Do It Yourself Solar Energy

DIY 3D Solar Panels

Almost everyone in the United States is currently paying higher electricity bills. This usually eats deep into your salary. Fortunately, switching to solar energy is one way to save money and make your home eco-friendly. In DIY 3D Solar Panel, a pioneer in the field of solar panels known as Zak Bennet will teach you exactly how to set up a 3D Solar Panels in your home within 24 hours. You can be able to do this using tools you can easily find in your garage. He will also show you other tools you need to make this dream of living off-the-grid and saving money on electricity bill come true. This course contains an eBook and video guide. It is very affordable and you can get a refund if you don't like it. Continue reading...

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Molecular Processes Underlying Enthalpy Entropy and Free Energy for Crystallization

Release or binding of water and other small molecules on crystallization (45). With this in mind, we can write an expression for the free energy for crystallization as follows Here, AH - TAS solvent are contributions associated with Q, and AS protein is the loss of entropy of the protein molecules. A crude estimate of AS protein and of the relative weights of the two entropy contributions can be obtained by comparing the standard free-energy change for apoferritin crystallization AG determined from the solubility to the value corresponding to the intermolecular bond free energy Q. To get AH - TAS solvent from Q 3 kBT 7.3 kJ mol, we have to multiply Q by Zl 2 6, the half-number of neighbors in the crystal lattice (two molecules partake in a bond, in an f.c.c. lattice Z1 12) and, accounting for the sign, we get -44 kJ mol. The closeness of AH - TAS solvent to AG indicates the insignificance of AS protein for the free energy of crystallization. The standard free energy of formation of a...

Solar Power for the Masses

So-called thin film photovoltaics are opening the route to low cost electricity. In this context, thin films are 100 nm-100 im thick and made oforganic, inorganic, and organic-inorganic solar cells deposited over rigid or flexible substrates by high-throughput (printing) technologies. If, for example, 35 im ofsilicon were used to manufacture a solar cell instead ofthe state of the art 300 mm- such as in the case of the SilFoil technology based on large area, multijcrystalline silicon foils developed by NanoGram (www. (Figure 1.5) -the cost of silicon-based solar modules would be below 1 W-1. While similar small start- ups eagerly compete to introduce new solar technologies, First Solar already manufactures the equivalent of one large A NEW PARADIGM IN SOLAR ENERGY A NEW PARADIGM IN SOLAR ENERGY nuclear power station, using a deposition technique of inorganic nanocrys-tals of cadmium telluride. Floated on the New York Stock Exchange (NASDAQ) in November 2006 the company's...

Why Nanoscience is Relevant to the Solar Energy Industry

Recently made possible the synthesis of the photoactive layers needed to carry out the photovoltaic conversion with the needed stability required for practical applications. Almost unnoticed among more glamorous scientific disciplines, chemistry in the last 20 years has extended its powerful synthetic methodology to make materials where size and shape are as important as structure. In other words, we have learned how to make nanoscale building blocks of different sizes and shapes, composition, and surface structure such as in the case of the nano ink developed by Nanosolar to make its CIGS panels. For example, the present photovoltaic technologies rely on the quantum nature of light and semiconductors that are fundamentally limited by the band-gap energies. A revolutionary new approach suggested by Bailey in 1972 that revolves around the wave nature of light is now becoming a reality thanks to advances in nanochemistry 11 . The idea is simple to use broadband rectifying (nano)antennas...

Solar Photovoltaic Cell PV

A solar photovoltaic cell (PV) is a device that converts solar energy into electricity in a manner that does not release any pollutants to the environment. Today, solar cells are commonly used to power small-sized items such as calculators and watches. But solar PVs have a great future in providing all the electricity needs for rural communities, homes, and businesses. The future for solar cell production and their usage is very promising as a renewable energy resource. However, the technology still remains expensive when compared to the costs of fossil fuels to produce electricity. is wasted by today's photovoltaic cells. solar cell, they release electrons in the semiconductor to produce an electric current. However, when an electron is set free by the photon, it collides often with a nearby atom making it less likely to set another electron free. So even though the sun's solar photons carry enough energy to release several electrons, producing more electricity, they are limited to...

Solar Energy Photovoltaic Cells

Scientists have been doing a lot of research and experiments with quantum dots to make photovoltaic cells more efficient. Anew quantum-dot-based solar cell has recently been prototyped with 30 percent efficiency. The technology of producing thin-film solar cells has the potential to achieve mass production at low costs. One economic researcher estimates that the market for thin-film solar cells will increase in the next fewyears, and then reach 1.5 billion in sales in 2012. See Chapter 8 for more information about photovoltaic cells.

Ceramic Nanofibers For Clean Energy Sources Excitonic Solar Cells

One of the major challenges that future generations will face is to find out solutions for the increasing energy needs. This challenge stems from the limitations in the stock of natural fossil fuels. Therefore, search for alternate energy source that are not only renewable but also clcan from environmental and other hazards has been initiated worldwide. Photovoltaics (PV) are a promising technology that directly takes advantage of our planet's ultimate source of power - the sun. When exposed to light, solar cells are capable of producing electricity without any harmful effect to the environment or device, which means they can generate power for many years while requiring only minimal maintenance and operational costs. Existing types of solar cells may be divided into two distinct classes conventional solar cells, such as silicon and 1II-V p-n junctions, and excitonic solar cells, ESCs. Most organic-based solar cells, including dye-sensitized solar cells (DSSCs) fall into the category...

Nanotechnology for Photovoltaic Solar Cells and 3D Lithium Ion Microbatteries for MEMS Devices

NT can play a critical role in the design and development of photovoltaic (PV) cells, semiconductor solar cells 5 , and 3-D lithium ion microbatteries (MBs) for integration in MEMS devices or sensors. Solar cells 6 using NT-based ZnO nanorods can provide an electrical power system for battery charging banks that support 12 V lighting and appliances, whereas a 3-D lithium ion battery power package can provide electrical power for automobiles, trucks, emergency lighting for homes in case of power failure or power blackouts cellular and mobile phones, laptops, computers, portable electrical appliances, and host of other electrical appliances. Large solar installation can be tied to an electrical grid system via a grid-tie inverter. A grid-tie system consists of mounting structure, safety disconnects, installation wiring, solar modules comprising of solar cells and a grid-tie inverter. Inverters integrate three functions converting the dc from the solar modules to ac and synchronizing it...

Correlation Of Blockade Duration With Free Energy Of Duplex Stabilization

In the experiments described, the standard free energy of hairpin formation was calculated and compared with the median duration of hairpin shoulder blockades 22 . The median blockade duration correlated remarkably well with the free energy of formation. This correlation would not be expected if the force generated by the electric field was simply unzipping the hydrogen bonded base pairs of the hairpin and drawing the molecule through the pore. Instead the hairpin remains in the vestibule until all of the hydrogen bonded complementary bases dissociate simultaneously, at which point the unwound DNA strand is drawn through the pore to produce the spike. The time required before the hairpin dissociates (the shoulder) is an exponential function of the number of base pairs in the hairpin structure and is directly related to the calculated free energy that stabilizes the hairpin. Note that this relation between free energy and blockade duration also extends to a single nucleotide mismatch...

Engines Of Creation

Some seminal works stand out like beacons in the history of science. Newton's Philosophiae Naturalis Principia Mathematica and Watson and Crick's A Structure for Deoxyribose Nucleic Acid come quickly to mind. In recent decades we can add Eric Drexler's Engines of Creation, which established the revolutionary new field of nanotechnology. In the twenty years since this seminal work was published, its premises and analyses have been confirmed and we are starting to apply precise molecular assembly to a wide variety of early applications from blood cell sized devices that can target cancer cells to a new generation of efficient solar panels. We can now see clearly the roadmap over the next couple of decades to the full realization of Drexler's concept of the inexpensive assembly of macroobjects constructed at the nanoscale controlled by massively parallel information processes, the fulfillment of which will enable us to solve problems energy, environmental degradation, poverty, and...

Moores Law and the SIA Roadmap

These predictions are not restricted to nanoelectronics alone but can also be valid for materials, methods, and systems. There are schools and institutions which are engaged in predictions of how nanotechnology will influence or even rule our lives 2 . Scenarios about acquisition of solar energy, a cure for cancer, soil detoxification, extraterrestrial contact, and genetic technology are introduced. It should be considered, though, that the basic knowledge of this second method of prediction is very limited.

