Micromachining to create micron-sized structures came into existence with microelectronic fabrication (photolithography, in particular) as the basis. But it does not have to be that way; many researchers are exploring non-lithography alternatives. A big advantage of photolithography is batch-processing and it is accompanying economic incentive when the volume of products is very large. A serial-process like macro-scale milling or drilling is not likely to be economical. But some specialized applications may justify even a serial process. For exploratory purposes, especially in the academic and industrial research labs, the no lithography processes are very attractive. A few processes of that kind are listed below. Some remove material and others add material.
A series of parallel plate capacitors were printed to determine the dielectric properties of the printed PI thin films as illustrated in Fig- ure 2(a). Two, three, and four layers of PI squares (size 7 mm 3 7 mm) were printed on to Aluminum substrates, followed by three layers of silver nanoparticle ink (Advanced Nano Products Co. Ltd) printed (5 mm 3 5 mm) on top of the PI. Apart from using a nor- mal pattern in Figure 2(b), a pattern with 30% overlap between each line was also employed to reduce any surface undulations and defects of the PI film surface, as illustrated in Figure 2(c). Figure 4. Sequence of images for drop deposition and solvent evaporation with a time scale in ms; the observation angle of camera was set at around 108 from the horizontal substrate.
direct tunneling current density at thickness below 3 nm. Moreover, the priority of leakage current is ranked high in device performance and reliability as portable devices prevail [3,4]. Thus, high-dielectric-constant materials have been widely studied as a candidate to replace the gate dielectric. The requirements [5~8] for these materials are very severe. For example, these materials must have high thermodynamic stability with silicon. Their diffusion coefficients should be low so that these materials can withstand high processing temperatures. For gate oxides, these materials should form high-quality interfaces with silicon with few interfacial defects and low roughness. And these materials are required to have barriers for electrons and holes of at least 1 eV, in order to have sufficiently low leakage current. Recently, HfO 2 [9,10], ZrO 2 [11~13], and their
Superconducting is a phenomenon of exactly zero electrical resistance and expulsion of magnetic flux fields occurring in certain materials called superconductors when cooled below a characteristic critical temperature. It was discovered by Dutch physicist Heike kamerlingh onnes on April 18, 1911 in leiden. Superconductivity is a quantum mechanical phenomenon. It is characterized by meissner effect , the complete ejection of magnetic field lines from the interior of superconductors during its transitions into superconducting state. The electrical resistance of metallic conductor decreases gradually as temperature is lowered. In ordinary conductors, such as copper or silver, this decrease is limited by impurities and other defects. Even near absolute zero , a real sample of a normal conductor shows some resistance. In a superconductor, the resistance drops abruptly to zero when the material is cooled below its critical temperature. An electric current through a loop of superconducting wire can persist indefinitely with no power source.
There are two primary failure modes for composites: fibre rupture in tension or fibre buckle in compression , both of which result in an increase stress in the material. Thus the stress state of the composite material is the most important determinant of the structure safety . However, it is difficult to obtain a direct reading of the stress within the material, so a measure of the strain, which is the deformation of a solid due to stress is used instead. There are a number of different sensors being developed for composite damage detection, these include self-sensing in the carbon fibres , glass fibre optical sensors  and piezoelectric sensors . Each method has advantages and disadvantages, i.e. self-sensing in carbon fibres requires no added materials, but is limited to carbon composites, while piezoelectric sensors require the sensors to be attached to the composite surface, but multiple readings can be obtained simultaneously.
cooling capacity and COP, respectively. The energy efficiency of thermoelectric refrigerators, based on currently available materials and technology, is still lower than its compressor counterparts. However, a marketable thermoelectric refrigerator can be made with an acceptable COP. More-over, further improvement in the COP may be possible through improving module contact-resistances, thermal interfaces and heat exchangers. With its environmental benefit, a thermoelectric refrigerator provides an alternative to consumers who are environmentally conscious and willing to spend a little bit more money to enjoyed their quiet operation, and more precise and stable temperature control. The results obtained here may provide some guides for the optimal design and operation of practical thermoelectric cooling systems.
