The present study was designed to investigate the bioactive constituents ofXanthoceras sorbifolia in terms of amounts and their antioxidant, DNA scissiou protection, and ct-glucosidase inhibitory activities. Simultane...The present study was designed to investigate the bioactive constituents ofXanthoceras sorbifolia in terms of amounts and their antioxidant, DNA scissiou protection, and ct-glucosidase inhibitory activities. Simultaneous quantification of 10 X. sorbifolia constituents was carried out by a newly established ultra-high performance liquid chromatography-quadrupole mass spectrometry method （UHPLC-MS）, The antioxidant activities were evaluated by measuring DPPH radical scavenging and DNA scission protective activities. The a-glucosidase inhibitory activities were investigated by using an assay with a-glucosidase from Bacillus Stearothermophilus and disaccharidases from mouse intestine. We found that the wood ofX. sorbifolia was rich in phenolic compounds with the contents of catechin, epicatechin, myricetin, and dihydromyricetin being 0.12-0.19, 1.94-2.16, 0.77-0.91, and 6.76-7.89 mg.g-1, respectively. The four constituents strongly scavenged DPPH radicals （with ECs0 being 4.2, 3.8 and 5.7 μg-mL-1, respectively） and remarkably protected peroxyl radical-induced DNA strand scission （92.10%, 94.66%, 75.44% and 89.95% of protection, respectively, at a concentration of 10 μmol.L-1）. A dimeric flavan 3-ol, epigallocatechin-（4β→8, 2β→O-7）-epicatechin potently inhibited a-glucosidase with an IC50 value being as low as 1.2 μg.mL1. The established UHPLC-MS method could serve as a quality control tool for X. sorbifolia. In conclusion, the high contents of antioxidant and α-glucosidase inhibitory constituents in X. sorbifolia support its use as complementation of other therapeutic agents for metabolic disorders, such as diabetes and hypertension.展开更多
The frequent haze days around the Chinese capital of Beijing in recent years have aroused great attention owing to the detrimental effects on visibility and public health. To discover the potential health effects of t...The frequent haze days around the Chinese capital of Beijing in recent years have aroused great attention owing to the detrimental effects on visibility and public health. To discover the potential health effects of the haze, oxidative capacities of airborne particles collected in Beijing during haze and clear days were comparably assessed by a plasmid scission assay. Eleven water-soluble trace elements （As, Cd, Cr, Cu, Mn, Ni, Pb, V, Se, T1, and Zn） in the size-segregated airborne particles were quantitatively analyzed by inductively coupled plasma mass spectrometry, and most of the water- soluble trace elements were found to mainly concentrate in the fine particle size of 0.56-1.0 μm. In comparison with clear days, the mass concentrations of 11 analyzed water-soluble trace elements remarkably increased during haze days, and the oxidative capacities determined by the plasmid scission assay were markedly elevated accordingly during the haze days under the same dosage of particles as for those during clear days. Water-soluble trace elements in airborne particles, such as Cu, V, and particularly Zn, were found to have significantly positive correlations with the plasmid DNA damage rates. Because Cu, V, and Zn have been considered as bioavailable elements, the evident increase of these elements during haze days may be greatly harmful to human health.展开更多
Microplastic pollution has become one of the most concerned focuses in the world.Among many treatment methods,photocatalysis is considered to be one of the most environmentally friendly methods.In this work,the photod...Microplastic pollution has become one of the most concerned focuses in the world.Among many treatment methods,photocatalysis is considered to be one of the most environmentally friendly methods.In this work,the photodegradation behavior of polyamide microplastics is studied by using polyamide 6(PA6)as model microplastics and FeCl_(3) as catalyst.It is hoped that the PA6 fiber can be effectively degraded by utilizing the strong oxidizing active species that can be produced after FeCl_(3) is irradiated in water.The results shows that PA6 fiber can be almost completely degraded after 10 days of irradiation in FeCl_(3) aqueous solution,indicating that it is promising to use this new method to solve the problem of PA6type microplastics.In addition,the chain scission mechanism and degradation process of PA6 are analyzed in detail by ultra-high performance liquid chromatography-tandem mass spectrometry(UPLC-MS),which provides a new insight for the study of polymer degradation mechanism.展开更多
