Search

Antibiotics on H2 producing bacteria shall be considered as being one of the critical elements in biological H2 production utilizing livestock manure as raw resources. Despite the fact that the manure stands a significance role in bio-fermentation, the possibility of antibiotics being contained in excreta shall not be eliminated. Findings of whether the above saying might threaten the safety of bio-H2 production needs to be further studied. The experiment subjects include: six single and three combined antibiotics were tested and analyzed by the application of the gradient experiment method. Along with the H2 production rate, CHO content, pH and OD600 were used to analyze the effects of various antibiotics introduction on the hydrolysis, fermentation and H2 production. To a further extent, four typical representative samples were selected for biodiversity analysis from the single antibiotic experiment groups. Amounting more than 6000 pieces of data were obtained in a series of experiments. Data suggested that remarkable measure of antibiotics have various degrees of H2 production inhibition, while some antibiotics, Penicillin G, Streptomycin Sulfate, and their compound antibiotics, could promote the growth of Ethanoligenens sp. and improve H2 yield in the contrary. Correspondent to the transition of key metabolic intermediates and end products, the mechanism of each antibiotic type and dose on H2 production were summarized as follows: the main inhibitory mechanisms were: (1) board-spectrum inhibition, (2) partial inhibition, (3) H2 consumption enhancement; and the enhancement mechanisms were: (1) enhance the growth of H2-producing bacteria, (2) enhanced starch hydrolysis, (3) inhibitory H2 consumption or release of acid inhibition. Meanwhile, data analysis found that the effect of antibiotics on H2 producing was not only related to type, but also to dosage. Even one kind of antibiotic may have completely opposite effects on H2-producing bacteria under different dosage conditions. Inhibition of H2 yield was highest with Levofloxacin at 6.15 mg/L, gas production was reduced by 88.77%; and enhancement of H2 yield was highest with Penicillin G at 7.20 mg/L, the gas production increased by 72.90%.

The microstructures and morphologies of directionally solidified Ti–47Al alloys with different growth rates ranging from 1 to 200 μm/s were investigated using the Bridgman directionally solidified method. The results showed that numerous columnar grains were formed along the growth direction with the onset of directional solidification. With a variation in the growth rate, the solid/liquid interface changed from a flat to cellular and to dendritic interface. The flat-to-cellular interface transition rate of the Ti–47Al alloy varied from 1 to 3 μm/s. When the growth rate was higher than 10 μm/s, the solid/liquid interface showed typical dendritic growth. During the directional solidification process, the main phase of the directionally solidified Ti–47Al alloy was the α phase, which can be attributed to the solute segregation, supercooling of the components, and contamination of the alloy melt by the Y2O3 ceramic shell. After reaching the steady growth state during the directional solidification process, the solidification path of the alloy was: L→α→α+γ→(α2+γ) + γ. With an increase in the growth rate, the primary dendrite spacing (λ) and lamellar spacing (λs) of the alloy decreased gradually.

Since AA2060-T8 was introduced in the past few years, investigating the mechanical response, fracture mechanisms, and anisotropic behaviour of AA2060-T8 sheets under high strain rate deformation has been crucial. Thus, uniaxial tensile tests were performed under quasi-static, intermediate, and high strain rate conditions using universal testing machines as well as split Hopkinson tensile bars. The experimental results showed that the ductility of AA2060-T8 sheets was improved during high strain rate deformation because of the adiabatic softening and the inertia effect which contribute to slow down the necking development, and these results were verified by the fracture morphologies of high strain rate tensile samples. Furthermore, the strain rate hardening influence of AA2060-T8 was significant. Therefore, the Johnson–Cook constitutive model was modified to consider the effects of both strain and strain rates on the strain hardening coefficient. The results obtained from the improved Johnson–Cook constitutive model are in remarkable accordance with those obtained from experimental work. Thus, the improved Johnson–Cook model can predict the flow behavior of AA2060-T8 sheets at room temperature over a wide range of strain rates. The results of the present study can efficiently be used to develop a new manufacturing route based on impact hydroforming technology (IHF) to manufacture sound thin-walled-complex shape components from AA2060-T8 sheets at room temperature. Keywords: AA2060, High strain rate deformation, Dynamic behavior, Anisotropic response, Phenomenological-based constitutive modelling

Al-Li alloys are attractive for military and aerospace applications because their properties are superior to those of conventional Al alloys. Their exceptional properties are attributed to the addition of Li into the Al matrix, and the technical reasons for adding Li to the Al matrix are presented. The developmental history and applications of Al-Li alloys over the last few years are reviewed. The main issue of Al-Li alloys is anisotropic behavior, and the main reasons for the anisotropic tensile properties and practical methods to reduce it are also introduced. Additionally, the strengthening mechanisms and deformation behavior of Al-Li alloys are surveyed with reference to the composition, processing, and microstructure interactions. Additionally, the methods for improving the formability, strength, and fracture toughness of Al-Li alloys are investigated. These practical methods have significantly reduced the anisotropic tensile properties and improved the formability, strength, and fracture toughness of Al-Li alloys. However, additional endeavours are required to further enhance the crystallographic texture, control the anisotropic behavior, and improve the formability and damage tolerance of Al-Li alloys.

The ultrasonic-assisted soldering joint of Cu/Al with different contents of copper particles added to solder powder at low temperature was studied. In this study, 15%SAC0307 solder powder with a diameter of 500 nm, different amounts copper particles with a diameter of 500 nm were mixed with zinc particles of a diameter of 45 μm to fill the Cu/Al joint, and the soldered was heated to 240 °C for ultrasonic-assisted under the environmental atmosphere. Successfully achieved micro-joining of Cu/Al under ultrasonic-assisted at low-temperature. The results have shown that, when the copper content was 0%-15%, two layers of complete and continuous CuxZny compounds were formed at the copper side interface. When the copper content was more than 15%, the IMC layer of the copper side interface was not obvious, and a large amount of CuxZny compounds were formed near the copper side. The base metals on the aluminum side formed a solid solution combination with zinc. When the addition amount of copper powder was 15%, the soldering seam was smooth and flat, the defect between balls was not obvious, and the IMC was uniformly distributed, so the average shear strength reached the maximum value of 47.37 MPa.