A TOF-PET prototype with position sensitive PMT readout

A prototype of time-of-flight positron emission computed tomography (TOF-PET) has been developed for acquiring the coincident detection of 511 keV gamma-rays produced from positron annihilation. It consists of two 80.5 mmx80.5 mm LYSO scintillator arrays (composed of 35 x35 pixel finger crystals) with the position sensitive photomultiplier tubes R2487 as the readout. Each array is composed of 2 mm x2 mm x 15 mm finger crystals and the average pixel pitch is 2.30 mm. The measured results indicate that the TOF information has the potential to significantly enhance the image quality by improving the noise variance in the image reconstruction. The best spatial resolution (FWHM) of the prototype for the pairs of 511 keV gamma-rays is 1.98 mm and 2.16 mm in the x and y directions, respectively, which are smaller than the average pixel pitch of 2.30 mm.

Micro-PET探测器单元的研制和模拟研究

提高癌症患者治愈率的关键是早期诊断，及时治疗。现在，癌变组织的无创伤诊断已成为癌医学诊断的发展方向和潮流，发展一种快速、准确、方便、低廉的医用肿瘤诊断影像设备是非常实际和十分有意义的课题。 本论文描述了构成便携式肿瘤影像探测器的探测单元研制，包括探测器总体构型设计，选择闪烁晶体种类、形状及尺寸、选择与之匹配的读出器件-位置灵敏光电倍增管，设计简化的读出线路。 通过模拟计算和实验测试，确定探测器单元由64块BGO晶体构成8×8方阵，晶体尺寸5.9×5.9×10mm3，探测器性能通过137Csγ放射源测试。探测单元本征位置分辨达到3.12 mm（FWHM），为了提高探测单元的本征分辨，构建了2×2×10mm3 BGO晶体的19×19矩阵探测单元，后续读出不变，本征位置分辨为1.41mm（FWHM）。这一指标接近于目前同类探测器的最好水平。在此基础上用22Na正电子放射源对双探测单元构成的Micro-PET进行成像测试，给出了清晰二维平面影像。 闪烁晶体性能测试和探测器单元性能测试都与Monte Carlo模拟结果很好符合，说明Monte Carlo模拟结果可靠，对设计优化探测器单元有指导作用。该探测单元研制结果和双单元的符合研究,为研制一种快速、准确、方便、低廉的医用肿瘤诊断成像设备—微型正电子发射断层仪（Micro-PET）提供理论和实践经验

Evaluation of different culture conditions for high-level soluble expression of human cyclin A(2) with pET vector in BL21 (DE3) and spectroscopic characterization of its inclusion body structure

In this paper, we evaluated various parameters of culture condition affecting high-level soluble expression of human cyclin A, in Escherichia coli BL21(DE3), and demonstrated that the highest protein yield was obtained using TB(no glycerol) + 0.5% glucose medium at 25 degrees C. By single immobilized metal ion affinity chromatography, we got highly purified human cyclin A(2) with a yield ranged from 20 to 30 mg/L. By amyloid-diagnostic dye ThT binding and Fourier transform infrared spectroscopy, we observed a significant decrease in alpha-helix content and an increase in beta-sheet structure in cyclin A(2) inclusion body in comparison to its native protein, and confirmed the resemblance of the internal organization of cyclin A(2) inclusion body and amyloid fibrils.

EPDM增韧PET的研究

在引发剂过氧化二异丙苯(DCP)的作用下,通过添加少量界面增容剂苯乙烯(St)提高接枝率,使甲基丙烯酸缩水甘油酯(GMA)与(乙烯/丙烯/二烯)共聚物(EPDM)反应,得到接枝物EPDM-g-GMA,将EPDM-g-GMA与PET共混,以提高共混体系的冲击强度。探讨了不同含量的EPDM-g-GMA对共混体系力学性能的影响。结果表明,随着EPDM-g-GMA含量的增加,共混体系的缺口冲击强度显著提高,当其含量为50％时,材料的缺口冲击强度为344.9J/m,约为纯PET的12倍;拉伸强度、弯曲强度和弯曲弹性模量出现一定程度的下降;EPDM-g-GMA含量为20％～30％时,材料的综合力学性能较好。

