Fabrication of chitosan/silica hybrid coating on AZ31 Mg alloy for orthopaedic applications

Biocompatible conversion of chitosan and chitosan/silica hybrid coating were prepared to enhance the biocompatibility and corrosion resistance of biodegradable AZ31 Mg alloy. The coatings were optimized and analysed with potentiodynamic polarization, SEM, ATR-IR and XPS studies. Potentiodynamic polarization studies, revealed that the coatings exhibited high corrosion resistance. The surface morphology of the Ch-3/Si coating showed small globular rough structure. The presence of functional groups was confirmed by ATR-IR. For a better understanding of chitosan/silica hybrid coating, the chemical states were examined by XPS studies. The in-vitro bioactivity of the coated samples was evaluated in Earle’s solution, which formed a dense layer of coral-like structure and calcium-deficient apatite with less stoichiometric ratio than the hydroxyapatite. In-vitro cell culture studies exhibited a good cell proliferation rate and the fabricated Ch-3/Si coating was found to be non-hemolytic. The bacterial studies proved that Ch-3/Si coating possessed inherent antibacterial activity.

THE STRUCTURE AND PROPERTIES OF CHITOSAN/POLYETHYLENE GLYCOL/SILICA TERNARY HYBRID ORGANIC-INORGANIC FILMS

The ternary hybrid films consisting of chitosan(CS),polyethylene glycol(PEG)and nano-sized silica which was surface-modified by amino groups(RNSA)were prepared.The structures of the blend membranes were characterized by attenuation total reflection-infrared spectroscopy(ATR-IR),X-ray diffraction(XRD),optical microscopy(OM)and differential scanning calorimetry(DSC).The results showed that the addition of silica affected not only the distribution and crystallinity of PEG on the sample surface,but also the ...

Preparation and Characterization of Magnetic Resin Made from Chitosan and Cerium

In this study,the water-based ferromagnetic fluid and magnetic resin made from chitosan and cerium complex(MRCCC)were successfully prepared by using the chemical co-precipitation technique and by the reversed-phase suspension cross-linkingpolymerization.MRCCC presented uniform and narrow particle size distribution as determined by the Laser Particles Sizer.TheInductively Coupled Plasma-Atomic Emission Spectrometry(ICP-AES),Fourier transform infrared spectroscopy(FT-IR),differen-tial scanning calorimetry(DSC)and X-ray powder diffraction(XRD)study demonstrated that there were iron and cerium existing inMRCCC.The movement of MRCCC under magnetic field proved its magnetic property.The swelling kinetics in water or solutionswith different pH indicated that MRCCC could be applied in solutions with pH greater than 1.0.The ferromagnetic fluid particleswere stable in MRCCC soaked in solutions with pH>2.0.In view of these results,MRCCC can be used as material for separation,clarification,adsorption,sustained release and hydrolysis activity.

Laccase biosensor using magnetic multiwalled carbon nanotubes and chitosan/silica hybrid membrane modified magnetic carbon paste electrode

A simple and rapid strategy to construct laccase biosensor for determination of catechol was investigated. Magnetic multiwalled carbon nanotubes (MMCNT) which possess excellent capability of electron transfer were prepared by chemical coprecipitation method. Scanning electron microscope (SEM) and vibrating sample magnetometer (VSM) were used to identify its surfacetopography and magnetization, respectively. Laccase was immobilized on the MMCNT modified magnetic carbon paste electrode by the aid of chitosan/silica (CS) hybrid membrane. Using current-time detection method, the biosensor shows a linear response related to the concentration of catechol in the range from 10-7 to 0.165×10-3 mol/L. The corresponding detection limit is 3.34×10-8 mol/L based on signal-to-noise ratios (S/N) ≥3 under the optimized conditions. In addition, its response current retains 90% of the original after being stored for 45 d. The results indicate that this proposed strategy can be expected to develop other enzyme-based biosensors.

