Underlying mechanisms governing on distribution and stratification of DOM during seasonal freeze-thaw cycles.

During the freeze-thaw cycles of ice-covered lakes, DOM undergoes a series of transformations including enrichment, dispersion, and filtration. However, the mechanisms and influence factors on lake pollution processes remain unclear. Therefore, this study investigates the distribution of DOM components and elucidate the role of ice-layer sieving its mechanisms within ice-water-sediments. Study identifies significant variations in the characteristics of DOM, protein-like substances tend to migrate towards the ice layer, while humic-like substances predominantly remain in water. This selective distribution is primarily influenced by the physical and chemical properties of DOM during the freezing process. The ice layer acts as a sieve, allowing smaller molecules such as protein-like substances to pass through more easily, while larger molecules like humic-like substances are retained in the water. Additionally, Temperature plays a pivotal role in affecting the contents of DOM. As the temperature decreases, the solubility of DOM decreases, leading to its precipitation and enrichment in sediments. Conversely, an increase in temperature can facilitate the release of DOM from sediments into the water. Furthermore, high content of total dissolved solids can affect the solubility and stability of DOM, potentially leading to changes in its composition and distribution. These insights provide a deeper understanding of the complex interplay between thermal processes and chemical dynamics within ice-covered aquatic environments. They offered valuable insights into the behavior of organic pollutants in frozen lake systems. The findings have potential implications for environmental management strategies aimed at mitigating the effects of climate.

Ropinirole suppresses LPS-induced periodontal inflammation by inhibiting the NAT10 in an ac4C-dependent manner.

BACKGROUND: Periodontitis is a chronic osteolytic inflammatory disease, where anti-inflammatory intervention is critical for restricting periodontal damage and regenerating alveolar bone. Ropinirole, a dopamine D2 receptor agonist, has previously shown therapeutic potential for periodontitis but the underlying mechanism is still unclear. METHODS: Human gingival fibroblasts (HGFs) treated with LPS were considered to mimic periodontitis in vitro. The dosage of Ropinirole was selected through the cell viability of HGFs evaluation. The protective effects of Ropinirole on HGFs were evaluated by detecting cell viability, cell apoptosis, and pro-inflammatory factor levels. The molecular docking between NAT10 and Ropinirole was performed. The interaction relationship between NAT10 and KLF6 was verified by ac4C Acetylated RNA Immunoprecipitation followed by qPCR (acRIP-qPCR) and dual-luciferase reporter assay. RESULTS: Ropinirole alleviates LPS-induced damage of HGFs by promoting cell viability, inhibiting cell apoptosis and the levels of IL-1ß, IL-18, and TNF-α. Overexpression of NAT10 weakens the effects of Ropinirole on protecting HGFs. Meanwhile, NAT10-mediated ac4C RNA acetylation promotes KLF6 mRNA stability. Upregulation of KLF6 reversed the effects of NAT10 inhibition on HGFs. CONCLUSIONS: Taken together, Ropinirole protected HGFs through inhibiting the NAT10 ac4C RNA acetylation to decrease the KLF6 mRNA stability from LPS injury. The discovery of this pharmacological and molecular mechanism of Ropinirole further strengthens its therapeutic potential for periodontitis.

Antibacterial activity of corydalis saxicola bunting total alkaloids against Porphyromonas gingivalis in vitro.

Aim: To investigate the antibacterial effects of Corydalis Saxicola bunting total alkaloid (CSBTA) on Porphyromonas gingivalis. Methods: SEM, chemical staining, RT-qPCR and ELISA were used to detect effects of CSBTA on P. gingivalis. Results: CSBTA treatment caused shrinkage and rupture of P. gingivalis morphology, decreased biofilm density and live bacteria in biofilm, as well as reduced mRNA expression of virulence genes hagA, hagB, kgp, rgpA and rgpB of P. gingivalis. Furthermore, NOK cells induced by CSBTA-treated P. gingivalis exhibited lower IL-6 and TNF-α expression levels. Conclusion: CSBTA is able to kill free P. gingivalis, disrupt the biofilm and weaken the pathogenicity of P. gingivalis. It has the potential to be developed as a drug against P. gingivalis infection.

Assessment of occurrence, partitioning and ecological risk for 144 steroid hormones in Taihu Lake using UPLC-MS/MS with machine learning model.

