Evidence of Faradaic Reactions in Electrostatic Atomizers

Abstract

Any rational theory of electrostatic atomizers (EAs) would require a detailed understanding of the nature of the polarized layer near the electrode, since this is the source of the electric charge carried by the jets issued from the EAs. The polarized layer either is driven out as the electrically-driven Smoluchowski flow and/or entrained by the viscous shear imposed by the bulk flow. The standard Gouy-Chapman theory of polarized diffuse layers implies zero electric current passing across the layer, which is impossible to reconcile with the fact that there are leak currents in the EAs. Here, we show that the electric current through the EA is controlled by faradaic reactions at the electrodes. The experiments were conducted with stainless steel or brass pin-like cathodes and three different anode (the conical nozzle) materials, which were copper, stainless steel, and brass. The different electrode materials resulted in different spray, leakage, and total currents in all the cases. Accordingly, it is shown that the total electric current generated by EAs can be controlled by the cathode and anode materials, i.e., by faradaic reactions on them. This lays the foundation for a more detailed understanding and description of the operation of EAs.

Stimuli‐Responsive Cucurbit[n]uril‐Mediated Host‐Guest Complexes on Surfaces

“…[74] Also tryptophan (Trp) based protein immobilization was studied on this type of CB[8]-pseudorotaxane based SAMs. [91,95,97] Specificity and reversibility was typically verified in the experiments to confirm envisioned host-guest interactions to occur. In a recent study we prepared a focused set of integrin-targeting knottin variants with distinct numbers of tryptophans to vary affinities for the pseudorotaxane-based CB [8] SAMs.…”

“…[67] We have reported successful ways to anchor proteins, viruses, bacteria and cells using CB[n]-mediated complexation on SAMs. [73,74,[88][89][90][91][92][93][94][95][96][97] A focus point has been to employ siteselectively guest-labeled proteins, which can be used for oriented positioning of proteins, as for example demonstrated on CB [7] SAMs. Mono-and divalent ferrocenylated yellow fluorescent protein were prepared and these formed stable inclusion complexes on CB [7] SAMs (method Figure 5b).…”

“…In a recent study we prepared a focused set of integrin-targeting knottin variants with distinct numbers of tryptophans to vary affinities for the pseudorotaxane-based CB [8] SAMs. [91,95] The genetically engineered knottin constructs are able to simultaneously bind integrins and MV 2 + /CB [8] via one, two, three or four Trp heteroternary complexations. [95] Binding studies showed slightly higher binding affinities for knottins with a larger number of tryptophan residues while an increased extent of multilayer formation for the higher valent constructs, which we attributed to homoternary complex formation between tryptophans of different knottins and CB [8].…”

“…[91,95] The genetically engineered knottin constructs are able to simultaneously bind integrins and MV 2 + /CB [8] via one, two, three or four Trp heteroternary complexations. [95] Binding studies showed slightly higher binding affinities for knottins with a larger number of tryptophan residues while an increased extent of multilayer formation for the higher valent constructs, which we attributed to homoternary complex formation between tryptophans of different knottins and CB [8]. Tri-and tetravalent knottin constructs yielded the largest extent of adhered cell elongation and more pronounced focal adhesion formation.…”

“…Tri-and tetravalent knottin constructs yielded the largest extent of adhered cell elongation and more pronounced focal adhesion formation. [95] As an alternative to integrin-receptor mediated adhesion of cells on CB[8] SAMs, we have recently metabolically expressed naphthol moieties on the outer surface of non-adherent Jurkat cells (Figure 11c). [93] Specific host-guest was demonstrated on surfaces and the method potentially allows for programmable supramolecular interactions with spatial and temporal control over cell adhesion as well.…”