Vol.25,

We studied the role that electron gas has on the formation of nuclear structures at subsaturation densities and low temperatures (T < 1 MeV). Using a classical molecular dynamics model we studied isospin symmetric and asymmetric matter at subsaturation densities and low temperatures varying the Coulomb interaction strength. The effect of such variation was quantified on the fragment size multiplicity, the inter-particle distance, the isospin content of the clusters, the nucleon mobility and cluster persistence, and on the nuclear structure shapes. We found that the presence of an electron gas distributes matter more evenly, disrupts the formation of larger objects, reduces the isospin content, and modifies the nucleon average displacement, but does not affect the inter-nucleon distance in clusters. The nuclear structures are also found to change shapes by different degrees depending on their isospin content, temperature and density.

735

629

Beam position monitors (BPMs) have been widely used in all kinds of measurement systems, feedback systems and other areas in particle accelerator field these days. The malfunction of a single BPM can cause serious consequences such as the failure of the orbit feedback and the transverse feedback. A troubleshooting has been made to prevent the defective BPMs from affecting the accuracy and stability of the storage ring in Shanghai Synchrotron Radiation Facility (SSRF). Different types of malfunctions have been successfully identified by using the idea of principal component analysis (PCA).

794

The control system of SSRF (Shanghai Synchrotron Radiation Facility) is based on EPICS (Experimental Physics and Industrial Control System). Operation data storage for synchrotron radiation facility is important for its status monitoring and analysis. At SSRF, operation data used to be index files recorded by traditional EPICS Channel Archiver. Nevertheless, index files are not suitable for long-term maintenance and difficult for data analysis. Now, RDB Channel Archiver and MySQL are used for SSRF beamline operation data archiving, so as to promote the data storage reliability and usability. By applying a new uploading mechanism to RDB Channel Archiver, its writing performance is improved. A web-based GUI (Graphics User Interface) is also developed to make it easier to access database.

694

Considering the mixture after muon-catalyzed fusion (μCF) reaction as overdense plasma, we analyze muon motion in the plasma induced by a linearly polarized two-colour laser, particularly, the effect of laser parameters on the muon momentum and trajectory. The results show that muon drift along the propagation of laser and oscillation perpendicular to the propagation remain after the end of the laser pulse. Under appropriate parameters, muon can go from the skin layer into field-free matter in a time period of much less than the pulse duration. The electric-field strength ratio or frequency ratio of the fundamental to the harmonic has more influence on muon oscillation. The laser affects little on other particles in the plasma. Hence, in theory, this work can avoid muon sticking to α effectively and reduce muon-loss probability in μCF.

516

Radiation-induced lung injury is one of the main dose limiting factors for thoracic radiation therapy. Gelsolin (GSN) is a widespread, multifunctional regulator of cellular structure and metabolism. In this work, the roles of GSN in radiation-induced lung injury in Balb/c mice were studied. The GSN levels in plasma reduced progressively in 72 hours after irradiation, and then increased gradually. GSN contents in the bronchoalveolar lavage (BAL) fluid increased after thoracic irradiation, whereas mRNA levels of GSN in the lung tissue decreased significantly within 24 hours after irradiation and then increased again. Mice were intravenously injected with 50 μg GSN antibody 0.5 hour before 20 Gy of thoracic irradiation. GSN antibody pretreatment increased lung inflammation, protein concentration in the BAL fluid and leukocytes infiltration in the irradiated mice. The activities of superoxidase dismutase (SOD) in the plasma and the BAL fluid in irradiated mice injected with GSN antibody were less than that of control groups, whereas the levels of malondialdehyde (MDA) increased. These results suggest that pretreatment of GSN antibody may aggravate radiation-induced pneumonitis.

614

In this study, strains of Aspergillus niger 4# for hyper citric acid were irradiated to different doses by 80 MeV/u ¹²C⁶⁺ ion beams. Seven mutant strains showed marked citric acid over-production records and faster productivity than initial Aspergillus niger 4# by shaking flash fermentation. The maximum product yield was 132.8 -g L^-1( the H4002 strain) being a 8.8% increase to the initial strain. The scale-up experiment was carried out in a 100 L bioreactor. The mutant H4002 can accumulate 187 -g L^-1 product yield of citric acid from starch liquefying supernatant. The productivity of citric acid was 2.75 g L^-1 h^-1. So, the mutant H4002 possesses rapid sugar katabolism for producing citric acid. Meanwhile, the pellet morphology kept compact and round during the whole submerged fermentation, which was suited to produce citric acid. The results indicate that mutant H4002 has potential ability to produce citric acid rapidly.

