Novel Radio on Fiber Access Eliminating External Electric Power Supply at Base Station

A novel Radio On Fiber(ROF) access is proposed and demonstrated which enables the pico-cell Base Station (BS) for high-speed wireless communications to eliminate external electric power supply facilities. We demonstrated 2.4-GHz band radio signal transmission through the BS without external electric power supply. The electrical power used for BS circuit is feeded by optical power over optical fiber from central station.     

Speckle contrast evaluation of multi-emitter broad area 638-nm red laser diodes

Speckle contrast of single, dual, and triple emitter broad area laser diodes (BA-LDs) with a wavelength of 638 nm was experimentally investigated. Speckle noise was relatively small near the threshold current probably due to the longitudinal mode competition. Higher output power led to smaller speckle noise owing to the spectrum widening. A wide stripe presented an advantage in terms of speckle reduction in the single emitter LDs. It is also found that wider emitter width leads to the smaller the speckle noise. A larger number of emitters decreased speckle noise due to the beam superposition effect, even for multi-emitter LDs in which the emitters are built into one chipa.

     

Three-dimensional microscopic interlaminar analysis of cross-ply laminates based on a homogenization theory

In this study, a method for three-dimensional microscopic interlaminar analysis of cross-ply laminates is developed based on a homogenization theory to analyze microscopic interactions between unidirectional long fiber-reinforced laminae. For this, a unit cell of a cross-ply laminate, which includes interlaminar areas, is defined under the assumption that each lamina in the laminate has a transversely square fiber array. Then, showing that the laminate has a point-symmetric internal structure, the symmetry is utilized to introduce half of the unit cell as the domain of analysis. Moreover, the domain of analysis is divided into substructures using a substructure method combined with the homogenization theory, significantly reducing the computational costs. The present method is then applied to the analysis of interlaminar stress distributions in a carbon fiber/epoxy cross-ply laminate subjected to in-plane uniaxial tension. It is shown that microscopic shear stress noticeably occurs at the interface between the 0°- and 90°-plies. It is also shown that the microscopic interaction between the two plies is observed only in the vicinity of the interface.     

Synthesis and Self‐Assembly of NCN‐Pincer Pd‐Complex‐Bound Norvalines

The NCN‐pincer Pd‐complex‐bound norvalines Boc‐D /L ‐[PdCl(dpb)]Nva‐OMe ( 1 ) were synthesized in multigram quantities. The molecular structure and absolute configuration of 1 were unequivocally determined by single‐crystal X‐ray structure analysis. The robustness of 1 under acidic/basic conditions provides a wide range of N‐/C‐terminus convertibility based on the related synthetic transformations. Installation of a variety of functional groups into the N‐/C‐terminus of 1 was readily carried out through N‐Boc‐ or C‐methyl ester deprotection and subsequent condensations with carboxylic acids, R¹COOH, or amines, R²NH₂, to give the corresponding N‐/C‐functionalized norvalines R¹‐D /L ‐[PdCl(dpb)]Nva‐R² 2 – 9 . The dipeptide bearing two Pd units 10 was successfully synthesized through the condensation of C‐free 1 with N‐free 1 . The robustness of these Pd‐bound norvalines was adequately demonstrated by the preservation of the optical purity and Pd unit during the synthetic transformations. The lipophilic Pd‐bound norvalines L ‐ 2 , Boc‐L ‐[PdCl(dpb)]Nva‐NH‐n‐C₁₁H₂₃, and L ‐ 4 , n‐C₄H₉CO‐L ‐[PdCl(dpb)]Nva‐NH‐n‐C₁₁H₂₃, self‐assembled in aromatic solvents to afford supramolecular gels. The assembled structures in a thermodynamically stable single crystal of L ‐ 2 and kinetically stable supramolecular aggregates of L ‐ 2 were precisely elucidated by cryo‐TEM, WAX, SAXS, UV/Vis, IR analyses, and single‐crystal X‐ray crystallography. An antiparallel β‐sheet‐type aggregate consisting of an infinite one‐dimensional hydrogen‐bonding network of amide groups and π‐stacking of PdCl(dpb) moieties was observed in the supramolecular gel fiber of L ‐ 2 , even though discrete dimers are assembled through hydrogen bonding in the thermodynamically stable single crystal of L ‐ 2 . The disparate DSC profiles of the single crystal and xerogel of L ‐ 2 indicate different thermodynamics of the molecular assembly process.     

Specific Detection and Imaging of Enzyme Activity by Signal‐Amplifiable Self‐Assembling 19F MRI Probes

Specific turn‐on detection of enzyme activities is of fundamental importance in drug discovery research, as well as medical diagnostics. Although magnetic resonance imaging (MRI) is one of the most powerful techniques for noninvasive visualization of enzyme activity, both in vivo and ex vivo, promising strategies for imaging specific enzymes with high contrast have been very limited to date. We report herein a novel signal‐amplifiable self‐assembling ¹⁹F NMR/MRI probe for turn‐on detection and imaging of specific enzymatic activity. In NMR spectroscopy, these designed probes are “silent” when aggregated, but exhibit a disassembly driven turn‐on signal change upon cleavage of the substrate part by the catalytic enzyme. Using these ¹⁹F probes, nanomolar levels of two different target enzymes, nitroreductase (NTR) and matrix metalloproteinase (MMP), could be detected and visualized by ¹⁹F NMR spectroscopy and MRI. Furthermore, we have succeeded in imaging the activity of endogenously secreted MMP in cultured media of tumor cells by ¹⁹F MRI, depending on the cell lines and the cellular conditions. These results clearly demonstrate that our turn‐on ¹⁹F probes may serve as a screening platform for the activity of MMPs.     

