Carpetlike dense‐layer formation in a polyelectrolyte brush at the air/water interface

A carpetlike dense‐layer formation between a hydrophobic layer and a polyelectrolyte brush layer has been found in the monolayers of an ionic amphiphilic diblock copolymer, poly(1,1‐diethylsilacyclobutane)_m‐block‐poly(methacrylic acid)_n, on a water surface by an X‐ray reflectivity technique. By detailed analysis, we have found that the hydrophilic layer under the water is not a simple layer but is divided into two layers, that is, a carpetlike dense methacrylic acid (MAA) layer near the hydrophobic layer and a polyelectrolyte brush layer. We have also confirmed that a well‐established polyelectrolyte brush is formed only for the m:n = 43:81 polymer monolayer: For m:n = 40:10 and m:n = 45:60 polymer monolayers, only a dense MAA layer is formed. This dense‐layer formation should be the origin of the interesting hydrophobic‐layer thickness variation previously reported; The hydrophobic‐layer thickness takes a minimum as a function of the hydrophilic chain length at any surface pressure studied. An overview of the data for three samples with different chain lengths (m:n = 40:10, 45:60, or 43:81) has shown that the thickness of this dense layer is 10–20 Å and is independent of the surface pressure and polymerization degree of poly(methacrylic acid) (PMAA) in the range studied. This dense‐layer formation is explained by the reasonable speculation that contact with PMAA is thermodynamically more stable than direct contact with water for the diethylsilacyclobutane (Et₂SB) layer on water. In this sense, the dense layer acts like a carpet for the hydrophobic Et₂SB layer, and a 10–20‐Å thickness could be a critical value for the carpet. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 1921–1928, 2003     

A novel method for the assay of alpha-glucosidase inhibitory activity using a multi-channel oxygen sensor.

The quantification of glucose by using a multi-channel dissolved oxygen (DO) meter (DOX96) with immobilized glucose oxidase (GOD) and mutarotase (MUT) was performed. An evaluation of the inhibitory activities for alpha-glucosidase (AGH) by modifying our batch-type pseudo-in vivo assay system [Oki et al.; Biol Pharm. Bull., 2000, 232, 1084] was also performed using a DOX96. When 45 U/well GOD and 18.75 U/well MUT were immobilized on the surface of a gelatin membrane on the electrodes, the response shown by the decrease percent of DO (%) obtained with 8 electrode wells in the same row was linear with the glucose concentration up to 3.3 mM and a correlation coefficient larger than 0.9. To estimate the AGH inhibitory activity, AGH-immobilized Sepharose supports in the well of a silent screen plate were used. The IC50 values of acarbose and 1-deoxynojirimycin, a medicinal inhibitor for diabetes, were 0.70 +/- 0.08 microM and 0.40 +/- 0.13 microM, respectively, and coincided well with those by a pseudo-in vivo assay.     

Entanglement measures with asymptotic weak-monotonicity as lower (upper) bound for the entanglement of cost (distillation)

We propose entanglement measures with asymptotic weak-monotonicity. We show that a normalized form of entanglement measures with the asymptotic weak-monotonicity are lower (upper) bound for the entanglement of cost (distillation).     

Measurement of Wavelength Dependence of Electro-Optic Coefficients r22 of Non-doped and 5% MgO-doped Congruent LiNbO3 Crystals and 1.8% MgO-doped Quasi-stoichiometric LiNbO3 Crystal by Multiple Reflection Interference Method

The electro-optic coefficient r ₂₂ in the wavelength range from 409 to 1580 nm was measured for non-doped and 5% MgO-doped congruent LiNbO₃ crystals and 1.8% MgO-doped quasi-stoichiometric LiNbO₃ crystals in a simple optical system using a multiple reflection interference method capable of producing high-precision results without the application of antireflection film to the end faces of the crystal. The influence of the manufacturing errors of the electrooptic crystals was discussed on the measurement of the r ₂₂ coefficient. The experimental errors are less than approximately 0.5% in the wavelength range from 409 to 1064 nm and approximately 1% from 1340 to 1580 nm. It was further shown that polarizing of the laser along X axis resulted in highly accurate measurement of the r ₂₂ of LiNbO₃ crystals.     