Improvement of Conversion Efficiency

The Third Generation of Solar Power Harnessing - Application of Quantum Dots The DSSC has a theoretical limit of conversion efficiency 31 , which could be shifted 42 if the dyes are replaced by inorganic quantum dots due to the ability of the latter to produce more excitons from a single photon of sufficient energy1'. This phenomenon is called multi-exciton generation (MKG) or impact ionization and has been demonstrated in quantum dots popular semiconductors such as CdSe and PbSc17 38 TO. If this property could be exploited to build solar cclls, then more fraction of the solar energy could be converted into electrical energy. Colloidal CdS quantum dots were used in DSSC as early as 1990, i.e., within two years from the realization of quantum dots, that gave an energy conversion efficiency 6 4 . However this result could not be reproduced and subsequent reports till to date gave efficiencies less than by a factor over two (Table 1). In other words, the performance of quantum dot...

Iron Ruthenium and Osmium

It would be invidious to pick any particular area of activity in the chemistry of these elements for particular attention, but very significant advances have been made in many aspects of the coordination chemistry of iron, ruthenium, and osmium. Our understanding of the roles which iron can play in biological systems and the subtle chemical control over iron metabolism has increased enormously since 1987 and they represent beautiful aspects of applied coordination chemistry. Much iron coordination chemistry is designed to further understand biomimetic aspects. In low-oxidation-state ruthenium chemistry, renewed interest in photovoltaic cells is generating a resurgence in Ru(bpy)3 chemistry. In high-oxidation-state ruthenium and osmium chemistry, the utilization of complexes as increasingly selective catalytic or stoichiometric oxidizing agents shows no sign of abating.

Solar Furnace Results

In order to proceed to a large-scale synthesis of single-wall carbon nanotubes, which is still a challenge for chemical engineers, Flamant et al. 3.56 recently demonstrated that solar energy-based synthesis is a versatile method to obtain SWNTs and can be scaled from 0.1-0.5 g h to 10 g h and then to 100 g h productivity using existing solar furnaces. Experiments at medium scale (10-g h, 50 kW solar power) have proven the feasibility of designing and building such a reactor and of the scaling-up method. Numerical simulation was meanwhile performed in order to improve the selectivity of the synthesis, in particular by controlling the carbon vapor cooling rate.

Hard Nanocrystalline Materials

Case of the alloying or a prealloyed material in that of the grinding) of a large amount of mechanical energy that results in a large increase of their free energy (linked both to large deformations and to a high degree of intermixing). From that high-energy state, the material can decay (either spontaneously or after a low temperature treatment) to lower energy configurations, as those corresponding to an extended solid-state solution, metastable phases, and stable phases. Mechanical alloy has been widely used to produce NdFeB and, to a lower extent, SmCo. It is an inexpensive technique, resulting in a powdered material having typical grain sizes of the order of 10 nm that allows to process large amounts of materials and whose only drawback is the impossibility of producing highly textured magnets.

Other Synthesis Methods

Gates et al. have demonstrated a solution-phase synthesis of nanowires with controllable diameters 4.57, 97 , without the use of templates, catalysts, or surfactants. They make use of the anisotropy of the crystal structure of trigonal selenium and tellurium, which can be viewed as rows of 1-D helical atomic chains. They base their approach on the mass transfer of atoms during an aging step from a high free-energy solid phase (e.g., amorphous selenium) to a seed (e.g., trigonal selenium nanocrystal) that grows preferentially along one crystal-lographic axis. The lateral dimension of the seed, which dictates the diameter of the nanowire, can be controlled

Electrodeposition of Nanostructured Materials

Electrodeposition is one of the first chemical (or rather electrochemical) methods for the formation of inorganic coatings on solid surfaces. The formation of metal coatings on the anode by means of electrolysis of respective metal salts has been known since the nineteenth century. During the last few decades, this method has spread to other materials, such as II-VI and II-V semiconductor materials, with the main application in photovoltaic devices and solar cells.

Preparation Of Hydrogenated Nanocrystalline Silicon

Low-temperature fabrication process can be required for thin-film transistors and photovoltaic cells with inexpensive substrates. The following preparation techniques have been used to achieve it (i) plasma-enhanced chemical vapor deposition (PECVD) of silane (SiH4) gas diluted in H2 gas, (ii) thermocatalytic or hot-wire assisted chemical vapor deposition (HWCVD) of SiH4 gas diluted in H2 gas, and (iii) pulsed laser crystallization (PLC) of amorphous silicon films. These techniques are summarized below.

What Limits the Rate of Incorporation of a Molecule in a Kink 71 Diffusion Limited or Transition State Kinetics

The kinetics of chemical reactions in solutions are either limited only by the rate of diffusion of the species (73) or additionally slowed down by a high-energy transition state (74). The former kinetics pathway does not exclude the presence of potential free-energy barriers. It has been shown that if molecules have to overcome a repulsive maximum to reach the bonding minimum, the rate of binding can be evaluated as diffusion over the barrier. The resulting kinetic law contains an exponential dependence on the height of the barrier (74).

Imaging of Molecular Structures in Self Assembled Monolayers

Formation of SAM alkanethiols on surfaces has been a subject of several studies 55, 56 . These studies show that during the formation of alkanethiol SAMs, the head groups adsorb on the surface quickly to minimize their free energy. These molecules are initially in a noncrystalline state called the lying-down state. Over time the molecules pack more closely to form a crystalline state called the standing-up state. The ratio of the two structural states on the gold surface depends on the time that the gold surface is exposed to the solution containing C18SH molecules during sample preparation.

Experimental Facts for Growth Models

Years of study on the growth of catalyst-grown carbon fibers suggested that growth occurs via precipitation of dissolved carbon from a moving catalytic particle surface 8 . Growth terminates when the catalyst particle gets poisoned by impurities or after the formation of a stable metal carbide. The reason put forward for the tubular nature of carbon fibers is that it is energetically favorable for the newly-formed surface of the growing fiber to precipitate as low-energy basal planes of graphite rather than as high-energy prismatic planes. However, the curving of the graphite layers introduces an extra elastic term into the free-energy equation of nucleation and growth, leading to a lower limit ( 10nm) to the diameters of carbon fibers that can form from curved graphite layers 9 . This implies that to explain the growth of carbon nanotubes, where diameters can be much smaller than this threshold value, new mechanisms have to be considered. There are, however, some notable differences...

Physical and Chemical Self Assembly

The central theme behind the self-assembly process is spontaneous (physical) or chemical aggregation of colloidal nano-particles 5.88 . Spontaneous self-assembly exploits the tendency of mono-dispersed nano- or submicro colloidal spheres to organize into a face-centered cubic (FCC) lattice. The force driving this process is the desire of the system to achieve a thermodynami-cally stable state (minimum free energy). In addition to spontaneous thermal self-assembly, gravitational, con-vective, and electrohydrodynamic forces can also be used to induce aggregation into complex 3-D structures. Chemical self-assembly requires the attachment of a single molecular organic layer (self-assembled monolayer, or SAM) to the colloidal particles (organic or inorganic) and subsequent self-assembly of these components into a complex structure using molecular recognition and binding.

GIN Waterhouse1 and H Idriss23

Light from the sun is by far the most abundant source of energy on earth. Yet, at present, less than 0.05 of the total power (15 000 GW annual) used by humans is generated from the sun (excluding solar heating, which contributes around 0.6 ). The estimated practical and convertible power that the earth surface receives is equivalent to that provided by 600 000 nuclear reactors (one nuclear power plant generates, on average, 1 GW power) or about 40 times the present global need.1 One mode of solar energy utilization is the use of sunlight to generate energy carriers, such as hydrogen, from renewable sources (e.g., ethanol and water) using semiconductor photocatalysts.

Never Trust the Skeptics

Solar power currently provides only a very small fraction of global electric power generation, about 12 GW of installed capacity globally, as of 2009, but newly installed capacity is growing at approximately 30 per year and is accelerating. Concentrated solar power (CSP) has already been identified as a clean technology that can satisfy the world ' s rapidly growing energy demand.1* Accordingly, investments are finally flowing and the first CSP plants, such as that in the Spain' s city of Seville (Figure 1.1) serving 6000 families, are starting operation. In Europe, France's President Sarkozy and Germany's Chancellor Merkel seem to have understood the situation. In establishing the new Union for the Mediterranean (Figure 1.2) they and all other government leaders of the member States have agreed to explore feasibility of large-scale generation of solar electricity in North Africa to supply Europe and Middle East countries through solar thermal technologies. Meanwhile, the often...

Transport and Storage

The other critical innovation needed is massive electrical power transmission over continental distances, permitting, for example, hundreds of gigawatts of electrical power to be transported from solar farms in New Mexico to markets in New England. Then all primary power producers can compete, with little concern for the actual distance to market. Clean coal plants in Wyoming, stranded gas in Alaska, wind farms in North Dakota, hydroelectric power from northern British Columbia, biomass energy from Mississippi, nuclear power from Hanford, Washington, and solar power from the vast western deserts. Remote power plants from all over the continent contribute power to consumers thousands of miles away on the grid. Nanotechnology in the form of singlewalled carbon nanotubes (aka buckytubes ), forming what we call the Armchair Quantum Wire, may play a big role in this new electrical transmission system.

