Conductance Study of 1 : 1 19-Crown-6 Complexes with Various Mono- and Bivalent Metal Ions in Water

Formation constants (ML) of 1 : 1 19-crown-6 (19C6) complexes with mono- (M+) and bivalent metal ions (M2+) were determined in water at 25 °C by conductometry. The KML value of 19C6 for M+ and M2+ decreases in the order Rb+ K+ > Tl+ > Na+ = Ag+ > Li+ Cs+ and Pb2+ > Ba2+ > Sr2+ > Cd2+ > Ca2+, respectively. The selectivity for the neighboring alkali metal ions in the periodic table is lower for 19C6 than for 18-crown-6 (18C6) except for the case of Rb+ and Cs+. The same is true for the alkaline earth metal ions. Generally, the KML values of 19C6 with M2+ are greater than those with M+. For Na+ and the ions which are smaller in size than Na+ (Li+, Ca2+, Cd2+), the KML value is larger for 19C6 than for 18C6, but the contrary holds for all the other ions of larger sizes than Na+. The limiting ionic molar conductivity (°) of the 19C6–K+ complex in water at 25 °C was determined to be 43. Although 19C6 is larger than 18C6, the 19C6–K+ complex is much more mobile in water than the 18C6–K+ complex.     

Simultaneous determination of metabolites of trimethylbenzenes,dimethylbenzylmercapturicacid and dimethylhippuric acid,in human urine by solid-phase extraction followed by liquid chromatography tandem mass spectrometry

We describe a novel method for the determination of three kinds of dimethylbenzylmercapturic acids (DMM) and six kinds of dimethylhippuric acids (DMH), found in urine as metabolites of trimethylbenzenes, based on liquid chromatography/electrospray ionization tandem mass spectrometry. A solid-phase extraction procedure was used for the extractions of DMM and DMH from a urine sample, and the separation was performed on a reversed-phase C(30) column. The analytes were ionized by electrospray in the positive-ion mode. Operating in the multiple reaction monitoring mode, the linearity of the relative mass spectrometric responses to the internal standard versus analyte concentrations were established in the range 0.1-100 ng ml(-1). The extraction procedure was rapid and the relative standard deviations were below 5%. The detection limits of DMM and DMH in the urine by the proposed method were in the ranges 0.26-0.41 and 0.42-2.0 ng l(-1), respectively. Furthermore, DMM and DMH were detected in a urine sample from an individual who did not suffer from occupational exposure to trimethylbenzenes, by using this method.     

Preparation of colored latex containing oil-soluble dyes with high dye content by mini-emulsion polymerization

Polymer particles containing oil-soluble dyes (colored latex particles) were prepared by mini-emulsion polymerization. Copper phthalocyanine dyes and styryl dyes were used as oil-soluble dyes. Highly hydrophobic dyes played the role of hydrophobe by themselves and enabled the full incorporation of dyes in the latex without additional hydrophobes. Two phthalocyanine dyes having similar color were blended in a mini-emulsion polymerization so that the resulting colored latex showed enough strong color depth as a colorant. Colored latexes with high dye content (more than 30 wt% for phthalocyanine dye system and 40 wt% for styryl one) and with particle size less than 100 nm were obtained.     

Temperature variation of piezoelectric moduli in oriented poly(γ-methyl L-glutamate)

The real and imaginary components of the complex piezoelectric strain constant, which relates the polarization to the applied stress, have been determined for elongated films of poly(γ-methyl L -glutamate) over the temperature range ?170°C to +170°C at a frequency of 20 Hz. The variation of the piezoelectric constant with temperature is similar for both α-helical and β-form molecular conformations. The sign of piezoelectric polarization is opposite for L and D polymers. A simple model, representing the piezoelectric crystallites as embedded in nonpiezoelectric amorphous regions, is proposed to account for the piezoelectric temperature dispersion curves.     

