脂质氧化产物-蛋白质相互作用研究进展

富含不饱和脂质的食品及其原料在加工和储存过程中易受多种因素影响而发生氧化。在此过程中生成的过氧化自由基和其他次级氧化产物能使蛋白质发生复杂变化。脂质氧化产物与蛋白质相互作用可以诱发蛋白质的交联、聚合,导致蛋白质共价结构变化、功能特性下降、风味恶化及营养损失,甚至产生有毒有害物质。脂质氧化产物诱导的蛋白质氧化会造成色氨酸、精氨酸、酪氨酸等氨基酸含量减少;巯基含量增加、可溶性蛋白质的表面疏水性降低;α-螺旋、β-折叠增加;蛋白质聚集形成粒径较大的高分子聚集体。本文综述了脂质氧化产物-蛋白质相互作用及其对蛋白质结构和功能特性的影响,以期对揭示脂质氧化产物与蛋白质的互作机制具有指导意义。

Crosslink Polymerization Kinetics and Mechanism of Hydrogels Composed of Acrylic Acid and 2-Acrylamido-2-methylpropane Sulfonic Acid

Crosslink polymerization kinetics of poly（acrylic acid-co-2-acrylamido-2-methylpropane sulfonic acid）,AA/AMPS hydrogels,was investigated by using dilatometry in the presence of sodium persulfate as initiator and N,N＇-methylene bis（acrylamide） as crosslinker.It was found that the reaction for the crosslink polymerization of AA/AMPS hydrogels had orders of 0.58,1.14,and 0.86 with respect to the initiator,AMPS,and AA,respectively.From the Arrhenius plots,the activation energy of the crosslink polymerization was found to be about 140 and 89 kJ·mol-1 in the presence and absence of the crosslinker,respectively,in the temperature range from 45 to 65 °C.It was noted that the crosslinker had effects on the reaction order of the initiator and the activation energy due to the formation of cross-linked networks,which was verified by Fourier transfer infrared （FTIR） spectrum.To further confirm the influences of the cross-linked network structure on kinetic parameters of the crosslink polymerization,a mechanism was proposed,which highlights the different termination routes between free radical polymerization and crosslink polymerization.These results suggest that dilatometry provides a convenient tool for crosslink polymeri-zation study,and confirm that the cross-linked networks are formed in the crosslink polymerization.

Preparation and Dyeing Performance of a Novel Crosslinking Polymeric Dye Containing Flavone Moiety

A yellow crosslinking polymeric dye was prepared by grafting the flavone moiety containing azo chromophore onto polyvinylamine backbone.The λ max of this polymeric dye in water is 382 nm.The polymeric dye is fixed to silk and cotton with a crosslinking agent,2-chloro-4,6-di(aminobenzene-4'-β-sulphatoethylsulphone)-1,3,5-s-triazine,which acts as a bridge between the fiber and dye molecules.The fixation of this polymeric dye reaches 99% and the dyed samples exhibit excellent rubbing and washing fastness.

Deformation of Linked Polymer Coils

Linked polymer solution (LPS) is defined as the solution of linked polymer coils (LPCs) dispersed in water, composed of low concentration partially hydrolyzed polyacrylamide (HPAM) and aluminum citrate (crosslinker). In the work, the conformational changes of LPCs under different conditions were investigated by the methods of membrane filtering under low pressure, dynamic light scattering and core flooding experiments. The results showed that in some conditions the LPCs could be compressed mechanically to 1/158.5 of their original volume because of relatively lower HPAM cross-linking. The hydration property of LPCs was similar to that of normal polymer coils. The deformation of LPCs was more restricted than that of ordinary polymer coils under the flow shear stress or the shift of hydration equilibrium caused in the variation of the electrolyte concentration which is responsible for the effective plugging in the throats of porous media when LPCs are used for deep diverting.

Adsorption of catechol from aqueous solution by aminated hypercrosslinked polymers

Adsorption of catechol from aqueous solution with the hypercrosslinked polymeric adsorbent NDA-100 and its derivatives AH-1, AH-2 and AH-3 aminated by dimethylamine, the commercial resin Amberlite XAD-4 and weakly basic anion exchanger resin D301 was compared. It was found that the aminated hypercrosslinked resins had the highest adsorption capacities among the tested polymers. The empirical Freundlich equation was successfully employed to describe the adsorption process. Specific surface area and micropore structure of the adsorbent, in company with tertiary amino groups on matrix affected the adsorption performance towards catechol. In addition, thermodynamic study was carried out to interpret the adsorption mechanism. Kinetic study testified that the tertiary amino groups on the polymer matrix could decrease the adsorption rate and increase the adsorption apparent activation energy.

