Persistent organic pollutants (POPs) are ubiquitous and bioaccumulative, posing potential and long-term threats to human health and the ecological environment. Quantitative structure–activity ...relationship (QSAR) studies play a guiding role in analyzing the toxicity and environmental fate of different organic pollutants. In the current work, five molecular descriptors are utilized to construct QSAR models for predicting the mean and maximum air half-lives of POPs, including specifically the energy of the highest occupied molecular orbital (HOMO_Energy_DMol3), a component of the dipole moment along the z-axis (Dipole_Z), fragment contribution to SAscore (SAscore_Fragments), subgraph counts (SC_3_P), and structural information content (SIC). The QSAR models were achieved through the application of three machine learning methods: partial least squares (PLS), multiple linear regression (MLR), and genetic function approximation (GFA). The determination coefficients (R2) and relative errors (RE) for the mean air half-life of each model are 0.916 and 3.489% (PLS), 0.939 and 5.048% (MLR), 0.938 and 5.131% (GFA), respectively. Similarly, the determination coefficients (R2) and RE for the maximum air half-life of each model are 0.915 and 5.629% (PLS), 0.940 and 10.090% (MLR), 0.939 and 11.172% (GFA), respectively. Furthermore, the mechanisms that elucidate the significant factors impacting the air half-lives of POPs have been explored. The three regression models show good predictive and extrapolation abilities for POPs within the application domain.
Magnetosonic (MS) waves are dominant plasma waves causing severe Martian ionospheric erosion. They are generally considered to originate upstream of Martian bow shock with frequencies near the ...upstream proton gyrofrequency. However, whether MS waves can be locally excited lacks theoretical analysis. Here we present an event of MS waves with frequencies above and closely related to the local proton gyrofrequency in the Martian ionosphere. Concurrently, ring beam hot proton distributions are observed due to the penetration of magnetosheath protons. By employing the observed plasma and magnetic field data, the calculated linear growth rates for MS waves agree well with the observed wave power spectra, demonstrating that they can be locally excited by unstable ring beam hot protons at Mars. Our results could be of great help in understanding the excitation of MS waves in a heavy ion‐rich environment around unmagnetized planets.
Plain Language Summary
Magnetosonic (MS) wave is one of the most important plasma waves contributing to the Martian atmospheric loss. They are generally considered to originate upstream of the Martian bow shock. Recent observations at Mars have shown that some MS waves with frequencies near the local proton gyrofrequency were accompanied by ring/shell‐like hot proton distributions. However, whether these waves can be locally excited by such protons lacks the support of the theoretical analysis. In this letter, on the basis of linear instability analysis, we show that MS waves with frequencies well above the local proton gyrofrequency can be locally excited by unstable ring beam hot protons in the Martian ionosphere. These results advance our knowledge of the MS wave excitation in a heavy ion‐rich environment around planets without an intrinsic magnetic field.
Key Points
Magnetosonic waves above the local proton gyrofrequency are observed in the Martian ionosphere
Ring beam hot proton distribution associated with magnetosonic waves is formed by the penetration of solar wind protons simultaneously
Magnetosonic waves are locally generated by the ring beam hot protons
Background:
Selective reporting has important value in antibiotic management. The purpose of this study was to explore the impact of AST selective reporting on prescribing behavior, so as to provide ...evidence for the implementation and improvement of selective reporting policies in microbiology laboratories at home and abroad.
Methods:
A cross-sectional study was conducted in a teaching tertiary hospital in China in July 2021. We designed selective reports and routine reports for urinary tract infections caused by
Escherichia coli
and lower respiratory tract infections caused by
Pseudomonas aeruginosa
. Questionnaires were conducted among participants by case vignettes, and 116 valid questionnaires were collected. The appropriateness rate of antibiotic prescription and the prescription rate of drug-resistant antibiotics, cephalosporins, fluoroquinolones, and carbapenems were calculated and compared between the selective reporting group and the routine reporting group in each case.
Results:
In most cases, we found that AST selective reporting could increase the appropriateness rate of antibiotic prescription (
p
< 0.05) and reduce the drug-resistant antibiotic prescription rate (
p
< 0.01), cephalosporin drug prescription rate (
p
< 0.05) and fluoroquinolone drug prescription rate (
p
< 0.01). Although the difference in carbapenems prescription rate was not significant, selective reporting could reduce the number of its prescriptions to some extent.
Conclusion:
AST selective reporting can help promote the appropriate use of antibiotics and reduce the use of broad-spectrum antibiotics. It is suggested to develop scientific and effective selective reporting practices and strengthen the two-way communication between clinicians and microbiology laboratories, thereby enabling microbiology laboratories to play a more important role in clinical antimicrobial management.
