The marriage of immunomodulatory, angiogenic, and osteogenic capabilities in a piezoelectric hydrogel tissue engineering scaffold for military medicine.

BACKGROUND: Most bone-related injuries to grassroots troops are caused by training or accidental injuries. To establish preventive measures to reduce all kinds of trauma and improve the combat effectiveness of grassroots troops, it is imperative to develop new strategies and scaffolds to promote bone regeneration. METHODS: In this study, a porous piezoelectric hydrogel bone scaffold was fabricated by incorporating polydopamine (PDA)-modified ceramic hydroxyapatite (PDA-hydroxyapatite, PHA) and PDA-modified barium titanate (PDA-BaTiO3, PBT) nanoparticles into a chitosan/gelatin (Cs/Gel) matrix. The physical and chemical properties of the Cs/Gel/PHA scaffold with 0-10 wt% PBT were analyzed. Cell and animal experiments were performed to characterize the immunomodulatory, angiogenic, and osteogenic capabilities of the piezoelectric hydrogel scaffold in vitro and in vivo. RESULTS: The incorporation of BaTiO3 into the scaffold improved its mechanical properties and increased self-generated electricity. Due to their endogenous piezoelectric stimulation and bioactive constituents, the as-prepared Cs/Gel/PHA/PBT hydrogels exhibited cytocompatibility as well as immunomodulatory, angiogenic, and osteogenic capabilities; they not only effectively induced macrophage polarization to M2 phenotype but also promoted the migration, tube formation, and angiogenic differentiation of human umbilical vein endothelial cells (HUVECs) and facilitated the migration, osteo-differentiation, and extracellular matrix (ECM) mineralization of MC3T3-E1 cells. The in vivo evaluations showed that these piezoelectric hydrogels with versatile capabilities significantly facilitated new bone formation in a rat large-sized cranial injury model. The underlying molecular mechanism can be partly attributed to the immunomodulation of the Cs/Gel/PHA/PBT hydrogels as shown via transcriptome sequencing analysis, and the PI3K/Akt signaling axis plays an important role in regulating macrophage M2 polarization. CONCLUSION: The piezoelectric Cs/Gel/PHA/PBT hydrogels developed here with favorable immunomodulation, angiogenesis, and osteogenesis functions may be used as a substitute in periosteum injuries, thereby offering the novel strategy of applying piezoelectric stimulation in bone tissue engineering for the enhancement of combat effectiveness in grassroots troops.

[Effects of Short-term Nitrogen Addition on Soil Organic Carbon Components in Robinia pseudoacacia L. Plantation].

Nitrogen (N) deposition in the context of human activities continuously affects the carbon cycle of ecosystems. The effect of N deposition on soil organic carbon is related to the differential responses of different carbon fractions. To investigate the changes in soil organic carbon fraction and its influencing factors in the context of short-term N deposition, four N addition gradients:0 (CK), 1.5 (N1), 3 (N2), and 6 (N3) g·(m2·a)-1 were set up in acacia plantations based on field N addition experiments, and the soil physicochemical properties, microbial biomass, and enzyme activities were measured in June and September. The results showed that:① exogenous N input reduced soil pH, promoted the increase in soluble organic carbon content, and increased soil nitrogen effectiveness. ② Short-term N addition significantly reduced soil organic carbon content, and the response of each component of organic carbon to N addition was different. Among them, the content of easily oxidized organic carbon was significantly reduced and reached the lowest value under the N2 treatment, with 54.4% and 48.2% reduction compared with that of the control, respectively, and the content of inert organic carbon increased, although the increase was not significant. Nitrogen addition reduced the soil carbon pool activity and improved the stability of the soil carbon pool. Soil carbon pool activity reached its lowest under the N3 and N2 treatments, with a decrease of 53.3% and 52.80%, respectively, compared to that of the control. ③Random forest modeling indicated that the soil microbial biomass stoichiometry ratio, microbial biomass carbon, and AP were the key factors driving the changes in soil organic carbon activity under short-term N addition, explaining 65.96% and 66.68% of the changes in oxidizable organic carbon and inert organic carbon, respectively. Structural equation modeling validated the results of the random forest modeling, and soil microbial biomass stoichiometric ratios significantly influenced carbon pool activity. Short-term nitrogen addition changed soil microbial biomass and its stoichiometric ratio in the acacia plantation forest mainly through two pathways, i.e., increasing soil nitrogen effectiveness and promoting soil acidification and inhibiting extracellular carbon hydrolase activity, thus changing the soil carbon fraction ratio and participating in the soil organic carbon cycling process.