Steroid hormones (SHs) have attracted mounting attention due to their endocrine-disrupting effects on humans and aquatic organisms. However, the lack of analytical methods and toxicity data for a large number of SHs has limited the effective management of SH contamination in the water-sediment systems. In this study, we developed a highly sensitive analytical method for the simultaneous quantification of 144 SHs to investigate their occurrence, spatial distribution and partitioning in the water and sediment in Taihu Lake. The results showed that the total concentrations of SHs in water and sediment were 366.88-998.23 ng/L (mean: 612.84 ng/L) and 17.46-150.20 ng/g (mean: 63.41 ng/g), respectively. The spatial distribution of SHs in Taihu Lake might be simultaneously influenced by the pollution sources, lake hydrodynamics, and sediment properties. The sediment-water partitioning result implied that 28 SHs were in dynamic equilibrium at the water-water interface. In addition, 22 and 12 SHs tended to spread to water and settle into sediment, respectively. To assess the ecological risk of all SHs, a robust random forest model (R2 = 0.801) was developed to predict the acute toxicity of SHs for which toxicity data were not available from publications. Risk assessment showed that SHs posed a high ecological risk throughout Taihu Lake, with the highest risk in the northwestern areas. Estrone, 17ß-estradiol and 17α-ethynylestradiol were the dominant risk contributors and were therefore recommended as the priority SHs in Taihu Lake. This work provided a valuable dataset for Taihu Lake, which would help to provide guidance and suggestions for future studies and be useful for the government to develop the mitigation and management measures.

Characteristics of the presence and migration patterns of DOM between ice and water in the cold and arid Daihai Lake.

Seasonal ice cover plays a crucial role in shaping the physical characteristics of lakes in cold and arid regions. Moreover, the ice significantly affects the level and quality of dissolved organic matter (DOM) in the water column. We utilized spectroscopy and mass spectrometry to analyze the molecular composition and distribution of DOM in ice cores and under-ice water in Daihai Lake. We identified the main environmental factors affecting DOM migration through structural equation modelling (SEM). The freezing process created a repulsive effect on DOM, with water samples demonstrating a greater DOM content than ice. The dominant part of the DOM in the ice cores was mainly comprised of protein-like materials (71.45 %), whereas water consisted of humus-like materials (54.81 %). The average molecular weight of the ice cover DOM (m/z = 396.77) was smaller than in the under-ice water (m/z = 405.42). While low-molecular and low-aromatic protein-like material tended to be trapped in the ice layer during ice formation, large-molecular and highly aromatic humic substances were more easily expelled into the water. Interestingly, condensed aromatic hydrocarbons were found to occur less frequently in the ice phase (11 %) compared to the aqueous phase (13 %). Both the lipid and protein/aliphatic compound structures exhibited slightly higher ratios in the ice (6 % and 8 %, respectively) than in water (1 % and 5 %, respectively). SEM between the ice cover environment and DOM indicated that the ice can influence the distribution pattern of DOM through the regulation of internal solute factors and other chemicals. The nature of the DOM and the rate of ice growth also play critical roles in determining the distribution mechanism of DOM for ice and water. The pollutant distribution characteristics and migration patterns between ice and water are essential for comprehending environmental water pollution and promoting pollution management and protection measures in cold region lakes.

Corydalis saxicolaBunting total alkaloid eliminates Porphyromonas gingivalis strain 33277 internalized into macrophages by inhibition of TLR2.

OBJECTIVE: This study aimed to investigate the impact of Corydalis Saxicola Bunting Total Alkaloid (CSBTA) on Porphyromonas gingivalis internalization within macrophages and explore the potential role of Toll-Like Receptor 2 (TLR2) in this process. METHODS: We established a P. gingivalis internalization model in macrophages by treating P. gingivalis-infected macrophages (MOI=100:1) with 200 µg/mL metronidazole and 300 µg/mL gentamicin for 1 h. Subsequently, the model was exposed to CSBTA at concentrations of 0.02 g/L or 1 µg/mL Pam3CSK4. After a 6 h treatment, cell lysis was performed with sterile water to quantify bacterial colonies. The mRNA expressions of TLR2 and interleukin-8 (IL-8) in macrophages were analyzed using RT-qPCR, while their protein levels were assessed via Western blot and ELISA respectively. RESULTS: P. gingivalis could internalize into macrophages and enhance the expression of TLR2 and IL-8. Activation of TLR2 by Pam3CSK4 contributed to P. gingivalis survival within macrophages and increased TLR2 and IL-8 expression. Conversely, 0.02 g/L CSBTA effectively cleared intracellular P. gingivalis, achieving a 90 % clearance rate after 6 h. Moreover, it downregulated the expression of TLR2 and IL-8 induced by P. gingivalis. However, the inhibitory effect of CSBTA on the internalized P. gingivalis model was attenuated by Pam3CSK4. CONCLUSION: CSBTA exhibited the ability to reduce the presence of live intracellular P. gingivalis and lower IL-8 expression in macrophages, possibly by modulating TLR2 activity.

