Influence of SENSE on image properties in high-resolution single-shot echo-planar DTI.

Limited spatial resolution is a key obstacle to the study of brain white matter structure with diffusion tensor imaging (DTI). In its frequent implementation with single-excitation spin-echo echo-planar sequences, DTI's ability to resolve small structures is strongly restricted by T2 and T2* decay, B0 inhomogeneity, and limited signal-to-noise ratio (SNR). In this work the influence of sensitivity encoding (SENSE) on diffusion-weighted (DW) image properties is investigated. Computer simulations showed that the PSF becomes narrower with increasing SENSE reduction factors, R, enhancing the intrinsic resolution. After a brief theoretical discussion, we describe the estimation of SNR on a pixel-by-pixel basis as a function of R. The mean image SNR behavior is manifold: SENSE is capable of increasing SNR efficiency by reducing the echo time (TE). Each SNR(R) curve reveals a maximum that depends on the amount of partial Fourier encoding used. The overall best SNR efficiency for an eight-element head coil array and a b-factor of 1000 s/mm2 is achieved at R = 2.1 and partial Fourier encoding of 60%. In vivo tensor maps of volunteers and a patient, with an in-plane resolution of 0.78 x 0.78 mm2, are also presented to demonstrate the practical implementation of the parallel approach.     

颈椎前路手术后邻近节段运动变化的生物力学研究

目的利用压敏片(PSF)技术,测量颈椎前路手术后关节突关节内压力的变化,探讨颈前路手术后远期邻近节段退变的生物力学发病机制。方法10具新鲜成人颈椎尸体标本(C2～T1),行前路C4,5椎间盘切除、C4,5椎间植骨钢板内固定术。将压敏片置于关节突关节内,在脊柱三维运动试验机上测量0载荷和2N·m载荷下,后伸、左右侧弯、左右旋转过程中关节突关节内压力的变化。结果颈椎前路手术后,邻近节段关节突关节内的压力增加,以后伸和左右旋转时最为明显,差异有显著性意义(P<0.05)。结论颈椎前路短节段植骨融合术后,邻近节段关节突关节内压力明显增加,可诱发邻近节段关节突关节的退变,从而引起相应的病症。     

MFI-20应用于脑卒中后疲乏(PSF)的诊断价值

目的 探索多维疲乏目录（Multidimensional Fatigue Inventory,MFI-20）对脑卒中后疲乏（post-stroke fatigue,PSF）的诊断价值。方法 采用方便抽样法抽取328例脑卒中患者作为研究对象,以疲乏严重度量表（Fatigue Severity Scale,FSS）结果为诊断标准,评估MFI-20诊断PSF的效能。结果 328例患者中,136例使用FSS诊断PSF（41.5%）,153例应用MFI-20诊断PSF（46.6%）。以FSS为标准,MFI-20对PSF的诊断符合率为91.8%,Kappa值为0.833,灵敏度为96.3%,特异度为88.5%,阳性预测值为85.6%,阴性预测值为97.1%。MFI-20诊断PSF的ROC曲线下面积为0.924。结论 MFI-20具有良好的诊断价值,其多维的特点与PSF的复杂性相契合,可作为PSF的诊断工具。     

Point spread function mapping with parallel imaging techniques and high acceleration factors: fast, robust, and flexible method for echo-planar imaging distortion correction.

Echo-planar imaging (EPI) is an ultrafast magnetic resonance (MR) imaging technique prone to geometric distortions. Various correction techniques have been developed to remedy these distortions. Here improvements of the point spread function (PSF) mapping approach are presented, which enable reliable and fully automated distortion correction of echo-planar images at high field strengths. The novel method is fully compatible with EPI acquisitions using parallel imaging. The applicability of parallel imaging to further accelerate PSF acquisition is shown. The possibility of collecting PSF data sets with total acceleration factors higher than the number of coil elements is demonstrated. Additionally, a new approach to visualize and interpret distortions in the context of various imaging and reconstruction methods based on the PSF is proposed. The reliable performance of the PSF mapping technique is demonstrated on phantom and volunteer scans at field strengths of up to 4 T.     

The Thickness Effect of PSF Nanofibrous Mat on Fracture Toughness of Carbon/Epoxy Laminates

The geometrical features of nanofibers, such as nanomat thickness and the diameter of nanofibers, have a significant influence on the toughening behavior of composite laminates. In this study, carbon/epoxy laminates were interleaved with polysulfone (PSF) nanofibrous mats and the effect of the PSF nanomat thickness on the fracture toughness was considered for the first time. For this goal, the nanofibers were first produced by the electrospinning method. Then, double cantilever beam (DCB) specimens were manufactured, and mode-I fracture tests were conducted. The results showed that enhancing the mat thickness could increase the fracture toughness considerably (to about 87% with the maximum thickness). The toughening mechanism was also considered by presenting a schematic picture. Micrographs were taken using a scanning electron microscope (SEM).     

