Plasmons in Pb nanowire arrays on Si(557): Between one and two dimensions

The plasmon dispersion in arrays of nanowires of Pb close to an average Pb coverage of one monolayer was determined on the Si(557) surface using electron energy loss spectroscopy with both high energy and momentum resolution. While we find purely one-dimensional (1D) plasmon losses at a Pb concentration of 1.31 monolayers (ML), measured with respect to the Si(111) surface concentration, the 1.2 and 1.4 ML coverages exhibit wavelength-dependent transitions from 1D to anisotropic 2D properties. However, due to the high anisotropy in the system at all coverages, the dispersion curves exhibit 1D characteristics in both directions. This behavior seems to be related to the Pb-induced refacetting of the Si(557) surface, which depends on Pb coverage. It changes both effective system sizes and coupling strength between miniterraces. © 2011 American Physical Society.Ministry of Education, Culture, Sports, Science, and Technology, Japa

Water-Soluble Molecularly Imprinted Nanoparticle Receptors with Hydrogen-Bond-Assisted Hydrophobic Binding

Molecularly imprinted nanoparticles (MINPs) were prepared when surfactants with a tripropargylammonium headgroup and a methacrylate-functionalized hydrophobic tail were cross-linked in the micelle form on the surface and in the core in the presence of hydrophobic template molecules. With the surfactants containing an amide bond near the headgroup, the MINPs had a layer of hydrogen-bonding groups in the interior that strongly influenced their molecular recognition. Templates/guests with strong hydrogen-bonding groups in the midsection of the molecule benefited most, especially if the hydrophobe of the template could penetrate the amide layer to reach the hydrophobic core of the cross-linked micelles. The location and the orientation of the hydrophilic groups were also important, as they determined how the template interacted with the surfactant micelles and, ultimately, with the MINP receptors

Effects of Amphiphile Topology on the Aggregation of Oligocholates in Lipid Membranes: Macrocyclic versus Linear Amphiphiles

A macrocyclic and a linear trimer of a facially amphiphilic cholate building block were labeled with a fluorescent dansyl group. The environmentally sensitive fluorophore enabled the aggregation of the two oligocholates in lipid membranes to be studied by fluorescence spectroscopy. Concentration-dependent emission wavelength and intensity revealed a higher concentration of water for the cyclic compound. Both compounds were shown by the red-edge excitation shift (REES) to be located near the membrane/water interface at low concentrations, but the cyclic trimer was better able to migrate into the hydrophobic core of the membrane than the linear trimer. Fluorescent quenching by a water-soluble (NaI) and a lipid-soluble (TEMPO) quencher indicated that the cyclic trimer penetrated into the hydrophobic region of the membrane more readily than the linear trimer, which preferred to stay close to the membrane surface. The fluorescent data corroborated with the previous leakage assays that suggested the stacking of the macrocyclic cholate trimer into transmembrane nanopores, driven by the strong associative interactions of water molecules inside the macrocycles in a nonpolar environment

Hydrographic features of the water column immediately prior to the start of each bioassay (BA).

<p>Water column profiles were measured with calibrated sensors attached to the CTD rosette. At station A and station B in April (BA1 and BA2) and August (BA3 and BA4). The lack of PAR in BA1 was because the bioassay was started at night. The low PAR in BA4 was due to extensive cloud cover.</p

Phytoplankton community compositions in different treatments in the four bioassays at t = 48 hours determined by ChemTax V 1.95.

<p>NG: no grazers, SB: surface+bottom.</p

Linear relationship between F_o and chl <i>a</i> concentration (µg L⁻¹) after 48 hrs incubation in different bioassays.

<p>R² = 0.6216, <i>p</i><0.001 in BA1, R² = 0.6202, <i>p</i><0.05 in BA2, R² = 0.3503, <i>p</i><0.01in BA3 and R² = 0.5488, <i>p</i><0.05 in BA4.</p

Tunable Fusion and Aggregation of Liposomes Triggered by Multifunctional Surface-Cross-Linked Micelles

Water-soluble organic nanoparticles were prepared by cross-linking the micelles of a tripropargylated cationic surfactant by a diazide cross-linker in the presence of Cu­(I) catalysts. The nanoparticles were decorated with hydrophilic ligands of different lengths on the surface. By interacting with negatively charged liposomes through tunable electrostatic interactions, these nanoparticles induced fusion and leakage of large unilamellar vesicles (LUVs). Fusion or aggregation of the membranes was highly sensitive to the rigidity and phase structures of the membranes, enabling thermally gated fusion to occur within a very narrow window of temperature change

Study area and bathymetry for the mechanisms controlling hypoxia program in the northern Gulf of Mexico.

<p>The 10, 20, 50 and 100</p

Average σPSII and τQA values measured in the four bioassays.

<p>Data shown are the means ± S.E. * indicate significant difference compared with the control group.</p

Initial pigment / chl <i>a</i> ratios for the different phytoplankton groups used for ChemTax V1.95.

<p>Diat  =  diatoms, Dino  =  dinoflagellates, Cyan  =  cyanobacteria, Crypto  =  cyptophytes, Prymn  =  prymnesiophytes, Pelago  =  pelagophytes, Prasino  =  prasinophytes, Chloro  =  chlorophytes. See text (methods) for pigment names.</p