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921.
A novel double-hydrophilic block copolymer (DHBC) poly(vinyl pyrrolidone)–block–poly(methacrylic acid) (PVP-b-PMAA) was synthesized via reversible addition–fragmentation chain transfer polymerization. The structure of the resulting
copolymer was characterized by 1H nuclear magnetic resonance, and the molecular weight of the block copolymer was determined by gel permeation chromatography.
The study of morphological control of calcium carbonate (CaCO3) has been performed in the presence of the PVP-b-PMAA block copolymer. Various morphologies of CaCO3 particles such as rhombohedral, multilayered, and aggregated with cavities can be produced by varying the copolymer concentrations.
The all-obtained CaCO3 particles were calcite, which was confirmed by either X-ray diffraction or Fourier transform infrared spectra. Such calcium
carbonate/polymer hybrids with complex morphologies may find valuable applications in biomimic mineralization. 相似文献
922.
Chengkuan Qin Jinling Chai Jingfei Chen Yan Xia Xiaoying Yu Jing Liu 《Colloid and polymer science》2008,286(5):579-586
The phase behavior and the solubilization of the microemulsion systems surfactant-like ionic liquids 1-hexadecyl-3-methylimidazolium
bromide (C16mimBr), 1-tetradecyl-3-methylimidazolium bromide (C14mimBr), or 1-dodecyl-3-methylimidazolium bromide (C12mimBr)/alcohol/alkane/brine have been studied with ɛ–β-fish-like phase diagram method at 40 °C and an oil-to-water mass ratio of 1:1. From the ɛ–β-fish-like phase diagram, the physicochemical parameters, such as the mass fraction of alcohol in the hydrophile–lipophile-balanced
interfacial layer (A
S), and the solubilities of ionic liquid (S
O) and alcohol (A
O) in alkane phase, were calculated. The solubilization of the microemulsion system has been discussed based on the ɛ–β-fish-like phase diagram. The smaller the oil molecule, the longer the alcohol chain length, and the larger the NaCl concentration
in water, the larger the solubilization of the microemulsion system. In this paper, the solubilization of the microemulsion
stabilized by both C12mimBr and sodium dodecyl sulfonate (sodium dodecyl sulfate) was also investigated with the ɛ–β-fish-like phase diagram. The unequimolar composite of anionic and cationic surfactants can avoid the sedimentation aroused
by the strong electrostatic attraction, and an obvious synergism effect in solubilization was obtained. 相似文献
923.
Selective adsorption of poly(ethylene oxide) onto a charged surface mediated by alkali metal ions 总被引:1,自引:0,他引:1
Chai L Goldberg R Kampf N Klein J 《Langmuir : the ACS journal of surfaces and colloids》2008,24(4):1570-1576
Using a surface force balance, we have measured normal and shear interactions between mica surfaces across pure water and across 0.1 M aqueous solutions of LiNO3, NaNO3, KNO3, and CsNO3, both prior to adding polymer and following addition of 1.5 x 10(-4) w/w poly(ethylene oxide) (PEO, Mw = 170 kD) and overnight incubation. Our results reveal that while the PEO adsorbs strongly from the KNO3 and CsNO3 solutions, unexpectedly it does not adsorb at all from the LiNO3 and NaNO3 salt solutions. We attribute this to the different nature of the hydration layers about the alkali metal ions: these favor liganding to the negatively charged mica surface of the etheric -O- group on the ethylene oxide monomer for the case of the more weakly hydrated K+ and Cs+, but not for the case of Na+ or Li+ with their more strongly bound water. A simple model relating the electrostatic energy changes occurring upon such liganding to the experimentally measured hydration energies of the different alkali metal ions supports this attribution. 相似文献
924.
Zhao Q Zheng J Chai B Pollack GH 《Langmuir : the ACS journal of surfaces and colloids》2008,24(5):1750-1755
Colloidal crystals were formed from microsphere suspensions via a simple and novel approach using gel beads. The microspheres self-assembled not only around each bead but also between beads in an ordered pattern. The crystals shrunk under incident light, with the effect of blue (wavelength 450 to 500 nm) being the most profound. The results shed new light on the fundamental issue of self-assembly and colloid science. 相似文献
925.
