Inside Cover: Self‐Template‐Directed Formation of Coordination‐Polymer Hexagonal Tubes and Rings,and their Calcination to ZnO Rings (Angew. Chem. Int. Ed. 8/2009)

Hexagonal tubes and rings with unusual shapes were generated through a unique self‐template‐directed growth mechanism. As described by M. Oh and co‐workers in the Communication on page 1459 ff., initially formed solid coordination polymer particles (CPPs) act as templates for the growth of the final hexagonal tubes and rings. Simple calcination of these unusually shaped CPPs results in the spontaneous formation of ZnO particles while the unique shape is maintained.

     

Mesoporous TiO2 nano networks: Anode for high power lithium battery applications

Anatase phase mesoporous TiO₂ with I41/amd space group was synthesized via the urea assisted hydrothermal method. The existence of mono phasic TiO₂ sub-microspheres of uniform particle size (ca. 400 nm) encompassing an average crystallite size of 14 nm was demonstrated using the XRD, FE-SEM and TEM analysis. Surface area of ca. 116.49 m²/g along with a pore size of 7 nm was calculated using the BET and adsorption isotherm measurements which authenticated the mesoporous nature of the synthesized material. Suitable calcination temperature for the better electrochemical property was established via the optimization process. Accordingly, the mesoporous TiO₂ calcined at 400 °C displayed improved cycleability with excellent rate capability ever reported, even at 20 C-rate of discharge. The reason for the superior rate capability is corroborated to the highly mesoporous nature of the TiO₂ sub-microspheres that has imparted desirable surface area apposite for enhanced ionic and electronic diffusion.     

Capacitance response of double-walled carbon nanotubes depending on surface modification

The capacitive behaviors of high-purity double-walled carbon nanotubes (DWNTs) were investigated before and after oxidation using nitric acid (HNO₃). The electrodes prepared from the HNO₃-oxidized DWNTs have exhibited higher capacitances than the pristine nanotube electrode in both aqueous and non-aqueous systems, despite the deterioration of their specific surface area after HNO₃ oxidation. The superiority of the HNO₃-oxidized DWNTs in capacitance properties is caused by the variations of surface wettability and the interstitial pore structure of nanotube bundles, which result from the introduction of polar oxygen functional groups onto the nanotube surface by HNO₃ oxidation.     

Cover Picture: Toroidal Micelles of Uniform Size from Diblock Copolymers (Angew. Chem. Int. Ed. 25/2009)

Pure toroidal micelles of highly uniform shape and size are presented by T. Chang et al. in their Communication on page 4594 ff. The donut‐shaped micelles are prepared by spontaneous self‐assembly of a polyisoprene‐block‐poly(2‐vinylpyridine) copolymer, and are stable enough to act as a template for the growth of gold nanoparticles along the ring surface.

     

A Micellar Complex of a Conjugated Polyelectrolyte for Efficient FRET to Dye‐Labeled DNA

A polymer–surfactant micellar complex has been studied as a fluorescence resonance energy transfer (FRET) donor to fluorescein‐labeled DNA (ssDNA‐Fl). In water, the molar absorptivity and fluorescence quantum efficiency of cationic poly(fluorene‐co‐phenylene) (c‐PFP) are substantially increased in the presence of non‐ionic surfactants. A TEM microscopic study shows the formation of a nanowire micellar complex of c‐PFP and the surfactants. About a 400% enhancement of the FRET signal is measured in c‐PFP/ssDNA‐Fl with Brij 30, relative to that without surfactants. The signal amplification is successfully modulated using different types of non‐ionic surfactants which perturb the complexation, fine‐structure of the complex (i.e., donor‐acceptor separation), and the resulting energy transfer process.

