Application of the maximum entropy method to spectral-domain optical coherence tomography for enhancing axial resolution

For the first time we applied the maximum entropy method (MEM) to spectral domain optical coherence tomography to enhance axial resolution (AR). The MEM estimates the power spectrum by fitting. For an onion with optimization of M = 70, the AR of 18.8 microm by discrete Fourier transform (DFT) was improved three times compared with peak widths. The calculation time by the MEM with M = 70 was 20 times longer than that of DFT. However, further studies are needed for practical applications, because the validity of the MEM depends on the sample structures.     

Controlled enhancement of spin-current emission by three-magnon splitting

Spin currents--the flow of angular momentum without the simultaneous transfer of electrical charge--play an enabling role in the field of spintronics. Unlike the charge current, the spin current is not a conservative quantity within the conduction carrier system. This is due to the presence of the spin-orbit interaction that couples the spin of the carriers to angular momentum in the lattice. This spin-lattice coupling acts also as the source of damping in magnetic materials, where the precessing magnetic moment experiences a torque towards its equilibrium orientation; the excess angular momentum in the magnetic subsystem flows into the lattice. Here we show that this flow can be reversed by the three-magnon splitting process and experimentally achieve the enhancement of the spin current emitted by the interacting spin waves. This mechanism triggers angular momentum transfer from the lattice to the magnetic subsystem and modifies the spin-current emission. The finding illustrates the importance of magnon-magnon interactions for developing spin-current based electronics.     

Production of catalase by fungi growing at low pH and high temperature

More than 100 fungi were isolated from cultures at pH 1.0 or 2.5 and 42-45 degrees C, and the production of catalases was investigated. Four strains produced a catalase with high stability at pH 2.0, and three of them produced two extracellular catalases and four intracellular catalases. In these four intracellular catalases, two catalases were similar to extracellular catalases in enzymatic properties and pI. These strains belonged to Aspergillus niger.