Spontaneous formation of dye-functionalized gold nanoparticles using reverse micellar systems

Detailed exploratory and mechanistic investigations on spontaneous formation of dye-functionalized gold nanoparticles (GNPs) using dye-based reverse micellar systems are described in this publication. The accumulated results from spectroscopic and microscopic investigations demonstrated that water molecules confined within nanoscopic enclosure of the self-assembled reverse micelles played critical role in the redox processes of aurate ions to produce GNPs, which are assumed to have approximately constant size distributions. The resulting dye-functionalized GNPs were found to offer their absorption and fluorescence emission tunability by changing the medium polarity as well as to exhibit excellent film-forming properties to give optically homogeneous polystyrene thin films. These key findings in addition to broad applicability of the self-assembling process with a variety of dye analogues have led to a conclusion that the protocol presented here serves as a versatile synthetic method to provide a potential convenience for future development of new organic-inorganic hybrid nanomaterials.     

A compact TOF-SANS using focusing lens and very cold neutrons

We are developing a high-resolution small angle neutron scattering instrument for very cold neutrons (VCN). Our concept includes a magnetic lens for focusing of the beam at the detector plane. The lens consists of one permanent-magnet sextupole array rotating outside another stationary sextupole array, to focus a pulsed white beam of neutrons. Thus the instrument operates in time of flight mode. The prototype magnetic lens has a bore of 15 mm diameter and length of 66 mm, producing a magnetic field gradient oscillating from 1.5×10⁴ to 5.9×10⁴ T/m², with frequency ≤25 Hz. A torque-canceling magnet around the lens suppresses the torque of rotation from the outer array to 1/3.We have demonstrated the performance of the lens, over wavelength range from 30 to 48 Å, on the PF2-VCN beam line at the Institut Laue-Langevin, France. The focused beam image was the same size as the source, without chromatic aberration, with focal length of 1.14 m. We also studied the performance of this configuration for high-resolution SANS, in a compact geometry (just 5 m long). The measurable q range of this system was 0.009 Å⁻¹≤q≤0.3 Å⁻¹ or 0.004 Å⁻¹≤q≤0.08 Å⁻¹ for sample to detector distances of 100 and 465 mm, respectively. Here, we present the results of our lens characterization study along with the SANS results on a tri-block copolymer (F127 Pluronic) and on a stretched polymer blend (with the Shish-Kebab structure).     

On a Kaehler hypersurface with the cyclic Ricci semi-symmetric tensor

The purpose of the present paper is to prove that a Kaehler hypersurface with the cyclic Ricci semi-symmetric tensor is locally symmetric.     

Complementary hydrogen-bonding between thymidine-based low molecular-weight gelator and polynucleotide in organic media

We have found that aggregation mode and gelation property of thymidine-based organogelator are affected by the addition of its complementary polynucleotide in organic media.     

Cooperative molecular field effect and induced orientational ordering effect in polar liquid crystalline films on metals

Using the in situ measurements of the surface potential built across the evaporated liquid crystalline 4-n-pentyl-4'-cyanobiphenyl (5CB) films on metal electrodes with different work functions, we studied the cooperative molecular field effect (CMFE) that assists carrier injection from electrodes and the induced orientational reordering in evaporated liquid crystalline molecules on metals. The surface potential increased, and then became constant after the 5CB monomolecular layer was formed. It was shown that the CMFE accompanying orientational reordering accounts for the metal work function dependence of the surface potential. Finally, the orientational reordering is discussed in terms of the anchoring energy.     

Organogels of 8-quinolinol/metal(II)-chelate derivatives that show electron- and light-emitting properties

8-quinolinol/copper(II)-, palladium(II)-, and platinum(II)-chelate-based organogelators (1 M) and their nongelling reference compounds (2 M) were synthesized. Complexes 1 M could gelate various organic solvents at very low concentrations. Electron microscope measurements gave visual images of well-developed fibrous structures characteristic of low-molecular-weight organogels. UV/Vis and FTIR spectroscopy revealed that the good gelation ability of 1 M arises from the pi-pi interactions of the chelate moieties and the hydrogen-bond interactions among the amide groups. Very interestingly, field emission performances of the nanofibers prepared from the 1 M gels are evidently different depending on the electronic states of the three kinds of central metals. In addition, the 1 Pt gel shows unique thermo- and solvatochromism of visible and phosphorescent color in response to a sol-gel phase transition. Furthermore, the 1 Pt gel possesses an attractive ability to inhibit dioxygen quenching of excited triplet states, which increases the phosphorescence quantum yield of this gel. This effect is attributed to the isolation effect of the phosphorescent chelate moiety from the dioxygen-containing solution phase.     

Potential of digital holography in particle measurement

This paper describes the potential power of digital holography in particle measurement and its expected development in the near future. In digital holography, image reconstruction is carried out numerically on a computer using observed hologram patterns and some quantitative information can be derived from the reconstructed images. In this paper, the basic concept and procedure of digital in-line holography are shown mainly for particle depth measurement and the performance test results obtained in numerical simulations and experiments are demonstrated to examine the potential of the present method.