Evaluation of mass-produced commercial LiTaO3 single crystals using the LFB ultrasonic material characterization system

A mass-production line of lithium tantalate (LiTaO3) crystals with a maximum charge number of 60 for surface acoustic wave (SAW) devices was evaluated with the line-focus-beam (LFB) ultrasonic material characterization system. Some serious problems associated with chemical compositions were observed and resolved by measuring the velocities of Rayleigh-type leaky surface acoustic waves (LSAWs), VLSAW, for two groups of LiTaO3 wafers: 21 36 degrees Y X-LiTaO3 wafers selected randomly from crystal ingots grown with different charge numbers in different furnaces, and 14 42 degrees Y X-LiTaO3 wafers obtained at the top, middle, and bottom parts from 5 crystals selected from 39 crystals grown successively in the same furnace and crucible. Using the measured VLSAW and the predetermined relationship between VLSAW and Li2O concentrations, M(Li2O), we estimated the average M(Li2O) controlled in the current mass-production line to be about 48.77 mol% with a maximum difference of 0.75 mol%. The composition for each crystal ingot increased linearly about 0.04 mol% from the top to the bottom, and no dependence on the charge number was observed, as the melt composition used for the mass production was controlled through Curie temperature (TC) measurements. A nearly true congruent composition of 48.49 Li2O-mol% was obtained through the precise VLSAW data for the 42 degrees Y X-LiTaO3 wafers, that was about 0.3 mol% less than the melt composition in the production line. It was also pointed out that the TC measurement conditions, including room temperatures surrounding the measurement systems, should be re-examined for reliable production control. A guideline for more efficient mass production of the crystals has been established concerning the true congruent composition as the starting material.     

On-column derivatization using redox activity of porous graphitic carbon stationary phase: an approach to enhancement of separation selectivity of liquid chromatography

A new on-column derivatization method based on the redox activity of porous graphitic carbon (PGC) packing materials was presented for enhancement of separation selectivity of HPLC. Two PGC packing materials were used as the solid redox agents as well as the stationary phase, and their redox activities were investigated using trans-1,2-diaminocyclohexanetetraacetate (DCTA) complexes of some metal ions as probe compounds. It was found that the redox property of PGC was modified by treating them with a solution containing a reducing agent, sodium sulfite or hydroxylammonium chloride. The original PGC packings oxidized Co(II)-DCTA to Co(III)-DCTA during elution, while the PGC treated with a reducing agent showed reduction activity converting Co(III)-DCTA to Co(II)-DCTA. These two cobalt complexes do not form their individual chromatographic zones but migrate as a single zone of their mixture on the PGC column contrary to the chromatographic behavior on a C18 bonded silica, on which Co(II)-DCTA and Co(III)-DCTA can be separated. Treatment of the PGC column with a reducing agent solution transforms the oxidative activity of the original PGC packing to a reductive one from the upper part of the column, so that the retention time of the cobalt complex can be controlled by changing the volume of the reducing agent solution to be used for treatment of the PGC column. The selective separation and determination of cobalt in a reference manganese nodule sample by the developed method was demonstrated.     

InP-based IC technologies

The research and development of InP-based devices and integrated circuits (ICs) are driven by applications in broadband optical-fiber communications systems and microwave and millimeter-wave wireless systems. This paper describes recent progress on our InP-based device and IC technologies for 40-Gbit/s optical fiber communications and 10-Gbit/s class millimeter-wave wireless links. Device performance requirements for future 100-Gbit/s class ICs are then discussed along with our device technology roadmap. We also describe our latest 100-Gbit/s class optical fiber communication IC results.     

Fatty Acid Amides,Previously Identified in Caterpillars,Found in the Cricket <Emphasis Type="Italic">Teleogryllus taiwanemma</Emphasis> and Fruit Fly <Emphasis Type="Italic">Drosophila melanogaster</Emphasis> Larvae

Fatty acid amides (FAAs) are known elicitors that induce plants to release volatile compounds that, in turn, attract foraging parasitoids. Since the discovery of volicitin [N-(17-hydroxylinolenoyl)-l-glutamine] in the regurgitant of larval Spodoptera exigua, a series of related FAAs have been identified in several other species of lepidopteran caterpillars. We screened 13 non-lepidopteran insects for the presence of FAAs and found that these compounds were present in adults of two closely related cricket species, Teleogryllus taiwanemma and T. emma (Orthoptera: Gryllidae), and larvae of the fruit fly, Drosophila melanogaster (Diptera: Drosophilidae). When analyzed by liquid chromatography/mass spectrometry-ion trap-time-of-flight (LCMS-IT-TOF), the gut contents of both crickets had nearly identical FAA composition, the major FAAs comprising N-linolenoyl-l-glutamic acid and N-linoleoyl-l-glutamic acid. There were also two previously uncharacterized FAAs that were thought to be hydroxylated derivatives of these glutamic acid conjugates, based on their observed fragmentation patterns. In addition to these four FAAs containing glutamic acid, N-linolenoyl-l-glutamine and a small amount of volicitin were detected. In D. melanogaster, N-linolenoyl-l-glutamic acid and N-linoleoyl-l-glutamic acid were the major FAAs found in larval extracts, while hydroxylated glutamic acid conjugates, volicitin and N-linolenoyl-l-glutamine, were detected as trace components. Although these FAAs were not found in ten of the insects studied here, their identification in two additional orders of insects suggests that FAAs are more common than previously reported and may have physiological roles in a wide range of insects besides caterpillars.     

