A nanoscale RGD-pyrene-graphene oxide (GO) biosensor was prepared for real-time in situ detection of a cancer cell surface marker, integrin αvβ3. This nanoscale GO-based biosensor is simple, robust, ...sensitive and of high selectivity. It can also be adapted to other cancer cell surface marker evaluation systems.
Driven by the increasing demand for electrochemical energy storage, lithium ion and lithium batteries have been the subject of tremendous scientific endeavors for decades. However, limited energy ...density, which is bottlenecked by available high‐density cathode materials, has become a critical issue to be solved. Recently, computational studies have played an increasingly important role in the search for the next‐generation high‐density cathode materials. Not only important insights on the battery chemistry have been revealed, but also novel material systems have been proposed. This review highlights recent progresses in the computational studies of cathode materials for lithium ion and lithium batteries. It starts from a brief introduction of the scientific background of lithium ion and lithium batteries, followed by a brief discussion of the working principles of batteries. Different computer simulation techniques are shown to originate from the same quantum mechanical treatment of many‐body systems with different levels of simplifications. Progresses in computational studies of different cathode materials, including intercalation electrode, conversion compounds, sulfur, and organosulfides, are then presented in detail. Finally, the capabilities of computational techniques in the study of cathode materials are summarized, and major challenges are discussed.
Computational methods are becoming increasing important in our search for high‐energy‐density electrode materials. This review showcases the versatility of atomistic simulations with a focus on cathode materials for lithium ion and lithium batteries. Progresses and challenges in the study of intercalation and conversion compounds, as well as sulfur and organosulfides, are discussed.
Drought and salinity are among the most important environmental factors that hampered agricultural productivity worldwide. Both stresses can induce several morphological, physiological, biochemical, ...and metabolic alterations through various mechanisms, eventually influencing plant growth, development, and productivity. The responses of plants to these stress conditions are highly complex and depend on other factors, such as the species and genotype, plant age and size, the rate of progression as well as the intensity and duration of the stresses. These factors have a strong effect on plant response and define whether mitigation processes related to acclimation will occur or not. In this review, we summarize how drought and salinity extensively affect plant growth in agriculture ecosystems. In particular, we focus on the morphological, physiological, biochemical, and metabolic responses of plants to these stresses. Moreover, we discuss mechanisms underlying plant-microbe interactions that confer abiotic stress tolerance.
Conspectus Synthetic macrocyclic hosts have played key roles in the development of host–guest chemistry. Crown ethers are a class of macrocyclic molecules with unique flexible structures. They have ...served as the first generation of synthetic hosts, and researchers have extensively studied them in molecular recognition. However, the flexible structures of simple crown ethers and their relatively limited modes of complexation with guests have limited the further applications of these molecules. In recent years, researchers have moved toward fabricating interlocking molecules, supramolecular polymers, and other assemblies with specific structures and properties. Therefore, researchers have developed more complex crown ether-based macrocyclic hosts with multicavity structures and multicomplexation modes that provide more diverse and sophisticated host–guest systems. In this Account, we summarize our research on the synthesis and characterization of iptycene-derived crown ether hosts, their use as host molecules, and their applications in self-assembled complexes. Iptycenes including triptycenes and pentiptycenes are a class of aromatic compounds with unique rigid three-dimensional structures. As a result, they are promising building blocks for the synthesis of novel macrocyclic hosts and the construction of novel self-assembled complexes with specific structures and properties. During the last several years, we have designed and synthesized a new class of iptycene-derived crown ether hosts including macrotricyclic polyethers, molecular tweezer-like hosts, and tritopic tris(crown ether) hosts, which are all composed of rigid iptycene building blocks linked by flexible crown ether chains. We have examined the complexation behavior of these hosts with different types of organic guest molecules. Unlike with conventional crown ethers, the combination of iptycene moieties and crown ether chains provides the iptycene-derived crown ether hosts with complexation properties that differ based on the structure of the guests. The rigid iptycene moieties within these synthetic host molecules both maintain their inherent three-dimensional cavities and generate multicavity structures. The flexible crown ether chains allow the iptycene-derived hosts to adjust their conformations as they encapsulate guest molecules. Moreover, the expanded complexation properties also allow the host–guest systems based on the iptycene-derived crown ethers to respond to multiple external stimuli, resulting in a variety of supramolecular assemblies. Finally, we also describe the construction of mechanically interlocked self-assemblies, molecular switches/molecular machines, and supramolecular polymers using these new host molecules. We expect that the unique structural features and diverse complexation properties of these iptycene-derived crown ether hosts will lead to increasing interest in this field and in supramolecular chemistry overall.
