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41.
Oxoisoaporphine Alkaloids: Prospective Anti‐Alzheimer's Disease,Anticancer, and Antidepressant Agents 下载免费PDF全文
Oxoisoaporphine alkaloids are a family of oxoisoquinoline‐derived alkaloids that were first isolated from the rhizome of Menispermum dauricum DC. (Menispermaceae). It has been demonstrated that oxoisoaporphine alkaloids possess various biological properties, such as cholinesterase and β‐amyloid inhibition, acting as a topoisomerase intercalator, monoamine oxidase A inhibition, and are expected to become anti‐Alzheimer's disease, anticancer, and antidepressant drugs. This review provides an overview of natural sources, synthetic routes, bioactivities, structure–function relationship, and modification investigations into oxoisoaporphine alkaloids, with the aim of providing references to the structure–activity relationships for the design and development of oxoisoaporphine derivatives with higher efficacy and therapeutic potential. 相似文献
42.
Dr. Lei Huang Jan Philipp Bittner Dr. Pablo Domínguez de María Dr. Sven Jakobtorweihen Prof. Dr. Selin Kara 《Chembiochem : a European journal of chemical biology》2020,21(6):811-817
The use of oxidoreductases (EC1) in non-conventional reaction media has been increasingly explored. In particular, deep eutectic solvents (DESs) have emerged as a novel class of solvents. Herein, an in-depth study of bioreduction with an alcohol dehydrogenase (ADH) in the DES glyceline is presented. The activity and stability of ADH in mixtures of glyceline/water with varying water contents were measured. Furthermore, the thermodynamic water activity and viscosity of mixtures of glyceline/water have been determined. For a better understanding of the observations, molecular dynamics simulations were performed to quantify the molecular flexibility, hydration layer, and intraprotein hydrogen bonds of ADH. The behavior of the enzyme in DESs follows the classic dependence of water activity (aW) in non-conventional media. At low aW values (<0.2), ADH does not show any activity; at higher aW values, the activity was still lower than that in pure water due to the high viscosities of the DES. These findings could be further explained by increased enzyme flexibility with increasing water content. 相似文献
43.
Yury S. Nechaev N. M. Alexandrova N. A. Shurygina A. O. Cheretaeva 《Fullerenes, Nanotubes and Carbon Nanostructures》2020,28(3):233-237
AbstractSome experimental evidences and the physics (thermodynamics) of the nanoscale self-intercalation of high-density gaseous molecular hydrogen (ρ?≈?0.045?g/cm3, T?≈?300?K) into surface nanoclusters in highly oriented pyrolytic graphite and epitaxial graphene, as well as the nanoscale self-intercalation of high density solid molecular hydrogen (ρ?≈?0.5?g/cm3, T?≈?300?K, the compressed pressure ~ 0.5 Mbar) into graphite nanofibers are considered, with regard to the problem of compact and efficient hydrogen on-board storage and other clean energy applications. Perspectives of further developments of these results are considered, as well. 相似文献
44.
针对煤矿发生事故后传统救援监控系统无法实时对井下人员进行动态定位,导致矿井救援盲目性大、救援效率差、救援难度大等技术难题,为了进一步提高煤矿救援效率,通过技术研究,设计了一套以通信基站为核心的智能化救援监控系统,分析了该系统结构组成、工作原理,通过在担水沟煤矿井下实际应用效果来看,智能化救援监控系统对人员定位精准度达95%,实现人员动态位置三维成像,救援效率提高至80%以上,有效缩短了煤矿事故救援时间,取得了显著应用成效。 相似文献
45.
46.
