Dual Electrode Ensembles with Core and Shell Nanoelectrodes for Dopamine Sensing Applications

This paper presents the fabrication of dual electrode ensembles for electrochemical sensing of dopamine. A new dual electrode ensemble consists of vertically aligned core nanowire electrodes and a shell electrode with a hemi‐cylindrical nanocavity structure and submicron inter‐electrode spacing between the two working electrodes. By using a 3‐dimensional cavity structure of two working electrodes, collection efficiency in redox cycling of dopamine is enhanced. Initial measurement results show the ability to detect 200 μM concentration of dopamine with 69% collection efficiency on a dual electrode ensemble.     

Synthesis and electro‐optical properties of light‐emitting polymers containing oxadiazole derivatives for light‐emitting diodes applications

Two PPV‐based bipolar polymers containing 1,3,4‐oxadiazole pendant groups were synthesized via the Gilch polymerization reaction for use in light‐emitting diodes (LEDs). The resulting polymers were characterized using ¹H and ¹³C NMR, elemental analysis, DSC, and TGA. These polymers were found to be soluble in common organic solvents and are easily spin‐coated onto glass substrates, producing high optical quality thin films without defects. The electro‐optical properties of ITO/PEDOT/polymer/Al devices based on these polymers were investigated using UV‐visible, PL, and EL spectroscopy. The turn‐on voltages of the OC₁Oxa‐PPV and OC₁₀Oxa‐PPV devices were found to be 8.0 V. The maximum brightness and luminescence efficiency of the OC₁Oxa‐PPV device were found to be 544 cd/m² at 19 V and 0.15 cd/A, respectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1098–1110, 2008     

Design and fabrication of electrospun polyethersulfone nanofibrous scaffold for high‐flux nanofiltration membranes

A novel class of high‐flux and low‐fouling thin‐film nanofibrous composite (TFNC) membranes, containing a thin hydrophilic top‐layer coating, a nanofibrous mid‐layer scaffold and a non‐woven microfibrous support, has been demonstrated for nanofiltration (NF) applications. In this study, the issues related to the design and fabrication of a polyethersulfone (PES) electrospun nanofibrous scaffold for TFNC NF membranes were investigated. These issues included the influence of solvent mixture ratio, solute concentration, additives, relative humidity (RH), and solution flow rate on the morphology of an electrospun PES nanofibrous scaffold, the distribution of fiber diameter, the adhesion between the PES scaffold and a typical poly(ethylene terephthalate) (PET) non‐woven support, as well as the tensile properties of the nanofibrous PES/non‐woven PET composite substrates. Uniform and thin nanofibrous PES scaffolds with strong adhesion to the nanofiber‐PET non‐woven are several of the key parameters to optimize the NF performance of TFNC membranes. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2288–2300, 2009     

Effect of particle number density in in-line digital holographic particle velocimetry

A digital in-line holographic particle tracking velocimetry (HPTV) system was developed to measure 3D (three-dimensional) velocity fields of turbulent flows. The digital HPTV (DHPTV) procedure consists of four steps: recording, numerical reconstruction, particle extraction and velocity extraction. In the recording step, a digital CCD camera was used as a recording device. Holograms contained many unwanted images or noise. To get clean holograms, digital image processing techniques were adopted. In the velocity extraction routine, we improved the HPTV algorithm to extract 3D displacement information of tracer particles. In general, the results obtained using HPTV were not fully acceptable due to technical limitations such as low spatial resolution, small volume size, and low numerical aperture (NA). The problems of spatial resolution and NA are closely related with a recording device. As one experimental parameter that can be optimized, we focused on the particle number density. Variation of the reconstruction efficiency and recovery ratio were compared quantitatively with varying particle number density to check performance of the developed in-line DHPTV system. The reconstruction efficiency represented the particle number distribution acquired through the numerical reconstruction procedure. In addition the recovery ratio showed the performance of 3D PTV algorithm employed for DHPTV measurements. The particle number density in the range of C _o = 13–17 particles/mm³ was found to be optimum for the DHPTV system tested in this study.     

Structural stabilization of phase separating PC/polyester blends through interfacial modification by transesterification reaction

Competition between phase separation and transesterification in immiscible polymer blends of polycarbonate (PC) and a copolyester (PET) is studied as a function of time and temperature by differential scanning calorimetry (DSC) and small-angle neutron scattering (SANS). We found that (1) Global structure coarsens at T ≤ 200°C due to the dominance of phase separation over transesterification and melts at T ≤ 220°C due to the dominance of transesterification at the domain interface. However, transesterification is slow but still significant even at T ≤ 200°C. (2) An intricate balance of transesterification and phase separation rates controls global and interfacial structures. (3) Interfacial structures become measurable under certain conditions, and the interfacial thickness between PC or PET and the copolymers generated by transesterification increases with time. (4) DSC results are consistent with results obtained by SANS, but the latter is more sensitive than the former and differentiates the structural change at different length scales caused by phase separation and transesterification. © 1994 John Wiley & Sons, Inc.     

Perpendicular anisotropy of Co3Pt deposited on the NiFeMo/Ru buffer

The multilayer of Ta/NiFeMo/Ru/Co₃Pt was sputter deposited on the Si (1 0 0) wafer. Using the NiFeMo buffer layer greatly enhanced the texture of Co₃Pt layer. The enhanced texture increased the perpendicular magnetic anisotropy of Co₃Pt. According to the VSM and XRD results, only the 5 nm of NiFeMo was good enough to produce the texture and perpendicular anisotropy in Co₃Pt layer. The perpendicular anisotropy was attributed to the existence of short-range-ordered HCP structure of Co₃Pt.     

Model-based clustering for integrated circuit yield enhancement

This paper studies the defect data analysis method for semiconductor yield enhancement. Given the defect locations on a wafer, the local defects generated from the assignable causes are classified from the global defects generated from the random causes by model-based clustering, and the clustering methods can identify the characteristics of local defect clusters. The information obtained from this method can facilitate process control, particularly, root-cause analysis. The global defects are modeled by the spatial non-homogeneous Poisson process, and the local defects are modeled by the bivariate normal distribution or by the principal curve.