SnO2:xEu3+(x=0, 1%, 3%, 5%, molar fraction) fibers were synthesized by electrospinning technology. The size of the as-prepared fibers is relatively uniform and the average diameter is about 200 nm with a large draw ratio. The as-prepared Eu3+ doped SnO2 nanofibers have a rutile structure and consist of crystallite grains with an average size of about 10 nm. A slight red shift of the A1g and B2g vibration modes and an additional peak at 288 nm were observed in the Raman spectra of the nanofibers. The energies of bandgaps of the SnO2 nanofiber with Eu doping of 1% and 3% are 2.64 eV, and the energy of bandgap is 2.94 eV with Eu doping of 5%(molar fraction). There is only orange emission(5D0→7F1 magnetic dipole transition) for Eu doped SnO2 nanofibers, and no red emission could be observed. The orange emission upon indirect excitation splits into three peaks and the peak intensity at the excitation wavelength of 275 nm is higher than that at the excitation wavelength of 488 nm.
A novel 3D ytterbium supramolecular compound, [Yb(HBDDC)(H2O)4]·2H2O(1), was synthesized via 5,5'-(buta-diyne-1,4-diyl)diisophthalic acid ligand(H4BDDC) under solvothermal conditions. Single-crystal X-ray diffraction analysis reveals that compound 1crystallizes in triclinic system, Pī space group with a=0.71372(14) nm, b=1.0566(2) nm, c=1.7969(4) nm, α=101.01(3)°, β=98.15(3)°, γ=99.17(3)° and V=1.2922(4) nm3. Compound 1 exhibits a special infinite 1D chain, which stacks parallel each other in an ABAB sequence, leading to the formation of a 3D supramolecular structure owing to the strong π-π interactions between adjacent phenyl ring groups. Moreover, compound 1 manifests excellent luminescent property.
Three novel compounds, [Co(en)3]2[Zr2(C2O4)7]·2H2O(HNU-2, en=ethylenediamine), [Co(NH3)6]·[Ce(C2O4)3(H2O)]·H2O(HNU-3) and [Co(dien)2][Gd(C2O4)3]·0.75H2O(HNU-4, dien=dethylenetriamine) were hydrothermal synthesized based on the templates of [Co(en)3]Cl3, [Co(NH3)6]Cl3 and [Co(dien)2]Cl3, respectively. The Zr4+, Ce3+ and Gd3+ cations are all coordinated by four oxalates to form [M(C2O4)4(H2O)n]m-(M=Zr, Ce or Gd; n=0 or 1; m=4 or 5), which are similar to [In(C2O4)4]5- in NKB-1, and can be regarded as 4-connected building units. The [M(C2O4)4(H2O)n]m- units are connected via sharing the bis-bidentate bridging oxalate ligands to form binuclears in HNU-2 and 1D “zigzag” chains in HNU-3 and HNU-4. It is suggested that these compounds could be used as molecular building units to design 3D open frameworks with zeolite topologies.
A new catalytic-oxidation method was adopted to remove the templates from SBA-15 and MCM-41 mesoporous materials via Fenton-like techniques under microwave irradiation. The mesoporous silica materials were treated with different Fenton agents based on the template's property and textural property. The samples were characterized by powder X-ray diffraction(XRD) measurement, N2 adsorption-desorption isotherms, infrared spectro- scopy, 29Si MAS NMR and thermo gravimetric analysis(TGA). The results reveal that this is an efficient and facile approach to the thorough template-removal from mesoporous silica materials, as well as to offering products with more stable structures, higher BET surface areas, larger pore volumes and larger quantity of silanol groups.
A rapid and sensitive liquid chromatography-tandem mass spectrometry(LC-MS/MS) method for the determination of cefotetan in human plasma was developed and validated. After the protein precipitation of sample with acetonitrile, the analyte and internal standard(IS), tramadol, were separated on a Zorbax XDB C8 column using acetonitrile/1%(volume fraction) formic acid(volume ratio 35:65, pH=2.5) as mobile phase at a flow rate of 1.0 mL/min with a 1:1 split. The detection was performed by electrospray ionization with positive ion mode, followed by multiple reaction monitoring of the transitions for cefotetan at m/z 576.3→460.2(quantifier) and m/z 576.3→432.2(qualifier) and for IS at m/z 264.1→58.1. Cefotetan and IS were eluted at 1.86 and 1.87 min, respectively. The assay was linear over the concentration range of 0.1―100 μg/mL for 20 μL of human plasma only with intra- and inter-day precisions(expressed as the relative standard deviation) of less than 6.62% and accuracies(as relative error) of ±1.31%. The method was applied to the pharmacokinetic study of a 1-h intravenous infusion of 1.0 g of cefotetan disodium for human volunteers(n=6).
