in liposomes and can be liberated by heating the system for a short period. Crucially, the heating time determines the amount of enzyme liberated; with that, the release rate can be tuned by the time of heating.
Non-scissile mechanophores Force-induced transformations of polymer-bound functionalities have the potential to produce a rich array of stress-responsive behaviour. One area of particular interest is the activation of non- scissile mechanophores in which latent reactivity can be unveiled that, under the appropriate conditions, could lead to constructive bond formation in materials exposed to typically destructive stress. The mechanical activation of a bicyclo[3.2.0]heptane (BCH) mechanophore has been demonstrated via selective labelling of bis-enone products (Z. S. Kean, A. L. Black Ramirez, Y. Yan, S. L. Craig; J. Am. Chem. Soc., 2012, 134, 12939) (Scheme 3). BCH ring-opening produces large local elongation (>4 Å) and products that are reactive to conjugate additions under mild conditions. Subsequent photocyclisation regenerates the initial BCH functionality, providing switchable structure and reactivity along the polymer backbone in response to stress and visible light.
Plugless charging Energy generation and energy storage are two distinct processes that are usually accomplished using two separated units designed on the basis of different physical principles, such as piezoelectric nanogenerator and Li-ion battery; the former converts mechanical energy into electricity, and the latter stores electric energy as chemical energy. Scientists have directly hybridised the two processes into one, in which the mechanical energy is directly converted and simultaneously stored as chemical energy without going through the intermediate step of first converting into electricity (X. Xue, S. Wang, W. Guo, Y. Zhang, Z. L. Wang; Nano Letters, doi: 10.1021/nl302879t) (Scheme 4). By replacing the polyethylene (PE)
separator as for conventional Li battery with a piezoelectric poly(vinylidene fluoride) (PVDF) film, the piezoelectric potential from the PVDF film as created by mechanical straining acts as a charge pump to drive Li ions to migrate from the
anode accompanying charging reactions at electrodes. The researchers have fabricated a power pack based on this technology in which a coin-type battery can be recharged simply by repeatedly pressing it. This development could allow the charging mobile phone and other personal electronic device batteries, for example, by slotting them into the sole of your shoe and walking on it.
membrane, to the TiO2 nanotube array conventional LiCoO2 Photoreduction of CO2 induction period) and a lesser amount
Hg lamp in the presence of H2 or H2 leads to the formation of CH4
methane by water Photolysis of CO2
52 Chemistry&Industry • November 2012 to at 185nm using a O (after an cathode, across the Scheme 6