电子束辐照对Poly-SiO_2/Si结构平带电压的影响

利用剂量为 10 13 cm～ 10 16 cm- 2 ,能量为 0 .4Mev～ 1.8Mev的电子束辐照Poly -SiO2 Si结构 ,对辐照后样品进行了C -V特性曲线测试 .测试结果表明 ,高能电子束辐照Poly -SiO2 Si结构引起的MOS电容平带电压随辐照剂量、能量的增加而发生漂移 ,但其漂移量低于同一实验环境中干氧氧化生长的SiO2 Si结构     

新型铁电复合材料ATGS-PVDF受γ辐射效应的研究

本文研究了新型铁电复合材料ATGS-PVDF受γ辐射效应.实验发现当吸收一定累积辐射剂量后,复合材料的体电阻ρ、电容率ε、纯热释电系数P和热电驰豫时间τ都将发生变化.还发现对于此复合材料存在两个累积辐射剂量的数值界限R1和R2.当累积辐射剂量小于或接近R1时,复合材料的ρ、ε、P和τ的变化趋势与自然老化规律基本相同;当累积辐射剂量达到或超过R2后,复合材料将产生永久损伤.本文从理论上分析了γ辐射的电离效应在复合材料中产生的正负电离电荷和局域辐射势阱是复合材料产生上述辐射效应的主要原因.     

Acute moderate exercise does not attenuate cardiometabolic function associated with a bout of prolonged sitting

Epidemiological studies suggest that prolonged sitting increases all-cause mortality; yet, physiological causes underpinning prolonged sitting remain elusive. We evaluated cardiometabolic function during prolonged sitting (5 h) in 10 adults with and without 30 min of moderate exercise leading up to the sitting. Mean arterial blood pressure (MAP), heart rate (HR) and posterior tibial artery blood velocity were measured at baseline and every hour subsequently. Blood glucose was measured at baseline, 3 and 5 h, with consumption of a caloric beverage at 1 h. Seated MAP and HR values were ~17 mmHg (P < 0.001) and ~4 bpm (P < 0.05) higher for the moderate exercise versus sitting conditions. A ~ 4 cm·s^?1 (16%) (P < 0.05) decline in posterior tibial artery blood velocity from prolonged sitting was observed, with no benefit conferred from moderate exercise. Postprandial glucose metabolism was not different between conditions (P > 0.05). We conclude prolonged sitting may be related to decreased posterior tibial artery blood velocity. Moreover, an acute bout of moderate exercise does not seem to attenuate cardiometabolic function during prolonged sitting in healthy, young adults.     

Ultrasound imaging in medical student education: Impact on learning anatomy and physical diagnosis

Ultrasound use has expanded dramatically among the medical specialties for diagnostic and interventional purposes, due to its affordability, portability, and practicality. This imaging modality, which permits real‐time visualization of anatomic structures and relationships in vivo, holds potential for pre‐clinical instruction of students in anatomy and physical diagnosis, as well as providing a bridge to the eventual use of bedside ultrasound by clinicians to assess patients and guide invasive procedures. In many studies, but not all, improved understanding of anatomy has been demonstrated, and in others, improved accuracy in selected aspects of physical diagnosis is evident. Most students have expressed a highly favorable impression of this technology for anatomy education when surveyed. Logistic issues or obstacles to the integration of ultrasound imaging into anatomy teaching appear to be readily overcome. The enthusiasm of students and anatomists for teaching with ultrasound has led to widespread implementation of ultrasound‐based teaching initiatives in medical schools the world over, including some with integration throughout the entire curriculum; a trend that likely will continue to grow. Anat Sci Educ 10: 176–189. © 2016 American Association of Anatomists.     

柚皮、豆渣、杭白菊的超声提取物抗氧化性能比较研究

以杭白菊、柚皮、豆渣的超声提取物为研究对象,通过油脂氧化实验和清除羟自由基作用体系,分析比较了三者的抗氧化能力,并且分别以柠檬酸和抗坏血酸为添加剂进一步研究了其增效作用,结果显示抗坏血酸的增效作用较为明显.     

