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Interaction-dependent photophysical behavior of two-component ensembles arising from conjugated polyelectrolytes and platinum(II) complexes of different supramolecular architectures
No full textRecent works have shown that cationic alkynylplatinum(II) 2,6-bis(benzimidazol-2′-yl)pyridine (bzimpy) complexes possess the capability of undergoing electrostatic assembly with anionic conjugated polyelectrolytes (CPEs) to form two-component supramolecular ensembles. However, previous studies on the FRET properties of CPEs were mainly focused on and restricted to rigid and extended π-conjugated polymers, while little discussions have been made on those with flexible linkers or interrupted π-conjugation. Moreover, the mechanism for the reciprocal interactions between the CPE and platinum(II) complexes in the formation of the ensemble is essentially less explored. Therefore, in order to have a more in-depth understanding and to provide further insights into these processes, a CPE with interrupted π-conjugation, poly(phenylene ethynylene sulfonate) with a diphenyl ether unit (bPPE-SO3–), has been employed to induce the formation of supramolecular aggregates of alkynylplatinum(II) bzimpy complexes in aqueous buffer solution. The formation of the two-component CPE–platinum(II) complex ensembles via electrostatic, Pt∙∙∙Pt and π–π stacking interactions has been investigated by UV-vis absorption, steady-state emission, resonance light scattering, and time-resolved emission experiments. Interestingly, the reciprocal interactions, energy transfer processes and the resultant photophysical properties of the two-component ensemble comprising bPPE-SO3– and [Pt(bzimpy-Et){C≡CC6H4(CH2NMe3-4)}]Cl2 (1) have been found to be distinctively different when compared to those formed by 1 with a structurally similar CPE, PPE-SO3–. The conformational flexibility and geometrical features imparted by the –O– linker of bPPE-SO3– has empowered it with the capability in forming strong bPPE-SO3––1 aggregates, as evidenced by the large Stern–Volmer constants in the presence of 1 at low concentrations. Due to the combination of a relatively large Fӧrster radius, high triplet state energy of bPPE-SO3– as well as large HOMO–LUMO energy gap, photo-induced charge transfer (PCT) and Dexter triplet energy back transfer (TEBT) quenching of the emission of platinum(II) complexes would be effectively suppressed. This would facilitate efficient Fӧrster resonance energy transfer (FRET) process between bPPE-SO3– and aggregate form of complex molecules of 1, leading to the emergence of triplet metal–metal-to-ligand charge transfer (3MMLCT) emission. In stark contrast, the weaker PPE-SO3––1 aggregates that possibly exhibit more efficient PCT and Dexter TEBT quenching would lead to the absence of 3MMLCT emission in the PPE-SO3––1 ensemble. It is anticipated that these results would open up a new avenue and provide new strategies for the construction of two-component CPE–metal complex ensembles with optimized FRET efficiency. Moreover, the mechanisms for the reciprocal interactions between the CPEs and the platinum(II) complexes have been found to be dependent on their intrinsic structural and geometrical features as well as their extrinsic supramolecular architectures. In particular, bPPE-SO3– is found to exhibit a multiple-step emission spectral response with an increasing concentration of 1. Similar observations have not been encountered before in the meta-linked poly(phenylene ethynylene) containing alanine pendant (mPPE-Ala) counterpart. The result has been rationalized by the structural non-coplanarity of bPPE-SO3–, at which the twisted –O– linker in the bPPE backbone would weaken the intramolecular hydrophobic and π–π stacking interactions and thus, become more susceptible towards the perturbations brought about by the microenvironmental changes. In comparison, the strong intramolecular hydrophobic and π–π stacking interactions between the adjacent gyrations of mPPE-Ala would strengthen its helical conformation, making it less responsive towards external stimuli. The current study demonstrates the versatility of this class of two-component stimuli-responsive CPE-platinum(II) complex ensembles in diverse applications. It is envisaged that the above results should emerge as a prime driving force for initiating further studies in exploring their potential sensing or imaging applications by providing valuable information on the photophysical properties of the ensembles
Ruthenium-Catalyzed Cycloaddition of Azides and Selenoalkynes with Built-in “Catch-and-Release” Functionality
