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High Mobility (high + mobility)
Terms modified by High Mobility Selected AbstractsTransistor Paint: Environmentally Stable N -alkyldithienopyrrole and Bithiazole-Based Copolymer Thin-Film Transistors Show Reproducible High Mobilities without AnnealingADVANCED FUNCTIONAL MATERIALS, Issue 21 2009Junying Liu Abstract New solution processable 4-(2-hexyldecan)- 4H -bisthieno[2,3- d:3,,2,- b]pyrrole and 4,4,-dialkyl-2,2,-bithiazole-based copolymers (PBTzDTPs) are synthesized with excellent FET performance. These novel copolymers have considerable potential in printable electronics as they have high charge carrier mobilities, excellent air stability, good solution processibility, and no requirement for post-deposition thermal annealing, all requirements for this field of application. The thin film transistors fabricated from PBTzDTPs achieve field effect mobilities as high as 0.14,cm2 V,1 s,1 with current on/off ratios up to 106 without thermal annealing. In addition, the devices exhibit stable performance in air, showing no significant degradation over 60 days. Moreover, the polymers described here provide an excellent example of the systems in which higher mobility performance does not require higher crystalline, long-range ordered structures. Such a system appears to be particularly promising for rapid fabrication techniques, where kinetic conditions usually prevent the development of long-range order. [source] Air-Operable, High-Mobility Organic Transistors with Semifluorinated Side Chains and Unsubstituted Naphthalenetetracarboxylic Diimide Cores: High Mobility and Environmental and Bias Stress Stability from the Perfluorooctylpropyl Side ChainADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Byung Jun Jung Abstract N,N,-bis(3-(perfluoroctyl)propyl)-1,4,5,8-naphthalenetetracarboxylic acid diimide (8,3-NTCDI) was newly synthesized, as were related fluorooctylalkyl-NTCDIs and alkyl-NTCDIs. The 8,3-NTCDI-based organic thin-film transistor (OTFT) on an octadecyltrimethoxysilane (OTS)-treated Si/SiO2 substrate shows apparent electron mobility approaching 0.7 cm2 V -1s -1 in air. The fluorooctylethyl-NTCDI (8,2-NTCDI) and fluorooctylbutyl-NTCDI (8,4-NTCDI) had significantly inferior properties even though their chemical structures are only slightly different, and nonfluorinated decyl and undecyl NTCDIs did not operate predictably in air. From atomic force microscopy, the 8,3-NTCDI active layer deposited with the substrate at 120 °C forms a polycrystalline film with grain sizes >4,m. Mobilities were stable in air for one week. After 100 days in air, the average mobility of three OTFTs decreased from 0.62 to 0.12 cm2 V -1s -1, but stabilized thereafter. The threshold voltage (VT) increased by 15 V in air, but only by 3 V under nitrogen, after one week. On/off ratios were stable in air throughout. We also investigated transistor stability to gate bias stress. The transistor on hexamethlydisilazane (HMDS) is more stable than that on OTS with mobility comparable to amorphous Si TFTs. VT shifts caused by ON (30 V) and OFF (,20 V) gate bias stress for the HMDS samples for 1 hour were 1.79 V and 1.27 V under N2, respectively, and relaxation times of 106 and 107 s were obtained using the stretched exponential model. These performances are promising for use in transparent display backplanes. [source] High Mobility and Luminescent Efficiency in Organic Single-Crystal Light-Emitting TransistorsADVANCED FUNCTIONAL MATERIALS, Issue 11 2009Satria Zulkarnaen Bisri Abstract A high-performance ambipolar light-emitting transistor (LET) that has high hole and electron mobilities and excellent luminescence characteristics is described. By using this device, a conspicuous light-confined edge emission and current-density-dependent spectral evolution are observed. These findings will result in broader utilization of device potential and they provide a promising route for realizing electrically driven organic lasers. [source] 2,7-Carbazolenevinylene-Based Oligomer Thin-Film Transistors: High Mobility Through Structural Ordering,ADVANCED FUNCTIONAL MATERIALS, Issue 10 2005N. Drolet Abstract We have fabricated organic field-effect transistors based on thin films of 2,7-carbazole oligomeric semiconductors 1,4-bis(vinylene-(N -hexyl-2-carbazole))phenylene (CPC), 1,4-bis(vinylene-(N,-methyl-7,-hexyl-2,-carbazole))benzene (RCPCR), N -hexyl-2,7-bis(vinylene-(N -hexyl-2-carbazole))carbazole (CCC), and N -methyl-2,7-bis(vinylene-(7-hexyl- N -methyl-2-carbazole))carbazole (RCCCR). The organic semiconductors are deposited by thermal evaporation on bare and chemically modified silicon dioxide surfaces (SiO2/Si) held at different temperatures varying from 25 to 200,°C during deposition. The resulting thin films have been characterized using UV-vis and Fourier-transform infrared spectroscopies, scanning electron microscopy, and X-ray diffraction, and the observed top-contact transistor performances have been correlated with thin-film properties. We found that these new ,-conjugated oligomers can form highly ordered structures and reach high hole mobilities. Devices using CPC as the active semiconductor have exhibited mobilities as high as 0.3,cm2,V,1,s,1 with on/off current ratios of up to 107. These features make CPC and 2,7-carbazolenevinylene-based oligomers attractive candidates for device applications. [source] Microstructural Origin of High Mobility in High-Performance Poly(thieno-thiophene) Thin-Film TransistorsADVANCED MATERIALS, Issue 6 2010Chenchen Wang High-mobility PBTTT thin-film transistors are modeled with a mobility edge model and compared with P3HT. Their improved performance is not due to a low trap density but rather due to high mobility in the crystallites. Characterization of delaminated films with transmission electron microscopy and atomic force microscopy indicates terraces that are composed of nanometer-scale features (see figure). [source] A New Poly(thienylenevinylene) Derivative with High Mobility and Oxidative Stability for Organic Thin-Film Transistors and Solar CellsADVANCED MATERIALS, Issue 27 2009Bogyu Lim A novel thiophene-thienylenevinylene copolymer is synthesized and evaluated for use in organic field-effect transistors and organic solar cells. PETV12T shows good solution processability and high structural organization after annealing. Organic thin-film transistors based on the polymer exhibit high mobility and a high resistance to oxidation. In addition, PETV12T shows potential as an electron donor in bulk heterojunction solar cells. [source] Why we're still arguing about the Pleistocene occupation of the AmericasEVOLUTIONARY ANTHROPOLOGY, Issue 2 2007Nicole M. Waguespack Abstract Although empirical issues surround the when, how, and who questions of New World colonization, much of current debate hinges on theoretical problems because it has become clear that our understanding of New World colonization is not resolute.1 In fact, the central issues of debate have remained essentially unchanged for the last eighty years. The now classic and probably incorrect story of New World colonization begins in Late Pleistocene Siberia, with small a population of foragers migrating across Beringia (,13,500 calendar years before present (CYBP) (Box 1) through an ice-free corridor and traveling through the interior of North America. High mobility and rapid population growth spurred southward expansion into increasingly distant unoccupied regions, culminating in the settlement of the Southern Cone of South America. Armed with the skills and weapons needed to maintain a megafauna-based subsistence strategy, early colonists necessarily had the adaptive flexibility to colonize a diverse array of Pleistocene landscapes. For a time, this scenario seemed well substantiated. The earliest sites in South America were younger than their northern counterparts, fluted artifacts were found across the Americas within a brief temporal window, and projectile points capable of wounding elephant-sized prey were commonly found in association with proboscidean remains. The Bering Land Bridge connecting Asia to Alaska and an ice-free corridor providing passage between the Pleistocene ice masses of Canada seemed to provide a clear route of entry for Clovis colonists. However, recent archeological, paleoenvironmental, biological, and theoretical work largely questions the plausibility of these events. [source] Organic Single Crystal Field-effect Transistors Based on 6H -pyrrolo[3,2,b:4,5,b´]bis[1,4]benzothiazine and its DerivativesADVANCED MATERIALS, Issue 22 2010Zhongming Wei Single crystal effect-field transistors (SCFETs) are fabricated based on single crystal micro-ribbons of 6H -pyrrolo[3,2,b:4,5,b´]bis[1,4]benzothiazine and its 6-substituted derivatives (PBBTZ 1,3). High mobility (3.6,cm2 V,1,s,1) and