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排序方式: 共有1946条查询结果,搜索用时 171 毫秒
1.
Dr. Hongying Tang Jian Gao Prof. Yidong Wang Prof. Nanwen Li Dr. Kang Geng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(70):e202202064
Great efforts have been conducted to develop high temperature proton exchange membrane fuel cell (HT-PEMFC) due to its features of enhanced electrocatalyst reactivity, simplified hydrothermal management system and high CO tolerance of catalysts, and remarkable progress has been achieved. However, the easy leaching of phosphoric acid (PA) from the membranes during operation limits its commercial scale-up in complicated environments. This concept here mainly focuses on the recent developments for mitigation of PA loss in PEMs. The probable mechanisms of PA loss are proposed. The approaches to improve PA retention for example via introduction of phosphonic acid by covalent bond, using ion-pairs interaction and siphoning effect, and blending with inorganic nanoparticles are described in detail. Among these strategies, the siphoning effect from the intrinsic microporous PEMs is the most efficient and enables the cell to operate flexibly within a broad temperature range. Therefore, this concept may provide new ideas for the scientists to retain PA, to improve the cell performance and expand the potential applications of PA doped PEMs at elevated humidity and wide temperature range. 相似文献
2.
Daniel Josef Bell Monika Wiese Ariel Augusto Schönberger Matthias Wessling 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(37):16181-16187
Metal–organic frameworks (MOFs) are suitable enzyme immobilization matrices. Reported here is the in situ biomineralization of glucose oxidase (GOD) into MOF crystals (ZIF-8) by interfacial crystallization. This method is effective for the selective coating of porous polyethersulfone microfiltration hollow fibers on the shell side in a straightforward one-step process. MOF layers with a thickness of 8 μm were synthesized, and fluorescence microscopy and a colorimetric protein assay revealed the successful inclusion of GOD into the ZIF-8 layer with an enzyme concentration of 29±3 μg cm−2. Enzymatic activity tests revealed that 50 % of the enzyme activity is preserved. Continuous enzymatic reactions, by the permeation of β-d -glucose through the GOD@ZIF-8 membranes, showed a 50 % increased activity compared to batch experiments, emphasizing the importance of the convective transport of educts and products to and from the enzymatic active centers. 相似文献
3.
Dmytro Strilets Dr. Shixin Fa Arthur Hardiagon Dr. Marc Baaden Prof. Tomoki Ogoshi Dr. Mihail Barboiu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(51):23413-23419
Artificial water channels mimicking natural aquaporins (AQPs) can be used for selective and fast transport of water. Here, we quantify the transport performances of peralkyl-carboxylate-pillar[5]arenes dimers in bilayer membranes. They can transport ≈107 water molecules/channel/second, within one order of magnitude of the transport rates of AQPs, rejecting Na+ and K+ cations. The dimers have a tubular structure, superposing pillar[5]arene pores of 5 Å diameter with twisted carboxy-phenyl pores of 2.8 Å diameter. This biomimetic platform, with variable pore dimensions within the same structure, offers size restriction reminiscent of natural proteins. It allows water molecules to selectively transit and prevents bigger hydrated cations from passing through the 2.8 Å pore. Molecular simulations prove that dimeric or multimeric honeycomb aggregates are stable in the membrane and form water pathways through the bilayer. Over time, a significant shift of the upper vs. lower layer occurs initiating new unexpected water permeation events through toroidal pores. 相似文献
4.
Tongtong Feng Dr. Yingxiang Ye Xiao Liu Hui Cui Dr. Zhiqiang Li Dr. Ying Zhang Dr. Bin Liang Prof. Huanrong Li Prof. Banglin Chen 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(48):21936-21941
Temperature sensors play a significant role in biology, chemistry, and engineering, especially those that can work accurately in a noninvasive manner. We adopted a photoinduced post-synthetic copolymerization strategy to realize a membranous ratiometric luminescent thermometer based on the emissions of two lanthanide ions. This novel mixed-lanthanide polyMOF membrane exhibits not only the integrity and temperature sensing behaviour of the Ln-MOF powder but also excellent mechanical properties, such as flexibility, elasticity, and processability. Moreover, the polyMOF membrane shows remarkable stability under harsh conditions, including high humidity, strong acid and alkali (pH 0–14), which allowed the mapping of temperature distributions in extreme circumstances. This work highlights a simple strategy for polyMOF membrane formation and pushes forward the further practical application of Ln-MOF-based luminescent thermometers in various fields and conditions. 相似文献
5.
