共查询到20条相似文献,搜索用时 15 毫秒
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Peng Han Lam Jacky W. Y. Leung Fennie S. M. Poon Tommy W. H. Wu Andrew X. Yu Nai-Teng Tang Ben Zhong 《Journal of Sol-Gel Science and Technology》2001,22(3):205-218
Macroscopically homogeneous and visually transparent fullerene-containing glasses are fabricated from sol-gel mixtures of aminated C60 derivatives and tetraethyl orthosilicate (TEOS) through physical blending and chemical reaction. The aminated fullerenes are synthesized by the amination reactions of C60 with 6-amino-1-hexanol, cyclohexylamine, 2-(2-aminoethoxy)ethanol, and 3-aminopropyltriethoxysilane at 100°C under nitrogen. The amination products are purified by filtration, precipitation, and column chromatography and are isolated in good to excellent yields (32–82%). Characterization by NMR, MS, and TGA analyses reveals that the aminated fullerenes possess molecular structures H
x
C60[NH(CH2)6OH]
x
, H
x
C60(NH-cyclo-C6H11)
x
, H
x
C60[NH(CH2CH2O)2H]
x
, and H
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C60[NH(CH2)3Si(OCH2CH3)3]
x
. All the aminated fullerenes except 2 are completely soluble in aqueous alcoholic solutions of TEOS and can be incorporated into silica gel networks by sol-gel process in the absence or presence of drying-control chemical additives, giving crack-free monoliths of large sizes (up to 60 mm). Electronic absorption spectrum of the fullerene glass continuously red shifts with an increase in the C60 content, suggesting the formation of fullerene nanoclusters in the sol-gel process. The fullerene glasses are thermally and optically stable, resisting continuous attack of strong laser pulses of 532 nm for a prolonged period of time without losing their optical limiting power. 相似文献
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具有生理活性的天然有机化合物 总被引:3,自引:0,他引:3
本文从天然药物、天然农药、生长及生态调节物质、精神依赖药物和全合成等几个方面, 通过评论一些有较大社会意义或学术价值的化合物, 试图透视具有生理活性天然有机化合物这一常盛不衰的热点研究领域的发展脉络, 及对人类生活的意义。 相似文献
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Zikai Feng Monila Nadikudi Krystel L. Woolley Ayman L. Hemasa Sueanne Chear Jason A. Smith Nuri Gueven 《Molecules (Basel, Switzerland)》2021,26(5)
Short-chain quinones (SCQs) have been investigated as potential therapeutic candidates against mitochondrial dysfunction, which was largely thought to be associated with the reversible redox characteristics of their active quinone core. We recently reported a library of SCQs, some of which showed potent cytoprotective activity against the mitochondrial complex I inhibitor rotenone in the human hepatocarcinoma cell line HepG2. To better characterize the cytoprotection of SCQs at a molecular level, a bioactivity profile for 103 SCQs with different compound chemistries was generated that included metabolism related markers, redox activity, expression of cytoprotective proteins and oxidative damage. Of all the tested endpoints, a positive correlation with cytoprotection by SCQs in the presence of rotenone was only observed for the NAD(P)H:quinone oxidoreductase 1 (NQO1)-dependent reduction of SCQs, which also correlated with an acute rescue of ATP levels. The results of this study suggest an unexpected mode of action for SCQs that appears to involve a modification of NQO1-dependent signaling rather than a protective effect by the reduced quinone itself. This finding presents a new selection strategy to identify and develop the most promising compounds towards their clinical use. 相似文献
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生长素自旋标记物的合成及生物活性 总被引:1,自引:0,他引:1
将4-氧-2,2,6,6-四甲基哌啶-1-氧自由基(TMPO)与3种植物生长素拼接在一起,合成了相应的腙,以研究TMPO对生长素活性的影响.所得化合物的结构通过IR、ESR、元素分析或MS加以证实.初步生物活性测定表明,与母体相比不仅对绿豆幼苗的生长促进作用无影响,在一定条件下还增强了促进生长的活性 相似文献
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Kazunori Matsui Takayuki Kaneko Yasunori Yaginuma Masaru Ryu 《Journal of Sol-Gel Science and Technology》1997,9(3):273-277
