Clayey silt reservoirs bearing natural gas hydrates (NGH) are considered to be the hydrate-bearing reservoirs that boast the highest reserves but tend to be the most difficult to exploit. They are ...proved to be exploitable by the first NGH production test conducted in the South China Sea in 2017. Based on the understanding of the first production test, the China Geological Survey determined the optimal target NGH reservoirs for production test and conducted a detailed assessment, numerical and experimental simulation, and onshore testing of the reservoirs. After that, it conducted the second offshore NGH production test in 1225 m deep Shenhu Area, South China Sea (also referred to as the second production test) from October 2019 to April 2020. During the second production test, a series of technical challenges of drilling horizontal wells in shallow soft strata in deep sea were met, including wellhead stability, directional drilling of a horizontal well, reservoir stimulation and sand control, and accurate depressurization. As a result, 30 days of continuous gas production was achieved, with a cumulative gas production of 86.14 ×104 m3. Thus, the average daily gas production is 2.87 ×104 m3, which is 5.57 times as much as that obtained in the first production test. Therefore, both the cumulative gas production and the daily gas production were highly improved compared to the first production test. As indicated by the monitoring results of the second production test, there was no anomaly in methane content in the seafloor, seawater, and atmosphere throughout the whole production test. This successful production test further indicates that safe and effective NGH exploitation is feasible in clayey silt NGH reservoirs. The industrialization of hydrates consists of five stages in general, namely theoretical research and simulation experiments, exploratory production test, experimental production test, productive production test, and commercial production. The second production test serves as an important step from the exploratory production test to experimental production test.
Herein, we report a concise and divergent synthesis of the complex hasubanan alkaloids metaphanine and oxoepistephamiersine from commercially available and inexpensive cyclohexanedione monoethylene ...acetal. Our synthesis features a palladium‐catalyzed cascade cyclization reaction to set the tricyclic carbon framework of the desired molecules, a regioselective Baeyer–Villiger oxidation followed by a MeNH2 triggered skeletal reorganization cascade to construct the benzannulated aza4.4.3propellane, and a strategically late‐stage regio‐/diastereoselective oxidative annulation of sp3 C−H bond to form the challenging THF ring system and hemiketal moiety in a single step. In addition, a highly enantioselective alkylation of cyclohexanedione monoethylene acetal paved the way for the asymmetric synthesis of target molecular.
Two complex hasubanan alkaloids were synthesized from inexpensive cyclohexanedione monoethylene acetal by a divergent route featuring a palladium‐catalyzed cascade cyclization. Regioselective Baeyer–Villiger oxidation followed by MeNH2‐triggered skeletal reorganization formed the benzannulated aza4.4.3propellane, and late‐stage regio‐ and diastereoselective oxidative annulation of a sp3 C−H bond formed the challenging tetrahydrofuran ring system.
A palladium catalyzed reductive aminocarbonylation of benzylic ammonium triflates with nitroarenes for the synthesis of phenylacetamides was developed. Using Pd(acac)2/DPPF catalyst system, a range ...of different substituted phenylacetamides were prepared in moderate to good yields from benzylic ammonium triflates and nitroarenes through Csp3−N bond cleavage. A variety of alkyl, aryl, and halide substituents on both substrates can be used, and many useful functional groups can be tolerated.
Secondary metabolites that have the same biological origin must share some relationship in their biosynthesis. Exploring this relationship has always been a significant task for synthetic biologists. ...However, from the perspective of synthetic chemists, it is equally important to propose, prove, or refute potential biosynthetic pathways in order to elucidate and understand the biosynthesis of homologous secondary metabolites. In this study, driven by the high structural similarity between the homologous Ganoderma meroterpenoids cochlearol B and ganocin B, two chemically synthetic strategies were designed and investigated sequentially for the synthesis of cochlearol B from ganocin B. These strategies include intramolecular metal‐catalyzed hydrogen atom transfer (MHAT) and intramolecular photochemical 2+2 cycloaddition. The aim was to reveal their potential biosynthetic conversion relationship using chemical synthesis methods. As a result, a highly efficient total synthesis of cochlearol B, cochlearol T, cochlearol F, as well as the formal total synthesis of ganocins A–B, and ganocochlearins C–D, has been achieved. Additionally, a novel synthetic approach for the synthesis of 6,6‐disubstituted 6H‐dibenzob,dpyran and its analogues has been developed through palladium(II)‐catalyzed Wacker‐type/cross‐coupling cascade reactions.
In this study, driven by the high structural similarity between the homologous Ganoderma meroterpenoids cochlearol B and ganocin B, two chemically synthetic strategies were designed and investigated sequentially for the synthesis of cochlearol B from ganocin B. These strategies include intramolecular metal‐catalyzed hydrogen atom transfer (MHAT) and intramolecular photochemical 2+2 cycloaddition. The aim was to reveal their potential biosynthetic conversion relationship using chemical synthesis methods. As a result, a highly efficient total synthesis of cochlearol B, cochlearol T, cochlearol F, as well as the formal total synthesis of ganocins A–B, and ganocochlearins C–D, has been achieved. Additionally, a novel synthetic approach for the synthesis of 6,6‐disubstituted 6H‐dibenzob,dpyran and its analogues has been developed through palladium(II)‐catalyzed Wacker‐type/cross‐coupling cascade reactions.
