The aim of the paper was to identify the changes in bilateral trade in agri-food products between the EU and China, as well as to assess – in mutual relations – ex post competitive advantages of major groups of agri-food products in 2008– 2015. The research is based on data from the Statistical Office of the European Union (Eurostat). The analysis covered the value, trade balance, shares in total trade and commodity structure of trade in agri-food products between the EU and China. Selected indices of revealed comparative advantage (XRCA, MRCA, RTA), Coverage Ratios (CR), Specialization Indicators (SI), and the indices of Intra-Industry Trade (IIT) were calculated for major product groups of the Combined Nomenclature. It was proved that bilateral trade in agri-food products between the EU and China has increased signifi cantly in 2008–2015, and the EU transformed from an importer to a net exporter. Despite the intensification of mutual trade, the importance of China in the EU export of agri-food products remained relatively small. The structure of bilateral trade in agri-food products between the EU and China is consistent with the distribution of comparative advantages obtained by exporters and it is shaped under assumptions of the theory of similarity of preferences, the theory of product differentiation of the Armington type, and the Heckscher-Ohlin-Samuelson theorem of resources abundance. It can be considered that the Chinese agri-food sector is still in the stage of a factor-driven economy, while the agriculture and food industry in the EU countries has reached the stage of an innovation-driven economy.
We investigated the responses of growth and non-structural carbohydrates to submergence and de-submergence in three wetland macrophyte species. Survival rate, recovery ability, and soluble sugar and starch contents of flood-tolerant Polygonum hydropiper and of flood-sensitive Phalaris arundinacea and Carex argyi from Dongting Lake wetlands were investigated after 20, 40, and 60 days of complete submergence without light and 10 days after de-submergence. Plant dry weight and soluble sugar and starch contents decreased in all species during the submergence period. The decreases were slowest in P. hydropiper, intermediate in C. argyi, and most rapid in P. arundinacea. After 60 days of submergence, survival rates were 100, 50, and 0 % in P. hydropiper, C. argyi, and P. arundinacea, respectively. After recovery, plant dry weight increased in P. hydropiper and in C. argyi, but decreased in P. arundinacea. Compared to pre-submergence, soluble sugar contents generally increased and then remained relatively constant after recovery in all species, while starch content increased in P. hydropiper and decreased in P. arundinacea with increasing submergence time. For C. argyi, starch content decreased after recovery from the 20-day submergence, but increased after recovery from the 40- and 60-day submergences. These data illustrate mechanisms behind the flood tolerance of P. hydropiper and the sensitivity to flooding in P. arundinacea and C. argyi. These mechanisms include lower consumption and quicker accumulation of non-structural carbohydrates in flood-tolerant plants.
Desertification is one of the most serious environmental problems on a global scale. China suffers from desertification over large areas. Landscape boundaries profoundly influence the structure and function of landscapes, and influence ecological processes both locally and over large scales. Data on soil properties and vegetation collected on three 110 km parallel transects across sandy land-steppe transition zone in Yanchi county, Ningxia region, northwestern China, were used to analyze changes along the sandy land/steppe boundary by using the Moving Split Window (MSW), to determine desertification dynamics, and to explore changes of vegetation and soil properties among different desertification degree. Combining the dissimilarity profiles of soil particle size with importance value (IV) of vegetation, four boundaries were detected along transects. According to the four boundaries, we divided the whole sandy land/steppe ecotone area into five desertification categories: potential desertification (PD), light desertification (LD), medium desertification (MD), severe desertification (SD) and extreme desertification (ED). Sand fractions increased, while silt and clay fractions, soil organic C, total N and available N decreased and exhibited clear gradient changes from the potential desertification land to the extreme desertification land. All areas we studied have been desertificated at different degree based upon soil particle compositions at different depths. With the aggravation of sandy desertification, the steppe species dominating in the potential desertification land gradually gave place to arid and sand tolerant perennials and therophytes and eventually to psammophyte annuals and shrubs in the extreme desertification land.
The paper determined the volume ratio of the main hull and side hull and their position characteristic parameter of operation and maintenance trimaran. Numerical simulation technology was used to do the analysis and calculation of trimarans which have different volume ratio of the main and side hull, and on this basis, the paper tried different positions of main and side hull, finally got the trimaran with optimum resistance performance and the chart of trimaran resistance estimation, so as to provide a new way in the selection of feature parameter of offshore wind farm maintenance trimaran and its resistance estimation
The Shiyang River Basin has been regarded as an important ecological protective area in the Hexi corridor in northwest China. Landsat TM, ETM+, and OLI images in 1986, 2000, 2006, and 2015 were selected as basic data resources, and the circle layers and fan-shaped analysis were applied to extract change information and the characteristics of land use pattern change by a set of transfer and dynamic models. Results showed that urban and residential land expanded 176.7 km², which was about 48.57% in the past 30 years, and that the woodland and grassland decreased 7.24% and 1.39%, respectively. It was found that woodland mainly distributed in the range of elevation from 2,500 to 4,000 m, and unused land was distributed in the downstream plain, which was an average elevation of 1,500 meters below. Moreover, the area and spatial distribution of land use were influenced by human activities and resulted in fundamental changes of pattern. We found that spatiotemporal pattern analysis of land use cover was essential for understanding the structure and characteristics of urbanization and the local eco-environment.
