Using the method of homogenization, we present a systematic derivation of the macroscopic equations for air ̄ow and chemical vapor transport in an unsaturated zone with a periodic structure of heterogeneity. The e€ective speci®c discharge and hydrodynamic dispersion coecient are expressible in terms of some cell functions, whose analytical solutions are sought for the simple case of alternate s...

Assuming high temperature and taking subleading temperature dependence into account, gauge dependence of one-loop electron dispersion relation is investigated in massless QED at zero chemical potential. The analysis is carried out using a general covariant gauge. It is proved that the high-momentum limit of the dispersion relation is gauge independent. It is also shown that the effective mass i...

The release of a chemical/biological/nuclear (C/B/N) agent in a city remains a viable threat. As these silent, invisible and odorless plumes can cause massive casualties that would overwhelm emergency facilities, modeling, tracking and real-time prediction of plume dispersion and lethality is central to developing a user-friendly first responder's tool for evacuating civilians and managing emer...

Waterborne polyaniline (PANI) dispersion has got extensive attention due to its environmental friendliness and good processability, whereas the storage stability and mechanical property have been the challenge for the waterborne PANI composites. Here we prepare for waterborne PANI dispersion through the chemical graft polymerisation of PANI into epichlorohydrin modified poly (vinyl alcohol) (EP...

Multiwalled carbon nanotubes (MWCNTs) are considered to be ideal multifunctional materials for biorelated applications, but there is still some controversy regarding their toxicity. In addition, the poor dispersibility of MWCNTs in either water or organic solvents has limited their practical applications. Therefore, obtaining a good dispersion is one of the key issues in their applications. In ...

Ever since its initial development, solution NMR spectroscopy has been used as a tool to study conformational exchange. Although many systems are amenable to relaxation dispersion approaches, cases involving highly skewed populations in slow chemical exchange have, in general, remained recalcitrant to study. Here an experiment to detect and characterize "invisible" excited protein states in slo...

A tandem ion mobility instrument based on differential mobility spectrometry (DMS) was used to demonstrate selectivity in response through differences in field dependence of mobility for ions in purified air at ambient pressure. The concept of chemical selectivity solely from characteristic dispersion curves or from field dependence of ion mobility was experimentally demonstrated in three steps...

Fluctuation scaling reports on all processes producing a data set. Some fluctuation scaling relationships, such as the Horwitz curve, follow exponential dispersion models which have useful properties. The mean-variance method applied to Poisson distributed data is a special case of these properties allowing the gain of a system to be measured. Here, a general method is described for investigati...

The discovery of carbon nanotubes offers exciting opportunities for the development of novel high property materials. Disaggregation and uniform dispersion are critical challenges that must be met to successfully produce such high property materials, since carbon nanotubes tend to self-associate into micro-scale aggregates. This results in products with inferior mechanical and electric performa...