Nonlinear inversion of ultrasonic guided waves for in vivo evaluation of cortical bone properties

Ultrasonic guided waves (UGWs), which propagate throughout the entire thickness of cortical bone, are attractive for the early diagnosis of osteoporosis. However, this is challenging due to the impact of soft tissue and the inherent difficulties related to multiparametric inversion of cortical bone quality factors, such as cortical thickness and bulk wave velocity. Therefore, in this research, a UGW-based multi-parameter inversion algorithm is developed to predict strength-related factors. In simulation, a free plate (cortical bone) and a bilayer plate (soft tissue and cortical bone) are used to validate the proposed method. The inversed cortical thickness (CTh), longitudinal velocity (V_L) and transverse velocity (V_T) are in accordance with the true values. Then four bovine cortical bone plates were used in in vitro experiments. Compared with the reference values, the relative errors for cortical thickness were 3.96%, 0.83%, 2.87%, and 4.25%, respectively. In the in vivo measurements, UGWs are collected from the tibias of 10 volunteers. The theoretical dispersion curves depicted by the estimated parameters (V_T, V_L, CTh) match well with the extracted experimental ones. In comparison with dual-energy x-ray absorptiometry, our results show that the estimated transverse velocity and cortical thickness are highly sensitive to osteoporosis. Therefore, these two parameters (CTh and V_T) of long bones have potential to be used for diagnosis of bone status in clinical applications.     

Amplitude modulation excitation for cancellous bone evaluation using a portable ultrasonic backscatter instrumentation

The ultrasonic backscatter (UB) has the advantage of non-invasively obtaining bone density and structure, expected to be an assessment tool for early diagnosis osteoporosis. All former UB measurements were based on exciting a short single-pulse and analyzing the ultrasonic signals backscattered in bone. This study aims to examine amplitude modulation (AM) ultrasonic excitation with UB measurements for predicting bone characteristics. The AM multiple lengths excitation and backscatter measurement (AM-UB) functions were integrated into a portable ultrasonic instrument for bone characterization. The apparent integrated backscatter coefficient in the AM excitation (AIB_AM) was evaluated on the AM-UB instrumentation. The correlation coefficients of the AIB_AM estimating volume fraction (BV/TV), structure model index (SMI), and bone mineral density (BMD) were then analyzed. Significant correlations (|R| = 0.82-0.93, p < 0.05) were observed between the AIB_AM, BV/TV, SMI, and BMD. By growing the AM excitation length, the AIB_AM values exhibit more stability both in 1.0-MHz and 3.5-MHz measurements. The recommendations in AM-UB measurement were that the avoided length (T1) should be lower than AM excitation length, and the analysis length (T2) should be enough long but not more than AM excitation length. The authors conducted an AM-UB measurement for cancellous bone characterization. Increasing the AM excitation length could substantially enhance AIB_AM values stability with varying analyzed signals. The study suggests the portable AM-UB instrument with the integration of real-time analytics software that might provide a potential tool for osteoporosis early screening.     

基于CC2531的安全监测预警系统设计

为解决目前基层军营安全监测手段存在的高功耗、高成本、实时性较差、易被破坏等问题,选用CC2531和CC2591作为ZigBee通信模块芯片,布设多种传感器,搭建无线传感网,以PC机为监测主机,制定通信协议,设计出军营无线安全监测与预警系统;实现一平方公里范围内温度、湿度、人体入侵、可燃气体烟雾浓度等信息的远程监测与自动预警;以不同距离监测哈尔滨十二月份室外温度、相对湿度为试验,无数据丢失,温湿度测量误差不大于2%,表明系统具有高可靠性、高精度、低功耗、灵活易用等优点,具有广阔的应用前景。     

