Ridge culture is a special conservation tillage method, but the long-term influence of this tillage system on soil aggregate-size stability in paddy fields is largely unknown in southwest of China. The paper is to eva...Ridge culture is a special conservation tillage method, but the long-term influence of this tillage system on soil aggregate-size stability in paddy fields is largely unknown in southwest of China. The paper is to evaluate soil aggregate stability and to determine the relationship between soil organic carbon (SOC) and soil aggregate stability. Soil samples at 0 cm-20 cm layer were adopted from a long-term (16 a) field experiment including conventional tillage: plain culture, summer rice crop and winter upland crop under drained conditions (PUR-r); and conservation tillage: ridge culture without tillage, summer rice and winter fallow with floodwater layer annually (NTR-f), winter upland crop under drained conditions (NTR-r), and wide ridge culture without tillage, summer rice crop and winter upland crop under conditions (NTRw-r), respectively. Different pretreatments, such as slaking in fast wetting, wetting and subsequent slaking, were applied to simulate the breakdown mechanisms of aggregates in paddy soil. The results show that soil particles contents were mainly consisted of silt (0.050 mm to 1.000 mm) in fraction of 42.9% to 51.2%, sand (0.050 mm to 0.001 mm) in fraction of 28.0% to 31.8%, and clay (<0.001 mm) in fraction of 17.9% to 25.4%. The amount of aggregate-size was greatly observed in fraction of 2.000 mm-6.720 mm under ridge culture in paddy soil (more than 50$) under slaking and wetting pretreatment. The proportion of soil macro-aggregates (>0.250 mm) in conservation tillage was greatly higher than that in conventional tillage under subsequent fast slaking treatment. Minimal differences of aggregate stability between slaking in fast wetting and wetting were observed, while significant differences were found between ridge culture and plain culture. The aggregate stability under slaking treatment ranked in the order of NTR-r>NTRw-r> NTR-f > PUR-r, while under wetting was NTRw-r > NTR-r > NTR-f >PUR-r. There was a positive correlation between the aggregate stability and SOC concentration under wetting, and a low correlation was observed under slaking pretreatment. Soil exposure with tillage and lack of rice/rape-seed stubble inputs caused declines in aggregation and organic carbon, both of which make soil susceptible to water erosion. Adoption of ridge culture with no-tillage integrated with crop rotation and stubble mulch significantly altered soil organic concentration. It was a valuable conservation practice for soil aggregation and soil organic carbon sequestration on paddy soil.展开更多
English globalization has actually triggered the localization of the English language, so Chinese-English is a fact not a hypothesis. This paper mainly discusses the origin of Chinese-English and tries to explore the ...English globalization has actually triggered the localization of the English language, so Chinese-English is a fact not a hypothesis. This paper mainly discusses the origin of Chinese-English and tries to explore the essential features of it through the theories of language migration and analysis of many examples. This paper points out, based on Standard English, Chinese-English is an English variety mainly used by the Chinese people. It is unavoidable, useful, and necessary to spread Chinese culture. Chinese-English and Chinglish are inter-language variants because Chinese cultural influences are different. Chinese-English has its own complete system, regularity, and stability. This paper further clarifies the position of the Chinese-English and treats the Chinese-English phenomenon dialecticly and scientifically.展开更多
The thermostability of three sulfur oxygenase reductases （SORs） was investigated from thermoacidophilic achaea Acidianus tengchongensis （SORAT） and Sulfolobus tokodaii （SORsT） as well as the moderately thermophi...The thermostability of three sulfur oxygenase reductases （SORs） was investigated from thermoacidophilic achaea Acidianus tengchongensis （SORAT） and Sulfolobus tokodaii （SORsT） as well as the moderately thermophilic bacterium Acidithiobacillus sp. SM-1 （SORsB）. The optimal temperatures for catalyzing sulfur oxidation were 80 ℃ （SORAT）, 85 ℃ （SORsT）, and 70 ℃ （SORsB）, respectively. The half-lives of the three SORs at their optimal catalytic conditions were 100 min （SORAT）, 58 min （SORsT）, and 37 min （SORsB）. In order to reveal the structural basis of the thermostability of these SORs, three-dimensional structural models of them were generated by homology modeling using the previously reported high-resolution X-ray structure of SORAA （from Acidianus ambivalens） as a template. The results suggest that thermostability was dependent on： （a） high number of the charged amino acid glutamic acid and the flexible amino acid proline, （b） low number of the therraolabile amino acid glutamine, （c） increased number of ion pairs, （d） decreased ratio of hydrophobie accessible solvent surface area （ASA） to charged ASA, and （e） increased volumes of the cavity. The number of cavities and the number of hydrogen bonds did not signifieantly affect the thermostability of SORs, whereas the cavity volumes increased as the thermal stability increased.展开更多
