Alexander Tokarev

• Clarkson University

The vast majority of light-emitting diode and liquid-crystal displays, solar panels, and windows in residential and industrial buildings use glass panels owing to their high mechanical stability, chemical resistance, and optical properties. Glass surfaces reflect about 4-5% of incident light if no antireflective coating is applied. In addition to e...

In article number 1907422, Sergiy Minko and co‐workers introduce a gravitational fiber drawing method for the fabrication of monofilament nano‐ and microfibers and assemble them in highly ordered 3D arrays with controllable interfiber spacing and fiber angular orientation. The complex 3D constructs are made of fibers with different diameters, draw...

This work introduces a gravity fiber drawing (GFD) method of making single filament nanofibers from polymer solutions and precise alignment of the fibers in 3D scaffolds. This method is advantageous for nanofiber 3D alignment in contrast to other known methods. GFD provides a technology for the fabrication of freestanding filament nanofibers of wel...

We studied NE-4C neural cells differentiation on 2D polycaprolactone (PCL) nanofibrous scaffolds with systematically varied mechanical characteristics of nanofibers while retaining an unchanged fiber alignment, diameter, and chemical composition. Our experiments demonstrated that the nanofibers with enhanced mechanical properties are beneficial for...

In situ characterization of minute amounts of complex fluids is a challenge. Magnetic rotational spectroscopy (MRS) with submicron probes offers flexibility and accuracy providing desired spatial and temporal resolution in characterization of nanoliter droplets and thin films when other methods fall short. MRS analyzes distinct features of the in-p...

Reactive spinning of nano- and microfibers that involves very fast chemical reactions and ion exchange is a challenge for the common methods for nanofiber formation. Herein, we introduce the reactive magnetospinning method. This procedure is based on the magnetic-field-directed collision of ferrofluid droplets with liquid droplets that contain comp...

Magnetic field imaging in living specimens with magnetic nanoparticles as contrasting agents has attracted significant interest in the rapidly developing field of nanomedicine. Developments in this field have also stimulated research into the synthesis and design of functionalized magnetic nanoparticles that find applications in broader areas of ma...

Superparamagnetic nanoparticles have a wide range of applications in materials science and biomedicine, because of their unique response and manipulability under magnetic fields. On page 3761, S. Minko and co-workers review the synthesis of functionalized magnetic nanoparticles, and discuss the various approaches for manipulation and assembly in un...

Optimizing Nafion loading and surface distribution of Nafion in the fuel cell electrode is critical for the fuel cell performance for minimizing ohmic and mass transport overpotentials. An atomic force microscopy method is used here for a qualitative and a quantitative discrimination between the ionomer and Pt in the fuel cell electrode. This work...

Reactive spinning of nano- and microfibers that involves very fast chemical reactions and ion exchange is a challenge for the common methods for nanofiber formation. Herein, we introduce the reactive magnetospinning method. This procedure is based on the magnetic-field-directed collision of ferrofluid droplets with liquid droplets that contain comp...

Reactive spinning of nano- and microfibers that involves very fast chemical reactions and ion exchange is a challenge for the common methods for nanofiber formation. Herein, we introduce the reactive magnetospinning method. This procedure is based on the magnetic-field-directed collision of ferrofluid droplets with liquid droplets that contain comp...

Robust, simple, and scalable touch- and brush-spinning methods for drawing of nanofibers, core-shell nanofibers, and their aligned 2D and 3D meshes using polymer solutions and melts are discussed.

Nothing is known about how plant populations chronically exposed to radiation adapt to a new anthropogenic stressor as engineered nanoparticles (ENP). A set of ecotoxicity tests was conducted with five types of ENP to investigate seed response of Leonurus quinquelobatus populations growing naturally under lowdose irradiation and background conditio...

Nano and microfibers were prepared by spinning a colloidal dispersion of the stabilized magnetic nanoparticles, known as a ferrofluid, in an external magnetic field. During this process, the polymeric nano and microfibers with the average diameters of 0.05–20 µm were drawn in a magnetic field created by a permanent magnet. This technique provides a...

Reactive spinning of nano- and microfibers that involves very fast chemical reactions and ion exchange is a challenge for the common methods for nanofiber formation. Herein, we introduce the reactive magnetospinning method. This procedure is based on the magnetic-field-directed collision of ferrofluid droplets with liquid droplets that contain comp...

Magnetic field assisted assembly is used to fabricate aligned single nanowire mesh-like nanostructured films. Inhomogeneous magnetic field is applied to translocate high aspect ratio silver nanowires from suspensions to the surface of solid supports. The tangential component of the magnetic field vector is rotated in two consecutive steps to arrang...

