Premature senescence in crop production,especially occurred at the late growth stage,generally results in a reduction in yield and quality.Therefore,it is beneficial for yield and quality to properly delay senescence ...Premature senescence in crop production,especially occurred at the late growth stage,generally results in a reduction in yield and quality.Therefore,it is beneficial for yield and quality to properly delay senescence of plant tissues during the late developmental stage.In this study,it was observed that the chlorophyll content and photosynthetic rate were gradually decreased along leaf growth progression,and the rates of reduction were promoted by drought.Based on gas chromatography-mass spectrometry (GC-MS) analysis,total eight,five,seven,and five kinds of organic compounds that putatively associated with the tissue senescent progression were identified in leaves,fruit branches,petals,and sepals,respectively.It was found that the identified organic compound,such as a-pinene,b-pinene,and pentadecane were present in different tissues.Among the total ten organic substances identified to be related with the leaf senescence,half were specifically detected in the drought treatment.These results suggest some biochemical pathways associated with the leaf senescence are distinctly regulated by drought.The identified organic compounds in the tested tissues showed three types on the performance pattern based on the contents along with the senescent progression,including gradually increasing,decreasing,and a curve with one single peak.Thus,during the senescence process in tissues,a subset of metabolic substances occur modifications on the quantities,reflecting a complicate biochemical reactions are initiated via the senescence signals.Further analysis of the important organic substances will be helpful for elucidation of the tissue senescence mechanism at the biochemical level and provide a new insight of the senescence signaling transductions in cotton.展开更多
Water soluble organic carbon(WSOC) in sediments plays an important role in transference and transformation of aquatic pollutants. This article investigated the inherent mechanisms of how sediemnt grain size affect the...Water soluble organic carbon(WSOC) in sediments plays an important role in transference and transformation of aquatic pollutants. This article investigated the inherent mechanisms of how sediemnt grain size affect the partitioning coeffcient(k) of WSOC. Influences of NaOH extracted humic substances were particularly focused on. Sediments were sampled from two cross-sections of the middle Yellow River and sieved into three size fractions(< 63 μm,63-100 μm,and 100-300 μm) . The total concentration of WSOC in sediments(CWSOC) and k were estimated using multiple water-sediment ratio experiments. Results showed that CWSOC ranged from 0.012 to 0.022 mg/g,while k ranged from 0.8 to 3.9 L/kg. Correlations between the spectrum characteristics of NaOH extracted humic substances and k were analyzed. Strong positive correlations are determined between k and the aromaticity indicators of NaOH extracted humic substances in different sediment size fractions. Comparing with finer fractions(< 63 μm) ,k is higher in larger size fractions(63- 100 μm and 100-300 μm) related to higher aromaticity degree of NaOH extracted humic substances mostly. While negative relationship between k and the area ratio of fourier transform infrared spectroscopy(FT-IR) at 3400 and 1430 cm-1 implied that the lowest k was related to the highest concentration of acidic humic groups in particles < 63 μm. WSOC in finer fractions(< 63 μm) is likely to enter into pore water,which may further accelerate the transportation of aquatic contaminants from sediment to water.展开更多
In this paper, a rational test method for determining biodegradability of organic substanceunder aerobic conditions was established. Index of biodegradation was elaborated through analysis forbiodegradability of organ...In this paper, a rational test method for determining biodegradability of organic substanceunder aerobic conditions was established. Index of biodegradation was elaborated through analysis forbiodegradability of organic substances. 23 organic substance we展开更多
The characteristics of electric charge and molecular weight distribution,oxidation-reduction regimes,e.g.Eh and amounts of organic reducing substances produced by milk vetch during anaerobic decomposition process,were...The characteristics of electric charge and molecular weight distribution,oxidation-reduction regimes,e.g.Eh and amounts of organic reducing substances produced by milk vetch during anaerobic decomposition process,were studied by using electrochemical methods.Interaction between soils and organic reducing substances was also observed.The results indicate that the organic reducing substances were mainly the organic compounds with negative and amphoteric charges,which were distributed in two groups at anodic peak potentials of 0.25 and 0.69 volt in differential pulse voltammograms,respectively.Their apparent molecular weights are all less than 700 daltons,in which those active in oxidation-reducion reaction were distributed in the fraction with apparent molecular weight less than 200 daltons.The organic reduction substances can be oxidized by manganese oxides in their interaction with soils.展开更多
