Synthesis and characterization of poly(3-thiophene acetic acid)/Fe3O4 nanocomposite

Poly(3-thiophene acetic acid)/Fe₃O₄ nanocomposite is synthesized by the precipitation of Fe₃O₄ in the presence of poly(3-thiophene acetic acid) (P3TAA). Structural, surface, morphological, thermal properties and conductivity characterization/evaluation of the nanocomposite were performed by XRD, FT-IR, TEM, TGA, and conductivity measurements, respectively. The capping of P3TAA around Fe₃O₄ nanoparticles was confirmed by FT-IR spectroscopy, the interaction being via bridging oxygens of the carboxylate and the nanoparticle surface through bidentate binding. The crystallite and particle size were obtained as 9 ± 2 nm and 11 ± 1 nm from XRD line profile fitting and TEM image analysis, respectively, which reveal nearly single crystalline nature of Fe₃O₄ nanoparticles. Magnetization measurements reveal that P3TAA coated magnetite particles do not saturate at higher fields. There is no coercivity and remanence revealing superparamagnetic character. Magnetic particle size calculated from the theoretical fitting as 9.1 nm which coincides the values determined from TEM micrographs and XRD line profile fitting. The comparison to the TEM particle size reveals slightly modified magnetically dead nanoparticle surface.     

Synthesis and characterization of poly(3-thiophenyl acetic acid) (P3TAA)-BaFe12O19 nanocomposite

We have presented a method for the fabrication of poly(3-thiophenyl acetic acid) (P3TAA)-BaFe₁₂O₁₉ nanocomposites by the in situ polymerization of P3TAA in the presence of synthesized BaFe₁₂O₁₉ nanoparticles. The nanoparticles and the nanocomposite were analyzed by XRD, FTIR, TGA, TEM, VSM and conductivity techniques for structural and physicochemical characteristics. Crystallographic analysis revealed the phase as hexaferrite and X-ray line profile fitting yielded a crystallite size of 32 nm. The particles, observed by TEM, exhibit irregular shapes and sizes between 100 and 500 nm, revealing polycrystalline character when compared with the crystallite size from XRD. FTIR and TGA analysis results show that P3TAA is conjugated to the particle surface via a carboxylate group and that the composite has a polymer content of ∼10%. Magnetic hysteresis curves do not saturate at high fields, which is a characteristic feature of fine particle systems with grain sizes smaller than 1 μm. Conductivity measurements showed a semiconductor character of the nanocomposite.     

The anomalous magnetic moment of the electron

The value of the electron's magnetic moment is a fundamental quantity in physics. Its deviation from the value expected from Dirac theory has given enormous impetus to the field of quantum theory and especially to quantum electrodynamics (QED) as the relativistic quantum field theory of electrodynamics. In fact, the measured values both for free and for bound electrons are explained by corresponding QED calculations on the part per trillion and part per billion level of accuracy, respectively. This agreement is amongst the best known in physics today. In turn, it allows highly precise determinations of related fundamental constants like the fine structure constant α or the electron mass. The present article discusses the application of the continuous Stern–Gerlach effect to the precise measurement of magnetic moments, especially of the electron bound in highly charged ions and possible tests of calculations in the framework of QED of bound states. Also, a test of QED in a more general approach by the comparison of values for the fine structure constant derived from different measurements, will be discussed.     

BiFeO3 thin films: Novel effects

In this paper we report synthesis of phase-pure highly resistive magnetoelectric BiFeO₃ thin films on Pt/TiO₂/SiO₂/Si substrate by using pulsed laser deposition technique. For the first time saturated ferroelectric hysteresis loop has been observed. It has confirmed the presence of ferroelectricity in BiFeO₃ compound. The films exhibit dielectric anomaly near Neel temperature. This anomaly is related to the influence of vanishing magnetic order on the electric order. In situ domain alignment occurs during observation of the films under transmission electron microscope.     

Electromagnetism in steadily rotating matter

Several writers have proposed quasistatic theories of moving magnetized bodies, neglecting the induced electric fields. Obviously, this excludes the possibility of analyzing radiation, which I can tolerate. However, time independent fields have been observed in some steadily rotating magnetized bodies, in particular. I will review experimental evidence for such cases, paying attention to the observed induced electric fields. It turns out that these tend to be very small in dielectrics, but not in conductors. For the latter, I will suggest a rather simple way of modifying theories to account for them. Also, for more general theories of electromagnetism, I will compare two old schemes, a non-relativistic one due to Maxwell and Lorentz and a relativistic scheme proposed by Minkowski. Among workers interested in continuum theory, the former seems to be more popular, but experimental evidence favors the latter over the former and one modern theory.     

Atom Capture by Nanotube and Scaling Anomaly

The existence of bound state of the polarizable neutral atom in the inverse square potential created by the electric field of a single walled charged carbon nanotube (SWNT) is shown to be theoretically possible. The consideration of inequivalent boundary conditions due to self-adjoint extensions lead to this nontrivial bound state solution. It is also shown that the scaling anomaly is responsible for the existence of such bound state. Binding of the polarizable atoms in the coupling constant interval η ²∈[0,1) may be responsible for the smearing of the edge of steps in quantized conductance, which has not been considered so far in the literature.     

Comparison of agarose and cross-linked protein gels as magnetic resonance imaging phantoms

Measurements of the magnetic field dependence of spin-lattice relaxation rates and the response of the water-proton signal intensity to off-resonance radio frequency fields show that the commonly used agarose phantom provides a less faithful representation for the magnetic response of tissue than does a cross-linked protein system. The origin of these differences lies in the structure and intramolecular dynamics of the macromolecular system used to make the gel. These distinctions will also cause differences in the magnetic response of the water spin system when paramagnetic relaxation agents or contrast agents are incorporated. Use of a thermally cross-linked bovine serum albumin phantom is suggested.     

Antiferromagnetically coupled multilayers of (Co90Fe10 tF/Ru tRu)×N and (Ni81Fe19 tF/Ru tRu)×N prepared by ion beam deposition

This work describes multilayers of Co₉₀Fe₁₀ t_F/Ru t_Ru/Co₉₀Fe₁₀ t_F and Ni₈₁Fe₁₉ t_F/Ru t_Ru/Ni₈₁Fe₁₉ t_F (20 Åt_F200 Å) prepared at ambient temperature by ion beam deposition on Si/SiO₂ 3 kÅ substrates. The samples exhibited a maximum antiferromagnetic coupling with t_Ru=3.2 Å and M–H curves characterized by zero remanent magnetic moment and enhanced saturation field. Antiferromagnetic peaks were present with t_Ru17 and 30 Å.     

Triangle anomaly free weak interaction with two neutral currents

Considering that the neutral interaction is free of triangle anomalies we derive an expression for the most general neutral interaction with two neutral currents. We show that the Bargers version is a special case. We also determine the interaction wheneverZ, D are mass eigen states and show that this differs from the Barger’s version in an essential way.