We investigated the potential value of prostate-specific antigen half-life (PSAHL) and decreasing velocity (PSAVd) to predict progression-free survival (PFS) and overall survival (OS) in Chinese patients with ...We investigated the potential value of prostate-specific antigen half-life (PSAHL) and decreasing velocity (PSAVd) to predict progression-free survival (PFS) and overall survival (OS) in Chinese patients with prostate cancer. A total of 153 patients treated with hormonal therapy were included in the study. Of these, 78 patients progressed to hormone- refractory prostate cancer (HRPC) and 24 patients died by the end of follow-up. PSAHL was defined as the time during which prostate-specific antigen (PSA) concentration became half of the initial value during the first hormonal therapy. PSAVd reflected the decreasing velocity of PSA during the first hormonal therapy. PFS was defined as the interval from the beginning of hormonal therapy to HRPC. Cox proportional hazards regression analysis was used to evaluate whether PSAHL and PSAVd were significantly associated with PFS and OS. The median PSAHL and PSAVd were 0.50 months and 33.8 ng mL^-1 per month. The median PFS and OS were 22.7 months (95% confidence interval [CI], 22.0-29.6 months) and 43.5 months (95% CI, 37.9-48.4 months), respectively. On univariate and multivariate analysis, long PSAHL (〉 0.5 months), metastatic disease, high biopsy Gleason scores (〉 8) and high nadir PSA (〉 0.4 ng mL^-1) were all found to be significantly associated with short PFS. Long PSAHL, high nadir PSA and short PSA doubling time (PSADT 〈 2.0 months) were significantly associated with short OS. There were no significant relationships between PSAVd and either PFS or OS. Thus, PSAHL is a promising new independent predictor of survival. Patients with long PSAHL were identified as those at high risk for a relatively short PFS and OS.展开更多
Based on the newest experimentally extracted nuclear density distributions for double-magic nucleus208Pb(Tarbert et al. in Phys Rev Lett 112:242502, 2014),the sensitivity of α-decay half-life to nuclear skin thicknes...Based on the newest experimentally extracted nuclear density distributions for double-magic nucleus208Pb(Tarbert et al. in Phys Rev Lett 112:242502, 2014),the sensitivity of α-decay half-life to nuclear skin thickness is explored in the vicinity of the shell closure region around208 Pb, i.e., isotopes of Z ? 82 and isotones of N ? 126.With the two-parameter Fermi(2PF) density distributions and an analytically derived formula, the α-decay half-life is found to be closely related to the magnitude of nuclear skin thickness. For a decays to the Z ? 82 isotopes, the α-decay half-life is found to decrease with the increasing neutron skin thickness, while the opposite behavior is found for a decays to the N ? 126 isotones. Therefore, it could be a possible way to extract the nuclear skin thickness from measured α-decay half-lives.展开更多
Antibodies are currently the fastest growing class of therapeutic proteins. When antibody fragments are included, there are over thirty-five antibody-based medicines approved for human therapy. Many more antibody and ...Antibodies are currently the fastest growing class of therapeutic proteins. When antibody fragments are included, there are over thirty-five antibody-based medicines approved for human therapy. Many more antibody and antibody-like fragments are being evaluated clinically. Production of antibody fragments can be efficient and their compact size can allows for better tissue extravasation into solid tumors than full antibodies. Unfortunately, a key limitation of antibody fragments for systemic use is their short half-life in circulation. Prolonging their circulation half-life can be accomplished clinically by the covalent conjugation of the antibody fragment to the water-soluble polymer, poly(ethylene glycol) (PEG). Many polymers and strategies are also being pursued to increase antibody fragment half-life.展开更多
The accelerator mass spectrometry(AMS) is an effective method for the determination of the half-life of long-lived radionuclides. In this paper, we report a method for measurement of the half-life of ^79Se. The numb...The accelerator mass spectrometry(AMS) is an effective method for the determination of the half-life of long-lived radionuclides. In this paper, we report a method for measurement of the half-life of ^79Se. The number of ^79Se atoms was determined from measured ^79Se/Se absolute ratios with the AMS system at the China Institute of Atomic Energy and the decay rate of ^79Se was determined by counting the emitted β-rays with a liquid scintillation spectrometer. The major improvements of our measurements include using the high abundance of an ^79Se sample which was cooled for many years to exclude the interference of short-lived nuclides, the extraction of SeO-2molecular ions, that results in a suppression of the ^79Br background by as much as about five orders of magnitude. Also, an AMS measurement of the absolute ratio of ^79Se/Se was developed to avoid systematic errors. The results show that ^79Se/Se is(2.35±0.12)×10^-7in the reference sample and the radioactivity of ^79Se is(1.24±0.05) Bq/g, so the half-life of ^79Se is(2.78±0.18)×10^5a.展开更多
