Abstract
The present study investigates the interannual variability of the tropical Indian Ocean (IO) based on the transfer routes of wave energy in a set of 61-yr hindcast experiments using a linear ...ocean model. To understand the basic feature of the IO dipole mode, this paper focuses on the 1994 pure positive event. Two sets of westward transfer episodes in the energy flux associated with Rossby waves (RWs) are identified along the equator during 1994. One set represents the same phase speed as the linear theory of equatorial RWs, while the other set is slightly slower than the theoretical phase speed. The first set originates from the reflection of equatorial Kelvin waves at the eastern boundary of the IO. On the other hand, the second set is found to be associated with off-equatorial RWs generated by southeasterly winds in the southeastern IO, which may account for the appearance of the slower group velocity. A combined empirical orthogonal function (EOF) analysis of energy-flux streamfunction and potential reveals the intense westward signals of energy flux are attributed to off-equatorial RWs associated with predominant wind input in the southeastern IO corresponding to the positive IO dipole event.
Significance Statement
The present study gains a new insight into the mechanism of the Indian Ocean dipole events using a new diagnostic scheme for wave energy based on 61-yr hindcast experiments. The results have shown the existence of two sets of westward transfer of wave energy at the equator during 1994. One set of westward signals shows the same group velocity with theoretical equatorial Rossby waves that appear reasonably along the equator. The other set of westward signals at the equator represents a slightly slower group velocity than the theoretical equatorial Rossby waves, which is associated with abnormally extended southeasterly winds during the Indian Ocean dipole event.
Multistimuli‐responsive chromism was observed for vinylene‐linked bisflavin 1 a with an extended π‐conjugated platform. The yellow emission of a dilute solution of 1 a in CHCl3 (0.2 mM) observed at ...298 K under UV excitation was changed to orange or red emission upon (1) an increase of concentration, (2) a decrease of temperature, and (3) variation of the solvent. This is in contrast to the almost non stimuli‐responsive chromism of the N‐methylated bisflavin analogue 1 b and monoflavin 2 a. Mechanistic investigation by 1H NMR analysis under various conditions revealed that the extended π‐conjugation platform and imide moiety of 1 a generate controllability in the formation of lower‐ and higher‐ordered aggregates, which induce variation of the emission color upon change. Bisflavin 1 a also exhibited redox‐induced chromism, where the orange emission of 1 a was quenched by the addition of hydrazine under anaerobic conditions, and changed back to the original emission upon subsequent bubbling of O2 gas.
Bisflavin 1 a exhibits multi‐stimuli responsive chromism: The fluorescent color of 1 a can be controlled upon variation of concentration, temperature, solvent, and additives based on the specific aggregation and redox properties arising from highly π‐conjugated platform. The utility is demonstrated by multi‐colored drawing with 1 a inks with various concentrations.
Sulfate is traditionally considered to have retrograde solubility in aqueous solutions. However, our recent hydrothermal diamond-anvil cell (HDAC) experiments have shown that the solubility of Na2SO4 ...changes from retrograde to prograde in the presence of silica, leading to the formation of sulfate-rich solutions at high temperatures, in line with observations on natural geofluids. In this study, we use synthetic inclusions of fused silica capillary capsules containing saturated Na2SO4 solutions and Na2SO4 crystals to quantitatively investigate the solubility of Na2SO4 at different temperatures in the Na2SO4-SiO2-H2O system. Sulfate concentrations were measured using Raman spectroscopy and calibrated using Cs2SO4 solutions with known concentrations. The solubility of crystalline Na2SO4 dropped slightly when heated from 50 to 225°C and dramatically from 225 to 313°C. At 313°C, the Na2SO4 crystals began to melt, forming immiscible sulfate melt coexisting with the aqueous solution, with or without solid Na2SO4. With the formation of sulfate melt, the solubility of Na2SO4 was reversed to prograde (i.e., solubility increased considerably with increasing temperatures). The solubility of Na2SO4 in the measured solution was significantly higher than that predicted in the absence of SiO2 over the entire temperature range (except for temperatures around 313°C). This indicates that the presence of SiO2 greatly changes the dissolution behavior of Na2SO4, which may be caused by the formation of a sulfate-silicate intermediates such as Si(OH)4SO42-. Considering that