► Systematic studies of the optimization of magnetic properties and GMI effect of microwires. ► Systematic study of the effect of magnetoelastic anisotropy on magnetic properties of microwires. ► ...Contextual discussions of the impact of magnetoelastic anisotropy on GMI effect of microwires. ► Systematic study of effect of magnetostatic interactions on magnetic properties of microwires. ►Contextual discussions of magnetic microwires applications for magnetic microsensors.
We present the results on tailoring of soft magnetic properties and GMI effect in thin microwires paying special attention on achievement of low hysteretic high GMI effect in the extended frequency range (up to 4GHz). We observed considerable dependence of the GMI ratio and magnetic anisotropy field, Hk, of Co-rich amorphous microwires with vanishing magnetostriction constant on the internal and applied stresses. For low magnetostrictive Co-rich composition we obtained microwires low coercivity values (generally below 10A/m). Field dependence of the off-diagonal voltage response measured in pulsed regime (pulsed GMI) exhibits anti-symmetrical shape.
The magnetic anisotropy of Co and Fe-rich microwires can be tailored by stress or magnetic field annealing. Particularly stress annealed Fe-rich microwires exhibit stress-sensitive GMI effect and hysteretic properties. Varying the time and the temperature of such stress annealing we are able to tailor both magnetic properties and GMI. Additionally, magnetic response of linear microwires arrays and GMI effect of the system containing few microwires can be tailored through the magnetostatic interaction between the microwires.
We found, that if the surface anisotropy is not circumferential, then the MI curve Z(H) presents hysteresis. This hysteresis can be suppressed by application of sufficiently high DC bias current IB that creates a circumferential bias field HB.
We present an overview of the factors as well as post processing tools allowing optimization of magnetic softness and GMI effect of rapidly quenched materials: microwires and ribbons. Generally, low ...coercivity and high GMI effect have been observed in as-prepared Co-rich compositions. Annealing at adequate conditions can be very effective for manipulation of the magnetic properties and GMI effect of amorphous and nanocrystalline rapidly quenched materials. After annealing of Co-rich compositions, we can observe transformation of inclined hysteresis loops to rectangular. However, at certain annealing conditions GMI effect can be improved. Using stress-annealing, GMI effect of both Fe-rich and Co-rich microwires as well as of amorphous ribbons can be improved. On the other hand, in Fe-rich FeCuNbSiB microwires after appropriate annealing we observed considerable magnetic softening and GMI effect enhancement. The other promising post-processing allowing GMI effect optimization is Joule heating.
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•Trends in optimization of GMI effect in amorphous and nanocrystalline materials.•Magnetic softening of Fe-rich microwires after stress-annealing or nanocrystallization.•Improvement of GMI effect after Joule heating of Co-rich microwires.•Optimization of GMI effect after post-processing of Co-rich amorphous ribbons.•Improvement of GMI effect after annealing and stress-annealing of Co-rich microwires.
We studied the correlation between magnetic softness and magnetostriction coefficient for as-prepared and annealed Co–Fe-rich microwires. We found that the hysteresis loops and magnetostriction ...coefficients of Co and Fe-rich microwires depend not only on the chemical composition of the metal but also on internal stress. Consequently, both hysteresis loop and magnetostriction coefficient can be adjusted by annealing. We varied the time and temperature of annealing and observed changes of the character of the hysteresis loops. These changes correlated with evolution of the magnetostriction coefficient. Drastic changes of the hysteresis loop for Co-rich microwires were attributed to changes of the sign and value of the magnetostriction coefficient.
Cancer is a leading cause of mortality globally. Despite remarkable improvements in cancer-treatment approaches, disease recurrence and progression remain major obstacles to therapy. While ...chemotherapy is still a first-line treatment for a variety of cancers, the focus has shifted to the development and application of new approaches to therapy. Nevertheless, the relationship between immune response, neoplastic diseases and treatment efficiency is not fully understood. Therefore, the aim of the study was to investigate the immunopharmacological effects of methacrylic acid homopolymer in an in vivo tumor model. Materials and methods: Monomeric methacrylic acid was used to synthesize polymers. Methacrylic acid was polymerized in dioxane in the presence of 4-Cyano-4-(dodecylsulfanylthiocarbonyl)sulfanylpentanoic acid. To study the molecular weight characteristics of PMAA by GPC, carboxyl groups were preliminarily methylated with diazomethane. An experimental cancer model was obtained by grafting RMK1 breast cancer cells. The serum levels of IL-6, IL-10, IL-17, transforming growth factor β1 (TGF-β1), and tumor necrosis factor α (TNF-α) were measured by ELISA. Results: The effect of PMAA on the serum concentrations of several cytokines was studied upon its single administration to laboratory animals in early neoplastic process. The IL-6, IL-17 and TGF-β1 concentrations were found to change significantly and reach the level observed in intact rats. The IL-10 concentration tended to normalize. Conclusion: The positive results obtained are the basis for further studies on the effect of methacrylic-acid polymers with different molecular-weight characteristics on the neoplastic process.
As-prepared and annealed Heusler-type NiMnGa glass-covered microwires present considerable dependence of magnetization on magnetic field values attributed to the magnetic and atomic disorder. We ...observed that annealing conditions strongly affect structure, temperature dependence of magnetization and Curie temperature of microwires. After annealing a magnetic phase transition is observed at about 270–300 K which is beneficial for magnetic solid state refrigeration. Exchange bias effect, enhanced coercivity values at low temperature and features that can be attributed to coexistence of two magnetic phases are observed after long annealing of NiMnGa glass-covered microwires.