Iron-modified carriers accelerate biofilm formation and resist anammox bacteria loss in biofilm reactors for partial denitrification-anammox.

The slow formation of anammox biofilms presents a bottleneck for resolving anammox bacterial loss and achieving stable performance in biofilm-based partial denitrification-anammox (PD-A) processes. This study utilized iron-modified (K1/Fe3O4 NPs) carriers, which were prepared and used for the first time in PD-A processes. Parallel moving bed biofilm reactors (MBBRs) indicated that iron-modified carriers facilitated the formation of biofilms at a faster rate than K1 carriers, consequently improving the nitrogen removal performance of the process by over 40 %. 16S rDNA analysis showed that anammox bacteria were approximately four times more abundant in the iron-modified carrier biofilm than in the K1 carrier biofilm. XPS and zeta potential analysis suggested that the improved microbial affinity of the iron-modified carrier surface caused this. As a result, the iron-modified carriers facilitated the formation of anammox biofilms and enhanced PD-A performance.

The pollution of microplastics in sediments of the Yangtze River Basin: Occurrence, distribution characteristics, and basin-scale multilevel ecological risk assessment.

Microplastics (MPs) pollution in the Yangtze River Basin (YRB) of China has grown to be a serious issue, yet there is a lack of understanding of the environmental risks of MPs in the sediment of the entire basin. This work revealed the spatial distribution characteristics of MPs in YRB sediments, and it methodically assessed the ecological risks of MPs by taking into consideration their abundance, toxic effects, and polymer types. The results showed a high heterogeneity in the abundance of MPs in YRB sediments, with an average of 611 particles/kg dry weight (DW) sediment. Small-sized MPs (<1 mm), fibrous, transparent-colored and polypropylene (PP) accounted for the majority with 71.6%, 68%, 37% and 30.8%, respectively. Correlation analysis indicated significant influences of human activities such as population, industrial structure, and urban wastewater discharge on the abundance and morphological types of MPs in sediments. Based on chronic toxicity data exposed to sediments, a predicted no-effect concentration (PNEC) of 539 particles/kg DW was calculated using the species susceptibility distribution (SSD). Multiple deterministic risk assessment indices indicated that MPs in YRB sediments exhibited primarily low pollution load levels, moderate-to-low potential ecological risk levels, and high levels of polymer pollution. However, probabilistic risk assessment revealed an overall low risk of MPs in YRB sediments. Monte Carlo simulation results demonstrated that polyvinyl chloride (PVC) and polycarbonate (PC) made a great contribution to ecological risk and should be considered as priority control pollutants in MPs. In addition, various assessments showed that the ecological risk of MPs in river sediments was higher than that in lake reservoir sediments. This is the first study to comprehensively assess the ecological risk of MPs in sediments of the YRB, which improves the understanding of the basin-wide occurrence characteristics and environmental risks of MPs in freshwater systems.

Distribution, abundance, and risks posed by microplastics in surface waters of the Yangtze River Basin, China.