     

Radiocatalytic H2 production with gamma-irradiation and TiO2 catalysts

The radioactive concentrations of radionuclides were measured in the soil and groundwater below the 12 GeV proton beam-line tunnel at KEK. Various long-lived radionuclides, (⁷Be, ²²Na, ⁴⁶Sc, ⁵⁴Mn, ⁶⁰Co, ¹³⁴Cs, ¹⁵²Eu and ¹⁵⁴Eu) were observed in the soil samples by -ray spectra measurements, and ³H was also detected by liquid scintillation counting. On the other hand, ³H, ²²Na and ⁵⁴Mn, which were leached from the soil were measured in the groundwater below the EP2 beam line. ³H and ²²Na were also found in slight amounts in groundwater collected in a well dug beside the East Counter Hall. From a comparison with the radioactive concentration in soil and groundwater, the order of the leaching percentages were ³H>²²Na>⁵⁴Mn. This tendency was in agreement with an experimental result of the RI laboratory.     

Transformation of arctiin to estrogenic and antiestrogenic substances by human intestinal bacteria

After anaerobic incubation of arctiin (1) from the seeds of Arctium lappa with a human fecal suspension, six metabolites were formed, and their structures were identified as (-)-arctigenin (2), (2R,3R)-2-(3',4'-dihydroxybenzyl)-3-(3",4"-dimethoxybenzyl)butyrolactone (3), (2R,3R)-2-(3'-hydroxybenzyl)-3-(3",4"-dimethoxybenzyl)butyrolactone (4), (2R,3R)-2-(3'-hydroxybenzyl)-3-(3"-hydroxy-4"-methoxybenzyl)butyrolactone (5), (2R,3R)-2-(3'-hydroxybenzyl)-3-(3",4"-dihydroxybenzyl)butyrolactone (6), and (-)-enterolactone (7) by various spectroscopic means including two dimensional (2D)-NMR, mass spectrometry, and circular dichroism. A possible metabolic pathway was proposed on the basis of their structures and the time course of the transformation. Enterolactones obtained from the biotransformation of arctiin and secoisolariciresinol diglucoside (SDG, from the seeds of Linum usitatissium) by human intestinal bacteria were proved to be enantiomers, with the (-)-(2R,3R) and (+)-(2S,3S) configurations, respectively. Compound 6 showed the most potent proliferative effect on the growth of MCF-7 human breast cancer cells in culture among 1 and six metabolites, while it showed inhibitory activity on estradiol-mediated proliferation of MCF-7 cells at a concentration of 10 microM. These results indicate that the transformation of 1 by intestinal flora might be essential for the manifestation of the estrogenic and antiestrogenic activity of 1.     

Direct determination of estriol 3- and 16-glucuronides in pregnancy urine by column-switching liquid chromatography with electrospray tandem mass spectrometry

Using column-switching liquid chromatography/tandem mass spectrometry (LC-MS/MS), we developed an improved analytical method of urinary estriol glucuronides. This new method is derived predominantly from maternal and fetal precursors in pregnancy. We used in the following procedure: first, we filtered urine samples with a membrane filter. Next, we directly injected the 50 microL aliquot of urine samples onto a pre-column. Then, after activating the column-switching valve, we backflushed the loaded samples onto the C(18) analytical column. Urine samples can be assayed within 20 min without any sample preparation steps. We monitored separated estriol glucuronides by negative electrospray ionization (ESI) and selected-reaction monitoring (SRM). The calibration range of estriol-3-glucuronide (E3-3G) and estriol-16-glucuronide (E3-16G) was 0.1-20 microg/mL and the linearity of the method was 0.9984 for E3-3G and 0.9987 for E3-16G. The limits of detection at a signal-to-noise (S/N) ratio of 3 were 10 ng/mL (E3-3G) and 5 ng/mL (E3-16G). The analytical recovery was over 85% and, in general, inter-day and intra-day variability for precision and accuracy were less than 10%. When applied to a pregnancy urine sample to biomedical monitoring of the function of the maternal/fetal unit, the proposed method allowed rapid and sensitive screening for the detection of E3-3G and E3-16G.