Polymer Based Nanosponges

In the hope of making solar energy more useful and affordable, several scientists have been working on creating organic photovoltaic cells. Their goal is to replace the usual silicon (S) with readily available materials such as carbon (C). If they succeed, designers could one day integrate solar cells into everyday gadgets like iPods and cell phones. Even the energy absorbed by window tinting could be used to power a laptop, for example. One team of researchers at the University of California have developed an organic photovoltaic cell that uses a polymer, or plastic, material in a unique way. Like other organic solar cells, the plastic material in their prototype includes a polymer material. The material, composed of common chemicals, is sandwiched between conductive electrodes. Photons in the sunlight knock electrons from the polymer onto one of the electrodes. This causes an electrical imbalance where one electrode becomes positively charged while the other is negatively charged....

Forces Induced By Colloidal Phenomena

Since atoms or molecules at surfaces are always less stable than those in the bulk, surfaces of liquids (and solids) that are interfaced with gases (or vapors) have a natural tendency to get their surface area minimized by minimizing the number of atoms or molecules at the surfaces. Surface tension (y) is a force that operates along the surface as a result of this tendency. This yields the common notion that there can be no such term as surface tension of what. It should be always stated as surface tension of what with which interface. Surface tension is always perpendicular to the surfaces. Thus, its unit is expressed as force unit length. From the viewpoint of energy, this is work (or surface free energy) that is required to increase a given surface by unit area. Thus, it can be stated as energy area as well. In the example of water interfaced with air, y is 72.8 dyne cm (or mN m) or 72.8 mJ m2 (or erg cm2) at 20.0 C.

Selfassembled Fullerene Architectures

More recently, Schuster and coworkers202 have successfully used this metal-templated strategy to build similar structures containing fullerenes as stoppers but including a porphyrin unit into the macrocycle. The fullerenes were functionalized using the Bingel reaction. These systems containing porphyrins are used to transmit and process solar energy into other energy sources. This topic will be analyzed in depth in forthcoming sections.

Photochemical Coenzyme Regeneration in Sol Gel Matrices

The enzyme isocitrate dehydrogenase (ICDH) was used as a model dehydrogenase in this research because the Gibbs free energy of the ICDH reaction strongly favors the oxidation of isocitrate, thereby reducing experimental complications from back reactions (26). ICDH catalyzes the oxidation of isocitrate to a-ketoglutarate using NADP+ as the electron acceptor (Eq. 7)

Nanoparticles Nanocomposites

The above cited works are a few examples to show how the size, shape and spatial distribution of nanoparticles can be characterized by XRD. When the nanoparticles are used to prepare nanocomposites with organic materials, such as polymers, the same methods can be applied. The main difficulties encountered in the dispersion of nanoparticles in polymers are phase separation and agglomeration. Reducing these effects is of utmost importance to enhance the efficiency of fullerene polymer photovoltaic devices or to control the polymer viscosity by nanoparticles addition. In-situ growth of the nanoparticles inside a polymer matrix is an alternative way to control their dispersion.

Intelligent Polymer Networks

Hydrogels can be classified as neutral, anionic or cationic networks. In Table 6.1, some representative functional monomers and their relevant properties are listed for reference. The network swelling behavior is governed by a delicate balance between the thermody-namic polymer-water Gibbs free energy of mixing and the Gibbs free energy associated with the elastic nature of the polymer network. In ionic hydrogels, the swelling is governed by the thermodynamic mixing, elastic-retractive forces, and also by the ionic interactions between charged polymer chains and free ions. The overall swelling behavior and the associated response or recognition are affected by the osmotic force that develops as the

Moth Eyes Inspire Selfcleaning Antireflection Coatings

Min is a student in Peng Jiang's group in the Department of Chemical Engineering at the University of Florida. He explains that commercial silicon nitride ARCs are typically designed to suppress reflection efficiently at wavelengths around 600 nm. ''The reflective loss is rapidly increased for near-infrared and other visible wavelengths, which contain a large portion of the incident solar energy,'' he says. ''In contrast, our subwavelength-structured moth-eye ARCs directly patterned in the substrates are broadband and intrinsically more stable and durable than multilayer ARCs since no foreign material is involved.''

Polymer Microelectronics

Since the 1950s, inorganic silicon and gallium arsenide semiconductors, silicon dioxide, silicon nitride, and metals such as aluminum and copper have been the backbone of the semiconductor industry. However, since the late 1980s, there has been a growing interest in polymer or organic microelectronics based on the conjugated polymers, oligomers, or other molecules. By recent research efforts through novel synthesis and process techniques, the performance as well as the stability and ability to process these active materials has been greatly improved. Although polymer microelectronic devices cannot rival the traditional, mainstream inorganic microelectronic devices due to the relatively low mobilities of the organic semiconductive materials, they can be competitive for the applications requiring structural flexibility, low temperature processing, large-area coverage on materials such as plastic and paper, batch production, and especially low cost. The applications of the polymer...

Related Molecular Structures

Entropy-Driven Molecules Hanke and Metzler 36 have proposed a new type of mechanical molecule based on systems of similar topological nature to rotaxanes and catenanes. Typically, in molecules including rotaxanes and catenanes the Gibbs free energy, F, is minimized by variations in U, the internal energy. The proposed molecules rely on the minimization of the Gibbs free energy by variations in the entropy, S, while the energies and chemical bonds (internal energy U) are left unchanged. The entropy functional units can be specifically controlled by external parameters such as temperature, light, or electromagnetic fields. Functional behavior such as controlled transition from linear chain to ring polymer, swelling de-swelling, switching, and molecular motion could be achieved. One such example provided describes a polymer ring along which a number of slip links are placed. Within each of the fringe loops, additional sliding rings are placed. If the sliding rings are immobile, the...

Hydrogen Fuel Cells and Nanotubes

There is a global effort today to develop renewable energy sources. A great deal of research is being devoted to the production of hydrogen fuel cells. A fuel cell is an electrochemical energy-conversion device. Most fuel cells in use today use hydrogen and oxygen as the chemicals. When oxygen and hydrogen react in a fuel cell electricity is produced and water is formed as a by-product.

Conducting Organic Polymers Within Hybrid Nanocomposite Materials

Notwithstanding their many remarkable properties, the prominence of conducting organic polymers (COPs) has been related to two crucial historical events first, the discovery of their electrical conductivity in 1977 by Shirakawa et al. 12 and later the finding of their electroluminescence in 1990 13 . Their conductivity and functionality can be controlled by means of two characteristic mechanisms redox doping and acid-base doping, allowing for the incorporation of charge-balancing doping counterions. A careful choice of the latter has a direct influence on the final properties such as redox activity and electrochemical properties, catalytic activity, gas sensor capability or processability, among others, and represents a simple way to design tailor-made materials. Obviously, this leads to whole new possibilities for their applications, like conductive plastics, catalysts, membranes, batteries, sensors, etc. On the other hand, under their undoped form COPs behave as intrinsic...

Forces Energies and Kinetic Rates

Anibody-antigen interactions are of key importance for the function of the immune system. Their affinities are known to vary over orders of magnitudes. For single-molecule recognition AFM studies, the molecules were surface-coupled via flexible and distensible crosslinkers 16.4, 10, 13, 14 to provide them with sufficient motional freedom, so that problems of misorientation and steric hindrance that can obscure specific recognition are avoided. In 16.4,12 , the tips were functionalized with a low antibody density, so that on the average only a single antibody on the tip end could access the antigens on the surface. Hence, isolated single molecular antibody-antigen complexes could be examined. It was observed that the interaction sites of the two Fab fragments of the antibody (the antibody consists of two antigen-active Fab-fragments and one Fc-portion) are able to bind simultaneously and independently with equal binding probability. Single antibody-antigen binding events were also...

Nailing Superlyophobic Surfaces

When raindrops splash against your window you probably just think the weather has turned bad again. Physicists and material engineers, on the other hand, are quite fascinated by this process of 'wetting.' What happens when a fluid is brought in contact with a solid surface is much more complex than you might guess from just looking at your wet window. In physical terms, the process of wetting is driven by the minimum free energy principle the liquid tends to wet the solid because this decreases the free energy of the system (in this case the system consists of a liquid plus solid). For low-surface-tension liquids the minimum free energy is achieved only when the liquid completely wets the solid. Understanding these mechanics, and using nanotechnology to structure surfaces to control wetting, has a far-reaching impact for many objects and products in our daily lives by preventing wear on engine parts or fabricating more comfortable contact lenses, better prosthetics, and self-cleaning...

