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排序方式: 共有985条查询结果,搜索用时 109 毫秒
981.
Fernandes JP Carvalho BS Luchez CV Politi MJ Brandt CA 《Ultrasonics sonochemistry》2011,18(2):489-493
Allyl 1-naphthyl ethers are useful compounds for different purposes, but reported methods to synthesize them require long reaction times. In this work, we have obtained allyl 1-naphthyl ether in good yield using ultrasonic-assisted methodology in a 1-h reaction. A central composite design was used to obtain a statistical model and a response surface (p<0.05; R(2)=0.970; R(2)(adj)=0.949; R(2)(pred)=0.818) that can predict the optimal conditions to maximize the yield, validated experimentally. 相似文献
982.
Thiago?Caon Betina?Giehl?Zanetti-Ramos Elenara?Lemos-Senna Eric?Cloutet Henri?Cramail Redouane?Borsali Valdir?Soldi Cláudia?Maria?Oliveira?Sim?es 《Journal of nanoparticle research》2010,12(5):1655-1665
The in vitro cytotoxicity and DNA damage evaluation of biodegradable polyurethane-based micro- and nanoparticles were carried
out on animal fibroblasts. For cytotoxicity measurement and primary DNA damage evaluation, MTT and Comet assays were used,
respectively. Different formulations were tested to evaluate the influence of chemical composition and physicochemical characteristics
of particles on cell toxicity. No inhibition of cells growth surrounding the polyurethane particles was observed. On the other
hand, a decrease of cell viability was verified when the anionic surfactant sodium dodecyl sulfate (SDS) was used as droplets
stabilizer of monomeric phase. Polyurethane nanoparticles stabilized with Tween 80 and Pluronic F68 caused minor cytotoxic
effects. These results indicated that the surface charge plays an important role on cytotoxicity. Particles synthesized from
MDI displayed a higher cytotoxicity than those synthesized from IPDI. Size and physicochemical properties of the particles
may explain the higher degree of DNA damage produced by two tested formulations. In this way, a rational choice of particles’
constituents based on their cytotoxicity and genotoxicity could be very useful for conceiving biomaterials to be used as drug
delivering systems. 相似文献
983.
984.
The chemical reduction efficiencies of graphene oxide (GO) are critically important in achieving graphene-like properties in reduced graphene oxide (rGO). In this study, we assessed GO lateral size and its degree of oxidation effect on its chemical reduction efficiency in both suspension and film and the electrical conductivity of the corresponding rGO films. We show that while GO-reduction efficiency increases with the GO size of lower oxidation in suspension, the trend is opposite for film. FESEM, XRD, and Raman analyses reveal that the GO reduction efficiency in film is affected not only by GO size and degree of oxidation but also by its interlayer spacing (restacking) and the efficiency is tunable based on the use of mixed GO. Moreover, we show that the electrical conductivity of rGO films depends linearly on the C/O and Raman ID/IG ratio of rGO and not the lateral size of GO. In this study, an optimal chemical reduction was achieved using premixed large and small GO (L/SGO) at a ratio of 3:1 (w/w). Consequently, the highest electrical conductivity of 85,283 S/m was achieved out of all rGO films reported so far. We hope that our findings may help to pave the way for a simple and scalable method to fabricate tunable, electrically conductive rGO films for electronic applications. 相似文献
985.
Dr. Phillip M. Danby Andrew Jeong Dr. Lyann Sim Dr. Ryan P. Sweeney Jacob F. Wardman Ryan Karimi Dr. Andreas Geissner Dr. Liam J. Worrall Prof. Dr. Jolene. P. Reid Prof. Dr. Natalie C. J. Strynadka Prof. Dr. Stephen G. Withers 《Angewandte Chemie (International ed. in English)》2023,62(21):e202301258
Suitably configured allyl ethers of unsaturated cyclitols act as substrates of β-glycosidases, reacting via allylic cation transition states. Incorporation of halogens at the vinylic position of these carbasugars, along with an activated leaving group, generates potent inactivators of β-glycosidases. Enzymatic turnover of these halogenated cyclitols (F, Cl, Br) displayed a counter-intuitive trend wherein the most electronegative substituents yielded the most labile pseudo-glycosidic linkages. Structures of complexes with the Sulfolobus β-glucosidase revealed similar enzyme-ligand interactions to those seen in complexes with a 2-fluorosugar inhibitor, the lone exception being displacement of tyrosine 322 from the active site by the halogen. Mutation of Y322 to Y322F largely abolished glycosidase activity, consistent with lost interactions at O5, but minimally affected (7-fold) rates of carbasugar hydrolysis, yielding a more selective enzyme for unsaturated cyclitol ether hydrolysis. 相似文献