most crustal fluids are silica-saturated, the solubility curve of Na2SO4 obtained in this study can better reflect the characteristics of geofluids when compared to that of Na2SO4-H2O binary system. At temperatures of 313-425°C, the solubility of Na2SO4 increases with temperature following the function Csulfate=-3173.7/T to +5.9301, where Csulfate and T represent the solubility of Na2SO4 in mol/kg H2O and temperature in Kelvin, respectively. As an application, this temperature-solubility relationship can be used to evaluate the sulfate contents in fluid inclusions that contain sulfate daughter minerals, based on the temperature of sulfate disappearance obtained from microthermometric analysis. The sulfate concentrations of the ore-forming fluids of the giant Maoniuping carbonatite-related rare earth element (REE) deposit (southwest China) were calculated to be 4.67-4.81 m (mol/kg H2O). These sulfate concentrations were then used as internal standards to calibrate the previously reported semi-quantitative results of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis of REE-forming stage fluid inclusions at this deposit. The calculated Ce concentrations in the REE-mineralizing fluid range from 0.42 to 0.49 wt%. The high fluid REE contents suggest that the sulfate-rich fluids are ideal solvents for REE transport. A mass-balance calculation was carried out to evaluate the minimal volume of carbonatite melt that was required for the formation of the giant Maoniuping REE deposit. The result indicates that the carbonatite dikes in the mining area are enough to provide the required fluids and metals, and thus a deep-seated magma chamber is not necessary for ore formation.
The Ctp1 protein in Schizosaccharomyces pombe is essential for DNA double-strand break (DSB) repair by homologous recombination. Fission yeast Ctp1 and its budding yeast (Sae2) and human (CtIP) ...homologs control Mre11–Rad50–Nbs1 nuclease complex activity and harbor DNA-binding and -bridging activities. However, the molecular basis for Ctp1–DNA transactions remains undefined. Here, we report atomic force microscopy (AFM) imaging of S. pombe Ctp1–DNA complexes revealing that Ctp1 polymerizes on dsDNA molecules and forms synaptic filaments that bridge two dsDNA strands. We observed that Ctp1 DNA filaments are typified by an average filament length of ∼180 bp of dsDNA and a Ctp1 tetramer footprint of ∼15 bp. Biochemical results characterizing Ctp1 variants with impaired DNA-binding or -bridging properties were consistent with Ctp1-mediated DNA bridging requiring the intact and correctly folded Ctp1 tetramer. Furthermore, mutations altering Ctp1 oligomerization and DNA bridging in vitro conferred cell sensitivity to DSB-producing agents. Together, these results support an important role for Ctp1-regulated DNA strand coordination required for DNA DSB repair in S. pombe.
Hydrothermal H2S is an important energy source for hydrothermal ecosystems. However, it is difficult to obtain accurate hydrogen sulfide concentrations in high‐temperature hydrothermal fluids because ...they are highly susceptible to oxidation and compositional variability with mixing. In this study, a new in situ approach for measuring H2S, HS− and pH in hydrothermal fluids was developed and applied to the detections of Okinawa Trough hydrothermal activities. The in situ total H2S concentrations in the Jade and Biwako fluids were determined to be 31.4 and 76.7 mmol/kg, respectively. The in situ measured pH of the Jade fluids was determined to be 6.3, which has exceeded that of a neutral fluid at a specific temperature and pressure, indicating that the pH of Jade fluids is weakly alkaline. The pH transition of hydrothermal fluids from alkaline to acidic may be attributed to the thermal decomposition of organic matter and sulfide precipitation.
Plain Language Summary
Hydrogen sulfide is one of the important gases released from hydrothermal systems, but it is difficult to measure its concentration accurately because it is highly susceptible to oxidation and compositional variability with mixing. The in situ pH of hydrothermal fluids is also a challenging parameter to obtain, as it is significantly affected by factors such as temperature variation and mineral precipitation. Traditional methods of sampling followed by laboratory analysis inevitably result in changes in hydrogen sulfide concentration and pH. Furthermore, conventional chemical sensors and pH electrodes cannot withstand the high‐temperature extreme environment of hydrothermal vents, making it impossible to directly obtain these parameters at the high‐temperature vent orifice. Here, we developed a new method for in situ measurement of the H2S‐HS− ionization equilibrium system based on Raman spectroscopy and used it to determine the H2S concentration and in situ pH of hydrothermal fluids in the Okinawa Trough.
