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Abstract Recently, powder metallurgy inspired low-temperature (below the melting temperature) sintering has been proposed as an innovative technology for the processing of eco-friendly stereocomplex-type polylactide (SC-PLA) from its nascent powder, without triggering noticeable thermal degradation. The physicochemical performances of the obtained SC-PLA products are governed by the newly formed SC crystallites with a remarkable ability to weld the interfaces between adjacent powder particles, however, the insufficient interdiffusion of poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA) chains across the interfaces makes it challenging to form sufficient amounts of new SC crystallites. In the present work, we describe a facile and robust strategy to address this challenge by coating a trace amount (e.g., 0.001 wt%) of disentangled carbon nanotubes (CNTs) on the SC-PLA particle surfaces. During the subsequent sintering, these interface-localized CNTs can function as efficient nucleating agent to substantially promote the SC crystallization of PLLA/PDLA chains on their surfaces and finally countless SC crystallites are formed to strongly weld the interfaces as welded joints. Accordingly, SC-PLA/CNTs products possessing superb heat/solvent resistances and mechanical strength have been fabricated. Impressively, with the introduction of 0.001 wt% CNTs, the tensile strength is significantly enhanced from 45.8 MPa to 67.2 MPa. Most importantly, there is a linear relationship between the tensile strength and the content of the CNTs induced SC crystallites. Overall, this wok could provide a practical guidance for the design and fabrication of high-performance SC-PLA products through low-temperature sintering assisted by nanofillers like CNTs. Graphical abstract Image 1 Highlights • SC-PLA products with superb performances has been fabricated by CNTs assisted low-temperature sintering. • The disentangled CNTs were coated on the surface of SC-PLA powder particles before sintering. • These CNTs can substantially promote SC crystallization across particle interfaces as nucleating agent. • Countless new SC crystallites are induced to strongly weld the interfaces and thus enhance the product performances. • The linear relationship between tensile strength and CNTs induced SC crystallites has been established. [ABSTRACT FROM AUTHOR]

Five new caged polyprenylated xanthones ( 1a , 2a , 3 , 10a and 10b ), and 12 known related compounds were isolated from the resin of Garcinia hanburyi . Their structures were elucidated by detailed spectroscopic analyses and their α-glucosidase inhibitory activities were investigated in vitro. Most of xanthones showed modest inhibitory activity against α-glucosidase. [ABSTRACT FROM AUTHOR]

Abstract: The effect of the Zr addition on the glass-forming ability (GFA) and crystallization kinetics of Y56Al24Co20 alloy has been investigated. It is found that Y46Zr10Al24Co20 has a reduced glass transition temperature as large as 0.626 at a heating rate of 20K/min. Crystallization kinetic studies show that the activation energies derived from Kissinger equation for Y46Zr10Al24Co20 metallic glass of E g =415.64kJ/mol, E x =279.74kJ/mol and E p =319.51kJ/mol for glass transition, onset crystallization and crystallization peak, respectively, which are higher than those values for Y56Al24Co20 one. The dependence of the glass transition on the heating rate was analyzed in terms of the Vogel–Fulcher–Tamman (VFT) equation. The glass-forming ability of the alloy was discussed based on the composition-dependent melting behavior, the reduced glass transition temperature, and the fragility parameter. It is shown that substitution of 10at.% Zr for Y improves the glass-forming ability and the thermal stability of Y56Al24Co20 alloy. [Copyright &y& Elsevier]

Four nickel-based oxide dispersion strengthened (ODS) superalloys with the additions of YH 2 , Y 2 O 3 , La 2 O 3 and CeO 2 (denoted as ODS-Y1 ODS-Y2, ODS-La and ODS-Ce) are prepared, respectively. The tensile tests at temperatures ranging from room temperature (RT) to 1000 °C were conducted on them. In this work, by means of microstructure characterization and theoretical modeling, different strengthening mechanisms including grain boundary strengthening, solution strengthening, dislocations and dispersion strengthening, were estimated to contribute to the yield strength in different degrees, which would help to further enhance the tensile properties of alloys through nanoparticles optimization thereafter, and the formation and evolution mechanism of nanoparticles are discussed. The results show that ODS-Y1 has the smallest particles and the best comprehensive mechanical property in the tested alloys. The nanoparticles having M-Al-rich (M = Y, La, Ce) cores and Ti-O-rich shells structure are observed in nickel-based ODS superalloys, and the M-Al-O are preferentially formed, due to the higher diffusion rate of Al atom and high M/Al value. Then Ti and O atoms diffuse to the surface of nanoparticles, forming a core-shell structures in the later precipitation stages. • The nickel-based ODS superalloys with the additions of YH 2 , Y 2 O 3 , La 2 O 3 and CeO 2 were fabricated by MA and HIP, respectively. The crystallographic information of oxide particles in different specimens were characterized by the XRD, HRTEM and FFT images. • The theoretical modeling, different strengthening mechanisms including grain boundary strengthening, solution strengthening, dislocations and dispersion strengthening, were estimated to contribute to the yield strength. • The nanoparticles having M-Al-rich (M = Y, La, Ce) cores and Ti-O-rich shells structure were observed in nickel-based ODS superalloys, and the M-Al-O are preferentially formed, due to the higher diffusion rate of Al atom and high M/Al value. Then Ti and O atoms diffuse to the surface of nanoparticles, forming a core-shell structures in the later precipitation stages. [ABSTRACT FROM AUTHOR]