In this paper, we consider the lattice Schr?dinger equations $$i\dot q_n (t) = \tan \pi (n\alpha + x)q_n (t) + \varepsilon \left( {q_{n + 1} (t) + q_{n - 1} (t)} \right) + \delta v_n (t)\left| {q_n (t)} \right|^{2\tau - 2} q_n (t),$$ with ?? satisfying a certain Diophantine condition, x ?? ?/?, and ?? = 1 or 2, where vn(t) is a spatial localized real bounded potential satisfying |vn(t)| ? Ce???|n|. We prove that the growth of H1 norm of the solution {qn(t)}n??? is at most logarithmic if the initial data {qn(0)}n??? ?? H1 for ? sufficiently small and a.e. x fixed. Furthermore, suppose that the linear equation has a time quasi-periodic potential, i.e., $$i\dot q_n (t) = \tan \pi (n\alpha + x)q_n (t) + \varepsilon \left( {q_{n + 1} (t) + q_{n - 1} (t)} \right) + \delta v_n \left( {\theta ^0 + t\omega } \right)q_n \left( t \right).$$ Then the linear equation can be reduced to an autonomous equation for a.e. x and most values of the frequency vectors ?? if ? and ?? are sufficiently small. 相似文献
Endowing materials with specific functions that are not readily available is always of great importance, but extremely challenging. Co4N, with its beneficial metallic characteristics, has been proved to be highly active for the oxidation of water, while it is notoriously poor for catalyzing the hydrogen evolution reaction (HER), because of its unfavorable d‐band energy level. Herein, we successfully endow Co4N with prominent HER catalytic capability by tailoring the positions of the d‐band center through transition‐metal doping. The V‐doped Co4N nanosheets display an overpotential of 37 mV at 10 mA cm?2, which is substantially better than Co4N and even close to the benchmark Pt/C catalysts. XANES, UPS, and DFT calculations consistently reveal the enhanced performance is attributed to the downshift of the d‐band center, which helps facilitate the H desorption. This concept could provide valuable insights into the design of other catalysts for HER and beyond. 相似文献
Reported herein is the atroposelective synthesis of biaryl NH isoquinolones by RhIII-catalyzed C−H activation of benzamides and intermolecular [4+2] annulation for a broad scope of 2-substituted 1-alkynylnaphthalenes, as well as sterically hindered, symmetric diarylacetylenes. The axial chirality is constructed based on dynamic kinetic transformation of the alkyne in redox-neutral annulation with benzamides, with alkyne insertion being stereodetermining. The reaction accommodates both benzamides and heteroaryl carboxamides and proceeds in excellent regioselectivity (if applicable) and enantioselectivities (average 91.8 % ee). An enantiomerically and diastereomerically pure rhodacyclic complex was prepared and offers insight into enantiomeric control of the coupling system, wherein the steric interactions between the amide directing group and the alkyne substrate dictate both the regio- and enantioselectivity. 相似文献
Vinyl chloride (VC) in the vapor phase of mainstream cigarette smoke was determined under both International Organization for Standardization (ISO) and Health Canada intensive (HCI) machine smoking regimens, which was suspected to be carcinogenic compound. VC was collected by passing the mainstream cigarette smoke through a Cambridge Filter Pad (CFP) into cryogenic traps containing methanol. The impinger solutions were fortified with VC-d3 and analyzed by GC–MS. Limits of detection for vinyl chloride was 0.9 ng mL−1 with the recovery in the range of 93.2–98.4 %. Moreover, the intra-day and inter-day precision was 7.39 and 9.77 %, respectively. Under HCI machine smoking regimen, the vinyl chloride yields in vapor phase of mainstream cigarette smoke were much higher and the average increase was greater than 100 % compared with those under ISO smoking condition.