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  • 2005-2009  (8)
  • 1
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advances in science and technology Vol. 54 (Sept. 2008), p. 180-186 
    ISSN: 1662-0356
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Natural Sciences in General , Technology
    Notes: We report on tailoring magnetic properties and giant magneto-impedance GMI in glasscoatedmicrowires fabricated by the Taylor-Ulitovsky method, by means of selection of their alloycomposition and/or annealing conditions. Fe-rich microwires subjected to stress annealing show thehysteresis loops of inclined form due to induced transverse magnetic anisotropy, and hence becomesuitable for GMI. The transverse anisotropy depends on the annealing conditions: temperature,duration and stress. The application of external stress further drastically changes the shape of thehysteresis loops and the GMI spectra. The wires with compositions Co-Fe-Ni-Si-B and Co-Fe-Cr-Si-B are demonstrated to have a low Curie temperature (below 90oC) and pronounced temperaturedependentmagnetic properties and GMI effect. Both families of developed microwires are foreseenfor applications in high performance stress and temperature sensors as well as in tuneable sensorycomposite materials. Such composites contain short pieces of microwires embedded into adielectric matrix and contribute to the effective ac permittivity. The latter depends on the wiremagnetic properties through the GMI effect and can be tailored to produce a microwave responsesensitive to environment: magnetic field, stress and temperature
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 47-50 (June 2008), p. 113-116 
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this work we present the influence of different particle size (surface areas: 120,150, 200 and 250m2/g) and size distribution of precipitated silica on the mechanical properties of Ethylene-Propylene-Diene (EPDM) rubber. The vulcanization system employed was efficient. Compoundswere prepared using a Banbury internal mixer. Tensile and tear properties of vulcanized blendswere determined according to ASTM D412 and ASTM D624 procedures, respectively. Resultsshow an increasing tendency on tensile properties when particle size decreases, due to the betterdispersion of the filler and to a greater interaction with the rubber. Increases of up to 500% ontensile strength and 400% on tear strength were observed. However, there was an incoherentbehavior for the silica with surface area of 200 m2/g (Si-200), so size distribution of the aggregateswas experimentally determined by a microphotography study. Secondary aggregates sizedistribution was very different for each type of silica. Aggregates for Si-200 presented a bimodaldistribution where the greater frequencies correspond to aggregates with surface area higher thanthe corresponding values for the Si-120. This fact could explain why the mechanical properties ofthe EPDM filled with Si-200 are not in between the values of the compounds filled with Si-150 andSi-250
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advances in science and technology Vol. 54 (Sept. 2008), p. 29-40 
    ISSN: 1662-0356
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Natural Sciences in General , Technology
    Notes: The discovery of the magnetoimpedance (MI) effect in 1994 had a strongimpact on the development of magnetic sensors, offering miniature, highly sensitive, andquick response elements. Along with traditional areas of sensing applications (data storage,bio-medical electronics, robotics and security), the MI elements have a high potential fornon-destructive testing (as eddy current probes) and smart sensory systems (self-sensingcomposites). In certain soft magnetic materials, such as composites of amorphous thin wires,the impedance change (MI ratio) can be as high as 600 % in the MHz band and 50-100% atGHz frequencies subjected to small magnetic fields or stresses. Furthermore, special thin-filmstructures have been proposed to improve the MI performance in miniature elements. Thispaper discusses physical concepts of MI in multilayered structures including MI ratioenhancement and effect of anisotropy, experimental results proving high sensitivity to theexternal stimuli for excitation frequencies up to few GHz, practical sensor designs and,finally, the use of MI fibers for tagging the composites to build-in sensing functionality
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advances in science and technology Vol. 54 (Sept. 2008), p. 201-210 
    ISSN: 1662-0356
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Natural Sciences in General , Technology
    Notes: New types of stress sensitive and magnetic field tunable microwave compositematerials are discussed where embedded short ferromagnetic microwire inclusions are used ascontrollable radiative elements. The dc external magnetic field is applied to the whole compositestructure. And, the local stress is transferred to the individual microwires through theaccommodating composite matrix. The spatial and angular distributions of microwires can berandom, partly ordered, or completely ordered. For a wide frequency range, the free-spacemicrowave response of a wire-filled composite can be characterized by a complex effectivepermittivity with resonance frequency dispersion. The latter depends on the conductive andmagnetic properties of the microwire inclusions that contribute to the ac microwiremagnetoimpedance (MI). In the vicinity of the so-called antenna resonance frequency, which isdefined by the length of microwires and matrix dielectric constant, any variations in the MI of themicrowires will result in large changes of the effective permittivity, and hence the reflection andtransmission coefficients for an incident microwave. The field or stress dependence of the effectivepermittivity arises from the corresponding field or stress sensitivity of the MI in the ferromagneticmicrowires with induced circumferential or helical magnetic anisotropy, respectively. The strongfield tunable effect in the proposed composite materials can be utilized to introduce reconfigurablemicrowave properties in coatings, absorbers, and randomizers, and also in new media such asmicrowave metamaterials and bandgap wire structures. A maximum field tunability of 30 dB wasachieved for free-space transmission measurements when the external magnetic field changed fromzero to ~40 Oe. The stress sensitivity of reflection and transmission coefficients opens up newpossibilities for the distant non-destructive testing and evaluation of composite materials both in thelaboratory environment and large scale applications. The stress tunability of transmissioncoefficient may reach up to 5-8 dB within the elastic limit. The reflection coefficient usuallydemonstrates less tunability in both cases (field and stress dependent) and may require a multilayerstructure to achieve better results, but it is always strong enough for the stress sensing applications
