Abstract The limits of cyclopentadienyl ring-tilting in [l]ferrocenophanes are explored with the incorporation of group 16 elements and a first row element. In this paper the synthesis and ring-opening polymerisation (ROP) behaviour of highly strained chalcogen-and boron- bridged [l]ferrocenophanes will be described. 相似文献
The helicene, pyrido[3,2-f]quinolino[6,5-c]cinnoline 5-oxide, was prepared by treatment of 6-hydroxylaminoquinoline with xanthine oxidase or treatment of 6-nitroquinoline
with glucose in 30% NaOH and the product characterized using NMR, high resolution mass spectrometry, and X-ray crystallography.
The hydrogens on carbons 7 and 12 of the terminal aromatic rings are separated by 2.495 ? creating an angle of 25.0° between
the planes of the two quinoline ring systems. In the crystal, water molecules serve to link the helicenes into a one dimensional
chain structure forming a hydrogen bonded bridge between N2 of one molecule and N4 of another. The molecule (C18H10N4O·H2O) crystallized in the monoclinic P21/n space group. Unit cell parameters for pyrido[3,2-f]quinolino[6,5-c]cinnoline 5-oxide monohydrate: a = 7.0829(12), b = 18.559(3), c = 11.0985(19) ?, β = 107.736(2)°, and Ζ = 4. 相似文献
Setup operations are significant in some production environments. It is mandatory that their production plans consider some features, as setup state conservation across periods through setup carryover and crossover. The modelling of setup crossover allows more flexible decisions and is essential for problems with long setup times. This paper proposes two models for the capacitated lot-sizing problem with backlogging and setup carryover and crossover. The first is in line with other models from the literature, whereas the second considers a disaggregated setup variable, which tracks the starting and completion times of the setup operation. This innovative approach permits a more compact formulation. Computational results show that the proposed models have outperformed other state-of-the-art formulation. 相似文献
Two carbonyl complexes of rhenium, [HRe(CO)5] and [CH3Re(CO)5], were used to probe surface sites of TiO2 (anatase). These complexes were adsorbed from the gas phase onto anatase powder that had been treated in flowing O2 or under vacuum to vary the density of surface OH sites. Infrared (IR) spectra demonstrate the variation in the number of sites, including Ti+3? OH and Ti+4? OH. IR and extended X‐ray absorption fine structure (EXAFS) spectra show that chemisorption of the rhenium complexes led to their decarbonylation, with formation of surface‐bound rhenium tricarbonyls, when [HRe(CO)5] was adsorbed, or rhenium tetracarbonyls, when [CH3Re(CO)5] was adsorbed. These reactions were accompanied by the formation of water and surface carbonates and removal of terminal hydroxyl groups associated with Ti+3 and Ti+4 ions on the anatase. Data characterizing the samples after adsorption of [HRe(CO)5] or [CH3Re(CO)5] determined a ranking of the reactivity of the surface OH sites, with the Ti+3? OH groups being the more reactive towards the rhenium complexes but the less likely to be dehydroxylated. The two rhenium pentacarbonyl probes provided complementary information, suggesting that the carbonate species originate from carbonyl ligands initially bonded to the rhenium and from hydroxyl groups of the titania surface, with the reaction leading to the formation of water and bridging hydroxyl groups on the titania. The results illustrate the value of using a family of organometallic complexes as probes of oxide surface sites. 相似文献
We report results from an experiment on the decay of the high-K isomers in 254No. We have been able to establish the decay from the known high-lying four-quasiparticle isomer, which we assign as a Kπ=16+ state at an excitation energy of Ex=2.928(3) MeV. The decay of this state passes through a rotational band based on a previously unobserved state at Ex=2.012(2) MeV, which we suggest is based on a two-quasineutron configuration with Kπ=10+. This state in turn decays to a rotational band based on the known Kπ=8− isomer, which we infer must also have a two quasineutron configuration. We are able to assign many new gamma-rays associated with the decay of the Kπ=8− isomer, including the identification of a highly K-forbidden ΔK=8 E1 transition to the ground-state band. These results provide valuable new information on the orbitals close to the Fermi surface, pairing correlations, deformation and rotational response, and K-conservation in nuclei of the deformed trans-fermium region. 相似文献
Please release me : The heat generated when metal nanoparticles absorb light results in a significant increase in the temperature of the environment around the particles and is used to selectively break bonds within a molecular system anchored to the nanoparticle surface (see picture). This process represents an advantageous and more universal method to deliver chemicals locally, while avoiding excessive tissue damage.
A motional Stark effect diagnostic has been utilized to reconstruct the parallel current density profile in a spherical-torus plasma for the first time. The measured current profile compares favorably with neoclassical theory when no large-scale magnetohydrodynamic instabilities are present in the plasma. However, a current profile anomaly is observed during saturated interchange-type instability activity. This apparent anomaly can be explained by redistribution of neutral beam injection current drive and represents the first observation of interchange-type instabilities causing such redistribution. The associated current profile modifications contribute to sustaining the central safety factor above unity for over five resistive diffusion times, and similar processes may contribute to improved operational scenarios proposed for ITER. 相似文献