The temperature-dependent electrical and charge transport characteristics of pentacene-based ambipolar thin-film transistors (TFTs) were investigated at temperatures ranging from 77 K to 300 K. At room temperature (RT), the pentacene-based TFTs exhibit balanced and high charge mobility with electron (μe) and hole (μh) mobilities, both at about 1.6 cm2/V s. However, at lower temperatures, higher switch-on voltage of n-channel operations, almost absent n-channel characteristics, and strong temperature dependence of μe indicated that electrons were more difficult to release from opposite-signed carriers than that of holes. We observed that μe and μh both followed an Arrhenius-type temperature dependence and exhibited two regimes with a transition temperature at approximately 210–230 K. At high temperatures, data were explained by a model in which charge transport was limited by a dual-carrier release and recombination process, which is an electric field-assisted thermal-activated procedure. At T < 210 K, the observed activation energy is in agreement with unipolar pentacene-based TFTs, suggesting a common multiple trapping and release process-dominated mechanism. Different temperature-induced characteristics between n- and p-channel operations are outlined, thereby providing important insights into the complexity of observing efficient electron transport in comparison with the hole of ambipolar TFTs. 相似文献
47.
Mari Lee Mifsud 《Review of Communication》2019,19(2):77-93
ABSTRACTThis special issue of Review of Communication presents new offerings of the study of communication, forging present and future humanities. This Introduction engages the six essays in this special issue—which extend and intersect across categories of the humanistic study of communication: communication philosophy and ethics, rhetorical theory, history, pedagogy, criticism, and digital humanities—to explore their contributions in defense of the humanities. Taken together, these essays explore the study of communication as (1) a resource for inquiring and exchanging with concepts, practices, and embodiments of difference, the other, and the posthuman; (2) a means of examining the ontological, epistemological, technological, existential, performative, and ethical implications of our communicative being, our being constituted by symbolic action and mediated exchange in ever-present yet always variant material and affective environments, spaces, and places; (3) a discipline emerging from rhetoric, one of the original liberal arts, yet developing in transdisciplinary ways, transforming the binary of humanities and sciences; (4) a tool for decolonizing knowledge(s); (5) a tool for exploring, critiquing, engaging, and creating with the new media of our digital lives together; (6) a long-standing yet ever inventive method and mode for public humanities; and (7) a praxis of resistance. These essays bring to light what studying communication offers the humanities: a plural, public, reflexive, and ever inventive enterprise for examining being human together on this planet. 相似文献
48.
In order to meet the growing demand of portable electronic devices and electric vehicles, enhancements in battery performance metrics are required to provide higher energy/power densities and longer cycle lives, especially for anode materials. Alloying anodes, such as Group IVA elements-based materials, are attracting increasing interest as anodes for next-generation high-performance alkali-metal-ion batteries (AMIBs) owing to their extremely high specific capacities, low working voltages, and natural abundance. Nevertheless, alloying-type anodes usually display unsatisfactory cycle life due to their intrinsic violent volumetric and structural changes during the charge–discharge process, causing mechanical fracture and exacerbating side reactions. In order to overcome these challenges, efforts have been made in recent years to manufacture multimetallic anodes that can accommodate the induced strain, thus showing high Coulomb efficiency and long cycle life. Meanwhile, much work has been conducted to understand the details of structural changes and reaction mechanisms taking place by in-situ characterization methodologies. In this paper, we review the various recent developments in multimetallic anode materials for AMIBs and shed light on optimizing the anode materials. Finally, the perspectives and future challenges in achieving the practical applications of multimetallic alloy anodes in high-energy AMIB systems are proposed. 相似文献
49.
Degradation data have been widely used for the remaining useful life (RUL) prediction of systems. Most existing works apply a preset model to capture the degradation process and focus on the degradation process without shocks or constant shock effects. More generally, the actual degradation path is unobservable due to the existence of measurement uncertainty, which interferes with the determination of the degradation model. Besides, the effect of random shocks is usually fluctuating. Given these problems, a general degradation model with the random shock fluctuant effects considering the measurement uncertainty is first developed to describe the degradation process, and a two-step approach combining the arithmetic average filter and the Bayesian information criterion is adopted to identify the degradation path. Subsequently, the transfer processes of the actual degradation state and the abrupt change caused by shocks are depicted using a two-dimensional state-space model, and an expectation-maximization algorithm combined with the particle filtering is developed for parameter estimation. Furthermore, the explicit solution of RUL distribution is obtained when only considering harmful shocks, while a simulation method of RUL distribution is provided when both harmful and beneficial shocks exist. Finally, the effectiveness of the proposed method is verified by a numerical example and two practical case studies. 相似文献
50.