high stability (no significant decrease in one year) are obtained from the devices. The quantum chemically calculated results on the crystals 1,3 (see figure) agrees well with the experimental data. [source] Surface-Modified High- k Oxide Gate Dielectrics for Low-Voltage High-Performance Pentacene Thin-Film Transistors,ADVANCED FUNCTIONAL MATERIALS, Issue 6 2007S. Kim Abstract In this study, pentacene thin-film transistors (TFTs) operating at low voltages with high mobilities and low leakage currents are successfully fabricated by the surface modification of the CeO2,SiO2 gate dielectrics. The surface of the gate dielectric plays a crucial role in determining the performance and electrical reliability of the pentacene TFTs. Nearly hysteresis-free transistors are obtained by passivating the devices with appropriate polymeric dielectrics. After coating with poly(4-vinylphenol) (PVP), the reduced roughness of the surface induces the formation of uniform and large pentacene grains; moreover, ,OH groups on CeO2,SiO2 are terminated by C6H5, resulting in the formation of a more hydrophobic surface. Enhanced pentacene quality and reduced hysteresis is observed in current,voltage (I,V) measurements of the PVP-coated pentacene TFTs. Since grain boundaries and ,OH groups are believed to act as electron traps, an OH-free and smooth gate dielectric leads to a low trap density at the interface between the pentacene and the gate dielectric. The realization of electrically stable devices that can be operated at low voltages makes the OTFTs excellent candidates for future flexible displays and electronics applications. [source] The Influence of Morphology on High-Performance Polymer Field-Effect TransistorsADVANCED MATERIALS, Issue 2 2009Hoi Nok Tsao The influence of molecular packing on the performance of polymer organic field-effect transistors is illustrated in this work. Both close ,-stacking distance and long-range order are important for achieving high mobilities. By aligning the polymers from solution, long-range order is induced, yielding hole mobilities of up to µsat,=,1.4,cm2 V,1 s,1 and current on/off ratios Ion/Ioff of 105. [source] High-Performance Field-Effect Transistor Based on Dibenzo[d,d,]thieno[3,2- b;4,5- b,]dithiophene, an Easily Synthesized Semiconductor with High Ionization Potential,ADVANCED MATERIALS, Issue 19 2007H. Gao Three simple, controlled steps are all it takes to synthesize the title pentacene analogue DBTDT (see figure). The material's high ionization potential, high thermal and photostability, high mobilities, and an on/off ratio larger than 106 at a substrate temperature of ca.,36,°C, as reported here, suggest that DBTDT will be extremely valuable for applications in plastic organic electronics. [source] Electron transport properties of low sheet-resistance two-dimensional electron gases in ultrathin AlN/GaN heterojunctions grown by MBEPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008Yu Cao Abstract A study of the transport properties of polarizationinduced 2DEGs at MBE-grown single AlN/GaN heterostructures with different growth rates is reported. It is observed that faster growth rates lead to high mobilities, approaching , 1600 cm2/Vs at 300 K and , 6000 cm2/Vs at low temperatures for ultrathin (2.3 nm AlN/GaN) heterojunctions. By using a theoretical model in conjunction with experimentally measured transport properties, it is concluded that the 300 K sheet resistances of very high density 2DEGs at AlN/GaN heterojunctions are currently limited (, 170 , /,) by interface roughness scattering, and can be further reduced by improving the growth conditions. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Evaluation of carrier ampholyte-based capillary electrophoresis for separation of peptides and peptide mimetics,ELECTROPHORESIS, Issue 18 2008an Koval Abstract Carrier ampholyte-based capillary electrophoresis (CABCE) has recently been introduced as an alternative to CE (CZE) in the classical buffers. In this study, isoelectric BGEs were obtained by fractionation of Servalyt pH 4,9 carrier ampholytes to cuts of typical width of 0.2 pH unit. CABCE feasibility was examined on a series of insect oostatic peptides, i.e. proline-rich di- to decapeptides, and phosphinic pseudopeptides , tetrapeptide mimetics synthesized as a mixture of four diastereomers having the ,P(O)(OH),CH2, moiety embedded into the peptide backbone. With identical