/pdf/nanopore-based-fourth-generation-dna-sequencing-technology-2cavwwctne.pdf

Nanopore-based Fourth-generation DNA Sequencing Technology

Bioelectronic materials interface biomolecules, cells, organs, or organisms with electronic devices, and they represent an active and growing field of materials research Protein and peptide nanostructures are ideal bioelectronic materials They possess many of the properties required for biocompatibility across scales from enzymatic to organismal interfaces, and recent examples of supramolecular protein and peptide nanostructures exhibit impressive electronic properties The ability of such natural and synthetic protein and peptide materials to conduct electricity over micrometer to centimeter length scales, however, is not readily understood from a conventional view of their amino acid building blocks Distinct in structure and properties from solid-state inorganic and synthetic organic metals and semiconductors, supramolecular conductive proteins and peptides require careful theoretical treatment and experimental characterization methods to understand their electronic structure In this review, we discuss theory and experimental evidence from recent literature describing the long-range conduction of electronic charge in protein and peptide materials Electron transfer across proteins has been studied extensively, but application of models for such short-range charge transport to longer distances relevant to bioelectronic materials are less well-understood Implementation of electronic band structure and electron transfer formulations in extended biomolecular systems will be covered in the context of recent materials discoveries and efforts at characterization of electronic transport mechanisms

/pdf/going-the-distance-long-range-conductivity-in-protein-and-49od1hlv8y.pdf

Going the Distance: Long-Range Conductivity in Protein and Peptide Bioelectronic Materials

Co-based layered double hydroxide (LDH) catalysts with Fe and Al contents in the range of 15 to 45 at % were synthesized by an efficient coprecipitation method. In these catalysts, Fe3+ or Al3+ ions play an essential role as trivalent species to stabilize the LDH structure. The obtained catalysts were characterized by a comprehensive combination of surface- and bulk-sensitive techniques and were evaluated for the oxygen evolution reaction (OER) on rotating disk electrodes. The OER activity decreased upon increasing the Al content for the Co- and Al-based LDH catalysts, whereas a synergistic effect in Co- and Fe-based LDHs was observed, which resulted in an optimal Fe content of 35 at %. This catalyst was spray-coated on Ni foam electrodes and showed very good stability in a flow-through cell with a potential of approximately 1.53 V at 10 mA cm−2 in 1 m KOH for at least 48 h.

Synergistic Effect of Cobalt and Iron in Layered Double Hydroxide Catalysts for the Oxygen Evolution Reaction.

Carrier thermoelectric-transport theory has recently become of growing interest and numerous thermoelectric-transport models have been proposed for organic semiconductors, due to pressing current issues involving energy production and the environment. The purpose of this review is to provide a theoretical description of the thermoelectric Seebeck effect in organic semiconductors. Special attention is devoted to the carrier concentration, temperature, polaron effect and dipole effect dependence of the Seebeck effect and its relationship to hopping transport theory. Furthermore, various theoretical methods are used to discuss carrier thermoelectric transport. Finally, an outlook of the remaining challenges ahead for future theoretical research is provided.

A review of carrier thermoelectric-transport theory in organic semiconductors

The conductivity of an $n$-type semiconductor has been calculated in the region of low-temperature $T$ and low impurity concentration ${n}_{D}$. The model is that of phonon-induced electron hopping from donor site to donor site where a fraction $K$ of the sites is vacant due to compensation. To first order in the electric field, the solution to the steady-state and current equations is shown to be equivalent to the solution of a linear resistance network. The network resistance is evaluated and the result shows that the $T$ dependence of the resistivity is $\ensuremath{\rho}\ensuremath{\propto}\mathrm{exp}(\frac{{\ensuremath{\epsilon}}_{3}}{\mathrm{kT}})$. For small $K$, ${\ensuremath{\epsilon}}_{3}=(\frac{{e}^{2}}{{\ensuremath{\kappa}}_{0}}){(\frac{4\ensuremath{\pi}{n}_{D}}{3})}^{\frac{1}{3}}(1\ensuremath{-}1.35{K}^{\frac{1}{3}})$, where ${\ensuremath{\kappa}}_{0}$ is the dielectric constant. At higher $K$, ${\ensuremath{\epsilon}}_{3}$ and $\ensuremath{\rho}$ attain a minimum near $K=0.5$. The dependence on ${n}_{D}$ is extracted; the agreement of the latter and of ${\ensuremath{\epsilon}}_{3}$ with experiment is satisfactory. The magnitude of $\ensuremath{\rho}$ is in fair agreement with experiment. The influence of excited donor states on $\ensuremath{\rho}$ is discussed.

