Bruce R. Locke - US grants

9311901 Locke This project is on research to develop a new material for use in electrophoresis and other bioseparation techniques. The new material consists of a polyacrylamide gel with controlled channels that are formed by inducing gelation around liquid crystalline DNA solutions. Once formed, the gels will be characterized experimentally by measuring rates of diffusion and electrophoretic migration. Also, modeling and computer simulation of the transport processes will be performed. ***

9521381 Locke This project is on research to develop and characterize new, nano-structured porous media for improved separations of biological macromolecules by electrophoresis or chromatography. Hydrogels with tailored internal channels or pores having defined diameters in the range from approximately 2 to several nanometers will be created by using semi-rigid rod-like polyions or amphiphiles (surfactants) that form lyotropic liquid crystalline phases to template the internal structure. Both isotropic and anisotropic channelized (hence nano-structured) media will be prepared. The specific aims of this research include: (1) synthesis of several classes of nano-structured hydrogels; (2) development and application of new methods for characterizing the internal pore structures of hydrogels; (3) measurement of size exclusion limits and transport properties (electrophoretic and diffusive) of molecules within structured and conventional hydrogels; and (4) modeling molecular transport in conventional and structured gels. ***

INT 0086351
Locke

This international cooperative research project involves three research groups, one in the Unites States, one in the Czech Republic and one in Croatia. Bruce Locke of Florida State University, Tallahassee, serves as the principal investigator along with partners Pavel Sunka from the Czech Institute of Plasma Physics, Prague, and Natalija Koprivanac of the University of Zagreb, Croatia. Their overall objective is the development and analysis of a type of advanced oxidation technology for the degradation of complex industrial and commercial organic dyes in aqueous solutions. Specifically their work features development and evaluation of liquid phase electrical discharge reactors for the chemical degradation of azo dyes, reactive dyes, and 3-phynylmethand type dyes.

The international project builds upon the strengths of each lab including Locke's expertise in analysis of chemical reactors including electrical discharge reactors, Koprivanac's expertise in chemical reactions involving synthesis and degradation of organic dyes, and Sunka's strengths in plasma physics and analysis of electrical discharge reactors for both gas and liquid applications. Findings are expected to lead to an improved understanding and eventual development of: 1) new electrode materials for liquid phase electrical discharge processes using plasma-spraying technology in Prague,
2) new reactor configurations combining gas and liquid phase discharges in Tallahasee, and, in Zagreb, 3) chemical reaction pathways for dye degradation using ozone and or hydrogen peroxide in combination with various zeolites. If successful, combined results should yield more efficient and effective processes for the degradation and removal of complex organic dyes from commercial, industrial and manufacturing wastewater.

This project in engineering processes fulfills the program objective of advancing scientific knowledge by enabling experts in the United States and Central Europe to combine complementary talents and share research resources in areas of strong mutual interest and competence.

Most cells are small, with dimensions <100mm along the shortest axis. Small size promotes a high surface area to volume ratio and short intracellular diffusion distances, both of which are thought to be necessary design features of cells. However, cells of some organisms are nearly 10-fold larger than the norm. In some crustaceans, muscle fibers from juvenile animals have "normal" dimensions (<100mm), but as the animals grow, some of these fibers may exceed 600mm. Attaining such a large size while maintaining function should be difficult or impossible, which raises the question: What are the rules and tradeoffs that govern cell size?
The effects of developmental increases in cell size will be examined in isolated fast-twitch muscle fibers of the blue crab, Callinectes sapidus. Size-associated changes in muscle structure, metabolism, and contraction will be examined using methods that include electron microscopy, chemical assays, nuclear magnetic resonance and polarographic measurements of oxygen consumption. In addition, a reaction-diffusion mathematical model will be generated to aid interpretation of experimental data. This study constitutes a novel view of cellular energetics that is broadly applicable. Once the rules are established for an extreme model system, the approach can be applied to traditional models. This will be particularly useful for studying the impact of energetic challenges like hypoxia, exercise regimes and developmental processes, all of which are inherently linked to cell size.
This is a collaboration of biologists and chemical engineers. The lead institution (UNCW) emphasizes undergraduate education, and undergraduate students will work alongside graduate students and the PIs. The research environment at the lead institution will be enhanced by the project's multi-disciplinary approach, and students will benefit from facilities and expertise at the collaborating institution. At the collaborating institution (FSU), the work will also involve training of undergraduate and graduate students. Mathematical modeling will form the basis for the dissertation of at least one graduate student, and undergraduate participation will be sought for all phases of the project.

