Research of Inclusion Complexation of 4,4＇-Thiodiphenol Effected by β-Cyclodextrin in Aqueous Solutions and the Effect on Photodegradation

The inclusion behavior of 4, 4＇ -Thiodiphenol （TDP）, a typical bisphenol and endocrine disruptor, reacts with β-cyclodextrin （β-CD） in aqueous solutions has been investigated by means of UV absorption spectrum and quantum-chemical calculation with Gaussian 98 software. The results show that the inclusion behavior of TDP is quite different in acidic solutions （pH 5.9） from that in alkaline solutions （pH 10.0）. This behavior difference is attributed to the different formula structures in aqueous solutions at acidic and alkaline pH values that are demonstrated by quantum- chemical modeling and calculation. TDP forms a 1 ： 1 fl-CD inclusion complex in aqueous solutions. The equiiibrium constant K was calculated to be 553.49 L/mol at pH 5.9 and 1 318.20 L/mol at pH 10.0 respectively for the inclusion complex reaction by using the modified Benesi-Heldbrand equation. After inclusion TDP＇s structure is changed especially at the inclusion part with the bond order becoming larger, which results in inhibitive photodegradation during direct photooxidation and H2O2 assisted photooxidation.     

Formation of the Inclusion Complex of Orange II with β-Cyclodextrin and Its Photostability

Inclusion complex of Orange II with β-Cyclodextrin (β-CD) and the anti-photolysis effect under UV-light were investigated. The molar ratio of inclusion complex of β-Cyclodextrin and Orange Ⅱ is 1∶1. The formation constant K=1.236×103 L/mol was determined by the UV and Fluorescence spectra respectively, which was quite in accordance with the calculation with a modified Benesi-Hildbrand equation. The inclusion complex was characterized by the IR spectra and the molar ratio of inclusion complex is 1∶1 too. The formation constant K=1.266×103 L/mol was determined by 1 H NMR analysis and was nearly the same by UV and fluorescence spectra. The photocatalytic decolorization rate of Orange Ⅱ solutions containing β-CD and TiO2 was smaller by 51.9% than that of the Orange Ⅱ solutions only containing TiO2, while in the case of direct photolysis of Orange Ⅱ solutions, β-CD can lower the photolysis rate by 48.1% under UV-light. This result indicates β-CD can inhibit the photolysis and photocatalytic decolorization of Orange Ⅱ under UV-light. The β-CD inclusion complex was found to be persistent to UV-light photolysis.     

Preparation,Characterization and Antioxidant Activity of Inclusion Complex of Bakuchiol with Hydroxypropyl-β-cyclodextrin

Bakuchiol isolated from Psoralea corylifolia is a naturally occurring prenylated phenolic monoterpene with a variety of bioactivities. The aim of this study was to improve the water solubility and thermal stability of bakuchiol through complexing it with hydroxypropyl-β-cyclodextrin(HP-β-CD). The bakuchiol/HP-β-CD inclusion complex's behavior and characterization were investigated by ultraviolet-visible(UV-vis) spectroscopy, Fourier transform infrared spectroscopy(FT-IR), thermogravimetric analysis(TGA),X-ray diffraction(XRD),~1H nuclear magnetic resonance(NMR), and two-dimensional(2 D) NMR. The obtained results indicated the formation of 1∶1 inclusion complex for bakuchiol with HP-β-CD. Water solubility of bakuchiol was significantly improved by complexation with HP-β-CD as demonstrated by phase solubility studies. The encapsulation of bakuchiol was confirmed by UV-vis, FT-IR, and XRD. The thermal stability was effectively enhanced by TGA and derivative thermogravimetry(DTG) analysis. In vitro antioxidant activity showed that bakuchiol/HP-β-CD inclusion complex had a little higher antioxidant ability than free bakuchiol. Moreover, we got the possible inclusion mode for the bakuchiol/HP-β-CD inclusion complex through NMR analysis. These results suggest that the inclusion complex can be a potentially useful approach in the design of novel formulations of bakuchiol for medical applications.     

