2005 Vol. 22, No. 2
Display Method:
2005, 22(2): 153-166.
doi: 10.11804/NuclPhysRev.22.02.153
Abstract:
Status of theoretical studies on superheavy nuclei is simply reviewed.We investigate the influence of nuclear deformation on halflives of α decay for
long lifetime nuclei beyond 208Pb. The range of the validity of relativistic meanfield model is analyzed and discussed. The conservation of parity in αdecay, clusterradioactivity, and spontaneous fission of nuclei is stressed. New views on the properties of superheavy nuclei are presented.
Status of theoretical studies on superheavy nuclei is simply reviewed.We investigate the influence of nuclear deformation on halflives of α decay for
long lifetime nuclei beyond 208Pb. The range of the validity of relativistic meanfield model is analyzed and discussed. The conservation of parity in αdecay, clusterradioactivity, and spontaneous fission of nuclei is stressed. New views on the properties of superheavy nuclei are presented.
Low lying Spectra and E2 Transition Rates in Even-even 142—164Dy Isotopes in Interaction Boson Model
2005, 22(2): 167-171.
doi: 10.11804/NuclPhysRev.22.02.167
Abstract:
Spectra and E2 transition rates for the eveneven 142-164Dy isotopes are studied in the framework of the interacting boson model. A schematic Hamiltonian capable of describing their spectra and transition is used. It is found that the eveneven 142-164Dy isotopes are in the transition from U(5)to SU(3) dynamical symmetry.
Spectra and E2 transition rates for the eveneven 142-164Dy isotopes are studied in the framework of the interacting boson model. A schematic Hamiltonian capable of describing their spectra and transition is used. It is found that the eveneven 142-164Dy isotopes are in the transition from U(5)to SU(3) dynamical symmetry.
2005, 22(2): 172-179.
doi: 10.11804/NuclPhysRev.22.02.172
Abstract:
It is systematically observed that the B(M1)/B(E2) plots with the increasing of rotational frequency, behaves as a socalled parabolalike shape in the π h11/2 νi13/2 bands of rareearth doubly odd nuclei (i.e., the B(M1)/B(E2) ratios increase rapidly after a certain rotational frequency). Such a phenomenon is discussed based on the formula of magnetic dipole reduced transition probability deduced from the Cranking Shell Model and Particle Rotor Model respectively. It is pointed out that, the occurrence of this behavior is closely related to the alignment nature of the νi 13/2 quasineutron. The increasing of B(M1)/B(E2) occurring at large frequency approaching the second BC crossing can be understood as mainly resulted from the mixing of wave function with the 4 quasiparticle band caused by the band crossing. Insight into the angular momentum coupling scheme between the quasiparticles and collective core in the π h11/2 νi 13/2 structures of rare earth doubly odd nuclei is gained by analyzing the increasing behavior of B(M1)/B(E2) ratios occurring at low rotational frequency.
It is systematically observed that the B(M1)/B(E2) plots with the increasing of rotational frequency, behaves as a socalled parabolalike shape in the π h11/2 νi13/2 bands of rareearth doubly odd nuclei (i.e., the B(M1)/B(E2) ratios increase rapidly after a certain rotational frequency). Such a phenomenon is discussed based on the formula of magnetic dipole reduced transition probability deduced from the Cranking Shell Model and Particle Rotor Model respectively. It is pointed out that, the occurrence of this behavior is closely related to the alignment nature of the νi 13/2 quasineutron. The increasing of B(M1)/B(E2) occurring at large frequency approaching the second BC crossing can be understood as mainly resulted from the mixing of wave function with the 4 quasiparticle band caused by the band crossing. Insight into the angular momentum coupling scheme between the quasiparticles and collective core in the π h11/2 νi 13/2 structures of rare earth doubly odd nuclei is gained by analyzing the increasing behavior of B(M1)/B(E2) ratios occurring at low rotational frequency.
2005, 22(2): 180-185.
doi: 10.11804/NuclPhysRev.22.02.180
Abstract:
From the spinorial form of the Lorentzforce equation, the problems about axial electric field and axial magnetic field of charge motion in electromagnetic fields, as well as planewave pulse and Larmor power have been discussed in this paper. These problems are the foundation of studying the autoresonance laser accelerator (ALA).
From the spinorial form of the Lorentzforce equation, the problems about axial electric field and axial magnetic field of charge motion in electromagnetic fields, as well as planewave pulse and Larmor power have been discussed in this paper. These problems are the foundation of studying the autoresonance laser accelerator (ALA).