基金Funded by the Key Projects of National Science & Technology Pillar Program (No.2006BAD05B0-02) Sichuan Educational Committee for Youths (No.09ZB049)
文摘Ridge culture is a special conservation tillage method, but the long-term influence of this tillage system on soil aggregate-size stability in paddy fields is largely unknown in southwest of China. The paper is to evaluate soil aggregate stability and to determine the relationship between soil organic carbon (SOC) and soil aggregate stability. Soil samples at 0 cm-20 cm layer were adopted from a long-term (16 a) field experiment including conventional tillage: plain culture, summer rice crop and winter upland crop under drained conditions (PUR-r); and conservation tillage: ridge culture without tillage, summer rice and winter fallow with floodwater layer annually (NTR-f), winter upland crop under drained conditions (NTR-r), and wide ridge culture without tillage, summer rice crop and winter upland crop under conditions (NTRw-r), respectively. Different pretreatments, such as slaking in fast wetting, wetting and subsequent slaking, were applied to simulate the breakdown mechanisms of aggregates in paddy soil. The results show that soil particles contents were mainly consisted of silt (0.050 mm to 1.000 mm) in fraction of 42.9% to 51.2%, sand (0.050 mm to 0.001 mm) in fraction of 28.0% to 31.8%, and clay (<0.001 mm) in fraction of 17.9% to 25.4%. The amount of aggregate-size was greatly observed in fraction of 2.000 mm-6.720 mm under ridge culture in paddy soil (more than 50$) under slaking and wetting pretreatment. The proportion of soil macro-aggregates (>0.250 mm) in conservation tillage was greatly higher than that in conventional tillage under subsequent fast slaking treatment. Minimal differences of aggregate stability between slaking in fast wetting and wetting were observed, while significant differences were found between ridge culture and plain culture. The aggregate stability under slaking treatment ranked in the order of NTR-r>NTRw-r> NTR-f > PUR-r, while under wetting was NTRw-r > NTR-r > NTR-f >PUR-r. There was a positive correlation between the aggregate stability and SOC concentration under wetting, and a low correlation was observed under slaking pretreatment. Soil exposure with tillage and lack of rice/rape-seed stubble inputs caused declines in aggregation and organic carbon, both of which make soil susceptible to water erosion. Adoption of ridge culture with no-tillage integrated with crop rotation and stubble mulch significantly altered soil organic concentration. It was a valuable conservation practice for soil aggregation and soil organic carbon sequestration on paddy soil.
文摘English globalization has actually triggered the localization of the English language, so Chinese-English is a fact not a hypothesis. This paper mainly discusses the origin of Chinese-English and tries to explore the essential features of it through the theories of language migration and analysis of many examples. This paper points out, based on Standard English, Chinese-English is an English variety mainly used by the Chinese people. It is unavoidable, useful, and necessary to spread Chinese culture. Chinese-English and Chinglish are inter-language variants because Chinese cultural influences are different. Chinese-English has its own complete system, regularity, and stability. This paper further clarifies the position of the Chinese-English and treats the Chinese-English phenomenon dialecticly and scientifically.
基金Supported by the National Natural Science Foundation of China (31070042,30870039,30921065)partially by Open Funding Project of the National Key Laboratory of Biochemical Engineering,China (2010KF-2)
文摘The thermostability of three sulfur oxygenase reductases （SORs） was investigated from thermoacidophilic achaea Acidianus tengchongensis （SORAT） and Sulfolobus tokodaii （SORsT） as well as the moderately thermophilic bacterium Acidithiobacillus sp. SM-1 （SORsB）. The optimal temperatures for catalyzing sulfur oxidation were 80 ℃ （SORAT）, 85 ℃ （SORsT）, and 70 ℃ （SORsB）, respectively. The half-lives of the three SORs at their optimal catalytic conditions were 100 min （SORAT）, 58 min （SORsT）, and 37 min （SORsB）. In order to reveal the structural basis of the thermostability of these SORs, three-dimensional structural models of them were generated by homology modeling using the previously reported high-resolution X-ray structure of SORAA （from Acidianus ambivalens） as a template. The results suggest that thermostability was dependent on： （a） high number of the charged amino acid glutamic acid and the flexible amino acid proline, （b） low number of the therraolabile amino acid glutamine, （c） increased number of ion pairs, （d） decreased ratio of hydrophobie accessible solvent surface area （ASA） to charged ASA, and （e） increased volumes of the cavity. The number of cavities and the number of hydrogen bonds did not signifieantly affect the thermostability of SORs, whereas the cavity volumes increased as the thermal stability increased.
