Phosphorus nutrient characteristics of different maize inbred lines to low-P stress were studied at stages of seedling, steming, earing, silking under pot culture. In the periods of seedling and steming, P uptake effi...Phosphorus nutrient characteristics of different maize inbred lines to low-P stress were studied at stages of seedling, steming, earing, silking under pot culture. In the periods of seedling and steming, P uptake efficiency was the main contributor to P tolerance, and the relative P content in P-tolerant genotypes, 99180 and 99239 were higher than that in sensitive genotype, 99152. At earing stage, P-tolerant genotypes, compared to P-sensitive ones, had higher accumulation of P in upper leaves. When came to the silking stage, P uptake and redistribution efficiency of P-tolerant genotypes were higher than those in 99152. The results also suggested that there are different mechanisms of P nutrient uptake and distribution in different P-tolerant genotypes. Inbred line 99239, according to the investigation, was considered as an efficient stock in the P-uptake while 99180 fallen to the efficient stock of P redistribution.展开更多
The F-rich granites in South China could be distinguished as the high-p subtype andthe low-p subtype according to their P2O5 contents. There are obvious differences in chemicalcomopition of these two subtypes. The hig...The F-rich granites in South China could be distinguished as the high-p subtype andthe low-p subtype according to their P2O5 contents. There are obvious differences in chemicalcomopition of these two subtypes. The high-p subtype is strongly peraluminous and characterized by low silica and very low REE contents, while the low-p subtype is weakly peraluminousand characterized by high silica and very high REE contents. There are also some differences inchemical compositions of feldspars and micas for these two subtypes. The phosphorus of thehigh-p subtype mainly appears to be in the feldspar structure as PAISi-2 substitution or subordinately in amblygonite as an accessory mineral, while the phosphorus of the low-p subtype ismainly in apatite and other phosphate minerals.展开更多
This paper presents the design of an ultra low-voltage (ULV) pseudo operational transconductance amplifier (P-OTA) that is able to operate with a single supply voltage as low as 0.4 V. The proposed circuit is based on...This paper presents the design of an ultra low-voltage (ULV) pseudo operational transconductance amplifier (P-OTA) that is able to operate with a single supply voltage as low as 0.4 V. The proposed circuit is based on the bulk-driven technique and use of cross-coupled self-cascode pairs that boosts the differential DC gain. The stability condition of this structure for the DC gain is considered by definition of two coefficients to cancel out a controllable percentage of the denominator. This expression for stability condition yield optimized value for the DC gain. Also, as the principle of operation of the proposed technique relies on matching conditions, Monte Carlo analyzes are considered to study of the behavior of the proposed circuit against mismatches. The designed P-OTA have a DC gain of 64 dB, 212 KHz unity gain bandwidth, 57phase margin that is loaded by 10 pF differential capacitive loads, while consume only 16 μW. Eventually, from the proposed P-OTA, a low-power Sample and Hold (S/H) circuit with sampling frequency of 10 KS/s has been designed and simulated. The correct functionality for this configuration is verified from –30℃ to 70℃. The simulated data presented is obtained using the HSPICE Environment and is valid for the 90 nm triple-well CMOS process.展开更多
A number of previous papers have studied the problem of recovering low-rank matrices with noise, further combining the noisy and perturbed cases, we propose a nonconvex Schatten p-norm minimization method to deal with...A number of previous papers have studied the problem of recovering low-rank matrices with noise, further combining the noisy and perturbed cases, we propose a nonconvex Schatten p-norm minimization method to deal with the recovery of fully perturbed low-rank matrices. By utilizing the p-null space property (p-NSP) and the p-restricted isometry property (p-RIP) of the matrix, sufficient conditions to ensure that the stable and accurate reconstruction for low-rank matrix in the case of full perturbation are derived, and two upper bound recovery error estimation ns are given. These estimations are characterized by two vital aspects, one involving the best r-approximation error and the other concerning the overall noise. Specifically, this paper obtains two new error upper bounds based on the fact that p-RIP and p-NSP are able to recover accurately and stably low-rank matrix, and to some extent improve the conditions corresponding to RIP.展开更多
