The existing literature has revealed many issues related to Ph.D. students' wellbeing, such as anxiety and stress, which are likely to cause Ph.D. student attrition or dropout. As one of the key ...coping strategies against psychological burnout, resilience has received increasing attention among various teacher groups. However, it still lacks a systematic understanding of students, in particular overseas Ph.D. students. This article explores doctoral students' resilience through a narrative inquiry into the resilience-building process of a Ph.D. student in language and linguistics, Hongxia, in the United Kingdom. Drawing on the research methods and results of resilience from teachers, this study examines Hongxia's lived experience as a Ph.D. student throughout her 3 years of learning and research and uncovers the dynamic and multifaceted process of resilience building as the interplay between Ph.D. students' agency, peers, supervisors, academics, families, and friends. The current research supports the value of narrative inquiry, in particular critical story analysis, as a tool for studying the resilience-building processes in Ph.D. students during their candidature. It also hopes to provide insight for administrators, supervisors, and other related stakeholders on their intervention to support and facilitate the research journey of doctoral students.
The carbon‐carbon (C—C) σ‐bonds construct the fundamental frameworks of organic molecules. The direct functionalization of C—C bonds represents one of the most efficient and step‐economical ...transformations in synthetic chemistry. The past few decades have witnessed the fast development of transition‐metal mediated C—C bond activation. In contrast, the radical‐promoted C—C bond cleavage has received relatively less attention. As the occurrence of ring strain significantly facilitates the fission of cyclic C—C bonds via radical approaches, the strain relief‐driven C—C bond activation mostly relies on the three‐ and four‐membered rings. The C—C activation of non‐strained molecules such as medium‐ or large‐sized rings and linear alkanes remains challenging. In this review, we will focus on the recent advances in radical‐mediated C—C bond activation of non‐strained molecules. Herein, the alkoxy‐ and iminyl‐radical triggered scission of non‐strained C—C bonds and C—C cleavage via the strategy of remote functional group migration is summarized.
The recent advances in radical‐mediated C—C bond activation of non‐strained molecules are summarized in this review. These transformations are mainly accomplished during the past three years, thus representing an emerging topic in organic chemistry. The alkoxy‐ and iminyl‐radical triggered cleavage of non‐strained C—C bonds and the C—C activation via the strategy of remote functional group migration are discussed in details.
Construction of C-C bonds via alkoxy radical-mediated remote C(sp
)-H functionalization is largely unexplored, as it is a formidable challenge to directly generate alkoxy radicals from alcohols due ...to the high bond dissociation energy (BDE) of O-H bonds. Disclosed herein is a practical and elusive metal-free alcohol-directed heteroarylation of remote unactivated C(sp
)-H bonds. Phenyliodine bis(trifluoroacetate) (PIFA) is used as the only reagent to enable the coupling of alcohols and heteroaryls. Alkoxy radicals are readily generated from free alcohols under the irradiation of visible light, which trigger the regioselective hydrogen-atom transfer (HAT). A wide range of functional groups are compatible with the mild reaction conditions. Two unactivated C-H bonds are cleaved and one new C-C bond is constructed during the reaction. This protocol provides an efficient strategy for the late-stage functionalization of alcohols and heteroaryls.
This narrative inquiry traces a Chinese college English teacher's cognitive transformation in the teaching-research nexus over a 4-year time period from the perspective of sociocultural theory (SCT). ...Several stories were narrated based on the data from reflective journals, literature reading notes, and interaction notes to show how the participant walked out of the teaching-research contradiction and finally achieved professional development. The findings indicate that the college English teacher's perception of the research-teaching nexus developed when she actively exercised her agency to take part in social interactions in a supportive sociocultural environment with the regulation of appropriate mediational tools. The conceptual progress in the research-teaching nexus finally contributed to her professional development in both teaching and research. The findings of this study have implications for non-key universities and their academics on how to effectively promote teaching-research integration.
Abstract
Understanding the variability of spatial extents of precipitation extremes favors an accurate assessment of the severity of disasters caused by extreme precipitation events. Using a ...restricted neighborhood method, we identify the spatial extents of global precipitation extremes over 1983–2018 and examine their spatiotemporal variability and associated changes. Results show that the mid-latitudes shows the largest spatial extent of precipitation extremes, and the spatial extents in non-tropical regions over the Northern Hemisphere show significant seasonal differences. In non-monsoon regions, the spatial extents of precipitation extremes in autumn and winter are larger than those in spring and summer, and the annual average spatial extents of precipitation extremes all exceed 500 km, which are larger than those in monsoon regions. All the five non-monsoon regions over the Northern Hemisphere and three monsoon regions in the western Pacific show statistically significant increases in the spatial extent of precipitation extremes in most seasons.
