Capillary Electrochromatography of Molecularly Imprinted Monolithic Column Using p-Hydroxybenzoic Acid as Templates

Moleculary imprinted polymers using p-hydroxybenzoic acid as templates wassynthesized by an in situ polymerization reaction and rendered capillary monolithic column wasused in capillary electrochromatographic mode. Good molecular recognition was achieved for p-hydroxybenzoic acid and good resolution of isomers can be realized.

STRUCTURE OF THERMOTROPIC LIQUID CRYSTALLINE VANILLIC ACID/P-HYDROXYBENZOIC ACID/ETHYLENE TEREPHTHALATE VHE TERPOLYESTERS

Thermotropic liquid crystalline VHE terpolyesters made from vanillic acid (V),p-hydroxybenzoic acid (H) and poly(ethylene terephthalate) (E) were studied by 400 MHz NMR spectra, wide angle X-ray diffraction,scanning electron and polarizing microscopes.It was found that the VHE terpolyesters had random sequence distribution.The VHE terpolyester films exhibited highly oriented fibrillar structure.

Psychopharmacological Profile of Hydroalcoholic Extract and P-Hydroxybenzoic Acid Obtained from <i>Bourreria huanita</i>(Boraginaceae) in Mice

Bourreria huanita (Lex.) Hemsl. (Boraginaceae) is a very rare and highly appreciated tree in Mesoamerica for its medicinal properties and beauty. It grows in a region extending from central Mexico to Costa Rica. Ethnobotanical surveys have shown that the infusion of dried flowers is popularly used as a tranquilizer to cure several diseases. In the present study we report the isolation of p-hydroxybenzoic acid (pHBZ) obtained from the hydroalcoholic extract (HE) of B. huanita, and the effect of both, the extract and the compound on the central nervous system in mice. HE of B. huanita (100, 150, 300 mg/kg) and pHBZ (10 mg/kg) were orally administered to mice and 1 h later, behavioral tests were performed. The effects of HE and pHBZ were tested by pentylenetetrazole (PTZ) and strychnine (STR) induced seizures, pentobarbital-induced hypnosis, the forced swimming test and the tail suspension test, the elevated plus maze, apomorphine-induced stereotypy and the climbing test, the inhibitory avoidance test and the open-field test. B. huanita extract produced hypnotic, anxiolytic and antidepressant effects in animals, with no change in motor performance. On the other hand, the extract did not reduce PTZ and STR-induced convulsions, apomorphine-induced stereotypy or climbing. Moreover, no changes were observed in the animals’ memory. The compound pHBZ was effective only in the depression tests. The results obtained in the present study suggest that B. huanita exhibited sedative, antidepressant and hypnotic activities in mice, and that the antidepressant activity may be mediated by an isolated compound identified as pHBZ.

Induced Effects of Exogenous Phenolic Acids on Allelopathy of a Wild Rice Accession(Oryza longistaminata,S37)

Four exogenous phenolic acids, including salicylic acid, fumalic acid, p-coumaric acid and p-hydroxybenzonic acid, were used to investigate the regulatory effects on allelopathy of a wild rice accession of S37 （Oryza Iongistaminata）, which is a known allelopathic rice. The four exogenous phenolic acids induced the enhancement of the allelopathic potential of wild rice S37 in target weeds though the weed-suppressive activities were low, and the inducible effects were dependent on the specific phenolic acid, concentration and treatment time. After foliar application of exogenous phenolic acids, the inhibition rates for plant height, root length and fresh weight of barnyard grass （Echinochioa crus-galli） were significantly higher than those of the control. Especially at the concentration of 100 mg/L, the inhibition rates for plant height and fresh weight of barnyard grass by fumalic acid were 38.12% and 26.31% higher than those of the control, showing that fumalic acid was more effective compared with other phenolic acids in inhibiting monocotyledon weed growth. Furthermore, the weedsuppressive activity of aqueous extract from the leaves of wild rice S37 treated with exogenous phenolic acids was increased, and it peaked at 48 h after the treatment with the aqueous extract, and then gradually declined.

INFLUENCE OF POLYMER CHARACTERISTICS AND MELT-SPINNING CONDITIONS ON THE PRODUCTION OF HIGH RANDOMNESS 60PHB/PET THERMOTROPIC LIQUID CRYSTAL COPOLYESTER FIBER

Six samples of linear high randomness 60PHB/ PET thermotropic liquid crystal copolyesters are made by melt copolymerization at 290℃ , whose randomness about 0.955 is measured by the discernible ’H-NMR spectrometer. High tenacity, high module fiber is prepared by melt spinning in liquid crystal phase. The effect of molecular weight, shear rate, temperature as well as spinning drawn ratio on the mechanical behavior of 60PHB / PET copolyester fiber are shown that, lower shear rate (2 10 s-1), higher temperature melting （300℃ ）, lower temperature spinning （280℃ ） and higher molecular weight are favourable to the increase of the fiber mechanical properties. With the variance of drawn ratio, fiber mechanical property has a transition point due to traversion from shear-orientation to drawn-orientation. The copolyester fiber has high crystallinity, high orientation at the crystalline region, high chain orientation and high regular fibrillar structure.