We calculate the three-dimensional potential energy surface(PES)for the fission of the compound nucleus^(236)U using covariant density functional theory with constraints on the axial quadrupole and octupole deformatio...We calculate the three-dimensional potential energy surface(PES)for the fission of the compound nucleus^(236)U using covariant density functional theory with constraints on the axial quadrupole and octupole deformations(β_(2),β_(3))coexistence of the elongated and compact fission modes is predicted for comes shallow across a large range of quadrupole and octupole deformations for small scission line in the(β_(2),β_(3))plane extends to a shallow band,leading to fluctuations of several to ten MeV in the estimated total kinetic energies and of several to approximately ten nucleons in the fragment masses.展开更多
Autophagy is essential for the maintenance of cellular homeostasis and its dysfunction has been linked to various diseases.Autophagy is a membrane driven process and tightly regulated by membrane-associated proteins.H...Autophagy is essential for the maintenance of cellular homeostasis and its dysfunction has been linked to various diseases.Autophagy is a membrane driven process and tightly regulated by membrane-associated proteins.Here,we summarized membrane lipid composition,and membrane-associated proteins relevant to autophagy from a spatiotemporal perspective.In particular,we focused on three important membrane remodeling processes in autophagy,lipid transfer for phagophore elongation,membrane scission for phago-phore closure,and autophagosome-lysosome membrane fusion.We discussed the significance of the discoveries in this field and possible avenues to follow for future studies.Finally,we summarized the membrane-associated biochemical techniques and assays used to study membrane properties,with a discussion of their applications in autophagy.展开更多
3-Methoxy-, 3, 5-dimethoxy-, and 3-phenyl-4-hydroxyacetophenones suffered alkyl carbonyl C-C bond scission to yield 4-hydroxybenzoate esters and 4-isopropenylphenols under standard conditions of ethylene ketal formati...3-Methoxy-, 3, 5-dimethoxy-, and 3-phenyl-4-hydroxyacetophenones suffered alkyl carbonyl C-C bond scission to yield 4-hydroxybenzoate esters and 4-isopropenylphenols under standard conditions of ethylene ketal formation; the latter underwent in situ dimerization, cyclization, and rearrangement to give substituted indanols. The isopropenylphenol derived from 3,5-ditertbutyl-4-hydroxyacetophenone did not dimerize but condensed with its precursor to yield a substituted diphenylpropanone. 3-nitro-, 3,5-dinitro-, and 3,5-dibromo-4-hydroxyacetophenones on the other hand reacted normally to give ethylene ketals in good yields.展开更多
AlCl3-mediated cleavage of ethereal methyl–oxygen bond in aroylated 2,7-dimethoxynaphthalene compounds proceeds chemospecifically and regioselectively. The ethereal bond at the β(2)-position of 1-monoaroylated 2,7-d...AlCl3-mediated cleavage of ethereal methyl–oxygen bond in aroylated 2,7-dimethoxynaphthalene compounds proceeds chemospecifically and regioselectively. The ethereal bond at the β(2)-position of 1-monoaroylated 2,7-dimethoxynaphthalene is cleaved readily and predominantly against the β(7)-position, whereas scission of β-ethereal bonds of 1,8-diaroylated 2,7-dimethoxynaphthalene hardly undergoes like the non-aroylated mother frame compound of 2,7-dimethoxynaphthalene.展开更多
The first three-fold and four-fold fragmentation measurements in hot compound nuclei pro-duced in the reactions of a 25 MeV/u <sup>40</sup>At beam with targets of <sup>209</sup>Bi,<sup>19...The first three-fold and four-fold fragmentation measurements in hot compound nuclei pro-duced in the reactions of a 25 MeV/u <sup>40</sup>At beam with targets of <sup>209</sup>Bi,<sup>197</sup>Au,<sup>159</sup>Tb,<sup>115</sup>In,<sup>103</sup>Rh,and<sup>93</sup>Nb are presented.Various distributions are measured for these fragments,including distributions of ve-locities,relative velocities,angles,relative angles,masses,fragment mass ratios,total kinetic energies（TKE）,as well as the yield ratios of three-fold fragmentation to fission P<sub>32</sub> and the time difference △t be-tween two scissions after the formation of one compound nucleus.展开更多
