Anisotropic nanomechanical properties of bovine horn using modulus mapping

Bovine horns are durable that they can withstand an extreme loading force which with special structures and mechanical properties. In this paper, we apply quasi-static nanoindentation and modulus mapping techniques to research the nanomechanical properties of bovine horn in the transverse direction (TD) and longitudinal direction (LD). In quasi-static nanoindentation, the horn’s modulus and hardness in the inner layer and the outer layer demonstrated a gradual increase in both TD and LD. Laser scanning confocal microscopy (LSCM) revealed microstructure in the horn with wavy morphology in the TD cross-section and laminate in the LD cross-section. When using tensile tests or quasi-static nanoindentation tests alone, the anisotropy of the mechanical properties of bovine horn were not obvious. However, when using modulus mapping, storage modulus (E′), loss modulus (E″) and loss ratio (tan δ) are clearly different depending on the position in the TD and LD. Modulus mapping is proposed as accurately describing the internal structures of bovine horn and helpful in understanding the horn’s energy-absorption, stiffness and strength that resists forces during fighting

Bio-inspirations for the Development of Light Materials based on the Nanomechanical Properties and Microstructures of Beetle Dynastes tityus

Dynastes tityus (D. tityus) is a typical beetle whose elytra are light and strong. The primary function of elytra is to protect beetle’s hindwings. In this paper, D. tityus elytra were selected as the biological prototype for the investigation to obtain bio-inspirations for the design and development of light materials with high ratio of strength to mass. Firstly, the microstructure investigation and quasi-static nanoindentation tests have been carried out on the ten samples of the selected elytra of D. tityus to reveal their mechanical properties and microstructures. Secondly, based on the findings from the microstructure investigation and nanoindentation tests, three models of bio-inspired materials have been proposed for further study to gain the deep understanding of the relationships between the special mechanical characteristics and microstructures. Then Finite Element Analysis (FEA) simulations have been performed on the three models for harvesting the bio-inspirations for the initial design of light materials. Finally, through comparative analysis of the findings from the microstructure investigation, the nanoindentation tests and the simulations, some meaningful bio-inspirations have been reaped for the future optimization of the design and development of light materials with high ratio of strength to mass

Research on Biomimetic Models and Nanomechanical Behaviour of Membranous Wings of Chinese Bee Apis cerana cerana

The structures combining the veins and membranes of membranous wings of the Chinese bee Apis cerana cerana Fabricius into a whole have excellent load-resisting capacity. The membranous wings of Chinese bees were taken as research objects and the mechanical properties of a biomimetic model of membranous wings as targets. In order to understand and learn from the biosystem and then make technical innovation, the membranous wings of Chinese bees were simulated and analysed with reverse engineering and finite element method. The deformations and stress states of the finite element model of membranous wings were researched under the concentrated force, uniform load, and torque. It was found that the whole model deforms evenly and there are no unusual deformations arising. The displacements and deformations are small and transform uniformly. It was indicated that the veins and membranes combine well into a whole to transmit loads effectively, which illustrates the membranous wings of Chinese bees having excellent integral mechanical behaviour and structure stiffness. The realization of structure models of the membranous wings of Chinese bees and analysis of the relativity of structures and performances or functions will provide an inspiration for designing biomimetic thin-film materials with superior load-bearing capacity

The mechanism of resistance-reducing/anti-adhesion and its application on biomimetic disc furrow opener

The black soil of Northeast China is sticky and agglomerates easily, which often adheres to the surface of a traditional furrow opener during the furrowing process. In this paper, biomimetic design principles in resistance-reducing, anti-adhesion and resistance-reducing mechanism of biomimetic disc furrow opener were studied. Nine kinds of singular convex hull, nine kinds of singular wedge and nine kinds of mixed convex hull and wedge structural biomimetic disc furrow opener were designed, and the furrowing process with the soil simulated by finite element method (FEM). Three types of biomimetic disc furrow opener with less resistance were manufactured by laser processing for comparative test in soil bin based on the simulation results. The test results showed that the resistance of the biomimetic disc furrow opener was less than that of the ordinary disc. The soil-disc stress, influence of biomimetic structures, moisture content and furrow speeds on resistance were discussed. The resistance-reducing rate of D-BC-3 reached the maximum value 15.36% at the furrow speed of 0.6 m/s and the soil moisture content of 20%. It is believed that the biomimetic design principles can provide the significant inspirations for the future design of disc furrow opener with drag reduction

