The oat panicle components were changed by the forms of nitrogen use influencing productivity. The aim of the study was to determine the direct and indirect effects of oat panicle components on grain yield by N-fertil...The oat panicle components were changed by the forms of nitrogen use influencing productivity. The aim of the study was to determine the direct and indirect effects of oat panicle components on grain yield by N-fertilizer rates in succession systems of high and reduced release of N-residual. The study was conducted in the years 2013 and 2014 in a randomized complete block with four replications in a factorial 3 × 2, for nitrogen rates (30, 60 and 120 kg·ha<sup>-1</sup>) and oat cultivars (Barbarasul and Brisasul) the soybean/oat and corn/oat systems. The panicle weight and grain per panicle show greater sensitivity to the change of nitrogen rates. Grain yield was favored by the direct effect of harvest index panicle and indirect by grain weight per panicle. In the system soybean/ oat, the grain weight of panicle shows greater efficiency in promoting positive direct effects on grain yield.展开更多
Expression of insecticidal protein for transgenic Bacillus thuringiensis （Bt） cotton is unstable and related to nitrogen metabolism. The objective of this study was to investigate the relationship between leaf carbo...Expression of insecticidal protein for transgenic Bacillus thuringiensis （Bt） cotton is unstable and related to nitrogen metabolism. The objective of this study was to investigate the relationship between leaf carbon nitrogen ratio （C/N） and insecticidal efficacy of two Bt cotton cultivars. C/N ratio and Bt protein content were both measured at peak square period and peak boll period respectively under 5-7 d high temperature and different nitrogen fertilizer rates on the Yangzhou University Farm and the Ludong Cotton Farm, China. All plants were grown in field. The results showed that the C/N ratio enhanced slightly and the Bt protein content remained stable at peak square period, but significant increases for the C/N ratio and decreases markedly for the leaf Bt protein concentration were detected at the peak boll period. The similar patterns at the two growth periods were found for the leaf C/N ratio and Bt protein content by different N fertilizer treatments. When nitrogen rate was from 0 to 600 kg ha-l, the C/N ratio was reduced by 0.017 and 0.006 for Sikang 1 and Sikang 3 at peak square period, compared to the 1.350 to 1.143 reduction for Sikang 1 and Sikang 3 at peak boll period, respectively. Correspondingly, the leaf Bt protein contents were bolstered by 2.6-11.8 and 26.9-36.9% at the two different growth periods, respectively. The results suggested that enhanced C/N ratio by high temperature and nitrogen application may result in the reduction of inseetiocidal efficacy in Bt cotton, especially in peak boll period.展开更多
There are abundant Bajocian—Tithonian bivalves in the main ridge of the Tanggula Mountains of northern Qinghai—Xizang Plateau, China. After figuring the common and coeval species between Tanggula and other areas (Fi...There are abundant Bajocian—Tithonian bivalves in the main ridge of the Tanggula Mountains of northern Qinghai—Xizang Plateau, China. After figuring the common and coeval species between Tanggula and other areas (Fig. 1), and tracing the temporal and spacial historical distribution of the bivalves very capable of dispersion, some Jurassic bivalve biogeographic items, particularly the biogeographic relations, have been lit up. In the known 21 taxa of the Jurassic Pectinoida and Ostreoida from the main ridge of the Tanggula Mountains, there are 12 (57%) common and coeval species in northern Tethys, 13 (62%) common and coeval species in southern Tethys and 12 (57%) in Kachchh—southern Xizang area. It has demonstrated that there existed intermigration of bivalves between Tanggula and various parts of Tethys. Although there is no coeval species between Tanggula and western Australia, in these two areas there exist 6 (29%) close range common species of which 4 (19%) coevaity existed in western Australia and India Plate. Tanggula fauna is, therefore, still very close to that of western Australia. However, there are 15 (71%) common and 14 (67%) coevality species between the main ridge of the Tanggula Mountains and northwestern Europe, among the common species, 8 (38%) ones have lower limitation (first occurrence) in northwestern Europe but only 2 (10%) taxa are older in the main ridge of the Tanggula Mountains. It is very clear that pectinite and ostrea fauna of Tethys, particularly the main ridge of the Tanggula Mountains and Europe had very close relation and most Tanggula’s or northern Tethyan taxa migrated from northwestern Europe.展开更多
In nutrient-limited alpine meadows,nitrogen(N) mineralization is prior to soil microbial immobilization;therefore,increased mineral N supply would be most likely immobilized by soil microbes due to nutrient shortage i...In nutrient-limited alpine meadows,nitrogen(N) mineralization is prior to soil microbial immobilization;therefore,increased mineral N supply would be most likely immobilized by soil microbes due to nutrient shortage in alpine soils.In addition,low temperature in alpine meadows might be one of the primary factors limiting soil organic matter decomposition and thus N mineralization.A laboratory incubation experiment was performed using an alpine meadow soil from the Tibetan Plateau.Two levels of NH4NO3(N) or glucose(C) were added,with a blank without addition of C or N as the control,before incubation at 5,15,or 25 ℃ for 28 d.CO2 efflux was measured during the 28-d incubation,and the mineral N was measured at the beginning and end of the incubation,in order to test two hypotheses:1) net N mineralization is negatively correlated with CO2 efflux for the control and 2) the external labile N or C supply will shift the negative correlation to positive.The results showed a negative correlation between CO2 efflux and net N immobilization in the control.External inorganic N supply did not change the negative correlation.The external labile C supply shifted the linear correlation from negative to positive under the low C addition level.However,under the high C level,no correlation was found.These suggested that the correlation of CO2 efflux to net N mineralization strongly depend on soil labile C and C:N ratio regardless of temperatures.Further research should focus on the effects of the types and the amount of litter components on interactions of C and N during soil organic matter decomposition.展开更多