Irradiation effects of γ-radiation on the physical and electrical properties of polycarbonate (Makrofol-E( film has been studied to be able to investigate the dielectric response of irradiated polymers for a wide ran...Irradiation effects of γ-radiation on the physical and electrical properties of polycarbonate (Makrofol-E( film has been studied to be able to investigate the dielectric response of irradiated polymers for a wide range of fluence and frequency. The dielectric constant (ε') The loss tangent (tanδ), dielectric loss factor (ε''), the a.c electrical conductivity (σ) and the relaxation time (τ), were measured in the frequency range from (40) Hz to (4) MHz. These samples were irradiated by means of γ-rays from 10 up to 200 KGy. The change in different properties as a function of absorbed dose was studied. Degradation of the polymers leading to amorphisation was observed by increasing the absorbed γ- dose. The induced changes in the electrical conductivity due to γ-rays irradiation of Makrofol-E provide a better method for γ -dose measurements. A semi-empirical equation was developed to use Makrofol-E as a dielectric dosimeter. Furthermore, Makrofol-E has much greater resistance to radiation damage;the attained results suggested strongly the applicability of Makrofol-E to be used in medical products applications.展开更多
A new statistical method for systematizing the nuclei fission fragments, investigation of their mass and charge spectra and neutron fission parameters has been suggested. In proposed method, the mass and charge yields...A new statistical method for systematizing the nuclei fission fragments, investigation of their mass and charge spectra and neutron fission parameters has been suggested. In proposed method, the mass and charge yields of nucleons are determined from the equilibrium conditions of the nuclear fragments post-fission ensemble. Here we consider protons and neutrons of different fragments as statistically non-equivalent. The abilities of the proposed statistical method for explanation of the U, Pa, Th, Ac and Ra post-fission fragments ordering and neutron emission function calculation have been demonstrated.展开更多
A special dye-stuff was chosen and made to be absorbed by the cells of tumor, and then the cells were irradiated under a laser beam with a certain wavelength in order to cure cancer. This is known as laser-chemical th...A special dye-stuff was chosen and made to be absorbed by the cells of tumor, and then the cells were irradiated under a laser beam with a certain wavelength in order to cure cancer. This is known as laser-chemical therapy. Although photosensitization has been developed in the early 20th century and a number of works describing its effect展开更多
Antimutagenic and DNA protective effect of an extract VinOserae from Vitis vinifera grapes on oxidative DNA damage was investigated. The extract’s ability to inhibit mutagenicity induced by tert-butyl hydroperoxide (...Antimutagenic and DNA protective effect of an extract VinOserae from Vitis vinifera grapes on oxidative DNA damage was investigated. The extract’s ability to inhibit mutagenicity induced by tert-butyl hydroperoxide (t-BHP) and hydrogen peroxide (H2O2) was determined with Ames test using Salmonella typhimurium His? TA102 strain. Inhibition values of 44.2% and 67.0% were detected for t-BHP and H2O2, respectively. A protective ability of the extract against DNA strand scission induced by hydroxyl radicals was studied with plasmid pBluescript II SK(-). The analysis of DNA strand breaks in plasmid DNA showed a significant inhibition of DNA damage.展开更多
We design a ratiometric fluo rescent sensing platform for bleomycin(BLM) by using proximity-dependent DNA-templated silver nanoclusters(DNA-AgNCs) probe.This ratiometric sensing system is constructed with DNA-AgNCs as...We design a ratiometric fluo rescent sensing platform for bleomycin(BLM) by using proximity-dependent DNA-templated silver nanoclusters(DNA-AgNCs) probe.This ratiometric sensing system is constructed with DNA-AgNCs as single fluorophore.The proposed strategy is based on the two following facts:(1) a covert DNA can approach and transform the DNA-AgNCs with green emission(G-DNA-AgNCs) into red emission through hybridization reaction.(2) The specific cleavage of the convert DNA by BLM in the presence of Fe(Ⅱ) inhibits the discoloration of G-DNA-AgNCs.Thus,benefiting from the specific recognition of BLM and unique properties of G-DNA-AgNCs,a hignly-sensitive ratiometric sensor for BLM has been successfully developed.The detection limit is as low as 30 pmol/L.This label-free fluorescence probe possesses advantages of convenient synthetic process and low cost.Moreover,this ratiometric method has been applied to the detection of BLM in human serum samples,illustrating a promising tool for analysis of BLM in cancer therapy.展开更多