A spin probe TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxy) was dissolved in a tetraethyl orthosilicate sol-gel reaction
system and measured by electron spin resonance spectroscopy at 295 K. The nitrogen hyperfine coupling constant was from 1.64–1.66
mT in the sol-gel solutions. The values were sensitive to the ethanol-to-water ratio of the solutions. The hyperfine coupling
constant in the xerogels was 1.70 mT, which was almost the same as that in water, indicating that the probe molecules were
trapped in silica pores with water adsorbed on the silica surfaces. The motion of TEMPOL in the xerogels was considerably
slower than in the sol-gel solutions. The local viscosity estimated was from 70–90 cP. The ESR spectra of TEMPOL were altered
during the sol-gel process, indicating that adsorbed water on the silicas surfaces has an important role for trapping organic
molecules in sol-gel glasses. 相似文献
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Kordatos Konstantinos Prato Maurizio Menna Enzo Scorrano Gianfranco Maggini Michele 《Journal of Sol-Gel Science and Technology》2001,22(3):237-244
We report on the synthesis of fullerene derivatives containing a trialkoxysilane moiety that exhibit enhanced solubility in solvents commonly used for sol-gel processing. These derivatives have been successfully embedded in glassy bulk samples and thin films that show very promising optical limiting properties. 相似文献
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糖簇分子和糖树状分子及其生物学活性 总被引:2,自引:0,他引:2
糖簇分子和糖树状分子是近年来发展起来的一类新型糖缀合物,其目的是模拟天然存在的“多元效应”。本文主要综述了目前已知糖簇分子和糖树状分子所具有的生物活性及其潜在的应用领域。 相似文献
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为优化抗倒胺结构。合成了30种化合物,用IR,1HNMR及元素分析确定了结构,并进行了水稻发芽试验及田间试验。 相似文献
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Gallardo J. Galliano P. Moreno R. Durán A. 《Journal of Sol-Gel Science and Technology》2000,19(1-3):107-111
Sol-gel materials have been proposed in last years for clinical applications. In this work, bioactive sol-gel coatings were prepared from suspensions of up to 25% wt. of bioactive glass (CaO·SiO2·P2O5) particles in a hybrid sol obtained from TEOS and MTES. Thick dip-coatings showed in vitro bioactivity after a few days, but glass-particles dissolution promotes a slight reduction in the corrosion resistance. In order to overpass this problem, a two-stage sol-gel coating system that includes a first SiO2 hybrid film, acting as barrier against corrosion, and an external bioactive layer from glass particle suspension is proposed. The obtained samples revealed significant improvement in their electrochemical behaviour, and showed in vitro bioactivity. 相似文献
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Existing sol-gel polymerisation/pyrolysis routes employing two separate boron containing metal alkoxide precursors have been applied to form multi-component silicon oxycarbide glasses based on a borosilicon oxycarbide (B–Si–O–C) system. 29Si, and 11B magic angle spinning nuclear magnetic resonance (MAS-NMR) was used to characterize the atomic structure of the gels, glasses and glass ceramics. Structural changes such as glass formation and crystal nucleation were identified by X-ray diffraction (XRD). Transmission electron microscopy (TEM) provided images of crystal nucleation and growth. 相似文献
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Nogami Masayuki Nagakura Takehito Hayakawa Tomokatsu Kasuga Toshihiro 《Journal of Sol-Gel Science and Technology》2000,19(1-3):253-256