selectivity, the separation efficiency of CABCE proved to be as good as classical CE for the insect oostatic peptides and better for diastereomers of the phosphinic pseudopeptides. In addition, despite the numerous species present in the narrow pH cuts of carrier ampholytes, CABCE seems to be free of system zones that could hamper the analysis. Peak symmetry was good for moderately to low mobile peptides, whereas some peak distortion due to electromigration dispersion, was observed for short peptides of rather high mobility. [source] Monomeric solution structure of the helicase-binding domain of Escherichia coli DnaG primaseFEBS JOURNAL, Issue 21 2006Xun-Cheng Su DnaG is the primase that lays down RNA primers on single-stranded DNA during bacterial DNA replication. The solution structure of the DnaB-helicase-binding C-terminal domain of Escherichia coli DnaG was determined by NMR spectroscopy at near-neutral pH. The structure is a rare fold that, besides occurring in DnaG C-terminal domains, has been described only for the N-terminal domain of DnaB. The C-terminal helix hairpin present in the DnaG C-terminal domain, however, is either less stable or absent in DnaB, as evidenced by high mobility of the C-terminal 35 residues in a construct comprising residues 1,171. The present structure identifies the previous crystal structure of the E. coli DnaG C-terminal domain as a domain-swapped dimer. It is also significantly different from the NMR structure reported for the corresponding domain of DnaG from the thermophile Bacillus stearothermophilus. NMR experiments showed that the DnaG C-terminal domain does not bind to residues 1,171 of the E. coli DnaB helicase with significant affinity. [source] High-Performance Air-Stable n-Type Organic Transistors Based on Core-Chlorinated Naphthalene Tetracarboxylic DiimidesADVANCED FUNCTIONAL MATERIALS, Issue 13 2010Joon Hak Oh Abstract Core-chlorinated naphthalene tetracarboxylic diimides (NDIs) with fluoroalkyl chains are synthesized and employed for n-channel organic thin-film transistors (OTFTs). Structural analyses of the single crystals and thin films are performed and their charge-transport behavior is investigated in terms of structure,property relationships. NDIs with two chlorine substituents are shown to exhibit a herringbone structure with a very close ,-plane distance (3.3,3.4,Å), a large ,-stack overlap (slipping angle ca. 62°), and high crystal densities (2.046,2.091,g,cm,3). These features result in excellent field-effect mobilities of up to 1.43,cm2,V,1,s,1 with minimal hysteresis and high on,off ratios (ca. 107) in air. This is similar to the highest n-channel mobilities in air reported so far. Despite the repulsive interactions of bulky Cl substituents, tetrachlorinated NDIs adopt a slip-stacked face-to-face packing with an interplanar distance of around 3.4,Å, resulting in a high mobility (up to 0.44,cm2,V,1,s,1). The air-stability of dichlorinated NDIs is superior to that of tetrachlorinated NDIs, despite of their higher LUMO levels. This is closely related to the denser packing of the fluorocarbon chains of dichlorinated NDIs, which serves as a kinetic barrier to the diffusion of ambient oxidants. Interestingly, these NDIs show an optimal performance either on bare SiO2 or on octadecyltrimethoxysilane (OTS)-treated SiO2, depending on the carbon number of the fluoroalkyl chains. Their synthetic simplicity and processing versatility combined with their high performance make these semiconductors highly promising for practical applications in flexible electronics. [source] Carrying capacity and survival strategy for the Pacific bluefin tuna, Thunnus orientalis, in the Western PacificFISHERIES OCEANOGRAPHY, Issue 2 2006YASUO MATSUKAWA Abstract The carrying capacity for the Pacific bluefin tuna at each life stage is estimated and its survival strategy is examined numerically, using a new method to define the hypothetical capacity, the standard population, and the search volumes that are necessary and are feasible for the tuna. The carrying capacity for the adult is estimated at 1,2 × 106 individuals, which corresponds with 5,10% of the hypothetical capacity and is comparable with the maximum levels of the southern and the Atlantic bluefin tuna populations. It is hypothesized semiquantitatively that the migration at each life stage and the remarkable decrement of growth at 120 days and about 40 cm occur as an