Chitosan （CS） is expected to be an ideal gene carrier for its high biosafety. In this work, CS with low molecular weight were prepared through the γ-ray radiation on the acetic acid solution of CS. The CS chains we...Chitosan （CS） is expected to be an ideal gene carrier for its high biosafety. In this work, CS with low molecular weight were prepared through the γ-ray radiation on the acetic acid solution of CS. The CS chains were scissioned under the γ-ray radiation, and the molecu- lar weight （MW） of CS decreased with the absorbed dose. When the absorbed dose was above 30 kGy, the molecular weight of CS decreased about an order of magnitude. The γ-ray-radiation-scissioned CS can effectively bind with plasmid （pEGFP） through complex coacervation method, forming pEGFP/γ-ray-radiation-scissioned CS complex particles with a size of 200-300 nm. The complex particles have good stability and little cytotoxicity. The in vitro gene transfection efficiencies of the pEGFP/γ-ray-radiation-scissioned CS complex particles were investigated by fluorescence microscope and flow cytometry. The results showed that the gene vectors using γ-ray-radiation-scissioned CS as the carrier will possess better gene transfection efficiency than those using natural high-MW CS as the carrier. The higher the absorbed dose, the smaller the MW of CS and the better transfection efficiency of the corresponding gene vector. This work provides a green and simple method on the preparation of CS-based gene vectors with high efficiency and biosafety.展开更多
The influence of the neck parameter on the fission dynamics at low excitation energy is studied based on the three-dimensional Langevin approach,in which the nuclear shape is described with the two-center shell model(...The influence of the neck parameter on the fission dynamics at low excitation energy is studied based on the three-dimensional Langevin approach,in which the nuclear shape is described with the two-center shell model(TCSM)parametrization,and the elongation,mass asymmetry,and fragment deformation are set to be the generalized coordinates of the Langevin equation.We first study the influence of the neck parameter on the scission configuration.We find that there is almost no obvious correlation between the neck parameter and mass asymmetryηat the scission point,indicating that has no evident impact on the fragment mass distribution.The elongation Z_(0)=R_(0) and its correlation with the mass asymmetryηat the scission point are clearly influenced by the neck parameter,which has a strong effect on the total kinetic energy(TKE)distribution of the fragments.The pre-neutron emission fragment mass distributions for 14 MeV n+^(233;235;238)U and^(239)Pu are calculated,and then,based on these results,the post-neutron emission fragment mass distributions are obtained by using the experimental data of prompt neutron emission.The calculated post-neutron emission fragment mass distributions can reproduce the experimental data well.The TKE distributions for 14 MeV n+^(235)U fission are calculated for ε=0.25,0.35,and 0.45,and the results show that the TKE distribution cannot be described very well for the three cases.However,the trend of the calculated TKE distribution withεis just as expected from the scission configuration calculations.The results with ε=0.35 present a better agreement with the experiment data compared with the other two cases.展开更多
