Vol.20,

A fast orbit feedback system is designed at SSRF to suppress beam orbit disturbance within sub-micron in the bandwidth up to 100 Hz. The SVD (Singular value decomposition) algorithm is applied to calculate the inverse response matrix in global orbit correction. The number of singular eigenvalues will influence orbit noise suppression and corrector strengths. The method to choose singular eigenvalue rejection threshold is studied in this paper, and the simulation and experiment results are also presented.

453

In this paper we report the design and realization of beam trip diagnostic system at Shanghai Synchrotron Radiation Facility (SSRF). The system can find out the first fault signal in the key operation signals related to the RF system by analyzing the time sequence, also it can decide which trips occurs first among the three superconducting RF stations. All the states of monitored signals in a time period ahead and behind beam trip are recorded. The results are compared with those from other diagnostic tools at SSRF. The work is of help in improving reliability of the superconducting RF system and stability of the storage ring operation.

550

The optical and electrical properties of several composites, formed by filling the high density polyethylene (HDPE) with similar amount of carbon black (CB), multi-walled carbon nanotubes (MWNT) and fullerene (C₆₀), respectively, were characterized using a THz-TDS setup. It was found that the optical parameters and the details of their variation with frequency differ significantly for different kinds of carbon materials. The results are analyzed by using Cole-Cole formula of dipole relaxation under the assumption that carbon particles dispersed in the matrix behave like dipoles and contribute mainly to the dielectric loss in the THz frequency range. Fitting results indicate that MWNT and CB filled composites have a broader distribution of the relaxation time compared with C₆₀ which possesses a nearly single relaxation time. Compared with CB and C₆₀, MWNT filled composite possesses the larger relaxation strength due to its higher electron density and larger conductive clusters. The real part of conductivity for three kinds of composites all follows power law behavior with respect to frequency but the exponents are quite different. These phenomena may be related to the special properties of the fillers as well as their particulate structures, such as aspect ratio, particle size, and aggregate structure, etc.

502

Bacillus subtilis Bac01 was mutated by 15 keV N⁺ ions of 1.5×10¹⁶ cm^-2. The mutant strain Bac11 with high yield of endoglucanase was isolated using carboxymethylcellulose sodium and congo red indicative plates. It exhibited higher endoglucanase activitiy (381.89IU) than the original strain Bac01 (93.33IU). Two 1,500 bp endoglucanase gene fragments were obtained with PCR amplification from B. subtilis Bac01 and mutant strain Bac11. BLAST comparison result indicated that 10 nucleotides mutated. Bioinformatics methods were used to analyze the two predicted amino acid sequences, and it was found that 5 amino acid residues changed, being all in the cellulose-binding domain of endoglucanase.

461

A high current radio frequency quadrupole (RFQ) is being studied at the Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS) for the direct plasma injection scheme (DPIS). Because of the strong space charge of beams from laser ion source, the beam dynamics design of the RFQ has been carried out with a new code, which can deal with space charge effectively. The design of the RFQ structure is performed with an electromagnetic simulation code and the determination of parameters of the structure has been done to maximize the shunt impedance when the frequency is kept fixed. The influences of dipole mode effect and flatness on beams were also discussed.

573

This work is aim at studying the dependence of fission yields on incident neutron energy, so as to produce evaluated yield sets of the energy dependence. Experimental data at different neutron energies for gas fission products ^85m,87,88Kr and ¹³⁸Xe resulting from the ²³⁸U(n, f) reaction are processed using codes AVERAGE for weighed average and ZOTT for simultaneous evaluation. Energy dependence of the cumulative fission product yields on the incident neutron is presented. The evaluated curve of product yield is compared with the results calculated by the TALYS-0.64 code. The present evaluation is consistent with other main libraries in error permission. The fit curve of ^87,88Kr can be recommended to predict the unmeasured fission yields. Comparisons of the evaluated energy dependence curves with theoretical calculated results show that the predictions using purely theoretical model for the fission process are not sufficiently accurate and reliable for the calculations of the cumulative fission yields for the ²³⁸U(n,f).

444

Secretome, the totality of secreted proteins, is viewed as a promising pool of candidate cancer biomarkers. Simple and reliable methods for identifying secreted proteins are highly desired. We used an optimized semi-shotgun liquid chromatography followed by tandem mass spectrometry (LC-MS/MS) method to analyze the secretome of breast cancer cell line MDA-MB-231. A total of 464 proteins were identified. About 63% of the proteins were classified as secreted proteins, including many promising breast cancer biomarkers, which were thought to be correlated with tumorigenesis, tumor development and metastasis. These results suggest that the optimized method may be a powerful strategy for cell line secretome profiling, and can be used to find potential cancer biomarkers with great clinical significance.

629

In this paper, we describe a quantitative evaluation of the dosimetry effect of lack of side-scatter volume (LSSV). MapCheck, an integration diode array, was used to measure dose maps for three large non-IMRT fields (30cm ×30 cm and 40 cm×40 cm open fields, and 30 cm×30 cm wedge field with wedge angle of 60°) and 19 large IMRT fields. For each field, measurement was performed twice, under the conditions of (1) full scatter volume and (2) LSSV. Condition 1 was satisfied by adding PMMA slabs against the side of the MapCheck, and Condition 2, without PMMA slabs. The measured dose maps were compared with pass rate and their difference was scored when the acceptance criterion was set to 0.5%, 1%, 2%, 3%, etc. For very large open fields, the effect of LSSV may be clinically significant, while for large wedge fields and IMRT fields, the effect is negligible.

