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121.
Zenghui Yang Fuzhi Song Qihua Wang Tingmei Wang 《Journal of polymer science. Part A, Polymer chemistry》2016,54(24):3858-3867
In this work, two kinds of high temperature shape memory copolyimides were prepared and the shape memory cycles induced structural evolution of macromolecular chains was investigated in detail. The glass transition temperature (Tg) of poly(benzoxazole‐co‐imide) (PI1) and poly(benzimidazole‐co‐imide) (PI2) are 280 °C and 355 °C, respectively. The results show that PI1 could keep stable macromolecular chain structure under shape memory cycles and exhibit outstanding shape memory performance (Rf > 98%, Rr > 97%) under different stretch condition. Whereas, shape memory cycles induced orientation with more ordered macromolecular chains packing is formed for PI2 after several thermal mechanical cycles, which strongly affect physical crosslinking points, thermal mechanical properties as well as shape memory behaviors. The study on macroscopic property and microscopic structure evolution will promote a better understanding of the shape memory effect of polyimides and accelerate development of high performance polyimides for shape memory applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3858–3867 相似文献
122.
Hydrogen peroxide activated by boric acid in the presence of sulfuric acid has been shown to be an efficient oxidizing system for direct conversion of aromatic aldehydes and ketones to phenols. 相似文献
123.
Melanie Schmidlehner Felix Faschinger Lorenz Michael Reith Martin Ertl Wolfgang Schoefberger 《应用有机金属化学》2013,27(7):395-405
In this study, novel water‐soluble corrole amino acid conjugates were synthesized and characterized. The coupling reaction of A2B‐ and A3‐corroles with glycine ethyl ester and taurine under strong basic conditions proved to be successful and yielded di‐ and trifunctionalized corrole amino acid conjugates in good yields. The subsequent metalation of the corrole/amino acid conjugates broadens the scope for applications considerably. As examples, we herein show the catalytic activity of the Mn(III) A3‐corrole towards O2 evolution. First we employed tert‐butyl hydroperoxide (t‐BuOOH) as oxidant to obtain the Mn(V)oxo species and tetrabutyl ammonium hydroxide (TBAH) as hydroxide donor agent. Furthermore, the binding properties of the non‐metalated and the Mn(III) A3‐corrole/amino sulfonic acid conjugates and transport of proteins were investigated and the conjugates exhibited binding to human serum albumin (HSA). Finally, a novel Ga(III) A3‐corrole/amino sulfonic acid derivative was synthesized and we briefly describe the photophysical properties of this compound. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
124.
Afshin Nabiyan Johannes Bernhard Max Dr. Christof Neumann Magdalena Heiland Prof. Dr. Andrey Turchanin Prof. Dr. Carsten Streb Prof. Dr. Felix Helmut Schacher 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(68):16924-16929
An effective strategy to enhance the performance of inorganic semiconductors is moving towards organic-inorganic hybrid materials. Here, we report the design of core–shell hybrid materials based on a TiO2 core functionalized with a polyampholytic (poly(dehydroalanine)-graft-(n-propyl phosphonic acid acrylamide) shell (PDha-g-PAA@TiO2). The PDha-g-PAA shell facilitates the efficient immobilization of the photosensitizer Eosin Y (EY) and enables electronic interactions between EY and the TiO2 core. This resulted in high visible-light-driven H2 generation. The enhanced light-driven catalytic activity is attributed to the unique core–shell design with the graft copolymer acting as bridge and facilitating electron and proton transfer, thereby also preventing the degradation of EY. Further catalytic enhancement of PDha-g-PAA@TiO2 was possible by introducing [Mo3S13]2− cluster anions as hydrogen-evolution cocatalyst. This novel design approach is an example for a multi-component system in which reactivity can in future be independently tuned by selection of the desired molecular or polymeric species. 相似文献
125.
126.