Impurity Conduction at Low Concentrations.

Binary phase square spiral zone plates (BPSSZPs), a special type of binary phase vortex lenses, are introduced to generate focused optical vortices showing square symmetry. The numerical solution and fabrication method, as well as the experimental results are given. Different from conventional vortex lenses, these BPSSZPs produce focused vortices with small topological charge following a modulo-4 transmutation rule. In addition, the central diffracted image rotates in the vicinity of the focal plane. These interesting properties suggest that BPSSZPs might become key components for many potential applications such as optical image processing and quantum computation.

Square optical vortices generated by binary spiral zone plates

Charge carrier hopping transport is generally taken from Miller-Abrahams and Marcus transition rates. Based on the Miller-Abrahams theory and nearest-neighbour range hopping theory, Apsley and Hughes developed a concise calculation method (A-H method) to study the hopping conduction in disordered systems. Here, we improve the A-H method to investigate the charge carrier hopping transport by introducing polaron effect and electric field based on Marcus theory and variable-range hopping theory. This improved method can well describe the contribution of polaron effect, energetic disorder, carrier density, and electric field to the charge carrier transport in disordered organic semiconductor. In addition, the calculated results clearly show that the charge carrier mobility represents different polaron effect dependence with the polaron activation energy and decreases with increasing electric field strength for large fields.

Charge carrier hopping transport based on Marcus theory and variable-range hopping theory in organic semiconductors

We introduce circular Fibonacci gratings (CFGs) that combine the concept of circular gratings and Fibonacci structures. Theoretical analysis shows that the diffraction pattern of CFGs is composed of fractal distributions of impulse rings. Numerical simulations are performed with two-dimensional fast Fourier transform to reveal the fractal behavior of the diffraction rings. Experimental results are also presented and agree well with the numerical results. The fractal nature of the diffraction field should be of great theoretical interest, and shows potential to be further developed into practical applications, such as in laser measurement with wideband illumination.

Circular Fibonacci gratings

Conventional diffraction gratings composed of a series of equally spaced slits suffer from wavelength overlapping caused by high-order diffraction. Here modulated groove position gratings (MGPGs) are proposed to significantly suppress the high diffraction orders. Both numerical solution and experimental results demonstrate the effectiveness of MGPGs. The suppression ratio is determined by the number of grating grooves used. By using an MGPG with 10,000 grooves, a suppression ratio as high as 18,000 can be obtained. In addition, the minimum linewidth is kept to 1/4 of the grating period, which enables grating realization with high line density employing today’s nanofabrication technology. Our results should be of great interest in both diffraction grating theory and applications, particularly due to MGPGs’ applicability in a wide wavelength range and realizability with high line density.

High-order diffraction suppression using modulated groove position gratings

Vortex transmutation was predicted to take place when vortices interact with systems possessing discrete rotational symmetries of finite order [Phys. Rev. Lett.95, 123901 (2005)]. Here we report what is believed to be the first experimental demonstration of vortex transmutation. We show that in free space, by simply inserting polygonal lenses into the optical path, the central vorticity of a coaxially incident optical vortex can be changed following the modular transmutation rule. We generate the wavefront at the exit face of the lenses with computer generated holograms and measure the output vorticity using the interference patterns at the focal plane. The results agree well with theoretical predictions.

Nan Gao

Papers

Square optical vortices generated by binary spiral zone plates

Charge carrier hopping transport based on Marcus theory and variable-range hopping theory in organic semiconductors

Circular Fibonacci gratings

High-order diffraction suppression using modulated groove position gratings

Experimental demonstration of free-space optical vortex transmutation with polygonal lenses.