Persistent spectral hole burning was studied in Eu3+ ions-doped Al2O3-SiO2 glass prepared by a sol-gel method. The gel synthesized by the hydrolysis of Si- and Al-alkoxides and EuCl3·6H2O was heated in air and hydrogen gas atmospheres. For the glass heated in air to contain OH bonds, the hole was formed by the photoinduced rearrangement of the OH bonds surrounding the Eu3+ ions, and was thermally refilled and erased above 200 K. On the other hand, the glass heated in hydrogen gas showed the hole spectrum above 200 K. It was found that the hole depth was independent of the temperature and was 7% of the total intensity at room temperature. The proposed mechanism was the electron transfer between the Eu3+ ions and the defect centers formed in glass matrix. 相似文献
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Meriam Ben Abdeljawad Xavier Carette Chiara Argentati Sabata Martino Maurice-Franois Gonon Jrmy Odent Francesco Morena Rosica Mincheva Jean-Marie Raquez 《Molecules (Basel, Switzerland)》2021,26(19)
The present work highlights the crucial role of the interfacial compatibilization on the design of polylactic acid (PLA)/Magnesium (Mg) composites for bone regeneration applications. In this regard, an amphiphilic poly(ethylene oxide-b-L,L-lactide) diblock copolymer with predefined composition was synthesised and used as a new interface to provide physical interactions between the metallic filler and the biopolymer matrix. This strategy allowed (i) overcoming the PLA/Mg interfacial adhesion weakness and (ii) modulating the composite hydrophilicity, bioactivity and biological behaviour. First, a full study of the influence of the copolymer incorporation on the morphological, wettability, thermal, thermo-mechanical and mechanical properties of PLA/Mg was investigated. Subsequently, the bioactivity was assessed during an in vitro degradation in simulated body fluid (SBF). Finally, biological studies with stem cells were carried out. The results showed an increase of the interfacial adhesion by the formation of a new interphase between the hydrophobic PLA matrix and the hydrophilic Mg filler. This interface stabilization was confirmed by a decrease in the damping factor (tanδ) following the copolymer addition. The latter also proves the beneficial effect of the composite hydrophilicity by selective surface localization of the hydrophilic PEO leading to a significant increase in the protein adsorption. Furthermore, hydroxyapatite was formed in bulk after 8 weeks of immersion in the SBF, suggesting that the bioactivity will be noticeably improved by the addition of the diblock copolymer. This ceramic could react as a natural bonding junction between the designed implant and the fractured bone during osteoregeneration. On the other hand, a slight decrease of the composite mechanical performances was noted. 相似文献
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Xanthanolides were particularly characteristic of the genus Xanthium, which exhibited broad biological effects and have drawn much attention in pharmacological application. The review surveyed the structures and bioactivities of the xanthanolides in the genus Xanthium, and summarized the synthesis tactics of xanthanolides. The results indicated that over 30 naturally occurring xanthanolides have been isolated from the genus Xanthium in monomeric, dimeric and trimeric forms. The bioassay-guided fractionation studies suggested that the effective fractions on antitumor activities were mostly from weak polar solvents, and xanthatin (1) was the most effective and well-studied xanthanolide. The varieties of structures and structure-activity relationships of the xanthanolides had provided the promising skeleton for the further study. The review aimed at providing guidance for the efficient preparation and the potential prospects of the xanthanolides in the medicinal industry. 相似文献
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依据活性亚结构的拼接原理,以Baylis-Hillman加成物为原料,设计并合成了5种新的芳基丙烯酸酯类化合物,经IR、1HNMR和元素分析测试技术确证;温室条件下测试了目标化合物的生物活性。结果发现,这些化合物在600ga.i./hm2的剂量下对供试靶标无杀虫活性;在400ga.i./hm2的剂量下对供试靶标无杀菌活性;在2000ga.i./hm2的剂量下,对阔叶杂草百日草(YOA)、苘麻(VEL)和禾本科杂草稗草(BYG)、马唐(CRG)均具有一定的除草活性。这些化合物结构全新,分子中具有多个可供修饰的基团,可作为除草活性的新型先导化合物提供进一步的优化。 相似文献