Ammonia (NH3) volatilization, denitrification loss, and nitrous oxide (N2O) emission were investigated from an irrigated wheat-maize rotation field on the North China Plain, and the magnitude of gaseous N loss from de...Ammonia (NH3) volatilization, denitrification loss, and nitrous oxide (N2O) emission were investigated from an irrigated wheat-maize rotation field on the North China Plain, and the magnitude of gaseous N loss from denitrification and NH3 volatilization was assessed. The micrometeorological gradient diffusion method in conjunction with a Bowen Ratio system was utilized to measure actual NH3 fluxes over a large area, while the acetylene inhibition technique (intact soil cores) was employed for measurement of denitrification losses and N2O emissions. Ammonia volatilization loss was 26.62% of the applied fertilizer nitrogen (N) under maize, while 0.90% and 15.55% were lost from the wheat field at sowing and topdressing, respectively. The differences in NH3 volatilization between different measurement events may be due to differences between the fertilization methods, and to differences in climatic conditions such as soil temperature.Denitrification losses in the fertilized plots were 0.67%-2.87% and 0.31%-0.49% of the applied fertilizer N under maize and wheat after subtracting those of the controls, respectively. Nitrous oxide emissions in the fertilized plots were approximately 0.08%-0.41% and 0.26%-0.34% of the applied fertilizer N over the maize and wheat seasons after subtracting those of the controls, correspondingly. The fertilizer N losses due to NH3 volatilization were markedly higher than those through denitrification and nitrous oxide emissions. These results indicated that NH3 volatilization was an important N transformation in the crop-soil system and was likely to be the major cause of low efficiencies with N fertilizer in the study area. Denitrification was not a very important pathway of N fertilizer loss, but did result in important evolution of the greenhouse gas N2O and the effect of N2O emitted from agricultural fields on environment should not be overlooked.展开更多
AIM： To examine the association of inducible nitric oxide synthase （iNOS） C150T polymorphism with gastric cancer, as well as with gastric atrophy and H pylori seropositivity.METHODS： A single nucleotide polymorphi...AIM： To examine the association of inducible nitric oxide synthase （iNOS） C150T polymorphism with gastric cancer, as well as with gastric atrophy and H pylori seropositivity.METHODS： A single nucleotide polymorphism of iNOS CtSOT was examined for 454 Japanese health checkup examinees （126 males and 328 females） aged 35 to 85 years without a history of cancer and 202 gastric cancer patients （134 males and 68 females） aged 33 to 94 years with pathologically confirmed diagnosis of gastric adenocarcinoma.RESULTS： The iNOS C150T polymorphism was not associated with gastric atrophy or with H pylori seropositivity. The odds ratio （OR） of the C/T ＋T/T for gastric cancer was increased without statistical significance （OR=1.19, 95% confidence interval （CI）： 0.68-2.08）. In the differentiated subgroup （n = 113）, however, the OR of the C/T genotvpe for gastric cancer was significant （OR = 2.02, 95% CI： 1.04-3.92） relative to the C/C genotype. In addition, considering the location of gastric cancer （n = 105）, there were significant differences between the controls and non-cardia group with the ORof 2.13 （95% CI： 1.08-4.18） for C/T and 1.94 （95% CI： 1.00-3.78） for C/T ＋ T/T.CONCLUSION： The iNOS C150T polymorphism is associated with the risk of H pylori-related gastric cancer in a Japanese population. This polymorphism may play an important role in increasing the risk of gastric cancer in Asian countires with the highest rates of gastric cancer.展开更多
