Quantum Windowed Fourier Transform and its Application to Quantum Signal Processing

International Journal of Theoretical Physics - In classical information processing, the windowed Fourier transform (WFT), or short-time Fourier transform, which is a variant of the Fourier...     

Effects of Thieno[3,2-b]thiophene Number on Narrow-Bandgap Fused-Ring Electron Acceptors

Chinese Journal of Polymer Science - We synthesize and compare four near-infrared absorbing fused-ring electron acceptors named as nTTIC (n=2, 3, 4, and 5), based on different number of...     

Passive Advection in a Percolation Process: Two-Loop Approximation

Theoretical and Mathematical Physics - We study an instructive model of the directed percolation process near its second-order phase transition between absorbing and active states. We first express...     

对映-贝壳杉烷型二萜的合成

对映-贝壳衫烷类二萜是陆生植物二萜中种类最为繁多、分子结构和生物活性最为多样的一类天然产物。近年来研究表明,该家族的一些成员具有抗菌和抗肿瘤等活性。这类四环二萜分子可通过分子内环化、氧化断裂和降解重排等方式,转化为复杂的分子骨架。这些天然产物重要的生理活性与多变的骨架结构引起了国内外合成化学家的浓厚兴趣,已经成为全合成研究的又一类热门分子。本文总结了2014年以来国内外学者关于对映-贝壳杉烷型二萜的合成报道,根据这类分子的不同结构类型分别进行阐述。     

Topotactic Conversion of Alkali-Treated Intergrown Germanosilicate CIT-13 into Single-Crystalline ECNU-21 Zeolite as Shape-Selective Catalyst for Ethylene Oxide Hydration

The conversion of the alkali-treated intergrowth germanosilicate CIT-13 into the single-crystalline high-silica ECNU-21 (named after East China Normal University) zeolite, with a novel topology and a highly crystalline zeolite framework, has been realized through a creative top-down strategy involving a mild alkaline-induced multistep process consisting of structural degradation and reconstruction. Instead of acid treatment, hydrolysis in aqueous ammonia solution not only readily cleaved the chemically weak Ge(Si)−O−Ge bonds located within the interlayer double four ring (D4R) units of CIT-13, but also cleaved the metastable Si−O−Si bonds therein. This led to extensive removal of the D4R units, and also generated silanol groups on adjacent silica-rich layers, which then condensed to form a novel daughter structure upon calcination. Individual oxygen bridges in the reassembled ECNU-21 replaced the germanium-rich D4R units in CIT-13, thereby eliminating the original intergrowth phenomenon along the b axis. With an ordered crystalline structure of 10-ring (R) channels as well as suitable germanium-related Lewis acid sites, ECNU-21 serves as a stable solid Lewis acid catalyst for the shape-selective hydration of ethylene oxide (EO) to ethylene glycol (EG) at greatly reduced H₂O/EO ratios and reaction temperature in comparison with the noncatalytic industrial process.     

On the comparison of the Lorentz and Luxemburg norms of the Lp log L space

Analysis Mathematica - The logarithm space Lp log L can be defined by two equivalent, but very differently looking norms. In this note we give estimates for the best constants for the ratio of...     

Synthesis of Pure Silica MWW Zeolite in Fluoride Medium by Using an Imidazolium-Based Long Dication

As the spacer length in 1,2-dimethylimidazolium-based dications increases beyond a specific point (six methylene units), they fail in structure-directing towards STW zeolites in any synthetic conditions. These dications can instead produce, under fluoride concentrated conditions, either *BEA [in the case of the eight-methylene-unit structure-directing agent (SDA)] or MWW (ten methylene units) zeolites. For any length of the dication, the default zeolite (MTW) is a relatively dense zeolite containing a unidimensional channel, whereas the zeolite demanding most specificity (STW, *BEA or MWW) is more porous, affording a larger concentration of the dication to be occluded. This work provides the first reported fluoride synthesis of pure silica MWW zeolites. Charge balance of the organic dications in this zeolite was achieved by combining “structural” silanolates, regular “connectivity defects” and occluded fluoride. Molecular mechanics calculations showed a perfect fit of the decamethylenebis(dimethylimidazolium) dication in the sinusoidal intralayer pore system of MWW. The calculations showed also that the dication is able to stabilize the interlayer space without disturbing the hydrogen-bonding system that holds the layers together in the as-made material. The ¹⁹F magic-angle spinning (MAS) NMR presented two distinct resonances at −71 and −83 ppm, which, on the basis of DFT calculations, we tentatively assigned to fluoride occluded in [4⁶6²] and [4¹5²6²] cages of the MWW structure, respectively. The same DFT study determines a different chemical shift of one methyl ¹³C nuclear magnetic resonance according to the imidazolium ring residing in the sinusoidal channels or in the large cup cavities, thus explaining an experimentally observed splitting of that resonance.     

Monodisperse Six-Armed Starbursts based on Truxene-Cored Multibranched Oligofluorenes: Design,Synthesis, and Stabilized Lasing Characteristics

A series of monodisperse six-armed conjugated starbursts ( Tr1F , Tr2F , and Tr3F ) containing a truxene core and multibranched oligofluorene bridges capped with diphenylamine (DPA) units has been designed, synthesized, and investigated as robust gain media for organic semiconductor lasers (OSLs). The influence of electron-rich DPA end groups on their optoelectronic characteristics has been discussed at length. DPA cappers effectively raise HOMO levels of the starbursts, thus enhancing the hole injection and transport ability. Solution-processed electroluminescence devices based on the resulting six-armed starbursts exhibited efficient deep-blue electroluminescence with clear reduced turn-on voltages (3.2–3.5 V). Moreover, the resulting six-armed molecules showed stabilized electroluminescence and amplified spontaneous emission with low thresholds (27.4–63.9 nJ pulse⁻¹), high net gain coefficients (80.1–101.3 cm⁻¹), and small optical loss (2.6–4.4 cm⁻¹). Distributed feedback OSLs made from Tr3F exhibited a low lasing threshold of 0.31 kW cm⁻² (at 465 nm). The results suggest that the construction of truxene-centered six-armed conjugated starbursts with the incorporation of DPA units can effectively enhance EL properties by precisely regulating the HOMO energy levels, and further optimizing their optical gain properties.