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Nitrogen (N) and phosphorous (P) fertilizer management is an effective approach to improve grasslands and feed quality following grassland degradation; however, it is still unclear how N and P fertilizer management affects soil nematodes and how this leads to changes in vegetation production. This study investigated the responses of vegetation and soil nematode communities to a 9-year fertilization (N and P) experiment in an alpine grassland in the Qinghai–Tibetan Plateau, China. The results indicated that N fertilizer significantly increased the abundance of plant parasites, whereas P fertilizer had a notably positive effect on fungivorous nematodes compared to nitrogen fertilization. The abundance of fungivorous nematodes increased following P fertilization, but the increase was not statistically significant. N fertilizer significantly reduced bacterivorous carbon biomass and the metabolic footprint of bacterivorous nematodes, while the suppressive effect of P fertilizer and N + P fertilizer on the carbon flux of bacterial channels was significantly greater than that of N fertilization alone. The functional metabolic footprints of N and P fertilizers were significantly lower than those of the unfertilized plot (CK). N fertilizer is detrimental to the increase in vegetation production following grazing prohibition, as it is mediated by the increase of plant parasite nematodes. P fertilizer, by influencing the abundance of bacterivorous and fungivorous nematodes, benefits the production of grassland ecosystems. This is because P fertilizer inhibits carbon from entering the soil food web, thereby maintaining the carbon content in above-ground biomass. Therefore, a certain level of P addition positively contributes to the recovery of above-ground productivity.

Resource enhancements have been shown to affect ecosystem functions that are central to biogeochemical cycling. However, knowledge gaps still remain regarding how changes in soil microbial communities are impacted by long-term fertilization and the influence of long-term fertilization on agroecosystem multifunctionality, and the mechanism how the shifts of soil microbial community drives agroecosystem functions and ultimately yields. We chose buckwheat (Fagopyrum esculentumMoench.) to evaluate how agroecosystem functions in terms of element cycles driven by soil microbial communities finally impact yields, with seven fertilizer applications: control with no fertilizer (CK); nitrogen (N); phosphorus (P); N and P (NP); manure (M); M and N (MN); and M, N, and P (MNP) since 1983 in the Loess Plateau, China. Yields at MNP were significantly higher than that of other treatments. The threshold elemental C:N ratio was higher, in comparison to the C:N of soil from each treatment, whereas the threshold elemental ratio of C:P was lower than the soil C:P from each treatment, suggesting that the microbes were suppressed by C and P. This equilibrium of microbial nutrient demands and soil resource supplementation was balanced by increasing the alkaline phosphatase (AP) and β-1,4-glucosidase (BG) activity (range: 71.89 to 117.11, and 782.14 to 1164.58 nmol g− 1h− 1, respectively). In addition, fertilizer application impacted soil total and bacterial phospholipid fatty acid (PLFA) contents. MN and MNP promoted the multifunctionality and element cycling (C, N, and P) in soil ecosystem. And soil multifunctionality and P cycling index was positively linked with soil microbial community composition. From structural equation model, both soil microbial C and P limitation state altered soil total PLFA, thus affecting C cycles and yield.

Microplastics (MPs) pollution and dissolved organic matter (DOM) affect soil quality and functions. However, the effect of MPs on DOM and underlying mechanisms have not been clarified, which poses a challenge to maintaining soil health. Under environmentally relevant conditions, we evaluated the major role of polypropylene particles at four micron-level sizes (20, 200, and 500 μm and mixed) in regulating changes in soil DOM content. We found that an increase in soil aeration by medium and high-intensity (>0.5%) MPs may reduce NH4+leaching by accelerating soil nitrification. However, MPs have a positive effect on soil nutrient retention through the adsorption of PO43–(13.30–34.46%) and NH4+(9.03–19.65%) and their leached dissolved organic carbon (MP-leached dissolved organic carbon, MP-DOC), thereby maintaining the dynamic balance of soil nutrients. The regulating ion (Ca2+) is also an important competitor in the MP-DOM adsorption system, and changes in its intensity are dynamically involved in the adsorption process. These findings can help predict the response of soil processes, especially nutrient cycling, to persistent anthropogenic stressors, improve risk management policies on MPs, and facilitate the protection of soil health and function, especially in future agricultural contexts.