Concentrations of atmospheric nitrous oxide （N2O）, a potent greenhouse gas, have been continuously increasing, and cropland soils are one of the largest sources of N2O. Variations in environmental and anthropogenic ...Concentrations of atmospheric nitrous oxide （N2O）, a potent greenhouse gas, have been continuously increasing, and cropland soils are one of the largest sources of N2O. Variations in environmental and anthropogenic factors have substantial impacts on both the frequency and magnitude of N2O emissions. Based on measurements from a wheat-maize system in the North China Plain, the authors parameterized the Agricultural Production Systems Simulator （APSIM） model, which was initially developed in Australia, for simulating N2O emissions under different agricultural management practices. After calibrating one of the key parameters -- the fraction of N2O lost in nitrification （k2） -- the results showed that the model successfully captured the daily N2O fluxes under different nitrogen fertilization treatments, but underestimated some large peak fluxes. By pooling all data together, the calibrated APSIM model also performed well in representing cumulative N2O emissions under various treatments at annual and finer （monthly and daily） time scales.展开更多
Photocatalytic hydrogen peroxide(H_(2)O_(2))production is a promising strategy to replace the traditional production processes;however,the inefficient H_(2)O_(2) productivity limits its application.In this study,oxyge...Photocatalytic hydrogen peroxide(H_(2)O_(2))production is a promising strategy to replace the traditional production processes;however,the inefficient H_(2)O_(2) productivity limits its application.In this study,oxygen-rich g-C_(3)N_(4) with abundant nitrogen vacancies(OCN)was synthesized for photocatalytic H_(2)O_(2) production.X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy indicated that oxygen-containing functional groups(–COOH and C–O–C)were obtained.Electron paramagnetic resonance confirmed the successful introduction of nitrogen vacancies.OCN exhibited efficient photocatalytic H_(2)O_(2) production performance of 1965μmol L^(−1) h^(−1) in air under visible-light irradiation.The high H_(2)O_(2) production was attributed to the enhanced adsorption of oxygen,enlarged specific surface area,and promoted carrier separation.An increased H_(2)O_(2) production rate(5781μmol L^(−1) h^(−1))was achieved in a Na_(3)PO_(4) solution.The improved performance was attributed to the changed reactive oxygen species.Specifically,the adsorbed PO_(4)^(3−) on the surface of the OCN promoted the transfer of holes to the catalyst surface.•O_(2)−obtained by O_(2) reduction reacted with adjacent holes to generate 1O_(2),which could efficiently generate H_(2)O_(2) with isopropanol.Additionally,PO_(4)^(3−),as a stabilizer,inhibited the decomposition of H_(2)O_(2).展开更多
The measurement of CO2 and N2O effiux from forest soils is of great importance in evaluating the role of forests as sequestering agents of atmospheric CO2 and nitrogen. To quantify the effect of site on temperature de...The measurement of CO2 and N2O effiux from forest soils is of great importance in evaluating the role of forests as sequestering agents of atmospheric CO2 and nitrogen. To quantify the effect of site on temperature dependence of net C-mineralization and N2O-N emissions, three adjacent forest floors under beech, Norway spruce and mixed species stands were investigated at Soiling forest, Germany, by an incubation experiment for three months. The investigated net C-mineralization and N2O-N emissions from all forest floors exhibited an exponential increase with respect to temperature elevation. The temperature coefficient function （Q10 value）, was fitted to flux rates to describe the temperature sensitivity of forest floors on temperature in the range of 1-20℃. Comparing the fitted curves for temperature sensitivity of the forest floors in relation to net carbon mineralization and nitrous oxide emission rates revealed a strong positive correlation across all sites. For the whole data set of all stands, a Q10 value of 1.73-2.10 for net C-mineralization and 2.81-3.58 for N2O-N emissions per measured unit was found to describe the temperature dependency of net C-mineralization and N20-N efflux at experimental site. The absence of clear differences between beech and spruce in mono and mixed species cultures on temperature dependencies of net C-mineralization and N2O-N emission rates indicated that the flux rates were not affected by species-specific differences of litter quality.展开更多