Dissolution properties of calcined gangue

To study the dissolution mechanism of gangue, dissolution characteristics of the gangue samples calcined at different temperatures in alkaline solutions and alkali metal silicate solutions with respect to Si and Al ions were analyzed by identical coupled plasma optical emission spectroscopy (ICP). The results show that the extent of dissolution of Al and Si varies with calcination temperature. It shows that the samples have a higher degree of dissolution in NaOH than in KOH medium. Si and Al appear to have synchro-dissolution behavior in alkaline solution, which means that Si and Al could dissolve from the mineral surface in certain linked forms. The result that a higher degree of dissolution exists in sodium silicate solution and a lower degree of dissolution exists in sodium-potassium silicate solution of Al is proved by the 29Si NMR spectra and the mean connectivity degree of these alkali metal silicate solutions.     

Studies on the interactions of 2,5-diphenyl 1,3,4-oxadiazole and 2,5-diphenyl 1,3-oxazole with β-cyclodextrin

Interactions of 2,5-diphenyl 1,3,4-oxadiazole (PPD) and 2,5-diphenyl 1,3-oxazole (PPO) with β-cyclodextrin (β-CD) are studied by 1H-NMR and steady-state fluorescence measurements, and the stoichiometries and the association constants are estimated. It is found that the hydrophobic interaction is the main driving force for the formation of inclusion complexes of PPD and PPO with β-CD. In the presence of aliphatic alcohols (from 1-propanol to 1-pentanol), PPD and PPO transfer from the CD cavity to the aqueous phase. Quenching experiments of PPD and PPO by iodide further prove the above conclusions. The results suggest that stereo effect is the crucial factor to the inexistence of nanotube in PPD (or PPO)-β-CD systems.     

Adsorption of Cd(II) from acidic aqueous solutions by tourmaline as a novel material

Batch experiments were conducted to investigate the behavior and mechanisms for the adsorption of Cd(Ⅱ) from aqueous solutions by tourmaline under acidic conditions. The results indicated that the adsorption of Cd(Ⅱ) significantly depend on the adsorption time, temperature, and the initial concentration of the metal ion. Furthermore, tourmaline had a very good adsorption capacity for Cd(Ⅱ) in acidic, neutral and alkaline aqueous solutions. This good adsorption capacity is attributed to the observation that tourmaline can automatically adjust the pH values of acidic (except pH 2.0 and 3.0), neutral or alkaline aqueous solutions to 6.4. Specifically, the removal capacity for Cd(Ⅱ) was higher at strongly acidic pH values (in contrast to industrial wastewater pH values) compared to that obtained for other types of adsorbents. Furthermore, the results obtained in this study showed good fits to the Langmuir and Freundlich adsorption isotherms. However, the Langmuir model fit better than the Freundlich model. The maximum uptake of Cd(Ⅱ) by tourmaline was 31.77, 33.11 and 40.16 mg/g at pH 4.0 at 15, 25 and 35°C, respectively. Therefore, tourmaline is an effective adsorbent for the removal of Cd(Ⅱ) from acidic aqueous solutions. In addition, the kinetics for the Cd(Ⅱ) adsorption by tourmaline closely followed the pseudo-second-order model. The thermodynamic parameters indicated that adsorption was feasible, spontaneous, and endothermic. Furthermore, the pH variation after adsorption, ζ-potential, metal ions desorbed and released, and FT-IR analysis indicated that the physisorption and chemisorption mechanisms of tourmaline for heavy metals. These mechanisms included water that was automatically polarized by tourmaline, the ion exchange process, and electropolar adsorption. Among the mechanisms, the automatic polarization of water caused by tourmaline is a unique adsorption mechanism for tourmaline.     

Molecular self-assembly behavior of mono[6-O-6-(4-carboxyl-phenyl)]-β-CD in solution and solid state

A novel modified cyclodextrin, mono[6-O-6-(4-carboxyl-phenyl)]-]-β-CD (1), has been synthesized by the reaction of mono[6-(p-toluenesulfonyl)]-β-CD with 4-hydroxybenzoate, and its molecular self-assembly behavior in both solution and solid state was studied by means of crystallography, NMR spectroscopy and microcalorimetry. The results indicate that the bezoic acid groups are successively penetrated intermolecularly into the adjacent β-CD cavities to form helical columnar supramolecules in the solid state. As compared with crystal, the similar self-assembly behavior of 1 in aqueous solution has also been confirmed by the ^1H ROESY spectroscopy. Thermodynamically, the formation of polymeric supramolecules by modified CD in aqueous solution is mainly driven by entropy changes.     

