Reverse movement and coalescence of water microdroplets in electrohydrodynamic atomization.

When a high voltage is applied to a liquid pumped through a needle, charged microdroplets can be formed, which are carried along the electric field lines. This phenomenon is called electrohydrodynamic atomization (EHDA), or simply electrospray. In this work we show that in the case of water, droplets may reverse their paths flying back toward the liquid meniscus, sometimes making contact with it. Such reverse movement is caused by polarization of the water inside the strong electric field. To understand this phenomenon we developed a way to calculate the droplet charge using its trajectory obtained by high-speed imaging. The values found showed that these droplets are charged between 2.5% and 19% of their Rayleigh limit.

Significant DQw1 association in achalasia.

Achalasia is a neuromuscular disorder of the esophagus with unknown etiology. There have been suggestions that this disorder is immunologically mediated. To examine this possibility, HLA phenotyping was prospectively performed on 40 patients with documented achalasia (24 Caucasian, 16 blacks). Results showed a positive association for the class II HLA antigen, DQw1, with 83% of Caucasians (P less than 0.02) and 86% of blacks having the antigen (NS). The relative risk for developing achalasia with the presence of DQw1 was 4.2 in Caucasians and 3.6 in blacks. A negative correlation for the DRw53 antigen was noted in Caucasian patients with a relative risk of 0.23. These results indicate an immunogenetic association for achalasia and provide insight into the pathogenesis of this disorder.