Multistage homotopy perturbation method for nonlinear reaction networks

In this paper, we present the multistage homotopy perturbation method for finding the solution of the chemical kinetics with nonlinear reactions. We develop a general scheme for finding the analytic solution of chemical reaction networks and apply it to motivating chemical examples such as the enzyme kinetics model and the Brusselator model. We illustrate the numerical result for the models and show the accuracy of the method.     

Synthesis and characterization of thermally crosslinkable hole‐transporting polymers for PLEDs

Two new thermally crosslinkable hole‐transporting polymers, X‐PTPA and X‐PCz, were synthesized via Yamamoto coupling reactions. The number‐averaged molecular weights (M_n) of X‐PTPA and X‐PCz were found to be 45,000 and 48,000, respectively, and therewith, polydispersity indices were of 1.8 and 1.7, respectively. Thermally crosslinked X‐PTPA and X‐PCz exhibit excellent solvent resistance and stable optoelectronic properties. The UV–visible maximum absorption peaks of X‐PTPA and X‐PCz in the thin film state are at 389 and 322 nm, respectively. The HOMO levels of X‐PTPA and X‐PCz are estimated to be ?5.27 and ?5.39 eV, respectively. Multilayered devices (ITO/crosslinked X‐PTPA or X‐PCz/SY‐PPV/LiF/Al) were fabricated with SY (SuperYellow) as the emitting layer. The maximum efficiency of the multilayered device with a crosslinked X‐PTPA layer is approximately three times higher than that of the device without a crosslinked X‐PTPA layer and much higher than that of the crosslinked X‐PCz device. This result can be explained by the observations that crosslinked X‐PTPA produces increased electron accumulation within the emitter, SY, and also efficient exciton formation due to improved charge balance. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5111–5117     

Curing temperature- and concentration-dependent dielectric properties of cross-linked poly-4-vinylphenol (PVP)

In this paper, dielectric properties of various thick PVP films cured at temperatures between 125° C and 200 °C are investigated. The thicknesses of PVP films are adjusted by varying their concentration in PGMEA solvent from 10 wt% to 2.5 wt%. Through FT-IR, C–V, SEM, and AFM analyses, the optimum curing process temperatures (150 °C for 10 wt% and 7.5 wt% samples, and 175 °C for 5 wt% samples) where PET substrates can be thermally endured are proposed in terms of their low hysteresis voltage in the C–V curve (1–2 V in 10 wt% samples, below 1 V in 7.5 wt% samples, and 0.5 V in 5 wt% samples).     

Real‐Time Measurement of the Size Distribution of Diesel Exhaust Particles using a Portable 4‐stage Electrical Low Pressure Impactor

For this study, a 4 stage electrical low pressure impactor was designed to measure the real‐time size distribution of diesel particulate matter (DPM). For the performance evaluation, sodium chloride (NaCl) particles and dioctyl sebacate (DOS) particles were used. After evaluating the collection efficiency of each stage of the impactor, the size distributions of test particles were estimated using electrical current data and their inversion algorithm, and this was found to agree with the results obtained by a scanning mobility particle sizer (SMPS). For measurement of DPM, a common‐rail direct injection (CRDI) diesel engine, for engine speeds of 1,200 rpm and 1,500 rpm at 2.7 kgf·m, was used. Therefore, it was found that the size distribution of the DPM could be easily obtained, with the currents measured by the impactor and the data inversion algorithm, in less than 5 seconds. Furthermore, the effective density of the DPM could be obtained using the calculated results and the SMPS data.     

Upper bounds on the symbol-error probability of MPSK with phase error using pawula F-function IV

This letter presents an alternative derivation of the Case IV of Pawula F-function and an approximation for the corresponding probability density function (pdf) in the presence of the Tikhonov distributed phase error. The pdf of Case IV is used to obtain new upper bounds for the conditional and average symbol-error probabilities of M-ary phase shift keying with phase error over additive white Gaussian noise channels. Numerical results demonstrate the validity of the upper bounds.     

Liquid chromatographic resolution of racemic rasagiline and its analogues on a chiral stationary phase based on (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid

A liquid chromatographic chiral stationary phase based on (+)‐(18‐crown‐6)‐2,3,11,12‐tetracarboxylic acid was applied to the resolution of 15 analytes, including racemic rasagiline, a chiral drug for the treatment of Parkinson's disease, and its analogues. The composition of mobile phase was optimized to be ethanol/acetonitrile/acetic acid/triethylamine (80:20:0.2:0.3, v/v/v/v) by evaluating the chromatographic results for the resolution of five selected analytes under various mobile phase conditions. Under the optimized mobile phase conditions, racemic rasagiline was resolved quite well with a separation factor of 1.48 and resolution of 2.71 and its 14 analogues were also resolved reasonably well with separation factors of 1.06–1.54 and resolutions of 0.54–2.11. Among 15 analytes, racemic rasagiline was resolved best except for just one analyte. The analyte structure–enantioselectivity relationship indicated that racemic rasagiline has the most appropriate structural characteristics for resolution on the chiral stationary phase.     

Organocatalytic Conjugate Addition of Azide Ion to α,β‐Unsaturated Aldehydes

An efficient and simple amine‐catatalyzed azide conjugate addition to α,β‐unsaturated aldehydes has been developed. In the presence of a catalytic amount of tertiary amine with a 1:1 mixture of NaN₃ and 37% HCl in CH₂Cl₂, α,β‐unsaturated aldehydes provided β‐azido aldehydes, which could be transformed into 1,3‐amino alcohols.