Chiral auxetic cellular structures were fabricated from Ti6Al4V alloy using the Selective Electron Beam Melting method, and tested experimentally under quasi-static and dynamic compression loading ...conditions. The experimental results were used to validate built computational models of auxetic cellular structure in LS-DYNA. The models were used to study the geometry effect on the Poisson’s ratio of the analysed chiral auxetic structure. The response of sandwich composite panels with auxetic core under blast loading was studied extensively computationally, where the maximum panel displacement and the Specific Energy Absorption (SEA) of the composite panel were evaluated. Three different methods for blast loading (ConWep, Smooth Particle Hydrodynamic, Multi-Material Arbitrary Lagrange-Eulerian) were compared and validated based on the experimental data. It was determined that larger thickness of the cover plate lowers the panel maximum displacement, while the SEA is larger when thinner cover plates are used. Also, it was shown that the chiral unit cell amplitude effect on the maximum displacement and SEA is, in most analysed cases, negligible in comparison to the cell length effect, which is more prominent. The presented study illustrates great potential of using sandwich structures with designed auxetic cellular cores to improve the response of modern composite structures to blast loading.
The development of natural inhibitors of polyphenol oxidase (PPO) is crucial in the prevention of enzymatic browning in fresh foods. However, few studies have focused on the effect of subsequent ...sterilization on their inhibition efficiency. This study investigated the influence and mechanism of high hydrostatic pressure (HHP) on the inhibition of PPO by epigallocatechin gallate (EGCG), cyanidin-3-O-glucoside (C3G), and ferulic acid. Results showed that under the conditions of 550 MPa/30 min, the activity of EGCG-PPO decreased to 55.92%, C3G-PPO decreased to 81.80%, whereas the activity of FA-PPO remained stable. Spectroscopic experiments displayed that HHP intensified the secondary structure transformation and fluorescence quenching of PPO. Molecular dynamics simulations revealed that at 550 MPa, the surface interaction between PPO with EGCG or C3G increased, potentially leading to a reduction in their activity. In contrast, FA-PPO demonstrated conformational stability. This study can provide a reference for the future industrial application of natural inhibitors.
•HHP treatment improved the inhibitory efficiency of PPO by EGCG or C3G•The activity of FA-PPO remained stable even at 550 MPa/30 min•TEM observed that HHP promoted the aggregation of PPO in the presence of EGCG•MD simulations showed an increase in interaction between PPO and inhibitors under HHP•FA was embedded inside the PPO to form a complex that exhibited pressure stability
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Three quinoxaline-based heterocycles namely, 6-methyl-2,3-diphenylquinoxaline (Q-CH3), 6-nitro-2,3-diphenylquinoxaline (Q-NO2) and 2,3-diphenylquinoxaline (Q-H) were evaluated as ...inhibitor for mild steel (MS) in 1 M HCl. Inhibition effectiveness of the Q-H, Q-CH3 and Q-NO2 tested using different computational simulations and experimental methods. Results showed that inhibition effectiveness of Q-H, Q-CH3 and Q-NO2increases with their concentration. Polarization results showed that Q-H, Q-CH3 and Q-NO2displayed anodic-type behaviour. Inhibition efficiencies of Q-H, Q-CH3 and Q-NO2 followed the order: 87.6% (Q-NO2) < 90.2% (Q-CH3)< 92.4%(Q-H) for Q-CH3. Presence of both electron withdrawing (-NO2) and donating (-CH3) substituents decrease the inhibition efficiency as compared to the parent compound however in decrease in protection power is more prominent in the presence of –NO2 substituent. Q-H, Q-CH3 and Q-NO2inhibit corrosion by adsorbing on MS surface and their adsorption mode followed Langmuir adsorption isotherm. Adsorption of Q-H, Q-CH3 and Q-NO2 on metallic surface reinforced with SEM-EDS and UV-visible studies of MS surfaces. Interaction mechanism of Q-H, Q-CH3 and Q-NO2with MS surface and their mode of adsorption was studies using DFT and MD (MD) simulations, respectively. Negative sign of adsorption energies (Eads) for Q-H, Q-CH3 and Q-NO2suggested that they adsorb spontaneously over MS surface.