《Optical Fiber Technology》2014,20(6):615-620
We demonstrate a great variability of single-pulse (with only one pulse/wave-packet traveling along the cavity) generation regimes in fiber lasers passively mode-locked by non-linear polarization evolution (NPE) effect. Combining extensive numerical modeling and experimental studies, we identify multiple very distinct lasing regimes with a rich variety of dynamic behavior and a remarkably broad spread of key parameters (by an order of magnitude and more) of the generated pulses. Such a broad range of variability of possible lasing regimes necessitates developing techniques for control/adjustment of such key pulse parameters as duration, radiation spectrum, and the shape of the auto-correlation function. From a practical view point, availability of pulses/wave-packets with such different characteristics from the same laser makes it imperative to develop variability-aware designs with control techniques and methods to select appropriate application-oriented regimes. 相似文献
127.
128.
Impacts of air pressure on the evolution of nanosecond pulse discharge products 总被引:1,自引:0,他引:1
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Based on the nonequilibrium plasma dynamics of air discharge, a dynamic model of zero-dimensional plasma is established by combining the component density equation, the Boltzmann equation, and the energy transfer equation. The evolution properties of nanosecond pulse discharge (NPD) plasma under different air pressures are calculated. The results show that the air pressure has significant impacts on the NPD products and the peak values of particle number density for particles such as O atoms, O3 molecules, N2(A3) molecules in excited states, and NO molecules. It increases at first and then decreases with the increase of air pressure. On the other hand, the peak values of particle number density for N2(B3) and N2(C3) molecules in excited states are only slightly affected by the air pressure. 相似文献
129.
Mandana Amiri Zahra Tofighi Ali Khodayari Abolfazl Bezaatpour Shabnam Sohrabnezhad Vladyslav Mishyn Rabah Boukherroub Sabine Szunerits 《应用有机金属化学》2020,34(10):e5871
We report a Cu-based metal–organic framework (MOF) decorated by CuO nanostructures as an efficient catalyst for the oxygen evolution reaction (OER). MIL-53(Cu) was synthesized by a hydrothermal approach using 1,4-bezenedicarboxylic acid as organic precursor and further annealed at 300°C to form CuO nanostructures on its surface. The produced electrocatalyst, CuO@MIL-53(Cu), was characterized using various techniques. Under alkaline conditions, the developed electrocatalyst exhibited an overpotential of 801 and 336 mV versus RHE at 10 and 1 mA cm−2, respectively. The reproducibility of the catalytic performance was validated using several electrodes. It was confirmed that the CuO hair-like nanostructures grown on MIL-53(Cu) using thermal treatment exhibit high OER activity, good kinetics and durability. CuO@MIL-53(Cu) is an economic noble-metal-free OER electrocatalyst. It has potential for application as anode material for sustainable energy technologies like batteries, fuel cells and water electrolysis. 相似文献
130.
Mengci He Prof. Hongyan Shi Peng Wang Prof. Xiudong Sun Prof. Bo Gao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(70):16106-16113
Molybdenum carbide (Mo2C) is a promising noble-metal-free electrocatalyst for the hydrogen evolution reaction (HER), due to its structural and electronic merits, such as high conductivity, metallic band states and wide pH applicability. Here, a simple CVD process was developed for synthesis of a Mo2C on carbon cloth (Mo2C@CC) electrode with carbon cloth as carbon source and MoO3 as the Mo precursor. XRD, Raman, XPS and SEM results of Mo2C@CC with different amounts of MoO3 and growth temperatures suggested a two-step synthetic mechanism, and porous Mo2C nanostructures were obtained on carbon cloth with 50 mg MoO3 at 850 °C (Mo2C-850(50)). With the merits of unique porous nanostructures, a low overpotential of 72 mV at current density of 10 mA cm−2 and a small Tafel slope of 52.8 mV dec−1 was achieved for Mo2C-850(50) in 1.0 m KOH. The dual role of carbon cloth as electrode and carbon source resulted into intimate adhesion of Mo2C on carbon cloth, offering fast electron transfer at the interface. Cyclic voltammetry measurements for 5000 cycles revealed that Mo2C@CC had excellent electrochemical stability. This work provides a novel strategy for synthesizing Mo2C and other efficient carbide electrocatalysts for HER and other applications, such as supercapacitors and lithium-ion batteries. 相似文献