Part 3. Texts on interdisciplinary research for abstracting and annotating
Interdisciplinary research (IDR) now receives a great deal of attention because of the rich, creative contributions it often generates. But a host of factors — institutional, interpersonal, and intellectual — also make a daunting challenge of conducting research outside one's usual domain. This selection of the texts on interdisciplinary research is our brief guide to the most effective avenues for collaborative and integrative research in different spheres of knowledge.
It provides answers to questions such as what the best way is to conduct interdisciplinary research on topics related to humanitarian issues. Which are the most successful interdisciplinary research programs in these areas? How do you identify appropriate collaborators? How do you find dedicated funding streams? How do you overcome peer-review and publishing challenges? The selection outlines the lessons that can be taken from the IDR study, and presents a series of informative texts revealing the most successful interdisciplinary research ideas and programs. These programs provide a variety of models of how best to undertake interdisciplinary research.
TASKS
· Write synopses and/or annotations in Russian for each of the texts referring to the guidelines for synopses and annotations (appendix 10).
· Discuss the benefits of interdisciplinary research and the central strategies required to achieve them.
· Propose interdisciplinary research in your sphere of knowledge.
Carbon nanotubes: strengths, weaknesses, opportunities and threats
NANO Magazine, Wednesday, 13 October 2010, Issue 20 (http://www.nanomagazine.co.uk/)
Carbon nanotubes hold great promise for adding functionality, conductivity and strength to many existing and future products. For that reason they've become a hot topic for industry, with promised applications across a broad range sectors.
What are Carbon nanotubes?
Carbon nanotubes (CNTs) are allotropes of carbon. A single wall carbon nanotube is a one-atom thick sheet of graphite (called graphene) rolled up into a seamless cylinder with diameter of the order of a nanometer. This results in a nanostructure where the length-to-diameter ratio exceeds 10,000.
Such cylindrical carbon molecules have novel properties that make them potentially useful in many applications in nanotechnology, electronics, optics and other fields of materials science. They exhibit extraordinary strength and unique electrical properties, and are efficient conductors of heat. Inorganic nanotubes have also been synthesized. Nanotubes are members of the fullerene structural family, which also includes buckyballs. Whereas buckyballs are spherical in shape, a nanotube is cylindrical, with at least one end typically capped with a hemisphere of the buckyball structure. Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers (approximately 50,000 times smaller than the width of a human hair), while they can be up to several millimeters in length.
There are two main types of nanotubes: single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs). Single-walled carbon nanotubes consist of one graphite sheet tube of carbon atom hexagons, while multi-walled carbon nanotubes are characterized by multiple concentric tubes both have a diameter of 1 to 100 nanometres, but average at just a few nanometres. Although not a hollow tube, carbon nanofibers (CNF) represent a third type of tubular structure. The ends of nanotubes are either open or capped with fullerenes.
The nature of the bonding of a nanotube is described by applied quantum chemistry, specifically, orbital hybridization. The chemical bonding of nanotubes are composed entirely of sp2 bonds, similar to those of graphite. This bonding structure, which is stronger than the sp3 bonds found in diamond, provides the molecules with their unique strength. Nanotubes naturally align themselves into "ropes" held together by Van der Waals forces. Under high pressure, nanotubes can merge together, trading some sp2 bonds for sp3 bonds, giving great possibility for producing strong, unlimited-length wires through high-pressure nanotube linking.
They are not unlike other carbon materials, such as diamond or the carbon black that can be found in pencils or car tyres. They have a completely different structure, however, which gives them interesting and very promising properties. Normal graphite is built of sheets with a honeycomb structure of carbon atoms. These sheets are very strong, stable and flexible, but adjoining sheets lack a strong cohesion. In nanotubes, however, these sheets are larger and are “rolled-up” to form long, thin spiral patterns. The significant interest in the production, research and development of carbon nanotubes stems from the unique chemical, mechanical, and physical properties inherent in these materials as. These desired properties include high tensile strength, high electric and thermal conductivity, lightweight, high surface area per gram, advantages in hydrogen storing and catalyzing, absorbency, and flexibility.
