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71.
This work focuses on a new type of cost function based on fractional operators. To do so, the concept of definite integral is extended to arbitrary real-order. Some properties of this new fractional-order definite integral are studied and a fractional-order Barrow's rule is proposed. It is illustrated by an example (the design of an IIR filter) how this new kind of cost function can be a valuable tool in problems where optimal design methods are involved. 相似文献
72.
Dr. Ruth Matesanz Dr. José Fernando Diaz Dr. Francisco Corzana Andrés G. Santana Dr. Agatha Bastida Dr. Juan Luis Asensio 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(10):2875-2889
The most common mode of bacterial resistance to aminoglycoside antibiotics is the enzyme‐catalysed chemical modification of the drug. Over the last two decades, significant efforts in medicinal chemistry have been focused on the design of non‐ inactivable antibiotics. Unfortunately, this strategy has met with limited success on account of the remarkably wide substrate specificity of aminoglycoside‐modifying enzymes. To understand the mechanisms behind substrate promiscuity, we have performed a comprehensive experimental and theoretical analysis of the molecular‐recognition processes that lead to antibiotic inactivation by Staphylococcus aureus nucleotidyltransferase 4′(ANT(4′)), a clinically relevant protein. According to our results, the ability of this enzyme to inactivate structurally diverse polycationic molecules relies on three specific features of the catalytic region. First, the dominant role of electrostatics in aminoglycoside recognition, in combination with the significant extension of the enzyme anionic regions, confers to the protein/antibiotic complex a highly dynamic character. The motion deduced for the bound antibiotic seem to be essential for the enzyme action and probably provide a mechanism to explore alternative drug inactivation modes. Second, the nucleotide recognition is exclusively mediated by the inorganic fragment. In fact, even inorganic triphosphate can be employed as a substrate. Third, ANT(4′) seems to be equipped with a duplicated basic catalyst that is able to promote drug inactivation through different reactive geometries. This particular combination of features explains the enzyme versatility and renders the design of non‐inactivable derivatives a challenging task. 相似文献
73.
Membrane technology is becoming more important for CO 2 separation from natural gas in the new era due to its process simplicity,relative ease of operation and control,compact,and easy to scale up as compared with conventional processes.Conventional processes such as absorption and adsorption for CO 2 separation from natural gas are generally more energy demanding and costly for both operation and maintenance.Polymeric membranes are the current commercial membranes used for CO 2 separation from natural gas.However,polymeric membranes possess drawbacks such as low permeability and selectivity,plasticization at high temperatures,as well as insufficient thermal and chemical stability.The shortcomings of commercial polymeric membranes have motivated researchers to opt for other alternatives,especially inorganic membranes due to their higher thermal stability,good chemical resistance to solvents,high mechanical strength and long lifetime.Surface modifications can be utilized in inorganic membranes to further enhance the selectivity,permeability or catalytic activities of the membrane.This paper is to provide a comprehensive review on gas separation,comparing membrane technology with other conventional methods of recovering CO 2 from natural gas,challenges of current commercial polymeric membranes and inorganic membranes for CO 2 removal and membrane surface modification for improved selectivity. 相似文献
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Dr. Benoît Bertrand Dr. Candice Botuha Jérémy Forté Dr. Héloïse Dossmann Dr. Michèle Salmain 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(56):12846-12861
The two independent and coordination sites of a newly synthesized bis[2-(hydroxyphenyl)-1,2,4-triazole] platform have been exploited to prepare four monometallic neutral ()PtII complexes carrying DMSO, pyridine, triphenylphosphine, or N-heterocyclic carbene as the fourth ligand. Then, the second coordination site was used to introduce an IR-active rhenium tricarbonyl entity, affording the four corresponding heterobimetallic neutral PtII/ReI complexes, as well as a cationic PtII/ReI derivative. X-ray crystallographic studies showed that distortion of the organic platform occurred to accommodate the coordination geometry of both metal centers. No ligand exchange or transchelation occurred upon incubation of the PtII complexes in aqueous environment or in the presence of FeIII, respectively. The antiproliferative activity of the ligand and complexes was first screened on the triple-negative breast cancer cell line MDA-MB-231. Then, the IC50 values of the most active candidates were determined on a wider panel of human cancer cells (MDA-MB-231, MCF-7, and A2780), as well as on a nontumorigenic cell line (MCF-10A). Low micromolar activities were reached for the complexes carrying a DMSO ligand, making them the first examples of highly active, but hydrolytically stable, PtII complexes. Finally, the characteristic mid-IR signature of the {Re(CO)3} fragment in the Pt/Re heterobimetallic complexes was used to quantify their uptake in breast cancer cells. 相似文献
77.
经过半个世纪的发展,半导体技术不仅在制造功能强大的IC及各式各样的半导体分立器件方面,对社会发展起到不可估量的推动作用,而且对其他技术领域也产生了深刻的影响。在当前世界经济衰退浪潮的冲击下,无源电子元件领域借鉴、融合半导体技术以提高自身创新能力,加快产品升级是抵御冲击的值得关注的措施之一。 相似文献
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79.
在装配汽车前悬架与转向轮时需要拧紧螺纹,一旦操作不当就会出现前倾角过大的缺陷,加快车轮胎的磨损,降低小轴承及轮毂紧固螺母的使用寿命。对此,本文设计了一种基于PLC控制技术和气压传动控制技术的装配设备,能有效避免上述问题。 相似文献
80.
由于伴随着持续发展的自动控制、现代通信、计算机技术,这就逐步产生智能化建筑,所谓的智能小区则是扩展与延伸智能化大楼,人们往往借助优化考虑小区建筑群的服务、结构、管理、系统这四个基本要素,提供出一个便利、舒适、投资合理、安全、温馨、效率高的人居环境。以便可以将当前我国住宅建设科技含量增强与发展加快的要求。 相似文献