cl concentration of 0.663% and glyphosate concentration of 0.115%, resulting in a maximum degradation of 42.7% after 7 days. Bioremediation analysis showed 47.1% and 40% of glyphosate in unsterile soil and sterile soil was removed by G41 strain after 14 days, respectively. The presence of
soxB
gene in G41 strain indicates that the glyphosate is degraded via the eco-friendly sarcosine pathway. The results indicated that G41 strain has the potential to serve as an in-situ candidate for bioremediation of glyphosate polluted environments.
Display omitted
•Pigment-protein complex was recovered from Spirulina platensis.•C-phycocyanin and allophycocyanin were successfully extracted using sonoprocessing.•Optimization of ultrasound ...enhanced the purity and yield of the targeted compound.•A purification factor of 5.23 and recovery of 95.1% of c-phycocyanin was obtained.•C-phycocyanin was characterized using SDS-PAGE analysis.
Current practice for C-phycocyanin (CPC) extraction from fresh biomass is greatly perishable, so dried biomass is preferable for longer storage life and saving spaces for small scale industries. However, the resistance of dried biomass towards cell disruption is higher compared to fresh biomass. Therefore, this work aims to develop an effective technique for the extraction of CPC from dried Spirulina sp. This study addresses the effect of sonoprocessing-assisted with liquid biphasic flotation (LBF) for the extraction and purification of CPC and allophycocyanin (APC). The application of ultrasound was optimized by various parameters such as amplitude (20 to 30%), sonication time in pulse mode (5 to 25 s), resting time in pulse mode (5 to 25 s) and the total time of sonication (3 to 12 min). While for the liquid biphasic flotation, the studied parameters were air flowrate (75 to 175 cc/min), a volume ratio of both phases (1:0.5 to 1:1.5), flotation time (3 to 12 min), and weight of biomass (0.1 to 0.6 g). Results of both CPC and APC were determined using the optimized conditions and subjected to SDS-PAGE analysis. Total purification factor of 5.23 and recovery of 95.10% were obtained using 30% amplitude, 5 s ON/5s OFF (pulse mode), 10 min sonication, volume ratio 1:1, 100 cc/min air flowrate, 7 min flotation time, and 0.45 g biomass. This study proves that the suggested method enhances efficiency in the recovery of CPC and demonstrates the synergistic effect of sonoprocessing with LBF in extracting CPC and other biomolecules from microalgae.
PDF