Global warming has increasingly detrimental impacts on the structure and function of the Tibetan Plateau ecosystem. However, the mechanism by which warming affects the biogeochemical processes, and consequently the microbial nutrient limitation in soil aggregates, is not clear. In this study, we implemented a 21-year long-term open-top-chamber (OTCs) warming experiment to reveal the warming effects on the soil aggregate microbial nutrient limitation mechanisms in a Tibetan alpine meadow and shrubland. Long-term warming significantly decreased soil aggregate-associated organic carbon (SOC) and total nitrogen (TN) concentrations in alpine meadows, but promoted soil carbon pool in alpine shrublands. SOC and TN concentrations in microaggregate (MIGA: < 0.25 mm) showed the greatest in alpine meadows. Soil enzyme activities increased with the decrease in aggregate size, and enzyme stoichiometry results demonstrated that soil microbes in alpine meadows and shrubland were limited by phosphorus (P); moreover, the long-term warming significantly aggravated the soil aggregate microbial P limitation in the shrubland. Meanwhile, the long-term warming had no significant effect on microbial C limitation in the alpine meadow and shrubland, but soil aggregate size mediated the microbial C limitation patterns and showed the greatest C limitation in MIGA. Phosphorus limitation is likely to be an important constraint to the development of alpine ecosystems in future climate warming, and the protection of MIGA is one of the important mechanisms for carbon pool sequestration.

Distinguishing between Alzheimer’s disease (AD) and frontotemporal dementia (FTD) presents a clinical challenge. Inexpensive and accessible techniques such as electroencephalography (EEG) are increasingly being used to address this challenge. In particular, the potential relevance between aperiodic components of EEG activity and these disorders has gained interest as our understanding evolves. This study aims to determine the differences in aperiodic activity between AD and FTD and evaluate its potential for distinguishing between the two disorders. A total of 88 participants, including 36 patients with AD, 23 patients with FTD, and 29 healthy controls (CN) underwent cognitive assessment and scalp EEG acquisition. Neuronal power spectra were parameterized to decompose the EEG spectrum, enabling comparison of group differences in different components. A support vector machine was employed to assess the impact of aperiodic parameters on the differential diagnosis. Compared with the CN group, both the AD and FTD groups showed varying degrees of increased alpha power (both periodic and raw power) and theta alpha power ratio. At the channel level, theta power (both periodic and raw power) in the frontal regions was higher in the AD group compared to the FTD group, and aperiodic parameters (both exponents and offsets) in the frontal, temporal, central, and parietal regions were higher in the AD group than in the FTD group. Importantly, the inclusion of aperiodic parameters led to improved performance in distinguishing between the two disorders. These findings highlight the significance of aperiodic components in discriminating dementia-related diseases.

Mitochondrial dysfunction leads to impaired intestinal barrier function. Natural agents can improve mitochondrial function and increase intestinal barrier function. In this study, we investigated the effect of kiwifruit polyphenols (KP) on lipopolysaccharide (LPS)-induced intestinal permeability in Caco-2 cells and animal models. KP treatment increased trans-epithelial electrical resistance (TER) values and tight junction protein expression, while decreasing FD4 flux. Mechanistically, KP supplementation induced upregulation of 53 proteins and downregulation of 55 proteins, related to oxidative phosphorylation, mitophagy, AMPK-signaling pathway, the tricarboxylic acid cycle, etc. Concomitant with improved mitochondrial morphology, downregulated mitophagy and AMPK and ULK2 expression. Activation of AMPK by AICAR increased the permeability of Caco-2, while KP increased the TER value, improved mitophagy, and downregulated AMPK and ULK2. In LPS-stressed rats, KP improved colonic epithelial cells' tight junction integrity, reduced mitophagy, as well as AMPK and ULK2 expression. In conclusion, KP promotes intestinal barrier by inhibiting AMPK/ULK2-induced mitophagy.

