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101.
The importance of determining sugars in molasses is emphasized, and a short critical review of the methods available is presented. The difficulties and sources of errors in determining total sugar levels in molasses and sugar mixtures are discussed. A continuous automated procedure based on the hexacyanoferrate(III)/(II) redox reaction has been optimized by reducing the errors and interferences to a minimum. With this technique, sugar concentrations of 0–10 gl-1 can be determined directly. 相似文献
102.
Lodola A Mor M Hermann JC Tarzia G Piomelli D Mulholland AJ 《Chemical communications (Cambridge, England)》2005,(35):4399-4401
Fatty acid amide hydrolase (FAAH), a promising target for the treatment of several central and peripheral nervous system disorders, such as anxiety, pain and hypertension, has an unusual catalytic site, and its mechanism has been uncertain; hybrid quantum mechanics/molecular mechanics (QM/MM) calculations reveal a new mechanism of nucleophile activation (involving a Lys-Ser-Ser catalytic triad), with potentially crucial insights for the design of potent and selective inhibitors. 相似文献
103.
We present novel numerical evidence of spot self-replication controlled by noise in a simple autocatalytic reaction-diffusion system. The system dynamics exhibits a noise controlled transition from stripe growth to spot replication. The growth kinetics is also controlled by noise, and there is an optimal noise intensity for which the multiplication rate of spots is maximal. For larger noise intensities, the spots become unstable and the system is attracted by the trivial steady state. Some of the effects are reminiscent of both polymer chain and cell colony formation in random environments. 相似文献
104.
Meyer JC Paillet M Michel T Moréac A Neumann A Duesberg GS Roth S Sauvajol JL 《Physical review letters》2005,95(21):217401
Using electron diffraction on freestanding single-walled carbon nanotubes, we have determined the structural indices (n,m) of tubes in the diameter range from 1.4 to 3 nm. On the same freestanding tubes, we have recorded Raman spectra of the tangential modes and the radial breathing mode. For the smaller diameters (1.4-1.7 nm), these measurements confirm previously established radial breathing mode frequency versus diameter relations and would be consistent with the theoretically predicted proportionality to the inverse diameter. However, for extending the relation to larger diameters, either a yet unexplained environmental constant has to be assumed, or the linear relation has to be abandoned. 相似文献
105.
Zioutas K Andriamonje S Arsov V Aune S Autiero D Avignone FT Barth K Belov A Beltrán B Bräuninger H Carmona JM Cebrián S Chesi E Collar JI Creswick R Dafni T Davenport M Di Lella L Eleftheriadis C Englhauser J Fanourakis G Farach H Ferrer E Fischer H Franz J Friedrich P Geralis T Giomataris I Gninenko S Goloubev N Hasinoff MD Heinsius FH Hoffmann DH Irastorza IG Jacoby J Kang D Königsmann K Kotthaus R Krcmar M Kousouris K Kuster M Lakić B Lasseur C Liolios A Ljubicić A Lutz G Luzón G Miller DW 《Physical review letters》2005,94(12):121301
Hypothetical axionlike particles with a two-photon interaction would be produced in the sun by the Primakoff process. In a laboratory magnetic field ("axion helioscope"), they would be transformed into x-rays with energies of a few keV. Using a decommissioned Large Hadron Collider test magnet, the CERN Axion Solar Telescope ran for about 6 months during 2003. The first results from the analysis of these data are presented here. No signal above background was observed, implying an upper limit to the axion-photon coupling g(agamma)<1.16x10(-10) GeV-1 at 95% C.L. for m(a) less, similar 0.02 eV. This limit, assumption-free, is comparable to the limit from stellar energy-loss arguments and considerably more restrictive than any previous experiment over a broad range of axion masses. 相似文献
106.
Morán MC Pinazo A Clapés P Infante MR Pons R 《The journal of physical chemistry. B》2005,109(48):22899-22908
Monoacylglycerol amino acid conjugates constitute a novel class of specific biocompatible surfactants that can be considered analogues to partial glycerides and lysophospholipids. They consist of one aliphatic chain and one polar head, i.e., the amino acid, linked through a glycerol moiety. In a previous work, we synthesized monolauroylated amino acid glyceride conjugates, 1-O-lauroyl-rac-glycero-3-O-(N(alpha)-acetyl-L-amino acid), changing the amino acid headgroup systematically: arginine (compound 2), aspartic acid (compound 3), glutamic acid (compound 4), asparagine (compound 5), glutamine (compound 6), and tyrosine (compound 7), to elucidate the structure-properties relationship governing the occurrence of their polymorphism. The thermotropism of the new compounds was measured with polarizing light microscopy, differential scanning calorimetry, and X-ray diffraction and compared with the classical monoglyceride rac-1-lauroylglycerol (compound 1). The experiments were performed for a sequence of heating, cooling, and reheating scans. The results showed that compounds 1-6 exhibit a thermotropic smectic phase. As a consequence, the substitution of the polar head did not engender any curvature into the system, which might lead to the formation of cubic or columnar phases. Interestingly, liquid crystalline phases were not found in the case of compound 7. Small-angle X-ray diffraction data in the gel phase revealed that the substitution of the polar head by the different amino acid structures did not modify significantly the lamellar repeat distance relative to that of the reference one. The observed area per molecule, however, was larger for the new compounds. Consequently, interdigitation was promoted in compounds 2-7. The diffraction patterns were analyzed in terms of electron density profiles, using a modified Caillé theory plus a Gaussian electron density representation (MCG method) on X-ray diffraction data. 相似文献
107.
Moisés Morán 《Transition Metal Chemistry》1981,6(3):173-175
Summary -Cp2Cr reacts with PX3 (X = Cl, Br or I) to give monocyclopentadienylchromium(III) derivatives -CpCrX2 (X = Cl, Br or I), while oxidative additions of IBr and ICl to -Cp2Cr give the corresponding mixed halogenated derivatives, -Cp2CrIX (X = Cl or Br). All products have been characterized by elemental analyses, magnetic moment measurements and by i.r. and e.p.r. spectra. 相似文献
108.
Degrees of Freedom of a Time Series 总被引:4,自引:0,他引:4
We give a formal proof that if f is a smooth dynamics on a d-dimensional smooth manifold and is an ergodic and exact dimensional measure with Hausdorff dimension dim >d–1, then the number d of degrees of freedom of the dynamics can be recovered from the observation of an orbit. We implement, with this purpose, an algorithm based on the analysis of the microstructure of . We show how a correct estimation of d permits the computation of the Liapunov spectrum with a high accuracy avoiding the issue of the spurious exponents. 相似文献
109.
110.
Synthesis of new 3‐alkyl indeno[1,2‐c]pyrazoles, possessing 4‐substituted thiazole moiety at position‐1 derived from 2‐acyl indane‐1,3‐diones, has been described. These compounds and their precursor were screened for their antibacterial (Staphylococcus aureus, Bacillus subtilis, Escherichia coli) and antifungal (Aspergillus niger, Candida albicans) activities. 相似文献