Effect of Microwave-Assisted Synthesis and Sintering of Lead-Free KNL-NTS Ceramics

Lead-free piezoelectric powders (K_0.44Na_0.52Li_0.04)(Nb_0.82Ta_0.10Sb_0.04)O₃ were obtained by conventional and microwave-assisted reactive heating. Firstly, the synthesis of the material was carried out following the mixed oxide route and employing both traditional methods and microwave technology. Thermogravimetry, X-ray diffraction, field emission scanning electron microscopy and electrical properties analyses were evaluated. X-ray diffraction of the powders calcined by the microwave process shows the formation of perovskite structure with orthorhombic geometry, but it is possible to observe the presence of other phases. The presence of the secondary phases found can have a great influence on the heating rate during the synthesis on which the kinetics of the reaction of formation of the piezoelectric compound depend. The calcined powder was sintered at different temperatures by conventional and non-conventional processes. The microstructure of the ceramics sintered by microwave at 1050 °C for 10 min shows perovskite cubes with regular geometry, of size close to 2–5 µm. However, the observed porosity (~8%), the presence of liquid phase and secondary phases in the microstructure of the microwave sintered materials lead to a decrease of the piezoelectric constant. The highest d₃₃ value of 146 pC/N was obtained for samples obtained by conventional at 1100 °C 2 h compared to samples sintered by microwave at 1050 °C 10 min (~15 pC/N).     

Sleep-Specific Processing of Auditory Stimuli Is Reflected by Alpha and Sigma Oscillations

Recent research revealed a surprisingly large range of cognitive operations to be preserved during sleep in humans. The new challenge is therefore to understand functions and mechanisms of processes, which so far have been mainly investigated in awake subjects. The current study focuses on dynamic changes of brain oscillations and connectivity patterns in response to environmental stimulation during non-REM sleep. Our results indicate that aurally presented names were processed and neuronally differentiated across the wake-sleep spectrum. Simultaneously recorded EEG and MEG signals revealed two distinct clusters of oscillatory power increase in response to the stimuli: (1) vigilance state-independent θ synchronization occurring immediately after stimulus onset, followed by (2) sleep-specific α/σ synchronization peaking after stimulus offset. We discuss the possible role of θ, α, and σ oscillations during non-REM sleep, and work toward a unified theory of brain rhythms and their functions during sleep.SIGNIFICANCE STATEMENT Previous research has revealed (residual) capacity of the sleeping human brain to interact with the environment. How sensory processing is realized by the neural assemblies in different stages of sleep is however unclear. To tackle this question, we examined simultaneously recorded MEG and EEG data. We discuss the possible role of θ, α, and σ oscillations during non-REM sleep. In contrast to versatile θ band response that reflected early stimulus processing step, succeeding α and σ band activity was sensitive to the saliency of the incoming information, and contingent on the sleep stage. Our findings suggest that the specific reorganization of mechanisms involved in later stages of sensory processing takes place upon falling asleep.     

光电技术在黄褐斑治疗中的应用

黄褐斑是一种好发于女性面部的色素增加性皮肤病,治疗是目前的难点,成功率较低,而复发率较高。近年来,光电技术治疗黄褐斑在国内外取得了满意疗效,主要包括强脉冲光、Q开关激光、点阵激光、皮秒激光、脉冲染料激光、射频技术等。其中强脉冲光、Q开关激光、皮秒激光治疗黄褐斑的疗效及安全性得到了广泛认可,其他光电技术的疗效及安全性还有待于进一步研究。本文就光电技术在黄褐斑治疗中的应用作一综述。     

中药薄层色谱影响因素分析及应用

该文分析了对薄层色谱有较大影响的温度、湿度等因素,探讨解决方案,并举例说明.薄层色谱的影响因素较多,但薄层色谱法仍是中药分析中广泛应用的经典方法.随着薄层板、点样技术、展开技术、检视技术等方面的发展,薄层色谱的规范化,操作仪器化程度的提高,加之其简单、便捷、经济、灵敏、高效,薄层色谱法必将在中药及其制剂的质量控制及检验中发挥越来越大的作用.     