TRIMETHYLSILYLATED SILICA AS RHEOLOGY MODIFIER FOR SILICONE RESINS

Trimethylsilylated silica was synthesized through hydrolytic condensation of tetraethoxysilane followed bytrimethylsilylation. Rheological properties of the silicone resin with trimethylsilylated silica as modifier were studied. Itturned out that the particle size of silica was important to the rheological behavior of the modified resin. Trimethylsilylatedsilica of medium particle size shows the strongest tendency of forming physical network in the resin.

RHEOLOGICAL MODIFICATION OF EPOXY RESINS WITH NANO SILICA PREPARED BY THE SOL-GEL PROCESS

Nano silica-modified epoxy resins were synthesized by the sol-gel process. The materials have themorphological structure of nano particales dispersed in the epoxy matrix. The dispersed phase formed aphysical network in the resin and thus influenced the rheological behavior greatly. However, the nano silicadid not show a significant influence on the mechanical properties of the cured resins.

Cr(VI) Removal from Aqueous Solution by Chitosan/Carboxylmethyl Cellulose/Silica Hybrid Membrane

In the present study, chitosan/carboxymethyl cellulose/silica hybrid membrane (CS/CMC/Silica) was prepared by using chitosan and carboxymethyl cellulose in the presence of 3-glycidoxypro- pyltrimethoxysilane (GPTMS) as the crosslinking agent and used to remove Cr(VI) iron in effluent. The structure of CS/CMC/Silica hybrid membrane was characterized by FT-IR spectroscopy and scanning electron microscopy (SEM). The influence of Cr(VI) concentration, solution temperature, and pH, adsorption time on adsorption performance of hybrid membrane was investigated. Adsorption capacity increased with the increase of Cr(VI) concentration and absorbing time, and decreased with the increase of sorbent dosage and temperature. The adsorption equilibrium of Cr(VI) ion was attained within 60min of contact. The pseudo-second-order model fitted the kinetic data well.

Adsorption characteristics of thorium on silica-based anion exchange resins

To isolate and separate thorium from nitric acid solutions, three silica-based anion exchange resins were synthesized. Batch experiments were carried out to investigate adsorption behavior of thorium in nitric acid solutions. Adsorption at different concentrations of nitric acid and thorium, influence of contact time and coexisting metal ions, and effect of NO3– were investigated in detail. It was found that at high HNO3 concentrations,the resins exhibited higher adsorption capacity and better affinity towards thorium. The adsorption kinetics could be described by the pseudo-second order model equation, while the adsorption isotherms were well correlated by the Langmuir model. The maximum capacity towards thorium species on SiPyR-N4 was evaluated at 27–28 mg/g-resin. The thermodynamic parameters indicated the adsorption was an exothermic reaction. The presence of NO3– was found to promote the retention of the thorium species.

Silica-supported Macroporous Chitosan Bead for Affinity Purification of Trypsin Inhibitor

Macroporous cross-linking chitosan layer coated on silica gel (CTS-SiO2) was prepared by phase inversion and polyethylene glycol (PEG) molecular imprinting methods. Formation of macroporous surface was investigated by scanning electron microscopy (SEM) and BET analysis. The prepared bead was activated by reacting with 1,2-ethylene diglycidyl ether for introducing epoxy groups, and trypsin could be efficiently immobilized on the bead as a biospecific ligand. The bead bearing trypsin was employed to purify trypsin inhibitor (TIs) from egg white as affinity adsorbent.

THE EFFECT OF MEDIUM ON ADSORPTION OF FREE ACID BY CROSSLINKED CHITOSAN RESIN

The adsorption of free acid of low concentration by crosslinked chitosan resin was followed by electrochemical experimental technique. The effect of acid concentration and the media on adsorption was discussed. The experimental results show that both the apparent rate constant and the interaction energy between the adsorbent and adsorbate are decreased while the concentration of hydrochloric acid is increased. In the adsorption system, the adsorption was effected by addition of organic solvent.

