Influence of Huangqin Decoction on the immune function and fecal microbiome of chicks after experimental infection with Escherichia coli O78.

Huangqin Decoction (HQD), a traditional Chinese medicine formula from the Shang Han Lun written by Zhang Zhongjing, has been used in China for nearly two thousand years. According to the traditional Chinese medicine and previous literature, HQD has the effect of clearing heat, removing toxins, relieving diarrhea and pain. Therefore, HQD was used to prevent or cure many diseases, such as inflammation, diarrhea, malaria, and other acute or chronic gastrointestinal diseases. The effect of HQD, one-herb-absent HQD treatments and enrofloxacin (ENR) on the average daily gain (ADG), mortality rates, visceral index and toll-like receptors (TLRs), inflammatory factors and intestinal microflora in E. coli O78-inoculated chicks were investigated. HQD supplementation increased ADG and reduced the mortality rates caused by E. coli challenge, decreased the heart, liver, bursa of Fabricius (BF) and spleen index. HQD supplementation decreased the serum lysozyme (LZM), IL-1ß, TNF-α, IL-10, IL-6 level, down-regulated the mRNA expression of TLR4, -5 and -15 in the spleen by E. coli challenged chicks, and up-regulated the mRNA expression of TLR4, -5 and -15 in BF. At the phylum level, HQD supplementation reversed the increase of Operational Taxonomic Unit (OTUs), decreased the relative abundance of harmful bacteria Proteobacteria, increased the relative abundance of probiotic bacteria Bacteroidetes and Firmicutes. At the genus level, HQD decreased the relative abundance of harmful bacteria Escherichia-Shigella and Pseudomonas. It means that HQD treatment reversed the change of the gut microbiota structure. Compared with HQD, HQD-DZ and HQD-HQ increased the mortality rates. HQD-HQ decreased the ADG and liver index. HQD-GC decreased the spleen index. All herb-absent increased the serum IL-6, but only the HQD-HQ and HQD-SY increased the serum TNF-α. All herb-absent did not activate the TLRs signaling pathways in spleen and BF of chicks. The harmful bacteria Escherichia-Shigella were increased in HQD-HQ and HQD-DZ treatments. HQD-DZ treatment also increased the level of Proteobacteria. The results showed that dietary supplementation with HQD, by down-regulating the mRNA expression of TLR4, -5 and -15 in the spleen, further decreasing the serum LZM and IL-1ß, TNF-α, IL-10, IL-6 level, improves the immune function and reverses the change of fecal microbiome in chicks challenged with E. coli. In herb-absent supplementation, the results showed that SY and DZ play a key role in reducing the levels of inflammatory factors and keeping fecal microbiome balance respectively. More importantly, HQ is indispensable in HQD, not only play a key role in reducing the level of inflammatory factors, but also in keeping the balance of fecal microflora.

Wide-Gap Brazing of K417G Alloy Assisted by In Situ Precipitation of M3B2 Boride Particles.

In this study, K417G Ni-based superalloy with a 20-mm gap was successfully bonded at 1200 °C using powder metallurgy with a powder mixture. The results indicated that the microstructure and mechanical properties of the as-bonded alloy were highly dependent on the brazing time (15-45 min), mainly due to the precipitation and distribution characteristics of M3B2 boride particles. Specifically, alloy brazed for 30 min exhibited desirable mechanical properties, such as a high tensile ultimate strength of 971 MPa and an elongation at fracture of 6.5% at room temperature, exceeding the balance value (935 MPa) of the base metal. The excellent strength and plasticity were mainly due to coherent strengthening and dispersion strengthening of the in situ spherical and equiaxed M3B2 boride particles in the γ + γ' matrix. In addition, the disappearance of dendrites and the homogenization of the microstructure are other factors that cannot be excluded. This powder metallurgy technique, which can avoid the eutectic transformation of traditional brazing, provides a new effective method for wide-gap repair of alloy materials.

Influence of Effective Laser Energy on the Structure and Mechanical Properties of Laser Melting Deposited Ti6Al4V Alloy.

The laser energy density (ED) is often utilized in many additive manufacturing (AM) processes studies to help researchers to further investigate the process-structure-property correlations of Ti6Al4V alloys. However, the reliability of the ED is still questionable. In this work, a specific empirical calculation equation of the effective laser energy (Ee), which is a dimensionless parameter in laser melting deposition (LMD) processing, was proposed based on the molten pool temperature. The linear regression results and the coefficient of determination prove the feasibility of the Ee equation, which indicates that Ee can more accurately reflect the energy-temperature correlations than the commonly used laser energy density (ED) equation. Additionally, Ti6Al4V components were fabricated by the LMD process with different Ee to investigate the influence of Ee on their structure and mechanical properties. Experimental results show that the detrimental columnar prior ß meso-structure can be circumvented and the uniform α + ß laths micro-structure can be obtained in LMD Ti6Al4V by a judicious combination of the process parameter (P = 2000 W, V = 12 mm/s, and F = 10.5 g/min) and Ee (7.98 × 105) with excellent tensile strength (1006 ± 25 MPa) and elongation (14.9 ± 0.6%). Overall, the present work provides an empirical calculation equation to obtain a clearer understanding of the influence of different process parameters and indicates the possibility to fabricate the Ti6Al4V alloy with excellent mechanical properties by parameter optimization in the LMD process.

Study on Microstructure and Mechanical Properties of WC-10Ni3Al Cemented Carbide Prepared by Different Ball-Milling Suspension.

In this paper, WC-10Ni3Al cemented carbides were prepared by the powder metallurgy method, and the effects of ball-milling powders with two different organic solvents on the microstructure and mechanical properties of cemented carbides were studied. We show that the oxygen in the organic solvent can be absorbed into the mixed powders by ball-milling when ethanol (CH3CH2OH) is used as a ball-milling suspension. This oxygen leads to the formation of α-Al2O3 during sintering, which improves the fracture toughness, due to crack deflection and bridging, while the formation of η-phase (Ni3W3C) inhibits the grain growth and increases the hardness. Alternatively, samples milled using cyclohexane (C6H12) showed grain growth during processing, which led to a decrease in hardness. Therefore, the increase of oxygen content from using organic solvents during milling improves the properties of WC-Ni3Al composites. The growth of WC grains can be inhibited and the hardness can be improved without loss of toughness by self-generating α-Al2O3 and η-phase (Ni3W3C).