This work extends our previous understanding concerning the nonlinear responses of entangled polymer solutions and melts to large external deformation in both simple shear and uniaxial extension. Many similarities hav...This work extends our previous understanding concerning the nonlinear responses of entangled polymer solutions and melts to large external deformation in both simple shear and uniaxial extension. Many similarities have recently been identified for both step strain and startup continuous deformation, including elastic yielding, i.e., chain disentanglement after cessation of shear or extension, and emergence of a yield point during startup deformation that involves a deformation rate in excess of the dominant molecular relaxation rate. At a sufficiently high constant Hencky rate, uniaxial extension of an entangled melt is known to produce window-glass-like rupture. The present study provides evidence against the speculation that chain entanglements tie up into "dead knots" in constant-rate extension because of the exponentially growing chain stretching with time. In particular, it is shown that even Instron-style tensile stretching, i.e., extending a specimen by applying a constant velocity on both ends, results in rupture. Yet, in the same rate range, the same entangled melt only yields in simple shear, and the resulting shear banding is clearly not a characteristic of rupture. Thus, we conclude that chain entanglements respond to simple shear in the manner of yielding whereas uniaxial extension is rather effective in causing some entanglements to lock up, making it impossible for the entanglement network to yield at high rates.展开更多
基金supported by National Natural Science Foundation of China(No.81360474)
文摘The present study was designed to investigate the bioactive constituents ofXanthoceras sorbifolia in terms of amounts and their antioxidant, DNA scissiou protection, and ct-glucosidase inhibitory activities. Simultaneous quantification of 10 X. sorbifolia constituents was carried out by a newly established ultra-high performance liquid chromatography-quadrupole mass spectrometry method （UHPLC-MS）, The antioxidant activities were evaluated by measuring DPPH radical scavenging and DNA scission protective activities. The a-glucosidase inhibitory activities were investigated by using an assay with a-glucosidase from Bacillus Stearothermophilus and disaccharidases from mouse intestine. We found that the wood ofX. sorbifolia was rich in phenolic compounds with the contents of catechin, epicatechin, myricetin, and dihydromyricetin being 0.12-0.19, 1.94-2.16, 0.77-0.91, and 6.76-7.89 mg.g-1, respectively. The four constituents strongly scavenged DPPH radicals （with ECs0 being 4.2, 3.8 and 5.7 μg-mL-1, respectively） and remarkably protected peroxyl radical-induced DNA strand scission （92.10%, 94.66%, 75.44% and 89.95% of protection, respectively, at a concentration of 10 μmol.L-1）. A dimeric flavan 3-ol, epigallocatechin-（4β→8, 2β→O-7）-epicatechin potently inhibited a-glucosidase with an IC50 value being as low as 1.2 μg.mL1. The established UHPLC-MS method could serve as a quality control tool for X. sorbifolia. In conclusion, the high contents of antioxidant and α-glucosidase inhibitory constituents in X. sorbifolia support its use as complementation of other therapeutic agents for metabolic disorders, such as diabetes and hypertension.
基金supported by the"Strategic Priority Research Program-Formation Mechanism and Control Strategies of Haze in China"of the Chinese Academy of Sciences(No.XDB05010100),the National Basic Research Program(973)of China(No.2013CB228503,2010CB732304)
文摘The frequent haze days around the Chinese capital of Beijing in recent years have aroused great attention owing to the detrimental effects on visibility and public health. To discover the potential health effects of the haze, oxidative capacities of airborne particles collected in Beijing during haze and clear days were comparably assessed by a plasmid scission assay. Eleven water-soluble trace elements （As, Cd, Cr, Cu, Mn, Ni, Pb, V, Se, T1, and Zn） in the size-segregated airborne particles were quantitatively analyzed by inductively coupled plasma mass spectrometry, and most of the water- soluble trace elements were found to mainly concentrate in the fine particle size of 0.56-1.0 μm. In comparison with clear days, the mass concentrations of 11 analyzed water-soluble trace elements remarkably increased during haze days, and the oxidative capacities determined by the plasmid scission assay were markedly elevated accordingly during the haze days under the same dosage of particles as for those during clear days. Water-soluble trace elements in airborne particles, such as Cu, V, and particularly Zn, were found to have significantly positive correlations with the plasmid DNA damage rates. Because Cu, V, and Zn have been considered as bioavailable elements, the evident increase of these elements during haze days may be greatly harmful to human health.
