tion of individual protein molecules or complexes than an extended, homogeneous surface. Of course, this hypothesis needs to be tested by biological activity. ExperimentalSize-selected metal (Au) clusters, with size between 1 and 100 atoms, were generated by an RF (radio-frequency) magnetron sputtering, gas condensation [20,21] cluster beam source and mass selected to within 5 % by a novel, lateral time-of-flight mass filter to control the cluster size, as described previously [22]. The energetic beam of ionized Au clusters was deposited on a graphite substrate with sufficient kinetic energy to ªpinº the clusters to their individual points of impact on the surface. The underlying mechanism of pinning is the displacement of a surface carbon atom to create a reactive binding site which prevents the characteristic diffusion and aggregation of clusters observed at lower incident energies [15,16]. In this work we found that such monodispersed cluster films were stable not only at room temperature but also at temperatures up to 200 C. They are also stable when placed in an autoclave (130 C for 2 h in high pressure steam) to sterilize the surface. The Au 17 + clusters were produced with an Ar flow of 60 sccm and a He flow of 25 sccm (total gas pressure of 0.4 mbar). Typical sputtering parameters were: RF power 25 W; self-bias voltage of the target 372 V. The cluster samples were imaged in ambient conditions with a bench-top STM (DME Rasterscope 4000). Typical imaging parameters were 0.4 V and 0.4 nA (using mechanically cut Pt/Ir tips). All AFM measurements were collected from a Digital Instruments DI3100 equipped with a Nanoscope IIIa controller and a liquid cell holder. Commercial oxide sharpened silicon nitride tips with nominal spring constant of either 0.38 or 0.60 N m ±1 were used for imaging.

No abstract

When we consider the problem of finding influential nodes for information diffusion in a large-scale social network based on the Independent Cascade Model (ICM), we need to compute the expected number of nodes influenced by a given set of nodes. However, a good estimate of this quantity needs a large amount of computation in the ICM. In this paper, we propose two natural special cases of the ICM such that a good estimate of this quantity can be efficiently computed. Using real large-scale social networks, we experimentally demonstrate that for extracting influential nodes, the proposed models can provide novel ranking methods that are different from the ICM, typical methods of social network analysis, and "PageRank" method. Moreover, we experimentally demonstrate that when the propagation probabilities through links are small, they can give good approximations to the ICM for finding sets of influential nodes.

We address the combinatorial optimization problem of finding the most influential nodes on a large-scale social network for two widely-used fundamental stochastic diffusion models. The past study showed that a greedy strategy can give a good approximate solution to the problem. However, a conventional greedy method faces a computational problem. We propose a method of efficiently finding a good approximate solution to the problem under the greedy algorithm on the basis of bond percolation and graph theory, and compare the proposed method with the conventional method in terms of computational complexity in order to theoretically evaluate its effectiveness. The results show that the proposed method is expected to achieve a great reduction in computational cost. We further experimentally demonstrate that the proposed method is much more efficient than the conventional method using largescale real-world networks including blog networks.Responsible editor: R. Bayardo. M. Kimura (B)

The directed self-assembly of diblock copolymers offers unique routes for the design and fabrication of well-ordered arrays of nanoscopic structures. However, generating arrays with long-range order and few defects has been a difficult goal to achieve without extended thermal annealing processes. Here, a simple, one-step route, based on the flow of a solution within a droplet pinned to a surface coupled with solvent evaporation, is shown where highly oriented, ordered arrays of nanoscopic cylindrical domains of a block copolymer can be produced over large distances (tens of microns). Hexagonal arrays of the cylindrical domains of block copolymers are shown to orient parallel to the film surface and in the direction of an evaporation-induced flow, producing morphologies with very long-range order. This solution casting process, that naturally couples two orthogonal fields, is easily transferable to blade-and dip-coating processes that are routinely used to prepare thin films. Thus, a simple route is shown, by which the barrier to long-range order in arrays of nanoscopic elements can be overcome, providing valuable insight for designing addressable media.

Ultraviolet light-emitting diodes (UV-LEDs) have started replacing UV lamps. The power per LED of high-power LED products has reached 12 W (14 A), which is 100 times the values observed ten years ago. In addition, the cost of these high-power LEDs has been decreasing. In this study, we attempt to understand the technologies and potential of UV-LEDs.

Supply of safe fresh water is currently one of the most important global issues. Membranes technologies are essential to treat water efficiently with low costs and energy consumption. Here, the development of self‐organized nanostructured water treatment membranes based on ionic liquid crystals composed of ammonium, imidazolium, and pyridinium moieties is reported. Membranes with preserved 1D or 3D self‐organized sub‐nanopores are obtained by photopolymerization of ionic columnar or bicontinuous cubic liquid crystals. These membranes show salt rejection ability, ion selectivity, and excellent water permeability. The relationships between the structures and the transport properties of water molecules and ionic solutes in the sub‐nanopores in the membranes are examined by molecular dynamics simulations. The results suggest that the volume of vacant space in the nanochannel greatly affects the water and ion permeability.

Purpose: MicroRNAs (miRNA) are small noncoding RNAs thought to be involved in physiologic and developmental processes by negatively regulating the expression of target genes. Little is known about the role of miRNAs in normal and cancer cells. It is possible that deregulation of miRNA may contribute to the oncogenesis of some cancers. We studied the expression level of the miRNA processing enzyme (DICER1, DGCR8, and RNASEN) in esophageal squamous cell carcinoma (ESCC). Experimental Design: The expression levels of DICER1, DGCR8, and RNASEN mRNA in 73 ESCC tissues were compared with that in corresponding normal esophageal epithelium by Taqman real-time reverse-transcription PCR.We also examined RNASEN protein expression in 27 cell lines. The role of RNASEN in cell proliferation in ESCC cells was assessed by small interfering RNA. Paraffin sections of ESCC patients were immunohistochemically investigated. Results: We found that RNASEN expression levels were enhanced in a fraction of esophageal cancers. Multivariate Cox regression analysis showed that the prognostic effect of RNASEN (P = 0.0036) seems to be independent of disease stage (P = 0.0060). Knockdown of RNASEN in esophageal cancer cell lines resulted in a 46% to 85% reduction in cell number. In an immunohistochemical study, the intensity of RNASEN expression was often increased in the tumor compared with that in normal epithelium. Conclusions: The relationship between the RNASEN expression and the prognosis of the ESCC patients warrants a further study on the role of miRNA and tumor progression.