[Air Pollutant Spatiotemporal Evolution Characteristics and Effects on Human Health in Xi'an City].

Xi'an is the political, economic, and cultural center of northwest China with a developed industry. Air pollution incidents have brought great challenges to the high-quality development of the social economy. It is vital to study air pollution characteristics and clarify their impact on human health. In this study, we first analyzed the spatiotemporal variations in air pollutants in the study region from 2015 to 2021. Then, the air quality index (AQI), aggregate air quality index (AAQI), and health risk-based air quality index (HAQI) were used to assess health risks. Based on these, the AirQ2.2.3 model was used to quantify health effects. The results showed that the major pollutants were PM10, PM2.5, and O3. The main pollution characteristics of the study area were terrain characteristics and the mixed pollution of anthropogenic emissions. Compared to that of AQI, AAQI and HAQI showed better classification performance for pollution levels. HAQI revealed that approximately 80 % of the population was exposed to unhealthy air throughout the year in the study region. People were most exposed to unhealthy air in winter, followed by autumn and spring, and the least in summer. The AirQ2.2.3 model quantified the total mortality proportions attributable to PM2.5, PM10, SO2, CO, NO2, and O3, which were 0.99 %, 2.04 %, 0.41 %, 1.72 %, 8.76 %, and 3.67 %, respectively. The attributable proportion of mortality of the respiratory system and cardiovascular diseases was consistent with the change rule of total mortality.

Short-term legacy effects of long-term nitrogen and water addition on soil chemical properties and micro-bial characteristics in a temperate grassland.

Nitrogen deposition and summer precipitation in eastern Inner Mongolia are predicted to increase in recent decades. However, such increases in nitrogen inputs and precipitation may not be continuous under the future new patterns of global change, with the direction and magnitude of which may change or weaken. The legacy effects of nitrogen and water addition after cessation on ecosystems are still unclear. Based on a 13-year nitrogen and water addition experiment in temperate grassland of northern China, we examined the short-term (2 years) legacy effects of historical nitrogen and water addition on soil physicochemical properties and microbial properties after the cessation of nitrogen and water addition in the 14th year. The results showed that the positive effects of historical nitrogen addition on most of soil nutrient variables diminished after two years of cessation, including ammonium nitrogen, nitrate nitrogen, dissolved organic carbon and nitrogen, and Olsen-P concentrations. In contrast, there were legacy effects on soil microbial characteristics. For example, the historical nitrogen input of 15 g N·m-2·a-1 reduced microbial biomass carbon, respiration, and alkaline phosphomonoesterase activity by 73.3%, 81.9%, and 70.3% respectively. It implied that microbial parameters restored slowly in comparison with soil nutrients, showing a hysteresis effect. Results of Pearson's correlation and redundancy analysis showed that the legacy effects of historical nitrogen addition on microbial parameters could be attributed to the negative effects of nitrogen addition on soil pH. Historical water addition showed significant legacy effects on soil pH, ammonium nitrogen, dissolved organic carbon and nitrogen, respiration, and soil enzyme activities, which significantly interacted with historical nitrogen addition. These results are of great significance to predict the changes in grassland ecosystem functions and services under the local environmental improvement conditions, and to reveal the restoration mechanism of degraded grassland.

A Review of Ultrafine-Grained Magnetic Materials Prepared by Using High-Pressure Torsion Method.

High-pressure torsion (HPT) is a severe plastic deformation technique where a sample is subjected to torsional shear straining under a high hydrostatic pressure. The HPT method is usually employed to create ultrafine-grained nano-structures, making it widely used in processing many kinds of materials such as metals, glasses, biological materials, and organic compounds. Most of the published HPT results have been focused on the microstructural development of non-magnetic materials and their influence on the mechanical properties. The HPT processing of magnetic materials and its influence on the structural and magnetic properties have attracted increasing research interest recently. This review describes the application of HPT to magnetic materials and our recent experimental results on Mn3O4, Mn4N, and MnAl-based alloys. After HPT, most magnetic materials exhibit significantly reduced grain size and substantially enhanced coercivity.