基金supported by the Natural Science Foundation of Zhejiang Province(No.LDQ23E030001)。
文摘Microplastic pollution has become one of the most concerned focuses in the world.Among many treatment methods,photocatalysis is considered to be one of the most environmentally friendly methods.In this work,the photodegradation behavior of polyamide microplastics is studied by using polyamide 6(PA6)as model microplastics and FeCl_(3) as catalyst.It is hoped that the PA6 fiber can be effectively degraded by utilizing the strong oxidizing active species that can be produced after FeCl_(3) is irradiated in water.The results shows that PA6 fiber can be almost completely degraded after 10 days of irradiation in FeCl_(3) aqueous solution,indicating that it is promising to use this new method to solve the problem of PA6type microplastics.In addition,the chain scission mechanism and degradation process of PA6 are analyzed in detail by ultra-high performance liquid chromatography-tandem mass spectrometry(UPLC-MS),which provides a new insight for the study of polymer degradation mechanism.
基金Supported by the National Natural Science Foundation of China(11875225,11790325,11790320)the Special Fund from the China Nuclear Data Center+1 种基金the Fundamental Research Funds for the Central Universitiesthe Fok Ying-Tong Education Foundation。
文摘We calculate the three-dimensional potential energy surface(PES)for the fission of the compound nucleus^(236)U using covariant density functional theory with constraints on the axial quadrupole and octupole deformations(β_(2),β_(3))coexistence of the elongated and compact fission modes is predicted for comes shallow across a large range of quadrupole and octupole deformations for small scission line in the(β_(2),β_(3))plane extends to a shallow band,leading to fluctuations of several to ten MeV in the estimated total kinetic energies and of several to approximately ten nucleons in the fragment masses.
基金grants from NSFC(91754205,91957204,31771523,31870830 and 31801170)MOST(2019YFA0508602)+2 种基金Shanghai Municipal Science and Technology Project(20JC1411100)Program of Shanghai Academic/Technology Research Leader(19XD1402200)innovative research team of high-level local universities in Shanghai.
文摘Autophagy is essential for the maintenance of cellular homeostasis and its dysfunction has been linked to various diseases.Autophagy is a membrane driven process and tightly regulated by membrane-associated proteins.Here,we summarized membrane lipid composition,and membrane-associated proteins relevant to autophagy from a spatiotemporal perspective.In particular,we focused on three important membrane remodeling processes in autophagy,lipid transfer for phagophore elongation,membrane scission for phago-phore closure,and autophagosome-lysosome membrane fusion.We discussed the significance of the discoveries in this field and possible avenues to follow for future studies.Finally,we summarized the membrane-associated biochemical techniques and assays used to study membrane properties,with a discussion of their applications in autophagy.
文摘3-Methoxy-, 3, 5-dimethoxy-, and 3-phenyl-4-hydroxyacetophenones suffered alkyl carbonyl C-C bond scission to yield 4-hydroxybenzoate esters and 4-isopropenylphenols under standard conditions of ethylene ketal formation; the latter underwent in situ dimerization, cyclization, and rearrangement to give substituted indanols. The isopropenylphenol derived from 3,5-ditertbutyl-4-hydroxyacetophenone did not dimerize but condensed with its precursor to yield a substituted diphenylpropanone. 3-nitro-, 3,5-dinitro-, and 3,5-dibromo-4-hydroxyacetophenones on the other hand reacted normally to give ethylene ketals in good yields.
文摘AlCl3-mediated cleavage of ethereal methyl–oxygen bond in aroylated 2,7-dimethoxynaphthalene compounds proceeds chemospecifically and regioselectively. The ethereal bond at the β(2)-position of 1-monoaroylated 2,7-dimethoxynaphthalene is cleaved readily and predominantly against the β(7)-position, whereas scission of β-ethereal bonds of 1,8-diaroylated 2,7-dimethoxynaphthalene hardly undergoes like the non-aroylated mother frame compound of 2,7-dimethoxynaphthalene.
基金The project partially supported by the National Natural Science Foundation of China
文摘The first three-fold and four-fold fragmentation measurements in hot compound nuclei pro-duced in the reactions of a 25 MeV/u <sup>40</sup>At beam with targets of <sup>209</sup>Bi,<sup>197</sup>Au,<sup>159</sup>Tb,<sup>115</sup>In,<sup>103</sup>Rh,and<sup>93</sup>Nb are presented.Various distributions are measured for these fragments,including distributions of ve-locities,relative velocities,angles,relative angles,masses,fragment mass ratios,total kinetic energies（TKE）,as well as the yield ratios of three-fold fragmentation to fission P<sub>32</sub> and the time difference △t be-tween two scissions after the formation of one compound nucleus.