Thresholding Methods for Reduction in Data Processing Errors in the Laser-Textured Surface Topography Measurements

There are many factors influencing the accuracy of surface topography measurement results: one of them is the vibrations caused by the high-frequency noise occurrence. It is extremely difficult to extract results defined as noise from the real measured data, especially the application of various methods requiring skilled users and, additionally, the improper use of software may cause errors in the data processing. Accordingly, various thresholding methods for the minimization of errors in the raw surface topography data processing were proposed and compared with commonly used (available in the commercial software) techniques. Applied procedures were used for the minimization of errors in the surface topography parameters (from ISO 25178 standard) calculation after the removal and reduction, respectively, of the high-frequency noise (S-filter). Methods were applied for analysis of the laser-textured surfaces with a comparison of many regular methods, proposed previously in the commercial measuring equipment. It was found that the application of commonly used algorithms can be suitable for the processing of the measured data when selected procedures are provided. Moreover, errors in both the measurement process and the data processing can be reduced when thresholding methods support regular algorithms and procedures. From applied, commonly used methods (regular Gaussian regression filter, robust Gaussian regression filter, spline filter and fast Fourier transform filter), the most encouraging results were obtained for high-frequency noise reduction in laser-textured details when the fast Fourier transform filter was supported by a thresholding approach.     

The impact of depression on mothers’ neural processing of their adolescents’ affective behavior

Depression affects neural processing of emotional stimuli and could, therefore, impact parent–child interactions. However, the neural processes with which mothers with depression process their adolescents’ affective interpersonal signals and how this relates to mothers’ parenting behavior are poorly understood. Mothers with and without depression (N = 64 and N = 51, respectively; M_age = 40 years) from low-income families completed an interaction task with their adolescents (M_age = 12.8 years), which was coded for both individuals’ aggressive, dysphoric, positive and neutral affective behavior. While undergoing fMRI, mothers viewed video clips from this task of affective behavior from their own and an unfamiliar adolescent. Relative to non-depressed mothers, those with depression showed more aggressive and less positive affective behavior during the interaction task and more activation in the bilateral insula, superior temporal gyrus and striatum but less in the lateral prefrontal cortex while viewing aggressive and neutral affect. Findings were comparable for own and unfamiliar adolescents’ affect. Heightened limbic, striatal and sensory responses were associated with more aggressive and dysphoric parenting behavior during the interactions, while reduced lateral prefrontal activation was associated with less positive parenting behavior. These results highlight the importance of depressed mothers’ affective information processing for understanding mothers’ behavior during interactions with their adolescents.     

Analytical Model for Early Design Stage of Cable-Stayed Suspension Bridges Based on Hellinger–Reissner Variational Method

The cable-stayed suspension bridge is one type of bridge that has been increasingly applied to bridge engineering, especially in cross-sea projects. However, the complex combined system of this type of bridge makes it quite difficult for researchers to make a quick decision of the parameter values during the design stage. The Hellinger–Reissner method is applied here to analyze the deformation and force of the structural members in the bridge. The advantage of this method is that the solving of deformation and force is independent of each other, which would enhance the accuracy of the final results. Different load conditions are also considered in the analysis. The results from the present method are compared with test results and finite element analysis, and show good agreements. It implies that the Hellinger–Reissner is a comparatively more efficient method to help designers choose the key parameters for cable-stayed suspension bridges.     

细胞检测的一种数学形态学方法

本文介绍一种利用数学形态学中顶帽变换来检测显微照片中细胞的方法,并设计了确定细胞区域的算法。这种方法运算简单、效果好,并行程度高,优于传统的细胞检出算法。     

CT时间减影技术在肺结节检测中的应用

目的 探讨CT时间减影技术在检测肺结节中的应用价值.方法 回顾性分析80例CT图像(每例均有过去和当前的CT图像)和相应的CT减影图像,其中30例有肺结节(共75个结节)作为研究组,50例无肺结节作为对照组.2名高年资与2名低年资放射科医师分别首先分析普通CT图像,然后再同时分析普通图像与CT减影图像.阅读时诊断是否存在较前次增大、实性成分增多或者新发的结节并对诊断的肯定度进行评分.观察的结果采用受试者工作特征(ROC)曲线进行分析.结果 4名放射科医师使用CT减影图像前后的平均ROC曲线下面积(AUC)分别为0.860和0.925,两者有统计学差异(P<0.01).使用CT减影图像后,肺结节检出率由77.3%(58/75)提高到89.3%(67/75).结论 CT时间减影技术可以显著提高放射科医师的肺结节检出率,尤其是对靠近肺门的亚实性小结节,而且低年资医师受益更多.     

基于“3面9点”配准方案的PET+MRI异机二维图像融合尝试

目的:尝试一种基于体表定位的二维图像配准方法,实现PET和MRI异机图像的精确融合。方法:输入PET/MRI原始数据后采用数字化格式转换,设计"3面9点"立体定位法进行配准,在实时工作站Mimics按照信息交互自动融合模式,通过讯号叠加技术完成图像融合。结果:以肺癌患者的胸部和髋部为实例交叉试验PET+MRI二维图像的异机融合,生成同时呈现胸髋解剖结构和代谢状况的互补影像。结论:在同机设备成本昂贵、不易普及的条件下,这种异机融合无疑是现有同机成像的必要补充。