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321.
Camille Frangville Marius Rutkevičius Alexander P. Richter Prof. Orlin D. Velev Prof. Simeon D. Stoyanov Dr. Vesselin N. Paunov 《Chemphyschem》2012,13(18):4235-4243
We developed a method for the fabrication of novel biodegradable nanoparticles (NPs) from lignin which are apparently non‐toxic for microalgae and yeast. We compare two alternative methods for the synthesis of lignin NPs which result in particles of very different stability upon change of pH. The first method is based on precipitation of low‐sulfonated lignin from an ethylene glycol solution by using diluted acidic aqueous solutions, which yields lignin NPs that are stable over a wide range of pH. The second approach is based on the acidic precipitation of lignin from a high‐pH aqueous solution which produces NPs stable only at low pH. Our study reveals that lignin NPs from the ethylene glycol‐based precipitation contain densely packed lignin domains which explain the stability of the NPs even at high pH. We characterised the properties of the produced lignin NPs and determined their loading capacities with hydrophilic actives. The results suggest that these NPs are highly porous and consist of smaller lignin domains. Tests with microalgae like Chlamydomonas reinhardtii and yeast incubated in lignin NP dispersions indicated that these NPs lack measurable effect on the viability of these microorganisms. Such biodegradable and environmentally compatible NPs can find applications as drug delivery vehicles, stabilisers of cosmetic and pharmaceutical formulations, or in other areas where they may replace more expensive and potentially toxic nanomaterials. 相似文献
322.
Goodfellow JJ Baruah K Yamamoto K Bonomelli C Krishna B Harvey DJ Crispin M Scanlan CN Davis BG 《Journal of the American Chemical Society》2012,134(19):8030-8033
Protein endoglycosidases are useful for biocatalytic alteration of glycans on protein surfaces, but the currently limited selectivity of endoglycosidases has prevented effective manipulation of certain N-linked glycans widely found in nature. Here we reveal that a bacterial endoglycosidase from Streptococcus pyogenes , EndoS, is complementary to other known endoglycosidases (EndoA, EndoH) used for current protein remodeling. It allows processing of complex-type N-linked glycans +/- core fucosylation but does not process oligomannose- or hybrid-type glycans. This biocatalytic activity now addresses previously refractory antibody glycoforms. 相似文献
323.
Two members of a new class of calix[6]azacryptands, namely, calix[6]tampo and calix[6]tamb, have been synthesized through an efficient [1 + 1] macrocyclization reaction--reduction sequence. One of them has been obtained in a remarkably high overall yield from the known X(6)H(3)Me(3). In comparison to all the other calix[6]azacryptands, they possess unique conformational properties since they present a rigidified cone conformation with a partial filling of the cavity by the methoxy groups. In contrast to calix[6]tampo, the fully protonated derivative of calix[6]tamb behaves as a remarkable molecular receptor toward polar neutral guests. NMR studies have shown that the intracavity binding process is governed by a conformational flip of the aromatic walls of the calixarene core. 相似文献
324.
Chevallier C Bugni TS Feng X Harper MK Orendt AM Ireland CM 《The Journal of organic chemistry》2006,71(6):2510-2513
Cytotoxicity-guided fractionation of the crude methanol extract of a marine sponge, Ircinia sp., yielded tedanolide C (1), a new 18-membered macrolide. The structure was solved by interpreting NMR and MS data, and the relative stereochemistry was determined from a combination of homo- and heteronuclear coupling constants in conjunction with molecular modeling. Compound 1 exhibited potent cytotoxicity against HCT-116 cells in vitro. Cell cycle analysis showed that treatment of cells with compound 1 arrested cells in the S-phase. 相似文献
325.
