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51.
Hafida Harrar‐Ferfera 《应用聚合物科学杂志》2008,107(6):3963-3973
Copolymerizations of methyl methacrylate (MMA) with 4‐vinylpyridine (4VP) were performed from different monomer feed ratios in 1,4‐dioxan at 30°C under free radical initiation experimental conditions, using Ni(II)α‐Benzoinoxime complex as initiator. The obtained copolymers (PMMA4VP) were examined by FTIR and 1H NMR spectroscopies. The composition of these copolymers was calculated, using 1H NMR spectra and elemental analysis. Monomer reactivity ratios were estimated from Fineman–Ross (FR, rm = 0.550, rv = 1.165) and Kelen–Tudos (KT, rm = 0.559, rv = 1.286) linearization methods, as well as nonlinear error in variables model (EVM) method using the RREVM computer program (RREVM, rm = 0.559, rv = 1.264). These values suggest that MMA‐4VP pair copolymerizes randomly. 1H NMR spectra provide information about the stereochemistry of the copolymers in terms of sequence distributions and configurations. These results showed that the age of the Ni complex has an impact not only on its activity towards polymerization reactions but also on the features of the corresponding copolymers, whereas the chemical composition was insensitive to this prominent factor. The mechanism of MMA‐4VP copolymerization is consistent with a radical process as supported by microstructure and molecular weight distribution studies. Thermal behaviours of these copolymers were investigated by differential scanning calorimetry and thermogravimetric analysis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008 相似文献
52.
Preparation of rice husk ash with high specific surface area and chemical reactivity of the product are reported in this paper. The amorphous rice husk ash with high specific surface area of 311 m^2.g^-1 was produced by heating acid treated rice husk at 700~C for 4 h. The isotherms of rice husk ash are similar in shape to type Ⅱ of Brunaner‘s classification with mesopores being predominant. The rice husk ash has a high chemical reactivity, especially that pretreated with acid. This chemical reactivity depends on ashing temperature and pretreatment conditions. There is an exponential relation between the specific surface area of rice husk ash and the change in the conductivity of saturated Ca(OH)2 solution with rice husk ash, from which the specific surface area can be known according to the conductivity change. 相似文献
53.
以尿素为沉淀剂,采用均匀沉积沉淀法制备了Zn(Al)O复合氧化物负载Au催化剂,并用于无碱条件下催化氧化甘油制备1,3-二羟基丙酮(DHA)反应,值得注意的是随着载体中Zn/Al摩尔比的不同,负载Au催化剂的催化活性和产物DHA的选择性呈现明显差距。结合X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电镜(TEM)、CO吸附傅里叶变换红外光谱(CO吸附FTIR)等表征手段,发现载体Zn(Al)O复合氧化物中Zn/Al摩尔比会影响表面氧物种的含量并进一步会影响催化剂的催化活性和选择性。当Zn/Al摩尔比为7∶1、反应温度为80℃、氧气压力为10bar、反应2h时获得最佳的甘油转化率(58.5%)和DHA的选择性(95.3%)。同时,还考察了反应温度、反应时间、反应压力及载体的焙烧温度对催化性能的影响,并发现反应条件对催化剂的催化活性和选择性均有不同程度的影响。此外,以Au/Zn(Al)O-7∶1催化剂为基准考察了催化剂的稳定性,并通过表征手段分析了催化剂失活的主要原因。 相似文献
54.
研究在Ni(naph)2-Al(i-Bu)3-BF3.OEt2(简称Ni-Al-B)体系中添加含磷化合物作为配体对丁二烯聚合反应的影响,探索以磷酸三丁酯(TBP)为第4组分的催化体系中,Al/B、Al/Ni,TBP/Ni物质的量比对聚合活性和聚合产物特性粘数的影响,并用FT-IR等表征聚合物结构。结果表明,控制TBP的适量加入[n(TBP)/n(Ni)〈3.0]对体系催化活性的影响很小,聚合产物的特性粘数较亚磷酸三壬基苯酯(TNPP)的低,TBP的加入对聚合产物的微观结构基本上没有影响,仍能合成高顺式-1,4聚丁二烯(顺式质量分数98.68%)。 相似文献
55.
56.
