The interest in nanoscale materials stems from the fact that new properties are acquired at this length scale and, equally important, that these properties * To whom correspondence should be addressed. Phone, 404-8940292; fax, 404-894-0294; e-mail, mostafa.el-sayed@ chemistry.gatech.edu. † Case Western Reserve UniversitysMillis 2258. ‡ Phone, 216-368-5918; fax, 216-368-3006; e-mail, burda@case.edu. § Georgia Institute of Technology. 1025 Chem. Rev. 2005, 105, 1025−1102

Chemistry and properties of nanocrystals of different shapes.

Although problem solving is regarded by most educators as among the most important learning outcomes, few instructional design prescriptions are available for designing problem-solving instruction and engaging learners. This paper distinguishes between well-structured problems and ill-structured problems. Well-structured problems are constrained problems with convergent solutions that engage the application of a limited number of rules and principles within well-defined parameters. Ill-structured problems possess multiple solutions, solution paths, fewer parameters which are less manipulable, and contain uncertainty about which concepts, rules, and principles are necessary for the solution or how they are organized and which solution is best. For both types of problems, this paper presents models for how learners solve them and models for designing instruction to support problem-solving skill development. The model for solving well-structured problems is based on information processing theories of learning, while the model for solving ill-structured problems relies on an emerging theory of ill-structured problem solving and on constructivist and situated cognition approaches to learning.

/pdf/instructional-design-models-for-well-structured-and-ill-1hjtyfvlbr.pdf

Instructional Design Models for Well-Structured and Ill-Structured Problem-Solving Learning Outcomes

Optically excited plasmonic nanoparticles can activate chemical reactions on their surfaces. The underlying physical mechanisms responsible for the chemical activity and advances in photocatalysis on plasmonic metallic nanostructures are discussed. The strong interaction of electromagnetic fields with plasmonic nanomaterials offers opportunities in various technologies that take advantage of photophysical processes amplified by this light–matter interaction. Recently, it has been shown that in addition to photophysical processes, optically excited plasmonic nanoparticles can also activate chemical transformations directly on their surfaces. This potentially offers a number of opportunities in the field of selective chemical synthesis. In this Review we summarize recent progress in the field of photochemical catalysis on plasmonic metallic nanostructures. We discuss the underlying physical mechanisms responsible for the observed chemical activity, and the issues that must be better understood to see progress in the field of plasmon-mediated photocatalysis.

http://www-nature-com-443.webvpn.bjmu.tsg211.com/articles/nmat4281.pdf

Photochemical transformations on plasmonic metal nanoparticles

Recent advances in molecular biology have extended our understanding of the metabolic processes related to microbial transformation of petroleum hydrocarbons. The physiological responses of microorganisms to the presence of hydrocarbons, including cell surface alterations and adaptive mechanisms for uptake and efflux of these substrates, have been characterized. New molecular techniques have enhanced our ability to investigate the dynamics of microbial communities in petroleum-impacted ecosystems. By establishing conditions which maximize rates and extents of microbial growth, hydrocarbon access, and transformation, highly accelerated and bioreactor-based petroleum waste degradation processes have been implemented. Biofilters capable of removing and biodegrading volatile petroleum contaminants in air streams with short substrate-microbe contact times ( 2 S and sulfoxides from petrochemical waste streams. Microbes also have potential for use in removal of nitrogen from crude oil leading to reduced nitric oxide emissions provided that technical problems similar to those experienced in biodesulfurization can be solved. Enzymes are being exploited to produce added-value products from petroleum substrates, and bacterial biosensors are being used to analyze petroleum-contaminated environments.

Recent Advances in Petroleum Microbiology

Discrete particle simulation of particulate systems: A review of major applications and findings

The treatment of smectites with a hydroxy-A1 polymer produced chemically modified clays that had much greater affinities for chlorinated dioxins and biphenyls than untreated clays. For hydroxy- Al-treated kaolinite, the high affinity for chlorinated dioxins is thought to have arisen from an interaction between the hydroxy-A1 polymer bound to the clay and the chlorinated dioxin in solution. Thus, the adsorption of dioxins from aqueous solution by hydroxy-Al-treated clays is similar to the adsorption of reactants from the gas phase by metals supported on mineral oxides during catalysis. In both systems, the essentially inert mineral oxide support effectively disperses the active adsorptive agent. At the con- centrations of octachlorodioxin used in this study (-< 5 ppb), hydroxy-Al-montmorillonite had a distri- bution coefficient of 90,000 (ml/g), corresponding to about 95% removal efficiency of the dioxin from solution per batch. For hexachlorohiphenyl, the distribution coefficient was 30,000 (mi/g), and the removal efficiency was 85%. Key Wards--Adsorption, Biphenyl, Dioxin, Hydroxy-A1, Kaolinite, Pollutant, Smectite.

https://link.springer.com/content/pdf/10.1346/CCMN.1989.0370515.pdf

Dioxon sorption by hydroxy-aluminum-treated clays

This study discusses experimental and modeling results of asphaltene aggregation and deposition using various n-alkanes as precipitants to destabilize asphaltenes from a crude oil. The amount of asphaltenes precipitated as a function of precipitant carbon number and concentration was obtained after monitoring the slow kinetic aggregation process. A geometric population balance was used to estimate the asphaltene–asphaltene collision efficiency during bulk aggregation. The results revealed that, for a fixed volume fraction of precipitant, the collision efficiency decreases with increasing precipitant carbon number, resulting in slower aggregation. The tendency for asphaltenes to deposit was measured using capillary flow experiments under similar conditions. Similar asphaltene deposition behavior was obtained when the results were normalized by the asphaltene solubility and other experimental factors. A modified aggregation model was applied to the results and revealed that the difference between the asphal...

Combined Asphaltene Aggregation and Deposition Investigation

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Dioxon sorption by hydroxy-aluminum-treated clays

Combined Asphaltene Aggregation and Deposition Investigation