Fused-Polished Fiber Couplers

We report on fused-polished fiber couplers with a new fabrication method. This structure so fabricated is promising while achieving high-performance all-fiber WDM devices. Potential advantages and prospects of our works are presented.     

On some interior-point algorithms for nonconvex quadratic optimization

 Recently, interior-point algorithms have been applied to nonlinear and nonconvex optimization. Most of these algorithms are either primal-dual path-following or affine-scaling in nature, and some of them are conjectured to converge to a local minimum. We give several examples to show that this may be untrue and we suggest some strategies for overcoming this difficulty. Received: June 26, 2000 / Accepted: April 2002 Published online: September 5, 2002 Key words. Nonconvex quadratic optimization – local minimum – interior-point algorithms – trust region – branch-and-cut This research is supported by the National Science Foundation Grant CCR-9731273 and DMS-9703490.     

COULOMB BLOCKADE EFFECT INSELF-ASSEMBLED GOLD QUANTUM DOTS

Nanometer-scale Au quantum dots have been assembled on SiO2 by controlling the reaction of raw matedais to form a citrate Au sol and an aminosilane/dithiol-treated patterned Si wafer. The detailed formation mechanism has been studied. Three gold colloidal particles (-15 nm), aligned in a chain to form a one-dimensional current path, was bridged across an 80-nm gap between source and drain metal electrodes, The device exhibited a Coulomb blockade effect at 33 K.     

Three‐dimensional thermal annealing: An unconventional method to fabricate monodisperse polymer nanoparticles from polymer films

We develop a simple and feasible method to fabricate polymer nanoparticles by annealing polymer films in a uniform environment. Different from the conventional methods, no extra additive or emulsifier is needed in the preparation processes. Poly(methyl methacrylate) (PMMA) films are used as a model system and annealed at elevated temperatures in ethylene glycol, which provides a uniform three‐dimensional annealing environment and acts as stabilizers once the nanoparticles are formed. After the annealing process, PMMA nanoparticles with monodisperse diameters are formed. By examining the remaining films after the annealing process, the formation mechanism, which involves surface undulation and detachment of polymer nanoparticles, is proposed. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 2471–2475     

A matrix-induced ion suppression method to normalize concentration in urinary metabolomics studies using flow injection analysis electrospray ionization mass spectrometry

Normalizing the total urine concentration is important for minimizing bias in urinary metabolomics analysis comparisons. In this study, we report a matrix-induced ion suppression (MIIS)-based method to normalize concentration using flow injection analysis coupled with electrospray ionization mass spectrometry (FIA-ESI-MS). An ion suppression indicator (ISI) was spiked into urine samples, and the intensity of the extracted ion chromatogram (EIC) for ISI in a urine matrix was subtracted by the EIC for a blank solution and used to calculate the extent to which the signal was reduced by the urine matrix. A series dilution of pooled urine samples was used to correlate the urine concentration and level of ion suppression for ISI. A regression equation was used to estimate the relative concentration of unknown urine samples. The MIIS method was validated for linearity, precision and accuracy. We obtained a good correlation using a quadratic regression model for 1- to 32-fold urine dilutions (R² = 0.998). The reproducibility (n = 4) and intermediate precision (n = 3) were below 5% RSD, and the accuracy ranged from 97.15% to 102.10%. The established method was used to estimate the relative concentrations of 16 urine samples, and the results were compared with commonly used normalization methods. Pearson’s correlation test was used to demonstrate that the MIIS method correlated highly with the creatinine and osmolarity methods; the correlation coefficients were 0.93 and 0.99, respectively. We successfully applied this method to a urinary metabolomics study on breast cancer. This study demonstrated the MIIS method is simple, accurate and can contribute to data integrity in urinary metabolomics studies.     

Divergent Reactivity of Rhodium(I) Carbenes Derived from Indole Annulations

Rhodium(I) carbenes were generated from propargylic alcohol derivatives as the result of a dehydrative indole annulation. Depending on the choice of the electron‐withdrawing group on the aniline nitrogen nucleophile, either a cyclopropanation product or dimerization product was obtained chemoselectively. Intramolecular hydroamidation occurred for the same type of propargylic alcohol derivatives when other transition‐metal catalysts were employed.     

Three New Benzophenone Glucosides from the Leaves of Planchonella obovata

Chemical investigation of the EtOH extract of the leaves of Planchonella obovata resulted in the isolation of four benzophenone glucosides, 1 – 4 , of which three, 2 – 4 , are new chemical entities together with five known flavonol glycosides. Their structures were elucidated by spectroscopic analysis. Among the isolated compounds, iriflophenone 2‐O‐(2,6‐di‐O‐galloyl)‐β‐D ‐glucopyranoside ( 4 ) showed some activity (91.4 and 15.0% inhibition at 100 and 10 μg/ml, resp.) against the α‐glucosidase of Bacillus stearothermophilus.     

PREPARATION OF LARGE-PARTICLE-SIZE MONODISPERSE LATEXES IN SPACE: POLYMERIZATION KINETICS AND PROCESS DEVELOPMENT

Monodisperse polystyrene latexes are prepared by seeded emulsion polymerization; however, sizes larger than 2μm are difficult to prepare because of the creaming and settling of the particles, and their sensitivity to mechanical shear. Preparation in space would obviate the creaming and settling, and allow agitation just sufficient for good heat transfer and mixing. Three polymerizations yielding 3-5μm size particles were carried out successfully on the third flight of the “Columbia” launched March 22, 1982; however, four polymerizations yielding sizes up to 10μm on the fourth flight launched June 27, 1982, were incomplete owing to apparatus malfunction. The results of these polymerizations and the prospects of developing a preparative space process are reviewed     

Core deflection in injection molding

Core bending often complicates the injection molding of thin slender parts. Here, a fifth order nonlinear ordinary differential equation is derived for core deflection caused by a Newtonian liquid race tracking through the slit between the core and the rigid cavity wall. Solving this numerically, a universal graph is produced to help engineers predict core deflection. For small core deflections, explicit analytical solutions for these deflections and for the pressure developed in the race tracking fluid are also derived. We find that core deflection is governed by a single dimensionless group called core deflectability. Core deflection measurements agree closely with predictions of this fifth order nonlinear theory.