STUDIES ON SEQUENCE STRUCTURE OF PET/PHB COPOLYESTERS

In this paper,the sequence distribution in the copolyester made from polyethyleneterephthalate （PET） and p-hydroxybenzoic acid （PHB） at 290℃has been investigated by 400MHz 1H-NMR.It has been found that reference factor m of PET/PHB copo!yester linearly de-creases when PHB molar fraction increases.In addition,a series of sequence structure parameters,such as PET,PHB segment mean length,randomness,etc.are calculated from a probability modelby m,XPHB%.This copolyester made at 290℃ is found to be nearer to that of completely randomcopolymer compared with that of the eopolyester made at 270℃,as in the case of the generalcopolycondensation.PHB-rich phase is formed only when PHB per number≥4,basing on thisconclusion,we establish the relationship between theoretical contents of PHB-rich phaseWPHB% and PHB contents XPHB% :WPHB%=104.0XPHB4.40 The minimum PHB-rich phase con-tent forming liquid crystal phase is 1.1% wt.

RHEOLOGICAL PROPERTIES OF LIQUID CRYSTALLINE COPOLY (ρ-HYDR0XYBENZ0ATE/BISPHENOL A TEREPHTHALATE)

Various aspects of the rheological behaviour of liquid crystalline copolyesters, i.e.,samples of copoly (p-hydroxybenzoate / bisphenol A terephthalate), were explored by usingInstron capillary rheometer. The experimental results indicated that the apparent viscositywas affected significantly by shear rate, melt temperature and p-hydroxybenzoate unit con-tent. The flow activation energies △E_η are in the range of 205.1 to 74.5 kJ/mol, dependingon the shear rate of 10-1000 s^(-1), at temperature 568-603K. These copolyesters exhibit ayield phenomenon in the shear flow, and the values of yield stress decrease with increasingtemperature. It is quite unusual that the extrudate of the copolyester shows the smallerswelling ratio even than unity at the lower temperature and lower shear rates.

Supramolecular Self-assembly Formed from Cucurbit[8]uril and p-Hydroxybenzoic Acid

The binding behavior of cucurbit[8]uril(Q[8])and p-hydroxybenzoic acid(p-HBA)has been investigated using ^(1)H NMR titration experiments,UV-Vis absorption,isothermal titration calorimetry(ITC),and X-ray crystallography.Results revealed that the Q[8]can accommodate two p-HBA molecules to form a 1:2 host-guest inclusion complex in solution,namely(p-HBA)2@Q[8].From a poorly scattering crystal,we were able to identify two symmetry unique Q[8]rings,but with different p-HBA fillings.The structure can be represented as Q[8]+1.5 p-HBA,which gives Q[8]@(p-HBA)2∙Q[8]@p-HBA as the structural formula.This supramolecular structure was screened for its ability to capture iodine.The experimental results showed that the adsorption efficiency of the supramolecular organic framework material for iodine capture was 43.8%,with an equilibrium adsorption capacity of 223.3 mg/g.

Grafting of MIPs from PVDF Membranes via Reversible Addition-fragmentation Chain Transfer Polymerization for Selective Removal of p-Hydroxybenzoic Acid

Effective molecularly imprinted membranes（MIMs） were developed as an efficient adsorbent for the selective removal ofp-hydroxybenzoic acid（p-HB） from acetylsalicylic acid（ASA, aspirin）. The MIMs were grafted successfully from poly（vinylidene fluoride） microfiltration membranes via reversible addition-fragmentation chain transfer（RAFT） polymerization. The graft copolymerization of acrylic acid（AA） in the presence of template p-hydroxybenzoic acid led to molecularly imprinted polymer（MIP） film coated membranes. The obtained MIMs were characterized by scanning electron microscopy（SEM）, Fourier transform infrared spectrophotometer（FTIR） and Raman spectra, and batch mode adsorption studies were carried ont to investigate the specific adsorption equilibrium, kinetics and selective recognition properties of different MIMs. The kinetic properties of the MIMs could be well described by the pseudo-second-order rate equation. Selective permeation experiments were performed to evaluate the permeation selectivity of the p-HB imprinted membranes. The observed performances of the MIMs are applicable to the further purification of aspirin. Keywords Acetylsalicylic acid; Reversible addition-fragmentation chain transfer; Molecularly imprinted membrane; p-Hydroxybenzoic acid; Selective adsorption