Salinization in estuarine wetlands significantly alters the balance between their nitrogen(N)removal and retention abilities but these processes have not yet been characterized effectively.In the present study,the pot...Salinization in estuarine wetlands significantly alters the balance between their nitrogen(N)removal and retention abilities but these processes have not yet been characterized effectively.In the present study,the potential rates of sediment denitrification,anaerobic ammonium oxidation(anammox),and dissimilatory nitrate reduction to ammonium(DNRA)were mapped using N isotope tracing methods along salinity gradients across the Yellow River Delta wetland(YRDW)in China.The contribution of anammox to total dissimilatory N transformations in YRDW was merely 6.8%,whereas denitrification and DNRA contributed 52.3%and 40.9%,respectively.The potential rate of denitrification(5.82μmol/kg/h)decreased significantly along salinity gradients and markedly exceeded DNRA potential rate(2.7μmol/kg/h)in fresh wetlands,but was lower than that of DNRA in oligohaline wetlands(3.06 and 3.18μmol/kg/h,respectively).Moreover,a significantly positive relationship between salinity and DNRA/denitrification was obeserved,indicating that increased salinity may favor DNRA over denitrification.Furthermore,total sulfur(TS)content and ratio of total organic carbon to total nitrogen(C/N)increased with the salinity gradient and showed evident positive relationships with the DNRA/denitrification ratio.In this study,we proved that increased salinization resulted in the dominance of DNRA over denitrification,possible through the addition of S and alteration of the C/N in estuarine wetlands,leading to increased N retention in estuarine wetlands during salinization,which would enhance the eutrophication potential within wetlands and in downstream ecosystems.展开更多
Rapid nitrogen(N) transformations and losses occur in the rice rhizosphere through root uptake and microbial activities. However,the relationships between rice roots and rhizosphere microbes for N utilization are stil...Rapid nitrogen(N) transformations and losses occur in the rice rhizosphere through root uptake and microbial activities. However,the relationships between rice roots and rhizosphere microbes for N utilization are still unclear. We analyzed different N forms(NH+4,NO-3, and dissolved organic N), microbial biomass N and C, dissolved organic C, CH4 and N2O emissions, and abundance of microbial functional genes in both rhizosphere and bulk soils after 37-d rice growth in a greenhouse pot experiment. Results showed that the dissolved organic C was significantly higher in the rhizosphere soil than in the non-rhizosphere bulk soil, but microbial biomass C showed no significant difference. The concentrations of NH+4, dissolved organic N, and microbial biomass N in the rhizosphere soil were significantly lower than those of the bulk soil, whereas NO-3in the rhizosphere soil was comparable to that in the bulk soil. The CH4 and N2O fluxes from the rhizosphere soil were much higher than those from the bulk soil. Real-time polymerase chain reaction analysis showed that the abundance of seven selected genes, bacterial and archaeal 16 S rRNA genes, amoA genes of ammonia-oxidizing archaea and ammonia-oxidizing bacteria, nosZ gene, mcrA gene, and pmoA gene, was lower in the rhizosphere soil than in the bulk soil, which is contrary to the results of previous studies. The lower concentration of N in the rhizosphere soil indicated that the competition for N in the rhizosphere soil was very strong, thus having a negative effect on the numbers of microbes. We concluded that when N was limiting, the growth of rhizosphere microorganisms depended on their competitive abilities with rice roots for N.展开更多
Nine enclosures (5 m x 5 m) were built in a Fenneropenaeus chinensis culture pond of Rushan Gulf in April, 2001. The probiotics and BIO ENERGIZER solution were applied for disparate treatments. Variations of alkaline ...Nine enclosures (5 m x 5 m) were built in a Fenneropenaeus chinensis culture pond of Rushan Gulf in April, 2001. The probiotics and BIO ENERGIZER solution were applied for disparate treatments. Variations of alkaline phosphatase ac- tivity (APA) and its relationship with the contents of C, N and P in sediments were studied. Results show that APA of sedi- ments increases from 3.096 nmolg-1min-1 to 5.407 nmol g-1min-1 in culture period; the bacteria biomass is not the only factor to determine APA; the contents of total P and total organic carbon have a significant positive correlation with APA, while that of total nitrogen has a negative correlation. In addition, the contents of inorganic P and organic P are not regular with APA. By comparison, TOC shows a more significant coherence with APA, meaning that organic pollution in sediments af- fects APA remarkably.展开更多
Native orchid species of Singapore in their natural conditions experience stress from high irradiance, high temperatures and periods of extended low rainfall, which impact orchid plant physiology and lead to reduced g...Native orchid species of Singapore in their natural conditions experience stress from high irradiance, high temperatures and periods of extended low rainfall, which impact orchid plant physiology and lead to reduced growth and productivity. In this study, it was found that there was a reduction in photochemical efficiency of photosystem II (PSII) in 6 native orchid species under high light (HL) and Bulbophyllum membranaceum under low light (LL). There was chronic photoinhibition in these 6 orchid species over a period of 3 months after transplanting onto the tree trunks without watering and fertilization, especially in Coelogynes mayeriana and Bulbophyllum membranaceum under both HL and LL. This chronic photoinhibition caused by sustained period of water deficit in their natural conditions was later reversed by natural re-watering conditions from higher rainfall. These results indicate that water deficit has a greater impact on photosynthetic light utilization efficiency than excess light. The present study also showed that after natural rewatering, relative water content (RWC) of leaves and pseudobulbs generally increased. During the natural re-watering, total leaf area also gradually increased and reached maximum expansion after 7 weeks under both HL and LL, with some exceptions due to leaf abscission or decline in total leaf area, possibly a strategy for water conservation.展开更多
