ConspectusOrganic photovoltaics (OPVs) have attracted considerable attention in the last two decades to overcome the terawatt energy challenge and serious environmental problems. During their early ...development, only wide-band-gap organic semiconductors were synthesized and employed as the active layer, mainly utilizing photons in the UV-visible region and yielding power conversion efficiencies (PCEs) lower than 5%. Afterward, considerable efforts were made to narrow the polymer donor band gap in order to utilize the infrared photons, which led to the enhancement of the PCE from 5% to 12% in about a decade. Since 2017, the study of narrow-band-gap non-fullerene acceptors helped usher in a new era in OPV research and boosted the achievable the PCE to 17% in only 3 years. In essence, the history of OPV development in the last 15 years can be summarized as an attempt to narrow the band gap of organic semiconductors and better position the energy levels. There are multiple benefits of a narrower band gap: (1) considerable infrared photons can be utilized, and as a result, the short-circuit current density can increase significantly; (2) the energy offset of the lowest unoccupied molecular orbital energy levels or highest occupied molecular orbital energy levels between the donor and acceptor can be reduced, which will reduce the open-circuit voltage loss by minimizing the loss caused by the donor/acceptor charge transfer state; (3) because of the unique molecular orbitals of organic semiconductors, the red-shifted absorption will induce high transmittance in the visible region, which is ideal for the rear subcells in tandem-junction OPVs and transparent OPVs.In this Account, we first summarize our work beginning in 2008 on the design and synthesis of narrow-band-gap polymer donors/non-fullerene acceptors. Several strategies for constructing these materials, including enhancing the intramolecular charge transfer effect and steric hindrance/energy level engineering are discussed. In this part, in addition to systematic analyses of the design of narrow-band-gap polymer donors based on BDT/TT or BDT/DPP, donors/acceptors based on the new donor moieties DTP or BZPT are discussed as well. Especially, we highlight our work on the first report on the narrow-band-gap acceptor Y1 (based on the new donor moiety BZPT), which pioneered the future development and usage of acceptors belonging to the Y1 family (or series). Subsequently, we analyze several reported certified world record single-junction or tandem-junction OPVs that use these narrow-band-gap donors or acceptors. We share our experiences and insights from a device perspective in terms of donor/acceptor selection, energy level alignment management, film morphology control, current matching of subcells, interconnecting layer construction, interface engineering, and device geometry selection. In this part, the construction of high-performance ternary-blend OPVs and transparent OPVs based on these narrow-band-gap donors/acceptors is also discussed. Finally, in order to push the field into the 20-25% high-efficiency era in the next few years, some suggestions to further develop narrow-band-gap donors/acceptors and related device technologies are proposed.
Ischemia-reperfusion injury is associated with serious clinical manifestations, including myocardial hibernation, acute heart failure, cerebral dysfunction, gastrointestinal dysfunction, systemic ...inflammatory response syndrome, and multiple organ dysfunction syndrome. Ischemia-reperfusion injury is a critical medical condition that poses an important therapeutic challenge for physicians. In this review article, we present recent advances focusing on the basic pathophysiology of ischemia-reperfusion injury, especially the involvement of reactive oxygen species and cell death pathways. The involvement of the NADPH oxidase system, nitric oxide synthase system, and xanthine oxidase system are also described. When the blood supply is re-established after prolonged ischemia, local inflammation and ROS production increase, leading to secondary injury. Cell damage induced by prolonged ischemia-reperfusion injury may lead to apoptosis, autophagy, necrosis, and necroptosis. We highlight the latest mechanistic insights into reperfusion-injury-induced cell death via these different processes. The interlinked signaling pathways of cell death could offer new targets for therapeutic approaches. Treatment approaches for ischemia-reperfusion injury are also reviewed. We believe that understanding the pathophysiology ischemia-reperfusion injury will enable the development of novel treatment interventions.
► ANCR level is significantly decreased during osteoblastic differentiation. ► ANCR downregulation promotes osteoblastic differentiation. ► ANCR is associated with enhancer of zeste homolog 2 (EZH2). ...► ANCR regulates Runx2 expression and osteoblast differentiation by EZH2.
