Influence of the swelling state of seed polymer particles with monomer on the morphology of micron-sized monodispersed composite polymer particles produced by seeded polymerization utilizing the dynamic swelling method

 Micron-sized mono-dispersed polystyrene (PS)/poly(n-butyl methacrylate) (PBMA) composite particles (PS/PBMA=2/1 by weight) having a heterogeneous structure in which many fine PBMA domains dispersed in a PS matrix near the particle surface were produced by seeded polymerization of n-butyl methacrylate (BMA) of which almost all had been absorbed by 1.8 μm-sized monodispersed PS seed particles utilizing the dynamic swelling method. The morphology was varied by changing the PS/BMA ratio and polymerization temperature. It was concluded that the swelling state of 2 μm-sized BMA-swollen PS particles in the seeded polymerization process is one of the important factors to control the morphology of the composite particles. Received: 27 November 1996 Accepted: 21 March 1997     

Studies of dynamic interactions between a pyrene-labeled polyelectrolyte and an oppositely charged rodlike micelle by a fluorescence quenching technique with use of a hydrophobic quencher

Electrostatic interactions of poly(sodium 2-(acrylamido)-2-methylpropanesulfonate) (PyPAMPS) labeled with pyrene and a rodlike micelle of dimethyloleylamine oxide (DMOAO), an amine oxide type surfactant, mixed with varying mole fractions (Y) of hexadecyltrimethylammonium chloride (CTAC), a cationic surfactant, were investigated by a fluorescence quenching technique using 3,4'-dimethylbenzophenone (DBP), a hydrophobic quencher, that can only reside in the micellar phase. Fluorescence measurements were performed under homogeneous conditions in the region 0Yc, the fluorescence was efficiently quenched by DBP-carrying DMOAO/CTAC mixed micelles, both steady-state and time-dependent fluorescence data indicating that the degree of the quenching and hence the extent of the complex formation increased significantly with increasing Y. Applying a kinetic model to the steady-state and time-dependent fluorescence data, the residence time for PyPAMPS in the polymer-micelle complex was calculated. The residence time was found to depend on both Y and mu, e.g., when Y was increased from 0.01 to 0.03, the residence time increased from 4 to 80 mus at mu=0.05 whereas little or no increase in the residence time was observed in this range of Y at mu=0.20. At this higher ionic strength, the residence time increased only moderately from 3 to 10 mus when Y was increased from 0.01 to 0.09.     

Multidimensional vibrational spectroscopy for tunneling processes in a dissipative environment

Simulating tunneling processes as well as their observation are challenging problems for many areas. In this study, we consider a double-well potential system coupled to a heat bath with a linear-linear (LL) and square-linear (SL) system-bath interactions. The LL interaction leads to longitudinal (T1) and transversal (T2) homogeneous relaxations, whereas the SL interaction leads to the inhomogeneous dephasing (T2*) relaxation in the white noise limit with a rotating wave approximation. We discuss the dynamics of the double-well system under infrared (IR) laser excitations from a Gaussian-Markovian quantum Fokker-Planck equation approach, which was developed by generalizing Kubo's stochastic Liouville equation. Analytical expression of the Green function is obtained for a case of two-state-jump modulation by performing the Fourier-Laplace transformation. We then calculate a two-dimensional infrared signal, which is defined by the four-body correlation function of optical dipole, for various noise correlation time, system-bath coupling parameters, and temperatures. It is shown that the bath-induced vibrational excitation and relaxation dynamics between the tunneling splitting levels can be detected as the isolated off-diagonal peaks in the third-order two-dimensional infrared (2D-IR) spectroscopy for a specific phase matching condition. Furthermore, this spectroscopy also allows us to directly evaluate the rate constants for tunneling reactions, which relates to the coherence between the splitting levels; it can be regarded as a novel technique for measuring chemical reaction rates. We depict the change of reaction rates as a function of system-bath coupling strength and a temperature through the 2D-IR signal.     