The 4th International Symposium on Non-thermal Plasma Technologies for Pollution
Control and Sustainable Energy Development will be held in Panama City Beach, Florida, May 10-14, 2004. It is devoted to advancing the field of non-thermal plasma processes for environmental protection, including applications to air and water treatment and to sustainable energy processing. This meeting is intended to assemble experts from all over the world to present recent advances to the field and to discuss the prospects of these technologies for future development and study. The objectives of this meeting are therefore:
1) to assemble key research groups working on the environmental applications of non-thermal
plasma including air and water treatment and sustainable energy processing,
2) to provide a stimulating environment to foster scientific exchange and discussion of the most
important current issues related to the development of this area of technology, and
3) to conduct extensive discussions on the directions for future work and development.
This award provides supplemental funding to support this conference through some travel and publication costs. This conference can lead to broader impacts as follows. The conference will enhance and promote collaboration among scientists and engineers from large variety of disciplines and from a wide range of nations. It will engage a number of graduate students, and particularly women and under-represented minorities in order to develop the next generation of researchers. The intellectual merit of the conference is reflected in the high quality of the participating researchers representing major laboratories from top institutions worldwide. It will provide useful input to NSF as a guide to grant investments in this evolving field.

A non-thermal plasma is a plasma, or collection of free and randomly moving ions, that is
characterized by low background temperature, or energy, in combination with highly energetic
electrons. Typically, non-thermal plasma can be produced using a wide variety of high voltage
electrical discharges (e.g., AC, DC, and pulsed) as well as with electron beams. The largest
commercial application of non-thermal plasma in the environmental field is the use of AC
dielectric barrier discharge reactors for producing ozone, generally, subsequently used in water
treatment. Other commercial applications of non-thermal plasma include flue gas treatment from
power plants and incinerators and indoor air cleaning. Over the last 15 years there has been
considerable interest and research devoted to testing, evaluating, and developing non-thermal
plasmas for other applications. These other applications include treatment of volatile and
hazardous organic compounds in gases, treatment of nitrogen oxides and particulate matter from
the exhaust of mobile sources, treatment of organic, inorganic, and biological matter in
contaminated water, synthetic chemical processes, and destruction of hazardous chemical and
biological agents. While the technology for ozone generation is fairly mature, developments for
other applications are intensively under investigation due to the high sensitivity of reactor
performance on the reactor design and operating conditions (e.g., gas and/or liquid composition,
nature of applied electric field, addition of catalysts, and other factors). Recent developments in
the fields of plasma-catalysis, gas-liquid discharge phenomena, and hydrocarbon reforming from
natural gas are particularly promising and can contribute to the development of useful and efficient technologies.

Many types of muscle grow by increasing cell size, such that in juvenile animals the cells are small, but during development they may become quite large. This leads to changing constraints both on the transport of oxygen and nutrients from the blood to the cell and intracellular metabolite diffusion across the cell. Thus, during development muscle fibers must preserve function while navigating a multi-dimensional energetic landscape that encompasses molecular transport, ATP demand, behavior, body mass range and evolutionary history. This work will address the question: Are muscle cells as big as they can be without compromising function? The P.I.s will examine changes in muscle structure and function during growth in a diversity of fishes and crustaceans. The experimental objectives are: (1) to use light and electron microscopy to characterize cell architecture, (2) to apply magnetic resonance spectroscopy to in vivo and ex vivo muscle preparations to determine rates of ATP turnover, (3) to construct a reaction-diffusion mathematical model that integrates oxygen flux and intracellular metabolite diffusive flux, and (4) to use the model to define the limits of metabolic function for any combination of fiber size and ATP turnover. It is expected that muscle cells approach molecular transport limitation as the animals grow, but that all stages of development will be influenced by limits that are ultimately encountered only in the adults. This is a collaborative research project with a variety of broader impacts. A primary emphasis will be on the training of undergraduate and graduate students, including underrepresented groups. This training will be implicitly cross-disciplinary, and will involve both engineering and biology students. These students will be involved in experimental approaches that include the use of state-of-the-art magnetic resonance instruments at the National High Magnetic Field Laboratory, as well as rigorous mathematical modeling and computer programming.

