Cationic liposomes are known to be useful tools for gene transfection. However, the relation between transfection efficiency and physicochemical properties of liposomes has not been well understood. Here, we synthesized eight cationic derivatives of cholesterol which contain a tertiary amino head group with a different spacer arm. Transfection of plasmid pSVZCAT DNA into cells was done by cationic liposomes made of a mixture of dioleoylphosphatidylethanolamine (DOPE) and each cationic cholesterol derivative. At the same time we measured zeta potential of cationic liposomes by laser Doppler spectroscopy. The present results indicated that zeta potentials of cationic liposomes were well related to transfection activity of pSV2CAT DNA. This suggested that zeta potential of cationic liposomes is one of important factors which control gene transfection.
The aim of the present study was to evaluate the bonding durability of resin-based luting cement to partially stabilized tetragonal zirconia (Y-TZP) achieved by combination treatment of tribochemical (TBC) treatment and two different phosphate acid ester monomers. Two phosphate acid ester monomers (EP: Epricord opaque primer, AZ: AZ primer) were applied to each surface modification followed by application of resin-based luting cement (Rely-X ARC). Bonding specimens were placed in deionized water at 37°C and stored for 24 h. The other groups were subjected to 30,000 cycles of a thermal stress for the durability test. Shear bond tests were done using a universal testing machine at 1 mm/min. Shear bond strengths of combination treatments using EP and AZ on TBC treatment after thermal stress showed no significant difference (p>0.05) compared with those of storage after 24 h. Combination treatment using phosphoric acid ester monomer could achieve a durable bond.
The crystal structures of poly(di-n-butyl silane) and poly(di-n-pentyl silane) have been determined by comparing the experimental x-ray diffraction paltern with the theoretical pattern.The side-chain conformation i s mostly determined by the intramolecular steric hindrace as well 3s the van der Wmls interaction between the side chains. The Si backbone conformation of both crystals is a 3 helix. which 1s mainly determined by the intramolecular van der Waals interaction between the nearest-neighbour side chains. On the other hand. the Si backbone conformation of both crystals after a pressure treatment of 1500 MPa is all tmns. which is caused by the YM der Wads interaction between the side chains attached to the second-nearest-neighbour Si atoms.In all c~ses, one of the two CSi-C-C groups in Si(OHql3 or Si(C%Hu)2 is an essentially Irum conformation. whereas the other C-C-Si< gmup has a ci.r-like conformation, which is different from that generally accepted.
This paper describes the reasonable molecular configuration and inter-molecular packing of the poly(di-n-hexyl-silane) crystal. The crystal lattice is determined using a wide-angle X-ray diffraction method for the powdered specimen. The experimental diffraction pattern is compared with the theoretical one, in order to clarify the atom positions in the unit cell. The obtained unit cell contains the two polymer chains having an all-trans silicon backbone. The hexyl substituents are found to be asymmetrical conformations because of the steric hindrance. The orientation of the prepared thin film is also discussed on the basis of the obtained crystal structure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.