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排序方式: 共有1424条查询结果,搜索用时 184 毫秒
1.
Amano Yuki Ishikawa Satoshi Yoshitake Tatsuhiro Kondou Takahiro 《Nonlinear dynamics》2021,104(3):1917-1935
Nonlinear Dynamics - Rectangular flat-bottom liquid tanks known as tuned liquid dampers (TLDs) are often used as passive mechanical dampers. Sloped- and triangular-bottom TLDs have been reported to... 相似文献
2.
Yuki Shintani Taku Ohtomi Dr. Aya Shibata Dr. Yoshiaki Kitamura Koichiro M. Hirosawa Prof. Kenichi G. N. Suzuki Prof. Masato Ikeda 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(8):e202104421
Aqueous self-assembly of short peptides has attracted growing attention for the construction of supramolecular materials for various bioapplications. Herein, we describe how the thermolysin-assisted biocatalytic construction of a dipeptide hydrazide from an N-protected amino acid and an amino acid hydrazide leads to the formation of thermally stable supramolecular hydrogels. In addition, we demonstrate the post-assembly modification of the supramolecular architectures constructed in situ tethering hydrazide groups as a chemical handle by means of fluorescence imaging. 相似文献
3.
Recently, we developed a convenient microfluidic droplet generation device based on vacuum‐driven fluid manipulation with a piezoelectric diaphragm micropump. In the present study built on our previous work, we investigate the influence of settings applied to the piezoelectric pump, such as peak‐to‐peak drive voltage (Vp‐p) and wave frequency, on droplet generation characteristics. Stepwise adjustments to the drive voltage in ±10‐Vp‐p increments over the range of 200?250 Vp‐p during droplet creation revealed that the droplet generation rate could be reproducibly controlled at a specific drive voltage. The droplet generation rate switched within <0.5 s after the input of a new voltage. Although the droplet generation rate depended on the drive voltage, this setting had almost no influence on droplet size. The frequency over the selected range (50?60 Hz) did not markedly influence the droplet generation rate or droplet size. We show that the current fluid manipulation system can be conveniently used for both droplet generation and for rapid droplet reading, which is required in many microfluidic‐based applications. 相似文献
4.
AbstractIn the enthalpy relaxation of poly(vinyl chloride), a decrease in enthalpy upon the isothermal ageing was measured using the differential scanning calorimetry method as a function of ageing time (tA) and ageing temperature. The range of the ageing temperature was from 56?°C (Tg ? 25?°C) to 72?°C (Tg ? 9?°C) where Tg denotes the glass transition temperature. The limiting value of the decrease in enthalpy was determined by applying a stretched exponential function to the measured enthalpy data. The relaxation function (?) was derived from the measured enthalpy and the construction of a master curve was tried by shifting the ? ? tA curves of the respective ageing temperatures horizontally. Although there was no agreement between the shift factors (aT) and the relaxation times of the ? ? tA curves, the superposition was successfully constructed and the aT values obtained for the poly(vinyl chloride) sample were found to be comparable to those reported for viscoelastic experiments over a broad temperature range above and below Tg carried out for different polymers. The origin of the decrease in enthalpy was briefly discussed in terms of the chain dynamics in the isothermal condition. 相似文献
5.
Prof. Akiharu Satake Yuki Suzuki Motonobu Sugimoto Dr. Yusuke Kuramochi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(3):669-684
Bis(imidazolylporphyrinatozinc) molecules linked through a 1,3-butadiynylene moiety respond to the solvents they are dissolved in to afford exclusively extended (E) or stacked (S) supramolecular polymers. This system is expected to be a solvation/desolvation indicator. However, the principles underlying the solvent-dependent formation of the two types of polymers and the mechanism of the transformation between them are unclear. The formation of the polymers is considered to depend on the two types of complementary coordination bonds that can be formed and the π–π interactions between the porphyrins. In this study, the contributions and solvent dependence of both the coordination bonds and the π–π interactions have been investigated. The results clearly indicate that the coordination bonds are weakly or little solvent-dependent, and that the π–π interactions function effectively only in the inner porphyrins of the S-polymer and are strongly solvent-dependent. Thermodynamic analysis revealed that the formation of the E- or S-polymer in solution is determined by the total energies and the type of solvent used. The transformation of the E- to S-polymer was investigated by gel permeation chromatography. The kinetics of the transformation were also determined. The role of the terminal imidazolylporphyrinatozinc moieties was also investigated: The results indicate that the transformation from the E- to S-polymer occurs by an exchange mechanism between the polymers, induced by attack of terminal free imidazolyl groups on a polymer to zinc porphyrins on other polymers. 相似文献
6.