CBET-0839984
Locke

A one-year exploratory research project builds on preliminary work studying electrical discharges in water. Such discharges are of fundamental and practical interest for various chemical, biomedical, and environmental applications. The key preliminary observation was that H2O2 is formed more slowly near the boiling point of low-conductivity water, where the discharge occurs in small water-vapor bubbles, and in higher-conductivity water, where the discharge appears to form and propagate on the inside of large water-vapor bubbles. H2O2 is used as an indirect indicator of the formation of the active OH radicals.

The central hypothesis of the present work is that the much smaller density of water molecules in the bubble phase than in the condensed liquid phase causes the reduced H2O2. In the research, H2, O2, H2O2, and OH formation will first be measured as functions of solution conductivity (up to 2000 ìS/cm), of temperature to 100 C, of the exposed area of the needle electrode, and of addition of various other gases (argon and oxygen) bubbled into the solution. The measurements of formation rates and stoichiometry will then used to test the mathematical model of electrical discharge channels in water previously reported by the group.

A basic understanding of electrical discharge in water near the boiling point should provide insight into the fundamental processes occurring in electrical discharge in water and in gas-liquid environments and can lead to insight into how to develop such discharges for practical use. Previous work has provided key information on the formation of electrical discharges in liquid water under ambient temperature and pressure conditions. However, while the effects of elevated pressure on liquid-phase water discharges have been reported, no previous work has been reported on electrical discharge in high-temperature water; that is, near boiling.

0932481
Locke

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

The interaction of liquid (e.g., water) with plasma (typically an ionized gas) occurs in a wide range of technological applications and natural phenomena including liquid-phase electrical discharge for arthroscopic surgery, lithotripsy for kidney stone treatment, wound healing and disinfection, synthesis of nanoparticles, plasma-assisted combustion, microsensors for chemical analysis, lightning discharges, corrosion in high-voltage electrical transmission and air flow control using plasma actuators. The relatively unexplored field of plasma-chemical reactions in gas-liquid plasma may also have a broad impact in industrially important applications where gas-liquid chemical reactions are important (e.g., air pollution study and control and the production of useful chemicals such as methanol or hydrogen and other fuels). This work will focus on studying a gas-phase electrical discharge with a spray of small micron-size water droplets into the plasma because this approach has been shown to be potentially very energy efficient for initiating a variety of chemical reactions, including the formation of hydrogen peroxide. Analysis of plasma interactions, particularly the chemical reactions initiated in such systems with small droplets of water, is vital to developing our understanding of plasma with condensed liquids in general.

This work will focus on two general cases of 1) reaction products, including hydrogen peroxide, oxygen, and hydrogen, from pure water with Ar and O2 carrier gases and 2) formation of methanol from methane and water droplets with Ar carrier. The first case is of fundamental importance for all hydroxyl radical reactions initiated in the plasma and the second, while of significant importance in the energy field for production of liquid fuels, provides an example of gas-liquid reactions with reasonably well characterized reaction pathways and mechanisms. The proposed work will use a range of experimental techniques including aerosol particle size measurements, flow visualization, emissions spectroscopy, and chemical analysis to develop our understanding of how reactive chemical species like hydroxyl radicals are formed by water droplets flowing into a plasma reactor. Mathematical modeling of the transport coupled to the plasma chemical reactions will be conducted. Fundamental analysis using molecular dynamics will also be conducted to study the basic interactions of electrons with condensed water surfaces and to assist in interpretation of the experimental studies.

This project is expected to lead to the development of fundamental knowledge on how plasma in gas-liquid environments leads to the formation of reactive species and how it affects some of the applications mentioned above. Advanced education and training of undergraduate students, PhD students, and a postdoctoral researcher in chemical, mechanical, and electrical engineering in an interdisciplinary and international environment will be conducted, and the mentoring of a young faculty member in chemical engineering will be accomplished.

