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961.
U. Gianfranco Spizzirri Francesca Iemma Francesco Puoci Feng Xue Wei Gao Giuseppe Cirillo Manuela Curcio Ortensia I. Parisi Nevio Picci 《先进技术聚合物》2011,22(12):1705-1712
Novel stimuli‐responsive hydrophilic microspheres were prepared by free radical polymerization of hydroxyethyl methacrylate (HEMA) and methacrylic acid (MA), as hydrophilic monomers, and N‐isopropylacrylamide (NIPAAm) and N,N′‐ethylenebisacrylamide (EBA), as thermo‐sensitive monomer and crosslinker, respectively. Hydrophilic comonomers were introduced in the macromolecular network to synthesize materials with tunable thermal behavior. In addition, by introducing in the polymerization feed both a hydrophilic and a pH‐sensitive monomer, such as MA, dual stimuli‐responsive (pH and temperature) hydrogels were synthesized. The incorporation of monomers in the network was confirmed by infrared spectroscopy, while the network density and the shape of hydrogels was found to strictly depend on the concentration of monomers in the polymerization feed. Thermal analyses showed negative thermo‐responsive behavior with pronounced water affinity of microspheres at a temperature lower than lower critical solution temperature (LCST). In our experiment, the LCST values of the hydrogels were in the range 34.6–37.5°C, close to the body temperature, and the amount of hydrophilic moieties in the polymeric network allows to collect shrinking/swelling transition temperatures higher than the LCST of NIPAAm homopolymers. In order to test the preformed materials as drug carriers, diclofenac diethylammonium salt (DDA) was chosen and drug entrapment percent was determined. Drug release profiles, in media at different temperature and pH, depend on hydrogels crosslinking degree and drug–bead interactions. By using semi‐empirical equations, the release mechanism was extensively studied and the diffusional contribute was evaluated. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
962.
The polyanion [AgAs(2)Mo(15)O(54)](11-) has an unusual cage-like structure composed of [AsMo(6)O(27)](15-) and [AsMo(6)O(24)](9-) subunits connected by three MoO(4) tetrahedra, and a Ag(+) cation is inclosed at the center of the cage and coordinated by two As atoms with a As-Ag-As bond angle of 180° along with three μ(3)-oxo groups from MoO(4) tetrahedra to lead to a trigonal-pyramidal coordination geometry. The compound was also characterized by IR, X-ray photoelectron spectroscopy, fluorescent spectroscopy, and thermogravimetry-differential scanning calorimetry. The stability of [AgAs(2)Mo(15)O(54)](11-) in aqueous solution was investigated by using electronic absorbance spectroscopy and electrospray ionization mass spectrometry. 相似文献
963.
A microporous coordination polymer, namely, [Co(3)(ina)(4)(OH)(C(2)H(5)OH)(3)](NO(3))·C(2)H(5)OH·(H(2)O)(3) (1, or MCF-38, ina = isonicotinate), with 8-connected {Co(3)(OH)} clusters as the structural secondary building units, has been solvothermally synthesized. The hydroxo-centered Co(II) cluster involves multiple active metal sites. The interesting apical ligand substitutions have been directly observed, and the corresponding products of [Co(3)(ina)(4)(OH)(G)(x)(H(2)O)(n)](NO(3))·G·(H(2)O)(m) (1 ? PrOH, G = PrOH, x = 2, n = 1, m = 3; 1 ? BuOH, G = BuOH, x = 2, n = 1, m = 1, and 1 ? MeOH, G = MeOH, x = 3, n = 0, m = 7) have also been obtained by solvothermal syntheses or crystal-to-crystal transformations. High-pressure H(2) adsorption measurement at 77 K reveals that activated 1 can absorb 2.2 wt % H(2) at 5 bar. The relative H(2) absorption at low pressure (86% of the storage capacity at 1 bar) is higher than the corresponding values reported for some typical porous coordination polymers. The magnetic studies of 1 show a dominant antiferromagnetic coupling between Co(II) ions of intra- and inter-cluster. 相似文献
964.
