Cytotoxic 5‐Hydroxyindole Alkaloids from the Marine Sponge Scalarispongia sp.

Three new 5‐hydroxyindole alkaloids ( 1 , 2 , 3 ) along with seven known analogs ( 4 , 5 , 6 , 7 , 8 , 9 , 10 ) were isolated from a Dokdo marine sponge Scalarispongia sp. The elucidation of the structures of the new compounds by spectroscopic analyses indicated that these compounds were an indole glyoxylate ( 1 ), a mono‐indole analog of hyrtinadine A ( 2 ), and a symmetrical bis‐indole with pyridine linker ( 3 ). The comparison of IC₅₀ values for obtained compounds against a human leukemia cell line revealed that the bis‐indole structure is a requirement for cytotoxicity.     

Spatially‐resolved and polarized Raman scattering from a single Si nanowire

We report spatially‐resolved and polarized Raman scattering results from a single Si nanowire (NW). Transmission electron microscope images show that the surface morphology of the Si NW varies from smooth to rough along the long axis. As the NW grows, the smooth surface becomes rough because of Au diffusion to the surface, resulting in the formation of facets and stacking faults. Spatially‐resolved Raman spectra along the NW long axis reveal variations in tensile strain related to the morphological changes in NW surface. The tensile strain in the top segment of the NW with a smooth surface is greater than that in the bottom segment with a rough surface. Despite the formation of facets and stacking faults, polarized Raman scattering results both from the top and bottom segments of the NW are consistent with the Raman polarization selection rules expected for a cubic crystal. Copyright © 2015 John Wiley & Sons, Ltd.     

Nanocatalosomes as Plasmonic Bilayer Shells with Interlayer Catalytic Nanospaces for Solar‐Light‐Induced Reactions

Interest and challenges remain in designing and synthesizing catalysts with nature‐like complexity at few‐nm scale to harness unprecedented functionalities by using sustainable solar light. We introduce “nanocatalosomes”—a bio‐inspired bilayer‐vesicular design of nanoreactor with metallic bilayer shell‐in‐shell structure, having numerous controllable confined cavities within few‐nm interlayer space, customizable with different noble metals. The intershell‐confined plasmonically coupled hot‐nanospaces within the few‐nm cavities play a pivotal role in harnessing catalytic effects for various organic transformations, as demonstrated by “acceptorless dehydrogenation”, “Suzuki–Miyaura cross‐coupling” and “alkynyl annulation” affording clean conversions and turnover frequencies (TOFs) at least one order of magnitude higher than state‐of‐the‐art Au‐nanorod‐based plasmonic catalysts. This work paves the way towards next‐generation nanoreactors for chemical transformations with solar energy.     

Pion condensation in symmetric nuclear matter

The problem of pion condensation in isospin symmetric nuclear matter is investigated in the framework of the σ-model with a residual nucleon-nucleon interaction (g′σ₁ · σ₂τ₁ · τ₂δ(x)) and Δ-isobars. The equation of state for the pion condensed phase is calculated and applied to a low-energy heavy-ion collision in the TDHF approximation. The effective particle-hole interaction and the response to spin-isospin excitation are used to determine the magnitude of the Landau-Migdal parameter g′. For a reasonable range of g′(0.5 < g′ ≦ in units of g²/4m²_N = 410 MeV · fm³) pion condensation occurs at densities above normal nuclear matter density and leads to an equation of state with no stable density isomer.     

Chiral symmetry and many-body forces in nuclei

It is demonstrated that when quantum correlations are added, chiral Lagrangians need not generate strong many-body forces as they do in tree approximation. We suggest that a physically reasonable procedure is to adjust the σ-model parameters so as not to conflict with the current status of nuclear theory. As a consequence, the equilibrium density of abnormal states could be pushed up further, and the binding energy be considerably reduced.     

Evidence for 2D precursors and interdiffusion in the evolution of self-assembled CdSe quantum dots on ZnSe

The evolution of self-assembled CdSe quantum dots deposited on (and subsequently capped by) ZnSe was investigated on a series of samples grown by molecular beam epitaxy, with CdSe coverages from 0.5 to 2.6 monolayers. The samples were investigated by cross-sectional scanning transmission electron microscopy, as well as macro- and microphotoluminescence. The results clearly indicated a coexistence of 2D ZnCdSe platelets and 3D islands, showing clearly that the platelets act as precursors for the formation of the 3D islands.     

Unconventional photoluminescence effect of SrTiO3 thin film under UV-illumination

We find that PL intensity I(t) of SrTiO₃ thin film measured under UHV condition increases with UV-laser illumination over long time scale of ∼ 2 h. The intensity increase takes place at lower sample temperature as well, 200, 100 K, and 20 K. When O₂ and N₂ gas are introduced into the sample chamber the PL intensity decreases with the UV-illumination time, opposite to the UHV-case. We consider a quantitative thermal energy flow model of the laser-power and heat absorption by the sample, but find that temperature change of the sample is not large enough to account for the time dependent I(t). We propose photo-catalysis effect on STO surface as possible scenario of the PL intensity change.     

Structural determination of cerebrosides isolated from Asterias amurensis starfish eggs using high-energy collision-induced dissociation of sodium-adducted molecules

Six cerebrosides were isolated from the eggs of the starfish Asterias amurensis using solvent extraction, silica gel column chromatography, and reversed‐phase high‐performance liquid chromatography. This study demonstrated that the structures of cerebrosides could be completely characterized, based on their sodium‐adducted molecules, using fast atom bombardment (FAB) tandem mass spectrometry. The high‐energy collision‐induced dissociation of the sodium‐adducted molecule, [M + Na]⁺, of each cerebroside molecular species generated abundant ions, providing information on the compositions of the 2‐hydroxy fatty acids and long‐chain sphingoid bases, as well as the sugar moiety polar head group. Each homologous ion series along the fatty acid and aliphatic chain of the sphingoid base was useful for locating the double‐bond positions of both chains and the methyl branching position of the long‐chain base. The N‐fatty acyl portions were primarily long‐chain saturated or monoenoic acids (C16 to C24) with an α‐hydroxy group. The sphingoid long‐chain base portions were aliphatic chains (C18 or C22) with two or three degrees of unsaturation and with or without methyl branching. Copyright © 2011 John Wiley & Sons, Ltd.     

Kaempferol and kaempferol rhamnosides with depigmenting and anti-inflammatory properties

The objective of this study was to examine the biological activity of kaempferol and its rhamnosides. We isolated kaempferol (1), a-rhamnoisorobin (2), afzelin (3), and kaempferitrin (4) as pure compounds by far-infrared (FIR) irradiation of kenaf (Hibiscus cannabinus L.) leaves. The depigmenting and anti-inflammatory activity of the compounds was evaluated by analyzing their structure-activity relationships. The order of the inhibitory activity with regard to depigmentation and nitric oxide (NO) production was kaempferol (1) > a-rhamnoisorobin (2) > afzelin (3) > kaempferitrin (4). However, a-rhamnoisorobin (2) was more potent than kaempferol (1) in NF-kB-mediated luciferase assays. From these results, we conclude that the 3-hydroxyl group of kaempferol is an important pharmacophore and that additional rhamnose moieties affect the biological activity negatively.