Two novel benzo 15 crown 5 derivatives containing thiocycle(3) and selenacycle(4) have been synthesized in the presence of Na 2S·9H 2O or Na 2Se 2 and characterized by elemental analysis and mass, IR, UV and 1H N...Two novel benzo 15 crown 5 derivatives containing thiocycle(3) and selenacycle(4) have been synthesized in the presence of Na 2S·9H 2O or Na 2Se 2 and characterized by elemental analysis and mass, IR, UV and 1H NMR spectroscopy. The cation binding abilities and selectivities of parent benzo 15 crown 5(1) and its derivatives 3 and 4 with alkali and heavy metal ions have been evaluated by solvent extraction of aqueous metal picrates. The results obtained indicated that novel selera 3 cyclopentene[3,4 d]benzo 15 crown 5(4) showed moderate extractability and selectivity for Ag + over any other alkali and heavy metal ions. [WT5HZ]展开更多
Three novel benzocrown ether derivatives have been synthesized and their cation binding behavior with uni- and bi-valent metal ions was evaluated by the solvent extraction of aqueous metal picrates. The obtained resul...Three novel benzocrown ether derivatives have been synthesized and their cation binding behavior with uni- and bi-valent metal ions was evaluated by the solvent extraction of aqueous metal picrates. The obtained results indicate that the size-fit of crown ether and metal cation, and electron effect of the side arm attached to benzocrown ethers affect their cation binding ability and selectivity.展开更多
Extractability and mobility of Cu and Zn and their relationships with 1) accumulation of Cu and Zn and 2) soil pH were studied in three sandy soils (Wabasso, Ankona, and Winder) from commercial citrus groves in Florid...Extractability and mobility of Cu and Zn and their relationships with 1) accumulation of Cu and Zn and 2) soil pH were studied in three sandy soils (Wabasso, Ankona, and Winder) from commercial citrus groves in Florida, USA. The soils, with a broad range of Cu and Zn concentrations, were fractionated by a modified procedure of Amacher, while Cu and Zn mobility were evaluated using column leaching. The extractability of Cu and Zn increased with decreasing soil pH. Also with increasing total soil Cu and Zn for extractable Cu in the Wabasso sand a threshold level, where the metal extraction rate increased, was noted at 100 mg kg-1, whereas for extractable Zn in the Wabasso sand the threshold level was found at 60 mg kg-1 and in the Ankona sand at 120 mg kg-1. These results suggested that the release potential of Cu and Zn was greater in the Wabasso sand than in the Ankona sand. The column leaching experiment showed that at total soil Cu or Zn concentrations < 100 mg kg-1 all leachates had low Cu and Zn concentrations. However at total concentrations > 200 mg kg-1 for Cu and > 150 mg kg-1 for Zn with decreasing soil pH, the concentrations of both Cu and Zn in the leachates increased exponentially. Also in these sandy soils soluble Cu and Zn mainly originated from the exchangeable fractions, and pH was a key factor controlling Cu and Zn extractability and mobility.展开更多
The famous zero-knowledge succinct non-interactive arguments of knowledge(zk-SNARK) was proposed by Groth in 2016.Typically, the construction is based on quadratic arithmetic programs which are highly efficient concer...The famous zero-knowledge succinct non-interactive arguments of knowledge(zk-SNARK) was proposed by Groth in 2016.Typically, the construction is based on quadratic arithmetic programs which are highly efficient concerning the proof length and the verification complexity. Since then, there has been much progress in designing zk-SNARKs, achieving stronger security,and simulated extractability, which is analogous to non-malleability and has broad applications. In this study, following Groth's pairing-based zk-SNARK, a simulation extractability zk-SNARK under the random oracle model is constructed. Our construction relies on a newly proposed property named target linearly collision-resistant, which is satisfied by random oracles under discrete logarithm assumptions. Compared to the original Groth16 zk-SNARK, in our construction, both parties are allowed to use such a random oracle, aiming to get the same random number. The resulting proof consists of 3 group elements and only 1 pairing equation needs to be verified. Compared to other related works, our construction is shorter in proof length and simpler in verification while preserving simulation extractability. The results also extend to achieve subversion zero-knowledge SNARKs.展开更多
