Selective C-C bond cleavage under mild conditions can serve as a valuable tool for organic syntheses and macromolecular degradation. However, the conventional chemical methods have largely involved ...the use of noble transition-metal catalysts as well as the stoichiometric and perhaps environmentally unfriendly oxidants, compromising the overall sustainable nature of C-C transformation chemistry. In this regard, electrochemical C-C bond cleavage has been identified as a sustainable and scalable strategy that employs electricity to replace byproduct-generating chemical reagents. To date, the progress made in this area has mainly relied on Kolbe electrolysis and related processes. Encouragingly, more and more examples of the cleavage of C-C bonds via other maneuvers have recently been developed. This review provides an overview on the most recent and significant developments in electrochemically oxidative selective C-C bond cleavage, with an emphasis on both synthetic outcomes and reaction mechanisms, and it showcases the innate advantages and exciting potentials of electrochemical synthesis.
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An efficiently stereoselective 4 + 2 cycloaddition of 3-alkylenyloxindoles and α-diazoketones through sequential visible-light photoactivation and
-heterocyclic carbene catalysis was achieved. A ...series of tetrahydropyrano2,3-
indoles with an all-carbon quaternary stereocenter were obtained in good yields with excellent diastereo- and enantioselectivities.
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The enantioselective 3+4 annulation of 3-formylindol-2-methyl-malonates with 2-bromoenals catalyzed by NHCs is described to afford functionalized azepino1,2-aindoles in high yields with excellent ...enantioselectivities. This method, in which the 3-formyl group in indoles acts as a necessary mediating group, provided cycloaddition products under mild conditions.
Infrared nonlinear optical (IR NLO) materials are significant in laser technology for civil and military uses. Here, we report the synthesis, structural chemistry and NLO properties of a halogen‐rich ...chalcohalide Sn7Br10S2. Its noncentrosymmetric (NCS, P63) structure can be considered as partially aliovalent anion substitution of SnBr2 (P63/m) induced centrosymmetric (CS) to NCS structural transformation. The 3D ∞Sn(1)6Sn(2)6Br6X66− (X=Br/S) channel framework consists of Sn(1)BrX2 and Sn(2)X3 trigonal pyramids. It exhibits excellent NLO performance, including a strong phase‐matchable NLO response of 1.5 × AgGaS2and high laser‐induced damage threshold of 6.3 × AgGaS2.Investigation of the structure–NLO performance relationship confirms that the effective arrangement of Sn(1)BrX2 and Sn(2)X3 units predominantly contributes to the large SHG response. These results indicate Sn7Br10S2 is a potential IR NLO candidate and provides a new feasible system for promising NLO materials.
The first ternary halogen‐rich nonlinear optical chalcohalide Sn7Br10S2 exhibits a strong phase‐matchable second‐harmonic generation response (1.5 × AGS@2.1 μm) and high laser‐induced damage threshold (6.3 × AGS). This work provides a competitive candidate with good performance, facile synthesis and simple chemical composition for infrared nonlinear optical (IR NLO) applications, and also introduces a facile strategy to obtain high‐performance NLO materials via a symmetry break.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
There is an urgent need for vaccines against coronavirus disease 2019 (COVID-19) because of the ongoing SARS-CoV-2 pandemic. Among all approaches, a messenger RNA (mRNA)-based vaccine has emerged as ...a rapid and versatile platform to quickly respond to this challenge. Here, we developed a lipid nanoparticle-encapsulated mRNA (mRNA-LNP) encoding the receptor binding domain (RBD) of SARS-CoV-2 as a vaccine candidate (called ARCoV). Intramuscular immunization of ARCoV mRNA-LNP elicited robust neutralizing antibodies against SARS-CoV-2 as well as a Th1-biased cellular response in mice and non-human primates. Two doses of ARCoV immunization in mice conferred complete protection against the challenge of a SARS-CoV-2 mouse-adapted strain. Additionally, ARCoV is manufactured as a liquid formulation and can be stored at room temperature for at least 1 week. ARCoV is currently being evaluated in phase 1 clinical trials.
