Search

Insect legs play a crucial role in various modes of locomotion, including walking, jumping, swimming, and other forms of movement. The flexibility of their leg joints is critical in enabling various modes of locomotion. The frog‐legged leaf beetle Sagra femorata possesses remarkably enlarged hind legs, which are considered to be a critical adaptation that enables the species to withstand external pressures. When confronted with external threats, S. femorata initiates a stress response by rapidly rotating its hind legs backward and upward to a specific angle, thereby potentially intimidating potential assailants. Based on video analysis, we identified 4 distinct phases of the hind leg rotation process in S. femorata, which were determined by the range of rotation angles (0°−168.77°). Utilizing micro‐computed tomography (micro‐CT) technology, we performed a 3‐dimensional (3D) reconstruction and conducted relative positioning and volumetric analysis of the metacoxa and metatrochanter of S. femorata. Our analysis revealed that the metacoxa–trochanter joint is a “screw‐nut” structure connected by 4 muscles, which regulate the rotation of the legs. Further testing using a 3D‐printed model of the metacoxa–trochanter joint demonstrated its possession of a self‐locking mechanism capable of securing the legs in specific positions to prevent excessive rotation and dislocation. It can be envisioned that this self‐locking mechanism holds potential for application in bio‐inspired robotics. [ABSTRACT FROM AUTHOR]

Simple Summary: The developmental process, divided into four different stages (egg, larva, pupa and adult), is the main reason for their remarkable diversification and expansion of the insect group Holometabola. Advanced morphological techniques have been used to demonstrate the 3D thoracic anatomical structures of the holometalous model organism fruit fly, Drosophila melanogaster, before and after emergence, in order to uncover the transformation process of the muscles, nerves, and gut during development. Skeletal changes affect the original positions of the muscles. The muscles vary in size, not only becoming longer and broader, but also shorter and narrower. Different muscle shapes may appear during development. The number of bundles may also vary. The soft tissues in the body may fix the free ends of the growing muscles, and a strong adult skeleton likely causes the absence of some muscles and tendons. The flight muscles appear very early, probably to achieve full functionality of these very large adult-specific muscles in time. There are some differences during the same developmental period between the two sexes. Most muscles of the larvae and adults with similar attachment positions change their functions from supporting crawling to supporting flying and walking under the control of a more complex ventral nerve cord. The midguts of the larva and the adult are nearly the same. The model organism Drosophila melanogaster, as a species of Holometabola, undergoes a series of transformations during metamorphosis. To deeply understand its development, it is crucial to study its anatomy during the key developmental stages. We describe the anatomical systems of the thorax, including the endoskeleton, musculature, nervous ganglion, and digestive system, from the late pupal stage to the adult stage, based on micro-CT and 3D visualizations. The development of the endoskeleton causes original and insertional changes in muscles. Several muscles change their shape during development in a non-uniform manner with respect to both absolute and relative size; some become longer and broader, while others shorten and become narrower. Muscular shape may vary during development. The number of muscular bundles also increases or decreases. Growing muscles are probably anchored by the tissues in the stroma. Some muscles and tendons are absent in the adult stage, possibly due to the hardened sclerites. Nearly all flight muscles are present by the third day of the pupal stage, which may be due to the presence of more myofibers with enough mitochondria to support flight power. There are sexual differences in the same developmental period. In contrast to the endodermal digestive system, the functions of most thoracic muscles change in the development from the larva to the adult in order to support more complex locomotion under the control of a more structured ventral nerve cord based on the serial homology proposed herein. [ABSTRACT FROM AUTHOR]

The safety diagnostic inspection of large plate structures, such as nuclear power plant containment liner plates and aircraft wings, is an important issue directly related to the safety of life. This research intends to present a more quantitative defect imaging in the structural health monitoring (SHM) technique by using a wide range of diagnostic techniques using guided ultrasound. A noncontact detection system was applied to compensate for such difficulties because direct access inspection is not possible for high-temperature and massive areas such as nuclear power plants and aircraft. Noncontact systems use unstable pulse laser and air-coupled transducers. Automatic detection systems were built to increase inspection speed and precision and the signal was measured. In addition, a new Difference Hilbert Back Projection (DHB) algorithm that can replace the reconstruction algorithm for the probabilistic inspection of damage (RAPID) algorithm used for imaging defects has been successfully applied to quantitative imaging of plate structure defects. Using an automatic detection system, the precision and detection efficiency of data collection has been greatly improved, and the same results can be obtained by reducing errors in experimental conditions that can occur in repeated experiments. Defects were made in two specimens, and comparative analysis was performed to see if each algorithm can quantitatively represent defects in multiple defects. The new DHB algorithm presented the possibility of observing and predicting the growth direction of defects through the continuous monitoring system.

Microstructure evolution and hardening effect of pure tungsten and Wâ€"1.5%ZrO2 alloy under carbon ion irradiation are investigated by using transmission electron microscopy and nano-indentation. Carbon ion irradiation is performed at 700 °C with irradiation damages ranging from 0.25 dpa to 2.0 dpa. The results show that the irradiation defect clusters are mainly in the form of dislocation loop. The size and density of dislocation loops increase with irradiation damages intensifying. The Wâ€"1.5%ZrO2 alloy has a smaller dislocation loop size than that of pure tungsten. It is proposed that the phase boundaries have the ability to absorb and annihilate defects and the addition of ZrO2 phase improves the sink strength for irradiation defects. It is confirmed that the Wâ€"1.5%ZrO2 alloy shows a smaller change in hardness than the pure tungsten after being irradiated. From the above results, we conclude that the addition of ZrO2 into tungsten can significantly reduce the accumulation of irradiated defects and improve the irradiation resistance behaviors of the tungsten materials. [ABSTRACT FROM AUTHOR]

Nitrogen‐fixing root nodules are formed by symbiotic association of legume hosts with rhizobia in nitrogen‐deprived soils. Successful symbiosis is regulated by signals from both legume hosts and their rhizobial partners. HmuS is a heme degrading factor widely distributed in bacteria, but little is known about the role of rhizobial hmuS in symbiosis with legumes. Here, we found that inactivation of hmuSpSym in the symbiotic plasmid of Mesorhizobium amorphae CCNWGS0123 disrupted rhizobial infection, primordium formation, and nitrogen fixation in symbiosis with Robinia pseudoacacia. Although there was no difference in bacteroids differentiation, infected plant cells were shrunken and bacteroids were disintegrated in nodules of plants infected by the ΔhmuSpSym mutant strain. The balance of defence reaction was also impaired in ΔhmuSpSym strain‐infected root nodules. hmuSpSym was strongly expressed in the nitrogen‐fixation zone of mature nodules. Furthermore, the HmuSpSym protein could bind to heme but not degrade it. Inactivation of hmuSpSym led to significantly decreased expression levels of oxygen‐sensing related genes in nodules. In summary, hmuSpSym of M. amorphae CCNWGS0123 plays an essential role in nodule development and maintenance of bacteroid survival within R. pseudoacacia cells, possibly through heme‐binding in symbiosis. Summary Statement: We characterize the hmuSpSym gene located in the symbiotic plasmid of Mesorhizobium amorphae CCNWGS0123 that participates in symbiosis with Robinia pseudoacacia. Inactivation of hmuSpSym underpins damaged symbiotic phenotypes and necrotic bacteroids, which potentially affects symbiosis via HmuSpSym as a heme‐binding factor. [ABSTRACT FROM AUTHOR]