Hemoglobin Biocatalyst Polymerization of Aniline by UV-vis Spectraphotometry

A biocatalytic route for the synthesis of a water soluble and conducting complex of polyaniline (PAN1)/sodium dodecylsulfate (SDS) is presented. Hemoglobin is used in SDS anion surfactant . The polymerization proceeded quickly to result in a homogeneous emeraldine-colored dispersion of PANI. Absorption spectra of PANI/SDS in the aqueous dispersions at various pH values confirms that the reversibility of dedoping and redoping process of PANI/SDS and shows that the transition from emeraldine salt to emeraldine base form occurred at about pH 10.0-11.0 in this anionic micellar system. PANI/SDS in the organic solutions dedoped initially and redoped after 24h.     

Corrosion-wear behavior of nanocrystalline Fe88Si12 alloy in acid and alkaline solutions

The corrosion-wear behavior of a nanocrystalline Fe₈₈Si₁₂ alloy disc coupled with a Si₃N₄ ball was investigated in acid (pH 3) and alkaline (pH 9) aqueous solutions. The dry wear was also measured for reference. The average friction coefficient of Fe₈₈Si₁₂ alloy in the pH 9 solution was approximately 0.2, which was lower than those observed for Fe₈₈Si₁₂ alloy in the pH 3 solution and in the case of dry wear. The fluctuation of the friction coefficient of samples subjected to the pH 9 solution also showed similar characteristics. The wear rate in the pH 9 solution slightly increased with increasing applied load. The wear rate was approximately one order of magnitude less than that in the pH 3 solution and was far lower than that in the case of dry wear, especially at high applied load. The wear traces of Fe₈₈Si₁₂ alloy under different wear conditions were examined and analyzed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The results indicated that the tribo-chemical reactions that involve oxidation of the worn surface and hydrolysis of the Si₃N₄ ball in the acid solution were restricted in the pH 9 aqueous solution. Thus, water lubrication can effectively improve the wear resistance of nanocrystalline Fe₈₈Si₁₂ alloy in the pH 9 aqueous solution.     

Ab initio research on DNA base alkylation by theβ-position me-tabolite of methylethylnitrosamine

Ab initio calculation is carried out to study the different supposed mechanisms of DNA base alkylation by [β-sulphate-nitrosamines at RHF/6-31G(d) and MP2/6-31G(d) levels. Full geometric structure optimization is done for all reactants, intermediates, products and transition states. The activation energy and IRC are obtained. The results show that the anchimeric assistant effect promotes the alkylation of DNA base by β-sulphate-nitrosamines. Solvent calculation is carried out with Onsager model of SCRF method at the same level. The results indicate that the activation energy is decreased obviously in water.     

Effects of applied potential on the stress corrosion cracking behavior of 7003 aluminum alloy in acid and alkaline chloride solutions

Potentiodynamic polarization tests and slow strain rate test (SSRT) in combination with fracture morphology observations were conducted to investigate the stress corrosion cracking (SCC) behavior of 7003 aluminum alloy (AA7003) in acid and alkaline chloride solutions under various applied potentials (E_a). The results show that AA7003 is to a certain extent susceptible to SCC via anodic dissolution (AD) at open-circuit potential (OCP) and is highly susceptible to hydrogen embrittlement (HE) at high negative E_a in the solutions with pH levels of 4 and 11. The susceptibility increases with negative shift in the potential when E_a is less than -1000 mV vs. SCE. However, the susceptibility distinctly decreases because of the inhibition of AD when E_a is equal to -1000 mV vs. SCE. In addition, the SCC susceptibility of AA7003 in the acid chloride solution is higher than that in the alkaline solution at each potential. Moreover, the effect of hydrogen on SCC increases with increasing hydrogen ion concentration.     