Crack growth rate curves are the fundamental material property for metal structures under fatigue loading. Although there are many crack growth rate curves available in the literature, few of them showed the capabilit...Crack growth rate curves are the fundamental material property for metal structures under fatigue loading. Although there are many crack growth rate curves available in the literature, few of them showed the capability to explain various special phenomena observed in tests. A modified constitutive relation recently proposed by McEvily and his co-workers showed very promising capability. This modified constitutive relation is further generalized by (1) introducing an unstable fracture condition; (2) defining a virtual strength to replace the yield stress; and (3) defining an overload and underload parameter. The performances of this general constitutive relation for fatigue crack growth is extensively studied and it is found that this general constitutive relation is able to explain various phenomena observed with particular strong capability on load sequence effect.展开更多
In this paper, the general calculation formulas of radial matrix elements for relativistic n-dimensional hydrogen atom of spin S=0 are obtained, and the recurrence relation of different power order radial matrix eleme...In this paper, the general calculation formulas of radial matrix elements for relativistic n-dimensional hydrogen atom of spin S=0 are obtained, and the recurrence relation of different power order radial matrix elements are also derived.展开更多
Botanical, soil chemistry and soil microbiology variables were tested as predictors of in situ soil respiration rate in the various terrestrial habitats on sub-Antarctic Marion Island (47oS, 38oE). Inorganic P and tot...Botanical, soil chemistry and soil microbiology variables were tested as predictors of in situ soil respiration rate in the various terrestrial habitats on sub-Antarctic Marion Island (47oS, 38oE). Inorganic P and total N concentration were the best predictors amongst the chemistry variables and bacteria plate count the best of the microbiology variables. However, while these chemistry and microbiology variables could accurately predict soil respiration rate for particular habitats, they proved inadequate predictors across the whole range of habitats. The best suite of predictors comprised only botanical variables (relative covers of five plant guilds) and accounted for 94% of the total across-habitat variation in soil respiration rate. Mean field soil respiration rates (2.1 - 15.5 mmol CO2 m-2 h-1) for habitats not influenced by seabirds or seals are similar to rates in comparable Northern Hemisphere tundra habitats. Seabird and seal manuring enhances soil respiration rates to values (up to 27.6 mmol CO2 m-2 h-1) higher than found at any tundra site. Glucose, N, P or N plus P were added to three habitats with contrasting soil types;a fellfield with mineral, nutrient-poor soil, a mire with organic, nutrient-poor soil and a shore-zone herbfield heavily manured by penguins and with organic, nutrient-rich soil. Glucose addition stimulated soil respiration in the fellfield and mire (especially the former) but not in the coastal herbfield soil. N and P, alone or together, did not stimulate respiration at any of the habitats, but adding glucose to fellfield soils that had previously been fortified with P or NP caused a similar increase in respiration rate, which was greater than the increase when adding glucose to soils fortified only with N. This suggests that fellfield soil respiration is limited by P rather than N, and that there is no synergism between the two nutrients. For the mire and coastal herbfield, adding glucose to soils previously fortified with N, P or NP did not enhance rates more than adding glucose to soils that had received no nutrient pre-treatment.展开更多
Research on the multicomponent synergistic relationships between plants,litter,and soil from the perspective of ecological stoichiometry helps to understand nutrient cycling and distribution mechanisms within ecosyste...Research on the multicomponent synergistic relationships between plants,litter,and soil from the perspective of ecological stoichiometry helps to understand nutrient cycling and distribution mechanisms within ecosystems.This study focused on Juniperus saltuaria,the dominant tree species in the forestline ecotone of Sygera Mountains,southeastern Xizang,China.We systematically measured and analyzed the Carbon(C),nitrogen(N),and phosphorus(P)contents and their relationships in plants(leaves,branches,trunks,fine roots),litter(undecomposed layer,partially decomposed layer,fully decomposed layer),and soil(0-10 cm,10-20 cm,20-40 cm)at different slope positions.The results showed significant differences in the C,N,and P contents and stoichiometry of plants and soil at different slope positions,while no significant differences were observed among litter layers.At the same slope position,the C,N,and P contents in leaves and surface soil were the highest,with soil nutrients significantly decreasing with increasing depth.For litter,the C content in the undecomposed layer was significantly higher than that in the partially and fully decomposed layers while the P content showed the opposite trend.Surface soil(0-20 cm)exhibited a decoupled relationship with plants but a coupled relationship with litter while deep soil(20-40 cm)showed a coupled relationship with plants.J.saltuaria showed faster growth rates on uphill slope.In this study area,J.saltuaria exhibited consistent trends of N,P,and N:P ratios homeostasis across different slope positions and organs,with leaves and fine roots both limited by N.Significant interactive effects between plants,litter,and soil nutrients were observed across different slope positions.Positive correlations were found between leaf and litter,and between fine root and leaf while the relationships between litter and soil,and between soil and fine root,varied.This study helps improve our understanding of the nutrient interactions between plants,litter,and soil in dominant species of alpine forest ecosystems,as well as their ecological adaptation mechanisms.展开更多
