Process Intensification of Living Cationic Polymerization of Isobutylene by a Flow Reaction System

Increasing the reaction temperature of the living cationic polymerization of isobutylene is crucial for industrial production due to the cost of refrigeration. The reaction temperature increase was achieved with an accelerated reaction rate using a flow reaction system. The polymerization conditions, including the flow reactor design, were based on the results of kinetic studies. Utilizing a milli‐scale flow reactor, polyisobutylene, which has a narrow molecular weight distribution, was obtained within a considerably short residence time at a high temperature. Furthermore, it was confirmed that the value of M_w/M_n correlates with the product of the Reynolds number and the angle of collision.     

Correlation between motion of source bender element and feedback signal induced by self-monitoring

Since the introduction of bender element tests to soil testing, the reliability of the estimated travel time has been the most serious problem. The author has previously shown a potential solution whereby removing the response of the bender element subsystem from the whole response could dramatically improve the accuracy of the travel time estimation. In order to lay the foundation for estimating the response of the bender element subsystem, this paper examines the correlation between the displacements of the element and the induced feedback signals by employing a self-monitoring element. The response of the self-monitoring element is modeled as a transfer function involving two internal transfer functions that relate the input signals to the displacements and the displacements to the feedback signals, respectively. Using a laser displacement sensor, the displacements are directly measured through the entire surface and reveal the three-dimensional bending motion of the element oscillating in both longitudinal and width directions. The feedback signals are similar to, but inconsistent with, the tip displacements, and an attempt is made to correct the feedback signals. Finally, a conclusion is given on the potential for estimating the response of the bender element subsystem using the self-monitoring element.     

Combustion synthesis of AlN doped with carbon and oxygen

Carbon-and-oxygen-doped AlN specimens were prepared by combustion synthesis using Al, graphite, and AlN. Graphite addition changed the product color from white to blue. By XRD, the lattice constant increased slightly with increasing carbon content. Blue AlN powder was synthesized with a molar ratio of the diluent AlN of 0.2-0.5 with a fixed graphite content of 0.05. At an AlN molar ratio exceeding 0.6, carbon was not successfully incorporated due to the lower reaction temperature. Calcination at 800°C in air removed residual graphite without changing the crystal structure or product color. Oxygen, nitrogen, and carbon analyses revealed that blue AlN powders contained 0.45-0.54 mass% carbon and 1.4-1.6 mass% oxygen, while the undoped AlN contained 0.021 mass% carbon and 0.94 mass% oxygen. The origin of the white-to-blue color change was investigated via reflection measurements. Blue AlN exhibits an absorption peak at 634 nm (1.96 eV). From first-principles electronic structure calculations, the C-doped AlN and carbon-and-oxygen-doped AlN with a 1:1 ratio could be classified as p-type, whereas the O-doped AlN and 1:3 carbon-and-oxygen-doped AlN were n-type. One reason for the absorption peak at 634 nm may be a transition from the conduction band to an upper unoccupied state. These results suggest the possible control of optical and electronic properties of AlN via carbon-and-oxygen doping.     

A Bayesian propensity score adjustment for latent variable modeling and MCMC algorithm

The estimation of the differences among groups in observational studies is frequently inaccurate owing to a bias caused by differences in the distributions of covariates. In order to estimate the average treatment effects when the treatment variable is binary, Rosenbaum and Rubin [1983. The central role of the propensity score in observational studies for causal effects. Biometrika 70, 41-55] proposed an adjustment method for pre-treatment variables using propensity scores. Imbens [2000. The role of the propensity score in estimating dose-response functions. Biometrika 87, 706-710] extended the propensity score methodology for estimation of average treatment effects with multivalued treatments.However, these studies focused only on estimating the marginal mean structure. In many substantive sciences such as the biological and social sciences, a general estimation method is required to deal with more complex analyses other than regression, such as testing group differences on latent variables. For latent variable models, the EM algorithm or the traditional Monte Carlo methods are necessary. However, in propensity score adjustment, these methods cannot be used because the full distribution is not specified.In this paper, we propose a quasi-Bayesian estimation method for general parametric models that integrate out the distributions of covariates using propensity scores. Although the proposed Bayes estimates are shown to be consistent, they can be calculated by existing Markov chain Monte Carlo methods such as Gibbs sampler. The proposed method is useful to estimate parameters in latent variable models, while the previous methods were unable to provide valid estimates for complex models such as latent variable models.We also illustrated the procedure using the data obtained from the US National Longitudinal Survey of Children and Youth (NLSY1979-2002) for estimating the effect of maternal smoking during pregnancy on the development of the child's cognitive functioning.     

Activity measurement of the constituents in molten Fe–B and Fe–B–C alloys

The distribution ratios of Fe and B between molten Fe–B alloy and molten Ag were measured at temperatures between 1573 and 1923 K. Also, distribution ratios of Fe and B between molten Fe–B–C_satd. alloys and molten Ag were measured at 1873 K. It was found that the excess Gibbs free energy of mixing in molten Fe–B and Fe–B–C alloys can be expressed by utilizing the Redlich–Kister polynomial. The activity curves of the elements in molten Fe–B alloy and Fe–B–C alloy were estimated.     

