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关键词： 脑炎   抗N-甲基-D-天冬氨酸受体   扩散张量成像   认知功能  

摘要： 目的探讨抗N-甲基-D-天冬氨酸受体(NMDAR)脑炎患者的脑结构网络改变、认知障碍及其相互关系。方法本研究为回顾性研究。收集2012年9月至2019年12月在重庆医科大学附属第一医院就诊的抗NMDAR脑炎患者39例作为自身免疫性脑炎组(AE组),男16例、女23例,年龄13~66(34±15)岁,病程11~110(31±20)d。另招募常规头颅MR检查正常且既往无神经系统疾病史的32名健康志愿者作为对照组,男14名、女18名,年龄20~67(34±12)岁。对所有受检者进行扩散张量成像(DTI)并评估认知功能。采用确定性纤维追踪法构建2组脑结构网络,运用图论法分别分析2组脑结构网络全局网络拓扑属性[聚类系数(C_(p))、最短路径长度(L_(p))、局部效率(E_(loc))、全局效率(E_(glob))、标准化C_(p)(γ)、标准化L_(p)(λ)、小世界指数(σ)]和局部网络拓扑属性的差异,并进一步分析脑结构网络特征性参数与认知功能评分的相关性。结果AE组与对照组患者年龄、性别分布差异无统计学意义(P>0.05)。AE组CP值[0.005(0.004,0.007)]、γ(1.76±0.13)、λ(0.51±0.03)及σ值(1.57±0.13)与对照组[分别为0.007(0.004,0.017)、2.13±0.63、0.55±0.06、1.73±0.36]比较均下降(Z=-939.00、t=-3.58、t=-4.16、t=-2.58,P<0.05)。与对照组相比,AE组左侧眶部额中回、双侧补充运动区、左侧嗅皮质、左侧回直肌、双侧脑岛、左侧中央后回、左侧中央旁小叶及右侧颞横回节点效率改变(P<0.05)。AE组与对照组有5个相同核心节点,分别为右侧中央前回、双侧补充运动区及双侧楔前叶;AE组较对照组减少3个核心节点为左侧枕中回、左侧颞中回、右侧颞中回,增加的核心节点为左侧中央前回。AE组左侧补充运动区(r=0.393、P=0.013)、右侧补充运动区(r=0.384、P=0.016)及左侧中央旁小叶(r=0.356、P=0.026)节点效率与蒙特利尔认知评估量表评分呈正相关。结论抗NMDAR脑炎患者大脑存在广泛白质改变,部分脑区网络拓扑属性改变与认知功能下降相关。

关键词： 尿失禁   压力性   磁共振成像   扩散张量成像   尿道  

摘要： 目的探讨静态和动态盆底MRI及扩散张量成像(DTI)评估压力性尿失禁(SUI)患者尿道形态及功能的价值。方法前瞻性收集2020年7月至2021年2月郑州大学第一附属医院经临床诊断的28例女性SUI患者作为SUI组,同期选取年龄匹配的女性健康志愿者45例作为对照组。对所有受试者行静态和动态盆底MRI和DTI。在静态MRI上测量尿道中段内、外括约肌厚度和功能尿道长度(FUL),在动态最大力排相上测量FUL并计算静动态FUL差值,观察静动态MRI上是否存在膀胱颈漏斗征及尿道开放征。对DTI原始图像进行后处理获得尿道括约肌复合体肌纤维束图像,观察图像并测量尿道中段环形括约肌、中央纵行肌肌纤维的各向异性分数(FA)、表观扩散系数(ADC)及3个特征值(λ1,λ2,λ3)。采用独立样本t检验比较SUI组与对照组间静态和动态MRI测量值、DTI参数的差异,采用χ^(2)检验比较2组MRI征象的差异。结果SUI组尿道中段外括约肌厚度、静态及动态FUL均小于对照组(t=-3.95、-5.72、-8.41,P均<0.001);SUI组静动态FUL差值大于对照组(t=4.41,P<0.001);SUI组静动态膀胱颈漏斗征及动态尿道开放征出现率高于对照组(χ^(2)=23.09、22.25、26.59,P均<0.001)。SUI组尿道中段环形括约肌FA值小于对照组(t=-3.48,P=0.001),ADC、λ2、λ3值大于对照组(t=3.19、2.15、2.06,P=0.002、0.038、0.046);2组间尿道中段纵行肌DTI各参数差异均无统计学意义(P均>0.05)。结论静态和动态MRI及DTI能够客观评估SUI患者尿道形态和功能的变化,尿道中段外括约肌厚度变薄,FUL缩短及环形括约肌纤维束微结构被破坏是SUI患者尿道的主要变化。

