Photoinduced Colossal Magnetoresistance under Substantially Reduced Magnetic Field

The colossal magnetoresistive insulator to metal switching of almost nine orders of magnitude under the significantly reduced magnetic field is achieved by illumination for the low bandwidth manganite thin films. Similarly, by changing the measuring bias voltage through the sample the required magnetic field for insulator–metal transition can be further fine‐tuned. By applying a magnetic field of suitable strength, the samples can also be tuned to be extra sensitive to the illumination having colossal effect on the resistivity at low temperatures. This kind of utilizing of multiple external stimulants, which together change the properties of the material, could have significant impact on the new generation of phase‐change memories working under affordable conditions.     

Measuring resistivity of silicon nanowire using pseudo-random binary sequence injection

Nanostructures can show mechanical and electrical properties that differ from their bulk forms, and thus, precise experimental evaluation is needed when the structures are used in nanoelectronic devices or nanoelectromechanical systems. Ohm?s law does not apply for nanostructures due to the various effects of size. It has been shown that due to surface scattering, the resistivity of the wire increases when the size decreases. This paper extends the studies and investigates how the resistive characteristics vary as the wire is stretched. An electrostatic actuating tensile device is applied and the resistive characteristics are evaluated in the frequency domain by means of maximum-length pseudo-random binary sequence (MLBS). The results reveal unreported characteristics of the applied nanowire; the resistance is increased as a function of stretching force.     

Reliability analysis of a glulam beam

The present case study is an example of the use of reliability analysis to asses the failure probability of a tapered glulam beam. This beam is part of a true structure built for a super market in the town of Kokemäki in Finland. The reliability analysis is carried out using the snow load statistics available from the site and on material strength information available from previous experiments. The Eurocode 5 and the Finnish building code are used as the deterministic methods to which the probabilistic method is compared to. The calculations show that the effect of the strength variation is not significant, when the coefficient of variation of the strength is around 15% as usually assumed for glulam. The probability of failure resulting from a deterministic design based on Eurocode 5 is low compared to the target values and lower sections are possible if applying a probabilistic design method. In fire design, if a 60 min resistance is required, this is not the case according to Eurocode 5 design procedures, a higher section would be required. However, a probabilistic based fire analysis results in bounds for the yearly probability of failure which are comparable to the target value and to the values obtained from the normal probabilistic based design.     

Applications of UV-nanoimprint soft stamps in fabrication of single-frequency diode lasers

We show how to use a modified poly-dimethyl-siloxane (PDMS) soft stamp to reduce pattern deformation and residual layer thickness in soft UV-nanoimprint lithography. A soft stamp thinned with toluene reduces the residual layer of a resist by as much as 50% compared to an unthinned stamp. We apply the soft UV-nanoimprint to prepare nanopatterned waveguides for a single-frequency diode laser. This laser operates with a side-mode suppression ratio of 50 dB, which indicates that the patterns are precise and uniform over the whole imprint field. To the best of our knowledge, this is the first single-frequency laser fabricated by soft UV-nanoimprint technology.     

Synthesis and characterization of poly(2-hydroxyethyl methacrylate/itaconic acid) copolymeric hydrogels

In the present study poly(2-hydroxyethyl methacrylate-co-itaconic acid) (P(HEMA/IA)) hydrogels were synthesized by free-radical copolymerization of 2-hydroxyethyl methacrylate and itaconic acid in order to evaluate as controlled release drug delivery system. All polymerizations were performed in a mixture of water/ethanol with ethylene glycol dimethacrylate, as crosslinking agent, potassium persulfate, as initiator, and N, N, N′, N′-tetramethylethylene diamine, as activator. The samples were characterized by FTIR and SEM. Swelling kinetics and antibiotic release studies were performed using gravimetry and UV spectrophotometry, respectively. The antibacterial activity studies were performed bearing in mind that infections are the most common cause of biomaterial implant failure and represent a constant menace to the application of medical implants. The hemocompatibility testing was performed as imperative for medical devices intended for direct or indirect blood exposure. In accordance with the results of antibacterial assessment on gels loaded with antibiotics and hemolytic activity testing these gels exerted good bacterial growth inhibition and favorable hemolytic activity. The release profiles of antibiotics, evaluated in vitro conditions, were correspondent for antibacterial therapeutics. Therefore, it was concluded that (P(HEMA/IA)) gels could be propound for the potential application as drug delivery systems for the controlled release of antibiotics.     

