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161.
We use Padoa's principle of independence of primitive symbols in axiomatic systems in order to discuss the mathematical role of time and spacetime in some classical physical theories. We show that time is eliminable in Newtonian mechanics and that spacetime is also dispensable in Hamiltonian mechanics, Maxwell's electromagnetic theory, the Dirac electron, classical gauge fields, and general relativity. 相似文献
162.
Marleen de Veij Peter Vandenabeele Krystyn Alter Hall Facundo M. Fernandez Michael D. Green Nicholas J. White Arjen M. Dondorp Paul N. Newton Luc Moens 《Journal of Raman spectroscopy : JRS》2007,38(2):181-187
During the last decade there has been an apparent increase in the prevalence of counterfeit medicines in developing as well as developed countries. The pivotal antimalarial artesunate has been counterfeited on a large scale in SE Asia. In this work, the possibilities of Raman spectroscopy are explored as a fast and reliable screening method for the detection of counterfeit artesunate tablets. In this study, 50 ‘artesunate tablets’, purchased in SE Asia, were examined. This spectroscopic method was able to distinguish between genuine and counterfeit artesunate and to identify the composition of the counterfeit tablets. These contained no detectable levels of artesunate, but consisted mostly of starch, calcite (CaCO3), and paracetamol (4‐acetamidophenol). In one particular case an admixture of rutile (TiO2) and artesunate was detected. The results of the investigation by Raman spectroscopy were in agreement with those of colorimetric tests and of liquid chromatography‐mass spectrometry on the artesunate. Moreover, principal components analysis (PCA) was combined with hierarchical cluster analysis to establish an automated approach for the discrimination between different groups of counterfeits and genuine artesunate tablets. These results demonstrate that Raman spectroscopy combined with multivariate analysis is a promising and reliable methodology for the fast characterization of genuine and counterfeit artesunate antimalarial tablets. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
163.
Jenelle Fortunato Jack W. Jordan Graham N. Newton Darren A. Walsh Veronica Augustyn 《Current Opinion in Electrochemistry》2022
The nanoconfinement of electrochemically-active guest species in host solid state electrode materials provides opportunities to tune mass transport between the bulk electrolyte and inner surface of the electrode, enhance electron-transfer rates, and/or improve the stability and dispersion of active material. This review summarizes recent experimental and theoretical electrochemical studies of three types of nanoconfined guest species: (1) ion adsorption of electrolyte ions, (2) confined redox-active molecules, and (3) electrocatalytic reactions of confined ions/solvents and catalytic particles. The examples discussed in this review illustrate how the confinement of guest species within enclosed spaces with nanoscale dimensions – such as pores, pockets, channels, and interlayers – can lead to improved electrochemical performance. 相似文献
164.
M. Cotte M. Auffan W. Degruyter I. Fairchild M. A. Newton G. Morin 《Synchrotron Radiation News》2013,26(5):28-35
In the past two decades, environmental sciences have increased their share in the research portfolios of European synchrotrons, not least for their topicality from a societal point of view. As this field overlaps with many other disciplines, the ESRF decided to establish, in 2005, a dedicated Review Panel for Environmental Science and Cultural Heritage. 相似文献
165.
Dr. Graham N. Newton Dr. Norihisa Hoshino Dr. Takuto Matsumoto Dr. Takuya Shiga Prof. Motohiro Nakano Prof. Hiroyuki Nojiri Prof. Wolfgang Wernsdorfer Prof. Yuji Furukawa Prof. Hiroki Oshio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(40):14205-14212
Here we report the synthesis, structure and detailed characterisation of three n‐membered oxovanadium rings, Nan[(V=O)nNan(H2O)n(α, β, or γ‐CD)2]?m H2O (n=6, 7, or 8), prepared by the reactions of (V=O)SO4?x H2O with α, β, or γ‐cyclodextrins (CDs) and NaOH in water. Their alternating heterometallic vanadium/sodium cyclic core structures were sandwiched between two CD moieties such that O‐Na‐O groups separated the neighbouring vanadyl ions. Antiferromagnetic interactions between the S=1/2 vanadyl ions led to S=0 ground states for the even‐membered rings, but to two quasi‐degenerate S=1/2 states for the spin‐frustrated heptanuclear cluster. 相似文献
166.
167.
It is shown that the estimates, obtained by DoCarmo and Zhou (Trans. Amer. Math. Soc. 351(4):1391–1401, 1999) for the first eigenvalue of the Laplace–Beltrami operator on open manifolds via an oscillation theorem, can be naturally extended to the semi-elliptic singular operator, the p-Laplacian on manifolds, defined by ${\Delta_p(u) := -div (||\nabla u||^{p-2}\nabla u)}$ . 相似文献
168.
Inside Back Cover: Lability‐Controlled Syntheses of Heterometallic Clusters (Angew. Chem. Int. Ed. 11/2014)
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169.
Ana L. Santos Newton C.M. Gomes Isabel Henriques Adelaide Almeida António Correia Angela Cunha 《Photochemistry and photobiology》2013,89(3):640-648
The purpose of this study was to explore the possible link between metals and UV‐B‐induced damage in bacteria. The effect of growth in the presence of enhanced concentrations of different transition metals (Co, Cu, Fe, Mn and Zn) on the UV‐B sensitivity of a set of bacterial isolates was explored in terms of survival, activity and oxidative stress biomarkers (ROS generation, damage to DNA, lipid and proteins and activity of antioxidant enzymes). Metal amendment, particularly Fe, Cu and Mn, enhanced bacterial inactivation during irradiation by up to 35.8%. Amendment with Fe increased ROS generation during irradiation by 1.2–13.3%, DNA damage by 10.8–37.4% and lipid oxidative damage by 9.6–68.7%. Lipid damage during irradiation also increased after incubation with Cu and Co by up to 66.8% and 56.5% respectively. Mn amendment decreased protein carbonylation during irradiation by up to 44.2%. These results suggest a role of Fe, Co, Cu and Mn in UV‐B‐induced bacterial inactivation and the importance of metal homeostasis to limit the detrimental effects of ROS generated during irradiation. 相似文献
170.