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81.
Yuzhu Zhao Jizhu Zhou Xiaohui Xu Wenbin Liu Jingying Zhang Minghong Fan Jinben Wang 《Colloid and polymer science》2009,287(2):237-241
We present the synthesis and the characterization of a new class of modified polyacrylamides (MPAM) with the unusual trait
of strong emulsification ability, viscosity enhancement capacity, and significant salt tolerance. Besides, the synthesized
polymers have the peculiar aggregation behaviors in aqueous solution. The synthesis was carried out by polymerizing the monomers
such as acrylamide (AM), acrylic acid (AA), unsaturated amphiphilic functional moieties, and high steric hindrance functional
units. Their aggregation behaviors were investigated by using a scanning electron microscope (SEM). The emulsion, formed by
10 ml of MPAM (with the polymer concentration of 1,000 mg/L) and the 10 ml of crude oil, was very stable, which indicates
that the synthesized polymers have unique emulsification properties. The strong hydrophobic interaction between molecules
and the three-dimensional network formed in aqueous solution were exhibited by the experimental results of steady fluorescence
and SEM experiments. It could be concluded that the performance of polymers for enhanced oil recovery (EOR) can be remarkably
enhanced by introducing functional monomers to polymer backbone, which allows the new class of modified polymers to have more
promising application in enhanced oil recovery. 相似文献
82.
The primary structure of 3'-imino[60]fulleryl-3'-deoxythymidine ions is studied using mass spectrometry both in the positive and negative modes. Interaction between the subunits is discussed using collision-induced dissociation (CID) spectra. Collisional activation with argon of the sodiated cations leads to the cleavage of the glycosidic bond and the transfer of a radical hydrogen from the deoxyribose to the thymine. The sodiated thymine is the only fragment observed for low collision energies in the positive mode. In the negative mode, two different ionization mechanisms take place, reduction and deprotonation in the presence of triethylamine. The 2.7 eV electron affinity of C60 and its huge cross section compared to the small cross section and predicted 0.44 eV electron affinity of the thymidine subunit most likely localize the radical electron on the fullerene. On the other hand, deprotonation of the 3'-azido-3'-deoxythymidine (AZT) is known to occur in N-3, the most acidic site of the nucleobase. Consequently, deprotonation causes the negative charge to be initially localized on the thymine. Both types of parent anions give the radical anion C60*- as fragment. The other fragments detected are the dehydrogenated 3'-imino[60]fulleryl-3'-deoxyribose anion, C60NH2-, C60N- and C60H-. Since in negative ion mass spectrometry all fragments include the [60]fullerene unit, this suggests that the fragmentation is driven by the electron affinity of the [60]fullerene, likely responsible for a charge transfer between the deprotonated thymine and the C60. 相似文献
83.
According to the Trial of Org 10172 in Acute Stroke Treatment, ischemic stroke is classified into five subtypes. However, the predictive biomarkers of ischemic stroke subtypes are still largely unknown. The utmost objective of this study is to map, construct and analyze protein-protein interaction (PPI) networks for all subtypes of ischemic stroke, and to suggest the predominant biological pathways for each subtypes. Through 6285 protein data retrieved from PolySearch2 and STRING database, the first PPI networks for all subtypes of ischemic stroke were constructed. Notably, F2 and PLG were identified as the critical proteins for large artery atherosclerosis (LAA), lacunar, cardioembolic, stroke of other determined etiology (SOE) and stroke of undetermined etiology (SUE). Gene ontology and DAVID analysis revealed that GO:0030193 regulation of blood coagulation and GO:0051917 regulation of fibrinolysis were the important functional clusters for all the subtypes. In addition, inflammatory pathway was the key etiology for LAA and lacunar, while FOS and JAK2/STAT3 signaling pathways might contribute to cardioembolic stroke. Due to many risk factors associated with SOE and SUE, the precise etiology for these two subtypes remained to be concluded. 相似文献
84.
