bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical Forces Matter in Health and Disease: From Cancer to Tissue Engineering
Authors: Vogel Viola , Sheetz Michael P.
Published: June 2010

Cellular microenvironments control many aspects of cell behavior, differentiation and wound healing. When cells are in an inappropriate environment, they often stop growth or enter an apoptotic pathway. Environment is defined by the biological or engineered matrix, soluble molecules, adjacent cells and physical factors of force and geometry that all act at the nanometer (protein) level. The development of nanotechnology tools has provided new ways to measure the forces and control the geometry spatial in which ligands are presented. In this chapter, we focus on reviewing the effects of mechanical force on cellular functions because it is a critical intensive parameter that dynamically affects cell functions in health and disease. For force transmission, cell adhesion sites must be linked mechanically to the cell cytoskeleton and force‐generating machinery within the cell, as well as to the extracellular matrix (ECM). Forces are processed by specialized adhesive structures that are dynamic as the cells actively bind, stretch and remodel their surroundings. Once formed, the early contacts either mature rapidly or break. We will discuss how forces upregulate the maturation of early cell–matrix junctions and regulate the dynamic interplay between the assembly and disassembly of adhesion sites. Once sufficiently stabilized through recruitment of additional focal adhesion proteins, intracellular traction can generate large forces on the adhesive junctions – forces which are easily visualized as strain applied by cells to flexible substrates. Protein stretching and unfolding plays a central role in the recruitment of proteins to an adhesion site, and in regulating intracellular signaling events, including stretch‐dependent tyrosine phosphorylation. The nanoscale machinery of an adhesion site enables the cell to sense and respond to the spatial patterns of its environment, as well as to its rigidity. In response, cells change their protein expression pattern and assemble and remodel the ECM. This in turn regulates cell motility and many other cellular functions. We will then discuss that many diseases have a mechanical origin or show abnormalities in cellular mechanoresponses, from cancer to cardiovascular disorders, from osteoporosis to other aging‐related diseases. Ultimately, mechanotransduction processes regulate tissue formation, remodeling and healing in native wound sites of tissue engineered scaffolds, as well as how stem cells differentiate and whether cells derail and evolve into cancer cells or other disease conditions.
Stem Cells and Nanomedicine: Nanomechanics of the Microenvironment
Authors: Rehfeldt Florian , Engler Adam J. , Discher Dennis E.
Published: June 2010

The various cells in our body interact with different micro/nano‐environments that depend on the tissue as well as the niche within the tissue. Although for many – if not most – cells the environment is maintained throughout the cell's lifetime, there are certainly some events that perturb both the physical and biochemical properties of the cell's surrounding; these events include wounding, regeneration, inflammation and cancer. There are also some cells – particularly adult stem cells – that migrate to and thus probe very different tissues within the body. In this chapter we discuss micro/nano‐elasticity measurements of tissue, and provide a summary of results obtained with adult human mesenchymal stem cells that most likely encounter a range of very differentmechanochemicalmicroenvironments. The interactions of cells with their surroundings reveal complex feedback loops coupled to soluble growth factor pathways, with implications for important new approaches to regenerative medicine.
Bone Nanostructure and its Relevance for Mechanical Performance, Disease and Treatment
Authors: Fratzl Peter , Gupta Himadri S. , Roschger Paul , Klaushofer Klaus
Published: June 2010

The remarkable mechanical properties of bone are due to its hierarchical structure which is optimized at all levels of hierarchy. At the lowest level, bone is a nanocomposite of collagen and mineral particles. The quality of this material is crucial for the mechanical performance of bone as a whole. In this chapter we review the structure and composition of bone material at the nanoscale, and report several examples on how bone material may be affected by disease or treatment strategies.
Nanoengineered Systems for Tissue Engineering and Regeneration
Authors: Khademhosseini Ali , Rajalingam Bimal , Jinno Satoshi , Langer Robert
Published: June 2010

The ability to generate and transplant functional tissue constructs, through the artificial engineering of biological tissues, may provide a solution for a number of biomedical challenges. However, several clinically viable tissue engineering products having been created, limitations such as the lack of a suitable cell source and the inability to generate three‐dimensional (3‐D) tissues with sufficient complexity and functional properties, greatly hinders us from realizing the full potential of tissue engineering. Recently, nanotechnology has been used for tissue engineering by generating materials and devices that can mimic the organization and structure of native tissues or direct cell function. In this chapter we will discuss the use of nanoengineered systems and nanomaterials for generating 3‐D tissues, for controlling stem cell differentiation, as well as analyzing the resultant constructsin vitroandin vivo. The application of nanotechnology for biological studies, as well as drug screening and diagnostics, will also be discussed.
Self‐Assembling Peptide‐Based Nanostructures for Regenerative Medicine
Authors: Capito Ramille M. , Mata Alvaro , Stupp Samuel I.
Published: June 2010

Biomaterials designed at the molecular and supramolecular levels to interact with cells, biomolecules such as growth factors and biopolymers, and pharmaceuticals will all have a profound impact on technologies targeted towards the regeneration of damaged tissues as a result of trauma, disease or genetic defects. Advances in materials science, chemistry, genomics and stem cell biology will all contribute towards the development of therapies leading to the successful regeneration of specific tissues. Regenerative medicine therapies should be minimally invasive, and thus the notion of cell scaffolds that self‐assemble from injected liquids is highly attractive for clinical translation. In this regard, self‐assembling materials will play a key role in future regenerative medicine technologies. In this chapter we focus on the current development of injectable, self‐assembling scaffolds that can be designed to provide a biomimetic and bioactive environment to stimulate cell‐signaling pathways that are critical in the regenerative process. We also describe the use of self‐assembling coatings to render traditional inert materials more bioactive and biocompatible, especially in orthopedic applications.
Spin‐Polarized Scanning Tunneling Microscopy
Authors: Getzlaff Mathias
Published: June 2010

