Five manganese nodules collected from the Northern Mid - Pacific have been analysed for their U and Th isotopes.lt is found that the enrichment of thorium compared to uranium is universal in deep- sea manganese, nodul...Five manganese nodules collected from the Northern Mid - Pacific have been analysed for their U and Th isotopes.lt is found that the enrichment of thorium compared to uranium is universal in deep- sea manganese, nodules and in the top sides of the nodules there are large excesses of Th and Pa decreasing exponentially with depth. For each of the nodules, the concordant growth rates are obtained from three different methods: 230Thex 230Thex/232Th and 231Paex.The growth rates of manganese nodules are closely related to the chemical compositions of the nodules and the types of the underlying sediments. The growth rates of five nodules are determined to be in the range of 0.79-7.4 mm/106a, in agreement with those predicted from the chemical compositions of the nodules. By the comparison of the extrapolated 230Thex,230Thex/232 Th and 231PaeX data from the top and bottom surfaces of the nodule from Site M21 yields, the nodule turnover time is (9.83-13.7)×104a.展开更多
The preparation of specifically iodine-125 (125I)-labeled peptides of high purity and specific activity represents a key tool for the detailed characterization of their binding properties in interaction with their bin...The preparation of specifically iodine-125 (125I)-labeled peptides of high purity and specific activity represents a key tool for the detailed characterization of their binding properties in interaction with their binding partners. Early synthetic methods for the incorporation of iodine faced challenges such as harsh reaction conditions, the use of strong oxidants and low reproducibility. Herein, we review well-established radiolabeling strategies available to incorporate radionuclide into a protein of interest, and our long-term experience with a mild, simple and generally applicable technique of 125I late-stage-labeling of biomolecules using the Pierce iodination reagent for the direct solid-phase oxidation of radioactive iodide. General recommendations, tips, and details of optimized chromatographic conditions to isolate pure, specifically 125I-mono-labeled biomolecules are illustrated on a diverse series of (poly)peptides, ranging up to 7.6 kDa and 67 amino acids (aa). These series include peptides that contain at least one tyrosine or histidine residue, along with those featuring disulfide crosslinking or lipophilic derivatization. This mild and straightforward late-stage-labeling technique is easily applicable to longer and more sensitive proteins, as demonstrated in the cases of the insulin-like growth factor binding protein-3 (IGF-BP-3) (29 kDa and 264 aa) and the acid-labile subunit (ALS) (93 kDa and 578 aa).展开更多
A low-level β counting-or spectrum apparatus used for the detection of the β radiation of thorium-234 and α spectrum of thorium- 228 simultaneously and an easy operating procedure for the enrichment, radiochemical ...A low-level β counting-or spectrum apparatus used for the detection of the β radiation of thorium-234 and α spectrum of thorium- 228 simultaneously and an easy operating procedure for the enrichment, radiochemical separating, sampling and measurement of thorium-234 and uranium-238 in the ocean are developed based on the requirements of analyzing export productivity in the eupho- ric zone via thorium-234 - uranium-238 radioactivity disequilibrium. The detecting efficiency both of 13 and α radiation is higher than 20%. The background of βradiation is less than 0. 5 min ^-1 , and the energy resolution of ct detector is better than 1%. Total recycle ratio of thorium-234 is about 75%. Using the above apparatus and procedure, the radioactivities of dissolved thorium-234 and uranium-238, particle thorium-234 and uranium-238 in seawater of the South China Sea, the Southern Ocean and the Arctic Ocean were analyzed.展开更多
In the past ^68Ge （Germanium-68） was purified with toxic organic solvents in liquid-liquid extractions making the product unacceptable by the FDA （food and drug Administration） for human use. The authors report in...In the past ^68Ge （Germanium-68） was purified with toxic organic solvents in liquid-liquid extractions making the product unacceptable by the FDA （food and drug Administration） for human use. The authors report initial studies utilizing three or four columns consisting of sequences of AG 1, AG50, Chelex 100 and/or Sephadex G25 resins. Five purification methods were examined and a separation consisting of the sequence： AG 1-Chelex100-Sephedex G25 provided 87% recovery of germanium. Fractionation of the elution resulted in high germanium concentrations.展开更多
