Intermolecular C-C/C-N σ-bond metathesis enabled by visible light.

Transition-metal-catalyzed double/triple bond metathesis reactions have been well-established due to the ability of transition-metal catalysts to readily interact with π bonds, facilitating the progression of the entire reaction. However, activating σ-bonds to induce σ-bond metathesis is more challenging due to the absence of π bonds and the high bond energy of σ bonds. In this study, we present a novel photo-induced approach that does not rely on transition metals or photosensitizers to drive C-C and C-N σ-bond metathesis reactions. This method enables the cross-coupling of tertiary amines with α-diketones via C-C and C-N single bonds cleavage and recombination. Notably, our protocol exhibits good compatibility with various functional groups in the absence of transition metals and external photosensitizers, resulting in the formation of aryl alkyl ketones and aromatic amides in good to high yields. To gain insights into the mechanism of this pathway, we conducted controlled experiments, intermediate trapping experiments, and DFT (Density Functional Theory) calculations. This comprehensive approach allowed us to elucidate the detailed mechanism underlying this transformative reaction.

Photochemically Driven Peptide Formation in Supersaturated Aerosol Droplets.

The condensation of amino acids into peptides plays a crucial role in protein synthesis and is thus essential for understanding the origins of life. However, the spontaneous formation of peptides from amino acids in bulk aqueous media is energetically unfavorable, posing a challenge for elucidating plausible abiotic mechanisms. In this study, we investigate the formation of amide bonds between amino acids within highly supersaturated aerosol droplets containing dicyandiamide (DCD), a cyanide derivative potentially present on primordial Earth. Metastable states, i.e. supersaturation, within individual micron-sized droplets are studied using both an optical trap and a linear quadrupole electrodynamic balance. When irradiated with intense visible light, amide bond formation is observed to occur and can be monitored using vibrational bands in Raman spectra. The reaction rate is found to be strongly influenced by droplet size and kinetic modelling suggests that it is driven by the photochemical product of a DCD self-reaction. Our results highlight the potential of atmospheric aerosol particles as reaction environments for peptide synthesis and have potential implications for the prebiotic chemistry of early Earth.

Unexpected response of terrestrial carbon sink to rural depopulation in China.

China is experiencing large-scale rural-urban migration and rapid urbanization, which have had significant impact on terrestrial carbon sink. However, the impact of rural-urban migration and its accompanying urban expansion on the carbon sink is unclear. Based on multisource remote sensing product data for 2000-2020, the soil microbial respiration equation, relative contribution rate, and threshold analysis, we explored the impact of rural depopulation on the carbon sink and its threshold. The results revealed that the proportion of the rural population in China decreased from 63.91 % in 2000 to 36.11 % in 2020. Human pressure decreased by 1.82% in rural depopulation areas, which promoted vegetation restoration in rural areas (+8.45 %) and increased the carbon sink capacity. The net primary productivity (NPP) and net ecosystem productivity (NEP) of the vegetation in the rural areas increased at rates of 2.95 g C m-2 yr-1 and 2.44 g C m-2 yr-1. Strong rural depopulation enhanced the carbon sequestration potential, and the NEP was 1.5 times higher in areas with sharp rural depopulation than in areas with mild rural depopulation. In addition, the rural depopulation was accompanied by urban expansion, and there was a positive correlation between the comprehensive urbanization level (CUL) and NEP in 75.29 % of urban areas. In the urban areas, the vegetation index increased by 88.42 %, and the urban green space partially compensated for the loss of carbon sink caused by urban expansion, with a growth rate of 4.96 g C m-2 yr-1. Changes in rural population have a nonlinear impact on the NEP. When the rural population exceeds 545.686 people/km2, an increase in the rural population will have a positive impact on the NEP. Our research shows that rural depopulation offers a potential opportunity to restore natural ecosystems and thus increase the carbon sequestration capacity.

Photosynthesis of CH3OH via oxygen-atom-grafting from CO2 to CH4 enabled by AuPd/GaN.

The direct co-conversion of methane and carbon dioxide into valuable chemicals has been a longstanding scientific pursuit for carbon neutrality and combating climate change. Herein, we present a photo-driven chemical process that reforms these two major greenhouse gases together to generate green methanol and CO, two high-valued industrial chemicals. Isotopic labeling and control experiments indicate an oxygen-atom-graft occurs, wherein CO2 transfers one O into the C-H bond of CH4 via photo-activated interfacial catalysis with AuPd nanoparticles supported on GaN. The photoexcited AuPd/GaN interface effectively orchestrates the CH4 oxidation and the CO2 reduction producing 13.66 mmol g-1 of CH3OH yield over 10 h. This design provides a solid scientific basis for the photo-driven oxygen-atom-grafting process to be further extended to visible light region.