evolutionary response to population excess over the carrying capacity. It is also hypothesized semiquantitatively that the early larvae have minimal food available in the Subtropical Water and develop the predatory morphology, high growth rate, and high mobility, however, at the expense of a high mortality as an evolutionary response to the tuna spawning in the Subtropical Water. This method may be an available tool to not only investigate the carrying capacity and survival strategy of a specific fish species, but also predict when and in how much abundance the fish species occurs in a specific area of its habitat. [source] High-Performance Phototransistors Based on Organic Microribbons Prepared by a Solution Self-Assembly ProcessADVANCED FUNCTIONAL MATERIALS, Issue 6 2010Yunlong Guo Abstract Oligoarenes as an alternative group of promising semiconductors in organic optoelectronics have attracted much attention. However, high-performance and low-cost opto-electrical devices based on linear asymmetric oligoarenes with nano/microstructures are still rarely studied because of difficulties both in synthesis and high-quality nano/microstructure growth. Here, a novel linear asymmetric oligoarene 6-methyl-anthra[2,3- b]benzo[d]thiophene (Me-ABT) is synthesized and its high-quality microribbons are grown by a solution process. The solution of Me-ABT exhibits a moderate fluorescence quantum yield of 0.34, while the microribbons show a glaucous light emission. Phototransistors based on an individual Me-ABT microribbon prepared by a solution-phase self-assembly process showed a high mobility of 1.66,cm2,V,1 s,1, a large photoresponsivity of 12,000 A W,1, and a photocurrent/dark-current ratio of 6000 even under low light power conditions (30,µW cm,2). The measured photoresponsivity of the devices is much higher than that of inorganic single-crystal silicon thin film transistors. These studies should boost the development of the organic semiconductors with high-quality microstructures for potential application in organic optoelectronics. [source] Hole Injection in a Model Fluorene,Triarylamine CopolymerADVANCED FUNCTIONAL MATERIALS, Issue 2 2009Hon Hang Fong Abstract Recent developments in synthesis and purification have yielded conjugated polymers with hole mobilities exceeding 0.01,cm2 V,1 s,1. Essential to harvesting the potential of these materials in organic light emitting diodes (OLEDs) is the identification of suitable ohmic contacts. Using a model fluorene copolymer that shows high-mobility, non-dispersive hole transport, it is demonstrated that electrodes commonly used as anodes in OLEDs are very poor hole injectors. Injection from Au and indium tin oxide anodes is limited by energy barriers of 0.75 and 0.65,eV, respectively, and the injected current is found to be temperature independent,a prediction that was not reproduced by the leading injection model for disordered organic semiconductors. Injection from a poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonate) (PEDOT:PSS) anode, on the other hand, is found to become less efficient with electric field, a behavior which is currently not understood. In thinner poly[(9,9,-dioctylfluorenyl-2,7-diyl)- co -(4,4,-(N -(4- sec -butyl))diphenylamine)] films, which are of relevance to OLEDs, ohmic losses on the PEDOT:PSS layer are found to limit the flow of current. These results illustrate the opportunity to further improve the performance of OLEDs as well as the challenge posed by high mobility conjugated polymers for the design of hole injection layers. [source] Effects of drought on contrasting insect and plant species in the UK in the mid-1990sGLOBAL ECOLOGY, Issue 1 2002M. D. Morecroft Abstract Aim We examined the effects of drought in the summer of 1995 and the subsequent year on contrasting species of plants, moths, butterflies and ground beetles. We tested whether population increases were associated with: (a) species of warm environments (b) species of dry environments (c) species with rapid reproduction (d) species with high rates of dispersal. Location The study was conducted at Environmental Change Network (ECN) sites throughout Great Britain and Northern Ireland. Methods Climate monitoring, recording of plant species in permanent plots, transect walking for butterflies, light trapping for moths and pitfall trapping for carabid beetles were used. Results There was an overall increase in the number of