This chapter describes the enormous experimental progress in spin‐polarized scanning tunneling microscopy (SP‐STM), which allows magnetically sensitive imaging with ultra‐high resolution down to the atomic scale. The fundamentals of SP‐STM are introduced on the basis of planar tunnel junctions for different electrode materials being superconductors, optically excited GaAs and ferromagnets. It is shown that both ferromagnets and antiferromagnets are suitable tip materials for SP‐STM. Appropriate tip designs and modes of operations are discussed for both types of material. The results of recent laterally resolved measurements performed with different magnetic probe tips and different modes of operation are reviewed. In addition, the limits of this ultimate lateral resolution and the influence of an external magnetic field on the imaging process are discussed. The examples discussed range from bulk material to 2‐D systems such as surfaces, thin films and nanoparticles, and to 1‐D systems such as nanowires. The magnetic properties of individual atoms are also presented.
Nanoscale Imaging and Force Analysis with Atomic Force Microscopy
Authors: Hölscher Hendrik , Schirmeisen André , Fuchs Harald
Published: June 2010

The atomic force microscope – sometimes also referred to as the scanning force microscope – has developed into the most widespread tool used in nanotechnology. The instrument and technique were invented by Binniget al. in 1986, and are today used not only in physical, chemical, biological and medical research laboratories, but also in many companies for tasks such as product development and routine quality control. The success of the technique is based on its high‐resolution imaging capabilities in combination with its versatility, making it possible to image surfaces down to the atomic scale. Due to its universality, atomic force microscopy can be applied to a large variety of samples, and adapted to many different environments (gaseous, liquid, or vacuum). The atomic force microscope can be operated in different modes, which can be categorized as static and dynamic. Here, an introduction is provided of the basic concepts of the two modes, and details applications under different environmental conditions are presented. Some practical issues for the experimentalist are highlighted, while special care is taken to explain the quantitative relationship between experimental parameters and physical magnitudes.
Probing Hydrodynamic Fluctuations with a Brownian Particle
Authors: Jeney Sylvia , Lukic Branimir , Guzman Camilo , Fórró László
Published: June 2010

In this chapter we demonstrate the use of optical trapping interferometry to track and study the motion of a Brownian particle down to hydrodynamic timescales, where the response of the surrounding viscous fluid becomes dominant. A Brownian particle rapidly explores its surrounding medium that in turn alters its trajectory, and hence functions as a probe of its local environment. After an introduction to fundamental aspects of the theory of Brownian motion, which are very often ignored by experimentalists, we describe our instrument with a particular emphasis on position detection, data acquisition and analysis. Comparing the suitable theory with our data allows calibration of our instrument and quantification of the influence of experimentally relevant parameters, such as the trapping force constant, the fluid properties and the Brownian particle itself. The presented approach should ultimately open up the possibility of using a Brownian probe as a direct reporter of even more complex viscoelastic and/or heterogeneous media.
Nanoscale Thermal and Mechanical Interactions Studies using Heatable Probes
Authors: Gotsmann Bernd , Lantz Mark A. , Knoll Armin , Dürig Urs
Published: June 2010

The use of heatable probes in scanning probe microscopy allows the effect of temperature to be studied in combination with the mechanical interaction of the probe tip with a sample surface. Using nanometer‐scale sharp tips, the thermal and thermomechanical properties of solids can be determined locally down to nanometer scale. In this chapter we present a review of heatable probe types, and discuss some of the most prominent applications of these devices. Scanning thermal imaging is described first, followed by a detailed analysis of local heat flow through heated tips in contact with a surface. Nanoindentation of polymers with heated tips is used to uncover fundamentals of thermomechanical interaction with polymers on a small scale. This is described in terms of yielding and deformation kinetics. Finally, patterning applications are discussed, such as thermomechanical probe‐storage using nanoindentation, nanotribology and nanolithography utilizing heated‐tip‐assisted deposition and removal of material.
Materials Integration by Dip‐Pen Nanolithography
Authors: Lenhert Steven , Fuchs Harald , Mirkin Chad A.
Published: June 2010

Dip‐pen nanolithography (DPN) is a versatile tool for nanotechnology that enables the resolution of electron‐beam lithography, integration capabilities typical of inkjet printing, and a high throughput comparable to microcontact printing. By using the tip of an atomic force microscope as an ultra‐sharp pen, DPN represents a constructive method of scanning probe lithography that can be carried out in a massively parallel fashion. This chapter introduces the fundamental concepts in DPN technology, with a focus on aspects that enable materials integration. Theoretical models of ink transport are discussed, and a variety of experimental methods presented. The concept of a driving force is explained, along with various methods for controlling that driving force, both by ink–substrate combinations, humidity and the application of external fields. Various approaches to tip coating are explained and suitable characterization methods presented. Finally, examples of unique applications of materials integration by DPN will be described that cannot be achieved by any other method, including templates, combinatorial chemistry and biological arrays.
Cryoelectron Tomography: Visualizing the Molecular Architecture of Cells
Authors: Thomas Dennis R. , Baumeister Wolfgang
Published: June 2010