While many organic compounds are commonly synthesized using high temperature, high pressure, and/or catalytic processes, the application of low temperature electric discharge plasma processes to perform organic synthesis has the potential to improve energy efficiency and to affect chemical selectivity and yield through spatial and temporal control of the plasma. In order to introduce functionality into hydrocarbons, for example OH groups, this project deals with reactions initiated in low temperature plasma exposed to small droplets of organic liquids. This work will advance our understanding of organic gas-liquid reactions in electrical discharge plasma where the liquid droplets are exposed to the plasma environment under ambient temperature and pressure conditions such that they are not evaporated. The research involves the synthesis of a wide range of organic compounds starting with saturated and unsaturated hydrocarbon liquids that are sprayed into the reactor as small droplets. The pure organic droplets will flow into the low temperature and low power plasma where vapor and interfacial reactions occur. In the case of saturated hydrocarbons, hydroxylation reactions to form alcohols will be investigated with emphasis on hydrocarbons with 6 to 10 carbons. Hydroxyl radicals will be formed from small amounts of water and or hydrogen peroxide vapors added to the flowing gas stream. In the case of unsaturated hydrocarbons hydrogenation reactions will be investigated with hydrogen mixed in an argon carrier. Unsaturated hydrocarbons with 6 to 10 carbons as well as selected oils will be studied. In both cases selectivity and yields will be analyzed as functions of the various reactor properties including gas and liquid flow rates and composition, pulsed input power and frequency, and electrode geometry. The general working hypothesis that will be tested and analyzed is that reaction selectivity and yield for plasma reactions of organic compounds from organic liquid droplets can be controlled through variation of plasma and reactor operating conditions. It is anticipated that the reaction products that are soluble in the organic liquid phase will be favored through a mechanism found previously for hydrogen peroxide generation from liquid water droplets whereby liquid soluble products preferentially accumulate in the liquid phase where they are protected from plasma degradation in the surrounding gas. In general, the project seeks to develop a new way to introduce functionality into organic compounds in the liquid phase through spatial and temporal control of the plasma.

This project will develop fundamental knowledge on how plasma in gas-liquid environments leads to the formation of various synthetic organic compounds. Understanding of how such reactions occur is important for the design and operation of chemical reactors that can be used in practical applications to make many useful compounds. For example various alcohols can be made from hydrocarbons in such systems, and this work will have impact on a range of other applications of plasma processes used in material and chemical synthesis and fuels processing. This work is expected to lead to significant advances in our understanding and further development of plasma chemistry with potential impact on the production of valuable organic compounds efficiently from various liquid hydrocarbon sources.

This project seeks to develop plasma gas-liquid reactors to produce chemical disinfectants (e.g., hydrogen peroxide and hydroxyl radicals) through plasma formation. Previous support from NSF has provided knowledge of the basic chemical reactions and the mechanisms for the formation of reactive species including hydroxyl radicals and hydrogen peroxide in small laboratory scale reactors where non-thermal plasma contacts with liquid water. The research team has discovered that higher efficiencies can be obtained when plasma formed in the gas phase contacts a flowing liquid film or an aerosol of water droplets and used this to develop a reactor system. The reactor system developed is quite simple, durable, and robust. While it is currently of relatively small laboratory scale, we expect that the scale up can be addressed so that the system can have a potential impact on the market for small processing plants and perhaps personal use where portability and low unit expense are needed.


The development of new technologies for disinfection, water cleaning, and chemical oxidation can address many public health and environmental problems as well as improve industrial efficiency.
Small scale efficient gas-liquid plasma reactors may find wide use in a variety of such applications.

1702166
PI: Locke, Bruce

The major aim of the proposed work is to experimentally investigate the sustainable chemical production of nitrate and hydrogen peroxide using a gas-liquid non-thermal plasma reactor. This project also seeks to advance the understanding of the design principles of gas-liquid plasma reactors for chemical synthesis. The underlying theme of this proposal is that providing farmers a way to produce nitrogen fertilizer and hydrogen peroxide pesticide locally from sustainable resources, e.g., water, air, and solar energy, in a green chemical process, is an ideal approach to both reducing the environmental impact of fertilizer production and improving the productivity and profit margin of farmers. This project will advance sustainability in chemical reaction engineering through reduction in utilization of petroleum feedstocks for fertilizer and pesticide production.