Nanocomposites of Carbon Nanotubes and Conducting Polymer

The synthesis of carbon nanotube polymer composites is a promising approach to the effective incorporation of carbon nanotubes (CNs) into practical devices 49 1 The combination of the unique properties of CNs with conducting organic polymers makes these materials interesting multifunctional systems with great potential in many applications not only as supercapacitors, but also in sensors, advanced transistors, high-resolution printable conductors, electromagnetic absorbers, photovoltaic cells, photodiodes and optical limiting devices 1 13 1 As a result of their optical limiting performance and good photoconductivity, special attention has been given to CNs functionalized with poly (N-vinyl carbazole)(PVK) 23, 50-53 . Two methods of synthesis of PVK CNs composites have been reported direct mixing of the polymer with CNs, and chemical polymerization of monomer in the presence of carbon nanoparticles 53, 54 . When preparing a composite, it is essential to determine the type of...

Electromagnetic Sensors

To develop a nanoscale photosensor, it is possible to ride on the back of research in solar power generation. In Chapter 5, we discussed the development of the photoelectrochemical cells, such as those developed by Michael Graetzel for capturing sunlight. These cells use molecular dyes that are excited by capturing sunlight. The excited molecules then transfer an electron into a nanoscale quantum dot of a semiconductor like titanium dioxide. Using one of these photoelectric devices as a sensor is straightforward. It is simply necessary to measure that the electron has been transferred, and this is relatively easy to do because the transferred electron moves through an external circuit to lower its energy by recombining with the positive charge left behind on the dye. In other words, if a photocell is producing electricity, we know that it has been exposed to light.

Hybrid Solar Cells with Inorganic Semiconductors

The group of Alivisatos developed in 2002 64 hybrid solar cells making use of inorganic semiconductor nanoparticles. This type of device, called hybrid nanocrys-tal-polymer solar cell(HNSC) was initially made of blends of a conducting organic polymer, poly-3(hexylthiophene), and nanorods of an inorganic semiconductor, CdSe. The authors reported an initial 1.7 efficiency 64 . Examples of crystalline inorganic semiconductors applied in HSC are CuInS2 102-105 , CuInSe2 and CuInTe2 105 , PbS 67, 106-109 , GaAs 68, 110 , PbSe 111 or HgTe nanocrystals 65 . Table 7.2 shows some examples of HSC applying inorganic semiconductor nano-crystal polymer bulk-heterojunctions and their photovoltaic properties. by the nanocrystal-nanocrystal hopping 112 . Thus, reducing the hopping effects will improve transport efficiency. This has been demonstrated by increasing the length of the inorganic nanorods from 7 nm to 30 nm and to 60 nm within the blend. Improvement in EQE when increasing nanorod lengths...

Energy generation and storage

The efficiency of energy conversion of solar energy into electric current can be increased significantly by application of nanomaterials. Beyond that, anti-reflecting coatings for solar cells and collectors can increase the the most efficient sys light conversion efficiency. For applications in space however, clearly tems at present higher demands on solar cells must be fulfilled rather than for terrestrial applications. While due to the mass restrictions in space transportation a maximum efficiency is aimed at, even if expensive manufacturing processes and materials are to be accepted, an appropriate durability of the collectors under space conditions must also be ensured (radiation and corrosion resistance). At present the most efficient solar cells for space applications are based on III V-semi conductors such as GaAs and InP. These cells are manufactured by heteroepitactical deposition on semiconductor substrates. By vertical alignment of two or more compounds In Germany the...

Applications of Nanocrystalline Silicon

At present, a certain type of solar cell is attracting international attention in the area of the photovoltaic, i.e., the so-called heterojunction solar cell. In its simplest form, it is composed of a monocrystalline silicon substrate and an amorphous emitter deposited upon it. High absorption and stability of the amorphous layer as well as the quality of its interface to both the substrate and the antireflection coating still prevent mass production. Therefore, the amorphous layer is replaced by a nanocrystalline layer. The typical structure of such a solar cell is depicted in Fig. 6.2.

Hybrid Solar Cells Processability and Large Scale Fabrication

As shown from the latter example, many encouraging advantages were obtained thanks to the processability offered by COPs and thus, the low-cost manufacturing-when applying solution processing of film-forming polymers. The possibility to replace inorganic photovoltaic devices produced at high cost by solar cells made on thin plastic substrates via printing techniques is an attractive alternative. Assuming that a significant cost reduction can be achieved, a device and module efficiency of 10 and 5 respectively, would be critical to enter the market. The technology, however, must achieve simultaneously three basic requirements in order to reach commercialization high efficiency, long lifetime and low cost per Wp1 166 . Although the three requirements are difficult to achieve, the fabrication of large-area photovoltaic devices ( 2 x 2 cm2 cell unit) by printing techniques is already a reality.

Hybrid polymer Solar Cells

The high absorption coefficients ( 107 m) found in conjugated polymers like poly(p-phenylene vinylene) (PPV) make them viable candidates to use in a combination with n-type semiconducting inorganic materials, which will lead to a simple and effective solar cell. In contrast to inorganic semiconductors, photoexcitation of organic semiconductors generally results in a strongly bound electron-hole pair, called an exciton 13, 14 . In organic semiconductors these excitons are only effectively separated at an interface between a p-type (electron donating) and n-type (electron accepting) material. Hence, in polymer photovoltaic devices, the primary step after absorption of a photon is a photoinduced electron transfer between donor and acceptor type semiconducting materials, yielding a charge-separated state. This photoinduced electron transfer between donor and acceptor boosts the photogeneration of free charge carriers compared to the individual, pure materials. In general, the exciton...

Solvation and Structural Forces

The short-range oscillatory force law is related to the density distribution function and potential of mean force characteristic of intermolecular interactions in liquids. These forces arise from the confining effects two surfaces have on liquid molecules, forcing them to order into quasi-discrete layers. Such layers are energetically or entropically favored and correspond to the minima in the free energy, whereas fractional layers are disfavored (energy maxima). This effect is quite general and arises in all simple liquids when they are confined between two smooth, rigid surfaces, both flat and curved. Oscillatory forces do not require any attractive liquid-liquid or liquid-wall interaction, only two hard walls confining molecules whose shape is not too irregular and that are free to exchange with molecules in a bulk liquid reservoir. In the absence of any attractive pressure between the molecules, the bulk liquid density could be maintained by an external hydrostatic pressure - in...

Healing And Protecting The Earth

With replicating assemblers, we will even be able to remove the billions of tons of carbon dioxide that our fuel-burning civilization has dumped into the atmosphere. Climatologists project that climbing carbon dioxide levels, by trapping solar energy, will partially melt the polar caps, raising sea levels and flooding coasts sometime in the middle of the next century. Replicating assemblers, though, will make solar power cheap enough to eliminate the need for fossil fuels 7 . Like trees, solar-powered nanomachines will be able to extract carbon dioxide from the air 8 and split off the oxygen. Unlike trees, they will be able to grow deep storage roots and place carbon back in the coal seams and oil fields from which it came.

Biomems For Cellular Detection

Mechanical detection of biochemical entities and reactions has more recently been realized through the use of micro and nano-scale cantilever sensors on a chip. As shown in Fig. 9.7(a), these cantilever sensors (diving board type structures) can be used in two modes, namely stress sensing and mass sensing. In stress sensing mode one side of the cantilever is usually coated with a Self-Assembled Monolayer (SAM) of biomolecules that bind to the analyte being detected. The binding of the analyte to the SAM produces a change in surface free energy, resulting in a change in surface stress, which in turn leads to a measurable bending of the cantilever. The bending can then be measured using optical means (laser reflection from the cantilever surface into a quad position detector, like in an Atomic Force Microscope) or electrical means (piezo-resistors incorporated near the fixed edge of the cantilever). To increase the stress sensitivity of the cantilever, the spring constant should be...

Solid Solubility In The FeCu SYSTEM

From X-ray diffraction measurements of Fe100-x Cux samples in the final stage 19, 21-23, 26, 39 it is found that for x 40 the bcc peaks disappear completely and only fcc peaks remain. When x 20, only bcc peaks remain and the solutions have the bcc structure. For 20 x 40, both fcc and bcc diffraction lines coexist even after extended milling. These findings have been confirmed by TEM investigations 25 . The obtained values of lattice constant for the Fe-Cu alloys agree well with data reported in these alloys prepared by evaporation techniques 87, 88 . A schematic illustration of the solid solutions prepared by various techniques in the Fe-Cu system is shown in Figure 6. It is clear that the single fcc phase field is extended significantly by mechanical alloying. The observed fcc-bcc transition can be predicted by the calculated free energy curves determined by the CALPHAD method 48, 55, 68 . When x 40, the free energy of mixing for the fcc structure is smaller than that for

Junctions of Doped Polymers with Inorganic Semiconductors

Hybrid organic-inorganic thin film photovoltaic junctions between conducting polymer and various inorganic semiconductors have been studied by various authors following the first report by Horowitz and Garnier on the combination of monocrystalline n-GaAs and poly(3-methylthiophene) (P3MT) as the p-type conjugated polymer. P3MT was electrochemically grown on n-GaAs and initially obtained in a doped state, but then undoped at negative potentials. Compared to a classical Schottky GaAs Au cell (Jsc 10 mA cm2, Voc 0.42 V, FF 0.67, h 2.8 ) the GaAs P3MT(25 nm) Au cell gave a lower current but higher voltage (Jsc 8.4 mA cm2, Voc 0.7 V, FF 0.64, h 3.5 ) 156, 157 . The role played by theP3MT layer could not be clearly identified it may be acting as a real p-type semiconductor (i.e., p-n heterojunction) or instead as an insulator or a passivation layer (i.e., a metal-insulator-semiconductor (MIS) structure) 158 . improved photovoltaic characteristics of the n-CdS conductive polymer contact was...

