Microstructural evolution in Al–Zn–Mg–Cu–Sc–Zr alloys during short-time homogenization

Abstract： Microstructural evolution in a new kind of aluminum （A1） alloy with the chemical composition of AI-8.82Zn-2.08Mg- 0.80Cu-3.31Sc-0.3Zr was investigated. It is found that the secondary phase MgZn2 is completely dissolved into the matrix during a short homogenization treatment （470℃, 1 h）, while the primary phase A13（Sc,Zr） remains stable. This is due to Sc and Zr additions into the A1 al- loy, high Zn/Mg mass ratio, and low Cu content. The experimental findings fit well with the results calculated by the homogenization diffusion kinetics equation. The alloy shows an excellent mechanical performance after the short homogenization process followed by hot-extrusion and T6 treatment. Consequently, a good combination of low energy consumotion and favorable mechanical properties is obtained.

Microstructural evolution and mechanical behavior of in situ synthesized MgAl_(2)O_(4)whiskers reinforced 6061 Al alloy composite after hot extrusion and annealing

In situ synthesized MgAl2O4whiskers reinforced 6061 Al alloy composites were fabricated by a powder metallurgy method.Nano-sized MgAl2O4spinel whiskers distributed uniformly in 6061 Al alloy matrix without any interfacial product and laid along the extrusion direction after hot extrusion.As-extruded composite samples were annealed at 530,580,600 and 630℃for 1 h and examined by electron backscattered diffraction to investigate the recrystallization behavior of obtained composites.Microstructure and texture evolution was investigated,and it is found that the recrystallization process is inhibited by whiskers because of Zener pinning.Slender fibrous grains remain until 630℃,and deformation textures still exist even in specimen annealed at 630℃.Hardness and tensile tests show that the completely recrystallized sample has an ultimate tensile strength of 218 MPa and a hardness of HV52 compared with 283 MPa and HV 69 of the unannealed sample.Mechanical properties of the annealed samples decline slightly with annealing temperature increasing up to 600℃.

A phytochemical study on Dichocarpum auriculatum, an endangered medicinal plant peculiar to China

Objective:Dichocarpum auriculatum,an endangered perennial herb,is endemic to China and has been used as folk medicines for the treatment of cough,hepatitis,scrofula,and epilepsy.However,there is no phytochemical report on this herbal so far.For the resource development and protective importance of this endangered medicinal plant,a phytochemical study was undertaken.Methods:The chemical constituents were purified by silica gel column,Sephadex LH-20 column,and semi-preparative reversed phase HPLC.NMR and MS spectra were used for structural identification.Results:Thirteen compounds were isolated from D.auriculatum.Their structures were characterized as jatrorrhizine(1),berberine(2),steponine(3),magnoflorine(4),coclauril(5),menisdaurin(6),menisdaurilide(7),aquilegiolide(8),(6 R,9 S)-3-oxo-α-ionol-β-D-glucopyranoside(9),blumenol C glucoside(10),palmitic acid(11),dibutylphthalate(12),and auriculatum A(13).Conclusion:Compound 13 is a new diester terephthalate derivative.All the compounds are obtained from the genus Dichocarpum for the first time,and compounds 9 and 10 have potential chemotaxonomic significance to the genus Dichocarpum.

Simultaneous determination of 15 flavonoids from different parts of Scutellaria baicalensis and its chemometrics analysis

Objective: The aerial parts of Scutellaria baicalensis were used as Huangqin Tea for thousands of years and mainly contain flavonoids which contribute to its bioactivities. However, there is no appropriate quality evaluation method of Huangqin Tea, and three flavanones of isocarthamidin-7-O-β-D-glucuronide,carthamidin-7-O-β-D-glucuronide, and isoscutellarein-8-O-β-D-glucuronide with high contents in the aerial parts have never been defined quantitatively. Here, an HPLC-DAD method for simultaneous determination of 15 flavonoids and systematically compared their contents and distribution in the roots,stems, leaves, and flowers of S. baicalensis was established.Methods: Under the HPLC-DAD chromatographic conditions, 77 batches of samples of S. baicalensis were analyzed. Meanwhile, the chromatographic fingerprint of different parts of S. baicalensis was established.Subsequently, principal component analysis(PCA), orthogonal projections to latent structures discriminant analysis(OPLS-DA), and clustering heat map were performed based on the contents of 15 flavonoids in different parts of S. baicalensis.Results: The results showed significant differences in the contents and distributions of 15 flavonoids among the different parts of S. baicalensis. The chemical composition of stems showed some similarities to leaves, and their contents were all lower than leaves. The contents of isocarthamidin-7-O-β–glucuronide [(106.66 66 ± 22.68) mg/g], carthamidin-7-O-β-D-glucuronide [(19.82 ± 11.17) mg/g],and isoscutellarein-8-O-β-D-glucuronide [(3.10 ± 1.73) mg/g] were the highest in leaves. The content of apigenin-7-O-β-D-glucopyranoside and chrysin-7-O-β-D-glucuronide were the highest in flowers. The contents of baicalin, baicalein, wogonoside, wogonin, alpinetin, and oroxylin A were higher in roots than in other parts.Conclusion: The method was fully validated and could be effectively used to characterize the contents and distributions of main flavonoids in the different parts of S. baicalensis. It may lay a foundation to establish the quality evaluation system for Huangqin Tea.