Key Points
The first in situ measured pH of high‐temperature hydrothermal vent fluids at arc‐back arc basins was reported
A new approach to obtain in situ H2S/HS− concentration and in situ pH of high temperature hydrothermal vent fluids was established
The pH transition of hydrothermal fluids from alkaline to acidic should attributes to the precipitation of sulfide minerals
The trade-offs between sexual reproduction and clonal propagation are of great significance in terms of ecology and evolution for clonal plants, and they vary with environmental change. Nitrogen (N) ...deposition can increase litter accumulation in grassland and promote litter decomposition and consequently increase nutrient availability. However, the response of plant reproduction to N and litter addition in grasslands remains unclear. We examined the combined effects of N addition and litter manipulation (i.e. initial litter, removal, addition) on sexual reproduction and clonal propagation of a perennial clonal grass,
Leymus chinensis
, at the population (total number) and individual (number per ramet) levels in an 11-year field experiment. Nitrogen addition and litter additionally decreased spike and seed number at the population level, and N addition reduced those at the individual level. Nitrogen addition and litter interactively affected bud number at the two levels, and N addition decreased bud number in the litter removal treatments and increased that in the litter addition treatments. The increased soil available N, rather than light and soil water content, explained the change in sexual reproduction and clonal propagation. The positive effects of litter addition on bud number in the treatments with N addition, suggested that the N deposition increased litter accumulation could intensify clonal propagation of perennial grasses and increase their dominance in grasslands. Grassland management that reduces litter accumulation, such as grazing and mowing, can therefore, help alleviate the negative effects of N deposition on plant diversity through decreasing clonal propagation of the dominant species.
Diabetic retinopathy (DR) is the most frequent microvascular complication of diabetes mellitus, however, its underlying biological mechanisms remain poorly understood. We examined single nucleotide ...polymorphisms linked to 486 blood metabolites through extensive genome-wide association studies conducted on individuals of European ancestry. The FinnGen Biobank database served as a reference to define DR. Two-sample MR analysis was conducted to reveal the association between the levels of genetically predicted circulating metabolites and the susceptibility to DR. To validate the robustness of the obtained findings, sensitivity analyses with weighted median, weighted mode, and MR-Egger were conducted. 1-oleoylglycerophosphoethanolamine (odds ratio OR (OR per one standard deviation SD increase) = 0.414; 95% confidence interval CI 0.292-0.587; P = 7.613E-07, P
= 6.849E-06), pyroglutamine (OR per one SD increase = 0.414; 95% confidence interval CI 0.292-0.587; P = 8.31E-04, P
= 0.007), phenyllactate (PLA) (OR per one SD increase = 0.591; 95% confidence interval CI 0.418-0.836; P = 0.003, P
= 0.026), metoprolol acid metabolite (OR per one SD increase = 0.978; 95% confidence interval CI 0.962-0.993; P = 0.005, P
= 0.042), 10-undecenoate (OR per one SD increase = 0.788; 95% confidence interval CI 0.667-0.932; P = 0.005, P
= 0.049), erythritol (OR per one SD increase = 0.691; 95% confidence interval CI 0.513-0.932; P = 0.015, P
= 0.034), 1-stearoylglycerophosphoethanolamine (OR per one SD increase = 0.636; 95% confidence interval CI 0.431-0.937; P = 0.022, P
= 0.099), 1-arachidonoylglycerophosphoethanolamine (OR per one SD increase = 0.636; 95% confidence interval CI 0.431-0.937; P = 0.030, P
= 0.099) showed a significant causal relationship with DR and could have protective effects. stachydrine (OR per one SD increase = 1.146; 95% confidence interval CI 1.066-1.233; P = 2.270E-04, P
= 0.002), butyrylcarnitine (OR per one SD increase = 1.117; 95% confidence interval CI 1.023-1.219; P = 0.014, P
= 0.062), 5-oxoproline (OR per one SD increase = 1.569; 95% confidence interval CI 1.056-2.335; P = 0.026, P
= 0.082), and kynurenine (OR = 1.623; 95% CI 1.042-2.526; P = 0.041, P
= 0.097) were significantly associated with an increased risk of DR. This study identified metabolites have the potential to be considered prospective compounds for investigating the underlying mechanisms of DR and for selecting appropriate drug targets.