A Simulation of the Flight Characteristics of the Deployable Hindwings of Beetle

An insect is an excellent biological object for the bio-inspirations to design and develop a MAV. This paper presents the simulation study of the flight characteristics of the deployable hindwings of beetle, Dorcustitanus platymelus. A 3D geometric model of the beetle was obtained using a 3D laser scanning technique. By studying its hindwings and flight mechanism, the mathematical model of the flapping motion of its hindwings was analyzed. Then a simulation analysis was carried out to analyze and evaluate the flapping flying aerodynamic characteristics. After that, the flow of blood in the hindwing veins was studied through simulation to determine the maximum pressure on a vein surface and the minimum blood flow in flight. A number of interesting bio-inspirations were obtained. It is believed that these findings can be used for the design and development of a MAV with similar flying capabilities to a natural beetle

Prevailing I292V PB2 mutation in avian influenza H9N2 virus increases viral polymerase function and attenuates IFN-β induction in human cells

Adaptation of PB2 protein is important for the establishment of avian influenza viruses in mammalian hosts. Here, we identify I292V as the prevalent mutation in PB2 of circulating avian H9N2 and pandemic H1N1 viruses. The same dominant PB2 mutation is also found in most human isolates of emergent avian H7N9 and H10N8 viruses. In human cells, PB2-292V in H9N2 virus has the combined ability of conferring higher viral polymerase activity and stronger attenuation of IFN-β induction than that of its predecessor PB2-292I. IFN-β attenuation is accompanied by higher binding affinity of PB2-292V for host mitochondrial antiviral signalling protein, an important intermediary protein in the induction of IFN-β. In the mouse in vivo model, PB2-292V mutation increases H9N2 virus replication with ensuing increase in disease severity. Collectively, PB2-292V is a new mammalian adaptive marker that promotes H9N2 virus replication in mammalian hosts with the potential to improve transmission from birds to humans

The DNA-sensing AIM2 inflammasome controls radiation-induced cell death and tissue injury

Acute exposure to ionizing radiation induces massive cell death and severe damage to tissues containing actively proliferating cells, including bone marrow and the gastrointestinal tract. However, the cellular and molecular mechanisms underlying this pathology remain controversial. Here, we show that mice deficient in the double-stranded DNA sensor AIM2 are protected from both subtotal body irradiation-induced gastrointestinal syndrome and total body irradiation-induced hematopoietic failure. AIM2 mediates the caspase-1-dependent death of intestinal epithelial cells and bone marrow cells in response to double-strand DNA breaks caused by ionizing radiation and chemotherapeutic agents. Mechanistically, we found that AIM2 senses radiation-induced DNA damage in the nucleus to mediate inflammasome activation and cell death. Our results suggest that AIM2 may be a new therapeutic target for ionizing radiation exposure

Mink is a highly susceptible host species to circulating human and avian influenza viruses

Pandemic influenza, typically caused by reassortment of human and avian influenza viruses, can result in severe or fatal infections in humans. Timely identification of potential pandemic viruses must be a priority in influenza virus surveillance. However, the range of host species responsible for the generation of novel pandemic influenza viruses remain unclear. In this study, we conducted serological surveys for avian and human influenza virus infections in farmed mink and determined the susceptibility of mink to prevailing avian and human virus subtypes. The results showed that farmed mink were commonly infected with human (H3N2 and H1N1/pdm) and avian (H7N9, H5N6, and H9N2) influenza A viruses. Correlational analysis indicated that transmission of human influenza viruses occurred from humans to mink, and that feed source was a probable route of avian influenza virus transmission to farmed mink. Animal experiments showed that mink were susceptible and permissive to circulating avian and human influenza viruses, and that human influenza viruses (H3N2 and H1N1/pdm), but not avian viruses, were capable of aerosol transmission among mink. These results indicate that farmed mink could be highly permissive “mixing vessels” for the reassortment of circulating human and avian influenza viruses. Therefore, to reduce the risk of emergence of novel pandemic viruses, feeding mink with raw poultry by-products should not be permitted, and epidemiological surveillance of influenza viruses in mink farms should be urgently implemented

