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We report on a study of morphology evolution following de-lithiation of Li-Pb alloys, produced by the electrochemical lithiation of Pb particulate and sheet electrodes. Electrochemical titration and time of flight measurements were performed in order to determine the intrinsic diffusivity of Li, DLi , as a function of alloy composition, which ranged from 10 −12 -10 −10 cm 2 s −1 . Morphology evolution was studied under conditions of galvanostatic and potentiostatic dealloying. For the particulate electrodes, we observed dealloyed morphologies corresponding to Kirkendall voids, negative dendrites, void nodules and conventional bicontinuous nanoporous structures. In the case of Pb sheets, similar dealloyed morphologies were obtained under galvanostatic dealloying conditions, however, in the case of potentiostatic dealloying, we did not observe the formation of large volume bicontinuous nanoporous structures. For Pb sheets lithiated to a composition corresponding to the Li 8 Pb 3 phase and galvanostatically dealloyed at current densities ∼1 mAcm −2 , voltage oscillations were observed with periods of 70-90 s and amplitudes ranging from 20-130 mV. Current oscillations were also observed for potentiostatic dealloying at 1 V vs Li + /Li. The possible mechanism of these oscillations is discussed and attributed to a salt film precipitation and lift-off process.

Finding non-standard or new metabolic pathways has important applications in metabolic engineering, synthetic biology and the analysis and reconstruction of metabolic networks. Branched metabolic pathways dominate in metabolic networks and depict a more comprehensive picture of metabolism compared to linear pathways. Although progress has been developed to find branched metabolic pathways, few efforts have been made in identifying branched metabolic pathways via atom group tracking. In this paper, we present a pathfinding method called BPFinder for finding branched metabolic pathways by atom group tracking, which aims to guide the synthetic design of metabolic pathways. BPFinder enumerates linear metabolic pathways by tracking the movements of atom groups in metabolic network and merges the linear atom group conserving pathways into branched pathways. Two merging rules based on the structure of conserved atom groups are proposed to accurately merge the branched compounds of linear pathways to identify branched pathways. Furthermore, the integrated information of compound similarity, thermodynamic feasibility and conserved atom groups is also used to rank the pathfinding results for feasible branched pathways. Experimental results show that BPFinder is more capable of recovering known branched metabolic pathways as compared to other existing methods, and is able to return biologically relevant branched pathways and discover alternative branched pathways of biochemical interest. The online server of BPFinder is available at http://114.215.129.245:8080/atomic/. The program, source code and data can be downloaded from https://github.com/hyr0771/BPFinder.

While it is well known that 12-13 at.% chromium is required for stainless-like passivation behavior of binary Fe-Cr alloys, there remain outstanding questions regarding the compositional dependence of this behavior. In order to explore these issues, we examined the passivation behavior of short-range ordered (SRO) Fe-Cr alloys and compared this to that of their random solid solution counterpart. Our results reveal that for alloys containing between 12-18 at.% Cr, passivation in the SRO alloys is delayed and we attribute this to ordering effects on percolation behavior. Finally, we discuss some major outstanding questions regarding passivation in the Fe-Cr system and suggest that first-principles based calculations could make important contributions to our understanding of passivation in this system.