文摘Irradiation effects of γ-radiation on the physical and electrical properties of polycarbonate (Makrofol-E( film has been studied to be able to investigate the dielectric response of irradiated polymers for a wide range of fluence and frequency. The dielectric constant (ε') The loss tangent (tanδ), dielectric loss factor (ε''), the a.c electrical conductivity (σ) and the relaxation time (τ), were measured in the frequency range from (40) Hz to (4) MHz. These samples were irradiated by means of γ-rays from 10 up to 200 KGy. The change in different properties as a function of absorbed dose was studied. Degradation of the polymers leading to amorphisation was observed by increasing the absorbed γ- dose. The induced changes in the electrical conductivity due to γ-rays irradiation of Makrofol-E provide a better method for γ -dose measurements. A semi-empirical equation was developed to use Makrofol-E as a dielectric dosimeter. Furthermore, Makrofol-E has much greater resistance to radiation damage;the attained results suggested strongly the applicability of Makrofol-E to be used in medical products applications.
文摘A new statistical method for systematizing the nuclei fission fragments, investigation of their mass and charge spectra and neutron fission parameters has been suggested. In proposed method, the mass and charge yields of nucleons are determined from the equilibrium conditions of the nuclear fragments post-fission ensemble. Here we consider protons and neutrons of different fragments as statistically non-equivalent. The abilities of the proposed statistical method for explanation of the U, Pa, Th, Ac and Ra post-fission fragments ordering and neutron emission function calculation have been demonstrated.
基金Project supported by the National Natural Science Foundation of China
文摘A special dye-stuff was chosen and made to be absorbed by the cells of tumor, and then the cells were irradiated under a laser beam with a certain wavelength in order to cure cancer. This is known as laser-chemical therapy. Although photosensitization has been developed in the early 20th century and a number of works describing its effect
文摘Antimutagenic and DNA protective effect of an extract VinOserae from Vitis vinifera grapes on oxidative DNA damage was investigated. The extract’s ability to inhibit mutagenicity induced by tert-butyl hydroperoxide (t-BHP) and hydrogen peroxide (H2O2) was determined with Ames test using Salmonella typhimurium His? TA102 strain. Inhibition values of 44.2% and 67.0% were detected for t-BHP and H2O2, respectively. A protective ability of the extract against DNA strand scission induced by hydroxyl radicals was studied with plasmid pBluescript II SK(-). The analysis of DNA strand breaks in plasmid DNA showed a significant inhibition of DNA damage.
基金supported by the National Natural Science Foundation of China (No.21775088)。
文摘We design a ratiometric fluo rescent sensing platform for bleomycin(BLM) by using proximity-dependent DNA-templated silver nanoclusters(DNA-AgNCs) probe.This ratiometric sensing system is constructed with DNA-AgNCs as single fluorophore.The proposed strategy is based on the two following facts:(1) a covert DNA can approach and transform the DNA-AgNCs with green emission(G-DNA-AgNCs) into red emission through hybridization reaction.(2) The specific cleavage of the convert DNA by BLM in the presence of Fe(Ⅱ) inhibits the discoloration of G-DNA-AgNCs.Thus,benefiting from the specific recognition of BLM and unique properties of G-DNA-AgNCs,a hignly-sensitive ratiometric sensor for BLM has been successfully developed.The detection limit is as low as 30 pmol/L.This label-free fluorescence probe possesses advantages of convenient synthetic process and low cost.Moreover,this ratiometric method has been applied to the detection of BLM in human serum samples,illustrating a promising tool for analysis of BLM in cancer therapy.
基金This work was supported by the National Natural Science Foundation of China （No.81171829, No.51473152, and No.51573175） and the Fundamental Research hinds for the Central Universities （WK2060200012, WK3450000001）. We also thank Prof. Li-hua Yang and Prof. Ye-zi You at the University of Science and Technology of China （USTC） for their kind help ill providing experimental reagents and instrunlents.