Eutrophication and climate change, key environmental concerns, are both linked to the carbon and nitrogen cycles hence the improved understanding of these cycles is essential. Currently, there is no system that simult...Eutrophication and climate change, key environmental concerns, are both linked to the carbon and nitrogen cycles hence the improved understanding of these cycles is essential. Currently, there is no system that simultaneously measures the fluxes of the three key gas phase products of nitrogen and carbon cycling （CO2, CH4 and N2O） in submerged ecosystems with hourly time resolution. A ＂Lake-in-a-box＂ （mesocosm） was developed in the laboratory which allowed the monitoring of key components of the carbon and nitrogen cycles within the air, water and sediments. The approach is automated, simple and time efficient and novel in its ability to examine many different carbon and nitrogen compounds in all three physical component of the ＂lake＂. Dramatic fluctuations in gaseous flux and the concentrations of overlying water and sedimentary carbon and nitrogen compounds were noted over a three week period. These were split into five distinct phases which were linked to changes in sedimentary N and C cycling. The results highlighted the important of links between the two cycles and supported recent studies showing that estuarine sediments can act as both a source and a sink of nitrogen.展开更多
[Objective] The aim was to study on response of N2O emissions of farm- land ecosystem on temperature rising. [Methed] In farmland ecosystem in Huaibei City in Anhui Province, N2O emission by twelve varieties of crop o...[Objective] The aim was to study on response of N2O emissions of farm- land ecosystem on temperature rising. [Methed] In farmland ecosystem in Huaibei City in Anhui Province, N2O emission by twelve varieties of crop on temperature was researched with DeNitrification-DeComposition （NDC）. [Result] Response of dry- land crop on temperature rising can be divided into three categories, as follows： The first category, N2O emission of crop changed little during the temperature increasing, for example, from 0 to 3 %;, the emissions by potatoes, cotton, maize and rapeseed increased little and decreased little when temperature changed from 1.5 to 3 ℃. Crops of the second category declined with temperature increasing in N2O emission, for example, N2O emission decreased by 8.1% with temperature increasing from 0 to 3 ℃, including sugar cane, tobacco, wheat, soybean and pea. In third category, N2O emission of crop grew with temperature increasing, for example, the emission of rice, vegetables and fruit trees increased by 22.8% when the temperature grew from 0 to 3 ℃. [Conclusion] The research indicated that N2O emission in ecosystem of drv farmland increased little with temoerature risina.展开更多
垃圾填埋场是重要的甲烷释放源,其有效管理是减缓温室效应的重要环节.通过硝化渗滤液回灌模拟垃圾填埋柱,研究硝化渗滤液在新鲜垃圾和老龄垃圾填埋柱中的脱氮及对垃圾稳定化和产甲烷的影响.结果表明,回灌的硝化渗滤液在不同填埋龄垃圾柱...垃圾填埋场是重要的甲烷释放源,其有效管理是减缓温室效应的重要环节.通过硝化渗滤液回灌模拟垃圾填埋柱,研究硝化渗滤液在新鲜垃圾和老龄垃圾填埋柱中的脱氮及对垃圾稳定化和产甲烷的影响.结果表明,回灌的硝化渗滤液在不同填埋龄垃圾柱中,均可实现总氧化态氮(Total oxidation nitroge,TON)完全还原.当回灌TON负荷分别达到14.19 g t-1(TS)d-1和10.45 g t-1(TS)d-1时,新、老垃圾柱中甲烷产生开始受到抑制.实验后期,回灌TON负荷增至38.78 g t-1(TS)d-1和30.62 g t-1(TS)d-1时,新、老垃圾填埋柱产甲烷相对抑制率分别达54.10%和95.77%.同时,回灌反硝化对新、老垃圾柱中垃圾降解贡献率(Rd)分别达85%和93%,能有效促进垃圾稳定.展开更多
Objective To investigate the effect of oral administration of arginine on linear growth of long bones in male pubertal rats and the underlying mechanisms, focusing on expression of genes related to the hypothalamus-pi...Objective To investigate the effect of oral administration of arginine on linear growth of long bones in male pubertal rats and the underlying mechanisms, focusing on expression of genes related to the hypothalamus-pituitary growth axis and the nitric oxide （NO）-cyclic guanosine monophosphate （cGMP） pathway. Methods Rats were randomly divided into control and intervention groups. In the intervention group, arginine was solved in water （0.045 g L-arginine was mixed with 1 mL water） and administered in rats （10 mL/kg） through gastric perfusion once per day, for totally 28 d. Rats in the control group received normal saline