Diandou Xu Zhi Zhang Qiaolong Jiang Yifan Li Zhifang Chai 《Journal of Radioanalytical and Nuclear Chemistry》2008,278(2):241-245
Abstract
Passive air samplers (polyurethane foam disks) were deployed at 25 urban sites and 66 rural sites over the period of July
to October 2005, partly between October 2005 and January 2006 for about 120 days across China, and analyzed for extractable
organo-chlorine /-bromine /-iodine (EOCl/EOBr/EOI) and polychlorinated biphenyls (PCBs) using hybrid neutron activation analysis
(NAA) combined with gas chromatographymass spectrometry (GC-MS). The average concentration of EOCl, EOBr, EOI and ΣPCBs among
all the sites were 173.7, 3.5, 1.0 and 0.74 ng/d, respectively. Higher values of EOCl/Br/I and PCBs were detected in the areas
of high usage and high emission, which were linked to relatively high-income areas in China, while lower in the west ill-developed
region of China, which indicated that these pollutants mainly came from industrial pollution. Higher EOCl contents in traffic
areas stated that the exhaust emission from vehicle was another main source of organochlorines in the air. The relative proportions
of the known organochlorines (84 PCB congeners) to total EOCl were 0.02–3.0%, which implied that most of EOCl measured in
air were unknown. 相似文献
926.
A reliable and rapid method based on rapid-resolution liquid chromatography-diode array detection (RRLC-DAD) and electrospray ionization time-of-flight mass spectrometry (ESI-TOF/MS) has been developed for the isolation and characterization of multiple constituents in the root of Stellera chamaejasme L., which was extracted by sonication with methanol in an optimized procedure. Separation of the multiple constituents was achieved on an Agilent Zorbax XDB-C18 (50x3.0 mm i.d.; 1.8 microm) column using a gradient elution at a flow rate of 0.4 mL/min. The detection wavelength was 210 nm. Mass spectra were acquired in both positive and negative modes. A formula database of the known chemical constituents in the root of Stellera chamaejasme L. was established by an Agilent software. Twenty-two obvious peaks appeared in the total ion chromatogram and nine of them were characterized by TOF/MS. The RRLC-DAD and ESI-TOF/MS method with ultrasonic extraction would be useful for rapid and effective characterization of chemical constituents in the root of Stellera chamaejasme L. 相似文献
927.
Two new copper(II) complexes of [Cu(Ofloxacin)(phen)(H2O)] · (NO3) · 2H2O and [Cu(Levofloxacin)(phen)(H2O)] · (NO3) · 2H2O were obtained and their structures were studies. Both ligands and complexes were assayed against gram-positive and gram-negative
bacteria by the in vitro doubling dilutions method. The inhibitory effect of the ligands and complexes on the leukemia HL-60
cell line were measured with the MTT assay method and the liver cancer HePG-2 cell line measured by the SRB method. The results
indicated that the complexes have stronger inhibitory effect on HL-60 than on HePG-2. The complex [Cu(Levofloxacin)(phen)(H2O)] · (NO3) · 2H2O (I) has stronger effect on HL-60 than the complex (Cu(Ofloxacin)(phen)(H2O)] · (NO3) · 2H2O (II).
The text was submitted by the authors in English. 相似文献
928.
A novel enzyme immobilization technique based on thionine‐bovine serum albumin conjugate (Th‐BSA) and gold colloidal nanoparticles (nano‐Au) was developed. Thionine was covalently bound onto the BSA film with glutaraldehyde(GA) as cross‐linker to achieve Th‐BSA conjugate. The free amino groups of thionine were then used to attach nano‐Au for the immobilization of horseradish peroxidase (HRP). Such nano‐Au/Th‐BSA matrix shows a favorable microenvironment for retaining the native activity of the immobilized HRP and thionine immobilized in this way can effectively shuttle electrons between the electrode and the enzyme. The proposed biosensor displays excellent catalytic activity and rapid response for H2O2. The linear range for the determination of H2O2 is from 4.9×10?7 to 1.6×10?3 M with a detection limit of 2.1×10?7 M at 3σ and a Michaelies‐Menten constant K value of 0.023 mM. 相似文献
929.
[reaction: see text] An efficient two-pot, asymmetric synthesis of benzothiadiazine-substituted tetramic acids is reported. Starting from commercially available alpha-amino acids or esters, reductive amination followed by a novel one-pot amide bond formation/Dieckmann cyclization provided the desired products in high yield and optical purity. An analogous solid-phase approach to the same targets is also presented. These compounds were found to be potent inhibitors of hepatitis C virus RNA-dependent RNA polymerase. 相似文献
930.