Surface-enhanced Raman spectroscopy (SERS) of gold nanorods in cetyltrimethylammonium bromide solution has been used to analyze the interfacial surfactant structure based on the distance-dependent electromagnetic enhancement. The spectra were consistent with a surfactant bilayer oriented normal to the surface. As the surfactant concentration was reduced, a structural transition in the surfactant layer was observed through a sudden increase in the signal from the alkane chains. The structural transition was shown to influence the displacement of the surfactant layer by thiolated poly(ethylene glycol). The monodisperse and thoroughly characterized gold nanorod samples yield consistent enhancement factors that were compared to electromagnetic simulations.

The strong cetyltrimethylammonium bromide (CTAB) surfactant responsible for the synthesis and stability of gold nanorod solutions complicates their biomedical applications. The critical parameter to maintain nanorod stability is the ratio of CTAB to nanorod concentration. The ratio is approximately 740,000 as determined by chloroform extraction of the CTAB from a nanorod solution. A comparison of nanorod stabilization by thiol-terminal PEG and by anionic polymers reveals that PEGylation results in higher yields and less aggregation upon removal of CTAB. A heterobifunctional PEG yields nanorods with exposed carboxyl groups for covalent conjugation to antibodies with the zero-length carbodiimide linker EDC. This conjugation strategy leads to approximately two functional antibodies per nanorod according to fluorimetry and ELISA assays. The nanorods specifically targeted cells in vitro and were visible with both two-photon and confocal reflectance microscopies. This covalent strategy should be generally applicable to other biomedical applications of gold nanorods as well as other gold nanoparticles synthesized with CTAB.

Plasmonic nanowires with sub-100-nm rectangular cross sections were found to exhibit a strong transverse plasmon peak at visible wavelengths. By correlating atomic force microscopy measurements of individual nanobelts with their dark-field scattering spectra, it is seen that the transverse peak tunes with cross-sectional aspect ratio. Simulations revealed that the scattering plasmonic modes are transverse antisymmetric excitations across the nanobelt width. Unlike larger diameter silver nanowires, these nanobelts exhibit sharp, tunable plasmon resonances similar to those of nanoparticles.

Twenty-five species and three subspecies of the family Thyasiridae (Bivalvia: Lucinacea) are described from the deep Atlantic. They belong to two genera and five subgenera. Eleven of the species and all of the subspecies are described for the first time. The number of demibranchs in the gill and shape of the lobes of the lateral body pouches are characteristic features which are additionally used to clarify taxonomic divisions that have been previously based on shell features alone. One species, Axinus grandis Verrill & Bush (1898), is thought to be the sole living representative of the predominantly Tertiary fossil genus Axinus Sowerby (1821). This genus has been regarded by most previous authors as a synonym of Thyasira Leach (1818). Axinus grandis , as here defined, is morphologically distinct from all other thyasirids and possesses primitive characters. It shows affinities to the lucinacean family Ungulinidae, suggesting that the Thyasiridae may have an origin close to the ungulinid stem. The morphology of the species described here is extremely conservative, all sharing a number of key features. The most important of these is the form of the lateral body pouches. Shell shape and morphology relate in part to different life habits. Some species which have vertically elongate shape are probably immobile deep-burrowers, while others, principally the smallest species, which are horizontally elongate are adapted for a more active existence. All are infaunal. The deep-water species are thought to be pre-adapted to life at depth through their ability to inhabit impoverished deoxygenated habitats. Few morphological differences could be detected between the populations of species that occur in both shallow and deep waters. The small size of all but a few species may be one of their greatest adaptive features. The greatest reduction in size and greatest simplification of morphology are seen in species of the subgenera Thyasira and Parathyasira . The subgenera Axinulus and Mendicula show the greatest radiation in deep water. The latter subgenera are thought to have arisen from the larger subgenera by neoteny. The thyasirids, unlike the deep-sea protobranch and septibranch bivalves, are predominantly inhabitants of slope depths. Very few are truly abyssal. Many have very wide depth distributions extending from shelf to abyssal depths. This, together with the production of planktotrophic larvae, has ensured that most thyasirid species, unlike other deep-sea bivalves, are very widely distributed. Thus species extend into Arctic waters, including the Norwegian Basin and into the Pacific and are truly cosmopolitan.

Surface-enhanced Raman scattering (SERS) and localized surface plasmon resonance sensing (LSPR) have been applied for a detailed analysis of lipid bilayers at the surface of gold nanorods. The spatial dependence of surface enhancement and the optical effects of the lipid phase transition confirm the presence of a bilayer membrane structure. Deuterated lipids exchanged rapidly between the nanorod surface and lipid vesicles in solution, suggesting a loosely bound, natural membrane structure. However, at a low solution concentration of lipid vesicles, the lipids on the gold nanorod surface convert to a nonbilayer structure, which could impact biological applications of these nanomaterials.

Changes in sea ice thickness and extent have corresponded with substantial changes in net primary production (NPP) in the Arctic Ocean. In recent years, observations of massive phytoplankton blooms under sea ice have upended the previous paradigm that Arctic NPP was driven largely by growth in the marginal ice zone and open water periods. Here, a new 1‐D biogeochemical model capable of simulating ice algal and phytoplankton dynamics both under the ice and in open waters is applied in the northern Chukchi Sea for the years 1988–2018. Over this period, substantial under‐ice (UI) blooms were produced in all but four years and were the primary drivers of interannual variation in total NPP. While NPP in the UI period was highly variable interannually due to fluctuations in ice thickness and the length of the UI period, UI NPP accounted for nearly half of total NPP between 1988 and 2018. Further, years with high UI NPP had reduced annual zooplankton grazing, indicating an intensification in the mismatch between phytoplankton and zooplankton populations and possibly altering the partitioning of food between benthic and pelagic ecosystems. These results demonstrate that the often‐overlooked ice covered period can be highly productive in the Arctic Ocean, and that the northern Chukchi Sea has been amenable to UIB formation since at least 1988.

Plasmon propagation in thin plasmonic waveguides is strongly damped, making it difficult to study with diffraction-limited optics. Here we directly characterize plasmon propagation in gold nanobelts with incoherent light. The data indicate a short average propagation length of 0.94 μm but also reveal a weakly excited antisymmetric mode that has a propagation length greater than 10 μm with strong confinement of 2400 nm(2). These results demonstrate that high confinement and long propagation length can be achieved with thin plasmonic structures.

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