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71.
David E. Portlock Anil C. Ghosh William E. Schwarzel Richard R. Kurtz Eliahu Boger Haldean C. Dalzell Raj K. Razdan 《Journal of heterocyclic chemistry》1976,13(4):781-788
Novel cyclol derivatives (Table 1, 15, 16 ) similar in structure to the peptide portion of ergocornine were synthesized. Detailed experimental procedures are given for the preparation of the cis- 13a and the unknown trans- 14a cyclol esters. 相似文献
72.
Nufer S Marinopoulos AG Gemming T Elsässer C Kurtz W Köstlmeier S Rühle M 《Physical review letters》2001,86(22):5066-5069
Transmission electron microscopy (TEM) and local density functional theory (LDFT) are combined to analyze the microscopic structure of the rhombohedral twin interface in alpha-Al2O3. LDFT provides interfacial energetics and atomic and electronic structures for three competing models. With high-resolution TEM the atomic structure at the interface is imaged quantitatively along two orthogonal zone axes. Electron energy loss spectroscopy in TEM with nanoscale spatial resolution yields the interfacial electronic structure. Both experiments confirm the theoretically preferred model quantitatively. 相似文献
73.
J.C Kurtz 《Journal of Differential Equations》1983,49(1):105-123
Variational methods are used in a weighted Sobolev space to prove the existence of solutions for a certain class of singular nonlinear ordinary differential equations. 相似文献
74.
The Fermi surface of tetragonally distorted fcc Co films grown on Cu(001) has been investigated with first-principles calculations and compared with an experimental determination using angle-resolved photoemission. The angular distributions for hnu=21-45 eV are dominated by the structure of the final states rather than by the shape of the Fermi surface. Theoretical estimates of the photoemission matrix elements support this observation. This suggests that photoemission can have limitations in mapping Fermi surfaces, especially for materials that exhibit flat, closely spaced valence bands. 相似文献
75.
Thomas G Kurtz 《Journal of Functional Analysis》1976,23(2):135-144
For each t ? 0, let A(t) generate a contraction semigroup on a Banach space L. Suppose the solution of ut = ?A(t)u is given by an evolution operator V?(t, s). Conditions are given under which converges strongly as ? → 0 to a semigroup T(t) generated by the closure of .This result is applied to the following situation: Let B generate a contraction group S(t) and the closure of ?A + B generate a contraction semigroup S?(t). Conditions are given under which converges strongly to a semigroup generated by the closure of . This work was motivated by and generalizes a result of Pinsky and Ellis for the linearized Boltzmann Equation. 相似文献
76.
77.
Early experimental data on void swelling in electron-irradiated materials disagree with the dislocation bias models based on the dislocation-point defect elastic interactions. Later, this became one of the factors that prompted the development of models based on production bias (PBM) as the main driver for swelling, which assumed that the dislocation bias was much lower than that predicted by theoretical analyses of dislocation bias. However, the PBM in its present form fails to account for important and common observations, namely, the indefinite void growth often observed under cascade irradiation and the swelling saturation observed under high-dose irradiation and in void lattices. In this paper, we show that these contradictions can be naturally resolved in the framework of the rate theory that accounts for the radiation-induced vacancy emission from extended defects, such as voids, dislocations and grain boundaries. This modification introduces a new bias type in the theory, namely, the emission bias. This modified rate theory agrees well with the experimental data and demonstrates that the original dislocation bias should be used in rate theory models along with the emission bias in different irradiation environments. The modified theory predictions include, but are not limited to, the radiation-induced annealing of voids, swelling saturation under high-dose irradiation, generally, and in void lattices, in particular. 相似文献
78.
Long TR Faisal S Maity PK Rolfe A Kurtz R Klimberg SV Najjar MR Basha FZ Hanson PR 《Organic letters》2011,13(8):2038-2041
Soluble, high-load ring-opening metathesis polymerization (ROMP)-derived oligomeric triazole phosphates (OTP) are reported for application as efficient triazolating reagents of nucleophilic species. Utilizing a "Click"-capture, ROMP, release protocol, the efficient and purification-free, direct triazolation of N-, O-, and S-nucleophilic species was successfully achieved. A variety of OTP derivatives were rapidly synthesized as free-flowing solids on a multigram scale from commercially available materials. 相似文献
79.
Maity PK Rolfe A Samarakoon TB Faisal S Kurtz RD Long TR Schätz A Flynn DL Grass RN Stark WJ Reiser O Hanson PR 《Organic letters》2011,13(1):8-10
A monomer-on-monomer (MoM) Mitsunobu reaction utilizing norbornenyl-tagged (Nb-tagged) reagents is reported, whereby purification was rapidly achieved by employing ring-opening metathesis polymerization, which was initiated by any of three methods utilizing Grubbs catalyst: (i) free catalyst in solution, (ii) surface-initiated catalyst-armed silica, or (iii) surface-initiated catalyst-armed Co/C magnetic nanoparticles. 相似文献
80.
Minghui Zhu Pengfei Tian Ravi Kurtz Thomas Lunkenbein Jing Xu Robert Schlgl Israel E. Wachs Yi‐Fan Han 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(27):9181-9185
The commercial high‐temperature water‐gas shift (HT‐WGS) catalyst consists of CuO‐Cr2O3‐Fe2O3, where Cu functions as a chemical promoter to increase the catalytic activity, but its promotion mechanism is poorly understood. In this work, a series of iron‐based model catalysts were investigated with in situ or pseudo in situ characterization, steady‐state WGS reaction, and density function theory (DFT) calculations. For the first time, a strong metal‐support interaction (SMSI) between Cu and FeOx was directly observed. During the WGS reaction, a thin FeOx overlayer migrates onto the metallic Cu particles, creating a hybrid surface structure with Cu‐FeOx interfaces. The synergistic interaction between Cu and FeOx not only stabilizes the Cu clusters, but also provides new catalytic active sites that facilitate CO adsorption, H2O dissociation, and WGS reaction. These new fundamental insights can potentially guide the rational design of improved iron‐based HT‐WGS catalysts. 相似文献