排序方式: 共有22条查询结果,搜索用时 15 毫秒
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Jan F. Rabek Gran Canbck Julia Lucky Bengt Rnby 《Journal of polymer science. Part A, Polymer chemistry》1976,14(6):1447-1462
The photolysis of virgin PVC powder suspended in water, methanol, n-hexane, aqueous NH4OH (30 wt-%), and 0.1 wt-% iodine in methanol and also as dry powder was studied. The mechanism of photolysis of PVC powder has been investigated by using ESR spectroscopy, conductivity titration, gel-permeation chromatography (GPC), and absorption spectroscopy. Photolysis of PVC has been found to occur by a free-radical mechanism. ESR spectroscopy permits a partial identification of several different types of free radicals in PVC such as alkyl, polyenyl, and peroxy radicals. An interpretation is proposed of the mechanism of formation of conjugated polyene structures, and also a new explanation of the crosslinking mechanism, in which transfer of unpaired electrons to double bonds occurs, is suggested. It has also been found that conjugated double bonds can photosensitize free-radical formation as a result of increased ultraviolet absorption due to polyene structures. 相似文献
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Venkataraman Vishwanathan Gajula Balakrishna Balraj Rajesh Venkatreddy Jayasri Lucky Sikhwivhilu Neil J. Coville 《Reaction Kinetics and Catalysis Letters》2007,92(2):311-317
A series of sulphate-promoted ZrO2 solid acid catalysts with different contents of SO4
2− were calcined at 450°C in air for 4 h and tested for the liquid-phase alkylation of catechol to guaiacol in a fixed-bed down-flow
reactor. The 5 wt.% SO4
2− on ZrO2 showed the best conversion (82%) and selectivity for guaiacol (84%) at 200°C and 1 bar pressure. A smooth correlation was
observed between the catalytical activity and surface acidity of sulphated zirconia. Based on our results, a surface mechanism
is proposed. 相似文献
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Quantum dot capped magnetite nanorings as high performance nanoprobe for multiphoton fluorescence and magnetic resonance imaging 总被引:1,自引:0,他引:1
Fan HM Olivo M Shuter B Yi JB Bhuvaneswari R Tan HR Xing GC Ng CT Liu L Lucky SS Bay BH Ding J 《Journal of the American Chemical Society》2010,132(42):14803-14811
In the present study, quantum dot (QD) capped magnetite nanorings (NRs) with a high luminescence and magnetic vortex core have been successfully developed as a new class of magnetic-fluorescent nanoprobe. Through electrostatic interaction, cationic polyethylenimine (PEI) capped QD have been firmly graft into negatively charged magnetite NRs modified with citric acid on the surface. The obtained biocompatible multicolor QD capped magnetite NRs exhibit a much stronger magnetic resonance (MR) T2* effect where the r2* relaxivity and r2*/r1 ratio are 4 times and 110 times respectively larger than those of a commercial superparamagnetic iron oxide. The multiphoton fluorescence imaging and cell uptake of QD capped magnetite NRs are also demonstrated using MGH bladder cancer cells. In particular, these QD capped magnetite NRs can escape from endosomes and be released into the cytoplasm. The obtained results from these exploratory experiments suggest that the cell-penetrating QD capped magnetite NRs could be an excellent dual-modality nanoprobe for intracellular imaging and therapeutic applications. This work has shown great potential of the magnetic vortex core based multifunctional nanoparticle as a high performance nanoprobe for biomedical applications. 相似文献
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阴阳离子菁染料在溴碘化银乳剂颗粒上J-聚体反射光谱 总被引:1,自引:1,他引:0
本文对两种阴阳离子菁染料在碘溴化银立方体颗粒表面的聚集行为进行了研究。用紫外-可见分光光度计测定了菁染料J-聚集的反射光谱曲线。与对应的阴离子、阳离子菁染料各自在碘溴化银立方体颗粒表面的聚集进行了实验对比。结果表明:阴阳离子菁染料吸附在碘溴化银立方体颗料表面形成的J-聚集态的反射光谱具有单个阴离子、阳离子菁染料形成J-聚体反射光谱的峰值波长。表明阴阳离子菁染料具有两个感色区域,既有阴离子菁染料的感色区又有阳离子菁染料的感色区。 相似文献
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James W. Favell Kerry L. Wilkinson Ieva Zigg Sarah M. Lyons Renata Ristic Carolyn J. Puglisi Eric Wilkes Randell Taylor Duane Kelly Greg Howell Marianne McKay Lucky Mokwena Tim Plozza Pei Zhang AnhDuyen Bui Ian Porter Orrin Frederick Jasha Karasek Colleen Szeto Bruce S. Pan Steve Tallman Beth Anne McClure Hui Feng Eric Herv Anita Oberholster Wesley F. Zandberg Matthew Noestheden 《Molecules (Basel, Switzerland)》2022,27(15)