Conductance measurements of 12 quaternary ammonium salts in propylene carbonate (PC) have been made at 25°C. The cations were either tetramethylammonium, tetraethylammonium, or tetra-n-butylammonium, and the concentrations of salt varied from about 2×10–4 to 5×10–3
M. The data were analyzed by the equation of Pitts. The results showed that the benzoate, nitrobenzoate, and pentachlorophenolate salts are completely dissociated. The nitrophenolate, chlorophenolate, methylsulfonate, and nitrate salts are only slightly associated (K
A
from 2.5 to 6.5), while the acetate, phenylacetate, and nitrophenolate salts display somewhat more extensive association, with ionpair association constants from 17 to 45. Limiting molar conductances for the anions were derived. The factors affecting ionic mobilities in this dipolar aprotic solvent are discussed.On leave 1973–1975 from the University of Gdask, Poland. 相似文献
85.
Richard M. Kettler Donald A. Palmer David J. Wesolowski 《Journal of solution chemistry》1995,24(1):65-87
The first and second molal dissociation quotients of succinic acid were measured potentiometrically with a hydrogen-electrode, concentration cell. These measurements were carried out from 0 to 225°C over 25° intervals at five ionic strengths ranging from 0.1 to 5.0 molal (NaCl). The dissociation quotients from this and two other studies were combined and treated with empirical equations to yield the following thermodynamic quantities for the first acid dissociation equilibrium at 25°C: log K1a=–4.210±0.003; H
1a
0
=2.9±0.2 kJ-mol–1; S
1a
0
=–71±1 J-mol–1-K–1; and C
p1a
0
=–98±3 J-mol–1-K–1; and for the second acid dissociation equilibrium at 25°C: log K2a=–5.638±0.001; H
2a
0
= –0.5±0.1 kJ-mol–1; S
2a
0
=–109.7±0.4 J-mol–1-K–1; and C
p2a
0
= –215±8 J-mol–1-K–1. 相似文献
86.
Summary The interaction of some benzene and naphthalene derivatives with sodium dodecyl sulphate, hexadecyltrimethylmmonium bromide and polyoxyethylene [23] dodecanol micelles has been evaluated by high operformance liquid chromatography using micellar mobile phases. The micelle-solute association constants have been obtained for the compounds investigated. Good correlation between free energy of transfer for water-micelles and for octanol-water has been observed. 相似文献
87.
A PCM continuum model, at the B3LYP, B3P86, and B3PW91 three‐parameter hybrid DFT methods with 6‐311G** basis set, is used to study the bond dissociation energies (BDEs) of benzyl nitrites. Compared the computed results with the experimental values, it is noted that B3PW91 functional is the best method to compute the BDEs of benzyl nitrites. The solvent and substituent effects on the BDEs of the O? NO bond are analyzed, and it is shown that the BDE of the O? NO bond decreases with the increment of the Hammett constants of substituent groups on benzene for benzyl nitrites except C6H5CH2O? NO. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 相似文献
88.
对17种酚类化合物用半经验量子化学方法AM1计算了表征O-H解离能的参数△HOF值,即酚类化合物与其经抽氢反应产生的自由基生成热之差。经过与实验测定的17种酚类化合物的O-H解离能比较,评价了AM1方法在计算△HOF值方面的有效性。发现AM1计算的△HOF值与O-H解离能有很好的相关性(γ=0.9495),优于经验方法,比如加和规则对O-H解离能的预测。虽然AM1方法在计算间位取代对O-H解离能的贡献方面是无效的,但将用于计算解离能类的参数以预测抗氧化剂活性还是可行的。 相似文献
89.
90.
Song Gu Yang Gao Xiuyan Ren Jianhong Yu Lijie Duan Guanghui Gao 《Journal of polymer science. Part A, Polymer chemistry》2018,56(22):1505-1512
Hydrophobic association hydrogels were fabricated via micellar copolymerization of acrylamide and hydrophobic monomers lauryl (meth)acrylate (LA or LMA) in an aqueous solution of sodium dodecyl sulfate. The effect of methyl groups of hydrophobic monomers on the crosslinking network structure and mechanical behavior of the gels was investigated on the basis of rubber elastic theory. It was found that the LMA-gel exhibited higher effective crosslink density and elastic modulus. The methyl groups of hydrophobic monomers limited the flexibility of the methacrylate backbone in the association domain, which resulted in the increment of chains constraints. With the increase of stretch rate, the dissipated energy of LMA-gel increased more highly than that of LA-gel. In addition, the methyl group hindered the movement of polymer chains, leading to the lower recovery efficiency of dissipated energy for LMA-gel. In contract, the LA-gel exhibited a rapid response to external force, and possessed better elasticity and self-recovery property. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1505–1512 相似文献