Structural, spectroscopic, luminescence sensing and TD-DFT theoretical studies of a CuP2N-type complex.

Luminescent cuprous complexes are an important class of coordination compounds due to their relative abundance, low cost and ability to display excellent luminescence. The title heteroleptic cuprous complex, [2,2'-bis(diphenylphosphanyl)-1,1'-binaphthyl-κ2P,P'](2-phenylpyridine-κN)copper(I) hexafluoridophosphate, rac-[Cu(C44H32P2)(C11H9N)]PF6, conventionally abbreviated rac-[Cu(BINAP)(2-PhPy)]PF6 (I), where BINAP and 2-PhPy represent 2,2'-bis(diphenylphosphanyl)-1,1'-binaphthyl and 2-phenylpyridine, respectively, is described. In this complex, the asymmetric unit consists of a hexafluoridophosphate anion and a heteroleptic cuprous complex cation, in which the cuprous centre in a CuP2N coordination triangle is coordinated by two P atoms from the BINAP ligand and by one N atom from the 2-PhPy ligand. Time-dependent density functional theory (TD-DFT) calculations show that the UV-Vis absorption of I should be attributed to ligand-to-ligand charge transfer (LLCT) characteristic excited states. It was also found that the paper-based film of this complex exhibited obvious luminescence light-up sensing for pyridine.

[Mineralization Characteristics of Soil Organic Carbon and Its Relationship with Organic Carbon Components in Artificial Robinia pseudoacacia Forest in Loess Hilly Region].

In order to explore the characteristics of organic carbon mineralization and the variation law of organic carbon components of an artificial forest in a loess hilly area, an artificial Robinia pseudoacacia forest restored for 13 years and the adjacent slope farmland were selected as the research objects, and indoor culture experiments under three different temperature treatments (15, 25, and 35℃) were carried out. The results indicated that the mineralization rate of soil organic carbon decreased sharply at first and then stabilized. The cumulative release of organic carbon increased rapidly in the initial stage of culture and gradually slowed in the later stage. Soil organic carbon mineralization in sloping farmland was more sensitive to temperature change, and its temperature sensitivity coefficient Q10 was 1.52, whereas that in R. pseudoacacia forest land was only 1.38. According to the fitting of the single reservoir first-order dynamic equation, the soil mineralization potential Cp of R. pseudoacacia forest land and slope farmland was between 2.02-4.32 g·kg-1 and 1.25-3.17 g·kg-1, respectively, that is, the mineralization potential of the R. pseudoacacia forest was higher. During the cultivation period, the content of various active organic carbon components decreased with time, and that in the R. pseudoacacia forest land was greater than that in the slope land. The cumulative carbon release of soil was significantly positively correlated with the contents of MBC and DOC (P<0.05), and Q10 (15-25℃) was negatively correlated with the contents of SOC, EOC, and SWC (P<0.05). These results could provide some reference for the study of soil carbon sequestration in loess hilly regions under climate change.

[Establishment of High-Resolution Emissions Inventory in Wuhai and Its Application in Exploring the Causes of Ozone Pollution].

Wuhai is a typical coking industrial base including three industrial parks within its jurisdiction. The emission amount of air pollutants is considerable here, and O3 pollution has become serious in recent years. Clarifying the air pollutant emission characteristics and exploring the formation mechanism of O3 are the basis for objectively understanding the O3 pollution and formulating scientific prevention and control measures. This study established the high-resolution emission inventory of Wuhai in 2018 (HEI-WH18) based on the "coefficient method," evaluated the applicability and accuracy of HEI-WH18 using the WRF-Chem model, and explored the causes of O3 pollution in summer using WRF-Chem diagnosis module output. The HEI-WH18 showed that the total emissions amount of SO2, NOx, CO, PM10, PM2.5, VOCs, NH3, BC, and OC were 65943, 40934, 172867, 159771, 47469, 69191, 1407, 1491, and 1648 t·a-1, respectively. HEI-WH18 could capture the variation and magnitude of O3 and its precursors better than the MEIC, which was suitable for the O3 simulation and source analysis in summer. From the perspective of spatial distribution, Haibowan was a high-value area of O3 during the daytime, and the three industrial parks were low-value areas of O3 and high-value areas of NO2 during the daytime and nighttime. The spatial distribution characteristics of CO were consistent with the spontaneous combustion of coal and coal gangue sources. According to the diagnostic analysis of two O3 pollution processes, the O3 increase in the upper boundary layer was mainly related to the advection transport and chemical process, and it was caused by vertical mixing and the advection transport process in the lower boundary layer. The contribution of the chemical process in the lower boundary layer was complicated, and its positive contribution played a role in maintaining a high O3 concentration, whereas its negative contribution combined with advection transport resulted in the final dissipation of O3 pollution.

