Tapping mode AFM evidence for an amorphous reticular phase in a condensation-cured hybrid elastomer: alpha,omega-dihydroxypoly(dimethylsiloxane)/poly(diethoxysiloxane)/fumed silica nanoparticles

A new surface phenomenon is reported for hybrid nanocomposites comprising (1) a low Tg poly(dimethylsiloxane) (PDMS) phase cross-linked by (2) a siliceous phase (SP) generated by in situ hydrolysis/condensation of poly(diethoxysiloxane) (PDES), and (3) fumed silica nanoparticles (FSN). After ambient temperature cure, tapping mode atomic force microscopy (TM-AFM) easily reveals near-surface FSN. For nanocomposites with higher PDES content, FSN surprisingly "disappear" after a further cure at 100 degrees C. The observation is explained by further condensation of extant siliceous fragments creating an amorphous reticular phase, which acts as a mechanical barrier between the FSN and the AFM tip.     

Re-revision of the stereo structure of piperidine lactone,an intermediate in the synthesis of febrifugine

The stereo structure of piperidine lactone (3), an intermediate of the antimalarial agent febrifugine ((+)-1) prepared by a synthetic method, was re-revised to the cis-form from the trans-form.     

Solvent effect on helicity induction of zinc bilinone bearing a chiral auxiliary at the helix terminal

Solvent effects on helicity induction in zinc bilinone (ZnBL) derivatives bearing chiral auxiliaries at their 19-positions were investigated by using circular dichroic spectroscopy and (1)H NMR experiments. In ZnBLs 1 and 2, which possess (R)-2-methyl-1-phenylpropyloxy and (R)-1-phenylethyloxy groups at their 19-positions, respectively, the efficiency of helicity induction was significantly affected by employed solvents (78-95% de in 1 and 33-89% de in 2). The free energy changes of the P-M interconversion of 1 and 2 were linearly in proportion to reduction in polarizability of solvents: lower polarizability of solvents led to better efficiency of helicity induction in 1 and 2. With the support of the (1)H NMR study in addition to the molecular modeling previously reported, it was indicated that the solvophobic van der Waals interaction between the alkyl group in the chiral auxiliary and the A-ring of the bilinone skeleton in the preferred conformer plays a crucial role in determining the efficiency of helicity induction in 1 and 2.     

Screening for Oral Cancer Using Electrochemical Telomerase Assay

Electrochemical telomerase assay (ECTA) developed by our group was evaluated in an oral cancer screening using exfoliated oral cells and tissues obtained from patients of oral cancer, mucosa associated disease, or healthy volunteers. Telomerase activity from ECTA is correlated with hTERT mRNA expression level using a real‐time PCR and was increasing in the following order: healthy volunteer group<mucosa associated disease group<oral cancer group. Sensitivity and specificity of ECTA were 88 % and 72 %, respectively when used 17 % of the threshold value based on the receiver operating characteristic curve in ECTA data.