Rapid Prototyping of a Nanoparticle Concentrator Using a Hydrogel Molding Method

Nanoparticle (NP) concentration is crucial for liquid biopsies and analysis, and various NP concentrators (NPCs) have been developed. Methods using ion concentration polarization (ICP), an electrochemical phenomenon based on NPCs consisting of microchannels, have attracted attention because samples can be non-invasively concentrated using devices with simple structures. The fabrication of such NPCs is limited by the need for lithography, requiring special equipment and time. To overcome this, we reported a rapid prototyping method for NPCs by extending the previously developed hydrogel molding method, a microchannel fabrication method using hydrogel as a mold. With this, we fabricated NPCs with both straight and branched channels, typical NPC configurations. The generation of ICP was verified, and an NP concentration test was performed using dispersions of negatively and positively charged NPs. In the straight-channel NPC, negatively and positively charged NPs were concentrated >50-fold and >25-fold the original concentration, respectively. To our knowledge, this is the first report of NP concentration via ICP in a straight-channel NPC. Using a branched-channel NPC, maximum concentration rates of 2.0-fold and 1.7-fold were obtained with negatively and positively charged NPs, respectively, similar to those obtained with NPCs fabricated through conventional lithography. This rapid prototyping method is expected to promote the development of NPCs for liquid biopsy and analysis.

In situ synthesis of methane using Ag–GDC composite electrodes in a tubular solid oxide electrolytic cell: new insight into the role of oxide ion removal

In situ synthesis of methane in a single-temperature zone SOEC in the absence of any methanation catalyst is a completely electrochemical phenomenon governed by the thermodynamic equilibrium of various reactions.

Nanoscale morphological evolution of monocrystalline Pt surfaces during cathodic corrosion

This paper studies the cathodic corrosion of a spherical single crystal of platinum in an aqueous alkaline electrolyte, to map out the detailed facet dependence of the corrosion structures forming during this still largely unexplored electrochemical phenomenon. We find that anisotropic corrosion of the platinum electrode takes place in different stages. Initially, corrosion etch pits are formed, which reflect the local symmetry of the surface: square pits on (100) facets, triangular pits on (111) facets, and rectangular pits on (110) facets. We hypothesize that these etch pits are formed through a ternary metal hydride corrosion intermediate. In contrast to anodic corrosion, the (111) facet corrodes the fastest, and the (110) facet corrodes the slowest. For cathodic corrosion on the (100) facet and on higher-index surfaces close to the (100) plane, the etch pit destabilizes in a second growth stage, by etching faster in the (111) direction, leading to arms in the etch pit, yielding a concave octagon-shaped pit. In a third growth stage, these arms develop side arms, leading to a structure that strongly resembles a self-similar diffusion-limited growth pattern, with strongly preferred growth directions.

Polymeric suspensions viscosity evolution under a constant electric field

The present paper illustrates the effect of the coupling of an electric field with a shear field on a suspension ER. When the suspensions are simultaneously under flow and under the influence of a low electric field organized into packed lamellar formations, the shear stress increases with the increase of the higher polarisable particle concentration both in the electrostatic and hydrodynamic forces. In the absence of an electric field, the flow, alone, produces no segregation.The curves obtained after analyzes illustrate the changes on the shear viscosity under the simultaneous effect of an electric field and shear rate of the three suspensions study. We also observed the appearance of a white foam layer at the experimental apparatus which results in the electrochemical phenomenon due to some values of electric field. The latter can be exploited for a possible further research.

A THERMODYNAMIC MECHANISM BEHIND AN ACTION POTENTIAL AND BEHIND ANESTHESIA

It has been proposed that an action potential going through a nerve cell is not merely an electrochemical phenomenon, but also involves a traveling wave of compression and partial freezing of the lipid bilayer membrane. Below we present the results of experiments that are intended to discriminate between the electrochemical and the thermodynamic mechanism. We find that a nerve that is affected by an anesthetic can nevertheless reach the same compound action potential as an unaffected nerve when it receives a higher stimulus voltage. The result is hard to reconcile with the electrochemical Hodgkin–Huxley model and consistent with the thermodynamic mechanism.