Synthesis of Hybrimers
Siloxane-based hybrid materials hybrimers prepared by sol-gel process present many advantages for the design of materials 60-62, 66, 67, 71 . Firstly, many precursors are commercially available or can be modified or synthesized secondly, the control of precursor reactivity can be achieved by controlling the catalysts thirdly, transparent films or monoliths having good robustness can be easily processed and finally, the resulting materials are not toxic. Figure 13.1 shows a schematic diagram of...
Berciaud Histidine
Angioy, A. M., A. Desogus, I. T. Barbarossa, P. Anderson, and B. S. Hansson 2003 . Extreme sensitivity in an olfactory system. Chem Senses 28 279-284. Asamoah, O. K., J. P. Wuskell, L. M. Loew, and F. Bezanilla 2003 . A fluorometric approach to local electric field measurements in a voltage-gated ion channel. Neuron 37 85-97. Axelrod, D., T. P. Burghardt, and N. L. Thompson 1984 . Total internal reflection fluorescence. Annu Rev Biophys Bioeng 13 247-268. Bacia, K., S. A. Kim, and P. Schwille...
Laser Technology in Micromanufacturing
Department of Mechatronics, Gwangju Institute of Science and Technology, Republic of South Korea Laser technologies are utilised in various fields like micromanufacturing, instrumentation, imaging, medicine, communications, etc. Although each of these fields is as important as others, we will limit our discussion to the application of laser technologies for manufacturing only. Application of lasers to micromanufacturing has several advantages such as noncontact processing, capability of remote...
Nanostructured Lipid Carriers
SLNs produced by high-pressure homogenization at elevated temperature hot homogenization technique are formed during the cooling process of the hot o w emulsion as mentioned above. To summarize occurring disadvantages, the immediate formation of a perfect crystal or formation during the long-term storage can cause drug expulsion. To avoid this, a less ordered lipid matrix with many imperfections is desirable for better accommodation of the drug, especially to avoid drug expulsion during...
Structure of Carbon Nanotubes CNTs
CNTs are surely the most important nanostructures both from a fundamental point of view and for future applications. Initially, CNTs were simply be sorted by single-walled carbon nanotube SWCNT and multi-walled carbon nanotube MWCNT Fig. 11.2 . Paid most attention by scientists and engineers, different types of CNTs have been synthesised via various processes. Y-shaped junctions and rings composed of single wall CNTs are proposed as possible nanosized electronic devices exhibiting quantum...
MorphologiesControlled Synthesis and Optical Properties of Bismuth Tungstate
Lijin Xie, Junfeng Ma,1' Jun Zhou, and Zhongqiang Zhao College of Chemistry and Chemical Engineering, Ocean University of China, Qingdao 266003, China Hua Tian, Yonggang Wang, Jiantao Tao, and Xiaoyi Zhu Institute of Materials Science and Engineering, Ocean University of China, Qingdao 266003, China Well-crystallized bismuth tungstate Bi2W06 powders with different morphologies were successfully synthesized via a low-temperature molten salt method. The powders were characterized by X-ray...
Diamondlike Carbon
Diamond-like carbon can be coated on a variety of substrates including metals e.g. steel , polymers e.g. teflon , and ceramics e.g. glass . The coating provides certain diamond attributes, such as high wear resistance, low frictional coefficient, and extreme chemical inertness. There are different methods that may produce DLC, each with specific characteristics. Figure 10.1 shows the classification of DLC types based on the diamond-like bonding sp3 and graphitic bonding sp2 for carbon atoms,...
Dendrimers
Although linear polymers may be considered to be of nanomeric dimensions, there is one specific group of polymers that is designed to exploit its nanomeric size and characteristics. These are dendrimers and they are large and complex molecules with very well-defined structures. They are almost perfectly monodisperse macromolecules with a regular and highly branched three-dimensional architecture. Dendrimers can act as biologically active carrier molecules in drug delivery, to which can be...
