Do It Yourself Solar Energy

DIY Home Energy System

This ebook guide teaches you how to escape complete dependence the power grid and learn how to live mostly on your own power and make sure that you are dependent on Yourself. You will be able to slash your energy bill by over 75% and not have to depend on greedy energy companies. The largest energy corporations are a monopoly for a given area, so they do not need to care about customer service or doing right by the people they service. You will learn how to break this monopoly and depend on yourself. Make your home immune to power shortages, blackouts, and energy failures; live free of any worry that the grid will totally fail you! You will learn practical steps such as how to build your own solar panel for less than $60! Once you start relying more on solar power you will be able to easily protect your family from dangerous power outages, and live free! Continue reading...

DIY Home Energy System Overview


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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

A NEW PARADIGM IN SOLAR ENERGY A NEW PARADIGM IN SOLAR ENERGY The above is due to technical control of the deposition process using a technique called chemical vapor deposition. Without such control, such a disruptive technology would not be on the market. It is disruptive because, in the face of the new threat posed by this highly competitive technology, manufacturers of traditional silicon solar panels reacted by ramping production, aiming to reduce cost by economies of scale. This, in its turn, led to oversupply of polysilicon (the raw material for Si-based solar cells) from silicon manufacturers.2) The overall result is that, in early 2009, solar modules in Europe and in the rest of the world were selling at 1.7 W'1. Solar energy for the masses is now a reality At present, most existing production tools in the solar industry have a 10-30 megawatt (MW) annual production capacity. A single machine with a gigawatt throughput would be highly desirable, leading to far higher returns on...

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...

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

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. Established in 2008, the Union for the Mediterranean consists of 42 countries and has a major project a Mediterranean Solar Plan to install concentrating solar power in the deserts and feed huge Established in 2008, the Union for the Mediterranean consists of 42 countries and has a major project a Mediterranean Solar Plan to install concentrating solar power in the deserts and feed huge

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.

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)

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.''

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...

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...

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

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 was observed and solar cell efficiency as high as 1.7 was achieved for the longest nanorods. If nanorods are replaced by branched nanocrystals, the EQE almost double and solar cell efficiencies of 1.8 can be achieved. Various strategies have been applied to enhance the solar cell efficiency by modifying the inorganic semiconductor, by tailoring the composition of the blend or the shape of the nanocrystal, as for example, in branched cadmium telluride (CdTe) tetrapods 114 . Although the increase in efficiency can be achieved by modification of the shape of the inorganic semiconductor, another problem arises from the fact that both inorganic semiconductors and some conjugated polymers (e.g., P3HT)...

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...

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...

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

Fueling Energy with Nano

Konarka Technologies (http produces solar panels with a difference Their light-activated power plastic, which contains titanium oxide nanoparticles coated with a dye, is cheaper to produce and more lightweight than solar panels. This material also uses more of the light spectrum than traditional solar cells so it can store energy from any light source, not just the sun. But Konarka doesn't stop at solar panels they expect to use their power plastic in applications such as cases for cellphones and laptops to save you the trouble of plugging them into the wall to recharge their batteries.

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...

Transport in nanostructures

In the reservoirs the electrons behave more or less as classical particles. This is mainly due to the large volume V of the reservoirs, since a large V leads to a vanishing small energy separation Ae between the quantum states in the reservoir, Ae w h2 2mV 3 . Thus given even the slightest perturbation the electrons will easily and frequently jump back and forth between quantum states whereby the distinct quantum nature is washed out. A given reservoir is characterized by its temperature T and its chemical potential , i.e. the free energy of the lastly added electron. The chemical potential can be changed in a controlled manner by applying a voltage V

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

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...

