Macroscale environment

The macroscale environment is effected by every geometric variable and dimension and is a key parameter for successful scaleup of any process, whether microscale mixing is involved or not. This has some unfortunate consequences on scaleup since geometric similarity causes many other parameters to change in unusual ways, which may be either beneficial or... 

Academie researeh is also performed by multidiseiplinary groups of prineipal investigators, sometimes in eenters or other organizational environments Researeh and education also include the microscale (molecular level) and macroscale (systems level) ... 

Chemical engineers of the future will be integrating a wider range of scales than at r other branch of engineering. For example, some may work to relate the macroscale of the environment to the mesoscale of combustion systems and the microscale of molecular reactions and transport (see Chapter 7). Others may work to relate the macroscale performance of a composite aircraft to the mesoscale chemical reactor in which the wing was formed, the design of the reactor perhaps having been influenced by studies of the microscale dynamics of complex liquids (see Chapter 5). 

Figure 1. From the macroscale to the nanoscale a membrane electrode assembly has a polymer electrolyte membrane sandwiched between two catalyst layers and gas diffusion layers. The catalyst layer is composed of carbon particles impregnated with catalyst nanoparticles. Effective utilization of the catalyst particles depends on their local environment.

The reaction environment in a macroscale mbular reactor is nonuniform due to the distribution of residence times and diffusion-limited transfer of heat and mass in the radial direction. This section describes two approaches to improving reactor performance. 

Understanding how chemistry and the environment can influence macroscale observations. 

Note that supersaturations depend both on the macroscale cloud dynamics represented by the cloud updraft velocities (larger updrafts result in higher supersaturations) and on the microphysics (the details of the aerosol size distribution). Cleaner environments, with lower aerosol concentrations, usually result in higher supersaturations. 

The foremost reason why microfluidic systems provide attractive environments in which to perform synthetic chemistry lies in the dependency of fluid flow on scale. Put simply, fluid handling within microfluidic environments differs markedly from typical macroscale flow [2]. A variety of phenomena manifest themselves upon moving from the macroscale to the microscale, which in turn have a profound effect on both the efficiency and manner in which chemical reactions proceed. 

In the system we propose for coronary vessel delivery, the macroscale vector is represented by the PF 127/alginate gel, while the nano-/microscale vector is composed by NABD complexed with different molecules including cationic liposomes. In our case, the idea is to have a matrix where diffusion of nano-/microscale vectors toward the diseased tissue (inner artery wall) is driven mainly by the different concentration of the drug in the matrix and in the outside environment (matrix topology). 

Understanding the effects of membrane structure, water content and water distribution on proton conductivity has to invoke additional theoretical tools. They have to bridge many length scales from molecular environments to random heterogeneous structure at macroscale. This involves phenomenological concepts and homogenization methods in order to average over microscopic details [65]. 

The second main quantity used to characterize sound on a macroscale is the amplitude of the pressure fluctuations expressed as the sound pressure level (SPL) on the decibel (dB) scale with 20 Pa as reference level. Because the sound pressure depends on the distance from the source generating given sound power (energy per unit time) and on the acoustic environment (sound... 

Energy is available in a wide range of forms from our environment, as outlined in Table 1. Conventional energy conversion approaches are well developed at the macroscale to provide electricity, propulsion, heating, or cooling from these sources. A power source can be defined as the combination of an energy source with an... 

A slight variation is the real-time analyzer that is used to detect emissions from a process. This is an important class of process analytics but it will not be covered in this section since it is not directly interfaced to the chemical reactor and does not really change with microtechnology systems. However, the use of emissions monitoring can be every bit as important in the protection of plant personnel and the environment with microtechnology systems as with macroscale plants. 

This article highlights the most commonly used methods to perform cell sorting in microfluidic devices. Some of the microfluidic techniques presented here are a miniaturized version of conventional laboratory analysis techniques and devices, and take advantage of the reduced sample volumes and increased speed of analysis. Many other types of devices have successfully exploited the novel effects that arise in a microfabricated environment that are not evident on the macroscale. 

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