Soybean (Glycine max L.) is a very important food and oil crop in China. Legume-rhizobium symbiotic nitrogen (N) fixation is an important biological character and also the base of improving soil fertility of soybean. ...Soybean (Glycine max L.) is a very important food and oil crop in China. Legume-rhizobium symbiotic nitrogen (N) fixation is an important biological character and also the base of improving soil fertility of soybean. However, soybean production and development is severely limited in tropical and subtropical areas in China due to a lack of effective rhizobial inoculants adapting to low-phosphorus (P) acid soils. In the present study, 12 soybean rhizobial strains were isolated and purified from the nodules of two soybean genotypes contrasting in P efficiency, which were grown on different low-P acid soils with different soybean cultivation histories. Results from 16S rDNA sequence analysis showed that these 12 rhizobial strains belonged to the genus of Bradyrhizobium, which had higher nitrogenase activities compared to the control strain, Bradyrhizboium japonicum USDA110. A field experiment was carried out by applying rhizobial inoculants, a mixture of three rhizobial strains that showed the highest ni- trogenase activity, on a typical low-P acid soil in South China. The results showed that, without inocu- lation, no nodules were formed in the three soybean genotypes tested; with inoculation, the nodulation rates in all were 100%. Inoculation with rhizobial inoculants not only made many nodules formed, but also increased soybean shoot biomass and yield, and improved nitrogen (N) and P nutrient status. Among which, shoot dry weight, N and P content of a soybean genotype, Huachun 3, inoculated with rhizobium were increased 154.3%, 152.4% and 163.2% compared to that without inoculation, respec- tively. We concluded that: (i) The effective indigenous rhizobial strains isolated in this study from soybeans on low-P acid soils in South China have the characters of broad host range, high nodulation efficiency, efficient N fixation, great low pH and low P tolerance. (ii) Soil environment and host types are the key factors to screen the effective rhizobial strains. Considering soil pH values and P efficiency of the host genotypes might increase the screening efficiency. (iii) Improving N status and facilitating root growth might be the mechanisms of increasing the P uptake in soybean plants inoculated with the ef- fective rhizobial strains on low-P acid soils. (iv) Inoculation with the effective rhizobial inoculants could significantly improve growth, N and P content of soybean on low-P acid soils, which might be an effec- tive approach to enhance soybean cultivation and development in these areas. Therefore, application and extension of inoculation techniques with effective rhizobial inoculants in legumes would result in great economical, environmental and ecological benefits.展开更多
为了探讨解磷菌肥分区施入对低磷胁迫下马尾松磷营养状况的影响,该文设置了局部和均匀施用解磷菌肥(PSB肥)的盆栽接种试验,并利用WinRHIZO Pro STD1600+根系图像分析软件、H_(2)SO_(4)-H_(2)O_(2)消煮和钼锑抗比色法研究了马尾松不同家...为了探讨解磷菌肥分区施入对低磷胁迫下马尾松磷营养状况的影响,该文设置了局部和均匀施用解磷菌肥(PSB肥)的盆栽接种试验,并利用WinRHIZO Pro STD1600+根系图像分析软件、H_(2)SO_(4)-H_(2)O_(2)消煮和钼锑抗比色法研究了马尾松不同家系根系形态参数和苗木磷素吸收量对PSB肥不同施用方式的响应。结果表明:(1)局部和均匀施用PSB肥均对马尾松生长影响显著,局部施用较均匀显著增加了苗木苗高、地径、根冠比、根系和整株干物质量等主要生长指标。(2)局部施用PSB肥苗木根长、根表面积、根体积和根尖数显著增加,而均匀施用根系各参数有所增加但差异不显著;局部施用较均匀0<根系直径(D)≤0.5 mm的细根根长增加了近2倍。两种处理根系生长的差异与局部施用PSB肥造成了土壤磷素的异质性分布有关。(3)与均匀施用PSB肥相比,局部施用显著增加了苗木根、茎、叶及整株磷素吸收量。相关性分析表明,苗木磷素吸收量与根系形态参数、D≤1.0 mm根系根长呈显著正相关。说明局部施用PSB肥通过诱导根系的生长促进苗木对磷素的吸收。(4)马尾松不同家系对施用PSB肥的响应存在差异。亲本为耐低磷种源的22号家系对局部施用PSB肥较敏感,其各生长指标均显著高于10号和50号家系。综上所述,低磷环境下局部施用PSB肥较均匀施用对马尾松幼苗生长和磷素吸收的影响更加显著,该研究结果可为磷匮乏立地上马尾松人工林的管理提供参考和指导。展开更多
基金This work was supported by the National 863 Program of China(2001AA241051).
