Freezing step controls the mannitol phase composition heterogeneity

Freeze-dried samples were prepared from D-mannitol solution by selected freezing conditions. Crystalline structures of prepared samples were determined by XRD analysis, and distributions of the various crystal structures of mannitol were obtained for each sample. It was found that the amount of each polymorph was quite well correlated to the freezing conditions, namely the ice crystal nucleation temperature and the cooling rate. In case of samples prepared at fast cooling rates, the samples where the ice crystals nucleated at higher temperature contained much more stable form than the samples nucleated at lower temperature. Besides, the samples prepared at slow cooling rates predominantly contained stable crystalline forms despite of the variation of nucleation temperatures. Moreover, the experimental results also indicated that the various polymorphs were also distributed vertically through the sample along the direction of the heat flux during freezing. The tendency of the polymorph distribution through the freeze-dried cake was also elucidated by using the simulated temperature profiles during freezing. Thus, the profiles of mannitol polymorphs after the freezing derived from the temperature distributions could predict the global tendency of polymorphism behaviour, and, consequently, would be useful to achieve quality control of freeze-dried formulations.     

Synthesis of proton conductive membranes based on inorganic–organic hybrid structure bound with phosphonic acid

Proton conductive inorganic–organic hybrid membranes were synthesized from styrene derivatives of alkoxysilane and ethyl 2-[3-(dihydroxyphosphonyl)-2-oxopropyl] acrylate (EPA) through copolymerization followed by sol–gel reaction. Self-standing, homogeneous and transparent hybrid membranes with chemically bound phosphonic acid groups were synthesized. FT-IR analysis exhibited the hybrid membranes included phosphonic acid groups. ¹³C and ²⁹Si NMR studies indicated that alkoxysilyl functionalized styrene derivatives were not only copolymerized with EPA but also condensed yielding Si–O–Si linkages by sol–gel reaction. TG–DTA analysis revealed that these membranes were thermally stable up to 200 °C in dry O₂. The proton conductivities of the hybrid membranes increased with phosphonic acid content and temperature. The P/Si ratio of the membrane was dependent on the number of alkoxy group in the starting alkoxysilane. The hybrid membrane from (dimethylmethoxysilylmethyl)styrene (DMMSMS(M))/EPA = 1/6 revealed proton conductivities of 6.3 × 10⁻³ and 2.4 × 10⁻⁴ S cm⁻¹ at 68.0% relative humidity and 18.8% relative humidity, respectively, at 140 °C.     

Comparison of Klinkenberg-corrected gas permeability and water permeability in sedimentary rocks

We measured intrinsic permeability of sedimentary rocks from the western foothills of Taiwan by using nitrogen gas and distilled water as pore fluids in effective-pressure cycling tests at room temperature. The observed difference in gas and water permeabilities was analyzed in view of the Klinkenberg effect. This effect is due to the slip flow of gases at pore walls, which enhances gas flow when pore sizes are very small. Our experimental results showed that (1) gas permeability was larger than water permeability by several times to one order of magnitude, (2) gas permeability increased with increasing pore pressure, and (3) water permeability increased slightly as the pore-pressure gradient across the specimen increased. Results (1) and (2) can be explained quantitatively by an empirical power law in relation to the Klinkenberg constant b that is applicable in low permeable range. This correlation enables us to estimate water permeability from gas permeability. The Klinkenberg effect is important when permeability is lower than 10^?18 m² and at low pore-pressure differentials, and correction for the effect is essential to estimate water permeability from gas permeability measurement data. A simplified Bingham flow model for water can partially explain the trend of result (3), although non-Darcy flow behavior or inertial forces of water–rock interaction are needed to account for the observed deviation from Darcy's law.     

In-fibre LP11–LP21 mode conversion using force-induced long-period fibre gratings with polarization controllers

ABSTRACT

Mode conversion between higher-order modes is attained in a step-index four mode fibre using an in-line polarization controller followed by a force-induced long period fibre grating. By adjusting the field orientation of the LP₁₁ mode to the antisymmetric fibre grating, the LP₁₁ mode is converted to the LP₂₁ mode with a spatially periodic force of 50 N along the fibre length of 50?mm. The mode conversion is evaluated by observing the far-field and near-field patterns of the fibre output and by comparing the transmitted optical power with and without the additional two-mode fibre. The phase-matching grating period is required of the accuracy of roughly ±5?μm and the radiation loss during the mode conversion is as low as 0.01?dB.     

Response of Predatory Insect Scolothrips takahashii Toward Herbivore-Induced Plant Volatiles Under Laboratory and Field Conditions

We studied the response of a predatory thrips, Scolothrips takahashii, towards herbivore-induced plant volatiles emitted by Lima bean plants infested by two-spotted spider mites Tetranychus urticae (green form). Tests were conducted with a Y-tube olfactometer in the laboratory and with traps under field conditions. The odor of artificially damaged and uninfested Lima bean leaves was not more attractive than clean air in the Y-tube olfactometer. The predatory insects showed a greater preference for Lima bean leaves infested by the two-spotted spider mites than for either clean air or uninfested bean leaves. They showed the same preference towards infested leaves from which all spider mites and their visible products had been removed. Neither the spider mites themselves nor their products attracted the predators. In a satsuma mandarin grove, two traps with infested Lima bean plants as an odor source attracted 42 adult S. takahashii in 55 days, whereas no S. takahashii were trapped in two control traps with uninfested Lima bean plants during the same period. No S. takahashii were found during this period in the vicinity of either the sample traps or the control traps (5-m radius of each trap). These data showed that S. takahashii use herbivore-induced plant volatiles in their foraging behavior in natural ecosystems.     