Objective: To explore the anti-inflammatory effects and mechanisms of action of thymol in Aspergillus fumigatus(A. fumigatus) keratitis. Methods: The minimum inhibitory concentration of thymol against A. fumigatuswas detected. To characterize the anti-inflammatory effects of thymol, mouse corneas and human corneal epithelial cells were pretreated with thymol or dimethyl sulfoxide (DMSO) before infection with A. fumigatusspores. Slit-lamp microscopy, immunohistochemistry, myeloperoxidase detection, quantitative real-time polymerase chain reaction, and Western blotting were used to assess infection. Neutrophil and macrophage recruitment, in addition to the secretion of LOX-1 and IL-1β, were quantified to evaluate the relative contribution of thymol to the inflammatory response. Results: We confirmed that the growth of A. fumigatuswas directly inhibited by thymol. In contrast with the DMSO group, there was a lower degree of inflammation in the mouse corneas of the thymol-pretreated group. This was characterized by significantly lower clinical scores, less inflammatory cell infiltration, and lower expression of LOX-1 and IL-1β. Similarly, in vitroexperiments indicated that the production of LOX-1 and IL-1β was significantly inhibited after thymol treatment, in contrast with the DMSO-pretreated group. Conclusion: Our findings demonstrate that thymol exerted a direct fungistatic activity on A. fumigatus. Furthermore, thymol played a protective role in fungal keratitis by inhibiting LOX-1/IL-1β signaling pathway and reducing the recruitment of neutrophils and macrophages.

Exotic species invasion represent important causes of harming the structure, function, and ecological environment in ecosystems. Yet, knowledge remains limited on the invasibility (invasion advantage of exotic species) and recoverability (recovery ability of native species) of a plant community following invasion depend on its successional stages. We selected three grasses of Setaria viridis, Artemisia gmelinii, and Bothriochloa ischemumrepresenting early (E), middle (M), and late (L) successional species, respectively. Meanwhile, the grasses of Panicum virgatumwas selected to represent exotic species (invasion species). Three types of soil were collected to treat the three E, M, and L successional species, and one type of soil was collected to treat the exotic species. We compared the performance of the three native plant species and one exotic species grown in their “own” and “other” soils in a 2-year greenhouse experiment. Our study showed that exotic species performed better in soils of E and M successional species than in the soil of L successional species. After exotic species removed, E and M successional species exhibited poor growth in the soil of exotic species, while that of L successional species performed poor in field exotic species soils, but performed better in soils disturbed by exotic species. Our study demonstrated that the invasibility and recoverability of native plant communities changed with vegetation succession.

Microbes play an important role in the carbon cycle and nutrient flow of the soil ecosystem. However, the response of microbial activities to long-term warming over decades is poorly understood. To determine how warming changes ecoenzyme activity and microbial nutrient limitation, we conducted a long-term, 21 years, experiment, on the Qinghai—Tibet Plateau. We selected typical grass- and shrub-covered plots, used fiberglass open-top chambers (OTCs) to raise the temperature, conducted soil sampling at different depths, studied the response of nutrient-acquiring enzyme activity and stoichiometry, and conducted vector analysis of stoichiometry. Our results showed that long-term warming did not have a notable effect on the activity of nutrient-acquiring enzymes or enzymatic stoichiometry. However, Spearman correlation analysis indicated a significant and positive correlation between ecoenzyme activity and the available nutrients and microbial biomass in soil. Vector analysis of stoichiometry showed phosphorus limitation for all soil microbes at different depths, regardless of whether the soil experienced warming. These changes in enzymatic stoichiometry and vector analysis suggested that microbial nutrient limitation was not alleviated substantially by long-term warming, and warming did not considerably affect the stratification of microbial nutrient limitation. Our research has also shown that long-term warming does not significantly change soil ecoenzyme activity and original microbial nutrient limitation at different soil depths within the OTUs’ impact range. These results could help improve understanding of microbial thermal acclimation and response to future long-term global warming.