Direct excitation strategy for deacylative couplings of ketones.

The homolysis of chemical bonds represents one of the most fundamental reactivities of excited molecules. Historically, it has been exploited to generate radicals under ultraviolet (UV) light irradiation. However, unlike most contemporary radical-generating mechanisms, the direct excitation to homolyze chemical bonds and produce aliphatic carbon-centered radicals under visible light remains rare, especially in metallaphotoredox cross couplings. Herein, we present our design of the dihydropyrimidoquinolinone (DHPQ) reagents derived from ketones, which can undergo formal deacylation and homolytic C-C bond cleavage to release alkyl radicals without external photocatalysts. Spectroscopic and computational analysis reveal unique optical and structural features of DHPQs, rationalizing their faster kinetics in alkyl radical generation than a structurally similar but visible-light transparent radical precursor. Such a capability allows DHPQ to facilitate a wide range of Ni-metallaphotoredox cross couplings with aryl, alkynyl and acyl halides. Other catalytic and non-catalyzed alkylative transformations of DHPQs are also feasible with various radical acceptors. We believe this work would be of broad interest, aiding the synthetic planning with simplified operation and expanding the synthetic reach of photocatalyst-free approaches in cutting-edge research.

PPh3-Promoted Direct Deoxygenation of Epoxides to Alkenes.

Deoxygenation of epoxides into alkenes is one of the most important strategies in organic synthesis, biomass conversions, and medicinal chemistry. Although metal-catalyzed direct deoxygenation provides one of the most commonly encountered protocols for the conversion of epoxides to alkenes, the requirement of expensive catalysts and extra reductants has largely limited their universal applicability. Herein, we report an efficient PPh3-promoted metal-free strategy for deoxygenation of epoxides to generate alkene derivatives. The success of deoxyalkenylation of epoxides bearing a wide range of functional groups to give terminal, 1,1-disubstituted, and 1,2-disubstituted alkenes manifests the powerfulness and versatility of this strategy. Moreover, gram-scale synthesis with excellent yield and modification of biologically active molecules exemplifies its generality and practicability.

Meiotic transcriptional reprogramming mediated by cell-cell communications in humans and mice revealed by scATAC-seq and scRNA-seq.

Meiosis is a highly complex process significantly influenced by transcriptional regulation. However, studies on the mechanisms that govern transcriptomic changes during meiosis, especially in prophase I, are limited. Here, we performed single-cell ATAC-seq of human testis tissues and observed reprogramming during the transition from zygotene to pachytene spermatocytes. This event, conserved in mice, involved the deactivation of genes associated with meiosis after reprogramming and the activation of those related to spermatogenesis before their functional onset. Furthermore, we identified 282 transcriptional regulators (TRs) that underwent activation or deactivation subsequent to this process. Evidence suggested that physical contact signals from Sertoli cells may regulate these TRs in spermatocytes, while secreted ENHO signals may alter metabolic patterns in these cells. Our results further indicated that defective transcriptional reprogramming may be associated with non-obstructive azoospermia (NOA). This study revealed the importance of both physical contact and secreted signals between Sertoli cells and germ cells in meiotic progression.

Anti-Markovnikov Hydroalkylation of Styrene Derivatives via Hydrazones Catalyzed by Ru-PNP Complex.

A well-defined Ru(II)-PNP complex demonstrated high activity in the anti-Markovnikov hydroalkylation of nonpolarized terminal alkenes via hydrazones. Hydrazone served as a carbanion equivalent to combine with the electrophilic alkene substrate upon activation by the ruthenium catalyst, forming a new C-C bond in a concerted pathway with N2 as the only theoretical byproduct. Experimental and computational studies suggested the existence of a push-pull interaction that activated the alkene for hydrazone addition and then deduced the mechanism.

IFI35 regulates non-canonical NF-κB signaling to maintain glioblastoma stem cells and recruit tumor-associated macrophages.

