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51.
A. E. Stuchbery H. H. Bolotin C. E. Doran I. Morrison L. D. Wood H. Yamada 《Zeitschrift für Physik A Hadrons and Nuclei》1985,320(4):669-674
The gyromagnetic ratios of the 4 1 + , 6 1 + , and 2 2 + states in186W were measured relative to that of the 2 1 + level by means of the transient field implantation perturbedγ-ray angular distribution technique. The nuclei in the states of interest were Coulomb excited using a beam of 220-MeV63Cu projectiles and recoiled swiftly through a thin, polarized Fe foil. The present measurements yielded ratiosg(4 1 + )/g(2 1 + )=1.04±0.07,g(6 1 + )/g(2 1 + )=1.03 ±0.20 andg(2 2 + )/g(2 1 + )=0.63±0.13. The sizable disparity between the measuredg-factors of the ground- and excited-band is examined within the context of the interacting boson approximation model. 相似文献
52.
John L. Wood 《Hyperfine Interactions》1985,22(1-4):379-384
With the availability of modern isotope separator on-line systems it has become possible to make broad and systematic studies of low-energy low-spin nuclear structure. A vital ingredient in such a program is unique spin-parity assignments to all low-lying levels. A most desirable complement to spin-parity information is detailed spectroscopic information. Obtaining such information far from stability is difficult because of low activity production. Nuclear orientation provides a means for obtaining spin assignments usingsingles measurements. This is less demanding on source intensities than - angular correlation coincidence measurements. Further, nuclear orientation can provide information on magnetic moments and on multipole mixing ratios. A number of structural problems are discussed: the need for unique spin assignments in systematics schemes; the need to distinguish between E2+E0 and M1 transitions; the importance of measuring E2-M1 mixing ratios; and the value of magnetic moment information. Particular emphasis is placed on the desirability of obtaining such information in the neutron-deficient Pt, Au, Hg, Tl, Pb and Bi isotopes, based upon the experimental program at the UNISOR facility.Work supported in part by U.S.Dept. of Energy, Contract No. DE-AS05-80ER10599. 相似文献
53.
Full details are given for a modified Mitsunobu approach to the formation of N-alkylated 1,2,4-dithiazolidine-3,5-diones 2 from a wide range of alcohols 10 with predominantly, inversion of configuration. The resulting products 2 can be regarded as protected isocyanates 6. 相似文献
54.
Four, individually addressable 30 microm diameter, e-beam deposited, gold microelectrodes recessed by 6 microm were suitably spaced on a single substrate to avoid diffusional overlap between each microelectrode. The single substrate device was functionalised with thiolated alpha-, beta-, and gamma-cyclodextrin nanocavities without spacer groups to ensure close proximity of the cavities to the electrode surface. The microelectrodes were assessed in two stages. The e-beam deposited micron sized electrodes were characterized using models for recessed and inlaid microdisk electrodes. Subsequently, each individually addressable, atomically flat, micro-patterned gold electrode with thiolated CD ensembles was treated as a nanoporous electrode assembly. Theoretical and experimental results were compared using cyclic voltammetry. Atomic force microscopy was also used to characterise the modified microelectrodes. Comparisons were made with thiolated CDs deposited on macroelectrodes. This is the first report of the behaviour of immobilized CD nanocavities ensembles on atomically flat gold microelectrodes. 相似文献
55.
Complexes of nicotinic and isonicotinic acids and their deuterated analogues with pyridine, 4-Me pyridine and N Me imidazole have been examined by IR spectroscopy. Strong hydrogen bonding between an O atom of the acid and the N atom of the base with the H atom lying closer to the O atom, is present in all systems. 相似文献
56.
