Electrostatic Evaluation of a Unipolar Diffusion and Field Charger of Aerosol Particles by a Corona Discharge

This article presents a unipolar diffusion and field charger by corona discharge is presented and electrostatically evaluated for charging aerosol particles. The electrostatic characteristics of the charger were investigated with an electrometer by measuring the ion number concentrations corresponding to the discharge and charging currents. The discharge and charging currents, and ion number concentration in the discharge and charging zones of the charger, increased with corona voltage. The magnitudes of the ion number concentration for positive and negative coronas in the discharge zone ranged from 1.34 × 10¹³ to 1.84 × 10¹⁵ ions/m³ and 7.34 × 10¹³ to 2.64 × 10¹⁵ ions/m³, respectively. For the charging zone, the ion number concentrations for positive and negative coronas ranged from 2.95 × 10¹³ to 1.52 × 10¹⁴ ions/m³ and 2.06 × 10¹³ to 1.47 × 10¹⁴ ions/m³, respectively. To predict the behavior of the electric field strength and lines in the discharge and charging zones of the charger, the electric field strength and distribution of the charger in the discharge and charging zones were calculated by a commercial computational fluid dynamics software package. Numerical calculation results of electric field distribution and lines through the inner electrode showed good agreement with experimental results. Also, the mean charge per particle for particle diameters were in the range of 0.01 to 50 µm for various operating conditions of the charger was theoretically evaluated. For both diffusion and field charging, lower aerosol flow rate and higher corona voltage resulted in an increase in the mean charge per particle within the charger. This simple charger proved to be particularly useful in diffusion and field charging of aerosol particles in particulate matter detector instruments for measuring PM10 and PM2.5 concentration.     

CHITOSAN-BASED FUEL CELL MEMBRANES

Chitosan complex membranes are prepared and characterized at room temperature. They are expected to be used as proton exchange membranes. The studied membranes are cross-linked membranes with sulfuric acid; salt-complexed membranes with lithium nitrate; cross-linked and salt-complexed membranes; plasticized and salt-complexed membranes; cross-linked, plasticized, and salt-complexed membranes; and doped membranes with sulfuric acid. A fixed amount of ethylene carbonate is used as plasticizer. It is found that the ion exchange capacity and hydrogen gas permeability of all membranes is better than that of Nafion membranes. However, their proton conductivities are worse than Nafion membranes. It can be stated that ethylene carbonate does not improve conductivity. An optimum amount of lithium nitrate salt can enhance conductivity. The formation of a sulfate group in cross-linked membranes is necessary for proton conduction. The proton conductivities of 4%cross-linked and 50%LiNO₃ membrane before and after acid doping are (3.11±0.40) × 10^?2 and (6.64±0.11) × 10^?2 S cm^?1, respectively. That of Nafion is (8.02±1.19) × 10^?2 S cm^?1.     

Influence of Pulsed Laser Deposition Modes on Properties of Nanocrystalline LiNbO3 Films

Russian Microelectronics - The influence of the duration of pulsed laser deposition on the properties of lithium niobate films is elucidated. An increase in the deposition time from 90 to 360 min...     

用NMR研究洋葱碳吸附水后的抗磁性

对洋葱状碳缺陷位吸附水分子的1H化学位移进行测试，并比较块状水和石墨烯、氧化石墨烯和纳米金刚石吸附水的化学位移。纳米金刚石和氧化石墨烯绝缘体的1H共振位置与块状水接近，然而石墨烯和洋葱碳吸附水呈现明显的化学位偏移，这是由导电的石墨烯片层抗磁屏蔽效应所致。质子的化学位移和抗磁性之间存在显著的相关性。     

Optimization of Ceramic Fillers for 0–3 Piezoelectric Composites

The effect of the preparation procedure on the structural perfection, morphology, and particle size of anisotropic ferroelectric powders intended for use as the active component of 0–3 piezoceramic–polymer composites is studied using x-ray diffraction and optical microscopy.     

Development of a PM2.5 sampler with inertial impaction for sampling airborne particulate matter

A simple and low cost PM_2.5 impactor for sampling airborne particulate matter was developed, designed and evaluated. The design was an assembly of an acceleration nozzle and an impaction plate. Particles with sufficient inertia were unable to follow air streamlines and impacted on the plate. Smaller particles followed the streamlines, avoided being captured by the plate and could then be collected on a downstream filter. Analytical and numerical models were formulated to predict collection efficiency, flow fields and vectors, and particle trajectories in the impactor. The modeling suggested that an optimal operational domain exists for the PM_2.5 impactor. A prototype was then built and tested. The collected particles on the impaction plate and downstream of the PM_2.5 impactor were analyzed by using scanning electron microscopy. Experimental results agreed well with the theoretical predictions. Testing of the PM_2.5 impactor prototype showed promising results for this airborne particulate matter sampler.