treatment. Bone histomorphometry analysis was used to measure growth plate width and mineral apposition rate of the tibia, as well as trabecular bone volume fraction, osteoblast surface and osteo- clast surface of the femur. Serum growth hormone （GH） concentration was determined by radioimmunoassay. Real-time PCR was used to measure the expression of neuronal nitric oxide synthase （nNOS）, soluble guanylyl cyclases （sGCal and sGCfll）, growth hormone-releasing hormone （Ghrh） and somatostatin （SS） in hypothalamus, as well as Gh in pituitary. Western blot was used to detect the protein levels ofnNOS, sGCα1 and sGCβ1 in hypothalamus. Results After treat- ment with arginine, the growth plate width of tibia and osteoblast surface of femur were increased （P 〈 0.05）, and serum GH concentration was elevated （P 〈 0.05）. Besides, mRNA and protein levels ofnNOS and sGCα1 （P 〈 0.05）, as well as the expression of Gh mRNA （P 〈 0.01）, were significantly up-regulated, while the expression of SS mRNA was down- regulated （P 〈 0.05）. Conclusion Oral administration ofarginine could improve linear growth of long bones by regulating mRNA expression of SS and Gh and inducing GH secretion, possibly via nNOS-NO-sGC-cGMP signal transduction pathway.展开更多
Objective： To investigate the relationships between endothelial nitric oxide synthases （eNOS） G894T and 27 bpvariable number tandem repeat （VNTR） gene polymorphisms and osteoporosis in the postmenopausal women of...Objective： To investigate the relationships between endothelial nitric oxide synthases （eNOS） G894T and 27 bpvariable number tandem repeat （VNTR） gene polymorphisms and osteoporosis in the postmenopausal women of Chinese Han nationality. Methods： In the present study, 281 postmenopausal women from Xi＇an urban area in West China were recruited, and divided into osteoporosis, osteopenia, and normal groups according to the diagnostic criteria of osteoporosis proposed by World Health Organization （WHO）. The bone mineral density （BMD） values of lumbar vertebrae and left hips were determined by QDR-2000 dual energy X-ray absorptiometry. Blood samples were tested for plasma biochemical indicators including testosterone, estradiol, calcitonin, osteocalcin, and procollagen type I amino-terminal propeptide by enzyme-linked immunosorbent assay （ELISA）, tartrate-resistant acid phosphatase by spectrophotometric method, and the content of nitric oxide by Griess method. Genome DNA was extracted from whole blood, and G894T polymorphism of eNOS gene was analyzed by using polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） method and 27 bp-VNTR polymorphism of eNOS gene was genotyped by PCR method. Then the relationships between genotypes and biochemical indicators, genotypes and osteoporosis, and haplotypes and osteoporosis were analyzed. Results： The average BMD values of the femoral neck, ward＇s triangle and lumbar vertebrae 1-4 （LI-L4） in the subjects with T/T genotype in eNOS G894T locus were significantly higher than those in the subjects with G/T and G/G genotypes （P〈0.05）. The average BMD of the femoral neck in the subjects with a/a genotype of eNOS 27 bp-VNTR locus was evidently higher than that in the subjects with b/b genotype （P〈0.05）. The plasma testosterone and osteocalcin concentrations in the subjects of eNOS G894T G/T genotype were evidently higher than those in the subjects of other genotypes （P〈0.05）; the plasma estradiol concentration in the subjects of eNOS 27 bp-VNTR a/a genotype was obviously higher than that in the subjects of b/b genotype （P〈0.01）. eNOS G/G homozygous frequencies in osteoporosis women, osteopenia women, and normal women were 85.37%, 76.38%, and 83.87%, respectively （P〉0.05）. 0% osteoporosis woman, 0.79% osteopenia women, and 3.23% normal women were eNOS a/a homozygous （P〈0.05）. The frequencies of eNOS 27 bp-VNTR a allele were 5.33% in the osteoporosis group, 10.24% in the osteopenia group, and 16.13% in the normal group （P〈0.05, odds ratio （OR）=0.29, 95% confidence interval （CI）=0.11-0.77）, suggesting that a/a genotype and a allele might have protective effects on osteoporosis. The haplotype analysis showed that G-b was 87.7% （214/244） in the osteoporosis group （P〈0.05, OR=2.48, 95% CI=1. 18-5.18）. G-a was 5.3% （13/244） in the osteoporosis group （P〈0.05, OR=0.29, 95% CI=0. 11-0.77）. G-b was a risk factor for osteoporosis, and G-a a protective factor. Conclusion： eNOS G894T G/T genotype influenced the plasma testosterone and osteocalcin concentrations, and T/T genotype influenced BMD. eNOS 27 bp-VNTR a/a genotype increased plasma estradiol concentration to have a protective effect on osteoporosis.展开更多
