Vol.17,

Shanghai Synchrotron Radiation Facility (SSRF), one of the third generation light sources, aims to produce high brightness and/or high flux X-ray source for users; therefore insertion devices (IDs) are important magnetic elements for SSRF. In this paper, the linear perturbations due to IDs toward its storage ring lattice, such as beta function distortions, tune shifts, emittance growths, and energy spreads are estimated by using analytical formulae, and the nonlinear effects from IDs, especially dynamic aperture, are simulated by using Racetrack code. The results show that (a) the reduction of dynamic aperture from single undulator is negligible, since electron beam energy of 3.5 GeV is high and ID's magnetic field is low, and the beta functions in the middle of straight sections, where ID is located, are well optimized; (b) however, the reduction from single wigglers, especially super-conducting wiggler, is visible, because of its higher magnetic field; (c) effects of each ID on emittance growths and energy spreads are less than 7%.

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One design of multi-function LIGA beamline has been reported. In this design, two plane mirrors and a series of filters have been employed. One can choose the spectrum range of X-ray easily according to the exposure requirement by adjusting the grazing angle of mirrors and the thickness of filters. And the spot size in the horizontal direction is up to 120mm, which is large enough for exposing 5 inch silicon slice. The typical exposure time is about 1.2h, 1.8h, 0.5h, corresponding to PMMA thickness of 500μm, 200μm, 20μm, respectively.

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Compared with bulk-silicon technology, silicon-on-insulator (SOI) technology possesses many advantages but it is inevitable that the buried silicon dioxide layer also thermally insulates the metal–oxide–silicon field-effect transistors (MOSFETs) from the bulk due to the low thermal conductivity. One of the alternative insulator to replace the buried oxide layer is aluminum nitride (AlN), which has a thermal conductivity that is about 200 times higher than that of SiO₂ (320 W·m⁻¹·K⁻¹ versus 1.4 W·m⁻¹·K⁻¹). To investigate the self-heating effects of small-size MOSFETs fabricated on silicon-on-aluminum nitride (SOAN) substrate, a two-dimensional numerical analysis is performed by using a device simulator called MEDICI run on a Solaris workstation to simulate the electrical characteristics and temperature distribution by comparing with those of bulk and standard SOI MOSFETs. Our study suggests that AlN is a suitable alternative to silicon dioxide as a buried dielectric in SOI and expands the applications of SOI to high temperature conditions.

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In this paper, we simulate γ-ray energy deposition for different incident energies with four different models using the tool GEANT4 (Geant4.7.0, 2005) developed by CERN (the Center of European Research of Nucleus). The results we obtained indicate that there are different peak values for different incident energies. That is, we can differentiate the incident energy accurately if the detector can determine the peak value accurately. This is meaningful for the geometrical configuration of the detector to get the most probable distribution (MPD) of energy deposition for different incident energies. According to the simulation, we can insert certain slices with large absorption coefficient to obtain a better MPD of energy deposition which will not alter the shape of the energy deposition.

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The synthesis and biological evaluation of serotonin (5-HT_1A) imaging agent [¹³¹I]- 4-iodo-N-{2-[4-(2-methoxyphenyl)-piperazin-1-yl]-ethyl}-N-pridin-2-yl-benzamide ([¹³¹I]MPPI ) are reported. The chemical structure of aimed compound and intermediates were confirmed by IR, ¹HNMR, and MS. Radiochemical purity was above 99% determined by TLC. Biodistribution of [¹³¹I]MPPI in rats displayed high uptake in hippocampus and low uptake in cerebellum. The ratio of the uptake of [¹³¹I]MPPI in hippocampus to that in cerebellum was 2.90 at 30 min post injection. The radioactivity in thyroid was 0.069 and 0.128% ID/g organ at 5 min and 120 min, respectively, and it was increased with time, which suggests that in vivo deiodination may be the major route of metabolism. Ex vivo autoradiography of brain section displayed significant decrease of radioactivity in hippocampus when pretreated with 8-OH-DPAT, a selective 5HT_1A agonist, compared with control. These findings strongly suggested that ¹³¹I-MPPI could be used as an in vivo marker for studies of pharmacology of the 5-HT_1A receptor system in animals.

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The weight loss in vivo degradation of poly (lactide-co-glycolide) (PLGA) radiolabeled with ¹²⁵I was investigated. PLGA with molecular weight (M_w) of 84000(LA/GA=85/15) were labeled with ¹²⁵I in the chloroform media by circularly heating and round films of about 15mm in diameter were formed. The composition and M_w of the ¹²⁵I-PLGA were characterized by ¹H-NMR and viscosimeter. The weight loss of this copolymer in vitro and in vivo degradation was quantified by determining radioactivity of materials. The results indicated that PLGA exhibited significantly faster degradation in vivo than that of in vitro conditions.

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Sodium-concrete interaction is a key safety-related issue in safety analysis of liquid metal cooled fast breeder reactors (LMFBRs). The chemical kinetics model is a key component of the sodium-concrete interaction model. Conservation equations integrated in sodium-concrete interaction model cannot be solved without a set of relationships that couple the equations together, and this may be done by the chemical kinetics model. Simultaneously, simulation of chemical kinetics is difficult due to complexity of the mechanism of chemical reactions between sodium and concrete. This paper describes the chemical kinetics simulation under some hypotheses. The chemical kinetics model was integrated with the conservation equations to form a computer code. Penetration depth, penetration rate, hydrogen flux, reaction heat, etc. can be provided by this code. Theoretical models and computational procedure were recounted in detail. Good agreements of an overall transient behavior were obtained in a series of sodium-concrete interaction experiment analysis. Comparison between analytical and experimental results showed that the chemical kinetics model presented in this paper was creditable and reasonable for simulating the sodium-concrete interactions.

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The steady-state characteristics of a two-phase natural circulation loop were investigated based on the homogenous model. Transcendental equations of non-dimensional loop mass flow rate under various conditions were also derived. The static bifurcation diagram of a two-phase natural circulation described with non-dimensional variables N_pch-m⁺ was obtained. In addition, various steady-state characteristics of a natural circulation loop were analyzed and discussed. These characteristics include the existence of multiple solutions under certain conditions, and the maximum mass flow rate. The authors also examined the effects of important parameters such as sub-cooling number, riser-to-heated-region length ratio, and riser-to-heated-region diameter ratio.

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