thermosetting polyimide, BMI resins have been widely studied. BMI resins are attractive because of their high chemical, corrosion, radiation resistance, as well as their attrition-enduring, insulating, and mechanical properties (Jin et al., 2001; Glatz & Mulhaupt, 1993; Gawdzik et al., 2001). However, the most attractive property is that they have excellent hot/wet stability up to 573–623 K (Gawdzik et al., 2001). Therefore, BMI resins have been widely used for advanced composite materials, multi-layered lamination materials, abrasive materials, sealing materials, molding materials, powder coating, adhesives, etc (Jin et al., 2001; Glatz & Mulhaupt, 1993; Gawdzik et al., 2001). We report here the crystal structure of (I).
It is the conversion of differences in temperature into electric voltage and electric voltage into temperature differences via a thermocouple. Thermoelectric materials are important for devices which are designed from this conversion. High efficiency TE creates power generation devices. There are three effects which are used in thermoelectric i.e., Seebeck effect, Peltier effect and Thomson effect. Whenever the current is passed through a material the heat is generated, it is termed as Joule heating. It is not termed as thermoelectric effect as it is not reversible like Peltier–Seebeck and Thomson effects. They are thermodynamically reversible but Joule heating is not.An extension of the Peltier–Seebeck effect is Thomson effect which is invented by Lord Kelvin. They are used in solid state refrigeration devices. applications of thermoelectricity Avionics, Black box cooling, Calorimeters, CCD (Charged Couple Devices), CID (Charge Induced Devices), Cold chambers, Cold plates, Compact heat exchangers, Night vision equipment, Osmometers, Parametric amplifiers etc.
application may be in data entry and move to awaiting approval or an application that has been approved may move into the cancelled, deleted or in data entry state. It is therefore possible that the number of applications received could decrease from one month to the next if a large amount of applications move to the states in the red boxes (and are not classed as an application received), although this is highly unlikely in practise. Also, due to the changing of states, the sum of monthly application states over the course of the
Many reports are available on utilizing lignin as a filler or an additive (without chemical modification) in various systems such as rubber latexes, starch films, and sunscreens. 30–32 However, the main challenge in such incorporations is that valorization processes that don’t chemically modify lignin before utilizing it in a system, generally can incorporate limited amounts of the material in their respective systems and the reports on this class of incorporation generally utilize a low percentage of lignin in the final material. On the other hand, various studies have focused on adding value to lignin by chemically modifying the macromolecule to make it a better candidate for incorporation in different systems. Several reactions have been used in this research area such as phenolation, 33,34 esterification, 35–37 and oxopropylation, 38–40 all of which aim at replacing an existing component in a specific system with modified lignin and examining the effect of the replacement. Moreover, lignin has also been utilized in advanced functional materials, where many studies have focused on converting the macromolecule into an advanced system with unique and specific properties such as carbon fibres and nanofibers, 41–44 nanocarriers, 45 and hydrogels. 46–48
Advanced Nuclear Materials discusses the major classes of materials suitable for usage in nuclear fission, fusion reactors and high power accelerators, and for diverse functions in fuels. The work addresses the full panorama of contemporary international research in nuclear materials, from Actinides to Zirconium alloys. Considerable changes in the operating performance of fission reactors, along with advances in the plasma physics knowledge required for heating and controlling fusion energy reactions suggest that fission and fusion energy can be important components of the overall energy portfolio for the 21st century and beyond. Advancedmaterials can enable improved reactor performance via increased safety margins and design flexibility, in particular by providing increased strength, thermal creep resistance and superior corrosion and neutron radiation damage resistance.
Advanced Human Computer Interface and Voice Processing Applications in Space Advanced Human Computer Interface and Voice Processing Applications in Space Julie Payette Canadian Space Agency Canadian A[.]
