基于上转换纳米粒子的低损伤神经界面技术

Optogenetics is a neuromodulation technology that combines light control technology with genetic technology, thus allowing the selective activation and inhibition of the electrical activity in specific types of neurons with millisecond time resolution. Over the past several years, optogenetics has become a powerful tool for understanding the organization and functions of neural circuits, and it holds great promise to treat neurological disorders. To date, the excitation wavelengths of commonly employed opsins in optogenetics are located in the visible spectrum. This poses a serious limitation for neural activity regulation because the intense absorption and scattering of visible light by tissues lead to the loss of excitation light energy and also cause tissue heating. To regulate the activity of neurons in deep brain regions, it is necessary to implant optical fibers or optoelectronic devices into target brain areas, which however can induce severe tissue damage. Non- or minimally-invasive remote control technologies that can manipulate neural activity have been highly desirable in neuroscience research. Upconversion nanoparticles (UCNPs) can emit light with a short wavelength and high frequency upon excitation by light with a long wavelength and low frequency. Therefore, UCNPs can convert low-frequency near-infrared (NIR) light into high-frequency visible light for the activation of light-sensitive proteins, thus indirectly realizing the NIR optogenetic system. Because NIR light has a large tissue penetration depth, UCNP-mediated optogenetics has attracted significant interest for deep-tissue neuromodulation. However, in UCNP-mediated in vivo optogenetic experiments, as the up-conversion efficiency of UCNPs is low, it is generally necessary to apply high-power NIR light to obtain up-converted fluorescence with energy high enough to activate a photosensitive protein. High-power NIR light can cause thermal damage to tissues, which seriously restricts the applications of UCNPs in optogenetic technology. Therefore, the exploration of strategies to increase the up-conversion efficiency, fluorescence intensity, and biocompatibility of UCNPs is of great significance to their wide applications in optogenetic systems. This review summarizes recent developments and challenges in UCNP-mediated optogenetics for deep-brain neuromodulation. We firstly discuss the correspondence between the parameters of UCNPs and employed opsins in optogenetic experiments, which mainly include excitation wavelengths, emission wavelengths, and luminescent lifetimes. Thereafter, we introduce the methods to enhance the conversion efficiency of UCNPs, including optimizing the structure of UCNPs and modifying the organic dyes in UCNPs. In addition, we also discuss the future opportunities in combining UCNP-mediated optogenetics with flexible microelectrode technology for the long-term detection and regulation of neural activity in the case of minimal injury.     

计算机分子模拟在分子印迹技术中的应用

传统的分子印迹技术对模板分子、功能单体、交联剂、致孔剂等的筛选往往依靠经验,常通过反复实验对合成条件进行优化,存在实验周期长、耗材量大等问题。计算机分子模拟技术的应用在实验过程中起到可预见性指导作用,可以实现精准识别位点的裁制、识别驱动力的设计,通过结合能等物化特征参数计算优化识别体系的稳定性,从而合理选择模板分子、功能单体、交联剂、致孔剂,优化聚合条件,以提高聚合物识别特异性和亲和力,缩短实验周期,更符合绿色化学的理念。本文简单介绍了计算机分子模拟技术,重点对其在分子印迹技术中的指导作用进行了综述,并对其在分子印迹技术中的应用进行了展望。     

现代数字物理教学连载④——工科基础量子教学中如何发挥数字化技术的作用

介绍了如何运用数字技术的三维表现手法和能力以及数值计算与模拟功能来深化量子理论的基本概念与基础内容的教学,充实了量子理论实际应用的教学内容.     

现代数字物理教学连载⑩——在数字技术平台上的研究式学习

介绍了大学物理教学中,如何利用数字技术平台引导学生进行自主的研究式学习.首先是知识的拓展与转移,接着是教师指导下的研究与探索,最后是学生自主独立的研究与创新.实践证明,我们创造的这一教学方法对于培养学生的科学素质与能力十分奏效.     