Nitrogen (N) deposition, the source of N input into terrestrial ecosystems, is exhibiting an increasingly serious impact on the biogeochemical cycle and functional stability of ecosystems. Grasslands are an important component of terrestrial ecosystems and play a key role in maintaining terrestrial ecosystem balance. Therefore, it is critical to understand the effects of nitrogen addition on grassland ecosystems. We conducted gradient N addition experiments (0, 3, 6, and 9 g N m−2y−1) for three years in grassland communities with similar site conditions. We utilized four typical herbaceous plants, including the dominant species Bothriochloa ischemum(B. ischemum) and companion species Stipa bungeana(S. bungeana), Artemisia gmelinii(A. gmelinii), and Cleistogenes squarrosa(C. squarrosa), to explore how different plant-soil-microbe systems respond to N addition. Stoichiometric homeostasis analysis demonstrated that both plants and microbes were strictly homeostatic. However, the companion species were found to be more susceptible to P dominant species. Furthermore, aggravated overlap in stoichiometric niches between plant species were observed at the N6 and N9 levels. Vector analysis indicated that the vector angle was >45° regardless of plant species and N levels, suggesting that there was a strong P limitation in the rhizosphere microbial community. Variation partitioning analysis revealed that the Composite roots exhibited a greater effect (explaining 34.7% of the variation) on the rhizosphere microbes than on the Gramineae, indicating that there may be more intense nutrient competition in its rhizosphere. In general, the effects of N addition on species were different across functional groups, with asignificant positive effect on the Gramineae (B. ischemum, S. bungeana,and C. squarrosa) and a significant negative effect on the Compositae (A. gmelinii), which should be fully considered in the future ecological management and restoration.

Objective This study was performed to evaluate the clinical efficacy of subcostal thoracoscopy and median sternotomy as surgical approaches for thymoma resection and lymph node dissection. The feasibility, safety, and clinical outcomes of subcostal thoracoscopy were compared with those of median sternotomy.Methods The clinical data of 335 patients with thymoma were retrospectively analyzed. The patients were divided into the subcostal thoracoscopy group and the median sternotomy group. Propensity score matching was performed to obtain comparable subsets of 50 patients in each group. A comparative analysis was conducted on various parameters.Results All surgeries were successful, and no conversions to open thoracotomy were required in the subcostal thoracoscopy group. Significant differences in the operative time, intraoperative blood loss, chest tube drainage duration, postoperative hospital stay, patient satisfaction scores, pain assessment, and postoperative complications were observed between the two groups. However, there was no significant difference in the number of lymph nodes or lymph node stations dissected intraoperatively between the two groups.Conclusion Subcostal thoracoscopy is not inferior to median sternotomy as a surgical approach for thymoma resection and lymph node dissection. Our research provides important new comparative data on minimally invasive thymoma resection.

Increased atmospheric nitrogen (N) deposition caused by human activities has potentially important effects on ecosystem carbon (C) dynamics and different effects on C fractions with different stabilities and chemical compositions. A better understanding of the responses of different C fractions to N addition is vital for maintaining soil quality and protecting vegetation. In order to investigate the differential effects of N addition on total soil organic carbon (SOC) and four SOC fractions with increasing degrees of oxidisability in Pinus tabuliformis rhizospheric and bulk soils, a 6-year pot experiment was performed testing the effects of the addition of N at rates of 2.8, 5.6, 11.2, 22.4 and 44.8g m-2 year-1 compared with a control (CK) group (no N addition). Addition of N addition had significant (P<0.05) effects on SOC fractions of very labile C (C1) and recalcitrant C (C4), but negligible effects on total SOC (TOC) and SOC fractions of labile C (C2) and less labile C (C3). The C1 content and ratio of C1 to TOC in rhizospheres decreased following the addition of low levels (N2.8–N5.6) of N, but increased after the addition of high levels (N11.2–N44.8) of N, with minimum values obtained after the addition of 11.2N g m-2 year-1. Low rates (N2.8–N5.6) of N addition considerably increased C4 and the ratio of C4 to TOC in the rhizosphere, whereas addition of high rates (N11.2–N44.8) of N decreased these parameters. The responses of C1 and C4 in the bulk soil to N addition were opposite. The SOC fraction was significantly higher in the rhizosphere than in the bulk soil, indicating large rhizospheric effects. However, increased N addition weakened these effects. These findings suggest that low rates (N2.8–N5.6) of N addition stabilise SOC against chemical and biological degradation, whereas increased rates of N addition increase the lability of SOC in the bulk soil. Thus, the rhizosphere plays a vital role in soil carbon stability and sequestration in response to N addition.