Controlled Release of Diclofenac Sodium from Silica-Chitosan Composites

The release profiles of acidic form of diclofenac sodium adsorbed on mesoporous silicas (Silochrom and two samples of spherical silicas) were compared with the dissolution characteristics of the pure drug. Desorption of diclofenac sodium from impregnated silicas with various surface liophilicity and composites of silica with chitosan have been studied using rotating basket method in phosphate buffer, pH 6.8. Sedimentations of sodium diclofenac via adsorption and impregnation from alcohol solution on fumed silica and modified silicas with grafted aminopropyl and trimethylsilyl groups were carried out. Polymer-containing composites have been prepared by capsulation of silica particles with impregnated diclofenac sodium by protonated and deprotonated forms of chitosan. Effect of the silica surface nature on the active substance release rate was ascertained. Significant prolongation of diclofenac sodium release was detected in the case of application of hydrophobic silica as a carrier and protonated chitosan as a polymeric shell.

ADSORPTION SELECTIVITY FOR Cu^(2+),Ni^(2+),Co^(2+)IONS USING CROSSLINKING CHITOSAN RESINS IMPRINTED BY METAL IONS

Metal ion-imprintedly crosslinked chitosan resin 1 and resin 2 were prepared by theuse of Cu2+ and Ni2+ as template ions and glutaraldehyde as crosslinking agent, respectively.Through investigation on the adsorption capacities and binding constants for Cu2+, Ni2+andCo2+ ions on chitosan resins, resin 1 and resin 2 exhibit the adsorption selectivity for themixture solution of 1:1 Cu2+ and Ni2+ ions. The adsorption selectivity of metal ion-imprintedresins for their template ions is much higher than that of uncrosslinked chitosan resin.

Evaluation study on properties of a macroporous silica-based CMPO extraction resin to be used forminor actinides separation from high level liquid waste

Basic properties of a silica-based octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide (CMPO) extraction resin (CMPO/SiO2-P) was investigated.Adsorption behavior for some rare earth elements (RE) which are constituents of high level liquid waste (HLLW) and the long-term stability of the extraction resin in nitric acid solution were examined.The CMPO extraction resin was significantly stable in 3 mol·L?1 HNO3 solution at 50oC.Furthermore,the RE(III) were efficiently separated from non-adsorptive fission product (FP) elements such as Sr(II) in a column experiment using a highly nitric acid solution.The separation behaviors of the elements are considered to result from the difference in their adsorption and elution selectivity based on the complex formation with CMPO.There was no strong dependency of RE(III) separation efficiency on feed solution flow rate.Only from the perspectives of the acid-resistant behavior of CMPO extraction resin and the elution kinetics for the metal ions with the extraction resin,the CMPO extraction resin can be used in the modified MAREC process for HLLW partitioning.

STUDIES ON THE SYNTHESES AND PROPERTIES OFSNAKE-CAGE TYPE CHELATE RESINS I System of Carboxymethyl-chitosan/B-62/Triethylenetetramine

Using carboxymethyl chitosan （CM-CTS） as snake resin, B-62 resin crosslinked by,triethylenetetramine （TETA） as cage resin, a series of novel snake-cage type resin weresynthesized. Such factors as the best synthetic conditions, the swelling and regenerationproperties, and the sorption capacities of the above mentioned resins for metal ions wereinvestigated. The experimental results show these resins have good swelling propertiesand mechanical stability and do not run off in organic and inorganic solvents. Thesorption capacities of them for Cu2+, Ni2+,Zn2+, and Pb2+ were 0.89, 0.54, 0.32, and0.22mmol/g, respectively.