This study is to acquire the relationship between organic substances in water and prevalence of Kashin Beck disease (KBD). We sampled in three endemic areas and their corresponding neighboring non endemic areas, deter...This study is to acquire the relationship between organic substances in water and prevalence of Kashin Beck disease (KBD). We sampled in three endemic areas and their corresponding neighboring non endemic areas, determined the contents of organic substances and examined the children. The results showed that:①humus type B exited only in endemic areas; ②the content of humus type B is proportional to the state of the illness. KBD may be related to the humus type B in drinking water.展开更多
The objective of the present study was to evaluate the physicochemical properties, presence of water and aflatoxin M1, as well as the effect of the time of year (dry or rainy season) to value the quality and safety of...The objective of the present study was to evaluate the physicochemical properties, presence of water and aflatoxin M1, as well as the effect of the time of year (dry or rainy season) to value the quality and safety of conventional and organic raw milk samples. Samples were collected of conventional (n = 12) and organic (n = 11) raw milk from Tizayuca, Hidalgo and from Tuxpan, Veracruz, respectively. Infrared spectrophotometry and other analytical techniques were employed, approved by the International Dairy Federation for the analysis of the physicochemical properties, the cryoscopy technique for the detection of water addition, and high performance liquid chromatography for the determination of aflatoxin M1. Results showed that there are no significant differences in the components of conventional milk in the season of the year, whereas in organic milk a significant difference (P 0.05) was observed in acidity during the seasons of the year (rainy and dry), as well as a decrease in the percentage of lactose in the dry season, with a significant difference (P 0.05). The means of the cryoscopic point of the milk samples complied with the limits established in the Mexican Official Norm (–0.530, –0.560°H) for milk and no effect was found of the time of year on this variable. Of the milk samples, 50% of the conventional milk and 54.55% of organic milk were above the maximum limits permitted for aflatoxin M1, established in Mexico (0.5 μg·Kg-1).展开更多
A new method was proposed for study of organic reducing substances in soils.According to the theoretical relationship between the voltammetric behaviors and reduction-oxidation reaction of reducing substances,the work...A new method was proposed for study of organic reducing substances in soils.According to the theoretical relationship between the voltammetric behaviors and reduction-oxidation reaction of reducing substances,the working conditions of differential pulse voltammetry (d.p.v.)for determining the organic reducing substances produced during the processes of the anaerobic decomposition of plant materials were established with a glass carbon electrode as working electrode,1M Ag-AgCl electrode with large area as reference electrode,0.2M NH4Ac as supporting from -0.5 to +1.2 voltage(vs.M Ag-AgCl).The peak current proportional to the concentration of reducing substances,and the characteristic peak potential of each organic reducing substance were regarded as the quantitative and qualitative base,respectively.These results obtained under the conditions mentioned above directly reflect both the reducing intensity and capacity of the organic reducing system in soils.展开更多
基金supported by the National High Technology R&D Program of China (2008AA10Z113)
文摘Premature senescence in crop production,especially occurred at the late growth stage,generally results in a reduction in yield and quality.Therefore,it is beneficial for yield and quality to properly delay senescence of plant tissues during the late developmental stage.In this study,it was observed that the chlorophyll content and photosynthetic rate were gradually decreased along leaf growth progression,and the rates of reduction were promoted by drought.Based on gas chromatography-mass spectrometry (GC-MS) analysis,total eight,five,seven,and five kinds of organic compounds that putatively associated with the tissue senescent progression were identified in leaves,fruit branches,petals,and sepals,respectively.It was found that the identified organic compound,such as a-pinene,b-pinene,and pentadecane were present in different tissues.Among the total ten organic substances identified to be related with the leaf senescence,half were specifically detected in the drought treatment.These results suggest some biochemical pathways associated with the leaf senescence are distinctly regulated by drought.The identified organic compounds in the tested tissues showed three types on the performance pattern based on the contents along with the senescent progression,including gradually increasing,decreasing,and a curve with one single peak.Thus,during the senescence process in tissues,a subset of metabolic substances occur modifications on the quantities,reflecting a complicate biochemical reactions are initiated via the senescence signals.Further analysis of the important organic substances will be helpful for elucidation of the tissue senescence mechanism at the biochemical level and provide a new insight of the senescence signaling transductions in cotton.
基金supported by the Major State Basic Research Program of China (No. 2007CB407202)the National Natural Science Foundation of China (No. 40501063).
