The combined effects of anthropogenic and biological CO
inputs may lead to more rapid acidification in coastal waters compared to the open ocean. It is less clear, however, how redox reactions would ...contribute to acidification. Here we report estuarine acidification dynamics based on oxygen, hydrogen sulfide (H
S), pH, dissolved inorganic carbon and total alkalinity data from the Chesapeake Bay, where anthropogenic nutrient inputs have led to eutrophication, hypoxia and anoxia, and low pH. We show that a pH minimum occurs in mid-depths where acids are generated as a result of H
S oxidation in waters mixed upward from the anoxic depths. Our analyses also suggest a large synergistic effect from river-ocean mixing, global and local atmospheric CO
uptake, and CO
and acid production from respiration and other redox reactions. Together they lead to a poor acid buffering capacity, severe acidification and increased carbonate mineral dissolution in the USA's largest estuary.The potential contribution of redox reactions to acidification in coastal waters is unclear. Here, using measurements from the Chesapeake Bay, the authors show that pH minimum occurs at mid-depths where acids are produced via hydrogen sulfide oxidation in waters mixed upward from anoxic depths.
Gastric cancer is a deadly disease and remains the third leading cause of cancer-related death worldwide. The 5-year overall survival rate of patients with early-stage localized gastric cancer is ...more than 60%, whereas that of patients with distant metastasis is less than 5%. Surgical resection is the best option for early-stage gastric cancer, while chemotherapy is mainly used in the middle and advanced stages of this disease, despite the frequently reported treatment failure due to chemotherapy resistance. Therefore, there is an unmet medical need for identifying new biomarkers for the early diagnosis and proper management of patients, to achieve the best response to treatment. Long non-coding RNAs (lncRNAs) in body fluids have attracted widespread attention as biomarkers for early screening, diagnosis, treatment, prognosis, and responses to drugs due to the high specificity and sensitivity. In the present review, we focus on the clinical potential of lncRNAs as biomarkers in liquid biopsies in the diagnosis and prognosis of gastric cancer. We also comprehensively discuss the roles of lncRNAs and their molecular mechanisms in gastric cancer chemoresistance as well as their potential as therapeutic targets for gastric cancer precision medicine.
Colloidal nanocrystals of fully inorganic cesium lead halide (CsPbX3, X = Cl, Br, I, or combinations thereof) perovskites have attracted much attention for photonic and optoelectronic applications. ...Herein, we demonstrate a facile room-temperature (e.g., 25 °C), ligand-mediated reprecipitation strategy for systematically manipulating the shape of CsPbX3 colloidal nanocrystals, such as spherical quantum dots, nanocubes, nanorods, and nanoplatelets. The colloidal spherical quantum dots of CsPbX3 were synthesized with photoluminescence (PL) quantum yield values up to >80%, and the corresponding PL emission peaks covering the visible range from 380 to 693 nm. Besides spherical quantum dots, the shape of CsPbX3 nanocrystals could be engineered into nanocubes, one-dimensional nanorods, and two-dimensional few-unit-cell-thick nanoplatelets with well-defined morphology by choosing different organic acid and amine ligands via the reprecipitation process. The shape-dependent PL decay lifetimes have been determined to be several to tens to hundreds of nanoseconds. Our method provides a facile and versatile route to rationally control the shape of the CsPbX3 perovskites nanocrystals, which will create opportunities for applications such as displays, lasing, light-emitting diodes, solar concentrators, and photon detection.
Microporous carbon sheets with precisely controlled thickness, narrow pores, short diffusion paths, high electrical conductive networks, and good wettability are synthesized using very low amounts of ...graphene sheets as a shape‐directing agent via an ionic liquid‐assisted surface coating method. When used as the electrode for supercapacitors, the sheets demonstrate excellent rate capability, good cycle stability, high specific capacitance, and high energy/power density.
The transport of sediment in regions with vegetation plays an important role in aquatic ecosystems and landform evolution in river deltas. In this study, flow parameters and suspended sediment ...concentration (SSC) within an emergent canopy with real plant morphology (Typha latifolia) were measured in a laboratory channel. T. latifolia is a common marsh species with multiple thin leaves emerging from a tight bundle (culm) at the bed. The observed equilibrium SSC profile differed significantly from a Rouse profile, the classic model for SSC over bare beds. The vertical distribution of SSC was nearly uniform in the culm region of the canopy, and decreased with height in the upper canopy region of distributed leaves. The profile of SSC reflected the vertically nonuniform turbulent diffusion, which arose from the plant morphology. A diffusivity model based on cylinder arrays was first validated with tracer data and then adapted to the T. latifolia morphology, providing a way to model turbulent diffusivity in marsh systems. The diffusivity model was successfully used within a random displacement model to predict the spatial evolution and equilibrium SSC profile within the T. latifolia canopy.
