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41.
A new approach to on-line oxygen isotope analysis has been developed which utilises existing elemental analyser and mass spectrometry technology to produce a sample of carbon dioxide gas for oxygen isotople analysis. The method relies on on-line high temperature pyrolysis of the sample over a carbon source followed by a rapid, non-contributive partial catalytic oxidation over nickel powder at between 550 and 600 degrees C. Initial results demonstrate both good precision (better than 0.2 per thousand) and accuracy for both cellulose and silver nitrate samples. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
42.
Angela Alberico Teresa Alberico Carlo Sbordone 《Nonlinear Analysis: Theory, Methods & Applications》2012
We give a Sobolev inequality with the weight K(x) belonging to the class A2∩Gn for the function |u|t and the weight K(x)−1 for |∇u|2. The constant in the relevant inequality is seen to depend on the Gn and A2 constants of the weight. 相似文献
43.
Effect of 808 nm Diode Laser on Swimming Behavior,Food Vacuole Formation and Endogenous ATP Production of Paramecium primaurelia (Protozoa)
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Andrea Amaroli Silvia Ravera Steven Parker Isabella Panfoli Alberico Benedicenti Stefano Benedicenti 《Photochemistry and photobiology》2015,91(5):1150-1155
Photobiomodulation (PBM) has been used in clinical practice for more than 40 years. To clarify the mechanisms of action of PBM at cellular and organism levels, we investigated its effect on Paramecium primaurelia (Protozoa) irradiated by an 808 nm infrared diode laser with a flat‐top handpiece (1 W in CW). Our results led to the conclusion that: (1) the 808 nm laser stimulates the P. primaurelia without a thermal effect, (2) the laser effect is demonstrated by an increase in swimming speed and in food vacuole formation, (3) the laser treatment affects endogenous adenosine triphosphate (ATP) production in a positive way, (4) the effects of irradiation dose suggest an optimum exposure time of 50 s (64 J cm?2 of fluence) to stimulate the Paramecium cells; irradiation of 25 s shows no effect or only mild effects and irradiation up to 100 s does not increase the effect observed with 50 s of treatment, (5) the increment of endogenous ATP concentration highlights the positive photobiomodulating effect of the 808 nm laser and the optimal irradiation conditions by the flat‐top handpiece. 相似文献
44.
Cyclometalated Ruthenium Pincer Complexes as Catalysts for the α-Alkylation of Ketones with Alcohols
Patrick Piehl Roberta Amuso Dr. Elisabetta Alberico Dr. Henrik Junge Prof. Dr. Bartolo Gabriele Dr. Helfried Neumann Prof. Dr. Matthias Beller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(27):6050-6055
Ruthenium PNP pincer complexes bearing supplementary cyclometalated C,N-bound ligands have been prepared and fully characterized for the first time. By replacing CO and H− as ancillary ligands in such complexes, additional electronic and steric modifications of this topical class of catalysts are possible. The advantages of the new catalysts are demonstrated in the general α-alkylation of ketones with alcohols following a hydrogen autotransfer protocol. Herein, various aliphatic and benzylic alcohols were applied as green alkylating agents for ketones bearing aromatic, heteroaromatic or aliphatic substituents as well as cyclic ones. Mechanistic investigations revealed that during catalysis, Ru carboxylate complexes are predominantly formed whereas neither the PNP nor the CN ligand are released from the catalyst in significant amounts. 相似文献
45.
The temporal pseudoscalar meson correlation function in a QCD plasma is investigated in a range of temperatures exceeding Tc and yet of experimental interest. Only the flavour-singlet channel is considered and the imaginary time formalism is employed for the finite temperature calculations. The behaviour of the meson spectral function and of the temporal correlator is first studied in the HTL approximation, where one replaces the free thermal quark propagators with the HTL resummed ones. This procedure satisfactory describes the soft fermionic modes, but its application to the propagation of hard quarks is not reliable. An improved version of the so-called NLA scheme, which allows a better treatment of the hard fermionic modes, is then proposed. The impact of the improved NLA on the pseudoscalar temporal correlator is investigated. 相似文献
46.
The strongest possible norms in a priori estimates for solutions to a class of second-order nonlinear elliptic boundary value problems are exhibited. 相似文献
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49.
WM.B. Peatman Gerald B. Kasting David J. Wilson 《Journal of Electron Spectroscopy and Related Phenomena》1975,7(3):233-246
Autoionization electrons in threshold photoionization spectra are known to occur. The effect of such electrons on the interpretation of threshold electron spectra is discussed and a new method is described which enables one to discriminate between zero kinetic energy electrons and energetic electrons in photoionization experiments with little ambiguity. The method largely overcomes the main problem present in some previously described threshold electron studies; namely, the line-of-sight transmission of energetic electrons which gives rise to non-threshold electron peaks. A rejection ratio of 25 is readily obtained for 0.038 eV electrons compared with threshold (zero kinetic energy) electrons and the (small) transition probability for energetic electrons falls off more rapidly than for analysers previously described. Design parameters based on electron trajectory calculations are given for the analyser used, and photoionization results on argon are presented. 相似文献
50.
Richard T Libby Gareth R Howell Iok-Hou Pang Olga V Savinova Adrienne K Mehalow Joseph W Barter Richard S Smith Abbot F Clark Simon WM John 《BMC neuroscience》2007,8(1):108