Determination of assigned configurational parameters for cross propagation in radical copolymerization of methyl methacrylate and trityl methacrylate

Summary Copolymer of methyl methacrylate-d₈(M₁) with a small amount of trityl methacrylate(M₂) was radically prepared in tetrahydrofuran and converted into the copolymer of methyl methacrylate-d₈ with a small amount of undeuterated methyl methacrylate by the selective hydrolysis of the trityl group and subsequent methylation with diazomethane. From the ¹H NMR spectrum of the derived copolymer the assigned coisotactic parameters ₁₂ and ₂₁ were determined to be 0.14 and 0.61, respectively. This may be the first example of the unequivocal determination of assigned configurational parameters in cross propagation for copolymerization.     

All-optical wavelength conversion in a GaInAsP/InP optical gate loaded with a Bragg reflector

All-optical wavelength conversion employing a GaInAsP/InP nonlinear distributed-feedback waveguide switch is investigated. The device has the advantages of simple structure, compactness, polarity-noninverted operation, and feasibility of integration with other photonic devices such as semiconductor optical amplifier and modulators. We show that the device exhibits constant conversion efficiency around -9.2 dB in a signal-wavelength range of 1530-1560 nm. Furthermore, this device can potentially be made polarization independent.     

Chemicofunctional membrane for integrated chemical processes on a microchip

Here we report a design and synthesis of a chemically functional polymer membrane by an interfacial polycondensation reaction and multilayer flow inside a microchannel. Single and parallel dual-membrane structures are successfully prepared by using organic/aqueous two-layer flow and organic/aqueous/organic three-layer flow inside the microchannel followed by an interfacial polycondensation reaction. By using the inner-channel membrane, permeation of ammonia species through the inner-channel membrane is successfully achieved. Furthermore, horseradish peroxidase is immobilized on one side of the membrane surface to integrate the chemical transform function onto the inner-channel membrane. Here substrate permeation through the membrane and subsequent chemical transformation at the membrane surface are realized. The polymer membrane prepared inside the microchannel has an important role in ensuring stable contact of different phases such as gas/liquid or liquid/ liquid and the permeation of chemical species through the membrane. Furthermore, membrane surface modification chemistry allows chemical transformation of permeated chemical species. These methods are expected to lead to development of complicated and sophisticated chemical systems involving membrane permeation and chemical reactions.     

Inverse scattering for a three-dimensional object in the time domain

An iterative inverse-scattering approach to reconstruction of electrical parameter distributions of a three-dimensional object by using time-domain field data is presented. The approach is the extension of the forward-backward time-stepping algorithm previously proposed for a two-dimensional object. Numerical examples of simulation data are given to assess the effectiveness of the proposed approach.     

Roasting effects on the distribution of tocopherols and phospholipids within each structural part and section of soybeans

To clarify the effects of microwave roasting on the distribution of tocopherols and FA of phospholipids within soybeans, whole soybeans (Glycine max) were treated by microwave and further evaluted as compared to a raw sample. Tocopherol homologs, measured using HPLC, and phospholipid profiles, quantified with GC, were determined in the seed coat, the embryonic axis, and selections of cotyledons separated from three cultivars. The tocopherols were predominantly detected in the axis, followed by the cotyledons, and then very little in the coat. As much as 25% of the individual tocopherols originally present in the coat were lost at 12 min of roasting, whereas <25% was lost in the cotyledons and the axis after 20 min of roasting. The greatest rate of phospholipid loss (P<0.05) was observed in PE, followed by PC and PI, and their changing patterns were more pronounced in the coat than in the cotyledons or the axis. Thus, tocopherol content and phospholipid profiles change with microwave roasting according to tissue.     

Recombination of Spin Polarized Atomic Hydrogen Adsorbed on a Dilute 3He-4He Mixture

We have been searching for two-dimensional (2-D) superfluidity of spin-polarized atomic hydrogen (H) adsorbed on liquid helium surface. We have investigated H adsorbed on ³ He- ⁴ He mixtures instead of pure ⁴ He because the thermal coupling of H to the mixtures is stronger than ⁴ He. ESR at 129 GHz was carried out to detect H at 4.5 T by using the Fabri-Perot confocal cavity with the cold spot located at the confocal point and thus the 2-D H signal was effectively detected. We investigated the two-body bulk and surface recombination processes of H on a 3% ³ He ³ He- ⁴ He mixture film. From the analysis of the surface recombination process, we found the adsorption energy of H was a 0.6 K for the mixture film in the temperature range between 120 mK and 250 mK, greater than the 0.3–0.4 K found previously for pure ³ He and a 67% ³ He ³ He- ⁴ He mixture.     

Possible 3He Boltzmann Gas Formed on Three-Dimensional Nanopores Preplated with 4He

We have measured the heat capacity of ³He adsorbed on three-dimensionally connected nanopores, 2.7 nm in diameter, preplated with about 1.3 atomic layers of ⁴He. At low coverages of ³He, the ³He heat capacity is roughly constant at the measured temperatures between 0.1 and 1 K. Its molar heat capacity is on the order of the gas constant R, between 1.1R and 1.8R. This suggests a Boltzmann gas state of the adsorbed ³He. At high coverages, the heat capacity is likely approaching linear in T at low temperatures, which suggests a degenerate state at further lower temperatures.     

Optical Burst Switching Router With 40-,10-Gb/s Bit-Rate Transparent Contention Resolution

We report a bit-rate transparent optical burst switching (OBS) router prototype using a fast 5 times 5 PLZT [(Pb,La)(Zr,Ti)O₃ ] optical matrix switch. Dynamic switching in a two-wavelength, 2 times 2 OBS switch is demonstrated. Contention resolution using a tunable Mach-Zehnder interferometer wavelength converter for both 40- and 10-Gb/s bursts is demonstrated for the first time. Error-free operation was achieved for both bit rates under the same settings, as required in autonomous networks     

Piezoelectric properties in (K0.5Bi0.5)TiO3-(Na0.5Bi0.5)TiO3-BaTiO3 lead-free ceramics.

Lead-free piezoelectric ceramics with compositions around the morphotropic phase boundary (MPB) x(Na0.5Bi0.5)TiO3-y(K0.5Bi0.5)TiO3-zBaTiO3 [x + y + z = 1; y:z = 2:1] were synthesized using conventional, solid-state processing. Dielectric maximum temperatures of 280 degrees C and 262 degrees C were found for tetragonal 0.79(Na0.5Bi0.5)TiO3-0.14(K0.5Bi0.5)TiO3-0.07BaTiO3 (BNBK79) and MPB composition 0.88(Na0.5Bi0.5)TiO3-0.08(K0.5Bi0.5)TiO3-0.04BaTiO3 (BNBK88), with depolarization temperatures of 224 degrees C and 162 degrees C, respectively. Piezoelectric coefficients d33 were found to be 135 pC/N and 170 pC/N for BNBK79 and BNBK88, and the piezoelectric d31 was determined to be -37 pC/N and -51 pC/N, demonstrating strong anisotropy. Coercive field values were found to be 37 kV/cm and 29 kV/cm for BNBK79 and BNBK88, respectively. The remanent polarization of BNBK88 (approximately 40 microC/cm2) was larger than that of BNBK79 (approximately 29 microC/cm2). The piezoelectric, electromechanical, and high-field strain behaviors also were studied as a function of temperature and discussed.