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•Tunability of magnetic properties of Heusler-type microwires by annealing.•Magnetic phase transition near room temperature beneficial for magnetic solid state refrigeration.•An exchange bias of about 20 Oe at 5 K in annealed NiMnGa microwires.•An enhanced coercivity at low temperatures in annealed NiMnGa microwires.
Saliva is one of the most significant biological liquids for the development of a simple, rapid, and non-invasive biosensor for training load diagnostics. There is an opinion that enzymatic bioassays ...are more relevant in terms of biology. The present paper is aimed at investigating the effects of saliva samples, upon altering the lactate content, on the activity of a multi-enzyme, namely lactate dehydrogenase + NAD(P)H:FMN-oxidoreductase + luciferase (LDH + Red + Luc). Optimal enzymes and their substrate composition of the proposed multi-enzyme system were chosen. During the tests of the lactate dependence, the enzymatic bioassay showed good linearity to lactate in the range from 0.05 mM to 0.25 mM. The activity of the LDH + Red + Luc enzyme system was tested in the presence of 20 saliva samples taken from students whose lactate levels were compared by the Barker and Summerson colorimetric method. The results showed a good correlation. The proposed LDH + Red + Luc enzyme system could be a useful, competitive, and non-invasive tool for correct and rapid monitoring of lactate in saliva. This enzyme-based bioassay is easy to use, rapid, and has the potential to deliver point-of-care diagnostics in a cost-effective manner.
New copolyfluorenes containing 4,7-di-2-thienyl-2,1,3-benzothiadiazole and 2,1,3-benzothiadiazole or derivatives of naphthalimide as luminophores were synthesized under microwave heating. ...Charge-transporting carbazole, triphenylamine, or diphenyloxadiazole groups were introduced into the side chains of polymers through 9,9-bis-(4-phenoxy)-2,7-fluorene units. Copolyfluorenes were also modified via insertion of 10 mol% of 2,7-9,9-bis-(6′-diethoxyphosphorylhexyl)fluorene or dibenzothiophene-S,S-dioxide comonomer units into the polymer backbone. This study demonstrates the influence of chemical compositions, molecular masses of the polymers under investigation, and thermal treatment on microstructures of their films. Photo- and electroluminescent characteristics of the synthesized copolyfluorenes were determined. The best samples of devices manifested the luminance of 5110 cd m⁻2, the current efficiency of 1.33 cd A⁻1, and the CIE 1931 xy chromaticity coordinates of (0.339 0.364), or 7930 cd m⁻2, 2.18 cd A⁻1, and of (0.300 0.369) respectively. The effect of active layer thickness on the white emission color of polymer light-emitting diodes was revealed.
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•Light-emitted copolyfluorenes were obtained by microwave synthesis with Suzuki method.•Copolyfluorene structure modified by green, conducting and polar groups in side chain.•Film morphology depends on structural units, molecular mass and temperature treatment.•Embedding end-groups affect films' morphology and their photophysical properties.•Polar groups interact with donor-acceptor units and allow getting PLED white emission.
•Stress-annealing induces length distribution of helical magnetic structure in microwire.•Reason of helical length distribution is distribution of magnetic anisotropy.•Length distribution of ...helicality of magnetic structure in microwire is controlled by torsion stress.
We report the stress-annealing induced distribution of the helical magnetic structure in the magnetic microwires. The longitudinal space distribution of the magnetic anisotropy originated by stress-annealing at variable annealing temperature is the reason of the observed effect. We have found that the helicality of magnetic structure in different points of the microwire could be controlled by the external mechanical torsion stress.
•Remarkable improvement of GMI effect in Joule heatedCo -rich microwires.•Interpretation of the GMI effect improvement considering circumferential magnetic field associated to Joule heating.•Superior ...GMI ratio of Joule heated microwire in the frequency range up to 400 MHz.
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The effect of Joule-heating on hysteresis loops and giant magnetoimpedance effect, GMI; of Co69.2Fe3.6Ni1B12.5Si11Mo1.5C1.2 glass-coated microwire is studied. Joule heating performed at suitable conditions prevents the magnetic hardening observed during conventional furnace annealing of the studied microwires. A remarkable GMI ratio improvement is observed as compared to as-prepared annealed and even stress-annealed microwires. Observed magnetic softening and GMI ratio improvement have been discussed considering magnetic anisotropy induced by Oersted magnetic field during Joule heating and internal stresses relaxation.
•Manipulation of hysteresis loop of amorphous Co-rich microwires by annealing.•Coexistence of Giant magnetoimpedance effect and fast domain wall propagation in the same sample.•Observation of ...increasing of domain wall velocity under applied tensile stress.•Evidence of stress dependence of magnetostriction coefficient.
We studied effect of annealing on Giant magnetoimpedance (GMI) effect and magnetic properties of amorphous Fe and Co-rich microwires. High GMI effect has been observed in as-prepared Co-rich microwires. We observed that changing the annealing conditions we can obtain a great variety of properties in Co-rich microwire. High domain wall (DW) velocity and rectangular hysteresis loops we observed in heat treated Co-rich microwires. We observed increasing of the DW velocity under stress and coexistence of the GMI effect and fast DW propagation in the Co-rich microwires annealed at certain conditions. Fe-rich microwires with similar bulk hysteresis loop do not present considerable GMI effect. We assume that the outer domain shall of the annealed Co-rich microwire exhibiting both fast DW propagation and GMI effect has high circumferential magnetic permeability. Observed fast DW propagation in both kind of microwires is related to the fast magnetization switching within the single domain axially magnetized inner core, i.e. related to the remagnetization process of the inner part of the microwire.
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