Soil and Water Conservation and Integrated Management in Watershed Ecosystem of the Loess Plateau, China

The Loess Plateau is well known for severe soil erosion and ecosystem degradation. The key issues in this region are the food security (grain), ecological security and a sustainable economy. This paper reviews a range of studies on ecological restoration, and management and the benefit at watershed scale on the Loess Plateau. This includes several successful cases and failures in soil conservation. The paper presents practical soil conservation measures and related benefit analysis, and discusses some effective methods adopted in soil erosion control, research directions and future perspectives for the Loess Plateau

Large-scale soil organic carbon mapping based on multivariate modelling: The case of grasslands on the Loess Plateau

The Loess Plateau is considered one of the world's regions with severe soil erosion. Grasslands are widely distributed on the Loess Plateau, accounting for approximately 40% of the total area. Soil organic carbon (SOC) plays an important role in the terrestrial carbon cycle in this region. We compiled more than 1,000 measurements of plant biomass and SOC content derived from 223 field studies of grasslands on the Loess Plateau. Combined with meteorological factors (precipitation and air temperature) and the photosynthetically active radiation factor, the topsoil SOC contents of grasslands were predicted using the random forest (RF) regression algorithm. Predicted grassland SOC content (1.70-40.34gkg(-1)) decreased from the southeast to the northwest of the Loess Plateau, with approximately 1/5 of the grassland exhibiting values lower than 4gkg(-1). Observed SOC content was positively correlated with observed plant biomass, and for predicted values, this correlation was strong in the desert steppe and the steppe desert of rocky mountains. Air temperature was the most important factor affecting SOC contents in the RF model. Moreover, the residual error of observations and predictions increased as the grazing intensity varied from none to very severe in the temperate desert steppe, and this RF model may not perform well in plains. The use of the RF model for SOC prediction in Loess Plateau grasslands provides a reference for C storage studies in arid and semi-arid regions, and aboveground biomass and temperature should receive more attention due to increasing C sequestration

Estimates of carbon storage in grassland ecosystems on the Loess Plateau

Grassland ecosystems play an important role in the carbon (C) balance of arid and semi-arid regions. These ecosystems provide C for grass growth and soil microbial activities and represent one of the main sources of atmospheric C. In this study, we estimated the C density and storage of 223 sampling sites in grassland ecosystems on the Loess Plateau using elevation, vegetation indexes, precipitation, air temperature, day and night land surface temperature (LSTd and LSTn, respectively), evapotranspiration (ET), percent tree cover and the non-vegetated area to build decision regression tree and generalized linear regression models (GLMs). The results showed that the C density decreased from south to north and ranged from 0.22 to 29.29 kg C/m(2). The average amount of C stored in the ecosystems was 1.46 Pg. The typical steppe and forest steppe stored the most C, and the steppe desert stored the least. The soil (0-1 m) stored most of the organic C, accounting for > 90%, and the belowground biomass (BGB) contained > 3 times the amount of C as the aboveground biomass (AGB). This study provides reference information for the loss of C and associated mitigation strategies on the Loess Plateau

Application of Flower-Like ZnO Nanorods Gas Sensor Detecting Decomposition Products

Gas insulated switchgear (GIS) is an important electric power equipment in a substation, and its running state has a significant relationship with stability, security, and reliability of the whole electric power system. Detecting and analyzing the decomposition byproducts of sulfur hexafluoride gas (SF6) is an effective method for GIS state assessment and fault diagnosis. This paper proposes a novel gas sensor based on flower-like ZnO nanorods to detect typical SF6 decompositions. Flower-like ZnO nanoparticles were synthesized via a simple hydrothermal method and characterized by X-ray powder diffraction and field-emission scanning electron microscopy, respectively. The gas sensor was fabricated with a planar-type structure and applied to detect SF6 decomposition products. It shows excellent sensing properties to SO2, SOF2, and SO2F2 with rapid response and recovery time and long-term stability and repeatability. Moreover, the sensor shows a remarkable discrimination among SO2, SOF2, and SO2F2 with high linearity, which makes the prepared sensor a good candidate and a wide application prospect detecting SF6 decomposition products in the future

Interaction between physical activity and sleep duration in relation to insulin resistance among non-diabetic Chinese adults

It is of a public health interest to explore the relationship between different types of physical activity, sleep duration and diabetes/insulin resistance. However, little is known about such relationship. This study examines the single and joint associations of different types of physical activity, and sleep duration on insulin resistance among non-diabetic Chinese adults. Methods: Data was collected from 1124 non-diabetic adults in Jiangsu Province from the China Health and Nutrition Survey (CHNS). Domestic, occupational, transportation and leisure physical activity were assessed in terms of metabolic equivalent (MET)-hours-per-week to account for both intensity and time spent. Sleep duration was categorized into three groups: ≤ 7 hours, 7-9 hours, and ≥ 9 hours. Insulin resistance was evaluated by the homeostasis model of assessment (HOMA) and defined as the highest quartile of HOMA. Results: Total physical activity was mainly composed of occupational activity (75.1%), followed orderly by domestic, transportation and leisure time activity in both men and women. Total physical activity level was strongly negatively associated with fasting insulin and HOMA (p < 0.001). Among four types of physical activity, occupational activity was significantly negatively associated with HOMA after full adjustment (p < 0.05). Transportation activity was also negatively associated with HOMA when adjusted for age and gender (p = 0.028). Moreover, the combination of low physical activity and short sleep duration was associated with the highest odds of insulin resistance (adjusted OR = 3.26, 95% CI: 1.57-6.78), compared to those with high physical activity and adequate sleep duration. Conclusions: Physical activity, mainly occupational physical activity, was negatively associated with insulin resistance in non-diabetic Chinese population, independently of potential confounders. There was a synergic effect of low physical activity and short sleep duration on insulin resistance.Hui Zuo, Zumin Shi, Baojun Yuan, Yue Dai, Gang Hu, Gaolin Wu and Akhtar Hussai