CO2 Sensing Property of CuO-BaTiO3 Mixed Oxide Film Prepared by Self-Assembled Multibilayer Film as a Precursor

Preparation of CuO-BaTiO₃ mixed oxide thin film by the decomposition of a self-assembled multibilayer film as a molecular template was investigated in this study. Furthermore, CO₂ sensing property of the resultant thin film was investigated as a capacitive type sensor. The self-assembled bilayer film of few 1000 layers thickness can be obtained easily by casting an aqueous suspension consisting of dimethyldihexadecylammoiun bromide (DC1-16), Cu(ClO₄)₂, Ba(TiO(C₂H₄)₂), 2,6-dimetyle-3,5heptadione (DHP), and polyvinyl alcohol. Divalent copper ion (Cu²⁺)) which is associated with 2 DHP molecules was incorporated into the molecular bilayer film and BaTiO₃ precursor exists at the interspace of molecular bilayer film by coordinating with polyvinyl alcohol. Upquenching the organic-inorganic film at 1173 K leads to the uniform film of CuO-BaTiO₃ oxide mixture. Although operating temperature shifted to higher temperature, the resultant film exhibits the capacitance change upon exposure to CO₂. Consequently, it is concluded that the mixed oxide film of CuO-BaTiO₃ prepared by the decomposition of multibilayer film was also an appropriate capacitive type CO₂ sensor.     

Synthesis of a Potent G‐Quadruplex‐Binding Macrocyclic Heptaoxazole

A novel G‐quadruplex binder , L1H1‐7OTD (shown in color by atom type), was developed. This macrocyclic heptaoxazole potently and selectively stabilizes telomeric DNA in an intramolecular antiparallel G‐quadruplex conformation. L1H1‐7OTD shows selective cytotoxicity toward HeLa cells, a telomerase‐positive cell line.

     

New polylactide-layered silicate nanocomposites. 2. Concurrent improvements of material properties, biodegradability and melt rheology

Our continuing research on the preparation, characterization, materials properties, and biodegradability of polylactide (PLA)-layered silicate nanocomposites has yielded results for PLA-montmorillonite nanocomposites. Montmorillonite modified with trimethyl octadecylammonium cation was used as an organically modified layered silicate for the nanocomposites preparation. The internal structure of the nanocomposites in the nanometer range has been established by using wide-angle X-ray diffraction and transmission electron microscope analyses. All the nanocomposites exhibited superior improvement of practical materials properties such as storage modulus, flexural modulus, flexural strength, heat distortion temperature, and gas barrier property as compared to that of neat PLA. The biodegradability of neat PLA and a representative nanocomposite was also studied under compost, and the rate of biodegradation of neat PLA significantly increased after nanocomposites preparation. The melt rheology of neat PLA and various PLACNs was also studied.     

Reaction of sodium perborate with a chlorinated cyclic hindered amine (N-chloro-4-hydroxy-2,2,6,6-tetramethylpiperidine) II. Activating effects and related characteristics in practical fabric bleaching

A synergetic bleaching activation phenomenon of the chlorinated cyclic hindered amine, N-chloro-4-hydroxy-2,2,6,6-tetramethylpiperidine (TMP-Cl) on sodium perborate (PB) was examined under some practically applicable bleaching procedures. By combining TMP-Cl with PB, the bleaching effect toward black tea, fruit juices and other stains was enhanced synergetically, achieving an efficiency similar to that of the well-known tetraacetylethylenediamine/PB system. However, behavior observed in the TMP-Cl/PB system, such as high bleaching efficiency in an alkaline range, superior durability for repeated bleaching, less discoloration of cloth that contains reactive dyes and no influence on the activity of an enzyme, was favorable for a bleaching component of heavy-duty detergents.     

Formation of alkoxy-derived 3Al2O3 · 2GeO2

Germanium-mullite (3Al₂O₃·2GeO₂) is formed directly as a single phase at lower temperatures from amorphous material with 50–66.7 mole% Al₂O₃ prepared by the alkoxy-method. The kinetic data of the 3Al₂O₃·GeO₂ crystallization with 50 and 60 mole% Al₂O₃ are represented by different solid-state equations. The difference of the crystallization mechanism is possibly explained in terms of the morphology of the 3Al₂O₃·GeO₂ particles.     

The sensing-based adaptive risk mitigation of leaking hydrogen in a partially open space

This study performs the numerical simulation of hydrogen dispersion in a partially open space. The space under investigation measures 2.9 m × 1.22 m × 0.74 m and a leak flow rate of 2 standard cubic feet per minute is assumed. The effects of various roof vent positions and their areas on the ability to recognize the dispersion and accumulation of hydrogen, and its natural ventilation, are shown and discussed. Based on the results, this paper proposes an innovative approach to the sensing-based adaptive risk mitigation control of hydrogen dispersion and accumulation in a partially open space. By adaptively opening roof vents near the leak source, and closing other neighboring roof vents, concentrated hydrogen is exhausted rapidly and efficiently. It is also shown that cases exist where sufficient area of the proposed adaptive roof vent can be determined by the finite-time sensing of hydrogen concentration near the roof. The effects of the delay time of a sensor, and a method to cancel these effects, are also discussed.