壳聚糖-SiO_(2)气凝胶/纤维素/聚丙烯复合水刺材料的制备及其吸附染料性能

为制备用于有机染料废水处理的生物质材料,以纤维素纤维/聚丙烯(CF/PP)为基材,经氧化后与以壳聚糖(CS)和硅酸四乙酯(TEOS)为原料制备的CS-SiO_(2)混合溶液进行反应,再通过冷冻干燥得到CS-SiO_(2)气凝胶/氧化纤维素(OCF)/PP复合水刺非织造材料。对复合材料的形貌、结构和其对有机染料吸附性能进行测试与表征,结果表明:相较于CF/PP水刺非织造材料,CS-SiO_(2)气凝胶/OCF/PP复合水刺非织造材料表面出现明显的微孔结构,在OCF/PP水刺非织造材料表面出现了归属于CS和SiO_(2)的红外特征峰;当TEOS体积分数为25%时,制得的样品在30℃、pH值为7的条件下对亚甲基蓝(MB)的吸附效率可达99.63%,经5次重复使用后,其对MB的吸附效率仍保持在80.59%左右;相比于CF/PP水刺非织造材料,CS-SiO_(2)气凝胶/OCF/PP复合水刺非织造材料的拉伸强度和断裂伸长率略有下降。

消光材料研究进展

消光材料是一种具有削弱光线作用的材料。由于消光材料具有优异的消光性能,因此广泛应用于需要表面呈现哑光效果的场景中。通过对消光材料的种类进行分类介绍,详细地对无机消光材料、有机消光材料和生物消光材料进行综述。对于生物消光材料侧重于考察可见光消光和红外消光两个方面的性能。生物消光材料因其环保无污染的特性,并且在可见光和红外消光方面具有优势,将会主导绿色消光材料的发展趋势。

P(AMPS-co-AM)/羧甲基壳聚糖/蒙脱土高吸水树脂的合成

采用水溶液聚合法合成了P(AMPS-co-AM)/羧甲基壳聚糖/蒙脱土高吸水树脂。通过傅立叶变换红外光谱和扫描电子显微镜进行了表征。研究了引发剂、交联剂、羧甲基壳聚糖、有机化蒙脱土用量以及AMPS与AM的投料比对高吸水树脂吸水性能的影响。结果表明,最佳合成条件为m(AMPS):m(AM)=1:1.5,6%CMCTS,1.5%OMMT,0.8%KPS,0.15%MBA。树脂在最佳性能下吸水率达567倍,吸盐水率达104倍,25℃下12 h的保水率达68.1%。

不同界面剂对湿接缝混凝土黏结性能影响

为研究界面剂对湿接缝黏结性能的影响,首先通过力学性能试验,确定硅灰水泥净浆界面剂中硅灰的最佳掺量,再通过劈裂抗拉强度试验、三点弯曲试验和抗剪强度试验,探究普通水泥净浆、硅灰最佳掺量下的水泥净浆、环氧树脂作为界面剂时,对湿接缝黏结性能的影响效果。结果表明:硅灰最佳掺量为8%时水泥净浆力学性能最优,从抗拉角度和抗剪角度进行分析,不同界面剂对湿接缝黏结性能的影响,由大到小排序均为:环氧树脂界面剂>掺8%硅灰水泥净浆界面剂>普通水泥净浆界面剂>无界面剂。可见,普通水泥净浆界面剂对湿接缝黏结性能提升较小,而环氧树脂界面剂和掺8%硅灰水泥净浆界面剂对湿接缝黏结性能提升效果较为明显。

高渗透性注浆材料渗透能力对比试验分析

为探究不同高渗透性注浆材料渗透能力的大小,以超细水泥、脲醛树脂、硅溶胶3种材料为研究对象,设计了室内无压河砂介质及有压黏土介质注浆试验,根据注浆后两种介质中的固结体几何形状及裂隙发育程度,分析3种材料的孔内渗透能力强弱及扩散机制。结果表明,3种材料中,硅溶胶孔内渗透能力最强,脲醛树脂次之,超细水泥最小,且随着介质渗透性降低,其扩散方式由孔内渗流向劈裂裂隙管道流转变,浆液渗透能力越弱,这一过程转变的越快。