Optimizing management to conserve plant diversity and soil carbon stock of semi-arid grasslands on the Loess Plateau

Grassland recovery from degradation is increasingly occurring worldwide. Diverse managements have been considered as effective ways to restore degraded grassland, but it remains unclear how semi-arid grasslands respond to long-term grazing exclusion and fenced mowing. Here, a study was conducted under open grazing, grazing exclusion and fenced mowing in a semi-arid grassland on the Loess Plateau. We measured plant species composition and diversity, plant production, surface litter and soil water and carbon content. Shifts in grassland management led to significant divergence in plant community composition. Long-term grazing exclusion (35 years) significantly increased plant biomass, surface litter, soil water and carbon storage, but suppressed plant diversity compared to open grazing. Conversely, fenced mowing significantly increased plant diversity accompanying with a weak effect on soil carbon. Moreover, mowing significantly reduced surface litter and soil moisture, which have strong implications for nutrient depletion and soil drying. Our results suggest that introducing disturbances are necessary to safeguard biodiversity, and continuous mowing (5 years) belongs to over exploitation of the long-term protected grassland. Therefore, it is essential to optimize management with dual objectives of biodiversity and soil carbon sequestration in the future

Association between serum keptin concentrations and insulin resistance: A population-based study from China

BACKGROUND Insulin resistance contributes to the cardio-metabolic risk. The effect of leptin in obese and overweight population on insulin resistance was seldom reported. METHODS A total of 1234 subjects (572 men and 662 women) aged ≥18 y was sampled by the procedure. Adiposity measures included BMI, waist circumference, hip circumference, WHR, upper arm circumference, triceps skinfold and body fat percentage. Serum leptin concentrations were measured by an ELISA method. The homeostasis model (HOMA-IR) was applied to estimate insulin resistance. RESULTS In men, BMI was the variable which was most strongly correlated with leptin, whereas triceps skinfold was most sensitive for women. More importantly, serum leptin levels among insulin resistant subjects were almost double compared to the subjects who had normal insulin sensitivity at the same level of adiposity in both men and women, after controlling for potential confounders. In addition, HOMA-IR increased significantly across leptin quintiles after adjustment for age, BMI, total energy intake, physical activity and smoking status in both men and women (p for trend <0.0001). CONCLUSIONS There was a significant association between HOMA-IR and serum leptin concentrations in Chinese men and women, independently of adiposity levels. This may suggest that serum leptin concentration is an important predictor of insulin resistance and other metabolic risks irrespective of obesity levels. Furthermore, leptin levels may be used to identify the cardio-metabolic risk in obese and overweight population.Hui Zuo, Zumin Shi, Baojun Yuan, Yue Dai, Gaolin Wu, Akhtar Hussai

Fault location in the outer sheath of power cables

With the development of power systems in recent years, the total amount of power cables in operation has increased greatly, and there are growing reports of cable failure. Cable failures may be due to various intrinsic or extrinsic factors and can lead to massive economic loss. With regard to high-voltage cables, such as 110 kV power cables, there are very few accurate reports on the actual fault observed. This article first analyses the possible causes of power cable outer sheath failure. It then introduces the bridge and step voltage methods, which are traditionally used for cable fault locating, and describes a new method for accurate fault locating in 110 kV cables, which uses the bridge method to pre-locate the fault and then the step voltage method to accurately determine the precise fault locating. Field testing confirms the applicability of the new method for accurate fault locating in 110 kV power cables. The results shown in this article may provide a good reference for the development of future research in related field

Synthesis, Characteristics and Enhanced Sulfur Dioxide Sensing Properties of Cu-doped SnO2 Microspheres

Abstract: Sulfur dioxide (SO2) is a typical sulfur hexafluoride (SF6) decomposition by product in gas insulated switchgear (GIS). Online monitoring and analyzing SO2 gas concentration can timely and effectively evaluate the insulation performance of SF6-gas-insulated apparatus. In this study, pure and 3 at % Cu-doped SnO2 microspheres were synthesized via a simple and facile hydrothermal method, and were characterized by X-ray powder diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, respectively. Chemical gas sensors were fabricated with the conventional indirect heating technology and their gas sensing properties versus SO2 were investigated in detail. The gas sensor fabricated with 3 at % Cu-doped SnO2 microspheres exhibits lower optimum operating temperature and higher gas response than that of pure SnO2 microspheres. Meanwhile, it demonstrates good stability and fast response-recovery. Most importantly, this sensor holds excellent discrimination with other SF6 decompositions, including SOF4, SOF2, SO2F2 and HF. All results provide a good candidate in fabricating high-performance SO2 sensor in practice. Copyright © 2013 IFSA

Cellulosic particles accumulation phenomenon and its effect on the electric field distribution in natural ester and mineral oil under AC electric field

Natural esters usually show higher dielectric losses, a higher conductivity and higher viscosity. It has become clear that more research is required to ascertain the long-term safe operation of transformers where natural ester is used. This paper made comparative experimental analysis of the cellulosic particles accumulation and its effect on the electric field distribution in natural ester and mineral oil under AC electric field. When the AC voltage was applied on the oil with cellulose particles, it is worth noting that in mineral oil, the particles were concentrated at the end of the spherical positive and negative electrodes, while in the natural ester, the particles are concentrated in the sphere of the positive and negative electrodes. The adsorption of fiber particles decreases the field intensity near the spherical electrode, however, increases the field strength in the middle region of the electrode. Besides, in the case of particles adsorbed on the electrode surface, the maximum electric field strength appears at the particle edge in mineral oil is a little higher than the value in natural ester