DNA double helices for single molecule electronics

The combination of self-assembly and electronic properties as well as its true nanoscale dimensions make DNA a promising candidate for a building block of single molecule electronics. We argue that the intrinsic double helix conformation of the DNA strands provides a possibility to drive the electric current through the DNA by the perpendicular electric (gating) field. The transistor effect in the poly(G)-poly(C) synthetic DNA is demonstrated within a simple model approach. We put forward experimental setups to observe the predicted effect and discuss possible device applications of DNA. In particular, we propose a design of the single molecule analog of the Esaki diode.Comment: 4 pages, 4 figur

The effects of de-energizing ties in organizations and how to manage them

PublishedThis is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.n/

Destructive de-energizing relationships: How thriving buffers their effect on performance.

PublishedThis is the author accepted manuscript. The final version is available from American Psychological Association via the DOI in this record.In this paper, we establish the relationship between de-energizing relationships and individual performance in organizations. To date, the emphasis in social network research has largely been on positive dimensions of relationships despite literature from social psychology revealing the prevalence and detrimental impact of de-energizing relationships. In 2 field studies, we show that de-energizing relationships in organizations are associated with decreased performance. In Study 1, we investigate how de-energizing relationships are related to lower performance using data from 161 people in the information technology (IT) department of an engineering firm. In Study 2, in a sample of 439 management consultants, we consider whether the effects of de-energizing relationships on performance may be moderated by the extent to which an individual has the psychological resource of thriving at work. We find that individuals who are thriving at work are less susceptible to the effects of de-energizing relationships on job performance. We close by discussing implications of this research

Self-assembled guanine ribbons as wide-bandgap semiconductors

We present a first principle study about the stability and the electronic properties of a new biomolecular solid-state material, obtained by the self-assembling of guanine (G) molecules. We consider hydrogen-bonded planar ribbons in isolated and stacked configurations. These aggregates present electronic properties similar to inorganic wide-bandgap semiconductors. The formation of Bloch-type orbitals is observed along the stacking direction, while it is negligible in the ribbon plane. Global band-like conduction may be affected by a dipole-field which spontaneously arises along the ribbon axis. Our results indicate that G-ribbon assemblies are promising materials for biomolecular nanodevices, consistently with recent experimental results.Comment: 7 pages, 3 figures, to be published in Physica

Classical properties of low-dimensional conductors: Giant capacitance and non-Ohmic potential drop

Electrical field arising around an inhomogeneous conductor when an electrical current passes through it is not screened, as distinct from 3D conductors, in low-dimensional conductors. As a result, the electrical field depends on the global distribution of the conductivity sigma(x) rather than on the local value of it, inhomogeneities of sigma(x) produce giant capacitances C(omega) that show frequency dependence at relatively low omega, and electrical fields develop in vast regions around the inhomogeneities of sigma(x). A theory of these phenomena is presented for 2D conductors.Comment: 5 pages, two-column REVTeX, to be published in Physical Review Letter

Spin effects in single-electron tunneling in magnetic junctions

Spin dependent single electron tunneling in ferromagnetic double junctions is analysed theoretically in the limit of sequential tunneling. The influence of discrete energy spectrum of the central electrode (island)on the spin accumulation, spin fluctuations and tunnel magnetoresistance is analysed numerically in the case of a nonmagnetic island. It is shown that spin fluctuations are significant in magnetic as well as in nonmagnetic junctions.Comment: 14 pages, 3 eps-figures include

Quantum transport through a DNA wire in a dissipative environment

Electronic transport through DNA wires in the presence of a strong dissipative environment is investigated. We show that new bath-induced electronic states are formed within the bandgap. These states show up in the linear conductance spectrum as a temperature dependent background and lead to a crossover from tunneling to thermal activated behavior with increasing temperature. Depending on the strength of the electron-bath coupling, the conductance at the Fermi level can show a weak exponential or even an algebraic length dependence. Our results suggest a new environmental-induced transport mechanism. This might be relevant for the understanding of molecular conduction experiments in liquid solution, like those recently performed on poly(GC) oligomers in a water buffer (B. Xu et al., Nano Lett 4, 1105 (2004)).Comment: 5 pages, 3 figure

Critical behavior of cascading failures in overloaded networks

In recent years, research on spatial networks has become of widespread interest, with the focus on analyzing critical phenomena that can dramatically affect real systems via cascading failures and abrupt collapses. Here, we study the breakdown of a spatial network having a characteristic link-length due to overloads and the cascading failures that are triggered by failures of a fraction of links. While such breakdowns have been studied extensively, the critical exponents and the universality class of this phase transition have not been found. Here, we show indications that this transition has features and critical exponents which are the same as those of interdependent network systems, suggesting that both systems are in the same universality class. We find different abrupt transitions at the steady state, for different spatial embedding strength. For the weakly embedded systems (i.e., link-lengths of the order of the system size) we observe a mixed-order transition where the order parameter collapses with time in a long plateau shape. On the other hand, in strongly embedded systems (relatively short links), we find a pure first order transition which involves nucleation and growth of damage. System behavior in both limits is analogous to that observed in interdependent networks.Comment: 7 pages, 6 figure

Electronic transport in DNA

We study the electronic properties of DNA by way of a tight-binding model applied to four particular DNA sequences. The charge transfer properties are presented in terms of localization lengths (crudely speaking, the length over which electrons travel). Various types of disorder, including random potentials, are employed to account for different real environments. We have performed calculations on poly(dG)-poly(dC), telomeric-DNA, random-ATGC DNA, and l-DNA. We find that random and l-DNA have localization lengths allowing for electron motion among a few dozen basepairs only. A novel enhancement of localization lengths is observed at particular energies for an increasing binary backbone disorder. We comment on the possible biological relevance of sequence-dependent charge transfer in DNA