Microplastic (MP) pollution in the Yangtze River Basin, China, has become an environmental issue of great concern. However, most studies on MPs have focused on a part of the Yangtze River Basin, and still lack knowledge on the risk of MPs exposure in surface waters of the whole basin. This study overviews the differences in abundance and spatial distribution of MPs in surface waters basin-wide and comprehensively assesses the ecological risk of MPs exposure in surface waters of the Yangtze River Basin by considering the abundance and toxicity effects. The results showed that the MP abundance at the collected sampling sites ranged from 0 to 44,080 particles/m3, with a mean of 3441 particles/m3. MPs were unevenly distributed throughout the basin, with hotspots such as Three Gorges Reservoir, Yangtze River estuary, and some urban lakes showing relatively higher abundance than the surroundings. Based on the available toxicity data, chronic and acute predicted no-effect concentrations (PNECs) of 12.3 particles/L and 21 particles/L were derived for freshwater MPs exposure using constructed species sensitivity distributions (SSDs). The hazard quotient (HQ) method was used to compare the environmental exposure concentrations of MPs with PNECs, and the results showed that 71.8% of the sampling sites in the Yangtze River Basin had moderate chronic ecological risk, while 43% of the sampling sites had moderate acute ecological risk. Overall, the ecological risk of MPs in lake and reservoir water was higher than that in river water. Joint probability curves (JPCs) showed that the overall risk probability of MPs in the surface water of the Yangtze River Basin was lower than that of other basins in China and other countries. This research provides valuable information for the ecological risk assessment of MPs at the watershed scale.

An overview of plutonium isotopes in soils, China: Distribution, spatial patterns, and sources.

Plutonium (Pu) is an anthropogenic radionuclide which has drawn significant attentions due to its radiotoxicity, and the sources of plutonium linked with nuclear accidents and contaminations. The 240Pu/239Pu atom ratio is source dependent and can be used as a fingerprint to determine the sources of radioactive contaminant. However, the distribution and sources of plutonium in soils of China have not yet been systematically studied at a national scale up to date. The distribution, spatial patterns, and sources of plutonium in soils of China were discussed in this work. The concentrations of 239,240Pu are in the range of 0.002-4.824 mBq/g with a large variation, and the 239,240Pu concentrations in surface soils increase with the increasing latitude, which affects by multi-factors such as organic matter and particle size, etc. The inventories of 239,240Pu are in the range of 7.31-554 Bq/m2. The weighted average of 240Pu/239Pu atom ratios (0.180 ± 0.004) in all surface samples is good agreement with the ratio of global fallout (0.180 ± 0.014) of the nuclear weapons tests, this indicate that the major source of plutonium in China is global fallout. However, among some sites, distinctly lower 240Pu/239Pu atom ratio compared to the global fallout values were observed in the northwest China, indicating a significant contribution from other source besides the global fallout. Furthermore, the spatial clustering patterns of hot spots (high values) and cold spots (low values) for plutonium showing the clear associations with nuclear tests, especially the Chinese Lop Nor nuclear weapons tests (CNTs) and the Semipalatinsk nuclear weapons tests (STS). Radioactive material including plutonium from the STS or CNTs was transported by the prevailing westerlies to the northwest China. This review about the fingerprints and distribution of plutonium in soils of China will help researchers to establish a reference database for future radiation risk assessment and environmental radioactive management.

Expression profile analysis of long noncoding RNA and messenger RNA during mouse cementoblast mineralization.

BACKGROUND AND OBJECTIVE: Emerging evidence has uncovered that long noncoding RNAs (lncRNAs) and messenger RNAs (mRNAs) exert biofunctions on cellular mineralization and bone formation. In this study, we aimed to identify lncRNA-mRNA expression profiles and expression patterns, and explore their underlying biofunctions during cementoblast mineralization. MATERIALS AND METHODS: Cementoblasts were cultured in mineralized medium for 0, 7, and 14 days. We used quantitative real-time polymerase chain reaction (qRT-PCR) and western blot (WB) to detect expression levels of osteocalcin (OCN), bone sialoprotein (BSP), and Osterix (Osx). Alkaline phosphatase (ALP) staining and alizarin red staining (ARS) were conducted to detect ALP activity and number of mineralized nodule. Total RNA was extracted from cells and used for high-throughput sequencing. EBSeq package was applied to analyze differentially expressed genes. Mfuzz R package was used to identify gene expression patterns. The weighted gene co-expression network analysis (WGCNA) was performed to explore co-expressed mRNAs of differentially expressed lncRNAs (DElncRNAs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were adopted by Clusterprofile R package. RESULTS: Cementoblasts were successfully induced by osteogenic medium. Compared with those on day 0, 384 DElncRNAs and 4255 differentially expressed mRNAs (DEmRNAs), respectively, were found on day 7. Meanwhile, 645 DElncRNAs and 4717 DEmRNAs were detected on day 14. Both DElncRNAs and DEmRNAs were classified into six clusters with different expression patterns. DEmRNAs and co-expressed mRNA of DElncRNAs were predominantly related to cell process, binding, phosphatidylinositol-3 kinase (PI3K)-Akt signaling pathway, hypoxia-inducible factor-1 (HIF-1) signaling pathway, mitogen-activated protein kinase (MAPK) signaling pathway, and hippo signaling pathway. CONCLUSION: The results demonstrated that both noncoding and coding RNAs were involved in the process of mineralization in cementoblasts, which may provide a new database for further study.