No full textClick reactions with a “catch-and-release” functionality featuring both cross-linking and bond cleavage may have unique biomedical applications. However, despite the high demand, such reactions are rarely known in the toolbox of biochemists. Herein we introduce a robust click reaction of selenoalkynes that not only facilitates mild cross-linking with azides but also permits exceptionally facile cleavage of the C─Se bond in the adducts. This highly efficient ruthenium-catalyzed protocol features high chemoselectivity and regioselectivity, mild conditions, broad substrate scope, and good tolerance of functional groups and solvents. The compatibility with air and water as well as biomolecules has been demonstrated in parallel with the “catch-and-release” functionality
Effort Redirection Across Multiple Career Tracks: Salary-Cut Policy and State-Owned Enterprises in China
No full textPrior literature in agency theory assumes that when incentives decrease, agents may shirk and reduce effort. We extend this work to multiple career tracks and suggest that a salary decrease may not necessarily lead to effort reduction, but instead may redirect efforts across multiple career tracks. Using an exogenous salary-cut policy shock levied on top executives of Chinese central state-owned enterprises (SOEs), our difference-in-differences analysis reveals that salary cuts motivate SOE top executives to redirect efforts from improving internal management (i.e., operational efficiency) to political objectives (i.e., job creation). A further test reveals that job creation mediates the relationship between salary cuts and SOE top executives’ political appointments. Moreover, top executive age, as an indicator of political incentive, and media coverage, which reflects external monitoring, weaken the impact of the salary-cut policy on effort redirection between the two career tracks. These findings provide implications for research on agency theory, SOEs, and public policy
Exploring the influential factors of online professional learning completion of college teachers from the Global South in an international training program
No full textOnline courses emerged as an important mode for large-scale cross-national teachers' professional learning. However, with most previous research on teacher online professional learning (TOPL) focusing on resource-rich and technology-advanced regions, little attention has been paid to the factors influencing the online learning completion of college teachers in Global South contexts. This study aimed to explore the facilitators and inhibitors of this population's online learning completion in a cross-country program. In seven courses, individual, institutional, and country-level data of 3529 teacher-learners from 99 countries were collected. Forty-two learners were further interviewed. We adopted hierarchical linear modeling to analyze the nested relationships among the individual/institutional/country-level factors and course completion. Results revealed several significant associations between individual/institutional/country-level variables and course completion, as well as several moderation effects. Interviews complemented the analytics results. This study uncovers influential factors of TOPL in Global South contexts and provides practical implications for college teachers' online professional learning
Examining the social distributions in neighbourhood black carbon and ultrafine particles in Montreal and Toronto, Canada
No full textBackground: Socioeconomic inequities in outdoor ultrafine particles (UFP) and black carbon (BC) are understudied in Canada, where metropoles like Montreal and Toronto feature distinct sociodemographic diversity and urban characteristics compared to U.S. cities. Methods: We collected vulnerability indicators, including social, economic, household composition, and immigration status, at the dissemination area level for Montreal and Toronto using data from the 2006 and 2021 Canadian Census of Population. Areas were classified as disadvantaged, intermediate, or advantaged following K-means clustering analysis. We aggregated and calculated population-weighted average concentrations of BC and UFP, and UFP size at the dissemination area and cluster levels using high-resolution exposure surfaces, derived from year-long mobile monitoring campaigns conducted in each city during 2020–2021. Final exposure surfaces were generated by integrating predictions from land-use regression models and deep convolutional neural network models. Findings: We observed high within-city variations in aggregated air pollutant levels, with higher outdoor BC and UFP concentrations and smaller UFP sizes in areas near local sources such