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31.
Vandormael B De Wachter R Martins JC Hendrickx PM Keresztes A Ballet S Mallareddy JR Tóth F Tóth G Tourwé D 《ChemMedChem》2011,6(11):2035-2047
Dermorphin analogues, containing a (S)‐ and (R)‐4‐amino‐1,2,4,5‐tetrahydro‐2‐benzazepin‐3‐one scaffold (Aba) and the α‐methylated analogues as conformationally constrained phenylalanines, were prepared. Asymmetric phase‐transfer catalysis was unable to provide the (S)‐α‐Me‐o‐cyanophenylalanine precursor for (S)‐α‐MeAba in acceptable enantiomeric purity. However, by using a Schöllkopf chiral auxiliary, this intermediate was obtained in 88 % ee. [(S)‐Aba 3‐Gly 4]dermorphin retained μ‐opioid affinity but displayed an increased δ‐affinity. The corresponding R epimer was considerably less potent. In contrast, the [(R)‐α‐MeAba 3‐Gly 4]dermorphin isomer was more potent than its S epimer. Tar‐MD simulations of both non‐methylated [Aba 3‐Gly 4]dermorphin analogues showed a degree of folding at the C‐terminal residues toward the N terminus of the peptide, without however, adopting a stabilized β‐turn conformation. The α‐methylated analogues, on the other hand, exhibited a type I/I′ β‐turn conformation over the α‐MeAba 3 and Gly 4 residues, which was stabilized by a hydrogen bond involving Tyr 5‐HN and D ‐Ala 2‐CO. 相似文献
32.
Localized Neuron Stimulation with Organic Electrochemical Transistors on Delaminating Depth Probes
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34.
Min Yan Attila Csík Chun-Chuan Yang Yun Luo Tamás Fodor Shinn-Jyh Ding 《Ceramics International》2018,44(16):19665-19671
Veneering ceramics should be strongly bonded to zirconia core in order to achieve successfully long-term clinical practice. Indeed, to pursue the high zirconia core–veneering ceramic bonding is still a concerned issue. In this regard, this study was to treat zirconia surface using a 3?wt% Si3N4 solution in 4?M NaOH and to investigate the effect of soaking time (5, 10, and 20 days) on the surface properties of zirconia and shear bond strength between zirconia and veneering ceramics. The residual veneering ceramics on zirconia surfaces and failure modes were also examined after fracture. The results showed that the phase composition of zirconia before and after surface modification was not changed. The elemental mapping and depth profiling consistently revealed the soaking-time-dependent Si content on the zirconia surface. The surface roughness of zirconia was significantly (P?<?0.05) increased with the increasing soaking time. When zirconia was treated for 10 days, the shear bond strength value of 27.4?MPa was significantly (P?<?0.05) higher than the control (18.6?MPa), associated with greater remaining amounts of veneering ceramics on the zirconia surface. The failure mode of the treated zirconia was almost the mixed failure. On the basis of the data, surface modification using Si3N4 in NaOH solution for zirconia core could be a simple and effective method for enhancing the veneering ceramic–zirconia bonding. 相似文献
35.
The adhesion of a punch to a linear elastic, confined layer is investigated. Numerical analysis is performed to determine the equivalent elastic modulus in terms of layer confinement. The size of the layer relative to the punch radius and its Poisson’s ratio are found to affect the layer stiffness. The results reveal that the equivalent modulus of a highly confined layer depends on its Poisson’s ratio, whereas, in contrast, an unconfined layer is only sensitive to the extent of the elastic film. The solutions of the equivalent modulus obtained from the simulations are fitted by an analytical function that, subsequently, is utilized to deduce the energy release rate for detachment of the punch via linear elastic fracture mechanics. The energy release rate strongly varies with layer confinement. Regimes for stable and unstable crack growth can be identified that, in turn, are correlated to interfacial stress distributions to distinguish between different detachment mechanisms. 相似文献
36.
Comparison of the group V and VI transition metal carbides for methane dry reforming and thermodynamic prediction of their relative stabilities 总被引:2,自引:0,他引:2
The DME‐SCR activity was suppressed upon exposure of a γ-alumina catalyst to SO2, in contrast to methanol‐SCR, which remains active at the same surface sulphate coverage. This difference in behaviour is attributed to the limited availability of surface methoxy, which may be regarded as a prerequisite for NOx- reduction over γ-alumina under lean conditions, in the case of dimethyl ether in the presence of SO2. This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
37.
The antifungal effects of 22 essential oils from Turkish spices, herbs and citrus peel on four foodborne moulds were evaluated for fungistatic and fungicidal activity. The most active oils were wild thyme (Thymus rariflorus L) and thyme (Thymus serpyllum L). Parsley (Penloselinum sativum Hoffin) and savory (Satureja hortensis L) oils were found to be the least active oils. Rhizopus sp displayed the greatest tolerance, and the most sensitive mould was Penicillium chrysogenum. Prolonged incubations reduced the fungistatic and fungicidal effects of oils. It was concluded that some oils may be useful as mould inhibitors at food additive levels. 相似文献
38.
Reconfiguring flexible machine modules of a PCB assembly line 总被引:2,自引:0,他引:2
Assembly of electronic components to Printed Circuit Boards (PCB) is a complicated manufacturing process and therefore its
control is usually divided into several subtasks which are handled separately. We consider the combined task of determining
a machine configuration and line balancing for a single assembly line of interconnected, reconfigurable machine modules and
one PCB type in production. The modules can be tailored to the needs of each PCB type by suitable assignments for placement
heads, nozzles and feeders. Out of these, the component-to-machine assignment appears to be most difficult and we propose
five different solution methods for it; brute force, random, greedy, local search and genetic algorithm. The genetic algorithm
outperformed the other methods in practical test. 相似文献
39.
We show that deciding if a mixed graph has a well-balanced orientation is NP-complete. 相似文献
40.
Loan Silaghi-Dumitrescu Attila Kun Ionel Haiduc 《Fullerenes, Nanotubes and Carbon Nanostructures》1999,7(5):841-854
AMI molecular orbital calculations with full geometry optimisation of 4/6, 5/5 and 4/5/6 isomers of E20 (E=Si, Ge) show a clear preference of germanium to be accommodated in four membered rings and to achieve coordination numbers greater than 3 (V A). as a consequence, unlike C20 or Si20, the dodecahedral form of Ge20 was not localised on the potential surface, instead an opened structure derived from an octagermaprismane (IV B) can be predicted. Notable kinetic stabilisation in the (SiR)20 systems is suggested by the HOMO-LUMO differences. 相似文献