Electron tomography can generate three‐dimensional reconstructions of the macromolecular machinery of the cellin situwith nanoscale resolution. The principles of electron tomography are the same as those applied to the analysis of isolated single complexes. In recent years technological advances have made it possible to apply tomography to ice‐embedded biological material (‘cryotomography’), thereby ensuring a close‐to‐life preservation of the sample. Tomographic reconstruction of biological samples embedded in vitreous ice, combined with advanced computational methods for their interpretation, provides the possibility of comprehensively mapping the macromolecular architecture inside organelles and cells. Thus we can begin to visualize macromolecular machines at work in their natural enviroment.
Nanoplasmonics
Authors: Steiner Gerald
Published: June 2010

Metallic nanostructures are able to manipulate light on a wide scale of and far below the diffraction limit of the classical optic. The overall process is the excitation of surface plasmons localized in and around metallic nanostructures, recently termed as ‘nanoplasmonic’. Localized surface plasmons are collective charge oscillations in metal clusters of few nanometers in size. Their unique optical properties enable many applications, ranging from the enhancement of scattering processes and light absorption to biosensing on the single molecular level or high‐resolution imaging. This chapter describes briefly the fundamentals of the excitation of localized surface plasmons in single clusters, as well as the interaction between clusters. Some exciting new applications in biosensing, together with the well‐established methods of surface‐enhanced spectroscopy, are described.
Impedance Analysis of Cell Junctions
Authors: Wegener Joachim
Published: June 2010

The term ‘cell junctions’ comprises not only molecular contacts between neighboring cells within a cell assembly but also contacts between cells and the extracellular matrix. Cell junctions are pivotal for many fundamental physiological processes. Structural studies of cell junctions have traditionally been performed using light or electron microscopy, after appropriate labeling. This chapter describes the use of impedance analysis for a more functional and label‐free analysis of cell junctions. The basics of electrical impedance measurements are introduced before examples are described that demonstrate the potency of the approach in monitoring cell junctions.
Catalysis Involving Fluorous Phases: Fundamentals and Directions for Greener Methodologies
Authors: Gladysz John A.
Published: June 2010

This article briefly reviews the fundamentals of fluorous chemistry, with an emphasis on aspects most relevant to catalysis. The development of “greener” fluorous solvents and ponytails (phase tags) is described. Protocols that minimize the use of fluorous solvents are emphasized. Some of these exploit the highly temperature dependent solubilites of fluorous compounds in organic solvents, which can be fine‐tuned by varying the length and number of the (CF2)nsegments in the ponytails. Suitably designed fluorous catalysts can thus be employed under homogeneous conditions at elevated temperatures, and recovered by solid/liquid phase separation at lower temperatures. Fluorous solid supports such as fluoropolymers and fluorous silica gel can be used to aid the recovery of small catalyst quantities, and render phase separation more efficient. The use of CO2pressure as a non‐thermal solubility trigger, and catalyst recovery by solid phase extraction using non‐fluorous solvents, are also detailed.
Chemistry and Applications of Iron–TAMLCatalysts in Green Oxidation Processes Based on Hydrogen Peroxide
Authors: Collins Terrence J. , Khetan Sushil K. , Ryabov Alexander D.
Published: June 2010

Iron–tetraamido macrocyclic ligand (TAML) activators have been designed and developed to provide small‐molecule mimics, the peroxidase enzymes. Fe–TAML activators are proving to be highly active catalysts that function effectively at very low concentrations from nanomolar to low micromolar. Notably, they are capable of performing many thousands of turnovers per minute under ambient conditions, of functioning over a broad pH range from acidic and most notably for iron catalyst to basic and even to highly basic, of presenting a broad range of selectivities and oxidative aggression determined by the conditions of use and the choice of catalyst over the 14 catalysts presented. The catalysts have fulfilled the design criteria and now provide the basis of platform technology for myriad applications. Published kinetics and mechanistic interpretations are reviewed to illustrate the success of the design protocol. Published applications are briefly described. A highly developed field of use involves the use of Fe–TAML–peroxide for the purification of water of persistent pollutants and hardy pathogens.
Immobilization and Compartmentalization of Homogeneous Catalysts
Authors: Müller Christian , Vogt Dieter
Published: June 2010

The sections in this article are

Introduction

Soluble Dendrimer‐bound Homogeneous Catalysts

Covalently Linked Dendrimer‐bound Catalysts

Carbosilane Dendrimers as Soluble Supports

Poly(Benzyl Ether) Dendrimers as Soluble Supports

DABDendrimers as Soluble Supports

PAMAMDendrimers as Soluble Supports

PPIDendrimers as Soluble Supports

Non‐covalently Linked Dendrimer‐bound Catalysts

Polymer‐bound Homogeneous Catalysts

Covalently Linked Polymer‐bound Catalysts

Molecular Weight Enlargement for Continuous Homogeneous Catalysis

Soluble Polymer‐supported Catalysts for Liquid–Liquid Recovery of Catalysts

Electrostatically Bound Catalysts

Conclusion and Outlook
Industrial Applications of Homogeneous Enantioselective Catalysts
Authors: Blaser Hans‐Ulrich , Hoge Garrett , Pugin Benoît , Spindler Felix
Published: June 2010