Tropical peat swamp forest beds that have been reclaimed for agricultural use are generally an active source of nitrous oxide （N2O） efflux, however, the mechanism by which reclaimed tropical peat soils promote the e...Tropical peat swamp forest beds that have been reclaimed for agricultural use are generally an active source of nitrous oxide （N2O） efflux, however, the mechanism by which reclaimed tropical peat soils promote the emergence of N2O emitters in soil microbial communities remains unclear. The purpose of this study was to reveal the vertical distribution of N2O emission potential and its correlation with mineral nitrogen contents in reclaimed soils. Using a culture-based N2O emission assay, the N2O emission potentials of soil at various depths （0-450 cm） were investigated in two oil palm plantations in Sarawak, Malaysia, which had elapsed times of two years （E2Y） and 10 years （El 0Y） after deforestation, respectively. On the basis of the relationship between the vertical profiles of N2O emission potentials and the contents of mineralized nitrogen in the peat soils at various depths, the impact of land management on soil microbial communities was discussed. The peat soil at plantation site E2Y showed a trend of high N2O production in deep layers （200-400 cm）, whereas the older plantation site E10Y showed considerably more active N2O emission in shallow soil （10-50 cm）. N2O emission potentials among the soil microbial communities at different soil depths at the E10Y site showed positive correlations with NO3- and NH4＋ contents, whereas, soils obtained from the E2Y site had N2O emission potentials that were inversely proportional to the contents of NO3-. This contrasting vertical correlation between N2O-emitting potentials and mineralized nitrogen contents in bulk soils suggests that active N2O emission in deep soil at the E2Y site has maintained the original carbon-nitrogen （C/N） ratio of the peat soil, whereas at EIOY, such a regulatory system has been lost due to advanced soil degradation, leading to dynamic changes in the nitrogen cycle in shallow soil.展开更多
Distribution of different forms of sulphur(S)and carbon-nitrogen-sulphur relationships were studied in surface and subsurface soils of some tea growing areas of Northeastern India.The soils were strongly acidic in rea...Distribution of different forms of sulphur(S)and carbon-nitrogen-sulphur relationships were studied in surface and subsurface soils of some tea growing areas of Northeastern India.The soils were strongly acidic in reaction(pH-4.0 to 5.5),low to very high in organic carbon(4 to 54 g kg^-1),with cation exchange capacity(8.8 to 19.2 cmol(p+)kg^-1)and base saturation(50 to 77%).Organic S mostly contributed to the total-sulphur(62 to 77%)followed by Non sulphate S(28.8 to 37.2%)and sulphate S(0.7 to 1.4%).Except sulphate S,other forms of sulphur showed significant positive correlation among themselves as well as with organic carbon and total nitrogen.The C:N,C:S,N:S and C:N:S ratio varied from 8.2 to 10.0,6.18 to 71.57,0.62 to 7.26 and 100:10.1:1.4 to 100:12.2:16.2 respectively.Wider C:N:S ratios in all the surface and sub-surface soils indicated that the major portion of nitrogen and sulphur in tea growing soils of Northeastern India is locked up in organic combination which might pose as a potential threat towards tea plantation if application of sulphur is continuously ignored.展开更多
Objective To investigate the relationships between erythrocyte membrane n-6：n-3 PUFAs ratio and blood lipids and high sensitivity C-reactive protein （hs-CRP）. Methods The Chinese and a observational study consisted...Objective To investigate the relationships between erythrocyte membrane n-6：n-3 PUFAs ratio and blood lipids and high sensitivity C-reactive protein （hs-CRP）. Methods The Chinese and a observational study consisted of a population-based cross-sectiona subsequent 1-year follow-up study of 171 subjects with the fasting cholesterol of 5.13-8.00 mmol/L. study of 456 plasma total Results In the cross-sectional analysis, plasma low-density lipoprotein cholesterol （LDL-c） had a significant and negative association with the erythrocyte membrane n-6：n-3 PUFAs ratio （P for trend=0.019） after adjusting for sex, age and total PUFA percentage. In the follow-up study, 171 subjects were categorized into quartiles by the changes of n-6：n-3 ratio in erythrocyte membrane （△=month 12-month 0）. In the top quartile whose ratios of n-6：n-3 increased by an average of 1.25 during the follow-up, the LDL-c-lowering extent was 3.3 times of that in the lowest quartile whose ratios of n-6：n-3 decreased by an average of 1.13 （-1.07 mmol/L v.s. -0.32 mmol/L）. The hsCRP decreased by 0.11 mg/dL in the lowest quartile while increasing by 0.10 mg/dL in the top quartile （P for difference=0.052）. Conclusion Our results suggested that the balance between n-6 and n-3 fatty acids may optimize the cardiovascular benefits from dietary PUFAs.展开更多
Gilad Gour and Nolan R Wallach [J. Math. Phys. 51 112201(2010)] have proposed the 4-tangle and the square of the I concurrence. They also gave the relationship between the 4-tangle and the square of the I concurrence....Gilad Gour and Nolan R Wallach [J. Math. Phys. 51 112201(2010)] have proposed the 4-tangle and the square of the I concurrence. They also gave the relationship between the 4-tangle and the square of the I concurrence. In this paper, we give the expression of the square of the I concurrence and the n-tangle for six-qubit and eight-qubit by some local unitary transformation invariant. We prove that in six-qubit and eight-qubit states there exist strict monogamy laws for quantum correlations. We elucidate the relations between the square of the I concurrence and the n-tangle for six-qubit and eight-qubits. Especially, using this conclusion, we can show that 4-uniform states do not exist for eight-qubit states.展开更多
In this paper the following information interpretation of uncertainty relation is proposed: if one bit of information was extracted from the system as a result of the measurement process, then the measurement itself a...In this paper the following information interpretation of uncertainty relation is proposed: if one bit of information was extracted from the system as a result of the measurement process, then the measurement itself adds an additional uncertainty (chaos) into the system equaled to one bit. This formulation is developed by calculating of the Shannon information entropy for the classical N-slit interference experiment. This approach allows looking differently at several quantum phenomena. Particularly, the information interpretation is used for explanation of entangled photons diffraction picture compression.展开更多
文摘The oat panicle components were changed by the forms of nitrogen use influencing productivity. The aim of the study was to determine the direct and indirect effects of oat panicle components on grain yield by N-fertilizer rates in succession systems of high and reduced release of N-residual. The study was conducted in the years 2013 and 2014 in a randomized complete block with four replications in a factorial 3 × 2, for nitrogen rates (30, 60 and 120 kg·ha<sup>-1</sup>) and oat cultivars (Barbarasul and Brisasul) the soybean/oat and corn/oat systems. The panicle weight and grain per panicle show greater sensitivity to the change of nitrogen rates. Grain yield was favored by the direct effect of harvest index panicle and indirect by grain weight per panicle. In the system soybean/ oat, the grain weight of panicle shows greater efficiency in promoting positive direct effects on grain yield.
