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1.
Giorgio Roma Aldo Ermili Alessandro Balbi Elda Massa Mario Di Braccio 《Journal of heterocyclic chemistry》1981,18(8):1619-1623
The reaction of 3-(dimethylamino)-1-oxo-1H-naphtho[2,1-b]pyran-2-carbaldehyde (Ia) with o-phenylenediamines or N-monosubstituted o-phenylenediamines in refluxing glacial acetic acid afforded the corresponding naphtho[1′,2′:5,6]pyrano[2,3-b][1,5]benzodiazepin-15-(8H)ones V in very good yields. A similar result was achieved when the reaction was carried out in refluxing pyridine, using N-monosubstituted o-phenylenediamine hydrochlorides. The isolation of a significant intermediate as well as the synthesis through a different univocal pathway confirmed the structure of the compounds V. Moreover the reaction of Ia with N-monosubstituted o-phenylenediamines in refluxing pyridine generally afforded only low yields of compounds V, sometimes together with naphtho[1′,2′:5,6]pyrano[2,3-b][1,5]benzodiazepin-15-(13H)ones VII, isomers of V. 相似文献
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Susana Araceli Carrizales Álvarez Anna Ilyina Karla Monzerratt Gregorio Jáuregui José Luis Martínez Hernández Brenda Berenice Vazquez Gutiérrez Elda Patricia Segura Ceniceros Alejandro Zugasti Cruz Hened Saade Caballero Raúl Guillermo López Campos 《Applied biochemistry and biotechnology》2014,174(5):1945-1958
Avian influenza viruses preferentially bind to sialic acid alpha-2,3-galactose (N-SA-α-2,3-Gal) receptors on epithelial cells. Herein, we describe a procedure we have developed for isolation of N-SA-α-2,3-Gal receptors from porcine trachea using magnetic nanoparticles (NPs) coated with chitosan (NP-Ch) and functionalized with Maackia amurensis lectin (NP-lectin). Magnetic nanoparticles were coated with chitosan in a one-step co-precipitation, and then M. amurensis lectin was immobilized covalently using glutaraldehyde. Lectin coated nanoparticles were incubated with sialic acid enriched fraction of tracheal homogenate, and N-SA-α-2,3-Gal receptor was extracted under magnetic field in two cycles. The presence of 66.4 kDa protein was determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The interaction of immobilized receptor (NP-Ch-R) with M. amurensis lectin (NP-Ch-R-L) was demonstrated by Fourier transform infrared spectrometry (FTIR) and thermogravimetric analysis (TGA). 相似文献
4.
Francesca Al Francesca Miraglia Alessandro Orticoni Elda Judica Maria Cotelli Paolo Maria Rossini Fabrizio Vecchio 《Entropy (Basel, Switzerland)》2020,22(11)
Human brain, a dynamic complex system, can be studied with different approaches, including linear and nonlinear ones. One of the nonlinear approaches widely used in electroencephalographic (EEG) analyses is the entropy, the measurement of disorder in a system. The present study investigates brain networks applying approximate entropy (ApEn) measure for assessing the hemispheric EEG differences; reproducibility and stability of ApEn data across separate recording sessions were evaluated. Twenty healthy adult volunteers were submitted to eyes-closed resting EEG recordings, for 80 recordings. Significant differences in the occipital region, with higher values of entropy in the left hemisphere than in the right one, show that the hemispheres become active with different intensities according to the performed function. Besides, the present methodology proved to be reproducible and stable, when carried out on relatively brief EEG epochs but also at a 1-week distance in a group of 36 subjects. Nonlinear approaches represent an interesting probe to study the dynamics of brain networks. ApEn technique might provide more insight into the pathophysiological processes underlying age-related brain disconnection as well as for monitoring the impact of pharmacological and rehabilitation treatments. 相似文献
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Kaustubh Joshi Warren Batchelor Khairunnisaa Abd Rasid 《Cellulose (London, England)》2011,18(6):1407-1421
No reliable method exists for measuring the cellulose fiber–fiber shear bond strength in paper. This paper reports a simple
method for measuring the fiber–fiber shear bond strength by weakening the fibers independently of the bonds in a sheet of
paper, using acid vapor, until all the fibers break across the fracture line. The bond strength is then calculated from the
fiber strength, as measured by the zero span test, at the point where the fibers first are weakened such that they all break.
The method was used to calculate the average bond strength of handsheets made out of two different pulps. The first pulp was
a never dried, 60% yield, unbleached radiata pine. The bond strength was 25.0 ± 3.3 MPa. Drying the fibers before reslushing
and making sheets reduced the bond strength by up to 33%, with the reduction depending on the severity of the drying treatment.