This exploratory research compares the interactive metadiscourse use by native English-speaking English for academic purposes (EAP) writing teachers in the United Kingdom and their non-native ...counterparts in the Chinese contexts. The analysis is based on a self-compiled corpus, including two sub-corpora, which were composed of instructor contributions to classroom discourse: eight sessions of EAP lessons from the Chinese context and eight sessions of EAP lessons from the British context. Adopting an interpersonal model of metadiscourse, the two sub-corpora were compared to examine the similarities and differences in their use of interactive metadiscourse. Findings of the comparative analysis reveal that EAP teachers from both contexts rely heavily on transition markers and frame markers to organize their teaching but differ in particular linguistic realizations. This may indicate the impact of a range of factors such as logical preferences, development order of acquisition, discourse community, and speech community on teachers’ interactive metadiscourse strategies. The article concludes with a few implications for metadiscourse research in spoken academic genres.
We report herein an efficient, general and green method for decarboxylative fluorination of aliphatic carboxylic acids. By using a transition-metal-free, organocatalytic photoredox system, the ...reaction of various aliphatic carboxylic acids with the Selectfluor reagent afforded the corresponding alkyl fluorides in satisfactory yields under visible light irradiation at room temperature.
Rational design of new bioisosteres through introduction of high-value functional groups to bicyclo1.1.1pentane (BCP) is of particular use for drug discovery. Disclosed herein is the first access to ...valuable fluoroalkylthio(seleno)-functionalized BCPs. A range of SCF
3
, SCF
2
H, SCFH
2
, SeCF
3
, SeC
4
F
9
, and SeC
8
F
17
groups are readily incorporated to BCPs under mild conditions. Concomitant installation of a sulfone provides a platform for incorporation of the BCP motif to bioactive molecules. This practical protocol features novel BCP scaffolds, broad substrate scope, excellent atom-economy, simple operation, and gram-scale preparation.
Conspectus Alkenes are ubiquitous in natural products and are extensively used as synthetic feedstocks in multiple fields including organic synthesis, medicinal chemistry, and materials science. ...Radical-mediated difunctionalization of alkenes provides a powerful tactic for alkene utilization. Despite the considerable progress made in the past several decades, state-of-the-art methods are highly dependent upon activated alkenes in which a proximal group with a π-electron system (e.g., aryl, carbonyl, and heteroatom) is requisite to stabilize the nascent alkyl radical intermediate via p−π conjugation or p orbitals of the heteroatom. In contrast, the transformation of unactivated alkenes, such as aliphatic alkenes, remains challenging. To overcome this obstacle, we have recently disclosed the strategy of intramolecular distal functional group migration (FGM), which has been efficiently applied in radical difunctionalization of unactivated alkenes. A portfolio of functional groups, such as cyano, heteroaryl, oximino, formyl, and alkynyl groups, showcase the excellent migratory aptitude. Mechanistically, after the addition of an extrinsic radical to the alkene, the newly formed active alkyl radical is rapidly captured by the intramolecular migratory group to generate a cyclic intermediate. Subsequent cleavage of the cyclic C–C bond of the intermediate leads to the functionalized product through the FGM process. Based on the strategy of FGM, a set of elusive difunctionalizations of unactivated alkenes have been accomplished (Part A). Alongside this research, an upgraded highly efficient synthetic strategy, “dock-migration,” is created for intermolecular difunctionalization of alkenes. A diversity of sulfone-based dual-function reagents are developed. The intermolecular transformation is initiated by docking the dual-function reagent to the alkene, followed by intramolecular migration of the functional group. Compared to the original FGM protocol, the scope of alkenes is significantly extended from the strategically placed tertiary alcohol-substituted alkenes to general alkenes. Both activated and unactivated alkenes are well tolerated. By this approach, radical-mediated fluoroalkylheteroarylation, fluoroalkylalkynylation, and alkylation of alkenes have been achieved (Part B). Direct elaboration of C–H bonds into the targeted functional groups represents one of the most ideal and straightforward methods for molecular functionalization. The FGM strategy proves to be an ingenious tool for radical-mediated functionalization of remote unactivated C(sp3)–H bonds. Based on the FGM process, we have accomplished: (a) remote C(sp3)–H heteroarylation and cyanation of unprotected alcohols via the cascade of alkoxy radical-enabled hydrogen atom transfer (HAT) and intramolecular functional group (e.g., heteroaryl, cyano) migration, and (b) distal C(sp3)–H vinylation of propargylic alcohols through consecutive alkenyl radical-promoted HAT process and subsequent alkenyl migration (Part C).
Precipitation whiplash, including abrupt shifts between wet and dry extremes, can cause large adverse impacts on human and natural systems. Here we quantify observed and projected changes in ...characteristics of sub-seasonal precipitation whiplash and investigate the role of individual anthropogenic influences on these changes. Results show that the occurrence frequency of global precipitation whiplash is projected to be 2.56 ± 0.16 times higher than in 1979-2019 by the end of the 21
Century, with increasingly rapid and intense transitions between two extremes. The most dramatic increases of whiplash show in the polar and monsoon regions. Changes in precipitation whiplash show a much higher percentage change than precipitation totals. In historical simulations, anthropogenic greenhouse gas (GHG) and aerosol emissions have increased and decreased precipitation whiplash occurrences, respectively. By 2079, anthropogenic GHGs are projected to increase 55 ± 4% of the occurrences risk of precipitation whiplash, which is driven by shifts in circulation patterns conducive to precipitation extremes.
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