639

Elemental analyzer/isotope ratio mass spectrometry (EA/IRMS) has been widely applied to analyze the ¹⁵N/¹⁴N isotope composition (δ¹⁵N) of plants and soils, but the δ¹⁵N results may be inaccurate due to incomplete combustion of the high-C/N-ratio plant samples by EA. Therefore, it is necessary to develop a method to solve the problem of imperfect combustion. In this study, we used two methods: 1) adding copper oxide powder to the samples, and 2) increasing the O₂ flow (from 100 mL min^-1 to 200 mL min^-1) for the auto sampler inlet purge line of the EA. The δ¹⁵N values of the plant samples became more positive and tended to be stable after complete combustion. Also, the required blank samples for each plant sample decreased with increasing amount of the added CuO powder. However, at 200 mL min^-1 of the oxygen flow in the EA, complete combustion could not be achieved without adding copper oxide, but this was done with decreased amount of CuO powder. Therefore, mixing cupric oxide into the high-C/N-ratio samples was an efficient, simple and convenient way to solve the problem of imperfect combustion in the EA.

851

To detect the prognostic significance of interim ¹⁸F-FDG PET/CT SUV (standard uptake value) reduction (ΔSUV_max) associated with Ki67 in patients with diffuse large B cell lymphoma (DLBCL). 47 DLBCL patients underwent PET/CT before initiation and after 2–4 cycles of chemotherapy were included. The SUV_max of the dominant lesions were calculated. Ki67 positive indices were provided by enzyme-labeled immuno-histochemistry. SPSS17.0 was used for statistical analysis. ΔSUV_max of different groups were compared by t test. Receiver-operator characteristic analysis was performed to determine the optimal cutoff values. Kaplan-Meier analyses of PFS (Progression-free survival) were compared using log-rank test. The average of ΔSUV_max and ΔSUV_max% were 11.53 and 69.10%, respectively. The optimal cutoff values of ΔSUV_max and ΔSUV_max% were 11.45 and 82.92%, respectively. Higher ΔSUV_max and ΔSUV_max% indicated longer PFS (p<0.001). The optimal cutoff value of Ki67 was 55%. Ki67≥55% was revealed to be an indicator of shorter PFS (p=0.019). Either ΔSUV_max≤11.45 or Ki67>55% was defined as an indicator to poor outcome and scored 1 point. The PFS rate was 100% in patients scored 0 point, yet 0% in patients scored 2 points. PFS tended to be shorter along with the score getting higher (p=0.006). ΔSUV_max and Ki67 positive index were both of significance in DLBCL prognosis. The prognostic value may be confirmed when ΔSUV_max was accordant with Ki67.

497

Sweet sorghum has the potential of becoming a useful energy crop. An early-maturity mutant of sweet sorghum, KFJT-1, was obtained by carbon ions irradiation of KFJT-CK, a wild plant. In this paper, we evaluate the mutant from the length and fresh weight of radicle and leaves after seed germination, the growth rate at the elongation stage, and the internodal parameters under field trail condition. The results showed that the seedling growth of KFJT-1 was inhibited by carbon ions irradiation, and the leaf length, the fresh weight of radicle and leaves from KFJT-1 decreased by 15.32%, 76.27%, and 27.08% than those of KFJT-CK, respectively. However, the growth rate of KFJT-1 on July 12, July 27 and August 1 increased by 16.19%, 59.28% and 26.87%, respectively, compared with the KFJT-CK. The stalk diameter, total biomass yield and sugar content of KFJT-1 was higher than those of KFJT-CK, despite that the plant height of KFJT-1 was significantly less than KFJT-CK (P<0.05). In addition, KFJT-1 differed from KFJT-CK in the internodal length, weight and sugar content. In conclusion, the early-maturity mutant of KFJT-1 will be a promising variety for sweet sorghum industrialization in Gansu province, China.

519

Three kinds of amphiphilic PMADAB gels were prepared through radiation-induced polymerization and crosslinking of methacryloxyethyl dimethylalkane ammonium bromide (MADAB) with different alkyl side chains (butyl, octyl and dodecyl). The length of alkyl side chains had significant influence on swelling behavior of the PMADAB gels in alcohol/water solvent. Equilibrium swelling degree (EDS) of PMBDAB (butyl) gel in water was ca. 160 and decreased with increasing alcohol content (x), whereas EDS of PMODAB (octyl) and PMDDDAB (dodecyl) gels showed a convex-upward function of x, i.e., these two gels barely swelled in pure water and swelled with increasing x and then shrank gradually. This phenomenon was explained by the hydrophobic association of long alkyl chains and a cosolvency effect of PMADAB in alcohol and water. The swelling behavior of PMADAB gels in methanol, ethanol and isopropanol were similar, and their EDS are related with the dielectric constant of alcohol solvents. The results suggest that PMADAB gels may be potential absorbents for various kinds of alcohols.

516

Beam current dependence resulted from nonlinearity and asymmetry of the four channels of digital BPM (Beam Position Monitor) processor deteriorates the BPM performance. A systematic solution based on signal source calibration tactics has been carried out to rectify this defect. It is optimized for implementation in FPGA. Mathematical illustrations of the calibration method, hardware and software design and implementation are presented. A signal source circuit using frequency synthesis technique is designed as calibration standard. Data acquisition system using JAVA web technology and Ethernet is introduced. Integrated FPGA implementation code architecture is presented, and experimental test results show that the method implemented in FPGA is feasible. Compared to other methods, our approach can rectify the nonlinearity and asymmetry simultaneously. The whole solution is integrated into the DBPM processor and can be executed online.

