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41.
Poly(lactic acid)/organo-montmorillonite nanocomposites were prepared by melt intercalation technique. Maleic anhydride-grafted
ethylene propylene rubber (EPMgMA) was added into the PLA/OMMT in order to improve the compatibility and toughness of the
nanocomposites. The samples were prepared by single screw extrusion followed by compression molding. The effect of OMMT and
EPMgMA on the thermal properties of PLA was studied. The thermal properties of the PLA/OMMT nanocomposites have been investigated
by using differential scanning calorimeter (DSC) and thermo-gravimetry analyzer (TG). The melting temperature (T
m), glass transition temperature (T
g), crystallization temperature (T
c), degree of crystallinity (χc), and thermal stability of the PLA/OMMT nanocomposites have been studied. It was found that the thermal properties of PLA
were greatly influenced by the addition of OMMT and EPMgMA. 相似文献
42.
Acoustic wave detection of various underivatized amino acids that were hydrodynamically introduced into and electrokinetically migrated along a capillary tube has been achieved. The detection principle is based on the measurement of the ultrasonic absorption and density change of the aqueous amino acid samples as they pass by the detection zone. Acoustic wave detection of underivatized leucine was obtained in the ultrasonic frequency range of 100 kHz to 20 MHz. This was accomplished by measuring the insertion loss from the vector ratio of the signal voltage to the source voltage obtained at the generating and receiving piezoelectric transducers. Linear concentration dependence of the insertion loss of underivatized leucine was established. The effects of capillary internal diameter, capillary geometry (square and circular), buffer concentration, buffer pH and acoustic wave frequency on the insertion loss were investigated. Subsequently, separations of underivatized amino acids (leucine/histidine and leucine/tryptophan) were performed under different buffer conditions and different capillary geometry. 相似文献
43.
LH Tong S Clifford A Gomila S Duval L Guénée AF Williams 《Chemical communications (Cambridge, England)》2012,48(79):9891-9893
Square self-assemblies are obtained from dirhodium(ii) tetracarboxylate complexes using an isonicotinate-type ligand to act as an equatorial ligand to one dirhodium unit and an axial ligand to another. It is shown that the supramolecular squares are formed selectively out of a number of possible compounds in the dynamic carboxylate exchange library. 相似文献
44.
45.
Tong LH Pascu SI Jarrosson T Sanders JK 《Chemical communications (Cambridge, England)》2006,(10):1085-1087
Suzuki and Sonogashira couplings have been used in short and efficient sequences to give access to a new family of porphyrin trimers on a practical scale. 相似文献
46.
Davidson GJ Tong LH Raithby PR Sanders JK 《Chemical communications (Cambridge, England)》2006,(29):3087-3089
Aluminium(III) porphyrin-carboxylate complexes, including a porphyrin pentamer, have been characterised by NMR spectroscopy, MALDI spectrometry and single crystal X-ray diffraction; these complexes can also be coordinated by a sixth, nitrogenous, ligand to the aluminium(III) centre. 相似文献
47.
Lam KL Ishitsuka Y Cheng Y Chien K Waring AJ Lehrer RI Lee KY 《The journal of physical chemistry. B》2006,110(42):21282-21286
While pore formation has been suggested as an important step in the membrane disruption process induced by antimicrobial peptides, membrane pore formation has never been directly visualized. We report on the dynamics of membrane disruption by antimicrobial peptide protegrin-1 (PG-1) on dimyristoyl-sn-glycero-phosphocholine-supported bilayer patches obtained via atomic force microscopy. The action of PG-1 is found to be concentration-dependent. At low PG-1 concentrations (1 < [PG-1] < 4 microg/mL), the peptide destabilizes the edge of the membrane to form fingerlike structures. At higher concentrations, PG-1 induces the formation of a sievelike nanoporous structure in the membrane. The highest degree of disruption is attained at concentrations >or=20 microg/mL, at which PG-1 disrupts the entire membrane, transforming it into stripelike structures with a well-defined and uniform stripe width. This first direct visualization of these membrane structural transformations helps elucidate the PG-1-induced membrane disruption mechanism. 相似文献
48.
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50.
Oil-induced anomalous thermoresponsive viscoelasticity in fluorinated surfactant systems 总被引:1,自引:0,他引:1
Sharma SC Rodríguez-Abreu C Shrestha LK Aramaki K 《The journal of physical chemistry. B》2007,111(42):12146-12153
We have studied the rheology and structure of a mixed nonionic fluorinated surfactant, perfluoroalkyl sulfonamide ethoxylate, C(8)F(17)SO(2)N(C(3)H(7))(CH(2)CH(2)O)(n)H abbreviated as C(8)F(17)EO(10), and perfluorodecalin (C(10)F(18)) or perfluoropolyether oil, (C(3)F(6)O)(n)COOH, in an aqueous system using rheometry and small-angle X-ray scattering (SAXS) techniques. In the absence of oil, the viscosity of surfactant solutions (10 and 15 wt %) first decreases slightly and then more strongly with temperature. Addition of a small amount of fluorinated oil to the wormlike micellar solution disrupts the network structure and decreases the viscosity sharply at lower temperature indicating a rod-sphere transition. The trend of the viscosity curve changes gradually and an anomalous viscosity maximum as a function of temperature appears. It is found that perfluoropolyether oil decreases the viscosity more effectively than perfluorodecalin. The generalized indirect Fourier transformation (GIFT) analysis of the SAXS data confirmed the formation of long rod-like particles in an oil-free, surfactant/water system at 20 degrees C. Addition of a trace amount of fluorinated oils induces modulation in the structure of the micelles and eventually short rods or spherical particles are formed. The decreasing trend in the viscosity with oil concentration is thus attributed to the microstructure changes induced by the added oils. 相似文献