Vineyard exposure to wildfire smoke can taint grapes and wine. To understand the impact of this taint, it is imperative that the analytical methods used are accurate and precise. This study compared the variance across nine commercial and research laboratories following quantitative analysis of the same set of smoke-tainted wines. In parallel, correlations between the interlaboratory consensus values for smoke-taint markers and sensory analyses of the same smoke-tainted wines were evaluated. For free guaiacol, the mean accuracy was 94 ± 11% in model wine, while the free cresols and 4-methylguaiacol showed a negative bias and/or decreased precision relative to guaiacol. Similar trends were observed in smoke-tainted wines, with the cresols and glycosidically bound markers demonstrating high variance. Collectively, the interlaboratory results show that data from a single laboratory can be used quantitatively to understand smoke-taint. Results from different laboratories, however, should not be directly compared due to the high variance between study participants. Correlations between consensus compositional data and sensory evaluations suggest the risk of perceivable smoke-taint can be predicted from free cresol concentrations, overcoming limitations associated with the occurrence of some volatile phenols, guaiacol in particular, as natural constituents of some grape cultivars and of the oak used for barrel maturation. 相似文献
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Lucky RA Medina-Gonzalez Y Charpentier PA 《Langmuir : the ACS journal of surfaces and colloids》2010,26(24):19014-19021
The growth mechanism of one-dimensional metal oxide nanotubular structures is of tremendous current interest to tailor materials using "green" synthetic procedures for emerging industries in alternative energy and biomaterials. In this study, ZrO(2)-modified TiO(2) nanorods and tubular structures were successfully synthesized via a surfactant-free sol-gel route using supercritical carbon dioxide (scCO(2)) as the solvent/drying agent. The effect of metal alkoxide concentration (0.35-1.4 mol/L), acid/metal alkoxide ratio (R = 3-7), and Zr ratio (0-20%) was examined on the morphology and crystallinity of the resulting nanostructures as measured by electron microscopy (SEM and TEM), EDX, XPS, and XRD. The electron microscopy results showed that the crystal growth of the synthesized binary Ti-Zr nanomaterials could be tailored by changing the operating variables with nanotubular structure formed at metal alkoxide concentration of 1.2 mol/L, R = 5-6, and Zr ratio between 4% and 20%. Gelation kinetics for this new system was also studied and revealed that increasing alkoxide concentration and R value enhanced the gelation kinetics. In situ and powder FTIR results revealed that this Ti-Zr binary system follows a similar reaction scheme to that of either single-component system, showing the flexibility of this approach for tailoring nanotubular production. 相似文献
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This communication reports the beneficial effects of co-gasification of biomass and residual oil to produce syngas. In this regard, various blends of glucose (a biomass surrogate) to vacuum gas oil (VGO) have been employed to investigate the synergic effects on the gasification process. The non-isothermal co-gasification experiments were conducted in a thermogravimetric analyzer at different heating rates and gasifying agents. The analysis showed that the co-gasification rate increased with the increase of glucose content in the feedstock. The presence of the oxygen in the biomass molecules helped the overall gasification process. The maximum gasification rate of 42.70 wt/min (DTGmax) was observed with 25 wt% glucose containing sample. The use of gasifying agents appeared to have some influence, especially during high temperature gasification of the glucose-VGO blends. At a same gasification temperature, the co-gasification rate of glucose-VGO blends were found to be 125.7 wt/min and 98.59 wt%/min for N2 and CO2, respectively. The kinetics of the co-gasification of glucose-VGO blends was conducted based on modified random pore model using TGA experimental data and implemented in MATLAB. The estimated activation energy and rate constants were found to be consistent to the observed co-gasification rates. The apparent activation energies of co-gasification of VGO/biomass blends with different weight percentages shows values ranging 60.56–48.25 kJ/mol. The kinetics analysis suggested that the addition of biomass helped to increase the reaction rate by lowering the activation energy required for accomplishing the reactions compared with petroleum carbonaceous feedstocks. The reaction rate constants isotherms are plotted to show that the k-values are exhibiting similar trends at moderate heating rates between 20 and 60 °C/min. This remark arises due to the nature of the reactions involved which are considered to be inherently similar in this range of heating rate. 相似文献