The tensile strength of single-walled nanotubes is 100 times greater than that of steel, at only one sixth of steel weight. In terms of thermal conductivity, carbon nanotubes at 1,200-3,000 W/mK exceed that for diamonds at 700-2,000 W/mK. Because of these properties, many researchers and product developers have been attracted to carbon nanotubes for a broad array of potential applications including composites, displays, sensors, fuel and solar cells, batteries, and pharmaceutical materials.
Production and Synthesis
The Chemical Vapor Deposition (CVD) technique is the most commonly used for making nanotubes. Companies such as CNRI, Nanocyl, NanoLab, Nanoamor, and Shenzhen Nanotech use CVD; MER, Nanocarblab, NanoLedge use arc discharge; ILJIN uses both CVD and arc discharge. The production methods have not yet been mastered and thus nanotubes have yet to be produced in mass quantities. Some SWNT producers may be moving away from the older methods and using fluidized beds and other high throughput methods, in order to scale production with relatively low costs.
Raymor Industries utilises a hybrid of existing CVD and Arc processes which uses specially designed plasma torch (design cannot be revealed for competitive reasons) to explode molecules in highly efficient way. It is a clean process; there is no emission of toxic gas. Hydrogen molecules can be recycled for environmental purposes. The process creates a large quantity of nanotubes compared to the original mass. The single-walled nanotubes formed are of a high quality and high purity.
Depending on the method of synthesis, impurities in the form of catalyst particles, amorphous carbon, and non-tubular fullerenes are also produced. Thus, subsequent purification steps are required to separate the tubes from other forms of non-tubular carbon. Purification involves chemical processes like acid reflux, filtration, centrifugation, and repeated washes with solvents and water. Typical nanotube diameters range from 0.4 to 3 nm for SWNTs, and from 1.4 to more than 100 nm for MWNTs. It has been established that a nanotube's properties can be tuned by changing its diameter.
Market Hype
The main driving force for investment in carbon nanotubes R&D is their promise to offer improvements in materials capabilities across a wide range of applications. This is of huge strategic importance to sectors which historically leverage technological advancements. Carbon nanotubes enable radical design changes for a wide variety of markets by permitting combinations of properties not previously possible in materials design and affording multi-functionality for increased efficiency. The challenge is translating the excellent combination of nanotubes properties on the nanoscale to structural properties on the macroscale. Current hindrances include: inconsistent quality of carbon nanotubes supply; dispersion; characterization of carbon nanotubes nanocomposites; and scaling down processing equipment to work around the low CNT supply.
The majority of current global revenues for carbon nanotubes are generated by relatively large-scale manufacturing of bulk materials for applications where electrical conductivity, increased mechanical performance and flame retardancy are primary design drivers. Composites, field emission devices and batteries are the most prominent and commercially viable current applications. Next generation products will incorporate sensing capabilities and multi-functionality and lead to greatly increased revenues over the next 3-10 years. Prices will also fall over the next few years as large companies begin to produce commercial-scale volumes of nanotubes. Large multi-nationals such as Arkema, Bayer and Showa Denko have significantly ramped up production levels; companies in China and Russia are also producing significantly cheaper nanotubes.
Main markets at present for nanotubes are aerospace, automotive, defence and electronics & data storage; generally as multi-purpose compound enhancers. In aerospace, nanotubes already find application as additives for ESD and EMI shielding; as electrostatic coatings and component reinforcement additives in the automotive sector; in various defence applications; and as conductive polymers and composites for field emission displays. This represents the first generation of nanotubes products; the next generation will be based on controlled fabrications leading to multi-functional and sensory capabilities.
The electronics and data storage market is likely to see the biggest penetration to 2015, with the performance enhancing properties of carbon nanotubes allowing electronics manufacturers to meet demanding market needs across a variety of applications. Their incorporation into the displays applications will also increase demand, with a conservative revenue forecast of $1.07 billion by 2015.
There is a great demand in the market for carbon nanotubes, especially in the electronics and polymers sectors; production and price are restraints at present but this is changing. A kilogram of carbon nanotubes used to cost up to $1,000, but now, as a result of targeted research and development activities, companies has managed to significantly lower the price-per-kilogram, thereby enabling the development of new, industrial applications. For example, the automotive industry will soon be able to reduce the cost of painting plastic fenders: adding just minimal amounts makes the semi-finished parts electrically conductive, and this new material property supports more efficient and environmentally friendly coating processes based on counter charged, solvent-free powder coating particles.