Lipopolysaccharides (LPS) are major players in bacterial infection through the recognition by Toll-like receptor 4 (TLR4). The LPS chemical structure, including the oligosaccharide core and the lipid ...A moiety, can be strongly influenced by adaptation and modulated to assure bacteria protection, evade immune surveillance, or reduce host immune responses. Deep structural understanding of TLRs signaling is essential for the modulation of the innate immune system in sepsis control and inflammation, during bacterial infection. To advance this knowledge, we have employed computational techniques to characterize the TLR4 molecular recognition of atypical LPSs from different opportunistic members of α2-Proteobacteria, including Brucella melitensis, Ochrobactrum anthropi, and Ochrobactrum intermedium, with diverse immunostimulatory activities. We contribute to unraveling the role of uncommon lipid A chemical features such as bearing very long-chain fatty acid chains, whose presence has been rarely reported, on modulating the proper heterodimerization of the TLR4 receptor complex. Moreover, we further evaluated the influence of the different oligosaccharide cores, including sugar composition and net charge, on TLR4 activation. Our studies contribute to elucidating, from the molecular and biological perspectives, the impact of the α2-Proteobacteria LPS cores and the chemical structure of the atypical lipid A for immune system evasion in opportunistic bacteria.
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In this study, the influence of the integrability requirement on nonlinear Schrödinger equations with mixed derivatives is examined. The Rangwala–Rao (RR) equation is named after A. Rangwala, who in ...1990 was the first to quantify these effects in their entirety. The aim of our research is identifying how to generate individual waves and how they interact with one another. This is to get a better understanding of the dispersion effect and the progressive variation of the electric field envelope during pulse propagation in optical fibers. The direct algebraic method (DAM), the extended direct algebraic approach (exDAA), and the extended Riccati expansion technique (exREM) are used to develop unique solitary wave solutions for the model under consideration. These numerically calculated solutions illustrate the dynamic behavior of an optical pulse traveling through a cable. Comparing our results to those of other researchers demonstrates the originality of our work.
•Study of Nonlinear Dynamics of the Rangwala–Rao equation.•Analytical and numerical novel constructed results.•Investigating the obtained results’ accuracy.•Explaining the obtained solutions through some distinct types of sketches.
This study reports the evaluation of the anticorrosive performance of two macromolecular aromatic epoxy resins (ERs), namely, tetra glycidyl of ethylene dianiline (TGEDA) and hexaglycidyl Tris ...(p-ethylene dianiline) phosphoric triamide (HGEDPAT) and their polymer composite reinforced with Zinc for copper corrosion in 3% NaCl using the computational and experimental analyses. Electrochemical results showed that HGEDAPT cured with methylene dianiline (MDA) showed better protection efficiency with optimum corrosion current density (icorr) value of 2.0 μ cm−2 and the polarization resistance (Rp) value of 17.00 kΩ·cm2 than that of TGEDA-MDA having icorr value of 2.4 μ cm−2 and the Rp value of 15.24 kΩ·cm2. The anti-corrosive effect of TGEDA-MDA and HGEDAPT-MDA was evaluated in the presence of 5% zinc (Zn). Experimental results demonstrate that the presence of 5% of zinc in TGEDA-MDA and HGEDAPT-MDA formulations significantly enhanced their protection ability. The anticorrosive effect of the different formulations followed the order: ER1 (TGEDA-MDA) (potentiodynamic polarization (PDP); 90% and electrochemical impedance spectroscopy (EIS) 92%) < ER2 (HGEDAPT-MDA) (PDP; 92% and EIS 93%) < ER3 (TGEDA-MDA-5%Zn) (PDP; 96% and EIS 97%) < ER4 (HGEDAPT-MDA-5%Zn) (PDP; 97% and EIS 98.5%). Density functional theory (DFT) study revealed that ER1 and ER2 interact with the metallic surface using donor-acceptor interactions in which electron rich centers acted as most favorable sites for the interactions. Molecular dynamics (MD) simulations studies suggest that ER1 and ER2 acquire the flat or horizontal orientations and their orientations on metallic surface are largely influenced by the presence of zinc. Different experimental and computational studies are in good agreement.
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•Two epoxy resins (ER1 and ER2) and their Zn (ER3 and ER4) composites tested as coatings for copper in 3% NaCl medium•ERs-Zn composites showed better corrosion protection than that of pure ERs.•Protection efficiencies followed the order: ER1 < ER2 < ER3 < ER4.•Epoxy resins ER1 and ER2 interact with copper surface using donor-acceptor.•Epoxy resins ER1 and ER2 strongly and chemically adsorbed on metallic surface
In this study we used simulation of genetic parameters based on microsatellite data to investigate the reproductive system of three Hymenaea courbaril L. species populations. Different selfing, ...migration and clonal reproduction rates were tested using the Easypop software. The results suggest the presence of both sexual and clonal reproduction in these populations. The simulated populations showed gradual decrease of the genetic diversity due the low gene flow caused by fragmentation. Due to connectivity importance, it is suggested expanding the area and replacing the explored trees using high genetic diversity germplasm in order to minimize the negative effects of fragmentation.