species recorded in permanent vegetation plots between 1994 and 1996, principally among the annual and biennial vascular plants, probably as a result of gap colonization in grasslands. Most butterfly and moth species increased between 1994 and 1995. Among the butterflies, a southern distribution and high mobility were associated with species tending to increase throughout the period 1994,96, whereas declining species tended to have a northern distribution. A similar number of carabid beetle species increased as decreased in the period 1994,96; decreasing species tended to be associated with lower temperatures and wetter soils. Conclusions Current climate change scenarios indicate that the incidence of droughts in the United Kingdom will increase. A series of dry, hot summers could lead to a rapid change in the population of some species although others, including many plants, may be more resilient. This may lead to complex changes in ecosystems and needs to be considered in planning conservation strategies. [source] Mobile locations: construction of home in a group of mobile transnational professionalsGLOBAL NETWORKS, Issue 1 2007MAGDALENA NOWICKA Abstract How do professionals constitute their homes under conditions of extensive mobility? The study is based on interviews with professionals working for an international organization who are chronically mobile. Despite their high mobility, they describe little difficulty constructing homes. Home can best be understood here not as a fixed location, but as a set of relationships, to both humans and non-humans. There are elements of spatial proximity, but also of distance, and homes may be defined by both objects present and excluded. They may be a focal point, but at the same time part of a heterogeneous network that spans localities as well as binds past and present. Home is therefore territorially defined, but only as an extended network rather than as a bounded location. [source] Microstructural Origin of High Mobility in High-Performance Poly(thieno-thiophene) Thin-Film TransistorsADVANCED MATERIALS, Issue 6 2010Chenchen Wang High-mobility PBTTT thin-film transistors are modeled with a mobility edge model and compared with P3HT. Their improved performance is not due to a low trap density but rather due to high mobility in the crystallites. Characterization of delaminated films with transmission electron microscopy and atomic force microscopy indicates terraces that are composed of nanometer-scale features (see figure). [source] Encapsulated-Dye All-Organic Charged Colored Ink Nanoparticles for Electrophoretic Image DisplayADVANCED MATERIALS, Issue 48 2009Sun Wha Oh Electrophoretic ink nanoparticles with high mobility are successfully fabricated by dispersion polymerization. The color of test cells can be changed by applying a bias voltage, as shown in the figure: the lower row shows the same cells as the upper row but with an applied voltage. These all-organic, encapsulated-dye, electrophoretic ink particles are expected to reduce the fabrication cost of e-ink in electrophoretic image display cells. [source] Assembly of Nanoscale Organic Single-Crystal Cross-Wire CircuitsADVANCED MATERIALS, Issue 42 2009Qingxin Tang Organic single-crystal transistors and circuits can be assembled by nanomechanical manipulation of nanowires of CuPc, F16CuPc, and SnO2:Sb. The crossed bar devices have low operational voltage, high mobility and are stable in air. They can be combined into circuits, providing varied functions including inverters and NOR and NAND logic gates, opening new opportunities for organic nanoelectronics and highly sophisticated integrated logic devices. [source] High-Mobility Nonvolatile Memory Thin-Film Transistors with a Ferroelectric Polymer Interfacing ZnO and Pentacene ChannelsADVANCED MATERIALS, Issue 42 2009Kwang H. Lee Nonvolatile memory ferroelectric thin-film transistors (FeTFT) with P(VDF-TrFE) polymer are demonstrated with both n-channel ZnO and p-channel pentacene. A high mobility of ,1,cm2 V,1 s,1 and large memory window of ,20,V are achieved through the organic ferroelectric, inorganic channel hybrid device of ZnO-FeTFT. WRITE/ERASE states are clearly distinguished by ±20,V switching for ZnO- and pentacene-FeTFTs. [source] Evaluation of ferromagnetic shape-memory alloys by the extended Hückel methodIEEJ TRANSACTIONS ON ELECTRICAL AND ELECTRONIC ENGINEERING, Issue 3 2007Kei Ehara Student Member