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The membrane-proximal external region (MPER) is a promising HIV-1 vaccine target owing to its linear neutralizing epitopes and highly conserved amino acids. Here, we explored the neutralization sensitivity and investigated the MPER sequences in a chronic HIV-1 infected patient with neutralizing activity against the MPER. Using single-genome amplification (SGA), 50 full-length HIV-1 envelope glycoprotein (env) genes were isolated from the patient's plasma at two time points (2006 and 2009). The neutralization sensitivity of 14 Env-pseudoviruses to autologous plasma and monoclonal antibodies (mAbs) was evaluated. Env gene sequencing revealed that the diversity of Env increased over time and four mutation positions (659D, 662K, 671S, and 677N/R) were identified in the MPER. The K677R mutation increased the IC50 values of pseudoviruses approximately twofold for 4E10 and 2F5, and E659D increased the IC50 up to ninefold for 4E10 and fourfold for 2F5. These two mutations also decreased the contact between gp41 and mAbs. Almost all mutant pseudoviruses were resistant to autologous plasma at both the earlier and concurrent time points. Mutations 659D and 677R in the MPER decreased the neutralization sensitivity of Env-pseudoviruses, providing a detailed understanding of MPER evolution which might facilitate advances in the design of HIV-1 vaccines. [ABSTRACT FROM AUTHOR]

In the present study, the mechanical behaviors and microstructural evolution of the nickel-based superalloy FGH97 at different temperatures and strain rates were studied. First, the tensile tests were conducted at temperatures of 20 °C, 450 °C and 700 °C, respectively, at two specified strain rates of 0.00025 s–1 and 0.001 s–1. Second, the microscopic observations of the sections were carried out to analyze the microstructure feature. Based on the test data and the observations, it was found that the influence of strain rate on the deformation and elongation will be weakened at higher temperature. Furthermore, the phenomenon of stress serrations and the intermedia temperature brittleness were just observed at 450 °C, and the reason for that was investigated. [ABSTRACT FROM AUTHOR]

With the improvement of inlet temperature of aero-engine turbine, continuous fiber reinforced ceramic matrix composite (CFCC) has become an important material for turbine guide vane. In this paper, the testing method of steady state thermal load and cyclic thermal load were explored under typical working environment of turbine guide vane. The temperature field was established through the high-frequency induction heating and was measured by thermocouples and an infrared thermometer. The DIC strain gauge was used to measure the strain. This method overcomes the difficulties in the temperature field establishment, temperature and strain measurements of the ceramic matrix composites. The material mapping method has been applied to calculate the macroscopic stress and strain. It has been observed that the maximum strain error was 11.8% compared with the steady state thermal load experiment result. On this basis, the stress and strain of the thermal fatigue load were analyzed. In addition, a fatigue test was carried out on the standard test pieces, which had the same manufacturing process with the turbine vane. The obtained results through this paper show that the life of the vane was more than 8.34 × 106 under the thermal fatigue load. The experimental and numerical calculation methods proposed in this study provide the experimental and theoretical basis for further research. [ABSTRACT FROM AUTHOR]

We present a monolithic Lagrangian meshfree solution for Fluid–Structure Interaction (FSI) problems within the Optimal Transportation Meshfree (OTM) framework. The governing equations of the fluid and structure are formulated in the Lagrangian configuration and solved simultaneously in a monolithic way. Mainly, the fully discretized equations are constructed by leveraging on the OTM method to address the challenges in the Lagrangian description of the fluid domain. In this approach, the fluid–structure interface becomes an internal surface of the entire field, and the continuity and force equilibrium on the interface are automatically satisfied without any extra computations. The monolithic Lagrangian solution provides enhanced stability comparing to partitioning approaches and eliminates the problem of free surface and material interface tracking. The presented method enables a Direct Numerical Simulation (DNS) of the fluid flow with the absence of the convective terms. The accuracy and robustness of the OTM FSI approach are systematically investigated by the classical Blasius solution of the boundary layer problem. Furthermore, we illustrate the range and scope of the method through two examples: the impact of a rigid body on the fluid domain in a container and the interaction between the fluid and highly flexible structures in an open channel. [ABSTRACT FROM AUTHOR]