Long noncoding RNAs (lncRNAs) are key regulators of diverse biological processes such as transcriptional regulation, cell growth and differentiation. Previous studies have demonstrated that the lncRNA-ANCR (anti-differentiation ncRNA) is required to maintain the undifferentiated cell state within the epidermis. However, little is known about whether ANCR regulates osteoblast differentiation. In this study, we found that the ANCR expression level is significantly decreased during hFOB1.19 cell differentiation. ANCR-siRNA blocks the expression of endogenous ANCR, resulting in osteoblast differentiation, whereas ANCR overexpression is sufficient to inhibit osteoblast differentiation. We further demonstrated that ANCR is associated with enhancer of zeste homolog 2 (EZH2) and that this association results in the inhibition of both Runx2 expression and subsequent osteoblast differentiation. These data suggest that ANCR is an essential mediator of osteoblast differentiation, thus offering a new target for the development of therapeutic agents to treat bone diseases.
The most fundamental concepts in chemistry are structure, energetics, reactivity and their inter-relationships, which are indispensable for promoting chemistry into a rational science. In this ...regard, bond energy, the intrinsic determinant directly related to structure and reactivity, should be most essential in serving as a quantitative basis for the design and understanding of organic transformations. Although C–H activation/functionalization have drawn tremendous research attention and flourished during the past decades, understanding the governing rules of bond energetics in these processes is still fragmentary and seems applicable only to limited cases, such as metal–oxo-mediated hydrogen atom abstraction. Despite the complexity of C–H activation/functionalization and the difficulties in measuring bond energies both for the substrates and intermediates, this is definitely a very important issue that should be more generally contemplated. To this end, this review is rooted in the energetic aspects of C–H activation/functionalization, which were previously rarely discussed in detail. Starting with a concise but necessary introduction of various classical methods for measuring heterolytic and homolytic energies for C–H bonds, the present review provides examples that applied the concept and values of C–H bond energy in rationalizing the observations associated with reactivity and/or selectivity in C–H activation/functionalization.
Advance care planning in Asian culture Cheng, Shao-Yi; Lin, Cheng-Pei; Chan, Helen Yue-lai ...
Japanese journal of clinical oncology,
09/2020, Volume:
50, Issue:
9
Journal Article
Peer reviewed
Open access
Abstract
Ageing has been recognized as one of the most critically important health-care issues worldwide. It is relevant to Asia, where the increasing number of older populations has drawn attention ...to the paramount need for health-care investment, particularly in end-of-life care. The advocacy of advance care planning is a mean to honor patient autonomy. Since most East Asian countries are influenced by Confucianism and the concept of ‘filial piety,’ patient autonomy is consequently subordinate to family values and physician authority. The dominance from family members and physicians during a patient’s end-of-life decision-making is recognized as a cultural feature in Asia. Physicians often disclose the patient’s poor prognosis and corresponding treatment options to the male, family member rather to the patient him/herself. In order to address this ethical and practical dilemma, the concept of ‘relational autonomy’ and the collectivism paradigm might be ideally used to assist Asian people, especially older adults, to share their preferences on future care and decision-making on certain clinical situations with their families and important others. In this review article, we invited experts in end-of-life care from Hong Kong, Indonesia, Japan, South Korea, Singapore and Taiwan to briefly report the current status of advance care planning in each country from policy, legal and clinical perspectives. According to the Asian experiences, we have seen different models of advance care planning implementation. The Asian Delphi Taskforce for advance care planning is currently undertaken by six Asian countries and a more detailed, culturally sensitive whitepaper will be published in the near future.