Single-cell imaging is essential for elucidating the biological mechanism of cell function because it accurately reveals the heterogeneity among cells. The electrochemiluminescence (ECL) microscopy ...technique has been considered a powerful tool to study cells because of its high throughput and zero cellular background light. However, since cells are immobilized on the electrode surface, the steric hindrance and the insulation from the cells make it difficult to obtain a luminous cell ECL image. To solve this problem, direct ECL imaging of a single cell was investigated and achieved on chitosan and nano-TiO2 modified fluoride-doped tin oxide conductive glass (FTO/TiO2/CS). The permeable chitosan film is not only favorable for cell immobilization but also increases the space between the bottom of cells and the electrode; thus, more ECL reagent can exist below the cells compared with the cells on a bare electrode, which guarantees the high sensitivity of quantitative analysis. The modification of nano-TiO2 strengthens the ECL visual signal in luminol solution and effectively improves the signal-to-noise ratio. The light intensity is correlated with the H2O2 concentration on FTO/TiO2/CS, which can be applied to analyze the H2O2 released from cells at the single-cell level. As far as we know, this is the first work to achieve cell ECL imaging without the steric hindrance effect of the cell, and it expands the applications of a modified electrode in visualization study.
In this work, a potential-resolved electrochemiluminescence (ECL) method is developed and used for the apoptosis diagnosis at the single-cell level. The apoptosis of cells usually induces the ...decreasing expression of epidermal growth factor receptor (EGFR) and promotes phosphatidylserine (PS) eversion on the cell membrane. Here, Au@L012 and g-C3N4 as ECL probes are functionalized with epidermal growth factor (EGF) and peptide (PSBP) to recognize the EGFR and PS on the cell surface, respectively, showing two well-separated ECL signals during a potential scanning. Experimental results reveal that the relative ECL change of g-C3N4 and Au@L012 correlates with the degree of apoptosis, which provides an accurate way to investigate apoptosis without interference that solely changes EGFR or PS. With a homemade ECL microscopy, we simultaneously evaluate the EGFR and PS expression of abundant individual cells and, therefore, achieve the visualization analysis of the apoptosis rate for normal and cancer cell samples. This strategy contributes to visually studying tumor markers and pushing the application of ECL imaging for the disease diagnosis at the single-cell level.
A potassium carbonate promoted tandem oxy-Michael addition/cyclization of α,β-unsaturated carbonyl compounds with naphthol derivatives for the synthesis of 2-substituted naphthopyrans was developed. ...Using the readily available, inexpensive potassium carbonate as the promoter, a range of different substituted naphthopyrans were prepared.
A palladium-catalyzed intramolecular Heck/aminocarbonylation of alkene-tethered iodobenzenes with nitro compounds has been developed for the synthesis of carbamoyl-substituted benzoheterocycles. ...Using Mo(CO)6 as a solid CO source, no external reductant or additives were needed in this procedure. Both nitroarenes and nitroalkanes were well tolerated. A range of carbamoyl-substituted dihydrobenzofurans and indolines were prepared in moderate to high yields.
Enantioselective cross-electrophile reactions remain a challenging subject in metal catalysis, and with respect to data, studies have mainly focused on stereoconvergent reactions of racemic alkyl ...electrophiles. Here, we report an enantioselective cross-electrophile aryl-alkenylation reaction of unactivated alkenes. This method provides access to a number of biologically important chiral molecules such as dihydrobenzofurans, indolines, and indanes. The incorporated alkenyl group is suitable for further reactions that can lead to an increase in molecular diversity and complexity. The reaction proceeds under mild conditions at room temperature, and an easily accessible chiral pyrox ligand is used to afford products with high enantioselectivity. The synthetic utility of this method is demonstrated by enabling the modification of complex molecules such as peptides, indometacin, and steroids.
The granulosa cells (GCs) of birds are essential for the reproduction and maintenance of populations in nature. Atrazine (ATR) is a potent endocrine disruptor that can interfere with reproductive ...function in females and Diaminochlorotriazine (DACT) is the primary metabolite of ATR in the organism. Melatonin (MT) is an endogenous hormone with antioxidant properties that plays a crucial role in development of animal germ cells. However, how ATR causes mitochondrial dysfunction, abnormal secretion of steroid hormones, and whether MT prevents ATR-induced female reproductive toxicity remains unclear. Thus, the purpose of this study is to investigate the protective effect of MT against ATR-induced female reproduction. In the present study, the GCs of quail were divided into 6 groups, as follows: C (Serum-free medium), MT (10 µM MT), A250 (250 µM ATR), MA250 (10 µM MT+250 µM ATR), D200 (200 µM DACT) and MD200 (10 µM MT+200 µM DACT), and were cultured for 24 h. The results revealed that ATR prevented GCs proliferation and decreased cell differentiation. ATR caused oxidative damage and mitochondrial dysfunction, leading to disruption of steroid synthesis, which posed a severe risk to GC's function. However, MT supplements reversed these changes. Mechanistically, our study exhibited that the ROS/SIRT1/STAR axis as a target for MT to ameliorate ATR-induced mitochondrial dysfunction and steroid disorders in GCs, which provides new insights into the role of MT in ATR-induced reproductive capacity and species conservation in birds.
