Broadband Light Source for Wavelength-Division Multiple Access Passive Optical Network

We demonstrated a unified two-band broadband light source based on erbium-doped fiber. The proposed scheme generates high output power at both bands and saves doped-fiber and pump lasers.     

Structural and electrical properties of core–shell structured GaP nanowires with outer Ga2O3 oxide layers

This paper presents a review of our current experimental research on GaP nanowires grown by a vapor deposition method. Their structural, electrical, opto-electric transport, and gas-adsorption properties are reviewed. Our structural studies showed that a GaP nanowire consisted of a core–shell structure with a single-crystalline GaP core and an outer Ga₂O₃ layer. The individual GaP nanowires exhibited n-type field effects. Their electron mobilities were in the range of about 6 to 22 cm²/V s at room temperature. When the nanowires were illuminated with an ultraviolet light source, an abrupt increase of conductance occurred resulting from carrier generation in the nanowire and de-adsorption of adsorbed OH^- or O₂ ^- ions on the Ga₂O₃ surface shell. Using an intrinsic Ga₂O₃ shell layer as a gate dielectric, top-gated GaP nanowire field-effect transistors were fabricated and characterized. Like other metal oxide nanowires, the carrier concentration and mobility of GaP nanowires were significantly affected by the surface molecular adsorption of OH or O₂. The GaP nanowire devices were fabricated as sensors for NO₂, NH₃, and H₂ gases by using a simple metal decoration technique. PACS 73.63.-b; 72.80.Ey; 85.35.-p     

沉积物中壬基苯酚类雌性激素化合物的加速溶剂提取方法研究

为了同时提取和检测沉积物中的雌性激素化合物对壬基苯酚(NP)、对壬基苯酚一乙氧醚(NP1EO)和对壬基苯酚二乙氧醚(NP2EO),对加速溶剂提取体系的各种条件和对壬基苯酚类化合物的硅烷基化反应条件等进行了优化。在丙酮和丙酮-二氯甲烷混合液(丙酮含量≥60%)介质中,这些化合物的硅烷基化反应很快达到反应终点。加速溶剂提取体系的最佳提取条件是120℃、8.4MPa、两次循环提取;最佳提取溶剂是二氯甲烷。与索氏提取和酸化悬浮液液提取比较,明显提高了提取率、重现性和准确性。平均添标回收率在89.3%~95.7%之间,相对标准偏差为2.3%~13.4%。本方法对壬基苯酚、对壬基苯酚一乙氧醚和对壬基苯酚二乙氧醚化合物的检出限分别为10、30、35ng/gdw(干重)。     

Synthesis and characterization of novel perfluorinated polyimides with 3D‐controlled structures for photonic applications

We have designed and synthesized novel perfluorinated polyimides with 3D controlled structure. At first, we successfully developed the new synthetic routes to diamines with pendant bulky perfluorinated aromatic units in a multi‐step synthetic procedure. Novel perfluorinated polyimides were prepared in a two‐step reaction in N‐methyl‐2‐pyrrolidinone (NMP) solution: The first step was for the synthesis of polyamic acids (PAAs) and the second reaction was for the imidization of PAA. The polymer yield was over 89% and the inherent viscosity of PAAs was in the range of 0.24–0.36 dL/g. The thin films were prepared by spin‐coating the PAA solution in NMP onto various substrates such as a Si wafer or a KBr pellet, dried at 80 °C and further cured at 230 °C. The resultant polyimides are thermally stable over 400 °C. The refractive index and birefringence of the resultant polyimides are 1.5858–1.6452 and 0.01–0.005, respectively. The refractive index of polyimide decreases with increasing the fluorine content. The copolymerization and the ether linkages into the backbone reduce the birefringence of polyimides. Surprisingly, the pendant ether linkage is not a crucial factor in reducing the polyimide birefringence. Their birefringence is comparatively very low, compared with that of previous polyimides. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1326–1342, 2006     

A pair of orthogonal frames

We start with a characterization of a pair of frames to be orthogonal in a shift-invariant space and then give a simple construction of a pair of orthogonal shift-invariant frames. This is applied to obtain a construction of a pair of Gabor orthogonal frames as an example. This is also developed further to obtain constructions of a pair of orthogonal wavelet frames.     

Suppressed beta-hydride elimination in palladium-catalyzed cascade cyclization-coupling reactions: an efficient synthesis of 3-arylmethylpyrrolidines

[formula: see text] A novel type of palladium-catalyzed cascade cyclization-coupling reaction that proceeds with suppressed beta-hydride elimination has been found. One of the N-sulfonyl oxygens is suggested to coordinatively stabilize an alkylpalladium intermediate, thus preventing the intermediate from the usual beta-elimination. This is the first sequential palladium-catalyzed coupling reaction where the Suzuki and Heck reactions can compete. The reaction provides an efficient synthetic route to 4-methylene-3-arylmethylpyrrolidines, which are not readily available by other routes.     

Sequence- and site-specific photodissociation at 266 nm of protonated synthetic polypeptides containing a tryptophanyl residue

Photodissociation at 266 nm of protonated synthetic polypeptides containing a tryptophanyl residue was investigated using a homebuilt tandem time-of-flight mass spectrometer equipped with a matrix-assisted laser desorption/ionization source. Efficient photodissociation of the protonated peptides was demonstrated. Most of the intense peaks in the laser-induced tandem mass spectra were sequence ions. Furthermore, sequence ions due to cleavages at all the peptide bonds were observed; this is a feature of the technique that is particularly useful for peptide sequencing. Fragmentations at both ends of the tryptophanyl residue were especially prevalent, which can be useful for location of the tryptophanyl chromophore in a peptide.     

Osteoprotegerin is present on the membrane of osteoclasts isolated from mouse long bones

Osteoprotegerin (OPG), a member of the tumor necrosis factor receptor superfamily, is known to inhibit osteoclastogenesis by acting as a soluble decoy receptor for the receptor activator of NF-kappaB ligand (RANKL). We report the presence of OPG on the membrane of osteoclasts and the possibility of the direct action of OPG on them. Highly pure osteoclast precursors were isolated from mouse long bones and induced to differentiate into mature osteoclasts by M-CSF and soluble RANKL (sRANKL). The presence of OPG on the membrane of these cells was confirmed by western blotting and immunostaining. Furthermore, sRANKL was found to be bound to the OPG on the osteoclast precursors. These results suggest that OPG might have a new role during the differentiation of osteoclasts beyond its role as a soluble decoy receptor. The mechanism of the existence of OPG on osteoclast precursors remains to be found.