ABSTRACT
Nanoindentation and electron microscopy have been used to examine the length-scale-dependent stress relaxation mechanisms in well-annealed, high-purity indium at a homologous temperature of 0.69. The experimental methods, analysis, and observations serve as a stepping stone in identifying the stress relaxation mechanisms enabling the formation and growth of metallic dendrites originating at the buried interface between a metallic anode and a solid electrolyte separator. Indium's load-displacement data are found to be very similar to that of high-purity lithium. Residual hardness impressions show two distinct surface morphologies. Based on these morphologies, the measured hardness, and the estimated pile-up volume, it is proposed that residual impressions exhibiting significant pile-up are the result of deformation dominated by interface diffusion. Alternatively, impressions with no significant pile-up are taken to be the result of shear-driven dislocation glide. An analytical model is presented to rationalize the pile-up profile using interface diffusion.
ABSTRACT
Sn based anodes allow for high initial capacities, which however cannot be retained due to the severe mechanical damage that occurs during Li-insertion and de-insertion. To better understand the fracture process during electrochemical cycling three different nanopowders comprised of Sn particles attached on artificial graphite, natural graphite or micro-carbon microbeads were examined. Although an initial capacity of 700 mAh g(-1) was obtained for all Sn-C nanopowders, a significant capacity fade took place with continuous electrochemical cycling. The microstructural changes in the electrodes corresponding to the changes in electrochemical behavior were studied by transmission and scanning electron microscopy. The fragmentation of Sn observed by microscopy correlates with the capacity fade, but this fragmentation and capacity fade can be controlled by controlling the initial microstructure. It was found that there is a dependence of the capacity fade on the Sn particle volume and surface area fraction of Sn on carbon.
ABSTRACT
beta-cyclodextrin immobilized on Pd nanoparticles was successfully employed as an efficient phase-transfer catalyst in aqueous biphasic hydrogenation reactions.
ABSTRACT
Biologists, and diatomists in particular, have long studied the properties of single-cell algae, and engineers are just discovering how to exploit features unique to these organisms. Their uniform nanopore structure, microchannels, chemical inertness, and silica microcrystal structure suggest many nanoscale applications. This paper proposes three potential research initiatives taking advantage of diatom morphology and mechanical and chemical properties: (1) embedding diatom frustules in a metal-film membrane; (2) magnetizing frustules for pinpoint drug delivery; and (3) producing silica nanopowders from frustules. The potential benefits of each initiative and its technical challenges are outlined.
Subject(s)
Biomedical Engineering/methods , Biomedical Technology/methods , Diatoms/physiology , Diatoms/ultrastructure , Drug Delivery Systems/methods , Nanostructures/chemistry , Nanotechnology/methods , Biomedical Engineering/instrumentation , Biomedical Technology/instrumentation , Biomimetics/instrumentation , Biomimetics/methods , Diatoms/chemistry , Nanostructures/ultrastructure , Nanotechnology/instrumentation , Powders , Silicon Dioxide/chemistryABSTRACT
Functional, conjugated molecular structures have been fabricated on Au nanoparticles via the Sonogashira coupling reactions.
ABSTRACT
The fluorescence of beta-cyclodextrin-modified CdS quantum dots can be reversibly tuned by introducing different substrates in aqueous media.