The proposed research aims to develop a detailed analysis of how non-thermal plasma reactors can be utilized to form nitrate and other species. In the plasma reactor the plasma discharge channels form on, and propagate along, the interface between a flowing gas and a flowing liquid. The reactor design principles to be developed include determination of how plasma properties interact with reactor characteristics and electrical conditions to facilitate synthetic chemical reactions involving nitrogen oxides. The project has three specific aims directed to three major hypotheses. The first specific aim involves the analysis of the chemical reaction mechanisms, and the major hypothesis is that the primary reaction pathway for nitrate formation is through hydroxyl radical reactions. The second specific aim deals with the analysis of the plasma properties and power supply characteristics, and determination of how these properties interact and affect the chemical reaction pathways. The major hypothesis is that nitrate formation efficiency can be controlled by variation of the plasma temperature, electron density, and input power characteristics (pulse power, voltage, frequency). The third specific aim deals with the analysis and development of novel chemical reactor design features for improved performance. The major hypothesis is that modifications of the internal geometry of the gas-liquid plasma reactor (including channel size and nozzle diameter), which affect the surface area, gas and liquid residence times, and plasma contacting, can affect the formation of nitrate via effects on formation of key reactive species including hydroxyl radicals. Outreach activities through the Challenger Center of the FAMU-FSU College of Engineering are proposed and will include presentations and learning modules about plasma applications and topics related to green chemical synthesis and agriculture.

Non-thermal plasmas are low-temperature, atmospheric-pressure ionized gases that are generated by high-voltage electric discharges. When these plasmas are in contact with liquid water, free radical species are formed that effectively decompose toxic compounds or transform organic waste into value-added products. While non-thermal plasmas alone can be used to completely degrade target pollutants into mineralized products, the total electrical power required may make the process economically nonviable. Biological treatment processes, on the other hand, can completely transform some chemical waste species with greatly reduced power demands. However, these processes are limited to biodegradable compounds and may require lengthy processing times. Previous work by this research team demonstrated that the sequential combination of using a plasma reactor to initiate the breakdown of waste compounds followed by a bioreactor to complete the process can lead to significant energy savings. It was also found, however, that the slower bioreactor dynamics results in a mismatch in time scales that ultimately led to very large reactor systems. To overcome this problem, in this study microbial cells will be genetically engineered to: a) survive in the liquid water contacting the non-thermal plasma, and b) increase enzyme production so that the rates of the biological reaction pathways compare to those of the plasma. This matching of the two process time scales will make possible the design and operation of integrated, compact, and energy efficient plasma-bioreactor systems for degrading hazardous and toxic compounds from wastewater streams or to produce useful compounds from waste materials. Fundamental knowledge on coupling a non-biological (abiotic) system such as the non-thermal plasma reactor with the cellular metabolism of a bacterium also will be generated by this work.

This project seeks to develop non-thermal plasma gas-liquid bioreactors, research that couples plasma chemistry and chemical reaction engineering with bioengineering. Plasma reactions occur over time scales of less than 1 second while conventional bioreactors often operate on time scales of hours to days to weeks. These large differences in time scales suggest that it may be possible to attain greater efficiency and reaction process synergy by coupling non-thermal plasma to bioreactors containing microbes bioengineered for both plasma resistance and specific metabolic tasks. The overall goal of the proposed work is to test the hypothesis that microbes resistant to the plasma-produced oxidizing compounds can be genetically engineered to perform other useful biochemical transformations within the reactive environment of gas-liquid non-thermal plasma reactors. Plasma resistant E. coli will be engineered to enhance their inherent capacity to metabolize carboxylic acids, specifically glycolic, formic and oxalic acids. Likewise, the plasma reactor will be engineered to promote effective contact between the cells and the gas-liquid plasma environment. The specific hypotheses of this proposal are: 1) that the newly developed cells will be able to function while exposed to the plasma, and 2) the incorporation of these cells in the plasma reactor will lead to a faster overall mineralization of a target organic compound. The first practical applications to be investigated in this work involve treatment of toxic and difficult to biodegrade organic compounds. The demonstration that microbes can be created to perform useful chemical transformation within the highly oxidizing plasma environment will constitute a novel example of the effective use of electrical energy in chemical processing.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.