Herein, we report on the ability to create complex 2-D and 3-D silica networks in vitro via polycationic peptide-mediated biosilicification under experimentally altered chemical and physical influences. These structures differ from the sphere-like silica network of particles obtained in vitro under static conditions. Under chemical influences, overall morphologies were observed to shift from a characteristic network of sphere-like silica particles to a sheetlike structure in the presence of -OH groups from additives and to sharp-edged, platelike structures in the presence of larger polycationic peptide matrixes. Under physical influences, using externally applied force fields, overall silica morphologies were observed to transition from sphere-like to fiberlike and dendrite-like structures. These findings could lead to the future development of bio-inspired complex 2-D and 3-D silica micro- and nano-devices.

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Latent energy storage capacity was analyzed for a system consisting of carbon nanoparticles doped phase change materials ͑PCMs͒. Three types of samples were prepared by doping shell wax with single wall carbon nanotubes ͑SWCNTs͒, multiwall CNTs, and carbon nanofibers. Differential scanning calorimetry was used to measure the latent heat of fusion. The measured values of latent heat for all the samples showed a good enhancement over the latent heat of pure wax. A maximum enhancement of approximately 13% was observed for the wax/SWCNT composite corresponding to 1% loading of SWCNT. The change in latent heat was modeled by using an approximation for the intermolecular attraction based on the Lennard-Jones potential. A theoretical model was formulated to estimate the overall latent energy of the samples with the variation in volume fraction of the nanoparticles. The predicted values of latent energy from the model showed good agreement with the experimental results. It was concluded that the higher molecular density of the SWCNT and its large surface area were the reasons behind the greater intermolecular attraction in the wax/SWCNT composite, which resulted in its enhanced latent energy. The novel approach used to predict the latent heat of fusion of the wax/nanoparticle composites has a particular significance for investigating the latent heat of PCM with different types of nanoparticle additives.