Advantages and Disadvantages

A-Fe2O3, with its bandgap of 2.2 eV, is one of the most attractive materials for harvesting solar energy for hydrogen generation through the splitting of water in PEC cells. Moreover, a-Fe2O3 is a stable material, which usually does not corrode in contact with most electrolytes over a wide range of pH. Being a low-cost and readily available material, it has always been the material of choice in studies related to photosplitting of water. PEC properties of a-Fe2O3 were extensively studied in the 1970s and 1980s and, despite several advantages, it was labeled as a poor photoelectrode, mainly due to (i) its band edges not being properly aligned to the redox levels for hydrogen oxygen evolution via splitting of water, (ii) large recombination rates of photogenerated carriers and (iii) short diffusion lengths of holes. The high resistance associated with a-Fe2O3 is another drawback leading to poor electrical conduction through the bulk material.

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

The majority of commercial solar cells are made of silicon 64 . The technology of silicon solar cells has reached a state of perfection, resulting in a high efficiency of solar energy conversion (up to 28 ) 65 . This is close to the theoretical limit of silicon solar cells. At the same time, solar cells made of other semiconductor materials, such as II-VI and III-V (e.g., cascaded heterojunctions), are able to achieve much higher efficiency, up to 70 65 . Another important factor in solar cell development is the cost. Monocrystalline silicon devices are expensive though effective. A search for alternative materials (e.g., other semiconductors, organic materials, polymers, or composite heterostructures) for photovoltaic devices and solar cells is constantly being pursued. For example, less expensive polycrystalline silicon devices are not as effective as the monocrystalline devices, but this lower efficiency does not prevent their applications in a number of areas where the maximal...

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.

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...

VLS Method for Nanowire Synthesis

Oxide Assisted Growth Nanowires

Reduction of the average wire diameter to the nanometer scale requires the generation of nanosized catalyst droplets. Due to the balance between the liquid-vapor surface free energy and the free energy of condensation, however, the size of a liquid droplet, in equilibrium with its vapor, is usually limited to the micrometer range. This obstacle was overcome in recent years by several new methodologies 1) Advances in the synthesis of metal nanoclusters have made monodis-persed nanoparticles commercially available. These can be dispersed on a solid substrate in high dilution so that when the temperature is raised above the melting point, the liquid clusters do not aggregate 4.59 . 2) Alternatively, metal islands of nanoscale sizes can self-form when a strained thin layer is grown or heat treated on a non-epitaxial substrate 4.50 . 3) Laser-assisted catalytic VLS growth is a method used to generate nanowires under nonequilibrium conditions. By laser ablation of a target containing both...

Simulation of Microfabrication Processes

Etching, polishing and deposition produce topography on a wafer. This build-up of topography is difficult to simulate because it involves multiphysics and chemistry - plasmas, fluid dynamics and surface chemical reactions. Film deposition simulators depend on atom arrival angles that are not physical constants like dif-fusivities but are parameters sensitive to experimental conditions. Etching reactions are complex interactions between the chemical contributions (spontaneous etching, free energy considerations) and physical processes (e.g., ion bombardment enhanced desorption). Topography process simulators are usually semiempirical some important model parameters are extracted from experiments without fundamental physical validation.

Amorphous Diamond Solar Cell

When the applied bias was gradually reduced to zero, the current enhanced by xenon lamp was not dependent on the bias. Hence, the field emission could be triggered by sunshine directly without adding an external bias. However, the current density was too low to be useful as a solar panel unless the vacuum gap could be reduced further from 7 x. is radiation superhard and it would not be susceptible to UV damage. Amorphous silicon solar cells have the advantages of thin film and low cost, but the aging problem of UV damage makes it less useful so more costly crystalline silicon plates are used as solar panels. It would appear that amorphous diamond coating of amorphous silicon solar cells could boost both the energy conversion efficiency and the longevity of the service. Figure 9.16. The solar absorbed energy of CIGS is the highest among various thin films (shown in figure) with a theoretical conversion efficiency of 25 (top diagram). One example of CIGS solar panel (bottom diagram) is...