基金supported by the National Natural Science Foundation of China(31171479)the Key Laboratory Foundation of Jiangsu Province,China(10KJA210057)+2 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions,China,the Doctoral Advisor Foundation of Education Department of China(20113250110001)the Project of National Agricultural Modern Industrial Technology System Post Experts,China(CARS-18-20)the Graduate Student Scientific Research Innovation Projects of Jiangsu Province,China(CXLX11_1019)
文摘Expression of insecticidal protein for transgenic Bacillus thuringiensis （Bt） cotton is unstable and related to nitrogen metabolism. The objective of this study was to investigate the relationship between leaf carbon nitrogen ratio （C/N） and insecticidal efficacy of two Bt cotton cultivars. C/N ratio and Bt protein content were both measured at peak square period and peak boll period respectively under 5-7 d high temperature and different nitrogen fertilizer rates on the Yangzhou University Farm and the Ludong Cotton Farm, China. All plants were grown in field. The results showed that the C/N ratio enhanced slightly and the Bt protein content remained stable at peak square period, but significant increases for the C/N ratio and decreases markedly for the leaf Bt protein concentration were detected at the peak boll period. The similar patterns at the two growth periods were found for the leaf C/N ratio and Bt protein content by different N fertilizer treatments. When nitrogen rate was from 0 to 600 kg ha-l, the C/N ratio was reduced by 0.017 and 0.006 for Sikang 1 and Sikang 3 at peak square period, compared to the 1.350 to 1.143 reduction for Sikang 1 and Sikang 3 at peak boll period, respectively. Correspondingly, the leaf Bt protein contents were bolstered by 2.6-11.8 and 26.9-36.9% at the two different growth periods, respectively. The results suggested that enhanced C/N ratio by high temperature and nitrogen application may result in the reduction of inseetiocidal efficacy in Bt cotton, especially in peak boll period.
文摘There are abundant Bajocian—Tithonian bivalves in the main ridge of the Tanggula Mountains of northern Qinghai—Xizang Plateau, China. After figuring the common and coeval species between Tanggula and other areas (Fig. 1), and tracing the temporal and spacial historical distribution of the bivalves very capable of dispersion, some Jurassic bivalve biogeographic items, particularly the biogeographic relations, have been lit up. In the known 21 taxa of the Jurassic Pectinoida and Ostreoida from the main ridge of the Tanggula Mountains, there are 12 (57%) common and coeval species in northern Tethys, 13 (62%) common and coeval species in southern Tethys and 12 (57%) in Kachchh—southern Xizang area. It has demonstrated that there existed intermigration of bivalves between Tanggula and various parts of Tethys. Although there is no coeval species between Tanggula and western Australia, in these two areas there exist 6 (29%) close range common species of which 4 (19%) coevaity existed in western Australia and India Plate. Tanggula fauna is, therefore, still very close to that of western Australia. However, there are 15 (71%) common and 14 (67%) coevality species between the main ridge of the Tanggula Mountains and northwestern Europe, among the common species, 8 (38%) ones have lower limitation (first occurrence) in northwestern Europe but only 2 (10%) taxa are older in the main ridge of the Tanggula Mountains. It is very clear that pectinite and ostrea fauna of Tethys, particularly the main ridge of the Tanggula Mountains and Europe had very close relation and most Tanggula’s or northern Tethyan taxa migrated from northwestern Europe.
