激光二极管触发光导开关实验研究

介绍了利用大功率半导体激光二极管触发3 mm间隙GaAs光导开关、产生非线性电脉冲输出的实验,激光二极管输出功率为70 W,上升前沿约20 ns,脉冲半高宽（FWHM）约40 ns。随着开关两端偏置场强增加,输出电压也线性增加,当偏置场强超过一定阈值,增至约2.53 kV/mm时,经过一个较小的电压峰值和时间延迟后,输出电压急剧增加,产生雪崩现象。实验结果表明:GaAs开关非线性输出的产生与载流子聚集和碰撞电离有关,偏置电场的提高增加了开关芯片中载流子聚集数量,加剧了碰撞离化程度,从而使开关从线性模式进入雪崩模式。     

滴水感应起电仪的实验及其改进研究

滴水自激感应起电仪,即开尔文滴水感应起电仪,是利用水滴流动与玻璃管摩擦起电,并静电感应循环累积电荷而产生越来越高的电位差的静电起电装置。本文通过对装置的系统划分,研究各部分对最终起电现象的影响,主要在漏电测试、电荷累积测量和仪器装置材料更换等方面来改进仪器装置。经过实验改进后,开尔文滴水感应起电仪的起电效果明显,现象稳定。     

Accumulation,Directional Delivery and Release of Nanoparticles along a Nanofiber

Controllably accumulating and delivering nanoparticles (NPs) into specific locations are a central theme of nano-engineering and important for targeted therapy or bacteria removal. Here we present a technique allowing bidirectional accumulation, directional delivery and release of nanoparticles through two 980-nm-wavelength counter-propagating evanescent waves in an optical nanofiber (NF). Using 713-nm-diameter polystyrene NPs suspension and an 890-nm-diameter NF as an example, we experimentally and theoretically demonstrate that the NPs delivered along the NF surface in opposite directions are accumulated into the region where the scattering loss of the NPs is maximum, and about 90% of the incident optical field from both ends of the NF can be coupled into the region. Moreover, the accumulation region can be controlled by altering the incident optical power ratio of the two counter-propagating laser beams, while the accumulated NPs can be delivered and then released into the specific locations by turning off the two lasers.     

Validation of a particle impact breakage model incorporating impact number effect

This paper presents validation of a particle impact breakage model i.e. Vogel and Peukert model with a focus on the impact number. The Vogel and Peukert model developed based on mechanical and statistical foundation has been widely used in various fields such as mineral engineering and chemical engineering but is barely studied in the application of repeated impact. The selective breakage data in the literature is collected to provide the database for model validation. It has shown that the Vogel and Peukert model is generally applicable to all the breakage cases considering the impact number. The effect of impact number is further elaborated in the population balance model (PBM) whereas the particle dynamics are provided from Discrete Element Method (DEM) simulation of an impact pin mill. The global system analysis of impact number is carried out with the synergic effect from impact velocity. The successful validation of Vogel and Peukert model incorporating the effect of impact number demonstrates its versatility whilst other key parameters such as impact energy and particle size can be considered in parallel.     

Adsorptive denitrogenation of indole from model fuel oil over Co-MAC: Adsorption mechanisms and competitive adsorption

The present research article depicts the adsorptive denitrogenation of indole-containing model oil using cobalt-incorporated acid-activated carbon (Co-MAC). The active metal incorporated acetic acid-activated bio-sorbent showed a significant adsorption capacity for indole from model fuel oil than mere activated carbon. In a batch study, maximum 96% indole removal was achieved with an initial indole concentration of 500 mg/L, catalyst dose of 10 g/L, time of 4 h, and reaction temperature of 303 K. The non-linear regression analysis was opted to fit the experimental equilibrium data into various adsorption isotherms, including Langmuir, Freundlich, Temkin and Redlich, and Peterson. Thermodynamic parameters of adsorption were investigated, and the entropy and heat of adsorption change were determined to be 0.26 kJ/mol K and 57.31 kJ/mol, respectively. Besides, a plausible adsorption mechanism of indole was also explored.     

Voltammetric Determination of Marbofloxacin at Carbon Paste Sensor Integrated with Copper Oxide Nanoparticles

The present work introduced copper oxide nanoparticles as an efficient electrode modifier for sensitive adsorptive differential pulse voltammetric assaying of marbofloxacin (MRB) in pharmaceutical formulations and surface water samples. In the presence of sodium dodecyl sulphate (SDS) at pH 4.0, the marbofloxacin molecule was irreversibly oxidized at the electrode surface showing an anodic oxidation peak at 0.954 V. The electrode reaction mechanism was assumed as adsorption-reaction controlled accompanied by the transferring of two electrons and proton exchange in agreement with the molecular orbital calculations performed on MRB molecule suggesting the oxidation of the amino group in the piperazinyl ring. At the optimized measuring conditions, the recorded peak heights were linearly correlated with the MRB concentration within the range from 6.67 to 360 ng mL⁻¹, and the estimated LOD value was 2.2 ng mL⁻¹. The integrated sensor showed a prolonged operational lifetime with good reproducibility of measurements. Based on the selectivity and sensitivity of the proposed method, MRB was successfully assayed in pharmaceutical formulations and surface water samples with mean average recoveries agreeable with the official method.     

Detachable Porous Organic Polymers Responsive to Light and Heat

Stimuli-responsive porous materials have captured much attention due to the on-demand tunable properties. Most reported stimuli-responsive porous materials are based on molecule isomerism or host-guest interaction, and it is highly desired to develop new types based on different responsive mechanism. Herein, inspired by natural cells which have the ability to fuse and divide induced by external stimulation, we report a new type of stimuli-responsive porous material based on detachment mechanism. A detachable porous organic polymer, namely DT-POP-1, is fabricated from the polymerization of anthracene-containing monomer (AnMon) when irradiated by 365 nm UV light. DT-POP-1 can detach into the monomer AnMon when irradiated with 275 nm UV light or heat. Such polymerization/detachment is reversible. The detachment results in a big difference in porosity and adsorption capacity, making the present detachable porous polymer highly promising in adsorptive separation and drug delivery.