Abstract Ferromagnetic shape-memory alloy (SMA) are powerful candidates as actuators, pressure sensors, magnetic sensors, etc. Magnetic-field-induced strain has been observed in many ferromagnetic SMA. The magnetic-field-induced strain is a reversible transformation in the martensite phase with the magnetic field. We have investigated the property of the ferromagnetic shape-memory materials by the extended Hückel method, and estimated the ferromagnetic shape-memory of Fe,Pt and Fe,Pd alloys at high temperatures. We used two physical quantities, i.e. cohesive energy and energy fluctuation, to measure the stability of the materials. On the basis of the cohesive energy and energy fluctuation, we discuss the characteristics of ferromagnetic SMA, in which the energy fluctuation is a measure of thermal stability of the metals and/or alloys. The martensite structure is unstable, which means that the energy fluctuation has to be controlled to a small value to keep the martensite phase. Furthermore, it is estimated that the energy fluctuation is associated with the Curie temperature. The Curie temperature is an essential parameter for ferromagnetic materials. From the discussion presented above, we can propose the following: (i) Alloys possessing a low cohesive energy are associated with a high mobility of atoms and are suitable for ferromagnetic shape-memory materials; (ii) Alloys showing a low energy fluctuation show ferromagnetic shape-memory and are favored for use as memory devices. We found that I (iodine) is the best dopant for Fe,Pt ferromagnetic SMA, and Tc (technetium) is the best dopant for Fe,Pd ferromagnetic SMA. Copyright © 2007 Institute of Electrical Engineers of Japan© 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [source] A New Poly(thienylenevinylene) Derivative with High Mobility and Oxidative Stability for Organic Thin-Film Transistors and Solar CellsADVANCED MATERIALS, Issue 27 2009Bogyu Lim A novel thiophene-thienylenevinylene copolymer is synthesized and evaluated for use in organic field-effect transistors and organic solar cells. PETV12T shows good solution processability and high structural organization after annealing. Organic thin-film transistors based on the polymer exhibit high mobility and a high resistance to oxidation. In addition, PETV12T shows potential as an electron donor in bulk heterojunction solar cells. [source] Processed kaolin as an alternative insecticide against the European pear sucker, Cacopsylla pyri (L.)JOURNAL OF APPLIED ENTOMOLOGY, Issue 7 2005C. Daniel Abstract:, Application of processed kaolin particle film (Surround® WP; Engelhard Corporation, Iselin, NJ, USA) repels insects without lethal effects; hence side effects on beneficial arthropods are low. Processed kaolin may be an alternative to broad-spectrum insecticides used against European pear sucker, Cacopsylla pyri (L.), in organic and conventional pear production. A small-plot field trial was conducted in spring 2003 to assess this hypothesis. Multiple applications of processed kaolin during the first flying period of C. pyri significantly reduced the number of nymphs compared to the untreated control. Processed kaolin protected pear trees at least as good as the standard organic insecticide rotenone. Since the effects on the summer population could not be assessed in this small-plot trial due to the high mobility of the adult C. pyri, a large-plot trial was conducted in 2004. Thereby, the processed kaolin showed a very high efficacy and the population of C. pyri was kept under a damaging level over the whole season. At the end of June the population density of C. pyri in the processed kaolin treated area was lower than in the IPM treated plot. In conclusion, kaolin shows promise as an alternative control for C. pyri in organic and IPM orchards. [source] Magnebike: A magnetic wheeled robot with high mobility for inspecting complex-shaped structuresJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 5 2009Fabien Tâche This paper describes the Magnebike robot, a compact robot with two magnetic wheels in a motorbike arrangement, which is intended for inspecting the inner casing of ferromagnetic pipes with complex-shaped structures. The locomotion concept is based on an adapted magnetic wheel unit integrating two lateral lever arms. These arms allow for slight lifting off the wheel in order to locally decrease the magnetic attraction force when passing