[Effects of Warming and Increased Precipitation on Soil Respiration of Abandoned Grassland in the Loess-Hilly Regions].

Clarifying the changing trends and driving factors of soil respiration in fragile habitats under the background of climate change is of great significance for understanding the regional carbon cycle and the conversion of ecosystem carbon source and sink functions. This research focused on grasslands that had been naturally abandoned and restored for 12 years in the loess hilly region of northern Shaanxi, using an open top chamber (OTC) and artificially increased natural rainfall to simulate climate warming and precipitation increase and their interaction. Furthermore, we used a combination of field monitoring and indoor analysis to explore soil water content, temperature, and nutrient characteristics and the response characteristics of soil respiration rate to warming and increased precipitation and further analyzed the key factors driving changes in soil respiration. The results showed that:① warming (W) significantly increased the 5 cm soil temperature, with an average increase of 1.34℃ throughout the sampling year, whereas the increased precipitation (P50%) treatment significantly reduced the 5 cm soil temperature, reducing the average 5 cm soil temperature during the entire sampling year by 0.88℃ and increasing the soil water content (SWC) at the same time. The SWC was 13.12% and 16.45% higher than that in the control (CK), respectively. In addition, compared with that in the CK, the treatment of warming and increased precipitation (WP50%) not only increased soil temperature but also increased SWC; in general, the increase in temperature and precipitation played an antagonistic effect on the influence of soil temperature and humidity. ② P50% significantly increased the content of soil organic carbon, dissolved organic carbon, and labile organic carbon, causing changes in the soil stoichiometric ratio and the distribution characteristics of labile-recalcitrant carbon components, whereas W did not have a significant impact on organic carbon. In addition, soil total nitrogen and phosphorus and available nitrogen and phosphorus nutrients were not significantly different between treatments. ③ P50% significantly increased the Rs rate, and the effect of W on the soil respiration rate mainly depended on the seasonal precipitation and temperature. It was demonstrated that warming in winter and seasons with abundant rainfall had a significant promotion effect on the soil respiration rate. The exponential fitting of soil respiration rate and 5 cm soil temperature found that the soil respiration temperature sensitivity (Q10) was the highest under the precipitation treatment, reaching 1.68, whereas the Q10 was the lowest under the warming treatment (1.50). ④ Linear regression analysis showed that soil organic carbon, dissolved organic carbon, and labile organic carbon were all significantly positively correlated with soil respiration rate. Variation partitioning analysis showed that soil temperature, SWC, and nutrient characteristics explained 64.43% of the variation in soil respiration rate. The soil temperature and SWC were the main controlling factors of the change in soil respiration rate, with an explanation degree of 31.16%. Correlation analysis also showed that there was a significant correlation between SWC, soil temperature and respiration rate, soil organic carbon, dissolved organic carbon, labile organic carbon, C:N, and C:P. In summary, the climate prediction of abandoned grassland tending toward warm temperatures and high humidity in the loess hilly region will significantly affect the regional hydrothermal environment and nutrient characteristics, change the distribution ratio of soil labile and recalcitrant carbon, and promote regional soil carbon emissions. The analysis results showed that the key factor driving the change in soil respiration rate of abandoned grassland in the loess hilly region was soil temperature and SWC characteristics.

[Improved Performance of PMF Source Apportionment for Volatile Organic Compounds Based on Classification of VOCs' Aging Degree in Air Mass].

VOCs are the key precursors of ozone and secondary organic aerosols. The results of source apportionment for VOCs are very important for the coordinated control of ozone and second organic particulate matter. However, VOCs do not fully meet the assumption of the receptor model because the VOCs released from each source are relatively unstable in the transmission process for their reactivity. As a result, we do not accurately obtain the actual source contribution when the receptor model is used for the source apportionment of VOCs. In order to solve the problem that the relative changes in the components caused by VOCs reactivity are not consistent with the PMF model hypothesis, the aging degree of VOCs was introduced to distinguish the state characteristics after their photochemical reactions in the ambient air. According to the ratio of ethylbenzene to m/p-xylene, VOCs monitored at Wuhai were divided into three aging states:high, medium, and low. The results showed that the model parameters, such as regression equation parameters (slope and intercept), standard error, determination coefficient, and pass rate of residual error, were improved obviously compared to the sample set after classification. Because the degree of aging is closely related to the transport time of air mass and the atmospheric oxidation in the atmosphere, it also reflects the different sources of air mass to some extent. In the high-aging VOCs samples, the coking source occupied a high proportion (up to 47.20%). In the low-aging VOCs samples, the combustion source and coking source accounted for a higher proportion, 28.67% and 24.39%, respectively. After the classification according to the aging degree, the results of VOCs source apportionment by PMF are more consistent with the actual contribution of emission sources.

