Influence of the span 80/Gelatin B combination on the formulation and stabilization of Argan oil-in-water emulsions

The present study aims to evaluate the effect of the combination of a linear protein: Gelatin type B and an oil-soluble emulsifier Span 80 (sorbitan monooleate) in the stabilization of argan oil-in-water emulsions. For this purpose, the emulsifiying properties of Gelatin itself with Argan oil as lipid phase were investigated first, by preparing oil-in-water (O/W) emulsions containing 10 wt%. Argan oil and varying Gelatin concentrations (0.5-2 % w/w), we have also formulated Argan O/W emulsions by span 80 alone at levels ranging from 1 to 6 wt%. Subsequentely, we explored the influence of the simultaneous application of the Span 80 and the gelatine on the stability properties and on the droplets size of Argan O/W emulsions, using different mixtures of the two emulsifiers. We compared the stability properties (flocculation, creaming, and phase separation) of argan O/W emulsions prepared with type B gelatine as the only emulsifier with those of emulsions prepared with span 80 and mixture of gelatin/Span. For stable emulsions, our analysis was completed with measurement of droplets size and Zeta Potential. Finally, all of the experimental results and the storage time showed that the emulsions prepared by 10 wt% argan oil and 2 (w/w) % Gelatin+ 3 wt% Span 80 were the most stable with optimum conditions for minimal creaming, small droplets size (size <1µm) and high net droplet charge (absolute value of ZP > 23). The presence of span 80 in coexistence with gelatin, even in small quantitiees, has a profound influence on the stability of the argan O/W emulsions.

Ionisation effects on precipitation

&lt;p&gt;Cloud processes leading to rainfall generation are suspected to be influenced by droplet charge. Droplet charging is abundant, and even in layer clouds, charging of droplets readily occurs at the horizontal cloud-air boundary. Droplet charging in such circumstances is proportional to the vertical current driven through the cloud by the global electric circuit. Small global circuit variations from natural influences, such as solar modulation of cosmic rays can be used to investigate this, but an alternative is presented by artificial introduction of ionisation. The atmospheric nuclear weapons test period, which reached its peak 1962-1964, caused exceptional anthropogenic disturbance to the global circuit, through the increased ionisation from steady sedimentation of stratospheric radioactive debris.&lt;/p&gt;&lt;p&gt;Measurements of the vertical current J&lt;sub&gt;z&lt;/sub&gt; made at Kew Observatory near London (51&amp;#176;28&amp;#8242;N, 0&amp;#176;19&amp;#8242;W) were several times greater than normal during 1962-1964, as a result of the widespread extra ionisation in the lower atmosphere. At Lerwick, Shetland (60&amp;#176;09&amp;#8242;N, 1&amp;#176;08&amp;#8242;W) where deposition of radioactive material occurred, the atmospheric electrical parameters were strongly affected by the enhanced ionisation. To investigate tropospheric ionisation effects on local cloud processes, rainfall days at Lerwick in 1962-64 have been analysed by considering reduced and enhanced ionisation periods. During the enhanced ionisation, the Lerwick rainfall distribution shifted towards heavier rainfall and is significantly different from the rainfall distribution for reduced ionisation days; the Lerwick cloud was also significantly optically thicker during the enhanced ionisation. This contrasts with other years of the Kew record, when J&lt;sub&gt;z&lt;/sub&gt; was relatively undisturbed. Whilst the ionisation conditions of 1962-64 were exceptional, controlled methods of enhancing tropospheric ionisation by non-radioactive means - such as corona emission - may nevertheless be promising for local rainfall modification, or even geoengineering of cloud properties.&lt;/p&gt;

A Review of the Effects of Droplet Size and Flow Rate on the Chargeability of Spray Droplets in Electrostatic Agricultural Sprays

The chargeability of liquid sprays is an important factor in determining the deposition efficiency of electrostatic pesticide sprays. The Rayleigh limit provides information on the maximum amount of charge a spray droplet can carry as a function of droplet size and liquid properties. This article reviews the literature to determine what fraction of the Rayleigh limit is achievable. Typically, less than 10% of the Rayleigh limit charge is obtained. The droplet charge per unit mass decreases with increasing droplet size and liquid flow rate. A correlation equation is derived from published data to predict spray droplet charge per unit mass from droplet size, flow rate, and charging voltage. Keywords: Droplet size, Electrostatic charging, Spray drift, Sprayers, Ultra-low volume spraying.