Case studies putting the decision-making framework for the grouping and testing of nanomaterials (DF4nanoGrouping) into practice

Case studies covering carbonaceous nanomaterials, metal oxide and metal sulphate nanomaterials, amorphous silica and organic pigments were performed to assess the Decision-making framework for the grouping and testing of nanomaterials (DF4nanoGrouping). The usefulness of the DF4nanoGrouping for nanomaterial hazard assessment was confirmed. In two tiers that rely exclusively on non-animal test methods followed by a third tier, if necessary, in which data from rat short-term inhalation studies are evaluated, nanomaterials are assigned to one of four main groups (MGs). The DF4nanoGrouping proved efficient in sorting out nanomaterials that could undergo hazard assessment without further testing. These are soluble nanomaterials (MG1) whose further hazard assessment should rely on read-across to the dissolved materials, high aspect-ratio nanomaterials (MG2) which could be assessed according to their potential fibre toxicity and passive nanomaterials (MG3) that only elicit effects under pulmonary overload conditions. Thereby, the DF4nanoGrouping allows identifying active nanomaterials (MG4) that merit in-depth investigations, and it provides a solid rationale for their sub-grouping to specify the further information needs. Finally, the evaluated case study materials may be used as source nanomaterials in future read-across applications. Overall, the DF4nanoGrouping is a hazard assessment strategy that strictly uses animals as a last resort.     

Preparation of high thermal stability polysulfone microcapsules containing lubricant oil and its tribological properties of epoxy composites

Polysulfone (PSF) microcapsules containing lubricant oil have been successfully prepared using solvent evaporation method. The results show that lubricant oil was successfully encapsulated and the encapsulation capacity of about 56.0?wt.% was achieved. The uniform microcapsules have nearly spherical shape and quite smooth outer surface. The mean diameter is approximately 156 and 169?μm by using different dispersant solutions. The wall material is porous in structure with wall thickness of about 20?μm. The initial decomposition temperature of PSF is 480?°C. It is higher than traditional poly(urea-formaldehyde) (PUF) and poly(melamine-formaldehyde) (PMF) wall materials with 245?°C and 260?°C initial decomposition temperature, respectively. High thermal stability of PSF microcapsules can be considered as additives in high temperature resistant polymer materials. The frictional coefficient and wear rate of epoxy composites decreased significantly by incorporating microcapsules containing lubricant oil into epoxy. When the concentration of microcapsules was 25?wt.%, the frictional coefficient and specific wear rate were reduced by 2.3 and 18.3 times, respectively, as compared to the neat epoxy.     

富含脯氨酸和谷氨酰胺的剪切因子:预测血液肿瘤耐药的潜在靶点

 【摘要】　目的　鉴定血液肿瘤细胞耐药相关膜抗原,探讨其在血液肿瘤细胞膜易位表达的普遍性。方法　以蛋白电泳和免疫共沉淀法分离并沉淀细胞膜抗原,以质谱分析鉴定抗原信息,通过siRNA基因干扰法和激光共聚焦显微镜法确证抗原信息及其易位细胞膜的鉴定结果,通过流式细胞术检测抗原在多种血液肿瘤细胞膜的易位表达。结果　免疫共沉淀和质谱等实验证实白血病耐药相关单抗———5D12在HL-60细胞膜抗原为细胞核因子富含脯氨酸和谷氨酰胺的剪切因子（PSF）,经一系列生物学实验确证PSF在HL-60细胞膜的易位表达,在敏感株的膜表达显著高于耐药株的膜表达。流式细胞术检测结果表明PSF的特异性单抗5D12与血液肿瘤多种细胞系的膜结合率为：HL-60（78.56±0.76）%;K562（26.54±4.42）%;Nomalwa（38.10±5.11）%;U937（64.03±7.96）%;Jurkat（29.12±5.58）%;Raji（74.92±3.41）%;CEM（12.18±3.21）%。结论　核蛋白PSF易位表达于多种血液肿瘤细胞膜,对维持肿瘤细胞对化疗药的敏感性有重要作用,是血液肿瘤耐药预测的候选靶点。     

过表达DBHS家族基因可促进食管鳞癌细胞的迁移侵袭

目的 研究人类剪切蛋白(drosophila behavior human splicing,DBHS)家族基因,包括p5nrb、PSF、PSPC1基因,对食管鳞状细胞癌(以下简称食管磷癌)细胞系TE-8细胞系迁移、侵袭能力的影响。方法 构建p54nrb、PSF、PSPC1基因过表达载体,通过脂质体法转染TE-8细胞,转染48 h后qRT-PCR和Western blotting检测各组细胞p54nrb、PSF、PSPC1在mRNA和蛋白质水平的表达。细胞划痕实验及覆盖有Matrigel的Transwell小室检测食管鳞癌细胞的迁移、侵袭能力。结果 过表达p54nrb、PSF、PSPC1后,qRT-PCR和Western blotting检测证实食管鳞癌TE-8细胞中上述基因表达在mRNA水平和蛋白质水平均明显上调,细胞划痕实验及Transwell小室实验证实食管鳞癌TE-8细胞过表达p54nrb、PSF、PSPC1后,其迁移、侵袭能力增强。结论 过表达DBHS家族基因可促进食管鳞癌细胞的迁移侵袭。