Radial Fourier multipliers in high dimensions

Given a fixed p≠2, we prove a simple and effective characterization of all radial multipliers of FL^p( \mathbbR^d ) \mathcal{F}{L^p}\left( {{\mathbb{R}^d}} \right) , provided that the dimension d is sufficiently large. The method also yields new L ^q space-time regularity results for solutions of the wave equation in high dimensions.     

Influence of the Ga addition on optical properties of Pr in Ge–Sb–Se glasses

Absorption and emission spectra for the ³H₄↔(³F₂, ³H₆) transition of Pr³⁺ ions embedded in Ge–Sb–Se glasses turned out to change systematically upon the introduction of a small amout of Ga. Clear blueshift of the absorption peak wavelengths together with the decrease of absorption cross-section was evident in these glasses containing Ga. We believe that the Ga addition into the conventional covalent selenide glasses makes chemical bonds between rare earth atoms and Se atoms more ionic due to preferential location of the GaSe₄ tetrahedra at the second coordination shell of a rare earth atom. Taking into consideration the hypersensitive nature of the Pr³⁺: ³H₄↔³F₂ transition, the observed blueshift may manifest the enhanced ionicity of the chemical bonds between Pr and Se in the current Ga-containing glasses.     

Compositional dependences on the mechanism of upconversion in Nd3+/Tm3+ co-doped chalcohalide glasses

Mechanisms of the compositional dependence of blue emission from Nd³⁺/Tm³⁺ co-doped Ge–Ga–S–CsBr chalcohalide glasses were investigated. The blue upconversion emissions (centered at 475 nm) due to the Tm³⁺: ¹G₄ → ³H₆ transition decreased as the CsBr/Ga ratio in glasses while the other upconversion emissions from the Nd³⁺ ions increased. Changes in the local environment of rare-earth ions incurred by the CsBr addition significantly increased the excited state absorption within Nd³⁺ ions. This resulted in the decrease in the Nd³⁺ → Tm³⁺ energy transfer rates that led to the large decrease in blue upconversion emission.     

Thermal decomposition mechanism of Ba(DPM)2

We have investigated the thermal decomposition behavior of Ba(DPM)₂ using thermogravimetry (TG), mass spectrometry (MS), ultraviolet (UV) absorption and in-situ Fourier transform infrared (FTIR) spectroscopy. FTIR has been used particularly for direct monitoring of the bond dissociation order in the metal complex by thermal treatment in either N₂ or O₂. TG analysis shows that the ambient gas has a significant effect on the weight loss patterns of Ba(DPM)₂. The chemical bonds of Ba(DPM)₂ begin to decompose at low temperatures below 50 °C and are sequentially dissociated when the temperature is raised. The C-C(CH₃)₃ and the Ba-O bonds are decomposed most easily at low temperatures, followed by the C-H bond, but the stable C-C and C-O bonds do not dissociate until the total complex is gasified. The decomposition sequence of the chemical bonds in Ba(DPM)₂ is similar to that of Sr(DPM)₂ but differs from that of Ti(O-iPr)₂(DPM)₂ which is decomposed in the sequence of C(CH₃)₃ > C-H and C-O > Ti-O. The major difference in the decomposition sequence between Ba and Ti complexes can be seen to derive from the intrinsic character of the individual metal-oxygen bond as observed by UV spectroscopy.     

Stabilization of Cs/Re trapping filters using magnesium phosphate ceramics

The present study a promising method for stabilizing spent filters trapping cesium and technetium by using magnesium phosphate ceramics. Simulated spent filters were fabricated by vaporizing nonradioactive cesium and rhenium (a surrogate of Tc) through the voloxidizer. In order to reveal the characteristics of spent filters, phase structures and thermal stability were analyzed by using X-ray diffraction (XRD), X-ray photoelectron spectroscopy, and thermogravimetric analysis techniques. Waste forms were fabricated by crushing spent filters and mixing them with magnesium oxide and potassium phosphate. Characterizations of the waste forms were performed by the analyses of compressive strength, apparent porosity, XRD, and scanning electron microscopy. The waste forms showed the excellent mechanical property compared with that of ordinary Portland cement, with the highest compressive strength of 38.1 MPa in the sample with 30 wt% of Cs-filter. Microstructural analysis suggests that waste materials are encapsulated by the binding matrix composed of magnesium potassium phosphate. The results of characterization suggest that fabricating a sound and durable waste form is possible with magnesium phosphate ceramics.     

Dye-sensitized solar cells based on trench structured TiO2 nanotubes in Ti substrate

We have proposed dye-sensitized solar cells (DSSCs) with trench-type TiO₂ nanotube structure to improve the low device efficiency of conventional TiO₂ nanotube DSSCs using Ti substrate. Compared to the conventional standing-type TiO₂ nanotube structure based DSSCs, the trench-type TiO₂ nanotube structure based DSSCs have shown an improvement of device efficiency of approximately 40% due to the large increase of Jsc. In the trench-type TiO₂ nanotube structure, the contact area between the TiO₂ nanotube sidewall and the Ti substrate is significantly increased. This increase of contact area provides more charge transport paths than exist in the conventional standing-type TiO₂ nanotube structure and reduces the electrical resistance between the Ti substrate and the TiO₂ nanotubes. Therefore, the remarkable increase of Jsc is the result of the charge collection efficiency, which is improved due to the increase of contact area between the TiO₂ nanotube sidewall and the Ti substrate in the trench-type TiO₂ nanotube structure. The fabrication of the trench-type TiO₂ nanotube structure is an effective manufacturing process for improving the device efficiency of TiO₂ nanotube based DSSCs using Ti substrate. DSSCs having an 11.9 μm thick trench-type TiO₂ nanotube structure have shown an efficiency of 5.74%.     

