Application of Hashin-Shtrikman bounds homogenization model for frequency analysis of imperfect FG bio-composite plates.

Despite abundant theoretical investigations on the dynamic behavior of functionally graded (FG) structures, the study on frequency analysis of FG bio-composite structures is limited. FG bio-composite materials due to their biocompatibility potentials and good material properties can be applied in biomedical applications, especially dental implants. In this investigation, a natural frequency response of the FG bio-composite plate is analyzed within the framework of the newly developed refined higher-order shear deformation plate theory. Additionally, the imperfection impact on frequency behavior is evaluated while three imperfection distribution patterns are taken into account. The constitutive materials of FG bio-composite plate are Hydroxyapatite and Titanium. The effective material properties of the structure are determined with the help of the upper Hashin-Shtrikman bounds homogenization model. In continuation, to solve the derived governing equations of imperfect FG bio-composite plate, Galerkin's analytical method is employed. Also, the precision of the used theory is validated, the obtained outcomes are compared and an acceptable matching is found. Later, the sensitivity of different considerable variables is comprehensively assessed and discussed.

Effects of ultrasonic assisted cooking on the chemical profiles of taste and flavor of spiced beef.

The objective of this study was to assess the effects of ultrasonic assisted cooking on the chemical profiles of spiced beef taste and flavor. Ultrasound power with 0 W, 400 W, 600 W, 800 W and 1000 W (frequency of 20 kHz) were used for cooking 120 min. The sodium chloride, sugar, free amino acids (FAAs), 5'-ribonucleotides, lipid oxidation, volatile flavor substance contents and electronic nose of spiced beef were determined. Results showed that ultrasonic treatment could significantly increase the content of sodium chloride in beef sample (P < 0.05). When the ultrasonic power lower than 1000 W, the content of sugar and 5'-ribonucleotides could be increased significantly compared with the control (P < 0.05). The essential amino acid content and the essential amino acid/non-essential ratios (E/NE) were significantly increased with the ultrasound treatment (P < 0.05). The lipid oxidation showed that ultrasound resulted in the increased of TBARS values compared with control significantly (P < 0.05), but no significant differences were shown among the different ultrasonic power groups (P > 0.05). With the ultrasonic treatment, the types and relative content of volatile flavor substances were significantly increased (P < 0.05), especially for aldehydes, alcohols and ketones. However, there was no significant variation among the different ultrasound power groups (P > 0.05). This result was consistent with the measurement of electronic nose. Data points of control samples were away from ultrasonic treatment groups, while data points of different ultrasonic treatment groups were flock together. The results indicate that the application of ultrasound during cooking has a positive effect on chemical profiles of spiced beef taste and flavor, particularly for the power of 800 W.

Changes in calpain activity, protein degradation and microstructure of beef M. semitendinosus by the application of ultrasound.

In this investigation, samples were treated by ultrasonic probe (20 kHz) at an intensity of 25 W cm-2 for 20 or 40 min, followed by aging at 4 °C for 1, 3 and 7 d. Ultrasound treatment significantly increased myofibrillar fragmentation index (MFI) and decreased Warner-Bratzler shear force (WBSF) at 3 and 7 d of postmortem aging (P < .05). Ultrasound-treated samples showed significantly greater intensities of autolyzed 76 kDa subunits and the lower intensity of intact 80 kDa form compared to control at 1 d of storage (P < .05). Significant difference was found between semitendinosus (ST) samples treated for both 20 and 40 min (P < .05). Ultrasound treated samples showed increased proteolysis during the postmortem storage as reflected by an increased degradation of desmin and troponin-T. These results showed that ultrasound treatment could improve the tenderness of beef ST muscle through regulating the calpain activation and protein degradation during postmortem aging.

Effects of power ultrasound on oxidation and structure of beef proteins during curing processing.

The aim of this study was to evaluate the effects of power ultrasound intensity (PUS, 2.39, 6.23, 11.32 and 20.96Wcm(-2)) and treatment time (30, 60, 90 and 120min) on the oxidation and structure of beef proteins during the brining procedure with 6% NaCl concentration. The investigation was conducted with an ultrasonic generator with the frequency of 20kHz and fresh beef at 48h after slaughter. Analysis of TBARS (Thiobarbituric acid reactive substances) contents showed that PUS treatment significantly increased the extent of lipid oxidation compared to static brining (P<0.05). As indicators of protein oxidation, the carbonyl contents were significantly affected by PUS (P<0.05). SDS-PAGE analysis showed that PUS treatment increased protein aggregation through disulfide cross-linking, indicated by the decreasing content of total sulfhydryl groups which would contribute to protein oxidation. In addition, changes in protein structure after PUS treatment are suggested by the increases in free sulfhydryl residues and protein surface hydrophobicity. Fourier transformed infrared spectroscopy (FTIR) provided further information about the changes in protein secondary structures with increases in ß-sheet and decreases in α-helix contents after PUS processing. These results indicate that PUS leads to changes in structures and oxidation of beef proteins caused by mechanical effects of cavitation and the resultant generation of free radicals.