Alternating current (AC) electrokinetics is a facile way of patterning colloidal particles into advanced structures. We demonstrate the combined use of AC dielectrophoresis (AC-DEP) and AC electrohydrodynamics (AC-EHD) in a microwell electrode geometry for size-tunable assembly of gold nanoparticles (AuNPs) into one-dimensional microwires and two-dimensional films. The AC-DEP force scales with both particle size and field frequency, whereas the AC-EHD force depends only on the field frequency. So, a critical particle diameter (d c ) exists, below which the EHD phenomenon becomes more important and beyond which the DEP force is dominating. We performed theoretical and experimental studies to determine "d c " and how it gets affected by operating parameters like field frequency, voltage, particle number, electrolyte concentration, electrode size, and geometry. Our results show that the morphologies of the colloidal structures transition from films to microwires as the NP diameters vary from nanometers (d c ), and no assembly takes place at intermediate sizes (∼d c ). While the film formation is governed purely by surface EHD flows, microwire synthesis is a result of EHD-assisted DEP phenomenon. Also, a minimum particle number, a low salt concentration, and an optimum frequency range is required to initiate assembly.

No abstract

Applications of nano-scaled energetic materials in diesel and diesel-biodiesel blends as catalytic agents have emerged contemporarily in pace to develop an efficient and eco-friendly alternative fuel for compression ignition (CI) engines. Inclusion of nanoparticles as additives for CI engine fuels promises as overall improver of engine performance and emission characteristics. However, simultaneous control on engine performance parameters and emission characteristics is usually difficult. Dispersion of nano-additives improves combustion efficiency by altering specific fuel properties of diesel. Average particle size of 40-50 nm facilitate greater surface-to-volume ratio, hence ensure more complete combustion through further chain reactions during combustion. Nanoparticles as catalytic agents in diesel and its proportionate blends have recently emerged as game changer but their potential is in-fact not fully explored for market acceptability. The following are the major challenges that are to be considered in future researches: (a) There is a need of onroad testing in real ambient conditions, (b) Effects of exhaust emission fuelled with nanocatalysts on human breathing, (c) Overall effects on diesel engines of agricultural tractors and other heavy earth moving machines which are designed for high load factors, and (d) Effects of such modified fuels on driving habits of consumers.

No abstract

No abstract