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In the present work, the effect of impactor nose shape and fiber stacking sequences on the low‐velocity impact properties of hybrid Kevlar/basalt fiber reinforced epoxy composites was investigated. The composite specimens were prepared using hand lay‐up method with six types of fiber stacking sequences including sandwich hybrid, intercalated hybrid and not‐hybrid. The impact tests were conducted using three types of impactor nose shapes (hemispherical, conical, and flat) at two impact energies of 40 and 60 J. Some characteristics of the composites like maximum force, absorbed energy, and damage area were evaluated. Also, the impact behavior of the composites was simulated in Abacus finite element software and the obtained results were compared with the experimental values. The results indicated the hybridization of Kevlar by basalt fibers (intercalated hybrid) considerably improved the impact properties of the specimen. Besides, when the conical impactor was employed, the highest absorbed energy and damaged area were obtained. [ABSTRACT FROM AUTHOR]

Composite laminates have found extensive application in various industries, and numerous studies have been conducted to investigate their behavior in flat sheet configurations. The present study aims to extend this research by examining the behavior of convex composite specimens subjected to high velocity impact (HVI), and comparing their energy absorption and failure area to that of flat sheets made of glass fibers. Additionally, we seek to investigate the influence of curvature diameter on the energy absorption and fiber failure percentage of the composite specimens. Four series of composite laminates with distinct geometries, comprising a flat specimen and three convex composite specimens, were fabricated with nine layers each and diameters of 10, 15, and 20 cm. All specimens were fully clamped and subjected to empirical gas gun impact tests at three different velocities of 200, 250, and 300 m/s. The velocity values before and after the impact were measured using velocity sensors, and the energy absorption of the laminates was computed. Of the tested composite specimens, those with smaller diameters and greater curvature exhibited reduced fiber damage percentage and increased energy absorption. Compared to the flat specimens made of glass fibers, the convex specimens with a diameter of 10 cm exhibited an energy absorption increase of approximately 47%, while the specimens with diameters of 15 and 20 cm showed approximately energy absorption increases of 42% and 7%, respectively. The results were confirmed through simulation using finite element software ABAQUS/Explicit. Highlights: Curved E‐glass laminates studied under high velocity impact which is done experimentally and numerically.Convexity increases energy absorption capacity of E‐glass reinforced epoxy composites.The results show that convexity can absorb more energy compared to flat panels.The damaged area of curved laminates are smaller than the flat one.The findings suggest that convexity can be a useful design feature for improving impact resistance in various applications. [ABSTRACT FROM AUTHOR]

Risk screening tools play a crucial role in identifying potential high‐risk non‐native (NN) fish species. In this study, potentially invasive NN fish species in the Anzali Wetland Complex (AWC), which is located on the south coast of the Caspian Sea (Iran), were identified using the Aquatic Species Invasiveness Screening Kit (AS‐ISK). Twenty‐nine freshwater fish species were screened of which 13 exist in the AWC and 16 in close proximity to it ("horizon" species). Receiver operating characteristic curve analysis showed that AS‐ISK could discriminate reliably between non‐invasive and invasive fish species for the AWC. Mean threshold scores were 3.25 for the Basic Risk Assessment (BRA) and 11.75 for the BRA + CCA (BRA + Climate Change Assessment), and these, respectively, classified 89.7% and 86.2% of the species as high risk. The CCA resulted in an increase in the BRA scores for 86.2% of the species, suggesting the need to account in future NN species management for a likely increased invasiveness of those species under future climate conditions. These results suggest that AS‐ISK could prove an effective tool for identifying potentially invasive NN freshwater fishes in other wetlands of the Caspian Sea basin. [ABSTRACT FROM AUTHOR]

In the present study, trypsin from Plodia interpunctella ( Hübner) is characterized to discover sequence, biochemical and structural features. This enzyme is purified by ion exchange chromatography using fast protein liquid chromatography on proteins from fifth-instar larvae. The enzyme is optimally active at 50 °C and pH 11.0. The kinetic parameters ( Km and Vmax) of the enzyme are 5.3 ± 0.6 µ m and 31 ± 1.3 nmol min−1 mg−1, respectively (using Nα-benzoyl- l-arginine ρ-nitroanilide hydrochloride as substrate). The enzyme is inhibited by the addition of Cu2+ and Mn2+, whereas it is activated by Li+ at high concentrations. Moreover, the enzyme is almost completely inhibited in the presence of Nα-tosyl- l-lysine chloromethyl ketone hydrochloride and phenylmethanesulphonyl fluoride. To understand some characteristics of P. interpunctella trypsin, including active site structure and alkaline pH profile, a reliable structural model of P. interpunctella trypsin is built based on the Fusarium oxisporum ( Schlecht) trypsin cystal structure ( Protein Data Bank code: 1GDU). The secondary structure content of the purified trypsin from near-ultraviolet circular dichroism data shows considerable similarities with that of P. interpunctella trypsin predicted structure. Analysis of p Ka values of active site residues, a type of amino acid residue in the active site cleft and the surface charges of the model and Tribolium castaneum ( Herbst) trypsin structure as an insect species from different orders reveals some differences between them. These differences might effect on the microenvironment of the active site cleft and consequently shift its pH profile. The application of multiple theoretical and experimental techniques is well adapted to predict the enzyme structure with high accuracy and this could help in the design of a powerful inhibitor for trypsin with ideal properties. [ABSTRACT FROM AUTHOR]