Glioblastoma (GBM) is the most aggressive malignant primary brain tumor characterized by a highly heterogeneous and immunosuppressive tumor microenvironment (TME). The symbiotic interactions between glioblastoma stem cells (GSCs) and tumor-associated macrophages (TAM) in the TME are critical for tumor progression. Here, we identified that IFI35, a transcriptional regulatory factor, plays both cell-intrinsic and cell-extrinsic roles in maintaining GSCs and the immunosuppressive TME. IFI35 induced non-canonical NF-kB signaling through proteasomal processing of p105 to the DNA-binding transcription factor p50, which heterodimerizes with RELB (RELB/p50), and activated cell chemotaxis in a cell-autonomous manner. Further, IFI35 induced recruitment and maintenance of M2-like TAMs in TME in a paracrine manner. Targeting IFI35 effectively suppressed in vivo tumor growth and prolonged survival of orthotopic xenograft-bearing mice. Collectively, these findings reveal the tumor-promoting functions of IFI35 and suggest that targeting IFI35 or its downstream effectors may provide effective approaches to improve GBM treatment.

Csp2-H functionalization of phenols: an effective access route to valuable materials via Csp2-C bond formation.

In the vast majority of top-selling pharmaceutical and industrial products, phenolic structural motifs are highly prevalent. Non-functionalized simple phenols serve as building blocks in the synthesis of value-added chemicals. It is worth mentioning that lignin, being the largest renewable biomass source of aromatic building blocks in nature, mainly consists of phenolic units, which enable the production of structurally diverse phenols. Given their remarkable applicability in the chemical value chain, many efforts have been devoted to increasing the molecular complexity of the phenolic scaffold. Among the key techniques, direct functionalization of Csp2-H is a powerful tool, enabling the construction of new Csp2-C bonds in an economical and atomic manner. Herein we present and summarize the large plethora of direct Csp2-H functionalization methods that enables scaffold diversification of simple, unprotected phenols, leading to the formation of new Csp2-C bonds. In this review article, we intend to summarize the contributions that appeared in the literature mainly in the last 5 years dealing with the functionalization of unprotected phenols, both catalytic and non-catalytic. Our goal is to highlight the key findings and the ongoing challenges in the stimulating and growing research dedicated to the development of new protocols for the valorization of phenols.

Dual role of nitroarenes as electrophiles and arylamine surrogates in Buchwald-Hartwig-type coupling for C-N bond construction.

One of the most widely utilized methods for the construction of C(sp2)-N bonds is the transition-metal-catalyzed cross-coupling of aryl halides/boronic acids with amines, known as Ullmann condensation, Buchwald-Hartwig amination, and Chan-Lam coupling. However, aryl halides/boronic acids often require multi-step preparation while generating a large amount of corrosive and toxic waste, making the reaction less attractive. Herein, we present an unprecedented method for the C(sp2)-N formation via Buchwald-Hartwig-type reactions using synthetically upstream nitroarenes as the sole starting materials, thus eliminating the need for arylhalides and pre-formed arylamines. A diverse range of symmetrical di- and triarylamines were obtained in a single step from nitroarenes, and more importantly, various unsymmetrical di- and triarylamines were also highly selectively synthesized in a one-pot/two-step process. Furthermore, the success of the scale-up experiments, the late-stage functionalization of a drug intermediate, and the rapid preparation of hole-transporting material TCTA showcased the utility and practicality of this protocol in synthetic chemistry. Mechanistic studies indicate that this transformation may proceed via an arylamine intermediate generated in situ from the reduction of nitroarenes, which is followed by a denitrative Buchwald-Hartwig-type reaction with another nitroarene to form a C-N bond.

The characterization of protein lactylation in relation to cardiac metabolic reprogramming in neonatal mouse hearts.

In mammals, the neonatal heart can regenerate upon injury within a short time after birth, while adults lose this ability. Metabolic reprogramming has been demonstrated to be critical for cardiomyocyte proliferation in the neonatal heart. Here, we reveal that cardiac metabolic reprogramming could be regulated by altering global protein lactylation. By performing 4D label-free proteomics and lysine lactylation (Kla) omics analyses in mouse hearts at postnatal days 1, 5, and 7, 2297 Kla sites from 980 proteins are identified, among which 1262 Kla sites from 409 proteins are quantified. Functional clustering analysis reveals that the proteins with altered Kla sites are mainly involved in metabolic processes. The expression and Kla levels of proteins in glycolysis show a positive correlation while a negative correlation in fatty acid oxidation. Furthermore, we verify the Kla levels of several differentially modified proteins, including ACAT1, ACADL, ACADVL, PFKM, PKM, and NPM1. Overall, our study reports a comprehensive Kla map in the neonatal mouse heart, which will help to understand the regulatory network of metabolic reprogramming and cardiac regeneration.

