SiBN(C)陶瓷纤维先驱体的表征及熔融纺丝

以B(NHCH_3)_3和Si(NHCH_3)_4为小分子先驱体,在一定条件下通过共缩聚反应得到聚硅硼氮烷,经熔融纺丝得到SiBN(C)陶瓷先驱体纤维;采用红外光谱、核磁共振、元素分析等手段研究了小分子先驱体的配比对聚硅硼氮烷结构的影响。结果表明:聚硅硼氮烷存在B—N六元环、Si—N、Si—N—B、N—H等主要官能团,熔融纺丝实验表明Si(NHCH_3)_4与B(NHCH_3)_3体积比为1:1.3的聚硅硼氮烷具有良好的可纺性,可得到连续可卷绕的聚硅硼氮烷纤维,其纤维表面光滑,直径为50～60μm。

MRI of gastric carcinoma:Results of T and N-staging in an in vitro study

AIM： To determine the accuracy of 1.5-T magnetic resonance imaging （MRI） in the evaluation of gastric wall invasion and perigastric lymph node metastasis in gastric adenocarcinoma.METHODS： Twenty resected gastric specimens containing 20 tumors were studied with a 1.5-T MR system using a commercial head surface coil. MR scanning was performed with a T1 weighted image （TR/TE = 500/20）, and a T2 weighted image （TR/TE = 2500/90）. MR findings were compared with pathologic findings.RESULTS： A T1-weighted image demonstrated three layers in the normal gastric wall. All of the gastric tumors were well demonstrated by lesions and location. In a MRI findings of gastric wall invasion, there was 1 case of T1, 7 of T2, 11 of T3. Pathologic results of resected specimens included 3 cases of pT1, 4 of pT2, and 12 of pT3. The accuracy of T staging with MRI was 74% （14 of 19）. MRI findings of lymph node metastasis included 6 cases of NO, 13 cases of N1. The accuracy of the N staging with MRI was 47% （9 of 19）.CONCLUSION： MRI has a high diagnostic accuracy in the evaluation of the T staging of gastric cancerin vitro and thus potentially enables preoperative histopathologic staging.

Study of MR image for involvement of paranasal sinuses in 56 cases with nasopharyngeal carcinoma

Objective： The aim of the study was to study the nuclear magnetic resonance image （MRI） feature for involvement of paranasal sinuses in patients with nasopharyngeal carcinoma （NPC）. Methods： The MRI of 56 patients with NPC and paranasal sinuses infringed were evaluated between December 2003 and August 2004. Results： Among them, 56 （100%） showed breakage in the wall of paranasal sinuses, 29 （51.8%） had thick mucous membrane in sinuses, 36 （64.3%） showed tumour invasion sinuses, 55 （98.2%） connected with primary carcinoma with the lesion, and 14 （25%） stored up fluid in si- nuses. On MRI scan technique, the positive ratios of diagnoses were 66.1%, 76.8%, and 98.2% respectively （P 〈 0.000） in the horizontal section, coronal section and sagittal section. And nearly 60% was in the TlWl and T2Wl, but 100% in strengthen scan. Conclusion： The findings of sinuses wall breakage, thick mucous membrane in sinuses, tumour invasion cavity connective mass, and same enhancement signal in MR image may indicate the paranasal sinuses involved by primary turnout. The sagittal section and enhanced MRI scans are helpful to diagnosis.

Obstacles Facing the Implementation of Functional Magnetic Resonance Imaging （fMRI） of Brain in Jeddah City

fMRI （Functional Magnetic Resonance Imaging） is a relatively new technique that uses MRI （Magnetic Resonance Imaging） to measure the hemodynamic response （change in blood flow） related to neural activity in the brain. This paper aims to explore and identify the obstacles facing the implementation and applications of IMRI in radiology departments within Jeddah city by analyzing related data received by direct questionnaires and interviews with all the people working in MRI units in Jeddah city and finds that the major obstacle is lacking of awareness of fMRI among medical professionals and their training.

MRI and magnetic resonance angiography in evaluating simultaneous pancreas-kidney transplantation

OBJECTIVE: To evaluate the value of magnetic resonance imaging (MRI) and three dimensional (3D) contrast magnetic resonance angiography (MRA) in the diagnosis of complications of simultaneous pancreas-kidney transplantation (SPKT), as confirmed by biopsy and digital subtraction angiography (DSA). METHODS: Five MR examinations of five patients were performed within 28 days to 2 years after surgery on GE 1.5T MR system. Imaging techniques included axial and sagittal chemical fat-suppressed T1-weighted image (T1WI) and T2-weighted image (T2WI), additional contrast axial or saggital chemical fat-suppressed T1WI were obtained after 3D contrast MRA for calculating the mean percentage of the parenchymal enhancement (MPPE) of the pancreas and kidney. 3D contrast MRA was performed with Smartprep technique. MRA data were analyzed with maximum intensity projection (MIP) and multi-planner reformat (MPR). RESULTS: In five cases of transplant pancreases, MRI found two normal pancreas grafts, one case of acute rejection, one case of chronic rejection with 70% fibrosis and one case of late pancreatitis. In five transplant kidneys, MRI detected four normal kidney grafts and one case of acute rejection with infarction. MPPE could distinguish infarction from other complications. 3D contrast MRA could display vascular complications of SPKT, such as stenosis or occlusion, aneurysm formation of transplanted vessels and narrowing at the site of anastomosis, as confirmed by DSA. CONCLUSION: With combined application of MRI and 3D contrast MRA, complications of SPKT can be clearly identified.

Recent advances in biological detection with magnetic nanoparticles as a useful tool

Magnetic nanoparticles have emerged as a powerful tool for magnetic resonance imaging, biodetection, drug delivery, and hyperthermia. This review focuses on the biological detection of magnetic nanoparticles as well as their physicochemical properties. Substantial progress in the sensitivity of detection has been made by developing variety of methods. Five applications of magnetic nanoparticles in biological detection are discussed in this review: magnetic separation, magnetic sensing, magnetic manipulation, magnetic catalysis, and signal enhancer for surface plasmon resonance(SPR). Finally, some future trends and perspectives in these research areas are outlined.