Science China Press., Co. Ltd.

Grafting is widely used for various aspects of plant biological research. We reviewed grafting methods and graft development processes for herbaceous plants. We introduced also methods of investigating the development of graft union and compatibility, and the application of grafting in understanding translocation of substances and long-distance signaling in plants.

Interdigestive gastrointestinal migrating motor complex (MMC) activities were recorded by strain gauge implanted on the serosa in 7 conscious dogs. We studied the effects of electroacupuncture (EAP) Weijing points Zusanli (S36), Tianshu (S25), Liangmen (S21) on MMC and release of motilin and gastrin, and compared them with that of EAP Pangguangjing points. The results indicated that EAP Weijing points could not only strengthen MMC contractions in antrum, duodenum and proximal jejunum, but also increase plasma concentration of motilin and gastrin. Anti-motilin serum, proglumide, atropine, or hexamethonium could markedly block the effect of EAP on reinforcing MMC contraction and release of motilin and gastrin. We could get the conclusions that such enhancing effect of EAP Weijing points on MMC and brain-gut peptides release is mediated by motilin and gastrin, on which both cholinergic nerve and sympathetic nerve play important roles.

In a sediment sequence from Erlongwan maar lake that spans the last 13 ka BP, two main varve types can be recognized: biogenic varves (from the present to ∼11.2 ka BP, 0–632 cm) and clastic varves (from ∼11.2 to ∼12.7 ka BP, 632–700 cm). Based on the dominant types of algae contained in the sediment, the biogenic varves can be classified into dinocyst-biogenic varves (0–63 cm) and mixed (dinocyst and diatom)-biogenic varves (214–632 cm). In this paper, the formation process and components of the varve are described, the possible reason for the types of varve changing throughout the record is discussed and a high-resolution varve chronology is established spanning the last 13 ka BP. Although further varve counting and error assessment are needed, the results presented here represent a solid foundation for studying the palaeoclimate record of Erlongwan maar lake.

The catalytic activities of seven immature source rocks in China on fatty acid decarboxylation for generating hydrocarbons have been evaluated by determinating the CO2 content from decarboxylation reaction of stearic acid. It has been found that the catalytic activities of immature source rocks mainly depend on the structure type of the minerals. In general, the catalytic activities of carbonates are higher than those of clays at low temperature. The higher its iron content, the higher the catalytic activity of carbonate.

A hybrid spectrum sensing and geolocation database framework is proposed to tackle the discovery of spatial-temporal spectrum hole in cognitive radio networks. We first analyze the advantages and disadvantages of spectrum sensing-based and geolocation database-based approaches respectively, which motivate us to further propose a hybrid protocol framework by effectively integrating the benefits of both spectrum sensing and geolocation database. Specifically, in the proposed hybrid approach, the goal is to maximize the utilization of spatial-temporal spectrum hole while satisfying the protection constraints for the primary users. Analytical and numerical results demonstrate the superior performance of the proposed hybrid approach over the existing spectrum sensing only and geolocation database only approaches, in terms of interference-free throughput. This article serves as a fundamental framework for advancing the design of hybrid approaches for spatial-temporal spectrum hole discovery.

This paper studies interdecadal variations of heat waves and sultry weather (HW&SW) in Beijing City by using climatological data gathered from 1940–2000. In general, HW&SW decreased during the 1940s–1970s and increased during the 1970s–1990s. Although variation trends in the number of HW&SW days coincide with air temperature variations, the greatest number of HW&SW days occurred during the 1940s rather than during the much hotter 1990s (which had an average 1.0°C higher air temperature than during the 1940s). The synoptic situations of HW&SW and the correlation analysis between HW&SW occurrences and the Western Pacific Subtropical High (WPSH) index seem to indicate that HW&SW days during the 1990s should exceed those during the 1940s; however, that is not the case. Post-1980s interdecadal variations of the Urban Dry Island (UDI) effect in Beijing City were analyzed in order to explain this inconsistent phenomenon. Our results show that, while the probability of HW&SW occurrences in Beijing City should have been greater due to global warming and increasing summer Urban Heat Island (UHI) intensity, the UDI effect is magnified by rapid urbanization. In addition, the physical comfort index is more sensitive to relative humidity under high temperature conditions. Therefore, the occurrence of HW&SW days during the 1990s is partially offset by the enhanced UDI in Beijing City.

The secondary biogenic coalbed gas, a new genetic and energy source type of coalbed gas in China, has been found in Xinji, Liyazhuang and Enhong areas. The essential characteristics of this type of gas are: (i) the major component of the gas is methane, with C1/C1–5 value higher than 0.99, indicating that the gas is part of dry gas; (ii) the δ13C1 value is in the range of −61.7‰ to −47.9‰, mostly lower than −55‰, which is much lower than the estimated δ13C1 value of thermogenic methane according to the thermal evolution degree of the coal rocks (with Ro value from 0.87% to 1.43%), showing the characteristics of the secondary biogenic gas; (iii) the δD value of methane ranges from −244‰ to −196‰; (iv) δ13C2 value ranges from −26.7‰ to −15.9‰ and δ13C3 value ranges from −10.8‰ to −25.3‰, indicating that the heavier hydrocarbons have a thermogenic origin; (v) the content of CO2 is very low, and δ13CCO2 value changes greatly, reflecting a characteristic of secondary change; (vi) δ15N2 value ranges mainly from −1‰ to + 1‰, indicating N2 derived significantly from air. The negative linear correlation between the contents of N2 and CH4 reflects the activity of bacteria bearing surface water infiltrating into coal beds. The comprehensive tracing indices show that the coalbed gas in the studied areas is the mixed gas of primarily secondary biogenic gas and a part of remnant thermogenic gas. The uplift of coal beds and the development of faults in the studied areas create favorable conditions for the formation of the secondary biogenic gas.