as major roads, railways, airports, and densely populated regions. Advantaged areas experienced the lowest median UFP concentrations in both Montreal (10,707 pt/cm3) and Toronto (10,988 pt/cm3), as well as the lowest BC concentrations (650 ng/m3) in Montreal. The highest median UFP concentrations were observed in intermediate areas in Montreal (15,709 pt/cm3) and disadvantaged areas in Toronto (12,228 pt/cm3). Conversely, the highest BC concentrations were observed in disadvantaged and intermediate areas in Montreal (805–811 ng/m3), and disadvantaged and advantaged areas in Toronto (1,228–1,252 ng/m3). Notably, high priority areas for the double burden of vulnerability and high BC and UFP concentrations were located near air pollutants local emission sources. Interpretation: Our findings highlight the importance of prioritizing exposure mitigation for populations residing near local sources and to understand contextual factors influencing inequities across cities and pollutants
Pharmacoeconomic inequalities in access to antifibrotic treatment for interstitial lung disease in the Asia-Pacific region
No full textAntifibrotic drugs, available for the best part of the last decade in many parts of the world, have improved outcomes in patients with idiopathic pulmonary fibrosis and progressive pulmonary fibrosis. However, it is unclear whether patients suffering from these devastating conditions have timely and adequate access to antifibrotic therapy in the Asia-Pacific region (APAC). In this mixed-methods narrative review of 12 APAC countries, integration of questionnaire-based insights of 31 regional clinical experts in interstitial lung disease (ILD) with publicly available pharmaco-economic information has been used to understand how country-specific challenges impact on antifibrotic accessibility. Overall, a broad range of approaches are utilized to provide antifibrotic treatment including centrally or state-determined drug budgets, pharmaceutical industry-subsidized initiatives, charitable support and self-paying (out-of-pocket) options. Impediments to antifibrotic access commonly arise from prohibitive drug pricing in relation to income, absence of universal coverage for pharmaceutical costs, lack of formal pharmaco-economic analysis or restrictions on the use of generic preparations. Unequal access to antifibrotic drugs is a vital unmet therapeutic need in the APAC region, one that is likely to be exacerbated by a rising fibrotic ILD burden.</p
The synergistic effect of c-Myb hyperactivation and Pu.1 deficiency induces Pelger–Huët anomaly and promotes sAML
No full textApproximately 30% of patients with myelodysplastic syndrome (MDS) progress to secondary acute myeloid leukemia (sAML) via accumulating gene mutations. Genomic analyses reveal a complex interplay among mutant genes, with co-occurring and mutually exclusive patterns. Hyperactivation of c-MYB and deficiency of PU.1 have been linked to myeloid disorders. We report a case of AML with concurrent PU.1 and c-MYB mutations, exhibiting early onset, high blast count, chemo-resistance, indicating high-risk features, along with elevated Pelger–Huët anomaly (PHA). However, the synergistic mechanism of c-MYB and PU.1 in sAML remains unclear. Using c-Myb-hyperactivation and Pu.1-deficient double-strain (c-mybhyper;pu.1G242D/G242D) zebrafish, we investigated MDS/sAML progression. Surprisingly, the double mutant exhibited a distinct type of neutrophil resembling clinical PHA cells and demonstrated a higher rate of MDS/ sAML transformation. Further expression analysis revealed reduced lmnb1 expression in double-mutant zebrafish. Knockdown of lmnb1 resulted in PHA and increased blast cells, while overexpression of lmnb1 in c-mybhyper;pu.1G242D/G242D reduced PHA cell level. This suggests that c-Myb hyperactivation and Pu.1 deficiency synergistically reduce lmnb1 expression, inducing the development of PHA-like neutrophils and promoting MDS/sAML progression in zebrafish. Moreover, coadministration of cell cycle inhibitor cytarabine (Ara-C) and the differential inducer all-trans retinoic acid (ATRA) could effectively relieve the neutrophil expansion and PHA symptoms in c-mybhyper;pu.1G242D/G242D zebrafish. Our findings revealed that c-Myb hyperactivation and Pu.1 deficiency played a synergistic role in sAML development and suggests a phenotypic association between the emergence of PH-like cells and the transformation to sAML. Furthermore, c-mybhyper;pu.1G242D/G242D zebrafish might serve as a suitable sAML model for drug screening.</p
"Property" as Polyseme & Its Implications for Trust "Property"
