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121.
A new ring transformation of 3-halo-2-azidopyridine 1-oxides. A novel synthesis of 1,2-oxazin-6-ones
Rudolph A. Abramovitch Ichiro Shinkai Berkeley W. Cue Francis A. Ragan Jerry L. Atwood 《Journal of heterocyclic chemistry》1976,13(2):415-417
The course of the thermal ring-opening and recyclization of 2-azidopyridine 1-oxides is radically altered by the presence of a 3-halo substituent. Provided the 6-position is blocked, recyclization leads to a 6-cyano-6-halo-1,2-oxazine which hydrolyzes very readily to the 6H-1,2-oxazin-6-one. The structure of 4-bromo-3-methyl-6H-1,2-oxazin-6-one so obtained was confirmed by single crystal X-ray analysis. If the 6-position is not blocked, the product undergoes a further ring opening to give (Z)-β-cyanoacrylates. 相似文献
122.
It was found that the use of conventional Slater type overlap, resonance and kinetic integrals are not compatible with the use of Differential Overlap approximations (DOA). We propose a new set of basis functions, Spherical Orbitals, (SO's) that relieve some of the shortcomings generated by the use of DOA's. The general topology of the SO's is presented along with formulae to be used to solve the inherent integrals. 相似文献
123.
The rotational spectra of αd1- and αd2-ortho-fluorotoluene in the ground state of the methyl group torsion have been measured. The evaluation of the spectra has been based on the theory for the internal rotation of an asymmetric internal top formulated earlier by several authors. The barrier potential being threefold symmetric (V3), each torsional level consists of three nondegenerate substates, designated as sy and ±asy. The sy-state is assigned to the conformation with the unique methyl hydrogen isotope within the molecular heavy-atom plane (sy-rotamer), while the ±asy-states belong to the respective out-of-plane conformation (asy-rotamer). In the torsional ground state the level spacing between the ±asy substates is very small and numerous accidental close degeneracies are present between the rotational level systems based on these torsional substates. The rotational levels involved are strongly perturbed by the coupling between molecular overall rotation and internal rotation. Large deviations from a rigid rotor spectrum and (+) ? (?) intersystem (“tunneling”) transitions are observed. The spectrum of the asy-rotamer can be well reproduced by a “two-dimensional” Hamiltonian containing 11 “rotational constants,” 9 of which are determined by a fit to the spectrum. Several are sufficiently barrier-dependent to derive V3. We obtain (in cal/mole) 567 ± 48 for αd1-ortho-fluorotoluene, 711 ± 40 for the αd2-isotope. The deviations from 649 cal/mole for the normal isotope are appreciable, probably indicating shortcomings of the semirigid model. The sy-rotamer presents a rigid rotor spectrum. 相似文献
124.
Rudolph D Carlsson BG Ragnarsson I Aberg S Andreoiu C Bentley MA Carpenter MP Charity RJ Clark RM Cromaz M Ekman J Fahlander C Fallon P Ideguchi E Macchiavelli AO Mineva MN Reviol W Sarantites DG Seweryniak D Williams SJ 《Physical review letters》2006,96(9):092501
High-spin states in 58Ni have been investigated by means of the fusion-evaporation reaction 28Si(32S, 2p)58Ni at 130 MeV beam energy. Discrete-energy levels are observed in 58Ni at record-breaking 42 MeV excitation energy and angular momenta in excess of 30h. The states form regular rotational bands with unprecedented high rotational frequencies. A comparison with configuration dependent cranked Nilsson-Strutinsky calculations reveals an exceptional two-band crossing scenario, the interaction strength of which is strongly shape dependent. 相似文献
125.
Elhamzaoui H Jousseaume B Toupance T Zakri C Biesemans M Willem R Allouchi H 《Chemical communications (Cambridge, England)》2006,(12):1304-1306
The hydrolysis of a bridged alpha,omega-bis(trialkynylstannylated) compound leads to a hybrid material ordered by self-assembly where the spacer forms two six-membered [1,2]oxastanninane rings by intramolecular coordination. 相似文献
126.
127.
We introduce a scheme for fault tolerantly dealing with losses (or other "leakage" errors) in cluster state computation that can tolerate up to 50% qubit loss. This is achieved passively using an adaptive strategy of measurement--no coherent measurements or coherent correction is required. Since the scheme relies on inferring information about what would have been the outcome of a measurement had one been able to carry it out, we call this counterfactual error correction. 相似文献
128.
The production of pions and protons in the pT range between 10 and 20 GeV/c for Pb+Pb collisions at CERN LHC is studied in the recombination model. It is shown that the dominant mechanism for hadronization is the recombination of shower partons from neighboring jets when the jet density is high. Protons are more copiously produced than pions in that pT range because the coalescing partons can have lower momentum fractions, but no thermal partons are involved. The proton-to-pion ratio can be as high as 20. When such high pT hadrons are used as trigger particles, there will not be any associated particles that are not in the background. 相似文献
129.
Carsten Collon Stephan Eckhardt Joachim Rudolph 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(5):455-469
The modelling of active magnetic bearings based on a network approach is considered. Unlike in the standard modelling approach, where a linearization of the current-force relation for the centred shaft position is used, network models permit to include the position dependence of the bearing force in the force model. This becomes necessary when model based controllers are used to stabilize a magnetically supported shaft in tracking applications. The approach is based on the well known application of network models to magnetic circuits. Further simplifying assumptions are discussed which allow one to obtain a network with a limited number of lumped parameters describing the magnetic behaviour of a magnetic bearing. The modelling of a combined radial and axial bearing serves as an example for the application of the proposed approach. Furthermore, the fitting of the network based model to measured characteristic force curves is discussed. In this context, a method for including saturation effects in the model is sketched. 相似文献
130.
D. Rudolph R. Hoischen M. Hellström S. Pietri Zs. Podolyák P. H. Regan A. B. Garnsworthy S. J. Steer F. Becker P. Bednarczyk L. Cáceres P. Doornenbal J. Gerl M. Górska J. Grebosz I. Kojouharov N. Kurz W. Prokopowicz H. Schaffner H. J. Wollersheim L. -L. Andersson L. Atanasova D. L. Balabanski M. A. Bentley A. Blazhev C. Brandau J. R. Brown C. Fahlander E. K. Johansson A. Jungclaus 《The European Physical Journal A - Hadrons and Nuclei》2008,36(2):131-138
The fragmentation of a 550MeV/u primary beam of 58Ni on a 9Be target has been used to measure time- and energy-correlated γ decays following the implantation of event-by-event discriminated
secondary fragments into a 9Be stopper plate. A new isomeric γ decay with T
1/2 = 14(
) ns and E
γ = 646.2(2) keV is observed and attributed to the decay of the yrast 3/2- state in 53
27Co26 . This short-lived isomeric state has been populated by means of nuclear reactions during the stopping process of the secondary
fragments. The experimental findings are discussed in the framework of large-scale spherical shell model calculations in conjunction
with isospin symmetry-breaking residual interactions for the A = 53 , T
z = ±1/2 mirror nuclei 53Co and 53Fe . 相似文献