多模态影像学检查在诊断早期强直性脊柱炎骶髂关节疾病中的效果

目的:探究在早期强直性脊柱炎骶髂关节疾病诊断中不同放射影像学检查方法的应用效果。方法:抽取2018年5月-2020年1月本院收治的早期强直性脊柱炎骶髂关节疾病患者65例作为研究对象,所有患者均开展X线、CT、MRI影像学检查,对比三种不同影像学检查方法的检出率、影像学特征。结果:X线、CT、MRI检出率分别为38.46%(25/65)、60.00%(39/65)、76.92%(50/65),检出率相比,MRI、CT明显高于X线,P<0.05;X线、CT、MRI影像学特征,发现关节间隙出现不同的异常,如关节面出现侵蚀、骨质囊变现象,关节面下骨质出现硬化与关节软骨出现肿胀,其中MRI、CT检查,阳性率高于X线,P<0.05。而对于软组织肿胀、骨髓水肿、滑膜炎症、关节滑膜增厚等现象,只能通过MRI检查才能诊断。结论:在早期强直性脊柱炎骶髂关节疾病诊断中,X线、CT、MRI影像学检查均具有一定的指导意义,而MRI不仅可以提高检出率,还能准确反映微小病灶及其软组织病变,对于早期发现骶髂关节炎值得推荐。     

Tissue-Specific Ferritin- and GFP-Based Genetic Vectors Visualize Neurons by MRI in the Intact and Post-Ischemic Rat Brain

(1) Background: Neurogenesis is considered to be a potential brain repair mechanism and is enhanced in stroke. It is difficult to reconstruct the neurogenesis process only from the histological sections taken from different animals at different stages of brain damage and restoration. Study of neurogenesis would greatly benefit from development of tissue-specific visualization probes. (2) Purpose: The study aimed to explore if overexpression of ferritin, a nontoxic iron-binding protein, under a doublecortin promoter can be used for non-invasive visualization of neurogenesis using magnetic resonance imaging (MRI). (3) Methods: Ferritin heavy chain (FerrH) was expressed in the adeno-associated viral backbone (AAV) under the doublecortin promoter (pDCX), specific for young neurons, in the viral construct AAV-pDCX-FerrH. Expression of the enhanced green fluorescent protein (eGFP) was used as an expression control (AAV-pDCX-eGFP). The viral vectors or phosphate-buffered saline (PBS) were injected intracerebrally into 18 adult male Sprague–Dawley rats. Three days before injection, rats underwent transient middle-cerebral-artery occlusion or sham operation. Animals were subjected to In vivo MRI study before surgery and on days 7, 14, 21, and 28 days after injection using a Bruker BioSpec 11.7 T scanner. Brain sections obtained on day 28 after injection were immunostained for ferritin, young (DCX) and mature (NeuN) neurons, and activated microglia/macrophages (CD68). Additionally, RT-PCR was performed to confirm ferritin expression. (4) Results: T2* images in post-ischemic brains of animals injected with AAV-pDCX-FerrH showed two distinct zones of MRI signal hypointensity in the ipsilesioned hemisphere starting from 14 days after viral injection—in the ischemic lesion and near the lateral ventricle and subventricular zone (SVZ). In sham-operated animals, only one zone of hypointensity near the lateral ventricle and SVZ was revealed. Immunochemistry showed that ferritin-expressing cells in ischemic lesions were macrophages (88.1%), while ferritin-expressing cells near the lateral ventricle in animals both after ischemia and sham operation were mostly mature (55.7% and 61.8%, respectively) and young (30.6% and 7.1%, respectively) neurons. RT-PCR confirmed upregulated expression of ferritin in the caudoputamen and corpus callosum. Surprisingly, in animals injected with AAV-pDCX-eGFP we similarly observed two zones of hypointensity on T2* images. Cellular studies also showed the presence of mature (81.5%) and young neurons (6.1%) near the lateral ventricle in both postischemic and sham-operated animals, while macrophages in ischemic lesions were ferritin-positive (98.2%). (5) Conclusion: Ferritin overexpression induced by injection of AAV-pDCX-FerrH was detected by MRI using T2*-weighted images, which was confirmed by immunochemistry showing ferritin in young and mature neurons. Expression of eGFP also caused a comparable reduced MR signal intensity in T2*-weighted images. Additional studies are needed to investigate the potential and tissue-specific features of the use of eGFP and ferritin expression in MRI studies.     

Characterisation of moisture migration of shiitake mushroom (Lentinula edodes) during storage and its relationship to quality deterioration

Water is a critical factor influencing the quality of mushrooms. This paper investigated the moisture migration of shiitake mushroom during storage using low-field nuclear magnetic resonance (LF-NMR) and magnetic resonance imaging (MRI) and its relationship to quality deterioration. Three water components assigned as water in different cell compartments of cell wall, cytoplasm and vacuole were observed in shiitake mushroom matrix. As the prolonging of storage time, the right shift of immobilised water and left shift of free water led to the merge of these two peaks at the end of storage. The increase in peak area of water in cytoplasm and decrease in the peak area of water in vacuole indicated evident moisture migration from vacuole to cytoplasm. MRI images showed heterogeneous water distribution in shiitake mushroom, and the water migrated from centre to surface, then evaporated to the environment. Besides, the moisture migration might be related to the weight loss and textural softening of shiitake mushroom.     

