Search

The winding tension of the dry-wound forming process is uniform, the process is easy to control and the structure and performance of the prepared vehicle-mounted hydrogen composite pressure vessels are stable. Since the vehicle-mounted hydrogen pressure vessels must be subjected to rigorous fire experiments, the flame-retardant epoxy prepreg yarn technology is currently monopolized by foreign countries. The development of flame-retardant prepreg yarn with good processing properties is of great significance to the promotion and application of hydrogen pressure vessels. Here, a flame-retardant additive hexaphenoxy cyclotriphosphazene (HPCTP) was synthesized and dissolved in epoxy resin of prepreg yarn named P/N-EP. Then, the flame-retardant prepreg yarn was made by the solution impregnation method. Curing behavior, thermal analysis combustion behavior and mechanical properties of P/N-EP and tensile properties of flame-retardant prepreg yarn were investigated. Experimental results showed that the LOI value reached 36.4% at 10 phr and reached the V-0 level of the UL-94 test. The results about thermal stability of the P-N/EP resin system showed that with the increase of P-N content, T5% (temperature at 5% weight loss) and CY600 (carbon residue rate) both increased. The microstructure of carbon residue after UL-94 test was studied by electron microscope and laser Raman spectrometer. The results showed that with the increase of P-N content, the carbon layer structure became denser and the ID/IG decreased significantly, to achieve the flame-retardant effect by the condensed phase mechanism. [ABSTRACT FROM AUTHOR]

Large tow carbon fiber (LTCF) has excellent performance and low cost. However, there are still many difficulties in the application of LTCFs, among which the problem of interfacial penetration is mainly solved. Building interfaces with sizing structures of fiber composites is an effective approach to achieve high performance. In this article, a water-based epoxy sizing agent suitable for LTCF fiber thermoset composites was studied. A comparison of the five LTCFs in this study shows that the wettability and contact angle of the sized LTCFs are significantly improved. In addition, the interfacial shear strength (IFSS) and interlaminar shear strength (ILSS) increased from 52.3 to 71.0 MPa (35%) and 36.4 to 54.6 MPa (50%), respectively. Compared with other imported LTCFs, domestic large-size LTCFs have a wide variety and a large number of surface functional groups, thereby improving their wettability and covalent bonding with the resin matrix. This work has reference significance for the practical application and industrial production of LTCFRP. [ABSTRACT FROM AUTHOR]

This article presents the ride comfort and handling stability performance of an articulated dumper truck (ADT). Considering the influence of the hydropneumatic suspension (HPS) with gas–oil emulsion on the ADT, a comprehensive ADT dynamic model is proposed. Also, on the basis of the nonlinear programming quadratic line (NLPQL) algorithm, an integrated multi-objective optimization method regarding the HPS with gas–oil emulsion is proposed to improve the comfort and stability and ensure enough suspension working space. The body acceleration, roll angle and pitch angle of HPS are optimized to a higher degree by 17.2%, 18.4% and 23% (with no load) and 18.3%, 17.7% and 23.1% (with full load) under random excitation input. The simulation results show that the NLPQL optimization method not only increases the ride comfort and handling stability performance of ADT with reasonable suspension working space, but also helps to guide the design of the ADT's HPS system. [ABSTRACT FROM AUTHOR]

Immunoglobulins are affected by sex, age and region, so it is necessary to establish suitable reference intervals (RIs) for clinical diagnosis. Various statistical methods were used to calculate RIs, but there has been a lack of comparison among the methods. Research based on immunoglobulin RIs establishment with various methods would provide a methodological basis for further research. A total of 16,525 individuals were enrolled in the study. Individuals were selected in the medical examination center of First Hospital of Jilin University from 2014 to 2020. The lambda-mu-sigma (LMS) method was performed to evaluate the dynamic changes in analytes. RIs were calculated by parametric, non-parametric, Hoffman method and Bhattacharya method. Sex and age partitions were found for immunoglobulins G and immunoglobulin M. The levels of IgM showed no difference with age in males, but showed differences after 50 years of age in females. Circulating immunoglobulin A concentrations showed an increasing trend with age, and immunoglobulin M showed a fluctuating trend with age. Obvious difference (>5%) was commonly found among the four methods, however, the RIs established by the four methods all passed the verification with a high passing rate. Sex and age differences should be considered for immunoglobulins G and immunoglobulin M in clinical practice. The feasibility of the four indirect methods was proven, which would provides a methodological reference for further studies and benefit the application of clinical data. [ABSTRACT FROM AUTHOR]

The road condition is complex and variable during driving; hence, the suspension system cannot easily suppress the vertical vibration of the vehicle. To effectively improve the vehicle dynamic performance under different road conditions, this study proposes a switching control strategy for the semi-active suspension based on the road profile estimation. First, the mapping relationship between different driving conditions and requirements of vehicle dynamic performances is studied. Then, a switching controller with multiple sub-controllers is designed on the basis of the modified skyhook control. The optimal control gains are obtained by adopting the cuckoo search algorithm. In addition, to realise the automatic switching of the controller under different road conditions, an online road profile estimation method, including road disturbance estimation and road roughness classification, is developed. Bench test results show that the proposed control algorithm has an obvious effect on improving the vehicle ride comfort and handling performance, which verifies the effectiveness of the road estimation results and the superiority of the switching control strategy. [ABSTRACT FROM AUTHOR]

The community-associated Methicillin-resistant Staphylococcus aureus strain (CA-MRSA) is highly virulent and has become a major focus of public health professionals. Phenol-soluble modulins (PSM) are key factors in its increased virulence. δ-Toxin belongs to PSM family and has copious secretion in many S. aureus strains. In addition, δ-toxin exists in the S. aureus culture supernatant as both N-terminus formylated δ-toxin (fδ-toxin) and deformylated δ-toxin (dfδ-toxin) groups. Although δ-toxin has been studied for more than 70 years, its functions remain unclear. We isolated and purified PSMs from the supernatant of S. aureus MW2, and found fibrils and oligomers aggregates by Size Exclusion Chromatography. After analyzing PSM aggregates and using peptide simulations, we found that the difference in the monomer structure of fδ-toxin and dfδ-toxin might ultimately lead to differences in the aggregation ability: fδ-toxin and dfδ-toxin tend to form fibrils and oligomers respectively. Of note, we found that fδ-toxin fibrils enhanced the stability of biofilms, while dfδ-toxin oligomers promoted their dispersal. Additionally, oligomeric dfδ-toxin combined with PSMα to form a complex with enhanced functionality. Due to the different aggregation capabilities and functions of fδ-toxin and dfδ-toxin, we speculate that they may be involved in the regulation of physiological activities of S. aureus. Moreover, the dfδ-toxin oligomer not only provides a new form of complex in the study of PSMα, but also has significance as a reference in oligomer research pertaining to some human amyloid diseases. [ABSTRACT FROM AUTHOR]