盐在干燥胶体溶剂中结晶的聚集模式

Multi-scale Patterns formed by Sodium Sulphate in a Drying Droplet of Gelatin

We present a study of patterns, formed in drying drops of aqueous gelatin solution containing sodium sulphate. The patterns are highly complex, consisting of a hierarchical sequence of rings which form concentric bands as well as dendritic crystalline aggregates. When the preparation of the complex fluid is done by mixing an aqueous solution of the salt with an aqueous solution of gelatin prepared separately, another feature is observed in the pattern on the dried out drop. This is a viscous fingering pattern, superposed on the series of rings. We try to explain the origin of these two feature…

Lifetime of sessile saliva droplets in the context of SARS-CoV-2

Spreading of respiratory diseases, such as COVID-19, from contaminated surfaces is dependent on the drying time of the deposited droplets containing the virus. The evaporation rate depends on environmental conditions, such as ambient temperature and relative humidity and physical properties (e.g., droplet volume, contact angle and composition). The respiratory droplets contain salt (NaCl), protein (mucin), and surfactant (dipalmitoylphosphatidylcholine) in addition to water, which are expected to influence the evaporation in a big way. A diffusion-based theoretical model for estimating the dry…

干燥蛋白质溶液滴的裂纹模式

Crack patterns in drying protein solution drops

牛血清白蛋白盐溶液的沉积液滴在蒸发过程中经历凝胶化和破裂。由于蒸发引起的应力演化和松弛引起的应力演化之间的竞争，出现在胶凝液滴边缘的裂纹是规则间隔的。随后，平均裂纹间距以意想不到的方式演变，与沉积物厚度成反比而不是成正比。这种演变归因于平均收缩应力随时间的变化，裂纹图案是纯弹性的，而不是蒸发控制的。

胶体-胶体相互作用影响受限胶体干燥图案的网络形态

Colloid-Colloid Interactions Impact Network Morphology of Confined Colloidal Drying Patterns

该研究探究受限胶体干燥图案的网络形态，通过改变盐浓度调控胶体相互作用，发现其遵循默里定律，盐浓度会影响网络拓扑结构。

Insights on drying and precipitation dynamics of respiratory droplets in the perspective of Covid-19

We isolate a nano-colloidal droplet of surrogate mucosalivary fluid to gain fundamental insights into the infectivity of air borne nuclei during the Covid-19 pandemic. Evaporation experiments are performed with salt-water solutions seeded with a viral load of inactive nanoparticles in an acoustic levitator. We seek to emulate the drying, flow and precipitation dynamics of such air borne mucosalivary droplets. Observations with the surrogate fluid are validated by similar experiments with actual samples from a healthy subject. A unique feature emerges with regards to the final crystallite dimen…

Statistical Image Analysis of Drying Bovine Serum Albumin Droplets in Phosphate Buffered Saline

A bio-colloidal drying droplet can be used as a pre-diagnostic technique. However, a successful clinical setting requires a fundamental understanding of the final morphology and the way it is related to the initial state of the constituents present in the droplet. This chapter focuses on the physics associated with different pattern formations in the globular protein, bovine serum albumin (BSA) at different phosphate-buffered saline concentrations. The study reports that the first-order statistics (FOS) and the gray level co-occurrence matrix (GLCM) analysis are capable of capturing structural…

盐结晶对多孔介质的损伤

Damage in porous media due to salt crystallization

我们调查了砂岩中两种最常见的盐：氯化钠和硫酸盐的盐损害的起源。结果表明，所观察到的两种盐之间的损害的差异是直接相关的结晶动力学和盐溶液和晶体相对于石头的界面性质。我们表明，对于硫酸钠，水合和无水晶体的存在，特别是它们的溶解和结晶动力学是负责的损害。使用磁共振成像和光学显微镜，我们表明，当水吸收硫酸钠污染的砂岩，然后在室温下干燥，大的损害发生在孔隙中充满盐的区域。在部分溶解后，存在于这些区域中的无水硫酸钠盐引起硫酸盐的水合相以簇的形式非常快速地生长，所述簇形成在剩余的无水微晶上或附近。这些簇的快速生长产生超过石头的拉伸强度的应力，导致损坏。氯化钠只形成无水晶体，因此在实验中不会造成损害。