This chapter describes the state of the art of the application of homogeneous enantioselective catalysts for the industrial production of chiral fine chemicals. Covered are enantioselective catalytic processes that have been and/or are currently used for the commercial manufacture of chiral compounds and also selected pilot‐ and bench‐scale processes not (yet) used in actual production, together with a few selected feasibility studies. After a short introduction, essential requirements and suitable strategies for the application of homogeneous catalysis in fine chemicals production are discussed. In the subsequent sections, enantioselective catalytic processes are described, organized according to the following reactions and substrate types: hydrogenation of dehydro‐α‐ and ‐β‐amino acid derivatives; simple enamides and enol acetates; itaconic acid derivatives; allylic alcohols and α,β‐unsaturated acids; miscellaneous CC systems; α‐ and β‐functionalized ketones; aromatic ketones; CN bonds; oxidation of sulfides; Sharpless epoxidation and dihydroxylation; Jacobsen epoxidation; isomerization; addition reactions to CC, CO and CN bonds; and opening of oxacycles.
Hydrogenation forCCBond Formation
Authors: Bower John F. , Krische Michael J.
Published: June 2010

The sections in this article are

By‐product‐freeCCCoupling and the Departure from Preformed Organometallic Reagents

Hydrogenative Vinylation of Carbonyl Compounds and Imines

Hydrogenative Allylation of Carbonyl Compounds

Hydrogenative Aldol and Mannich Additions

Hydrogenative Acyl Substitution (Reductive Hydroacylation)

Hydrogenative Carbocyclization

Future Directions

Acknowledgments
Palladacycles in Catalysis
Authors: Dupont Jairton , Flores Fabricio R.
Published: June 2010

Palladium compounds containing a Pd‐C that are stabilized intramolecularly by at least one two‐electron donor group have numerous applications as pre‐catalysts. In particular, these compounds denominated palladacycles possess very attractive properties such as high thermal stability and low air sensitivity and they are ease to handle. These compounds are very active catalyst precursors in Heck coupling, Suzuki coupling, Buchwald–Hartwig amination and related coupling reactions under mild conditions, for instance at room temperature or in water. However, palladacycles serve as precursors to highly active palladium(0) species consist of soluble clusters or colloids, often stabilized by quaternary ammonium salts in highly dilute solutions or highly active low‐coordinate complexes of electron‐rich phosphines or carbenes. Moreover, chiral palladacycles are very important catalysts for enantioselective allylic rearrangements, allylic additions and aldol chemistry, since they act as Pd(II) Lewis acids and no redox process occurs
Homogeneous Catalyst Design for the Synthesis of Aliphatic Polycarbonates and Polyesters
Authors: Coates Geoffrey W. , Jeske Ryan C.
Published: June 2010

Aliphatic polyesters and polycarbonates are generally biodegradable materials and as a result they have many important uses in agricultural, medical and packaging applications. This chapter focuses on the use of homogeneous catalysts for the synthesis of these environmentally benign polymers.
Zeolites in Catalysis
Authors: Brown Stephen H.
Published: June 2010

Zeolite catalysts are commonly used tools for the production of fuels and petrochemicals from crude oil and natural gas. The active site in a zeolite catalyst is typically a Brønsted acid. This chapter reviews the mechanisms of acid‐catalyzed reactions of hydrocarbons. When these reactions take place inside the pores of zeolite catalysts, steric constraints influence the product distribution. This is often referred to as shape selectivity. Various types of zeolite shape selectivity are illustrated using important industrial reactions.
Sol–Gel Sulfonic Acid Silicas as Catalysts
Authors: Lee Adam F. , Wilson Karen
Published: June 2010

Silica‐supported sulfonic acids are a class of solid Brønsted acid catalysts that generally comprise organo‐sulfonic acid groups tethered to silica surfaces. Methodologies to prepare organically modified silica have been widely developed in separation science and the techniques for their preparation are well documented. The application of this chemistry to prepare pure Brønsted sulfonic acid functionalized mesoporous silicas has stimulated significant research effort in this area, since these materials are interesting alternatives to commercially available sulfonated polymer resins, such as Amberlyst–15 and Nafion‐H (sulfonated polystyrene and perfluorinated sulfonic acid resins respectively), which suffer from low surface areas and thermal stability. This chapter presents an overview of the preparation of mesostructured silica supported sulfonic acids, their catalytic applications and reviews the approaches taken to tune catalyst performance in organic transformations.
Applications of Environmentally Friendly
Ti
O
2
Photocatalysts in Green Chemistry: Environmental Purification and Clean Energy Production Under Solar Light Irradiation
Authors: Matsuoka Masaya , Anpo Masakazu
Published: June 2010

Recent developments in titanium dioxide‐based photocatalysts are reviewed concerning developments in the highly dispersed TiO
2
photocatalysts prepared on or within zeolites and visible light‐responsive TiO
2
photocatalysts. Special attention is focused on the application of these catalysts in green chemistry, e.g. solar energy conversion and environmental protection. The unique applications of TiO
2
species within zeolites for environmental protection such as reduction of CO
2
and H
2
O and direct decomposition of NO

x

into N
2
and O
2
are discussed, focusing on the relationship between the reactivity and local structures of the TiO
2
species. The preparation of visible light‐responsive TiO
2
photocatalysts by applying ion engineering techniques such as ion implantation and an RF magnetron sputtering deposition method is discussed, with emphasis on its unique reactivity for the separate evolution of H
2
and O
2
from water under sunlight irradiation.
Nanoparticles in Green Catalysis
Authors: Kidwai Mazaahir
Published: June 2010

In recent years, there has been growing interest in the catalytic properties of transition metal nanoparticles. The high surface area‐to‐volume ratio of solid‐supported metal nanoparticles is mainly responsible for their catalytic properties and this can be exploited in many industrially important reactions. Green chemistry and nanotechnology are the tools which can be used simultaneously for the development of the various industrial and biologically active components. Various organic transformations and syntheses were carried out using both methodologies as a synthetic tool, as described in this chapter.
‘Heterogreeneous Chemistry’
Authors: Jacobsen Heiko
Published: June 2010