691

Resistive Plate Chambers (RPCs) built from a new type of Bakelite developed at Institute of High Energy Physics (IHEP), Chinese Academy of Sciences have been used in the BESIII Muon identification system for several years without linseed oil coating, but characteristic aging performances were observed. To adapt to the RPCs in the aging state, the front-end electronics have been upgraded by enhancing the front-end protection, improving the threshold setting circuit, and separating power supplies of the comparator and the field programmable gate array (FPGA). Improvements in system stability, front-end protection and threshold consistency have been achieved. In this paper, the system upgrade and the test results are described in detail.

780

767

The ambiguity of the structure of ¹²Be especially in the configuration of ¹²Be ground state has attracted a lot of attention recently. We notice that the nuclear reaction cross section σ_R at low energy region is sensitive to the surface structure of ¹²Be, which is greatly impacted by the ground state configuration of ¹²Be especially by the occupancy probability of the s orbital component. By using existed interaction cross section data of ¹²Be on C at 790 MeV/nucleon and Glauber model, the upper limit of the s orbital occupation probability of ¹²Be ground state is roughly determined to be about 56% with Single Particle Model calculations. This demonstrates that the method is very promising to determine the s orbital component of ¹²Be with proper nuclear-matter density distribution calculations for different orbitals of ¹²Be ground state. Hence we bring forward to determine the s orbital component of ¹²Be by measuring the σ_R of ¹²Be on C and Al at several tens of MeV/nucleon. In this paper, the feasibility and detailed experimental scheme of the σ_R measurement are carefully studied. The precision of the s orbital occupation probability of ¹²Be ground state is expected to achieve 9% by using the proposed 2% σ_R data.

565

The molecular behaviors of interfacial water molecules at the solid/liquid interface are of a fundamental significance in a diverse set of technical and scientific contexts, thus have drawn extensive attentions. On certain surfaces, the water monolayer may exhibit an ordered feature, which may result in the novel wetting phenomenon. In this article, based on the molecular dynamics simulations, we make a detailed structure analysis of the ordered water monolayer on ionic model surface with graphene-like hexagonal lattices under various charges and unit cell sizes. We carefully analyze the water density profiles and potential of mean force, which are the origin of the special hexagonal ordered water structures near the solid surface. The number of hydrogen bonds of the ordered water monolayer near the solid surface is carefully investigated.

845

An accurate and fast sampling method was developed on the modeling of a voxel phantom called Rad-HUMAN for radiation protection of MC-based radiation transport and simulation. The segmented organ voxels, which were assigned with three dimensional (3D) coordinates, were simplified through a two-step hybrid sampling algorithm. Firstly, certain voxels were sampled into a coordinate matrix by the nearest neighbor sampling. Secondly, the coordinate matrix was renewed using a weighted sampling. To compare visualization with the sampling, the resultant matrix was used to extract the contour of organs/tissues for constructing polygon-surface phantom. The feasibility and effectiveness of the sampling method was verified through the modeling of large organs (e.g. skeleton system) and application of transformation to MC computational geometries.

494

Molten salt reactor (MSR) is a potential nuclear power reactor of Generation IV. The working process of the primary loop of an MSR is studied in this paper. A physical model is established to describe the coupled heat transfer for the MSR core channels, the temperature negative feedback and the neutron characteristics. The simulation code, NDP1D, has been developed with the object-oriented method, conducting the neutron diffusion and transient analysis in a parallel way. The simulation data and diagrams of neutron, power, flow rate and temperature can be obtained via graphical user interface. The simulation results can be used for further study on MSRs of larger dimensions and more complicated geometry.

974

In this work, we developed a numerical analysis-associated experiment method to determine the effective multiplication factor k_eff, which is difficult to obtain directly from conventional neutron source multiplication (NSM) method. The method is based on the relationship between k_eff, subcritical multiplication factor k_s and external neutron source efficiency Φ^∗ in the subcritical system. On basis of the theoretical analysis, the dependence of k_s and Φ^∗ on subcriticality and source position was investigated at the Chinese Fast Burst Reactor-II (CFBR-II). A series of k_s were measured by NSM experiments at four subcritical states (k_eff = 0.996; 0.994; 0.991; 0.986) with the ²⁵²Cf neutron source located at different positions (from the system center to outside) at each subcritical states. The Φ^∗ was obtained by Monte-Carlo simulation for each condition. With the measured k_s and calculated Φ^∗, k_eff of the subcritical system was evaluated with a relative difference of <1% between values obtained by the improved method and by positive period method. Especially, the relative difference of <0.18% with the source located at the system center.

499