Obiectives To study the mineralization of 2,4-D in clay and clay loam Egyptian soils under subtropical conditions over a period of 90 d. Methods Using 14C-ring labelled pesticide, laboratory studies under aerobic and ...Obiectives To study the mineralization of 2,4-D in clay and clay loam Egyptian soils under subtropical conditions over a period of 90 d. Methods Using 14C-ring labelled pesticide, laboratory studies under aerobic and anaerobic conditions were conducted. 14C-activity in solutions was directly determined by liquid scintillation counting. Unextractable soil residues were determined by combustion. The nature of methanolic '4C-residues was determined by thin layer and high performance liquid chromatographic analysis. Results Under aerobic conditions 10%-14% of applied dose was mineralized during 90 d irrespective of soil type. The soil extractable pesticide residues decreased with time and the bound residues gradually increased. The highest binding capacity of about 26%-29% was observed in clay soil under aerobic conditions after 90 d. A good balance sheet was obtained and the percentage recovery was generally between 91% and 100%. Conclusion The mineralization of 2,4-D in clay soil was higher than that in clay loam soil under anaerobic conditions. Under aerobic conditions, the soil type had no influence on mineralizaion capacity of 2,4-D during 90 d. The soil binding increased with time whereby the extractable 14C-residues simultaneously decreased. Chromatographic analysis of the methanol extractable l4C-residues of soils revealed the presence of 2,4-D as a main product together with 2,4-dichlorophenol.展开更多
The230Ra has been produced via232Th-2p reaction induced by 60 MeV/u18O ion irradiation of natural thorium. The radium was radiochemically separated from the mixture of thorium and reaction products. Thin Ra sources in...The230Ra has been produced via232Th-2p reaction induced by 60 MeV/u18O ion irradiation of natural thorium. The radium was radiochemically separated from the mixture of thorium and reaction products. Thin Ra sources in which230Ac was got through $^{230} Ra\xrightarrow{{\beta ^ - }}^{230} $ Ac were prepared for observing fission fragments from β-delayed fission of230Ac. The sources were exposed to the mica fission track detectors and measured by the HPGe γ detector. The precursor230Ac was identified by means of observed two fission events as well as γ spectra, and the β-delayed fission probability of230Ac was obtained to be (1.19 ± 0.85) × 10-8.展开更多
Much research effort has been made to understand various biological processes at levels of molecules using molecular imaging techniques. Because of great sensitivity, high resolution, and rapid detection, positron emi...Much research effort has been made to understand various biological processes at levels of molecules using molecular imaging techniques. Because of great sensitivity, high resolution, and rapid detection, positron emission tomography （PET） imaging is becoming one of the most used imaging techniques for medical diagnose and pre-clinical studies. Here we provide a review on molecular imaging and PET imaging. An introduction is also provided on ~SF-fluorine labeling techniques for the preparation of PET imaging probes. A summary and comparison of currently available ~SF-fluorine labeling methods is provided. The per- spectives for 18F-fluorine labeling techniques are also given.展开更多
文摘Five manganese nodules collected from the Northern Mid - Pacific have been analysed for their U and Th isotopes.lt is found that the enrichment of thorium compared to uranium is universal in deep- sea manganese, nodules and in the top sides of the nodules there are large excesses of Th and Pa decreasing exponentially with depth. For each of the nodules, the concordant growth rates are obtained from three different methods: 230Thex 230Thex/232Th and 231Paex.The growth rates of manganese nodules are closely related to the chemical compositions of the nodules and the types of the underlying sediments. The growth rates of five nodules are determined to be in the range of 0.79-7.4 mm/106a, in agreement with those predicted from the chemical compositions of the nodules. By the comparison of the extrapolated 230Thex,230Thex/232 Th and 231PaeX data from the top and bottom surfaces of the nodule from Site M21 yields, the nodule turnover time is (9.83-13.7)×104a.
基金Institutional support was provided by the project of the Czech Academy of Sciences,Czech Republic(to the Institute of Organic Chemistry and Biochemistry)(Project No.:RVO 61388963)This work was supported by the project National Institute for Research of Metabolic and Cardiovascular Diseases(Programme EXCELES)funded by the European Union's Next Generation EU(Project No.:LX22NPO5104)the Czech Science Foundation,Czech Republic(Grant No.:23-05805S).
文摘The preparation of specifically iodine-125 (125I)-labeled peptides of high purity and specific activity represents a key tool for the detailed characterization of their binding properties in interaction with their binding partners. Early synthetic methods for the incorporation of iodine faced challenges such as harsh reaction conditions, the use of strong oxidants and low reproducibility. Herein, we review well-established radiolabeling strategies available to incorporate radionuclide into a protein of interest, and our long-term experience with a mild, simple and generally applicable technique of 125I late-stage-labeling of biomolecules using the Pierce iodination reagent for the direct solid-phase oxidation of radioactive iodide. General recommendations, tips, and details of optimized chromatographic conditions to isolate pure, specifically 125I-mono-labeled biomolecules are illustrated on a diverse series of (poly)peptides, ranging up to 7.6 kDa and 67 amino acids (aa). These series include peptides that contain at least one tyrosine or histidine residue, along with those featuring disulfide crosslinking or lipophilic derivatization. This mild and straightforward late-stage-labeling technique is easily applicable to longer and more sensitive proteins, as demonstrated in the cases of the insulin-like growth factor binding protein-3 (IGF-BP-3) (29 kDa and 264 aa) and the acid-labile subunit (ALS) (93 kDa and 578 aa).
