Temporal gradients in microfluidic systems to probe cellular dynamics: A review

Microfluidic devices have found a unique place in cellular studies due to the ease of fabrication, their ability to provide long-term culture, or the seamless integration of downstream measurements into the devices. The accurate and precise control of fluid flows also allows unique stimulant profiles to be applied to cells that have been difficult to perform with conventional devices. In this review, we describe and provide examples of microfluidic systems that have been used to generate temporal gradients of stimulants, such as waveforms or pulses, and how these profiles have been used to produce biological insights into mammalian cells that are not typically revealed under static concentration gradients. We also discuss the inherent analytical challenges associated with producing and maintaining temporal gradients in these devices.     

Fullerenes as mass sensors: A numerical investigation

This paper investigates the novel development of a mass sensitive nanosensor based on the use of individual spherical fullerenes. The main advantage of the mass sensing ability of spherical fullerenes in comparison with other nanomaterials such as carbon nanotubes (CNTs) or graphene nanoribbons (GNRs) is the fact that they present almost perfect geometric symmetry and thus a unique vibrational behavior which is independent from the location of the externally added nanoparticle. The study is conducted by the use of a computationally effective numerical scheme based on the adoption of appropriate three dimensional line spring elements as well as point mass elements to simulate the atomistic structure of fullerenes and interatomic interactions appearing between carbon atoms. The free vibration of C₂₀, C₆₀, C₈₀ and C₁₈₀ molecules is analyzed without and with an external nanoparticle of specific mass attached on their structure to calculate the arisen change in their natural frequencies and corresponding shape modes. A parametric study concerning the magnitude and location of the added mass is performed in order to evaluate the mass sensing ability of the fullerenes under consideration.     

Off-resonance frequency filtered magnetic resonance imaging

One of the main problems with rapid magnetic resonance imaging (MRI) techniques is the artifacts that result from off-resonance effects. The proposed off-resonance frequency filtered MRI (OFF-MRI) method focuses on the elimination of off-resonance components from the image of the observed object. To maintain imaging speed and simultaneously achieve good frequency selectivity, MRI is divided into two steps: signal acquisition and post-processing.     

MIL-101/P25复合材料的制备及光催化性能

本文采用水热法,将MIL-101负载到预处理过的P25表面,制得MIL-101/P25复合光催化材料,通过X射线衍射（XRD）、傅里叶变换红外（FTIR）、低温N₂物理吸附-脱附（BET）、热重（TG）、场发射透射电镜（FETEM）和光致发光光谱（PL）等对催化剂进行结构表征,同时考察MIL-101及复合材料的稳定性,并且提出协同因子指标来定量评价复合带来的协同效应。结果表明MIL-101呈片状,与P₂₅部分结合。复合后,MIL-101的稳定性得到提高。在适当的配比下,复合具有协同效应,当Cr（NO₃）₃·9H₂O与P25的物质的量之比为1：1时,复合材料对罗丹明B的可见光催化活性最高,协同因子达到1.64。复合材料对无色有机污染物水杨酸同样表现出良好的光催化效果。     

深水多波束测深系统脉冲压缩实时算法

线性调频信号是大时宽带宽积信号,通过脉冲压缩可提高探测距离和分辨率,已在深水多波束测深系统中得到广泛应用。针对深水多波束测深系统中脉冲压缩运算量大的问题,提出了一种基于分组的脉冲压缩实时算法。该算法对需要进行脉冲压缩的波束进行分组,每个节拍只计算一组波束,可大幅减少深水多波束测深系统脉冲压缩的运算时间,节省了处理器资源。该算法已成功应用于某深水多波束测深系统,经多次海试证明,工作稳定可靠。     

热力学数据对1, 3-丁二烯燃烧特性的影响

基于G4方法, 计算了1,^{3-丁二烯框架燃烧反应机理中102个物种的热力学数据, 并考察了振动非谐性、 频率校正因子以及受阻内转动对结果的影响. 结果表明, 考虑振动非谐性或采用不同的频率校正因子, 对热力学数据的影响不大; 考虑内转动后, 对热力学数据有较大影响. 而且考虑内转动后, 得到的热力学数据与实验热力学数据吻合得更好. 用所得热力学数据模拟了1,3-丁二烯的绝热燃烧温度以及点火延迟时间, 结果显示, 要得到可靠的绝热火焰温度, 对小分子(如CO和CO₂等)的热力学数据需要采用实验结果. 将用所得热力学数据模拟得到的点火延迟时间, 与机理本身的热力学数据所得点火延迟时间进行对比, 二者差别显著, 表明所得热力学数据主要通过改变一些反应的逆反应速率常数来影响点火延迟时间. 进一步确定了用所得热力学数据对点火延迟时间有显著影响的一些物种.}     

Tailoring the dielectric properties and energy storage density of 1−x(0.94NaNbO3−0.06SZ)−xBi2O3 through substitution strategy

Energy storage using dielectric capacitors is a growing area of research and development. However, designing a highly performing dielectric capacitor is still a challenge. Despite the excellent results achieved in lead-based dielectrics, lead-free substitutes are essential because of the environmental concerns associated with lead-based products. The lead-free 1?x (0.94NaNbO₃? 0.06SrZrO₃)+ x Bi₂O₃ ceramics abbreviated NNSZ + xB for x = 0.0, 0.05, 0.1, 0.15, and 0.20 was fabricated via solid-state reaction. A recoverable energy density of 2.93 J cm?³ was obtained for NNSZ+0.1B, associated with high thermal stability (25–130 °C), excellent cycling (N = 10⁵), and high efficiency (η) of 83.5%. Moreover, the introduction of Bi₂O₃ significantly improved the electrical insulation (?_r at 1 kHz = 1608 and tan δ = 0.0038) and breakdown strength (380 kVcm?¹) of NNSZ+0.1B by minimizing the formation of sodium, bismuth, and oxygen vacancies. The results obtained in this study provide a benchmark for further investigations on NaNbO₃-based ceramics. More importantly, this study suggests that NNSZ + xB ceramics can be used in pulsed power technology.     

太阳运动模拟平台的单片机控制

针对用太阳运动模拟平台实现太阳运行位置的全面预测和重现这一问题,提出了采用单片机对该平台进行控制,电机通过变频实现不同时间段不同速率运动模拟太阳运行轨迹的方法。根据输入日期计算出太阳的高度角和方位角,并转换为驱动电机的脉冲数和频率,电机带动执行机构运动使模拟光源到达预定位置。用编码器测量电机实际脉冲,定期进行误差校正来提高系统的稳定性和精度,减少误差。经过实验验证,该平台能够使模拟光源按照预计的轨迹运动,得出该方法是可行的,所设计的程序具有可靠性的结论。     

Adaptive RAKE receiver in chaos based pilot-added DS-CDMA system

This paper presents the theoretical analysis of adaptive multiuser RAKE receiver scheme in frequency selective fading channel for direct-sequence code division multiple access (DS-CDMA) system. Least mean square (LMS) algorithm is used to estimate the channel coefficients. Chaotic sequences are used as spreading sequence and corresponding bit error rate (BER) in closed form is derived for imperfect channel estimation conditions. Performances of chaotic sequences are compared with pseudorandom noise (PN) sequences. Under perfect synchronization assumption, various simulation results are shown to investigate the performance of the proposed system.