Diagnosis of disc bulge and disc desiccation in lumbar MRI using concatenated shape and texture features with random forest classifier

Disc bulge and disc desiccation are the most common abnormalities occurring in the spine, which leads to severe low back pain. Despite computer-aided automatic abnormality diagnostic imaging systems are available still there is a need for betterment in diagnostic accuracy and in processing time. Image processing with combined imaging features like shape and texture has given better diagnostic ability when compared with processing with individual features. In the present study, the desiccated and bulged Intervertebral Discs (IVDs) are diagnosed automatically by combining shape features extracted using Histogram of Oriented Gradients (HOG) and texture feature extracted using novel Local Sub-Rhombus Binary Relation Pattern (LS-RBRP) techniques with Random Forest (RF) classifier. The performance analysis projects that the RF with HOG+LS-RBRP has an overall better accuracy of 94.7% when compared with HOG (87%) and LS-RBRP (90.2%) with RF classifier separately in categorizing the normal IVD, disc bulge and disc desiccation in the lumbar spine MRI.     

短肢墙预应力楼盖结构顶层端节点受力性能有限元分析

在2个短肢剪力墙无粘结预应力楼盖子空间结构模型的低周反复加载试验研究基础之上，通过有限元分析，补充研究这类结构顶层端节点在不同水平配箍量条件下的受力性能，及梁端竖向箍筋部分进入节点区的受力性能，并对顶层端节点的水平箍筋用量，提出了设计建议。     

短肢墙无粘结预应力楼盖结构顶层端节点抗震性能试验研究

本文通过两个由短肢墙、无粘结预应力现浇板和梁组成的空间组合体结构模型的低周反复加载试验,对采取两种不同构造方案共计4个顶层端节点的受力性能、传力机理以及进入节点区梁、墙肢钢筋的实测应变分布进行了分析研究。研究结果表明,短肢墙顶层端节点上部钢筋的粘结环境很差,梁端受弯屈服后,随着反复荷载作用,充分受力的负弯矩梁筋极易在节点顶部发生粘结退化甚至粘结失效,这种梁筋粘结明显退化和失效将对组合体的整体抗震性能带来较大的不利影响;短肢墙顶层端节点的传力机理不同于普遍框架柱节点,桁架机构是这类节点的主导传力机构;在试验研究的基础上,对短肢墙顶层端节点的构造措施提出了设计建议。     

一种新的AlGaN/GaN HEMT半经验直流特性模型

在EEHEMT1模型的基础上给出一种新的A1GaN/GaN HEMT半经验直流特性模型,考虑了栅源电压对膝点电压的影响,得到描述AlGaN/GaN HEMT器件I-Ⅴ特性的方程.此模型可以应用于蓝宝石和SiC两种不同衬底AlGaN/GaN HEMT器件的I-Ⅴ特性模拟.仿真结果和实验测量结果拟合误差小于3%.     

基于剪力比的黏弹性阻尼腋撑-RC框架结构设计方法

现有减震设计方法需进行繁琐的迭代,其效率有待提高。基于剪力比的概念,采用黏弹性阻尼腋撑,设置罕遇地震下腋撑与框架结构的耗能比,提出了基于剪力比的黏弹性阻尼腋撑-RC框架结构抗震设计方法。选取7条地震动记录,根据不同剪力比 α 对6层、9层、12层模型设置不同参数的腋撑,进行罕遇地震下弹塑性动力时程分析。研究了腋撑耗能占地震输入结构总能量的关系,并将各模型最大层间位移角与GB 50011—2010《建筑抗震设计规范》的规定值进行了对比。从层间位移角、层剪力、顶层最大位移值、顶层峰值加速度等方面比较了结构的减震效果。研究结果表明：对于高40m以下的框架结构,耗能比为0.6时,剪力比 α 的合理取值范围在0.10~0.20之间;剪力比α取0.15时,RC框架结构的最大层间位移角、顶层最大位移值均减少34%~45%,层剪力、顶层加速度峰值均减少19%~23%。     

Dendrimer as nanocarrier for drug delivery

Dendrimers are novel three dimensional, hyperbranched globular nanopolymeric architectures. Attractive features like nanoscopic size, narrow polydispersity index, excellent control over molecular structure, availability of multiple functional groups at the periphery and cavities in the interior distinguish them amongst the available polymers. Applications of dendrimers in a large variety of fields have been explored. Drug delivery scientists are especially enthusiastic about possible utility of dendrimers as drug delivery tool. Terminal functionalities provide a platform for conjugation of the drug and targeting moieties. In addition, these peripheral functional groups can be employed to tailor-make the properties of dendrimers, enhancing their versatility. The present review highlights the contribution of dendrimers in the field of nanotechnology with intent to aid the researchers in exploring dendrimers in the field of drug delivery.     

钢环加固圆钢管混凝土柱-RC梁角节点轴压性能有限元分析

针对圆钢管混凝土柱-RC梁角节点,提出了对角节点的节点区采用多段钢环加固的构造方案,并对加固节点模型的轴压性能开展有限元分析研究。通过已有研究成果验证了有限元模型分析方法的可靠性,继而采用ABAQUS有限元分析软件建立152个加固节点模型进行轴压试验模拟。有限元分析结果表明,以多段钢环加强的圆钢管钢筋混凝土柱-RC梁角节点轴压性能优于普通节点,加固节点具有更高的轴压承载力和更好的延性,加固效果明显。参数分析表明：加固角节点的轴压承载力随节点混凝土轴心抗压强度、节点区钢环体积占比和节点区纵筋配筋率的增加而增加;角节点的轴压承载力受梁端剪力影响,较大的梁端剪力可能造成节点延性降低。根据分析结果,建立了节点区采用钢环加固的圆钢管约束混凝土柱-RC梁角节点的轴压承载力算式,供设计该类节点参考。