Based on the autoregressive distributed lag (ARDL) bounds testing approach and vector error correction model (VECM) Granger causality approach, this paper explores the relationships among per capita ...carbon dioxide (CO2) emissions, gross domestic product (GDP), renewable, non-renewable energy production and foreign trade for China covering the period 1980–2014. One finding is that there is a long-run relationship among those variables. Another important finding is that China does not have the Environmental Kuznets Curve (EKC) of CO2 emissions under the influence of economic growth, non-renewable energy production and foreign trade. However, after the addition of renewable energy production variable, it is found that the inverted U-shaped EKC hypothesis is supported in the long-run. Our long-run estimates show that increasing non-renewable energy and GDP increases CO2 emission, whereas renewable energy and foreign trade have a negatively impact on CO2 emissions. The short-run Granger causality tests show that there are bidirectional causalities running from foreign trade, CO2 emission and non-renewable energy to renewable energy. Furthermore, the finding indicates that renewable energy consumption is a key solution in reducing CO2 emissions over time. Finally on the basis of this study, we put forward the corresponding countermeasures and suggestions on China's carbon emission reduction strategy.
•Examine the relationships among CO2 emissions, renewable energy and trade.•It is found that the inverted U-shaped EKC hypothesis is supported.•Renewable energy and trade have a negative impact on CO2 emissions in the long-run.•There is bidirectional causality running from CO2 emission to renewable energy.
The soil–water retention curves (SWRC) of soil plays a key role in unsaturated soil mechanics, which is a relatively new field of study having wide applications particularly in geotechnical and ...geo-environmental engineering. SWRCs were used to evaluate the ability of unsaturated soils to attract water with various water contents and matric suctions. Drying and wetting SWRCs for a sandy soil with different dry densities were studied in a laboratory. Proton nuclear magnetic resonance, image processing technology, and mercury intrusion porosimetry were used to characterize the microscopic mechanisms of pore size distribution in the soil. Soil–water retention in the soil samples was strongly dependent on the dry density. With zero matric suction, soil samples with a higher dry density had a lower initial volumetric water content. Volumetric water content changed at a slower rate when values of matric suction increased in soils with a higher dry density. Soil samples had residual matric suction and a larger air-entry value with a smaller slope of the SWRC when they had a higher density. Dry density change is mainly responsible for the large pores. The number of large pores decreased as dry density increased. As the dry density increased, the area of macropores occupying the largest portion decreased, while the area of mesopores and micropores increased. Minipores accounted for the smallest proportion of total area and they were nearly constant. The proportion of large diameter pores decreased relative to pores with small diameters in the tested soils. The total pore volume was lower for soil specimens that had larger dry densities, as compared to relatively loose specimens. There was hysteresis between the drying and wetting curves for all soil samples. Hysteresis decreased as the dry density of the soil increased. The different liquid–solid contact angle was the main factor causing hysteresis of SWRC.
Most of traditional Chinese medicine substances come from herbal plants. The medicinal quality of herbal plants varies with the locations of cultivation, the parts of the herb collected, the season ...of the herb collected, and the herb processing method. Polysaccharides are major components of the herb plants and their biosynthesis is partly controlled by the genes but mostly influenced by the availability of the nutrition and determined by the various environmental factors. In recent decades, polysaccharides isolated from different kinds of Chinese herbs have received much attention due to their important biological activities, such as anti-tumor, anti-oxidant, anti-diabetic, radiation protecting, antiviral, hypolipidemic, and immunomodulatory activities. Interestingly, different batches of the same herb can obtain different polysaccharide fractions with subtle differences in molecular weight, monosaccharide compositions, glycosidic linkages, and biological functions. Even with these variations, a large number of bioactive polysaccharides from different kinds of traditional Chinese herbs have been purified, characterized, and reported. This review provides a comprehensive summary of the latest polysaccharide extraction methods and the strategies used for monosaccharide compositional analysis plus polysaccharide structural characterization. Most importantly, the reported chemical characteristics and biological activities of the polysaccharides from the famous traditional Chinese herbs including Astragalus membranaceus, Ginseng, Lycium barbarum, Angelica sinensis, Cordyceps sinensis, and Ophiopogon japonicus will be reviewed and discussed. The published studies provide evidence that polysaccharides from traditional Chinese herbs play an important role in their medical applications, which forms the basis for future research, development, and application of these polysaccharides as functional foods and therapeutics in modern medicine.