基金This project was supported by the State Social Commonweal Grant(project name:the comprehensive investigation of Nansha Islands waters)the Natural Science Foundation of Fujian Province of China under contract No.2006J0287+2 种基金This study was also supported,in part,by the National Natural Science Foundation of China from key program under contract No.40531007general program under contract Nos 40406014 and 40276001State Social Commonweal Grant under contract No.2004DIB5178.
文摘A low-level β counting-or spectrum apparatus used for the detection of the β radiation of thorium-234 and α spectrum of thorium- 228 simultaneously and an easy operating procedure for the enrichment, radiochemical separating, sampling and measurement of thorium-234 and uranium-238 in the ocean are developed based on the requirements of analyzing export productivity in the eupho- ric zone via thorium-234 - uranium-238 radioactivity disequilibrium. The detecting efficiency both of 13 and α radiation is higher than 20%. The background of βradiation is less than 0. 5 min ^-1 , and the energy resolution of ct detector is better than 1%. Total recycle ratio of thorium-234 is about 75%. Using the above apparatus and procedure, the radioactivities of dissolved thorium-234 and uranium-238, particle thorium-234 and uranium-238 in seawater of the South China Sea, the Southern Ocean and the Arctic Ocean were analyzed.
文摘In the past ^68Ge （Germanium-68） was purified with toxic organic solvents in liquid-liquid extractions making the product unacceptable by the FDA （food and drug Administration） for human use. The authors report initial studies utilizing three or four columns consisting of sequences of AG 1, AG50, Chelex 100 and/or Sephadex G25 resins. Five purification methods were examined and a separation consisting of the sequence： AG 1-Chelex100-Sephedex G25 provided 87% recovery of germanium. Fractionation of the elution resulted in high germanium concentrations.
基金This work was supported by FAO/IAEA-division for its financial support.
文摘Obiectives To study the mineralization of 2,4-D in clay and clay loam Egyptian soils under subtropical conditions over a period of 90 d. Methods Using 14C-ring labelled pesticide, laboratory studies under aerobic and anaerobic conditions were conducted. 14C-activity in solutions was directly determined by liquid scintillation counting. Unextractable soil residues were determined by combustion. The nature of methanolic '4C-residues was determined by thin layer and high performance liquid chromatographic analysis. Results Under aerobic conditions 10%-14% of applied dose was mineralized during 90 d irrespective of soil type. The soil extractable pesticide residues decreased with time and the bound residues gradually increased. The highest binding capacity of about 26%-29% was observed in clay soil under aerobic conditions after 90 d. A good balance sheet was obtained and the percentage recovery was generally between 91% and 100%. Conclusion The mineralization of 2,4-D in clay soil was higher than that in clay loam soil under anaerobic conditions. Under aerobic conditions, the soil type had no influence on mineralizaion capacity of 2,4-D during 90 d. The soil binding increased with time whereby the extractable 14C-residues simultaneously decreased. Chromatographic analysis of the methanol extractable l4C-residues of soils revealed the presence of 2,4-D as a main product together with 2,4-dichlorophenol.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 10075063 & 10175079) Major State Basic Research Development Program and Chinese Academy of Sciences.
文摘The230Ra has been produced via232Th-2p reaction induced by 60 MeV/u18O ion irradiation of natural thorium. The radium was radiochemically separated from the mixture of thorium and reaction products. Thin Ra sources in which230Ac was got through $^{230} Ra\xrightarrow{{\beta ^ - }}^{230} $ Ac were prepared for observing fission fragments from β-delayed fission of230Ac. The sources were exposed to the mica fission track detectors and measured by the HPGe γ detector. The precursor230Ac was identified by means of observed two fission events as well as γ spectra, and the β-delayed fission probability of230Ac was obtained to be (1.19 ± 0.85) × 10-8.
基金supported by the National Natural Science Foundation of China(11304156)the General Financial Grant fromthe China Postdoctoral Science Foundation(2013M531312)
文摘Much research effort has been made to understand various biological processes at levels of molecules using molecular imaging techniques. Because of great sensitivity, high resolution, and rapid detection, positron emission tomography （PET） imaging is becoming one of the most used imaging techniques for medical diagnose and pre-clinical studies. Here we provide a review on molecular imaging and PET imaging. An introduction is also provided on ~SF-fluorine labeling techniques for the preparation of PET imaging probes. A summary and comparison of currently available ~SF-fluorine labeling methods is provided. The per- spectives for 18F-fluorine labeling techniques are also given.