Purpose
In the prediction of COVID-19 disease progression, a clear illustration and early determination of an area that will be affected by pneumonia remain great challenges. In this study, we aimed ...to predict and visualize the progression of lung lesions in COVID-19 patients in the early stage of illness by using chest CT.
Methods
COVID-19 patients who underwent three chest CT scans in the progressive phase were retrospectively enrolled. An extended CT ventilation imaging (CTVI) method was proposed in this work that was adapted to use two chest CT scans acquired on different days, and then lung ventilation maps were generated. The prediction maps were obtained according to the fractional ventilation values, which were related to pulmonary regional function and tissue property changes. The third CT scan was used to validate whether the prediction maps could be used to distinguish healthy regions and potential lesions.
Results
A total of 30 patients (mean age ± SD, 43 ± 10 years, 19 females, and 2–12 days between the second and third CT scans) were included in this study. The predicted lesion locations and sizes were almost the same as the true ones visualized in third CT scan. Quantitatively, the predicted lesion volumes and true lesion volumes showed both a good Pearson correlation (R
2
= 0.80;
P
< 0.001) and good consistency in the Bland–Altman plot (mean bias = 0.04 cm
3
). Regarding the enlargements of the existing lesions, prediction results also exhibited a good Pearson correlation (R
2
= 0.76;
P
< 0.001) with true lesion enlargements.
Conclusion
The present findings demonstrated that the extended CTVI method could accurately predict and visualize the progression of lung lesions in COVID-19 patients in the early stage of illness, which is helpful for physicians to predetermine the severity of COVID-19 pneumonia and make effective treatment plans in advance.
The epigenetic inheritance of DNA methylation requires UHRF1, a histone- and DNA-binding RING E3 ubiquitin ligase that recruits DNMT1 to sites of newly replicated DNA through ubiquitylation of ...histone H3. UHRF1 binds DNA with selectivity towards hemi-methylated CpGs (HeDNA); however, the contribution of HeDNA sensing to UHRF1 function remains elusive. Here, we reveal that the interaction of UHRF1 with HeDNA is required for DNA methylation but is dispensable for chromatin interaction, which is governed by reciprocal positive cooperativity between the UHRF1 histone- and DNA-binding domains. HeDNA recognition activates UHRF1 ubiquitylation towards multiple lysines on the H3 tail adjacent to the UHRF1 histone-binding site. Collectively, our studies are the first demonstrations of a DNA-protein interaction and an epigenetic modification directly regulating E3 ubiquitin ligase activity. They also define an orchestrated epigenetic control mechanism involving modifications both to histones and DNA that facilitate UHRF1 chromatin targeting, H3 ubiquitylation, and DNA methylation inheritance.
Heavy metals often coexist in contaminated environmental media, and competition between heavy metals for adsorption sites influences the absorption capacity of biochar. In this study, the adsorption ...mechanism of pyrolytically modified wood ear mushroom sticks (250, 450, and 650 °C) as a new bio-adsorbent for single-ion and mixed-ion solutions Cd2+ and Pb2+ Biochar adsorption experiments showed that the adsorption abilities of Cd2+ and Pb2+ increased with increasing WMBC (wood ear mushroom sticks biochar) pyrolysis temperature. According to the Langmuir model, the maximum adsorption capacity of Cd2+ and Pb2+increased with higher pyrolysis temperature, being 29.84, 39.08, 46.16 mg·g−1and 124.3, 186.8, 234.2 mg·g−1, respectively for three different pyrolysis temperatures 250, 450, and 650 °C. WMBC exhibited a stronger adsorption ability for Pb2+ than for Cd2+. Competition between the two heavy metals severely inhibited the adsorption of Cd2+. Based on X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and Fourier transform infrared spectroscopy (FTIR) analyses, the dominant interaction mechanisms were determined to be complexation, ion exchange, precipitation, and C–π interaction. The results suggest WMBC shows promise as a novel, cheap, and effective adsorbent that can be used to remove both Cd2+ and Pb2+ pollutants from environmental media.
Display omitted
•WMBC as a novel adsorbent was prepared from a wood ear mushroom sticks.•WMBC at 650 °C exhibited good adsorption affinity for Cd2+ and Pb2+.•Pb2+ would inhibit Cd2+ adsorption in mixed adsorption.•Freundlich isotherm fitted the experimental data for all solution temperatures.•Pb is easily adsorbed by complexation and sorption reactions than Cd.
PDF
