A cupronickel-based micromesh film for use as a high-performance and low-voltage transparent heater

Uniformly interconnected CuNi mesh film was prepared by using a simple transfer printing method. The CuNi mesh films showed excellent heating performances, which reached a maximum steady-state temperature of 225 °C in 60 s, with respect to applied low-voltage (9 V), and better thermal stability than that of the pure Cu mesh film.

Supersaturation in the Wyoming CCN Instrument

Two thermal diffusion cloud condensation nuclei (CCN) instruments were intercompared using a nearly monodisperse test aerosol composed of sodium chloride and ammonium sulfate. The main objective of this work is the determination of the maximum steady-state supersaturation within a thermal diffusion chamber. This required analysis of the uncertainties associated with the calibration of the instrument’s plate temperature and light scattering measurement systems. The fraction of test particles activating to form cloud droplets, the activated fraction, was evaluated over a range of dry particle diameters at four supersaturations. Values of both the particle size, corresponding to an activated fraction equal to 0.5, and the width of a fitted activation function were derived. The former was used to evaluate the maximum steady-state chamber supersaturation. These studies reveal three significant findings. First, the derived chamber supersaturation is ∼40% smaller than values based on temperature measured at the top and bottom of the diffusion chamber. Second, using deliquesced test particles, mobility selected at a prescribed relative humidity, it is shown that the 40% discrepancy is not the result of a test particle shape effect. Third, the width of the activation function is substantially larger than the width of the test particle size spectra. Plausible explanations for the 40% bias are considered. Contributors are the unintentional overestimation of the temperature difference imposed across the CCN chamber and the implicit assumption that water at the top and bottom of the CCN chamber has a vapor pressure equal to that over pure water.

Polymerization of FtsZ, a Bacterial Homolog of Tubulin

FtsZ is a bacterial homolog of tubulin that is essential for prokaryotic cytokinesis.In vitro, GTP induces FtsZ to assemble into straight, 5-nm-wide polymers. Here we show that the polymerization of these FtsZ filaments most closely resembles noncooperative (or “isodesmic”) assembly; the polymers are single-stranded and assemble with no evidence of a nucleation phase and without a critical concentration. We have developed a model for the isodesmic polymerization that includes GTP hydrolysis in the scheme. The model can account for the lengths of the FtsZ polymers and their maximum steady state nucleotide hydrolysis rates. It predicts that unlike microtubules, FtsZ protofilaments consist of GTP-bound FtsZ subunits that hydrolyze their nucleotide only slowly and are connected by high affinity longitudinal bonds with a nanomolarKD.