Layered Structures
In studies on nanostructured thin films, layered structures have also attracted the attention of researchers and are known to offer considerably higher phototoelectrochemical and photo-catalytic activity. A combination of small- and large-bandgap material deposited one over the other, as shown in Figure 13.11, may absorb the full solar spectrum more efficiently. If energy-band edges match at the junction, better and efficient separation of photogenerated electrons and holes is possible. Liou et...
Hydrothermal Synthesis and Densification
Yu-Dong Hou,f Lei Hou, Ting-Ting Zhang, Man-Kang Zhu, Hao Wang, and Hui Yan Department of Materials Science and Engineering, Beijing University of Technology, Beijing 100022, China The sol-gel-hydrothermal processing of Nao.8Ko.2 o.5Bio.sTi03 NKBT nanowires as well as their densification behavior were investigated. The morphology and structure analyses indicated that the sol-gel-hydrothermal route led to the formation of phase-pure perovskite NKBT nanowires with diameters of 5080 nm and lengths...
SolitonsDa vydo v
Important biological events involve spatial transfer of energy along protein molecules. One well known example is the contractile curling of myosin heads in muscle contraction, fueled by the hydrolysis of ATP molecules. These quanta of biological energy are equivalent to 0.43 electron volts, only 20 times greater than background energy and insufficient to excite molecular electronic states. Consequently, under usual conditions biological systems do not emit photons. This implied to Davydov 1977...
Chemical Vapor Deposition
Chemical vapor deposition CVD may be defined as the deposition of a solid on a heated surface from a chemical reaction in the vapor phase. It is a versatile process suitable for the manufacturing of coatings, powders, fibers, and monolithic components. It is possible to produce most metals, metal oxides, and non-metallic elements such as carbon and silicon as a large number of compounds including carbides, nitrides, oxides, intermetallics, and many others. The main advantage of CVD is that the...
Scientific World Eugenie Samuel Reich
Plastic Fantastic How the Biggest Fraud in Physics shook the scientific world PALGRAVE MACMILLAN 2009. 272 PP. 15.00 26.95 HARDBACK Sometime in 1999, when I was editor of Physics World magazine, I commissioned Bertram Batlogg, then based at the world-famous Bell Laboratories in Murray Hill, New Jersey, to write an article on cuprate superconductors. As I recall, a first draft arrived a few months later, and I replied with some queries and suggestions. I also recall that it took much longer than...
Castep
CASTEP is an ab initio quantum mechanical program employing density functional theory DFT to simulate the properties of solids, interfaces, and surfaces for a wide range of materials classes including ceramics, semiconductors, and metals. First principle calculations allow researchers to investigate the nature and origin of the electronic, optical, and structural properties of a system without the need for any experimental input other than the atomic number of mass of the constituent atoms....
Reduction of Protein Adsorption
Albumin is a model protein commonly used to study the protein-resistance properties of surfaces 53 . A 15fold reduction of albumin adsorption was found with PEG-coated PEG-PLA nanospheres compared to PLA ones 54 . Similar albumin-rejecting abilities were observed in the case of PLGA nanospheres surface modified by adsorption of PEG-PLA diblock copolymers 55 . Fibrinogen was used as a model blood protein to test the efficacy of the PEG coating on PEG-PACA nanospheres 49 . After freeze-fracture,...
Nucleophilic Addition to Fullerenes
The reactivity of fullerenes toward nucleophiles is caused by their electron deficiency. Numerous reactions with nucleophilic reagents leading to useful and interesting derivatives have been described. The nucleophilic addition to fullerenes corresponds to the common mechanism observed for electron-deficient olefins. A nucleophile A- initially attacks the double bond and a reactive intermediate C-0A- is generated. This can be stabilized in several ways. The product C60AE results from the...
Lamellar Phase and Gel Phase
A liquid crystalline state also called the mesophase of a substance is a state between a pure crystal characterized by a high order of rigid molecules and a pure liquid characterized by rapid molecular motions of disordered molecules 32 . There are dozens of different liquid crystalline states, all characterized by a different degree of molecular mobility and order. Liquid crystals can be produced either by heating a particular crystalline solid called a thermotropic liquid crystal or by...