A novel type of carboxylated multiwalled carbon nanotube modified electrode(c-MWCNTs/GCE) was constructed and the electrochemical properties of phenacetin(PHE) at it were studied. In a buffer solution of 0.1 mol/L HAc-NaAc(pH=5.3), PHE exhibited a couple of quasi-reversible redox peaks and an anodic peak in the potential range of 0.2―1.2 V at c-MWCNTs/GCE. The peak current was proportional to the concentration of PHE in the range of 4.0×10-6―1.0×10-4 mol/L with a detection limit of 1.0×10-6 mol/L(S/N=3). The c-MWCNTs/GCE showed excellent repeatability and stability and the electrochemical reaction mechanism of PHE was proposed. This method was used to determine the content of PHE in medical tablets and the recovery was determined to be 96.5%―104.2% by means of a standard addition method.
Two sulphur-containing 4-aminonaphthalimide derivatives were investigated as Hg2+ fluorescent chemosensors. In CH3CN, both sensors present a remarkable fluorescence enhancement to Cu2+ and Fe3+, but a selective fluorescence quenching to Hg2+ among the other metal ions. A cation-π interaction between Hg2+ and the naphthalimide moiety was proposed and confirmed by the density functional theory(DFT).
(S)-3-Hydroxy-3-phenylpropanoic acid is a potential progenitor of optically pure tomoxetine hydrochloride and fluoxetine hydrochloride which are currently available antidepressant drugs. We report here the chemical synthesis of racemic substrate (R,S)-ethyl 3-hydroxy-3-phenylpropanoate and enzymatic preparation of S-isomer of the substrate by employing Porcine pancreas lipase(PPL) as a biocatalyst. Optimum enzyme-catalyzed reaction conditions, such as the effects of the temperature, pH and solvents on conversion degree and enantiomeric excess, were studied. An optimal temperature of 35 ℃ and pH=7.5 are the best for the resolution of (R,S)-ethyl 3-hydroxy-3- pheylpropanoate by PPL when 0.1 mol/L phosphate buffer solution acts as a medium. This work provides a practically chemo-enzymatic preparation of chiral β-hydroxy acid by PPL.
A series of calixpyrrole meso-substituted Schiff bases was synthesized with 5α,10α-di(4-hydroxylphenyl)calixpyrrole or 5α,15β-di(4-hydroxylphenyl)calixpyrrole as starting materials. The synthetic routes included alkylation with methyl α-chlroroaceate, ammonolysis with alkylene diamine, and condensation with salicylladehyde or 2-hydroxynaphthaldehyde. The crystal structures of the new calixpyrroles and their Schiff bases were determined by X-ray diffraction. The coordination properties of the representative calixpyrrole Schiff bases to transition metal ions were also investigated by UV-Vis spectra.
Two series of 7-O-modified chrysin derivatives were prepared from 7-O-carboxymethyl chrysin(2a), 7-O-carboxypropylchrysin(2b) and short-chain alcohols by using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride(EDCI), N-hydroxybenzotriazole(HOBt) and 4-dimethylamiopryidine(DMAP) as coupling reagents. Taking cisplatin as a reference substance, their anti-proliferative activities in vitro against human gastric carcinoma MGC-803 cells were evaluated by the standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) method. The results show that among the compounds tested, hepty 4-(5-hydroxy-4-oxo-2-phenyl-4H-chromen-7-yloxy) acetate(3f) displayed the most potent growth-inhibitory effect on MGC-803 cells with half maximal inhibitory concentration(IC50) value of 3.23 μmol/L. The preliminary mechanism of inhibitory effect of compound 3f was also detected by flow cytometry(FCM), and the compound exerted anti- cancer activity via inducing the apoptosis of MGC-803 cells in a dose dependent manner, which suggested that compound 3f would be a potential anti-cancer agent.
