Controlled droplet application

Significant advances have been achieved in both ULV and controlled droplet application (CDA) systems and further development of the charged panicle... 

There are interesting similarities between the promotion of biopesticides and Controlled Droplet Application (CDA) techniques (see below). As biological control agents, microbes (unlike insects) usually cannot be seen with the naked eye, and they are slow acting therefore explaining their modes of action can be difficult. ULV application, using very fine droplets, can similarly be an act of faith , with farmers who are unable to see spray clouds or deposits. Both... 

Clayton, J.S. (1992) New developments in Controlled Droplet Application (CDA) techniques for small farmers in developing countries - opportunities for formulation and packaging. Proceedings Brighton Crop Protection Conference - Pests and Diseases, 1, 333-340. 

In the commercial application, the drop tube method, as mentioned above, is suitable for mass production. The detailed investigations, such as temperature measurement of each small droplet and in situ observation of microstructure formation are not easy to attain because each droplet is in free fall. Here, the levitation method, where an Si droplet with a diameter of mm can be levitated by electromagnetic force using an electro-magnetic levitator (EML), as shown in Fig. 8.5, is a powerful investigation technique because the controlled droplet position enables us to measure the surface temperature of the droplet by pyrometer and to observe the crystallization behavior in situ by a high-speed video camera (HSV) [16-18]. 

Shui L, Eijkel J, van den Berg A (2007) Multiphase flow in microfluidic systems-control and applications of droplets and interfaces. Adv Colloid Interface Sci 133(1) 35 9... 

Figure 2 indicates the different types of emulsions. Simple emulsions are labeled as oil-in-water (0/W) when they exhibit oil drops dispersed in an aqueous phase, or water-in-oil (W/O) if the opposite occurs, while multiple or double emulsions are symbolized either by W,/0/Wi or Oi/W/O . Wi (respectively 0 ) and W2 (respectively O2) indicate the most internal phase and the most external one. Note that phases with subscript I and 2 may be identical or different. If they are not the same a likely difference in chemical potential may drive a mass transfer process, a phenomenon that is advantageously harnessed for controlled-release applications. Bieniulsions are emulsions containing two different internal phase droplets, either of the same nature (but different size) or of different nature (whatever the size). The first kind of biemulsion is used to control some property, as, for example, emulsion viscosity, whereas the second may be used to produce controlled chemical reaction or mass transfer between the two internal phases. 

An understanding of multiphase microflows is critical for the development and application of microstructured chemical systems in the chemical industry. As one of the most important meso-scientific issues, interfacial science could be a bridge connecting microscopic molecular components and macroscopic fluid behaviors in these systems. Working together with viscous and inertial forces, the interfacial force also dominates complicated multiphase flow patterns and well-controlled droplets and bubbles. In this review, the generation mechanisms of different flow patterns and the break-up rules for droplets and bubbles in microchannels are introduced first. The effects of the adjustable fluid/solid interfaces, or so-called wetting properties, of microchannels on multiphase flow patterns, as well as microchannel surface modification methods, are then discussed. The dynamic fluid/fluid interfaces in multiphase microflows with variable... 

The use of ttaditional disperse systems, e.g., macroemulsions, in the pharmaceutical industry has been limited due to manufacturing complexity and stability problems [117]. The characteristic properties of nano-emulsions (kinetic stability, small and controlled droplet size, etc.) make them interesting systems for pharmaceutical applications. Indeed, nano-emulsions are used as drug delivery systems for administration through various systemic routes. There are numerous publications on nano-emulsions as drug delivery systems for parenteral [17,18,28,29,118-124], oral [25,125-129], and topical administration, which includes the administration of formulations to the external surfaces of the body skin [32,130,131] and to the body cavities nasal [30,132] as weU as ocular administration [31,133-136]. Moreover, many patents concerning pharmaceutical applications of nano-emulsions have been registered [17,18,25,137-145]. An application of nano-emulsions in this field has been in the development of vaccines [33,146-147]. 

Various novel applications in biotechnology, biomedical engineering, information industry, and microelectronics involve the use of polymeric microspheres with controlled size and surface properties [1-31. Traditionally, the polymer microspheres larger than 100 /urn with a certain size distribution have been produced by the suspension polymerization process, where the monomer droplets are broken into micron-size in the existence of a stabilizer and are subsequently polymerized within a continuous medium by using an oil-soluble initiator. Suspension polymerization is usually preferred for the production of polymeric particles in the size range of 50-1000 /Ltm. But, there is a wide size distribution in the product due to the inherent size distribution of the mechanical homogenization and due to the coalescence problem. The size distribution is measured with the standard deviation or the coefficient of variation (CV) and the suspension polymerization provides polymeric microspheres with CVs varying from 15-30%. 

In principle, cathodic protection can be used for a variety of applications where a metal is immersed in an aqueous solution of an electrolyte, which can range from relatively pure water to soils and to dilute solutions of acids. Whether the method is applicable will depend on many factors and, in particular, economics — protection of steel immersed in a highly acid solution is theoretically feasible but too costly to be practicable. It should be emphasised that as the method is electrochemical both the structure to be protected and the anode used for protection must be in both metallic and electrolytic contact. Cathodic protection cannot therefore be applied for controlling atmospheric corrosion, since it is not feasible to immerse an anode in a thin condensed film of moisture or in droplets of rain water. 

Controlling Surface Wetting by Electrochemical Reactions of Monolayers and Applications for Droplet Manipulation... 

The present authors have had experience using rotary samplers for field studies involving relatively small droplets for vector control applications and for the measurement of droplet size at far-field distances. When using magnesium oxide slides, the spread factor for droplets varies from 0.75 for crater diameters up to 15 jam, to 0.8 for 15-20 p.m and 0.86 for crater diameters above 20 am. 

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