Role of Molecular Shape and Surface Structure in Friction

Recent computer simulations 18.274,304,305 of the structure, interaction forces, and tribological behavior of chain molecules between two shearing surfaces indicate that both linear and singly or doubly branched chain molecules order between two flat surfaces by aligning into discrete layers parallel to the surfaces. However, in the case of the weakly branched molecules, the expected oscillatory forces do not appear because of a complex cancellation of entropic and enthalpic contributions to the interaction free energy, which results in

Biological Inspiration and Current Uses

Any discussion of porphyrins must acknowledge that the initial inspiration for research in the field arises from the diverse functions of these molecules in various biological processes. Photosynthesis is the source of most of the free energy that makes life on earth possible both in terms of stored energy and in the production of dioxygen. Porphyrins 1 are the chief arbitrator of solar energy in photosynthesis therefore life depends on these molecules. A variety of diverse organisms exploit porphyrins in extraordinarily different ways because of their stability, their photo- and electrochemical properties, and the ability to fine-tune these functions by modifications of either the tetrapyrrole macrocycle or environmental factors. These functions include (1) chlorophylls are used in the collection and conversion of solar energy into chemical potential in photosynthesis 6 , Porphyrins also form the basis of many commercial products that serve, among other things, as catalysts, sensors,...

Differential Scanning Calorimetry

Typical DSC profiles are shown in Figure 8.3a. These curves clearly show that their unfolding is monophasic (Hairpin), triphasic (Hammer), and biphasic (Pseudoknot), consistent with the observations of the UV melting curves. The resulting thermodynamic profiles for all transitions observed in the folding of each oligonucleotide are listed in Table 8.2. The thermodynamic parameters of each transition show that the favorable free energy contribution results from the characteristic compensation of a favorable enthalpy contribution with an unfavorable entropy contribution. Favorable heat contributions

Mechanical Properties of Phospholipid Membranes

The total surface free energy F of a fluid-state membrane is a linear combination of the elastic relations representing bending and stretching integrated over the entire membrane surface A parameter that strongly affects the surface free energy of membrane structures is adhesion to surfaces. Adhesive behavior is promoted by the attractive potential between the membrane and the surface and is balanced by the elastic energy of the membrane (Seifert and Lipowsky 1990). In the case of an immobilized vesicle, contributes to Equation (9.1) as the effective contact potential and A* is the contact area of the adhered part of the membrane. In addition to the vesicular compartments, lipid nanotubes with a diameter of 100 nm range are the other important constituent of NVNs. Lipid nanotubes form when a point load is applied to a vesicle (Heinrich et al. 1999), involving first-order shape transitions, where the obtained shape represents a minimum in surface free energy that is, the...

Overview of Theoretical Models

We will merely attempt to present a flavor of the area and briefly discuss some simple, general models. Attempts to explain the basic experimental features using the Landau-Devonshire phenomenological theory have been reasonably successful. For a finite-sized, inhomogeneous ferroelectric with a second order phase transition, Zhong et al. 55 write the total free energy in the form

Continuum Solvation Models

It is well known that solvation effects are critical to the structural and dynamical properties of macromolecules. In the present case, the polymeric nanoparticles are produced from a very dilute solution and show strong solvent dependencies of the observed photophysical properties. Therefore, modeling the structure of these PPV-based nanoparticles must include the influence of the solvent. Although a full microscopic description of solvation is possible using MD or mechanics with explicit solvent molecules (there are still approximations in the many-body electrostatic interactions), this approach can be computationally time consuming. As such, considerable research has previously been devoted toward developing reliable implicit solvent models in which the solvent molecules are generally replaced by a structureless dielectric continuum 37,38 . These models greatly increase the speed of the calculation and often avoid some of the convergence problems in explicit models (where longer...

Surface Modification of Nanoparticles

Steric stabilization can be achieved by the adsorption of large molecules such as polymers at the surface of the particles (Fig. 3). Indeed, the coil dimensions of polymers are usually larger than the range over which the attraction forces between colloidal particles are active. Two distinct effects describe this type of stabilization (the volume restriction contribution and the osmotic diffusion), and they both contribute to the interaction free energy 46, 53-54 . First, the fact that the adsorbed molecules are restricted in motion causes a decrease in the configurational entropic contribution to the free energy (Fig. 3). Second, the local increase in concentration of polymer chains between approaching particles results in an osmotic repulsion, since the solvent reestablishes equilibrium by diluting the polymer molecules and separating the particles. This can be described by the energy of free mixing of polymer segments and solvent molecules, calculated by the Flory-Krigbaum theory...

Encapsulated Metallic Nanowires

As was mentioned earlier, CHQ nanotubes arrays can be utilized in promising templates for nanosynthesis. Redox reaction of the nanotube in the presence of silver nitrate leads to the formation of a silver nanowire arrays in the pores (pore size of 8 x 8 A2) of the CHQ nanotube. The wires exist as uniformly oriented three-dimensional arrays of ultrahigh density. The driving force for the formation of these nanowires is the free energy gain due to the reduction-oxidation process. 64,65 The resulting nanowire is composed of four dumbbells, each of which contains two silver atoms, superimposed on one another and crisscrossed in their length.

What are ultimate limits in technology

In domains that build directly on fundamental physical principles, results regarding ultimate limits are often clear and simple the product of the uncertainties in the simultaneously measured position and momentum of a particle must exceed h 4n, the speed of light cannot be exceeded a cycle that writes and erases a bit must dissipate at least ln(2)AT of free energy (Landauer 1961, 1982), and so forth. In domains involving materials and fabrication, however, many results will have a different character not stating a limit precisely, but instead identifying upper or lower bounds on the value of an imprecisely known ultimate limit. For example, the

Conclusions and Discussion

In this chapter the factors responsible for, and categories of, self-assembly are presented and various examples of successful self-assemblies are introduced. Based on the material presented above we may conclude that self-assembly is a method of integration in which the components spontaneously assemble, typically by bouncing around in a solution or gas phase until equilibrium is reached (entropy is maximized and free energy is minimized) and a stable structure is generated.

Single Electron Tunneling Devices Using SWNTs

Where F(N) is the free energy of the central island and T is the temperature 81 . If only one value of N minimizes the thermodynamic potential Q(N) F(N) - NEF, then the system will prefer that single N, and there will be no conductance because the number of particles in the central island cannot change. However, if two values, i.e., N and N+1, minimize the thermodynamic potential, Q(N) Q(N-1), then the system can allow a finite current flow with a small applied voltage because the central island can have states N, N-1, N, N-1, N, N-1, , etc. Q(N) Q(N-1) gives In the low-temperature limit, the free energy F(N) is the ground state energy U(N) of the island. Thus, the current peak appears when If this is negative, then tunneling from electrode i to the island certainly reduces the system energy and is preferred. If positive, oppositely tunneling from the island to electrode i reduces the system energy and is preferred. In the low-temperature limit, the ground-state system energy is...

Friction Mechanisms at the Atomic Scale

As noted in the introduction, static friction implies that the contacting surfaces have locked into a local free energy minimum. There have been many suggestions for how this can happen between nearly every pair of surfaces, whether macroscopic or nanoscale. The purpose of this section is to review some of these mechanisms and discuss their relevance to nanotribological experiments.

Living Water and Hydrophobic Interactions

The polymerization of cytoskeletal polymers and other biomolecules appears to flow upstream against the tide of order proceeding to disorder which is decreed by the second law of thermodynamics. This apparent second law felony is explained by the activities of the water molecules involved (Gutfreund, 1972). Even in bulk aqueous solution, water molecules are somewhat ordered, in that each water molecule can form up to 4 hydrogen bonds with other water molecules. Motion of the water molecules (unless frozen) and reversible breaking and reforming of these hydrogen bonds maintain the far miliar liquid nature of bulk water. Outer surfaces of biomolecules form more stable hydrogen bonding with water, ordering the water surrounding them. This results in a decrease in entropy (increased order) and increase in free energy factors which would strongly inhibit the solubility of biomolecules if not for the effects of hydrophobic interactions. Hydrophobic groups (for example amino acids whose side...