Key Points
Profiles of suspended sediment concentration (SSC) were measured in a model canopy of Typha latifolia
The vertical turbulent diffusivity depends on plant‐generated turbulence and morphology
A model to predict vertical diffusivity was developed, validated, and used to simulate the SSC with a random displacement model
Remote difunctionalization of unactivated alkenes is challenging but a highly attractive tactic to install two functional groups across long distances. Reported herein is the first remote ...difunctionalization of alkenes with CO2. This visible‐light photoredox catalysis strategy provides a facile method to synthesize a series of carboxylic acids bearing valuable fluorine‐ or phosphorus‐containing functional groups. Moreover, this versatile protocol shows mild reaction conditions, broad substrate scope, and good functional‐group tolerance. Based on DFT calculations, a radical adds to an unactivated alkene to smoothly form a new carbon radical, followed by a 1,5‐hydrogen atom‐transfer process, the rate‐limiting step, generating a more stable benzylic radical. The reduction of the benzylic radicals by an IrII species generates the corresponding benzylic carbanions as the key intermediates, which further undergo nucleophilic attack with CO2 to generate carboxylates.
Reported is the first remote difunctionalization of unactivated alkenes with CO2 by visible‐light photoredox catalysis. Mechanistic studies indicate that a 1,5‐hydrogen atom‐transfer process is the rate‐limiting step and reduction of radical intermediates generates the corresponding carbanions. Other electrophiles, including aldehydes, ketones, and benzylic bromides, are also applicable in this process, demonstrating a general strategy for redox‐neutral remote difunctionalization of unactivated alkenes.
Context:
Vitamin D deficiency is common in pregnant women. Nevertheless, the association between maternal vitamin D status during pregnancy and the risk of having small for gestational age (SGA) and ...low birth weight (LBW) infants is uncertain.
Objective:
The objective of this study was to investigate whether there is a correlation between maternal vitamin D deficiency during pregnancy and the risk of having SGA and LBW infants in a Chinese population.
Design and Participants:
This was a population-based birth cohort study that recruited 3658 eligible mother-and-singleton-offspring pairs.
Main Outcome Measures:
Serum 25-hydroxyvitamin D was measured by RIA. The rate and relative risk (RR) for SGA and LBW infants were calculated among subjects with vitamin D deficiency and insufficiency during pregnancy.
Results:
There was a positive correlation between maternal serum 25-hydroxyvitamin D level and offspring birth weight (r = 0.477; P < .001). Further analysis showed that 4.98% of neonates were LBW infants among the subjects with vitamin D deficiency (RR, 12.00; 95% confidence interval CI, 4.37, 33.00) and 1.32% among the subjects with vitamin D insufficiency (RR, 3.18; 95% CI, 1.07, 9.48). After adjustment for confounders, the RR for LBW infants was 12.31 (95% CI, 4.47, 33.89) among subjects with vitamin D deficiency and 3.15 (95% CI, 1.06, 9.39) among subjects with vitamin D insufficiency. Moreover, 16.01% of neonates were SGA infants among subjects with vitamin D deficiency (RR, 5.72; 95% CI, 3.80, 8.59) and 5.59% among subjects with vitamin D insufficiency (RR, 1.99; 95% CI, 1.27, 3.13). After adjustment for confounders, the RR for SGA infants was 6.47 (95% CI, 4.30, 9.75) among subjects with vitamin D deficiency and 2.01 (95% CI, 1.28, 3.16) among subjects with vitamin D insufficiency.
Conclusion:
Maternal vitamin D deficiency during pregnancy elevates the risk of SGA and LBW infants in a Chinese population.
Both furan and 1,4‐dihydropyridine (1,4‐DHP) are key structural motifs in pharmaceuticals. Herein, we report the synthesis of 4‐(furan‐2‐ylmethyl)‐1,4‐dihydropyridines from pyridiniums and furfural ...derivatives under NHC catalysis. This reaction involves the generation of NHC‐bounded trienolates from furfural derivatives and following addition to the C‐4 position of N‐aryl pyridinium salts. This protocol features good yields (41–99%), and high levels of regioselectivity (>20:1 for all cases).
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