Mitsuki Yamashita Yuna Kawasumi Yuki Tachibana Dr. Shinnosuke Horiuchi Dr. Koji Yamamoto Prof. Tetsuro Murahashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(5):1212-1216
Although small cyclic- and open-chain unsaturated hydrocarbon anions such as cyclopentadienide and open-chain pentadienide are used as the strongly electron-donating auxiliary ligands for metal complexes, more extended π-conjugated unsaturated hydrocarbon anions have rarely been used in coordination chemistry, despite their potential ability to serve as the multiply bridging π-ligands for metal clusters. This work reports isolation of metal chain clusters bearing the multi-dentate, open-chain extended unsaturated hydrocarbon anion ligands. The extended open-chain π-conjugated polyenyl ligands could effectively stabilize oxidized palladium chains, including an unprecedented [Pd4]4+ chain. 相似文献
7.
Yuki Arakawa Hiroki Kuwahara Masatoshi Tokita Gen-ichi Konishi Hideto Tsuji 《Molecular Crystals and Liquid Crystals》2018,662(1):197-207
ABSTRACTWe present a new fabrication approach to achieve a high birefringence film by means of photopolymerization based on an alkylthio-containing rod-like liquid crystalline molecule exhibiting large temperature dependence of birefringence. We designed a new reactive mesogen having alkylthio linkages (BPM–S). It was found that BPM–S had a larger increment of birefringence with decreasing temperature, relative to commercially available alkoxy analog LC242. This result could be thought to be due to enhanced intermolecular attractive interaction for an alkylthio mesogen implied by the proximity of laterally neighboring molecules and cybotactic nematic tendency based on wide-angle X-ray measurement. The uniaxially-aligned photo-polymerized film for BPM–S showed higher birefringence than that for LC 242. 相似文献
8.
Genki Namba Yuki Mimura Prof. Yoshitane Imai Dr. Ryo Inoue Prof. Yasuhiro Morisaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(65):14871-14877
Optically active X-shaped molecules based on the planar chiral [2.2]paracyclophane building block were prepared, in which di(methoxy)terphenyl units were stacked on the central benzene rings. At 25 °C, anisolyl rings freely rotate in solution, while in the crystal form, they are fixed by intramolecular CH–π interactions, thereby leading to the expression of the axial chirality, i.e., propeller chirality was exhibited by the planar chiral [2.2]paracyclophane moiety. The X-shaped molecule exhibited good circularly polarized luminescence (CPL) profiles with moderate ΦPL and a large glum value in the order of 10−3 at 25 °C, in solution. In contrast, at −120 °C, dual CPL emission with opposite signs was observed. According to the theoretical studies, the rotary motion of the anisolyl units is suppressed in the excited states, and so emission from two isomers could be observed. These results demonstrate that the axial chirality was controlled by the planar chirality, leading ultimately to propeller chirality. 相似文献
9.
Dr. Masashi Hasegawa Chika Hasegawa Yuki Nagaya Prof. Dr. Kazunori Tsubaki Prof. Dr. Yasuhiro Mazaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(59):e202202218
Chiral macrocyclic dimers, trimers, and tetramers composed of paraphenylene and tethered binaphthyl were synthesized, and their molecular structures and chiroptical properties were investigated. X-ray analysis and theoretical calculations revealed that multiple twisted molecular structures – dimers, trimers, and tetramers – adopt figure-of-eight, Möbius triangle, and concave rectangle structures, respectively. These homologues have large ϵ values in their UV-vis absorption spectra because of the π-conjugation of the naphthalene-phenylene-naphthalene frameworks. Owing to the shape-persistent ring structure and tethering with −OCH2CH2O−, high fluorescence quantum yields and a relatively high dissymmetry factor gCPL in circularly polarized luminescence (CPL) spectra were achieved. This results in CPL brightness (BCPL) of over 100, which is greater than that of the conventional organic CPL dye. 相似文献
10.
Yuki Sato Dr. Shin-ichi Kawaguchi Dr. Akihiro Nomoto Prof. Dr. Akiya Ogawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(9):2295-2302
Bis-phosphanated compounds are regarded as the most ubiquitous privileged ligand structures in transition-metal catalysis. The development of highly atom economical reactions is of great importance for their syntheses because less atom economical methods often require complicated purification procedures under inert atmospheres to remove excess starting materials and byproducts. Herein, the photoinduced addition reactions of diphosphane monosulfides bearing PV(S)−PIII single bonds to alkenes is disclosed. These reactions require only equimolar amounts of the diphosphane monosulfide relative to the alkene and facilitate highly selective introduction of two different types of phosphorus-containing groups, such as thiophosphoryl and phosphanyl groups, into a variety of alkenes without any catalyst, base, or additive. 相似文献