Magnetic fields (MF) are increasingly being applied in food processing to preserve food quality. They can be static (SMF), oscillating (OMF) or pulsed (PMF) depending on the type of equipment. The food characteristics can be influenced by several configurations of the applied magnetic field as its flux density, frequency, polarity and exposure time. Several mechanisms have been proposed to explain the effects of magnetic fields on foods. Some of them propose interactions at the subatomic particle level that show quantum behavior, such as the radical pair and cyclotron resonance mechanisms. Other proposals are at the level of DNA, compounds, subcellular organelles and cells. The interactions between food and magnetic fields are addressed in a general way in this work, highlighting the applications and action models involved and their effects on the physicochemical, enzymatic and microbiological characteristics of food.

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In this work, we have investigated the structural and optical properties of GaAs (1x) Bi x /GaAs single quantum wells (QW) grown by molecular beam epitaxy (MBE) on GaAs (311)B substrates using x-ray diffraction (XRD), atomic force microscopy (AFM), Fourier-transform Raman (FT-Raman) and photoluminescence (PL) spectroscopy techniques. The FT-Raman results revealed a decrease of the relative intensity ratio of transverse (TO) and longitudinal (LO) optical modes with the increase of Bi concentration which indicates reduction of the structural disorder with increasing Bi incorporation. In addition, the PL results show an enhancement of the optical efficiency of the structures as the Bi concentration is increased due to important effects of exciton localization related to Bi defects, non-radiative centers and alloy disorder. These results provide evidence that Bi is incorporated effectively in the QW region. Finally, the temperature dependence of PL spectra has evidenced two distinct types of defects related to the Bi incorporation, namely Bi clusters and pairs, and alloy disorder and potential fluctuation.

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Effective and controllable doping is instrumental for enabling the use of III–V semiconductor nanowires (NWs) in practical electronics and optoelectronics applications. To this end, dopants are incorporated during self-catalyzed growth via vapor–liquid–solid mechanism through the catalyst droplet or by vapor–solid mechanism of the sidewall growth. The interplay of these mechanisms together with the competition between axial elongation and radial growth of NWs can result in dopant concentration gradients along the NW axis. Here, we report an investigation of Be-doped p-type GaAs NWs grown by the self-catalyzed method on lithography-free Si/SiOx templates. The influence of dopant incorporation on the structural properties of the NWs is analyzed by scanning and transmission electron microscopy. By combining spatially resolved Raman spectroscopy and transport characterization, we are able to estimate the carrier concentration, mobility and resistivity on single-NW level. We show that Be dopants are incorporated predominantly by vapor–solid mechanism for low Be flux, while the relative contribution of vapor–liquid–solid incorporation is increased for higher Be flux, resulting in axial dopant gradients that depend on the nominal doping level.

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