نتایج جستجو برای: polycarboxylate ether
تعداد نتایج: 22000 فیلتر نتایج به سال:
The affinity of guanidinium and Cu(II) containing hosts for polycarboxylate guests is studied in water by using UV-visible spectroscopy and isothermal titration calorimetry. By combining a Cu(II) coordination site and a diguanidinium moiety around a single scaffold it is found that the Gibbs free-energy release upon binding is greater than could be expected based on the sum of the free energy r...
The chloride penetration resistance of phosphoaluminate cement (PAC) concrete was investigated in this study. The effects of mixture proportioning parameters, including cement content, water–cement ratio (w/c), and superplasticizer content on chloride ion penetration resistance of PAC concrete were investigated by the rapid chloride migration test (RCM). The result shows that the increase of ce...
Ether lipids are ubiquitous constituents of cellular membranes with no discrete cell biological function assigned yet. Using fluorescent polyene-ether lipids we analyzed their intracellular distribution in living cells by microscopy. Mitochondria and the endoplasmic reticulum accumulated high amounts of ether-phosphatidylcholine and ether-phosphatidylethanolamine. Both lipids were specifically ...
This study concerns the structural change of lignin during auto-catalyzed ethanol-water pulping of aspen by 1H-NMR. The results showed that the linkages of alkyl-aryl ether of lignin, such as the α-ether linkages (α-O-4) and the β-ether linkages (β-O-4), were broken and the alkyl part formed carbenium at the Cα and Cβ of the aliphatic branch. Meanwhile, the aryl part of ether accepted one H and...
this paper investigates hollow and porous alumina nanospheres that were previously synthesized to be used for the dehydration of methanol to dimethyl ether (dme). as hollow nanostructures possess characteristics such as low density and high surface to volume ratio, their catalytic activity between hollow and porous structure is compared. for this purpose, three most important parameters (acidit...
in this research, a semi empirical approach has been suggested for calculating the activation energyof unimolecular thermal decomposition of vinyl ethers yielding saturated products. the calculationprocedure is based on the use of molecular mechanics (mm) methods. these methods which involvethe construction of the transition state for a molecule mainly consider the formation of a “hydrogenbridg...
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A method has been developed for the synthesis of semicrystalline poly(arylene ether ether sulfide) materials by first preparing a soluble, amorphous sulfoxide containing precursor, then rapidly reducing the sulfoxide moiety to sulfide. The sulfoxide polymers are synthesized using conventional nucleophilic aromatic substitution reactions between difluorodiphenyl sulfoxide and diphenols. Reductio...
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