Glycosides of Atractylodes lancea

Five sesquiterpenoid glycosides (two guaiane-type glycosides and three eudesmane-type glucosides) and a glucoside of an acetylene derivative were newly isolated from the water-soluble portion of the methanolic extract of Atractylodes lancea rhizome together with 26 known compounds. Their structures were characterized as atractyloside A 14-O-beta-D-fructofuranoside, (1S,4S,5S,7R,10S)-10,11,14-trihydroxyguai-3-one 11-O-beta-D-glucopyranoside, (5R,7R,10S)-isopterocarpolone beta-D-glucopyranoside, cis-atractyloside I, (2R,3R,5R,7R,10S)-atractyloside G 2-O-beta-D-glucopyranoside, and (2E,8E)-2,8-decadiene-4,6-diyne-1,10-diol 1-O-beta-D-glucopyranoside on the basis of chemical and spectroscopic investigation. The presence of six characteristic guaiane-type glucosides in both rhizomes of A. lancea and Atractylodes japonica suggested a close chemotaxonomic relationship between them.     

Oceanic water intrusion into Kagoshima Bay resulting in thermal stratification

Kagoshima Bay is an enclosed bay that has the tendency to undergo eutrophication, and a very important site to describe the behavior of open seawater intrusion. According to the results of the satellite SST (Sea Surface Temperature) image analysis or numerical simulation focused on the warm water intrusion into the bay in winter, a warm water mass originates in the meandering Kuroshio Current and reaches the mouth of the bay making the density flow to act like a semi-geostrophic current that is influenced by the Coriolis effect. However, there is still no information on the oceanic intruding flow during the summer, where it is accompanied by thermal stratification. In this research, satellite remote sensing and numerical simulation were employed to investigate the oceanic water intrusion into Kagoshima Bay during the summer season by using satellite chl-a (chlorophyll-a) images instead of SST. As a result, the distribution of the low-concentration chl-a with the oceanic water intrusion was found to be similar to the intrusion that occurs during the winter season. Furthermore, the numerical simulation was performed under the simple assumption that the thickness of the warm water mass that reaches the southern coast of Kyushu also shows the same tendency as in the winter season. Although the characteristics, such as the intruding speed or intruding pattern, are similar in winter, some features such as the generation of the inflow from the middle layer, showed a different tendency.     

Screening and diagnosis of beta-ureidopropionase deficiency by gas chromatographic/mass spectrometric analysis of urine

Dihydropyrimidine dehydrogenase (DHPDase), dihydropyrimidinase (DHPase) and beta-ureidopropionase (betaUPase) are the enzymes that catalyze the first, second, and third steps of the degradation of pyrimidines, respectively. beta-Ureidopropionate (betaUP) and beta-ureidoisobutyrate (betaUIB) are increased in the urine of patients with betaUPase deficiency. The original case in which betaUPase deficiency was discovered by NMR spectroscopy was an 11-month-old patient who presented with hypotonia and dystonic movement. We detected a second but asymptomatic case during a pilot study of neonatal screening with filter-paper urine, urease pretreatment and gas chromatography/mass spectrometry (GC/MS). The urease pretreatment of urine without fractionation resulted in a high recovery of these polar ureide compounds and allowed the highly sensitive GC/MS detection and diagnosis of betaUPase deficiency. betaUP and betaUIB were identified using GC/MS techniques. In the urine of the neonate with betaUPase deficiency, betaUP and betaUIB were persistently increased. Thymine, 5,6-dihydrothymine and 5,6-dihydrouracil were increased only moderately but significantly. It is known that thymine and uracil increase markedly in DHPDase deficiency, and 5,6-dihydrothymine and 5,6-dihydrouracil increase in DHPase deficiency. Therefore, betaUPase deficiency can be differentially diagnosed from the first and second enzyme deficiencies. Application of this specific and sensitive diagnostic procedure will lead to an understanding of the clinical heterogeneity of betaUPase deficiency. Furthermore, the identification of patients with defects in pyrimidine metabolism will enable doctors to avoid cancer chemotherapy with pyrimidine analogues such as 5-fluorouracil, which could be dangerous for these patients.     

Site-selective formation of N-arylmethylimidazoles and C-arylimines in the reaction of 4,5-diamino-2,1,3-benzothiadiazole with aromatic aldehydes

Regioselective formation of N-arylmethylimidazoles and C-arylimines was found in the reaction of 4,5-diamino-2,1,3-benzothiadiazole with selected aromatic aldehydes. The regiochemistry of the reaction products was confirmed by single crystal X-ray analysis. Gibbs free energy calculation using DFT method at the B3LYP/6-31G(d) level supports the regio-selectivity observed. The 4-imine obtained in the reaction of 4,5-diamino-2,1,3-benzothiadiazole with pyrene-1-carboxaldehyde showed an unusually low magnetic field shift of the imine proton that was reproduced by molecular calculations.