多组分单体接枝三元乙丙橡胶/PET共混体系的形态结构研究

以PS、DCP、GMA作为PET/EPDM共混体系的增容剂 ,以DSC和X射线衍射探讨了PET/EPDM共混物的结晶性能 ,以偏光显微镜和扫描电子显微镜探讨了共混物的形态。结果表明 ,PET/g EPDM共混体系的熔点可提高10℃ ,玻璃化温度降低 ,结晶起始温度提高约 2 0℃。共混体系中 ,当EPDM含量低时 ,PLM下观察到的是较为完整的球晶 ,随着EPDM含量逐渐提高 ,观察得到的是不完善的球晶、微晶、晶粒这样一个晶体变化过程 ,结晶完善程度降低。

成核剂1,3:2,4-二(亚苄基)-D山梨醇对PET/PEN共混体系结构和结晶形态影响

利用差示扫描量热仪、X射线衍射仪、正交偏光显微镜研究了成核剂 1,3 :2 ,4-二 (亚苄基 ) -D山梨醇(DBS)对聚对苯二甲酸乙二醇酯 (PET) /聚 2 ,6-萘二甲酸乙二醇酯 (PEN)共混体系的结构及结晶形态的影响。结果表明 :成核剂的加入 ,使PET/PEN共混体系熔融起始温度升高 10℃左右 ,结晶峰形变尖锐 ,说明加入成核剂后有效促进了PET/PEN共混体系的结晶。实验结果表明 :成核剂含量低于 1%时 ,PET/PEN共混体系晶体的球晶完整。成核剂含量大于 3 %时 ,PET/PEN /DBS共混体系晶体的球晶碎小。成核剂的加入 ,能够有效地减小球晶尺寸和降低球晶的完善性

Sudies on non-isothermal melt crystallization kinetics in PET/PEN/DBS blends

Macrokinetic models, namly the modified Avrami, Ozawa and Zibicki models, were applied to study the non-isothermal melt crystallization process of PET/PEN/DBS blends by DSC measurement. The modified Avrami model was found to describe the experimental data fairly well. With the cooling rates in the range from 5 to 20 K/min, Ozawa model could be well used to describe the early stages of crystallization. However, Ozawa model did not fit the polymer blends during the late stages of crystallization, because it ignored the influence of secondary crystallization. The crystallization ability of the blends decreases with increasing the DBS content from analysis by using Ziabicki kinetic model, which is similar to the results based on calculation of the effective energy barrier of the blends.

热致液晶（LC70）／PET共混物的结构与性能

采用ＷＡＸＤ、ＤＳＣ、ＰＯＭ、ＳＥＭ和力学测试方法研究了ＬＣ７０／ＰＥＴ原位复合材料的结构与性能。结果表明，当ＬＣ７０／ＰＥＴ＜２０％时，ＬＣ７０对ＰＥＴ的结晶生长具有一定促进作用；当ＬＣ７０／ＰＥＴ＞３０％时，共混物结晶能力迅速下降，结晶放热和熔融焓明显降低。ＬＣ７０可起到加速成核作用。ＬＣ７０与ＰＥＴ部分相容，在较高ＬＣ７０含量下的ＳＥＭ观察表明，存在清晰的“皮－芯”结构。

PET／EVA共混体系的流变行为和形态

用恒负荷式毛细管流变仪研究了ＰＥＴ／ＥＶＡ共混物的流变行为，讨论了ＥＶＡ对ＰＥＴ流变行为的影响；并用ＳＥＭ观察了挤出条横截面的形态。结果表明，在一定范围内，加入ＥＶＡ能够提高ＰＥＴ的表观粘度，改善其加工性能；电镜结果表明ＰＥＴ和ＥＶＡ明显分相；动态力学结果证明ＰＥＴ和ＥＶＡ不相容。

PET-EVA共混体系的结晶与熔融行为

用热分析法测定了PET-EVA共混物在不同条件下的结晶与熔融行为.结果表明,加入EVA使PET结晶温度降低,结晶温度区间变窄,结晶度有一定提高,在EVA含量10％附近出现极值.总体上讲,EVA对PET的熔融行为没有影响.

