Oxidation and ordering of fine structure of corn starch under an ultrahigh magnetic field.

In this study, corn starch (40 % moisture content) was placed in an ultra-high magnetic field(UMF)(5-20 T) to investigate the ordering and stabilization process under the magnetic field. With the increase of the intensity of UMF, C-OH and O-C-O were oxidized to O = C-OH and cross-linked to form ester bonds. When the UMF intensity was 15 T, the effect was the most significant with the ordered short-range structures formed; since the O = C-OR enhanced carbon skeleton structure, the crystallinity increased comparatively and amylose content reached the minimum value (15.32 ± 0.04 %). Additionally, UMF has a compressive effect on the void structure of A-type starch, and the average particle size decreased. RVA and DSC demonstrated that the UMF-treated starch had better thermal stability and shear resistance. This study suggested that UMF could serve as a prospective technique for starch product processing.

A Guided Wave Transducer with Sprayed Magnetostrictive Powder Coating for Monitoring of Aluminum Conductor Steel-Reinforced Cables.

Aluminum conductor steel-reinforced (ACSR) cables are typically used in overhead transmission lines, requiring stringent non-destructive testing owing to the severe conditions they face. Ultrasonic guided wave inspection provides promising online monitoring of the wire breakage of cables with the advantages of high sensitivity, long-range inspection, and full cross-sectional coverage. It is a very popular method to generate and receive guided waves using magnetostrictive and piezoelectric transducers. However, uniformly coupling the acoustic energy excited by transducers into multi-wire structures is always a challenge in the field application of guided waves. Long-term field application of piezoelectric transducers is limited due to the small coupling surface area, localized excitation, and couplant required. Conventional magnetostrictive transducers for steel strand inspection are based on the magnetostrictive effect of the material itself. Two factors affect the transducing performance of the transducers on ACSR cables. On one hand, there is a non-magnetostrictive effect in aluminum wires. On the other hand, the magnetostriction of the innermost steel wires is too weak to generate guided waves. The bias magnetic field is attenuated by the outer layers of aluminum wires. In this paper, an alternative sprayed magnetostrictive powder coating (SMPC) transducer was developed for guided wave generation and detection in ACSR cables. The Fe83Ga17 alloy powder with large magnetostriction was sprayed uniformly on the surfaces of certain sections of the outermost aluminum wires where the transducer would be installed. Experimental investigations were carried out to generate and receive the most commonly used L(0,1) guided waves for wire breakage detection at frequencies of 50 and 100 kHz. The results demonstrate that the discernable reflected waves of the cable end and an artificial defect of three-wire breakage (5.5% reduction in the cable's cross-sectional area) were received by the transducer with SMPC, which was impossible for the transducer without SMPC. This method makes long-term and online monitoring of ACSR cables feasible due to the high coupling efficiency and good structural surface adaptability.