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To improve mechanical and thermal properties of jute fibers (JFs) reinforced polypropylene (PP) composites, a surface treatment method by grafting graphene oxide nanoplatelets (GONPs) onto JFs was developed. The GONPs effectively enhanced the interfacial adhesion between JFs and PP matrix via improving mechanical interlocking. The results show that PP/JFs-KH570-GONPs composites had the significant improvement of 16.2 % and 12.4 % in tensile and flexural strength, respectively. And the thermal property of PP/JFs-Silane-GONPs composites was also improved after treatment. These high performance composites have the potential to be applied in many fields, such as the automotive industry, household products and so on.

Vibrio splendidus is the main opportunistic pathogen that causes skin ulcer syndrome in Apostichopus japonicus. hppDIn the present study, mutant V. splendidus with an in-frame deletion of hppDV.s. (MTVs) was constructed. The median lethal doses of wild-type V. splendidus (WTVs) and MTVs were 5.129 × 106 and 2.606 × 1010 CFU mL−1, respectively. RNA-Seq was performed using WTVs and MTVs cells at different growth stages to explore the mechanisms of the pathogenesis mediated by hppDV.s. Gene Ontology analysis showed that the expression levels of 105 genes involved in amino acid metabolism and protein binding were remarkably different between MTVs and WTVs. Kyoto Encyclopedia of Genes and Genomes analysis showed that the pathways of glutamate metabolism and flagellum assembly involved in biofilm formation and swarming motility were suppressed in MTVs. Correspondingly, the swarming motility, biofilm formation and colonisation of MTVs were remarkably decreased compared with those of WTVs. The results showed that 4-hppD catalyses tyrosine into fumarate, which could enhance glutamate metabolism and ATP production; promote flagellum assembly through the TCA cycle and lead to higher swarming, biofilm formation and colonisation abilities, to contribute to the pathogenesis of V. splendidus.

To address deficiencies in traditional coating and adhesive processes for installing auto safety glasses, mounting brackets for auto safety glass were formed by the insert injection molding...

The Al-Si coating of ultra-high strength steel has been applied to hot stamping more and more widely, owing to solving the problem of oxidation and decarburization. However, the evolution of Al-Si coating during the heating process was rarely studied in the previous study. The tests about the influence of heating parameters, such as heating temperature, heating rates and dwell time, on properties of the Al-Si coating were carried out on the Gleeble-3500 thermal simulator. The properties of the Al-Si coating, for instance, volume fraction of FeAl intermetallics, α-Fe layer as well as porosity and 3D surface topography, were explored in the study. Results showed that more and more Kirkendall voids and cracks appeared in the Al-Si coating when the heating temperature exceeded 600°C. The heating rates almost had no influence on properties of the Al-Si coating when the temperature was equal to or lower than 500°C. The volume fraction of FeAl intermetallics in the coating with dwell time from 3 s to 8 min at 930°C was 0, 6.19%, 17.03% and 20.65%, separately. The volume fraction of the α-Fe layer in the coating changed from zero to 31.52% with the prolonged dwell time. The porosity of the coating ranged from 0.51% to 4.98% with the extension of dwell time. The unsmooth degree of the surface of the coating rose gradually with the increasing of heating rates and the extension of dwell time. The 3D surface topography of the coating was determined by the comprehensive effect of atoms diffusion, new formed phases, surface tension and the degree of oxidation of the coating surface. Experiments indicated that rapid heating was not suitable for the coating when the temperature exceeded 500°C. Experiments also demonstrated that enough dwell time was essential to obtain the superior properties of the coating.

In this study, a thermo-plastic-martensite transformation coupled model based on the von Mises yield criterion and the associated plastic flow rule is developed to further improve the accuracy of numerical simulation during hot stamping. The constitutive model is implemented into the finite element program ABAQUS using user subroutine VUMAT. The martensite transformation, transformation-induced plasticity and volume expansion during the austenite-to-martensite transformation are included in the constitutive model. For this purpose, isothermal tensile tests are performed to obtain the flow stress, and non-isothermal tensile tests were carried out to validate the constitutive model. The non-isothermal tensile numerical simulation demonstrates that the thermo-plastic-martensite transformation coupled constitutive model provides a reasonable prediction of force-displacement curves upon loading, which is expected to be applied for modeling and simulation of hot stamping.

Vibrio splendidus is an important opportunistic pathogen that can infect a broad range of aquatic animals including Apostichopus japonicus, leading to skin ulceration syndrome. In this study, fur gene of V. splendidus (furVₛ), the gene encoding ferric uptake regulator (Fur) of V. splendidus, was cloned and characterized. furVₛ possessed the signature ammonia acids of Vibrio sp., and its mRNA level was regulated by iron and coelomic fluid of A. japonicus. While the amino acid sequence of the furVₛ showed high homology with the compared Fur proteins of other Vibrio sp., the nucleotide sequence of furVₛ differed greatly from that of the other fur genes from Vibrio sp., based on which a pair of specific primers VSFurRTF3 and VSFurRTR3, was designed. A distinct DNA band with a length of 223 bp can be amplified from V. splendidus with great specificity. The detection limits for V. splendidus in seawater, homogenized tissues of epidermis, muscles, and coelomic fluid from A. japonicus, was 1 × 10², 1 × 10⁵, 1 × 10³, and 1 × 10² CFU/mL, respectively. Moreover, the detection limit was as low as 8 × 10⁻³ pg/μL when using DNA of V. splendidus as a template. Our results provide a simple and rapid polymerase chain reaction method for the sensitive and specific detection of V. splendidus.