A three-dimensional model was established to investigate water exchange in coastal waters, and applied to Qinzhou Bay(QZB) in the South China Sea. Given the strong tidal current in QZB, a half-life time was calculated...A three-dimensional model was established to investigate water exchange in coastal waters, and applied to Qinzhou Bay(QZB) in the South China Sea. Given the strong tidal current in QZB, a half-life time was calculated for water exchange by filtering the tidal signal from the concentrations of a conservative substance. In a control run driven by the tide, without external inputs and an open boundary concentration of zero, it was estimated that the average half-life time in QZB was 54.8 d. Numerical experiments showed that wind accounted for an 11.9% reduction in the half-life time to 48.3 d. When rivers were included in the model, the half-life time decreased by 74.6% to 13.9 d. Sensitivity experiments showed that the half-life time for water exchange was greatly affected by the concentration of the conservative substance which was used at the open boundary. In response to 10,20, 30, and 40% increases in the boundary concentration, the half-life time increased to 91.5, 168.3, 186.2, and 229.1 d,respectively. Results also suggested that for coastal bays with large intertidal areas such as QZB, consideration of the wet and dry processes produced more accurate simulations of the hydrodynamics and the half-life times. Simulations, which did not incorporate wet and dry processes, were more than likely to have overestimated or underestimated the half-life times for water exchange.展开更多
The neutrons have been captured by Erbium nuclei which were received by using clinical electron linear accelerator. In this experiment, the possibility of the neutron capture process has been observed because of emitt...The neutrons have been captured by Erbium nuclei which were received by using clinical electron linear accelerator. In this experiment, the possibility of the neutron capture process has been observed because of emitted neutrons appearing in the experimental area. In particular,neutron capture of ^(170)Er nucleus has been observed. After the neutron capture of ^(170)Er nucleus, the unstable ^(171)Er has been formed and decayed into the ^(171)Tm. By using this reaction path, some transition energies of ^(171)Tm obtained from the residual activity measurements and the half-life of ^(171)Er have been determined, and they are in agreement with adopted values in the literature.展开更多
Purpose Due to the few reports on the^(91)Sr half-life previously,the accuracy and uncertainty of the results are difficult to meet the requirements such as calculating the cross section and thefission yields of 235U,23...Purpose Due to the few reports on the^(91)Sr half-life previously,the accuracy and uncertainty of the results are difficult to meet the requirements such as calculating the cross section and thefission yields of 235U,238U,and 239Pu.To solve the discrepancy of^(91)Sr half-life in existing experimental data,the half-life of^(91)Sr was measured in this work,and the uncertainty was discussed in detail.Method The measurements were performed by the activation method implemented for the uranium sample using the K-400 neutron generator at the Chinese Academy of Engineering Physics(CAEP).The half-life of^(91)Sr was measured byγ-ray spectrometry using the high-resolution High Purity Germanium(HPGe)Detector.Results Through exponential functionfitting and a detailed discussion of the uncertainty evaluation,the half-life of^(91)Sr in the present work was determined to be 9.65±0.30 h,which was consistent with the values reported previously and the uncertainty was reduced greatly,however,the uncertainty assessment of the latter was barely documented.Conclusions In this work,a more accurate measurement of the^(91)Sr half-life is provided,as well as the uncertainty is discussed in detail.This result will provide essential information for applications using an activation method,such as the calculation offission yields of 235U,238U,and 239Pu.展开更多
The isomeric ratio of^(184m,g)Re and the half-life of^(184g)Re were measured in the ^(185)Re(n,2n)^(184)Re reaction at 14.8 MeV,and the uncertainty was discussed in detail.The measurements were performed using the act...The isomeric ratio of^(184m,g)Re and the half-life of^(184g)Re were measured in the ^(185)Re(n,2n)^(184)Re reaction at 14.8 MeV,and the uncertainty was discussed in detail.The measurements were performed using the activation method implemented for a rhenium sample using the K-400 neutron generator at the Chinese Academy of Engineering Physics(CAEP).Isomeric state and ground state nuclei of ^(184)Re were identified by their γ-ray spectra.To eliminate the effect of the γ-ray emitted from the isomer on the counting of the ground state characteristic peaks,the isomeric ratio of^(184m,g)Re was calculated to be 0.29±0.11 according to the neutron activation cross-section formula.This result is consistent with previous data within the uncertainty and can be used to determine parameters that characterize the dependence of the level density on the excitation energy and angular momentum.Through exponential function fitting and a detailed discussion of the uncertainty evaluation,the half-life of^(184g)Re was determined as 35.43±0.16 d,which is consistent with the currently recommended value;however,the uncertainty assessment of the latter was barely documented.In addition,this study indicates that the half-life of the ground state can be obtained by eliminating the contamination of γ-rays emitted from the isomer,which provides the possibility of determining the half-lives of nuclides containing isomers.展开更多
BACKGROUND Glucagon-like peptide-1(GLP1)is an endogenous peptide that regulates blood glucose level.But its susceptibility to rapid metabolic degradation limits its therapeutic use.AIM To prepare GLP1-encapsulated nan...BACKGROUND Glucagon-like peptide-1(GLP1)is an endogenous peptide that regulates blood glucose level.But its susceptibility to rapid metabolic degradation limits its therapeutic use.AIM To prepare GLP1-encapsulated nanosize particle with controlled release property to improve the systemic half-life of GLP1.METHODS GLP1 nanoparticles were prepared by complexation of GLP1 with carbonate apatite nanoparticles(CA NPs).The physicochemical properties of the CA NPs,the effects of GLP1-loaded CA NPs on cell viability,and the systemic bioavailability of GLP1 after CA NPs administration were determined.RESULTS The GLP1-loaded CA NPs was within 200 nm in size and stable in fetal bovine serum.The formulation did not affect the viability of human cell lines suggesting that the accumulation of CA NPs in target tissues is safe.In Sprague Dawley rats,the plasma GLP1 Levels as measured from the GLP1-loaded CA NPs-treated rats,were significantly higher than that of the control rats and free GLP1-treated rats at 1 h post-treatment(P<0.05),and the level remained higher than the other two groups for at least 4 h.CONCLUSION The GLP1-loaded CA NPs improved the plasma half-life of GLP1.The systemic bioavailability of GLP1 is longer than other GLP1 nanoparticles reported to date.展开更多