Pollution levels and risk assessment of thallium in Chinese surface water and sediments.

Thallium (Tl) is one of the most toxic metals and can cause chronic and acute damage to humans. Due to occurrences of incidents involving Tl pollution in China, its potential environmental impacts are receiving increased attention. However, there is still limited information on Tl concentrations in the environment and their risks to human health and wildlife. This paper provides an overview of the contamination of surface water and sediments by Tl across China and assesses the potential risks using several methods. The acute and chronic aquatic life criteria for Tl were determined to be 13.25 and 1.65 µg/L, respectively. The acute and chronic risk quotients (RQs) of Tl in surface water near mining areas were 0.01-41.51 and 0.20-666.67, respectively, indicating medium to high ecological risks to aquatic organisms. Tl in sediments of Pearl and Gaofeng rivers pose a high risk based on the higher geo-accumulation index (Igeo) and potential ecological risk index (EI) values. Exposure parameters for the Chinese population were used to derive health criteria and assess non-carcinogenic risk posed by Tl in centralized drinking water sources. Tl criteria for protection of human health were calculated to be 0.18 µg/L for water+organisms and 0.30 µg/L for organisms only. The non-carcinogenic risk posed by Tl was acceptable. The human health criteria of Tl for children were the lowest among all age groups. The risks posed by Tl to health of children are greater than those for adults. Therefore, emphasis should be placed on protecting children from exposure to Tl. For the Chinese population, the drinking water guidance value to ensure protection of human health was determined to be 0.44 µg/L. The availability of multiple Tl guidance values for designated water uses will improve the environmental regulation and surveillance of Tl pollution in China and other countries.

Assessing Heavy Metal Pollution of the Largest Nature Reserve in Tianjin City, China.

Beidagang Wetland (BW) Nature Reserve is centrally situated in Tianjin City, experiencing an extreme industrial development. This study uses index characteristic analysis systems for assessing the individual and combined heavy metal pollution loading in the water during the spring and autumn seasons. By combining the pollution level of single pollutant, a more comprehensive evaluation of water quality in BW was achieved. Water quality was worst during autumn due to high level of Cd and Pb, which indicate the type of anthropogenic activities have a serious effect on heavy metal pollution in BW. In addition, high exchangeable amounts of Cd (> 40%) were found in the sediments of BW, indicating Cd pollution has emerged. There is a need for appropriate abatement actions curbing heavy metal loading and improving water quality of the BW Nature Reserve, thereby ensuring a sustainable management of its ecosystem services.

Metagenomic analysis of microbial community structure and distribution of resistance genes in Daihai Lake, China.

The emergence of resistance genes is a global phenomenon that poses a significant threat to both animals and humans. Lakes are important reservoirs of genes that confer resistant to antibiotics and metals. In this study, we investigated the distribution and diversity of antibiotic resistance genes (ARGs) and metal resistance genes (MRGs) in the sediment of Daihai Lake using high-throughput sequencing and metagenomic analysis. The results indicated that all sampling sites had similar bacterial community structures, with Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes being the most abundant. A total of 16 ARG types containing 111 ARG subtypes were deposited in the sediment. Among the resistance genes to bacitracin, multidrug, macrolide-lincosamide-streptogramin (MLS), tetracycline, beta-lactam, and sulfonamide were the dominant ARG types, accounting for 89.9-94.3% of the total ARGs. Additionally, 15 MRG types consisting of 146 MRG subtypes were identified. In all samples, MRGs of the same type presented resistance to Pb, Ni, Hg, W, Zn, Ag, Cr, Fe, As, Cu, and multimetals. Overall, the distribution and diversity of antibiotic and metal resistance genes showed no significant differences in the samples. Plasmids (91.03-91.82%) were the most dominant mobile genetic elements in the sediments of Daihai Lake. Network analysis indicated that the target ARGs and MRGs were significantly positively correlated with the microorganisms. Potential hosts for various ARGs and MRGs include Proteobacteria, Euryarchaeota, Actinobacteria, Chloroflexi, and Bacteroidetes.

