All of the AB_{2} Laves phases discovered so far satisfy the general crystalline structure characteristic of translational symmetry; however, we report here a new structured Laves phase directly precipitated in an aged Mg-In-Ca alloy by using aberration-corrected scanning transmission electron microscopy. The nanoprecipitate is determined to be a (Mg,In)_{2}Ca phase, which has a C14 Laves structure (hcp, space group: P6_{3}/mmc, a=6.25  Å, c=10.31  Å) but without any translational symmetry on the (0001)_{p} basal plane. The (Mg,In)_{2}Ca Laves phase contains two separate unit cells promoting the formation of five tiling patterns. The bonding of these patterns leads to the generation of the present Laves phase, followed by the Penrose geometrical rule. The orientation relationship between the Laves precipitate and Mg matrix is (0001)_{p}//(0001)_{α} and [11[over ¯]00]_{p}//[112[over ¯]0]_{α}. More specifically, in contrast to the traditional view that the third element would orderly replace other atoms in a manner of layer by layer on the close-packed (0001)_{L} plane, the In atoms here have orderly occupied certain position of Mg atomic columns along the [0001]_{L} zone axis. The finding would be interesting and important for understanding the formation mechanism of Laves phases, and even atom stacking behavior in condensed matter.

Considering the tremendous value of citation metadata, many methods have been proposed to automate Citation Metadata Extraction (CME). The existing methods primarily rely on the content analysis of citation text. However, the results from such content-based methods are often unreliable. Moreover, the extracted citation metadata is only a small part of the relevant metadata that spreads across the Internet. As opposed to the content-based CME methods, this paper proposes a Web-based CME approach and a citation enriching system, called as BibAll, which is capable of correcting the parsing results of content-based CME methods and augmenting citation metadata by leveraging relevant bibliographic data from digital repositories and cited-by publications on the Web. BibAll consists of four main components: citation parsing, Web-based bibliographic data retrieval, irrelevant bibliographic data filtering, and relevant bibliographic data integration. The system has been tested on the publicly available FLUX-CIM dataset. Experimental results show that BibAll significantly improves the citation parsing accuracy and augments the metadata of the original citation.

We report the ab initio prediction of a negative Barkas coefficient in lithium fluoride (LiF) insulator at low velocity (v < 0.25 a:u:, E kin ∼ 2 keV). The electronic stopping power of protons in LiF has been extensively studied both experimentally and theoretically because of a controversial threshold effect. While our time-dependent density-functional theory simulations confirm the presence of a velocity threshold below which the proton stopping power vanishes, our calculations demonstrate that the antiprotons do not experience such a threshold. The combination of those two contrasting behaviors gives rise to an unprecedented negative Barkas effect: the stopping power of antiprotons is larger than that of protons. We identify that the slow antiproton at close encounter destabilizes a p orbital of the F − anion pointing toward the antiproton. This particular orbital becomes highly polarizable and hence contributes much to the stopping power.

The γ″ nanosaucer precipitates in many Mg-RE-Zn(Ag) alloys, also named the G. P. zones in some cases such as in the Mg−Ca−Al(Zn) alloys, play the critical role in strengthening the α-Mg matrix and enhancing their creep resistance. However, the previous reports on the crystal structure of γ″ phase are still controversial at present, and thus it is hard to correlate the γ″ phase with the mechanical properties of Mg alloys. In this study, we confirmed a new topological close-packed (TCP) structure for the γ″ precipitate in a typical peak-aged Mg−Gd−Zn alloy using Cscorrected high-angle annular dark-field-scanning transmission electron microscopy (HAADF-STEM) and computational simulation. The new structure is totally different from the commonly accepted structure for the γ″ phase that consisted of three atomic layers. In contrast, this TCP nanosaucer precipitate is composed of the monolayer atomic icosahedral clusters with five (0001) γ″ atomic layers (hexagon structure, space group: P6/mmm, a = 5.56 Å, c = 5.21 Å; stacking sequence: ABCBA; grid structure: A → 6 3 (Mg), B → 3 6 (Gd), C → 3636(Zn)). Moreover, the chemical formula of the γ″ nanosaucer precipitate is also identified as Mg 2 Gd 2 Zn 3 (A 2 B 2 C 3 ), consistent with previous 3D atom probe results. The orientation relationship between the γ″ precipitate and α-Mg matrix is also determined as (0001) γ″ // (0001) α ; [011̅ 0] γ″ // [112̅ 0] α . The finding would not only shed light on deeper understanding of the confined existence of monolayer icosahedral in the field of crystallography, and of the γ″ nanosaucer precipitates strengthening mechanism in Mg alloys, but also guides the further design of new high-strength and creep resistant Mg alloys.