Direct measurement of the viscoelectric effect in water

The viscoelectric effect concerns the increase in viscosity of a polar liquid in an electric field due to its interaction with the dipolar molecules and was first determined for polar organic liquids more than 80 y ago. For the case of water, however, the most common polar liquid, direct measurement of the viscoelectric effect is challenging and has not to date been carried out, despite its importance in a wide range of electrokinetic and flow effects. In consequence, estimates of its magnitude for water vary by more than three orders of magnitude. Here, we measure the viscoelectric effect in water directly using a surface force balance by measuring the dynamic approach of two molecularly smooth surfaces with a controlled, uniform electric field between them across highly purified water. As the water is squeezed out of the gap between the approaching surfaces, viscous damping dominates the approach dynamics; this is modulated by the viscoelectric effect under the uniform transverse electric field across the water, enabling its magnitude to be directly determined as a function of the field. We measured a value for this magnitude, which differs by one and by two orders of magnitude, respectively, from its highest and lowest previously estimated values.

Dynamics in direct two-photon transition by frequency combs

Based on the proposed theoretical model of a three-level system, the optical Bloch equations including the direct two-photon transition (DTPT) process using the optical frequency comb (OFC) were derived and the population distribution of particles in the upper states varying with the velocity of the atoms was obtained. Comparing to the resonance two-photon transition process, that population was increased by a factor of 1.4 without the Doppler shift, which is consistent with our previous experimental results. Simultaneously, the relationship between momentum transfers, and atomic velocity and pulse number were analyzed. When applied to a multi-level system it was found the population of particles in the excited states increased by a few percentages. The novel approach of DTPT using OFC improved the utilization of comb teeth and atoms, increased the momentum transfer path, reduced the reachable Doppler temperature limit, and encouraged us to use OFC to cool multiple elements simultaneously through the DTPT process. By analyzing the Doppler temperature of 133Cs and 87Rb in one dimension, it was found that this process can lower a temperature below 100 mK and generate dipolar molecules 133Cs87Rb via photoassociation, which provides us a new tool to create dipolar molecules and to investigate their complex rovibrational spectra in ultra-cold chemistry.

Theoretical modeling and experimental study of sodium oleate properties for wastewater cleaning with magnetic nanoparticles stabilized with oleate

We present some preliminary results regarding possible reducing of environment phenol contamination with nanotechnology involving. Magnetic nanoparticles stabilized in water dispersion with oleate were prepared for experimental testing of their interaction with wastewater samples containing phenol residues from industrial and sanitation sources. Magnetite with moderate level of cobalt doping was synthesized by co-precipitation method in the form of nanoparticles; further their surface was modified by the reaction with sodium oleate solution. Quantum chemical simulation of oleate structure recommended it for the interaction with water dipolar molecules as well as with metal cations at the nanocores surface. Transmission Electron Microscopy confirmed fine granulation of the prepared sample meaning significant total surface of nanoparticle sample. Phenol loaded water model was let to interact with magnetic nanoparticles in various reaction conditions. Phenol absorbance in the main spectral band showed the concentration diminution following magnetic nanoparticle action in the presence of ultraviolet radiation and hydrogen peroxide supply. Further experiments are planned for the better optimization of the phenol concentration decreasing in the large volumes of wastewater with adequate nanostructures, able to develop efficient interaction mechanisms with pollutant molecules.

Single-component organic molecular ferroelectrics based on disk- or wheel-like rotation

Large polarizations and their reversible switching, which are indispensable for many functional ferroelectric applications, are achieved in new single-component organic molecular ferroelectrics with rotating strongly dipolar molecules or substituents. In...