A radioactive nucleus is characterized with an intrinsic half-life. However, for a nuclear species, the half-lives inneutral atoms could be very different from that in highly charged ions. The half-lives of some highl...A radioactive nucleus is characterized with an intrinsic half-life. However, for a nuclear species, the half-lives inneutral atoms could be very different from that in highly charged ions. The half-lives of some highly charged ionshave been directly measured at GSI for multiple motivations[1]. In the same case, the nuclear state(i:e the isomer)may be in the range of several tens of microseconds and their half-live can be measured using isochronous massspectrometry. The J = 8+ isomeric state in 94Ru was chosen to test this method. The half-life of this isomer is71 s [2] in neutral atoms, and the excitation energy is 2.64 MeV. The internal conversion coefficient of this decayin neutral atom is 0.335. So its half-life in the bare nucleus would be modified to be 94.78 s when the internalconversion channel is blocked.展开更多
Protein-based therapeutics (PPTs) are drugs used to treat a variety of different conditions in the human body by alleviating enzymatic deficiencies, augmenting other proteins and drugs, modulating signal pathways, and...Protein-based therapeutics (PPTs) are drugs used to treat a variety of different conditions in the human body by alleviating enzymatic deficiencies, augmenting other proteins and drugs, modulating signal pathways, and more. However, many PPTs struggle from a short half-life due to degradation caused by irreversible protein aggregation in the bloodstream. Currently, the most researched strategies for improving the efficiency and longevity of PPTs are post-translational modifications (PTMs). The goal of our research was to determine which type of PTM increases longevity the most for each of three commonly-used therapeutic proteins by comparing the docking scores (DS) and binding free energies (BFE) from protein aggregation and reception simulations. DS and BFE values were used to create a quantitative index that outputs a relative number from −1 to 1 to show reduced performance, no change, or increased performance. Results showed that methylation was the most beneficial for insulin (p < 0.1) and human growth hormone (p < 0.0001), and both phosphorylation and methylation were somewhat optimal for erythropoietin (p < 0.1 and p < 0.0001, respectively). Acetylation consistently provided the worst benefits with the most negative indices, while methylation had the most positive indices throughout. However, PTM efficacy varied between PPTs, supporting previous studies regarding how each PTM can confer different benefits based on the unique structures of recipient proteins.展开更多
Water exchange is an important hydrodynamic character of sea bays, and it is the basis for the study of the environmental capacity of sea bays. In this paper, a relation matrix is set up to describe the interaction am...Water exchange is an important hydrodynamic character of sea bays, and it is the basis for the study of the environmental capacity of sea bays. In this paper, a relation matrix is set up to describe the interaction among different areas of a sea bay, and to predict the water quality of those areas. The relation matrix is calculated based on the numerical results from a water quality model. This method is applied to the study of water exchange and the prediction of water quality of the Bohai Sea. The Bohai Sea is divided into five areas, and the effect of seasonal wind is taken into consideration. The results show a) the relation matrix can be used to study the water exchange among different areas and predict water quality of different areas at the respective characteristic time, b) the reduction of pollutant is dependent on both water exchange and initial distribution of the pollutant, and c) the half-life time of the pollutant is longer than the half-exchange time of the sea water.展开更多
3D-QSAR studies of persistent organic pollutants(POPs)screening for atmosphere persistence were performed by comparative molecular field analysis(CoMFA)and comparative molecular similarity index analysis(CoMSIA)method...3D-QSAR studies of persistent organic pollutants(POPs)screening for atmosphere persistence were performed by comparative molecular field analysis(CoMFA)and comparative molecular similarity index analysis(CoMSIA)methods.The mean and maximum half-life estimations for degradation in air of 49 UNEP POPs and possible POPs were modeled.Both groups’data have been modeled to obtain an average estimate and a predictive value for ranking and screening purposes.CoMFA and CoMSIA models have given cross-validation regre...展开更多