We report on a widely tunable, dual-wavelength, continuous-wave, mid-infrared optical parametric oscillator (OPO), pumped by a dual-wavelength fiber source that was realized by combining two fiber ...lasers in series. The OPO was designed as a four-mirror singly resonant cavity, in which a periodically poled lithium niobate (PPLN) crystal was used as nonlinear crystal. Two idler emissions with different wavelengths were observed, one being basically fixed at 3140 nm and the other being tunable from 3227 to 3413 nm. Under the maximum pump power, the total idler power was over 6 W and the corresponding pump-to-idler slope efficiency reached 11.4%. The generated signal beam had just one central wavelength around 1600 nm. Through theoretical analysis and experimental verification, it was analyzed that two nonlinear processes, OPO and intracavity difference frequency generation (DFG), simultaneously occurred in the resonant cavity. The experimental phenomena revealed large widened DFG gain spectrum, which was in absolute contrast to simulation results based on classical DFG theory. It indicated great potential in practical application such ultra-wide nonlinear frequency conversion.
Abstract
Planar magnetic structures (PMSs), characterized by interplanetary magnetic field vectors remaining parallel to a specific plane, are commonly observed in the solar wind, especially in the ...sheath region of interplanetary coronal mass ejections (ICMEs). In this study, PMS events in the 2 hr regions downstream of ICME-driven shocks were investigated to reveal the relationship between PMS formation and shock environment using data collected by the Parker Solar Probe, Solar Orbiter, and Venus Express spacecraft in the inner heliosphere. PMS events are identified in the majority (around 93%) of the postshock 2 hr regions, with transit times ranging from 10 to 120 minutes, which demonstrates their common occurrence associated with ICME-driven shocks. About 33% of the detected PMS events cover the whole 2 hr intervals, called full PMS events. Most of the full PMS events are observed in the downstream region of quasi-perpendicular shocks. In addition, statistical results show that full PMS events occurring in the downstream region of quasi-perpendicular shocks are generally associated with higher magnetic compression ratios, which implies that full PMS events are more likely to be formed in the downstream region of strong quasi-perpendicular shocks.
Neutrophils are significant compositions of solid tumors and exert distinct functions in different types of tumors. However, the precise role of neutrophils in the progression of breast cancer (BC) ...is presently unclear. In this study, by investigating the single-cell RNA sequencing data, we identify a new neutrophil subset, C5aR1-positive neutrophils, that correlates with tumor progression and poor survival for BC patients. Furthermore, it is discovered that C5aR1-positive neutrophils enhance BC cell glycolysis via upregulating ENO1 expression. Mechanically, C5aR1-positive neutrophil-secreted IL1β and TNFα cooperatively activate ERK1/2 signaling, which phosphorylates WTAP at serine341 and thereby stabilizes WTAP protein. The stabilization of WTAP further promotes RNA m6A methylation of ENO1, impacting the glycolytic activity of BC cells. Importantly, C5aR1-positive neutrophils also promote breast cancer growth in vivo, and this effect is abolished by WTAP silencing. In clinical BC samples, increased C5aR1-positive neutrophils correlate with elevated IL1β, TNFα, and ENO1 expression. A high co-expression of C5aR1-positive neutrophil gene signature and ENO1 predicts worse prognosis of BC patients compared with a low co-expression. Collectively, our study reveals a novel subset of C5aR1-positive neutrophils that induces breast cancer glycolysis via increasing ERK1/2-WTAP-dependent m6A methylation of ENO1. These findings support the potential for exploration of C5aR1-positive neutrophils as a therapeutic target in breast cancer.
Bamboo forests provide important ecosystem services and play an important role in terrestrial carbon cycling. Of the approximately 500 bamboo species in China, Moso bamboo (Phyllostachys pubescens) ...is the most important one in terms of distribution, timber value, and other economic values. In this study, we estimated current and potential carbon stocks in China's Moso bamboo forests and in their products. The results showed that Moso bamboo forests in China stored about 611.15 ± 142.31 Tg C, 75% of which was in the top 60 cm soil, 22% in the biomass of Moso bamboos, and 3% in the ground layer (i.e., bamboo litter, shrub, and herb layers). Moso bamboo products store 10.19 ± 2.54 Tg C per year. The potential carbon stocks reach 1331.4 ± 325.1 Tg C, while the potential C stored in products is 29.22 ± 7.31 Tg C a−1. Our results indicate that Moso bamboo forests and products play a critical role in C sequestration. The information gained in this study will facilitate policy decisions concerning carbon sequestration and management of Moso bamboo forests in China.
•Moso bamboo forest stored 611.15 ± 142.31 TgC, about 7.8% of that of China's forests.•C stocks in soil, vegetation and ground layers are 75%, 22% and 3%, respectively.•The potential carbon stocks of Moso bamboo forest can reach 1331.4 ± 325.1 TgC.•Current and potential Moso bamboo products store 10.19 ± 2.54 and 29.22 ± 7.31 TgC a−1.•Moso bamboo plantations play an essential role in carbon sink forestry in China.