基金Project supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (No. KZCX2-413-3)the National Key Basic Research Support Foundation (NKBRSF) of China (No. G1999011803) the Australian Centre for
文摘Ammonia (NH3) volatilization, denitrification loss, and nitrous oxide (N2O) emission were investigated from an irrigated wheat-maize rotation field on the North China Plain, and the magnitude of gaseous N loss from denitrification and NH3 volatilization was assessed. The micrometeorological gradient diffusion method in conjunction with a Bowen Ratio system was utilized to measure actual NH3 fluxes over a large area, while the acetylene inhibition technique (intact soil cores) was employed for measurement of denitrification losses and N2O emissions. Ammonia volatilization loss was 26.62% of the applied fertilizer nitrogen (N) under maize, while 0.90% and 15.55% were lost from the wheat field at sowing and topdressing, respectively. The differences in NH3 volatilization between different measurement events may be due to differences between the fertilization methods, and to differences in climatic conditions such as soil temperature.Denitrification losses in the fertilized plots were 0.67%-2.87% and 0.31%-0.49% of the applied fertilizer N under maize and wheat after subtracting those of the controls, respectively. Nitrous oxide emissions in the fertilized plots were approximately 0.08%-0.41% and 0.26%-0.34% of the applied fertilizer N over the maize and wheat seasons after subtracting those of the controls, correspondingly. The fertilizer N losses due to NH3 volatilization were markedly higher than those through denitrification and nitrous oxide emissions. These results indicated that NH3 volatilization was an important N transformation in the crop-soil system and was likely to be the major cause of low efficiencies with N fertilizer in the study area. Denitrification was not a very important pathway of N fertilizer loss, but did result in important evolution of the greenhouse gas N2O and the effect of N2O emitted from agricultural fields on environment should not be overlooked.
基金Supported by a Grant-in-Aid for Scientific Research on Special Priority Areas of Cancer from the Japanese Ministry of Education, Culture, Sports, Science and Technology
文摘AIM： To examine the association of inducible nitric oxide synthase （iNOS） C150T polymorphism with gastric cancer, as well as with gastric atrophy and H pylori seropositivity.METHODS： A single nucleotide polymorphism of iNOS CtSOT was examined for 454 Japanese health checkup examinees （126 males and 328 females） aged 35 to 85 years without a history of cancer and 202 gastric cancer patients （134 males and 68 females） aged 33 to 94 years with pathologically confirmed diagnosis of gastric adenocarcinoma.RESULTS： The iNOS C150T polymorphism was not associated with gastric atrophy or with H pylori seropositivity. The odds ratio （OR） of the C/T ＋T/T for gastric cancer was increased without statistical significance （OR=1.19, 95% confidence interval （CI）： 0.68-2.08）. In the differentiated subgroup （n = 113）, however, the OR of the C/T genotvpe for gastric cancer was significant （OR = 2.02, 95% CI： 1.04-3.92） relative to the C/C genotype. In addition, considering the location of gastric cancer （n = 105）, there were significant differences between the controls and non-cardia group with the ORof 2.13 （95% CI： 1.08-4.18） for C/T and 1.94 （95% CI： 1.00-3.78） for C/T ＋ T/T.CONCLUSION： The iNOS C150T polymorphism is associated with the risk of H pylori-related gastric cancer in a Japanese population. This polymorphism may play an important role in increasing the risk of gastric cancer in Asian countires with the highest rates of gastric cancer.
