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4 Gaps and Challenges
Pages 41-47

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From page 41...
... In addition to the broad research themes described, two cross-cutting topics that are important in materials Advancing the Understanding of Complex Mixtures chemistry have particular resonance in chemical separations: establishing standards to enhance reproducibility Samples and process streams encountered in separa tion problems are almost always complex mixtures that 1Separation system refers to an entire process or procedure that have many chemical components. Idealized concepts of yields a separation; it can include the separation material, devices, pure feeds with clean carriers and single-product chemisand other components.
From page 42...
... nanopores, for example, the adsorbed concentration can When components of interest are present at low con- vary roughly exponentially with the molecular weight of centrations, as is the case in many analytical settings, un- the adsorbing species, making the presence of high-moderstanding and controlling the response of the separa- lecular-weight contaminants in input streams important. tion process to the full spectrum of analytes that might Critical scientific challenges exist in developing a confound it are critical.
From page 43...
... lenging. Achieving Separations with a Wide Dynamic Range Separating Trace Compounds and Using Multistep Processes Mixtures usually have multiple species at various concentrations.
From page 44...
... No matter what separation and analysis methods are used to achieve deep proteoform coverage for the analysis of highly modified proteins, such as histones, time-consum ing fractionation is undertaken and requires days to complete. Recently, comprehensive nanoflow two-dimensional liquid chromatography combined with high-resolution mass spectral detection provided top-down proteoform char acterization of HeLa core histones; this method identified nearly 400 proteoforms, twice the number of previously identified proteoforms, from a small sample quantity (1.5 µg)
From page 45...
... A central challenge is to SCIENTIFIC CHALLENGES IN understand the fundamental mechanisms that control the UNDERSTANDING TEMPORAL CHANGES evolution of nonequilibrium states, particularly in com THAT OCCUR IN SEPARATION SYSTEMS plex environments. Without such understanding, efforts to implement accelerated testing protocols that speed the To maximize their scientific or practical value, sepa- cycle of materials development or work to synthesize maration systems must be reliable when exposed to streams terials with intrinsically improved stability are likely to of broad and variable composition.
From page 46...
... In many chemical separations and to drive the development of ad- ways, chemical separations are ripe for advances based vanced techniques, community efforts to enhance the reli- on those methods inasmuch as the number of separation ability and reproducibility of data and to create well-de- materials and operating environments and the span of fined model systems that can be characterized by an array chemical challenges are far larger than can be systematiof orthogonal tools are needed. The associated challenges cally addressed through direct experiments.
From page 47...
... 2016. Hollow Fiber Carbon Molecular Sieve lenges associated with the evolution of separation sys- Membrane and Preparation and Use Thereof.


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