文摘Water soluble organic carbon(WSOC) in sediments plays an important role in transference and transformation of aquatic pollutants. This article investigated the inherent mechanisms of how sediemnt grain size affect the partitioning coeffcient(k) of WSOC. Influences of NaOH extracted humic substances were particularly focused on. Sediments were sampled from two cross-sections of the middle Yellow River and sieved into three size fractions(< 63 μm,63-100 μm,and 100-300 μm) . The total concentration of WSOC in sediments(CWSOC) and k were estimated using multiple water-sediment ratio experiments. Results showed that CWSOC ranged from 0.012 to 0.022 mg/g,while k ranged from 0.8 to 3.9 L/kg. Correlations between the spectrum characteristics of NaOH extracted humic substances and k were analyzed. Strong positive correlations are determined between k and the aromaticity indicators of NaOH extracted humic substances in different sediment size fractions. Comparing with finer fractions(< 63 μm) ,k is higher in larger size fractions(63- 100 μm and 100-300 μm) related to higher aromaticity degree of NaOH extracted humic substances mostly. While negative relationship between k and the area ratio of fourier transform infrared spectroscopy(FT-IR) at 3400 and 1430 cm-1 implied that the lowest k was related to the highest concentration of acidic humic groups in particles < 63 μm. WSOC in finer fractions(< 63 μm) is likely to enter into pore water,which may further accelerate the transportation of aquatic contaminants from sediment to water.
文摘In this paper, a rational test method for determining biodegradability of organic substanceunder aerobic conditions was established. Index of biodegradation was elaborated through analysis forbiodegradability of organic substances. 23 organic substance we
文摘The characteristics of electric charge and molecular weight distribution,oxidation-reduction regimes,e.g.Eh and amounts of organic reducing substances produced by milk vetch during anaerobic decomposition process,were studied by using electrochemical methods.Interaction between soils and organic reducing substances was also observed.The results indicate that the organic reducing substances were mainly the organic compounds with negative and amphoteric charges,which were distributed in two groups at anodic peak potentials of 0.25 and 0.69 volt in differential pulse voltammograms,respectively.Their apparent molecular weights are all less than 700 daltons,in which those active in oxidation-reducion reaction were distributed in the fraction with apparent molecular weight less than 200 daltons.The organic reduction substances can be oxidized by manganese oxides in their interaction with soils.
文摘This study is to acquire the relationship between organic substances in water and prevalence of Kashin Beck disease (KBD). We sampled in three endemic areas and their corresponding neighboring non endemic areas, determined the contents of organic substances and examined the children. The results showed that:①humus type B exited only in endemic areas; ②the content of humus type B is proportional to the state of the illness. KBD may be related to the humus type B in drinking water.
文摘The objective of the present study was to evaluate the physicochemical properties, presence of water and aflatoxin M1, as well as the effect of the time of year (dry or rainy season) to value the quality and safety of conventional and organic raw milk samples. Samples were collected of conventional (n = 12) and organic (n = 11) raw milk from Tizayuca, Hidalgo and from Tuxpan, Veracruz, respectively. Infrared spectrophotometry and other analytical techniques were employed, approved by the International Dairy Federation for the analysis of the physicochemical properties, the cryoscopy technique for the detection of water addition, and high performance liquid chromatography for the determination of aflatoxin M1. Results showed that there are no significant differences in the components of conventional milk in the season of the year, whereas in organic milk a significant difference (P 0.05) was observed in acidity during the seasons of the year (rainy and dry), as well as a decrease in the percentage of lactose in the dry season, with a significant difference (P 0.05). The means of the cryoscopic point of the milk samples complied with the limits established in the Mexican Official Norm (–0.530, –0.560°H) for milk and no effect was found of the time of year on this variable. Of the milk samples, 50% of the conventional milk and 54.55% of organic milk were above the maximum limits permitted for aflatoxin M1, established in Mexico (0.5 μg·Kg-1).
文摘A new method was proposed for study of organic reducing substances in soils.According to the theoretical relationship between the voltammetric behaviors and reduction-oxidation reaction of reducing substances,the working conditions of differential pulse voltammetry (d.p.v.)for determining the organic reducing substances produced during the processes of the anaerobic decomposition of plant materials were established with a glass carbon electrode as working electrode,1M Ag-AgCl electrode with large area as reference electrode,0.2M NH4Ac as supporting from -0.5 to +1.2 voltage(vs.M Ag-AgCl).The peak current proportional to the concentration of reducing substances,and the characteristic peak potential of each organic reducing substance were regarded as the quantitative and qualitative base,respectively.These results obtained under the conditions mentioned above directly reflect both the reducing intensity and capacity of the organic reducing system in soils.
基金Projects(22068021,52064030)supported by the National Natural Science Foundation of ChinaProject(202305AC160064)supported by the Yunnan Young and Middle-aged Academic and Technical Leaders Reserve Talent Program,ChinaProjects(202202AG050011,202202AG050007)supported by Yunnan Major Scientific and Technological Program,China。