基金Supported by the National Basic Research Program (973 Program) of China (Nos.2010CB951704 and 2010CB833502)the National Natural Science Foundation for Young Scientists of China (No.30600070)the West Light Joint Scholarship of the Chinese Academy of Sciences
文摘In nutrient-limited alpine meadows,nitrogen(N) mineralization is prior to soil microbial immobilization;therefore,increased mineral N supply would be most likely immobilized by soil microbes due to nutrient shortage in alpine soils.In addition,low temperature in alpine meadows might be one of the primary factors limiting soil organic matter decomposition and thus N mineralization.A laboratory incubation experiment was performed using an alpine meadow soil from the Tibetan Plateau.Two levels of NH4NO3(N) or glucose(C) were added,with a blank without addition of C or N as the control,before incubation at 5,15,or 25 ℃ for 28 d.CO2 efflux was measured during the 28-d incubation,and the mineral N was measured at the beginning and end of the incubation,in order to test two hypotheses:1) net N mineralization is negatively correlated with CO2 efflux for the control and 2) the external labile N or C supply will shift the negative correlation to positive.The results showed a negative correlation between CO2 efflux and net N immobilization in the control.External inorganic N supply did not change the negative correlation.The external labile C supply shifted the linear correlation from negative to positive under the low C addition level.However,under the high C level,no correlation was found.These suggested that the correlation of CO2 efflux to net N mineralization strongly depend on soil labile C and C:N ratio regardless of temperatures.Further research should focus on the effects of the types and the amount of litter components on interactions of C and N during soil organic matter decomposition.
基金supported by the National Key Research and Development Program of China(No.2017YFC0404401)the Central Public-interest Scientific Institution Basal Research Fund(No.HKY-JBYW-2018-07)。
文摘Salinization in estuarine wetlands significantly alters the balance between their nitrogen(N)removal and retention abilities but these processes have not yet been characterized effectively.In the present study,the potential rates of sediment denitrification,anaerobic ammonium oxidation(anammox),and dissimilatory nitrate reduction to ammonium(DNRA)were mapped using N isotope tracing methods along salinity gradients across the Yellow River Delta wetland(YRDW)in China.The contribution of anammox to total dissimilatory N transformations in YRDW was merely 6.8%,whereas denitrification and DNRA contributed 52.3%and 40.9%,respectively.The potential rate of denitrification(5.82μmol/kg/h)decreased significantly along salinity gradients and markedly exceeded DNRA potential rate(2.7μmol/kg/h)in fresh wetlands,but was lower than that of DNRA in oligohaline wetlands(3.06 and 3.18μmol/kg/h,respectively).Moreover,a significantly positive relationship between salinity and DNRA/denitrification was obeserved,indicating that increased salinity may favor DNRA over denitrification.Furthermore,total sulfur(TS)content and ratio of total organic carbon to total nitrogen(C/N)increased with the salinity gradient and showed evident positive relationships with the DNRA/denitrification ratio.In this study,we proved that increased salinization resulted in the dominance of DNRA over denitrification,possible through the addition of S and alteration of the C/N in estuarine wetlands,leading to increased N retention in estuarine wetlands during salinization,which would enhance the eutrophication potential within wetlands and in downstream ecosystems.
基金Supported by the National Natural Science Foundation of China(No.41090280)
文摘Rapid nitrogen(N) transformations and losses occur in the rice rhizosphere through root uptake and microbial activities. However,the relationships between rice roots and rhizosphere microbes for N utilization are still unclear. We analyzed different N forms(NH+4,NO-3, and dissolved organic N), microbial biomass N and C, dissolved organic C, CH4 and N2O emissions, and abundance of microbial functional genes in both rhizosphere and bulk soils after 37-d rice growth in a greenhouse pot experiment. Results showed that the dissolved organic C was significantly higher in the rhizosphere soil than in the non-rhizosphere bulk soil, but microbial biomass C showed no significant difference. The concentrations of NH+4, dissolved organic N, and microbial biomass N in the rhizosphere soil were significantly lower than those of the bulk soil, whereas NO-3in the rhizosphere soil was comparable to that in the bulk soil. The CH4 and N2O fluxes from the rhizosphere soil were much higher than those from the bulk soil. Real-time polymerase chain reaction analysis showed that the abundance of seven selected genes, bacterial and archaeal 16 S rRNA genes, amoA genes of ammonia-oxidizing archaea and ammonia-oxidizing bacteria, nosZ gene, mcrA gene, and pmoA gene, was lower in the rhizosphere soil than in the bulk soil, which is contrary to the results of previous studies. The lower concentration of N in the rhizosphere soil indicated that the competition for N in the rhizosphere soil was very strong, thus having a negative effect on the numbers of microbes. We concluded that when N was limiting, the growth of rhizosphere microorganisms depended on their competitive abilities with rice roots for N.
基金the Major State Basic Research of China(Grant No.G1999012011) the National High Technology Research and Development Program of China(2002AA648010).
文摘Nine enclosures (5 m x 5 m) were built in a Fenneropenaeus chinensis culture pond of Rushan Gulf in April, 2001. The probiotics and BIO ENERGIZER solution were applied for disparate treatments. Variations of alkaline phosphatase ac- tivity (APA) and its relationship with the contents of C, N and P in sediments were studied. Results show that APA of sedi- ments increases from 3.096 nmolg-1min-1 to 5.407 nmol g-1min-1 in culture period; the bacteria biomass is not the only factor to determine APA; the contents of total P and total organic carbon have a significant positive correlation with APA, while that of total nitrogen has a negative correlation. In addition, the contents of inorganic P and organic P are not regular with APA. By comparison, TOC shows a more significant coherence with APA, meaning that organic pollution in sediments af- fects APA remarkably.