Preparation of Ordered Mesoporous Alumina‐Doped Titania Films with High Thermal Stability and Their Application to High‐Speed Passive‐Matrix Electrochromic Displays

Ordered mesoporous alumina‐doped titania thin films with anatase crystalline structure were prepared by using triblock copolymer Pluronic P123 as structure‐directing agent. Uniform Al doping was realized by using aluminum isopropoxide as a dopant source which can be hydrolyzed together with titanium tetraisopropoxide. Aluminum doping into the titania framework can prevent rapid crystallization to the anatase phase, thereby drastically increasing thermal stability. With increasing Al content, the crystallization temperatures tend to increase gradually. Even when the Al content doped into the framework was increased to 15 mol %, a well‐ordered mesoporous structure was obtained, and the mesostructural ordering was still maintained after calcination at 550 °C. During the calcination process, large uniaxial shrinkage occurred along the direction perpendicular to the substrate with retention of the horizontal mesoscale periodicity, whereby vertically oriented nanopillars were formed in the film. The resulting vertical porosity was successfully exploited to fabricate a high‐speed and high‐quality passive‐matrix electrochromic display by using a leuco dye. The vertical nanospace in the films can effectively prevent drifting of the leuco dye.     

Living Radical Polymerization of Styrene with Diphenyl Diselenide as a Photoiniferter. Synthesis of Polystyrene with Carbon-Carbon Double Bonds at Both Chain Ends

Abstract

Photopolymerization of styrene in the presence of diphenyl diselenide proceeded smoothly. The polymer yields and the number average molecular weight (Mn) of the polymers increased with reaction time. Further, a linear relationship was found for a plot of Mn for polystyrene versus polymer yield. These results indicate that this polymerization proceeds through a living radical mechanism. Photopolymerization of styrene with bis(p-tertbutylphenyl) diselenide afforded a telechelic polystyrene with terminal arylseleno groups. The resulting polymer underwent the reductive elimination of terminal seleno groups by the reaction with tri-n-butyltin hydride. Moreover, this telechelic polymer was treated with hydrogen peroxide to afford polystyrene with carbon-carbon double bonds at both chain ends.     

Sulfur-Containing Vinyl Monomers. XIV. Radical Polymerizations and Copolymerizations of Vinyl Mercaptobenzazoles

Vinyl mercaptobenzazoles [thiazole (VMBT), oxazole (VMBO), and imidazole (VMBI)] were prepared through dehydrochlorination of the respective β-chloroethyl mercaptobenzazoles. These monomers were found to undergo vinyl polymerization in the presence of light or radical initiator, α,α'-azobisisobutyonitrile, to give relatively high molecular weight homopolymers. From the results of radical copolymerizations of these monomers with various monomers, the copolymerization parameters were determined as follows: VMBT(M₂): r₁ styrene(M₁): r₁ = 2.12 ± 0.09, r₂ = 0.336 ± 0.028, Q₂ = 0.75, e_z = ?1.38; VMBO(M₂)-styrene(M₁): r₁ = 2.61 ± 0.13, r₂ = 0.274 ± 0.03, Q₂ = 0.61, e₂ = ?1.38; VBMI(M₂)-styrene(M₁) r₁ =4.0, r₂ = 0.2, Q₂ = 0.37, e₂ = ?1.17. The polymerization reactivities of these monomers obtained from these parameters were compared with those of other vinyl sulfide monomers and discussed.     

Effect of Fermentation Conditions on the Flocculation of Recombinant Saccharomyces cerevisiae Capable of Co-fermenting Glucose and Xylose

Flocculation is a desirable property in industrial yeasts and is particularly important in the fuel ethanol industry because it provides a simple and cost-free way to separate yeast cells from fermentation products. In the present study, the effect of pH and lignocellulose-derived sugars on yeast flocculation was investigated using a flocculent Saccharomyces cerevisiae, MA-R4, which has been recombinantly engineered to simultaneously co-ferment glucose and xylose to ethanol with high productivity. The flocculation level of MA-R4 dramatically decreased at pH values below 3.0 during co-fermentation of glucose and xylose. Sedimentation and microscopic observation revealed that flocculation was induced in MA-R4 when it fermented glucose, a glucose/xylose mixture, or mannose, whereas attempts to ferment xylose, galactose, and arabinose led to the loss of flocculation. MA-R4 fermented xylose and galactose more slowly than glucose and mannose. Therefore, the various flocculation behaviors shown by MA-R4 should be useful in the control of ethanol fermentation processes.