Tungsten Oxide as a Catalyst

Because it also has a large band gap, combining zinc oxide with tungsten oxide will not solve the problem of solar powered oxidation. However, the large band gap does make for a large driving force for catalysis, allowing reactions with larger activation energies. In this case, Sakthivel et al. found that the photo-generated electrons created in the zinc oxide reduce sites in the tungsten oxide to a W+5 state.47 This mechanism confirms that proposed by Kohler and Gopel, that reduced W+5 acts as the active catalytic site. As a result of this effect combined with enhanced charge carrier separation, Sakthivel et al. found that adding WO3 to zinc oxide significantly enhanced its photocatalytic activity. Torres-Garcia et al. also investigated a WOj-ZnO system for the purpose of oxidative desulfurization of oil refinery products.48 They report that the stoichiometry of their tungsten oxide appears to be about WO3 based on Raman spectroscopy. In comparative experiments to investigate the...

Nanocrystallization During Melt Quenching

The synthesis of a two-phase nanostructure clearly involves copious nucleation. One factor that can increase the opportunity for high nucleation rates is the relatively slow growth for crystals that require solute redistribution. Furthermore, during continuous cooling, the rate of recalescence after the initial nucleation event depends on the crystal growth rate. If it is slow, the melt may be undercooled further, permitting a rapid rise in the nucleation rate. 12 Moreover, the two-phase nano-structures that are developed during melt spinning identify an important class of metastable microstructure that is available in the form of very high grain densities of the equilibrium phases that were observed to range from 1018 to 1021m-3. A high density of grains for a two-phase mixture is metastable because of a high incoherent interphase boundary area. For example, with a grain size of 0.12 mm and an interphase boundary energy in the range of 500-1000 mJm-2 that is typical for incoherent...

Biocompatibility Of Nanoporous Implants

The site and the extent of injury created in the implantation, biomaterial chemical composition, surface free energy, surface charge, porosity, roughness, and implant size and shape, all govern the degree of fibrosis and vascularization 3 . A thin fibrous tissue reaction

Solid Carbon Source Based Production Techniques for Carbon Nanotubes

Among the different SWNT production techniques, the three processes (laser ablation, solar energy, and electric arc) presented in this section have at least two common points a high temperature (1,000K < T < 6,000 K) medium and the fact that the carbon source originates from the erosion of solid graphite. In spite of these common points, both the morphologies of the carbon nanostructures and the SWNT yields can differ notably with respect to the experimental conditions.

Nanoscience and technology have the potential to make a big impact on energy problems

Two recent reports1,2, published by the Basic Energy Sciences Advisory Committee (BESAC) of the US Department of Energy paint an enticing picture of a sustainable and prosperous future facilitated by new technologies. The large-scale use of solar energy will be made possible by new solar cells, which are both cheap and efficient, and by the development of biomimetic refineries using sunlight, carbon dioxide and water to produce liquid fuels. New batteries or nanoengineered supercapacitors will permit the storage of cleanly generated energy, and new superconducting cables will underpin a new electrical grid. Older energy technologies, such as nuclear power, will be rejuvenated by improved materials that will allow them to operate more reliably at higher temperatures, and energy will be saved throughout the economy by the widespread use of solid-state lighting and new catalysts for industrial processes. Will any of this be implemented Many scientists look forward to the new US...

Limitations of Macroscopic WO3

The above example illustrates the intrinsic limitations in efficiency associated with the use of indirect optical transition semiconductors, such as WO3, as sunlight-driven photoelectrodes. Given the low absorption coefficients, a, in WO3 for photons with energies close to the bandgap, the optical penetration depth, 1 a, for light of visible wavelengths may be of the order of several micrometers 6,13 . In addition to this, the hole diffusion length, Lp, in materials with an indirect optical transition, is quite low, about 0.15 mm in WO3 11 an efficient separation of the electron hole pairs would require the establishment of a potentially wide space-charge layer in order to match 1 a. A simple estimate shows that even for the case of a semiconductor with moderate doping levels, that is, ND 1016cm 3, and a band bending as large as 1 V, the width of the space-charge layer in WO3 does not exceed 0.8 mm 13 . This is still less than optical penetration depths for visible wavelengths. Given...