Equations are proposed for transmission cells in the presence of multiple reflections and absorption which generate unwanted
fringes. These influence adversely band intensity measurements. The infrared (IR) spectra generated with these equations are
compared successfully with experimental spectra obtained with BaF2, ZnSe, and Si windows in parallel mount formation having μm range air gaps. Equations are extended for integration of a variable
path length such as in wedge shaped cells that are used to mitigate fringe formations but generate other odd problems such
as path length determination. These equations allow the evaluation of the transmission obtained from boxcar cells whose parallelism
is a little offset. This phenomenon modifies the fringe intensities. The proposed equations were used to calculate the IR
spectra of pure liquid D2O between BaF2 and ZnSe windows with path lengths of around 25 μm and compared with experimental spectra. Since the fit was very good it
indicates that the proposed equations give better optical properties of pure liquids than that presently available. This is
important for liquid used as standards and in particular water used here as reference. 相似文献
326.
327.
Barbosa AV Déchaine RM Vatikiotis-Bateson E Yehia HC 《The Journal of the Acoustical Society of America》2012,131(3):2162-2172
This paper demonstrates an algorithm for computing the instantaneous correlation coefficient between two signals. The algorithm is the computational engine for analyzing the time-varying coordination between signals, which is called correlation map analysis (CMA). Correlation is computed around any pair of points in the two input signals. Thus, coordination can be assessed across a continuous range of temporal offsets and be detected even when changing over time due to temporal fluctuations. The correlation algorithm has two major features: (i) it is structurally similar to a tunable filter, requiring only one parameter to set its cutoff frequency (and sensitivity), (ii) it can be applied either uni-directionally (computing correlation based only on previous samples) or bi-directionally (computing correlation based on both previous and future samples). Computing instantaneous correlation for a range of time offsets between two signals produces a 2D correlation map, in which correlation is characterized as a function of time and temporal offset. Graphic visualization of the correlation map provides rapid assessment of how correspondence patterns progress through time. The utility of the algorithm and of CMA are exemplified using the spatial and temporal coordination of various audible and visible components associated with linguistic performance. 相似文献
328.
The present work analyses the mechanism of W2C/C nanocomposite formation during sonolysis of W(CO)6 in diphenylmethane (DPhM) solutions. Carbon supported WCx nanoparticles attract much interest as an alternative fuel cell electrocatalysts. Sonolysis of neat DPhM under the effect of 20 kHz power ultrasound in argon at 80 °C yields a sonopolymer as a solid product and acetylene, hydrogen, methane, diacetylene and benzene as gaseous products. Diacetylene is formed due to the secondary sonochemical dimerisation of acetylene obtained at the primary stage of DPhM sonolysis. FTIR and μ-Raman studies show that the sonopolymer consists of a mixture of some polymeric partially oxidized aromatic species, and disordered carbon. Sonolysis of W(CO)6 in diphenylmethane solutions follows the first order kinetics. This process yields monodispersed 2-3 nm X-ray amorphous WCx nanoparticles embedded in amorphous sonopolymer. The annealing of air sensitive as-prepared solids in an inert atmosphere at 600 °C causes formation of stable W2C/C nanocomposite with W2C average particle size in the range of 4-7 nm and hexagonal carbon fine particles with the average size of 30-40 nm. Kinetic study revealed that tungsten carbide is formed inside the cavitation bubble due to the reaction of tungsten nanoparticles originated from primary sonolysis of W(CO)6 with acetylene produced as a result of diphenylmethane sonochemical degradation. 相似文献
329.
A Further Approach to 2,6-Dioxatricyclo[3.3.2.03,7]decane A further synthesis of 2,6-dioxatricyclo[3.3.2.03,7]decane ( 10 ) is described by bridging the 9-oxabicyclo[4.2.1]non-7-en-3endo-ol ( 9 ). The latter compound was prepared by ring expansion starting from the known 8-oxabicyclo[3.2.1]oct-6-en-3-on ( 1 ). 相似文献
330.
Camille A. Correia 《Tetrahedron letters》2010,51(8):1172-2064
The oxidative alkylation of benzylic C-H bonds with 1,3-dicarbonyl compounds was developed using oxygen as the terminal oxidant in the presence of catalytic amounts of FeCl2, CuCl and NHPI. 相似文献