The cover picture shows an epifuorescence-microscopic view (excitation: 360 nm, emission: 460 nm) of a microalgal epiphytic community growing on a field-collected branch of the red seaweed Gracilaria chilensis. Host cells and membranes are often damaged by penetrating epiphytes such as Acrochaetium sp. (shown as up to 2.5 mm-long filaments in the picture). In their article on p. 457 ff, G. Pohnert et al. provide evidence that the hydroxylated eicosanoids shown in yellow are generated through two distinct biosynthetic pathways after wounding of G. chilensis. These compounds activate resistance against spore settlement of A. operculata. A related article on aldehyde biosynthesis in the marine diatom Thalassiosira rotula by A. Fontana et al. can be found on p. 450 f.
-416
A Central Strategy for Converting Natural Products into Fluorescent ProbesA centralized method for studying natural product chemical biology begins by designating a single fluorescent dye as a core reporter and develops through the facile conversion to a diverse panel of fluorescently labeled natural products. Comparative analyses are developed by using LED fluorescence microscopy. Application of this method is established by profiling the cellular uptake and localization of selected members of the anthracycline, acetogenin, depsipeptide, nonribosomal peptide, polyether, and polyketide families of natural products.
03/2006ChemBioChem is a European journal of chemical biology; it is co-owned by a group of European scientific societies and published by WILEY-VCH. Contributions in ChemBioChem cover chemical biology and biological chemistry, medicinal chemistry, bioinorganic and bioorganic chemistry, biochemistry, molecular and structural biology, that is, research of the overlapping areas between biology and chemistry.
Published data on the synthesis of rhodium and palla-Published data on the synthesis of rhodium and palladium complexes with optically active P,N-bidentate ligands and dium complexes with optically active P,N-bidentate ligands and their applications in homogeneous asymmetric catalysis are their applications in homogeneous asymmetric catalysis are summarised and discussed. The effect of the nature of the P,N-summarised and discussed. The effect of the nature of the P,Nbidentate compounds on the structure of the metal complexes and bidentate compounds on the structure of the metal complexes and on enantioselectivity in catalysis is examined. Allylic substitution, on enantioselectivity in catalysis is examined. Allylic substitution, cross-coupling, hydroboration and hydrosilylation catalysed by cross-coupling, hydroboration and hydrosilylation catalysed by Rh or Pd complexes with optically active P,N-bidentate ligands Rh or Pd complexes with optically active P,N-bidentate ligands are considered. The prospects for the development of this field of are considered. The prospects for the development of this field of chemistry are demonstrated. The bibliography includes 186 refer-chemistry are demonstrated. The bibliography includes 186 references ences. .
New chiral P,N-hybrid aryl phosphites have been obtained by one-step phosphorylation of amino and imino alcohols. Complexation of the new ligands with [Rh(CO) 2 Cl] 2 , [Pd(COD)Cl 2 ] and [Pd(allyl)Cl] 2 was found to give chelate complexes [Rh(CO)Cl(η 2 -P ʝ N)], [PdCl 2 (η 2 -P ʝ N)] and [Pd-(allyl)(η 2 -P ʝ N)] + Cl − , respectively. With these new P,N-ligands, up to 82% ee enantioselectivity was achieved in the [a] The new P,N-bidentate aryl phosphites were synthesized by one-step phosphorylation of the corresponding amino and imino alcohols with bis(2,6-dimethylphenyl) chlorophosphite.They divide into two groups: ligands 3aϪ3f, possessing sp 3 -hybridized nitrogen atoms, and ligands 3gϪ3m, which have sp 2 -hybridized nitrogen atoms. All the compounds 3aϪm are soluble in conventional organic solvents and stable under dry conditions for several months. On treatment with [Rh(CO) 2 Cl] 2 , their neutral carbonyl(chloro)Rh I complexes were obtained.The ν(CO) and 1 J P,Rh parameters in their IR and 31 P NMR spectra act as sensitive indicators, which characterise the mode of complexation of the P,N-ligands and allow the π-acceptor ability of the phosphorus centre and the degree of electronic non-symmetry of the ligands to be estimated. [13Ϫ15] In general, ligands 3aϪ3m give chelate complexes. Thus, the
AlGaN/GaN/Si metal-insulator-semiconductor heterostructure field-effect transistors (MISHFETs) with SiN and Al 2 O 3 gate insulators are characterized by static and high-frequency measurements, and their performance is compared with nonpassivated and SiN-passivated heterostructure field-effect transistors (HFETs). The saturation drain current increased from ∼500 mA mm −1 for the HFETs to ∼770 mA mm −1 for the MISHFETs. The peak extrinsic transconductance of the MISHFETs (147 mS mm −1 for 8 nm SiN and 220 mS mm −1 for 4 nm Al 2 O 3 ) is higher than expected due to the increased gate-to-channel separation. Similarly, small signal microwave characterization yielded an increase in the current gain cut-off frequency (from 3.2 to 7.2 GHz) and the maximum frequency of oscillation (from 12.3 to 20.4 GHz) for the MISHFETs with 2 μm gate length compared to the HFET counterparts. Finally, the density of trap states, evaluated from the frequency-dependent conductance measurements, was ∼ =3 × 10 12 cm −2 eV −1 for the HFETs but only ∼ =1.8 × 10 12 cm −2 eV −1 for the MISHFETs. All of these demonstrate the capability of AlGaN/GaN MISHFETs of preparing high-performance and cost-effective devices for high-power microwave applications on a Si substrate.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.