Diffused Phase Transition

Applying the Landau-Ginzburg free energy formulation to an inhomogeneous medium, Li et al. 67 have provided a thermodynamic approach to DPT in mesoscopically inho-mogeneous ferroelectrics. They find that a coherent coupling can take place across the interface between two chemically different dipole-ordered regions. They assume each localized cluster to have a mean-field character, such that the DPT can be understood as an inhomogeneous condensation of localized soft modes.

Duplex DNA Analysis by Capture in the Hemolysin Vestibule

Although only single-stranded DNA fits through the 1.5 nm limiting aperture of a-hemolysin, the pore vestibule can accommodate duplex DNA, up to 12 bp in length.15 Ionic current through the pore is exquisitely sensitive to duplex DNA captured in the vestibule. This method has been used to discriminate among individual molecules that differ by only a single base pair or a single nucleotide.16,17,19,23 For example, Vercoutere et al.16 showed single base pair and single-nucleotide differences among individual blunt-ended DNA hairpin molecules 3 to 8 bp long (see Figure 11.9 for illustration). These molecules caused a partial blockade that last hundreds of times longer than the equivalent length single strand (Figure 11.9A). Blockade amplitudes were directly proportional to the number of base pairs in the stem (Figure 11.9B). The partial blockade durations also correlated with the number of base pairs in the stem, and a log-linear plot of the duration mode for each showed a log-linear fit...

Adhesion Measurements

Surface force apparatus (SFA) and AFMs are used to measure adhesion between two surfaces on micro- to nanoscales. In the SFA, the adhesion of liquid films sandwiched between two curved and smooth surfaces is measured. In an AFM, as discussed earlier, adhesion between a sharp tip and the surface of interest is measured. To measure adhesion between two beams in the mesoscopic length scale, a cantilever beam array (CBA) technique is used 33.113,115-117 . The technique utilizes an array of micromachined polysilicon beams (for Si MEMS applications) anchored to the substrate at one end and with different lengths parallel to the surface. It relies on the peeling and detachment of cantilever beams. Change in free energy, or reversible work done to separate unit areas of two surfaces from contact is called work of adhesion. To measure the work of adhesion, electrostatic actuation is used to bring all beams in contact with the substrate, Fig.33.27 33.113,117 . Once the actuation force is...

Nanostructures from Bulk Undercooled Molten Alloys

It is not clear why the fluxing technique is so effective in obtaining large undercooling for an undercooled melt. Presumably the flux, itself an oxide, helps absorb heterophase impurities in the molten alloy, which are mostly oxides, into itself. For those homophase impurities, the high temperature fluxing forces them to homogenize with the bulk melt. Physically, the large undercooling of a melt below its T1 is attributed to its very different short-range order from a crystalline phase 32 . Phenomenally, the interfacial free energy, ylc, between the liquid and crystalline phases assumes a large value, leading to large AT or large, free-energy change between the liquid and crystalline phases for transformation.

Immobilized Protein Molecules 8421 GCN4

The FRET efficiency distributions obtained from trajectories of trapped molecules under native or fully denatured conditions match the ensemble-measured values. At the midpoint of the denaturation curve the distribution is clearly bimodal, indicating the existence of one dominant free energy barrier under these conditions. This barrier separates two subpopulations of the protein, even though adenylate kinase is certainly not a two-state folder. The peak values of the two subdistributions are shifted from the corresponding values in the fully folded or fully denatured distributions. The shift of the denatured distribution is again an indication of chain collapse due to change in solvent conditions. The shift in the 'folded' distribution suggests that partially open conformations of the protein are populated under midtransition conditions. The distribution is broadened by transitions between these substates of the protein, as can be verified by examining the trajectories...

Theoretical Calculations

13(a) consists of two methano 60 fullerenes, while 13(b) consists of a methano 60 fullerene and a homo 60 fullerene. Generally, a methano 60 fullerene structure is more stable than the corresponding homo 60 fullerene structure 85 . In the case of C121, the computed strain energy of the spiro structure of the bridging atom of 13(a) is larger than 13(b), and this difference compensates for the difference of stability between a methano 60 fullerene and a homo 60 fullerene. Consequently, according to theoretical investigations, Gibbs's free energy of 13(a) is larger than

Observing Folding Steps and Kinetics of Single Membrane Proteins

AFM stylus was lowered to close proximity of the membrane thereby relaxing the unfolded polypeptide chain (Figure 11.11A). At this stage, the system was left to equilibrate for 0.02 to 15 seconds allowing the coiled polypeptide chain to assume its free energy minimum. The efficiency of the refolding process was estimated from repeated folding and unfolding cycles of the molecule. Usually, all major peaks observed during the initial unfolding were detected with intensities similar to original ones if the refolding time delay lasted for 15 s. This indicated that the secondary structures of NhaA refolded and supports the postulation that unfolding and folding of transmembrane helices may be fully reversible (Hunt et al., 1997 Popot et al., 1987).

Heat in a Quantum Computer

Chance to be sent back at each irregularity. Maybe one chance in a hundred, say. That means if I did a computation at each site, I'd have to pass a hundred sites before I got one average scattering. So you're sending electrons through with a velocity v that corresponds to this energy kT. You can write the loss per scattering in terms of free energy if you want, but the entropy loss per scattering is really the irreversible loss, and note that it's the loss per scattering, not per calculation step heavily emphasized, by writing the words on the blackboard . The better you make the computer, the more steps you're going to get per scattering, and, in effect, the less loss per calculation step.

Controlling Cell Interactions With The Surrounding Environment

Besides protein immobilization, adhesion engineering also requires methods to block non-specific protein adsorption. This is achieved by localizing the blocking agent at the surface either by adsorption, or covalent coupling to alkanethiols or silanes. Hydrophilic polymers such as polyethylene oxide, polyethylene glycol, polyacrylamide, agarose, man-nitol or the protein albumin have been used as blocking agents 36, 45 . Multiple factors appear to contribute to the non adhesivity of surfaces including the presence of surface charge, mobility of surface groups and ultimately the free energy cost of adsorption 3 . These chemistries have been critical to the development of surfaces with bio-specific adhesion, by eliminating non-specific, or undesired adhesion.

Potential Applications of CNT Arrays

NT materials scientists at the Institute of Technology in Roorke (India) have developed a microwave-absorbing nanocomposite coating that could make an aircraft or missile almost invisible to hostile radar, thereby significantly contributing to stealth technology. Microwave pulses emitted by radar are used to detect flying aircraft based on the radiation reflected by the metallic body of the aircraft. The (Indian Institute of Technology) IIT scientists claim that stealth technology involving nanocomposite technology will permit fighter or reconnaissance aircraft escape radar surveillance and protect its equipment from electronic jamming or enemy's missile attack. Nanocrystals of barium hexaferrite (BaFe12O19), also known as barium hexagonal ferrite, provide nanoparticles with sizes between 10 and 15 nm, which have the capability to absorb microwave energy. Note coating of nanocom-posite material acts like a radar-absorbing material (RAM). Furthermore, the carbon-based nanocomposite...

Problematic Issues and Present Limitations of the Approach

It follows that it would be foolhardy to base the identification of intermediates on the sign or magnitude of small changes in current level, which are a poor indication of structure. Because individual molecules cannot be identified by spectroscopic techniques, with the possible exception of fluorescence spectroscopy, the old-fashioned tools of mechanistic chemistry must be employed, which include convergence on the same intermediate through different pathways, the chemical trapping or diversion of intermediates, the effects of pH, temperature, and so on on the reaction pathway, the appropriate use of substituent effects (e.g., linear-free energy relationships) and of isotope effects. Given the imprecision inherent in our approach, as presently implemented, only primary hydrogen isotope effects are likely to be of immediate use.

Binding Affinity Of Inorganicbinding Polypeptides

For robust applications of the inorganic-binding polypeptides, determinations of their more fundamental binding parameters such as adsorption and desorption rate constants, or equilibrium adsorption constants are necessary. There is a scarcity of literature reporting quantitative adsorption properties of the inorganic binding proteins on inorganic substrates although these could be achieved using a number of well-established tools including QCM and SPR measurements 43-46 . For example, QCM is based on a mechanical measurement to study the adsorption of proteins and synthetic molecules (such as self-assembling monolayers) on surfaces 43,44 . Here, a quartz crystal disk mounted with an electrode (typically gold), senses the change in resonance frequency due to the change of deposited molecular mass on the substrate surface. When operating in air, QCM can accurately measure submonolayer films but viscosity and thickness become important parameters in liquids. We used QCM to evaluate the...