文摘Phosphorus nutrient characteristics of different maize inbred lines to low-P stress were studied at stages of seedling, steming, earing, silking under pot culture. In the periods of seedling and steming, P uptake efficiency was the main contributor to P tolerance, and the relative P content in P-tolerant genotypes, 99180 and 99239 were higher than that in sensitive genotype, 99152. At earing stage, P-tolerant genotypes, compared to P-sensitive ones, had higher accumulation of P in upper leaves. When came to the silking stage, P uptake and redistribution efficiency of P-tolerant genotypes were higher than those in 99152. The results also suggested that there are different mechanisms of P nutrient uptake and distribution in different P-tolerant genotypes. Inbred line 99239, according to the investigation, was considered as an efficient stock in the P-uptake while 99180 fallen to the efficient stock of P redistribution.
文摘The F-rich granites in South China could be distinguished as the high-p subtype andthe low-p subtype according to their P2O5 contents. There are obvious differences in chemicalcomopition of these two subtypes. The high-p subtype is strongly peraluminous and characterized by low silica and very low REE contents, while the low-p subtype is weakly peraluminousand characterized by high silica and very high REE contents. There are also some differences inchemical compositions of feldspars and micas for these two subtypes. The phosphorus of thehigh-p subtype mainly appears to be in the feldspar structure as PAISi-2 substitution or subordinately in amblygonite as an accessory mineral, while the phosphorus of the low-p subtype ismainly in apatite and other phosphate minerals.
文摘This paper presents the design of an ultra low-voltage (ULV) pseudo operational transconductance amplifier (P-OTA) that is able to operate with a single supply voltage as low as 0.4 V. The proposed circuit is based on the bulk-driven technique and use of cross-coupled self-cascode pairs that boosts the differential DC gain. The stability condition of this structure for the DC gain is considered by definition of two coefficients to cancel out a controllable percentage of the denominator. This expression for stability condition yield optimized value for the DC gain. Also, as the principle of operation of the proposed technique relies on matching conditions, Monte Carlo analyzes are considered to study of the behavior of the proposed circuit against mismatches. The designed P-OTA have a DC gain of 64 dB, 212 KHz unity gain bandwidth, 57phase margin that is loaded by 10 pF differential capacitive loads, while consume only 16 μW. Eventually, from the proposed P-OTA, a low-power Sample and Hold (S/H) circuit with sampling frequency of 10 KS/s has been designed and simulated. The correct functionality for this configuration is verified from –30℃ to 70℃. The simulated data presented is obtained using the HSPICE Environment and is valid for the 90 nm triple-well CMOS process.
文摘A number of previous papers have studied the problem of recovering low-rank matrices with noise, further combining the noisy and perturbed cases, we propose a nonconvex Schatten p-norm minimization method to deal with the recovery of fully perturbed low-rank matrices. By utilizing the p-null space property (p-NSP) and the p-restricted isometry property (p-RIP) of the matrix, sufficient conditions to ensure that the stable and accurate reconstruction for low-rank matrix in the case of full perturbation are derived, and two upper bound recovery error estimation ns are given. These estimations are characterized by two vital aspects, one involving the best r-approximation error and the other concerning the overall noise. Specifically, this paper obtains two new error upper bounds based on the fact that p-RIP and p-NSP are able to recover accurately and stably low-rank matrix, and to some extent improve the conditions corresponding to RIP.