To make further studies on the difference of cis-nitenpyram analogues, a series of cis-nitenpyram compounds containing a flexible amido segment anchored on tetrahydropyrimidine ring was designed and synthesized. Preliminary bioassays indicate that all the analogues exhibit a mortality of 100% at 100 mg/L, and the analogue 4d shows the best activity against Nilaparvata lugens and Myzus persicae, with a mortality of 100% at 4 mg/L (LC50=0.172 mg/L). The structure activity relationship studies show that insecticidal activities of the analogues are affected by the kinds and size of substituent R. In addition, the molecular docking simulations reveal that compouds 4 with a flexible amido segment on tetrahydropyrimidine ring show their different binding affinities for the nicotinic acetylcholine receptor(nAChR) of insect and compoud 4d shows stronger hydrogen-bonding with nAChR, which may provide the structure-activity relationship observed in vitro.
A series of derivatives of tetrandrine and fangchinoline was designed and synthesized to find more active anti-cancer compounds. Their anti-cancer activities were tested against human hepatocellular carcinoma BEL-7402 and PLC/PRF/5 cells, human lung adenocarcinoma A549 cells as well as human leukaemia K562 cells, and the structure-activity relationship(SAR) was also studied. All the compounds except B1 exhibited superior inhibitory activities against PLC/PRF/5 cells with half maximal inhibitory concentration(IC50) values of less than 15 μmol/L, and compounds A2, A4, B2 and B4 showed IC50 values of less than 9 μmol/L. Compounds A2, A6, B2 and B4 showed potent anti-cancer activities against all the tested cells with IC50 values of less than 10 μmol/L. The results show that terandrine and fangchinoline derivatives are potential suppressors to human cancer.
Sixteen resveratrol analogs(stilbene derivatives) including resveratrol were synthesized, in which hydroxystilbenes, naturally occurring polyphenols, showed protective effects against reactive oxygen and nitrogen species(ROS/RNS) and hexahydroxystilbene(16) displayed the strongest activities against NO and 1,1-diphenyl- 2-picrylhydrazyl(DPPH) with IC50 values of 7.8 and 5.7 μmol/L, respectively.
In this paper, we constructed a novel bifunctional superoxide dismutase(SOD)/glutathione peroxi- dase(GPx) mimic, a selenium-, copper-containing 35-mer peptide conjugate(Se-Cu-35P) in which a three-amino acid linker(Gly-Asn-Gly) connects the C-terminus of 17-mer polypeptide SOD mimic with the N-terminus of 15-mer polypeptide GPx mimic. The SOD and GPx activities of Se-Cu-35P are two orders of magnitude lower than those of natural SOD and GPx, respectively. It provides a GPx activity 56-fold higher than Ebselen(a well-known GPx mimic). The glutathione(GSH) binding constant is 5.6×102 L·mol-1. Se-Cu-35P synergistically resists against the inactivation by H2O2 and protects the mitochondria from oxidative damage in a dose dependent manner. These results highlight the challenge of generating an efficient SOD/GPx synergism mimic. It could facilitate the studies of the cooperation of GPx and SOD and could be a potential therapeutic agent for the treatment of ROS-mediated diseases.
In this paper, cinobufagin and resibufogenin were found to inhibit enterovirus 71(EV71) infection in vitro in cell viability and plaque reduction assays. The 50% inhibitory concentrations(IC50) of cinobufagin and resibufogenin were (10.94±2.36) and (218±31) nmol/L, respectively, the 50% cytotoxic concentrations(CC50) of them were (1277±223) and (1385±254) nmol/L, respectively, and the anti-EV71 selectivity index(SI50) of cinobufagin was 116.7, which are promisingly developed into drug. Using a VP1 detection assay and a constructed reporter luciferase, we found that cinobufagin and resibufogenin disrupted the synthesis of EV71 protein. However, neither of them inhibited EV71 RNA replication. Our study suggests that cinobufagin and resibufogenin are the promising candidates that should be further investigated for the treatment of EV71 caused disease.