Bonding of Gold Nanoparticles on TiO2110 in Different Oxidation States

Tio2 110 Surface

Transition-metal nanoparticles are interesting from the perspective of both fundamental studies and applications, and in recent years specifically gold (Au) nanoparticles have attracted great attention. The main reason for this is the surprising catalytic activity of small Au nanoparticles dispersed on oxide supports for numerous reactions 97 102 , but other potential uses, such as in photocatalysis 3,103 110 and solar energy conversion 111,112 have also triggered intense research activity into Au nanoparticles on Ti02 supports.

Self Driven Methods for Movement

A similar observation to that of the moving mercury drop and camphor systems but occurring as a result of a different mechanism is responsible for the dancing like movement of nanoscale Tin (Sn), approximately 0.60 p,m in size on copper (111) surfaces.7 In the Sn Cu system, Sn is deposited onto a copper (111) surface. The Sn object moves around the surface in a non-Brownian fashion as an alloy of bronze is formed at the interface of the two surfaces. Brownian motion is described as movement arising from random thermal fluctuations lacking a defined direction of movement. The interaction of the residual Sn with the bronze surface is energetically unfavorable therefore, the Sn moves to Cu regions to avoid interaction with the bronze thereby minimizing surface free energy.

Liquid Phase Film Formation

For films formed from a liquid solution, bulk properties of the film and substrate determine the step coverage of the formed layer. Important phenomena to consider are surface free energy, wettability, and viscosity and include inertia effects caused by fast rotation in a spindle as in spin coating. In general, the term planarization is used in such cases. In the ideal case, the deposited film will perfectly fill any surface irregularity and forms a flat surface as shown in Figure 48. This result is then called full or ideal planarization.

Thermodynamic and Kinetic Properties ofWOx Reactions

Based on the standard Gibbs free energy of the various oxides, three triple points can be calculated WO2.72, WO2.9, WO2 at about 600 C, WO29, WO3, WO2 at about 270 C, and WO2, WO2.72, W at 1480 C. Using this data, a phase diagram can be constructed. The stability of the various oxides is shown in Fig. 8.2 with respect to the partial pressures of H2O and H2, and temperature. Because all of these compositions are equilibrium compositions, any of them can be produced simply by annealing W or WO3 at the given partial pressure ratio and temperature.

The Cohesive Energy Density Of Polymer Liquids

The solubility parameter (5) is defined as the square root of the CED. This quantity was indroduced by Hildebrand2 and used as a predictor of liquid-liquid solubility. The enthalpy of mixing is proportional to square of the difference (81-82) in the solubility parameters for the two liquids. Thus in combination with the entropy of mixing, the magnitude of this quantity determines the free energy of mixing. For polymers, where we do not have an experimental method for the determination of the CED of the liquid, we cannot expect to be able to make accurate predictions for the enthalpy of mixing. This point is elaborated further below.

Prokaryote to Eukaryote Symbiotic Jump

We are all eukaryotes, as are all animals and nearly all plants existing on earth today. Eukaryotic cells differ from their prokaryotic ancestors by having organized cell interiors (cytoplasm or protoplasm) including separate membrane enclosed compartments (nuclei) which contain, among other structures, chromosomes DNA libraries and their supportive proteins. Eukaryotic cytoplasm usually contains mitochondria, chemical energy factories which utilize oxygen to generate ATP to fuel cellular activities (respiration) and, within green plants, chloroplasts which convert solar energy to chemical energy foodstuffs (photosynthesis).