Iron is a limiting factor for the eutrophication of lakes, especially those lakes that are enriched with phosphorus. Extractability of iron in sediments of West Lake and Taihu Lake in China and Lower Lough Erne in Nor...Iron is a limiting factor for the eutrophication of lakes, especially those lakes that are enriched with phosphorus. Extractability of iron in sediments of West Lake and Taihu Lake in China and Lower Lough Erne in Northern Ireland of UK was comparatively investigated on the basis of analysing chemical forms of iron using different extractants. It was shown that extractable iron in sediments of the lakes was greatly different using various extractants. Reactive iron or easily released iron such as “active' iron oxides, total free iron oxide and water-soluble iron was not high, only accounting for 0.01%—0.15% of total iron. The efficiency of the extractants for exchangeable iron was decreased in the sequence 0.1 mol/L HCl DTPA+TEA mixed solution > 1 mol/L NH 4OAc > 0.5 mol/L MgCl 2 = 0.5 mol/L CaCl 2. It seems that the complexion of iron by organic matter was not strong because the concentration of organically bound iron was significantly lower than the concentration it was forecasted. Extractable iron is not entirely consistent with or dependent on total iron in lake sediments. To a certain extent, phosphate can inhibit the release of iron in sediments of the lakes. The selection of extractants is thus the first key step to evaluate bioavailability of iron in lake sediments.展开更多
The impacts of contact time on the extractability, the availability of bexachlorobenzene （HCB） in different soils （paddy soil, red soil, and fluvo-aquic soil） and bioaccumulation in earthworm Eisenia foetida were ...The impacts of contact time on the extractability, the availability of bexachlorobenzene （HCB） in different soils （paddy soil, red soil, and fluvo-aquic soil） and bioaccumulation in earthworm Eisenia foetida were investigated under controlled conditions in laboratory. Results indicated that the aging rate of HCB displaying a biphasic character in different soils： a rapid aging in the first 60 d followed by a slow aging in the next 120 d incubation time. Moreover, most of extractable HCB （about 90%） decline occurred in the first 60 d after HCB was spiked into the soils. The aging rate of HCB in the paddy soil was higher than that in the fluvo-aquic soil or the red soil. The amount of HCB accumulated in the earthworms and its accumulative ability, expressed as a bioaccumulation factor （BAF）, declined as the aging time increased from 1 to 180 d. Although the extractable HCB decreased with increasing residence time in soil, much of HCB could still be accumulated by earthworms （457.6-984.3 ng/g） through bioaccumulation, which poses a potential risk to soil ecological safety.展开更多
文摘Two novel benzo 15 crown 5 derivatives containing thiocycle(3) and selenacycle(4) have been synthesized in the presence of Na 2S·9H 2O or Na 2Se 2 and characterized by elemental analysis and mass, IR, UV and 1H NMR spectroscopy. The cation binding abilities and selectivities of parent benzo 15 crown 5(1) and its derivatives 3 and 4 with alkali and heavy metal ions have been evaluated by solvent extraction of aqueous metal picrates. The results obtained indicated that novel selera 3 cyclopentene[3,4 d]benzo 15 crown 5(4) showed moderate extractability and selectivity for Ag + over any other alkali and heavy metal ions. [WT5HZ]
基金Project supported by the National Natural Science Foundation of China (Nos. 90306009 and 20372038) and Special Fund for Doctoral Program from the Ministry of Education of China (No. 20010055001).
文摘Three novel benzocrown ether derivatives have been synthesized and their cation binding behavior with uni- and bi-valent metal ions was evaluated by the solvent extraction of aqueous metal picrates. The obtained results indicate that the size-fit of crown ether and metal cation, and electron effect of the side arm attached to benzocrown ethers affect their cation binding ability and selectivity.
基金Project partly supported by the U.S. Environmental Protection Agency through a contract with the Nonpoint Source Management/Water Quality Standard Section of the Florida Department of Environmental Protection (No. WM746).