In this work, we synthesized the polypyrrole(PPy) modified gold nanoparticles and demonstrated their negligible cytotoxicity in vitro. These nanoparticles have also been demonstrated to efficiently ablate different kinds of tumor cells in vitro under the irradiation of the near-infrared laser. When the PPy modified gold nanoparticles were conjugated with the tumor-targeted molecule of 15P(sequence: SHSWHWLPNLRHYAS), these conjugates displayed hyperthermia effects on the human ovarian cancer cell line SK-OV-3 cells in vitro under the irradiation of near-infrared laser, showing great tumor-targeted treatment efficiency. To determine the potential hyperthermia effect of PPy modified gold nanoparticles or 15P-conjugate on tumor cells in vivo, the SK-OV-3 cells were used to induce the subcutaneous tumor-bearing nude mice. The significant inhibition effects of near-infrared laser mediated PPy modified gold nanoparticles or 15P-conjugate on the tumor growth were observed. These composite results suggest that the 15P-conjugated PPy modified gold nanoparticles exhibit great biocompatibility, particularly tumor-targeted effect and the effective photothermal ablation of tumor cells, which warrants the potential therapeutic value of this conjugate for further application to the in vivo localized tumor therapy.
This work focuses on the H2 sensing performance of the sensor with buried Au sensing electrode and spinel-type oxide CoCrMnO4 insensitive reference electrode within sodium super ionic conductor(NASICON) film. The sensor showed the highest response to H2 gas on the insensitive material sintering at 800 ℃. Compared with those of the traditional structure device, the sensitivity and selectivity of the sensor using buried sensing electrode were greatly improved, giving a response of -177 mV in 9×10-5 g/L H2, which was about 3.5 times higher than that of sensors with traditional structure. Moreover, the ΔV value of the sensing device exhibited linear relationship to the logarithm of H2 concentration and the sensitivity(slope) was -135 mV/decade. A sensing mechanism related to the mixed potential was proposed for the present sensor.
Surface modification of halloysite nanotube(HNT) with in situ grown Fe3O4 nanoparticles and carbonaceous layers introduced by a hydrothermal carbonization process of glucose has been achieved. Structure and morphology investigations demonstrate that iron oxide nanoparticles are uniformly anchored on the halloysite and prevent the aggregations of halloysite and carbon, forming a protective layer that stabilizes and improves the property of HNT/Fe3O4/C nanocomposite. Magnetism characterization proves the superparamagnetic behavior of HNT/Fe3O4/C hybrid at room temperature, which makes it easily separated from dye solution under an external magnetic field. Exploration of adsorption ability demonstrates that the maximum adsorption capacity of the as-prepared HNT/Fe3O4/C nanocomposite for methylene blue(MB) is about twice and 1.5 times those of HNT/Fe3O4 and HNT according to Langmuir equation, respectively. The adsorption behavior investigations indicate that HNT/Fe3O4/C hybrid has a heterogeneous structure and shows a non-ideal monolayer adsorption that fits the Redlich-Peterson isotherm, and the adsorption process follows a pseudo-second-order kinetic model. Therefore, the as-prepared HNT/Fe3O4/C hybrid is a fast, separatable and superparamagnetic adsorbent with a good adsorption ability, demonstrating great potential in the application of water treatment.
The solubilities, densities and refractive indices for the four ternary systems ethylene glycol/glycerin+ RbNO3/CsNO3+H2O were measured with mass fractions of ethylene glycol or glycerin in a range of 0 to 1.0 at 288.15 and 298.15 K. In all the cases, the presence of either ethylene glycol or glycerin significantly reduces the solubilities of the rubidium nitrate and cesium nitrate in aqueous solution, but the refractive indices increase with the increase of mass fraction of either ethylene glycol or glycerin. The density, refractive index and solubility of the saturated ternary systems were correlated with each other via polynomial equations. In addition, the refractive indices and densities of unsaturated solutions were also determined for the four ternary systems with different salt concentrations, which were correlated with the salt concentration and proportion of ethylene glycol or glycerin in the solution.
PbSe films with different nanostructures, such as nanoparticles, nanohollows and hierarchical structures, can be synthesized by adjusting the current density and the reaction temperature via a convenient and efficient electrochemical route in the absence of hard template and surfactant. The calculated band gaps of the prepared PbSe nanoparticles and nanohollows were about 0.32 and 0.43 eV, respectively. This suggests that quantum size effect in nanohollows greatly influences their band gap. This preparation method possesses remarkable advantages, such as low cost, high efficiency and easy preparation, which are very suitable for preparing nanomaterials.