The freezing points, conductivities, and densities of NaI, KI, CsI, Bu4NCl, Bu4NBr, Bu4NI, Et4NBr, and Pr4NBr (where Et = ethyl, Pr = propyl, and Bu =n-butyl) in ethylene carbonate have been measured. Osmotic and activity coefficients were calculated from the results. All of the salts studied are strong electrolytes. The trends in the osmotic coefficients of the alkali metal iodides are NaI>KI>CsI, showing that Na+ is more solvated by ethylene carbonate than Cs+. For the tetraalkylammonium halides, the order of osmotic coefficients are Et4NBrPr4NBrBu4NCl>Bu4NBr>Bu4NI. This is the same order as observed in two other high-dielectric-constant solvents, water andN-methylacetamide. The results indicate that the smaller anions are more solvated than the larger anions in ethylene carbonate in contrast to the usual behavior of dipolar aprotic (basic) solvents, such as dimethyl sulfoxide. 相似文献
57.
An increasing number of hereditary diseases are becoming amenable to diagnosis by analysis of DNA as the responsible genes are located and identified. Gel electrophoresis of DNA fragments plays a central role in the diagnosis of hereditary disease. Electrophoretic separation of differently sized fragments enables the characterization or typing of normal variants which are known to be genetically linked to disease genes. For some diseases it is possible to directly detect mutations by DNA electrophoresis. Deletion mutants may be detected by a restriction fragment of altered size or by a failure to amplify a coding region with the polymerase chain reaction. Carriers of small deletions, involving a few base pairs, may be identified by DNA amplification which produces heteroduplexes that show characteristic, anomalous electrophoretic migration. Mutations that alter restriction sites also alter the sizes of restriction fragments. Common disease mutations that alter a single base pair may be detected using a pair of reactions with normal and mutant oligonucleotides under conditions where a perfect match is necessary for hybridization, amplification or ligation. Alternatively a mismatched oligonucleotide primer may be designed to generate a restriction site with either the normal or mutant allele, following DNA amplification. Finally a number of techniques are available that are useful as screening tools for novel mutations. 相似文献
58.
The apparent molar heat capacities of dilute aqueous solutions of acetic, propanoic and succinic acid and sodium salts of the two monofunctional acids were measured at 300 Kp,2
o
. After subtracting the heat capacity of a point mass, the remaining heat capacity was successfully decomposed into functional group contributions at all temperatures. Together with the results of our previous paper on alcohols and diols the heat capacity contributions of the CH2, CH3, OH, COOH, (COOH)2, and COONa groups are now available and these allow reasonably accurate predictions of the heat capacities of all compounds composed of these groups in this temperature range. 相似文献
59.
Fletcher MT Wood BJ Brereton IM Stok JE De Voss JJ Kitching W 《Journal of the American Chemical Society》2002,124(26):7666-7667
The origins of the oxygen atoms in 1,7-dioxaspiro[5.5]undecane (1) and hydroxyspiroacetal (2) from Bactrocera cacuminata, and in 2,8-dimethyl-1,7-dioxaspiro[5.5]undecane (3) and hydroxyspiroacetal (4) from B. cucumis, have been investigated by incorporation studies from both [(18)O(2)]-dioxygen and [(18)O]-water. Combined GC-MS examination and high-field NMR analysis have demonstrated that all oxygen atoms in 1 and 2 from B. cacuminata are dioxygen derived, but in contrast, the spiroacetals 3 and 4 from B. cucumis incorporate one ring oxygen from water and one ring oxygen (and the hydroxyl oxygen in 4) from [(18)O(2)]-dioxygen. These results reveal not only the generality of monoxygenase mediation of spiroacetal formation in Bactrocera sp., but also an unexpected complexity in their biosynthesis. A general paradigm accommodating these and other observations is presented. 相似文献
60.
Melvyn H. Wood 《Chemical physics》1974,5(3):471-477
The shake-up peaks which are observed to high binding energy of the main photoionization peak in the high energy photoeletron spectra of CO (carbon and oxygen core holes), H2O and NH3 have been interpreted by an extension of the singly excited configuration interaction method used previously in the study of the low-lying excited states of these molecules. The results obtained provide a good interpretation of the experimental spectra of these molecules in terms of many shake-up states. It is concluded that relaxed orbitals and an extensive basis set, including diffuse functions, should be used in the calculations in order to obtain good results. 相似文献