A greenhouse experiment was conducted to investigate the effect of surface film-forming material (SFFM), a mixture of 16-18-octadecanols by emulsification, on water evaporation. Air-dried soil with distilled water was...A greenhouse experiment was conducted to investigate the effect of surface film-forming material (SFFM), a mixture of 16-18-octadecanols by emulsification, on water evaporation. Air-dried soil with distilled water was incubated firstly for 7 days to reestablish soil biological activity and then for another 7 days after treated with SFFM at rates of 0, 1, 2, 4, 6 and 8 g m-2, respectively. Everyday during the 7-day incubation after addition of SFFM, water losses due to evaporation were ~measured by an electronic balance. The rate of water evaporation with the addition of SFFM was reduced significantly compared with the control treatment and the effectiveness of SFFM on water evaporation reduced with time. According to the equation expressions of the effect of SFFM on water evaporation, the half-life of electiveness of SFFM on water evaporation was introduced and calculated to analyze quantitative relationship between the effectiveness of SFFM on water evaporation and the addition rate of SFFM. The calculated half-life increased with the addition rate of SFFM and the confidence of the calculated values of the half-life was high, suggesting that the half-life of effectiveness of SFFM on water evaporation could be described quantitatively and may be helpful for ameliorating application method of SFFM and screening surface-film forming materials in order to improve nitrogen fertilizer use efficiency in flooded rice fields.展开更多
A field experiment was employed to study the degradation of triadimefon and difenoconazole residues in strawberry and soil. The results showed that the degradation of both the two kinds of pesticides was in accordance...A field experiment was employed to study the degradation of triadimefon and difenoconazole residues in strawberry and soil. The results showed that the degradation of both the two kinds of pesticides was in accordance with the first order kinetic equation. The half-lives of difenoconazole in strawberry fruit, strawberry stem leaf and soil were 4.09, 8.21 and 13.38 d, respectively; and the half-lives of triadimefon in strawberry fruit, strawberry stem and leaf and soil were 3.38, 5.31 and 15.64 d, respectively. The maximum residue limit (MRL) of difenoconazole in strawberry was recommended as 0.5 mg/kg, and 10% difenoconazole WG and 20% triadimefon EC should be applied four times with a safety interval of 7 d according to the amounts of 100 and 60 g a. i./hm2,respectively.展开更多
Four kinds of plant materials (astragalus, azolla, rice straw and water hyacinth) were allowed to decompose for 10 years in two soils with different mineralogical characteristics in fields under upland and submerged c...Four kinds of plant materials (astragalus, azolla, rice straw and water hyacinth) were allowed to decompose for 10 years in two soils with different mineralogical characteristics in fields under upland and submerged conditions. Greater amounts of C and N from azolla were retained in soils throughout the 10-year experimental period compared to those from the other plant materials. The residual C Of all the plant materials in the two soils under upland conditions mineralized st rates corresponding to half-lives between 4.4-6.6 years,while the corresponding figures for thine under submerged conditions were between 6.5-13.1 years. Minerallization of residual organic N followed the same pattern as residual C. Compared to residual C, however, the mineralization rates of residual organic N in most cases were significantly lower and the percentages of added N regained in sons were higher. More N from plat materials was retained in the yellow-brown soil than in the red soil, but no consistent differences in the amounts of C from plant materials and in the mineralization rates of both residual C and residual organic N between the two soils could be found.展开更多
The soils, tropical climate, and network of canals and rivers of southern Vietnam have created one of the most diverse tropical jungles and intensely cultivated landscapes of Southeast Asia. This paradise has a long h...The soils, tropical climate, and network of canals and rivers of southern Vietnam have created one of the most diverse tropical jungles and intensely cultivated landscapes of Southeast Asia. This paradise has a long history of numerous wars, foreign occupations, and most recently the Second Indochina War (aka the Vietnam War 1965-1972) which defoliated rain forests and ancient wetland mangroves and left behind contaminated soil and sediment hotspots. During this war, the United States (US) military sprayed 80 million liters of Agent Orange contaminated with the dioxin TCDD in a guerrilla war against communist insurgents. Agent Orange was a synthetic plant growth regulator comprised of equal amounts of two herbicides 2,4-dichloro phenoxyacetic acid C8H6Cl2O3 (2,4-D) and 2,4,5-trichlorophenoxyacetic acid C8H5Cl3O3 (2,4,5-T). TCDD, the dioxin, 2,3,7,8-tetrachlorodibenzodioxin (C12H4Cl4O2) was an unintended byproduct of the accelerated combustion process used in the manufacture of herbicides containing 2,4,5-T. Agent Orange has frequently been blamed for soil and sediment contamination and long-term human health problems;however, the true source of harm is the dioxin TCDD. Agent Orange has a short half-life of days and weeks after application to vegetation, and has not been found to persist, after 50 years, in the water or soils of southern Vietnam. However, the half-life of dioxin TCDD depends on where it is deposited and varies from 1 to 3 years on soil surfaces that have been fully exposed to sunlight, to as long as 20 to 50 years or more when buried in tropical subsoils, and more than 100 years in river and sea sediments. Dioxin TCDD was heavily concentrated in the US Air Force bases in Vietnam where the herbicides were stored, loaded on planes and helicopters for aerial spraying, and used extensively around military base perimeter fences as a security measure to prevent surprise attacks. Bien Hoa Air Force base, 40 km northeast of Ho Chi Minh City, continues to be one of the mega-hotspots where after 48 years the dioxin TCDD levels in fish and shrimp are still high and fishing is banned in ponds and lakes adjacent to the airbase. Although expensive, one of the most effective remediation to dioxin TCDD contaminated soils is incineration which is the recommended method of dioxin TCDD disposal.展开更多