Growing Interest in Carbon Nanotube
The report of Kroto et al. in 1985 on the discovery of bulkyball, fullerene C60 molecule led into a new beginning in carbon materials and a huge interest in their sciences. Sumio Iijima of NEC Laboratory in Tsukuba observed MWNTs with high-resolution transmission electron microscopy TEM in 1991, and two years later he observed SWNTs. While for the first time, researchers at the William Rice University synthesised bundles of SWNTs in 1996, and most recently, in 2003 Fakhru'l-Razi, Iyuke and...
Reactivity Fate and Lifetime
Nanoparticles can sequester groundwater contaminants via adsorption or complexation , making them immobile, or can degrade or transform them to innocuous compounds. Contaminant transformations by nano-iron, which is a strong reductant, are typically redox reactions. When the oxidant or reductant is the nanoparticle itself, it is considered a reactive nanoparticle Figure 8.2 . A good example of a reactive nanoparticle is TCE dechlorination by nanoiron. Oxidation of Fe0 in the particle provides...
Fouling and Nanofiltration Performance
Most municipal, industrial, and natural waters contain complex mixtures of dissolved, macromolecular colloidal, and particulate matter. Conventional processes used to pretreat NF feed waters fail to remove submicron colloids, macromolecules and dissolved matter. This matter accumulates at the membrane surface and results in severe performance decline a phenomenon known as fouling. Fouling of NF membranes may result in loss of both solvent flux and solute retention. A review of fouling studies...
Magnetization Curve
As indicated in Section 2.2, the magnetic flux B and field H are scaled by the permeability similarly the magnetization M and field H are scaled by the susceptibility x. For ferro- and ferrimagnetic materials, and x are not constants instead they are nonlinear functions that depend on the previous state of magnetization hysteresis . Figure 16 is a plot of B and 0M versus H, known as the BH or MH loop, where and x are the tangents of the curve at different operating H. Note that from Figure 16,...
INTERACTION BETWEEN HYDROGEN AND CNTs
Current theoretical studies of simple physical adsorption on pure carbon nanotubes predict a maximum of 14 wt under low temperature and ideal conditions. The real adsorption process is likely to be more complicated, and the theoretical simulations have the potential for further refinement. In particular, as more quantitative and microscopically in-depth experimental results become available, the model parameters and assumptions will become more realistic. Only some of the experimental results...
Applications of Magnetic Nanocomposites
Application of nanostructure materials is vast and fascinating. The range of application includes cosmetic and sun block, nanofilters, coatings for cutting tools, tennis balls, materials for vehicles, catalysis, sensors, vitamins and additives in food and drug delivery etc. All such applications are for the benefit of mankind. The basic iron oxide and its alloys were the initial soft ferrites which were applied to high frequency applications - heavy duty and light duty multipliers used in cores...
Metal Oxide Nanotubes
Aluminium oxide nanotubes. The anodic oxidation of aluminium in acidic electrolytes, resulting in the formation of a porous film of anodic aluminium oxide AAO consisting of nanotubes, was discovered in a pre-nanoscience era.28 In a typical method, pure aluminium is anodised in the presence of oxalic acid 0.3 mol dm-3 , at a constant cell voltage of 40 V. A long period of ano-disation can improve the regularity of the tube arrangement, towards a hexagonal array of nanotubes.29 AAO films are...
Porous Silicon
The attraction of placing active electronic circuit components into in-vivo drug delivery materials led to the exploration of elemental silicon as a biomaterial. In particular a porous form of Si produced by an electrochemical corrosion reaction has been of interest. Since the pioneering work of Canham and others in the late 90's demonstrating the biocompatibility and biodegradability of porous Si in vitro and in vivo 25-35 , this material has been under intensive investigation for controlled...