Synthesis and Characterization of Suspension Polymerized Styrene-Divinylbenzene Porous Microsphere Using as Slow-Release-Active Carrier

Functional porous microspheres used for the slow release carrier of actives in cosmetics or pharmaceuticals were prepared by modified suspension polymerization of styrene （ST） with divinylbenzene （DVB） in the presence of toluene, cyclohexanol and heptane as porogenic diluents. The use of ultrasonic dispersion decreases the beads＇ size and improves the uniformity. The effects of the porogen mixture, DVB content and solvent extraction on the surface performance of the synthesized beads were studied. The microspheres were characterized by scanning electron microscopy （SEM） and BET surface area determination. It was found that a great proportion of the non-solvating porogen increases the pore diameter and the specific surface area. High DVB concentration also results in the great specific surface area and porosity. When the ratio of toluene/cyclohexanol is 1：2, DVB content is at the range of 40%-60% and methylene chloride was used as extractant, the beads with good spherical shape and pore size were obtained. The prepared porous microspheres were applied as active carriers and showed satisfactory slow release effect. Over 10h constantly sustained release was observed in vitro releasing test for hydroquinone-loaded microspheres. Great surface area promoted high concentration of released hydroquinone.

ADSORPTION OF PHENOL AND NITROPHENOLS ON A HYPERCROSSLINKED POLYMERIC ADSORBENT

The adsorption of phenol and nitrophenols on hypercrosslinked polymeric adsorbent was studied as a function of the solution concentration and temperature. Adsorption isotherms of phenol and nitrophenols on hypercrosslinked resin were determined. These isotherms were modeled according to the Freundlich adsorption isotherm. The isotherms for phenol and nitrophenols on hypercrosslinked resin were assigned as L curves. Thermodynamic parameters were calculated for all phenol and nitrophenols. The kinetics experiment results showed that the adsorption rates were of the first-order kinetics. The rate constants at 303K were calculated.

COMPATIBILITY OF POLY (STYRENE-B-2-VINYL PYRIDINE)/IONOMER BLENDS BASED ON ION-LIGAND INTERACTION

In this work, DSC and SEM studies indicate that ion-ligand interaction can be utilized to enhance the interaction of poly (styrene-block-2-vinyl pyridine)[P (S-b-2VP)] and polyethylene based ionomer (Surlyn). The compatibility for this blending system can be improved by this special interaction and 20/80 wt is the optimum blending composition with good compatibility. FTIR results further certify that strong interactions exist in the blending system.

Study on Sythesis of Crosslinked Chitosan Prolymer and Its Use in the Removal of Urea

A novel bead form of ploymer of high sorption capacity for urea were obtained by the reaction of glutaric dialdehyde wigh chitosan dispersed in acetic acid solution. The sorption capacity reached ￣ 82.0 mg / g sorbent at 37℃ and pH 7.4 The concentration of urea in the buffer solution was 1300 mg/ L. The sorption of urea was related to the degree of crosslinking of the sorbent, concentration ofurea, ionic strength and temperature.

Study on effect of feed ratio on controlled cross-linking polymerization process

A controlled cross-linking polymerization containing intra- and intermolecular reactions was designed based on random coil morphology of macromolecules in solution. The soluble intramolecular cross-linked maeromolecule （ICM） was successfully synthesized in the system with PVA and MDI. We found an especial dissolving phenomenon, namely the semi-soluble phenomenon when some gels dissolved in DMF. The chain growth process of ICMs was investigated by Transmission electron microscopy （TEM） pictures of samples at different reacting times, in addition, TEM pictures show ICMs have three kinds of styles in structure, viz. ＂globule structure＂, ＂nubby structure＂ and the intervenient between the above two structures, and the efflux time of the ICMs was measured by an Ubbelohde viscosimeter, it was found that the efflux time decreases with the degree ofcrosslink increasing.

TREATMENT OF SORBIC ACID MANUFACTURING WASTEWATER BY HYPERCROSSLINKED POLYMERIC ADSORBENT (NDA-150)

The treatment of sorbic acid manufacturing wastewater by NDA-150 resin was investigated. The experiments show that this process is suitable for the treatment of sorbic acid manufacturing wastewater. About 98% sorbic acid and 50% CODcr were removed under optimal operating conditions, and 70% of sorbic acid in sorbic acid manufacturing wastewater was reclaimed. This process makes it possible to recover valuable materials from the wastewater and to improve the quality of effluent water.

Synthesis of crosslinked polystyrene particles by seeded batch polymerization with monomer absorption

A highly crosslinked, monodispersed polystyrene（PS） particle was prepared by a seeded batch dispersion polymerization with a monomer absorption method. Prior to polymerization, 1,9 lam monodispersed PS seed particles were treated under an optimum condition of monomer absorption. The effects of divinylbenzebe（DVB） concentration and polymerization temperature were examined for styrene（in PS seed）/styrene（in the second stage） mass ratio of 1：1 in the medium range of EtOH/water mass ratio of 100/0-80/20 and 2.3 μm uniform crosslinked PS particles containing 15%-20% （mass fraction） DVB were prepared at 60-70 ℃. The results show that monomer absorption before the second stage of polymerization is more effective to prepare highly crosslinked monodispersed PS particles.

