Novel oligonucleotide carrier as scavenger for reactive oxygen species

A novel oligonucleotide carrier which can scavenge ROS is described. The synthesized graft polymer is composed of a PEG segment and a TEMPO‐containing hydrophobic segment for scavenging ROS. This graft polymer can form a PIC through electrostatic interaction with oligonucleotides such as siRNA. The amount of ROS was monitored by fluorescence measurements using H₂DCFDA as a probe, and it was confirmed that the ROS level was effectively suppressed. The cellular uptake of PIC containing the fluorescence‐labeled oligonucleotide was evaluated by fluorescence microscopy. Delivered siRNA suppressed the expression of the mRNA. The prepared graft copolymer is thus a promising candidate as a novel oligonucleotide carrier which also reduces ROS damage generated by cationic polymer carriers.

     

Examination of Dislocation Mechanism on Grain Boundary Sliding in High Angle Grain Boundaries by Stress Change Test

In order to understand the factors dominating grain boundary sliding, stress change tests and stress reversal tests were conducted on aluminum bicrystal specimens with high angle grain boundaries. It is found that small change in stress results in the remarkable change in the rate of grain boundary sliding. Stress reversal tests showed that grain boundary slide hardening does not work for the sliding to the direction opposite to that before the stress reversal. Mean internal stresses for the dislocations contributing to grain boundary sliding are experimentally measured by a method consisting of stress change and annealing. It is found that the velocity of dislocations in the grain boundary is in proportion to the mean effective stress.     

Catalytic diversity of diene complexes of niobium and tantalum on polymerizations of ethylene,norbornene, and methyl methacrylate

Half‐metallocene diene complexes of niobium and tantalum catalyzed three‐types of polymerization: (1) the living polymerization of ethylene by niobium and tantalum complexes, MCl₂(η⁴‐1,3‐diene)(η⁵‐C₅R₅) ( 1‐4 ; M = Nb, Ta; R = H, Me) combined with an excess of methylaluminoxane; (2) the stereoselective ring opening metathesis polymerization of norbornene by bis(benzyl) tantalum complexes, Ta(CH₂Ph)₂(η⁴‐1,3‐butadiene)(η⁵‐C₅R₅) ( 11 : R = Me; 12 : R = H) and Ta(CH₂Ph)₂(η⁴‐o‐xylylene)(η⁵‐C₅Me₅) ( 16 ); and (3) the polymerization of methyl methacrylate by butadiene‐diazabutadiene complexes of tantalum, Ta(η²‐RN=CHCH=NR)(η⁴‐1,3‐butadiene)(η⁵‐C₅Me₅) ( 25 : R = p‐methoxyphenyl; 26 : R = cyclohexyl) in the presence of an aluminum compound ( 24 ) as an activator of the monomer.