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621.
Maleated polyolefins (MaPOs) such as maleated ethylene propylene copolymers or polyisobutylene terminated at one end with a succininic anhydride can be used as polymeric dispersants in engine oils after reaction with polyamines while unmodified EP copolymers improve the viscosity index of oils. MaPOs can also be labeled with pyrene derivatives to generate pyrene‐labeled polyolefins (PyLPOs) as fluorescent mimics of oil additives and pyrene excimer fluorescence (PEF) can be applied to probe their behavior in solution. This review describes new methodology that was recently implemented to characterize the complex fluorescence signal emitted by PyLPOs by using steady‐state and time‐resolved fluorescence. This methodology enables one to gain quantitative information about the level of clustering of the succinic pendants along a maleated polyolefins and intra‐ and intermolecular aggregation of polyolefins in solution. Such information is relevant to scientists aiming to characterize polymeric oil additives used in engine oil. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 7–18 相似文献
622.
利用激光等离子体软X射线激励,观察到一种新型离子准分子-KrF离子准分子的真空紫外连续谱,其辐射中心波长位于148nm附近,并在实验和理论上对其动力学过程进行分析。 相似文献
623.
Xenon porometry is a novel method used for characterizing porous materials by the (129)Xe nuclear magnetic resonance of xenon gas. With the method, the diffusion of gas is slowed down by immersing the material in a medium, which can be in liquid or solid state during measurements. Because of slow diffusion, the signal of a xenon atom is characteristic of the properties of only one pore, and the composite signal of all atoms represents the distribution of properties. The method is especially applicable for determining pore size distribution because the chemical shifts of two different xenon signals (one from liquid and the other from gas pockets in solid) are dependent on pore size. Therefore, the shapes of these signals represent pore size distribution function. In addition, the porosity of the material can be determined by comparing the intensities of two signals. This article focuses on describing xenon signals observed from gas pockets in a solid medium, which has turned out to be most convenient for pore size determination. 相似文献
624.
Miyuki Narita Fumio Hamada 《Journal of inclusion phenomena and macrocyclic chemistry》2002,44(1-4):335-340
Fluorogenic active host labeled at the upper and lower rims of -cyclodextrin, namely, mono-3A-deoxy-3A-pyrenebutylamido-6X-O-mono-pyrenebutylate-mono-altro--cyclodetrin (mixture
-1,X = A, B, C, D, E, F, G, or H), has been synthesized in order to investigate their host-guest complexation with steroidal compoundsusing fluorescence spectra. Monomer and excimer fluorescence was observed for mixture host. Inclusion of a guest molecule in the cyclodextrin cavity resultedin increased monomer fluorescence and decreased excimer fluorescence. The extent of monomerand excimer fluorescence variations ofmixture -1 with the guestwas used as an indication for the sensing ability. The guest inducedfluorescence changes were measured for 10-7 M solutions of mixture
-1.The values I/I
0
, where I
0
and I are fluorescence intensities in the absence and presence of a guest, respectively, and I is I
0
- I, were then used to describe the sensing ability. 相似文献
625.
626.
P. M. Larionov A. N. Malov A. M. Orishich V. S. Shchukin 《Journal of Applied Spectroscopy》1997,64(4):557-559
Investigations of laser-induced fluorescence spectra for human cardiac valve tissue with calcinosis are performed as compared
to similar spectra of bone and myocardial tissue of an animal that are excited by an excimer laser with a 248-nm wavelength.
It is shown that a healthy tissue has a laser-induced fluorescence maximum in the region of 300–400 nm which corresponds to
protein tissue luminescence. For tissue affected by calcinosis, the laser-induced fluorescence spectra differ significantly
from the spectra of healthy tissue and have a maximum in the region of 400–500 nm. The obtained results offer the prospects
for using laser-induced fluorescence to diagnose tissue with calcinosis in open-heart surgery.
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 4, pp. 539–541, July–August, 1997. 相似文献
627.
稀有气体卤化物离子准分子XUV跃迁参数计算 总被引:3,自引:0,他引:3
利用推导的修正的Rittner势,采用ab initio高斯80程序,首次计算了稀有气体卤化物势能曲线、光谱常数、辐射波长及相关的能级寿命,自发发射,受激发射系数和增益截面,从而给出了产生XUV激光的有关参数和依据,初步认为稀有气体卤化物离子准分子可能是获得XUV波段激光的优秀侯选者。 相似文献
628.
Mirochnik A. G. Bukvetskii B. V. Fedorenko E. V. Karasev V. E. 《Russian Chemical Bulletin》2004,53(2):291-296
The crystal structures and spectral-luminescence properties of anisoylbenzoylmethanatoboron difluoride (1) and dianisoylmethanatoboron difluoride (2) were studied in the solid state and in solution. The structural features of compounds 1 and 2 are responsible for the occurrence of a new type of excimers in solutions, which differs from that observed in the crystalline state. 相似文献
629.
A simple and effective photoelectric current measuring circuit is introduced, which is used to analyze the energy characteristics of the 157 nm excimer laser. Comparisons are carried out for different grounding position, different distance between the electrodes and measuring apparatus. In addition, the circuit is used to detect the energy characteristics of the 157 nm excimer laser. The experimental results are useful for the actual photoelectric effect measuring work. 相似文献
630.
The optical characteristics of a UV broadband lamp that was excited by a longitudinal glow discharge and operated on Kr—Br2—I2, Xe—Br2—I2, and Kr—Xe—Br2—I2 mixtures are investigated. The interelectrode spacing in the lamp is 10 cm, the inner diameter of a discharge tube being
14 mm. The current-voltage characteristics, the emission spectra of the plasma, and the dependence of the intensity of spectral
lines (the amplitude of radiation bands) on the power that was pumped into the plasma based on mixtures of various compositions
and pressures, as well as the radiation power in the spectral range from 200 to 390 nm, are studied.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 840–842, November–December, 2005. 相似文献