Plant Biomass and Soil Nutrients Mainly Explain the Variation of Soil Microbial Communities During Secondary Succession on the Loess Plateau.

Soil microorganisms play an important role in the circulation of materials and nutrients between plants and soil ecosystems, but the drivers of microbial community composition and diversity remain uncertain in different vegetation restoration patterns. We studied soil physicochemical properties (i.e., soil moisture, bulk density, pH, soil nutrients, available nutrients), plant characteristics (i.e., Shannon index [HPlant] and Richness index [SPlant], litter biomass [LB], and fine root biomass [FRB]), and microbial variables (biomass, enzyme activity, diversity, and composition of bacterial and fungal communities) in different plant succession patterns (Robinia pseudoacacia [MF], Caragana korshinskii [SF], and grassland [GL]) on the Loess Plateau. The herb communities, soil microbial biomass, and enzyme activities were strongly affected by vegetation restoration, and soil bacterial and fungal communities were significantly different from each other at the sites. Correlation analysis showed that LB and FRB were significantly positively correlated with the Chao index of soil bacteria, soil microbial biomass, enzyme activities, Proteobacteria, Zygomycota, and Cercozoa, while negatively correlated with Actinobacteria and Basidiomycota. In addition, soil water content (SW), pH, and nutrients have important effects on the bacterial and fungal diversities, as well as Acidobacteria, Proteobacteria, Actinobacteria, Nitrospirae, Zygomycota, and microbial biomass. Furthermore, plant characteristics and soil properties modulated the composition and diversity of soil microorganisms, respectively. Overall, the relative contribution of vegetation and soil to the diversity and composition of soil bacterial and fungal communities illustrated that plant characteristics and soil properties may synergistically modulate soil microbial communities, and the composition and diversity of soil bacterial and fungal communities mainly depend on plant biomass and soil nutrients.

[Establishment of a High-resolution Anthropogenic Emission Inventory and Its Evaluation Using the WRF-Chem Model for Lanzhou].

City-scale high-resolution anthropogenic emission inventories are an important tool for ambient air quality forecasting and early warning, the analysis of underlying causes, and policy making. At present, city-scale anthropogenic emissions inventories for use in air quality models are scarce for West China. By studying the literature on emission inventories, this paper establishes a city-scale anthropogenic emission inventory for Lanzhou (HEI-LZ16) as the basis for an air quality model. The weather research and forecasting with chemistry (WRF-Chem) model was used to evaluate the applicability of the emission inventory at different resolutions in Lanzhou. The results showed that the emission amounts of SO2, NOx, CO, NH3, VOCs, PM10, PM2.5, BC, and OC in Lanzhou were 25642, 53998, 319003, 10475, 35289, 49250, 19822, 2476, and 1482 t·a-1 in 2016,respectively. Compared with the simulation scenario of multi-resolution emission inventory for China (MEIC), normalized mean error (NME) of O3 and PM2.5 under the HEI-LZ16 scenario decreased by 140.2% and 28.8%, respectively. The HEI-LZ16 inventory is more suitable for application in air pollution research in Lanzhou, which was verified by the WRF-Chem model and the observational data. The spatiotemporal distributions of PM2.5 and O3 were also analyzed using the HEI-LZ16 scenario. The ozone concentration of the maximum daily 8-h average (MDA8) in Lanzhou was low in urban areas and high in the suburbs during winter and spring, and high in the west of the urban valley and its downwind areas during summer and autumn. MDA8 in summer and autumn was influenced by easterly winds and photochemical reactions. In winter, ozone concentrations in urban areas are suppressed by NOx emissions but the concentration decreases. High PM2.5 concentrations are mainly concentrated within the Yellow River Valley. This study shows that there is a pollutant transmission channel along the western side of the Baiyin-Lanzhou Yellow River Valley, which has a greater impact on the ambient air quality in Lanzhou.

