Further study on different dopings into PbWO4 single crystals to increase the scintillation light yield

Since we presented our preliminary result (Nucl. Instr. and Meth. A 486 (2002) 170) at SCINT2001, we have continued our efforts to increase the light yield (LY) of PbWO₄ scintillators by extending different dopings with an aim to find a possibility of using PbWO₄ successfully in Positron Emission Tomography (PET). Overall result obtained for single doping as well as double and tripple co-dopings are summarized, including decay characteristics and radiation hardness. The LY in non-doped PbWO₄ crystals with a size of 10×10×(20–30) mm³ is 25–35 photolectrons/MeV (phe/MeV) corresponding to 3–4% of the LY in BGO, when measured with a bialkali photomultiplier during a gate of 1 μs. The maximum LY increased to 49 phe/MeV for single doping with Mo⁶⁺, 80 phe/MeV for double co-doping of Mo⁶⁺+Sb⁵⁺, and 85 phe/MeV for tripple co-doping of Mo⁶⁺+Cd²⁺+Sb⁵⁺. The radiation hardness is larger than 10⁵ Gy for each of the samples co-doped with Mo⁶⁺+Sb⁵⁺ and Mo⁶⁺+Cd²⁺+Sb⁵⁺, while it is much poorer in PWO:Mo⁶⁺. In each of these co-doped samples, a medium-speed green emission in the microsecond range is created besides the fundamental fast (a few nanoseconds range) blue one, giving a peak at 500 nm in the radioluminescence spectrum similarly as in PWO:Mo⁶⁺.     

聚酯生产过程质量指标软测量和优化控制系统

以大型聚酯工业生产过程为对象，总结了指标的软测量和优化控制系统软件的总体结构。该软件由以模型为基础的关键质量指标的软测量与可在DCS系统上，及计算机控制语言（MATLAB）平台上，在线实时运行的PET优化控制软件系统两部分组成。控制软件包括质量指标在线检测系统、酯化率在线开环优化操作指导、酯化率预测控制系统、终缩聚粘度神经元网络自适应控制系统和反应釜位故障诊断系统。该软件已应用于指导和控制实际生产过程。     

国内正电子发射断层(PET)现状和展望

介绍了国内外正电子发射断层(PET)发展概况。截止2003年3月，国内有22个PET中心(包括已建、在建和计划中)、4台PET单机。正电子药物(^18F—FDG)方面：除由IBA公司2台30MeV回旋加速器生产的^18F—FDG已进入临床研究外，PET中心的17台小型回旋加速器生产的FDG按医院制剂使用。2001年FDGPET检查约6700人次。本文讨论了我国PET发展中应注意的几个问题：如PET目前未进入医疗保险；PET中心数目的发展，宜在国家主管部门统一规划下并根据社会经济发展水平、医院功能定位及社会和公众的承受能力，合理布局、有限量地增加；加强基础科学与临床医学协作；重视人才培养及培训；建议核学会或核医学会下属设立PET学组或专门委员会，以作为各PET中心和主管部门联系的纽带与桥梁。     

无机/有机纳米复合聚酯材料——技术开发和应用市场

层状硅酸盐经过有机化相容处理后,通过聚合插层法或熔体插层法将无机层状硅酸盐与聚酯复合,形成新的层状硅酸盐聚酯纳米复合材料。纳米聚酯的种类包括属于饱和聚酯的PET、PBT、PTT、PCT、PC、PLA及属于不饱和聚酯的各种配方。纳米聚酯材料在塑料、包装、纤维、农业等领域的诸多应用,如塑料啤酒瓶、PET工程塑料、抗茵纤维、回收再生料、纳米PC塑料、抗菌不饱和树脂制品等,使其具有巨大的开发应用价值。     

涤纶膜（PET）表面的氟化处理及其结构的XPS研究

详细描述了ＣＦ４／ＣＨ４混合气体等离子体处理涤纶膜（ＰＥＴ）表面的过程。利用Ｘ光电子能谱（ＸＰＳ）研究处理后ＰＥＴ的表面结构、性质以及处理后样品的浸水行为。结果表明,ＰＥＴ经碳氟等离子体处理后,其表面覆盖上一层具有憎水功能的氟化层,氟化层的结构与碳氟混合气体的组成有关;混合气体等离子体在ＰＥＴ表面形成化学组成均匀、交联结构的处理层;纯ＣＦ４等离子体的处理结果则以刻蚀作用为主,处理层的化学组成不均匀     

脑功能网络核心节点及网络稳定性研究

采用偏相关的计算方法对大脑的正电子断层发射成像建立脑区间的功能连接网络,利用小世界网络中节点度和节点介数求出大脑网络中的核心节点并对应到解剖学结构中,通过随机攻击和对核心节点的目标攻击研究网络的稳定性.结果表明,大脑网络具有明显的小世界拓扑结构,拥有较高度和较大节点介数的节点为网络的核心节点,从而得出正常人大脑的核心节点主要分布在额叶和顶叶区域,通过随机攻击和对节点中心的目标攻击得出大脑网络具有较强的鲁棒性和脆弱性.     

冷等离子体处理对涤纶纤维表面性能的影响

采用冷等离子体技术处理涂纶纤维,利用ESCA分析了冷等离子体处理前后的纤维表面元素组成,官能团类型的变化,通过比较处理前后浸润性,涂纶纤维／环氧复合材料的层间剪切强度,研究了冷等离子处理对涤纶纤维表面性质的影响,结果表明：绦纶纤维经冷等离子处理后表面含氧的极性基团增加,纤维表面的浸润性显著改善,涤纶纤维／环氧复合材料界面性能增强。     

熔融插层法制备PET/蒙脱土纳米复合材料及其性能的研究

采用熔融插层法制备PET/蒙脱土纳米复合材料.对制备的PET/蒙脱土纳米复合材料进行表征和研究,通过XRD分析了PET基体中蒙脱土片层的插层情况,发现达到预期效果;试验数据表明:有机蒙脱土使复合材料的拉伸强度和弯曲强度下降,拉伸模量和弯曲模量上升;随着有机蒙脱土含量的增加,复合材料的阻隔性能得到提高.     

高模量涤纶纤维的结构弱节特征及力学行为

采用断面形态特征与纤维对应拉伸曲线组合的对比分析方法,讨论了歼雉的结构弱节及拉伸行为。结果表明,涤纶纤维的弱节主要是表层缺陷及其扩展所引起的,其力学性能为低应力、低应变、低断裂功特征。     

Systematic Review: Targeted Molecular Imaging of Angiogenesis and Its Mediators in Rheumatoid Arthritis

Extensive angiogenesis is a characteristic feature in the synovial tissue of rheumatoid arthritis (RA) from a very early stage of the disease onward and constitutes a crucial event for the development of the proliferative synovium. This process is markedly intensified in patients with prolonged disease duration, high disease activity, disease severity, and significant inflammatory cell infiltration. Angiogenesis is therefore an interesting target for the development of new therapeutic approaches as well as disease monitoring strategies in RA. To this end, nuclear imaging modalities represent valuable non-invasive tools that can selectively target molecular markers of angiogenesis and accurately and quantitatively track molecular changes in multiple joints simultaneously. This systematic review summarizes the imaging markers used for single photon emission computed tomography (SPECT) and/or positron emission tomography (PET) approaches, targeting pathways and mediators involved in synovial neo-angiogenesis in RA.