Distribution of plutonium isotopes in soils between two nuclear test sites: Semipalatinsk and Lop Nor.

Plutonium (Pu) has attracted attention as an environmental tracer due to its radiotoxicity and the possibility of sources linked with nuclear accidents in recent years. Plutonium isotopes (239,240Pu) were detected at trace levels in soils collected from the Xinjiang region located between the Semipalatinsk nuclear test site and China's Lop Nor nuclear test site. Little is known regarding the spatial variation of 239,240Pu in soils from this region. This study reports the use of Sector Field Inductively Coupled Plasma Mass Spectrometry (SF-ICP-MS) methods to distinguish between Pu isotopes derived from global fallout and nuclear weapon tests. We found that the 239,240Pu activity concentrations ranged from 0.035 to 1.338 mBq/g; the 240Pu/239Pu atomic ratios were 0.157-0.223 with a weighted average of 0.180 ± 0.002, corresponding with the expected average global fallout ratio of 0.180 ± 0.014. This indicated that global fallout is the major source of Pu in the study region. The 239,240Pu inventories in these soils ranged from 23.67 to 222.7 Bq/m2, corresponding with those from other areas in China and other countries within the latitude range. Our Pu isotope data was supplemented with other published Pu data for soils collected in the vicinity of the Semipalatinsk nuclear test site and Lop Nor nuclear test site. Results indicate that 239,240Pu inventories and 240Pu/239Pu atomic ratios in soils exhibit large variations with distance from the Semipalatinsk nuclear test site. High deposition and accumulation of Pu, and low 240Pu/239Pu ratios were observed in close-in fallout and downwind regions of the Semipalatinsk nuclear test site and China's Lop Nor nuclear test site.

Review on Health Impacts from Domestic Coal Burning: Emphasis on Endemic Fluorosis in Guizhou Province, Southwest China.

Endemic fluorosis in Guizhou Province, Southwest China was firstly reported by Lyth in 1946 and was extensively concerned since the early 1980s. Initially, the pathological cause of endemic fluorosis in Guizhou Province was instinctively ascribed to the drinking water. However, increasing evidences pointed that the major exposure route of fluorine for the local residents is via the roasted foodstuffs, especially the roasted pepper and corn. Source of fluorine in roasted foodstuffs was once blamed on the local coal and subsequently imputed to clay mixed in the coal. In fact, both are probably the source. Geogenic fluorine concentration in soil and clay is indeed high in Guizhou Province, but is not likely to be the direct cause for endemic fluorosis. The real culprit for endemic fluorosis in Guizhou Province is the unhealthy lifestyle of the local residents, who usually roasted their foodstuffs using local coal or briquettes (a mixture of coal and clay), resulting in the elevated fluorine in roasted foodstuffs. Nowadays, endemic fluorosis in Guizhou Province has substantially mitigated. Nevertheless, millions of confirmed cases of dental fluorosis remain left. In addition to endemic fluorosis, other health problems associated with domestic coal burning may also exist, because of the enrichment of toxic/harmful elements in the local coal. It is necessary to determine how serious the situation is and find out the possible solution. As people in other developing countries may suffer from similar health issues, same health issues around the world deserve more attention.

Dynamic simulation of nutrient distribution in lakes during ice cover growth and ablation.

Nutrient transport in seasonally ice-covered lakes is an important factor affecting spring algal blooms in eutrophic waters; because phase changes during the ice growth process redistribute the nutrients. In this study, nutrient transport under static conditions was simulated by using two ice thickness models in combination with an indoor freezing experiment under different segregation coefficient conditions for nutrients. A real-time prediction model for nutrient and pollutant concentrations in ice-covered lakes was established to explore the impact of the ice-on period in eutrophic shallow lakes. The results demonstrated that the empirical degree-day model and the high-resolution thermodynamic snow and sea-ice model (HIGHTSI) could both be used to simulate lake ice thickness. The empirical degree-day model performed better at predicting the maximum ice thickness (measured thickness 0.22-0.55 m; simulated thickness 0.48 m), whereas the HIGHTSI model was more accurate when estimating the mean thickness (5-6% error). When simulating ice growth, the HIGHTSI model considered more meteorological factors impacting ice cover ablation; hence, it performed better during the ablation stage relative to the empirical degree-day model. Two non-dynamic nutrient transport models were developed by combining the segregation coefficient model and the ice thickness prediction model. The HIGHTSI nutrient transport model can be used to predict real-time changes in nutrient concentrations under ice cover, and the degree-day model can be used to predict changes in the lake water ecosystem.