Chemical Anchoring And Deanchoring

For metal atoms the state of lowest Gibbs Free Energy is achieved when they are organized in a macroscopic polyhedron. High dispersion on a support requires strong chemical interaction between metal and support, conventionally called chemical anchoring. The formation of solid particles either from the vapor or from an adsorbed precursor is dominated by two kinetic processes

Nanotechnology and Our Energy Challenge

It's actually not clear that there is enough coal that's really efficiently, cheaply producible. It's interesting that when you look for terawatts, all the other answers are nuclear. Solar energy is a nuclear energy source, of course. Thus if you like nuclear and if you like nuclear fusion, you'll love the sun. Every day, even though vast amounts of the solar energy go someplace else, 165,000 terawatts hit the Earth. We need only 20 terawatts to completely solve the world's energy needs. This is a vast energy source. We just don't know how to get it cheaply yet.

Oscillating Reactions

A closed chemical system (i.e., no flow in or out) evolves in time towards a stable equilibrium state, at which the free energy is minimal. Interestingly, while free energy always decreases monotonically towards this equilibrium value, the concentrations of the participating chemical species may evolve nonmonotoni-cally, exhibiting oscillatory or even chaotic behaviors. Necessary (but not sufficient) conditions for such chemical oscillations include autocatalysis and nonlinear rate laws.

Transition Metal Oxides And Oxoions

A partially oxidized intermediate to either jump to the gas phase or react further with the oxide, finally leaving it as CO2 + H2O. Selectivity thus depends on the steepness of the curve relating the Gibbs Free Energy of removing oxygen from the solid to the extent of its reduction.33 This gradient will depend on the size of the entity from which one or more oxygen atoms have to be removed. All other parameters being equal, this model leads us to expect that very small particles should be more selective oxidation catalysts than macroscopic oxides.

Solution Phase Methods Based on Hydrothermal Synthesis

Autoclave For Hydrothermal Synthesis

The chemistry aspects of ZnO growth in a hydrothermal alkali environment has been reviewed previously by Demianets et al. 17 , as well as Vayssieres 18,19 . Vayssieres proposed that controlling the interfacial tension is the key to controlling the shape and orientation of crystallites growing on a substrate from aqueous precursors. In an aqueous system, crystal nucleation will be induced when the solution is supersaturated. Initial nucleation can occur either in solution (homogeneous), or on the surfaces of solid phases (heterogeneous), depending on the net interfacial energy of the system. If the interaction between the growing nucleus and a substrate surface represents a lower net interfacial energy, heterogeneous nucleation is favored over homogeneous nucleation. It is well known that crystal-substrate adhesion energies (due to interfacial bond formation minus interfacial strain) can be dominant contributors to the net free energy for heterogeneous nucleation 20 . Thus far, almost...

Comparison ofPhase Transitions Between Small and Large Systems

Order to compare phase transitions in small and large systems these investigators used the following criteria, which are in common between all systems whether small, intermediate or large They proposed that the essential condition to be considered for local stability (as well as metastability) of any form of matter, is the occurrence of a local minimum in the free energy, for fixed external variables, usually intensive, with respect to some suitable order parameter 17,18 . They also considered the equilibrium constant K(7) L S . In this expression L represents the amount of liquid phase and 5 represents the amount of solid phase. This essential relationship determines the relative proportion of two locally stable phases (for example a liquid and a solid phase) with different free energies. Similar to the principle of chemical equilibrium, one may assume the following general expression will hold for the equilibrium constant, K(T) of two phases in contact with respect to their free...

Harnessing Nanotechnology for Sustainable Development

Energy Storage, Production and Conversion Chronic power shortages and increased need for energy resources because of the rapidly growing population and economies of the developing world, are posing challenges to the energy market. Since almost all sources of energy are not renewable, the world will soon face a global energy supply problem. Solar energy is an interesting and valid alternative, especially in the tropical sunny South. Scientific studies have demonstrated that nanoscale techniques involving nanotubes and nanoparticles lead to increased conversion efficiencies. Semiconducting particles of titanium dioxide, coated with light-absorbing dyes bathed in an electrolyte and embedded in plastic films, are cheap and easy to manufacture and offer a viable alternative to conventional energy production and storage. Because of their low cost-structure, photovoltaics using nanotech constitute a valid alternative for overcoming the problem of power shortage, especially in the developing...

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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