钴对含硅钢镀锌层的组织和生长动力学的影响 总被引:1,自引:0,他引:1
利用扫描电镜及波谱,研究锌浴中的钴对Q235和Q345钢热浸镀锌层组织及其生长动力学的影响.结果表明:锌浴中含0.075%(质量分数)钴时,能完全抑制Q235镀层组织发生硅反应性;而对于Q345,则需要在锌浴中加入0.3%钴才能部分抑制硅反应性;在锌浴中加入少量的钴后,镀层组织中疏松ζ层转变成与液相直接接触的富钴ζ相和由消耗δ相生成的致密ζ相;致密的ζ相层阻止液相和δ相的直接接触;富钴ζ相可容纳大约0.25% Si,避免在固-液界面产生硅的富集,液相通道消失,从而抑制含硅钢热浸镀锌过程中硅反应性的产生. 相似文献
57.
Manuel Gacitúa Alexander Carreo Rosaly Morales-Guevara Dayn Pez-Hernndez Jorge I. Martínez-Araya Eyleen Araya Marcelo Preite Carolina Otero María Macarena Rivera-Zaldívar Andrs Silva Juan A. Fuentes 《International journal of molecular sciences》2022,23(5)
Searching for adequate and effective compounds displaying antimicrobial activities, especially against Gram-positive bacteria, is an important research area due to the high hospitalization and mortality rates of these bacterial infections in both the human and veterinary fields. In this work, we explored (E)-4-amino-3-((3,5-di-tert-butyl-2-hydroxybenzylidene)amino) benzoic acid (SB-1, harboring an intramolecular hydrogen bond) and (E)-2-((4-nitrobenzilidene)amino)aniline (SB-2), two Schiff bases derivatives. Results demonstrated that SB-1 showed an antibacterial activity determined by the minimal inhibitory concentration (MIC) against Staphylococcus aureus, Enterococcus faecalis, and Bacillus cereus (Gram-positive bacteria involved in human and animal diseases such as skin infections, pneumonia, diarrheal syndrome, and urinary tract infections, among others), which was similar to that shown by the classical antibiotic chloramphenicol. By contrast, this compound showed no effect against Gram-negative bacteria (Klebsiella pneumoniae, Escherichia coli, and Salmonella enterica). Furthermore, we provide a comprehensive physicochemical and theoretical characterization of SB-1 (as well as several analyses for SB-2), including elemental analysis, ESMS, 1H and 13C NMR (assigned by 1D and 2D techniques), DEPT, UV-Vis, FTIR, and cyclic voltammetry. We also performed a computational study through the DFT theory level, including geometry optimization, TD-DFT, NBO, and global and local reactivity analyses. 相似文献
58.
Dmitry Oshchepkov Irina Chadaeva Rimma Kozhemyakina Karina Zolotareva Bato Khandaev Ekaterina Sharypova Petr Ponomarenko Anton Bogomolov Natalya V. Klimova Svetlana Shikhevich Olga Redina Nataliya G. Kolosova Maria Nazarenko Nikolay A. Kolchanov Arcady Markel Mikhail Ponomarenko 《International journal of molecular sciences》2022,23(5)
59.
60.
《International Journal of Hydrogen Energy》2019,44(22):11280-11288
In this work, we study the gasification of pellets produced, after densification, by blending olive mill solid wastes, impregnated or not by olive mill waste water, and pine sawdust under different steam/nitrogen atmospheres. The charcoals necessary for the gasification tests were prepared by pyrolysis using a fixed bed reactor. The gasification technique using steam was chosen in order to produce a hydrogen-enriched syngas. Gasification tests were performed using macro-thermogravimetric equipment. Tests were carried out at different temperatures (750 °C, 800 °C, 820 °C, 850 °C and 900 °C), and at different atmospheres composed by nitrogen and steam at different percentages (10%, 20% and 30%). Results show that the mass variation profiles is similar to the usual lingo-cellulosic gasification process. Moreover, the increase of temperatures or water steam partial pressures affects positively the rate of conversion and the char reactivity by accelerating the gasification process. The increase of the gasification yields demonstrates the promise of using olive mill by-products as alternative biofuels (H2 enriched syngas). 相似文献