基金supported by the National Natural Science Foundation of China[grant number 41590875]
文摘Concentrations of atmospheric nitrous oxide （N2O）, a potent greenhouse gas, have been continuously increasing, and cropland soils are one of the largest sources of N2O. Variations in environmental and anthropogenic factors have substantial impacts on both the frequency and magnitude of N2O emissions. Based on measurements from a wheat-maize system in the North China Plain, the authors parameterized the Agricultural Production Systems Simulator （APSIM） model, which was initially developed in Australia, for simulating N2O emissions under different agricultural management practices. After calibrating one of the key parameters -- the fraction of N2O lost in nitrification （k2） -- the results showed that the model successfully captured the daily N2O fluxes under different nitrogen fertilization treatments, but underestimated some large peak fluxes. By pooling all data together, the calibrated APSIM model also performed well in representing cumulative N2O emissions under various treatments at annual and finer （monthly and daily） time scales.
文摘Photocatalytic hydrogen peroxide(H_(2)O_(2))production is a promising strategy to replace the traditional production processes;however,the inefficient H_(2)O_(2) productivity limits its application.In this study,oxygen-rich g-C_(3)N_(4) with abundant nitrogen vacancies(OCN)was synthesized for photocatalytic H_(2)O_(2) production.X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy indicated that oxygen-containing functional groups(–COOH and C–O–C)were obtained.Electron paramagnetic resonance confirmed the successful introduction of nitrogen vacancies.OCN exhibited efficient photocatalytic H_(2)O_(2) production performance of 1965μmol L^(−1) h^(−1) in air under visible-light irradiation.The high H_(2)O_(2) production was attributed to the enhanced adsorption of oxygen,enlarged specific surface area,and promoted carrier separation.An increased H_(2)O_(2) production rate(5781μmol L^(−1) h^(−1))was achieved in a Na_(3)PO_(4) solution.The improved performance was attributed to the changed reactive oxygen species.Specifically,the adsorbed PO_(4)^(3−) on the surface of the OCN promoted the transfer of holes to the catalyst surface.•O_(2)−obtained by O_(2) reduction reacted with adjacent holes to generate 1O_(2),which could efficiently generate H_(2)O_(2) with isopropanol.Additionally,PO_(4)^(3−),as a stabilizer,inhibited the decomposition of H_(2)O_(2).
文摘The measurement of CO2 and N2O effiux from forest soils is of great importance in evaluating the role of forests as sequestering agents of atmospheric CO2 and nitrogen. To quantify the effect of site on temperature dependence of net C-mineralization and N2O-N emissions, three adjacent forest floors under beech, Norway spruce and mixed species stands were investigated at Soiling forest, Germany, by an incubation experiment for three months. The investigated net C-mineralization and N2O-N emissions from all forest floors exhibited an exponential increase with respect to temperature elevation. The temperature coefficient function （Q10 value）, was fitted to flux rates to describe the temperature sensitivity of forest floors on temperature in the range of 1-20℃. Comparing the fitted curves for temperature sensitivity of the forest floors in relation to net carbon mineralization and nitrous oxide emission rates revealed a strong positive correlation across all sites. For the whole data set of all stands, a Q10 value of 1.73-2.10 for net C-mineralization and 2.81-3.58 for N2O-N emissions per measured unit was found to describe the temperature dependency of net C-mineralization and N20-N efflux at experimental site. The absence of clear differences between beech and spruce in mono and mixed species cultures on temperature dependencies of net C-mineralization and N2O-N emission rates indicated that the flux rates were not affected by species-specific differences of litter quality.