Persistence of pierisin-1 activities in the adult cabbage white butterfly,Pieris rapae,during storage after killing

Crude extracts from larvae, pupae and adults of cabbage white butterflies, Pieris rapae and Pieris brassicae, and green-veined butterfly, Pieris napi, have an ability to induce apoptosis in the human cancer cell lines. As apoptosis inducing protein, pierisin-1 and -2 have been isolated from pupae of P. rapae and P. brassicae, respectively, and shown to exhibit DNA ADP-ribosylating activity. Although the highest activity was detected in the late phase of larvae and early phase of pupae, certain activity was found in adult butterflies. In order to investigate distribution of substances having pierisin-like activities in butterflies, many species need to be analyzed. However, fresh samples of larvae and pupae are hard to obtain, especially if samples are of scarce species or from overseas. The usage of adult butterflies is practical to examine the distribution of pierisin-like activity in many species. In this study, we examined the cytotoxicity of crude extracts from adults of P. rapae against HeLa cells and DNA ADP-ribosylation ability during storage for 1, 2 and 8 weeks at room temperature after killing adult butterflies after eclosion. Body weights decreased to 18% for 8 weeks through dehydration. Cytotoxicity of samples from butterfly kept for 1, 2 and 8 weeks decreased to 47, 39 and 22%, respectively, of the control value. DNA ADP-ribosylating activity of the samples also decreased to 30, 27 and 23%. Similar reduction was observed on western blot analysis with anti-pierisin-1 antibody. Fortunately, these results suggest that cytotoxic and DNA ADP-ribosylating activity persists to some extent in the body after killing, at least for 8 weeks. Thus, butterfly adult samples kept for two months at room temperature can still be useful for examination of the presence of substance having pierisin-like activity.     

Preparation of self-assembled fluorinated molecular aggregates, fluorescein nanocomposites: an extremely enhanced light absorption in nanocomposites

Self-assembled fluorinated molecular aggregates formed by fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomers, N,N-dimethylacrylamide oligomers, and acrylic acid oligomers in methanol could selectively recognize fluoresceins as guest molecules to form a new class of fluorinated aggregates-fluorescein nanocomposites. These fluorinated fluorescein nanocomposites that are obtained exhibit an extraordinarily enhanced light absorption (_max ca. 440 nm) compared to that (_maxs 452, 480 nm) of the parent fluorescein in the absence of fluorinated aggregates.     

Tailored sinc pulses for uniform excitation and artifact-free radio frequency time-domain EPR imaging

A method to generate shaped radiofrequency pulses for uniform excitation of electron spins in time-domain radio frequency (RF) electron paramagnetic resonance (EPR) imaging is presented. A commercial waveform generator was integrated with the transmit arm of the existing time-domain RF-EPR spectrometer to generate tailored excitation pulses with sub-nano second resolution for excitation with a 90 degrees flip-angle. A truncated sinc [sin(x)/x] pulse, tailored to compensate for the Q-profile (RF frequency response) of the resonator, was shown to yield images from phantom objects as well as in vivo images, with minimal distortion. These studies point to the advantages in using shaped sinc pulses to achieve improved uniform excitation over a relatively wide bandwidth region in time-domain RF-EPR imaging (RF-FT-EPRI).     

Purification through Zeno-like measurements

A series of frequent measurements on a quantum system (Zeno-like measurements) is shown to result in the "purification" of another quantum system in interaction with the former. Even though the measurements are performed on the former system, their effect drives the latter into a pure state, irrespectively of its initial (mixed) state, provided certain conditions are satisfied.     

Visualization and numerical analysis of stress waves in blasting process

Visualization studies were performed both experimentally and theoretically to observe stress wave propagation in a material and its interaction with the free surface of the material in a blasting process. PMMA (polymethyl-methacrylate) plates were used as a transparent material. The stress wave was generated by initiation of an electric detonator. The stress waves in the PMMA specimen with the right-angled corner were observed by means of the shadowgraph system using a Q switched ruby laser as a light source. In addition to the experiment, a numerical analysis using smoothed particle hydrodynamics (SPH) was also carried out to clarify the dynamic behavior of stress waves in the blasting process. Transmittance and reflection of the stress wave at the free surface could be visualized by both the experiment and the numerical analysis.     

Determination of a merocyanine J-aggregate structure and the significant contribution of the electric dipole interaction to the exciton band wavelength

The molecular alignment of a merocyanine (MC) J-aggregate monolayer at the air-water interface was determined by a grazing incidence x-ray diffraction method. The obtained molecular arrangement apparently shows that the conventional formula, which accounts only for the transition dipole interaction, is not sufficient to figure out the exciton band wavelength, suggesting the importance of the electric dipole (ED) interaction. We derived a simple formula for the ED interaction energy under an extended dipole approximation and clarified the ED contribution in the MC J aggregate.