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•Pt/sepiolite catalysts were successfully prepared by a facile reductive impregnation.•Pt nanoparticles (2–4nm) were highly dispersed on sepiolite nanofibers (50–150nm).•The catalyst ...could efficiently degrade HCHO and showed a good stability for 7 cycles.•In situ DRIFTS was measured to study the catalytic oxidation mechanism of HCHO.•The synergistic effect of native hydroxyls and Pt nanoparticles is proposed.
Sepiolite nanofiber-supported platinum nanoparticle (Pt/sepiolite) catalysts were prepared by a reductive impregnation process, and were used for the efficient and stable removal of formaldehyde (HCHO). TEM and HRTEM analyses indicate that Pt nanoparticles with 2–4nm in size were highly dispersed on sepiolite nanofibers with diameters of 50–150nm. FTIR and XPS spectra show the presence of abundant hydroxyls on the catalyst surface. At ambient temperature, 1wt.% Pt/sepiolite catalyst calcined at 400°C exhibited the highest catalytic activity for the oxidation of HCHO to CO2 and H2O, and still showed a good performance even after 7 cycles. The mechanism of the catalytic oxidation of HCHO was studied through the behaviors of adsorbed species on the catalyst surface using in situ DRIFTS. The efficient and stable catalytic performance of the Pt/sepiolite catalyst mainly results from the synergistic effect between the hydroxyls on sepiolite nanofibers and highly dispersed Pt nanoparticles. This work may provide new insights for the application of noble metal catalysts supported on natural low-cost clays with special function groups in the removal of indoor air pollutants.
Sleep disturbances and dementia are two common and significant health problems in older adults. Investigations suggest that sleep disturbances might increase the risk of dementia. The aim of the ...present study was to systematically review and meta-analyze the predictive roles of overall sleep disturbances, their subtypes (e.g., insomnia, sleep disordered breathing SDB), and other sleep problems (e.g., excessive daytime sleepiness, sleep-related movement disorder, circadian rhythm sleep disorder, and nonspecific sleep problems) in incident all-cause dementia and Alzheimer's disease (AD) and vascular dementia subtypes. We performed a systematic search of the PubMed, EMBase, ISI Web of Science, and PsycINFO databases for longitudinal studies that were published up to October 28, 2016. A total of 12,926 papers were retrieved. Eighteen longitudinal studies that included 246,786 subjects at baseline and 25,847 dementia cases after an average 9.49 y of follow-up were eligible for inclusion. Compared with individuals without sleep disturbances, subjects who reported sleep disturbances had a higher risk of incident all-cause dementia, AD, and vascular dementia. The subgroup analysis showed that insomnia increased the risk of AD but not vascular or all-cause dementia. In contrast, SDB was associated with a higher incidence of all-cause dementia, AD, and vascular dementia. This meta-analysis suggests that sleep disturbances may predict the risk of incident dementia. Moreover, insomnia was associated only with incident AD, and SDB was a risk factor of all-cause dementia, AD, and vascular dementia. However, sleep disturbances were evaluated mainly based on self-reports, and some confounders may mediate the relationship between sleep disturbances and dementia. Therefore, the results should be further validated. In summary, these findings may help identify individuals who are at risk for dementia and optimize early prevention strategies.
Hansen, D. T. (2021). Reimagining the call to teach: A witness to teachers and teaching. Teachers College Press. David Hansen’s book Reimaging the Call to Teach: A Witness to Teachers and Teaching, ...in very nuanced, subtle, and complicated ways, inquires into teaching as a calling: it enacts and embodies the educational moments and space in teaching filled with uncertainties and complexities as “being with” (p. 33) others, “linking the past, present and future” (p. xiii). Hansen, as it rarely happens, bears an attuned and amplifying witness in sitting in on the classrooms as well as ongoing conversions to 16 public teachers over 2 years who participated in the “Person Project” (p. 52), which assembles teachers’ testimonials about teaching and what it means to “be a person in the world today” (p. 54) without imposing objectifying measurements and standards. In the book, the messy and rough ground of teaching, full of feelings, hesitations, and confusions, is not analyzed and decoded but rather felt, embodied, and described more comprehensively. As Hansen suggests, “I believe what is put forward here is a better description of the unity of the aesthetic, ethical, moral, and intellectual aspects of teaching—of the gestalt of teaching—of the meaning of teaching” (p. 57).
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