Neste estudo foram usadas simulações de parâmetros genéticos com base em dados de microssatélites para investigar o sistema reprodutivo de três populações de Hymenaea courbaril L. Foram testadas diferentes taxas de autofecundação, migração e reprodução clonal usando o software Easypop. Os resultados sugerem a presença de reprodução sexual e clonal nessas populações. Houve diminuição gradual da diversidade genética devido ao baixo fluxo gênico ocasionado pela fragmentação. Devido à importância da conectividade, sugere-se a expansão da área e substituição das árvores exploradas por germoplasma de elevada diversidade genética, visando a minimizar os efeitos negativos da fragmentação.
This study investigates novel solutions to the fractional Caudrey–Dodd–Gibbon (FCDG) equation, which is a nonlinear partial differential equation that models shallow water waves in channels with ...varying width and depth. The research employs two computational simulations, namely the Bernoulli sub-equation (BSE) function and extended Khater (EKHA) methods, to analyze the FCDG equation and obtain analytical solutions. The obtained solutions are presented graphically and discussed in various styles, including hyperbolic, rational, and trigonometric formats. The study also examines the strengths and limitations of each method and presents case studies simulating different scenarios, such as wave breaking, run-up, and tsunami propagation. The importance of validation and verification using experimental data or analytical solutions is emphasized to ensure the reliability of numerical solutions. Moreover, the potential impact of computational simulations in predicting real-world shallow water wave behavior, particularly in coastal hazards and ocean engineering, is discussed. This study highlights the usefulness of analytical and numerical techniques in accurately predicting complex phenomena.
•Nonlinear dynamics’ investigation of nonlinear local fractional Caudrey–Dodd–Gibbon equation.•Analytical and numerical novel constructed results.•Investigating the obtained results’ accuracy.•Explaining the obtained solutions through some distinct types of sketches.
The organic compounds containing –CN and –NO2 substituents are extensively used as metal corrosion inhibitors. The –CN and –NO2 substituents are electron withdrawing in nature and they expected to ...decrease the inhibition efficiency of organic inhibitors because of their –R-effect and/or –I-effect. However, either in too big or too small organic inhibitors, –CN and –NO2 substituents increase the inhibition effectiveness of the inhibitors. These substituents also affect the solubility of their base compounds in polar electrolytes. Inhibition effectiveness of macromolecules, oligomers and polymers expected to increase in the presence –CN and –NO2 substituents. Computational based analyses using Density functional theory (DFT, molecular dynamics' (MD) and Monte Carlo (MC) simulations showed that –CN and –NO2 substituents greatly affect the charge sharing reactions taking place between metal and organic inhibitors. Orientation of the organic inhibitors over the metallic surface is also greatly depends upon the presence of –CN and –NO2 substituents. In general, the –CN and –NO2 containing moieties acquire vertical orientation and cover fewer metallic surface area. Present review article features the collection of some major publications that are published on recent advancements in the field of corrosion inhibition using –NO2 and –CN substituents containing compounds. The description of present article will leads to the designing and synthesis of effective corrosion inhibitors.
•Present review article describes the collection of compounds containing –CN and –NO2 as corrosion inhibitors.•The –CN and –NO2 expected to decrease the inhibition efficiency because of their –R-effect and/or –I-effect.•The –CN and –NO2 substituents greatly affect the charge sharing reactions.•–CN and –NO2 substituents play crucial role in determining the orientation of corrosion inhibitors.•In general, the –CN and –NO2 containing moieties acquire vertical orientation.
•experimental testing of graded chiral auxetic structures under compression and shear loading.•development and validation of the computational models•calculation of shear and Young’s modulus of ...analysed auxetic structures.•evaluation of influence of graded porosity on the mechanical response of auxetic chiral structure.
Graded chiral auxetic cellular metal structures were produced from copper alloy powder using Selective Electron Beam Melting (SEBM) technique and tested under compressive and shear loading conditions. The predesigned geometry of chiral structures has a variable chiral amplitude through the length of the specimens, which results in graded porosity of the analyzed auxetic structures. The deformation mechanisms and mechanical response were evaluated with compression and shear testing at two loading velocities. The infrared thermography has been used to track the evolution of plastic deformation in the specimens. The deformation process under compression loading starts in the area with the largest chiral amplitude and then continues through the whole height of the specimen. The shear loading shows two significantly different groups of responses, which are affected by local defects causing the start of failure in different parts of structure. The results of experimental testing were further used for validation of developed finite element models of chiral structures. The influence of graded porosity on the mechanical response of chiral structures was evaluated with parametric computational simulations and compared to the non-graded structure with constant chiral amplitude and same weight. The non-graded auxetic structure offers a stiffer response due to deformation uniformly distributed through the height of the specimens but fails abruptly at lower strains.