concave edges, as well as laterally stabilizing the wheel unit. The robot has the main advantage of being compact (180 × 130 × 220 mm) and mechanically simple: it features only five active degrees of freedom (two driven wheels each equipped with an active lifter stabilizer and one steering unit). The paper presents in detail design and implementation issues that are specific to magnetic wheeled robots. Low-level control functionalities are addressed because they are necessary to control the active system. The paper also focuses on characterizing and analyzing the implemented robot. The high mobility is shown through experimental results: the robot not only can climb vertical walls and follow circumferential paths inside pipe structures but it is also able to pass complex combinations of 90-deg convex and concave ferromagnetic obstacles with almost any inclination regarding gravity. It requires only limited space to maneuver because turning on the spot around the rear wheel is possible. This high mobility enables the robot to access any location in the specified environment. Finally the paper analyzes the maximum payload for different types of environment complexities because this is a key feature for climbing robots and provides a security factor about the risk of falling and slipping. © 2009 Wiley Periodicals, Inc. [source] Wide-ranging molecular mobilities of water in active pharmaceutical ingredient (API) hydrates as determined by NMR relaxation timesJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2008Sumie Yoshioka Abstract In order to examine the possibility of determining the molecular mobility of hydration water in active pharmaceutical ingredient (API) hydrates by NMR relaxation measurement, spin,spin relaxation and spin,lattice relaxation were measured for the 11 API hydrates listed in the Japanese Pharmacopeia using pulsed 1H-NMR. For hydration water that has relatively high mobility and shows Lorentzian decay, molecular mobility as determined by spin,spin relaxation time (T2) was correlated with ease of evaporation under both nonisothermal and isothermal conditions, as determined by DSC and water vapor sorption isotherm analysis, respectively. Thus, T2 may be considered a useful parameter which indicates the molecular mobility of hydration water. In contrast, for hydration water that has low mobility and shows Gaussian decay, T2 was found not to correlate with ease of evaporation under nonisothermal conditions, which suggests that in this case, the molecular mobility of hydration water was too low to be determined by T2. A wide range of water mobilities was found among API hydrates, from low mobility that could not be evaluated by NMR relaxation time, such as that of the water molecules in pipemidic acid hydrate, to high mobility that could be evaluated by this method, such as that of the water molecules in ceftazidime hydrate. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:4258,4268, 2008 [source] Orientation and Dynamics of ZnO Nanorod Liquid Crystals in Electric FieldsMACROMOLECULAR RAPID COMMUNICATIONS, Issue 12 2010Matthias Zorn Abstract ZnO nanorod polymer hybrids (i.e., ZnO nanorods coated with a block copolymer with a short anchor block (dopamine) and a longer solubilizing block of polystyrene (PS)) form liquid crystalline (LC) phases if they are dispersed at high concentration e.g., in a PS oligomer matrix. Due to the high mobility of the low Tg -matrix the nanorod polymer hybrids show a switching behavior under an applied AC electric field. Hence, the orientation of the nanorod mesogens can be changed from planar (parallel to the substrate) to homeotropic (perpendicular) in full analogy to the switching of low molecular liquid crystals in an electric field. Dielectric measurements show that such a switching is mainly due to the cooperative LC behavior, because the rods themselves exhibit only a very small effective dipole moment. The process can be investigated by polarizing microscopy. SEM images show the orientations of the individual nanorods, which correspond to the Fredericks transition well known for liquid crystals aligned in an electric field. This was the first time such a transition could be visualized by electron microscopy due to the large nanorod mesogens. The observation is interesting to orient nanorods perpendicular to an electrode and can help to improve optoelectronic devices. [source] | |||||||||||||||||||||||||