2005, 22(2): 186-189.
doi: 10.11804/NuclPhysRev.22.02.186
Abstract:
： In CSRe electron cooling device， a special electron gun which can produce variable profile electron beam with different size and density distribution was adopted for decreasing ion losses. Electrostatic bending device was used for reducing electron beam losses and improving vacuum condition. The instability of the electron beam is suppressed because the secondary electrons from collector would come back to the collector in the same orbit finally. Longitudinal magnetic field with parallelism better than 10-4 was achieved by adopting of independent high precise solenoid coils at cooling section. In this case， the r.m.s deviations of the transverse magnetic field at cooling section in horizontal and vertical direction are 3.298×10-5 and 2.458×10-5 respectively. The characters of the gun and collector were investigated. The results were presented and indicate that it achieves the design purpose very well.
： In CSRe electron cooling device， a special electron gun which can produce variable profile electron beam with different size and density distribution was adopted for decreasing ion losses. Electrostatic bending device was used for reducing electron beam losses and improving vacuum condition. The instability of the electron beam is suppressed because the secondary electrons from collector would come back to the collector in the same orbit finally. Longitudinal magnetic field with parallelism better than 10-4 was achieved by adopting of independent high precise solenoid coils at cooling section. In this case， the r.m.s deviations of the transverse magnetic field at cooling section in horizontal and vertical direction are 3.298×10-5 and 2.458×10-5 respectively. The characters of the gun and collector were investigated. The results were presented and indicate that it achieves the design purpose very well.
2005, 22(2): 190-192.
doi: 10.11804/NuclPhysRev.22.02.190
Abstract:
According to the problems found in the period of running for more than 10 years in the injector SFC(Sector Focusing Cyclotron) of Heavy Ion Research Facility in Lanzhou， an extensive improvement included vacuum pressure， distribution of magnetic field as well as RF system was carried out in recent years. The practice in beam tuning and operation for more than half year indicated that the status of SFC is improved obviously.
According to the problems found in the period of running for more than 10 years in the injector SFC(Sector Focusing Cyclotron) of Heavy Ion Research Facility in Lanzhou， an extensive improvement included vacuum pressure， distribution of magnetic field as well as RF system was carried out in recent years. The practice in beam tuning and operation for more than half year indicated that the status of SFC is improved obviously.
2005, 22(2): 193-197.
doi: 10.11804/NuclPhysRev.22.02.193
Abstract:
Using energetic cluster as projectile is a unique way to produce simultaneous impacts of several atoms and deposit extremely high energy density in a very small area. The cluster impingement on solids has exhibited some nonlinear effects not presented in collisions of individual atoms with those solids. The study of the secondary ion emissions can give insight into the energy deposition and relaxation steps of the clustersolid interaction. The dependence of the yields of secondary ion emission induced by clusters on the energy of clusters,cluster sizes,charge states and material structures of the targets was reviewed in this paper.
Using energetic cluster as projectile is a unique way to produce simultaneous impacts of several atoms and deposit extremely high energy density in a very small area. The cluster impingement on solids has exhibited some nonlinear effects not presented in collisions of individual atoms with those solids. The study of the secondary ion emissions can give insight into the energy deposition and relaxation steps of the clustersolid interaction. The dependence of the yields of secondary ion emission induced by clusters on the energy of clusters,cluster sizes,charge states and material structures of the targets was reviewed in this paper.
2005, 22(2): 198-199.
doi: 10.11804/NuclPhysRev.22.02.198
Abstract:
The responses of two extended neutron rein counters as function of neutron energy was ca1cuated Monte Carlo code，MCNPx，was applied in the calculations．Isotropic neutron incidence was employed．The results show that the neutron response is independent on thickness of lead 1aver at low energies，and it is clearly increased with thickness of lead layer at high energies．Although tt1e shape of the response curve does not completely agree with the H (10) curve in ICRP 74 report ，the resuhs obtained give good bases for the practical use of the new instrument in high—energy neutron fields
The responses of two extended neutron rein counters as function of neutron energy was ca1cuated Monte Carlo code，MCNPx，was applied in the calculations．Isotropic neutron incidence was employed．The results show that the neutron response is independent on thickness of lead 1aver at low energies，and it is clearly increased with thickness of lead layer at high energies．Although tt1e shape of the response curve does not completely agree with the H (10) curve in ICRP 74 report ，the resuhs obtained give good bases for the practical use of the new instrument in high—energy neutron fields
2005, 22(2): 200-203.
doi: 10.11804/NuclPhysRev.22.02.200
Abstract:
This paper reports hot electron energy spectrum measured with electron spectrometer, and Optical Transition Radiation measured with optical timeintegrated image of CCD during the interaction of lasersolid target in targets at the rearside radiation of laser on 20 Terawatt femtosecond laser facility. It shows that hot electron energy spectrum can be fitted with twotemperature likeMaxwellian distribution, with T≈90 and 280 keV,but average temperature of hot electrons T≈185 keV, which accorded with the known temperature scaling law. Because Optical Transition Radiation is produced by the hot electrons transport through solid targets, region of Optical Transition Radiation has lager radiation angle and optical intensity distribution. The main acceleration of hot electron comes from resonance absorption.