文摘Chitosan （CS） is expected to be an ideal gene carrier for its high biosafety. In this work, CS with low molecular weight were prepared through the γ-ray radiation on the acetic acid solution of CS. The CS chains were scissioned under the γ-ray radiation, and the molecu- lar weight （MW） of CS decreased with the absorbed dose. When the absorbed dose was above 30 kGy, the molecular weight of CS decreased about an order of magnitude. The γ-ray-radiation-scissioned CS can effectively bind with plasmid （pEGFP） through complex coacervation method, forming pEGFP/γ-ray-radiation-scissioned CS complex particles with a size of 200-300 nm. The complex particles have good stability and little cytotoxicity. The in vitro gene transfection efficiencies of the pEGFP/γ-ray-radiation-scissioned CS complex particles were investigated by fluorescence microscope and flow cytometry. The results showed that the gene vectors using γ-ray-radiation-scissioned CS as the carrier will possess better gene transfection efficiency than those using natural high-MW CS as the carrier. The higher the absorbed dose, the smaller the MW of CS and the better transfection efficiency of the corresponding gene vector. This work provides a green and simple method on the preparation of CS-based gene vectors with high efficiency and biosafety.
基金Supported by the National Natural Science Foundation of China(12105369,11790324,11790325,11790323,11790320)the Continuous Basic Scientific Research Project(WDJC-2019-09)。
文摘The influence of the neck parameter on the fission dynamics at low excitation energy is studied based on the three-dimensional Langevin approach,in which the nuclear shape is described with the two-center shell model(TCSM)parametrization,and the elongation,mass asymmetry,and fragment deformation are set to be the generalized coordinates of the Langevin equation.We first study the influence of the neck parameter on the scission configuration.We find that there is almost no obvious correlation between the neck parameter and mass asymmetryηat the scission point,indicating that has no evident impact on the fragment mass distribution.The elongation Z_(0)=R_(0) and its correlation with the mass asymmetryηat the scission point are clearly influenced by the neck parameter,which has a strong effect on the total kinetic energy(TKE)distribution of the fragments.The pre-neutron emission fragment mass distributions for 14 MeV n+^(233;235;238)U and^(239)Pu are calculated,and then,based on these results,the post-neutron emission fragment mass distributions are obtained by using the experimental data of prompt neutron emission.The calculated post-neutron emission fragment mass distributions can reproduce the experimental data well.The TKE distributions for 14 MeV n+^(235)U fission are calculated for ε=0.25,0.35,and 0.45,and the results show that the TKE distribution cannot be described very well for the three cases.However,the trend of the calculated TKE distribution withεis just as expected from the scission configuration calculations.The results with ε=0.35 present a better agreement with the experiment data compared with the other two cases.
基金supported, in part, by the National Science Foundation of the United States (DMR-0821697, CMMI-0926522, DMR-1105135)
文摘This work extends our previous understanding concerning the nonlinear responses of entangled polymer solutions and melts to large external deformation in both simple shear and uniaxial extension. Many similarities have recently been identified for both step strain and startup continuous deformation, including elastic yielding, i.e., chain disentanglement after cessation of shear or extension, and emergence of a yield point during startup deformation that involves a deformation rate in excess of the dominant molecular relaxation rate. At a sufficiently high constant Hencky rate, uniaxial extension of an entangled melt is known to produce window-glass-like rupture. The present study provides evidence against the speculation that chain entanglements tie up into "dead knots" in constant-rate extension because of the exponentially growing chain stretching with time. In particular, it is shown that even Instron-style tensile stretching, i.e., extending a specimen by applying a constant velocity on both ends, results in rupture. Yet, in the same rate range, the same entangled melt only yields in simple shear, and the resulting shear banding is clearly not a characteristic of rupture. Thus, we conclude that chain entanglements respond to simple shear in the manner of yielding whereas uniaxial extension is rather effective in causing some entanglements to lock up, making it impossible for the entanglement network to yield at high rates.
