High-efficiency transfer and expression of AdCMV-p53 in human cervix adenocarcinoma cells induced by subclinical-dose carbon beam radiation

Purpose The aim of this study is to evaluate the eVect of carbon-beam irradiation on adenovirus-mediated p53 transfer in human cervix adenocarcinoma.Materials and methods The HeLa cells pre-exposed to carbon-beam or -ray, were infected with replication-deficient adenovirus recombinant vectors, containing human wild-type p53 (AdCMV-p53) and green Xuorescent protein (GFP) (AdCMV–GFP), respectively. The GFP transfer and p53 expression were detected by Xow cytometric analysis.Results The GFP transfer frequency in C-beam with AdCMV-GFP groups was 38–50% more than that inγ-ray with AdCMV–GFP groups. The percentage of p53 positive cells in the C-beam with AdCMV–p53 groups was 34–55.6% more than that in γ-ray with AdCMV-p53 groups (p < 0.05), suggesting that subclinical-dose C-beam irradiation could signiWcantly promote exogenous p53 transfer and p53 expression, and extend the duration of p53 expression in the HeLa cells. The expression of p21 increased with p53 expression in HeLa cells. The survival fractions for the 0.5–1.0 Gy C-beam with AdCMV-p53 groups were 38–43% less than those for the isodose γ-ray with AdCMV-p53 groups, and 31–40% less than those for the C-beam only groups (p <0.05).Conclusions The subclinical-dose C-beam irradiation could signiWcantly promote the transfer and expression of exogenous p53, extend the duration of p53 expression, and enhance the suppression of p53 on cervix adenocarcinoma cells.

Simulation of the Lanzhou Penning Trap LPT

The LPT (Lanzhou Penning Trap) is under construction and its task is to perforin direct mass measurement of fusion-evaporation residue, and if possible for heavy isotopes. Detailed simulations have been clone for a good understanding to the ion's movement and mechanics in the trap. The optimizal ion of the LPT is also performed based on the simulation. With a scale of 0.5 mm per grid used in the, simulation and many other limitations a highest mass resolution has been achieved to be 1.9 x 10(-5). An unexpected behavioin in the simulation related to magnetron motion has been found.

Efficiency calibration of neutron detector array for beta decay of exotic nuclei

The research of the in-beam efficiency calibration of Neutron Detector Array of Peking University using N-17 and C-16 beams was introduced in this paper. The efficiency of neutron wall and ball are comparable to the foreign similar devices and neutrons can be detected from low to high energies in high efficiency.

Study of buncher efficiency in axial injection system of SFC

In order to reduce the influence of the stray electric field of the buncher in the axial injection system of SFC and to improve the injection efficiency of SFC, the existing buncher electrode is investigated and a new electrode is designed. The influences of the electric field to the beams for the both cases are simulated. The simulation results show that the bunching efficiency is improved from 55% to 74% with the new electrode. At the same time, the influence of the space charge is computed and according to the results, the location of the buncher is readjusted too.

High-efficiency transfer and expression of AdCMV-p53 in human hepatocellular carcinoma cells induced by low-dose carbon-ion radiation

Objective To investigate whether the irradiation with C-beam could enhance adenovirus-mediated transfer and expression of p53 in human hepatocellular carcinoma. Materials and methods HepG2 cells were exposed to C-beam or gamma-ray and then infected with replicationdeficient adenovirus recombinant vectors containing human wild-type p53 or green fluorescent protein, respectively. The transfer efficiency and expression level of the exogenous gene were detected by flow cytometric analysis. Cell survival fraction was detected by clonogenic assay. Results The transfer frequency in C-beam or gamma-irradiated groups increased by 50-83% and 5.7-38.0% compared with the control, respectively (P < 0.05). Compared with C-beam alone, p53 alone, and gamma-ray with p53, the percentages of p53 positive cells for 1 Gy C-beam with p53 increased by 56.0-72.0%, 63.5-82.0%, and 31.3-72.5% on first and third day after the treatments, respectively (P < 0.05). The survival fractions for the 2Gy C-bearn and AdCMV-p53 infection groups decreased to similar to 2%. Conclusion C-beam irradiation could significantly promote AdCMV-green fluorescent protein transfer and expression of p53.

