Performance of FCCI barrier foils for U-Zr-X metallic fuel

Diffusion couple tests of U-Zr or U-Zr-Ce alloys vs. ferritic martensitic steels such as HT9 or T91 were carried out in order to evaluate the performance of the diffusion barrier candidates. Elemental metal foils of Zr, Nb, Ti, Mo, Ta, V and Cr were very effective in inhibiting interdiffusion between these fuels and steels. Eutectic melting between the fuels and steels was not observed in any of the diffusion couples using these diffusion barrier foils at annealing temperatures up to 800 °C. Among the metallic foils evaluated in this study, V and Cr exhibited the most promising performances as a diffusion barrier material for eliminating the fuel cladding chemical interaction problem. However, Zr, Nb and Ti showed an active interaction with the fuel mainly due to the large U solubility.     

Cytotoxic Petrosiacetylenes from the Marine Sponge Petrosia sp.

A novel petrosiacetylene analog (petrosiacetylene E) has been isolated from the Korean marine sponge Petrosia sp., along with petrosiacetylene A, B and C. Their structures were elucidated on the basis of spectroscopic methods and the stereochemistry of the new compound was determined by using the modified Mosher’s method. Petrosiacetylene E showed higher cytotoxicity against five human cancer cell lines than petrosiacetylene A and B, presumably due to the additional hydroxy group located at C-16.     

One-step large-scale synthesis of micrometer-sized silver nanosheets by a template-free electrochemical method

We have synthesized micrometer-sized Ag nanosheets via a facile, one-step, template-free electrochemical deposition in an ultra-dilute silver nitrate aqueous electrolyte. The nanosheet growth was revealed to occur in three stages: (1) formation of polygonal Ag nuclei on a substrate, (2) growth of {112}-faceted nanowire from the nuclei, and (3) anisotropic growth of (111)-planar nanosheets, approximately 20 to 50 nm in thickness and 10 μm in width, in the <112>−direction. The vertical growth of the facet nanowire was induced by the strong interface anisotropy between the deposit and electrolyte due to the ultra-dilute concentration of electrolyte and high reduction potential. The thickness of Ag nanosheets was controllable by the adjustment of the reduction/oxidation potential and frequency of the reverse-pulse potentiodynamic mode.     

A Versatile Synthetic Platform Based on Bicyclo[4.1.0]heptenes

Bicyclo[4.1.0]heptenes, which are readily accessible molecules via the transition metal-catalyzed cycloisomerization of 1,6-enynes, and have served as useful building blocks in organic synthesis. These molecules can undergo a variety of ring-opening reactions given that the release of the cyclopropyl ring strain (27.5 kcal/mol) may serve as a thermodynamic driving force for reactions, and the double bond within the skeleton can afford the kinetic opportunity to initiate the ring-opening via a coordination to a metal species. Even though the chemistry of the cyclopropyl group has been widely explored in organic chemistry, less attention has been paid to the chemistry of bicyclo[4.1.0]heptenes. However, during the past 5 years, we have been engaged in the exploration of the chemistry of bicyclo[4.1.0]heptenes. This review describes the chemistry developed in our laboratory. Depending upon the position, number, and identity of the substituent(s), the identity of the tether group, and the nature of the catalytic system, bicyclo[4.1.0]heptenes can undergo a variety of transformations. Our studies have revealed the reaction patterns of bicyclo[4.1.0]heptenes which include thermal reactions, nucleophilic addition, and rhodium-catalyzed reactions, that can proceed both with and without opening of the cyclopropyl ring. The chemistry described in this review can be used to produce a variety of new compounds such as 2,4-pentadienals, 3-methylene-4-vinylcyclohex-1-enes, bicyclo[3.2.2]nonadienes, 1,6,7,9a-tetrahydrocyclohepta[c] pyrans and -pyridines, hexahydroisoquinolines, 4-oxa-6-azatricyclo[3.3.0.0^2,8]octanes, and heterotricyclo[3.3.1.0^2,8]nonanes.     

Effect of sloped die lip geometry on the operability window in slot coating flows using viscocapillary and two-dimensional models

As an indicator for determining the operability window in slot coating flow, the viscocapillary model considering various configurations of upstream and downstream slot die lips was tested and compared with Navier–Stokes two-dimensional model. Bead pressure and sloped lip angle conditions for uniform coating operation demarcated from leaking and bead break-up defects were quantitatively predicted from the position of upstream meniscus from both models. By comparing the results, it is confirmed that the viscocapillary model for many kinds of sloped die lips could predict the operability window accurately. It is also found that there exists vortex or recirculation regimes inside upstream and downstream coating bead regions, depending on the angles of sloped die lips, even for the stable coating flow. The flow control by die lip structure will be usefully applied to design the strategy for the reliable and optimal coating process, including vortex-free windows.     

Protein nanopatterns and biosensors using gold binding polypeptide as a fusion partner

An efficient strategy for immobilizing proteins on a gold surface was developed by employing the gold binding polypeptide (GBP) as a fusion partner. Using the enhanced green fluorescent protein (EGFP), severe acute respiratory syndrome coronavirus (SARS-CoV) envelope protein (SCVme), and core streptavidin (cSA) of Streptomyces avidinii as model proteins, specific immobilization of the GBP-fusion proteins onto the gold nanoparticles and generation of protein nanopatterns on the bare gold surface were demonstrated. The GBP-fused SCVme bound to gold nanoparticles successfully interacted with its antibody and showed changes in absorbance and color, allowing efficient diagnosis of SARS-CoV. The fusion proteins could be successfully immobilized on the gold surface by nanopatterning and microcontact printing as examined by atomic force microscopy and surface plasmon resonance analysis. The poly(dimethylsiloxane) microfluidic channels were created on the gold surface and were used for antigen-antibody and DNA-DNA interaction studies. Specific immobilization of GBP-EGFP fusion protein and its interaction with the antibody in the microchannels could be demonstrated. By immobilizing the DNA probe through the use of GBP-fused cSA, specific hybridization of the target DNA prepared from Salmonella could also be achieved. The GBP-fusion method allows immobilization of proteins onto the gold surface without surface modification and in bioactive forms suitable for studying protein-protein, DNA-DNA, and other biomolecular interaction studies. Furthermore, these studies can be carried out in a microfluidic system, which allows high-throughput analysis of biomolecular interactions.     

Microstructural studies of PMMA impregnated mortars

Studies on cement concrete microstructures are carried out to explain experimentally observed phenomenon and for modeling of concrete at the macroscopic level. In this article, the preparation of polymer impregnated mortar (PIC) is carried out by partially or fully replacing the pores in the cement mortars (OPC) by PMMA. The effect of this polymer impregnation on density and morphology of the cement matrix is studied. The microstructural changes in the mortar, on exposure of these specimens to hydrochloric acid and sea water for 7 and 28 days, are also investigated in this article. The above studies indicated that the polymer addition decreased the voids in the mortar thereby preventing leaching of water soluble salts present in the OPC. It was observed that the polymer also prevented the external chemical media from permeating into the cement matrix and undergoing interactions with it. It is concluded that the durability and chemical resistance properties of the PIC are better compared with OPC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010