The catalytic activity of VO(acac)2 for the cyclohexane(Cy) oxidation was studied. The effects of various parameters, such as the amounts of H2O2, HNO3, H2O and Cy were investigated. The highest total turnover number(TON) is 234, which can be increased to 353, 342 and 403, respectively with the adding of o-phthalic, m-phthalic or p-phthalic acid. A reaction mechanism was also supposed primarily.
The optimal geometry, IR spectrum and vibration assignment of 4,4'-dibromodiphenyl ether(BDE-15) in gas phase were calculated via the density functional theory(DFT) at the level of B3LYP/6-31+G(d). Based on the vibration assignment, the calculation of vibration frequencies and intensities of 5 main vibration types of BDE-15 in 25 kinds of solvents was carried out by means of a self-consistent reaction field(SCRF) theoretical model at the level of B3LYP/6-31+G(d) to analyze the solvent effect on the vibration of IR spectrum of BDE-15. To study the solvent effect further, C―O asymmetric stretching vibration fluctuating, which is relatively acute in both vibration frequency and intensity, was selected as the characteristic vibration to establish different linear solvation energy relation(LSER) models for solvent categoring. Solvent parameters(α, β, π*), acceptable number(AN) and quantitative structure- activity relationship(QSAR) models were established via chemical quantum parameters of solvent moleculer, which were first been introduced to investigate different solvent-solute interaction mechanisms in alcoholic and non-alcoholic solvents on molecular level. At last, a single solvent molecule was embedded in the framework of polarizable continuum model(PCM) to validate the effect of hydrogen bonding on solvent-solute interaction in alcohol solvents. The obtained results show that 5 main vibration types of BDE-15 in different solvents have small variation range in frequency and intensity and all the vibration frequencies in solvents are lower than those in gas phase, decreasing along with the increasing of the dielectric constant(ε) of solvents exponentially. In contrast, all the vibration intensities in solvents are greater than those in gas phase and present positive exponential trend. Twenty-five solvents were divided into two categories(non-alcoholic solvents and alcoholic solvents) by LSER. The C―O asymmetric stretching vibration was mainly regulated by non-specific interaction(dipole-dipole and dipole-induced dipole inter- action) and the combination of non-specific interaction and electronic effect in non-alcoholic solvents and alcoholic solvents, respectively. R2 values of the two QSAR models established for different categories are 0.940 and 0.997, both showing good fitness and the decisive parameters for the two models are μ, αzz and αyy, EHOMO separately, which reflect that the interaction mechanism is coincide with the conclusion obtained by LSER model. The present of hydrogen bonding in alcoholic solvents improves the differentiation degree of vibration frequency of the two models with the variance increasing from 0.281 to 0.513 and the intensity from 5.263 to 10.382, which is conducive to the identification of polybrominated diphenyl ether(PBDE) homologues, indicating this research would provide theoretical gist for linking the experimental IR spectrum data with the identification of PBDE homologues.
The W-doped Fe/TiO2 catalyst prepared by an impregnation method exhibited a good NH3-selective catalytic reduction(SCR) activity and N2 selectivity with broad operation temperature window. The interaction between Fe and W could increase the amount of surface chemisorbed oxygen, and thus enhances the low temperature SCR activity by facilitating the fast SCR of 2NH3+NO+NO2→2N2+3H2O. The NH3-SCR reaction mechanism over the W-Fe/TiO2 was fully investigated via in situ diffuse reflectance infrared Fourier transform spectroscopy(in situ DRIFTS). In the low temperature range(<250 ℃), the reactive surface species were mainly coordinated NH3, ionic NH+4 and adsorbed NO2 species, and the SCR mainly followed the Langmuir-Hinshelwood mechanism, during which the adsorbed NO2 species became the important active sites. In the high temperature range(>250 ℃), the reactive surface species were mainly NH2, and the SCR mainly followed the Eley-Rideal mechanism, during which the formation of NH2NO intermediate species after H-abstraction of NH3 was the rate-determining step.