文摘Eutrophication and climate change, key environmental concerns, are both linked to the carbon and nitrogen cycles hence the improved understanding of these cycles is essential. Currently, there is no system that simultaneously measures the fluxes of the three key gas phase products of nitrogen and carbon cycling （CO2, CH4 and N2O） in submerged ecosystems with hourly time resolution. A ＂Lake-in-a-box＂ （mesocosm） was developed in the laboratory which allowed the monitoring of key components of the carbon and nitrogen cycles within the air, water and sediments. The approach is automated, simple and time efficient and novel in its ability to examine many different carbon and nitrogen compounds in all three physical component of the ＂lake＂. Dramatic fluctuations in gaseous flux and the concentrations of overlying water and sedimentary carbon and nitrogen compounds were noted over a three week period. These were split into five distinct phases which were linked to changes in sedimentary N and C cycling. The results highlighted the important of links between the two cycles and supported recent studies showing that estuarine sediments can act as both a source and a sink of nitrogen.
基金Supported by National Natural Science Foundation of China(40930530)~~
文摘[Objective] The aim was to study on response of N2O emissions of farm- land ecosystem on temperature rising. [Methed] In farmland ecosystem in Huaibei City in Anhui Province, N2O emission by twelve varieties of crop on temperature was researched with DeNitrification-DeComposition （NDC）. [Result] Response of dry- land crop on temperature rising can be divided into three categories, as follows： The first category, N2O emission of crop changed little during the temperature increasing, for example, from 0 to 3 %;, the emissions by potatoes, cotton, maize and rapeseed increased little and decreased little when temperature changed from 1.5 to 3 ℃. Crops of the second category declined with temperature increasing in N2O emission, for example, N2O emission decreased by 8.1% with temperature increasing from 0 to 3 ℃, including sugar cane, tobacco, wheat, soybean and pea. In third category, N2O emission of crop grew with temperature increasing, for example, the emission of rice, vegetables and fruit trees increased by 22.8% when the temperature grew from 0 to 3 ℃. [Conclusion] The research indicated that N2O emission in ecosystem of drv farmland increased little with temoerature risina.
文摘垃圾填埋场是重要的甲烷释放源,其有效管理是减缓温室效应的重要环节.通过硝化渗滤液回灌模拟垃圾填埋柱,研究硝化渗滤液在新鲜垃圾和老龄垃圾填埋柱中的脱氮及对垃圾稳定化和产甲烷的影响.结果表明,回灌的硝化渗滤液在不同填埋龄垃圾柱中,均可实现总氧化态氮(Total oxidation nitroge,TON)完全还原.当回灌TON负荷分别达到14.19 g t-1(TS)d-1和10.45 g t-1(TS)d-1时,新、老垃圾柱中甲烷产生开始受到抑制.实验后期,回灌TON负荷增至38.78 g t-1(TS)d-1和30.62 g t-1(TS)d-1时,新、老垃圾填埋柱产甲烷相对抑制率分别达54.10%和95.77%.同时,回灌反硝化对新、老垃圾柱中垃圾降解贡献率(Rd)分别达85%和93%,能有效促进垃圾稳定.
文摘Objective To investigate the effect of oral administration of arginine on linear growth of long bones in male pubertal rats and the underlying mechanisms, focusing on expression of genes related to the hypothalamus-pituitary growth axis and the nitric oxide （NO）-cyclic guanosine monophosphate （cGMP） pathway. Methods Rats were randomly divided into control and intervention groups. In the intervention group, arginine was solved in water （0.045 g L-arginine was mixed with 1 mL water） and administered in rats （10 mL/kg） through gastric perfusion once per day, for totally 28 d. Rats in the control group received normal saline treatment. Bone histomorphometry analysis was used to measure growth plate width and mineral apposition rate of the tibia, as well as trabecular bone volume fraction, osteoblast surface and osteo- clast surface of the femur. Serum growth hormone （GH） concentration was determined by radioimmunoassay. Real-time PCR was used to measure the expression of neuronal nitric oxide synthase （nNOS）, soluble guanylyl cyclases （sGCal and sGCfll）, growth hormone-releasing hormone （Ghrh） and somatostatin （SS） in hypothalamus, as well as Gh in pituitary. Western blot was used to detect the protein levels ofnNOS, sGCα1 and sGCβ1 in hypothalamus. Results After treat- ment with arginine, the growth plate width of tibia and osteoblast surface of femur were increased （P 〈 0.05）, and serum GH concentration was elevated （P 〈 0.05）. Besides, mRNA and protein levels ofnNOS and sGCα1 （P 〈 0.05）, as well as the expression of Gh mRNA （P 〈 0.01）, were significantly up-regulated, while the expression of SS mRNA was down- regulated （P 〈 0.05）. Conclusion Oral administration ofarginine could improve linear growth of long bones by regulating mRNA expression of SS and Gh and inducing GH secretion, possibly via nNOS-NO-sGC-cGMP signal transduction pathway.