具备颜色管理功能的发光二极管驱动器:前景一片璀璨

简介 越来越多移动电话、便携式媒体播放机、电子游戏机以及导航系统等便携式电子消费产品采用彩色发光二级管.     

Using fleets of electric-drive vehicles for grid support

Electric-drive vehicles can provide power to the electric grid when they are parked (vehicle-to-grid power). We evaluated the economic potential of two utility-owned fleets of battery-electric vehicles to provide power for a specific electricity market, regulation, in four US regional regulation services markets. The two battery-electric fleet cases are: (a) 100 Th!nk City vehicle and (b) 252 Toyota RAV4. Important variables are: (a) the market value of regulation services, (b) the power capacity (kW) of the electrical connections and wiring, and (c) the energy capacity (kWh) of the vehicle's battery. With a few exceptions when the annual market value of regulation was low, we find that vehicle-to-grid power for regulation services is profitable across all four markets analyzed. Assuming now more than current Level 2 charging infrastructure (6.6 kW) the annual net profit for the Th!nk City fleet is from US$ 7000 to 70,000 providing regulation down only. For the RAV4 fleet the annual net profit ranges from US$ 24,000 to 260,000 providing regulation down and up. Vehicle-to-grid power could provide a significant revenue stream that would improve the economics of grid-connected electric-drive vehicles and further encourage their adoption. It would also improve the stability of the electrical grid.     

Transformation of oil-producing fungus, Mortierella alpina 1S-4, using Zeocin, and application to arachidonic acid production

The arachidonic acid-producing fungus Mortierella alpina 1S-4, an industrial strain, was endowed with Zeocin resistance by integration of the Zeocin-resistance gene at the rDNA locus of genomic DNA. Plasmid DNA was introduced into spores by microprojectile bombardment. Twenty mg/ml Zeocin completely inhibited the germination of M. alpina 1S-4 spores, and decreased the growth rate of fungal filaments to some extent. It was suggested that preincubation period and temperature had a great influence on transformation efficiency. Four out of 26 isolated transformants were selected. Molecular analysis of these stable transformants showed that the plasmid DNA was integrated into the rDNA locus of the genomic DNA. We expect that this system will be applied for useful oil production by gene manipulation of M. alpina 1S-4 and its derivative mutants. On the basis of the fundamental transformation system, we also tried to overexpress a homologous polyunsaturated fatty acid elongase gene, which has been reported to be included in the rate-limiting step for arachidonic acid production, thereby leading to increased arachidonic acid production.     

Crystallinity of polyamide 6 staple fibers in the felt structure under simulated paper machine conditions

Polyamide 6 (PA6) is used in staple fibers and yarns in paper machine press felts due to its good mechanical properties. The crystalline modifications (α and γ forms) and the degree of crystallinity of PA6 can change under stress (compression) and heat (friction), which are present during mechanical dewatering (nip). Here, we investigate the effects of the molecular weight and crystallinity of a polymer on the mechanical properties of PA6 staple fibers such as wear resistance and compaction. The experimental part involves the ageing of felt specimens in a wet pressing simulator. The properties of the felt (air permeability), and the durability and branching of the staple fiber are examined as functions of the wear of a press felt and the crystallinity of the polymer. The changes that take place in the PA6 polymer are investigated using several techniques, and their connection with the properties of a new or aged press felt is discussed. The results indicate that the increase in molecular weight has a beneficial effect on the material's mechanical properties, and our observations also support previous studies on the crystallinity and branching of PA6. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Self-aligned patterning method of poly(aniline) for organic field-effect transistor gate electrode

We present a new manufacturing method for the bottom-gate type organic field-effect transistor (OFET) having a self-aligned gate electrode based on conducting poly(aniline). This method utilizes the possibility to turn the insulating emeraldine base (PANI-EB) form of poly(aniline) into the conducting emeraldine salt (PANI-ES) form by using UV exposure and photoacid generator (PAG) material. When the source–drain electrodes are used as the mask layer in the UV exposure step an optimal alignment between the gate electrode and source–drain electrodes can be reached, and the parasitic capacitance of the transistor can be minimized. We anticipate that the proposed concept also simplifies the fabrication of the transistors since no additional processing of the photoresist layers is needed to pattern the gate electrode or the gate insulator layer.