Fabrication of Poly(L‐lactide)‐block‐Poly(ethylene glycol)‐block‐Poly(L‐lactide) Triblock Copolymer Thin Films with Nanochannels: An AFM Study

This paper aims to report the fabrication of biodegradable thin films with micro‐domains of cylindrical nanochannels through the solvent‐induced microphase separation of poly(L ‐lactide)‐block‐poly(ethylene glycol)‐block‐poly(L ‐lactide) (PLA‐b‐PEG‐b‐PLA) triblock copolymers with different block ratios. In our experimental scope, an increase in each of the block lengths of the PLA and PEG blocks led to both a variation in the average number density (146 to 32 per 100 µm²) and the size of the micro‐domains (140 to 427 nm). Analyses by atomic force microscopy (AFM) and fluorescence microscopy indicated that the hydrophilic PEG nanochannels were dispersed in the PLA matrix of the PLA‐b‐PEG‐b‐PLA films. We demonstrated that the micro‐domain morphology could be controlled not only by the block length of PEG, but also by the solvent evaporation conditions.

     

Cyclostationary spectral analysis for the measurement and prediction of wind turbine swishing noise

This paper introduces cyclostationary spectral analysis as a new approach to analyzing and predicting the aerodynamic noise generated by wind turbines. This method is able to reveal new insights into the periodic character of the noise signal and is therefore ideally suited to the study of wind turbine noise. A new formulation is presented for the time variation of the noise spectrum due to wind turbines thereby providing insight into the character of the periodic variation in noise referred to as ‘swishing’. The character and mechanism of swishing noise is analyzed in detail.     

Multiprotein Dynamic Combinatorial Chemistry: A Strategy for the Simultaneous Discovery of Subfamily‐Selective Inhibitors for Nucleic Acid Demethylases FTO and ALKBH3

Dynamic combinatorial chemistry (DCC) is a powerful supramolecular approach for discovering ligands for biomolecules. To date, most, if not all, biologically templated DCC systems employ only a single biomolecule to direct the self‐assembly process. To expand the scope of DCC, herein, a novel multiprotein DCC strategy has been developed that combines the discriminatory power of a zwitterionic “thermal tag” with the sensitivity of differential scanning fluorimetry. This strategy is highly sensitive and could differentiate the binding of ligands to structurally similar subfamily members. Through this strategy, it was possible to simultaneously identify subfamily‐selective probes against two clinically important epigenetic enzymes: FTO ( 7 ; IC₅₀=2.6 μm ) and ALKBH3 ( 8 ; IC₅₀=3.7 μm ). To date, this is the first report of a subfamily‐selective ALKBH3 inhibitor. The developed strategy could, in principle, be adapted to a broad range of proteins; thus it is of broad scientific interest.     

Analysis of saxitoxin in urine by continuous-flow fast-atom bombardment mass spectrometry.

An improved method of saxitoxin analysis in urine using continuous-flow fast-atom bombardment mass spectrometry was developed. Parameters studied were matrix composition, matrix flow, temperature of probe tip, probe-tip design and sample extraction. Optimal detection was obtained using the following matrix composition: 5% glycerol, 0.5% acetic acid, 0.025% sodium dodecylsulfate, 0.1% polyethylene glycol (PEG) 400 and 0.5% PEG 300; probe-tip temperature: (approximately 55 degrees C); flow rate: 5 or 8 microL per min.; probe tip: Olson-Hogge design. The STX standard was detected at 200 pg with signal-to-noise ratio of 11. The percent recovery of saxitoxin from human urine after clean-up on a weak cation exchange column was 75%.     

Optical investigations of polycrystalline Mg1−xB2 near metal-insulator transition

We measured reflectivity spectra of polycrystalline Mg_1−xB₂ samples, which show a metal-insulator transition with x. After performing the Kramers-Kronig analysis, the obtained optical conductivity spectra σ(ω) of MgB₂ show a narrow Drude peak in the far-infrared region and a broad peak in the mid-infrared region. As x increases, the spectral weight of the Drude peak is strongly suppressed and that of the broad peak becomes enhanced a little. The existence of the broad mid-infrared peak in the insulating sample suggests that this peak might not be related to the free carriers in MgB₂. In the far-infrared region, we also observe that the low energy dielectric constant of Mg_1−xB₂ diverges near the metal-insulator phase boundary (i.e. x=0.08). This result implies the possibility of a phase separation and a percolative metal-insulator transition in Mg_1−xB₂.     

Rhodium-catalyzed double carbonylation of diiodomethane in the presence of triethylorthoformate

Catalytic double carbonylation of diiodomethane in triethylorthoformate in the presence of a homogeneous rhodium complex gives diethylmalonate in a fairly good yield.     

Mössbauer study of magnetic ordering in57Co-doped Eu2CuO4 and Gd2CuO4

Zeeman splitting of Mossbauer spectra of⁵⁷Co doped into Eu₂CuO₄ and Gd₂CuO₄ indicates magnetic ordering of Cu moments for temperatures below about 150 K in Eu₂CuO₄ and below about 200 K in Gd₂CuO₄. Supported by NASA Grant NAG 3-847