[Formation Potential of Ozone and Secondary Organic Aerosol of VOCs from Fossil Fuel Combustion in Lanzhou City].

With the rapid development of China's industry and the acceleration of urbanization, the massive use of fossil fuels has increased the concentration of air pollutants such as sulfur dioxide, particulate matter, and volatile organic compounds (VOCs) in the cities. However, there is little research on the environmental impact of volatile organic compounds from fossil fuel combustion emissions. In this paper, ozone formation potential(OFP)and secondary organic aerosol formation potential (SOAFP) of VOCs from fossil fuel combustion in Lanzhou city were calculated. The OFP and SOAFP of the cement industry were the largest, representing 45.3% and 50.9%, respectively, followed by brick and tile industries. However, when the calculations were based on tons of standard coal equivalent, the largest contributors to OFP and SOAFP of VOCs emitted from combustion were the brick and tile industries, and the smallest was the natural gas industry. VOCs from fossil fuel combustion of power plants and industry enterprises in the Xigu District are the main contributors to the OFP and SOAFP in the urban district of Lanzhou city. The contribution rates of the aromatic hydrocarbons from fossil fuel to OFP and SOAFP account for 40.0% and 67.2%, respectively. Aromatic hydrocarbons are also the main component in the top 10 species that contribute to OFP and SOAFP. The mass ratio of OFP and SOAFP per VOCs from fossil fuel combustion (2.58 t·t-1, 3.16 kg·t-1) is larger than those from biomass combustion (2.22 t·t-1, 1.38 kg·t-1).

[Inventory and Spatiotemporal Distribution of Ammonia Emission from Agriculture and Animal Husbandry in Lanzhou City].

After obtaining data on the activity of agriculture and animal husbandry by field investigation and from statistical data, an inventory of ammonia emission from agriculture and animal husbandry in Lanzhou was established based on literature investigation to determine the emission factors. The emission factor related to the application of nitrogen fertilizer was calculated using the NARSES model. The spatiotemporal distribution of the amount of ammonia emission was also analyzed. The total amount of ammonia emission from agriculture and animal husbandry was 9356.90 t. Among this emission, the amount from livestock and poultry was 7584.03 t, accounting for 81.05%. Yongdeng County was the region with the largest amount of ammonia emission, which was 2820.59 t, accounting for 30.14%. Considering the sharing rate of ammonia emissions in all districts and counties, the sharing rates of livestock and poultry were between 65.83% and 97.38%; and the sharing rates for nitrogen fertilizer application were between 2.27% and 28.66%. From the perspective of spatial distribution, the sources of ammonia emissions from agriculture and animal husbandry were mainly concentrated in the northwest and central parts of Gaolan County, the southeast of Honggu District, the east and west of Qilihe District, and the east of Yuzhong County. From the perspective of temporal distribution, the ammonia emissions from livestock and poultry were higher from April to September. The emission from nitrogen fertilizer application was higher from March to September, except in August.

[Emissions Inventory of Smoldering Chinese Kangs and Their Contribution to PM2.5 Pollution in Lanzhou City].

Considering regional differences in economic development, the activity level of smoldering Chinese kangs was confirmed by surveys in typical areas in Lanzhou City. An emissions inventory of smoldering Chinese kangs in Lanzhou City in 2016 was established using the emissions factor approach. The emissions amounts of SO2, NOx, NH3, CO, volatile organic compounds (VOCs), PM10, PM2.5, organic carbon (OC) and elemental carbon (EC) were 340.8, 201.8, 106.0, 36628.2, 4997.2, 6070.3, 5645.1, 1089.3, and 1233.1 t·a-1, respectively. Emissions amounts were allocated by spatial and temporal characteristics. The emissions were concentrated from November to mid-April of the following year. Spatially, there were significant differences in emissions at different economic levels. The high value areas of emissions were mainly concentrated in the southern part of Yuzhong, central Yongdeng, and south of Qilihe. The weather research and forecasting with chemistry (WRF-Chem) model was used to determine the average contribution of smoldering Chinese kangs to PM2.5 concentration in Lanzhou City during the heating season. The simulation results were improved after applying the emissions inventory. The average PM2.5 concentration at Lanyuan Hotel (in the city) and Yuzhong Station (in the countryside) increased 32 µg·m-3 and 34 µg·m-3 in the simulation, respectively, and the corresponding rates of pollution contribution were 37.6% and 49.2%. Thus, researching and enacting scientific control measures for smoldering Chinese kang pollutants is significant to improving regional air quality.