No full textThe trust may be English law’s “greatest and most distinctive achievement … in the field of jurisprudence” but it is likely to also be its most confounding. A fierce debate - often cast in dualistic terms - has raged for more than a century over whether a beneficiary’s interest under a trust is proprietary or obligational. Upon closer examination, some of the disagreements are less substantive and more semantic. At the heart of this debate lies the ambiguity inherent in the meaning of the word “property” itself. Yet, although equitable “property” may not be identical to legal “property” (indeed, tangible legal “property” is fundamentally different from intangible legal “property”), this does not make it any less properly regarded as “property”. Rather than being a mere mimic or metaphor, equitable “property” simply secures exclusive control to a resource in a different, indirect, manner for equitable “owners”. “Property” is a polyseme, where a word has different meanings but those meanings are related so that even though it is different from legal “property”, it is no less truly “property”. The primary objective of this clarification is to serve as a via media to reconcile some of the apparently opposing views that have arisen in this debate. However, it also pushes back against certain revisionist reforms proposed for equitable “property” that fail to acknowledge the fundamentally different nature of equitable "property" to legal "property". The understanding of equitable “property” proposed also carries implications for the English Law Commission's conception of digital assets as third things that supposedly carry no rights until they are interfered with.</p
Vitamin D status and its determinants among Chinese infants and toddlers in Hong Kong
No full textPurpose: Vitamin D is a micronutrient that is necessary for bone health as well as the regulation of mineral homeostasis. This study aims to assess the vitamin D status and its determinants among infants and toddlers in Hong Kong, two of the most vulnerable groups at risk of vitamin D insufficiency. Methods: A multi-centre cross-sectional study recruiting 887 infants and toddlers was conducted. A comprehensive assessment on potential factors that can influence vitamin D status as well as serum vitamin D concentration was conducted for all participants. Regression analyses were conducted to assess the factors contributing to the vitamin D insufficiency risk. Results: 124 (14.0%) infants and toddlers were vitamin D insufficient and 44 (5.0%) were vitamin D deficient, with higher prevalence observed among younger infants (aged 2 to 6 months). Majority did not consume any vitamin D-containing supplement (86.5%) which was associated with higher risk of vitamin D insufficiency (aOR = 2.16, p = 0.017). An increment of 100IU in total daily vitamin D intake lowered the risk of vitamin D insufficiency (aOR = 0.50, p < 0.001) in older infants and toddlers. Being breastfed increased vitamin D insufficiency risk in younger infants (aOR = 24.91, p < 0.001) and in older infants and toddlers (aOR = 7.36, p < 0.001). Further analyses identified distinctive pattern among factors that can influence 25(OH)D3, 25(OH)D2, and 3-epi-25(OH)D3 concentrations. Conclusion: Low total vitamin D intake and lack of supplementation practice were the key contributing factors to vitamin D insufficiency among infants and toddlers in Hong Kong. Detailed guidelines and support should be provided to meet their respective daily vitamin D intake requirement to further tackle the vitamin D insufficiency and deficiency among these vulnerable populations
Pareto-optimal peer-to-peer risk sharing with robust distortion risk measures
No full textWe study Pareto optimality in a decentralized peer-to-peer risk-sharing market where agents' preferences are represented by robust distortion risk measures that are not necessarily convex. We obtain a characterization of Pareto-optimal allocations of the aggregate risk in the market, and we show that the shape of the allocations depends primarily on each agent's assessment of the tail of the aggregate risk. We quantify the latter via an index of probabilistic risk aversion, and we illustrate our results using concrete examples of popular families of distortion functions. As an application of our results, we revisit the market for flood risk insurance in the United States. We present the decentralized risk sharing arrangement as an alternative to the current centralized market structure, and we characterize the optimal allocations in a numerical study with historical flood data. We conclude with an in-depth discussion of the advantages and disadvantages of a decentralized insurance scheme in this setting.link_to_subscribed_fulltex