Ductility of Nanocrystalline Materials
The ductility of nanocrystalline materials can be examined by tensile testing. In a tensile test ductility is related to the elongation at fracture or the reduction of area at necking at fracture. A classical approach to theoretical consideration of the ductility of nanomaterials is that of Morris 2 , who uses the so-called Consid re construction to describe the respective importance of stress level and work-hardening rate in controlling the geometric instability responsible for the onset of...
SERS as a Tool for Detection of SingleMolecules
There have been several reports of single-molecule detection using SERS in recent years 4-7,113,136,137 . A critical factor in these milestone studies has been the development of exceptional SERS substrates. Most of the reports of single-molecule SERS detection have involved the use of metal colloids in suspensions. For example, Kneipp et al. demonstrated single-molecule detection of crystal violet in both silver 5,6 and colloid suspensions 7 . In these studies, an effective cross-section of...
Peixuan Guo Summary
A controllable, 30-nm imitating DNA-packaging motor was constructed. The motor is driven by six synthetic adenosine triphosphate ATP -binding RNA packaging RNA pRNA monomers, similar to the driving of a bolt with a hex nut. Conformational change and sequential action of the RNA with fivefold viral capsid sixfold pRNA hexamer mismatch could ensure continuous rotation of the motor with ATP as energy. In the presence of ATP and magnesium, a 5- lm synthetic DNA was packaged using this motor. On...
Uv Absorption Of Zro2
C 3640 cm-1 SCHEME 11.1. Surface OH groups Scheme 11.1 .30 IR peak positions of different hydroxyl groups for CeO2 sample are also given in Scheme 11.1. After passing hydrogen and then water at 873 K, the sample was evacuated and the IR spectrum was measured. The intensity of the OH groups on different supports increased in the order Al2O3 lt CeO2-ZrO2 Al2O3 lt NiO 20 -Al2O3 20 -CeO2 6 -ZrO2 54 . Significant amount of surface OH groups were present under reaction conditions. In addition to...
Application Of Sacrificial Oxide In Devices
Sacrificial oxide has been used in IC fabrication as well in MEMS fabrication. This section reviews the use of sacrificial layer in fabrication of different devices. FIGURE 5.4. a Starting wafer, b the hole patterned before doping, c Boron diffusion through the patterned hole, and back side etching, d Complete fabricated single-crystal silicon membrane 83 . In 1965, Nathanson etal. 2,80,81 used sacrificial layer technique to fabricate resonant gate transistors consistent with silicon integrated...
Active Targeting Strategies in Cancer with a Focus on Potential Nanotechnology
3.2 Nanoparticle 3.2.1 Composition and Biocompatibility 22 23 3.3 Nanoparticle 3.3.1 Inherent 3.3.2 Complicating 3.3.3 Safety 3.4 Targeting to Cancer 3.4.1 Cell Surface 3.5 Targeting to 3.5.1 Aberrant 3.5.2 Metabolic 3.6 Fate of 3.6.1 Site of Initial 3.6.2 Distribution to Specific 3.6.3 Intracellular Uptake and
Microtechnological Foundations 33
3.2 Preparation of Thin Layers 37 3.2.1 Condition and Preprocessing of the Substrate Surface 37 3.2.2 Layer Deposition from the Gas Phase 39 3.2.5 Chemical Vapor Deposition 46 3.2.7 Deposition by Spinning Spin Coating 50 3.2.8 Shadow-mask Deposition Techniques 53 3.3 Preparation of Ultrathin Inorganic Layers and Surface-bound Nanoparticles 54 3.3.1 Ultrathin Layers by Vacuum Deposition Processes 54 3.3.2 Deposition of Ultrathin Films from the Liquid Phase 55 3.3.3 In Situ Generation of...
Improving the tribological properties of polymer nanocomposites
There are a number of ways in which the addition of a particle to a polymer can improve its friction and wear properties and all of these have been exploited in the production of nanocomposites. One approach is to reduce the adhesion of the composite to its sliding counterface by adding friction-modifying reinforcements which may also reduce the heat generated in a sliding contact. These friction modifiers may be in the form of low-friction particles which form low-friction transfer layers at...