[Responses of soil physicochemical properties and microbial characteristics to mowing and nitrogen addition in a meadow steppe in Inner Mongolia, China.] / å† è’™å¤è‰ç”¸è‰åŽŸåœŸå£¤ç†åŒ–æ€§è´¨å’Œå¾®ç”Ÿç‰©å­¦ç‰¹æ€§å¯¹åˆˆå‰²ä¸Žæ°®æ·»åŠ çš„å“åº”.

Frequent mowing and nitrogen enrichment can lead to the degradation of grassland ecosystem. It remains largely unknown that how the soil microbial characteristics, important bio-indicators of soil quality, respond to mowing and nitrogen enrichment. In this study, using a field experiment established in the meadow steppe in Hulunber, Inner Mongolia, we explored the responses of soil properties, microbial biomass, soil respiration, and soil enzyme activities to mowing and nitrogen addition during growing seasons. Mowing significantly reduced microbial biomass carbon, nitrogen and phosphorus, and soil respiration (basal respiration and substrate induced respiration), which might be caused by the moisture- and carbon-limitation. Mowing significantly reduced activities of the enzymes involved in nitrogen acquisition (N-acetyl-ß-D-glucosaminidase) and phosphorus acquisition (acidic phosphomonoesterases), which supports the resource allocation theory. Soil pH was significantly reduced by N addition. However, microbial biomass showed no significant response to nitrogen input, implying that soil acidification induced by nitrogen inputs was not profound enough to affect microbial biomass. Nitrogen addition did not affect soil respiration and microbial enzymatic activities, inconsistent with results from most of previous studies conducted in typical steppe. Combination of mowing and nitrogen addition reduced the activity of acidic phosphomonoesterases, which might be due to the increased phosphorus availability under the combined treatment. Combination of mowing and nitrogen addition reduced microbial biomass phosphorus, but increased soil available phosphorus, corresponding to the lowered activity of acidic phosphomonoesterases under the combined treatment. Microbial biomass carbon, nitrogen and phosphorus, and soil respiration peaked in July, which was associated with the high temperature and precipitation in summer. Soil enzymatic activities were higher in the spring and summer than in the late growing season. In summary, our results indicated that mowing would result in the imbalance of soil nutrients and intensify the risk of grassland degradation. In contrary, nitrogen addition exerted no effects on microbial biomass and activity.

Hydrogen peroxide suppresses TRPM4 trafficking to the apical membrane in mouse cortical collecting duct principal cells.

A Ca2+-activated nonselective cation channel (NSCCa) is found in principal cells of the mouse cortical collecting duct (CCD). However, the molecular identity of this channel remains unclear. We used mpkCCDc14 cells, a mouse CCD principal cell line, to determine whether NSCCa represents the transient receptor potential (TRP) channel, the melastatin subfamily 4 (TRPM4). A Ca2+-sensitive single-channel current was observed in inside-out patches excised from the apical membrane of mpkCCDc14 cells. Like TRPM4 channels found in other cell types, this channel has an equal permeability for Na+ and K+ and has a linear current-voltage relationship with a slope conductance of ~23 pS. The channel was inhibited by a specific TRPM4 inhibitor, 9-phenanthrol. Moreover, the frequency of observing this channel was dramatically decreased in TRPM4 knockdown mpkCCDc14 cells. Unlike those previously reported in other cell types, the TRPM4 in mpkCCDc14 cells was unable to be activated by hydrogen peroxide (H2O2). Conversely, after treatment with H2O2, TRPM4 density in the apical membrane of mpkCCDc14 cells was significantly decreased. The channel in intact cell-attached patches was activated by ionomycin (a Ca2+ ionophore), but not by ATP (a purinergic P2 receptor agonist). These data suggest that the NSCCa current previously described in CCD principal cells is actually carried through TRPM4 channels. However, the physiological role of this channel in the CCD remains to be further determined.

Ecological risk assessment of genetically modified crops based on cellular automata modeling.

The assessment of ecological risk in genetically modified (GM) biological systems is critically important for decision-making and public acceptance. Cellular automata (CA) provide a potential modeling and simulation framework for representing relationships and interspecies interactions both temporally and spatially. In this paper, a simple subsystem contains only four species: crop, target pest, non-target pest and enemy insect, and a three layer arrangement of LxL stochastic cellular automata with a periodic boundary were established. The simulation of this simplified system showed abundant and sufficient complexity in population assembly and densities, suggesting a prospective application in ecological risk assessment of GM crops.