Application and development of synthetic polymer membranes. VI. Pervaporation of aqueous ethanol solution through quaternized poly[3-(N′,N′-dimethyl) aminopropylacrylamide-co-acrylonitrile] membranes

Membranes obtained from polymers, quaternized poly[3-(N′,N′-dimethyl) aminopropylacrylamide-co-acrylonitrile]s, showed selective separation of water from aqueous ethanol solution by pervaporation. The separation factor toward water reached over 15,000. Membrane performance showed a good correlation to membrane polarity. Differential scanning calorimetric melting endotherms of the water-swollen membranes were studied to clarify the state of water in the membranes. The results suggested that there are two states of water in the membrane: bound and free. The higher the fraction of bound water in the membrane, clearly, the more preferentially was water permeated.     

Ag nanorod arrays tailored for surface-enhanced Raman imaging in the near-infrared region

Using a dynamic oblique angle deposition technique, we demonstrate the direct formation of Ag nanorods with quasi-parallel major axes on a template layer of oxide having a strongly anisotropic surface morphology. The optical properties of the nanorods are tuned by varying the deposition conditions without any pre-?or post-treatment, and the resulting Ag nanorod arrays exhibit high surface-enhanced Raman scattering (SERS) activity. In addition to high macroscopic uniformity over a large area, our nanorod arrays contain a high density of isolated nanorods. Using the optimum Ag nanorod arrays, the SERS imaging of the microdroplets of a rhodamine 6G solution is successfully demonstrated. The space resolution of the imaging is of the order of at least a few μm. These features are suitable for the SERS imaging of biomaterials.     

On-line measurement of orientation development in the high-speed melt spinning process

On-line measurement of birefringence was performed in the high-speed melt spinning process of poly(ethylene terephthalate) using an apparatus that incorporates a rotating polarizer for the measurement of the optical retardation of running filament. Particular attention was paid to the detailed measurements in the vicinity of neck-like deformation. Through the measurement at the take-up velocity of 5 km/min, development of birefringence under the strain rate up to about 1 ms^?1 was investigated. To analyze the relation between applied stress and birefringence, tension and temperature profiles of the spin-line were calculated based on the experimentally obtained diameter profiles. Even though the strain rate is extremely high, a linear relationship between birefringence and a parameter calculated by dividing stress by temperature was confirmed to hold up to birefringence and stress/temperature values of about 0.017 and 10 kPa/K, respectively.     

Processing of Oriented K(Ta,Nb)O3 Films Using Chemical Solution Deposition

K(Ta,Nb)O₃ (KTN) thin films have been prepared by the chemical solution deposition method. KTN precursors consisted of a uniform mixture of K[Ta(OC₂H₅)₆] and K[Nb(OC₂H₅)₆] with interaction at the molecular level. Perovskite KTN thin films with the desired composition (Ta/Nb = 65/35, 50/50, and 35/65) were synthesized from the precursor solutions by the dip coating method. KTN thin films with (100) preferred orientation were successfully synthesized on MgO(100) and Pt(100)/MgO(100) substrates. X-ray pole figure measurements showed that grains of KTN films had a prominent three-dimensional regularity on MgO(100) and Pt(100)/MgO(100) surfaces. The Curie temperatures of KTN films decreased with increasing Ta/Nb ratio. Typical P-E hysteresis loops were observed for KTN thin films of three compositions on Pt(100)/MgO(100) substrates. The values of remanent polarization ( P _r) of KTN films increased as the Ta/Nb ratio changed from 65/35 to 35/65.     

Influences of gas density depletion on high‐pressure,pulsed‐glow discharge

High‐pressure, pulsed glow discharge has been studied for the excitation discharge in TEA gas lasers. Various instabilities occur in the subsequent discharge, which induce the arc and collapse for the highly repetitive operation. In this paper, the influences of the gas density depletion on the high‐pressure, pulsed glow discharge have been investigated, eliminating the other instabilities such as shock waves, residual ions, discharge products, and electrode heating. The gas density depletion was produced by utilizing a subsonic flow between the curved electrodes. The comparison has been made on the discharge occurring in the presence of the gas density depletion with that by the double‐pulse experiment in a stable gas. The big gas density nonuniformity tends to cause the arc without the shocks, ions, discharge products, and electrode heating. The transition from glow to arc discharge discontinuously occurs with respect to the gas density depletion. On the other hand, the second discharge in the double‐pulse experiment becomes an arc in much smaller gas density nonuniformity, and the transition from glow to arc occurs gradually. The arc discharge might be driven by some factors other than the gas density depletion. © 2000 Scripta Technica, Electr Eng Jpn, 130(4): 9–16, 2000