Pyrene aromatic arrays on RNA duplexes as helical templates

RNA oligomers having multiple (2 to 4) pyrenylmethyl substituents at the 2'-O-sugar residues were synthesized. UV-melting studies showed that the pyrene-modified RNAs could form duplexes with complementary RNA sequences without loss of thermal stability. Absorption, fluorescence, and circular dichroism (CD) spectra revealed that the incorporated pyrenes projected toward the outside of A-form RNA duplexes and assembled in helical aromatic arrays along the minor grooves of the RNA duplexes. Results of computer simulations agreed with the assembled structures of the pyrenes. The helical pyrene arrays exhibited remarkably strong excimer fluorescence, which was dependent on the sequence contexts of RNA duplexes.     

Cell Spheroid Formation on the Surface of Multi-Block Copolymers Composed of Poly(2-methoxyethyl acrylate) and Polyethylene Glycol

3D structured cells have great drug screening potential because they mimic in vivo tissues better than 2D cultured cells. In this study, multi-block copolymers composed of poly(2-methoxyethyl acrylate) (PMEA) and polyethylene glycol (PEG) are developed as a new kind of biocompatible polymers. PEG imparts non-cell adhesion while PMEA acts as an anchoring segment to prepare the polymer coating surface. The multi-block copolymers show higher stability in water than PMEA. A specific micro-sized swelling structure composed of a PEG chain is observed in the multi-block copolymer film in water. A single NIH3T3-3-4 spheroid is formed in 3 h on the surface of the multi-block copolymers with 8.4 wt% PEG. However, at a PEG content of 0.7 wt%, spheroid formed after 4 days. The adenosine triphosphate (ATP) activity of cells and the internal necrotic state of the spheroid change depending on PEG loading in the multi-block copolymers. As the formation rate of cell spheroid on low-PEG-ratio multi-block copolymers is slow, internal necrosis of cell spheroid is less likely to occur. Consequently, the cell spheroid formation rate by changing the PEG chain content in multi-block copolymers is successfully controlled. These unique surfaces are suggested to be useful for 3D cell culture.     

High-rate Deposition of Polycrystalline Diamond Film Using Time-series Exposure of Modulated/Non-modulated Induction Thermal Plasmas at Different Flow Rates of Carbon Source Gas

Plasma Chemistry and Plasma Processing - In this paper $$\hbox {CH}_4$$ / $$\hbox {H}_2$$ gas flow rate effect on polycrystalline diamond deposition was studied using a time-series exposure...     

Development and flow evaluation of electro-rheological nano-suspensions

An attempt has been made to develop a candidate for electro-rheological (ER) nano-suspensions based on anatase titanium dioxide with a particle diameter around 300 nm. The micro-gap flow behavior and microstructure were evaluated for a suspension with a particle volume fraction of 8.8 vol.%. The ER effect was investigated for the nano-suspension. The effect of shearing time on the ER responses was also investigated. The ER effect was discussed in comparison to the effect previously reported for the nano-suspension based on rutile titanium dioxide with a particle diameter around 15 nm.     

(Hyper)polarizability density analysis for open-shell molecular systems based on natural orbitals and occupation numbers

We have developed a method for analyzing the (hyper)polarizabilities of open-shell molecular systems. This method employs the (hyper)polarizability densities based on the natural orbitals and occupation numbers, which enables us to analyze the contributions of odd electrons having various open-shell (diradical) characters. Within broken-symmetry, i.e., spin-unrestricted, single-determinant molecular orbital and density functional theory approaches, we can also remove the spin contamination effects on these quantities through spin projection. To do that, an approximate spin projected method has been elaborated and applied to the analysis of the (hyper)polarizability of multi-radical systems. As examples, typical open-shell singlet systems, 1,3-dipoles and rectangular graphene nanoflakes, are examined.     

Theoretical Study on the Second Hyperpolarizabilities for Small Radical Systems

We study the second hyperpolarizabilities (ɣ) for anion, neutral and cation radicals and find that magnitudes of ɣ (| ɣ |) of the radicals are sensitively influenced by features of each charged state. It is also found that electron-correlation dependence of ɣ could be related to the resonance structure contributing to the ground state of the molecules.This paper was originally presented at the 5th International Conference on NEAR FIELD OPTICS and RELATED TECHNOLOGIES (NFO-5), which was held on December 6–10, 1998 at Coganoi Bay Hotel, Shirahama, Japan, in cooperation with the Japan Society of Applied Physics and Mombusho Grant-in Aid for Scientific Research on Priority Areas “Near-field Nano-optics” Project, sponsored by Japan Society for the Promotion of Science.