In most cases, CNTs are used as an additive to add value to existing products or to develop new products such as Field Emission Displays displays. The advantage as an additive is usually an enhancement of the properties with a low loading of nanotubes. This low loading also offers new possibilities like transparency in coatings. Other advantages can be lower manufacturing cost using a CNT-based technology.
One of the biggest challenges facing the carbon nanotube producers is the ability to obtain significant quantities of the desired type of carbon nanotube. High throughput experimentation is one possible approach that holds promise for searching the best catalyst for growing the desired nanotube. Other issues that assume significant importance is identifying the most likely nanomaterial and then setting up a large infrastructure for a scalable mass-manufacturing process. Some techniques that are used to build electronic components with carbon nanotubes are inappropriate for mass production.
Expensive, small scale production of nanotubes as well as clumping, lack of binding to the bulk material, and temperature effects are therefore key barriers to their application in the industry. Although there are challenges ahead, carbon nanotubes have opened up a host of practical applications in the nanometre scale.
Applications of CNTs
Examples of carbon nanotube-based applications are illustrated in the roadmap. The main markets for nanotubes at present are aerospace, automotive, defence and electronics & data storage; generally as multi-purpose compound enhancers. In aerospace, nanotubes already find application as additives for ESD and EMI shielding. The automotive sector uses them as electrostatic coatings and component reinforcement additives. in various defence applications; and as conductive polymers and in consumer electronics such as composites for FED. This represents the first generation of nanotubes products; the next generation will be based on controlled fabrications.
The ITC market is likely to see the biggest penetration to 2015, with the performance enhancing properties allowing electronics manufacturers to meet demanding market needs. Their incorporation into the displays market will increase demand by 2010, with a revenue forecast in the ITC market of $1.096 billion by 2015. While in the longer run, electronics will continue to dominate nanotube applications as broader use in semiconductors occurs, strong opportunities are also expected from CNT-based products using chemical vapour deposition technology.
It seems the possibilities for carbon nanotubes will continue to develop in the future as research continues to develop on their possibilities. Researchers at the University of Cincinnati (UC) have developed a process to build extremely long aligned carbon nanotube arrays. They've been able to produce 18-mm-long carbon nanotubes which might be spun into nanofibers.
New studies on the strength of these submicroscopic cylinders of carbon from the University of Southern California, LA, indicate that on an ounce-for-ounce basis they are at least 117 times stronger than steel and 30 times stronger than Kevlar, the material used in bulletproof vests and other products. That's twice as strong as they were once thought to be – it seems the future's brighter and stronger for carbon nanotubes.
Prizewinning nanoparticle based ‘sharkskin’ for aeroplanes, ships and wind energy plants
NANO Magazine, 2010, Issue 18 (http://www.nanomagazine.co.uk/)
To lower the fuel consumption of airplanes and ships, it is necessary to reduce their flow resistance, or drag. An innovative paint system makes this possible. This not only lowers costs, it also reduces CO2 emissions.
The inspiration – and model – for the paint‘s structure comes from nature: The scales of fast-swimming sharks have evolved in a manner that significantly diminishes drag, or their resistance to the flow of currents. The challenge was to apply this knowledge to a paint that could withstand the extreme demands of aviation. Temperature fluctuations of -55 to +70 degrees Celsius; intensive UV radiation and high speeds. Yvonne Wilke, Dr. Volkmar Stenzel and Manfred Peschka of the Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research IFAM in Bremen developed not only a paint that reduces aerodynamic drag, but also the associated manufacturing technology. In recognition of their achievement, the team is awarded the 2010 Joseph von Fraunhofer Prize.