Studies on the thermal ring-opening reactions of cis-3,4-bis(organosilyl)cyclobutenes

Three cis-3,4-bis(organosilyl)cyclobutenes were synthesized, and their thermal ring-opening reactions were studied. The ring-opening reaction of cis-3,4-bis(trimethylsilyl)cyclobutene proceeded remarkably faster than that of cis-3,4-dimethylcyclobutene. The significant rate acceleration was explained by assuming (i) stabilization of the transition state by electron delocalization from the cyclobutene HOMO to the Si-CH3 sigma* orbital, (ii) destabilization of the ground state by intramolecular interaction between the C-Si sigma orbitals and the pi orbital of cyclobutene, and (iii) through-space steric repulsion of the two bulky trimethylsilyl groups in a cis arrangement. The ring-opening reaction of unsymmetrical cis-3,4-bis(arylsilyl)cyclobutenes having electronically different arylsilyl groups was also examined. The inward preference increased in the order, p-CH3OC6H4-Si, C6H5-Si, p-CF3C6H4-Si, supporting the interpretation of the origin of the inward preference of silyl substituents on the basis of a stabilizing interaction between the cyclobutene HOMO and the Si-C sigma* orbital at the transition state.     

Time dilation of a bound half-fluxon pair in a long Josephson junction with a ferromagnetic insulator

The fluxon dynamics in a long Josephson junction with a ferromagnetic insulating layer is investigated. It is found that the Josephson phase obeys a double sine-Gordon equation involving a bound pi fluxon solution, and the internal oscillations of the bound pair acting as a clock exhibit Lorentz reductions in their frequencies regarded as a relativistic effect in the time domain, i.e., time dilation. This is the complement to the Lorentz contraction of fluxons with no clock. A possible observation scheme is also discussed.     

Effects of frequency characteristics of reverberation time on listener envelopment

Spatial impression perceived in a listening space comprises at least two components: one is auditory (apparent) source width (ASW) and the other is listener envelopment (LEV). Both ASW and LEV are affected not only by temporal but also by spatial structures of reflections. It has been clarified that ASW for symphony music is significantly affected by low-frequency components of source signals and reflections, but not by their high-frequency components. The objective of this work is to investigate whether LEV is affected by the frequency characteristics of source signals and reverberation sounds, which are known to contribute to the creation of LEV. In this study, three experiments were performed to clarify the effects of reverberation time (RT) and its frequency characteristics on LEV. In contrast to the case of ASW, the experimental results show that RTs both at high and low frequencies affect LEV.     

Cell patterning using a template of microstructured organosilane layer fabricated by vacuum ultraviolet light lithography

Micropatterning techniques have become increasingly important in cellular biology. Cell patterning is achieved by various methods. Photolithography is one of the most popular methods, and several light sources (e.g., excimer lasers and mercury lamps) are used for that purpose. Vacuum ultraviolet (VUV) light that can be produced by an excimer lamp is advantageous for fabricating material patterns, since it can decompose organic materials directly and efficiently without photoresist or photosensitive materials. Despite the advantages, applications of VUV light to pattern biological materials are few. We have investigated cell patterning by using a template of a microstructured organosilane layer fabricated by VUV lithography. We first made a template of a microstructured organosilane layer by VUV lithography. Cell adhesive materials (poly(d-lysine) and polyethyleneimine) were chemically immobilized on the organosilane template, producing a cell adhesive material pattern. Primary rat cardiac and neuronal cells were successfully patterned by culturing them on the pattern substrate. Long-term culturing was attained for up to two weeks for cardiac cells and two months for cortex cells. We have discussed the reproducibility of cell patterning and made suggestions to improve it.     

Double-acquisition: utilization of discarded coherences in a 2D separation experiment using the States method

We propose a new data-acquisition scheme for 2D separation experiments to save the spectrometer time by 1/2. This scheme, referred to as a double-acquisition scheme, is applicable to most of separation experiments with the hypercomplex time-domain data-acquisition scheme (the States method) for data collection.     

Theoretical and experimental studies on the thermal ring-opening reaction of cyclobutene having a stannyl substituent at the 3-position

The ring-opening reaction of 3-(trimethylstannyl)cyclobutene gave a mixture of the (Z)- and (E)-1,3-dienes, whereas that of 3-tert-butylcyclobutene exclusively afforded the (E)-1,3-diene due to the steric influences. The contrasting rotational behaviors suggest that there is some effect operating with the 3-stannylcyclobutene to stabilize the inward transition state, counteracting the steric influences. This contrasteric effect is ascribed to negative hyperconjugation. The stannyl group in the inward transition state accommodates electron density from the breaking sigma orbital of the cyclobutene into its low-lying tin-carbon sigma orbital. Theoretical studies supported this interpretation.