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81.
Core–Shell Materials: Combination of HAADF‐STEM and ADF‐STEM Tomography for Core–Shell Hybrid Materials (Part. Part. Syst. Charact. 12/2015)
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82.
Free‐radical homopolymerization and copolymerization of phenacyl methacrylate (PAMA) with methyl methacrylate (MMA) was done using 2,2′‐azobis(isobutyronitrile) (AIBN) as the initiator in 1,4‐dioxane at 60°C. 1H‐NMR and FT‐IR spectroscopy confirmed the existence of OCH2 and CH signals and unsaturated structure and CN stretch at the chain end of low molecular weight poly(phenacyl methacrylate)[poly(PAMA)], respectively. The six‐membered ring with both ester and ether at the end group was detected by 1H‐NMR. In the poly(PAMA), the end groups formed due to chain transfer reactions were found in large concentrations. The mechanism of the formation of end groups has been presented. The behavior of free radical polymerization of PAMA was compared with that of phenoxycarbonylmethyl methacrylate (PCMMA). The molecular weight distribution of the homo and copolymers was determined using gel permeation chromatography. Thermal properties of the polymers were determined using differential thermal analysis (DTA) and thermogravimetric analysis (TGA). 相似文献
83.
Four new dendritic structures carrying perfluorobenzyl bromide on the surface and calix[4]arene and cyclam as a core were synthesized by using the convergent approach. These structures were determined by 1H-NMR, 13C-NMR and elemental analysis. Thermal stabilities of fluorinated dendritic structures were investigated using thermogravimetric analysis. Activation energies and thermal degradation of the structures were calculated with the Ozawa method. Thermogravimetric analysis of the dendritic structures reveals that the thermal stability of the structures increases with an increase in the number of the fluorine atoms. Dendritic structures synthesized were tested for their antimicrobial activity against, Salmonella typhimurium NRRLB, Micrococcus luteus, Pseudomonas aeruginosa, Enterococcus fecalis ATCC-29212, Bacillus cereus ATCC-117787, Klepsiella pneumoniae, Bacillus subtilis NRS-744 and Proteus vulgoris, Yersinia enterolitica, Saccharomyces cereviciae. The structures showed comparative activity against different strains of bacteria. Biological activities of the dendritic structures were seen to increase with an increase in fluorination and the number of nitrogen atoms. 相似文献
84.
Zal?U’yun?Wan?MahmoodEmail author Che?Abd.?Rahim?Mohamed Abdul?Kadir?Ishak Nita?Salina?Abu?Bakar Kamaruzzaman?Ishak 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(3):953-959
Marine sediment cores were collected from two stations at East Malaysia coastal waters on June 2004. Activity concentrations
of 210Pb in sediment core were ranged from 11 Bqkg−1 to 84 Bqkg−1 dry wt. for SR 01 and 4 Bqkg−1 to 66 Bqkg−1 dry wt. for SB 03. Meanwhile, activity concentrations of 226Ra in sediment core were varied significantly depending on the sampling location of SR 01 and SB 03 with ranged 17–26 Bqkg−1 dry wt. and 8–11 Bqkg−1 dry wt., respectively. The activity ratios of 210Pb/226Ra were no significantly different at all sampling stations with an average of 1.78. Refer to the entire results; the activities
of 210Pb and 226Ra were higher at station SR 01 than station SB 03, but contrast with ratio of 210Pb/226Ra. The reasons of different 210Pb and 226Ra activity concentration and distribution of their ratios were strictly related to their half lives, environment origin,
potential sources and behavior. 相似文献
85.
We investigate the structure of singular Calabi–Yau varieties in moduli spaces that contain a Brieskorn–Pham point. Our main tool is a construction of families of deformed motives over the parameter space. We analyze these motives for general fibers and explicitly compute the L-series for singular fibers for several families. We find that the resulting motivic L-functions agree with the L-series of modular forms whose weight depends both on the rank of the motive and the degree of the degeneration of the variety. Surprisingly, these motivic L-functions are identical in several cases to L-series derived from weighted Fermat hypersurfaces. This shows that singular Calabi–Yau spaces of non-conifold type can admit a string worldsheet interpretation, much like rational theories, and that the corresponding irrational conformal field theories inherit information from the Gepner conformal field theory of the weighted Fermat fiber of the family. These results suggest that phase transitions via non-conifold configurations are physically plausible. In the case of severe degenerations we find a dimensional transmutation of the motives. This suggests further that singular configurations with non-conifold singularities may facilitate transitions between Calabi–Yau varieties of different dimensions. 相似文献
86.
Laachachi A Ball V Apaydin K Toniazzo V Ruch D 《Langmuir : the ACS journal of surfaces and colloids》2011,27(22):13879-13887
The present paper relies on the original idea to design multifunctional coatings, and in particular highly efficient intumescent flame retardant coatings, based on the diffusion of polyphosphates (PSPs) in exponentially growing "layer-by-layer" films made from montmorillonite (MMT) and poly(allylamine) (PAH). Here, we used polyphosphates as an acid source, polyallylamine as both a carbon source and a swelling agent, and finally clays to reinforce the intumescent char strength and also for their oxygen barrier property. The coatings made from the alternated deposition of n = 60 layer pairs of PAH and MMT reach a considerable thickness of ~18 μm with well-defined ordering of the MMT in the direction parallel to the substrate. Structural, morphological, mechanical, gas barrier, and fire resistance properties of these films have been studied. Excellent oxygen barrier properties and extraordinary fire resistance properties are demonstrated based on the basis of a strong increase of the time to ignition and on a decrease of the heat release rate of polylactide substrates during mass loss calorimeter tests. This new and innovative intumescent flame retardant system based on (PAH-MMT)(n)-PSP coatings is a promising universal treatment for current polymeric materials. 相似文献
87.
Yekeler E Suleyman E Tunaci A Tunaci M Balci NC Onem K Tunc M Acunas G 《Magnetic resonance imaging》2004,22(9):1193-1199
Contrast-enhanced 3D MR voiding urethrography (CE 3D MRVU) was performed on 5 healthy volunteers and 18 patients with urethral disease. After intravenous injection of 0.3 ml/kg gadolinium, the images of the three consecutive acquisitions of the 3D MRVU technique were obtained during voiding. The raw data were reconstructed on all patients for visual analysis. The image quality of the volunteers was technically sufficient to demonstrate normal urethral anatomy. Contrast-enhanced 3D MR voiding urethrography of the urethral strictures was compared with conventional retrograde urethrography (n = 10) and urethroscopy (n = 12). The urethral pathologies including strictures and other obstructive causes of impaired urethral flow were correctly identified on CE 3D MRVU. 相似文献
88.
89.
An innovative, powerful, efficient and relatively rapid method was developed to synthesise various β-aminoketone derivatives from cyclohexanone, substituted aromatic amines and aromatic or hetero-aromatic aldehydes via ultrasound-assisted
direct-type catalytic Mannich reaction using bismuth(III) triflate in water. Good yields of the desired β-aminoketones were obtained at room temperature by ultrasound-assisted reaction within 1–2 h. The major advantages of the
proposed method are undemanding conditions, easy operation, low toxicity, shorter reaction time, anti selectivity and higher
yields in comparison with conventional methods. 相似文献
90.