基金Supported by National Key Basic Research and Development of China (Grant No. 2005CB120902)McKnight Foundation Collaborative Crop Research Program (USA) (Grant No. 05-780)National Natural Science Foundation of China (Grant No. 30571111)
文摘Soybean (Glycine max L.) is a very important food and oil crop in China. Legume-rhizobium symbiotic nitrogen (N) fixation is an important biological character and also the base of improving soil fertility of soybean. However, soybean production and development is severely limited in tropical and subtropical areas in China due to a lack of effective rhizobial inoculants adapting to low-phosphorus (P) acid soils. In the present study, 12 soybean rhizobial strains were isolated and purified from the nodules of two soybean genotypes contrasting in P efficiency, which were grown on different low-P acid soils with different soybean cultivation histories. Results from 16S rDNA sequence analysis showed that these 12 rhizobial strains belonged to the genus of Bradyrhizobium, which had higher nitrogenase activities compared to the control strain, Bradyrhizboium japonicum USDA110. A field experiment was carried out by applying rhizobial inoculants, a mixture of three rhizobial strains that showed the highest ni- trogenase activity, on a typical low-P acid soil in South China. The results showed that, without inocu- lation, no nodules were formed in the three soybean genotypes tested; with inoculation, the nodulation rates in all were 100%. Inoculation with rhizobial inoculants not only made many nodules formed, but also increased soybean shoot biomass and yield, and improved nitrogen (N) and P nutrient status. Among which, shoot dry weight, N and P content of a soybean genotype, Huachun 3, inoculated with rhizobium were increased 154.3%, 152.4% and 163.2% compared to that without inoculation, respec- tively. We concluded that: (i) The effective indigenous rhizobial strains isolated in this study from soybeans on low-P acid soils in South China have the characters of broad host range, high nodulation efficiency, efficient N fixation, great low pH and low P tolerance. (ii) Soil environment and host types are the key factors to screen the effective rhizobial strains. Considering soil pH values and P efficiency of the host genotypes might increase the screening efficiency. (iii) Improving N status and facilitating root growth might be the mechanisms of increasing the P uptake in soybean plants inoculated with the ef- fective rhizobial strains on low-P acid soils. (iv) Inoculation with the effective rhizobial inoculants could significantly improve growth, N and P content of soybean on low-P acid soils, which might be an effec- tive approach to enhance soybean cultivation and development in these areas. Therefore, application and extension of inoculation techniques with effective rhizobial inoculants in legumes would result in great economical, environmental and ecological benefits.
文摘为了探讨解磷菌肥分区施入对低磷胁迫下马尾松磷营养状况的影响,该文设置了局部和均匀施用解磷菌肥(PSB肥)的盆栽接种试验,并利用WinRHIZO Pro STD1600+根系图像分析软件、H_(2)SO_(4)-H_(2)O_(2)消煮和钼锑抗比色法研究了马尾松不同家系根系形态参数和苗木磷素吸收量对PSB肥不同施用方式的响应。结果表明:(1)局部和均匀施用PSB肥均对马尾松生长影响显著,局部施用较均匀显著增加了苗木苗高、地径、根冠比、根系和整株干物质量等主要生长指标。(2)局部施用PSB肥苗木根长、根表面积、根体积和根尖数显著增加,而均匀施用根系各参数有所增加但差异不显著;局部施用较均匀0<根系直径(D)≤0.5 mm的细根根长增加了近2倍。两种处理根系生长的差异与局部施用PSB肥造成了土壤磷素的异质性分布有关。(3)与均匀施用PSB肥相比,局部施用显著增加了苗木根、茎、叶及整株磷素吸收量。相关性分析表明,苗木磷素吸收量与根系形态参数、D≤1.0 mm根系根长呈显著正相关。说明局部施用PSB肥通过诱导根系的生长促进苗木对磷素的吸收。(4)马尾松不同家系对施用PSB肥的响应存在差异。亲本为耐低磷种源的22号家系对局部施用PSB肥较敏感,其各生长指标均显著高于10号和50号家系。综上所述,低磷环境下局部施用PSB肥较均匀施用对马尾松幼苗生长和磷素吸收的影响更加显著,该研究结果可为磷匮乏立地上马尾松人工林的管理提供参考和指导。
