Conventional radical polymerization and iodine‐transfer polymerization of 4′‐nonafluorobutyl styrene: Surface and thermal characterizations of the resulting poly(fluorostyrene)s

4′‐Nonafluorobutylstyrene (3) was synthesized and polymerized by conventional and controlled radical polymerization (iodine transfer polymerization (ITP)). Such an aromatic fluoromonomer was prepared from Ullmann coupling between 1‐iodoperfluorobutane and 4‐bromoacetophenone followed by a reduction and a dehydration in 50% overall yield. Two radical polymerizations of (3) were initiated by AIBN either under conventional or controlled conditions, with 1‐iodoperfluorohexane in 84% monomer conversion and in 50% yield. ITP of (3) featured a fast monomer conversion and a linear evolution of the ln([M]₀/[M]) versus time. The kinetics of radical homopolymerization of (3) enabled one to assess its square of the propagation rate to the termination rate (k_p²/k_t) in ITP conditions (36.2·10^?2 l·mol^?2·sec^?2 at 80 °C) from the Tobolsky's kinetic law. Polydispersity index (?) of the fluoropolymer achieved by conventional polymerization was 1.30 while it worthed 1.15 when synthesized by ITP. Thermal stabilities of these oligomers were satisfactory (10% weight loss under air occurred from 305 °C) whereas the melting point was 47 °C. Contact angles and surface energies assessed from spin‐coated poly(3) films obtained by conventional (hysteresis = 18°, surface energy 18 mN.m^?1) and ITP (hysteresis = 47°, surface energy 15 mN.m^?1) evidenced ? values' influence onto surface properties of the synthesized polymers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3202–3212     

Atmospheric degradation mechanisms of a simulant organophosphorus pesticide isopropyl methyl methylphosphonate: A theoretical consideration

Calculations using density functional theory were performed to explore the mechanisms for atmospheric degradation of isopropyl methyl methylphosphonate (IMMP). The potential energy surface profiles for OH‐initiated reaction of IMMP were constructed, and all possible degradation channels were considered. Rate constants were further calculated using transition state theory. It was established from these calculations that H‐abstractions from alkyl groups have much lower energy barriers than substitutions of alkoxyl groups, and four possible H‐abstraction channels are competitive. Investigations into the secondary reactions under the presence of O₂/NO were also performed. It is shown that O₂ addition, reaction of peroxide radicals with NO to form RO radicals, and removal of ·RO are the major degradation pathways for alkyl radicals. Four selected products, CH₃OP(O)(CH₃)OC(O)CH₃, CH₃OP(O)(O)CH₃, (CH₃)₂CHOP(O)(CH₃)OH, and (CH₃)₂CHOP(O)(CH₃)OCH?O, are predicted to be the major products in this study. © 2013 Wiley Periodicals, Inc.     

Nonstationarity and related measures for time‐dependent hartree–fock and multiconfigurational models

Based on an earlier article (Eberly and Singh, Phys. Rev. D 1973 , 7, 359) and related works on short‐time evolution, this article proposes a many‐electron formulation for the nonstationarity degree which can be assigned to quantum system at each time point. The key measure introduced, , is a nonstationarity index that can be thought of as an inverse nominal lifetime at each instance of time. The index is directly computed from the time derivative of one‐electron density matrix and is a size‐consistent quantity. In this article, the approach is developed for the time‐dependent Hartree–Fock (TDHF), single‐excitation (TDCIS), and time‐dependent full configuration interaction (TDFCI) models. As a rule, nonstationarity effects are more pronounced in correlated electron systems, and a joint analysis of and the multiconfigurational character of wave functions apparently provide a deeper insight into dynamical molecular processes. The performed calculations on small molecules in laser fields show a preference for the TDCIS model when comparing TDCIS and TDHF with the “exact” TDFCI model. © 2013 Wiley Periodicals, Inc.     

