Detecting MoS2 and MoSe2 with optical contrast simulation

Optical imaging is a promising method to identify and locate 2D materials efficiently and non-invasively. By putting a 2D material on a substrate, the nanolayer will add to an optical path and create a contrast to the case when the nanolayer is absent. This optical contrast imaging can be used to identify the 2D material and its number of layers. To make the optical imaging process in the laboratories an effective tool, Fresnel Law as a model was used to simulate the optical imaging results of 2D materials(graphene, Mo S2 and MoSe_2) on top of different thickness of SiO_2 and Si wafer in the present investigation. The results provide the details of the optimal conditions(optimal light wavelength and optimal SiO_2 thickness) to identify and locate single to few 2D nanolayers, which can be used directly in laboratories. The optical contrasts of 1–5 layers of molybdenum disulfide(MoS_2) and molybdenum diselenide(MoSe_2) were simulated. To the best of our knowledge, it is the first time that the optical contrast results of MoSe_2 have been reported. In particular, this work highlights the sensitivity of the model on the accuracy of the refractive indices used. It is demonstrated that through computational modeling that optical contrast can allow effective determination of number of layers in few layer 2D materials.     

Secure pairing with wearable devices by using ambient sound and light

Wearable devices usually work together with smart phones. To ensure only legitimate smart phones can read the data, they must conduct pairing to establish a shared key. Traditional pairing methods require that the pairing devices have a keyboard or screen for user interaction. However, due to the size limitation, keyboards or screens are hard to be installed in the wearable devices. To solve this problem, we propose a novel pairing method by using ambient sound and light. In this new scheme, any pairing request from smart phone will trigger wearable device vibration. Only after users press the confirm key on the device can the pairing process continues. Then pairing devices collect ambient sound and light at the predetermined time and establish a shared key by using the Diffie-Hellman protocol. To protect against potential man-in-the-middle attacks in the key establishment process, an improved interlock protocol with sound and light comparison is conducted to authenticate the key. If both the sound and light collected by the pairing devices are similar enough, the key is accepted. Otherwise, it is rejected. Compared with current context based pairing methods, our scheme does not impose strict synchronization on devices to collect ambient context data. Moreover, our scheme need not collect and exchange contextual information for multiple times to resist offline brute force attacks. The experimental results and security analysis prove the effectiveness of our scheme.     

UPLC-MS/MS法同时检测小花鬼针草中6种单体成分的含量

建立了一种应用UPLC-MS/MS同时测定小花鬼针草中6种单体成分原儿茶酸、芦丁、金丝桃苷、槲皮苷、槲皮素和山奈酚含量的方法。小花鬼针草药材粉碎后，经甲醇超声提取稀释后进样，采用负离子多反应监测（MRM）模式同时测定提取物中6种单体成分的含量，并以芍药苷为内标。色谱柱为Agilent SB C18 （50 mm × 2.1 mm, 1.8 μm），流动相为乙腈-0.1%甲酸水溶液，梯度洗脱，流速为0.4 mL/min，柱温为35 ℃。结果表明，该方法所测6种成分在相应的质量浓度范围内，峰面积与浓度线性关系良好，r＞0.999 0；平均加样回收率（n=6）为92.1% ～95.5%，相对标准偏差≤4.50%。该方法简单快捷、灵敏度高、专属性强，可同时测定小花鬼针草中6种单体成分。     

非线性光机械系统中的弱力探测

从理论上研究了包含光学参量放大器的非线性腔光机械系统的弱力探测性能.一方面,发现通过调节光学参量放大器的非线性增益以及输入光场与腔场之间的有效失谐,可以减小压缩正交中约14 dB的量子噪声,从而将弱力探测灵敏度提高2倍以上.另一方面,分析了非线性腔结合零差测量产生的反作用噪声相消现象并且实现量子非破坏测量的方法.     

医疗卫生工作者心理健康水平现状

 为了解医疗卫生工作者心理健康水平的现状，从2017年科技工作者心理状况调查的数据中选取医疗卫生工作者样本1463人，同时抽取其他科技工作者1441人作为对照组。调查结果发现：医疗卫生工作者抑郁风险低于对照组，焦虑和自杀意念与对照组无显著差异，工作倦怠及情感衰竭度显著高于对照组；医疗卫生工作者心理健康群体差异明显，50岁后抑郁和焦虑水平均降低，正高级职称人群的抑郁和焦虑水平均较低。情绪调控方式上，压制组表现出更多的抑郁和焦虑风险；同时，医疗卫生工作者存在睡眠时间不足、运动次数和运动时长不足、工作时长过长的问题；在心理健康服务方面，医疗卫生工作者整体优于对照组。建议改善医疗卫生工作者工作时长和工作压力，倡导健康生活方式，并提高情绪调节能力。     

PAC理论在教学运用中的研究初探

PAC理论作为人际关系心理学中的重要理论,它的＂心态转化原理＂能帮助学生克服人际沟通障碍,＂人际互动类型原理＂能够帮助学生选择解决问题的正确途径,＂P≡P-C≡C交往心态原理＂能使学生有效中断不良交往方式。总体上说,这一理论可以有效促进学生把握心理状态,深入理解问题,从而有助于提升教学效果。     

高校招投标采购的特点

随着高校向现代化教育技术的发展,购买仪器采购数量的增多,尤其是进口设备的采购,对现有的采购程序提出了新的挑战。文中从高校设备购置的特点出发,讨论了市场与竞争、如何选择采购方式、验收的重要意义以及在全过程的监督机制等问题。通过在实际中遇到的各种问题,提出了应该加强政府采购制度建设,改善市场竞争环境,强化设备采购前期调研工作,合理选择设备采购方式等。总结了高校仪器设备招标采购的经验,探讨了高校仪器设备招标采购的规律。     

CD44v6、E-cadherin和ki-67蛋白质与腮腺多形性腺瘤的生物学行为相关性研究

为检测腮腺多形性腺瘤中CD44v6、E-cadherin和ki-67蛋白表达,以探讨其与腮腺多形性腺瘤生物学行为的相关性。应用免疫组织化学SP法染色检测腮腺多形性腺瘤组、多形性腺瘤恶变组和瘤旁非瘤组织组各组间CD44v6、Ecadherin和ki-67蛋白表达。结果显示,(1)CD44v6、E-cadherin和ki-67在腮腺多形性腺瘤组中的阳性表达率分别为100%、96%和73.8%;(2)E-cadherin和ki-67在腮腺多形性腺瘤组、多形性腺瘤恶变组和瘤周非瘤组织间的阳性表达率均有差异,其表达与腮腺多形性腺瘤的浸润转移有关;(3)CD44v6在腮腺多形性腺瘤组与瘤周非瘤组织组,多形性腺瘤恶变组与瘤周非瘤组织组中的表达有统计学差异。由此可知,E-cadherin和ki-67与腮腺多形性腺瘤的生物学行为有关,可作为新的肿瘤标志物,其表达对判断预后有一定的价值。     

林木胸径与树高的关系研究

胸径与树高都是衡量林木生长好坏的两个非常重要的因子,为此借用黑龙江省红松的一组生长数据,对胸径与树高的非线性模型进行了拟合研究;经分析所选五个模型均相关性极显著,但以模型H=32.7008e-8.7297d相关性最好,F值为1110.000,高出其他F值2倍及以上.为此应用该模型大大的提高了树高因子的估测精度,并为今后的森林资源调查工作提供高精度的间接树高数据.