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81.
J. D. Brockman J. M. Guthrie J. S. Morris J. Davis R. Madsen J. D. Robertson 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(2):405-410
The toenail was examined as a biological monitor of Mg, Zn, and Cu intake using an observational case control model. The One
Source Cohort matched 63 individuals in Columbia Missouri who took the One Source multivitamin with 63 control individuals.
The matching criteria were based on age, sex, ethnicity, smoking status, and body mass index. The multivitamin contained supra-nutritional
levels of Se, Mg, Cu, and Zn. The toenail clippings were examined for these elements using instrumental neutron activation
analysis (INAA). A statistical analysis did not indicate a significant difference for Mg, Cu, or Zn between the nails of One
Source supplement users and control subjects (p<0.76, 0.55, and 0.85, respectively). The trace nutrient Se was used as an internal control. Previous studies have consistently
demonstrated that toenail Se is positively correlated with Se supplement use and the analysis did result in a significant
correlation in the toenails of One Source users and control subjects (p<1·10−4). This internal Se control suggests that the One Source Cohort is largely free from misclassification errors that could interfere
with the biomonitor response for the supranutritional intake of Mg, Cu, and Zn. 相似文献
82.
James A. Madsen Jennifer S. Brodbelt 《Journal of the American Society for Mass Spectrometry》2009,20(3):349-358
The number and types of diagnostic ions obtained by infrared multiphoton dissociation (IRMPD) and collision-induced dissociation
(CID) were evaluated for supercharged peptide ions created by electrospray ionization of solutions spiked with m-nitrobenzyl alcohol. IRMPD of supercharged peptide ions increased the sequence coverage compared with that obtained by CID
for all charge states investigated. The number of diagnostic ions increased with the charge state for IRMPD; however, this
trend was not consistent for CID because the supercharged ions did not always yield the greatest number of diagnostic ions.
Significantly different fragmentation pathways were observed for the different charge states upon CID or IRMPD with the latter
yielding far more immonium ions and often fewer uninformative ammonia, water, and phosphoric acid neutral losses. Pulsed-Q
dissociation resulted in an increase in the number of internal product ions, a decrease in sequence-informative ions, and
reduced overall ion abundances. The enhanced sequence coverage afforded by IRMPD of supercharged ions was demonstrated for
a variety of model peptides, as well as for a tryptic digest of cytochrome c. 相似文献
83.
Madsen GK 《Journal of the American Chemical Society》2006,128(37):12140-12146
An automated band structure calculation based on the inorganic crystal structure database and the augmented plane wave method for electronic structure calculations is presented. Using a rigid band approach and semiclassic Boltzmann theory the band structures are analyzed and a large number of compounds are screened for potential interesting thermoelectric properties. We thereby propose LiZnSb as a potential new thermoelectric material. The k-space structure of the lowest conduction band of LiZnSb is analyzed in detail, and excellent thermoelectric properties are expected for this material. Furthermore the lattice dynamics are calculated, and anisotropic lattice thermal conduction is predicted. 相似文献
84.
N. Zurlo M. Amoretti C. Amsler G. Bonomi C. Carraro C. L. Cesar M. Charlton M. Doser A. Fontana R. Funakoshi P. Genova R. S. Hayano L. V. Jørgensen A. Kellerbauer V. Lagomarsino R. Landua E. Lodi Rizzini M. Macrì N. Madsen G. Manuzio D. Mitchard P. Montagna L. G. Posada H. Pruys C. Regenfus A. Rotondi G. Testera D. P. Van der Werf A. Variola L. Venturelli Y. Yamazaki 《Hyperfine Interactions》2006,172(1-3):97-105
We descrbe how protonium, the quasi-stable antiproton-proton bound system, has been synthesized following the interaction
of antiprotons with the molecular ion in a nested Penning trap environment. From a careful analysis of the spatial distributions of antiproton annihilation events
in the ATHENA experiment, evidence is presented for protonium production with sub-eV kinetic energies in states around n = 70, with low angular momenta. This work provides a new two-body system for studies using laser spectroscopic techniques.
相似文献
85.
86.
Esben P. K. Olsen Prof. Dr. Robert Madsen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(50):16023-16029
A new iridium ‐ catalyzed reaction in which molecular hydrogen and carbon monoxide are cleaved from primary alcohols in the absence of any stoichiometric additives has been developed. The dehydrogenative decarbonylation was achieved with a catalyst generated in situ from [Ir(coe)2Cl]2 (coe=cyclooctene) and racemic 2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl (rac‐BINAP) in a mesitylene solution saturated with water. A catalytic amount of lithium chloride was also added to improve the catalyst turnover. The reaction has been applied to a variety of primary alcohols and gives rise to products in good to excellent yields. Ethers, esters, imides, and aryl halides are stable under the reaction conditions, whereas olefins are partially saturated. The reaction is believed to proceed by two consecutive organometallic transformations that are catalyzed by the same iridium(I)–BINAP species. First, dehydrogenation of the primary alcohol to the corresponding aldehyde takes place, which is then followed by decarbonylation to the product with one less carbon atom. 相似文献
87.
The [Cp*IrCl(2)](2)-catalysed alkylation of amines with alcohols was investigated using a combination of experimental and theoretical methods. A Hammett study involving a series of para-substituted benzyl alcohols resulted in a line with a negative slope. This clearly documents that a positive charge is built up in the transition state, which in combination with the measurement of a significant kinetic isotope effect determines hydride abstraction as being the selectivity-determining step under these conditions. A complementary Hammett study using para-substituted anilines was also carried out. Again, a line with a negative slope was obtained suggesting that nucleophilic attack on the aldehyde is selectivity-determining. A computational investigation of the entire catalytic cycle with full-sized ligands and substrates was performed using density functional theory. The results suggest a catalytic cycle where the intermediate aldehyde stays coordinated to the iridium catalyst and reacts with the amine to give a hemiaminal which is also bound to the catalyst. Dehydration to the imine and reduction to the product amine also takes place without breaking the coordination to the catalyst. The fact that the entire catalytic cycle takes place with all the intermediates bound to the catalyst is important for the further development of this synthetic transformation. 相似文献
88.
89.
L.B. Madsen L.A.A. Nikolopoulos P. Lambropoulos 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(1):67-79
Ab initio time-dependent (TD) calculations of the behavior of positronium (Ps) under strong subpicosecond laser pulses are presented.
The results are compared with results in H through scaling. It is found that a substantial amount of the population can be
found in excited states after the pulse. In the perturbative regime, generalized multiphoton ionization cross-sections are
extracted from the results of the time-dependent calculations. The generalized cross-sections are used to predict the response
of Ps to nanosecond laser pulses at wavelengths of current experimental interest. Beyond the application to Ps, the generality
of the method for extracting generalized cross-sections from TD nonperturbative calculations is discussed.
Received 8 June 1999 相似文献
90.
CM Silva MF Duarte ML Mira MH Florêncio K Versluis AJ Heck 《Rapid communications in mass spectrometry : RCM》1999,13(12):1098-1103
Fast atom bombardment, combined with high-energy collision-induced tandem mass spectrometry, has been used to investigate gas-phase metal-ion interactions with captopril, enalaprilat and lisinopril, all angiotensin-converting enzyme inhibitors.Suggestions for the location of metal-binding sites are presented. For captopril, metal binding occurs most likely at both the sulphur and the nitrogen atom. For enalaprilat and lisinopril, binding preferably occurs at the amine nitrogen. Copyright 1999 John Wiley & Sons, Ltd. 相似文献