N-linked glycosylation enhances hemagglutinin stability in avian H5N6 influenza virus to promote adaptation in mammals

Clade 2.3.4.4 avian H5Ny viruses, namely H5N2, H5N6, and H5N8, have exhibited unprecedented intercontinental spread in poultry. Among them, only H5N6 viruses are frequently reported to infect mammals and cause serious human infections. In this study, the genetic and biological characteristics of surface hemagglutinin (HA) from clade 2.3.4.4 H5Ny avian influenza viruses (AIVs) were examined for adaptation in mammalian infection. Phylogenetic analysis identified an amino acid (AA) deletion at position 131 of HA as a distinctive feature of H5N6 virus isolated from human patients. This single AA deletion was found to enhance H5N6 virus replication and pathogenicity in vitro and in mammalian hosts (mice and ferrets) through HA protein acid and thermal stabilization that resulted in reduced pH threshold from pH 5.7 to 5.5 for viral-endosomal membrane fusion. Mass spectrometry and crystal structure revealed that the AA deletion in HA at position 131 introduced an N-linked glycosylation site at 129 which increases compactness between HA monomers thus stabilizes the trimeric structure. Our findings provide a molecular understanding of how HA protein stabilization promotes cross-species avian H5N6 virus infection to mammalian hosts

Prevalent Eurasian avian-like H1N1 swine influenza virus with 2009 pandemic viral genes facilitating human infection

Pigs are intermediate hosts for the generation of pandemic influenza virus. Thus, systematic surveillance of influenza viruses in pigs is a key measure for prewarning the emergence of the next pandemic influenza. Here, we identified a reassortant EA H1N1 virus possessing pdm/09 and TR-derived internal genes, termed as G4 genotype, which has become predominant in swine populations since 2016. Similar to pdm/09 virus, G4 viruses have all the essential hallmarks of a candidate pandemic virus. Of concern is that swine workers show elevated seroprevalence for G4 virus. Controlling the prevailing G4 EA H1N1 viruses in pigs and close monitoring in human populations, especially the workers in swine industry, should be urgently implemented.Pigs are considered as important hosts or “mixing vessels” for the generation of pandemic influenza viruses. Systematic surveillance of influenza viruses in pigs is essential for early warning and preparedness for the next potential pandemic. Here, we report on an influenza virus surveillance of pigs from 2011 to 2018 in China, and identify a recently emerged genotype 4 (G4) reassortant Eurasian avian-like (EA) H1N1 virus, which bears 2009 pandemic (pdm/09) and triple-reassortant (TR)-derived internal genes and has been predominant in swine populations since 2016. Similar to pdm/09 virus, G4 viruses bind to human-type receptors, produce much higher progeny virus in human airway epithelial cells, and show efficient infectivity and aerosol transmission in ferrets. Moreover, low antigenic cross-reactivity of human influenza vaccine strains with G4 reassortant EA H1N1 virus indicates that preexisting population immunity does not provide protection against G4 viruses. Further serological surveillance among occupational exposure population showed that 10.4% (35/338) of swine workers were positive for G4 EA H1N1 virus, especially for participants 18 y to 35 y old, who had 20.5% (9/44) seropositive rates, indicating that the predominant G4 EA H1N1 virus has acquired increased human infectivity. Such infectivity greatly enhances the opportunity for virus adaptation in humans and raises concerns for the possible generation of pandemic viruses