The second pulp was a bleached dried softwood kraft and was used to investigate the effect of low consistency refining on
bond strength. The bond strength increased from 13.7 ± 1.0 MPa for the sheets made from the unrefined pulp to 37.0 ± 1.0 MPa,
for the sheets made from the most heavily refined pulp. The bond strength measurements are considerably higher than previous
literature estimates for the shear bond strength. The causes for the discrepancy include stress concentrations in tests of
single fiber–fiber bonds. 相似文献
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The combustion generated soot contamination effect on a single diesel droplet ignition and burning was investigated experimentally for the first time. Diesel droplet flame was used to contaminate the droplet to be investigated prior to ignition. Distinct differences in lifetime and stability of the burning of the neat and contaminated droplet samples were observed in their heating, boiling and disruptive phases. For a soot-contaminated droplet surface, the evaporation rate became weaker as a result of slower mass transfer thus contracted the flame formation. Contrary to the burning rate enhancement of droplet with stable and uniform suspension of particles observed by other researchers, the slightest contamination of soot particles in a fuel droplet surface can significantly reduce the burning rate. Denser agglomeration of soot can form a shell on the droplet surface which blocks the flow of gas escaping through the surface thus distort the droplet even further. At late combustion stage, bubbles are observed to rapture on the surface of the soot-contaminated droplet. Strong ejections of volatile liquid and vapour that would explode shortly after parting from the droplet are observed. It seems that the explosion and burning of ejected mixture have little interactions with the enveloped flame surrounding the primary droplet. Enhanced visualisation of droplet liquid-phase has clearly indicated the cause of declining trend in the burning rate and flame stand-off ratio of soot-contaminated diesel droplet. These insights are of significance for understanding the effect of fuel droplet contamination by combustion generated soot particles. 相似文献
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Lara Bianchi Giovanni Petrillo Egon Rizzato Elda Severi Marco Stenta Cinzia Tavani 《Tetrahedron》2009,65(1):336-757
(1E,3Z)-1-Aryl-4-methanesulfonyl-2-nitro-1,3-butadienes (8), derived from the initial ring-opening of 3-nitrothiophene (5), have been found to undergo a facile base-induced cyclization leading to thiopyran S,S-dioxides (9), thus furnishing a further example of effective ring-enlargement from 5- to 6-membered sulfur heterocycles. Compounds 9 are obtained as single racemic mixtures in satisfactory yields; they still contain a nitrovinylic moiety, which can be exploited for further modifications targeted to new derivatives endowed with either synthetic or pharmacological potentialities e.g., in the field of L-type Ca2+-channel blockers. 相似文献
8.
Frego L Gautschi E Martin L Davidson W 《Rapid communications in mass spectrometry : RCM》2006,20(16):2478-2482
Recently, a hydrogen/deuterium exchange method termed SUPREX (Stability of Unpurified Proteins from Rates of hydrogen/deuterium EXchange), capable of measuring protein/ligand binding constants, which utilizes matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), has been reported. Unlike more conventional approaches, SUPREX is inherently capable of measuring Kd values of tight binding ligands. Here we present a SUPREX-based method, incorporating automation and electrospray ionization (ESI)-MS, to measure Kd values for very potent inhibitors of the kinase PKCtheta. The use of ESI offers an alternative to MALDI, with the advantages of improved mass measurement precision for larger proteins, and amenability to automation. Kd values generated by this method are in good agreement with those generated by a molecular protein kinase assay. 相似文献
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Bianchi L Dell'Erba C Maccagno M Petrillo G Rizzato E Sancassan F Severi E Tavani C 《The Journal of organic chemistry》2005,70(22):8734-8738
[reaction: see text] In prosecution of previous work on the thermal cyclization of 1-aryl-4-methanesulfonyl-2-nitro-3-phenylsulfonyl-1,3-butadienes (7), the 3-unsubstituted derivatives 8, deriving from the initial ring opening of 3-nitrothiophene (2), have been likewise found herein to undergo cyclization, followed by aromatization, in analogous mild experimental conditions, leading to the ring-fused homo- or heteroaromatic nitro derivatives 10. The concerted electrocyclic nature of the process is strongly supported by the outcome of tests based on the variation of the polarity of the solvent or of the electron density on the aryl of 8. Thus, the successful application of the process to the non-phenylsulfonyl-activated 8 significantly widens the scope of a synthetically valuable overall ring-opening/ring-closing procedure from nitrothiophenes. Support to the recently renewed interest in thermal 6pi electrocyclizations as a tool for the construction of the benzene ring is furthermore provided. 相似文献
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Elda Markovic Kim Nguyen Stephen Clarke Kristina Constantopoulos Janis Matisons George P. Simon 《Journal of polymer science. Part A, Polymer chemistry》2013,51(23):5038-5045
A series of polyurethane hybrid networks have been synthesized using octakis(m‐isoprenyl‐α,α′‐dimethylbenzylisocyanato dimethylsiloxy) octasilsesquioxane (Q8M8TMI) as a crosslinking agent. The formation of the urethane linkages within the polyurethane hybrids was confirmed by photoacoustic FTIR spectroscopy. The TGA and DSC studies demonstrated that the incorporation of the POSS crosslinking agents altered the thermal properties of the polyurethanes, and that this was dependent on the length of the polyethylene glycol chain. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5038–5045 相似文献