利用软X射线双频光栅剪切干涉技术诊断金等离子体

激光辐照靶产生的等离子体电子密度的诊断对于惯性约束聚变、等离子体物理、高能量密度物理等相关领域的研究具有重要意义,特别是中、高Z材料等离子体临界面附近的电子密度分布信息的测量.采用波长13.9 nm的类镍银软X射线激光作为探针,利用双频光栅剪切干涉技术尝试诊断了激光辐照金平面靶产生的等离子体的电子密度分布.实验获得了清晰的干涉条纹图像,通过对条纹的初步处理,测量到的最高密度达到了约1.4倍临界密度.通过与相关理论程序模拟结果对比,发现实验与模拟存在一定的偏差,为进一步优化模拟程序提供了有益的参考.通过实验,充分表明了软X射线激光双频光栅干涉技术在诊断中、高Z材料临界密度附近区域等离子体方面的实用性.     

内插直线型转子的管内流动与换热实验研究

实验研究了内插不同结构参数直线型转子的管内流动阻力和传热特性,结果表明,由于中空的结构形式,直线型转子可增大壁面处流体速度梯度,增强扰动,从而在阻力增加不大的条件下,实现强化换热和除垢抑垢。减小螺旋叶片角度、优化直线段形状、设置凸起等方式有助于提高内插转子的管内综合换热性能,三正三反交替布置为较优的转子排列方式。     

基于稳定子码的在噪声信道的量子安全直接通信方案研究

量子安全直接通信是继量子密钥分配后,量子通信领域又一重要的研究领域,它要求通信双方在预先不需要建立共享密钥的情况下就可以实现消息的保密传输。不同于属于非确定通信的量子密钥分配,量子直接通信受信道噪声的影响更大,需要更好的检错纠错能力。本文根据稳定子码纠错理论和GHZ三态纠缠粒子的特性提出了一套基于稳定子码理论的量子直接通信方案,使其在保持无条件安全性的基础上可以对单量子的相位和比特错误进行纠错检错,大大降低了信道的整个通信过程的量子比特错误率。     

核酸适配体功能化近红外量子点结合流式细胞术快速检测白血病细胞

利用作为肿瘤细胞识别分子的核酸适配体(Aptamer)的高特异性和高亲和力以及作为信号报告单元的近红外量子点(QDs)的高荧光发射强度和低生物背景干扰特性,构建了一种基于Aptamer功能化近红外QDs的新型纳米荧光探针,并进一步结合流式细胞术在单细胞荧光分析方面的高通量、简便和快速等优势,建立了一种检测白血病细胞的新方法.以基于Cell-SELEX(Cell-based systematic evolution of ligands by exponential enrichment)技术针对CCRF-CEM人急性白血病细胞筛选的特异性Aptamer Sgc8c为模型,构建了Sgc8c-QDs探针,其仅需与细胞样品培育30 min即可实现对缓冲液和血清中靶细胞的简单、快速和高特异性检测.与传统荧光染料标记技术相比,该方法不仅大大提高了分析灵敏度,还显示出对血清等复杂生物样品的高适用性和优良检测性能.鉴于Cell-SELEX技术在其它白血病细胞Aptamer筛选领域的应用潜力,该方法有望作为一种通用技术在白血病诊断及预后监测等方面发挥重要作用.     

高速逆流色谱分离制备马比木中的三个喜树碱类成分

采用高速逆流色谱技术从马比木粗提物中快速分离制备喜树碱类化学成分。通过高效液相色谱测定各溶剂系统的分配系数,获得较好的分离条件。溶剂体系为:V(氯仿):V(正己烷):V(甲醇):V(水)=6:6:5:4,上相(水相)为固定相,下相(有机相)为流动相,正相洗脱;进样质量浓度:2.25 mg/mL;进样体积:20 mL;流速:2.0 mL/min;转速:800 r/min,从马比木粗提物中一次分离制备出3种单体成分。其结构经HPLC,UV,IR,ESI-MS和NMR确认和分析,分别为10-羟基脱氧喜树碱(1)、10-甲氧基喜树碱(2)和喜树碱(3),纯度分别为98.3%,99.3%,99.0%。