‘Heterogreeneous Chemistry’ adheres to the philosophy of green chemistry, outlined in the ‘12 Principles of Green Chemistry’, and is intimately linked to heterogeneous catalysis. The concept of ‘Heterogreeneous Chemistry’ is illustrated in catalytic applications relating to uses of renewable feedstocks, in particular biomass. Since solvents play an essential role in green catalysis, ‘heterogreeneous’ aspects of solvents systems are discussed.
Sustainable Heterogeneous Acid Catalysis by Heteropoly Acids
Authors: Kozhevnikov Ivan
Published: June 2010

Heterogeneous acid catalysis byheteropoly acids(HPAs) has the potential for substantial economic and green benefits. The aim of this chapter is to discuss the perspectives of acid catalysis by solid HPAs, focusing in particular on several approaches that could help to achieve sustainable catalyst performance. These approaches include developing novel HPA catalysts possessing high thermal stability, modification of HPA catalysts to enhance coke combustion, inhibition of coke formation on HPA catalysts during operation and reactions in supercritical fluids and cascade reactions using multifunctional HPA catalysis.
The Kinetics ofTiO2‐based Solar Cells Sensitized by Metal Complexes
Authors: Fitch Anthony G. , Walker Don , Lewis Nathan S.
Published: June 2010

The sections in this article are

Introduction

History

DSSCDesign

Function of theDSSC

Performance of aDSSC

Kinetics Processes

Charge Injection

Recombination to the Dye

Regeneration

Conclusion

Acknowledgment
Automotive Emission Control: Past, Present and Future
Authors: Farrauto Robert J. , Hoke Jeffrey
Published: June 2010

The first automobile catalysts, for gasoline fueled internal combustion engines (IC) were introduced in 1975. They were designed to facilitate the reduction of carbon monoxide (CO) and unburned gasoline derived hydrocarbons (HC). The catalyst had to continue to function with an approximate reduction of 90% (relative to an uncontrolled 1970 vehicle) for 50,000 miles. The automobile industry was skeptical since the success of the catalyst was dependent on the driving and maintenance cycles of the average consumer. Since that time we have seen one of the most successful applications of catalysis for cleaning emissions from IC engines including gasoline, diesel, two and 4 cycle engines, power plants, chemical plants, restaurants, and wide body aircraft to name a few. Today we see the three way catalyst (TWC) as the heart of a closed loop engine control strategy successfully reducing emissions of CO, HC and oxides of nitrogen (NO
x
) to near zero for 150,000 miles. This has clearly been an achievement of epic proportions with a positive impact on the environment and the health of the world.

Now catalytic scientists and engineers are faced with new challenges for controlling diesel engine emissions for trucks, buses and passenger cars. As we approach 2010 Federal Standard emissions of CO, HC, NO
x
and particulates must approach zero levels. The homogeneous charge combustion engine (HCCI) is in development and holds promise for cleaner diesel emissions.

This review provides a brief history of some of the accomplishments in controlling emissions from the gasoline and diesel engines. It also describes alternative technologies under investigation including advanced NO
x
reduction, new engine concepts and the fuel cell as the end game in the hydrogen economy. A common thread for all these technologies is heterogeneous catalysis.
Heterogeneous Catalysis for Hydrogen Production
Authors: Scott Morgan S. , Idriss Hicham
Published: June 2010

Hydrogen is poised as one of the main energy carriers in the future, in particular if ways of making it from renewable sources are made available using reliable technologies. This chapter deals with heterogeneous catalytic systems for making hydrogen from ethanol, a biorenewable source. The two main methods for making hydrogen are discussed: oxidation and reforming. The catalytic role is also discussed in terms of its components with emphasis on noble metals deposited over nanoparticles of cerium oxide, one of the most active catalysts for this reaction.
High‐Throughput Screening of Catalyst Libraries for Emissions Control
Authors: Cypes Stephen , Cizeron Joel , Hagemeyer Alfred , Volpe Anthony
Published: June 2010

Catalysis plays a very important role in sustainable and green chemistry applications such as renewable resources for energy and fuels, waste recovery and recycling and low‐ or even zero‐emissions power plants, chemical production sites and vehicles. Emissions control and environmental protection are new challenges that call for novel and far more efficient catalysts to be developed in short time periods. In this chapter, examples of the application of high‐throughput methods to heterogeneously catalyzed green chemistries are discussed. High‐throughput and combinatorial catalysis is ideally suited for the discovery of novel noble metal and mixed metal oxide catalyst formulations for total combustion/volatile organic compound(VOC) removal, emissions control from stationary and mobile sources (NOxabatement, CO oxidation, automotive three‐way catalysis) because simple gas‐phase feeds and product mixes allows for truly parallel detection and very high sample throughputs. Furthermore, these methods are advantageously applicable to multicomponent catalysts (e.g. mixed metal oxides, alloys) for selective oxidation, hydrogenation, dehydrogenation and refining, including desulfurization and denitrification. Additionally, improved fast analytical techniques are making it increasingly possible to perform high‐throughput experimentation on complex real plant or vehicle feeds. This chapter focuses on the primary screening of metal oxides for low‐temperature CO oxidation and VOC combustion using infrared thermography reactors and SCR DeNOxof wafer‐formatted catalyst libraries using scanning mass spectrometry.
Catalytic Conversion of High‐Moisture Biomass to Synthetic Natural Gas in Supercritical Water
Authors: Vogel Frédéric
Published: June 2010