文摘Native orchid species of Singapore in their natural conditions experience stress from high irradiance, high temperatures and periods of extended low rainfall, which impact orchid plant physiology and lead to reduced growth and productivity. In this study, it was found that there was a reduction in photochemical efficiency of photosystem II (PSII) in 6 native orchid species under high light (HL) and Bulbophyllum membranaceum under low light (LL). There was chronic photoinhibition in these 6 orchid species over a period of 3 months after transplanting onto the tree trunks without watering and fertilization, especially in Coelogynes mayeriana and Bulbophyllum membranaceum under both HL and LL. This chronic photoinhibition caused by sustained period of water deficit in their natural conditions was later reversed by natural re-watering conditions from higher rainfall. These results indicate that water deficit has a greater impact on photosynthetic light utilization efficiency than excess light. The present study also showed that after natural rewatering, relative water content (RWC) of leaves and pseudobulbs generally increased. During the natural re-watering, total leaf area also gradually increased and reached maximum expansion after 7 weeks under both HL and LL, with some exceptions due to leaf abscission or decline in total leaf area, possibly a strategy for water conservation.
文摘Crack growth rate curves are the fundamental material property for metal structures under fatigue loading. Although there are many crack growth rate curves available in the literature, few of them showed the capability to explain various special phenomena observed in tests. A modified constitutive relation recently proposed by McEvily and his co-workers showed very promising capability. This modified constitutive relation is further generalized by (1) introducing an unstable fracture condition; (2) defining a virtual strength to replace the yield stress; and (3) defining an overload and underload parameter. The performances of this general constitutive relation for fatigue crack growth is extensively studied and it is found that this general constitutive relation is able to explain various phenomena observed with particular strong capability on load sequence effect.
文摘In this paper, the general calculation formulas of radial matrix elements for relativistic n-dimensional hydrogen atom of spin S=0 are obtained, and the recurrence relation of different power order radial matrix elements are also derived.
文摘Botanical, soil chemistry and soil microbiology variables were tested as predictors of in situ soil respiration rate in the various terrestrial habitats on sub-Antarctic Marion Island (47oS, 38oE). Inorganic P and total N concentration were the best predictors amongst the chemistry variables and bacteria plate count the best of the microbiology variables. However, while these chemistry and microbiology variables could accurately predict soil respiration rate for particular habitats, they proved inadequate predictors across the whole range of habitats. The best suite of predictors comprised only botanical variables (relative covers of five plant guilds) and accounted for 94% of the total across-habitat variation in soil respiration rate. Mean field soil respiration rates (2.1 - 15.5 mmol CO2 m-2 h-1) for habitats not influenced by seabirds or seals are similar to rates in comparable Northern Hemisphere tundra habitats. Seabird and seal manuring enhances soil respiration rates to values (up to 27.6 mmol CO2 m-2 h-1) higher than found at any tundra site. Glucose, N, P or N plus P were added to three habitats with contrasting soil types;a fellfield with mineral, nutrient-poor soil, a mire with organic, nutrient-poor soil and a shore-zone herbfield heavily manured by penguins and with organic, nutrient-rich soil. Glucose addition stimulated soil respiration in the fellfield and mire (especially the former) but not in the coastal herbfield soil. N and P, alone or together, did not stimulate respiration at any of the habitats, but adding glucose to fellfield soils that had previously been fortified with P or NP caused a similar increase in respiration rate, which was greater than the increase when adding glucose to soils fortified only with N. This suggests that fellfield soil respiration is limited by P rather than N, and that there is no synergism between the two nutrients. For the mire and coastal herbfield, adding glucose to soils previously fortified with N, P or NP did not enhance rates more than adding glucose to soils that had received no nutrient pre-treatment.
基金funded by the National Ministry of Science and Technology Ecological Station(LZF2020-2025)the Longterm Ecological Observation Study of Alpine Pine in Southeast Tibet(Science and Technology Innovation Base)(XZ202301JD0001G)+1 种基金the Graduate Student Innovation Project of Tibet Agriculture and Animal Husbandry College(YJS2023-01)the Tibet Agriculture and Animal Husbandry College Talent Team Development Fund Project(XZNMXYRCXM-2024-10).
文摘Research on the multicomponent synergistic relationships between plants,litter,and soil from the perspective of ecological stoichiometry helps to understand nutrient cycling and distribution mechanisms within ecosystems.This study focused on Juniperus saltuaria,the dominant tree species in the forestline ecotone of Sygera Mountains,southeastern Xizang,China.We systematically measured and analyzed the Carbon(C),nitrogen(N),and phosphorus(P)contents and their relationships in plants(leaves,branches,trunks,fine roots),litter(undecomposed layer,partially decomposed layer,fully decomposed layer),and soil(0-10 cm,10-20 cm,20-40 cm)at different slope positions.The results showed significant differences in the C,N,and P contents and stoichiometry of plants and soil at different slope positions,while no significant differences were observed among litter layers.At the same slope position,the C,N,and P contents in leaves and surface soil were the highest,with soil nutrients significantly decreasing with increasing depth.For litter,the C content in the undecomposed layer was significantly higher than that in the partially and fully decomposed layers while the P content showed the opposite trend.Surface soil(0-20 cm)exhibited a decoupled relationship with plants but a coupled relationship with litter while deep soil(20-40 cm)showed a coupled relationship with plants.J.saltuaria showed faster growth rates on uphill slope.In this study area,J.saltuaria exhibited consistent trends of N,P,and N:P ratios homeostasis across different slope positions and organs,with leaves and fine roots both limited by N.Significant interactive effects between plants,litter,and soil nutrients were observed across different slope positions.Positive correlations were found between leaf and litter,and between fine root and leaf while the relationships between litter and soil,and between soil and fine root,varied.This study helps improve our understanding of the nutrient interactions between plants,litter,and soil in dominant species of alpine forest ecosystems,as well as their ecological adaptation mechanisms.