Curcumin has been widely used as a food additive for centuries and has been recently explored for its anti-inflammatory and antitumor properties. Although curcumin is pharmacologically safe and efficacious to certain cancers, its role against acute myeloid leukemia (AML) still remains unclear, and it lacks clinical application due to low water solubility and low in vivobioavailability. To address these issues, we developed a novel curcumin liposome modified with hyaluronan (HA-Cur-LPs) to specifically deliver curcumin to AML by targeting CD44 on AML cell surface. When compared with free curcumin and nontargeted liposome (Cur-LPs), the HA-Cur-LPs exhibited good stability, high affinity to CD44, increased cellular uptake, and more potent activity on inhibiting AML cell proliferation. The KG-1 cell implanted AML mice had significantly delayed, or even prevented, AML progression following treatment with 50 mg/kg of curcumin dose in the HA-Cur-LPs every 2 days for 2 weeks. Mechanistically, the anti-AML effects of HA-Cur-LPs were achieved by inhibiting Akt/ERK pathways and activating caspase-dependent apoptosis. Moreover, HA-Cur-LPs played a critical role in downregulation of DNMT1 expression in AML, leading to DNA hypomethylation and reactivation of tumor suppressor genes such as miR-223. The development and assessment of the HA-Cur-LPs in this study provide another potential choice for AML therapy, using HA-Cur-LPs as either a single treatment agent or in combination with other treatments.

Secondary succession is the process by which a community develops into a climax community over time. However, knowledge on the mechanisms, relating to soil legacy effects (soil chemistry and enzyme activity) and plant—soil feedback (PSF), driving community succession remains limited. In this work, we examined the PSF associated with three succession stage species through a 2-year greenhouse experiment. Setaria viridis, Stipa bungeana, and Bothriochloa ischemumwere selected to represent dominant and representative early-, mid-, and late-successional stage species, respectively, of semiarid grasslands on the Loess Plateau. In response to the different soil origin, the shoot biomass of early-, mid-, and late-species were all higher when grown in their own soil than in other species’ soils, which indicated that the PSF of three species were positive. Over two growth periods, the early-species experienced a negative PSF, but the mid- and late-species experienced negative, neutral and positive PSF in the soil of early-, mid- and late-species, respectively. Our study demonstrates that soil legacy effects and PSF have a significant impact on community succession processes.

The effects of long-term fertilization on pools of soil organic carbon (SOC) have been well studied, but limited information is available on the oxidizable organic carbon (OOC) fractions, especially for the Loess Plateau in China. We evaluated the effects of a 15-year fertilization on the OOC fractions (F1, F2, F3 and F4) in the 0–20 and 20–40 cm soil layers in flat farmland under nine treatments (N (nitrogen, urea), P (phosphorus, monocalcium phosphate), M (organic fertilizer, composted sheep manure), N+P (NP), M+N (MN), M+P (MP), M+N+P (MNP), CK (control, no fertilizer) and bare land (BL, no crops or fertilizer)). SOC content increased more markedly in the treatment containing manure than in those with inorganic fertilizers alone. F1, F2, F4 and F3 accounted for 47%, 27%, 18% and 8% of total organic carbon, respectively. F1 was a more sensitive index than the other C fractions in the sensitivity index (SI) analysis. F1 and F2 were highly correlated with total nitrogen (TN) and available nitrogen (AN), F3 was negatively correlated with pH and F4 was correlated with TN. A cluster analysis showed that the treatments containing manure formed one group, and the other treatments formed another group, which indicated the different effects of fertilization on soil properties. Long-term fertilization with inorganic fertilizer increased the F4 fraction while manure fertilizer not only increased labile fractions (F1) in a short time, but also increased passive fraction (F4) over a longer term. The mixed fertilizer mainly affected F3 fraction. The study demonstrated that manure fertilizer was recommended to use in the farmland on the Loess Plateau for the long-term sustainability of agriculture.

