Polydimethylsiloxane (PDMS) has been synthesized by ring-opening polymerization of octamethylcyclotetrasiloxane (D4) in microemulsion with acidic catalyst. The structure and properties of microemulsion were characterized by Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), Photo Correlation Spectroscopy (PCS). The effect of the variation in pH value, amoun...

Traction–separation relations can be used to represent the adhesive interactions of a bimaterial interface during fracture. In this paper, a direct method is proposed to determinemixed-mode traction– separation relations based on a combination of global and local measurements including load-displacement, crack extension, crack tip opening displacement, and fracture resistance curves. Mixed-mode...

The title compound, C(21)H(32)O(3), results from modifications of the A and D rings of the aromatase substrate androstenedione. Ring A adopts a conformation between 10β-sofa and 1α,10β half-chair. Rings B and C are in slightly flattened chair conformations. Ring D approaches a 13β-envelope conformation, probably due to the acet-oxy substituent, and shows a very short Csp(3)-Csp(3) bond next to ...

Epoxy-based nanocomposites were fabricated with different content of colloidal silica nanoparticles such as 10.0, 20.0 and 30.0 wt %, through solution casting. The covalent bonding interfaces, resulting from a ring-opening reaction between silica nanoparticles and epoxy matrix were confirmed by the Fourier transform (FT-IR) infrared spectroscopy. These nanocomposites were characterized for ...

Derivatives of bile acids with substituents in Ring C have been described in the preceding papers of this series (l-6). It is the purpose of this paper to assign the probable stereochemical configurations for these compounds. As desoxycholic acid (I)l is a convenient reference compound, it will first be necessary to discuss briefly the spatial arrangement of certain portions of this bile acid. ...

Aziridines can undergo a range of ring-opening reactions with nucleophiles. The regio- and stereochemistry of the products depend on the substituents on the aziridine. Aziridine ring-opening reactions have rarely been used in radiosynthesis. Herein we report the ring opening of activated aziridine-2-carboxylates with [(18)F]fluoride. The aziridine was activated for nucleophilic attack by substi...

The diversity-oriented synthesis of acyclic nucleosides has been achieved via ring-opening of vinyl cyclopropanes with purines. With Pd2(dba)3·CHCl3 as a catalyst, the 1,5-ring-opening reaction proceeded well and afforded N9 adducts as the major form, in which the C=C bonds in the side chain were exclusively E-form. In the presence of AlCl3, the 1,3-ring-opening reaction occurred smoothly, givi...

an epoxy resin was modified by silica nanoparticles and cured with an anhydride. the particles with different batches of 12, 20, and 40 nm sizes were each distributed into the epoxy resin ultrasonically. electron microscopy images showed that the silica particles were well dispersed throughout the resin. tensile test results showed that young’s modulus and tensile strength increased with the vo...