Yong Shen Ai‐Xue Zuo Zhi‐Yong Jiang Xue‐Mei Zhang Hong‐Ling Wang Ji‐Jun Chen 《Helvetica chimica acta》2011,94(1):122-126
Two new C20‐diterpenoid alkaloids, named aconicarchamines A and B ( 1 and 2 , resp.), were isolated from Aconitum carmichaelii. By UV, IR, MS, and 1D‐ and 2D‐NMR analyses, their structures were elucidated as 14,17‐dihydro‐14,17‐dihydroxyajabicine and 15‐O‐acetyllassiocarpine. Compound 1 is the third C20‐diterpenoid alkaloid with the lycoctine skeleton bearing an exocyclic C‐atom at C(14). 相似文献
965.
Deming Huang Shanhong Wan Liping Wang Qunji Xue 《Surface and interface analysis : SIA》2011,43(7):1064-1068
Tungsten trioxide‐incorporated hydrogenated amorphous carbon (WO3/a‐C:H) films have been fabricated on a single‐crystal silicon wafer by liquid phase electrodeposition using methanol as carbon source and tungsten carbonyl as incorporated reagent. The morphology, composition and structure of the films have been investigated by SEM, XPS, Raman scattering spectroscopy, Fourier transform infrared spectroscopy (FTIR) and Transmission electron microscope (TEM), respectively. The effects of WO3 incorporation on the electrical and wetting properties were studied in detail. The characterization results showed that tungsten trioxide nanocrystalline particles with diameters in the range of 10–20 nm were homogenously embedded in the amorphous carbon films. Also, the electrical conductivity and wetting ability of the films were strongly improved due to the contribution of the tungsten trioxide. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
966.
Xue‐Wen Liu Jin‐Can Chen Xia Hu Hong Li Kang‐Cheng Zheng Liang‐Nian Ji 《Helvetica chimica acta》2008,91(7):1374-1388
The ligand pteridino[6,7‐f] [1,10]phenanthroline‐11,13‐diamine (ppn) and its RuII complexes [Ru(bpy)2(ppn)]2+ ( 1 ; bpy=2,2′‐bipyridine) and [Ru(phen)2(ppn)]2+ ( 2 ; phen=1,10‐phenanthroline) were synthesized and characterized by elemental analysis, electrospray MS, 1H‐NMR, and cyclic voltammetry. The DNA‐binding behaviors of 1 and 2 were studied by spectroscopic and viscosity measurements. The results indicate that both complexes strongly bind to calf‐thymus DNA in an intercalative mode, with DNA‐binding constants Kb of (1.7±0.4)?106 M ?1 and (2.6±0.2)?106 M ?1, respectively. The complexes 1 and 2 exhibit excellent DNA‐‘light switch’ performances, i.e., they do not (or extremely weakly) show luminescence in aqueous solution at room temperature but are strongly luminescent in the presence of DNA. In particular, the experimental results suggest that the ancillary ligands bpy and phen not only have a significant effect on the DNA‐binding affinities of 1 and 2 but also have a certain effect on their spectral properties. [Ru(phen)2(ppn)]2+( 2 ) might be developed into a very prospective DNA‐‘light switch’ complex. To explain the DNA‐binding and spectral properties of 1 and 2 , theoretical calculations were also carried out applying the DFT/TDDFT method. 相似文献
967.
Guang‐Yu Yang Wei‐Lie Xiao Ying Chang Rui‐Rui Wang Jian‐Xin Pu Xue‐Mei Gao Chun Lei Yang Lu Yong‐Tang Zheng Han‐Dong Sun 《Helvetica chimica acta》2008,91(10):1871-1878
Three new highly oxygenated nortriterpenoids, wilsonianadilactones A–C ( 1 – 3 ), together with twelve known ones, i.e., 4 – 15 , were isolated from the leaves and stems of Schisandra wilsoniana. Their structures were established by means of extensive analysis of spectroscopic data, and compound 1 was further confirmed by X‐ray crystallographic diffraction. Compounds 1 – 3 showed weak anti‐HIV‐1 activity with EC50 values of 23.5, 55.5, and 66.4 μg/ml, respectively. 相似文献
968.