The oxidizability of soil organic carbon (SOC) influences soil quality and carbon sequestration. Four fractions of oxidizable organic carbon (very labile (C1), labile (C2), less labile (C3) and non-labile (C4)) reflect the status and composition of SOC and have implications for the change and retention of SOC. Studies of the fractions of oxidizable organic carbon (OC) have been limited to shallow soil depths and agroecosystems. How these fractions respond at deep soil depths and in other types of land-use is not clear. In this study, we evaluated the vertical distributions of the fractions of oxidizable organic carbon to a soil depth of 5.0 m in 10 land-use types in the Zhifanggou Watershed on the Loess Plateau, China. Along the soil profile, C1contents were highly variable in the natural grassland and shrubland I (Caragana microphylla), C2and C4contents were highly variable in the natural grassland and two terraced croplands, respectively, and C3contents varied little. Among the land-use types, natural grassland had the highest C1and C2contents in the 0–0.4 m layers, followed by shrubland I in the 0–0.1 m layer. Natural grassland had the highest C4contents in the 1.0–4.5 m layers. Natural grassland and shrubland I thus contributed to improve the oxidizability of SOC in shallow soil, and the deep soil of natural grassland has a large potential to sequester SOC on the Loess Plateau.

Fractal theory is becoming an increasingly useful tool to describe soil structure dynamics for a better understanding of the performance of soil systems. Changes in land use patterns significantly affect soil physical, chemical and biological properties. However, limited information is available on the fractal characteristics of deep soil layers under different land use patterns. In this study, the fractal dimensions of particle size distribution (PSD) and micro-aggregates in the 0–500 cm soil profile and soil anti-erodibility in the 0–10 cm soil profile for 10 typical land use patterns were investigated in the Zhifanggou Watershed on the Loess Plateau, China. The 10 typical land use patterns were: slope cropland, two terraced croplands, check-dam cropland, woodland, two shrublands, orchard, artificial and natural grasslands. The results showed that the fractal dimensions of PSD and micro-aggregates were all significantly influenced by soil depths, land use patterns and their interaction. The plantations of shrubland, woodland and natural grassland increased the amount of larger micro-aggregates, and decreased the fractal dimensions of micro-aggregates in the 0–40 cm soil profile. And they also improved the aggregate state and aggregate degree and decreased dispersion rate in the 0–10 cm soil profile. The results indicated that fractal theory can be used to characterize soil structure under different land use patterns and fractal dimensions of micro-aggregates were more effective in this regard. The natural grassland may be the best choice for improving soil structure in the study area.

Grassland is a major carbon sink in the terrestrial ecosystem. The dynamics of grassland carbon stock profoundly influence the global carbon cycle. In the published literatures so far, however, there are limited studies on the long-term dynamics and influential factors of grassland carbon stock, including soil organic carbon. In this study, spatial-temporal substitution method was applied to explore the characteristics of Medicago sativa L. (alfalfa) grassland biomass carbon and soil organic carbon density (SOCD) in a loess hilly region with different growing years and management patterns. The results demonstrated that alfalfa was the mono-dominant community during the cutting period (viz. 0–10 year). Community succession began after the abandonment of alfalfa grassland and then the important value of alfalfa in the community declined. The artificial alfalfa community abandoned for 30 years was replaced by the S. bungeanacommunity. Accordingly, the biomass carbon density of the clipped alfalfa showed a significant increase over the time during 0–10 year. During 0–30 year, the SOCD from 0–100 cm of the soil layer of all 5 management patterns increased over time with a range between 5.300 ± 0.981 kg/m2and 12.578 ± 0.863 kg/m2. The sloping croplands had the lowest SOCD at 5.300 ± 0.981 kg/m2which was quite different from the abandoned grasslands growing for 30 years which exhibited the highest SOCD with 12.578 ± 0.863 kg/m2. The ecosystem carbon density of the grassland clipped for 2 years increased 0.1 kg/m2compared with the sloping cropland, while that of the grassland clipped for 10 years substantially increased to 10.30 ± 1.26 kg/m2. Moreover, the ecosystem carbon density for abandoned grassland became 12.62 ± 0.50 kg/m2at 30 years. The carbon density of the grassland undisturbed for 10 years was similar to that of the sloping cropland and the grassland clipped for 2 years. Different management patterns imposed great different effects on the accumulation of biomass carbon on artificial grasslands, whereas the ecosystem carbon density of the grassland showed a slight increase from the clipping to abandonment of grassland in general.