Effect of the frequency of high-angle grain boundaries on the corrosion performance of 5wt%Cr steel in a CO<Subscript>2</Subscript> aqueous environment

The corrosion behavior of 5wt%Cr steel tempered at different temperatures was investigated by immersion testing and electrochemical testing in a CO₂ aqueous environment. When the tempering temperature exceeded 500℃, the corrosion rate increased. The corrosion layers consisted of Cr-rich compounds, which affected the corrosion behaviors of the steels immersed in the corrosive solution. The results of electrochemical experiments demonstrated that 5wt%Cr steels with different microstructures exhibited pre-passivation characteristics that decreased their corrosion rate. Analysis by electron back-scattered diffraction showed that the frequency of high-angle grain boundaries (HAGBs) and the corrosion rate were well-correlated in specimens tempered at different temperatures. The corrosion rate increased with increasing HAGB frequency.     

Effect of the frequency of high-angle grain boundaries on the corrosion performance of 5wt%Cr steel in a CO_2 aqueous environment

The corrosion behavior of 5 wt%Cr steel tempered at different temperatures was investigated by immersion testing and electrochemical testing in a CO_2 aqueous environment. When the tempering temperature exceeded 500℃, the corrosion rate increased. The corrosion layers consisted of Cr-rich compounds, which affected the corrosion behaviors of the steels immersed in the corrosive solution. The results of electrochemical experiments demonstrated that 5 wt%Cr steels with different microstructures exhibited pre-passivation characteristics that decreased their corrosion rate. Analysis by electron back-scattered diffraction showed that the frequency of high-angle grain boundaries(HAGBs) and the corrosion rate were well-correlated in specimens tempered at different temperatures. The corrosion rate increased with increasing HAGB frequency.     

Molecular recognition study on a supramolecular system (Ⅷ) --The fluoroscopic study on inclusion complexation of adamantanol with cyclodextrin derivatives

The fluorescence spectral titrations have been performed in phosphate buffer solution (pH 7 2) at room temperature to give the stability constants for inclusion complexation of a series of chemically modified β cyclodextrins bearing aromatic groups with adamantanol. The molecular recognition mechanism is discussed from the viewpoint of the structural factors, electron effect of the substitutent groups and the size and chain length of the fluorophore. The results indicate that the complex stability of the cyclodextrin derivatives bearing a positively charged pyridinio moiety can be enhanced by the electrostatic interaction between the host cyclodextrins and the adamantanol guest and the microenvironment change plays a crucial role in the inclusion complexation.     

Study on TEMPO-Mediated Selective Oxidation of Alkaline Natural Cellulose Pulp and Properties of Its Products

It has been reported that natural cellulose(celluloseⅠ) can not be oxidized by TEMPO - NaOCl -NaBr system, one of TEMPO-mediated selective oxidantsystems, but regenerated cellulose(cellulose Ⅰ)can becompletely selectively oxidized. In the present work,natural cellulose pulp was treated with NaOH solution,which concentration is lower than 20 wt%. The alkalinecelluloses obtained were oxidized by TEMPO - NaOCl -NaBr system and the factors which influence the selectiveoxidation reaction rate have been investigated. Thestructure of the oxidized products has been characterizedby Fourier transform-infrared(FTIR), nuclear magenaticresonace(NMR) and wide angle X-ray diffraction(WAXD) methods, and their adsorption properties forCu2 and Cd2 in aqueous solutions have beenpreliminarily examined. The results show that after thealkaline treatment, the primary hydroxyl at C6 position ofnatural cellulose can be selectively oxidized to carboxylgroup in the reaction medium at pH 10.8, the oxidationrate becomes greater with the NaOH concentration andalkaline treatment time increasing. The alkaline treatmenthas a great effect on the crystal structure of naturalcellulose, but the crystal structure of alkaline cellulosekeeps almost unchanged after oxidation. The adsorptioncapacity is enhanced by introducing carboxyl groups intothe cellulose macromolecular chains.     