基金supported by the National Natural Science Foundation of China (Nos.30630058 and 30571725)the Xi'an Municipal Science and Technology Research Project Fund (No.GG06152)the Shanxi Provincial Science and Technology Research and Development Project Fund (No.2007K14-01),China
文摘Objective： To investigate the relationships between endothelial nitric oxide synthases （eNOS） G894T and 27 bpvariable number tandem repeat （VNTR） gene polymorphisms and osteoporosis in the postmenopausal women of Chinese Han nationality. Methods： In the present study, 281 postmenopausal women from Xi＇an urban area in West China were recruited, and divided into osteoporosis, osteopenia, and normal groups according to the diagnostic criteria of osteoporosis proposed by World Health Organization （WHO）. The bone mineral density （BMD） values of lumbar vertebrae and left hips were determined by QDR-2000 dual energy X-ray absorptiometry. Blood samples were tested for plasma biochemical indicators including testosterone, estradiol, calcitonin, osteocalcin, and procollagen type I amino-terminal propeptide by enzyme-linked immunosorbent assay （ELISA）, tartrate-resistant acid phosphatase by spectrophotometric method, and the content of nitric oxide by Griess method. Genome DNA was extracted from whole blood, and G894T polymorphism of eNOS gene was analyzed by using polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） method and 27 bp-VNTR polymorphism of eNOS gene was genotyped by PCR method. Then the relationships between genotypes and biochemical indicators, genotypes and osteoporosis, and haplotypes and osteoporosis were analyzed. Results： The average BMD values of the femoral neck, ward＇s triangle and lumbar vertebrae 1-4 （LI-L4） in the subjects with T/T genotype in eNOS G894T locus were significantly higher than those in the subjects with G/T and G/G genotypes （P〈0.05）. The average BMD of the femoral neck in the subjects with a/a genotype of eNOS 27 bp-VNTR locus was evidently higher than that in the subjects with b/b genotype （P〈0.05）. The plasma testosterone and osteocalcin concentrations in the subjects of eNOS G894T G/T genotype were evidently higher than those in the subjects of other genotypes （P〈0.05）; the plasma estradiol concentration in the subjects of eNOS 27 bp-VNTR a/a genotype was obviously higher than that in the subjects of b/b genotype （P〈0.01）. eNOS G/G homozygous frequencies in osteoporosis women, osteopenia women, and normal women were 85.37%, 76.38%, and 83.87%, respectively （P〉0.05）. 0% osteoporosis woman, 0.79% osteopenia women, and 3.23% normal women were eNOS a/a homozygous （P〈0.05）. The frequencies of eNOS 27 bp-VNTR a allele were 5.33% in the osteoporosis group, 10.24% in the osteopenia group, and 16.13% in the normal group （P〈0.05, odds ratio （OR）=0.29, 95% confidence interval （CI）=0.11-0.77）, suggesting that a/a genotype and a allele might have protective effects on osteoporosis. The haplotype analysis showed that G-b was 87.7% （214/244） in the osteoporosis group （P〈0.05, OR=2.48, 95% CI=1. 18-5.18）. G-a was 5.3% （13/244） in the osteoporosis group （P〈0.05, OR=0.29, 95% CI=0. 11-0.77）. G-b was a risk factor for osteoporosis, and G-a a protective factor. Conclusion： eNOS G894T G/T genotype influenced the plasma testosterone and osteocalcin concentrations, and T/T genotype influenced BMD. eNOS 27 bp-VNTR a/a genotype increased plasma estradiol concentration to have a protective effect on osteoporosis.