关键词： 冬雨   高考成绩   期末考试   担心  

摘要： 问:期末考试满分750分,我闺女考了321分。我忧心如焚,她却毫不担心,还问我,知道周冬雨吗?我说知道,怎么了?她说,周冬雨长相一般,高考成绩不足300分,这都能成功,那我又有什么可担心的呢?我被闺女的“蜜汁自信”惊呆了。请问,我该如何教育她?

关键词： 预埋光纤光栅传感器   碳纤维复合材料螺旋桨   动应变   水下在线测试  

摘要： [目的]碳纤维复合材料(CFRP)螺旋桨具有轻质高强、低振动、低噪音、耐腐蚀、抗疲劳等优势。为了准确获知CFRP螺旋桨桨叶在水动力载荷下的变形和应变,提出一种水下运转状态下CFRP螺旋桨动应变在线测试方法。[方法]将光纤光栅(FBG)传感器预埋于CFRP螺旋桨,搭建CFRP螺旋桨水下动应变测试系统,设置2类测试工况:进速为0 m/s,转速从50~400 r/min依次增加;转速保持427 r/min不变,进速从0~1.6 m/s依次增加。通过FBG传感器采集上述2类工况下CFRP螺旋桨的动应变数据,对动应变数据进行时域和频谱分析。[结果]结果表明,CFRP螺旋桨上各测点的动应变特征频率一致,且与转速相关;各测点的动应变峰值取决于测点位置,即螺旋桨的结构力学特征。[结论]实现了CFRP螺旋桨在水下运转状态下的动应变在线测试,测试结果合理可靠,可为CFRP螺旋桨的理论设计和分析提供重要的实证依据,对研究螺旋桨振动噪声和水动力性能具有重要意义。

关键词： 光栅   温湿度   光谱曲线   高斯拟合   光谱面积  

摘要： 相比传统监测手段,光纤传感器具有灵敏度高、本质绝缘性高、抗电磁干扰能力强等优势,但基于光纤布拉格光栅的湿度传感器易受温度和应力影响,存在湿度测量误差大、稳定性差等问题。针对这些问题,提出了一种单光栅半涂覆温湿度传感器的制备方法。首先,在光栅的一半栅区上涂覆湿敏材料,另外一半栅区为裸光栅。然后,对裸光栅的反射光谱峰值曲线进行高斯拟合,建立环境温度与中心波长λ的函数关系。最后,分析了光栅反射光谱曲线和峰值功率围成的面积S与不同环境湿度的关系,建立面积S与环境相对湿度的函数模型,并采用温湿度发生器对传感器进行测试。实验结果表明,在10%RH~90%RH(%RH为相对湿度)范围内,该传感器具有较好的重复性,湿度监测灵敏度为2.95/%RH,响应时间为6.6 min,满足仓储等行业对温湿度的监测需求,为相关领域的温湿度监测提供了一种新的解决方案。

关键词： 薄膜   太阳能电池   时域有限差分法   光捕获   半圆形光栅   梯形光栅   短路电流密度  

摘要： 设计了一种半圆形前置与梯形后置双界面的光栅结构的单晶硅薄膜太阳能电池,利用时域有限差分法对该结构和对照组进行了模拟计算,通过分析短路电流密度和吸收光谱可知,双界面光栅结构的光捕获性能优于单界面光栅结构,利用电磁场分布对该结构在长波段(750~1100 nm)的吸收增强机理进行了分析。此外,针对前置半圆形后置梯形光栅结构,进一步优化了后置梯形光栅的左右斜率与同周期下前后光栅的偏移程度,结果表明非规则的梯形结构具有较好的光捕获表现,通过吸收效率云图也能发现偏移程度在40 nm时效果最佳。通过计算分析,短路电流密度的最优值达到了20.17 mA/cm^(2),相较于平板结构的短路电流密度提高了58.1%,研究结果对于薄膜太阳能电池的光栅结构设计具有一定的指导意义。