In-situ characterization of minute amounts of complex fluids is a challenge. Magnetic Rotational Spectroscopy (MRS) with submicron probes offers flexibility and accuracy providing desired spatial and temporal resolution in characterization of nanoliter droplets and thin films when other methods fall short. MRS analyzes distinct features of the in-p...

A method for the generation of remotely reconfigurable anisotropic coatings is developed. To form these coatings, locking magnetic nanoparticles (LMNPs) made of a superparamagnetic core and a two-component polymer shell are employed. Two different polymers form phase-separated coaxial shells. The outer shell provides repulsive interactions between...

Optimized conditions for imaging and spectroscopic/elemental mapping of thin perfluorosulfonic acid (PFSA) ionomer layers in fuel cell electrodes by scanning transmission electron microscopy (STEM) have been investigated. The proper conditions were first identified using model systems of either Nation ionomer-coated nanostructured thin film catalys...

In a non-uniform magnetic field, the droplets of colloids of nickel nanorods and nanobeads aggregate to form a cusp at the droplet surface not deforming the entire droplet shape. When the field is removed, nanorods diffuse away and the cusp disappears. Spherical particles can form cusps in a similar way, but they stay aggregated after the release o...

The enzymogel nanoparticle made of a magnetic core and polymer brush shell demonstrates a novel type of remote controlled phase-boundary biocatalysis that involves remotely directed binding to and engulfing insoluble substrates, high mobility, and stability of the catalytic centers. The mobile enzymes reside in the polymer brush scaffold and shuttl...

A drug-mimicking release process was triggered by a glucose signal resulting in the formation of a negative potential on an electrode modified with PQQ-dependent glucose dehydrogenase. This electrode was coupled with another electrode coated with an Fe(+3)-crosslinked alginate polymer film, which was dissolved upon formation of the negative potenti...

It has been recently reported that for some suspensions of magnetic nanoparticles the transverse proton relaxation rate, R(2), is dependent on the time that the sample is exposed to an applied magnetic field. This time dependence has been linked to the formation of linear aggregates or chains in an applied magnetic field via numerical modeling. It...

Magnetic rotational spectroscopy was employed for rheological analysis of nanoliter droplets of butterfly saliva. Saliva viscosity of butterflies is 4–5 times greater than that of water and similar to that of 30%–40% sucrose solutions at 25 °C. Hence, viscosity stratification would not be expected when butterflies feed on nectar with 30%–40% sugar...

A reversible locking mechanism is established for the generation of anisotropic nanostructures by a magnetic field pulse in liquid matrices by balancing the thermal energy, short-range attractive and long-range repulsive forces, and dipole-dipole interactions using a specially tailored polymer shell of nanoparticles. The locking mechanism is used t...

In situ characterization of minute amounts of fluids that rapidly change their rheological properties is a challenge. In this paper, the rheological properties of fluids were evaluated by examining the behavior of magnetic nanorods in a rotating magnetic field. We proposed a theory describing the rotation of a magnetic nanorod in a fluid when its v...

We report on the development of a multifunctional magnetic rotator that has been built and used during the last five years by two groups from Clemson and Drexel Universities studying the rheological properties of microdroplets. This magnetic rotator allows one to generate rotating magnetic fields in a broad frequency band, from hertz to tens kilohe...

The ability of Lepidoptera, or butterflies and moths, to drink liquids from rotting fruit and wet soil, as well as nectar from floral tubes, raises the question of whether the conventional view of the proboscis as a drinking straw can account for the withdrawal of fluids from porous substrates or of films and droplets from floral tubes. We discover...

The ability of Lepidoptera, or butterflies and moths, to drink liquids from rotting fruit and wet soil, as well as nectar from floral tubes, raises the question of whether the conventional view of the proboscis as a drinking straw can account for the withdrawal of fluids from porous substrates or of films and droplets from floral tubes. We discover...

Imaging of micro- and nanofluidics is a challenge since the size of the channels is so small that the installment of additional optical and mechanical switches is very difficult. The size of the device and associated increase in viscous dissipation constitute another constraint. In response to these limitations, this work proposes and demonstrates...

We have developed a method for laser beam manipulation by using a colloid of nickel nanorods produced by electroplating chemistry. It is shown that the shape of the laser beam passing through a colloid of nickel nanorods can be altered by varying the applied magnetic field. This effect is caused by multiple scattering and diffraction of the laser...

Imaging in micro and nanofluidics is a challenge: the sizes of micro and nanochannels are so small that the installment of additional optical and mechanical switches is almost impossible. Another constrain is the size of the device and associated increase in viscous dissipation. We suggest manipulating the light by using the existing fiber optics a...