Surface Characteristics
Surface characteristics contribute to the nanoparticle's solubility, aggregation tendency, ability to traverse biological barriers such as a cell wall , biocompatibility, and targeting ability. The nanoparticle surface is also responsible for interaction and binding with plasma proteins in vivo, which in turn may alter the nanoparticle's distribution and pharmacokinetics. For multifunctional nanoparticles, modifying agents are often attached to the surface to bind to receptors in target tissues...
Disadvantages of Polymeric Nanoparticles
Although polymeric nanoparticles have many advantages such as various fabrication methods, versatile drug loading, and drug release methods , they still have some drawbacks. The main limitation is that some preparation methods use toxic organic solvents that could degrade certain drugs when they come into contact during the formulation process or could be hazardous to the environment as well as to the physiological system Birnbaum et al. 2000 . Other disadvantages include poor drug...
Nanosensors Sensitive Probes for the Biodetection of ROS
In the context of testing, a nanobiosensor can involve a biological molecule that serves as a detector, linker, or mediator, and nanoelectrodes. Various components can be equated with the electronic elements of a sensor, as every component has to transduce the signal generated at the source biomolecule to the detector electrode Figure 6.2 . Consequently, NADH peroxidase Multi-histidine peptide AuNP Figure 6.2 Nanobiosensor assembly based on the atomic coordinates of the NADH peroxidase and MHP...
Intermediate Filaments
The major filamentous components of the cytoskeleton are MT, actin filaments, intermediate filaments IF , and a class of delicate interconnecting fibrils called the microtrabecular lattice MTL which will be described later in this chapter. Here the unknown members of the cytoskeleton, intermediate filaments are reviewed Lazarides, 1980 . Intermediate filaments represent the most nebulous and chemically variable subgroup among the cytoskeleton. Five classes of IF have been distinguished which...
SelfAssembly of Vesicular Systems
Giant unilamellar vesicles GUVs with sizes ranging from 5 to 100 im are intensely studied in diverse areas, focusing on membrane functions such as adhesion, fusion, fission Luisi and Walde 1999 , or generation and properties of nanotubes and network assemblies. A number of methods to create giant vesicles have been reported. One of the methods is based on a dehydration-rehydration procedure described by Criado and Keller 1987 . As a variant, the rehydration of thin dried films obtained after...
Techniques and Instruments Used to Study Nanomaterials
The current boom in nanoscience and nanotechnology is to some extent a result of the recent advances in the methods of investigating and manipulating small objects. Such developments were mostly driven by the improvement in the resolution, reliability and availability of electron microscopy, including scanning SEM and transmittance TEM modes. The recent invention of scanning tunnelling STM and atomic force AFM microscopy, first appearing in 1982 and 1986, respectively,1 also provided additional...
Experimental Methods
The starting materials used in the synthesis were metal nitrates Sm N03 3.6H20 99.9 purity , La N03 3.6H20 99.9 purity , Sr N03 2 98 purity , Co N03 2.6H20 97.7 purity and glycine NH2CH2COOH, 99.5 purity , all from Alfa Aesar. A flow chart showing the various steps involved in the synthesis of powders by the solution-combustion process is shown in Fig. 1. Metal nitrates are employed both as metal precursors and oxidizing agents. Stoichiometric amounts of the metal nitrates, to yield lOg of the...
Polymerclay nanocomposites
PC nanocomposites are an emerging class of organic-inorganic hybrids that contain a relatively low wt of nanometer-sized clay. These were first developed in the late 1980s. The dispersion of the nanometer-sized clay in the polymer matrix significantly improves the mechanical, thermal, barrier properties and flame retardancy of the base polymer. Three main types of nanocomposites can be obtained when clay is dispersed in a polymer matrix. This depends on the nature of the components used,...
