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991.
Preparation and adsorption properties of crosslinked polystyrene-supported low-generation diethanolamine-typed dendrimer for metal ions 总被引:1,自引:0,他引:1
Two novel chelating resins, polystyrene supported G1.0 diethanolamine-typed dendrimer (PS-DEA) and G2.0 diethanolamine-typed dendrimer (PS-(DEA)2), were prepared by anchoring low-generations diethanolamine-typed dendrimer into crosslinked polystyrene in this paper. Fourier transform-infrared spectra (FTIR), scanning electron microscopy (SEM) and elemental analysis were employed to character their structures. The results of adsorption for metal ions showed that the resins had good adsorption capacities for Cu2+, Ag+ and Hg2+, especially PS-DEA for Cu2+. The adsorption kinetics and adsorption isotherms of PS-DEA for Cu2+ and PS-(DEA)2 for Hg2+ were studied. The results showed that the adsorption kinetics of the two resins can be modeled by pseudo second-order rate equation wonderfully and Langmuir and Freundlich equations could well interpret the adsorption of PS-(DEA)2 for Hg2+ and PS-DEA for Cu2+, respectively. The adsorption mechanism of the resins for Cu2+ was confirmed by X-ray photoelectron spectroscopy (XPS). 相似文献
992.
Qu Y Ma W Bian X Tang H Tian W 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,63(2):272-275
The structure and harmonic vibrations of Ga(n)N(n) (n = 3-10) clusters have been investigated using the B3LYP (Becke 3-parameter-Lee-Yang-Parr) density functional theory. All structures are found to be cumulenic D(nh) rings (equal bonds, alternating angles), with one intense out of plane mode and three infrared-active degenerate modes, of which the highest one is extremely intense and asymptotically increases to 1029 cm(-1) for n = 10. Comparisons with C2n, B(n)N(n), and Al(n)N(n) clusters, the structure and bonding type for the Ga(n)N(n) (n=3-10) clusters are consistent with those of the C2n (n = 3, 5, 7, ...) clusters, the B(n)N(n) (n = 3-10), and Al(n)N(n) (n = 3-9) clusters. 相似文献
993.
A new ultraviolet (UV) labeling reagent, p-acetamidobenzenesulfonyl fluoride (PAABS-F), was designed and synthesized to label and determine the amino acids by capillary electrophoresis (CE) with diode-array detector (DAD). PAABS-F is very stable and easy to synthesize. It reacted with primary or secondary amino acids very quickly under facile conditions to give corresponding derivatives in high yield with excellent sensitivity and stability. No by-products were observed in amino acid derivatives when stored at room temperature under natural daylight for at least 7 days. Both amino acids standard solution and real samples reacted with this new UV labeling reagent smoothly to form high UV-absorption derivatives. The labeled 20 standard amino acids were efficiently separated by CE and the mass detection limits (S/N = 3) were ranged from 59.3 fmol for l-tryptophan to 1.70 pmol for l-histidine. 相似文献
994.
Liu J Shen M Zhang Y Li G Khodabocus A Rodriguez S Qu B Farina V Senanayake CH Lu BZ 《Organic letters》2006,8(16):3573-3575
[reaction: see text] A one-step method was developed for elaboration of a variety of polycyclic indole skeletons via a novel palladium-catalyzed intramolecular indolization of 2-chloroanilines bearing tethered acetylenes. This novel intramolecular indolization method unveils an unusual syn amidopalladation pathway of a tethered alkyne. 相似文献
995.
A time-resolved confocal fluorescence spectroscopy system is built to measure the fine structure and localized biochemistry of epithelial tissue. It is found that the autofluorescence excited at 405 nm is sensitive to the cellular metabolism and can be used to sense the metabolic status of epithelial tissue. The decay of autofluorescence excited at 405 nm can be accurately fitted with a dual-exponential function consisting of short lifetime (0.4-0.6 ns) and long lifetime (3-4 ns) components. The ratio of the amplitudes of the two components provides information on the fine structure of epithelial tissue. We demonstrate that the combined depth- and time-resolved measurements with single excitation can potentially provide accurate information for the diagnosis of tissue pathology. 相似文献
996.
Virginie Daru Marie-Christine Duluc Olivier Le Maître Damir Juric Patrick Le Quéré 《Comptes Rendus Mecanique》2006,334(1):25-33
A model for the simulation of boiling flow with phase change in a closed cavity is presented. A front-tracking method is used to deal with the liquid–vapor interface. The liquid phase is incompressible while the vapor phase is weakly compressible and obeys to the perfect gas law. This model can deal with large density ratio () flows while accounting for the saturation curve. Computations are performed on a 1D validation case, idealizing a pressure cooker. Results are compared with a low Mach number approximation. To cite this article: V. Daru et al., C. R. Mecanique 334 (2006). 相似文献
997.
A new visco-elastic contact model of traveling wave ultrasonic motor (TWUSM) is proposed. In this model, the rotor is assumed to be rigid body and the friction material on stator teeth surface to be visco-elastic body. Both load characteristics of TWUSM, such as rotation speed, torque and efficiency, and effects of interface parameters between stator and rotor on output characteristic of TWUSM can be calculated and simulated numerically by using MATLAB method based on this model. This model is compared with that one of compliant slider and rigid stator. The results show that this model can obtain bigger stall torque. The simulated results are compared with test results, and found that their load characteristics have good agreement. 相似文献
998.
This research develops an analytical model (using Stroh's formalism) to predict the affect of applied stress on the wave speed and the polarization of Rayleigh surface waves. Simulation results are then used to demonstrate that the polarization of a Rayleigh wave (which is reference-free) could be more sensitive than wave speed as an indicator of the state of stress. 相似文献
999.
The Ramanujan Journal - Suppose that $$\lambda _1, \lambda _2, \lambda _3, \lambda _4$$ are positive real numbers and $$\frac{\lambda _1}{\lambda _2}$$ is irrational and algebraic. Let $$\mathcal... 相似文献
1000.
The Boros-Moll polynomials arise in the evaluation of a quartic integral. The original double summation formula does not imply
the fact that the coefficients of these polynomials are positive. Boros and Moll proved the positivity by using Ramanujan’s
Master Theorem to reduce the double sum to a single sum. Based on the structure of reluctant functions introduced by Mullin
and Rota along with an extension of Foata’s bijection between Meixner endofunctions and bi-colored permutations, we find a
combinatorial proof of the positivity. In fact, from our combinatorial argument one sees that it is essentially the binomial
theorem that makes it possible to reduce the double sum to a single sum. 相似文献