分离扇回旋加速器的接受度及效率；Acceptance and efficiency of sector-separated cyclotron

以9.7MeV/u的238U36+,5.62MeV/u的70Zn10+为典型离子,分析并模拟了分离扇回旋加速器(SSC)的注入、加速和引出,得到了SSC在理论等时场下横向和纵向的接受度。为了研究SSC在实际情况下的接受度,在实测场的基础上采用Kr-Kb方法以及Lagrange插值方法建立了与实际比较符合的等时场,计算了该等时场下SSC横向和纵向的接受度,发现了导致SSC实际接受度和传输效率低的主要原因在于注入系统中的MSI3元件和引出系统中的MSE3元件设计存在缺陷。模拟结果显示,通过改变MSI3和MSE3的曲率或者垫铁改变元件内部的场分布可以改善SSC的实际接受度和传输效率。

Penning trap mass measurements on nobelium isotopes

The Penning trap mass spectrometer SHIPTRAP at GSI Darmstadt allows accurate mass measurements of radionuclides, produced in fusion-evaporation reactions and separated by the velocity filter SHIP from the primary beam. Recently, the masses of the three nobelium isotopes No252-254 were determined. These are the first direct mass measurements of transuranium elements, which provide new anchor points in this region. The heavy nuclides were produced in cold-fusion reactions by irradiating a PbS target with a Ca-48 beam, resulting in production rates of the nuclei of interest of about one atom per second. In combination with data from decay spectroscopy our results are used to perform a new atomic-mass evaluation in this region.

Efficiency Dynamics on Two Coupled Small-World Networks

We investigate the effect of clusters in complex networks on efficiency dynamics by studying a simple efficiency model in two coupled small-world networks. It is shown that the critical network randomness corresponding to transition from a stagnant phase to a growing one decreases to zero as the connection strength of clusters increases. It is also shown for fixed randomness that the state of clusters transits from a stagnant phase to a growing one as the connection strength of clusters increases. This work can be useful for understanding the critical transition appearing in many dynamic processes on the cluster networks.

Optimal design of a 7 T highly homogeneous superconducting magnet for a Penning trap

A Penning trap system called Lanzhou Penning Trap (LPT) is now being developed for precise mass measurements at the Institute of Modern Physics (IMP). One of the key components is a 7 T actively shielded superconducting magnet with a clear warm bore of 156 mm. The required field homogeneity is 3 x 10(-7) over two 1 cubic centimeter volumes lying 220 mm apart along the magnet axis. We introduce a two-step method which combines linear programming and a nonlinear optimization algorithm for designing the multi-section superconducting magnet. This method is fast and flexible for handling arbitrary shaped homogeneous volumes and coils. With the help of this method an optimal design for the LPT superconducting magnet has been obtained.

EFFICIENCY DYNAMICS ON SCALE-FREE NETWORKS WITH COMMUNITIES

The simple efficiency model is developed on scale-free networks with communities to study the effect of the communities in complex networks on efficiency dynamics. For some parameters, we found that the state of system will transit from a stagnant phase to a growing phase as the strength of community decreases.

Design of a 7 T Superconducting Magnet for Lanzhou Penning Trap

A penning trap system called LPT (LANZHOU PENNING TRAP) is now being developed for precise mass measurements in IMP (Institute of Modern Physics). The most key component of LPT is a superconducting magnet. A Phi 156 mm warm bore and two cylinder good field regions with a distance of 220 mm are required for trapping ions and measurements. As the required homogeneity is better than 0.5 ppm, several complicated coaxial coils are used to produce such a magnetic field. The size and position of these coils are optimized by using a method combining linear program with multiobjective optimization. Superconducting shim coils and passive shim pieces are used to eliminate inevitable winding tolerances and environmental influence. The fringe field is decreased to 5 Gs at 2 m line from the center of the magnet by active shielding coils. The designs of the mechanical structure, the quench protection system are also introduced in this paper.