Improving Lithium Ion Battery Performance
Lithium ion batteries seem to be everywhere these days. They power most of the electronic devices we carry around with us cellphones, laptops, MP3 players, digital cameras, and so on. They get their name from the lithium ion that moves from the anode to the cathode during discharge and from the cathode to the anode during recharging. Because of their good energy-to-weight ratios, lithium batteries are some of the most energetic rechargeable batteries available today. In terms of weight and...
Size Reduction by Sidewall Transfer
The line width of lithographic features can be drastically reduced if side wall depositions at perpendicularly etched micro- or nanostructures are used as masks in subsequent anisotropic etching or deposition processes. This technique transfers the side-wall topology rather than the original structure to the substrate. It is therefore named sidewall transfer lithography STL . The application of STL to silicon leads to the formation of sub-10-nm structures. The process involves the deposition of...
NanotoxicologyAssessing the Risks
New technology, whether it is a novel cancer treatment or an innovative approach to making a new material, almost always comes with risk. Nano-technologies are no exception. Certain nanofabrication techniques employ toxic chemicals, the production of carbon nanotubes results in dangerous by-products, and the big question as to what degree certain engineered nanoparticles could be harmful to humans and the environment has not yet been answered. The potentially adverse health effects of fine and...
Gallium Arsenide
Crystalline gallium arsenide GaAs is a gold-gray glassy material with the zinc-blende structure. When bound to each other, both gallium and arsenic atoms form tetrahedral bonds. In the industry, GaAs is referred to as a III-V three-five , to indicate that it is a compound semiconductor Figure 2.7. Silicon nitride appears in many crystalline configurations. The structure of a and of p Si3N4 are based on vertical stacks of SiN4 tetrahedra, as shown in I and II respectively. Figure 2.7. Silicon...
Peptoids
We have discussed biomimetic systems with special emphasis on vesicles inspired by cell membranes and viral envelopes. At this point we turn our interest on describing mimics of proteins and DNA. The first of these, the poly N-substituted glycine , peptoid, was developed in a combinatorial drug discovery program by Simon and coworkers 70,71 , and its chemical structure is described in Figure 3.4. The general chemical structure of polypeptoids was inspired by polypeptides, with the difference...
Masako Yudasaka
Nanotubulites, International Cooperative Research Project, Japan Science Technology Corporation, C o NEC 34 Miyukigaoka, Tsukuba, Ibaraki 305-8504, Japan Metal catalysts take forms of nanometer-sized particles in the condensed carbon phase and catalyze the growth of single-wall carbon nanotubes at about 1200 C. The good metal catalysts in forming single-wall carbon nanotubes must satisfy at least three conditions 1 be a good graphitization catalyst, 2 have low solubility in graphite, and 3 have...
Nanoclays in Asphalt Binders and Mixtures
Pavement researchers have suggested that nanoclays have interesting performance enhancing characteristics that could improve the mechanical strength properties of both asphalt binders and mixtures. In one of such notable studies, it has been shown that polymeric nanoclay composites can improve the physical, chemical and mechanical properties of asphalt binder systems when the nanoclays are evenly dispersed at the nanoscopic level within the binder system Jahromi and Khodaii 2009 . Nanofil-15...
Strengthening Mechanisms
The hardening mechanism of nanocomposites should be more complicated 165, 385, 386 than that in coarse-grained polycrystalline materials. The hardness of nanocomposites is most precisely approximated by the Hall-Petch equation, but currently there is no agreement on the strengthening mechanism of nanocomposites. A few strengthening models of nanostructured materials at nanoscale thicknesses of the bilayer repeat period below the Hall-Petch breakdown were proposed Orowan mechanism 344, 387-393 ,...
Todd D Krauss
The development of optically based biological sensors that can detect multiple analytes has revolutionized molecular biology. In addition to greatly aiding basic research, these devices have led to pioneering applications in gene expression, detection of biowarfare agents, medical diagnostics, drug discovery and forensics. However, most optically based biosensors, like the well-known DNA chip1, have limitations such as a slow response or unsuitability for in vivo use. On page 114 of this issue,...