[Therapeutic effects of koumine on psoriasis: an experimental study in mice].

OBJECTIVE: To study the therapeutic effects of koumine on psoriasis in mouse models. METHODS: The effects of koumine on epithelial cell mitosis and epidermal cell differentiation was evaluated by collecting the samples of the vaginal mucous and squamous epidermis at the tail of mice treated with methotrexate or koumine at different doses. The levels of interleukin (IL)-2 were detected with enzyme-linked immunosorbent assay. RESULTS: High and intermediate doses of koumine showed remarkable inhibitory effect on mouse vaginal epithelial cell mitosis and promoted the formation of epidermal granular layer in the scales at the mouse tail. Three concentrations at 6, 30, 150 mg/kg of koumine decreased serum IL-2 level in the mice. CONCLUSION: The therapeutic effect of koumine against psoriasis is related to the inhibition of epidermal cell proliferation, promoting the formation of granular cells and decreasing the serum level of IL-2.

[Effect of koumine on proliferation of murine CD4+ T cells purified by magnetic-activated cell sorting in vitro].

OBJECTIVE: To assess the separation efficiency of magnetic-activated cell sorting in the purification of CD4+ T cells from murine spleen, and observe the effects of koumine on the proliferation of the separated cells. METHODS: CD4+ T cells were isolated from murine spleen by magnetic-activated cell sorting (MiniMACS). Fluorescence-activated cell sortering was employed to determine the purity of CD4+ T cells before and after the separation procedure followed by evaluation of the cell viability using trypan blue staining. Concanavalin A- (ConA, 5 microg/ml) or phytahematoagglutinin (PHA,1 mg/ml)-induced murine T cells were treated with different concentrations of koumine (10-320 microg/ml), and their proliferation was determined by MTT colorimetry, and enzyme-linked immunosorbent assay was used to measure IL-2 level in the cell culture supernatant. RESULTS: The purity of CD4+ T cells reached (90.3+/-5.8)% after the purification with a cell viability of (94.9+/-3.6)%. Koumine (20-320 microg/ml) dose-dependently inhibited ConA- or PHA-induced proliferation of murine lymphocytes as compared with the controls (P<0.05). Koumine (20, 100, and 200 microg/ml) significantly decreased the level of IL-2 in comparison with the control group (P<0.05). CONCLUSIONS: CD4+ T cells of high purity can be obtained from murine spleen using MiniMACS without impairing the viability of the cells. Koumine significantly inhibits the proliferation of murine CD4+ T cells due to its immunosuppressive effect and inhibition of IL-2 secretion.

[Infrared spectrum and nuclear magnetic resonance analysis of the alkaloid extract of Gelsemium produced in east Guangdong province].

OBJECTIVE: To identify the structure of the alkaloid extract of Gelsemium from east Guangdong province of China. METHODS: Fourier transform infrared (FTIR) absorption spectrometry, hydrogen and carbon spectra of nuclear magnetic resonance (NMR) and distortionless enhancement by polarization transfer (DEPT) analysis were used for the structural identification of the alkaloid exstract of Gelsemium. RESULTS: The frequency, intensity and shape of the extract's characteristic peaks in infrared absorption spectra (4,000.0-400.0 cm(-1)) and (1)H NMR, (13)C NMR were recognized and compared. The molecular structure of the sample was consistent with the theoretically derived model. CONCLUSION: The extract is structurally identical to koumine, which may provide evidence for its safe clinical application and establishment of Chinese medicine fingerprint database of Gelsemium.

[Extraction and separation of koumine from Gelsemium alkaloids].

OBJECTIVE: To establish a method for isolating and identifying koumine. METHODS: Koumine was first extracted from Gelsemium alkaloids by using chloroform, which was further separated and purified by column chromatograph, and identified by thin-layer chromatography. RESULTS AND CONCLUSION: Koumine crystals were isolated and purified from Gelsemium alkaloids effectively.