Global and local image retrieval of ancient Chinese characters is a helpful means for character research work. Because of the characteristics of ancient Chinese characters such as complex structures and variant shapes, there exist many theoretical and technical problems in feature extraction, clustering and retrieval of these images. A retrieval method was established with the strategy of “clustering before matching” for the ancient Chinese character images by integrating the structural features of them. Firstly, preprocessed character image area was divided into elastic meshes and the directional elements were extracted to form the feature vectors. Then, K-means algorithm was employed to cluster the character images within global and local areas. Finally, the similar images within selected areas were searched in corresponding cluster and the obtained images were provided to users. The experimental results show that this method is helpful for the improvement of the efficiency of ancient Chinese character study.

The re-establishment of natural species-rich health lands on abandoned farmland is one of the main measures in soil erosion control in the Loess Plateau of China. This study was conducted to understand how enzyme activities changed with nutritional properties and microbial biomass in different vegetation types in the loessial gully region of the Loess Plateau. Soil samples were collected in different vegetations which had planted for almost 30 years. For the collected soils, nutritional, microbial and enzymatic properties were determined. The result showed that soil nutritional properties and microbial biomass were enhanced in black locust-amorpha, compared with black locust, but weakened in Chinese pine-amorpha compared with Chinese pine. Besides, soil urease, α-amylase, alkaline phosphatase, catalase, saccharase and cellulase activities in creased with restoration, but decreased polyphenol oxidase. Moreover, urease activity was obviously high in korshinsk peashrub and black locust for the nitrogen fixation of them, and α-amylase was high in Chinese pine for low pH value. However, there still was a certain gap to Chinese arborvitae which was considered to be the climax community in the region. In general, the distance of vegetations to Chinese arborvitae was grassland > black locust > Chinese pine> korshinsk peashrub > Chinese pine-amorpha > black locust-amorpha.

Rational fertilization is the guarantee for the productivity and stability of crop and sustainable development of rain-fed agriculture. In this study, based on a long term fertilization experiment initiated in 1984, we researched the effect of different fertilizer application on soil water profile distribution and water use efficiency (WUE) from 1999 to 2010. The experimental design consisted a control treatment (CK) and eight fertilizer treatments: farmyard manure (M), farmyard manure and nitrogen (MN), farmyard manure and phosphorus (MP), nitrogen and phosphorus (NP), nitrogen, phosphorus and farmyard manure (NPM), nitrogen and potassium (NK), phosphorus and potassium (PK), nitrogen, potassium and potassium (NPK). Soil moisture content of MN, MP, MNP, M, and NP were significantly lower than Ck in 10-130 cm, while NPK and NK was only slightly lower than Ck. Compared with the CK, on average, treatments MNP and NPK increased the yield of crop by 259% and 226% and they also increased the crop WUE by 202% and 176%, respectively. The results indicated that the fertilizer application of NPK might be the best choice for the sustainable development of arid land agriculture on the Loess Plateau of China.

The different chemical and biological properties of the rhizosphere affect metal speciation in the soil, which in turn affects metal bioavailability. Changes in the rhizosphere accumulation of trace elements by plants may affect natural succession. This study investigated the effects of rhizosphere and bulk soils over time on available trace element (Mn, Fe, Cu, and Zn) concentrations in abandoned croplands at the Dunshan watershed in the Loess Plateau. Results showed that trace element accumulation depends on plant species, soil condition, and successional stage. The trace elements exhibited different responses to plant root presence. During the succession on the abandoned croplands in the Loess Plateau, organic C, total N, and available Zn concentrations in the rhizospheres increased compared with those in the bulk soil, whereas the pH and available Mn concentration decreased. The dominant species showed higher rhizosphere organic C, total N, available Mn, available Fe, and available Zn concentrations than the companion species. The concentrations of available Mn, Fe, and Zn in the rhizosphere of the early successional species Artemisia capillariesThunb showed no detectable age-related tendency. In contrast, the concentrations of available Cu, Fe, and Zn in the rhizosphere of the later species Artemisia sacrorumLedeb increased with years since abandonment. Correlation and regression analyses indicated that trace element accumulation is closely associated with organic C and total N concentrations for the later successional species, and increased organic C and total N concentrations can enhance its absorption of the trace elements.

