A new electrodynamic balance (EDB) design for low-temperature studies: application to immersion freezing of pollen extract bioaerosols
A new electrodynamic balance (EDB) design for low-temperature studies: application to immersion freezing of pollen extract bioaerosols
复制标题
DOI：
10.5194/amt-8-1183-2015
复制
发表时间：
2015-03
影响因子：
3.8
通讯作者：
H. Tong;B. Ouyang;N. Nikolovski;D. Lienhard;F. Pope;M. Kalberer
中科院分区：
文献类型：
--
作者：
H. Tong;B. Ouyang;N. Nikolovski;D. Lienhard;F. Pope;M. Kalberer
抽象的。本文介绍了一种新设计的冷态电动天平（CEDB）系统，用于研究过冷水滴的蒸发动力学和冻结特性。悬浮水滴所在位置的CEDB室的温度可以控制在−40至p40 °C的范围内，这是通过使用液氮冷却和正温度系数加热器加热的组合来实现的。液滴半径的测量是通过分析532 nm激光的Mie弹性光散射获得的。米氏散射信号也被用来识别和区分液滴冻结事件;液滴产生规则的条纹图案，而来自冻结颗粒的图案是不规则的。单悬浮水滴的蒸发速率计算从蒸发液滴的半径的时间分辨测量和一个明确的趋势的蒸发速率对温度的测量。在-4.5至-40 °C的温度范围内，获得了含水花粉提取物（花粉洗涤水）的统计冻结概率。研究发现，在-22.45（±0.65）°C的温度下，水桦（Betula fontinalis occurentalis）花粉的花粉洗涤水可以在浸没冷冻模式中充当冰核。此外，发现洗涤水的富含蛋白质的组分比非蛋白质组分具有显著更高的冰活性。
Abstract. In this paper we describe a newly designed cold electrodynamic balance(CEDB) system, built to study the evaporation kinetics and freezing properties of supercooled water droplets. The temperature of the CEDB chamber at the location of the levitated water droplet can be controlled in the range −40 to p40 °C, which is achieved using a combination of liquid nitrogen cooling and heating by positive temperature coefficient heaters. The measurement of liquid droplet radius is obtained by analysing the Mie elastic light scattering from a 532 nm laser. The Mie scattering signal was also used to characterise and distinguish droplet freezing events; liquid droplets produce a regular fringe pattern, whilst the pattern from frozen particles is irregular. The evaporation rate of singly levitated water droplets was calculated from time-resolved measurements of the radii of evaporating droplets and a clear trend of the evaporation rate on temperature was measured. The statistical freezing probabilities of aqueous pollen extracts (pollen washing water) are obtained in the temperature range −4.5 to −40 °C. It was found that that pollen washing water from water birch (Betula fontinalis occidentalis) pollen can act as ice nuclei in the immersion freezing mode at temperatures as warm as −22.45 (±0.65) °C. Furthermore it was found that the protein-rich component of the washing water was significantly more ice-active than the non-proteinaceous component.