MICROLEAKAGE OF CLASS V RESIN-MODIFIED GLASS IONOMER CEMENT AND COMPOMER RESTORATIONS IN VITRO

Objective To assess the microleakage of Class V restorations made with two resin-modified glass ionomer cements （RMGICs） and two polyacid-modified composite resins （PMCRs）. Methods Restorations of the four materials （ GC Fuji Ⅱ LC, Vitremer^TM, Dyract AP and F2000^TM ） were placed in facial Class V cavity preparations in forty noncarious human molar teeth. Teeth were randomly assigned to 4 experimental groups of 10 teeth each. After thermal cycling（ ×20, 5 -55℃ ） , the interface between dentin and restorations was spattercoated with gold and observed under scanning electron microscopy （SEM）. Then the square and average width of margin gaps of central 1/3 interface were recorded with image analysis software. Results The data indicated no significant differences between all the restorative materials for both occlusal and gingival margins. Further analysis revealed there were statistically significant differences between occlusal margins and gingival margins for VitremerTM and Dyract AP, respectively. Conclusion None of the tested materials guaranteed margins free of microleakage. Resin-modified glass ionomer cements showed similar margin gaps to the polyacid-modified composite resins tested.

Development and Construction of 345 kV Power-Optical Fiber Composite XLPE 2,500 mm2 with Prefabricated Joint

Due to the increasing demand of replacing large capacity overhead lines with underground cables in Korea, KEPCO （Korea Electric Power Corporation） and LS Cable （LS Cable ＆ System） have developed 345 kV optical fiber composite XLPE （cross-linked polyethylene） 2,500 mm2 cable system. This system has been installed in Cheongna district of Incheon city. KEPCO and LS Cable are also planning to build the cooling system in a tunnel in order to reduce the ambient temperature caused by currents. In this paper, the process of development, field installation, and final inspection test of the complete system will be described.

Two Organic Phase Suspension Polymerization for Novel Hypercrosslinked Resin Bead by Polycondensation of CMB

The suspension polymerization with two organic phases was adopted to prepare spherical hyper- crosslinked resin by self-polycondensation of 4,4＇-bis-（chloromethyl）- 1, 1＇-biphenyl （CMB）. The chemical structure,morphology and pore characteristics of the novel spherical resin were characterized with Fourier transform infrared spectroscopy （FTIR）, micrograph and Brunauer-Emmett-Teller （BET）. It is found that the suspension system and stirring speed impose a great influence upon the regularity and size distribution of hypercrosslinked beads. To prepare CMB resin beads with diameter of about 300 μm, the optimal condition is as follows： stirring speed 300 r·min^-1, and the volume ratio of the two organic phases （nitrobenzene/dimethyl silicon oil） 1 ： 5. After the self-polycondensation and sqccedent post-crosslinking of CMB monomer, the spherical adsorbent presents high spec^al surface area （1190 m^2· g^-1） and abundant pore^volume （0.714 cm^3· g^-1）, and could be potentially applied qn the adsorption of various organic molecules and synthesis of porous ion exchanger.

Conjugated microporous polymers for near-infrared photothermal control of shape change

Herein,a facile and highly efficient synthetic method to prepare organic photothermal materials with high photo-stability and outstanding photothermal performance is reported.Through direct polymerization of commercial aromatic monomers in the presence of anhydrous aluminium chloride and dichloromethane,four kinds of conjugated microporous polymers(CMPs)were obtained.Detailed structural analysis confirmed that the resultant CMPs possessed abundant micropores with an extendedπ-conjugated skeleton.Under near-infrared(NIR)light irradiation(808 nm,1.0 W cm−2),all the CMPs showed fast heating-up behavior with their maximum temperatures higher than 150℃.Moreover,the efficiency of photothermal conversion(η)of the CMPs was found to increase linearly with the increase in the number of conjugated benzene rings within the monomer.Poly-TPE from tetraphenylethylene(TPE)and Poly-TP from o-terphenyl(TP)showed highηvalues of over 47%.Poly-TPE was additionally used as a photothermal filler to remotely and spatially control the shape recovery of thermal-sensitive shape memory polymers(SMPs),while its introduction(1 wt%)had little influence on the thermal and mechanical properties of the polymer matrixes.Owing to their excellent NIR photothermal performance as well as a one-step synthetic preparation,these CMPs may be promising photothermal materials for practical applications.

