Drastic enhancement of excess electron-transfer efficiency through DNA by inserting consecutive 5-phenylethynyl-2'-deoxyuridines as a modulator

5-(Phenylethynyl)-2'-deoxyuridine ((Ph)U) was consecutively incorporated into oligodeoxynucleotides as an electron transport modulator for regulating DNA-mediated excess electron transfer (EET). Upon photoexcitation of the ethynylpyrene chromophore, extremely high EET efficiencies through DNA containing consecutive (Ph)Us were observed using 5-bromouracil as a distal electron trap.     

Molecular chirality and chiral capsule-type dimer formation of cyclic triamides via hydrogen-bonding interactions

Chiral properties of bowl-shaped cyclic triamides bearing functional groups with hydrogen-bonding ability were examined. Chiral induction of cyclic triamide 3a was observed by addition of chiral amine in solution, and chiral separation was achieved by simple crystallization to afford chiral capsule-type dimer structure of 4a.     

Is the 7/2(1)- isomer state of 43S spherical?

We report on the spectroscopic quadrupole moment measurement of the 7/2(1)(-) isomeric state in (16)(43)S(27) [E*=320.5(5) keV, T(1/2)=415(3) ns], using the time dependent perturbed angular distribution technique at the RIKEN RIBF facility. Our value, |Q(s)|=23(3) efm(2), is larger than that expected for a single-particle state. Shell model calculations using the modern SDPF-U interaction for this mass region reproduce remarkably well the measured |Q(s)|, and show that non-negligible correlations drive the isomeric state away from a purely spherical shape.     

On-bead screening of a library to detect host-guest complexation by an aniline reporter

We developed a new labeling reagent and a color assay system in water to detect binding between target molecules and library members on beads, which is free of label-induced artifacts that can cause misleading results.     

First-principles study on proton dissociation properties of fluorocarbon- and hydrocarbon-based membranes in low humidity conditions

We present a theoretical study on the proton dissociation properties of the membranes for polymer electrolyte fuel cells. A density functional theory method is used to study the influence of fluorocarbon and hydrocarbon backbones on proton dissociation, the interaction of water molecules with the sulfonic acid group, and the energy barriers for proton dissociation. Better proton dissociation properties of CH(3)SO(3)H compared to CF(3)SO(3)H are observed from statistical analyses of the optimized structures for both systems. However, the calculated energy barriers for proton dissociation are lower for CF(3)SO(3)H than for the CH(3)SO(3)H system. At the same time, the interaction of water molecules is stronger for CH(3)SO(3)H than for CF(3)SO(3)H. Also, the analysis of the hydrogen-bonding network in both systems shows that the number of hydrogen bonds formed around the sulfonic acid group in CH(3)SO(3)H is larger than that in CF(3)SO(3)H. Therefore, the decrease of the energy barrier with increasing number of coordinating water molecules, pronounced in the case of CH(3)SO(3)H, may lower the barrier, which enhances good proton conductivity of a hydrocarbon-based polymer in low humidity conditions. Thus the hydration ability of a sulfonic acid group is an important factor for realizing better proton dissociation in low humidity conditions.     

Study on the reactivity of diarylmethane derivatives in supercritical alcohols media: reduction of diarylmethanols and diaryl ketones to diarylmethanes using supercritical 2-propanol

We found that diarylmethanols and diaryl ketones were smoothly reduced to the corresponding diarylalkanes using supercritical 2-propanol in good yields. Furthermore, we determined the specific reaction of fluorene using supercritical methanol at high temperature.     

Enhanced performance of a filter-sensor system

In this paper are addressed two important, but seemingly unrelated issues: long term performance of a gas sensing array and performance of an air purification unit. It is shown that when considered together, the system can be regarded as a "smart filter". The enhancement is achieved by periodic differential sampling and measurement of the "upstream" and "downstream" gases of a filter. The correctly functioning filter supplies the "zero gas" from the downstream for the continuous sensor baseline correction. A key element in this scheme is the synthetic jet that delivers well-defined pulses of the two gases. The deterioration of the performance of the "smart filter" can be diagnosed from the response pattern of the sensor. The approach has been demonstrated on removal/sensing of ammonia gas from air.     

Facile synthesis of aryl ether dendrimer from unprotected AB2 building blocks using thionyl chloride as an activating agent

[structure: see text] A novel, rapid, inexpensive, and highly efficient convergent approach for the synthesis of a Fréchet- type aryl ether dendrimer using thionyl chloride has been developed. In this method, the purification of each dendron and a dendrimer occurs by recrystallization, extraction, and precipitation. The MALDI-TOF MS spectrum supported the formation of the G2, G3, and G4 dendrons and the star-shaped G4 dendrimer.     

A twin-type airflow pulse ionization chamber for continuous alpha-radioactivity monitoring in atmosphere

A simple and inexpensive twin-type airflow pulse ionization chamber was developed for the continuous monitoring of alpha-radioactivity in atmosphere under high humidity condition. The symmetrical structure of the twin-type ionization chamber was effective in the improvement of the ratio of signal to noise in the measurement of pulses induced by alpha-rays. Outdoor alpha-ray measurement was well performed with this ionization chamber by applying sufficiently high bias voltage to the electrodes, except for at very high humidity conditions. It was confirmed that the declination of the counting efficiency due to wetting was easily recovered by the dry-up of the inside of the chamber. Alpha-radioactivity from radon and other alpha-emitting radionuclide in atmosphere was satisfactorily monitored by the detector.