Progettazione e sintesi di nuovi antagonisti CB1 a struttura pirazolica come potenziali radiofarmaci per la PET imaging

Cannabinoid receptors are members of the large family of G-protein coupled receptors. Two types of cannabinoid receptor have been discovered: CB1 and CB2. CB1 receptors are localised predominantly in the brain whereas CB2 receptors are more abundant in peripheral nervous system cells. CB1 receptors have been related with a number of disorders, including depression, anxiety, stress, schizophrenia, chronic pain and obesity. For this reason, several cannabinoid ligands were developed as drug candidates. Among these ligands, a prominent position is occupied by SR141716 (Rimonabant), which is a pyrazole derivative with inverse agonist activity discovered by Sanofi-Synthelabo in 1994. This compound was marketed in Europe as an anti-obesity drug, but subsequently withdrawn due to its side-effects. Since the relationship between the CB1 receptors’ functional modification, density and distribution, and the beginning of a pathological state is still not well understood, the development of radio-ligands suitable for in vivo PET (Positron Emission Tomography) functional imaging of CB1 receptors remains an important area of research in medicine and drug development. To date, a few radiotracers have been synthesised and tested in vivo, but most of them afforded unsatisfactory brain imaging results. A handful of radiolabelled CB1 PET ligands have also been submitted to clinical trials in humans. In this PhD Thesis the design, synthesis and characterization of three new classes of potential high-affinity CB1 ligands as candidate PET tracers is described.

Imaging of musculoskeletal bacterial infections by [124I]FIAU-PET/CT.

BACKGROUND: Traditional imaging techniques for the localization and monitoring of bacterial infections, although reasonably sensitive, suffer from a lack of specificity. This is particularly true for musculoskeletal infections. Bacteria possess a thymidine kinase (TK) whose substrate specificity is distinct from that of the major human TK. The substrate specificity difference has been exploited to develop a new imaging technique that can detect the presence of viable bacteria. METHODOLOGY/PRINCIPAL FINDINGS: Eight subjects with suspected musculoskeletal infections and one healthy control were studied by a combination of [(124)I]FIAU-positron emission tomography and CT ([(124)I]FIAU-PET/CT). All patients with proven musculoskeletal infections demonstrated positive [(124)I]FIAU-PET/CT signals in the sites of concern at two hours after radiopharmaceutical administration. No adverse reactions with FIAU were observed. CONCLUSIONS/SIGNIFICANCE: [(124)I]FIAU-PET/CT is a promising new method for imaging bacterial infections.

Coupled Temperature-Displacement Modelling of Injection Stretch Blow Moulding of PET bottles using Buckley Model

This study presents a fully coupled temperature–displacement finite element modelling of the injection stretch-blow moulding (ISBM) process of polyethylene terephthalate (PET) bottles using ABAQUS with a view to optimising the process conditions. A physically-based material model (Buckley model) was used to predict the mechanical behaviour of PET at temperatures slightly above its glass transition temperature. A model incorporating heat transfer between the stretch rod, the preform and the mould was built using axisymmetric solid elements. Extensive finite element analyses were carried out to predict the deformation, the distribution and history of strain and temperature during ISBM of a 20 g–330 ml bottle, which was made in an in situ test on a Sidel SB06 machine. Comparisons of numerical results with the measurements demonstrate that the model can satisfactorily model the sidewall thickness and material distributions. It is also shown that significant non-linear differentials exist in temperature and strain in both bottle thickness and length directions during the process. This justifies the employment of a volume approach to accurately predict the final mechanical properties of the bottles governed by the orientation and crystallinity which are highly temperature and strain dependent.