Carbon and few-layer MoS2 nanosheets co-modified TiO2 nanosheets with enhanced electrochemical properties for lithium storage

Carbon and few-layer MoS2 nanosheets co- modified TiO2 nanocomposites （defined as MoS2-C@TiO2） were prepared through a facile one-step pyrolysis reaction technique. In this unique nanostructure, the TiO2 nanosh- eets with stable structure serve as the backbones, and carbon coating and few-layer MoS2 tightly adhere onto the surface of the TiO2. It needs to be pointed out that the carbon coating improves the overall electronic conductivity and the few-layer MoS2 facilitates the diffusion of lithium ions and offers more active sites for lithium-ion storage. As a result, when evaluated as lithium-ion battery anodes, the MoS2-C@TiO2 nanocomposites exhibit markedly enhanced lithium storage capability compared with pure TiO2. A high specific capacity of 180 mA.h.g-1 has been achieved during the preliminary cycles, and the specific capacity can maintain 160 mA.h.g-1 at a high current density of 1C （1C=167 mA.g-1） even after 300 discharge/ charge cycles, indicating the great potential of the MoS2- C@TiO2 on energy storage.

Research on Quality Markers of Moutan Cortex: Quality Evaluation and Quality Standards of Moutan Cortex

Objective To identify the quality markers of Moutan Cortex（MC） and establish the quality evaluation methods for multi-component assay and fingerprinting of MC. Methods The chemical constituents in MC were identified by HPLC-QTOF-MS. UPLC was employed for the multi-component assay and fingerprinting of MC. Furthermore, text mining was carried out to review the biosynthesis pathways and pharmacological and pharmacokinetic studies related to MC, and in silico target fishing was conducted to construct compound-target networks for MC. Results Sixteen compounds were clearly identified in MC and their structures were confirmed through comparison with literature data. In addition, the biosynthetic pathways and component specificities of the identified compounds were summarized and confirmed by text mining.Pharmacological activities, including traditional usage and modern pharmacological studies were summarized. A total of 282 targets from Homo sapiens were fished for 13 compounds. In addition, pharmacokinetic studies of different compounds were synopsized. Finally, multi-component assay and fingerprint of MC were established. Conclusion Eight major components are selected as quality markers of MC, such as oxypaeoniflorin, apiopaeonoside, albiflorin, paeonolide, paeoniflorin, 1,2,3,4,6-penta-O-galloyl-β-D-glucose, mudanpioside C and paeonol. These eight quality markers are successfully applied to the quality evaluation of MC, and could be useful in improving the current quality standards of MC.

Microstructure and tensile properties of A356 alloy with different Sc/Zr additions

Addition of rare earth elements for improving the tensile properties of aluminum alloys has attracted great attention. In this study, a systematic analysis on the microstructure and tensile properties of A356–0.13 Ti alloys with different contents of scandium(Sc) and scandium/zirconium(Sc/Zr) after solution and aging treatment process was carried out. The addition of Sc/Zr into A356–0.13 Ti alloys can greatly refine the grain size and modify the deleterious coarse eutectic Si structure and harmful acicular iron-containing phase morphology. As a result, the maximum value of strength(298 MPa) and ductility(elongation of 8.4%) are acquired by co-addition of Sc/Zr after solution and aging treatment process, which indicates that the tensile properties of A356 alloy are greatly enhanced by the synergistic effect of co-addition of Sc/Zr.

Fabrication of Carbon Nanotube-Reinforced 6061Al Alloy Matrix Composites by an In Situ Synthesis Method Combined with Hot Extrusion Technique

Carbon nanotube （CNT）-reinforced 6061Al alloy matrix composites were prepared by chemical vapor depo- sition （CVD） combined with hot extrusion technique. During the preparation process, the 6061Al flakes obtained by ball milling of the 6061Al spherical powders were subjected to surface modification to introduce a hydrophilic polyvinyl alcohol （PVA） membrane on their surface （6061Al@PVA） to bond strongly with nickel acetate [Ni（II）]. Then the 6061Al@PVA flakes bonded with Ni（II） were calcined and reduced to Ni nanoparticles, which were then heat-treated at 580 ℃ to remove PVA for obtaining even Ni/6061Al catalyst. After that, the as-obtained Ni/6061Al catalyst was employed to synthesize CNTs on the surface of the 6061Al flakes by CVD. After hot extrusion of the CNT/6061Al composite powders, the as-obtained CNT/6061Al bulk composites with 2.26 wt% CNTs exhibited 135% increase in yield strength and 84.5% increase in tensile strength compared to pristine 6061Al matrix.