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LiCoO 2 is an important lithium storage compound that adopts a distorted rock-salt structure of the α -NaFeO 2 type. After the discovery of reversible lithium (de)intercalation in this layered host compound by Mizushima et al., [ 1 ] this material became central to the introduction and subsequent development of lithium-ion batteries (LIBs) of high energy and power density. The advantages of LiCoO 2 as a lithium-ion positive electrode material are numerous and include high specifi c capacity and energy density, [ 1 ] high electronic [ 2 ] and ionic [3][4][5] conductivities, long cycle life, [ 6 ] and relatively modest structural distortion with varying lithium concentration. [ 7 ] A broad range of isostructural compositions within the pseudoquaternary system Li(Co,Ni,Mn,Al)O 2 remain at the forefront of lithium battery research and development. [ 8 ] Despite the relatively modest structural distortion induced by electrochemical cycling ( ≈ 1.9 vol%), [ 7 ] LiCoO 2 -type active particles experience heavy mechanical damage after a modest number of electrochemical cycles. Fractured particles and large dislocation densities have been observed in transmission electron microscopy (TEM) studies of LiCoO 2 , [9][10][11] LiAl 0.25 Co 0.75 O 2 , [ 11 ] and LiNi 1/3 Mn 1/3 Co 1/3 O 2 . [ 12 ] We have previously described this phenomenon of electrochemical cyclinginduced fracture as electrochemical shock, due to the close analogy with thermal shock of brittle materials. [ 13 ] Electrochemical shock has been demonstrated to correlate with impedance growth and capacity fade in lithium-ion batteries. [ 14 ] Following initial work by Huggins and Nix, [ 15 ] there have been many recent analytical and numerical studies aimed at identifying operating conditions, materials, and/or microstructures that prevent or limit electrochemical shock. [ 13 , 16-23 ] Experimentally measured elastic and fracture properties are essential to enable the use of these models as battery engineering tools. LiCoO 2 is a model system to study the mechanical behavior of lithium-storage compounds, and is widely used in both materials research and industrial LIB applications. However, the mechanical properties of LiCoO 2 are still not well established. For example, there exists a wide range of Young's elastic moduli E reported from both experiments and simulations. Wang et al. [ 24 ] reported the bulk elastic modulus B of LiCoO 2

Poly(lactic acid) (PLA), a biobased, degradable polymer has been used recently in the field of oil and gas. These applications require rapid hydrolytic degradation of PLA especially at low temperatures. This work reports a simple and ready-to-scale up chemistry of using zinc oxide nanoparticles (ZnO NPs) to catalyze the hydrolytic degradation of PLA at the temperatures well below its glass transition temperature. Furthermore, for the first time, we have applied the nondestructive analytical method of 1 H T 2 NMR relaxometry to measure the apparent rate constants of PLA hydrolysis in solid, heterogeneous/composite systems that have multiple and complex reaction kinetics. We demonstrate that the activation energy for ZnO catalyzed PLA hydrolysis is about 38% lower than that of pure PLA hydrolysis.

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For both materials engineering research and applied biomedicine, a growing need exists to quantify mechanical behaviour of tissues under defined hydration and loading conditions. In particular, characterisation under dynamic contact-loading conditions can enable quantitative predictions of deformation due to high rate 'impact' events typical of industrial accidents and ballistic insults. The impact indentation responses were examined of both hydrated tissues and candidate tissue surrogate materials. The goals of this work were to determine the mechanical response of fully hydrated soft tissues under defined dynamic loading conditions, and to identify design principles by which synthetic, air-stable polymers could mimic those responses. Soft tissues from two organs (liver and heart), a commercially available tissue surrogate gel (Perma-Gel TM ) and three styrenic block copolymer gels were investigated. Impact indentation enabled quantification of resistance to penetration and energy dissipative constants under the rates and energy densities of interest for tissue surrogate applications. These analyses indicated that the energy dissipation capacity under dynamic impact increased with increasing diblock concentration in the styrenic gels. Under the impact rates employed (2 mm/s to 20 mm/s, corresponding to approximate strain energy densities from 0.4 kJ/m 3 to 20 kJ/m 3 ), the energy dissipation capacities of fully hydrated soft tissues were ultimately well matched by a 50/50 triblock/diblock composition that is stable in ambient environments. More generally, the methodologies detailed here facilitate further optimisation of impact energy dissipation capacity of polymer-based tissue surrogate materials, either in air or in fluids.

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Highly nanoporous surfaces were observed on the underside of Ni splats. Experiments varying process parameters and substrate treatments were performed to determine the mechanism of pore formation. A theory of impact-induced bubble nucleation and freezing into pores is presented, and calculations are compared with experimental results. Pore formation and morphology is strongly dependent on substrate (a) thermal properties as they affect time for bubble growth before solidification into pores and (b) roughness as submicron scratches enhance nucleation by providing heterogeneous sites and several micron grooves reduce the driving force for nucleation. Splat pull-off experiments are shown that suggest bubble nucleation and pore formation strongly affect adhesion, and represent a strong contribution to the effectiveness of surface roughening. Finally, this observation shows the potential for the manufacturing of high-surface area materials using thermal spray.