The paint involves of a sophisticated formulation. An integral part of the recipe: the nanoparticles, which ensure that the paint withstands UV radiation, temperature change and mechanical loads, on an enduring basis. „Paint offers more advantages," explains Dr. Volkmar Stenzel. „It is applied as the outermost coating on the plane, so that no other layer of material is required. It adds no additional weight, and even when the airplane is stripped – about every five years, the paint has to be completely removed and reapplied – no additional costs are incurred. In addition, it can be applied to complex three-dimensional surfaces without a problem." The next step was to clarify how the paint could be put to practical use on a production scale. „Our solution consisted of not applying the paint directly, but instead through a stencil," says Manfred Peschka. This gives the paint its sharkskin structure. The unique challenge was to apply the fluid paint evenly in a thin layer on the stencil, and at the same time ensure that it can again be detached from the base even after UV radiation, which is required for hardening.
Yvonne Wilke, Dr. Volkmar Stenzel and Manfred Peschka engineered a paint system that can reduce the fl ow resistance of airplanes and ships. That saves fuel.
When applied to every airplane every year throughout the world, the paint could save a volume of 4.48 million tons of fuel. This also applies to ships: The team was able to reduce wall friction by more than five percent in a test with a ship construction testing facility. Extrapolated over one year, that means a potential savings of 2,000 tons of fuel for a large container ship. With this application, the algae or muscles that attach to the hull of a ship only complicate things further. Researchers are working on two solutions for the problem. Yvonne Wilke explains: „One possibility exists in structuring the paint in such a way that fouling organisms cannot get a firm grasp and are simply washed away at high speeds, for example. The second option aims at integrating an anti-fouling element – which is incompatible for nature."
Irrespective of the fuel savings, there are even more interesting applications – for instance, with wind energy farms. Here as well, air resistance has a negative effect on the rotor blades. The new paint would improve the degree of efficiency of the systems – and thus the energy gain.
Pyrolysis and gasification of food waste: syngas characteristics and char gasification kinetics
I.I. Ahmed, A.K. Gupta
The Combustion Laboratory, University of Maryland, Department of Mechanical Engineering, College Park, MD 20742, United States
Keywords: Food waste gasification; Char gasification kinetics; Catalytic effect of ash; Compensation effect
Abstract
Characteristics of syngas from the pyrolysis and gasification of food waste has been investigated. Characteristic differences in syngas properties and overall yields from pyrolysis and gasification were determined at two distinct high temperatures of 800 and 900 oC . Pyrolysis and gasification behavior were evaluated in terms of syngas flow rate, hydrogen flow rate, output power, total syngas yield, total hydrogen yield, total energy yield, and apparent thermal efficiency. Gasification was more beneficial than pyrolysis based on investigated criteria, but longer time was needed to finish the gasification process. Longer time of gasification is attributed to slow reactions between the residual char and gasifying agent. Consequently, the char gasification kinetics was investigated. Inorganic constituents of food char were found to have a catalytic effect. Char reactivity increased with increased degree of conversion. In the conversion range from 0.1 to 0.9 the increase in reactivity was accompanied by an increase in prexponential factor, which suggested an increase in gasifying agent adsorption rate to char surface. However, in the conversion range from 0.93 to 0.98 the increase in reactivity was accompanied by a decrease in activation energy. A compensation effect was observed in this range of conversion of 0.93–0.98.
Introduction
Dumping food waste in a landfill causes environmental problems. By volume, the dumped landfill waste causes the largest contribution to methane gas production [1]. It causes odor as it decomposes to cause public annoyance in addition to forming germs, and attracting flies and vermin. Another serious problem of food wastes is the generation of landfill leachate. Landfill leachate is liquid that leaks from the landfill and enters the environment. Once it enters the environment the leachate is at risk for mixing groundwater near the site which then transports to some distances. Furthermore it has the potential to add biological oxygen demand (BOD) to the groundwater. BOD measures the rate of oxygen uptake by micro-organisms in a sample of water at a temperature of 20 oC and over an elapsed period of five days in the dark.