The Martian‐induced magnetopause (IMP), characterized by the sudden changes of magnetic fields and ion compositions, is the transition boundary separating the magnetosheath from Martian induced ...magnetosphere. Based on the magnetic field and plasma measurements by Mars Atmosphere and Volatile EvolutioN, we for the first time report a magnetic reconnection at the dayside IMP. The clear plasma jet and bipolar Hall magnetic field provide solid evidence for the identification of the magnetic reconnection. Our observations demonstrate that the newly arrived interplanetary magnetic field and the anchored magnetic field in the induced magnetosphere can reconnect with each other at the IMP. Such reconnection allows the planetary ions to escape from Mars through the reconnected magnetic fields across the IMP, resulting in a significant increase in the local loss rate of the ionospheric ions.
Plain Language Summary
Magnetic reconnection is one of the most important topics in space physics since it can not only alter the topology of the magnetic field but also quickly convert magnetic energy to kinetic energy. Around Mars, magnetic reconnections are identified in various regions, such as the induced magnetosphere, ionosphere, magnetotail. However, the magnetic reconnection on the Martian induced magnetopause, which separates the induced magnetosphere from the shocked solar wind, has not been reported and analyzed yet. In this letter, we for the first time report a magnetic reconnection at the Martian magnetopause with Hall magnetic field and ion jet flow. The magnetic reconnections on the magnetopause are crucial because they can accelerate planetary heavy ions in the induced magnetosphere or ionosphere to facilitate their escape from Mars.
Key Points
Magnetic reconnection at the Martian induced magnetopause is reported
Hall magnetic field associated with the reconnection are detected by Mars Atmosphere and Volatile EvolutioN
The thickness of the reconnection region and local oxygen loss rate are estimated to be 575 km and ∼1.0⋅1024s−1, respectively
RNA functions are intrinsically tied to folding kinetics. The most elementary step in RNA folding is the closing and opening of a base pair. Understanding this elementary rate process is the basis ...for RNA folding kinetics studies. Previous studies mostly focused on the unfolding of base pairs. Here, based on a hybrid approach, we investigate the folding process at level of single base pairing/stacking. The study, which integrates molecular dynamics simulation, kinetic Monte Carlo simulation, and master equation methods, uncovers two alternative dominant pathways: Starting from the unfolded state, the nucleotide backbone first folds to the native conformation, followed by subsequent adjustment of the base conformation. During the base conformational rearrangement, the backbone either retains the native conformation or switches to nonnative conformations in order to lower the kinetic barrier for base rearrangement. The method enables quantification of kinetic partitioning among the different pathways. Moreover, the simulation reveals several intriguing ion binding/dissociation signatures for the conformational changes. Our approach may be useful for developing a base pair opening/closing rate model.
•Iron deposition significantly increases with aging in many subcortical nuclei, with uneven distribution within nuclei.•In PD, iron is progressively deposited in the substantia nigra and red ...nucleus.•In AD, iron is strongly deposited in caudate and putamen.•Regional iron deposition can delineate brain degeneration and predict the severity of neurodegenerative diseases.
Brain iron deposition is a promising marker for human brain health, providing insightful information for understanding aging as well as neurodegenerations, e.g., Parkinson's disease (PD) and Alzheimer's disease (AD). To comprehensively evaluate brain iron deposition along with aging, PD-related neurodegeneration, from prodromal PD (pPD) to clinical PD (cPD), and AD-related neurodegeneration, from mild cognitive impairment (MCI) to AD, a total of 726 participants from July 2013 to December 2020, including 100 young adults, 189 old adults, 184 pPD, 171 cPD, 31 MCI and 51 AD patients, were included. Quantitative susceptibility mapping data were acquired and used to quantify regional magnetic susceptibility, and the resulting spatial standard deviations were recorded. A general linear model was applied to perform the inter-group comparison. As a result, relative to young adults, old adults showed significantly higher iron deposition with higher spatial variation in all of the subcortical nuclei (p < 0.01). pPD showed a high spatial variation of iron distribution in the subcortical nuclei except for substantia nigra (SN); and iron deposition in SN and red nucleus (RN) were progressively increased from pPD to cPD (p < 0.01). AD showed significantly higher iron deposition in caudate and putamen with higher spatial variation compared with old adults, pPD and cPD (p < 0.01), and significant iron deposition in SN compared with old adults (p < 0.01). Also, linear regression models had significances in predicting motor score in pPD and cPD (Rmean = 0.443, Ppermutation = 0.001) and cognition score in MCI and AD (Rmean = 0.243, Ppermutation = 0.037). In conclusion, progressive iron deposition in the SN and RN may characterize PD-related neurodegeneration, namely aging to cPD through pPD. On the other hand, extreme iron deposition in the caudate and putamen may characterize AD-related neurodegeneration.
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