The study analysed the stability of polyphenols present in extracts isolated from cocoa, green tea and strawberries in Hank’s Balanced Salt Solution buffers. The extracts were incubated under conditions commonly used for intestinal absorption experiments with human epithelial cells. The polyphenols were analysed with HPLC-DAD-FLD-MS method. The concentrations of most of the polyphenols monitored changed during 2 h of incubation. The fl avan-3-ols of cocoa exhibited similar stability and all were more stable at pH 6.5 than 7.4. The concentration of procyanidin B2 at pH 7.4 decreased to the highest extent. Green tea predominant catechins: epigallocatechin gallate and epigallocatechin, were very vulnerable in HBSS both at pH 6.5 and 7.4; their specific molecular structure may be responsible for this phenomenon. The anthocyanins of a strawberry extract were more stable at pH 6.5. The considerable increase in ellagic acid concentration at pH 7.4 might be explained by possible degradation of other compounds of the extract. It is highly recommended to perform stability tests before transport experiments in a cell culture model in order to avoid misinterpretation of results.
An experiment was carried out to compare cadmium and copper absorption and mineral nutrition accumulation in pennisetum and tall fescue in order to select an appropriate grass to remediate Cd/Cu-contaminated soil and explore their detoxification mechanisms of contamination by mineral elements. The biomass remained constant in tall fescue under each Cd addition level and increased in pennisetum until Cu reached 500 μM, whereas they dramatically decreased as the Cu or Cd solution increased, which was concurrent with quadratic regression model analysis. The Cd/Cu concentrations in tall fescue were mostly accumulated in the roots and were much higher than those in pennisetum. The extracted amount of Cd in the shoots and the total Cu concentrations of pennisetum were higher than the corresponding values in tall fescue at every Cd/Cu addition level. Negative correlations were observed between Cd and shoot Ca, Cu, K, Mg, and Zn, and root Cu and Na of tall fescue and the root K of pennisetum. The Cu concentration was negatively correlated with K and positively correlated with Na in tall fescue and pennisetum under the Cu treatments. As the Cd/Cu concentration in solution increased, K/Na values were significantly decreased in the roots of tall fescue under Cu stress and pennisetum under Cd/Cu stress, whereas they increased in the roots of tall fescue under Cd addition. In summary, pennisetum exhibited the greater biomass and Cd/Cu extraction; indicating it as a candidate energy grass for phytoextraction. The adjustment capacity of grass for K and Na might relate to the tolerance to Cd/Cu.
To solve the dynamic response problems of magnetic coupling in the horizontal axis wave energy device, this has researched the dynamic characteristicsof magnetic coupling. The fitting formula about torque and angle of the magnetic coupling is obtained through experiments. The mathematical models of the magnetic coupling torque transmission are established. The steady state error of the magnetic coupling and the transfer function of the output angle are obtained. The analytical solution of the step response of the output angle in time domain is derived. The influence of the torsional rigidity, the damping coefficient and the driven rotor’s rotational inertia on dynamic characteristics of the magnetic coupling isanalyzed. According to the analysis results, the design rules of magnetic coupling are proposed
As energy crises and environmental pollution become increasingly prominent, people are beginning to explore the ocean to exploit its renewable energy. Based on hydrodynamic principles, an analytical model for unstable hydrofoil motion has been developed. The software ANSYS Fluent was employed to perform a simulation of hydrofoil motion, and the effect of hydrofoil motion on the surrounding flow field was analyzed. The hydrodynamic characteristics and energy-capturing efficiency of the hydrofoil were obtained, and the influence of complex flows on hydrofoil hydrodynamics was elucidated. The energy dissipation mechanism during hydrofoil motion was characterized. The results indicate that the vortex generation and shedding inevitably dissipates part of the tidal energy captured by the hydrofoil, which leads to abrupt changes in hydrofoil hydrodynamics and reduces energy-capturing efficiency. When the frequency of the abrupt hydrodynamics change matches the hydrofoil natural frequency, it may result in hydrofoil resonance and damage. Also, it is observed that larger pitch amplitude leads to larger optimalreduced frequency corresponding to the peak power cycle-averaged coefficient. The results also provide a theoretical guide on how to improve hydrofoil energy-capturing efficiency of the power generation system with control valves and extend hydrofoil life.
So far, azide has been consistently reported to act as an inhibitor of metal enzymes, especially copper proteins. The present work shows that azide can also act as an activator of polyphenol oxidase II (PPO II) from tobacco leaves. From the square-wave voltammetry of native PPO II, peroxide-PPO II complex and azide-PPO II complex, the reduction of nitro blue tetrazolium by the enzymes and activation of PPO II by peroxide it follows that the binding of azide to PPO II induces the formation of CuO2 2-Cu in the active site of PPO II from CuO2 -Cu in native PPO II. The reason for azide acting as an activator can be attributed to azide complexing with PPO II, thus inducing the formation of CuO2 2-Cu, which is the active site of the peroxide-PPO II complex in which peroxide plays the role of activator.
Hydrogen sulfide (H₂S) has the ability to strengthen plant stress tolerance; however, the effects of H₂S on wheat seedlings under salt stress and the underlying molecular mechanism are still unclear. This study examined the effects of exogenous NaHS as H₂S donor on photosynthesis, antioxidant system, and the expression profile of genes related to antioxidant defense responses, the salt overly sensitive (SOS) and mitogen-activated protein kinase (MAPK) pathways in wheat seedlings treated with NaCl stress. H₂S application improved photosynthesis, and decreased H₂O₂ and malondialdehyde (MDA) contents in wheat seedling leaves under NaCl stress. In addition, antioxidant enzyme activity and the content of ascorbic acid and reduced glutathione increased with H₂S application. Moreover, H₂S pretreatment up-regulated expression levels of genes related to antioxidant system, SOS pathway and MAPK pathway as well as the transcription factor dehydration-responsive element binding gene. Overall, these findings suggest that H₂S alleviates salt stress in wheat seedlings not only by strengthening antioxidant defense systems, but by coordinating signal transduction pathways related to the stress response at a transcriptional level.