Optimal paths in disordered complex networks

We study the optimal distance in networks, l(opt), defined as the length of the path minimizing the total weight, in the presence of disorder. Disorder is introduced by assigning random weights to the links or nodes. For strong disorder, where the maximal weight along the path dominates the sum, we find that l(opt) approximately N(1/3) in both Erdos-Rényi (ER) and Watts-Strogatz (WS) networks. For scale-free (SF) networks, with degree distribution P(k) approximately k(-lambda), we find that l(opt) scales as N((lambda-3)/(lambda-1)) for 3 or =4. Thus, for these networks, the small-world nature is destroyed. For 2相似文献   

Hopf algebras of types which give rise to certain invariants of knots, links and 3-manifolds

In this paper we determine when Lusztig's has all the desired properties necessary to define invariants of knots, links and 3-manifolds. Specifically, we determine when it is ribbon, unimodular and factorizable. We also compute the integrals and distinguished elements involved.

     

The role of the electrostatic interaction in shifting the vibrational frequencies for two adsorbed molecules

We use a simple model to compute the shift of the vibrational frequencies of two adsorbed molecules as a function of inter-molecular distance, and various molecular and metal parameters. We assume that the atoms posses static and dynamic charges and the molecule has an electronic polarizability. The chemical bonds are described by Morse potentials. The electrostatic interactions are computed by a density functional method. We conclude that the use of vibrating point dipoles and of the image theorem in such calculations is an oversimplification.     

Integral bounds on the strain energy for the traction problem in finite elasticity

For the traction boundary value problem in finite elasticity, a bound is obtained for the total strain energy in terms of the L₂ integral norms of the surface tractions and body forces, under the assumptions that the unstressed body occupies a convex domain and the displacement gradients are sufficiently small.This is an extension of known results in linear (infinitesimal) elasticity into finite elasticity.     

Composite Magnetic and Non‐magnetic Beads as Efficient Solid Supports for Machine‐Aided Oligonucleotide Synthesis

The synthesis of oligodeoxyribonucleotides on composite magnetic and nonmagnetic beads of 4.5 μm with a cleavable and non‐cleaveable linker for biochemical applications is described.     

Kinase Sensing Based on Protein Interactions at the Catalytic Site

The role kinases play in regulating cellular processes makes them potential biomarkers for detecting the onset and prognosis of various diseases, including many types of cancer. Current kinase biosensors, including electrochemical and radiometric methods, rely on sensing the ATP-dependant enzymatic phosphorylation reaction. Here we introduce a new type of interaction-based electrochemical kinase biosensor that does not require any chemical labelling or modification. The basis for sensing is the interactions between the catalytic site of the kinase and the phosphorylation site of its substrate rather than the phosphorylation reaction. We demonstrated this concept with the ERK2 kinase and its substrate protein HDGF, which is involved in lung cancer. A peptide monolayer derived from the HDGF phosphorylation site was adsorbed onto a gold electrode and was used to sense ERK2 without ATP. The sensitivity of the assay was down to 10 nM of ERK2, corresponding with the range of its cellular concentrations. Surface chemistry analysis confirmed that ERK2 was bound to the HDGF peptide monolayer. This increased the permeability of redox-active species through the monolayer and resulted in ERK2 electrochemical sensing. Since our detection approach is based on protein-protein interactions and not on the enzymatic reaction, it can be further utilized for more selective detection of different types of enzymes.     

Switchable assembly of ultra narrow CdS nanowires and nanorods

We report on a simple route for the production of uniform and ultra narrow wurtzite CdS nanowires and nanorods. The nanorods are medium friendly (can exist in organic and aqueous phase) thus making them flexibly suitable for various applications. The centimeter range switchable ordering of the nanowires/rods into 3D microstrings by application of low magnitude DC electric field simply via two graphite electrodes is demonstrated. More sophisticated electrodes can be used for the same system to achieve more complex and fine patterns that can find potential use in nanoelectronics. The aligned microstrings (also wires/rods) show strong polarization dependence along their long axes. The polarized emission with respect to the unique c-axis makes the system suitable for orientation sensitive devices.