This paper reports hot electron energy spectrum measured with electron spectrometer, and Optical Transition Radiation measured with optical timeintegrated image of CCD during the interaction of lasersolid target in targets at the rearside radiation of laser on 20 Terawatt femtosecond laser facility. It shows that hot electron energy spectrum can be fitted with twotemperature likeMaxwellian distribution, with T≈90 and 280 keV,but average temperature of hot electrons T≈185 keV, which accorded with the known temperature scaling law. Because Optical Transition Radiation is produced by the hot electrons transport through solid targets, region of Optical Transition Radiation has lager radiation angle and optical intensity distribution. The main acceleration of hot electron comes from resonance absorption.
2005, 22(2): 204-207.
doi: 10.11804/NuclPhysRev.22.02.204
Abstract:
DNA is considered to be the most important and sensitive target in biological systems. In addition to the base damage, DNA strand breaks are the major lesion in the genome due to exposure to ionizing radiation. Mutation can be introduced to DNA as a result of enzymatic processing of DNA lesions or postirradiation replication. However, the mechanisms of radiationinduced mutations are not well clarified at the molecular level. To study the effect on the simple plasmid DNA of heavy ion is even predominant or more feasible.
Plasmid pUC18 DNA was prepared and irradiated by neon beam (7.199 MeV/u). The fragment distributions were determined by quantifying the ethidium bromide fluorescence. It can be seen that the shape of the intensity distributions is vastly different for the used radiation Dose. The distribution produced shows an excess of fragments particularly in 3 000 and 10 000 Gy the size range between 20—40 kbp and 20—50 bp. This clustering of doublestranded fragments might be influenced by the higher order chromatin structure of genomic DNA. If so, DNA loop structures could correspond to the size range for which we observed DSB clustering. Further studies aim at elucidating the heterogeneity of DSB induction within the genome and investigate the influence of chromatin structure on the nonrandom fragment distribution.
DNA is considered to be the most important and sensitive target in biological systems. In addition to the base damage, DNA strand breaks are the major lesion in the genome due to exposure to ionizing radiation. Mutation can be introduced to DNA as a result of enzymatic processing of DNA lesions or postirradiation replication. However, the mechanisms of radiationinduced mutations are not well clarified at the molecular level. To study the effect on the simple plasmid DNA of heavy ion is even predominant or more feasible.
Plasmid pUC18 DNA was prepared and irradiated by neon beam (7.199 MeV/u). The fragment distributions were determined by quantifying the ethidium bromide fluorescence. It can be seen that the shape of the intensity distributions is vastly different for the used radiation Dose. The distribution produced shows an excess of fragments particularly in 3 000 and 10 000 Gy the size range between 20—40 kbp and 20—50 bp. This clustering of doublestranded fragments might be influenced by the higher order chromatin structure of genomic DNA. If so, DNA loop structures could correspond to the size range for which we observed DSB clustering. Further studies aim at elucidating the heterogeneity of DSB induction within the genome and investigate the influence of chromatin structure on the nonrandom fragment distribution.
2005, 22(2): 208-211.
doi: 10.11804/NuclPhysRev.22.02.208
Abstract:
The low-dose responses such as hypersensitivity and increased radio-resistance of human hepatoma SMMC-7721 cells were studied in this work. Exponentially growing SMMC-7721 cells were irradiated with ~(60)Co γ-rays at doses of 0—6 Gy. Together with flow cytometer for precise cell sorting, cell survival fractions were measured by means of conventional colony-formation assay. It has been found that the SMMC-7721 cells showed hyper-radiosensitivity response at low doses and increased radio-resistance at larger
The low-dose responses such as hypersensitivity and increased radio-resistance of human hepatoma SMMC-7721 cells were studied in this work. Exponentially growing SMMC-7721 cells were irradiated with ~(60)Co γ-rays at doses of 0—6 Gy. Together with flow cytometer for precise cell sorting, cell survival fractions were measured by means of conventional colony-formation assay. It has been found that the SMMC-7721 cells showed hyper-radiosensitivity response at low doses and increased radio-resistance at larger
2005, 22(2): 212-215.
doi: 10.11804/NuclPhysRev.22.02.212
Abstract:
We investigate the radiation response of hepatoma cells SMMC-7721 by premature chromosome condensation (PCC) technique. A dose-dependent increase in radiation-induced chromatid/isochromatid breaks was observed in G1 and G2 phase respectively. A good relationship was found between cell survival and chromatin breaks.