In this work, the surface of the bamboo fibers (BF) was treated with three kinds of silane coupling agents terminated with amino functional groups (KH550), epoxy functional groups (KH560), and methyl functional groups (KH570) to improve fiber–matrix adhesion. The effects of silane treatment on the mechanical properties and thermal behavior of BF/polypropylene (PP) composites were investigated. Mechanical test results showed that the order of modification effectiveness was KH570 > KH550 > KH560. KH570 treated fiber composite exhibited the best mechanical properties. The tensile strength and flexural strength of 5 wt% KH570 treatment reached to 36.1 and 54.7 MPa, which were 15.4% and 23.6% higher than those of UBF/PP composites. Simultaneously, the thermal stability increased from 467.0°C (UBF) to 470.6°C (KH-570 treated BF). An increase in crystallization temperature (1.7°C) and a decrease in crystallinity (5.8%) occurred upon the addition of 5% KH570 silanes treated bamboo fibers.

In traditional hot stamping process, heating of the sheet by radiation heating occupies most of cycle time, which limits the application of hot stamping in automotive industry. Thus a faster heating method has great significance on the hot stamping. The conduction heating overcomes shortage of the radiation heating because of higher heating rate and greater energy efficiency. It attracts increasing attention in the application of heating blanks in hot stamping. In the present study, a movable conduction heating device on die was designed in terms of the Joule’s Law. Heating experiments of boron alloyed steel were performed using the developed device. Heating rate and uniform temperature region were investigated in the non-heat preservation condition (NHPC) and the heat preservation condition (HPC). The results revealed that in the HPC, the heating rate was improved by 13.1 °C/s. In addition, the length of the uniform temperature region was lengthened by 15 mm. It was demonstrated that the HPC was preferred. Furthermore, it was indicated that the mechanical properties of the blanks in uniform temperature region of the conduction heating were also superior to that of the radiation heating.

In this study, austenitizing heat treatment before hot stamping of Al-10% Si coated boron steel is first investigated through environment scanning electron microscopy (ESEM) equipped with energy dispersive x-ray analysis (EDAX). The cracking behavior of the coating was evaluated using Gleeble 3500, a thermo-mechanical simulator under uniaxial plastic deformation at elevated temperatures. The extent and number of cracks developed in the coating were carefully assessed through an optical microscope. The coating layer under hot-dipped condition consists of an Al-Si eutectic matrix, Fe2Al7Si, Fe3Al2Si3 and Fe2Al5, from the coating surface to the steel substrate. The coating layer remains dense, continuous and smooth. During austenitization, the Al-rich Fe-Al intermetallics in the coating transform to more Fe-rich intermetallics, promoted by the Fe diffusion process. The coating finally shows the coexistence of two types of Fe-Al intermetallics, namely, FeAl2 and FeAl. Microcracks and Kirkendall voids occur in the coating layer and diffusion zone, respectively. The coating is heavily cracked and broken into segments during the hot tensile tests. Bare steel exposed between the separate segments of the coating is oxidized and covered with a thin FeO x layer. The appearance of the oxide decreases the adhesion of the Al-Si coating. It is found that the ductile FeAl is preferred as a coating microstructure instead of the brittle FeAl2. Therefore, the ductility of the Al-Si coating on hot stamping boron steel could be enhanced by controlling the ductile Fe-rich intermetallic phase transformations within it during austenitization. Experiments indicate that a higher austenitizing temperature or longer dwell time facilitate the Fe-rich intermetallics transformation, increasing the volume fraction of FeAl. This phase transformation also contributes to reducing the crack density and depth.

Hot tensile tests of boron steels with and without an Al–Si coating were performed using a Gleeble 3500 test system, at temperatures of 700–850 °C and strain rates of 0.01–1/s. The phase and microstructure of the coating in as-coated and press-hardened conditions were observed under scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis and X-ray diffraction (XRD). Experimental results indicate that the Al–Si coating gave an unignorable influence on the thermo-mechanical properties of the boron steels. The ultimate tensile strength (UTS) of the Al–Si coated boron steel was almost equal to that of the uncoated under the lower strain rate at the same deformation temperature. At a higher strain rate, the UTS value appeared to be lower than that of the uncoated. Moreover, the UTS difference increased with the decreasing deformation temperature. The ductility of the Al–Si coated steel was lower than that of the uncoated under the described test conditions. Following the tensile tests, extensive cracks were visible in the Al–Si coating layer. SEM observation showed that microcracks and voids appeared after austenization, which may act as nucleation sites for the cracks. The cracks first propagated in the direction perpendicular to the coating/substrate interface and were identified as Type I cracks. The propagation was hindered by the substrate when these cracks reached the coating/substrate interface. This occurred because the interfacial bonding strength between the coating and the substrate was lower than the substrate strength. Following this initial failure, the cracks turned to propagate paralleled to the coating/substrate interface. In addition with the shear stress resulting from the substrate yielding, Type II cracks formed. Eventually, the cracked coatings were accompanied by interface decohesion from the substrate. The width and density of the cracks were found to increase with the decreasing deformation temperature and rising stain rate.