480

In this paper we analyze the results of dose map verifications for patient's IMRT (Intensity-modulated radiation therapy) plans and study the factors that may influence the accuracy of verification. MapCHECK, a two-dimensional diode array, was used to measure the dose maps for 1242 plans (14540 fields) from May 2004 to August 2008. The plans were designed with Pinnacle³ planning system. The passing rate of beams was determined when the acceptance criterion was 2%/2 mm, 3%/3 mm and 4%/4 mm. And the data with 3%/3 mm criteria was analyzed in more detail. The considered factors were beam modeling, optimization mode and treatment site. The median passing rate of total fields was 93.5%, 98.8%, and 100% when the acceptance criterion was 2%/2 mm, 3%/3 mm and 4%/4 mm, and the interquartile range were 11.1%, 3.8%, and 1.3%, respectively. The results of direct machine parameter optimization (DMPO) planning mode was better than those of multiple-step mode and beam modeling of new accelerators was better than that of old accelerators. These indicate that beam modeling is the key point of improving passing rate of IMRT verification and the influence of treatment site was little. The factors, the total number of segments, minimum area of segments and minimum monitor unit (MU) of segments, also influence the dosimetric accuracy of IMRT plan verification.

455

A novel zoledronic acid derivative, 1-hydroxy-2-(2-propyl-1H-imidazol-1-yl)ethane-1,1-diyldiphosphonic acid (PIDP), was synthesized by three-step reactions from 2-propyl-1H-imidazole. It was labeled with ⁹⁹Tc^m in conditions of 0.1 mg SnCl₂·2H₂O at pH 6.0 and ⁹⁹Tc^mO₄^- in aqueous solution for 20 min at room temperature. The labeling yield and radiochemical purity of ⁹⁹Tc^m-PIDP are both higher than 95%. The biodistribution results show that the bone uptake is up to 8.47%ID/g which is the maximum of bone uptake at 30 min after injection of ⁹⁹Tc^m-PIDP in mice. The pharmacokinetic parameters can be estimated from the exponential equation of C=59.565e^-11.307t + 2.069e^-1.211t. The clear bone image of rabbit was obtained at 120 min after injection of ⁹⁹Tc^m-PIDP. The results indicate that ⁹⁹Tc^m-PIDP has highly selective uptake in the skeletal and low uptake, rapid clearance in soft tissues, so it would be a potential novel bone imaging agent.

378

In order to achieve the auto-timing counts measurement of nuclear radiation using ORTEC 974 Counter/Timer, an auto-timing counts virtual instrument system based on the LabVIEW virtual instrument development platform and GPIB instrument control and transmission bus protocol is designed in this paper. By introducing software timing technique, the minimum time base of factory setting improves from 0.1 s to 0.03 s. The timing counts performance and longtime stability are also discussed in detail. The automatic data recording and saving facilitates data analysis and processing. Its real-time display and statistic function is very convenient for monitoring the nuclear radiation.

441

Effect of water injection on hydrogen generation during severe accident in a 1000 MWe pressurized water reactor was studied. The analyses were carried out with different water injection rates at different core damage stages. The core can be quenched and accident progression can be terminated by water injection at the time before cohesive core debris is formed at lower core region. Hydrogen generation rate decreases with water injection into the core at the peak core temperature of 1700 K, because the core is quenched and reflooded quickly. The water injection at the peak core temperature of 1900 K, the hydrogen generation rate increases at low injection rates of the water, as the core is quenched slowly and the core remains in uncovered condition at high temperatures for a longer time than the situation of high injection rate. At peak core temperature of 2100–2300 K, the Hydrogen generation rate increases by water injection because of the steam serving to the high temperature steam-starved core. Hydrogen generation rate increases significantly after water injection into the core at peak core temperature of 2500 K because of the steam serving to the relocating Zr-U-O mixture. Almost no hydrogen generation can be seen in base case after formation of the molten pool at the lower core region. However, hydrogen is generated if water is injected into the molten pool, because steam serves to the crust supporting the molten pool. Reactor coolant system (RCS) depressurization by opening power operated relief valves has important effect on hydrogen generation. Special attention should be paid to hydrogen generation enhancement caused by RCS depressurization.

493

The prompt supercritical process of a nuclear reactor with temperature feedback and initial power as well as heat transfer with a big step reactivity (ρ₀>β) is analyzed in this paper. Considering the effect of heat transfer on temperature of the reactor, a new model is set up. For any initial power, the variations of output power and reactivity with time are obtained by numerical method. The effects of the big inserted step reactivity and initial power on the prompt supercritical process are analyzed and discussed. It was found that the effect of heat transfer on the output power and reactivity can be neglected under any initial power, and the output power obtained by the adiabatic model is basically in accordance with that by the model of this paper, and the analytical solution can be adopted. The results provide a theoretical base for safety analysis and operation management of a power reactor.

463