The synthesis and properties study of 6,13-diphenylpentacene

6,13-diphenylpentacene（DPP） was synthesized by 6,13-pentacenequinone and the Grignard reagent with the SnCl2/HCl as the reducing agent. It was detected by ^1H NMR, infrared spectra, X-ray diffraction （XRD）, UV-visible spectra and fluorescence spectra. Substitution with phenyl at the C-6 and C-13 positions of pentacene leads to phenomenal enhancement in solubility and a little enhancement in photooxidative stability. XRD results showed that the pattern of 6,13-diphenylpentacene was different from the patterns of pentacene and 6,13-pentacenequinone. UV-Visible spectra showed that the λmax of DPP in HCCl3 was 600 nm. The fluorescence spectra showed that DPP emitted purple （430 nm） and red （612 nm） when excited by UV, while only emitted red when excited by visible light. But it is still susceptible to photooxidation. The photooxidation product of DPP was also studied.     

Swelling Behaviors of Polyaniline-Poly（Acrylic Acid） Hydrogels

Using poly（acrylic acid） （PAA） aqueous solution, NaOH aqueous solution, aniline （An） and ammonium persulfate （APS）, PAn-PAA hydrogels with a semi-interpenetrating structure connected by physical interlocks, chemical ion bonds and hydrogen bonds were prepared. The swelling properties of the hydrogels in solutions of different pH values （adjusted by adding NaOH or HCI） were studied. All the hydrogels prepared have similar swelling curves （the curves of equilibrium swelling ratio vs. pH value） and reach their maximum swelling at pH of 8 - 10. The maximum swelling ratio of the hydrogels is dependent on composition, including molecular weight of PAA, polymer content of the hydrogel, and molar ratios of AA to An, APS to An, and NaOH to AA, And the compositional dependence of the swelling capacity of PAn-PAA hydrogels was also studied.     

Dissolution behavior and dissolution mechanism of palygorskite in HCl solution

The 1 mol/L, 3 mol/L and 5 mol/L HCl solutions were employed to leach two palygorskites with different trioctahedral contents in their crystal structure for different period of time. The results of the dissolution experiments show that the dissolution process could be divided into three steps, and that this dissolution behavior can be attributed to its higher Mg2+ content, and is restricted by the extraction behavior of Si4+. The preferential extraction for Mg2+ promotes the extraction behavior of Si4+ from Si-O framework. Because the Si4+ in the form of amorphous SiO2 is adsorbed onto the surface of palygorskite fibre, the reaction between palygorskite and acid is obstructed. With the elapsing of time, or the increasing of the acid concentration, the amorphous SiO2 flocculates, and then the channels of chemical reaction are reopened. The ratio value of Mg2+/(Fe3++Al3+) in leaching solution tends to a fixed value, showing that the acid attacks not only the surface but also the structural channels. There are no obvious three steps observed during the acid attack on the palygorskite with a lower trioctahedral content. The differential behavior for two palygorskites is discussed.     

Slime coating of kaolinite on chalcopyrite in saline water flotation

In saline water flotation, the salinity can cause a distinguishable slime coating of clay minerals on chalcopyrite particles through its effect on their electrical double layers in aqueous solutions. In this work, kaolinite was used as a representative clay mineral for studying slime coating during chalcopyrite flotation. The flotation of chalcopyrite in the presence and absence of kaolinite in tap water, seawater, and gypsum-saturated water and the stability of chalcopyrite and kaolinite particles in slurries are presented. Zeta-potential distributions and scanning electron microscopy images were used to characterize and explain the different slime coating degrees and the different flotation performances. Kaolinite particles induced slime coating on chalcopyrite surfaces and reduced chalcopyrite floatability to the greatest extent when the pH value was in the alkaline range. At 0.24wt% of kaolinite, the chalcopyrite floatability was depressed by more than 10% at alkaline pH levels in tap water. Salinity in seawater and gypsum-saturated water compressed the electrical double layers and resulted in extensive slime coating.     

~1H NMR Investigation of Supramolecular Complex between β-Cyclodextrin and Cholesterol

A supramolecular complex between β-cyclodextrin and cholesterol was synthesized and characterized via proton 1H NMR spectroscopy. In the supramolecular complex,the stoichiometric proportion of β-cyclodextrin to cholesterol is 1:2. The possible conformation of the supramolecular complex was depicted according to the chemical shift variance of proton 1H NMR of the host and guest molecules inside the inclusion complex. Removal efficiency of cholesterol complexed by β-cyclodextrin in our work is increased to a remarkable extent. This result can be applied in the field of drug development to reduce cholesterol in blood and other human organs.