Abandoning cropland to enable recovery of the natural vegetation has been implemented during the past decade to restore the soil quality in the Loess Plateau, China. However, natural succession on cropland in the different slope aspect is different. The present study aimed at investigating the change in soil chemical and microbial properties abandoned farmland across time, and also to compare the difference of soil chemical and microbial properties in north slope and south slope on the Loess Plateau. The results showed that the slope aspect greatly affected the soil chemical and microbial properties after the cropland was abandoned, this could be attributed to the different precipitation and temperature in the two slopes. Compared with the north slope in which the organic C, total N and available N increased with the increase of abandonment years, that of south slope fluctuated significantly. Microbial biomass C and microbial biomass N in both slopes did not differ significantly in the first 10 years abandoned cropland, then decreased drastically in 15-year sites and thereafter tended to increase. Basal respiration in both slope fluctuated greatly in the sites with different abandonment years. Enzymes activities differed significantly in two slopes.

In order to satisfy the revamping of refinery and chemical equipments, a new kind of tray, enhanced jet tray (EJT), was presented. The hydrodynamic and mass transfer performances of EJT and new vertical sieve tray (New VST) were investigated with air-water-oxygen system in a stainless steel column of 1200mm internal diameter. Correlations of hydrodynamic parameters such as pressure drop, weeping and entrainment of EJT were obtained. The experimental results show that EJT has lower pressure drop, fractional weeping, entrainment and higher efficiency compared with New VST because of its special geometry characteristics.

Breaking time reversal symmetry in a topological insulator may lead to quantum anomalous Hall effect and axion insulator phase. MnBi4Te7is a recently discovered antiferromagnetic topological insulator with TN∼ 12.5 K, which is composed of an alternatively stacked magnetic layer (MnBi2Te4) and nonmagnetic layer (Bi2Te3). By means of scanning tunneling spectroscopy, we clearly observe the electronic state present at a step edge of a magnetic MnBi2Te4layer but absent at nonmagnetic Bi2Te3layers at 4.5 K. Furthermore, we find that as the temperature rises above TNthe edge state vanishes, while the point defect induced state persists upon an increase in temperature. These results confirm the observation of magnetism-induced edge states. Our analysis based on an axion insulator theory reveals that the nontrivial topological nature of the observed edge state.

Increased atmospheric nitrogen (N) deposition caused by human activities has potentially important effects on ecosystem carbon (C) dynamics and different effects on C fractions with different stabilities and chemical compositions. A better understanding of the responses of different C fractions to N addition is vital for maintaining soil quality and protecting vegetation. In order to investigate the differential effects of N addition on total soil organic carbon (SOC) and four SOC fractions with increasing degrees of oxidisability in Pinus tabuliformisrhizospheric and bulk soils, a 6-year pot experiment was performed testing the effects of the addition of N at rates of 2.8, 5.6, 11.2, 22.4 and 44.8g m–2year–1compared with a control (CK) group (no N addition). Addition of N addition had significant (P0.05) effects on SOC fractions of very labile C (C1) and recalcitrant C (C4), but negligible effects on total SOC (TOC) and SOC fractions of labile C (C2) and less labile C (C3). The C1 content and ratio of C1 to TOC in rhizospheres decreased following the addition of low levels (N2.8–N5.6) of N, but increased after the addition of high levels (N11.2–N44.8) of N, with minimum values obtained after the addition of 11.2N g m–2year–1. Low rates (N2.8–N5.6) of N addition considerably increased C4 and the ratio of C4 to TOC in the rhizosphere, whereas addition of high rates (N11.2–N44.8) of N decreased these parameters. The responses of C1 and C4 in the bulk soil to N addition were opposite. The SOC fraction was significantly higher in the rhizosphere than in the bulk soil, indicating large rhizospheric effects. However, increased N addition weakened these effects. These findings suggest that low rates (N2.8–N5.6) of N addition stabilise SOC against chemical and biological degradation, whereas increased rates of N addition increase the lability of SOC in the bulk soil. Thus, the rhizosphere plays a vital role in soil carbon stability and sequestration in response to N addition.