Calcareous sand containing weak particles originated from the deposition of skeletal residue of marine organisms is susceptible to significant particle crushing under compression and shearing. The ...breakage of grains results in excessive deformation and foundation failure. This study focuses on the mechanical properties and particle crushing of calcareous sand retrieved from Nansha Island, South China Sea. A series of isotropically drained and undrained triaxial compression tests were performed on reconstituted calcareous sand samples at different initial densities and at a wide range of confining stresses. The amount of particle crushing for calcareous sand after shearing was measured and quantified. Experimental results demonstrate that the shear response of calcareous sand had been well interpreted within the critical state framework. The amount of particle crushing for calcareous sand increases with increasing density and confining stress. Compared with the undrained condition, a larger amount of particle crushing of calcareous sands is observed in the drained triaxial compression test. Stress-dilatancy curves exhibit similar varying tendency for calcareous sand. Multiple critical state lines for calcareous sands with different initial densities are identified in the void ratio and logarithm of the mean stress plane. Considering the variation in stress ratio at the critical state induced by particle crushing, all stress paths are normalized to determine the state bounding surface for calcareous sand at varying densities and stresses.
•Particle crushing for calcareous sand is jointly governed by density, stress level, and drainage condition.•Particle crushing-induced position shift of critical state line is observed for calcareous sand.•Bounding state surface is identified for calcareous sand at various initial densities.
Life skills (LS) training programs help individuals develop their mental health and stress-related attitudes. This study aims to build a versatile physical education program (PEP) to promote LS and ...examine its effectiveness. The subjects were first-year Japanese university students. We conducted the LS survey in April (pre-semester) and August (post-semester) 2019. To analyze the difference in LS subscales scores depending on the PEP at the pre-semester/post-semester, we conducted two-way ANOVA repeated measures with the Semester-Sports item and examined simple main effects. As a result, there were significant interactions on the subscales "leadership (F (2,285) = 8.20, P < 0.001), " "planning (F (2,285) = 3.97, p < 0.05)," "self-esteem (F (2,285) = 7.73, p < 0.001)," and "positive thinking (F (2,285) = 3.07, p < 0.05)." Multiple comparison results showed that average scores for Tai Chi were significantly higher than Nordic walking and Basketball at the pre-semester. Moreover, there was a significant difference in all LS subscales between pre-semester and post-semester. This study suggested this PEP effectively developed the LS for new university students.
This study explored the effects of economic growth (EG), renewable energy consumption (REC) and non-renewable energy consumption (NREC) on CO2 emissions (CE) and tested the Environmental Kuznets ...Curve (EKC) hypothesis at the regional levels in China. The study was based on a balanced provincial panel dataset for the period of 1995–2012. The empirical results suggested that the inverted U-shaped EKC hypothesis was not supported in the central and western regions and was barely supported in the eastern region. NREC was found to have a positive effect on CE, although this varied across the three regions, with the greatest impact being in the central region, followed by the western and eastern regions. REC had a negative impact on CE in the eastern and western regions, while the impact was weak and statistically insignificant in the central region. Furthermore, we found that REC had no significant impact on the EKC hypothesis in the three regions. Panel causality tests showed that the direction of causality in both short and long runs was mixed among regions. There were bidirectional causalities between REC, CE, and EG in the long-term for the three regions.
•Examine the relationships among CO2 emissions, economic growth, renewable and non-renewable energy.•The inverted U-shaped EKC hypothesis isn’t supported in the central and western regions.•The impact of renewable energy on the CO2 emissions varies across regions.•There are bidirectional causalities between renewable energy, CO2 emissions and economic growth in the three regions.