The discovery of modern medicine relies on the sustainable development of synthetic methodologies to meet the needs associated with drug molecular design. Heterocycles containing difluoromethyl ...groups are an emerging but scarcely investigated class of organofluoro molecules with potential applications in pharmaceutical, agricultural and material science. Herein, we developed an organophotocatalytic direct difluoromethylation of heterocycles using O
as a green oxidant. The C-H oxidative difluoromethylation obviates the need for pre-functionalization of the substrates, metals and additives. The operationally straightforward method enriches the efficient synthesis of many difluoromethylated heterocycles in moderate to excellent yields. The direct difluoromethylation of pharmaceutical moleculars demonstrates the practicability of this methodology to late-stage drug development. Moreover, 2'-deoxy-5-difluoromethyluridine (F
TDR) exhibits promising activity against some cancer cell lines, indicating that the difluoromethylation methodology might provide assistance for drug discovery.
Fluorine-containing moieties show significant effects in improving the properties of functional molecules. Consequently, efficient methods for installing them into target compounds are in great ...demand, especially those enabled by metal-free catalysis. Here we show a diazaphospholene-catalyzed hydrodefluorination of trifluoromethylalkenes to chemoselectively construct gem-difluoroalkenes and terminal monofluoroalkenes by simple adjustment of the reactant stoichiometry. This metal-free hydrodefluorination features mild reaction conditions, good group compatibility, and almost quantitative yields for both product types. Stoichiometric experiments indicated a stepwise mechanism: hydridic addition to fluoroalkenes and subsequent β-F elimination from hydrophosphination intermediates. Density functional theory calculations disclosed the origin of chemoselectivity, regioselectivity and stereoselectivity, suggesting an electron-donating effect of the alkene-terminal fluorine atom.
While many approaches to predict aqueous pKa values exist, the fast and accurate prediction of non‐aqueous pKa values is still challenging. Based on the iBonD experimental pKa database (39 solvents), ...a holistic pKa prediction model was established using machine learning. Structural and physical‐organic‐parameter‐based descriptors (SPOC) were introduced to represent the electronic and structural features of the molecules. The models trained with a neural network or the XGBoost algorithm showed the best prediction performance with a low MAE value of 0.87 pKa units. The approach allows a comprehensive mapping of all possible pKa correlations between different solvents and it was validated by predicting the aqueous pKa and micro‐pKa of pharmaceutical molecules and pKa values of organocatalysts in DMSO and MeCN with high accuracy. An online prediction platform was constructed based on the current model, which can provide pKa prediction for different types of X−H acidity in the most commonly used solvents.
Deep learning enables the holistic pKa prediction of various types of X−H acidities in 39 types of solvents. The accuracy of the predictions is demonstrated by a mean absolute error of 0.87 pKa units.
We described herein a catalyst‐free visible‐light photolytic protocol for the imidation of arenes and heteroarenes. N‐Bromosaccharin was identified as a viable and chemoselective nitrogen radical ...precursor that undergoes controllable homolytic cleavage under ambient light irradiation. The reaction can be applied to a number of arenes and heteroarenes with good chemo‐ and regioselectivity. Mechanistic studies revealed that radical chain termination by electron transfer‐proton transfer (ET‐PT) is the leading productive pathway for the reaction.
Light oN: Visible light was found to promote homolysis of N‐bromosaccharin. The generated imidyl radical undergoes facile homolytic substitutions with arenes and heteroarenes to give imidated adducts with good chemo‐ and regioselectivity. Mechanistic studies revealed that radical quenching by electron transfer–proton transfer (ET–PT) is the leading productive pathway for this CH imidation reaction (see scheme).
An asymmetric 1,6‐conjugate addition of thioacetic acid with para‐quinone methides has been developed by using chiral phosphoric acid catalysis in the presence of water. A series of sulfur‐containing ...compounds were thus obtained in high yields with good to excellent enantioselectivities. Theoretical studies indicated that the water‐bridged proton transfer is a potentially favorable reaction pathway. An unprecedented O−H⋅⋅⋅π interaction between water and the aromatic nucleus of chiral phosphoric acid was discovered to contribute significantly to the stereocontrol in the catalysis.
Building bridges: The title reaction was realized in the presence of water, and successfully solved the challenge of remote stereocontrol for the para‐quinone methide substrates. Theoretical studies indicated that the water‐bridged proton transfer and an unprecedented O−H⋅⋅⋅π interaction, between water and the aromatic nucleus of the chiral phosphoric acid, play important roles in the transition state.
PDF