Effects of high molecular weight component on crystallization of polyethylene under shear flow

Crystallization of polyethylene (PE) blends of low and high molecular weight components under shear flow was studied using time-resolved depolarized light scattering (DPLS), focusing on effects of the high molecular weight component on the shish-kebab structure formation. Anisotropic two-dimensional scattering pattern due to shish-like structure formation was observed above a certain concentration of the high molecular weight PE. The threshold was about 2.5-3 times larger than the chain overlap concentration, suggesting an important role of entanglements of the high molecular weight component. On the basis of these results a gel-spinning-like mechanism for the shish-like structure formation has been proposed. The DPLS results also implied that the shish-like structure was mainly formed from the high molecular weight PE. This was confirmed by small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) measurements on an elongated PE blend of low molecular weight deuterated PE and high molecular weight hydrogenated PE (3 wt%).     

STM tunneling spectroscopy on high Tc superconductors

STM tunneling spectroscopy has been performed on the bulk single crystals of BiSrCaCuO (BSCCO) and the epitaxial thin films of YBaCuO (YBCO) at cryogenic temperatures. The STM images and tunneling spectra observed on the (001) surfaces can be classified into three cases; 1) Atomic image is visible. However, the tunneling spectrum shows semiconducting or smeared superconducting gap structures, depending on the tip-sample distance. 2) Clear atomic image can not be obtained. But, the tunneling spectrum shows flat bottom region with quite low zero bias conductance. 3) Tunneling spectra demonstrate gapless behavior, independent of the tip-sample separation. These observations support the quasi-2D electronic picture in whichs-wave like 2D superconducting layers are coupled with each other through the Josephson effect.     

High-performance carbon counter electrode for dye-sensitized solar cells

Here, we reported that a new carbon electrode prepared with an activated carbon was superior to a Pt sputtered electrode as the counter electrode of dye-sensitized solar cells. The photovoltaic performance was largely influenced by the roughness factor of carbon electrode. The open-circuit voltage increased by about 60 mV using the carbon counter electrode compared to the Pt counter electrode because of positive shift of the formal potential for I₃⁻/I⁻ couple.     

Combined pars plana vitrectomy, lens removal and intraocular lens implantation for complications of diabetic retinopathy. Surgical results in 120 cases

We performed combined vitrectomy, lens removal and posterior chamber intraocular lens implantation for proliferative diabetic retinopathy in 120 eyes of 101 patients. Follow-up periods ranged from 3 to 63 months, with a mean of 17 months. Three lens removal methods were used: extracapsular cataract extraction (14 eyes), phacoemulsification and aspiration (49 eyes), and pars plana phacoemulsification (57 eyes). Preoperative rubeosis iridis or neovascular glaucoma was found in 21 eyes. Gas or temporary silicone oil tamponade was employed in 32 eyes. Surgical results were good, and the postoperative vision was finger counts or below only in 13 eyes. Thus the combined surgery proved to have no serious problems. Our results indicate two important points. (1) It is best to chose either of the following two methods for the lens surgery: phacoemulsification with continuous circular capsulorhexis, self sealing sclerocorneal incision, and in-the-bag fixation of the posterior chamber lens, or pars plana phacoemulsification leaving the anterior capsule, rub off and aspirating the lens epithelial cells, continuous circular capsulorhexis, and posterior chamber lens implantation in front of the anterior capsule from a self-sealing sclerocorneal wound. (2) It is mandatory to do complete vitrectomy and cut out the vitreous gels incarcerated in the sclerotomy site.     

Oligosaccharide structures formed during the hydrolysis of lactose by Aspergillus oryzae β-galactosidase

Di-, tri-, tetra-, penta- and hexasaccharides were formed during the hydrolysis of lactose by transgalactosylation reaction of Aspergillus oryzae β-galactosidase. In this study the isolation and characterization of the major constituents of tri-, tetra- and pentasaccharides are described. The structure elucidation of 3 tri-, 2 tetra- and 1 pentasaccharides was carried out by methylation analysis, mass spectrometry and ¹³C-nmr spectrometry. The trisaccharides are $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 3)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}\text{(3′-}\text{galactosyl-lactose}\text{)}$, $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}\text{(6′-}\text{galactosyl-lactose}\text{)}$ and $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-O-[β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)]-}\text{d}\text{-}\text{glucose}\text{(4,6-}\text{digalactosyl-glucose}\text{)}$. Tetrasaccharides are $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}$ and $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 3)}$ [or $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 3)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)]-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}$. Pentasaccharide is $\text{O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 6)-O-β-}\text{d}\text{-}\text{galactopyranosyl}\text{-(1 → 4)-}\text{d}\text{-}\text{glucose}$.