Surface-imprinted polymers in microfluidic devices

Molecularly imprinted polymers are generated by curing a cross-linked polymer in the presence of a template. During the curing process, noncovalent bonds form between the polymer and the template. The interaction sites for the noncovalent bonds become "frozen" in the cross-linking polymer and maintain their shape even after the template is removed. The resulting cavities reproduce the size and shape of the template and can selectively reincorporate the template when a mixture containing it flows over the imprinted surface. In the last few decades the field of molecular imprinting has evolved from being able to selectively capture only small molecules to dealing with all kinds of samples. Molecularly imprinted polymers (MIPs) have been generated for analytes as diverse as metal ions, drug molecules, environmental pollutants, proteins and viruses to entire cells. We review here the relatively new field of surface imprinting, which creates imprints of large, biologically relevant templates. The traditional bulk imprinting, where a template is simply added to a prepolymer before curing, cannot be applied if the analyte is too large to diffuse from the cured polymer. Special methods must be used to generate binding sites only on a surface. Those techniques have solved crucial problems in separation science as well as chemical and biochemical sensing. The implementation of imprinted polymers into microfluidic chips has greatly improved the applicability of microfluidics. We present the latest advances and different approaches of surface imprinting and their applications for microfluidic devices.

Improved biocompatibility of phosphorylcholine end-capped poly(butylene succinate)

In this work, the biocompatibility of a biomimetic, fully biodegradable ionomer phosphorylcholine (PC)-functionalized poly(butylene succinate) (PBS-PC) was investigated by means of hemolysis, platelet adhesion, protein adsorption and cytotox- icity experiments. The reference materials were poly(butylene succinate) (PBS) and chloroethylphosphoryl functionalized poly(butylene succinate) (PBS-Cl). The hemolysis rates (HR) of the leaching solutions of PBS, PBS-Cl and PBS-PC were all lower than the safe value, and the rate of PBS-PC was reduced to 1.07%. Scanning electron microscopy (SEM) measurements showed that platelet adhesion and aggregation were significant on both PBS and PBS-Cl surface. In contrast, very few platelets were observed on PBS-PC surface. Bicinchoninic acid (BCA) measurements revealed that the adsorption amounts of bovine serum albumin (BSA) and bovine plasma fibrinogen (BPF) on PBS-PC surface were 52% and 72% reduction respectively compared with those on PBS surface. Moreover, non-cytotoxicity of both PBS-PC particles and its leaching solution was sug- gested by MTT assay using mouse L929 fibroblast cells. All the results demonstrated that the biocompatibility of PBS could be greatly improved by PC end-capping strategy. This PC functionalized polyester may have potential applications in biological environments as a novel carrier for controlled drug release and scaffold for tissue engineering.

Physio-and chemo-dual crosslinking toward thermoand photo-response of azobenzene-containing liquid crystalline polyester

Combining the stability of chemical crosslinking and the processability of physical crosslinking is a well-established strategy to design new materials with desirable stimuli–responsive properties. Herein, a series of azobenzenebased thermotropic liquid crystalline polyesters were synthesized by introducing mesogenic dial named 4,4＇-bis（6-hydroxyhexyloxy）azobenzene（BHHAB）, 2-phenylsuccinic acid（PSA）, and different contents of 1,2,3-propanetricarboxylic acid（PTA） as the chemical crosslinker. All these polyesters showed good thermal stability and smectic liquid crystalline phase. Wide-angel X-ray diffraction（WAXD） and the fluorescence emission spectra confirmed the existence of π–πstacking interactions as the physical crosslinking in the polymer chains, particularly at the lower content of PTA. However, when the PTA content increased, the chemical crosslinking changed the chain conformation, and thus the intensity of physical crosslinking slackened gradually. Combining the physical and chemical crosslinking, these polyesters showed the thermoplastic processability, thermal shape memory, heat-assisted healing and photoresponsive behaviors. Taking advantages of these features, these multiple stimuli–responsive polymers can bring more chances for smart materials such as soft actuator.

Porous polymer supported palladium catalyst for cross coupling reactions with high activity and recyclability

Porous polymer supported palladium catalyst for cross coupling reactions with high activity has been successfully prepared by coordination of Pd 2+ species with Schiff bases functionalized porous polymer. The catalyst has been systemically investi-gated by a series of characterizations such as TEM, N 2 adsorption, NMR, IR, XPS, etc. TEM and N 2 isotherms show that the sample maintains the nanoporous structure after the modification and coordination. XPS results show that chemical state of palladium species in the catalyst is mainly +2. More importantly, the catalyst shows very high activities and excellent recycla-bility in a series of coupling reactions including Suzuki, Sonogashira, and Heck reactions. Hot filtration and poison of catalysts experiments have also been performed and the results indicate that soluble active species (mainly Pd(0) species) in-situ gener-ated from the catalyst under the reaction conditions are the active intermediates, which would redeposit to the supporter after the reactions.