Thermal Degradation and Flame Resistivity of Tetrabrominated Epoxy Resin

The thermal degradation mechanism of tetrabrominated epoxy resin was investigated in order to explain its flame retardant mechanism. From the results obtained it was concluded that the flame retardant mechanisms are 1) a lowering of temperature through degradation and 2) the formation of hydrogen bromide and its role in catalysis in the condensation reaction of the resin.

These mechanisms were investigated by the pyrolysis behavior of the resin by gas chromatography, thermal gravimetric analysis, and differential thermal analysis studies.     

Multifunctional Core–Shell Silica Nanoparticles for Highly Sensitive 19F Magnetic Resonance Imaging

¹⁹F magnetic resonance imaging (¹⁹F MRI) is useful for monitoring particular signals from biological samples, cells, and target tissues, because background signals are missing in animal bodies. Therefore, highly sensitive ¹⁹F MRI contrast agents are in great demand for their practical applications. However, we have faced the following challenges: 1) increasing the number of fluorine atoms decreases the solubility of the molecular probes, and 2) the restriction of the molecular mobility attenuates the ¹⁹F MRI signals. Herein, we developed novel multifunctional core–shell nanoparticles to solve these issues. They are composed of a core micelle filled with liquid perfluorocarbon and a robust silica shell. These core–shell nanoparticles have superior properties such as high sensitivity, modifiability of the surface, biocompatibility, and sufficient in vivo stability. By the adequate surface modifications, gene expression in living cells and tumor tissue in living mice were successfully detected by ¹⁹F MRI.     

Bacterial wetting agents working in colonization of bacteria on surface environments

Bacteria are very small and highly susceptible to the effects of intermolecular forces. Especially, bacteria living on solid-air interfaces are under a strong influence from the surface tension of water. During studies of bacteria which prefer to live on surfaces, we noted that some species of bacteria (e.g. Serratia marcescens) secrete large amounts of wetting agents (e.g. serrawettins). Therefore, we isolated mutants defective in the production of wetting agents and examined the physiological functions of these wetting agents by comparing the behavior of wild types and mutants on surface environments. In terms of accessibility to the water-repelling surfaces and spreading growth on solid media. mutants demonstrated inferior abilities in comparison with wild types. Thus, the ability of S. marcescens to form a giant fractal colony through nutrient-diffusion-limited growth processes was shown to be defective in the serrawettinless mutants. In the locomotion of flagellated bacteria on surfaces, the bacteria seem to overcome various restrictive intermolecular forces. In contrast to swimming in a liquid, a single bacterium alone was unable to translocate on a surface. By video-microscopic analyses, the cooperative multicellular behavior of bacteria was clearly demonstrated. The remarkable effects of wetting agents on such microbial swarming behavior on surfaces were also disclosed.     

Effect of crystallization and liquid–liquid phase separation on phase‐separation kinetics in poly(ethylene‐co‐vinyl alcohol)/glycerol solution

Liquid–liquid thermally induced phase separation of the polymer‐diluent system of poly(ethylene‐co‐vinyl alcohol) (EVOH)‐glycerol was examined under light scattering. For EVOH with an ethylene content of 38 mol % (EVOH38), maxima of the scattered light intensity were observed that indicated that phase separation occurred by the spinodal decomposition (SD). The growth of the structures formed by the general liquid–liquid phase separation obeyed a power‐law scaling relationship in SD. For EVOH with an ethylene content of 32 mol % (EVOH32), the liquid–liquid phase separation resulted from the polymer crystallization. In this case, the structure growth showed the characteristic behavior in which the crystalline particles were initially formed, and then the droplets formed by the liquid–liquid phase separation induced by the crystallization grew rapidly. Furthermore, the growth of the droplet by the phase separation was followed by an optical microscope measurement at a constant cooling rate. The phase‐separated structure formed after the crystallization can grow faster than that formed by the normal liquid–liquid phase separation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 194–201, 2003     

Transamidation reactions in the formation of macrocyclic lactams. A total synthesis of celacinnine

The macrocyclic spermidine alkaloid, celacinnine, has been synthesized by methods involving successive ring expansion reactions. One route starts with 4-phenyl-2-azetidinone; another, with piperidazine.     

Simulation and Experimental Study of Wavefront Measurement Accuracy of the Pencil-Beam Method

Ultra-bright and high-coherence X-rays are now being used in synchrotron radiation facilities and X-ray free electron laser facilities. X-ray focusing techniques are essential to take full advantage of these excellent X-ray light sources. To meet the strong demand, high-quality X-ray focusing optics have been developed owing to the advancement of ultraprecision machining and measurement. State-of-the-art refractive lenses [1 C.G. Schroer, Applied Physics Letters 87, 124103 (2005).[Crossref], [Web of Science ®] , [Google Scholar]], zone plates [2 T. Chen, Optics Express 19, 19919 (2011).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]], and Laue lenses [3 H. Yan, Optics Express 19, 15069 (2011).[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]] can be used to achieve X-ray focusing to a spot a few tens of nanometers.