Effects of substrate temperature on properties of ITO-ZnO composition spread films fabricated by combinatorial RF magnetron sputtering

We have fabricated ITO-ZnO composition spread films to investigate the effects of substrate temperature on their electrical and optical properties by using combinatorial RF magnetron sputtering. It turned out by X-ray measurement that the film with zinc contents above 16.0 at% [Zn/(In+Zn+Sn)] showed amorphous phase regardless of substrate temperature. The amorphous ITO-ZnO film had lower resistivity than polycrystalline films. When the films were deposited at 250 °C, the minimum resistivity of 3.0×10⁻⁴ Ω cm was obtained with the zinc contents of 16.0 at%. The indium content could be reduced as high as ~30 at% compared to that of ITO for the films having similar resistivity (~10⁻⁴ Ω cm). However, a drastic increase of resistivity was observed for the ITO-ZnO films deposited at 350 °C, having zinc contents below 15.2 at%.     

Optimization of Culture Conditions for 1,3-Propanediol Production from Glycerol Using a Mutant Strain of <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis>

In the present work, mutant strains of Klebsiella pneumoniae with deletions of the als gene encoding acetolactate synthase involved in synthesis of 2,3-butanediol, the ldhA gene encoding lactate dehydrogenase required for lactate synthesis, or both genes, were prepared. Production of 1,3-propanediol (1,3-PD) from glycerol was enhanced in the ldhA mutant strain (ΔldhA), but lower in Δals or Δals ΔldhA mutant strains compared to the parent strain, concomitant with a reduction in the glycerol consumption rate, indicating that deletion of ldhA alone was useful to improve 1,3-PD production. Fed-batch fermentation analysis revealed that, in the ΔldhA mutant strain, 1,3-PD production was higher at low pH than at neutral pH; the reverse was true for the parent strain. Further optimization of culture conditions, by variation of aeration and glycerol feed rates, dramatically improved the production of 1,3-PD by the mutant strain. The maximum level attained was 102.7 g l⁻¹ of 1,3-PD from glycerol.     

Self-assembled monolayers made of 6-(5-((6-((5-hexylthiophen-2-yl)ethynyl)-9,10-bis(phenylethynyl)anthracen-2-yl)ethynyl)thiophen-2-yl)hexyl 3-(triethoxysilyl)propylcarbamate for ultrathin film transistors

A new functionalized triethoxysilane bearing an X-shaped, anthracene-based semiconducting molecule on one arm was designed and synthesized as a precursor for the preparation of a self-assembled monolayer (SAM) on a SiO(2) substrate. 3-Isocyanatopropyl triethoxysilane was reacted with a monohydroxyl-terminated X-shaped, anthracene-based semiconducting molecule in the presence of tin catalyst. The 6-(5-((6-((5-hexylthiophen-2-yl)ethynyl)-9,10-bis(phenylethynyl)anthracen-2-yl)ethynyl)thiophen-2-yl)hexyl 3-(triethoxysilyl)propylcarbamate (BATHT-TEOS) was found to be stable and sufficiently reactive to form organic monolayers on hydroxylated SiO(2) surfaces. The structures and properties of these SAMs were investigated using X-ray photoelectron spectroscopy, UV-vis absorption spectroscopy, photoluminescence (PL) spectroscopy, laser scanning confocal microscopy-PL spectrometry, and spectroscopic ellipsometry. In this work, BATHT-SAM was employed as an interfacial layer on SiO(2) to fabricate ultrathin film transistors (UTFTs, active layer thickness ～ 16.09 nm). The device UTFT-I, made of 0.06 wt % 5,5'-(9,10-bis(phenylethynyl)anthracene-2,6-diyl)bis(ethyne-2,1-diyl)bis(2-hexylthiophene) (BATHT) solution on an n-octyltrichlorosilane-SAM/SiO(2) layer, showed no gate effect for the carrier transport behavior; however, the device UTFT-II, fabricated on BATHT-SAM/SiO(2), exhibited field effect mobilities of 0.04 cm(2) V(-1) s(-1) (I(on/off) ～ 6.3 × 10(3) to 1.0 × 10(4)). This can be attributed to the effect of BATHT-SAM inducing uniform coverage and ordering of BATHT molecules as an upper layer.     

Hybridization of DNA to bead-immobilized probes confined within a microfluidic channel

We report the factors influencing the capture of DNA by DNA-modified microbeads confined within a microfluidic channel. Quantitative correlation of target capture efficiency to probe surface concentration, solution flow rate, and target concentration are discussed. The results indicate that the microfluidic system exhibits a limit of detection of approximately 10(-10) M (approximately 10(-16) mol) DNA and a selectivity factor of approximately 8 x 10(3). Typical hybridization times are on the order of minutes.