Qianqian Gao Dr. Yumeng Zhao Kangli Xu Dr. Chao Zhang Dr. Qian Ma Liqing Qi Dandan Chao Tingting Zheng Linlin Yang Dr. Yanyan Miao Prof. Da Han 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(52):23770-23774
A single-step method for isolation of specific cells based on multiple surface markers will have unique advantages because of its scalability, efficacy, and mildness. Herein, we developed multi-aptamer-mediated proximity ligation method on live cell membranes that leverages a multi-receptor co-recognition design for enhanced specificity, as well as a robust in situ signal amplification design for improved sensitivity of cell isolation. We demonstrated the promising efficacy of our method on differentiating tumor cell subtypes in both cell mixtures and clinical samples. Owing to its simple and fast operation with excellent cell isolation sensitivity and accuracy, this approach will have broad applications in biological science, biomedical engineering, and personalized medicine. 相似文献
6.
Chinomso Nwosu Tara P. Pandey Andrew M. Herring Soenke Seifert E. Bryan Coughlin 《Journal of polymer science. Part A, Polymer chemistry》2020,58(24):3446-3455
Random copolymers of poly(4-vinylpyridine) and polyisoprene were synthesized, and subsequently quaternized with 1-alkylbromides. The number of carbons on the pendant side-chain of the resultant comb-shaped polymer, n, ranged from 2–8. The comb-shaped polymers were crosslinked employing thiol-ene chemistry to give mechanically robust ion conducting membranes. Analysis by wide and medium-angle X-ray scattering show three morphology regimes that are dependent on the number of carbons on the pendant side-chains. When n = 2, ionomer cluster morphology was dominant, when n = 8 backbone-backbone morphology was dominant, and when n = 3–6, the membrane showed a coexistence of both ionomer cluster and backbone-backbone morphologies. Evaluation of the water uptake of the membranes showed a maximum water uptake per cation of 9.5 when n = 5 at 95% relative humidity (RH) and 60°C. Conductivity of the samples characterized by electrochemical impedance spectroscopy showed bromide conductivity as high as 110 mS/cm when n = 3 at 95% RH and 90°C. 相似文献
7.
Synthesis and physical properties of highly branched perfluorinated polymers from AB and AB2 monomers 下载免费PDF全文
Matthew J. Quast Aaron D. Argall Cassandra J. Hager Anja Mueller 《Journal of polymer science. Part A, Polymer chemistry》2015,53(16):1880-1894
Highly branched perfluorinated aromatic polyether copolymers were prepared from the polycondensation of the AB2 monomer, 3,5‐bis[(pentafluorobenzyl)oxy]benzyl alcohol with a variety of fluoroaryl and alkyl bromide AB comonomers. The structures and comonomer distribution of the resulting polymers were characterized in detail. 1H NMR data from kinetic trials illustrated that perfluoroaryl AB comonomer distribution correlated to AB comonomer sterics. 19F NMR data revealed that fluorinated AB monomers and 3‐bromo‐1‐propanol AB monomers were distributed within the AB2 polymer backbone, while longer alkyl bromide AB monomers, 6‐bromo‐1‐hexanol, were mostly distributed along hyperbranched polymer chain ends. In general, as AB comonomer incorporation increased for nonsterically hindered copolymers, thermal decomposition onset increased and glass transition temperatures decreased. The combined data demonstrated the effect of comonomer distribution and sterics on physical properties of AB2‐based polymer systems. The resulting materials were used to cast thin polymer films for measurement of contact angle, which were shown to be directly related to comonomer content. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1880–1894 相似文献
8.
