Declined nutrients stability shaped by water residence times in lakes and reservoirs under climate change.

Water quality stability in lakes and reservoirs is essential for drinking water safety and ecosystem health, especially given the frequent occurrence of extreme climate events. However, the relationship between water quality stability and water residence time (WRT) has not been well elucidated. In this study, we explored the relationship based on nitrogen (N) and phosphorus (P) concentrations data in 11 lakes and 49 reservoirs in the Yangtze-Huaihe River basin from 2010 to 2022. Additionally, we examined the effects of hydrometeorological characteristics, the geomorphology of water bodies and catchments, and land use on the WRT, establishing a link between climate change and the stability of N and P in these water bodies. The results showed that a significant correlation between the stability of N and P in lakes and reservoirs and their WRT. The longer WRT tends to coincide with decreased stability and higher nutrient concentrations. Hydrometeorological factors are the primary factors on the WRT, with precipitation exerting the greatest effect, particularly under extreme drought. In recent years, extreme climatic events have intensified the fluctuations of WRT, resulting in a renewed increase in N and P concentrations and deterioration in stability. These findings highlight the importance of incorporating meteorological and hydrological factors alongside reinforcing ecological restoration into lake and reservoir management strategies, and providing a scientific basis for future efforts aimed at enhancing lake and reservoir water quality stability and safeguarding aquatic ecosystems.

The high electron mobility for spin-down channel of two-dimensional spin-polarized half-metallic ferromagnetic EuSi2N4 monolayer.

The two-dimensional (2D) monolayer material MoSi2N4 was successfully synthesized in 2020[Hong et al., Science 369, 670, (2020)], exhibiting a plethora of new phenomena and unusual properties, with good stability at room temperature. However, MA2Z4 family monolayer materials involve primarily transition metal substitutions for M atoms. In order to address the research gap on lanthanide and actinide MA2Z4 materials, this work conducts electronic structure calculations on novel 2D MSi2N4 (M = La, Eu) monolayer materials by employing first-principles methods and CASTEP. High carrier mobility is discovered in the indirect bandgap semiconductor 2D LaSi2N4 monolayer (~5400 cm2 V-1 s-1) and in the spin (spin-down channel) carrier mobility of the half-metallic ferromagnetic EuSi2N4 monolayer (~2800 cm2 V-1 s-1). EuSi2N4 monolayer supplements research on spin carrier mobility in half-metallic ferromagnetic monolayer materials at room temperature and possesses a magnetic moment of 5 µB, which should not be underestimated. Furthermore, due to the unique electronic band structure of EuSi2N4 monolayer (with the spin-up channel exhibiting metallic properties and the spin-down channel exhibiting semiconductor properties), it demonstrates a 100% spin polarization rate, presenting significant potential applications in fields such as magnetic storage, magnetic sensing, and spintronics.

Probing the Structural and Electronic Properties of the Anionic and Neutral Tellurium-Doped Boron Clusters TeBnq (n = 3-16, q = 0, -1).

In this study, we employ density functional theory along with the artificial bee colony algorithm for cluster global optimization to explore the low-lying structures of TeBnq (n = 3-16, q = 0, -1). The primary focus is on reporting the structural properties of these clusters. The results reveal a consistent doping pattern of the tellurium atom onto the in-plane edges of planar or quasi-planar boron clusters in the most energetically stable isomers. Additionally, we simulate the photoelectron spectra of the cluster anions. Through relative stability analysis, we identify three clusters with magic numbers -TeB7-, TeB10, and TeB12. The aromaticity of these clusters is elucidated using adaptive natural density partitioning (AdNDP) and magnetic properties analysis. Notably, TeB7- exhibits a perfect σ-π doubly aromatic structure, while TeB12 demonstrates strong island aromaticity. These findings significantly contribute to our understanding of the structural and electronic properties of these clusters.

Aromatic and magnetic properties in a series of heavy rare earth-doped Ge6 cluster anions.