文摘Tropical peat swamp forest beds that have been reclaimed for agricultural use are generally an active source of nitrous oxide （N2O） efflux, however, the mechanism by which reclaimed tropical peat soils promote the emergence of N2O emitters in soil microbial communities remains unclear. The purpose of this study was to reveal the vertical distribution of N2O emission potential and its correlation with mineral nitrogen contents in reclaimed soils. Using a culture-based N2O emission assay, the N2O emission potentials of soil at various depths （0-450 cm） were investigated in two oil palm plantations in Sarawak, Malaysia, which had elapsed times of two years （E2Y） and 10 years （El 0Y） after deforestation, respectively. On the basis of the relationship between the vertical profiles of N2O emission potentials and the contents of mineralized nitrogen in the peat soils at various depths, the impact of land management on soil microbial communities was discussed. The peat soil at plantation site E2Y showed a trend of high N2O production in deep layers （200-400 cm）, whereas the older plantation site E10Y showed considerably more active N2O emission in shallow soil （10-50 cm）. N2O emission potentials among the soil microbial communities at different soil depths at the E10Y site showed positive correlations with NO3- and NH4＋ contents, whereas, soils obtained from the E2Y site had N2O emission potentials that were inversely proportional to the contents of NO3-. This contrasting vertical correlation between N2O-emitting potentials and mineralized nitrogen contents in bulk soils suggests that active N2O emission in deep soil at the E2Y site has maintained the original carbon-nitrogen （C/N） ratio of the peat soil, whereas at EIOY, such a regulatory system has been lost due to advanced soil degradation, leading to dynamic changes in the nitrogen cycle in shallow soil.
文摘Distribution of different forms of sulphur(S)and carbon-nitrogen-sulphur relationships were studied in surface and subsurface soils of some tea growing areas of Northeastern India.The soils were strongly acidic in reaction(pH-4.0 to 5.5),low to very high in organic carbon(4 to 54 g kg^-1),with cation exchange capacity(8.8 to 19.2 cmol(p+)kg^-1)and base saturation(50 to 77%).Organic S mostly contributed to the total-sulphur(62 to 77%)followed by Non sulphate S(28.8 to 37.2%)and sulphate S(0.7 to 1.4%).Except sulphate S,other forms of sulphur showed significant positive correlation among themselves as well as with organic carbon and total nitrogen.The C:N,C:S,N:S and C:N:S ratio varied from 8.2 to 10.0,6.18 to 71.57,0.62 to 7.26 and 100:10.1:1.4 to 100:12.2:16.2 respectively.Wider C:N:S ratios in all the surface and sub-surface soils indicated that the major portion of nitrogen and sulphur in tea growing soils of Northeastern India is locked up in organic combination which might pose as a potential threat towards tea plantation if application of sulphur is continuously ignored.
基金supported by research grants from the National Natural Science Foundation of China (30872102)the Diet Nutrition Research & Communication Grant of Danone Institute China (DIC2008‐12)
文摘Objective To investigate the relationships between erythrocyte membrane n-6：n-3 PUFAs ratio and blood lipids and high sensitivity C-reactive protein （hs-CRP）. Methods The Chinese and a observational study consisted of a population-based cross-sectiona subsequent 1-year follow-up study of 171 subjects with the fasting cholesterol of 5.13-8.00 mmol/L. study of 456 plasma total Results In the cross-sectional analysis, plasma low-density lipoprotein cholesterol （LDL-c） had a significant and negative association with the erythrocyte membrane n-6：n-3 PUFAs ratio （P for trend=0.019） after adjusting for sex, age and total PUFA percentage. In the follow-up study, 171 subjects were categorized into quartiles by the changes of n-6：n-3 ratio in erythrocyte membrane （△=month 12-month 0）. In the top quartile whose ratios of n-6：n-3 increased by an average of 1.25 during the follow-up, the LDL-c-lowering extent was 3.3 times of that in the lowest quartile whose ratios of n-6：n-3 decreased by an average of 1.13 （-1.07 mmol/L v.s. -0.32 mmol/L）. The hsCRP decreased by 0.11 mg/dL in the lowest quartile while increasing by 0.10 mg/dL in the top quartile （P for difference=0.052）. Conclusion Our results suggested that the balance between n-6 and n-3 fatty acids may optimize the cardiovascular benefits from dietary PUFAs.
文摘Gilad Gour and Nolan R Wallach [J. Math. Phys. 51 112201(2010)] have proposed the 4-tangle and the square of the I concurrence. They also gave the relationship between the 4-tangle and the square of the I concurrence. In this paper, we give the expression of the square of the I concurrence and the n-tangle for six-qubit and eight-qubit by some local unitary transformation invariant. We prove that in six-qubit and eight-qubit states there exist strict monogamy laws for quantum correlations. We elucidate the relations between the square of the I concurrence and the n-tangle for six-qubit and eight-qubits. Especially, using this conclusion, we can show that 4-uniform states do not exist for eight-qubit states.
文摘In this paper the following information interpretation of uncertainty relation is proposed: if one bit of information was extracted from the system as a result of the measurement process, then the measurement itself adds an additional uncertainty (chaos) into the system equaled to one bit. This formulation is developed by calculating of the Shannon information entropy for the classical N-slit interference experiment. This approach allows looking differently at several quantum phenomena. Particularly, the information interpretation is used for explanation of entangled photons diffraction picture compression.