Effect mechanism of biochar application on soil structure and organic matter in semi-arid areas.

There are global concerns regarding soil remediation and water conservation in arid and semi-arid areas. Studying the mechanism and factors influencing soil structure and organic matter content is very important for soil remediation and the rational utilization of water resources. We tracked the changes in soil aggregates and organic matter content during the growth period of maize using different application rates of straw biochar (10, 20, 30, and 50 t/ha) to investigate the effects of biochar on the structure of weakly alkaline soil. The results were as follows: 1) Biochar significantly increased the content of water-stable soil aggregates. The content of water-stable macroaggregates (≥0.25 mm) increased by 8.3-35.0%, and the increase was the highest (35%) when biochar was applied at a rate of 30 t/ha 2) After applying biochar, the content of air-dried aggregates on the surface layer increased by 112.6-168.5%. 3). Biochar increased the organic matter content to varying degrees from the spatiotemporal aspect. In terms of soil depth, organic matter content increased by 2.15-5.88 g/kg. The jointing stage, which the time demand for organic matter is the highest, organic matter content increased by 35.4% when biochar was applied at 50 t/ha 4) We established a three-dimensional surface correlation equation based on the synergistic relationships among biochar, water-stable aggregates, and organic matter content. The particle size of soil aggregates was the highest when the biochar application rate was 29.38 t/ha and the organic matter content increased by 25.7%. It provided evidence that applies to biochar has good potential for water-saving irrigation and soil remediation.

The effect of the surgical microscope on the outcome of root scaling.

The benefits of using a surgical microscope in periodontal therapy were mainly based on subjective statements made by patients or periodontists. We aimed to provide laboratory evidence for the advantages of using a surgical microscope during root scaling on periodontitis teeth. In the present study, the extracted teeth were categorized into four groups: normal teeth (normal control [NC] group), untreated periodontitis teeth (periodontitis control [PC] group), root surface scaled without magnification (macro group), and root surface instrumented with a microscope (micro group). To analyze both the mechanical and biological properties of the root surfaces, we performed nanoindentation in addition to the traditional methods. We found that by using a surgical microscope, we improved the clearance of bacterial deposits and calculi on periodontitis root surfaces. Nanoindentation results revealed that the nanotopography pattern, elastic modulus, and nanohardness of the root surface in the micro group were closest to those in the NC group. The immunofluorescence assay and cell proliferation analyses revealed improved morphology and enhanced adhesion and proliferation of periodontal ligament cells on the root surface in the micro group compared with the macro group. After instrumentation, the expression levels of interleukin-6 and interleukin-8 decreased when compared with the PC group. Our results demonstrated that surgical microscope application could improve the outcomes of periodontal treatment, implying that a surgical microscope can be a powerful tool for periodontists to seek accurate clinical periodontal performance and gain better biocompatibility of the treated root surfaces.

Integrin-α9 and Its Corresponding Ligands Play Regulatory Roles in Chronic Periodontitis.

Integrin-α9 (ITGA9) and its corresponding ligands are involved in inflammatory and immune responses. The present study aimed to investigate whether ITGA9 participates in the development of chronic periodontitis (ChP) and to explore the underlying mechanisms. We collected gingival tissue and gingival crevicular fluid in vivo from patients to determine the levels of ITGA9 and its ligands. We cultured primary periodontal ligament cells (PDLCs) in vitro and applied small interfering RNA to knock down ITGA9 in order to analyze the changes of inflammatory cytokines and explore the related cellular signaling pathways. The expression level of ITGA9 was significantly higher in the gingiva of patients with ChP than that of healthy individuals. ITGA9 knockdown in the PDLCs inhibited the secretion of interleukin (IL)-1ß, IL-6, and IL-8. Western blot analysis indicated that this change could be attributed to the regulation of the mitogen-activated protein kinase (MAPK) signaling pathway. ITGA9 plays a regulatory role in the homeostasis of ChP. The results of the present study provide potential insights into the treatment of periodontitis. Graphical abstract.