The results of dynamic mechanical analysis (DMA) revealed that there were double tan δ peaks in the poly(vinyl alcohol)(PVA)/silica nanocomposite samples at low frequencies. The two relaxations attribute to glass transition for PVA matrix and motions of segments for PVA chains confined by the surface of silica nanoparticles, respectively. The thickness of the interfacial immobilized layer was calculated, and schematic models were founded, which can well interpret the results. The changes of the two relaxations with various silica contents at different frequencies are discussed. It is considered that most of the interfacial PVA chains probably span the two layers. The peak position of the first relaxation moves to high temperature with the increase of frequency for strain lag of the sample whereas the second one shifts to low temperature for the "drag effect" between the intrinsic and interfacial segments of the spanned PVA chains.

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Isopenicins A−C (1−3), three novel meroterpenoids possessing two types of unprecedented terpenoidpolyketide hybrid skeletons, were isolated from the cultures of Penicillium sp. sh18. Their structures were determined through synergetic use of extensive spectroscopic analysis, quantum-chemical calculation with ANN−PRA analysis, and X-ray crystallographic analysis. Additionally, the inhibitory activities of these compounds on the Wnt/β-catenin signaling pathway were evaluated, and 1 was identified as a potent inhibitor of the Wnt signaling pathway.

In the present paper, the diffusion barrier properties of amorphous and nanocrystalline (NC) Ta films, and the interface microstructure of Ta/Cu were investigated as a function of annealing temperature. X-ray diffraction, scanning electron microscopy, cross-sectional transmission electron microscopy, and energy-dispersive spectrometer line scans were employed to study the microstructure evolution and diffusion behavior. It was found that an amorphous layer with a thickness of ∼5 nm formed at the interface of NC Ta/Cu at 450 °C annealing, while the interface of amorphous-Ta/Cu was still abrupt. Moreover, amorphous-Ta film acts as an effective diffusion barrier up to temperatures of 650 °C, which is higher than that for NC-Ta film. The fast diffusion along grain boundaries inside NC-Ta films is suggested to be responsible for the main failure of NC-Ta film.

SummaryUnusually among bacteria, actinobacteria possess myo-inositol 1-phosphate synthase (mIPS). In the developmentally complex Streptomyces coelicolor, the mIPS-encoding gene (inoA) is cotranscribed with a putative regulatory gene (inoR). The inoRA transcript was more abundant in an inoR in-frame deletion mutant, and InoR formed different complexes in vitro with an extensive region around the inoRA promoter. Binding was relieved by adding glucose 6-phosphate. Thus, InoR is a metabolite-sensitive autorepressor that influences inoA expression, and hence the level of inositol, by controlling transcription from P inoRA. Disruption of inoA resulted in inositol-dependent growth and development, with full phenotypic correction at 0.1 mM inositol: at lower inositol concentrations differentiation was arrested at intermediate stages. This pattern may partly reflect increased demand for membrane phospholipids during sporulation septation. A corresponding sharp upregulation of inoRA transcription coincident with sporulation was dependent on a developmental regulator, WhiI. A truncated form of WhiI could bind two sites downstream of P inoRA, and one of the WhiI-binding sites overlapped the InoRbinding site. The combined action of a metabolic regulator and a developmental regulator at the simple PinoRA promoter is a previously undescribed strategy for the differential provision of developmentally appropriate levels of a substance required during the formation of spore chains.

The microstructure of samples before and after a high current density electropulsing treatment was characterized by using high-resolution transmission electron microscopy. It has been found that in the coarse-grained Cu–Zn alloy subjected to the electropulsing treatment, two nanophases were formed, α–Cu(Zn) and β′–(CuZn), the average grain size of which is about 11 nm. A possible mechanism for the formation of nanophases was proposed. The experimental results indicated that electropulsing, as an instantaneous high-energy input, plays an important role in the nonequilibrium microstructural changes in materials and serves as a potential processing approach to synthesize nanostructured materials.

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Nine dimeric acylphloroglucinols, including the new hyperjaponicols A-D (1-4), were isolated from the whole plant of Hypericum japonicum. The new structures were determined by the interpretation of NMR and MS data, and the relative configuration of the known compound, sarothralen C (5), was reassigned via NMR spectroscopic analysis and single-crystal X-ray diffraction data. The inhibitory activities of the isolates against four bacterial strains were evaluated, and compounds 1-4, 6, and 7 exhibited significant antibacterial activity with MIC values of 0.8-3.4 μM. In addition, compound 3 showed moderate lipase inhibitory activity (IC 8.3 μM).