Chemoreceptor TlpB(Tlp=transducer-like protein), which has been demonstrated to respond to pH sensing function, is crucial for the survival of Helicobacter pylori(H. pylori) in host stomach. Urea was proposed to be essential for TlpB's pH sensing function via binding with the Per-ARNT-Sim(PAS) domain of TlpB. Additionally, K166R mutation of the TlpB protein has also been proven to have a similar effect on TlpB pH sensing as urea binding. Although X-ray crystallographic studies have been carried out for urea-bound TlpB, the molecular mechanism for the stabilization of TlpB induced by urea binding and K166R mutation remains to be elucidated. In this study, molecular dynamics simulations combined with principal component analysis(PCA) for the simulation results were used to gain an insight into the molecular mechanism of the stabilization of urea on TlpB protein. The formed H-bonds and salt-bridges surrounding Asp114, which were induced by both urea binding and K166R mutation of TlpB, were important to the stabilization of TlpB by urea. The similarity between the urea binding and K166R mutation as well as their differences in effect has been explicitly demonstrated with computer simulations at atomic-level. The findings may pave the way for the further researches of TlpB.
A novel porous aromatic framework, PAF-52, was obtained via the polymerization of tetrahedral monomer tetrakis(4-cyanodiphenyl) methane(TCDPM) with the aid of a facile ionothermal method. PAF-52 has a surface area of 1159 m2/g(BET), and shows a considerable high separation ability of CO2 in N2 or CH4 respectively at room temperature, using gas-chromatography experiments as evidence.
The effect of compressive residual stress on the reactivity of carbon steel in a neutral chloride solution was investigated by means of potentiodynamic polarization and local electrochemical measurement with scanning electrochemical microscope(SECM). Meanwhile, X-ray diffraction, as a nondestructive technique, was employed to determine the levels of residual stress in near-surface layers of carbon steel specimen. The results show that the residual stress existed in the specimen fell into the category of compressive residual stress which was inversely proportional to the corrosion sensitivity of carbon steel specimen. By using I-/I3- couple as a redox mediator in the current feedback mode of SECM measurements, the Faradaic current on Pt tip, which was relevant to the rate of the I3- ion reduction, fell with the increase of compressive residual stress. The correlation between compressive residual stress and heterogeneous electron transfer rate has been proposed based on the inference of the localized electrochemical reactions occurred on the specimen surface.
Thermal degradation and degradation kinetics of methylphenylphosphinic acid(MPPA) and diphenylphosphinic acid(DPPA) were investigated via thermogravimetric analysis(TGA) technique under non-isothermal conditions. The activation energies of the decomposition process for the two compounds were calculated through the Friedman and Kissinger-Akahira-Sunose(KAS) methods. The thermal decomposition mechanism was investigated by the Criado method based on a set of TGA data obtained at different heating rates. It was shown that the activation energies calculated from the decomposition reaction by different methods were consistent with each other. The results show that the probable model for the degradation of MPPA and DPPA agreed with the two-dimensional(D2) and three-dimensional(D4) diffusion models, respectively. Moreover, the thermodynamic functions(ΔH≠, ΔS≠, ΔG≠) of the two decomposition reactions were also calculated.
Using bowl shaped carbon intermediates to construct dihedral fullerenes is an advisable method. Assu- ming that cap shaped C21 extends the size through building pentagons and hexagons at the U and V clefts of the brims, a series of homologous carbon intermediates was generated, in which most of the members have been unknown up to now. The joins between these homologous intermediates gave the C3 dihedral series under the restriction of C3 symmetrical axis. The investigations point out that the stabilities of these fullerenes not only relate to the shapes of cages and the co-planarities of polygons, but also associate with the equalizations of bond lengths and the pentagonal distributions. The stabilities reveal that the pentagonal distribution in cages is not negligible to the π delocalization, besides the co-planarities of hexagons and pentagons. Analyzing the possible Stone-Wales(SW) rearrangements in those fullerenes with dehydrogenated pyracyclene units(DPUs) can help us to find out the highly stable isomers. Based on the geometrical optimizations, the calculations provided the theoretical chemical shifts of unknown fullerenes and the data reconfirmed the existence of members C78 and C84. The symmetry adaptation analyses for the frontier orbitals support the formative mechanism of consecutive pentagonal and hexagonal fusions, but the simulated routes are more complicated than the pentagon road(PR) mechanism, which include not only C2 but also C3 additive reactions.
Flowerlike supramolecular architectures were fabricated from fulleropyrrolidines bearing a small para-, meta-, or ortho-nitrophenyl group. The self-assembled architectures were characterized by scanning electron microscopy(SEM) and X-ray diffraction(XRD). It was found that these flowerlike architectures were assembled from nanoplates that formed from fundamental subunit of interdigitated lamellar bilayer structure.