Diffusion of Acetic Acid Across Oil/Water Interface in Emulsification-Internal Gelation Process for Preparation of Alginate Gel Beads

Alginate has been widely used in cell microencapsulation and drug delivery systems in the form of gel beads or microcapsules.Although an alternative novel emulsification-internal gelation technology has been established and both the properties and the potential applications of the beads in drug delivery systems have been studied,the mechanism has not been well understood compared with the traditional droplet method(external gelation technology).On the basis of our previous knowledge that the novel technology is composed of complicatedly consecutive processes with multistep diffusion and reaction,and the diffusion of acetic acid across oil/water interface being the prerequisite that determines the occurrence and rate for the reactions and the structures and properties of final produced gel beads,a special emphasis was placed on the diffusion process.With the aid of diffusion modeling and simple experimental design,the diffusion rate constant and diffusion coefficient of acetic acid across oil/water interface were determined to be in the orders of magnitude of 10-6 and 10-16,respectively.This knowledge will be of particular importance in understanding and interpreting the formation,structure of the gel beads and the relationship between the structure and properties and guiding the preparation and quality control of the gel beads.     

基于光谱技术的杨梅汁品种快速鉴别方法的研究

为了实现杨梅汁品种的快速无损鉴别,提出了一种用可见和近红外光谱技术快速鉴别杨梅汁品种的新方法。首先采用偏最小二乘法进行模式特征分析,经过交互验证法判别,确定最佳主成分数为9。完成特征提取后,将这9个主成分作为神经网络的输入变量,建立了三层BP神经网络,实现类别预测的同时也完成了数学建模与优化分析工作。3个品种的杨梅汁样本数均为20,共计60个样本。在神经网络学习中,将其分成训练集样本51个和预测集样本9个。对9个未知样本进行预测,准确率为100％。说明本文提出的基于光谱技术和模式识别的方法具有很好的分类和鉴别能力。     

激光对远距离运动目标的辐照性能研究

研究激光对远距离运动目标的辐照功率在激光通信、激光破坏等领域具有重要意义。一般估算辐照功率时常忽略目标的随机运动。在考虑目标的随机运动概率密度分布的基础上,建立了远距离运动目标的精确激光辐照功率模型,并与辐照静止目标时的情形进行了定量的分析比较。辐照运动目标等效于扩大的激光束辐照静止目标。当系统的瞄准方差小于由模型计算出的等效静止方差极限时,可将目标看作为静止状态,由此带来的辐照功率估算误差小于10%,否则在计算时必须考虑目标的运动状态。     

基于虚拟仪器的视频图像采集系统设计

应用虚拟仪器技术,在Lab VIEW7．1开发平台上设计了利用IMAQ Vision for LabVIEW基于NI IMAQ 1405图像采集卡的图像采集系统。该系统对CCD电视、红外热像仪等输出的模拟视频图像具有采集能力,且结构简单,扩展方便,效率高,通用性强,显示了虚拟仪器技术的在信息技术研发中的显著优势。     

分辨力增强技术的频谱分析

离轴照明和衰减型相移掩模作为重要的分辨力增强技术,不仅可以提高光刻的分辨力,同时还可以改善成像焦深,扩大光刻工艺窗口,实现65~32 nm分辨成像。从频谱的角度分析了离轴照明和衰减型相移掩模对成像系统交叉传递函数和像场空间频率分布的影响,研究这两种技术的物理光学本质,由此进一步优化光学成像系统设计、分辨力增强技术和确定设备使用的参量。对分辨力增强技术的频谱分析研究表明,分辨力增强技术通过调整像场频谱分布,改善了光学光刻的图形质量。对于65 nm密集图形,离轴照明和相移掩模结合后可以使成像衬比度最高达到0.948,工艺窗口在5%曝光范围内焦深达到0.51μm。     

光纤中高斯型伪随机序列码偏振度的理论分析和实验研究

推导了准单色光波情况下高斯脉冲伪随机序列偏振度的简洁数学表达式.理论分析结果表明,偏振度与差分群延迟之间的关系与线路啁啾和光纤色散无关,并且此关系可以由光信号频谱半宽度Δω和分光比γ唯一确定.用10 Gbit/s 7级m序列归零码进行的实验表明:实验结果与理论推导基本一致,从而验证了推导公式的正确性.