Food wastes have high energy content. Consequently, it offers a good potential for feed stock for gasification in power plants. Food waste gasification helps to solve two major problems at the same time. Gasification of food waste reduces landfill problems and efficiency. The results show that food wastes offers a good potential for thermal treatment of the waste with the specific aim of power generation. The average proximate analysis of food wastes is 80% volatile matter, 15% fixed carbon, and 5% ash. The volatile matter can be easily destructed in a relatively short period of time, extending from 8 to 12 min at reactor temperatures from 700 to 1000 oC . Energy recovery from volatile components in food wastes can be recovered using a simple pyrolysis process. However, in order to consume the residual fixed carbon after the pyrolysis, the sample must undergo a gasification process. Gasification of a food waste sample includes a pyrolysis part and a char gasification part. Char gasification reactions are slower than that of pyrolysis and consequently, is the rate limiting step in the overall gasification process.
The ash present in the sample does not react with the gasifying agent. The ash can be collected after cooling and cleaning the syngas, and then recycled for its further use in industrial processes.
Since the char gasification process is the rate limiting step, it is important to quantify the kinetic parameters of char gasification. Char gasification has been investigated by a large number of researchers. Some of the important parameters investigated include the origin of the char sample, gasifying agent, total pressure, variation of partial pressure of gasifying agents, geometric changes of the sample during gasification, and catalyzed char gasification. One of the most important parameters which have been investigated is the catalytic effect of ash content on char gasification.
[Some details are omitted]
Consequently, for a desired feed rate of feedstock into the reactor and for known gasifier operational conditions an accurate reactivity expression will lead to a close estimate of the gasifier size and configuration. If a constant reactivity value is used in reacting flow simulations for feedstock having time dependant reactivity, misleading information on char particles residence time will be obtained.
This will consequently result in a departure gasifier size from the true design size and configuration. For example, if a constant reactivity value is used for chars having ash catalytic effect, such as the case examined here, the designed gasifier size will be over estimated since the reactivity of char was fond to increase with the degree of conversion.
Background
Tancredi et al. [2] investigated the catalytic effect of ash on char gasification for eucalyptus wood chars. The ash content in char was of the order of 1.45% on mass basis. The reactivity of the char increases monotonically with conversion. At low and intermediate conversion, it can be attributed to the increase in surface area as gasification proceeds. At high conversion levels a steeper increase in reactivity has been observed, which cannot be explained by the development of surface area. This region of the reactivity/conversion curves can be better explained as the result of an increase in catalytic effect of the metallic constituents (mainly Na and K) present as inorganic matter in the chars. Here CO2 was used as the gasifying agent. Activation energies determined were found to vary within a narrow range of 230–257 kJ/mol. Arrhenius plots showed parallel lines for different degrees of conversion. Parallel line of Arrhenius plot indicates similar activation energies. The increase in reactivity was mainly due to an increase in pre-exponential factor. In a similar study by Montesinos et al. [3], steam gasification and CO2 gasification of grape fruit skin char were investigated. They also observed an increase in reactivity at high values of conversion. However, a different trend of activation energies values was observed; in the case of CO2 gasification, as the conversion increased, a decrease in activation energy was observed.
On the other hand an increase in activation energy was observed in case of steam gasification. This increase in activation energy was also, observed by Marsh et al. [4]. The decrease in activation energy values in the case of CO2 gasification was accompanied by a decrease in pre-exponential factor as well. This behavior is called the compensation effect [5]. Montesinos et al. obtained a value of isokinetic temperature of 1150 K. The isokinetic temperature is the temperature at which all reactivities are equal for different conversions. An isokinetic temperature of 1449 K was obtained by Dhupe et al. [6] for CO2 gasification using catalyzed sodium lignosulfonate. Feistel et al. [7] found this temperature to be 1425 K, obtained using potassium-catalyzed steam gasification.
[Some details are omitted]
Food wastes, especially which have high percentage of vegetable oil and animal fat, provide a good potential for production of liquid fuels though transesterification. Transesterification is the process of exchanging the organic group R00 of an ester with the organic group R0 of an alcohol. The process is widely used to produce biodiesel fuels from vegetable oils and animal fats. The process is often catalyzed by an acid or a base.
Other than acid or base catalysts, enzyme or heterogeneous catalysts might be used as well. Among the mentioned catalysts, alkali catalysts are more effective. However, if the oil has high free fatty acid (FFA) content, higher than 3% (approximately), acid catalyzed transesterification is used rather than a base catalyst [10,11].
