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Intrinsically soluble terpolymers with alternating conjugated chromophoric units with inert hexane-1,6-dioxy units were synthesized using the Wittig reaction. The terpolymers were characterized with FTIR, 1H NMR, UV–vis and fluorescence techniques. The thermal properties were investigated with DSC and TGA under nitrogen atmosphere. The photoluminescence of the terpolymer films was found to have emissive region and emission maxima, λem, similar to that of poly(2,5-dimethoxy-1,4-phenylenevinylene) films prepared via the Wessling method. A forward bias current was obtained and the devices showed typical diode behaviour. The photodegradation of the terpolymer films was studied by applying low-intensity irradiation at a fixed wavelength to the film.

Water-soluble copolymers of N-acryloyl-N′-alkylpiperazine (alkyl: methyl, ethyl) with methyl methacrylate were synthesized and the lower critical solution temperatures (LCSTs) of the copolymers which depend on the compositions and pH of the aqueous solutions are described. The effects of cationic surfactants and simple inorganic salts on the LCSTs are also reported. The influences of pH and temperature on the swelling of the ionizable and thermosensitive hydrogels are studied.

Intrinsically soluble copolymer with well-defined alternating substituted 2.5 p-phenylenevinylene (2.5 PV) and hexanedioxy blocks was synthesized by using the Wittig reaction. The copolymer was characterized with FTIR, 1H NMR, UV–vis and fluorescence techniques. Thermal properties were investigated with DSC and TGA under nitrogen atmosphere. Time-resolved studies done on the polymer solution and film indicate that the polymer has a recombination time in the region of 20μs, which is four order of magnitude greater than that reported for the PPV. A single-layer light-emitting diode device having a simple ITO/polymer/Al configuration was fabricated. The forward bias current was obtained and the device shows typical diode behaviour. Photodegradation of the copolymer was also studied by applying high-intensity UV illumination as well as low-intensity irradiation at a fix wavelength to the polymer film.

In an attempt to clone and express proteins from the Epstein‐Barr virus (EBV) cDNA library to be used as antigens in an enzyme‐linked immunosorbent assay (ELISA) format to test against the antibodies found in the sera of nasopharyngeal carcinoma (NPC) patients, we have isolated and characterized three clones. All three clones expressed the same polypeptides of different lengths, which belong to the carboxyl terminal end of the large subunit of ribonucleotide reductase (RR) of the EBV genome. All three clones were found to be immunogenic and could be used in an IgA and IgG ELISA against the NPC sera with various degrees of sensitivity and specificity. Because the clones varied in length, this difference provides a simple system to determine where most of the antibody epitopes lies on the protein. We designed an immunoabsorption assay and a mathematical model to help map the segment of the polypeptide most immunogenic to 43 NPC patients. Results were unexpected: 77% of the patients were most immunogenic to region z, which was the smallest fragment among the three fragments studied. Fragment zwas only 33 amino acids in length. Only 14% and 19% of patients showed the most immunogenic region in segment xand y,respectively. This variation could be due to major histocompatibility complex antigens. The patients could be divided into three groups based on the immunoabsorption assays, in which each group responded to a different immunodominant segment in the RR antigen. The largest group responded to an immunodominant segment, which was only 33 amino acids long. This domain was coded for by the gene fragment from nucleotide 78,129 to nucleotide 78,227 of the EBV genome. This segment of the protein would be suitable for further epitope mapping studies. J. Med. Virol. 58:385–396, 1999. © 1999 Wiley‐Liss, Inc.

The surface structures of polypyrrole/silicon crosslinked poly( styrene/butyl acrylate/hydroxyethyl acrylate) (PSBH) conductive composite films were investigated by X-ray photoelectron spectroscopy and scanning electron microscopy. It was found that the conductive composite films were of a “sandwich” structure, and the surfaces greatly differ in chemical compositions and phase morphologies from the bulk. The Si and N contents exhibit opposite gradient change with the measured depth of the two surface layers in the composite films, namely, the decrease in Si content and the increase in N content with increase in the depth of the surface layers. However, the N^δ+/N ratios in polypyrrole decreased with the measured depth of the conductive composite film. It was also found that the conductive composite film based on silicon crosslinked matrix exhibits more environmental stable than that based on linear matrix. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 95–101, 1999

The effects of the change of anion on the rate of hydrolysis of p-nitrophenyl diphenyl phosphate in [Cu(R-tmed)X2] and [Cu(R-tmed)(acac)X] micelles were studied at 25°C. It was found that the rate maxima of the bromide and nitrate complexes are lower than those of the chloride complexes. The effect is slightly more pronounced in the [Cu(R-tmed)X2] micelles. The pH-concentration profiles demonstrate the presence of the active copper(II)-OH species in the micelles and the kinetic results can be rationalized in terms of a multiple-equilibrium scheme which determines the concentration of the copper(II)-OH species under various conditions.

A series of long-chain piperazine derivatives,N-alkyl-N′-methyl piperazine and their amphiphilic salts,N-alkyl-N′-ethyl-N′-methyl piperazinium bromide, and the relatedN-alkyl-N,N′-dimethyl piperazinium bromide were synthesized and characterized by1H and13C NMR and FTIR spectroscopy. Under the experimental conditions used, the NMR data showed unequivocally that quaternarization ofN-alkyl-N′-methyl piperazine by the reaction with ethyl bromide occurred exclusively at the nitrogen atom bearing the methyl group due to the steric hindrance of the long-chain alkyl group attached to the other nitrogen atom. Critical micelle concentration (cmc) and surface-active properties of the amphiphiles were investigated. Plots of surface tension, γ, against log concentration were presented. At cmc, the number of molecules adsorbed at the air–water interface was found to decrease with increasing chain length. This was attributed to the increase in electrostatic repulsion within the adsorption layer as suggested by Lunkenheimeret al.(Colloids Surf. A101,197 (1995)).