Soft Magnetic Properties of Nanocrystalline Fe-Cu-Nb-Si-B Thin Films and Multilayers

Structural and magnetic properties of Fe-Cu-Nb-Si-B thin films and multilayers produced by rf sputtering have been investigated. The thin films 1μm thick are of an amorphous phase in the as-deposited state and their annealed ones are of a crystallized bcc phase with fine grains of nanometer size. The crystallization behavior is similar to those of the melt-quenched ribbons with the same composition. The crystallized films possess a saturation magnetic flux density of 1.3 T higher than that of the ribbons and good soft magnetic properties. For improving magnetic permeability in the high frequency region, an attempt has been made to fabricate Fe-Cu-Nb-Si-B / SiO_2 multilayers. It has been found that an [Fe_Cu_Nb_-Si_B_ (5, 000Å) / SiO_2 (50Å)]_2 multilayer annealed at 500℃ for 1 h also consists of bcc fine crystallites and exhibits low coercivity of about 0.08 Oe and permeability as high as 7, 000 at 1 MHz. Furthermore, the field annealed multilayers exhibit much higher permeability of about 10, 200 at 1 MHz

Novel Dielectric Nanogranular Materials with an Electrically Tunable Frequency Response

Abstract The electrical modulation of the functionality of matter is of significant interest in physics and multifunctional tunable electronic device applications. Here, new dielectric materials with nanogranular structures comprised of nano‐sized Co granular metals dispersed in a Mg‐fluoride‐based dielectric matrix are explored. The dielectric relaxation frequency (fr), which represents a sharp decrease in dielectric permittivity in dielectrics, can be tuned by a DC electric field (E). As E increases, the position of fr first shifts to the low‐frequency side and then to the high‐frequency side, achieving a tunable fr in a certain frequency range. The ability to electrically modulate the relaxation frequency may help construct novel tunable frequency filters. The dielectric properties are theoretically examined based on the asymmetric electron tunnelling model that considers the size difference of granular pairs, offering an insightful understanding of the structure‐property relationship in disordered granular solids

Characterization and Structural Analysis of a Novel <i>exo</i>-Type Enzyme Acting on β‑1,2-Glucooligosaccharides from <i>Parabacteroides distasonis</i>

β-1,2-Glucan is a polysaccharide produced mainly by some Gram-negative bacteria as a symbiosis and infectious factor. We recently identified <i>endo</i>-β-1,2-glucanase from <i>Chitinophaga pinensis</i> (<i>Cp</i>SGL) as an enzyme comprising a new family. Here, we report the characteristics and crystal structure of a <i>Cp</i>SGL homologue from <i>Parabacteroides distasonis</i>, an intestinal bacterium (BDI_3064 protein), which exhibits distinctive properties of known β-1,2-glucan-degrading enzymes. BDI_3064 hydrolyzed linear β-1,2-glucan and β-1,2-glucooligosaccharides with degrees of polymerization (DPs) of ≥4 to produce sophorose specifically but did not hydrolyze cyclic β-1,2-glucan. This result indicates that BDI_3064 is a new <i>exo</i>-type enzyme. BDI_3064 also produced sophorose from β-1,2-glucooligosaccharide analogues that have a modified reducing end, indicating that BDI_3064 acts on its substrates from the nonreducing end. The crystal structure showed that BDI_3064 possesses additional N-terminal domains 1 and 2, unlike <i>Cp</i>SGL. Superimposition of BDI_3064 and <i>Cp</i>SGL complexed with ligands showed that R93 in domain 1 overlapped subsite −3 in <i>Cp</i>SGL. Docking analysis involving a β-1,2-glucooligosaccharide with DP4 showed that R93 completely blocks the nonreducing end of the docked β-1,2-glucooligosaccharide. This indicates that BDI_3064 employs a distinct mechanism of recognition at the nonreducing end of substrates to act as an <i>exo</i>-type enzyme. Thus, we propose 2-β-d-glucooligosaccharide sophorohydrolase (nonreducing end) as a systematic name for BDI_3064