Exploring magnetic field treatment into solid-state fermentation of organic waste for improving structural and physiological properties of keratin peptides

This study systematically investigated the effects of a low-intensity magnetic field on the influence of keratinase activity, peptide yield, and structural and functional properties of peptides produced during solid-state fermentation (SSF) of mixed organic substrates (chicken feather powder and okara) using a mutant strain of Bacillus licheniformis. Initially, the magnetic field-assisted SSF (MSSF) conditions were optimized, which provided the optimized conditions as the number of treatments 3 at every 24 h (24, 48, and 72 h) with 4 h holding time at 120 Gs of magnetic intensity (mI). Under the optimum conditions, keratinase activity and peptide production increased by 10.31% and 13.77%, respectively. Further, in order to evaluate the influence of magnetic field treatment on the peptides, MSSF experiments were done under different mI conditions (40, 80, 120, and 160 Gs), followed by the evaluation of the structural changes of the extracted peptides. The structural analysis revealed that mI had a significant impact on the keratin surface. In contrast, secondary structure analysis confirmed the unfolding of the peptide with decreased α-keratin and increased β-keratin, thereby boosting the bioactive properties of the peptides. The highest hydroxyl free radical (.OH), 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging and Fe2+ chelating rates (56.55, 71.36, and 50.72%, respectively) were found at 120 Gs, which were insignificant with the results at 160 Gs. Therefore, MSSF has a positive effect on the proteolysis mechanism, which can increase bioactive peptide production from keratin.

Manufacturing of Surface Nanostructured Fibers Featuring an Antibacterial Effect by Magnetic Field Transportation of Magnetite@Silver Core-Shell Nanoparticles

Magnetic core-shell nanoparticles of type Fe3O4@Ag were synthesized in gram scale following a combined co-precipitation phase-transfer method and afterwards, processed to nanoparticle polymer (polypropylene and polyamide) composites. These composites were used as sheath material for the fabrication of core-sheath fibers. During the melt spinning process, a magnetic field was applied around the roving, whereby the particles move in the still liquid sheath polymer towards the surface. The produced fiber materials were investigated by AFM showing a nanostructuring of the surface, which was indirectly confirmed by determination of a slight surface tension lowering. Nanoparticle movement was shown by cross-section SEM and EDX measurements. The antibacterial activity of the spun fibers was proven by contacting them with Escherichia coli. A long-term stability of this effect was observable by carrying out a standard washability test. In contrast to previous works this new approach uses no deposition technique to introduce surface changes. It rather applies a magnetic force to move appropriately equipped nanoparticles from the inside of the fiber to the surface. This leads in only one step to a strong superficial anchoring of the particles resulting in a unique combination of long-term stable antibacterial and improved anti-soiling effects.

Enhanced magnetic properties of Ce_(17)Fe_(76.5)Co_1Zr_(0.5)B_6 alloys by magnetic field heat treatment

In the present work,Ce_(17)Fe_(76.5)Co_1Zr_(0.5)B_6 ribbons were prepared by a direct melt spinning method.The effects of chamber pressure and magnetic field annealing temperature on the magnetic properties and microstructures of the alloys were investigated.The grain size and content of Ce_(2)Fe_(14)B phase can be changed by adjusting the chamber pressure,and the optimal magnetic performance is obtained at0.04 MPa.The magnetic properties can be influenced under magnetic field heat treatment.When the annealing temperature is lower than the Curie temperature,the refinement and a uniform distribution of the grains is obtained.The irreversible magnetic susceptibility curve reveals that magnetic field heat treatment enhances the exchange coupling interaction between grains of the Ce_(2)Fe_(14)B phase.When the magnetic field annealing temperature is 438 K,the alloy displays the optimal magnetic properties.Compared with the as-spun sample,the values of intrinsic coercivity(H_(ci)),remanence(B_r) and maximum energy product((BH)max) increase by 3.4%,9.8% and 18.7%,respectively.This work provides an effective approach by which to enhance the magnetic properties of Ce-Fe-B alloys.

Research of the Interface Microstructure and Thermal Treatment of Cold-Rolled Cu-Al Composite Strip Under Magnetic Field

The thermal treatment process of cold-rolled Cu-Al composite strip under magnetic field conditions is systematically investigated by means of metallographic microscope and universal testing machine to observe the interface microstructure and test the mechanical properties.The heat treatment parameters' effects to the interface structure and mechanical properties of Al-Cu cold-rolled strip are discussed.The conclusions is showed as follows:(1)when the magnetic field intensity is greater than 0.1 T,the interface layer grow widely and stimulate the interfacial compounds' generation,the shear strength is reduced.(2)When the Cu-Al specimen's annealing temperature is at the condition of 300℃,the interfacial layer narrows when the magnetic field strength stay 0.1T than that without magnetic field,the magnetic filed restrains the interfacial compounds' generation,the shear strength reaches as high as 124Mpa;(3)The interfacial compounds are meanly brittleness intermetallic compounds such as CuAl,CuAl_2,Cu_9Al.