Methane produced from waste biomass is a renewable and clean biofuel that can be distributed using the existing natural gas infrastructure. It can be used for heat and power generation and as a transportation fuel. High‐moisture biomass is a relatively untapped resource with a significant energetic potential and attractive costs. However, new technologies are needed for converting high‐moisture biomass efficiently into methane and recovering the nutrients for use as a fertilizer. Gasification of the biomass in a hydrothermal environment is an emerging technology that offers many advantages over gas‐phase conversion processes or anaerobic digestion. Heterogeneous catalysis is the key to a successful hydrothermal gasification process for the synthesis of methane. Only a few metals, including Ru, Ni, Rh and Pt, are useful under these conditions. Pd and Co catalysts might also be suitable but conclusive data are lacking. Alloying is another approach that holds promise to yield active and stable catalysts. The choice of hydrothermally stable supports is limited to some insoluble oxides and carbon. Some of these oxides have not yet been tested as catalyst supports (e.g. Nb2O5, Ta2O5and UO2) and might prove useful. The mechanism for the gasification of the organic compounds to CO and H2is likely to follow a Mars–van‐Krevelen redox cycle with two oxides of the catalytic metal involved. The strongest evidence for such a mechanism was found for RuO2, but specificin situstudies are needed for corroborating this hypothesis and determining the actual oxidation states involved in the mechanism. Deactivation in hydrothermal gasification follows the same modes as in gas‐phase and liquid‐phase catalysis. Coke deposition is not a primary cause of deactivation due to the high partial pressure of water and the high solubility of coke precursors in near‐ and supercritical water. Salts play a crucial role in catalyst deactivation. Sulfate was found to be a strong poison for Ru catalysts, but the actual poison might be sulfide, formed by reduction of the sulfate with hydrogen or organic compounds. Based on this knowledge, a continuous catalytic hydrothermal gasification process is under development at PSI featuring continuous on‐line salt precipitation and removal before the catalytic reactor.
Catalysis with CytochromeP450 Monooxygenases
Authors: Urlacher Vlada B.
Published: June 2010

Cytochromes P450 belong to the ever‐growing superfamily of heme‐containing monooxygenases with currently more than 7700 gene sequences found in all domains of life. Cytochrome P450 enzymes play a central role in drug metabolism and have been shown to be involved in the biosynthesis of important natural compounds. These enzymes convert a vast range of substrates and catalyze diverse reactions. Their properties have been used for drug development, bioremediation and the synthesis of fine chemicals. Significant progress has been made over the past decade in engineering P450 monooxygenases with widely altered substrate specificities, substantially increased activity and enhanced stability. Furthermore, several approaches for the replacement or regeneration of the cofactor NAD(P)H have been developed, allowing the more cost‐effective use of P450 enzymes. In this chapter, we focus on the recent progress in applying P450 monooxygenases as biocatalysts. The P450 engineering issue will also be discussed.
Biocatalytic Hydrolysis of Nitriles
Authors: Brady Dean
Published: June 2010

The function, uses and commercial applications of nitrile biocatalysts are reviewed. Particular consideration is given to benefits of the technology regarding the impact of nitrile hydrolysis on the environment. The challenges, solutions and opportunities facing the broader application of this technology are also discussed.
Biocatalytic Processes Using Ionic Liquids and Supercritical Carbon Dioxide
Authors: Lozano Pedro , De Diego Teresa , Iborra José L.
Published: June 2010

Biocatalytic processes based on ionic liquids (ILs) and supercritical carbon dioxide are interesting alternatives to organic solvents for designing clean synthetic chemical processes to obtain pure products directly. In such enzymatic processes, the classical advantages of supercritical carbon dioxide to extract, dissolve and transport chemicals are compromised by the denaturing effect that it has on enzymes. On the other hand, ILs have shown themselves to be excellent non‐aqueous environments for enzyme catalysis. Biphasic systems based on ILs and supercritical carbon dioxide have been proposed as the first approach to integral green bioprocesses in non‐aqueous media, where both the biocatalytic and extraction steps are coupled in an environmentally benign and efficient reaction/separation process.
Thiamine‐Based Enzymes for Biotransformations
Authors: Pohl Martina , Gocke Dörte , Müller Michael
Published: June 2010

Chiral and prochiral α‐oxyfunctionalized compounds, in particular carboxylic acids, aldehydes, ketones, alcohols, are indispensable building blocks for asymmetric synthesis. 2‐Hydroxy ketones encompassing a chiral and prochiral center are therefore versatile building blocks for organic synthesis, as they can be easily transformed into other functionalities, such as diols, epoxides, amino alcohols and diamines. The review describes the current state of the art concerning thiamine diphosphate‐dependent enzymes, which catalyze the formation of chiral 2‐hydroxy ketones.
Baeyer–Villiger Monooxygenases in Organic Synthesis
Authors: Kirschner Anett , Bornscheuer Uwe T.
Published: June 2010

The sections in this article are

Introduction

General Aspects of the Baeyer–Villiger Oxidation

Mechanistic Aspects

Chemical Versus Enzymatic Baeyer–Villiger Oxidation

Biochemistry of Baeyer–Villiger Monooxygenases

Catalytic Mechanism

Structural Features

Application of Baeyer–Villiger Monooxygenases in Organic Chemistry

Isolated Enzymes Versus Whole Cells

Baeyer–Villiger Monooxygenases Relevant for Synthetic Applications

Representative Synthetic Applications

Kinetic Resolutions of Racemic Ketones

Desymmetrization of Prochiral Ketones

Regiodivergent Transformations

Large‐Scale Application

Heteroatom Oxidation

Protein Engineering

Conclusions and Perspectives

Acknowledgments
Bioreduction by Microorganisms
Authors: Andrade Leandro Helgueira , Nakamura Kaoru
Published: June 2010