Environmental degradation or sustainability

On the positive side, the cleaner energy technologies of wind and solar power are now taking off, and well-directed nanotechnology research and development programmes could speed up the transfer to such energy technologies. Nanoengineered materials, making use of the extraordinary properties of nanoparticles such as carbon nanotubes, could play their part in very strong but lightweight blades and other moving parts of wind turbines, eventually bringing down their overall size (aesthetically important), noise impact and manufacturing cost, increasing their generating efficiency. The current increase of solar cell sales at the rate of about 21 per cent a year could be boosted to much higher levels once nanotechnological breakthroughs are incorporated into novel and even more efficient solar energy devices.

Themes and Trends

Porphyrins have been known to aggregate since their first isolation and synthesis. The efficiency in harvesting solar energy, for example, arises from the specific alignment and organization of chlorophyll pigments in antenna complexes and reaction centers. Since many nanotechnological applications of porphyrins require narrowly dispersed nanoaggre-gates, there is a need to predictably and reliably control the size of the particles. Encapsulation of aggregates is an

The Limits to Resources

Today Earth has begun to seem small, arousing concerns that we may deplete its resources. Yet the energy we use totals less than 1 10,000 of the solar energy striking Earth we worry not about the supply of energy as such, but about the supply of convenient gas and oil. Our mines barely scratch the surface of the globe we worry not about the sheer quantity of resources, but about their convenience and cost. When we develop pollution-free nanomachines to gather solar energy and resources, Earth will be able to support a civilization far larger and wealthier than any yet seen, yet suffer less harm than we inflict today. The potential of Earth makes the resources we now use seem insignificant by comparison.

Gasoline frees and Roving Real Estate

Plant it next to the driveway, and it grows into a nice looking tree, complete with a recessed filler hose. Instead of continuing to grow more tree after it matures, it makes gasoline and stores it in the trunk. In fact, a vine that grows in the Amazon produces enough oil that oil can be skimmed off the tapped sap and used to run diesel engines. So, a gasoline tree might be possible to develop simply by using genetic engineering. And if you wonder how roads would be maintained without fuel taxes being paid, consider a self-repairing road that used solar energy to grow more road in place kind of like crabgrass. If the road plant were partly derived from kudzu, road crews might be less busy with repairs and more concerned with keeping the road plant from overgrowing everything

Formulating New Barrier Coatings

While PECVD and ALD methods lead to hermetic coatings, the equipment necessary for these processes is complicated and expensive. An alternate way to develop new protection materials is the sol-gel process, involving alkoxides and alkoxysilanes. Originally, the sol-gel process was used to prepare pure inorganic silica coatings to protect metals, alloys and stainless steel against oxidation and corrosion 27-31 . In addition to silica coatings, other ceramic coatings, such as ZrO. , Al2O3,and SiO2-Al2O3, were used to protect against gas and water corrosion 32 . Reed et al. 27, 28 obtained a multilayer coating on stainless steel, which was used for solar energy applications. Besides protecting against corrosion, these multilayer coatings were used for surface planarization.

Controlling Interfacial Electron Transfer Reactions by Nanomaterial Design

The efficiency of a solar-energy conversion system based on QD-sensitized metal oxide is dominated by electron-transfer reactions at each interface, that is, the kinetics at all interfaces have to be satisfied to optimizie the efficiency. Figure 9.8 shows the potential energy diagram of the interfaces in QD-sensitized metal oxide. For water-splitting reactions, the substrate or electrode is not necessarily employed, since hydrogen and oxygen are potentially evolved on different sites of the QD-sensitized metal-oxide nanomaterial. For applications to photovoltaics and two-electrode-based photoelectrochemical water splitting, a conducting glass is used as a supporting electrode. In this case, there are three interfaces (i) QD metal oxide 44 , (ii) QD electrolyte or QD electron donor 15 and (iii) conducting glass substrate electrolyte 35 . For an increase in efficiency, these three interfaces should be simultaneously optimized. The primary photoinduced charge-separation process occurs at...

Organic Inorganic Optoelectronic Devices

Chemical routes demonstrate longer lifetime, lower power consumption, higher brightness, and better spectral purity, as compared to solid-state LEDs 60 . In recent years, significant progress has been achieved in the synthesis of various types of polymer-nanocomposites, and in understanding their optical and electrical properties. As a result, organic nanocomposite devices, such as light emitting diodes, photovoltaic devices, and solar cells, have been developed using methods of thin organic films, such as chemical and electrostatic self-assembly, contact printing, and spin coating 63 . As compared to solid-state devices, the main advantage of the optoelectronic devices prepared by chemical routes is their cost effectiveness. Moreover, novel composite materials based upon conductive polymers, such as poly(aniline), substituted poly(paraphenylenevinylenes), or poly(thiophenes), when mixed with semiconducting nanoparticles, such as CdS, CdSe, CuS, or ZnS, show new properties of...

Fuel Cells and the Automobile Industry

The first fuel cell was built in 1839 by Welsh judge and scientist Sir William Grove. However, the use of fuel cells as a practical generator began in the 1960s, when the National Space Administration (NASA) chose fuel cells over nuclear power and solar energy to power the Gemini and Apollo spacecraft. Today, fuel cells provide electricity and water on the space shuttles.

Where to Buy Ferrofluids

Turning Sunlight into Electricity. United States Department of Energy. Solar Energies Technologies Program Animations. The photovoltaic effect is the basic physical process through which a PV cell converts sunlight into electricity. Sunlight is composed of photons or particles of solar energy. A site for innovative technologies for contaminated soil and groundwater. Department of Energy http index.htm National Renewable Energy Laboratory (NREL) Sandia National Laboratories http

HTE Applications to PEC Discovery

The materials must come from combinations of elements with sufficient abundance to provide the required 103 m3 yr 1 of solid material required if solar energy conversion is to have a significant impact. If we begin with the approximately 117 elements in the periodic table as potential building blocks and make the economic constraints discussed above, elements which are not at least 1 10 000 as abundant as Si may be eliminated from consideration. Further, the particularly toxic elements (e.g., Pb, Be, Sr) may also be eliminated (or used as a last resort), reducing the entire periodic table to approximately 36 elements, Figure 14.2. Although several specific elements included or omitted from this list might be debated, the general approach of elemental triage is easily defensible. Nonetheless, the number of possible stable combinations of these elements, which might be semiconductors useful for solar-energy conversion, is enormous. No present theory can accurately predict a priori the...

Bottomup growth of fully transparent contact layers of indium tin oxide nanowires for lightemitting devices

Thin layers of indium tin oxide are widely used as transparent coatings and electrodes in solar energy cells1, flat-panel displays2,3, antireflection coatings4, radiation protection5 and lithium-ion battery materials6, because they have the characteristics of low resistivity, strong absorption at ultraviolet wavelengths, high transmission in the visible7, high reflectivity in the far-infrared and strong attenuation in the microwave region. However, there is often a trade-off between electrical conductivity and transparency at visible wavelengths for indium tin oxide and other transparent conducting oxides. Here, we report the growth of layers of indium tin oxide nano-wires that show optimum electronic and photonic properties and demonstrate their use as fully transparent top contacts in the visible to near-infrared region for light-emitting devices.

Nanowires and Rods and Their Applications

Zinc phosphide NWs have a bandgap between 1.4 and 1.6 eV, which make them most attractive for solar energy conversion devices. The on off ratio (the ratio of current under light to dark conditions) is a function of time and impinging light wavelength. The NW resistance is the lowest and the on off ratio is the highest for the high-energy light wavelength of 523 nm 5 . A quick response time less than 1 s and sensitivity when exposed to light combined with low cost and resistance to oxidation make zinc phosphide NWs most ideal for light-sensing applications including solar cells. An array of photodiodes using zinc phosphide NWs could serve as nanooptoelectronic components in high-resolution cameras, high-efficiency solar cells, and various scientific instruments needed for conducting scientific research in remote areas.

Thin film technologies for space structures

Large telescopes, mirrors, antennas (optical, x-ray and radiowave) interplanetary spacecrafts (solar sails) large star coverage structures for planet detection large extremely light solar generators (Solar Power Satellites) intelligent multi-functional structures (e.g. active form control) The illustration 14 shows a conception of a so called Sun Tower, that is based on NASA studies regarding the feasibility of solar power stations in space (Mankins 1995, Feingold 1997). Such structures are supposed to to be several kilometers large and deployed in sun-synchronous or geostationary orbit. The energy might be transferred by means of microwave or laser radiation to earth. Also in Europe and in Japan conceptions for solar power stations in space are discussed. The realization of such conceptions still fails at present due to the extremely high costs of space transportation and technical problems still to be solved (transformation efficiency of the solar cells, possibly with optical...