Spectroscopic characterization and preparation of low molecular,water‐soluble chitosan with free‐amine group by novel method

Low molecular, water‐soluble chitosan (LMWSC) with a free amine group was prepared by the novel salts‐removal method described in this study. A weight‐average molecular weight and degree of deacetylation (DDA) of LMWSC were determined by viscometry and Kina titration, resulting in 18,579 Da and 93% DDA, respectively. In the Fourier transform infrared spectroscopic, ¹H NMR, and ¹³C NMR spectra the absorption band by the carboxyl group derived from lactic acid and the impurities formed in the enzymatic process disappeared or were significantly lower than that of the control chitosan. Also, from the ¹H NMR and ¹³C NMR spectra the empirical value for the area ratio of the proton and carbon corresponds nearly to its theoretical values. The matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrum identified the difference in the two adjacent peaks as 161. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3796–3803, 2002     

Fast parallel detection of feline panleukopenia virus DNA by multi‐channel microchip electrophoresis with programmed step electric field strength

A multi‐channel microchip electrophoresis using a programmed step electric field strength (PSEFS) method was investigated for fast parallel detection of feline panleukopenia virus (FPV) DNA. An expanded laser beam, a 10× objective lens, and a charge‐coupled device camera were used to simultaneously detect the separations in three parallel channels using laser‐induced fluorescence detection. The parallel separations of a 100‐bp DNA ladder were demonstrated on the system using a sieving gel matrix of 0.5% poly(ethylene oxide) (M_r = 8 000 000) in the individual channels. In addition, the PSEFS method was also applied for faster DNA separation without loss of resolving power. A DNA size marker, FPV DNA sample, and a negative control were simultaneously analyzed with single‐run and one‐step detection. The FPV DNA was clearly distinguished within 30 s, which was more than 100 times faster than with conventional slab gel electrophoresis. The proposed multi‐channel microchip electrophoresis with PSEFS was demonstrated to be a simple and powerful diagnostic method to analyze multiple disease‐related DNA fragments in parallel with high speed, throughput, and accuracy.     

甲醇乳化柴油分散特性的研究

利用显微摄像技术及算术统计的方法表征了甲醇乳化柴油分散相-甲醇的平均粒径。研究了甲醇乳化柴油分散相（甲醇）的粒径分布随高速分散器转子转速、乳化时间、乳化剂用量和甲醇的质量分数等参数的变化。结果表明,甲醇乳化柴油分散相的平均粒径随转速、乳化剂用量的增加而减小,但随甲醇含量的增加而增大;当乳化时间为2min和转子转速为5×2800r/min,乳化剂的质量分数为5%和甲醇的质量分数为10%时,甲醇乳化柴油中分散相存在最佳的分散度,其值为16μm。
     

Patterned Deposition of Sol-Gel Thin Films Using an Airbrush

ABSTRACT

In this article, we present a method to pattern glass substrates with sol-gel derived thin films. This method is based on the aerosol deposition of sol-gel precursor solutions using an inexpensive, commercially available airbrush. The technique was demonstrated using Cy5-doped sol-gel thin films for the creation of wavelength conversion devices. The films deposited were mechanically and chemically rigid, and patterns could be achieved with a resolution limit of approximately 250 μm. Constructing channel waveguides was also attempted using both zirconium- and titanium-based sol-gel thin films. Deposited thin films of these materials showed graininess that limited the ability to couple light into the films and increased the observed scatter. However, light was successfully coupled into the titanium-based sol-gel film using small lens-like structures created on the glass surface.     

Quartz Crystal Microbalance Biosensor for Saxitoxin Based on Immobilized Sodium Channel Receptors

This work explored the possibility of coupling the toxin receptor-binding principle with the piezoelectric transduction principle. The sensing component of the saxitoxin biosensor involves a piezoelectric quartz crystal that was coated with sodium channel receptors. The sodium channel receptors were isolated from the electroplax organ of Electrophorus electricus. Binding of the sodium channel extracts to the quartz crystal was facilitated by pre-coating the gold electrode with a hydrophobic self-assembled monolayer of dodecanethiol. The instrumentation system consisted of a flow cell that held the quartz crystal, an oscillator circuit, an injection port, and a frequency counter that was connected to a personal computer. The various immobilization and measurement parameters were optimized. Binding of saxitoxin standards with the immobilized sodium channels was monitored through the decrease in the crystal oscillation frequency readings (ΔF) upon the introduction of saxitoxin into the flow cell. A calibration curve for saxitoxin was constructed by plotting the ΔF values vs. saxitoxin concentrations in the range from 0.1 to 2.0 μg/mL. A correlation coefficient of 0.9653 was obtained. The saxitoxin biosensor developed has the potential to be applied to the rapid screening of total paralytic shellfish poisoning toxins.