An outline of and recent progress in the enzymatic reduction of carbonyl groups are presented from the viewpoint of green chemistry.
Biotransformations and the Pharma Industry
Authors: Meyer Hans‐Peter , Ghisalba Oreste , Leresche James E.
Published: June 2010

Biotechnology should focus on areas where organic chemists have a true need. This is less in the area of renewable feedstocks than in the area of ecologically burdened synthetic chemical methods, which should be replaced as soon as possible by biotransformation steps. An analysis of the organic chemical toolbox shows the directions in which the efforts in enzyme screening and improvement must go. The still suboptimally equipped enzymatic toolbox must be filled with readily available enzymes that can be used by organic chemists.
PAHBioremediation by Microbial Communities and Enzymatic Activities
Authors: Andreoni Vincenza , Gianfreda Liliana
Published: June 2010

Polycyclic aromatic hydrocarbons (PAHs) are hydrophobic, persistent, ubiquitous pollutants of the environment. The capability for PAH degradation of soil indigenous microorganisms has been investigated in numerous studies. PAH‐degrading bacteria have been found in pristine and contaminated temperate and tropical zone ecosystems, in Arctic and Antarctic soils, in sediments and in the rhizosphere of numerous different plants. A broad range of oxygenases is distributed among the microorganisms growing on PAHs and several groups of genes for the initial PAH oxygenation are now known. Gene sequences encoding for enzymes specific for the initial and ring oxygenase have been used to construct specific probes. The broad biodegradative capabilities evolved by microorganisms towards these compounds and the available tools for monitoring their presence in the environment account for bioremediation‐based strategies with the potential to restore PAH‐contaminated soils. Compost and composting matrices have enormous potential for assisting the bioremediation of PAH‐polluted soils and both techniques have been successfully applied to ameliorate soil contaminated with PAHs. One way to achieve trulyin situbioremediation is by utilizing plants to perform rhizosphere bioremediation. Phytoremediation is of particular interest as a secondary polishing approach for PAH‐contaminated soil previously treated by land farming, augmentation of the soil with selected PAH‐degrading bacteria and growth of plants with plant growth‐promoting rhizobacteria. A different approach, alternative to whole microbial and plant cells, is the use of extracellular enzymes, such as oxidoreductases of fungal origin with known abilities to transform or even to degrade PAHs effectively.
Introduction
Authors: Jessop Philip , Leitner Walter
Published: June 2010

The sections in this article are

What is a Supercritical Fluid (SCF)?

Practical Aspects of Reactions in Supercritical Fluids

The Motivation for Use ofSCFsin Modern Chemical Synthesis

The History and Applications ofSCFs

The Discovery ofSCFsand Their Use as Solvents

Extraction and Chromatography inSCFs

The History of Chemical Reactions inSCFs

Industrial Use ofSCFsas Reaction Media
Basic Physical Properties, Phase Behavior and Solubility
Authors: Foster Neil R. , Lucien Frank P. , Mammucari Raffaella
Published: June 2010

The sections in this article are

Introduction

Basic Physical Properties of Supercritical Fluids

Phase Behavior in High‐Pressure Systems

Types of Binary Phase Diagrams

Asymmetric Binary Mixtures

Factors Affecting Solubility in Supercritical Fluids

The Supercritical Solvent

Chemical Functionality of the Solute

Temperature and Pressure Effects
Expanded Liquid Phases in Catalysis: Gas‐expanded Liquids and Liquid–Supercritical Fluid Biphasic Systems
Authors: Hintermair Ulrich , Leitner Walter , Jessop Philip
Published: June 2010

The sections in this article are

A Practical Classification of Biphasic Systems Consisting of Liquids and Compressed Gases for Multiphase Catalysis

Physical Properties of Expanded Liquid Phases

Volumetric Expansion

Density

Viscosity

Melting Point

Interfacial Tension

Diffusivity

Polarity

Gas Solubility

Chemisorption of Gases in Liquids and their Use for Synthesis and Catalysis

In SituGeneration of Acids and Temporary Protection Strategies

Switchable Solvents and Catalyst Systems

Using Gas‐expanded Liquids for Catalysis

Motivation and Potential Benefits

Sequential Reaction–Separation Processes

Tunable Precipitation and Crystallization

Tunable Phase Separations

Tunable Miscibility

Hydrogenation Reactions

Carbonylation Reactions

Oxidation Reactions

Miscellaneous

Why Perform Liquid–SCFBiphasic Reactions?

By Necessity (Unintentional Immiscibility)

To Facilitate Post‐Reaction Separation

To Facilitate Product/Catalyst Separation in Continuous Flow Systems

To Stabilize a Catalyst

To Remove a Kinetic Product

To Control the Concentration of Reagent or Product in the Reacting Phase

To Permit Emulsion Polymerization

To Create Templated Materials

Biphasic Liquid–SCFSystems

Solvent Selection

Aqueous–SCFBiphasic Systems

Ionic Liquid–SCFBiphasic Systems

Polymer–SCFBiphasic Systems

Liquid Product–SCFBiphasic Systems

Biphasic Reactions in Emulsions

Water‐in‐SCFInverse Emulsions

SCF‐in‐Water Emulsions

Ionic Liquid‐in‐SCFEmulsions

Applications of Emulsions
Synthetic Organic Chemistry in Supercritical Fluids
Authors: Rayner Christopher M. , Rose Paul M. , Barnes Douglas C.
Published: June 2010