The binding of recombinant human macrophage colony-stimulating factor (M-CSF) soluble receptor (rh-M-CSF-sR) to membrane-bound macrophage colony stimulating factor (m-M-CSF) and the internalization and recycling of rh...The binding of recombinant human macrophage colony-stimulating factor (M-CSF) soluble receptor (rh-M-CSF-sR) to membrane-bound macrophage colony stimulating factor (m-M-CSF) and the internalization and recycling of rh-M-CSF-sR/m-M-CSF complexes mediated by m-M-CSF were studied with a model of J6-1 cell line. The results indicated that m-M-CSF bound rh-M-CSF-sR with high affinity (Kd= 1.78×10 12 mol/L) and mediated a temperature- and energy-dependent internalization of rh-M-CSF-sR, and that internalized rh-M-CSF-sR could return to the cell surface in an m-M-CSF-bound state, suggesting that m-M-CSF may have a capability to mediate the internalization and recycling of rh-M-CSF-sR/m-M-CSF complexes. In addition, the half-lives of cell-associated M-CSF and its receptor of stimulated normal human cord blood mononuclear cells (CBMCs) and 4 leukemic cell lines were measured by indirect immunoflu-orescence and flow cytometry. The results showed that the half-lives of the various kinds of M-CSF isoforms and展开更多
文摘We investigated the potential value of prostate-specific antigen half-life (PSAHL) and decreasing velocity (PSAVd) to predict progression-free survival (PFS) and overall survival (OS) in Chinese patients with prostate cancer. A total of 153 patients treated with hormonal therapy were included in the study. Of these, 78 patients progressed to hormone- refractory prostate cancer (HRPC) and 24 patients died by the end of follow-up. PSAHL was defined as the time during which prostate-specific antigen (PSA) concentration became half of the initial value during the first hormonal therapy. PSAVd reflected the decreasing velocity of PSA during the first hormonal therapy. PFS was defined as the interval from the beginning of hormonal therapy to HRPC. Cox proportional hazards regression analysis was used to evaluate whether PSAHL and PSAVd were significantly associated with PFS and OS. The median PSAHL and PSAVd were 0.50 months and 33.8 ng mL^-1 per month. The median PFS and OS were 22.7 months (95% confidence interval [CI], 22.0-29.6 months) and 43.5 months (95% CI, 37.9-48.4 months), respectively. On univariate and multivariate analysis, long PSAHL (〉 0.5 months), metastatic disease, high biopsy Gleason scores (〉 8) and high nadir PSA (〉 0.4 ng mL^-1) were all found to be significantly associated with short PFS. Long PSAHL, high nadir PSA and short PSA doubling time (PSADT 〈 2.0 months) were significantly associated with short OS. There were no significant relationships between PSAVd and either PFS or OS. Thus, PSAHL is a promising new independent predictor of survival. Patients with long PSAHL were identified as those at high risk for a relatively short PFS and OS.
基金supported by the National Natural Science Foundation of China(Nos.11175085,11235001,11375086,and 11120101005)the 973 Program of China(No.2013CB834400)+1 种基金the Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the Open Project Program of the State Key Laboratory of Theoretical Physics,Institute of Theoretical Physics,Chinese Academy of Sciences,China(No.Y5KF141CJ1)
文摘Based on the newest experimentally extracted nuclear density distributions for double-magic nucleus208Pb(Tarbert et al. in Phys Rev Lett 112:242502, 2014),the sensitivity of α-decay half-life to nuclear skin thickness is explored in the vicinity of the shell closure region around208 Pb, i.e., isotopes of Z ? 82 and isotones of N ? 126.With the two-parameter Fermi(2PF) density distributions and an analytically derived formula, the α-decay half-life is found to be closely related to the magnitude of nuclear skin thickness. For a decays to the Z ? 82 isotopes, the α-decay half-life is found to decrease with the increasing neutron skin thickness, while the opposite behavior is found for a decays to the N ? 126 isotones. Therefore, it could be a possible way to extract the nuclear skin thickness from measured α-decay half-lives.
文摘Antibodies are currently the fastest growing class of therapeutic proteins. When antibody fragments are included, there are over thirty-five antibody-based medicines approved for human therapy. Many more antibody and antibody-like fragments are being evaluated clinically. Production of antibody fragments can be efficient and their compact size can allows for better tissue extravasation into solid tumors than full antibodies. Unfortunately, a key limitation of antibody fragments for systemic use is their short half-life in circulation. Prolonging their circulation half-life can be accomplished clinically by the covalent conjugation of the antibody fragment to the water-soluble polymer, poly(ethylene glycol) (PEG). Many polymers and strategies are also being pursued to increase antibody fragment half-life.
基金Supported by National Natural Science Foundation of China(11175266)
文摘The accelerator mass spectrometry(AMS) is an effective method for the determination of the half-life of long-lived radionuclides. In this paper, we report a method for measurement of the half-life of ^79Se. The number of ^79Se atoms was determined from measured ^79Se/Se absolute ratios with the AMS system at the China Institute of Atomic Energy and the decay rate of ^79Se was determined by counting the emitted β-rays with a liquid scintillation spectrometer. The major improvements of our measurements include using the high abundance of an ^79Se sample which was cooled for many years to exclude the interference of short-lived nuclides, the extraction of SeO-2molecular ions, that results in a suppression of the ^79Br background by as much as about five orders of magnitude. Also, an AMS measurement of the absolute ratio of ^79Se/Se was developed to avoid systematic errors. The results show that ^79Se/Se is(2.35±0.12)×10^-7in the reference sample and the radioactivity of ^79Se is(1.24±0.05) Bq/g, so the half-life of ^79Se is(2.78±0.18)×10^5a.