文摘Extractability and mobility of Cu and Zn and their relationships with 1) accumulation of Cu and Zn and 2) soil pH were studied in three sandy soils (Wabasso, Ankona, and Winder) from commercial citrus groves in Florida, USA. The soils, with a broad range of Cu and Zn concentrations, were fractionated by a modified procedure of Amacher, while Cu and Zn mobility were evaluated using column leaching. The extractability of Cu and Zn increased with decreasing soil pH. Also with increasing total soil Cu and Zn for extractable Cu in the Wabasso sand a threshold level, where the metal extraction rate increased, was noted at 100 mg kg-1, whereas for extractable Zn in the Wabasso sand the threshold level was found at 60 mg kg-1 and in the Ankona sand at 120 mg kg-1. These results suggested that the release potential of Cu and Zn was greater in the Wabasso sand than in the Ankona sand. The column leaching experiment showed that at total soil Cu or Zn concentrations < 100 mg kg-1 all leachates had low Cu and Zn concentrations. However at total concentrations > 200 mg kg-1 for Cu and > 150 mg kg-1 for Zn with decreasing soil pH, the concentrations of both Cu and Zn in the leachates increased exponentially. Also in these sandy soils soluble Cu and Zn mainly originated from the exchangeable fractions, and pH was a key factor controlling Cu and Zn extractability and mobility.
基金supported by the National Key R&D Program of China(Grant No.2019YFB2101703)the National Natural Science Foundation of China(Grant Nos.62272107 and U19A2066)+1 种基金the Innovation Action Plan of Shanghai Science and Technology(Grant No.21511102200)the Key R&D Program of Guangdong Province(Grant No.2020B0101090001)。
文摘The famous zero-knowledge succinct non-interactive arguments of knowledge(zk-SNARK) was proposed by Groth in 2016.Typically, the construction is based on quadratic arithmetic programs which are highly efficient concerning the proof length and the verification complexity. Since then, there has been much progress in designing zk-SNARKs, achieving stronger security,and simulated extractability, which is analogous to non-malleability and has broad applications. In this study, following Groth's pairing-based zk-SNARK, a simulation extractability zk-SNARK under the random oracle model is constructed. Our construction relies on a newly proposed property named target linearly collision-resistant, which is satisfied by random oracles under discrete logarithm assumptions. Compared to the original Groth16 zk-SNARK, in our construction, both parties are allowed to use such a random oracle, aiming to get the same random number. The resulting proof consists of 3 group elements and only 1 pairing equation needs to be verified. Compared to other related works, our construction is shorter in proof length and simpler in verification while preserving simulation extractability. The results also extend to achieve subversion zero-knowledge SNARKs.
文摘Iron is a limiting factor for the eutrophication of lakes, especially those lakes that are enriched with phosphorus. Extractability of iron in sediments of West Lake and Taihu Lake in China and Lower Lough Erne in Northern Ireland of UK was comparatively investigated on the basis of analysing chemical forms of iron using different extractants. It was shown that extractable iron in sediments of the lakes was greatly different using various extractants. Reactive iron or easily released iron such as “active' iron oxides, total free iron oxide and water-soluble iron was not high, only accounting for 0.01%—0.15% of total iron. The efficiency of the extractants for exchangeable iron was decreased in the sequence 0.1 mol/L HCl DTPA+TEA mixed solution > 1 mol/L NH 4OAc > 0.5 mol/L MgCl 2 = 0.5 mol/L CaCl 2. It seems that the complexion of iron by organic matter was not strong because the concentration of organically bound iron was significantly lower than the concentration it was forecasted. Extractable iron is not entirely consistent with or dependent on total iron in lake sediments. To a certain extent, phosphate can inhibit the release of iron in sediments of the lakes. The selection of extractants is thus the first key step to evaluate bioavailability of iron in lake sediments.
基金supported by the Open Fund of State Key Laboratory of Soil and Sustainable Agriculture, In- stitute of Soil Science, Chinese Academy of Sciences (No. 0812000037)the Natural Science Research Program of Anhui Education Department of China (No. 2006KJ175B)
文摘The impacts of contact time on the extractability, the availability of bexachlorobenzene （HCB） in different soils （paddy soil, red soil, and fluvo-aquic soil） and bioaccumulation in earthworm Eisenia foetida were investigated under controlled conditions in laboratory. Results indicated that the aging rate of HCB displaying a biphasic character in different soils： a rapid aging in the first 60 d followed by a slow aging in the next 120 d incubation time. Moreover, most of extractable HCB （about 90%） decline occurred in the first 60 d after HCB was spiked into the soils. The aging rate of HCB in the paddy soil was higher than that in the fluvo-aquic soil or the red soil. The amount of HCB accumulated in the earthworms and its accumulative ability, expressed as a bioaccumulation factor （BAF）, declined as the aging time increased from 1 to 180 d. Although the extractable HCB decreased with increasing residence time in soil, much of HCB could still be accumulated by earthworms （457.6-984.3 ng/g） through bioaccumulation, which poses a potential risk to soil ecological safety.
