[en] Recent experiments at USC have shown that two-dimensional films of ³He on graphite order ferromagnetically at finite temperatures (T>0) for densities above 20 atoms/nm². These results, obtained by measuring NMR on these films in the zero field limit, appear to contradict several studies which concluded that there is no spontaneous order by measuring magnetic susceptibility through conventional NMR in finite magnetic fields, and heat capacity in zero field. The low field limit is important in understanding these two-dimensional magnetic systems. At higher temperatures and/or fields, these films have been described in terms of the multiple spin exchange model. However, two-dimensional systems are extremely sensitive to anisotropies such as nuclear dipole interactions, even when they are several orders of magnitude less than the dominant exchange mechanism

[en] The measurement results of intrinsic flood field uniformity and maximum count rate were analysed and compared among the four different manufacturers' SPECTs. It was found that the descriptions mentioned above were different from those stated by manufacturers and some were of significant difference

[en] The intrinsic flood field uniformity is an important content of SPECT QC, while many factors can contribute to the incorrect measurement of it. For the guarantee of SPECT QC, the author will discuss the subjective factors affecting the measurements of the SPECT intrinsic flood field uniformity, such as a close distance between radioactive source and detector, radiation shooting detector at an angle, the interference of radiation coming from around, insufficient total counts, higher dose of the radioactive source etc

[en] We use SQUID NMR to observe the magnetization of ³He films with densities between 20 and 24 atoms/nm² in the zero field limit. Ferromagnetism in these nearly 2D Heisenberg exchange systems is stabilized by weak anisotropies. In the ferromagnetic phase, the NMR line becomes very broad and shifts to lower frequencies, consistent with a large dipolar field opposing a perpendicular applied field. Grafoil can be modeled by a Gaussian distribution of platelet angles centered on the normal to the Grafoil plus a randomly distributed set of platelets. Using the spin dynamics of a 2D polarized sheet with reasonable assumptions for the distributions of platelet angles, we show that the magnetization, frequency shift and line shape form a consistent picture of a highly polarized sheet

[en] Radiofrequency ablation (RFA) makes use of thermal energy with a catheter delivery system to cause coagulation necrosis of the tissue. Percutaneous RFA has been well employed for many years in clinical treatment of liver tumors. The great success of RFA in treating hepatic tumors encourages the clinical physicians to use RFA in treating other solid tumors such as lung cancer. For recent years many publications have confirmed that RFA is a safe and valuable treatment option for patients with primary lung cancer or limited pulmonary metastases. This newly-developed modality has been more and more employed for lung tumors in clinical practice. Theoretically, lung tumors are very suitable to RFA because lesion's surrounding air within the adjacent normal parenchyma has an insulation effect, thus facilitating energy concentration within the tumor tissue. However, ablation technique used for lung tumors is quite different in many ways when compared with the ablation technique used for the malignancies of other organs. This paper aims to discuss some critical considerations of RFA for lung malignancies, such as indications, perioperative preparations, technical requirements, prevention of complications, follow-up imaging examination, the evaluation of therapeutic efficacy, etc. Presently, RFA is most used for the patients with inoperable early -stage lung cancers or for the patients with small and favorably located pulmonary metastases. The specific features of lung tissue require different power energy. The precise placement of electronic needle and the careful manipulation during RFA procedure are the key points to ensure a satisfactory result and to avoid injury to non-targeted important structures. PET/CT seems to be the most accurate follow-up means, although its role in assessing the local changes of the tumor shortly after RFA needs to be further clarified. For stage I non-small-cell lung cancer and limited pulmonary metastases, RFA provides satisfactory survival rate. (authors)

[en] Apoptosis radionuclide imaging is a novel method for the detection of apoptosis, characterised with direct, noninvasive and real-time imaging. It is useful in the observation of brain and myocardial ischemic reperfusion injury, detection of organ graft rejection and evaluation of tumor chemotherapy and radiotherapy effect, but further investigation should be done

[en] The new fuel element transportation container is a specific equipment designed for transporting 493 reactor's fuel elements. In order to insure the safety of fuel elements during transportation and fulfill the requirements of standard GB 11806-2004, thermal design calculation and validation experiments were carried out. The accuracy of the container's thermal design was proven by comparing thermal design results with thermal experimental data. The safety of the new fuel elements can be insured and the requirements of GB 11806-2004 can be fulfilled by using the new fuel elements transportation container under both normal transport condition and accidental transport condition. (authors)

[en] The experimental study is aimed at achieving the effect of hepatic tumor and tumor-bearing lobar or segmental resection by using combined transcatheter hepatic arterial embolization and retrograde hepatic venous embolization (THAE-RHVE) in experimental study. THAE-RHVE was carried out in 8 mongrel dogs. Hepatic arterial embolization was performed by injecting lipiodol followed by gelatin sponge particles, following complete occlusion of the hepatic vein with balloon catheter. Retrograde hepatic venous embolization (RHVE) was then performed by injecting a mixture of absolute ethanol and meglumini diatrizoatis (MD) via the inflated balloon catheter. Ethanol and MD were combined with a ratio of 1:1. RHVE alone was performed in 4 dogs as control. The animals were followed up for 1∼8 weeks with liver function test, CT, gross and microscopic examinations. There was no technical failure or procedural complications. Transient elevation of AST and ALT levels was seen immediately in both groups after the procedure. Follow-up CT after 3 weeks showed dense lipiodol accumulation in the embolized lobe or segment and the corresponding portal branches in the THAE-RHVE animals. At 1 week after THAE-RHVE, complete coagulation necrosis was seen at histologic examination in the embolized lobe. The hepatic vein and portal branches of the embolized area had thickened walls and were filled with thrombus. At 2 weeks, granulomatous tissue and inflammatory cell infiltration surrounding the necrotic area could be seen. At 4∼8 weeks, marked atrophy of the embolized lobe was found, and the necrotic area was progressively reducing in size and being replaced by fibrosis. In the control group, incomplete segmental coagulated necrosis was seen and the necrosis area wa smaller than that of THAE-REVE. Hepatic lobectomy or segmentectomy can be achieved with THAE-RHVE. This new method is safe and easy, and may be useful in the treatment of HCC

[en] Naturalcirculation valve is a key equipment of the residual heat removal system of pool-typed low temperature heating reactor. The natural circulation valve is placed on the side wall of the reactor core vessel which can connect the fluid inside and outside the vessel together. Its natural circulation function is achieved by hydraulic closing and passive opening. When the main pump of the primary loop is running, the natural circulation valve remains closed under the normal working condition by branch jetting. After the reactor is shut down, the pressure difference between the inner and outer surfaces of the natural circulation valve is continuously reduced, and the valve is automatically opened because of its gravity. When the fluid inside and outside the vessel is connected, a nature circulation will be established because of the temperature difference and the passive removal of the residual heat of the reactor core is achieved. This is important for ensuring the safe operation of the reactor. A nature circulation valve that meets the functional requirements can be finally designed by structure design and torque balance calculation. (authors)

[en] Heavy water heat exchanger is an important equipment of heavy water system in the two constructing research reactors. The heavy water heat exchangers in the two research reactors were optimized in type selection and design phase. The plate heat exchanger is safer and more economic than that of glove tube heat exchanger. The application of plate heat exchanger in heavy water system gives good experience for future research reactor design. (authors)