Visible-light-induced catalyst-free reductive coupling of aldehydes, ketones and imines with cyanopyridines.

This article introduces a reductive coupling driven by visible-light, facilitating the synthesis of pyridine-substituted alcohols and amines through the reaction of aldehydes, ketones and imines with cyanopyridines. Hantzsch esters serve as reductants in this process, eliminating the need for transition-metals or photosensitizers. The method demonstrates extensive compatibility and finds utility in the late-stage functionalization of both natural and pharmaceutical products, offering a sustainable pathway for the diversification of chemical compounds.

The research progress and research trends in acute coronary syndrome nursing: A review of visual analysis based on the Web of Science database.

Acute coronary syndrome (ACS) is one of the most common and severe forms of cardiovascular disease and has attracted worldwide attention with increased morbidity and mortality in recent years. There are few review studies in the field of its care in the form of bibliometric studies. We searched the Web of Science Core Collection database for articles and reviews in the area of ACS nursing for visual mapping analysis. Our objectives are to explore the hot topics and frontiers of research in the field of ACS nursing and to identify collaborative relationships between countries, institutions, and authors. This study will provide researchers with intuitive reference data for future in-depth studies of ACSs.

Ketone bodies promote epididymal white adipose expansion to alleviate liver steatosis in response to a ketogenic diet.

Liver can sense the nutrient status and send signals to other organs to regulate overall metabolic homoeostasis. Herein, we demonstrate that ketone bodies act as signals released from the liver that specifically determine the distribution of excess lipid in epididymal white adipose tissue (eWAT) when exposed to a ketogenic diet (KD). An acute KD can immediately result in excess lipid deposition in the liver. Subsequently, the liver sends the ketone body ß-hydroxybutyrate (BHB) to regulate white adipose expansion, including adipogenesis and lipogenesis, to alleviate hepatic lipid accumulation. When ketone bodies are depleted by deleting 3-hydroxy-3-methylglutaryl-CoA synthase 2 gene in the liver, the enhanced lipid deposition in eWAT but not in inguinal white adipose tissue is preferentially blocked, while lipid accumulation in liver is not alleviated. Mechanistically, ketone body BHB can significantly decrease lysine acetylation of peroxisome proliferator-activated receptor gamma in eWAT, causing enhanced activity of peroxisome proliferator-activated receptor gamma, the key adipogenic transcription factor. These observations suggest that the liver senses metabolic stress first and sends a corresponding signal, that is, ketone body BHB, to specifically promote eWAT expansion to adapt to metabolic challenges.

A General Platform for Visible Light Sulfonylation Reactions Enabled by Catalytic Triarylamine EDA Complexes.

Catalytic electron donor-acceptor (EDA) complexes have recently emerged as a powerful and sustainable alternative to iridium- and ruthenium-based photoredox synthetic methods. Yet, these complexes remain underexplored and reliant on the use of meticulously designed acceptors that require previous installation. Herein, we report a novel EDA complex employing tris(4-methoxyphenyl) amine as a catalytic donor for the sulfonylation of alkenes using inexpensive and readily available sulfonyl chlorides. Applying this operationally simple, visible-light-mediated general platform, we report both the redox-neutral and net-reductive functionalization of more than 60 substrates, encompassing vinylic or allylic sulfonylation, hydrosulfonylation, and sulfamoylation of activated and unactivated alkenes and alkynes.

ZrO2 Superhydrophobic Coating with an Excellent Corrosion Resistance and Stable Degradation Performance on Zr-Based Bulk Metallic Glass.

Photocatalysis is an energy-saving and high-efficiency green environmental technology. Because of its wide band gap and low light utilization, few studies have been conducted on ZrO2 used as a photocatalytic material. In this paper, a corrosion-resistant superhydrophobic ZrO2 coating was prepared on the surface of Zr-based bulk metallic glass by electrochemical etching. This coating not only showed a better corrosion resistance and easier collection, but also presented a stable degradation performance when combined with H2O2; these characteristics are necessary for photocatalysts to survive under harsh environments. This study provides a new direction for designing superhydrophobic surfaces on bulk metallic glass that possess a functional performance.