[Some details are omitted]
Experimental
Fig. 1 shows a photograph of the laboratory scale experimental facility used to examine the pyrolysis and gasification of food wastes. Steam is generated from the stoichiometric combustion of hydrogen and oxygen. Steam generated is then introduced into the superheater section to form the gasifying agent at the desired condition. The temperature of the gasifying agent heater is kept at the same temperature as that of the main reactor in which sample material was allowed to undergo gasification. Steam is then introduced into the main reaction chamber that contained the hydrocarbon sample. The syngas flowing out from the main reaction chamber is sub-divided into two paths; one passes to the sampling line while the other is passed through the exhaust system.
Fig. 1. A photograph of the experimental facility.
The bypass line has a non-return valve and a flow meter to assure the desired unidirectional flow out from the reactor. The syngas sample is then introduced to a condenser followed by a low pressure filter and a moister absorber (anhydrous calcium sulfate). This procedure assured that the sample is dry prior to its introduction into a gas analyzer. The filtered and dried syngas is then analyzed using a GC or a mass spectrometer.
[The description of the experiment is omitted]
Results and discussion
The characteristic of syngas from food waste pyrolysis and gasification have been investigated. Food waste is a char-based sample. Results from char-based samples (samples containing volatile matter and char, such as paper [13], cardboard [14,15], woodchips and food waste) follow, qualitatively similar trend. Syngas is characterized by a high flow rate initially, due to pyrolysis, and then followed by a small flow rate which lasts for longer period, which is due to char gasification.
[Some details are omitted]
Conclusions
Gasification yielded enhanced production of syngas, hydrogen and energy as that obtained from pyrolysis. However the time required for gasification is more as compared to pyrolysis. As compared to paper gasification at the same conditions, food waste needed more time to complete the gasification process. Inorganic constituents in food char were found to have a catalytic effect. Char reactivity increased with degree of conversion. In the conversion range from 0.1 to 0.9 the increase in reactivity was accompanied by an increase in pre-exponential factor, suggesting an increase in gasifying agent adsorption rate to char surface. However, in the conversion range from 0.93 to 0.98 the increase in reactivity was accompanied by a decrease in activation energy. A compensation effect was observed in this range of conversion, from 0.93 to 0.98. Isokinetic temperature obtained from Arrhenius plots for X from 0.93 to 0.98 was 1001 oC.
Acknowledgment
This research was supported by the ONR and is support is gratefully acknowledged.
References
[1] <http://www.landfill-gas.com>.
[2] Tancredi N, Cordero T, Mirasol JR, Juan J. CO2 gasification of eucalyptus wood chars. Fuel 1996;75(13):1505–8.
[3] Montesinos FM, Cordero T, Mirasol JR, Rodriguez JJ. CO2 and steam gasification of a grapefruit skin char. Fuel 2002;81:423–9.
[4] Marsh H, Taylor DA, Lander JR. Kinetic study of gasification by oxygen and carbon dioxide of pure and doped graphitizable carbons of increasing heat treatment temperatures. Carbon 1981;19(5):375–81.
[5] Agrawal RK. On the compensation effect. J Therm Anal 1986;31:73–86.
[6] Dhupe AP, Gokarn AN, Doraiswamy LK. Investigations into the compensation effect at catalytic gasification of active charcoal by carbon dioxide. Fuel 1991;70(7):839–44.
[7] Feistel PP, Van Heek KH, Juntgen H, Pulsifer AH. The compensation effect in the steam gasification of coal. Carbon 1976;14(6):363–4.
[8] Gokarn AN, Muhlen HJ. Catalysis of char gasification by mixed lignosulfonates: quantification of role of each component. Fuel 1996;75(1):96–8.
[9] Li S, Cheng Y. Catalytic gasification of gas–coal char in CO2. Fuel 1995;74(3):456–8.
[10] Meher LC, Sagar DV, Naik SN. Technical aspects of biodiesel production by transesterification-a review. Renew Sust Energy Rev 2006;10:248–68.
[References 11-16 are omitted]
BioMedical Engineering OnLine 2010, 9:84 (http://www.biomedical-engineering-online.com)