基金supported by the NSFC-Shandong Joint Fund for Marine Science Research Centers(Grant No.U1406404)the Fundamental Research Funds for National Public Research Institutes of China(Grant No.2014T01)+2 种基金the National Program on Global Change and Air-Sea Interaction(Grant No. GASI-03-IPOVAI-05)supported by the AoShan Talents Programthe Qingdao National Laboratory for Marine Science and Technology(Grant No. 2015ASTP)
文摘A three-dimensional model was established to investigate water exchange in coastal waters, and applied to Qinzhou Bay(QZB) in the South China Sea. Given the strong tidal current in QZB, a half-life time was calculated for water exchange by filtering the tidal signal from the concentrations of a conservative substance. In a control run driven by the tide, without external inputs and an open boundary concentration of zero, it was estimated that the average half-life time in QZB was 54.8 d. Numerical experiments showed that wind accounted for an 11.9% reduction in the half-life time to 48.3 d. When rivers were included in the model, the half-life time decreased by 74.6% to 13.9 d. Sensitivity experiments showed that the half-life time for water exchange was greatly affected by the concentration of the conservative substance which was used at the open boundary. In response to 10,20, 30, and 40% increases in the boundary concentration, the half-life time increased to 91.5, 168.3, 186.2, and 229.1 d,respectively. Results also suggested that for coastal bays with large intertidal areas such as QZB, consideration of the wet and dry processes produced more accurate simulations of the hydrodynamics and the half-life times. Simulations, which did not incorporate wet and dry processes, were more than likely to have overestimated or underestimated the half-life times for water exchange.
基金supported by the Sinop University Scientific Research Projects Coordination Unit.Project Number:FEF-1901-14-04,2014
文摘The neutrons have been captured by Erbium nuclei which were received by using clinical electron linear accelerator. In this experiment, the possibility of the neutron capture process has been observed because of emitted neutrons appearing in the experimental area. In particular,neutron capture of ^(170)Er nucleus has been observed. After the neutron capture of ^(170)Er nucleus, the unstable ^(171)Er has been formed and decayed into the ^(171)Tm. By using this reaction path, some transition energies of ^(171)Tm obtained from the residual activity measurements and the half-life of ^(171)Er have been determined, and they are in agreement with adopted values in the literature.
基金supported by the National Natural Science Foundation of China(Grant No.11975113).
文摘Purpose Due to the few reports on the^(91)Sr half-life previously,the accuracy and uncertainty of the results are difficult to meet the requirements such as calculating the cross section and thefission yields of 235U,238U,and 239Pu.To solve the discrepancy of^(91)Sr half-life in existing experimental data,the half-life of^(91)Sr was measured in this work,and the uncertainty was discussed in detail.Method The measurements were performed by the activation method implemented for the uranium sample using the K-400 neutron generator at the Chinese Academy of Engineering Physics(CAEP).The half-life of^(91)Sr was measured byγ-ray spectrometry using the high-resolution High Purity Germanium(HPGe)Detector.Results Through exponential functionfitting and a detailed discussion of the uncertainty evaluation,the half-life of^(91)Sr in the present work was determined to be 9.65±0.30 h,which was consistent with the values reported previously and the uncertainty was reduced greatly,however,the uncertainty assessment of the latter was barely documented.Conclusions In this work,a more accurate measurement of the^(91)Sr half-life is provided,as well as the uncertainty is discussed in detail.This result will provide essential information for applications using an activation method,such as the calculation offission yields of 235U,238U,and 239Pu.
基金Supported by the National Natural Science Foundation of China(11975113)。
文摘The isomeric ratio of^(184m,g)Re and the half-life of^(184g)Re were measured in the ^(185)Re(n,2n)^(184)Re reaction at 14.8 MeV,and the uncertainty was discussed in detail.The measurements were performed using the activation method implemented for a rhenium sample using the K-400 neutron generator at the Chinese Academy of Engineering Physics(CAEP).Isomeric state and ground state nuclei of ^(184)Re were identified by their γ-ray spectra.To eliminate the effect of the γ-ray emitted from the isomer on the counting of the ground state characteristic peaks,the isomeric ratio of^(184m,g)Re was calculated to be 0.29±0.11 according to the neutron activation cross-section formula.This result is consistent with previous data within the uncertainty and can be used to determine parameters that characterize the dependence of the level density on the excitation energy and angular momentum.Through exponential function fitting and a detailed discussion of the uncertainty evaluation,the half-life of^(184g)Re was determined as 35.43±0.16 d,which is consistent with the currently recommended value;however,the uncertainty assessment of the latter was barely documented.In addition,this study indicates that the half-life of the ground state can be obtained by eliminating the contamination of γ-rays emitted from the isomer,which provides the possibility of determining the half-lives of nuclides containing isomers.
基金Supported by an FRGS grant from the Ministry of Education,Malaysia,No.FRGS/2/2014/SG05/MUSM/03/1.
文摘BACKGROUND Glucagon-like peptide-1(GLP1)is an endogenous peptide that regulates blood glucose level.But its susceptibility to rapid metabolic degradation limits its therapeutic use.AIM To prepare GLP1-encapsulated nanosize particle with controlled release property to improve the systemic half-life of GLP1.METHODS GLP1 nanoparticles were prepared by complexation of GLP1 with carbonate apatite nanoparticles(CA NPs).The physicochemical properties of the CA NPs,the effects of GLP1-loaded CA NPs on cell viability,and the systemic bioavailability of GLP1 after CA NPs administration were determined.RESULTS The GLP1-loaded CA NPs was within 200 nm in size and stable in fetal bovine serum.The formulation did not affect the viability of human cell lines suggesting that the accumulation of CA NPs in target tissues is safe.In Sprague Dawley rats,the plasma GLP1 Levels as measured from the GLP1-loaded CA NPs-treated rats,were significantly higher than that of the control rats and free GLP1-treated rats at 1 h post-treatment(P<0.05),and the level remained higher than the other two groups for at least 4 h.CONCLUSION The GLP1-loaded CA NPs improved the plasma half-life of GLP1.The systemic bioavailability of GLP1 is longer than other GLP1 nanoparticles reported to date.