Clearing the air with nanotechnology

One of our global problems is the increasing amount of carbon dioxide in the air. Instead of waiting around for cheap solar power to eliminate those hydrocarbon-burning power plants at some distant point in the future, we could try to clean up what's coming out of those smokestacks right now. Nanotechnology may be able to provide methods for doing this that are more effective and less expensive than methods we use now.

Room Enough for Dreams

This, then, is the size of the future's promise. Though limits to growth will remain, we will be able to harvest solar power a trillion times greater than all the power now put to human use. From the resources of our solar system, we will be able to create land area a million times that of Earth. With assemblers, automated engineering, and the resources of space we can rapidly gain wealth of a quantity and quality beyond past dreams. Ultimate limits to lifespan will remain, but cell repair technology will make perfect health and indefinitely long lives possible for everyone. These advances will bring new engines of destruction, but they will also make possible active shields and arms control systems able to stabilize peace.

Nanotech Products For Architectural Energy Efficiency

The drive to make any Australian 'house of the future' as energy-efficient as possible is fuelled by the observation that current domestic and commercial buildings draw 6 and 12 respectively of Australia's total electricity generated 5 . A proportion of this is for heating water and for cooking, two areas which will not be further considered here, except to note that some improvements are possible by making greater use of thermal solar power and natural gas. A further proportion of the power is consumed for climate control and lighting and it is specifically these two items that can benefit from the application of nanotechnologies. The situation in other countries is broadly similar, and, for example, it has been stated that about one third of the energy consumed in the USA is used to heat, cool or light buildings 6 , Since the issue of staying warm in cold climates has already received much attention in the literature, the focus of the present paper will be on nanotechnological...

Sampling the Ethical Issues

This category is a broad catch-all for many of the promises of the nano-boosters that have escaped mention already. These promises include unarguable benefits such as overcoming material scarcity, eliminating pollution, creating unlimited low cost solar power, ending poverty, curing cancer or the common cold, restoring extinct species, and making available to everyone cheap and powerful computers. Mark Modzelewski, Executive Director of the Nanobusiness Alliance, states confidently the importance of nanotechnology to the future of mankind cannot be overstated. Nanotech's promise is clean industries, cures for disease, nearly unlimited energy supplies, a continuance of Moore's Law, and perhaps the end of hunger (Ecologist 2003, p. 36). Others suggest advances in the quality of life comparable to those achieved after the industrial revolution (ESRC 2003). One of the reasons for including this broad additional category is to bring attention to the politics of promoting nanotechnology. It...

Automobilevehicle Industry

Nanomaterials could make future automobiles and airplanes lighter and stronger and most of all improve fuel efficiency. Nanotechnology promises to make everything from new coatings that are scratch-resistant and self-cleaning to batteries that last longer for hybrid vehicles. In the longer term, nanotechnology applications will most likely make hydrogen easier to produce and safer to store as a renewable energy source for vehicles. Most experts agree that nanotechnology will play an important role in advancing hydrogen fuel cell technology. See Chapter 8 for more information about hydrogen fuel cells.

Energy Renewable and Clean

Nanotechnology applications could provide decisive technological breakthroughs in the energy sector and have a considerable impact on creating the sustainable energy supply that is required to make the transition from fossil fuels. Possibilities range from gradual short- and medium-term improvements for a more efficient use of conventional and renewable energy sources all the way to completely new, long-term approaches for energy recovery and utilization. With enough political will and funding, nanotechnology could make essential contributions to sustainable energy supply and global climate protection efforts. Nanotechnology innovations could impact each part of the value-added chain in the energy sector energy sources, energy conversion, energy distribution, energy storage, and energy usage. The possible applications range from high-duty nanocomposite materials for lighter and more rugged rotor blades for wind and tidal power plants, to efficient photovoltaic systems, fuel cells, and...

Artificial Evolution How Green is Green Nanotechnology

The term 'Green Nanotechnology' apparently seems a paradox per se, as it challenges both nature and the ecosystem, because the control and manipulation of matter at its very elementary level leads to the creation of new matter not present in the realm of nature. Since the concept 'green' refers primarily to environmental protection and not to the evolutionary process, nanoscience and technology are not inconsistent with 'green'. 'Green Nanotechnology', in fact, has the potential to play a pivotal role in the struggle against the world's most pressing environmental problems. Bio-nanotechnology, for instance, offers a wide spectrum of possibilities for mitigating the adverse effects of environmental degradation, regardless of its causes and sources. In particular, bio-nanotech can provide viable solutions to soil, air and water pollution, and the unsustainable exploitation of natural ressources. These solutions include the support of cleaner production methods, provision of alternative...

Research and Development

The biggest single challenge for the next few decades is creating and distributing energy for 1010 people. We need a minimum of 10 terawatts per year from some new clean energy source by 2050. For worldwide prosperity and peace, energy needs to be cheap, widespread, and available. We can't make it using current technology alone.

In Situ Blends Based on ZnO

Due to the poorly-defined, amorphous nature of the formed TiOx phase, the power conversion efficiency of the resulting photovoltaic cells described in the previous section remained rather low at ca. 0.2 . Improvement can be expected from crystallization of TiO2 . However, this would require high temperatures ( 350 C 214 ) that are not compatible with the presence of the semiconducting polymer. ZnO, on the other hand, is known to crystallize at much lower temperatures 113 . To overcome the limitations encountered in the in situ synthesis of TiO2, Beek et al. introduced in situ-ZnO polymer bulk heterojunction solar cells 215 . The active layer was prepared by spin coating a solution containing an organozinc compound and a conjugated polymer, followed by thermal annealing at moderate temperature. This affords a crystalline ZnO network in the polymer phase. The resulting photovoltaic devices exhibit a significantly increased power conversion efficiency compared to the amorphous in...

Conclusions and Outlook

Films of WO3 are responsive to light well into the visible region of the electromagnetic spectrum (up to 480 nm) provides a distinct advantage over materials such as TiO2, which is only photoresponsive to UV light, prior to the addition of dopants. Therefore, it is significant that nanocrystalline WO3 films have shown anodic photocurrents of up to 6 mA cm 2 in organic solutions. This means that devices can be constructed which couple WO3 film electrodes with a photovoltaic cell, such as amorphous silicon or dye-sensitized TiO2. These tandem cells 5,15 can be considered to operate by combining two photosystems. A nanocrstalline WO3 electrode represents the first photosystem, which absorbs the UV and blue-green portions of the electromagnetic spectrum and drives the photolysis of water. The photovoltaic cell acts as the second photosystem, which absorbs the remaining electromagnetic radiation that is not absorbed by the WO3 and thereby supplies the anodic potential required for the WO3...

Applications Of Nanoparticles

Applications with major fabrication of nanoparticles, on the other hand, can be considered higher-order applications. Examples include light-emitting diodes, low- bandwidth lasers, photovoltaic solar cells, display devices such as OLED (organic light i emitting diode), drug i delivery vehicles, nanoelectronics, photoelectronics, photonics, and heterogeneous catalysis. This topic will be described in Chapter 14.

Structured Porous TiO2

Djurisic et al. followed a similar approach as McGehee et al. to create a TiO, interconnected network structure for photovoltaic applications using a polystyrene-block-polyethylene oxide diblock copolymer (PS-fc-PEO) as the templating agent and MEH-PPV as the light absorbing and hole transporting polymer. The pore structure could be controlled by the amount of Ti precursor provided. The best heterojunc-tion solar cells provided J 3.3 mA cm2, V 0.86 V, FF 0.28, and h 0.71 An interesting approach for nanostructuring TiO2 has been reported by McGehee et al. (Fig.8.19) 198 . Starting with an anodic alumina template (AAO) with pore diameters of 35-65 nm, high modulus polymethylmetacrylate (PMMA) was thermally infiltrated, followed by covering with a poly(dimethylsiloxane) (PDMS) coating and wet etching the AAO template. By subsequently embossing the resulting PMMA mold into a sol gel, a TiO2 replica of the AAO was obtained. These deep narrow straight pores could be useful for hybrid...

Intelligent Inksnow you see them now you dont

When they hear the word semiconductor, most people will think about their role in computers. However, semiconductors also absorb light. Some absorb in the visible range, thus appearing colored, e.g. gray silicon, and others in the UV, e.g. titanium dioxide, thus appearing white (when in microparticulate form) or colorless (when in nanoparticulate form). This light-absorbing feature is used to drive electrons around a circuit in photovoltaic cells, such as the silicon solar cell, but it can also be used to drive chemical reactions at the surface. A good example of the latter is the use of thin (15 nm) titanium dioxide film coatings on self-cleaning glass. When they absorb UV radiation from sunlight, these films can reduce atmospheric oxygen to water and oxidize any organic material on the surface of the glass to its mineral constituents, thereby keeping the surface clean.

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Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

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