The influence of ions and humidity on charging of solid hydrophobic surfaces in slide electrification.

Water drops sliding down inclined hydrophobic, insulating surfaces spontaneously deposit electric charges. However, it is not yet clear how the charges are deposited. The influence of added non-hydrolysable salt, acid, or base in the sliding water drops as well as the surrounding humidity on surface electrification and charge formation is also not yet fully understood.

H NMR Study of Polymer Segmental Dynamics at Varying Cross-Linking in Poly(-isopropylacrylamide) Microgels.

A microscopic understanding of the internal structure and dynamics of poly(-isopropylacrylamide) (PNIPAM) chains, in microgel colloids, is developed using deuterium NMR (H NMR) to study deuterated PNIPAM suspensions as functions of temperature and pressure for four cross-linker molar fractions (). The PNIPAM polymers were labeled with deuterons at the backbone (-PNIPAM) or on side chains (-PNIPAM). H NMR spectra of the -PNIPAM suspensions for all cross-linker molar fractions indicated freely moving chains at low temperature and a nearly immobilized fraction above ∼35 °C.

Georeferencing of Personal Exposure to Radiofrequency Electromagnetic Fields from Wi-Fi in a University Area.

In the last two decades, due to the development of the information society, the massive increase in the use of information technologies, including the connection and communication of multiple electronic devices, highlighting Wi-Fi networks, as well as the emerging technological advances of 4G and 5G (new-generation mobile phones that will use 5G), have caused a significant increase in the personal exposure to Radiofrequency Electromagnetic Fields (RF-EMF), and as a consequence, increasing discussions about the possible adverse health effects. The main objective of this study was to measure the personal exposure to radiofrequency electromagnetic fields from the Wi-Fi in the university area of German Jordanian University (GJU) and prepare georeferenced maps of the registered intensity levels and to compare them with the basic international restrictions. Spot measurements were made outside the university area at German Jordanian University.

Structural parameters of soft PNIPAM microgel particles as a function of crosslink density.

Hypothesis: The temperature dependences of hydrodynamic radii in thermo-sensitive microgel suspensions, known as collapse curves, are commonly fitted to the benchmark Flory-Rehner theory but parameters obtained often yield little physical insights. Our study of poly(N-isopropylacrylamide) (PNIPAM) microgel suspensions in water is driven by the hypothesis that fitting to Flory-Rehner theory can yield meaningful parameters that separate into ones that are insensitive to crosslink density or deuteration and ones that are not.

Experiments: Dynamic light scattering (DLS) and rheology experiments were done on 8 microgel variants, protonated and deuterated PNIPAM for four crosslink densities, synthesized under otherwise identical conditions.