文摘A radioactive nucleus is characterized with an intrinsic half-life. However, for a nuclear species, the half-lives inneutral atoms could be very different from that in highly charged ions. The half-lives of some highly charged ionshave been directly measured at GSI for multiple motivations[1]. In the same case, the nuclear state(i:e the isomer)may be in the range of several tens of microseconds and their half-live can be measured using isochronous massspectrometry. The J = 8+ isomeric state in 94Ru was chosen to test this method. The half-life of this isomer is71 s [2] in neutral atoms, and the excitation energy is 2.64 MeV. The internal conversion coefficient of this decayin neutral atom is 0.335. So its half-life in the bare nucleus would be modified to be 94.78 s when the internalconversion channel is blocked.
文摘Protein-based therapeutics (PPTs) are drugs used to treat a variety of different conditions in the human body by alleviating enzymatic deficiencies, augmenting other proteins and drugs, modulating signal pathways, and more. However, many PPTs struggle from a short half-life due to degradation caused by irreversible protein aggregation in the bloodstream. Currently, the most researched strategies for improving the efficiency and longevity of PPTs are post-translational modifications (PTMs). The goal of our research was to determine which type of PTM increases longevity the most for each of three commonly-used therapeutic proteins by comparing the docking scores (DS) and binding free energies (BFE) from protein aggregation and reception simulations. DS and BFE values were used to create a quantitative index that outputs a relative number from −1 to 1 to show reduced performance, no change, or increased performance. Results showed that methylation was the most beneficial for insulin (p < 0.1) and human growth hormone (p < 0.0001), and both phosphorylation and methylation were somewhat optimal for erythropoietin (p < 0.1 and p < 0.0001, respectively). Acetylation consistently provided the worst benefits with the most negative indices, while methylation had the most positive indices throughout. However, PTM efficacy varied between PPTs, supporting previous studies regarding how each PTM can confer different benefits based on the unique structures of recipient proteins.
基金This workis financially supported bythe National Natural Science Foundation of China (Grant No.50479049) theNatural Science Foundation of Tianjin (Grant No.033804011)the Hi-tech Development Program(Grant No.2002AA64801006)
文摘Water exchange is an important hydrodynamic character of sea bays, and it is the basis for the study of the environmental capacity of sea bays. In this paper, a relation matrix is set up to describe the interaction among different areas of a sea bay, and to predict the water quality of those areas. The relation matrix is calculated based on the numerical results from a water quality model. This method is applied to the study of water exchange and the prediction of water quality of the Bohai Sea. The Bohai Sea is divided into five areas, and the effect of seasonal wind is taken into consideration. The results show a) the relation matrix can be used to study the water exchange among different areas and predict water quality of different areas at the respective characteristic time, b) the reduction of pollutant is dependent on both water exchange and initial distribution of the pollutant, and c) the half-life time of the pollutant is longer than the half-exchange time of the sea water.
基金supported by the Scientific ResearchFoundation for the Returned Overseas Chinese Scholars,State Education Ministry,the National Natural ScienceFoundation of China(No.30470918).
文摘3D-QSAR studies of persistent organic pollutants(POPs)screening for atmosphere persistence were performed by comparative molecular field analysis(CoMFA)and comparative molecular similarity index analysis(CoMSIA)methods.The mean and maximum half-life estimations for degradation in air of 49 UNEP POPs and possible POPs were modeled.Both groups’data have been modeled to obtain an average estimate and a predictive value for ranking and screening purposes.CoMFA and CoMSIA models have given cross-validation regre...
基金Project (No. 39790100) supported by the National Natural Science Foundation of China.
文摘A greenhouse experiment was conducted to investigate the effect of surface film-forming material (SFFM), a mixture of 16-18-octadecanols by emulsification, on water evaporation. Air-dried soil with distilled water was incubated firstly for 7 days to reestablish soil biological activity and then for another 7 days after treated with SFFM at rates of 0, 1, 2, 4, 6 and 8 g m-2, respectively. Everyday during the 7-day incubation after addition of SFFM, water losses due to evaporation were ~measured by an electronic balance. The rate of water evaporation with the addition of SFFM was reduced significantly compared with the control treatment and the effectiveness of SFFM on water evaporation reduced with time. According to the equation expressions of the effect of SFFM on water evaporation, the half-life of electiveness of SFFM on water evaporation was introduced and calculated to analyze quantitative relationship between the effectiveness of SFFM on water evaporation and the addition rate of SFFM. The calculated half-life increased with the addition rate of SFFM and the confidence of the calculated values of the half-life was high, suggesting that the half-life of effectiveness of SFFM on water evaporation could be described quantitatively and may be helpful for ameliorating application method of SFFM and screening surface-film forming materials in order to improve nitrogen fertilizer use efficiency in flooded rice fields.