A series of pentagonal bipyramidal anionic germanium clusters doped with heavy rare earth elements, REGe 6 - (RE = Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), have been identified at the PBE0/def2-TZVP level using density functional theory (DFT). Our findings reveal that the centrally doped pentagonal ring structure demonstrates enhanced stability and heightened aromaticity due to its uniform bonding characteristics and a larger charge transfer region. Through natural population analysis and spin density diagrams, we observed a monotonic decrease in the magnetic moment from Gd to Yb. This is attributed to the decreasing number of unpaired electrons in the 4f orbitals of the heavy rare earth atoms. Interestingly, the system doped with Er atoms showed lower stability and anti-aromaticity, likely due to the involvement of the 4f orbitals in bonding. Conversely, the systems doped with Gd and Tb atoms stood out for their high magnetism and stability, making them potential building blocks for rare earth-doped semiconductor materials.

Maternal or Paternal Antibiotics? Intergenerational Transmission and Reproductive Toxicity in Zebrafish.

Despite the known direct toxicity of various antibiotics to aquatic organisms, the potential chronic impact through intergenerational transmission on reproduction remains elusive. Here, we exposed zebrafish to a mixture of 15 commonly consumed antibiotics at environmentally relevant concentrations (1 and 100 µg L-1) with a cross-mating design. A high accumulation of antibiotics was detected in the ovary (up to 904.58 ng g-1) and testis (up to 1704.49 ng g-1) of F0 fish. The transmission of antibiotics from the F0 generation to the subsequent generation (F1 offspring) was confirmed with a transmission rate (ki) ranging from 0.11 to 2.32. The maternal transfer of antibiotics was significantly higher, relative to paternal transfer, due to a greater role of transmission through ovarian enrichment and oviposition compared to testis enrichment. There were similar impairments in reproductive and developmental indexes on F1 eggs found following both female and male parental exposure. Almost all antibiotics were eliminated in F2 eggs in comparison to F1 eggs. However, there were still reproductive and developmental toxic responses observed in F2 fish, suggesting that antibiotic concentration levels were not the only criterion for evaluating the toxic effects for each generation. These findings unveil the intergenerational transmission mechanism of antibiotics in fish models and underscore their potential and lasting impact in aquatic environments.

If we should remove internal fixation devices for rib fractures?

BACKGROUND: Internal fixation for rib fractures has been widely carried out worldwide, and its surgical efficacy has been recognized. However, there is still controversy about whether implant materials need to be removed. At present, the research on this topic is still lacking at home and abroad. Therefore, in this study, the patients undergoing removal of internal fixation for rib fractures in our department within one year were followed up, to statistically analyze implant-related complications, postoperative complications and postoperative remission rate. METHODS: A retrospective analysis was conducted on 143 patients undergoing removal of internal fixation for rib fractures from 2020 to 2021 in our center. The implant-related complications, postoperative complications and postoperative remission rate of patients with internal fixation were analyzed. RESULTS: In this study, a total of 143 patients underwent removal of internal fixation, among which 73 suffered from preoperative implant-related complications (foreign-body sensation, pain, wound numbness, sense of tightness, screw slippage, chest tightness, implant rejection), and 70 had no post operative discomfort but asked for removal of internal fixation. The average interval between rib fixation and removal was 17 ± 9.00 (months), and the average number of removed materials was 5.29 ± 2.42. Postoperative complications included wound infection (n = 1) and pulmonary embolism (n = 1). of the 73 patients with preoperative implant-related complications, the mean postoperative remission rate was 82%. Among the 70 patients without preoperative discomfort, the proportion of discomforts after removal was 10%. No perioperative death occurred. CONCLUSION: For patients with internal fixation for rib fractures, removal of internal fixation can be considered in the case of implant-related complications after surgery. The corresponding symptoms can be relieved after removal. The removal presents low complication rate, and high safety and reliability. For patients without obvious symptoms, it is safe to retain the internal fixation in the body. For the asymptomatic patients who ask for removal of internal fixation, the possible risk of complications should be fully informed before removal.