Scientific location selection of schools is an important way to optimize the allocation of educational resources, improve the efficiency of operating schools, and realize the balanced development of ...education, especially in rural areas. Many studies have considered the location of schools, but most have omitted the impact of transportation network conditions and the time cost differences caused by different travel speeds under different road conditions. The object of this study is to minimize the total transportation costs for students, construction costs for new schools, and the construction and upgrading costs for roads on a traffic network with travel time uncertainty indicated by different travel time scenarios. A mixed-integer programming model for this problem was proposed. Furthermore, a hybrid simulated annealing algorithm was used to solve the problem. Finally, a practical case study was used to illustrate the application of the proposed mathematical model. The results showed that the traffic network has an important influence on the optimization location of rural schools, and the improvement of traffic network conditions can greatly reduce the time required for students to travel to school.
Groundwater inrush from aquifers underlying coal seams is a serious geohazard during coal mining in China. Its occurrence is affected by multiple factors, while the importance of these factors may ...change over the entire mining area. Traditional model with constant weight cannot reflect the influence of index value mutates with changes in hydrogeological conditions on the comprehensive evaluation value. The theory of variable weight model is thus proposed to evaluate the dynamic processes involved in groundwater inrushes. The model is applied to the Yuzhou coalfield in north China to demonstrate the construction process of the variable weight model and to verify its improvement over the traditional constant weight model in assessing the vulnerability of groundwater inrushes from the underlying aquifers. This innovative method offers not only another tool on assessment of groundwater bursting but also has practical significance in reducing water geohazards in mines.
In light of the disastrous the 2011 Tohoku Pacific Earthquake, the government of Japan has conducted studies to revise the seismic design code, and elevated peak ground accelerations have been ...adopted. Consequently, revisions on existing design to comply with the updated code are required for public projects that are still undergoing. The design safety needs to be reassessed, and implementation of strengthening measures is required if deemed necessary. For liquefaction countermeasures, ground treatment techniques that could increase the density of soils are often the preferable alternatives. The treatment usually increases the in situ SPT-N or CPT-q
c
values, which in turn would increase the resistance of soil against liquefaction. For many public infrastructures in Japan supported by bored piles embedded partly or entirely in sandy soils, reevaluation of design safety against soil liquefaction would be required. In an assessment of possible retrofitting countermeasures for an infrastructure foundation, ground treatment has been considered. In this case study, effect of ground treatment on response of piles in liquefiable soils was investigated with numerical analyses using FLAC. Results provide insights into this ground treatment effect and useful information for consideration in future design or decision making.
•A simple and accurate HPLC method was developed for simultaneously determination six flavonoids.•Bioactive flavonoids and antioxidant activity in PCR ‘Chachi’ during three years were ...evaluated.•Polymethoxylated flavones could be used as indexes for the quality change of ‘Chachi’ PCR during storage.
A simple and accurate method using high performance liquid chromatography (HPLC) with dual wavelength detection was developed to simultaneously determine the contents of one flavanone glycoside (hesperidin) and five polymethoxylated flavones (PMFs: sinensetin, 4′,5,7,8-tetramethoxyflavone, nobiletin, tangeretin and 5-O-desmethyl nobiletin) in Pericarpium Citri Reticulatae (Citrus reticulata ‘Chachi’) (‘Chachi’ PCR). By modifying the mobile phase compositions and detection wavelengths, an optimal HPLC condition was obtained, under which the calibration curves of all six compounds exhibited good linearity (R2>0.99). For all the tested compounds, the relative standard deviation (RSD) was less than 4%, and the accuracy ranged from 97.58 to 103.2%. The developed method was successfully applied to monitor the changes in the contents of six flavonoids in ‘Chachi’ PCR during storage at 25°C, over a three year period. Color parameters and antioxidant capacity were also determined to evaluate the sample quality. The contents of hesperidin decreased while all the polymethoxylated flavones and antioxidant activities increased throughout the storage period, demonstrating that polymethoxylated flavones could be used as indices for the quality change of Chachi’ PCR during storage. The results from this study suggest that the longer storage periods increased the quality of PCR.
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