微波辐射SnCl_4·5H_2O催化环己醇脱水制环己烯

研究了在微波辐射条件下,SnCl4 5H2O催化环己醇脱水制环己烯的反应。考察了催化利用量,微波辐射时间和功率对反应的影响。结果表明:在催化剂用量为2g,环己醇用量为10mL,微波辐射功率为600W,辐射时间为10min时,环己烯收率达68.4％。     

Improved medical student perception of ultrasound using a paired anatomy teaching assistant and clinician teaching model

This study describes a new teaching model for ultrasound (US) training, and evaluates its effect on medical student attitudes toward US. First year medical students participated in hands‐on US during human gross anatomy (2014 N = 183; 2015 N = 182). The sessions were facilitated by clinicians alone in 2014, and by anatomy teaching assistant (TA)‐clinician pairs in 2015. Both cohorts completed course evaluations which included five US‐related items on a four‐point scale; cohort responses were compared using Mann‐Whitney U tests with significance threshold set at 0.05. The 2015 survey also evaluated the TAs (three items, five‐point scale). With the adoption of the TA‐clinician teaching model, student ratings increased significantly for four out of five US‐items: “US advanced my ability to learn anatomy” increased from 2.91 ± 0.77 to 3.35 ± 0.68 (P < 0.0001), “Incorporating US increased my interest in anatomy” from 3.05 ± 0.84 to 3.50 ± 0.71 (P < 0.0001), “US is relevant to my current educational needs” from 3.36 ± 0.63 to 3.54 ± 0.53 (P = 0.015), and “US training should start in Phase I” from 3.36 ± 0.71 to 3.56 ± 0.59 (P = 0.010). Moreover, more than 84% of students reported that TAs enhanced their understanding of anatomy (mean 4.18 ± 0.86), were a valuable part of US training (mean 4.23 ± 0.89), and deemed the TAs proficient in US (mean 4.24 ± 0.86). By using an anatomy TA‐clinician teaching team, this study demonstrated significant improvements in student perceptions of the impact of US on anatomy education and the relevancy of US training to the early stages of medical education. Anat Sci Educ 11: 175–184. © 2017 American Association of Anatomists.     

超声波抑制积垢的影响因素与作用原理的研究

通过静态抑垢实验,研究了积垢溶液中[Ca2+]和[Mg2+]总浓度,溶液的pH值对超声抑垢的影响,得出超声抑垢的适宜条件;引进抑垢曲线新概念,直观地描述超声抑垢的效果,并从抑垢静态、动态实验得到验证;同时研究了超声波对溶液的电导率,表面张力的影响.最后,探讨了超声波的抑垢机理,为超声防垢的实际应用提供一定的理论依据.     

核技术与农业

核技术是农业科学研究的有力工具，核技术农业应用是农业科学和 农业生产中的 一项高新技术,是非核动力应用中的一个重要的方面，也是核技术应用中一个卓有成效的科 学 领域。核技术农业应用涉及许多基础理论、方法学和应用技术及工艺等一系列问题，在具 体应用中需要不断研究创新才能发挥其作用。由于我国在过去的数十年间重视了上述各方面 的研究，核技术对我国农业科学和农业生产的发展起了重大的推动作用，其研究成果的应用 产生了巨大的经济效益、社会效益和生态效益。本文简要回顾了我国核技术农业应用研究的 巨大成就和发展现状，也列举了面临的困难，并呼吁政府和科技管理部门予以重视和支持， 以使其继续发展，为国家、为“三农”、为全面建设小康社会作出贡献。     

Single-frequency matching pursuits based time-of-flight measurement in viscoacoustic medium

Broadband ultrasound signals will produce distortion in viscoacoustic medium, which may influence the accuracy of time-of-flight (TOF) measurement. Under the condition of single-frequency acoustic source, the wave propagation process in viscoacoustic medium was analyzed and an approximate solution of the wave propagation was given. Instances of broadband ultrasound were analyzed and simulated based on the single-frequency results. A single-frequency matching pursuits (SFMP) algorithm was then introduced to solve the waveform distortion problem. Time-frequency decomposition was applied to extracting the single-frequency compositions from broadband ultrasound signals, and then these compositions were sent to the matching pursuits (MP) algorithm for calculating the TOF parameters. Compared with the broadband signals, the shapes of extracted single-frequency signals change more slightly as distance and attenuation coefficient increase. The residuals of SFMP were far less than those of MP algorithm. Experimental results show that the SFMP algorithm is able to eliminate waveform distortion of broadband ultrasound in viscoacoustic medium, which helps improve the accuracy of TOF measurement.