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 47-50 (June 2008), p. 278-281 
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this paper, effort has been undertaken to study the fracture behavior ofthermoplastic/elastomer (PP/SBS) dynamically vulcanized blends by analyzing the EWF testresults. PP/SBS blends were prepared with concentrations of SBS of 15, 30 and 40 wt%. Deeplydouble edged notched tension (DDENT) specimens were cut from injection molded plaques forfracture testing. It should be noted that the incorporation of SBS to PP seems to enhance fracturetoughness, thus the specific essential work (we) increases with elastomer content. The elastomerparticles contribute to the energy dissipation at the fracture surface and in the outer plastic zone inwhich various types of deformation might have been at work. Also, it seems that the fracturetoughness value levels-off from 30 wt% rubber on. In addition, the incorporation of SBS triggers aconsiderable plastic deformation, since the non-essential work ( βwp) increases compared to thevalue of pure PP. Nonetheless, a decrease in βwp is present with increasing amount of rubber. Sothe EWF method revealed that the dynamic vulcanization method can impair fracture resistance toPP/SBS blends
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Clinical and experimental dermatology 30 (2005), S. 0 
    ISSN: 1365-2230
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Bullous pemphigoid (BP) is an autoimmune blistering skin disease associated with circulating autoantibodies to the hemidesmosomal antigens BP180 and BP230. We report two cases of therapy-refractory BP adjuvantly treated by tryptophan immunoadsorption. In both patients, this treatment was associated with rapid clinical improvement and reduction in the required corticosteroid dosage. In addition, levels of circulating anti-BP180 autoantibodies decreased markedly. Antibodies that were eluted from the tryptophan matrix bound to BP180 and induced dermal–epidermal separation in cryosections of human skin. Our observations suggest that immunoadsorption may be a helpful adjuvant treatment in severe BP.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background:  A randomized double-blind, placebo-controlled study was conducted in patients allergic asthma sensitized to Dermatophagoides pteronyssinus.Objective:  To evaluate the efficacy and safety after 1-year of immunotherapy with a modified D. pteronyssinus extract compared with placebo.Material and methods:  Fifty-five patients were randomly allocated to receive the active treatment (n = 29), or placebo (n = 26). The main outcome was the specific bronchial provocation test (BPT). Other parameters analysed were dose–response skin prick test (SPT), symptom and medication scores and asthma quality of life (AQLQ).Results:  At the end of the study, the active group showed a significant increase in the PD20FEV1 compared with placebo (P = 0.0029). Nineteen patients of the active vs 10 of the placebo group needed more than twice the initial amount of allergen extract to have a positive BPT (P = 0.0293); seven patients in the placebo vs one in the active group needed less than half (P = 0.0137). In SPT, a significant improvement (P = 0.0049) was found in the active group. This group also had a median reduction of 91.5% in symptom scores, whereas the placebo group increased by 86%. Medication scores decreased in both groups (56% in the active and 11.4% in the placebo). In AQLQ, the differences between both groups were significant (P = 0.0234) at the end of the study.Conclusion:  After 1 year of treatment, the modified extract of D. pteronyssinus demonstrated to be safe and efficacious to treat patients with asthma and allergic rhinoconjunctivitis sensitized to this mite.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Glass coated microwires with two metallic nucleus compositions Co57Fe 6.1Ni10B15.9Si11 and Fe36,4Co41,7B11,8Si10,1 with 3 different glass coating compositions (Pyrex – 74.5% SiO2, 15% - B2O3, 3%- Na2O, 2%- Al2O3 1.5% -K2O; Nonex – 73% SiO2, 16.5% - B2O3, 6% - PbO 3 %-Na2O, 1.5% -K2O;and F1 – 70.2% SiO2, 27% - B2O3, 0.8 %-Na2O, 2%- LiO2 1% -K2O;) with very similar geometry (metallic nucleus diameter 7 µm, total diameter 19 µm) have been successfully fabricated and studied. Ferich microwires in as-prepared state show rectangular hysteresis loops, which is connected with the strong internal stresses induced by the fabrication process. Co-rich compositions show inclined hysteresis loop with smaller value of coercive field. The coercivity, Hc, of Co-rich microwires is the highest and of Ferich samples is the lowest in the case of Pyrex coated microwires. The Nonex coated microwires are in the intermediate position while the F1 coated Co-rich microwires have the lowest Hc while the Fe-rich samples have the highest Hc. The mechanical tests show that the best tensile strain yield is observed in samples coated by Nonex glass followed by Pyrex and F1. In this way the variation of the glass coating material allows to tailor both magnetic and mechanical properties of glass coated tiny microwires
    Type of Medium: Electronic Resource
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