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•Development of LNP-encapsulated mRNA vaccine (ARCoV) targeting the RBD of SARS-CoV-2•ARCoV induces neutralizing antibodies and T cell immunity in mice and NHPs•ARCoV vaccination confers full protection against SARS-CoV-2 challenge in mice•ARCoV is a thermostable vaccine candidate for phase I studies
ARCoV is an LNP-encapsulated mRNA vaccine platform that is highly immunogenic and safe in mice and non-human primates, conferring protection against challenge with a SARS-CoV-2 mouse-adapted strain.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Lysophosphatidylcholine (LPC) is increasingly recognized as a key marker/factor positively associated with cardiovascular and neurodegenerative diseases. However, findings from recent clinical ...lipidomic studies of LPC have been controversial. A key issue is the complexity of the enzymatic cascade involved in LPC metabolism. Here, we address the coordination of these enzymes and the derangement that may disrupt LPC homeostasis, leading to metabolic disorders. LPC is mainly derived from the turnover of phosphatidylcholine (PC) in the circulation by phospholipase A₂ (PLA₂). In the presence of Acyl-CoA, lysophosphatidylcholine acyltransferase (LPCAT) converts LPC to PC, which rapidly gets recycled by the Lands cycle. However, overexpression or enhanced activity of PLA₂ increases the LPC content in modified low-density lipoprotein (LDL) and oxidized LDL, which play significant roles in the development of atherosclerotic plaques and endothelial dysfunction. The intracellular enzyme LPCAT cannot directly remove LPC from circulation. Hydrolysis of LPC by autotaxin, an enzyme with lysophospholipase D activity, generates lysophosphatidic acid, which is highly associated with cancers. Although enzymes with lysophospholipase A₁ activity could theoretically degrade LPC into harmless metabolites, they have not been found in the circulation. In conclusion, understanding enzyme kinetics and LPC metabolism may help identify novel therapeutic targets in LPC-associated diseases.
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Here we report a transcription factor decoy strategy for targeted activation of eight large silent polyketide synthase and non-ribosomal peptide synthetase gene clusters, ranging from 50 to 134 ...kilobases (kb) in multiple streptomycetes, and characterization of a novel oxazole family compound produced by a 98-kb biosynthetic gene cluster. Owing to its simplicity and ease of use, this strategy can be scaled up readily for discovery of natural products in streptomycetes.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract
Nonlinear gravitational evolution induces strong nonlinearities in the observed cosmological density fields, leading to positive off-diagonal correlations in the power spectrum covariance. ...This has caused the information saturation in the power spectrum, e.g., the neutrino mass constraints from the nonlinear power spectra are lower than their linear counterparts by a factor of ∼2 at
z
= 0. In this paper, we explore how nonlinear reconstruction methods improve the cosmological information from nonlinear cosmic fields. By applying nonlinear reconstruction to cold dark matter fields from the Quijote simulations, we find that nonlinear reconstruction can improve the constraints on cosmological parameters significantly, nearly reaching the linear theory limit. For neutrino mass, the result is only 12% lower than the linear power spectrum, i.e., the theoretical best result. This makes nonlinear reconstruction an efficient and useful method to extract neutrino information from current and upcoming galaxy surveys.
Particle swarm optimization (PSO) relies on its learning strategy to guide its search direction. Traditionally, each particle utilizes its historical best experience and its neighborhood's best ...experience through linear summation. Such a learning strategy is easy to use, but is inefficient when searching in complex problem spaces. Hence, designing learning strategies that can utilize previous search information (experience) more efficiently has become one of the most salient and active PSO research topics. In this paper, we proposes an orthogonal learning (OL) strategy for PSO to discover more useful information that lies in the above two experiences via orthogonal experimental design. We name this PSO as orthogonal learning particle swarm optimization (OLPSO). The OL strategy can guide particles to fly in better directions by constructing a much promising and efficient exemplar. The OL strategy can be applied to PSO with any topological structure. In this paper, it is applied to both global and local versions of PSO, yielding the OLPSO-G and OLPSO-L algorithms, respectively. This new learning strategy and the new algorithms are tested on a set of 16 benchmark functions, and are compared with other PSO algorithms and some state of the art evolutionary algorithms. The experimental results illustrate the effectiveness and efficiency of the proposed learning strategy and algorithms. The comparisons show that OLPSO significantly improves the performance of PSO, offering faster global convergence, higher solution quality, and stronger robustness.
Reduced haemodynamic response in the frontotemporal cortices of patients with major depressive disorder (MDD) has been demonstrated using functional near-infrared spectroscopy (fNIRS). Most notably, ...changes in cortical oxy-haemoglobin during a Japanese phonetic fluency task can differentiate psychiatric patients from healthy controls (HC). However, this paradigm has not been validated in the English language. Therefore, the present work aimed to distinguish patients with MDD from HCs, using haemodynamic response measured during an English letter fluency task. One hundred and five HCs and 105 patients with MDD took part in this study. NIRS signals during the verbal fluency task (VFT) was acquired using a 52-channel system, and changes in oxy-haemoglobin in the frontal and temporal regions were quantified. Depression severity, psychosocial functioning, pharmacotherapy and psychiatric history were noted. Patients with MDD had smaller changes in oxy-haemoglobin in the frontal and temporal cortices than HCs. In both regions of interest, oxy-haemoglobin was not associated with any of the clinical variables studied. 75.2% and 76.5% of patients with MDD were correctly classified using frontal and temporal region oxy-haemoglobin, respectively. Haemodynamic response measured by fNIRS during an English letter fluency task is a promising biomarker for MDD.
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