Interest in carbon-based materials such as graphene has grown tremendously in recent years since its isolation by Novoselov and co- workers in 2004 as a single-atom-thick layer of carbon . A large number of publications have discussed applications of graphene in electrochemical energy-storage devices (EESDs). The properties of graphene vary significantly in terms of morphology, lateral dimensions, number of layers and defects. The presence of defects affects the quality of the end material and, consequently, its electrochemical features . Common synthetic methods include mechanical exfoliation, liquid phase exfoliation, reduction of graphene oxide, bottom-up self- assembly by granulation or balling and chemical vapor deposition of hydrocarbons . One commonly employed method is the reduction of graphene oxide (GO) to yield reduced graphene oxide (RGO). The GO is a highly defective form of graphene with a disrupted sp2-bonding network. Reduction of Graphene oxide restores the πnetwork which is the characteristic of conductive graphene . This method allows production of bulk quantities of graphene with high yield at low to medium quality. Graphene–based
materials have a suitable band gap energy and suitable potentials of the conduction band and the valence band edge under UV light. However, there are a few materials that can produce hydrogen from water splitting under visible light because the band gap is narrow and thus the conduction band is less negative than the hydrogen potential level. Band gap narrowing whilst keeping the conduction band edge in the right position is required for visible light photocatalytic water splitting. Apart from the potential of the conduction band edge, a high recombination rate also affects the photocatalytic water splitting. Separation of photogenerated electrons and photogenerated holes is also required. Charge separation may be achieved by adding sacrificial agents such as methanol, ethanol, oxalic acid, KI, EDTA to remove holes or loading charge separator e.g. Pt, Pd, Ag on the surface. 30,32,112,171,172
Since 1950s, studies have been carried out in the field of geopolymers with only one application in mind- as cementitious materials. Hence, the properties of faster setting, better compressive strength and durability of geopolymers over traditional cements have been advantageous. It has been showed that 27 potassium
of green applications. Indeed, in wireless sensing systems, batteries have a finite life time and energy depletion often occurs within few months. Using rechargeable battery and energy harvesting systems will prevent often discarding away old batteries. The new developed energy harvesting system leads to a self-powered system which is a new benefit in the sensing and continuous monitoring.
In the case of a film – modified electrode where the electroactive species is assumed to be fixed at the surface of the electrode, the impedance spectra could be represented by the Randles’s modified equivalent circuit, which contains two transmission lines associated in parallel. These lines are a finite length transmission line and semi-infinite Warburg impedance, respectively, to correspond to a fast and a slow charge transport processes across the lamellar materials. The ideal double-layer capacity is replaced by a constant phase element (CPE), which reflects the double-layer capacitance at the first PB layer interface .
Research will need to be performed to determine irradiated graphite properties from as-received graphite properties. As-received graphite properties are determined by the raw materials and manufacturing process. Important parameters will be identified such as coke and pitch characteristics, and graphitization temperature. A number of different graphites will be selected with carefully varied parameters. Studies will be conducted to establish the as-received properties of the graphites. Selected properties to be measured are: x-ray crystallinity, density, open and closed porosity, pore size and shape distribution, grain size and size distribution, grain orientation and orientation distribution, thermal expansion, thermal contraction, thermal conductivity, absorption cross-section, sonic Young’s modulus, stress-strain behavior, strength and strength distribution (Weibull modulus), and fracture toughness. In addition, chemistry, including impurities, of the graphites will be established. Due to the anisotropy of manufactured graphite, the materials properties will be determined for two orthogonal directions since graphite exhibits transverse isotropy. The graphites will then be irradiated at systematically varied irradiation doses and temperatures significant to HTGRs. Following irradiation, the materials properties will be reevaluated to determine the effect of irradiation and to establish correlations between the initial as-received properties and the post-irradiation properties that could apply to any particular graphite that may be used in HTGRs.