The sections in this article are

Introduction

Hydrogenation in Supercritical Fluids

Asymmetric Hydrogenation and Related Reactions

Hydroformylation and Related Reactions in Supercritical Fluids

Oxidation Reactions in Supercritical Fluids

Palladium‐mediated Coupling Reactions in Supercritical Fluids

Miscellaneous Catalytic Reactions in Supercritical Fluids

Metal‐catalyzed Processes

Base‐catalyzed Processes

Acid‐Catalyzed Processes

Cycloaddition Reactions in Supercritical Fluids

Photochemical Reactions in Supercritical Fluids

Radical Reactions in Supercritical Fluids

Biotransformations in Supercritical Fluids

Conclusion

Acknowledgments
Heterogeneous Catalysis
Authors: Gläser Roger
Published: June 2010

The sections in this article are

Introduction and Scope

General Aspects of Heterogeneous Catalysis inSCFsandGXLs

Utilization ofSCFsin Heterogeneous Catalysis

General Considerations

Rate Enhancement

Selectivity Tuning

Lifetime/Stability Enhancement

Reactor and Process Design

Utilization ofGXLsin Heterogeneous Catalysis

Selected Examples of Heterogeneously Catalyzed Conversions inSCFsandGXLs

Conversions inSCFs

Hydrogenations

Fischer–Tropsch Synthesis

Hydroformylations

Oxidations

Alkylations

Isomerizations

Miscellaneous

Conversions inGXLs

Outlook
Enzymatic Catalysis
Authors: Lozano Pedro , De Diego Teresa , Iborra José L.
Published: June 2010

The sections in this article are

Enzymes in Non‐aqueous Environments

Supercritical Fluids for Enzyme Catalysis

Enzymatic Reactions in Supercritical Fluids

Reaction Parameters in Supercritical Biocatalysis

Stabilized Enzymes for Supercritical Biocatalysis

Enzymatic Catalysis inIL–scCO2Biphasic Systems

Future Trends

Acknowledgments
Polymerization in Supercritical Carbon Dioxide
Authors: Beginn Uwe
Published: June 2010

The sections in this article are

General Aspects

Introduction and Scope

Supercritical Fluids

Solubility of Macromolecules inscCO2

Stabilizer Design for Dispersion Polymerizations

Limitations of Polymer Preparation inscCO2

Polymerization inscCO2

Radical Polymerization inscCO2

Side‐chain Fluoropolymers

Fluoroolefin Polymers

Poly(Methyl Methacrylate)

Polystyrene

Other Vinyl Monomers

Metal‐catalyzed Polymerizations

Polyolefins

Other Metal‐catalyzed Polymerizations

Ionic Chain Polymerizations

Cationic Polymerizations

Coordinative Anionic Polymerization

Conclusion
Synthesis of Nanomaterials
Authors: Liu Zhimin , Han Buxing
Published: June 2010

The sections in this article are

Introduction

Metal and Semiconductor Nanocrystals

Direct Synthesis of Nanocrystals in
SCFs

Synthesis in
sc
CO
2

Synthesis in Supercritical Organic Solvents

Synthesis in Supercritical Water (
sc
H

2

O
)

Synthesis of Nanomaterials in
SCF
‐based Microemulsions

Water‐in‐Supercritical Alkane Microemulsion

Water‐in‐
sc
CO

2

Microemulsions

Recovery of Nanoparticles from Reverse Micelles Using
sc
CO
2

Metal Oxide Nanoparticles

Supercritical Hydrothermal Synthesis

Direct Sol–Gel Synthesis in
sc
CO

2

Synthesis Using Water‐in‐
CO

2

Microemulsions

Carbon Nanomaterials

Carbon (
CNTs
) Nanotubes

Carbon Nanocages

Nanocomposites

Synthesis of Polymer‐based Composites

Decoration of Nanoparticles on Carbon Nanotubes

Deposition of Nanoparticles on Porous Supports

Some Other Nanocomposites

Conclusion
Electrochemical Reactions
Authors: Mabrouk Patricia Ann
Published: June 2010

The sections in this article are

Introduction

Electrochemical Methods

Analytes

Electrolytes

Electrochemical Cell and Supercritical Fluid Delivery System

Electrodes

Working Electrode

Reference Electrode

Solvents

Supercritical Carbon Dioxide

Electrode Modification

Hydrophobic Electrolytes

Water‐in‐Carbon Dioxide Microemulsions

Hydrofluorocarbon Supercritical Solvents

Applications

Electrochemical Synthesis in Supercritical Solvents

Electrochemical Detection in Supercritical Solvents

Conclusion and Outlook
Green Acid Catalysis in Water
Authors: Ogawa Chikako , Kobayashi Shū
Published: June 2010

The sections in this article are

Introduction

Lewis Acids in Water

Introduction. Lewis Acids in Aqueous Media: Possible?

Lewis Acid Catalysis in Water as “Sole Solvent”

LASC: Lewis Acid–Surfactant Combined Catalyst

Polymer‐supported Scandium Triflate

Silica Gel‐supported Scandium with Ionic Liquid

Chiral Lewis Acid‐catalyzed Asymmetric Reactions in Water

Mannich‐type Reactions in Water

Michael Reaction in Water

Epoxide Ring‐opening Reaction in Water

Hydroxymethylation in Water

Brønsted Acid Catalysis in Pure Water

Surfactant‐type Brønsted Acid Catalysts

Polymer‐supported Brønsted Acid Catalysts

Conclusion and Perspective