基金Supported by Tripartite Joint Fund of Science and Technology Department of Guizhou Province(LH[2016]7278)Agricultural Science and Technology Project of Science and Technology Department of Guizhou Province(NZ[2013]3029)+1 种基金Tripartite Joint Fund of Science and Technology Department of Guizhou Province(Key Project)(JLKA[2012]03)Natural Science Research Project of Department of Education of Guizhou Province(2011054)~~
文摘A field experiment was employed to study the degradation of triadimefon and difenoconazole residues in strawberry and soil. The results showed that the degradation of both the two kinds of pesticides was in accordance with the first order kinetic equation. The half-lives of difenoconazole in strawberry fruit, strawberry stem leaf and soil were 4.09, 8.21 and 13.38 d, respectively; and the half-lives of triadimefon in strawberry fruit, strawberry stem and leaf and soil were 3.38, 5.31 and 15.64 d, respectively. The maximum residue limit (MRL) of difenoconazole in strawberry was recommended as 0.5 mg/kg, and 10% difenoconazole WG and 20% triadimefon EC should be applied four times with a safety interval of 7 d according to the amounts of 100 and 60 g a. i./hm2,respectively.
文摘Four kinds of plant materials (astragalus, azolla, rice straw and water hyacinth) were allowed to decompose for 10 years in two soils with different mineralogical characteristics in fields under upland and submerged conditions. Greater amounts of C and N from azolla were retained in soils throughout the 10-year experimental period compared to those from the other plant materials. The residual C Of all the plant materials in the two soils under upland conditions mineralized st rates corresponding to half-lives between 4.4-6.6 years,while the corresponding figures for thine under submerged conditions were between 6.5-13.1 years. Minerallization of residual organic N followed the same pattern as residual C. Compared to residual C, however, the mineralization rates of residual organic N in most cases were significantly lower and the percentages of added N regained in sons were higher. More N from plat materials was retained in the yellow-brown soil than in the red soil, but no consistent differences in the amounts of C from plant materials and in the mineralization rates of both residual C and residual organic N between the two soils could be found.
文摘The soils, tropical climate, and network of canals and rivers of southern Vietnam have created one of the most diverse tropical jungles and intensely cultivated landscapes of Southeast Asia. This paradise has a long history of numerous wars, foreign occupations, and most recently the Second Indochina War (aka the Vietnam War 1965-1972) which defoliated rain forests and ancient wetland mangroves and left behind contaminated soil and sediment hotspots. During this war, the United States (US) military sprayed 80 million liters of Agent Orange contaminated with the dioxin TCDD in a guerrilla war against communist insurgents. Agent Orange was a synthetic plant growth regulator comprised of equal amounts of two herbicides 2,4-dichloro phenoxyacetic acid C8H6Cl2O3 (2,4-D) and 2,4,5-trichlorophenoxyacetic acid C8H5Cl3O3 (2,4,5-T). TCDD, the dioxin, 2,3,7,8-tetrachlorodibenzodioxin (C12H4Cl4O2) was an unintended byproduct of the accelerated combustion process used in the manufacture of herbicides containing 2,4,5-T. Agent Orange has frequently been blamed for soil and sediment contamination and long-term human health problems;however, the true source of harm is the dioxin TCDD. Agent Orange has a short half-life of days and weeks after application to vegetation, and has not been found to persist, after 50 years, in the water or soils of southern Vietnam. However, the half-life of dioxin TCDD depends on where it is deposited and varies from 1 to 3 years on soil surfaces that have been fully exposed to sunlight, to as long as 20 to 50 years or more when buried in tropical subsoils, and more than 100 years in river and sea sediments. Dioxin TCDD was heavily concentrated in the US Air Force bases in Vietnam where the herbicides were stored, loaded on planes and helicopters for aerial spraying, and used extensively around military base perimeter fences as a security measure to prevent surprise attacks. Bien Hoa Air Force base, 40 km northeast of Ho Chi Minh City, continues to be one of the mega-hotspots where after 48 years the dioxin TCDD levels in fish and shrimp are still high and fishing is banned in ponds and lakes adjacent to the airbase. Although expensive, one of the most effective remediation to dioxin TCDD contaminated soils is incineration which is the recommended method of dioxin TCDD disposal.
文摘The binding of recombinant human macrophage colony-stimulating factor (M-CSF) soluble receptor (rh-M-CSF-sR) to membrane-bound macrophage colony stimulating factor (m-M-CSF) and the internalization and recycling of rh-M-CSF-sR/m-M-CSF complexes mediated by m-M-CSF were studied with a model of J6-1 cell line. The results indicated that m-M-CSF bound rh-M-CSF-sR with high affinity (Kd= 1.78×10 12 mol/L) and mediated a temperature- and energy-dependent internalization of rh-M-CSF-sR, and that internalized rh-M-CSF-sR could return to the cell surface in an m-M-CSF-bound state, suggesting that m-M-CSF may have a capability to mediate the internalization and recycling of rh-M-CSF-sR/m-M-CSF complexes. In addition, the half-lives of cell-associated M-CSF and its receptor of stimulated normal human cord blood mononuclear cells (CBMCs) and 4 leukemic cell lines were measured by indirect immunoflu-orescence and flow cytometry. The results showed that the half-lives of the various kinds of M-CSF isoforms and