Ming‐An Chen Xin‐Ming Zhang Rong Huang Xue‐Bin Lu 《Surface and interface analysis : SIA》2008,40(8):1209-1218
The effect of concentration of γ‐aminopropyltriethoxy (γ‐APS) solution on shear strength of adhesive bonding between aluminium sheet and polypropylene (PP) with addition of a certain amount of maleic anhydride‐grafted polypropylene (PP‐g‐MAH) has been investigated. It is shown that the lap shear strength is promoted obviously with pre‐treatment of aluminium sheet by γ‐APS. The maximum strength is obtained at a concentration of 3% γ‐APS solution. With further high concentration of γ‐APS, the lap shear strength decreases. The examination of the separated surfaces by X‐ray photoelectron spectroscopy (XPS) shows that (C?O)2? O? Al and C(?O)? O? Al are formed for adhesive bonding between PP with the addition of 20 wt% PP‐g‐MAH and aluminium sheet without pre‐treatment by γ‐APS, and that the area ratio of C related to oxygen on the separated aluminium side is 33.28%, which is obviously higher than 14% on the polymer side. As for adhesive bonding between PP with the addition of 20% PP‐g‐MAH and 3% γ‐APS pre‐treated aluminium sheet, C(?O)? N? C(?O) and C(?O)? NH are formed. The area ratio of C related to oxygen on the separated polymer side increases to 24.99%. It is proposed that γ‐APS pre‐treatment improves the distribution and shape of PP‐g‐MAH chains in the region adsorbed on the substrate and the region adjacent to this region. The chemical interactions at the interface are also proposed. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
969.
Three polyoxometalates encapsulating high-nuclearity magnetic clusters MFe(5), [As(2)MFe(5)Mo(22)O(85)(H(2)O)](n-) (M = Fe(3+), n = 14; M = Ni(2+) and Mn(2+), n = 15), were synthesized and characterized by single-crystal X-ray diffraction, elemental analysis, infrared spectroscopy, thermogravimetric analysis, and magnetism measurements. The polyanion [As(2)MFe(5)Mo(22)O(85)(H(2)O)](n-) consists of a central MMo(7)O(28) (M = Fe(3+), Ni(2+), and Mn(2+)) fragment and two AsMo(7)O(27) fragments linked together by two trimeric clusters, Fe(2)MoO(μ(2)-O)(2) and Fe(3)(H(2)O), to form a banana-shaped structure with C(1) symmetry. The MMo(7)O(28) and AsMo(7)O(27) units have a similar structure and can be considered as a monocapped hexavacant α-B-Keggin subunit with a central MO(4) group or a central As(III)O(3) group. The polyoxometalates have a low absorption of υ(Mo-O(d)) (925-913 cm(-1)) because most of the Mo atoms in the polyanions have at least two longer Mo-O(d) bonds. The framework of the arsenomolybdates is stable before As(2)O(3) escaping (ca. 300 °C). The analysis of magnetostructural correlations and magnetism measurements indicate the coexistence of ferro- and antiferromagnetic interactions, which give an overall ferromagnetic spin ground state in the compounds. 相似文献
970.
Gold nanoparticles (Au-NPs) with negative charges aggregate in the presence of Arg(6) due to electrostatic interactions resulting in the red-shift of the plasmon absorption. But, after incubation of Arg(6) with trypsin the aggregation of Au-NPs can be prohibited. Accordingly, a newly designed-Au-NPs based colorimetric assay method for trypsin activity is established. Trypsin with a concentration as low as 1.6 ng mL(-1) can be assayed with this new colorimetric assay. This colorimetric label-free assay for trypsin can be performed in aqueous solution and both Au-NPs and Arg(6) are easily accessible. Thus, this assay method is useful for screening inhibitors of trypsin. 相似文献