Pyridine attacks : Nucleophilic addition of pyridine derivatives to a doubly linked corrole, which is a stable singlet biradical species, occurs at the bay area with high regioselectivity to provide zwitterionic dimers (see picture; Ar=C6F5). Charge transfer between the anionic corrole and the pyridinium groups induces effective fluorescence quenching of the corrole dimer, which can be utilized for selective fluoride ion recognition.
Divide and conquer : Polymer nanoparticles with phase‐separation structures prepared with block copolymers and homopolymer blends were used to fabricate unique suprapolymer structures by cross‐linking one polymer moiety and dissolving the other (see scheme; PI=polyisoprene, PSt=polystyrene).
In the case of most underground railway stations, no acoustical solutions are used to reduce train noise. Because the reflecting features of train noise in an underground station are not known, appropriate methods for controlling these features have yet to be established. The aim of this study was to clarify the sound field characteristics of underground stations by putting a sound source and receiver on the railway track and platform, respectively. The impulse responses for two vacant underground stations were measured to clarify the effects of the interior materials of the station (Comparison I), and the sound source was put in each station and tunnel to clarify the effect of the noise source positions (Comparison II). Results showed that the sound fields were similar between the stations whose lateral walls were covered with either metallic or fire-resistant wooden panels (Comparison I), and that the sound field for the sound sources near or in the tunnel presented a higher strength (G) by 5.1 dB and longer reverberation time (EDT) by 0.7 s compared to the sound source in the station (Comparison II). The sound sources in the tunnel presented strong and long reverberations at around 500 Hz due to the convergence effect of the tunnel. Therefore, this study proposes a platform screen with doors to limit noise transmission into the platform. 相似文献
Blood levels of the vitamin D3 (D3) metabolites 25-hydroxyvitamin D3 (25(OH)D3), 24R,25-dihydroxyvitamin D3, and 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3) are recognized indicators for the diagnosis of bone metabolism-related diseases, D3 deficiency-related diseases, and hypercalcemia, and are generally measured by liquid-chromatography tandem mass spectrometry (LC-MS/MS) using an isotope dilution method. However, other D3 metabolites, such as 20-hydroxyvitamin D3 and lactone D3, also show interesting biological activities and stable isotope-labeled derivatives are required for LC-MS/MS analysis of their concentrations in serum. Here, we describe a versatile synthesis of deuterium-labeled D3 metabolites using A-ring synthons containing three deuterium atoms. Deuterium-labeled 25(OH)D3 (2), 25(OH)D3-23,26-lactone (6), and 1,25(OH)2D3-23,26-lactone (7) were synthesized, and successfully applied as internal standards for the measurement of these compounds in pooled human serum. This is the first quantification of 1,25(OH)2D3-23,26-lactone (7) in human serum. 相似文献
Post-synthesis modification of polymers streamlines the synthesis of functionalized polymers, but is often incomplete due to the negative polymer effects. Developing efficient polymer reactions in artificial systems thus represents a long-standing objective in the fields of polymer and material science. Here, we show unprecedented macrocycle-metal-complex-catalyzed systems for efficient polymer reaction that result in 100 % transformation of the main chain functional groups presumably via a processive mode reaction. The complete polymer reactions were confirmed in not only intramolecular reaction (hydroamination) but also intermolecular reaction (hydrosilylation) by using Pd- and Pt-macrocycle-catalyzed systems. The most fascinating feature of the both reactions is that higher-molecular-weight polymers reach completion faster. Various studies suggested that the reactions occur in the catalyst cavity via the formation of a supramolecular complex between the macrocycle catalyst and polymer substrate like pseudorotaxane, which should be of characteristic of the efficient polymer reactions progressing in a processive mode. 相似文献
We give necessary and sufficient conditions for the boundedness of generalized fractional integral and maximal operators on Orlicz–Morrey and weak Orlicz–Morrey spaces. To do this, we prove the weak–weak type modular inequality of the Hardy–Littlewood maximal operator with respect to the Young function. Orlicz–Morrey spaces contain spaces (), Orlicz spaces, and generalized Morrey spaces as special cases. Hence, we get necessary and sufficient conditions on these function spaces as corollaries. 相似文献
Porous organic salts (POSs) are constructed through a strong charge-assisted hydrogen bond between sulfonic and amino groups. The molecular design of sulfonic acid, the linker part, enables various porous structures. In the current work, we synthesized p-terphenyl-4,4’’-disulfonic acid (TPDS), whose molecular structure can be easily modified by organic synthesis. Combining of TPDS and bulky tri-p-tolylmethanamine (TPMA-Me), which has three methyl groups at each para-position of the phenyl groups of triphenylmethylamine (TPMA), gave POS with one-dimensional pore channels having two different types of bottlenecks. The central benzene ring of TPDS is exposed on the surface of the pore. Therefore, we combined 4,4′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzenesulfonic acid (BTDBS) containing 2,1,3-benzothiadiazole (BT) with TPMA-Me, and successfully constructed a one-dimensional pore channel with a bottleneck of 3.5 Å, by exposing BT to the surface of the pore. BTDBS/TPMA-Me exhibited a large adsorption/desorption hysteresis of nitrogen because of the bottleneck, electronic state of BT, and larger oxygen adsorption than the isostructural TPDS/TPMA-Me. Systematic and intended modulation of the pore structure of POS based on the modification of sulfonic acid was demonstrated, and for the first time, we established a precise design methodology for a one-dimensional pore channel with a bottleneck and high crystallinity in metal-free porous organic materials. 相似文献
Photocatalytic water splitting is an ideal means of producing hydrogen in a sustainable manner, and developing highly efficient photocatalysts is a vital aspect of realizing this process. The photocatalyst Y2Ti2O5S2 (YTOS) is capable of absorbing at wavelengths up to 650 nm and exhibits outstanding thermal and chemical durability compared with other oxysulfides. However, the photocatalytic performance of YTOS synthesized using the conventional solid-state reaction (SSR) process is limited owing to the large particle sizes and structural defects associated with this synthetic method. Herein, we report the synthesis of YTOS particles by a flux-assisted technique. The enhanced mass transfer efficiency in the flux significantly reduced the preparation time compared with the SSR method. In addition, the resulting YTOS showed improved photocatalytic H2 and O2 evolution activity when loaded with Rh and Co3O4 co-catalysts, respectively. These improvements are attributed to the reduced particle size and enhanced crystallinity of the material as well as the slower decay of photogenerated carriers on a nanosecond to sub-microsecond time range. Further optimization of this flux-assisted method together with suitable surface modification is expected to produce high-quality YTOS crystals with superior photocatalytic activity. 相似文献