Tobramycin and Nebramine as Pseudo‐oligosaccharide Scaffolds for the Development of Antimicrobial Cationic Amphiphiles 下载免费PDF全文
Yifat Berkov‐Zrihen Ido M. Herzog Raphael I. Benhamou Dr. Mark Feldman Kfir B. Steinbuch Pazit Shaul Dr. Shachar Lerer Dr. Avigdor Eldar Dr. Micha Fridman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(11):4340-4349
Antimicrobial cationic amphiphiles derived from aminoglycoside pseudo‐oligosaccharide antibiotics interfere with the structure and function of bacterial membranes and offer a promising direction for the development of novel antibiotics. Herein, we report the design and synthesis of cationic amphiphiles derived from the pseudo‐trisaccharide aminoglycoside tobramycin and its pseudo‐disaccharide segment nebramine. Antimicrobial activity, membrane selectivity, mode of action, and structure–activity relationships were studied. Several cationic amphiphiles showed marked antimicrobial activity, and one amphiphilic nebramine derivative proved effective against all of the tested strains of bacteria; furthermore, against several of the tested strains, this compound was well over an order of magnitude more potent than the parent antibiotic tobramycin, the membrane‐targeting antimicrobial peptide mixture gramicidin D, and the cationic lipopeptide polymyxin B, which are in clinical use. 相似文献
9.
Using polydimethylsiloxane (PDMS) as a basic matrix to prepare ethanol and butanol permselective pervaporation membranes is a vibrant field. Many studies have verified that the three-dimensional Hansen solubility parameters (HSP) theory offers a valid explanation for the swelling performance of ethanol and butanol in PDMS. Five parameters (δD, δP, δH, δt, and Ra) are defined in HSP theory which can be individually used to explain the interaction strength between a solvent and a polymer. However, for the above five parameters, which one is the most effective parameter for deciding the swelling degree still needs to be determined. In this study, a commonly used hydroxy-terminated PDMS precursor was adopted to prepare the PDMS network. The HSP of the chosen PDMS precursor was measured by an advanced “solubility-rating” method. The special software package HSPiP (4.1.03), purchased from the HSPiP team, was used to process the “solubility-rating” results. The equilibrium swelling degree (Q value) of the PDMS network in water, ethanol, butanol, and toluene was measured and the relationships between the five HSP parameters of the solvents and the logarithmic equilibrium swelling degree, log(Q), were discussed. It was found that the measured polar parameter, δP, of PDMS was 0.12 MPa0.5. The measured hydrogen bonding parameter, δH, was larger than δP, attaining a value of 8.6 MPa0.5, because the hydroxy groups directly contributed to the hydrogen bonding solubility parameter, δH. With respect to the relationships between log(Q) and δD, δP, δH, δt, and Ra, linear relationships existed after plotting log(Q) vs. δP and log(Q) vs. δH. The linear relation degree of the fitted lines was 0.995 and 0.989, respectively. Their standard deviations were 0.149 and 0.232, respectively. Therefore, a better linear relationship existed between log(Q) and δP than the other solubility parameters. This indicated that the polar interaction was the main effect for deciding the swelling degree of the PDMS network in water and alcohol systems. 相似文献
10.
Youping Lin Dr. Lei Wang Prof. Dr. Xin Huang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(72):16440-16450
Compartmentalisation is recognised to be a primary step for the assembly of non-living matter towards the construction of life-like microensembles. To date, a host of hollow microcompartments with various functionalities have been widely developed. Within this respect, given that dynamic behaviour is one of the fundamental features to distinguish living ensembles from those that are non-living, the design and construction of microcompartments with various dynamic behaviours are attracting considerable interest from a wide range of research communities. Significantly, the created dynamic microcompartments could also be widely used as chassis for further bottom-up design towards building protocell models by integrating and booting up necessary biological information. Herein, strategies to install the various motility behaviours into microcompartments, including haptotaxis, chemotaxis and gravitaxis, are summarized in the anticipation of inspiring more designs towards creating various advanced active microcompartments, and contributing new techniques to the ultimate goal of constructing a basic living unit entirely from non-living components. 相似文献