We investigate the radiation response of hepatoma cells SMMC-7721 by premature chromosome condensation (PCC) technique. A dose-dependent increase in radiation-induced chromatid/isochromatid breaks was observed in G1 and G2 phase respectively. A good relationship was found between cell survival and chromatin breaks.
2005, 22(2): 216-218.
doi: 10.11804/NuclPhysRev.22.02.216
Abstract:
Human hepatoma cells hep G2 were irradiated with 3 Gy of γray 8 hours after primed with 0.05 Gy of γray， thereafter，cell survival and cell cycle were determined. The results indicated that both survival adaptive response and the enhanced ability to overcome G2/M arrest could be induced by preirradiation with low dose of γray. It is suggested that there is a certain correlation between the survival adaptive response and the enhanced ability to overcome cell cycle arrest.
Human hepatoma cells hep G2 were irradiated with 3 Gy of γray 8 hours after primed with 0.05 Gy of γray， thereafter，cell survival and cell cycle were determined. The results indicated that both survival adaptive response and the enhanced ability to overcome G2/M arrest could be induced by preirradiation with low dose of γray. It is suggested that there is a certain correlation between the survival adaptive response and the enhanced ability to overcome cell cycle arrest.
2005, 22(2): 219-224.
doi: 10.11804/NuclPhysRev.22.02.219
Abstract:
Although tumor gene therapy has a distance to clinical use due to some problems, the combination of irradiation and gene therapy holds much promise in cancer therapy based on the traditional radiotherapy, chemotherapy and surgery. We have termed this therapeutic radiogenic therapy. This review focuses on the group of radiogenic therapy that are either： ⑴ improvement of gene transfer efficiency by irradiation; ⑵ radiotherapy combined with cytokines gene delivery or enhancement of the immunity of tumor cells by transgene; ⑶ directly stimulated by radiation to produce either directly or indirectly cytotoxic agents; ⑷ increasing of radiosensitivity in gene therapy; ⑸ radioprotective gene therapyenhances radiation tumor killing effect while protecting the normal tissue and organs with transgene using transfer vector.
Although tumor gene therapy has a distance to clinical use due to some problems, the combination of irradiation and gene therapy holds much promise in cancer therapy based on the traditional radiotherapy, chemotherapy and surgery. We have termed this therapeutic radiogenic therapy. This review focuses on the group of radiogenic therapy that are either： ⑴ improvement of gene transfer efficiency by irradiation; ⑵ radiotherapy combined with cytokines gene delivery or enhancement of the immunity of tumor cells by transgene; ⑶ directly stimulated by radiation to produce either directly or indirectly cytotoxic agents; ⑷ increasing of radiosensitivity in gene therapy; ⑸ radioprotective gene therapyenhances radiation tumor killing effect while protecting the normal tissue and organs with transgene using transfer vector.
2005, 22(2): 225-228.
doi: 10.11804/NuclPhysRev.22.02.225
Abstract:
DNA damage induced by irradiation，which makes the cell arrested at G1 stage and DNA repair being activated in this stage，are summarized. It is proposed that the deficiency of adenosine triphosphate which is induced by the larger irradiation dose, induces cell apoptosis. And the relationship of cell selecting repair and apoptosis is also analyzed.
DNA damage induced by irradiation，which makes the cell arrested at G1 stage and DNA repair being activated in this stage，are summarized. It is proposed that the deficiency of adenosine triphosphate which is induced by the larger irradiation dose, induces cell apoptosis. And the relationship of cell selecting repair and apoptosis is also analyzed.
2005, 22(2): 229-232.
doi: 10.11804/NuclPhysRev.22.02.229
Abstract:
Apoptin is an anticancer gene. It can induce p53independent，Bcl2insensitive type of apoptosis in various human tumor cells，and fails to induce programmed cell death in normal cell. Because of having tumor specificity， apoptin can be transferred enough to tumorcell in vivo，selectly kill the tumor as a potential antitumor biological preparation. In this paper， we provide a brief review on the anticancer mechanism of apoptin， current status and application prospect， and the main issues in apoptin studies.
Apoptin is an anticancer gene. It can induce p53independent，Bcl2insensitive type of apoptosis in various human tumor cells，and fails to induce programmed cell death in normal cell. Because of having tumor specificity， apoptin can be transferred enough to tumorcell in vivo，selectly kill the tumor as a potential antitumor biological preparation. In this paper， we provide a brief review on the anticancer mechanism of apoptin， current status and application prospect， and the main issues in apoptin studies.
甘公网安备 62010202000723号