关键词： aerosol   assimilation   air quality   aerosol optical depth   pre-operational system   MODIS  

摘要： In this study we present a pre-operational forecasting assimilation system of different types of aerosols. This system has been developed within the chemistry-transport model of Meteo-France, MOCAGE, and uses the assimilation of the Aerosol Optical Depth (AOD) from MODIS (Moderate Resolution Imaging Spectroradiometer) onboard both Terra and Aqua. It is based on the AOD assimilation system within the MOCAGE model. It operates on a daily basis with a global configuration of 1 degrees x1 degrees (longitude x latitude). The motivation of such a development is the capability to predict and anticipate extreme events and their impacts on the air quality and the aviation safety in the case of a huge volcanic eruption. The validation of the pre-operational system outputs has been done in terms of AOD compared against the global AERONET observations within two complete years (January 2018-December 2019). The comparison between both datasets shows that the correlation between the MODIS assimilated outputs and AERONET over the whole period of study is 0.77, whereas the biases and the RMSE (Root Mean Square Error) are 0.006 and 0.135, respectively. The ability of the pre-operational system to predict extreme events in near real time such as the desert dust transport and the propagation of the biomass burning was tested and evaluated. We particularly presented and documented the desert dust outbreak which occurred over Greece in late March 2018 as well as the wildfire event which happened on Australia between July 2019 and February 2020. We only presented these two events, but globally the assimilation chain has shown that it is capable of predicting desert dust events and biomass burning aerosols which happen all over the globe.

关键词： Surgical Oncology   Oncology   Surgery  

关键词： CO   (2)-reduction reaction   electrochemistry   Fe   N   C-Catalysts   in situ spectroscopy   O   (2) reduction reaction   platinum group metal-free  

摘要： To advance the widespread implementation of electrochemical energy storage and conversion technologies, the development of inexpensive electrocatalysts is imperative. In this context, Fe/N/C-materials represent a promising alternative to the costly noble metals currently used to catalyze the oxygen reduction reaction (ORR), and also display encouraging activities for the reduction of CO2. Nevertheless, the application of these materials in commercial devices requires further improvements in their performance and stability that are currently hindered by a lack of understanding of the nature of their active sites and the associated catalytic mechanisms. With this motivation, herein the authors exploit the high sensitivity of modulation excitation X-ray absorption spectroscopy toward species undergoing potential-induced changes to elucidate the operando local geometry of the active sites in two sorts of Fe/N/C-catalysts. While the ligand environment of a part of both materials' sites appears to change from six-/five- to fourfold coordination upon potential decrease, they differ substantially when it comes to the geometry of the coordination sphere, with the more ORR-active material undergoing more pronounced restructuring. Furthermore, these time-resolved spectroscopic measurements yield unprecedented insights into the kinetics of Fe-based molecular sites' structural reorganization, identifying the oxidation of iron as a rate-limiting process for the less ORR-active catalyst.

关键词： Saturable absorbers  

摘要： Platinum ditelluride (PtTe2) has many applications in phototransistors, photodetectors, photocatalysis and other fields due to its interesting semiconductor-to-semimetal transition property, ultrashort excited carrier lifetime, high carrier mobility, excellent air stability, and so on. However, the ultrafast nonlinear optical properties of PtTe2 and its application in ultrafast photonics have been rarely explored so far. In this work, PtTe2 nanosheets were prepared and two kinds of saturable absorbers (SAs) were further fabricated, namely the PtTe2/PVA film and PtTe2 coated tapered fiber. The results showed different nonlinear absorption properties for the two SAs. The modulation depth and saturation intensity were determined to be 0.9% and 55.7 MW cm(-2) for the PVA film, and 8.9% and 1.39 GW cm(-2) for the tapered fiber, respectively. More importantly, Q-switched and mode-locked Er-doped fiber lasers were realized using the PtTe2/PVA film and PtTe2 coated tapered fiber SAs, respectively. The pulse widths of the Q-switched and mode-locked fiber lasers are 2.63 mu s and 959 fs, respectively. These results confirm that PtTe2 has great potential in ultrafast photonic applications, and moreover, the PtTe2 coated tapered fiber SA is more suitable for mode-locked fiber lasers because of its lower nonsaturable absorption loss and larger modulation depth by contrast to the PVA film SA.