Features of growth for<i> Mytilus trossulus</i> (Bivalvia: Mytilidae) in various conditions of habitat in the Tauiskaya Bay of the Okhotsk Sea

Biology of Mytilus trossulus is investigated in the Vesyolaya Cove, the Tauiskaya Bay on June 16 - September 20, 2011 within experimental studies of its cultivation ability in severe conditions of the northern Okhotsk Sea. In case of so called Spanish cultivation technology or its White Sea modification, the mussels grow to the commercial size (35 mm) in 3-4 seasons. To decrease this time to 1-2 seasons, the breeding technology is applied with the mussels collecting from the littoral substrate and their further breeding in hanged collectors. The mussels growth rate is evaluated both on the littoral substrate and in the collectors. The growth rate becomes lower after the mussels transfer from the littoral substrate to the hanged collectors but increases intensively after their transfer from the collectors to the littoral substrate, being higher that for the originally littoral mollusks. The growth rate dependence on size and age of the mussels is considered

Local electronic structure of the peptide bond probed by resonant inelastic soft X-ray scattering.

The local valence orbital structure of solid glycine, diglycine, and triglycine is studied using soft X-ray emission spectroscopy (XES), resonant inelastic soft X-ray scattering (RIXS) maps, and spectra calculations based on density-functional theory. Using a building block approach, the contributions of the different functional groups of the peptides are separated. Cuts through the RIXS maps furthermore allow monitoring selective excitations of the amino and peptide functional units, leading to a modification of the currently established assignment of spectral contributions. The results thus paint a new-and-improved picture of the peptide bond, enhance the understanding of larger molecules with peptide bonds, and simplify the investigation of such molecules in aqueous environment

Promoted Exchange Reaction between Alkanethiolate Self-Assembled Monolayers and an Azide-Bearing Substituent

The possibility of ultraviolet (UV) light promoted exchange reaction (UVPER) between the primary alkanethiolate (AT) self-assembled monolayers (SAMs) and an azide-functionalized substituent (12-azido-1-dodecanethiol, C12N3), capable of click reaction with ethynyl-bearing species, is demonstrated. This reaction resulted in the mixed AT/C12N3 films, with the portion of C12N3 precisely controlled by selection of a suitable UV dose. As the primary matrix, either nonsubstituted or oligo(ethylene glycol) (OEG)-substituted AT SAMs were used, targeting mixed SAMs of chemical and biological significance. To demonstrate the flexibility of the approach, UV light with two different wavelengths (254 and 375 nm) was used, applied to the nonsubstituted and OEG-substituted AT SAMs, respectively. The surface density of the chemically active azide groups embedded in the nonreactive primary matrix could be varied according to the composition of the mixed SAMs, as demonstrated by the subsequent click reaction between these SAMs and several representative functional moieties bearing a suitable group for the click reaction with azide. For the OEG-AT/C12N3 films, this resulted in the preparation of templates for specific protein adsorption, comprising biotin-bearing moieties embedded in the protein-repelling OEG-AT matrix. The density of the biotin receptors was varied according to the density of the C12N3 moieties. The templates exhibited much higher affinity to the specific protein (avidin) as compared to a nonspecific one. The surface density of avidin could be varied in accordance with the density of the biotin receptors, i.e., directly controlled by the UV dose within the UVPER procedure. The entire approach was extended to lithography, relying on a commercial maskless UV lithography setup. Representative gradient patterns of specifically attached avidin in the protein-repelling OEG-AT matrix were fabricated

N-heterocyclic carbenes : the design concept for densely packed and thermally ultra-stable aromatic self-assembled monolayers

Self-assembled monolayers (SAMs) of N-heterocyclic carbenes (NHCs) on metal substrates are currently one of the most promising systems in context of molecular-scale engineering of surfaces and interfaces, crucial for numerous applications. Interest in NHC SAMs is mainly driven by their assumingly higher thermal stability compared to thiolate SAMs most broadly used at the moment. Most of the NHC SAMs utilize imidazolium as an anchoring group for linking molecules to the metal substrate via carbene C atom. It is well established in the literature that standing up and stable NHC SAMs are built only when using bulky side groups attached to nitrogen heteroatoms in imidazolium moiety, which, however, leads to monolayers exhibiting much lower packing density compared to thiolate SAMs. Here, by combined X-ray photoelectron spectroscopy, near-edge X-ray absorption fine structure spectroscopy, and temperature-programmed secondary ion mass spectrometry analysis, we demonstrate that using NHCs with small methyl side groups in combination with simple, solution-based preparation leads to the formation of aromatic monolayers exhibiting at least doubled surface density, upright molecular orientation, and ultra-high thermal stability compared to the NHC SAMs reported before. These parameters are crucial for most applications, including, in particular, molecular and organic electronics, where aromatic SAMs serve either as a passive element for electrode engineering or as an active part of organic field effect transistors and novel molecular electronics devices

Electronic structure and polymerization of a self-assembled monolayer with multiple arene rings

We find evidence of intermolecular interactions for a self-assembled monolayer (SAM) formed from a large molecular adsorbate, [1,1′;4′,1′′-terphenyl]-4,4′′-dimethanethiol, from the dispersion of the molecular orbitals with changing wave vector k. With the formation self-assembled molecular (SAM) layer, the molecular orbitals hybridize to electronic bands, with indications of significant band dispersion of the unoccupied molecular orbitals. The electronic structure is also seen to be dependent upon temperature, and cross linking between the neighbor molecules, indicating that the electronic structure may be subtly altered by changes in molecular conformation and packing

Systematic experimental study of quantum interference effects in anthraquinoid molecular wires

In order to translate molecular properties in molecular-electronic devices, it is necessary to create design principles that can be used to achieve better structure-function control oriented toward device fabrication. In molecular tunneling junctions, cross-conjugation tends to give rise to destructive quantum interference effects that can be tuned by changing the electronic properties of the molecules. We performed a systematic study of the tunneling charge-transport properties of a series of compounds characterized by an identical cross-conjugated anthraquinoid molecular skeleton but bearing different substituents at the 9 and 10 positions that affect the energies and localization of their frontier orbitals. We compared the experimental results across three different experimental platforms in both single-molecule and large-area junctions and found a general agreement. Combined with theoretical models, these results separate the intrinsic properties of the molecules from platform-specific effects. This work is a step towards explicit synthetic control over tunneling charge transport targeted at specific functionality in (proto-) devices