Imidazole-containing polyimide/silica(PI/SiO2) hybrid films were prepared from 3,3',4,4'-biphenyltetra- carboxylic dianhydride(BPDA) and 2,2'-di(p-aminophenyl)-5,5'-bibenzimidazole in N,N-dimethylacetamide(DMAc) by sol-gel method and thermal imidization. The hybrid film with high silica mass fraction up to 40% was transparent. Scanning electron microscope(SEM) and transmission electron microscope(TEM) results of the film indicate a homogeneous dispersion of silica nanoparticles in the polyimide matrix. One hybrid film PI/SiO2 with 15% SiO2 exhibits better mechanical properties with a tensile strength of 222 MPa, an elongation at break of 12%, and a tensile modulus of 5.66 GPa. The reinforced mechanism on mechanical properties was also studied.
The asymmetric alkylation reactions induced by non-cross-linked polystyrene supported cyclosulfamide chiral auxiliary occurred in moderate to good yields with a very high stereoselectivity(e.e.>99%). Compared to non-supported cyclosulfamide chiral auxiliary, this chiral auxiliary can be recovered by simple precipitation and filtration, and could be reused at least four cycles without appreciable reduction in the yield or stereoselectivity.
The insoluble β-cyclodextrin/glutaraldehyde crosslinked polyvinylpyrrolidone nanofibrous membranes were prepared by electrospinning technique. The membranes were extensively characterized by various techniques including attenuated total reflectance Fourier transform infrared spectroscopy(ATR-FTIR), X-ray diffraction(XRD), scanning electron microscopy(SEM) and UV-visible absorption to correlate membrane characteristics with their performance. The adsorption ability of the nanofibrous membranes was tested by performing extraction of Methyl orange(MO) dye in water. It was observed that β-cyclodextrin incorporated in polyvinylpyrrolidone provided the characteristics of high adsorption capacity of polyvinylpyrrolidone. Results of sorption experiments show that the nanofibrous membranes exhibited an adsorption rate of more than 95% for MO and the MO absorbent was 39.82 mg to per gram of β-cyclodextrin glutaraldehyde(β-CDXFM) crosslinked PVP under the optimized experimental conditions.
In order to tune the surface properties of hydroxyapatite(HA) nanoparticles and prevent them from aggregation, an efficient method was proposed to graft chitosan(CS) molecules on the surface of HA via “click” reaction. Thermal gravimetric analysis(TGA) shows that CS was successfully grafted on the surface of HA nanoparticles and the grafting amount was about 8.9 g of CS on per hundred grams of HA. The grafted chitosan chains can prevent HA nanoparticles from aggregation and greatly enhance the colloidal stability of HA in water. The 3-(4,5-dimethylthiazoyl-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay demonstrats that the cytotoxicity of CS modified HA(HA-CS) is negligible and thus HA-CS may find potential application in biomedical fields.
The separation of aromatic hydrocarbons from aromatic/aliphatic mixtures was investigated with cross- linked polystyrene(CPS) beads modified with sulfonyl groups. Three sulfonating agents, i.e. benzenesulfonyl chloride(BsCl), 4-toluene sulfonyl chloride(TsCl) and methanesulfonyl chloride(MsCl) were used to prepare sulfonyl CPS beads by Friedel-Crafts reaction. The CPS beads modified with BsCl exhibited higher sulfonation rate than those modified with MsCl and TsCl and obtained optimum selectivity in the experiments of toluene/n-heptane separation. Further separation tests with various other aromatic/aliphatic mixtures were carried out at an initial aromatic concentration of 13%(mass fraction) with the results showing that the modified beads have preferential selectivity for aromatic hydrocarbons in all aromatic/aliphatic mixtures, and especially a separation factor of 8.21 and a swelling ratio of 30% for toluene/cyclohexane system. The thermal stability and regeneration test indicate that the used polystyrene beads can be recovered through heat-drying and reused effectively.
The biodegradable superhydrophobic cellulose sheets were fabricated by simple dissolution, controllable crystallization, coagulation, and Teflon dip-coat. The surface morphology of the superhydrophobic regenerated cellulose sheets is similar to that of the natural lotus leaves consisting of hierarchical micro/nano structures. The prepared cellulose sheets exhibit a remarkable superhydrophobicity and satisfactory long-term chemical stability.